JPH10185839A - Detector for conductive material in glass fiber woven fabric - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detector for a conductive material in glass fiber woven fabric wherein such effects of a glass fiber as thickness, wrinkle, water content, etc., are eliminated, and at the same time, as seen in resonance method, unstable phenomenan in detection sensitivity occurring due to the presence of strong/weak in an electric field between a wave node and the wave antinode of a standing wave is eliminated, and such conductive material as of a minute filament of, for example, 5mm or less can be detected with sure over the entire of the glass fiber woven fabric. SOLUTION: Two rectangular guide-waves 6a and 6b, comprising a non- reflection terminator 7b, provided with a slit for a glass fiber 11 to pass are placed, side by side, while inclined to a transportation direction of the glass fiber 11, and these rectangular guide-waves 6a and 8b are supplied with microwaves, while rivers in direction from each other, whose phases are displaced mutually from a microwave oscillator 1, and a reflection wave caused by a conductive material in the glass fiber woven fabric is detected with a wave detector 8a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus capable of simply and accurately detecting a conductive substance contained in a woven glass cloth (cloth).

[0002]

2. Description of the Related Art Foreign matter may be mixed in a glass woven fabric, particularly in a glass fiber constituting the same, in a raw material or a manufacturing process. These foreign substances are mainly conductive substances such as metal compounds and sulfides. These conductive substances in woven glass fabric, for example, when used in printed circuit boards, etc., impair the insulation of the electric signal circuits formed on the board, which causes significant problems. May be. Therefore, in a process of manufacturing a glass woven fabric, it is required to detect a conductive substance existing in the glass woven fabric in advance and to sufficiently control the quality of the glass woven fabric.

Conventionally, methods for detecting a conductive substance contained in a glass woven fabric include a method using a change in dielectric constant, a method using a microwave phase difference, and a method using microwave resonance. Attempted.

However, in these known detection methods, the dielectric constant of the glass woven fabric changes minutely due to the difference in the thickness or wrinkles of the fiber of the glass woven fabric or the moisture content of the glass woven fabric. Since the signal level also changes, it is difficult to detect at a stabilized high sensitivity level. In addition, in the case of the method using the resonance method, the electric field distribution in the longitudinal direction of the slit waveguide that transmits microwaves while passing through a glass woven fabric always has a node (wave motion) at the same position on the line. The point where the absolute value of the amplitude is the smallest)
And the antinode (the point where the absolute value of the amplitude of the wave is the maximum), that is, a standing wave exists. Therefore, the detection sensitivity of the conductive substance passing near the antinode is high, On the contrary, there is a disadvantage that the detection sensitivity of the conductive substance passing near the node is reduced.

On the other hand, in recent years, electric wiring circuits formed on a printed circuit board have been becoming more and more dense. Therefore, in a glass woven fabric incorporated in a printed circuit board, for example, a wire having a length of 5 mm or less is used. Even in the case where the conductive material having the shape is present, it is regarded as defective, and the allowable range of the conductive material present in the glass woven fabric is becoming smaller.

[0006]

SUMMARY OF THE INVENTION The present invention eliminates the influence of the thickness and wrinkles of the glass fiber and the water content, and at the same time, as shown by the resonance method, the connection between the nodes and antinodes of the standing wave. Eliminates the instability of detection sensitivity caused by the presence of an electric field between the electrodes. For example, it is possible to reliably detect a conductive substance consisting of a fine linear body with a length of 5 mm or less over the entire width of a glass cloth. It is an object of the present invention to obtain a device for detecting a conductive substance in a glass woven fabric, which can perform the following.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has an anti-reflection terminator.
At least two or more waveguides provided with slits through which the glass woven fabric is provided are arranged side by side inclining with respect to the direction of transport of the glass woven fabric. By supplying microwaves which are opposite to each other and are out of phase with each other, the reflected wave generated by the conductive material in the glass woven fabric is detected by a detector. It is a detection device.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiment of the present invention shown in FIG. 1 will be described below.

[0009] 1 9,389~9,411MH _z, for example, a microwave oscillator for generating microwaves of a reference frequency 9,400MH _z, modulator microwaves oscillated built in microwave oscillator by, for example, those that can be modulated in a range of ± 11MH _z relative frequency 9,400MH _z. The microwave output from the microwave oscillator 1 is divided into two by a distributor 2 and supplied to two lines A and B, respectively.

In the first line A, the output from the distributor 2 is supplied to a circulator 3a, a matching unit 4a, and a phase shifter 5a.
Is supplied to the rectangular waveguide 6a. This rectangular waveguide 6
The microwave having passed through a reaches the non-reflection terminator 7a. The microwave arriving there is completely absorbed by the radio wave absorber incorporated in the non-reflection terminator 7a and is radiated out of the system as heat energy. Is reflected and does not return toward the rectangular waveguide 6a. Also in the second line B, the output from the distributor 2 passes through the circulator 3b, the matching unit 4b, and the phase shifter 5b, and passes through the rectangular waveguide 6b.
Is supplied to the rectangular waveguide 6b having the same structure as the above. The microwaves passing through the rectangular waveguide 6b reach the non-reflection terminator 7b, and the microwaves reaching the non-reflection terminator 7b become heat energy and are radiated out of the system as in the case of the A line. You.

Here, due to the inherent attenuation characteristics of the rectangular waveguides 6a and 6b, the traveling directions of the microwaves supplied to the rectangular waveguides 6a and 6b are configured to be opposite to each other. Circulator 3a. Reference numeral 3b is for sending reflected waves generated in the rectangular waveguides 6a and 6b to the detectors 8a and 8b via the phase shifters 5a and 5b and the matching devices 4a and 4b. The matching devices 4a and 4b are rectangular waveguides 6a and 6b.
This is for matching the load impedance on the side.

The phase shifters 5a and 5b are for adjusting the phase of the microwave, and are non-reflection terminators 7a and 7b.
Has a role of absorbing all traveling waves that have passed through the rectangular waveguides 6a and 6b, and preventing the traveling waves from being reflected there.

Slits 9a and 9b are formed in the rectangular waveguides 6a and 6b along the longitudinal direction thereof at both centers of the long sides, and the glass weave to be detected is passed through these slits 9a and 9b. The cloth 11 is a rectangular waveguide 6a, 6
b.

The reflected waves generated by the conductive material inside the glass woven cloth 11 passing through the rectangular waveguides 6a and 6b are detected by the circulators 3a and 3b.
b, and the detectors 8a and 8b convert the reflected wave into an analog signal by the action of a diode built in the detector and transmit the analog signal to the signal processing alarm transmitter 10.

The signal processing alarm transmitter 10 has two lines A and B.
Amplifies the respective signals transmitted from the detectors 8a and 8b, and causes differences in fiber thickness, wrinkles, variations in dielectric constant and moisture content, and fluctuations in the glass woven cloth 11, which are factors specific to glass woven cloth. It has a function to remove irregular signals (disturbance signals) generated by vibrations, etc. at the time, and selects only signals corresponding to reflected waves generated by a conductive substance contained in glass woven fabric, Is output to the outside as an alarm signal based on

In the embodiment of the present invention, as shown in FIG. 2A, the distance d between the axes of the short waveguides 6a and 6b is set so that the microwaves transmitted to both waveguides do not interfere with each other. It is determined. That is, it is desirable to be about 50 to 100 mm, for example, 98 mm. The rectangular waveguide 6a as shown in FIG. 2 (b), inner dimension (a × b) of 6b of the cross-section, the frequency of the microwave 8,200MH _z ~12,400MH
_z can be transmitted in the range of, for example, 22.9 mm × 1
Use the one with 0.2 mm. In addition, in order to detect a conductive substance contained in either the weft x or the warp y of the glass woven fabric 11, the axial direction of the rectangular waveguides 6a and 6b is set in the transport direction of the glass woven fabric 11. On the other hand, it is inclined by ∠α. The reason is as follows.

FIG. 3 is a schematic view showing a state of existence of a conductive substance contained in glass fibers constituting the glass woven fabric 11. The glass woven fabric 11 is obtained by weaving a bundle of a plurality of glass fibers as a weft x and a warp y, and the conductive substance P contained in the glass woven fabric 11 is converted into a glass fiber as a linear body having a small diameter. Inherent. On the other hand, the detection of the conductive substance by the microwave is performed by the microwave transmitted to the rectangular waveguides 6a and 6b colliding with and reflecting the conductive substance. Since the conductive substance P contained in the glass cloth 11 is a linear body having a very small diameter, for example, the transfer direction of the glass woven cloth 11 is set to the warp y direction, and the rectangular waveguide is formed with respect to the transfer direction of the glass woven cloth 11. When 6a and 6b are arranged at right angles, the warp y
Microwaves can be detected by reflecting microwaves on the conductive substance P contained therein, but cannot be detected on the conductive substance P contained in the weft yarn x because the reflection of microwaves hardly occurs. .

Therefore, in the present invention, the rectangular waveguides 6a, 6b
Is tilted by Δα with respect to the transport direction of the glass woven fabric 11, microwaves can be reflected on the conductive substance P contained in the weft yarn x and the warp yarn y, and detection becomes possible. If the inclination angle α is, for example, 45 °, the conductive substance P can be detected with the same detection sensitivity in the directions of the weft x and the warp y.

Further, the microwave transmitted to the rectangular waveguides 6a and 6b collides with the conductive substance P existing in the glass woven cloth 11 and is reflected, and the reflected waves are reflected by the detectors 8a and 8b.
8b, the rectangular waveguides 6a, 6
Inside b, a standing wave is formed in which the traveling wave of the microwave and the reflected wave are combined. As shown in (a) of [I] of FIG.
2 and an antinode 13, and the interval between the antinode 13 and the antinode 13 is, for example, a frequency of 9,400 MHz.
_In the case of _z , it is approximately 22 mm and is always constant. The interval between antinodes points adjacent consistent with guide wavelength lambda] g / 2 when the microwave transmitting the TE ₁₀ mode.

However, from the microwave transmission theory, it is known that the electric field becomes maximum at the antinode 13 of the standing wave, and the electric field becomes minimum at the node 12 of the standing wave. ] (A) as shown in FIG.
In the case of a standing wave in which the conductive substance P is contained in the detector 1, when the vicinity of the antinode 13 is taken into the detector, the detection can be performed with high sensitivity. , The detection performance is degraded. As described above, the positions of the antinode 13 and the node 12 of the standing wave, that is, the antinode 1 of the standing wave are taken into the detector.
Whether the vicinity is 3 or the vicinity of the node 12 is determined by where in the glass woven fabric 11 the conductive substance P is present. Considering this relationship as a distribution of detection possibility in the longitudinal direction of the rectangular waveguide, it becomes as shown in FIG.

Therefore, in the present invention, in order to eliminate such inconvenience, two detection circuits are provided, and the phase of the microwave transmitted to the rectangular waveguides 6a and 6b is changed by [II] in FIG.
As shown in FIG. 4A, the phase shifters 5a and 5b make adjustments so that they are shifted from each other by λg / 4, and as a result, [I
As shown in (b) of I), the two are combined so as to always exhibit high detection performance. Also, the above phase shifter is
For example, when detecting a glass woven cloth having a different width dimension, the wavelength of the standing wave generated there is slightly shifted. This means that detection can be performed with the highest sensitivity.

When a microwave is transmitted inside a waveguide provided with a slit on either one of the lines A and B in FIG. 1, the amount of attenuation of the microwave is important. While the attenuation per unit length when generally using conventional rectangular waveguide provided with no slits is transmitted microwave 9,400MH _z is substantially 0.11 dB / m, the same When a microwave having the above frequency is transmitted to a waveguide having a shape and a slit provided with a slit, the attenuation is about 1,13 dB / m, which is about 10 times as large as the above case. Is found as a result of actual measurement.

According to this result, the performance of detecting a conductive substance in the case of a single-line slit of either the line A or the line B gradually decreases as approaching the non-reflection terminator side. become.

Therefore, the present invention provides a means for eliminating the above-mentioned disadvantages by using two lines, in which the traveling directions of microwaves are opposite to each other in the rectangular waveguides 6a and 6b in the lines A and B, respectively. Is adopted, the presence or absence of a conductive substance can be reliably detected in all portions of the glass woven fabric 11.

As described above, the two signals transmitted from the detectors 8a and 8b enter the signal processing alarm transmitter 10. The signal processing alarm transmitter 10 has a circuit for amplifying the signal processing input signal and an irregular vibration generated when the glass woven cloth 11 moves, a change in the dielectric constant or the water content of the glass woven cloth, and the like. Remove the signal as a disturbance signal,
The circuit comprises a circuit for selecting only a signal corresponding to a reflected wave generated by a conductive substance contained in the glass woven fabric, and a circuit for transmitting an alarm signal to the outside based on the selected signal. By configuring such a function, malfunctions due to unnecessary signals are eliminated, and for example, a minute conductive material having a diameter of about 1 μm and a length of about 3 mm can be detected, so that highly reliable detection can be performed.

FIG. 5 shows an example in which an output signal obtained by detecting a conductive substance is recorded by using an oscilloscope.
When there is a conductive substance, a peak waveform is shown in this manner. The higher the height of the peak protruding upward in this figure, the easier it is to compare with the characteristic changes caused by various disturbance elements, so that it is possible to reliably detect even a minute conductive substance, The result of the detection can ensure high reliability.

Although the embodiment of the present invention has been described in detail above, the present invention is not limited to this embodiment.
Other changes and modifications are possible. For example, although a rectangular waveguide is used for each of the two systems of waveguides in the above embodiment, a waveguide having a circular or other shape may be used. In addition, although the A-system waveguide and the B-system waveguide are separately configured, the same object can be achieved by using a double waveguide in which these are integrated.

In the embodiment, the microwave oscillator is 1
The output is distributed by a distributor and supplied to two lines. Of course, a microwave oscillator may be independently connected to each of the two lines. Furthermore,
If the number of waveguides is two or more, the detection capability can be further improved.

[0029]

According to the present invention, there is an excellent effect that a defect caused by an extremely minute conductive substance existing in a glass woven fabric can be reliably detected over the entire glass woven fabric.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2A is a plan view showing an arrangement of waveguides according to an embodiment of the present invention, and FIG. 2B is an enlarged sectional view taken along line AA in FIG.

FIG. 3 is a schematic view of a state of presence of a conductive substance.

FIG. 4 is an explanatory diagram of a standing wave.

FIG. 5 is a diagram showing an example of a detection waveform shown on an oscilloscope.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Microwave oscillator 2 Divider 3a, 3b Circulator 4a, 4b Matching device 5a, 5b Phase shifter 6a, 6b Waveguide 7a, 7b Non-reflection terminator 8a, 8b Detector 9a, 9b Slit 10 Signal processing alarm transmitter 11 Glass woven cloth

Claims (1)

[Claims] At least two waveguides having an anti-reflection terminator and provided with slits for passing a glass woven fabric are arranged side by side with respect to the direction of transport of the glass woven fabric. It is assumed that microwaves whose traveling directions are opposite to each other and whose phases are shifted from each other are supplied to these waveguides from a microwave oscillator, and a reflected wave generated by a conductive material in the glass woven fabric is detected by a detector. Characteristic device for detecting conductive substances in glass woven fabric.