Programme-controlled shutter

A programme-controlled shutter comprising

• a. an exposure control mechanism comprising
• a stepping motor, and
• a plurality of shutter blades which function also as aperture setting blades and which are mechanically coupled to said stepping motor in such a way that when said stepping motor is driven, said shutter blades are opened and closed;
• b. a motor control circuit with a first input terminal to which are applied the pulse signals for driving said stepping motor and a second input terminal to which is applied the signal for determining the direction of rotation of said stepping motor;
• c. a pulse generator circuit for generating said driving pulses in succession;
• d. a memory circuit having a plurality of output terminals and generating the output signals at said plurality of output terminals in response to the number of the pulse signals transmitted thereto from said pulse generator circuit;
• e. a first control means including a first photometric circuit for measuring the brightness of a subject, said first control means controlling said pulse generator circuit by the comparison of the output signal from said first photometric circuit with the output signals from said output terminals of said memory circuit;
• and
• f. a second control means including a second photometric circuit for measuring the brightness of a subject, said second photometric circuit being actuated in response to the output signals from said output terminals of said memory circuit,
• said second control means generating the closing signal for closing said shutter blades when the light brightness detection quantity measured by said second photometric circuit reaches a predetermined level.
• said closing signal being applied to said second input terminal of said motor control circuit and to said first control means, whereby said shutter blades are closed.