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:
Nov. 14, 1989
Filed:
Nov. 16, 1987
Makoto Kurosawa, Ibaragi, JP;
Kenichi Igarashi, Ibaragi, JP;
Hitachi Koki Co., Ltd., Tokyo, JP;
Abstract
A dot matrix type printer head in which delays in the release of print hammers are eliminated by providing release coils only in alternate hammer positions, or alternatively, activating at one time only release coils in one of even-numbered and odd-numbered hammer positions. A rear yoke and a permanent magnet affixed to a lower leg of the rear yoke are provided in common for all hammer positions. An upper leg of the rear yoke is divided into a plurality of pole pieces. Hammer elements are provided having lower ends rigidly affixed to the rear yoke at positions adjacent the permanent magnet and upper ends retractable against pole faces of corresponding pole pieces by the magnetic force of the permanent magnet. In a first preferred embodiment of the invention, release coils are provided around only even-numbered or odd-numbered pole pieces. In a second preferred embodiment, release coils are provided around all pole pieces, but only release coils in even-numbered or odd-numbered hammer positions are driven simultaneously. In either case, stray magnetic flux which causes a delay in the release of a print hammer interposed between two previously activated print hammers is eliminated.