Active solid-state devices (e.g. – transistors – solid-state diode – Thin active physical layer which is – Heterojunction
Reexamination Certificate
2002-08-30
2004-11-02
Chaudhari, Chandra (Department: 2813)
Active solid-state devices (e.g., transistors, solid-state diode
Thin active physical layer which is
Heterojunction
C257S088000, C257S089000
Reexamination Certificate
active
06812481
ABSTRACT:
The present application is based on Japanese Patent Applications No. 2001-265422, 2001-265423 and 2001-265424, which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a light-emitting diode lamp (hereinafter referred to as “LED lamp”) in which a single light-emitting element or a plurality of light-emitting elements, and leads and wires electrically connected to the single or plurality of light-emitting element(s) are packed in a package such as a synthetic resin package and sealed with a light-transmissive material such as a transparent epoxy resin. Incidentally, in this specification, an LED chip itself is called “light-emitting element” whereas a light-emitting device having a plurality of LED chips mounted therein is collectively called “light-emitting diode lamp” or “LED lamp”, further, more comprehensively called “LED device”. A lead frame as a raw material thereof is called “LED lead frame”.
2. Description of the Related Art
A surface mounting chip LED (SMD) type LED lamp has been heretofore used in a light source for a backlight unit, or the like. In the SMD type LED lamp, a plurality of metal leads disposed in an injection-molded synthetic resin package, and a plurality of light emitting elements mounted on one of the leads and electrically connected to the other leads by wire-bonding are entirely sealed with a transparent epoxy resin or the like.
In the LED lamp having such a plurality of light-emitting elements, however, luminous intensity distribution characteristic varies in accordance with the respective light-emitting elements. Moreover, heat-radiating characteristic is worsened compared with that of a package of a single light-emitting element. Hence, the respective light-emitting elements become uneven both in heat-radiating characteristic and in light-emitting efficiency. In addition, there arises a problem that color-mixing characteristic is worsened when a plurality of light-emitting elements different in wavelength are mounted in the LED lamp.
Further, in this LED lamp, however, lead portions (LED leads) by which the lamp is bonded on the mount board via solder is made flat. The viscosity of solder is reduced instantaneously when the LED lamp is made to pass through a reflow furnace at a high temperature in order to solder the LED lamp onto the mount board. For this reason, surface tension of solder is applied on the lead portions but the LED lamp is hardly positioned because the lead portions are so flat that the LED lamp slides. For this reason, in the LED lamp having such leads bent once, there is a problem that accurate mounting can be hardly made.
Still further, an example of a related-art LED lead frame for the LED lamp will be described with reference to FIG.
7
.
FIG. 7
is a plan view showing the configuration of the related art LED lead frame.
As shown in
FIG. 7
, in the LED lead frame
21
, four electrically conductive leads
25
a,
25
b,
25
c
and
25
d
are protruded inward from an outer frame
23
so that an injection-molded synthetic resin package
22
is fixed to tips of the leads. A plurality of light-emitting elements are mounted in the package
22
, electrically connected to the LED lead frame
21
by wire-bonding and then sealed with a sealing resin. Thus, a body portion of an LED lamp is produced. Then, the electrically conductive leads
25
a,
25
b,
25
c
and
25
d
are cut into a predetermined length and then bent along the outer circumference of the package
22
. Thus, a surface-mountable LED lamp is obtained.
In the LED lead frame
21
, however, nothing supports the package
22
after the electrically conductive leads
25
a,
. . . , and
25
d
are cut. Therefore, the package
22
must be fixed by a jig or something when the electrically conductive leads
25
a,
. . . , and
25
d
are to be bent back or forth along the outer circumference of the package
22
. For this reason, there is fear that the package
22
may be broken. Moreover, the electrically conductive leads
25
a,
. . . , and
25
d
cannot be bent accurately because the package
22
cannot be fixed firmly. Hence, there is a problem that inconsistency in positioning accuracy with respect to a partner member may occur in a post-process.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide an SMD type LED device in which uniformity of luminous intensity distribution characteristic in respective light-emitting elements and improvement both in heat radiating characteristic and in color-mixing characteristic can be achieved.
Another object of the present invention is to provide an LED device which can be positioned stably without sliding of the LED device when soldered onto a mount board and which can be mounted on the mount board accurately.
Still another object of the present invention is to provide a method for manufacturing an LED device lead frame in which electrically conductive leads can be bent with stable accuracy while a package is fixed firmly without being damaged in a process of bending the electrically conductive leads, and an LED device lead frame used for manufacturing the LED device.
(1) According to the invention, there is provided an LED device having: a plurality of light-emitting elements sealed with a light-transmissive material in a package, wherein: the plurality of light-emitting elements are arranged in a single row in the inside of an opening portion of the package and in order of element height so that a light-emitting element higher in element height is disposed on an outer side of the single row; and the inside of the opening portion of the package is sealed with the light-transmissive material.
The light-transmissive material for sealing the inside of the opening portion of the package is shrunk when cured from a liquid state. For this reason, the surface of the light-transmissive material in the center portion of the package is dented so that the outer side of the package becomes higher than the center portion. Accordingly, when the plurality of light-emitting elements are arranged in such order of element height that a light-emitting element higher in element height is disposed on an outer side of the single row, distances from light emitting surfaces of the respective light-emitting elements to the surface of the light-transmissive material are made uniform, so that luminous intensity distribution characteristic is made uniform.
In this manner, in the LED device having a plurality of light-emitting elements sealed with a light-transmissive material in a package, luminous intensity distribution characteristic can be improved.
(2) According to the invention, in the LED device having the configuration defined in (1), one sheet of electrically conductive lead for mounting the plurality of light-emitting elements protrudes out of the package to thereby form a protrusion provided in a center portion of the package.
With such a configuration, distances from the respective light-emitting elements to a heat-radiating portion are made uniform, so that heat radiation is made uniform. Accordingly, light-emitting efficiency is made uniform, so that the LED device can be provided as an excellent LED device.
(3) According to the invention, in the LED device having the configuration defined in (1) or (2), the opening portion has its periphery constituted by slopes provided in a lengthwise direction of the package and slopes provided in a widthwise direction of the package, and the slopes provided in the lengthwise direction are different in inclination from the slopes provided in the widthwise direction so that the inclination of the slopes provided in the widthwise direction is gentler.
With such a configuration, the opening portion is formed so that light is not diffused in the lengthwise direction but light is diffused in the widthwise direction. Hence, it is easy to guide light into a thin light guide plate. This contributes to increase in luminance of a backlight unit. In addition, when a plurality of such LED devices are used, color mixing c
Kato Hideaki
Matsumura Kanae
Ohtsuka Shunsuke
Takahashi Yuji
Blum David S.
Chaudhari Chandra
McGinn & Gibb PLLC
Toyoda Gosei Co,., Ltd.
LandOfFree
LED device and manufacturing method thereof does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with LED device and manufacturing method thereof, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and LED device and manufacturing method thereof will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3314074