JP2584727B2 - Detecting device for foreign matter in dielectric by microwave - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a dielectric substance, mainly a foreign substance contained in an elongated dielectric substance such as cloth, yarn, fiber, etc. The present invention relates to a device for detecting a conductive substance.

[Conventional technology]

Japanese Patent Application Laid-Open Nos. 59-214748 and 60-67844 disclose the same type of detection device, but these devices detect foreign matter in a dielectric to be measured when high voltage or high power is applied. It is to detect a discharge phenomenon occurring at a conductive material and to know the intrusion of foreign matter.

On the other hand, those using microwaves as signals are disclosed in
The invention described in -20138 is known, but a waveguide is used for a microwave transmission line, and a dielectric to be measured is put in the waveguide to detect foreign substances in the dielectric. It is.

[Problems to be solved by the invention]

However, the former foreign substance detecting means using high voltage or large power has a problem in safety, and the apparatus itself becomes large. The latter foreign substance detecting means is not suitable for a large-sized dielectric to be measured because the dielectric to be measured is inserted into the waveguide.

In addition, although not long, the measured dielectric product is transferred through the high-frequency irradiation chamber, and when the measured dielectric product contains a conductive substance which is a foreign substance, light emitted from the conductive substance is detected. Japanese Patent Application Laid-Open No. 60-19 / 1985
Although there is an invention described in Japanese Patent No. 6694, in this case, since a waveguide is used as a high-frequency irradiation chamber, it has the same problem as described above.

Furthermore, the above publication describes that the detection effect is improved if the electric field direction inside the high-frequency irradiation chamber and the transport direction of the dielectric to be measured obliquely intersect, but the dielectric to be measured crosses the inside of the waveguide. Therefore, the crossing angle of the direction of transport of the dielectric to be measured with respect to the direction of the electric field is substantially constant.

Therefore, if the transfer direction of the dielectric to be measured including the foreign matter whose size, length, direction with respect to the transport direction, etc. is completely unknown is fixed, it is difficult to accurately detect the foreign matter.

An object of the present invention is to provide a small and highly operable detection device capable of easily detecting a foreign substance (conductive substance) contained in a dielectric cloth, a dielectric fiber, a dielectric plate or other long dielectrics. Aim.

[Means for solving the problem]

According to the present invention, a pair of metal strips are arranged on a dielectric substrate in parallel with an appropriate gap between the strips, thereby forming a microwave transmission slot line at the gap, and forming one of the slot lines. A microwave source is disposed at one end and a microwave detector is disposed at the other end, and the long dielectric to be measured is moved on the metal strip in a direction crossing the microwave transmission slot line. This is a device for detecting foreign matter in a dielectric.

(Operation)

The microwave transmitted from the microwave transmission source propagates to the transmission slot line. When the long dielectric to be measured is transferred on the metal strip so as to intersect the slot line, the dielectric to be measured is electromagnetically coupled.

Since an electromagnetic change occurs between the state in which no foreign substance is contained in the long dielectric to be measured and the state in which the foreign substance is contained,
This relative electromagnetic change is detected by the microwave detector.

This electromagnetic change is detected as a reflected wave, an insertion loss, or a change in impedance, and the signal output thereof is processed by a computer, whereby the presence of a foreign substance in the elongated dielectric to be measured can be known.

〔Example〕

Figure 1 - Figure 3 is a pair of metal strips (or strip metal foil) on the dielectric substrate 1 2 ₁ and 2 ₂ at appropriate gap 3 between the plate mutually arranged in parallel, the The gap 3 forms a microwave transmission slot line.

A high-frequency power source G as a microwave transmission source is connected to one end of the microwave transmission slot line, and a microwave detector (not shown) is connected to the other end. As the microwave detector, there is a non-reflection terminal that detects a reflected wave, or a power detector that detects a change in passing power. The microwave detector is connected to a computer so that the detection signal obtained by the detector is processed by a computer.

FIG. 2 is a cross-sectional view of the microwave transmission slot line 3, which is a flat or cloth-like, that is, a long dielectric material T _{1 to} be measured.
The describes a state in which is transported along the plate surface of the metal strip 2 ₁ and 2 _2.

Figure 3 shows a state that is transferring the measured dielectric T ₂ of the fibrous.

The intersection angle θ between the long dielectric material T ₁ · T ₂ and the microwave transmission slot line 3 may be a right angle, but the dielectric material T ₁ · T ₂
The foreign substance f (conductive substance) contained in T ₂ or the like can be said to be fine, and its length, size, direction with respect to the transfer direction of the dielectric, and the like are not constant. ₁・ T ₂
And the microwave transmission slot line 3 are changed to various angles. Long dielectric material T ₁・ T ₂
Is optional such as a belt conveyor type or a batch type.

According to the experiment, a fibrous metal piece f having a diameter of about 10 μm and a length of about 5 mm contained in a cloth-like dielectric having a thickness of several mm was detected using a microwave having a frequency of 10 GHz. In addition, diameter 10μ
It was possible to detect foreign matter of about 2 mm in length.

4 shows a pair of modified example of the arrangement of the metal strip 2 ₁ and 2 ₂ to form a microwave transmission slot line. There are two types, one with and without the ground plate 4 in FIG. (B) is a coplanar waveguide,
FIG. 3C shows an H-shaped guide.

〔The invention's effect〕

As described above, the foreign substance detection device of the present invention has a microwave transmission slot line with a simple structure in which a pair of metal strips are arranged on a dielectric substrate in parallel with an appropriate gap provided between the plates. The microwave transmission source is formed at one end of the microwave transmission slot line, and the microwave detector is arranged at the other end, thereby constituting the foreign matter detection device. Therefore, the entire detection device is miniaturized and installed. It takes up little space and is easy to carry.

Since the dielectric to be measured is transported on the metal strip of the detection device in a direction intersecting with the microwave transmission slot line, the dielectric to be measured is particularly suitable for detecting foreign substances in a long dielectric to be measured. When crossing the microwave transmission slot line, a minute change in impedance appears at the portion coupled to the microwave, so that high-resolution foreign object detection is possible.

The microwave source can be at a single frequency,
When the sweep frequency is used, a signal corresponding to each frequency from one foreign substance can be obtained, and there is an effect that the resolution for detecting the foreign substance is improved.

In addition, the configuration in which the dielectric to be measured is transported across the metal strip plate of the detection device so as to intersect with the microwave transmission slot line is compared to transporting the dielectric to be measured across a conventionally known waveguide. Since the dielectric to be measured is transported in the open state, even if the dielectric to be measured is long, it is easy to set and replace the dielectric to be measured with respect to the detection device.
A foreign substance detection device that can be freely changed to various angles, such as making the crossing angle between the long dielectric to be measured and the microwave transmission slot line oblique, to enhance the sensitivity to foreign substances, and The operability of the long dielectric to be measured is excellent.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view of a foreign matter detection device according to the present invention, FIG.
FIG. 3 is a perspective view showing the procedure for detecting foreign matter in a flat or cloth-like dielectric to be measured, FIG. 3 is a perspective view showing the procedure for detecting foreign matter in a fibrous dielectric to be measured, and FIGS. 4 (A), (B) and (C). () Is a vertical sectional front view of another embodiment of the detection device of the present invention. 1 ... dielectric substrate, 2 ₁ 2 ₂ ... metal strip, 3 ... microwave transmission slot line, 4 ... ground plate, G ... microwave source, T ₁ · T ₂ ... long Dielectric to be measured, f ... Foreign matter.

Claims (1)

(57) [Claims] 1. A microwave transmission slot line is formed by disposing a pair of metal strips on a dielectric substrate in parallel with an appropriate gap provided between the strips. A microwave transmission source is arranged at one end and a microwave detector is arranged at the other end, and the elongated dielectric to be measured is moved on the pair of metal strips in a direction intersecting with the microwave transmission slot line. The microwave detector detects the relative electromagnetic change between a normal dielectric to be measured and the same type of dielectric to be measured containing foreign matter, and detects the presence of the foreign matter based on the detection signal. Characteristic device for detecting foreign matter in dielectric using microwaves.