1. An excerpt from the Judgment (doctrine of equivalents)
[Regarding the first and second requirements for equivalence]
In light of such technical idea of the Present Invention, even if a shaft hole formed on a pair of branch parts does not communicate with the recessed part of the handle body, when the handle is constituted by the handle body having the recessed part and the handle cover covering the recessed part, the technical problem caused by the conventional structure can still be solved; therefore, it cannot be said that replacement of this structure by another structure makes the technical idea different from that of the Present Invention as a whole. Further, even if a beauty instrument does not employ a structure where “a shaft hole communicates with a part of a handle”, but a structure where a shaft hole does not communicate with a part of handle like the defendant’s new product, it does not change the fact that molding accuracy and strength of the handle can be well maintained, and workability of assembly work of the handle is improved as in the case of the Present Invention. Accordingly, the difference between the Present Invention and the defendant’s new product (different part) is not an essential part of the Present Invention (satisfaction of the first requirement)”, and even if the structure of the Present Invention is replaced with the structure of the defendant’s new product, the purpose of the Present Invention can be achieved and identical function and effect can be obtained (satisfaction of the second requirement)…
[Regarding the third requirement for equivalence]
2. Overview and summary of court cases in which patent infringement under the doctrine of equivalents was affirmed
The number of cases in which patent infringement under the doctrine of equivalents was affirmed amounts to approximately 10% of the number of cases in which patent infringement under the doctrine of equivalents were alleged.
The cases in which patent infringement under the doctrine of equivalents was alleged were mostly filed and affirmed in the field of machinery, however, in the field of chemistry, patent infringement under the doctrine of equivalents has been affirmed by the court such as in the “Maxacalcitol” Case. Therefore, infringement under the doctrine of equivalents in the field of chemistry must be considered in the future.
As clearly understood from the “Spreader for Osteotomy” Case, the fifth requirement of the doctrine of equivalents may be found to be satisfied based on the constituent feature added by an amendment during prosecution of the patent application (similar decisions were made in the USA, Germany, and Italy).
The decision of this case is consistent with the recent cases in which patent infringement under the doctrine of equivalents was affirmed. Although there is nothing novel in the decision, we have highlighted this case because it is one of the few cases in which patent infringement under the doctrine of equivalents was affirmed.
Writer: Hideki TAKAISHI
Supervising editor: Kazuhiko YOSHIDA
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