JPH11196055A - Optical transceiver - Google Patents

Abstract

(57) [Problem] To provide an optical transceiver that realizes miniaturization, high speed, and high sensitivity by suppressing signal interference such as external noise. SOLUTION: A signal terminal of a light emitting element 1 and a signal terminal of a light receiving element 5 are electrically connected via a signal wiring 10C of a flexible substrate 10 having a ground layer 10A disposed outside a flexible insulating layer 10B, and a ground is provided. The layer 10A is connected to the ground layer to form an electromagnetic shield surrounding the signal terminal connection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transceiver for use in a communication device using an optical fiber, and more particularly, to miniaturization, high speed, and high sensitivity by suppressing signal interference such as external noise. It relates to an optical transceiver.

[0002]

2. Description of the Related Art Conventionally, an optical transceiver used in a communication device using an optical fiber includes a light emitting element such as a laser diode (LD) for photoelectrically converting an electric signal to an optical signal, and a transmission for driving the light emitting element. (Drive) circuit, a light receiving element such as a photodiode (PD) for photoelectrically converting an optical signal into an electric signal, and a receiving circuit for amplifying and waveform shaping the electric signal photoelectrically converted by the light receiving element. The element driving circuit and the light receiving element receiving circuit are mounted on a single common board and housed in a housing.

In such an optical transmitter / receiver, the electric signal photoelectrically converted by the light receiving element is a very small signal of several μA. Therefore, if there is another electronic circuit or wiring near the optical transmitter / receiver, signal interference may occur. This causes a problem that the reception sensitivity is reduced and the reception sensitivity is reduced. In addition, since a signal terminal connecting the drive circuit and the light emitting element, or an interference signal picked up by the signal terminal connecting the receiving circuit and the light receiving element also causes a decrease in transmission / reception characteristics, the entire light receiving element, A shield is provided by surrounding the entire light emitting element with a metal plate or the like. 2. Description of the Related Art In recent years, optical transceivers have been required to have smaller transmission speed, higher sensitivity, and higher quality transmission / reception characteristics.

FIG. 6 shows a conventional optical transceiver, in which a light emitting element 1 for generating an optical signal corresponding to an electric signal and a light emitting element 1 are shown.
, A light receiving element 5 for generating an electric signal corresponding to an optical signal, a receiving circuit 6 for amplifying an electric signal output from the light receiving element 5 and shaping the waveform, and a driving circuit for the light emitting element 1 2 and a circuit board 4 on which a receiving circuit 6 for the light receiving element 5 is mounted. The light emitting element 1, the light receiving element 5, and the circuit board 4 are housed in a housing 8.

The light emitting element 1 is connected to the circuit board 4 by fixing the signal terminal 1A to the connection section 3, and the light receiving element 5 is connected to the circuit board 4 by fixing the signal terminal 5A to the connection section 7. It is connected. The light emitting element 1 and the light receiving element 5 are configured to be positioned at predetermined positions by fixing the metal holders 1B and 5B to the housing 8. The circuit board 4 is connected to a ground layer (not shown) on the back surface of the board via a through hole 4A.

FIG. 7 shows a side view of a conventional optical transceiver.
Since the signal terminal 1A from the metal holder 1B of the light emitting element 1 to the connection part 3 with the circuit board 4 is susceptible to signal interference, this part or the whole light emitting element 1 is surrounded by a metal plate and shielded, The shield 5 is similarly provided at the signal terminal 5A at the connection portion 7 with the circuit board 4 (a metal plate is not shown in the figure). The drive circuit 2 is provided on the front and back surfaces of the circuit board 4.

[0007]

However, according to the conventional optical transmitter / receiver, it is difficult to secure a space for mounting a metal plate for shielding as the demand for miniaturization and higher density progresses. There is a limit to the improvement of characteristics. Accordingly, it is an object of the present invention to provide an optical transceiver capable of miniaturizing, increasing speed, and increasing sensitivity by suppressing signal interference such as external noise.

[0008]

According to the present invention, there is provided an optical transmitter / receiver having a light receiving / emitting element in which transmission / reception of an optical signal is controlled by a transmission / reception circuit formed on a circuit board. An optical transceiver provided between a light emitting element and the transmitting / receiving circuit, electrically connecting a signal terminal connection part of the light receiving / emitting element and input / output wiring of the transmitting / receiving circuit, and having a flexible shield means for electromagnetically shielding. provide.

In the above-mentioned optical transceiver, the flexible shield means includes a flexible insulator, and a signal wiring embedded in the insulator and connecting the light emitting / receiving element and the transmission / reception circuit via a signal terminal connection portion. And a ground layer provided outside the insulator, and the electromagnetic shield is preferably formed by covering the signal terminal connection portion and connecting the ground layer to the ground layer of the circuit board. Or you may comprise so that a signal terminal connection part may be enclosed in a box shape.

According to another aspect of the present invention, there is provided an optical transceiver having a light emitting and receiving element in which transmission and reception of an optical signal of the light emitting and receiving element are controlled by a transmitting and receiving circuit formed on a circuit board. Provided is an optical transceiver having a flexible shield means formed integrally with a substrate and electromagnetically shielding a signal terminal connection portion of the light emitting / receiving element and an input / output wiring of the transmission / reception circuit.

In the above-mentioned optical transceiver, the flexible shield means is preferably constituted by a conductive sheet surrounding the signal terminal connection portion of the light emitting / receiving element and the input / output wiring of the transmission / reception circuit.

[0012]

FIG. 1 shows an optical transceiver according to a first embodiment of the present invention, in which a flexible substrate 10 covering a connection portion 3 for connecting a signal terminal of a light emitting element 1 to a circuit board 4 is shown. The flexible substrate 10 includes a ground layer 10 </ b> A disposed outside and a flexible insulating layer 1.
0B, and a signal wiring 10C provided in the insulating layer 10B. The signal wiring 10C is configured to have a size larger than the circuit mounting portion, and is fixed to the metal holder 1B of the light emitting element 1 via the connection member 13. I have. The ground layer 10A of the flexible substrate 10 is connected to a ground layer (not shown) via a through hole 4B. Further, the portion of the connection portion 7 for connecting the signal terminal of the light receiving element 5 and the circuit board 4 is also covered with the flexible substrate 10. The other components are denoted by the same reference numerals as those in FIG. 6, and thus redundant description will be omitted.

FIG. 2 shows a side cross section of the optical transceiver 9A. The flexible substrate 10 has one end on the light emitting element 1 side fixed to a metal holder 1B via a connecting member 13 and a flexible circuit board 10 on the drive circuit 2 side. Is fixed on the circuit board 4, and connects the signal terminal of the light emitting element 1 to the signal wiring 10C. After connecting the signal wiring 10C to the connection part 3, the metal holder 1B and the connection part 3 are connected. It is formed by bending the flexible substrate 10 so as to surround it. In FIG. 2, the metal holder 1B side is folded back on the back surface of the circuit board 4 and connected to a ground layer (not shown), and the drive circuit 2 side is formed with a through hole (not shown) on the circuit board 4. An electromagnetic shield is formed by connecting to an earth layer through the intermediary. In addition, the connection portion 7 for connecting the signal terminal of the light receiving element 5 and the circuit board 4 has the same configuration.

FIG. 3 shows the flexible substrate 1 shown in FIG.
0 indicates a III-III portion, and the signal wiring 10C provided in the insulating layer 10B is shielded by the ground layer 10A, so that signal interference due to external noise or the like can be prevented and the optical transmission / reception characteristics can be improved. . Further, since a metal plate for shielding is not required, the size of the optical transceiver can be reduced.

In the above-mentioned optical transceiver 9A, the light emitting element 1 and the light receiving element 5 are connected to the circuit board 4 using the flexible substrate 10 having the ground layer 10A on the outside, and the signal terminal connecting portion is covered and the ground is connected to the ground. Layer 10A
Since the electromagnetic shield formed by the above shields from external noise and the like, a space for providing a shield plate becomes unnecessary.
In the first embodiment, the ground layer 10A is connected to the ground layer on the back surface of the circuit board 4 by bending the metal holder 1B side not connected to the circuit board 4; If this is not possible, the electromagnetic shield can be strengthened by connecting the ground layer 10A to the ground layer by soldering or crimping.

A box-shaped shield may be formed by forming a notch at the end of the flexible substrate 10 and plating the notch and joining the flexible substrates 10 to each other. Can make the shield stronger.

FIG. 4 shows an optical transceiver according to a second embodiment of the present invention, in which a flexible substrate 20 formed of a conductive sheet having a ground layer 20A is connected to a light emitting element 1 and a light receiving element 5. Circuit board 4 corresponding to
Are provided integrally. This flexible substrate 20
Is formed to have a size that encompasses a wide area of the region between the metal holder 1B of the light emitting element 1 and the connection portion 3 between the signal terminal 1A and the region of the light receiving element 5 between the metal holder 5B and the connection portion 7 of the signal terminal 5B. Have been. Light emitting element 1
And a strip-shaped notch 11 formed at a portion connected to the light receiving element 5, and a plating layer 1 such as a solder from the terminal portion to the inside of the conductive sheet provided with the strip-shaped notch 11.
2 The ground layer 20A is connected to a ground layer (not shown) via the through hole 4B. The other components are denoted by the same reference numerals as those in FIG.

FIG. 5 shows a side cross section of the optical transceiver 9B. The flexible substrate 20 has a strip-shaped notch 11 to increase the contact area with the metal holders 1B and 5B. The ground layer 20A and the metal holders 1B and 5B are electrically connected by forming the plating layer 12 from the terminal portion to the inside of the conductive sheet, and the terminal portion (outer lead) located on the light emitting element 1 side of the drive circuit 2 ). In addition, the connection portion 7 for connecting the signal terminal 5A of the light receiving element 5 and the circuit board 4 has the same configuration.

Since the flexible substrate 20 of the optical transceiver 9B covers not only the terminal joints of the light emitting element 1 and the light receiving element 5 but also the terminals of the drive circuit 2 and the wiring, the flexible circuit board 20 is shielded. And the signal interference can be reduced. Further, by providing a plating layer 12 from the terminal portion to the inside of the conductive sheet in which the strip-shaped notch 11 is formed and electrically connecting to the light emitting element 1 and the light receiving element 5, the shield is further strengthened. Can be.

The optical transceiver having the above-mentioned flexible substrate can be used as an optical transceiver for high-speed digital optical communication and high-frequency analog optical communication. The ground layer disposed outside the flexible substrate can be provided by a foil, a vapor-deposited film, or a net made of copper, aluminum, or the like in the case of high frequency. In the case of low frequency, it can be provided by a material having high magnetic permeability. In addition to these materials, ceramic materials and organic materials that absorb electromagnetic waves can be used. Further, a ground layer capable of supporting a wide band can be formed by combining a plurality of the above-mentioned materials.

[0021]

As described above, according to the optical transceiver of the present invention, the signal terminals of the light emitting element and the light receiving element are electrically connected via the flexible substrate provided with the ground layer, and the ground layer is connected to the ground layer. Since a shield is formed to connect and surround the signal terminal, signal interference such as external noise can be suppressed, and miniaturization, high speed, and high sensitivity can be realized.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an optical transceiver according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an optical transceiver according to the first embodiment of the present invention.

FIG. 3 is a sectional view taken along the line III-III in FIG. 2;

FIG. 4 is an explanatory diagram showing an optical transceiver according to a second embodiment of the present invention.

FIG. 5 is an explanatory diagram showing an optical transceiver according to a second embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a conventional optical transceiver.

FIG. 7 is an explanatory diagram showing a conventional optical transceiver.

[Explanation of symbols]

 1, light emitting element 1A, signal terminal 1B, metal holder 2, drive circuit 3, connection part 4, circuit board 4A, through hole 4B, through hole 5, light receiving element 5A, signal terminal 5B, metal holder 6, receiving circuit 7, connection part 8, housing 9, optical transceiver 9A, optical transceiver 9B, optical transceiver 10, flexible substrate 10A, ground layer 10B, insulating layer 10C, signal wiring 11, notch 12, plating layer 13, connection member 20, flexible board 20A, ground layer

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI H04B 10/02 10/18

Claims (5)

[Claims] 1. An optical transceiver having a light emitting and receiving element whose transmission and reception of an optical signal is controlled by a transmitting and receiving circuit formed on a circuit board, wherein the optical transceiver is provided between the light receiving and emitting element and the transmitting and receiving circuit, and An optical transceiver comprising a flexible shield means for electrically connecting a signal terminal connection portion of an element to an input / output wiring of the transmission / reception circuit and for electromagnetically shielding. 2. The flexible shield means includes: a flexible insulator; and a signal wiring embedded in the insulator to connect the light emitting / receiving element and the transmission / reception circuit via the signal terminal connection portion. And a ground layer provided outside the insulator, wherein the electromagnetic shield is formed by covering the signal terminal connection portion and connecting the ground layer to a ground layer of the circuit board. The optical transceiver according to the item. 3. The optical transceiver according to claim 1, wherein said flexible shield means is configured to surround said signal terminal connection portion in a box shape. 4. An optical transceiver having a light emitting and receiving element in which transmission and reception of an optical signal of the light emitting and receiving element is controlled by a transmitting and receiving circuit formed on a circuit board, wherein the light transmitting and receiving element is formed integrally with the circuit board. An optical transceiver comprising: a flexible shield means for electromagnetically shielding a signal terminal connection portion of an element and an input / output wiring of the transmission / reception circuit. 5. The optical transceiver according to claim 4, wherein said flexible shield means is constituted by a conductive sheet surrounding a signal terminal connection portion of said light emitting / receiving element and an input / output wiring of said transmission / reception circuit.