1Brief Introduction

Generally, a technical feature of product invention is defined as a structural feature or a parameter feature, and a technical feature of process invention is defined as a process feature. If a technical feature cannot be defined accurately by the above manner, or an invention cannot be duly protected by way of the above manner, a technical feature defined by function may be used in a claim. In short, a feature of function is that defined by its function and/or effect to be achieved.

During patent examination procedure in China, what are the requirements for features defined by function? What problem we might meet during substantive examination? What should we pay attention to when drafting an application document? These problems will be discussed hereinafter.

2Relevant Regulations and Analysis

Guidelines for patent examination, II-2, 3.2.1, provides detailed regulations to features defined by function. Specifically, the main criteria are listed as follows.

  1. “Usually, for product claims, features of function or effect shall be avoided as far as possible to be used in defining the invention. It is only when a certain technical feature cannot be defined by a structural feature, or it is more appropriate to be defined by a feature of function or effect than by a structural feature, and the function or effect can be directly and affirmatively verified by experiments or operations as stated in the description or by customary means in the art, that definition by features of function or effect in a product claim can be permissible;”
  2. “Technical feature defined by function in a claim shall be construed as embracing all the means that are capable of performing the function;”
  3. “If the description merely states in vague terms that other alternative means may be adopted, but the person skilled in the art cannot understand what they might be or how they might be used, then the definition by function in the claims is not permitted;”
  4. “Claim of pure functional definition cannot be supported by the description, and therefore is not permitted.”

According to the above regulations, following requirements should be noticed when using features defined by function.

  1. The usage situation should be aware of. In a process claim, there is no special requirement for the feature defined by function. In a product claim, it is only when a certain technical feature cannot be defined by a structural feature, or it is more appropriate to be defined by a feature of function or effect than by a structural feature, and the function or effect can be directly and affirmatively verified, that definition by features of function or effect can be permissible.
  2. Once a technical feature is defined by function, it is construed as embracing all the means that are capable of performing the function. The description should provide sufficient support for the technical feature.
  3. Besides an implementation manner which is described in the description in detail, other alternative means should also be definitely described in the description.
  4. The feature defined by function cannot be used independently, it shall be accompanied with structural features or process features.

3Types of Office Actions Frequently Received

Usually, an office action relating to features defined by function may include the following two kinds of comments:

  1. as to a feature defined by function, the examiner determines whether a person skilled in the art could know an existing manner for implementing the function, and whether other means covered by the function (except for the implementation manner described in the description) are capable of performing the same function and achieving the same technical effect as the implementation manner. If not, it would be regarded that the claim containing the feature defined by function cannot be supported by the description;
  2. the examiner determines whether the claim merely defines objective or effect to be achieved by features of function but does not provide any actual technical feature for achieving the objective or effect. If yes, it would be regarded that the claim cannot be supported by the description.

4What Should We Pay Attention to When Drafting an Application Document

In order to avoid the above types of office actions, the applicant is proposed to notice the following two points when drafting an application document.

  1. As to a feature defined by function, it is advisable to describe implementation manners relating to the feature as many as possible in the description. For each one, principle and procedure for implementing the function shall be described in detail. When there are multiple equivalent embodiments, one or two exemplary embodiments may be selected and described in detail, and others may refer to the exemplary embodiments and have their unique characters be described additionally.
  2. As to each implementation manner of the feature defined by function, the applicant may consider to draft at least one dependent claim for the manner. Thus, if such feature is rejected during substantive examination or patent invalidation, the applicant have an opportunity to select an appropriate dependent claim as an amendment basis. In addition, during an infringement lawsuit, the patentee may match the dependent claim including the implementation manner to a specific component of an infringing product, which facilitates the court to judge whether the infringing product falls within the protection scope of the patent.