In this case, the Plaintiff brought a law suit seeking an injunction against the Defendants to stop them from importing and selling their products and to demand compensation for damages. The Plaintiff argued the import and sale was an infringement of its patent which is directed to an invention related to a chair with swing function ("Invention") under the doctrine of equivalents ("DOE"). The IP High Court ("IPHC") dismissed the appeal on the grounds that the first and fifth requirements of the DOE were not satisfied. The judgment on the first requirement of the DOE is explained below.
The Invention is a chair for infants with an automatic swing function ("Swing Chair") adopting a solenoid actuator as the swing control system and a method using pendulous rods set at (at least) two points along the swing direction to hold the seat ("Two Rods Holding Method"). The patent specification describes an invention of a Swing Chair adopting a solenoid actuator as the swing control system and a method using a pendulous rod set at one point along the swing direction to hold the seat ("One Rod Holding Method") as a prior art. The problem with this prior art is that the rotational moment is increased by the deviation of the centroid when an infant sits near the edge of the seat, which is to be solved by the Invention adopting the Two Rods Holding Method.
The accused product is a Swing Chair adopting a solenoid actuator as the swing control system and a method using wheels set at two points along the swing direction under the seat to hold the seat. In other words, the accused product does not adopt the Two Rods Holding Method but has two swingable points holding the seat in common with the Invention. In connection with such difference between the accused product and the Invention, one of the primary issues was whether the accused product constitutes an infringement under the DOE.
As for the 'essential part of an invention' under the first requirement of the DOE, the IPHC presented the following standards, which are the same with the standards presented in the previous judgment of the IP High Court's Grand Panel (Intellectual Property High Court, June 29, 2016) ("Grand Panel Judgment") (please refer to our Japan IP Enforcement & Transactions Newsletter Vol. 1 (April 2016)):
- The essential part of an invention shall mean the characteristic part constituting the unique technical idea non-existent in the prior art, in the description in the patent claim. If the degree of contribution by an invention is high when compared to the prior art, the essential part is to be identified as the superordinate concept of a part of the patent claim of the invention. On the other hand, if the degree of contribution by an invention is not so high, the essential part is to be identified as almost the same thing as described in the patent claim of the invention.
- Besides, if what is described as the previously unsolved problem in the patent specification is objectively insufficient in the light of the prior art at the time of the patent application, the characteristic part of the invention shall be identified taking account of the prior art not described in the patent specification as well. In such case, the essential part of an invention shall be closer to the description of the patent claim as such and the scope where an infringement under the DOE is found shall become narrower, as compared to the case where the essential part of an invention is to be identified only based on the patent claim and specification of the invention. The IPHC held that adopting the Two Rods Holding Method in the Swing Chair is well-known art and that the description of the patent specification is objectively insufficient in light of the prior art. Further, the IPHC stated that the essential part of the Invention must be identified based on a comparison with the above well-known art as the prior art at the priority date as well as the description of the patent specification. Based on the above, the IPHC assessed that the degree of contribution by the Invention, which only adopts a Two Rods Holding Method instead of the One Rod Holding Method, is not so high and identified that the adoption of the Two Rods Holding Method in the Swing Chair with solenoid actuator as the essential part of the Invention. Although the Appellant argued that the adopting two swingable points holding the seat was the essential part of the Invention, the IPHC rejected this argument stating that it ignores the rods which are a component of the Two Rods Holding Method. Based on the above, the IPHC concluded that the first requirement of the DOE was not satisfied.
This case would provide a useful guideline as to such circumstances where the essential part of an invention shall be identified by taking account of the prior art not described in the patent specification in terms of the firs requirement of the DOE.
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