| 摘要 |
<p>1466369 Shutter-diaphragm POLAROID CORP 14 May 1974 [22 May 1973] 21291/74 Heading G2A A shutter-diaphragm is opened and closed in discrete steps by a stepper motor 60. As shown, a shutter-diaphragm comprises blades 26, 28 having apertures 30, 32 which overlap to form an exposure aperture, and apertures 46, 48, which overlap to form an aperture for a photo-cell of a light sensing circuit, (136), Fig. 7 (not shown). As described, pulses are fed to motor 60 which drives a pinion 34 engaging racks on the blades to open the exposure aperture until an exposure terminating signal is received from the light-sensing circuit. The motor is stopped and, after a one pulse delay to allow for inertia, is reversed to close the shutter. If full aperture is reached before receipt of the exposure terminating signal, a pulse counter (154) stops the motor and the aperture is held open until the terminating signal is received. Preferably the shutter is closed by pulses of higher frequency than the opening pulses. Logic controlling the whole sequence of operations in an SLR camera is described.</p> |
