JP3403286B2 - Discharge control method for optical fiber fusion splicer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge control method for an optical fiber fusion splicer. 2. Description of the Related Art In an optical fiber fusion splicer, the amount of heat generated in the aerial discharge for melting the end face of an optical fiber is as follows.
It changes depending on the state of the air as the heating resistor. Therefore, it is necessary to correct the discharge conditions depending on the state of the air in order to obtain the optimal discharge heat generation. For this reason, a discharge control method as shown in FIG. 7 has conventionally been employed. In FIG. 7, 11 is an optical fiber to be fusion-spliced, 13 is a discharge electrode, and 15 is a power supply for discharge. In this method, the discharge power supply 15 is controlled as follows in order to obtain an optimal discharge heat value. First, various parameters representing the state of air, such as atmospheric pressure, temperature, and humidity, are measured by sensors 17a, 17b, and 17c.
... Next, a correlation coefficient calculator 19 calculates a correlation coefficient between the change in each parameter and the change in the amount of heat generated by discharge. The arithmetic unit 19 incorporates conditional expressions obtained in advance by experiments. Next, a correction value is calculated by the calculator 23 from the correlation coefficient and the target value 21, and the correction value is added to the previous discharge condition by the adder 25, so that the discharge heat amount for the next discharge is optimized. The discharge condition of the power supply 15 is determined. Conventionally, control has been performed in such a manner as to optimize the amount of heat generated by discharge. As the discharge power supply 15, an inverter having a high frequency (several tens of kHz to several hundreds of kHz) output is used for the purpose of stabilizing a discharge phenomenon. Therefore, for example, when a discharge ON command as shown in FIG. 8A is input to the discharge power supply 15, a discharge current as shown in FIG. The discharge intensity that affects the amount of heat generated can be controlled by adjusting the discharge pulse width (duty ratio) during one cycle of the discharge current. [0006] The conventional discharge control method employs means for detecting the state of air and correcting the discharge condition based on the detected air state. Therefore, a large number of sensors are required to detect the air condition. Further, since the amount of heat generated by discharge also changes due to deterioration of the electrode and the attachment of foreign matter to the electrode, it is not possible to cope with a change in the amount of heat generated by discharge due to factors other than air only by detecting the state of air. Further, when the surface state of the discharge electrode 13 is bad or when the correction amount is insufficient, the discharge ON as shown in FIG.
However, even if the command is input, the discharge may be interrupted as shown in FIG. With the conventional control method, it is not possible to accurately grasp such a break in the discharge. A first object of the present invention is to provide an optical fiber fusion splicer which does not require a large number of sensors and which can appropriately control the amount of heat generated by discharge in response to changes in all parameters affecting discharge. It is to provide a discharge control method. It is a second object of the present invention to detect when a discharge is interrupted beyond a permissible limit within a time for which the discharge is to be continued, and to issue an alarm. In order to achieve the first object, a discharge control method according to the present invention detects a discharge waveform between discharge electrodes by a sensor, and detects a discharge pulse width and a discharge pulse width from the detected discharge waveform. The present invention is characterized in that a discharge duration time is obtained and compared with a target value to control a discharge pulse width and a discharge time. The influence of all parameters such as air condition and electrode surface condition appears on the discharge waveform, so if this discharge waveform is detected and the discharge pulse width and discharge duration are controlled based on it, the effect on the discharge will be affected. Appropriate discharge control can be performed in accordance with all of the applied parameter changes. As a sensor for detecting a discharge waveform, a photodiode, a phototransistor, a photo IC, which directly observes an arc between the electrodes and converts the arc into an electric signal.
An optical sensor such as a CCD line sensor, a CCD area sensor, or a TV camera, or a current waveform detector that detects a discharge current waveform flowing between the electrodes on a conductor between the power supply and the electrodes can be used. In order to achieve the second object,
In the discharge control method of the present invention as described above, the interruption of the discharge within the time to sustain the discharge is detected from the detected discharge waveform, and the interruption of the discharge is longer than a predetermined time or the interruption of the discharge repeatedly occurs. If so, an alarm may be issued. [Embodiment 1] FIG. 1 shows an embodiment of a discharge control method according to the present invention. In the figure, 11 is an optical fiber, 13 is a discharge electrode, and 15 is a power supply for discharge. The discharge power supply 15 is the same as the conventional one, and the output of the DC power supply 27 is converted by an inverter 29 into an AC of several tens of kHz to several hundreds of kHz to form
13 to generate a discharge. The magnitude (average value) of the discharge current is detected by a current detector 31. Reference numeral 33 denotes a discharge control circuit; 35, an electrode 1;
A photodiode for detecting a discharge waveform from the arc light between 3 and 13; 37, an amplifier for amplifying the output v _{S of the} photodiode 35; 39, a band-pass filter for extracting only an AC component from the amplified v _S; A pulse width detection circuit 43 for detecting a pulse width, a framing processing circuit 43 for detecting a discharge duration, a calculator 45 for comparing the obtained pulse width and discharge duration with a target value, and a discharge circuit 47 for comparison. Time control signal (ON / OFF)
Discharge time output circuit for outputting
Is a pulse width output circuit that outputs a pulse width control signal (P _CONT ) obtained by comparison to the inverter 29, and 51 is a target value from the arithmetic unit 45 and a current value I from the current detector 31.
_This is a current control input / output circuit that outputs a current control signal (I _CONT ) obtained by comparing _S to the inverter 29. Next, a discharge control method using the circuit of FIG. 1 will be described with reference to FIG.
This will be described with reference to the timing chart of FIG. When a discharge time control signal (ON / OFF), a pulse width control signal (P _CONT ), and a current control signal (I _CONT ) are output from the discharge control circuit 33 to the inverter 29, a discharge occurs between the electrodes 13, 13. . When the discharge waveform at this time is detected by the photodiode 35, amplified by the amplifier 37, and passed through the band-pass filter 39, for example, the discharge time control signal shown in FIG. A waveform is obtained. The pulse width detection circuit 41 samples this discharge waveform with a clock having a frequency sufficiently higher than that frequency (preferably 10 to 16 times, preferably 16 times or more) and encodes the value. The state of this processing is shown in FIG.
To (e). (C) is an enlargement of the discharge waveform of (b) by almost one cycle, and (d) is a sampling clock. In this example, to simplify the illustration,
The clock frequency is set to eight times the discharge frequency. By this sampling, the discharge waveform is encoded with three potentials. That is, the high potential is {1}, the low potential is {0}, and the intermediate potential is {N}. The code string thus obtained is (e)
It is. The pulse width detection circuit 41 obtains the discharge pulse width and the duty ratio from the code string of (e) and sends them to the calculator 45. The discharge pulse width can be obtained from the number of consecutive {1}, and the duty ratio can be obtained as the ratio of the discharge pulse width to one cycle (eight symbols). In the illustrated example, since the discharge waveform of (c) is a sine wave, it is shown that {1} are continuous four (half cycle). However, since pulse width control is actually performed,
The continuous number of {1} is smaller than this. The pulse width detection circuit 41 further encodes the code string of (e) as shown in (f) and sends it to the framing processing circuit 43. At this time, the encoding is performed using eight codes (e) (one cycle) as one unit and {N} is 8 as shown in FIG.
{S} when the sequence is continuous, and {S} when the sequence of {0} comes after the sequence of {1} in eight consecutive codes.
Bar｝. {S} is a cycle in which no discharge occurs, and {S bar} is a cycle in which discharge occurs. The framing processing circuit 43 checks the code string of (f) and outputs one of the actually generated discharges that has continued for a predetermined time or more as one frame. For example, FIG.
As shown in (g), the start of the frame (discharge start) when three {S bars} come continuously, and the end of the frame (end of discharge) when four {S} come continuously. )
And FIG. 4 shows a finite state diagram of the framing process. The actual discharge duration can be determined from the framing flag thus obtained. Also, if there are two or more frames within one discharge time, it can be understood that the discharge is interrupted halfway. The arithmetic unit 45 compares the value input from the pulse width detection circuit 41 with the target value, sends a corrected value to the pulse width output circuit 49, and outputs the corrected value from the framing flag input from the framing processing circuit 43. , And compares this with a target value, and sends a corrected value to the discharge time output circuit 47. Thus, the next discharge is controlled by the corrected value. Note that the pulse width can be corrected in real time while one discharge is continued. If an abnormality such as interruption of discharge occurs repeatedly, the arithmetic unit 45 issues an alarm to an external display device or the like. In this way, the operator can take prompt measures for the abnormality. [Embodiment 2] FIG. 5 shows another embodiment of the present invention. In this embodiment, the discharge waveform is detected by a current waveform detector 53 on a conductor connecting the discharge electrode 13 and the power supply 15 for discharge. The current i _S detected by the current waveform detector 53 is an alternating current. Other configurations and operations are the same as those of the first embodiment.
The same portions are denoted by the same reference numerals and description thereof will be omitted. [Embodiment 3] FIG. 6 shows still another embodiment of the present invention. 6, the same parts as those in FIG. 1 are denoted by the same reference numerals. This embodiment differs from the first embodiment in that signal processing in the discharge control circuit 33 is performed by the CPU 55. That is, the discharge waveform obtained by the band pass filter 39 is converted into the first A / D converter 57.
A / D conversion is performed and input to the CPU 55, where a process for calculating a discharge pulse width, a duty ratio, and a discharge duration is performed, and these values are respectively compared with target values. Circuit 47 and first D / A
Output to the converter 59 to control the discharge time and pulse width. On the other hand, the current value I _S detected by the current detector 31 is A / D converted by the second A / D converter 57 and input to the CPU 55, where it is compared with the target value, and the obtained correction value is converted to the second value. D
Output to the / A converter 63 to control the current value. The rest is the same as in the first embodiment, and a description thereof will be omitted. As described above, according to the present invention, an actual discharge waveform which is affected by changes in all parameters such as an air state and an electrode surface state is detected, and the discharge time is determined based on the detected discharge waveform. In addition, since the pulse width is controlled, it is possible to appropriately control the amount of heat generated in the discharge in response to changes in all parameters. Further, when an abnormality such as interruption of discharge occurs, an alarm can be issued, so that the abnormality can be promptly dealt with.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block circuit diagram showing one embodiment of the present invention. FIGS. 2A to 2G are timing charts of signal processing in the circuit of FIG. 1; FIG. 3 is an explanatory diagram showing an encoding method in the circuit of FIG. 1; FIG. 4 is a finite state diagram of a framing process of a discharge duration in the circuit of FIG. 1; FIG. 5 is a block circuit diagram showing another embodiment of the present invention. FIG. 6 is a block circuit diagram showing still another embodiment of the present invention. FIG. 7 is a block circuit diagram showing a conventional discharge control method. FIGS. 8A and 8B are waveform diagrams showing a discharge time command and a discharge waveform when discharge is normal. 9A and 9B are waveform diagrams showing a discharge time command and a discharge waveform when discharge is abnormal. [Description of Signs] 11: Optical fiber 13: Discharge electrode 15: Discharge power supply 27: DC power supply 29: Inverter 31: Current detector 33: Discharge control circuit 35: Photodiode 37: Amplifier 39: Bandpass filter 41: Pulse Width detection circuit 43: framing processing circuit 45: arithmetic unit 47: discharge time output circuit 49: pulse width output circuit 51: current control input / output circuit

Claims (1)

(57) [Claim 1] A discharge waveform between discharge electrodes is detected by a sensor, a discharge pulse width and a discharge duration are obtained from the detected discharge waveform, and these are compared with target values to discharge. Controls pulse width and discharge time , and detects detected discharge waveform
Detects interruption of discharge within the time required to sustain discharge from
If the discharge interruption time is longer than
A discharge control method for an optical fiber fusion splicer, wherein an alarm is issued when interruption of power is repeatedly generated .