KR20180103306A - The apparatus for identifying metallic foreign components - Google Patents

Abstract

Provided is a metal dust particle detecting apparatus. The metal dust particle detecting apparatus comprises: a conveying unit for conveying an object to be detected; a metal dust particle sensing unit for sensing a change in magnetic property of metal present in the object to be detected by metal dust particle; a magnetic screen unit formed around the metal dust particle sensing unit to surround at least a portion of the metal dust particle sensing unit, and screening an external magnetic field to which the metal dust particle sensing unit may be subjected; an external magnetic field sensing unit installed outside the magnetic screen unit, and sensing a change in the external magnetic field generated outside the magnetic screen unit; and a controller for comparing a sensed result of the metal dust particle sensing unit with a sensed result of the external magnetic field sensing unit to determine whether the metal dust particle is present in the object to be detected.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a water-

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] More particularly, the present invention relates to an apparatus for detecting a metal contained in a product, such as water, in a product to be detected, ≪ / RTI >

The metal-water detector is a device for detecting water mixed with metal in inspection products such as foods. It is composed of an optical detection system using x-rays, an eddy current system using a high frequency magnetic field, and a method in which a metal magnetized by a magnetizing means There is an electromagnetic induction method in which the magnetic field is detected by a magnetic sensor that operates as an electromagnetic induction phenomenon.

Faraday's electromagnetic induction law is generalized by the formula of ε = -N (dΦ / dt) (unit: V), and the induced electromotive force (ε) is proportional to the number of turns of the coil and the rate of change of magnetic flux (Φ) with time. At this time, in order to easily detect the signal generated by the movement of the water, the number of turns of the coil is unchanged. Therefore, the metal passing through the magnetic field must increase the moving speed of the water, or the metal must increase the degree of magnetization of the water.

Korean Registered Patent No. 10-0794907 (Publication Date January 08, 2008)

It is an object of the present invention to provide a water detecting apparatus in which when a metal contains water in the object to be detected, the metal facilitates the detection of water, and at the same time, Wherein the metal is capable of distinguishing a malfunction due to a change in water and an external magnetic field so as not to deteriorate characteristics.

The present invention is not limited to the above-described embodiments, and various changes and modifications may be made without departing from the spirit and scope of the invention.

According to an aspect of the present invention, there is provided a metal-water detection device including: a transport unit for transporting a substance to be detected; a magnetic property change caused by water in a metal present in the substance to be detected; Wherein the metal surrounds the water sensing part and surrounds at least a part of the water sensing part so that the metal shields the external magnetic field which may be affected by the water sensing part, An external magnetic field sensing unit provided outside the magnetic shield unit for sensing a change in an external magnetic field generated outside the magnetic shield unit and a sensing result of the metal sensing unit and a sensing result of the external magnetic field sensing unit, And a controller for determining whether or not the metal is present in the object to be detected.

The metal sensing unit may perform a sensing operation using an electromagnetic induction method or a magnetic field detection method.

The magnetic shield may be formed of a mu-metal, a silicon steel plate, or an iron steel sheet.

A plurality of external magnetic field sensing units may be provided outside the magnetic shield.

The metal visually displays the sensing signal of the water sensing unit or the sensing signal of the external magnetic field sensing unit, or whether the metal is water mixed in the sensing object, And a display unit for visually or audibly displaying whether or not the display unit displays the image.

Other specific details of the invention are included in the detailed description and drawings.

When the metal-water detecting device according to the embodiments of the present invention is used, the metal can easily detect the water when the metal is contained in the object to be detected, and the metal in the object to be detected senses the water It is possible to prevent a malfunction in which the metal detection sensor is affected by an external magnetic field to erroneously determine whether or not the metal is present.

The detection strength of the metal-water detecting device can be improved, and water can be prevented from being contained in the object to be detected in order to secure the safety of the product.

The effects of the present invention are not limited to the above effects and can be variously extended without departing from the technical idea and scope of the present invention.

1 to 6 are perspective views schematically showing a metal water detection apparatus according to embodiments of the present invention.
FIGS. 7A to 7D are views showing a metal detection method applicable to the embodiments of the present invention in a time sequence.
FIG. 8 is a block diagram schematically showing a configuration of a metal detection apparatus applicable to the embodiments of the present invention. FIG.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

The terminology used herein is for the purpose of illustrating embodiments and is not intended to be limiting of the present invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. It is noted that the terms "comprises" and / or "comprising" used in the specification are intended to be inclusive in a manner similar to the components, steps, operations, and / Or additions.

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. In addition, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

The metal-water detecting apparatus is an apparatus for detecting water, which is abnormally mixed in a test stand, and is used in an inspection process in the food manufacturing field, the chemical field, and the textile field. An optical method using an X-ray or a laser, a method using electromagnetic induction, or a magnetic field detection method can be used.

The electromagnetic induction system is composed of a transmitter coil composed of one coil and a receiver coil composed of two or more coils so that an AC signal is applied to the transmitter coil and a signal guided to the receiver coil is detected, And determines whether or not the metal in the inspection table product is water.

The magnetic field detection system includes at least one permanent magnet and at least two magnetic sensors so that the magnitude of the signal of the magnetic sensor, which is determined by the distance between the permanent magnet and the magnetic sensor and the magnetic force of the permanent magnet, By comparison, it detects the change when the inspection product passes and acts as a principle to determine whether metal is present or not.

At this time, there is no change in the signal of the magnetic sensor when the nonmagnetic material does not affect the magnetic field, but when the metal magnetized by the magnetic material or the permanent magnet passes through the magnetic sensor, the output signal of the magnetic sensor changes This is to use the metal as a basis for judging the existence of water.

In the electromagnetic induction method or the magnetic field detection method, when the strength of the magnetic field changes outside the metal-water detecting device, there is a problem that the metal determines that water exists even though the metal does not pass through the water- Lt; / RTI > This is because the change of the external magnetic field affects the magnetic sensor in the electromagnetic induction type receiving coil or the magnetic field detection system to change the output signal, which causes the water to malfunction.

For example, when a user moves a metal moving around an electronic device or the like containing a magnet around a water detecting device, such a magnet causes a change in the magnetic field of the metal in the detection sensor of the water detecting device, The device is likely to determine that the metal is present in the water even though the metal is not present.

For this reason, there is a method of adjusting the sensing sensitivity such that the metal does not respond to the external magnetic field change by using the sensitivity adjusting function which is a function additionally provided to the water detecting device. However, if the sensing sensitivity is reduced, There is a problem that the metal that can be detected by the water is limited, and the water can not be detected by the relatively small metal.

According to the present invention, it is possible to solve the above-mentioned problems and to provide a structure in which the metal shields the external magnetic field around the water detection sensor so as to improve the detection strength of the water detection device and to block the influence of the external magnetic field, Detection device.

1 to 6 are perspective views schematically showing a metal water detection apparatus according to embodiments of the present invention. FIGS. 7A to 7D are views showing a metal detection method applicable to the embodiments of the present invention in a time sequence. FIG. 8 is a block diagram schematically showing a configuration of a metal detection apparatus applicable to the embodiments of the present invention. FIG.

1, a metal water detecting apparatus according to an embodiment of the present invention includes a carry section 100, a metal water sensing section 127, a magnetic shield section 200, The unit 127 may include, for example, an entrance sensor coil 120, a magnetization unit 110, and a detection unit sensor coil 125. And a control unit (refer to FIG. 8) 130 for controlling the operation of the components.

The carry section 100 has a function of transporting the object 10 in a predetermined direction and may be a mechanical device such as a conveyor belt. 1, the object 10 placed on the carry section 100 is transported in the direction of the arrow. The rotational speed of the motor (not shown) that drives the carry section 100 determines the carry speed of the carry section 100 and the moving speed of the object 10 to be inspected moves the motor And the rotational speed of the engine. The control unit 130, which will be described later, controls the rotational speed of a motor (not shown) to adjust the moving speed of the object 10 placed on the carry section 100. Here, the object 10 to be detected may be food, clothing, and the like, but is not limited thereto.

The metal water sensing unit 127 senses a change in magnetic property of the metal existing in the object to be detected 10 with water. The metal water is abnormally contained in the object 10 to be detected, and when the metal is mixed with water for a product such as food or clothing, the product may be harmed by consumers. Therefore, A metal water sensing unit 127 is used.

For example, the metal water sensing portion 127 may be formed to include the configuration (the entrance sensor coil 120, the magnetization portion 110, and the detection portion sensor coil 125) as shown in Fig. However, in the example shown in FIG. 1, the metal is one embodiment of the water sensing part 127, and the present invention may be applied to the modification.

The magnetizing portion 110 is provided at a predetermined position on the conveyance path of the object 10 to be detected and the entrance sensor coil 120 is provided at the front end of the magnetizing portion 110 in the conveying path, May be provided at the rear end of the magnetizing portion 110 in the transport path. That is, as shown in FIG. 1, the entrance sensor coil 120, the magnetization unit 110, and the detection unit sensor coil 125 may be disposed at predetermined intervals along the conveying direction of the carry section 100. The object 10 to be detected 10 passes through the entrance sensor coil 120, the magnetizing unit 110 and the detection unit sensor coil 125 along the conveying path of the conveying unit 100.

The magnetizing portion 110 serves to magnetize water by a metal which may be mixed in the object 10 to be detected. The magnetizing portion 110 may have a rectangular frame shape having a cavity region through which the carry section 100 passes, and surround the carry section 100, as shown in FIG. The magnetization part 110 includes an upper magnetization part 110u provided at the upper part and a lower magnetization part 110d provided at the lower part. The upper and lower magnetization parts 110u and 110d are made of strong magnets, The metal in the object to be detected 10 can magnetize the water. Of course, the magnetizing portion 110 may have any structure other than a strong magnet as long as it can magnetize a metal material or the like.

When the metal contained in the object 10 to be detected is magnetized while the water passes through the magnetization portion 110, the detection sensitivity of the detection sensor coil 125, which is then passed through, can be increased.

Specifically, Faraday's electromagnetic induction law is generalized by the formula of ε = -N (dΦ / dt) (unit: V), and the induced electromotive force (ε) is a function of the number of turns of the coil and the rate of change of the magnetic flux When the metal contained in the object 10 is magnetized, the magnitude of the generated electromotive force is increased, so that the detection sensitivity of the detection unit sensor coil 125 can be improved.

In addition, the control section 130 may increase the rate of change of the magnetic flux density by increasing the moving speed of the carry section 100, thereby improving the detection sensitivity in the detection section sensor coil 125. [

The entrance sensor coil 120 may have a rectangular frame shape having a cavity area through which the carry section 100 passes and may surround the carry section 100. [ The entrance sensor coil 120 may include an entrance upper sensor coil 120u and an entrance lower sensor coil 120d. The entrance upper sensor coil 120u functions to generate a magnetic field and the entrance lower sensor coil 120d functions to receive the magnetic field. A large magnetic flux is generated by the magnetic field generated by the entrance upper portion sensor coil 120u and an induction electromotive force signal generated when the metal in the object to be inspected 10 changes the magnetic flux of the water is sensed by the entrance subordinate sensor coil 120d , It is possible to detect whether or not the metal is mixed with water in the object 10 to be detected.

One end of the entrance upper portion sensor coil 120u and the entrance lower portion sensor coil 120d have a structure in which a copper wire is wound around the iron core. And the other end of the incoming lower sensor coil 120d which senses the induced electromotive force signal may be connected to an amplifier (not shown) to be described later.

The detection section sensor coil 125 may have a rectangular frame shape having a cavity area through which the carry section 100 passes and may surround the carry section 100. The detection section sensor coil 125 may include a detection section upper sensor coil 125u and a detection section lower sensor coil 125d. The detection section upper sensor coil 125u functions to generate a magnetic field, and the detection section lower sensor coil 125d functions to receive the magnetic field. A large magnetic flux is generated by the magnetic field generated by the detection section upper sensor coil 125u and an induction electromotive force signal generated by the change of the magnetic flux of water in the metal in the object 10 to be sensed by the sensor lower sensor coil 125d, It is possible to detect whether or not the metal is mixed with water in the detection object 10. This is the same as the entry sensor coil 120 described above.

However, since the induction electromotive force signal received by the detection unit lower sensor coil 125d is a signal generated by water magnetized by the magnetization unit 110, the induction electromotive force signal received by the entrance lower sensor coil 120d Signal. With such a different signal, the metal-water detecting device according to the present invention makes it possible for the metal in the object 10 to distinguish between water and a packaging material. In this regard, it will be described in more detail with reference to Figs. 7A to 7D.

Since the entrance portion sensor coil 120 and the detection portion sensor coil 125 are spaced apart from each other by a predetermined distance L so that the object 10 having passed through the entrance sensor coil 120 moves and vibrates or impacts There may be a difference in the induced electromotive force signal received at the detecting portion sensor coil 125. [ In this case, it is possible to filter at least one of the detected signals in comparison with a predetermined signal pattern, in order to secure the reliability of water detection by the metal.

One end of the detection section upper sensor coil 125u is connected to one end of the detection section lower sensor coil 125d and a detection section lower sensor coil 125d is connected to the other end of the detection section lower sensor coil 125d. And the other end of the detection part lower sensor coil 125d sensing the induced electromotive force signal from the magnetized metal may be connected to an amplifier (not shown) to be described later.

In the above description, the magnetization part 110 and the entrance / detection part sensor coils 120 and 125 have been described as having a rectangular frame shape having a cavity area. However, . That is, they may be separated from each other in the upper part and the lower part of the carry section 100. That is, the upper magnetization part 110u and the lower magnetization part 110d, the entrance upper part sensor coil 120u and the entrance part lower sensor coil 120d, the detection part upper sensor coil 125u and the detection part lower sensor coil 125d But they can be connected to each other in an appropriate manner and disposed at the upper and lower portions of the carry section 100. [

In order to facilitate the understanding of the invention, the metal detecting apparatus according to the present invention is shown in FIG. 1 to simplify the structure of the water detecting apparatus. However, in addition to the illustrated structure, a motor (not shown) for driving the carry section 100, (Not shown) for supplying driving power to each element such as a heater, a heater, and the like 130 may be added.

In the present invention, the magnetic shielding part 200 is formed such that the metal surrounds at least a part of the water sensing part 127 around the water sensing part 127 so that the metal is not affected by the water sensing part 127 And is configured to shield an external magnetic field that can be received. The magnetic shield 200 may be formed, for example, so that the metal surrounds the water sensing part 127 on one side, two sides, three sides, four sides or six sides, Can be used.

1, the magnetic shielding part 200 is formed so that the metal surrounds the upper / lower / left / right sides of the water sensing part 127 around the position where the metal sensing part 127 is disposed Respectively. However, in order to reduce the cost, the magnetic shield 200 may be formed so that the metal surrounds the upper, left, and right sides (i.e., three sides) of the water sensing unit 127, And may be formed so as to surround either one or two surfaces.

Here, the magnetic shield 200 may be formed of a mu-metal, a silicon steel plate, or an iron steel sheet, and the magnetic shield 200 may block the external magnetic field The metal may be formed to have a proper material and thickness so that the external magnetic field does not affect the water sensing part 127. [

2 and 3, a metal water detection apparatus according to an embodiment of the present invention is provided outside the magnetic shield 200, and detects a change in an external magnetic field generated outside the magnetic shield 200 And external magnetic field sensing units 201, 202, and 203 for sensing the magnetic field.

The external magnetic field sensing units 201, 202, and 203 may be provided outside the magnetic shielding unit 200 in an appropriate number, if necessary, or may be provided in a single or a plurality of magnetic shielding units. That is, the external magnetic field sensing units 201, 202, and 203 may include two or more magnetic shields 200 on the top, bottom, left, right, front, and rear sides of the magnetic shield 200, Can be installed.

4 to 6, the metal water detection device according to the embodiment of the present invention includes a magnetic shielding part 210 formed in a shape to surround all the remaining parts except for the path through which the object 10 to be inspected passes . In this case as well, the external magnetic field sensing units 211, 212, and 213 may be provided outside the magnetic shielding unit 210 in an appropriate number as needed, or may be provided in a single number or in a plurality of units. That is, the external magnetic field sensing units 211, 212, and 213 may include two or more magnetic shields 210 on the top, bottom, left, right, front, and rear sides of the magnetic shield 210 to determine whether the magnetic field has changed Can be installed.

8, the control unit 130 includes at least one amplifier 131-1 and 131-2, filters 132-1 and 132-2, gain controllers 133-1 and 133-2, a converter 134-1 and 134-2, an MCU 134, a storage unit 135, an input unit 136, and a display unit 137. [ However, in another embodiment, each configuration may be implemented in a separate configuration, and only some configurations may be implemented in a separate configuration.

The functions and structures of the carry section 100, the metal-water sensing section 127 and the external magnetic-field sensing section 201 are replaced with the above description, and with respect to Fig. 8, The operation will be explained mainly.

The control unit 130 compares the detection result of the metal sensing unit 127 with the detection result of the external magnetic field sensing unit 201 to determine whether or not the metal is present in the detection target 10.

The first output signal sensed by the metal sensing unit 127 is transmitted to the first amplifier 131-1. In this case, the first amplifier 131-1 may be configured as a single OP-AMP or a plurality of OP-AMPs connected together. The first output signal amplified by the first amplifier 131-1 passes through the first filter 132-1 and noise corresponding to a predetermined frequency is removed. At this time, the first filter 132-1 -1) may be a notch filter that attenuates only a specific frequency. The noise-attenuated first output signal having passed through the first filter 132-1 is transmitted to a first converter (ADC) 134-1 via the first gain controller 133-1 Converted into a digital signal by the first converter 134-1 and transferred to the MCU 134. [

Meanwhile, the second output signal sensed by the external magnetic field sensing unit 201 is transmitted to the second amplifier 131-2. At this time, the second amplifier 131-2 may be configured as a single OP-AMP or a plurality of OP-AMPs connected together. The second output signal amplified by the second amplifier 131-2 passes through the second filter 132-2 and noise corresponding to a predetermined frequency is removed. At this time, the second filter 132-2 -2 may be a notch filter that absorbs only a specific frequency. The noise-attenuated second output signal having passed through the second filter 132-2 is transmitted to the second converter (ADC) 134-2 through the second gain controller 133-2 Converted into a digital signal by the second converter 134-2 and transferred to the MCU 134. [

In this embodiment, the MCU 134 receives the first output signal and the second output signal that are converted to digital signals, but in other embodiments, the first converter 134-1 and the second converter 134-2, The configuration may be omitted or the analog signal passed through the first gain controller 133-1 and the second gain controller 133-2 may be received as they are.

The MCU 134 compares patterns of the first output signal and the second output signal to determine whether the metal is present in the object to be detected 10 or whether there is an influence due to an external magnetic field.

The storage unit 135 may store data on the size of a signal for recognizing the sensed signal as a packaging material. Also, the storage unit 135 may store data on the magnitude of the signal when the mixed substance is metal.

In the above description, the signal size may be an analog signal before passing through the converter, or a digital signal after passing through the converter. Alternatively, the first output signal and the second output signal can be compared based on the pattern of the signal, the frequency of the signal, the amplitude of the signal, the phase of the signal, and the like. Those skilled in the art will appreciate that, based on the first output signal and the second output signal sensed in each sensor coil, these signals can be transformed, processed, and compared with each other in a variety of conventional ways will be.

On the other hand, when the MCU 134 determines that the object to be detected 10 contains water in the object 10, the MCU 134 can display it to the user through audible or visual display. The display unit 137 may be a device such as a display for visual display or a device such as a speaker for auditory display.

More specifically, the display unit 137 visually displays the detection signal of the metal sensing unit 127 or the sensing signal of the external magnetic field sensing unit 201, and determines whether or not the metal is mixed with water in the object to be detected 10 Or it may visually or audibly indicate whether the metal is malfunctioning in response to a change in the external magnetic field.

In FIG. 8, the input unit 136 and the display unit 137 are shown as separate components. Alternatively, the input unit 136 and the display unit 137 may be implemented as a touch screen capable of simultaneously performing input and output operations.

The metal water sensing unit 127 may be equipped with an electromagnetic induction type metal water detection sensor, unlike the above-described example. Such a method includes a transmitting coil and a receiving coil, forms an electromagnetic field by applying an AC signal to the transmitting coil, and detects the water by detecting the magnitude and phase of the receiving signal at the receiving coil. This is a method of applying a signal of a certain frequency to the transmission coil and measuring the amount of change by receiving signals induced in two reception coils arranged at the same intervals as the transmission coil and judging whether or not water is passing through the inside of the detection tunnel . As the test versus merchandise passes through the detection tunnel, changes in the phase and amplitude of the signal received at the receive coil appear, allowing the metal to detect water. In the electromagnetic induction type metal-based water detection system, both non-magnetic and ferromagnetic metal can be detected.

FIGS. 7A to 7D are views showing a metal detection method applicable to the embodiments of the present invention in a time sequence.

7A, the object 10 to be detected 10 is transported at a predetermined speed and direction by the carry section 100 and is transported along the transport direction to the entrance sensor coil 120, the magnetization section 110, The coils 125 are disposed apart from each other. The entrance sensor coil 120 is composed of an entrance upper sensor coil 120u and an entrance lower sensor coil 120d and the magnetization part 110 is composed of an upper magnetization part 110u and a lower magnetization part 110d And the detection section sensor coil 125 may be composed of a detection section upper sensor coil 125u and a detection section lower sensor coil 125d.

In Fig. 7B, the output signal P1 is sensed while the object to be detected 10 passes between the entrance upper portion sensor coil 120u and the entrance lower portion sensor coil 120d. However, if the object to be detected 10 does not contain water, the output signal P1 will not be detected.

Thereafter, as shown in FIG. 7C, the object 10 to be detected passes between the upper and lower magnetization portions 110u and 110d. If a metal is mixed with water in the object 10 to be detected, water will be magnetized, but if the packing material containing aluminum or the like is mixed, magnetization will hardly be achieved. 7C, the object 10 having passed through the magnetizing portion 110 is indicated by a hatched portion. As described above, even if the detection target 10 is a hatched object 10 in FIG. 7C, if the metal is not immersed in water, it can exhibit a state where magnetization is not performed or only minute magnetization is achieved.

Finally, as shown in FIG. 7D, the object to be detected 10 passes through the detection part upper sensor coil 125u and the detection part lower sensor coil 125d to generate the output signal P2.

The output signal P1 and the output signal P2 are amplified and filtered by the respective components shown in FIG. 8, and are transmitted to the MCU 134. The MCU 134 compares the pattern (size, frequency, amplitude, phase, etc.) of the output signal P1 with the output signal P2 to determine whether the substance contained in the object 10 is a packaging material or a metal It can be judged.

For example, when the output signal P1 is not detected but only the output signal P2 is detected, it is determined that the metal contains water in the object to be detected, the output signal P1 is detected, P2 and the output signal P1 exceeds a predetermined threshold value, it can be determined that the metal contains water.

On the other hand, if the output signal P1 is detected but the output signal P2 is the same as the output signal P1 or the difference between the output signal P1 and the output signal P2 is fine (within a predetermined range) It can be judged to be a packaging material. Here, the predetermined range and the predetermined threshold value for the difference between the output signal P1 and the output signal P2 may be stored in the storage unit 135 in advance.

According to the embodiments of the present invention, the metal water sensing unit 127 can sense the signal generated when the object 10 to be detected moves along the carry unit 100 have. Generally, since the signal is very small in size, the signal is amplified using the first amplifier 131-1, and the noise signal mixed into the signal is removed by the first filter 132-1. The signal that has passed through the first gain controller 133-1 is converted into a digital signal by the first converter 134-1 and the MCU 134 senses a change in the size of the digital signal, It is possible to determine whether the signal is water or not. At this time, when the size of the sensing signal is too large due to the influence of the inspecting stand itself, in which the metal is not present, the first gain controller 133-1 is controlled to attenuate the signal amplitude, If it is too small, the signal size can be further amplified.

When signals of the external magnetic field sensing unit 201 are input to the MCU 134 in the same manner, signals of the metal water sensing unit 127 and the external magnetic field sensing unit 201 are compared in real time, It is possible to determine whether the signal is generated by the sensing unit 127 and to determine whether the signal is caused by a change in the external magnetic field or a signal caused by the metal.

If all the cases where the signal change due to the external magnetic field is regarded as a malfunction, if the moment when the external magnetic field is changed and the moment when the metal passes through the water sensing unit 127 are simultaneously detected, the metal can not detect water There is a possibility to pass. Therefore, the above problem can be solved by subtracting the metal from the signal of the external magnetic field sensing unit 201 from the signal of the water sensing unit 127. Since the metal of the external magnetic field sensing unit 201 is magnetically shielded from the water sensing unit 127, the magnitude of the signal for the change of the external magnetic field is different between the inside and the outside of the magnetic shield.

However, since the magnetic shielding unit 200 can not completely shield the external magnetic field, when the magnetic field is changed outside the metal sensing unit, the metal sensing unit (the metal sensing unit 127, the external magnetic sensing unit 201)). An appropriate compensation process is required for this, and a method related to this requires an initial correction for both the signal of the metal water sensing unit 127 and the signal of the external magnetic field sensing unit 201.

In this initial correction method, the metal may be changed from a water sensing unit 127 and an external magnetic field sensing unit 201 by causing a change of a magnetic field by using, for example, a permanent magnet, The MCU 134 measures the change in the signal size at the same time and stores the measured change in the storage unit 135. (2) Next, the ratio of the magnitudes of the two signals and the time difference or phase of the two signals are obtained and stored as correction constants. At this time, when the signal sensed by the external magnetic field sensing unit 201 is converted into a digital signal, if the magnitude of the signal is too large, the second gain controller 133-2 is controlled to attenuate the magnitude of the signal, If the size is too small, the second gain controller 133-2 can be controlled to amplify the signal. (3) Then, when the metal is performing the water detection operation using the constant for calibration stored in the above step, the signal received by the external magnetic field sensing unit 201 when the metal is output to the water sensing unit 127 The difference obtained by subtracting the correction constant can be used as a signal for discrimination of actual metal foreign object. If the signal for discriminating the metal is compared with the threshold value by the setting of the user and the threshold value is exceeded, the metal can be visually and audibly displayed through the display unit 137 as water exists.

When two or more external magnetic field sensing units 201 are provided, a circuit for summing the respective sensor signals may be added.

Even when the magnetic field is changed outside the water detection device by the above-described method, the possibility of malfunctioning can be lowered compared with the conventional metal water detection device, and the metal can improve the water detection efficiency.

Although the present invention has been described in terms of specific embodiments including the preferred embodiments of the present invention, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, It can be predicted. In addition, various structural and functional modifications can be made without departing from the scope and spirit of the present invention. Accordingly, the spirit and scope of the present invention may be understood broadly as described in the claims appended hereto.

100:
110: magnetized portion
120: Inlet sensor coil
125: detection part sensor coil
130:
200: magnetic shielding
201 to 203, 211 to 213: External magnetic field sensing unit

Claims (5)

A conveying unit for conveying the object to be detected;
A metal water sensing unit for sensing a change in magnetic property of the metal existing in the object to be detected with water;
Wherein the metal surrounds the water sensing part and the metal surrounds at least a part of the water sensing part so that the metal shields an external magnetic field that may be affected by the water sensing part;
An external magnetic field sensing unit installed outside the magnetic shield and sensing a change in an external magnetic field generated outside the magnetic shield; And
And a control unit for comparing the detection result of the metal water sensing unit and the detection result of the external magnetic field sensing unit to determine whether metal is present in the object to be detected. The method according to claim 1,
Wherein the metal water sensing unit performs a sensing operation using an electromagnetic induction method or a magnetic field detection method. The method according to claim 1,
Wherein the magnetic shield is formed of a mu-metal, a silicon steel plate, or an iron steel sheet. The method according to claim 1,
Wherein a plurality of external magnetic field sensing units are provided outside the magnetic shield. The method according to claim 1,
The metal visually displays the sensing signal of the water sensing unit or the sensing signal of the external magnetic field sensing unit, or whether the metal is water mixed in the sensing object, And a display unit for visually or audibly displaying whether or not the water-absorbing material is present.

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