Patent ID: 6051179
Filing Date: 2000-04-18
Classification: B29C,B33Y

Abstract:
An improved three-dimensional object producing apparatus of the type for irradiating a liquid surface of a vat of liquid photo-curable resin to form a succession of cured resin layers corresponding to successive cross-sectional laminae of a three-dimensional object, and incrementally lowering the cured resin layers below the liquid surface as they are formed to build up a three-dimensional copy of the object, wherein the improvement comprises:a radiant energy source of a wide beam of radiant energy of suitable intensity and wavelength for curing a layer of the photo-curable resin;a spatial light modulator (SLM) having an array of pixel elements which are individually controllable, for modulating the radiant energy beam projected from the radiant energy source on a pixel-by-pixel basis, to form a series of time sequential images of the cross-sectional laminae of the object;optical means for focusing each image formed by the SLM, one at a time, onto successive layers of photo-curable resin for predetermined exposure times to thereby form stacked laminae of cured resin, each lamina of cured resin being in the shape of a different one of the cross-sectional laminae; andmeans for positioning each lamina of cured resin after it is formed by the SLM below the liquid surface corresponding to the thickness of one cross-sectional lamina of the three-dimensional object before the projection of a new image by the SLM to thereby flow a layer of photo-curable liquid resin to cover the lamina of cured resin;wherein the SLM, the means for lowering, and the optical means operate repeatedly and sequentially until a complete copy of the object is thereby produced; andwherein certain pixels' states are repeatedly toggled ON and OFF during the exposure so that during a given exposure period the pixels are ON a predetermined percentage of the time and OFF the remaining percentage of the time.