| 摘要 |
A method has the first step of accumulating charge in a photo sensor to arrive at a photo sensor voltage. Then, the method increments a value in a counter and determines whether the photo sensor voltage is less than a reference voltage. If the photo sensor voltage is less than the reference voltage, then load a memory with the value in the counter. An apparatus has a photo sensor; a comparator coupled to the photo sensor; a switching element coupled to the photo sensor; an AND-gate coupled to the comparator; and a memory coupled to the AND-gate.
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