| 摘要 |
<p>PURPOSE:To prevent a malfunction by equalizing the sensitivity of a 1st optical coupling means consisting of a light emitting element for generating an infrared beam with short beam length and a light receiving element to the sensitivity of a 2nd optical coupling means composed of a light emitting element for generating an infrared beam with long beam length and a light receiving element. CONSTITUTION:Current limiting resistors 41 and 42 are provided on the current paths of light emitting diodes at, for example, corner parts which generate beams, i.e. the rightmost and leftmost light emitting diodes 1110 and 1153 which generate X beams and current limiting resistors 43 and 44 are provided on the current paths of the rightmost and leftmost light emitting diodes 1135 and 1101 which generate Y beams respectively. The values of those resistors 41-44 are so set that the currents of the corresponding light emitting diodes 1110 and 1153, and 1135 and 1101 are made smaller than the currents of light emitting diodes at other parts except the corner parts, thereby equalizing the quantity of light incident on light receiving elements. Consequently, the 1st and 2nd optical coupling means are nearly equalized in sensitivity and the malfunction due to reflected light is prevented.</p> |
