JP2006343181A - Magnetic field measurement apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic field measurement apparatus easy to operate and equipped with analog outputting function etc., of effective value to an external apparatus and capable of displaying effective value of each axis in various mode, as well as resultant effective value of the X-axis, Y-axis and Z-axis components. <P>SOLUTION: The magnetic field measurement apparatus for calculating the prescribed parameters of the magnetic field to be measured comprises three coils 11 of X-axis coil 11x, Y-axis coil 11y and Z-axis coil 11z for detecting the magnetic field; the integrator 21 and an A/D converter 24 are at least included in each measurement system of each coil 11; the operation controller 25 for receiving the output voltage of each coil 11 via the integrator 21 and the A/D converter 24 for calculating the prescribed parameters of the magnetic field; and the analogue output part 40 for outputting the analog signal in each coil system 11 to an external apparatus. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magnetic field measuring apparatus, and more particularly to a magnetic field measuring apparatus suitable for measuring a magnetic field radiated from a power transmission system, a home appliance, or the like.

  Magnetic fields (electromagnetic fields) in an extremely wide frequency band are radiated in unspecified directions from household electrical appliances such as power lines, transformers, microwave ovens, and personal computer displays that are in daily contact with the human body. There are concerns about adverse effects on the human body.

  Therefore, the International Commission on Non-Ionizing Radiation Protection (International Commission on Non-Ionizing Radiation Protection; abbreviation ICNIRP) announced in April 1998 that “Guidelines for limiting exposure to time-varying electric and magnetic fields and electromagnetic fields (up to 300 GHz). ) ”, And the guideline provides reference levels for each mode of occupational and public exposure.

  Note that the reference level of the magnetic field in the low frequency region varies greatly depending on the frequency. Therefore, when the magnetic field frequency generated by the electrical device is a wide band, the measured value cannot be directly compared with the reference level. Therefore, in order to be able to collate with the reference level, a method for normalizing the measurement magnetic field to a reference frequency such as 50 Hz or 60 Hz, for example, by a weighting function for the frequency is defined as a standard evaluation method. It is called Time domain evaluation).

In addition, TCO (the latest version of TCO '03FPD), an international integrated standard for the safety, ergonomics, electromagnetic radiation, energy saving, and environment of office equipment under the jurisdiction of TCO Development owned by the Swedish Employers' Federation. A4 emissions; A4.3 AC magnetic field measurement, as a requirement for the monitor screen,
(Low frequency): 5 Hz to 2 kHz; front 30/50 cm, ≦ 200 nT
(High region): 2 kHz to 400 kHz; 30 cm in front and 50 cm in circumference, ≦ 25 nT
Is defined as (units of Tesla, 1 Tesla (T) = 10 ⁴ gauss (G)).

  In addition, for example, MDR and JEITA guideline ITR-3004 also define standards similar to TCO. Among these standards, the reference level indicated in the above-mentioned ICNIRP guidelines (hereinafter referred to as ICNIRP reference level). Patent Document 1 discloses an exposure measurement device that measures the exposure of a magnetic field to be measured based on the above.

  At the reference level of ICNIRP, as an example, the magnetic flux density B (exposure amount) is low in the low frequency range and the high frequency range in the frequency range of 10 Hz to 400 kHz, and is low in the intermediate frequency range. Regardless of whether it is specified to be almost constant.

  Therefore, the exposure amount measuring apparatus described in Patent Document 1 uses an evaluation filter composed of the reciprocal of the reference level of ICNIRP. That is, an output signal having a substantially constant amplitude regardless of the frequency of the magnetic field is obtained by passing a detection signal having an amplitude proportional to the magnetic field strength of the X-axis component, the Y-axis component, and the Z-axis component detected by the magnetic field detection means. The exposure amount is calculated from digital data obtained by A / D converting the output signal.

JP 2001-235396 A

  According to the exposure measuring apparatus described in Patent Document 1, it is possible to measure the exposure based on the reference level of ICNIRP, but the X-axis component, Y-axis component, and Z are displayed as measurement results. Since only the combined effective values of the axis components are present, the magnitude of the magnetic flux density for each axial direction cannot be grasped.

  In addition, because it does not have an effective value analog output function for external equipment, for example, a recorder can be connected to record effective values over a long period of time, or waveform observation equipment such as an oscilloscope cannot perform effective value waveform observation. There are problems such as.

  Therefore, an object of the present invention is to display an effective value for each axis as well as a combined effective value of the X axis, the Y axis, and the Z axis, and an analog output function of an effective value for an external device. Another object of the present invention is to provide an easy-to-use magnetic field measuring apparatus.

  In order to solve the above-mentioned problem, the invention according to claim 1 has three coils arranged in common at the center among the X-axis coil, the Y-axis coil, and the Z-axis coil for detecting the magnetic field of the magnetic field to be measured, Each measurement system of each coil includes at least an integrator and an A / D converter, and an output voltage of each coil is supplied to the arithmetic control means via the integrator and the A / D converter, and the calculation is performed. A magnetic field measuring apparatus in which a predetermined parameter of the magnetic field to be measured is calculated by the control means is characterized by comprising an analog output unit that outputs an analog signal in the measurement system of each coil to an external device.

  According to a second aspect of the present invention, in the first aspect, an RMS / DC converter is connected between the integrator and the A / D converter, and an effective value converted by the RMS / DC converter is The analog output unit outputs the signal to the external device.

  A third aspect of the present invention is characterized in that, in the second aspect, the calculation control means calculates a combined effective value based on an effective value of each axis converted by the RMS / DC converter. .

  According to a fourth aspect of the present invention, in the first aspect, the filter circuit including an evaluation filter, a high-pass filter, and a low-pass filter that are alternatively selected between the integrator and the A / D converter. The output of the filter circuit is connected to the external device from the analog output unit.

  The invention according to claim 5 has three coils arranged in common at the center among the X-axis coil, the Y-axis coil, and the Z-axis coil for detecting the magnetic field of the magnetic field to be measured, and for each measurement system of the coils. Includes at least an integrator and an A / D converter, and the output voltage of each coil is supplied to the arithmetic control means via the integrator and the A / D converter, and the measured magnetic field is supplied from the arithmetic control means. In the magnetic field measuring apparatus in which the predetermined parameter is calculated, the calculation control means calculates the effective value of each axis from the digital instantaneous value input from the measurement system of each coil, and the effective value of each axis. A composite effective value is further calculated from the value, and the effective value of each axis and / or the composite effective value is displayed on a predetermined display means.

  The invention described in claim 6 is the analog output according to claim 5, wherein the effective value of each axis and / or the combined effective value calculated by the arithmetic control means is D / A converted and output to an external device. It is characterized by having a part.

The invention according to claim 7 has three coils arranged in common at the center among the X-axis coil, the Y-axis coil, and the Z-axis coil for detecting the magnetic field of the magnetic field to be measured. Includes at least an integrator and an A / D converter, and the output voltage of each coil is supplied to the arithmetic control means via the integrator and the A / D converter, and the measured magnetic field is supplied from the arithmetic control means. In the magnetic field measuring apparatus in which the predetermined parameters are calculated, the calculation control means sets the effective values of the X-axis, Y-axis, and Z-axis to x, y, z, and the combined effective value of R (= √ (x ² + y ² + z ² )), φ is obtained from tan ⁻¹ (y / x), θ is obtained from tan ⁻¹ (√ (x ² + y ² ) / z), and the resultant effective value R is expressed in polar coordinates. Displayed as system (r, θ, φ) values .

The invention according to claim 8 has three coils arranged in common at the center among the X-axis coil, the Y-axis coil, and the Z-axis coil for detecting the magnetic field of the magnetic field to be measured, and for each measurement system of the coils. Includes at least an integrator and an A / D converter, and the output voltage of each coil is supplied to the arithmetic control means via the integrator and the A / D converter, and the measured magnetic field is supplied from the arithmetic control means. In the magnetic field measuring apparatus in which the predetermined parameter is calculated, the calculation control means sets the effective values of the X-axis, Y-axis, and Z-axis to x, y, z, and sets r by √ (x ² + y ² ). It is characterized by obtaining θ by tan ⁻¹ (y / x) and displaying these values as values of the cylindrical coordinate system (r, θ, z) of rz.

  The invention according to claim 9 has three coils arranged in common at the center among the X-axis coil, the Y-axis coil, and the Z-axis coil for detecting the magnetic field of the magnetic field to be measured. Includes at least an integrator and an A / D converter, and the output voltage of each coil is supplied to the arithmetic control means via the integrator and the A / D converter, and the arithmetic control means is supplied from the operation unit. In the magnetic field measurement apparatus for calculating a predetermined parameter of the magnetic field to be measured according to an instruction, the operation unit is provided with a measurement data storage button for storing measurement data in a memory, and when the measurement data storage button is operated Only in the above, the measurement data at that time is cut out and stored in the memory.

  According to the first aspect of the present invention, by providing an analog output unit that outputs an analog signal in the measurement system of each coil to an external device, for example, a recorder or an oscilloscope is connected to transmit the measurement signal over a long period of time. You can record or observe the waveform of the measurement signal.

  According to the second aspect of the present invention, the effective value converted by the RMS / DC converter can be output from the analog output unit to the external device.

  According to the invention described in claim 3, since the calculation control means calculates the combined effective value based on the effective value of each axis converted by the RMS / DC converter, the processing load on the calculation control means can be reduced. it can.

  According to the fourth aspect of the present invention, a filter circuit including an evaluation filter, a high-pass filter, and a low-pass filter that are alternatively selected is connected between the integrator and the A / D converter. Since the output of the circuit is output from the analog output unit to the external device, the exposure level of the magnetic field to be measured, the measured value at the TCO measurement (low frequency side, high frequency side), and the like can be given to the external device.

  According to the fifth aspect of the present invention, the effective values of the X-axis, Y-axis, and Z-axis and their combined effective values are calculated by the arithmetic control means and displayed on the display means such as a monitor screen. The magnitude of the magnetic flux density of the measurement magnetic field can be grasped including the directionality.

  According to the sixth aspect of the present invention, since the effective value and / or the combined effective value of each axis calculated by the arithmetic control means is D / A converted by the analog output unit and output, the effective value is You can record and observe waveforms on the external device side.

According to the seventh aspect of the present invention, the calculation control means sets the effective values of the X-axis, Y-axis, and Z-axis to x, y, z, and the combined effective value of R (= √ (x ² + y ² + z ² )), φ is obtained from tan ⁻¹ (y / x), θ is obtained from tan ⁻¹ (√ (x ² + y ² ) / z), and the resultant effective value R is determined as the polar coordinate system (r, θ , Φ), the magnetic flux density of the magnetic field to be measured can be understood as a value having a vector.

According to the invention described in claim 8, the arithmetic control means obtains r by √ (x ² + y ² ), where x, y, z are the effective values of the X axis, the Y axis, and the Z axis, and tan ⁻¹ (y / x) is used to obtain θ, and these values are displayed as values in the rg cylindrical coordinate system (r, θ, z). Can be understood as a value having a vector.

  According to the ninth aspect of the invention, only when the measurement data storage button is operated, the measurement data at that time is cut out and stored in the memory. When the density is measured, only necessary measurement data can be stored without wasting memory capacity.

  Next, some embodiments of the present invention will be described with reference to the drawings shown in the drawings, but the present invention is not limited thereto. FIG. 1 is a block diagram schematically showing the configuration of the magnetic field measuring apparatus according to the first embodiment of the present invention, FIG. 2 is a circuit diagram showing the configuration of the filter circuit, and FIG. 3 is the configuration of the magnetic field measuring apparatus according to the second embodiment. FIG. 4 is a schematic block diagram, FIG. 4 is an external front view showing the measuring instrument main body, and FIG. 5 is an external side view showing a magnetic field sensor (magnetic field detecting unit) used by being connected to the measuring instrument main body.

In the following description, the measurement parameter of the magnetic field radiated from the measurement target such as an electric device (not shown) is the magnetic flux density. However, the magnetic flux density B [unit: stellar (T)] and the magnetic field strength H [unit: meter] As is well known, since the relationship is B = μH, measuring the magnetic flux density B is nothing more than measuring the magnetic field strength H. Note that μ is a proportionality constant (magnetic permeability), and the value of μ is 4π × 10 ⁻⁷ Henry / meter (H / m) in vacuum, air, or a nonmagnetic substance.

  As shown in FIG. 1, the magnetic field measuring apparatus includes a magnetic field detection coil 11. The coil 11 includes three coils: an X-axis coil 11x, a Y-axis coil 11y, and a Z-axis coil 11z. These three coils 11x, 11y, and 11z are arranged in a substantially spherical magnetic field sensor 10 shown in FIG. 5, preferably in a plane orthogonal to each other sharing a central point. Note that the coil 11 is simply referred to when the axis is not particularly limited.

  In the first embodiment, integrators 21x, 21y, and 21z (simply referred to as integrator 21 when no particular axis is required), filter circuits 22x, 22y, and 22z (particularly axes) for each measurement system of each axis. Are simply referred to as filter circuit 22), RMS / DC converters 23x, 23y, and 23z (in particular, simply referred to as RMS / DC converter 23 when the axis is not specified) and A / D converters 24x and 24y. , 24z (simply referred to as A / D converter 24 when the axis is not particularly specified), and the output voltage of coil 11 includes integrator 21, filter circuit 22, RMS / DC converter 23, and A / D converter. For example, the operation control means 25 is composed of a microcomputer.

Here, the output voltage V1 of the coil 11 is
V1 = k · B · N · f (k is a constant, B is a magnetic flux density, N is the number of turns, and f is a frequency)
Even when the peak magnetic flux density B is constant, it has a differential characteristic of increasing in proportion to the frequency f.

The integrator (CR integrator) 21 is used to flatten the output voltage V1 of the coil 11. That is, the output voltage V2 of the integrator 21 is
V2 = 1 / CR∫V1dt (CR is an integral constant)
Since the output decreases with frequency, the output voltage V1 of the coil 11 is flattened by the frequency effect of the integrator 21, and a voltage proportional to the magnetic flux density is obtained.

  This magnetic field measuring apparatus can perform exposure measurement by a time domain evaluation method and, for example, TCO magnetic flux density measurement which is a predetermined standard. Therefore, as shown in FIG. 2, the filter circuit 22 includes an evaluation filter 221 based on a time domain evaluation method composed of the reciprocal of the reference level of ICNIRP, and a passband used for high-frequency measurement of TCO magnetic flux density measurement of 2 kHz to 400 kHz. And a low-pass filter 223 having a passband of 5 Hz to 2 kHz used for low-frequency measurement of TCO magnetic flux density measurement is included in parallel.

  These filters 221, 222, and 223 are alternatively switched by switches SW1 to SW3, but a normal magnetic flux density measurement switch SW4 that bypasses the filter circuit 22 is further connected in parallel to the switches SW1 to SW3. Is done.

  FIG. 6 shows a graph of ICNIRP reference levels (reference levels for exposure to time-varying magnetic fields). In this graph, the solid line is the reference level for public exposure, and the dashed line is the reference level for occupational exposure.

  For reference, according to ICNIRP guidelines, populations that receive occupational exposure are usually exposed under known conditions, and that they are exposed to potential risks and take appropriate precautions. It consists of trained adults. In contrast, the public is made up of people of all ages and health conditions and may include particularly sensitive groups and individuals. In many cases, the public is not aware of exposure to electromagnetic fields. And of course, the public can't be expected to take precautions to avoid or minimize exposure. Based on these considerations, it is stated that more stringent exposure restrictions apply to the public than groups that receive occupational exposure.

  Since the evaluation filter 221 is a filter having a reciprocal number of the reference level, the description will be made by borrowing FIG. 6. In contrast to the reference level (symmetrically), the evaluation filter 221 rises to the right from 1 Hz to about 1 kHz, about 1 kHz Up to about 100 kHz, the filter characteristics are flat, and up to about 100 kHz to about 10 MHz, the filter characteristics are rising to the right. Note that the evaluation filter 221 can be combined with the integrator 21 in the previous stage in a circuit form.

  Here, assuming that the reference level value of ICNIRP is B and the value passed through the evaluation filter 221 is A, the output voltage (voltage proportional to the magnetic flux density) V2 of the integrator 21 is the reference value of ICNIRP by the evaluation filter 221. By multiplying the reciprocal of the level, A = V2 / B (dimensionless number), and when the frequency is single and V2 = B, the exposure level is 100%.

  The RMS / DC converter (Root Mean Squared to Direct Current converter) 23 squares the voltage that has passed through the filter circuit 22 (including the voltage that bypasses the filter circuit 22 by the switch SW4), takes its average value, and An effective value converted voltage equal to the value obtained by taking the square root is output.

That is, assuming that instantaneous values at time t obtained from the X-axis coil 11x, Y-axis coil 11y, and Z-axis coil 11z are x (t), y (t), and z (t), respectively, the effective magnetic flux density on the X-axis is effective. The value x (t) _RMS , the effective value y (t) _RMS of the magnetic flux density on the Y axis, and the effective value z (t) _RMS of the magnetic flux density on the Z axis are expressed by the following equations (1) to (3) ( Usually, T is 1 second).

The A / D converter 24 converts the effective values x (t) _RMS , y (t) _RMS , z (t) _RMS output from the RMS / DC converter 23 into digital data and _{supplies the} digital data to the arithmetic control means 25. The arithmetic control means 25 calculates a combined effective value R (t) _RMS by the following equation (4) based on the effective values x (t) _RMS , y (t) _RMS , z (t) _RMS , The effective value (measured value) is displayed on the display unit 30 including, for example, a liquid crystal display panel.

Note that which effective value is displayed can be appropriately selected by the display selection circuit 251. That is, the combined effective value R (t) _RMS and the effective values x (t) _RMS , y (t) _RMS , z (t) _{RMS of} each axis can be displayed together, or only the effective value of each axis can be displayed. It is also possible to select and display. In the exposure measurement, when the exposure level is 100% or more, a warning can be issued by a notifying means such as a buzzer or LED (not shown).

  This magnetic field measurement apparatus includes an analog output unit 40 that outputs an analog signal in each measurement system of the coils 11x, 11y, and 11z to an external device (not shown) such as a recorder or an oscilloscope. The measurement system of the X-axis coil 11x will be described. Any one of the output of the integrator 21x, the output of the filter circuit 22x, and the output of the RMS / DC converter 23x is selected by the switching circuit 41x and given to the analog output unit 40. It is done. Similarly, in the other measurement systems, any one of the outputs of the integrator 21, the filter circuit 22, and the RMS / DC converter 23 is selected by the switching circuits 41 y and 41 z and supplied to the analog output unit 40. .

  Next, the magnetic field measuring apparatus according to the second embodiment shown in FIG. 3 will be described. The magnetic field measurement apparatus according to the second embodiment is different from the first embodiment in that the RMS / DC converters 23x, 23y, and 23z are not provided in the measurement system of the coils 11x, 11y, and 11z.

Therefore, in the magnetic field measuring apparatus according to the second embodiment, the calculation control means 25 calculates the effective values x (t) _RMS , y (t) of the axes X, Y, and Z according to the above equations (1) to (3). _RMS , z (t) After calculating _RMS , the combined effective value R (t) _RMS is calculated by the above equation (4). The display is the same as in the first embodiment.

The magnetic field measurement apparatus according to the second embodiment also includes an analog output unit 40. In this case, the analog output is an effective value and / or a combined effective value of each axis. That is, the arithmetic control circuit 25 calculates the effective values x (t) _RMS , y (t) _RMS , z (t) _RMS and the combined effective value R (t) _RMS of each axis X, Y, Z by digital calculation. A data selection circuit 252 for selecting data is provided, and the effective value data selected by the data selection circuit 252 is converted to analog by the D / A converter 42 and supplied to the analog output unit 40.

  In addition, as described in the first embodiment, for example, the output of the integrator 21 and the output of the filter circuit 22 are directly extracted from the measurement system of each coil 11 and added to the analog output unit 40, for example. May be.

  The measuring system including the integrator 21, the filter circuit 22, the RMS / DC converter 23, and the A / D converter 24, the arithmetic control means 25, the display unit 30, and the analog output unit 40 of each coil 11 are shown in FIG. It is provided in the main body 20. Note that the analog output unit 40 is not shown because it is provided on, for example, the bottom side of the measuring instrument body 20. The measuring device main body 20 has a female connector 20a that is a counterpart of the male connector 10a of the magnetic field sensor 10, and the magnetic field sensor 10 is connected to the measuring device main body 20 during magnetic field measurement.

  A display unit 30 and an operation unit 50 are assigned to the front face of the measuring instrument main body 20. In this example, the operation unit 50 includes a power button 51, a magnetic field measurement mode switching button 52, a display axis switching button 53, a range switching button 54 including an auto range, a maximum value hold button 55, a measurement data storage button 56, and a storage. A memory view button 57 that displays measurement data and an output button 58 that is operated when outputting measurement data to an external device such as a personal computer are provided.

  In addition to the normal magnetic field measurement mode (10 Hz to 400 kHz), this magnetic field measuring apparatus has a magnetic flux density measurement mode defined by the TCO (low frequency measurement of 5 Hz to 2 kHz band, high frequency range of 2 kHz to 400 kHz band). Measurement) and exposure amount measurement mode (occupational exposure, public exposure) by time domain evaluation method, and by pressing the magnetic field measurement mode switching button 52, these measurement modes are cyclically switched. The switching state of the measurement mode will be described with reference to FIG.

  First, as a default, the switch SW4 in the filter circuit 22 is turned on, and a normal magnetic field measurement mode (10 Hz to 400 kHz) is selected as shown in FIG. In this state, when the magnetic field measurement mode switching button 52 is pressed once, the switch SW3 is turned on and, as shown in FIG. 7B, the low frequency measurement in the 5 Hz to 2 kHz band in the TCO magnetic flux density measurement mode is selected. Is done. Subsequently, when the magnetic field measurement mode switching button 52 is pressed once, the switch SW2 is turned on, and as shown in FIG. 7C, the high frequency measurement in the 2 kHz to 400 kHz band in the TCO magnetic flux density measurement mode is selected. The

  Subsequently, when the magnetic field measurement mode switching button 52 is pressed once, the switch SW1 is turned on, and the exposure (general) mode (public exposure) in the exposure measurement mode is selected as shown in FIG. 7 (d). Is done. Subsequently, when the magnetic field measurement mode switching button 52 is pressed once, an exposure (occupation) mode (occupational exposure) in the exposure amount measurement mode is selected as shown in FIG. By pressing the measurement mode switching button 52 once, the normal magnetic field measurement mode shown in FIG.

The TCO magnetic flux density measurement mode is a mode for measuring the magnetic flux density radiated from a monitor screen such as a personal computer. As described above,
(Low frequency): 5 Hz to 2 kHz; front 30/50 cm, ≦ 200 nT
(High region): 2 kHz to 400 kHz; 30 cm in front and 50 cm in circumference, ≦ 25 nT
It is prescribed.

  In the exposure measurement mode, the calculation control means 25 applies the ICNIRP reference level for occupational exposure indicated by a chain line in the graph of FIG. The reference level of ICNIRP for public exposure indicated by the solid line in the graph is applied.

  When the exposure level is a predetermined threshold (for example, 100%) or more, or when 200 nT (nantesla) or more is measured in the low-frequency measurement in the TCO magnetic flux density measurement mode and 25 nT or more is measured in the high-frequency measurement, an unillustrated notification It is preferred to operate the means and inform the user.

Each time the display axis switch button 53 is pressed once, the display selection circuit 251 is sequentially switched, and XYZ (the combined effective value R (t) _RMS ) of each coil 11 → X (the magnetic flux density detected by the coil 11x). Instantaneous value x (t) or effective value x (t) _RMS ) → Y (the instantaneous value y (t) or effective value y (t) _{RMS of} the magnetic flux density detected by the coil 11y) → Z (into the coil 11z) The instantaneous value z (t) or effective value z (t) _RMS ) of the detected magnetic flux density and the display axis can be sequentially switched, so that the instantaneous value, effective value, and combined effective value of each display axis can be known. it can. This is also one of the features of the present invention.

  Further, when the measurement data storage button 56 is pressed during the magnetic field measurement, the measurement data at that time is cut out and stored in a memory (not shown). For example, the magnetic flux density is measured at multiple points while moving the place. In this case, only necessary measurement data can be stored without wasting memory capacity, and this point is also included in the features of the present invention. Apart from this, for example, by providing a continuous storage function similar to the continuous shooting function of a digital camera, it is also possible to store fluctuations in measured values within a limited time.

  Next, with reference to FIGS. 8 to 11, two examples of embodiments for displaying measured values will be described. 8 and 10, the filter circuit 22 is omitted from the measurement system of each coil 11. In this case, the presence or absence of the filter circuit 22 is not particularly problematic.

First, in the magnetic field measuring apparatus of FIG. 8 (third embodiment of the present invention), the arithmetic control means 25 is configured to calculate the effective values x (t) _RMS , y (t) _RMS , z (t) of the axes X, Y, Z. ) From the _RMS value, the combined effective value R (t) _RMS is displayed in the polar coordinate system (r, θ, φ). In this example, the RMS value of each axis is obtained by the RMS / DC converter 23 included in the measurement system of each coil 11, and the effective value of each axis is obtained in the second embodiment of FIG. As described above, it may be a value calculated by the arithmetic control means 25.

For convenience of explanation, each of the effective values of the X, Y, and Z axes is x, y, z, and the combined effective value is R (= √ (x ² + y ² + z ² )). ^-1 (y / x) and φ is obtained by tan ⁻¹ (√ (x ² + y ² ) / z), and the resultant effective value R is determined as the value of the polar coordinate system (r, θ, φ). indicate.

  An example of the display is shown in FIG. 9, but it can also be a three-dimensional vector display. Note that when x = 0, y / x cannot be obtained and φ cannot be obtained. In this case, φ may be treated as π / 2 by applying a function such as atan2 (arc tangent 2). . Similarly, when z = 0, θ is treated as π / 2. Also, by using atan2, the correct angle φ can be obtained regardless of the polarities of x and y.

Next, in the magnetic field measurement apparatus of FIG. 10 (the fourth embodiment of the present invention), the calculation control means 25 is the effective value x (t) _RMS , y (t) _RMS , z (of each axis X, Y, Z). t) From the _RMS value, the combined effective value R (t) _RMS is displayed in the rg cylindrical coordinate system (r, θ, z). Here, the effective value of each axis is obtained by the RMS / DC converter 23 included in the measurement system of each coil 11. The effective value of each axis is described in the second embodiment of FIG. Thus, the value calculated by the arithmetic control means 25 may be used.

For convenience of explanation, assuming that the effective values of the X-axis, Y-axis, and Z-axis are x, y, and z, the arithmetic control means 25 obtains r by √ (x ² + y ² ) and tan ⁻¹ (y / x ) To obtain θ and display these values as values in the rz cylindrical coordinate system (r, θ, z).

  An example of the display is shown in FIG. 11, but it can also be a three-dimensional vector display. Note that when x = 0, y / x cannot be obtained and θ cannot be obtained. In this case, θ may be treated as π / 2 by applying a function such as atan2 as in the above example. . Also, by using atan2, the correct angle θ can be obtained regardless of the polarities of x and y.

  As described above, according to the present invention, the effective value for each axis as well as the combined effective value of the X-axis, Y-axis, and Z-axis can be displayed in various modes, and the effective value for the external device can be displayed. An easy-to-use magnetic field measuring device having an analog value output function and the like is provided.

1 is a block diagram schematically showing the configuration of a first embodiment of the present invention. The circuit diagram which shows the structure of a filter circuit. The block diagram which shows schematically the structure of 2nd Embodiment of this invention. The external appearance front view which shows a measuring device main body. The external appearance side view which shows the magnetic field sensor connected and used for the said measuring device main body. The graph which shows the reference level of ICNIRP. Explanatory drawing which shows the switching state of magnetic field measurement mode. The block diagram which shows roughly the structure of 3rd Embodiment of this invention. The display screen figure which shows the example of a display of the said 3rd Embodiment. The block diagram which shows roughly the structure of 4th Embodiment of this invention. The display screen figure which shows the example of a display of the said 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Magnetic field sensor 11 (11x, 11y, 11z) Coil 20 Measuring device main body 21 (21x, 21y, 21z) Integrator 22 (22x, 22y, 22z) Filter circuit 221 Evaluation filter 222 High pass filter 223 Low pass filter 23 (23x, 23y , 23z) RMS / DC converter 24 (24x, 24y, 24z) A / D converter 25 arithmetic control means 30 display unit 40 analog output unit 50 operation unit

Claims (9)

The X-axis coil, the Y-axis coil, and the Z-axis coil that detect the magnetic field of the magnetic field to be measured have three coils arranged at the center, and at least an integrator and A / D conversion for each measurement system of each coil A magnetic field in which the output voltage of each coil is supplied to the arithmetic control means via the integrator and the A / D converter, and a predetermined parameter of the measured magnetic field is calculated by the arithmetic control means. In the measuring device,
A magnetic field measuring apparatus comprising an analog output unit for outputting an analog signal in the measurement system of each coil to an external device.   An RMS / DC converter is connected between the integrator and the A / D converter, and an effective value converted by the RMS / DC converter is output from the analog output unit to the external device. The magnetic field measurement apparatus according to claim 1.   The magnetic field measuring apparatus according to claim 2, wherein the arithmetic control unit calculates a combined effective value based on an effective value of each axis converted by the RMS / DC converter.   A filter circuit including an evaluation filter, a high-pass filter, and a low-pass filter that are alternatively selected is connected between the integrator and the A / D converter, and an output of the filter circuit is output from the analog output unit to the analog output unit. The magnetic field measuring apparatus according to claim 1, wherein the magnetic field measuring apparatus is output to an external device. The X-axis coil, the Y-axis coil, and the Z-axis coil that detect the magnetic field of the magnetic field to be measured have three coils arranged at the center, and at least an integrator and A / D conversion for each measurement system of each coil A magnetic field in which the output voltage of each coil is supplied to the arithmetic control means via the integrator and the A / D converter, and a predetermined parameter of the measured magnetic field is calculated by the arithmetic control means. In the measuring device,
The calculation control means calculates the effective value of each axis from the digital instantaneous value input from the measurement system of each coil, and further calculates the combined effective value from the effective value of each axis, And / or the combined effective value is displayed on a predetermined display means.   6. An analog output unit that D / A converts the effective value of each axis and / or the combined effective value calculated by the arithmetic control unit and outputs the resultant value to an external device. Magnetic field measuring device. The X-axis coil, the Y-axis coil, and the Z-axis coil that detect the magnetic field of the magnetic field to be measured have three coils arranged at the center, and at least an integrator and A / D conversion for each measurement system of each coil A magnetic field in which the output voltage of each coil is supplied to the arithmetic control means via the integrator and the A / D converter, and a predetermined parameter of the measured magnetic field is calculated by the arithmetic control means. In the measuring device,
The arithmetic control means sets tan ⁻¹ (X, Y, Z) as tan ⁻¹ (x, y, z) and R (= √ (x ² + y ² + z ² )) as the combined effective value. y is obtained from y / x), θ is obtained from tan ⁻¹ (√ (x ² + y ² ) / z), and the resultant effective value R is displayed as a value in the polar coordinate system (r, θ, φ). Magnetic field measuring apparatus characterized by the above. The X-axis coil, the Y-axis coil, and the Z-axis coil that detect the magnetic field of the magnetic field to be measured have three coils arranged at the center, and at least an integrator and A / D conversion for each measurement system of each coil A magnetic field in which the output voltage of each coil is supplied to the arithmetic control means via the integrator and the A / D converter, and a predetermined parameter of the measured magnetic field is calculated by the arithmetic control means. In the measuring device,
The arithmetic control means obtains r by √ (x ² + y ² ), where x, y, z are the effective values of the X axis, Y axis, and Z axis, and θ by tan ⁻¹ (y / x). And displaying these values as values in the rz cylindrical coordinate system (r, θ, z). The X-axis coil, the Y-axis coil, and the Z-axis coil that detect the magnetic field of the magnetic field to be measured have three coils arranged at the center, and at least an integrator and A / D conversion for each measurement system of each coil And the output voltage of each coil is supplied to the arithmetic control means via the integrator and the A / D converter, and the arithmetic control means determines the predetermined magnetic field to be measured in accordance with an instruction from the operation unit. In the magnetic field measuring apparatus for calculating the parameters of
The operation unit is provided with a measurement data storage button for storing measurement data in a memory, and the measurement data at that time is stored in the memory so as to be cut only when the measurement data storage button is operated. A magnetic field measuring apparatus.

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