KR102462055B1 - Light irradiator for resin printer - Google Patents

Abstract

An LED structure of a resin printer capable of emitting light with uniform brightness of LCD is disclosed. A light radiation device of a resin printer comprises: a light source for radiating light to solidify the resin; an LCD located on an upper end of the light source; a lens array located between the light source and LCD, and consisting of a plurality of lenses to focus the light radiated from the light source and transmit the same to the LCD; a photodetector located at a lower end of the lens array and detecting an amount of light emitted from the light source and reflected from the LCD; and a control unit adjusting an intensity of the light radiated from the light source according to the amount of light detected by the photodetector.

Description

Light irradiator for resin printer

The present invention relates to a light irradiation apparatus for a resin printer, and more particularly, to a light irradiation apparatus for a resin printer capable of uniformly emitting the luminance of an LCD.

Recently, a 3D printer for producing a three-dimensional molded product using 3D drawing data designed with a three-dimensional modeling tool is widely used. A 3D printer manufactures a three-dimensional molded article by stacking materials such as liquid, powder-type polymer, and metal in a stacking manner according to three-dimensional 3D drawing data. Accordingly, there is an advantage in that the shape can be easily modified during actual prototype production, and the production cost, material cost, and labor cost can be reduced. 3D printers are used in various fields such as automobiles, aviation, architecture, medical care, home appliances, and toys.

The 3D printer uses the SLA (Stereo Lithography Apparatus) method to cure the injected part by injecting a laser into the photocurable resin, the SLS (Selective Laser Sintering) method for sintering using a functional polymer or metal powder, and extruding the molten resin. FDM (Fused Deposition Modeling) method for molding, DMT (Laser-aid Direct Metal Tooling) method for directly forming metal with a high-power laser beam, LOM (Laminated Object Manufacturing) method for mechanical bonding molding, storage tank where photocurable resin is stored A DLP (Digital Light Processing) method of curing by irradiating light downwards is known.

Among them, the DLP type 3D printer has been disclosed in US Patent US8110135 "PROCESS AND FREEFORM FABRICATION SYSTEM FOR PRODUCING A THREE-DIMENSIONAL OBJECT". However, since the DLP type 3D printer laminates one side at a time, the printing time is short, but there is a disadvantage in that the resolution varies according to the printing area.

Recently, a method using an LCD panel has been proposed. It is known that the light from the light source reaches the LCD panel and the photocurable resin in the masked area is cured. LCD-type lighting methods can be broadly divided into reflection type, single lens type, and multi-lens array type.

The reflective type is a method of irradiating the light source to the LCD panel using a reflector (mirror), and has the advantage of using a small light source, but has a disadvantage in that the intensity is weak and the irradiation area is non-uniform.

The single lens type can increase the intensity of the light source by irradiating each light source to the LCD panel using each single circular spherical or aspherical lens, but has a disadvantage in that the irradiation area of each lens overlaps.

The multi-lens array has the advantage of increasing the intensity of the light source and minimizing the overlapping irradiation area in a form in which a plurality of spherical or aspherical lenses are bonded. However, there is a disadvantage that the intensity of a plurality of light sources irradiated to the LCD panel is not the same, which leads to an imbalance in 3D output. Accordingly, there is a problem in that the intensity of light reaching the LCD panel is not uniform at the center portion and both edge portions. When the intensity of light irradiated to the LCD panel is non-uniform, the degree of curing of the liquid molding material is changed, and thus, there is a problem in that the quality of the molded product is deteriorated.

In addition, since UV rays are not uniformly irradiated to all LCD surfaces of the LCD module during operation of the 3D printer, the usage time and expected remaining time may be different for each zone, so it is important to equalize the intensity of light irradiated from the light source. need.

Accordingly, it is an object of the present invention to provide a light irradiation device for a resin printer capable of reaching the LCD with a uniform intensity as a whole by checking the variation in the amount of light emitted from a light source.

Another object of the present invention is to provide a light irradiation apparatus for a resin printer capable of reducing the variation in the amount of light between light sources by installing a photodetector next to the light source.

In order to achieve the above object, the present invention is a light source irradiating light for solidifying a resin, an LCD positioned on top of the light source, positioned between the light source and the LCD, and focusing the light irradiated from the light source to the LCD a lens array consisting of a plurality of lenses so as to It provides a light irradiation device of a resin printer comprising a control unit for controlling.

The light irradiation device of the resin printer according to the present invention records the amount of light emitted from the light source by installing a photo diode next to the light source, thereby reducing the variation in the amount of light between the light sources. A light source of uniform intensity can be reached.

1 is a view showing the structure of a light irradiation device of a resin printer according to an embodiment of the present invention.
Figure 2 is a view showing the operation of the light irradiation device of the resin printer according to an embodiment of the present invention.
3 is a view showing an optical path when curvature exists in the upper part and lower part of the lens of the light irradiation apparatus of the resin printer according to an embodiment of the present invention.
4 is a view showing an optical path when the curvature is present in the upper part of the lens of the light irradiation device of the resin printer according to an embodiment of the present invention, and the radius of curvature of the lower part of the lens is in the form of infinity.

Hereinafter, the present invention will be described in more detail.

1 is a light irradiation apparatus of a resin printer according to an embodiment of the present invention, and shows the structure of the light irradiation apparatus used in the 3D printing apparatus. The light irradiation device of the resin printer according to the present invention is a light source irradiating light to solidify a resin, an LCD positioned at the top of the light source, and positioned between the light source and the LCD, and condensing the light irradiated from the light source to the LCD. A lens array consisting of a plurality of lenses to transmit, a photodetector that is located at the bottom of the lens array and detects the amount of light emitted from the light source and reflected from the LCD, and the light emitted from the light source according to the amount of light detected by the photodetector It includes a control unit for adjusting the intensity.

1, a lens array 5 composed of a plurality of lenses to focus the light irradiated from the light source and deliver it to the LCD, a light source irradiating light to solidify the resin, and the light source irradiated from the light source and reflected from the LCD A board 20 including a photodetector for detecting the amount of light, a separator 10 existing between the lens array 5 and the board 20, and located at the bottom of the board to reduce the heat of the light source It includes a heat sink 30 that radiates heat.

In the lens array 5, a plurality of lenses are uniformly arranged to form one structure, and the light irradiated from the light source is focused and transmitted to the LCD, and the intensity of the light source over the entire area of the LCD is equalize. Specifically, the lens array 5 is a structure formed by arranging a plurality of lenses, and the size of the lens array is preferably equal to or large enough to cover the light emitting area of the LCD. The number of lenses included in the lens array 5 is the same as the number of light sources formed on the UV LED board to be described later.

In the lens array 5, a plurality of lenses can transmit the luminous flux of each UV LED to the LCD panel. Therefore, it is possible to uniformly transmit the light source to the LCD to make the degree of curing of the photocurable resin uniform. As the lens of the lens array, a commonly used lens may be used. For example, a lens with curvature at both the top and bottom of the lens (e.g., when the radius of curvature at the bottom of the lens is not infinity) or a lens with curvature only at the top of the lens and flat at the bottom (e.g. For example, when the radius of curvature of the lower part of the lens is infinity) can be used.

The separator 10 is a structure that supports between the lens array and the board 20 to be described later, and may have a form in which a plurality of cells in a grid pattern with perforated upper and lower ends are formed. The separator is a structure for isolating a plurality of light sources so as not to affect each other's area. Specifically, as a light source to be described later, there are a plurality of light sources. Since it is preferable that one light source corresponds to one lens of the lens array, a separator is installed between the lens array and the light source so that light from another light source is affected. It is blocked so as not to give light to the LCD, which will be described later, so that light can be uniformly transmitted. The number of compartments in the separator is equal to the number of lenses in the lens array 5 .

A light source 22 for solidifying the resin by irradiating light upwards, and a photo diode 24 as a sensor for detecting the amount of light of the light source are present on the board 20 as one plate. The board 20 is formed at the lower end of the lens array, specifically, at the lower end of the separator, and is a two-dimensional flat plate. The light source is preferably an LED (light emitting element). The light source 22 may serve as a backlight of an LCD to be described later. When a voltage is applied to the light source, light is emitted. At this time, the light source emits light at a predetermined divergent angle. Preferably, the divergence angle of the light source is as large as or larger than the lens diameter of the lens array.

The board 20 includes a plurality of light sources and photodetectors, and in particular, the light sources and photodetectors are positioned adjacent to each other. Specifically, when a voltage is applied to the light source, the light emits light and is reflected by the LCD, and a photodetector is installed at a position where the reflected light returns, and the light amount of the light source reflected by the LCD is measured by the photodetector.

The amount of light of the light source present on the board 20 is detected and recorded by a photodetector. Preferably, each light source detects an amount of light in a photodetector formed at an adjacent position. The photodetector detects and records the light amount of the light source, checks the recorded deviation of the light amount of each light source, and transmits it to the controller to correct it to the same value to adjust the brightness (intensity) of the light source .

In addition, it is preferable that the light source and the photodetector are installed equal to the number of lenses included in the array lens array, and it is more preferable that one light source and the photodetector correspond to each lens. The number of light sources and photodetectors is, for example, 15 or 24, respectively.

The heat sink 30 is for heat dissipation of the light source and the photodetector, and is formed at the bottom of the board. The heat sink is a heat dissipating material attached to prevent temperature rise of the light source and the photodetector, and a cooling fan may be further provided under the heat sink if necessary.

Although not shown in FIG. 1, the light irradiation apparatus of the resin printer according to the present invention includes an LCD. The LCD is located on the upper end of the light source, specifically, the upper end of the lens array. The LCD divides the 3D design data of the type to be made into each tomographic image with a computer, and then transmits it to the LCD to realize (output) the tomographic image. When the light source is irradiated to the LCD, the masked portion is reflected, the area on which the tomographic image is output is passed, and the light source is irradiated to the photocurable resin present on the upper part of the LCD, which will be described later. The photo-curable resin is cured in the form of a single-layer image output from the LCD, and this can be repeated to obtain a 3D output in a desired shape.

Although not shown in the drawings, a storage container for storing a photocurable resin and a 3D output formed by photocuring the photocurable resin, which can be generally used in 3D printers, are sliced and stacked on the upper part of the LCD. It includes, and may further include a printer driver for performing the operation of the 3D printer. The water tank and platform can apply the storage container and build plate used in a general LCD type 3D printer. It is common to the water tank (VAT) used in the LCD-type 3D printer, and a water tank (VAT) of the prior art may be utilized.

2 is a view showing the operation of the light irradiation device of the resin printer according to an embodiment of the present invention, Figure 3 is a view showing the operation of the light irradiation device of the resin printer according to another embodiment of the present invention, the resin printer It is a view showing the optical path when curvature exists in the upper part and lower part of the lens of the light irradiation device. 2 and 3 , first, a voltage is sequentially applied to the plurality of light sources 22 installed on the board 20 . A voltage may be applied to the light source 22 in a general manner. When a voltage is applied to the light source 22, light is emitted according to the divergence angle of the light source. Preferably, the diverging angle of the light source 22 is suitable for or larger than the diameter of the lens of the lens array.

The light emitted from the light source 22 passes through the separator 10 and passes through the lenses arranged in the lens array 5 . The lens array according to FIG. 2 uses a lens having a curvature only in the upper part and a flat lens in the lower part, and the lens array according to FIG. 3 uses a lens having a curvature in the upper part and the lower part. It can be seen that light irradiation is made. For example, when a voltage is applied to the first light source (LED, 22) of the board to emit light, the light passes through the lens corresponding to the first light source and is incident on the LCD 1 (blue in FIGS. 2 and 3). ray direction). As such, it can be seen that one light source corresponds to one lens.

The light passing through the lens is incident on the LCD 1 located on the top of the lens array. The LCD 1 is irradiated with a light source in a state in which the remaining part except for the output area is masked.

The light ray incident on the LCD 1 is reflected on the masked portion of the LCD, and is incident on the photo detector PD located adjacent to the first light source (LED, 22) of the board (red in FIGS. 2 and 3 ). ray direction).

The light source incident on the LCD is reflected, passes through the lens and the separator that have passed when the LCD is incident again in the reverse direction, and is incident on the photodetector PD 24 formed at a position adjacent to the light source. The photodetector 24 detects, for example, the amount of light of the first light source 22 and stores it. By recording and storing the light amount of each light source (for example, the second light source to the N light source) in each photodetector 24 in the same manner as described above, the deviation of the light amount of the light source can be checked.

4 is a view showing the operation of the light irradiation device of the resin printer according to another embodiment of the present invention, when the curvature exists in the upper part of the lens of the light irradiation device of the resin printer, and the radius of curvature of the lower part of the lens is in the form of infinity; A diagram showing the path of As shown in FIG. 4 , when the lower portion of the lens of the lens array 5 is flat, the emitted light is incident on the light source side of the planar portion of the lens, and the amount of light reflected from the flat portion of the lens is measured. Further measurements can be made in the detector 24 . For example, when a voltage is applied to the No. 1 light source (LED, 22) of the board to emit light, the light is incident on the flat part (lower part) of the lens corresponding to the No. 1 light source (blue light direction in FIG. 4), The light incident on the planar part (lower part) of the lens is reflected by the plane part (lower part) of the lens and is incident on the photodetector 24 located adjacent to the first light source 22 of the board (the red ray in FIG. 4 ). direction).

When the lens array 5 uses a lens having a curvature only in the upper part and a flat lower part, the intensity of the light quantity of the light source reflected from the lower part (flat part) of the lens is higher than the light quantity of the light source reflected from the LCD. Since is relatively large, it is possible to further detect (measure) the amount of light from the light source reflected from the lower portion (planar portion) of the lens.

Accordingly, when a lens having a curvature only in the upper portion and a flat lower portion is used, a method of measuring the amount of light reflected from the LCD and a method of measuring the amount of light reflected from the lower portion (planar portion) of the lens can detect the amount of light from the light source. Measuring the amount of light of the light source by the photodetector is the same.

According to the amount of light detected by the light detector 24, it is transmitted to a control unit that adjusts the intensity of the light emitted from the light source 22, so that the deviation of the light source is small, so that the light source can be uniformly transmitted to the LCD 1 do.

The control unit calibrates the light amounts of all light sources so that the light amounts of all the light sources have the same value by checking the deviation of the light amounts of the plurality of light sources. Specifically, by using the ratio of the amount of light to the voltage applied to the light source, a calibration chart is made and using the ratio, it is possible to obtain a voltage having a suitable value in which the deviation of the light source is small. A voltage having a suitable value is applied to each of the light sources. By applying the corrected voltage to the light source, it is checked whether the brightness of the LCD is uniform as a whole, and the data is stored to end calibration. In addition, the brightness of the LCD can be checked and corrected by using the value of the current instead of the voltage.

That is, the light source of uniform intensity as a whole emits light, so that the brightness of the light source can be adjusted to uniformly emit the luminance of the LCD. By installing a detector, it is possible to correct the brightness (intensity) of each light source so that it becomes the same value.

If the brightness (intensity) of the light source is uniformly corrected by the light irradiation device of the resin printer according to the present invention, the light source is irradiated to the LCD, and the light source is uniformly irradiated to the output portion of each layer transmitted to the LCD. , the portion irradiated with the light source is cured, and by repeating this, a 3D output is formed.

The lens array of the light irradiation device of the resin printer according to the present invention uses a plurality of lenses to uniformly transmit the light source to the LCD, thereby making the degree of curing of the photocurable resin uniform. In addition, the board has a structure for uniformly emitting the luminance of the LCD, and by installing a photodetector next to the light source, obtains the light amount of the light source reflected on the LCD, so that it can be adjusted to reduce the light amount deviation between the light sources.

Claims (9)

a light source irradiating light to solidify the resin;
an LCD positioned on the upper end of the light source, outputting a tomographic image of a desired shape, and irradiating light onto the resin in the region where the tomographic image is output;
a lens array positioned between the light source and the LCD, the lens array including a plurality of lenses to focus the light irradiated from the light source and deliver it to the LCD;
a photodetector positioned at the bottom of the lens array and detecting the amount of light emitted from the light source and reflected from the LCD; and
And a control unit for adjusting the intensity of the light irradiated from the light source according to the amount of light detected by the photodetector,
The light source and the light detector are present in a board that is one plate, the light irradiation device of the resin printer. The light irradiation apparatus of claim 1, wherein the lens array equalizes the intensity of the light source over the entire area of the LCD. delete The light irradiation apparatus of claim 1, wherein the light source and the light detector are located adjacent to each other. The light irradiation apparatus of claim 1, wherein a separator is positioned between the lens array and the board. The light irradiation apparatus of claim 1, which is located at the bottom of the board and includes a heat sink for dissipating heat from a light source and a photodetector. The light irradiation device of claim 1, wherein the light source is an LED. The light irradiation apparatus of claim 1, wherein the array lens is a lens having curvature in both upper and lower portions. The method according to claim 1, wherein when the array lens has a curvature only in the upper portion and a flat lens in the lower portion, the light irradiated from the light source is focused and transmitted to the lower portion of the lens, and the amount of light reflected from the lower portion of the lens is measured. The light irradiation apparatus of the resin printer which detects further.

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