| 摘要 |
PURPOSE:To improve the transient response at application of a power which by applying an initial signal shortening a capacitor charge time of a filter means provided to a DA conversion means of the PWM system to the DA converting means tentatively in place of a pulse train at application of the power switch of a camera. CONSTITUTION:An initial signal shortening the charging time of a capacitor C1 being the filter means provided to the DA conversion means 5 is fed to the DA conversion means 5 in place of the pulse train at application of the power switch S 100 so as to detect that the DA conversion output is a predetermined analog quantity in response to the set exposure information, e.g., film sensitivity information directly or indirectly, and when the prescribed analog quantity is detected directly or indirectly, a pulse train in response to the exposure information from the pulse train generating means in place of the initial signal if fed to the DA conversion means 5 by an initial control circuit. Suppose that the capacitor C1 is charged at the low logic of the pulse train, then the charging time of the capacitor C1 is shortened, where T is the pulse period having a duty ratio in response to the exposure information, t0 is the time of low logic and the initial signal is a pulse train having a low logic time of t0<t1.
|
