阅读说明：本技术 一种面向印刷显示的打印高度控制系统及方法 (Printing height control system and method for printing display ) 是由 尹周平 陈建魁 潘浩 雷春耀 高俊伟 于 2020-05-26 设计创作，主要内容包括：本发明提供一种面向印刷显示的打印高度控制系统及方法,包括：喷头升降模块、基板固定模块、第一传感器、第二传感器、传感器控制器和运动驱控器；喷头升降模块包括喷头、喷头装夹装置和升降机构；基板固定模块设置于喷头升降模块下方,其包括吸附平台；第一传感器、第二传感器用于检测喷嘴至基板之间的实时距离,生成第一、第二检测原始信号；传感器控制器用于获取第一、第二检测原始信号,并经信号处理和修正运算发送至运动驱控器；运动驱控器用于对升降机构进行全闭环控制和驱动。本发明通过构建打印高度控制系统和两种传感器的结合布置,对多种检测对象的测量值修正构建高度或者位置关系,可以更好地实现无接触式自适应打印高度定位控制。(The invention provides a printing height control system and method for printing display, which comprises the following steps: the device comprises a spray head lifting module, a substrate fixing module, a first sensor, a second sensor, a sensor controller and a motion driving controller; the spray head lifting module comprises a spray head, a spray head clamping device and a lifting mechanism; the substrate fixing module is arranged below the spray head lifting module and comprises an adsorption platform; the first sensor and the second sensor are used for detecting the real-time distance between the nozzle and the substrate and generating a first detection original signal and a second detection original signal; the sensor controller is used for acquiring a first detection original signal and a second detection original signal, and sending the first detection original signal and the second detection original signal to the motion driving and controlling device through signal processing and correction operation; the motion driving and controlling device is used for carrying out full closed-loop control and driving on the lifting mechanism. The invention corrects the measured values of various detection objects to construct height or position relation by constructing the printing height control system and the combination arrangement of the two sensors, and can better realize the non-contact self-adaptive printing height positioning control.)

1. A print height control system for a print display oriented inkjet printing of a panel substrate, comprising: the device comprises a spray head lifting module (10), a substrate fixing module (20), a first sensor (60), a second sensor (50), a sensor controller (40) and a motion drive controller (30);

the spray head lifting module (10) comprises a spray head, a spray head clamping device and a lifting mechanism; the lower end of the spray head is provided with a spray nozzle, the spray head clamping device is used for fixing the spray head, and the lifting mechanism is connected with the spray head clamping device and is used for driving the spray head and the spray head clamping device to perform lifting movement, so that the printing height is positioned;

the substrate fixing module (20) is arranged below the spray head lifting module (10) and comprises an adsorption platform; the adsorption platform is used for adsorbing and fixing the substrate; the spray head has three rectilinear motion freedom degrees of an X axis, a Y axis and a Z axis relative to the adsorption platform;

the first sensor (60) and the second sensor (50) are used for detecting the real-time distance between the nozzle and the substrate and the horizontal installation state of the nozzle and the adsorption platform; the first sensor (60) is arranged on the side of the spray head lifting module (10) and close to the spray nozzle, wherein the first sensor (60) emits sensing signals from top to bottom to pass through the plane of the adsorption platform and the upper surface of the substrate and generate first detection original signals; the second sensor (50) is arranged on the side of the adsorption platform and performs printing and scanning movement along the X-axis linear direction along with the adsorption platform; the second sensor (50) emits a sensing signal from bottom to top to pass through the surface of the nozzle and the lower surface of the substrate and generate a second detection original signal;

the sensor controller (40) is used for acquiring a first detection original signal and a second detection original signal, converting the signals into standard voltage signals after signal processing and correction operation, and sending the standard voltage signals to the motion driving controller (30);

the motion driving and controlling device (30) is used for acquiring and processing a standard voltage signal, calculating and establishing the height relation among the nozzle, the first sensor (60), the second sensor (50), the adsorption plane and the lifting mechanism, and therefore the lifting mechanism is controlled and driven in a fully closed loop mode.

2. The print height control system of claim 1, wherein the first sensor (60) and the second sensor (50) are both laser displacement sensors, mounted at a specific tilt angle, with the laser being incident on the detection object at normal incidence;

the first sensor (60) emits laser to the adsorption platform and the surface of the substrate from top to bottom, and when the lifting mechanism is positioned to the printing height measuring position, the detection range of the first sensor (60) covers the maximum substrate thickness;

the second sensor (50) emits laser to the surface of the nozzle and the lower surface of the substrate from bottom to top, and when the lifting mechanism is positioned to the printing height calibration position, the detection range of the second sensor (50) covers the surface of the nozzle and the lower surface of the substrate.

3. The print height control system according to claim 2, wherein the range of the first sensor (60) and the second sensor (50) is-L- + L, L>(d_max+H_max)/2；

Wherein d is_maxIs the maximum thickness of the substrate, H_maxAllowing the maximum print height for the system.

4. The print height control system of claim 1,

the first sensor (60) detects the horizontal installation state of the adsorption platform; the first sensor (60) moves relative to the adsorption platform along the X-Y plane direction, scans the adsorption platform, generates first height detection data along the X-Y plane direction, and adjusts the horizontal installation state of the adsorption platform according to the change trend of the first height detection data;

the second sensor (50) detects a horizontal installation state of the nozzle; the second sensor (50) moves relative to the spray head along the X-Y plane direction, scans the surface of the spray nozzle, generates second height detection data along the X-Y plane direction, and adjusts the spray head clamping device according to the change trend of the second height detection data, so that the horizontal installation state of the spray nozzle is adjusted.

5. The print height control system of claim 1,

when the system detects the printing height at the calibration position, the lifting mechanism is positioned at the calibration position, the second sensor (50) respectively detects the lower surface of the substrate and the surface of the nozzle, and the motion driving controller (30) calculates and obtains the height from the nozzle to the adsorption platform;

when the system is used for printing height zero marking at a measuring position, the lifting mechanism is positioned at the measuring position, the first sensors (60) respectively detect the adsorption table top, and the motion driving and controlling device (30) constructs the height relation among the nozzle, the first sensors (60), the second sensors (50), the adsorption plane and the lifting mechanism

When the system detects the printing height at the measuring position, the lifting mechanism is positioned at the measuring position, the substrate to be printed is placed on the adsorption platform, the first sensor (60) detects the distance from the nozzle to the surface of the printing substrate, and the motion driving and controlling device (30) acquires the current printing height based on the height relation between the nozzle, the first sensor (60), the second sensor (50), the adsorption plane and the lifting mechanism.

6. The print height control system according to claim 5, wherein the sensor controller (40) is provided with a first channel and a second channel, the first channel is used for acquiring a first detection raw signal, the second channel is used for acquiring a second detection raw signal, and the first and second detection raw signals are converted into standard voltage signals after signal processing and correction operation;

the correction operation is H ═ K · H + Δ H; wherein H is a correction measured value, H is an actual measured value, K is a correction coefficient, and Δ H is a correction constant.

7. The print height control system of claim 6,

a correction coefficient K ═ h of the first detected original signal correction operation_b-h_c)/(h_b1-h_c1) The correction constant Δ h ═ h_a1+h_b-h_a-(h_b-h_c)·h_b1/(h_b1-h_c1)；

When the lifting mechanism is respectively positioned at the positions a, b and c and the substrate is placed on the adsorption platform, the reading of the first sensor (60) is h_a1、h_b1And h_c1(ii) a Removing the substrate, the current first sensor (60) reading being h respectively_a、h_bAnd h_c；

A correction coefficient K ═ h of the second detected original signal correction operation_e-h_f)/(h_e1-h_f1) The correction constant Δ h ═ h_d1+h_e-h_d-(h_e-h_f)·h_e1/(h_e1-h_f1)；

When the lifting mechanism is respectively positioned at the positions d, e and f, the current reading of the second sensor (50) is h_d1、h_e1And h_f1The current readings of the first sensor (60) are h_d、h_eAnd h_f。

8. The printing height control system of claim 1, wherein the motion driver (30) drives the lifting mechanism in a cascade manner of outer ring height control and fully closed ring position control, thereby realizing automatic positioning of the printing height; wherein the content of the first and second substances,

after the system finishes the detection of the printing height at the measuring position, the external ring control input quantity is a printing height set value H 'and an actually measured height feedback value H, and the difference value delta H is calculated to be H' -H;

the output of the outer ring is a printing height deviation control variable_k＝K_p·(ΔH_k-ΔH_k-1) In which Δ H_kFor the currently measured deviation value, Δ H_k-1For the previous measurement of the deviation value, K_pIs a proportionality coefficient, K_p＝0.1·K_s～0.2·K_s，K_sRepresenting the position scaling factor in the position loop PID.

9. A print height control method for a print display, the method being performed based on the print height control system according to any one of claims 1 to 8, and comprising the steps of:

s1 nominal position print height detection:

placing the substrate on an adsorption platform and extending to the detection range of the second sensor (50), wherein the lower surface of the substrate is superposed with the adsorption platform, and reading the detection value h of the calibration sensor₁；

Removing the substrate, moving the nozzle relative to a second sensor (50) along the X-Y plane direction to enable the nozzle to be in the detection range of the second sensor (50), and positioning the lifting mechanism to a calibrated height pos₁A detected value h of a second sensor (50) for recording the current position₂；

Calculating the height from the nozzle to the adsorption platform: h is h₂-h₁；

S2 measurement position printing height zero:

the substrate is not placed on the adsorption platform, the nozzle moves relative to the first sensor (60) along the X-Y plane direction, so that the laser of the first sensor (60) irradiates on the adsorption platform surface, and the lifting mechanism is positioned to the measured height pos₂A detected value H of a second sensor 50 for recording the current position₁；

Constructing the height relation among the nozzle, the first sensor (60), the second sensor (50), the adsorption plane and the lifting mechanism: it is set that when the nozzle height is 0, the first sensor (60) reads H₁-h-pos₁-pos₂；

S3 measurement position print height detection:

placing the substrate to be printed on the adsorption platform and extending to the detection range of the second sensor (50), translating the nozzle relative to the second sensor (50) along the X-Y orientation to the measurement position in S2, and keeping the lifting mechanism positioned to the measurement height pos₂Record ofThe second sensor (50) detects a value H of the current position₂；

Reading the value H ═ H of the first sensor (60)₂-(H₁-h-pos₁-pos₂) When the lifting mechanism is positioned to a set printing height, a real-time detection value H of a first sensor (60) is input to the motion driving controller (30) as an actual measurement height feedback value to participate in height outer loop control;

s4 performs print height positioning:

setting the printing height set value to be H', starting outer ring cascade control by the motion driving controller (30), and measuring the height pos from S3 by the lifting mechanism₂And positioning to a set printing height position, closing the outer ring cascade control by the motion driving controller (30) after the positioning is finished, and keeping the position of the lifting mechanism at the printing height position by position closed-loop control.

10. A printer for a print display, comprising a print height control system as claimed in any one of claims 1 to 8.

Technical Field

The invention belongs to the technical field related to ink-jet printing, and particularly relates to a printing height control system and method for printing display.

Background

At present, the novel ink-jet printing technology is widely applied to the industrial manufacturing industry, and particularly, along with the manufacturing cost compression and efficiency requirements of the OLED panel, the OLED panel manufacturing process utilizing the ink-jet printing technology is a feasible method for reducing the production cost and improving the efficiency compared with the evaporation process, and the problems in the aspects of automation, precision control and reliability of a jet printing system need to be solved while the ink-jet printing process is gradually perfected. The special structure of the piezoelectric nozzle ensures that the nozzle surface of the nozzle is fragile and easy to pollute and block, and the printing height detection and accurate positioning are one of the difficulties to be solved. In terms of process requirements, the absolute distance from the nozzle face of the spray head to the panel substrate needs to be controlled and accurately adjusted, when the panel substrate is produced, the consistency and the repeatability of the printing height need to be ensured, the printing height exceeds an allowable error, the influence of the drop point deviation of ink drops is increased, and the yield is reduced.

The traditional printing height positioning method has two types: the method comprises the steps of (1) detecting and positioning a firing pin, and performing non-contact measurement and input substrate thickness positioning, wherein in a firing pin type detection mode, the firing pin, a spray nozzle of a spray head and a panel substrate can be contacted, and the spray nozzle of the spray head and the panel substrate are possibly damaged; the non-contact measurement widely adopts a laser displacement sensor, and the non-destructive measurement is solved, but the thickness of a panel substrate needs to be known, and the requirements of automation and safety protection cannot be met. Both methods lack solutions for automatic measurement and positioning, and accordingly, there is a strong need in the art to provide more appropriate solutions to meet the increasing technological requirements.

Disclosure of Invention

Aiming at the defects or improvement requirements of the prior art, the invention provides a printing height control system and a printing height control method for printing display, which are used for constructing the printing height control system, particularly for the combined arrangement of a calibration sensor (a second sensor) and a measurement sensor (a first sensor), constructing height or position relations of measurement values of various detection objects by a correction method, and performing high-precision positioning control on a lifting mechanism, so that the non-contact self-adaptive printing height positioning control is better realized, and the printing height control system and the printing height control method are particularly suitable for the requirements of high stability and high-precision printing process of OLED panel ink-jet printing.

To achieve the above object, a first aspect of the present invention provides a print height control system for a print display, which is used for inkjet printing of a panel substrate, and comprises: the device comprises a spray head lifting module, a substrate fixing module, a first sensor, a second sensor, a sensor controller and a motion driving controller;

the spray head lifting module comprises a spray head, a spray head clamping device and a lifting mechanism; the lower end of the spray head is provided with a spray nozzle, the spray head clamping device is used for fixing the spray head, and the lifting mechanism is connected with the spray head clamping device and is used for driving the spray head and the spray head clamping device to perform lifting movement, so that the printing height is positioned;

the substrate fixing module is arranged below the spray head lifting module and comprises an adsorption platform; the adsorption platform is used for adsorbing and fixing the substrate; the spray head has three rectilinear motion freedom degrees of an X axis, a Y axis and a Z axis relative to the adsorption platform;

the first sensor and the second sensor are used for detecting the real-time distance between the nozzle and the substrate and the horizontal installation state of the nozzle and the adsorption platform; the first sensor is arranged on the side of the spray head lifting module and close to the spray nozzle, and emits a sensing signal from top to bottom to pass through the plane of the adsorption platform and the upper surface of the substrate and generate a first detection original signal; the second sensor is arranged on the side of the adsorption platform and performs printing and scanning movement along the X-axis linear direction along with the adsorption platform; the second sensor emits a sensing signal from bottom to top to pass through the surface of the nozzle and the lower surface of the substrate and generate a second detection original signal;

the sensor controller is used for acquiring a first detection original signal and a second detection original signal, converting the signals into standard voltage signals after signal processing and correction operation, and sending the standard voltage signals to the motion driving and controlling device;

the motion driving and controlling device is used for acquiring and processing the standard voltage signal, calculating and establishing the height relation between the nozzle, the first sensor, the second sensor, the adsorption plane and the lifting mechanism, and therefore the lifting mechanism is controlled and driven in a fully closed loop mode.

Furthermore, the first sensor and the second sensor are both laser displacement sensors which are installed at a specific inclination angle, and laser is normally incident on a detection object;

the first sensor emits laser to the surfaces of the adsorption platform and the substrate from top to bottom, and when the lifting mechanism is positioned to the printing height measuring position, the detection range of the first sensor covers the maximum substrate thickness;

the second sensor emits laser on the surface of the nozzle and the lower surface of the substrate from bottom to top, and when the lifting mechanism is positioned to the printing height calibration position, the detection range of the second sensor covers the surface of the nozzle and the lower surface of the substrate.

Furthermore, the range of the first sensor and the second sensor is-L- + L, L>(d_max+H_max)/2；

Wherein d is_maxIs the maximum thickness of the substrate, H_maxAllowing the maximum print height for the system.

Further, the first sensor detects a horizontal installation state of the adsorption platform; the first sensor moves relative to the adsorption platform along the X-Y plane direction, scans the adsorption platform, generates first height detection data along the X-Y plane direction, and adjusts the horizontal installation state of the adsorption platform according to the variation trend of the first height detection data;

the second sensor detects a horizontal installation state of the nozzle; the second sensor moves relative to the spray head along the X-Y plane direction, scans the surface of the spray nozzle, generates second height detection data along the X-Y plane direction, and adjusts the spray head clamping device according to the change trend of the second height detection data, so that the horizontal installation state of the spray nozzle is adjusted.

Further, when the system detects the printing height at the calibration position, the lifting mechanism is positioned at the calibration position, the second sensor detects the lower surface of the substrate and the surface of the nozzle respectively, and the motion driving controller calculates and obtains the height from the nozzle to the adsorption platform;

when the system is used for printing height zero marking at a measuring position, the lifting mechanism is positioned at the measuring position, the first sensors respectively detect the adsorption table surfaces, and the motion driving and controlling device constructs the height relation among the nozzle, the first sensors, the second sensors, the adsorption plane and the lifting mechanism

When the system detects the printing height of the measuring position, the lifting mechanism is positioned at the measuring position, the substrate to be printed is placed on the adsorption platform, the first sensor detects the distance from the nozzle to the surface of the printing substrate, and the motion driving and controlling device acquires the current printing height based on the height relation between the nozzle, the first sensor, the second sensor, the adsorption plane and the lifting mechanism.

Further, the sensor controller is provided with a first channel and a second channel, the first channel is used for acquiring a first detection original signal, the second channel is used for acquiring a second detection original signal, and the first detection original signal and the second detection original signal are converted into standard voltage signals after signal processing and correction operation;

the correction operation is H ═ K · H + Δ H; wherein H is a correction measured value, H is an actual measured value, K is a correction coefficient, and Δ H is a correction constant.

Further, the correction coefficient K of the first detected original signal correction operation is (h)_b-h_c)/(h_b1-h_c1) The correction constant Δ h ═ h_a1+h_b-h_a-(h_b-h_c)·h_b1/(h_b1-h_c1)；

When the lifting mechanism is respectively positioned at the positions a, b and c and the substrate is placed on the adsorption platform, the reading of the first sensor is h_a1、h_b1And h_c1(ii) a Removing the substrate, wherein the current readings of the first sensors are h_a、h_bAnd h_c；

A correction coefficient K ═ h of the second detected original signal correction operation_e-h_f)/(h_e1-h_f1) The correction constant Δ h ═ h_d1+h_e-h_d-(h_e-h_f)·h_e1/(h_e1-h_f1)；

When the lifting mechanism is respectively positioned at the positions d, e and f, the current readings of the second sensor are respectively h_d1、h_e1And h_f1The current first sensor readings are respectively h_d、h_eAnd h_f。

Furthermore, the motion driving controller drives the lifting mechanism in a height outer ring control and position full closed ring cascade mode, so that the automatic positioning of the printing height is realized; wherein the content of the first and second substances,

after the system finishes the detection of the printing height at the measuring position, the external ring control input quantity is a printing height set value H 'and an actually measured height feedback value H, and the difference value delta H is calculated to be H' -H;

the output of the outer ring is a printing height deviation control variable_k＝K_p·(ΔH_k-ΔH_k-1) In which Δ H_kFor the currently measured deviation value, Δ H_k-1For the previous measurement of the deviation value, K_pIs a proportionality coefficient, K_p＝0.1·K_s～0.2·K_s，K_sRepresenting the position scaling factor in the position loop PID.

A second aspect of the present invention provides a print height control method for print display, characterized in that the method is executed based on the print height control system as described above, and comprises the steps of:

s1 nominal position print height detection:

placing the substrate on an adsorption platform and extending to the detection range of the second sensor, overlapping the lower surface of the substrate with the adsorption platform, and reading the detection value h of the calibration sensor₁；

Removing the substrate, moving the nozzle relative to a second sensor along the X-Y plane direction to enable the nozzle to be in the detection range of the second sensor, and positioning the lifting mechanism to a calibrated height pos₁Recording the second sensor detection value h of the current position₂；

Calculating the height from the nozzle to the adsorption platform: h is h₂-h₁；

S2 measurement position printing height zero:

the substrate is not placed on the adsorption platform, the nozzle moves relative to the first sensor along the X-Y plane direction, so that the laser of the first sensor irradiates on the adsorption platform surface, and the lifting mechanism is positioned to the measured height pos₂Recording the detected value H of the second sensor at the current position₁；

Constructing the height relation between the nozzle, the first sensor, the second sensor, the adsorption plane and the lifting mechanism: set the first sensor reading to be H when the nozzle height is 0₁-h-pos₁-pos₂；

S3 measurement position print height detection:

placing a substrate to be printed on the adsorption platform, extending the substrate to be printed into the detection range of the second sensor, translating the nozzle relative to the second sensor along the X-Y orientation to a measurement position in S2, and keeping the lifting mechanism positioned to a measurement height pos₂Recording the detected value H of the second sensor at the current position₂；

Reading a first sensor value H ═ H₂-(H₁-h-pos₁-pos₂) When the lifting mechanism is positioned to a set printing height, a real-time detection value H of a first sensor is input to the motion driving controller as an actually measured height feedback value to participate in height outer loop control;

s4 performs print height positioning:

let the printing height setThe fixed value is H', the motion driving controller starts the outer ring cascade control, and the lifting mechanism measures the height pos from S3₂And positioning to a set printing height position, closing the outer ring cascade control by the motion driving controller after positioning is finished, and keeping the position closed-loop control lifting mechanism at the printing height position.

A third aspect of the invention provides a print display oriented printer comprising a print height control system as described above.

Generally, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:

1. according to the printing height control system and method for printing display, provided by the invention, through reasonable arrangement of two sensors, non-contact measurement of a nozzle and a substrate of a spray head and a self-adaptive measurement method under unknown substrate thickness are realized, the automation degree of the system is improved, and errors generated by manual intervention are reduced;

2. the printing height control system and method for printing display, provided by the invention, can correct the measured values of various detection objects, and reduce the measurement errors caused by different differences of the colors, materials and surface states of the detection objects;

3. the printing height control system and method for printing display, provided by the invention, adopt a printing height positioning method of outer ring cascade control, and realize automatic and accurate positioning of the printing height according to the real-time height feedback of a detection sensor;

4. the printing height control system and method for printing display provided by the invention adopt the printing height online calibration method, use the working substrate as the calibration intermediate medium, do not need other auxiliary instruments, and have simple, rapid and reliable operation;

5. the printing height control system and method for printing display adopts a horizontal state detection and adjustment method of a nozzle surface of a spray head and an adsorption surface of a substrate, measures two-dimensional distance distribution of the two surfaces through a detection sensor, respectively adjusts the horizontal state of a single surface based on real-time data, achieves the parallelism of the nozzle surface of the spray head and the adsorption surface of the substrate within a reasonable range, realizes the consistency of the printing height in the motion printing process, and effectively reduces the positioning deviation of ink drops;

6. according to the printing height control system and method for printing display, provided by the invention, the safe printing height of the nozzle of the spray head is set, and an anti-collision processing and early warning mechanism is utilized, so that the anti-collision protection of the nozzle of the spray head is effectively realized, and the production cost is saved.

Drawings

FIG. 1 is a schematic diagram of a print height control system for a print display implemented in accordance with the present invention;

FIG. 2 is a schematic diagram of the principle of correction of measured values of various inspection objects of a print-display-oriented print height control system implemented in accordance with the present invention;

FIG. 3 is a schematic diagram of the print height positioning control principle of a print display oriented print height control system implemented in accordance with the present invention;

FIG. 4 is a schematic flow diagram of a print height control method for a print display implemented in accordance with the present invention;

FIG. 5 is a schematic diagram of a nominal position print height detection for a print display oriented print height control method implemented in accordance with the present invention;

FIG. 6 is a schematic diagram of a measured position print height zero for a print display oriented print height control method implemented in accordance with the present invention;

FIG. 7 is a nozzle collision avoidance flow diagram of a print height control method for a print display implemented in accordance with the present invention;

in the figure: the device comprises a spray head lifting module-10, a substrate fixing module-20, a motion driver-30, a sensor controller-40, a second sensor-50 and a first sensor-60.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

It should be noted that the term "first \ second" referred to in the present invention is only used for distinguishing similar objects, and does not represent a specific ordering for the objects, and it should be understood that "first \ second" may be interchanged in a specific order or sequence, if allowed. It should be understood that "first \ second" distinct objects may be interchanged under appropriate circumstances such that embodiments of the invention described herein may be practiced in sequences other than those described or illustrated herein.

It should be noted that in the functional equations of the present invention, the symbol "·" is an operation symbol representing the multiplication of two constants or vectors before and after, and "/" is an operation symbol representing the division of two constants or vectors before and after, and all the functional equations of the present invention follow the mathematical operation of addition, subtraction, multiplication and division.

As shown in fig. 1, the present invention provides a print height control system for print display, which is used for inkjet printing of a panel substrate, and comprises: the substrate fixing apparatus includes a head lifting module 10, a substrate fixing module 20, a first sensor 60, a second sensor 50, a sensor controller 40, and a motion driver 30; the spray head lifting module 10 comprises a spray head, a spray head clamping device and a lifting mechanism; the lower end of the spray head is provided with a spray nozzle, the spray head clamping device is used for fixing the spray head, and the lifting mechanism is connected with the spray head clamping device and is used for driving the spray head and the spray head clamping device to perform lifting movement, so that the printing height is positioned; the substrate fixing module 20 is arranged below the nozzle lifting module 10 and comprises an adsorption platform; the adsorption platform is used for adsorbing and fixing the substrate; the spray head has three rectilinear motion freedom degrees of an X axis, a Y axis and a Z axis relative to the adsorption platform; the first sensor 60 and the second sensor 50 are used for detecting the real-time distance between the nozzle and the substrate and the horizontal installation state of the nozzle and the adsorption platform; the first sensor 60 is arranged at the side of the spray head lifting module 10 and close to the spray nozzle, wherein the first sensor 60 emits a sensing signal from top to bottom to pass through the plane of the adsorption platform and the upper surface of the substrate and generate a first detection original signal; the second sensor 50 is arranged at the side of the adsorption platform and performs printing and scanning movement along the X-axis linear direction along with the adsorption platform; the second sensor 50 emits a sensing signal from bottom to top through the nozzle surface and the lower surface of the substrate, and generates a second detection original signal; the sensor controller 40 is used for acquiring the first and second detection original signals, converting the signals into standard voltage signals after signal processing and correction operation, and sending the standard voltage signals to the motion driving and controlling device 30; the motion driving and controlling device 30 is used for acquiring and processing the standard voltage signal, performing calculation, and establishing the height relationship between the nozzle, the first sensor 60, the second sensor 50, the adsorption plane and the lifting mechanism, so as to perform full closed-loop control and driving on the lifting mechanism.

Further, the first sensor 60 and the second sensor 50 are both laser displacement sensors, and are installed at a specific inclination angle, and the laser is normally incident on the detection object; the first sensor 60 emits laser on the adsorption platform and the surface of the substrate from top to bottom, and when the lifting mechanism is positioned to the printing height measuring position, the detection range of the first sensor 60 covers the maximum substrate thickness; the second sensor 50 emits laser on the surface of the nozzle and the lower surface of the substrate from bottom to top, and when the lifting mechanism is positioned to the printing height calibration position, the detection range of the second sensor 50 covers the surface of the nozzle and the lower surface of the substrate.

Furthermore, the range of the first sensor 60 and the second sensor 50 is-L- + L, L>(d_max+H_max) 2; wherein d is_maxIs the maximum thickness of the substrate, H_maxAllowing the maximum print height for the system.

Further, the first sensor 60 detects the horizontal installation state of the adsorption platform; the first sensor 60 moves along the X-Y plane direction relative to the adsorption platform, scans the adsorption platform, generates first height detection data along the X-Y plane direction, and adjusts the horizontal installation state of the adsorption platform according to the variation trend of the first height detection data; the second sensor 50 detects the horizontal installation state of the nozzle; the second sensor 50 moves along the X-Y plane direction relative to the nozzle and scans the surface of the nozzle to generate second height detection data along the X-Y plane direction, and the nozzle clamping device is adjusted according to the change trend of the second height detection data, so that the horizontal installation state of the nozzle is adjusted.

Further, when the system performs printing height detection at the calibration position, the lifting mechanism is positioned at the calibration position, the second sensor 50 detects the lower surface of the substrate and the surface of the nozzle respectively, and the motion drive controller 30 calculates and acquires the height from the nozzle to the adsorption platform; when the system prints height mark zero at the measuring position, the lifting mechanism is positioned at the measuring position, the first sensor 60 detects the adsorption table surface respectively, and the motion drive controller 30 constructs the height relation among the nozzle, the first sensor 60, the second sensor 50, the adsorption plane and the lifting mechanism; when the system detects the printing height at the measuring position, the lifting mechanism is positioned at the measuring position, the substrate to be printed is placed on the adsorption platform, the first sensor 60 detects the distance from the nozzle to the surface of the substrate to be printed, and the motion drive controller 30 acquires the current printing height based on the height relation between the nozzle, the first sensor 60, the second sensor 50, the adsorption plane and the lifting mechanism.

As shown in fig. 2, in the present invention, the sensor controller 40 is provided with a first channel and a second channel, the first channel is used for acquiring a first original detection signal, the second channel is used for acquiring a second original detection signal, and the first original detection signal and the second original detection signal are converted into standard voltage signals after signal processing and correction operation; the correction operation is H ═ K · H + Δ H; the correction operation corrects the first detection original signal and the second detection original signal, wherein H is a correction measurement value, H is an actual measurement value, K is a correction coefficient, and Δ H is a correction constant, namely, the readings of the first sensor and the second sensor which are detection objects of the substrate and the nozzle are corrected respectively, and the specific correction parameter is calculated and derived as follows:

(1) for substrate detection, i.e. correcting the first original detection signal, the first sensor 60 emits the sensing signal from top to bottom through the plane of the adsorption platform and the upper surface of the substrate, and generates the first original detection signal, and the establishment process of the correction equation is as follows: when the lifting mechanism is positioned at the position a, when the adsorption platform is used for placing the substrate and not used for placing the substrate, the reading numbers of the measuring sensors (the first sensor 60) are respectively h_a1And h_a(ii) a When the lifting mechanism is at the position b, the readings of the two states are h_b1And h_b(ii) a When the lifting mechanism is at the position c, the readings of the two states are h_c1And h_cAnd solving the substrate detection correction value by the following formula:

K＝(h_b-h_c)/(h_b1-h_c1)

Δh＝h_a1+h_b-h_a-(h_b-h_c)·h_b1/(h_b1-h_c1)

(2) for nozzle detection, i.e. correcting the second original detection signal, the second sensor 50 emits the sensing signal from bottom to top through the nozzle surface and the lower substrate surface and generates the second original detection signal, and the establishment process of the correction equation is as follows: when the elevating mechanism is positioned at the position d, the calibration sensor (second sensor 50) detects that the nozzle reading is h_d1The measuring sensor (first sensor 60) detects that the reading of the adsorption platform is h_d(ii) a When the lifting mechanism is positioned at the e position, the readings of the two states are h_e1And h_e(ii) a When the lifting mechanism is at the f position, the readings of the two states are h_f1And h_fAnd solving the nozzle detection correction value by the following formula:

K＝(h_e-h_f)/(h_e1-h_f1)

Δh＝h_d1+h_e-h_d-(h_e-h_f)·h_e1/(h_e1-h_f1)

the positions of the lifting mechanisms a, b and c and the positions d, e and f respectively satisfy the vicinity of the maximum value, the middle value and the minimum value of the laser sensor range, and the corrected position covers the full range of the laser sensor.

As shown in fig. 3, in the present invention, the movement driver 30 drives the lifting mechanism in a manner of height outer ring control and position full closed ring cascade, so as to realize automatic positioning of the printing height; after the system finishes detecting the printing height at the measuring position, the outer ring control input quantity is a printing height set value H 'and an actually measured height feedback value H, and the difference value delta H is calculated to be H' -H; the difference value of the measurement deviation output by the outer ring is amplified and output to print height deviation control variable through PID proportional operation_k＝K_p·(ΔH_k-ΔH_k-1) Parameter of_kThe value reflects the weight ratio of the outer ring in the position closed-loop control, and influences the positioning response speed of the lifting mechanism, wherein deltaH_kRepresenting the current measured deviation value, Δ H_k-1 represents the value of the deviation of the previous measurement, K_pIs a proportionality coefficient, K_p＝0.1K_s～0.2K_s，K_sRepresenting the position scaling factor in the position loop PID.

As shown in fig. 4, the present invention provides a print height control method for print display, which is executed based on the print height control system as described above and includes the following steps:

s1 nominal position print height detection:

placing the substrate on the adsorption platform and extending to the detection range of the second sensor 50, superposing the lower surface of the substrate and the adsorption platform, and reading the detection value h of the calibration sensor₁；

Removing the substrate, moving the nozzle relative to the second sensor 50 along the X-Y plane direction to make the nozzle within the detection range of the second sensor 50, and positioning the lifting mechanism to the calibrated height pos₁The detected value h of the second sensor 50 for recording the current position₂；

Calculating the height from the nozzle to the adsorption platform: h is h₂-h₁；

S2 measurement position printing height zero:

the substrate is not placed on the adsorption platform, the nozzle is moved relative to the first sensor 60 along the X-Y plane direction, so that the laser of the first sensor 60 irradiates on the adsorption platform surface, and the lifting mechanism is positioned to the measurement height pos₂The detected value H of the second sensor 50 for recording the current position₁；

Constructing the height relationship of the nozzle, the first sensor 60, the second sensor 50, the adsorption plane and the lifting mechanism: it is assumed that when the nozzle height is 0, the first sensor 60 reads H₁-h-pos₁-pos₂；

S3 measurement position print height detection:

placing the substrate to be printed on the adsorption platform and extending to the second sensorTranslating the nozzle relative to the second sensor 50 along the X-Y orientation to the measurement position in S2 within the detection range of the device 50, and keeping the lifting mechanism positioned to the measurement height pos₂The detected value H of the second sensor 50 for recording the current position₂；

Reading the value H-H of the first sensor 60₂-(H₁-h-pos₁-pos₂) When the lifting mechanism is positioned to the set printing height, the real-time detection value H of the first sensor 60 is input to the motion drive controller 30 as an actual measurement height feedback value to participate in height outer loop control;

s4 performs print height positioning:

let the printing height setting value be H', the motion driver 30 starts the outer ring cascade control, and the elevating mechanism measures the height pos from S3₂And positioning to a set printing height position, closing the outer ring cascade control by the motion driving and controlling device 30 after positioning is finished, and keeping the position closed-loop control lifting mechanism at the printing height position.

The invention provides a printing height control system and a method facing printing display, which can better realize non-contact self-adaptive printing height positioning control by constructing a printing height control system, particularly by combining and arranging a calibration sensor and a measurement sensor, constructing height or position relation for measurement values of various detection objects by a correction method, and carrying out high-precision positioning control on a lifting mechanism.

A specific embodiment of the present invention provides a print height control system for print display, as shown in fig. 1, which includes six parts including: the substrate fixing apparatus includes a head lifting module 10, a substrate fixing module 20, a first sensor 60, a second sensor 50, a sensor controller 40, and a motion driver 30; the first sensor 60 is a measurement sensor, and the second sensor 50 is a calibration sensor.

Further, the nozzle lifting module 10 includes a nozzle, a nozzle clamping device and a lifting mechanism, wherein the nozzle clamping device is used for fixing the nozzle. The substrate fixing module 20 includes a substrate and an adsorption platform, wherein the substrate is a reference and an object to be printed, the substrate is adsorbed on the adsorption platform during printing, and the nozzle has three rectilinear motion degrees of freedom of X/Y/Z relative to the adsorption platform. The motion driving controller 30 is used for full closed-loop control and driving of the lifting mechanism, and meanwhile, sensor signals are processed, and an operation model and automatic flow control are constructed; the sensor controller 40 is used for collecting and processing the raw signals detected by the calibration sensor (the second sensor 50) and the measurement sensor (the first sensor 60), and the raw signals are converted into standard voltage signals after signal processing and correction operation and are provided for the motion controller 30.

Furthermore, in the position full closed-loop control, the change of a motion terminal directly measured by a position feedback element is different from semi-closed-loop control and open-loop control, the position feedback element in the semi-closed-loop control adopts a motor encoder, the measured value can introduce errors of a transmission system, and the open-loop control has no feedback element. In the system, a feedback element is a grating, and a laser displacement sensor is additionally introduced to directly measure the position and height changes.

Further, a calibration sensor (a second sensor 50) is used for calibrating the absolute distance between the nozzle and the adsorption platform when the lifting mechanism is at a specific measurement position, and is also used for detecting the horizontal installation state of the nozzle; the calibration sensor (the second sensor 50) and the measurement sensor (the first sensor 60) are used for detecting the real-time distance between the nozzle and the substrate to be printed and simultaneously detecting the installation horizontal state of the adsorption platform. The calibration sensor (the second sensor 50) and the measurement sensor (the first sensor 60) both adopt laser displacement sensors, are installed at specific inclination angles, and are used for detecting an object under normal incidence of laser, wherein the calibration sensor (the second sensor 50) is fixed on the side of the adsorption platform and moves in X-direction printing and scanning together with the adsorption platform, the calibration sensor (the second sensor 50) emits laser from bottom to top to detect the surface of a nozzle and the lower surface of a substrate, and when the lifting mechanism is at a printing height calibration position, the detection amount range of the calibration sensor (the second sensor 50) covers the nozzle and the lower surface of the substrate; the measuring sensor (first sensor 60) is arranged on the lifting mechanism, the laser is emitted from top to bottom to detect the adsorption platform and the substrate on the adsorption platform, and when the lifting mechanism prints the height measuring position, the detection range of the measuring sensor (first sensor 60) covers the maximum substrate thickness required by the process.

Further, the accuracy, range, mounting and detection position of the laser displacement sensor directly affect the measurement accuracy of the printing height when the maximum thickness d of the substrate is reached_maxProcess requires a process-allowed maximum print height H_maxWhen the range of the laser displacement sensor is-L- + L, the range of the laser sensor meets L>(d_max+H_max)/2. When d is_max＝2mm，H_maxThe substrate is preferably selected to have a range of 2mm<L<3.5, the safety range is reserved on the premise of meeting the precision requirement, preferably, the range of the laser displacement sensor is 3mm, the measuring position of the calibration sensor (second sensor 50) is met, when the nozzle reaches 1mm of the surface of the adsorption platform, the distance measuring value of the detection nozzle of the calibration sensor (second sensor 50) is 1-2 mm, the measuring position of the measuring sensor (first sensor 60) is met, and when the nozzle reaches 1mm of the surface of the adsorption platform, the distance measuring value of the adsorption platform, namely-2-1 mm, is detected by the measuring sensor (first sensor 60).

Further, before the system detects the printing height at the calibration position, the parallelism between the nozzle and the substrate adsorption platform needs to be calibrated. The calibration sensor (a second sensor 50) detects the horizontal installation state of the nozzle, the calibration sensor (the second sensor 50) moves along the X-Y plane direction relative to the nozzle and scans the surface of the nozzle to generate second height detection data along the X-Y plane direction, and the nozzle clamping device is adjusted according to the change trend of the second height detection data, so that the horizontal installation state of the nozzle is adjusted; similarly, the measuring sensor (the first sensor 60) detects the horizontal state of the adsorption platform, the measuring sensor (the first sensor 60) moves along the X-Y plane direction relative to the adsorption platform and scans the adsorption platform to generate first height detection data along the X-Y plane direction, and the horizontal installation state of the adsorption platform is adjusted according to the variation trend of the first height detection data.

Fig. 2 is a schematic diagram of a method for correcting measured values among a plurality of detection objects according to an embodiment of the present invention. The sensor controller collects signals collected by a calibration sensor (a second sensor 50) and a measurement sensor (a first sensor 60) for two channels respectively, the sensor controller 40 is provided with a first channel and a second channel, the first channel is used for acquiring a first detection original signal, the second channel is used for acquiring a second detection original signal, and the first detection original signal and the second detection original signal are converted into standard voltage signals after signal processing and correction operation; the collected signals are processed by a signal processing and conversion formula, and the corrected measured value is output and transmitted to the motion controller, wherein the selection of the conversion formula is judged by the motion controller according to the detection object program, and an instruction is sent to the sensor controller. The adsorption platform is used as a standard object detection template, the original measurement value is directly transmitted after signal processing, and when the detection object is a substrate or a nozzle, the transmitted measurement value is a correction value solved by a conversion formula. A correction equation is established for each of the substrate and the nozzle as an object to be inspected, and the expression is H-K.h + Δ H, where H is a measurement correction value when the substrate or the nozzle is the object to be inspected, H is an actual measurement value when the substrate or the nozzle is the object to be inspected, K is a correction coefficient, and Δ H is a correction constant. The correction operation corrects the first detection original signal and the second detection original signal, namely, corrects the readings of the first sensor and the second sensor which are detection objects of the substrate and the nozzle respectively, and the specific correction parameters are derived as follows:

further, for substrate detection, i.e. correcting the first original detection signal, the first sensor 60 emits the sensing signal from top to bottom through the plane of the adsorption platform and the upper surface of the substrate, and generates the first original detection signal, and the establishment process of the correction equation is as follows: when the lifting mechanism is positioned at the position a, when the adsorption platform is used for placing the substrate and not used for placing the substrate, the reading numbers of the measuring sensors (the first sensor 60) are respectively h_a1And h_a(ii) a When the lifting mechanism is at the position b, the readings of the two states are h_b1And h_b(ii) a When the lifting mechanism is at the position c, the readings of the two states are h_c1And h_cAnd solving the substrate detection correction value by the following formula:

K＝(h_b-h_c)/(h_b1-h_c1)

Δh＝h_a1+h_b-h_a-(h_b-h_c)·h_b1/(h_b1-h_c1)

further, for nozzle detectionThat is, for the second original detection signal, the second sensor 50 emits the sensing signal from bottom to top through the nozzle surface and the lower substrate surface, and generates the second original detection signal, and the establishment process of the correction equation is as follows: when the elevating mechanism is positioned at the position d, the calibration sensor (second sensor 50) detects that the nozzle reading is h_d1The measuring sensor (first sensor 60) detects that the reading of the adsorption platform is h_d(ii) a When the lifting mechanism is positioned at the e position, the readings of the two states are h_e1And h_e(ii) a When the lifting mechanism is at the f position, the readings of the two states are h_f1And h_fAnd solving the nozzle detection correction value by the following formula:

K＝(h_e-h_f)/(h_e1-h_f1)

Δh＝h_d1+h_e-h_d-(h_e-h_f)·h_e1/(h_e1-h_f1)

the positions of the lifting mechanisms a, b and c and the positions d, e and f respectively satisfy the vicinity of the maximum value, the middle value and the minimum value of the laser sensor range, and the corrected position covers the full range of the laser sensor.

FIG. 3 is a schematic diagram of a printing height positioning control principle implemented according to an embodiment of the present invention, in which a lifting mechanism introduces a height outer loop control based on a position closed loop, an outer loop output control quantity participates in the position closed loop control as one deviation quantity of a position loop, and automatic positioning of a set printing height is implemented in a cascade mode of an outer loop and a position full closed loop, the cascade mode takes effect only after detection of a measured position is completed, the lifting mechanism is terminated after being positioned at the set printing height, and the automatic positioning is controlled by a cascade switch inside a motion drive controller; the outer ring control input quantity is printing height set value H 'and measured height feedback value H, the difference value delta H is H' -H, the difference value of the measured deviation output by the outer ring is amplified by proportional operation to output printing height deviation control variable_k＝K_p·(ΔH_k-ΔH_k-1) Parameter of_kThe value reflects the weight ratio of the outer ring in the position closed-loop control, and influences the positioning response speed of the lifting mechanism, wherein deltaH_kRepresenting the current measured deviation value, Δ H_k-1 represents the previous measurementDeviation value of measurement, K_pIs a proportionality coefficient, K_p＝0.1K_s～0.2K_s，K_sRepresenting the position scaling factor in the position loop PID.

Further, the laser interferometer calibrates the working stroke of the lifting mechanism, and when the position is measured, the position input value of the motion driving controller is POS₂The printing height deviation control variable is mapped by a dynamic error compensation table and is output with a position feedback value P and an outer ring_kTogether as a position loop PID control input control quantity.

FIG. 4 is a flow chart of a printing height control method implemented according to an embodiment of the present invention, which is divided into four steps:

the first step, marking position and printing height detection:

as shown in fig. 5, the substrate is placed on the adsorption platform and extends into the detection range of the calibration sensor (the second sensor 50), and at this time, the lower surface of the substrate coincides with the adsorption platform, and the detection value h of the calibration sensor (the second sensor 50) is read₁The substrate is removed, the nozzle is translated in XY direction relative to the calibration sensor (second sensor 50) so that the nozzle is in the detection range of the calibration sensor (second sensor 50), and the lifting mechanism is positioned to the calibration height POS₁Recording the detected value h of the reference sensor (second sensor 50) at the position₂At this time, when the height is calibrated, the height from the nozzle to the adsorption platform is h ═ h₂-h₁；

The second step, measuring the printing height mark zero:

referring to fig. 6, the substrate is not placed on the adsorption stage, the nozzle is translated in the XY direction relative to the adsorption stage, the laser beam from the measurement sensor (first sensor 60) is irradiated on the adsorption stage, and the lift mechanism is positioned to the measurement height pos₂Recording the measured value H₁Establishing the following relation model: when the nozzle height is 0, the measurement sensor (first sensor 60) reads H₁-h-pos₁-pos₂；

A third step of measuring the printing height of the measuring position:

placing the substrate to be printed in the working area of the adsorption platform, and moving the adsorption platform and the nozzle in the XY direction to the measurement position in the second stepThe lifting mechanism is kept at the measuring height, and the value H of the measuring sensor (the first sensor 60) is read₂And obtaining the printing height H ═ H at the moment through the step two relation model₂-(H₁-h-pos₁-pos₂) In the process that the lifting mechanism is positioned to the set printing height, the real-time detection value H of the measuring sensor (the first sensor 60) is used as height feedback to participate in outer loop control;

a fourth step of performing printing height positioning:

setting the printing height to be H', starting outer ring cascade control, positioning the lifting mechanism to the set printing height position from the height measured in the third step, closing the outer ring cascade after positioning, and keeping the position of the lifting mechanism at the printing height position under position closed-loop control.

FIG. 7 shows a nozzle crash flow diagram for calculating the maximum travel of the lift mechanism using a relational model with safe print height settings for the nozzles, in accordance with a preferred embodiment of the present invention; the method comprises the following steps that in the first condition, when in an automatic printing state, a printing height setting frame prohibits inputting a numerical value which is larger than a safe height value, and misoperation is avoided from an input end; in the second case, in the manual or debug state, the position of the lifting mechanism is cyclically detected and judged in the PLC program (electronic system operated by digital operation) and is greater than the corresponding threshold value of the safe printing height, and the system gives an alarm and disables the movement of the lifting mechanism.

The embodiment of the invention also provides a readable storage medium, wherein an operation program is stored on the readable storage medium, and the operation program can be processed and executed to realize the printing height control method for printing display.

It should be understood that any process or method descriptions of methods, structures, or steps described herein in a block diagram or otherwise may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and that the scope of the preferred embodiments of the present invention includes additional implementations in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present invention.

It should be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the various steps or methods may be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.

It will be understood by those skilled in the art that all or part of the steps carried by the method for implementing the above embodiments may be implemented by hardware related to instructions of a program, which may be stored in a computer readable storage medium, and when the program is executed, the program includes one or a combination of the steps of the method embodiments.

In addition, functional units in the embodiments of the present invention may be integrated into one processing module, or each unit may exist alone physically, or two or more units are integrated into one module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. The integrated module, if implemented in the form of a software functional module and sold or used as a stand-alone product, may also be stored in a computer readable storage medium.

The storage medium mentioned above may be a read-only memory, a magnetic or optical disk, etc.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art without departing from the principle and spirit of the present invention. The scope of the invention is defined by the appended claims and equivalents thereof.