A projection device and a 3D printer for a biconvex matrix optical lens

Abstract

The present invention discloses a projection device and a 3D printer for a bi-convex matrix optical lens. The projection device includes: an LED array, a bi-convex matrix optical lens, and an LCD liquid crystal display screen arranged in sequence along the optical path from bottom to top; the LED array is composed of point light sources of multiple rows and multiple columns of UV ultraviolet LED chips; the bi-convex matrix optical lens is composed of bi-convex lenses with the same arrangement and the same number as the point light sources; the LED array is adapted to the bi-convex matrix optical lens; the ultraviolet light with a wavelength of 385-405 nm emitted by the point light source passes through the corresponding bi-convex lens to form parallel light and project it onto the LCD liquid crystal display screen. The projection device adopts a bi-convex matrix optical lens, and the spot consistency caused by the lens matrix arrangement and splicing seams is high, improving the uniformity of the overall spot; after the LED light energy of 385-405 nm is refracted, it becomes more precise parallel light with a smaller angle, which helps the 3D printer improve the printing success rate and efficiency.

Description

Technical Field

[0001] The present invention relates to the technical fields of UV-curing 3D printers and 3D printing technology, and particularly to a projection device and a 3D printer with a biconvex matrix optical lens. Background Art

[0002] Currently, there are three types of light-curing 3D printers: SLA, DLP, and LCD technology molding machines. In the SLA technology, the method used is to irradiate photosensitive resin with a laser. This method uses laser G-code to scan each model layer point by point from line to line with a laser, and then irradiates the photosensitive resin with a fast laser. The light source used in the DLP technology comes from a projector. The projector irradiates the model part as a planar image onto the resin solution to solidify. Using this method, a surface is formed at one time, and the printing time only depends on the height of the object to be printed. The LCD technology light-curing 3D printer has the advantages of high precision and low equipment price.

[0003] However, for the LCD technology light-curing 3D printer, the problem currently existing in the industry is the grid-like bright or dark light spots that appear at the splicing seams in the matrix arrangement, resulting in low overall light spot consistency and uniformity, low precision due to uneven light energy, inability to achieve fast printing, and thus low printing efficiency and high cost.

[0004] When the uniformity of the light energy projected onto the exposure screen is insufficient, the light energy of 385 - 405 nm received in the liquid resin cartridge is uneven, resulting in a decrease in printing precision; the printing time of the part with lower light energy is prolonged.

[0005] In addition, for the UV-curing of 3D printers, high-precision printing needs to be achieved through highly uniform light energy and precise parallel light. Therefore, to achieve the effect of high-precision and fast printing for the whole machine, the requirements for the uniformity of the overall light spot and small angles are a major pain point in the current industry. Summary of the Invention

[0006] The main purpose of the present invention is to provide a projection device and a 3D printer with a biconvex matrix optical lens that at least partially solve the above technical problems.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] In a first aspect, an embodiment of the present invention provides a projection device with a biconvex matrix optical lens, including: an LED array, a biconvex matrix optical lens, and an LCD liquid crystal display disposed in sequence along the optical path from bottom to top;

[0009] The LED array is composed of point light sources of multiple rows and multiple columns of UV ultraviolet LED chips;

[0010] The double-convex matrix optical lens is composed of double-convex lenses with the same arrangement and the same number as the point light source; the LED array is adapted to the double-convex matrix optical lens;

[0011] The 385-405 nm ultraviolet light emitted by the point light source passes through the corresponding double-convex lens, forming parallel light and projecting it onto the LCD liquid crystal display screen.

[0012] Furthermore, the UV ultraviolet LED chip is cured on an aluminum substrate or a copper substrate;

[0013] The aluminum substrate or the copper substrate is fixed on a radiator;

[0014] A bracket is further arranged on the radiator; the double-convex matrix optical lens is fixed on the bracket.

[0015] Furthermore, the UV ultraviolet LED chip selects an LED with a 50% light intensity angle of 60° or 90°.

[0016] Furthermore, the material of the double-convex matrix optical lens is optical-grade PMMA.

[0017] Furthermore, the position of the point light source coincides with the focal point of the corresponding double-convex lens.

[0018] Furthermore, the curvature of the incident light surface and the outgoing light surface of the double-convex lens is different, and the curvature of the incident light surface is smaller than the curvature of the outgoing light surface.

[0019] Furthermore, the thickness of the double-convex lens is 5 mm to 25 mm, and the thickness uniformly transitions from the edge to the center.

[0020] Furthermore, the size of the LCD liquid crystal display screen is the same as the size of the LED array.

[0021] In a second aspect, an embodiment of the present invention further provides a 3D printer, using a projection device with a double-convex matrix optical lens as described in any one of the above embodiments.

[0022] The present invention provides a projection device with a double-convex matrix optical lens, comprising: an LED array, a double-convex matrix optical lens, and an LCD liquid crystal display, which are arranged in sequence along the optical path from bottom to top; the LED array is composed of point light sources of multiple rows and columns of UV ultraviolet LED chips; the double-convex matrix optical lens is composed of double-convex lenses with the same arrangement and the same number as the point light sources; the LED array is adapted to the double-convex matrix optical lens; the ultraviolet light with a wavelength of 385-405 nm emitted by the point light sources passes through the corresponding double-convex lenses, forming parallel light and projecting it onto the LCD liquid crystal display. This projection device uses a double-convex matrix optical lens, and the spot consistency caused by the lens matrix arrangement and splicing seams is high, improving the uniformity of the overall spot; after the LED light energy of 385-405 nm is refracted, it becomes more precise parallel light with a smaller angle, which helps the 3D printer improve the printing success rate and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 FIG. is a schematic structural diagram of the projection device with a double-convex matrix optical lens provided by an embodiment of the present invention;

[0024] Figure 2 FIG. is a perspective view of the projection device with a double-convex matrix optical lens provided by an embodiment of the present invention;

[0025] Figure 3a FIG. is a plan view of the projection device with a double-convex matrix optical lens provided by an embodiment of the present invention;

[0026] Figure 3b is Figure 3a a sectional view taken along line AA in ;

[0027] Figure 3c is Figure 3b a sectional view taken along line BB in ;

[0028] Figure 4 FIG. is a schematic diagram showing the coincidence of the position of the point light source and the focus of the corresponding double-convex lens provided by an embodiment of the present invention;

[0029] Figure 5 FIG. is a schematic optical path diagram provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] In order to make the technical means, creative features, achieved purposes and effects of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.

[0031] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0032] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] Embodiment 1:

[0034] Referring to Figure 1 As shown, a projection device of a double-convex matrix optical lens provided by the present invention can achieve the purpose of distributing the light energy of the curing light source for UV light curing of a 3D printer over a large area on the exposure screen, making it as parallel as possible, with the angle being as small as possible and the light efficiency being as high as possible.

[0035] The projection device includes: an LED array 1, a double-convex matrix optical lens 2, and an LCD liquid crystal display screen 3 arranged in sequence along the optical path from bottom to top;

[0036] Among them, the LED array 1 is composed of point light sources of multiple rows and multiple columns of UV ultraviolet LED chips 11; the double-convex matrix optical lens 2 is composed of double-convex lenses 21 with the same arrangement and the same number as the point light sources; the LED array is adapted to the double-convex matrix optical lens, corresponding to each other in number and position; the curvature of the light incident surface and the light exit surface of the double-convex lens is different, and the curvature of the light incident surface is smaller than that of the light exit surface; the thickness of the double-convex lens is 5 mm to 25 mm, and the thickness gradually transitions uniformly from the edge to the center. The ultraviolet light with a wavelength of 385 - 405 nm emitted by the point light source passes through the corresponding double-convex lens 21 and forms parallel light projected onto the LCD liquid crystal display screen 3, and the size of the LCD liquid crystal display screen is the same as that of the LED array.

[0037] The working principles of the components such as the 3D printer UV light curing light source, i.e., the LED array 1, the double-convex matrix optical lens 2, and the exposure screen, i.e., the LCD liquid crystal display screen 3, are as Figure 2As shown in the figure. The technology that uses an LCD as a light source, namely LCD mask photocuring: uses ultraviolet light of 385 - 405 nm (the same as DLP), plus an LCD panel as a technology for selective light transmission (mainly a black-and-white LCD panel).

[0038] In this embodiment, multiple single point light sources emit light simultaneously. The biconvex matrix optical lens can turn such multi-point light sources into parallel light, achieving a highly uniform and high-light-efficiency light spot projected onto the LCD liquid crystal display screen. The array of 385 - 405 nm point light sources can emit light that can cure liquid photosensitive resin, and is provided with multiple linear array distributions to improve the energy and irradiation range of the light. The UVLED (point light source) has the advantages of long life, no thermal radiation, its life is not affected by the number of opening and closing times, high energy, uniform irradiation, improving production efficiency, being free of toxic substances, and being safer and more environmentally friendly than traditional array point light sources.

[0039] UV photocuring has an important application in 3D printing. It mainly uses ultraviolet light to scan the surface of liquid photosensitive resin, generating a certain thickness of thin layer each time, and generating an object layer by layer from the bottom. The 3D printing of UV photocuring is completed through the transformation of the polymer from liquid to solid state.

[0040] This projection device uses a biconvex matrix optical lens. The high consistency of the light spot caused by the lens matrix arrangement splicing seam improves the uniformity of the overall light spot; after the LED light energy of 385 - 405 nm is refracted, it becomes a more precise parallel light with a smaller angle, which helps the 3D printer improve the printing success rate and efficiency.

[0041] Furthermore, as Figure 1 shown, the UV ultraviolet LED chip 11 is cured on an aluminum substrate or a copper substrate 12; and the aluminum substrate or the copper substrate 12 is fixed on the radiator 13; a black bracket 22 is also provided above the radiator. The biconvex lens 21 of the biconvex matrix optical lens 2 is fixed on the black bracket 22; the purpose of choosing black is to absorb light, and at the same time, light-absorbing patterns can be provided on it. The material of the biconvex matrix optical lens can preferably be optical-grade PMMA, which is a kind of polymer, also known as acrylic or plexiglass, and has the advantages of high transparency, low price, easy machining, etc. It can replace commonly used glass, is relatively lighter in mass than glass, and has a higher light transmittance than glass.

[0042] As Figures 3a - 3b shown, it is a biconvex matrix optical lens for the 3D printing UV photocuring light source, fixed on a black bracket. The black bracket is fixed on an aluminum profile radiator, and the MCPCB (aluminum substrate) is fixed on the aluminum profile radiator; the optical lens is manufactured by ultra-precision machining with a CNC mold and then by an ultra-precision injection molding process.

[0043] After the optical design is completed, the Monte Carlo method can be used for ray simulation to obtain the light energy distribution of 405 nm on the exposure screen. The light energy distribution on the entire exposure screen has a uniformity of more than 95%; the illuminance uniformity of the exposure screen (black and white LCD) = minimum illuminance value / average illuminance value, and the minimum illuminance value is calculated by the point-by-point calculation method.

[0044] Furthermore, the UV ultraviolet LED chip 1 can select an LED with a 50% light intensity angle of 60° or 90°. Combined with the above-mentioned biconvex matrix optical lens, the following three purposes can be achieved:

[0045] a. By 3D printing the biconvex matrix optical lens of the UV light-curing light source, after the light energy of the UV 385 - 405 nm LED with an angle of 60° or 90° is refracted, it becomes parallel light or nearly parallel light energy with a left and right angle less than 1.5° (the smaller the angle, the better).

[0046] b. At the same time, a uniform light energy distribution of 385 - 405 nm is obtained on the exposure screen. The measured uniformity of the optical machine reaches more than 90%. It makes up for the defects of traditional LCDs in 3D printing light curing; at the same time, by using the biconvex matrix optical lens, the collimation and uniformity of light are successfully solved, and the uniformity of the optical machine reaches more than 90%.

[0047] c. Compared with the traditional plano-convex matrix optical lens, the biconvex matrix optical lens can obtain higher light energy utilization efficiency, which is beneficial for energy conservation or obtaining higher 3D printing efficiency.

[0048] Furthermore, during the implementation of the specific embodiment, the position of the point light source can be coincident with the focus of the corresponding biconvex lens, as Figure 4 shown:

[0049] First, design a biconvex collimating lens according to Snell's law of light rays. When light rays are refracted through the interface of two media, determine the propagation directions of the incident light ray and the refracted light ray. The plane formed by the incident light ray and the normal of the interface passing through the incident point is called the incident plane. The angles between the incident light ray and the refracted light ray and the normal are called the incident angle and the refracted angle respectively, denoted by θi and θt. The refracted light ray is in the incident plane, and the ratio of the sines of the incident angle and the refracted angle is a constant, denoted by n as the refractive index: sinθi / sinθt = n. The focus of the biconvex matrix optical lens of the 3D printed UV light-curing light source coincides with the position of the 385 - 405 nm point light source, thus generating parallel light.

[0050] In addition, in the current UV-curing 3D printer industry, machines for different fields have different requirements for the uniformity and energy of the light source spot. For consumer-grade machines, the general uniformity requirement is above 80%, and the energy is above 3500 uW / cm. Consumer products have high requirements for cost control. Currently, the maximum size of a single plano-convex matrix collimated light source in the industry is below 28 mm, and 28 mm for a single one is the limit.

[0051] To improve the cost performance of the light source, in the embodiments of the present invention, a single lens can be made to be below 42 mm at most. Such a large arrangement cannot meet the requirements for the spot uniformity and transmittance of the UV-curing 3D printer industry. However, according to the UV encapsulation accuracy, double-sided optical refraction can be used to achieve the effects of large size and high uniformity. Through high-precision optical design, ultra-precision mold processing, and ultra-precision injection molding, specific requirements of the industry are met, and this double-convex matrix light source is specially developed.

[0052] Furthermore, according to LCD screens of different specifications and sizes in the industry, different customers have different requirements for energy and uniformity, and thus different requirements for the cost of the light source. In the embodiments of the present invention, double-sided optics can be used to reduce the number of single LEDs by up to about 35% for the same specification and size of the screen to achieve higher light energy utilization.

[0053] As Figure 5 shown, a 385-405 nm ultraviolet LED chip at the focal position emits light rays with a 60° angle at 50% light intensity. After passing through the optical light-incident surface of the double-convex lens, the light energy is refracted for the first time. The double-convex aspherical optical surface is conducive to further converging the light energy towards the exposure screen, improving the LED light energy utilization rate of the system. The 385-405 nm light rays after collimation are projected onto the exposure screen, obtaining a very small angle, uniformity, and high light efficiency. During the production process of this double-convex matrix optical lens, for example, when it is also realized by 3D printing, in order to reduce the error of STP file conversion, an optical surface equation can be used to manufacture the optical mold.

[0054] Embodiment 2:

[0055] Based on the same inventive concept, the embodiments of the present invention further provide a 3D printer using a projection device with the double-convex matrix optical lens provided in Embodiment 1 above, and its working principle is as follows:

[0056] 1. The light energy of 385-405 nm is emitted from the LED, and an LED with a 60° or 90° angle at 50% light intensity is selected;

[0057] 2. The light energy passes through the lower surface of the lens, forms the first refraction, and enters the double-convex optical lens;

[0058] 3. The light energy travels about 20 mm and then refracts out of the lens, forming parallel light, features: high uniformity, high light efficiency;

[0059] 4. Uniform parallel light is projected onto a highly transparent black-and-white LCD;

[0060] 5. The light energy of 385 - 405 nm that is not blocked passes through the black-and-white LCD and then enters the liquid resin cartridge.

[0061] 6. The light energy of 385 - 405 nm cures the resin in the same part of the liquid resin cartridge to achieve the 3D printing function: the liquid resin at the specified part becomes solid; the part not irradiated by the light energy of 385 - 405 nm remains unchanged as liquid resin. Cooperate with the lifting device to complete the 3D object printing.

[0062] In this embodiment, after the light emitted by the 385 - 405 nm LED array passes through the biconvex matrix optical lens, the optical path propagation direction is perpendicular to the LCD liquid crystal display screen, and the distance from the liquid surface of the photocuring material is less than 5 cm. The present invention can improve the printing success rate and efficiency of the product on the premise of reducing production costs.

[0063] The above shows and describes the basic principles, main features and advantages of the present invention. Specific examples are used in this article to elaborate on the optical principles and functions of the present invention. The above description of the embodiments is only used to help understand the method and core idea of the present invention. At the same time, in the several embodiments provided by the present invention, it should be understood that the disclosed device can be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the above division of units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. For those of ordinary skill in the art, according to the ideas and methods of the present invention, there will be changes in specific implementation and application. Therefore, the content of the present invention should not be construed as a limitation to the present invention. As long as the ideas and methods are similar or identical, they are all covered by the present invention.

Claims

1. A projection device of a biconvex matrix optical lens, characterized in that, Including: An LED array, a biconvex matrix optical lens, and an LCD liquid crystal display arranged in sequence along the optical path from bottom to top; The LED array is composed of point light sources of multiple rows and columns of UV ultraviolet LED chips; The UV ultraviolet LED chips are selected as LEDs with a 50% light intensity angle of 60° or 90°; The biconvex matrix optical lens is composed of biconvex lenses with the same arrangement and the same number as the point light sources; the LED array is adapted to the biconvex matrix optical lens; The curvature of the light incident surface of the biconvex lens is different from that of the light exit surface, and the curvature of the light incident surface is smaller than that of the light exit surface; The biconvex lens is designed according to Snell's law of light; The 385-405nm ultraviolet light emitted by the point light source passes through the corresponding biconvex lens and forms parallel light projected onto the LCD liquid crystal display.

2. The projection device of a biconvex matrix optical lens according to claim 1, characterized in that, The UV ultraviolet LED chips are cured on an aluminum substrate or a copper substrate; The aluminum substrate or the copper substrate is fixed on a radiator; A bracket is further provided on the radiator; the biconvex matrix optical lens is fixed on the bracket.

3. The projection device of a biconvex matrix optical lens according to claim 1, characterized in that, The material of the biconvex matrix optical lens is optical-grade PMMA.

4. A projection device for a biconvex matrix optical lens according to claim 1, characterized in that, The position of the point light source coincides with the focus of the corresponding biconvex lens.

5. The projection device of a double-convex matrix optical lens according to claim 1, characterized in that, The thickness of the biconvex lens is 5mm to 25mm, and the thickness uniformly transitions from the edge to the center.

6. The projection device of a double-convex matrix optical lens according to claim 1, characterized in that, The size of the LCD liquid crystal display is the same as that of the LED array.

7. A 3D printer, characterized in that, A projection device using the biconvex matrix optical lens according to any one of claims 1-6.

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