Ricoh Company, Ltd.

Yoshihiko Shimura

Susumu Iguchi

Akira Ueno

Hiroshi Takeda

Kazumasa Aoki

Kenji Koyama

Toshiaki Nakahira

Yoshio Serikawa

Shigeru Mitsu

Yukihisa Narazaki

In a range finder, a capacitor for light emission is charged by turning off first and second switching elements and turning on third and fourth switching elements before light is emitted from a light emitting diode. A sum of a charging voltage of the capacitor for light emission and the voltage of a direct current power source is applied to the light emitting diode by turning on the first and second switching elements and turning off the third and fourth switching elements when light is emitted from the light emitting diode. At this time, an operation of the second switching element is controlled with a constant electric current by a constant current control circuit constructed by a transistor, a resistor for current limitation, a diode, etc. so that an electric current flowing through the light emitting diode is constant and a light emitting amount of the light emitting diode becomes constant.

Range finder

A flashing apparatus of an automatic light-adjusting type for illuminating a photographed object by discharging a charge charged to a main capacitor from a light emitting tube has an energy amount detector for detecting an energy amount applied to the light emitting tube from the main capacitor; an energy amount setting device for setting an amount of discharged energy of the main capacitor corresponding to a quantity of light required to illuminate the photographed object; a comparator for comparing the energy amount detected by the energy amount detector with the energy amount set by the energy amount setting device; and a light emission stopping device for stopping light emission of the light emitting tube by a signal outputted from the comparator when the comparator detects that the discharged energy amount of the main capacitor is in conformity with the set amount of the energy amount setting device after the light emission is started. The flashing apparatus may further has a voltage detector constituting the energy amount detector and detecting a voltage applied to the light emitting tube from the main capacitor; an electric current detector for detecting an electric current flowing through the light emitting tube; a multiplying device for multiplying the detected voltage by the detected electric current; an integrator for integrating the multiplied results; etc.

Flash control based on calculated required flash energy

Growing community of inventors

Ichikawa, Japan

Yoshihiko Shimura