Determination of whether an element in a design patent is purely functional

1. A design patent provides patent protection mainly for a creation made in respect of one or a combination of the shape, pattern, and color of an article to achieve visual appeal. If the shape of an article is purely functional, meaning the shape depends entirely on the function of the article and does not allow any freedom of creation in visual appearance, the shape is not a subject matter to be protected by a design patent.

2. Whether the shape of an article is purely functional depends on the basic shape of a must-fit portion of a conventional article. If the entire design of the former shape is an inevitable result of creation in order to enable coupling with, or mounting with respect to, the conventional article and does not involve any creative idea, the former shape should be determined as purely functional and therefore should be denied a design patent.

3. As can be known from this case and explanations of the examination guidelines, whether an element in a design patent is purely functional can be determined by determining whether there is a conventional article whose shape not only corresponds to the element, but also is the only shape that enables a must-fit relationship. If a must-fit article can be found, the chance of the element being viewed as purely functional is high. For example, the design of a bolt may be purely functional if its design feature is dictated entirely by the thread feature of a conventional nut.

I. Issue:Is the shape of the article in the design patent at issue purely functional?

II. Judgment No.: 2021 Min-Zhuan-Su Zi No. 40

III. Patent at issue:D195617

IV. Case summary

1. Representative drawing of the patent at issue

2. The plaintiff’s claim:The shape of the driving end in the patent at issue can be changed in various ways.

Certain oil sump plugs have a “single horizontal groove” in a central portion. Therefore, the driving end of a tool for removing such a plug may be provided with only an engaging projection configured to be engaged in the single horizontal groove, or the driving end of the removing tool may be provided with only a curved engaging protuberance but “does not have an engaging projection configured to be engaged in the single horizontal groove”. Moreover, the engaging projection may be a single straight rib that extends linearly or a plurality of protruding blocks that are linearly arranged at intervals, wherein the periphery of the rib or the periphery of each protruding block may be rectangular, curved, or in other shapes, and wherein each protruding block may be in the form of a rectangular post, a cylinder, or a post of another shape.

3. The defendant’s claim:

The outer configuration claimed in the patent at issue is merely the shape of a structure corresponding to the plug.
The “curved engaging protuberance” design feature of the patent at issue corresponds to the “movement groove 20” design feature of defendant’s citation 1, and the two projecting design features (indicated by dashed lines) of the patent at issue correspond to the “recess 32” design feature of defendant’s citation 1. It is obvious that the outer-configuration features of the patent at issue are designed solely in response to the structure and removal of the plug in defendant’s citation 1 and are therefore purely functional.
Before the application for the patent at issue was filed, defendant’s citations 1 and 2 already disclosed a threaded locking member and a plug that match, and can be used with, the removing tool of the patent at issue. In practice, defendant’s citation 3 is also sufficient to disclose that the ET1604G removing tool has a corresponding Mercedes Benz engine oil sump plug 0029902017 and is designed in shape to match the structure of, and be used with, the Mercedes Benz plug.

4. Court judgment:

(1) The removing tool of the patent at issue does not have a must-fit relationship with a conventional oil sump plug structure.
It can be known from the drawings of the patent at issue and the outer configurations of the product at issue that the driving end of the article for removing an oil sump plug may have different outer configurations. In other words, the differently shaped removing tools are equally capable of driving a threaded locking member or plug identical to that disclosed in defendant’s citation 1. Therefore, the outer configuration of the removing tool of the patent at issue does not have a must-fit relationship with the outer configuration of a conventional threaded locking member or plug.

(2) The removing tool of the patent at issue not only is functional, but also allows its outer configuration to be designed selectively to achieve the intended visual appeal.
The removing tool can be designed in many possible ways, i.e., may have a diversity of designs in terms of its outer configuration, and yet the differently shaped removing tools are equally capable of performing the same function or similar functions. Hence, in addition to having the function of removing an oil sump plug, the removing tool allows changes in creation of its outer configuration, e.g., of its shape or surface decoration. That is to say, the outer configuration of the removing tool does not depend entirely on a basic shape that results from functional considerations to enable a must-fit. The defendant’s foregoing defense, therefore, is not justified. The removing tool of the patent at issue should be viewed as having a visual feature as well and hence as a creation made for visualappeal.