| 摘要 |
<p>Visible light from a light emitting device (1) passes through the transparent portion of a tape (2) to be supplied to light receiving devices (3)(4), thereby detecting the end portion of the tape (2). The light emitting device (1) radiates visible light with certain periods, and the encountering of the end portion or the beginning portion of the tape is recognized only when the period of the output pulses of the light receiving devices (3)(4) corresponds with the period of the light emissions of the light emitting device (1). The conventional disadvantage of frequent errors is removed.</p> |
