JPH0442643B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an improvement in an apparatus for fusion splicing optical fibers using heat generated by air discharge between discharge electrodes.

[Conventional technology]

When fusion splicing optical fibers, it is important to keep the applied heat constant because the melting state of the optical fibers differs depending on the heat. In devices that fusion splice optical fibers using the heat generated by air discharge between discharge electrodes, if the discharge power is kept constant, the heat applied to the optical fiber can be kept constant, making stable connections possible. However, conventionally, the current flowing between the discharge electrodes is detected and controlled so that this current is constant. That is, as shown in FIG. 4, after the DC voltage (for example, 12V) from a DC power source 1 such as a battery is lowered to about 10V by the dropper circuit 2,
Chopping with chopping circuit 3 to 20KHz~
It is converted into an alternating current of 100 KHz, boosted to several thousand volts by a booster circuit (for example, a transformer) 4, and sent to the discharge electrode 5 to cause an air discharge between them and generate heat. Then, the discharge current at this time is detected as a voltage generated across the resistor 51, and is fed back to the dropper circuit 2 to change the output voltage of the dropper circuit 2 so that the discharge current is constant. Such a conventional fusion splicing device has an advantage in that it can provide a stable discharge current even if the DC power source 1 is a battery or the like and is somewhat unstable.

[Problems to be solved by the invention]

However, the conventional constant current control method as described above has a problem in that the discharge power cannot be stabilized when the atmospheric pressure changes. Since the discharge power is expressed as the product of the voltage and current between the discharge electrodes, even if the discharge current is constant, unless the discharge voltage is constant, the discharge power will not be constant. The factors that change the voltage between the electrodes are:
There are changes in the electrode spacing and changes in atmospheric pressure, and the electrode spacing can be kept constant by using a special electrode rod, but changes in inter-electrode voltage due to atmospheric pressure cannot be dealt with with the constant current method described above. There is no. Changes in atmospheric pressure cannot be avoided because the connection work may be performed on a flat surface or at a high place such as a mountain top, or due to changes in the weather. When examining how the discharge power changes when the atmospheric pressure changes in a conventional fusion splicing device based on a constant current method, the results shown in FIG. 5 were obtained. As shown in this figure, as the atmospheric pressure decreases, the discharge power decreases, making it impossible to maintain optimal discharge fusion. To avoid this in conventional devices, the only way to avoid this is to change the set value of the discharge current each time there is a change in atmospheric pressure. SUMMARY OF THE INVENTION An object of the present invention is to provide a fusion splicing device that can automatically maintain a constant discharge power even when atmospheric pressure changes and can stably connect optical fibers.

[Means to solve the problem]

The optical fiber fusion splicing device according to the present invention includes:
A discharge electrode, a power supply device that applies a high voltage to the discharge electrode, a circuit that detects discharge current, a pressure sensor that detects atmospheric pressure, and controls the power supply device according to the detected discharge current and atmospheric pressure. and a feedback control circuit that changes the discharge current to keep the discharge power constant.

[Effect]

When detecting the discharge current and performing feedback control based on this to control the discharge current to a constant level, the pressure sensor detects the atmospheric pressure, and the detected atmospheric pressure is taken into account when controlling. The discharge current can be changed accordingly to keep the discharge power constant.

【Example】

In Fig. 1, a DC voltage (for example, 12V) from a DC power supply 1 is first lowered to about 10V by a dropper circuit 2, and then chopped by a chopper circuit 3 to convert it to AC of 20KHz to 100KHz, which is then boosted. The circuit (for example, a transformer) 4 boosts the voltage to several thousand volts, sends it to the discharge electrode 5, causes an air discharge between them, and generates heat, and the discharge current at this time is the voltage generated across the resistor 51. detected as,
The configuration of feeding back to the dropper circuit 2 and changing the output voltage of the dropper circuit 2 is the fourth configuration.
Same as the figure. Here, a pressure sensor 6 is further provided, and the detected atmospheric pressure is detected by the pressure sensor 6.
CPU (microprocessor) via D converter 7
8, and a reference voltage switching circuit 9 is configured to be switched by the output of the CPU 8. This reference voltage is sent to the dropper circuit 2 to be compared with the voltage taken out from one end of the resistor 51 (corresponding to the discharge current). This dropper circuit 2 is shown here in principle for easy understanding.
It has a series transistor 21 and an error amplifier 22, and the error amplifier 22 compares the voltage taken out from one end of the resistor 51 with a reference voltage, and gives the output of the difference to the base of the transistor 21 to reduce the voltage drop. Control. The reference voltage switching circuit 9 includes a resistive voltage dividing circuit 91 and a relay 92, and switches the voltage dividing ratio by turning on and off each contact 93 of the relay 92. That is, a constant voltage obtained from the Zener diode 23 is applied to one end of the resistive voltage divider circuit 91, and this constant voltage is divided by the resistive voltage divider circuit 91 and applied to the positive side of the error amplifier 22 as a reference voltage. Given. The relay 92 is operated according to the atmospheric pressure detected by the pressure sensor 6, and the error amplifier 22
The reference voltage to be sent to is switched. As a result, the voltage drop is controlled and the discharge current is changed in accordance with the amount of change in the discharge voltage that changes in accordance with the change in atmospheric pressure. In this example, control is performed so that a discharge current P (mA) determined by the formula P = b + 0.018 (1013 - x) is obtained when the atmospheric pressure is x (millibar) from the relationship between the atmospheric pressure and the discharge power shown in Fig. 5. has been done. Note that b is the standard value of the discharge current depending on the type of optical fiber to be connected, and here it is
Although it was set to 16mA, if it could be set using a deep switch, etc., the operator could change it each time depending on the type of optical fiber. With such a configuration, the discharge current was controlled according to the atmospheric pressure, and when the discharge current and discharge power were measured with respect to changes in the atmospheric pressure, the results shown in FIG. 2 were obtained. From this figure 2, it can be seen that the discharge current is very well controlled so that the discharge power is constant, and that the optical fiber can be stably connected with stable discharge power even during connection work at high places. . FIG. 3 shows another embodiment, in which the voltage at one end of the resistor 51 and the voltage output from the pressure sensor 6 are multiplied by a multiplier circuit 10 and then fed back to the error amplifier 22 of the dropper circuit 2. In this case, if the atmospheric pressure decreases, the output voltage of the pressure sensor 6 decreases accordingly, so the amount of feedback decreases, the output voltage of the dropper circuit 2 increases, and the discharge current increases, resulting in a constant discharge current. The discharge power will be . This embodiment has the advantage that fewer additional parts are required compared to the embodiment of FIG.

【Effect of the invention】

According to the optical fiber fusion splicing device of this invention,
The pressure sensor detects the atmospheric pressure, and the discharge current is controlled by taking this detected atmospheric pressure into account.
It is possible to automatically keep the discharge power constant even if there is a change in atmospheric pressure. Therefore, optical fibers can always be connected stably even when the weather changes or when working at heights.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is a graph showing the measurement results of control characteristics in this embodiment, and FIG. 3 is a block diagram of another embodiment.
FIG. 4 is a block diagram of the conventional example, and FIG. 5 is a graph showing the measurement results of discharge power with respect to changes in atmospheric pressure in the example of FIG. 1...DC power supply, 2...Dropper circuit, 3...
Chopper circuit, 4... Boost circuit, 5... Discharge electrode, 6... Pressure sensor, 7... A/D changer,
8...CPU, 9...Reference voltage switching circuit, 10...
...multiplication circuit.

Claims (1)

[Claims] 1. A discharge electrode, a power supply device that applies a high voltage to the discharge electrode, a circuit that detects discharge current, a pressure sensor that detects atmospheric pressure, and controls the power supply device according to the detected discharge current and atmospheric pressure. 1. An optical fiber fusion splicing device having a feedback control circuit which thereby changes the discharge current and makes the discharge power constant.