DCT

1:25-cv-08460

Guangzhou Yuehong Technology Co Ltd v. Buffalo Games LLC

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Key Events
Complaint

I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:25-cv-08460, S.D.N.Y., 10/14/2025
  • Venue Allegations: Plaintiff alleges venue is proper because Defendant is subject to personal jurisdiction in the district, having previously filed a lawsuit in the S.D.N.Y. to enforce the same patent against a different party.
  • Core Dispute: Plaintiff seeks a declaratory judgment that its "Writing Tablet for Kids" products do not infringe Defendant's patent related to multicolored pressure-sensitive liquid crystal devices, and that the patent is invalid.
  • Technical Context: The technology concerns electronic writing tablets that use cholesteric liquid crystal displays to create multicolored images in response to pressure from a stylus, aiming to replicate the experience of writing with colored pens on paper in a reusable, low-power format.
  • Key Procedural History: The action was precipitated by Defendant's initiation of an Amazon Patent Evaluation Express (APEX) proceeding against Plaintiff, alleging infringement. The complaint also notes a prior lawsuit filed by Defendant in the same district to enforce the patent-in-suit against another competitor, which is used here to support venue allegations.

Case Timeline

Date Event
1985-06-25 Issue Date of U.S. Patent No. 4,525,032 ("Cyril"), cited as prior art
2000-08-15 Issue Date of U.S. Patent No. 6,104,448 ("Doane"), cited as prior art
2012-03-20 Issue Date of U.S. Patent No. 8,139,039 ("Schneider"), cited as prior art
2012-05-03 Publication Date of WO 2012/058311 ("Pishnyak"), cited as prior art
2012-10-30 Issue Date of U.S. Patent No. 8,300,183 ("Yao-Dong"), cited as prior art
2013-11-28 Publication Date of US 2013/0314621 ("Montbach"), cited as prior art
2015-12-16 Priority Date of ’672 Patent
2018-03-27 Issue Date of U.S. Patent No. 9,927,672
2025-09-24 Defendant initiated APEX process against Plaintiff
2025-10-14 Complaint for Declaratory Judgment filed

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

U.S. Patent No. 9,927,672 - Multicolored pressure sensitive liquid crystal device

The Invention Explained

  • Problem Addressed: The patent background describes a market need for low-cost, rugged, low-power electronic writing tablets that can capture and display handwriting and drawings in multiple vibrant colors, mimicking the use of colored pens and paper without the associated waste and mess (’672 Patent, col. 1:7-25). Existing single-color devices lacked the visual appeal of multicolored drawing (’672 Patent, col. 1:8-11).
  • The Patented Solution: The invention is a pressure-sensitive device using a single layer of cholesteric liquid crystal material disposed between two substrates. This liquid crystal layer is engineered to have distinct regions that are tuned to reflect different colors of light. When a user applies pressure with a stylus, the liquid crystal in that location changes its optical state from transparent to reflective, revealing a colored mark. Because different areas of the screen are designed to reflect different colors, a single stroke of the stylus can produce a line that changes color as it crosses from one region to another (’672 Patent, Abstract; col. 12:1-15). This approach achieves a multicolor effect without requiring stacked display layers or complex electronics (’672 Patent, col. 5:28-32).
  • Technical Importance: The invention purports to provide a method for creating a multicolor electronic writing experience in a simple, single-layer device structure, potentially reducing manufacturing complexity and cost compared to alternative multicolor display technologies (’672 Patent, col. 8:17-21).

Key Claims at a Glance

  • The complaint identifies independent claim 24 as the basis of Defendant's infringement allegation (Compl. ¶2).
  • The essential elements of independent claim 24 are:
    • A first transparent, flexible substrate and a second substrate spaced apart.
    • First and second electrically conductive layers disposed between the substrates.
    • A pressure sensitive liquid crystal layer comprising a dispersion of cholesteric liquid crystal and polymer.
    • The liquid crystal layer includes at least a first region and a second region that differ from each other in at least one characteristic such as reflectivity, linewidth, or electrooptic response.
    • Pressure applied to the first substrate causes a change in reflectance, displaying a first characteristic over the first region and a second characteristic over the second region to form an image.

III. The Accused Instrumentality

Product Identification

Plaintiff's "Writing Tablet for Kids" products, including the "4 Pack LCD Writing Tablet for Kids, 8.5 Inch Colorful Doodle Board Drawing Tablet" (Compl. ¶¶1, 14).

Functionality and Market Context

  • The complaint describes the accused product as a children's writing and drawing tablet sold on Amazon (Compl. ¶8). A screenshot provided in the complaint shows a device with a stylus that creates multicolored lines on a dark background (Compl. at 4).
  • The product is alleged to be highly popular, ranking as a "#1 Best Seller" in the "Kids' Doodle & Scribbler Boards" category on Amazon (Compl. ¶15). The screenshot from the Amazon product listing shows the tablet displaying a drawing of a dinosaur with lines that appear to be yellow, green, and blue, illustrating its multi-color capability (Compl. at 4).

IV. Analysis of Infringement Allegations

The complaint, being an action for declaratory judgment of non-infringement, does not contain a detailed breakdown of how the accused product allegedly infringes the ’672 Patent. Instead, it states that the Defendant initiated an APEX proceeding asserting that the Plaintiff's Writing Tablet infringes Claim 24 (Compl. ¶14). The complaint makes a general denial of infringement, alleging the product "lacks one or more elements required by Claim 24" but does not specify which elements are missing (Compl. ¶35). The complaint does not provide sufficient detail for a claim-by-claim analysis of the infringement allegations.

  • Identified Points of Contention:
    • Scope Questions: A central dispute will likely concern whether the mechanism used in the accused "Writing Tablet for Kids" to produce multiple colors is the same as that covered by Claim 24. Specifically, does the accused product contain a single liquid crystal layer with "at least a first region and a second region" that "differ from each other" in a claimed characteristic, or does it achieve a multicolor effect through an alternative, non-infringing design?
    • Technical Questions: As the complaint focuses heavily on invalidity, it provides no technical detail on the accused product's construction. A key evidentiary question for the court will be to determine the actual structure and principle of operation of the accused tablet and compare it to the specific limitations of Claim 24.

V. Key Claim Terms for Construction

  • The Term: "a first region and a second region"
  • Context and Importance: This term is the core of the invention's multicolor capability. The definition of what constitutes distinct "regions" within a single liquid crystal layer will be critical to determining both infringement and validity. Practitioners may focus on this term because its scope dictates whether the patent covers only devices with sharply defined color zones or also those with gradual color transitions.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification suggests that the regions need not be discrete or have sharp boundaries. It states that "the change in color at the boundary of color regions 62 and 63 need not be a step function of green to red, but the color can gradually change from green to yellow to red" (’672 Patent, col. 12:60-63). This could support a construction that includes continuous color gradients.
    • Evidence for a Narrower Interpretation: The patent's figures and primary embodiments describe distinct, patterned areas. Figure 7A shows parallel stripes (61, 62, 63), and Figure 9 shows "islands of various sizes and shapes" (71, 72, 73) (’672 Patent, col. 10:37-39; Fig. 9). This could support a narrower construction limited to physically distinct and patterned zones of color-reflecting material.

VI. Other Allegations

The complaint does not contain allegations of indirect or willful infringement.

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

  • A primary issue will be one of validity in view of the prior art: The complaint presents a detailed obviousness argument, asserting that a person of ordinary skill in the art in 2015 would have been motivated to combine prior art teachings of pressure-sensitive cholesteric devices (e.g., "Cyril") with known techniques for creating multicolor regions in liquid crystal layers (e.g., "Schneider") (Compl. ¶28). The case may turn on whether this combination would have been obvious or required an inventive step.
  • A central question of claim scope will be determinative for infringement: Can the claim term "a first region and a second region" be construed to cover the specific method of color generation employed by the accused product? The resolution of this construction will likely define the boundary between infringement and non-infringement for this type of multicolor writing tablet technology.