Active solid-state devices (e.g. – transistors – solid-state diode – Incoherent light emitter structure – In combination with or also constituting light responsive...
Reexamination Certificate
2001-10-25
2002-09-03
Chaudhuri, Olik (Department: 2813)
Active solid-state devices (e.g., transistors, solid-state diode
Incoherent light emitter structure
In combination with or also constituting light responsive...
C257S100000
Reexamination Certificate
active
06445008
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a photo sensing device and the manufacturing method thereof, especially to a photo sensing device using surface-emitting LED as light source to increase responsive of photo receiver and prevent the short circuit of connection wires, and the manufacturing method thereof.
BACKGROUND OF THE INVENTION
The photo sensing devices such as photo couplers, photo sensors are extensively used in optical-based signal transmission system such as fiber communication, mouse or computer control systems. For examples, the related technologies are disclosed in Taiwan Pat. No. 254484 with title “Photo coupler device” and 289804 with title “Photo coupler apparatus”
FIG. 1A
shows a top view of prior art photo sensing device and
FIG. 1B
shows a sectional view along line A—A in FIG.
1
A. The photo sensing device, such as a photo coupler, comprises at least a light emitter
13
(for example, a light emitting diode, LED) and a light receiver
15
(for example, a photo diode, PD). The light emitter
13
and the light receiver
15
are fixed to two separate inner lead
139
(fourth inner lead) and inner lead
159
(first inner lead) of a leadframe. The LED
13
is connected to a sixth inner lead
137
through a connection wire
135
. The anode and cathode of the PD
15
are connected to second inner lead
151
and third inner lead
157
through connection wires
153
and
155
. Moreover, a semi-sphere encapsulating epoxy
17
and a sealing shell
11
are covered on the LED
13
, the LD
15
and the connection wires
135
,
153
and
155
to prevent short circuit of the connection wires. As indicated by the phantom line, the light generated by the LED
13
is received by the PD
15
to generate corresponding electric signal.
However, in above photo sensing device, the most light received by the PD
15
is reflection light of the LED
13
. The response of the photo sensing device is deteriorated.
FIG. 2
shows a sectional view of another prior art photo sensing device, wherein the fourth inner lead
239
of the leadframe is modified to lift the position of the LED
23
. The LED
23
is placed on the PD
25
mounted on the first inner lead
259
. Therefore, the light-receiving area of the PD
25
is increased and the response of the photo sensing device is enhanced.
However, in above photo sensing device, the distance between the LED
25
and the PD
23
is critical. The voltage endurance and isolation is poor when the encapsulating epoxy is excessively thin. The photo response is not satisfactory when the encapsulating epoxy is excessively thick. Moreover, the encapsulating epoxy is formed after the PD
25
and the LED
23
are mounted, therefore, the connection wires
235
and
255
have the risk of short circuit.
It is an object of the prevent invention to provide a photo sensing device having an encapsulating epoxy with easily adjustable height. The voltage durability and photo response are enhanced
It is another object of the prevent invention to provide a photo sensing device, wherein the photo emitter can be easily mounted and the height of the photo emitter can be easily controlled.
In one aspect of the present invention, a surface-emitting LED with anode and cathode on same surface is mounted on a top front surface of an encapsulating epoxy. The light of the surface-emitting LED can be directly received by a photo receiver and the photo response is enhanced.
In another aspect of the present invention, the photo receiver and the connection wires thereof are enclosed by an encapsulating epoxy and then the photo emitter is mounted on the encapsulating epoxy, the short circuit problem is prevented.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing, in which:
REFERENCES:
patent: 3727064 (1973-04-01), Bottini
patent: 4412135 (1983-10-01), Kashihara
patent: 5164930 (1992-11-01), Sugiura
patent: 5171985 (1992-12-01), Kawaguchi
patent: 6060337 (2002-05-01), Kobachi et al.
patent: 2002/0026108 (2002-02-01), Colvin, Jr.
Chang Chia Chen
Chuang Feng Ju
Lin Ming-Der
Tseng Wen Liang
Chaudhuri Olik
Opto Tech Corporation
Rosenberg , Klein & Lee
Vesperman William C
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