Electric lamp and discharge devices: systems – Pulsating or a.c. supply – Plural load device systems
Patent
1981-03-31
1982-08-17
Hix, L. T.
Electric lamp and discharge devices: systems
Pulsating or a.c. supply
Plural load device systems
354 60F, 354127, 315241P, 315151, 315158, G03B 1505, H05B 4134
Patent
active
043446809
ABSTRACT:
In a photographic system for flash photography, the firing current of an electronic flash tube is selectively restricted in accordance with the detection of whether or not the flash light amount necessary for a flash photograph is below a predetermined level prior to the firing of the flash tube for a photographic exposure. A selection is made between a first mode of flash firing with flash tube current flowing through a switching element and a second mode of flash firing with a flash tube current flowing through an impedance device serially connected with the flash tube. Alternatively, a selection can be made between higher or lower voltage levels to which the main flash firing capacitor is charged. The amount of light required from a flash device can be preparatorily identified and when less than a predetermined light output the flash device is caused to select the second mode of flash firing, or alternatively to select the lower level of the voltage charged by the main capacitor. The operation of the flash tube is controlled such that the flash light emission therefrom substantially corresponds to the necessary flash light amount such that a reduction is obtained in the ratio of excessive amount of flash light to the necessary amount of flash light.
REFERENCES:
patent: 4241279 (1980-12-01), Numata
patent: 4285585 (1981-08-01), Numata
Ishida Tokuji
Itoh Masatoshi
Izumi Tatsuro
Matsumoto Toshiaki
Niwa Masatake
Hix L. T,.
Minolta Camera Kabushiki Kaisha
Perkey William B.
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