Tokyo District Court, 2022 (Wa) 70058 [Grapple Bucket Device] <Kokubu>
Updated: 6 hours ago
Article information
Article type: Case note
Category: Patents
Topics: Doctrine of equivalents
First published on this website: 2026-11-01
Display and classification checked: November 2, 2026
Originally published on Ameblo: 2025-07-11 (Japan time). Full English translation.
Tokyo District Court, 2022 (Wa) 70058 [Grapple Bucket Device] <Kokubu>
First requirement of the doctrine of equivalents: not satisfied.
*The analytical framework of the IP High Court Grand Panel judgment in the Maxacalcitol case.
⇒ A defendant seeking to defeat the first requirement of the doctrine of equivalents should confront the invention at issue with closely related prior art, argue that the problem described in the specification at issue is insufficiently stated, and steer the argument toward the proposition that the difference from that prior art is the essential part.
*The problem described in the specification at issue could be solved by the prior art.
⇒ The description of the problem is objectively insufficient in light of the prior art at the filing date, so extrinsic evidence may be considered.
⇒ The degree of the invention's contribution cannot be assessed as substantial.
⇒ The essential part of the invention cannot be identified at a higher level of abstraction, and is identified as substantially equivalent to the language of the claims.
⇒ The difference from the prior art is the essential part.
(Excerpt from the court's reasoning)
At the time the patent at issue was filed, the problem that, when timber gripped by a grapple bucket device was long, a worker had to use a cutting device such as a chainsaw to cut timber exceeding a certain length to a prescribed length could be solved by the prior art disclosed in the Exhibit Ko 27 reference. Thus, the problem described in the specification at issue as one that the prior art could not solve is found to be objectively insufficient in light of the prior art at the filing date. Accordingly, when identifying the characteristic part constituting the technical idea peculiar to the invention at issue and absent from the prior art, consideration of the technical matters described in the Exhibit Ko 27 reference should also be permitted.
… Before the patent at issue was filed, the Exhibit Ko 27 reference is found to have disclosed a traveling branch-cutting apparatus equipped with a bucket having a gripping unit attached to one side and a cutting device attached to the other. The difference between the invention at issue and the prior art is therefore found to lie only in the configuration of that cutting device, not in the fact that the device itself is a grapple bucket device capable of cutting material that it has gripped. Accordingly, because the degree of the invention's contribution relative to the prior art cannot be assessed as substantial, its essential part cannot be identified at a higher level of abstraction, and should be identified as substantially equivalent to the language of the claims.
Therefore, … it is appropriate to find that the characteristic part constituting the technical idea peculiar to the invention at issue and absent from the prior art is the adoption, for the cutting device provided on the grapple device, of the following configuration: a cutting blade located on either the outside or the inside of the bucket's side wall, pivoting in a direction along that side wall from a position away from the bucket's opening edge to a position along the bucket's side wall, and having a cutting edge on its side edge facing the opening-edge side of the bucket, pivoting in a direction along the side wall to a position along the bucket's side wall, and having a cutting edge on its side edge facing the opening-edge side of the bucket, the blade being pivotally supported at the base of the bucket opening; and a hydraulic cylinder connected to the pivot base of that cutting blade to pivot the blade. The cutting edge of the cutting blade is positioned offset toward the blade's cutting direction relative to the line connecting the blade's pivot center and the hydraulic-cylinder connection point, and is curved in an arc backward relative to its direction of rotation in the cutting direction. By adopting this configuration, namely the configuration relating to constituent requirements C and D, a large value of the inclination angle θ at which the blade edge contacts the object is maintained even in portions far from the pivot center, thereby maintaining a draw-cutting action and achieving a smooth cutting effect.
… The essential part of the invention at issue is that, by adopting the configuration relating to constituent requirements C and D, a large value of the inclination angle θ at which the blade edge contacts the object is maintained even in portions far from the pivot center, thereby maintaining a draw-cutting action and achieving a smooth cutting effect. Consequently, the defendant's products cannot be found to possess the essential part of the invention at issue, and it cannot be said that the part in which the invention and the defendant's products differ is not the essential part of the invention.
Translator’s notes (editorial)
The quoted source contains missing characters in the final long technical paragraph and repeats the phrase describing rotation along the side wall and the facing cutting edge. The repetition is retained in English; the missing connecting text is rendered according to the surrounding syntax, without altering the technical elements.
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Update history
The first-published date remains unchanged. Display maintenance, classification changes, related-article updates, and text corrections are recorded separately.
November 1, 2026: First published on this website.
November 2, 2026: Added article information, classification, topics, language navigation, related articles where the same case was confirmed, consultation guidance, and SEO. The original text and first-published date were preserved.
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