Patent US5031035A successfully refreshed from Google Patents.
EP0442529A2
Expired / Lapsed
EP
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Back lighting device for a panel
Assignee: Toshiba Corp
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Filing: 1991-02-15
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Granted: —
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Expires: 2011-02-15
Abstract
Abstract An improved backlighting device for liquid-crystal display panels comprising a linear light source (4) the length of which is equal to or less than the length of an end portion of a light conducting plate (1) at which light is admitted from the linear light source (4) placed adjacent to it, the linear light source being enclosed with a light diffusing reflector (5) that has a slit formed in the surface through which incident light is admitted into the light conducting plate (1) and which is provided in such a way as to form a clearance from the surface of the linear light source (4), one major surface of the light conducting plate (1) being partially covered with a light diffusing material under specified conditions that has a higher refractive index than the material of which the light conducting plate (1) is made, the major surface being further covered with a specular or light diffusing/reflecting plate (3), with a plurality of light diffusing plates (2) being provided on the other major (light emerging) surface of the light conducting plate (1).
Inventors
- 👤 Keiji Kashima
- 👤 Naoki Yoshida
- 👤 Osamu Shoji
- 👤 Eiichi Yanagi
- 👤 Takumi Fukunishi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 01:43
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/0001; G02B6/0011; G02B6/0033; G02B6/005; G02B6/0051
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
418 words
A back lighting device for a liquid-crystal panel which comprises: a light conducting plate made of a light-transmissive material; a linear light source provided at the end portion of at least one side of said light conducting plate, at least the portion of said linear light source which is capable of uniform light emission being equal to or less than the length of said end portion, said linear light source being enclosed with a light diffusing reflector that has a slit through which light emitted from said linear light source is admitted into one side of the light conducting plate and that is provided in such a way a clearance is left between the outer surface of the linear light source and the opposing inner surface of said reflector; a coating of a light diffusing material that has a higher refractive index than said light-transmissive material and that is provided in a dot pattern on one major surface of said light conducting plate in such a way as to provide an area in which the coverage (Y) of said coating satisfies the functional relationship Y = aX n or Y = a x or the approximate relationship thereof where x or x represents the distance from the linear light source; n = 1.7 - 3.5; and a is a constant determined by regression of a mathematical expression) and in such a way that the coverage (Y') of said coating which is provided on said major surface of the light conducting plate in an increasing amount towards both ends of a line parallel to the axis of said inear light source satisfies the functional relationship Y' = a'X' n or Y' = a' X' or the approximate relationship thereof (where X' or x' represents the distance the coating departs from a line vertical to the center of the linear light source towards both ends thereof; n = 1.7 - 3.5; and a' is a constant determined by regression of a mathematical expression) over the range from the area that is the nearest to the linear light source and where X' is at maximum (each end of the light conducting plate) to the area where Y = Y' with Y' decreasing or increasing gradually, and/or is constant with increasing X along said both ends of the light conducting plate; a specular or light diffusing/replacing plate that covers said coated surface; and at least one light scattering plate provided on the other major (light emerging) surface of said light conducting plate.
Claim 2
Dependent Claim
37 words
A back lightening device for a liquid-crystal panel according to claim 1 further comprising: a specular reflecting member that covers the end face of said light conducting plate which is the farthest from said linear light source.
Claim 3
Dependent Claim
121 words
A back lightening device for a liquid-crystal panel comprising: a light conducting plate made of a light-transmissive material; a linear light source provided in close proximity to the end portion of at least one side of said light conducting plate; a coating of a light diffusing material that has a higher refractive index than said light-transmissive material and that is provided on one surface of said light conducting plate in such a way that the coverage of said coating increases with the distance from the linear light source; a specular reflecting plate or a light diffusing/reflecting plate that covers said one surface; and a plurality of light scattering plates provided on the other (light emerging) surface of said light conducting plate.
Claim 4
Dependent Claim
37 words
A back lightening device for a liquid-crystal panel according to claim 3 further comprising: a specular reflecting member that covers the end face of said light conducting plate which is the farthest from said linear light source.
Claim 5
Dependent Claim
56 words
A back lighting device for a liquid-crystal panel according to claim 3, in which the coverage of the light conducting plate with said light diffusing material increases in proportion to a power of the distance from the linear light source, said power being in the range of 1.7 - 3.5 or with the approximate relationship thereof.
Claim 6
Dependent Claim
106 words
A back lighting device for a liquid-crystal panel according to claim 3, in which at least the portion of said linear light source which is capable of uniform light emission is equal to or less than the length of said end portion, and said linear light source is enclosed with a light diffusing reflector that has a slit through which light emitted from said linear light source is admitted into one side of the light conducting plate and that is provided in such a way a clearance is left between the outer surface of the linear light source and the opposing inner surface of said reflector.
Claim 7
Dependent Claim
259 words
A back lighting device for a liquid-crystal panel according to claim 6, in which said coating of a light diffusing material is provided in a dot pattern on said one surface of said light conducting plate in such a way as to provide an area in which the coverage (Y) of said coating satisfies the functional relationship Y = aX n or Y = a x or the approximate relationship thereof (where X or x represents the distance from the linear light source; n = 1.7 - 3.5; and a is a constant determined by regression of a mathematical expression) and in such a way that the coverage (Y') of said coating which is provided on said surface of the light conducting plate in an increasing amount towards both ends of a line parallel to the axis of said linear light source satisfies the functional relationship Y' = a'X' n or Y' = a' x' or the approximate relationship thereof (where X' or x' represents the distance the coating departs from a line vertical to the center of the linear light source towards both ends thereof; n = 1.7 - 3.5; and a' is a constant determined by regression of a mathematical expression) over the range from the area that is the nearest to the linear light source and where X' is at maximum (each end of the light conducting plate) to the area where Y = Y' with Y' decreasing or increasing gradually and/or is constant with increasing X along said both ends of the light conducting plate.
Claim 8
Dependent Claim
128 words
A back lighting device for a liquid-crystal panel which comprises: a light conducting plate made of a light-transmissive material; a linear light source provided in close proximity to the end portion of one side of said light conducting plate; a first coating of a light diffusing material that has a higher refractive index than said light-transmissive material and that is provided on one major surface of said light conducting plate in such a way that the coverage of said first coating increases with the distance from the end portion of said one side of said light conducting plate which faces said linear light source; and a specular reflecting member that covers the end face of said light conducting plate which is the farthest from said linear light source.
Claim 9
Dependent Claim
125 words
A back lighting device for a liquid-crystal panel according to claim 8 further comprises: a second coating of a light diffusing material that has a higher refractive index than said light-transmissive material and that is provided on one major surface of said light conducting plate in such a way that the neighborhood of the end portion of said light conducting plate which is the farthest from said linear light source has an area in which the coverage of said second coating is equal to that in the other areas or an area in which the coverage of said coating is greater than that in the other areas but in which the rate of increase of said coverage is smaller than that in the other areas.
Claim 10
Dependent Claim
45 words
A back lightening device for a liquid-crystal panel according to claim 8 further comprising: a specular or light diffusing/replacing plate that covers said coated surface; and at least one light scattering plate provided on the other major (light emerging) surface of said light conducting plate.
Claim 11
Dependent Claim
54 words
A back lighting device for a liquid-crystal panel according to claim 8, in which the coverage of said first coating of the light conducting plate with said light diffusing material increases in proportion to a power of the distance from the linear light source, said power being in the range of 1.7 - 3.5.
Claim 12
Dependent Claim
106 words
A back lighting device for a liquid-crystal panel according to claim 8, in which at least the portion of said linear light source which is capable of uniform light emission is equal to or less than the length of said end portion, and said linear light source is enclosed with a light diffusing reflector that has a slit through which light emitted from said linear light source is admitted into one side of the light conducting plate and that is provided in such a way a clearance is left between the outer surface of the linear light source and the opposing inner surface of said reflector.
Claim 13
Dependent Claim
99 words
A back lighting device for a liquid-crystal panel according to claim 12, in which said coating of a light diffusing material is provided in a dot pattern on said one surface of said light conducting plate in such a way as to provide an area in which the coverage (Y) of said coating satisfies the functional relationship Y = aX n or Y = a x or the approximate relationship (where X or x represents the distance from the linear light source; n = 1.7 - 3.5; and a is a constant determined by regression of a mathematical expression).
References Cited (Backward Citations)
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