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Self Adjusting Printhead

IP.com Disclosure Number: IPCOM000045406D
Original Publication Date: 1983-Mar-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Kluvo, KG: AUTHOR [+2]

Abstract

The gap between the form and the printhead on a wire matrix printer is a critical dimension. If this distance is too small, the printhead and ribbon rub against the form, causing an ink smudge. If the distance is too large, the printhead will be unable to fire the wires far enough to cause a dot or character to be printed on the form. The common solution to this problem is to make the printhead user adjustable so that for the thin forms, the printhead is moved closer to the platen, and for thicker form it is moved further away. The user must go through this process for each different form thickness that is used in the printer.

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Self Adjusting Printhead

The gap between the form and the printhead on a wire matrix printer is a critical dimension. If this distance is too small, the printhead and ribbon rub against the form, causing an ink smudge. If the distance is too large, the printhead will be unable to fire the wires far enough to cause a dot or character to be printed on the form. The common solution to this problem is to make the printhead user adjustable so that for the thin forms, the printhead is moved closer to the platen, and for thicker form it is moved further away. The user must go through this process for each different form thickness that is used in the printer.

Referring to the figure, a printer which automatically gauges the thickness of the form and sets the print gap is shown. The print gap 12 is the distance between the end of the printhead 10 and the form 18. The printhead 10 is rigidly mounted to a carrier, thereby eliminating the operator adjustment capability. The print gap 12 is obtained by the movement of the platen 14 which is actuated by the gauge rolls 16 sensing the form 18 thickness. The movement of the gauge rolls 16 is transmitted on a 1:1 ratio lever arm 20 about the pivot point 22 to the platen 14. Therefore, if the gauge rolls 16 move a given distance, the platen 14 is also moved a corresponding distance in the opposite direction.

The idler rolls 24 rotate about a fixed point and are spring-loaded by spring 26 at both ends of the print line to the gauge...