DCT

4:26-cv-06154

Seoul Semiconductor Co Ltd v. Planar Systems Inc

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 4:26-cv-06154, S.D. Tex., 07/30/2026
  • Venue Allegations: Plaintiffs allege that venue is proper in the Southern District of Texas because Defendant Planar Systems, Inc. maintains a "regular and established place of business" in the district, specifically a Houston showroom used for marketing, product demonstrations, and sales activities.
  • Core Dispute: Plaintiffs allege that Defendant's VDS Series of LED display products infringe twelve U.S. patents relating to various aspects of LED device structure, fabrication methods, and operational control.
  • Technical Context: The lawsuit concerns the design and manufacture of light-emitting diodes (LEDs) and their integration into high-resolution video displays, a foundational technology in the commercial and consumer electronics markets.
  • Key Procedural History: The complaint details extensive pre-suit correspondence, beginning with a notice letter from Plaintiffs on March 4, 2026, and culminating in a final notice with representative claim charts on July 24, 2026. Plaintiffs allege Defendant failed to cease infringement or meaningfully engage in licensing discussions despite repeated notices, which forms the basis for the willfulness claim. Additionally, U.S. Patent No. 7,667,225 survived an Inter Partes Review (IPR2020-00146), with claims 1, 4-7, 10, 11, and 16-19 confirmed as patentable.

Case Timeline

Date Event
2006-05-18 U.S. Patent No. 7,572,653 Priority Date
2009-08-11 U.S. Patent No. 7,572,653 Issued
2009-08-14 U.S. Patent No. 7,667,225 Priority Date (Filing Date)
2010-02-23 U.S. Patent No. 7,667,225 Issued
2010-09-24 U.S. Patent No. 10,069,048 Priority Date
2012-06-28 U.S. Patent Nos. 9,397,269 & 9,859,469 Priority Date
2013-05-01 U.S. Patent No. 9,520,543 Priority Date
2016-07-19 U.S. Patent No. 9,397,269 Issued
2016-12-13 U.S. Patent No. 9,520,543 Issued
2017-03-13 U.S. Patent No. 12,074,144 Priority Date
2017-09-29 U.S. Patent No. 12,527,133 Priority Date
2018-01-02 U.S. Patent No. 9,859,469 Issued
2018-08-24 U.S. Patent No. 12,156,498 Priority Date
2018-09-04 U.S. Patent No. 10,069,048 Issued
2018-09-14 U.S. Patent No. 12,298,552 Priority Date
2019-03-29 U.S. Patent No. 12,288,838 Priority Date
2019-12-16 IPR (IPR2020-00146) filed against U.S. Patent No. 7,667,225
2020-01-03 U.S. Patent No. 11,961,876 Priority Date
2022-01-31 IPR Certificate Issued for U.S. Patent No. 7,667,225
2024-04-16 U.S. Patent No. 11,961,876 Issued
2024-08-27 U.S. Patent No. 12,074,144 Issued
2024-12-03 U.S. Patent No. 12,156,498 Issued
2025-04-29 U.S. Patent No. 12,288,838 Issued
2025-05-13 U.S. Patent No. 12,298,552 Issued
2026-01-13 U.S. Patent No. 12,527,133 Issued
2026-03-04 Plaintiffs send first notice of infringement to Defendant
2026-03-15 Defendant responds to first notice
2026-04-06 Plaintiffs respond and offer claim charts under NDA
2026-06-03 Plaintiffs send follow-up letter to Defendant
2026-06-04 Defendant responds to follow-up letter
2026-07-24 Plaintiffs send second notice with claim charts for all asserted patents
2026-07-30 Complaint Filed

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

U.S. Patent No. 12,288,838 - "Unit pixel having light emitting device, pixel module and displaying apparatus," Issued April 29, 2025

The Invention Explained

  • Problem Addressed: The patent addresses challenges in manufacturing dense and reliable LED displays, which involve complex fabrication, packaging, and assembly processes that can be costly and time-consuming and may suffer from issues like poor heat dissipation '048 Patent, col. 2:3-14
  • The Patented Solution: The invention describes a specific structural design for a "unit pixel" in an LED display. The core of the solution is a "step adjustment layer" disposed between the circuit board and the light-emitting layer of an LED '838 Patent, abstract This layer covers a region of the emitter but includes a precisely defined "opening region" that creates an electrical contact point between the emitter's connection layer and its semiconductor layer '838 Patent, abstract '838 Patent, col. 28:16-30 This structure provides a defined architecture for mounting and connecting the microscopic LED components within a pixel module.
  • Technical Importance: This architectural approach aims to create a standardized, manufacturable unit pixel structure that can potentially improve the reliability of electrical connections and simplify the assembly process for high-resolution LED displays.

Key Claims at a Glance

  • The complaint asserts at least exemplary claim 1 Compl. ¶43
  • Independent claim 1 of the '838 patent includes the following essential elements:
    • A display apparatus comprising a panel substrate and a pixel module.
    • The pixel module includes a circuit board and a plurality of light emitters.
    • The light emitters are arranged longitudinally along a first direction on the circuit board.
    • Each light emitter comprises a light emitting layer (with first/second conductivity type layers and an active layer), first and second connection layers, and a step adjustment layer.
    • The step adjustment layer is disposed between the circuit board and the light emitting layer, covering a region of it.
    • The step adjustment layer includes an opening region providing an electrical contact between the first connection layer and the first conductivity type semiconductor layer.
    • The plurality of light emitters are also arranged in a second direction crossing the first.
  • The complaint reserves the right to assert additional claims Compl. ¶43

U.S. Patent No. 12,156,498 - "Light source for plant cultivation," Issued December 3, 2024

The Invention Explained

  • Problem Addressed: Conventional light sources for horticulture are primarily designed for photosynthesis and do not provide tailored light spectra to cultivate plants containing a large amount of specific substances beneficial to humans '498 Patent, col. 1:29-43
  • The Patented Solution: The patent describes a "smart" light source that uses a controller to adjust the light spectrum delivered to plants over different time periods. The system employs at least two different light sources (e.g., one for visible light, another for UV light) '498 Patent, abstract '498 Patent, Fig. 1B The controller can operate these sources to create distinct "light recipes," such as a primary growth phase using a standard spectrum and a pre-harvest phase where a different spectrum (e.g., with added UVB light) is applied to increase the content of desired phytochemicals '498 Patent, col. 2:1-9
  • Technical Importance: This technology moves beyond simple plant growth toward "phytochemical farming," using precisely controlled light to enhance the nutritional or medicinal value of cultivated plants.

Key Claims at a Glance

  • The complaint asserts at least exemplary claim 1 Compl. ¶51
  • Independent claim 1 of the '498 patent includes the following essential elements:
    • A light device with a light source module comprising a plurality of light emitters (including first, second, and third emitters with different peak wavelengths).
    • A controller operable to turn on the module.
    • The controller is configured to operate the emitters to provide a "first type of light" with a "first spectral pattern" including a relatively high intensity of the first peak wavelength.
    • The controller is also configured to operate the emitters to provide a "second type of light" with a "second spectral pattern" including a lower intensity of the first peak wavelength.
    • The controller is configured to independently control emission intensity or time.
  • The complaint reserves the right to assert additional claims Compl. ¶51

U.S. Patent No. 11,961,876

  • Patent Identification: U.S. Patent No. 11,961,876, "Light emitting device and LED display apparatus including the same," Issued April 16, 2024.
  • Technology Synopsis: The patent describes an LED display apparatus where individual light-emitting units (e.g., red, green, blue) are arranged horizontally, side-by-side, rather than stacked vertically '876 Patent, abstract This arrangement aims to prevent light from one emitter from being absorbed by another, a problem in stacked designs, and allows for more flexible sequencing of the LED units '876 Patent, col. 5:5-14
  • Asserted Claims: At least exemplary claim 1 Compl. ¶61
  • Accused Features: The accused product's display substrate, its arrangement of pixels in a matrix, and the side-by-side disposition of the three emitters within each pixel Compl. ¶¶62-63

U.S. Patent No. 12,074,144

  • Patent Identification: U.S. Patent No. 12,074,144, "Display device," Issued August 27, 2024.
  • Technology Synopsis: This patent focuses on the specific geometry of substrate electrodes used to connect to light sources in a display. It claims an electrode structure with a "substantially flat" upper and lower side, where the width of the substrate electrode is greater than the width of the p-type or n-type electrode on the light source to which it connects '144 Patent, abstract '144 Patent, claim 1 This design may improve the reliability of the electrical connection.
  • Asserted Claims: At least exemplary claim 15 Compl. ¶70
  • Accused Features: The accused product's substrate electrodes, which allegedly have flat upper and lower sides and are wider than the light source electrodes they connect to Compl. ¶¶73-76

U.S. Patent No. 12,527,133

  • Patent Identification: U.S. Patent No. 12,527,133, "Light emitting device and display apparatus including the same," Issued January 13, 2026.
  • Technology Synopsis: The invention discloses a display device featuring a "partition layer" with a specific height range disposed between light emitters '133 Patent, abstract This opaque layer is designed to prevent optical crosstalk between adjacent sub-pixels, thereby improving color purity. The patent also claims specific dimensional relationships between the emitters and the openings in the partition layer.
  • Asserted Claims: At least exemplary claim 10 Compl. ¶81
  • Accused Features: The accused product's use of a partition layer with openings for the LEDs, where the layer allegedly meets the claimed height and dimensional characteristics Compl. ¶¶85-90

U.S. Patent No. 12,298,552

  • Patent Identification: U.S. Patent No. 12,298,552, "Backlight unit and display apparatus having the same," Issued May 13, 2025.
  • Technology Synopsis: This patent describes a backlight unit with a specific geometric relationship between the light emitter and its electrical connection points. It claims a structure where the gap between the first and second pad electrodes is different from the length of the emitter and is greater than about 50 micrometers '552 Patent, abstract '552 Patent, claim 15 This configuration may relate to electrical isolation and manufacturing tolerances.
  • Asserted Claims: At least exemplary claim 15 Compl. ¶94
  • Accused Features: The accused product's light emitters, pad electrodes, and the alleged gap between the electrodes, which is claimed to be greater than 50 micrometers Compl. ¶¶96-97

U.S. Patent No. 10,069,048

  • Patent Identification: U.S. Patent No. 10,069,048, "Wafer-level light emitting diode package and method of fabricating the same," Issued September 4, 2018.
  • Technology Synopsis: The patent discloses a "wafer-level" LED package designed for miniaturization and protection from the environment. The invention includes a semiconductor stack with defined sidewalls, along with inner and outer insulation layers formed over the stack to protect it '048 Patent, claim 1 '048 Patent, claim 17 This encapsulation at the wafer level aims to improve durability and streamline manufacturing.
  • Asserted Claims: At least exemplary claim 1 Compl. ¶101
  • Accused Features: The accused product's LED package, which is alleged to include the claimed semiconductor stack, external sidewalls, and protective inner and outer insulation layers Compl. ¶¶102-105

U.S. Patent No. 9,520,543

  • Patent Identification: U.S. Patent No. 9,520,543, "Light-emitting diode module having light-emitting diode joined through solder paste and light-emitting diode," Issued December 13, 2016.
  • Technology Synopsis: This patent details an LED module where diodes are bonded to a printed circuit board using solder paste. A key feature is the inclusion of an "anti-diffusion reinforcing layer" placed on the reflective electrode structure of the diode, to which an electrode pad is connected '543 Patent, abstract This layer is intended to prevent materials from diffusing during the soldering process, which could degrade performance.
  • Asserted Claims: At least exemplary claim 1 Compl. ¶109
  • Accused Features: The accused product's use of solder paste to bond LEDs to a circuit board, and the alleged presence of a reflective electrode structure with an anti-diffusion reinforcing layer Compl. ¶¶110-112

U.S. Patent No. 7,667,225

  • Patent Identification: U.S. Patent No. 7,667,225, "Light emitting device," Issued February 23, 2010.
  • Technology Synopsis: The invention relates to improving the efficiency of LEDs by creating "carrier trap portions" within the multi-quantum well (MQW) active layer '225 Patent, abstract This is achieved by varying the concentration of indium, creating regions with a lower band-gap energy that "trap" charge carriers (electrons and holes), increasing the probability of their recombination to produce light.
  • Asserted Claims: At least exemplary claim 1 Compl. ¶105
  • Accused Features: The accused product's LEDs are alleged to have a multi-quantum well structure that includes indium, with varying concentrations creating the claimed carrier trap portions Compl. ¶¶107-108

U.S. Patent No. 7,572,653

  • Patent Identification: U.S. Patent No. 7,572,653, "Method of fabricating light emitting diode," Issued August 11, 2009.
  • Technology Synopsis: This patent claims a method for fabricating an LED with an inclined sidewall to improve light extraction efficiency. The method involves using a photoresist pattern with a sloped sidewall as an etching mask, which transfers the sloped profile to the semiconductor layers during the etching process '653 Patent, abstract A vertical sidewall can trap light due to total internal reflection.
  • Asserted Claims: At least exemplary claim 1 Compl. ¶112
  • Accused Features: The complaint alleges infringement under 35 U.S.C. § 271(g) by importing a product made by the patented process, citing the angled nature of the LED's mesa as evidence that the method was used Compl. ¶116

U.S. Patent No. 9,859,469

  • Patent Identification: U.S. Patent No. 9,859,469, "Light emitting diode for surface mount technology, method of manufacturing the same, and method of manufacturing light emitting diode module," Issued January 2, 2018.
  • Technology Synopsis: The invention describes an LED structure with a specific insulating layer design. The insulating layer has a first region with a varying thickness and a second region with a substantially constant thickness '469 Patent, abstract This differential thickness may be used to manage electrical fields or optical properties in a targeted way.
  • Asserted Claims: At least exemplary claim 1 Compl. ¶120
  • Accused Features: The accused product's insulating layer, which is alleged to have a region of varying thickness and another region of constant thickness Compl. ¶122

U.S. Patent No. 9,397,269

  • Patent Identification: U.S. Patent No. 9,397,269, "Light emitting diode for surface mount technology, method of manufacturing the same, and method of manufacturing light emitting diode module," Issued July 19, 2016.
  • Technology Synopsis: This patent discloses an LED with a "reflection pattern" designed to manage light and mechanical stress. The pattern includes a conductive barrier layer, a reflective metal layer, and a "stress relaxation layer" configured to absorb stress caused by different coefficients of thermal expansion between the other layers '269 Patent, abstract '269 Patent, col. 2:48-56
  • Asserted Claims: At least exemplary claim 1 Compl. ¶126
  • Accused Features: The accused product's reflection pattern, which is alleged to contain the claimed conductive barrier layer, reflective metal layer, and stress relaxation layer Compl. ¶¶128-129

III. The Accused Instrumentality

Product Identification

  • Planar Leyard VDS Series 993-3887-00 Compl. ¶43

Functionality and Market Context

  • The accused product is an indoor LED video wall display Compl. ¶45 The complaint alleges it utilizes Chip-on-Board (COB) technology, where LED chips are directly mounted on a circuit board, and features a "fully-encapsulated" design that makes the displays resistant to collision, scratches, and dust Compl. ¶45
  • The complaint presents several images to illustrate the product's construction. A photograph of the product shows a modular display unit Compl. ¶44 A screenshot from Planar's website describes the VDS Series as delivering "beautiful, high-resolution visualization with fine pixel pitches" Compl. ¶45 Further technical evidence is provided through optical and scanning electron microscope (SEM) images, which purport to show the internal structure of the product's pixel modules and individual light emitters Compl. ¶46 Compl. ¶47

IV. Analysis of Infringement Allegations

'838 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
a display apparatus, comprising: a panel substrate; and a pixel module disposed on the panel substrate... The accused Planar product is a display apparatus that includes a panel substrate and a pixel module disposed on it. ¶44 col. 28:16-19
the pixel module including: a circuit board; and a plurality of light emitters longitudinally extending along a first direction and disposed on the circuit board... The pixel module includes a circuit board with a plurality of light emitters arranged along a first direction. A cross-sectional microscope image is provided as evidence. ¶46 col. 28:20-22
each light emitter of the plurality of light emitters comprising: a light emitting layer including a first conductivity type semiconductor layer, a second conductivity type semiconductor layer, and an active layer... The light emitters contain a light emitting layer with first and second conductivity type semiconductor layers and an interposed active layer, as shown in SEM images. ¶47 col. 28:24-27
a first connection layer electrically connected to the first conductivity type semiconductor layer; a second connection layer electrically connected to the second conductivity type semiconductor layer; and... The light emitters include first and second connection layers electrically connected to their respective semiconductor layers. ¶47 col. 28:27-30
a step adjustment layer disposed between the circuit board and the light emitting layer and covering a region of the light emitting layer... A step adjustment layer is allegedly disposed between the circuit board and the light emitting layer, covering a portion of it. This is supported by SEM images. ¶47 col. 28:30-32
the step adjustment layer includes an opening region that provides an electrical contact region between the first connection layer and the first conductivity type semiconductor layer. The step adjustment layer includes an opening that creates an electrical contact region between the connection layer and the semiconductor layer. ¶47 col. 28:33-36
wherein the plurality of light emitters in the pixel module are arranged and aligned in a second direction crossing the first direction. The light emitters are arranged in a second direction that crosses the first, as shown in an optical microscope image of the pixel module's top view. ¶46 col. 28:37-39

'498 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
A light device, comprising: a light source module configured to emit light, the light source module including: a plurality of light emitters... The accused Planar product is a light device with a light source module that emits light and includes a plurality of light emitters (red, green, and blue LEDs). ¶52; ¶53 col. 24:8-10
a first light emitter having a first active layer emitting light having a first peak wavelength within a first color wavelength band range... The product includes a first light emitter (e.g., a red LED) with an active layer emitting a first peak wavelength, as shown in FIB-SEM images. ¶54 col. 24:11-13
a second light emitter having a second active layer emitting light having a second peak wavelength within a second wavelength band range... The product includes a second light emitter (e.g., a blue LED) with an active layer emitting a second peak wavelength. ¶54 col. 24:13-15
a third light emitter having a third active layer emitting light having a third peak wavelength different from the second peak wavelength... The product includes a third light emitter (e.g., a green LED) with an active layer emitting a third peak wavelength. ¶54 col. 24:16-18
a controller operable to turn on the light source module... The product includes a controller, shown in photographs of the product's internal circuitry, which operates the light source module. ¶57 col. 24:20-21
wherein the controller is configured to operate at least one of the first, second, or third light emitters to provide a first type of light having a first spectral pattern including a relatively high intensity of the first peak wavelength... The controller is allegedly configured to operate the emitters to produce a first type of light with a first spectral pattern, shown in a photograph of the display emitting a first color. ¶55; ¶57 col. 24:22-26
wherein the controller is configured to operate at least one of the first, second, or third light emitters to provide a second type of light having a second spectral pattern including a lower intensity of the first peak wavelength... The controller is allegedly configured to operate the emitters to produce a second type of light with a second spectral pattern, shown in a photograph of the display emitting a second color. ¶55; ¶57 col. 24:26-30
wherein the controller is configured to independently control an emission intensity or an emission time of light emitted from at least one of the first, second, or third light emitters. The controller is allegedly configured to independently control the emission intensity or time of the light emitters. ¶57 col. 24:31-34
  • Identified Points of Contention:
    • Structural Equivalence ('838 Patent): A central dispute may be whether the layers identified by Plaintiffs in the accused product via SEM imagery Compl. ¶47 perform the functions of and meet the structural limitations of the claimed "step adjustment layer" and its "opening region." The defense may argue that the observed structures are merely conventional encapsulation or bonding layers that are structurally and functionally distinct from the specific architecture claimed in the '838 patent.
    • Operational Capability ('498 Patent): The complaint alleges the accused product's controller is "configured to" perform the claimed light--control method Compl. ¶57 The infringement analysis may turn on whether the mere presence of a controller and different colored LEDs is sufficient to prove this "configured to" limitation, or if Plaintiffs must provide more direct evidence, such as an analysis of the controller's firmware or operational modes, to demonstrate it is capable of generating the different "spectral patterns" as claimed.

V. Key Claim Terms for Construction

  • '838 Patent

    • The Term: "step adjustment layer"
    • Context and Importance: This term is not a standard term of art and appears to be a neologism specific to the patent. Its definition is crucial because infringement hinges on whether a specific layer in the accused product Compl. ¶47 can be characterized as this claimed element. Practitioners may focus on this term because its construction will likely determine whether a key structural element of the claim reads on the accused device.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The specification describes the layer's function as being "disposed between the circuit board and the light emitting layer and covering a region of the light emitting layer" '838 Patent, abstract This functional description could support an argument that any layer in that position performing a spacing or partial covering function meets the definition.
      • Evidence for a Narrower Interpretation: The claim requires the layer to include an "opening region that provides an electrical contact region" '838 Patent, claim 1 The specific embodiments shown in the patent's figures '838 Patent, Figs. 2A-2B illustrate a distinct, patterned layer. This may support a narrower construction requiring a specifically manufactured shape, not just an incidental gap in an encapsulation layer.

  • '498 Patent

    • The Term: "a second spectral pattern including a lower intensity of the first peak wavelength"
    • Context and Importance: This term defines the required change in the light output controlled by the invention. The infringement question will depend on what type and magnitude of spectral change satisfy this limitation. The complaint shows photographs of the display emitting two different colors as evidence Compl. ¶55, but the key question is whether this visual change corresponds to the specific spectral change claimed.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The claim language is relatively open, requiring only a "lower intensity" of the "first peak wavelength." This could be argued to cover any operational mode that, for example, reduces the power to the first LED while activating others, thereby changing the overall color and lowering the relative intensity of the first LED's peak.
      • Evidence for a Narrower Interpretation: The patent's purpose is tied to plant cultivation and generating specific biological responses '498 Patent, col. 1:29-43 This context may support a narrower construction where the "second spectral pattern" must be a specific, horticulturally significant recipe (e.g., adding UVB light, as described in the specification ('498 Patent, col. 2:33-40)), not just any arbitrary color change that the display can produce.

VI. Other Allegations

  • Indirect Infringement: The complaint does not contain explicit counts for indirect infringement (inducement or contributory infringement), focusing instead on direct infringement under 35 U.S.C. § 271(a) and infringement via importation of a product made by a patented process under § 271(g) Compl. ¶112
  • Willful Infringement: The complaint alleges willful infringement for all asserted patents Compl. ¶49 Compl. ¶59 The basis for this allegation is a detailed history of pre-suit communications, starting with a March 4, 2026 notice letter Compl. ¶33 Plaintiffs allege that despite multiple notices, offers to provide claim charts under an NDA, and the eventual provision of claim charts, Defendant "continued to make, use, offer for sale, sell, and/or import products that infringe" Compl. ¶39 This alleged deliberate continuation of infringing activity after acquiring actual knowledge of the patents and infringement allegations forms the core of the willfulness claim.

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

  • Structural vs. Functional Interpretation: A primary issue will be one of claim scope and interpretation across multiple patents. Does the micro-architecture of the accused LEDs, as revealed in Plaintiffs' SEM images, embody the specific, narrowly-defined structures like the '838 patent's "step adjustment layer" or the '269 patent's "stress relaxation layer"? Or, will the court find these to be different structures that achieve a similar function, potentially leading to a dispute over literal infringement versus the doctrine of equivalents?
  • Evidentiary Sufficiency for "Configured To" Claims: For functional patents like the '498 patent, a key question will be one of evidentiary proof: does showing that a product contains a controller and hardware capable of performing a claimed function Compl. ¶57 suffice to prove it is "configured to" infringe, or must Plaintiffs demonstrate that the product's software or operational modes actually implement the claimed multi-period, spectral-shifting methods for plant growth?
  • Proof of Patented Process: A central question for the '653 method patent will be one of circumstantial evidence: can the observation of a physical characteristic in the final product-the angled nature of an LED's mesa Compl. ¶116-be sufficient to prove, by a preponderance of the evidence, that the product was manufactured using the specific multi-step etching process claimed in the patent, thereby establishing infringement under 35 U.S.C. § 271(g)?
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