JPH04109184A - Three-dimensional integrated flux meter - Google Patents

Abstract

PURPOSE:To expand the measurement region and improve measurement precision by judging whether the measured value of either one axis is a preset value or above or below among the measured values detected three-dimensionally, and changing the amplification factor. CONSTITUTION:Detection signals of X-Z axis detecting means 1, 3, 5 are amplified by X-Z axis amplifying means 2, 4, 6 via control signals 22-24 at the amplification factor determined by an amplification factor switching means 12, they are selected by a multiplexer 8 according to the control signal 21, they are applied with A/D conversion 9 and inputted to an arithmetic means 10 to determine the magnetic field strength in three axes, and it is temporarily stored in a measured value storing means 11. An amplification factor judging means 12 judges whether the magnetic field strength is larger than the first set value or smaller than the second set value, the result is sent to an amplification factor switching means 13, and the present amplification factor is changed to the optimum amplification factor or maintained as it is. An accumulated value storing means 14 accumulates the magnetic field strength in three axes and the time of the measurement period, and the contents are added and stored.

Description

[Detailed Description of the Invention] [Field of Industrial Application] Research is progressing on the effects of radio waves and magnetic fields, which are categorized under the category of non-ionizing radiation, on living things. This invention relates to a three-dimensional integral magnetometer that measures magnetic field strength regardless of the relationship between the magnetic field strength and the integral value of the magnetic field strength.

[Prior Art] Generally, a magnetic flux needle called a Franks gate (saturated iron core type) has been used to measure the magnetic flux emitted from a ferromagnetic material. However, it only measured instantaneous magnetic flux in the measurement environment.

[Background] Magnetic fields are all around us due to the earth's magnetism or various electrical devices that use permanent magnets or electromagnets.

However, in these cases, the magnetic field strength is usually extremely small or the magnetic field is localized in a certain area, and the effect on the environment and the human body is small.

However, recently, due to the development of science and technology, opportunities for the human body to be directly exposed to strong magnetic fields have increased. The source of these magnetic fields is a strong magnet such as a rare earth magnet or a superconducting magnet. A vehicle transportation system that uses this magnetic force, an analytical device such as an angular magnetic resonance absorption measuring device, and an NMR-CT that uses nuclear magnetic resonance absorption to observe the state of cells in the human head in slices. There are large-scale nuclear fusion experimental devices such as , Ll (D), etc., and the magnetic field used ranges from 1 to 5 T (Tesla), and the leakage magnetic field in the vicinity is too large to be ignored.

The effects of magnetism on the environment or the human body have not yet been investigated in detail, but there are reports that extremely strong magnetic fields may have a negative effect on the environment or the human body, and that exposure to moderate magnetic fields is good for health. For example, as advised by the British Radiological Protection Board, do not exceed a static magnetic field of 1.57.

Time-varying magnetic field: 20 if the changing time is 10ms or more
Do not exceed SIT/S-rms SO, change time 1
If it is less than 0 ms (dB/dt) 52250 t<4° High frequency: Absorption rate in the whole body is 0.4511 kg 52-ISO or less.

Workers' radiation exposure: Long term - 0.02T for the whole body, 0.2T for the hands and arms.
.

Within 15 minutes - whole body 0.2T, hands 112T.

In addition, as a guideline of the US Food and Drug Administration (FDA), static magnetic fields: Exposure to all or part of the body should not exceed 2T.

Time-varying magnetic field: 3T/3T for exposure of all or part of the body
Do not exceed 3.

High-frequency electromagnetic field: Specific absorption rate is 0.4 W/kg on average,
Do not exceed 2W/kg locally.

Exposure of workers (U.S. Department of Energy interim test): 8-hour workday - 0.01T for the whole body, 0.01T for the hands. IT1 hour or less exposure: whole body 0. IT, hand IT exposure for 10 minutes or less: whole body 0.5
T, hand 2T.

Under such circumstances, it must be said that it is wise to avoid exposing the human body to strong magnetic fields as much as possible, and to avoid being exposed to magnetic fields for long periods of time even if the field is relatively weak. There are many opportunities for people to be exposed to magnetic fields of various strengths under various conditions, and it is important to know how much magnetic field they have been exposed to in total, especially for those who work in a magnetic field environment. It's necessary. However, a simple device that integrates the time of exposure to magnetism according to the strength of the magnetic field has not yet been developed.

Therefore, an object of the present invention is to provide a simple integrating magnetometer.

[The problem that the invention tries to solve! ! ] According to the present invention, a three-dimensional integrating magnetometer that satisfies the above requirements is configured by combining the magnetic detection means and the time counting means, and the measured value can be set even on any one axis of the magnetic detection means. By providing a means for determining whether the value is above or below, the measurement area is expanded.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a portable magnetometer that counts the integral value of the amount of magnetic flux exposed using three-dimensionally arranged detection means. The detection means arranged in the magnetic detection means and the amplification means for amplifying the respective detection outputs are configured so that the amplification factor can be changed in at least two steps or more, so that the measured value on any one axis of the magnetic detection means is greater than or equal to the set measurement value. Amplification factor determining means and amplification factor switching means are provided to determine whether the measurement area has become larger, thereby making it possible to expand the measurement range.

[Function] In the portable magnetometer configured as described above that counts the integral value of the amount of exposed magnetic flux, the measured value can be set in any one axis of the three-dimensionally arranged detection means for each measurement. By determining whether the value is above or below the value and switching the amplification factor, it is possible to expand the measurement area and improve measurement accuracy.

[Example] Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. Y
The detection signal of the X-axis detection means 1 arranged on the axis is amplified by the X-axis amplification means 2. Similarly, Y located on the Y axis
The detection signal of the axis detection means 3 is amplified by the Y-axis amplification means 4, and the detection signal of the two-wheel detection means 5 arranged on the z-axis is
It is amplified by the Z-axis amplification means 6. Each of the detection means 1.
3.5 and each amplification means 2.4, 6 are operated by an operation control means 7.
control signals 22, 23, and 24. Further, each amplification means 2.4.6 has an amplification factor switching means 13.
The amplification factor is determined by the control signal 26 outputted by. The output signal of each of the amplifying means 2.4.6 is selected by a multiplexer 8 depending on the control signal 21 of the operation control means 7. Then, in accordance with the control signal 25 of the operation control means 7, this signal is converted from the output signal of each of the amplification means 2.4.6, which is an analog value, to a digital value by the A/D conversion means 9. The calculation means 10 calculates the above A/
The output of the D conversion means 9 is calculated into magnetic field strength and temporarily stored in the measured value storage means 11. The amplification factor determining means 12 determines whether the magnetic field strength is larger than the first setting value or smaller than the second setting value, and sends the result to the amplification factor switching means 13 to change the amplification factor. Change or maintain.

2nd W! A control signal 2 outputted from the operation control means 7 to J
1.22.23.24.25, and amplification factor switching means 1
3 shows a time chart of the control signal 26 outputted by No. 3. The control signal outputted by the operation control means 7 is the output of a timing generation means 17 which divides the output signal of the oscillation circuit 15 by a frequency dividing circuit 16 and generates the timing of the measurement cycle from the output signal of the frequency dividing circuit 16. Signal and the frequency divider circuit 16
is generated from the output signal of

As mentioned above, the calculation means 10 is connected to the A/D conversion means 9.
The detected electric signal is converted into a magnetic field strength and temporarily stored in the measured value storage means 11, and the amplification factor determination means 12 determines the optimum amplification factor.

Furthermore, the actual magnetic field strength is calculated from the magnetic field strength components of the x, y, and z axes.

FIG. 3 shows a diagram in which the magnetic field strength is broken down into three axes (X, Y, and z axes).

From Fig. 4, the magnetic field strength (magnetic flux density) B is B--r (B
x” ”+By” +Bz” ) (Equation 1), and the calculation means 10 receives 3
Recall the magnetic field strength of the axis, perform this calculation, further calculate the product of the calculated magnetic field strength B and the measurement period time,
It is added to the contents of the integrated value storage means 14 and stored again. FIG. 4 shows an example of the integration method, in which the integrated value storage means 14
Bh, which is the amount of magnetic flux, is stored in , and the amount of magnetic flux Bh is Bh - Σ (magnetic flux strength B * waiting time) (Formula 2) The contents of the integrated value storage means 14 and the output signal of the frequency dividing circuit 16 The contents of the time counting means 18, which counts the total measurement time from the start of the measurement, are displayed on the display device 20 via the display control means 19.

The basic configuration of one circuit embodiment of the present invention of the detection means and the amplification means is shown in the fifth rfIJ. The detection means 1 is composed of a magnetic detection element such as a Hall element 27, a current control resistor R1, and a transistor Tri connected in series. be done. The two output terminals of the magnetic detection element 27 are resistors R2 and R for amplification.
3 to the amplifier 28. + of the amplifier 28
The side input terminal is grounded via a resistor R4, and the output of the amplifier 28 is negatively fed back to the negative input terminal via a resistor R5. This circuit configuration provides a differential amplifier circuit that takes and amplifies the difference between two input voltages. The output voltage VQUT is
R2-R3, R4=R50) when VOUT-R5(VINI-VIN2)/R3
It is expressed by (Equation 3), and R5/R3 becomes the amplification factor. Transistor Tr2 is connected between the power supply terminal of amplifier 28 and ground. The gate terminals of the transistors Trl and Tr2 are controlled by the control signal 19 output from the operation control means, and the Mfm signal 22 outputs "H" and is turned ON during measurement.
In state am, the X-axis detection means 1 and the X-axis amplification means 2 are brought into operation. Further, by setting the output of the control signal 22 to "L", the device is brought into a non-operating state and the operating current is canted. Y-axis detection means 3, Y-axis amplification stage 4, Z-axis detection means 5, Z
The axial amplification means 6 also has a similar configuration.

FIG. 6 shows an embodiment of a circuit for switching the amplification factor of the detection means and the amplification means according to the present invention. The difference from the basic configuration shown in FIG. 5 is that a resistor R6 is provided in series with the resistor R4, a switch SWI is provided in parallel with the resistor R6, and a resistor R5 is provided.
A resistor R7 is provided in series with the resistor R7, and a switch SW2 is provided in parallel with the resistor R7.

The switches SWI and Sn2 are controlled by a control signal 26 output by the amplification factor switching means 13 to open and close the switches. From equation 3, the amplification factor is expressed as 125/R3 when the switch is closed. If R6=R7 when the switch is open, it is expressed as (1?5+R7)/R3, and the amplification factor is changed by opening and closing the switch.

Next, a block diagram of an embodiment of the present invention controlled by a microcomputer shown in FIG. 7 will be explained.

As shown in FIG. 7, a logic operation means 31, a program memory (ROM) 32, a data memory (RAM)
) 33 etc. constitute a micro combinator. The logical operation processing circuit 31 is composed of an ALU, an operation register, an address control register, an intra-frame decoder, etc., and is connected to peripheral circuits through a data bus 36 and an address bus 37.

The ROM 32 is a program memory that stores software in which processing procedures are replaced with instructions.

The RAM 33 is a data memory and is used to temporarily store various information.

The system clock generation circuit 28 receives the output of the oscillation circuit 15 and generates a system clock necessary for the operation of the logic operation processing circuit 31.

The interrupt vlIm circuit 30 receives the output of the frequency divider circuit 16 that divides the output of the oscillation circuit 15, and generates an activation signal for starting the operation of the logic operation processing circuit 31, and the contents of the interrupt are as follows. Read via data bus 3G.

It is generated from the output signal of the timing generating means 17 which generates the timing of the measurement period from the output signal of the frequency dividing circuit 16 and the output signal of the frequency dividing circuit 16, and is generated from the output signal of the frequency dividing circuit 16.
In this step, control signals for the detection means 34 and the amplification means 35 are generated from the output signal of the frequency dividing circuit 16. The detection means 34 includes each X, Y, and Z axis detection means 1.3 in FIG.
．． 5 collectively, and similarly the amplifying means 3
5 represents each x, y, and z axis amplification means 2.4 in FIG.
This is a general term for all 6.

The amplification factor of the amplification means 35 is switched according to information from the amplification factor switching means 13, and the output is selected by the multiplexer 8, converted into a digital signal by the A/D conversion means 9, and sent to the logic signal via the data bus 36. The data is read into the arithmetic processing circuit 31. The amplification factor switching means 13 transfers the amplification factor determined by the logical operation processing circuit 31 to the data bus 36.
written via.

Further, the display control means 19 supplies information supplied via the data bus 36 to the display device 20 for display.

The operating procedure when controlled by the microcomputer shown in FIG. 7 will be explained with reference to the flowchart shown in FIG. 8 showing the operating procedure of the present invention.

From the interrupt control circuit 30 to the logic operation processing circuit 31,
When an interrupt occurs, X-axis drive is selected for the operation control means 7 in process 61, and the control signal 22 in FIG. 1 is output to drive the X-axis detection means 1 and the X-axis amplification means 2. A multiplexer 8 selects the output signal of the X-axis amplifying means 2. In process 62, WAIT is performed for a certain period of time until the operation of the amplification means becomes stable, and in process 63, the A/D
The converting means 9 is operated, the converted data is read into the logic operation means via the data bus 36, and the magnetic field strength BX is calculated in the process 64. In the process 65, the amplification factor is "1" (when the magnetic field strength is the level of the amplification factor control signal 26), and No (hereinafter abbreviated as N).
If YES (hereinafter abbreviated as Y), the process branches to process 68. In process 66, it is determined whether the magnetic field strength BX calculated in process 64 is larger than the first set value B1, and if Y (large), the amplification factor is set to "1" in process 67, and the process returns to the beginning of process 61. .

When N (small), the process branches to process 70. In process 68, the magnetic field strength BX calculated in process 64 is set to a second set value B.
It is determined whether it is smaller than 1, and if Y (small), the amplification factor is set to "0" in process 69 and the process returns to the beginning of process 61. When N (large), the process branches to process 70. In process 70, the measured value is stored in the measured value storage means 11.

Next, in process 71, when Y-axis drive is selected for the operation control means 7, the control signal 23 in FIG. 1 is output, and the X-axis detection means 3 and the Y-axis amplification means 4 are driven. A multiplexer 8 selects the output signal of the Y-axis amplification means 4. In process 72, a WAIT period is performed for a certain period of time until the operation of the amplification means becomes stable, and in process 73, the A/D conversion means 9
The converted data is read into the logic operation means via the data bus 36, and the magnetic field strength BY is calculated in process 74. Note that ■, ■, and ■ in FIG.
, ■ means branch connections when the flowchart spans two or more pages.

In process 75, it is determined whether the amplification factor is "1", and N
When YES, the process branches to process 76, and when Y, the process branches to process 77. In process 76, it is determined whether the magnetic field strength BY calculated in process 74 is larger than the first set value B1, and if Y (large), the process branches to process 67, and if N (small), the process branches to process 78.

In process 77, the magnetic field strength BY calculated in process 74 is
is smaller than the second set value B1, and if Y (small), the process branches to process 69, and if N (large), the process branches to process 78. In process 78, -1 is stored in the measured value storage means 11.

Next, in process 79, when Z-axis drive is selected for the operation control means 7, the control signal 24 shown in FIG. 1 is output, and the Z-axis detection means 5 and the Z-axis amplification means 6 are driven. A multiplexer 8 selects the output signal of the Z-axis amplifying means 6. In process 80, a WAIT period is performed for a certain period of time until the operation of the amplification means stabilizes, and in process 81, the A/D conversion means 9
is operated, the converted data is read into the logic operation means via the data bus 36, and the magnetic field strength BZ is calculated in process 82. In process 83, the amplification factor is
”, and if N, the process branches to process 84, and if Y, the process branches to process 85. In process 84, it is determined whether the magnetic field strength BZ calculated in process 82 is larger than the first set value B1, and Y (large), the process branches to process 67, and when N (small), the process branches to process 86. In process 77, it is determined whether the magnetic field strength BY calculated in process 74 is smaller than the second set value Bl, and Y (small), the process branches to process 69, and when N (large), the process branches to process 86. In process 86, -1 is stored in the measured value storage means 11.

In process 87, the magnetic field intensities BX, BY, and BZ in the X, Y, and Z axis directions are read out from the calculated value storage means 11, and r (B x 322 So +B )l S22
S.

+B z 522 So) is calculated.In process 88, the product of the magnetic field strength B calculated in process 87 and the time of the measurement period is calculated.In process 89, the result calculated in process 88 is stored in the integrated memory. It is added to means 14 and stored again. In process 90, the time of the measurement cycle is added to the time counting means 18 and stored again. In process 91, the display process on the display device 19 is performed, and in
Return to ALT state.

[Effects of the Invention] As explained above, the present invention provides a portable magnetometer that counts the integral value of the amount of magnetic flux exposed to radiation, in which detecting means arranged three-dimensionally and amplifying means for amplifying the respective detection outputs are used. has a configuration in which the amplification factor can be varied in at least two stages,
Provided with an amplification factor determining means and an amplification factor switching means for determining whether the measured value of any one axis of the magnetic detection means is equal to or higher than a set first measured value or lower than a set second measured value,
It has been made possible to expand the total i* area.

Furthermore, in this embodiment, switching of the amplification factor has been explained in two stages, but if the switching is made in more stages, it becomes possible to expand the measurement area and improve measurement accuracy.

In Figure 8, the comparison with the set value was performed one axis at a time after measuring each axis, but the same effect can be obtained even if the three axes are measured and then compared all at once, and the amplification factor can be set for each axis. By doing so, it is possible to further improve measurement accuracy.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a time chart of control signals output from the operation control means 7, and Fig. 3 is a breakdown of magnetic field strength into three axes (X, Y, Z axes). diagram,
Fig. 4 is a diagram showing an example of the integration method, Fig. 5 is a detection means,
The basic configuration of one circuit embodiment of the amplification means according to the present invention, FIG. 6 shows an embodiment of a circuit capable of switching the amplification factor of the detection means and amplification means according to the present invention, and FIG. 7 shows a circuit embodiment of the present invention controlled by a microcomputer. FIG. 8 is a block diagram showing an embodiment and a flowchart showing the operating procedure of the present invention. 1...X-axis detection means 3...Y-axis detection means 5...Z-axis detection means 7...Operation control means 9...A/D conversion means 10...Calculation means 11... Calculated value storage means 2
. . . X-axis amplification means 4 . . Y-axis amplification means 6 . X value storage means 15... oscillation circuit I6... frequency dividing circuit 17...
- Timing generation means 18...Time counting means 19...Display control means 20...Display devices 21, 2
2.23.24.25.26...Control signal 27...
Detection element 28...Amplifier 29...System clock generation circuit 30...Interrupt control circuit 31...Logic operation processing circuit 32...ROM 33...RAM34...
・Detection means 35... Amplification means 36... Data bus 37... Address bus magnetic field strength on three axes (X,
Figures 3 and above, decomposed into Y and Z axes) Applicant Seiko Electronics Co., Ltd. Representative Patent Attorney Keisuke Hayashi Figures 4 and 5 Figures 6 and 9

Claims (4)

[Claims] (1) In a three-dimensional integrating magnetometer that measures the integral value of magnetic field strength, (a) three magnetic detection means arranged three-dimensionally in the X-axis, Y-axis, and Z-axis directions; (b) the above three three amplifying means capable of changing the amplification factor for amplifying the detection signal of each of the magnetic detecting means; (c) operation control means for controlling the operation of the magnetic detecting means and the amplifying means; (d) the a multiplexer that selects the output signals of the three amplification means according to a control signal of the operation control means; (e) an A/D conversion means that converts the analog signal output from the multiplexer into a digital signal; (f) (g) a calculation means for calculating magnetic field strength from the digital signals in the three axis directions; (h) a result of the calculation means, a first setting value, and a second setting value; (i) amplification factor switching means that switches the amplification factor according to the result of the amplification factor discrimination means; (j) vector calculation of the magnetic field strength of the three axes, and A three-dimensional integrated magnetic flux meter comprising: integrated value storage means for storing the sum of products with vector-calculated magnetic flux strengths; and (k) a display device for displaying the contents of the integrated value storage means. (2) The three-dimensional integrating magnetometer according to claim 1, wherein the magnetic detection means is a Hall element. (3) Claim 1, wherein the magnetic detection means is a magnetoresistive element.
The three-dimensional integrated flux meter described. (4) The three-dimensional integrated flux meter according to claim 1, wherein the operation control means cuts off current between the three detection means and their corresponding amplification means when not measuring.