US 4,786,930 AGranted

Lens shutter using an electrostrictive strain element as driving source means

AssigneeCopal Company Limited

InventorsAkira Suzuki, Haruki Oe, Kiyoshi Touma

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Abstract

A lens shutter using an electrostrictive strain element as a driving source, arranging a shutter blades opening and closing lever and the electrostrictive strain element driving the opening and closing lever so that inertia forces acting on the opening and closing lever through engagement with the electrostrictive strain element and acting on the electrostrictive strain element through engagement with the opening and closing lever are counterbalanced by each other, in order to eliminate variations of exposure caused by various positions of a camera. The basic portion of the electrostrictive strain element is secured to a retaining member supported rotatably on a shutter base plate and the retaining member may well be biased by a spring to increase the inertia force of the electrostrictive strain element. Thereby, even if a shock is applied to the shutter from the outside, it does not occur that the shutter blades are inadvertently opened and closed. The rotation of the retaining member to rotate the opening and closing lever in a direction to open the shutter blades through the electrostrictive strain element is prevented by an eccentric pin.

Claims4

Dependent claims

A lens shutter using an electrostrictive strain element as driving source means, comprising:

a base plate having an exposure aperture;
shutter blades supported rockably on said base plate to open and close said aperture;
said electrostrictive strain element which has properties that said element is biased by application of voltage and is returned to an original form by discharge of stored electric charge and which is constructed to be fixedly held at one end by a retaining member provided on said base plate and to be free at the other end;
and
an opening and closing lever supported rotatably on said base plate so that two arms are different in length from each other and engaged with said shutter blades at an end portion of a long arm and with the free end of said electrostrictive strain element at an end portion of a short arm to open and close said shutter blades through the bias and restoration of said electrostrictive strain element,
said electrostrictive strain element and said opening and closing lever being arranged so that an inertia force acting on said opening and closing lever through engagement with said electrostrictive strain element are counterbalanced by that acting on said electrostrictive strain element through engagement with said opening and closing lever.

3 more elements

Dependencies are inferred from the claim text.