| 摘要 |
<p>PURPOSE:To obviate the strict assignment of a sensor in a specific sensitivity rank and simplify a sensitivity adjusting process at the time of assembling manufacture by making the threshold value voltage applied to a comparing means into the optimum value so as to correct the sensitivity of a light receiving means. CONSTITUTION:When a reference reflecting member D is irradiated by a light emitting means A, and the reflected rays from the reference reflecting member D is received by a light receiving means B, the reference value supplied to a comparing means C is changed successively by a reference value changing means E, and the appropriate reference value for detecting the existence of a sheet body P is determined by a reference value determining means F on the basis of the detected result of the comparing means C at this time. The determined reference value and the output value of the comparing means C are then compared at the comparing means C to detect the existence of the sheet body P. As a result, the comparing means C is always provided with the appropriate reference value regardless of secular change, so that detection error is dissolved and the existence of the sheet body P such as paper can be detected positively.</p> |
