US4828374A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Albada type inverted Galileo finder
Assignee: Konica Minolta Inc
•
Filing: 1988-02-18
•
Granted: 1989-05-09
•
Expires: 2008-02-18
Abstract
Abstract An Albada type inverted Galileo finder which is suitable foruse with a compace lens shutter camera, which is small in size, and which is visible without occurrence of any ghost not only in an object but a finder frame. If lenses are disposed in order of negative, positive and positive from the side of an object and a reflecting surface of an Albada system is a surface on the side of the object of a positive lens, a finder which involves no ghost and is advantageous for correction of aberrations can be obtained. Furthermore, if the on-the-axis thickness of each lens is restricted to thereby provide a plastic lens, precision of molding can be improved.
Inventors
- 👤 Akira Ishisaka
- 👤 Kohei Ota
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 04:34
CPC Classifications
G; G02; G02B; G02B27/00; G02B27/0018; G02B13/00; G02B13/18; G02B23/00; G02B23/14; G03; G03B; G03B13/00; G03B13/02; G03B13/06; G03B13/08
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
88 words
An Albada type inverted Galileo finder comprising: a plurality of lenses, one of said plurality of lenses having a positive refractory power whose surface on the object side is a reflecting surface of an Albada system, said finder conforming to the following conditions: ##EQU13## where L=the on-the-axis length of the finder from the surface closest to the object of the finder system to the surface closest to the pupil; di=the on-the-axis thickness of the ith lens from the object side; and m=the number of lenses in the finder.
Claim 2
Dependent Claim
88 words
An Albada type inverted Galileo finder comprising: a plurality of lenses, one of said plurality of lenses having a positive refractory power whose surface on the object side is a reflecting surface of an Albada system, said finder conforming to the following conditions: ##EQU13## where L=the on-the-axis length of the finder from the surface closest to the object of the finder system to the surface closest to the pupil; di=the on-the-axis thickness of the ith lens from the object side; and m=the number of lenses in the finder.
Claim 3
Dependent Claim
27 words
An Albada type inverted Galileo finder according wherein said finder is fulfilled with 2/3L<C.sub.1 '<1/0.2L where C.sub.1 ' is the curvature of an Albada system reflecting surface.
Claim 4
Dependent Claim
27 words
An Albada type inverted Galileo finder according wherein said finder is fulfilled with 2/3L<C.sub.1 '<1/0.2L where C.sub.1 ' is the curvature of an Albada system reflecting surface.
Claim 5
Dependent Claim
16 words
An Albada type inverted Galileo finder according to claim 1, wherein said finder is fulfilled with
Claim 6
Dependent Claim
68 words
-2. 0 mm<ΔX 1 (0.3L)<-0.005 mm if the surface of on the pupil side of the object lens is an aspherical surface, a value in a height from an optical axis y=0.3L of a difference ΔX between (said) aspherical surface and a reference spherical surface is represented by ##EQU14## K: the coefficient of the secondary curved surface Aj: the coefficient of the aspherical surface C=C*+2A 2 (paraxial curvature).
Claim 7
Dependent Claim
68 words
-2. 0 mm<ΔX 1 (0.3L)<-0.005 mm if the surface of on the pupil side of the object lens is an aspherical surface, a value in a height from an optical axis y=0.3L of a difference ΔX between (said) aspherical surface and a reference spherical surface is represented by ##EQU14## K: the coefficient of the secondary curved surface Aj: the coefficient of the aspherical surface C=C*+2A 2 (paraxial curvature).
Claim 8
Dependent Claim
69 words
An Albada type inverted Galileo finder according to claim 1, which has aspherical surfaces, the total value in a height from an optical axis y=0.3L of a difference X between said aspherical surface and the spherical surface is fulfilled with ##EQU15## where ΔXi(0.3L): a value of deviation from a reference spherical surface of ith aspherical surface from the object side at the height of 0.3L from the optical axis.
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) | 1992-05-08 | 1992-11-07 | 1993-05-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-05-08 | 1996-11-07 | 1997-05-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-05-08 | 2000-11-07 | 2001-05-09 | $7700.00 | Window Closed / Lapsed |