Motor drive camera shutter - comprises lamellae with signal edges in bordering region for opening or closing according to rotation of motor

摘要

A light interrupting unit (19) has a light sensing and a light receiving element to deliver first and second light interruption signals in connection with first, second or third signal edges of the shutter lamellae (17). A timer provides a count value dependent on the light of the subject and uses the first interruption signal. It starts counting in response to the second interruption signal. A drive unit (DV) controls the motor (MT) according to the count value given by the timer. A shutter lamella has a designated first edge (17b) and a rectangular aperture (17c) whose front edge serves as the second edge and its rear edge as the third. These edges break the light beam (19a) of the photo-coupler (19) or let it through to generate the first or second interruption signal. The first delivers a start speed coefft. (TS). ADVANTAGE - Copes with vagaries such as drop in battery power, variation of discharge peak due to conflict between motor load in driving shutter and other loads, and changes in use of camera, e.g. position, temp. and humidity.