SYSTEM AND METHOD FOR EXPOSING A MATERIAL WITH AN IMAGE - Patent application

Abstract

1. A system for exposing a material with an image, the system comprising: an exposure table (12); and an electronic light projector (13) arranged above the exposure table (12), the electronic light projector (13) adapted to project an image onto a material placed on the exposure table (12), the electronic light projector and the exposure table configured to be moved relative to each other, the electronic light projector (13) connected to a projector control unit configured to provide a series of images to be exposed represented by image data and to superimpose still image patterns on edge areas of the images to be exposed to result in a series of combined images, the electronic light projector (13) configured to sequentially expose the combined images onto the material.

Description

[Technical field]

[0001] The present invention relates to a process for eliminating undesirable discontinuous effects in adjacent exposure stripes when using devices for exposing photopolymerizable materials (and other materials) for layer-by-layer material solidification to build 3D objects, or for 2D direct write lithography where only one layer is polymerized or exposed. Typical uses would be in 2D direct lithography machines used for PCB, touch panel, solar cell, chemical milling and other manufacturing related lithography, as well as in 3D printers, rapid prototyping machines, rapid manufacturing machines and similar layer-by-layer build process equipment. [Background technology]

[0002] (background) When two adjacent exposure stripes are placed nearby, the polymerized material depends on the positioning of the exposure stripes and the power of each stripe. If the positioning of the exposure stripes is well aligned in the x and y directions with respect to each other (i.e. on the same grid as the image pixels) and the power of the exposure stripes is identical, the result will be optimal. Then, adjacent exposure stripes can be placed near each other ("back to back") or with an overlap area that matches the image pixel grid. If an overlap area is applied, the image data in the overlap area must be removed for one of the image data sets to avoid overexposure.

[0003] However, if the power distribution for the image has some variation orthogonal to the image stripe length, or if the image positioning for each exposure stripe is not on a pixel grid, the polymerized material will have undesirable characteristics such as discontinuous or unexposed areas.

[0004] WO2016 / 124634 (Patent Document 1) describes a method for exposing a photopolymerizable material for layer-by-layer material solidification to build a 3D object. The exposure is carried out by dividing the image to be exposed into multiple partial images with an inter-distance of at least 1 pixel, and sequentially exposing the partial images onto the photopolymerizable material using a light projector.

[0005] EP3040778 describes a method for providing a uniform brightness on an image area from a light projector. This document does not solve the problem of reducing the influence on the exposure result at the edge of adjacent exposure stripes, which influence on the exposure result is caused by differences in the image area and / or the brightness uniformity difference for two adjacent exposure stripes. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2016 / 124634 [Patent Document 2] European Patent No. 3040778 Summary of the Invention [Means for solving the problem]

[0007] (Summary of the invention) It is an object of the present invention to provide a system and method for layer-by-layer exposure of photosensitive or photopolymerizable materials to build 3D objects, or for 2D direct-write lithography, which reduces or eliminates the undesirable effects of the prior art techniques described above.

[0008] Therefore, an object of the present invention is to provide a system and method capable of reducing the effects on exposure results at the edges of adjacent exposure stripes caused by differences in image portions and / or differences in brightness uniformity for two adjacent exposure stripes.

[0009] The systems and methods of the present invention will relax the requirements for brightness uniformity in the exposed image and also relax the tolerances on the mechanisms that control the image position within the machine. Because both brightness uniformity and image positioning mechanisms require expensive mechanical parts, it is easier to provide a cost-effective machine when the tolerances on such parameters are relaxed.

[0010] The object of the invention is achieved with the aid of the features of the claims.

[0011] In one embodiment, a system for exposing a material with an image comprises an exposure table and an electronic light projector arranged above the exposure table, the electronic light projector adapted to project an image towards the material arranged on the exposure table, the electronic light projector and the exposure table configured to be moved relative to each other, the electronic light projector connected to a projector control unit, the projector control unit configured to provide a sequence of images to be exposed, the images being represented by image data, and to superimpose a static image pattern onto edge areas of the images to be exposed, resulting in a sequence of combined images.

[0012] The projector control unit may also be configured to control the superimposition of a still image pattern onto the image to be exposed.

[0013] An electronic light projector is configured to sequentially expose the combined images onto a material.

[0014] This system provides a resulting exposure at the material that provides good uniformity in the overlap areas between adjacent images.

[0015] In one embodiment, the image to be exposed is in the form of CAD (Computer Aided Design) image data, for example stored in a CAD data file, and a still image pattern is superimposed on the data pattern provided by the image data file on each side of the image area.

[0016] The material to be exposed by the electronic light projector is for example a photosensitive or photopolymerizable material. In the latter case, the system can be used for 3D printing as previously described.

[0017] In one embodiment, the electronic light projector is connected to a motor controller that provides a synchronization signal to the electronic light projector to control the movement of the electronic light projector relative to the exposure table, which allows the projector to set the next image in the image sequence.

[0018] In one embodiment, the superimposed pattern is fixed while the image data is presented sequentially. This means that the image projected onto the material to be exposed varies over the entire exposure area to form a complete picture / object. However, the function of the superimposed pattern is to smooth the transition between adjacent stripes and can be fixed, i.e. the image data of the superimposed pattern is the same for each image in the sequence.

[0019] In one embodiment, the overlaid pattern on one side of an exposure stripe is complementary to the other side of an adjacent exposure stripe.

[0020] The overlaid pattern may have a width between the full projected image width and one projected image pixel. In most embodiments, the width is narrower than the full projected image. The length of the overlaid pattern may correspond, for example, to the number of rows in one projected image, i.e., it may have the same length as each image in the sequence.

[0021] The superimposed patterns can have different shapes, for example a sawtooth shape or a stepped sawtooth shape or any other suitable shape.

[0022] Corresponding to the above, in one embodiment, a method of exposing a material imagewise comprises: Providing a series of images to be exposed; superimposing a still image pattern onto edge areas of the image to be exposed to result in a series of combined images; sequentially exposing the combined images onto a material using a light projector; Includes. The present invention provides, for example, the following: (Item 1) A system for exposing a material with an image, the system comprising an exposure table (12) and an electronic light projector (13) arranged above the exposure table (12), the electronic light projector (13) adapted to project an image towards a material arranged on the exposure table (12), the electronic light projector and the exposure table configured to be moved relative to each other, the electronic light projector (13) connected to a projector control unit, the projector control unit being configured to: providing a series of images to be exposed represented by image data; superimposing a still image pattern onto edge areas of the image to be exposed to provide a series of combined images; and wherein the electronic light projector (13) is configured to sequentially expose the combined images onto the material. (Item 2) 2. The system of claim 1, wherein the image to be exposed is in the form of CAD (Computer Aided Design) image data (72) with a still image pattern (71), the still image pattern (71) being superimposed on the data pattern given by a CAD file on each side of the image area. (Item 3) 2. The system of claim 1, wherein the material (11) is a photosensitive or photopolymerizable material. (Item 4) 2. The system of claim 1, wherein the electronic light projector (13) is connected to a motor controller, which provides the electronic light projector with a synchronization signal (15) for controlling the movement of the electronic light projector relative to the exposure table to enable the projector to set the next image in an image sequence. (Item 5) 2. The system of claim 1, wherein the superimposed pattern is fixed while the image data is presented sequentially. (Item 6) 2. The system of claim 1, wherein the superimposed pattern on one side of an exposure stripe is complementary to the other side of the adjacent exposure stripe. (Item 7) 2. The system of claim 1, wherein the projector control unit is configured to control the superimposition of the still image pattern onto the image to be exposed. (Item 8) 2. The system of claim 1, wherein the overlaid pattern has a width between the full projected image width and one projected image pixel. (Item 9) Item 2. The system of item 1, wherein the superimposed pattern has a length corresponding to the number of rows in one projected image. (Item 10) Item 2. The system of item 1, wherein the overlaid pattern is in the shape of a sawtooth. (Item 11) Item 11. The system of item 10, wherein the overlaid pattern is in the shape of a stepped sawtooth. (Item 12) 1. A method of exposing a material imagewise, the method comprising the steps of: Providing a series of images to be exposed; superimposing a still image pattern onto edge areas of the image to be exposed to provide a series of combined images; sequentially exposing the combined images onto the material using a light projector; A method comprising: (Item 13) 13. The method according to claim 12, wherein the image to be exposed is in the form of CAD (Computer Aided Design) image data (72) with a still image pattern (71), the still image pattern (71) being superimposed on the data pattern given by a CAD file on each side of the image area. (Item 14) 13. The method according to claim 12, comprising providing an electronic light projector with a synchronization signal (15) for controlling movement of the electronic light projector relative to the exposure table, thereby enabling the projector to set the next image in an image sequence. (Item 15) 13. The method according to claim 12, further comprising controlling the sequence of images to be exposed. [Brief description of the drawings]

[0023] (Detailed Description) The invention will now be described in more detail with reference to the accompanying drawings.

[0024] [Figure 1] FIG. 1 illustrates a system for solidification of a layer of photopolymerizable material in a 3D printer / rapid manufacturing machine or a 2D lithography machine.

[0025] [Diagram 2] FIG. 2 illustrates the exposure process performed by a system according to the present invention.

[0026] [Diagram 3] FIG. 3 illustrates an ideal situation during exposure where the brightness uniformity for the exposed image from the light projector is ideal and the positioning of adjacent exposure stripes is ideal.

[0027] [Figure 4] FIG. 4 illustrates a non-ideal situation during exposure where the brightness uniformity causes a discontinuity in the output between adjacent exposure stripes.

[0028] [Diagram 5] FIG. 5 illustrates the resulting power distribution after exposure of the overlap area using one embodiment of the system.

[0029] [Figure 6] FIG. 6 illustrates the resulting image distribution after exposure of an overlap area with offsets in x and y using one embodiment of the system.

[0030] [Figure 7] FIG. 7 illustrates an example of a CAD image and an overlaid pattern exposed onto a material by a light projector.

[0031] [Figure 8] FIG. 8 illustrates an example of superimposed patterns on both sides of an image to be exposed.

[0032] [Figure 9] FIG. 9 illustrates another example of superimposed patterns on both sides of an image to be exposed.

[0033] [Figure 10] FIG. 10 illustrates an example of how a CAD image is exposed onto a photosensitive material using two exposure stripes from an image projector.

[0034] [Figure 11] FIG. 11 illustrates an example of exposure of two adjacent images resulting in unexposed areas on the edges between the exposure stripes.

[0035] [Figure 12]FIG. 12 illustrates another example of exposure of two adjacent images resulting in unexposed areas on the edges between the exposure stripes. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] In FIG. 1 a system 10 for layer-by-layer exposure of a light-sensitive or photopolymerizable material 11 for building up a 3D object or for 2D direct-write lithography is depicted.

[0037] The system comprises an exposure table 12 and an electronic light projector 13 arranged above the exposure table 12. The electronic light projector 13 is capable of projecting light 14 towards the exposure table 12 and thus onto any medium 11 arranged on the exposure table 12, thereby projecting an image onto the medium. The medium 11 is for example a light-sensitive or photopolymerizable material. The electronic light projector 13 moves relative to the material 11 to be exposed while a synchronization signal 15 is provided by a motor controller that enables the projector to set the next image in the image sequence.

[0038] An electronic light projector comprises a space modulator (e.g. DLP / LCD / LCOS or similar light / output projector) which serves as a curing light source / output source for the solidification of a layer of photopolymerizable material in a 3D printer / rapid manufacturing machine or a 2D lithography machine (direct write exposure machine). As illustrated in Fig. 2, the process is carried out such that the projected image moves relative to the material to be exposed, thereby producing adjacent exposure stripes of data. The exposure stripes 21, 22 slightly overlap, thus providing an overlap area 23.

[0039] When multiple exposure stripes are required, the power distribution (brightness uniformity) for the image is an important parameter for projectors used in motion systems. Figure 3 illustrates the ideal situation where the power and image positioning are correctly aligned, thus providing a uniform combined exposed image 30.

[0040] If the brightness uniformity is not within a certain tolerance, and depending on the sensitivity of the material being exposed, this will be very noticeable when comparing adjacent exposed stripes, either when one projector or when multiple projectors are used. This will provide a discontinuous step 41 in the polymerization result of the exposed material on the edges between adjacent stripes. Figure 4 illustrates this situation.

[0041] If the tolerance of the mechanical alignment of the projector(s) to the exposed material is not a fraction of the projected pixel size, there will also be image offset in both the x and y directions between the exposure stripes. This will cause unexposed or overexposed areas on the edges between the exposure stripes when adjacent exposure stripes overlap. Examples of such situations are illustrated in Figures 11 and 12.

[0042] When the exposure in motion in the motion system covers a larger area than the image by moving in both y and x directions on the machine, the process blurs the power difference, and the image offset difference between the exposure stripes is blurred throughout the shared area between the exposure stripes. This may be called the edge blending area. This blurring will ensure that any difference in power or pixel edges between the exposure stripes has a continuous nature rather than a discontinuous nature. Figures 5 and 6 illustrate this situation. The example in the figure shows two exposure stripes 51, 52, where the projected image of the second stripe 52 is offset in both x and y directions with respect to the projected image of the first stripe 51. Thus, the image in the overlap area 53 is an edge blend of the two image stripes, and the power distribution in the overlap area is blurred. In Figure 5, power curves 54, 55 representing the two exposure stripes 51, 52 are illustrated. Thus, the resulting overlap area power curve 53 is a smooth and continuous curve. This continuous nature will improve the quality of the exposure result. The process can also be used when multiple light projectors are used in the same system for one axis only (the y axis), or for two axes (the x and y axes) to produce adjacent exposure stripes.

[0043] FIG. 7 illustrates an example of an image exposed on a material by an electronic light projector. The image may be, for example, in the form of CAD (Computer Aided Design) image data 72 with a static image pattern 71, which is superimposed on the data pattern given by the CAD file on each side of the image area. The width of the static image pattern 71 may be varied depending on the requirements of the concrete application. In the extreme case, the width of the pattern may be as wide as the image or exposure stripe, while the minimum width is one image pixel. Typically, the pattern width will be the same as the typical tolerances on tooling for use in such applications, i.e. 20-200 μm.

[0044] As the CAD file data pattern scrolls across the projector image synchronized with the relative movement of the table on which the material to be exposed is placed, the superimposed pattern is logically "ANDed" on a pixel-by-pixel basis with the data pattern provided by the CAD file.

[0045] Both sides 71 of the image area constitute intentional overlap areas between adjacent exposure stripes. The portions of the images contained within the overlap areas contain the image patterns that are superimposed. The data patterns provided by the CAD file are identical on adjacent exposure stripes within the overlap area, so that the right side of a first exposure stripe within the overlap area is identical to the left side of a second exposure stripe within the overlap area. The overlapping CAD data between adjacent image stripes is also illustrated in FIG. 10.

[0046] Figures 8 and 9 show two examples of possible shapes of the overlapping patterns. The figures illustrate both the right side of the first exposure stripe and the left side of the second exposure stripe. As shown in Figures 8 and 9, the overlapping patterns on each side have complementary shapes. This ensures a uniform power distribution in the overlap area.

[0047] To obtain the best exposure results in the areas between the exposure stripes, the overlaid pattern can be customized depending on the nature of the polymerized material being exposed. As shown in Figures 7-9, the pattern can be repeated over the entire image stripe length.

[0048] The overlaid patterns in the image overlap area between two adjacent exposed stripes can be varied in size orthogonal to the stripe length (the width of the overlap area) depending on the extent of edge blending desired.

[0049] The overlapped pattern length along the direction of the exposure stripe is limited by the number of rows in one image (one DMD height). In the example of Figure 7, the number is 1080 (HD) or 1600 (WQXGA), but other image resolutions such as 2160 (4k) can also be used.

[0050] During exposure, the superimposed pattern may be fixed while the data pattern given by the CAD file is scrolled / sequentially exposed according to the relative movement between the exposed material and the projector.

[0051] The overlaid patterns may be pre-programmed or overlaid by a projector control unit that may be connected to or included in the projector. In one embodiment, the control system may be programmed in an external PC that controls the projector.

[0052] The results exposed by using a system according to the invention provide a continuous power shift between adjacent exposure stripes and a continuous position shift between adjacent exposure stripes.

Claims

1. A system for exposing a material with an image, the system comprising an exposure table (12) and an electronic light projector (13) arranged above the exposure table (12), the electronic light projector (13) adapted to project an image towards a material arranged on the exposure table (12), the electronic light projector and the exposure table being configured to be moved relative to each other during exposure, the electronic light projector (13) being connected to a projector control unit, the projector control unit being configured to: providing a series of images to be exposed represented by image data; superimposing a still image pattern on an edge area of ​​the image to be exposed to produce a series of combined images, the still image pattern having a width narrower than the image to be exposed; and the electronic light projector (13) is configured to sequentially expose the combined images onto the material; The superimposed still image pattern is orthogonal to a stripe length based on an edge blending region, the edge blending region being generated by the electro-optic projector moving in both x and y directions within a motion system to blend the edge areas of the image to be exposed.

2. 2. The system of claim 1, wherein the image to be exposed is in the form of CAD (Computer Aided Design) image data (72) with a still image pattern (71) superimposed on the edge areas of the image to be exposed given by a CAD file on each side of the image to be exposed.

3. The system of claim 1 , wherein the material (11) is a photosensitive or photopolymerizable material.

4. 2. The system of claim 1, wherein the electronic light projector (13) is connected to a motor controller, the motor controller providing the electronic light projector with a synchronization signal (15) for controlling the movement of the electronic light projector relative to the exposure table to enable the projector to set the next image in an image sequence.

5. The system of claim 1 , wherein the superimposed pattern is fixed while the image data is presented sequentially.

6. 2. The system of claim 1, wherein the overlaid pattern on one edge area of ​​one of the images to be exposed is complementary to another edge area of ​​another image to be exposed adjacent to the one of the images to be exposed.

7. The system of claim 1 , wherein the projector control unit is configured to control the superimposition of the still image pattern onto the image to be exposed.

8. The system of claim 1 , wherein the overlaid pattern has a width between the full projected image width and one projected image pixel.

9. The system of claim 1 , wherein the superimposed pattern has a length corresponding to a number of rows in a single projected image.

10. The system of claim 1 , wherein the overlaid pattern is in the shape of a sawtooth.

11. The system of claim 10 , wherein the overlaid pattern is in the shape of a stepped sawtooth.

12. 1. A method of exposing a material imagewise, the method comprising the steps of: Providing a series of images to be exposed; superimposing a still image pattern on an edge area of ​​the image to be exposed to result in a series of combined images, the still image pattern having a width narrower than the image to be exposed; sequentially exposing the combined images onto the material using a light projector; wherein the light projector and the material are moved relative to one another during exposure, and the superimposed still image pattern is orthogonal to a stripe length based on an edge blending region, the edge blending region being created by the light projector moving in both x and y directions within a motion system to blend the edge areas of the image to be exposed.

13. 13. The method of claim 12, wherein the image to be exposed is in the form of CAD (Computer Aided Design) image data (72) with a still image pattern (71) superimposed on the edge areas of the image to be exposed given by a CAD file on each side of the image to be exposed.

14. 13. The method of claim 12, comprising providing a synchronization signal (15) to the light projector for controlling movement of the light projector relative to the material, thereby enabling the projector to set the next image in an image sequence.

15. 13. The method of claim 12, further comprising controlling the sequence of images to be exposed.

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