Active solid-state devices (e.g. – transistors – solid-state diode – Incoherent light emitter structure – With reflector – opaque mask – or optical element integral...
Reexamination Certificate
1999-12-15
2002-03-12
Mintel, William (Department: 2811)
Active solid-state devices (e.g., transistors, solid-state diode
Incoherent light emitter structure
With reflector, opaque mask, or optical element integral...
C257S099000, C257S100000
Reexamination Certificate
active
06355946
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a semiconductor device capable of emitting light and provided with a reflector for the light. More particularly, it relates to a semiconductor device, such as a light-emitting diode, used for backlighting a push button in a small electric device such as a portable telephone.
2. Description of the Related Art
Small electronic devices such as portable telephones have been widely used lately because of their handiness. Needless to say, portable telephones are provided with a number of push buttons operated for making a call or performing other functions. The push buttons of a recent portable telephone may be backlit by small light sources, so that the user can operate the device even in the dark. For the light source, use may be made of an LED (light-emitting diode).
FIGS. 12 and 13
show a conventional light-emitting diode provided with a reflector. As illustrated, the conventional diode Y is constituted by a rectangular base unit
1
′, an LED chip
3
′ mounted on the unit
1
′ and a casing
5
′ enclosing the LED chip
3
′.
The base unit
1
′ is composed of an insulating substrate
1
A′, a first electrode
2
A′ and a second electrode
2
B′. The electrodes
2
A′ and
2
B′, which are electrically insulated from each other, extend from the upper surface
10
′ of the substrate
1
A′ onto the lower surface
12
′ through a side surface
11
′. The electrodes
2
A′ and
2
B′ have upper portions
2
a
′ and
2
b
′, respectively, which extend on the upper surface
10
′ of the substrate
1
A′. These electrodes
2
A′,
2
B′ may be made by etching a conductive metal layer formed on the substrate
1
A′.
The LED chip
3
′ is arranged on the upper portion
2
a
′ of the first electrode
2
A′ and is electrically connected thereto. The top surface
30
′ of the LED chip
3
′ is electrically connected to the upper portion
2
b
′ of the second electrode
2
B′ via a wire
4
′ made of gold for example.
The casing
5
′ is formed with a cavity
50
a
′, defined by an inner wall surface
5
a
′ of the casing
5
′. As shown in
FIGS. 12 and 13
, the cavity
50
a
′ is made in the form of a reversed, truncated cone extending through the thickness of the casing
5
′. Thus, when the casing
5
′ is mounted on the substrate
1
A′, the LED chip
3
A′ and the wire
4
′ are disposed in the cavity
50
a′.
As shown in
FIG. 13
, the inner wall surface
5
a
′ is covered with a metal film
5
b
′ formed by sputtering or vacuum evaporation. The metal film
5
b
′ is rendered reflective so as to work as a light-reflecting member or reflector. As illustrated, the cavity
50
a
′ is filled up with transparent resin
50
′ (such as epoxy resin) which is highly permeable to light. The resin
50
′ will be referred to as the “light-permeable portion” below.
With the above arrangement, part of the light emitted from the LED chip
3
A′ is reflected by the metal layer
5
b
′ before getting out of the light-permeable member
50
′, while the other part of the emitted light passes through the light-permeable member
50
′ without being reflected by the metal layer
5
b
′. As a result, a light beam having a generally cylindrical form is emitted from the light-permeable member
50
′.
As stated above, the light-emitting diode Y, which is usable as a backlight for a push button of a portable telephone, is arranged to emit a generally cylindrical light beam. On the other hand, the push buttons of a portable telephone are often made in a non-circular form (e.g. elliptical or rectangular). Under these circumstances, the light-emitting diode Y fails to properly brighten the entirety of a push button. This shortcoming may be overcome by using more than one light-emitting diode Y for illuminating a single push button. However, it is clear that such a solution will disadvantageously lead to a cost increase.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a semiconductor device which is capable of properly backlighting a non-circular push button of an electronic device.
According to the present invention, there is provided a semiconductor device comprising:
a substrate provided with a first electrode and a second electrode formed thereon;
a semiconductor chip mounted on the substrate for emitting light, the semiconductor chip being electrically connected to the first electrode and the second electrode; and
a reflector enclosing the semiconductor chip for reflecting the light emitted from the semiconductor chip;
wherein the reflector has an elongated transverse section.
The elongated transverse section may be oblong, elliptical, rhombic, or rectangular.
According to a preferred embodiment of the present invention, the reflector may have a first vertical section defining a quadric curve.
Further, the reflector may have a second vertical section intersecting the first vertical section at right angles. The second vertical section may define a quadric curve.
The reflector may define a quadric surface tapering toward the semiconductor chip.
According to a preferred embodiment of the present invention, the semiconductor chip may be a light-emitting diode chip.
According to another preferred embodiment, the semiconductor chip may be a laser diode chip.
The semiconductor device of the present invention may further comprise a casing supported by the substrate. The casing may be provided with an inner surface defining a cavity, wherein the inner surface serves as the reflector.
Preferably, the casing may be made of a reflective material.
Preferably, the casing may be white.
Preferably, the casing may be made of a polycarbonate resin containing titanium oxide.
According to another preferred embodiment of the present invention, the semiconductor device may further comprise a casing supported by the substrate and a light reflecting film as the reflector. In this case, the casing may be provided with an inner surface defining a cavity, and the light reflecting film is formed on the inner surface.
Preferably, the light reflecting film may be made of metal.
Further, the light reflecting film may be white.
Preferably, the light reflecting film may be made of a polycarbonate resin containing titanium oxide.
The semiconductor device of the present invention may further comprise a light-permeable member, wherein the reflector defines a space accommodating the light-permeable member.
Preferably, the light-permeable member may be made of an epoxy resin.
Other features and advantages of the present invention will become apparent from the detailed description given below with reference to the accompanying drawings.
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patent: 3991339 (1976-11-01), Lockwood et al.
patent: 4013916 (1977-03-01), Brown
patent: 4152624 (1979-05-01), Knaebel
patent: 4964025 (1990-10-01), Smith
patent: 5291038 (1994-03-01), Hanamoto et al.
patent: 5479426 (1995-12-01), Nakanishi et al.
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patent: 8-204239 (1996-08-01), None
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patent: 97/12386 (1997-04-01), None
Michelitsch, “Light-Emitting, Gallium Arsenide Diode”, IBM Technical Disclosure Bulletin, vol. 8, No. 1, Jun. 1965, p. 191.*
International Search Report, Jun. 18, 2001.
Mintel William
Rohm & Co., Ltd.
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