US 4,883,375 AGranted

Printing device

AssigneeBrother Kogyo Kabushiki Kaisha

InventorsYoshiyuki Karube, Yuji Kawahara

Life of this patent

Estimating the term…

Loading patent…

Abstract

A guide shaft guides a print head, which moves along a print line of a platen to perform a printing operation. A rotating member and an eccentric cam member, having a toothed sector portion on its periphery, are mounted on the guide shaft. The guide shaft is guided on a frame by a bearing slot, so as to be movable toward and away from the platen. The eccentric cam member rotates as it is always spring-urged to engage a fixed engaging pin. As a result, the guide shaft moves in a direction transverse to its axis, thus changing a gap between the print head and the platen. As the eccentric cam member rotates in one direction, the print head moves away from the platen, in a retreat stroke. In a rear half of the retreat stroke, the toothed sector portion of the rotating member engages a toothed arm, which is connected to a paper bail member for holding a printing medium down on the platen. Thus, as the gap between the print head and the platen is widened, the paper bail member moves from a medium hold position and a release position off the platen.

In a printing device including a frame, a platen wound, on its peripheral surface, with a printing medium, a print head which defines a gap between the print head the the platen and is movable parallel to the platen, along a print line of the platen, so that the printing medium is printed as the print head moves, and medium holding means movable between a hold position in which the holding means holds the printing medium down on the platen, and a release position in which the holding means is off the platen, said printing device comprising:

drive means for moving the print head back and forth in a transverse direction, with respect to the print line of the platen, said drive means having an advance stroke, in which the print head is moved toward the platen, and retreat stroke, in which the print head is moved away from the platen;
and
operative-transmission means operative for operatively connecting the drive means and the medium holding means so that the medium holding means is moved from the hold position to the release position, wherein:
said retreat stroke of said drive means including, at the start of the retreat stroke, a first stroke portion in which operation of said operative-transmission means is disabled and, subsequent to the first stroke portion, a second stroke portion in which operation of said operative-transmission means is enabled;
said first stroke portion being allowed to an adjustment operation of said gap for regulating printing condition by said print head on the printing medium, thereby causing said adjustment operation of said gap to be done independently of the operation of said operative-transmission means;
said drive means includes a single reversible electric motor, adapted to provide the advance stroke by rotating in one direction, and to provide the retreat stroke by rotating in the other direction, said motor being stopped at the end position of the advance stroke and then rotating reversely, thus starting the first stroke portion of the retreat stroke;
and
said gap adjustment operation being continued during said first stroke portion until said gap has a predetermined width.

5 more elements

Facts

Application

07/338,390Filed 12 Apr 1989 · continuation

Priority

JP 60-21435926 Sep 1985

Granted

28 Nov 1989

Term ends

Not estimatedThe source records don’t support an estimate.

Classification4 codes

B41J 25/304
Actions or mechanisms not otherwise provided for: bodily-movable mechanisms for print heads or carriages movable towards or from paper surface
B41J 13/10
Devices or arrangements of selective printing mechanisms, e.g. ink-jet printers or thermal printers, specially adapted for supporting or…
B41J 13/20
Sheet holders, retainers , movable guides, or stationary guides: bails
B41J
Typewriters

Abstract

Claims8