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Browse Prior Art Database

Printhead Assembly With Guide Bar

IP.com Disclosure Number: IPCOM000042691D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 81K

Publishing Venue

IBM

Related People

Oleksa, SA: AUTHOR

Abstract

The drawings show a thermal printer with lift-off correction, such as described in U.S. Patent 4,384,797, in which guide bar 1 is brought forward to accomplish correction. Nip rolls 3 and 5 feed ribbon 7 from a location past the printhead 9. Ribbon 7 is free to be pulled from a supply roll (not shown) on the opposite side of the print station. Guide bar 1 is spring-mounted on arm 11 to be held back (Fig. 2) by solenoid-controlled interposer 13 during printing. At the start of an erasure operation, guide bar 1 encounters platen 15 slightly before the end of printhead 9 encounters platen 15, thereby avoiding a stretching of ribbon which would occur if printhead 9 trapped the ribbon prior to movement of the guide bar 1.

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Printhead Assembly With Guide Bar

The drawings show a thermal printer with lift-off correction, such as described in U.S. Patent 4,384,797, in which guide bar 1 is brought forward to accomplish correction. Nip rolls 3 and 5 feed ribbon 7 from a location past the printhead 9. Ribbon 7 is free to be pulled from a supply roll (not shown) on the opposite side of the print station. Guide bar 1 is spring-mounted on arm 11 to be held back (Fig. 2) by solenoid-controlled interposer 13 during printing. At the start of an erasure operation, guide bar 1 encounters platen 15 slightly before the end of printhead 9 encounters platen 15, thereby avoiding a stretching of ribbon which would occur if printhead 9 trapped the ribbon prior to movement of the guide bar
1. Such stretching would occur because the ribbon is trapped at both the feed rolls and the printhead, while movement of the guide bar increases the path length which the ribbon occupies. The resulting forces may cause breakage of the ribbon or slippage of the ribbon under the printhead. Slippage under the printhead results in partial erasure or smear of ink from the ribbon. Printhead 9 is biased against a follower arm 17; printhead 9, arm 17 and arm 11 are pivoted at point 19. Arm 17 has a surface 21 which engages a cam surface (not shown) which is moved to position the printhead 9 and the guide bar 1. Printhead 9 carries a depending stud 23 which engages arm 17 to limit movement of printhead 9. The end of arm 17 near guide bar 1 mounts spring 25, the other end of whi...