JP2000162321A - Metallic object detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly detect a metallic object by providing an air-core coil as a coil for generating a magnetic flux inside a passage hole where the metallic object passes through. SOLUTION: A coil bobbin 2 of a detector body 1 comprises a winding barrel 2a around which a coil wire is wound and flanges 2b at both ends, while a coil 3 is formed by winding a coil wire around the winding barrel 2a to be a coreless coil. The coil 3 constitutes an LC resonance circuit together with an internal circuit inside the detector body 1 and generates a high frequency magnetic flux ϕpassing inside a passage hole 1a with the LC resonance circuit driven. When a pachinko ball passes through the passage hole 1a while the coil 3 generates a high frequency signal, eddy current occurs on a surface of the pachinko ball to consume energy of the high frequency magnetic flux ϕ. Thus oscillation amplitude of the high frequency magnetic flux ϕ drops or oscillation stops to allow passage of the pachinko ball through the passage hole 1a to be detected. In addition, erroneous detection may not occur without an iron core through which a magnetic flux from an external magnet might pass to cause magnetic saturation, thereby allowing correct detection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal object detecting device for detecting a metal object such as a pachinko ball.

[0002]

2. Description of the Related Art Conventionally, there is an apparatus of this type shown in FIGS. This is a pachinko ball detector, detector body A, iron core B, coil
Has C Detector main body A, apertures A ₁ is provided to pass through the pachinko ball is a metal object, such that the coil C of the apertures A ₁ coil wire to the outside is wound is formed, the coil wire is wound iron core B is arranged consisting of flange portion B ₂ which is provided on the winding body B ₁ and both ends of the winding body B ₁ is wrapped.

[0003] coil C of this product, along with an internal circuit provided inside the detector body A (not shown), without the LC resonance circuit, by which the LC resonant circuit is driven, the passage holes A ₁ Generates a high-frequency magnetic flux Φ passing inside.

Next, the operation of the above device will be described. coil
In a state where C is generating high frequency signals, the pachinko balls in the passage hole A ₁ passes, an eddy current is generated on the surface of the pachinko balls, the energy of the high-frequency magnetic flux Φ is depleted,
RF magnetic flux oscillation amplitude Φ is stopped or the oscillation decreases, based on the reduction or oscillation stop of such oscillation amplitude, it is possible to detect the pachinko ball that passes through the passage hole A _1.

[0005]

In the above-mentioned conventional metal object detecting device, for example, when an external magnet such as a permanent magnet is disposed in proximity, an iron core penetrated by a magnetic flux generated from the permanent magnet. Since B is magnetically saturated, the high-frequency magnetic flux Φ
As a result, an erroneous detection that the pachinko ball is passing though the pachinko ball which is a metal object is not passing is caused.

Further, the intended, for the coil C to coil wire to the outside of the passage hole A ₁ is wound is formed, has a larger coil C than the interior of the coil wire passing hole A ₁ Therefore, with such a large coil C, the antenna effect on the disturbance radio wave becomes large, and due to the noise due to the disturbance radio wave, it is impossible to accurately detect the passage of the pachinko ball which is a metal object. There is a risk that it will.

[0007] Further, as shown in FIGS. 5 and 6, when two are disposed adjacent to each other, the high-frequency magnetic flux Φ generated by the coil C of both metal object detection devices interacts. That is, when the passage hole A ₁ of one of the metal object detecting apparatus pachinko ball passes, if originally for pachinko ball has passed through the passage hole A _1, is the energy of the high-frequency magnetic flux Φ is depleted, lowering of the oscillation amplitude or Where the oscillation stops, the high-frequency magnetic flux Φ is supplied from the coil C of the other metal object detection device, the oscillation amplitude does not decrease, and the passage of the pachinko ball, which is a metal object, cannot be accurately detected.

The present invention has been made in view of the above points, and an object of the present invention is to provide a metal object detecting device capable of accurately detecting a metal object.

[0009]

In order to solve the above-mentioned problems, the invention according to claim 1 comprises a through-hole through which a metal object passes, a coil that generates a magnetic flux passing through the inside of the through-hole,
And a metal object detection device that detects a metal object passing through the passage hole based on a change in magnetic flux, wherein the coil is an air-core coil.

According to a second aspect of the present invention, there is provided a through hole through which a metal object passes, and a coil which is wound with a coil wire and generates a magnetic flux passing through the inside of the through hole. In the metal object detecting device for detecting the metal object passing through the through hole, the coil is arranged such that the inside of the coil wire is located outside the through hole.

According to a third aspect of the present invention, there is provided a through hole through which a metal object passes, and two coils each of which is wound with a coil wire and generates a magnetic flux passing through the inside of the through hole.
In a metal object detection device that detects a metal object passing through the passage hole based on a change in magnetic flux, both coils generate a magnetic flux having the same magnetic moment in the opposite direction and the absolute value, Each of the coil wires connected in series is wound.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. This metal object detection device is a pachinko ball detector, and includes a detector main body 1, a coil bobbin 2, and a coil 3.

The detector main body 1 is provided with a passage hole 1a through which a pachinko ball as a metal object passes. Coil bobbin
Numeral 2 is made of a molding material and includes a winding drum 2a around which a coil wire is wound, and flanges 2b provided at both ends of the winding drum 2a.

The coil 3 is formed by winding a coil wire as described above. Since the coil 3 does not have an iron core on which a coil wire is wound, it is an empty coil, and includes an LC resonance circuit together with an internal circuit (not shown) provided inside the detector main body 1. When the LC resonance circuit is driven, a high-frequency magnetic flux Φ passing through the inside of the passage hole 1a is generated. Also, this coil 3
Constitutes the coil device 10 together with the coil bobbin 2 described above.

In the coil device 10, two coils 3 are provided at the periphery of the passage hole 1a so that the axial direction of the coil 3 is directed to the passage hole 1a. It is easier to pass. Thus, the coil device 10 is
The coil 3 is arranged such that the inside of the coil wire is located outside the passage hole 1a.

In the two coil devices 10 described above, the respective coils 3 are connected in series, and the magnetic moments M of the generated high-frequency magnetic flux Φ have the same absolute value and are opposite to each other. The coils 3 are formed by winding the respective coil wires.

Next, the operation of this device will be described. coil
When a pachinko ball passes through the passage hole 1a in a state where 3 is generating a high-frequency signal, an eddy current is generated on the surface of the pachinko ball, and the energy of the high-frequency magnetic flux Φ is consumed.
The oscillation amplitude of the high-frequency magnetic flux Φ decreases or the oscillation stops, and it is possible to detect that the pachinko ball has passed through the passage hole 1a based on the decrease in the oscillation amplitude or the stop of the oscillation.

In such a metal object detecting device, the coil 3, which is an air-core coil, does not have an iron core penetrated by magnetic flux generated from an external magnet and magnetically saturated.
The pachinko ball will not be erroneously detected as passing though the pachinko ball has not passed, and the pachinko ball can be accurately detected.

Since the inside of the coil wire is located outside the passage hole 1a, a small coil 3 whose inside is smaller than the passage hole 1a can be formed. Is formed, the antenna effect on external radio waves can be reduced, noise due to disturbance radio waves can be reduced, and pachinko balls can be accurately detected.

The high-frequency magnetic flux Φ generated by each of the two coils 3 has the same absolute value in the opposite direction. For example, the point P shown in FIG. 2 cancels out each other. By arranging another metal object detection device so that the through-hole 1a is located in a region where the high-frequency magnetic flux Φ cancels each other, the pachinko ball passes through the through-hole 1a and the energy of the high-frequency magnetic flux Φ The high-frequency magnetic flux Φ is no longer supplied from the coil 3 of the other metal object detection device to the one metal object detection device side that has been consumed, and the passage of a pachinko ball that is a metal object is accurately detected. be able to.

In this embodiment, the configuration in which the coil 3 is an air-core coil, the configuration in which the coil 3 is disposed so that the inside of the coil wire is located outside the passage hole 1a,
Has a configuration in which coil lines connected in series are wound to form a coil 3 so that magnetic fluxes having the same absolute value are generated in opposite directions to each other, but the pachinko ball is detected sufficiently accurately. If it is possible, only one or two components may be provided.

Further, in the present embodiment, the coil wire is wound around the coil bobbin 2 to form the coil 3, but the coil wire is not wound around another member such as the coil bobbin 2.
Even if only the coil wire itself is wound to form the coil 3, the effect that pachinko balls can be detected accurately can be achieved.

In this embodiment, the pachinko ball is detected. However, the present invention is not limited to the pachinko ball, but can accurately detect other metal objects.

[0024]

According to the first aspect of the present invention, the coil, which is an air-core coil, has no iron core penetrated by the magnetic flux generated from the external magnet and magnetically saturated. Regardless, it is not possible to erroneously detect that a metal object is passing, and the metal object can be accurately detected.

According to the second aspect of the present invention, since the inside of the coil wire is located outside the through hole, a small coil whose inside of the coil wire is smaller than the through hole can be formed. By forming a coil of
The antenna effect on external radio waves can be reduced, noise due to disturbance radio waves can be reduced, and metal objects can be accurately detected.

According to the third aspect of the present invention, since the absolute values of the magnetic moments of the magnetic fluxes generated by the two coils are the same in opposite directions, there is a region where the magnetic moments cancel each other. By arranging another metal object detection device so that the passage hole is located in the area,
When the pachinko ball passes through the passage hole and the energy of the high-frequency magnetic flux is consumed, the high-frequency magnetic flux is not supplied from the coil of the other metal object detecting device to the one metal object detecting device side. Can be detected accurately.

[Brief description of the drawings]

FIG. 1 is a plan view showing a configuration of an embodiment of the present invention.

FIG. 2 is a plan view showing a state where magnetic fluxes generated from two coils of the above are canceled at arbitrary points.

FIG. 3 is a plan view of a conventional example.

FIG. 4 is a cross-sectional view showing the configuration of the above.

FIG. 5 is a plan view showing a state where the above components are arranged adjacent to each other.

FIG. 6 is a cross-sectional view showing a state where the above-mentioned components are arranged adjacently.

[Explanation of symbols]

 1a Passage hole 3 Coil Φ High frequency magnetic flux

Claims (3)

[Claims] 1. A metal object detection device comprising: a passing hole through which a metal object passes; and a coil that generates a magnetic flux passing through the inside of the passing hole, wherein the metal object detecting the metal object passing through the passing hole based on a change in the magnetic flux. In the apparatus, the coil is an air-core coil. 2. A through hole through which a metal object passes, and a coil wound with a coil wire to generate a magnetic flux passing inside the through hole, and passing through the through hole based on a change in the magnetic flux. A metal object detection device for detecting a metal object, wherein the coil is disposed so that the inside of the coil wire is located outside the passage hole. 3. A through hole through which a metal object passes, and two coils each wound with a coil wire and each generating a magnetic flux passing inside the through hole, based on a change in the magnetic flux. In a metal object detection device that detects a metal object passing through a passage hole, the coils are connected in series so that both coils generate magnetic fluxes having the same magnetic moment in the opposite direction to each other. A metal object detection device characterized by being wound.