US3700314A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Variable light transmitting filter for cameras
Assignee: Ampex Corp
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Filing: 1971-04-07
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Granted: 1972-10-24
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Expires: 1991-04-07
Abstract
Abstract A filter for permanent installation to extend the effective range of iris openings of a camera; the filter has light transmittance characteristics varying smoothly from low transmittance at the center to high transmittance at the periphery.
Inventors
- 👤 Edwin S Busby Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 22:26
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/20; G02B5/205; G03; G03B; G03B17/00; G03B17/02; G03B17/12
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
88 words
A variable light-transmitting filter combination, comprising: a mask having a variable area aperture formed therein and defined in part by a camera type circumferentially expandable and contractable iris mechanism; and a semi-transparent filter element covering said aperture; said filter element having a smoothly varying transmittance characteristic from point to point thereof; wherein said transmittance characteristic of said filter varies from a point of minimum light transmittance at the center of said filter and iris and increases smoothly radially outwardly for at least a central portion of the filter.
Claim 2
Dependent Claim
88 words
A variable light-transmitting filter combination, comprising: a mask having a variable area aperture formed therein and defined in part by a camera type circumferentially expandable and contractable iris mechanism; and a semi-transparent filter element covering said aperture; said filter element having a smoothly varying transmittance characteristic from point to point thereof; wherein said transmittance characteristic of said filter varies from a point of minimum light transmittance at the center of said filter and iris and increases smoothly radially outwardly for at least a central portion of the filter.
Claim 3
Dependent Claim
53 words
The combination recited in claim 1, wherein the radially outwardly increasing portions of said filter varies in accordance with the equation T RK, in which T is the transmittance expressed in percent of incident light passed, R is the radius from the center of the filter, and K is a chosen exponential value.
Claim 4
Dependent Claim
12 words
The combination recited in claim 2, wherein K is equal to 0.72.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-24 | 1976-04-24 | 1976-10-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-24 | 1980-04-24 | 1980-10-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-24 | 1984-04-24 | 1984-10-24 | $7700.00 | Window Closed / Lapsed |