US4178611A
Expired / Lapsed
US
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Optical low pass filter
Assignee: Minolta Co Ltd
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Filing: 1978-03-22
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Granted: 1979-12-11
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Expires: 1998-03-22
Abstract
Abstract An optical low pass filter adapted for use in a single or double tube color television camera provided with an optical system including a color encoding filter for obtaining color or chrominance signals having the spatial frequency in a particular band. The low pass filter serves to cut off the high spatial frequency components of the image or luminance signals to eliminate the crosstalk between the chrominance and luminance signals. The low pass filter according to the present invention is a phase grating filter having the triangular-wave cross-sectional configuration, of which height is in a range given by a mathematical description.
Inventors
- 👤 Yukio Okano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 22:24
CPC Classifications
G; G02; G02B; G02B27/00; G02B27/42; G02B27/46; H; H04; H04N; H04N23/00; H04N23/10
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
151 words
In an optical system for a color television camera system including a spatial color encoding filter disposed in the light path of said optical system and serving to modulate at least two color images, the optical system comprising a photoelectric converting member for generating electrical signals corresponding to said images, an objective lens disposed in front of said photoelectric converting member to focus an image of an object thereon, and a phase grating filter member disposed between the object and said photoelectric converting member and having the configuration of a triangular wave in cross section taken along at least one direction, in which the height, d of the triangular wave is within a range defined by the following formula: ##EQU4## wherein n=refractive index of the filter material, n'=refractive index of the medium bordering the surface of the grating, and λ=wave length of the light affected by passing through the filter member.
Claim 2
Dependent Claim
151 words
In an optical system for a color television camera system including a spatial color encoding filter disposed in the light path of said optical system and serving to modulate at least two color images, the optical system comprising a photoelectric converting member for generating electrical signals corresponding to said images, an objective lens disposed in front of said photoelectric converting member to focus an image of an object thereon, and a phase grating filter member disposed between the object and said photoelectric converting member and having the configuration of a triangular wave in cross section taken along at least one direction, in which the height, d of the triangular wave is within a range defined by the following formula: ##EQU4## wherein n=refractive index of the filter material, n'=refractive index of the medium bordering the surface of the grating, and λ=wave length of the light affected by passing through the filter member.
Claim 3
Dependent Claim
28 words
An optical system as in claim 1, wherein the ratio K of widthes of adjacent side surfaces of each rectangle in the wave is given as follows: 0.5≦K≦2.0.
Claim 4
Dependent Claim
27 words
An optical system as in claim 1 wherein the phase grating is one dimensional with the ridge and valley portions of the grating having a curvilinear configuration.
Claim 5
Dependent Claim
15 words
An optical system as in claim 2 or 3 wherein the filter member is transparent.
Claim 6
Dependent Claim
33 words
An optical system as in claim 1 further comprising a prism member disposed between the objective and the photoelectric conventing member and having an output surface to which said filter member is cemented.
Claim 7
Dependent Claim
15 words
An optical low pass filter as in claim 1 wherein the phase grating is two-dimensional.
Claim 8
Dependent Claim
20 words
An optical low pass filter as in claim 1 wherein the respective sides of the triangular wave grating are asymmetrical.
Claim 9
Dependent Claim
97 words
In a phase grating type optical low pass filter for use in a single or double tube color television camera, the improvement comprising an optical low pass filter having a triangular-wave shape in cross section taken along at least one direction, the height, d, of the triangular wave being selected from a range given by the following formula: ##EQU5## wherein n is the refractive index of the filter material, n' is the refractive index of the medium bordering on the surface of the grating, and λ is the wave length of the light affected by the filter.
Claim 10
Dependent Claim
97 words
In a phase grating type optical low pass filter for use in a single or double tube color television camera, the improvement comprising an optical low pass filter having a triangular-wave shape in cross section taken along at least one direction, the height, d, of the triangular wave being selected from a range given by the following formula: ##EQU5## wherein n is the refractive index of the filter material, n' is the refractive index of the medium bordering on the surface of the grating, and λ is the wave length of the light affected by the filter.
Claim 11
Dependent Claim
18 words
An optical low pass filter as in claim 8 wherein each triangle in the triangular wave is symmetric.
Claim 12
Dependent Claim
31 words
An optical low pass filter as in claim 8 wherein the ratio K of widths of adjacent sides of the triangular wave is selected from a range given as follows: 0.5≦K≦2.0.
Claim 13
Dependent Claim
22 words
An optical low pass filter as in claim 8 wherein the filter is transparent, with the light to be affected passing therethrough.
Claim 14
Dependent Claim
44 words
An optical low pass filter as in claim 8 wherein surfaces of the triangular wave grating are coated with a light refractive material and the height, d, of the triangular wave is one-half the value of that set forth for a transparent filter material.
References Cited (Backward Citations)
US3821795A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-12-10 | 1983-06-11 | 1983-12-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-12-10 | 1987-06-11 | 1987-12-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-12-10 | 1991-06-11 | 1991-12-11 | $7700.00 | Window Closed / Lapsed |