Patent Application
20150290876
The present application claims the benefit of Chinese patent application number 201410137959.X, filed on Apr. 9, 2014, the disclosure of which is hereby incorporated by reference in its entirely.
The present invention relates to rapid prototyping technology, and more particularly relates to a stereolithographic apparatus and method.
The rapid prototyping technology is a kind of advanced manufacturing technology, which is based on CAD (computer-aided-design) and CAM (computer-aided manufacturing) technology, laser technology, CNC (computer numerical control) technology, precision servo driving technology, new photo curing materials and so on. The rapid prototyping production technology is considered as a key technology of new products developments in manufacturing enterprises, which can promote product innovation, shorten the development cycle of new products and improve the competitiveness of products. The known rapid prototyping method includes stereo lithography appearance method, laminated object manufacturing method, selective laser sintering method, fused deposition modelling method, three dimension printing method, and solid ground curing method.
One of the most common rapid prototyping technologies is stereolithographic process. The principle of the stereolithographic process is that light source emits light through a transparent image displayed on the imaging means and project light onto the liquid photosensitive resin, the liquid photosensitive resin will solidify under exposure to the light based on the liquid photosensitive resin's light curing characteristic, and then a solid layer is formed. When one solid layer is built, scan remain resin for forming the next solid layer, and the new solid layer is fixed on the previous solid layer, repeat these steps to form a complete part. However, in the related art, the light source may be a point light source that emits stray light. The stray light will cure some liquid photosensitive resin that should not be cured.
An objective of this application is to provide a stereolithographic apparatus and method, which is equipped with a area light source that emits substantially parallel light.
In one aspect, the present invention relates to a stereolithographic apparatus comprising a container for containing liquid photosensitive resin; an imaging means for displaying a contour of a two-dimensional image with a transparent region inside the contour; a light source device for projecting light onto a surface of the liquid photosensitive resin through the transparent region to cure the liquid photosensitive resin; wherein, the imaging means is disposed between the container and the light source device; the light source device is a area light source emitting substantially panel light.
In another aspect, the present invention relates to a stereolithographic method for producing an object having multiple cross-sections, the method comprising: step 1: filling a container with liquid photosensitive resin; step 2: displaying a contour of one of the cross-sections of the object on an imaging means with a transparent region inside the contour; step 3: projecting light onto a surface of the liquid photosensitive resin through the transparent region by a light source device, which is a area light source emitting substantially panel light, to cure the liquid photosensitive resin and convert it to a solid layer corresponding to the cross-section of the object; step 4: determining whether all of the cross-sections have been built, if all of the cross-sections have been built, the process completed; otherwise, executing the next step; step 5: lifting the previous solid layer, refilling the liquid photosensitive resin and repeating the steps 2-4 to form the object.
In yet another aspect, the present invention relates to a stereolithographic apparatus comprising: a vat for holding liquid curable resin; an imaging means for displaying a contour of a two-dimensional image with a transparent region inside the contour; a light source device for projecting light onto a surface of the liquid photosensitive resin through the transparent region to cure the liquid curable resin; an elevator means for raising and lowering the cured resin; a controlling unit for controlling the elevator means, the imaging means and the light source device to work; wherein, the imaging means is disposed between the vat and the light source device; the elevator means moves with respect to the vat; the controlling unit is electrically connected with the imaging means and the light source device; the light source device emits substantially parallel light.
For more clearly and easily understanding above content of the present invention, the following text will take a preferred embodiment of the present invention with reference to the accompanying drawings for detail description as follows. The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.
The embodiments of the present invention will be described in detail with reference to the accompanying drawings. It is intended that the present invention not be limited to the particular embodiment disclosed, but that the present invention will include all embodiments falling within the scope of the appended claims.
In the present disclosure, the term “area light source” is intended to mean that a light source emits substantially parallel light. In one embodiment of the present disclosure, “area light source” means that an emitter comprises a plurality of light emitting units distributed on a plane uniformly.
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When the stereolithographic apparatus 1000 is assembled, the light source device 100, the imaging means 200 and the container 300 are laminated in this order, which can provide a compact stereolighgaphic apparatus. The imaging means 200 is disposed between the light source device 100 and the container 300. The light emitted by the light source device 100 is projected onto the liquid photosensitive resin 400 in the container 300 through the imaging means 200.
The imaging means 200 is monochrome Thin Film Transistor Liquid Crystal Display (TFT-LCD) or colore TFT-LCD. TFT-LCD has following advantages: high speed, high brightness and high contrast. Alternatively, the imaging means 200 is not limited to this, and the imaging means 200 may be other kinds of LCD, such as Twisted Nematic LCD, Super Twisted Nematic LCD.
The imaging means 200 has a driving unit 220 for driving pixels of the imaging means 200 to display a contour of desired two-dimensional image. A transparent region is presented inside the contour. The light can pass through the transparent region. However, the light cannot pass through the region outside the contour.
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In this embodiment, the light source device 100 further comprises a light shading member 136C (as shown in
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In this embodiment, the light source device 100 further comprises a controller 110 electrically connected with the light emitting units 130 for controlling them to be on or off. The controller 110 can control each light emitting unit 130 to be on or off. With such configuration of the controller 110, the light emitting units 130 corresponding to the contour of the two-dimensional image displayed on the imaging means 200 are on. However, the light emitting units 130 located in a position corresponding to a region outside the contour are off. Thus, on one hand, the stray light can be reduced; on the other hand, the electric power can be saved.
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In this embodiment, the collimator 134 may be a reflector or a lens. For example, the collimator 134 may be a concave mirror or a spherical reflector. Alternatively, the collimator 134 may be a convex lens or a Fresnel lens. However, the collimator 134 is not limited to this; it may be other appropriate elements. By the configuration of collimator, it can effectively prevent the photosensitive resin that should not be cured from curing. In this embodiment, the emitter 132 and collimator 134 may be disposed in the compartment 131 of the frame 120. Alternatively, the collimator 134 may be disposed outside the compartment 131. Moreover, the inner walls of the compartments 131 may serve as collimators for converting divergent light to substantially parallel light, which can effectively solidify the resin and provide a compact apparatus. In this embodiment, one emitter 132 may correspond to one collimator 134. Alternatively, a multiple emitters 132 may correspond to one collimator 134, or, all of the emitters 132 may correspond to one collimator 134.
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A window is formed in the centre of the light shading member 136C. For example, the light shading member 136C may be a fiber reinforced polymer that is capable of absorbing light. The emitter 132C, the reflector 133C, the lens 134C and the light shading member 136C are disposed in the compartment 131. With such configuration, the light emitting unit can effectively convert the divergent light to substantially parallel light for curing the photosensitive resin.
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Each of the light emitting units 130 includes a LED. A wavelength of light emitted by the light emitting unit 130 is ranged from 250 nm to 700 nm. Preferably, the wavelength of the light may be ranged from 350 nm to 500 nm. The light emitting unit 130 may be UV LED, blue LED, green LED, yellow LED, cyan LED, orange LED, red LED or white LED.
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step 101: fill the photosensitive resin 400 into the container 300;
step 102: display the contour of one of the cross-sections on the imaging means 200 with a transparent region inside the contour;
step 103: the light emitting unit 130 emit light through the transparent region to cure the photosensitive resin 400 in the container 300 and convert it into a solid layer corresponding to the cross-section of the object;
step 104: determine all of the cross-sections have been built, if all of the cross-sections have been built, the process is completed; otherwise, execute the next step;
step 105: lift the previous solid layer, refill the liquid photosensitive resin and repeat the steps 102-104 to form the object. When the liquid photosensitive resin 400 in the container 300 has been cured and converted to a solid layer, the elevator member 500 lift the solid layer upward to form a predetermined gap between the solid layer and the remain resin 400. After newly added photosensitive resin filled into the gap, the elevator member 500 moves downward, positioned in a proper position, and then cure the newly added resin and convert it into the next solid layer.
The stereolithographic apparatus may be used to produce various two-dimensional objects or three-dimensional objects. The light system only has the light source device and the imaging means, which has the following advantages: simple position relationship, compact structure, less part, reduced dimension and manufacturing cost. Compared with the laser scanning system or the DLP projector, the cost of the imaging means in the illustrated embodiments is low, and the amount of material in the illustrated embodiments is reduced.
While the present invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the present invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present invention without departing from its scope.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201410137959.X | Apr 2014 | CN | national |
