| 摘要 |
1,149,623. Photo-electric camera exposure control. BELL & HOWELL CO. May 18, 1966 [May 20, 1965], No.22097/66. Heading G1A. [Also in Divisions G2, G4 and H3] An automatic camera exposure apparatus adjusts the diaphragm opening and shutter speed in dependence upon both the illumination of a scene and any motion in the scene. A photo-detector 30, preferably a photo-resistor, receives an image of the scene through a grating 32 so that as the object moves, in a direction transverse to a line between the object and camera, its image moves across the grating to give an alternating output from the photo-detector whose frequency is proportional to the speed of the object. This output signal is amplified and triggers a monostable multi-vibrator 36 to provide regularly shaped pulses and a D. C. signal is created at integrator 38 which is linearly proportional to frequency of the pulses. This D.C. signal by itself controls the shutter speed and together with a signal indicative of the illumination from photo-detector 24 provides a signal of from sum- - ming circuit 41 to control the diaphragm opening. Film speed variations are provided for by an adjustable plate in front of photo-detector 25. The grating 30 may have horizontal, diagonal or circular opaque and transparent lines or alternatively differing reflective areas. Instead of using a multi-vibrator 36 (also Fig. 6 not shown) a pulse clipping and shaping circuit can be used Fig. 11 (not shown). |
