Seikosha Co., Ltd.

Seiko Precision Inc.

Masaki Tanaka

Shigeru Tagami

Nobuo Shinozaki

Kazuo Akimoto

Hiroaki Ishida

Akihiro Ito

Miyoshi Tanikawa

Katauhito Niwa

Yoshio Umezu

A rocking motor comprises a coil wound around a hollow coil bobbin. A rotor is rotatably mounted at a position close to an end portion of the coil bobbin. The rotor has a center shaft and a permanent magnet and is magnetized with two poles such that the positions of the poles are located close to the coil and the magnetization angle is greater than 90 degrees but less than 180 degrees. The positions of the poles of the rotor and the coil are adjacent to one another so that a rotary torque can be efficiently obtained by a magnetic force generated by the coil. The rocking motor can generate a high power output with a relatively low power supply and its operational performance is not adversely affected by an external magnetic field.

Rocking motor

A method of driving a motor-driven shutter for a camera having a sector opening lever which is pivotal to open and close sectors, a sector opening cam movably supported and engageable with an engagement pin provided on the sector opening lever, an actuating member for pivoting the sector opening lever through engagement between the sector opening cam and the engagement pin, and a reversible motor for driving the actuating member. The motor is temporarily suspended when the actuating member is driven to a position where the sector opening cam comes into contact with the engagement pin, and the motor is restarted to cause the engagement pin to reach a predetermined position on the sector opening cam. Thus, it is possible to obtain a stable shutter opening operation and hence increase the degree of aperture accuracy.

Method of driving a motor-driven shutter for a camera

There is disclosed a program shutter for use in a camera. The program shutter consists of a shutter mechanism and a control portion. The shutter mechanism has sectors for defining an opening and a stepper motor for driving the sectors. The control portion produces pulses having pulse width conforming to the operating characteristic of the shutter mechanism. These pulses are used to step the motor forward or backward according to the exposure corresponding to the luminance of the subject.

Program shutter

Growing community of inventors

Chiba, Japan

Masaki Tanaka