| 20100065720 | OPTICAL SENSOR AND SENSING METHOD - An optical sensor includes an infra red LED, a photodectector and a lock in charge amplifier. The photodetector passes charge to a feedback capacitor of the charge amplifier following an illumination cycle during which the LED is emitting and also following an illumination cycle during which the LED does not emit. An amplifier presents an output indicative of the difference between the charge generated at the photodectector during the illuminated and non-illuminated cycles. | 03-18-2010 |
