| 摘要 |
PROBLEM TO BE SOLVED: To provide a reading speed corresponding to resolution and to prevent the output level of an optic/electric converted signal from being lowered, even when the reading speed is accelerated by controlling the amplification factor of an amplifying means through a resolution control means. SOLUTION: Signal output amplifier blocks 6 and 6' are connected with a resolution switching signal (MODE). The signal output amplifier blocks 6 and 6' are provided with a means for changing the amplification factor, corresponding to the resolution to be switched by the MODE signal. The gain varying means of the signal output amplifier block 6 is equipped with a reference voltage. Corresponding to the inputted resolution switching control signal (MODE), an analog switch is changed over, and a resistor connected to a gain amplifier is switched as well. Therefore, the voltage corresponding to the resolution is inputted to the inverting terminal of the gain amplifier. As a result, the signal output amplifier block 6 can obtain amplifier gain corresponding to the resolution switching control signal (MODE), namely the resolution.
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