Luxcreo Inc v. Carbon Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: LuxCreo Inc. (Delaware)
  • Defendant: Carbon, Inc. (Delaware)
  • Plaintiff's Counsel: Rimon, P.C.
• Case Identification: 3:26-cv-01635, N.D. Cal., 07/17/2026
• Venue Allegations: Venue is alleged to be proper as Defendant maintains its principal place of business in the district (Redwood City, CA) and because a substantial part of the events giving rise to the action, including cease-and-desist letters, occurred in the district.
• Core Dispute: Plaintiff LuxCreo seeks a declaratory judgment that its 3D printing systems and resins do not infringe seventeen of Defendant Carbon's patents, and that those patents are invalid and/or unenforceable due to inequitable conduct.
• Technical Context: The dispute centers on advanced additive manufacturing, specifically Continuous Liquid Interphase Printing (CLIP) and dual-cure photopolymer resins, which enable faster production speeds and stronger end-use parts compared to traditional 3D printing methods.
• Key Procedural History: The action was precipitated by a series of letters from Carbon's counsel sent between October 2025 and June 2026, accusing LuxCreo of infringing numerous patents and demanding it cease all allegedly infringing activities. A central pillar of LuxCreo's complaint is the allegation of inequitable conduct during the prosecution of several patents, asserting that Carbon's founders and attorneys intentionally withheld highly material prior art from the U.S. Patent and Trademark Office.

Case Timeline

Date	Event
2005-11-09	Rolland '133 Publication (alleged prior art) filed
2012-04-17	'728 Patent (alleged prior art) issued
2013-02-12	Earliest Priority Date for CLIP Patent Family (e.g., '601, '181, '938)
2014-06-23	Earliest Priority Date for Dual Cure Patent Family (e.g., '142, '963)
2015-12-08	'601 Patent issued
2016-09-27	'142 Patent issued
2016-11-22	'920 Patent issued
2017-03-21	'606 Patent issued
2017-06-13	'963 Patent issued
2018-05-29	'164 Patent issued
2018-07-10	'938 Patent issued
2018-12-04	'181 Patent issued
2019-03-26	'066 Patent issued
2019-11-12	'699 Patent issued
2020-05-12	'880 Patent issued
2020-10-06	'856 Patent issued
2021-01-26	'868 Patent issued
2022-02-01	'516 Patent issued
2022-06-14	'342 Patent issued
2024-11-26	'073 Patent issued
2025-10-25	First infringement notice letter from Carbon to LuxCreo
2025-03-21	Second infringement notice letter from Carbon to LuxCreo
2025-12-12	Third infringement notice letter from Carbon to LuxCreo
2026-05-19	'895 Patent issued
2026-06-11	Infringement notice email from Carbon's counsel to LuxCreo
2026-07-17	Complaint for Declaratory Judgment filed

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 9,205,601 - "Continuous liquid interphase printing,"

• Patent Identification: U.S. Patent No. 9,205,601, "Continuous liquid interphase printing," issued December 8, 2015 Compl. ¶ 51

The Invention Explained

• Problem Addressed: Conventional "bottom-up" stereolithography (3D printing) is a slow, layer-by-layer process that requires mechanical separation of the newly formed solid layer from the build window, which limits speed and can introduce structural weaknesses or "stair-step" artifacts into the final product Compl. ¶ 6 '601 Patent, col. 1:21-48
• The Patented Solution: The patent describes a method called Continuous Liquid Interphase Printing (CLIP) that overcomes these limitations. It uses an oxygen-permeable build window to create a persistent liquid "dead zone" at the interface between the window and the photopolymerizable resin. This uncured liquid layer prevents the newly formed solid part from adhering to the window, allowing the part to be "grown" continuously as the carrier lifts it from the resin bath, rather than being printed in discrete steps '601 Patent, abstract '601 Patent, col. 2:13-33
• Technical Importance: The CLIP process represented a significant increase in 3D printing speed and produced parts with isotropic properties, making the technology more viable for manufacturing end-use parts rather than just prototypes Compl. ¶ 42

Key Claims at a Glance

• The complaint alleges non-infringement of one or more claims of the '601 Patent, with Claim 1 being representative of the core method Compl. ¶ 56 Compl. ¶ 213
• The essential elements of independent method Claim 1 are:
  • Providing a carrier and an optically transparent member defining a build region.
  • Filling the build region with a polymerizable liquid.
  • Irradiating the build region through the transparent member to form a solid polymer.
  • Concurrently advancing the carrier away from the build surface.
  • Concurrently and continuously maintaining a "dead zone" of liquid in contact with the build surface.
  • Concurrently and continuously maintaining a "gradient of polymerization zone" between the dead zone and the solid polymer.
• The complaint notes that LuxCreo reserves the right to address all claims of the patent Compl. ¶ 56

U.S. Patent No. 9,453,142 - "Polyurethane resins having multiple mechanisms of hardening for use in producing three-dimensional objects,"

• Patent Identification: U.S. Patent No. 9,453,142, "Polyurethane resins having multiple mechanisms of hardening for use in producing three-dimensional objects," issued September 27, 2016 Compl. ¶ 58

The Invention Explained

• Problem Addressed: The complaint notes a general need for new additive manufacturing materials that can produce objects with sufficient structural and mechanical properties for end-use applications Compl. ¶ 42 '142 Patent, col. 2:22-26
• The Patented Solution: The '142 Patent discloses "dual cure" resins. These materials contain two separate reactive chemistries. The first is cured by light (photopolymerization) to rapidly form the object's shape in the 3D printer. The second is a latent chemistry (e.g., heat-activated) that is triggered after printing to achieve the final, robust mechanical properties. This two-stage process combines the speed of photopolymerization with the superior material properties of thermoset plastics '142 Patent, abstract '142 Patent, col. 3:4-31
• Technical Importance: Dual cure resins enabled the creation of 3D printed parts with a wide range of engineering-grade properties, such as high elasticity, tear strength, and durability, which were previously unattainable with standard 3D printing resins Compl. ¶¶41-42

Key Claims at a Glance

• The complaint alleges non-infringement of one or more claims, with Claim 1 being representative of the core chemical composition Compl. ¶ 62 Compl. ¶ 222
• The essential elements of independent claim 1 are a polymerizable liquid comprising a mixture of:
  • A reactive blocked prepolymer with a specific chemical structure (A-X-A).
  • A chain extender.
  • A reactive blocked diisocyanate.
• The complaint notes that LuxCreo reserves the right to address all claims of the patent Compl. ¶ 62

Multi-Patent Capsule: U.S. Patent No. 9,676,963

• Patent Identification: U.S. Patent No. 9,676,963 ("the '963 Patent"), "Methods of Producing Three-Dimensional Objects from Materials Having Multiple Mechanisms of Hardening," issued June 13, 2017 Compl. ¶ 76
• Technology Synopsis: The '963 Patent, part of the "Dual Cure" family, describes a method for creating a 3D object using a dual cure resin. The method involves a first cure with light to form an intermediate object, followed by a second cure, typically with heat or microwave radiation, to achieve final material properties '963 Patent, abstract
• Asserted Claims: Claim 1 (independent method claim) and its dependent claims are at issue Compl. ¶ 243
• Accused Features: Carbon has accused LuxCreo's dual-cure resins (e.g., EM+23) and the processes using them of infringement Compl. ¶¶18-24

Multi-Patent Capsule: U.S. Patent No. 10,647,880

• Patent Identification: U.S. Patent No. 10,647,880 ("the '880 Patent"), "Methods of Producing Polyurethane Three-Dimensional Objects from Materials Having Multiple Mechanisms of Hardening," issued May 12, 2020 Compl. ¶ 106
• Technology Synopsis: A member of the "Dual Cure" family, the '880 patent claims methods of forming a 3D object from a polyurethane, polyurea, or copolymer thereof. The method involves irradiating a build region containing a polymerizable liquid with light to form an intermediate, and then heating or microwave irradiating the intermediate to form the final object '880 Patent, abstract
• Asserted Claims: Claim 1 (independent method claim) and its dependent claims are at issue Compl. ¶ 477
• Accused Features: Carbon has accused LuxCreo's dual-cure resins and printing processes of infringement Compl. ¶¶18-24

Multi-Patent Capsule: U.S. Patent No. 12,629,895

• Patent Identification: U.S. Patent No. 12,629,895 ("the '895 Patent"), "Methods for Producing Three-Dimensional Objects," issued May 19, 2026 Compl. ¶ 148
• Technology Synopsis: The '895 patent is also a member of the "Dual Cure" family. It claims a method of forming a 3D object of polyurethane, polyurea, or copolymer by irradiating a build region containing a polymerizable liquid to form a scaffold, and then heating the intermediate to form the final object '895 Patent, abstract
• Asserted Claims: Claim 1 (independent method claim) and its dependent claims are at issue Compl. ¶ 985
• Accused Features: Carbon has accused LuxCreo's printers and resins, including products like the Asics ActiBreeze sandal, of infringement under this patent Compl. ¶ 26

III. The Accused Instrumentality

Product Identification

• The complaint seeks declaratory judgment of non-infringement for LuxCreo's products, which Defendant Carbon has accused. These include LuxCreo's 3D printers (Lux 3 and iLux series), its polymerizable resins (such as EM+23 resin), and final products made with this system, such as the "LuxCreo Insole," "Porsche Design 3D MTRX II Shoe," and "Asics ActiBreeze" footwear (Compl. ¶¶18; Compl. ¶ 21; Compl. ¶ 26).

Functionality and Market Context

• The complaint describes LuxCreo as a company that develops and sells systems for additive manufacturing, including for dental applications and footwear components Compl. ¶¶15-16
• The complaint does not provide a detailed technical breakdown of how the accused LuxCreo products operate. Instead, it frames the dispute by summarizing Carbon's accusations that these products utilize technologies covered by the Asserted Patents, such as continuous printing methods and dual-cure resins (Compl. ¶¶18; Compl. ¶ 21). LuxCreo's position is that its products do not practice the methods or contain the compositions claimed in Carbon's patents (Compl. ¶¶213; Compl. ¶ 222).

IV. Analysis of Infringement Allegations

The complaint, a declaratory judgment action, does not contain detailed infringement allegations or claim charts from the Plaintiff. Instead, it asserts non-infringement and focuses its technical arguments on the invalidity of the Defendant's patents. The complaint references infringement claim charts provided by Carbon's counsel in pre-suit letters, but those exhibits are not included with the complaint itself Compl. ¶ 21 Compl. ¶ 26 Therefore, a detailed infringement chart analysis based on the provided documents is not possible.

However, the complaint presents extensive and detailed arguments for the invalidity of several asserted patents based on prior art. For example, the complaint includes a detailed claim chart comparing claim 1 of the '963 patent to the disclosures of the '728 and '330 patents to support its invalidity argument (Compl. ¶ 382). This chart alleges that every element of the '963 patent's claim is disclosed in the prior art combination.

• Identified Points of Contention:
  • Scope Questions: A primary point of contention for the CLIP patents (like the '601 Patent) will be the interpretation of process-specific terms such as "continuously maintaining a dead zone" and "concurrently advancing." The court will need to determine if LuxCreo's process, whatever its specifics, falls within the scope of these terms as defined by the patent.
  • Technical Questions: For the dual-cure resin patents (like the '142 Patent), the dispute will likely involve a highly technical, chemical analysis. The core question will be whether the specific chemical compositions of LuxCreo's resins (e.g., the EM+23 resin) meet the precise structural formulas and component requirements recited in Carbon's claims Compl. ¶ 222

V. Key Claim Terms for Construction

• The Term: "continuously maintaining a dead zone" (from '601 Patent, Claim 1)

• Context and Importance: This phrase is the technological heart of the CLIP patents. Its construction will be critical in determining whether LuxCreo's printing process infringes. The dispute will likely center on what degree of "continuity" is required and how the "dead zone" is defined and maintained.

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: The specification describes the process as a significant departure from "layer-by-layer" fabrication, which could support an argument that any process that avoids discrete separation steps is "continuous," even if the movement is not perfectly uniform '601 Patent, col. 1:21-26
  • Evidence for a Narrower Interpretation: The abstract and detailed description emphasize that the dead zone is "maintained" and the carrier "advanc[es]... continuously," and Figure 1 depicts a smooth, uninterrupted gradient of polymerization. This may support an interpretation requiring constant, uninterrupted movement and a stable dead zone, potentially excluding processes that involve pauses or reciprocation '601 Patent, abstract '601 Patent, col. 2:21-33

• The Term: "a reactive blocked prepolymer" (from '142 Patent, Claim 1)

• Context and Importance: This term defines a key ingredient in the dual-cure resin. Infringement will depend entirely on whether LuxCreo's resins contain a chemical compound that meets this definition, which is further limited by specific chemical formulas in the claim.

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: The specification lists numerous examples of potential chemical groups that can be used for the "hydrocarbyl group" (X), the linking group (R), and the "blocking group" (Z), which could support a broader range of chemical structures falling under the claim '142 Patent, col. 33:1-46
  • Evidence for a Narrower Interpretation: The patent provides specific examples of synthesis for particular prepolymers. A defendant might argue that the term should be limited to the types of chemical structures and reactions actually demonstrated and enabled in the patent's working examples, particularly if the broader genus is not fully described '142 Patent, col. 36:36-67

VI. Other Allegations

• Indirect Infringement: The complaint notes that Carbon has accused LuxCreo of indirect infringement, presumably on the theory that LuxCreo provides its customers with the printers, resins, and instructions to carry out the allegedly infringing methods Compl. ¶ 18
• Willful Infringement: Carbon explicitly accused LuxCreo of "willful infringement" in its demand letters, establishing pre-suit knowledge Compl. ¶ 22 LuxCreo's filing of this DJ action is, in part, a response to this charge.
• Inequitable Conduct: The complaint makes extensive and detailed allegations of inequitable conduct against Carbon for several of the asserted "Dual Cure" patents (e.g., '963, '880, '868, '342, '895 patents) Compl. ¶¶248, 483, 611, 755, 991 LuxCreo alleges that the inventors, who are also founders and executives at Carbon, and their prosecuting attorneys intentionally withheld material prior art from the USPTO. The primary withheld references are identified as U.S. Patent No. 8,158,728 (the "'728 Patent") and U.S. Patent Pub. No. 2007/0178133 ("Rolland '133"), on which Carbon's own founders are named as inventors (Compl. ¶¶246; Compl. ¶ 249). The complaint argues that this prior art was not cumulative and was but-for material to the patentability of the claims, and that it was withheld with a specific intent to deceive the PTO (Compl. ¶¶373; Compl. ¶ 429).

VII. Analyst's Conclusion: Key Questions for the Case

• Enforceability and Credibility: The primary battleground appears to be the extensive allegations of inequitable conduct. A central question for the court will be whether LuxCreo can prove, by clear and convincing evidence, that Carbon's inventors and attorneys intentionally withheld the '728 and '133 prior art references with an intent to deceive the USPTO. The outcome of this issue could render a significant portion of Carbon's patent portfolio unenforceable and may impact the overall credibility of the parties.
• Validity Overlap: A related key issue is one of invalidity: irrespective of intent, does the allegedly withheld prior art (which shares inventors and subject matter with the asserted patents) anticipate or render obvious the claims of Carbon's dual-cure patents? The complaint's detailed invalidity claim charts suggest this will be a central technical argument.
• Technical Infringement: If the patents are found valid and enforceable, the case will turn on technical scope and function. For the CLIP patents, the question is whether LuxCreo's printing process truly practices the claimed "continuous" method with a "dead zone." For the dual-cure resin patents, the dispute will be a chemical one: do LuxCreo's resin compositions fall within the specific molecular structures defined in Carbon's claims?