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:
Feb. 28, 1984
Filed:
Dec. 22, 1982
Timothy P Craig, Georgetown, KY (US);
John W Pettit, Lexington, KY (US);
Michael R Timperman, Lexington, KY (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A current-drive circuit (FIG. 1) is provided to drive each of forty electrodes 41. Voltage at the electrodes 41 is monitored on line 49 as a control-input to a voltage-regulator circuit (FIG. 2), to produce the drive voltage Vdr. Vdr minus a current-level reference Vlev is applied as the input of a differential amplifier (transistors 3, 15, 51 and 53), thereby applying Vdr-Vlev on line 27. A constant current through the electrode 41 is produced across register 25. As the lowest voltage at all driven electrodes shifts, the regulator circuit (FIG. 2) shifts Vdr the same amount, employing differentially connected transistors 72 and 74, and Zener 120 to set the level of Vdr. Since most of the active elements operated within narrow limits, the circuit can be extensively miniaturized.