The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 21, 1992
Filed:
Aug. 26, 1991
David A West, Streamwood, IL (US);
Zebra Technologies Corporation, Vernon Hills, IL (US);
Abstract
The heating elements of a thermal printing head are respectively driven through drive transistors under the control of strobe pulses and are respectively provided with temperature control circuits, each such circuit including a sense resistor connected in series between the heating element and the drive transistor for sensing the current flow therethrough. Each control circuit has a flip-flop which is clocked by an associated strobe signal to turn on the corresponding drive transistor. The voltage drop across the sense resistor of each control circuit is amplified and compared to a reference level corresponding to a predetermined temperature, and when it exceeds the reference it resets the associated flip-flop to turn off the corresponding drive transistor.