Detection of Magnetic Pulse and Direction during Magnetization

Abstract

Disclosed is a magnetization pulse detector for detecting a magnetization pulse generated by a magnetization coil, the magnetization pulse detector comprising: a measurement coil configured to generate a measurement pulse in response to the magnetization pulse generated by the magnetization coil; a measurement pulse detection circuit configured to generate a detection signal based on the measurement pulse generated by the measurement coil; and a duration extension circuit configured to generate an extended detection signal based on the detection signal generated by the measurement pulse detection circuit.

Description

Technical Field

[0001] The present disclosure relates to magnetization devices and detectors, and more particularly to detection devices for detecting magnetization pulses and one or more parameters.

Background Art

[0002] When magnetizing a material with an electric pulse, it may be important to know the direction of pulse propagation. This is important even if there is a device that can indicate how to discharge the pulse during magnetization. When the magnetization device is part of a large-scale production facility, it may be important to know the direction of the magnetic field of the magnet and to verify that the device has completed the magnetization process. This can be difficult. This is because the pulses used in the process are usually not long enough to be detected individually.

[0003] When generating a current using a magnetization pulse, the pulse is typically at an intensity level exceeding 50 volts and is measured in microseconds. This short pulse duration and high intensity make it difficult to read the magnetization pulse. When using current for information, usually, when the voltage is high, the pulse duration is made long, and when the pulse duration is short, it is in a low voltage range (for example, 3 to 5 volts). Current solutions for measuring magnetization pulses are expensive and complex to introduce into a production line. This means that it is costly and difficult to introduce the current solutions on the market into multiple mass production lines, combined with the desire to introduce a robust and easily maintainable solution into the production line.

[0004] It would be desirable to have a relatively inexpensive and robust system and method for detecting and verifying the magnetization process.

Summary of the Invention

[0005] A magnetization pulse detector for detecting a magnetization pulse generated by a magnetization coil is disclosed. Here, the magnetization pulse detector includes a measurement coil, a measurement pulse detection circuit, and a duration extension circuit. The measurement coil is configured to generate a measurement pulse in response to the magnetization pulse generated by the magnetization coil. The measurement pulse detection circuit is configured to generate a detection signal based on the measurement pulse generated by the measurement coil. The duration extension circuit is configured to generate an extended detection signal based on the detection signal generated by the measurement pulse detection circuit. The measurement coil may be housed in a first housing, and the measurement pulse detection circuit and the duration extension circuit may be housed in a second housing.

[0006] The measurement pulse detection circuit may include a plurality of Zener diodes connected in parallel with each other and connected in parallel with the measurement coil. Each of the Zener diodes may have a Zener voltage of 24 volts. The measurement pulse detection circuit may include a rectifier diode, the cathode of the rectifier diode being coupled to either the positive or negative side of the measurement coil, and the anode of the rectifier diode being coupled to the anodes of the plurality of Zener diodes connected in parallel.

[0007] The duration extension circuit may be configured to trigger only when the detection signal exceeds a pulse threshold indicating that the magnetization pulse generated by the magnetization coil was sufficient to successfully magnetize the object under inspection. The duration extension circuit may include a detection signal holding relay configured to hold the detection signal until it is reset by a reset signal. The detection signal holding relay may be a solid state relay configured to trigger only when the detection signal exceeds a pulse threshold indicating that the magnetization pulse generated by the magnetization coil was sufficient to successfully magnetize the object under inspection.

[0008] The measurement pulse detection circuit may include a first measurement pulse smoothing unit and a second measurement pulse smoothing unit configured to smooth the vibration of the measurement pulse, and a steering unit configured to guide a negative polarity measurement pulse to the first measurement pulse smoothing unit and a positive polarity measurement pulse to the second measurement pulse smoothing unit. The first measurement pulse smoothing unit may generate a negative polarity detection signal when the negative polarity measurement pulse is guided to the first measurement pulse smoothing unit, and the second measurement pulse smoothing unit may generate a positive polarity detection signal when the positive polarity measurement pulse is guided to the second measurement pulse smoothing unit.

[0009] The steering unit may include first and second rectifying diodes. The cathode of the first rectifying diode may be connected to the positive electrode side of the measurement coil, allowing the negative polarity measurement pulse to pass through the first measurement pulse smoothing unit and blocking the positive polarity measurement pulse. The cathode of the second rectifying diode may be connected to the negative electrode side of the measurement coil, allowing the positive polarity measurement pulse to pass through the second measurement pulse smoothing unit and blocking the negative polarity measurement pulse.

[0010] The first measurement pulse smoothing unit may include a set of a plurality of first Zener diodes connected in parallel, and the second measurement pulse smoothing unit may include a set of a plurality of second Zener diodes connected in parallel. The anode of the first rectifying diode may be connected to the anodes of the plurality of first Zener diodes, and the anode of the second rectifying diode may be connected to the anodes of the plurality of second Zener diodes. The measurement coil may be housed in a first housing, the measurement pulse detection circuit and the duration extension circuit may be housed in a second housing, and an interconnecting cable may connect the first and second housings. The interconnecting cable may include a first line configured to couple the positive electrode side of the measurement coil to the cathode of the first rectifying diode, a second line configured to couple the negative electrode side of the measurement coil to the cathode of the second rectifying diode, and a cable screen configured to couple to a safety ground.

[0011] The duration extension circuit may include a negative polarity pulse detection circuit configured to be triggered based on the negative polarity detection signal and a positive polarity pulse detection circuit configured to be triggered based on the positive polarity detection signal. The negative polarity pulse detection circuit may be configured to trigger only when the negative polarity detection signal exceeds a negative pulse threshold value indicating that the magnetization pulse generated by the magnetization coil was sufficient to successfully magnetize the test object with negative polarity. The positive polarity pulse detection circuit may be configured to trigger only when the positive polarity detection signal exceeds a positive pulse threshold value indicating that the magnetization pulse generated by the magnetization coil was sufficient to successfully magnetize the test object with positive polarity. The negative polarity pulse detection circuit may include a negative polarity pulse detection holding relay configured to hold the extension detection signal until it is reset by a reset signal. The positive polarity pulse detection circuit may include a positive polarity pulse detection holding relay configured to hold the extension detection signal until it is reset by the reset signal. The negative polarity pulse detection holding relay and the positive polarity pulse detection holding relay may be solid state relays. The reset signal may be generated outside the duration extension circuit.

Brief Description of the Drawings

[0012] The above aspects of the present disclosure and the methods for obtaining them will become clearer by referring to the following description of the embodiments of the present disclosure understood in conjunction with the accompanying drawings, and the present disclosure itself will be better understood.

Figure 1

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[0013] The embodiments of the present disclosure described below are not intended to be exhaustive or to limit the present disclosure to the exact forms in the following detailed description. Rather, the embodiments are selected and described so that those skilled in the art can recognize and understand the principles and practices of the present disclosure.

[0014] There is a magnetization device for magnetizing a small isotropic (unmagnetized) magnet in an arbitrary direction. The magnetization device may include a control unit having a large-capacity power supply and a bank of large-capacity capacitors. When the magnetization device operates, the power supply charges the capacitors, and the capacitors can discharge the charge to the magnetization coil through thick-gauge wires. The energy can be made very high, such as 2100 volts and 5000 amperes, and the duration can be made very short, such as 300 microseconds (μsec). It is desirable to be able to determine whether the magnetization process was successfully performed and in which polarity direction it was executed. The control unit does not provide reliable feedback on these parameters. There is no off-the-shelf sensor or detector that can detect this very short-duration magnetization pulse and know the direction in a simple way. The detection device is desirably a simple and low-cost device that does not require a computer or a very sophisticated system, such as a Helmholtz coil measurement system. The detection device is desired to detect a magnetization pulse of short duration, effectively extend its duration to make the magnetization pulse easier to detect, verify that the magnetization process of the material was successfully performed, and identify the direction / polarity of the generated magnetic field.

[0015] Figure 1 shows a magnetization device 10 and a magnetization pulse detector 20. The magnetization device 10 includes a magnetization coil 12 and a control unit 14. Arrows 16, 18 indicate the magnetic field axes of the positive and negative polarity magnetization pulses generated by the magnetization coil 12. The magnetization pulse detector 20 includes a measurement coil 22 and a pulse detection circuit 24 configured to verify and measure the parameters of the magnetization pulse generated by the magnetization coil 12 and provide a detector output 28. The magnetization coil 12 may be a Helmholtz coil. The magnetization coil 12 can generate a magnetization pulse, thereby generating a current in the measurement coil 22. The strength of the current generated by the magnetization pulse can be determined by the number of turns of the measurement coil 22, for example, 4 to 20 turns of copper wire. If the strength of the current is too strong, there is a risk of burning the connected circuit board.

[0016] The diameter of the measurement coil 22 may be the same as that of the magnetization coil 12, and the measurement coil 22 may be arranged near the magnetization coil 12 along its magnetic field axis. By connecting the measurement coil 22 to an oscilloscope, the induced amount picked up by the measurement coil 22 when a magnetization pulse is generated by the magnetization coil 12 can be measured. For example, a measurement coil wound 27 times with a standard 0.8 millimeter (mm) insulated copper wire provided an oscilloscope reading of a positive polarity pulse lasting about 300 microseconds (μsec) at about 100 volts. When the polarity of magnetization was reversed, the measurement coil provided an oscilloscope reading of a negative polarity pulse of about 100 volts and about 300 μsec on the oscilloscope. However, these pulses on the oscilloscope had some unwanted oscillations often seen when a rapid input rise was applied to the coil. This is often called the step response, and the oscillations or ringing had an amplitude of about 60 volts peak-to-peak and a frequency of about 100 KHz.

[0017] To generate a cleaner signal, it may be desirable to smooth the measurement pulse by reducing the oscillation or ringing of the pulse provided by the measurement coil 22. To reduce this ringing, a resistor can be added in parallel with the measurement coil 22, but the parallel resistor can reduce the pulse. Alternatively, a capacitor can be added in parallel with the measurement coil 22 to flatten the ringing oscillation and can be somewhat efficient if there is no need to regulate the magnetizing force.

[0018] The Zener diode can be arranged in parallel with the measuring coil 22 with the cathode of the Zener diode facing the direction of the conductor of the positive pole of the measuring coil 22. When magnetizing with reverse polarity, reverse the direction of the Zener diode. The Zener diode can have a Zener voltage of 24 volts for compatibility with standard automation equipment. The Zener series impedance of the Zener diode (e.g., 14 ohms (Ω)) shorts the measuring coil 22 until the voltage becomes lower than a specific Zener voltage (e.g., 24 volts). In the test, one Zener diode placed in parallel with the measuring coil 22 burned out after several trials. This is because the resistance was low and the voltage could not be lowered to the maximum rated allowable level. To pull down to the required maximum voltage of 24 volts, less resistance and voltage were needed, and to create a more reliable circuit, a greater current handling capacity was required.

[0019] As shown in FIG. 2, when a plurality of Zener diodes 202 are connected in parallel with the measuring coil 22, the current handling capacity is increased several times. For example, when six Zener diodes with a Zener voltage of 24 volts and a Zener series impedance of 14 Ω are connected in parallel with each other and then connected to the measuring coil 22, a greater current handling capacity and a Zener series impedance of 2.33 Ω can be obtained. Also, by reducing the number of turns of the measuring coil 22, the stress on the Zener diode can be further reduced. For example, when the number of turns of the measuring coil 22 is reduced to 4 times, the measuring pulse voltage can be decreased, the current can be suppressed to a level that the Zener diode 202 can handle, and it can be ensured that the measuring pulse voltage stays within the window corresponding to the magnetizing force of 60 - 100% (e.g., 23 - 30 volts).

[0020] The magnetization pulse measurement device 20 desirably detects the magnetization pulse of the magnetization coil 12 regardless of its polarity. FIG. 3 shows an exemplary embodiment of a magnetization pulse measurement device having a first bank 320 of parallel Zener diodes, a second bank 340 of parallel Zener diodes, a first rectifying diode 330, and a second rectifying diode 350. The positive electrode side of the measurement coil 22 is connected to the anode of the first bank 320 of Zener diodes via the first rectifying diode 330, and the negative electrode side of the measurement coil 22 is connected to the cathode of the first bank 320 of Zener diodes. The negative electrode side of the measurement coil 22 is connected to the anode of the second bank 340 of Zener diodes via the second rectifying diode 350, and the Positive electrode side is connected to the Cathode of the second bank 340 of Zener diodes. The first and second rectifying diodes 330, 350 may be ultra-fast rectifying diodes capable of handling high current and high voltage. As shown in FIG. 3, the two rectifying diodes 330, 350 are attached in front of the two banks 320, 340 of Zener diodes to direct the measurement pulse generated by the measurement coil 22 to one or the other of the first and second banks 320, 340 of Zener diodes according to the polarity of the measurement pulse. When a positive-polarity magnetization pulse is generated by the magnetization coil 12, the measurement coil 22 picks up the positive-polarity pulse that the first rectifying diode 330 blocks and the second rectifying diode 350 passes to the second bank 340 of Zener diodes, and generates a positive-polarity detection signal on the positive-polarity output line 342. When a negative-polarity magnetization pulse is generated by the magnetization coil 12, the measurement coil 22 picks up the negative-polarity pulse that the first rectifying diode 330 passes to the first bank 320 of Zener diodes and the second rectifying diode 350 blocks, and the first bank 320 of Zener diodes generates a negative-polarity detection signal on the negative-polarity output line 322.

[0021] It may be desirable to extend the duration of the signals on output lines 322, 342 so that they can be picked up by the controller and to ensure compatibility with the I / O interface of the controller. A pulse duration of 300 μsec is too fast for a typical programmable logic controller (PLC) to pick up. A PLC typically requires a pulse duration of about 500 μsec. This is because short on-signals generated by short-duration pulses may be missed during the scan time in the PLC's program routine. Since a mechanical relay typically requires about 20 msec, this pulse duration may not even be sufficient time to turn on a mechanical relay. A solid-state relay has no moving parts and is typically an optoelectronic device that can be turned on in as little as 20 μsec, which is fast enough to reliably detect the positive and negative polarity detection signals on output lines 322, 342. It may also be desirable to electrically insulate the controller from the magnetization pulse measuring device 20.

[0022] To enable the PLC to reliably detect the positive and negative polarity detection signals on output lines 322, 342, a plurality of solid-state relays can be used after the first and second banks 320, 340 of zener diodes. FIG. 4 shows an exemplary embodiment having three solid-state relays 420 - 424 on the negative-polarity output line 322 after the first bank 320 of zener diodes and three solid-state relays 440 - 442 on the positive-polarity output line 342 after the second bank 340 of zener diodes.

[0023] For the first set of relays 420 - 424, the first solid - state relay 420 can function as a trigger to the second solid - state relay 422. The second solid - state relay 422 can generate a holding function. The third solid - state relay 424 can send an electrically isolated on - signal to the PLC on the negative - pulse detection line 428. For the second set of relays 440 - 444, the first solid - state relay 440 can function as a trigger to the second solid - state relay 442. The second solid - state relay 442 can generate a holding function. The third solid - state relay 444 can send an electrically isolated on - signal to the PLC on the positive - pulse detection line 448. The holding functions of these second solid - state relays 422, 442 remain on until a reset signal terminates the closed - loop of the holding function. The PLC may include a reset relay 450 that is triggered by an output from the PLC. When the PLC triggers the reset relay 450, a reset signal is sent from the reset relay 450, and the closed - loop of the holding function of the first set of solid - state relays 420 - 424 or the second set of solid - state relays 440 - 444 ends. Thereby, the PLC ensures all the time necessary to register the result regardless of the direction of the polarity, and when ready, sends a reset signal back to the magnetization - pulse detector 20, thereby enabling the magnetization - pulse detector 20 to be ready for a new detection.

[0024] Figure 4 shows the negative output line 322 coupled to the trigger solid state relay 420. The negative output line 322 may also be coupled to the negative test output line 402. The trigger solid state relay 420 is coupled to the holding solid state relay 422 and triggers the negative / reverse output holding function on the holding solid state relay 422 when a negative detection signal is detected on the negative output line 322. The holding solid state relay 422 is coupled to the output solid state relay 424, where an electrically isolated output signal or on signal can indicate the negative detection signal to the PLC on the negative pulse detection line 428. The normally closed contact 450 can be opened to interrupt the self-holding function of the trigger solid state relay 420 on the holding solid state relay 422.

[0025] Figure 4 also shows the positive output line 342 coupled to the trigger solid state relay 440. The positive output line 342 may also be coupled to the positive test output line 404. The trigger solid state relay 440 is coupled to the holding solid state relay 442 and triggers the positive / direct output holding function on the holding solid state relay 442 when a positive detection signal is detected on the positive output line 342. The holding solid state relay 442 is coupled to the output solid state relay 444, where an electrically isolated output signal or on signal can indicate the positive detection signal to the PLC on the positive pulse detection line 448. The normally closed contact 452 can be opened to interrupt the self-holding function of the trigger solid state relay 440 on the holding solid state relay 442.

[0026] An external input (e.g., 24V input) may be provided for the electrically insulated negative and positive outputs on the pulse detection lines 428, 448. The contacts 450, 452 that can interrupt the self-holding function may be connected together such that when either contact is triggered to open, both contacts 450 and 452 are triggered to open. The contacts 450, 452 can have various embodiments, such as a manual button, an externally actuated relay, a time-limited reset, etc.

[0027] The turn-on thresholds of the solid-state relays 420 - 424, 440 - 444 can also be utilized to verify whether the magnetization by the magnetization coil 12 of the magnetization device 10 has been successful. For example, if the solid-state relay has a turn-on threshold of 17 volts, the solid-state relay will not turn on if the measurement pulse from the measurement coil 22 is less than 17 volts. The magnetizing force required to reach this turn-on threshold can be determined, and the circuit of the magnetization pulse detector 20 is configured to require a measurement pulse sufficient to reach this turn-on threshold. For example, when it is determined that the test object cannot be successfully magnetized with a magnetizing force of 40% or less and the turn-on thresholds for the solid-state relays 420 - 424, 440 - 444 require at least 52% of the magnetizing force. In this case, only the magnetizing force sufficient to successfully magnetize the test object will turn on the solid-state relays 420 - 424, 440 - 444.

[0028] Since the inductive energy of the measurement coil 22 may increase, it may be desirable to separate the measurement coil 22 from the pulse detection circuit 24. FIG. 5 shows a magnetization device 10 and an exemplary magnetization pulse detector 20 in which the measurement coil 22 is separately housed from the rest of the pulse detection circuit 24 and the measurement coil 22 is connected to the rest of the pulse detection circuit 24 using a screened 3-pin XLR interconnect cable 500. The 3-pin XLR interconnect cable 500 includes a first line 502 that couples the positive side of the measurement coil 22 to the first rectifier diode 330, a second line 504 that couples the negative side of the measurement coil 22 to the second rectifier diode 350, and a third line 506 that serves as a cable screen and is connected to a safety ground (PE) to release energy in the event that the cable 500 is damaged. The XLR interconnect cable 500 also provides the possibility of creating a safe end upon cutting by using the end of the female XLR connector where there may be voltage. As long as the Zener circuits 320, 340 are connected to the measurement coil 22, dangerous voltages will not be reached. However, if the XLR interconnect cable 500 is disconnected from the Zener circuits 320, 340, the voltage can reach up to 60 volts. The risk of electric shock can be reduced by using the female XLR connector in the housing of the measurement coil 22 for connection by means of the male XLR connector at that end of the XLR interconnect cable 500.

[0029] Although the present disclosure has been illustrated and described in detail in the drawings and the foregoing description, such illustrations and descriptions are considered to be exemplary and not limiting of the features, exemplary embodiments(s) have been illustrated and described, and it is understood that all changes and modifications within the spirit of the present disclosure are desired to be protected. It should be noted that alternative embodiments of the present disclosure may not include all of the features described, but may still benefit from at least some of the advantages of such features. Those skilled in the art can readily devise unique implementations that incorporate one or more of the features of the present disclosure and fall within the spirit and scope of the invention as defined by the appended claims.

Claims

1. A magnetization pulse detector for detecting a magnetization pulse generated by a magnetization coil, comprising: a measurement coil configured to generate a measurement pulse in response to the magnetization pulse generated by the magnetization coil; a measurement pulse detection circuit configured to generate a detection signal based on the measurement pulse generated by the measurement coil; a duration extension circuit configured to generate an extended detection signal based on the detection signal generated by the measurement pulse detection circuit; the measurement pulse detection circuit includes a plurality of Zener diodes connected in parallel with each other and connected in parallel with the measurement coil; the duration extension circuit is configured to trigger only when the detection signal exceeds a pulse threshold indicating that the magnetization pulse generated by the magnetization coil was sufficient to successfully magnetize the object under inspection. A magnetization pulse detector.

2. The magnetization pulse detector according to claim 1, wherein each of the Zener diodes of the plurality of Zener diodes has a Zener voltage of 24 volts.

3. The measurement pulse detection circuit further includes a rectifier diode, the cathode of the rectifier diode is coupled to one of the positive and negative sides of the measurement coil, The magnetization pulse detector according to claim 1 or 2, wherein the anode of the rectifier diode is coupled to the anodes of the plurality of Zener diodes connected in parallel.

4. The magnetization pulse detector according to any one of claims 1 to 3, wherein the duration extension circuit includes a detection signal holding relay configured to hold the detection signal until it is reset by a reset signal.

5. A magnetization pulse detector for detecting a magnetization pulse generated by a magnetization coil, comprising: a measurement coil configured to generate a measurement pulse in response to the magnetization pulse generated by the magnetization coil; a measurement pulse detection circuit configured to generate a detection signal based on the measurement pulse generated by the measurement coil; a duration extension circuit configured to generate an extended detection signal based on the detection signal generated by the measurement pulse detection circuit; the duration extension circuit includes a detection signal holding relay configured to hold the detection signal until it is reset by a reset signal. The detection signal holding relay is a solid-state relay configured to trigger only when the detection signal exceeds a pulse threshold indicating that the magnetization pulse generated by the magnetization coil was sufficient to successfully magnetize the object under inspection, which is a magnetization pulse detector. **Claim 6**: A magnetization pulse detector for detecting a magnetization pulse generated by a magnetization coil, a measurement coil configured to generate a measurement pulse in response to the magnetization pulse generated by the magnetization coil, a measurement pulse detection circuit configured to generate a detection signal based on the measurement pulse generated by the measurement coil, a duration extension circuit configured to generate an extended detection signal based on the detection signal generated by the measurement pulse detection circuit, comprising: the measurement pulse detection circuit includes a plurality of Zener diodes connected in parallel with each other and in parallel with the measurement coil, the measurement pulse detection circuit further includes a rectifier diode, the cathode of the rectifier diode is coupled to one of the positive and negative electrodes of the measurement coil, the anode of the rectifier diode is coupled to the anodes of the plurality of Zener diodes connected in parallel, the duration extension circuit includes a detection signal holding relay configured to hold the detection signal until reset by a reset signal, the detection signal holding relay is a solid-state relay configured to trigger only when the detection signal exceeds a pulse threshold indicating that the magnetization pulse generated by the magnetization coil was sufficient to successfully magnetize the object under inspection, which is a magnetization pulse detector. **Claim 7** the measurement coil is housed in a first housing, the magnetization pulse detector according to any one of claims 1 to 6, wherein the measurement pulse detection circuit and the duration extension circuit are housed in a second housing. **Claim 8** the measurement pulse detection circuit a first measurement pulse smoothing section configured to smooth the oscillation of the measurement pulse, a second measurement pulse smoothing section configured to smooth the oscillation of the measurement pulse, and a steering section configured to direct a negative-polarity measurement pulse to the first measurement pulse smoothing section and a positive-polarity measurement pulse to the second measurement pulse smoothing section. The first measurement pulse smoothing unit generates a negative polarity detection signal when the negative polarity measurement pulse is led to the first measurement pulse smoothing unit. The magnetization pulse detector according to any one of claims 1 to 7, wherein the second measurement pulse smoothing unit generates a positive polarity detection signal when the positive polarity measurement pulse is led to the second measurement pulse smoothing unit.

9. The steering unit includes first and second rectifying diodes. The cathode of the first rectifying diode is connected to the positive electrode side of the measurement coil, passes the negative polarity measurement pulse to the first measurement pulse smoothing unit, and blocks the positive polarity measurement pulse. The magnetization pulse detector according to claim 8, wherein the cathode of the second rectifying diode is connected to the negative electrode side of the measurement coil, passes the positive polarity measurement pulse to the second measurement pulse smoothing unit, and blocks the negative polarity measurement pulse.

10. A magnetization pulse detector that detects a magnetization pulse generated by a magnetization coil, a measurement coil configured to generate a measurement pulse in response to the magnetization pulse generated by the magnetization coil, a measurement pulse detection circuit configured to generate a detection signal based on the measurement pulse generated by the measurement coil, and a duration extension circuit configured to generate an extended detection signal based on the detection signal generated by the measurement pulse detection circuit. The measurement pulse detection circuit includes a first measurement pulse smoothing unit configured to smooth the oscillation of the measurement pulse, a second measurement pulse smoothing unit configured to smooth the oscillation of the measurement pulse, and a steering unit configured to lead the negative polarity measurement pulse to the first measurement pulse smoothing unit and lead the positive polarity measurement pulse to the second measurement pulse smoothing unit. The first measurement pulse smoothing unit generates a negative polarity detection signal when the negative polarity measurement pulse is led to the first measurement pulse smoothing unit. The second measurement pulse smoothing unit generates a positive polarity detection signal when the positive polarity measurement pulse is led to the second measurement pulse smoothing unit. The steering unit includes first and second rectifying diodes. The cathode of the first rectifying diode is connected to the positive electrode side of the measurement coil, passes the negative polarity measurement pulse to the first measurement pulse smoothing unit, and blocks the positive polarity measurement pulse. The cathode of the second rectifying diode is connected to the negative electrode side of the measurement coil, passing a positive-polarity measurement pulse through the second measurement pulse smoothing section and blocking a negative-polarity measurement pulse. The first measurement pulse smoothing section includes a plurality of first Zener diodes connected in parallel. The second measurement pulse smoothing section includes a plurality of second Zener diodes connected in parallel. The anode of the first rectifying diode is connected to the anodes of the plurality of first Zener diodes. The anode of the second rectifying diode is connected to the anodes of the plurality of second Zener diodes, which is a magnetization pulse detector.

11. The measurement coil is housed in a first housing. The measurement pulse detection circuit and the duration extension circuit are housed in a second housing. The interconnecting cable connects the first and second housings. The interconnecting cable A first line configured to couple the positive electrode side of the measurement coil to the cathode of the first rectifying diode; A second line configured to couple the negative electrode side of the measurement coil to the cathode of the second rectifying diode; The magnetization pulse detector according to claim 9 or 10, comprising a cable screen configured to be coupled to a safety ground.

12. A magnetization pulse detector for detecting a magnetization pulse generated by a magnetization coil, comprising: A measurement coil configured to generate a measurement pulse in response to the magnetization pulse generated by the magnetization coil; A measurement pulse detection circuit configured to generate a detection signal based on the measurement pulse generated by the measurement coil; A duration extension circuit configured to generate an extended detection signal based on the detection signal generated by the measurement pulse detection circuit, The duration extension circuit A negative pulse detection circuit configured to be triggered based on a negative-polarity detection signal; A positive pulse detection circuit configured to be triggered based on a positive-polarity detection signal, which is a magnetization pulse detector.

13. A magnetization pulse detector for detecting a magnetization pulse generated by a magnetization coil, comprising: A measurement coil configured to generate a measurement pulse in response to the magnetization pulse generated by the magnetization coil; A measurement pulse detection circuit configured to generate a detection signal based on the measurement pulse generated by the measurement coil; A duration extension circuit configured to generate an extended detection signal based on the detection signal generated by the measurement pulse detection circuit, and the measurement pulse detection circuit a first measurement pulse smoothing unit configured to smooth the oscillation of the measurement pulse, a second measurement pulse smoothing unit configured to smooth the oscillation of the measurement pulse, a steering unit configured to guide a negative-polarity measurement pulse to the first measurement pulse smoothing unit and a positive-polarity measurement pulse to the second measurement pulse smoothing unit, the first measurement pulse smoothing unit generates a negative-polarity detection signal when the negative-polarity measurement pulse is guided to the first measurement pulse smoothing unit, the second measurement pulse smoothing unit generates a positive-polarity detection signal when the positive-polarity measurement pulse is guided to the second measurement pulse smoothing unit, the duration extension circuit a negative pulse detection circuit configured to be triggered based on the negative-polarity detection signal, a positive pulse detection circuit configured to be triggered based on the positive-polarity detection signal, the negative pulse detection circuit is configured to trigger only when the negative-polarity detection signal exceeds a negative pulse threshold indicating that the magnetization pulse generated by the magnetization coil is sufficient to successfully magnetize a negative-polarity object under test, the positive pulse detection circuit is configured to trigger only when the positive-polarity detection signal exceeds a positive pulse threshold indicating that the magnetization pulse generated by the magnetization coil is sufficient to successfully magnetize a positive-polarity object under test. A magnetization pulse detector

14. the negative pulse detection circuit includes a negative pulse detection holding relay configured to hold the extended detection signal until it is reset by a reset signal, The magnetization pulse detector according to claim 13, wherein the positive pulse detection circuit includes a positive pulse detection holding relay configured to hold the extended detection signal until it is reset by the reset signal.

15. the negative pulse detection holding relay is a solid-state relay, The magnetization pulse detector according to claim 14, wherein the positive pulse detection holding relay is a solid-state relay.

16. The negative-pulse detection and holding relay is configured to be triggered only when the negative-polarity detection signal exceeds a negative-pulse threshold value indicating that the magnetization pulse generated by the magnetization coil was sufficient to successfully magnetize a negatively polarized object to be inspected. The positive-pulse detection and holding relay is configured to be triggered only when the positive-polarity detection signal exceeds a positive-pulse threshold value indicating that the magnetization pulse generated by the magnetization coil was sufficient to successfully magnetize a positively polarized object to be inspected. The magnetization pulse detector according to claim 14 or 15. **Claim 17** The reset signal is generated outside the duration extension circuit. The magnetization pulse detector according to any one of claims 14 to 16. **Claim 18** The measurement coil is housed in a first housing. The measurement pulse detection circuit and the duration extension circuit are housed in a second housing. The magnetization pulse detector according to any one of claims 8 to 10.

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