Seoul Semiconductor Co Ltd v. Finelite Inc

I. Executive Summary and Procedural Information

• Case Name: Seoul Semiconductor Co., Ltd. v. Finelite, Inc.
• Parties & Counsel:
  • Plaintiff: Seoul Semiconductor Co., Ltd. (Republic of Korea)
  • Defendant: Finelite, Inc. (California)
  • Plaintiff's Counsel: JONAK LAW GROUP, P.C.
• Case Identification: 3:26-cv-06153, N.D. Cal., 06/22/2026
• Venue Allegations: Venue is alleged to be proper as Defendant Finelite, Inc. is a California corporation that resides in the district, maintains a principal place of business in California, and has allegedly committed acts of infringement within the district.
• Core Dispute: Plaintiff alleges that Defendant's HP-2 WS Luminaire, an LED lighting product, infringes five U.S. patents related to LED device structure, packaging, light emission characteristics, and backlight unit configuration.
• Technical Context: The lawsuit concerns light-emitting diode (LED) technology, which has become dominant in the lighting and display industries due to advantages in energy consumption, lifetime, and form factor.
• Key Procedural History: The complaint details pre-suit communications, including a notification of infringement sent by Plaintiff to Defendant on November 9, 2025, concerning three of the patents-in-suit. Following a denial of infringement by Defendant on January 21, 2026, Plaintiff sent a second notice on June 16, 2026, identifying all five asserted patents and including claim charts, which allegedly went unanswered.

Case Timeline

Date	Event
2011-02-09	U.S. Patent No. 9,112,120 Priority Date
2015-08-18	U.S. Patent No. 9,112,120 Issue Date
2017-08-21	U.S. Patent No. 11,978,837 Priority Date
2018-07-12	U.S. Patent No. 11,876,151 Priority Date
2018-09-14	U.S. Patent No. 12,282,185 Priority Date
2018-09-14	U.S. Patent No. 12,298,552 Priority Date
2024-01-16	U.S. Patent No. 11,876,151 Issue Date
2024-05-07	U.S. Patent No. 11,978,837 Issue Date
2025-04-22	U.S. Patent No. 12,282,185 Issue Date
2025-05-13	U.S. Patent No. 12,298,552 Issue Date
2025-11-09	Plaintiff sends first notice of infringement to Defendant
2026-01-21	Defendant denies infringement allegations
2026-06-16	Plaintiff sends second notice of infringement with claim charts
2026-06-22	Complaint Filing Date

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

U.S. Patent No. 9,112,120

• Patent Identification: U.S. Patent No. 9,112,120, "White Light Source and White Light Source System Including the Same," issued August 18, 2015.
• The Invention Explained:
  • Problem Addressed: The patent's background describes that conventional white LEDs, particularly those using blue LEDs to excite yellow phosphors, have a strong blue light emission peak. This spectral output is significantly different from natural light and may adversely affect human circadian rhythms ʼ120 Patent, col. 1:24-44
  • The Patented Solution: The invention provides a white light source whose emission spectrum is specifically engineered to be close to that of natural light (i.e., black-body radiation) at a given color temperature. This is achieved by designing the light source to satisfy a relational equation that limits the deviation between its spectral output and an ideal black-body radiator's spectrum, when weighted by the human eye's spectral luminous efficiency ʼ120 Patent, abstract ʼ120 Patent, col. 2:45-56
  • Technical Importance: The technology aims to create artificial lighting that more closely mimics the spectral qualities of natural sunlight, which may reduce the negative biological effects associated with prolonged exposure to conventional artificial light sources ʼ120 Patent, col. 2:7-19
• Key Claims at a Glance:
  • The complaint asserts exemplary claim 1 Compl. ¶17
  • The core of independent claim 1 is a white light source that satisfies the relational equation: -0.2≦[(P(λ)×V(λ))/(P(λmax1)×V(λmax1))-(B(λ)×V(λ))/(B(λmax2)×V(λmax2))]≦+0.2, where:
    • P(λ) is the light emission spectrum of the white light source.
    • B(λ) is the light emission spectrum of black-body radiation having the same color temperature as the white light source.
    • V(λ) is the spectrum of a spectral luminous efficiency.
    • λmax1 is the wavelength where P(λ)×V(λ) is largest.
    • λmax2 is the wavelength where B(λ)×V(λ) is largest.
  • The complaint notes infringement of "one or more claims," reserving the right to assert others Compl. ¶17

U.S. Patent No. 11,876,151

• Patent Identification: U.S. Patent No. 11,876,151, "Light emitting device, light emitting diode package, backlight unit, and liquid crystal display," issued January 16, 2024.
• The Invention Explained:
  • Problem Addressed: The patent's background discusses challenges in direct-lighting backlights for liquid crystal displays, including the "spot phenomenon" (uneven brightness above LEDs) and poor contrast during local dimming caused by light leakage from an "on" LED into the zone of an adjacent "off" LED ʼ151 Patent, col. 1:28-54
  • The Patented Solution: The invention proposes an LED package that includes a "dam" structure on the circuit board surrounding the LED chip. The dam is spaced apart from the chip and its geometry (e.g., height, angle, shape) is designed to control the spread of light. This structure helps block light from spilling into adjacent zones, thereby enabling clearer blackouts and improving contrast ratio in displays that use local dimming ʼ151 Patent, abstract ʼ151 Patent, col. 17:28-39
  • Technical Importance: This packaging approach allows for the construction of thinner direct-lit displays with more effective local dimming, which can improve image quality (contrast) and reduce power consumption ʼ151 Patent, col. 1:49-54
• Key Claims at a Glance:
  • The complaint asserts exemplary claim 9 Compl. ¶23
  • Independent claim 9 recites a display apparatus comprising:
    • a circuit board;
    • an optical layer; and
    • at least one light emitter disposed between the board and optical layer, where the emitter itself comprises: a light emitting structure, a light transmitting layer, and a dam.
    • The dam is disposed on the circuit board, surrounds the light emitter, and includes "a portion having a curved shape."
  • The complaint reserves the right to assert additional claims Compl. ¶23

Multi-Patent Capsule: U.S. Patent No. 11,978,837

• Patent Identification: U.S. Patent No. 11,978,837, "Light emitting diode package," issued May 7, 2024.
• Technology Synopsis: This patent describes an LED module unit with a reflective layer disposed on the side of the light emitting structure and an encapsulation portion covering it. This design is intended to reflect light laterally, increasing light extraction efficiency, while a "surface barrier" protects the device from moisture and dust, enhancing reliability '837 Patent, abstract '837 Patent, col. 1:60-67
• Asserted Claims: The complaint asserts exemplary claim 8 Compl. ¶33
• Accused Features: The complaint alleges that the HP-2 WS Luminaire's LED package includes reflective metal layers (including an aluminum layer) under the p-contact that reflect light upwards from the active layer and are both thermally conductive and reflective Compl. ¶¶40-42

Multi-Patent Capsule: U.S. Patent No. 12,282,185

• Patent Identification: U.S. Patent No. 12,282,185, "Backlight unit and display apparatus having the same," issued April 22, 2025.
• Technology Synopsis: This patent discloses a light emitter for a backlight unit that is engineered to have different light profiles and orientation angles in its first and second length directions (e.g., horizontal vs. vertical). This is achieved by using a light blocking layer on a surface of the emitter substrate to control the direction of emitted light, aiming to improve uniformity in slim display apparatuses '185 Patent, abstract '185 Patent, col. 15:15-23
• Asserted Claims: The complaint's Count 4 heading identifies the '185 patent, but the text in paragraph 46 incorrectly references the '837 patent and claim 9. Assuming the count heading is correct, the infringement allegations for this patent focus on claim 9 of the '185 patent.
• Accused Features: The HP-2 WS Luminaire's light emitter is alleged to have a light blocking layer on its second surface and to emit light with a first orientation angle in its horizontal direction that is different from the second orientation angle in its vertical direction Compl. ¶¶50-52

Multi-Patent Capsule: 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 light emitting device for a display apparatus where the substrate includes first and second pad electrodes spaced apart by at least 50 micrometers. The patent also focuses on the emitter's dimensional properties and light profiles, similar to the '185 patent, to achieve a slim backlight with high uniformity '552 Patent, abstract '552 Patent, col. 2:32-36
• Asserted Claims: The complaint asserts exemplary claim 15 Compl. ¶56
• Accused Features: The complaint alleges the HP-2 WS Luminaire's substrate contains pad electrodes with a gap that is greater than 50 micrometers Compl. ¶¶62-63

III. The Accused Instrumentality

• Product Identification: The accused product is the Finelite HP-2 WS Luminaire Compl. ¶17
• Functionality and Market Context: The complaint identifies the HP-2 WS Luminaire as a recessed 2-inch aperture perimeter slot luminaire, marketed as a white light source that provides "efficient, uniform lighting for diverse applications" Compl. ¶18 Compl. p. 6 The complaint's analysis shows the luminaire contains a plurality of LED circuit boards, each populated with multiple light emitters (LED packages) arranged in series Compl. ¶24 Compl. ¶35 The complaint provides a graph from a measurement of the accused product's light output, which allegedly demonstrates its specific spectral characteristics Compl. p. 7 Further allegations are based on physical analysis of the luminaire's components, including scanning electron microscope (SEM) images of the LED chips and packaging Compl. ¶26 Compl. ¶28

IV. Analysis of Infringement Allegations

'120 Patent Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
a white light source satisfying a relational equation of -0.2 ≤ [(P(λ)×V(λ))/(P(λmax1)×V(λmax1)) - (B(λ)×V(λ))/(B(λmax2)×V(λmax2))] ≤ +0.2...	The complaint alleges that the measured light output from the HP-2 WS Luminaire satisfies this relational equation. A graph is provided showing the calculated difference value A(λ) for the accused product across the visible spectrum, with the values falling between -0.2 and +0.2.	¶19	col. 2:45-56

'151 Patent Infringement Allegations

Claim Element (from Independent Claim 9)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
a display apparatus, comprising: a circuit board; ... at least one light emitter ...	The HP-2 WS Luminaire is alleged to be a display apparatus containing a circuit board with at least one light emitter. SEM images show the internal structure of the LED chip.	¶¶24-26	col. 16:41-51
a light transmitting layer ... contacting the light emitter	The accused product allegedly includes a yellow light transmitting layer that covers the surfaces of the light emitter. This is shown in an optical microscope image and an SEM cross-section.	¶28	col. 29:36-39
a dam disposed on the circuit board and surrounding the light emitter and including a portion having a curved shape.	The accused product allegedly has a white dam structure surrounding the yellow light transmitting layer. The complaint asserts this structure is the claimed dam, although no specific curved portion is identified in the provided images.	¶29	col. 16:65-17:2

Identified Points of Contention

• Evidentiary Question ('120 Patent): The core of the '120 patent infringement claim is whether the accused product's light spectrum verifiably meets the precise mathematical formula in claim 1. The complaint presents a graph purporting to show compliance Compl. p. 7 The dispute may focus on the validity and methodology of the plaintiff's measurements versus any counter-measurements presented by the defendant.
• Scope and Technical Question ('151 Patent): A primary issue will be one of claim construction: does the "white dam" structure identified in the accused product's packaging Compl. ¶29 meet the functional and structural definition of the claimed "dam"? The patent specification describes the dam as a feature for controlling light spread to improve local dimming contrast ʼ151 Patent, col. 17:28-39 The analysis may question whether the accused structure performs this specific optical function or is merely a general structural or reflective component.
• Scope Question ('151 Patent): Claim 9 requires the dam to include "a portion having a curved shape." The complaint makes this allegation but does not point to a specific curved feature in its visual evidence Compl. ¶¶28-29 The case may raise the question of whether the accused product's dam, which appears linear in the provided cross-sections, contains any such curved portion.

V. Key Claim Terms for Construction

For the '120 Patent

• The Term: "a same color temperature"
• Context and Importance: The validity of the entire relational equation in claim 1 hinges on comparing the accused product's spectrum P(λ) to a theoretical black-body spectrum B(λ) at the "same color temperature." The allowable tolerance for "same" is not defined. Practitioners may focus on this term because its construction will determine the baseline against which infringement is measured; a narrow definition could render the plaintiff's comparison invalid, while a broad one could make it easier to prove infringement.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The claims and specification do not provide an explicit numerical tolerance for "same," which may support using a standard, potentially flexible, industry definition for correlated color temperature (CCT) ʼ120 Patent, claim 1
  • Evidence for a Narrower Interpretation: The exemplary embodiments calculate the comparison based on specific CCT values (e.g., "5,100 K"), which a party might argue implicitly defines "same" as being numerically identical or extremely close to the measured CCT of the light source ʼ120 Patent, col. 8:37-41

For the '151 Patent

• The Term: "a dam"
• Context and Importance: The infringement theory for the '151 patent relies on construing a physical structure in the accused product as the claimed "dam." The patent specification repeatedly describes the dam's function as restricting light from one LED package from spilling into an adjacent one to enable effective local dimming ʼ151 Patent, col. 17:28-18:14 Whether the accused structure performs this specific light-blocking function or serves a different purpose (e.g., structural support, reflection) will be central to the infringement analysis.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The plain language of claim 9 simply requires "a dam disposed on the circuit board and surrounding the light emitter," which could be read as any wall-like structure in that position ʼ151 Patent, claim 9
  • Evidence for a Narrower Interpretation: The abstract and detailed description heavily emphasize the dam's role in improving contrast by preventing light leakage, suggesting a functional requirement beyond merely being a surrounding structure ʼ151 Patent, abstract ʼ151 Patent, col. 1:45-54 The specification also details specific geometric relationships, such as the angle from the dam to the light emitter being greater than the peak beam angle, which implies a specific optical purpose ʼ151 Patent, col. 18:7-12

VI. Other Allegations

• Willful Infringement: The complaint alleges willful infringement for all five asserted patents. The allegations are based on pre-suit knowledge established through two written notices sent to Finelite. The first notice was sent on November 9, 2025, and the second, which included claim charts for all five patents, was sent on June 16, 2026 (Compl. ¶¶14; Compl. ¶16; Compl. ¶21; Compl. ¶31; Compl. ¶44; Compl. ¶54; Compl. ¶65). The complaint alleges Finelite continued to infringe after receiving these notices.

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

• A core issue will be one of evidentiary proof and methodology: Does the measured light spectrum of the accused HP-2 WS Luminaire, under scientifically valid and repeatable testing conditions, verifiably fall within the precise mathematical boundaries defined by the relational equation in claim 1 of the '120 patent?
• A second central issue will be one of claim construction and function: Can the "white dam" structure identified in the accused product be construed as the claimed "dam," which the '151 patent functionally describes as a light-blocking element for improving local dimming, and does that structure meet the claim's specific geometric requirement of including a "curved shape"?
• A key strategic question will be one of apportionment and overlap: With five distinct patents asserted against a single product-covering its spectral output ('120), physical packaging ('151), reflective layers ('837), light orientation ('185), and electrode spacing ('552)-a significant challenge for the court will be to separately analyze infringement and, if found, apportion damages for each distinct patented technology allegedly embodied in the same device.