Importance

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Abstract

A system having a sensor, a feedback loop comprising a controllable load and an integrator, and a comparator. The light filter is matched to the sensor to allow enough light to be sensed while appearing dark. Current produced by the sensor is received by the controllable load, across which a voltage is detected. Upon a relative change in light intensity, a difference between the detected voltage and a reference voltage is integrated by the integrator over an integration time to produce a feedback signal. The feedback signal completes the feedback loop by controlling the controllable load's impedance and adjusting the value of the detected voltage back to the value of the reference voltage. Thus, relative changes in light intensities are detected while thereafter adjusting to the ambient light conditions. When the difference between the detected voltage and the reference voltage is greater than a preset value, the comparator alters an output voltage. The altered output voltage indicates enough of a relative change in light intensity that the interactive device can appropriately respond to the new covered or uncovered sensor condition. The integration time may be reduced within the integrator when going to a brighter light intensity condition incident to the sensor to meet user expectations. Furthermore, a timer circuit may be used to reset the integration time by providing a reset signal to the integrator once a predefined period of time elapses after the sensor is covered or uncovered.

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First Claim