Magnet warning device for focal plane electric shutter camera

Abstract

A mechanical arrangement is disclosed for blocking the electric shutter operation of a camera when the rear shutter holding electromagnet is not energized sufficiently to hold the rear shutter. A pair of gears for the front and rear shutters, respectively, are mechanically linked to the shutters to prevent their running when the gears are held stationary. A release controlled lever holds the front shutter gear stationary, and the stationary position of the front shutter gear holds the rear shutter gear stationary. When the release button is depressed the front gear is released from the lever and rotates as the front shutter runs to an unblocking position. Rotation of the front gear frees the rear gear, but the rear shutter is held by the electromagnet until the exposure time is completed. Thereafter the electromagnet is deenergized causing the rear shutter to run to its blocking position and the rear shutter gear to rotate. If the electromagnet is not sufficiently strong, e.g. because of a reduction in battery power, to hold the rear shutter, both shutters will start to run and both gears will start to rotate simultaneously. A lever held in a first position by the starting position of the rear shutter gear, moves to a second, blocking position, when the rear shutter gear starts to rotate. When in the blocking position, the lever stops further rotation of the front shutter gear which, in turn, stops further rotation of the rear shutter gear. The operator, as a result, hearing no running sound of the shutters knows there is a failure in the electromagnet circuitry.

Dependencies are inferred from the claim text.