Wall Smoothness, Feature Accuracy and Resolution in Projected Images via Exposure Levels in Solid Imaging

Abstract

A solid imaging apparatus and method employing levels of exposure varied with gray scale or time or both of digitally light projected image of a cross-section of a three-dimensional object on a solidifiable photopolymer build material. The gray scale levels of exposure of projected pixels permits the polymerization boundaries in projected boundary pixels to be controlled to achieve preserved image features in a three-dimensional object and smooth out rough or uneven edges that would otherwise occur using digital light projectors that are limited by the number of pixels in an image projected over the size of the image. Software is used to control intensity parameters applied to pixels to be illuminated in the image projected in the cross-section being exposed in the image plane.

1 - 15 . (canceled) 
     
     
         16 . An apparatus for forming a three-dimensional object layer-by-layer by solid imaging comprising in combination:
 a. a frame;   b. a radiation transparent carrier moveably mounted to the frame;   c. a radiation source mounted to the frame for projecting an image one cross-section at a time of a three-dimensional object to be built through the radiation transparent carrier;   d. a source of solidifiable photopolymer build material in fluid flow communication with the radiation transparent carrier effective to apply the solidifiable photopolymer build material to the radiation transparent carrier;   e. a support platform moveably mounted to the frame to support the three-dimensional object as it is built layer-by-layer;   f. a controller mounted to the frame effective to control movement of the radiation transparent carrier and the support platform and to control illumination of selected pixels by the radiation source in an image exposure of a cross-section of the three-dimensional object on the solidifiable photopolymer build material;   g. a computer in data flow communication with the controller to receive the digital data relating to the three-dimensional object to be built and convert the digital data into data representative of cross-sections of the three-dimensional object;   
       wherein the radiation source projects an image representative of cross-sectional digital data through the radiation transparent carrier to selectively illuminate pixels in an illumination pattern on an image area exposure and to selectively solidify the photopolymer build material by applying different exposure parameters to different portions of the image area to control the polymerization boundary of the solidifiable photopolymer build material to obtain a high resolution image and a three-dimensional object that has all features properly positioned and smooth walls. 
     
     
         17 . The apparatus according to  claim 16  wherein the radiation source is selected one from the group consisting of a UV radiation source, a visible light source and a combination thereof. 
     
     
         18 . The apparatus according to  claim 17  wherein the radiation source is a digital light projector. 
     
     
         19 . The apparatus according to  claim 16  wherein the radiation transparent carrier is an endless belt. 
     
     
         20 . The apparatus according to  claim 16  wherein the radiation transparent carrier further is a flexible film. 
     
     
         21 . The apparatus according to  claim 16  wherein the radiation transparent carrier is a plate. 
     
     
         22 . The apparatus according to  claim 16  wherein the controller is a microprocessor that selects pixels to be illuminated in the exposure of a cross-section of the three-dimensional object on the solidifiable liquid by use of an algorithm. 
     
     
         23 . The apparatus according to  claim 22  wherein the microprocessor uses software to control light intensity versus gray scale levels across an image projected by the digital light projector onto the solidifiable photopolymer build material in order to optimize the image projection of the three-dimensional object. 
     
     
         24 . The apparatus according to  claim 22  wherein the microprocessor uses software to apply light intensity levels of exposure, illumination pattern width and time of illumination of pixels in the image area as the exposure parameters applied to the image area to position a boundary of a projected boundary pixel of the three-dimensional object in a single exposure. 
     
     
         25 . An apparatus for forming a three-dimensional object layer-by-layer by solid imaging comprising in combination: a. a frame; b. a source of solidifiable photopolymer build material effective to supply the solidifiable photopolymer build material to form a layer of build material to be solidified with an exposed surface; c. a radiation source mounted to the frame for projecting onto the surface of the solidifiable photopolymer build material a cross-section at a time of a three-dimensional object to be built effective to solidify each cross-section of the three-dimensional object; d. a support platform moveably mounted to the frame to support the three-dimensional object as it is built layer-by-layer; e. a controller mounted to the frame effective to control recoating of an exposed layer of the liquid medium with a fresh layer of the solidifiable liquid medium, control movement of the support platform, and to control illumination of selected pixels by the radiation source in an image exposure of a cross-section of the three-dimensional object on the solidifiable liquid medium; f. a computer in data flow communication with the controller to receive three-dimensional digital data in relation to the three-dimensional object to be built and convert the digital data into data representative of cross-sections of the three-dimensional object; and g. software to control light intensity versus gray scale levels across an image projected by the digital light projector onto the solidifiable photopolymer build material in order to optimize the image projection of a three-dimensional object to control the polymerization boundary of the solidifiable photopolymer build material in boundary pixels to obtain a high resolution image and a three-dimensional object that has all features properly positioned and smooth walls. 
     
     
         26 . The apparatus according to  claim 25  wherein the radiation source is selected one from the group consisting of a UV radiation source, a visible light source and a combination thereof. 
     
     
         27 . The apparatus according to  claim 25  wherein the radiation source is a digital light projector. 
     
     
         28 . The apparatus according to  claim 25  further comprising a recoater moveably mounted to the frame for recoating an exposed layer of the photopolymer build material with a fresh layer of the solidifiable photopolymer build material. 
     
     
         29 . The apparatus according to  claim 25  wherein the solidifiable photopolymer build material selected from the group consisting of a solidifiable photopolymer liquid resin formulation, a solidifiable photopolymer paste, a solidifiable photopolymer gel, a solidifiable photopolymer semi-liquid and combinations thereof. 
     
     
         30 . The apparatus according to  claim 25  wherein said software also applies light intensity levels of exposure, illumination pattern width and time of illumination of pixels in the image plane as intensity parameters applied to the image plane medium by controlling the polymerization boundary of a projected boundary pixel of the three-dimensional object in a single exposure in order to optimize the image projection of the three-dimensional object and obtain a three-dimensional object that has all features properly positioned and smooth walls. 
     
     
         31 . The apparatus according  claim 25  wherein the source of solidifiable photopolymer build material being a vat mounted to the frame containing the surface of the solidifiable photopolymer build material onto which the image is projected. 
     
     
         32 . The apparatus according to  claim 25  wherein the solidifiable photopolymer build material is image exposed on a radiation transparent carrier.