DCT

1:25-cv-00444

Seoul Semiconductor Co Ltd v. Hawthorne Gardening Co

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:25-cv-00444, D. Del., 04/09/2025
  • Venue Allegations: Venue is alleged to be proper as Defendant is a Delaware corporation that resides in the district and has committed alleged acts of infringement within the district.
  • Core Dispute: Plaintiffs allege that Defendant’s Gavita series of horticulture lighting products infringe eleven patents related to a wide range of LED technologies, including light spectrum characteristics, color rendering, and semiconductor device structures.
  • Technical Context: The patents-in-suit concern foundational aspects of light-emitting diode (LED) technology, which is a critical component in the modern lighting industry, particularly for specialized and high-value applications such as indoor horticulture.
  • Key Procedural History: The complaint alleges that between November 2024 and March 2025, Plaintiffs sent Defendant and its parent company, Scotts Miracle-Gro, a series of warning letters identifying specific patents and accused products, and included claim charts demonstrating the alleged infringement. Plaintiffs allege that Defendant failed to provide a substantive response or cease the accused activities, which forms the basis for the willfulness allegations. One of the asserted patents, U.S. Patent No. 7,667,225, was subject to an Inter Partes Review (IPR2020-00146) which concluded with a certificate confirming the patentability of asserted exemplary claim 1, among others.

Case Timeline

Date Event
2005-08-29 U.S. Patent No. 7,397,069 Priority Date
2008-07-08 U.S. Patent No. 7,397,069 Issued
2009-08-14 U.S. Patent No. 7,667,225 Priority Date
2010-01-05 U.S. Patent No. 10,418,514 Priority Date
2010-02-23 U.S. Patent No. 7,667,225 Issued
2011-02-09 U.S. Patent No. 9,112,120 Priority Date
2011-09-01 U.S. Patent No. 8,981,410 Priority Date
2013-09-24 U.S. Patent No. 9,269,868 Priority Date
2015-03-17 U.S. Patent No. 8,981,410 Issued
2015-08-18 U.S. Patent No. 9,112,120 Issued
2016-02-23 U.S. Patent No. 9,269,868 Issued
2016-02-23 U.S. Patent No. 9,269,871 Issued
2017-07-25 U.S. Patent No. 9,716,210 Issued
2018-02-23 U.S. Patent No. 12,218,290 Priority Date
2018-08-10 U.S. Patent No. 12,078,302 Priority Date
2019-05-20 U.S. Patent No. 11,622,509 Priority Date
2019-09-17 U.S. Patent No. 10,418,514 Issued
2019-12-16 Inter Partes Review IPR2020-00146 Filed for ’225 Patent
2022-01-31 U.S. Patent No. 7,667,225 IPR Certificate Issued
2023-04-11 U.S. Patent No. 11,622,509 Issued
2024-09-03 U.S. Patent No. 12,078,302 Issued
2024-11-11 Plaintiff sends first warning letter to Defendant (Compl. ¶21)
2024-12-11 Plaintiff sends second warning letter to Defendant (Compl. ¶22)
2024-12-20 Defendant’s counsel acknowledges receipt of letters (Compl. ¶23)
2025-01-06 Plaintiff sends third warning letter to Defendant (Compl. ¶24)
2025-02-04 U.S. Patent No. 12,218,290 Issued
2025-03-24 Plaintiff sends fourth warning letter to Defendant (Compl. ¶25)
2025-04-09 Complaint Filing Date

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

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 background describes concerns that conventional white light sources using LEDs have light emission spectra significantly different from natural light, which may adversely affect human circadian rhythms after long-term exposure (Compl. Ex. A, ’120 Patent, col. 1:47-52).
  • The Patented Solution: The invention provides a white light source whose emission spectrum, when weighted by the standard spectral luminous efficiency of the human eye, is mathematically close to the spectrum of black-body radiation (like natural sunlight) at the same color temperature. This is achieved by defining a specific relational equation that the light source must satisfy, ensuring its perceived light spectrum closely mimics that of a natural light source (’120 Patent, col. 2:45-56, Abstract).
  • Technical Importance: This approach sought to create artificial lighting that is more "natural" and potentially healthier for humans by reducing the spectral distortions common in early-generation white LEDs (’120 Patent, col. 2:36-41).

Key Claims at a Glance

  • The complaint asserts at least exemplary independent claim 1 (Compl. ¶29).
  • Essential elements of claim 1 include:
    • A white light source satisfying 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
    • where B(λ) is the light emission spectrum of black-body radiation having a same color temperature as the white light source
    • where V(λ) is a spectrum of a spectral luminous efficiency
    • where λmax1 is a wavelength at which P(λ)×V(λ) is largest
    • where λmax2 is a wavelength at which B(λ)×V(λ) is largest

U.S. Patent No. 11,622,509 - “Light Source for Plant Cultivation,” Issued April 11, 2023

The Invention Explained

  • Problem Addressed: The patent notes that conventional light sources used for plant cultivation, including early LEDs, do not adequately provide light in the specific wavelength bands necessary for efficient photosynthesis, or they consume excessive energy and cost (Compl. Ex. B, ’509 Patent, col. 1:21-37).
  • The Patented Solution: The invention proposes a light source for plant cultivation that combines at least two distinct types of light sources. A "first light source" produces white light with a primary peak (e.g., blue) and a broad sub-peak (e.g., green-to-red). A "second light source" adds a targeted peak in a different part of the spectrum. This combination creates a mixed light spectrum designed to maximize the overlap with the "McCree curve," which defines the optimal spectrum for photosynthesis, thereby increasing light efficiency for plant growth (’509 Patent, Abstract; col. 2:20-29).
  • Technical Importance: The invention provides a method for spectrally tuning LED light sources to more closely match the photosynthetic needs of plants, potentially leading to more efficient and cost-effective indoor farming (’509 Patent, col. 2:20-29).

Key Claims at a Glance

  • The complaint asserts at least exemplary independent claim 10 (Compl. ¶34).
  • Essential elements of claim 10 include:
    • A device comprising first light sources and second light sources disposed on a substrate.
    • The number of second light sources is different from the number of first light sources.
    • Each first light source emits a first light having a first peak at a wavelength from about 400 nm to about 500 nm.
    • The first light also has a first sub-peak with a full-width at half-maximum greater than that of the first peak.
    • Each second light source emits a second light having a second peak at a wavelength from about 500 nm to about 700 nm.
    • The second peak has an intensity greater than an intensity of the first sub-peak of the first light.

Multi-Patent Capsule: U.S. Patent No. 12,078,302

  • Patent Identification: U.S. Patent No. 12,078,302, “Light Source for Plant Cultivation and Plant Cultivation Device,” Issued September 3, 2024.
  • Technology Synopsis: This patent describes a light source for plant cultivation where a "first light source" emits light having a spectrum that overlaps with a normalized solar spectrum by at least about 55% and has a peak deviation no greater than about 0.14 compared to the solar spectrum (Compl. ¶41; Compl. Ex. C, '302 Patent, Abstract). The goal is to create an artificial light source that closely mimics natural sunlight to optimize plant growth.
  • Asserted Claims: Exemplary claim 11 (Compl. ¶40).
  • Accused Features: The complaint alleges the Gavita product contains a first light source whose spectrum meets the claimed overlap and deviation parameters relative to a normalized solar spectrum, and also includes second and third light sources (Compl. ¶41-42).

Multi-Patent Capsule: U.S. Patent No. 12,218,290

  • Patent Identification: U.S. Patent No. 12,218,290, “LED Lighting Apparatus Having Improved Color Rendering and LED Filament,” Issued February 4, 2025.
  • Technology Synopsis: The patent addresses improved color rendering in LED lighting. It describes a light source combining a blue emitter with specific yellow and red phosphors, where the phosphors are characterized by different emission peaks and different full widths at half maximum (FWHM), with the yellow phosphor's FWHM being longer than the red phosphor's (Compl. ¶47-48; Compl. Ex. D, '290 Patent, Abstract).
  • Asserted Claims: Exemplary claim 14 (Compl. ¶46).
  • Accused Features: The complaint accuses the Gavita product's light source of containing a blue emitter, a yellow phosphor, and a red phosphor that meet the claimed emission peak ranges and relative FWHM characteristics (Compl. ¶47-48).

Multi-Patent Capsule: U.S. Patent No. 7,397,069

  • Patent Identification: U.S. Patent No. 7,397,069, “Semiconductor Device,” Issued July 8, 2008.
  • Technology Synopsis: This patent relates to the micro-architecture of a semiconductor device. It describes a specific layered structure including an "impurity diffusion prevention layer" with a high indium concentration and an "overflow prevention layer" with a low indium concentration, which creates a band gap profile designed to prevent impurity diffusion and carrier overflow within the device (Compl. ¶54; Compl. Ex. E, '069 Patent, Abstract).
  • Asserted Claims: Exemplary claim 1 (Compl. ¶52).
  • Accused Features: The complaint alleges the LED chips in the Gavita product contain the specific multi-layer epitaxial structure claimed, including the impurity diffusion and overflow prevention layers with their respective indium concentrations (Compl. ¶54).

Multi-Patent Capsule: U.S. Patent No. 9,269,868

  • Patent Identification: U.S. Patent No. 9,269,868, “Semiconductor Light Emitting Element and Method For Manufacturing Semiconductor Light Emitting Element,” Issued February 23, 2016.
  • Technology Synopsis: The patent describes a semiconductor light emitting element with a layered structure designed to improve performance. It specifies a structure with first, second, and third layers between a first well layer and a p-type semiconductor layer, each having different concentrations of a magnesium (Mg) dopant (Compl. ¶60; Compl. Ex. F, '868 Patent, Abstract).
  • Asserted Claims: Exemplary claim 1 (Compl. ¶58).
  • Accused Features: The LED chips in the accused product are alleged to have the claimed three-layer structure with varying levels of magnesium doping between the p-type layer and the first well layer (Compl. ¶60).

Multi-Patent Capsule: 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: This patent details a light emitting device with a multi-quantum well structure. The invention is a "carrier trap portion" within at least one well layer, characterized by a band-gap energy that gradually decreases from the periphery of the trap portion to its center, which is intended to improve device efficiency (Compl. ¶69; Compl. Ex. G, '225 Patent, Abstract).
  • Asserted Claims: Exemplary claim 1 (Compl. ¶64).
  • Accused Features: The complaint alleges, based on atomic probe tomography, that the LED chips in the Gavita product have well layers with an increasing indium concentration from periphery to center, which allegedly creates the claimed decreasing band-gap energy profile of a carrier trap portion (Compl. ¶68-69).

Multi-Patent Capsule: U.S. Patent No. 9,716,210

  • Patent Identification: U.S. Patent No. 9,716,210, “Light Emitting Diode and Method of Fabricating the Same,” Issued July 25, 2017.
  • Technology Synopsis: This patent describes an LED structure with a "spacer layer" and a "superlattice layer" disposed between the n-type contact layer and the active region. The invention relates to the relative bandgaps of these layers compared to the quantum well and barrier layers of the active region, aiming to improve device characteristics (Compl. ¶75-76; Compl. Ex. H, '210 Patent, Abstract).
  • Asserted Claims: Exemplary claim 1 (Compl. ¶73).
  • Accused Features: Based on TEM images, the complaint alleges the LED chips in the accused product contain the claimed superlattice and spacer layers, and that these layers have the required relative bandgap energies (Compl. ¶75-76).

Multi-Patent Capsule: U.S. Patent No. 10,418,514

  • Patent Identification: U.S. Patent No. 10,418,514, “Light Emitting Diode and Method of Fabricating the Same,” Issued September 17, 2019.
  • Technology Synopsis: This patent is similar to the ’210 patent, describing an LED structure with a "spacer layer" and a "superlattice layer" situated between the n-type contact layer and the active region. The invention focuses on the relative bandgaps of these layers to improve performance, specifying that the spacer layer has a bandgap smaller than the barrier layers but higher than the quantum well layers (Compl. ¶82-83; Compl. Ex. I, '514 Patent, Abstract).
  • Asserted Claims: Exemplary claim 1 (Compl. ¶80).
  • Accused Features: The complaint alleges the LED chips in the Gavita product possess the claimed spacer and superlattice layer structure with the required relative bandgap properties (Compl. ¶82-83).

Multi-Patent Capsule: U.S. Patent No. 8,981,410

  • Patent Identification: U.S. Patent No. 8,981,410, “Distributed Bragg Reflector for Reflecting Light of Multiple Wavelengths from an LED,” Issued March 17, 2015.
  • Technology Synopsis: The patent describes a reflector structure on the backside of an LED substrate. The invention is a Distributed Bragg Reflector (DBR) with at least two pluralities of periods, where the layers in each plurality have different thicknesses, designed to efficiently reflect light of multiple wavelengths (e.g., both blue and yellow) back through the LED (Compl. ¶91; Compl. Ex. J, '410 Patent, Abstract).
  • Asserted Claims: Exemplary claim 1 (Compl. ¶87).
  • Accused Features: SEM images are used to allege that the Gavita product's LEDs include a DBR on the back of the substrate with two distinct pluralities of periods, each comprising interleaved layers of different materials and thicknesses (Compl. ¶90-91).

Multi-Patent Capsule: U.S. Patent No. 9,269,871

  • Patent Identification: U.S. Patent No. 9,269,871, “Light Emitting Diode,” Issued February 23, 2016.
  • Technology Synopsis: This patent details the electrode structure on an LED chip. The invention includes a "first electrode structure" with an electrode pad and an extension portion, and a "current shielding layer" formed underneath the electrode structure to improve current spreading and light extraction (Compl. ¶98-100; Compl. Ex. K, '871 Patent, Abstract).
  • Asserted Claims: Exemplary claim 1 (Compl. ¶95).
  • Accused Features: The complaint alleges the LED chips in the Gavita product have the claimed electrode structure, including a pad-type current shielding layer under the electrode pad and a dot-pattern current shielding layer under the extension portion (Compl. ¶99-100).

III. The Accused Instrumentality

Product Identification

  • The complaint names several horticulture lighting products, with a focus on the HGC906409 Gavita Pro RS 2400e LED light fixture ("Gavita product"). Other accused products include the Gavita RS 1900e LED, Gavita CT 1930e LED, Gavita CT 2000e LED, Gavita Pro 1700e LED, Gavita Pro 1650e, Gavita Pro 900e, and Gavita LED Clone Bar series (Compl. ¶6, 29).

Functionality and Market Context

  • The accused products are LED-based light fixtures designed and sold for horticulture applications (Compl. ¶6). The complaint alleges these products incorporate a range of advanced LED technologies, from specific light spectra tailored for plant growth to complex semiconductor device architectures and electrode designs, allegedly covered by the patents-in-suit (Compl. ¶30, 35, 41, 47, 54, 60, 68, 75, 82, 90, 97). A photograph provided in the complaint shows an array of LEDs mounted on a substrate, including visibly distinct "first light source" and "second light source" packages (Compl. p. 11, ¶35).

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 the relational equation: −0.2 ≤ [(P(λ)×V(λ))/(P(λmax1)×V(λmax1))−(B(λ)×V(λ))/(B(λmax2)×V(λmax2))] ≤ +0.2... The Gavita product is a white light source whose light emission spectrum, when calculated according to the relational equation, produces values between -0.2 and +0.2 across the relevant wavelengths. The complaint includes a graph plotting the result of this equation for the Gavita product. ¶30 col. 22:10-23
  • Identified Points of Contention:
    • Factual Question: The primary dispute will be factual, centering on whether spectral measurements of the accused product, when plugged into the claimed equation, consistently yield results within the claimed range of -0.2 to +0.2. This will likely involve a battle of expert testing and analysis.
    • Scope Questions: A potential issue is the precise definition of "a same color temperature." The method of determining this temperature for both the accused product and the reference black-body radiation could become a point of contention affecting the outcome of the relational equation.

’509 Patent Infringement Allegations

Claim Element (from Independent Claim 10) Alleged Infringing Functionality Complaint Citation Patent Citation
A device for providing light, comprising: first light sources disposed on a substrate... and second light sources disposed on the substrate... The Gavita product includes two visibly distinct types of LED packages mounted on a substrate, identified as a "first light source" and a "second light source." ¶35 col. 13:31-33
wherein a number of the second light sources is different from the number of the first light sources... The accused product allegedly has a different number of "second light sources" than "first light sources," as depicted in an image of the light fixture. ¶35 col. 14:1-3
each first light source configured to emit... a first light having a first peak at a wavelength from about 400 nm to about 500 nm and a first sub-peak having a full-width at half-maximum greater than a full-width at half-maximum of the first peak... The "first light source" LEDs allegedly emit light with a spectrum matching these peak and sub-peak characteristics, as shown in a spectral graph. ¶36 col. 13:34-40
each second light source configured to emit... a second light having a second peak at a wavelength from about 500 nm to about 700 nm, the second peak having an intensity greater than an intensity of the first sub-peak of the first light... The "second light source" LEDs allegedly emit light with a spectrum matching these peak and intensity characteristics, as shown in a spectral graph. A graph in the complaint shows the "second light source" spectrum (in red) and the "first light source" spectrum (in black). ¶36 col. 13:41-47
  • Identified Points of Contention:
    • Scope Questions: A key question for claim construction may be the definition of a "light source." Defendant may argue that the collection of different LED packages on a single board constitutes a single, integrated light source, not the plurality of distinct "first light sources" and "second light sources" required by the claim.
    • Technical Questions: The analysis will turn on whether the measured spectra of the distinct LED packages on the accused product fall within the claimed wavelength ranges and meet the relative intensity and FWHM requirements.

V. Key Claim Terms for Construction

For the ’120 Patent:

  • The Term: "a same color temperature"
  • Context and Importance: The validity of the entire infringement allegation for the '120 patent hinges on comparing the accused product's spectrum to a black-body radiation spectrum at the "same color temperature." Practitioners may focus on this term because any ambiguity in how "same" is measured or defined (e.g., tolerance level, measurement conditions) could alter the outcome of the relational equation central to claim 1.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification's general discussion of creating light similar to "natural light" could support an argument that "same" does not require absolute mathematical identity but rather a functional similarity recognized in the field of lighting science (’120 Patent, col. 1:47-52).
    • Evidence for a Narrower Interpretation: The patent's reliance on a precise mathematical formula suggests that its inputs, including color temperature, should also be determined with a high degree of precision. The claim language itself, lacking any qualifier like "substantially" or "approximately," may support a narrower, more literal interpretation.

For the ’509 Patent:

  • The Term: "first light sources" and "second light sources"
  • Context and Importance: Claim 10 requires the presence of physically distinct pluralities of "first light sources" and "second light sources" that also differ in number. Practitioners may focus on this term because the defendant could argue that its product, which integrates different LED emitters onto a single circuit board, constitutes a single, composite "light source," thereby avoiding infringement of a claim requiring multiple distinct sources.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The patent's use of plural "sources" could be interpreted broadly to refer to groups of individual emitters that perform different functions, even if integrated onto one device.
    • Evidence for a Narrower Interpretation: The specification and figures depict "light sources" as distinct, packaged components mounted on a substrate (e.g., ’509 Patent, FIG. 1, items 31, 33). This could support a narrower definition where each "source" must be a discrete, separable component, which the complaint alleges is the case in the accused product (Compl. p. 11, ¶35).

VI. Other Allegations

  • Indirect Infringement: The complaint does not set forth specific counts for indirect infringement and lacks detailed factual allegations to support knowledge and intent for inducement or contributory infringement beyond those related to direct infringement and willfulness.
  • Willful Infringement: The complaint alleges willful infringement for all asserted patents. The basis for this allegation is primarily pre-suit knowledge stemming from a series of four detailed warning letters sent by Plaintiff to Defendant and its parent company between November 11, 2024, and March 24, 2025 (Compl. ¶21-25). The complaint alleges these letters identified specific patents, accused the Gavita product of infringement, and included claim charts, but that Defendant continued its infringing activities without providing a substantive response (Compl. ¶22-25).

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

  • A central evidentiary question will be one of technical verification: can Plaintiffs prove through testing and reverse engineering that the accused Gavita products' optical spectra and complex semiconductor micro-structures meet the specific numerical limitations and layered configurations required by the eleven asserted patents? This question spans the entire case, from the mathematical spectral comparisons of the '120 patent to the nanometer-scale layer compositions of the '069 and '868 patents.
  • A key legal question will concern willfulness: did the Defendant's conduct, particularly its alleged failure to substantively respond to a series of detailed warning letters that included claim charts, constitute objective recklessness sufficient to support a finding of willful infringement and potential enhanced damages under 35 U.S.C. § 284?
  • A core issue of claim construction will be one of definitional scope: can terms like "light source" ('509 Patent) and "a same color temperature" ('120 Patent) be interpreted in a way that encompasses the specific design and performance characteristics of the accused products, or will Defendant be able to argue a non-infringing alternative interpretation based on the patents' intrinsic evidence?