West Electric Co., Ltd.

Yuji Maruyama

Katsumi Horinishi

Takashi Kobayashi

An electric flash device for photography is controlled of its light radiation of a flash tube by a transistor, which is connected in series with the flash tube and is given its base current through a parallelly connected capacitor and resistor, and when the transistor turns OFF, an electric charge stored in the capacitor is applied across the base and the emitter of the transistor as a reverse bias.

Electric flash device

An automatic electronic flash measures brightness of a predetermined photographing angle including a photographic object, and using the measured brightness and film sensitivity indicates a stop value to be set in camera when the photographic scenery has rear light, and the automatic electronic flash operation is automatically lowered by the extent of F-stop value (automatic F-stop value) of 1-2 EV than the indicated stop value, thereby satisfactory automatic fill-in photographing with the automatic electronic flash can be made; and the automatic electronic flash further comprises means to warn when the brightness of the photographic scenery changes from the measured value, and besides, the above-mentioned controlling corresponding to the automatic F-stop value is examined taking account of the scenery brightness and film sensitivity and produce another warning when automatic F-stop value is an impractical value.

Automatic electronic flash

In an electronic flash device of the type having a power supply unit comprising a low DC power supply and a DC-DC converter and an IC memory which can maintain its stored information even if when a power supply switch is turned off, there are provided a backup capacitor which can maintain the normal and stabilized operation of the IC memory which is connected to the power supply even when the voltage of the power supply drops to such a level that the normal and stabilized operation of the IC memory cannot be maintained; a voltage detecting means for detecting the voltage across the power supply; and a control circuit which responds to the output signal from the voltage detecting means so as to control the operation of the DC-DC converter.

Electronic flash device

An electronic flash device capable of automatically controlling the quantity of a flash of light or a flash duration in response to the intensity of light reflected from a subject, is provided with a means which is responsive to an electrical signal, which is derived from a camera or an arithmetic circuit incorporated in the electronic flash device and represents one of a plurality of f numbers which is selected, so as to control a flash light control means which in turn, for instance, determines a flash duration of a flash lamp and hence the quantity of a flash of light emitted therefrom. Therefore, the quantity of a flash of light can be controlled in steps equal in number to f numbers which can be selected.

Electronic flash device capable of automatically controlling the

An electronic flash of the type incorporating the so-called variable guide number device or a flash duration control device for controlling the quantity of a flash of light emitted from a flash lamp. In an integrating circuit of the variable guide number device diodes are used so that their forward bias characteristics may be utilized for the accurate control of a flash duration.

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Suita, Japan

Yuji Maruyama