JP3613916B2 - Detection device for conductive substances in glass fabric - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus capable of easily and accurately detecting a conductive substance contained in a glass woven cloth (cloth).
[0002]
[Prior art]
In the glass woven fabric, particularly in the glass fiber constituting it, foreign materials may be mixed in in the raw material or in the process of production. These foreign substances are mainly conductive substances such as metal compounds and sulfides. These conductive materials in glass woven fabrics, for example, when used for printed circuit boards, impair the insulation of the electrical signal circuit constructed on the circuit board, thereby causing important problems There is a case. Therefore, in the process of manufacturing a glass woven fabric, it is required to detect in advance a conductive substance present in the glass woven fabric and to sufficiently control the quality of the glass woven fabric.
[0003]
Conventionally, as a method for detecting a conductive substance contained in a glass woven fabric, (1) a method using a change in dielectric constant, (2) a method using a phase difference of microwave, and (3) microwave resonance. Attempts have been made to use the method.
[0004]
However, in these known detection methods (1) and (2), the dielectric constant of the glass woven fabric slightly changes due to the difference in fiber thickness and wrinkles of the glass woven fabric or the moisture content of the glass woven fabric. Therefore, since the detection signal level also changes, it is difficult to detect at a stable and highly sensitive level. Further, in the case of the method using the resonance method (3), the electric field distribution in the longitudinal direction of the slit waveguide that transmits the microwave while passing through the glass woven fabric is always at the same position on the line. Since there is a wave in the form of (the point where the absolute value of the wave amplitude is the minimum) and the wave antinode (the point where the absolute value of the wave amplitude is the maximum), that is, a standing wave exists, Although the detection sensitivity of the conductive substance passing through is high, the detection sensitivity of the conductive substance passing through the vicinity of the wave node is low.
[0005]
On the other hand, in recent years, electrical wiring circuits formed on printed circuit boards tend to have a higher density. For this reason, in glass woven fabrics incorporated into printed circuit boards, for example, from a linear body having a length of 5 mm or less. Even when the conductive material is contained, it is regarded as defective, and the allowable range of the conductive material contained in the glass woven fabric is becoming smaller.
[0006]
[Problems to be solved by the invention]
The present invention eliminates the influence of glass fiber thickness, wrinkles, moisture content, etc., and at the same time, as seen by the resonance method, there is an electric field strength between the standing wave nodule and the antinode. Conductivity in a glass woven fabric that can reliably detect a conductive substance composed of a fine linear body having a length of 5 mm or less, for example, over the entire width of the glass fabric without the unstable phenomenon of detection sensitivity caused by An object is to obtain a substance detection device.
[0007]
[Means for Solving the Problems]
The present invention has been made in order to solve the above-described problems. At least two waveguides having a non-reflective terminator and provided with slits for passing the glass woven fabric are transferred to the glass woven fabric. The conductive materials in the glass woven fabric are arranged in parallel with each other, and are supplied with microwaves whose traveling directions are opposite to each other and out of phase with each other. The apparatus detects a conductive substance in a glass woven fabric, wherein a reflected wave generated by the wave is detected by a detector.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the embodiment of the present invention shown in FIG. 1 will be described.
[0009]
1 is a microwave oscillator which oscillates microwave 9,389～9,411MH _z, for example, the reference frequency 9,400MH _z, by a modulator microwaves oscillated built in microwave oscillator, e.g. 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.
[0010]
In the first line A, the output from the distributor 2 is supplied to the rectangular waveguide 6a through the circulator 3a, the matching unit 4a, and the phase shifter 5a. The microwave that has passed through the rectangular waveguide 6a reaches the non-reflecting terminator 7a. The microwaves that have reached there are all absorbed by the electromagnetic wave absorber incorporated in the non-reflective terminator 7a and are dissipated out of the system as thermal energy. Once the microwaves reach the non-reflective terminator 7a Does not reflect back to the rectangular waveguide 6a. Also in the second line B, the output from the distributor 2 is supplied to the rectangular waveguide 6b having the same structure as the rectangular waveguide 6b via the circulator 3b, the matching unit 4b, and the phase shifter 5b. The Then, the microwave that has passed through the rectangular waveguide 6b reaches the non-reflecting terminator 7b, and the microwave that has reached the non-reflecting terminator 7b is dissipated out of the system as thermal energy in the same way as the A line. The
[0011]
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 opposite to each other. Circulator 3a. 3b sends the 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 units 4a and 4b. The matching units 4a and 4b are for matching the load impedances on the rectangular waveguides 6a and 6b side.
[0012]
The phase shifters 5a and 5b are for adjusting the phase of the microwave, and the non-reflection terminators 7a and 7b absorb all the traveling waves that have passed through the rectangular waveguides 6a and 6b. It has a role to prevent reflection.
[0013]
In the rectangular waveguides 6a and 6b, slits 9a and 9b are formed at both centers of the long side surfaces along the longitudinal direction thereof, and the glass woven fabric 11 to be detected is detected through these slits 9a and 9b. It passes through the rectangular waveguides 6a and 6b.
[0014]
Reflected waves generated by the conductive material inherent in the glass woven fabric 11 passing through the rectangular waveguides 6a and 6b are sent to the detectors 8a and 8b by the circulators 3a and 3b. The detectors 8a and 8b The reflected wave is converted into an analog signal by the action of the diode incorporated in the signal and transmitted to the signal processing alarm transmitter 10.
[0015]
The signal processing alarm transmitter 10 amplifies each signal transmitted from the detectors 8a and 8b of the two lines A and B, and the difference in fiber thickness, wrinkles, dielectric constant, It has the function of removing irregular signals (disturbance signals) generated by fluctuations in moisture content, vibrations when the glass woven fabric 11 moves, etc., and is generated by a conductive substance present in the glass woven fabric. Only the signal corresponding to the reflected wave is selected and output to the outside as an alarm signal based on the signal.
[0016]
In the embodiment of the present invention, as shown in FIG. 2a, the distance d between the axial centers of the short waveguides 6a and 6b is determined in such a range that the microwaves transmitted to both waveguides do not interfere with each other. . That is, about 50-100 mm is desirable, for example, it is set to 98 mm. The rectangular waveguide 6a as shown in FIG. 2 (b), inner dimension (a × b) of 6b cross-section, which the frequency of the microwave can be transmitted in the range of 8,200MH _z ~12,400MH _z Then, for example, the one with 22.9 mm × 10.2 mm is used. In addition, the axial direction of the rectangular waveguides 6a and 6b is set in the transport direction of the glass woven fabric 11 in order to detect a conductive substance contained in either the weft x or the warp y of the glass woven fabric 11. On the other hand, it is inclined by ∠α. The reason is as follows.
[0017]
FIG. 3 is a schematic view showing a state of existence of a conductive substance inherent in the glass fiber constituting the glass woven fabric 11. The glass woven fabric 11 is made by weaving a plurality of bundles of glass fibers as wefts x and warps y, and the conductive substance P contained in the glass woven fabric 11 is made into a glass fiber as a fine-diameter linear body. Is inherent. On the other hand, the detection of the conductive material by the microwave is performed when the microwave transmitted to the rectangular waveguides 6a and 6b collides with and reflects the conductive material. 11 is a linear body having a very small diameter. For example, the direction of transport of the glass woven fabric 11 is the warp y direction, and a rectangular waveguide is formed with respect to the direction of transport of the glass woven fabric 11. When 6a and 6b are arranged at right angles, the microwave can reflect and detect the conductive material P contained in the warp y, but the conductive material P contained in the weft x can be detected. On the other hand, since the reflection of the microwave hardly occurs, it cannot be detected.
[0018]
Accordingly, in the present invention, the rectangular waveguides 6a and 6b are inclined by ∠α with respect to the transfer direction of the glass woven fabric 11, so that the microwave is applied to the conductive material P existing in the weft x and the warp y. It can be reflected and becomes detectable. If the inclination angle α is set to 45 °, for example, the conductive substance P can be detected with the same detection sensitivity in the directions of the weft x and the warp y.
[0019]
Further, the microwaves transmitted to the rectangular waveguides 6a and 6b collide with the conductive material P existing in the glass woven fabric 11 to cause reflection, and the reflected waves bounce back to the detectors 8a and 8b. As a result, a standing wave in which the traveling wave of the microwave and the reflected wave are combined is formed inside the rectangular waveguides 6a and 6b. This standing wave becomes a wave having a wave node 12 and an antinode 13 at the same position of the waveguide as shown in FIG. 4 [I] (a). spacing and 13, for example when the frequency is 9,400MH _z, always constant substantially 22mm next. The interval between the adjacent antinodes coincides with the in-tube wavelength λg / 2 when the microwave is transmitted in the TE ₁₀ mode.
[0020]
However, it is known from the microwave transmission theory that the electric field is maximized at the antinode 13 of the standing wave, and conversely, the electric field is minimized at the wave node 12, and therefore (I) in FIG. As shown in a), in the standing wave when the conductive material P is inherent in the glass woven fabric 11, when the vicinity of the antinode 13 is taken into the detector, it can be detected with high sensitivity. On the other hand, when the vicinity of the wave node 12 is taken into the detector, the detection performance is degraded. As described above, the position of the antinode 13 and the node 12 of the standing wave, that is, the vicinity of the antinode 13 or the node 12 of the standing wave is taken into the detector, the conductive substance P is glass. It depends on which position of the woven fabric 11 is present. If this relationship is considered as a distribution of detection availability in the longitudinal direction of the rectangular waveguide, it becomes as shown in (b) of [I] in FIG.
[0021]
Therefore, in the present invention, in order to eliminate such an inconvenience, two detection circuits are provided, and the phase of the microwave transmitted to the rectangular waveguides 6a and 6b is as shown in (a) of [II] in FIG. The phase shifters 5a and 5b are adjusted so as to be shifted from each other by λg / 4, and as a result, as shown in (b) of [II] in FIG. It is like that. In addition, when the above phase shifter detects, for example, glass cloths having different width dimensions, the wavelength of the standing wave generated there is slightly shifted, and even in such a case, the phase shifters 5a and 5b By adjusting the phase shift, detection can always be performed with the highest sensitivity.
[0022]
In either one of the lines A and B in FIG. 1, when microwaves are transmitted through a waveguide provided with slits, the attenuation amount of the microwaves 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 dimension having a slit, the attenuation amount is approximately 1,13 dB / m, which is approximately 10 times that of the above case. Is found as a result of actual measurement.
[0023]
According to this result, the detection performance of the conductive material in the case of the single row slit of either the line A or B gradually decreases as it approaches the non-reflection termination side.
[0024]
Therefore, in the present invention, as means for eliminating the above problems, the lines A and B constitute two lines in the rectangular waveguides 6a and 6b that are opposed to each other with the microwave traveling directions opposite to each other. By adopting this method, it is possible to reliably detect the presence or absence of a conductive substance for all portions of the glass woven fabric 11.
[0025]
As described above, the two signals transmitted from the detectors 8 a and 8 b enter the signal processing alarm transmitter 10. This signal processing alarm transmitter 10 is an irregular circuit that is generated due to a circuit that amplifies the signal processing input signal and vibration generated when the glass woven fabric 11 moves, a change in the dielectric constant or moisture content of the glass woven fabric, and the like. From the circuit that removes the signal as a disturbance signal, selects only the signal corresponding to the reflected wave generated by the conductive material inherent in the glass woven fabric, and the circuit that transmits the alarm signal to the outside based on the selected signal It is configured. By configuring such a function, malfunction due to unnecessary signals is eliminated, and even a minute conductive material having a diameter of about 1 μ and a length of about 3 mm can be detected, so that highly reliable detection is possible.
[0026]
FIG. 5 illustrates an example in which an output signal obtained by detecting a conductive substance is recorded using an oscilloscope, and when there is a conductive substance, a peak waveform is shown. In this figure, the higher the peak that protrudes upwards, the easier it is to compare with changes in characteristics caused by various disturbance elements, so even minute conductive substances can be detected reliably. The detected result can be highly reliable.
[0027]
As mentioned above, although one Example of this invention was explained in full detail, this invention is not limited to this Example, Other changes and corrections are possible. For example, in the above-described embodiment, rectangular waveguides are used for the two waveguides, but circular or other waveguides 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-type waveguide in which these are integrated.
[0028]
In the embodiment, one microwave oscillator is provided, and the output is distributed by a distributor and supplied to two lines. Of course, the microwave oscillator is independently provided to each of the two lines. You may make it join. Furthermore, if the number of waveguides is two or more, the detection capability can be further improved.
[0029]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, there exists the outstanding effect that the defect by the very minute electroconductive substance which exists in a glass woven fabric can be reliably detected over the whole glass woven fabric.
[Brief description of the drawings]
FIG. 1 is a block diagram of an embodiment of the present invention.
2A is a plan view showing the arrangement of waveguides in an embodiment of the present invention, and FIG. 2B is an enlarged cross-sectional view taken along line AA in FIG.
FIG. 3 is a schematic diagram showing the existence state of a conductive substance.
FIG. 4 is an explanatory diagram of a standing wave.
FIG. 5 is a diagram illustrating an example of a detection waveform appearing on an oscilloscope.
[Explanation of symbols]
1 Microwave Oscillator 2 Dividers 3a and 3b Circulators 4a and 4b Matching Units 5a and 5b Phase Shifters 6a and 6b Waveguides 7a and 7b Non-reflective Terminators 8a and 8b Detectors 9a and 9b Slit 10 Signal Processing Alarm Transmitter 11 Glass woven fabric

Claims (1)

At least two or more waveguides having a non-reflective terminator and provided with slits through which the glass woven fabric passes are arranged in parallel to be inclined with respect to the transport direction of the glass woven fabric. A glass weaving characterized in that a microwave oscillator feeds microwaves whose traveling directions are opposite to each other and out of phase with each other, and a reflected wave generated by a conductive material in the glass weaving cloth is detected by a detector. Detection device for conductive substances in cloth.

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