US3623802A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Overhead projector
Assignee: Ernst Leitz Wetzlar GmbH
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Filing: 1969-03-14
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Granted: 1971-11-30
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Expires: 1989-03-14
Abstract
Abstract In the image-forming bundle of light rays of an overhead projector at least one further objective is arranged in addition to the projecting objective, which further objective serves as an intermediate optical system. Reflecting means are provided in the path of the light rays; and the objectives and the reflecting means are mounted structurally separate from the table which carries the supporting plate for the writing foil so that the view for the writer and for the audience is not obstructed.
Inventors
- 👤 Erwin Hubner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 04:21
CPC Classifications
G; G03; G03B; G03B21/00; G03B21/132
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
220 words
A projection system for use in a room bounded by walls, a floor and a ceiling, a platform located at one end of said room, a projection screen mounted on the wall adjacent said platform, image-forming means including a supporting plate, a writing foil disposed above said supporting plate, said image-forming means being located on said platform adjacent said projection screen for projection therethrough onto said screen of an image on said image-forming means, said projection system comprising in combination means for illuminating including a light source arranged on one side of said writing foil, a first objective for projecting arranged on the other side of said writing foil, the rays from said light source passing through said writing foil and as image-forming rays through said first objective, a second objective disposed between said first objective and said writing foil in the path of the image-forming rays, said second objective serving as an intermediate system by producing an intermediate image plane, at least one of said objectives being located outside the bounds of said room, at least one of said walls, floor or ceiling having apertures in the path of said image-forming rays whereby the image-forming rays pass through the apertures, and reflecting means disposed in the path of the image-forming rays between the writing foil and said projection screen.
Claim 2
Dependent Claim
220 words
A projection system for use in a room bounded by walls, a floor and a ceiling, a platform located at one end of said room, a projection screen mounted on the wall adjacent said platform, image-forming means including a supporting plate, a writing foil disposed above said supporting plate, said image-forming means being located on said platform adjacent said projection screen for projection therethrough onto said screen of an image on said image-forming means, said projection system comprising in combination means for illuminating including a light source arranged on one side of said writing foil, a first objective for projecting arranged on the other side of said writing foil, the rays from said light source passing through said writing foil and as image-forming rays through said first objective, a second objective disposed between said first objective and said writing foil in the path of the image-forming rays, said second objective serving as an intermediate system by producing an intermediate image plane, at least one of said objectives being located outside the bounds of said room, at least one of said walls, floor or ceiling having apertures in the path of said image-forming rays whereby the image-forming rays pass through the apertures, and reflecting means disposed in the path of the image-forming rays between the writing foil and said projection screen.
Claim 3
Dependent Claim
39 words
The projection system as defined in claim 1, wherein said objectives have an object distance of the same order as the height of the ceiling from the floor of said room and therefore have a correspondingly long focal distance.
Claim 4
Dependent Claim
45 words
The projection system of claim 1, wherein said second objective is arranged to produce an image of said writing foil into said intermediate image plane, the image in said intermediate plane and said writing foil having a ratio in relation to their dimensions of 1:1.
Claim 5
Dependent Claim
31 words
The projection system of claim 1, wherein at least one of said objectives in the path of said imaging rays is disposed In the vicinity of the ceiling of the room.
Claim 6
Dependent Claim
17 words
The projection system of claim 1, wherein said image-forming means includes holding means for holding transparent slides.
Claim 7
Dependent Claim
57 words
The projection system as defined in claim 1, wherein said means for illuminating is disposed above the supporting plate for the writing foil at such an angle that the optical axis of the rays passing through said supporting plate in inclined with respect to said supporting plate so as to produce a glare-free zone facing the writer.
Claim 8
Dependent Claim
31 words
The projection system as defined in claim 1, and further comprising an objective incorporated in said means for illuminating in addition to the light source, a mirror and a condenser lens.
Claim 9
Dependent Claim
33 words
The projection system as defined in claim 1, wherein in the image plane of one of said objectives, a field lens is disposed, said field lens serving as an additional object support surface.
Claim 10
Dependent Claim
26 words
The projection system as defined in claim 1, wherein an episcope is disposed in one of said intermediate image planes and all objectives lenses are aligned.
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) | 1974-11-29 | 1975-05-31 | 1975-11-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-29 | 1979-05-31 | 1979-11-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-29 | 1983-05-31 | 1983-11-30 | $7700.00 | Window Closed / Lapsed |