US 6,445,887 B1 · Viewfinder for camera with adjustable diopter

Abstract

A viewfinder for a camera with an adjustable diopter includes an objective lens and an eyepiece lens each having an optical axis extending parallel to a longitudinal axis of the camera. Light rays from the objective lens are reflected by a mirror and directed in one direction parallel to a transverse axis of the camera onto a focusing screen to form an object image. A first triangular prism receives light rays from the object image and reflects and directs the received light rays in opposite direction parallel to the transverse axis. A second triangular prism receives light rays from the first prism and reflects and directs the received light rays in the direction parallel to the longitudinal axis and toward the eyepiece lens. The first prism is supported and guided for linear displacement along the transverse axis, while the second prism is fixed to the body frame of the camera. A control knob operable by the camera operator is interconnected with the first prism through an interconnection mechanism composed of a two-arm lever and a spring cooperating with the lever. The interconnection mechanism responds to the operation of the control knob by causing linear displacement of the first prism along the transverse axis so as to change optical distance between the focusing screen and the eyepiece lens to achieve adjustment in diopter of the viewfinder.

Claims25

Dependent claims

A viewfinder for a camera with an adjustable diopter, said camera having a body frame and a taking lens, said taking lens having an optical axis which defines a longitudinal axis of said camera, said viewfinder comprising:

an objective lens mounted on said body frame and having an optical axis extending parallel to said longitudinal axis;
an eyepiece lens mounted on said body frame and having an optical axis extending parallel to said longitudinal axis;
a focusing screen mounted on said body frame and having a surface on which an object image is formed through said objective lens;
a light-rays-directing optical system mounted on said body frame, for causing light rays from said object image to be directed in a first direction parallel to a predefined transverse axis extending transversely with respect to said longitudinal axis;
a first reflective optical element for receiving light rays from said object image and reflecting and directing the received light rays in a second direction opposite to said first direction parallel to said transverse axis;
a first mechanism for supporting and guiding said first reflective optical element for linear displacement relative to said body frame and along said transverse axis;
a second reflective optical element mounted on said body frame for receiving light rays from said first reflective optical element and reflecting and directing the received light rays in a direction parallel to said longitudinal axis and toward said eyepiece lens;
a control knob provided for operation by a camera operator;
and
a second mechanism for responding to operation of said control knob by causing linear displacement of said first reflective optical element along said transverse axis so as to change optical distance between said focusing screen and said eyepiece lens to achieve adjustment in diopter of said viewfinder.

7 more elements

A diopter adjustment mechanism for use in a viewfinder of a camera, wherein the viewfinder comprises a plurality of optical elements including a movable optical element, and adjustment of a diopter of the viewfinder is achieved by liner displacement of said movable optical element along a predefined axis, said diopter adjustment mechanism comprising:

an optical element holder having a recess for receiving and holding said movable optical element;
a first mechanism provided on said optical element holder, for supporting and guiding said movable optical element for linear displacement along said axis;
a control knob provided for operation by a camera operator and supported for linear displacement;
and
a second mechanism for responding to operation of said control knob by causing linear displacement of said movable optical element along said axis so as to achieve adjustment of diopter of said viewfinder,
said second mechanism comprising:
a two-arm lever mounted on said optical element holder for pivotal movement and having first and second arms in engagement with said control knob and said movable optical element, respectively;
and
a spring mounted on said optical element holder and normally urging said movable optical element so as to maintain engagement between said first arm and said control knob and engagement between said second arm and said movable optical element without any backlash in each engagement.

6 more elements

A diopter adjustment mechanism for use in a viewfinder of a camera having a photographing lens with an optical axis which defines a longitudinal axis of the camera, wherein the viewfinder comprises a plurality of optical elements including a movable optical element, and adjustment of a diopter of the viewfinder is achieved by linear displacement of said movable optical element, said diopter adjustment mechanism comprising:

an optical element holder having a recess for receiving and holding said movable optical element;
a first mechanism provided on said optical element holder, that supports and guides said movable optical element for linear displacement along an axis extending transversely with respect to said longitudinal axis;
a control knob provided for operation by a camera operator;
and
a second mechanism that responds to operation of said control knob by causing linear displacement of said movable optical element along said transverse axis so as to achieve adjustment of diopter of said viewfinder.

2 more elements

Dependencies are inferred from the claim text.

Viewfinder for camera with adjustable diopter

Life of this patent

Viewfinder for camera with adjustable diopter

Life of this patent

Abstract

Claims25