The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 25, 2002
Filed:
Jan. 26, 2001
Applicant:
Inventor:
Takao Koyama, Ashikaga, JP;
Assignee:
Mitsubishi Pencil Kabushiki Kaisha, Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
B43K 5/00 ; A45D 3/400 ;
U.S. Cl.
CPC ...
B43K 5/00 ; A45D 3/400 ;
Abstract
Provided is a free ink type writing instrument having an ink tank part for storing an ink, in which an amount of the ink can visually be observed. The free ink type writing instrument is characterized by that the whole or a part of an internal surface part in contact with the ink in the ink tank part has a smaller critical surface tension than a surface tension of the ink, and a contact angle between the ink and the whole or a part of the internal surface part in contact with the ink in the ink tank part is 30° or more at a temperature of 25° C.