WO2006046358A1

WO2006046358A1 - Apparatus equipped with high frequency coil

Info

Publication number: WO2006046358A1
Application number: PCT/JP2005/016700
Authority: WO
Inventors: Tsutomu Mizuno
Original assignee: Shinshu University
Priority date: 2004-10-28
Filing date: 2005-09-06
Publication date: 2006-05-04
Also published as: JPWO2006046358A1

Abstract

A conductive body detecting/measuring device which has a coil (11) facing in non-contact a conductive body (20), and a voltage measuring unit (19) for measuring an output voltage from the coil (11), and which detects and measures the conductive body by measuring with the voltage measuring unit (19) a change in output voltage from the coil (11) caused by eddy current flowing inside the conductive body (20) due to high-frequency electromagnetic induction oscillated by the coil (11), wherein the wire (10) of the detection coil (11) is a copper wire (1) covered on the outer periphery thereof with magnetic layers (3, 5). A high-frequency transformer provided with at least a primary-side coil (25) and a secondary-side coil (27), wherein the wires (10) of the coils (25, 27) are copper wires covered on the outer peripheries thereof with the magnetic layers (3, 5).

Description

Equipment equipped with high frequency coil

Technical field

The present invention provides an apparatus provided with a high frequency coil for exciting an electromagnetic wave, specifically, an apparatus for detecting and measuring a conductive object, a proximity switch, and a high frequency coil.

It relates to a high frequency transformer. book

Background art

When an electromagnetic wave is oscillated from a high frequency coil, it is known that an electromagnetic induction current flows to a conductive object in the magnetic field. Various sensors have been developed using the eddy currents induced by such high frequency coils. For example, Japanese Patent Application Laid-Open No. 9-270,700 discloses a gap sensor for preventing shock to a laser processing head. Also, Japanese Patent Application Laid-Open No. 7-8360 non-contact measurement of clearance for wood chip refinement machine, Japanese Patent Application Laid-open No. 2 0 0 2-4 7 7 3 is a force cutter used for excavating work. The distance measurement of the drive shaft, the thickness detection of the image recording paper is disclosed in JP-A-11-160430, the determination of the metal material is disclosed in JP-A-8-185749, and the A variety of sensors, such as magnetic bearings, are disclosed in Japanese Utility Model Application Publication No. 2-201101. The high frequency coils used in these various sensors are usually wound with enameled insulated copper wire.

An eddy current proximity switch is one that uses the same principle as these various sensors. In addition to the eddy current type, the proximity switch also has a capacitance type, a magnetic type that captures changes in the DC magnetic field, etc., and generates a switch signal by detecting an approaching conductive object without contact. Contact like a micro switch Therefore, high response, long life, and high reliability can be expected compared to those that produce switch signals. Above all, eddy current proximity switches are able to distinguish between magnetic and nonmagnetic properties to be measured, and are easy to miniaturize, and are not susceptible to external magnetic fields. They are expected to be used in industrial applications. There is.

The method disclosed in Japanese Utility Model Publication No. 4 2-1 3 3 9 improves the high frequency gain when the enameled insulated wire having a ferromagnetic mesh on the copper wire circumference is used for the wire for high frequency ring. It discloses what to get. In addition, JP-A-62-12094 describes an inductor made of a copper wire with a magnetic material attached on the surface. Brief description of the drawings

FIG. 1 is a cross-sectional view of one embodiment of a wire used in the coil of an apparatus to which the present invention is applied.

FIG. 2 is a diagram showing magnetic flux lines when current is supplied to the wire.

FIG. 3 is a diagram showing the strength of the magnetic field according to the distance from the coil.

FIG. 4 is a circuit diagram showing one embodiment of a conductive object detection and measurement apparatus to which the present invention is applied.

FIG. 5 is a view showing the positional relationship between the conductive object and the detection coil in the detection and measurement device of the embodiment.

FIG. 6 is a graph comparing measured values of equivalent series resistance between a coil used in the detection and measurement device of the present invention and a conventional coil.

FIG. 7 is a graph comparing measured values of equivalent inductances of a coil used in the detection and measurement device of the present invention and a conventional coil.

FIG. 8 is a graph comparing the measured values of the high frequency gain Q value of the coil used in the detection and measurement device of the present invention and the conventional coil.

Fig. 9 shows the change in resistance with the distance between the conductive object and the detection coil. It is rough.

FIG. 10 is a graph showing the inductance by the distance between the conductive object and the detection coil.

FIG. 11 is a graph showing the high frequency gain Q value depending on the distance between the conductive object and the detection coil.

FIG. 12 is a graph showing the output voltage according to the distance between the conductive object and the detection coil.

FIG. 13 is a graph showing the linearity of the output voltage characteristic depending on the distance between the conductive object and the detection coil.

FIG. 14 is a graph showing the sensitivity according to the distance between the conductive object and the detection coil.

FIG. 15 is a cross-sectional view of an essential part of a flaw detection sensor which is an embodiment of a conductive object detection and measurement apparatus to which the present invention is applied.

FIG. 16 is a cross-sectional view of a high frequency transformer to which the present invention is applied.

FIG. 17 is a block diagram of a proximity switch to which the present invention is applied. FIG. 18 is a cross-sectional view of a coil used in a proximity switch to which the present invention is applied.

FIG. 19 is a cross-sectional view of another embodiment of a wire used for a coil of an apparatus to which the present invention is applied. Explanation of sign

1 is a copper wire, 3 is an iron layer, 5 is a nickel layer, 7 is an insulating layer, 8 is a magnetic flux line, 9 is a wire rod, 10 is a wire rod, 11 is a detection coil, 13 is a capacitor, 15 is a minute Capacitor for pressure, 17 for oscillator, 19 for voltmeter, 20 for conductive body, 23 for iron core, 25 for primary coil, 27 for secondary coil, 30 for crack, 32 for 32 Wire, 3 3 'is fusion layer, 35 is oscillation circuit, 36 is comparison Circuit, 37: output circuit, 40: magnetic core, _Ie : excitation current, _Ie : eddy current, 、 θ · θθ: magnetic flux, R (x): equivalent series resistance, L (x): inductor X is the distance between the conductive object and the detection coil.

Disclosure of the invention

Prior to the implementation of the invention, the inventor of the present invention conducted the following preliminary experiment and FEM (Finite Element Method: finite element method) analysis by a computer to obtain knowledge leading to the completion of the present invention.

First, a prototype coil and a conventional coil were created. As shown in detail in FIG. 1 (cross-sectional view), wire rod 10 of the trial coil (wire rod used for the coil of the device of the present invention) is a magnetic material on the core wire (outside diameter 90 im) made of copper wire 1 The iron layer 3 and the -Keckle layer 5 which are layers are laminated, and the insulating layer 7 of polyurethane is applied to the outside. The wire 10 was used as a coil with an inner diameter of 1.6 mm, an outer diameter of 2.24 mm, an axial length of 0.63 mm, and a number of N = 26 times.

The conventional coil has the same number and shape as a wire material in which a polyurethane insulation layer is coated on the outer periphery of a copper wire (core wire outer diameter 90 m).

(1) FEM analysis (software Maxwell) was used to obtain flux lines when current was applied to the coil. The analysis conditions were f = 1.4 MH z and I _c = 1 mA. As shown in Fig. 2 (A), the distribution of magnetic flux lines 8 around wire 10 of the prototype coil and the distribution of magnetic flux lines 8 around wire 9 of the conventional coil shown in Fig. 2 (B). The shielding effect shows that magnetic flux is less likely to enter the inside of the wire than conventional coils.

(2) The current density at the wire cross section when current was applied to the coil was obtained by FEM analysis. Prototype coil wire 10 is a conventional coil wire Less bias in current density distribution than material 9. The wire of the trial coil has a magnetic flux which is hard to enter inside the wire due to the shielding effect of the magnetic layer, but in the conventional coil, the magnetic flux is inside of the conductor and this magnetic flux causes an eddy current to flow inside the wire. . In the case of a trial coil that is hard to contain magnetic flux, the bias of the current density distribution is smaller than that of the conventional coil. Therefore, the current density distribution has a resistance increase due to the bias (proximity effect), so the resistance of the conventional coil is larger than that of the prototype coil.

(3) The strength of the magnetic field due to the distance from the coil was determined by FEM analysis. As shown in Fig. 3, it was found that the magnetic field strength of the prototype coil was larger than that of the conventional coil when the distance r was separated.

The present invention was made under the findings as described above, and provides an apparatus provided with a high-inductance high-frequency coil for exciting an electromagnetic wave, and in detail, it has excellent detection sensitivity and wide detection. A detection and measurement device for conductive objects that can obtain a range, a proximity switch with high sensitivity and excellent operation reliability that is not affected by the surrounding magnetic field, a motor actuator with a high power factor, and a high frequency transformer. It is said that.

The conductive object detection and measurement device according to the present invention, which has been made to achieve the above object, comprises a coil (11) facing the conductive object (20) without contact and a coil (11) connected to the coil (11). The coil (11) has a voltage measuring instrument (19), and an eddy current flowing inside the conductive object (20) by high frequency electromagnetic induction oscillated by the resonant (11). A device for detecting and measuring the conductive object (20) by measuring a change in output voltage of the high frequency oscillation device with the voltage measuring instrument, wherein a wire (10) of the high frequency oscillation coil (11) It is characterized by being a copper wire (1) covered with a layer (3. 5).

The detection and measurement object of the conductive object detection and measurement device of the present invention can be implemented as a detection of metals. That is, this detection and measurement device I mean Sa.

Similarly, the detection and measurement object of the conductive object detection and measurement apparatus of the present invention can be implemented as the distance (X) between the conductive object (20) and the coil (11). That is, this detection and measurement device means a distance sensor to the conductive object (20).

In addition, the detection and measurement object of the conductive object detection and measurement device of the present invention can be implemented as a scratch (3 0) inside the conductive object (2 0). That is, this detection and measurement device means a flaw detection sensor in a conductive object.

The proximity switch of the present invention, which has been made to achieve the above object, is connected to the coil (11) and the coil (11) to connect the oscillator circuit (35) and the comparison circuit (36). An eddy current having an output circuit (37) and an on / off signal from the output circuit (37) due to an induced current flowing to the coil (11) as the conductive object (20) approaches. It is characterized in that the wire (10) of the coil (11) is a copper wire (1) whose outer periphery is covered by a magnetic layer (3 * 5).

The high frequency transformer of the present invention made to achieve the above object comprises at least a primary coil (25) and a secondary coil (27), and the coil (25 · 2 7) The wire rod (10) is a copper wire (1) whose outer periphery is covered with a magnetic layer (3 * 5).

The magnetic layer on the outer periphery of the wire rod 10 of the core (1 1 · 2 · 5 · 2 7) used for the detection and measurement device of the present invention, proximity switch, or high frequency transformer is ferrite, iron, nickel, Cobalt, Fe-N, Fe-XN (X = Ta, Nb, Hf, etc.), Fe-X-〇 (X = Mg, Al, etc.), NiFe (Permalloy), CoFe, CoNiFe It can be carried out with at least one layer selected from soft magnetic materials such as CoFeB, FeP, NiFeP, CoNiFeMoC, CoFeB, CoNbZr できる Fe-Si, and the like.

Also, the magnetic layer is a layer of plated iron or Z and nickel. The effect of the invention is preferred

The coil used for the detection and measurement device, proximity switch, or high frequency transformer of the present invention uses a copper wire whose outer periphery is covered with a magnetic layer as a wire material, and the inductance is increased. Gain Q improves. In addition, since the shielding effect of the magnetic layer can prevent resistance 增 by the proximity effect of the eddy current, the sensitivity of the detection and measurement device is improved, the sensitivity of the proximity switch is improved, and the high frequency transformer is efficient. improves.

Comparing the distance from the coil of the detection and measurement device to the conductive object to be detected and measured and the output voltage of the coil, the output voltage of the coil used in the device of the present invention is a conventional copper wire The detection voltage is higher than the output voltage of the coil, and the detection range of the distance is wide. Example

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to these examples.

FIG. 4 shows a circuit diagram of one embodiment of a conductive object detection and measurement apparatus to which the present invention is applied. The conductive object detection and measurement device shown in the figure includes a distance sensor from the detection coil of the device to the conductive object, a metal detection sensor for detecting the presence of metals, and a flaw detection sensor for detecting the presence or absence of cracks in the conductive object. It can be used as

As shown in FIG. 4, a detection coil (high frequency oscillation coil) 11 faces the conductive object 20 without contact. The detection coil 1 1 has an equivalent series inductance L (x) and an equivalent series resistance R (x). detection The coil 1 1 is connected in parallel with the capacitor 1 3 to form a resonant circuit. An AC voltmeter 19 is connected to the resonant circuit. The detection coil 1 1 is connected to the oscillator 17 via a voltage dividing capacitor 15 for limiting the current.

The wire of the detection coil 1 1 used in the detection and measurement device for a conductive object of the present invention is a copper wire whose outer periphery is covered with a magnetic layer. As shown in detail in FIG. 1 (cross-sectional view), the wire 10 according to the embodiment of the present invention has a core wire made of a copper wire 1 with an iron layer 3 and an Eckel layer 5 as magnetic material layers. Insulating layer 7 of polyurethane is applied to Outer diameter of core wire of copper wire 1 is 90 / zm, outer diameter of iron layer 3 is 92 / xm (layer thickness 1 / zm), outer diameter of Nickel layer 5 is 92.1 μm (layer thickness 0.0 5 ix) rn) The Nikkol layer is provided to make it easy to attach solder.

This wire rod 10 is wound onto a bobbin of diameter 3.36 mm made of acrylic resin, with a length of 10.2 times and an axial length of 2.15 mm, coil outer diameter 4.5 4 mm (Koinore inner diameter 3. 3 6 mm, coil out differences thickness 0.5 9 mm, Koi Le mean radius = 1. ₉ 7 5 mm) of the embodiment of the detection coil 1 1 (hereinafter, examples coil and Re, cormorants also Yes).

For comparison, the same number of coils are applied to the outer periphery of a copper wire (core wire outer diameter 90 zm) with a wire material coated with an insulating layer of polyurethane and a conventional high frequency oscillation coil (hereinafter referred to as a comparative example coil) I assume.

The conductive object 20 to be measured is chromium molybdenum steel (S CM4 40) which is a magnetic substance in this embodiment.

In the case of the above detection and measurement apparatus, when the distance between the conductive object 20 and the coil 1 1 is X, the following operation is performed. The performance evaluation of the operation and equipment is described below.

Excitation voltage V (excitation frequency f = 1.4 MHZ) from the oscillator 17 of the device As shown in Fig. 5, a magnetic flux 0c is generated when an excitation current IC is supplied to the detection coil 1 1 by applying When the magnetic flux 0c acts on the conductive object 20, an eddy current I e flows in the conductive object 20 by electromagnetic induction to generate a magnetic flux. Since the magnetic flux acting on the conductive object 20 changes according to the distance X from the detection coil 1 1 to the conductive object 20, the eddy current I e flowing to the conductive object 20 changes, and as a result, The impedance of detection coil 1 1 changes. This change in impedance is converted to the output voltage Vo by the parallel resonant circuit. The measured resonant frequency of the output voltage vo measured at this time is f. = 10.5 MHz. The output voltage Vo is expressed by the following equation.

Q (x) = ω L (x) / R (x) (2)

k = 1 + C _P / C _s (3)

Here, x: distance from the conductive object to be measured to the detection coil, Q (x): Q value depending on distance X, V: excitation voltage [V], ω: angular frequency [rad / s], L (x): Inductance [HR (x): Resistance [Ω], C p: Resonant capacitor 1 3 CS: Voltage dividing capacitor 1 5

From the above equation, the output voltage Vo is expressed only by the Q (x) value of the coil and the capacitor capacitances C p and CS, and the measurement range of the detection and measurement device using parallel resonance shown in FIG. Indicates that the high frequency gain dependent on the coil Q (x H direct, ie, distance X) is affected.

Therefore, the equivalent series resistance R (x = ∞) with respect to the frequency of the example coil and the comparative example coil was measured and is shown in FIG. In the experiment, R (∞) of the example coil was approximately 1.5 times that of the comparative example coil. In the example coil, the proximity effect between the conducting wires is reduced by the Fe layer and the Ni layer, so the equivalent series resistance R (∞) is reduced compared to the comparative example coil. Figure 6 shows the comparison coil The calculated value of resistance by skin effect is shown.

Resistance due to the skin effect Rse is calculated by the following equation: γ berybei-beiyber'y

[Ω]

ber'-y + bei

Four_

πσά [Ω]

2

Here, Rdc: DC resistance of coil [Ω], 1: length of lead from start to end [m], σ: conductivity of lead [S / m], d: diameter of lead [m ], Ri: inner radius of coil [m], re: outer radius of coil [m], 8: skin thickness [m], / θ θ: relative permeability of wire, / O: permeability of vacuum (4 π Χ Ο ^{_ _ 7} ) [H / m], ber: 0th-order real Kelvin function, bei: 0th-order complex kelvin function.

Furthermore, Figure 6 shows that the increase in resistance to frequency is mainly due to the proximity effect. Also, the resonance frequency was 10.5MH z for all coils.

The equivalent series inductances for the frequencies of the example coil and the comparative example coil are shown in FIG. The equivalent series inductances L ()) of the example coil and the comparative example coil in the frequency range of f = 100 kHz to 2 MHz are 41 / z H and 37 // H, respectively. The example coil is 1.1 times as large as the comparative example coil. The frequency gain Q (∞) values of the example coil and the comparative example coil were measured and are shown in FIG. In the figure, the example coil has a 0 (∞) value of 1.6 times that of the comparative example coil. The reason is that the equivalent series resistance R (R) decreases and the equivalent series inductance L (∞) increases.

As shown in FIG. 9, the variation IR of the impedance characteristics R (X) of the example coil and the comparison coil is 31 1 Ω and 3 8 Ω, respectively, and the variation of the impedance of the coil is 1R. It is 1. 2 times that of the example coil, and it is clear that the impedance characteristic of the example coil is excellent. As the distance X decreases, a large magnetic flux 0c acts on the conductive object to be measured to increase the eddy current loss of the conductive object. Due to this, the impedance characteristic R (X) increases. In the example coil, a magnetic flux larger than that of the comparative example coil acts on the conductive object (see the prototype coil in FIG. 3 and the conventional coil). Therefore, as the distance X becomes smaller, the impedance R (X) of the example coil increases more than that of the comparative example coil.

As shown in FIG. 10, the inductance L (X) is constant with respect to the distance X between the example coil and the comparative example coil. The inductance L (x) of the example coil and the comparative example coil is 40 and 36 respectively, and the inductance L (X) of the example coil is 1.1 times as large as that of the comparative example coil. Ru. It is understood that the inductance L (x) of the example coil is larger than that of the comparative example coil by the effect of the magnetic thin film.

In addition, since the example coil has a large impedance variation 1R and a large inductance L (x), as can be seen from FIG. 11, the variation of the high frequency gain Q (x) value is compared to that of the comparative example coil. About twice that of

Figure 12 shows the comparison of the output voltage characteristics of the example coil and the comparative example coil The Also, the figure shows the approximate straight line using the least squares method for each of the output voltage characteristics. The amount of change in output voltage JVo was 430 mV for the conventional coil and 850 mV for the prototype coil, and the example coil was about twice the coil of the comparative example. Amount of change 1VO was calculated from the following equation.

AV _o = V _o (∞)-V _o (0. \) [V]

A comparison of the linearity of the output voltage characteristics of the example coil and the comparative example coil is shown in FIG. The output voltage characteristics shown in Fig. 12 are linearly approximated using the least squares method, and the distance between the approximate value and the actual value is kept within a range of ± 3% of the error e (X). The range L was determined. The error e (X) was calculated using the following equation.

Here, Vl (x): voltage [V] of approximate straight line.

The range in which the linearity of the output power is kept within ε (X) = ± 3% is, as shown in Table 1, between 0.1 and 2.2 mm and 0.1 to 1.6 mm for the example coil and the comparative example coil, respectively. is there. That is, the linear ranges L of the example coil and the comparative example coil are 2.1 mm and 1.5 mm, respectively. Further, the linear range L / D with respect to the outer diameter dimension D of the coil was 0.5 8 and 0.3 3 for the example coil and the comparative example coil, respectively. The linear range L / ra with respect to the average radius ra of the coil was 1.23 and 0.87 for the example coil and the comparative example coil, respectively. Both the L / D and L / ra values of the example coil were about 1.4 times that of the comparative example coil. In addition, as for Re, the gap of the gap is also D = 4.5 4 mm, ra = 1.73 mm. Therefore, the example coil is superior in linearity to the comparative example coil, and the expansion of the distance detection range of the conductive object detection and measurement device is realized. table

FIG. 14 shows a comparison of detection sensitivity of the conductive object detection and measurement device in the case of using the example coil and the comparative example coil. The detection sensitivity V ′ (X n) / X n at the n-th measurement point was calculated using the following equation.

Δ ^ ₀ ) _ M− i ^) _{[v / m} ] According to the figure, the detection sensitivity lVo '/ lx is up to 1 5 5 V / m for the coil of the comparative example and up to 3 1 0 V / m for the coil of the example. It became 1.5 times. At all distances, the example coil became more sensitive than the comparative example coil. Therefore, in the example coil, an improvement in distance detection sensitivity is realized as compared with the comparative example coil.

From the above results, it is possible to expand the distance measurement range and to improve the distance detection sensitivity compared to the conventional copper wire by using a magnetic plated wire for the coil of the conductive object detection and measurement device.

In the above embodiment, an example of the distance sensor capable of measuring the distance from the detection coil of the device to the conductive object has been described. However, a metal detection sensor for examining the presence / absence itself of the conductive object such as metal with the same configuration. It is apparent that the device using the example coil is more sensitive than the device using the comparative example coil, and the search range is wider. Further, FIG. 15 shows a cross section of a schematic configuration of an embodiment in which the above-mentioned detection and measurement device is used as a flaw detection sensor. As shown in this figure, measurement pairs When the conductive object 20 which is an elephant has a crack 30, the eddy current flowing inside the conductive object 20 changes due to the presence of the crack 30. As a result, the resonance output of the detection coil 1 1 changes, and the presence or absence of the crack 30 can be detected. Even when used as such a flaw detection sensor, the device using the example coil has higher sensitivity than the device using the comparative example coil, and the search range becomes wider.

FIG. 16 shows a cross section of an example of the high frequency transformer according to the present invention, in which an iron core 23 is wound with a primary coil 25 and a secondary coil 27. The wire of each of these coils 2 5 · 2 7 is a copper wire whose outer periphery is covered with a magnetic layer. The high frequency voltage input to the primary coil 25 is transformed and output from the secondary coil 27. '

An example of a high frequency transformer is a pulse transformer used in a DC-DC converter. A high frequency current is supplied to the primary coil 25 from an external electronic circuit (not shown). As shown in the comparison of series equivalent resistance R (∞) with respect to the frequency of the example coil of FIG. 6 and the comparative example coil, the resistance R of the example coil is smaller than that of the comparative example coil. That is, in the high frequency transformer, the copper loss generated in the coil can be reduced by configuring the coil using the magnetic soldered wire in which the outer periphery of the copper wire is covered with the magnetic thin film. It becomes high efficiency.

Although the transformer having the iron core is described in this embodiment, it may be an air core type transformer without the iron core. Since the example coil exerts more magnetic flux than the comparative example coil, that is, the magnetic flux can be blown further away, the air core transformer using the example coil can also realize high performance.

FIG. 17 shows the configuration of the proximity switch of the present invention and is of the eddy current type. It is connected to coil 1 1 and coil 1 1 and has an oscillation circuit 3 5, a comparison circuit 3 6 and an output circuit 3 7. Oscillator circuit 35 is in parallel with the coil and the coil The excitation current is supplied to the resonant circuit composed of connected capacitors, and the voltage (displacement) of the resonant circuit is output. The comparison circuit 36 compares the preset voltage (hereinafter referred to as the set displacement) with the output of the resonance circuit using the OP amplifier, and the displacement is less than the set displacement and the displacement is the set displacement or more. Output the corresponding voltage. The output circuit 37 outputs 0 V from the output of the comparison circuit 36 if the displacement is less than the set displacement, and outputs 5 V if the displacement is equal to or more than the set displacement.

As shown in FIG. 18, the coil 1 1 has a configuration in which a wire 10 shown in FIG. 1 is wound around a core 40 made of a soft magnetic material such as ferrite. In addition, coil 11 may be an air core coil without a core. The above-mentioned eddy current type proximity switch obtains a binary ON / OFF output voltage from the output circuit due to the induced current flowing to the coil near the dust of the conductive object 20.

With such a configuration, it is possible to suppress an increase in the alternating current resistance of the coil 1 1, to increase the inductance, and to cause a large amount of magnetic flux to act on the conductive object 20. The sensitivity distance to the conductive object 20 can be expanded, and miniaturization of the coil 1 1 can be realized.

In the cross-sectional view of wire rod 10 shown in FIG. 1, wire rod 10 has iron layer 3 and nickel layer 5 laminated to copper wire 1, but high permeability such as Ni Fe or ferrite A magnetic material having a magnetic permeability and a high resistivity may be formed by a process such as plating.

FIG. 20 is a cross-sectional view of a wire used in a coil of an apparatus to which the present invention is applied, which is another embodiment different from the example shown in FIG. In the wire 32 of this example, an iron layer 3 as a magnetic material layer and a nickel layer 5 are adhered to a core wire made of a copper wire 1, and an insulating layer 7 made of polyurethane is provided on the outer side. A fusion layer made of a thermoplastic resin is provided. this In the wire 32 of the example, it is possible to perform winding directly to the magnetic core while heating, and the fusion layer is melted to bond the wires together.

Claims

1. A coil having a noncontacting opposite to a conductive object, and a voltage measuring device connected to the coil, the eddy current flowing inside the conductive object due to high frequency electromagnetic induction generated by the coil A device for detecting and measuring the conductive object by measuring a change in output voltage of a coil with the measuring device,

The conductive object detection and measurement apparatus, wherein the wire of the high frequency oscillation coil is a copper wire whose outer periphery is covered with a magnetic layer.

2. The magnetic layer is made of ferrite, iron, nickel, cobalt, Fe-N, Fe-XN (X = Ta, Nb or Hf), Fe-X-- (X = Mg or Al) , NiFe,

The conductive object detection and measurement apparatus according to claim 1, wherein at least one layer selected from CoFe, CoNiFe, CoFeB, FeP, NiFeP, CoNiFeMoC, CoFeB, CoNbZr, and Fe-Si is used.

3. The conductive object detection and measurement device according to claim 1, wherein the magnetic material layer is a layer of plated iron or / and nickel.

4. The conductive object detection and measurement device according to claim 1, wherein the detection target of the conductive object is metal detection.

5. The conductive object detection / measurement apparatus according to claim 1, wherein a detection measurement target of the conductive object is a distance between the conductive object and the coil.

6. The conductive object detection and measurement apparatus according to claim 1, wherein the detection target of the conductive object is a flaw inside the conductive object.

7. A coil, and an oscillator circuit, a comparator circuit, and an output circuit connected to the coil, and an eddy that outputs an on / off signal from the output circuit by an induced current flowing to a coil as the conductive object approaches. A current-type proximity switch characterized in that the wire of the coil is a copper wire whose outer periphery is covered with a magnetic layer. Proximity switch.

8. The magnetic layer is ferrite, iron, nickel, cobalt, Fe-N, Fe-XN (X = Ta, Nb or Hf), Fe-X-- (X = Mg or Al), The proximity switch according to claim 10, wherein the proximity switch is at least one layer selected from NiFe, CoFe, CoNiFe, CoFeB, FeP, NiFeP, CoNiFeMoC3, CoFeB, CoNbZr, and Fe-Si.

9. The proximity switch according to claim 8, wherein the magnetic layer is a layer of plated iron or nickel.

10. A high frequency transformer comprising a high frequency transformer including at least a primary side coil and a secondary side coil, wherein the wire of the coil is a copper wire whose outer periphery is covered with a magnetic layer.

1 1. The magnetic layer is made of iron, nickel, cobalt, ferrite, Fe-N, Fe-XN (X = Ta, Nb, or Hf), Fe-X- ((X = Mg, or Al) The high frequency transformer according to claim 10, wherein the high frequency transformer is at least one layer selected from NiFe, CoFe, CoNiFe, CoFeB, FeP, NiFeP, CoNiFeMoC, CoFeB, CoNbZr and Fe-Si.

12. The high frequency transformer according to claim 10, wherein the magnetic layer is a layer of plated iron or nickel.