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US 4,736,089 AGranted
Switching regulator for terminal printhead
AssigneeTexas Instruments Incorporated
InventorsVictor D. Hair, Mickey H. Everett
Life of this patent
Estimating the term…
Abstract
The thermal printhead of a printing terminal requires a controlled voltage to insure uniformity of the print copy. Printhead temperature is sensed by a voltage generating diode on the printhead itself. This feedback voltage is used to control the reference voltage of a switching regulator power supply which in turn provides power to the thermal printhead. The switching regulator comprises an efficient means of providing a controlled voltage to the thermal printhead.
Claims3
A printing terminal having means for providing a hard copy display, comprising:
- (a) thermal printing means;
- (b) temperature indicating means located to indicate the temperature of the thermal printing means;
- and
- (c) switching regulator power supply means for providing a controlled voltage to the thermal printing means, comprising:
- (i) switching means for operatively connecting a voltage source in circuit with the thermal printing means;
- (ii) means for establishing a preselected reference level in response to a signal from the temperature indicating means representative of the temperature of the thermal printing means,
- (iii) bi-stable means, coupled to the switching means having a first output state to close the switching means and a second output state to open the switching means;
- and
- (iv) control means connected to turn the bi-stable means on when the controlled voltage is less than the preselected reference level and to turn the bi-stable means off when the controlled voltage exceeds the preselected reference level, causing the first and second output states, respectively, to occur.
6 more elements
Dependencies are inferred from the claim text.