Judicial Interpretation on Sufficiency of Disclosure for Claims Involving Multi-Variable Equations

Case in Brief

In a recent landmark case (2021) revealed in IP Administrative Final Judgment No. 1071 by the Supreme People’s Court (最高法知行终1071号), which involves Shenzhen Haipengxin Electronics Co., Ltd. (hereinafter referred to as “the Plaintiff”) against  China National Intellectual Property Administration (hereinafter referred as “CNIPA”) and the proprietor of the disputed patent (CN100530868C), the Supreme People’s Court has provided significant insights into the evaluation criteria for sufficiency of disclosure for claims defined by multi-variable equation(s).

The Supreme People’s Court ruled that when a claim is limited by equation(s) containing two or more variables, the specification must clearly define the relationship between these variable selections, their interrelations and how they relate to technical effects. Simply presenting the equation(s) alone would not necessarily lead to a clear protection scope of the claim. Instead, the description and drawings should illustrate specific embodiments and other relevant explanations to reasonably interpret the scope of claims and establish the extent of protection accordingly.

In its final judgment, the Supreme People’s Court overturned the first-instance judgment and the previous invalidation decision made by  CNIPA, and ordered a retrial for the invalidation proceedings against the disputed patent.

Technical Background and Specifics

The case in question revolves around a patent for a stacked graphite discharge gap device, which is designed to reduce uncertainties in calculating capacity values for various lightning current waveforms.

The core of the dispute lies in how the capacity value of the capacitors within the π-shaped connection capacitor group is calculated using a multi-variable equation , wherein

• represents the induced discharge current;
• is the frequency of the lightning waveform;
•  denotes the rated voltage; and
•  is the safety factor, and .

Key Issues in the Dispute

• Sufficiency of Disclosure: The Plaintiff argued that the specification did not adequately disclose the range and determination methods for the parameters and . Specifically, the safety factor  could take on a wide range of values, leading to significant uncertainty in the calculation of the capacitor capacity .
• Technical Uncertainty: The Plaintiff contended that without clear guidelines for selecting and , it would be impossible for those skilled in the art to implement the invention consistently. For instance, the Plaintiff pointed out that the safety factor  ranged from positive polarity 162 to negative polarity 1588 in embodiments, making it impractical to select appropriate values.
• Specific Examples: The Plaintiff also highlighted that while four specific examples were provided in the specification, they did not cover all possible scenarios or explain why certain values were chosen for and .

Key Points from the Judgment

• Technical Features Defined by Equations

When a claim includes technical features defined by an equation containing two or more variables (i.e., parameters), the specification must clearly describe the relationship between the selected numerical ranges and the technical effects achieved.

• Disclosure of Parameters

Within the numerical range related to the parameters in the equation, all values should be disclosed to the extent that they can achieve the expected technical effects without excessive effort. Practitioners should be able to determine whether the claimed technical effects are achieved when implementing the invention. If specific examples provided in the specification only disclose certain values, it cannot be presumed that the corresponding technical effects will be obtained for all disclosed values.

• Sufficiency of Disclosure for Methods Involving Parameters

For the sufficiency of disclosure regarding methods involving parameters, if the method used is not habitual, the specification must provide more detailed information. If the information about the parameters is unclear, practitioners may not be able to identify the necessary technical means to solve the problem of the invention based on the entire disclosed content and common technical knowledge. Therefore, the specification does not meet the requirement of sufficient disclosure.

Judgment Rationale—Sufficiency of Disclosure

• Parameter Definitions: The patent specification must provide clear definitions for all parameters used in the equations. For example, (induced discharge current),  (frequency of the lightning waveform),  (rated voltage) and  (safety factor) must be explicitly defined.
• Interrelations and Technical Effects: The specification should explain how different values of these parameters affect the overall performance of the invention. This includes demonstrating the relationship between parameter choices and the resulting technical effects. Without this information, it would be impossible for those skilled in the art to implement the invention without excessive experimentation.
• Specific Examples: Detailed examples demonstrating practical applications under varying conditions are crucial. The Supreme People’s Court noted that while four specific cases were examined, they did not cover all possible scenarios or explain why certain values were chosen for and .

Practical Implications

This case highlights the importance of thorough documentation in patent applications, especially when complex mathematical relationships are involved. It serves as a reminder that merely providing an equation is insufficient and applicants shall offer sufficient contexts through detailed descriptions and practical examples.

Furthermore, this judgment underscores the necessity for inventors and patent attorneys to ensure that their patent specifications include comprehensive information about the selection and determination methods of key parameters. Without adequate disclosure, the validity of the patent may be challenged, which would be vulnerable to invalidation.