Fuji Photo Film Company, Limited

Nidec Copal Corporation

Copal Company Limited

Takanori Kohno

Tomio Kurosu

Kouichi Kobayashi

Tetsuo Sakamoto

Mutsumi Naruse

Norifumi Nakagawa

Fumio Ishihara

Teruyuki Tongu

An optical range finder has a projection unit for projecting optical flux to an object, a photoreceiving unit for receiving the optical flux returned from the object and outputting a detection signal in accordance with a light quantity of the received optical flux, and a circuitry unit for conducting a measurement of a distance to the object based on the detection signal. In the circuitry unit, a light quantity determination circuit compares a signal level of the detection signal with a reference level to carry out binary determination of the light quantity of the returned optical flux. A reference level setting circuit switchably supplies a plurality of reference levels to the light quantity determination circuit, the reference levels being preset in correspondence to multiple stages of the distance. A control circuit controls the reference level setting circuit to supply the reference levels while switching the reference levels so as to enable the light quantity determination circuit to execute a plurality of the binary determination with the supplied reference levels for one measurement, thereby specifying the distance to one of the multiple stages based on the thus obtained plurality of the binary determination.

Range finder of light amount detection type with multi zone resolution

A motor driving apparatus is basically composed of a driving circuit for driving a plurality of loads contained in a plurality of motors, and a control circuit for controlling the driving circuit to sequentially drive the plurality of the motors. The driving circuit has at least two channels which are controlled by the control circuit concurrently with each other. Each channel is controlled by the control circuit such as to selectively drive the loads. The channel is provided with at least (n&plus;1) number (n: integer of 2 or greater) of output terminals to connect at most n number of the loads. The control circuit controls the driving circuit to perform an intra-channel driving mode in which one pair of the output terminals are selected from one channel and allocated to drive one load, and an inter-channel driving mode in which another pair of the output terminals are selected from two channels and allocated to drive another load.

Motor driving apparatus

Method and apparatus for controlling exposure of camera

An exposure control method and apparatus for a camera having a two-area divided brightness measurement system. A central light value is determined based on a central area brightness of a photographic scene, and a peripheral light value is determined based on a peripheral area brightness of the scene. After determining by comparison between the central and peripheral light values whether the scene is back-lighted or front-lighted, a correction coefficient specific to back-lighted scenes or that specific to front-lighted scenes is read from a memory. An exposure value suitable for a main subject is calculated according to the following equation:

A program shutter adapted to close shutter blades having the function of diaphragm blades by a cam member operated with an electric motor has improved control accuracy in high brightness. A blade opening and closing member for opening and closing the shutter blades is urged to open the blades and driven to close the blades by the cam member operated by the motor. Brightness of an object to be photographed is measured by a brightness measuring portion and an area of a plurality of areas of brightness in which the measured brightness is contained is decided by a brightness decision portion. An exposure control circuit starts measurement of the exposure time when the shutter blades are operated to a predetermined trigger point. The cam member is previously moved to the limitation that movement of a blade driving member is not prevented in accordance with the brightness area in which the current brightness is contained before the exposure control circuit generates the exposure end signal. Thus, a closing delay time at time that the blade opening and closing member is moved to close the shutter by the cam member in response to the exposure end signal is shortened. Consequently, the trigger point for starting the exposure control circuit can be established in a position in which moving operation of the shutter blades just before the shutter blades form a pin hole is stable and exposure accuracy is improved.

Control unit for a program shutter

A control circuit for a programming shutter includes a light receiving element which is always exposed to light from a subject to be photographed and a logarithmic compression device which logarithmically compresses a photocurrent flowing through the light receiving element in accordance with the brightness of the subject. An output voltage of the logarithmic compression device is logarithmically expanded by a logarithmic expansion device and a logarithmically expanded current from the expansion device controls currents flowing through a plurality of weighted current sources. The currents flowing through the plurality of weighted current sources are added to or subtracted from a charged current to a condenser for integrating the brightness of the subject through a plurality of current switches corresponding to the current sources. On the other hand, shutter blades having the function of the diaphragm are opened in accordance with a predetermined opening characteristic in interlocked relationship with the shutter release operation and a counter is operated in interlocked relationship with the opening operation of the shutter blades. A count of the counter controls operation pattern of the current switches so that the charged current to the integrating condenser is conformed to the opening characteristic of the shutter blades. Further, a bias voltage for the logarithmic compression device is proportionated to an absolute temperature and is established to correspond to the film speed so that the parameter proportional to the absolute temperature is eliminated from the output current of the logarithmic expansion device.

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Tokyo, Japan

Takanori Kohno