Surface Separation in Resin 3D Printing by Suction Deformation

Abstract

A 3D printer (10) and method for releasing a newly printed layer on a printing platform from transparent window in resin 3D printing. The 3D printer includes a concave contouring bar (600) having a channel adjacent to a surface of the transparent window that faces toward the image projection system (200) and at least one convex contouring bar (610, 620) having a rib that presses against a surface of the transparent window that faces toward the printing platform. An actuator (670) superimposes the concave contouring bar with one of the convex contouring bars to create a cylindrically curved bulge in the transparent window that becomes suctioned to the channel, and the actuator moves the concave contouring bar, along with the cylindrically curved bulge, horizontally across the transparent window to release the newly printed layer from the transparent window.

Description

Atty. Docket No.: BMFP-101-A-WOSURFACE SEPARATION IN RESIN 3D PRINTING BY SUCTION DEFORMATIONFIELD

[0001] This disclosure relates to additive manufacturing, and more particularly, to systems and methods for releasing a transparent window in resin 3D printing from a newly printed layer of a printed sample.BACKGROUND

[0002] Stereolithography was originally conceived as a rapid prototyping technology and refers to a family of technologies that are used to create true-scale models of production components directly from computer aided design (CAD) in a rapid (faster than before) manner. Since its conception, and through its disclosure in U.S. Patent No. 4,575,330, stereolithography has greatly aided engineers, in addition to many others, in visualizing complex three-dimensional part geometries, detecting errors in prototype schematics, testing critical components, and verifying theoretical designs at relatively low costs and much improved time frames.

[0003] During the past decades, continuous improvements in the field of microelectromechanical systems (MEMS) have led to the emergence of micro-stereolithography (pSL), which inherits basic principles from traditional stereolithography but with much higher spatial resolution. See, e.g., Ikuta et al., “Real three dimensional micro fabrication using stereo lithography and metal molding,” Proceedings of MEMS ’93, 6th IEEE Workshop on Micro Electro Mechanical Systems, San Diego, CA, Jan 25-28, 1993, pp. 42-47.

[0004] The resolution of pSL was improved with the development of single-photon polymerization and two-photon polymerization techniques to achieve printed features of less than 200 nm. See, e.g., Maruo et al., “Three-dimensional microfabrication by use of single-photon- absorbed polymerization,” Applied Physics Letters 76(19):2656-2658, 2000; Maruo et al., “Two- photon-absorbed near-infrared photopolymerization for three-dimensional microfabrication,” Journal of Microelectromechanical Systems 7(4):411-415, 1998; and Kawata et al., “Finer features for functional microdevices - micromachines can be created with higher resolution using two- photon absorption” Nature 412(6848):697-698, 2001.

[0005] The speed of pSL was dramatically increased with the development of projection micro-stereolithography (PpSL). See, e.g., Bertsch et al., “Microstereolithography using liquidAtty. Docket No.: BMFP-101-A-WO crystal display as dynamic mask- generator,” Microsystem Technologies, 3(2):42-47, 1997; and Beluze et al., “Microstereolithography: A New Process to Build Complex 3D Objections, Symposium on Design, Test and Microfabrication of MEMs / MOEMs,” Proceedings of SPIE 3680(2):808-817, 1999. The core of this technology is a high resolution spatial light modulator, which is either a liquid crystal display (LCD) panel or a digital light processing (DLP) panel, each of which are available from micro-display industries.

[0006] While PpSL technology has been successful in delivering fast fabrication speed with good resolution, further improvements are still needed, for example, in the field of 3D bioprinting with live cells, samples are required to be ready in minutes. During PpSL printing, a resin layer is defined between a vat (or reservoir) of resin and the sample stage. A “sample” may refer to the 3-D model as it is being printed layer by layer, and a “sample stage” may refer to the most recently printed layer of the sample. There are at least three methods for defining the resin layer in PpSL. A first method uses a free surface where the layer thickness is defined by a distance between the resin’s free surface and a sample stage. However, with this method it may take more than a half an hour to define a 10 pm thick resin layer having a viscosity of 50 cP over a 1 cm by 1 cm area. One reason for slow printing is because of the slow viscous motion of resins. Second and third methods for defining the resin layer in PpSL use a transparent membrane or a transparent plate, respectively. A membrane is typically soft, pliable, and durable, whereas a plate is typically hard, rigid, and durable. However, a thin plate, for example, having a thickness of approximately 50-150 pm, is bendable and may be locally deformable, as explained further herein. The term “transparent window” may be used herein to refer to either a transparent membrane or a transparent plate.

[0007] Some materials of the transparent window, such as glass, quartz, Teflon® perfluoroalkoxy (PF A), or Teflon® fluorinated ethylene propylene (FEP), may be substantially impermeable to gas. Other materials of the transparent window, such as polydimethylsiloxane (PDMS) or Teflon® amorphous polymers (AF), may be permeable to gas (specifically permeable to oxygen). Continuous Liquid Interface Production System (CLIPS) is a 3D printing technology that utilizes oxygen-permeable transparent window. Gas permeability may be desired to reduce the adhesion between the membrane and the printing part. This is because oxygen permeating through the membrane may create a photo polymerization inhibition layer, or “dead zone,” that may result in a residual layer of uncured resin between the membrane and the printing part. As gasAtty. Docket No.: BMFP-101-A-WO permeability of the membrane increases, the adhesion between the membrane and the printed sample decreases. Unfortunately, the thickness of the inhibition layer, which is generally 10-50 pm, may create significant dimensional error in precision 3D printing, where tolerance requirements may be similar to, or even less than, the thickness of the inhibition layer. Further, a thick oxygen inhibition layer results in a thick layer of residual uncured resin. Because the resin has a high viscosity, the thick layer of residual uncured resin can significantly reduce the overall printing speed, especially for dense parts without internal channel connections. Therefore, in many precision 3D printing applications, a zero-thickness or ultra-thin oxygen inhibition layer is desired, and accordingly, substantially oxygen-impermeable transparent windows are utilized. As a result, excessive adhesion between the transparent window and the printed sample is experienced.

[0008] As can be appreciated, rapid and effective separation of the transparent window from the printed sample is critical. U.S. Patent No. 7,438,846 discloses a method of using a combination of a transparent membrane and transparent plate for projection-from -below type resin printing. CN Patent No. 10982289 IB discloses a method of using a using a releasing membrane for projection-from-above type resin printing. But both methods rely on a Z-stage (vertical movement of a printing platform with respect to gravity) to pull and peel the whole membrane away from a most recently printed layer and then move the printing platform back for a next layer of printing. The movement of the stage can take up to 4-6 seconds, and the top-down type resin printing method can require an additional 10-20 seconds for the new resin layer to settle. Hence, both methods slow down the resin printing process.SUMMARY

[0009] The disclosed embodiments provide for a 3D printing system having a transparent window, disposed horizontally with respect to gravity in a resin vat and adjacent to an opening in the resin vat, between an image projection system and a printing platform in the resin vat, and a first actuator configured to move the printing platform or the resin vat vertically with respect to gravity. The system includes a first contouring bar and a second contouring bar for forming a cylindrically curved contour, or bulge, in the transparent window. The first contouring bar has a channel that substantially spans between lateral edges of the opening and comprises a concave profile adjacent to a surface of the transparent window that faces toward the image projection system. The second contouring bar is parallel to the first contouring bar and disposed near a firstAtty. Docket No.: BMFP-101-A-WO longitudinal edge of the opening, having a first rib comprising a first convex profile that presses against a surface of the transparent window that faces toward the printing platform. The system includes a second actuator configured to superimpose the first contouring bar with the second contouring bar to create a cylindrically curved bulge in the transparent window that substantially mimics the channel and is suctioned to the channel, and the second actuator is further configured to move the first contouring bar between the first longitudinal edge of the opening and a second longitudinal edge of the opening.

[0010] In some embodiments, the system, includes a third contouring bar, parallel to the first contouring bar and disposed near the second longitudinal edge of the opening, having a second rib comprising a second convex profile that presses against the surface of the transparent window that faces toward the printing platform, where the second actuator further configured to superimpose the first contouring bar with the third contouring bar to recreate the cylindrically curved bulge in the transparent window that substantially mimics the channel and is suctioned to the channel.

[0011] In some embodiments, the system includes a lubricant between the surface of the transparent window that faces toward the image projection system and the channel.

[0012] Some disclosed embodiments include a method of using the 3D printing system, including the steps of: (1) exposing a layer of resin between the transparent window and the printing platform to light from the image projection system, causing select portions of the resin to cure; (2) vertically moving the printing platform a layer-thickness distance away from the image projection system by the first actuator; (3) superimposing the first contouring bar with the second contouring bar by the second actuator, creating the cylindrically curved bulge in the transparent window that is suctioned to the channel; and (4) moving the first contouring bar between the first longitudinal edge of the opening and a second longitudinal edge of the opening by the second actuator, causing the select portions of the layer of resin to detach from the transparent window.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] A more complete appreciation of the present disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.Atty. Docket No.: BMFP-101-A-WO

[0014] FIG. 1A shows a plan view of an example of a 3D printing system and FIG. IB shows a plan view of the 3D printing system from below.

[0015] FIG. 2A shows a perspective view of a concave contouring bar and a first convex contouring bar; FIG. 2B shows a perspective view of the concave contouring bar superimposed with the first convex contouring bar; and FIG. 2C shows a perspective view of the concave contouring bar superimposed with the first convex contouring bar and a second convex contouring bar separated therefrom by a distance.

[0016] FIGS. 3A-3C show respective side views of a concave contouring bar comprising an elastomer, where FIG. 3A shows the concave contouring bar in a relaxed state; FIG. 3B shows the concave contouring bar in a widened state of flex; and FIG. 3C shows the concave contouring bar in a narrowed state of flex.

[0017] FIG. 4 shows a perspective view of a concave contouring bar, a convex contouring bar, and a transparent window having a cylindrically curved bulge.

[0018] FIGS. 5A-5E show respective side views of the 3D printing system of FIGS. 1A- 1B at successive stages of separating the transparent window from a printed sample.

[0019] FIG. 6 shows a flowchart of an example of a technique for separating a transparent window from a printed sample using the 3D printing system of either FIGS. 1A-1B.DETAILED DESCRIPTION

[0020] The present disclosure may be more readily understood by reference to the following detailed description and the accompanying drawings, which form a part of this disclosure. This disclosure is not limited to the specific devices, methods, conditions, or parameters described and / or shown herein, and the terminology used herein is for the purpose of describing particular embodiments by way of example only and is not intended to be limiting of disclosed embodiments or inventions. For example, “top,” “bottom,” “left,” “right,” “clockwise,” and “counterclockwise” may be used as specific examples of generally opposite orientations or directions, respectively. Also, as used in the specification and including the appended claims, the singular forms “a,” “an,” and “the” include the plural, and reference to a particular numerical value includes at least that particular value, unless the context clearly dictates otherwise.

[0021] The following numerals are used to describe various features of the embodiments: 3D printing system 10; printed layer 20; transparent window 100; outer surface 110; inner surfaceAtty. Docket No.: BMFP-101-A-WO120; image projection system 200; DLP light source 210; DLP panel 220; printing platform 300; resin vat 400; opening 410; left edge 420; right edge 430; near edge 440; far edge 450; opening width 460; opening length 470; concave contouring bar 600; concave surface 602; concave-surface radius 604; concave-surface length 606; first convex contouring bar 610; first convex surface 612; first convex- surface radius 614; first convex-surface length 616; second convex contouring bar 620; second convex surface 622; second convex-surface radius 624; second convex-surface length 626; cylindrically curved bulge 660; travel direction 670; bulge height 680; first actuator 700; and second actuator 710.

[0022] FIGS. 1A-1B show an embodiment of an example of a 3D printing system 10 suitable for projection-from-above type resin printing. The 3D printing system comprises a transparent window 100 disposed horizontally with respect to gravity in a resin vat 400, where gravity is indicated by the arrow and the letter “g.” The transparent window 100 is disposed at or near an upper portion of the resin vat 400, adjacent to an opening 410 in an upper wall of the resin vat 400. The transparent window 100 may comprise a durable membrane or a flexible plate. A membrane may be soft, pliable, and durable, whereas a plate may be hard, semi-rigid, and durable. However, a thin plate, for example, having a thickness of approximately 50-150 pm, may be bendable and may be locally deformable, as explained further herein. In some embodiments, the transparent window 100 is approximately coextensive with the opening 410.

[0023] The transparent window 100 is disposed between an image projection system 200 and a printing platform 300 that is in the resin vat 400. In FIGS. 1A-1B, the image projection system 200 is disposed gravitationally above the transparent window 100, and it comprises a DLP system having a DLP light source 210 and a DLP panel 220. The image projection system 200 may include, or be communicatively coupled to, a control computer, comprising a memory for storing instructions and a processor for executing the instructions, configured to provide image information for the image projection system 200. In some embodiments, the image projection system 200 may comprise a reflective liquid crystal display (LCD) projector and an LCD light source.

[0024] The 3D printing system 10 includes a first actuator 700, or Z-stage, coupled to the printing platform 300 or the resin vat 400 (or both), that is configured to move either the printing platform 300 or the resin vat 400 (or both) vertically with respect to gravity. The first actuator 700 may be communicatively coupled to a control computer, comprising a memory for storingAtty. Docket No.: BMFP-101-A-WO instructions and a processor for executing the instructions, to transmit control signals to the first actuator 700. As shown in FIGS. 1A-1B, the first actuator 700 is coupled to the printing platform 300 and is configured to vertically position the printing platform 300, or a most recently printed layer 20 that has been formed on the printing platform 300, a layer-thickness distance from a surface of the transparent window 100 that faces toward the printing platform 300, referred to herein as an inner surface 120 (e.g., because it faces into the resin vat 400). In some implementations, the layer-thickness distance is approximately 10-50 pm.

[0025] The opening 410 may be rectangular, having opposite lateral edges (e.g., a left edge 420 and a right edge 430) that define an opening width 460 and opposite longitudinal edges (e.g., a near edge 440 that is, for example, adjacent to the first actuator 700, and a far edge 450) that define an opening length 470. Close to the near edge 440 of the opening 410 is a first convex contouring bar 610, and close to the far edge 450 of the opening 410 is a second convex contouring bar 620. The first convex contouring bar 610 and the second convex contouring bar 620 are substantially parallel to each other and oriented in a plane that is substantially parallel to the transparent window 100. As shown in FIGS. 2A-2C, the first convex contouring bar 610 comprises a first convex surface 612 that has a first convex-surface radius 614 that extends along a first convex-surface length 616. Similarly, as shown in FIG. 2C, the second convex contouring bar 620 (on the right) comprises a second convex surface 622 that has a second convex-surface radius 624 that extends along a second convex-surface length 626. The first convex surface 612 and the second convex surface 622 may each be referred to herein as a rib. In some embodiments, a profile of each of the first convex surface 612 and the second convex surface 622 is curved and comprises at least one of a circular profile, a sinusoidal profile, a catenary profile, an elliptical profile, a parabolic profile, a hyperbolic profile, or a Gaussian profile. In some embodiments, the first convex surface 612 and the second convex surface 622 have a same profile, and in other embodiments, they have different profiles.

[0026] As shown in FIGS. 1A-1B, each of the first convex surface 612 and the second convex surface 622 presses against a surface of the transparent window 100 that faces toward the printing platform 300. In some embodiments, each of the first convex-surface length 616 and the second convex-surface length 626 is equal to or greater than a width of the transparent window 100, e.g., approximately equal to the opening width 460 when the transparent window 100 is approximately coextensive with the opening 410.Atty. Docket No.: BMFP-101-A-WO

[0027] The 3D printing system 10 also includes a concave contouring bar 600 that comprises a concave surface 602 that has a concave-surface radius 604 that extends along a concave-surface length 606. In some embodiments, the concave-surface length 606 is equal to or greater than a width of the transparent window 100, e.g., approximately equal to the opening width 460 when the transparent window 100 is approximately coextensive with the opening 410.

[0028] The concave surface 602 may be referred to herein as a channel. In some embodiments, a profde of the concave surface 602 is curved and comprises at least one of a circular profde, a sinusoidal profde, a catenary profde, an elliptical profde, a parabolic profde, a hyperbolic profde, or a Gaussian profde. In some embodiments, the concave surface 602 is complementary to one or both of the first convex surface 612 and the second convex surface 622. In some embodiments, the concave surface 602 has a radius of approximately 2-5 mm. In some embodiments, the concave surface 602 has a depth of approximately 1-3 mm.

[0029] As shown in FIGS. 1A-1B, the concave surface 602 is adjacent to a surface of the transparent window 100 that faces toward the image projection system, referred to herein as an outer surface 110 (e.g., because it faces out from the resin vat 400, and the outer surface 110 is opposite the inner surface 120). The concave contouring bar 600 is coupled to a second actuator 710 (e.g., an XY stage) that is configured to superimpose, or overlap, the concave contouring bar 600 with the first convex contouring bar 610 to create a cylindrically curved bulge 660 in the transparent window 100 that substantially mimics the concave surface 602 and is suctioned to the concave surface 602. The second actuator 710 is further configured to move the concave contouring bar 600 in the direction 670 between the near edge 440 of the opening 410 and the far edge 450 of the opening 410.

[0030] As the concave contouring bar 600 moves, or glides, along the outer surface 110 of the transparent window 100 in the direction 670 by means of the second actuator 710, the cylindrically curved bulge 660 follows, or travels with, the concave contouring bar 600 due to the suction between the outer surface 110 and the concave surface 602. As the cylindrically curved bulge 660 passes over the most recently printed layer 20 on the printing platform 300, the cylindrically curved bulge 660 peels, or separates, the transparent window 100 from the most recently printed layer 20, as explained more fully later herein. In some embodiments, the outer surface 110 of the transparent window 100 and / or the concave surface 602 of the concave contouring bar 600 is coated with a lubricant to help form and / or maintain the suction between theAtty. Docket No.: BMFP-101-A-WO outer surface 1 10 and the concave surface 602 and / or to reduce friction between the outer surface 110 and the concave surface 602.

[0031] In some embodiments, the concave surface 602 of the concave contouring bar 600 comprises an elastomer. FIGS. 3A-3C show an example of the concave surface 602 comprising an elastomer that is capable of flexing, where FIG. 3A shows the concave surface 602 in a relaxed state; FIG. 3B shows the concave surface 602 flexed to a widened state (e.g., the concave-surface radius 604 has increased relative to the relaxed state); and FIG. 3C shows the concave surface 602 flexed to a narrowed state (e.g., the concave-surface radius 604 has decreased relative to the relaxed state). Flexing of the elastomer allows the concave contouring bar 600 to be readily superimposed with either the first convex contouring bar 610 or the second convex contouring bar 620 when the concave contouring bar 600 is moved in the direction 670 (e.g., parallel to the transparent window). As the concave contouring bar 600 approaches a given convex contouring bar along the direction 670, say the first convex contouring bar 610, the first convex surface 612 causes the concave surface 602 of the concave contouring bar 600 to widen and thereby superimpose the first convex surface 612. Flexing of the elastomer may also help to form and / or maintain the suction between the outer surface 110 of the transparent window 100 and the concave surface 602 of the concave contouring bar 600.

[0032] The second actuator 710 is further configured to superimpose, or overlap, the concave contouring bar 600 with the second convex contouring bar 620 to recreate (or to create) the cylindrically curved bulge 660 in the transparent window 100 that substantially mimics the concave surface 602 and is suctioned to the concave surface 602. Recreation of the cylindrically curved bulge 660 may be necessary because the cylindrically curved bulge 660 may flatten or otherwise lose its shape and / or its suction to the concave surface 602 when it passes over the most recently printed layer 20 on the printing platform 300. The presence of both the first convex contouring bar 610 and the second convex contouring bar 620 allows the concave contouring bar 600 to make a single pass across the transparent window 100 between the near edge 440 and the far edge 450 for each separation action. Some embodiments include only one convex contouring bar, such as the first convex contouring bar 610, and accordingly, the concave contouring bar 600 may need to return to the first convex contouring bar 610 after each separation action to recreate the cylindrically curved bulge 660, thereby incurring two passes across the transparent window 100 for each separation action.Atty. Docket No.: BMFP-101-A-WO

[0033] FIG. 4 shows the concave contouring bar 600, the first convex contouring bar 610, and the transparent window 100 having a cylindrically curved bulge 660, where these components are illustrated with exaggerated vertical separations to aid visualization. Superimposing the concave contouring bar 600 with the first convex contouring bar 610 effectively sandwiches, or squeezes, the transparent window 100 between the concave surface 602 and the first convex surface 612, thereby forming the cylindrically curved bulge 660. The cylindrically curved bulge 660 comprises a height 680 that extends at least the concave-surface length 606. In some embodiments, the height 680 is approximately 100-300 pm.

[0034] FIGS. 5A-5E show respective side views of the 3D printing system 10 at successive stages during 3D printing of a printed sample. In FIGS. 5A-5E, the resin vat 400 is filled with a resin, e.g., a light-curable liquid that may comprise one or more printing resins that may include solid particles used in 3D printing applications.

[0035] In FIG. 5A, several layers of the printed sample have already been printed. Further, the most recently printed layer 20 of the printed sample (e.g., the most recently cured layer of resin) that is coupled to the printing platform 300 has already been vertically positioned, for example, by the first actuator 700, to a distance from the inner surface 120 of the transparent window 100 that corresponds to a layer-thickness for the 3D printing system 10. In some implementations, the layer-thickness distance may vary from layer to layer. Between the most recently printed layer and the inner surface 120 is a layer of uncured resin. As shown in FIG. 5A, the image projection system 200 directs patterned light (e.g., an image) toward the transparent window 100, which causes select portions of the layer of uncured resin to cure, e.g., to solidify and additively form a new layer of the printed sample. As explained earlier, the newly printed layer (or portions thereof) may be adhered to the inner surface 120 of the transparent window 100. At or around the time that the image projection system 200 directs patterned light toward the transparent window 100 (e.g., before, during, or after), the concave contouring bar 600 has been superimposed with the first convex contouring bar 610, by the second actuator 710 (not shown), thereby creating or recreating the cylindrically curved bulge 660.

[0036] In FIG. 5B, the printing platform 300 (and the printed sample coupled thereto) has been moved vertically away from the image projection system 200 by a layer-thickness distance from the transparent window 100. In the projection -from above 3D printing system depicted in FIGS. 5A-5E, the printing platform 300 has been moved downward (in a projection-from-aboveAtty. Docket No.: BMFP-101-A-WO3D printing system, the printing platform 300 would be moved upward). Because the newly printed layer (or portions thereof) may be adhered to the transparent window 100, the downward motion of the printing platform 300 with respect to the relatively stationary transparent window 100 causes the transparent window 100 to be pulled downward along with the newly printed layer. At or around the time that the printing platform 300 has been moved downward (e.g., before, during, or after), the concave contouring bar 600 is moved horizontally away from one edge of the opening 410, e.g., the near edge 440, and toward an opposite edge of the opening 410, e.g., the far edge 450. The cylindrically curved bulge 660 follows the concave contouring bar 600.

[0037] In FIG. 5C, the concave contouring bar 600 is moved horizontally past the printed sample, for example, by the second actuator 710 (not shown in FIGS. 5A-5E), causing the cylindrically curved bulge 660 to move therewith. The motion of the cylindrically curved bulge 660 across the printed sample peels the transparent window 100 from the newly printed layer. Because the concave contouring bar 600 slides, glides, or otherwise translates across the inner surface 120, the lubricant may be utilized at the interface between the concave surface 602 and the outer surface 110.

[0038] In FIG. 5D, the concave contouring bar 600 has been moved completely past the printed sample, e.g., from the near edge 440 of the opening 410 to the far edge 450 of the opening 410, and superimposed with the second convex contouring bar 620 for recreation of the cylindrically curved bulge 660. At this point, the newly printed layer has been detached from the transparent window 100, and simultaneously, fresh uncured resin has filled the layer-thickness space between the just-detached printed layer and the inner surface 120 of the transparent window 100.

[0039] In FIG. 5E, the image projection system 200 again directs patterned light (e.g., an image) toward the transparent window 100, which causes select portions of the layer of uncured resin to cure, e.g., to solidify and additively form another layer of the printed sample. FIG. 5E is similar to FIG. 5A, except that the concave contouring bar 600 is positioned at opposite edges of the opening 410.

[0040] The embodiments described with reference to FIGS. 1-5 may be suitable for several types of 3D printing technologies, for example PpSL or stereolithography (SLA). For PpSL, the image projection system 200 may comprise a DLP projector or an LCD projector, and for SLA,Atty. Docket No.: BMFP-101-A-WO the image projection system 200 may comprise steering mirrors, called galvanometers, to steer a laser beam that is directed toward the transparent window 100 (and uncured resin adj acent thereto).

[0041] To further describe some embodiments in greater detail, reference is next made to an example of a technique 6000 which may be performed by or using the 3D printing system 10 of FIGS. 1-5. FIG. 6 is a flowchart of an example of a technique for separating a transparent window 100 from a printed sample the 3D printing system 10 of FIGS. 1-5. For simplicity of explanation, the technique 6000 is depicted and described herein as a series of steps or operations. However, the steps or operations of the technique 6000 in accordance with this disclosure can occur in various orders and / or concurrently. Additionally, other steps or operations not presented and described herein may be used. Furthermore, not all illustrated steps or operations may be required to implement a technique in accordance with the disclosed subject matter.

[0042] Referring to FIG. 6, the step 6010 comprises operating a 3D printer comprising: a transparent window, disposed horizontally with respect to gravity in a resin vat and adjacent to an opening in the resin vat, between an image projection system and a printing platform in the resin vat; a first actuator configured to move the printing platform or the resin vat vertically with respect to gravity; a concave contouring bar having a channel that substantially spans between lateral edges of the opening and comprising a concave profile adjacent to a surface of the transparent window that faces toward the image projection system; a first convex contouring bar, parallel to the concave contouring bar and disposed near a first longitudinal edge of the opening, having a first rib comprising a first convex profile that presses against a surface of the transparent window that faces toward the printing platform; a second actuator configured to superimpose the concave contouring bar with the first convex contouring bar to create a cylindrically curved bulge in the transparent window that substantially mimics the channel and is suctioned to the channel; and the second actuator is further configured to move the concave contouring bar between the first longitudinal edge of the opening and a second longitudinal edge of the opening.

[0043] In some implementations, the 3D printer may be the 3D printing system 10; the transparent window may be the transparent window 100; the resin vat may be the resin vat 400; the opening may be the opening 410; the image projection system may be the image projectionAtty. Docket No.: BMFP-101-A-WO system 200; the printing platform may be the printing platform 300; the first actuator may be the first actuator 700; the concave contouring bar may be the concave contouring bar 600; the concave profile may be a profile of the concave surface 602; the surface of the transparent window that faces toward the image projection system may be the outer surface 110; the first convex contouring bar may be the first convex contouring bar 610; the first longitudinal edge of the opening may be the near edge 440; the first rib may be the first convex surface 612; the first convex profile may be a profile of the first convex surface 612; the surface of the transparent window that faces toward the printing platform may be the inner surface 120; the second actuator may be the second actuator 710; the cylindrically curved bulge may be the cylindrically curved bulge 660; and the second longitudinal edge of the opening may be the far edge 450.

[0044] In some implementations, the image projection system may include, or be communicatively coupled to, a control computer configured to provide image information for the image projection system. In some implementations, the image projection system is gravitationally above the resin vat, such as in the 3D printing system 10 shown in FIGS. 1A-1B, and in other implementations, the image projection system is gravitationally below the resin vat. In some implementations, the transparent window comprises a membrane, and in other implementations, the transparent window comprises a flexible plate having a thickness of approximately 50-150 pm.

[0045] The step 6020 comprises exposing a layer of resin between the transparent window and the printing platform to light from the image projection system, causing select portions of the resin to cure. The step 6020 may correspond to the stage of 3D printing depicted in FIG. 5 A.

[0046] The step 6030 comprises vertically moving the printing platform a layer-thickness distance away from the image projection system by the first actuator. The step 6030 may correspond to the stage of 3D printing depicted in FIG. 5B. The first actuator may be communicatively coupled to a control computer, comprising a memory for storing instructions and a processor for executing the instructions, to transmit control signals to the first actuator.

[0047] The step 6040 comprises superimposing the concave contouring bar with the first convex contouring bar by the second actuator, creating the cylindrically curved bulge in the transparent window that is suctioned to the channel. The step 6040 may correspond to the stage of 3D printing depicted in FIGS. 5 A, 5D, or 5E with respect to the concave contouring bar 600 superimposed with the first convex contouring bar 610 (FIG. 5 A) or the second convex contouring bar 620 (FIGS. 5D-5E). In some implementations, the concave profile of the channel comprises aAtty. Docket No.: BMFP-101-A-WO radius of approximately 2-5 mm; the concave profile of the channel comprises a depth of approximately 1-3 mm; and / or the cylindrically curved bulge has a height of approximately 100- 300 pm.

[0048] The step 6050 comprises moving the concave contouring bar between the first longitudinal edge of the opening and the second longitudinal edge of the opening by the second actuator, causing the select portions of the layer of resin to detach from the transparent window. The step 6040 may correspond to the stages of 3D printing depicted in FIGS. 5B-5D with respect to horizontally moving the concave contouring bar 600.

[0049] Some embodiments disclosed herein include a 3D printing system, or a 3D printer, comprising: a transparent window, disposed horizontally with respect to gravity in a resin vat and adjacent to an opening in the resin vat, between an image projection system and a printing platform in the resin vat; a first actuator configured to move the printing platform or the resin vat vertically with respect to gravity; a concave contouring bar having a channel that substantially spans between lateral edges of the opening and comprising a concave profile adjacent to a surface of the transparent window that faces toward the image projection system; a first convex contouring bar, parallel to the concave contouring bar and disposed near a first longitudinal edge of the opening, having a first rib comprising a first convex profile that presses against a surface of the transparent window that faces toward the printing platform; a second actuator configured to superimpose the concave contouring bar with the first convex contouring bar to create a cylindrically curved bulge in the transparent window that substantially mimics the channel and is suctioned to the channel; and the second actuator is further configured to move the concave contouring bar between the first longitudinal edge of the opening and a second longitudinal edge of the opening.

[0050] In some implementations, the 3D printer further comprises: a second convex contouring bar, parallel to the concave contouring bar and disposed near the second longitudinal edge of the opening, having a second rib comprising a second convex profile that presses against the surface of the transparent window that faces toward the printing platform; and the second actuator further configured to superimpose the concave contouring bar with the second convex contouring bar to recreate the cylindrically curved bulge in the transparent window that substantially mimics the channel and is suctioned to the channel.Atty. Docket No.: BMFP-101-A-WO

[0051] In some implementations, the 3D printing system further comprises: a lubricant between the surface of the transparent window that faces toward the image projection system and the channel.

[0052] In some implementations, the image projection system is gravitationally above the resin vat.

[0053] In some implementations, the image projection system is gravitationally below the resin vat.

[0054] In some implementations, the image projection system comprises a digital light projection (DLP) projector.

[0055] In some implementations, the image projection system comprises a reflective liquid crystal display (LCD) projector.

[0056] In some implementations, the transparent window comprises a membrane.

[0057] In some implementations, the transparent window comprises a flexible plate having a thickness of approximately 50-150 pm.

[0058] In some implementations, the concave profile comprises a radius of approximately 2-5 mm

[0059] In some implementations, the concave profile comprises a depth of approximately 1-3 mm.

[0060] In some implementations, the channel comprises an elastomer; wherein flexing the elastomer in a first direction causes the channel to widen; and flexing the elastomer in a second direction causes the channel to narrow.

[0061] In some implementations, the channel comprises an elastomer; and the concave profile has a radius that is less than or equal to a radius of the first convex profile

[0062] In some implementations, the concave profile comprises at least one of: a circular profile; a sinusoidal profile; a catenary profile; an elliptical profile; a parabolic profile; a hyperbolic profile; or a Gaussian profile

[0063] In some implementations, a height of the cylindrically curved bulge is approximately 100-500 pm.

[0064] Some embodiments disclosed herein include a method of using a 3D printer that comprises: a transparent window, disposed horizontally with respect to gravity in a resin vat and adjacent to an opening in the resin vat, between an image projection system and a printing platformAtty. Docket No.: BMFP-101-A-WO in the resin vat; a first actuator configured to move the printing platform or the resin vat vertically with respect to gravity; a concave contouring bar having a channel that substantially spans between lateral edges of the opening and comprising a concave profile adjacent to a surface of the transparent window that faces toward the image projection system; a first convex contouring bar, parallel to the concave contouring bar and disposed near a first longitudinal edge of the opening, having a first rib comprising a first convex profile that presses against a surface of the transparent window that faces toward the printing platform; a second actuator configured to superimpose the concave contouring bar with the first convex contouring bar to create a cylindrically curved bulge in the transparent window that substantially mimics the channel and is suctioned to the channel; and the second actuator is further configured to move the concave contouring bar between the first longitudinal edge of the opening and a second longitudinal edge of the opening; the method comprising: exposing a layer of resin between the transparent window and the printing platform to light from the image projection system, causing select portions of the resin to cure; vertically moving the printing platform a layer-thickness distance away from the image projection system by the first actuator; superimposing the concave contouring bar with the first convex contouring bar by the second actuator, creating the cylindrically curved bulge in the transparent window that is suctioned to the channel; and moving the concave contouring bar between the first longitudinal edge of the opening and the second longitudinal edge of the opening by the second actuator, causing the select portions of the layer of resin to detach from the transparent window

[0065] In some implementations, the method further comprises: applying a lubricant between the surface of the transparent window that faces toward the image projection system and the channel.

[0066] In some implementations, the channel comprises an elastomer.

[0067] Some embodiments disclosed herein include a method of using a 3D printer that comprises: a transparent window, disposed horizontally with respect to gravity in a resin vat and adjacent to an opening in the resin vat, between an image projection system and a printing platform in the resin vat; a first actuator configured to move the printing platform or the resin vat vertically with respect to gravity; a concave contouring bar having a channel that substantially spans between lateral edges of the opening and comprising a concave profile adjacent to a surface of the transparent window that faces toward the image projection system; a first convex contouring bar, parallel to the concave contouring bar and disposed near a first longitudinal edge of the opening,Atty. Docket No.: BMFP-101-A-WO having a first rib comprising a first convex profile that presses against a surface of the transparent window that faces toward the printing platform; a second actuator configured to superimpose the concave contouring bar with the first convex contouring bar to create a cylindrically curved bulge in the transparent window that substantially mimics the channel and is suctioned to the channel; the second actuator is further configured to move the concave contouring bar between the first longitudinal edge of the opening and a second longitudinal edge of the opening; a second convex contouring bar, parallel to the concave contouring bar and disposed near the second longitudinal edge of the opening, having a second rib comprising a second convex profile that presses against the surface of the transparent window that faces toward the printing platform; and the second actuator further configured to superimpose the concave contouring bar with the second convex contouring bar to recreate the cylindrically curved bulge in the transparent window that substantially mimics the channel and is suctioned to the channel; the method comprising: exposing a layer of resin between the transparent window and the printing platform to light from the image projection system, causing select portions of the resin to cure; vertically moving the printing platform a layer-thickness distance away from the image projection system by the first actuator; superimposing the concave contouring bar with the first convex contouring bar by the second actuator, creating the cylindrically curved bulge in the transparent window that is suctioned to the channel; moving the concave contouring bar between the first longitudinal edge of the opening and a second longitudinal edge of the opening by the second actuator, causing the select portions of the layer of resin to detach from the transparent window; and superimposing the concave contouring bar with the second convex contouring bar by the second actuator, recreating the cylindrically curved bulge in the transparent window that is suctioned to the channel.

[0068] In some implementations, the method further comprises: applying a lubricant between the surface of the transparent window that faces toward the image projection system and the channel.

[0069] While several embodiments of the disclosure have been shown in the drawings, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments.

Claims

Atty. Docket No.: BMFP-101-A-WOWHAT IS CLAIMED IS:

1. A 3D printing system, comprising: a transparent window, disposed horizontally with respect to gravity in a resin vat and adjacent to an opening in the resin vat, between an image projection system and a printing platform in the resin vat; a first actuator configured to move the printing platform or the resin vat vertically with respect to gravity; a concave contouring bar having a channel that substantially spans between lateral edges of the opening and comprising a concave profile adjacent to a surface of the transparent window that faces toward the image projection system; a first convex contouring bar, parallel to the concave contouring bar and disposed near a first longitudinal edge of the opening, having a first rib comprising a first convex profile that presses against a surface of the transparent window that faces toward the printing platform; a second actuator configured to superimpose the concave contouring bar with the first convex contouring bar to create a cylindrically curved bulge in the transparent window that substantially mimics the channel and is suctioned to the channel; and the second actuator is further configured to move the concave contouring bar between the first longitudinal edge of the opening and a second longitudinal edge of the opening.

2. The 3D printing system of claim 1, further comprising: a second convex contouring bar, parallel to the concave contouring bar and disposed near the second longitudinal edge of the opening, having a second rib comprising a second convex profile that presses against the surface of the transparent window that faces toward the printing platform; and the second actuator further configured to superimpose the concave contouring bar with the second convex contouring bar to recreate the cylindrically curved bulge in the transparent window that substantially mimics the channel and is suctioned to the channel.

3. The 3D printing system of any one of claims 1 to 2, further comprising: a lubricant between the surface of the transparent window that faces toward the image projection system and the channel.Atty. Docket No.: BMFP-101-A-WO4. The 3D printing system of any one of claims 1 to 3, wherein: the image projection system is gravitationally above the resin vat.

5. The 3D printing system of any one of claims 1 to 3, wherein: the image projection system is gravitationally below the resin vat.

6. The 3D printing system of any one of claims 1 to 3, wherein: the image projection system comprises a digital light projection (DLP) projector.

7. The 3D printing system of any one of claims 1 to 3 or claim 6, wherein: the image projection system comprises a reflective liquid crystal display (LCD) projector.

8. The 3D printing system of any one of claims 1 to 3, claim 6, or claim 7, wherein: the transparent window comprises a membrane.

9. The 3D printing system of any one of claims 1 to 3, claim 6, or claim 7, wherein: the transparent window comprises a flexible plate having a thickness of approximately 50-150 pm.

10. The 3D printing system of any one of claims 1 to 3, claim 6, or claim 7, wherein: the concave profile comprises a radius of approximately 2-5 mm.

11. The 3D printing system of any one of claims 1 to 3, claim 6, or claim 7, wherein: the concave profile comprises a depth of approximately 1-3 mm.

12. The 3D printing system of any one of claims 1 to 3, claim 6, claim 7, claim 10, or claim 11, wherein: the channel comprises an elastomer; wherein flexing the elastomer in a first direction causes the channel to widen; and flexing the elastomer in a second direction causes the channel to narrow.Atty. Docket No.: BMFP-101-A-WO13. The 3D printing system of any one of claims 1 to 3, claim 6, claim 7, or claims 10 to 12, wherein: the channel comprises an elastomer; and the concave profile has a radius that is less than or equal to a radius of the first convex profile.

14. The 3D printing system of any one of claims 1 to 3, claim 6, claim 7, or claims 10 to 12, wherein the concave profile comprises at least one of: a circular profile; a sinusoidal profile; a catenary profile; an elliptical profile; a parabolic profile; a hyperbolic profile; or a Gaussian profile.

15. The 3D printing system of any one of claims 1 to 3, claim 6, claim 7, or claims 10 to 13, wherein: a height of the cylindrically curved bulge is approximately 100-500 pm.

16. A method of using the 3D printing system of any one of claims 1 to 3, claim 6, claim 7, or claims 10 to 13, comprising: exposing a layer of resin between the transparent window and the printing platform to light from the image projection system, causing select portions of the resin to cure; vertically moving the printing platform a layer-thickness distance away from the image projection system by the first actuator; superimposing the concave contouring bar with the first convex contouring bar by the second actuator, creating the cylindrically curved bulge in the transparent window that is suctioned to the channel; andAtty. Docket No.: BMFP-101-A-WO moving the concave contouring bar between the first longitudinal edge of the opening and the second longitudinal edge of the opening by the second actuator, causing the select portions of the layer of resin to detach from the transparent window.

17. The method of claim 16, further comprising: applying a lubricant between the surface of the transparent window that faces toward the image projection system and the channel.

18. The method of any one of claims 16 to 17, wherein: the channel comprises an elastomer.

19. A method of using the 3D printing system of any one of claims 2 to 3, claim 6, claim 7, or claims 10 to 13, comprising: exposing a layer of resin between the transparent window and the printing platform to light from the image projection system, causing select portions of the resin to cure; vertically moving the printing platform a layer-thickness distance away from the image projection system by the first actuator; superimposing the concave contouring bar with the first convex contouring bar by the second actuator, creating the cylindrically curved bulge in the transparent window that is suctioned to the channel; moving the concave contouring bar between the first longitudinal edge of the opening and a second longitudinal edge of the opening by the second actuator, causing the select portions of the layer of resin to detach from the transparent window; and superimposing the concave contouring bar with the second convex contouring bar by the second actuator, recreating the cylindrically curved bulge in the transparent window that is suctioned to the channel.

20. The method of claim 19, further comprising: applying a lubricant between the surface of the transparent window that faces toward the image projection system and the channel.

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