Light-curing 3D printing equipment and image exposure system thereof

Abstract

The present invention relates to an image exposure system of a 3D printing device, which uses a silicon-based liquid crystal panel as a surface array image source. The silicon-based liquid crystal panel comprises a mirror electrode array, a common electrode, a liquid crystal located between the mirror electrode array and the common electrode, a first alignment film located between the mirror electrode array and the liquid crystal, and a second alignment film located between the liquid crystal and the common electrode, wherein the first alignment film is raised at each mirror electrode corresponding to the mirror electrode array to form a focusing lens, and each focusing lens can converge the light irradiated to the corresponding mirror electrode, so that the micro-spot size reflected by 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, so as to change the polarization direction of each light reflected by the mirror electrode array.

Description

Technical Field

[0001] The present invention relates to a photocurable 3D printing device, and in particular to an image exposure system of the photocurable 3D printing device. Background Art

[0002] 3D printing technology is based on a computer three-dimensional design model. Through software layered discreteness and CNC molding systems, laser beams, hot melt nozzles and other methods are used to stack and bond special materials such as metal powder, ceramic powder, plastic, and cell tissue layer by layer, and finally stack and shape them to produce physical products. Unlike traditional manufacturing industries that use mechanical processing methods such as molds, turning and milling to shape and cut raw materials to finally produce finished products, 3D printing transforms three-dimensional entities into several two-dimensional planes, and produces by processing materials and stacking them layer by layer, greatly reducing the complexity of manufacturing. This digital manufacturing model does not require complex processes, large machine tools, or a large number of manpower. Parts of any shape can be generated directly from computer graphics data, allowing production and manufacturing to extend to a wider range of production populations.

[0003] At present, the molding methods of 3D printing technology are still evolving, and the materials used are also diverse. Among various molding methods, light curing is a relatively mature method. Light curing uses the principle that photosensitive resin is cured after being irradiated with ultraviolet light to perform material cumulative molding. It has the characteristics of high molding accuracy, good surface finish, and high material utilization rate.

[0004] Figure 1 The basic structure of a photocurable 3D printing device is shown. This 3D printing device 100 includes a material tank 110 for accommodating photosensitive resin, an image exposure system 120 for curing the photosensitive resin, and a lifting platform 130 for connecting the molded workpiece. The image exposure system 120 is located above the material tank 110, and can irradiate a light 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 a light beam image to cure a layer of photosensitive resin, the lifting platform 130 will drive the formed layer of cured photosensitive resin to slightly descend, and use the scraper 131 to evenly spread the photosensitive resin on the top surface of the cured workpiece, waiting for the next irradiation. In this way, a three-dimensional workpiece formed layer by layer will be obtained.

[0005] The image exposure system 120 may use laser forming technology, digital light processing (DLP), or liquid crystal on silicon (LCOS) projection technology.

[0006] Laser forming technology uses laser scanning equipment to scan point by point. However, due to the characteristics of photosensitive resin, the laser power cannot 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 a slow forming speed.

[0007] LCOS is a matrix liquid crystal display device based on reflection mode and with very small pixel size. This matrix is ​​made on a silicon chip using CMOS technology. The matrix circuit provides voltage between the electrode of each pixel and the common transparent electrode, which are separated by a thin layer of liquid crystal. The electrode of the pixel is also a reflector (hereinafter referred to as the mirror electrode), and the electrodes of all pixels together form a reflective mirror surface. The electronic circuit that controls the image formation is made on the silicon chip, and changes the polarization direction of the incident polarized light of each pixel by controlling the state of the liquid crystal molecules. The light reflected by the mirror electrode is separated from the incident light by optical methods and is magnified and imaged onto the object by the projection objective. Finally, the entire reflection projects the desired beam image. When LCOS is used in 3D printing, its development is restricted by limited resolution. For example, the current highest resolution commonly used by LCOS is usually 1920*1080. However, this resolution can only produce objects with an area of ​​192*108mm with the commonly used accuracy of 0.1mm in 3D printing, which obviously limits its application. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a light-curing 3D printing device and an image exposure system thereof.

[0009] 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, comprising: a silicon-based liquid crystal panel, including a mirror electrode array, a common electrode, a liquid crystal located between the mirror electrode array and the common electrode, a first alignment film located between the mirror electrode array and the liquid crystal, and a second alignment film located between the liquid crystal and the common electrode, wherein the first alignment film is raised at each mirror electrode corresponding to the mirror electrode array to form a focusing lens, and each focusing lens can converge the light irradiated to the corresponding mirror electrode, so that the micro-spot size reflected by 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 polarization direction of each light reflected by the mirror electrode array; a light source, generating a light beam which irradiates the silicon-based liquid crystal panel; a polarized light splitter, which is used to filter the light generated by the light source into polarized light to irradiate 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, which is arranged in the exit direction of the polarized light 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 driving mechanism, which is connected to the silicon-based liquid crystal panel and can drive the silicon-based liquid crystal panel to move in a first direction and a second direction perpendicular to each other, so as to fine-tune the position where the micro-spot array is projected onto the surface of the photosensitive material; and a controller, which commands the light source to perform multiple exposures, and commands the micro-displacement driving mechanism to move during each exposure, so as to project the micro-spot array of each exposure onto different positions on the surface of the photosensitive material.

[0010] In one embodiment of the present invention, the images formed by the micro-spot arrays of each exposure on the surface of the photosensitive material do not overlap with each other.

[0011] In one embodiment of the present invention, the image formed by the micro-spot array of each exposure covers the entire surface of the photosensitive material.

[0012] In one embodiment of the present invention, the micro-spot arrays of each exposure contain different image information.

[0013] In one embodiment of the present invention, assuming 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, the image height of the micro spot is a, and the maximum half angle of the emitted light is W, then:

[0014] tan(β)=(a / 2) / (f / 2);

[0015] tan(w)=((a+p) / 2) / (f / 2);

[0016] Fno = 1 / (2tan(w)).

[0017] The present invention also proposes an image exposure system for a 3D printing device, comprising: a silicon-based liquid crystal panel, comprising a mirror electrode array, a common electrode, a liquid crystal located between the mirror electrode array and the common electrode, a first alignment film located between the mirror electrode array and the liquid crystal, and a second alignment film located between the liquid crystal and the common electrode, each mirror electrode of the mirror electrode array being a concave mirror, capable of converging the light irradiated thereon so that the size of the reflected micro-spot 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 polarization direction of each light reflected by the mirror electrode array; a light source, generating a light irradiated onto the silicon-based liquid crystal panel; a polarized light 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 with a predetermined polarization direction from the light reflected by the mirror electrode array; a projection lens, arranged in the exit direction of the polarized light splitter, so that the micro-spot array composed of the 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, capable of driving the silicon-based liquid crystal panel to move in a first direction and a second direction perpendicular to each other, so as to fine-tune the position where the micro-spot array is projected onto the surface of the photosensitive material; and a controller, commanding the light source to perform multiple exposures, and commanding the micro-displacement drive mechanism to move during each exposure, so as to project the micro-spot array of each exposure onto different positions on the surface of the photosensitive material.

[0018] In one embodiment of the present invention, the images formed by the micro-spot arrays of each exposure on the surface of the photosensitive material do not overlap with each other.

[0019] In one embodiment of the present invention, the image formed by the micro-spot array of each exposure covers the entire surface of the photosensitive material.

[0020] In one embodiment of the present invention, the size of the micro light spot is smaller than, equal to, or larger than half of the pixel size corresponding to the mirror electrode.

[0021] In one embodiment of the present invention, assuming 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, the image height of the micro spot is a, and the maximum half angle of the emitted light is W, then:

[0022] tan(β)=(a / 2) / f;

[0023] tan(w)=((a+p) / 2) / f;

[0024] Fno = 1 / (2tan(w)).

[0025] In one embodiment of the present invention, the first alignment film is correspondingly recessed at each mirror electrode concave mirror of the mirror electrode array.

[0026] The present invention also proposes an image exposure system for a 3D printing device, comprising: a silicon-based liquid crystal panel, comprising a mirror electrode array, a common electrode, a liquid crystal located between the mirror electrode array and the common electrode, a first alignment film located between the mirror electrode array and the liquid crystal, a second alignment film located between the liquid crystal and the common electrode, and a focusing lens array located 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 converge the light irradiated to the corresponding mirror electrode, so that the micro-spot size reflected by 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 polarization direction of the light reflected by the mirror electrode array A light source, generating a light beam that irradiates the silicon-based liquid crystal panel; a polarized light splitter, used to filter the light generated by the light source into polarized light to irradiate 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, arranged in the exit direction of the polarized light 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, capable of driving the silicon-based liquid crystal panel to move in a first direction and a second direction perpendicular to each other, so as to fine-tune the position where the micro-spot array is projected onto the surface of the photosensitive material; and a controller, commanding the light source to perform multiple exposures, and commanding the micro-displacement drive mechanism to move during each exposure, so as to project the micro-spot array of each exposure onto different positions on the surface of the photosensitive material.

[0027] In one embodiment of the present invention, the images formed by the micro-spot arrays of each exposure on the surface of the photosensitive material do not completely overlap with each other.

[0028] In one embodiment of the present invention, the image formed by the micro-spot array of each exposure covers the entire surface of the photosensitive material.

[0029] In one embodiment of the present invention, the micro-spot arrays of each exposure contain different image information.

[0030] In one embodiment of the present invention, assuming 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, the half angle of the light incident on each micromirror is β, the image height of the micro spot is a, and f>d, then:

[0031] a=(f 2 *tanβ) / (fd)

[0032]

[0033] Among them, the one with the larger absolute value of Fno1 or Fno2 is selected as Fno.

[0034] In one embodiment of the present invention, the image formed by the micro-spot array of each exposure covers the entire surface of the photosensitive material.

[0035] The present invention also proposes an image exposure system for a 3D printing device, comprising: a silicon-based liquid crystal panel, comprising a mirror electrode array, a common electrode, a liquid crystal located between the mirror electrode array and the common electrode, a first alignment film located between the mirror electrode array and the liquid crystal, and a second alignment film located between the liquid crystal and the common electrode, wherein the alignment film is raised at each mirror electrode corresponding to the mirror electrode array to form a focusing lens, and each focusing lens can converge the light irradiated to the corresponding mirror electrode, so that the micro-spot size reflected by 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 polarization direction of the light reflected by the mirror electrode array; a light source, generating a light source that irradiates the silicon-based liquid crystal panel. light; a polarized light 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, arranged in the exit direction of the polarized light splitter, so that the micro-spot array composed of the micro-spots reflected by each mirror electrode is projected onto the surface of the photosensitive material; a deflection lens, 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 where the micro-spot array is projected onto the surface of the photosensitive material; and a controller, commanding the light source to perform multiple exposures, and commanding the deflection lens to move during each exposure to project the micro-spot array of each exposure onto different positions on the surface of the photosensitive material.

[0036] The present invention also proposes an image exposure system for a 3D printing device, comprising: a silicon-based liquid crystal panel, comprising a mirror electrode array, a common electrode, a liquid crystal located between the mirror electrode array and the common electrode, a first alignment film located between the mirror electrode array and the liquid crystal, and a second alignment film located between the liquid crystal and the common electrode, each mirror electrode of the mirror electrode array being a concave mirror, capable of converging the light irradiated thereon so that the size of the reflected micro-light spot 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 polarization direction of the light reflected by the mirror electrode array; a light source, generating a light irradiated onto the silicon-based liquid crystal panel; a polarized light splitter, used to convert the light The light generated by the light source is filtered into polarized light to illuminate the silicon-based liquid crystal panel, and the light with a predetermined polarization direction is filtered out from the light reflected by the mirror electrode array; the projection lens is arranged in the exit direction of the polarized light splitter, so that the micro-spot array composed of the micro-spots reflected by each mirror electrode is projected 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, and 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 where the micro-spot array is projected onto the surface of the photosensitive material; and the 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 different positions on the surface of the photosensitive material.

[0037] The present invention also proposes an image exposure system for a 3D printing device, comprising: a silicon-based liquid crystal panel, comprising a mirror electrode array, a common electrode, a liquid crystal located between the mirror electrode array and the common electrode, a first alignment film located between the mirror electrode array and the liquid crystal, a second alignment film located between the liquid crystal and the common electrode, and a focusing lens array located 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, and each focusing lens can converge the light irradiated to the corresponding mirror electrode, so that the micro-spot size reflected by 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 polarization direction of the light reflected by the mirror electrode array; a light source, generating a light beam which irradiates the silicon-based liquid crystal panel; a polarized light splitter, which is used to filter the light generated by the light source into polarized light to irradiate 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, which is arranged in the exit direction of the polarized light splitter, so that the micro-spot array is projected onto the surface of the photosensitive material; a deflection lens, which is arranged between the silicon-based liquid crystal panel 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 position where the micro-spot array is projected onto the surface of the photosensitive material; and a controller, which commands the light source to perform multiple exposures, and commands the micro-displacement drive mechanism to move during each exposure, so as to project the micro-spot array of each exposure onto different positions on the surface of the photosensitive material.

[0038] The present invention also provides a light-curing 3D printing device, comprising the image exposure system as described above.

[0039] Due to the adoption of the above technical solution, compared with the prior art, the present invention can fill the surface of the photosensitive material with exposure spots by setting a concave lens surface or a focusing lens array in the silicon-based liquid crystal panel, combining multiple exposures with the micro-displacement of the silicon-based liquid crystal, and then using different imaging information for each exposure, which can multiply the imaging resolution and thus improve the printing accuracy.

[0040] In addition, when the photocurable material is being cured, the material will shrink to a certain extent. When a large area of ​​photocurable material is photocured at the same time, a large continuous internal stress will be generated, causing the cured object to warp and deform. The present invention uses multiple exposures to cure different pixels of the photosensitive material in a time-sharing manner, thereby avoiding the simultaneous curing of a large area of ​​photocurable material and reducing the effect of the shrinkage of pixels on the surrounding pixels, thereby improving the degree of warping and deformation of the printed body. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to make the above-mentioned objects, features and advantages of the present invention more clearly understood, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein:

[0042] Figure 1 The basic structure of a photo-curing 3D printing device is shown.

[0043] Figure 2 An image exposure system of a 3D printing device according to an embodiment of the present invention is shown.

[0044] Figure 3A Show Figure 2 A structural diagram of an embodiment of a liquid crystal on silicon panel of an image exposure system is shown.

[0045] Figure 3B yes Figure 3A Schematic diagram of a pixel of a liquid crystal on silicon panel.

[0046] Figure 3C Show Figure 3A Light path diagram of a liquid crystal on silicon panel.

[0047] Figure 4A Show Figure 2 A structural diagram of another embodiment of a liquid crystal on silicon panel of an image exposure system is shown.

[0048] Figure 4B yes Figure 4A Schematic diagram of a pixel of a liquid crystal on silicon panel.

[0049] Figure 4C yes Figure 4A Schematic diagram of the concave mirror structure of the silicon-based liquid crystal panel shown.

[0050] Figure 4D Show Figure 4A Light path diagram of a liquid crystal on silicon panel.

[0051] Figure 5A Show Figure 2 A structural diagram of another embodiment of a liquid crystal on silicon panel of the image exposure system is shown.

[0052] Figure 5B Show Figure 5A Light path diagram of a liquid crystal on silicon panel.

[0053] Figure 6 The image is shown when the LCOS panel is directly projected without focusing the light.

[0054] Figure 7 The image exposure system according to the embodiment of the present invention is shown as forming an image on the surface of a photosensitive material by a single exposure.

[0055] Figure 8The image exposure system according to the embodiment of the present invention is shown as forming an image on the surface of a photosensitive material by four exposures.

[0056] Fig. 9 A schematic diagram of image extraction of an image exposure system according to an embodiment of the present invention is shown.

[0057] Fig.10 An image exposure system of a 3D printing device according to another embodiment of the present invention is shown.

[0058] Fig.11 Show Fig.10 Schematic diagram of the optical path of the image exposure system without deflection by the deflecting lens.

[0059] Fig.12 Show Fig.10 Schematic diagram of the light path deflected by the deflection lens of the image exposure system shown.

[0060] Fig.13 The image exposure system according to another embodiment of the present invention is shown as forming an image on the surface of a photosensitive material by four exposures.

[0061] Fig.14 The curve showing the relationship between the energy required for curing photosensitive resin and the light power. DETAILED DESCRIPTION

[0062] The embodiments of the present invention describe a 3D printing device and an image exposure system thereof. The image exposure system uses a liquid crystal on silicon panel as an area array image source.

[0063] Figure 2 The image exposure system of a 3D printing device according to an embodiment of the present invention is shown. Figure 2 As shown, the image exposure system 200 of this embodiment includes a light source 201, a polarized light splitting prism 202, a liquid crystal on silicon (LCOS) panel 203, a micro-displacement drive mechanism 204, a projection lens 205, and a controller (not shown). For the sake of simplicity, components not related to the present invention are not shown.

[0064] 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 photosensitive material to be cured. For example, when UV resin is selected as the photosensitive material, the light beam can be purple light to ultraviolet light, and its wavelength is below 430nm, for example, 355-410nm.

[0065] In this embodiment, a polarized light beam splitter prism 202 is arranged between the light source 201 and the LCOS panel 203. The light emitted by the light source 201 is irradiated onto the polarized light beam splitter prism 202, and the polarized light beam splitter prism 202 reflects the S polarized light in the light to the LCOS panel 203, and the P polarized light directly passes through the polarized light beam splitter prism. Finally, after the light is reflected by the LCOS panel 203, the light whose polarization direction is not changed is reflected back to the light source, and the light whose polarization direction is changed passes through the polarized light beam splitter prism 202 and the projection lens 205 and irradiates onto the photosensitive material surface 220. Here, the polarized light beam splitter prism 202 can split the incident light into two beams of vertical linear polarized light. 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 forms an angle of 90 degrees with the P light. The S polarized light is incident on the LCOS panel 203 as the incident light. The S polarized light entering the LCOS panel 203 will be twisted by a certain angle by some liquid crystal molecules, and the twisting angle is controlled by the voltage applied to the liquid crystal panel. These lights will be reflected back to the polarized light splitting prism 202 by the LCOS panel 203. The P polarized light in the reflected light directly passes through the light-emitting side of the polarized light splitting prism 202, and the S polarized light will be reflected back to the light source by the polarized light splitting prism 202. Therefore, by individually controlling the arrangement direction of the liquid crystal molecules of each liquid crystal unit, the brightness and image of the light reflected by the LCOS panel 203 can be controlled. Although a polarized light splitting prism is used here, it can be understood that the embodiments of the present invention can also use other polarized light splitters such as reflective polarizers.

[0066] The LCOS panel 203 is used as a spatial light modulator in the present invention. Figure 3A Show Figure 2 FIG. 3c shows a structural diagram of an embodiment of an LCOS panel of an image exposure system. Figure 3A Light path diagram of LCOS panel. Figure 3A , 3BAs shown, 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 a control signal. The mirror electrode array 302 includes a plurality of mirror electrodes E, each mirror electrode E corresponding to a 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 grooves, and its function is 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 strip grooves, and its function is to guide the arrangement direction of the liquid crystal molecules. The common electrode 304 is arranged opposite to the mirror electrode array 302, and the two are spaced a certain distance apart. 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 between the two will twist at a certain angle, thereby changing the polarization direction of the light passing therethrough. Different voltages can be applied to each mirror electrode E in the mirror electrode array 302, so that the twisting angles of the liquid crystal molecules on each mirror electrode E are different. The mirror electrode E itself is also a mirror surface, which can reflect the light penetrating the liquid crystal 305 and return it to its original path. Therefore, the silicon-based liquid crystal panel 203 can adjust the state of the liquid crystal 305 according to the control signal, thereby changing the polarization direction of the micro-spot M light reflected by each mirror electrode E. The micro-spots reflected by each mirror electrode E form an image-adjustable micro-spot array. 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 converged, 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 can be the size of the mirror electrode E itself.

[0067] In the embodiment of the present invention, the first alignment film 303 is convex at each mirror electrode E of the mirror electrode array to form a focusing lens. Figure 3B As shown, 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 arrangement direction of the liquid crystal will be distributed at the convexity. It should be noted that the convexity can be in the shape of strips along the direction of the grooves 303b to facilitate manufacturing. It should be noted that the size ratio of the grooves 303b to the mirror electrode E is only for illustration and does not represent the ratio in the actual product.

[0068] The above-mentioned focusing lens, in conjunction with the strictly designed illumination system described below, can focus the light irradiated thereon into a micro spot smaller than the size of the mirror electrode. Figure 3C As shown, a series of parallel light beams with a certain angle are incident on 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 light beam is 3.5°, the image height a of the micro spot formed by the reflection of the mirror electrode is:

[0069] tan(β)=(a / 2) / (f / 2); a=2*(f / 2)*tanβ=7.3μm;

[0070] That is, an image with a size of 7.3 μm appears in front of the mirror electrode E, which is about 1 / 2 of the pixel size.

[0071] Assume W is the maximum half angle of the emitted light, then:

[0072] tan(w)=((a+p) / 2) / f=((7.3+14) / 2) / 60=0.1775, W=10.065°;

[0073] The aperture value Fno is calculated as follows:

[0074] Fno = 1 / (2tan(w)) = 2.8. (The influence of the refractive index of liquid crystal, etc. is not considered)

[0075] That is, in the optical path system, the projection lens 205 only needs to use an aperture value of 2.8 to allow all light to pass through. At the same time, the focal plane of the lens is no longer located on the mirror electrode of the LCOS panel 203, but on the micro-spot array in front of the LCOS panel, so that the 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 an image is formed on the surface of the photosensitive material to form an exposure spot.

[0076] Another benefit of convergence is that after convergence, although the micro-spot area is reduced, the micro-spot brightness 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 in the same proportion. After multiple exposures, the micro-spot will fill the entire resin surface, which allows the present invention to improve the projection resolution while keeping the total exposure time required for curing basically unchanged compared to direct exposure.

[0077] 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 circular. This requires adjusting the above parameters in actual experiments to determine the final data.

[0078] Figure 4A Show Figure 2 A structural diagram of another embodiment of the LCOS panel of the image exposure system shown in FIG. Figure 4D Show Figure 4A Light path diagram of LCOS panel. Figure 4A , 4B As shown, 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 a control signal. The mirror electrode array 402 includes a plurality of mirror electrodes E, each mirror electrode E corresponding to a pixel of the LCOS panel 203. The first alignment film 403 covers the mirror electrode array 402, which is a thin film with straight strip grooves, and its function is to guide the arrangement direction of the 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 grooves, and its function is to guide the arrangement direction of the liquid crystal molecules. The common electrode 404 is arranged opposite to the mirror electrode array 402, and the two are spaced apart 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 between the two will twist at a certain angle, thereby changing the polarization direction of the light passing through them. Different voltages can be applied to each mirror electrode E in the mirror electrode array 402, so that the twisting angles of the liquid crystal molecules on each mirror electrode E are different. The mirror electrode E itself is also a mirror surface, which can reflect the light that penetrates the liquid crystal 405 and return it to its original path. Therefore, the silicon-based liquid crystal panel 203 can adjust the state of the liquid crystal 405 according to the control signal, thereby changing the polarization direction of the micro-spot M light reflected by each mirror electrode E. The micro-spots reflected by each mirror electrode E form an image-adjustable micro-spot array. As shown Figure 4B As shown, 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 converged, 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 can be the size of the mirror electrode E itself.

[0079] Continue to refer Figure 4BAs shown, 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 as a whole except for the grooves. At this time, the grooves 403a on the first alignment film 403 for controlling the arrangement direction of the liquid crystal will be distributed in the recessed parts. It should be pointed out that the size ratio of the grooves 403a to the mirror electrode E is only for illustration and does not represent the ratio in the actual product.

[0080] In one embodiment, the mirror electrode E having a concave mirror can be formed by MEMS (micro-electromechanical system) layer by layer processing and ion polishing. Figure 4C As shown, a metal layer with a depression is fabricated layer by layer on the mirror electrode E, thereby forming a concave mirror.

[0081] 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 illumination system, the light irradiated thereon can be focused into a micro light spot smaller than the size of the mirror electrode. Figure 4D As shown in the figure, a series of parallel light beams with a certain angle are incident on a mirror electrode E with concave mirror characteristics. Assuming that the focal length f of the concave mirror electrode E is 60μm, the pixel size p corresponding to the mirror electrode E is 14μm, and the maximum half angle β of the parallel light beam is 3.5°, the image height a of the micro spot formed by the reflection of the mirror electrode is:

[0082] tan(β)=(a / 2) / f; a=2*f*tanβ=7.3μm;

[0083] That is, an image with a size of 7.3 μm appears in front of the mirror electrode E, which is about 1 / 2 of the pixel size.

[0084] Assume W is the maximum half angle of the emitted light, then:

[0085] tan(w)=((a+p) / 2) / f=((7.3+14) / 2) / 60=0.1775, W=10.065°;

[0086] The aperture value Fno is calculated as follows:

[0087] Fno = 1 / (2tan(w)) = 2.8.

[0088] That is, in the optical path system, the projection lens 205 only needs to use an aperture value of 2.8 to allow all light to pass through. At the same time, the focal plane of the lens is no longer located on the mirror electrode of the LCOS panel 203, but on the micro-spot array in front of the LCOS panel, so that the 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 an image is formed on the surface of the photosensitive material to form an exposure spot.

[0089] Another benefit of convergence is that after convergence, although the area of ​​the micro-spot is reduced, the brightness of the micro-spot is increased in the same proportion. In this way, 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 in the same proportion. After multiple exposures, the micro-spot will fill the entire resin surface. At this time, while the present invention improves the projection resolution, the total exposure time and direct exposure required for curing remain basically unchanged.

[0090] In fact, due to 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 circular. This requires adjusting the above parameters in actual experiments to determine the final data.

[0091] Figure 5A Show Figure 2 A structural diagram of another embodiment of the LCOS panel of the image exposure system shown in FIG. Figure 5B Show Figure 5A The optical path diagram of the LCOS panel (expanded from the mirror electrode reflection interface to the direct optical path diagram). Figure 5A , 5BAs shown, 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 a control signal. The mirror electrode array 502 includes a plurality of mirror electrodes E, each mirror electrode E corresponding to a 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 grooves, and its function is to guide the arrangement direction of the 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 grooves, and its function is to guide the arrangement direction of the liquid crystal molecules. The common electrode 504 is arranged opposite to the mirror electrode array 502, and the two are spaced a certain distance apart. 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 between the two will twist at a certain angle, thereby changing the polarization direction of the light passing therethrough. Different voltages can be applied to each mirror electrode E in the mirror electrode array 502, so that the twisting angles of the liquid crystal molecules on each mirror electrode E are different. The mirror electrode E itself is also a mirror surface, which can reflect the light penetrating the liquid crystal 505 and return it to its original path. Here, the reflective surface of the mirror electrode E can be a plane. Therefore, the silicon-based liquid crystal panel 203 can adjust the state of the liquid crystal 505 according to the control signal, thereby changing the polarization direction of the micro-spot M light reflected by each mirror electrode E. The micro-spots reflected by each mirror electrode E form a micro-spot array with adjustable pattern. In this embodiment, a focusing lens array 508 is provided on the incident side of the common electrode 504, and each focusing lens 508a of the focusing lens array 508 corresponds to each mirror electrode E of the mirror electrode array 402, and each focusing lens 508a can converge the light beam irradiated to the corresponding mirror electrode E, so that the size s of the micro-spot M reflected by the mirror electrode E is smaller than the pixel size p 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.

[0092] Different from the previous embodiment, in this embodiment, the first alignment film 503 and the second alignment film 506 are flat as a whole except for the grooves, and do not need to be constructed to have a focusing effect.

[0093] In the embodiment of the present invention, the focusing effect of the focusing lens array 508 of the LCOS panel, in conjunction with the strictly designed illumination system described below, can focus the light irradiated thereon into a micro light spot smaller than the size of the mirror electrode. Figure 5BAs shown in FIG. 1 (with the mirror electrode reflection interface expanded as a direct light path diagram), a parallel light beam with a certain angle passes through a focusing lens 508a, is incident on the mirror electrode E, is reflected, and passes through the focusing lens 508a again before being emitted. Figure 5B There are two lenses in the image, which are called the first lens (on the left side in the figure) and the second lens (on the right side in the figure).

[0094] Assume that the focal length of lens 508a is f, the diameter is 2p, p is the 1 / 2 pixel size corresponding to the mirror electrode, the distance from lens 508a to mirror electrode E is d, and the incident light angle is β.

[0095] M is the micro spot image passing through the first lens, and the image height is h1.

[0096] h1=f·tanβ

[0097] Consider the light P1→P2→P3→P4, P2 / P3 are the intersection points of the light and the two lenses, k i is the slope of each segment relative to the horizontal plane, y i P i The corresponding height (height of the intersection), here i = 1, 2, 3, 4. So we have:

[0098] k1=tanβ

[0099]

[0100] y2=-p

[0101]

[0102] There are several special cases:

[0103] (1) d>f. Obviously, the light cone converges and then is sent out, and the aperture at the second lens position will be greater than 2p. Adjacent pixels interfere with each other. This possibility does not exist (no practical value).

[0104] (2) 2d = f

[0105] At this time, y3=2d·tanβ

[0106]

[0107] Calculation of lens Fno1:

[0108] Fno1=1 / 2k3

[0109] M is imaged by the second lens, and the image height is set to h2. For the second lens, the object distance l=f-2d (as in the above figure, l<0).

[0110] According to the Gaussian imaging formula:

[0111]

[0112] Calculate the magnification α:

[0113]

[0114] Spot diameter:

[0115]

[0116] Then trace another ray Q1→Q2→Q3→Q4, k' i is the slope of each segment, y' i Q i The corresponding height (intersection height), i=1,2,3,4.

[0117] k′1=tanβ

[0118]

[0119] y′2=b

[0120]

[0121] The lens Fno1 is:

[0122] Fno1=1 / 2k'3

[0123] The Fno2 here is compared with the Fno1 calculated from P1→P4 above, and the smaller absolute value should be taken as the Fno of the rear projection lens.

[0124] According to the above calculation results, assuming that the focal length f of the focusing lens 508a is 100 μm, the pixel size 2p corresponding to the focusing lens 508a is 14 μm, the half angle β of the light beam is 2.5°, and the distance d between the focusing lens and the reflective electrode is 40 μm, where f must be greater than d, then the image height a of the micro spot formed by the focusing lens 508a is:

[0125] a=(f 2 *tanβ) / (fd)=7.28μm

[0126] 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 aperture value Fno is calculated as follows:

[0127]

[0128] Select Fno1 as the system Fno.

[0129] Another benefit of convergence is that after convergence, although the area of ​​the micro-spot is reduced, the brightness of the micro-spot is increased in the same proportion. In this way, 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 in the same proportion. After multiple exposures, the micro-spot will fill the entire resin surface. At this time, while the present invention improves the projection resolution, the total exposure time and direct exposure required for curing remain basically unchanged.

[0130] In fact, due to possible manufacturing defects of the focusing lens 508a, 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 circular, which requires adjusting the above parameters in actual experiments to determine the final data.

[0131] Figure 6 The image formed on the surface of the photosensitive material by the image exposure system of the embodiment of the present invention is shown. For comparison, if the light is directly imaged through the mirror electrode (the reflective surface is a plane), the image obtained will almost occupy the entire projection area (see FIG. Figure 6 ).Compare Figure 6 and Figure 7 It can be seen that after being converged by the mirror electrode or focusing lens in the form of a concave mirror, the size of the micro spot in the image is reduced. By accurately 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 is 1:4.

[0132] In addition, the ratio of the imaging spot size to the pixel size can be about 1:3 or 1:4. The reason for taking an integer multiple here is that it is necessary to insert a new micro spot in the blank part of each micro spot during subsequent micro displacement.

[0133] like Figure 7 As shown, in the image of one exposure on the surface of the photosensitive material, there are blanks between the light spots. For this reason, these blanks are filled by multiple exposures so that the light spots cover the entire surface of the photosensitive material.

[0134] like Figure 2As shown, the LCOS panel 203 is connected to a micro-displacement driving mechanism 204. The micro-displacement driving mechanism 204 can drive the LCOS panel 203 to move in the x-direction and the y-direction to fine-tune the position of the micro-spot array projected onto the surface of the photosensitive material. Here, the x and y directions are in the same plane, and this plane is perpendicular to the optical axis z of the image exposure system. When the micro-displacement driving mechanism does not drive the LCOS panel 203 to displace, the micro-spot array of the LCOS panel 203 is imaged at a first position on the surface of the photosensitive material; when the micro-displacement driving mechanism 204 drives the LCOS panel 203 to micro-displace in one direction (x or y direction), the entire micro-spot array of the LCOS panel 203 will be slightly displaced along with the LCOS panel 203, thereby imaging at a position other than the first position on the surface 220 of the photosensitive material.

[0135] The above displacement can be combined with multiple exposures to overlap the light spot images of each exposure, so that the light spots cover the surface of the photosensitive material. Specifically, the light source 201 can be exposed multiple times, and during each exposure, the LCOS panel 203 is commanded to shift to project the micro-spot array of each exposure to different positions on the surface of the photosensitive material. Figure 8 The image exposure system of the embodiment of the present invention is shown as follows: an image formed on the surface of a photosensitive material by four exposures. Figure 8 As shown, during the first exposure, a projection image A is formed; during the second exposure, since the micro-displacement driving mechanism 204 moves a distance of 1 / 2 pixel along the x direction, the micro-spot array moves slightly along the horizontal direction in the figure, and is projected into the blank between two columns of micro-spots, forming a projection image B; during the third exposure, the micro-displacement driving mechanism 204 moves along the y direction, so that the micro-spot array moves slightly along the vertical direction in the figure by a distance of 1 / 2 pixel, and is projected into the blank between two rows of micro-spots, forming a projection image C; similarly, a projection image D is formed. The projection image D has covered the entire surface of the photosensitive material.

[0136] The micro-displacement drive mechanism 204 may be a piezoelectric ceramic. 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 command the micro-displacement drive mechanism 204 to cooperate in moving in the x and y directions during each exposure.

[0137] 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.

[0138] It should be pointed out that although the superposition of the micro-spot arrays of each exposure covers the entire surface 220 of the photosensitive material, the positions of the micro-spot arrays of each exposure on the surface of the photosensitive material may be substantially non-overlapping. This is achieved by controlling the ratio of the pixel size to the spot size to be an integer, and the displacement step is just the spot size. This substantially non-overlapping setting can avoid a decrease in resolution. It can be understood that, considering factors such as the light diffraction effect, a slight overlap helps to compensate for the lack of non-rectangular edge portions of the micro-spots. Therefore, it is not required that the micro-spots do not overlap at all. In addition, although the superposition of the micro-spot array covers the entire surface of the photosensitive material, it can be understood that not every position in the micro-spot array is a bright spot through image control, but may have a dark spot.

[0139] In an embodiment of the present invention, each exposure micro-spot array contains different image information. Figure 8 For example, in the projection pattern D, the four micro-spots D1 in the virtual frame contain different image information. This means that the resolution of the projection pattern is correspondingly quadrupled. Therefore, the accuracy of 3D printing is significantly improved. These different image information can come from four different image files that can form a complete image, or they can be four sub-images extracted from an image in the same image file after processing. Fig. 9 For example, the image contains 4*4=16 pixels A1-A4, B1-B4, C1-C4, and D1-D4. Shaded pixels need to be exposed, while unshaded pixels do not need to be exposed. Here, pixel groups {A1, A3, C1, C3}, {A2, A4, C2, C4}, {B1, B3, D1, D3}, and {B2, B4, D2, D4} can be extracted from the image and used as 4 sub-images for 4 exposures. In contrast, the size of each pixel of the image used by traditional printing devices is at least Fig. 9 The 4 pixels shown are {A1, A2, B1, B2}, so the resolution is significantly lower.

[0140] In addition, experiments have shown that this method of curing different pixels of photosensitive materials in different time periods through multiple exposures has other advantages. Specifically, when photocurable materials are cured, the materials will shrink to a certain extent. When a large area of ​​photocurable materials is cured at the same time, a large continuous internal stress will be generated, causing the cured object to warp and deform. The method of the above embodiment of the present invention can reduce the effect of the shrinkage of pixels on the surrounding pixels when they are cured by allowing different pixels to cure at different times, thereby improving the degree of warping and deformation of the cured object. Figure 8As shown, a plurality of pixel points arranged at intervals on the photosensitive material are first exposed and cured to form a projection image A. When each pixel point is cured and shrunk, the surrounding areas that are pulled are still liquid photosensitive materials. The volatility of the liquid material offsets the effect of pulling and avoids the accumulation of internal stress; then, a second exposure and curing is performed to form a projection image B. The pixels (even columns) cured this time are still liquid photosensitive materials around the upper and lower directions. Therefore, the volatility of the liquid material in these two directions offsets the effect of pulling; then a third exposure and curing is performed to form a projection image C. The pixels (even rows) cured this time are still liquid photosensitive materials around the left direction. Therefore, the volatility of the liquid material in this direction offsets the effect of pulling; finally, a fourth exposure and curing is performed to form a projection image D. Only the pixels cured this time are surrounded by solid photosensitive materials. 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 the Gaussian curve, and the middle is brighter than the surrounding. In this way, when curing occurs, the middle of the pixel will cure faster than the edge, and the internal stress during the curing in the middle can also be partially absorbed by the surrounding uncured resin. When it is fully cured, the accumulated internal stress is very small. More importantly, because only the separated pixels are curing at the same time, and the adjacent pixels will not be cured at the same time, it avoids the pulling of each pixel when curing at the same time.

[0141] In a preferred embodiment, reference Fig.13 As shown in the figure, after the first exposure and curing is performed to form the projection image A, the second exposure and curing is performed to form the projection image B. The pixel points cured in the projection image B are located at the diagonal of the pixel points cured in the projection image A and are not adjacent to each other. Therefore, the pixels cured this time are still liquid photosensitive materials in the four directions around them. The volatility of the liquid material offsets the effect of pulling. Then the third exposure and curing are performed to form the projection image C and the fourth exposure and curing are performed to form the projection image D. Fig.10 The embodiments shown are the same and will not be expanded here.

[0142] Similarly, when performing 9 exposures or 16 exposures, several projection images whose pixels are not adjacent to each other may be exposed first to minimize the influence of mutual pulling.

[0143] In the above example, when the micro spot size is controlled to be 1 / 2 of the pixel size, 4 exposures are performed. It can be understood that when the micro spot size is controlled to be 1 / 3 of the pixel size, 9 exposures can be performed, when the micro spot size is controlled to be 1 / 4 of the pixel size, 16 exposures can be performed, and so on.

[0144] Fig.10An image exposure system of a 3D printing device according to another embodiment of the present invention is shown. In the image exposure system 200' of this embodiment, a deflection lens 206 is used to replace the aforementioned micro-displacement drive mechanism 204. The deflection lens 206 can be arranged at any position in the optical path from the LCOS panel 203 to the photosensitive material surface 220, and is generally arranged near the projection lens 205. The deflection lens 206 can be deflected around at least one rotation axis to fine-tune the position where the light beam is projected onto the surface of the photosensitive material. The aforementioned rotation axes are perpendicular to the optical axis z of the image exposure system. When the deflection lens 206 is parallel to the LCOS panel 203 (perpendicular to the optical axis z), the light is irradiated vertically onto the deflection lens 206 (such as Fig.11 As shown in FIG. 2 ), no refraction occurs at this time, and the light directly passes through the deflecting lens 206; if the deflecting lens 206 is tilted at an angle around a rotation axis, the light will be refracted when it enters the deflecting lens 206 from the air, and will be refracted again when it enters the air from the deflecting lens 206. The refraction angles of the two refractions are the same, but the directions are opposite. The refracted light will move in the original direction, but will be slightly displaced (such as Fig.12 In addition, the rotation axis may be a rotation axis y 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 capable of deflecting around the rotation axis x and around the rotation axis y. The number of the deflection lenses 206 may be one, or two or more.

[0145] Similarly, the above deflection can be combined with multiple exposures to overlap the light beam images of each exposure so that the light spot covers the surface of the photosensitive material. Specifically, the light source 201 can be exposed multiple times, and during each exposure, the deflection lens 206 is commanded to deflect so as to project the light beam images of each exposure to different positions on the surface of the photosensitive material.

[0146] 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 command the deflection lens 206 to cooperate in deflection in the x and y directions during each exposure.

[0147] Next, we will explain the principle that exposure brightness is conducive to the photosensitivity of photosensitive materials. After a certain amount of light is irradiated, the photosensitive material will solidify within a certain period of time, which is called the curing time. The power of light irradiation, that is, the amount of light energy received by the photosensitive material per unit time, will significantly affect the curing time. In theory, the energy required for curing a certain area of ​​photosensitive material can be expressed as:

[0148] W=P*t, P is the light power irradiated on the resin, and t is the exposure time.

[0149] That is, the same energy can be used to achieve the same curing effect by increasing the light power and reducing the exposure time, or by increasing the exposure time with a lower light power. This is called the "reciprocity law." However, there are cases where the reciprocity law is distorted in photosensitive resins.

[0150] Fig.14 The relationship between the energy required for curing photosensitive resin and the light power is shown in the figure. Fig.14 As shown, the x-axis represents the illumination power, and the y-axis represents the energy W required for curing. The curve represents the energy required for curing of a certain area of ​​photosensitive material under different illumination powers. When the illumination power is below P0, the required energy W is infinite, and since t=W / P, it requires infinite time. 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 segment, as the illumination power increases, the required curing time is inversely proportional to the illumination power, and the energy required for curing remains basically unchanged, which basically conforms to the above-mentioned "reciprocity law"; in the nonlinear segment, as the illumination power decreases, the required curing time increases nonlinearly and rapidly, and the energy required for curing increases nonlinearly. In the area close to P0, a slight decrease in illumination power requires a large increase in exposure time to cure the resin to the same degree. Since the wavelength of light required for photosensitive resin is below 430nm, excessive 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 of the original size, the brightness is 4 times the original size, so that the exposure enters a relatively linear section, 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, thereby extending the life of the liquid crystal panel.

[0151] In some embodiments, the controller of the image exposure system 200 and 200' may include one or more hardware processors, such as a microcontroller, a microprocessor, a reduced instruction set computer (RISC), an application-specific integrated circuit (ASIC), an application-specific instruction integrated processor (ASIP), a central processing unit (CPU), a graphics processing unit (GPU), a physical processing unit (PPU), a microcontroller unit, a digital signal processor (DSP), a field programmable gate array (FPGA), an advanced RISC machine (ARM), a programmable logic device (PLD), any circuit or processor capable of performing one or more functions, etc. For example, the controller includes a processor that loads and executes computer instructions in a memory to implement the control steps of the embodiments of the present invention.

[0152] The above-mentioned embodiment of the present invention realizes focusing by setting the mirror electrode of the LCOS panel as a concave mirror or adding a focusing lens. By combining multiple exposures with the micro-displacement of the LCOS panel, the surface of the photosensitive material can be filled with exposure spots. Different imaging information is then used for each exposure, which can improve the resolution of the imaging and thus improve the printing accuracy.

[0153] Although the present invention has been described with reference to the current specific embodiments, a person skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and various equivalent changes or substitutions may be made without departing from the spirit of the present invention. Therefore, any changes or modifications to the above embodiments within the spirit of the present invention will fall within the scope of the claims of this application.

Claims

1. An image exposure system for a 3D printing device, comprising: A liquid crystal on silicon panel, comprising a mirror electrode array, a common electrode, a liquid crystal located between the mirror electrode array and the common electrode, a first alignment film located between the mirror electrode array and the liquid crystal, and a second alignment film located between the liquid crystal and the common electrode, wherein the first alignment film is raised at each mirror electrode corresponding to the mirror electrode array to form a focusing lens, and each focusing lens can converge the light irradiated to the corresponding mirror electrode, so that the micro-spot size reflected by 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 a control signal, so as to change the polarization direction of each light reflected by the mirror electrode array; A light source, generating a light beam to illuminate the liquid crystal on silicon panel; A polarized light 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 with a predetermined polarization direction from the light reflected by the mirror electrode array; A projection lens is arranged in the outgoing direction of the polarized light 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 driving mechanism, connected to the LCOS panel, capable of driving the LCOS panel to move in a first direction and a second direction perpendicular to each other, so as to fine-tune the position where the micro-spot array is projected onto the surface of the photosensitive material; as well as The controller commands the light source to perform multiple exposures, and commands the micro-displacement drive mechanism to move during each exposure, so as to project the micro-spot arrays of each exposure to different positions on the surface of the photosensitive material.

2. The image exposure system of the 3D printing device according to claim 1, characterized in that: The images formed by the micro-spot arrays of each exposure on the surface of the photosensitive material do not overlap with each other.

3. The image exposure system of the 3D printing device according to claim 1, characterized in that: The image formed by the micro-spot array of each exposure covers the surface of the photosensitive material.

4. The image exposure system of the 3D printing device according to claim 1, characterized in that: The micro-spot array of each exposure contains different image information.

5. The image exposure system of the 3D printing device according to claim 1, characterized in that: Assuming 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, the image height of the micro spot is a, and the maximum half angle of the emitted light is W, then: tan(β)=(a / 2) / (f / 2); tan(w)=((a+p) / 2) / (f / 2); Fno = 1 / (2tan(w)).

6. The image exposure system of the 3D printing device according to claim 1, characterized in that: The ratio of the size of the micro light spot to the pixel area corresponding to the mirror electrode is approximately 1:4, 1:9 or 1:

16.

7. The image exposure system of the 3D printing device according to claim 6, characterized in that: The exposure times of the light source are 4, 9 or 16 times.

8. An image exposure system for a 3D printing device, comprising: A liquid crystal on silicon panel, comprising a mirror electrode array, a common electrode, a liquid crystal located between the mirror electrode array and the common electrode, a first alignment film located between the mirror electrode array and the liquid crystal, and a second alignment film located between the liquid crystal and the common electrode, wherein each mirror electrode of the mirror electrode array is a concave mirror capable of converging the light irradiated thereon so that the size of the reflected micro-light 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 a control signal, thereby changing the polarization direction of each light reflected by the mirror electrode array; A light source, generating a light beam to illuminate the liquid crystal on silicon panel; A polarized light 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 with a predetermined polarization direction from the light reflected by the mirror electrode array; A projection lens is arranged in the outgoing direction of the polarized light 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 driving mechanism, connected to the LCOS panel, capable of driving the LCOS panel to move in a first direction and a second direction perpendicular to each other, so as to fine-tune the position where the micro-spot array is projected onto the surface of the photosensitive material; as well as The controller commands the light source to perform multiple exposures, and commands the micro-displacement drive mechanism to move during each exposure, so as to project the micro-spot arrays of each exposure to different positions on the surface of the photosensitive material.

9. The image exposure system of the 3D printing device according to claim 8, characterized in that: The images formed by the micro-spot arrays of each exposure on the surface of the photosensitive material do not overlap with each other.

10. The image exposure system of the 3D printing device according to claim 8, characterized in that: The image formed by the micro-spot array of each exposure covers the surface of the photosensitive material.

11. The image exposure system of the 3D printing device according to claim 8, characterized in that: The size of the micro light spot is smaller than, equal to or larger than half of the pixel size corresponding to the mirror electrode.

12. The image exposure system of the 3D printing device according to claim 8, characterized in that: Assuming 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, the image height of the micro spot is a, and the maximum half angle of the emitted light is W, then: tan(β)=(a / 2) / f; tan(w)=((a+p) / 2) / f; Fno = 1 / (2tan(w)).

13. The image exposure system of the 3D printing device according to claim 8, characterized in that: The micro-spot array of each exposure contains different image information.

14. The image exposure system of the 3D printing device according to claim 8, characterized in that: The ratio of the size of the micro light spot to the pixel area corresponding to the mirror electrode is 1:4, 1:9 or 1:

16.

15. The image exposure system of the 3D printing device according to claim 14, characterized in that: The exposure times of the light source are 4, 9 or 16 times.

16. The image exposure system of the 3D printing device according to claim 8, characterized in that: The first alignment film is correspondingly recessed at each mirror electrode concave mirror of the mirror electrode array.

17. An image exposure system for a 3D printing device, comprising: A liquid crystal on silicon panel, comprising a mirror electrode array, a common electrode, a liquid crystal located between the mirror electrode array and the common electrode, a first alignment film located between the mirror electrode array and the liquid crystal, a second alignment film located between the liquid crystal and the common electrode, and a focusing lens array located on the incident side of the common electrode, wherein each focusing lens of the focusing lens array corresponds to each mirror electrode of the mirror electrode array, and each focusing lens can converge the light irradiated to the corresponding mirror electrode, so that the micro-spot size reflected by 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 a control signal, so as to change the polarization direction of the light reflected by the mirror electrode array; A light source, generating a light beam to illuminate the liquid crystal on silicon panel; A polarized light 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 with a predetermined polarization direction from the light reflected by the mirror electrode array; A projection lens is arranged in the outgoing direction of the polarized light splitter to project the micro-spot array onto the surface of the photosensitive material; A micro-displacement driving mechanism, connected to the LCOS panel, capable of driving the LCOS panel to move in a first direction and a second direction perpendicular to each other, so as to fine-tune the position where the micro-spot array is projected onto the surface of the photosensitive material; as well as The controller commands the light source to perform multiple exposures, and commands the micro-displacement drive mechanism to move during each exposure, so as to project the micro-spot arrays of each exposure to different positions on the surface of the photosensitive material.

18. The image exposure system of the 3D printing device according to claim 17, characterized in that: The images formed by the micro-spot arrays of each exposure on the surface of the photosensitive material do not completely overlap with each other.

19. The image exposure system of the 3D printing device according to claim 17, characterized in that: The image formed by the micro-spot array of each exposure covers the surface of the photosensitive material.

20. The image exposure system of the 3D printing device according to claim 17, characterized in that: The micro-spot array of each exposure contains different image information.

21. The image exposure system of the 3D printing device according to claim 17, characterized in that: Assuming 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, the half angle of the light incident on each micromirror is β, the image height of the micro spot is a, f>d, then: a=(f 2 *tanβ) / (f-d) Among them, the one with the larger absolute value of Fno1 or Fno2 is selected as Fno.

22. The image exposure system of the 3D printing device according to claim 17, characterized in that: The size of the micro light spot is smaller than, equal to or larger than half of the pixel size corresponding to the mirror electrode.

23. The image exposure system of the 3D printing device according to claim 17, characterized in that: The ratio of the size of the micro light spot to the pixel area corresponding to the mirror electrode is 1:4, 1:9 or 1:

16.

24. The image exposure system of the 3D printing device according to claim 23, characterized in that: The exposure times of the light source are 4, 9 or 16 times.

25. An image exposure system for a 3D printing device, comprising: A liquid crystal on silicon panel, comprising a mirror electrode array, a common electrode, a liquid crystal located between the mirror electrode array and the common electrode, a first alignment film located between the mirror electrode array and the liquid crystal, and a second alignment film located between the liquid crystal and the common electrode, wherein the alignment film is raised at each mirror electrode corresponding to the mirror electrode array to form a focusing lens, and each focusing lens can converge the light irradiated to the corresponding mirror electrode, so that the micro-spot size reflected by 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 a control signal, so as to change the polarization direction of the light reflected by the mirror electrode array; A light source, generating a light beam to illuminate the liquid crystal on silicon panel; A polarized light 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 with a predetermined polarization direction from the light reflected by the mirror electrode array; A projection lens is arranged in the outgoing direction of the polarized light 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 LCOS panel 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 position of the micro-spot array projected onto the surface of the photosensitive material; as well as The controller commands the light source to perform multiple exposures, and commands the deflection lens to move during each exposure, so as to project the micro-spot array of each exposure onto different positions on the surface of the photosensitive material.

26. An image exposure system for a 3D printing device, comprising: A liquid crystal on silicon panel, comprising a mirror electrode array, a common electrode, a liquid crystal located between the mirror electrode array and the common electrode, a first alignment film located between the mirror electrode array and the liquid crystal, and a second alignment film located between the liquid crystal and the common electrode, wherein each mirror electrode of the mirror electrode array is a concave mirror capable of converging light irradiated thereon so that the size of the reflected micro-light 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 a control signal, thereby changing the polarization direction of the light reflected by the mirror electrode array; A light source, generating a light beam to illuminate the liquid crystal on silicon panel; A polarized light 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 with a predetermined polarization direction from the light reflected by the mirror electrode array; A projection lens is arranged in the outgoing direction of the polarized light 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 LCOS panel 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 position of the micro-spot array projected onto the surface of the photosensitive material; as well as The controller commands the light source to perform multiple exposures, and commands the deflection lens to move during each exposure, so as to project the micro-spot array of each exposure onto different positions on the surface of the photosensitive material.

27. An image exposure system for a 3D printing device, comprising: A liquid crystal on silicon panel, comprising a mirror electrode array, a common electrode, a liquid crystal located between the mirror electrode array and the common electrode, a first alignment film located between the mirror electrode array and the liquid crystal, a second alignment film located between the liquid crystal and the common electrode, and a focusing lens array located on the incident side of the common electrode, wherein each focusing lens of the focusing lens array corresponds to each mirror electrode of the mirror electrode array, and each focusing lens can converge light irradiated to the corresponding mirror electrode, so that the micro-spot size reflected by 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 a control signal, so as to change the polarization direction of the light reflected by the mirror electrode array; A light source, generating a light beam to illuminate the liquid crystal on silicon panel; A polarized light 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 with a predetermined polarization direction from the light reflected by the mirror electrode array; A projection lens is arranged in the outgoing direction of the polarized light splitter to project the micro-spot array onto the surface of the photosensitive material; A deflection lens is arranged between the LCOS panel 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 position of the micro-spot array projected onto the surface of the photosensitive material; as well as The controller commands the light source to perform multiple exposures, and commands the deflection lens to move during each exposure, so as to project the micro-spot array of each exposure onto different positions on the surface of the photosensitive material.

28. A light-curing 3D printing device, comprising the image exposure system according to any one of claims 1 to 27.

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