| 摘要 |
<p>PROBLEM TO BE SOLVED: To stably detect an object even in the case that the distance between a light emitting element and the object or the distance between the object and a light receiving element is increased and the intensity of a light entering the light receiving element is decreased, by a method wherein duty ratio is increased and a driving current driving the light receiving element is controlled to be small. SOLUTION: When the distance between a light emitting element 3 and an object 4 to be detected or the distance between the object 4 and a light receiving element 5 is increased, and the intensity of a light entering the light receiving element 5 is decreased, or when an object of low reflectance is to be detected, control is performed as follows; on the basis of relation between duty ratio and the maximum driving current of the light emitting element, a control signal (c) is input from a control terminal, the duty ratio of a pulse generator 12 is decreased, and the output current of a low current circuit 13 is increased by the control signal (c). Thereby the object can be stably detected, when the distance between the light emitting element and the object or the distance between the object and the light receiving element is increased and the intensity of the light entering the light receiving element is decreased.</p> |
