Patent US4948238A successfully refreshed from Google Patents.
US4948238A
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US
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Optical projection system
Assignee: Panasonic Holdings Corp
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Filing: 1989-03-10
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Granted: 1990-08-14
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Expires: 2009-03-10
Abstract
Abstract A first lens, a second lens, means and a third lens means are arranged successively in a direction of travel of a ray. The first lens means each comprising a single lens element power. The second lens means has a predetermined negative refracting power. The third lens means has a predetermined positive refracting power. A fourth lens means consisting of a plurality of lens elements follows the third lens means in the direction of travel of the ray and has a predetermined positive refracting power. At least one surface of the first, second, third, and fourth lens elements is aspherical. The follwoing conditions (1), (2), and (3) are satisfied: 4f<f3<20f (1) 0.65<(f4/d34)<1.40 (2) 10f<R5 (3) where the character "f" denotes a focal length of the optical projection system, the character "f3"denotes a focal length of the third lens means, the character "f4" denotes a focal length of the lens group, the character "d34" denotes a distance between a rear principal point of the third lens means and a front principal point of the fourth lens, and the character "R5" denotes a radius of curvature of a front surface of the third lens means.
Inventors
- 👤 Nobuhiro Araki
- 👤 Takeo Sato
- 👤 Koichi Kawata
- 👤 Noboru Nomura
- 👤 Keisuke Koga
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 18:41
CPC Classifications
G; G02; G02B; G02B13/00; G02B13/18; G02B13/24
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
212 words
An optical projection system comprising: a first lens means, a second lens means, and a third lens means, each consisting of a single lens element, arranged successively in a direction of travel of a ray, the first lens means having a predetermined negative refracting power, the second lens means having a predetermined negative refracting power, the third lens means having a predetermined positive refracting power; a fourth lens means consisting of a plurality of lens elements which follows the third lens means in the direction of travel of the ray and which has a predetermined positive refracting power; wherein at least one surface of the first, second, third, and fourth lens elements is aspherical, and wherein the following conditions (1), (2) and (3) are satisfied: 4f<f3<20f (1) 0.65<(f4/d34)<1.40 (2) 10f<R5 (3) where the character "f" denotes a focal length of the optical projection system, the character "f3" denotes a focal length of the third lens means, the character "f4" denotes a focal length of the fourth lens means, the character "d34" denotes a distance between a rear principal point of the third lens means and a front principal point of the fourth lens means, and the character "R5" denotes a radius of curvature of a front surface of the third lens means.
Claim 2
Dependent Claim
212 words
An optical projection system comprising: a first lens means, a second lens means, and a third lens means, each consisting of a single lens element, arranged successively in a direction of travel of a ray, the first lens means having a predetermined negative refracting power, the second lens means having a predetermined negative refracting power, the third lens means having a predetermined positive refracting power; a fourth lens means consisting of a plurality of lens elements which follows the third lens means in the direction of travel of the ray and which has a predetermined positive refracting power; wherein at least one surface of the first, second, third, and fourth lens elements is aspherical, and wherein the following conditions (1), (2) and (3) are satisfied: 4f<f3<20f (1) 0.65<(f4/d34)<1.40 (2) 10f<R5 (3) where the character "f" denotes a focal length of the optical projection system, the character "f3" denotes a focal length of the third lens means, the character "f4" denotes a focal length of the fourth lens means, the character "d34" denotes a distance between a rear principal point of the third lens means and a front principal point of the fourth lens means, and the character "R5" denotes a radius of curvature of a front surface of the third lens means.
Claim 3
Dependent Claim
18 words
The optical projection system of claim 1 wherein the front surface of the third lens means is aspherical.
Claim 4
Dependent Claim
17 words
The optical projection system of claim 1 wherein the fourth lens elements have predetermined positive refracting powers.
Claim 5
Dependent Claim
243 words
An optical projection system comprising: a first lens means, a second lens means, and a third lens means, each consisting of a single lens element, arranged successively in a direction of travel of a ray, the first lens means having a predetermined negative refracting power, the second lens means having a predetermined negative refracting power, the third lens means having a predetermined positive refracting power; a fourth lens means consisting of a plurality of lens elements which follows the third lens means in the direction of travel of the ray and which has a predetermined positive refracting power; a fifth lens means consisting of a single lens element following the fourth lens means in the direction of travel of the ray and having a predetermined negative refracting power; wherein at least one surface of the first, second, third, fourth and fifth lens elements is aspherical, and wherein the following conditions (1), (2), and (3) are satisfied: 4f<f3<20f (1) 0.65<(f4/d34)<1.40 (2) 10f<R5 (3) where the character "f" denotes a focal length of the optical projection system, the character "f3" denotes a focal length of the third lens means, the character "f4" denotes a focal length of the fourth lens means, the character "d34" denotes a distance between a rear principal point of the third lens means and a front principal point of the fourth lens means, and the character "R5" denotes a radius of curvature of a front surface of the third lens means.
Claim 6
Dependent Claim
243 words
An optical projection system comprising: a first lens means, a second lens means, and a third lens means, each consisting of a single lens element, arranged successively in a direction of travel of a ray, the first lens means having a predetermined negative refracting power, the second lens means having a predetermined negative refracting power, the third lens means having a predetermined positive refracting power; a fourth lens means consisting of a plurality of lens elements which follows the third lens means in the direction of travel of the ray and which has a predetermined positive refracting power; a fifth lens means consisting of a single lens element following the fourth lens means in the direction of travel of the ray and having a predetermined negative refracting power; wherein at least one surface of the first, second, third, fourth and fifth lens elements is aspherical, and wherein the following conditions (1), (2), and (3) are satisfied: 4f<f3<20f (1) 0.65<(f4/d34)<1.40 (2) 10f<R5 (3) where the character "f" denotes a focal length of the optical projection system, the character "f3" denotes a focal length of the third lens means, the character "f4" denotes a focal length of the fourth lens means, the character "d34" denotes a distance between a rear principal point of the third lens means and a front principal point of the fourth lens means, and the character "R5" denotes a radius of curvature of a front surface of the third lens means.
Claim 7
Dependent Claim
18 words
The optical projection system of claim 4 wherein the front surface of the third lens means is aspherical.
Claim 8
Dependent Claim
17 words
The optical projection system of claim 4 wherein the fourth lens elements have predetermined positive refracting powers.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-08-13 | 1994-02-12 | 1994-08-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-08-13 | 1998-02-12 | 1998-08-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-08-13 | 2002-02-12 | 2002-08-14 | $7700.00 | Window Closed / Lapsed |