| 摘要 |
PROBLEM TO BE SOLVED: To read information represented by a code different in reflectance at high speed without deteriorating reading quality. SOLUTION: A signal processed by an analog signal processing circuit 10 constituted of a band pass filter(BPF) 15 for scanning a code by irradiating it with beams and detecting the strength of a reflected light beam as an electric signal, a gain control amplifier 18 and a change point detection circuit 21 is detected by a frequency detection circuit 11. The output amplitude of the gain control amplifier 18 is detected by an amplitude detection circuit 12. A control circuit 14 cooperatively controls the output current of the amplitude detection circuit 12, the pass band of BPF 15 in the analog signal processing circuit 10 and the signal transmission characteristic of the change point detection circuit 21 based on the output of the frequency detection circuit 11 or the output of an IF circuit 13 for taking in outer information. |
