For companies and individuals, no matter when they files a design patent for their own products or when their own design patents are declared invalid, it often involves the determination of whether the patented design and the comparative design are substantially identical.

Infringement of a design patent requires that the infringing design is identical or substantially identical as the patented design in the eye of anormal consumer. Further, when determining whether a design is substantially identical, the ordinary beholder must make a "comprehensive judgment", based on the design feature(s) of each design, in view of the overall visual effect of the design. The judgment of whether the two are identical is relatively simple, while the judgment of whether the two are substantially identical is relatively complicated. 

The Chinese Guidelines Patent Examination enumerates several situations of substantially identical.

According to the Guideline, the judgment of substantially identical designs is only limited to designs of the same or approximate category of products. If a normal consumer can see from the overall observation of the patent concerned and the comparative design, that their difference simply falls into the following circumstances, then the patent concerned and the comparative design are substantially identical:

(1) the difference lies in only slight changes in some fine details which cannot be noticed paying normal attention, for example the designs of venetian blind differ only in the number of slats;

(2) the difference exists in the parts which cannot be seen easily or cannot be seen at all when in use, however, the circumstance where there is evidence showing that the special design in the parts which cannot be seen easily has notable visual effect for a normal consumer makes an exception;

(3) the difference is a result of the substitution of one design element as a whole by said design element of the usual design commonly known for the category of product, for example, changing the shape of a cookie jar with pattern and colour from the cube to the cuboid;

(4) the difference exists in that the patent concerned is simply a repeated and continuous arrangement or an increase/decrease in the continuous number of the comparative design as a design unit following the normal arrangement of the category of product, for example, repeated and continuous arrangement of the rows of the seat in cinema or an increase/decrease in the number of the rows of seats; and

(5) the difference exists in that the patent concerned and the comparative design are a mirror image.

In judging whether designs are identical or similar, we shall consider in a comprehensive manner according to the overall visual effect of the designs on the basis of the design features of the patented design and the design alleged for infringement.

According to the principle of comprehensive judgment, it is required to judge the differences not only from the fine details but from the overall design changes of the patented product.

The “slight changes in fine details” mentioned in the above point (1) is always an important and controversial point when judging whether the designs are substantially identical.

Taking the following Chinese invalidation case "lubricating oil barrel" as an example:

Involved patent                       Comparative design

We can see that the overall shape of the involved patent and the comparative design are basically the same. The only difference lies in the presence or absence of the lid, and the overall design is the innovation point of the product, not only a lid. Therefore, the invalidation decision held that the above-mentioned differences were slight changes in some fine details that could not be noticed by ordinary consumers with ordinary attention, and the two were substantially identical.

A concept “slight changes in fine details” is mentioned in the above case. It normally more complicated in practice about how to judge “slight changes in fine details”.

In another case, there are two design patent applications in a "gourd watch" case. The difference between the two is only that the dragon and phoenix shapes of the gourd head are different. But it is different from the difference in the "lubricating oil barrel" invalid case and is not a slight change in some fine details. This is because the dragon and phoenix on the head of the gourd are the design innovation of the product compared to the simple "gourd" shape. The difference in the shape of the dragon and the phoenix is not a slight change, and the two design patent applications are not substantially identical.

Patent 1: Gourd Watch (dragon head)     Patent 2: Gourd Watch (phoenix head)

It can be seen that although the distinguishing features occupied a small area, different conclusions can be drawn whether the distinguishing feature belongs to slight changes in some fine details because the distinguishing features belong to an innovation point in this case. The author believes that when the same points constitute an innovation point of a product, the different point is a fine detail; when the different point is an innovation point of a product, the different point may no longer be slight change because it is an innovation point.

Overall visual and comprehensive judgment is the basic principle for judging whether the design patents are substantially identical. According to the principle of overall visual, the slight change in fine details is that the location of the difference is partial and occupies a small proportion of the area, which is not an innovation point of a design. According to the principle of comprehensive judgment, the subject of judgment is required to judge the distinguishing features of the patented design and the comparative design not only from the fine details but from the overall design changes of the patented product. The author believes that in practice, we can consider the following two points to judge if the distinguishing feature belongs to slight changes in some fine details: (a) whether the distinguishing point is an innovation point of a design and if yes, even if it is fine details, the area occupied is a small proportion of a product, it is not a slight change; (b) whether the distinguishing point is a common design of a product, and if yes, even if it can be noticed by ordinary consumers with general attention, it is still easy to be ignored.