阅读说明：本技术 一种高效率旋转扫描平面成像装置及方法 (High-efficiency rotary scanning plane imaging device and method ) 是由 俞红祥 庞伟 何雪军 王康恒 朱莹莹 于 2019-12-10 设计创作，主要内容包括：本发明涉及一种高效率旋转扫描平面成像装置及方法,包括直线模组,直线模组的移动平台上有刚性支架,刚性支架上设有转镜电机、激光器,转镜电机输出轴与多面反射镜的中心孔紧密配合,多面反射镜的圆周等分分布多个反射面,转镜电机可带动多面反射镜连续旋转；激光器射出的激光束,相对多面反射镜正截面并倾斜指向多面反射镜的中轴线,所形成的反射光束在直线模组上方的成像面上形成光斑；转镜电机带动多面反射镜连续旋转时,反射光束被多个反射面顺序偏转,使得光斑在成像面上往复扫描生成弯曲扫描线；成像面上方设有图像传感器,用于将弯曲扫描线转换为数字化像素图,以确定弯曲扫描线中各投射像素在矩形成像区域中的行列位置。本发明光路简单、激光束能量损失小,最大光学扫描角接近2倍反射面圆周分度角,并能有效解决扫描线枕形畸变对成像精度影响。(The invention relates to a high-efficiency rotary scanning plane imaging device and a method, comprising a linear module, wherein a moving platform of the linear module is provided with a rigid support, the rigid support is provided with a rotating mirror motor and a laser, an output shaft of the rotating mirror motor is tightly matched with a central hole of a multi-surface reflector, the circumference of the multi-surface reflector is equally distributed with a plurality of reflecting surfaces, and the rotating mirror motor can drive the multi-surface reflector to continuously rotate; the laser beam emitted by the laser is obliquely directed to the central axis of the multi-surface reflector relative to the normal section of the multi-surface reflector, and the formed reflected beam forms a light spot on an imaging surface above the linear module; when the rotating mirror motor drives the multi-surface reflector to continuously rotate, the reflected light beams are sequentially deflected by the plurality of reflecting surfaces, so that the light spots are scanned on the imaging surface in a reciprocating manner to generate curved scanning lines; an image sensor is arranged above the imaging surface and used for converting the bent scanning lines into a digital pixel map so as to determine the row and column positions of the projection pixels in the bent scanning lines in the rectangular imaging area. The invention has simple light path and small energy loss of laser beams, the maximum optical scanning angle is close to 2 times of the circumferential dividing angle of the reflecting surface, and the influence of scanning line pincushion distortion on the imaging precision can be effectively solved.)

1. The utility model provides a high efficiency rotation scanning plane image device, includes sharp module (1), characterized by: a rigid support (2) is arranged on a moving platform of the linear module (1), a rotating mirror motor (3) and a laser (4) are arranged on the rigid support (2), an output shaft of the rotating mirror motor (3) is tightly matched with a central hole of a multi-surface reflector (5), a plurality of reflecting surfaces are equally distributed on the circumference of the multi-surface reflector (5), and the rotating mirror motor (3) can drive the multi-surface reflector (5) to continuously rotate; a laser beam (41) emitted by the laser (4) is opposite to the normal section of the multi-surface reflector (5) and obliquely points to the central axis of the multi-surface reflector (5), and a formed reflected beam (42) forms a light spot (61) on an imaging surface (6) above the linear module (1); when the rotating mirror motor (3) drives the multi-surface reflecting mirror (5) to continuously rotate, the reflected light beam (42) is sequentially deflected by a plurality of reflecting surfaces, so that the light spot (61) is scanned to and fro on the imaging surface (6) to generate a curved scanning line (62); an image sensor (7) is arranged above the imaging surface (6) and is used for converting the curved scanning lines (62) into a digital pixel map so as to determine the row and column positions of the projected pixels in the curved scanning lines (62) in the rectangular imaging area (63).

2. A high efficiency rotary scan plane imaging device as claimed in claim 1, wherein: three reflecting surfaces are equally distributed on the circumference of the multi-surface reflector (5).

3. A high efficiency rotary scan plane imaging device as claimed in claim 1 or 2, wherein: the scanning controller (100) is respectively connected with the linear module (1), the rotating mirror motor (3), the laser (4) and the image sensor (7).

4. A high efficiency rotary scan plane imaging device as claimed in claim 3, wherein: the scanning controller (100) is internally provided with a first decoder module (101), a second decoder module (102), a row scanning control module (103), a column scanning control module (104), a row-column correction module (105) and a laser control module (106), the rotating mirror motor (3) is connected with the first decoder module (101), the first decoder module (101) is connected with the row scanning control module (103), the linear module (1) is connected with the second decoder module (102), the second decoder module (102) is connected with the column scanning control module (104), the row scanning control module (103) and the column scanning control module (104) are connected with the row-column correction module (105), the row-column correction module (105) is connected with the laser control module (106), and the laser control module (106) is connected with the laser (4).

5. A method of high efficiency rotational scan plane imaging using the apparatus of claim 3, characterized by: the linear module (1) drives a multi-surface reflector rotary scanning device which is formed by combining a rigid support (2), a rotating mirror motor (3), a laser (4) and a multi-surface reflector (5) to move from a scanning starting line to a scanning ending line; during the movement of the linear module (1), curved scanning lines (62) projected by the multi-surface reflector (5) are arranged line by line on the imaging surface (6) along the movement direction of the linear module (1) to form a scanning area (64); when the linear module (1) continues to move and reaches the scanning termination line, the scanning area (64) also expands forwards along the movement of the linear module (1) until the rectangular imaging area (63) of the imaging surface (6) is completely covered; when instantaneous imaging pixels in the curved scanning line (62) are positioned in the rectangular imaging area (63) in the moving process of the linear module (1), the scanning controller (100) outputs pixel gray values of the corresponding position of the current scanning plane image as brightness control signals of the laser (4), so that the brightness of each imaging pixel in the rectangular imaging area (63) is consistent with that of the plane image.

Technical Field

The invention relates to the field of three-dimensional printers, in particular to a high-efficiency rotary scanning plane imaging device and method.

Background

The traditional multi-facet mirror rotary scanning device generally adopts a normal-section incident light path in order to eliminate pincushion distortion of a scanning line on a plane imaging surface, the pincushion distortion is derived from a deflection reflection structure of the multi-facet mirror, when an incident light beam and the normal section of the mirror form an included angle α, an imaging light spot has a projection height h relative to the normal section of the incident point when a reflected light beam reaches the imaging surface, and h is a product of a reflection light path d and a sine function value of an included angle α, because the reflection light path d changes along with the deflection of the multi-facet mirror, the imaging light spot scanning line presents a central symmetry pincushion bending form on the plane imaging surface, only when α is zero, namely, the imaging light spot scanning line is a straight line, but in practice, the adoption of the normal-section incident light path easily causes interference between a light source and the plane imaging surface of the multi-facet mirror, and the effective scanning window power limitation of the multi-facet mirror is caused by the fact that the reflected light spot scanning beam is restricted.

In recent years, the rapidly developed additive technology promotes ultraviolet laser scanning imaging devices with wavelengths of 355nm to 405nm to be widely applied to various types of photocuring three-dimensional printers. The most common is a galvanometer type two-axis linkage scanning galvanometer, the vector scanning mode of the galvanometer type two-axis linkage scanning galvanometer has high utilization rate of the nominal power of a laser, but when complex graphs are processed, the average scanning linear velocity can be greatly reduced by frequent vector turning and idle trip jumping, so that the high-speed printing of complex parts is difficult to realize. Recently, patent documents and media data disclose photocuring three-dimensional printing technologies based on micro-electromechanical system (MEMS) high-speed micro-galvanometer and multi-surface mirror rotary scanning devices, but the printing precision and precision stability of the former need to be improved, while the problem of low laser utilization efficiency of the latter still exists, and especially the occupation ratio of the ultraviolet laser in the total cost of the photocuring three-dimensional printer is high for a long time, so that the cost-efficiency ratio of the whole machine is low. Technical schemes for correcting pincushion distortion and improving the utilization efficiency of a laser by adopting a multi-reflection optical path are also reported, but the problems of complex optical path structure and energy loss caused by multi-reflection of a laser beam are urgently solved. At present, aiming at the urgent need of further improving the utilization efficiency of a laser, in the field of laser scanning imaging, a high-efficiency rotary scanning plane imaging method which is simple in light path, small in energy loss of laser beams, wide in scanning window and capable of effectively solving the problem of influence of pincushion distortion of scanning lines on imaging precision is still lacking.

Disclosure of Invention

The invention aims to solve the defects of the prior art and provides a high-efficiency rotary scanning plane imaging device and a high-efficiency rotary scanning plane imaging method which have the advantages of simple optical path, small energy loss of laser beams, 2 times of maximum optical scanning angle of the circumference division angle of the reflecting surface and capability of effectively solving the influence of pincushion distortion of scanning lines on imaging precision.

The invention adopts the technical scheme for solving the technical problems that: the high-efficiency rotary scanning plane imaging device comprises a linear module, wherein a rigid support is arranged on a moving platform of the linear module, a rotating mirror motor and a laser are arranged on the rigid support, an output shaft of the rotating mirror motor is tightly matched with a central hole of a multi-surface reflector, a plurality of reflecting surfaces are equally distributed on the circumference of the multi-surface reflector, and the rotating mirror motor can drive the multi-surface reflector to continuously rotate; the laser beam emitted by the laser is obliquely directed to the central axis of the multi-surface reflector relative to the normal section of the multi-surface reflector, and the formed reflected beam forms a light spot on an imaging surface above the linear module; when the rotating mirror motor drives the multi-surface reflector to continuously rotate, the reflected light beams are sequentially deflected by the plurality of reflecting surfaces, so that the light spots are scanned on the imaging surface in a reciprocating manner to generate curved scanning lines; an image sensor is arranged above the imaging surface and used for converting the bent scanning lines into a digital pixel map so as to determine the row and column positions of the projection pixels in the bent scanning lines in the rectangular imaging area.

Preferably, the polygon mirror has three reflecting surfaces equally distributed on the circumference thereof.

Preferably, the scanning controller is respectively connected with the linear module, the rotating mirror motor, the laser and the image sensor.

Preferably, the scanning controller is internally provided with a first decoder module, a second decoder module, a row scanning control module, a column scanning control module, a row and column correction module and a laser control module, the rotating mirror motor is connected with the first decoder module, the first decoder module is connected with the row scanning control module, the linear module is connected with the second decoder module, the second decoder module is connected with the column scanning control module, the row scanning control module and the column scanning control module are connected with the row and column correction module, the row and column correction module is connected with the laser control module, and the laser control module is connected with the laser.

A high-efficiency rotary scanning plane imaging method is characterized in that a linear module drives a multi-surface reflector rotary scanning device formed by combining a rigid support, a rotating mirror motor, a laser and a multi-surface reflector to move from a scanning starting line to a scanning ending line; during the movement of the linear module, the curved scanning lines projected by the multi-surface reflector are arranged on the imaging surface line by line along the movement direction of the linear module to form a scanning area; when the linear module continues to move and reaches the scanning termination line, the scanning area is expanded forwards along the movement of the linear module until the rectangular imaging area of the imaging surface is completely covered; in the moving process of the linear module, when the instantaneous imaging pixels in the bent scanning line are positioned in the rectangular imaging area, the scanning controller outputs the pixel gray value of the corresponding position of the current scanning plane image as the brightness control signal of the laser, so that the brightness of each imaging pixel in the rectangular imaging area is consistent with that of the plane image.

A rotary encoder is arranged in a rotary mirror motor, the rotary mirror motor drives a multi-surface reflecting mirror to rotate for 1 circle, and the rotary encoder outputs m incremental pulses and 1 synchronous pulse to a scanning controller; the scan controller decodes the incremental pulse signal and the synchronization pulse of the rotary encoder: adding 1 to the value of each incremental pulse counting register, returning to zero when the value of the counting register is increased to m, recounting, and setting the counting register as an initial value when a synchronous pulse is received; the multi-surface reflector is provided with n reflecting surfaces, the scanning controller generates line synchronizing signals from No. 1 to No. n reflecting surfaces when the values of the counting register are respectively {0, m/n, 2m/n … (n-1) × m/n }, and the scanning controller adjusts the initial values of the counting register between 1 to m/n so that the line synchronizing signals coincide with the initial scanning angles of all the reflecting surfaces; enabling the scanning line to comprise k pixels, and enabling the scanning controller to divide the system clock number of the line synchronization signal period at equal intervals according to the parameters of the reflection light path to obtain a clock interval table from No. 1 to No. k pixels; the scanning controller inquires the position of a system clock counting value in a clock interval table in real time in each line synchronous signal period to determine the pixel number of a projection pixel in a scanning line, and calculates the line position of the scanning line on an imaging surface in real time according to a linear module position signal to determine the column number of the projection pixel in planar image data; and the scanning controller outputs the gray value of the corresponding pixel in the projection plane image data of this time as a laser brightness control signal according to the obtained pixel number and the column number.

A laser beam emitted by a laser device is emitted to a multi-face mirror at an included angle α relative to the normal section of the multi-face mirror, when a straight line module is static, a reflected beam generates central symmetrical curved scanning lines on an imaging surface, and rotary mirror imaging calibration is needed to compensate imaging distortion generated by the curved scanning lines.

When the rotating mirror is used for continuous line-by-line scanning, the total line number of an imaging surface is q, a scanning controller sends a motion signal to a linear module, and the linear module is controlled to drive the rotating mirror and a curved scanning line to stably move from the 1 st line of the imaging surface to the q lines; during the movement of the linear module, the scanning controller calculates the line position of the curved scanning line in real time according to the position of the linear module and the line spacing, comprehensively obtains the line and column position of the real-time projection pixel in the curved scanning line according to the system clock count value of the line synchronization signal period, and further queries a line and column deviation table established in a rotating mirror imaging calibration link to obtain the line and column deviation value of the real-time projection pixel and the imaging pixel position; the scanning controller compensates the searched row and column deviation value to a real-time projection pixel position to obtain a row and column position of an actual imaging pixel position in the current projection plane image data, and outputs a gray value of a pixel at the row and column position as a laser brightness control signal; the process that the pixel gray value is output as the laser brightness control signal is continuously carried out in the process that the linear module moves to q lines until all pixels of the projection plane image data are output according to the moving sequence of the scanning light spots on the imaging surface, so that the plane image is reconstructed on the imaging surface through the line-by-line scanning motion of the single-point imaging light spots.

When the reflecting surface of the rotating mirror deflects and reflects an incident beam, the reflected beam and the incident beam are distributed on two sides of the normal section of the rotating mirror at the reflecting point, and the reflected beam is within the range of the deflection angle of the reflecting surface and has no superposition interference with the incident beam; when the width of a light spot is not counted, the maximum optical scanning angle of the reflecting surface of the rotating mirror can reach 2 times of the circumferential dividing angle of the reflecting surface, correspondingly, the maximum duty ratio of a row synchronous signal of the reflecting surface of the rotating mirror can reach 100 percent, namely, at any time during the line-by-line scanning of the rotating mirror, light beams output by a laser are all used for reconstructing a plane image to be projected on an imaging surface, and the real-time light beam brightness of the laser corresponds to the pixel gray value of the plane image to be projected one by one; the laser of the present invention is not forced to turn off because the reflected beam cannot reach the imaging surface.

When the linear module drives the rotating mirror to continuously scan line by line, the curved scanning lines are arranged line by line and cover a rectangular imaging area of an imaging surface, when instantaneous imaging pixels of the curved scanning lines enter the rectangular imaging area, a scanning controller outputs gray values of corresponding pixels in the projection plane image data of this time as laser brightness control signals according to the row and column positions of the instantaneous imaging pixels in the rectangular imaging area, so that the brightness of the instantaneous imaging pixels in the rectangular imaging area is always consistent with the gray values of the plane image data, and a scanned image with the brightness distribution consistent with the plane image data is reconstructed in the imaging area;

according to the high-efficiency rotary scanning plane imaging method, a bent scanning line of the rotary mirror on an imaging surface is not required to be corrected into a straight line by adopting a precise optical element, and the direction of the scanning line in a rectangular imaging area is not required to be accurately adjusted, so that the direction of the scanning line is overlapped with the row direction of the rectangular imaging area; the invention has simple light path, and the installation deviation of the laser and the imaging surface relative to the rotating mirror can be compensated through the imaging calibration link of the rotating mirror; the laser beam emitted by the laser is reflected by the rotating mirror for 1 time and then is directly imaged, so that the energy loss of the laser beam is small and the efficiency is high; the laser has short passive closing time and high utilization rate in the continuous line-by-line scanning process, has reasonable scheme, and can be popularized and applied in various laser scanning photocuring three-dimensional printers.

Drawings

FIG. 1 is a schematic diagram of the overall structure of an embodiment of the present invention;

FIG. 2 is a control signal connection diagram according to an embodiment of the present invention;

FIG. 3 is a schematic view of a progressive scan planar imaging in accordance with an embodiment of the present invention;

FIG. 4 is a logic diagram of laser brightness control according to an embodiment of the present invention;

description of reference numerals: the device comprises a linear module 1, a rigid support 2, a rotating mirror motor 3, a laser 4, a laser beam 41, a reflected beam 42, a multi-surface reflector 5, a first reflecting surface 51, a second reflecting surface 52, a third reflecting surface 53, an imaging surface 6, a light spot 61, a curved scanning line 62, a rectangular imaging area 63, an image sensor 7, a scanning controller 100, a first decoder module 101, a second decoder module 102, a row scanning control module 103, a column scanning control module 104, a row and column correction module 105 and a laser control module 106.

Detailed Description

The invention will be further described with reference to the accompanying drawings in which: