POSITION/MOVING VELOCITY DETECTING DEVICE FOR MOVING MATTER

PURPOSE:To know the position or the moving velocity of a moving matter from the change of light receiving quantity by making the length of a light shielding means in the moving direction of the moving matter equal to or longer than the sum of the moving range of the moving matter and the width of the moving matter of a photodetecting means. CONSTITUTION:The light shielding plate 13 moves together with the moving matter, and its length L1 in the moving direction 41 is longer than the stroke L of the moving matter, and is smaller than the diameter D of the illuminating circle 42 of a light source in the rectangular direction to the direction 41, and in addition, its width varies linearly between dimension l1 and l2. The photodetector 25 is fixed, and is provided with the light receiving area of width W1>l1 and height (h), and the width of a light receiving region 44 is W2>l2, and the light receiving regions 43, 43' are connected, and input a current to a control circuit. When a device is constituted so as to satisfy the relation of L1>=L-h, the photoelectric current of the light receiving region 44 of the photodetector 25 varies linearly against the position (x) of the light shielding plate 13. Besides, even if the light shielding plate 13 deviates perpendicularly to the direction 41, since the area of the region 44 is constant, the position and the velocity of the moving matter can be known very correctly by keeping the intensity of the light source constant.