JP7242443B2 - metal detector - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal detector, and more particularly to a metal detector that detects metal or metal components in an object to be inspected based on magnetic field fluctuations when the object to be inspected passes through an alternating magnetic field.

Conventionally, a transmission coil that generates an alternating magnetic field in an inspection area of an object to be inspected and a pair of differentially connected receiving coils that are arranged so as to be equally affected by the alternating magnetic field are moved in the inspection area. There is known a metal detector that extracts the fluctuation of the magnetic field due to the influence of the object to be inspected as an unbalanced signal of the induced voltage of a pair of receiving coils, and performs quadrature detection processing to extract a metal detection signal from the unbalanced signal. there is

In this type of metal detection device, the display for displaying the presence or absence of metal detection is composed of a plurality of display elements that sequentially light up in accordance with the metal detection level for indicating the presence or absence of metal detection. (See Patent Document 1, for example).

In addition, by generating information data of a product list including the estimated detection sensitivity by the control calculation unit for multiple types of metal contaminants and displaying the product list along with the estimated detection sensitivity, operations such as mode selection can be executed without changing the display. There is known a device that does this (see, for example, Patent Document 2).

Japanese Utility Model Laid-Open No. 57-192485 JP 2005-345434 A

However, the conventional metal detectors described above only show that the detection sensitivity differs depending on whether the metal is magnetic or non-magnetic. It cannot be said that it is possible to clearly identify and display whether it is a metal or a non-magnetic metal, that is, the type of metal with different magnetism.

Therefore, depending on the user, there is a burden of determining the type of metal while considering the detection level display and other inspection conditions. There was a problem that it was not possible to judge

SUMMARY OF THE INVENTION In order to solve the above-described conventional problems, the present invention provides a metal detector capable of accurately and automatically determining whether a metal passing through an inspection area is a magnetic metal or a non-magnetic metal, and identifying and displaying the metal. With the goal.

(1) In order to achieve the above object, the metal detection apparatus of the present invention comprises a magnetic field generator for generating an AC magnetic field based on a reference signal in an inspection area through which an object to be inspected passes; a magnetic field detector for detecting fluctuations in the alternating magnetic field in the region and outputting a magnetic field fluctuation signal; a detection circuit unit for executing a detection process for detecting a second fluctuation component on the side and a second fluctuation component in two detection phases orthogonal to each other; and the first fluctuation component and the second fluctuation detected by the detection circuit unit. and a determination unit that performs determination processing for detecting metals mixed in the object to be inspected based on the components, wherein the determination unit includes: Sample signal phase data obtained in advance from the magnetic field fluctuation signals detected by passing various metal samples, and inspected object signals obtained from the magnetic field fluctuation signals detected by passing the inspected objects mixed with metal. phase determination means for determining a difference between the phase data and the phase data; and type display means for displaying the metal mixed in the object to be inspected in a different color tone for each type of different magnetism based on the determination result of the phase determination means. characterized by having

With this configuration, it is possible to determine the difference in phase from the sample signal phase data for a plurality of types of metal samples for the object signal phase data that is greatly affected by the metal mixed in the object, and based on the determination result, The metal mixed in the object to be inspected is displayed in different color tones for different types of magnetism. Therefore, it is possible to accurately and automatically determine whether the metal mixed in the object to be inspected is a magnetic metal or a non-magnetic metal, and to identify and display it.

(2) In the metal detection apparatus of the present invention, the type display means specifies a plurality of phase regions generated by a mutual phase difference occurring in an orthogonal coordinate system corresponding to the two detection phases for the plurality of types of metal samples. It is possible to adopt a configuration in which a scale display in which the metals are aligned in different directions and displayed in different tones, and an identification display in which the phase of the metal currently being detected on the scale display is displayed in an identifiable manner.

In this case, multiple types of metal samples are displayed on a scale with different colors for each type with different magnetism, and the phase of the metal currently being detected is displayed on the scale display in an identifiable manner. and metal types can be clearly identified and displayed.

(3) In the metal detecting device of the present invention, the type display means may display the scale display in the form of a bar-shaped scale extending in the predetermined direction.

In this way, the presence or absence of metal magnetism and the type of metal can be identified and displayed more clearly.

(4) In the metal detecting device of the present invention, the different types of magnetism may include at least a magnetic metal type and a non-magnetic metal type.

By doing so, the presence or absence of magnetism of the metal can be identified and displayed more clearly.

According to the present invention, it is possible to provide a metal detector capable of accurately and automatically determining whether a metal passing through an inspection area is magnetic or non-magnetic, and displaying the identification.

1 is a schematic block configuration diagram of a metal detector according to a first embodiment of the present invention; FIG. FIG. 2 is a schematic perspective view showing an arrangement form of transmission coils and reception coils in the detection head in the metal detection device according to the first embodiment of the present invention; FIG. 4 is an explanatory diagram of the principle of differential detection of magnetic field fluctuations when passing through metal in the metal detector according to the first embodiment of the present invention. FIG. 4 is an explanatory diagram of quadrature detection of differential detection signals in the metal detection device according to the first embodiment of the present invention; FIG. 4 is a graph showing the distribution form of quadrature detection signal data on the orthogonal coordinate plane in the metal detection device according to the first embodiment of the present invention in a Lissajous figure, in which the horizontal axis represents the signal component level in phase with the reference signal, and the vertical axis represents the reference signal. It shows the signal component level in phase orthogonal to the signal. FIG. 2 is a schematic explanatory diagram of a determination map illustrating determination conditions for determining the type of mixed metal from the distribution of quadrature detection signal data on an orthogonal coordinate plane in the metal detection device according to the first embodiment of the present invention; FIG. 4 is an explanatory diagram of a memory that readable and stores metal type determination conditions for each inspection condition provided in the control unit of the metal detection device according to the first embodiment of the present invention; 4 is a flowchart showing a procedure for storing metal type determination conditions for each inspection condition in a memory of a control unit of the metal detection device according to the first embodiment of the present invention; 4 is a flow chart showing an outline procedure of processing for determining the type of a metal sample during sample inspection in the metal detection device according to the first embodiment of the present invention; FIG. 4 is a schematic diagram of a display example of a display device in the metal detection device according to the first embodiment of the present invention, and illustrates a case where metal types with different magnetism are displayed in gradation in colors of the types. FIG. 10 is a schematic diagram of a display example of each indicator in the metal detection device according to the second embodiment of the present invention, showing a scale display curved in a substantially elliptical shape. (a) is a schematic diagram of a display example of a display device in a metal detection device according to a third embodiment of the present invention, showing a bar-shaped monochromatic scale display; It is a schematic diagram of one display example of the indicator in the metal detection device according to the fourth embodiment, showing bar-shaped multicolor scale display.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated, referring drawings.

(First embodiment)
1 to 10 are diagrams showing a schematic configuration of a metal detection device according to a first embodiment of the present invention.

First, its configuration will be described.

As shown in FIGS. 1 and 2, the metal detector 10 of the present embodiment is provided with a conveyor 12 for conveying a workpiece W to be inspected, and an inspection head 14 positioned in the middle of the conveyor 12. ing.

The workpiece W is, for example, a mass-produced food product wrapped in a packaging material. It's fine, it can be frozen. Of course, the article to be the work W is not limited to food.

The conveyor 12 is composed of, for example, a belt conveyor having loop-shaped belts and rollers (not shown), and can convey the work W in a predetermined direction through an opening 14 a in the inspection head 14 .

The inspection head 14 can generate an alternating magnetic field in an inspection area Z corresponding to a predetermined length of workpiece transfer section of the conveyor 12, and detects variations in the magnetic field in the inspection area Z accompanying passage of the workpiece W. Metal in the work W (contaminant foreign matter or a part of the pre-enclosed product) or non-metallic foreign matter (metal or foreign matter containing metal components, in the case of missing item detection (It may be a component instead of a foreign object).

At the entrance side of the inspection area Z (on the upstream side in the transport direction), for example, an optical article detection sensor 15 for detecting the entry of the workpiece W into the inspection area Z is installed. In addition, an operation input unit 16 for inputting operations by the user, and a display 17 for performing display for operation, operation status display, abnormality notification, etc. are provided on the upper front side of the metal detector 10. It is

Specifically, the metal detector 10 includes a signal generator 21 and a transmission coil 22 that cause the inspection head 14 to generate an alternating magnetic field, and one and the other receiving coils 23a and 23b that cause the inspection head 14 to detect variations in the alternating magnetic field. , a detection unit 24 that performs quadrature detection processing on the detection signal of the inspection head 14, A/D converters 27a and 27b that A/D converts the detection output signal from the detection unit 24, and detection after the A/D conversion. and a control unit 30 for executing a predetermined control program capable of metal detection based on data.

The signal generator 21 generates an AC transmission signal of a predetermined frequency, and current-drives the transmission coil 22 via a current amplifier (not shown). The transmission coil 22 is arranged near the conveying path of the conveyor 12, and when excited by the current drive from the signal generator 21, an alternating magnetic field (alternating magnetic field) of a predetermined strength corresponding to the frequency of the transmission signal is applied to the inspection area Z. It is designed to be generated inside. The transmission coil 22 and the signal generator 21 constitute a magnetic field generator.

More specifically, as shown in FIG. 2, the transmit coil 22 is positioned within the test head 14 to surround the opening 14a, and one and the other receive coils 23a, 23b are positioned within the test head 14 opening. 14a and arranged so as to have substantially the same center axis in front and rear of the transmission coil 22 in the work transfer direction.

Each of the receiving coils 23a and 23b is composed of at least a pair of coils arranged so that the magnetic flux from the transmitting coil 22 interlinks substantially equally and connected in opposite phases to each other. It is connected to the detection unit 24 on the side. These receiving coils 23a and 23b constitute a differential detector 23 (magnetic field detection section) that cooperates with the transmitting coil 22 to detect variations in the magnetic field in the inspection area. The frequency of the AC magnetic field generated by the transmission coil 22 is variably set by a control unit 30, which will be described later, and the differential detector 23 can detect variations in the AC magnetic field of each set frequency. .

Specifically, when an alternating magnetic field is generated in the inspection area Z, voltages are induced in the receiving coils 23a and 23b, respectively, but only the alternating magnetic field from the transmitting coil 22 is connected in reverse phase. The voltage outputs of the receiving coils 23a and 23b are equally balanced, and the difference between the induced voltages of the receiving coils 23a and 23b (the output of the differential detector 23) is zero. Therefore, for example, the other ends of the receiving coils 23a and 23b are coupled via, for example, a balance adjustment variable resistor (not shown), and the middle point of the variable resistor is connected to the detector 24. FIG.

A magnetic metal passing through the magnetic field of the inspection area Z attracts more magnetic flux in proportion to the magnitude of the magnetic flux density, while a non-magnetic metal passing through the magnetic field experiences a change in magnetic flux density due to its movement. Eddy currents are generated in a counteracting direction, and Joule heat is consumed.

Therefore, when some magnetic metal mixed in the product on the conveyor 12 passes through the generated magnetic field of the inspection area Z, the position of the metal attracting the magnetic flux is determined as shown in FIGS. , the magnitude relationship between the induced voltages Va and Vb of the receiving coils 23a and 23b changes, and the output balance between the receiving coils 23a and 23b is disturbed. Also, even when only non-magnetic products pass through the magnetic field generated by the transmission coil 22, due to the influence of the contained components, moisture, packaging materials, etc., the reception is not as pronounced as when the product contains metal. The output balance between the coils 23a and 23b is disturbed.

When the output of the receiving coils 23a and 23b becomes unbalanced due to the movement of the product on the conveyor 12, the receiving coils 23a and 23b generate a differential detection signal Sd (magnetic field fluctuation) corresponding to the change in the magnetic field. signal). The differential detection signal Sd includes a high-frequency signal component having the frequency of the transmission signal corresponding to the alternating magnetic field from the transmission coil 22 side, and a low-frequency signal component whose amplitude and phase change according to the movement of the work W. It becomes a superimposed modulated signal form, which can be represented by a signal waveform as shown in FIG. 4, for example.

As shown in FIG. 1, the detection section 24 constitutes a detection circuit section comprising a pair of mixers 24a and 24b, bandpass filters 25a and 25b, and phase shifters 26a and 26b. A differential detection signal Sd from the differential detector 23 is input to each.

The mixers 24a and 24b are respectively connected to phase shifters 26a and 26b for shifting the phase of the input signal by a set phase shift amount. The signal is phase-shifted by a predetermined phase-shift amount that is variably set so as to increase the detection sensitivity, and is supplied to the mixer 24a. In addition, the phase shifter 26b further shifts the phase of the signal generated by the phase shifter 26a by 90 degrees, so that the high frequency signal component of the differential detection signal Sd induced and output from the differential detector 23 is to generate a high frequency signal with a phase difference of 90 degrees and supply it to the mixer 24b.

The mixer 24a combines the high-frequency signal from the phase shifter 26a and the differential detection signal Sd from the differential detector 23 and outputs the combined signal to the bandpass filter 25a. Similarly, the mixer 24b synthesizes the high-frequency signal from the phase shifter 26b and the differential detection signal Sd from the differential detector 23, and outputs the result to the bandpass filter 25b.

The mixing of the inputs by the mixers 24a and 24b here differs depending on the amount of phase shift. , the detection signal Rx of the first fluctuation component, which consumes Joule heat and causes a change in the external magnetic field, the larger the change in the magnetic flux density, the larger the influence of the non-magnetic metal, and the moment when the magnetic flux density itself becomes almost maximum (the amplitude of the magnetic field waveform is maximum; phase 90 degrees) side, the larger the magnetic flux density, the more magnetic flux is attracted to cause the change in the external magnetic field. can.

The band-pass filters 25a and 25b extract detection signals of low-frequency signal components that change corresponding to the movement of the workpiece W from both the detection signals Rx and Ry synthesized by the mixers 24a and 24b, and also extract detection signals of high-frequency components. It has filter characteristics to remove noise.

As shown in FIG. 4, the low-frequency component detection signals X and Y output from the bandpass filters 25a and 25b are envelope waveforms connecting instantaneous values at predetermined phase positions in the waveform of the differential detection signal Sd. and an envelope waveform connecting instantaneous values shifted in phase by 1/4 of the transmission signal period τ from the predetermined phase position, that is, by 90 degrees.

The detection signals X and Y output from both bandpass filters 25a and 25b are converted from analog signals to detection data Dx and Dy, which are digital signals, respectively by A/D converters 27a and 27b. are taken into the control unit 30 as detection data Dx and Dy associated with the article detection signal from.

The control unit 30 has a microcomputer configuration including, for example, a CPU, a RAM, a ROM and an I/O interface, and executes a control program stored in the ROM while exchanging data with the RAM. Various signals such as detection data Dx and Dy received via the O interface are processed. The control unit 30 may also include a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), or the like that performs digital signal processing.

By executing the above-described control program, the control unit 30 has a setting unit 31, a first memory unit 32 for storing inspection data, a second memory unit for phase determination, as shown in the functional block diagram of FIG. 33, a third memory unit 34 for storing inspection conditions, a phase correction unit 35, and a determination unit 36.

The setting unit 31 has a function of manually initializing various parameters required for inspection in accordance with an instruction input from the operation input unit 16, and a function of setting non-defective samples of the work W, metal samples Tp1, Tp2 such as test pieces, etc., into a magnetic field. It has a function (auto setting mode) of semi-automatically initializing the parameters necessary for the inspection by passing it through. Further, the setting unit 31 can switch between a normal metal detection mode and a setting/confirmation mode, which will be described later, according to a selection operation input to the operation input unit 16 .

This setting unit 31, for example, sets the size (e.g., length) and conveying speed of the work W of each product type, the frequency of the signal generated by the signal generator 21, the phase correction amount Δθ by the phase shifter 26a, the pass through the bandpass filters 25a and 25b It is a setting means for manually inputting some of various setting parameters related to the operation of the metal detecting device 10 such as the band (frequency band) for each type of work W and automatically setting the others.

The length of the workpiece W and the transport speed are conditions for determining the time and interval of the detection data Dx and Dy, the passbands of the bandpass filters 25a and 25b, and the like. The frequency of the signal generated by the signal generator 21 is a parameter that can be selected according to the type and size of the metal to be detected, the material of the constituent materials of the work W (contents, packaging materials, etc.). Furthermore, as is clear from the fact that the detection data Dx is specified by the instantaneous value at the predetermined phase position corresponding to the phase shift amount of the phase shifter 26a, the waveform amplitudes of the detection data Dx and Dy are determined by the phase of the phase shifter 26a. It differs depending on the correction amount Δθ. That is, the phase shift amount of the phase shifter 26a is a parameter that determines the detection sensitivity of the metal mixed in the workpiece W. As shown in FIG.

The phase correction unit 35 corrects a series of detection data Dx and Dy of the low-frequency signal components taken in from the A/D converters 27a and 27b each time each workpiece W to be inspected passes through the inspection area Z, by a predetermined number of samplings. Based on the obtained signal data, as shown in FIG. 5, on the XY plane, the horizontal axis is the phase 0° (in-phase) side at the time of detection, and the vertical axis is the phase 90° (quadrature phase) side. , a Lissajous figure can be created as a scatter diagram in which the values of the detection data Dx and Dy are orthogonal coordinate components.

The phase correction unit 35 uses the center phase θd of distribution of the detection data of the magnetic field fluctuation component due to the product influence of the work W in the Lissajous figure shown in FIG. (corresponding to the difference in inclination angle of the regression line in the scatter diagram) can be calculated to correct the detection phase.

In this case, if the work W contains a metal (metal foreign matter or metal component in the product), as shown in FIGS. Detected data Dx, Dy (hereinafter referred to as product ) are distributed in the vicinity of the reference phase I, and the detection data Dx and Dy when metal is passed through (hereinafter referred to as metal influence signals) are distributed on the quadrature phase Q side. The in-phase side and the quadrature-phase side referred to in the present invention refer to the relative phase relationship between the two detection signals X and Y. As shown in FIG. If the detection signals X and Y are envelope-shaped that connect the specific phase positions (on the right side of the figure), it means that the detection signal Y has a larger phase difference than the detection signal X with respect to the starting point. In addition, on the low amplitude side of the phase 0° or 180° of the AC magnetic field corresponding to the reference signal, the amount of change in the magnetic flux density of the AC magnetic field increases, and on the high amplitude side of the phase 90° or 270° magnetic flux density increases.

The phase correction unit 35 adjusts the sensitivity so that the amplitude level on the in-phase I side, which is greatly influenced by the product, becomes the minimum level in the quadrature phase Q, which is the phase for determining the presence or absence of metal, and the amplitude level appears large on the quadrature phase Q side, where the influence of metal is large. It is designed to be set.

The determination unit 36 compares the amplitudes Lg and Ln of the detection data of the product effect and the metal effect in the metal presence/absence determination phase (quadrature phase Q) on the IQ plane, and the amplitude ratio (Ln/Lg) has a first determination unit 36a (metal presence/absence determination means) that executes determination processing of metal presence/absence in the workpiece W depending on whether or not the value exceeds a predetermined limit value.

By the way, in FIG. 5, the shape of the metal influence signal scatter diagram (Lissajous figure Hn) is relatively thin with respect to the shape of the product influence signal scatter diagram (Lissajous figure Hg) of the work W. The detection phase (θn in the figure) is substantially orthogonal to the detection phase (θd in the figure) of the product influence signal. (the shape of the Lissajous figure) varies depending on the material and size of the metal or test piece, and the inclination of the figure is determined by the above-mentioned predetermined phase position (the above-mentioned phase correction amount Δθ).

The Lissajous figure Hn of the metal influence signal shown in FIG. 5 schematically illustrates the case where the material is a non-magnetic metal. The phase angle varies depending on the amount and other types of metals (e.g., aluminum (Al), brass, etc.), or the distinction between non-metals and metal-containing composites, etc., and the size of the metal ( For example, the amplitude tends to vary depending on the diameter.

Therefore, in the present embodiment, in the first determination unit 36a of the control unit 30, the ratio of the amplitude of the magnetic field fluctuation component due to the metal effect to the product effect (Ln/Lg in FIG. 5) is the maximum. In addition to the sensitivity-prioritized processing, the second determination unit 36b and the third determination unit 36c perform processing for determining the type of metal separately from the sensitivity-prioritized processing. It's like

In FIG. 6, the horizontal axis is the reference phase I whose phase is adjusted so as to be within the range of the variation level of the detection signal due to noise and vibration, and the vertical axis is the quadrature phase axis Q that is orthogonal to the reference phase IQ. When the results of calculating the detected phase angles θn of the peaks Ps of the Lissajous figures Hn of the metal influence signals for the types and sizes of a plurality of metals (objects to be detected) are plotted on a plane, the detected phase angles θn differ from each other. FIG. 10 is an explanatory diagram of a determination map (type determination condition) for classifying a plurality of different type groups by their phase angle distribution ranges;

In FIG. 6, "Fe" exemplifies the distribution range when the metal is iron or other magnetic metal, and depending on the type and size (diameter Φ) of the magnetic metal, for example The boundary line B1, which curves toward the increasing phase angle side, is the upper limit of the phase angle of the metals of the type group, such that the phase angle increases as the diameter of the metal increases away from the boundary line B1.

In FIG. 6, "SUS" includes, for example, ferritic stainless steel near the boundary line B1, austenitic stainless steel near the boundary line B2, and many other stainless steels (martensitic, etc.). This can contribute to the determination of the type of metal used as the material. Also in this case, the phase angle increases as the metal diameter increases away from the center of the IQ plane, and the boundary line B2 is also curved toward the phase angle increasing side. That is, the boundary line B2 shows a tendency that the detection phases of the adjacent type groups are not proportional to the size (diameter Φ) of the metal, similarly to the boundary line B1.

In FIG. 6, Non-Fe exemplifies the distribution range in the case of another type group consisting of aluminum, brass and other non-ferrous metals, highly corrosion-resistant special metals, composite materials, etc., and the metal type or size ( The phase angle differs depending on the diameter Φ), and the range of the variation level of the detection signal due to noise and vibration near the phase angle that is inverted (180° difference) with respect to the reference phase I is the upper limit of the phase angle of the metal of that type group. It's becoming

Thereafter, when the predetermined phase position when extracting the detection signals X and Y from the differential detection signal Sd is on the higher phase angle side, Fe, SUS, and Non-Fe are similarly arranged in this order with the boundary lines B1 and B2 interposed therebetween. The distribution for each type group is divided.

A type determination map as shown in FIG. 6 is stored as type determination condition data in the second memory unit 33 for phase determination. Then, it is determined which of the distribution regions Fe, SUS, and Non-Fe for each of the plurality of type groups in FIG. there is Here, the type determination condition data stored in the second memory unit 33 and used in the second determination unit 36b is detected when various types of metal samples out of a plurality of types of metal samples are passed through the inspection head 14. This is sample signal phase data for each type obtained in advance using the magnetic field fluctuation signal obtained.

A second determination unit 36b of the determination unit 36 determines, when various metal samples Tp1, Tp2, etc. among a plurality of types of metal test pieces and other metal samples pass through the inspection area Z, The phase θn of the Lissajous figure Hn of the metal influence signal of the low frequency component generated in the orthogonal coordinate system (XY coordinate system) corresponding to the orthogonal detection phase with the fluctuation of the AC magnetic field is determined. Further, when the workpiece W mixed with metal passes through the inspection head 14, the second determination unit 36b converts the phase data (inspected object signal phase data) obtained based on the detected magnetic field fluctuation signal into the sample signal described above. It is phase determination means for determining the phase of the work W and the phase of the metal mixed in the work W by comparing with the phase data and determining the difference between the two data.

A third determination unit 36c of the determination unit 36 selects a group of magnetic metals such as iron (Fig. 6 (indicated as Fe in FIG. 6), non-magnetic metal group such as stainless steel group (indicated as SUS in FIG. 6), or aluminum, brass and other types (indicated as Non-Fe in FIG. 6) display) is detected, and outputs the result to the display device 17 together with the determination type. The third determination section 36c serves as metal type determination means for determining the type of metal passing through the inspection area Z based on the determination result of the second determination section 36b, which is the phase determination means.

FIG. 6 shows that the distribution of the detected phase angles θn of the metals of each type group increases as it moves away from the center point of the IQ orthogonal coordinate plane, within the range of the distribution accuracies θa, θb, and θc of each type group. means trend. However, the conditions for type determination are not limited to those shown in FIG. If you want to set the distribution range, instead of dividing the distribution range by boundary lines, you can set multiple independent distribution areas specified in the distribution range of a specific type and determine whether it belongs to any of them. good.

FIG. 7 shows an inspection condition storage for storing inspection conditions and transmission output levels under these conditions for executing judgment for each type of metal as shown in FIG. 3 is a functional explanatory diagram of a third memory unit 34; FIG.

As shown in FIG. 7, the third memory unit 34 stores each transmission signal from a predetermined transmission frequency 1 and transmission output (level) 1 to a transmission frequency n and a transmission output n obtained by sequentially changing at least one of the values. Regarding the frequency and the transmission output, the detection unit 24 detects the magnetic field fluctuation signal Sd in the inspection area Z accompanying the conveyance and passage of the workpiece W, and the frequency band, phase and amplitude, which are the passband when performing band-pass filter processing, Data set from frequency band 1, phase 1 and amplitude 1 to frequency band n, phase n and amplitude n are stored and saved. The data set in this way are obtained in advance for each type from the magnetic field fluctuation signals detected when various metal samples among a plurality of types of metal samples are passed through the inspection head 14 for each transmission frequency and transmission power. It contains the sample signal phase data and the sample signal amplitude data referred to in the present invention.

Each transmission condition from transmission frequency 1 and transmission output 1 to transmission frequency n and transmission output n, and the stepwise setting of frequency band, phase and amplitude when filtering detection signals Rx and Ry can be set, for example, in a plurality of ways. It is effective to prepare a plurality of metal samples of the same type with different sizes for each type of metal sample and to set suitable inspection conditions for each.

Based on the inspection conditions stored in the third memory unit 34, the third determination unit 36c of the determination unit 36 determines the inspection area for a plurality of metal samples of the same type having different sizes for each type of the plurality of metal samples. In addition to determining the type of metal passing through Z, the amplitude of the metal effect signal can also be determined. Therefore, the third determination unit 36c cooperates with the third memory unit 34 to also determine the amplitude of the metal influence signal for a plurality of metal samples of the same type having different sizes for each type of metal samples. It can function as amplitude determination means.

As described above, the metal detector 10 of this embodiment includes the signal generator 21 and the transmission coil 22 as magnetic field generators for generating an AC magnetic field based on the reference signal in the inspection area Z through which the work W passes, and the work W A differential detector 23 for detecting fluctuations in the alternating magnetic field in the inspection area Z due to the passage of the magnetic field fluctuation signal Sd and outputting a magnetic field fluctuation signal Sd; A detection unit 24 that performs a process of detecting X and a second variation component signal Y on the quadrature phase side with respect to the reference signal with two detection phases that are orthogonal to each other, and detection signals X and Y from the detection unit 24. and a determination unit 36 having a first determination unit 36a that executes a metal presence/absence determination process for detecting metal mixed in the work W based on the above.

In addition to the first determination unit 36a for detecting the metal mixed in the work W with high sensitivity, the determination unit 36 detects the mixed metal in the work W or various types of metal samples out of a plurality of types. When the alternating magnetic field in the inspection area Z fluctuates, the phase θn of the metal effect detection data generated in the orthogonal coordinate system corresponding to the quadrature detection phase accompanying the fluctuation is compared with the sample signal phase data for each type to determine the difference. and a third determination unit 36c as metal type determination means for determining the type of metal passing through the inspection area Z based on the determination result. there is

Further, the third determination unit 36c of the determination unit 36 functions as an amplitude determination means for determining the difference in the amplitude of the metal influence signal for a plurality of metal samples of the same type with different sizes for each type of the plurality of types of metal samples. , and the type and size of the metal passing through the inspection area Z can be determined based on the amplitude determination result.

In addition, the third determination unit 36c as a metal type determination means approximates any type of metal sample among a plurality of types based on data including not only the phase θn but also the amplitude of the metal influence signal generated in the orthogonal coordinate system. and whether it is different from the others, and which size of the metal sample is approximated and different from the others among a plurality of metal samples of the same type, are determined by using a plurality of type groups (Fe, SUS, Non-Fe ) is determined based on the information on the boundary lines B1 and B2 of the distribution area.

Then, the second determination unit 36b of the determination unit 36 determines when various metal samples pass through the inspection region Z for each of a plurality of frequency bands set for the frequency of the reference signal or the detection signal of the differential detector 23. The judgment conditions for judging the phase θn of the metal influence signal generated in the orthogonal coordinate system (e.g., the judgment map shown in FIG. 6 or the calculation formula of the boundary lines B1 and B2 for judgment, etc.) are set by the sample signal phase data and the sample The data is stored in the second memory unit 33 and the third memory unit 34 as signal amplitude data and the like, and the type of metal passing through the inspection area Z is determined based on the determination conditions.

In the metal detection device 10 of the present embodiment, the control unit 30 further accumulates the determination results of the determination unit 36 to obtain statistics of the inspection results of the work W that has passed through the inspection area Z and the history of the inspection and metal detection results. It also has a statistics/history processing unit 37 that can associate and record type information corresponding to the history information while acquiring it by a known method.

Next, the operation and effects of the metal detector 10 having the above configuration will be described.

[When setting and confirming operation]
When setting and confirming the operation of the metal detector 10, the user presses the menu key of the operation input unit 16 to display a menu screen having selection items such as auto setting, detection sensitivity (level) change, item effect display, and statistics menu. (details not shown) is displayed. First, for example, an auto setting is selected, and before actually executing metal detection, a test inspection/inspection is performed by passing a non-defective sample of the work W and metal samples Tp1 and Tp2 of a plurality of types of foreign matter through the inspection head 14. By performing measurement (hereinafter, also referred to as sample inspection), initial settings necessary for the operation of each part constituting the metal detector 10 are performed. The sample inspection is performed not only when registering the product type to be inspected, but also when confirming the operation based on the registered information. Such a sample test may partially or wholly use a test variation component corresponding to a test piece influence signal described in Japanese Unexamined Patent Application Publication No. 2018-200197, for example.

As shown in FIGS. 7 and 8, for each of the transmission conditions (transmission frequency and transmission power) 1 to n to be stored in the third memory unit 34 for storing inspection conditions, information of "frequency band, phase, amplitude" is stored. When setting, first, for the first inspection condition/output 1, the transmission condition is read (steps S11 and S12), and the transmission frequency setting and the A transmission output is set (steps S13 and S14).

Next, an alternating magnetic field is generated in the inspection area Z of the metal detection device 10 (step S15), and the work W is conveyed by the conveyor so as to pass through the inspection area Z (step S16). Based on the magnetic field fluctuation signal Sd output from 23, the signal processing system from the detection unit 24 to the control unit 30 is caused to execute received signal processing (step S17). Then, from the Lissajous figure Hn of the metal influence signal in the orthogonal coordinate system, the amplitude Ln and phase θn of the magnetic field variation component are calculated and stored in the third memory unit 34 for storing inspection conditions (step S18).

Next, it is determined whether or not the transmission condition (transmission frequency and transmission output level) n has been reached (k=n) (step S18). ), until the transmission condition n is reached, the test inspection/measurement with a series of processing steps S11 to S19 is repeated, and the work of setting the stored information in the third memory section 34 for storing the inspection condition is executed.

During such setting work, the control unit 30 successively determines the status of product registration, and if automatic setting is not yet completed, a symbol indicating that setting is not completed is displayed as an operation mode display symbol, and product registration is completed. Then, a display prompting a required setting operation is made, such as changing to a different mode display symbol.

In this embodiment, the metal samples used are a magnetic metal iron-based (Fe) test piece, a non-magnetic metal stainless steel (SUS) test piece, and a non-ferrous (Non-Fe) test piece. In the case of multiple types of metal samples Tp1, Tp2, etc., such as pieces, the test conditions can be set using those test pieces in an arbitrary order.

Further, when sample inspection using a plurality of predetermined types of test pieces is requested in operation confirmation of the metal detection device 10, the determination unit 36 determines the type of each metal sample for the plurality of types of metal used in the sample inspection. Since the determination is possible, only by passing only the same kind of metal sample, for example, a magnetic metal sample through the inspection head 14, the operation can be performed without sample inspection using a different kind of metal sample such as a non-magnetic metal. It is possible to prevent work omissions and mistakes such as ending the confirmation work.

Furthermore, during the auto setting, for example, among multiple types of test pieces, a magnetic metal test piece is first used to set rough detection conditions, and then a non-magnetic metal test piece is used to determine the presence or absence of magnetism. If a procedure for setting detection conditions that can reliably detect metals is determined in advance, even if the procedure is incorrect, the control unit 30 can detect suitable metals based on the inspection data for each type. Detection conditions can be set.

[Normal operation mode]
During normal operation of the metal detector 10, the screen during operation is displayed on the display 17, although the details are not shown. During this normal operation, for example, the product number, product name, characters such as OK (good product / acceptable) / NG (defective product / rejection) which is the judgment result, the total number of inspections of the work W, the number of NG products counted, operation or A character or the like indicating that the work W is stopped is displayed, and when it is detected that metal is mixed into the workpiece W, the character NG is displayed along with the type of the detected metal, which can be used to determine the presence or absence of magnetism, such as Fe, SUS, or the like. A display output such as Non-Fe is made.

The process of determining the metal type and size is carried out according to the procedure shown in FIG.

First, after reading and inputting result information of sample inspection using test pieces of multiple types from the third memory unit 34 for storing inspection conditions (step S21), amplitude (i) corresponding to each inspection condition (amplitude 1 to amplitude n) and phase (i) (from phase 1 to phase n) are read (step S22).

Next, from the second memory unit 33 for phase determination, determination information on the types and sizes of magnetic, non-magnetic, and other metals, that is, a map (type determination condition ) or calculation formulas for a plurality of boundary lines B1 and B2 (step S23). It is determined in which amplitude region the amplitude Ls of the peak Ps belongs to the distribution range and in which size the amplitude Ls of the peak Ps is located, and stored in the first memory unit 32 for storing inspection data and the statistics/history processing unit 37 (step S24). ).

Next, the presence or absence of a sorting command request to the sorting mechanism 43, an inspection history display request, an inspection result statistical display request, or a display output request for the type and size of the detected metal is checked (step S25). After executing the output process (steps S26, S27, S28, S29), the current process ends.

FIG. 10 shows an example of display on the display 17 accompanying output processing by the control unit.

As shown in the figure, in the display screen 171 of the display 17, from the top to the bottom, there are an operation mode display area 172, an operation state display area 173, and a magnetic field for the test piece being transported or the NG sample. A type display scale area 174 for displaying different metal types and a metal inspection result display area 175 are arranged.

The operation mode display area 172 displays that the device is "driving", that the operation mode is, for example, "confirmation mode", the date and time, the type of storage, and the like. The operating state display area 173 displays the current operating state, for example, that component analysis is being performed in a "confirmation mode" using a test piece.

The type display scale area 174 is a type display means for displaying the type of the detected metal, for example, the type of the test piece currently being inspected. and 174d form a scale display that aligns in a predetermined direction and displays in different tones a plurality of phase regions generated by mutual phase differences occurring in the orthogonal coordinate system corresponding to the detection phases for a plurality of metal samples.

Specifically, the plurality of type display areas 174a to 174d are, for example, one of the "Noise" area 174a, the "magnetic material" area 174b, the "non-magnetic material" area 174c, and the "OVF (overflow)" area 174d. is displayed in association with

Here, the "Noise" region 174a corresponds to the phase angle distribution region due to the influence of noise, workpiece or vibration in FIG. there is The "magnetic material" region 174b corresponds to the distribution region of the phase angle of the peak of the Lissajous figure under the influence of magnetic metal such as iron (Fe).

The “non-magnetic” region 174c corresponds to the distribution region of the phase angle θn of the peak Pn of the Lissajous figure Hn under the influence of non-magnetic metal such as stainless steel (SUS). It also includes the distribution region of the phase angle of the peak of the Lissajous figure due to the influence of non-ferrous metals such as aluminum (Al), etc. .

The "OVF" region 174d has an excessively large phase angle that is not effective in detecting the metal effect on the magnetic field of the inspection region Z within the phase angle range of every 180 degrees in which the magnitude of the metal effect can be evaluated from the detection data Dx and Dy. overflow area.

A pointer 174f is displayed in a "non-magnetic material" area 174c in FIG. are). The pointer 174f is displayed so as to be movable to the left and right in FIG. The type of detected metal or test piece, the presence or absence of magnetism, and the degree of magnetism can be identifiably displayed depending on which of the display positions 174a, 174b, 174c, or 174d is displayed and the difference in color tone. It's like That is, the pointer 174f can identify and display the phase of the metal currently being detected in the type display areas 174a to 174d of the type display scale area 174. FIG.

The metal inspection result display area 175 includes, for example, an ML1 display portion 175a that displays the amplitude level of magnetic field fluctuations influenced by magnetic metals in comparison with the judgment limit value, and an ML1 display portion 175a that displays the amplitude levels of magnetic field fluctuations influenced by non-magnetic metals. ML2 display portion 175b that displays in comparison with the judgment limit value, and a plurality of display element rows 175c, 175d that visually display the calculated value calculated this time and the judgment result based on the judgment limit in display colors and the number of lights, 175e.

Thus, in the present embodiment, the magnetic field fluctuation signal Sd derived from the passage of each magnetic field of a plurality of metal samples (Fe, SUS, Non-Fe, etc.) is orthogonally detected to detect the influence of the magnetic metal and the non-magnetic metal. After obtaining the detection data Dx and Dy with large values, the inclination angle θn of the Lissajous figure Hn in the orthogonal coordinate system corresponding to the detection phase is calculated as phase data based on the detection data Dx and Dy, and the calculated phase The data is compared to stored sample signal phase data.

Then, based on the comparison results, for a plurality of types of metal samples (Fe, SUS, Non-Fe, etc.), the phase distribution region of each metal type generated in the orthogonal coordinate system is plotted as a bar-shaped type extending in a predetermined direction. In the display scale area 174, the phase θn of each metal type is arranged in an order corresponding to the difference in phase θn, and the length (predetermined direction) corresponding to the phase variation width due to the difference in magnetism of the sample of each metal type is arranged. , a pointer 174f is displayed on the type display scale area 174 so that the phase of the article or metal currently being inspected can be identified.

Therefore, based on the phase determination result of the metal influence signal generated in the orthogonal coordinate system corresponding to the detection phase, the metal passing through the inspection area Z is detected by the pointer 174f and the plurality of type display areas 174a to 174d. Any one of different color tones can be displayed so as to be identifiable.

In addition, in the present embodiment, not only is the scale displayed in a different color tone for each type of metal having different magnetism in the type display scale area 174, but even within the same type, the phase difference is reflected by the pointer 174f on the scale. It becomes possible to grasp it as a display position. Therefore, the phase .theta.n of the metal influence signal due to the metal mixed in the object to be inspected can be indirectly and quantitatively displayed, and the presence or absence of magnetism of the metal and a more detailed difference in type can be clearly identified and displayed.

Moreover, in the present embodiment, the type display scale area 174, which is the type display means, has a bar shape extending in the direction in which the phases differ, so that the metal type and the difference in magnetism can be more clearly identified and displayed. . In addition, in this embodiment, since the types of different magnetism include at least the types of magnetic metal and the types of non-magnetic metal, it is possible to accurately indicate whether the metal is magnetic or non-magnetic.

(Second embodiment)
FIG. 11 shows an example of metal type display on the display in the metal detector according to the second embodiment of the present invention. It should be noted that each embodiment described below has substantially the same device configuration as the first embodiment described above. , only differences from the first embodiment will be described below.

As shown in FIG. 11, in the display screen 171 of the display 17, from top to bottom, there are an operation mode display area 172, an operation state display area 173, and a magnetic field for the test piece being transported or the NG sample. A type display scale area 274 for displaying different metal types and a metal inspection result display area 175 are arranged.

That is, in the display screen 171, the operation mode display area 172, the operation state display area 173, and the metal inspection result display area 175 are displayed in the same manner as in the first embodiment. , the display mode of the metal type is different from that of the first embodiment.

Specifically, the type display scale area 274 is a type display means capable of displaying the types of articles and test pieces passing through the inspection area Z. , but has a belt-like scale shape curved in a substantially circular arc.

In addition, a plurality of type display areas 274a, 274b, 274c, 274d and 274e for a plurality of types of metal samples are substantially fan-shaped and have respective angular ranges of "Noise" area 274a, "Fe" area 274b and "SUS" area. 274c, a "Non-Fe" region 274d, and an "OVF" region 274e.

Further, on the type display scale area 274, a pointer display 274f extending in the curved radial direction of the type display scale area 274 is superimposed and displayed in a color tone different from that of the type display areas 274a to 274e (here, for convenience of illustration, , the difference in color tone is the difference in hatching).

The "Noise" region 274a corresponds to the distribution region of the phase angle θd of the peak Pw of the Lissajous figure Hg due to the influence of noise, work or vibration in FIG. It corresponds to the distribution region of the phase angle of the peak of the Lissajous figure under the influence of a magnetic metal containing (Fe) and iron as main components.

In addition, the "SUS" region 274c corresponds to a distribution region of the phase angle θn of the peak Pn of the Lissajous figure Hn due to the influence of non-magnetic metal, mainly stainless steel (SUS), and is a "Non-Fe" region. 274d is the distribution area of the phase angle of the peak of the Lissajous figure due to the influence of non-ferrous metals other than steel (iron and iron-based alloys), such as non-ferrous metals such as aluminum (Al) and brass. corresponds to

The "OVF (overflow)" region 274e is a phase angle range of every 180 degrees in which the magnitude of the metal effect can be evaluated from the detection data Dx and Dy. Corners indicate excessive overflow areas.

The pointer display 274f can change its angular position so as to move in the extending direction of the type display scale area 274 according to the magnitude of the phase angle θn, etc. The display position on the type display scale area 274 can be changed. falls within the type display area 274a, 274b, 274c, 274d or 274e, and the difference in color tone with respect to the background area, the type of detected metal or test piece, the presence or absence of magnetism, and the degree of magnetism. degree can be displayed in an easily identifiable manner.

In the present embodiment, similarly to the first embodiment, the inclination angle (θn) of the Lissajous figure in the orthogonal coordinate system corresponding to the detection phase is calculated as the phase of the metal influence signal based on the detection data Dx and Dy. The distribution region of the phase of each metal type generated in the coordinate system is displayed in a scale display region 274 extending in a predetermined direction, in the order of arrangement according to the phase difference of each metal type, due to the difference in magnetism of the sample of each metal type. The scale is arranged in an angle range corresponding to the width of the phase variation, and a pointer is displayed on the scale display so that the phase of the article or metal currently being inspected can be identified.

Therefore, from the pointer display 274f and the plurality of type display areas 274a to 274e, which of the plurality of metal types with different magnetism the metal passing through the inspection area Z is is identified as one of the different color tones. can be displayed as

Further, in the present embodiment, not only is the scale displayed in a different color tone for each type of metal with different magnetism in the type display scale area 274, but even within the same type, the difference in phase is indicated by the pointer display 274f on the scale. can be grasped as the display position of Therefore, the phase of the detected metal is displayed quantitatively, albeit indirectly, so that the presence or absence of magnetism of the metal and a more detailed difference in type can be clearly identified and displayed.

Moreover, in the present embodiment, the type display scale area 274, which is the type display means, extends in the direction in which the phases are different, so that the metal types and their magnetic differences can be more clearly identified and displayed. In addition, in the present embodiment, since the types of different magnetism include at least the magnetic metal type Fe and the non-magnetic metal types SUS and Non-Fe, it is possible to accurately determine whether the metal is a magnetic metal or a non-magnetic metal. It can be displayed effectively.

(Third Embodiment)
FIG. 12(a) shows a display example of the display 17 associated with output processing in the control section in the third embodiment.

As shown in the figure, in the display screen 171 of the display 17, from the top to the bottom, there are an operation mode display area 172, an operation state display area 173, and a magnetic field for the test piece being transported or the NG sample. A type display scale area 374 for displaying different metal types and a metal inspection result display area 175 are arranged.

In the display screen 171, the operation mode display area 172, the operating state display area 173, and the metal inspection result display area 175 are displayed in the same manner as in the first embodiment. , the display mode of the metal type is different from that of the first embodiment.

Specifically, the type display scale area 374 is a type display means of monochrome gradation expression, for example, gray scale, capable of displaying the types of articles and test pieces passing through the inspection area Z. FIG. The type display scale area 374 includes a plurality of type display areas 374a, 374b, 374c, 374d, and 374e for a plurality of types of metal samples, each of which has a "Noise" area 374a, a "Fe" area 374b, a "SUS" area 374c, It is configured as a “Non-Fe” region 374d and an “OVF” region 374e. Each region 374a to 374e is a phase distribution region similar to the corresponding region in the second embodiment.

Here, the “Non-Fe” region 374d in FIG. 12(a) has a different specific gray scale, whereas the other display regions 374a to 374c and 374e have the same gray scale (for example, white). The region is displayed with a specific gradation different from that of the other regions, and the region display functions as a pointer display for specifying the phase region.

The area display in this specific gradation can be moved left and right in the figure, which is the direction in which the type display scale area 374 extends, according to the magnitude of the phase angle θn. The type of the detected metal or test piece can be displayed in an identifiable manner depending on which of the type display areas 374a to 374e the display position is.

Also in this embodiment, for a plurality of types of metal samples, the distribution region of the phase of each metal type generated in the orthogonal coordinate system is displayed in the bar-shaped scale display region extending in a predetermined direction. ) are arranged in an arrangement order according to the difference between them, and a specific gradation display is performed on the scale display so that the phase of the article or metal currently being inspected can be identified. Therefore, it is possible to distinguishably display which of the metal types with different magnetism the metal passing through the inspection area Z belongs to.

(Fourth embodiment)
FIG. 12(b) shows a display example of the display 17 associated with output processing in the control section in the fourth embodiment. This embodiment is similar to the third embodiment.

As shown in the figure, in the present embodiment, in the display screen 171 of the display device 17, an operation mode display area 172, an operation state display area 173, and a metal inspection result display area 175 are different from those in the first embodiment. While the display mode is the same, the type display scale area 474 differs from the first embodiment in the display mode of the metal type.

Specifically, the type display scale area 474 is a type display means capable of expressing the types of articles and test pieces passing through the inspection area Z in multiple colors. The type display scale area 474 includes a plurality of type display areas 474a, 474b, 474c, 474d, and 474e for a plurality of types of metal samples, each of which has a "Noise" area 474a, a "Fe" area 474b, a "SUS" area 474c, It is configured as a “Non-Fe” region 474d and an “OVF” region 474e. Each region 474a to 474e is a phase distribution region similar to the corresponding region in the second embodiment.

The "Fe" region 474b in FIG. 12(b) has a different brightness or 3D effect, etc., while the other display regions 474a and 474c-474e have the same brightness, shading, or other 3D effect, etc. , and the area display in a different highlighting mode from the other areas functions as a pointer display for specifying the phase area. The region display in this highlighting mode can be moved left and right in the figure, which is the direction in which the type display scale region 474 extends, according to the magnitude of the phase angle θn. The type of the detected metal or test piece can be identifiably displayed depending on which of the type display areas 474a to 474e the display position is.

Also in this embodiment, for a plurality of types of metal samples, the distribution region of the phase of each metal type generated in the orthogonal coordinate system is displayed in the bar-shaped scale display region extending in a predetermined direction. ) are arranged in an arrangement order according to the difference between them, and a specific gradation display is performed on the scale display so that the phase of the article or metal currently being inspected can be identified. Therefore, it is possible to distinguishably display which of the metal types with different magnetism the metal passing through the inspection area Z belongs to.

In the above-described first embodiment, the boundary information such as the boundary lines B1 and B2 of the distribution area on the orthogonal coordinates is a map in which the entire fluctuation area at the specific detection phase of the magnetic field fluctuation signal Sd is associated with the orthogonal coordinates. The map area has a curved shape such that the phase angle increases on the high amplitude side (the side where the two components of the orthogonal coordinates increase) from the low amplitude side of the detection signal of the specific article on the map area. However, the boundary information of the distribution area on the orthogonal coordinates is the detection signal of the specific article on the map area when the entire variation area in the specific detection phase of the magnetic field variation signal Sd is made to correspond to the orthogonal coordinates. It may be specified by a boundary calculation formula that specifies a variation point on a curved boundary line so that the phase angle is larger on the high amplitude side than on the low amplitude side.

INDUSTRIAL APPLICABILITY As described above, the present invention can provide a metal detection apparatus capable of accurately and automatically determining whether a metal passing through an inspection area is magnetic or non-magnetic, and displaying the identification. The present invention is useful for all metal detectors that detect metals or metal components in an object to be inspected based on magnetic field fluctuations when the object passes through an alternating magnetic field.

REFERENCE SIGNS LIST 10 metal detector 12 conveyor 14 inspection head 15 article detection sensor 16 operation input unit 17 indicator 21 signal generator (reference signal generator, magnetic field generator)
22 transmission coil (magnetic field generator)
23 differential detector (magnetic field detection unit)
23a, 23b receiving coil 24 detection section (detection circuit section)
24a, 24b mixer 25a, 25b bandpass filter 26a, 26b phase shifter 27a, 27b A/D converter 30 control unit 31 setting unit 32 first memory unit 33 second memory unit 34 third memory unit 35 phase correction unit 36 Determination unit 36a First determination unit (metal presence/absence determination means)
36b second determination unit (phase determination means)
36c third determination unit (metal type determination means)
171 display screen 172 operation mode display area 173 operation state display area 174, 274, 374, 474 type display scale area (type display means)
174a, 174b, 174c, 174d Type display area 174f, 274f Pointer (pointer display)
175 Result display area 274a, 274b, 274c, 274d, 274e Type display area 374a, 374b, 374c, 374d, 374e Type display area 474a, 474b, 474c, 474d, 474e Type display area B1, B2 Boundary line Lg, Ln Amplitude Rx Detection signal of first fluctuation component Ry Detection signal of second fluctuation component Sd Differential detection signal (magnetic field fluctuation signal)
Tp1, Tp2 Metal sample (test piece)
X detection signal (first fluctuation component)
Y detection signal (second fluctuation component)
Z inspection area θn phase (phase angle, tilt angle)
θd phase (phase angle)
τ Transmission signal period

Claims (4)

a magnetic field generator for generating an alternating magnetic field based on the reference signal in an inspection area through which the object to be inspected passes;
a magnetic field detection unit that detects fluctuations in the alternating magnetic field in the inspection area due to passage of the object to be inspected and outputs a magnetic field fluctuation signal;
Detection processing for detecting a first fluctuation component on the in-phase side with respect to the reference signal and a second fluctuation component on the quadrature phase side with respect to the reference signal in the magnetic field fluctuation signal with two detection phases orthogonal to each other. a detection circuit that executes
Based on the first variation component and the second variation component detected by the detection circuit unit, determination processing for detecting metal mixed in the object to be inspected is performed, and the first variation is detected. and a determination unit that displays the level of the component and the second fluctuation component ,
The determination unit is
Sample signal phase data obtained in advance from the magnetic field fluctuation signal detected by passing various metal samples among a plurality of types of metal samples with different magnetism, and detection by passing the test object mixed with metal phase determination means for determining a difference between the phase data of the object signal obtained from the magnetic field fluctuation signal;
Type display areas corresponding to the types of the plurality of types of metals having different magnetism are arranged, and based on the determination result of the phase determining means, the types of metals mixed in the object to be inspected are displayed in the type display areas. and a type display means for displaying pointers in different tones. The type display means arranges, as the type display regions, a plurality of phase regions generated by mutual phase differences in the orthogonal coordinate system corresponding to the two detection phases for the plurality of types of metal samples according to the phase differences. A scale display that is arranged in order in a predetermined direction and displayed in different color tones, and an identification display that displays the phase of the metal currently being detected at a position on the scale display in a different color tone from the color tone of the type display area in a distinguishable manner. 2. The metal detection device according to claim 1, wherein: 3. The metal detecting apparatus according to claim 2 , wherein said type display means displays said scale display in a bar-shaped or curvilinear scale shape extending in said predetermined direction. 4. The metal detection device according to claim 1, wherein the different types of magnetism include at least a type of magnetic metal and a type of non-magnetic metal.

Images