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Constant Current Driver Multiplexing Scheme for Electrothermal Printing

IP.com Disclosure Number: IPCOM000051460D
Original Publication Date: 1981-Jan-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Findlay, RG: AUTHOR

Abstract

A circuit is described for driving a print head which permits a limited number of constant current drivers to be shared among a large number of print electrodes.

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Constant Current Driver Multiplexing Scheme for Electrothermal Printing

A circuit is described for driving a print head which permits a limited number of constant current drivers to be shared among a large number of print electrodes.

In the circuit N different print groups share M constant current driver circuits
10. An M-bit data shift register 12 is provided, and each of the N groups of M bits of data is shifted in turn into shift register 12. Each bit of the data in shift register 12 is coupled to control one of the constant current drivers 10. Each of the constant current driver outputs is connected to the power supply terminal of a driver circuit 14. So long as only one input to each of the driver circuit 14 chip groups is active at any given time, essentially all the input current to the driver chip group is directed to the one active input, thereby providing a means of steering the constant current to any one of N outputs.

To ensure that only one input of each driver group is active at one time, the driver group inputs 16 1-n are driven from the outputs 18 1-n of a 1 of N decoder circuit 20, in which only one output at a time is active.

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