JP2994470B2 - Optical transmission equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission device for transmitting and receiving an optical signal via an optical fiber cable.

When laser light used for optical communication directly enters human eyes, there is a high risk that the retina or the like may be damaged. Therefore, in general, in an optical communication system, when an optical fiber cable connected between optical transmission devices is disconnected,
Until the fiber optic cable returns to normal condition
It is necessary to prevent an optical signal that is harmful to human eyes from being output.

[0003]

2. Description of the Related Art A conventional optical transmission apparatus detects whether an optical fiber cable is in a normal state or a disconnected state by detecting the presence or absence of an optical signal input to a receiving unit. When there is no optical signal input to the unit, the output operation of the transmitting unit of the station is stopped.

[0004] Therefore, when the optical fiber cable connecting the two stations is disconnected, the receiving unit of the station receiving the output from the optical fiber cable stops receiving the optical signal, and the transmitting unit stops. Output operation is stopped. Then, since the optical signal is not input to the receiving unit in the other station, the output operation of the transmitting unit also stops.

[0005] In this way, in both stations to which the disconnected optical fiber cable is connected, the output operation of the laser signal is stopped.

[0006]

However, in the conventional optical transmission device as described above, the transmission unit stops the optical output operation even after the optical fiber cable is restored to the normal state. Therefore, after the disconnection of the optical fiber cable is restored, the optical output from the transmission unit must be manually restarted, and there is a disadvantage that it takes time and effort to restore the optical output.

[0007] The present invention has solved such a conventional drawback, and has made it possible to automatically restore the optical output without causing any harm to human eyes when the optical fiber cable is disconnected. An object is to provide an optical transmission device.

[0008]

In order to achieve the above object, an optical transmission apparatus according to the present invention, as shown in FIG. 1, uses a first optical fiber 5 for transmitting an optical signal to a partner station. An optical signal transmitting unit 10 capable of selectively switching and outputting a normal optical signal and a low-level optical signal, and a second optical fiber 6 for transmitting an optical signal from the partner station. An optical signal receiving unit 20 for receiving a plurality of types of input optical signals, a detecting unit 9 for detecting a type of the optical signal received by the optical signal receiving unit 20, and a detection result of the detecting unit 9. In response, the optical signal transmission control means 4 for controlling the operation of the optical signal transmission unit 10 so as to switch the type of the optical signal output to the first optical fiber 5.
And characterized in that:

The low-level optical signal includes a first low-level optical signal and a second low-level optical signal. Does not detect either the normal optical signal or the first and second low-level optical signals, the optical signal transmitting unit 10 sends the first low-level signal to the first optical fiber 5. And the detecting means 9 outputs the first optical signal.
When the low-level optical signal is detected, the second low-level optical signal is output from the optical signal transmitting unit 10 to the first optical fiber 5, and the detection unit 9 outputs the second low-level optical signal. When a level optical signal is detected or when the detecting means 9 detects the normal optical signal, the normal optical signal is output from the optical signal transmitting section 10 to the first optical fiber 5. You may.

A plurality of optical signal transmitting units 100 and 101 for outputting a plurality of optical signals having different wavelengths to the optical fiber 300, and one of the plurality of optical signals input from the optical fiber 300. A plurality of optical signal receiving units 110 and 111 for receiving the
Detecting means 120 for detecting the presence / absence of reception of an optical signal of a specific wavelength which is least harmful to human eyes among the plurality of optical signals received at 111; The optical signal transmitting unit 1 outputs an optical signal other than the optical signal of the specific wavelength when the reception of the optical signal is not detected.
01 is stopped, and when the detection means 120 detects the reception of the optical signal of the specific wavelength, the optical signal transmitting unit 101 outputs an optical signal other than the optical signal of the specific wavelength.
And an optical signal transmission control means 130 for performing an output operation.

[0011]

The detecting means 9 detects the type of the optical signal received by the optical signal receiving section 20, and in response to the detection result, the optical signal transmission control means 4 outputs the signal to the first optical fiber 5. Switch the type of optical signal.

When the detecting means 9 detects neither the ordinary optical signal nor any of the first and second low-level optical signals, the optical signal transmission control means 4 outputs the first optical fiber 5
Output a first low-level optical signal from the optical signal transmitting unit 10 to the first optical fiber 5 when the detecting unit 9 detects the first low-level optical signal. 10 to output a second low-level optical signal. When the detecting means 9 detects the second low-level optical signal or when the detecting means 9 detects a normal optical signal, the first optical fiber 5 is output. On the other hand, the optical signal transmitting unit 10 outputs a normal optical signal.

When the detecting means 120 does not detect the reception of the optical signal of the specific wavelength, the output operation of the optical signal transmitting section 101 for outputting an optical signal other than the optical signal of the specific wavelength is stopped, and the detecting means 120 sets the specific wavelength. When the reception of the optical signal is detected, the optical signal transmitting unit 101 that outputs an optical signal other than the optical signal of the specific wavelength is caused to perform the output operation.

[0014]

An embodiment will be described with reference to the drawings.

FIG. 2 shows an optical transmission device according to a first embodiment of the present invention. This optical transmission device is provided for each station.

The optical transmission device of each station includes a transmitting unit 10 for converting an electric signal to an optical signal and transmitting the signal to another station, a receiving unit 20 for receiving an optical signal from another station and converting the signal to an electric signal, The filter 30 includes a filter 30 that filters and detects a specific electric signal output from the receiving unit 20 and a control unit 40 that controls an optical signal output operation of the transmitting unit 10.

The transmitting section 10 includes a light emitting section 11 for generating a laser light signal to be output to a first optical fiber cable 50 for transmitting an optical signal to a partner station,
And second driving circuits 12 and 13 for driving
And a monitor 14 for monitoring the output level of the optical signal output from the light emitting unit 11 in order to keep the output level constant.
And

The first drive circuit 12 includes a terminal (not shown).
A driving current is output to the light emitting unit 11 based on the electrical data signal and the clock signal from the controller to drive the light emitting unit 11. As a result, the light emitting unit 11 outputs a normal optical signal S containing the data signal and the clock signal. This normal optical signal S is a high-output laser optical signal, and has a high risk of harm to human eyes.

The second drive circuit 13 includes first and second low-level light emission drive units 15 and 16 for driving the light-emitting unit 11 so that a low-level optical signal is emitted. , The function of stopping the operation of the first drive circuit 12.

The first low-level drive section 15 includes a light-emitting section 11
Is a low-power laser light signal that is harmless to human eyes (No. 1).
The light-emitting unit 1 outputs a low-level optical signal L1).
1 is to be driven. The first low-level optical signal L1 is formed of a sine wave or the like different from the normal optical signal S so that it can be distinguished from the normal optical signal S when received by the receiving unit 20 of the partner station. .

The second low-level driving section 16 is for driving the light-emitting section 11 so that the light-emitting section 11 outputs the second low-level optical signal L2. This second
Is also a low-power laser light signal which is harmless to human eyes. However, these light signals are distinguished from the normal light signal S and the first low-level light signal L1. And their frequencies are different.

The receiving section 20 receives a normal optical signal S, a first low-level optical signal L1, and a second low-level optical signal S1 inputted from a second optical fiber cable 60 for transmitting an optical signal from a partner station. The light receiving unit 21 converts the optical signal L2 of each level into an electric signal, amplifies and outputs the electric signal, and the electric signal converted from the normal optical signal S is input from the light receiving unit 21, and data is identified from among them. It has an identification circuit 22 that outputs each signal to a terminal (not shown), and a timing circuit 23 that determines the operation timing of the identification circuit 22 based on the extracted clock signal.

Numeral 30 filters the electric signal output from the light receiving section 21 and corresponds to the frequencies of the first and second low-level optical signals L1 and L2 among the electric signals input from the light receiving section 21. This is a filter that passes only frequencies.
As a result, the first and second low-level optical signals L1 and L2 are transmitted from the second optical fiber cable 60 to the light receiving unit 21.
Is detected.

The control section 40 has an input terminal X for inputting an electric signal indicating a normal optical signal S from the timing circuit 23, and the first and second low-level optical signals L passing through the filter 30.
1 and input terminals Y and Z for inputting electrical signals corresponding to L2. The control unit 40 controls the control signal C (C1, C2) to be output to the second drive circuit 13 of the transmission unit 10 based on the combination of the presence or absence of the electric signal input to these three input terminals X, Y, and Z. , C3).

FIG. 3 shows the operation of the control unit 40.
The case where there is a signal input at each of the input terminals X, Y and Z is indicated as “1”, and the case where there is no input is indicated as “0”.

When there is no input signal at any of the X, Y and Z input terminals of the control unit 40, that is, when there is no signal input to the light receiving unit 21, the control unit 40 sends the first signal from the light emitting unit 11 to the first terminal. A control signal C1 for outputting the low-level optical signal L1 and simultaneously stopping the first drive circuit 12 is output to the second drive circuit 13.

When there is a signal input at the Y input terminal of the control unit 40, that is, when the first low-level optical signal L1
Is input, the control unit 40 outputs a control signal C2 for outputting the second low-level optical signal L2 from the light emitting unit 11 and simultaneously stopping the first drive circuit 12 to the second drive circuit 13 Output to

When there is a signal input at the Z or X input terminal of the control unit 40, that is, when the second low-level optical signal L2 or the normal optical signal S is input to the light receiving unit 21, The unit 40 controls the first drive circuit 12 to operate to output the normal optical signal S from the light emitting unit 11 and at the same time, to prevent the two low-level optical signals L1 and L2 from being output. To the second drive circuit 13.

Next, the operation of this embodiment will be described.
FIG. 4 is an explanatory diagram of the operation when the second optical fiber cable 60 is disconnected. However, the filter 30 and the control unit 4
The illustration of 0 is omitted.

When the second optical fiber cable 60 is disconnected, no optical signal is input to the receiving unit 20a at the station A, so that the transmitting unit 10a transmits the normal optical signal S which is harmful to human eyes. The output is stopped, the first which is harmless to human eyes
The low-level optical signal L1 of the first optical fiber cable 5
Output to 0.

Then, in the station B, since the first low-level optical signal L1 is input to the receiving section 20b, the output of the normal optical signal S harmful to human eyes from the transmitting section 10b is stopped. Then, only the second low-level optical signal L2 harmless to human eyes is output to the disconnected second optical fiber cable 60.

When the disconnection state of the second optical fiber cable 60 is restored, the second low-level optical signal L2 output from the transmitting section 10b of the station B is transmitted to the receiving section 20 of the station A.
a, the control unit 40 of the station A transmits the signal to the transmitting unit 10a.
And outputs a control signal C3 to the second drive circuit 13. As a result, the first drive circuit 12 of the station A is in the operating state,
The light emitting unit 11 outputs a normal optical signal S, and the transmitting unit 1 of the station A
The output of the normal optical signal S at 0a is automatically restored.

When the receiving section 20b of the station B receives the ordinary optical signal S, the control section 40 of the station B also transmits
The control signal C3 is output to the second drive circuit 13 of Ob.
As a result, the first drive circuit 12 is also activated in the station B, the light emitting section 11 outputs the normal optical signal S, and the output of the normal optical signal S in the transmitting section 10b of the station B is also automatic. To recover.

FIG. 5 shows a case where both the first and second optical fiber cables 50 and 60 are disconnected.

In this case, the receiving units 2 of both the A and B stations
Since the first and second optical fiber cables 0a and 20b do not receive the optical signal at all, both the transmission units 10a and 10b both cut off the first low-level optical signal L1 harmless to human eyes. Output to 50 and 60.

When the second optical fiber cable 60 is restored, the receiving section 20a of the station A receives the first low-level optical signal L1 sent from the station B.
The transmitting unit 10a of the station A outputs the second low-level optical signal L2 to the disconnected first optical fiber cable 50.

Next, when the first optical fiber cable 50 is restored, the receiving section 20b of the station B receives the second low-level optical signal L2 sent from the station A, so that the transmitting section of the station B 10b outputs the normal optical signal S to the second optical fiber cable 60, and the optical output of the transmitting unit 10b of the station B is automatically restored first.

When the optical output from the transmitting section 10b of the station B is restored, the receiving section 20a of the station A receives the normal optical signal S. Therefore, the transmitting section 10a of the station A normally connects to the first optical fiber cable 50. And outputs the optical signal S of the
The light output is automatically restored.

FIG. 6 shows a second embodiment of the present invention. The present embodiment is an optical transmission apparatus in which the present invention is applied to bidirectional optical communication. Optical couplers 80a and 80b are provided at both stations A and B at both ends of an optical fiber cable 70, and these optical couplers 80a and 80b are provided. The transmitting units 10a and 10b and the receiving unit 20
a, 20b are optical fibers 55a, 55b, 65a, 6
5b.

Thus, the optical couplers 80a and 80b
The optical signals are output from the transmission units 10a and 10b of both stations to the optical fiber cable 70 via the
0 is transmitted to the receiving units 20a and 20b of the partner station.
To be received.

This embodiment is different from the first embodiment in that only the first low-level drive unit 15 operates in the second drive circuit 13 of the transmission unit 10.

In this embodiment, the optical fiber cable 7
If 0 is lost, the transmitting units 10a of both A and B stations,
10b outputs a first low-level optical signal L1 harmless to human eyes to the optical fiber cable 70.

When the optical fiber cable 70 is restored, both the receiving units 20a and 20b of the stations A and B receive the first low-level optical signal L1, so that the transmitting units 10a and 10a of the stations A and B receive the first low-level optical signal L1. At 10b, the light output is restored at the same time.

FIG. 7 shows a third embodiment of the present invention. 1
Reference numerals 00 and 101 denote first and second optical transmitters for converting an electric signal input from a terminal on the transmission side (not shown) into an optical signal and transmitting the optical signal. The electric signal is converted into an optical signal having a wavelength of, for example, 1.55 μm that does not cause harm to human eyes, and the second optical transmitter 101 converts the electric signal into an optical signal having a wavelength of 1.3 μm.

The output terminals of the two optical transmission units 100 and 101 are connected to a wavelength division multiplexing device 200 (200a), and the optical signals output from the two optical transmission units 100 and 101 are multiplexed by the wavelength division multiplexing device 200a. And output to the optical fiber cable 300.

The output end of the optical fiber cable 300 is connected to the wavelength division multiplexing device 200 (2
00b).

The wavelength division multiplexing device 200b separates the multiplexed optical signal transmitted through the optical fiber cable 300 into an optical signal having a wavelength of 1.55 μm and an optical signal having a wavelength of 1.3 μm. is there.

Reference numerals 110 and 111 denote wavelength division multiplexing devices.
The first and second receiving units convert the optical signals of wavelengths 1.55 μm and 1.3 μm separated by Ob into electric signals and output the electric signals to a terminal (not shown) on the receiving side.

Then, a detection circuit 120 and a control circuit 13 are provided between the first optical receiver 110 and the second optical transmitter 101.
0, the drive circuit 140 is connected in series.

The detection circuit 120 includes a first optical receiving unit 110
The detection signal indicating the presence or absence of the output of the
Output to Then, the control circuit 130 controls the detection circuit 12
When the detection signal input from “0” indicates “present” of the electric signal output of the first optical receiving unit 110, the driving circuit 140 activates the second optical transmitting unit 101, and the detection signal becomes the first optical receiving unit 110. When indicating "absence" of the electric signal output of the unit 110,
The driving circuit 140 stops the operation of the second optical transmission unit 101.

Therefore, when the optical fiber cable 300 is disconnected, the detection circuit 120 detects that no electric signal is output from the first optical receiver 110,
As a result, the control circuit 130 stops the operation of the second optical transmission unit 101 via the drive circuit 140, so that the wavelength 1.times. Only an optical signal of 55 μm is output, and an optical signal of a wavelength of 1.3 μm that is harmful to human eyes is not output.

Therefore, the optical connectors 301a, 301
Even if the connection b is disconnected, the retina of the eye is not damaged by an optical signal emitted from the optical fiber cable 300.

When the disconnected state of the optical fiber cable 300 is restored, an optical signal having a wavelength of 1.55 μm is input to the first optical receiving unit 110, and as a result, the control circuit 1
30 operates the second optical transmission unit 101 via the drive circuit 140, so that the optical signal having the wavelength of 1.55 μm and the wavelength 1.
Normal optical communication in which a 3 μm optical signal is multiplexed is automatically restored.

FIG. 8 shows a fourth embodiment of the present invention. The present embodiment is an optical transmission device in which the present invention is applied to bidirectional optical communication.
01 and the second receiving unit 111 are arranged in reverse, and the detecting circuit 120, the control circuit 130, and the driving circuit 140 are connected in series between them.

Other configurations and operations are the same as those of the third embodiment. Although two transmitting units and two receiving units are provided in the third and fourth embodiments, two or more transmitting units and two or more receiving units may be provided.

[0056]

According to the optical transmission apparatus of the present invention, when the optical fiber is cut off, the optical signal transmitting section does not cause harm to human eyes or a low-level optical signal. When only the optical signal of the wavelength is output, and when the disconnection state of the optical fiber is restored, there is an excellent effect that the normal optical signal output is automatically restored without performing the manual reset.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of the present invention.

FIG. 2 is a block diagram showing a first embodiment.

FIG. 3 is an explanatory diagram of an operation of a control unit according to the first embodiment.

FIG. 4 is an operation explanatory diagram of the first embodiment.

FIG. 5 is an operation explanatory diagram of the first embodiment.

FIG. 6 is a block diagram showing a second embodiment.

FIG. 7 is a block diagram showing a third embodiment.

FIG. 8 is a block diagram showing a fourth embodiment.

[Explanation of symbols]

 Reference Signs List 4 optical signal transmission control means 5 first optical fiber 6 second optical fiber 9 detecting means 10 optical signal transmitting unit 20 optical signal receiving unit

Continuation of the front page (56) References JP-A-55-6750 (JP, A) JP-A-2-10241 (JP, A) JP-A-62-6135 (JP, A) JP-A-53-130053 (JP) JP-A-2-162939 (JP, A) JP-A-60-178724 (JP, A) JP-A-57-111147 (JP, A) JP-A-4-324335 (JP, A) (58) Surveyed fields (Int. Cl. ⁶ , DB name) G01M 11/00-11/02 H04B 9/00

Claims (3)

(57) [Claims] 1. A light which can selectively output a normal optical signal and a low-level optical signal to a first optical fiber (5) for transmitting an optical signal to a partner station. A signal transmitting unit (10); an optical signal receiving unit (20) for receiving a plurality of types of optical signals input from a second optical fiber (6) for transmitting an optical signal from the partner station; Detecting means (9) for detecting the type of the optical signal received by the optical signal receiving section (20); and the first optical fiber (5) in response to a detection result of the detecting means (9). And an optical signal transmission control means (4) for controlling the operation of the optical signal transmission section (10) so as to switch the type of the optical signal output to the optical transmission apparatus. 2. The low-level optical signal comprises a first low-level optical signal and a second low-level optical signal. When the means (9) does not detect any of the normal optical signal and the first and second low-level optical signals, the optical signal transmitting unit (10) is transmitted to the first optical fiber (5). ) To output the first low-level optical signal. When the detection means (9) detects the first low-level optical signal, the optical signal is transmitted to the first optical fiber (5). The second low-level optical signal is output from the transmission unit (10), and when the detecting means (9) detects the second low-level optical signal or when the detecting means (9) detects the normal optical signal. When an optical signal is detected, the optical signal is transmitted to the first optical fiber (5). (10) from the optical transmission apparatus according to claim 1, wherein for outputting the normal optical signal. 3. A plurality of optical signal transmitting sections (100, 101) for outputting a plurality of optical signals having different wavelengths to an optical fiber (300), and a plurality of optical signal transmitting sections (100, 101) inputted from the optical fiber (300). A plurality of optical signal receiving sections (110, 111) for receiving one of the optical signals, and a plurality of optical signals received by the optical signal receiving sections (110, 111), which are most harmful to human eyes. Detecting means (120) for detecting the presence / absence of reception of an optical signal of a small specific wavelength; and light other than the optical signal of the specific wavelength when the detecting means (120) does not detect the reception of the optical signal of the specific wavelength. The output operation of the optical signal transmitting unit (101) for outputting a signal is stopped, and when the detection unit (120) detects reception of the optical signal of the specific wavelength, an optical signal other than the optical signal of the specific wavelength is output. Koshin The optical transmission apparatus characterized by comprising an optical signal transmission control means for causing the output operation to the transmitting unit (101) (130).