Internally illuminated sign
First Claim
1. An internally illuminated sign, comprising:
- at least one source of light; and
at least one display surface illuminated by said light and comprising regions generally opaque to said light and regions diffusively transmissive to said light, said diffusively transmissive regions forming at least one character to be displayed by said sign, wherein said at least one source of light is mounted such that said light is directed at said at least one display surface at close to a glancing angle, and said at least one display surface has a curved contour, concave to said at least one source, and such that light from said at least one source impinges on said display surface at an angle of incidence which varies according to the distance of the point of impingement of said light from said light source.
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Accused Products
Abstract
An illuminated sign, internally illuminated by a source such as one or more LED'"'"'S generally located at one end, and having a character panel with at least partially transmissive portions to define the characters of the sign. The character panel is curved so as to face the source more squarely at distances further from the source. By this arrangement, the geometric fall-off of illumination with increasing distance from the source is compensated for by the curvature of the character panel, such that more uniform illumination is provided than with prior art flat panels. Power management systems for solar charged illuminated signs are also described, in which the illumination level of the sign is adjusted according to the ambient solar flux and according to the charge-holding capacity of the battery. The system also warns of the impending end of battery life without interrupting the sign functionality.
68 Citations
20 Claims
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1. An internally illuminated sign, comprising:
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at least one source of light; and
at least one display surface illuminated by said light and comprising regions generally opaque to said light and regions diffusively transmissive to said light, said diffusively transmissive regions forming at least one character to be displayed by said sign, wherein said at least one source of light is mounted such that said light is directed at said at least one display surface at close to a glancing angle, and said at least one display surface has a curved contour, concave to said at least one source, and such that light from said at least one source impinges on said display surface at an angle of incidence which varies according to the distance of the point of impingement of said light from said light source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of improving the uniformity of illumination on at least one display surface of an internally illuminated sign, comprising the steps of:
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providing at least one source of light for illuminating said at least one display surface;
providing said display surface with a curved contour; and
directing said light at said display surface at close to a glancing angle, such that said curved contour reduces variations in the luminous flux per unit area of said light impinging on said at least one display surface, in comparison with variations in said luminous flux per unit area impinging on a corresponding non-curved display surface. - View Dependent Claims (15, 16)
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17. An electronic system for a solar charged, battery operated, illuminated sign, comprising:
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a solar panel providing an output in accordance with the solar illumination incident thereon;
at least one light source for illuminating said sign;
at least one battery chargeable by said output, for supplying current to said at least one light source, said at least one battery providing a voltage dependent on the state of said charge of said at least one battery; and
a controller programmed to control said current at least in accordance with said voltage, such that said current is reduced when said voltage falls below a first predetermined level. - View Dependent Claims (18, 19, 20)
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Specification