阅读说明：本技术 曲面屏幕的厚度测量系统、方法及装置 (Thickness measuring system, method and device for curved screen ) 是由 周翔 雷志辉 陈状 刘宇 傅丹 于 2021-07-23 设计创作，主要内容包括：本申请涉及一种曲面屏幕的厚度测量系统,其包括：文件获取模块,用于获取单条激光线下第一相机单元和第二相机单元分别拍摄的曲面屏幕的点激光条纹系列标定图像,提取光斑亚像素位置；亚像素中心获取模块,用于分别获取预设位置处的曲面屏幕的点激光成像,获取每个角度的点激光成像,并提取对应的光斑亚像素中心；高度偏差确定模块,用于将不同角度下的光斑亚像素中心的集合转换到预设坐标系下,获取相应的高度修正模型；曲率计算模块,用于根据高度修正模型得到曲面屏幕所在位置的倾斜角,获得曲面屏幕的完整3D形貌,并计算各个点的曲率值。本申请还公开一种曲面屏幕的厚度测量方法和一种曲面屏幕的厚度测量装置。(The application relates to a thickness measurement system of curved surface screen, it includes: the file acquisition module is used for acquiring point laser stripe series calibration images of the curved screen, which are respectively shot by the first camera unit and the second camera unit under a single laser line, and extracting the sub-pixel positions of light spots; the sub-pixel center acquisition module is used for respectively acquiring point laser images of the curved screen at preset positions, acquiring point laser images of each angle and extracting corresponding light spot sub-pixel centers; the height deviation determining module is used for converting the set of the light spot sub-pixel centers at different angles to a preset coordinate system to obtain a corresponding height correction model; and the curvature calculation module is used for obtaining the inclination angle of the position of the curved screen according to the height correction model, obtaining the complete 3D appearance of the curved screen and calculating the curvature value of each point. The application also discloses a thickness measuring method of the curved screen and a thickness measuring device of the curved screen.)

1. A system for measuring the thickness of a curved screen, comprising:

the file acquisition module is used for acquiring point laser stripe series calibration images of the curved screen, which are respectively shot by the first camera unit and the second camera unit under a single laser line, extracting light spot sub-pixel positions of the point laser stripe series calibration images according to point laser imaging characteristics, and acquiring calibration parameter files under the series heights;

the sub-pixel center acquisition module is used for respectively acquiring point laser images of the curved screen shot by the first camera unit and the second camera unit at preset positions, acquiring point laser images of each angle, and extracting corresponding light spot sub-pixel centers of the point laser images to acquire a set of light spot sub-pixel centers;

the height deviation determining module is used for converting the set of the light spot sub-pixel centers under different angles into a preset coordinate system and determining height deviation values of the first camera unit and the second camera unit under different angles so as to obtain corresponding height correction models;

and the curvature calculation module is used for obtaining the inclination angle of the position of the curved screen according to the height correction model, correcting to obtain the complete 3D shape of the curved screen, and calculating the curvature value of each point.

2. The system for measuring the thickness of a curved screen of claim 1, wherein the file acquisition module comprises:

the filtering processing unit is used for filtering the acquired point laser stripe series calibration image of the curved screen;

the gray level calculating unit is used for calculating the mean value of each gray level by taking the pixel coordinate of the point laser stripe series calibration image after filtering processing as the center and determining the position of the maximum value of the mean value of the gray levels;

the algorithm template construction unit is used for performing center extraction processing according to the point laser stripe series calibration images after filtering processing and acquiring an LOG algorithm parameter template;

the sub-pixel position obtaining unit is used for calculating a LOG algorithm response value according to the position of the maximum value of the mean value of the gray scale and the LOG algorithm parameter template to determine the position with the maximum response value, and fitting the position with the maximum response value to obtain a light spot sub-pixel position;

and the calibration parameter file generating unit is used for acquiring the pixel height corresponding to the calibration height of each point laser stripe series calibration image and generating a calibration parameter file according to the calibration height.

3. The system for measuring the thickness of a curved screen according to claim 2, wherein the sub-pixel position obtaining unit is configured to calculate a LOG algorithm response value according to a position where the mean value of the gray scale is located and the LOG algorithm parameter template to determine a position where the response value is maximum, and fit the position where the response value is maximum to obtain the spot sub-pixel position, and includes:

setting a fitting polynomial;

setting a formula of the sum of the distances from each selected point in the image coordinate system to the polynomial curve;

constructing a fitting matrix according to the sum of the distances from the points to the polynomial curve;

coefficients are calculated for each term in the fitted polynomial.

4. The system for measuring the thickness of a curved screen of claim 2, wherein said sub-pixel center acquisition module comprises:

the point laser imaging acquisition unit is used for respectively acquiring point laser imaging at the preset position through the first camera unit and the second camera unit and acquiring point laser imaging of each angle;

and the sub-pixel center extraction unit is used for extracting the corresponding spot sub-pixel center of the point laser imaging.

5. The system for measuring the thickness of a curved screen of claim 4, wherein the height deviation determination module comprises:

the coordinate system conversion unit is used for converting the set of the light spot sub-pixel centers to the preset coordinate system;

the height calculation unit is used for performing linear interpolation on a preset point in the converted set of the light spot sub-pixel centers and four points close to the pixel height of the preset point, and calculating a height set corresponding to the preset point;

and the model building unit is used for calculating height deviation values of the first camera unit and the second camera unit under different angles according to the height set transmitted by the height calculating unit so as to obtain a height correction model under any angle.

6. The curved screen thickness measurement system of claim 5, wherein the curvature calculation module comprises:

the contour line measuring unit is used for measuring an outer contour curve of the curved screen;

the inclination angle calculation unit is used for calculating the average value of the height offset of the first camera unit and the second camera unit of each point on the outer contour curve of the curved screen and obtaining the inclination angle of the curved screen;

the height curve acquisition unit is used for calculating to obtain a height curve of the measuring track based on the inclination angle of the curved screen and correcting to obtain the complete 3D appearance of the curved screen;

and the curvature calculating unit is used for calculating the curvature value of each point on the outer contour curve of the curved screen.

7. The system for measuring the thickness of a curved screen of claim 1, wherein the predetermined position is a horizontal designated position and the predetermined coordinate system is a world coordinate system.

8. The system for measuring the thickness of a curved screen according to any one of claims 1 to 7, wherein the single laser line is emitted by a laser unit, the first camera unit and the second camera unit constitute a single line binocular system, and the first camera unit and the second camera unit respectively have different angles with the laser line emitted by the laser unit.

9. A method for measuring the thickness of a curved screen, which is performed by the system for measuring the thickness of a curved screen according to any one of claims 1 to 8, wherein the method for measuring the thickness of a curved screen comprises:

acquiring point laser stripe series calibration images of a curved screen, which are respectively shot by a first camera unit and a second camera unit under a single laser line, extracting the light spot sub-pixel positions of the point laser stripe series calibration images obtained by processing, and acquiring calibration parameter files under the series heights;

respectively acquiring point laser images of the curved screen shot by the first camera unit and the second camera unit at preset positions, and extracting corresponding spot sub-pixel centers of the point laser images at each angle to acquire a set of the spot sub-pixel centers;

converting the set of the sub-pixel centers of the light spots under different angles into a preset coordinate system, and determining the height deviation values of the first camera unit and the second camera unit under different angles to obtain corresponding height correction models;

and obtaining the inclination angle of the position of the curved screen according to the height correction model, correcting to obtain the complete 3D appearance of the curved screen, and calculating the curvature value of each point.

10. The method for measuring the thickness of the curved screen according to claim 9, wherein the obtaining of the calibration images of the series of the point laser stripes of the curved screen, which are respectively photographed by the first camera unit and the second camera unit under the single laser line, the extracting of the spot sub-pixel positions of the calibration images of the series of the point laser stripes obtained by the processing, and the obtaining of the calibration parameter files under the series of heights comprises:

filtering the point laser stripe series calibration image of the curved screen;

calculating the mean value of each gray level by taking the pixel coordinates of the point laser stripe series calibration images after filtering as the center, and determining the position of the maximum value of the mean value of the gray levels;

performing center extraction processing on the point laser stripe series calibration image after filtering processing, and acquiring a LOG algorithm parameter template;

calculating a LOG algorithm response value according to the position of the maximum mean value of the gray scale and the LOG algorithm parameter template to determine the position with the maximum response value, and fitting the position with the maximum response value to obtain a light spot sub-pixel position;

and acquiring the pixel height corresponding to the calibration height of each point laser stripe series calibration image, and generating a corresponding calibration parameter file.

11. The method for measuring the thickness of a curved screen according to claim 10, wherein the step of calculating a LOG algorithm response value according to the position of the maximum mean value of the gray scale and the LOG algorithm parameter template to determine the position of the maximum response value, and fitting the position of the maximum response value to obtain the sub-pixel position of the light spot comprises the steps of:

setting a fitting polynomial;

setting a formula of the sum of the distances from each selected point in the image coordinate system to the polynomial curve;

constructing a fitting matrix according to the sum of the distances from the points to the polynomial curve;

coefficients are calculated for each term in the fitted polynomial.

12. The method for measuring the thickness of a curved screen according to claim 10, wherein the obtaining of the point laser images of the curved screen taken by the first camera unit and the second camera unit at preset positions respectively, and extracting the corresponding spot sub-pixel centers of the point laser images for each angle to obtain the set of spot sub-pixel centers comprises:

respectively acquiring point laser images at the preset positions through the first camera unit and the second camera unit to obtain point laser images of each angle;

extracting corresponding spot sub-pixel centers of the spot laser imaging to obtain a set of the spot sub-pixel centers.

13. The method for measuring the thickness of a curved screen according to claim 12, wherein the transforming the set of sub-pixel centers of the light spots at different angles to a preset coordinate system, and determining the height deviation values of the first camera unit and the second camera unit at different angles to obtain the corresponding height correction models, comprises:

converting the set of the light spot sub-pixel centers to be under the preset coordinate system;

performing linear interpolation on a preset point in the converted set of the light spot sub-pixel centers and four points close to the pixel height of the preset point, and calculating a height set corresponding to the preset point;

and calculating height deviation values of the first camera unit and the second camera unit under different angles according to the height set so as to obtain a height correction model under any angle.

14. The method for measuring the thickness of the curved screen according to claim 13, wherein the obtaining of the inclination angle of the position of the curved screen according to the height correction model, the correction of the complete 3D shape of the curved screen, and the calculation of the curvature value of each point comprise:

measuring an outer contour curve of the curved screen;

obtaining the inclination angle of the curved screen according to the average value of the height offset of the first camera unit and the second camera unit of each point on the outer contour curve of the curved screen;

obtaining a height curve of a measuring track based on the inclination angle of the curved screen, and correcting to obtain the complete 3D appearance of the curved screen;

and calculating the curvature value of each point on the outer contour curve of the curved screen.

15. A thickness measuring device of a curved screen, comprising: at least one processor and storage, at least one of the processor executing computer-executable instructions stored by the storage, at least one of the processor performing the method of measuring thickness of a curved screen according to any one of claims 9 to 14.

Technical Field

The present disclosure relates to the field of optical measurement, and more particularly, to a thickness measuring system for a curved screen, a thickness measuring method for a curved screen, and a thickness measuring device for a curved screen.

Background

With the continuous iteration of the development of electronic devices such as mobile phones, curved screens with better visual experience than flat screens come into play. The curved surface screen not only can avoid the too big uncomfortable tired of eyeball that arouses of stadia at screen both ends, and the radian of curved surface screen can guarantee moreover that the distance of eyes is even to can bring better visual experience. Meanwhile, the appearance screen of the curved screen is slightly bent, so that a better surrounding type appearance can be provided, and a more deep ornamental vision is provided for a user. In addition, a contrast adjustment mechanism aiming at color depth is added in the aspect of image processing, so that the viewing effect of 2D pictures and 3D pictures can be improved, and the pictures have more visual perception. Compared with a flat display device, an important parameter of a curved display device is the curvature of a curved screen, i.e., the degree of curvature of the curved screen.

Although curved screens do bring about excellent visual effects, and more flexible and reliable human-computer interaction logic. Then, since the production process of the Organic Light-Emitting Diode (OLED) screen developed in the present day is still not mature, the process detection standard becomes the largest technical challenge, which severely restricts the working efficiency of the curved screen production line of the electronic device such as the mobile phone.

Disclosure of Invention

In view of the defects in the prior art, the application aims to provide a thickness measuring system for a curved screen, which aims to solve the problems of immature process, low working efficiency and the like in the existing measuring method.

A system for measuring the thickness of a curved screen, comprising: the file acquisition module is used for acquiring point laser stripe series calibration images of the curved screen, which are respectively shot by the first camera unit and the second camera unit under a single laser line, extracting light spot sub-pixel positions of the point laser stripe series calibration images according to point laser imaging characteristics, and acquiring calibration parameter files under the series heights; the sub-pixel center acquisition module is used for respectively acquiring point laser images of the curved screen shot by the first camera unit and the second camera unit at preset positions, acquiring point laser images of each angle, and extracting corresponding light spot sub-pixel centers of the point laser images to acquire a set of light spot sub-pixel centers; the height deviation determining module is used for converting the set of the light spot sub-pixel centers under different angles into a preset coordinate system and determining height deviation values of the first camera unit and the second camera unit under different angles so as to obtain corresponding height correction models; and the curvature calculation module is used for obtaining the inclination angle of the position of the curved screen according to the height correction model, correcting to obtain the complete 3D shape of the curved screen, and calculating the curvature value of each point.

Optionally, the file obtaining module includes: the filtering processing unit is used for filtering the acquired point laser stripe series calibration image of the curved screen; the gray level calculating unit is used for calculating the mean value of each gray level by taking the pixel coordinate of the point laser stripe series calibration image after filtering processing as the center and determining the position of the maximum value of the mean value of the gray levels; the algorithm template construction unit is used for performing center extraction processing according to the point laser stripe series calibration images after filtering processing and acquiring an LOG algorithm parameter template; the sub-pixel position obtaining unit is used for calculating a LOG algorithm response value according to the position of the maximum value of the mean value of the gray scale and the LOG algorithm parameter template to determine the position with the maximum response value, and fitting the position with the maximum response value to obtain a light spot sub-pixel position; and the calibration parameter file generating unit is used for acquiring the pixel height corresponding to the calibration height of each point laser stripe series calibration image and generating a calibration parameter file according to the calibration height.

Optionally, the sub-pixel position obtaining unit is configured to calculate a LOG algorithm response value according to a position where the mean value of the gray scale is located and the LOG algorithm parameter template to determine a position where the response value is maximum, and fit the position where the response value is maximum to obtain a spot sub-pixel position, and includes: setting a fitting polynomial; setting a formula of the sum of the distances from each selected point in the image coordinate system to the polynomial curve; constructing a fitting matrix according to the sum of the distances from the points to the polynomial curve; coefficients are calculated for each term in the fitted polynomial.

Optionally, the sub-pixel center obtaining module includes: the point laser imaging acquisition unit is used for respectively acquiring point laser imaging at the preset position through the first camera unit and the second camera unit and acquiring point laser imaging of each angle; and the sub-pixel center extraction unit is used for extracting the corresponding spot sub-pixel center of the point laser imaging.

Optionally, the height deviation determining module comprises: the coordinate system conversion unit is used for converting the set of the light spot sub-pixel centers to the preset coordinate system; the height calculation unit is used for performing linear interpolation on a preset point in the converted set of the light spot sub-pixel centers and four points close to the pixel height of the preset point, and calculating a height set corresponding to the preset point; and the model building unit is used for calculating height deviation values of the first camera unit and the second camera unit under different angles according to the height set transmitted by the height calculating unit so as to obtain a height correction model under any angle.

Optionally, the curvature calculation module comprises: the contour line measuring unit is used for measuring an outer contour curve of the curved screen; the inclination angle calculation unit is used for calculating the average value of the height offset of the first camera unit and the second camera unit of each point on the outer contour curve of the curved screen and obtaining the inclination angle of the curved screen; the height curve acquisition unit is used for calculating to obtain a height curve of the measuring track based on the inclination angle of the curved screen and correcting to obtain the complete 3D appearance of the curved screen; and the curvature calculating unit is used for calculating the curvature value of each point on the outer contour curve of the curved screen.

Optionally, the preset position is a horizontal designated position, and the preset coordinate system is a world coordinate system.

Optionally, the single laser line is emitted by a laser unit, the first camera unit and the second camera unit form a single-line binocular system, and included angles between the first camera unit and the second camera unit and laser lines emitted by the laser unit are different.

To sum up, the thickness measurement system of curved surface screen that this application provided can realize measuring curved surface screen product to the effectual work efficiency who improves curved surface screen production line has improved the market competition rate of product.

Based on the same inventive concept, the application also provides a thickness measuring method of the curved screen, which comprises the following steps: acquiring point laser stripe series calibration images of a curved screen, which are respectively shot by a first camera unit and a second camera unit under a single laser line, extracting the light spot sub-pixel positions of the point laser stripe series calibration images obtained by processing, and acquiring calibration parameter files under the series heights; respectively acquiring point laser images of the curved screen shot by the first camera unit and the second camera unit at preset positions, and extracting corresponding spot sub-pixel centers of the point laser images at each angle to acquire a set of the spot sub-pixel centers; converting the set of the sub-pixel centers of the light spots under different angles into a preset coordinate system, and determining the height deviation values of the first camera unit and the second camera unit under different angles to obtain corresponding height correction models; and obtaining the inclination angle of the position of the curved screen according to the height correction model, correcting to obtain the complete 3D appearance of the curved screen, and calculating the curvature value of each point.

Optionally, the obtaining a calibration image of a series of point laser stripes of the curved screen, which is shot by the first camera unit and the second camera unit respectively under the single laser line, extracting the sub-pixel positions of the light spots of the calibration image of the series of point laser stripes obtained by the processing, and obtaining a calibration parameter file under the series of heights includes: filtering the point laser stripe series calibration image of the curved screen; calculating the mean value of each gray level by taking the pixel coordinates of the point laser stripe series calibration images after filtering as the center, and determining the position of the maximum value of the mean value of the gray levels; performing center extraction processing on the point laser stripe series calibration image after filtering processing, and acquiring a LOG algorithm parameter template; calculating a LOG algorithm response value according to the position of the maximum mean value of the gray scale and the LOG algorithm parameter template to determine the position with the maximum response value, and fitting the position with the maximum response value to obtain a light spot sub-pixel position; and acquiring the pixel height corresponding to the calibration height of each point laser stripe series calibration image, and generating a corresponding calibration parameter file.

Optionally, the calculating a LOG algorithm response value according to the position of the maximum mean value of the gray scale and the LOG algorithm parameter template to determine a position with a maximum response value, and fitting the position with the maximum response value to obtain a spot sub-pixel position includes: setting a fitting polynomial; setting a formula of the sum of the distances from each selected point in the image coordinate system to the polynomial curve; constructing a fitting matrix according to the sum of the distances from the points to the polynomial curve; coefficients are calculated for each term in the fitted polynomial.

Optionally, the respectively obtaining point laser images of the curved screen shot by the first camera unit and the second camera unit at preset positions, and extracting corresponding spot sub-pixel centers of the point laser images at each angle to obtain the set of spot sub-pixel centers includes: respectively acquiring point laser images at the preset positions through the first camera unit and the second camera unit to obtain point laser images of each angle; extracting corresponding spot sub-pixel centers of the spot laser imaging to obtain a set of the spot sub-pixel centers.

Optionally, the converting the set of sub-pixel centers of the light spot at different angles to a preset coordinate system, and determining height deviation values of the first camera unit and the second camera unit at different angles to obtain corresponding height correction models include: converting the set of the light spot sub-pixel centers to be under the preset coordinate system; performing linear interpolation on a preset point in the converted set of the light spot sub-pixel centers and four points close to the pixel height of the preset point, and calculating a height set corresponding to the preset point; and calculating height deviation values of the first camera unit and the second camera unit under different angles according to the height set so as to obtain a height correction model under any angle.

Optionally, the obtaining, according to the height correction model, an inclination angle of a position where the curved screen is located, correcting to obtain a complete 3D morphology of the curved screen, and calculating a curvature value of each point includes: measuring an outer contour curve of the curved screen; obtaining the inclination angle of the curved screen according to the average value of the height offset of the first camera unit and the second camera unit of each point on the outer contour curve of the curved screen; obtaining a height curve of a measuring track based on the inclination angle of the curved screen, and correcting to obtain the complete 3D appearance of the curved screen; and calculating the curvature value of each point on the outer contour curve of the curved screen.

In summary, the method for measuring the thickness of the curved screen can realize measurement of curved screen products, so that the working efficiency of a curved screen production line is effectively improved, and the market competitiveness of the products is improved.

Based on the same inventive concept, the present application also provides a thickness measuring device of a curved screen, which comprises: at least one processor and storage, at least one said processor carries out the computer execution instruction that said storage stores, at least one said processor carries out the thickness measurement method of said curved screen.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a thickness measurement system of a curved screen according to an embodiment of the present disclosure;

FIG. 2 is a schematic structural diagram of a file acquisition module of the thickness measurement system for curved screens shown in FIG. 1;

FIG. 3 is a schematic structural diagram of a sub-pixel center acquisition module of the thickness measurement system of the curved screen shown in FIG. 1;

FIG. 4 is a schematic diagram of a height deviation determination module of the thickness measurement system for the curved screen shown in FIG. 1;

FIG. 5 is a schematic diagram of a curvature calculation module of the thickness measurement system for the curved screen shown in FIG. 1;

fig. 6 is a schematic flowchart of a method for measuring a thickness of a curved screen according to an embodiment of the present disclosure;

fig. 7 is a schematic flowchart of step S10 in the thickness measuring method of the curved screen shown in fig. 6;

fig. 8 is a schematic flowchart of step S20 in the thickness measuring method of the curved screen shown in fig. 6;

fig. 9 is a schematic flowchart of step S30 in the thickness measuring method of the curved screen shown in fig. 6;

fig. 10 is a schematic flowchart of step S40 in the thickness measuring method of the curved screen shown in fig. 6;

fig. 11 is a schematic hardware structure diagram of a thickness measuring device for a curved screen according to an embodiment of the present application.

Detailed Description

To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present application are given in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

The following description of the various embodiments refers to the accompanying drawings, which are included to illustrate specific embodiments that can be implemented by the application. The numbering of the components as such, e.g., "first", "second", etc., is used herein only to distinguish the objects as described, and does not have any sequential or technical meaning. The term "connected" and "coupled" when used in this application, unless otherwise indicated, includes both direct and indirect connections (couplings). Directional phrases used in this application, such as, for example, "upper," "lower," "front," "rear," "left," "right," "inner," "outer," "side," and the like, refer only to the orientation of the appended drawings and are, therefore, used herein for better and clearer illustration and understanding of the application and are not intended to indicate or imply that the device or element so referred to must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the application.

In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as being fixedly connected, detachably connected, or integrally connected; may be a mechanical connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art. It should be noted that the terms "first", "second", and the like in the description and claims of the present application and in the drawings are used for distinguishing between different objects and not for describing a particular order. Furthermore, the terms "comprises," "comprising," "includes," "including," or "including," when used in this application, specify the presence of stated features, operations, elements, and/or the like, but do not limit one or more other features, operations, elements, and/or the like. Furthermore, the terms "comprises" or "comprising" indicate the presence of the respective features, numbers, steps, operations, elements, components or combinations thereof disclosed in the specification, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, elements, components or combinations thereof, and are intended to cover non-exclusive inclusions.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

With the continuous iteration of the development of electronic devices such as mobile phones, curved screens with better visual experience than flat screens come into play. The curved surface screen not only can avoid the too big uncomfortable tired of eyeball that arouses of stadia at screen both ends, and the radian of curved surface screen can guarantee moreover that the distance of eyes is even to can bring better visual experience. Meanwhile, the appearance screen of the curved screen is slightly bent, so that a better surrounding type appearance can be provided, and a more deep ornamental vision is provided for a user. In addition, a contrast adjustment mechanism aiming at color depth is added in the aspect of image processing, so that the viewing effect of 2D pictures and 3D pictures can be improved, and the pictures have more visual perception. Compared with a flat display device, an important parameter of a curved display device is the curvature of a curved screen, i.e., the degree of curvature of the curved screen. Although curved screens do bring about excellent visual effects, and more flexible and reliable human-computer interaction logic. Then, since the production process of the Organic Light-Emitting Diode (OLED) screen developed in the present day is still not mature, the process detection standard becomes the largest technical challenge, which severely restricts the working efficiency of the curved screen production line of the electronic device such as the mobile phone.

Based on this, the present application hopes to provide a solution to the above technical problem, which can realize the detection of the curved screen products of the electronic devices such as mobile phones, thereby effectively improving the working efficiency of the curved screen production line of the electronic devices, and the details of which will be explained in the following embodiments.

It is understood that the electronic device may include a Personal Digital Assistant (PDA) and/or an electronic device with a music player function, such as a mobile phone, a tablet computer, a wearable electronic device with a wireless communication function (e.g., a smart watch), and the like. In some embodiments, the electronic device may have a communication function, that is, may establish communication with a network through a 2G (second generation mobile phone communication specification), a 3G (third generation mobile phone communication specification), a 4G (fourth generation mobile phone communication specification), a 5G (fifth generation mobile phone communication specification), or a W-LAN (wireless local area network) or a communication method that may appear in the future. For the sake of brevity, the embodiment of the present application is not further limited, and the present application takes the electronic device as a mobile phone as an example for description.

Please refer to fig. 1, which is a schematic structural diagram of a thickness measuring system of a curved screen according to an embodiment of the present application. As shown in fig. 1, in the embodiment of the present application, the present application provides a thickness measuring system 100 for a curved screen, which at least includes a document acquiring module 110, a sub-pixel center acquiring module 120, a height deviation determining module 130, and a curvature calculating module 140. The file obtaining module 110 is electrically connected to the sub-pixel center obtaining module 120, the sub-pixel center obtaining module 120 is electrically connected to the height deviation determining module 130, and the height deviation determining module 130 is electrically connected to the curvature calculating module 140. That is, the file obtaining module 110, the sub-pixel center obtaining module 120, the height deviation determining module 130, and the curvature calculating module 140 are electrically connected in sequence.

The file obtaining module 110 is configured to obtain a calibration image of a series of point laser stripes of a curved screen, which is shot by a first camera unit and a second camera unit respectively under a single laser line, extract a light spot sub-pixel position of the calibration image of the series of point laser stripes according to a point laser imaging characteristic, obtain a calibration parameter file at a series of heights, and transmit the light spot sub-pixel position to the sub-pixel center obtaining module 120.

In an embodiment of the present application, the single laser line may be emitted by a laser unit, which may be a laser (laser). The laser unit, the first camera unit and the second camera unit form a single-line binocular system, and included angles between the first camera unit and the second camera unit and laser lines emitted by the laser unit are different. It is understood that the laser unit and the first camera unit may be used to form a first subsystem, the laser unit and the second camera unit may be used to form a second subsystem, and the first subsystem and the second subsystem are both single-line monocular systems.

In this embodiment of the application, the file acquiring module 110 acquires a series of calibration images of a point laser stripe of a curved screen shot by the first camera unit and the second camera unit under a single laser line through an interval moving device, where the interval moving device may be a height displacement table.

In the embodiment of the application, the curved screen is a curved flexible screen.

The sub-pixel center obtaining module 120 is configured to obtain point laser images of the curved screen shot by the first camera unit and the second camera unit at preset positions, obtain point laser images of each angle, extract a corresponding light spot sub-pixel center of the point laser images, and transmit a set of the extracted light spot sub-pixel centers to the height deviation determining module 130.

Specifically, in this embodiment of the application, the sub-pixel center obtaining module 120 obtains point laser images of the curved screen shot by the first camera unit and the second camera unit under a single laser line at a preset position respectively, and with a current position as a 0-degree reference, the point laser images at each angle are obtained by rotating the goniometer at equal intervals, so as to extract the spot sub-pixel centers at different angles of the point laser images, and obtain a set of the spot sub-pixel centers. Wherein the preset position is a horizontal designated position.

The height deviation determining module 130 is configured to convert the set of sub-pixel centers of the light spot at different angles, which is transmitted by the sub-pixel center acquiring module 120, into a preset coordinate system, determine height deviation values of the first camera unit and the second camera unit at different angles to acquire a height correction model at any angle, and transmit the acquired height correction model to the curvature calculating module 140.

Specifically, in this embodiment of the application, the height deviation determining module 130 is configured to convert the set of spot sub-pixel centers at different angles of the spot laser image transmitted by the sub-pixel center obtaining module 120 into a preset coordinate system through a calibration parameter file, determine height deviation values of the first camera unit and the second camera unit at different angles, and obtain a height correction model at any angle through a B-spline model (B-spline model). And the preset coordinate system is a world coordinate system.

In an embodiment of the present application, the height deviation values of the first camera unit and the second camera unit at different angles are height deviation values of the first camera unit and the second camera unit, where each time the angle gauge rotates by one angle, a sub-pixel center of a spot of light is collected in each of the first camera unit and the second camera unit. And after the sub-pixel center of the point light spot is converted to the real height of a world coordinate system through a calibration parameter file, the height deviation value of the first camera unit and the second camera unit is the height of the first camera unit minus the height of the second camera unit.

The curvature calculation module 140 is configured to obtain an inclination angle of the position of the curved screen according to the height correction model obtained by the height deviation determination module 130, correct the inclination angle to obtain a complete 3D shape of the curved screen, and calculate a curvature value of each point.

Specifically, in the embodiment of the present application, the movement direction and the step length of the horizontal interval moving device are controlled to scan the area where the curved screen to be measured is located, the height deviation values of the first camera unit and the second camera unit at different angles are determined, the inclination angle of the position where the curved screen is located is obtained through the height correction model obtained by the height deviation determining module 130, the complete 3D shape of the curved screen in the scanning area is obtained through a correction formula, the curvature value of each point is calculated, and a curvature change scatter diagram is drawn through the obtained curvature value of each point. Wherein the inclination angle refers to an inclination angle between the curved screen and a placing plane.

Please refer to fig. 2, which is a schematic structural diagram of the file acquiring module 110 of the thickness measuring system of the curved screen shown in fig. 1. As shown in fig. 2, the file obtaining module 110 includes a filtering processing unit 111, a gray level calculating unit 112, an algorithm template constructing unit 113, a sub-pixel position obtaining unit 114, and a calibration parameter file generating unit 115. The filtering processing unit 111 is electrically connected to the gray level calculating unit 112, the gray level calculating unit 112 is electrically connected to the algorithm template constructing unit 113, the algorithm template constructing unit 113 is electrically connected to the sub-pixel position obtaining unit 114, and the sub-pixel position obtaining unit 114 is electrically connected to the calibration parameter file generating unit 115. That is, the filtering processing unit 111, the gray level calculating unit 112, the algorithm template constructing unit 113, the sub-pixel position obtaining unit 114, and the calibration parameter file generating unit 115 are electrically connected in sequence.

In this embodiment, the filtering processing unit 111 is configured to perform filtering processing on the acquired point laser stripe series calibration image of the curved screen, and transmit the point laser stripe series calibration image after the filtering processing to the grayscale calculating unit 112.

Specifically, in the embodiment of the present application, the first camera unit and the second camera unit acquire a series of calibration images of the point laser stripe series by moving the measured plane at a certain interval by using a one-dimensional height displacement stage, and the filter processing unit 111 performs gaussian filtering on the acquired calibration images of the point laser stripe series of the curved screen as calibration data. Wherein the formula of the Gaussian function is:

where σ is the template size.

Wherein, the filtered image is: g (x, y) ═ f (x, y) × G (x, y) — a convolution.

The gray level calculating unit 112 is configured to calculate a mean value of each gray level by taking the pixel coordinates of the filtered point laser stripe series calibration image transmitted by the filtering processing unit 111 as a center, and determine a position where a maximum value of the mean value of the gray levels is located.

Specifically, in this embodiment of the application, the gray level calculating unit 112 calculates the mean value of each gray level by using a surrounding 5 × 5 template according to the pixel coordinate of the calibrated image of the point laser fringe series after the gaussian filtering process transmitted by the filtering processing unit 111 as the center, and performs the image border crossing process, so as to determine the position where the maximum value of the mean value of the gray levels is located, which is denoted as the position a. Wherein the image out-of-range processing comprises: and respectively processing the height and the width of the image coordinate system, wherein the processing range of the height is 2 to 3 higher than the image, and the processing range of the width is 2 to 3 higher than the image.

The algorithm template construction unit 113 is configured to perform center extraction processing according to the filtered point laser fringe series calibration image transmitted by the filter processing unit 111, obtain a LOG algorithm parameter template, and transmit the LOG algorithm parameter template obtained through calculation to the sub-pixel position obtaining unit 114.

Specifically, in the embodiment of the present application, the algorithm template constructing unit 113 performs LOG algorithm center extraction according to the filtered point laser stripe series calibration image, and calculates the LOG algorithm parameter template through a LOG algorithm expression. It can be understood that the point laser imaging is different from the conventional laser stripe image, only laser speckles exist, and the mathematical structure of the laser speckles is close to the Mexican grass hat shape; the speckle center extraction device consists of an excitation central area and an inhibition peripheral area, and extracts the speckle center.

And the LOG algorithm parameter template is a LOG algorithm parameter template of 7 × 7 templates. The LOG algorithm expression is as follows:

the sub-pixel position obtaining unit 114 is configured to calculate a LOG algorithm response value according to a position where the mean value of the gray scale is located and the LOG algorithm parameter template to determine a position where the response value is maximum, fit the position where the response value is maximum to obtain a light spot sub-pixel position, and transmit the obtained light spot sub-pixel position to the calibration parameter file generating unit 115.

Specifically, in this embodiment of the application, the sub-pixel position obtaining unit 114 calculates a LOG algorithm response value through the LOG algorithm parameter template transmitted by the algorithm template constructing unit 113 in a range of about 10 × 10 with a position (i.e., a position) where the maximum value of the gray-scale mean value is located as a center, determines a position where the response value is maximum as an entire pixel position B (xPos, yPos) of the spot laser speckle, and performs secondary fitting of up and down 3 points (7 points in total) in the horizontal and vertical directions with the position B as a center to obtain a spot sub-pixel position C (xPos + dx, yPos + dy). Wherein, the calculation process of dx and dy comprises the following steps:

setting a fitting polynomial;

specifically, the function expression of the fitting polynomial is: a is₀+a₁x+…+a_kx^kFormula (3);

setting a formula of the sum of the distances from each selected point in the image coordinate system to the polynomial curve;

specifically, the functional expression of the sum of the distances from each selected point in the image coordinate system to the polynomial curve is as follows:

constructing a fitting matrix according to the sum of the distances from the points to the polynomial curve;

specifically, the function expression of the fitting matrix is as follows:

calculating coefficients of each term in the fitting polynomial;

specifically, after a fitting matrix is established, when the coefficient of each item of the fitting polynomial is calculated, K in the formula (5) is assigned according to the power series of the fitting polynomial, when the power series of the fitting polynomial is quadratic fitting of least square, K is equal to 2, when the power series of the fitting polynomial is cubic fitting of least square, K is equal to 3, and then the selected coordinates of each point are respectively substituted into the formula (5) to calculate the coefficient of each item of the fitting polynomial.

In the embodiment of the present application, the upper and lower 3 points that are horizontal and vertical with the position B as the center are respectively substituted into the matrix of formula (5), assuming that K is 2, the true values of a0, a1, and a2 are obtained by the matrix calculation of formula (5), and the polynomial curve function expression is: a is₀+a₁x+a₂x²Wherein, in the step (A),the actual parameters are the transverse and longitudinal directions.

The calibration parameter file generating unit 115 is configured to obtain a pixel height corresponding to a calibration height of each of the point laser stripe series calibration images, and generate a calibration parameter file according to the calibration height.

Specifically, the calibration parameter file generating unit 115 sequentially obtains the pixel heights corresponding to the calibration heights of the point laser stripe series calibration images, and generates corresponding calibration parameter files in an increasing order of the calibration heights.

Please refer to fig. 3, which is a schematic structural diagram of the sub-pixel center obtaining module 120 of the thickness measuring system of the curved screen shown in fig. 1. As shown in fig. 3, the sub-pixel center acquiring module 120 includes a point laser imaging acquiring unit 121 and a sub-pixel center extracting unit 122. The spot laser imaging acquiring unit 121 is electrically connected to the sub-pixel center extracting unit 122.

In this embodiment of the application, the point laser imaging obtaining unit 121 is configured to obtain point laser images at preset positions through the first camera unit and the second camera unit, obtain point laser images at each angle, and transmit the collected point laser images to the sub-pixel center extracting unit 122.

Specifically, the point laser imaging obtaining unit 121 obtains point laser images of the curved screen shot by the first camera unit and the second camera unit under a single laser line at a horizontally specified position, and collects 21 point laser speckle images of-20 degrees to 20 degrees by rotating the goniometer at equal intervals with the current position as a reference 0 position before angle adjustment. Wherein, the rotation of the angle gauge at equal intervals is 2 degrees, and the front high and the back low are defined as positive angles.

The sub-pixel center extracting unit 122 is configured to extract a corresponding spot sub-pixel center of the spot laser image, and transmit the set of spot sub-pixel centers to the height deviation determining module 130.

Specifically, the sub-pixel center extracting unit 122 processes the spot laser speckle image transmitted by the spot laser imaging acquiring unit 121 to obtain a spot sub-pixel center of the LOG operator of the spot laser fringe series calibration image, and transmits the set of spot sub-pixel centers to the height deviation determining module 130.

Please refer to fig. 4, which is a schematic structural diagram of the height deviation determining module 130 of the thickness measuring system of the curved screen shown in fig. 1. As shown in fig. 4, the height deviation determination module 130 includes a coordinate system conversion unit 131, a height calculation unit 132, and a model construction unit 133. The height calculating unit 132 is electrically connected to the coordinate system converting unit 131 and the model constructing unit 133.

In this embodiment, the coordinate system converting unit 131 is configured to convert the set of spot sub-pixel centers transmitted by the sub-pixel center extracting unit 122 into a preset coordinate system, and transmit the converted set of spot sub-pixel centers to the height calculating unit 132.

Specifically, the set of the light spot sub-pixel centers of the first camera unit and the second camera unit is converted into the preset coordinate system through a calibration parameter file, and the converted set of the light spot sub-pixel centers is recorded as a set Zc (divided into Zc)_{Left side of}And Zc_{Right side}) Taking the C (xc, yc) point as an example, the most consistent with the pixel height yc is foundNear four points, which are respectively noted as: c1(y1, z1), C2(y2, z2), C3(y3, z3), C4(y4, z4), wherein y1<y2<yc<y3<y 4. And the preset coordinate system is a world coordinate system.

The height calculating unit 132 is configured to perform linear interpolation on a preset point in the set of the converted light spot sub-pixel centers and four points close to the pixel height of the preset point, calculate a height set corresponding to the preset point, and transmit the height set to the model building unit 133.

Specifically, taking the point C as the preset point, in the set of the converted sub-pixel centers of the light spot, performing linear interpolation operation on the preset point C and four points C1, C2, C3, and C4 that are close to the pixel height of the preset point C, solving a height set corresponding to the preset point C, and transmitting the height set to the model building unit 133. Wherein, the height calculation formula of the point C is as follows:

the model building unit 133 is configured to calculate height deviation values of the first camera unit and the second camera unit at different angles according to the height set transmitted by the height calculating unit 132 to obtain a height correction model at any angle, and transmit the obtained height correction model to the curvature calculating module 140.

Specifically, in the embodiment of the present application, the model building unit 133 is configured to determine a height deviation value of the first camera unit and the second camera unit at different angles, and acquire a height correction model at any angle through a B-spline model (B-spline model). The system calibration process ensures that the height deviation value of the reference image is close to 0, a height correction model is built through a B-spline model, the function correspondence between the height deviation value and the inclination angle can be determined, and the B-spline model is as follows:

when the cubic spline function S (x), x ∈ [ a, b ]]And in each cell [ x ]_j,x_j+1]The above are all cubic polynomials,wherein a ═ x₀<x₁<...<x_nB is a given node, and at node x_jFunction value y given above_j＝f(x_j) (j ═ 0, 1.. times, n), with the formation of S (x)_j)＝y_jThen S (x) is node x₀,x₁,...,x_nCubic spline function of (a). As can be seen from the above, S (x) is required, and [ x ] is required in each cell_j,x_j+1]The four undetermined coefficients are determined by the cubic polynomial, and the total number of the four undetermined coefficients is n, so that 4n parameters are determined.

S (x) in [ a, b)]The upper second derivative is continuous, then node x_jThe continuity condition S (x) should be satisfied at (j ═ 1, 2.., n-1)_j-dx)＝S(x_j+dx)，S′(x_j-dx)＝S′(x_j+dx)，S″(x_j-dx)＝S″(x_j+ dx) where dx is infinitesimal, there are 3n-3 conditions, and S (x) is added to satisfy the interpolation condition S (x)_j)＝y_j(j ═ 0,1,. times, n), for a total of 4n-2 conditions; the left and right curvature end points of the full screen to be supplemented should be the minimum value, namely S' (x)₀)＝0,S'(x_n) A total of 4n parameters solves the spline function s (x) at 0.

Please refer to fig. 5, which is a schematic structural diagram of a curvature calculating module 140 of the thickness measuring system of the curved screen shown in fig. 1. As shown in fig. 5, the curvature calculation module 140 includes a contour line measurement unit 141, a tilt angle calculation unit 142, a height curve acquisition unit 143, and a curvature calculation unit 144. The contour line measuring unit 141 is electrically connected to the tilt angle calculating unit 142, the tilt angle calculating unit 142 is electrically connected to the height curve obtaining unit 143, and the height curve obtaining unit 143 is electrically connected to the curvature calculating unit 144.

The contour line measuring unit 141 is configured to measure an outer contour curve of the curved screen, and transmit the obtained outer contour curve of the curved screen to the tilt angle calculating unit 142.

Specifically, the contour line measuring unit 141 presets a measuring track, and controls the interval moving device to trigger, so as to preset step length and equal interval point laser amount to the outer contour curve of the curved screen. Wherein, the measurement point number of the outer contour curve of the curved surface screen is equal to the triggering frequency, and the set step length is 1 um.

The tilt angle calculation unit 142 is configured to calculate a mean value of height offsets of the first camera unit and the second camera unit at each point on the outer contour curve of the curved screen, obtain a tilt angle of the curved screen, and transmit the tilt angle of the curved screen to the height curve acquisition unit 143.

Specifically, the inclination angle calculation unit 142 calculates the height offset of the first camera unit and the second camera unit at each point on the outer contour curve of the curved screen, calculates a corresponding height offset mean value based on the height offset, and obtains the inclination angle of the curved screen through the height correction model.

The height curve acquiring unit 143 is configured to calculate a height curve of the measurement track based on the inclination angle of the curved screen, correct the height curve to obtain a complete 3D shape of the curved screen, and transmit the obtained height curve of the measurement track to the curvature calculating unit 144.

Specifically, the height curve obtaining unit 143 calculates the average of the height values of the first camera unit and the second camera unit that calculate each point on the outer contour curve of the curved screen to obtain an average value of 0.5 × Z_{c left side}+0.5*Z_{c right side}Subtracting the height value of the reference image from the mean value to obtain a reference deviation value Z_{c partial pressure}And then calculating by a correction formula to obtain a height curve of the measuring track.

Wherein, the coordinate of each point on the outer contour curve of the curved screen eliminates the modulation of height H to dy caused by the inclination angle through a correction formula, and corrects the Y coordinate

The curvature calculating unit 144 is configured to calculate a curvature value of each point on the outer contour curve of the curved screen.

Specifically, the curvature calculating unit 144 constructs an equidistant coordinate system (where the abscissa is a trigger counting number and the ordinate is a solving height corresponding to the starting point), performs quadratic fitting of 5 points, calculates a curvature value of each point through a curvature solving formula, and draws a curvature change scatter diagram. Wherein, the curvature solving formula is as follows:

referring to fig. 6, which is a schematic flow chart of a method for measuring thickness of a curved screen according to an embodiment of the present disclosure, the system for measuring thickness of a curved screen in the embodiments shown in fig. 1 to 5 measures the screen thickness of an electronic product such as a mobile phone by using the following method for measuring thickness of a curved screen, so as to effectively improve the working efficiency of a production line of a curved screen of an electronic product such as a mobile phone. In this embodiment, the curved screen is made of a transparent material. As shown in fig. 6, the method for measuring the thickness of the curved screen at least includes the following steps.

S10, point laser stripe series calibration images of the curved screen, which are respectively shot by the first camera unit and the second camera unit under a single laser line, are obtained, the light spot sub-pixel positions of the point laser stripe series calibration images are extracted, and calibration parameter files under the series heights are obtained.

In this embodiment, please refer to fig. 1, the file obtaining module 110 obtains a calibration image of a series of spot laser stripes of a curved screen, which is shot by the first camera unit and the second camera unit respectively under a single laser line, extracts a spot sub-pixel position of the calibration image of the series of spot laser stripes according to a spot laser imaging characteristic, obtains a calibration parameter file under a series of heights, and transmits the center of the spot sub-pixel to the sub-pixel center obtaining module 120.

In the embodiment of the present application, referring to fig. 7 in combination with fig. 2, the step S10 at least includes the following steps.

And S11, filtering the point laser stripe series calibration image of the curved screen.

Specifically, the filtering processing unit 111 performs filtering processing on the acquired point laser stripe series calibration image of the curved screen, and transmits the point laser stripe series calibration image after filtering processing to the gray level calculating unit 112.

In the embodiment of the present application, the first camera unit and the second camera unit acquire a series of calibration images of the point laser stripe series by moving the measured plane at certain intervals by using a one-dimensional height electric displacement stage, and the filter processing unit 111 performs gaussian filter processing on the acquired calibration images of the point laser stripe series of the curved screen as calibration data. Wherein the formula of the Gaussian function is:

where σ is the template size.

Wherein, the filtered image is: g (x, y) ═ f (x, y) × G (x, y) — a convolution.

And S12, calculating the mean value of each gray scale by taking the pixel coordinates of the point laser stripe series calibration image after filtering processing as the center, and determining the position of the maximum value of the mean value of the gray scales.

Specifically, the gray level calculating unit 112 calculates the mean value of each gray level by taking the pixel coordinate of the filtered point laser stripe series calibration image transmitted by the filtering processing unit 111 as the center, and determines the position of the maximum value of the mean value of the gray levels.

In this embodiment of the application, the gray level calculating unit 112 calculates the mean value of each gray level by using a surrounding 5 × 5 template according to the pixel coordinate of the dot laser stripe series calibration image after gaussian filtering transmitted by the filtering processing unit 111 as the center, and performs image border crossing processing, so as to determine the position where the maximum value of the mean value of the gray levels is located, which is denoted as a position a. Wherein the image out-of-range processing comprises: and respectively processing the height and the width of the image coordinate system, wherein the processing range of the height is 2 to 3 higher than the image, and the processing range of the width is 2 to 3 higher than the image.

And S13, performing center extraction processing on the point laser stripe series calibration images after filtering processing, and acquiring a LOG algorithm parameter template.

Specifically, the algorithm template constructing unit 113 performs LOG algorithm center extraction according to the filtered point laser fringe series calibration image transmitted from the filter processing unit 111, calculates a LOG algorithm parameter template, and transmits the calculated LOG algorithm parameter template to the sub-pixel position obtaining unit 114.

In the embodiment of the present application, the algorithm template constructing unit 113 performs LOG algorithm center extraction according to the filtered point laser stripe series calibration image, and calculates the LOG algorithm parameter template through a LOG algorithm expression. It can be understood that the point laser imaging is different from the conventional laser stripe image, only laser speckles exist, and the mathematical structure of the laser speckles is close to the Mexican grass hat shape; the speckle center extraction device consists of an excitation central area and an inhibition peripheral area, and extracts the speckle center.

And the LOG algorithm parameter template is a LOG algorithm parameter template of 7 × 7 templates. The LOG algorithm expression is as follows:

s14, calculating a LOG algorithm response value according to the position of the maximum mean value of the gray scale and the LOG algorithm parameter template, determining the position with the maximum response value, and fitting the position with the maximum response value to obtain the sub-pixel position of the light spot.

Specifically, the sub-pixel position obtaining unit 114 calculates a LOG algorithm response value according to the position of the maximum value of the gray-scale mean value and the LOG algorithm parameter template to determine the position of the maximum response value, fits the position of the maximum response value to obtain a light spot sub-pixel position, and transmits the obtained light spot sub-pixel position to the calibration parameter file generating unit 115.

In this embodiment, the sub-pixel position obtaining unit 114 calculates the LOG algorithm response value through the LOG algorithm parameter template transmitted from the algorithm template constructing unit 113 in a range of about 10 × 10 with the position (i.e., position a) where the maximum value of the gray-scale mean value is located as the center, determines that the position where the response value is maximum is the whole pixel position B (xPos, yPos) of the spot laser speckle, and performs secondary fitting of 3 vertical upper and lower points (total 7 points) with the position B as the center to obtain the spot sub-pixel position C (xPos + dx, yPos + dy). Wherein, the calculation process of dx and dy comprises the following steps:

setting a fitting polynomial;

specifically, the function expression of the fitting polynomial is: a is₀+a₁x+…+a_kx^kFormula (3);

setting a formula of the sum of the distances from each selected point in the image coordinate system to the polynomial curve;

specifically, the functional expression of the sum of the distances from each selected point in the image coordinate system to the polynomial curve is as follows:

constructing a fitting matrix according to the sum of the distances from the points to the polynomial curve;

specifically, the function expression of the fitting matrix is as follows:

calculating coefficients of each term of the fitting polynomial;

specifically, after a fitting matrix is established, when the coefficient of each item of the fitting polynomial is calculated, K in the formula (5) is assigned according to the power series of the fitting polynomial, when the power series of the fitting polynomial is quadratic fitting of least square, K is equal to 2, when the power series of the fitting polynomial is cubic fitting of least square, K is equal to 3, and then the selected coordinates of each point are respectively substituted into the formula (5) to calculate the coefficient of each item of the fitting polynomial.

In the embodiment of the present application, the upper and lower 3 points which are horizontal and vertical with the position B as the center are respectively substituted intoIn the matrix of equation (5), assuming that K is 2, the true values of a0, a1, and a2 are obtained by the matrix calculation of equation (5), and the polynomial curve function expression is: a is₀+a₁x+a₂x²Wherein, in the step (A),the actual parameters are the transverse and longitudinal directions.

And S15, acquiring the pixel height corresponding to the calibration height of each point laser stripe series calibration image, and generating a corresponding calibration parameter file.

Specifically, the calibration parameter file generating unit 115 obtains a pixel height corresponding to the calibration height of each of the point laser stripe series calibration images, and generates a calibration parameter file according to the calibration height.

S20, point laser images of the curved screen shot by the first camera unit and the second camera unit at preset positions are respectively obtained, and the corresponding light spot sub-pixel centers of the point laser images at each angle are extracted to obtain the set of the light spot sub-pixel centers.

In this embodiment, please refer to fig. 1, the sub-pixel center obtaining module 120 obtains point laser images of the curved screen shot by the first camera unit and the second camera unit at preset positions, obtains the point laser images at each angle, extracts a corresponding spot sub-pixel center of the point laser images, and transmits a set of the extracted spot sub-pixel centers to the height deviation determining module 130.

Specifically, in this embodiment of the application, the sub-pixel center obtaining module 120 obtains point laser images of the curved screen shot by the first camera unit and the second camera unit under a single laser line at a preset position respectively, and with a current position as a 0-degree reference, the point laser images at each angle are obtained by rotating the goniometer at equal intervals, so as to extract the spot sub-pixel centers at different angles of the point laser images, and obtain a set of the spot sub-pixel centers. Wherein the preset position is a horizontal designated position.

In the embodiment of the present application, referring to fig. 8 in combination with fig. 3, the step S20 at least includes the following steps.

And S21, respectively acquiring point laser images at preset positions through the first camera unit and the second camera unit to obtain point laser images at each angle.

Specifically, the point laser imaging obtaining unit 121 obtains point laser images at preset positions through the first camera unit and the second camera unit, obtains point laser images at each angle, and transmits the collected point laser images to the sub-pixel center extracting unit 122.

In this embodiment of the application, the point laser imaging obtaining unit 121 obtains point laser images of the curved screen shot by the first camera unit and the second camera unit under a single laser line at a horizontal designated position, respectively, and collects 21 point laser speckle images of-20 degrees to 20 degrees by taking a current position as a reference 0 position before angle adjustment and rotating an angle gauge at equal intervals. Wherein, the rotation of the angle gauge at equal intervals is 2 degrees, and the front high and the back low are defined as positive angles.

And S22, extracting the corresponding spot sub-pixel centers of the point laser imaging to obtain the set of the spot sub-pixel centers.

Specifically, the sub-pixel center extracting unit 122 extracts the corresponding spot sub-pixel center of the spot laser image, and transmits the set of spot sub-pixel centers to the height deviation determining module 130.

In this embodiment of the application, the sub-pixel center extracting unit 122 processes the spot laser speckle image transmitted by the spot laser imaging acquiring unit 121 to obtain a spot sub-pixel center of the LOG operator of the calibration image of the spot laser fringe series, and transmits the set of the spot sub-pixel centers to the height deviation determining module 130.

And S30, converting the set of the sub-pixel centers of the light spots under different angles into a preset coordinate system, and determining the height deviation values of the first camera unit and the second camera unit under different angles to obtain corresponding height correction models.

In this embodiment, referring to fig. 1, the height deviation determining module 130 converts the sub-pixel centers of the light spots at different angles, which are transmitted by the sub-pixel center acquiring module 120, into a preset coordinate system, determines height deviation values of the first camera unit and the second camera unit at different angles to acquire a height correction model at any angle, and transmits the acquired height correction model to the curvature calculating module 140.

In the embodiment of the present application, referring to fig. 9 in combination with fig. 4, the step S30 at least includes the following steps.

And S31, converting the set of the light spot sub-pixel centers into a preset coordinate system.

Specifically, the coordinate system converting unit 131 converts the set of spot sub-pixel centers transmitted by the sub-pixel center extracting unit 122 into a preset coordinate system, and transmits the converted set of spot sub-pixel centers to the height calculating unit 132.

In this embodiment of the present application, the set of the sub-pixel centers of the light spot of the first camera unit and the second camera unit is converted into the preset coordinate system through a calibration parameter file, and the converted set of the sub-pixel centers of the light spot is recorded as a set Zc (divided into Zc)_{Left side of}And Zc_{Right side}) Taking C (xc, yc) point as an example, four points closest to the pixel height yc are found, and the four points are respectively marked as: c1(y1, z1), C2(y2, z2), C3(y3, z3), C4(y4, z4), wherein y1<y2<yc<y3<y 4. And the preset coordinate system is a world coordinate system.

And S32, performing linear interpolation on a preset point in the converted set of the light spot sub-pixel centers and four points close to the pixel height of the preset point, and calculating a height set corresponding to the preset point.

Specifically, the height calculating unit 132 performs linear interpolation on a preset point in the set of the converted spot sub-pixel centers and four points close to the pixel height of the preset point, calculates a height set corresponding to the preset point, and transmits the height set to the model constructing unit 133.

In this embodiment of the application, taking the point C as the preset point, in the set of the converted sub-pixel centers of the light spot, performing linear interpolation operation on the preset point C and four points C1, C2, C3, and C4 that are close to the pixel height of the preset point C, solving a height set corresponding to the preset point C, and transmitting the height set to the model building unit 133. Wherein, the height calculation formula of the point C is as follows:

and S33, calculating height deviation values of the first camera unit and the second camera unit under different angles according to the height set to obtain a height correction model under any angle.

Specifically, the model building unit 133 calculates the height deviation values of the first camera unit and the second camera unit at different angles from the height set transmitted by the height calculating unit 132 to obtain a height correction model at any angle, and transmits the obtained height correction model to the curvature calculating module 140.

In this embodiment, the model building unit 133 is configured to determine height deviation values of the first camera unit and the second camera unit at different angles, and acquire a height correction model at any angle through a B-spline model (B-spline model). The system calibration process ensures that the height deviation value of the reference image is close to 0, a height correction model is built through a B-spline model, the function correspondence between the height deviation value and the inclination angle can be determined, and the B-spline model is as follows:

when the cubic spline function S (x), x ∈ [ a, b ]]And in each cell [ x ]_j,x_j+1]All above are cubic polynomials, where a ═ x₀<x₁<...<x_nB is a given node, and at node x_jFunction value y given above_j＝f(x_j) (j ═ 0, 1.. times, n), with the formation of S (x)_j)＝y_jThen callS (x) is node x₀,x₁,...,x_nCubic spline function of (a). As can be seen from the above, S (x) is required, and [ x ] is required in each cell_j,x_j+1]The four undetermined coefficients are determined by the cubic polynomial, and the total number of the four undetermined coefficients is n, so that 4n parameters are determined.

S (x) in [ a, b)]The upper second derivative is continuous, then node x_jThe continuity condition S (x) should be satisfied at (j ═ 1, 2.., n-1)_j-dx)＝S(x_j+dx)，S′(x_j-dx)＝S′(x_j+dx)，S″(x_j-dx)＝S″(x_j+ dx) where dx is infinitesimal, there are 3n-3 conditions, and S (x) is added to satisfy the interpolation condition S (x)_j)＝y_j(j ═ 0,1,. times, n), for a total of 4n-2 conditions; the left and right curvature end points of the full screen to be supplemented should be the minimum value, namely S' (x)₀)＝0,S'(x_n) A total of 4n parameters solves the spline function s (x) at 0.

S40, obtaining the inclination angle of the position of the curved screen according to the height correction model, correcting to obtain the complete 3D shape of the curved screen, and calculating the curvature value of each point.

In this embodiment, referring to fig. 1, the curvature calculating module 140 obtains an inclination angle of the position of the curved screen according to the height correction model obtained by the height deviation determining module 130, corrects the inclination angle to obtain a complete 3D shape of the curved screen, and calculates a curvature value of each point.

In the embodiment of the present application, referring to fig. 10 in combination with fig. 5, the step S40 at least includes the following steps.

And S41, measuring the outer contour curve of the curved screen.

Specifically, the contour line measuring unit 141 measures an outer contour curve of the curved screen, and transmits the obtained outer contour curve of the curved screen to the inclination angle calculating unit 142.

In this embodiment of the application, the contour line measuring unit 141 presets a measuring track, and controls the interval moving device to trigger, so as to preset step length and equal interval point laser amount to the outer contour curve of the curved screen. Wherein, the measurement point number of the outer contour curve of the curved surface screen is equal to the triggering frequency, and the set step length is 1 um.

And S42, obtaining the inclination angle of the curved screen according to the average value of the height offset of the first camera unit and the second camera unit of each point on the outer contour curve of the curved screen.

Specifically, the tilt angle calculation unit 142 calculates a mean value of height offsets of the first camera unit and the second camera unit at each point on the outer contour curve of the curved screen, obtains the tilt angle of the curved screen, and transmits the tilt angle of the curved screen to the height curve acquisition unit 143.

In this embodiment, the tilt angle calculation unit 142 calculates the height offset of the first camera unit and the second camera unit at each point on the outer contour curve of the curved screen, calculates a corresponding height offset mean value based on the height offset, and obtains the tilt angle of the curved screen through the height correction model.

And S43, obtaining a height curve of the measuring track based on the inclination angle of the curved screen, and correcting to obtain the complete 3D shape of the curved screen.

Specifically, the height curve obtaining unit 143 calculates a height curve of the measurement trajectory based on the inclination angle of the curved screen, corrects the height curve to obtain the complete 3D shape of the curved screen, and transmits the obtained height curve of the measurement trajectory to the curvature calculating unit 144.

In this embodiment, the height curve obtaining unit 143 calculates the average of the height values of the first camera unit and the second camera unit at each point on the outer contour curve of the curved screen to obtain an average value of 0.5 × Z_{c left side}+0.5*Z_{c right side}Subtracting the height value of the reference image from the mean value to obtain a reference deviation value Z_{c partial pressure}And then calculating by a correction formula to obtain a height curve of the measuring track.

Wherein, the coordinate of each point on the outline curve of the curved screen eliminates the modulation of height H to dy caused by the inclination angle through a correction formula, and Y is locatedBidding correction

And S44, calculating the curvature value of each point on the outer contour curve of the curved screen.

Specifically, the curvature calculating unit 144 calculates a curvature value of each point on the outer contour curve of the curved screen.

In the embodiment of the present application, the curvature calculating unit 144 constructs an equidistant coordinate system (where the abscissa is a trigger count number and the ordinate is a solving height corresponding to the starting point), performs quadratic fitting of 5 points, calculates a curvature value of each point through a curvature solving formula, and draws a curvature change scatter diagram.

Wherein, the curvature solving formula is as follows:

please refer to fig. 11, which is a schematic diagram of a hardware structure of a thickness measuring device for a curved screen according to an embodiment of the present application. As shown in fig. 11, a thickness measuring apparatus 200 for a curved screen provided in an embodiment of the present application includes at least one processor 201 and a memory 202. The thickness measuring device 200 of the curved screen further includes at least one bus 203. The processor 201 and the memory 202 are electrically connected by a bus 203. The thickness measuring device 200 of the curved screen may be a computer or a server, and the application is not particularly limited thereto.

The thickness measuring device 200 for the curved screen may further include a thickness measuring system for the curved screen as in the embodiments of fig. 1 to 5 described above. In a specific implementation process, the at least one processor 201 executes the computer-executable instructions stored in the memory 202, so that the at least one processor 201 executes the thickness measurement method of the curved screen according to the embodiment shown in fig. 6 to 10 by using the thickness measurement system of the curved screen.

For a specific implementation process of the processor 201 provided in the embodiment of the present application, reference may be made to the embodiments of the thickness measurement method for a curved screen in the embodiments described in fig. 6 to fig. 10, which have similar implementation principles and technical effects, and details are not described here again in this embodiment.

In this embodiment, the curved screen is a flexible screen made of a transparent material.

It is understood that the Processor 201 may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The steps of a method provided in connection with the present application may be embodied directly in a hardware processor, or in a combination of the hardware and software modules included in the processor.

The Memory 202 may be a Random Access Memory (RAM) or a Non-Volatile Memory (NVM).

The bus 203 may be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, an Extended ISA (enhanced Industry Standard Architecture) bus, or the like. For ease of illustration, the bus 203 in the figures of the present application is not limited to only one bus or one type of bus.

It should be understood that the application of the present application is not limited to the above examples, and that modifications or changes may be made by those skilled in the art based on the above description, and all such modifications and changes are intended to fall within the scope of the appended claims.