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. 15, 1987
Filed:
Feb. 18, 1986
Applicant:
Inventors:
Timothy E Masters, Georgetown, TX (US);
Wayne J Wehrer, Austin, TX (US);
Assignee:
Carroll Touch Inc., Round Rock, TX (US);
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H01J / ;
U.S. Cl.
CPC ...
2502 / ; 307311 ;
Abstract
A current injection compensation circuit for dynamically compensating for the effect of ambient conditions on phototransistor output is disclosed. An output voltage is maintained at a nominal reference voltage level independent of ambient light input to allow use of a large output for a detected signal. Phototransistor current is a function only of ambient conditions, especially incident ambient light and is unaffected by compensation current injection. The ambient compensation current injection network can be employed with interactive touch input devices, such as infrared touch entry systems used with video displays.