Illumination – Supported by vehicle structure – Plural light sources
Reexamination Certificate
2002-08-06
2003-10-28
Tso, Laura K. (Department: 2875)
Illumination
Supported by vehicle structure
Plural light sources
C362S544000, C362S540000, C362S241000, C362S297000, C362S346000
Reexamination Certificate
active
06637923
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISK APPENDIX
Not applicable.
BACKGROUND OF THE INVENTION
The present invention relates to a vehicular lamp of a type employing an LED light source, and more particularly to such a vehicular lamp which is constructed so as to radiate light by indirect illumination.
Recently, vehicular lamps provided with an LED light source have frequently been employed. As described in Japanese Patent Application Laid-Open No. 11-306810, a lamp has been developed which provides a soft lighting effect using an indirect illumination technique whereby the LED light source is arranged so as not to be visible from the front of the lamp. To achieve this effect, the lamp employs a Fresnel lens together with the LED light source.
As shown in
FIG. 10
, such a lamp is structured such that light from an LED light source
102
, which is arranged facing upward, is formed into an upward directed parallel light flux by a Fresnel lens
104
provided near the upper side of the LED light source
102
, and the parallel light flux from the Fresnel lens
104
is then directed in a diffused manner toward the front of the lamp by a reflector
106
. The reflector
106
of the vehicular lamp is formed with a stepped shape whereby the reflecting surface
106
a
thereof is divided into a plurality of segments arranged at a uniform interval H′ with respect to the vertical direction (the direction of the optical axis Ax′ of the Fresnel lens
104
), and a reflective element
106
s
reflecting the parallel light flux in a diffused manner toward the front of the lamp and a step portion
106
r
extending in the vertical direction are provided in each of the segments.
In the conventional vehicular lamp described above, since the reflector
106
, which is formed generally as a flat plate, is inclined at a predetermined angle with respect to the direction of the optical axis Ax′, and the widths of the reflective elements
106
s
in the longitudinal direction of the lamp are all the same value w′ (the heights of the reflective elements
106
s
in the vertical direction are all the same width h′), problems as will now be described occur.
Since the light emitted by the LED light source
102
has a luminous intensity distribution I wherein the maximum luminous intensity occurs in the directly frontward direction and the luminous intensity is reduced as the angle with respect to the directly frontward direction increases, the light flux per unit area of the Fresnel lens
104
is high in an area near the optical axis Ax′ and becomes reduced in peripheral areas. Further, a solid angle per unit area of the Fresnel lens
104
with respect to the LED light source
102
is large in the area near the optical axis Ax and becomes small in the peripheral areas (&thgr;a′>&thgr;b′>&thgr;c′>&thgr;d′). Accordingly, the light flux per unit area striking the reflective elements
106
s
in peripheral areas on both of upper and lower sides of the central area near an intersection point C′ with respect to the optical axis Ax′ on the reflecting surface
106
a
is smaller (øa′>øb′>øc′>ød′) than that striking the reflective elements
106
s
constituting the central area.
Therefore, when viewing the reflecting surface
106
a
of the reflector
106
from the front of the lamp when the lamp is lit, while the reflective elements
106
s
in the central area are seen brightly, the reflective elements
106
s
constituting the peripheral areas appear dark, so that there is a problem that the overall appearance of the lamp is not as good as desired.
Taking the foregoing into consideration, it is an object of the present invention to provide a vehicular lamp of a type in which light from an LED light source is irradiated by indirect illumination whereby the lamp has an improved appearance when the lamp is lit.
BRIEF SUMMARY OF THE INVENTION
The present invention achieves the above and other objects by providing a lamp of the above-described type but in which the size of each of the reflective elements constituting the reflecting surface of the reflector is determined so as to obtain more uniform illumination.
More specifically, a vehicular lamp according to the present invention comprises an LED light source, a lens for forming light from the LED light source into a parallel light flux, a reflector for reflecting the parallel light flux toward the front of the lamp, and a translucent cover provided in front of the reflector of the lamp, wherein the reflecting surface of the reflector is sectioned into a plurality of segments at a substantially uniform interval with respect to the radiating direction of the parallel light flux, and a reflective element and a step portion are provided in each of the segments, whereby the reflecting surface is formed in a stepped shape, and the width in a longitudinal direction of the lamp of each of the reflective elements is determined such that, compared to a reflective element constituting a central area positioned near an intersection point with respect to a central axis of the parallel light flux on the reflecting surface, reflective elements is peripheral areas on both sides in the radiating direction of the parallel light flux with respect to the central area becomes wider.
The specific structure of the lens is not particularly limited as far as the lens can form the light from the LED light source into a parallel light flux, for example, it is possible to employ a single spherical lens, a combination lens, a Fresnel lens or the like.
The direction of the optical axis of the lens is not limited to a specific direction as far as the direction corresponds to a direction intersecting the longitudinal direction of the lamp, for example, it is possible to set the direction of the optical axis in an upward direction or a lateral direction by making the direction perpendicular to the longitudinal direction of the lamp.
The central axis of the parallel light flux is generally set to be coaxial with the optical axis of the lens; however, it may be set to a direction slightly inclined with respect to the optical axis of the lens. The latter setting can be achieved by arranging the LED light source at a position offset from the optical axis of the lens, providing light deflecting means near the reflector side of the lens, or the like.
As described above, the vehicular lamp according to the present invention is structured such that the reflecting surface of the reflector which reflects the light from the LED light source, made into the form of a parallel light flux by the Fresnel lens, toward the front of the lamp is sectioned into a plurality of segments substantially at a uniform interval with respect to the radiating direction of the parallel light flux. Moreover, a reflective element and a step portion are provided in each of the segments, whereby the reflecting surface is formed in the stepped shape. The width in the longitudinal direction of the lamp of each of the reflective elements is determined such that the reflective elements constituting the peripheral areas on both sides in the radiating direction of the parallel light flux with respect to the central area near the intersection point with the central axis of the parallel light flux on the reflecting surface are wider than the reflective elements constituting the central area. Due to this construction, the following effects are obtained.
That is, as described above, since the light flux per unit area of the parallel light flux reaching the reflecting surface of the reflector from the lens is smaller in the peripheral areas than in the central area of the reflecting surface in the conventional lamp, the reflective elements constituting the central area generally appear bright while the reflective elements constituting the peripheral areas appear more d
Koito Manufacturing Co. Ltd.
Tso Laura K.
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