DCT

1:20-cv-00185

Slingshot Printing LLC v. HP Inc

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 6:19-cv-00363, W.D. Tex., 09/20/2019
  • Venue Allegations: Plaintiff alleges venue is proper in the Western District of Texas because Defendant HP Inc maintains a regular and established place of business in the district, including a corporate office and data centers in Austin, employs Texas residents, owns real estate, and conducts substantial business through a network of partners and resellers.
  • Core Dispute: Plaintiff alleges that Defendant’s inkjet printers and ink cartridges infringe eight patents related to the design and operation of inkjet printheads, including technologies for varying droplet size, shaping bubble chambers, and arranging components on the heater chip.
  • Technical Context: The patents address micro-fabrication and fluid dynamic challenges in thermal inkjet printheads, an established technology central to the consumer and commercial printing markets.
  • Key Procedural History: The complaint states that the patents-in-suit originated with Lexmark International, Inc. and were acquired by Funai Electric Co., Ltd. in 2013 before being assigned to the Plaintiff, Slingshot Printing LLC.

Case Timeline

Date Event
1999-08-27 U.S. Patent No. 6,137,502 Priority Date
2000-10-24 U.S. Patent No. 6,137,502 Issued
2002-12-30 U.S. Patent Nos. 6,863,381; 7,014,299; 7,077,509; 7,244,015 Priority Date
2003-03-25 U.S. Patent No. 6,719,405 Priority Date
2004-02-10 U.S. Patent No. 7,152,951 Priority Date
2004-04-13 U.S. Patent No. 6,719,405 Issued
2005-03-08 U.S. Patent No. 6,863,381 Issued
2005-09-30 U.S. Patent No. 7,364,268 Priority Date
2006-03-21 U.S. Patent No. 7,014,299 Issued
2006-07-18 U.S. Patent No. 7,077,509 Issued
2006-12-26 U.S. Patent No. 7,152,951 Issued
2007-07-17 U.S. Patent No. 7,244,015 Issued
2008-04-29 U.S. Patent No. 7,364,268 Issued
2019-09-20 Complaint Filing Date

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

U.S. Patent No. 6,137,502 - “Dual droplet size printhead”

The Invention Explained

  • Problem Addressed: The patent describes the challenge of creating inkjet printers capable of ejecting multiple droplet sizes to improve gray-scale image quality. A key problem is that simply using different-sized nozzles and heaters can cause undesirable variations in the energy delivered to the ink, which degrades print quality (’502 Patent, col. 2:36-41).
  • The Patented Solution: The invention proposes a printhead with two sets of nozzles: larger "first nozzles" for ejecting larger ink drops and smaller "second nozzles" for smaller drops. To improve efficiency, the heaters associated with the large nozzles have a larger surface area than those for the small nozzles (’502 Patent, col. 2:45-51). Crucially, to ensure consistent energy delivery across all nozzles, the invention specifies that the voltage drop across the switching devices for the first heaters is "substantially equivalent" to the voltage drop across the switching devices for the second heaters (’502 Patent, Abstract; col. 2:15-20).
  • Technical Importance: This approach aimed to enable higher-quality, photo-realistic printing by providing more gray-scale levels, while simultaneously addressing the engineering challenge of maintaining consistent and efficient energy delivery in a complex micro-electro-mechanical system (’502 Patent, col. 1:13-20).

Key Claims at a Glance

  • The complaint asserts independent claim 19 (’502 Patent, Compl. ¶65).
  • Essential elements of claim 19 include:
    • A nozzle plate with first nozzles of a first diameter and second nozzles of a second, smaller diameter.
    • A substrate adjacent to the nozzle plate.
    • First heater-switch pairs, comprising first heaters (with a first heater area) and first switching devices, which develop a first switching device voltage drop.
    • Second heater-switch pairs, comprising second heaters (with a second, smaller heater area) and second switching devices, which develop a second switching device voltage drop.
    • The first and second heater-switch pairs are connected in parallel.
    • The first heater area is larger than the second heater area.
    • The first switching device voltage drop is substantially equivalent to the second switching device voltage drop.

U.S. Patent No. 6,719,405 - “Inkjet printhead having convex wall bubble chamber”

The Invention Explained

  • Problem Addressed: The patent notes that when both the heater element and its surrounding bubble chamber are rectangular, stagnant regions can form that trap air bubbles. Over time, these bubbles can grow and prevent proper heat transfer, leading to heater failure and poor print performance (’405 Patent, col. 1:42-51).
  • The Patented Solution: The invention proposes a bubble chamber with a "curved or convex wall portion" that partially surrounds a "substantially rectangular" heater element. This curved geometry is designed to eliminate stagnant corners and prevent the accumulation of air bubbles (’405 Patent, Abstract; col. 2:25-30). The patent describes specific geometric relationships, such as the radius of the curved portion being greater than half the heater's width but less than half its length, ensuring that the chamber wall does not overlie the heater's periphery (’405 Patent, col. 2:1-5).
  • Technical Importance: This design addresses a key reliability issue in thermal inkjet technology by improving the fluid dynamics within the microscopic bubble chamber to prevent failures caused by trapped air (’405 Patent, col. 1:52-54).

Key Claims at a Glance

  • The complaint asserts claims 1-4, 7, 8, and 16-20, which include independent claims 1, 7, and 17 (’405 Patent, Compl. ¶92).
  • Essential elements of independent claim 1 include:
    • A substantially rectangular heater element with a length and width dimension where the aspect ratio is greater than about 2.0.
    • A bubble chamber with a convex wall portion partially surrounding the heater element.
    • The convex wall portion has an arc with a radius that is greater than about 0.5 of the width dimension and less than about 0.5 of the length dimension.
    • None of the convex wall portion overlies the periphery of the heater element.
    • A nozzle plate with an orifice, where the ink ejection side of the orifice is directly above the heater element.

U.S. Patent No. 6,863,381 - “Inkjet printhead heater chip with asymmetric ink vias”

  • Technology Synopsis: The patent addresses the design of the heater chip, which contains the fluid firing elements and ink vias (channels for ink supply). The invention describes a heater chip where the ink via is arranged asymmetrically, with the column of fluid firing elements existing exclusively along only one side of the via, a design intended to save silicon die space and reduce manufacturing costs (’381 Patent, Abstract; col. 1:6-10).
  • Asserted Claims: Claims 1 and 3-5 are asserted; claim 1 is independent (Compl. ¶117).
  • Accused Features: The complaint alleges that the heater chip of the HP 63 tricolor cartridge infringes by having a chip centroid and an ink via centroid that do not coexist, with the fluid firing elements existing exclusively on one side of the via (Compl. ¶¶123-126). The complaint provides a micrograph of the HP 63 heater chip, identifying the alleged chip centroid (Compl. ¶123).

U.S. Patent No. 7,014,299 - “Inkjet printhead heater chip with asymmetric ink vias”

  • Technology Synopsis: This patent, related to the ’381 patent, further describes an inkjet printhead heater chip with an asymmetric ink via arrangement. The claims focus on the location of the chip's centroid relative to the ink vias and the columns of fluid firing elements, another configuration aimed at optimizing the use of silicon real estate (’299 Patent, Abstract).
  • Asserted Claims: Claims 1-3 are asserted; claim 1 is independent (Compl. ¶141).
  • Accused Features: The complaint accuses the HP 64 tricolor printhead, alleging its heater chip has a chip centroid located between the boundary of a middle ink via and a middle column of fluid firing elements (Compl. ¶¶147-148).

U.S. Patent No. 7,077,509 - “Inkjet printhead heater chip with asymmetric ink vias”

  • Technology Synopsis: Also related to the ’381 patent, this patent describes a heater chip architecture where columns of fluid firing elements and columns of input terminals (e.g., transistors) are arranged in parallel, with the firing elements existing exclusively along one side of an ink via (’509 Patent, Abstract). This layout concerns the electrical and physical arrangement for efficient operation and manufacturing.
  • Asserted Claims: Claim 11 is asserted and is independent (Compl. ¶159).
  • Accused Features: The complaint accuses the heater chip of the HP 63 tricolor cartridge, alleging it has parallel columns of fluid firing elements and input terminals, with the firing elements located exclusively along one side of the ink vias (Compl. ¶¶167-169).

U.S. Patent No. 7,152,951 - “High resolution ink jet printhead”

  • Technology Synopsis: This patent describes a high-resolution printhead architecture for achieving a high dot-per-inch (dpi) pitch. It involves a semiconductor substrate with an ink feed edge and a plurality of ink ejection actuators (heaters) spaced at a substantially uniform distance from that edge, combined with a thick film layer containing ink feed chambers and channels (’951 Patent, Abstract).
  • Asserted Claims: Claims 1 and 2 are asserted; claim 1 is independent (Compl. ¶179).
  • Accused Features: The complaint accuses the printhead in the HP OfficeJet Pro 6978, alleging it has a semiconductor substrate with an ink feed edge, heater resistors with a specific aspect ratio, and attached thick film and nozzle plate layers (Compl. ¶¶183-187).

U.S. Patent No. 7,244,015 - “Inkjet printhead heater chip with asymmetric ink vias”

  • Technology Synopsis: This patent, from the same family as the ’381 patent, focuses on a rectangular heater chip with multiple parallel ink vias that are disposed closer to one of the two short ends of the chip. This asymmetric placement of the entire via structure is another method intended to optimize silicon usage (’015 Patent, Abstract).
  • Asserted Claims: Claim 1 is asserted and is independent (Compl. ¶197).
  • Accused Features: The complaint accuses the HP 6978 Printhead, alleging it has a rectangular heater chip with at least three parallel ink vias positioned closer to one of the two short ends (Compl. ¶¶201-203).

U.S. Patent No. 7,364,268 - “Nozzle members, compositions and methods for micro-fluid ejection heads”

  • Technology Synopsis: This patent describes an improved photoimaged nozzle member for a printhead. The key feature is a nozzle with a "reentrant profile," meaning the exit diameter is smaller than the entrance diameter, with a specific wall angle (greater than 4°). This nozzle shape is intended to reduce the energy required to eject fluid droplets (’268 Patent, Abstract).
  • Asserted Claims: Claims 1, 2, 8, and 9 are asserted; claims 1 and 8 are independent (Compl. ¶213).
  • Accused Features: The complaint accuses the nozzle members of the HP OfficeJet Pro 6978 and HP Page Wide Pro MFP 477dw. It alleges these products have a photoresist nozzle layer with nozzles having a reentrant profile and a wall angle within the claimed range (e.g., about 7.7° for the 6978 and 16° for the 477dw) (Compl. ¶¶217-219, 222-224).

III. The Accused Instrumentality

Product Identification

  • The complaint accuses a wide range of HP products, categorized as Inkjet Printers and Ink Cartridges/Printheads (Compl. ¶¶65, 92, 117, 141, 159, 179, 197, 213). Specific examples used to demonstrate infringement include HP 62, 63, 64, and 88 series ink cartridges, as well as the HP OfficeJet Pro 6978 and HP Page Wide Pro MFP 477dw printers and their associated printheads (Compl. ¶¶69, 94, 121, 181, 215).

Functionality and Market Context

  • The accused products are thermal inkjet printers and the consumable ink cartridges that contain the printhead technology. The complaint alleges these products function by ejecting ink droplets from microscopic nozzles that are activated by heating elements fabricated on a semiconductor chip (Compl. ¶¶30-31). The complaint asserts that HP sells these products throughout the United States via major retailers, its own website, and a formal "Partners First Program" with resellers in the judicial district (Compl. ¶¶14-17, 21-22). The complaint provides a screenshot from HP's website showing numerous authorized resellers in Austin, Texas (Compl. ¶16).

IV. Analysis of Infringement Allegations

U.S. Patent No. 6,137,502 Infringement Allegations

Claim Element (from Independent Claim 19) Alleged Infringing Functionality Complaint Citation Patent Citation
a nozzle plate containing the plurality of nozzles; the plurality of nozzles including first nozzles having a first diameter for ejecting droplets of ink having a first mass, and second nozzles having a second diameter for ejecting droplets of ink having a second mass...the first diameter is larger than the second diameter... The HP 64 printhead has a nozzle plate with first nozzles (approx. 15.7 µm diameter) and second nozzles (approx. 12.2 µm diameter). ¶¶71-72 col. 2:51-57
first heater-switch pairs comprising: first heaters disposed on the substrate adjacent the first nozzles...occupying a first heater area... The HP 64 printhead has first heaters made of electrically resistive material disposed on the substrate adjacent to the first nozzles, occupying a first heater area. ¶75 col. 2:55-60
second heater-switch pairs comprising: second heaters disposed on the substrate adjacent the second nozzles...occupying a second heater area... The HP 64 printhead has second heaters made of electrically resistive material disposed on the substrate adjacent to the second nozzles, occupying a second heater area. ¶78 col. 2:67-3:5
wherein...the first heater area is larger than the second heater area... The first heater area of the HP 64 printhead is alleged to be larger than the second heater area. A micrograph with measurements is provided as support. ¶81 col. 1:1-4
and first switching devices...each of the first switching devices developing a first switching device voltage drop...and second switching devices...each of the second switching devices developing a second switching device voltage drop... The HP 64 printhead has first switching devices in series with the first heaters, and second switching devices in series with the second heaters, which develop respective voltage drops. ¶¶76, 79 col. 2:60-63, 3:5-8
wherein...the first switching device voltage drop is substantially equivalent to the second switching device voltage drop. The complaint alleges on information and belief that the first switching device voltage drop is substantially equivalent to the second switching device voltage drop. ¶82 col. 2:15-20

U.S. Patent No. 6,719,405 Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
a substantially rectangular heater element having a periphery with a length and width dimension such that an aspect ratio of said length dimension to said width dimension is greater than about 2.0; The HP 88 printhead has a plurality of substantially rectangular heater elements for cyan and magenta ink with alleged aspect ratios of about 2.6 and 2.8, respectively, both greater than 2.0. ¶¶97-98 col. 2:25-28
a bubble chamber having a convex wall portion partially surrounding said heater element... The HP 88 printhead has a plurality of bubble chambers that have a convex wall portion partially surrounding the heater element. A micrograph shows this structure. ¶99 col. 2:28-30
said convex wall portion having an arc with a radius that is greater than about 0.5 said width dimension and less than about 0.5 said length dimension... For both cyan and magenta ink, the convex wall portion is alleged to have an arc with a radius that meets the claimed dimensional constraints relative to the heater's width and length. ¶¶100-101 col. 2:30-33
and none of said convex wall portion overlies said periphery of said heater element... The complaint alleges that none of the convex wall portion overlies the periphery of the heater element, providing a micrograph as an example. ¶102 col. 2:33-35
a nozzle plate having a thickness with an orifice therein, an ink ejection side of said orifice being directly above said heater element. The HP 88 has a nozzle plate with an orifice, and the ink ejection side of the orifice is alleged to be directly above the heater element. ¶103 col. 2:6-9

Identified Points of Contention

  • Scope Questions: Across multiple patents (’381, ’299, ’509, ’015), a central question will be whether the term "asymmetric," as defined by the claims' specific geometric limitations (e.g., non-coincident centroids, placement relative to chip edges), reads on the accused HP heater chip layouts. The infringement analysis for the ’268 patent will raise the question of whether the accused nozzles' measured wall angles fall within the claimed range of "greater than about 4° up to about 30°."
  • Technical Questions: For the ’502 patent, a key factual question will be what evidence supports the allegation that the switching device voltage drops are "substantially equivalent." The complaint makes this allegation "on information and belief," which suggests it may be an area of significant discovery and expert dispute. For the ’405 patent, the court will have to determine if the accused heater elements are "substantially rectangular" and if the accused bubble chambers have a "convex wall portion" that meets the specific dimensional ratios required by the claim.

V. Key Claim Terms for Construction

  • The Term: "substantially equivalent" (’502 Patent, claim 19)

  • Context and Importance: This term defines the electrical relationship between the switching devices for the large and small nozzle heaters. Its construction is critical because the patent presents this equivalence as the key to solving the problem of uneven energy delivery. Practitioners may focus on this term because its inherent flexibility (as a term of degree) creates a focal point for non-infringement arguments.

  • Intrinsic Evidence for Interpretation:

    • Evidence for a Broader Interpretation: The specification states the goal is to "reduce undesirable nozzle-to-nozzle variations in the amount of energy delivered to the ink" and "significantly enhance print quality" (’502 Patent, col. 2:15-24). This functional language could support an interpretation where any degree of equivalence that achieves this stated goal meets the limitation.
    • Evidence for a Narrower Interpretation: The detailed description sets up a specific mathematical relationship for the resistances of the switching devices (Rs1/Rs2 ≃ RH1/RH2) to achieve the desired outcome (’502 Patent, col. 6:39-42). A defendant may argue this specific formula narrows the scope of "substantially equivalent" to only those designs that satisfy this or a very similar electrical ratio.

  • The Term: "convex wall portion" (’405 Patent, claim 1)

  • Context and Importance: This term describes the novel shape of the bubble chamber designed to prevent bubble trapping. The precise geometric meaning of "convex" in this context is central to infringement, as it distinguishes the invention from prior art rectangular chambers.

  • Intrinsic Evidence for Interpretation:

    • Evidence for a Broader Interpretation: The specification suggests this term is not limited to a perfectly smooth curve, stating it "may consist of generally rounded or curved walls or as a series of substantially straight walls approximating a curve" (’405 Patent, col. 4:1-5). This explicit language provides strong support for a broader construction that includes faceted or approximated curves.
    • Evidence for a Narrower Interpretation: The primary embodiment shown in Figure 1a depicts a distinct, smooth, nearly circular curve (’405 Patent, Fig. 1a). A defendant might argue that this preferred embodiment limits the term to smoothly curved structures, rather than those composed of straight-line segments.

VI. Other Allegations

  • Indirect Infringement: For all eight patents, the complaint alleges induced infringement under 35 U.S.C. § 271(b). The allegations state that HP knowingly encourages infringement by providing customers and resellers with user guides, manuals, advertisements, and website support that instruct on the setup and use of the accused inkjet printers and cartridges (e.g., Compl. ¶¶84, 86, 109, 111, 133, 135).
  • Willful Infringement: The complaint does not contain an explicit count for willful infringement. However, for each asserted patent, it alleges that HP has had knowledge of the patent "at least as early as the filing and service of the Complaint" or "this First Amended Complaint" and has continued its allegedly infringing conduct thereafter (e.g., Compl. ¶¶83, 108, 132). These allegations of post-filing knowledge could form the basis for a later claim of willful infringement and enhanced damages.

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

  • A core issue will be one of definitional scope and measurement: do the accused micro-structures, as measured and characterized by experts, fall within the specific quantitative and qualitative limitations of the claims? This will apply to terms such as the "substantially equivalent" voltage drops of the ’502 patent, the precise geometric ratios of the ’405 patent’s bubble chamber, and the "reentrant profile" wall angles of the ’268 patent.
  • A second central question will concern claim construction of structural arrangements: can the various patents covering "asymmetric" layouts of ink vias and firing elements on heater chips (’381, ’299, ’509, ’015) be construed to cover the specific chip architectures used by HP? The case will likely feature competing analyses of micrographs to determine if the accused products meet the claimed spatial relationships, such as the non-coincident placement of chip and via centroids.
  • A key evidentiary question will be one of intent for indirect infringement: what evidence beyond the provision of standard product documentation can Plaintiff show to prove HP possessed the specific intent required to induce its customers and resellers to infringe the asserted patents?