Hangzhou Jingyao Technology Co Ltd v. Luster Leaf Products Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Hangzhou Jingyao Technology Co., Ltd. (People's Republic of China)
  • Defendant: Luster Leaf Products, Inc. (Illinois)
  • Plaintiff's Counsel: Veritas Light Law Group, P.C.
• Case Identification: 1:26-cv-4926, N.D. Ill., 04/29/2026
• Venue Allegations: Venue is alleged to be proper because the Defendant, Luster Leaf Products, Inc., is an Illinois corporation that resides and has a regular and established place of business in the judicial district.
• Core Dispute: Plaintiff seeks a declaratory judgment that its electronic soil testing meter does not infringe Defendant's patent and that the patent's asserted claims are invalid.
• Technical Context: The lawsuit concerns electronic soil meters used in gardening to measure characteristics like pH and moisture.
• Key Procedural History: The dispute arose after Defendant Luster Leaf filed a patent infringement complaint on Amazon.com against Plaintiff Jingyao's product, resulting in the product's delisting. Jingyao alleges that its subsequent written demand for retraction was ignored, creating the actual controversy required for this declaratory judgment action. The complaint heavily references the patent's prosecution history, noting that an "averaging" limitation was added to the claims via a 2014 amendment to overcome a prior-art rejection, a fact that may give rise to prosecution history estoppel.

Case Timeline

Date	Event
2006-12-23	Date of Plaintiff's Factory Calibration Work Instruction (Doc. No. SC01)
2009-12-07	'361 Patent Provisional Priority Date
2010-12-07	'361 Patent Non-Provisional Filing Date
2014-03-25	USPTO issues Office Action rejecting claims
2014-06-25	Applicant files "2014 Amendment" adding averaging limitations
2015-01-20	'361 Patent Issue Date
2026-03-01	Defendant files patent infringement complaint on Amazon.com
2026-03-13	Plaintiff sends written retraction demand to Defendant
2026-04-29	Complaint for Declaratory Judgment filed

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

U.S. Patent No. 8,938,361 - "Electronic Gardening Tool and Method of Configuring the Same"

• Patent Identification: U.S. Patent No. 8,938,361, "Electronic Gardening Tool and Method of Configuring the Same," issued January 20, 2015.

The Invention Explained

• Problem Addressed: The patent describes a need for an improved, cost-effective electronic gardening tool, noting that existing digital meters may require expensive factory calibration or extra calibration circuitry to ensure accuracy ʼ361 Patent, col. 1:20-27
• The Patented Solution: The invention describes methods for a self-calibrating soil meter. One embodiment, called "floating calibration," involves the device automatically taking multiple "initial analog readings" when powered on (presumably in the air), averaging these readings to compute a "nominal value," and then using this value as a software-defined "zero reference" for subsequent soil measurements ʼ361 Patent, col. 4:40-54 ʼ361 Patent, FIG. 2 Another embodiment uses a hardware "calibration circuit" to establish a fixed reference ('361 Patent, col. 8:26-30).
• Technical Importance: The described self-calibration method aims to provide reliable measurements over the life of the product without requiring manual user calibration or the high cost of precise factory calibration for each device ('361 Patent, col. 7:35-39).

Key Claims at a Glance

• The complaint challenges independent claims 1 and 16 Compl. ¶15
• Independent Claim 1 (Apparatus):
  • An apparatus for measuring a soil characteristic, comprising a sensor circuit, an ADC, a microcontroller, and a display panel;
  • wherein the microcontroller is configured to: obtain a plurality of initial readings from the sensor circuit when the apparatus is powered on;
  • obtain a nominal value by averaging the initial analog readings; and
  • assign a zero reference associated with a neutral value of the soil characteristic to the nominal value derived by averaging the initial readings.
• Independent Claim 16 (Apparatus):
  • An apparatus for measuring a soil characteristic, comprising a sensor circuit, a microcontroller with an ADC, and a display panel; and
  • a calibration circuit adapted to set a zero reference... to a fixed reference voltage from the sensor circuit by averaging initial analog readings to obtain the neutral value.
• The complaint's analysis also addresses dependent Claim 17 and reserves the right to contest other claims Compl. ¶63

III. The Accused Instrumentality

Product Identification

• The "Jingyao Product," an electronic soil testing meter identified by ASIN B0GFN27XZ1 Compl. ¶2

Functionality and Market Context

• The accused product is a multi-function electronic soil tester that measures soil pH, moisture, temperature, and light levels Compl. ¶36
• The complaint alleges the product's calibration is not performed by averaging initial readings at power-on. Instead, it is calibrated at the factory using four manual trimmer potentiometers that are then permanently fixed Compl. ¶4 For measurement, the product allegedly uses a three-sample median filter continuously on its readings as a form of real-time outlier rejection, not to establish a baseline reference Compl. p. 14, in chart Final display values are derived from raw sensor data via fixed, hardcoded lookup tables in the firmware Compl. p. 14, in chart
• The complaint alleges the product is significant to Plaintiff's U.S. business and that its delisting from Amazon.com has caused substantial and ongoing harm Compl. ¶34
• No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

The complaint seeks a declaratory judgment of non-infringement. The tables below summarize the Plaintiff's asserted points of non-infringement.

U.S. Patent No. 8,938,361 Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Non-Infringing Functionality	Complaint Citation	Patent Citation
[1.e] wherein the microcontroller is configured to: obtain a plurality of initial readings from the sensor circuit when the apparatus is powered on;	The product's firmware does not acquire a dedicated set of "initial readings" for calibration upon power-on; it instead enters its main operating loop and begins periodic measurements.	¶36	col. 4:40-45
[1.f] obtain a nominal value by averaging the initial analog readings; and	The firmware never computes a "nominal value" by averaging. It applies a three-sample median filter to consecutive readings during ordinary measurement, which is not an arithmetic mean used to establish a baseline.	¶36	col. 4:49-50
[1.g] assign a zero reference associated with a neutral value of the soil characteristic to the nominal value derived by averaging the initial readings.	The firmware does not assign or store a "zero reference" or "neutral value." Raw sensor values are converted for display using fixed, hardcoded lookup tables.	¶36	col. 4:50-54

U.S. Patent No. 8,938,361 Infringement Allegations

Claim Element (from Independent Claim 16)	Alleged Non-Infringing Functionality	Complaint Citation	Patent Citation
[16.d] a calibration circuit adapted to set a zero reference associated with a neutral value of the soil characteristic to a fixed reference voltage from the sensor circuit by averaging initial analog readings to obtain the neutral value.	The product allegedly lacks this element for three independent reasons: (1) no "calibration circuit" is connected to the microcontroller, only passive factory-set potentiometers; (2) there is no "fixed reference voltage from the sensor circuit"; and (3) there is no "averaging [of] initial analog readings."	¶36; ¶37	col. 8:26-67

• Identified Points of Contention:
  • Scope Questions: A central question is whether the accused product's use of a "three-sample median filter" during ongoing measurement can be considered equivalent to "averaging the initial analog readings" at power-on to set a baseline, as required by the claims.
  • Technical Questions: The complaint raises the question of whether passive, factory-adjusted trimmer potentiometers that are not electronically connected to the microcontroller can meet the definition of a "calibration circuit adapted to set a zero reference... by averaging," suggesting a potential mismatch in both structure and function Compl. p. 15-16, in chart Compl. ¶37

V. Key Claim Terms for Construction

• The Term: "averaging the initial analog readings"

• Context and Importance: This term appears in both asserted independent claims (1 and 16) and was added during prosecution to overcome a prior-art rejection Compl. ¶¶24-25 Its construction is therefore central to both infringement and validity. The dispute will likely focus on whether this requires a specific mathematical operation (arithmetic mean) at a specific time (power-on initialization) for a specific purpose (setting a baseline).

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: The patentee may argue that "averaging" should be given a broader meaning to encompass various methods of finding a central tendency from initial sensor data. The specification refers to "averag[ing] these initial analog readings to derive a nominal value" without explicitly limiting the term to an arithmetic mean ʼ361 Patent, col. 4:49-50
  • Evidence for a Narrower Interpretation: The plaintiff argues that the prosecution history, where the applicant distinguished this "averaging" step from the prior art's iterative process, supports a narrower definition Compl. ¶¶26-27 The complaint also points to the provisional application, which allegedly distinguished a power-on "fast series of reads" from a "weighted average formula" used for display smoothing, suggesting the inventors contemplated distinct, specific processes Compl. ¶¶51-53

• The Term: "calibration circuit"

• Context and Importance: This term is a key structural element of Claim 16. The plaintiff alleges its product, which uses passive potentiometers, does not have this circuit Compl. ¶37 The case may turn on whether these potentiometers qualify as the claimed "circuit."

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: A patentee might argue that any collection of components, including the potentiometers, that serves to calibrate the device constitutes a "calibration circuit." The patent depicts a "calibration circuit 824" that includes a variable resistor ʼ361 Patent, FIG. 10
  • Evidence for a Narrower Interpretation: The plaintiff argues that a "calibration circuit" under Claim 16 must be "adapted to" perform the function of "averaging," which it alleges its passive, factory-set potentiometers do not do Compl. p. 16, in chart Furthermore, the complaint contends that the patent specification discloses two mutually exclusive embodiments-one with software averaging and no circuit, and one with a hardware circuit that performs no averaging-and therefore fails to describe the claimed combination of a circuit that averages Compl. ¶¶57-59

VI. Other Allegations

• Indirect Infringement: The complaint does not allege indirect infringement. However, it preemptively argues that the doctrine of equivalents is barred by prosecution history estoppel. The complaint alleges that the "averaging" limitation was a narrowing amendment made to overcome a prior-art rejection, which creates a presumption of surrender of subject matter that does not literally meet the "averaging" requirement, such as the accused product's alleged median filtering and factory-set potentiometers Compl. ¶¶40-43
• Willful Infringement: This allegation is not applicable in a declaratory judgment action brought by the accused infringer. The basis for the "actual controversy" is Defendant's pre-suit enforcement activity via an Amazon.com complaint, which placed Plaintiff on notice of the infringement allegations Compl. ¶30

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

This declaratory judgment action appears to center on a small number of critical, interrelated issues of claim construction and validity. The key questions for the court will likely be:

• A core issue will be one of definitional scope and estoppel: Will the term "averaging the initial analog readings," which was added during prosecution to secure the patent, be interpreted narrowly as a specific power-on, baseline-setting calculation? If so, prosecution history estoppel may prevent the patentee from using the doctrine of equivalents to capture the accused product's alleged use of a continuous median filter for outlier rejection.

• A second key question will be one of structural and functional scope: Do the accused product's passive, factory-set potentiometers constitute a "calibration circuit adapted to... [perform] averaging" as required by Claim 16, or is there a fundamental mismatch in both the physical structure and the recited function?

• Finally, the case raises a significant validity question under § 112: Does the patent's specification provide adequate written description for the combination recited in amended Claim 16-a hardware circuit that performs averaging-when the complaint alleges the specification only describes two separate, mutually exclusive embodiments: (1) software averaging without a circuit, and (2) a hardware circuit without averaging?