| 摘要 |
1,257,052. Automatic exposure control. EASTMAN KODAK CO. Jan. 9, 1969 [Jan. 11, 1968(2)], No.1294/69. Heading G2A. Aperture opening or closing movements of slidable diaphragm plates 12, 13 which have co-operating apertures 15, 18 and 17, 16 to cover or uncover lens aperture 26 and photocell aperture 27 provided in a plate 14 is controlled via rack and pinion gearing 19, 20 and 6<SP>1</SP> by a continuously rotating drive roller 11 engaging either the outer or inner surface of a groove 9 provided in a pulley 8. The pulley 8 has a gear 10 which engages the gear 6, and the pulley is mounted for rotation about a pin 7 provided on an armature arm 4. The armature arm is associated with two electromagnets 1, 2 and attraction of the armature from one electromagnet to the other causes relative movement between groove 9 and drive roller 11 to thus reverse the direction of drive of gear 6, upon neither electromagnets being energised a spring 4<SP>1</SP> biases the armature arm into an intermediate position in which no drive is transmitted from roller 11 to pulley 8. The photo-resistor Pc controls the switching of two Schmitt Triggers which are connected to the electromagnets, the circuit arrangement being such that at low light levels one electromagnet is energized so that the apertures are opened until the photo-resistor receives sufficient illumination to de-energize the electromagnet and a neutral state is reached. If too much illumination reaches the photoresistor, the other Schmitt Trigger switches over to energize the other electromagnet so as to close the apertures until a neutral state is again achieved. Any type of exposure regulate such as those which change the shutter speed or diaphragm aperture or both may be used in place of the slide plate type of exposure regulator illustrated. The drive roller 7 may be coupled to the drive motor of a cine camera. |
