JPH07140001A - Optical power measuring apparatus - Google Patents

Abstract

PURPOSE:To accurately detect the breaking or contact failure of a wire in the wiring of a photodiode and to provide an optical power measuring apparatus capable of always obtaining accurate measurement data. CONSTITUTION:The device comprises an average value-measuring circuit 6 that measures 8F} average value of current signals supplied from a diode PD and outputs the voltage signal in accordance with the measured average value and a comparator circuit 7 that compares the voltage signal outputted from the circuit 6 with a reference voltage which is smaller than a voltage corresponding to a dark current of the diode PD and outputs a comparing signal having a sign corresponding to the compared result. When the sign of the comparing signal is inverted, information indicating the occurrence of an abnormality is transmitted to an operator and the measurement data are canceled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical power measuring device suitable for use in, for example, a fiber-correlation device and an optical power meter.

[0002]

2. Description of the Related Art Generally, an optical power measuring device used for a core wire checking device, an optical power meter or the like has a photodiode (hereinafter referred to as a diode PD), and supplies the light to be measured to the diode PD. Measure the power of the measured light. A conventional optical power measuring device will be described with reference to the drawings. FIG. 4 is a diagram showing an example of the configuration of a general optical power measuring device, in which the configuration around the diode PD is shown enlarged.

In FIG. 4, reference numeral 1 denotes, for example, a trans-impedance type amplifier, which converts a current signal generated in the diode PD by the measured light into a corresponding voltage signal. The amplifier 1 has a range switching function and the like. The current signal generated in the diode PD is converted into a voltage signal in the amplifier 1 and then subjected to processing such as amplification and A / D conversion, and finally used as optical power measurement data of the light under measurement.

As a conventional optical power measuring device, as shown in FIG. 5, a main body 2 having an amplifier, a detecting circuit 5 and the like and a sensor portion 3 having a diode PD are bendable as shown in FIG. Some are connected by a connecting cord 4. In general, the connection cord 4 is composed of a plurality of copper wires, one or more of which is connected to the detection circuit 5 in the main body 2 so that the sensor unit 3 and the connection cord 4 can be securely connected to the main body 2. Whether or not it is connected 1
It is used to judge whether or not there is a problem such as disconnection or poor contact in a book or a plurality of copper wires.

[0005]

By the way, in the optical power measuring apparatus having the configuration shown in FIG. 4, as shown in FIG.
When the signal line connecting the diode PD and the amplifier 1 is disconnected, the current signal from the diode PD does not reach the amplifier 1. However, since the input of the amplifier 1 has a high impedance, the amplifier 1 is easily affected by external noise and may operate as if a current signal was supplied from the diode PD.

In such a case, the circuit following the amplifier 1 cannot determine that the voltage signal output from the amplifier 1 is due to noise. Therefore, the optical power measuring device displays or outputs meaningless measurement data. However, since the measured or displayed measurement data is a specific numerical value, the operator mistakenly recognizes the obtained measurement data as accurate measurement data and performs a corresponding process. Therefore, when the optical power measuring device having the configuration shown in FIG. 4 is applied to the optical fiber contrast device used for extracting the optical fiber optical fiber to be cut, there is a risk of causing a serious accident such as erroneous cutting of the optical fiber. There is a nature.

Further, in the optical power measuring device having the structure shown in FIG. 5, the main body 2 and the sensor portion 3 are connected by the connecting cord 4, and the connecting cord 4 is bent as necessary, so that the inside of the connecting cord 4 is The copper wire is likely to be cut. further,
The connection cord 4 has a structure in which a connector portion is formed at its tip (one end or both ends), and the connector portion is connected to the main body 2 and the sensor portion 3 in many cases. In this case, contact failure and disconnection often occur in the connector portion.

When such disconnection or contact failure occurs, as described above, there is a risk of erroneously recognizing the measurement data due to noise as accurate measurement data. In addition, the detection circuit 5
If a copper wire (copper wire connected to the diode PD) other than the one or a plurality of copper wires connected to the wire breaks or a contact failure occurs, there is a drawback that it cannot be detected.

In order to prevent such various inconveniences, an operation confirmation work is performed before the measurement work (for example, a test light is incident on the optical power measuring device to confirm whether or not the measured data has a prescribed value). There are also operational approaches such as However, for example, when a copper wire or a signal wire has a poor contact, there is a case where the copper wire or the signal wire operates normally at the time of checking the operation and becomes disconnected at the time of work, which is not a sufficient countermeasure.

Further, since the operation confirmation work requires a tool and time for the work, there is a problem that the overall work efficiency is lowered. Therefore, when a disconnection or a contact failure occurs in the wiring of the diode PD, an apparatus that can immediately detect the disconnection or the erroneous processing due to meaningless measurement data is desired. ing. The present invention has been made in view of the above circumstances, and provides an optical power measurement device that can accurately detect disconnection or contact failure in the wiring of a photodiode and can always obtain accurate measurement data. The purpose is to

[0011]

An optical power measuring apparatus according to the present invention comprises a photodiode for outputting a current signal corresponding to incident light to be measured, and the light to be measured by subjecting the current signal to predetermined processing. In the optical power measuring device having a measuring means for outputting measurement data according to, the average value measuring means for measuring the average value of the current signal, and the average value measured by the average value measuring means, the photodiode Comparing means for comparing with a reference value smaller than the dark current, and transmitting means for transmitting information according to the comparison result by the comparing means to the operator or the measuring means.

[0012]

According to the optical power measuring device having the above structure, the average value measuring means measures the average value of the current signal output from the photodiode, and the comparing means calculates the average value from the dark current of the photodiode. Compare with a smaller reference value. Then, the transmission unit transmits information according to the comparison result of the comparison unit to the operator or the measurement unit. In this way, disconnection or defective contact in the wiring of the photodiode can be accurately detected. Moreover, since the above-described processing is performed in parallel with the measurement processing by the measuring device, the operator or the measuring device can immediately recognize the occurrence of the disconnection or the contact failure. That is, the measurement data output from the optical power measuring device is always an accurate value.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention utilizes the property that "the diode PD outputs a dark current including a predetermined direct current even if the light to be measured is not incident". An embodiment of the present invention will be described. 1 is a block diagram showing a partial configuration of an optical power measuring apparatus according to a first embodiment of the present invention. In this figure, parts corresponding to the respective parts in FIG. Omit it.

In the figure, 6 is an average value measuring circuit for measuring the average current value of the current signal supplied via the signal line 6a, and outputs a voltage signal according to the average current value.
Specifically, when the measured light is not incident on the diode PD, a voltage signal corresponding to the average current value of the dark current output from the diode PD itself is output and the measured light is incident on the diode PD. In that case, a voltage signal corresponding to the average current value (greater than the average current value of the dark current) of the current signal supplied corresponding to the measured light is output.

Further, the average value measuring circuit 6 outputs a voltage signal of "zero" when the current signal is not supplied from the signal line 6a due to some inconvenience. Here, a configuration example of the average value measuring circuit 6 is shown in FIG. In this figure, 8 is a trans-impedance amplifier, 9 is a resistor having a resistance value R, and 10 is a capacitor having an electrostatic capacitance C. In the average value measuring circuit 6 shown in this figure, the capacitor 10
If the electrostatic capacitance C is set to a large value, a more stable average value output can be obtained, but the reaction speed decreases.

The capacitance C and the resistance value R are set according to the device to which the device 6 is applied. In addition, the diode PD
In some cases, the dark current may be extremely small, so
An amplifier and a low-pass filter (not shown) are added if necessary. As shown in this figure, since the average value measuring circuit 6 is simply configured, the above-mentioned various settings and additional work can be easily performed.

Referring again to FIG. 1, reference numeral 7 is a comparison circuit for comparing the voltage signal output from the average value measuring circuit with a preset reference voltage (reference value). Output a signal. If the comparison result is similar to the immediately preceding comparison result, this comparison signal is the same, and if they are different, the sign of the immediately preceding comparison signal is inverted. Further, the magnitude of the reference voltage is set to be smaller than the voltage signal according to the dark current and larger than “zero”.

Further, although not shown, various devices (for example, for transmitting the operating state (normal or abnormal) of the optical power measuring device to the operator in accordance with the change of the comparison signal are provided at the subsequent stage of the comparison circuit 7. , Alarm) and circuits for invalidating the current measurement data. Although not shown,
In the subsequent stage of the amplifier 1, various circuits that perform processing such as amplification and A / D conversion on the voltage signal output from the amplifier 1 are provided.

In such a structure, first, normal operation (operation when disconnection, contact failure, etc. have not occurred) will be described. First, when the measured light is not incident on the diode PD, a dark current is supplied to the amplifier 1 and the average value measuring circuit 6. Therefore, a voltage signal according to the average current value of the dark current is supplied from the average value measuring circuit 6 to the comparison circuit 7. Since the magnitude of this voltage signal is larger than the reference voltage, the relationship “voltage signal”> “reference signal” is established, and the comparison circuit 7 outputs a comparison signal according to this relationship.

Since the comparison signal thus output is the same as the comparison signal output immediately before, the various devices in the subsequent stage inform the operator that the optical power measuring device is operating normally. Further, the dark current can be converted into a voltage signal in the amplifier 1, subjected to processing such as amplification and A / D conversion, and finally used as the optical power measurement data of the measured light.

In such a state, the diode PD
When the light to be measured is incident on, a current signal (current value is larger than dark current) corresponding to the light to be measured is supplied to the amplifier 1 and the average value measuring circuit 6. Therefore, the average value measurement circuit 6 supplies the voltage signal corresponding to the average current value of the current signal to the comparison circuit 7. Since the voltage value of this voltage signal is greater than or equal to the reference voltage, the relationship “voltage signal”> “reference signal” is established, and the comparison circuit 7 outputs a comparison signal corresponding to this relationship. Since the subsequent operation is the same as the above-mentioned case, its explanation is omitted.

Next, the operation at the time of occurrence of an abnormality such as disconnection or contact failure will be described. When the signal line connecting the diode PD and the amplifier 1 is disconnected, noise is mixed from the outside and is supplied to the average value measuring circuit 6. This noise is an AC component of a signal in which a signal group of a predetermined frequency (normally 50 to 60 [Hz]) is AC-coupled, and the average current value obtained by the average value measuring circuit 6 is “zero”.
Therefore, the voltage value of the voltage signal output from the average value measurement circuit 6 is always “zero”, the relationship “voltage signal” <“reference voltage” is established, and the comparison signal output from the comparison circuit 7 is inverted. It

As described above, the comparison signal does not match the comparison signal output immediately before.
The operator is informed that the optical power measuring device is malfunctioning. Further, the optical power measurement data supplied via the amplifier 1 or the like is hidden or invalidated by various circuits subsequent to the comparison circuit 7. As a result, the operator can accurately recognize the occurrence of the abnormality and take appropriate measures.

As described above, according to the first embodiment of the present invention, since the dark current of the diode PD is used, the failure of the diode PD and the disconnection of the signal line of the diode PD can be accurately detected. it can. Further, since the disconnection is always detected in parallel with the measurement operation, it is possible to determine whether or not the measured data has a normal value even if a contact failure that causes an unstable operation occurs.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a diagram showing a partial configuration of an optical power measuring device according to a second embodiment of the present invention. In this figure, parts corresponding to those in FIG. Omit it. In FIG. 3, SW is a switch inserted in a signal line connecting the diode PD and the amplifier 1, and a contact point 11 provided on the amplifier 1 side.
And a contact 12 provided at one end of a resistor 13 (described later). The switch SW is normally in contact with the contact 11, and is switched to the contact 12 side for a predetermined time when the detection switch (not shown) is pressed by the operator.

The resistor 13 has a predetermined resistance value, and a sufficiently large negative voltage Vss is applied to the other end. Although not shown, a voltmeter is connected in parallel with the resistor 13 to measure the voltage drop Vpd in the resistor 13. Then, following this voltmeter, an A / D converter that converts the voltage drop Vpd into digital data, a comparator that compares the output of the A / D converter with a preset value, and a comparison by this comparator Various devices and the like for performing processing according to the result are provided.

In the above comparator, the "preset value" is smaller than the voltage drop Vpd and is larger than "zero" in the normal operation, so that the kind and the resistance of the diode PD to be used are set. It is determined according to the resistance value of 13. Further, in the subsequent stage of the amplifier 1, various circuits that perform processing such as amplification and A / D conversion on the voltage signal output from the amplifier 1 as in the optical power measuring apparatus according to the first embodiment described above. Is provided.

In such a structure, the measuring operation will be described first. The switch SW first contacts the contact 11, and the current signal output from the diode PD is supplied to the amplifier 1. Here, if the signal line connecting the diode PD and the switch SW is broken, noise is mixed from the outside, and this noise is converted into a current signal by the amplifier 1.
Is supplied to. The subsequent steps until obtaining the optical power measurement data are the same as those in the above-described first embodiment, and the description thereof will be omitted.

By the way, when detecting the presence or absence of disconnection,
The detection switch is pressed by the operator, and the switch SW is switched to the contact 12 side. Since the negative voltage Vss is applied to the other end of the resistor 13, a forward current flows from the diode PD to the resistor 13 when the signal line between the diode PD and the switch SW is not broken. The voltage drop Vpd in the resistor 13 at this time is measured by a voltmeter, A / D converted, and then compared with a preset value in a comparison circuit.

If no abnormality such as disconnection has occurred, "voltage drop Vpd">"presetvalue", and a message or the like indicating that the above-described measurement operation is normally transmitted to the operator. To be done. Then, the switch SW returns to the contact 11 side, and the measurement operation is continuously performed. On the other hand, when a disconnection occurs in the signal line connecting the diode PD and the switch 1, even if the switch SW contacts the contact 12, no current flows from the resistor 13 to the diode PD. Therefore, the voltage drop Vpd becomes “zero”. That is, “voltage drop Vpd” <“preset value”, a message or alarm indicating an abnormal operation is transmitted to the operator, and the switch S is pressed until the abnormality such as disconnection is repaired.
The measurement operation is stopped by keeping W in contact with the contact 12.

As described above, in the second embodiment of the present invention, it is possible to reliably detect the failure of the diode PD and the disconnection of the signal line of the diode PD. Further, even during the measurement operation, the operator can detect the connection state of the diode PD by pressing the detection button. This detection work is performed at the actual work site immediately after the optical power measuring device is installed and the predetermined settings are made.
That is, when done just before the measurement, it is possible to prevent a phenomenon such as "because of poor contact, normal operation occurs during operation confirmation but abnormal operation occurs during actual measurement work".

In the second embodiment described above, the resistor 1
Although the negative voltage Vss is applied to 3, the polarity of the diode PD may be reversed and a positive voltage may be applied to the resistor 13. Instead of the resistor 13 and the negative voltage Vss, a current source may be used and the current value output from this current source may be directly measured. At this time, in the comparator, the measured current value is compared with the “preset value”.

[0033]

As described above, according to the present invention,
The average value measuring means measures an average value of the current signal output from the photodiode, and the comparing means compares the average value with a reference value smaller than the dark current of the photodiode. Then, the transmission unit transmits information according to the comparison result of the comparison unit to the operator or the measurement unit. Therefore, there is an effect that it is possible to accurately detect disconnection or contact failure in the wiring of the photodiode.
Moreover, since the above-described processing is performed in parallel with the measurement processing by the measuring device, the operator or the measuring device can immediately recognize the occurrence of the disconnection or the contact failure. Therefore, there is an effect that the measurement data output from the optical power measuring device can always be an accurate value.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an optical power measuring device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a configuration example of an average value measuring circuit 6.

FIG. 3 is a block diagram showing a schematic configuration of an optical power measuring device according to a second embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration example of a conventional optical power measuring device.

FIG. 5 is a block diagram showing a configuration example of a conventional optical power measuring device.

FIG. 6 is a block diagram for explaining a problem of a conventional optical power measuring device.

[Explanation of symbols]

1 ... Amplifier, 6 ... Average value measuring circuit, 7 ... Comparison circuit, 11,12 ... Contact, 13 ... Resistance, PD ... Photodiode, SW ... Switch, Vpd ... Voltage drop, Vss ... … Negative voltage

Claims (2)

[Claims] 1. A photodiode which outputs a current signal corresponding to the incident light to be measured, and a measuring means which performs predetermined processing on the current signal and outputs measurement data corresponding to the light to be measured. In the optical power measuring device, average value measuring means for measuring the average value of the current signal, and comparing means for comparing the average value measured by the average value measuring means with a reference value smaller than the dark current of the photodiode. And a transmission means for transmitting information according to a comparison result by the comparison means to an operator or the measurement means. 2. A photodiode which outputs a current signal according to the incident measured light, and a measuring means which performs a predetermined process on the current signal and outputs measured data corresponding to the measured light. In the optical power measuring device, there is provided switching means inserted between the photodiode and the measuring means, and a circuit provided in parallel with the measuring means, wherein the photodiode has a value corresponding to a current flowing in the circuit. Comprising a value according to the characteristics of the, and the detection means for transmitting information according to the comparison result to the operator or the measuring means, the switching means, by switching the measuring means or the measuring circuit An optical power measuring device connected to the photodiode.