JPS63284486A - Detector for conductive material in glass fiber - Google Patents

Abstract

PURPOSE:To perform good-accuracy detection with simple constitution by passing a glass fiber which is a specimen continuously through a high-frequency electric field generated by a high-frequency transmitter. CONSTITUTION:A high-frequency chamber 2 of a waveguide type is used to a detector and the glass fiber 3 which is the specimen is continuously passed through this chamber 2. A signal output level is raised over the entire part of the frequency range by generation of a high-frequency discharge if a conductive material such as metal exists in the fiber 3 passing the inside of the chamber 2. Since the output PC 0 at the frequency fC apart sufficiently from the oscillation frequency f0, PC/P0 is extremely large. On the other hand, P0 is at the extremely high level and, therefore, SN log(P0/PC) decreases largely. The change in the SN is continuously monitored by a computer 5 using a spectral analyzer 4, by which the conductive material such as metal incorporated in the fiber 3 is detected with the good sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for detecting conductive substances in glass fibers.

[Conventional technology]

Foreign matter may be mixed into the glass fiber during its raw materials or during the manufacturing process. There are various types of foreign substances, including gold, silver, platinum, iron, nickel, etc.
Alternatively, conductive substances such as these intermetallic compounds or sulfides may impair the insulation properties of glass fiber processed products when they are used as insulating materials for printed wiring boards and the like.

As a technique for detecting such minute conductive foreign matter in glass fibers, there is a technique disclosed, for example, in Japanese Patent Application Laid-Open No. 59-214748.

In this known technique, a glass fiber as a test object is placed in a high-frequency electric field, a high-frequency discharge is caused in the glass fiber portion containing a conductive substance, and the light or sound generated at the time of this discharge is detected. It is designed to detect conductive foreign substances in fibers.

[Problem that the invention seeks to solve]

In the method disclosed in JP-A No. 59-214748 mentioned above, since the types and shapes of the metal substances contained in the glass fibers are diverse, the color and intensity of the light, the pitch of the sound,
The timbre, intensity, etc. change in various ways, and there are metals that are difficult to generate high-frequency discharges and metals that have low high-frequency discharge levels and are difficult to generate light or sound, so it has sometimes been impossible to detect them.

[Means for solving problems]

In the present invention, for example, as shown in FIG. 1, a glass fiber 3, which is an object to be examined, is continuously passed through a high-frequency electric field generated by a high-frequency oscillator 1.

For example, as shown in FIG. 3, an output Po at an oscillation frequency f0 of the high-frequency oscillator 1 and an output P at a frequency fc sufficiently distant from the oscillation frequency f0.

and calculate the SN ratio 101og (Pa /Pc) from these outputs Po and Pc.
Continuously monitor changes in ratio.

[Effect]

If there is no conductive substance in the glass fiber, pc
=o, and the S/N ratio is quite large. On the other hand, if a conductive substance is present in the glass fiber passing through a high-frequency electric field,
For example, as shown in Figure 4, the overall signal level rises, but since Po is at a very high level, Po'/Po
#l, and since Pc'/Pc becomes extremely large, SN
The ratio decreases significantly. Therefore, by monitoring this change in the S/N ratio, it is possible to detect whether or not a conductive substance is present in the glass fiber.

[Example〕 FIG. 1 is a schematic diagram showing a first embodiment of the present invention.

In this embodiment, a waveguide type high frequency chamber 2 is used, and a glass fiber 3 which is the object to be examined is placed in this high frequency chamber 2.
is passed continuously. Glass fiber 3 as the test object
The material may be a monofilament such as a monofilament or a strand, or a woven glass fiber processed product. The glass fiber 3 is passed through the high frequency chamber 2 at a predetermined speed by running guide means such as a supply reel, a take-up reel, and a guide roller (not shown).

In the high frequency chamber 2, the oscillator 1 generates a frequency of several tens of MHz.
A high frequency electric field of several GHz is formed. Then, the frequency distribution within this high frequency chamber 2 is analyzed by a spectrum analyzer 4 and a computer 5.

If there is no conductive substance such as a metal substance in the glass fiber 3 passing through the high frequency chamber 2, a frequency distribution with a high peak at the oscillation frequency f0 of the oscillator 1 is obtained, as shown in Fig. 3. . Therefore, while measuring the output Po at the oscillation frequency f0 of this oscillator 1,
The output Pc at a frequency fc sufficiently distant from this oscillation frequency f0 is measured as the background noise level at the comparison frequency, and from these Po and Pc, the SN ratio =
101og (P(1/Pc) to computer 5
Calculated in At this time, if the oscillator 1 with a sufficiently good signal-to-noise ratio is used, the signal-to-noise ratio will be P, .O, and therefore the signal-to-noise ratio of the detection output will be a sufficiently large value.

On the other hand, if a conductive substance such as metal is present in the glass fiber 3 passing through the high frequency chamber 2, the signal output level will increase over the entire frequency range due to the generation of high frequency discharge, as shown in FIG. . At this time, as mentioned above, Pc! =f
Since it is O, Pc'/P.

becomes extremely large, and on the other hand, Po is at a very high level, so it is Pa''/Po1l. Therefore, in the case of Fig. 4, the S/N ratio is 1101o (Po'/Pc'
) decreases significantly. By continuously monitoring changes in the S/N ratio using the computer 5, conductive substances such as metals mixed in the glass fibers 3 can be detected.

It is preferable that the comparison frequency f is selected within the range of several k)lz to several GHz. In this case, since the noise pattern differs depending on the type of mixed metal, it is preferable to select it so that Pc' is as large as possible. good.

It should be noted that by selecting a plurality of comparison frequencies fc, it is also possible to detect many types of metal substances with high accuracy.

FIG. 2 shows a second embodiment of the invention.

In this embodiment, a high-frequency chamber 12 in the form of a box-shaped oven is used, and the glass fiber 3 to be examined is passed between high-frequency oscillation electrodes 13 connected to an oscillator 1. A detection electrode 14 is provided near the high-frequency oscillation electrode 13, and the high-frequency signal detected by the detection electrode 14 is analyzed by the spectrum analyzer 4 and computer 5 in the same manner as in the first embodiment described above. The conductive foreign matter in the glass fiber 3 is detected.

As for oscillator 1, its oscillation frequency is several lOMH.
It is preferable to use a device with an output of 2 to several GHz to several hundreds of W to several tens of watts, and a device with a sufficiently high Q of the oscillation output and a good S/N ratio. On the other hand, spectrum analyzer 4
It is best to use one with a large Guinamiso clean range.

〔Effect of the invention〕

In the present invention, since the occurrence of high-frequency discharge within a high-frequency electric field is detected by directly detecting changes in the high-frequency electric field, it is possible to achieve reliable and accurate detection relatively unaffected by the type of conductive foreign object. Good detection can be done. Furthermore, since the SN ratio of the high frequency electric field is monitored, highly accurate detection can be performed with a simple configuration. Furthermore, by appropriately selecting the comparison frequency, it is possible to deal with a wide range of types of conductive foreign objects.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a detection device according to one embodiment of the present invention, FIG. 2 is a schematic diagram of a detection device according to another embodiment, and FIGS. 3 and 4 are relationships between the output of a spectrum analyzer and frequency. This is a graph showing. In addition, in the symbols used in the drawings, ■−・−・−・−・−−1−−−−Oscillator 2
−・・−・−−−1−−High frequency chamber 3−・−・−・−
・・・−・・Glass fiber 4・・−・・−−m−−−・−
- Spectral part th5 - - Computer 12 - - - - - - - High frequency chamber.

Claims (1)

[Scope of Claims] A high-frequency oscillator for generating a high-frequency electric field, means for continuously passing a glass fiber as an object through the high-frequency electric field, and an output of the high-frequency electric field at the oscillation frequency of the high-frequency oscillator. means for detecting P_o; means for detecting the output P_c of the high-frequency electric field at a comparison frequency sufficiently distant from the oscillation frequency of the high-frequency oscillator; and an S/N ratio of 10 log (P_o/
A detection device for a conductive substance in glass fibers, comprising means for calculating P_c) and monitoring means for continuously monitoring changes in the SN ratio.