DCT
1:19-cv-00500
TPP Tech LLC v. Zebra Tech Corp
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: TPP Tech LLC (Texas)
- Defendant: Zebra Technologies Corporation (Delaware)
- Plaintiff’s Counsel: STAMOULIS & WEINBLATT LLC
- Case Identification: 1:19-cv-00500, D. Del., 03/13/2019
- Venue Allegations: Venue is alleged to be proper in the District of Delaware because the Defendant is a Delaware corporation and is therefore a resident of the district.
- Core Dispute: Plaintiff alleges that Defendant’s industrial thermal printers infringe two patents related to methods and systems for improving print quality by modeling and compensating for the thermal history of a printer’s print head.
- Technical Context: The technology addresses print quality degradation in thermal printers, such as "density drift," which arises from inaccurate assumptions about the print head's temperature during operation.
- Key Procedural History: The asserted patents share a specification and are part of the same patent family; U.S. Patent No. 7,825,943 is a divisional of the application that issued as U.S. Patent No. 7,295,224. The complaint alleges ownership by assignment but does not reference any prior litigation or administrative proceedings involving the patents.
Case Timeline
| Date | Event |
|---|---|
| 2001-08-22 | Earliest Priority Date for '224 and '943 Patents |
| 2007-11-13 | U.S. Patent No. 7,295,224 Issued |
| 2010-11-02 | U.S. Patent No. 7,825,943 Issued |
| 2019-03-13 | Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 7,295,224, "Thermal Response Correction System," issued Nov. 13, 2007
The Invention Explained
- Problem Addressed: The patent describes a problem in conventional thermal printers where individual print head elements retain heat from previous print cycles. This "thermal history" causes the actual temperature of a print head element to be higher than the fixed temperature assumed by the printer's control system, leading to inaccurate energy delivery and degraded print quality, such as "density drift" and blurred edges. (Compl. ¶8; ’224 Patent, col. 2:56-65).
- The Patented Solution: The invention proposes a system that actively models the thermal behavior of the print head. Instead of assuming a fixed starting temperature, it generates a prediction of each element's temperature at the beginning of a print cycle by accounting for factors like ambient temperature, humidity, and thermal history. (Compl. ¶9; ’224 Patent, Abstract). Based on this more accurate predicted temperature, the system calculates a corrected amount of energy to apply, thereby producing a more accurate and consistent printed image. (’224 Patent, col. 4:10-21).
- Technical Importance: This corrective approach was designed to improve image rendering accuracy by compensating for real-world operating conditions that conventional printers ignored, leading to sharper and more consistent output. (’224 Patent, col. 2:66-col. 3:2).
Key Claims at a Glance
- The complaint asserts independent method claim 1 and independent means-plus-function device claim 4. (Compl. ¶15).
- Independent Claim 1 recites a method with the essential steps of:
- Identifying a first print head temperature (
T_s). - Identifying a current ambient printer temperature (
T_r). - Identifying a modified print head temperature (
T_s') based on the first print head temperature and at least one property from the group consisting of the ambient temperature and current relative humidity. - Identifying an input energy to provide to a print head element in the print head based on the modified print head temperature.
- Identifying a first print head temperature (
- Independent Claim 4 recites a device comprising means for performing each of the functional steps outlined in method claim 1.
U.S. Patent No. 7,825,943, "Thermal Response Correction System," issued Nov. 2, 2010
The Invention Explained
- Problem Addressed: As a divisional of the '224 Patent's application, this patent addresses the same problem of thermal history in print heads causing inaccurate print densities. (’943 Patent, col. 2:1-18).
- The Patented Solution: The invention describes a method for computing the necessary input energy for a print head element based on its current temperature, ambient conditions (temperature and humidity), and, more specifically, "a plurality of one-dimensional functions of a desired output density." (’943 Patent, Abstract). This represents a specific computational approach for implementing the thermal correction, for example, by using a Taylor series expansion to model the energy requirement, which can be computationally efficient. (’943 Patent, col. 7:1-14).
- Technical Importance: The patent discloses a computationally efficient method to implement thermal correction logic, potentially reducing processing overhead while still providing the benefits of improved print quality. (’943 Patent, col. 13:52-64).
Key Claims at a Glance
- The complaint asserts independent claims 1 and 15, along with multiple dependent claims (11-13, 25-28). (Compl. ¶20).
- Independent Claim 1 recites a method with the essential step of:
- Computing an input energy based on (1) a current temperature of the print head element, (2) a plurality of one-dimensional functions of a desired output density, and (3) at least one property selected from ambient printer temperature and current humidity.
- Independent Claim 15 recites a thermal printer comprising a print head element and a "first computation means" for performing the computation described in method claim 1.
III. The Accused Instrumentality
- Product Identification: The complaint identifies the "Accused Instrumentality" as the 105SL Plus, ZT600, ZT510, and ZT400 Series Industrial Printers. (Compl. ¶14).
- Functionality and Market Context: The complaint provides minimal technical detail regarding the Accused Instrumentality. It alleges that the products are thermal printers that are made, used, sold, or offered for sale by the Defendant. (Compl. ¶14). The infringement allegations assert, in a conclusory manner, that the operation of these printers includes the specific steps and means recited in the asserted claims. (Compl. ¶¶16-17, 21-29). The complaint does not provide specific facts regarding the products' commercial importance beyond their identification as "Industrial Printers."
IV. Analysis of Infringement Allegations
No probative visual evidence provided in complaint.
- ’224 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| (A) identifying a first print head temperature T_s of a print head in a printer; | The complaint alleges that the Accused Instrumentality practices this step of identifying a print head temperature. | ¶16 | col. 8:46-51 |
| (B) identifying a current ambient temperature T_r in the printer; | The complaint alleges that the Accused Instrumentality practices this step of identifying an ambient printer temperature. | ¶16 | col. 9:19-22 |
| (C) identifying a modified print head temperature T_s' based on the first print head temperature T_s and at least one property selected from the group consisting of the ambient printer temperature T_r and a current relative humidity; | The complaint alleges that the Accused Instrumentality identifies a modified temperature based on the initial print head temperature and ambient conditions. | ¶16 | col. 12:16-30 |
| (D) identifying an input energy to provide to a print head element in the print head based on the modified print head temperature T_s'. | The complaint alleges that the Accused Instrumentality identifies the required input energy based on this modified temperature. | ¶16 | col. 12:45-56 |
- ’943 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| (A) computing an input energy to provide to the print head element based on a current temperature of the print head element, a plurality of one-dimensional functions of a desired output density to be printed by the print head element, and at least one property selected from the group consisting of an ambient printer temperature and a current humidity. | The complaint alleges that the Accused Instrumentality performs this computation, using the specified inputs to determine the energy to be provided to the print head element. | ¶21 | col. 7:1-14 |
- Identified Points of Contention:
- Factual Questions: A primary point of contention will be evidentiary. The complaint makes allegations by reciting claim language without providing specific facts about how the accused printers operate. The key question is whether discovery will produce evidence that the accused printers' software and hardware actually perform the specific temperature modeling and energy computation steps as claimed.
- Scope Questions: For the means-plus-function claims ('224 Claim 4 and '943 Claim 15), a dispute may arise over identifying the "corresponding structure" in the accused printers. Infringement will depend on whether the algorithms and hardware used in Zebra's printers are structurally equivalent to the specific embodiments disclosed in the patents, such as the described RC circuit models and computational formulas. (’224 Patent, col. 8:55-col. 9:8; Fig. 6).
- Technical Questions: A core technical question is whether the accused printers' control logic uses a "modified print head temperature" ('224 Patent) or computes energy via a "plurality of one-dimensional functions" ('943 Patent). The defense may argue that its printers use an alternative, structurally different algorithm to achieve thermal compensation, thereby avoiding infringement.
V. Key Claim Terms for Construction
The Term: "identifying a modified print head temperature T_s'" ('224 Patent, Claim 1)
- Context and Importance: This term is the core of the corrective method in the '224 patent. The method of arriving at this "modified" temperature is central to the infringement analysis. Practitioners may focus on this term because its construction will determine whether any temperature adjustment algorithm infringes, or only those that follow the patent's specific teachings.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent summary suggests the step is based on the print head temperature and the ambient temperature, without limiting the exact method of combination. (’224 Patent, col. 3:13-24).
- Evidence for a Narrower Interpretation: The detailed description discloses specific formulas for calculating
T_s', such asT_s' = T_s + f_1ΔT_randT_s' = T_s + f_1ΔT_r + f_h(T_r)ΔRH. (’224 Patent, col. 12:16-18, col. 13:37-39). A party may argue that these specific disclosed formulas define the scope of the claimed "identifying" step.
The Term: "a plurality of one-dimensional functions of a desired output density" ('943 Patent, Claim 1)
- Context and Importance: This term defines the specific mathematical model for computing energy in the '943 patent. Infringement hinges on whether the accused printers' algorithms utilize this type of computational structure.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The term itself does not specify the number of functions or how they are combined, only that there are at least two ("plurality") and that they are functions of density.
- Evidence for a Narrower Interpretation: The specification consistently describes this concept with a specific two-term additive formula,
E = G(d) + S(d)T_h, which it calls a "Taylor series expansion." (’943 Patent, col. 7:1-9). A party may argue that the claim term should be construed as being limited to this disclosed structure of separating the energy calculation into a density-only componentG(d)and a temperature-sensitive componentS(d)T_h.
VI. Other Allegations
- Indirect Infringement: The complaint alleges induced infringement, stating that Defendant provides "instruction manuals, advertisement of the infringing features, and support" that instruct and encourage customers and resellers to use the accused printers in a manner that directly infringes the asserted claims. (Compl. ¶36). It further alleges that Defendant specifically intends for its end-users to infringe through these activities. (Compl. ¶37).
- Willful Infringement: The complaint does not contain a separate count for willful infringement. However, in its inducement count, it alleges Defendant has had "knowledge of the Asserted Patents since at least the filing of this complaint" and acts with "knowledge or willful blindness to the fact that the induced acts would constitute infringement." (Compl. ¶¶37, 39). These allegations may form a basis for seeking enhanced damages for post-suit infringement.
VII. Analyst’s Conclusion: Key Questions for the Case
- A central issue will be one of evidentiary sufficiency: Given the complaint's lack of specific factual allegations mapping claim elements to accused product features, the case will depend heavily on whether Plaintiff can obtain evidence through discovery demonstrating that Zebra's printers in fact practice the claimed methods of temperature modeling and energy computation.
- A key legal dispute will be one of claim construction: The outcome will likely turn on the scope afforded to key terms. For the '224 patent, this is the meaning of "identifying a modified print head temperature," and for the '943 patent, the meaning of "a plurality of one-dimensional functions." The question is whether these terms can be read broadly to cover any algorithm achieving a similar result, or if they are limited to the specific mathematical embodiments disclosed in the patents.
- A critical question will be one of structural equivalence for the means-plus-function claims: For claims like '224 Claim 4 and '943 Claim 15, the analysis will focus on whether the specific algorithms used in Zebra's printers are structurally equivalent to the corresponding structures disclosed in the patent specifications, such as the RC circuit models and explicit formulas, or if they represent a different and non-equivalent technical implementation.