DCT
1:20-cv-00189
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; Goldberg Segalla LLP
- Case Identification: 6:20-cv-00048, W.D. Tex., 01/23/2020
- Venue Allegations: Plaintiff alleges venue is proper in the Western District of Texas because HP maintains a regular and established place of business in the district, including corporate offices and data centers in Austin, and employs numerous residents there.
- Core Dispute: Plaintiff alleges that Defendant’s inkjet printers and their internal heater chips infringe two patents related to methods for sensing and regulating temperature within an inkjet printhead.
- Technical Context: The technology concerns the thermal management of micro-fabricated heater chips in inkjet printheads, where precise temperature control is critical for consistent ink droplet size and overall print quality.
- Key Procedural History: The patents-in-suit originated with Lexmark International, Inc. and were acquired by Funai Electric Co., Ltd. before being assigned to Plaintiff. The complaint alleges that Defendant had pre-suit knowledge of the ’823 patent from a prior litigation (Case No. 6:19-cv-00549) and of the ’708 patent from a specific date, which may support the willfulness allegations.
Case Timeline
| Date | Event |
|---|---|
| 2005-12-30 | Earliest Priority Date for ’823 and ’708 Patents |
| 2009-02-03 | U.S. Patent No. 7,484,823 Issued |
| 2009-09-29 | U.S. Patent No. 7,594,708 Issued |
| 2019-09-27 | Alleged Notice of ’823 Patent via filing of Case 6:19-cv-00549 |
| 2019-12-11 | Alleged Notice of ’708 Patent |
| 2020-01-23 | Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 7,484,823 - “Methods and apparatuses for regulating the temperature of multi-via heater chips” (Issued Feb. 3, 2009)
The Invention Explained
- Problem Addressed: The patent’s background section describes a challenge in high-resolution inkjet printheads that place heater arrays on both sides of an ink via. In such designs, traditional temperature sensing methods are inadequate. A single sensor for the entire chip provides only an average temperature, while placing sensors next to each heater array can lead to inaccurate readings due to thermal crosstalk between adjacent color regions, negatively impacting print quality (ʼ823 Patent, col. 1:48-2:50).
- The Patented Solution: The invention proposes a specific arrangement for thermal control. It teaches positioning a temperature sensing element within the silicon "region" that lies between two adjacent heater arrays. By placing the sensor centrally in this region, it can obtain a more accurate temperature reading for that specific zone, isolated from the direct influence of a single heater ('823 Patent, Abstract). This temperature reading is then used to apply responsive heating—such as short, non-ejecting heat pulses—to the adjacent heater arrays to maintain an optimal operating temperature ('823 Patent, col. 2:56-3:3). Figure 5 of the patent illustrates this concept, showing temperature sense resistors (e.g., 542) placed in distinct regions (e.g., 432) between heater arrays.
- Technical Importance: This approach provided a method for more precise thermal management in high-density printheads using dual-sided heater arrays, which is a key factor in achieving consistent ink drop weight and color fidelity ('823 Patent, col. 1:48-55).
Key Claims at a Glance
- The complaint asserts independent claims 1 and 11, along with several dependent claims (Compl. ¶41).
- Independent Claim 1 (Apparatus):
- a first heater array positioned substantially adjacent a first via;
- a second heater array positioned substantially adjacent a second via;
- a region positioned between the first and second heater arrays;
- a temperature sensing element operable to sense the temperature of the region, where the element is "substantially centrally disposed" with respect to the region and extends substantially the length of the heater arrays; and
- the heater arrays are operable to receive heating responsive to the sensed temperature to regulate the temperature of the region.
- Independent Claim 11 (Method):
- providing first and second heater arrays adjacent to first and second vias, respectively;
- positioning a temperature sensing element in a region between the heater arrays; and
- responsive to the sensed temperature, heating the heater arrays to regulate the temperature of the region.
U.S. Patent No. 7,594,708 - “Methods and apparatuses for sensing temperature of multi-via heater chips” (Issued Sep. 29, 2009)
The Invention Explained
- Problem Addressed: The '708 patent addresses the same technical problem as its related '823 patent: the difficulty of achieving accurate, per-color temperature control in heater chips where heater arrays for different colors are in close proximity on the silicon substrate ('708 Patent, col. 1:48-2:50).
- The Patented Solution: The solution is similar but framed differently. The invention describes a chip with multiple parallel ink vias, each flanked by two heater arrays. The key inventive concept is the placement of a "single temperature sensing element" within each defined "region" between adjacent ink vias. This sensor is positioned at a "predetermined distance away from adjacent heater arrays" to accurately sense the temperature of that specific zone, which includes the two heater arrays associated with the adjacent vias ('708 Patent, Abstract; col. 6:40-50).
- Technical Importance: Like the ’823 patent, this invention provides a technique for discrete thermal monitoring and management in dense, multi-color inkjet printheads, enabling higher-resolution printing ('708 Patent, col. 1:40-47).
Key Claims at a Glance
- The complaint asserts independent claims 1 and 9, along with several dependent claims (Compl. ¶71).
- Independent Claim 1 (Apparatus):
- a plurality of parallel ink vias, each with two longitudinal sides;
- a heater array disposed adjacent each longitudinal side of the ink vias;
- a region disposed between two adjacent ink vias, which includes two heater arrays; and
- a "single temperature sensing element" disposed within each region, operable to sense the temperature and positioned at a "predetermined distance" from the heater arrays.
- Independent Claim 9 (Method):
- arranging parallel ink vias;
- placing a heater array adjacent each longitudinal side of the vias;
- defining a region between adjacent vias; and
- positioning a "single temperature sensing element" within each region at a "predetermined distance" away from the heater arrays.
III. The Accused Instrumentality
Product Identification
The complaint identifies "Inkjet printers including, without limitation, HP OfficeJet Pro 6978" and the "tricolor heater chip" contained within the printer's ink cartridges as the accused instrumentalities (Compl. ¶¶41, 44, 71, 74).
Functionality and Market Context
The complaint focuses on the technical layout of the tricolor heater chip. It provides a series of annotated micrographs purporting to show the chip's internal structure, including features labeled as ink vias, heater arrays, and temperature sensing elements (Compl. ¶¶45-55, 75-79). The complaint alleges HP has a significant market presence, selling the accused printers through retail stores and an extensive "Partners First Program" with resellers throughout the judicial district, including in Austin, Waco, and San Antonio (Compl. ¶¶14, 16, 22). The complaint includes a screenshot from HP's website showing its reseller search tool, which identifies numerous partners in the Austin area (Compl. ¶16, p. 7).
IV. Analysis of Infringement Allegations
’823 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a first heater array positioned substantially adjacent a first via; | The complaint alleges the HP 6978 tricolor heater chip has a first heater array positioned next to a first ink via. An annotated micrograph shows a structure labeled "First heater array" next to one labeled "First ink via." | ¶45 | col. 7:46-47 |
| a second heater array positioned substantially adjacent a second via; | The accused chip is alleged to have a second heater array positioned next to a second ink via. | ¶46 | col. 7:48-49 |
| a region, positioned between the first heater array and the second heater array... | The accused chip is alleged to contain a region positioned between the first and second heater arrays. A micrograph highlights a "Region" between the two identified heater arrays. | ¶47 | col. 7:50-53 |
| a temperature sensing element operable to sense a temperature of the region...wherein the temperature sensing element is substantially centrally disposed with respect to the region...and further extends substantially the length of the first heater array and second heater array, | The complaint alleges the accused chip has a temperature sensing element that is centrally disposed in the region, is adjacent to both heater arrays, and extends their length. An annotated micrograph shows a long, narrow structure labeled "Temperature sensing element" running between the two heater arrays. | ¶48 | col. 7:54-8:2 |
| wherein the first heater array and the second heater array are operable to receive heating responsive to the temperature of the region...and wherein the received heating regulates the temperature of the region. | The heater arrays are alleged to be operable to receive heating based on the sensed temperature to regulate the region's temperature, controlled by a "main controller board." | ¶¶49, 58 | col. 8:3-7 |
Identified Points of Contention
- Scope Questions: The infringement case may turn on the construction of relative terms like "substantially adjacent" and "substantially centrally disposed." The parties may dispute whether the physical arrangement shown in the complaint's micrographs (Compl. ¶48, p. 17), which depicts a long element between two arrays, meets the geometric and spatial requirements of the claim language.
- Technical Questions: A key question is whether the structure identified by the plaintiff as a "temperature sensing element" actually performs the claimed function of sensing temperature for the purpose of regulating heat in that specific region. The complaint provides visual evidence of the structure, but evidence of its specific operation will be necessary to prove infringement.
’708 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a plurality of ink vias arranged parallel to one another, each...having two longitudinal sides; | The accused chip is alleged to have multiple parallel ink vias. A micrograph displays three structures labeled "Ink via" arranged in parallel. | ¶75 | col. 7:31-33 |
| a heater array disposed adjacent each longitudinal side of the ink vias such that each ink via is associated with two heater arrays... | The accused chip allegedly has heater arrays along both sides of the ink vias. An annotated micrograph identifies structures labeled "Heater Arrays along ink vias." | ¶76 | col. 7:34-38 |
| a region disposed adjacent each heater array, wherein only one region is disposed between two adjacent ink vias and wherein the region...includes two heater arrays... | The accused chip is alleged to have a region between adjacent ink vias that contains two heater arrays. A micrograph points to "Regions" containing "Heater Arrays" between the ink vias. | ¶77 | col. 7:39-44 |
| a single temperature sensing element disposed within each region,...operable to sense a temperature...and disposed at a predetermined distance away from adjacent heater arrays. | The accused chip allegedly has a single temperature sensing element in each region, set at a predetermined distance from the heaters, to sense temperature. This allegation is supported by the same micrograph evidence as for the ’823 patent. | ¶78 | col. 7:45-50 |
Identified Points of Contention
- Scope Questions: The claim requires a "single temperature sensing element" per region. A potential point of dispute is whether the accused sensing architecture constitutes a "single" element as construed by the court, or if it functions as a distributed or multi-part sensor that falls outside the claim's scope.
- Technical Questions: The term "predetermined distance" may be a focus of claim construction. The complaint alleges the sensor is at least 300 microns away (Compl. ¶80), but the court will have to determine if this distance meets the "predetermined" requirement as understood in the context of the patent.
V. Key Claim Terms for Construction
’823 Patent: "substantially centrally disposed" (Claim 1)
- Context and Importance: This term is central to the patent's proposed solution. The invention's asserted benefit of improved accuracy depends on placing the sensor in a location that is not overly influenced by either adjacent heater array. Practitioners may focus on this term because the infringement analysis will hinge on whether the accused chip's sensor placement meets this specific geometric constraint.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The specification suggests some flexibility, noting that sensors "can be positioned at any point within their respective thermal regions" ('823 Patent, col. 7:8-10). This language could support an interpretation that does not require strict geometric centering.
- Evidence for a Narrower Interpretation: The claim language itself, as well as the abstract, explicitly uses "substantially centrally disposed." Furthermore, the patent's Figure 5, an exemplary embodiment, visually depicts the temperature sensors (e.g., 542, 544) as being located at or near the geometric midpoint of their respective regions, potentially supporting a narrower construction.
’708 Patent: "single temperature sensing element" (Claim 1)
- Context and Importance: This term is critical to defining the patented architecture, which contrasts with prior art that might use multiple sensors. The question of whether the accused device uses a "single" element per region is fundamental to infringement.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: A party could argue that "single... element" should be interpreted functionally, meaning any structure or group of components that produces one unitary temperature reading for the region could meet the limitation.
- Evidence for a Narrower Interpretation: The plain language "a single... element" and the depiction in Figure 5 of discrete, individual resistors (TSRs) for each region strongly suggest a unitary physical structure ('708 Patent, Fig. 5). The specification also refers to placing "A temperature sensing element" (singular) in each region, further supporting a narrow reading ('708 Patent, col. 6:41-42).
VI. Other Allegations
- Indirect Infringement: The complaint alleges inducement by claiming that HP's user guides, manuals, and website support instruct customers and resellers on how to use the infringing printers (Compl. ¶¶63, 65, 86, 88). It also makes allegations that may support a contributory infringement claim by asserting that the accused heater chip is a material part of the invention with no substantial non-infringing uses (Compl. ¶¶68, 91).
- Willful Infringement: Willfulness is alleged based on HP's purported pre-suit knowledge of the patents. For the ’823 patent, knowledge is alleged to date from the filing of a prior lawsuit (Case No. 6:19-cv-00549) (Compl. ¶62). For the ’708 patent, knowledge is alleged from at least December 11, 2019 (Compl. ¶85). The complaint alleges HP continued to infringe after gaining this knowledge.
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of claim construction and scope: can the terms "substantially centrally disposed" (’823 patent) and "single temperature sensing element" (’708 patent) be construed to read on the physical architecture of the accused HP heater chip? The resolution will likely depend on how the court defines these terms and on a factual analysis of the chip's design.
- A central evidentiary question will be one of functionality: does the physical component that Plaintiff identifies as a "temperature sensing element" actually perform the specific functions required by the claims—namely, sensing a representative temperature of a defined region and providing that information to a controller that in turn regulates heating in that same region? Proving this operational link, beyond the static structural layout shown in micrographs, will be critical for the plaintiff's case.