Photographic camera with an electromagnetic control system

An electromagnetic actuating device adapted to control initiation of release of at least one internal mechanism of a photographic camera, which device comprises:

• an electromagnet, having:
• (a) a core made of a semihard magnetic substance having magnetizing characteristics forming a substantially rectangular hysteresis loop;
• (b) coil wound around said core;
• (c) an armature associated with said mechanism and arranged to be fixed in position when a magnetic flux is established in said core and to be movable with reference to said electromagnet when no magnetic flux is established in said core;
• (d) biasing means for making said armature movable when there is no magnetic flux in said core;
• a first power supply means connected to said coil, wherein said means has a first switch and adds pulse current to said coil for only a short period of time in association with the action of said first switch to magnetize said core;
• a second power supply means connected to said coil, wherein said means has a second switch and adds a pulse current, which is reverse to the pulse current from said first power supply means, to the coil in association with the action of said second switch to demagnetize said core,
• whereby after said electromagnet core is maintained in the magnetized state for a period of time after the termination of the application of said actuating pulse, said deactuating pulse is applied to said coil to initiate the release of said mechanism.