JPWO2019016961A1 - Inspection device for magnetic material - Google Patents

Abstract

This magnetic material inspection device (100) includes a CPU (31) that detects the state of a steel wire rope (W) and an offset voltage application unit that applies an offset voltage to a signal receiving end (30a) of a receiving circuit (30). (4), and the CPU (31) is configured to detect an open circuit fault and a short circuit fault of the detection coil (22) based on the change in the voltage level of the offset voltage.

Description

  The present invention relates to a magnetic body inspection apparatus, and more particularly, to a magnetic body inspection apparatus including a differential coil that detects a change in a magnetic field of a magnetic body to be inspected and outputs a detection signal.

  2. Description of the Related Art Conventionally, there has been known a magnetic body inspection apparatus including a differential coil that detects a change in a magnetic field of a magnetic body to be inspected and outputs a detection signal. Such a magnetic body inspection apparatus is disclosed in, for example, Japanese Utility Model Publication No. 53-42727.

  Japanese Utility Model Publication No. 53-42727 discloses a differential transformer, a transmitter for providing an excitation voltage to a primary side of the differential transformer, a transmitter output and a secondary side output of the differential transformer. A fault detecting device for a differential transformer comprising a circuit for outputting a difference is disclosed. Specifically, the output of the oscillator divided by the potentiometer is input to the inverting input of the differential amplifier, and the secondary output of the differential transformer is input to the non-inverting input of the differential amplifier. Then, when the core (magnetic material) of the differential transformer is located on the positive side with respect to the differential transformer (a position closer to one of the two coils included in the differential transformer) The potentiometer is adjusted so that the output of the differential amplifier becomes zero, and the position on the positive side is set as a reference point. When the differential transformer is disconnected or the like, the core (magnetic material) is located at zero displacement (a position at which the distance between each of the two coils included in the differential transformer is substantially equal). Similarly, the output of the working transformer goes to zero.

  Therefore, the differential transformer failure detection device described in Japanese Utility Model Publication No. 53-42727 discloses a method for detecting a failure of the differential transformer when the range from the reference point to just before the zero displacement is used as a detection range. The output of the differential amplifier can be made different from the output of the differential amplifier in the above-described detection range when the differential transformer is not disconnected, so that the disconnection of the differential transformer can be detected. It is configured.

Japanese Utility Model Publication No. 53-42727

  However, in the fault detection device for a differential transformer described in Japanese Utility Model Publication No. 53-42727, the output of the transmitter and the output of the secondary side of the differential transformer are compared in order to detect a disconnection or the like of the differential transformer. And outputs the difference. For this reason, it is necessary to provide a dedicated circuit for outputting a difference for detecting a disconnection or the like of the differential transformer, and there is a problem that the circuit configuration in the device is correspondingly complicated.

  The present invention has been made to solve the above-described problems, and one object of the present invention is to suppress the complexity of a circuit configuration for detecting a failure of a differential coil. An object of the present invention is to provide a failure detection device for a differential transformer.

  In order to achieve the above object, a magnetic body inspection apparatus according to one aspect of the present invention includes a differential coil that detects a change in a magnetic field of a magnetic body to be inspected and outputs a detection signal, and a differential coil. A signal receiving unit that receives the output detection signal, a control unit that detects a state of the magnetic body based on a signal from the signal receiving unit, and a signal receiving unit that is provided between the differential coil and the signal receiving unit. And an offset voltage applying unit that applies an offset voltage to the signal receiving end of the differential coil.The control unit determines at least one of an open fault and a short circuit fault of the differential coil based on a change in the voltage level of the offset voltage. And a control unit for detecting.

  In the inspection apparatus for a magnetic material according to one aspect of the present invention, as described above, the signal is applied to the signal receiving end of the signal receiving unit using the control unit originally provided for detecting the state of the magnetic material. Based on a change in the voltage level of the offset voltage, it is possible to detect at least one of an open fault and a short-circuit fault of the differential coil. As a result, there is no need to separately provide a dedicated circuit for detecting a failure of the differential coil (at least one of an open failure and a short-circuit failure). ) Can be suppressed from becoming complicated.

  In the magnetic body inspection apparatus according to the above aspect, the absolute value of the voltage value of the offset voltage is preferably larger than １ ／ of the difference between the maximum value and the minimum value of the detection signal generated from the differential coil. Here, the signal receiving unit receives a voltage signal obtained by adding a detection signal (AC voltage signal) generated from the differential coil to the offset voltage. Therefore, since the absolute value of the voltage value of the offset voltage is larger than 1/2 of the difference between the maximum value and the minimum value of the detection signal generated from the differential coil, the voltage signal obtained by adding the detection signal to the offset voltage Can be easily set to a range of only one of the positive voltage and the negative voltage.

  In this case, preferably, each of the signal receiving unit and the control unit is configured to operate with either a positive voltage or a negative voltage. With this configuration, each of the signal receiving unit and the control unit can be configured by an element driven by only one of the positive voltage and the negative voltage. As a result, the configuration of each of the signal receiving unit and the control unit can be simplified as compared with the case where each of the signal receiving unit and the control unit is configured by an element driven by both a positive voltage and a negative voltage.

  In the magnetic material inspection apparatus according to the above aspect, preferably, the offset voltage applying unit is provided between the first resistance element unit provided between the differential coil and the signal receiving end, and between the DC power supply and the signal receiving end. And a second resistor element provided in the first resistor element, the second resistor element, and a voltage value of the DC power supply is divided based on the resistance value of each of the differential coils, thereby obtaining a signal. The receiving unit is configured to apply an offset voltage to a signal receiving end. With this configuration, an offset voltage can be applied by simply adding a relatively simple configuration such as the first resistance element section and the second resistance element section to the existing circuit configuration. As a result, it is possible to effectively suppress the complexity of a circuit configuration for detecting a failure of the differential coil (at least one of an open failure and a short-circuit failure).

  In this case, preferably, the second resistance element section has a Zener diode. Here, when the second resistance element section is constituted only by the resistance element, spike noise of the power supply or the like affects the detection result. Therefore, since the second resistance element has a Zener diode, the Zener diode has a high constant voltage characteristic in a predetermined voltage band (it is hardly affected by spike noise). Can be suppressed.

  In the magnetic body inspection apparatus according to the above aspect, preferably, the apparatus further includes an excitation coil for exciting a state of magnetization of the magnetic body, and the signal receiving unit detects a voltage of an excitation coil end of the excitation coil, and controls the voltage. The unit is configured to detect at least one of an open failure and a short-circuit failure of the excitation coil based on a change in voltage at the excitation coil end caused by the flow of the excitation AC current through the excitation coil. According to this configuration, the open-circuit fault and / or the short-circuit fault of the excitation coil are detected based on the change in the voltage level of the end of the excitation coil, thereby detecting the fault (open fault and short-circuit fault) of the excitation coil. It is possible to detect at least one of the open failure and the short-circuit failure of the excitation coil without separately providing a dedicated circuit for detecting at least one of them. As a result, it is possible to suppress the complexity of a circuit configuration for detecting a failure (at least one of an open failure and a short-circuit failure) of the excitation coil.

  In this case, preferably, a DC power supply is connected to one side of the excitation coil, and a transistor that is turned on / off based on a signal from the control unit is connected to the other side of the excitation coil. It is configured to detect at least one of an open failure and a short-circuit failure of the excitation coil based on a change in voltage at the excitation coil end caused by turning on / off of the transistor. With such a configuration, the voltage at the excitation coil end can be changed only by providing a transistor, so that compared to a case where a relatively complicated circuit such as an AC voltage source is provided to change the voltage at the excitation coil end. Further, the complexity of the circuit configuration can be further suppressed.

  According to the present invention, as described above, the complexity of the circuit configuration for detecting the failure of the differential coil can be suppressed.

FIG. 1 is a diagram illustrating an entire configuration of a mobile X-ray fluoroscope including a magnetic body inspection apparatus according to an embodiment. FIG. 4 is a diagram for describing a direction in which a magnetic field is applied by a magnetic field application unit and a configuration of a detection unit according to the embodiment. It is a figure showing composition in an inspection device of a magnetic body by one embodiment. FIG. 5 is a diagram illustrating a voltage at a signal receiving end received by a signal receiving unit according to an embodiment. FIG. 5 is a diagram for explaining a voltage at an excitation coil end received by a signal receiving unit according to one embodiment. FIG. 9 is a diagram illustrating a configuration of an offset voltage applying unit according to a first modification of the embodiment. FIG. 10 is a diagram illustrating a configuration of an offset voltage applying unit according to a second modification of the embodiment. FIG. 11 is a diagram illustrating a circuit configuration for flowing an excitation AC current to an excitation coil according to a third modification of the embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The configuration of the inspection apparatus 100 according to the present embodiment will be described with reference to FIGS. In the present embodiment, an example will be described in which the inspection device 100 is used to inspect the steel wire rope W built in the mobile X-ray imaging device (rounding car) 900. The inspection device 100 is an example of the “magnetic device inspection device” in the claims.

  As shown in FIG. 1, the mobile X-ray imaging apparatus 900 includes an X-ray irradiator E1 configured to be movable up and down (X direction) with respect to a pillar P, and a portable X-ray detector E2. And are configured to be movable by wheels. The X-ray irradiator E1 irradiates the subject with X-rays. The X-ray detector E2 detects X-rays transmitted through the subject and receives an X-ray image. Further, the X-ray irradiator E1 and the X-ray detector E2 are each composed of, for example, an X tube and an FPD (flat panel detector). In the column P, a steel wire rope W for pulling and supporting the X-ray irradiator E1 and an inspection device 100 configured to be movable in the vertical direction (X direction) in which the steel wire rope W extends are built in. Have been. The steel wire rope W is an example of the “magnetic material” in the claims.

  The steel wire rope W is a magnetic material formed by knitting (for example, strand knitting) a magnetic element material having magnetism and made of a long material extending in the X direction. Although not shown, the steel wire rope W passes through a mechanism such as a pulley when moving the X-ray irradiator E1, and is subjected to stress due to the pulley or the like. In order to prevent the steel wire rope W from being cut due to deterioration and to prevent the X-ray irradiator E1 from dropping, the state of the steel wire rope W (whether there is a scratch or the like) is regularly monitored, and the deteriorated steel wire rope W is removed. It is necessary to replace it at an early stage.

  As shown in FIG. 2A, the inspection device 100 is configured to detect a change in a magnetic field (magnetic flux) of the steel wire rope W. In addition, the inspection apparatus 100 includes an inspection unit U including a magnetic field application unit 1, a detection unit 2, and an electronic circuit unit 3, a driver (not shown) and a drive for moving the inspection unit U with respect to the steel wire rope W. (Not shown). The Y direction and the Z direction are two directions orthogonal to each other in a plane perpendicular to the direction in which the steel wire rope W extends.

  The magnetic field application unit 1 is configured to apply a magnetic field in the Y direction in advance to the steel wire rope W to be inspected to adjust the magnitude and direction of the magnetization of the magnetic material. The magnetic field applying unit 1 includes first magnetic field applying units 11a and 11b that apply a magnetic field to the steel wire rope W made of a long material in the Y2 direction, and a first magnetic field applying unit of the detecting unit 2 in the X direction. 11a and 11b, which are provided on the opposite side to the steel wire rope W made of a long material and apply a magnetic field along a Y1 direction parallel to a plane intersecting the X direction and opposite to the Y2 direction. And two magnetic field applying units 12a and 12b. That is, the magnetic field applying unit 1 is configured to apply a magnetic field in a direction substantially orthogonal to the X direction, which is the longitudinal direction of the long material.

  As shown in FIG. 2B, the inspection device 100 includes an excitation coil 21 and a detection coil 22 included in the detection unit 2. As shown in FIGS. 2A and 2B, the excitation coil 21 and the detection coil 22 have a longitudinal direction centered on a direction in which a steel wire rope W, which is a magnetic material made of a long material, extends. Is a coil including a conducting wire portion that is wound a plurality of times along the X direction and formed into a cylindrical shape along the X direction (longitudinal direction) in which the steel wire rope W extends. Therefore, the surface formed by the conductor portion to be wound is substantially perpendicular to the longitudinal direction, and the steel wire rope W passes through the inside of the coil. The detection coil 22 is provided inside the excitation coil 21. The arrangement of the detection coil 22 and the excitation coil 21 is not limited to this. Note that the detection coil 22 is an example of a “differential coil” in the claims.

  The excitation coil 21 excites the state of magnetization of the steel wire rope W. More specifically, the configuration is such that a magnetic field generated based on the excitation AC current is applied along the X direction inside the excitation coil 21 when the excitation AC current flows through the excitation coil 21.

  The detection coil 22 is configured to detect a change in the magnetic field in the X direction of the steel wire rope W to be inspected and output a detection signal (voltage). That is, the detection coil 22 detects a change in the magnetic field in the X direction intersecting in the Y2 direction with respect to the steel wire rope W to which the magnetic field is applied in the Y2 direction by the magnetic field applying unit 1, and detects the detected steel wire rope W Is configured to output a voltage based on the change in the magnetic field in the X direction. The detection coil 22 is arranged so that substantially all of the magnetic field generated by the excitation coil 21 can be detected (input).

  The detection coil 22 is a differential coil composed of two detection coil portions 22a and 22b. Further, the detection coil 22 detects a change in the magnetic field in the X direction of the steel wire rope W whose magnetization state is excited by the magnetic field generated by the excitation AC current flowing through the excitation coil 21.

  Further, when the steel wire rope W has a flaw or the like, the total magnetic flux (the value obtained by multiplying the magnetic field by the magnetic permeability and the area) of the steel wire rope W becomes small at the flawed part. As a result, for example, the value of the detection voltage of the detection coil 22a located at a location having a flaw or the like is smaller than that of the detection coil 22b. Detection signal). That is, the detection signal in a portion without a flaw or the like becomes substantially zero, and the detection signal in a portion with a flaw or the like has a value larger than zero. Therefore, in the differential coil, a clear signal (S / S Signal with a good N ratio) is detected. Thus, the electronic circuit unit 3 can detect the presence of a scratch or the like on the steel wire rope W based on the value of the difference between the detection signals.

  As shown in FIG. 3, the inspection device 100 (see FIG. 2) includes a receiving circuit 30 included in the electronic circuit unit 3. The receiving circuit 30 receives a detection signal (voltage) output from the detection coil 22. Further, the receiving circuit 30 detects (receives) the voltage of the excitation coil end 21a of the excitation coil 21. The receiving circuit 30 is an example of the “signal receiving unit” in the claims.

  The inspection device 100 (see FIG. 2) includes a CPU 31 included in the electronic circuit unit 3. The CPU 31 is provided with an AD converter (not shown). The CPU 31 converts an analog detection signal from the receiving circuit 30 into a digital detection signal using an internal AD converter. Note that the CPU 31 is an example of a “control unit” in the claims.

  In addition, the inspection device 100 (see FIG. 2) includes an offset voltage application unit 4 provided between the detection coil 22 and the reception circuit 30. The offset voltage applying unit 4 includes a resistance element 40 provided between the detection coil 22 and the signal receiving end 30a of the receiving circuit 30. Further, the offset voltage applying unit 4 includes a resistance element 41 provided between the signal receiving end 30a and the DC power supply 5 that supplies power to the receiving circuit 30 and the like. The resistance element 40 and the resistance element 41 are examples of the “first resistance element part” and the “second resistance element part” in the claims, respectively.

  The receiving circuit 30 includes a data output interface 32 and a bipolar transistor 33. The data output interface 32 is connected to an external PC (not shown) or the like, and outputs digital data of processed detection signals and alarm signals. As will be described later in detail, the bipolar transistor 33 is provided for generating an exciting AC current in the exciting coil 21. An AC voltage signal output from the CPU 31 is input to the base of the bipolar transistor 33. Note that a resistance element 101 is provided between the base of the bipolar transistor 33 and the CPU 31. The bipolar transistor 33 is an example of the “transistor” in the claims.

  Here, in the present embodiment, the offset voltage applying unit 4 is configured to apply an offset voltage having a predetermined voltage value to the signal receiving end 30a. Specifically, the offset voltage applying unit 4 divides the voltage value of the DC power supply 5 based on the respective resistance values of the resistance element 40, the resistance element 41, and the detection coil 22, thereby forming the reception circuit 30. It is configured to apply an offset voltage to the signal receiving end 30a.

  Here, the resistance value of the resistance element 40, the resistance value of the resistance element 41, the resistance value of the detection coil 22, the input resistance value of the receiving circuit 30, and the voltage value of the DC power supply 5 are denoted by R1, R2, Rs, respectively. An offset voltage value is calculated as Ra and V. In this case, the offset voltage value is V × (R1 × Ra + Ra × Rs) / (R1 × R2 + R1 × Ra + R2 × Ra + R2 × R2 + Ra × Rs).

  The CPU 31 is configured to detect an open failure and a short-circuit failure of the detection coil 22 based on a change in the voltage level of the offset voltage. Specifically, when the detection coil 22 has an open failure, the resistance value Rs of the detection coil 22 becomes extremely high, so that the offset voltage is fixed to V which is the voltage value of the DC power supply 5. Further, when the detection coil 22 has a short-circuit fault, the resistance value Rs of the detection coil 22 becomes extremely low (becomes close to zero), so that the offset voltage becomes V × (R1 × Ra) / (R1 × R2 + R1 ×). Ra + R2 × Ra + R2 × R2). For example, the CPU 31 sets the offset voltage (the voltage of the signal receiving end 30a) to the voltage (V or V × (R1 × Ra) / By detecting from a signal from the receiving circuit 30 that the detection coil 22 is fixed to (R1 × R2 + R1 × Ra + R2 × Ra + R2 × R2), an open fault or a short fault of the detection coil 22 is detected.

  As shown in FIG. 4, when the detection coil 22 is outputting a detection signal (voltage), the offset voltage is added to the detection signal output by the detection coil 22 in the voltage of the signal receiving end 30 a detected by the reception circuit 30. Voltage. Here, a voltage waveform (waveform indicated by a dotted line) of the signal receiving end 30a when no offset voltage is applied will be described as a comparative example. In this case, the detection signal (voltage) of the detection coil 22 becomes the voltage of the signal receiving end 30a as it is. That is, when the detection signal of the detection coil 22 is a positive voltage, the voltage of the signal receiving end 30a is also a positive voltage, and when the detection signal of the detection coil 22 is a negative voltage, the voltage of the signal receiving end 30a is also a negative voltage.

  Here, in the present embodiment, the absolute value of the voltage value of the offset voltage is larger than 差分 of the difference between the maximum value and the minimum value of the detection signal (voltage) generated from the detection coil 22. Specifically, when the maximum value and the minimum value of the voltage of the signal receiving end 30a are Vmax and Vmin, respectively, the difference between the maximum value and the minimum value of the detection signal (voltage) generated from the detection coil 22 is: Vmax−Vmin. That is, the resistance values of the resistance elements 40 and 41 are selected such that the offset voltage becomes higher than (Vmax−Vmin) / 2.

  In the present embodiment, each of the receiving circuit 30 and the CPU 31 is configured to operate only with a positive voltage. Specifically, an operational amplifier (not shown) included in the reception circuit 30 and a circuit such as an AD converter (not shown) included in the CPU 31 can be driven only by a positive voltage. In this case, an offset voltage such that the minimum value (Vmin) of the voltage of the signal receiving end 30a detected by the receiving circuit 30 becomes a positive voltage is applied to the signal receiving end 30a.

  Further, as shown in FIG. 3, the DC power supply 5 is connected to one side of the excitation coil 21. A resistance element 102 is provided between the excitation coil 21 and the DC power supply 5. By providing the resistance element 102, it is possible to protect an excessive current from flowing through the excitation coil 21 when the excitation coil 21 is short-circuited. The collector of the bipolar transistor 33 is connected to the other side of the excitation coil 21. Note that the emitter of the bipolar transistor 33 is grounded. The bipolar transistor 33 turns on and off based on a signal (AC voltage signal) from the CPU 31 input to the base.

  Here, in the present embodiment, as shown in FIG. 5, the CPU 31 performs the open failure and the short circuit of the excitation coil 21 based on the change in the voltage of the excitation coil end 21a caused by the excitation alternating current flowing through the excitation coil 21. It is configured to detect a failure. Specifically, the CPU 31 is configured to detect an open failure and a short-circuit failure of the excitation coil 21 based on a change in the voltage of the excitation coil end 21a due to the turning on and off of the bipolar transistor 33.

  More specifically, as shown in FIG. 5A, when the excitation coil 21 is not out of order, the maximum value of the voltage of the excitation coil end 21a becomes the voltage value V of the DC power supply 5 and the minimum value is The voltage value V1 is smaller than the voltage value V. That is, when the bipolar transistor 33 is off, no exciting AC current flows through the exciting coil 21, and the voltage value of the exciting coil end 21 a becomes the voltage value V. When the bipolar transistor 33 is turned on, the excitation AC current flows through the excitation coil 21, so that the voltage value of the excitation coil end 21 a becomes the voltage value V 1.

  As shown in FIG. 5B, when the excitation coil 21 has a short-circuit fault, the maximum value of the voltage of the excitation coil end 21a becomes the voltage value V of the DC power supply 5 and the minimum value is the voltage value. The voltage value V2 is smaller than the value V and the voltage value V1 (see FIG. 5A). That is, when the bipolar transistor 33 is off, no exciting AC current flows through the exciting coil 21, and the voltage value of the exciting coil end 21 a becomes the voltage value V. Further, when the bipolar transistor 33 is on, the excitation AC current flows through the excitation coil 21, and the voltage value of the excitation coil end 21 a becomes the voltage value V2. Note that the voltage value V2 is smaller than the voltage value V1 by an amount due to the resistance component of the excitation coil 21. Further, the voltage value V2 is a voltage value caused by the electric characteristics of the bipolar transistor 33.

  Further, as shown in FIG. 5C, when the excitation coil 21 has an open failure, the voltage of the excitation coil end 21a is fixed to the voltage value V of the DC power supply 5. That is, the excitation AC current does not flow through the excitation coil 21 both when the bipolar transistor 33 is off and when it is on, and the voltage at the excitation coil end 21 a becomes the voltage value V.

  That is, the CPU 31 detects the state of the excitation coil 21 based on whether the voltage waveform of the excitation coil end 21a detected by the receiving circuit 30 is one of the waveforms in FIGS.

(Effect of this embodiment)
In the present embodiment, the following effects can be obtained.

  In the present embodiment, as described above, the detection coil 22 that detects a change in the magnetic field of the steel wire rope W to be inspected and outputs a detection signal, and the receiving circuit that receives the detection signal output from the detection coil 22 30, a CPU 31 that detects the state of the steel wire rope W based on a signal from the receiving circuit 30, and an offset voltage that is provided between the detecting coil 22 and the receiving circuit 30, and that applies an offset voltage to the signal receiving end 30 a of the receiving circuit 30. The inspection apparatus 100 is configured so as to include an offset voltage applying unit 4 for applying the voltage, and a CPU 31 that detects an open failure and a short circuit failure of the detection coil 22 based on a change in the voltage level of the offset voltage. . As a result, the CPU 31 that is originally provided for detecting the state of the steel wire rope W is used to detect the state of the detection coil 22 based on the change in the voltage level of the offset voltage applied to the signal receiving end 30a of the receiving circuit 30. Open faults and short-circuit faults can be detected. As a result, it is not necessary to separately provide a dedicated circuit for detecting a failure (open failure and short-circuit failure) of the detection coil 22, and thus a circuit configuration for detecting failure (open failure and short-circuit failure) of the detection coil 22 is provided. Complexity can be suppressed.

  In the present embodiment, as described above, the absolute value of the voltage value of the offset voltage is set to be larger than 差分 of the difference between the maximum value and the minimum value of the detection signal generated from the detection coil 22. The inspection device 100 is configured. Here, the receiving circuit 30 receives a voltage signal obtained by adding a detection signal (AC voltage signal) generated from the detection coil 22 to the offset voltage. Therefore, since the absolute value of the voltage value of the offset voltage is larger than 1/2 of the difference between the maximum value and the minimum value of the detection signal generated from the detection coil 22, the voltage signal obtained by adding the detection signal to the offset voltage Can be easily set to a range of only one of the positive voltage and the negative voltage.

  Further, in the present embodiment, as described above, the inspection device 100 is configured such that each of the receiving circuit 30 and the CPU 31 operates only with a positive voltage. Thus, the receiving circuit 30 and the CPU 31 can be configured with elements driven only by the positive voltage. As a result, the configuration of each of the receiving circuit 30 and the CPU 31 can be simplified as compared with the case where each of the receiving circuit 30 and the CPU 31 is configured by an element driven by both a positive voltage and a negative voltage.

  Further, in the present embodiment, as described above, the offset voltage applying unit 4 divides the voltage value of the DC power supply 5 based on the resistance values of the resistance element 40, the resistance element 41, and the detection coil 22. Thus, the inspection apparatus 100 is configured to apply an offset voltage to the signal receiving end 30a of the receiving circuit 30. Thus, the offset voltage can be applied only by adding a relatively simple configuration such as the resistance element 40 and the resistance element 41 to the existing circuit configuration. As a result, it is possible to effectively suppress the complexity of a circuit configuration for detecting a failure (open-circuit failure and short-circuit failure) of the detection coil 22.

  Further, in the present embodiment, as described above, the receiving circuit 30 detects the voltage of the excitation coil end 21 a of the excitation coil 21, and the CPU 31 determines the excitation coil end caused by the excitation AC current flowing through the excitation coil 21. The inspection device 100 is configured to detect an open failure and a short circuit failure of the excitation coil 21 based on a change in the voltage of the excitation coil 21a. Accordingly, a dedicated circuit for detecting a failure (open failure and short-circuit failure) of the excitation coil 21 by detecting an open failure and a short-circuit failure of the excitation coil 21 based on a change in the voltage level of the excitation coil end 21a. It is possible to detect an open failure and a short-circuit failure of the excitation coil 21 without providing them separately. As a result, it is possible to suppress a complicated circuit configuration for detecting a failure (open failure and short-circuit failure) of the excitation coil 21.

  Further, in the present embodiment, as described above, the CPU 31 detects the open failure and the short-circuit failure of the excitation coil 21 based on the change in the voltage of the excitation coil end 21a due to the turning on and off of the bipolar transistor 33. And the inspection apparatus 100. As a result, the voltage of the excitation coil end 21a can be changed only by providing the bipolar transistor 33, so that the voltage of the excitation coil end 21a is changed by providing a relatively complicated circuit such as an AC voltage source. Further, the complexity of the circuit configuration can be further suppressed.

[Modification]
It should be understood that the embodiments disclosed this time are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description of the embodiments, and includes all equivalents (modifications) within the scope and meaning equivalent to the claims.

  For example, in the above-described embodiment, an example is described in which the offset voltage applying unit 4 is configured by two resistance elements, but the present invention is not limited to this. For example, as shown in FIG. 6, the offset voltage applying section 14 includes a resistance element 40 and a resistance element section 42 including a resistance element 42a, a resistance element 42b, and a resistance element 42c. In FIG. 6, one end of the resistor 42a is connected to the DC power supply 5, and the other end of the resistor 42a is connected to one end of the resistor 42b. The other end of the resistance element 42b is grounded. One end of the resistance element 42c is connected to the signal receiving end 30a, and the other end of the resistance element 42c is connected to the other end of the resistance element 42a (an end opposite to the end to which the DC power supply 5 is connected). ) And one end (the end opposite to the grounded end) of the resistance element 42b. The resistance element section 42 is an example of the “second resistance element section” in the claims.

  Further, in the above embodiment, the example in which the offset voltage applying unit 4 is configured by two resistance elements has been described, but the present invention is not limited to this. For example, as shown in FIG. 7, the offset voltage applying section 24 includes a resistance element section 43 having a Zener diode 43b. Specifically, the offset voltage applying unit 24 includes a resistance element 40 and a resistance element unit 43 including a resistance element 43a, a Zener diode 43b, and a resistance element 43c. In FIG. 7, one end of the resistance element 43a is connected to the DC power supply 5, and the other end of the resistance element 43a is connected to the cathode of the Zener diode 43b. The anode of the Zener diode 43b is grounded. One end of the resistance element 43c is connected to the signal receiving end 30a, and the other end of the resistance element 43c is connected to the other end of the resistance element 43a (an end opposite to the end to which the DC power supply 5 is connected). ) And the cathode of the Zener diode 43b. The resistance element section 43 is an example of the “second resistance element section” in the claims.

  Here, when the resistance element section 43 is composed of only a resistance element, spike noise of a power supply or the like affects the detection result. Therefore, since the resistance element portion 43 has the Zener diode 43b, the Zener diode has a high constant voltage characteristic in a predetermined voltage band (it is hardly affected by spike noise), so that the spike noise affects the detection result. Can be suppressed.

  Further, in the above-described embodiment, an example has been described in which each of the signal receiving unit (receiving circuit 30) and the control unit (CPU 31) is configured to operate only with a positive voltage, but the present invention is not limited to this. Absent. For example, each of the signal receiving unit (receiving circuit 30) and the control unit (CPU 31) may be configured to operate only with a negative voltage.

  Further, in the above-described embodiment, an example has been described in which the excitation AC current is generated in the excitation coil 21 by turning on / off the transistor (bipolar transistor 33), but the present invention is not limited to this. For example, an excitation AC current may be generated in the excitation coil 21 by providing an AC voltage source.

  Further, in the above embodiment, the example in which the bipolar transistor (33) is used as the transistor has been described, but the present invention is not limited to this. For example, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) may be used as the transistor.

  Further, in the above-described embodiment, the example in which the excitation coil (21) is provided in the magnetic body inspection apparatus (the inspection apparatus 100) has been described, but the present invention is not limited to this. For example, the magnetic body inspection apparatus (inspection apparatus 100) may not include the excitation coil (21).

  Further, in the above-described embodiment, an example in which the magnetic body inspection apparatus (inspection apparatus 100) is used to inspect a magnetic body (steel wire rope W) built in the mobile X-ray imaging apparatus (900). Although shown, the invention is not limited to this. For example, the magnetic device inspection device (the inspection device 100) may be used to inspect a wire used for a crane, an elevator, a suspension bridge, a robot, or the like. Further, a magnetic body other than a wire may be inspected by a magnetic body inspection apparatus.

  Further, in the above embodiment, the example in which the AD converter is provided in the control unit (CPU 31) has been described, but the present invention is not limited to this. For example, the AD converter may be provided in the signal receiving unit (receiving circuit 30).

  Further, in the above-described embodiment, an example of the configuration in which the resistance element (102) is provided between the excitation coil (21) and the DC power supply (5) has been described, but the present invention is not limited to this. For example, as shown in FIG. 8, the excitation coil 21 and the DC power supply 5 may be directly connected. In this case, the receiving circuit 30 detects (receives) the voltage of the excitation coil end 21b between the excitation coil 21 and the bipolar transistor 33. In FIG. 8, components that are not necessary for description are not shown for simplicity.

  Further, in the above embodiment, an example is described in which the control unit (CPU 31) detects both an open failure and a short-circuit failure of the differential coil (detection coil 22), but the present invention is not limited to this. For example, the control unit (CPU 31) may detect any one of an open failure and a short-circuit failure of the differential coil (detection coil 22).

  Further, in the above embodiment, an example is described in which the control unit (CPU 31) detects both an open failure and a short-circuit failure of the excitation coil (21), but the present invention is not limited to this. For example, the control unit (CPU 31) may detect one of an open failure and a short-circuit failure of the excitation coil (21).

4, 14, 24 Offset voltage applying unit 5 DC power supply 21 Exciting coil 21a, 21b Exciting coil end 22 Detection coil (differential coil)
30 receiver circuit (signal receiver)
30a signal receiving end 31 CPU (control unit)
33 Bipolar transistor (transistor)
40 resistance element (first resistance element section)
41 resistance element (second resistance element section)
42, 43 resistance element part (second resistance element part)
43b Zener diode 100 Detector (Detector for magnetic material)
W steel wire rope (magnetic material)

Claims (7)

A differential coil that detects a change in the magnetic field of the magnetic body to be inspected and outputs a detection signal;
A signal receiving unit that receives the detection signal output from the differential coil,
A control unit that detects a state of the magnetic body based on a signal from the signal receiving unit,
An offset voltage applying unit that is provided between the differential coil and the signal receiving unit and applies an offset voltage to a signal receiving end of the signal receiving unit.
The magnetic body inspection device, wherein the control unit is configured to detect at least one of an open failure and a short circuit failure of the differential coil based on a change in a voltage level of the offset voltage.   2. The magnetic body inspection device according to claim 1, wherein an absolute value of a voltage value of the offset voltage is larger than １ ／ of a difference between a maximum value and a minimum value of the detection signal generated from the differential coil.   3. The magnetic body inspection device according to claim 2, wherein each of the signal receiving unit and the control unit is configured to operate by one of a positive voltage and a negative voltage. 4.   The offset voltage applying unit includes a first resistive element provided between the differential coil and the signal receiving end, and a second resistive element provided between the DC power supply and the signal receiving end. And dividing the voltage value of the DC power supply based on the resistance value of each of the first resistance element section, the second resistance element section, and the differential coil, so that the signal reception of the signal reception section is performed. The inspection apparatus for a magnetic body according to claim 1, wherein the apparatus is configured to apply the offset voltage to an end.   The inspection device for a magnetic body according to claim 4, wherein the second resistance element unit has a Zener diode. Further comprising an excitation coil for exciting the state of magnetization of the magnetic material,
The signal receiving unit detects a voltage at an excitation coil end of the excitation coil,
The control unit detects at least one of an open failure and a short-circuit failure of the excitation coil based on a change in voltage at the excitation coil end caused by an excitation AC current flowing through the excitation coil. The inspection device for a magnetic body according to claim 1, wherein the inspection device is configured. A DC power supply is connected to one side of the excitation coil, and a transistor that is turned on and off based on a signal from the control unit is connected to the other side of the excitation coil,
The control unit is configured to detect at least one of an open failure and a short-circuit failure of the excitation coil based on a change in voltage of the excitation coil end caused by turning on / off of the transistor. An inspection apparatus for a magnetic body according to claim 6.

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