DCT
6:20-cv-00048
Slingshot Printing LLC v. HP
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: *Slingshot Printing LLC v. HP Inc.*, 6:20-cv-00048, W.D. Tex., 01/23/2020
- 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, and employs numerous individuals there.
- Core Dispute: Plaintiff alleges that Defendant’s inkjet printers, and specifically the thermal management systems within their printhead heater chips, infringe patents related to regulating the temperature of such chips to ensure print quality.
- Technical Context: The technology concerns precise temperature control in inkjet printhead chips, where heating elements are used to manage ink viscosity for consistent droplet ejection, a critical factor for achieving high-resolution printing.
- Key Procedural History: The patents-in-suit, originally assigned to Lexmark International, Inc., were acquired by Funai Electric Co., Ltd. and subsequently assigned to Plaintiff Slingshot. The complaint alleges that Defendant had pre-suit knowledge of the ’823 patent from prior litigation (Slingshot Printing LLC v. HP Inc., Case No. 6:19-cv-00549) and of the ’708 patent as of December 11, 2019.
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 Issues |
| 2009-09-29 | U.S. Patent No. 7,594,708 Issues |
| 2019-12-11 | Alleged Notice Date for ’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 describes a problem in prior art inkjet heater chips, particularly those designed for high resolution by placing heating elements on both sides of an ink supply channel (a "via"). Traditional temperature sensors either provided only a crude average temperature for the whole chip or, when placed too close to individual heaters, suffered from thermal "crosstalk" that led to inaccurate readings and poor temperature regulation between different color regions. (’823 Patent, col. 1:48 - col. 2:54).
- The Patented Solution: The invention proposes a new chip architecture to solve this. It places a temperature sensing element within the silicon region between two separate heater arrays (which themselves are adjacent to two different ink vias). This sensor is "substantially centrally disposed" in that region, keeping it away from the direct influence of either heater. This configuration allows the sensor to measure the temperature of that specific region accurately, enabling a control system to apply heating pulses to maintain an optimal, stable temperature for consistent ink ejection. (’823 Patent, Abstract; col. 2:56-65).
- Technical Importance: This design enabled more granular and precise thermal management across a printhead, which is a key factor in improving print quality and speed by ensuring uniform ink drop size and weight. (’823 Patent, col.1:41-47).
Key Claims at a Glance
- The complaint asserts independent claim 1 and dependent claims 2, 5-9, as well as method claims 11, 12, and 15-17 (Compl. ¶41, ¶61).
- Independent Claim 1 recites a chip comprising:
- 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 to sense the temperature of the region, where the element is "substantially centrally disposed" with respect to the region, is adjacent to both heater arrays, and "extends substantially the length" of the heater arrays.
- The heater arrays are operable to receive heating responsive to the sensed temperature 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 patent addresses the same technical challenge as the ’823 patent: the difficulty of accurate temperature sensing and control in high-density printheads where multiple heater arrays are positioned between parallel ink vias. (’708 Patent, col. 1:41 - col. 2:54).
- The Patented Solution: This invention defines a specific chip layout comprising parallel ink vias, each flanked on its longitudinal sides by heater arrays. The key inventive concept is the definition of a "region" that exists between two adjacent ink vias. This region, therefore, contains two heater arrays (one associated with each adjacent via). The patent teaches placing a single temperature sensing element within this defined region, at a "predetermined distance" from the heaters, to measure a temperature that is "representative of the heater arrays adjacent to the region." (’708 Patent, Abstract; col. 8:26-42).
- Technical Importance: This architecture provides a systematic framework for partitioning a multi-color printhead into discrete thermal zones, each monitored by a dedicated sensor, facilitating precise control over the entire printing apparatus. (’708 Patent, col. 6:20-33).
Key Claims at a Glance
- The complaint asserts independent claim 1 and dependent claims 2, 5-8, as well as method claims 9-10 and 14-15 (Compl. ¶71, ¶84).
- Independent Claim 1 recites a chip comprising:
- A plurality of parallel ink vias, each with two longitudinal sides.
- A heater array disposed adjacent to each longitudinal side of the ink vias.
- A "region" disposed between two adjacent ink vias, where the region includes two heater arrays.
- A "single temperature sensing element" disposed within each region, operable to sense a temperature representative of the adjacent heater arrays, and disposed at a "predetermined distance" away from them.
III. The Accused Instrumentality
Product Identification
- The complaint identifies HP's inkjet printers, using the HP OfficeJet Pro 6978 as an exemplary product. The infringement allegations focus on the "tricolor heater chip" contained within the printer's ink cartridge or printhead assembly (Compl. ¶¶ 41, 44, 74).
Functionality and Market Context
- The complaint alleges that the accused tricolor heater chip contains multiple heater arrays, ink vias, and temperature sensors arranged in a specific physical layout. The function of these components is to heat ink to control its viscosity for ejection from printhead nozzles, with the temperature sensors providing feedback to a main controller board that regulates the heating process (Compl. ¶¶ 48-49, 58, 78, 82). The complaint supports these allegations with annotated micrograph images of the accused chip die. A micrograph showing the alleged first and second heater arrays with a region between them is provided in the complaint (Compl. ¶47, p. 16). The complaint also provides an image of the main controller board alleged to be the "control element" that regulates the heating (Compl. ¶58, p. 21).
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 tricolor heater chip has a first heater array positioned next to a first ink via, as depicted in a micrograph. A visual shows the labeled "First heater array" and "First ink via" (Compl. ¶45, p. 15). | ¶45 | col. 11:46-47 |
| a second heater array positioned substantially adjacent a second via; | The chip has a second heater array positioned next to a second ink via. | ¶46 | col. 11:48-49 |
| a region, positioned between the first heater array and the second heater array, and also positioned substantially adjacent to the first heater array and the second heater array; | The chip has a region located between the first and second heater arrays, as shown in an annotated micrograph. | ¶47 | col. 11:50-54 |
| 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 substantially adjacent to both the first heater array and second heater array... | The chip has a temperature sensing element, shown in micrographs, that is alleged to be centrally disposed within the region and adjacent to both heater arrays. A visual shows this element highlighted between the arrays (Compl. ¶48, p. 17). | ¶48 | col. 11:55-63 |
| wherein the first heater array and the second heater array are operable to receive heating responsive to the temperature of the region sensed by the temperature sensing element, and wherein the received heating regulates the temperature of the region. | The heater arrays are operable to receive heating based on the temperature measured by the sensor, which is managed by a main controller board, to regulate the region's temperature. | ¶¶49, 58 | col. 11:64 - col. 12:2 |
’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 of the ink via having two longitudinal sides; | The tricolor heater chip contains multiple ink vias arranged in parallel, as shown in a micrograph where three such vias are identified (Compl. ¶75, p. 26). | ¶75 | col. 11:27-29 |
| a heater array disposed adjacent each longitudinal side of the ink vias such that each ink via is associated with two heater arrays disposed adjacent the two longitudinal sides of the ink via; | The chip has heater arrays positioned along each side of the ink vias. | ¶76 | col. 11:30-34 |
| 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 each heater array being associated with their respective ink via; and | The chip has a region between adjacent ink vias, and this region includes two heater arrays associated with their respective vias. A visual shows these regions highlighted on the chip die (Compl. ¶77, p. 26-27). | ¶77 | col. 11:35-40 |
| a single temperature sensing element disposed within each region, the temperature sensing element operable to sense a temperature representative of the heater arrays adjacent to the region and disposed at a predetermined distance away from adjacent heater arrays. | The chip has a single temperature sensing element within the region, which is alleged to sense the temperature of the adjacent arrays and is positioned at a distance away from them. | ¶78 | col. 11:41-47 |
Identified Points of Contention
- Scope Questions: The dispute may center on the construction of relative or qualitative terms. For the ’823 patent, the meaning of "substantially centrally disposed" and what it means for the sensor to "extend substantially the length" of the heater arrays will be critical. For the ’708 patent, the scope of "predetermined distance" and "single temperature sensing element" will likely be contested.
- Technical Questions: A central evidentiary question for both patents will be whether the accused sensor performs the claimed function. The complaint alleges the sensor measures a temperature "representative of the region" or "representative of the heater arrays". Defendant may argue that its sensor simply measures the bulk temperature of the silicon substrate, a technically distinct function from the specific, localized regional monitoring described and claimed in the patents. The ability of Plaintiff to prove this functional aspect of infringement, beyond showing physical placement, will be key.
V. Key Claim Terms for Construction
Term ("’823 Patent, Claim 1"): "substantially centrally disposed"
Context and Importance
- This term of degree is central to the infringement analysis for the ’823 patent. Infringement will depend on whether the accused sensor's physical placement on the chip die is determined to be "central enough." Practitioners may focus on this term because its interpretation will define the spatial tolerance allowed by the claim.
Intrinsic Evidence for Interpretation
- Evidence for a Broader Interpretation: The specification suggests some flexibility, stating that sensors "can be positioned at any point within their respective thermal regions" ('823 Patent, col. 7:8-11), which could support a construction that does not require perfect geometric centering.
- Evidence for a Narrower Interpretation: The patent repeatedly emphasizes the goal of avoiding inaccurate readings caused by proximity to a single heater. The description notes that remaining sensors "are centered between heater arrays from adjacent ink vias" ('823 Patent, col. 7:1-3). This purpose—to achieve an accurate regional reading by being equidistant from heat sources—may support a narrower construction requiring a placement that is close to geometrically central.
Term ("’708 Patent, Claim 1"): "a single temperature sensing element disposed within each region"
Context and Importance
- This term defines the one-sensor-per-region architecture of the ’708 patent. The validity of the infringement theory rests on the accused chip having this precise configuration.
Intrinsic Evidence for Interpretation
- Evidence for a Broader Interpretation: A party might argue "single" does not preclude the existence of other, secondary sensing components, as long as there is one primary element as described.
- Evidence for a Narrower Interpretation: The plain language and consistent use of the singular "a single temperature sensing element" throughout the patent strongly suggest a "one and only one" construction. The patent's solution is to simplify and improve accuracy by using one well-placed sensor per region, contrasting with prior art that was either too simplistic (one sensor for the whole chip) or too complex. This supports a narrow interpretation. (’708 Patent, col. 6:40-45).
VI. Other Allegations
Indirect Infringement
- The complaint alleges inducement of infringement, stating that HP provides user guides, manuals, and website support that instruct customers and resellers on how to use the accused printers in an infringing manner (Compl. ¶¶ 63, 65, 86, 88). It is also alleged that the heater chip is a material component of the invention with no substantial non-infringing uses, forming a basis for contributory infringement (Compl. ¶¶ 68, 91).
Willful Infringement
- Willfulness is alleged based on pre-suit knowledge. For the ’823 patent, Plaintiff alleges knowledge arises from a prior lawsuit, Slingshot Printing LLC v. HP Inc., Case No. 6:19-cv-00549 (Compl. ¶62). For the ’708 patent, Plaintiff alleges HP was on notice as of December 11, 2019 (Compl. ¶85).
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of definitional scope: can the qualitative terms in the claims, such as "substantially centrally disposed" (’823 patent) and "predetermined distance" (’708 patent), be construed in a way that encompasses the physical layout of the accused HP chip? The outcome will depend heavily on the court's claim construction.
- A key evidentiary question will be one of functional operation: does the accused temperature sensor perform the specific function required by the claims—sensing a temperature "representative" of a defined thermal region—or does it perform a more general function, such as measuring the bulk temperature of the silicon substrate? Proving this functional equivalence, beyond mere structural similarity, will be a central challenge for the plaintiff.
- The case will also involve a question of architectural mapping: can the plaintiff successfully demonstrate that the complex, multi-layered structures of the accused HP chip align with the specific via, heater, and region architectures recited in the claims? While the complaint's micrographs provide a starting point, the precise boundaries and relationships of these elements will be a likely point of factual dispute.