Optical: systems and elements – Image stabilization – By movable refractive structure
Reexamination Certificate
1998-12-30
2001-05-01
Nguyen, Thong (Department: 2872)
Optical: systems and elements
Image stabilization
By movable refractive structure
C359S554000, C359S407000
Reexamination Certificate
active
06226123
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an optical system for an observing equipment such as a binocular or a terrestrial telescope that has an image-vibration compensation system.
Recently, binoculars provided with image-vibration compensation systems for preventing vibration of observed image due to a hand-held shake of a user have been developed. Japanese Laid Open Publication No. HEI 6-43365 discloses an image-vibration compensation system of a binocular that employs a variable angle prism for each of telescopic optical systems of the binocular. A variable angle prism is located between an objective lens and an erecting system. When the optical system vibrates due to a hand-held shake of a user, the vertex angle of the variable angle prism is controlled to stabilize the image.
In such a construction, however, since the variable angle prism is located in the convergent light, if the vertex angle of the prism is changed, decentering coma occurs largely.
Another example of the image-vibration compensation system for binoculars is disclosed in Japanese Laid Open Publication No. HEI 6-308431. The binocular in the publication employs a compensation device that is attached in front of the objective optical systems of the binocular. Since the first lens of the objective optical system has the largest diameter in the telescopic optical system, in general, and the device is arranged in front of the first lenses, the device becomes large in size, which increases the size of the binocular.
SUMMARY OF THE INVENTION
it is therefore an object of the present invention to provide an optical system of an observing equipment having image-vibration compensation system, which can reduce decentering coma during an image-vibration compensation, and is compact in size.
For the above object, according to the present invention, there is provided an optical system of an observing equipment having an image-vibration compensation system. The optical system includes an objective optical system that includes:
a first lens group having positive refractive power;
a second lens group having negative refractive power; and
a third lens group having positive refractive power, the lens groups being arranged in that order from an object side,
wherein at least one of the second and third lens groups is a compensation lens group that is movable in a direction perpendicular to an optical axis of the objective optical system to compensate a vibration of an image due to a hand-held shake, and
wherein conditions (1) and (2) are satisfied:
(1) 0.1<d
12
/f
0
(2) 0.7<f
0
/f
1
<3.0
where,
d
12
is a distance between the first lens group and the second lens group,
f
0
is the focal length of the objective optical system, that is, f
0
is the resultant focal length of the first, second and third lens groups, and
f
1
is the focal length of the first lens group.
With this construction, since the compensation lens groups are parts of the objective optical system located at the image side in the objective optical system, the size of the compensation element becomes smaller than the conventional element which is located at the object side of the objective optical system.
In the specific embodiment where the second and third lens groups are the compensation lens groups, the following condition (3) is satisfied:
(3)−0.95<(&phgr;
2
−&phgr;
1
)/(&phgr;
3
−&phgr;
2
)<−1.05
where,
&phgr;
1
is a refractive power of the first lens group,
&phgr;
2
is a resultant refractive power of the first lens group and the second lens group, and
&phgr;
3
is a resultant refractive power of the first through third lens groups.
In the case where only the second lens group is movable in a direction perpendicular to the optical axis, it is desirable to satisfy condition (4). When only the third lens group is movable, it is desirable to satisfy condition (5). In the conditions, tan 1° equals to 0.0174551.
(4) 0.5<|tan 1°/(&phgr;
2
−&phgr;
1
)|<5.0 (unit: mm)
(5) 0.5<|tan 1°/(&phgr;
3
−&phgr;
2
)|<5.0 (unit: mm)
Further, if both the second and third lens groups are the compensation lens groups, it is desirable to satisfy the conditions (4) and (5). In such a case, the second lens group may be movable along a first direction in a plane perpendicular to the optical axis and the third lens group may be movable along a second direction that intersects the first direction at right angle in the plane.
In the preferred embodiments, the first lens group consists of a positive lens and a negative lens, the second lens group consists of only one negative lens or a combination of a negative lens and a positive lens, and the third lens group consists of a positive lens.
Optionally, the optical system may further include an eyepiece through which a user observes an image formed by the objective optical system. The optical system may still further include erecting system that is located between the objective optical system and the eyepiece.
REFERENCES:
patent: 4974950 (1990-12-01), Yamazaki et al.
patent: 5461513 (1995-10-01), Maruyama
patent: 5490014 (1996-02-01), Suzuki
patent: 5530594 (1996-06-01), Shibayama
patent: 5694244 (1997-12-01), Abe et al.
patent: 5754339 (1998-05-01), Kanai et al.
patent: 5768016 (1998-06-01), Kanbara
patent: 5842054 (1998-11-01), Suzuki et al.
patent: 61-156019 (1986-07-01), None
patent: 4-318510 (1992-11-01), None
patent: 6-43365 (1994-02-01), None
patent: 6308431 (1994-11-01), None
patent: 10-20213 (1998-01-01), None
patent: 10186228 (1998-07-01), None
Kanai Moriyasu
Maruyama Koichi
Asahi Kogyo Kabusiki Kaisha
Greenblum & Bernstein P.L.C.
Nguyen Thong
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