Eye cup moving mechanism of optical device

Details Eye cup moving mechanism of optical device Eye cup moving mechanism of optical device

2001-06-08

2003-06-03

Schwartz, Jordan M. (Department: 2873)

Optical: systems and elements

Lens

With support

C359S822000, C359S425000, C359S821000, C359S819000

Reexamination Certificate

active

06574056

ABSTRACT:

INCORPORATION BY REFERENCE
The disclosure of the following priority application is herein incorporated by reference:
Japanese Patent Application No. 2000-175186 filed Jun. 12, 2000
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an eye cup moving mechanism of an optical device having an eye cup, such as a telescope, a binocular or a microscope.
2. Description of the Related Art
The eye cup of an optical device, which is mounted at the eyepiece unit, is moved along the direction of the optical axis of the eyepiece lens to offer a comfortable visual field to both a user wearing glasses and a user who does not wear glasses. An eye cup in the prior art is rotated around the optical axis of the eyepiece lens to travel along the direction of the optical axis, and its traveling distance is regulated by a cam mechanism.
FIG. 5
is a longitudinal sectional view of the structure adopted in an eye cup moving mechanism in the prior art. An eye cup
20
is constituted by securing an eye cup cover
11
around the external circumference of an eyepiece outer casing
12
. The eyepiece outer casing
12
is formed in a cylindrical shape, and its internal circumferential surface is allowed to slide against the external circumferential surface of an eyepiece lens holding barrel
14
. The external circumferential surface “s” of the eyepiece lens holding barrel
14
is formed to extend straight along the direction of the optical axis. With the eyepiece outer casing
12
moving relative to the eyepiece lens holding barrel
14
along the external circumferential surface “s”, the distance between an eye cup front end
20
a
and the outer end surface of the eyepiece lens is varied.
In
FIG. 5
, the eye cup front end
20
a
is at position d
1
which sets the eye cup in an driven-out state. When the eye cup front end
20
a
is at position d
2
indicated by the dotted line in the figure, the eye cup is in a driven-in state. The eye cup front end is set at position d
1
or d
2
by employing a cam mechanism constituted of camshafts
15
a
and
15
b
provided at the eyepiece lens holding barrel
14
and a cam groove (not shown) formed at the eyepiece outer casing
12
. It is to be noted that the eyepiece lens holding barrel
14
normally holds a plurality of eyepiece lenses and is mounted at the optical device main unit on the objective lens side.
FIG. 6A
is a top view,
FIG. 6B
is a side elevation,
FIG. 6C
is a bottom view and
FIG. 6D
is a side elevation of the half cylinder obtained by slicing the top view in FIG.
6
A through line X—X, all provided to illustrate the structure of the eyepiece outer casing
12
in the prior art.
Simply put, the eyepiece outer casing
12
is a cylinder having two cam grooves
16
a
and
16
b
set at 180° relative to each other at the cylinder surface. The camshafts
15
a
and
15
b
in
FIG. 5
engage with the two cam grooves
16
a
and
16
b
respectively. When the camshafts
15
a
and
15
b
are each at position d
1
, the eye cup
20
is set in a driven-out state, whereas when the camshafts
15
a
and
15
b
are at position d
2
, the eye cup
20
is set in a driven-in state. When the eye cup
20
is retained at either position d
1
or d
2
, the camshafts
15
a
and
15
b
are each pressed at an end of the cam groove
16
a
or
16
b.
In other words, the movement of the eye cup is regulated by the cam mechanism.
When the camshafts are retained to set the position of the eye cup, the camshafts are pressed against the cam grooves, and thus, the greatest force is applied where the camshafts are mounted at the eyepiece holding barrel. In an optical device having a compact eyepiece unit, in particular, small camshafts that are mounted (e.g., screwed in) over a small screwing diameter are naturally used.
The eye cup cover for the eye cup is often constituted of rubber, and when it is rotated, a large moment is generated to result in an impact force manifesting upon the camshafts becoming pressed against the ends (position d
1
or d
2
) of the cam grooves. In a worst case, the areas over which camshafts are mounted that are most greatly affected by the impact force may become damaged. The ends of the cam grooves, too, are subject to the impact force.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an eye cup moving mechanism that prevents camshafts and cam grooves from becoming damaged even when a great force is applied.
In order to attain the above object, an eye cup moving mechanism of an optical device according to the present invention, comprises: an eyepiece lens holding barrel that houses and holds an eyepiece lens; an eyepiece outer casing that is capable of sliding against an external circumferential portion of the eyepiece lens holding barrel; and an eye cup cover provided at the eyepiece outer casing. The eyepiece lens holding barrel includes a first regulating member provided at the external circumferential portion thereof; and the eyepiece outer casing includes a second regulating member that comes in contact with the first regulating member to regulate a movement of the eye cup cover along an optical axis of the eyepiece lens.
In this eye cup moving mechanism of an optical device, it is preferred that the eyepiece lens holding barrel and the eyepiece outer casing are relatively moved along an optical axis of the eyepiece lens by a cam mechanism constituted of a cam shaft provided at either the eyepiece lens holding barrel or the eyepiece outer casing and a cam groove formed at either the eyepiece lens holding barrel or the eyepiece outer casing at which the camshaft is not provided; and the first regulating member at the eyepiece lens holding barrel and the second regulating member at the eyepiece outer casing are provided so as to come into contact with each other before an end of the cam groove comes in contact with the camshaft.
Also, it is preferred that the first regulating member comprises a third regulating member and a fourth regulating member; the second regulating member comprises a fifth regulating member and a sixth regulating member; the third regulating member at the eyepiece lens holding barrel and the fifth regulating member at the eyepiece outer casing come in contact with each other when the eye cup cover is driven-out furthest toward a user; and the fourth regulating member at the eyepiece lens holding barrel and the sixth regulating member at the eyepiece outer casing come in contact with each other when the eye cup cover is driven in furthest from the user. In this case, it is preferred that the third regulating member and fourth regulating member are formed so as to project outward at the external circumferential portion of the eyepiece lens holding barrel; the fifth regulating member is formed so as to project inward at an internal circumferential portion of the eyepiece outer casing; and the sixth regulating member is constituted of an end of the eyepiece outer casing located on a side opposite from the user. Furthermore, it is preferred that a cutting portion is provided at a portion of at least either the third regulating member or the fifth regulating member so as to ensure that the third regulating member and the fifth regulating member do not come in contact with each other.
Also, it is preferred that the first regulating member at the eyepiece lens holding barrel and the second regulating member at the eyepiece outer casing come in contact with each other when the eye cup cover is driven-out furthest toward a user. In this case, it is preferred that the first regulating member is formed so as to project outward at the external circumferential portion of the eyepiece lens holding barrel; and the second regulating member is formed so as to project inward at an internal circumferential portion of the eyepiece outer casing. Furthermore, it is preferred that a cutting portion is provided at a portion of at least either the first regulating member or the second regulating member so as to ensure that the first regulating member and the second regulating member do not come in

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