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Print Band Height Control Servo

IP.com Disclosure Number: IPCOM000060960D
Original Publication Date: 1986-Jun-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Melnyk, G: AUTHOR

Abstract

The servo control for maintaining a selected print band height can be made less sensitive to height variations by requiring a predetermined count accumulation before permitting servo response to an out-of-limit condition. Referring to Figs. 1 and 2, endless print band 1 is constantly driven on flat drive and crowned idler pulleys (not shown) and passes through transducer 2 that senses the height of the lower edge of the band. A reversible motor is connected to the idler pulley shaft to adjust the pulley height and, hence, the band. Transducer 2, which may be a magnetic sensor, provides an analog output signal to sensor circuit 3 that energizes line A or B, indicating that the band is either too high or too low, respectively.

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Print Band Height Control Servo

The servo control for maintaining a selected print band height can be made less sensitive to height variations by requiring a predetermined count accumulation before permitting servo response to an out-of-limit condition. Referring to Figs. 1 and 2, endless print band 1 is constantly driven on flat drive and crowned idler pulleys (not shown) and passes through transducer 2 that senses the height of the lower edge of the band. A reversible motor is connected to the idler pulley shaft to adjust the pulley height and, hence, the band. Transducer 2, which may be a magnetic sensor, provides an analog output signal to sensor circuit 3 that energizes line A or B, indicating that the band is either too high or too low, respectively. If the height adjustment motor were directly responsive to energization of lines A or B, continuous hunting and adjustment would occur. Servo hunting is avoided by connecting lines A and B to condition a respective AND gate 4, 5, when energized, and pass pulses from oscillator 6 to up-down counter 7. Counter 7 is non-wrapping and is arranged to provide a carry signal whenever it reaches maximum count and to provide a borrow signal when at its minimum count. The carry signal sets latch 8 to energize the idler pulley adjustment motor circuits 9 and lower the idler pulley and band, and the borrow signal sets latch 10 to reverse the motor to raise the idler pulley. Latches 8 and 10 are cleared by an oscillator puls...