Mitsubishi Pencil Kabushiki Kaisha

Hiroyuki Mutou

Kazuaki Matsumoto

Seiichi Kobayashi

Takeshi Kobayashi

A writing implement for preventing ink from leaking out from a front end of a tip by absorbing much of a change in pressure inside an ink tank, the implement being a direct liquid type writing implement having an ink tank and an ink flowing portion connecting the ink tank and a writing end, a temporary ink reserve part for temporarily holding ink and an air supplying portion for supplying air to the temporary ink reserve part, the temporary ink reserve part being constituted by a temporary ink reserve groove and an ink guide groove, an ink introducing groove at a vicinity of the ink tank constituting a portion of the ink guide groove, a distance from the writing end to an end portion of the temporary ink reserve groove on its ink tank side being larger than a distance from the writing end to the ink introducing groove.

Writing implement

Basic configuration of a cap is as follows. When the end face of an elastic seal cylinder arranged in a cap for a writing instrument is caused to abut against and come into tight contact with the end portion of the mouth piece of a barrel cylinder to hermetically seal a point assembly and the opening portion of an air groove, first, the distal end of the point assembly is hermetically sealed with the bottom of the seal cylinder. The inner opening edge portion of the seal cylinder fits on the conical portion of an ink reservoir or of a point assembly support from an intermediate portion of the conical portion, and is gradually attached to the barrel cylinder while widening the opening portion of the seal cylinder in the radial direction. When the end face of the seal cylinder abuts against and comes into tight contact with the end portion of the mouth piece and attachment of the cap is completed, the end face of the seal cylinder and the end portion of the mouth piece are in tight contact with each other throughout the entire circumference.

Cap for writing instrument

A multiplex writing implement of the invention has a multiple number of writing elements, including at least one ball-point pen element which is filled up with a thixotropic water-soluble or low-viscosity oil-based ball-point ink. The ink reserving portion of the ink reservoir of the ball-point pen element is non-flexible and has a relatively large cross-section. A portion for jointing the point assembly with the ink reserving portion is formed so that the element can readily be deflected transversely with respect to the axial direction. The writing tip portions of these writing elements can selectively be projected from and retracted into the barrel front. This multiplex writing implement is able to create line traces with thick line density without causing any blobbing of ink or ink starving. It is also possible to prevent accidental ink leakage. That is, ink can be prevented from staining the barrel cylinder, user's hands, clothes etc., which would be caused by forward leakage of ink or back leakage of ink due to upward writing as well as due to impacts from being dropped or clicked. Still, the multiplex writing implement has a suitable barrel size which meets the demands for portability and high performances of handling.

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Yokohama, Japan

Hiroyuki Mutou