Digital display device for digitally displaying correct exposure time

摘要

A digital display device is disclosed which is used for digitally displaying correct exposure time. The display device includes a repetitive pulse generator for generating repetitive pulses to control the charging-discharging operation of an integration capacitor. The number of clock pulses produced by a clock pulse oscillator during the period in which the charged voltage level on the capacitor is increased to the output level of a light measuring circuit which is proportional to the logarithmic value of the brightness of an object to be photographed starting from the voltage level of a reference voltage source is counted by a counter. An LED display is energized by the counter output through a decoder. At this time, the capacitor is charged at the highest possible speed by additional current from a charging speed-up control circuit in addition to constant current from a conventional constant current source, thereby eliminating the necessity of providing a conventional memory device for temporarily storing the immediately preceding digital data already displayed on the display during the period of time till the counter terminates to count the clock pulses necessary for presenting a new digital data to be displayed on the display.