Optical waveguides – With disengagable mechanical connector – Optical fiber to a nonfiber optical device connector
Reexamination Certificate
2000-11-21
2003-07-08
Sanghavi, Hemang (Department: 2874)
Optical waveguides
With disengagable mechanical connector
Optical fiber to a nonfiber optical device connector
C250S551000, C250S239000, C257S082000
Reexamination Certificate
active
06588946
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical coupling device having a function of electrically isolating an input side and an output side from each other by converting an electrical signal into an optical signal by means of a light emitting device and converting the optical signal back into the electrical signal by means of a light receiving device.
2. Description of the Related Art
An opposed-type optical coupling device in which a light emitting device and a light receiving device are arranged to oppose each other is known in the art.
FIG. 20
illustrates an optical coupling device
2000
having such a structure. The optical coupling device
2000
includes a light emitting device
1
and a light receiving device
2
which are mounted on header sections of respective lead frames
14
. The light emitting device
1
and the light receiving device
2
are wire-bonded to the respective lead frames
14
via gold wire
3
. The light emitting device
1
, the light receiving device
2
and the lead frames
14
are molded together with a light transmissive resin
5
into a rectangular parallelepiped shape. The rectangular parallelepiped structure is further molded in a light blocking resin
16
. Thus, the resulting device has a double-molded structure.
FIG. 21
illustrates a structure of another opposed-type optical coupling device
2100
known in the art. In the optical coupling device
2100
, substantially U-shaped insulative substrates
2106
A and
2106
B are used instead of the lead frames
14
. The light emitting device
1
and the light receiving device
2
are placed respectively in the substantially U-shaped insulative substrate
2106
A on the light emitting side and the substantially U-shaped insulative substrate
2106
B on the light receiving side. The two substantially U-shaped insulative substrates
2106
A and
2106
B are attached together so that the devices
1
and
2
, opposing each other, are optically coupled together. Wiring patterns
2104
A and
2104
B are provided on the insulative substrates
2106
A and
2106
B for the devices
1
and
2
, respectively. In
FIG. 21
, a line
2104
C running substantially through the center of the optical coupling device
2100
denotes an adhesive with which the insulative substrates
2106
A and
2106
B are attached together.
FIG. 22
illustrates a structure of still another optical coupling device
2200
using insulative substrates. The optical coupling device
2200
includes a substantially U-shaped insulative substrate
2206
A and a plate-like insulative substrate
2206
B. Wiring patterns
2204
A and
2204
B are provided on the substantially U-shaped insulative substrate
2206
A, and a wiring pattern
2204
C is provided on the plate-like insulative substrate
2206
B. The wiring pattern
2204
A extends from an area of the substantially U-shaped insulative substrate
2206
A on which the light emitting device
1
is mounted to the outside of the optical coupling device
2200
, where the wiring pattern
2204
A functions as a soldering section. The wiring pattern
2204
B extends from the bottom of one end of the plate-like insulative substrate
2206
B to the outside of the optical coupling device
2200
, where the wiring pattern
2204
B functions as a soldering section. The wiring pattern
2204
C extends from an area of the plate-like insulative substrate
2206
B where the light receiving device
2
is mounted to the bottom of one side surface of the plate-like insulative substrate
2206
B. The plate-like insulative substrate
2206
B is structurally connected to the wiring patterns
2204
A and
2204
B via solder bumps
2208
A and
2208
B. The solder bump
2208
B electrically connects the wiring pattern
2204
C to the wiring pattern
2204
B.
However, when a lead frame is used in an opposed-type optical coupling device, the following problems arise. The thickness of a lead frame is 0.2 mm at minimum. For the light emitting side and the light receiving side in combination, a total thickness of 0.4 mm is required for the lead section, whereby it is difficult to reduce the overall thickness of the optical coupling device. For example, in the conventional example illustrated in
FIG. 20
, which employs the double-molded structure, the thickness of the optical coupling device
2000
is currently 2.1 mm at minimum.
Moreover, in the optical coupling device
2000
, an electrical signal is first transferred to the light emitting side lead frame
14
and then to the light emitting device
1
mounted on the header section of the light emitting side lead frame
14
. The electrical signal is converted into an optical signal at the junction plane
1
A of the light emitting device
1
, and then propagated to the light receiving device
2
. The optical signal which has been emitted from the junction plane
1
A of the light emitting device
1
toward a side surface thereof is absorbed by the light transmissive resin
5
, whereby substantially no portion of the optical signal reaches the light receiving device
2
. Moreover, substantially all of the optical signal which has reached the periphery of the light transmissive resin
5
is absorbed by the light blocking resin
16
and thus is not propagated to the light receiving device
2
. Thus, the transmission efficiency is poor in this conventional example.
The conventional example illustrated in
FIG. 21
, which does not use a lead frame, is quite useful in reducing the overall thickness of the optical coupling device. However, in this structure, it is difficult to solder the wiring patterns
2104
A and
2104
B to the insulative substrates
2106
A and
2106
B, respectively, thereby complicating the production process. Moreover, the devices
1
and
2
are mounted in the substantially U-shaped insulative substrates
2106
A and
2106
B, respectively, which makes the die-bonding or wire-bonding process more difficult.
The conventional example illustrated in
FIG. 22
is also quite useful in reducing the overall thickness of the optical coupling device. However, it is necessary to make an electrical connection between the wiring pattern
2204
C of the upper, plate-like insulative substrate
2206
B and the wiring pattern
2204
Bon the lower, substantially U-shaped insulative substrate
2206
A, thereby complicating the production process. Moreover, since the devices are mounted in the lower, substantially U-shaped insulative substrate
2206
A, which makes the die-bonding or wire-bonding process more difficult.
SUMMARY OF THE INVENTION
According to one aspect of this invention, there is provided an optical coupling device, including: a light emitting device for converting an electric signal into an optical signal and outputting the optical signal; and a light receiving device for receiving the optical signal output from the light emitting device and converting the optical signal into the electric signal, wherein: the light emitting device has a light emitting surface for outputting the optical signal; the light receiving device has a light receiving surface for receiving the optical signal; and the light emitting device and the light receiving device are arranged so that the light emitting surface and the light receiving surface oppose each other, the optical coupling device further including: a first insulative substrate on which the light emitting device is mounted; and a second insulative substrate on which the light receiving device is mounted, wherein: the first insulative substrate has a first cross section; and the second insulative substrate has a second cross section; and at least one of the first cross section and the second cross section is substantially L-shaped.
In one embodiment of the invention, the first insulative substrate has a wiring pattern connected to the light emitting device; and the wiring pattern includes a soldering terminal section.
In one embodiment of the invention, the light emitting device is connected to the wiring pattern by way of wire bonding.
In one embodiment of the invention, the second insulative substrate has a wiri
Birch & Stewart Kolasch & Birch, LLP
Knauss Scott A
Sanghavi Hemang
Sharp Kabushiki Kaisha
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