| 摘要 |
<p>PURPOSE:To identify a scanning direction by using a pad where optical reflection zones in which a reflectance gradually increases when scanning is executed in one direction and the reflectance gradually decreases when scanning is executed in an opposite direction are repeatedly arranged in parallel. CONSTITUTION:The optical reflection zones 1A in which the red reflectance gradually increases when scanning is executed in one direction and it gradually decreases when scanning is executed in the opposite direction are repeatedly arranged in warp streak for the pad 1. A red light-emitting part 5a scans the pad 1 in a right direction and a red light-receiving part 7a receives light so as to obtain a sawtooth output signal 6. Then, an ATLC circuit 24 obtains a reference signal 23 and a comparator 31 compares the output signal 6 with the reference signal 23. Then, the pulse wave 29 of a positive polarity can be obtained in a place where the levels of both signals are inverted. Since the polarity of the pulse wave 29 is positive, that the scanning direction is the right direction can be identified. Next, the pulse wave 29 of the negative polarity is obtained when scanning is executed in a left direction and that the scanning direction is the left direction is identified.</p> |
