# US 2018/0022041 A1 · Layer orientation control for pixel-based additive manufacturing > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0022041 A1 - Document ID: US20180022041A1 - Status: Published application - Kind: A1 - Application number: 15/217,548 - Filed: 2016-07-22 - Published: 2018-01-25 - Earliest claimed: 2016-07-22 - Assignees: General Electric Company - Applicants: General Electric Company - Inventors: Travis Gene Sands; Stephen Michael Deak - Web page: https://patentgrep.com/patent/US20180022041A1 ## CPC - B29C 64/129: characterised by the energy source therefor, e.g. by global irradiation combined with a mask - B29C 64/241: for rotary motion - B29C 64/273: pulsed; frequency modulated - B29C 64/282: of the same type, e.g. using different energy levels - B29C 64/386: Data acquisition or data processing for additive manufacturing - B29C 64/40: Structures for supporting 3D objects during manufacture and intended to be sacrificed after completion thereof - B33Y 10/00: Processes of additive manufacturing - B33Y 30/00: Apparatus for additive manufacturing; Details thereof or accessories therefor - B33Y 50/02: for controlling or regulating additive manufacturing processes - B33Y 80/00: Products made by additive manufacturing - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) - B33Y: ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING ## Abstract A method is provided for making a workpiece in an additive manufacturing process in which a starting material is solidified in a layer by layer fashion, with each layer of the workpiece being solidified using a patterned image of radiant energy configured as a two-dimensional grid array of pixels. The method includes: for each layer of the workpiece, determining a preferred angular orientation of the grid array, relative to the layer; and orienting the patterned image to the preferred angular orientation before solidifying the starting material for that layer. ## Claims ### Claim 1 A method of making a workpiece in an additive manufacturing process in which a starting material is solidified in a layer by layer fashion, with each layer of the workpiece being solidified using a patterned image of radiant energy configured as a two-dimensional grid array of pixels, the method comprising: for each layer of the workpiece, determining a preferred angular orientation of the grid array, relative to the layer; and orienting the patterned image to the preferred angular orientation before solidifying the starting material for that layer. ### Claim 2 (depends on 1) The method of claim 1 wherein each pixel has a quadrilateral shape. ### Claim 3 (depends on 2) The method of claim 2 wherein each pixel has a rectangular shape. ### Claim 4 (depends on 1) The method of claim 1 wherein the preferred angular orientation is selected to align an edge of one or more pixels with an edge of the workpiece. ### Claim 5 (depends on 1) The method of claim 1 wherein the starting material is a photopolymer and the patterned image is projected using ultraviolet light. ### Claim 6 (depends on 1) The method of claim 1 wherein the preferred angular orientation is selected randomly for two or more layers. ### Claim 7 (depends on 1) The method of claim 1 wherein the preferred angular orientation alternates between a nominal angular orientation and an off-nominal angular orientation. ### Claim 8 (depends on 1) The method of claim 1 wherein the preferred angular orientation is determined by an optimization algorithm which minimizes the number or area of pixels crossing an peripheral edge of the workpiece. ### Claim 9 (depends on 1) The method of claim 1 wherein the layers are stacked along a build axis, and the angular orientation of the layers are selected considering surface quality of the workpiece along the build axis. ### Claim 10 A method of making a workpiece, comprising: placing an uncured resin in a vat; positioning a build platform in the resin at a selected location along a first axis, so as to expose a layer of resin; rotating at least one of the build platform and a projector about the first axis, so as to orient the projector at a predetermined angular orientation relative to the exposed layer of resin; and using the projector, selectively curing the layer of resin by projecting a patterned image of radiant energy onto the layer of resin, wherein the patterned image is configured as a grid pattern comprising rows and columns of pixels arrayed along second and third mutually perpendicular axes respectively, wherein the second and third axes are perpendicular to the first axis, and wherein the grid pattern is aligned at the predetermined angular orientation. ### Claim 11 (depends on 10) The method of claim 10 wherein each pixel has a quadrilateral shape. ### Claim 12 (depends on 10) The method of claim 10 wherein the predetermined angular orientation is selected to align an edge of one or more of the pixels with an edge of a workpiece. ### Claim 13 (depends on 10) The method of claim 10 further comprising repeating in a cycle the steps of positioning, rotating, and projecting to build up the workpiece in a layer-by layer fashion. ### Claim 14 (depends on 13) The method of claim 13 wherein the predetermined angular orientation is selected randomly for two or more layers. ### Claim 15 (depends on 13) The method of claim 13 wherein the predetermined angular orientation alternates between a nominal angular orientation and an off-nominal angular orientation. ### Claim 16 (depends on 13) The method of claim 13 wherein the preferred angular orientation is determined by an optimization algorithm which minimizes the number or area of pixels crossing an peripheral edge of the workpiece. ### Claim 17 (depends on 13) The method of claim 13 wherein the angular orientation of the layers are selected considering surface quality of the workpiece along the first axis. ### Claim 18 An apparatus for making a workpiece, comprising: a vat configured to contain a liquid resin; a platform movable along a build axis within the vat; a projector operable to project a patterned image of radiant energy comprising rows and columns of pixels; and means for changing a relative angular orientation of the platform and the projector about the build axis. ### Claim 19 (depends on 18) The apparatus of claim 18 wherein the projector comprises: a radiant energy source; and an image forming apparatus. ### Claim 20 (depends on 19) The apparatus of claim 19 wherein the radiant energy source comprises an ultraviolet flash lamp.