DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claim Objections
Claims 1, 9 and 15 are objected to because of the following informalities:
The phrase “…the first beam unit configured scan over…” present in all claims, the word “to” is missing between the words “configured” and “scan”.
In claim 15, the claim language lacks proper antecedent basis for the phrase “the computer readable storage unit”. The claim introduces “A computer readable storage medium” but not “the computer readable storage unit”.
Appropriate correction is required.
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 1, 9 and 15 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
The claim language “… for N-1 layers…” in the phrase “… for N-1 layers the first end(n) and the second end(n) are offset with respect to each other along the seam(n) to define a Y-offset along the seam(n), the offset varying over the sequence of N selectively fused powder layers” may be interpreted in plain language to mean “apply a Y-offset to all (N) but one (-1) layer”, which introduces the ambiguity of which layer may not have the offset, e.g. the top layer, the bottom layer, or a random layer in between. This phrase opens the claim to multiple interpretations, thus rendering the claim indefinite.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 1-20 are rejected under 35 U.S.C. 103 as being unpatentable over Plas et al., EP Patent Application Publication No. 3722075 A1 in view of Crear et al., US Patent Application Publication No. 20170203517 A1.
Claim 1. Plas discloses a three-dimensional (3D) printing system for forming a 3D article comprising: (Plas, Abstract “A system for fabricating a three-dimensional article (2)…”)
a print engine including a motorized build plate, (Plas, [0013] “System 2 includes a build module 6 having a motorized platform 8. The motorized platform 8 has a support surface 10 upon which the three-dimensional article 4 is formed.”)
a coater, and (Plas, Abstract “… includes a powder dispenser (14)…”)
a plurality of beam units at least including a first beam unit and a second beam unit, (Plas, Abstract “The fusing apparatus is configured to generate and scan a plurality of beams (18) across a build plane including a first beam and a second beam.”)
the coater configured to coat a layer of fusible powder over the motorized build plate to span a build plane, (Plas, col 4 line 19 “… a powder dispenser 14 to dispense a layer of powder 15 onto the upper surface 12.”; and col 4 line 55 “… ‘build plane’ 19 which is generally proximate to the upper surface 12 of the dispensed powder 15.”)
the first beam unit configured scan over a first lateral region of the build plane, the second beam unit configured to scan over a second lateral region of the build plane, (Plas, col 4 line 53 “The fusing apparatus 16 is configured to scan the energy beams over a laterally extending ‘build plane’ 19…”; and col 2 line 24 “The fusing apparatus is configured to generate and scan a plurality of beams across a build plane including a first beam and a second beam.”)
the first and second lateral regions overlap over an overlap zone; (Plas, col 1 line 51 “… a seam along which the first and second areas overlap.”)
a controller configured to operate the motorized build plate, the coater, and the plurality of beam units to form the 3D article including forming a sequence of N selectively fused powder layers, N is at least 3, during forming the sequence of N selectively fused powder layers the controller is further configured to: (Plas, [0020] “The controller 20 is generally configured to perform the following operations: (1) position the motorized support with an upper surface 12 proximate to the build plane 19, (2) operate dispenser 14 to dispense a layer of powder, (3) operate the plurality of lasers 18 to selectively fuse portions of the dispensed layer of powder, and (4) repeat (1)-(3) to complete fabrication of the three-dimensional article 4.”; and col 2 line 27 “The controller is configured to operate the powder dispenser and the fusing apparatus to form a sequence of r selectively fused layers of powder in which r is at least 3.”; and col 7 line 1 “More generally, sequences can have r values of three or more. Sequences for r = 4, r = 5, r > 5, r > 10 are possible.”)
operate the first beam unit to selectively solidify a first sub-contour(n) having a first end(n) within the overlap zone; operate the second beam unit to selectively solidify a second sub-contour(n) having a second end(n) within the overlap zone; (Plas, col 1 line 52 “Fig. 4… The layers have been individually fused with a first energy beam fusing a first area, a second energy beam fusing a second area, and a seam along which the first and second areas overlap. The seams are laterally offset from layer to layer with a minimum offset distance u and a lateral span of v…”; and [0034] “Fig. 7… the concept of the seam 30 extends to contours… The inner contours 42 and 44 overlap along the seam 30.”)
the first end(n) and the second end(n) connect to form a seam(n) that is oriented along a lateral Y-axis; (Plas, col 2 line 35 “A lateral location of the seam varies layer by layer… over a zone having a lateral width of v.”; and Fig. 4 shows the seams oriented along axis T which corresponds to the claimed lateral Y-axis.)
Plas does not teach for N-1 layers the first end(n) and the second end(n) are offset with respect to each other along the seam(n) to define a Y-offset along the seam(n), the offset varying over the sequence of N selectively fused powder layers.
Crear teaches for N-1 layers the first end(n) and the second end(n) are offset with respect to each other along the seam(n) to define a Y-offset along the seam(n), the offset varying over the sequence of N selectively fused powder layers. (Crear, [0034] “Referring to FIGS. 5 and 8, in S14, a dimension (Dx and/or Dy) of an offset step 200 and/or 202 created between first plurality of layers 184 and second plurality of layers 190 in outer surface 192 of test structure 180 is/are measured”; [0035] “For example, an X-direction misalignment (Dx) of 0.1 millimeters, would be used to adjust calibrated laser(s) 134, 136 0.1 mm in the X-direction in such a way to remove the misalignment… For example, in terms of 2 corrections being applied, X-direction dimension Dx of X-direction offset step 200 may be applied as a first alignment correction 111 (FIG. 4) to a selected one of pair of calibrated lasers 134, 136 for a given overlap region 182, and Y-direction dimension Dy of Y-direction offset step 202 may be applied as a second alignment correction 111 (FIG. 4) to the same selected one of pair of calibrated lasers 134, 136 for the same overlap region 182.”)
Plas and Crear are analogous art because they are related to 3D laser printing. Although Crear teaches the correction of misalignment in a given layer, in order to correct the misalignment in the x or y direction, the system must have inherent control over the x and y position of the lasers and may be programmed to introduce misalignment intentionally. Crear teaches that one approach to address the causes of alignment inaccuracies leading to an offset in the x or y direction is applying alignment correction randomization. “Alignment correction randomization works within the laser overlap region (region where multiple lasers can work on the same part on any given layer) by randomizing where each laser starts and stops within the overlapping area preventing the visualization of a single discrete starting and stopping point for each laser along the vertical (Z) axis of the part.” (Crear, [0006])
Accordingly, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to apply the known technique of alignment correction randomization to a device with a multi-axial control such as a 3D printer disclosed by Plas so that seam offsets may be applied not only in the x-direction but also the y-direction. Doing so would yield the predictable result of further distributing the seam artifacts along the vertical axis, decreasing the visualization of the imperfections from alignment inaccuracies as taught by Crear.
Claim 2. Modified Plas discloses the three-dimensional (3D) printing system of claim 1 wherein the seam(n) has a varying location with respect to a lateral X-axis over a sequence of M selectively fused powder layers, the lateral X-axis is perpendicular to the lateral Y-axis, M is at least 3. (Plas, [0023] “Figs. 3A-D are illustrations depicting a deposition and fusion sequence of powder layers having a seam 30 having a transverse location that varies from layer to layer.”; and col 7 line 1 “More generally, sequences can have r values of three or more. Sequences for r = 4, r = 5, r > 5, r > 10 are possible.”)
Claim 3. Modified Plas discloses the three-dimensional (3D) printing system of claim 1 wherein the print engine includes a gas handling system configured to flow a non-oxidizing gas generally along the Y-axis during operation of the first and second beam units. (Crear, [0028] “Processing chamber 130 is filled with an inert gas such as argon or nitrogen and controlled to minimize or eliminate oxygen. Control system 104 is configured to control a flow of a gas mixture 160 within processing chamber 130 from a source of inert gas 154.”)
Although Crear discloses the use of inert gas, under Broadest Reasonable Interpretation, the term “non-oxidizing gas” encompasses any gas used to prevent oxidation of the weld pool. Inert gas is defined as “any of the unreactive gaseous elements; any gas… that is nonoxidizing” (dictionary.com). Therefore, it would have been obvious to one of ordinary skill in the art to modify Plas to include the inert or noble gas disclosed by Crear for its nonoxidizing nature to prevent the oxidation of the weld pool.
Claim 4. Modified Plas discloses the three-dimensional (3D) printing system of claim 1 wherein within the sequence of N layers any two different layers have a difference in Y-offset of at least 5 microns. (Crear, [0034] “The dimension(s) Dx, Dy may be measured in any desired units, e.g., micrometers, millimeters, etc.”; and [0036] “That is, each overlap region 182A-E may have a corresponding alignment correction(s) 111 (FIG. 4), e.g., X-direction and/or Y-direction. In one embodiment, a standard deviation of less than a predetermined threshold, e.g., 30 micrometers, across test structures 180A-E is sought to ensure accuracy for all objects created using system 100.”)
Although Crear teaches different corresponding alignment corrections restricted by a standard deviation across test structures 180A-E instead of the claimed “any two different layers (within the sequence of N layers) have a difference in Y-offset”, achieving a meaningful standard deviation threshold inherently means the misalignment in the overlap regions 182A-E between each test structure must be different from each other.
Accordingly, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to apply this alignment correction restricted by a standard deviation as taught by Crear to the 3D printing system disclosed by Plas. One of ordinary skill in the art would have been motivated to apply this technique because as it “ensures accuracy for all objects created using the system” (Crear, [0036]) it also may be used to ensure accuracy for all layers within one structure.
Furthermore, a standard deviation of 30 micrometers disclosed by Crear may include differences of “at least 5 microns” as claimed, and it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only ordinary skill in the art. In re Aller, 105 USPQ 233.
Claim 5. Modified Plas discloses the three-dimensional (3D) printing system of claim 4 wherein the first beam unit and the second beam unit have a relative alignment uncertainty AY along the Y-axis, (Plas, [0007] “…the transverse overlap distance (x) is based upon an alignment uncertainty of the first beam with respect to the second beam along a transverse axis that is transverse to the seam.”)
the Y-offset is no more than 50% of AY. (Crear, [0035] “For example, an X-direction misalignment (Dx) of 0.1 millimeters, would be used to adjust calibrated laser(s) 134, 136 0.1 mm in the X-direction in such a way to remove the misalignment… For example, in terms of 2 corrections being applied, X-direction dimension Dx of X-direction offset step 200 may be applied as a first alignment correction 111 (FIG. 4) to a selected one of pair of calibrated lasers 134, 136 for a given overlap region 182, and Y-direction dimension Dy of Y-direction offset step 202 may be applied as a second alignment correction 111 (FIG. 4) to the same selected one of pair of calibrated lasers 134, 136 for the same overlap region 182”; and [0036] “In one embodiment, a standard deviation of less than a predetermined threshold, e.g., 30 micrometers, across test structures 180A-E is sought to ensure accuracy for all objects created using system 100.”)
Crear teaches a method for aligning calibrated lasers of a laser additive manufacturing system where one embodiment ensures accuracy by applying alignment correction with a given standard deviation. It would have been an obvious matter of design choice to similarly restrict the Dy misalignment disclosed by Crear, which corresponds to the claimed Y-offset, with a selection of a specific, arbitrary value such as “50% of AY (the alignment uncertainty along the Y-axis)”, since the applicant has not disclosed that limiting the Y-offset to 50% of AY solves any problem or is for a particular reason. It appears that the claimed invention would perform equally well with restricting the Dy misalignment/Y-offset with “50% of AY”.
Claim 6. Modified Plas discloses the three-dimensional (3D) printing system of claim 4 wherein scanning of the beam units defines a melt pool width W, (Crear, [0005] “Typically, each laser is individually calibrated so a known offset correction can be applied for each laser, allowing the precise location of the operational field of each laser to be known. In these type machines, as shown in the schematic plan view of FIG. 1, each laser has a field 10, 12 upon which it can create a melt pool on the metal powder on a build platform.”)
the Y-offset is no more than 50% of the melt pool width W. (Crear, [0035] “For example, an X-direction misalignment (Dx) of 0.1 millimeters, would be used to adjust calibrated laser(s) 134, 136 0.1 mm in the X-direction in such a way to remove the misalignment… For example, in terms of 2 corrections being applied, X-direction dimension Dx of X-direction offset step 200 may be applied as a first alignment correction 111 (FIG. 4) to a selected one of pair of calibrated lasers 134, 136 for a given overlap region 182, and Y-direction dimension Dy of Y-direction offset step 202 may be applied as a second alignment correction 111 (FIG. 4) to the same selected one of pair of calibrated lasers 134, 136 for the same overlap region 182”; and [0036] “In one embodiment, a standard deviation of less than a predetermined threshold, e.g., 30 micrometers, across test structures 180A-E is sought to ensure accuracy for all objects created using system 100.”)
Crear teaches a method for aligning calibrated lasers of a laser additive manufacturing system where one embodiment ensures accuracy by applying alignment correction with a given standard deviation. It would have been an obvious matter of design choice to similarly restrict the Dy misalignment disclosed by Crear, which corresponds to the claimed Y-offset, with a selection of a specific, arbitrary value such as “50% of the melt pool width W”, since the applicant has not disclosed that limiting the Y-offset to 50% of the melt pool width W solves any problem or is for a particular reason. It appears that the claimed invention would perform equally well with restricting the Dy misalignment/Y-offset with “50% of the melt pool width W”.
Claim 7. Modified Plas discloses the three-dimensional (3D) printing system of claim 1 wherein N is at least 4. (Plas, col 7 line 1 “More generally, sequences can have r values of three or more. Sequences for r = 4, r = 5, r > 5, r > 10 are possible.”)
Claim 8. Modified Plas discloses the three-dimensional (3D) printing system of claim 1 wherein N is at least 5. (Plas, col 7 line 1 “More generally, sequences can have r values of three or more. Sequences for r = 4, r = 5, r > 5, r > 10 are possible.”)
Claim 9. Plas discloses a method for forming a three-dimensional (3D) article comprising: (Plas, Abstract “A system for fabricating a three-dimensional article (2)…”)
providing a print engine including a motorized build plate, (Plas, [0013] “System 2 includes a build module 6 having a motorized platform 8. The motorized platform 8 has a support surface 10 upon which the three-dimensional article 4 is formed.”)
a coater, and (Plas, Abstract “… includes a powder dispenser (14)…”)
a plurality of beam units including (Plas, Abstract “The fusing apparatus is configured to generate and scan a plurality of beams (18) across a build plane including a first beam and a second beam.”)
the coater configured to coat a layer of fusible powder over the motorized build plate to span a build plane, (Plas, col 4 line 19 “… a powder dispenser 14 to dispense a layer of powder 15 onto the upper surface 12.”; and col 4 line 55 “… ‘build plane’ 19 which is generally proximate to the upper surface 12 of the dispensed powder 15.”)
the first beam unit configured scan over a first lateral region of the build plane, the second beam unit configured to scan over a second lateral region of the build plane, (Plas, col 4 line 53 “The fusing apparatus 16 is configured to scan the energy beams over a laterally extending ‘build plane’ 19…”; and col 2 line 24 “The fusing apparatus is configured to generate and scan a plurality of beams across a build plane including a first beam and a second beam.”)
the first and second lateral regions overlap over an overlap zone; (Plas, col 1 line 51 “… a seam along which the first and second areas overlap.”)
operating the first beam unit to selectively solidify a first sub-contour(n) having a first end(n) within the overlap zone; operating the second beam unit to selectively solidify a second sub-contour(n) having a second end(n) within the overlap zone; (Plas, col 1 line 52 “Fig. 4… The layers have been individually fused with a first energy beam fusing a first area, a second energy beam fusing a second area, and a seam along which the first and second areas overlap. The seams are laterally offset from layer to layer with a minimum offset distance u and a lateral span of v…”; and [0034] “Fig. 7… the concept of the seam 30 extends to contours… The inner contours 42 and 44 overlap along the seam 30.”)
the first end(n) and the second end(n) connect to form a seam(n) that is oriented along a lateral Y-axis; (Plas, col 2 line 35 “A lateral location of the seam varies layer by layer… over a zone having a lateral width of v.”; and Fig. 4 shows the seams oriented along axis T which corresponds to the claimed lateral Y-axis.)
Plas does not teach for N-1 layers the first end(n) and the second end(n) are offset with respect to each other along the seam(n) to define a Y-offset along the seam(n), the offset varying over the sequence of N selectively fused powder layers.
Crear teaches for N-1 layers the first end(n) and the second end(n) are offset with respect to each other along the seam(n) to define a Y-offset, the Y-offset varying over the sequence of N selectively fused powder layers. (Crear, [0034] “Referring to FIGS. 5 and 8, in S14, a dimension (Dx and/or Dy) of an offset step 200 and/or 202 created between first plurality of layers 184 and second plurality of layers 190 in outer surface 192 of test structure 180 is/are measured”; [0035] “For example, an X-direction misalignment (Dx) of 0.1 millimeters, would be used to adjust calibrated laser(s) 134, 136 0.1 mm in the X-direction in such a way to remove the misalignment… For example, in terms of 2 corrections being applied, X-direction dimension Dx of X-direction offset step 200 may be applied as a first alignment correction 111 (FIG. 4) to a selected one of pair of calibrated lasers 134, 136 for a given overlap region 182, and Y-direction dimension Dy of Y-direction offset step 202 may be applied as a second alignment correction 111 (FIG. 4) to the same selected one of pair of calibrated lasers 134, 136 for the same overlap region 182.”)
Plas and Crear are analogous art because they are related to 3D laser printing. Although Crear teaches the correction of misalignment in a given layer, in order to correct the misalignment in the x or y direction, the system must have inherent control over the x and y position of the lasers and may be programmed to introduce misalignment intentionally. Crear teaches that one approach to address the causes of alignment inaccuracies leading to an offset in the x or y direction is applying alignment correction randomization. “Alignment correction randomization works within the laser overlap region (region where multiple lasers can work on the same part on any given layer) by randomizing where each laser starts and stops within the overlapping area preventing the visualization of a single discrete starting and stopping point for each laser along the vertical (Z) axis of the part.” (Crear, [0006])
Accordingly, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to apply the known technique of alignment correction randomization to a device with a multi-axial control such as a 3D printer disclosed by Plas so that seam offsets may be applied not only in the x-direction but also the y-direction. Doing so would yield the predictable result of further distributing the seam artifacts along the vertical axis, decreasing the visualization of the imperfections from alignment inaccuracies as taught by Crear.
Claim 10. Modified Plas discloses the method of claim 9 wherein the seam(n) has a varying location with respect to a lateral X-axis over a sequence of M selectively fused powder layers, the lateral X-axis is perpendicular to the lateral Y-axis, M is at least 3. (Plas, [0023] “Figs. 3A-D are illustrations depicting a deposition and fusion sequence of powder layers having a seam 30 having a transverse location that varies from layer to layer.”; and col 7 line 1 “More generally, sequences can have r values of three or more. Sequences for r = 4, r = 5, r > 5, r > 10 are possible.”)
Claim 11. Modified Plas discloses the method of claim 9 wherein the print engine includes a gas handling system configured to flow a non-oxidizing gas generally along the Y-axis during operation of the first and second beam units. (Crear, [0028] “Processing chamber 130 is filled with an inert gas such as argon or nitrogen and controlled to minimize or eliminate oxygen. Control system 104 is configured to control a flow of a gas mixture 160 within processing chamber 130 from a source of inert gas 154.”)
Although Crear discloses the use of inert gas, under Broadest Reasonable Interpretation, the term “non-oxidizing gas” encompasses any gas used to prevent oxidation of the weld pool. Inert gas is defined as “any of the unreactive gaseous elements; any gas… that is nonoxidizing” (dictionary.com). Therefore, it would have been obvious to one of ordinary skill in the art to modify Plas to include the inert or noble gas disclosed by Crear for its nonoxidizing nature to prevent the oxidation of the weld pool.
Claim 12. Modified Plas discloses the method of claim 9 wherein within the sequence of N layers any two different layers have a difference in Y-offset of at least 5 microns. (Crear, [0034] “The dimension(s) Dx, Dy may be measured in any desired units, e.g., micrometers, millimeters, etc.”; and [0036] “That is, each overlap region 182A-E may have a corresponding alignment correction(s) 111 (FIG. 4), e.g., X-direction and/or Y-direction. In one embodiment, a standard deviation of less than a predetermined threshold, e.g., 30 micrometers, across test structures 180A-E is sought to ensure accuracy for all objects created using system 100.”)
Although Crear teaches different corresponding alignment corrections restricted by a standard deviation across test structures 180A-E instead of the claimed “any two different layers (within the sequence of N layers) have a difference in Y-offset”, achieving a meaningful standard deviation threshold inherently means the misalignment in the overlap regions 182A-E between each test structure must be different from each other.
Accordingly, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to apply this alignment correction restricted by a standard deviation as taught by Crear to the 3D printing system disclosed by Plas. One of ordinary skill in the art would have been motivated to apply this technique because as it “ensures accuracy for all objects created using the system” (Crear, [0036]) it also may be used to ensure accuracy for all layers within one structure.
Furthermore, a standard deviation of 30 micrometers disclosed by Crear may include differences of “at least 5 microns” as claimed, and it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only ordinary skill in the art. In re Aller, 105 USPQ 233.
Claim 13. Modified Plas discloses the method of claim 9 wherein the first beam unit and the second beam unit have a relative alignment uncertainty AY along the Y-axis, (Plas, [0007] “…the transverse overlap distance (x) is based upon an alignment uncertainty of the first beam with respect to the second beam along a transverse axis that is transverse to the seam.”)
the Y-offset is no more than 50% of AY. (Crear, [0035] “For example, an X-direction misalignment (Dx) of 0.1 millimeters, would be used to adjust calibrated laser(s) 134, 136 0.1 mm in the X-direction in such a way to remove the misalignment… For example, in terms of 2 corrections being applied, X-direction dimension Dx of X-direction offset step 200 may be applied as a first alignment correction 111 (FIG. 4) to a selected one of pair of calibrated lasers 134, 136 for a given overlap region 182, and Y-direction dimension Dy of Y-direction offset step 202 may be applied as a second alignment correction 111 (FIG. 4) to the same selected one of pair of calibrated lasers 134, 136 for the same overlap region 182”; and [0036] “In one embodiment, a standard deviation of less than a predetermined threshold, e.g., 30 micrometers, across test structures 180A-E is sought to ensure accuracy for all objects created using system 100.”)
Crear teaches a method for aligning calibrated lasers of a laser additive manufacturing system where one embodiment ensures accuracy by applying alignment correction with a given standard deviation. It would have been an obvious matter of design choice to similarly restrict the Dy misalignment disclosed by Crear, which corresponds to the claimed Y-offset, with a selection of a specific, arbitrary value such as “50% of AY (the alignment uncertainty along the Y-axis)”, since the applicant has not disclosed that limiting the Y-offset to 50% of AY solves any problem or is for a particular reason. It appears that the claimed invention would perform equally well with restricting the Dy misalignment/Y-offset with “50% of AY”.
Claim 14. The method of claim 9 wherein N is at least 5. (Plas, col 7 line 1 “More generally, sequences can have r values of three or more. Sequences for r = 4, r = 5, r > 5, r > 10 are possible.”)
Claim 15. Plas discloses a computer readable storage medium for operating a three dimensional (3D) printing system, the printing system including: (Plas, Abstract “A system for fabricating a three-dimensional article (2)… The controller (20) is configured to operate the powder dispenser and the fusing apparatus…”; and col 5 line 22 “The controller 20 includes a processor coupled to a computer-readable storage apparatus.”)
a print engine including a motorized build plate, a coater, and (Plas, [0013] “System 2 includes a build module 6 having a motorized platform 8. The motorized platform 8 has a support surface 10 upon which the three-dimensional article 4 is formed.”)
a plurality of beam units at least including a first beam unit and a second beam unit, (Plas, Abstract “The fusing apparatus is configured to generate and scan a plurality of beams (18) across a build plane including a first beam and a second beam.”)
the coater configured to coat a layer of fusible powder over the motorized build plate to span a build plane, (Plas, col 4 line 19 “… a powder dispenser 14 to dispense a layer of powder 15 onto the upper surface 12.”; and col 4 line 55 “… ‘build plane’ 19 which is generally proximate to the upper surface 12 of the dispensed powder 15.”)
the first beam unit configured scan over a first lateral region of the build plane, the second beam unit configured to scan over a second lateral region of the build plane, (Plas, col 4 line 53 “The fusing apparatus 16 is configured to scan the energy beams over a laterally extending ‘build plane’ 19…”; and col 2 line 24 “The fusing apparatus is configured to generate and scan a plurality of beams across a build plane including a first beam and a second beam.”)
the first and second lateral regions overlap over an overlap zone; and (Plas, col 1 line 51 “… a seam along which the first and second areas overlap.”)
a controller, (Plas, [0018] “The motorized platform 8, the powder dispenser 14, and the fusing apparatus 16 are all under control of a controller 20.”)
the computer readable storage unit being non-transitory and storing software instructions that in response to execution by a processor operate the motorized build plate, (Plas, col 5 line 26 “When executed by the processor, the software instructions control various portions of system 2 including the motorized platform 8, the powder dispenser 14, and the fusing apparatus 16.”)
the coater, and (Plas, Abstract “… includes a powder dispenser (14)…”)
the plurality of beam units to at least: (Plas, Abstract “The fusing apparatus is configured to generate and scan a plurality of beams (18) across a build plane…”)
form the 3D article including forming a sequence of N selectively fused powder layers, N is at least 3, during forming the sequence of N selectively fused powder layers performing operations including: (Plas, [0020] “The controller 20 is generally configured to perform the following operations: (1) position the motorized support with an upper surface 12 proximate to the build plane 19, (2) operate dispenser 14 to dispense a layer of powder, (3) operate the plurality of lasers 18 to selectively fuse portions of the dispensed layer of powder and (4) repeat (1)-(3) to complete fabrication of the three dimensional article 4.”)
operate the first beam unit to selectively solidify a first sub-contour(n) having a first end(n) within the overlap zone; operate the second beam unit to selectively solidify a second sub-contour(n) having a second end(n) within the overlap zone; (Plas, col 1 line 52 “Fig. 4… The layers have been individually fused with a first energy beam fusing a first area, a second energy beam fusing a second area, and a seam along which the first and second areas overlap. The seams are laterally offset from layer to layer with a minimum offset distance u and a lateral span of v…”; and [0034] “Fig. 7… the concept of the seam 30 extends to contours… The inner contours 42 and 44 overlap along the seam 30.”)
the first end(n) and the second end(n) connect to form a seam(n) that is oriented along a lateral Y-axis; (Plas, col 2 line 35 “A lateral location of the seam varies layer by layer… over a zone having a lateral width of v.”; and Fig. 4 shows the seams oriented along axis T which corresponds to the claimed lateral Y-axis.)
Plas does not teach for N-1 layers the first end(n) and the second end(n) are offset with respect to each other along the seam(n) to define a Y-offset along the seam(n), the offset varying over the sequence of N selectively fused powder layers.
Crear teaches for N-1 layers the first end(n) and the second end(n) are offset with respect to each other along the seam(n) to define a Y-offset, the Y-offset varying over the sequence of N selectively fused powder layers. (Crear, [0034] “Referring to FIGS. 5 and 8, in S14, a dimension (Dx and/or Dy) of an offset step 200 and/or 202 created between first plurality of layers 184 and second plurality of layers 190 in outer surface 192 of test structure 180 is/are measured”; [0035] “For example, an X-direction misalignment (Dx) of 0.1 millimeters, would be used to adjust calibrated laser(s) 134, 136 0.1 mm in the X-direction in such a way to remove the misalignment… For example, in terms of 2 corrections being applied, X-direction dimension Dx of X-direction offset step 200 may be applied as a first alignment correction 111 (FIG. 4) to a selected one of pair of calibrated lasers 134, 136 for a given overlap region 182, and Y-direction dimension Dy of Y-direction offset step 202 may be applied as a second alignment correction 111 (FIG. 4) to the same selected one of pair of calibrated lasers 134, 136 for the same overlap region 182.”)
Plas and Crear are analogous art because they are related to 3D laser printing. Although Crear teaches the correction of misalignment in a given layer, in order to correct the misalignment in the x or y direction, the system must have inherent control over the x and y position of the lasers and may be programmed to introduce misalignment intentionally. Crear teaches that one approach to address the causes of alignment inaccuracies leading to an offset in the x or y direction is applying alignment correction randomization. “Alignment correction randomization works within the laser overlap region (region where multiple lasers can work on the same part on any given layer) by randomizing where each laser starts and stops within the overlapping area preventing the visualization of a single discrete starting and stopping point for each laser along the vertical (Z) axis of the part.” (Crear, [0006])
Accordingly, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to apply the known technique of alignment correction randomization to a device with a multi-axial control such as a 3D printer disclosed by Plas so that seam offsets may be applied not only in the x-direction but also the y-direction. Doing so would yield the predictable result of further distributing the seam artifacts along the vertical axis, decreasing the visualization of the imperfections from alignment inaccuracies as taught by Crear.
Claim 16. The computer readable storage unit of claim 15 wherein the seam(n) has a varying location with respect to a lateral X-axis over a sequence of M selectively fused powder layers, the lateral X-axis is perpendicular to the lateral Y-axis, M is at least 3. (Plas, [0023] “Figs. 3A-D are illustrations depicting a deposition and fusion sequence of powder layers having a seam 30 having a transverse location that varies from layer to layer.”; and col 7 line 1 “More generally, sequences can have r values of three or more. Sequences for r = 4, r = 5, r > 5, r > 10 are possible.”)
Claim 17. The computer readable storage unit of claim 15 wherein the print engine includes a gas handling system configured to flow a non-oxidizing gas generally along the Y-axis during operation of the first and second beam units. (Crear, [0028] “Processing chamber 130 is filled with an inert gas such as argon or nitrogen and controlled to minimize or eliminate oxygen. Control system 104 is configured to control a flow of a gas mixture 160 within processing chamber 130 from a source of inert gas 154.”)
Although Crear discloses the use of inert gas, under Broadest Reasonable Interpretation, the term “non-oxidizing gas” encompasses any gas used to prevent oxidation of the weld pool. Inert gas is defined as “any of the unreactive gaseous elements; any gas… that is nonoxidizing” (dictionary.com). Therefore, it would have been obvious to one of ordinary skill in the art to modify Plas to include the inert or noble gas disclosed by Crear for its nonoxidizing nature to prevent the oxidation of the weld pool.
Claim 18. The computer readable storage unit of claim 15 wherein within the sequence of N layers any two different layers have a difference in Y-offset along the Y-axis between seam locations of at least 5 microns. (Crear, [0034] “The dimension(s) Dx, Dy may be measured in any desired units, e.g., micrometers, millimeters, etc.”; and [0036] “That is, each overlap region 182A-E may have a corresponding alignment correction(s) 111 (FIG. 4), e.g., X-direction and/or Y-direction. In one embodiment, a standard deviation of less than a predetermined threshold, e.g., 30 micrometers, across test structures 180A-E is sought to ensure accuracy for all objects created using system 100.”)
Although Crear teaches different corresponding alignment corrections restricted by a standard deviation across test structures 180A-E instead of the claimed “any two different layers (within the sequence of N layers) have a difference in Y-offset”, achieving a meaningful standard deviation threshold inherently means the misalignment in the overlap regions 182A-E between each test structure must be different from each other.
Accordingly, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to apply this alignment correction restricted by a standard deviation as taught by Crear to the 3D printing system disclosed by Plas. One of ordinary skill in the art would have been motivated to apply this technique because as it “ensures accuracy for all objects created using the system” (Crear, [0036]) it also may be used to ensure accuracy for all layers within one structure.
Furthermore, a standard deviation of 30 micrometers disclosed by Crear may include differences of “at least 5 microns” as claimed, and it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only ordinary skill in the art. In re Aller, 105 USPQ 233.
Claim 19. The computer readable storage unit of claim 15 wherein the first beam unit and the second beam unit have a relative alignment uncertainty AY along the Y-axis, (Plas, [0007] “…the transverse overlap distance (x) is based upon an alignment uncertainty of the first beam with respect to the second beam along a transverse axis that is transverse to the seam.”)
the Y- offset is no more than 50% of AY. (Crear, [0035] “For example, an X-direction misalignment (Dx) of 0.1 millimeters, would be used to adjust calibrated laser(s) 134, 136 0.1 mm in the X-direction in such a way to remove the misalignment… For example, in terms of 2 corrections being applied, X-direction dimension Dx of X-direction offset step 200 may be applied as a first alignment correction 111 (FIG. 4) to a selected one of pair of calibrated lasers 134, 136 for a given overlap region 182, and Y-direction dimension Dy of Y-direction offset step 202 may be applied as a second alignment correction 111 (FIG. 4) to the same selected one of pair of calibrated lasers 134, 136 for the same overlap region 182”; and [0036] “In one embodiment, a standard deviation of less than a predetermined threshold, e.g., 30 micrometers, across test structures 180A-E is sought to ensure accuracy for all objects created using system 100.”)
Crear teaches a method for aligning calibrated lasers of a laser additive manufacturing system where one embodiment ensures accuracy by applying alignment correction with a given standard deviation. It would have been an obvious matter of design choice to similarly restrict the Dy misalignment disclosed by Crear, which corresponds to the claimed Y-offset, with a selection of a specific, arbitrary value such as “50% of AY (the alignment uncertainty along the Y-axis)”, since the applicant has not disclosed that limiting the Y-offset to 50% of AY solves any problem or is for a particular reason. It appears that the claimed invention would perform equally well with restricting the Dy misalignment/Y-offset with “50% of AY”.
Claim 20. The computer readable storage unit of claim 15 wherein N is at least 5. (Plas, col 7 line 1 “More generally, sequences can have r values of three or more. Sequences for r = 4, r = 5, r > 5, r > 10 are possible.”)
Conclusion
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/K.B.M./Examiner, Art Unit 3761
/STEVEN W CRABB/Supervisory Patent Examiner, Art Unit 3761