Phototransistor apparatus with current injection ambient compensation
Patent 4713534 Issued on December 15, 1987. Estimated Expiration Date: 
February 18, 2006. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
February 18, 2006. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 3764813 3811046 Presence detecting system with self-checking Ambient light compensating circuit Touch entry interactive cathode ray tube arrangement Touch panel with ambient light sampling Touch sensitive computer input device Photoelectric input apparatus Patent #: 4267443 InventorsApplicationNo. 06/830408 filed on 02/18/1986US Classes:250/214B, Ambient light desensitizing means250/221, Controlled by article, person, or animal327/514, Light327/94, Sample and hold345/173Touch panelExaminersPrimary: Westin, Edward P.Assistant: Ruoff, Jessica L. Attorney, Agent or FirmInternational ClassesG06F 3/033 (20060101)H03K 17/94 (20060101) AbstractA 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. | |
