DCT

2:24-cv-00646

Light Guide Innovations LLC v. TCT Mobile Intl Ltd

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 2:24-cv-00646, E.D. Tex., 08/08/2024
  • Venue Allegations: Plaintiff alleges venue is proper because the Defendants are foreign companies that may be sued in any judicial district, and that they are subject to personal jurisdiction in the Eastern District of Texas through their business activities.
  • Core Dispute: Plaintiff alleges that Defendant’s LED, QLED, and QD-MINI LED televisions and displays infringe fourteen patents related to LED backlight assemblies, including technologies for connecting LED substrates, thermal management, lens design, and photoluminescent sheets.
  • Technical Context: The patents relate to the design and construction of LED backlight units, which are fundamental components in modern LCD televisions and displays that determine brightness, color accuracy, and energy efficiency.
  • Key Procedural History: The complaint alleges that the patents-in-suit were originally developed by LG Innotek and later sold to Suzhou Lekin Semiconductor. Plaintiff asserts that this sale was "widely publicized," forming a basis for its willful infringement allegations.

Case Timeline

Date Event
2006-03-15 Priority Date for ’411 and ’352 Patents
2006-08-24 Priority Date for ’415 Patent
2006-12-29 Priority Date for ’091 Patent
2007-11-06 Priority Date for ’380 Patent
2009-05-13 Priority Date for ’200 Patent
2009-11-19 Priority Date for ’122, ’307, ’729, and ’378 Patents
2009-11-20 Priority Date for ’744, ’048, and ’183 Patents
2011-04-12 U.S. Patent No. 7,922,380 Issues
2011-05-03 U.S. Patent No. 7,936,415 Issues
2011-10-25 U.S. Patent No. 8,045,091 Issues
2011-11-08 U.S. Patent No. 8,052,307 Issues
2012-07-03 U.S. Patent No. 8,213,093 Issues (Note: Not asserted in a specific count)
2012-08-07 U.S. Patent No. 8,237,352 Issues
2013-03-12 U.S. Patent No. 8,395,183 Issues
2013-08-13 U.S. Patent No. 8,506,122 Issues
2013-10-22 U.S. Patent No. 8,562,200 Issues
2013-12-31 U.S. Patent No. 8,616,729 Issues
2014-05-13 U.S. Patent No. 8,723,411 Issues
2014-09-02 U.S. Patent No. 8,823,048 Issues
2017-01-03 U.S. Patent No. 9,534,744 Issues
2017-05-02 U.S. Patent No. 9,638,378 Issues
2024-08-08 Complaint Filed

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

U.S. Patent No. 7,936,415 - “Light Source Apparatus And Liquid Crystal Display Having The Same”

  • Issued: May 3, 2011

The Invention Explained

  • Problem Addressed: The patent addresses the need for improved mechanical and electrical connection structures for the LED module substrates used in backlight units (Compl. ¶26; ’415 Patent, col. 1:26-34).
  • The Patented Solution: The invention describes a light source apparatus where multiple LED "module substrates" (e.g., LED strips) are connected using "connecting substrates." A key feature is a "termination connecting substrate" that connects to the final module substrate in a series, creating what the patent calls a "closed loop circuit" (’415 Patent, Abstract; col. 4:38-42). This configuration aims to improve electrical reliability and mechanical strength between the LED modules (’415 Patent, col. 2:1-6).
  • Technical Importance: This approach can simplify the assembly of large-area direct-lit backlight units by providing a robust method for daisy-chaining multiple LED strips.

Key Claims at a Glance

  • The complaint asserts at least independent claim 1 (Compl. ¶43).
  • Claim 1 Elements:
    • at least one module substrate comprising connecting terminals at both side ends thereof;
    • a light emitting diode on the module substrate; and
    • a plurality of connecting substrates connected to the connecting terminals of the module substrate,
    • wherein the connecting substrate comprises a termination connecting substrate, by which the connecting terminal provided at one end of a final module substrate of the module substrates is prepared as a closed loop circuit.
  • The complaint does not explicitly reserve the right to assert dependent claims for this patent.

U.S. Patent No. 7,922,380 - “Light Unit And Display Device Having The Same”

  • Issued: April 12, 2011

The Invention Explained

  • Problem Addressed: The patent addresses the need for improved heat conduction and dissipation in light-emitting modules for display devices, a critical factor for LED longevity and performance (Compl. ¶29; ’380 Patent, col. 1:31-34).
  • The Patented Solution: The invention discloses a light unit assembly where light-emitting devices are mounted on a flexible printed circuit board (PCB). This board is attached to a metal plate that contacts the device housing, creating a thermal pathway to dissipate heat (’380 Patent, Abstract; col. 2:50-54, col. 2:66-col. 3:2). Claim 1 details a specific spatial arrangement where the flexible PCB has a first portion between the metal plate and a light guide member, and a second portion between a reflection sheet and the housing (’380 Patent, col. 6:53-65).
  • Technical Importance: This integrated design provides a method for managing heat in slim display assemblies while defining a specific structural relationship between the optical and electronic components.

Key Claims at a Glance

  • The complaint asserts at least independent claim 1 (Compl. ¶56).
  • Claim 1 Elements:
    • a light guide member outputting surface light upward;
    • a board disposed to a first side of the light guide member;
    • a plurality of light-emitting devices mounted on a first side of the board;
    • a reflection sheet under the light guide member;
    • a housing receiving the light guide member, the light-emitting devices, the board, and the reflection sheet; and
    • a metal plate attached to a second side of the board and a first side of the housing,
    • wherein the second side of the board is opposite to the first side of the board,
    • wherein a lower side of the metal plate is contacted with a bottom surface of the housing,
    • wherein the board is a flexible PCB that includes a first portion disposed between the metal plate and the first side of the light guide member, and a second portion disposed between the reflection sheet and the housing, and
    • wherein the second portion of the board includes line patterns connected to the light-emitting devices.
  • The complaint does not explicitly reserve the right to assert dependent claims for this patent.

U.S. Patent No. 8,562,200 - “Lighting Module, Backlight Unit, And Display Device Including The Same”

  • Issued: October 22, 2013
  • Technology Synopsis: The patent describes a lighting module with a guide protrusion on the substrate surface. This protrusion, comprising a pin and a cap, is designed to have a height less than the light emitting diodes, potentially for alignment or structural purposes within a backlight assembly (Compl. ¶27, ¶78).
  • Asserted Claims: At least independent claim 1 (Compl. ¶77).
  • Accused Features: The guide protrusions allegedly visible beneath the optics on the LED strips of the accused televisions (Compl. ¶81).

U.S. Patent No. 8,045,091 - “Backlight Unit And Display Device Having The Same”

  • Issued: October 25, 2011
  • Technology Synopsis: This patent addresses a backlight unit construction aimed at improving brightness uniformity. It discloses an LED module fixed to a case, a reflective sheet with an opening for the LED, and a guide pin. The reflective sheet includes a recess to accommodate a protrusion from the fixing part, which may allow for a flatter, more uniform reflective surface (Compl. ¶28, ¶92).
  • Asserted Claims: At least independent claim 1 (Compl. ¶91).
  • Accused Features: The assembly of LED strips, the TV case, screws or tabs (fixing parts), a reflective sheet, and guide pins within the accused products (Compl. ¶93-98).

U.S. Patent No. 8,506,122 - “Lens And Light Emitting Apparatus Having The Same”

  • Issued: August 13, 2013
  • Technology Synopsis: The technology relates to a lens for a light emitting apparatus designed to shape light output. The lens body has a first recess on its top surface and a second recess on its bottom surface, and is held off the substrate by a lens support, which may enhance lateral light emission (Compl. ¶30, ¶108).
  • Asserted Claims: At least independent claim 1 (Compl. ¶107).
  • Accused Features: The optics (lenses) disposed over the LED packages on the LED strips of the accused products (Compl. ¶111-112).

U.S. Patent No. 8,052,307 - “Lens And Light Emitting Apparatus Having The Same”

  • Issued: November 8, 2011
  • Technology Synopsis: Similar to the ’122 Patent, this invention describes a light emitting apparatus with a specific lens structure. It includes an LED package with a phosphor and sealing resin layer, and a lens with top and bottom recesses supported above the substrate to control light distribution (Compl. ¶122). The complaint asserts this patent twice, in Counts VI and VIII, against different accused products and with different claim language cited, suggesting a potential clerical error in the complaint regarding the patent number in Count VIII.
  • Asserted Claims: At least independent claim 1 (Compl. ¶121, ¶148).
  • Accused Features: The LED packages and associated lenses on the LED strips of accused televisions (Compl. ¶124-126, ¶150-151).

U.S. Patent No. 8,616,729 - “Lens And Light Emitting Apparatus Having The Same”

  • Issued: December 31, 2013
  • Technology Synopsis: This patent details a lens with specific geometric ratios. It claims a lens body with a convex top surface having a recessed central part, a flat bottom surface with a second recessed part, and a plurality of lens supports. The invention is defined by a specific claimed ratio of the first recess depth to the overall lens thickness (Compl. ¶136).
  • Asserted Claims: At least independent claim 1 (Compl. ¶135).
  • Accused Features: The lenses on the LED strips of accused televisions, which allegedly meet the claimed geometric ratios (Compl. ¶137-139).

U.S. Patent No. 9,534,744 - “Light Emitting Apparatus”

  • Issued: January 3, 2017
  • Technology Synopsis: This invention concerns a lens with specific dimensional constraints. It claims a lens with a convex top surface including a first recessed part, where the flat top surface is lower than the lowest point of the recess. It further specifies ranges for the maximum width of the curved portion, the maximum width of the lens body, and ratios of recess depth and width to lens thickness and width (Compl. ¶163).
  • Asserted Claims: At least independent claim 1 (Compl. ¶162).
  • Accused Features: The lenses on the LED strips of accused televisions, which are alleged to meet the claimed dimensional and ratio limitations (Compl. ¶164-166).

U.S. Patent No. 8,823,048 - “Light Emitting Apparatus”

  • Issued: September 2, 2014
  • Technology Synopsis: This patent describes a lens with distinct center, peripheral, and side portions. The center portion has top and bottom recesses, with the top recess being inwardly-concave and wider than the bottom recess. The peripheral portion has a rounded-top surface that creates a continuing surface between the center and side portions (Compl. ¶176).
  • Asserted Claims: At least independent claim 1 (Compl. ¶175).
  • Accused Features: The optics disposed over the LEDs in accused products, which allegedly have the claimed center, peripheral, and side portion structures (Compl. ¶179-180).

U.S. Patent No. 8,395,183 - “Light Emitting Apparatus”

  • Issued: March 12, 2013
  • Technology Synopsis: The invention relates to a light emitting apparatus including a fluorescent layer and an encapsulant resin layer over the LED. It claims a lens with a downwardly concave first recess on top and an upwardly concave second recess on the bottom, supported off the substrate. A key feature is a specific ratio of the maximum depth of the first recess to the second recess (Compl. ¶196).
  • Asserted Claims: At least independent claim 1 (Compl. ¶195).
  • Accused Features: The LED packages (with encapsulant and phosphor) and lenses on the LED strips of accused televisions, which allegedly have the claimed lens geometry and depth ratios (Compl. ¶199-204).

U.S. Patent No. 9,638,378 - “Light Emitting Apparatus”

  • Issued: May 2, 2017
  • Technology Synopsis: This patent is similar to the '744 patent, describing a lens with specific dimensional and positional constraints. It claims a lens where the flat top surface is lower than both the lowest point of the first (top) recess and the highest point of the second (bottom) recess, in addition to specific width and width-ratio limitations (Compl. ¶214).
  • Asserted Claims: At least independent claim 1 (Compl. ¶213).
  • Accused Features: The lenses on the LED strips of certain accused televisions, which are alleged to have the specific geometric and positional features claimed (Compl. ¶215-220).

U.S. Patent No. 8,723,411 - “Photoluminescent Sheet”

  • Issued: May 13, 2014
  • Technology Synopsis: The technology concerns a photoluminescent sheet, such as a quantum dot enhancement film (QDEF). The invention claims a sheet with a resin layer containing a phosphor, sandwiched between two protective films of uniform thickness made of a transparent synthetic resin. A key limitation is that the two protective films comprise "at least one same material" (Compl. ¶31, ¶230).
  • Asserted Claims: At least independent claim 1 (Compl. ¶229).
  • Accused Features: The quantum dot television models, which allegedly use a photoluminescent sheet with a resin layer (quantum dot layer) and top and bottom barrier films made of the same material (e.g., PET) (Compl. ¶231-234).

U.S. Patent No. 8,237,352 - “Photoluminescent Sheet”

  • Issued: August 7, 2012
  • Technology Synopsis: This patent also relates to a photoluminescent sheet. It claims a sheet comprising a resin layer with a phosphor, a curing agent, and an additive for dispersion. The sheet is protected by top and bottom films of a transparent synthetic resin that is "not curable by light" (Compl. ¶31, ¶244).
  • Asserted Claims: At least independent claim 1 (Compl. ¶243).
  • Accused Features: The quantum dot televisions, which allegedly employ a sheet with a resin layer containing a UV curing agent and additives, and protective barrier films (e.g., PET) that are not themselves curable by light (Compl. ¶245-249).

III. The Accused Instrumentality

Product Identification

  • The complaint broadly accuses "all LED, QLED, and QD-MINI LED televisions or displays" sold by the Defendants, specifically naming the S2, S3, S4, S5, 3-Series, 4-Series, C8-Series, P6-Series, S-Series, Q-Class, Q5, Q6, Q7, QM7, QM8, and NXTFRAME product lines and their backlight components (Compl. ¶32). Specific models like the 3-Series 40S325, 4-Series 55S401, S-Series 55US57, and Q6 75Q691F are identified as exemplary infringing products for certain patents (Compl. ¶43, ¶56, ¶77, ¶229).

Functionality and Market Context

  • The accused products are televisions and displays that use direct-lit LED backlights for illumination. The complaint uses screenshots from teardown videos to illustrate the internal components, including rows of LED strips mounted to a metal plate inside the television housing, covered by a white reflective sheet, with individual optics (lenses) over each LED (Compl. ¶58-63). A photo from a teardown of a TCL television shows an array of these LED strips (Compl. p. 18, ¶58). Certain higher-end models, such as the Q6 series, are alleged to incorporate a "photoluminescent sheet including a resin layer" (a quantum dot enhancement film) between the backlight and the LCD panel to enhance color performance (Compl. ¶231).
  • The complaint alleges that Defendants are leading manufacturers and sellers of televisions in the United States, citing a 2022 annual report stating that TCL ranked "a solid No.2 in the U.S." in terms of retail sales volume (Compl. ¶3-6, ¶37).

IV. Analysis of Infringement Allegations

U.S. Patent No. 7,936,415 - Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
at least one module substrate comprising connecting terminals at both side ends thereof; The accused products contain rows of module substrates, such as LED strips, which have connecting terminals at both ends. ¶45 col. 7:3-5
a light emitting diode on the module substrate; and Each LED strip in the accused products contains multiple light emitting diodes. ¶46 col. 7:6-6
a plurality of connecting substrates connected to the connecting terminals of the module substrate, The accused products use connecting substrates to connect the terminals at the ends of the module substrates, forming chained rows of LED strips. ¶47 col. 7:7-9
wherein the connecting substrate comprises a termination connecting substrate, by which the connecting terminal provided at one end of a final module substrate of the module substrates is prepared as a closed loop circuit. The series of chained LED strips allegedly forms a closed loop circuit within each row, meeting the termination requirement. An image shows the end connectors on the LED strips (Compl. p. 14, ¶47). ¶47 col. 7:10-14
  • Identified Points of Contention:
    • Scope Questions: A primary point of contention may be the construction of "closed loop circuit." The defense may argue that a standard serial or "daisy-chain" connection of LED strips does not constitute the specific "termination connecting substrate" that creates a "closed loop circuit" as described and depicted in the patent's embodiments (e.g., ’415 Patent, Fig. 8), which may imply a feedback or return path rather than a simple series termination.

U.S. Patent No. 7,922,380 - Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
a light guide member outputting surface light upward; The individual optic mounted over each LED on an LED strip. ¶58 col. 5:35-37
a board disposed to a first side of the light guide member; The LED strip itself, on which the optic is mounted. ¶59 col. 6:46-47
a plurality of light-emitting devices mounted on a first side of the board; The LEDs mounted on the surface of the LED strip. ¶60 col. 5:54-55
a reflection sheet under the light guide member; A white reflective sheet situated under the optics. ¶61 col. 5:21-22
a housing receiving the light guide member, the light-emitting devices, the board, and the reflection sheet; and The plastic and/or metal outer housing of the television that contains the backlight assembly. ¶62-63 col. 6:49-51
a metal plate attached to a second side of the board and a first side of the housing, A metal plate located between the LED strip and the television's outer housing. A screenshot from a video shows this metal plate being lifted with the LED strip (Compl. p. 21, ¶64). ¶64 col. 5:52-53
...wherein the board is a flexible PCB that includes a first portion disposed between the metal plate and the first side of the light guide member, and a second portion disposed between the reflection sheet and the housing... The LED strips are alleged to be flexible PCBs with portions arranged in the claimed spatial relationship relative to the metal plate, optic, reflection sheet, and housing. ¶67 col. 6:58-63
  • Identified Points of Contention:
    • Scope Questions: The interpretation of "light guide member" will be critical. The complaint alleges it reads on an individual optic over an LED. The defense may argue that in the context of the patent, which refers to it as a "light guide panel (LGP)" (’380 Patent, col. 2:36), the term is limited to a larger, continuous sheet designed to diffuse light from edge-mounted LEDs, a different architecture from the direct-lit system in the accused products.
    • Technical Questions: Infringement will require mapping the highly specific three-dimensional arrangement of the "flexible PCB" relative to four other components (metal plate, light guide member, reflection sheet, housing) as claimed. It raises the question of whether the physical construction of the accused TCL backlights precisely matches this complex limitation.

V. Key Claim Terms for Construction

U.S. Patent No. 7,936,415

  • The Term: "closed loop circuit"
  • Context and Importance: This term is the central feature of the asserted claim. Its construction will determine whether a standard serial connection of LED strips, as found in many backlight units, falls within the scope of the patent. Practitioners may focus on this term because it is potentially ambiguous whether it requires a specific feedback path or simply a completed electrical circuit.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The claim language states the loop is formed "by which the connecting terminal... is prepared as a closed loop circuit," which could be argued to encompass any method that terminates a series of modules to complete a circuit (’415 Patent, col. 7:12-14).
    • Evidence for a Narrower Interpretation: The specification's description of FIG. 8 shows a "termination connecting substrate" (145) with specific internal connections (146C, 147C, 148C) that loop signal paths back on themselves (’415 Patent, col. 5:26-42). This specific embodiment could be used to argue that "closed loop circuit" requires more than a simple termination and implies a feedback structure.

U.S. Patent No. 7,922,380

  • The Term: "light guide member"
  • Context and Importance: The viability of the infringement allegation hinges on this term being construed to cover an individual optic over a direct-lit LED. Practitioners may focus on this term because the specification appears to use it interchangeably with "light guide panel (LGP)," which typically refers to a component used in edge-lit, not direct-lit, systems.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The claim itself uses the term "light guide member" without the narrowing word "panel." Plaintiff may argue this term should be given its plain and ordinary meaning of a member that guides light, which an individual optic does.
    • Evidence for a Narrower Interpretation: The specification explicitly states that "The light guide member 120 is a light guide panel (LGP)" (’380 Patent, col. 2:36-37). Furthermore, FIG. 1 depicts the "light guide member" (120) as a large, flat panel characteristic of an edge-lit system, not an array of individual lenses. This intrinsic evidence may strongly support a narrower construction limited to panel-type structures.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges both induced and contributory infringement for all asserted patents. Inducement is based on Defendants allegedly providing products along with "instructions, documentation, technical support, marketing, product manuals, advertisements, and online documentation" that encourage customers to use the products in an infringing manner (e.g., Compl. ¶48, ¶69). Contributory infringement is based on allegations that the accused components are material to the inventions, are not staple articles of commerce, and are known to be especially adapted for use in an infringing manner (e.g., Compl. ¶49, ¶70).
  • Willful Infringement: Willfulness is alleged for all asserted patents. The basis for pre-suit knowledge is the allegation that Defendants have known of the patent portfolio "at least since they were widely publicized during and after LG Innotek's sale to Suzhou Lekin Semiconductor" (e.g., Compl. ¶50, ¶71, ¶85).

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

  • A core issue will be one of definitional scope: can terms rooted in specific patent embodiments, such as "light guide member" (’380 Patent) and "closed loop circuit" (’415 Patent), be construed broadly enough to read on the different technical implementations allegedly used in the accused direct-lit backlight systems? The case may depend heavily on whether the court adopts a broad, plain-meaning interpretation or a narrower one limited by the patents' specifications and drawings.
  • A second central question will be one of evidentiary proof: given the assertion of fourteen distinct patents against a wide array of over a dozen product series, a key challenge for the Plaintiff will be to demonstrate that the specific and often highly detailed technical limitations of each asserted claim are present across the varied architectures of the numerous accused products.
  • Finally, a key legal question will be one of willfulness: can knowledge sufficient for willful infringement be established by the "wide publicizing" of a corporate patent portfolio sale, or will the Plaintiff be required to show more direct evidence that the Defendant was aware of the specific asserted patents and their infringement prior to the lawsuit?