Patent US3752974A successfully refreshed from Google Patents.
US3752974A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Uniform illumination with edge lighting
Assignee: COASTAL DYNAMICS INCORPORATED A CORP OF OREG
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Filing: 1971-12-13
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Granted: 1973-08-14
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Expires: 1991-12-13
Abstract
Abstract Uniform illumination is provided from an edge lighted optical medium of a given thickness by diffusing a surface portion normally providing internal reflection of the light radiated into the edge such that at least some of the light rays striking the diffused area are reflected through the opposite surface of the medium and some are refracted through the one surface. A cleared area about the source of light free of the diffusion is provided and treated by application of coatings on opposite surface portions of the medium defining the cleared area. These coatings have an index of refraction less than that of the medium such that light is channeled by internal reflection between the surfaces of the medium and inhibited from escaping from the medium in the vicinity of the cleared area. This cleared area has a radius of preferably three to four times the thickness of the optical medium. The resulting light emmination from the surface of the medium is substantially uniform beyond the cleared area.
Inventors
- 👤 M Baker
- 👤 L Myers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 23:44
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/0001; G02B6/0011; G02B6/0013; G02B6/0015; G02B6/002; G02B6/0021; B; B60; B60Q; B60Q3/00; B60Q3/10; B60Q3/14; B60Q3/60; B60Q3/62; B60Q3/64; G02B6/0033; G02B6/005; G02B6/0055; B60K; B60K2360/00; B60K2360/20; B60K2360/33; B60K2360/336; G02B6/0035; G02B6/0036
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
197 words
A method of providing substantially uniform illumination from an edge lighted optical medium of thickness T, comprising the steps of: a. diffusing one surface portion normally providing internal reflection of the light such that at least some of the light rays striking the diffused surface are reflected through the opposite surface and some are refracted through the one surface to escape out of the medium; b. providing a cleared area about the source of light free of the diffusion; and, c. treating the cleared area by providing an interface for the surfaces of the optical medium defining the cleared area, said interface having an index of refraction less than that of the medium to assure internal reflection of light rays in the cleared area such that light is channeled by internal reflection between the surfaces and inhibited from escaping from the medium in the vicinity of the cleared area, the channeled light rays expanding towards the diffused surface portion so that the light escaping from the medium as a consequence of the diffused surface portion is substantially uniform with increasing distance from the lighted edge as measured in a plane parallel to the plane of the medium.
Claim 2
Independent Claim
197 words
A method of providing substantially uniform illumination from an edge lighted optical medium of thickness T, comprising the steps of: a. diffusing one surface portion normally providing internal reflection of the light such that at least some of the light rays striking the diffused surface are reflected through the opposite surface and some are refracted through the one surface to escape out of the medium; b. providing a cleared area about the source of light free of the diffusion; and, c. treating the cleared area by providing an interface for the surfaces of the optical medium defining the cleared area, said interface having an index of refraction less than that of the medium to assure internal reflection of light rays in the cleared area such that light is channeled by internal reflection between the surfaces and inhibited from escaping from the medium in the vicinity of the cleared area, the channeled light rays expanding towards the diffused surface portion so that the light escaping from the medium as a consequence of the diffused surface portion is substantially uniform with increasing distance from the lighted edge as measured in a plane parallel to the plane of the medium.
Claim 3
Dependent Claim
49 words
The method of claim 1 including the step of providing a highly specular surface under the diffused portion of the optical medium to reflect light refracted through the one surface back into the medium so that the level of the uniform illumination from the opposite surface is substantially increased.
Claim 4
Dependent Claim
36 words
The method of claim 2 including the additional step of providing a highly specular surface about the edges of the optical medium except the edge portion admitting light to block light from escaping from the edges.
Claim 5
Dependent Claim
45 words
The method of claim 1, in which said cleared area has a circular end boundary defined at least in part by a circle with the source of light at the center of the circle, said circle having a radius which lies between T and 10T.
Claim 6
Dependent Claim
22 words
The method of claim 4, in which said radius is from three to four times the thickness T of the optical medium.
Claim 7
Dependent Claim
29 words
The method of claim 1, in which said interface is in the form of a coating of material having an index of refraction less than that of the medium.
Claim 8
Dependent Claim
175 words
A means for providing substantially uniform illumination over a large surface area comprising: a. an optical medium having opposite surfaces defining a first surface and a second surface parallel to each other and separated by a distance T defining the thickness of said medium; and, b. at least one light source at an edge of said medium for radiating light into the edge of the medium between said surfaces; c. said first surface having a diffused surface portion over a large surface area for reflecting and refracting internally reflected light radiated between said surfaces from said source out of said medium; d. said first surface having a cleared area about said source free of diffusion, the periphery of said cleared area being at a distance from said source greater than T and less than 10T; and, e. a coating of material having an index of refraction less than that of said medium on the surface portions of said medium defining said cleared area to thereby assure internal reflection of light rays in said cleared area.
Claim 9
Dependent Claim
175 words
A means for providing substantially uniform illumination over a large surface area comprising: a. an optical medium having opposite surfaces defining a first surface and a second surface parallel to each other and separated by a distance T defining the thickness of said medium; and, b. at least one light source at an edge of said medium for radiating light into the edge of the medium between said surfaces; c. said first surface having a diffused surface portion over a large surface area for reflecting and refracting internally reflected light radiated between said surfaces from said source out of said medium; d. said first surface having a cleared area about said source free of diffusion, the periphery of said cleared area being at a distance from said source greater than T and less than 10T; and, e. a coating of material having an index of refraction less than that of said medium on the surface portions of said medium defining said cleared area to thereby assure internal reflection of light rays in said cleared area.
Claim 10
Dependent Claim
45 words
The subject matter of claim 7, in which said diffused surface portion includes total reflecting means for reflecting back into said medium any refracted light otherwise escaping out of said medium through said first surface so that light is directed out of said second surface.
Claim 11
Dependent Claim
29 words
The subject matter of claim 7, including total reflecting means about the edges of said medium except for the edge portion into which light is radiated from said source.
Claim 12
Dependent Claim
59 words
The subject matter of claim 7, in which said cleared aRea has a circular end boundary defined at least in part by a circle with the light source at the center of the circle, the radius of the circle lying between 3T and 4T and in which said optical medium has a refractive index of between 1.42 and 2.00.
Claim 13
Dependent Claim
205 words
The subject matter of claim 7, in which said medium comprises an acrylic panel, said coating of material being co-extensive with said cleared area on said first surface, said material being transparent and covering the entire second surface of said acrylic panel; a coating of acrylic overlying said coating of material on said entire second surface; a coating of translucent white vinyl overlying said coating of acrylic on said second surface; and a coating of opaque vinyl overlying said coating of white vinyl, portions of said opaque vinyl being removed on said second surface to define nomenclature, the said first surface having a coating of acrylic overlying said coating of material on said cleared area and extending beyond said cleared area a first given distance; a coating of opaque vinyl overlying a portion of said coating of acrylic on said cleared area and terminating short of said cleared area by a second given distance, said diffused surface being provided by a coating of white vinyl on said first surface outside said cleared area; and a coating of opaque vinyl overlying the entire first surface whereby an edge lighted panel is provided in which light emitted through the openings defined by said nomenclature is substantially uniform.
Claim 14
Dependent Claim
63 words
The subject matter of claim 11, in which said cleared surface has a circular end boundary defined at least in part by a circle with said light source at the center of the circle, the circle having a radius R between 3T and 4T said first given distance being from 0.25R to 0.75R and said second given distance being from 0.1R to 0.5R.
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) | 1976-08-13 | 1977-02-12 | 1977-08-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-13 | 1981-02-12 | 1981-08-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-13 | 1985-02-12 | 1985-08-14 | $7700.00 | Window Closed / Lapsed |