WO2020125570A1

WO2020125570A1 - Photocuring 3d printing device and image exposure system thereof

Info

Publication number: WO2020125570A1
Application number: PCT/CN2019/125538
Authority: WO
Inventors: 侯锋
Original assignee: 上海普利生机电科技有限公司
Priority date: 2018-12-17
Filing date: 2019-12-16
Publication date: 2020-06-25
Also published as: CN111319257A

Abstract

An image exposure system for a 3D printing device, which uses a silicon-based liquid crystal panel (203) as an array image source. The silicon-based liquid crystal panel (203) comprises a lens electrode array (302), a common electrode (304), a liquid crystal (305) located between the lens electrode array (302) and the common electrode (304), a first alignment film (303) located between the lens electrode array (302) and the liquid crystal (305), and a second alignment film (306) located between the liquid crystal (305) and the common electrode (304). The first alignment film (303) protrudes at each lens electrode (E) corresponding to the lens electrode array (302) to form focusing lenses. Each focusing lens is capable of converging the light irradiated to the corresponding lens electrode (E) so that the size (s) of a micro spot reflected by the lens electrode (E) is less than the size of a pixel corresponding to the lens electrode (E). The silicon-based liquid crystal panel (203) is used for adjusting the state of the liquid crystal (305) according to a control signal so as to change the polarization direction of each light reflected by the lens electrode array (302).

Description

Photocuring 3D printing equipment and its image exposure system

Technical field

The invention relates to a photo-curing 3D printing device, in particular to an image exposure system of the photo-curing 3D printing device.

Background technique

3D printing technology is based on the computer three-dimensional design model, through the software layered discrete and numerical control forming system, using laser beams, hot melt nozzles and other methods to deposit metal powder, ceramic powder, plastic, cell tissue and other special materials layer by layer Bonding, and finally superimposed to form a physical product. Unlike the traditional manufacturing industry, which molds and cuts raw materials by mechanical processing methods such as molds, turning and milling to finally produce finished products, 3D printing turns three-dimensional entities into several two-dimensional planes. By processing materials and stacking them layer by layer, production is greatly improved. Reduced manufacturing complexity. This digital manufacturing mode does not require complex processes, huge machine tools, or a lot of manpower. It can generate parts of any shape directly from computer graphics data, enabling production to extend to a wider range of production populations.

At present, the molding method of 3D printing technology is still evolving, and the materials used are also diverse. Among various molding methods, the light curing method is a relatively mature method. The light curing method is based on the principle that the photosensitive resin is cured after being irradiated with ultraviolet light, and the material is cumulatively formed, which has the characteristics of high molding accuracy, good surface finish, and high material utilization rate.

FIG. 1 shows the basic structure of a photocurable 3D printing apparatus. This 3D printing apparatus 100 includes a material tank 110 for accommodating photosensitive resin, an image exposure system 120 for curing the photosensitive resin, and a lifting table 130 for connecting molding workpieces. The image exposure system 120 is located above the material tank 110, and can irradiate the beam image to cure a layer of photosensitive resin on the liquid surface of the material tank 110. Each time the image exposure system 120 irradiates the beam image to cause a layer of photosensitive resin to cure, the lifting table 130 will drive the layer of cured photosensitive resin slightly down, and spread the photosensitive resin evenly on the top surface of the cured workpiece through the scraper 131. Wait for the next irradiation. Such a cycle will result in a layer-by-layer cumulatively shaped three-dimensional workpiece.

The image exposure system 120 can use laser forming technology, digital light processing (Digital Light Processing (DLP), liquid crystal on silicon (Liquid Crystal on Silicon, LCOS) projection technology.

Laser forming technology is to use laser scanning equipment for point-by-point scanning. However, due to the characteristics of photosensitive resin, the laser power should not be too large, otherwise it will damage the resin. Therefore, the laser moving speed is limited to a few meters to more than ten meters per second, resulting in too slow molding speed.

LCOS is a matrix liquid crystal display device with very small pixel size based on reflection mode. This matrix is fabricated on silicon chips using CMOS technology. The circuit of the matrix provides a voltage between the electrode of each pixel and the common transparent electrode, which is separated by a thin layer of liquid crystal. The electrode of the pixel is also a reflecting mirror (hereinafter referred to as a mirror electrode), and the electrodes of all pixels together form a reflecting mirror surface. An electronic circuit that controls image formation is fabricated on a silicon chip, and the polarization direction of incident polarized light of each pixel is changed by controlling the state of liquid crystal molecules. The light reflected by the mirror electrode is separated from the incident light by an optical method to be amplified by the projection objective and imaged onto the object. Eventually, the entire reflection projects the desired beam image. When LCOS is used in 3D printing, the limited resolution restricts its development. For example, the highest resolution commonly used in current LCOS is usually 1920*1080. However, this resolution can only produce objects with an area of 192*108mm with the commonly used precision of 0.1mm in 3D printing, which obviously limits its application.

Summary of the invention

The technical problem to be solved by the present invention is to provide a photo-curing 3D printing device and its image exposure system.

The technical solution adopted by the present invention to solve the above technical problems is to propose an image exposure system for a 3D printing device, which includes: a silicon-based liquid crystal panel, including a mirror electrode array, a common electrode, the mirror electrode array and the common electrode Between the liquid crystal, the first alignment film between the mirror electrode array and the liquid crystal, and the second alignment film between the liquid crystal and the common electrode, the first alignment film corresponds to the Each mirror electrode of the mirror electrode array is convex to form a focusing lens, and each focusing lens can condense the light irradiated to the corresponding mirror electrode, so that the reflected micro spot size of the mirror electrode is smaller than that corresponding to the mirror electrode Pixel size, wherein the silicon-based liquid crystal panel is used to adjust the state of the liquid crystal according to a control signal, thereby changing the polarization direction of each light reflected by the mirror electrode array; the light source generates an illumination to the silicon-based Light on the liquid crystal panel; polarized beam splitter, used to filter the light generated by the light source into polarized light to illuminate the silicon-based liquid crystal panel, and filter out the predetermined polarization direction from the light reflected by the mirror electrode array Projection light, set in the exit direction of the polarizing beam splitter, so that the micro-spot array composed of micro-spots reflected by each mirror electrode is projected onto the surface of the photosensitive material; the micro-displacement driving mechanism is connected to the silicon-based liquid crystal A panel capable of driving the liquid crystal on silicon panel to move in a first direction and a second direction perpendicular to each other to fine-tune the position of the micro-spot array projected onto the surface of the photosensitive material; and a controller to instruct the light source to perform multiple In the second exposure, the micro-displacement drive mechanism is commanded to move during each exposure to project the micro-spot array of each exposure to different positions on the surface of the photosensitive material.

In an embodiment of the present invention, the images formed by the micro-spot array of each exposure on the surface of the photosensitive material do not overlap each other.

In an embodiment of the invention, the image formed by the micro-spot array of each exposure covers the surface of the photosensitive material.

In an embodiment of the invention, the micro-spot array of each exposure contains different image information.

In an embodiment of the present invention, it is assumed that the focal length of each focusing lens is f, the pixel size corresponding to each focusing lens is p, the half-angle of the light incident on each micromirror is β, and the image height of the micro-spot is a , The maximum half-angle of the outgoing light is W, then satisfy:

tan(β)=(a/2)/(f/2);

tan(w)=((a+p)/2)/(f/2);

Fno = 1/(2tan(w)).

The present invention also provides an image exposure system for a 3D printing device, including: a silicon-based liquid crystal panel, including a mirror electrode array, a common electrode, liquid crystal between the mirror electrode array and the common electrode, and the mirror electrode A first alignment film between the array and the liquid crystal and a second alignment film between the liquid crystal and the common electrode, each mirror electrode of the mirror electrode array is a concave mirror, which can be converged and irradiated onto it Light, the size of the reflected micro-spot is smaller than the pixel size corresponding to the mirror electrode, wherein the liquid crystal on silicon panel is used to adjust the state of the liquid crystal according to the control signal, thereby changing each reflection by the mirror electrode array The polarization direction of the light; the light source generates a light shining on the silicon-based liquid crystal panel; the polarized beam splitter is used to filter the light generated by the light source into polarized light to illuminate the silicon-based liquid crystal panel, And filter out the light of a predetermined polarization direction from the light reflected by the mirror electrode array; the projection lens is provided in the exit direction of the polarizing beam splitter to make the micro-spot array composed of the micro-spots reflected by each mirror electrode Projected onto the surface of the photosensitive material; a micro-displacement drive mechanism, connected to the silicon-based liquid crystal panel, can drive the silicon-based liquid crystal panel to move in a first direction and a second direction perpendicular to each other, to fine-tune the projection of the micro-spot array onto the The position of the surface of the photosensitive material; and a controller instructing the light source to perform multiple exposures, and in each exposure instructs the micro-displacement drive mechanism to move to project the micro-spot array of each exposure onto the photosensitive material Different locations on the surface.

In an embodiment of the invention, the size of the micro-spot is less than, equal to or greater than half the size of the pixel corresponding to the mirror electrode.

In an embodiment of the present invention, it is assumed that the focal length of each mirror electrode concave mirror is f, the pixel size corresponding to each mirror electrode is p, the half angle of the light incident on each mirror electrode is β, and the image height of the micro-spot Is a, and the maximum half-angle of the outgoing light is W, then satisfy:

tan(β)=(a/2)/f;

tan(w)=((a+p)/2)/f;

Fno = 1/(2tan(w)).

In an embodiment of the invention, the first alignment film is correspondingly recessed at each mirror electrode concave mirror of the mirror electrode array.

The present invention also provides an image exposure system for a 3D printing device, including: a silicon-based liquid crystal panel, including a mirror electrode array, a common electrode, liquid crystal between the mirror electrode array and the common electrode, and the mirror electrode A first alignment film between the array and the liquid crystal, a second alignment film between the liquid crystal and the common electrode, and a focusing lens array on the incident side of the common electrode, the focusing lens array Each focusing lens corresponds to each mirror electrode of the mirror electrode array, and each focusing lens can condense the light irradiated to the corresponding mirror electrode, so that the reflected micro spot size of the mirror electrode is smaller than that corresponding to the mirror electrode Pixel size, where the silicon-on-silicon liquid crystal panel is used to adjust the state of the liquid crystal according to a control signal, thereby changing the polarization direction of light reflected by the mirror electrode array; the light source generates an illumination to the silicon-on-liquid crystal panel Polarized beam splitter, used to filter the light generated by the light source into polarized light to illuminate the silicon-based liquid crystal panel, and filter out the light of a predetermined polarization direction from the light reflected by the mirror electrode array A projection lens, set in the exit direction of the polarized beam splitter, so that the micro-spot array is projected onto the surface of the photosensitive material; a micro-displacement drive mechanism, connected to the silicon-based liquid crystal panel, can drive the silicon-based liquid crystal panel Moving in a first direction and a second direction perpendicular to each other to fine-tune the position of the micro-spot array projected onto the surface of the photosensitive material; and the controller instructs the light source to perform multiple exposures, instructing the The micro-displacement driving mechanism moves to project the micro-spot array of each exposure to different positions on the surface of the photosensitive material.

In an embodiment of the present invention, the images formed by the micro-spot array of each exposure on the surface of the photosensitive material do not completely overlap each other.

In an embodiment of the present invention, it is assumed that the focal length of each focusing lens is f, the pixel size corresponding to each focusing lens is p, the distance between the focusing lens and the corresponding reflective electrode is d, and the light incident on each micromirror If the half angle is β, the image height of the micro-spot is a, and f>d, then satisfy:

a=(f ² *tanβ)/(fd)

Among them, Fno1 or Fno2 with the largest absolute value is Fno.

The present invention also provides an image exposure system for a 3D printing device, including: a silicon-based liquid crystal panel, including a mirror electrode array, a common electrode, liquid crystal between the mirror electrode array and the common electrode, and the mirror electrode A first alignment film between the array and the liquid crystal and a second alignment film between the liquid crystal and the common electrode, the alignment film protruding at each mirror electrode corresponding to the mirror electrode array Forming a focusing lens, each focusing lens can converge the light irradiated to the corresponding mirror electrode, so that the reflected micro spot size of the mirror electrode is smaller than the pixel size corresponding to the mirror electrode, wherein the silicon-based liquid crystal panel is used for Adjust the state of the liquid crystal according to the control signal, thereby changing the polarization direction of the light reflected by the mirror electrode array; the light source generates a light shining on the silicon-based liquid crystal panel; the polarized beam splitter is used to The light filtering generated by the light source illuminates the silicon-based liquid crystal panel with polarized light, and filters out light of a predetermined polarization direction from the light reflected by the mirror electrode array; a projection lens is provided on the polarized beam splitter The exit direction of the lens makes the micro-spot array composed of micro-spots reflected by the mirror electrodes project onto the surface of the photosensitive material; the deflection lens is arranged between the silicon-based liquid crystal panel and the surface of the photosensitive material, the deflection lens can Deflect around at least one rotation axis perpendicular to the optical axis of the projection lens to fine-tune the position of the micro-spot array projected onto the surface of the photosensitive material; and the controller to instruct the light source to perform multiple exposures at each exposure Time to command the deflection lens to move to project the micro-spot array of each exposure to different positions on the surface of the photosensitive material.

The present invention also provides an image exposure system for a 3D printing device, including: a silicon-based liquid crystal panel, including a mirror electrode array, a common electrode, liquid crystal between the mirror electrode array and the common electrode, and the mirror electrode A first alignment film between the array and the liquid crystal and a second alignment film between the liquid crystal and the common electrode, each mirror electrode of the mirror electrode array is a concave mirror, which can be converged and irradiated onto it Light, the size of the reflected micro spot is smaller than the pixel size corresponding to the mirror electrode, wherein the liquid crystal on silicon panel is used to adjust the state of the liquid crystal according to the control signal, thereby changing the light reflected by the mirror electrode array The polarization direction of the light source; the light source generates a light shining on the silicon-based liquid crystal panel; the polarized beam splitter is used to filter the light generated by the light source into polarized light to illuminate the silicon-based liquid crystal panel, and from The light reflected by the mirror electrode array filters out light with a predetermined polarization direction; a projection lens is provided in the exit direction of the polarizing beam splitter, so that the micro-spot array composed of the micro-spots reflected by each mirror electrode is projected onto A surface of photosensitive material; a deflection lens arranged between the liquid crystal on silicon panel and the surface of the photosensitive material, the deflection lens can be deflected around at least one rotation axis perpendicular to the optical axis of the projection lens to fine tune the micro A spot array is projected onto the surface of the photosensitive material; and a controller commands the light source to perform multiple exposures, and commands the deflection lens to move during each exposure to project the micro-spot array of each exposure onto Describe the different positions on the surface of the photosensitive material.

The present invention also provides an image exposure system for a 3D printing device, including: a silicon-based liquid crystal panel, including a mirror electrode array, a common electrode, liquid crystal between the mirror electrode array and the common electrode, and the mirror electrode A first alignment film between the array and the liquid crystal, a second alignment film between the liquid crystal and the common electrode, and a focusing lens array on the incident side of the common electrode, each of the focusing lens array A focusing lens corresponds to each mirror electrode of the mirror electrode array, and each focusing lens can condense the light irradiated to the corresponding mirror electrode, so that the reflected micro spot size of the mirror electrode is smaller than the pixel corresponding to the mirror electrode Size, wherein the liquid crystal on silicon panel is used to adjust the state of the liquid crystal according to the control signal, thereby changing the polarization direction of the light reflected by the mirror electrode array; the light source generates an illumination on the liquid crystal on silicon panel Polarized beam splitter, used to filter the light generated by the light source into polarized light to illuminate the silicon-based liquid crystal panel, and filter out the light of a predetermined polarization direction from the light reflected by the mirror electrode array; A projection lens is provided in the exit direction of the polarized beam splitter, so that the micro-spot array is projected onto the surface of the photosensitive material; a deflection lens is arranged between the silicon-based liquid crystal panel and the surface of the photosensitive material. The deflection lens can be deflected around at least one rotation axis perpendicular to the optical axis of the projection lens to fine-tune the position of the micro-spot array projected onto the surface of the photosensitive material; and the controller commands the light source to perform multiple exposures, at The micro-displacement driving mechanism is commanded to move during each exposure to project the micro-spot array of each exposure to different positions on the surface of the photosensitive material.

The invention also proposes a photo-curing 3D printing device, including the image exposure system as described above.

Compared with the prior art, the present invention adopts the above technical solutions, by providing a concave lens surface or a focusing lens array in a silicon-based liquid crystal panel, combined with multiple exposures and the micro-displacement of the silicon-based liquid crystal, the photosensitive material surface can be filled Exposure spot, and then use different imaging information for each exposure, can double the resolution of imaging, thereby improving the accuracy of printing.

In addition, when the photocurable material is cured, the material will shrink by a certain amount. When a large area photocurable material is simultaneously photocured, a large continuous internal stress will be generated, which will cause the cured object to warp and deform. Double exposure to cure different pixels of the photosensitive material in a time-sharing manner, avoiding the simultaneous curing of large-area photo-curable materials, reducing the influence of the pixels on the surrounding pixels during curing shrinkage, thereby improving the warpage and deformation of the printed body Degree.

Brief description of the drawings

In order to make the above objects, features and advantages of the present invention more obvious and understandable, the following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings, in which:

FIG. 1 shows the basic structure of a photocurable 3D printing apparatus.

FIG. 2 shows an image exposure system of a 3D printing apparatus according to an embodiment of the invention.

FIG. 3A shows a structural diagram of an embodiment of a silicon-based liquid crystal panel of the image exposure system shown in FIG. 2.

3B is a schematic diagram of one pixel of the silicon-based liquid crystal panel shown in FIG. 3A.

FIG. 3C shows an optical path diagram of the silicon-based liquid crystal panel of FIG. 3A.

FIG. 4A shows a structural diagram of another embodiment of the silicon-based liquid crystal panel of the image exposure system shown in FIG. 2.

4B is a schematic diagram of a pixel of the silicon-based liquid crystal panel shown in FIG. 4A.

4C is a schematic view of the structure of the concave mirror of the silicon-based liquid crystal panel shown in FIG. 4A.

FIG. 4D shows an optical path diagram of the silicon-based liquid crystal panel of FIG. 4A.

FIG. 5A shows a structural diagram of still another embodiment of the silicon-based liquid crystal panel of the image exposure system shown in FIG. 2.

FIG. 5B shows an optical path diagram of the silicon-based liquid crystal panel of FIG. 5A.

FIG. 6 shows an image projected directly when the silicon-based liquid crystal panel is not condensed.

FIG. 7 shows an image formed by the image exposure system of an embodiment of the present invention once exposed on the surface of the photosensitive material.

FIG. 8 shows an image formed by exposure of the image exposure system of the embodiment of the present invention four times on the surface of the photosensitive material.

FIG. 9 shows a schematic diagram of image extraction by the image exposure system of the embodiment of the present invention.

FIG. 10 shows an image exposure system of a 3D printing apparatus according to another embodiment of the present invention.

FIG. 11 shows a schematic view of the undeflected optical path of the deflection lens of the image exposure system shown in FIG. 10.

FIG. 12 shows a schematic diagram of the optical path in which the deflection lens of the image exposure system shown in FIG. 10 is deflected.

FIG. 13 shows an image formed by exposing the image exposure system on the surface of the photosensitive material 4 times in another embodiment of the present invention.

Fig. 14 shows the relationship between the energy required for curing the photosensitive resin and the light power.

Preferred embodiments of the invention

Embodiments of the present invention describe a 3D printing device and its image exposure system, which uses a silicon-based liquid crystal panel as an area image source.

FIG. 2 shows an image exposure system of a 3D printing apparatus according to an embodiment of the invention. Referring to FIG. 2, the image exposure system 200 of this embodiment includes a light source 201, a polarizing beam splitter prism 202, a liquid crystal on silicon (LCOS) panel 203, a micro-displacement mechanism 204, a projection lens 205, and a controller (not shown) . For simplicity, devices not related to the present invention are not shown.

The light source 201 is used to generate a light beam to be irradiated onto the LCOS panel 203. The wavelength of the light emitted by the light source 201 depends on the cured photosensitive material. For example, when UV resin is selected as the photosensitive material, the light beam may be violet to ultraviolet light, and its wavelength is below 430 nm, such as 355-410 nm.

In this embodiment, a polarizing beam splitter prism 202 is provided between the light source 201 and the LCOS panel 203. The light emitted by the light source 201 irradiates the polarized beam splitter prism 202, and the polarized beam splitter prism 202 reflects the S-polarized light in the light to the LCOS panel 203, the P-polarized light directly passes through the polarized beam splitter prism, and finally the light passes through the LCOS panel After the reflection in 203, the light whose polarization direction has not been changed is reflected back to the light source, and the light whose polarization direction has been changed is irradiated onto the photosensitive material surface 220 through the polarizing beam splitter prism 202 and the projection lens 205. Here, the polarization beam splitter prism 202 can split the incident light into two perpendicular linearly polarized lights. Among them, the P-polarized light passes completely, while the S-polarized light is reflected at an angle of 90 degrees, and the exit direction is at an angle of 90 degrees to the P light. S-polarized light is incident on the LCOS panel 203 as incident light. The S polarized light entering the LCOS panel 203 will be twisted by some liquid crystal molecules by a certain angle, and the twist angle is controlled by the voltage applied to the liquid crystal panel. These light rays will be reflected back to the polarization beam splitter prism 202 by the LCOS panel 203. The P-polarized light in the reflected light directly exits from the exit side of the polarized beam splitter prism 202, and the S-polarized light is reflected back to the light source by the polarized beam splitter prism 202. Therefore, by individually controlling the arrangement direction of the liquid crystal molecules of each liquid crystal cell, the brightness and image of the reflected light of the LCOS panel 203 can be controlled. Although a polarizing beam splitter prism is used here, it can be understood that other polarizing beam splitters such as reflective polarizers can also be used in the embodiments of the present invention.

The LCOS panel 203 is used as a spatial light modulator in the present invention. FIG. 3A shows a structural diagram of an embodiment of the LCOS panel of the image exposure system shown in FIG. 2, and FIG. 3c shows an optical path diagram of the LCOS panel of FIG. 3A. 3A and 3B, the LCOS panel 203 may include a circuit substrate 301, a mirror electrode array 302, a first alignment film 303, a common electrode 304, a liquid crystal 305, a second alignment film 306, and a light-transmitting plate 307. A CMOS circuit may be provided on the circuit substrate 301, which includes a plurality of CMOS switches for controlling the operation of the LCOS panel 203 according to the control signal. The mirror electrode array 302 includes many mirror electrodes E, and each mirror electrode E corresponds to one pixel of the LCOS panel 203. The first alignment film 303 covers the mirror electrode array 302, which is a thin film with straight strip-shaped grooves, and serves to guide the arrangement direction of the liquid crystal molecules. The second alignment film 306 covers the common electrode 304 and is opposite to the first alignment film 303. It is a thin film with straight grooves, and serves to guide the arrangement direction of liquid crystal molecules. The common electrode 304 is arranged opposite to the mirror electrode array 302, and they are separated by a certain distance. The common electrode 304 is a transparent electrode, and its material is, for example, ITO (Indium Tin Oxide). The liquid crystal 305 is located between the mirror electrode array 302 and the common electrode 304, and is arranged along the groove direction of the first alignment film 303 and the second alignment film 306. When a voltage is applied to the mirror electrode array 302 and the common electrode 304, the molecules in the liquid crystal 305 will twist a certain angle between them, thereby changing the polarization direction of light passing therethrough. Each mirror electrode E in the mirror electrode array 302 may be applied with a different voltage, so that the twist angle of the liquid crystal molecules above each mirror electrode E is different. The mirror electrode E itself is still a mirror surface, which can reflect light penetrating through the liquid crystal 305 and return it to its original path. Therefore, the liquid crystal on silicon panel 203 can adjust the state of the liquid crystal 305 according to the control signal, thereby changing the polarization direction of the light of the micro-spot M reflected by each mirror electrode E. The micro-spots reflected by the mirror electrodes E constitute an array of micro-spots with adjustable images. In this embodiment, there is a focusing lens 303a under the first alignment film 303, so that the light beam irradiated onto the mirror electrode E can be condensed so that the reflected micro-spot size s is smaller than the pixel size corresponding to the mirror electrode E. In some embodiments, the pixel size corresponding to the mirror electrode E may be the size of the mirror electrode E itself.

In the embodiment of the present invention, the first alignment film 303 is convex at each mirror electrode E corresponding to the mirror electrode array to form a focusing lens. Referring to FIG. 3B, the first alignment film 303 is convex at the mirror electrode E to form a focusing lens 303a. At this time, the grooves 303b on the first alignment film 303 for controlling the alignment direction of the liquid crystal are distributed at the protrusions. It should be noted that the protrusions can be strip-shaped along the direction of the groove 303a to facilitate manufacturing. It should be pointed out that the size ratio of the groove 303b relative to the mirror electrode E is only an indication, and does not represent the ratio in the actual product.

The above-mentioned focusing lens, in conjunction with the following rigorously designed illumination system, can condense the light irradiated onto it into a micro spot with a size smaller than the size of the mirror electrode. Referring to FIG. 3C, a series of parallel light beams with a certain angle enter a mirror electrode E through a focusing lens 303a. Assuming that the focal length f of the focusing lens 303a is 120 μm, the pixel size p corresponding to the mirror electrode E is 14 μm, and the maximum half angle β of the parallel beam is 3.5°, the image height a of the micro-spot formed by the mirror electrode is :

tan(β)=(a/2)/(f/2); a=2*(f/2)*tanβ=7.3μm;

That is, an image with a size of 7.3 μm appears in front of the mirror electrode E, and its size is about 1/2 of the pixel size.

Let W be the maximum half angle of the outgoing light, then:

tan(w)=((a+p)/2)/f=((7.3+14)/2)/60=0.1775, W=10.065°;

The calculation of the aperture value Fno is as follows:

Fno=1/(2tan(w))=2.8. (The influence of the refractive index of liquid crystal etc. is not considered)

That is, in the optical path system, the projection lens 205 only needs to use an aperture value of 2.8 to pass all the light. At the same time, the focal plane of the lens is no longer on the mirror electrode of the LCOS panel 203, but on the micro-spot array in front of the LCOS panel, so that an array of micro-spots with a much smaller area than the original mirror electrode is projected onto the surface of the photosensitive material , And finally imaged on the surface of the photosensitive material, forming an exposure spot.

Another benefit of convergence is that after convergence, although the area of the micro-spots is reduced, the brightness of the micro-spots is increased in the same proportion, so that when the micro-spot is finally imaged on the surface of the photosensitive material, the curing area is reduced and the curing time is shortened by the same proportion. After multiple exposures, the micro-spots will fill up all resin surfaces, which allows the present invention to improve projection resolution while maintaining the total exposure time and direct exposure required for curing to remain substantially unchanged.

In fact, due to possible manufacturing defects of the focusing lens, especially the existence of the diffraction effect of light, the spot size will be slightly larger than the actual calculation, and the shape of the spot may also become a circle, which requires the adjustment of the aforementioned parameters in actual experiments to Determine the final data.

FIG. 4A shows a structural diagram of another embodiment of the LCOS panel of the image exposure system shown in FIG. 2, and FIG. 4D shows an optical path diagram of the LCOS panel of FIG. 4A. 4A and 4B, the LCOS panel 203 may include a circuit substrate 401, a mirror electrode array 402, a first alignment film 403, a common electrode 404, a liquid crystal 405, a second alignment film 406, and a light-transmitting plate 407. A CMOS circuit may be provided on the circuit substrate 301, which includes a plurality of CMOS switches for controlling the operation of the LCOS panel 203 according to the control signal. The mirror electrode array 402 includes many mirror electrodes E, and each mirror electrode E corresponds to one pixel of the LCOS panel 203. The first alignment film 403 covers the mirror electrode array 402, which is a thin film having straight grooves, and serves to guide the arrangement direction of liquid crystal molecules. The second alignment film 406 covers the common electrode 404 and is opposite to the first alignment film 403. It is a thin film with straight strip-shaped grooves, and its role is to guide the arrangement direction of liquid crystal molecules. The common electrode 404 is opposite to the mirror electrode array 402, and they are separated by a certain distance. The common electrode 404 is a transparent electrode, and its material is, for example, ITO (Indium Tin Oxide). The liquid crystal 405 is located between the mirror electrode array 402 and the common electrode 404. When a voltage is applied to the mirror electrode array 402 and the common electrode 404, the molecules in the liquid crystal 405 are twisted by an angle between them, thereby changing the polarization direction of light passing therethrough. Each mirror electrode E in the mirror electrode array 402 may be applied with a different voltage, so that the twist angle of the liquid crystal molecules above each mirror electrode E is different. The mirror electrode E itself is still a mirror surface, which can reflect the light passing through the liquid crystal 405 and return it to its original path. Therefore, the liquid crystal on silicon panel 203 can adjust the state of the liquid crystal 405 according to the control signal, thereby changing the polarization direction of the light of the micro-spot M reflected by each mirror electrode E. The micro-spots reflected by the mirror electrodes E constitute an array of micro-spots with adjustable images. As shown in FIG. 4B, in this embodiment, the reflective surface of each mirror electrode E of the mirror electrode array 402 is set as a concave mirror, so that the light beam irradiated on the mirror electrode E can be condensed, so that the reflected micro-spot size s It is smaller than the pixel size corresponding to the mirror electrode E. In some embodiments, the pixel size corresponding to the mirror electrode E may be the size of the mirror electrode E itself.

With continued reference to FIG. 4B, the first alignment film 403 is correspondingly recessed at the concave mirror of each mirror electrode E of each mirror electrode array. In contrast, the second alignment film 406 is flat overall except for the groove. At this time, the grooves 403a for controlling the alignment direction of the liquid crystal on the first alignment film 403 are distributed in the recesses. It should be noted that the size ratio of the groove 403a relative to the mirror electrode E is merely an indication, and does not represent the ratio in the actual product.

In an embodiment, the mirror electrode E with a concave mirror can be formed by MEMS (micro-electromechanical system) layer-by-layer processing and ion polishing. As shown in FIG. 4C, a metal layer having depressions is formed layer by layer on the mirror electrode E, thereby forming a concave mirror.

In the embodiment of the present invention, each mirror electrode of the LCOS panel is designed as a concave mirror, and with the following strictly designed lighting system, the light irradiated thereon can be condensed into a micro spot with a size smaller than that of the mirror electrode. Referring to FIG. 4D, a series of parallel light beams with a certain angle enter a mirror electrode E having a concave mirror characteristic. Assuming that the focal length f of the concave mirror electrode E is 60 μm, the pixel size p corresponding to the mirror electrode E is 14 μm, and the maximum half-angle β of the parallel beam is 3.5°, the image height of the micro-spot formed by the reflection of the mirror electrode a is:

tan(β)=(a/2)/f; a=2*f*tanβ=7.3μm;

Let W be the maximum half angle of the outgoing light, then:

tan(w)=((a+p)/2)/f=((7.3+14)/2)/60=0.1775, W=10.065°;

The calculation of the aperture value Fno is as follows:

Fno=1/(2tan(w))=2.8.

Another benefit of convergence is that after the convergence, although the area of the micro-spots is reduced, the brightness of the micro-spots is increased by the same proportion, so that when the micro-spot is finally imaged on the surface of the photosensitive material, the curing area is reduced, and the curing time is shortened by the same proportion. After the second exposure, the micro-spots will fill up all the resin surfaces. At this time, the present invention improves the projection resolution and the total exposure time and direct exposure required for curing remain basically unchanged.

In fact, due to the possible manufacturing defects of the mirror electrode, especially the existence of the diffraction effect of light, the spot size will be slightly larger than the actual calculation, and the shape of the spot may also become a circle, which requires adjustment of the aforementioned parameters in the actual test to Determine the final data.

FIG. 5A shows a structural diagram of another embodiment of the LCOS panel of the image exposure system shown in FIG. 2, and FIG. 5B shows an optical path diagram of the LCOS panel of FIG. 5A (the mirror electrode reflection interface is developed into a direct light path diagram). 5A and 5B, the LCOS panel 203 may include a circuit substrate 501, a mirror electrode array 502, a first alignment film 503, a common electrode 504, a liquid crystal 505, a second alignment film 506, and a light-transmitting plate 507. A CMOS circuit may be provided on the circuit substrate 501, which includes a plurality of CMOS switches for controlling the operation of the LCOS panel 203 according to the control signal. The mirror electrode array 502 includes many mirror electrodes E, and each mirror electrode E corresponds to one pixel of the LCOS panel 203. The first alignment film 503 covers the mirror electrode array 502, which is a thin film with straight strip-shaped grooves, and functions to guide the arrangement direction of liquid crystal molecules. The second alignment film 506 covers the common electrode 504 and is opposite to the first alignment film 503. It is a thin film with straight strip-shaped grooves, and serves to guide the arrangement direction of liquid crystal molecules. The common electrode 504 is disposed opposite to the mirror electrode array 502, and they are separated by a certain distance. The common electrode 504 is a transparent electrode, and its material is, for example, ITO (Indium Tin Oxide). The liquid crystal 505 is located between the mirror electrode array 502 and the common electrode 504. When a voltage is applied to the mirror electrode array 502 and the common electrode 504, the molecules in the liquid crystal 505 will twist a certain angle between them, thereby changing the polarization direction of light passing therethrough. Each mirror electrode E in the mirror electrode array 502 may be applied with a different voltage, so that the twist angle of the liquid crystal molecules above each mirror electrode E is different. The mirror electrode E itself is still a mirror surface, which can reflect the light passing through the liquid crystal 505 and return it to its original path. Here, the reflection surface of the mirror electrode E may be a flat surface. Therefore, the liquid crystal on silicon panel 203 can adjust the state of the liquid crystal 505 according to the control signal, thereby changing the polarization direction of the light of the micro-spot M reflected by each mirror electrode E. The micro-spots reflected by each mirror electrode E constitute an array of micro-spots with adjustable patterns. In this embodiment, a focusing lens array 506 is provided on the incident side of the common electrode 504, each focusing lens 506a of the focusing lens array 506 corresponds to each mirror electrode E of the mirror electrode array 402, and each focusing lens 506a can converge to irradiate Corresponding to the light beam of the mirror electrode E, so that the size s of the reflected micro spot M of the mirror electrode E is smaller than the pixel size p of the mirror electrode E. In some embodiments, the pixel size corresponding to the mirror electrode E may be the size of the mirror electrode E itself.

Different from the previous embodiment, in this embodiment, the first alignment film 403 and the second alignment film 406 are flat except for the groove, and need not be configured to have a focusing effect.

In the embodiment of the present invention, the focusing effect of the focusing lens array 506 of the LCOS panel, combined with the following rigorously designed lighting system, can condense the light irradiated thereon into a micro spot with a size smaller than that of the mirror electrode. Referring to FIG. 5B (the mirror electrode reflection interface is expanded into a direct light path diagram), a parallel light beam with a certain angle passes through a focusing lens 506a, is reflected after entering the mirror electrode E, and exits after passing through the focusing lens 506a again Therefore, there are two lenses in FIG. 5B, called the first lens (left side in the figure) and the second lens (right side in the figure), respectively.

Assuming that the focal length of lens 506a is f, the diameter is 2p, p is the 1/2 pixel size corresponding to the mirror electrode, the distance from lens 506a to mirror electrode E is d, and the angle of incident light is β,

M is a low-light spot image passing through the first lens, and the image height is h ₁ .

h ₁ = f·tanβ

Consider light rays P ₁ →P ₂ →P ₃ →P ₄ , P ₂ /P ₃ are the intersection points of the light rays and the two lenses, k _i is the slope of each segment relative to the horizontal plane, and y _i is the height corresponding to P _i (intersection point Height), where i = 1, 2, 3, 4. So there are:

k ₁ =tanβ

y ₂ = -p

There are several special cases:

(1) d>f It is obvious that the light cone is converged and sent, and the aperture will be greater than 2p to the position of the second lens, adjacent pixels interfere with each other, this possibility does not exist (no practical value)

(2) 2d=f

At this time, y ₃ = 2d·tan β

Calculation of lens Fno1:

Fno1＝1/2k ₃

M is imaged by the second lens, and the image height is set to h ₂ . For the second lens, the object distance l=f-2d (as in the above figure, l<0).

According to the Gaussian imaging formula:

Calculate the magnification α:

Spot diameter:

Then trace a light ray Q1→Q2→Q3→Q4, k′ _i is the slope of each segment, y′ _i is the height (intersection height) corresponding to Q _i , i=1, 2, 3, 4.

k′ ₁ =tanβ

y′ ₂ = b

Lens Fno1 is:

Fno1＝1/2k' ₃

The comparison between Fno2 at this point and Fno1 calculated from P ₁ → P ₄ above should take the smaller absolute value as the Fno of the rear projection lens.

Based on the results of the above calculations, it is assumed that the focal length f of the focus lens 506a is 100 μm, the pixel size 2p corresponding to the focus lens 506a is 14 μm, the half angle β of the beam is 2.5°, and the distance between the focus lens and the reflective electrode is d 40μm, where f must be greater than d, then the image height a of the micro-spot formed by the focusing lens 506a is:

a=(f ² *tanβ)/(fd)=7.28μm

That is, an image with a size of 7.28 μm appears in front of the mirror electrode E, and its size is about 1/2 of the pixel size

The calculation of the aperture value Fno is as follows:

Select Fno1 as the system Fno.

Another advantage of convergence is that after the convergence, although the area of the micro-spot is reduced, the brightness of the micro-spot is increased by the same proportion. When the micro-spot is finally imaged on the surface of the photosensitive material, the curing area is reduced and the curing time is shortened by the same proportion. After the second exposure, the micro-spots will fill up all the resin surfaces. At this time, the present invention improves the projection resolution and the total exposure time and direct exposure required for curing remain basically unchanged.

In fact, due to possible manufacturing defects of the focusing lens 506a, especially the existence of the diffraction effect of light, the spot size will be slightly larger than the actual calculation, and the shape of the spot may also become a circle, which requires adjustment of the aforementioned parameters in actual experiments. To determine the final data.

FIG. 6 shows an image formed by the image exposure system of an embodiment of the present invention once exposed on the surface of a photosensitive material. For comparison, if the light is directly imaged through the mirror electrode (the reflecting surface is a flat surface), since the gap between the mirror electrodes is small, the obtained image will occupy almost the entire projection area (see FIG. 6). Comparing FIG. 6 and FIG. 7, it can be seen that after the convergence of the mirror electrode or the focusing lens which is a concave mirror, the size of the micro-spot in the image is reduced. By precisely designing the shape of the illumination system and the mirror electrode (or focusing lens), the size of the imaging spot can be controlled. For example, the ratio of the imaging spot size to the pixel size (such as the size of the mirror electrode) can be 1:2, that is, the area ratio can be 1:4.

In addition, the ratio of the imaging spot size to the pixel size can be about 1:3 or 1:4. The reason for the integer multiple here is that when considering the subsequent micro-displacement, a new micro-spot needs to be inserted in the blank portion of each micro-spot.

As shown in FIG. 7, in the image of one exposure on the surface of the photosensitive material, there are blank spaces between the light spots. To this end, these gaps are filled by multiple exposures, so that the light spot covers the entire surface of the photosensitive material.

As shown in FIG. 2, a micro-displacement drive mechanism 204 is connected to the LCOS panel 203. The micro-displacement driving mechanism 204 can drive the LCOS panel 203 to move in the x direction and the y direction to finely adjust the position of the micro spot array projected onto the surface of the photosensitive material. Here, the x and y directions are on the same plane, and this plane is perpendicular to the optical axis z of the image exposure system. When the micro-displacement drive mechanism does not drive the displacement of the LCOS panel 203, the micro-spot array of the LCOS panel 203 is imaged at the first position on the surface of the photosensitive material; when the micro-displacement drive mechanism 204 drives the LCOS panel 203 in one direction (x or y direction) During displacement, the entire micro-spot array of the LCOS panel 203 will be slightly displaced with the LCOS panel 203, thereby imaging at a position other than the first position of the photosensitive material surface 220.

The above displacement can be combined with multiple exposures to superimpose the spot images of each exposure so that the spot covers the surface of the photosensitive material. Specifically, the light source 201 may be exposed multiple times, and at each exposure, the LCOS panel 203 is commanded to perform displacement to project the micro-spot array of each exposure to different positions on the surface of the photosensitive material. FIG. 8 shows an image formed by exposure of the image exposure system of the embodiment of the present invention four times on the surface of the photosensitive material. Referring to FIG. 8, at the first exposure, the projected image A is formed; at the second exposure, the micro-displacement array is slightly moved because the micro-displacement drive mechanism 204 moves a distance of 1/2 pixel in the x direction. Move in the horizontal direction in the figure and project into the gap between the two rows of micro-spots to form a projected image B; during the third exposure, the micro-displacement drive mechanism 204 moves in the y direction, so that the micro-spot array slightly follows the figure The vertical direction in is moved by a distance of 1/2 pixel, projected into the gap between two rows of micro-spots to form a projected image C; similarly, a projected image D is formed. The projected image D has covered the surface of the photosensitive material.

The micro-displacement driving mechanism 204 may be piezoelectric ceramic. In actual implementation, the controller of the image exposure system 200 can be used to order the light source 201 to perform multiple exposures, and at the same time, the micro-displacement drive mechanism 204 can be ordered to coordinate the movement in both x and y directions during each exposure.

The projection lens 205 is arranged between the LCOS panel 203 and the photosensitive material surface 220 of the three-dimensional printing device, and projects the micro-spot array reflected by the LCOS panel 203 onto the photosensitive material surface.

It should be noted that although the superposition of the micro-spot arrays of each exposure covers the surface 220 of the photosensitive material, the positions of the micro-spot arrays of each exposure on the surface of the photosensitive material may not substantially overlap each other. This is achieved by controlling the ratio of the pixel size to the spot size to be an integer, and the displacement step is exactly the spot size. This setting, which basically does not overlap each other, can avoid a decrease in resolution. It can be understood that considering the light diffraction effect and other factors, the slight overlap helps to compensate for the lack of the non-rectangular edge portion of the micro-spot. Therefore, there is no requirement that there is no overlap between the micro-flares. In addition, although the superimposition of the micro-spot array covers the surface of the photosensitive material, it can be understood that not every position in the micro-spot array is controlled by an image, but there may be dark spots.

In the embodiment of the present invention, the micro-spot array of each exposure contains different image information. Taking FIG. 8 as an example, in the projection pattern D, the four micro-spots D1 in the virtual frame contain mutually different image information. This means that the resolution of the projected pattern becomes 4 times the original. Therefore, the accuracy of 3D printing is significantly improved. These different image information can be from 4 different image files that can compose a complete image, or can be 4 sub-images extracted from one image of the same image file after processing. Taking the example shown in FIG. 9, the image contains 4*4=16 pixels A1-A4, B1-B4, C1-C4, and D1-D4. Shaded pixels indicate that exposure is required, and unshaded pixels indicate that no need exposure. Here, pixel groups {A1, A3, C1, C3}, {A2, A4, C2, C4}, {B1, B3, D1, D3}, and {B2, B4, D2, can be extracted from the image D4}, used as 4 sub-images for 4 exposures respectively. In contrast, the image used by traditional printing equipment has a pixel size of at least 4 pixels as shown in Figure 9, such as {A1, A2, B1, B2}, so its resolution is significantly lower .

In addition, through experiments, it has been found that this method of time-sharing different pixels of the photosensitive material through multiple exposures has other advantages. Specifically, when the photo-curable material is cured, the material will shrink by a certain amount. When a large-area photo-curable material is simultaneously photo-cured, a large continuous internal stress will be generated, causing the cured object to warp and deform. In the method of the above embodiment of the present invention, by allowing different pixels to be cured at different times, the influence of the pixels on the surrounding pixels during curing shrinkage can be reduced, thereby improving the degree of warpage and deformation of the cured object. Referring to FIG. 8, firstly, a plurality of pixels arranged at intervals on the photosensitive material are exposed and cured to form a projected image A. The surrounding area pulled by each pixel during curing shrinkage is still a liquid photosensitive material, and the variability of the liquid material cancels out The effect of pulling avoids the accumulation of internal stress; then, the second exposure and curing are performed to form the projected image B. The pixels (even columns) cured this time are still liquid photosensitive materials in both the upper and lower directions, so these two The variability of the liquid material in each direction counteracts the effect of pulling; then the third exposure is cured to form the projected image C. The cured pixels (even lines) are still liquid photosensitive material around the left direction, so this direction The volatility of the liquid material counteracts the effect of pulling; finally, the fourth exposure and curing are performed to form the projected image D. Only the solidified photosensitive material around the pixels cured this time. But at this time, only 1/4 of the material is cured, and the characteristic of the pixel after focusing is that the energy is distributed according to a Gaussian curve, and the middle is brighter than the surrounding, so that when curing occurs, the middle of the pixel will cure faster than the edge. The internal stress at the time can also be absorbed by the surrounding uncured resin, and the internal stress accumulated when fully cured is already very small. More importantly, because only pixels separated from each other are curing at the same time, adjacent pixels will not be cured at the same time, which avoids the pulling of each pixel when curing at the same time.

In a preferred embodiment, referring to FIG. 13, after the first exposure and curing are performed to form the projection image A, the second exposure and curing are then performed to form the projection image B. The pixels cured in the projected image B and the pixels cured in the projected image A are located diagonally and are not adjacent to each other. Therefore, the pixels cured this time are still liquid photosensitive materials in all four directions, and the variability of the liquid material Offset the effect of pulling. Then the third exposure and curing to form the projected image C and the fourth exposure and curing to form the projected image D are the same as the embodiment shown in FIG. 10, and will not be expanded here.

Similarly, when performing 9 exposures or 16 exposures, it is also possible to give priority to the exposure of several projection images that are not adjacent to each other, so as to minimize the influence of mutual pulling.

In the above example, when the size of the micro spot is controlled to 1/2 of the pixel size, four exposures are performed. It can be understood that when the micro-spot is controlled to 1/3 of the pixel size, 9 exposures can be performed, when the micro-spot is controlled to 1/4 of the pixel size, 16 exposures can be performed, and so on.

FIG. 10 shows an image exposure system of a 3D printing apparatus according to another embodiment of the present invention. In the image exposure system 200' of this embodiment, the aforementioned micro-displacement drive mechanism 204 is replaced with a deflection lens 206. The deflection lens 206 may be arranged at any position in the optical path from the LCOS panel 203 to the photosensitive resin 220, and is generally arranged near the projection lens 205. The deflection lens 206 can deflect around at least one rotation axis to fine-tune the position of the light beam projected onto the surface of the photosensitive material. The aforementioned rotation axes are all perpendicular to the optical axis z of the image exposure system. When the deflection lens 206 and the LCOS panel 203 are parallel (perpendicular to the optical axis z), the light irradiates the deflection lens 206 vertically (as shown in FIG. 11), and there is no refraction When the phenomenon occurs, the light directly passes through the deflection lens 206; if the deflection lens 206 is inclined at an angle around a rotation axis, the light from the air entering the deflection lens 206 will be refracted, and the light from the deflection lens 206 will be refracted again when entering the air. At the same angle and in the opposite direction, the refracted light will proceed in the original direction, but a slight displacement will occur (as shown in Figure 12). In addition, this rotation axis may be a rotation axis y that is located in a plane including the rotation axis x and perpendicular to the optical axis z, and perpendicular to the rotation axis x. In the embodiment of the present invention, the deflection lens 206 may be able to deflect about the rotation axis x as well as about the rotation axis y. The number of deflection lenses 206 may be one, or two or more.

Similarly, the above-mentioned deflection can be combined with multiple exposures to superimpose the beam images of each exposure so that the light spot covers the surface of the photosensitive material. Specifically, the light source 201 may be exposed to multiple exposures. At each exposure, the deflection lens 206 is commanded to deflect to project the beam images of each exposure to different positions on the surface of the photosensitive material.

In actual implementation, the controller of the image exposure system 200' may be used to command the light source 201 to perform multiple exposures, and at the same time, the deflection lens 206 is commanded to perform deflection in both the x and y directions at each exposure.

Next, the principle that the exposure brightness is favorable for the photosensitive of the photosensitive material will be explained. After receiving a certain amount of light, the photosensitive material will be cured within a certain time, this time is called the curing time. The power of light irradiation, that is, the light energy received by the photosensitive material in a unit time, will significantly affect the curing time. In theory, the energy required to cure a certain area of photosensitive material can be expressed as:

W=P*t, P is the light power irradiated on the resin, and t is the exposure time.

That is, the same energy can be achieved by increasing the optical power to reduce the exposure time or reducing the optical power to increase the exposure time, which is called the “reciprocity law”. However, there is a case of reciprocity law distortion in the photosensitive resin.

Fig. 14 shows the relationship between the energy required for curing the photosensitive resin and the light power. As shown in FIG. 14, the x-axis represents light power and the y-axis represents energy W required for curing. The curve represents the energy required for curing a certain area of photosensitive material under different light powers. When the light power is below P ₀ , the energy W is required to be infinite, since t=W/P, that is, infinite time is required. The curve contains a linear segment (the part close to 45° in the figure) and a nonlinear segment (the part close to vertical in the figure). In the linear section, as the light power increases, the required curing time is inversely proportional to the light power, and the energy required for curing is basically unchanged. At this time, it basically conforms to the above "reciprocity law"; in the nonlinear section, as the light power decreases Smaller, the required curing time increases rapidly nonlinearly, and the energy required for curing increases nonlinearly. Among them, in the area close to P ₀ , the slight reduction of the light power requires a large increase in exposure time to cure the resin to the same degree. Since the wavelength of light required by the photosensitive resin is below 430nm, the excessively strong light of this wavelength is harmful to the liquid crystal panel. In the present invention, after the liquid crystal imaging spot is reduced to, for example, 1/4, the brightness is 4 times the original, so that the exposure enters a relatively linear segment, thereby greatly reducing the curing time of the photosensitive material and increasing the exposure speed. At the same time, the total energy W required for curing (which is also the light energy passing through the liquid crystal panel) is reduced, and the life of the liquid crystal panel is extended.

In some embodiments, the controllers of the image exposure systems 200 and 200' may include one or more hardware processors, such as a microcontroller, microprocessor, reduced instruction set computer (RISC), application specific integrated circuit (ASIC), Application specific instruction integrated processor (ASIP), central processing unit (CPU), graphics processing unit (GPU), physical processing unit (PPU), microcontroller unit, digital signal processor (DSP), field programmable gate array ( FPGA), advanced RISC machine (ARM), programmable logic device (PLD), any circuit or processor capable of performing one or more functions, or a combination of one or more of them. For example, the controller includes a processor that loads and executes computer instructions in the memory to implement the control steps of the embodiments of the present invention.

The above-mentioned embodiments of the present invention achieve focusing by setting the mirror electrode of the LCOS panel as a concave mirror or adding a condenser lens. Combined with multiple exposures and the micro-displacement of the LCOS panel, the surface of the photosensitive material can be filled with the exposure spot, and then each time Exposure uses different imaging information, which can improve the resolution of imaging and thus the accuracy of printing.

Although the present invention has been described with reference to the current specific embodiments, those of ordinary skill in the art should realize that the above embodiments are only used to illustrate the present invention and can be made without departing from the spirit of the present invention There are various equivalent changes or substitutions. Therefore, as long as the changes and modifications to the above-mentioned embodiments are within the spirit and scope of the present invention, they will fall within the scope of the claims of the present application.

Claims

An image exposure system for 3D printing equipment, including:

A silicon-based liquid crystal panel includes a mirror electrode array, a common electrode, a liquid crystal between the mirror electrode array and the common electrode, a first alignment film between the mirror electrode array and the liquid crystal, and a A second alignment film between the liquid crystal and the common electrode, the first alignment film protrudes at each mirror electrode corresponding to the mirror electrode array to form a focusing lens, and each focusing lens can converge to illuminate the corresponding mirror Light from the electrode, so that the size of the reflected micro-spot of the mirror electrode is smaller than the pixel size corresponding to the mirror electrode, wherein the liquid crystal on silicon panel is used to adjust the state of the liquid crystal according to the control signal, thereby changing each The polarization direction of the light reflected by the mirror electrode array;

The light source generates a light shining on the silicon-based liquid crystal panel;

A polarized beam splitter, used to filter the light generated by the light source into polarized light to illuminate the silicon-based liquid crystal panel, and filter out light of a predetermined polarization direction from the light reflected by the mirror electrode array;

A projection lens is provided in the exit direction of the polarized beam splitter, so that a micro-spot array composed of micro-spots reflected by each mirror electrode is projected onto the surface of the photosensitive material;

A micro-displacement drive mechanism, connected to the silicon-based liquid crystal panel, can drive the silicon-based liquid crystal panel to move in a first direction and a second direction perpendicular to each other to finely adjust the position of the micro-spot array projected onto the surface of the photosensitive material ;as well as

The controller instructs the light source to perform multiple exposures, and in each exposure instructs the micro-displacement driving mechanism to move to project the micro-spot array of each exposure to different positions on the surface of the photosensitive material.
The image exposure system of the 3D printing apparatus according to claim 1, wherein the images formed by the micro-spot arrays of each exposure on the surface of the photosensitive material do not overlap each other.
The image exposure system of the 3D printing apparatus according to claim 1, wherein the image formed by the micro-spot array of each exposure covers the surface of the photosensitive material.
The image exposure system of the 3D printing apparatus according to claim 1, wherein the micro-spot array of each exposure contains different image information.
The image exposure system of the 3D printing apparatus according to claim 1, wherein, assuming that the focal length of each focusing lens is f, the pixel size corresponding to each focusing lens is p, and the half angle of the light incident on each micromirror Is β, the image height of the micro-spot is a, and the maximum half-angle of the outgoing light is W, then:

tan(β)=(a/2)/(f/2);

tan(w)=((a+p)/2)/(f/2);

Fno = 1/(2tan(w)).
The image exposure system of the 3D printing apparatus according to claim 1, wherein the ratio of the size of the micro-spot to the pixel area corresponding to the mirror electrode is approximately 1:4, 1:9 or 1:16 .
The image exposure system of the 3D printing apparatus according to claim 6, wherein the number of exposure times of the light source is 4, 9 or 16 times.
An image exposure system for 3D printing equipment, including:

A silicon-based liquid crystal panel includes a mirror electrode array, a common electrode, a liquid crystal between the mirror electrode array and the common electrode, a first alignment film between the mirror electrode array and the liquid crystal, and a A second alignment film between the liquid crystal and the common electrode, each mirror electrode of the mirror electrode array is a concave mirror, which can condense the light irradiated thereon, so that the reflected micro-spot size is smaller than that corresponding to the mirror electrode Pixel size, wherein the silicon-based liquid crystal panel is used to adjust the state of the liquid crystal according to a control signal, thereby changing the polarization direction of each light reflected by the mirror electrode array;

The light source generates a light shining on the silicon-based liquid crystal panel;

A polarized beam splitter, used to filter the light generated by the light source into polarized light to illuminate the silicon-based liquid crystal panel, and filter out light of a predetermined polarization direction from the light reflected by the mirror electrode array;

A projection lens is provided in the exit direction of the polarized beam splitter, so that a micro-spot array composed of micro-spots reflected by each mirror electrode is projected onto the surface of the photosensitive material;

A micro-displacement drive mechanism, connected to the silicon-based liquid crystal panel, can drive the silicon-based liquid crystal panel to move in a first direction and a second direction perpendicular to each other to finely adjust the position of the micro-spot array projected onto the surface of the photosensitive material ;as well as

The controller instructs the light source to perform multiple exposures, and in each exposure instructs the micro-displacement driving mechanism to move to project the micro-spot array of each exposure to different positions on the surface of the photosensitive material.
The image exposure system of the 3D printing apparatus according to claim 8, wherein the images formed by the micro-spot arrays of each exposure on the surface of the photosensitive material do not overlap each other.
The image exposure system of the 3D printing apparatus according to claim 8, wherein the image formed by the micro-spot array of each exposure covers the surface of the photosensitive material.
The image exposure system of the 3D printing apparatus according to claim 8, wherein the size of the micro-spot is less than, equal to or greater than half the pixel size corresponding to the mirror electrode.
The image exposure system of the 3D printing apparatus according to claim 8, wherein, assuming that the focal length of each mirror electrode concave mirror is f, the pixel size corresponding to each mirror electrode is p, half of the light incident on each mirror electrode If the angle is β, the image height of the micro-spot is a, and the maximum half-angle of the outgoing light is W, then:

tan(β)=(a/2)/f;

tan(w)=((a+p)/2)/f;

Fno = 1/(2tan(w)).
The image exposure system of the 3D printing apparatus according to claim 8, wherein the micro-spot array of each exposure contains different image information.
The image exposure system of a 3D printing device according to claim 8, wherein the ratio of the size of the micro-spot to the pixel area corresponding to the mirror electrode is 1:4, 1:9 or 1:16.
The image exposure system of the 3D printing apparatus according to claim 14, wherein the number of exposure times of the light source is 4, 9 or 16 times.
The image exposure system of the 3D printing apparatus according to claim 8, wherein the first alignment film is correspondingly recessed at each mirror electrode concave mirror of the mirror electrode array.
An image exposure system for 3D printing equipment, including:

A silicon-based liquid crystal panel includes a mirror electrode array, a common electrode, liquid crystal between the mirror electrode array and the common electrode, a first alignment film between the mirror electrode array and the liquid crystal, and A second alignment film between the liquid crystal and the common electrode, and a focusing lens array on the incident side of the common electrode, each focusing lens of the focusing lens array corresponds to each mirror electrode of the mirror electrode array, Each focusing lens can condense the light irradiated to the corresponding mirror electrode, so that the reflected micro spot size of the mirror electrode is smaller than the pixel size corresponding to the mirror electrode, wherein the liquid crystal on silicon panel is used to adjust according to the control signal The state of the liquid crystal, thereby changing the polarization direction of the light reflected by the mirror electrode array;

The light source generates a light shining on the silicon-based liquid crystal panel;

A polarized beam splitter, used to filter the light generated by the light source into polarized light to illuminate the silicon-based liquid crystal panel, and filter out light of a predetermined polarization direction from the light reflected by the mirror electrode array;

A projection lens is provided in the exit direction of the polarized beam splitter, so that the micro-spot array is projected onto the surface of the photosensitive material;

A micro-displacement drive mechanism, connected to the silicon-based liquid crystal panel, can drive the silicon-based liquid crystal panel to move in a first direction and a second direction perpendicular to each other to finely adjust the position of the micro-spot array projected onto the surface of the photosensitive material ;as well as

The controller instructs the light source to perform multiple exposures, and in each exposure instructs the micro-displacement driving mechanism to move to project the micro-spot array of each exposure to different positions on the surface of the photosensitive material.
The image exposure system of the 3D printing apparatus according to claim 17, wherein the images formed by the micro-spot array of each exposure on the surface of the photosensitive material do not completely overlap each other.
The image exposure system of the 3D printing apparatus according to claim 17, wherein the image formed by the micro-spot array of each exposure covers the surface of the photosensitive material.
The image exposure system of the 3D printing apparatus according to claim 17, wherein the micro-spot array of each exposure contains different image information.
The image exposure system of the 3D printing apparatus according to claim 17, wherein the focal length of each focusing lens is f, the pixel size corresponding to each focusing lens is p, and the distance between the focusing lens and the corresponding reflective electrode is d, the half-angle of the light incident on each micromirror is β, the image height of the micro-spot is a, f>d, then satisfy:

a=(f 2 *tanβ)/(fd)

Among them, Fno1 or Fno2 with the largest absolute value is Fno.
The image exposure system of the 3D printing apparatus according to claim 17, wherein the size of the micro-spot is less than, equal to or greater than half the pixel size corresponding to the mirror electrode.
The image exposure system of the 3D printing apparatus according to claim 17, wherein the ratio of the size of the micro-spot to the pixel area corresponding to the mirror electrode is 1:4, 1:9 or 1:16.
The image exposure system of the 3D printing apparatus according to claim 23, wherein the number of exposure times of the light source is 4, 9 or 16 times.
An image exposure system for 3D printing equipment, including:

A silicon-based liquid crystal panel includes a mirror electrode array, a common electrode, a liquid crystal between the mirror electrode array and the common electrode, a first alignment film between the mirror electrode array and the liquid crystal, and a A second alignment film between the liquid crystal and the common electrode, the alignment film protruding at each mirror electrode corresponding to the mirror electrode array to form a focusing lens, and each focusing lens can converge to irradiate the corresponding mirror electrode Light, so that the size of the reflected micro-spot of the mirror electrode is smaller than the pixel size corresponding to the mirror electrode, wherein the silicon-based liquid crystal panel is used to adjust the state of the liquid crystal according to a control signal, thereby changing the mirror The polarization direction of the light reflected by the electrode array;

The light source generates a light shining on the silicon-based liquid crystal panel;

A polarized beam splitter, used to filter the light generated by the light source into polarized light to illuminate the silicon-based liquid crystal panel, and filter out light of a predetermined polarization direction from the light reflected by the mirror electrode array;

A projection lens is provided in the exit direction of the polarized beam splitter, so that a micro-spot array composed of micro-spots reflected by each mirror electrode is projected onto the surface of the photosensitive material;

A deflection lens is arranged between the liquid crystal on silicon substrate and the surface of the photosensitive material, and the deflection lens can be deflected around at least one rotation axis perpendicular to the optical axis of the projection lens to fine-tune the projection of the micro-spot array to The position of the surface of the photosensitive material; and

The controller commands the light source to perform multiple exposures, and commands the deflection lens to move at each exposure to project the micro-spot array of each exposure to different positions on the surface of the photosensitive material.
An image exposure system for 3D printing equipment, including:

A silicon-based liquid crystal panel includes a mirror electrode array, a common electrode, a liquid crystal between the mirror electrode array and the common electrode, a first alignment film between the mirror electrode array and the liquid crystal, and a A second alignment film between the liquid crystal and the common electrode, each mirror electrode of the mirror electrode array is a concave mirror, which can condense the light irradiated thereon, so that the reflected micro-spot size is smaller than that corresponding to the mirror electrode Pixel size, wherein the silicon-based liquid crystal panel is used to adjust the state of the liquid crystal according to a control signal, thereby changing the polarization direction of light reflected by the mirror electrode array;

The light source generates a light shining on the silicon-based liquid crystal panel;

A polarized beam splitter, used to filter the light generated by the light source into polarized light to illuminate the silicon-based liquid crystal panel, and filter out light of a predetermined polarization direction from the light reflected by the mirror electrode array;

A projection lens is provided in the exit direction of the polarized beam splitter, so that a micro-spot array composed of micro-spots reflected by each mirror electrode is projected onto the surface of the photosensitive material;

A deflection lens is arranged between the liquid crystal on silicon substrate and the surface of the photosensitive material, and the deflection lens can be deflected around at least one rotation axis perpendicular to the optical axis of the projection lens to fine-tune the projection of the micro-spot array to The position of the surface of the photosensitive material; and

The controller commands the light source to perform multiple exposures, and commands the deflection lens to move at each exposure to project the micro-spot array of each exposure to different positions on the surface of the photosensitive material.
An image exposure system for 3D printing equipment, including:

A silicon-based liquid crystal panel includes a mirror electrode array, a common electrode, liquid crystal between the mirror electrode array and the common electrode, a first alignment film between the mirror electrode array and the liquid crystal, and A second alignment film between the liquid crystal and the common electrode and a focusing lens array on the incident side of the common electrode, each focusing lens of the focusing lens array corresponds to each mirror electrode of the mirror electrode array, each A focusing lens can condense the light irradiated to the corresponding mirror electrode, so that the reflected micro spot size of the mirror electrode is smaller than the pixel size corresponding to the mirror electrode, wherein the silicon-based liquid crystal panel is used to adjust the The state of the liquid crystal, thereby changing the polarization direction of the light reflected by the mirror electrode array;

The light source generates a light shining on the silicon-based liquid crystal panel;

A polarized beam splitter, used to filter the light generated by the light source into polarized light to illuminate the silicon-based liquid crystal panel, and filter out light of a predetermined polarization direction from the light reflected by the mirror electrode array;

A projection lens is provided in the exit direction of the polarized beam splitter, so that the micro-spot array is projected onto the surface of the photosensitive material;

A deflection lens is arranged between the liquid crystal on silicon substrate and the surface of the photosensitive material, and the deflection lens can be deflected around at least one rotation axis perpendicular to the optical axis of the projection lens to fine-tune the projection of the micro-spot array to The position of the surface of the photosensitive material; and

The controller instructs the light source to perform multiple exposures, and in each exposure instructs the micro-displacement driving mechanism to move to project the micro-spot array of each exposure to different positions on the surface of the photosensitive material.
A photo-curing 3D printing device comprising the image exposure system according to any one of claims 1-27.