| 摘要 |
PURPOSE:To discriminate a kind of a medium, by storing a signal of a transmission photodetecting element in case when a record on the medium has been detected by a reflection photodetecting element, and outputting said signal until the record on the medium becomes to be not detected by the reflection photodetecting element. CONSTITUTION:When printing of a character, etc. of a moving medium 2 is moved on a transmission photodetecting element 3, an output signal 102 of an amplifier 4 decreases. On the other hand, when a reflection photodetecting element 12 detects the printing of a character, etc. on the medium, its output signal 113 becomes small, and a printing discriminating circuit 13 outputs a discriminating signal 114 which becomes ''1'' only while printing of said character, etc. is detected. A sampling circuit 17 outputs an output signal 102 of the amplifying circuit 4 as an output signal 105 while the discriminating signal 114 is ''0'', and on the other hand, stores the output signal 102 of the amplifying circuit 4 in case when detection of the printing has been started, while the discriminating signal 114 is ''1'', and makes it an output signal 115 and outputs it. Since a field of view of the reflection photodetecting element 12 is made wider than that of the transmission photodetecting element 3, a transmission light signal which does not cause an error by printing is obtained. |
