| 摘要 |
PURPOSE:To detect stably and accurately the termination of a tape with no malfunction, by varying the detecting sensitivity of an optical tape end detecting circuit after the splicing tape part is detected and then emphasizing the detecting signal. CONSTITUTION:The irradiating light given from an LEDD1 is reflected to a magnetic part of a tape 12 and received by a phototransistor PTRQ1. The irradiating light from the LEDD1 is reflected to a splicing tape part of the tape 12 and received by the PTRQ1. Thus the AC boltage is delivered to an emitter to turn on an FETQ2, and the characteristics of a bridge circuit at the front stage of an operational amplifier OP1 are changed so as to increase the amplification factor of the OP1. Therefore the amplification of the OP1 is compared with the reference voltage through operational amplifiers OP2 and OP4. In this case, the differential component can be increased. Thus a stable and accurate detecting signal is obtained through an output terminal 13. |
