| 摘要 |
<p>PROBLEM TO BE SOLVED: To detect presence of a mending tape applied onto a paper accurately by arranging a first light receiving element to receive a light reflected at an angle larger than the incident angle of light from, a light source impinging on an object. SOLUTION: Upon receiving an oscillation output from an oscillation circuit 20, a projection pulse generating circuit 21 generates a projection pulse signal and drives a light source 1. The light source 1 projects a pulsating light and the light reflected on a work is received by two light receiving elements 2a, 2b and converted into electric signals. These electric signals are fed to peak hold circuits 22a, 22b where the peak values are detected and delivered to a decision circuit 24 which then produces a detection signal. More specifically, an element 2a receiving a light reflected at a larger angle than the incident angle of light from a light source impinging on an object captures variation in the quantity of light reflected regularly on a mending tape and then the quantity of received light is compared between the elements 2a, 2b thus detecting the mending tape.</p> |
