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Browse Prior Art Database

Ribbon Drive Apparatus for Printer

IP.com Disclosure Number: IPCOM000052493D
Original Publication Date: 1981-Jun-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 3 page(s) / 45K

Publishing Venue

IBM

Related People

Baker, GN: AUTHOR [+4]

Abstract

This apparatus provides (1) ribbon reversal without the need of sensing devices and (2) improved ribbon tracking that is less dependent on tolerance factors. Ribbon reversal in a reel-to-reel ribbon drive is accomplished without using sensing arms or switches. Most reel-to-reel drives employ a grommet or similar device near the end of the ribbon which actuates a switch or mechanical reversing mechanism. Such devices may have operational difficulties and threading of the ribbon is usually complicated. In the apparatus shown in the drawing, stepper motors are used and electrical ribbon reversal circuitry so that no switches, grommets, or sensing arms are required. As one stepper motor is driving the ribbon, the other motor is used as an emitter or pulse generator.

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Ribbon Drive Apparatus for Printer

This apparatus provides (1) ribbon reversal without the need of sensing devices and (2) improved ribbon tracking that is less dependent on tolerance factors. Ribbon reversal in a reel-to-reel ribbon drive is accomplished without using sensing arms or switches. Most reel-to-reel drives employ a grommet or similar device near the end of the ribbon which actuates a switch or mechanical reversing mechanism. Such devices may have operational difficulties and threading of the ribbon is usually complicated. In the apparatus shown in the drawing, stepper motors are used and electrical ribbon reversal circuitry so that no switches, grommets, or sensing arms are required. As one stepper motor is driving the ribbon, the other motor is used as an emitter or pulse generator. Each motor contains permanent magnets and field coils and thus generates electrical pulses as it is driven. These pulses are sensed and shaped so they can be logically detected. The logic counts both the stepper pulses sent to the driving motor and the emitter pulses received from the driven motor.

Considering the drawing more specifically, the apparatus includes left and right-hand spools 1 and 2 accommodating a ribbon 3 with each spool being driven by a respectively associated motor 4 or 5. Motor drive circuits 7 and 8 supply driving signals.

When one motor is driven, the other motor is dragged, generating emitter signals. For example, when left motor 4 is driven as a result of activation of line 9a from control block 10, then the emitter sense circuit 11 for right motor 5 is gated by way of line 9b so that motor 5 emitter pulses are made available through Or circuit 12 to the End of Ribbon/Jam block 13. A similar sequence occurs when right motor 5 is driven due to lines 14a and 14b becoming active but this time motor 4 is dragged and emitter sense circuit 15 is active in conjunction with Or circuit 12 and block 13.

Thus, the roles of the motors are continuously reversed. The driver motor becomes the emitter motor, and vice versa by appropriate switching of the control circuitry. Emitter-derived pulses are directed from block 13 by way of line 16 to Control block 10 and a Ribbon Length counter 17 which in turn drives a Short Ribbon counter 18 that supplies an error signal by line 19 to a printer controller, not shown.

If an emitter pulse is not received from block 13 during a predetermined number of driver pulses from block 10, either the ribbon has reached the end or there is a ribbon jam. In any case, the ribbon is reversed. If no ribbon jam exists, the direction of ribbon motion continues to the other end of the ribbon.

Ribbon Length counter 17 keeps track of the number...