Patents by Inventor Masa-aki Sumi-i

Masa-aki Sumi-i has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Writing set
    Patent number: 4748147
    Abstract: A writing set comprising a combination of paper printed thereon with two or more coloring bands using two or more types of leuco dye which develop different colors and a writing means which contains a solution of acid materials which develops the color of the leuco dyes.When characters, pictures, etc. are written on the paper, the colorless leuco dyes in the written portion develop color to form colorful characters, pictures, etc.
    Type: Grant
    Filed: November 29, 1985
    Date of Patent: May 31, 1988
    Assignee: Sakura Color Products Corp.
    Inventors: Masa-aki Sumi-i, Hikoshiro Nushimura