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Thermal Simulation in a Wire-Matrix Printer to Indicate Head Temperature

IP.com Disclosure Number: IPCOM000042953D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Frankeny, RF: AUTHOR

Abstract

Excessive heat in a wire-matrix printhead can cause serious damage. This article describes a thermal simulation circuit for outputting an analog signal proportional to the average energy delivered to the actuator of a particular wire in such a matrix printhead. With feedback effected via a comparator system incorporating responsiveness to ambient temperature, the resultant process enables the system to stimulate corrective action when printhead use exceeds the design duty cycle. This circuit (see illustration) provides a means whereby the wire fire pulse triggers the generation of an analog signal proportional to the average energy delivered to the actuator.

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Thermal Simulation in a Wire-Matrix Printer to Indicate Head Temperature

Excessive heat in a wire-matrix printhead can cause serious damage. This article describes a thermal simulation circuit for outputting an analog signal proportional to the average energy delivered to the actuator of a particular wire in such a matrix printhead. With feedback effected via a comparator system incorporating responsiveness to ambient temperature, the resultant process enables the system to stimulate corrective action when printhead use exceeds the design duty cycle. This circuit (see illustration) provides a means whereby the wire fire pulse triggers the generation of an analog signal proportional to the average energy delivered to the actuator. Through the provision of a temperature-varying threshold, this signal can be compared in such a way as to provide the controlling system a feedback signal when the head duty cycle at a given temperature is exceeded. Since the majority of the energy delivered to the actuator is dissipated as heat, a capacitor (C) charged by a pulsed current source functions as an accurate analog of the thermal process. When energy is not being delivered, current discharge of C through resistance Rc represents the transfer of thermal energy from the printhead. Each time the controlling system triggers a wire fire, a single-shot (SS) emits a fixed pulse of width t. This pulse then gates out a current pulse of amplitude I and width t, and a step in voltage V...