| 摘要 |
<p>PURPOSE:To improve the S/N for printing and discriminating accurately the code information, by extracting a signal corresponding to the print contents through a BPF having variable pass bands and an LPF, and therefore compressing the noise quantity contained in the signal detected through a magneto-resistance element. CONSTITUTION:The voltage of a constant voltage supply 3 is applied to the magneto-resistance elements 1 and 2, and the voltage change of a junction P between the elements 1 and 2 is differentiated by a capacitor 4 and a resistance 5 of a differentiating circuit and applied to an amplifier 6. The signal V1 corresponding to the print contents extracted through the amplifier 6 is applied to a BPF circuit 7 having variable pass bands. The outputs of BPF81-8n of the circuit 7 are selected by the signals given from a switch signal producing circuit 10 and by using the switches 91-9n successively. Then the signal V2 selected by each of the switches 91-9n is applied to an LPF11. The noise quantity contained in the signal V1 detected by the elements 1 and 2 is compressed. Thus the S/N of the signal V1 is improved for printing. As a result, the code information can be accurately discriminated.</p> |
