JP3072300B2 - Conductor detection method and apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus for detecting a difference between two conductors made of metal or the like, and in particular, to a container or cover made of a metal plate or a metal foil ( The present invention relates to a conductor detection method and apparatus suitable for detecting a conductor present inside a metal envelope.

[Conventional technology]

FIG. 3 is a block diagram showing an apparatus based on a conventional conductor detection method.

The conductor detection device 50 includes a bridge circuit 56 having a detection coil 52 and a reference coil 54, an oscillator 58 for exciting the bridge circuit 56, an amplifier circuit 60 for amplifying the difference between the outputs of the two coils 52 and 54, And a rectifying circuit 62 that rectifies the signal amplified by the circuit 60 and outputs the rectified signal as a detection signal 70.

 Next, the operation of the conductor detection device 50 will be described.

When a detection conductor 66 such as a metal is brought close to a magnetic field 64 generated from the detection coil 52, an eddy current 68 is generated in the detection conductor 66. Then, the impedance of the detection coil 52 changes due to the reverse magnetic flux generated by the eddy current 68, and the bridge circuit
56 becomes unbalanced, and the detection signal 70 is output via the amplifier circuit 60 and the rectifier circuit 62. The detection signal 70 is a relay (not shown)
[Problems to be Solved by the Invention] By the way, in such a conventional conductor detecting method and device, for example, when trying to detect a conductor existing inside a metal envelope, the metal envelope Will respond to
The conductor inside the metal envelope could not be detected.
This is because such a conventional conductor detection method and apparatus merely detects the presence or absence of a conductor, and does not detect a difference between two conductors.

Therefore, an object of the present invention is to provide a conductor detection method and apparatus capable of detecting a difference between two conductors and detecting a conductor present inside a metal envelope without being sensitive to the metal envelope. Is to do.

[Means for solving the problem]

In the conductor detection method according to the present invention, a reference metal envelope is brought close to a magnetic field generated from a reference coil, and the detection metal envelope is brought close to a magnetic field generated from a detection coil of the same standard as the reference coil. . The difference between the reference metal envelope and the detection metal envelope is detected by measuring the impedance difference between the detection coil and the reference coil.

Further, in the conductor detection device according to the present invention, first, a bridge circuit having a reference coil and a detection coil of the same standard as the reference coil, an oscillator that excites the bridge circuit, and an output signal of the bridge as a detection signal An output circuit for outputting the reference coil, wherein the reference coil is disposed so as to be able to approach a reference metal envelope generated from the coil, and the detection coil is the same as the reference metal envelope in a magnetic field generated from the coil. A standard metal envelope for detection is arranged so as to be accessible.

[Action]

In the conductor detection method according to the present invention, first, the reference metal envelope is brought close to the magnetic field generated from the reference coil, and the detection metal envelope is brought close to the magnetic field generated from the detection coil. At this time, if an impedance difference occurs between the reference coil and the detection coil, a difference between the reference metal envelope and the detection metal envelope is detected.

Further, in the conductor detection device according to the present invention, the bridge circuit is excited by the oscillator to generate a magnetic field from the reference coil and the detection coil. Then, the reference metal envelope is brought close to the magnetic field generated from the reference coil, and the detection metal envelope is brought close to the magnetic field generated from the detection coil. At this time, when an impedance difference occurs between the reference coil and the detection coil and an output signal is obtained from the bridge circuit, it is detected that there is a difference between the reference metal envelope and the detection metal envelope. Is done.

〔Example〕

FIG. 1 is a block diagram showing one embodiment of an apparatus based on the conductor detecting method according to the present invention.

The conductor detection device 10 includes a bridge circuit 16 having a reference coil 12 and a detection coil 14, an oscillator 18 for exciting the bridge circuit 16, and an output circuit 22 for outputting an output signal of the bridge circuit 16 as a detection signal 20. It is configured. The reference coil 12 is provided with a magnetic field 24 generated from the reference coil 12.
In addition, a reference metal envelope 26 as a reference conductor is disposed so as to be accessible. The detection coil 14 is a detection coil.
A detection metal envelope 30 as a detection conductor is arranged so as to be accessible to a magnetic field 28 generated from 14. In addition, the reference coil 12 and the detection coil 14
4, 28 are arranged so as not to affect each other.

The bridge circuit 16 is configured by connecting a series circuit of the reference coil 12 and the detection coil 14 and a series circuit of the resistor 32 and the resistor 34 to the oscillator 18 in parallel. A connection point between the reference coil 12 and the detection coil 14 and a connection point between the resistor 32 and the resistor 34 are connected to the input side of the output circuit 22. Further, the inductance and resistance of the reference coil 12 and the detection coil 14 and the resistances of the resistor 32 and the resistor 34 are set to values satisfying the equilibrium condition, respectively.

The output circuit 22 receives the output signal of the bridge circuit 16, performs processing such as amplification and rectification, and outputs the result as a detection signal 20.

In this embodiment, the oscillator 18 has a frequency of 2 kHz and an output voltage of 6 kHz.
V, the reference coil 12 and the detection coil 14 have an inductance of 1
00mH, resistance 100Ω, resistors 32 and 34 are set to 2kΩ.

 Next, the operation of the conductor detection device 10 will be described.

First, the bridge circuit 16 is excited by the oscillator 18 to generate magnetic fields 24 and 28 from the reference coil 12 and the detection coil 14.

Next, the reference metal envelope 26 is brought close to the magnetic field 24 generated from the reference coil 12 within about 10 cm, and the detection metal envelope 30 is moved to the magnetic field 28 generated from the detection coil 14 by about 10 cm.
Get closer within cm. Here, if the reference metal envelope 26 and the detection metal envelope 30 are the same, the bridge circuit 16 maintains an equilibrium state and the output voltage from the bridge circuit 16 is about 0V.
Becomes In other words, the conductor detection device 10 is insensitive to the metal envelope 30 for detection. In addition, even though the reference metal envelope 26 and the detection metal envelope 30 are the same, when the bridge circuit 16 becomes unbalanced, there is a difference in the conductors in the detection metal envelope 30. Is detected.

For example, as shown in the drawing, if a foreign substance 36 made of a conductor such as metal is mixed in the detection metal envelope 30, an impedance difference occurs between the reference coil 12 and the detection coil 14, so that the bridge circuit 16 As a result, the AC signal is output from the bridge circuit 16 and the detection signal 20 is obtained. At this time, the larger the difference between the conductors in the detection metal envelope 30,
The AC signal output from the bridge circuit 16 increases.
Thus, the entry of the foreign matter 36 is detected.

Further, according to the experiment of the inventor, the frequency of the oscillator 18 that can be detected satisfactorily varies depending on the detection conductor, but is about 2 to 3 kHz.

Further, the shapes, dimensions, and magnetic field strengths of the reference coil 12 and the detection coil 14 are determined according to the shape, dimensions, and material of the detection conductor.

The bridge circuit 16 includes a reference coil 12 and a detection coil.
14, and is not limited to the above configuration. For example, a series circuit of the reference coil 12 and the resistor 32 and a series circuit of the detection coil 14 and the resistor 34 are respectively connected to the oscillator 18 in parallel, and a connection point of the reference coil 12 and the resistor 32, The connection point between the coil 14 and the resistor 34 may be connected to the input side of the output circuit 22. Further, a resistor, a capacitor, a coil, and the like for adjustment may be added to the bridge circuit 16.

Further, in this embodiment, the conductor detection device 10 is used to detect the contamination of the foreign material 36. However, as in the next embodiment, the conductor existing in the reference metal envelope 26 is used as the detection metal envelope. It may be detected that it does not exist within 30.

FIG. 2 is a block diagram showing another embodiment of the conductor detecting method and apparatus according to the present invention. In this embodiment, the conductor detecting device 10 shown in FIG. 1 is used for a missing inspection of a cup ramen.

The conductor detection device 10 includes a reference unit 82 in which the reference coil 12 is stored in the housing 80, a detection unit 84 in which the detection coil 14 is stored in the housing 80, and a main unit 86 in which other components are stored. Divided into The housing 80 has an opening 88 for holding the reference coil 12 or the detection coil 14 in an exposed state.

The belt conveyor 90 has two belt wheels 92 and a mounting table 94.
By rotating the belt wheel 92 in the direction of arrow 97, the coupling ramen 98a, 9
It carries 8b and 98c.

On the mounting table 94, a detection hole 100 is formed.
The detection unit 84 is installed so that the detection coil 14 is exposed from 00.

The cup ramen 98a has a bowl shape with a maximum diameter of 150 mm and a height of 65 mm.The soup bag 102 is filled with powdered soup, put into a styrene foam container 106 together with dried noodles 104, and sealed with a lid 108. It was done. Soup bag
The cover 102 and the cover 108 are formed from a sheet in which a synthetic resin and an aluminum foil are laminated, and the thickness of the aluminum foil is 15 μm. The soup bag 102 has a rectangular shape, a length of 80 mm, a width of 65 mm, and a thickness of 5 mm when the powder soup is enclosed. The lid 108 is a disk-shaped metal envelope having a diameter of 150 mm.

 Next, the operation of the conductor detection device 10 will be described.

First, the reference cup ramen 98s is placed on the reference coil 12 of the reference portion 82. On the other hand, in the belt conveyor 90, a cup ramen 98 for detection, which is going to be inspected for missing parts, will be described.
a, 98b, 98c are sequentially carried onto the detection coil 14 of the detection unit 84. And cup ramen 98a is cup ramen 9
Since the soup bag 102 is contained as in the case of 8s, the bridge circuit 16 shown in FIG. 1 is balanced and its output voltage becomes about 0 mV. That is, the cup ramen 98a is determined to be good.

Further, unlike the cup ramen 98s, the cup ramen 98b does not contain the soup bag 102, so that the bridge circuit 16 shown in FIG. 1 becomes unbalanced, and its output voltage becomes about 1 mV. That is, the cup ramen 98b is determined to be defective because the soup bag 102 is missing.

At this time, the detection signal shown in FIG.
20 is output. Although not particularly shown, the detection signal 20 distinguishes a non-defective product from a non-defective product by means for driving a display lamp, a buzzer, or the like, stopping the rotation of the belt wheel 92, or removing a defective product. .

Even when the type of the cup ramen changes, it is only necessary to place the reference cup ramen on the reference coil 12 of the reference section 82, and a complicated operation such as adjustment is not required.

When nothing is placed on the reference coil 12 of the reference portion 82, the presence or absence of the detection conductor is detected as in the related art.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to the conductor detection method and apparatus according to the present invention, the reference metal enclosure is brought close to the magnetic field generated from the reference coil, and the detection metal enclosure is brought close to the magnetic field generated from the detection coil. The difference between the two metal envelopes can be detected, and the conductor present in the metal envelope can be detected.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an apparatus based on the conductor detection method according to the present invention, FIG. 2 is a block diagram showing another embodiment of the apparatus based on the conductor detection method according to the present invention, and FIG. FIG. 1 is a configuration diagram showing an apparatus based on a conventional conductor detection method. 10 Conductor detection device 12 Reference coil 14 Detection coil 16 Bridge circuit 18 Oscillator 20 Detection signal 22 Output circuit 24 Magnetic field generated from reference coil 26 Reference metal Enclosure (reference conductor) 28 Magnetic field generated from detection coil 30 Metal detection enclosure (detection conductor) 102, 108 Conductor 106 Container

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hirofumi Takahashi 1-34-5 Umegaoka, Setagaya-ku, Tokyo 2F Nagashima Building 2F Tomouchi Co., Ltd. (56) References JP-A-59-188587 (JP, A) JP-A Sho 59-231562 (JP, A) JP-A-48-7425 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01V 3/10

Claims (2)

(57) [Claims] A reference metal enclosure is brought close to a magnetic field generated from a reference coil, and a magnetic field generated from a detection coil having the same standard as the reference coil is detected by a magnetic field generated from a detection coil having the same standard as the reference metal enclosure. By detecting the impedance difference when the same envelope is applied to the detection coil and the reference coil by bringing the metal envelope close to the conductor, the conductor existing inside the metal envelope for detection is detected. Characteristic conductor detection method. A bridge circuit having a reference coil and a detection coil of the same standard as the reference coil, an oscillator for exciting the bridge circuit, and an output circuit for outputting an output signal of the bridge as a detection signal; The reference coil is arranged so that a reference metal envelope generated from the coil can be approached, and the detection coil is connected to a magnetic field generated from the coil by a detection metal envelope of the same standard as the reference metal envelope. The conductor detection device is arranged so as to be accessible.