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:
Dec. 17, 1991
Filed:
Oct. 11, 1990
Fumihiro Shimada, Hyogo, JP;
Hisashi Uemura, Hyogo, JP;
Kanzaki Paper Mfg. Co., Ltd., Tokyo, JP;
Abstract
A detection circuit for determining whether heating members within a thermal head are broken is disclosed. The circuit comprises a voltage source connected in series with a resistor, wherein the voltage source and resistor are connected in parallel with a diode. The diode allows current to flow from a thermal head driving power supply to a thermal head. invention also includes a comparator for comparing the voltage The present level at the output terminal of the diode with a reference voltage. The parallel connection of the diode and the voltage source/resistor allows the output voltage of the diode to maintain an expected voltage level while the heating members are operating normally (i.e. the members are not broken). The parallel connection also allows the voltage level at the output terminal of the diode to increase as the members operate abnormally (i.e. a worn or broken condition). The comparator monitors this voltage level, and detects undesirable fluctuations therein. Thus the circuit of the present invention prevents printing of incorrect letters.