JP2003084173A - Bidirectional optical transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface mount type bi-directional optical transmission device which is adaptive to reflowing. SOLUTION: On the surface of the housing 11 of an optical transmission module 10, a reception hole that couples a connector 20a holding an end of an optical fiber 20 for one-core transmission and reception is formed. In the housing 11, the bi-directional optical transmission device 19 is stored and a block 15 having a light receiving element 13 and a light emitting element 14 mounted back to back on two opposite surface of the rectangular block 15 is mounted on a wiring board 12. The light receiving element 13 and light emitting element 15 are sealed with mold resin 17. The external wall surface 17a of the mold resin 17 on the side of the optical fiber 20 is plane and the external wall surface 17b on the opposite side has nearly the same curved concave surface as an arc, an elliptic arc, or a parabola as section parallel to the board 12. A connection terminal 12a exposed on the reverse surface of the housing 11 is suitable for surface mounting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bidirectional optical transmission device which is applied to optical transmission transceivers, optical minijacks, and the like, and is particularly suitable for short-distance transmission.

[0002]

2. Description of the Related Art Optical fibers have a small diameter (about 0.1 mm in diameter), are lightweight (the specific gravity of glass is about 1/4 of the specific gravity of copper), and are excellent in flexibility (radius of curvature of several cm or less), electromagnetic. No induction, strong crosstalk, low loss (eg 1dB / k)
m) High-bandwidth transmission is possible and there are few resource problems. Therefore, the optical fiber cable transmission system is used in the field of WAN, which is the field of public communication, as well as the transmission system and data bus of the in-station configuration called LAN. It has a wide range of application fields such as, data link, and various measurement control systems.

Further, in the field of personal use called PAN, a diameter of about 1 m is conventionally used as a bidirectional optical transmission module applied to an optical transceiver transceiver, an optical minijack and the like.
A two-core optical fiber cable equipped with a dedicated optical fiber for reception using the core wire of m as an optical transmission line, and a light-receiving device including a light-receiving element on the receiving fiber side at this cable end A two-core bidirectional optical transmission module that performs signal processing by installing (Rx) on the transmission fiber side and a light emitting side device (Tx) including a light emitting element in a housing is used, and the light emitting side device (Tx) is also used.
x) and the light-receiving side device (Rx) are installed in a housing connected to both ends of a one-core optical fiber cable, and there is an optical transmission module for one-way transmission (here, the optical transmission device is housed in the housing). There was no bidirectional optical transmission device applicable to a small bidirectional optical transmission module that transmits and receives using a single-core optical fiber cable.

An example of a conventional two-core bidirectional optical transmission module will be described. First, the configuration will be described.
FIG. 4 is a sectional view of a conventional two-core bidirectional optical transmission module. In FIG. 4, reference numeral 71 denotes a two-core bidirectional optical fiber cable in which a receiving optical fiber 71a and a transmitting optical fiber 71b are bundled by using a plug component 71c. 80 is a two-core bidirectional optical transmission module,
1 is the housing. 82 is an optical fiber 71a,
71b is a partition having an opening for holding the tip portion of 71b. 8
3 is a light emitting side device (Tx) arranged on the transmitting optical fiber 71b side, and 84 is a light receiving side device (Rx) arranged on the receiving optical fiber 71a side.

The light emitting side device 83 is an IC of 86 for converting a logic level electric signal into a light emitting element driving signal.
And a light emitting element 87, which is an LED or LD for converting a modulated electric signal into an optical signal, are mounted on a lead frame 85 and sealed with a translucent resin 88. In the light-receiving side device 84, 89 light-receiving ICs in which a photodiode for converting an optical signal into an electric signal and an IC for further amplifying to a logic level are integrated are mounted on a lead frame 85 and sealed with a translucent resin 88. It has been stopped. Housing 8
An input / output connection terminal (not shown) is provided so as to project from the outer wall of No. 1 and is electrically connected to the lead frame 85.

Next, the operation of the optical transmission module 80 will be described. The optical signal transmitted from the communication partner side through the receiving optical fiber 71a passes through the transparent resin 88, is input to the light receiving IC 89, and is converted into an electric signal. On the other hand, I
The light emitted from the light emitting element 87 via C86 is transparent resin 8
After passing through No. 8, the optical fiber enters into the transmission side optical fiber 71b, is transmitted therethrough, and is sent out to the communication partner side.

[0007]

However, such a conventional two-core bidirectional optical transmission module requires a two-core optical fiber cable. When connecting the two-core cable to the module, care must be taken not to confuse the input and output directions. In addition, the two-core cable has a problem of usability that it is less likely to bend than a one-core cable. Further, since the light emitting side device and the light receiving side device are separately installed in the optical transmission module, it is difficult to miniaturize the module. Furthermore, since both devices are insertion mount type components that use lead frames,
A lot of mounting man-hours are required.

The present invention has been made to solve such a conventional problem, and an object thereof is to reduce the size of a bidirectional optical transmission device by integrating a light receiving element and a light emitting element, and 1-core optical fiber is used as the transmission line,
It is an object of the present invention to provide a surface mount type bidirectional optical transmission device capable of reflow.

[0009]

Means for Solving the Problems The means of the present invention for achieving the above-mentioned object is to provide a bidirectional optical transmission device having a light emitting element for transmitting and receiving an optical signal by an optical fiber and a light receiving element, and opposing rectangular blocks. The above-mentioned block in which the light emitting element and the light receiving element are mounted back to back on two surfaces is mounted on a wiring board and the entire block is resin-molded, and a reflection film is formed on the outer wall surface of the molding resin in the emitting direction of the light-emitting element. The light emitted from the light emitting element is reflected in the opposite direction by the reflective film, and a single-core optical fiber is used as an optical transmission line.

Further, the cross-sectional shape of the outer wall surface of the molding resin on which the reflection film is formed and which is parallel to the wiring board is a convex shape approximate to an arc, an elliptic arc or a parabola.

The reflective film is coated with resin or the like.

Further, it is characterized in that a connection terminal is provided on one surface of the wiring board.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A one-core bidirectional optical transmission module according to an embodiment of the present invention will be described in detail below with reference to the drawings. 1 is a perspective view of a one-core bidirectional optical transmission module and an optical fiber according to an embodiment of the present invention, FIG. 2 is a top view of an optical transmission device of this one-core bidirectional optical transmission module, and FIG. It is sectional drawing which shows the AA cross section.

First, the structure of this optical transmission module will be described. In FIG. 1, reference numeral 10 is a surface-mounting type one-core bidirectional optical transmission module, and 20 is a one-core optical fiber as a transmission path for transmitting an optical signal bidirectionally. Reference numeral 19 is a bidirectional optical transmission device, 11 is a housing of the optical transmission module 10 which is a resin molded product accommodating the bidirectional optical transmission device 19, and the housing 11 has a penetrating member for guiding and holding the tip of the optical fiber 20. A partition wall (not shown) having a hole and a receiving port for the connector 20a are formed.

Next, the configuration of the bidirectional optical transmission device 19 will be described with reference to FIGS. Reference numeral 12 is a wiring board made of ceramic or glass epoxy, and a wiring pattern is formed on the board 12. A half-cut through hole that is electrically connected to a part of the wiring pattern and is formed on one side surface of the substrate 12 is exposed from the lower surface of the housing 11 and serves as a connection terminal 12a. Reference numeral 13 is a light receiving element such as a photodiode or a photodiode integrated with an amplifier circuit.

Reference numeral 14 is a light emitting element which is a point emission or surface emission LED. Reference numeral 15 is a rectangular block as a sub-mount block, which is made of metal or plastic, and whose surface is optionally insulated from the ground to form electrodes, and which is a sub-mount block. The light emitting element 14 and the light emitting element 14 are mounted back to back by a reverse mounting method to be integrated. The block 15 is mounted on the substrate 12, and the light receiving element 13 and the light emitting element 14 are connected to the wiring pattern of the substrate 12 via the block 15, respectively. In this way, the light emitting element 14 is mounted so as to emit light in the opposite direction to the optical fiber 20.

Reference numeral 16 denotes a drive IC for controlling the light emitting element 14, which is mounted on the substrate 12 in front of the light receiving element 13. Reference numeral 17 denotes a molding resin made of a translucent epoxy resin or the like which protects the mounting portions of the light receiving element 13 and the light emitting element 14 from moisture and dust. One outer wall surface 17a of the mold resin 17 facing the end surface of the optical fiber 20 is a flat surface, and the other outer wall surface 17b has a convex shape whose cross-sectional shape parallel to the substrate 12 is substantially equal to an arc, an elliptic arc, or a parabola. Curved surface. 18 is an outer wall surface 17b
It is a reflective film formed by metal deposition or the like. Reflective film 18
A coating film 18a made of resin or the like is applied so as to cover the.

Next, the operation of this bidirectional optical transmission device will be described with reference to FIG. As shown by the dotted arrow, the outside light emitted from the light emitting element 14 is reflected by the reflection film 18 and travels toward the optical fiber 20 in the direction opposite to the emitted light and is transmitted to the other party via the optical fiber 20. Since a part of the light inside (solid arrow) is blocked by the block 15, it does not enter the light receiving element 13 due to near-end reflection at the end face of the optical fiber 20. The light received from the optical fiber 20 is directly incident on the light receiving element 13 and is converted into an electric signal without being blocked by other components.

Next, the effect of the embodiment of the present invention will be described. Since the light receiving element 13 and the light emitting element 14 are integrated to reduce the size of the light receiving and emitting element, the bidirectional optical transmission device 18, and thus the optical transmission module 10 such as an optical transceiver and an optical jack can be downsized. became. Also,
Since the light emitting element 13 and the light receiving element 14 are solidified with the mold resin 17, it is advantageous in terms of dustproofness and moistureproof, and deterioration of the elements can be prevented. Since the outer wall surface 17b of the mold resin 17 is a convex curved surface, the reflection film 18 is a concave surface, and the light emitted from the light emitting element 14 to the opposite side of the optical fiber 20 can be efficiently reflected toward the optical fiber 20. It was Since the reflection film 18 is coated with resin or the like to form the coating film 18a, it is possible to prevent the reflection film from being oxidized or deteriorated.

Since the light emitted from the light emitting element 14 does not enter the light receiving element 13, deterioration of the S / N ratio of the light receiving element 13 can be prevented. On the other hand, when the bidirectional optical transmission device 19 receives light, sufficient light reaches the light receiving element 13 and communication is stabilized. By adopting the block 15, the light receiving element 13 is mounted on the substrate 12
The IC 16 does not interfere with the light incident on the light receiving element because it can be mounted sufficiently separated from the surface. Since the distance between the core wire of the optical fiber 20 and the optical transmission device 19 can be sufficiently shortened, more effective optical transmission can be performed. Since the bidirectional optical transmission module 10 can configure the connection terminal 12a in the surface mounting type by using the substrate 12, the reflow process can be adopted when mounting on the motherboard of the communication device, which contributes to the cost reduction of the communication device. Also, because the light emission and reception can be gathered in a narrow range,
The single-core optical fiber 20 can be adopted. Therefore, it is not necessary to pay attention to the direction of input and output when mounting the fiber, and since the optical fiber 20 is easily bent, it is easy to use and the cable cost can be suppressed.

[0021]

As described above, according to the present invention,
The rectangular block having a light emitting element and a light receiving element mounted back to back on two opposing sides of the rectangular block is mounted on a wiring board, the entire rectangular block is resin-molded, and a molded resin outer wall surface facing the light emitting element. Since a convex curved surface was formed on the reflective film, a single-core optical fiber could be used as an optical transmission line, and a miniaturized bidirectional optical transmission device was obtained.

Further, since the light emitted from the light emitting element is reflected by the reflecting film toward the opposite optical fiber, the emitted light is prevented from entering the light receiving element, and the S / N ratio of the light receiving element is prevented. Could be prevented from worsening. Since there is no component that blocks the light receiving element, it is possible to stably and sufficiently receive light from the communication partner to the light receiving element. Since the distance between the optical fiber core wire and the optical transmission device can be sufficiently shortened, more effective optical transmission can be performed.

Further, since the light receiving element and the light emitting element are covered with the molding resin, the elements are protected from humidity and dust environment. Further, since the reflective film is covered with the coating film, deterioration of the reflective film can be prevented.

Further, since the bidirectional optical transmission device is constructed on the substrate and has the surface mounting type having the connection terminal exposed on the outer wall surface of the housing, the optical transmission module accommodating the bidirectional optical transmission device is used for communication equipment or the like. The cost can be reduced by effectively utilizing the reflow process when mounting on a circuit board.

[Brief description of drawings]

FIG. 1 is a perspective view of a one-core bidirectional optical transmission module and an optical fiber according to an embodiment of the present invention.

2 is a top view of a bidirectional optical transmission device of the single-core bidirectional optical transmission module in FIG. 1. FIG.

3 is a cross-sectional view showing a cross section taken along the line AA of FIG.

FIG. 4 is a cross-sectional view of a conventional two-core bidirectional optical transmission module.

[Explanation of symbols]

10 Optical transmission module 12 substrates 12a connection terminal 13 Light receiving element 13a light receiving part 14 Light emitting element 15 blocks 17 Mold resin 18 Reflective film 18a coating film 19 Two-way optical transmission device 20 optical fibers

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasuaki Kayonuma             Yamanashi Prefecture Fujiyoshida City Kamigure 1-23-1             Citizen Electronics Co., Ltd. F-term (reference) 2H037 AA01 BA02 BA11 CA38 DA03                       DA36                 5F089 AA01 AB20 AC10 AC13 AC15                       AC17 CA20 FA03 FA05

Claims (4)

[Claims] 1. A bidirectional optical transmission device comprising a light emitting element for transmitting and receiving an optical signal by an optical fiber and a light receiving element, wherein the block in which the light emitting element and the light receiving element are mounted back to back on two opposite sides of a rectangular block. The block is mounted on a wiring board and the whole block is resin-molded, and a reflection film is formed on the outer wall surface of the molding resin in the emission direction of the light emitting element, and the light emitted from the light emitting element is directed in the opposite direction by the reflection film. A two-way optical transmission device characterized in that a single-core optical fiber is used as an optical transmission line while being reflected to. 2. The cross-sectional shape of the outer wall surface of the molding resin on which the reflection film is formed, which is parallel to the wiring board, is a convex shape approximate to an arc, an elliptic arc, or a parabola. 1. The bidirectional optical transmission device according to 1. 3. The bidirectional optical transmission device according to claim 1, wherein the reflective film is coated with a resin or the like. 4. The bidirectional optical transmission device according to claim 1, further comprising a connection terminal on one surface of the wiring board.