Patent ID: 6873282

Claim:
A method for differential elapsed-time analog-to-digital conversion, comprising: a. initializing an output of a first sensor to a first initial output level b. allowing said output of said first sensor to change from said first initial output level in response to incident energy c. measuring a first elapsed time required for said output of said first sensor to change from said first initial output level to a first threshold level d. initializing said output of said first sensor to a second initial output level e. allowing said output of said first sensor to change from said second initial output level in response to incident energy f. measuring a second elapsed time required for said output of said first sensor to change from said second initial output level to a second threshold level g. combining said first elapsed time and said second elapsed time whereby in conditions of substantially constant incident energy said first elapsed time and said second elapsed time are functions of said first initial output level, said first threshold level, said second initial output level, and said second threshold level.