Patent Publication Number: US-2023138135-A1

Title: Scanned DLP with Pixel Drift

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application 62/263,042, filed on Oct. 26, 2021. The disclosure of this prior application is considered part of the disclosure of this application and is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     This disclosure generally relates to an additive fabrication system that uses a digital light processing (DLP) projector, and more particularly relates to an additive fabrication system that uses a scanned DLP projector with pixel drift. 
     BACKGROUND 
     Additive fabrication, e.g., three-dimensional (3D) printing, provides techniques for fabricating objects, typically by causing portions of a building material to solidify at specific locations. Additive fabrication techniques may include stereolithography, selective or fused deposition modeling, direct composite manufacturing, laminated object manufacturing, selective phase area deposition, multi-phase jet solidification, ballistic particle manufacturing, particle deposition, laser sintering or combinations thereof. Many additive fabrication techniques build parts by forming successive layers, which are typically cross-sections of the desired object. Typically each layer is formed such that it adheres to either a previously formed layer or a build surface upon which the object is built. 
     In one approach to additive fabrication, known as stereolithography, solid objects are created by successively forming thin layers of a curable polymer resin, typically first onto a build surface and then one on top of another. Exposure to actinic radiation cures a thin layer of liquid resin, which causes it to harden and adhere to previously cured layers on the bottom surface of the build surface. 
     SUMMARY 
     An aspect of the disclosure provides a curing system for an additive fabrication system. The curing system includes a basin configured to receive a photopolymer resin, an ultraviolet light source, and a translating device. The ultraviolet light source is configured to selectively emit ultraviolet light. The ultraviolet light defines a pixelated array that illuminates at least a portion of the photopolymer resin. The pixelated array includes a first array axis and a second array axis oriented perpendicular to the first array axis. The translating device is configured to translate the pixelated array along a translation axis at an oblique angle relative to the first array axis. 
     Aspects of the disclosure may include one or more of the following optional features. In some implementations the ultraviolet light source includes a digital light processing (DLP) projector. In some implementations the ultraviolet light source includes a liquid crystal display (LCD). The ultraviolet light source may include a light-emitting diode (LED) array. The ultraviolet light source may include an organic light-emitting diode (OLED) array. The ultraviolet light source may include a micro-LED array. In some examples, a reflector device reflects the ultraviolet light emitted from the ultraviolet light source at the photopolymer resin. In those examples, the reflector device is configured to establish the pixelated array. In further examples, the reflector device includes a digital micromirror device (DMD). In some implementations, the pixelated array represents at least a portion of a build layer of a fabricated component. 
     In some embodiments, the translating device is configured to translate the pixelated array along the translation axis between a first position and a second position spaced from the first position. In further embodiments, the pixelated array is in a first configuration at the first position and the pixelated array is in a second configuration different from the first configuration at the second position. In even further embodiments, as the translating device translates the pixelated array between the first position and the second position, the ultraviolet light source does not emit ultraviolet light. In other even further embodiments, as the translating device translates the pixelated array between the first position and the second position, the ultraviolet light source emits ultraviolet light. In additional even further embodiments, as the translating device translates the pixelated array between the first position and the second position, the pixelated array transforms between the first configuration and the second configuration. In further embodiments, the translating device translates the pixelated array at a rate configured to allow at least a portion of the photopolymer resin illuminated by the pixelated array to cure. 
     Another aspect of the disclosure provides an additive fabrication system. The additive fabrication system includes a dispensing system, a base supporting a basin, a build platform, and a curing system. The basin is configured to receive a photopolymer resin from the dispensing system. The build platform is operable to traverse a vertical direction between an initial position adjacent to a bottom surface of the basin and a finished position spaced apart from the bottom surface of the basin. The curing system is housed within the base and configured to transmit actinic radiation into the basin to incrementally cure layers of the photopolymer resin onto the build platform to fabricate a component. The curing system includes an ultraviolet light source and a translating device. The ultraviolet light source is configured to selectively emit ultraviolet light. The ultraviolet light defines a pixelated array that illuminates at least a portion of the photopolymer resin. The pixelated array includes a first array axis and a second array axis oriented perpendicular to the first array axis. The translating device is configured to translate the pixelated array along a translation axis at an oblique angle relative to the first array axis. 
     This aspect of the disclosure may include one or more of the following optional features. In some examples, the ultraviolet light source includes a digital light processing (DLP) projector. In some further examples, the ultraviolet light source includes a liquid crystal display (LCD). The ultraviolet light source may include a light-emitting diode (LED) array. The ultraviolet light source may include an organic light-emitting diode (OLED) array. The ultraviolet light source may include a micro-LED array. In some embodiments, a reflector device reflects the ultraviolet light emitted from the ultraviolet light source at the photopolymer resin. In those embodiments, the reflector device is configured to establish the pixelated array. In further embodiments, the reflector device includes a digital micromirror device (DMD). In some implementations, the pixelated array represents at least a portion of a build layer of a fabricated component. 
     In some embodiments, the translating device is configured to translate the pixelated array along the translation axis between a first position and a second position spaced from the first position. In further embodiments, the pixelated array is in a first configuration at the first position and the pixelated array is in a second configuration different from the first configuration at the second position. In even further embodiments, as the translating device translates the pixelated array between the first position and the second position, the ultraviolet light source does not emit ultraviolet light. In other even further embodiments, as the translating device translates the pixelated array between the first position and the second position, the ultraviolet light source emits ultraviolet light. In additional even further embodiments, as the translating device translates the pixelated array between the first position and the second position, the pixelated array transforms between the first configuration and the second configuration. In further embodiments, the translating device translates the pixelated array at a rate configured to allow at least a portion of the photopolymer resin illuminated by the pixelated array to cure. 
     Another aspect of the disclosure provides a method for curing a photopolymer resin using a curing system that includes an ultraviolet light source. The method includes providing a curing system. The curing system includes a basin containing a photopolymer resin, an ultraviolet light source configured to emit ultraviolet light, and a translating device. The method further includes emitting ultraviolet light from the ultraviolet light source to cure at least a first portion of the photopolymer resin. The ultraviolet light defines a pixelated array that includes a first array axis and a second array axis oriented perpendicular to the first array axis. The method further includes translating, via the translating device, the pixelated array along a translation axis at an oblique angle relative to the first array axis to cure at least a second portion of the photopolymer resin different from the first portion. 
     This aspect of the disclosure may include one or more of the following optional features. In some examples the ultraviolet light source includes a digital light processing (DLP) projector. In some further examples, the ultraviolet light source includes a liquid crystal display (LCD). The ultraviolet light source may include a light-emitting diode (LED) array. The ultraviolet light source may include an organic light-emitting diode (OLED) array. The ultraviolet light source may include a micro-LED array. In some implementations, emitting the ultraviolet light includes reflecting the ultraviolet light emitted from the ultraviolet light source at the photopolymer resin by a reflector device configured to establish the pixelated array. In further implementations, the reflector device includes a digital micromirror device (DMD). In some embodiments, the pixelated array represents at least a portion of a build layer of a fabricated component. 
     In some examples, translating the pixelated array along the translation axis includes translating the pixelated array between a first position and a second position spaced from the first position. In further examples, the pixelated array is in a first configuration at the first position and the pixelated array is in a second configuration different from the first configuration at the second position. In even further examples, as the translating device translates the pixelated array between the first position and the second position, the ultraviolet light source does not emit ultraviolet light. In other even further examples, as the translating device translates the pixelated array between the first position and the second position, the ultraviolet light source emits ultraviolet light. In additional other even further examples, as the translating device translates the pixelated array between the first position and the second position, the pixelated array transforms between the first configuration and the second configuration. In further examples, translating the pixelated array includes translating the pixelated array at a rate configured to allow at least a portion of the photopolymer resin illuminated by the pixelated array to cure. 
     The details of one or more implementations of the disclosure are set forth in the accompanying drawings and the description below. Other aspects, features, and advantages will be apparent from the description and drawings, and from the claims. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG.  1 A  shows a perspective view of an example additive fabrication system, where the system is arranged in an initial configuration. 
         FIG.  1 B  shows a perspective view of an example additive fabrication system, where the system is arranged in a fabricating configuration. 
         FIG.  1 C  shows a perspective view of an example additive fabrication system, where the system is arranged in a finished configuration. 
         FIG.  2    shows a perspective view of an example of the additive fabrication system of  FIG.  1 A . 
         FIG.  3    shows a plan view of a curing system projecting light onto a curing plane. 
         FIGS.  4 A and  4 B  show images generated using the same size pixels, where  FIG.  4 A  was generated without pixel drift and  FIG.  4 B  was generated with pixel drift. 
         FIG.  5    shows a plan view of a pixelated array tilted relative to a translation axis of movement. 
         FIGS.  6 A- 6 C  show plan views of pixelated arrays translated along respective translation axes of movement, where the pixelated arrays each have square pixels and are tilted relative to the translation axis by a different angle. 
         FIGS.  7 A and  7 B  show plan views of pixelated arrays translated along respective translation axes of movement, where the pixelated arrays each have rectangular pixels and are tilted relative to the translation axis by a different angle. 
         FIGS.  8 A and  8 B  show plan views of pixelated arrays having different drift numbers. 
         FIG.  9    shows a flow diagram for a scanned exposure scanning strategy of curing a layer of a component fabricated by an additive fabrication device having a curing system according to the present disclosure. 
         FIG.  10    shows a flow diagram for a quasi-tile exposure scanning strategy of curing a layer of a component fabricated by an additive fabrication device having a curing system according to the present disclosure. 
         FIG.  11    shows a flow diagram for a single quasi-tile exposure scanning strategy of curing a layer of a component fabricated by an additive fabrication device having a curing system according to the present disclosure. 
         FIG.  12    shows the printable area provided by a stationary pixelated array. 
         FIG.  13    shows the printable area provided by a pixelated array translated along a translation axis that is at an oblique angle relative to the pixelated array. 
         FIGS.  14  and  15    are graphs showing the print time of a curing system utilizing different scanning strategies for liquid photopolymer resins having different fluence values. 
         FIG.  16    is a plan view of a curing system having a single light source. 
         FIG.  17    is a plan view of a curing system having two light sources. 
     
    
    
     Like reference symbols in the various drawings indicate like elements. 
     DETAILED DESCRIPTION 
     The present disclosure relates to a curing system for an additive fabrication device (i.e., a three-dimensional (3D) printer) that incorporates a digital light processing (DLP) projector configured to emit light to transform a liquid photopolymer resin into a solid layer of a fabricated component. As will be discussed below, DLP projectors emit light at a wavelength configured to cure the liquid photopolymer resin and emit such light in a pixelated array corresponding to at least a portion the layer of the fabricated component. Because the DLP projectors emit light in a pixelated array, the resolution of the fabricated components are subject to the tolerance constraints of the pixelated array and thus may suffer from voxelization. In other words, surfaces of fabricated components formed using a traditional additive fabrication device having a DLP projector that are intended to be smooth, curved surfaces may instead be stepped surfaces (i.e., a series of small, square faces offset from one another). Improvements in resolution for a conventional system utilizing a DLP projector may achieve improvements in resolution of the fabricated component by moving the pixelated array along X and Y axes while curing a given layer of the resin. Unlike conventional additive fabrication systems, the curing system of the present disclosure achieves improvements in resolution of a fabricated component by moving a pixelated array of light projected from a DLP projector along a single axis while curing a given layer of liquid photopolymer resin. Thus, the present disclosure provides a curing system for an additive fabrication device that provides for enhanced resolution of fabricated components formed thereby and, because the curing system achieves the enhanced resolution with movement along only a single axis of a pixelated array formed from light emitted by a DLP projector, the curing system of the present disclosure provides for an additive fabrication device with simpler mechanical and software needs. 
     Referring to  FIGS.  1 A- 1 C , an additive fabrication device  100 , such as a stereolithographic printer, includes a base  110  and a dispensing system  120  coupled to the base  110 . The base  110  supports a fluid basin  130  configured to receive a photopolymer resin R ( FIG.  3   ) from the dispensing system  120 . The printer  100  further includes a build platform  140  positioned above the fluid basin  130  and operable to traverse a vertical axis (e.g., z-axis) between an initial position ( FIG.  1 A ) adjacent to a bottom surface  132  of the fluid basin  130  and a finished position ( FIG.  1 C ) spaced apart from the bottom surface  132  of the fluid basin  130 . 
     The base  110  of the printer  100  may house various mechanical, optical, electrical, and electronic components operable to fabricate objects using the device. In the illustrated example, the base  110  includes a computing system  150  including data processing hardware  152  and memory hardware  154 . The data processing hardware  152  is configured to execute instructions stored in the memory hardware  154  to perform computing tasks related to activities (e.g., movement and/or printing based activities) for the printer  100 . Generally speaking, the computing system  150  refers to one or more locations of data processing hardware  152  and/or memory hardware  154 . For example, the computing system  150  may be located locally on the printer  100  or as part of a remote system (e.g., a remote computer/server or a cloud-based environment). 
     The base  110  may further include a control panel  160  connected to the computing system  150 . The control panel  160  includes a display  162  configured to display operational information associated with the printer  100  and may further include an input device  164 , such as a keypad or selection button, for receiving commands from a user. In some examples, the display is a touch-sensitive display providing a graphical user interface configured to receive the user commands from the user in addition to, or in lieu of, the input device  164 . 
     The base  110  houses a curing system  170  configured to transmit actinic radiation into the resin basin  130  to incrementally cure layers of the photopolymer resin contained within the basin  130 . The curing system  170  may include a projector or other radiation source configure to emit light at a wavelength suitable to cure the photopolymer resin R within the basin. Thus, different light sources may be selected depending on the desired photopolymer resin R to be used for fabricating a component C. In the present disclosure, the curing system  170  includes a DLP projector for curing the photopolymer resin within the basin  130 . 
     As shown, the basin  130  is disposed atop the base  110  adjacent to the curing system  170  and is configured to receive a supply of the resin R from the dispensing system  120 . The dispensing system  120  may include an internal reservoir  124  providing an enclosed space for storing the resin until the resin is needed in the basin  130 . The dispensing system  120  further include a dispensing nozzle  122  in communication with the basin  130  to selectively supply the resin R from the internal reservoir  124  to the basin  130 . 
     The build platform  140  may be movable along a vertical track or rail  142  (oriented along the z-axis direction, as shown in  FIGS.  1 A- 1 C ) such that base-facing build surface  144  of the build platform  140  is positionable at a target distance D 1  along the z-axis from a bottom surface  132  of the basin  130 . The target distance D 1  may be selected based on a desired thickness of a layer of solid material to be produced on the build surface  144  of the build platform  140  or onto a previously formed layer of the object being fabricated. In some implementations, the build platform  140  is removable from the printer  100 . For instance, the build platform  140  may be attached to the rail  142  by an arm  146  (e.g., pressure fit or fastened onto) and may be selectively removed from the printer  100  so that a fabricated component C attached to the build surface  144  can be removed. 
     In the example of  FIGS.  1 A- 1 C , the bottom surface  132  of the basin  130  may be light-transmissible (e.g., transparent, translucent) to actinic radiation that is generated by the curing system  170  located within the base  110 , such that liquid photopolymer resin located between the bottom surface  132  of the basin  130  and the build surface  144  of the build platform  140  or an object being fabricated thereon, may be exposed to the radiation. Upon exposure to such actinic radiation, the liquid photopolymer may undergo a chemical reaction, sometimes referred to as “curing,” that substantially solidifies and attaches the exposed resin to the build surface  144  of the build platform  140  or to a bottom surface of an object being fabricated thereon. 
     Following the curing of a layer of the fabrication material, the build platform  140  may incrementally advance upward along the rail  142  in order to reposition the build platform  140  for the formation of a new layer and/or to impose separation forces upon any bond with the bottom surface  132  of basin  130 . In addition, the basin  130  is mounted onto the support base such that the printer  100  may move the basin  130  along a horizontal axis of motion (e.g., x-axis), the motion thereby advantageously introducing additional separation forces in at least some cases. A wiper  134  is additionally provided, capable of motion along the horizontal axis of motion and which may be removably or otherwise mounted onto the base  110  or the fluid basin  130 . 
     With continued reference to  FIGS.  1 A- 1 C , the printer  100  is shown at different stages of the fabrication process. For example, at  FIG.  1 A , the printer is shown in an initial state prior to dispensing the resin R into the basin  130  from the reservoir  124  of the dispensing system  120 . Upon receipt of fabrication instructions, the printer  100  positions the build surface  144  of the build platform  140  at an initial distance D 1  from the bottom surface  132  of the basin  130  corresponding to a thickness of the first layer of resin R to be cured. The curing system  170  then emits an actinic radiation profile (i.e., an image) corresponding to the profile of the current layer of the component C to cure the current layer. Upon curing of the current layer, the build platform  140  incrementally advances upward to the next build position. The distance of each advancement increment corresponds to a thickness of the next layer to be fabricated. The curing system  170  then projects the profile of the component layer corresponding to the new position. The new component layer is cured on a bottom surface of the previous component layer. The curing and advancing steps repeat until the build platform  140  reaches the final position ( FIG.  1 C ) corresponding to the finished component C. 
     Referring now to  FIG.  3   , the curing system  170  includes a light source  172  that emits the actinic radiation profile or ultraviolet light as a pixelated array  180  of light corresponding to at least a portion of a layer of the component C. The light source  172  may include any suitable light source configured to emit the pixelated array  180 . For example, the light source  172  may include one or more, such as an array including, a light-emitting diode (LED), an organic light-emitting diode (OLED), a micro-LED, a liquid crystal display (LCD), or any other suitable light emitting device. In the illustrated embodiment, the light source  172  includes the DLP projector  174  that emits light at a wavelength suitable to cure the liquid photopolymer resin. The DLP projector  174  may include the one or more LEDs, OLEDs, micro-LEDs, or the LCD. Light emitted by the DLP projector  174  may shine directly on the target area  182  (the build platform or the previously cured layer of the component) to cure the resin or the light may be reflected onto the target area  182  via a digital micromirror device (DMD)  176 , where the DMD  176  is responsible for transforming the light emitted by the DLP projector  174  into the pixelated array  180 . The DMD  176  includes a series of light reflecting and light absorbing components arranged in a matrix on a semiconductor chip. For example, the DMD  176  may include a series of mirrors and heat sinks. Selectively toggling a portion of the semiconductor to expose individual ones of the mirrors and heat sinks results in the reflection of the desired pixelated array  180 . It should be understood that the light source  172  of the curing system  170  may emit a plurality of pixelated arrays, such as from a plurality of DLP projectors and/or DMDs, but for the sake of clarity in providing the present disclosure, unless otherwise noted, the illustrated embodiment cures layers of the finished component C via a single pixelated array  180 . 
     As described above, curing a layer of the finished component C involves emitting light through the liquid photopolymer resin R onto the target area  182 . Emitting the light in the form of the pixelated array  180  allows the curing system  170  to emit uniform light across and cure a larger portion (and in some instances, the entirety) of a layer of the finished component C at a given time. This results in faster and more uniform curing of the finished component C. However, and as also described above, curing the resin via the pixelated array  180  may also result in voxelization or other losses in resolution of the finished component C. Because the pixelated array  180  is an array or matrix of individual pixels  181   a , the edges of a layer cured via the pixelated array  180  are dictated by the locations of activated pixels (i.e., pixels where light is reflected or transmitted from the DLP projector  174 ) and deactivated pixels (i.e., pixels where light is not reflected or transmitted from the DLP projector  174 ). Thus, the resolution of a system that cures a layer of resin via a stationary pixelated array are defined by the length and width of individual pixels. For example, as shown in  FIG.  4 A , an image generated by a conventional pixelated array has comparably lower resolution than an image generated by a pixelated array according to the present disclosure ( FIG.  4 B ). Both images were generated using a pixelated array having the same size pixels. 
     In reference to  FIG.  3   , to improve the resolution provided by the DLP projector  174  (i.e., improve the tolerance capabilities of the curing system  170 ), curing a layer of the finished component C may further include translating the pixelated array  180  along a translation axis A T . The translation axis A T  is depicted as the X axis in  FIG.  3   , with a projection axis A P  depicted as the Z axis. The projection axis A P  is defined by the direction in which the pixelated array  180  is reflected or transmitted to the target area  182 . The pixelated array  180  may be directed at the target area  182  directly from the DLP projector  174  or the pixelated array  180  may be directed at the cure plane via the DMD  176  or any suitable light source. In other words, the DLP projector  174  may project the pixelated array  180  onto the target area  182  directly or the pixelated array  180  may be reflected onto the target area  182  from the DMD  176 . Furthermore, the projection axis A P  is depicted as normal to the target area  182 , but may be at any suitable oblique angle relative to the target area  182 . For example, the pixelated array  180  may be transmitted onto the target area  182  at an oblique angle relative to the target area  182  and the curing system  170  may correct for any image distortion of the pixelated array  180 , such as via software correction of the image of the layer being cured or adjustment of the pixels  181   a  of the pixelated array  180 . Thus, the curing system  170  may transmit the pixelated array  180  to the target area  182  in any suitable way that provides a high resolution image. 
     Translating the pixelated array  180  along the translation axis A T  allows for the light source to cover a larger target area and therefore cure larger layers of the finished component C than a conventional stationary curing system. Translating the pixelated array  180  along the translation axis A T  may also allow for the curing system  170  to improve the resolution of the finished component C along a single axis. In other words, moving the pixelated array  180  along the translation axis A T  allows for a reduction in resolution of the curing system  170  along the translation axis A T . For example, the curing system  170  may configured to translate the pixelated array  180  along the translation axis A T  at a continuous rate or at increments that are less than the width of a pixel  181   a  of the pixelated array  180 . Therefore, moving the pixelated array  180  along the translation axis A T  by a distance that is a fraction of a pixel  181   a  allows the curing system  170  to establish edges of a layer of the finished component C in increments that are less than the width of the pixel  181   a . In other words, the positions of pixels  181   a  as the pixelated array  180  is translated may overlap incrementally to provide for improved resolution. 
     A translating device or system  184  translates the pixelated array  180  relative to the target area  182 . Optionally, the translating device  184  may translate the target area  182  relative to a stationary light source  172  to achieve the translation of the pixelated array  180  along the translation axis A T . In the illustrated embodiment, the translating device  184  moves the light source  172  to translate the pixelated array  180  along the translation axis A T . For example, the translating device  184  may translate the pixelated array  180  via movement of the DLP projector  174  emitting the light. In other embodiments, the pixelated array  180  may be translated along the translation axis A T  via movement (e.g., rotation) of the DMD  176  reflecting the light from the DLP projector  174 , a combination of movement of the DLP projector  174  and DMD  176 , and/or some other type of mechanical movement of the curing system  170  that results in translation of the pixelated array  180  along the translation axis A T . The translating device  184  may include any sort of device suitable for moving components of the curing system  170 , such as a stepper motor. 
     As shown in  FIG.  5   , the pixelated array  180  may be tilted relative to the translation axis A T  (i.e., rotated slightly about the projection axis A P ) so that, when the pixelated array  180  is translated along the translation axis A T , the translation of the pixelated array  180  improves the resolution of the curing system  170  along the translation axis A T  and the tilt or rotation of the pixelated array  180  improves the resolution of the curing system  170  along a direction perpendicular to the translation axis A T  (e.g., the Y axis). In other words, tilting or rotating the pixelated array  180  relative to the translation axis A T  causes the pixels  181   a  to overlap incrementally across the translation axis A T  (Y direction) as well as along the translation axis A T  (X direction) when the pixelated array  180  is translated. 
     The pixelated array  180  is tilted relative to the translation axis A T  by a translation angle θ. For example, the pixelated array  180  may be tilted by a translation angle θ up to 45 degrees relative to the translation axis A T . Thus, full sub-pixel resolution (where tolerances of the pixelated array are less than a dimension of a given pixel in both axes of direction) may be achieved while only translating the pixelated array in a single direction. As will be further described below, the sub-pixel resolution along the translation axis A T  is dictated by the movement of the pixelated array  180  along the translation axis A T  in sub-pixel increments. In other words, pixels  181   a  of the pixelated array  180  may be positioned at locations that overlap with previous pixel positions along the translation axis A T  as the pixelated array  180  translates. Sub-pixel resolution across the translation axis A T  is achieved by tilting the pixelated array  180  by the translation angle θ, which results in incremental cross-axis progression in pixel alignment. In other words, pixels  181   a  of the pixelated array  180  may be positioned at locations that overlap with previous pixel positions across the translation axis A T  as the pixelated array  180  translates. 
       FIG.  6 A  depicts a low tilt pixelated array  180  tilted relative to the translation axis A T  by a translation angle θ of five degrees. As shown, the pixelated array  180  is translated along the translation axis A T  in increments that are less than the width of a pixel  181   a  so that, with the pixelated array  180  positioned at or between the incremental positions, the individual pixels  181   a  may be selectively activated or deactivated to cure resin at a position corresponding to the position of the pixel  181   a . Thus, the resolution of layers of a component cured via such a pixelated array  180  translated along the translation axis A T  may correspond to the differences in position (i.e., the overlap) between pixels  181   a  when the pixelated array  180  is incrementally translated. Similarly,  FIG.  6 B  depicts a medium tilt pixelated array  180  tilted relative to the translation axis A T  by a translation angle θ of 15 degrees and  FIG.  6 C  depicts a full tilt pixelated array  180  tilted relative to the translation axis A T  by a translation angle θ of 45 degrees. 
       FIGS.  6 A- 6 C  depict pixelated arrays  180  with square pixels  181   a .  FIGS.  7 A and  7 B  depict pixelated arrays  180  with rectangular pixels  181   b , with  FIG.  7 A  depicting a low tilt pixelated array  180  tilted relative to the translation axis AT by 5 degrees and  FIG.  7 B  depicting a medium tilt pixelated array  180  tilted relative to the translation axis AT by 15 degrees. Elongation of the pixels  181   b  relative to the translation axis A T  may provide for a more symmetrical overlap of the pixels  181   b  as the pixelated array  180  is translated. 
     The translation angle θ and dimensions of the pixels of the pixelated array  180  provide a drift number N of the pixelated array  180 . The drift number N is the number of pixels  181   a ,  181   b  approximately perpendicular to the translation axis A T  over which a lateral translation of one pixel  181   a ,  181   b  occurs approximately perpendicular to the translation axis A T . In other words, as the pixelated array  180  translates along the translation axis A T , individual pixels  181   a  maintain a lateral position relative to the translation axis A T , with lateral positions of the pixels  181   a  repeating incrementally in a pattern. The number of pixels  181   a  with different lateral positions between repeating lateral position is the drift number N. For example,  FIG.  8 A  depicts a pixelated array  180  with a drift number N of eight and  FIG.  8 B  depicts a pixelated array  180  with a drift number N of five. For square pixels  181   a , the drift number N is equal to 1/tan(θ). Thus, the lower the translation angle θ, the higher the drift number N of the pixelated array  180 . A higher drift number N results in higher resolution across the translation axis A T  because each pixel  181   a  moves laterally to a lower degree relative to its longitudinal translation. However, a higher drift number N also results in a longer drift cycle, which is the distance between repeating lateral positions of pixels  181   a  (i.e., the distance the pixelated array  180  must travel for lateral positions of pixels  181   a  to repeat). One drift cycle corresponds to a travel distance along the translation axis A T  equal to pixel pitch/sin(θ), where the pixel pitch is the distance between the center of each pixel  181   a  (i.e., a dimension of a square pixel). 
     The pixelated array  180  may be tilted relative to the translation axis A T  in any suitable manner. For example, a component of the light source  172 , such as the DLP projector  174  or the DMD  176  may be rotated so as to reflect a pixelated array  180  that is rotated relative to the translation axis A T . Optionally, the image to be projected may be rotated by software so that the resulting pixelated array  180  is rotated relative to the intended image to be projected. The curing system  170  may be configured so that the pixelated array  180  is rotated a fixed amount (such as by having a DMD  176  that is permanently rotated relative to the translation axis AT) or the curing system  170  may be configured to rotate the pixelated array  180  according to a desired resolution of the finished component C, where the translation angle θ is adjustable, such as via a user input or constraint of the image to be projected. For example, the computing system  150  may be configured to receive a user input indicating a desired resolution and rotate the pixelated array  180  appropriately to achieve the desired resolution. The computing system  150  may also be configured to apply a non-uniform drift angle (i.e., rotate portions of the pixelated array  180  by different translation angles θ) such as to correct for image distortion. 
     If there is some error in the translation angle θ of the pixelated array  180  that will lead to an XY placement error between the start and end of a drift cycle. Here, the error will occur perpendicular to the translation axis A T . The magnitude of placement error per drift cycle per degree of misalignment is greater for pixelated arrays with larger pixel pitch. It should be understood that a one degree rotational misalignment is large and that curing systems  170  according to the present disclosure may be properly rotated within a fraction of a degree. A multipoint calibration method or system may correct for rotational misalignment, such as via software in communication with the curing system  170 , that may determine rotational misalignment, such as during a calibration process, responsive to user input, or based on sensed measurements of finished components C during the printing process. 
     As described above, translation of the pixelated array  180  along the translation axis A T  and rotation of the pixelated array  180  relative to the translation axis A T  (i.e., about the projection axis A P ) by a translation angle θ provides improvements in resolution of the cured layer of the finished component C in both X and Y axes. Translation of the pixelated array  180  may be enabled via the translation device or system  184  that causes movement of the DLP projector  174 , movement of the DMD  176 , coordinated movement of both the DLP projector  174  and DMD  176 , movement of the target area  182 , or translation of the pixelated array  180  in any other suitable fashion. Thus, the pixelated array  180  emitted by the curing system  170  onto the target area  182  at any given position along the translation axis AT represents a portion of the cured layer. As the liquid photopolymer resin R is exposed to the light emitted by the curing system  170 , the resin R cures at positions corresponding to the activated pixels  181  of the pixelated array  180 . To achieve the desired resolution of the cured layer, the pixels  181  are selectively activated or deactivated as the pixelated array  180  translates along the translation axis A T  so that the resin at given positions of the target area  182  receive the requisite amount of light to cure. In other words, the pixelated array  180  is translated or scanned across the target area  182 , such as at least between a first position and a second position along the translation axis A T , and the pixelated array  180  is adjusted or updated at the individual pixel level responsive to or during the movement of the pixelated array  180 . 
     The pixelated array  180  may be adjusted or updated according to a scanning method, where the scanning method controls how the pixels  181   a  are selectively activated or deactivated as the pixelated array  180  is translated along the translation axis A T . For example, the pixelated array  180  may be translated along the translation axis A T  between at least a first position and a second position, where the first position and the second position may be distanced relative to one another along the translation axis A T  according to the layer of the finished component C being cured by the curing system  170 . The distance between the first position and the second position is configured so that the pixelated array  180  at the first position overlaps the pixelated array  180  at the second position by at least a fraction of a pixel width. For example, the scanning method may result in a pixelated array  180  at the first position overlapping a pixelated array  180  at the second position by only a fraction of a pixel width or the second position may be only a fraction of a pixel width away from the first position. 
     As will be further discussed below, the scanning method may adjust a configuration of the pixelated array  180  at given intervals or increments of movement of the pixelated array  180  or the scanning method may adjust the configuration of the pixelated array  180  continuously as the pixelated array  180  is scanned along the translation axis A T . A scanning method where the configuration of the pixelated array  180  is adjusted continuously as the pixelated array  180  is translated along the translation axis AT may be referred to as a scanned exposure scanning method. A scanning method where a first configuration of the pixelated array  180  is displayed at a first position and an adjusted second configuration of the pixelated array  180  is displayed at a second position a distance away from the first position, with no light emitted at the target area between the exposure at the first position and the exposure at the second position, may be referred to as a quasi-tile exposure scanning method. 
     During a scanned exposure scanning method, the target area  182  is exposed to light emitted by the DLP projector  174  continuously as the pixelated array  180  is translated along the translation axis A T  between a start and an end position at a continuous velocity. As mentioned above, for a given portion of the liquid photopolymer resin R to cure (i.e., for a pixel  181   a  of the pixelated array  180  to cure a portion of the layer), the portion is exposed to light for at least a threshold amount of time. Therefore, the pixelated array  180  is held substantially stable or motionless at the start and end positions and the velocity is selected so that the pixelated array  180  exposes desired portions of the resin R for at least the threshold amount of time as the pixelated array  180  is translated. The pixelated array  180  is not adjusted between configurations when the pixelated array  180  is at the start and end positions. However, it should be understood that at the start and end positions, the pixelated array  180  is translated along the translation axis A T  a threshold amount to provide the improved resolution at the start and end positions. Individual pixels  181   a  of the pixelated array  180  are adjusted at a rate according to the velocity and exposure time of portions of the layer being cured. Thus, during the scanned exposure scanning method, the pixelated array  180  is translated along the translation axis A T  between a first position and a second position (where the first and second positions are respectively a start position and an end position), where the DLP projector  174  continuously emits light while the pixelated array  180  is translated and the pixelated array  180  is adjusted between a first configuration (i.e., a starting configuration) and a second configuration (i.e., an ending configuration), with any number of intermediate configurations between, as the pixelated array  180  is translated between the first and second positions. 
       FIG.  9    depicts an example scanned exposure scanning method  300 . At step  302 , the light source  172  transmits the pixelated array  180  to the target area  182  at a first or start position, with the pixelated array  180  in a first or starting configuration. Here, the pixelated array  180  is rotated at an oblique angle about the projection axis A P  relative to the translation axis A T . At step  304 , the curing system  170  translates the pixelated array  180  along the translation axis A T  a threshold distance to achieve the improved resolution at the start position. The curing system  170  transmits the pixelated array  180  in the starting configuration for at least a threshold amount of time for a portion of the target area  182  to cure responsive to the emitted light. At step  306 , the curing system  170  translates the pixelated array  180  along the translation axis A T  toward an end position. At step  308 , the curing system  170  adjusts the configuration of the pixelated array  180  as the pixelated array  180  translates toward the end position, translating and adjusting the pixelated array  180  at a rate appropriate for portions of the target area  182  to cure. As necessary, at step  309 , the curing system  170  repeats steps  306  and  308  to adjust the configuration of the pixelated array  180  as the pixelated array  180  translates. At step  310 , the curing system  170  transmits the pixelated array  180  to the target area  182  at the end position with the pixelated array  180  in an ending configuration. At step  312 , the curing system  170  translates the pixelated array  180  in the ending configuration a threshold amount to achieve the improved resolution at the end position and for a threshold amount of time for the target area  182  to cure at the end position. 
     During a quasi-tile exposure scanning method, the target area  182  is exposed to light emitted by the DLP projector  174  when the pixelated array  180  is at a position along the translation axis A T  and in a set configuration and the target area is not exposed to light emitted by the DLP projector  180  as the pixelated array  180  is translated between positions along the translation axis A T . In other words, the pixelated array  180  is transmitted to the target area  182  at a first position along the translation axis A T  and in a first configuration for an amount of time necessary to cure at least a portion of the layer of the finished component C. The pixelated array  180  is then transmitted to the target area  182  at a second position along the translation axis A T  different from the first position and in a second configuration different from the first configuration for an amount of time necessary to cure at least another portion of the layer of the finished component C. This process is repeated as necessary with the pixelated array  180  transmitted in any number of configurations at any number of positions along the translation axis A T . The pixelated array  180  is not transmitted to the target area  182  as the corresponding components of the curing system  170  are moved or as the configuration of the pixelated array  180  is adjusted. When transmitting the pixelated array  180  to the target area  182  at a position along the translation axis A T , the pixelated array  180  is not perfectly stationary, but rather is translated along the translation axis A T  a threshold amount to provide the improved resolution at each position. 
       FIG.  10    depicts an example quasi-tile exposure scanning method  400 . At step  402 , the light source  172  transmits the pixelated array  180  to the target area  182  at a first or start position, with the pixelated array  180  in a first or starting configuration. At step  404 , the curing system  170  translates the pixelated array  180  along the translation axis A T  a threshold distance to achieve the improved resolution at the start position. The curing system  170  transmits the pixelated array  180  in the starting configuration for at least a threshold amount of time for a portion of the target area  182  to cure responsive to the emitted light. At step  406 , the curing system  170  stops transmitting the pixelated array  180  to the target area  182  so that the curing system  170  may translate the pixelated array  180  along the translation axis A T  without simultaneously transmitting the pixelated array  180 . At step  408 , the curing system  170  transmits the pixelated array  180  to a position different from the start position at the target area  182  in a determined configuration. For example, the configuration may be determined to be the same as the first configuration or the configuration may be different from the first configuration. At step  410 , the curing system  170  determines whether the pixelated array  180  is transmitted at an end position and whether the configuration is an ending configuration. If the pixelated array  180  is not transmitted at the end position in the ending configuration, steps  406  and  408  are repeated until step  410  is true. When the pixelated array  180  is transmitted at the end position in the ending configuration, at step  412 , the curing system  170  translates the pixelated array  180  in the ending configuration a threshold amount to achieve the improved resolution at the end position and for a threshold amount of time for the target area  182  to cure at the end position. 
     When the pixelated array  180  is large enough to cure an entire layer of the finished component C, only a single configuration of the pixelated array  180  may be transmitted to the target area  182 . Rather than translating the pixelated array  180  along the translation axis A T  between positions along the translation axis A T , the pixelated array  180  is merely translated a threshold amount (e.g., less than a pixel width along the translation axis A T ) to provide improved resolution. A scanning method where a configuration of the pixelated array  180  is translated along the translation axis A T  only a threshold amount to achieve improved resolution may be referred to as a single quasi-tile scanning method. 
       FIG.  11    depicts an example single quasi-tile scanning method  500 . At step  502 , the curing system  170  transmits the pixelated array  180  to the target area  182  at a position and in a configuration. At step  504 , the curing system  170  translates the pixelated array  180  along the translation axis AT a threshold amount to achieve the improved resolution for the cured layer. 
     As discussed above, the curing system  170  exposes a portion of the liquid photopolymer resin R to light at a wavelength suitable for curing the resin R for a threshold amount of time in order to cure the portion of the resin. In other words, for a pixel  181   a  of the pixelated array  180  to translate to a portion of the cured layer of resin R, the pixel  181   a  must be activated for a threshold amount of time. Thus, the print time (i.e., the time it takes for a layer of the finished component C to be exposed to the threshold amount of light) is dependent upon such factors as the size of the pixelated array  180 , the size of a pixel  181   a , the area to be cured, and at least in the case of the scanned exposure scanning method, the rate at which the pixels  181   a  may be updated as the pixelated array  180  is translated along the translation axis A T . For example, the liquid photopolymer resin R may have a fluence value (the amount of energy of acitinic radiation a given area of the resin must receive to cure) and the DMD  176  may have a maximum pixel update frequency. If the pixelated array  180  is capable of exposing a portion of the resin to enough acitinic radiation to satisfy the fluence value faster than the pixelated array  180  can be translated and/or faster than the DMD  176  can update the pixels  181   a , the print time may be limited by such factors. In other words, despite other capabilities of the curing system  170 , the print time is dependent upon satisfying the fluence value at each portion of the layer to be cured. 
     Additionally, it should be understood that the total printable area of the curing system  170  may be at least incrementally smaller than the area of the target area  182  which the pixelated array  180  is configured to cover. As shown in  FIGS.  12  and  13   , the translation of the pixelated array  180  along the translation axis A T  means that the printable area (i.e., the area with improved resolution) is a portion of the coverage area.  FIG.  12    depicts a printable area  178  as a portion of the pixelated array  180  where the printable area  178  is represented by a rectangular area perpendicular to the translation axis A T .  FIG.  13    depicts a printable area as a portion of the pixelated array  180  where the printable area  178  is represented by a rectangular area fully within the range of motion of the pixelated array  180  along the translation axis A T . 
     Furthermore, there is a dependence between the drift number N and utilization area of the DMD  176  when aligning the pixelated array  180 , the printable area  178 , and translation axis A T , such as shown in  FIG.  13   . A smaller drift number N results in a higher utilization fraction (how much of the DMD  176  may be used to reflect the pixelated array  180 ). However, even a high drift number (such as 40 or higher) may still allow for a high percentage (such as 98 percent) of the DMD to be utilized to provide the printable area  178 . The aspect ratio of the printable area  178  also is dependent upon the drift number N because of the increased distance the pixelated array  180  is translated along the translation axis A T  to complete a drift cycle measured against the same distance the pixelated array  180  travels across the translation axis A T . However, the aspect ratio of the printable area  178  may remain close to a native aspect ratio of the DMD  176 . For example, the DMD  176  may have a native aspect ratio of 1.778 and an aspect ratio of a pixelated array having a drift number of 40 is above 1.74. In other words, although tilting the pixelated array  180  relative to the translation axis A T  results in a smaller printable area  178  than what would be achievable by a curing system using a non-tilted pixelated array, such area losses are minimal. Optionally, a border of non-printable area may be established around the printable area  178 , resulting in a cropped printable area  186 . 
     Print time can then be calculated as a function of fluence and the distance the pixelated array  180  is translated along the translation axis A T  based on the translation angle θ, the aspect ratio of the total projected area as measured in pixels  181   a , and the dimension of the printable area across the translation axis A T . The local exposure time, which the pixelated array  180  must spend illuminating any given point in order to cure the resin at the given point may be determined as the fluence of the resin divided by the cure plane irradiance. The maximum velocity at which the pixelated array  180  may be translated along the translation axis may be determined as the width of the area to be cured divided by the local exposure time because translating the pixelated array  180  faster than that speed would mean that insufficient time is spent at each pixel  181   a  to satisfy the fluence value. 
     For a quasi-tile exposure scanning method the print time can be determined as the active exposure time plus the jog time between tiles, where the active exposure time is given by the local exposure time multiplied by the minimum number of configurations of the pixelated array  180  required in order to fully cover the print area. The jog time is given by the total distance along the translation axis that the pixelated array  180  is translated divided by the speed at which the pixelated array  180  is translated. Because the pixelated array  180  must be translated at least a threshold amount to provide the improved resolution, the total distance travelled along the translation axis AT cannot be less than or equal to zero. 
     For a scanned exposure scanning method, the print time can be determined as the local exposure time in the starting position plus the local exposure time in the ending position, plus the time spent translating the pixelated array  180  between the start and end positions. The start and end local exposure times are both equal to the local exposure time. The time spent translating the pixelated array between the start and end positions can be determined as the scanned distance divided by the scanning speed. The scanning distance is the total distance along the translation axis that the pixelated array  180  is translated, and the scanning speed is less than or equal to the maximum velocity at which the pixelated array  180  may be translated along the translation axis to satisfy the fluence value, as discussed above. 
       FIGS.  14  and  15    depict graphs comparing the print time of a layer of a finished component via a curing system  170  based on the scanning method and the fluence value of the resin. The graph of  FIG.  14    represents the capabilities of a 3D Printer A and  FIG.  15    represents the capabilities of a 3D Printer B, which are represented by the parameters described in Table 1 below. The capabilities (e.g., outputs) of such 3D printers are represented by Table 2 below. The intercept of the respective plots with the Y-axis of the graphs of  FIGS.  14  and  15    represent the local exposure time for the respective resins and the slope of the plots represents the maximum velocity at which the pixelated array  180  may be translated along the translation axis. The portions  202  of the line plots represent times during a scanning method where the pixelated array  180  illuminates the target area at a start position along the translation axis in a starting configuration and the portions  204  represent the times when the pixelated array  180  in its given configuration is translated by a threshold amount to achieve the improved resolution and cure incrementally additional portions of the resin. The portions  206  of the line plots represent times during a scanned exposure scanning method where the pixelated array  180  is translated continuously along the translation axis A T  at a rate suitable for the liquid photopolymer resin to cure as the pixelated array is translated and adjusted between configurations. The portions  208  of the line plots represent times during a quasi-tile exposure scanning method where the pixelated array  180  illuminates an additional portion of the resin R at a second position along the translation axis A T . 
     
       
         
           
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                 3D  
                 3D  
                   
               
               
                 Input Parameters: 
                 Printer A 
                 Printer B 
                 Units 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 Projected optical power 
                 2.5 
                 2.5 
                 [W] 
               
               
                 Projector-to-resin optical efficiency 
                 1 
                 1 
                 — 
               
               
                 Fluence Required 
                 100 
                 100 
                 [mJ/cm2] 
               
               
                 Print area Y dimension 
                 150 
                 200 
                 [mm] 
               
               
                 Number of projectors along Y 
                 1 
                 2 
                 [integer] 
               
               
                 Overlap between adjacent projectors 
                 N/A 
                 5 
                 [mm] 
               
               
                 X jog velocity for tile exposure 
                 100 
                 100 
                 [mm/s] 
               
               
                 Projector Aspect ratio 
                 1.778 
                 1.778 
                 — 
               
               
                 Projector Vertical Pixels 
                 1080 
                 1080 
                 [ea] 
               
               
                 Projector Horizontal Pixels 
                 1920 
                 1920 
                 [ea] 
               
               
                 Tilt Angle 
                 3.0 
                 3.0 
                 [deg] 
               
               
                 Pixels of Y drift per quasi-tile 
                 1 
                 1 
                 [ea] 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                   
                 3D  
                 3D  
                   
               
               
                 Outputs: 
                 Printer A 
                 Printer B 
                 Units 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 Cropped image X dimension 
                 78.8 
                 53.9 
                 [mm] 
               
               
                 Cropped image Y dimension 
                 150 
                 102.5 
                 [mm] 
               
               
                 Cropped projected area 
                 118 
                 55 
                 [cm2] 
               
               
                 Percent of area lost to crop 
                 11% 
                 11% 
                 — 
               
               
                 Projected Irradiance 
                 18.8 
                 40.2 
                 [mW/cm2] 
               
               
                 Projected pixel pitch 
                 80.2 
                 54.8 
                 [μm] 
               
               
                 X axis travel per pixel of drift 
                 1.5 
                 1.0 
                 [mm] 
               
               
                 X axis travel per quasi tile 
                 1.5 
                 1.0 
                 [mm] 
               
               
                 Effective image width per quasi-tile 
                 77.3 
                 52.8 
                 [mm] 
               
               
                   
               
            
           
         
       
     
     As shown in  FIG.  16    and as described throughout, the curing system  170  may have a single light source  172 , such as a DLP projector  174  that emits light for the DMD  176  to reflect as the pixelated array  180  to illuminate the target area  182 . However, as shown in  FIG.  17   , a curing system  270  may include a plurality of light sources  272 , such as a first DLP projector  274   a  and a second DLP projector  274   b . The first DLP projector  274   a  and the second DLP projector  274   b  may each illuminate light that together combine to provide the pixelated array  180 . The pixelated array  180  may be transmitted to the target area  182  in any suitable manner, such as via a first and second DMD, a single DMD that receives light from both the first DLP projector  274   a  and the second DLP projector  274   b . As shown in  FIG.  17   , each light source  272  illuminates a respective pixelated array  180  tilted relative to the translation axis A T  and that combine to provide the printable area  278  and cropped printable area  286 . The curing system  270  otherwise complies with all aspects of the present disclosure, but emitting light via a plurality of DLP projectors may result in such benefits as being able to cure a larger layer of a finished component C, faster curing time, and/or enhanced resolution. For example, the pixelated array  180  is still rotated by a translation angle θ and translated along only a single translation axis A T . 
     A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other implementations are within the scope of the following claims.