US 4,791,435 AGranted

Thermal inkjet printhead temperature control

AssigneeHewlett-Packard Company

InventorsJames C. Smith, Hatem E. Mostafa, William J. Walsh

Life of this patent

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Abstract

Thermal inkjet printhead temperature control is provided in a temperature control system responsive to printhead temperature, which in the presence of printhead overheating selectively causes the printhead to stand idle, or, if multiple nozzles are available, shifts to a nozzle which, is not overheated, which in the event a nozzle is unused for some time and the dye transport agent may have evaporated leaving a viscous plug in the nozzle, employs warm up pulsing and/or nozzle spitting to clear the nozzles, and which when the temperatures of the nozzle is below acceptable printing temperatures, employs nozzle pulsing for warm up and/or nozzle spitting to clear the nozzles, all such decisions and actions being provided in advance of beginning a printing operation.

Claims4

Dependent claims

A temperature control system for a thermal inkjet printer, having a printer carriage drive, a printer carriage movable by said printer carriage drive across a printing zone between sweep limit positions and movable to and from a rest position in response to print commands, and having a thermal inkjet printhead mounted on said carriage, comprising:

control means including said printer carriage drive and including print drive circuits coupled to said thermal inkjet printhead and responsive to the position of said printer carriage being driven by said printer carriage drive, for producing electrical pulses for firing inkdrops from said thermal inkjet printhead in said printing zone and for stopping said electrical pulses outside of said printing zone;
temperature sensor means for sensing the temperature of said thermal inkjet printhead;
and
means responsive to said temperature sensor means for controlling said printer carriage drive of said control means to reduce printer carriage speed above a predetermined sensed temperature, to permit said printhead to cool and thereby to maintain the temperature of said thermal inkjet printhead substantially at said predetermined temperature.

1 more element

Dependencies are inferred from the claim text.

Facts

Application: 07/077,552Filed 23 Jul 1987
Granted: 13 Dec 1988
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

B41J 2/04515
Control methods or devices therefor, e.g. driver circuits, control circuits: preventing overheating
B41J 2/04528
Control methods or devices therefor, e.g. driver circuits, control circuits: aiming at warming up the head
B41J 2/04563
Control methods or devices therefor, e.g. driver circuits, control circuits: detecting head temperature; Ink temperature
B41J 2/0458
Control methods or devices therefor, e.g. driver circuits, control circuits: controlling heads based on heating elements forming bubbles