| 摘要 |
PROBLEM TO BE SOLVED: To read magnetism even in the instable state of conveyance by performing amplification control while calculating an amplification factor to amplify magnetic information based on detected conveying speed. SOLUTION: An output from a speed sensor 3 is inputted to an A/D converter 4, and that A/D converter 4 converts an analog signal from the speed sensor 3 into a digital signal and outputs it toward a following sub CPU 7 for magnetic processing. The sub CPU 7 detects the conveying speed based on this signal and calculates the amplification factor to the output of a magnetic reading head 2 based on that detected conveying speed. The signal related to this amplification factor is converted into an analog value by a D/A converter 10 and outputted later to a variable amplifier 12. Thus, the variable amplifier 12 performs amplification based on the amplification factor, outputs the result to a signal demodulating part 13 and controls the amplification. |
