Diaphragm device

• US 4,797,700 A
• Filed: 06/26/1986
• Issued: 01/10/1989
• Est. Priority Date: 06/28/1985
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Inaba, Hiroyoshi, Tsuji, Sadahiko
• Primary Examiner(s): Mathews, A. A.
• Application Number:
  US06/878,605
• Time in Patent Office: 929 Days
• Field of Search: 354/270, 354/271.1, 354/274, 354/228, 354/229, 354/230, 354/231
• US Class Current: 396/508
• CPC Class Codes: G03B 9/02 Diaphragms
• CPC Class Codes: G03B 9/42 with adjustable slot; with mechanism controlling relative movement of plates to form slot

Abstract

A diaphragm device including a pair of diaphragm blades movable in opposite directions relatively to each other along a moving line passing through an optical axis of an optical system characterized in that each of the diaphragm blades is provided with an opening of a shape consisting of combination of an arc having a center of curvature located on said moving line and at least one arc having a radius smaller than the above-mentioned arc and having a center of curvature located on said moving line or on a line at right angle to said moving line.

Claims

1. A diaphragm device including two diaphragm blades arranged to be movable in parallel relatively to each other along a common line on a plane at right angle to an optical axis of an optical system and having aperture forming cut portions respectively, said diaphragm device further comprising at least one auxiliary diaphragm blade which is movable along said common line on the same plane as the above-mentioned diaphragm blades and has an aperture forming cut portion of the shape different shape from those of the above-mentioned diaphragm blades and amount of relative movement different from those of the above-mentioned diaphragm blades.

2. A blade driving device for driving diaphragm blades in a diaphragm device including a plurality of diaphragm blades movable in parallel relatively to each other on a common plane at right angle to an optical axis of an optical system, said blade driving device comprising a driving source for driving the diaphragm blades, a blade driving lever rotatable around its center of rotation to cause parallel movements of the diaphragm blades, a lever driving arm fixedly connected to the output shaft of said driving source and transmitting the rotation of said output shaft to said lever driving arm, in which the centers of rotation of said blade driving lever and said lever driving arm are arranged in such offset positions from each other that the angle of rotation of said blade driving lever is larger than the angle of rotation of said lever driving arm.

3. A diaphragm device comprising:

a first diaphragm blade,

a second diaphragm blade,

each of said first and second diaphragm blades combining to form an aperture opening having a plurality of arcuate portions havings centers of curvature located on a first straight line and at least two said arcuate portions having a different radius of curvature, and said aperture opening having a plurality of arcuate sections with the centers of curvature thereof located on a second straight line intersecting the first straight line at right angles, and

drving means for driving said first and second diaphragm blades along the first straight line toward and away from one another.