Date:13 July 2023

【Volume 114】

A parameter claim refers to a patent defining its technical feature of the claim with physical or chemistry parameters, which is particularly common in the material field due to the difficulty of defining the feature by structure or chemical formula. However, the options for defining parameters are quite diverse, and applicants often create various parameters by themselves. Therefore, parameter claims would be judged differently from common inventions when they are compared with technical features of prior art.

In follows, the trends on practical judgment of parameter claims in China is analyzed through several recent cases.

Case Facts

(1) The parameters used must be those that can be clearly and reliably defined by a person skilled in the art according to the teachings of the specification or through normal technical means

Case 1：Invalidation decision on invention patent “Heat curable resin composition for light reflection” (Publication No. CN101535366B, the ‘366 patent)ⁱ

Claim 1 in the ‘366 patent defines the following technical features:

　“the length of burrs caused upon transfer molding under conditions of molding temperature 100oC to 200oC, molding pressure not more than 20 MPa, and molding time 60 to 120 sec is not more than 5 mm”.

Claim 1 in the ‘366 patent defines the measurement condition of the length of burrs, but there is no illustration and explanation of the length of burrs in the description of the ‘366 patent. Therefore, the China National Intellectual Property Administration (CNIPA) deemed that the limitation of the measurement condition of the length of burrs in Claim 1 of the ‘366 patent cannot clearly and explicitly express the claimed invention, and does not clearly define the scope of the claim, which violates the rule of the “definiteness requirement”.

In particular, the CNIPA（China National Intellectual Property Administration）points that when using parameters, the parameters used must be those that can be clearly and reliably defined by a person having ordinary skill in the art according to the teachings in the specification or through the normal technical means in the art. In general, the terms used in the claim should be interpreted with the meaning normally comprehended in the related technical field. In certain circumstances, if a term is specified in the specification as having a specific meaning and the term is used in the claim, the term must be described in a sufficiently clear manner in the specification.

(2) The problems to be solved, the effects achieved, and the normal means used by a person having ordinary skill in the art should be combined together to determine whether the exhibit has disclosed the parameters of the patent at issue

Case 2：Invalidation decision on invention patent “Polyolefin microporous membrane” (Publication No. CN101331178B, the ‘178 patent)ⁱⁱ

　Claim 1 in the ‘178 patent defines the following technical features:

　“ A microporous polyolefin film having a thickness of 1 μm (inclusive) to 50 μm (inclusive), a porosity of 30% (inclusive) to 70% (inclusive), a piercing strength of 0.15 N/μm or more in terms of a film thickness of 1 μm, tensile strengths in the length direction (MD tensile strength) and the width direction (TD tensile strength) of 30 MPa or more respectively, a thermal shrinkage in the width direction (TD thermal shrinkage) at 65° C of 1% or less., and a thermal shrinkage ratio in the length to width direction (MD/TD thermal shrinkage ratio) at 65° C of more than 2,

　wherein tensile elongations in the length direction (MD tensile elongation) and the width direction (TD tensile elongation) are each 10% (inclusive) to 200% (inclusive); and the total of the MD tensile elongation and TD tensile elongation is 20% (inclusive) to 250% (inclusive). ”.

The main issue in this case is that the “shrinkage” disclosed in the exhibit was measured at 135℃, instead of 65℃ as defined in the ‘178 patent. Therefore, the patentee claimed that the relevant technical features were not disclosed in the exhibit.

However, the CNIPA held that although the “shrinkage” disclosed in the exhibit was measured at 135℃, the purposes of defining the “shrinkage” of the ‘178 patent and the exhibit are both to prevent shrinkage in the width direction. Thus, a person having ordinary skill in the art may conceive to adjust and define the thermal shrinkage at 65℃ and is therefore able to prevent the shrinkage in the width direction, and further improve the safety of the battery. As a result, the CNIPA deemed that the ‘178 patent does not involve an inventive step.

Obviously, the CNIPA does not examine the parameter claims merely based on whether the disclosure content of the exhibit corresponds exactly to the parameter, but rather combines the technical problem to be solved, the technical effect achieved, and the normal means of a person having ordinary skill in the art, to comprehensively examine whether the parameter is disclosed.

(3) Whether the parameters can significantly change and improve the structure and/or performance is the key to judging whether it has an inventive step

Case 3：Invalidation decision on invention patent “Mold release film” (Publication No. CN101678605B, the ‘605 patent)ⁱⁱⁱ

Claim 1 in the ‘605 patent defines the following technical features:

　“ For the surface properties of at least one of the surfaces, a maximum height roughness (Rz) of the roughness curve is 0.5 to 20 μm and an average length (RSm) of the roughness curve element is 50 to 500 μm as measured in accordance with JIS B0601:2001 by using a sensing pin having a tip radius of 2 μm and a conical taper angle of 60 DEG under such conditions that the measurement force is 0.75 mN and a cut-off values λs＝2.5μm and λc＝0.8mm. ”.

The technical feature that distinguishes Claim 1 of the ‘605 patent from Exhibit 1 is the difference in the parameters (RZ and RSm) and ranges thereof measured under the specific conditions defined in the claim.

However, the CNIPA held that the purpose of selecting the specific ranges of the two parameters, Rz and RSm, in the ‘605 patent was to ensure the performance of the film product, rather than the technical difficulty of realizing the mold release film structure with the two parameter ranges. In view of the fact that Exhibit 1 is concerned with the same properties as the‘605 patent, such as wrinkle resistance, mold releasability and flowability of the adhesive, a person having ordinary skill in the art cannot find any substantial difference of wrinkle resistance and mold releasability between the‘605 patent and Exhibit 1. Therefore, even though different parameters were chosen to characterize the mold release film product, the change did not result in a significant change or improvement in the performance of the mold release product compared to the prior art.

Case 4：Invalidation decision on invention patent “Lithium-ion battery” (Publication No. CN108832075B, the ‘075 patent)^iv

Claim 1 in the ‘075 patent is as follows:

“ A lithium-ion battery comprising a positive electrode plate, a negative electrode plate, a separator and an electrolyte, the positive electrode plate comprising a positive current collector and a positive film, the positive film being provided on at least one surface of the positive current collector and comprising a positive active material, the negative electrode plate comprising a negative current collector and a negative film, the negative film being provided on at least one surface of the negative current collector and comprising a negative active material l;

wherein,

the positive active material comprises a material with a chemical formula of Li_aNi_xCo_yM_1-x-yO₂, M is one or two selected from Al and Mn, 0.95≤a≤1.2, 0＜x＜1, 0＜y＜1, 0＜x+y＜1, the negative active material comprises graphite, and an OI value of the positive film represented by OI_c and an OI value of the negative film represented by OI_a satisfy a relationship: 0.05≤OI_a/OI_c≤10;

wherein,

OI_c=C₀₀₃/C₁₁₀, C₀₀₃ represents characteristic diffraction peak area of (003) crystal plane in X-ray diffraction pattern of the positive film, C₁₁₀ represents characteristic diffraction peak area of (110) crystal plane in X-ray diffraction pattern of the positive film;

OI_a=C₀₀₄/C₁₁₀, C₀₀₄ represents characteristic diffraction peak area of (004) crystal plane in X-ray diffraction pattern of the negative film, C₁₁₀ represents characteristic diffraction peak area of (110) crystal plane in X-ray diffraction pattern of the negative film .”.

The ‘075 patent defines the claims by the parameters of the OI values of the positive and negative film, while limiting the relationship between the OI values of the positive and negative film (an OI value of the positive film represented by OI_c and an OI value of the negative film represented by OI_a satisfy a relationship: 0.05≤OI_a/OI_c≤10).

The invalidation petitioner asserted that the OI_c and OI_a values described in claim 1 are the physical-chemical parameters of the positive and negative films, respectively, but the positive and negative films do not involve materials with a new material structure and therefore cannot be defined in terms of physical-chemical parameters. In addition, the patentee creates an uncommon parameter (the ratio of the OI value of the positive film to which of the negative film) to define the invention, causing it being unable to be compared with the exhibits.

In this regard, the CNIPA Office considered that “OI_a and OI_c are used to characterize the degree of accumulation and orientation of the positive and negative active substances in the negative and positive films, respectively. The degree of accumulation and orientation of such active substances in the films is not a structural feature of the active material itself, but rather the state of its presence on the electrode film. The value of OI_a and OI_c represents the presence, and OI_a/OI_c shows the matching of the degree of accumulation and orientation of the active substances in the positive and negative electrode films.”. Hence, the description of the parameter defined in the ‘075 patent is determined to be reasonable.

Moreover, regarding an inventive step, the CNIPA stated, “The key to this technical solution of the ‘075 patent is to control the ratio range of the OI value of the positive and negative electrodes so that OI_a/OI_c (the aforementioned “ratio”) is between 0.05 and 10, which enables the lithium-ion battery to achieve an optimal match between the kinetics of the positive and negative electrodes during the rapid charging process.”. However, each exhibit only involves a positive electrode or a negative electrode respectively, without the relevant content of the other electrode, nor does it involve the matching of the OI values of the positive and negative films. Thus, it is determined to have no motivation to combine the exhibits.

From these cases, it can be found that the main factor of the CNIPA's determination on an inventive step is whether adopting the parameters can result in significant structural and/or performance change and improvement, which is therefore the key point to determine whether the patent involves an inventive step.