US3877797A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical filter combination for improving color discrimination
Assignee: Philips North America LLC
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Filing: 1973-10-23
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Granted: 1975-04-15
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Expires: 1993-10-23
Abstract
Abstract Optical filter combination removes two selected bands of light in order to improve the observed color discrimination between different colored objects. One of the filtered bands includes radiations of a wavelength of 580 nm and the other of the filtered bands includes radiations of a wavelength of 490 nm. Each of the filtered bands is preferably from 5 nm to 55 nm wide although the bands can be widened to 80 nm if desired.
Inventors
- 👤 Jr William A Thornton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 06:20
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/20; G02B5/208; G02B5/22; G02C; G02C7/00; G02C7/10; G02C7/104; G02C2202/00; G02C2202/16
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
126 words
An optical filter combination which, when interposed in a light path of illuminating radiations to alter at least one of (a) the illuminating radiations generated by a light source and (b) the object-reflected radiations ultimately received by the viewer''s eye, will enhance the color discrimination which is observed between objects of different colors, said filter consisting of two essential filtering means, one of said essential filtering means removing from the light path a selected band of radiations which includes 580 nm radiations, and the other of said essential filtering means removing from the light path a selected band of radiations which includes 490 nm radiations and the bandwidth of the radiations removed by each of said essential filtering means being from 5 nm to 80 nm.
Claim 2
Dependent Claim
126 words
An optical filter combination which, when interposed in a light path of illuminating radiations to alter at least one of (a) the illuminating radiations generated by a light source and (b) the object-reflected radiations ultimately received by the viewer''s eye, will enhance the color discrimination which is observed between objects of different colors, said filter consisting of two essential filtering means, one of said essential filtering means removing from the light path a selected band of radiations which includes 580 nm radiations, and the other of said essential filtering means removing from the light path a selected band of radiations which includes 490 nm radiations and the bandwidth of the radiations removed by each of said essential filtering means being from 5 nm to 80 nm.
Claim 3
Dependent Claim
113 words
An optical filter combination which, when interposed between at least one of (a) viewed illuminated objects of different colors and the viewer, and (b) viewed illuminated objects of different colors and the light source which illuminates such objects, will enhance the apparent color discrimination between the viewed illuminated objects, said filter consisting of two essential filtering means, one of said essential filtering means absorbing a selected band of radiations centered at about 580 nm, and the other of said essential filtering means absorbing a selected band of radiations centered at about 490 nm, and the bandwidth of radiations absorbed by each of said essential filtering means being from 5 nm to 55 nm.
Claim 4
Dependent Claim
113 words
An optical filter combination which, when interposed between at least one of (a) viewed illuminated objects of different colors and the viewer, and (b) viewed illuminated objects of different colors and the light source which illuminates such objects, will enhance the apparent color discrimination between the viewed illuminated objects, said filter consisting of two essential filtering means, one of said essential filtering means absorbing a selected band of radiations centered at about 580 nm, and the other of said essential filtering means absorbing a selected band of radiations centered at about 490 nm, and the bandwidth of radiations absorbed by each of said essential filtering means being from 5 nm to 55 nm.
Claim 5
Dependent Claim
56 words
The optical filter combination as specified in claim 2, wherein said one filter means comprises didymium galss having a thickness of from about 0.5 mm to about 6 mm, and said other filter means comprises platinum tetraphenylporphyrin chelate film carried on said glass and having a thickness of from about 8 microns to about 300 microns.
Claim 6
Dependent Claim
27 words
The optical filter combination as specified in claim 3, wherein said filter combination is conformed as lens means to be fitted to the eyes of the observer.
References Cited (Backward Citations)
US1222049A
Cited
US3013114A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-14 | 1978-10-14 | 1979-04-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-14 | 1982-10-14 | 1983-04-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-14 | 1986-10-14 | 1987-04-15 | $7700.00 | Window Closed / Lapsed |