A design patent protects the creation of an article's appearance that can be exploited by industries. During product developments, many similar designs for the appearances of the products may be further developed under the same design concept. These similar designs evolved based on the same design concept should have the same value as the original design and thus the same protection may be acquired for the similar designs as the original design. To this end, the Taiwan Patent Act has introduced the derivative design system for the designs that are similar to and developed from the original design. By filing derivative design patent applications based on the original design, it is possible to obtain the protection of multiple designs that are similar to each other and to the original design and are developed under the same design concept.
 
Similar systems may be found under the US Patent Act and the Japan Design Act even though differences exist among these systems. The US Patent Act allows one design application including multiple designs and continuation/continuation in part application; and the Japan Design Act have the related design system to protect the similar design stemming from the original design. However, differences exist among these systems. This article introduces the derivative design patent in Taiwan and briefly compares the Taiwan derivative design patent and the similar systems in the US and Japan.

Derivative design patents in Taiwan
The Taiwan patent system has adopted the first-to-file principle; and derivative designs can be considered an exception to the “double patenting” for the owner of a design patent right. Paragraph I of Article 127 of the Taiwan Patent Act stipulates that “For two or more similar designs owned by the same person, applications may be filed for a design patent and its derivative design patent(s).” Therefore, if the same person has two or more similar designs, a proper approach to acquire the most extensive protection for these similar is filing a design patent application for the original design and one or more derivative design patent applications for the other similar designs.

(1) Patent scopes of derivative designs
According to Article 127, Paragraph IV, of the Taiwan Patent Act, “An applicant shall not file a patent application for derivative design patent if the design therein is only similar to another derivative design patent but not to the original design patent.” Where the same person develops a further design similar to the derivative design, he or she may file a further derivative design patent application based on the derivative design patent application provided that such further derivative design is also similar to the original design. However, if the further derivative design is not similar to the original design, then such further derivative design shall not be allowed as the derivation design based on the original design application.
 
Derivative designs play an important role on interpretating the patent scopes of the derivative designs and the parent design. Generally speaking, derivative designs function to confirm the protection scope of the original design and further expand the protection scopes of similarity of the claimed designs. Article 137 of the Patent Act provides that “The right of a derivative design patent may be claimed independently, and its effect shall be extended to the scope of similarity.” Since the appearances of the original design and the derivative designs shall be similar, the original and derivative designs share the common features leading to the similarity of the designs; and these common features should be novel, unique and have not been disclosed in the prior art. It should bear in mind that the common features found in the derivative designs and the original designs have relatively significant impact on the overall appearance of the design. When constructing the patent scopes of the original and derivative designs, such common features shall have more weights on the overall visual effects of the designs than the other features.

The scopes of the original design and its derivate designs may be presented by the figure below:

O: Original design
D1: Derivative design of O (D1 shall be similar to O)
D2: Derivative design of D1 (D2 shall be similar to O and D1)

(2) Timing for filing a derivative design patent application
Timing is important if applicants want to file derivative design patent applications. A derivative design patent application shall be filed after the original design patent application has been filed[1] and before the publication of the original design patent application[2]. However, according to the information released by the Taiwan Intellectual Property Office (TIPO), on average, the pendency of a design patent application at the TIPO is 12 months[3], sometimes even shorter. Applicants have very limited time on considering whether to file derivative design patent applications.
(3) Patent terms of derivative designs
As stated in the foregoing, the right of a derivative design patent may be claimed independently, and its effect shall be extended to the scope of similarity. However, it shall be particularly noted that the patent term of a derivative design expires simultaneously with the original design patent³ thereby the patent term of the original design cannot be extended by consecutively filing derivative design patent applications. Moreover, special cares shall be taken to keep the original design alive if the patent owners want to excise the patent rights of the derivative designs.

Related designs of Japan
Similar to the derivative design patents in Taiwan, the related design system under the Japan Design Act provides the protection for the designs similar to the fundamental or principal designs. According to Article 10, Paragraph (1), of Japan Design Act, “An applicant for design registration may obtain design registration of a design that is similar to another design selected from the applicant's own designs either for which an application for design registration has been filed or for which design registration has been granted, ….” Japan also adopts the principle of the first-to-file system. That is to say, if multiple designs are developed under the same design concept, only the first selected design can receive design registration, the other designs, either the designs developed simultaneously as the first selected design or evolved subsequently on different days, cannot be registered under the principle of the first-to-file. However, the related design system is an exception to this principle.

In 2019, the Japan Design Act introduced several major amendments to the related design system, i.e., allowing the related designs be filed after the principal design has been registered and published, allowing consecutively filing the related designs and extending the duration of protection of design rights to 25 years. By ways of these amendments, the Japanese related design system can significantly strengthen the protections of the similar designs and the relevant principal design.

Under the related design system in Japan, a related design shall be filed after the filing date of the principal design and within 10 years after the filing date of the principal design application[4]. With respect to the patent term of a related design, the duration of design right of a related design shall be expired as the principal design and 25 years after the filing date of the principal design[5]. Moreover, the Japan Patent Act allows consecutively filing a further related design linking to a related design; and the further related design shall certainly be similar to the related design but may not be required to similar to the principal design of the related design[6].
The patent scopes of the principal design and its related designs may be presented by the figure below:

P: Principal design
R1: Related design of P (R1 shall be similar to P)
R2: Related design of R1 (R2 shall be similar to R1 but is not required to be similar to P)

In view of the foregoing, the Japan Design Act allows consecutively protections for related designs; that is to say, Secondly, based on the Japan Design Act, the duration of the design right of a related design patent is 25 years from the filing date of the principal design. Moreover, the related designs applications may be filed within 10 years after the filing date or priority date, if priority is claimed, of the fundamental design application. Consequently, applicants are able to dynamically deploy the patent portfolios based on the developments of the relevant products in the markets.