Slingshot Printing LLC v. HP Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Slingshot Printing LLC (Delaware)
  • Defendant: HP Inc. (Delaware)
  • Plaintiff’s Counsel: The Mort Law Firm, PLLC
• Case Identification: 6:19-cv-00364, W.D. Tex., 09/20/19
• 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 Austin, Texas, employs numerous individuals including software and hardware engineers, owns real estate, and conducts substantial business through sales and reseller partnerships within the district.
• Core Dispute: Plaintiff alleges that Defendant’s inkjet printers, printheads, and ink cartridges infringe nine U.S. patents related to various aspects of inkjet printing technology, including ink fixing, printhead alignment, ink consumption tracking, media handling, and printhead maintenance.
• Technical Context: The patents address discrete technical challenges in the mature field of inkjet printing, where improvements in print quality, speed, reliability, and cost-efficiency are critical for market competitiveness.
• Key Procedural History: The patents-in-suit originated with Lexmark International, Inc. In 2013, Lexmark's inkjet technology and assets, including the patents-in-suit, were acquired by Funai Electric Co., Ltd., which subsequently assigned all rights to Plaintiff Slingshot Printing LLC.

Case Timeline

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

U.S. Patent No. 6,361,162 - “Method and apparatus for fixing ink to a print receiving medium”

The Invention Explained

• Problem Addressed: The patent’s background section describes how unfixed ink on print media can lead to problems such as bleeding, cockling (waviness), and smearing, which limit printing speed. It notes that conventional high-temperature dryer devices used to fix ink can be costly, consume significant power, and present safety hazards (U.S. Patent No. 6,361,162, col. 1:31-2:44).
• The Patented Solution: The invention proposes a method using a “tepidity device,” or a low-power heater, to gently warm ink droplets on the print medium. This warming, to a temperature of up to approximately 16° Celsius above the ambient atmosphere, is intended to accelerate the evaporation of the ink carrier (e.g., water) and fix the ink to the page more quickly, without the power consumption and safety issues of high-heat dryers (’162 Patent, Abstract; col. 3:1-12).
• Technical Importance: This approach aimed to improve print quality and fixation time on plain paper using a lower-power, safer, and less obtrusive heating mechanism, thereby increasing printer throughput (’162 Patent, col. 2:45-53).

Key Claims at a Glance

• The complaint asserts independent claim 1 and dependent claim 5 (Compl. ¶ 69).
• The essential elements of independent claim 1 include:
  • providing a portion of a print receiving medium in a print zone;
  • providing droplets of ink onto selected locations of the portion of the print receiving medium within the print zone;
  • generally warming the droplets of ink provided on the portion of the print receiving medium within the print zone to a temperature of up to about 16° Celsius above the temperature of the atmosphere to which the print zone is at least partially exposed;
  • wherein the step of providing droplets of ink occurs before the step of generally warming the droplets of ink.

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U.S. Patent No. 6,485,124 - “Optical alignment method and detector”

The Invention Explained

• Problem Addressed: The patent describes the importance of precise printhead alignment for print quality. It notes that prior art alignment detectors were often either inaccurate—by measuring reflected light over a large area—or costly, by requiring multiple lenses to achieve accurate "point detection" of small alignment marks on the media (U.S. Patent No. 6,485,124, col. 1:23-2:59).
• The Patented Solution: The invention discloses an optical alignment detector that uses only a "single focusing element" to image a point on the print media to a corresponding point on a photodetector. This design is intended to provide the accuracy of point detection while minimizing the number of optical components, thereby reducing manufacturing costs (’124 Patent, Abstract; col. 4:44-54).
• Technical Importance: The invention offered a method to achieve precise, low-cost printhead alignment, a critical factor for maintaining high print quality in mass-market inkjet printers (’124 Patent, col. 2:41-48).

Key Claims at a Glance

• The complaint asserts independent claim 1 and dependent claims 5-7 (Compl. ¶ 87).
• The essential elements of independent claim 1 include:
  • a light source;
  • an alignment sensor, wherein said alignment sensor includes a detector and a single focusing element to image a point on a media to a point on the detector; and
  • a control unit to determine whether said printing apparatus is aligned based on a detection by the alignment sensor of a predetermined mark on the media.

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U.S. Patent No. 6,601,934 - “Storage of total ink drop fired count in an imaging device”

• Technology Synopsis: The patent addresses the need to track ink usage over the life of a printer, rather than just for a single cartridge. It discloses a method of using two variables in memory: a first "COUNT" variable that increments with each drop fired, and a second "TOTAL INK CONSUMED" variable that increments only when the "COUNT" variable reaches a predetermined number, allowing for efficient storage of very large drop counts (U.S. Patent No. 6,601,934, Abstract).
• Asserted Claims: Claims 1, 8, 16, and 17 (Compl. ¶ 106).
• Accused Features: The complaint accuses the ink usage tracking functionality in HP printers, which provides a "Print Quality Diagnostic Report" listing "PHA Drops" as a total number of ink drops provided by a cartridge (Compl. ¶¶ 111-115).

U.S. Patent No. 6,666,449 - “Star wheel surface enhancement and process of manufacture”

• Technology Synopsis: The patent addresses the problem of ink and paper dust accumulating on the tips of "star wheels" (which guide paper out of the printer), leading to smearing on subsequent pages. The proposed solution is a manufacturing process that includes electropolishing the tips of the metallic star wheels to create an exceptionally smooth surface that resists ink adhesion (U.S. Patent No. 6,666,449, Abstract).
• Asserted Claims: Claims 1, 5, and 8 (Compl. ¶ 126).
• Accused Features: The complaint accuses the star wheels in certain HP inkjet printers, alleging they have a metallic body with radially extending projections and an electropolished surface on the tips (Compl. ¶¶ 130-131).

U.S. Patent No. 6,773,088 - “Double lipped printhead maintenance cap”

• Technology Synopsis: The patent addresses the challenge of creating an effective seal around a printhead to prevent ink nozzles from drying out. The invention is a maintenance cap featuring two distinct perimetrical sealing lips—a more compliant primary outer lip and a secondary inner lip—which together create a more reliable seal, especially on printheads with irregular surface topography (U.S. Patent No. 6,773,088, Abstract).
• Asserted Claims: Claims 8, 9, 20, and 22 (Compl. ¶ 141).
• Accused Features: The complaint accuses the printhead maintenance caps in HP printers, which are alleged to have a wall portion with a first and a second perimetrical lip defining primary and secondary sealing surfaces (Compl. ¶¶ 147-148).

U.S. Patent No. 7,222,936 - “Printhead carrier positioning apparatus and method”

• Technology Synopsis: The patent describes a method for managing the position of the printhead carrier for user convenience. When a user opens the printer cover, the carrier automatically moves to a cartridge exchange opening. If the cover is left open for a predetermined amount of time, the carrier returns to its home (capped) position to prevent nozzle drying. The user can then press a button to move it back to the exchange opening (U.S. Patent No. 7,222,936, Abstract).
• Asserted Claims: Claims 8-10 (Compl. ¶ 163).
• Accused Features: The complaint accuses the software-controlled carrier positioning logic in HP printers that moves the carrier to and from the cartridge exchange opening based on the cover status and elapsed time (Compl. ¶¶ 167-169).

U.S. Patent No. 7,819,498 - “Methods and systems using printhead tank memory to determine printhead tank configuration”

• Technology Synopsis: The patent addresses printers that support multiple ink tank configurations (e.g., a four-tank system vs. a two-tank system). The invention proposes storing "ink tank configuration instructions" on a memory tag on the ink tank itself. This allows the printer to read the tag and determine the specific configuration installed, avoiding unnecessary memory access operations for tank slots that are not in use (U.S. Patent No. 7,819,498, Abstract).
• Asserted Claims: Claims 1 and 2 (Compl. ¶ 181).
• Accused Features: The complaint accuses the memory tags (chips) on HP ink cartridges, which allegedly store data that provides the printer with an "ink tank identifier," allowing the printer to recognize correct vs. incorrect cartridge types (Compl. ¶¶ 188-191).

U.S. Patent No. 7,841,712 - “Automatic printhead and tank install positioning”

• Technology Synopsis: This patent relates to printers with semi-permanent printheads and on-carrier ink tanks, which may have different installation positions. The invention is a method where the printer uses sensors to determine the status of the ink tank (e.g., present, empty) and printhead, and then automatically moves the carrier to the correct position for the required task (e.g., ink tank replacement vs. printhead replacement) (U.S. Patent No. 7,841,712, Abstract).
• Asserted Claims: Claims 9, 10, and 14 (Compl. ¶ 207).
• Accused Features: The complaint accuses the functionality in HP T Series printers where the carrier moves to different positions for printhead and ink tank installation based on the status determined by sensors (Compl. ¶¶ 212, 215).

U.S. Patent No. 8,113,618 - “Methods and systems using printhead tank memory to determine printhead tank configuration”

• Technology Synopsis: As a continuation of the ’498 patent, this patent covers similar subject matter. It describes using a memory tag on an ink tank that contains configuration instructions, enabling a printer to identify the installed tank configuration and perform memory operations accordingly (U.S. Patent No. 8,113,618, Abstract).
• Asserted Claims: Claim 1 (Compl. ¶ 227).
• Accused Features: The complaint accuses the memory tags (chips) on HP ink cartridges, which are alleged to store "ink tank configuration instructions" that provide the printer with an ink tank identifier (Compl. ¶¶ 234-237).

III. The Accused Instrumentality

Product Identification

• The complaint accuses a wide range of HP inkjet products, including printers, printhead carriers, and ink cartridges across numerous product families such as the HP Designjet, OfficeJet, PageWide, Photosmart, Deskjet, and ENVY series (Compl. ¶¶ 69, 87, 106, 126, 141, 163, 181, 207, 227). The infringement allegations use specific products as exemplars, including the HP Designjet 10000s Printer series for the '162 patent and the HP OfficeJet Pro 7740 for the '124 patent (Compl. ¶¶ 71, 89).

Functionality and Market Context

• The accused products are inkjet printing devices and consumables sold for consumer and commercial use. HP is a prominent manufacturer in the global printer market. The accused functionalities relate to core operations of these devices. For example, the complaint alleges the HP 10000s printer uses a three-heater system for fixing and stabilizing the printed image (Compl. ¶ 72). A diagram from the product's user guide illustrates the media path relative to the front, print, and rear heaters (Compl. ¶ 72, p. 17). For the HP OfficeJet Pro 7740, the complaint identifies an LED light source and an alignment sensor on the printhead carriage, which are used to detect marks on the media for alignment purposes (Compl. ¶¶ 91-94). An annotated photograph in the complaint purports to show the "LED light" on the carriage assembly (Compl. ¶ 91, p. 23).

IV. Analysis of Infringement Allegations

U.S. Patent No. 6,361,162 Infringement Allegations

• Identified Points of Contention:
  • Technical Questions: A primary factual question will be whether the accused HP printers' heating systems operate within the specific thermal parameters of claim 1. The complaint alleges, "on information and belief," that the warming is "up to about 16° Celsius above the temperature of the atmosphere" (Compl. ¶ 77). This allegation directly tracks the claim language and will require evidentiary support, likely through expert testing and analysis, to demonstrate that the accused devices actually function in this manner.
  • Scope Questions: The construction of the term "generally warming" may become a point of contention, raising questions about the uniformity and duration of the heating required to meet this limitation.

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U.S. Patent No. 6,485,124 Infringement Allegations

• Identified Points of Contention:
  • Scope Questions: The central dispute may concern the claim term "a single focusing element." The patent's background distinguishes the invention from prior art using multiple lenses ('124 Patent, col. 2:50-52). The question for the court will be whether the optical component in the accused HP sensor, which the complaint labels a "Single Focusing Element" (Compl. ¶ 93, p. 24), meets the legal definition of this term. A defendant may argue that the accused component is a compound lens or comprises multiple optical pieces, and therefore does not satisfy the "single" element limitation.

V. Key Claim Terms for Construction

• For U.S. Patent No. 6,361,162:

  • The Term: "generally warming the droplets of ink . . . to a temperature of up to about 16° Celsius above the temperature of the atmosphere"
  • Context and Importance: This limitation defines the core of the invention—a low-temperature ink-fixing method. Infringement will depend on whether the accused printers' heaters operate within this specific, relatively modest temperature range, distinguishing it from conventional high-heat dryers.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The use of "generally" and "about" may support a construction that does not require rigid adherence to the 16°C upper limit. The specification describes the invention as a "tepidity device," suggesting the emphasis is on moderate, rather than high, heat (’162 Patent, col. 2:58-60).
    • Evidence for a Narrower Interpretation: The specification repeatedly recites the "about 16° Celsius" value in the abstract, summary, and detailed description, suggesting its significance. Figure 5 of the patent presents a graph showing that the peak improvement in "Gamut Volume" occurs at a delta temperature of 16°C, which a party could argue underscores the centrality of this specific value to the claimed invention (’162 Patent, Fig. 5).

• For U.S. Patent No. 6,485,124:

  • The Term: "a single focusing element"
  • Context and Importance: This term is the primary point of novelty asserted over prior art alignment sensors that allegedly required multiple lenses for accurate point detection. The case may turn on whether the accused device's optical assembly constitutes one "element" or multiple.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification states the element performs "one focusing operation" (col. 5:48-51). Plaintiff may argue this means any integrated optical component that performs a single net focusing function qualifies, regardless of its internal construction.
    • Evidence for a Narrower Interpretation: The background explicitly contrasts the invention with a prior art system using two lenses ("lenses 120 and 110") ('124 Patent, col. 2:50-52). A defendant could argue that "a single focusing element" must therefore be a single, monolithic optical component, not a compound lens assembly made of multiple pieces cemented together or housed as one unit.

VI. Other Allegations

• Indirect Infringement: The complaint alleges inducement of infringement for all asserted patents. The allegations are based on HP knowingly encouraging and instructing customers and resellers to use the accused products in an infringing manner through user guides, manuals, advertisements, and other promotional materials (e.g., Compl. ¶¶ 79-81, 98-100).
• Willful Infringement: The complaint does not explicitly use the term "willful infringement." It pleads that HP has had knowledge of the patents "at least as early as the filing and service of this First Amended Complaint," which may form the basis for alleging post-suit indirect infringement or enhanced damages for post-suit conduct, but does not allege pre-suit knowledge (e.g., Compl. ¶ 78).

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

This case presents a broad challenge to HP's inkjet printer portfolio, turning on a combination of technical evidence and legal interpretation of claim scope. The central questions for the court will likely be:

1. A core issue will be one of factual correspondence: For patents concerning physical properties and operational parameters, such as the '162 patent’s specific heating range and the ’449 patent’s electropolished star wheels, a key question will be evidentiary. Can Plaintiff produce technical evidence from testing and analysis to prove that the accused HP products, as sold and operated, actually meet these specific, quantitative claim limitations alleged "on information and belief"?

2. A second key issue will be one of definitional scope: For patents concerning structural components, such as the '124 patent’s "single focusing element" and the '498 patent’s "ink tank configuration instructions," the dispute may center on claim construction. Can the terms, as defined in the context of the patent specifications, be construed to cover the corresponding components in HP's printers, or will HP be able to demonstrate a fundamental structural or functional mismatch that places its technology outside the scope of the claims?