Patent US3658415A successfully refreshed from Google Patents.
US3658415A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Off axis low volume microform projector
Assignee: MICRODISPLAY SYSTEMS Inc
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Filing: 1970-09-14
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Granted: 1972-04-25
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Expires: 1990-09-14
Abstract
Abstract A compact film projector in which a wide angle lens is used for focusing the object on a screen, but considerably less than all of the available wide angle lens field is used. The cubic volume of the system is greatly reduced by discarding a portion of the field. A reflecting prism incorporated in the lens assembly and a reflecting mirror as a part of the condensing lens system make the projector even more compact.
Inventors
- 👤 John R Miles
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 10:49
CPC Classifications
G; G03; G03B; G03B21/00; G03B21/10; G03B21/11
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
139 words
A compact transparent medium projecting device comprising a hollow housing having an apertured top, a bottom, spaced side walls and a front and back wall, a translucent screen member carried in the housing top aperture, a light source, a condenser to receive light from the light source and direct it through a transparent medium, a wide angle projection lens assembly having an axis and positioned to receive off-axis and substantially on one side of the axis light passing through the transparent medium, a prism within the projection lens assembly to change the direction of light path entering the said projection lens, a top mirror within the housing to receive the light coming from the projection lens, a bottom mirror to receive the light reflected from the top mirror and direct it upon the inner surface of the screen member.
Claim 2
Dependent Claim
139 words
A compact transparent medium projecting device comprising a hollow housing having an apertured top, a bottom, spaced side walls and a front and back wall, a translucent screen member carried in the housing top aperture, a light source, a condenser to receive light from the light source and direct it through a transparent medium, a wide angle projection lens assembly having an axis and positioned to receive off-axis and substantially on one side of the axis light passing through the transparent medium, a prism within the projection lens assembly to change the direction of light path entering the said projection lens, a top mirror within the housing to receive the light coming from the projection lens, a bottom mirror to receive the light reflected from the top mirror and direct it upon the inner surface of the screen member.
Claim 3
Dependent Claim
32 words
A device according to claim 1 in which the prism is a totally reflecting prism and not more than 60 percent of the field of the wide angle projection lens is used.
Claim 4
Dependent Claim
14 words
A device according to claim 1 in which the condenser includes a plane mirror.
Claim 5
Dependent Claim
29 words
A device according to claim 1 in which the apertured portion of the housing top is inclined at an angle to receive the light coming from the bottom mirror.
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) | 1975-04-25 | 1975-10-25 | 1976-04-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-25 | 1979-10-25 | 1980-04-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-25 | 1983-10-25 | 1984-04-25 | $7700.00 | Window Closed / Lapsed |