Browse Prior Art Database

Shifting Gear Anti-Reverse Mechanism

IP.com Disclosure Number: IPCOM000059947D
Original Publication Date: 1986-Feb-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 78K

Publishing Venue

IBM

Related People

Robinson, CW: AUTHOR [+2]

Abstract

An idler gear, with its shaft running in a slot-shaped journal, when urged by attempted reverse rotation of a mating gear, shifts its position and engages a detent which prevents reverse rotation. Fig. 1 shows this anti-reverse mechanism embodied in printer ribbon cartridge 1. It is seen that integral to cartridge 1 is a ribbon take-up shaft that includes external knob 2 and combination gear 3, which engages idler gear 4. Detent 5, molded into cartridge 1, is adjacent to gear 4. The ribbon drive mechanism, external to cartridge 1, includes bidirectional drive shaft 6, unidirectional clutch 7, and drive gears 8 and 9. Gear 9 is a combination spur/bevel gear that mates with a bevel on combination gear 3 that extends outside cartridge 1.

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Shifting Gear Anti-Reverse Mechanism

An idler gear, with its shaft running in a slot-shaped journal, when urged by attempted reverse rotation of a mating gear, shifts its position and engages a detent which prevents reverse rotation. Fig. 1 shows this anti-reverse mechanism embodied in printer ribbon cartridge 1. It is seen that integral to cartridge 1 is a ribbon take-up shaft that includes external knob 2 and combination gear 3, which engages idler gear 4. Detent 5, molded into cartridge 1, is adjacent to gear 4. The ribbon drive mechanism, external to cartridge 1, includes bidirectional drive shaft 6, unidirectional clutch 7, and drive gears 8 and 9. Gear 9 is a combination spur/bevel gear that mates with a bevel on combination gear 3 that extends outside cartridge 1. Self-actuated unidirectional spring clutch 7 is designed to transfer torque from bidirectional shaft 6 to the gear train, driving gears 8, 9, and 3 in the directions shown. Although ideally there is no torque transfer in the reverse direction, most such clutches inherently require some small amount of reverse torque to induce them to de-clutch and remain de-clutched. In the embodiment shown this small overrunning torque is multiplied by the gear train and has a tendency to drive gear 3, on the ribbon take-up shaft, in the reverse direction. Such reverse rotation, if not prevented, causes the ribbon to become loose and jam. Referring to Figs. 2 and 3, it is seen that by virtue of a its slot- shape...