KR20230102105A - Metallic foreign components detecting apparatus and method for detecting metal foreign material thereof - Google Patents

Abstract

The present invention relates to a metal detector and a metallic foreign material detection method of the metal detector and, more specifically, to a metal detector and a metallic foreign material detection method of the metal detector, which allow the metal detector to be utilized at the maximum performance, and can allow a user to easily set the detection sensitivity by visually displaying the detection sensitivity such that the user can set precisely the detection sensitivity according to the characteristics of inspected items. The metal detector according to the present invention includes: a transmitting coil which transmits a transmission signal; a receiving coil which outputs a received signal induced by the transmission signal transmitted from the transmitting coil; a received signal computation unit which calculates the received signal output from the receiving coil while an item to be inspected passes through a tunnel composed of the transmitting coil and the receiving coil, and outputs a metallic foreign object passage signal; a demodulator which outputs the magnitude of the metallic foreign object passage signal output from the computation unit and the phase difference of the metallic foreign object passage signal based on the transmission signal; and a microprocessor which stores the magnitude and the phase difference of the metallic foreign object passage signal output from the demodulator in a memory, and determines whether metallic foreign objects are contained in other inspected items based on the magnitude and the phase difference of the metallic foreign object passage signal stored in the memory.

Description

Metal detector and method for detecting metal foreign matter thereof

The present invention relates to a metal detector and a method for detecting a metal foreign substance therefor, and more particularly, the metal detector can be utilized to its maximum performance, and the detection sensitivity can be set to accurately match the characteristics of an inspection target product by visually displaying it to the user. It relates to a metal detector and a method of detecting a metal foreign body thereof so that the detection sensitivity can be easily set.

A metal detector is generally a device for detecting metal foreign substances remaining in food. The metal detector includes a transmission unit and a reception unit for detecting a metal foreign material using an electromagnetic induction phenomenon. A coil of the transmitter forms a magnetic field, and a receiver composed of two antenna pairs receives a current induced from the transmitter to maintain a balance of signal strength between the two antennas.

When metal entering the tunnel breaks the balance of the electromagnetic field, the disturbed signal is detected, digitized through several times of amplification and filtering, and then displayed on a display device to detect metal foreign matter.

The sensitivity of the metal detector is affected by several factors. The main causes are the size of the metal detector tunnel, moisture and salt conditions of the product, inverters that generate radiation noise, and static electricity that can occur in dry production sites. Among them, the change in detection sensitivity according to the moisture and salt state of the product can be coped with to some extent by resetting the detection method, variation of various frequency occurrences, and sensitivity discrimination criteria.

These metal detectors are used in the process of checking whether metallic foreign substances are mixed in the field of quality control in the food manufacturing process. Due to the transfer of charge by moisture, the metal detector can determine that there is a metal foreign body in the inspection target product.

In order to prevent this phenomenon, the conventional metal detector discriminates the magnitude and phase of the received signal through a phase demodulation circuit added to the receiving part of the metal detector, and the magnitude and phase change of the received signal generated when the inspection target passes through the tunnel. is stored and it is operated by determining whether there is a metal foreign object in the inspection target product by determining whether the received signal change by the inspection target product that passes later is a good product or out of the size and phase change standards of the stored reception signal. .

In the above-described conventional metal foreign matter discrimination method of the metal detector, as a procedure for checking how much the inspection target product without metal foreign matter affects the detection signal of the metal detector, the magnitude of the signal change and the phase change of the received signal A measurement step is required.

In the case where there is no moisture or salt in the object to be inspected or completely frozen and no ionized moisture, the received signal of the metal detector can be operated to determine it as a metal foreign object even if there is any change. However, in the case of an object to be inspected that contains even a little bit of moisture or salt, the object to be inspected causes a magnitude of a reception signal of the metal detector and a phase difference between a transmission signal and a reception signal.

In order not to erroneously judge a normal inspection target product as a metal foreign body product containing a metal foreign body, when a normal inspection target product passes through the metal detector, the maximum value of the size change of the received signal and the phase of the received signal at that time are sent to the metal detector in advance. should be set Here, the size adjustment of the received signal for determining the inspected product as a normal product is generally set to "sensitivity", and the phase of the received signal is set to a value called "phase" (or "characteristic") in the metal detector. do. These terms may be used differently depending on the manufacturer of the metal detector.

It is impossible for users of metal detectors to visually check "sensitivity" and "phase" (or "characteristics") at certain values depending on the item to be inspected to pass through the metal detector they are using, so "sensitivity" and "phase" (or "characteristic") to a random value, continuously pass the inspection target product through the metal detector, find the optimal value to avoid misdiagnosing a normal product as a foreign metal product, or automatically The setting function is used to find and set the optimal value that does not misjudge.

However, in this process, if the optimal value is not properly set, a normal product is misjudged as a foreign metal product, or the criterion is set excessively low, so the maximum performance of the metal detector cannot be used, resulting in "sensitivity" and "phase". There is a problem of not detecting metal foreign matter that could have been detected if " (or "characteristic") was set to an appropriate value. In addition, there is a problem in that the user cannot even check whether or not the metal detector is in a state in which the metal detector can be utilized with the maximum performance with the current setting value.

Korean Registered Patent Publication No. 10-1603092 (registered on March 8, 2016)

An object of the present invention is to provide a metal detector that can easily set the detection sensitivity by visually displaying the detection sensitivity so that it can be accurately set to match the characteristics of an inspection target product, and a metal foreign material detection method thereof.

In addition, to provide a metal detector and its method for detecting metal foreign substances that can easily determine whether or not the metal detector for detecting metallic foreign substances is operating in an optimal setting in the production process of food, etc. there is.

A metal detector according to the present invention for achieving the above object includes a transmission coil for transmitting a transmission signal; a receiving coil outputting a received signal derived by the transmission signal transmitted from the transmission coil; a received signal calculating unit which calculates the received signal output from the receiving coil and outputs a metal foreign object passing signal while the object to be inspected passes through the tunnel composed of the transmitting coil and the receiving coil; a demodulator outputting a phase difference of the foreign object passing signal based on the size of the foreign object passing signal output from the calculation unit and the transmission signal; and storing the magnitude and phase difference of the metal foreign object passing signal output from the demodulator in a memory device, and including the metal foreign object of another inspection target product based on the magnitude and phase difference of the metal foreign object passing signal stored in the memory device. It includes; a microprocessor that determines whether or not.

A metal foreign object detection method according to the present invention is a metal foreign object detection method of a metal detector including a tunnel and a transmitting coil and a receiving coil disposed in the tunnel, at regular intervals while a normal inspection target product passes through the tunnel. A first measurement step of measuring the magnitude and phase difference of the signal passing through the metal foreign material; a criterion setting step of setting a detection criterion by adding a predetermined value to the magnitude and phase difference of the measured foreign material passage signal; a second measurement step of measuring the magnitude and phase difference of the metal foreign object passage signal at regular intervals while the actual inspection target object passes through the tunnel; and a determination step of comparing the magnitude and phase difference of the metal foreign object passage signal measured in the second measuring step with the detection criterion to determine whether or not the metal foreign object is actually detected in the inspection target object.

According to the metal detector and the metal foreign material detection method thereof according to the present invention, there is an advantage in that the detection sensitivity can be easily set by visually displaying the detection sensitivity to accurately match the characteristics of the inspection target product.

In addition, there is an advantage in that it is possible to easily determine whether or not a metal detector for detecting a metal foreign substance is operating in an optimal setting in the production process of food, etc., which detects the foreign substance.

1 is a conceptual diagram for explaining the basic operating principle of a metal detector.
2 is a setting screen of a general metal detector.
3 is a graph showing a masking process of a general metal detector.
4 is a detailed block diagram showing the basic configuration of a metal detector according to an embodiment of the present invention.
5 is a flowchart illustrating a method of detecting a metal foreign material by a metal detector according to an embodiment of the present invention.
6 to 9 are views showing results of metal foreign matter detection displayed in graph form through the display device of the metal detector.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The detailed description of the present invention which follows refers to the accompanying drawings which illustrate, by way of illustration, specific embodiments in which the present invention may be practiced. These embodiments are described in sufficient detail to enable one skilled in the art to practice the present invention. It should be understood that the various embodiments of the present invention are different from each other but are not necessarily mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be implemented in one embodiment in another embodiment without departing from the spirit and scope of the invention. Additionally, it should be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the invention. Accordingly, the detailed description set forth below is not to be taken in a limiting sense, and the scope of the present invention, if properly described, is limited only by the appended claims, along with all equivalents as claimed by those claims. Like reference numbers in the drawings indicate the same or similar function throughout the various aspects.

In adding reference numerals to components of each drawing, it should be noted that the same components have the same numerals as much as possible even if they are displayed on different drawings. In addition, in describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description will be omitted.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 1 is a conceptual diagram for explaining the basic operating principle of a metal detector. A metal detector configures a transmission coil and a receiving coil that transmit a metal foreign object detection signal to detect metal foreign objects in a tunnel shape. to determine

1 is a conceptual diagram for explaining the basic operating principle of a metal detector.

As shown in FIG. 1, the metal detector configures one transmit coil and a pair of receive coils in a rectangular or circular tunnel shape, and applies a signal (metal foreign object detection signal) of a constant frequency to the transmit coil. .

The receiving coil consists of a pair of coils disposed at the front and rear of the transmitting coil, and maintains the same distance from the transmitting coil to receive signals of the same strength between the two coils, and if the polarity of the two receiving coils is reversed It is configured so that the output voltage of the signal becomes 0V when the two receiving coils are perfectly balanced.

When the inspection target product passes through the tunnel formed by the transmission coil and the reception coil, if there is a metal foreign object on the inspection target product, eddy current loss occurs on the surface of the metal foreign object due to the AC signal applied to the transmission coil, and this causes the reception The signal reaching the coil will be lost and will be out of balance. When a pair of receiving coils are out of balance, a signal applied to the transmitting coil and induced in the receiving coil has a non-zero magnitude, so a phase difference of the received signal occurs depending on whether the metal foreign object is magnetic or non-magnetic.

When a normal object to be inspected without a metal object passes through the tunnel of the metal detector, the normal object to be inspected does not change the signal reaching the receiving coil. On the other hand, if any change occurs in the received signal, the metal detector just needs to determine that there is a metal foreign object in the product to be inspected. An eddy current loss similar to that occurs and changes the magnitude and phase of the signal reaching the receiving coil.

In this case, in order to prevent the normal inspection target product from being judged as a defective product containing a metal foreign body, masking to prevent processing as a defective product when a signal corresponding to the magnitude and phase of the received signal generated by the normal inspection target product is received ( Maskng) processing is required.

2 is a setting screen of a general metal detector.

Referring to FIG. 2, a general metal detector provides a function of adjusting the size of a received signal so as not to judge a normal product as a defective product and a function of setting a signal of which phase to mask, respectively. Setting items are sometimes named "phase" (or "characteristic").

"Phase" (or "characteristic"), in addition to setting by the user, also uses the automatic setting function provided by the metal detector. The magnitude and phase of the signal when a change occurs is used as a criterion for determining a foreign object.

A general metal detector is implemented in such a way that phase demodulation is performed after a received signal is subjected to a filtering process for amplification and noise removal.

In a circuit that performs phase demodulation in a general metal detector or an algorithm through digital processing, it is configured to operate with the smallest gain when the currently received signal has no phase difference with respect to a preset reference phase, and with a larger gain as the phase difference increases. . That is, when a signal corresponding to a preset reference phase is received, processing is performed with the smallest gain, and as the phase of the received signal differs greatly from the preset reference phase, the largest amplification is performed. As a result, A masking process for the set phase is performed. A graph of this masking process is shown in FIG. 3 .

If the optimal value is not properly set in the masking process, the normal product is judged as a foreign metal product, or the metal foreign matter judgment standard is excessively low and the maximum performance of the metal detector is not used, so the masking process is performed There is a problem of not detecting metal foreign matter that could be detected if an appropriate value was set. In addition, there is a problem in that it cannot be confirmed whether the currently set value is in a state in which the maximum performance of the metal detector can be utilized.

The metal detector according to the embodiment of the present invention having a function of intuitively setting the detection sensitivity to solve the above problems can intuitively set the above-mentioned "sensitivity" and "phase (or "characteristic"), , masking process is not performed through gain control that minimizes the effect of normal products without metal foreign substances on the metal detector.

In the metal detector according to an embodiment of the present invention, when a normal inspection target product passes through a tunnel composed of a transmission coil and a reception coil, the magnitude of the metal foreign object passage signal measured at regular time intervals and the phase difference information between the transmission signal (hereinafter, ' Reference size and phase difference information') is stored in a storage device such as a memory. And, when the magnitude and phase difference information of the metal foreign object passage signal measured when the actual inspection target product passes through the tunnel indicates a predetermined difference from the reference size and phase difference information stored in the memory, the actual inspection target product is the metal foreign material It is characterized by determining that it is included.

In addition, the metal detector according to the embodiment of the present invention, which has a function of intuitively setting the detection sensitivity, changes in the magnitude and phase difference of the metal foreign object passage signal measured at regular time intervals when the actual inspection target product passes through the tunnel. can be visually expressed as a graph through a display device, and a reference line for determining a metal foreign material product can also be expressed as a graph through the display device. Accordingly, the user can grasp at a glance how high the sensitivity of the metal detector is set.

Hereinafter, a metal detector and a metal foreign material detection method thereof according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 is a detailed block diagram showing the basic configuration of a metal detector according to an embodiment of the present invention.

Referring to FIG. 4 , the metal detector 100 according to an embodiment of the present invention includes an oscillation unit 101, a frequency synthesis unit 102, a transmitting amplifier unit 103, a transmitting coil 140, a receiving coil 150, Received signal calculation unit 104, receiving stage amplification unit 105, gain adjustment unit 106, demodulation unit 160, A/D conversion unit 107, input unit 110, display unit 120, microprocessor 170 and a storage device 180 . Two or more of these components may be implemented as one component, or one component may be functionally separated and implemented as two or more components. Also, some of the components shown in FIG. 4 may be omitted, and other components not shown may be added.

The oscillation unit 101 has a function of generating a transmission signal, that is, a metal foreign object detection signal, by using an element having a small rate of change in frequency, such as a crystal oscillator. The metal foreign object detection signal generated by the oscillator 101 is input to the frequency synthesizer 102 .

The frequency synthesis unit 102 may select and output a frequency of low frequency, medium frequency, or high frequency according to the moisture and salt content of the inspection target product. At this time, the oscillator 101 may select a frequency according to the control signal of the microprocessor 170 . In general, a frequency of 30 to 100 KHz is used for products to be inspected that have a high content of moisture and salt (e.g., kimchi, cheese, etc.) : For frozen products, powder products), a frequency of 100~1000KHz is used.

The transmitter amplifier 103 amplifies the transmission signal, which is the metal foreign object detection signal provided from the frequency synthesizer 102, and provides it to the transmission coil 140, so that the transmission signal to the reception coil 150 can pass through the wireless space. Supply enough power to reach through. As shown in FIG. 1, the transmitting coil 140 may be composed of one.

The received signal calculation unit 104 may output a metal foreign object passing signal by summing the received signals received through the receiving coils 150 configured as one pair in opposite polarity to each other.

When the reception characteristics of the two reception coils 150 are the same, the reception signal calculator 104 may be configured to cancel each other. In this state, when an inspection target product containing a metal foreign object passes through a tunnel composed of a transmission coil 140 and a reception coil 150, the reception coil 150 may enter the tunnel, pass through the tunnel, or exit the tunnel according to the progress position. An imbalance of the induced signal is generated, and a different metal foreign object passage signal appears than when the inspection target product does not contain the metal foreign object.

The receiving end amplifying unit 105 amplifies the metal foreign object passage signal provided from the received signal calculating unit 104 . Here, the gain of the receiving end amplification unit 105 may be adjusted by the gain adjustment unit 106 controlled by the microprocessor 170 .

The demodulation unit 160 composed of a phase demodulation circuit is configured to determine the magnitude (or amplitude) of the foreign material passage signal generated when the inspection target product passes through the tunnel and the difference between the phase of the transmission signal and the phase of the foreign material passage signal (hereinafter, ' referred to as 'phase difference').

The A/D conversion unit 107 converts analog information about the magnitude and phase difference of the metal foreign object passing signal output from the demodulation unit 160 into digital information and provides it to the microprocessor 170 . Here, the demodulation unit 160 and the A/D conversion unit 107 may be configured as one unit.

The memory device 180 stores the magnitude and phase difference information of the metal foreign object passing signal provided to the microprocessor 170 through the demodulator 160 and the A/D converter 107 according to the instructions of the microprocessor 170. Alternatively, the magnitude and phase difference information of the stored metal foreign material passing signal may be provided to the microprocessor 170 at the request of the microprocessor 170 .

The microprocessor 170 controls the overall operation of the metal detector 100. In particular, it is involved in frequency selection of the frequency synthesis unit 102, gain selection of the gain adjustment unit 106 for adjusting the gain of the receiving end amplification unit 105, and the like. The corresponding frequency or gain may be input from the user through the input device 110, and the microprocessor 170 controls various components of the metal detector 100 according to the user input.

The microprocessor 170 may set a period in which the metal foreign object passage signal is output from the received signal operation circuit 104 while the inspection target object passes through the tunnel. That is, the microprocessor 170 may control the metal foreign object passage signal to be output from the reception signal operation circuit 104 at regular time intervals while the object to be inspected passes through the tunnel. The period or the predetermined time interval may be set to a specific value by default in the microprocessor 170, or may be changed to another value by the user through the input device 110.

The microprocessor 170 may store the magnitude and phase difference information of the foreign object passage signal in the memory device 180 and read the magnitude and phase difference information of the foreign object passage signal stored in the memory device 180 .

The microprocessor 170 may control the display device 120 to display a graph based on the size and phase difference information of the foreign object passage signal. In addition, it is possible to set a detection decision reference line or control the set detection decision reference line to be displayed through the display device 120 . In addition, the display device 120 may display a graph based on the magnitude and phase difference information of the metal foreign object passage signal for other inspection target products along with the detection decision reference line.

The microprocessor 170 determines whether or not other objects to be inspected that have passed through the tunnel contain a metal foreign object based on the magnitude and phase difference information of the metal foreign object passage signal stored in the memory device 180, thereby detecting the metal foreign object. can output The microprocessor 170 may control the metal foreign object detection result to be displayed in real time through the display device 120, and may notify the user through a speaker or the like when a metal foreign object is captured.

The display device 120 may be implemented with various devices, such as visual display devices such as monitors and displays, and auditory display devices such as speakers and alarms. Also, in another embodiment, the input device 110 and the display device 120 may be implemented as a single integrated device (eg, a tablet, a touch screen, etc.).

Hereinafter, with reference to the drawings, a metal foreign object detection method of a metal detector according to an embodiment of the present invention will be described in detail. For comparison, a metal foreign object detection method of a general metal detector will first be briefly described.

In a general metal detector, the reference phase of the phase demodulation circuit is set to the phase of a signal received when an object to be inspected without metal foreign matter passes through a tunnel. The output voltage or current increases as the phase of the signal received when an object to be inspected, which is not known to contain a metal foreign object, passes through the tunnel has a larger phase difference from the set reference phase. Normal inspection target products have relatively little signal change due to phase difference, and abnormal inspection target items with metal foreign objects have relatively large signal changes due to phase difference.

On the other hand, the metal foreign object detection method of the metal detector having a function of intuitively setting the detection sensitivity according to the embodiment of the present invention transmits the reference phase at all times, unlike the metal foreign object detection method of the general metal detector described above. It consists of a method of setting the phase of the signal and measuring the phase difference based on the magnitude of the metal foreign material passing signal and the reference phase, which change every moment, at preset time intervals. In addition, after storing the change in the magnitude and phase difference of the measured metal foreign object passage signal for the entire process of the normal inspection target product passing through the tunnel in a memory device such as a memory, the metal generated when the actual inspection target product passes through the tunnel It is determined how much the change in magnitude and phase difference of the foreign object passing signal differs from the change in magnitude and phase difference stored in the memory device to determine whether or not the actual object to be inspected contains a metal foreign object.

Here, the measurement period for measuring the size and phase difference of the metal foreign object passing signal for the inspection target product can be determined by the phase angle resolution to measure the phase difference with the transmission signal during the time the inspection target product passes through the tunnel. . For example, if the product to be inspected passes through the tunnel for 1 second and the size and phase difference of the metal foreign object passage signal are measured at intervals of 1/1000 second, 1000 measurements can be made during the time the product to be inspected passes through, and at this time, the received metal The phase change of the foreign object passage signal can be measured with a resolution of 1/1000 degree, that is, 0.36 degree. Here, the measurement period may be set in various ways in consideration of the passing speed of the inspection target product, the size of the inspection target product, and the passage width of the tunnel.

5 is a flowchart illustrating a method of detecting a metal foreign material by a metal detector according to an embodiment of the present invention.

Referring to FIG. 5 , a metal foreign object detection method of a metal detector according to an embodiment of the present invention includes measuring the magnitude and phase difference of a metal foreign object passing signal for a normal inspection target product (510), and setting a detection criterion. (520), measuring the magnitude and phase difference of the metal foreign object passing signal for the actual inspection target product (530), determining whether or not the foreign object is detected (540), and displaying on the display device (550). there is.

Step 510 of measuring the magnitude and phase difference of the metal foreign object passage signal for the normal inspection target product is a step of measuring the magnitude and phase difference of the metal foreign object passage signal at regular time intervals while the normal inspection target product passes through the tunnel. . The magnitude and phase difference of the metal foreign object passing signal at regular time intervals may be measured by the demodulation unit 160 shown in FIG. 4 . The size and phase difference information for each measured time interval may be stored in the memory 180 by the microprocessor 170 .

Here, the size and phase difference information for each measured time interval may be displayed (550) on the display device 120 in the form of a graph under the control of the microprocessor 170. Specifically, an example in which the magnitude and phase difference information for each measured time interval is displayed in the form of a graph on the display device 120 will be described with reference to FIGS. 6 and 7 .

6 and 7, the horizontal axis represents the phase difference between the transmission signal and the foreign material passage signal, and the vertical axis represents the magnitude of the foreign material passage signal.

In a state in which no inspection target product passes through the tunnel, only a signal having a magnitude and a phase difference of 0 is measured, and as shown in FIG. 6, no graph is displayed on the display device 120.

On the other hand, when a normal inspection target product containing moisture and salt but no metal foreign material passes through the tunnel, the magnitude and phase difference of the metal foreign material passage signal increase and decrease until the normal inspection target product enters the tunnel and passes completely The measurement result may be obtained, and as shown in FIG. 7 , the measurement result may be displayed in the form of a bar type graph on the display device 120 .

Again, referring to FIG. 5 , in step 520 of setting the detection criteria, the detection criteria are set by adding a predetermined value to the size and phase difference information for each predetermined time interval of the normal inspection target product measured in step 510 . Detection sensitivity may vary according to a predetermined value added. The predetermined value to be added may be determined by default or may be determined according to a user input through the input device 110 . Specifically, as shown in FIG. 8 , if a detection decision criterion is set by adding a certain value to the variation of the metal foreign object passage signal generated by a normal inspection target product, a detection decision reference line connecting the corresponding values with a line can be derived. Here, the detection sensitivity can be set to be low, high, or medium by varying the magnitude of a constant value added to the change amount of the foreign material passage signal. The setting of the detection sensitivity can be selected by default or by the user.

Again, referring to FIG. 5, in step 530 of measuring the magnitude and phase difference of the metal foreign object passing signal for the actual inspection target product, while the unknown actual inspection target product containing the metal foreign material passes through the tunnel This is a step of measuring the magnitude and phase of the metal foreign material passage signal at regular time intervals. Here, the size and phase difference information for each measured time interval may be displayed (550) on the display device 120 in the form of a graph under the control of the microprocessor 170.

In step 540 of determining whether or not the metal foreign object is detected, the change in the magnitude and phase difference of the metal foreign object passage signal generated when the actual test target product passes through the tunnel corresponds to the size and phase difference of the normal test target product stored in the storage device 180. It is determined whether the actual object to be inspected contains a metal foreign object by determining how much difference there is from the change.

In step 550 of displaying on the display device, the determination result is displayed on the display device 120 in step 540 . In addition, the change in size and phase difference of the normal inspection target product measured in step 510 can be displayed in the form of a graph on the display device 120, and in step 520, the reference line by setting the detection criteria is displayed in the form of a graph on the display device 120. ), and the change in the size and phase difference of the actual inspection target product measured in step 530 can be displayed on the display device 120 in the form of a graph. An example displayed on the display device 120 will be described with reference to FIG. 9 .

Referring to FIG. 9 , if an actual inspection target product is a normal product that does not contain a metal foreign material, a change in the magnitude and phase difference of the received signal will appear only below the detection decision reference line. On the other hand, if the actual inspection target product is a metal foreign material product containing a metal foreign material, a metal foreign material passing signal exceeding the detection determination reference line may be measured and displayed. When a metal foreign material passage signal exceeding the detection judgment reference line is measured, it is determined that a metal foreign material has been detected in the corresponding actual inspection target product.

As shown in FIGS. 6 to 9, when the graph is displayed on the display device 120 of the metal detector, the user can determine the extent to which the normal inspection target product affects the metal detector, how much the metal detection criterion is, and the current There is an advantage in that it is possible to intuitively obtain information on the extent to which the actual inspection object passing through affects the metal detector, and to check whether the metal detector is being used in an optimal state.

The metal foreign material detection method described above may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer readable medium. A computer-readable recording medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the medium may be those specially designed and configured for the present invention or those known and usable to those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic media such as floptical disks. - includes hardware devices specially configured to store and execute program instructions, such as magneto-optical media, and ROM, RAM, flash memory, and the like. Examples of program instructions include high-level language codes that can be executed by a computer using an interpreter, as well as machine language codes such as those produced by a compiler. The hardware device may be configured to act as one or more software modules to perform the operations of the present invention and vice versa. The method according to the present invention can be executed by various arithmetic devices and arithmetic systems, such as computers, and can also be implemented in the form of computer programs or applications stored in a recording medium and executed by a computer.

In the above, the present invention has been described in terms of specific examples including the embodiments of the present invention, but those skilled in the art can predict various substitutions or modifications in the configuration of the invention described above. You will be able to. In addition, various structural and functional modulations may be made without departing from the scope and technical idea of the present invention. Accordingly, the spirit and scope of the present invention will be broadly understood as set forth in the claims appended hereto.

Claims (10)

a transmission coil for transmitting a transmission signal;
a receiving coil outputting a received signal derived by the transmission signal transmitted from the transmission coil;
a received signal calculating unit which calculates the received signal output from the receiving coil and outputs a metal foreign object passing signal while the object to be inspected passes through the tunnel composed of the transmitting coil and the receiving coil;
a demodulator outputting a phase difference of the foreign object passing signal based on the size of the foreign object passing signal output from the calculation unit and the transmission signal; and
The magnitude and phase difference of the metal foreign object passage signal output from the demodulator is stored in a memory device, and based on the magnitude and phase difference of the metal foreign substance passage signal stored in the memory device, whether or not the foreign object to be inspected is contained in other products to be inspected. a microprocessor that determines;
Including, metal detector. According to claim 1,
The receiving coil includes a pair of receiving coils,
The transmitting coil is disposed between the pair of receiving coils,
The metal detector according to claim 1 , wherein the received signal calculating unit sums the received signals output from the pair of receiving coils in reverse polarity and outputs the metal foreign object passage signal. According to claim 1,
The received signal calculation unit outputs the metal foreign object passing signal at regular time intervals while the inspection target product passes through the tunnel,
Wherein the microprocessor stores the magnitude and phase difference information of the metal foreign object passage signal for each predetermined time interval in the memory device. According to claim 1,
It further includes a display device;
The received signal calculation unit outputs the metal foreign object passage signal at regular time intervals while each of the inspection target product and the other inspection target product passes through the tunnel,
Wherein the microprocessor controls the display device to display a graph related to the magnitude and phase difference information of the metal foreign object passing signal for each predetermined time interval. According to claim 4,
The microprocessor sets a detection criterion by adding a predetermined value to the magnitude and phase difference information of the metal foreign object passing signal for each predetermined time interval for the inspection target object, and sets a reference line for the detection criterion to the display device. Controlled to be displayed together with the graph through, a metal detector. A metal foreign object detection method of a metal detector including a tunnel and a transmission coil and a reception coil disposed in the tunnel,
A first measurement step of measuring the magnitude and phase difference of the metal foreign object passing signal at regular time intervals while the normal inspection target product passes through the tunnel;
a criterion setting step of setting a detection criterion by adding a predetermined value to the magnitude and phase difference of the measured foreign material passing signal;
a second measurement step of measuring the magnitude and phase difference of the metal foreign object passage signal at regular intervals while the actual inspection target object passes through the tunnel; and
a determination step of comparing the magnitude and phase difference of the metal foreign matter passage signal measured in the second measuring step with the detection criterion to determine whether or not the metal foreign matter is detected in the actual inspection target product;
A metal foreign material detection method of a metal detector comprising a. According to claim 6,
and a display step of displaying the magnitude and phase difference information of the metal foreign object passing signal measured in the first measuring step on the display device as a graph. According to claim 7,
In the displaying step, the detection criterion set in the criterion setting step is displayed on the display device together with the graph as a reference line. According to claim 7,
The displaying step further displays the magnitude and phase difference information of the metal foreign object passing signal measured in the second measuring step on the display device as a graph. According to claim 7,
A storage step of storing the magnitude and phase difference information of the metal foreign object passing signal measured in the first measuring step in a storage device; further comprising a metal foreign object detection method of a metal detector.

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