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:
Jun. 17, 1986
Filed:
Aug. 14, 1984
NCR Canada Ltd., Mississauga, CA;
Abstract
A system and method are disclosed for automatically detecting any defective elements in a linear array of thermal printhead elements of a thermal printer and for automatically correcting for at least one defective thermal printhead element. In a preferred embodiment of the invention an ON/OFF line from a microprocessor is turned OFF to turn off a voltage regulator, thereby preventing the thermal printhead elements from printing. With the voltage regulator OFF, a diode is forward biased to enable a voltage divider to be formed between a sensing resistor and any one of the thermal printhead elements that is activated at any given time. When a subsequent sense voltage (or resistance measurement) of an element exceeds the value of the initial reference sense voltage for that by a predetermined amount, that element is detected as a defective element. A software subroutine, in the microprocessor is then utilized to change the position of serial data bits carrying data to be printed such that the detected defective thermal element is not utilized during a normal printing operation.