Illumination – Light source and modifier – Including reflector
Reexamination Certificate
2002-04-09
2003-11-04
O'Shea, Sandra (Department: 2875)
Illumination
Light source and modifier
Including reflector
C362S346000, C362S350000, C362S800000, C257S094000, C257S098000, C313S512000
Reexamination Certificate
active
06641287
ABSTRACT:
The present application is based on Japanese Patent Application No. 2001-112456, which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a reflective type light-emitting diode (hereinafter abbreviated as “reflective type LED”) having a light source having a light-emitting element mounted on a lead forming a reflecting mirror, and a reflecting mirror provided in opposition to the light source. Incidentally, in this specification, an LED chip itself is referred to as “light-emitting element”, an emitter including a resin package or an optical device such as a lens system having an LED chip mounted thereon is referred to as “light source”, and a light-emitting device having a light source mounted thereon is generically referred to as “light-emitting diode” or “LED”.
2. Description of the Related Art
An example of a related-art reflective type LED will be described below with reference to FIG.
4
.
FIG. 4
is a vertically sectional view showing the overall configuration of the related-art reflective type LED. As shown in
FIG. 4
, in the reflective type LED
30
, a pair of leads
33
a
and
33
b
are provided for supplying electric power to a GaAs light-emitting element
32
which is mounted on one
33
a
of the leads
33
a
and
33
b
. The light-emitting element
32
and the other lead
33
b
are bonded to each other by a wire
34
. A reflecting mirror
35
made from an aluminum sheet excellent in linear reflectance and pressed into a concave shape is disposed in opposition to a light-emitting surface of the light-emitting element
32
. The light-emitting element
32
, part of the pair of leads
33
a
and
33
b
, the wire
34
and the reflecting mirror
35
are sealed with a transparent epoxy resin
36
. A light-radiating surface
36
a
is formed on a back surface side of the light-emitting element
32
.
The reflecting mirror
35
has a reflecting surface formed as a paraboloid of revolution with the light-emitting element
32
as a focal point. Accordingly, all components of light emitted from the light-emitting element
32
and reflected by the reflecting mirror
35
are reflected in a direction parallel to the axis of the paraboloid of revolution and radiated from the light-radiating surface
36
a
to the outside. In such a manner, the reflective type LED
30
is configured with high external radiating efficiency.
In the reflective type LED
30
, however, the reflecting mirror
35
needs to have a solid angle of about 2&pgr; steradian to the light-emitting element to keep the external radiating efficiency high. That is, the reflecting mirror
35
must be formed to have an end portion reaching the height of the light-emitting surface of the light-emitting element
32
in order to reflect light radiated substantially horizontally from the light-emitting surface of the light-emitting element
32
. Therefore, the reflecting mirror
35
has to be disposed closely to the light-emitting element
32
. There arises a problem that the degree of freedom for designing the reflecting mirror
35
is restricted.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a reflective type light-emitting diode in which high external radiating efficiency can be obtained to increase the degree of freedom for designing a reflection mirror even in the case where an end portion of a reflecting mirror does not reach the height of a light-emitting surface of a light-emitting element.
(1) According to the invention, there is provided a reflective type light-emitting diode having: a light source including a light-emitting element, leads for supplying electric power to the light-emitting element, and a concave reflecting mirror provided around the light-emitting element; and a reflecting mirror provided in opposition to the light source.
In the reflective type LED configured as described above, the concave reflecting mirror is provided around the light-emitting element of the light source. Hence, light emitted from a light-emitting surface of the light-emitting element is not diffused horizontally but concentrated on a region within a predetermined extent from an axis perpendicular to the light-emitting surface. For this reason, all the reflecting mirror provided in opposition to the light source has to do is to reflect light irradiating the region within the predetermined extent from the axis perpendicular to the light-emitting surface. Hence, the end portion of the reflecting mirror need not reach the height of the light-emitting surface, so that the degree of freedom for designing the reflecting mirror can be increased while the reflecting mirror can be disposed to be far from the light source. Moreover, all components of light radiated from the light source can be substantially reflected by the reflecting mirror so as to be radiated to the outside with high external radiating efficiency.
In such a manner, there is provided a reflective type LED in which high external radiating efficiency can be obtained to increase the degree of freedom for designing the reflecting mirror even in the case where the end portion of the reflecting mirror does not reach the height of the light-emitting surface of the light-emitting element.
(2) According to the invention, there is provided a reflective type light-emitting diode of the configuration as defined in (1), wherein the reflecting mirror provided in opposition to the light source has a solid angle of not higher than 1.65&pgr; steradian to the light source.
As described above, the concave reflecting mirror is provided around the light-emitting element of the light source. Hence, light emitted from the light-emitting surface of the light-emitting element is not diffused horizontally but concentrated on a region within an extent of about 80 degrees from an axis perpendicular to the light-emitting surface. For this reason, all the reflecting mirror provided in opposition to the light source has to do is to reflect light irradiating the region within the extent of about 80 degrees from the axis perpendicular the light-emitting surface. This extent of about 80 degrees corresponds to a solid angle of about 1.65&pgr; steradian. Hence, the reflecting mirror may have a solid angle of not higher than 1.65&pgr; steradian. Accordingly, the end portion of the reflecting mirror need not reach the height of the light emitting surface, so that the degree of freedom for designing the reflecting mirror can be increased while the reflecting mirror can be disposed to be far from the light source. Moreover, all components of light radiated from the light source can be substantially reflected by the reflecting mirror so as to be radiated to the outside with high external radiating efficiency.
In such a manner, there is provided a reflective type LED in which high external radiating efficiency can be obtained to increase the degree of freedom fort designing the reflecting mirror even in the case where the end portion of the reflecting mirror does not reach the height of the light-emitting surface of the light-emitting element.
(3) According to the invention, there is provided a reflective type light-emitting diode of the configuration as defined in (1) or (2), wherein the light source further includes a light-transmissive material for sealing the light-emitting element, part of the leads and the concave reflecting mirror and for forming a light-radiating surface on the light-emitting surface side of the light-emitting element.
In the reflective type LED configured as described above, the light-emitting element is sealed with the light-transmissive material, so that the light quantity emitted from the light-emitting element becomes about twice as large as that in the case where the light-emitting element is not sealed. As a result, the luminous intensity of the light source and, accordingly, the luminous intensity of the reflective type LED increase greatly. In addition, the light-radiating surface is formed on the light-emitting surface side of the light-emitting element, so that li
Cranson, Jr. James W
McGinn & Gibb PLLC
O'Shea Sandra
Toyoda Gosei Co,., Ltd.
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