Shutter blades for increasing uniformity of oblique incident light

• US 5,502,525 A
• Filed: 04/18/1994
• Issued: 03/26/1996
• Est. Priority Date: 03/27/1991
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Mizoguchi, Yoshiyuki
• Primary Examiner(s): BLANKENSHIP, HOWARD BENNETT
• Application Number:
  US08/229,395
• Time in Patent Office: 708 Days
• Field of Search: 354/226, 354/228, 354/230, 354/245, 354/246, 354/247, 354/248, 354/265, 354/270, 354/271.1, 354/272, 354/273, 354/274, 348/363, 348/364, 348/365, 348/366
• US Class Current: 396/450
• 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

In a photographing device of the kind having a plurality of blades disposed one after another in an overlapping manner in the direction of the optical axis of a photo-taking lens, with an exposing aperture part for high luminance included in an exposing aperture hole formed in each of the blades, and performing exposure control for an exposure surface by driving and moving these blades relative to each other in the direction of traversing the optical axis, the fore end positions, relative to the optical axis, of the exposing aperture parts for high luminance included in the exposing aperture holes formed respectively in the blades are arranged to be located farther away from the optical axis accordingly as the blades are located farther away from the exposure surface.

Claims

1. A photographing device having a plurality of blades disposed one after another in an overlapping manner in the direction of an optical axis of a photo-taking lens, with an exposing aperture part for high luminance included in an exposing aperture hole formed in each of said blades, and performing exposure control for an exposure surface by driving and moving said blades relative to each other in the direction of traversing the optical axis, characterized in that:

fore end positions, relative to the optical axis, of said exposing aperture parts for high luminance included in said exposing aperture holes formed respectively in said blades are arranged to be located farther away from the optical axis accordingly as said blades are located farther away from the exposure surface, and wherein the exposing aperture holes are arranged to adjust an amount of light incident through said photo-taking lens.

2. A device according to claim 1, wherein the force end positions, relative to the optical axis, of said exposing aperture parts for high luminance included in said exposing aperture holes formed in said plurality of blades are set in such positions that the quantities of oblique incident light which are obtained from said high luminance exposing aperture parts and gradually increase accordingly as said blades are located farther away from the exposure surface are corrected to be equal to the amount of oblique incident light which is obtained from said high luminance exposing aperture part of one of said blades located nearest to the exposure surface.

3. A photographing device having a plurality of blades disposed one after another in an overlapping manner in the direction of an optical axis of a photo-taking lens, with an exposing aperture part for high luminance included in an exposing aperture hole formed in each of said blades, and performing exposure control for an exposure surface by driving and moving said blades relative to each other in the direction of traversing the optical axis, characterized in that:

shapes of said exposing aperture parts for high luminance included in said exposing aperture holes formed respectively in said blades are arranged to be smaller accordingly as said blades are located farther away from the exposure surface and wherein the exposing aperture holes are arranged to adjust an amount of light incident through said photo-taking lens.

4. A device according to claim 3, wherein the shapes of said high luminance exposing aperture parts of said exposing aperture holes formed in said blades are set respectively at such dimensions that the quantities of oblique incident light which are obtained from said high luminance exposing aperture parts and gradually increase accordingly as said blades are located farther away from the exposure surface are corrected to be equal to the quantity of oblique incident light which is obtained from said high luminance exposing aperture part of one of said blades located nearest to the exposure surface.