MECHANISM FOR DETECTING POSITIONS OF MIRROR AND SHIELDING PLATE

摘要

PURPOSE:To detect the positions of a mirror and a shielding plate by a common position sensor without individual detection of the mirror and the shielding plate by detecting the rotational position of a driving plate through a signal plate. CONSTITUTION:A frame 20 fixing the mirror 11 and the shielding plate 12 are pivoted around a shaft 21 so as to be optionally rotated. The driving plate 24 is rotatably fitted to one side of a mirror box 10 and driven by a motor 28 through gears 25-27. A mirror driving pin 32 and a shielding plate driving pin 33 are fitted to the driving plate 24 and the sector signal plate is also fixed on the driving plate 24. Photosensors 70, 71 turn the states of output signals instantaneously at the passage of the edges 35a, 35b of the signal plate 35 rotated integrally with the driving plate 24. Consequently, it is unnecessary to individually detect the positions of the mirror and the shielding plate and the number of position sensors requiring highly accurate positioning can be reduced.