POSITION DETECTOR FOR LENS BARREL OF CAMERA

摘要

PURPOSE:To permit photoelectric detection of the lens barrel position of a camera by applying the position pulse corresponding to the movement of the lens barrel of the camera in accordance with the output pulse of a light receiving element and detecting the movement of the lens barrel of the camera to a reference position in accordance with a change in the amplitude or phase of the output pulse of the light receiving element. CONSTITUTION:The light projected from a 1st light emitting diode 2 and the light projected from the 2nd light emitting diode 3 are applied continuously to a phototransistor 4 when a referenced position signal is outputted. Namely, the light projected from the 2nd light emitting diode 3 is applied through a reference position aperture 7 to the phototransistor 4 in continuation with the light projected from the 1st light emitting diode 2 through a reflector 6 at the outermost end when the lens barrel of the camera arrives at the reference position. The time width of the photoelectric pulse TP of the phototransistor 4, therefore, increases by as much as the light projected from the 2nd light emitting diode 3. The reference position signal of an H level is then applied from the Q terminal of a flip-flop 17 inputted with the photoelectric pulse TP as data and NAND output N2 as clock input to an output terminal 26. The lens barrel position is thereby photoelectrically detected.