| 摘要 |
<p>1336491 Camera exposure control NIPPON KOGAKU K K 29 June 1971 [3 July 1970] 30458/71 Heading G2A A camera exposure control system allows the shutter to be automatically controlled in accordance with object brightness and selected aperture on the aperture to be automatically controlled in accordance with object brightness and selected shutter speed. In both cases the aperture is stopped down first either manually or automatically according to subject brightness and pre-set shutter speed, the brightness of the light passing through the stopped down aperture is measured by a photo-sensitive element and stored by a memory capacitor, and exposure time is controlled by charging another capacitor with its voltage bears a predetermined relation to that of the memory capacitor. As shown for automatic shutter control and pre set aperture, the aperture is stopped down using ring 79, and the shutter release 15 is pressed to move a plate 69 leftwards. This operates a lever 44 to move a shutter opening blade 16. At the same time a switch 90 is opened so that a memory capacitor 91 Fig. 5 is charged according to the light incident on a photo-cell 51 on blade 16, and a switch x is opened so that a capacitor C starts to charge. A differential amplifier DA2 compares the voltage on capacitor C with that on memory capacitor 91 (as modified by a film sensitivity resistor 92) and de-energizes an electromagnet 50 to allow a shutter closing blade 25 to move. For automatic aperture control and pre-set exposure control, a shutter dial 106 sets a resistor 96. When release 16 is pressed, aperture rings 60, 75 close until the voltage due to the illumination of photo-cell 51 compares with that due to resistor 96 and electromagnet 65 is de-energized to release a pawl 62 which arrests rings 60, 75. This sets the aperture according to subject brightness and preset shutter speed. Shutter release then takes place as before. If the shutter speed set is too fast or too slow for the available light the aperture automatically moves to its fully open or almost closed position and the shutter speed is adjusted accordingly. A pointer 109 Fig. 5 indicates the automatically set shutter speed or aperture. Figs. 7, 8 (not shown) depict alternative embodiments as applied to S.L.R. cameras. In Fig. 7 (not shown) a photo-cell 51 is provided on shutter blade 16. In Fig. 8 (not shown) a photo-cell 142 receives light via the pentaprism. Fig. 8 (not shown) also shows exposure time and aperture scales (162, 163) which are selectively movable into the viewfinder ray path.</p> |
