US 4,904,098 AGranted

Flexible print ribbon shield

AssigneeUnisys Corporation

InventorThomas A. Hamilton

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Abstract

A print wheel impact printer in a document encoder comprises a flexible shield (38) made from laminar polyester sheet, the shield (38) having a shielding portion (40) at either end of which is provided a folded portion (44), each folded portion (44) being operative by virtue of non-90 degree fold lines and by virtue of the folds (50,52) forming at least three sides of a polyhedron to support the flexible shielding section distant from the print wheel (14). The shielding portion (44) is maintained tilted relative to the line between the hammer (26) and the print wheel (14) thereby to provide an opening (68) wherethrough the ink ribbon may be passed when an ink ribbon cassette (10) is changed. In operation the flexible shielding portion (40) is moved and carried by the paper (30), driven by the hammer (26), against the ink ribbon (12) and print wheel (14) with the paper (30) protruding through an aperture (42) in the shielding portion (40). Extraneous marking or blemishes created on the paper by contact with the ribbon (12) are thereby avoided.

Claims9

Dependent claims

An impact printer for printing on a presented document, said printer comprising:

a hammer operative when in use to push the document against an ink ribbon and for the ink ribbon to be pushed in turn against a rotatable print surface to leave a record of a selected character upon the document;
a shield disposed between the document and the ink ribbon to prevent contact other than when said hammer is in operation, said shield including a shielding portion having opposite extremities along its longitudinal axis, said shielding portion having at least one hole-like aperture and first and second folded portions integral respectively with said opposite extremities, said first and second folded portions being displaced relative to said shielding portion so that said shielding portion is disposed at an offset angle relative to the plane which lies at 90 degrees to the direction of approach of said hammer towards said print surface when said shield is mounted in its operative position in said impact printer by said first and second folded portions;
said shield being flexible and, when said document is pushed towards said ink ribbon by said hammer via said aperture, said shield moving under pressure from the document towards said print surface to allow contact between the document and said ink ribbon.

Dependencies are inferred from the claim text.