Seikosha Co., Ltd.

Kanji Ito

Kazuo Akimoto

Shigeru Tagami

Katsuhiko Matsushita

Michio Kawai

Mitsuhiro Kakuta

Yoichi Seki

Hiroyuki Saito

Tadashi Ishikawa

Takahito Otora

Hiroto Tsuyuki

Teruyo Hayakawa

Tomihiko Aoyama

Takayuki Sato

A photographic camera has a rectilinear approximate operation circuit for calculating characteristic correction data for correcting errors in the operational characteristics of the camera. Predetermined theoretical characteristic data dependent on operational characteristics of the camera are stored. Measured data corresponding to predetermined measured values are stored as individually measured characteristic data in a nonvolatile EEPROM so that the stored measured data can be easily changed by rewriting the EEPROM. An object signal is generated depending on an object to be photographed. The rectilinear approximate operational circuit calculates characteristic correction data from the object signal, the theoretical characteristic data and the measured characteristic data, which is then used for correcting errors in the operation characteristics of the camera.

Device for correcting characteristic errors of a camera

A camera shutter system includes a matrix memory, an arrangement for determining the initial speed of a shutter sector, and a source of exposure values. The memory stores shutter-exposure pulse data elements, and is addressed by functions of the determined speed and the exposure values. A motor coupled to the sector is controlled in response to an accessed pulse data element. The data elements may relate only to variable portions of movement of the shutter, and be added to fixed values in order to minimize the size of the memory.

Camera shutter

A camera shutter system has a motor driven sector for opening and closing a shutter opening. A photo-interruptor is positioned to intercept a light beam, to effect the outputting by the photo-interruptor of a signal pulse corresponding to the speed of the shutter. A memory storing exposure data, such as a matrix memory, is accessible as a function of the speed signal and an exposure quantity that is a function of the brightness of the brightness of an object to be photographed. The accessed exposure data is modified as a function of an observed exposure quantity.

Arrangement for compensating for variable speed of a camera shutter

A camera shutter system has a motor driven sector for opening and closing a shutter opening. A photo-interruptor is positioned to intercept a light beam, to effect the generation of a photo-interruptor signal. A timer has a counter that is set to a first count in response to the photo-interruptor signal, and is reset when a given count is reached. A shutter malfunction signal is generated when the level of the photo-interruptor signal has not changed by the time the given count is reached.

A camera shutter system has a motor driven sector for opening and closing a shutter opening. A photo-interruptor is positioned to intercept a light beam, to effect the sequential generation of first and second photo-interruptor signal pulses, the first pulse having a width that is a function of the speed of the sector. A timer has a counter that is set to a first count corresponding to an exposure value that is a function of the brightness of an object to be photographed and the width of the first photo-interruptor signal. The timer is controlled to count down in response to the second photo-interruptor signal, and the sector driving motor is energized during the count down of the timer.

An exposure control unit for controlling a motor-driven shutter includes an arrangement for interpolating, with linear approximation, between values in an exposure data table, in order to enable finer adjustment of the shutter without increasing the amount of stored table data.

Exposure control unit for a motor-driven shutter

In a camera having a lens shutter and a focal-plane shutter accomplishing the operations of programed exposure and aperture control, a flash photography changeover device includes a first changeover circuit for setting a lens shutter mode for operating the lens shutter as a programed shutter or a focal-plane shutter mode for controlling the shutter speed by the focal-plane shutter and the aperture by the lens shutter; a first driving device for controlling the programed exposure value and/or the aperture value of the lens shutter; a second driving device for controlling the shutter speed of the focal-plane shutter; a sequence control circuit for controlling the operating timings of the two driving devices; a setting circuit for selecting and setting automatic exposures with a natural light and a flash light; and a coercive changeover circuit for setting the lens shutter mode irrespective of the setting of the first changeover circuit when the setting circuit is set to the automatic exposure with the flash light. The setting circuit and the coercive changeover circuit may be replaced by a determining circuit for detecting and determining a limit shutter speed at which the focal-plane shutter is synchronized with the flash light; and a coercive changeover circuit for setting the lens shutter mode irrespective of the setting of the first changeover circuit for setting the shutter mode, when the determining circuit determines that the shutter speed exceeds the limit speed.

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Chiba, Japan

Kanji Ito