Illumination – Light modifier – Refractor
Reexamination Certificate
2000-06-27
2001-07-10
Tso, Laura K. (Department: 2875)
Illumination
Light modifier
Refractor
C362S309000, C362S800000
Reexamination Certificate
active
06257742
ABSTRACT:
The present invention is for a lighting means having light emitting diodes. The means is primarily intended to be used in light signal devices, e.g. traffic light means.
Traffic light means and other signal lamps of similar kinds have hereto had known incandescent filament lamps having a lens positioned in front of the lamp in order to achieve a light pattern according to certain requirements. Incandescent filament lamps have in some lighting means been replaced by light emitting diodes which are mounted in parallel, preferably horizontal, rows. Also this kind of lighting means have a lens to give a light pattern and to equalise the luminance over the surface and reduce the impression of lighting spots or dots. The design of the lens s adapted to the rows of light emitting diodes and the surface of the lens is correspondingly divided into parallel rows or bands. This kind of lenses are known from e.g. U.S. Pat. No. 5,032,963 disclosing a means intended to be used with a single light source which via a reflector emits a parallel beam of rays. The lens is divided into a large number of smaller partial lenses which are arranged in horizontal rows. WO-97/26483 discloses a device for light emitting diodes with a lens where the horizontal bands are divided into several smaller partial bands. At least one of these is in its turn divided into smaller parts which are<arranged at the side of each other having vertical dividing lines or surfaces. These designs are comparatively complicated and bring with them high costs of manufacturing.
One object of the present invention is a lighting means of the above mentioned art having light emitting diodes which are arranged in rows and a lens to give the desired light pattern. Another object of the invention is to eliminate or reduce the impression of separate light spots or dots so that the lighted surface is seen as evened. It is a further object of the invention t achieve the desired light pattern by a simpler lens design without partition of the horizontal bands of the lens in vertically separated parts whereby cost advantages are achieved. It is also an object of the invention to achieve adaptation to light emitting diodes of different luminance.
According to the invention the above mentioned objects are achieved by a linear lens structure comprising a lens which is divided into bands, each band having several curved, nonsphere surfaces. When looked upon each light emitting diodes causes several light spots thereby that each light emitting diode is seen at several positions. If the lighting means is looked at straight or almost straight from the front three or four light spots are seen, from other directions at least two light spots. The impression will be that of a surface which is better enlighted than in the case where one light emitting diode gives only one light spot. The lighting means of the invention has those characteristics which are mentioned in claim
1
. Further characteristics of embodiments of the invention are given in the other claims.
REFERENCES:
patent: 4467193 (1984-08-01), Carrell
patent: 5032963 (1991-07-01), Granström
patent: 5174649 (1992-12-01), Alston
patent: 5515253 (1996-05-01), Sjobom
patent: 5765940 (1998-06-01), Levy et al.
patent: 5806969 (1998-09-01), Rosengren
patent: 5833355 (1998-11-01), You et al.
patent: WO 97/26483 (1997-07-01), None
Itab Neon AB
Pillsbury & Winthrop LLP
Tso Laura K.
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