JP2529451B2 - Optical communication unit - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical communication unit used by connecting to an optical network.

2. Description of the Related Art A conventional communication unit of this type, as shown in FIG. 3, converts an electrical signal into an optical signal and an optical switch 3 that optically and removably intervenes in a transmission trunk line 2 of a ring-shaped optical network 1. And a light receiving unit 5 for converting an optical signal into an electric signal, and a reception level detecting section 6 for detecting the level of the electric signal converted by the light receiving unit 5, and when there is no transmission data, A relay that converts an optical signal introduced from the transmission trunk line 2 through the optical switch 3 into an electric signal in the light receiving unit 5 and then converts the electric signal into an optical signal in the light emitting unit 4 and retransmits it to the transmission trunk line 2. If there is transmission data, the relay operation is stopped, the transmission data is converted into an optical signal and output to the transmission trunk line 2, and the reception operation is performed due to a failure of equipment or the like. When the bell detection unit 6 detects a reception level lower than the normal level, the issuing operation of the light emitting unit 4 is stopped, and the optical switch 3 is controlled to optically move the light emitting unit 4 and the light receiving unit 5 from the optical network 2. Was dismissed (for example, JP-A-55
−73152).

However, according to such a configuration, when a failure of a device, in particular, a light output of a light emitting unit is reduced, defective data circulates in the optical network, and another device or system on the optical network. There is a problem that there is a great risk of adversely affecting the.

 The above problem occurs for the following reasons.

That is, firstly, the light output of the light emitting unit is reduced due to long-term use or aging. When this optical output falls below a specified level, defective data is generated due to insufficient power, and this defective data is sent to the optical network.

Secondly, even if the self-transmitted data is bad, this is detected because the self-transmitted data is received in one round in the optical network and further converted into an electric signal by the own light-receiving unit. Since then. Based on this detection, even if the light emitting operation of the light emitting unit is stopped and the light switch is controlled to optically disconnect the light emitting unit from the optical network, at this stage,
It was too late to prevent the bad data from circling sufficiently in the optical network and preventing the other devices or systems on the optical network from being adversely affected.

The present invention has been made in view of the above problems, and when defective data occurs, the transmission of the defective data is stopped early to reduce the influence on other devices or systems on the optical network. It is an object of the present invention to provide an optical communication unit that can be used.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention branches an optical signal of a light emitting unit that converts an electric signal into an optical signal before sending it to an optical network. The power level is detected, and when the detected power level becomes lower than a predetermined level, the light emitting operation of the light emitting unit is stopped and the light emitting unit is optically separated from the optical network. It is a thing.

Effect of the Invention With the above-described configuration, according to the present invention, the presence or absence of a defect in data sent from the light emitting unit is detected without waiting for the data sent from the device to be received after it has gone through the optical network. When defective data occurs due to insufficient power of the light emitting unit because it is stopped and disconnected from the optical network, the transmission of this defective data is stopped early and the influence on other devices or systems on the optical network is affected. Can be reduced.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

It should be noted that the same or corresponding parts as in the conventional case are denoted by the same reference numerals. FIG. 1 shows a schematic configuration of an optical communication unit according to an embodiment of the present invention. Reference numeral 1 is a ring-shaped optical network configured by using an optical fiber for a transmission trunk 2, and 3 is the optical network 1. An optical switch for optically detachably intervening in the transmission trunk line, 4 is a light emitting unit for converting an electric signal into an optical signal, 5 is a light receiving unit for converting an optical signal into an electric signal, and 7 is an optical signal of the light emitting unit 4. Is an optical branching device for branching the optical signal before sending it to the transmission trunk line 2, and an optical level detector 8 for detecting whether or not the power level of the optical signal branched by the optical branching device 7 is below a predetermined level. .

Here, the optical switch 3 is controlled on the basis of the detection output of the optical level detecting section 8, and in a normal state in which the optical level detecting section 8 detects an optical signal of a predetermined level, the light emitting unit 4 and the light receiving unit 5 are provided on the transmission trunk line 2. The optical signal received from the transmission trunk line 2 is introduced into the light receiving unit 5 and the optical signal output from the light emitting unit 4 is led out to the transmission trunk line 2 by optically intervening. On the other hand, when the light level detection unit 8 detects an optical signal of a predetermined level or less, the light emitting unit 4 and the light receiving unit 5 are optically separated from the transmission trunk line 2 and an optical bypass path is formed on the transmission trunk line 2. The optical signal in the optical network 1 is configured to pass without passing through the light emitting unit 4 and the light receiving unit 5.

The light level detection unit 8 gives the detected output to the optical switch 3 as a switching control signal and to the light emitting unit 4 as a light emission stop signal to emit light when an abnormality occurs when an optical signal below a predetermined level is detected. The unit 4 and the light receiving unit 5 are optically separated from the transmission main line 2, and the light emitting operation of the light emitting unit 4 is stopped.

The operation of the optical communication unit configured as described above will be described below.

First, regarding normal operation of the optical communication unit described above, when there is no transmission data, after the optical signal introduced from the transmission trunk line 2 through the optical switch 3 is once converted into an electric signal by the light receiving unit 5, A relay operation is performed in which the electric signal is converted into an optical signal by the light emitting unit 4 and sent to the transmission trunk line 2. On the other hand, if there is transmission data, the relay operation is stopped, the transmission data is converted into an optical signal, and the optical signal is transmitted to the transmission trunk line 2.

Here, the power level of the optical signal sent from the light emitting unit 4 to the transmission trunk line 2 becomes lower than a predetermined level due to long-term use or aging of a light emitting element such as a semiconductor laser or a light emitting diode, and thus defective data is recorded. When there is a risk of sending out, this state is detected by the light level detection unit 8. The detection unit 8 that has detected the decrease in the power level of the optical signal is
The light emitting operation of the light emitting unit 4 is stopped and the light switch 3 is controlled to optically separate the light emitting unit 4 and the light receiving unit 5 from the transmission trunk line 2. This allows
An avoidance operation is performed to prevent defective data from being sent to the optical network 1.

At this time, it should be noted that the avoidance operation is performed immediately when the light emitting unit 4 issues the defective data, without waiting for the defective data to be received through the optical network 1 once. Is. Thus, when defective data is generated due to insufficient power of the light emitting unit 4, the transmission of the defective data is stopped early to minimize the influence on other devices or the system on the optical network 1. Will be able to.

The detection output of the level detection unit 8 can also be used as a signal indicating whether the output of its own optical signal is normal or abnormal. For example, by driving the display means such as the sound alarm or the alarm lamp by the above detection output, it becomes possible to promptly inform the user of the occurrence of the abnormality.

FIG. 2 shows an example of the configuration of the optical level detecting section 8 suitable for the optical communication unit of the present invention, which comprises a light receiving section 81, a sample and hold circuit 82, a level comparing circuit 83 and the like.

The light receiving unit 81 photoelectrically converts the optical branch output from the light emitting unit 4. The sample and hold circuit 82 samples the converted output level of the light receiving unit 81 in synchronization with the electric signal input to the light emitting unit 4 for transmission. The level comparison circuit 83 uses the sample and hold circuit 82.
The converted output level sampled by is compared with a predetermined reference level Vs, and the comparison result is output as a light level detection output.

The above-mentioned optical level detecting section 8 can detect the power level of the optical signal only at the peak level, that is, the level at the logic "1". As a result, it is possible to instantly detect a decrease in the optical output level of the light emitting unit 4, so that the timing of stopping the transmission of defective data due to insufficient optical power is further advanced, and other devices or systems on the optical network 1 can be detected. It is possible to further reduce the influence. When a semiconductor laser is used for the light emitting element of the light emitting unit 4, the light receiving section 81 of the light level detecting section 8 may use a monitor light receiving section for feedback controlling the light emission of the semiconductor laser.

As is apparent from the above description, according to the present invention, an optical signal of a light emitting unit that converts an electric signal into an optical signal is branched before being sent to an optical network, and the power level of the branched optical signal is changed. When the detected power level falls below a predetermined level, the light emitting operation of the light emitting unit is stopped, and the light emitting unit is optically separated from the optical network, so that its own transmission data is transmitted. Insufficient power is supplied to the light emitting unit because the presence or absence of defective data is detected without waiting for the data to be looped through the network, and the light emitting unit is stopped from emitting light and removed from the optical network based on this detection. When defective data is generated due to the above, the transmission of this defective data is stopped early so that another device on the optical network can operate. It has the effect that the influence on the system can be reduced. Furthermore, since the sample-and-hold means extracts the optical signal in response to the synchronization signal from the electric signal, it is possible to detect a gradual change in the light-emitting element over time, and further, for each bit. It is possible to prevent the output of faulty data on the network at an early stage by detecting the instantaneous level change of.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an optical communication unit according to an embodiment of the present invention, FIG. 2 is a block diagram showing a configuration example of an optical level detection unit suitable for the unit, and FIG. 3 is a conventional optical communication unit. It is a schematic block diagram. 1 ... Ring-shaped optical network, 2 ... Optical network 1
Transmission trunk line, 3 ... Optical switch, 4 ... Light emitting unit, 5 ...
Light receiving unit, 7 ... Optical branching device, 8 ... Optical level detector,
81 ... Light receiving part of light level detecting part, 82 ... Sample and hold circuit, 83 ... Level comparing circuit.

Claims (1)

(57) [Claims] 1. A light emitting unit for converting an electric signal into an optical signal, an optical switch for optically interleaving the light emitting unit in an optical network, and before transmitting the optical signal of the light emitting unit to the optical network. An optical branching device for branching to, a sample hold means for detecting an optical signal branched by the branching device in response to a synchronizing signal from the electric signal, and a power level of the optical signal obtained by the sample hold means Optical communication provided with an optical level detector for stopping the light emitting operation of the light emitting unit and controlling the optical switch to optically disconnect the light emitting unit from the optical network when the level becomes lower than a predetermined level. unit.