| 摘要 |
PURPOSE:To read a multi-gradation image by increasing the bit number of an A/D converter equivalently. CONSTITUTION:Light from a fluorescent lamp 33 is reflected on an original 31, converged on an image sensor 35 by a lens array 34, and its output is inputted to an adder 3. Random data from a digital pattern generating circuit 7 is subjected to D/A conversion 6, is inputted to the adder 3, the added output is fed to an N-bit A/D converter 4 and inputted to a fuladder 5 as (M+N)-bit data while adding M bits of 0 data to the N-bit low order. On the other hand, the output M bits of the circuit 7 is inverted (8), 1 data of N bits is added to the high order and the result is inputted to the adder 5. The output of the adder 5 is n+M bits being the subtraction of the output of the circuit 7 from the output of the A/D converter 4 expanded into (N+M) bits.
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