“Friction Thermochromic Writing Instrument and Friction Heat Discoloration Set Using the Same”


The Intellectual Property High Court (IP High Court) overturned an appeal decision of invalidity rendered by the Japan Patent Office (JPO) regarding a patent having been corrected after issuance.


Legal Issue:

The legal issue concerns a friction-heat based thermochromic writing implement, and whether or not a person ordinarily skilled in the art would have been easily able to mount at the top of a cap, a friction body that is selected from elastomers and the like, in order to decolor handwritten ink by friction heat (identified as “difference 5″).

Summary of Conclusions:

In the appeal decision, the JPO looked to the cited reference 1, and determined that an elastomer or the like (cited reference 2) may be selected as a material for a friction body, and that it is a commonly used and well-known configuration to mount a friction body at the top of a cap. It was thus decided that the configuration of the cited reference 1, modified according to the “difference 5″ could have been easily achieved by those skilled in the art.

In contrast, the IP High Court held that the cited references 1 and 2 are significantly different from each other as to the configuration and function for handwriting, and that those skilled in the art would not combine the two references together. The IP High Court went on to say that the friction tool in cited reference 2 is separate from the writing tool, and therefore even if the cited references were combined, those skilled in the art would merely conceive of a writing tool according to the cited reference 1, and a separate friction tool provided with a friction portion, but not the configuration of cited reference 1 modified with the “difference 5″.  Accordingly, the IP High Court held that the configuration obtained by modifying cited reference 1 with the “difference 5″, could not be easily conceived”.

(Note) An English summary and provisional translation of the judgment by the Intellectual Property High Court is available here.


Even if those skilled in the art could have conceived of mounting a friction body on the cap of the writing tool, they may first conceive of combining the cited references 1 and 2 to provide “the friction body” together with the writing tool, and then, on the basis thereof, conceive of the feature of mounting a cap on the friction body as a means for providing the friction body, to achieve at last the configuration of the cited reference 1 modified according to the difference 5.  Accordingly, two steps are required to modify the cited reference 1 with the difference 5, in order to achieve the configuration of the claimed invention (accumulation of changes that may each be qualified as “easy”).  Therefore, a special effort is required, and those skilled in the art would not easily achieve the claimed invention.