JPH0493781A - Three-dimensional integrating fluxmeter - Google Patents

Abstract

PURPOSE:To reduce consumption of current and to lessen an error in computation by a method wherein detecting means disposed three-dimensionally are driven in a time-sharing manner for each measuring period. CONSTITUTION:An operation control means 7 controls an X-axis detecting means 1, a Y-axis detecting means 1 and a Z-axis detecting means 3 and an X-axis amplifying means 2, a Y-axis amplifying means 4 and a Z-axis amplifying means 6 on the basis of a signal of a timing generation means 12. Next, a multiplexer 8 selects output signals of the amplifying means 2, 4 and 6 according to a control signal 18 of the control means 7 and an A/D conversion means 9 converts them into digital values. An arithmetic means 13 converts the digital signals into magnetic field strengths and computes an actual magnetic field strength from the components of the magnetic field strengths on the axes X,Y and Z. Moreover, the computed magnetic filed strength, a computed magnetic field strength from data measured after the time of some measuring period, and an integrated value encompassed with the time of the measuring period, are subjected to computation, and the result of the computation is added to the content of an integrated value storage means 14 and stored. The content of this storage means 14 and the content of a time counting means 15 counting the entire measuring time from the start of measurement are displayed in a display device 17 through the intermediary of a display control means 16.

Description

[Detailed Description of the Invention] [Industrial Application Field] Research is underway on the effects of radio waves and magnetic fields, which are classified under the category of non-ionizing radiation, on living things. In particular, the present invention relates to a three-dimensional integrating magnetometer that measures the magnetic field intensity regardless of the direction of the magnetic field and measures the integral value of the magnetic field intensity.

[Prior Art] Generally, a magnetometer called a flux 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. , or large-scale nuclear fusion experimental equipment such as LHD, the magnetic field used is 1
It reaches up to ~5T (Tesla), and the leakage magnetic field around it is too large to be ignored.

The effects of magnetism on the environment or the human body have not yet been investigated in detail. However, 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, static magnetic fields: 2. Do not exceed ST.

Time-varying magnetic field: 20 if the changing time is 10ms or more
Do not exceed T/S-rms.

If the change time is less than IQms (dB/dt)”t＜4゜ High frequency: Absorption rate in the whole body is 0.4-·kg-l or less.

Workers' radiation exposure: Long term - whole body 0.02T, arms 0, 2
T.

Within 15 minutes - whole body 0.2T, hands Arm 2T.

Also, according to the guidelines of the US Food and Drug Administration (FDA), static magnetic fields: Exposure of all or part of the body to no more than 2 guns.

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

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

Exposure of workers (U.S. Department of Energy tentative proposal): 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 the current 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 even if the field is relatively weak. However, even if you take such precautions, there are many opportunities to be exposed to magnetic fields of various strengths under various conditions, and it is important to know how much magnetic field you have been exposed to in total, especially if you work in a magnetic field environment. This is absolutely necessary for those who do. 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.

[Problems to be solved by the invention] Conventional flux meters called fluxgates can only measure instantaneous magnetic flux, so there is a problem that the total magnetic flux cannot be measured over a long period of time. When trying to measure , continuous measurement is required, which results in a large measurement current, making it impossible to achieve power savings.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a portable magnetometer that uses three-dimensionally arranged detection elements to count the integral value of the amount of exposed magnetic flux. The method has a configuration including a timing generation means for determining the timing of the detection elements arranged three-dimensionally and an operation control means for controlling the operation of the amplification means for amplifying the respective detection outputs, and measurement points to be measured at each measurement period. By using linear approximation, we aim to reduce current consumption and reduce calculation errors after measurement.

[Function] In the portable magnetometer configured as described above that counts the integral value of the amount of exposed magnetic flux, the detection elements arranged three-dimensionally are time-divisionally driven for each measurement period to reduce current consumption. By doing so, the operating time of the built-in battery can be extended.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. X
The axis detection means 1 detects the magnetic flux in the X-axis direction, and the X-axis amplification means 2 amplifies the signal from the X-axis detection means 1. The X-axis detection means 3 detects magnetic flux in the Y-axis direction. The Y-axis amplification means 4 amplifies the signal from the X-axis detection means 3. X-axis detection means 5
detects the magnetic flux in the z-axis. The Z-axis amplifying means 6 amplifies the signal of the X-axis detecting means 5, and the operation control means 7 amplifies the signal of the X-axis detecting means 1, the X-axis detecting means 3, and the Z@ detecting means 5 from the signal of the timing generating means 12. the X-axis amplification means 2;
The Y-axis amplification means 4 and the Z-axis amplification means 6 are controlled. The multiplexer 8 selects the output signals of the three amplification means 2, 4, 6 according to the control signal 18 of the operation control means 7. The A/D conversion means 9 converts the analog signals of the three amplification means 2, 4 and 6 outputted from the multiplexer 8 into digital values according to the control signal 22 of the operation control means 7.

FIG. 2 shows a control signal 18 outputted from the operation control means 7.
The time chart for 19.20.21.22 is shown.

The control signal output from the operation control means 7 is transmitted to the oscillation circuit 1.
0 output signal is divided by the frequency dividing circuit 11 and generated from the output signal of the timing generating means 12 which generates the timing of the measurement period from the output signal of the frequency dividing circuit 11 and the output signal of the frequency dividing circuit 11. Ru.

The calculating means 13 converts the digital signal from the A/D converting means 9 into magnetic field strength, and calculates the actual magnetic field strength from the magnetic field strength components of the x, y, and z axes.

Figure 3 shows a diagram in which the magnetic field strength is broken down into three axes (X, Y, Z). Magnetic field strength (magnetic flux density) according to Figure 3
B is: B=((Bx"+By"+Bz")(1 formula)% formula% Furthermore, the calculation means 13 calculates the magnetic field strength B1 calculated by the above formula 1 and data measured after a certain measurement period. Then, the magnetic field strength B2 calculated by the calculation means 13 and the integral value surrounded by the time of the measurement period are calculated, added to the contents of the integrated value storage means 14, and stored again.

FIG. 4 shows an example of the integration method, the integration value storage means 1
4 stores the magnetic flux amount Bh, and the magnetic flux amount B
h is Bh-Σ[((Bn+Bn+1)xhl/2](2
Formula) In formula 2, Bh = magnetic flux amount Bn - magnetic field strength at a certain measurement point Bn+1 = Bn
The magnetic field strength after a certain measurement time h = measurement time.

The contents of the integrated value storage means 14 and the frequency dividing circuit 11
The contents of the time counting means 15 which counts the output signals of and counts the total measurement time from the start of measurement.

It is displayed on the display device 17 via the display control means 16.

FIG. 5 shows an embodiment of the detection means and amplification means according to the present invention.
, a current control resistor R1, and a transistor Tri are connected in series. The two output terminals of the magnetic detection element 23 are connected to an amplifier 24 via amplifying resistors R2 and R3.
Enter.

The + input terminal of the amplifier 24 is grounded via a resistor R4, and the - input terminals are negatively fed back 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 VOut is expressed as Vout=R5(Vinl-Vin2)/R4 (Equation 3), where R5/R4 is the amplification factor. transistor T
r2 is connected between the power terminal of the amplifier 24 and ground. The transistor Tr1. The gate terminal of Tr2 is controlled by the control signal 19 outputted from the operation control means 7, and during measurement, the control signal 19 outputs "H" and is in an ON state, thereby controlling the X-axis detection means 1 and the X-axis amplification. The means 2 is brought into operation. Further, by setting the output of the control signal 19 to "L", the device is brought into a non-operating state and the operating current is cut. The X-axis detection means 3 and the Y-axis amplification means 4
, the X-axis detection means 5, and the Z-axis amplification means 6 have similar configurations.

Next, a block diagram of an embodiment of the present invention controlled by a microcomputer shown in FIG. 6 will be explained.

As shown in FIG. 6, a program memory (ROM) 28. Data memory (R
AM) 29 etc. constitute a microcomputer.

The logical operation processing circuit 27 is composed of an ALU, an operation register, an instruction decoder, etc., and is connected to peripheral circuits by a data bus and address buses 32 and 33.

The ROM 28 is a program memory that stores software in which processing procedures are replaced with instructions.

The RAM 29 is a data memory and is used to temporarily store various information.

The system clock generation circuit 25 receives the output of the oscillation circuit 10 and generates a system clock necessary for the operation of the logic operation processing circuit 27.

The interrupt control circuit 26 receives the output of the frequency dividing circuit 11 that divides the output of the oscillation circuit 10, and generates an activation signal for starting the operation of the logical operation processing circuit 27, and the contents of the interrupt are as follows. It is read out via data bus 32.

The output signal of the frequency dividing circuit 11 is generated from the output signal of the timing generating means 12 which generates the timing of the measurement cycle from the output signal of the frequency dividing circuit 11 and the output signal of the frequency dividing circuit 11. A control signal for the detection means 30 and the reprint means 310 is generated from the output signal. The detection means 30 detects each of the x, y, and
The X-axis detection means 1.3.5 are collectively referred to as the X-axis detection means 1.3.5, and similarly, the amplification means 31 is
This is a general term for the Y and Z axis amplification means 2.4.6. The output of the amplification means 31 is selected by the multiplexer 8, converted into a digital signal by the A/D conversion means 9, and read into the logic operation processing circuit 27 via the data bus 32. The display control means 16 supplies information supplied via the data bus 32 to the display device 17.

The operating procedure when controlled by the microcomputer shown in FIG. 6 will be explained with reference to the flowchart shown in FIG. 7 showing the operating procedure of the present invention.

When an interrupt occurs from the interrupt control circuit 26 to the logical operation processing circuit 27, when X-axis drive is selected for the operation control means 7 in process 71, the control signal 19 shown in FIG. 1 is output. The X-axis detection means 1
, the X-axis amplifying means 2 is driven. The multiplexer 8 selects the output signal of the X-axis amplification means 2. Processing 7
2 for a certain period of time until the operation of the amplifying means becomes stable.
AIT is performed, and in process 32, the A/D conversion means 9
is operated, the converted data is read into the logical operation processing circuit via the data bus 32, and is temporarily stored in the RAM 2B. When Y-axis drive is selected for the operation control means 7 in process 74, the first control signal 20 is output, and the Y-axis detection means 3 and the Y-amplification sub-means 4 are driven. The multiplexer 8 selects the output signal of the Y-axis amplification means 4. WATT for a certain period of time until the operation of the amplification means stabilizes in process 75.
In step 76, the A/D conversion means 9 is operated, the converted data is read into the logic operation processing circuit 27 via the data bus 32, and once the R
Store in AM2B. When Z-axis drive is selected for the operation control means 7 in process 77, the control signal 21 shown in FIG. 1 is output, and the X-axis detection means 5 and the Z-axis
The shaft increasing means 6 is driven. The multiplexer 8 selects the output signal of the Z-axis amplification means 6.

In process 78, a WAIT period is performed for a certain period of time until the operation of the reprinting means stabilizes, and in process 79, the A/D conversion means 9 is operated, and the data converted via the data bus 32 is subjected to the logical operation processing. The data is read into the circuit 27 and temporarily stored in the RAM 28. In process 80,
The digital signal data in the x, y, and z axis directions is converted into magnetic field strength, and ((Bx2+Byz +Bz
z). In process 81, + (Bn-1+Bn)Xh, which is the integral value of the magnetic field strength Bn calculated in process 8o, the previously measured Bn-1, and the measurement period
Perform the calculation of l /2. In process 82, the result calculated in process 81 is added to the integrated value storage means 14 and stored again. In process 83, the time of the measurement cycle is added to the time counting means 15 and stored again. In process 84, the display process is performed on the display device 17, and the process returns to the HALT state in process 85.

[Effects of the Invention] As explained above, the present invention provides a portable magnetometer that counts the integral value of the amount of exposed magnetic flux, which includes a timing generation means for determining the timing of the measurement cycle and a three-dimensionally arranged detection means. By using a configuration that includes an operation control means that controls the operation of the amplification means that amplifies each detection output, it is possible to reduce current consumption, extend the operating time of the built-in battery, and This has the effect of reducing calculation errors with respect to the amount of change in magnetic field strength.

[Brief explanation of drawings]

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,
Figure 3 shows magnetic field strength broken down into three axes (X, Y, and Z axes), and Figure 4 shows integration method 1.
FIG. 5 is a circuit diagram showing an embodiment of the present invention of the detection means and amplification means, FIG. 6 is a PSO logic diagram showing an embodiment of the present invention controlled by a microcomputer, and FIG. 7 is a diagram showing an embodiment of the present invention. It is a flowchart showing an operation procedure. 1-X-axis detection means 2-X-axis amplification means 3-Y-axis detection means 4-Y-axis amplification means Z-axis detection means 6
Z-axis amplification means operation control means 8 Multiplexer A/D conversion means oscillation circuit 11- Frequency division circuit timing generation means calculation means 14 Integrated value storage means Time counting means Display control means 17- Display device 19.20.21.22-Control Signal detection element 24 Amplifier system clock generation circuit Interrupt control circuit Logical operation processing circuit ROM 29-RAM Detection means 31 Amplification means data bus 33-Address bus Applicant Seiko Electronics Co., Ltd. Agent Patent attorney Takayuki Hayashi Baiei Dokou Tajiku (Kari Y Otodera Yu)) Tsutsutonzukeme (7
') Princess Ga-iJ's 1,000-face 4th book (Preliminary shoulder-ji, 〉Item Nakarigihi RΣ's incurable date 1 month 1 month 1') 1 time 2 shaku steps 1 figure 5 Kunidai (,:)

Claims (5)

[Claims] (1) In a three-dimensional integrating magnetometer that measures the integral value of magnetic field strength, (a) three magnetic detection elements arranged three-dimensionally in the X-axis, Y-axis, and Z-axis directions; (b) the above three (c) an operation control means for controlling the operations of the magnetic detection elements and the amplification means; (d) a control signal for the operation control means; (e) A/D conversion means for converting the analog signal output from the multiplexer into a digital signal; and (f) generating a measurement period. Timing generating means (g) calculates a vector of the first magnetic field strength from the digital signals in the three axis directions, and calculates the first magnetic field strength vector after a time that is a measurement interval of the timing generating means.
calculation means for calculating a vector of the second magnetic field strength from the digital signal in the axial direction and calculating an integral value surrounded by the time that is the measurement interval of the timing generation means and the first and second magnetic flux intensities; A three-dimensional integrated magnetic flux meter comprising h) integrated value storage means for storing the sum of the integrated values of the time and magnetic flux intensity; and (i) 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 element is a Hall element. (3) Claim 1, wherein the magnetic detection element 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 time-divisionally drives the three detection elements and their corresponding amplification means. (5) The three-dimensional integrated flux meter according to claim 1, wherein the operation control means cuts off current between the three detection elements and their corresponding amplification means when not measuring.