Photocuring 3D printer and imaging device thereof

Abstract

The utility model discloses a photocuring 3D printer and an imaging device thereof, and the imaging device comprises a mounting bracket, and a light source device, a Fresnel lens, a display screen and a lens group which are sequentially arranged on the mounting bracket from top to bottom, the Fresnel lens is located between the light source device and the display screen and used for collecting light rays emitted by the light source device, and the collected light rays penetrate through a light-transmitting area of the display screen and are imaged through the lens set. According to the technical scheme of the utility model, the problem that a liquid crystal display screen is easy to damage in the prior art can be solved, and the problems of high cost of a lens group and large size of an imaging device in the scheme of adopting the lens group are further solved; and the problems of optical distortion and scattering caused by the fact that the Fresnel lens is directly located in the imaging path of the display screen and the lens group in the related design can be effectively avoided, so that the imaging quality is optimized, and the curing precision and quality in the printing process are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of 3D printing, in particular to a light-curing 3D printer and an imaging device thereof. Background Art

[0002] At present, most of the light-curing 3D printers on the market use lamination imaging technology. The LCD screen emits UV light in the shape of a cross-sectional image to irradiate the liquid surface of the photosensitive resin and solidify it according to the shape of the cross-sectional image, thereby realizing the 3D printing process of layer-by-layer solidification. However, since the LCD screen cannot project light from a long distance, it can only be tightly attached to the bottom of the material tray for bottom projection display molding. However, the printing speed is very slow, not only does it need to be peeled off slowly, but the LCD screen is easily crushed, which seriously shortens the service life of the LCD screen;

[0003] In the related art, a lens group is used to project the cross-sectional image of the LCD screen onto the material trough in proportion to solve the above problem. However, there is a problem of insufficient clarity in the projection imaging process, which leads to insufficient smoothness and detail on the surface of the printed object during the 3D printing process.

[0004] The above contents are only used to assist in understanding the concept of the present invention and do not constitute an admission that the above contents are related technologies. Utility Model Content

[0005] The main purpose of the utility model is to provide an imaging device, aiming to solve the problem of easy damage of liquid crystal display screens in related technologies, and further solve the problem of high cost of lens groups and large size of imaging devices in the solution using lens groups; at the same time, the imaging quality of the projection is optimized and the curing accuracy and quality during the printing process are improved.

[0006] To achieve the above-mentioned purpose, the utility model proposes an imaging device for a light-curing 3D printer, comprising:

[0007] Mounting bracket; and

[0008] The Fresnel lens is located between the light source device and the display screen, and is used to collect the light emitted by the light source device. The collected light passes through the light-transmitting area of ​​the display screen and is imaged by the lens group.

[0009] The technical solution of the utility model adopts a mounting bracket, a light source device, a Fresnel lens, a display screen and a lens group arranged on the mounting bracket from top to bottom in sequence; the mounting bracket is adapted to form an optical path layout, the display screen forms a light-transmitting area matching the cross-sectional image required for printing after receiving a control signal, the Fresnel lens converges the light of the light source device and projects it onto the display screen, and the light passing through the light-transmitting area projects the cross-sectional image formed by the light-transmitting area out of the lens group in proportion. The cross-sectional image of the display screen is projected in proportion by the lens group, thereby solving the problem in the related art that the LCD screen needs to be attached to the bottom of the material tray for bottom projection display molding, the LCD screen is easily crushed, the service life of the LCD screen is seriously shortened, and the printing speed is very slow. Placing the Fresnel lens between the light source device and the display screen can reduce the size of the lens group, reduce costs and facilitate miniaturization of the equipment; and compared with the solution in which the Fresnel lens is arranged between the lens group and the display screen, the Fresnel lens is directly located in the imaging path of the display screen and the lens group, directly inheriting the idea of ​​projector technology, and not fully considering the strict requirements of 3D printing for precision; because the design of the Fresnel lens contains many small concave and convex surfaces or "edges and corners", subtle textures or unevenness appear during the imaging process, affecting the smoothness and detail of the surface of the printed object. The present application reconfigures the position of the Fresnel lens, and the Fresnel lens is located between the light source device and the display screen, effectively avoiding the optical distortion and scattering problems caused by the Fresnel lens being directly located in the imaging path of the display screen and the lens group in the related design. In scenarios where more refined imaging is required, the subtle textures or unevenness in the image contour are optimized, thereby optimizing the imaging quality and improving the curing accuracy and quality during the printing process.

[0010] Optionally, the Fresnel lens is in close contact with the display screen.

[0011] Optionally, a UV adhesive layer is formed between the Fresnel lens and the display screen, and the Fresnel lens and the display screen are bonded and fixed by the UV adhesive layer.

[0012] Optionally, in the horizontal projection direction, the projection area of ​​the lens group is smaller than the projection area of ​​the Fresnel lens.

[0013] Optionally, in the horizontal projection direction, the projection area of ​​the Fresnel lens is greater than or equal to the projection area of ​​the display screen.

[0014] Optionally, the lens group is a Gaussian lens, a Tessar lens, or a Cooke three-piece lens.

[0015] Optionally, the light source device adopts a COB light source.

[0016] Optionally, the light source device includes a light source composed of a plurality of light emitting diodes arranged in an array and / or a plurality of laser diodes arranged in an array, and a focusing lens for collimating the light of the light source.

[0017] Optionally, the focal length of the lens group is adjustable.

[0018] Optionally, the Fresnel lens and the display screen are arranged in the mounting bracket, the light source device is arranged above the mounting bracket, the lens group is arranged below the mounting bracket, and a closed optical path channel is formed between the light source device, the mounting bracket and the lens group.

[0019] The utility model also provides a light-curing 3D printer, comprising:

[0020] A frame, an imaging device as described above, a material storage tank, a molding platform, and a lifting mechanism;

[0021] The imaging device, the lifting mechanism and the material storage trough are arranged on the frame, the material storage trough is arranged below the imaging device, and the material storage trough is used to place liquid photocurable material; the molding platform is fixedly connected to the lifting mechanism, and the lifting mechanism is used to drive the molding platform to extend into or move out of the material storage trough. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the utility model or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0023] Figure 1 This is a schematic structural diagram of an embodiment of an imaging device of the utility model;

[0024] Figure 2 This is a schematic structural diagram of an embodiment of a light-curing 3D printer of the utility model;

[0025] Figure 3 for Figure 2 A schematic diagram of the structure from another perspective;

[0026] Figure 4 for Figure 3 Schematic diagram of the cross-section structure in.

[0027] Description of Figure Numbers:

[0028]

[0029] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0031] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0032] In addition, the descriptions of "first", "second", etc. in the present utility model are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.

[0033] At present, most of the light-curing 3D printers on the market use lamination imaging technology. The LCD screen emits UV light in the shape of a cross-sectional image to irradiate the liquid surface of the photosensitive resin and solidify it according to the shape of the cross-sectional image, thereby realizing the 3D printing process of layer-by-layer solidification. However, since the LCD screen cannot project light from a long distance, it can only be tightly attached to the bottom of the material tray for bottom projection display molding. However, the printing speed is very slow, not only does it need to be peeled off slowly, but the LCD screen is easily crushed, which seriously shortens the service life of the LCD screen;

[0034] In the related art, in order to reduce the size of the lens group, reduce costs and facilitate miniaturization of the device, the Fresnel lens is arranged between the lens group and the display screen, but there are problems of optical distortion and scattering, which affect the accuracy of imaging. Specifically, the design of the Fresnel lens contains many small concave and convex surfaces or "edges", which helps to reduce the thickness and weight of the lens. However, these features may cause inconsistencies during the die-casting manufacturing process, thereby introducing optical distortion. This distortion may cause subtle textures or unevenness in the imaging process, affecting the smoothness and detail of the printed object surface, thereby reducing the sharpness and accuracy of the imaging, and affecting the accuracy and quality of 3D printing.

[0035] For this purpose, refer to Figure 1 , Figure 1 The present invention is a schematic diagram of the structure of an embodiment of an imaging device of the present invention. The present invention proposes an imaging device 100 including a mounting bracket 110, and a light source device 120, a Fresnel lens 150, a display screen 170 and a lens group 200 arranged on the mounting bracket 110 from top to bottom; the Fresnel lens 150 is located between the light source device 120 and the display screen 170, and is closer to the display screen 170, so as to collect the light emitted by the light source device 120 and pass it through the display screen 170, so that the imaging pattern in the display screen 170 can be projected to an external display through the lens group 200.

[0036] Reference Figure 1 In one embodiment of the present invention, the imaging device 100 is applied to a light-curing printer, referring to Figures 2 to 4 The photocuring 3D printer 100 includes a lifting mechanism, a material trough, a molding platform 300 and an imaging device 100, etc. The lifting mechanism controls the lifting and lowering of the imaging device 100, and a photosensitive material, such as liquid photosensitive resin, is placed in the material trough; the 3D photocuring printing technology currently formed on the market adopts a bonding imaging technology, and the liquid crystal display 170 emits UV light in the shape of a cross-sectional image to irradiate the liquid surface of the photosensitive resin and solidify it according to the shape of the cross-sectional image, thereby realizing the layer-by-layer curing molding 3D printing process.

[0037] Specifically, refer to Figure 3 and Figure 4The mounting bracket 110 is provided with a mounting groove, the Fresnel lens 150 and the display screen 170 are arranged in the mounting groove, the light source device 120 is arranged above the mounting groove, the lens group 200 is arranged below the mounting groove, and a closed optical path channel is formed between the light source device 120, the mounting bracket 110 and the lens group 200. The display screen 170 and the Fresnel lens 150 are arranged on the mounting bracket 110 in a close relationship, and are fixed to the lifting mechanism of the light-curing 3D printer 100 through the mounting bracket 110 to fix the imaging device 100. A light guide structure 180 is also provided on the optical path between the display screen 170 and the lens group 200, and the light passing through the display screen 170 enters the lens group 200, thereby ensuring the quality and accuracy of the image projected from the lens group 200. The light guide structure 180 can be configured as a light guide cover; or other optical structures that are conducive to the propagation of the optical path.

[0038] The working principle of the light-curing printer is to use the LCD screen imaging principle. Under the drive of the computer and the display screen 170 circuit, the computer program provides image signals, and a selective transparent area appears on the LCD screen. The ultraviolet light passes through the transparent area and irradiates the photosensitive resin consumables in the resin tank for exposure and curing. After each layer of curing time is over, the platform support plate lifts the cured part to allow the resin liquid to replenish and flow back. The platform drops again, and the thin layer between the model and the release film is exposed to ultraviolet light again. In this way, it is cured layer by layer and printed into a beautiful three-dimensional model.

[0039] However, since the LCD screen 170 uses a laminating imaging technology, it cannot project light from a long distance and can only be tightly attached to the bottom of the material tray for bottom projection display molding. However, the printing speed is very slow, and not only does it need to be slowly peeled off, but the LCD screen 170 is easily crushed, which seriously shortens the service life of the LCD screen 170.

[0040] Specifically, since the LCD screen 170 cannot project light from a long distance, the LCD screen 170 can only be close enough to the photosensitive material to ensure printing accuracy and ensure that the photosensitive material can be cured; this method also limits the LCD screen 170 to be tightly attached to the bottom of the material tray for bottom projection display molding, that is, it is necessary to adopt a pull-up 3D printing, that is, the molding platform 300 needs to pull and adjust each time a layer of molding graphics is formed to print the next layer. In this process, the situation will be much more complicated due to the emergence of release force. The release force refers to the force required when the molding platform 300 and the molded part are separated from the material storage tank. In this way, the most important element to consider becomes how to reduce the pull-out force / release force. There are many factors that affect the pull-out force / release force: resin viscosity, release speed, new molding layer area, and the height distance between the new molding layer and the release film. In addition, during this process, there are also uncleaned / fallen solidified particles, which squeeze the LCD screen 170 during the descent of the molding platform 300, or the release film on the LCD screen 170 is damaged, causing the photosensitive material to solidify on the LCD screen 170. Therefore, the LCD screen 170 is easily damaged and the printing speed is very slow.

[0041] The technical solution of the utility model adopts a light source device 120, a Fresnel lens 150, a display screen 170 and a lens group 200 which are arranged in sequence from top to bottom on the mounting bracket 110; so that the light 400 with a cross-sectional image of the liquid crystal display screen 170 can enter the lens group 200, and the lens group 200 needs to be able to display the image of the liquid crystal display screen 170 in proportion and solidify the photosensitive material, thereby solving the problem that the liquid crystal display screen 170 is easily crushed, which seriously shortens the service life of the liquid crystal display screen 170 and the printing speed is very slow.

[0042] Specifically, the technical solution of the utility model adopts upper projection and sinking printing. After the imaging device 100 generates a cross-sectional image, a photopolymerization reaction occurs in the area where the resin layer is very thin to form a thin layer of the part. Then the molding table moves down one layer, and the imaging device 100 continues to generate the next cross-sectional image and then continues to process the next layer. This cycle continues until the printing is completed. The projection light of the imaging device 100 directly irradiates the top layer of the molded part, and there is no need to separate the molded part and the material trough, which saves trouble.

[0043] The light source device 120 is used to emit light 400 that can cure photosensitive materials. In one embodiment, a UV array light source can be used to increase the energy and irradiation range of the light 400. In one embodiment, the light source 130 can also use a single UV light source. For example, the single UV light source can be combined with a light guide plate or a reflector to increase the energy and irradiation range of the light 400.

[0044] In order to further improve the efficiency and flexibility of the light source device 120, an LED light source may be used; an LED light source has the characteristics of long life, low power consumption and fast response. By integrating multiple LED lamp beads in a compact device, a high-brightness, uniformly irradiated light source can be formed, which is very suitable for curing photosensitive materials.

[0045] Furthermore, in order to reduce costs, the light source device 120 uses a COB light source, which can disperse the heat dissipation of the chip, improve the light efficiency, and improve the glare effect of the LED light. COB has a high light flux density, less glare and soft light, and emits a uniformly distributed light surface.

[0046] Specifically, the light source device 120 includes a light source 130 composed of a plurality of light emitting diodes arranged in an array and / or a plurality of laser diodes arranged in an array, and a condenser 140 for collimating the light 400 of the light source 130. The light 400 emitted by the light source has a scattering problem, that is, a phenomenon that a part of the light 400 deviates from the original propagation direction. In order to make the emitted light source project evenly and avoid the light 400 emitted by the UV array light source from crossing, the uniformity of the light power finally projected on the liquid crystal display screen 170 is not high, thereby affecting the overall printing accuracy. The condenser 140 is configured as a collimating and uniform light array lens, and the flat surface of the collimating and uniform light array lens is arranged opposite to the light source 130, so that the light 400 emitted by the light source 130 passes through the flat surface of the collimating and uniform light array lens to the concave and convex surface, and the light path propagation direction is perpendicular to the collimating and uniform light array lens, that is, the projection direction of the cross light 400 originally generated due to scattering or different emission angles is uniformly converted into vertical downward, ensuring that the light is not scattered before entering the Fresnel lens, reducing energy loss, so as to better project the cross-sectional image of the liquid crystal display screen 170, thereby improving printing accuracy.

[0047] In one embodiment, the light source device 120 is composed of a plurality of light emitting diodes arranged in an array, which are excited by current to generate light 400. In order to accurately focus the light 400, a condenser 140 may be provided as an optical element to collimate the light 400 emitted by the light emitting diodes.

[0048] In another embodiment, a plurality of laser diodes arranged in an array are used to form the light source device 120. The laser diode is a light source that can generate a high-intensity, monochromatic, coherent light beam. By adjusting the working state of the laser diode, precise control of the light beam can be achieved. In combination with the use of the condenser 140, the light 400 emitted by the laser diode can be focused on the target area to achieve precise illumination or projection.

[0049] In addition, in order to achieve more precise control of the light 400, the light source device 120 can also be equipped with an intelligent dimming system. The system can automatically adjust the brightness and irradiation time of the light source according to the type and thickness of the photosensitive material to ensure that the material is cured under optimal conditions. The intelligent dimming system can detect the reflectivity and transmittance of the material through sensors, thereby adjusting the light source parameters in real time to improve the curing quality and efficiency.

[0050] In terms of heat dissipation design of the light source device 120, active heat dissipation measures such as heat sinks and fans can be used to ensure that the light source can maintain stable performance when working at high intensity. In addition, by optimizing the structure and material selection of the light source, its heat dissipation performance can be further improved and its service life can be extended.

[0051] In this solution, the Fresnel lens 150 is arranged between the light source device 120 and the display screen 170. On the one hand, the Fresnel lens 150 is located above the LCD screen to converge the light 400, so that the light 400 passes through the screen of the display screen 170 at an angle and then enters the lens group 200, thereby ensuring the imaging quality; on the other hand, the size of the lens group 200 can be reduced, and there is no need to set the lens group 200 larger than the LCD screen 170, thereby ensuring the printing effect and reducing the cost; at the same time, the size of the printer is reduced, which is conducive to the miniaturization of the equipment.

[0052] In one embodiment, the display screen 170 may be an LCD (liquid-crystal display). In other embodiments, the display screen 170 may also be other display screens 170 capable of selective light transmission. Unlike ordinary display screens 170, the liquid crystal display screen 170 used in a light-curing printer often does not require a backlight because it uses UV LED as a light source. Light-curing printing technology uses digital surface exposure to form. The light 400 is passed through the Fresnel lens 150 to collect the light 400 and then pass through the display screen 170. Using the imaging principle of the liquid crystal display screen 170, under the drive of the microcomputer and the display screen 170 driving circuit, the computer program provides an image signal, and a selective transparent area appears on the liquid crystal screen, that is, a light-transmitting area matching the cross-sectional image required for printing. The light 400 is projected onto the liquid surface of the photosensitive resin in the material tank through the lens group 200 and solidified according to the shape of the cross-sectional image. The printed entity is finally obtained by curing the single layer image layer by layer.

[0053] Fresnel lens 150, in simple terms, has equidistant teeth on one side of the lens. Through these teeth, the light bandpass (reflection or refraction) of a specified spectral range can be achieved. Conventional optical filters made from polished optical equipment are expensive. Fresnel lens 150 can greatly reduce costs. Because these lenses are very thin, there is very little light energy lost due to absorption. Due to this unique thread design, Fresnel lens 150 can focus a wide range of incident light to a single focus.

[0054] The design of the related technology directly inherits the idea of ​​projector technology, without fully considering the strict requirements of 3D printing for accuracy. Specifically, in the early stages of technology development, many design concepts and solutions came from advanced technologies in other fields, such as projector technology. In a projector, a Fresnel lens 150 is often placed between the lens group and the LCD screen to optimize the optical path and improve image quality. This design is considered effective and practical, and thus became a reference for the design of early photocuring 3D printers. However, this industry inertia ignores the fundamental difference between 3D printing and traditional projection display: 3D printing has much higher requirements for imaging accuracy than visual viewing tolerance. The human eye can tolerate tiny pixel deviations, while any tiny errors in 3D printing may lead to product quality problems.

[0055] In this solution, the Fresnel lens 150 is placed between the light source device 120 and the display screen 170; this can effectively avoid the optical distortion and scattering problems caused by the Fresnel lens 150 being directly located in the imaging path of the display screen 170 and the lens group 200. Moving the Fresnel lens 150 from the traditional position to between the light source device 120 and the display screen 170 means that the entire optical path needs to be redesigned and optimized. New components and bracket structures need to be developed to adapt to the new optical path layout.

[0056] This solution helps reduce stray light caused by small corners of the lens because the light 400 is homogenized before forming an image through the LCD. Even fine details can be printed more clearly and accurately, greatly improving the imaging clarity and printing accuracy of 3D printing.

[0057] The position of the Fresnel lens 150 between the light source and the LCD screen can more effectively distribute the light 400, ensuring that the light 400 is evenly irradiated to the entire LCD screen. This is particularly important for 3D printing because it ensures that each layer of resin can be evenly cured, whether in the center or at the edge of the screen. The result is that the surface quality of the printed object is higher and the internal structure is more uniform, thereby improving the overall printing quality and mechanical strength.

[0058] By optimizing the uniform distribution of light 400, not only the printing efficiency is improved, but also the energy waste is reduced. More uniform light distribution means that each LCD screen can get enough light, avoiding over-exposure and energy waste, which helps to improve the light efficiency of the light source to the printing surface. At the same time, more efficient use of light energy may also reduce the heat load of the device during operation, which helps to extend the service life of the device, especially for high-intensity, long-running printing tasks.

[0059] The technical solution of the utility model adopts a mounting bracket 110, a light source device 120, a Fresnel lens 150, a display screen 170 and a lens group 200 which are sequentially arranged on the mounting bracket 110 from top to bottom; the mounting bracket 110 is adapted to form an optical path layout, the display screen 170 forms a light-transmitting area matching the cross-sectional image required for printing after receiving a control signal, the Fresnel lens 150 converges the light 400 of the light source device 120 and projects it onto the display screen 170, and the light 400 passing through the light-transmitting area projects the cross-sectional image formed by the light-transmitting area out of the lens group 200 in proportion. The cross-sectional image of the display screen 170 is projected in proportion by the lens group 200, thereby solving the problem in the related art that the liquid crystal display screen 170 needs to be attached to the bottom of the material tray for bottom projection display molding, the liquid crystal display screen 170 is easily crushed, the service life of the liquid crystal display screen 170 is seriously shortened, and the printing speed is very slow. Placing the Fresnel lens 150 between the light source device 120 and the display screen 170 can reduce the size of the lens group 200, reduce costs and facilitate miniaturization of the equipment; and compared with the solution in which the Fresnel lens 150 is arranged between the lens group 200 and the display screen 170, the Fresnel lens 150 is directly located in the imaging path of the display screen 170 and the lens group 200. Because the design of the Fresnel lens 150 includes many small concave and convex surfaces or "edges", subtle textures or unevenness appear during the imaging process, affecting the smoothness and detail of the surface of the printed object. The present application effectively avoids the optical distortion and scattering problems caused by the Fresnel lens 150 being directly located in the imaging path of the display screen 170 and the lens group 200 in the related design by reconfiguring the position of the Fresnel lens 150. There is no device that affects the imaging quality between the display screen 170 and the lens group 200, thereby optimizing the imaging quality and improving the curing accuracy and quality during the printing process.

[0060] Reference Figure 1 In order to improve the optical performance of the imaging device 100 and enhance the quality and stability of the projection effect, the Fresnel lens 150 is close to the display screen 170 .

[0061] The close combination of the Fresnel lens 150 and the display screen 170 can reduce the scattering loss of the light 400 between the two, so that the light 400 enters the display screen 170 through the lens more concentratedly, reducing the impact of external interference factors on the projection effect, improving the light efficiency, and making the light path more stable; the Fresnel lens 150 close to the display screen 170 can effectively reduce the interference of the air medium between the lens and the display screen 170 on the light 400, reduce reflection and refraction losses, and help improve the clarity and quality of the projected image. The close design is conducive to reducing the size of the imaging device 100 and facilitating the miniaturization of the imaging device 100.

[0062] In order to improve the performance and quality of the imaging device 100, a UV glue layer 160 is formed between the Fresnel lens 150 and the display screen 170, and the Fresnel lens 150 and the display screen 170 are bonded and fixed by the UV glue layer 160. Specifically, the use of UV glue can ensure that there are no bubbles or gaps between the Fresnel lens 150 and the display screen 170, which helps to reduce the scattering and interference of the light 400 between the two and improve the optical performance of the projection system. In addition, the fixation with UV glue can ensure that the position of the lens and the display screen 170 is relatively stable, and it is not easy to move or loosen, so as to maintain the calibration and adjustment state of the projection system. Moreover, the UV glue can be bonded in a transparent state, so that the lens and the display screen 170 can be compactly combined, which helps to design a more compact projection device. It is worth mentioning that after the UV glue layer 160 is formed between the Fresnel lens 150 and the display screen 170, the UV glue layer 160 plays a heat-insulating role, can maintain a good bonding effect for a long time, and can ensure the stability and reliability of the imaging device 100 in long-term use.

[0063] Furthermore, the thickness of the UV adhesive layer 160 is 0.02 mm-0.5 mm, for example, the thickness of the UV adhesive layer 160 is 0.1 mm or 0.2 mm, which ensures the stability of the bonding, plays a protective role, and reduces the cost.

[0064] In order to control the projection range of the light 400 to ensure the clarity and focusing effect of the projection, in the horizontal projection direction, the projection area of ​​the lens group 200 is smaller than the projection area of ​​the Fresnel lens 150; further, there is a certain distance between the lens group 200 and the display screen 170, and the distance is based on ensuring that the light spot with the cross-sectional image shape can be projected to the lens group 200 in a clear manner. In addition, the small size of the lens group 200 can reduce costs and is also conducive to the miniaturization of the imaging device 100.

[0065] In order to make the light 400 emitted from the light source device 120 converge and pass through the display screen 170, in the horizontal projection direction, the projection area of ​​the Fresnel lens 150 is greater than or equal to the projection area of ​​the display screen 170, so that the light 400 obliquely passes through the display screen 170 and then enters the lens group 200, so that the size of the lens of the lens group 200 can be much smaller than the display screen 170, thereby saving costs.

[0066] Specifically, the lens group 200 is a Gauss lens or a Tessar lens or a Cooke triple lens. The Cooke triple lens is a lens design that uses three lenses, including a convex lens and two concave lenses. The Gauss lens is composed of several lens groups 200, including convex lenses and concave lenses, as well as appropriate curvature and spacing to achieve specific optical performance. By carefully designing the curvature and spacing of the lenses, the Gauss lens can effectively correct aberrations and provide clear and sharp images. The Tessar lens is usually composed of four lens groups 200, including a convex lens and three concave lenses. The Tessar lens has a relatively uniform optical performance, showing bright colors and high sharpness in the central area, while maintaining relatively good imaging quality in the edge area.

[0067] In order to ensure the clarity of the projection, the focal length of the lens group 200 is adjustable. Specifically, the display screen 170 can be regarded as a light-transmitting switch. The computer transmits the required printed section to the display screen 170. In the solution where the display screen 170 is a liquid crystal screen, the crystal part of the liquid crystal is arranged in a certain way to form a passage (light-transmitting area) for the light 400 to pass through. The part that does not form a light path (non-light-transmitting area) blocks the light 400. Finally, the cross-section formed by the light 400 transmitted by the lens group 200 is proportional to the cross-section of the light 400 emitted from the light-transmitting area. That is, the lens group 200 is regarded as the center of symmetry, and the light-transmitting area is displayed symmetrically along the lens group 200, so as to ensure the clarity of the final image, thereby ensuring the accuracy of the molded part after the photosensitive material is cured.

[0068] Specifically, the lens group 200 has the function of fixing the focal length or manually adjusting the focal length or automatically adjusting the focal length. The focal length is a measurement method for measuring the convergence or divergence of light in an optical system, and refers to the distance from the center of the lens to the focus of light convergence.

[0069] The utility model also proposes a photocurable 3D printer, which includes a frame, a material storage tank, a molding platform 300, a lifting mechanism and an imaging device 100. The specific structure of the imaging device 100 refers to the above embodiment. Since the photocurable 3D printer adopts all the technical solutions of all the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here. Among them, the imaging device 100, the lifting mechanism and the material storage tank are arranged on the frame, the material storage tank is arranged below the imaging device 100, and the material storage tank is used to place liquid photocurable materials; the molding platform 300 is fixedly connected to the lifting mechanism, the molding platform 300 is located above the material storage tank or the molding platform 300 is located in the material storage tank, and the lifting mechanism is used to drive the molding platform 300 to move relative to the material storage tank.

[0070] The above description is only a preferred embodiment of the utility model, and does not limit the patent scope of the utility model. All equivalent structural changes made by using the contents of the utility model specification and drawings under the concept of the utility model, or directly / indirectly used in other related technical fields are included in the patent protection scope of the utility model.

Claims

1. An imaging device for a light-curing 3D printer, characterized in that: include: Mounting bracket; as well as A light source device, a Fresnel lens, a display screen and a lens group are arranged on the mounting bracket in sequence from top to bottom; The Fresnel lens is located between the light source device and the display screen, and is used to collect the light emitted by the light source device. The collected light passes through the light-transmitting area of ​​the display screen and is imaged by the lens group.

2. The imaging device according to claim 1, wherein: The Fresnel lens is in close contact with the display screen.

3. The imaging device according to claim 2, characterized in that A UV adhesive layer is formed between the Fresnel lens and the display screen, and the Fresnel lens and the display screen are bonded and fixed by the UV adhesive layer.

4. The imaging device according to claim 1, wherein: In the horizontal projection direction, the projection area of ​​the lens group is smaller than the projection area of ​​the Fresnel lens.

5. The imaging device according to claim 1, wherein: In the horizontal projection direction, the projection area of ​​the Fresnel lens is greater than or equal to the projection area of ​​the display screen.

6. The imaging device according to claim 1, wherein: The lens group is a Gauss lens, a Tessar lens or a Cooke three-piece lens.

7. The imaging device according to claim 1, wherein: The focal length of the lens group is adjustable; and / or a light guiding structure is provided between the lens group and the display screen.

8. The imaging device according to claim 1, wherein: The light source device includes a light source composed of a plurality of light emitting diodes arranged in an array and / or a plurality of laser diodes arranged in an array, and a focusing lens for collimating the light of the light source; or, the light source device adopts a COB light source.

9. The imaging device according to claim 1, wherein: The Fresnel lens and the display screen are arranged in the mounting bracket, the light source device is arranged above the mounting bracket, the lens group is arranged below the mounting bracket, and a closed optical path channel is formed between the light source device, the mounting bracket and the lens group.

10. A light-curing 3D printer, characterized in that: include: A frame, an imaging device according to any one of claims 1 to 9, a material storage tank, a molding platform and a lifting mechanism; The imaging device, the lifting mechanism and the material storage trough are arranged on the frame, the material storage trough is arranged below the imaging device, and the material storage trough is used to place liquid photocurable material; the molding platform is fixedly connected to the lifting mechanism, and the lifting mechanism is used to drive the molding platform to extend into or move out of the material storage trough.

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