Automatic exposure control apparatus for a single lens reflex camera

摘要

An automatic exposure control apparatus for controlling the diaphragm of the camera in accordance with the preselected shutter time and the exposure value, in which a digital-to-analog converter having a counter responsive to the number of pulses supplied from a clock pulse generator through a gate produces a time variable output capable of attaining a certain level dependent upon the preselected shutter time and a light value as photoelectrically sensed, that is, an exposure value and, which is detected by a first comparator. The output of the first comparator is applied to the gate, so that the converter is set to memorize the exposure value therein. As the diaphragm presetting ring is moved from the maximum to minimum aperture position with production of a time variable output from a signal generator associated therewith, a second comparator responsive to the attainment of the time variable output of the signal generator to a level dependent upon the final output of the set converter produces an output which is applied to arresting means for the diaphragm presetting ring. This results in automatic adjustment of the position of the presetting ring. At the time the presetting ring begins to move, the diaphragm driving means is actuated causing the diaphragm means to be brought into engagement with the ring. Thus, an effective exposure aperture is established in the diaphragm means.