Osaka District Court, Heisei 21 (Wa) 10811 [Method and Apparatus for Manufacturing a Rotary Toothbrush]
Updated: 1 hour ago
Article information
Type: Case note
Classification: Patents
Topics: Damages
First published on this site: 2023-12-07
Case number: Heisei 21 (Wa) 10811
Display and classification checked: 2026-11-14
Osaka District Court, Heisei 21 (Wa) 10811 [Method and Apparatus for Manufacturing a Rotary Toothbrush]
<Damages> Article 102(1)
Contribution rate 10% (90% rebutted)
Circumstances preventing sales: 80%
<Grounds for rebutting the presumption> Proviso to Article 102(1)
(1) Trading relationships with numerous retailers
(2) Advertising activities
(3) Price difference
<Contribution rate>
Merely advanced the manufacturing method on the premise of a product invention
<Grounds for rebutting the presumption> Proviso to Article 102(1): circumstances under which the plaintiff would have been unable to sell its product
The defendant can be said to have achieved that sales volume by setting a suggested retail price of JPY 500, maintaining relationships with numerous retailers, and combining these with advertising activities involving substantial expenditure.
Sales of the plaintiff's product peaked in Heisei 15 and 16, declined in Heisei 17–18, and by the latter year the business was showing signs of reaching an impasse.
There are structural differences: the cylindrical brush is rotatably mounted in the plaintiff's product, whereas in the defendant's product it is fixed to the brush handle.
Price difference: the defendant's suggested retail price is JPY 500; the plaintiff's retail price is JPY 1,500–3,000, considerably high for a toothbrush.
<Contribution rate>
The greatest feature of the plaintiff's product is that a rotary brush formed by stacking numerous individual brush discs is rotatably attached to the handle member. The effects of this structure, including plaque removal and prevention or improvement of periodontal disease through gum massage, as well as the aesthetic appeal of its form, distinct from ordinary toothbrushes, can be said to stimulate demand among consumers.
⇒ What the defendant infringed, however, was a patent right for inventions of methods and apparatuses for efficiently manufacturing such rotary brushes and individual brush discs without skilled techniques, and
the method invention is positioned merely as advancing the manufacturing method on the premise of a product invention. ⇒ A contribution rate of 10% for the invention is appropriate.
(Extract from the court's reasoning)
Grounds for rebuttal
Over approximately four years from November 9, Heisei 19, the defendant transferred ●●●●●●●●●●●●●●●●●●●●●●● of its products. It can be said to have achieved that sales volume by setting a suggested retail price of JPY 500 (Ko 27-2 and 27-3), maintaining trading relationships with numerous retailers (Ko 33 and 34), and combining these with advertising activities involving substantial expenditure (Ko 9; Ko 27-1 to 27-3; entire purport of the oral argument).
By contrast, the plaintiff's product had been manufactured and sold by TC Dental, whose representative director is plaintiff P1, before plaintiff T World was established on November 9, Heisei 19 and granted the contractually exclusive ordinary license at issue. From that date onward, only plaintiff T World manufactured and sold it. The combined sales volumes of the two companies were approximately as follows (Ko 55). (Passage omitted in source)
Namely, sales of the plaintiff's product peaked at approximately ●●● units in Heisei 15 and approximately ●●● units in Heisei 16, and by Heisei 17–18 had already fallen to the ●●-unit range per year; in the latter year the business was showing signs of reaching an impasse (Ko 56). Moreover, since November 9, Heisei 19, when the contractually exclusive ordinary license was granted (or, indeed, since July 6 of that year, when the patent right was registered), the plaintiff's product has not been sold in retail stores (Ko 56; entire purport of the oral argument). Although TC Dental had previously advertised it (Ko 23 and 53), there is insufficient evidence of prominent advertising such as television commercials or magazine placements after that time, apart from its own website (plaintiff T World itself admits that no advertising expenses were incurred for its product).
Although the plaintiff's and defendant's products both have cylindrical brushes, they differ structurally: the plaintiff's brush is rotatably mounted, whereas the defendant's is fixed to the handle (Ko 23–25, 27-1 to 27-3, 28, 31 and 32). Moreover, although specific sales volumes are unknown, similar products can be found both among toothbrushes with rotatably mounted cylindrical brush portions like the plaintiff's product and among toothbrushes with cylindrical brush portions fixed to the handle like the defendant's product (Otsu 56–68). It is therefore difficult to find that all customers would have purchased the plaintiff's product had the defendant's product not been sold.
In addition, the plaintiff's retail price was JPY 3,000 when TC Dental sold it and JPY 1,500 even under plaintiff T World, considerably high for a toothbrush. This point alone makes it doubtful whether the same number as the defendant's product could have been sold. Plaintiff P1 himself states that the plan was ‘●●●●●●●●●●●●●●●●’ (Ko 56). Thus, insofar as the damages claim assumes a high price in calculating profit per unit of the plaintiff's product, it can be said that the plaintiff should accept a finding of a smaller number that could have been sold.
In view of the foregoing, since November 9, Heisei 19, when plaintiff T World obtained the contractually exclusive ordinary license, even absent the defendant's infringement of that license, there were necessarily circumstances under which the plaintiff's product could not have achieved the same volume of ●●●●●●●● units as the defendant's product. It is appropriate to find the quantity deductible for these circumstances to be ●●●●●●●● units, equivalent to 80% of the defendant's transferred quantity of ●●●●●●●● units.
Contribution rate
In examining the contribution of the patented method invention to the plaintiff's profits from its product, as plaintiff T World itself emphasizes, the product's greatest feature is that a rotary brush formed by stacking numerous individual brush discs is rotatably attached to the handle member. The effects of that structure, including plaque removal and prevention or improvement of periodontal disease through gum massage, as well as the aesthetic appeal of its form, distinct from ordinary toothbrushes, can be said to stimulate demand among consumers. However, what the defendant infringed here was the patent right for inventions of methods and apparatuses for efficiently manufacturing such rotary brushes and individual brush discs without skilled techniques; these do not directly concern the functions of the rotary brush or individual brush discs. The plaintiff's product itself is an embodiment of an invention for which plaintiff P1 separately applied for a patent (Japanese Patent Application Heisei 12-83736; Exhibit Hei (丙) 17 within Otsu 45-1; the evidence does not establish whether a decision to grant was issued). The patented method invention at issue is positioned merely as advancing the manufacturing method on the premise of that product invention. The plaintiff also registered a design for the form of its product described above (Ko 47), and the registered design is expressly identified on the product's packaging (Ko 11). As stated above, while the packaging identifies another patent entitled ‘Roll Toothbrush’ (Ko 45), it does not identify the patent at issue.
Viewed in this way, the patented method invention can be said to make a certain contribution to profits from the plaintiff's product as technology for manufacturing the individual brush discs that constitute the rotary brush, the principal part of the product, ‘efficiently, without requiring a high degree of skill and with as few steps as possible’ compared with prior art (Ko 2). Nevertheless, its contribution must be regarded as considerably lower than the contribution of the plaintiff's product itself, namely its structural features, effects, and the aesthetic appeal of its form.
Accordingly, it is appropriate to find the contribution rate of the patented method invention to be 10%.
Originally published: 2023-12-07
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Update history
The first publication date and update dates are recorded separately. Display maintenance does not mean that the legal analysis was re-verified.
2026-11-14: Display and classification maintenance (article information, issue tags, language/SEO links, related articles, and consultation path added).
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