Camera flash light control circuitry

Abstract

In a flash photography system including an electronic flash device adapted to be combined with a camera which is adapted to transmit first and second signals to an electronic flash device and to receive third and fourth signals therefrom, and wherein the third signal informs the camera of the completed preparation for flash light emission; the first signal directs the electronic flash device to initiate flash light emission; the fourth signal directs the camera to initiate light measurement upon flash light emission; and the second signal directs the electronic flash device to terminate flash light emission in accordance with the light measurement. The electronic flash device incorporates a flash light emitting device, storage of electric power for operation of the flash light emitting device, a circuit for generating the third signal with the stored electric power exceeding a predetermined level, first, second and third terminals connected to the camera for respectively receiving the first signal, transmitting the third signal, and receiving the second signal; circuitry for initiating flash light emission in response to the first signal; circuitry for providing the fourth signal in response to the first signal; and circuitry for terminating flash light emission in response to the second signal. The circuitry is capable of modifying the third signal into the fourth signal in response to the first signal and changing the third signal into different voltages depending upon the electric power stored; and modifying the third voltage into the fourth signal if the stored power exceeds a predetermined level. Circuitry enables the third signal to connect with the second terminal in the absence of the first signal and to transmit to the second terminal the fourth signal in place of the third signal in response to the first signal.

Dependencies are inferred from the claim text.