Single lens reflex camera

Details Single lens reflex camera Single lens reflex camera

1999-03-15

2001-02-06

Mathews, Alan A. (Department: 2851)

Photography

Single lens reflex camera

With mirror support or drive

C359S876000

Reexamination Certificate

active

06183142

ABSTRACT:

CROSS-REFERENCED APPLICATIONS
This application is based on Application No. HEI 10-67178 filed in Japan, the content of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a mirror device for a single lens reflex camera.
2. Description of the Related Art
FIGS. 1A and 1B
are center section views of a conventional single lens reflex camera with the photographic lens removed. In general, the mirror device of a single lens reflex camera is moved as indicated in
FIGS. 1A and 1B
in accordance with the operating state.
The mirror arrangement shown in
FIG. 1A
pertains to the state in preparation for optical exposure. A main mirror
10
directs the optical path of the photographic frame to a pentagonal prism
2
to allow the photographer to view the photographic frame through a finder
3
. At the same time, the luminous flux of the rangefinder area passes through the half mirror part of the main mirror
10
, and is directed to a rangefinder unit
4
via a sub-mirror
20
. Rangefinding calculations are executed based on the output of the rangefinding unit
4
.
On the other hand, the mirror disposition during optical exposure is shown in FIG.
1
B. When the main mirror
10
and the sub-mirror
20
are rotated upward to the retracted state outside the photographic optical path, exposure control is executed by a shutter
5
, so as to optically expose the photographic frame on a film
6
. At this time, the main mirror
10
is retracted to the pentagonal prism
2
side, and the sub-mirror
20
is retracted to a position covering the half-mirror area corresponding to the rangefinder area of the main mirror
10
, so as to prevent inverse incidence of light from the finder
3
into the optical exposure path.
The main mirror
10
and the sub-mirror
20
rotate via the operation illustrated in FIG.
2
. That is, a mirror holder
12
which supports the main mirror
10
is itself supported on a support shaft
8
so as to be rotatable relative to a mirror box, and move in rotation between the exposure preparation position A and the exposure position B indicated by arrow
92
. A sub-mirror holder
22
which supports the sub-mirror
20
is itself supported by a hinge
14
so as to be rotatable relative to the main mirror holder
12
, and move between the exposure preparation position A and the exposure position B via the hinge
14
together with the main mirror holder
12
, and rotates about the hinge
14
to the main mirror holder
12
side at the exposure position B.
A mirror drive mechanism such as, for example, the mechanism shown in
FIGS. 3A and 3B
is provided at the side of the mirror box to operate the main mirror
10
in the aforesaid manner.
When the main mirror
10
is set at the exposure preparation position, i.e., when the mirror is in the down position show in
FIG. 3A
, an overcharge spring
34
supported on a mirror drive lever
33
presses down on the drive portion
16
of the main mirror holder
12
, such that a force is exerted on the main mirror holder
12
in the mirror down direction (counter clockwise direction in the drawing) until the main mirror holder
12
is stopped by a stopper not shown in the drawing so as to be maintained in the exposure preparation position. Although the mirror drive lever
33
pivots about a support shaft
33
s in the mirror up direction via a mirror drive spring
35
, this pivoting is regulated by a mirror charge lever
36
.
When the main mirror
10
is set at the exposure position, i.e., set in the up position, shown in
FIG. 3B
, the mirror charge lever
36
is released and moved downward, and the mirror drive lever
33
is rotated in a counterclockwise direction in the drawing via a mirror drive spring
35
. At this time, the contact portion
33
a
of the mirror drive lever
33
presses upward on the drive portion
16
of the main mirror holder
12
so as to lift the mirror.
A mirror drive mechanism such as that shown in
FIGS. 4A and 4B
is provided to drive the sub-mirror
20
.
When the set at the exposure preparation position, i.e., when set in the mirror down position shown in
FIG. 4A
, a sub-mirror holder
22
supporting the sub-mirror
20
is rotated about a hinge
14
which functions as a rotating shaft relative to the main mirror holder
12
, such that the sub-mirror holder
22
is positioned so as to be open relative to the main mirror holder
12
. One end of a sub-mirror drive spring
15
is attached to connector
22
a
of the sub-mirror holder
22
, and the other end is attached to a connector
12
a
of the main mirror holder
12
. The movement of the sub-mirror holder
22
is regulated a guide shaft
9
fixedly attached to the mirror box. The sub-mirror drive spring
15
exerts a force on the sub-mirror
20
in a counterclockwise direction in the drawing, until the sub-mirror holder
22
is stopped by a stopper not shown in the illustration.
When the sub-mirror
20
is set at the exposure position, i.e., set in the mirror up position as shown in
FIG. 4B
, the sub-mirror holder
22
is guided by the guide shaft
9
of the mirror box to the position shown in the drawing. The sub-mirror drive spring
15
exerts a force on the sub-mirror
20
in a clockwise direction in the drawing, so as to be folded outside the photographic optical path together with the main mirror holder
12
.
As shown in
FIG. 6
, the respective exposure preparation positions of the main mirror
10
and the sub-mirror
20
are adjustable via the stoppers
18
and
28
provided in the mirror box. That is, a main mirror stopper
18
contacts the main mirror holder
12
which supports the main mirror
10
. The main mirror stopper
18
is an eccentric pin, which allows adjustment of the stopper position, i.e., the rotation angle, of the main mirror holder
12
by rotating the main mirror stopper
18
. A sub-mirror stopper
28
contacts the sub-mirror holder
22
which supports the sub-mirror
20
, and this stopper
28
is also an eccentric pin which allows adjustment in the same manner as described above.
In mirror devices of the aforesaid conventional construction, when the main mirror holder
12
is moved via adjustment by the main mirror stopper
18
, the angle of the sub-mirror also changes simultaneously therewith due to the movement of the hinge
14
functioning as the rotational axis of the sub-mirror holder
22
provided on the main mirror holder
12
. Furthermore, since the sub-mirror
20
is maintained relative to the mirror box by sub-mirror holder
22
through the main mirror holder
12
, there is a wide variation in the position of the sub-mirror
20
due to cumulative component errors. For this reason a complex adjustment mechanism is required to obtain the necessary positional adjustment operation for the sub-mirror
20
. Furthermore, after the position has been adjusted, the position (3-axis) of the rangefinding unit
4
must be adjusted, as indicated by arrows
90
and
91
in FIG.
1
A.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a mirror device for a single lens reflex camera which does not produce positional dislocation of the sub-mirror when the position of the main mirror is adjusted.
The present invention relates to a mirror device having a main mirror for directing luminous flux entering the photographic optical path to the outside of the photographic optical path, and a sub-mirror for directing luminous flux passing through a half-mirror forming part of the main mirror to a rangefinding optical unit. The main mirror and the sub-mirror are retractable to outside the photographic optical path. A sub-mirror holder which holds the sub-mirror is supported by a body of the device so as to be rotatable.
The mirror device for a single lens reflex camera may include a main mirror for directing luminous flux entering the photographic optical path to the outside of the photographic optical path, and a sub-mirror for directing luminous flux passing through a half-mirror forming part of the main mirror to a rangefinding optical unit. A retraction

Affiliated with

Also associated with

Rating

Single lens reflex camera does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Single lens reflex camera, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Single lens reflex camera will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2570006