JPH10170663A - Magnetic field detector and clock with magnetic field measuring function using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic field measuring device which can precisely measure magnetic field information such as azimuth even when a component such as a battery which is large in volume and high in permeability is arranged with a magnetic sensor in the device body, and an electronic clock with magnetic field measuring function including the device. SOLUTION: A pointer-type electronic clock with magnetic field measuring function has a component such as a battery which is large in volume and high in permeability arranged with a magnetic sensor 4 in its body. In this structure, this component changes magnetic field vectors in the area where an MR element of the magnetic sensor 4, causes phase of sensor output to shift, and gives error to azimuth angle derived from the output. Such error is corrected with correcting means 112 (correction table).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic field measuring device for measuring magnetic field information such as azimuth and magnetic strength, and an electronic timepiece provided with the magnetic field measuring device.
More specifically, the present invention relates to a technique for removing a magnetic influence exerted on a magnetic sensor by a component having high magnetic permeability such as a battery disposed together with a magnetic sensor in an apparatus main body.

[0002]

2. Description of the Related Art As shown in FIG. 9, a pair of MR elements 11X + and 11X- which are arranged in the same direction to detect an X-direction component of terrestrial magnetism, and have the same characteristics as those elements, are used for azimuth measurement. It is common to use a magnetic sensor device 4 which is arranged in a direction orthogonal to the MR elements 11X + and 11X- and has MR elements 11Y + and 11Y- for detecting a Y-direction component of geomagnetism. Here, the MR element 11
X +, 11X-, 11Y +, and 11Y- are driven at a constant voltage in a state where resistors 12 having the same resistance value are connected in series,
A bias magnetic field of equal magnitude is applied from a bias coil or the like. However, the direction of the bias magnetic field is opposite between the MR elements 11X + and 11X-, and
The direction of the bias magnetic field is reversed between 1Y-. Therefore,
In the magnetic sensor circuit having this configuration, the MR element 11X
+, 11X−, and the MR elements 11Y +, 11Y− respectively detect geomagnetic components, a change in the midpoint potential corresponding to a change in their resistance is output via the differential amplifier circuit 13 to the sensor output (X output, Y output). ). Moreover, since a bias magnetic field is applied to each of the MR elements 11X +, 11X-, 11Y +, and 11Y-, a relatively large sensor output can be obtained even if there is a slight change in the geomagnetic component as shown in FIG. . At this time, the mutually orthogonal MR
The elements 11 are separately provided with terrestrial magnetic components HE in directions orthogonal to each other (this direction is defined as an X component and a Y component).
Is detected, and a midpoint potential corresponding to the detected is generated. Accordingly, the sensor outputs of the X component and the Y component detected in this manner and the azimuth indicate a relationship as shown in FIG. 11, and therefore, the following equation θcal = arctan (Y output / X output) θ) can be detected.

[0003]

However, when a portable device having such an azimuth measuring function is to be constructed, a magnetic sensor is provided in a main body of the device together with a component having a large volume and a high magnetic permeability such as a battery. And such a component is
This changes the magnetic field vector of the portion where the R elements 11X +, 11X-, 11Y +, and 11Y- are placed. Therefore, X
A phase shift as shown by a dotted line in FIG. 12 occurs in the relationship between the sensor output of the component and the Y component and the azimuth angle. There is a problem that an error as shown is generated.

Japanese Patent Laid-Open Publication No. Hei 6-300869 discloses a layout in which electronic components are separated from a magnetic sensor, and Japanese Laid-Open Utility Model Publication No. 61-48389 discloses a layout in which magnetic effects are canceled. It is disclosed. However, there is not enough space in a portable device to adopt the layout disclosed in the above publication. Therefore, all components cannot be arranged in the apparatus main body, and the magnetic sensor must be provided in a portion protruding from the apparatus main body, and there are great structural and design restrictions.

[0005] In view of the above problems, an object of the present invention is to provide:
A magnetic field measurement device that can accurately measure magnetic field information such as the direction even if a large volume and high permeability component such as a battery is placed together with a magnetic sensor inside the device body,
And an electronic timepiece having a magnetic field measurement function provided with the same.

[0006]

In order to solve the above-mentioned problems, in a magnetic field measuring apparatus according to the present invention, an apparatus main body, a magnetic sensor disposed in the apparatus main body, and a detection result of the magnetic sensor are used. Sensor control means for obtaining magnetic field information such as direction, and removing the magnetic influence exerted on the magnetic sensor by a component having a high magnetic permeability such as a battery disposed in the apparatus body from the magnetic field information obtained by the sensor control means. And a correction means for performing correction.

In a magnetic field measuring device, when a component having a large volume and a high magnetic permeability such as a battery is arranged together with a magnetic sensor in the device main body, the component changes the magnetic field vector of a portion where the MR element is placed. Even if a measurement error of the azimuth angle caused by the phase shift of the sensor output is generated, the present invention includes a correction unit for correcting such an error. Therefore, even if components having a large volume and a high magnetic permeability such as a battery are arranged together with the magnetic sensor in the apparatus main body, it is possible to accurately measure the magnetic field information such as the azimuth.

In the present invention, the correction means includes:
It is possible to use a correction table for converting the magnetic field information calculated by the sensor control unit based on the detection result of the magnetic sensor into a value from which the influence of the component has been removed.

Such a magnetic field detecting device is, for example, a magnetic field information display means for displaying magnetic field information obtained by the magnetic field detecting device, a time display member, and a time display for driving the time display member. The present invention can be used for an electronic timepiece having a magnetic field measurement function having a step motor.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A typical embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an electronic timepiece having a magnetic measurement function to which the present invention is applied.

The pointer-type electronic timepiece 1 having the magnetic measurement function shown in FIG. 1 can be used as a so-called compass in addition to a normal time display. That is, in the pointer-type electronic timepiece 1 of the present embodiment, in addition to the time display two-pole step motor 3 for driving the time display hands (time display member / not shown) inside the apparatus main body 2. Also, a magnetic sensor device 4 and a step motor 5 for magnetic direction display (magnetic field display) for displaying a magnetic direction (magnetic field information) obtained from the detection result of the magnetic sensor device 4 by a needle (not shown) for magnetic direction display. Step motor / magnetic field information display means)
Is built-in. The driving source of these components is a button-type battery 6 built in the apparatus main body 2. Switches 7B to 7E for executing various functions are provided on the outer peripheral side of the apparatus main body 2 in addition to a switch 7A for performing normal time adjustment. In the following description, it is assumed that pressing the switch 7E among the switches 7A to 7E displays the azimuth.

In the pointer-type electronic timepiece 1 configured as described above, the configuration of the magnetic sensor device 4 will be described with reference to FIGS.
, The detailed description is omitted, but in the magnetic sensor device 4, the MR element 11X shown in FIG.
+, 11X− and the MR elements 11Y +, 11Y− are arranged in a direction orthogonal to each other, and the respective MR elements 11X +, 11X
A predetermined bias magnetic field is applied to −, 11Y +, and 11Y−. Therefore, in the magnetic sensor circuit having this configuration, the MR elements 11X + and 11X− and the MR element 11X +
Since Y + and 11Y- generate a midpoint potential corresponding to the geomagnetic component HE corresponding to the position, the azimuth can be obtained based on the X output and Y output obtained from each differential amplifier circuit 13.

FIG. 2A is a functional block diagram showing the configuration of a pointer-type electronic timepiece with an azimuth measuring function according to this embodiment, and FIG. 2B is a block diagram showing an example of the hardware configuration.

As shown in FIG. 2A, in the pointer type electronic timepiece of the present embodiment, the oscillating means 101 and the oscillating means 101
Frequency dividing means 102 for frequency-dividing a signal from the frequency divider to obtain a signal of a predetermined frequency, and mechanical display means 105 such as a time display pointer based on the signal from the frequency dividing means 102.
And a time display motor control means 103 for controlling the drive of the time display two-pole step motor 3 for driving the motor. Also, a magnetic sensor device 4 for detecting a magnetic field for measuring an azimuth, a sensor control means 110 for obtaining an azimuth based on a detection result of the magnetic sensor device 110, and an azimuth obtained by the sensor control means 110 are displayed. And magnetic field information display means 111 for this purpose. Further, in the present embodiment, an input means 106 (corresponding to the switch 7E in FIG. 1) for inputting a command to obtain the azimuth, and a command to obtain the azimuth via this input means 106 A timing control means 107 for synchronizing the drive of the time display two-pole step motor 3 with the measurement of the magnetic field by the magnetic sensor device 4 when there is an error. Here, the timing control means 107 and the like
It is composed of a microcomputer that operates according to a program stored in the OM or the like, and controls the overall control of the pointer-type electronic timepiece.

In the pointer type electronic timepiece of this embodiment, the polarity of the rotor for time display is determined based on the polarity of the driving pulse for the step motor. Means 1
08 is configured. That is, the polarity of the drive pulse output by the time display motor control means 103 changes depending on the state of the pole position of the rotor of the time display two-pole step motor 3. The pole position of the rotor can be determined. The time display motor polarity determination means 108
The configuration may be such that the pole position of the rotor is determined based on whether the current drive for the time display two-pole step motor 3 is an odd-numbered step drive or an even-numbered step drive from the reference state. That is, the time display two-pole step motor 3
Since the pole position of the rotor is inverted every pulse based on the drive pulse generated by the time display motor control means 103, the pole position of the rotor depends on whether the current drive is an even or odd step from the reference state. Can be determined.

Further, in this embodiment, the sensor control means 11
With respect to 0, a correction means 11 for removing the influence of a high magnetic permeability component such as a battery 6 arranged together with the magnetic sensor device 4 in the device main body 2 on the measurement result such as the azimuth.
2 are configured. The correction means 112 is constituted by a correction table for converting the azimuth calculated by the sensor control means 110 based on the detection result of the magnetic sensor device 4 into a value from which the influence of the battery 6 or the like is removed.

That is, the correction table constituting the correction means 112 is the same as the correction table described with reference to FIGS.
3 is a look-up table for eliminating an azimuth error caused by a phase shift between sensor outputs of the Y component and the Y component. As shown in FIG.
(Deg) and the correction value errcal (deg) are stored in a RAM or the like. Here, the measured value θcal is an azimuth calculated from the sensor output itself obtained by the magnetic sensor device 4, and the correction value errcal (deg) is the battery 6 included in the sensor output obtained by the magnetic sensor device 4. This is a value for eliminating magnetic influences such as the above, and is obtained from the following approximate expression errcal = 9 · cos (2θ) corresponding to the relationship between the azimuth angle and the measurement error shown in FIG.

Therefore, when the sensor control means 110 calculates the azimuth, the correction value errca is used for the measured value θcal.
By using l and the following equation, the corrected azimuth angle θ = θcal−errcal is also calculated to calculate the corrected azimuth angle θ (azimuth angle after removing the magnetic influence of the battery 6 and the like). be able to.

According to the corrected azimuth angle θ obtained in this manner, as shown in FIG. 4, the relationship between the measurement error before and after the correction and the azimuth angle is reduced to an error within 1 deg over an azimuth angle of 0 to 360 deg. It is possible to increase the measurement accuracy of the azimuth angle.

Note that the pointer-type electronic timepiece of this embodiment has a structure shown in FIG.
A hardware configuration as shown in the block diagram of FIG. That is, the pointer-type electronic timepiece includes an oscillation circuit 201 and a frequency dividing circuit 202 for dividing a signal from the oscillation circuit 201 to obtain a signal of a predetermined frequency. The time display 2 shown in FIG.
The pole step motor control means 103 controls the time display two-pole step motor 20 based on a signal from the frequency dividing circuit 202.
5 (corresponding to the time display two-pole step motor 3 in FIGS. 1 and 2A), and a time display two-pole step based on the drive pulse. Motor 205
And a motor drive circuit 204 for driving the motor. Also,
For the motor drive circuit 204, a time display motor polarity determination means 206 for determining the pole position of the rotor of the time display two-pole step motor 205 is configured. Also,
The timing control means 107 and the correction means 112 shown in FIG. 2A include a data bus 217 for the motor drive pulse generation circuit 203 and the time display motor polarity determination means 206, a ROM 207 storing an operation program, and the ROM 207. The CPU 208 controls the overall control based on the operation program stored in the RAM 209, a RAM 209 storing various parameters, and an input control circuit 211 that determines an operation of the input unit 210. Further, in addition to the magnetic sensor device 212 (corresponding to the magnetic sensor device 4 in FIGS. 1 and 2B) and the sensor control circuit 213 (sensor control means), a motor drive pulse generation circuit 214 and a motor drive circuit 215, and a step motor 216 for azimuth display, and these motor drive pulse generation circuit 214, motor drive circuit 21
5, and by the step motor 216 for azimuth display,
This constitutes the magnetic field information display means 111 shown in FIG.

The operation of the pointer-type electronic timepiece according to the present embodiment will be described with reference to FIGS. FIG. 5 is a timing chart of signals used in the pointer-type electronic timepiece, and FIGS. 6 and 7.
Is a flowchart showing a process performed based on these signals.

FIGS. 5A to 5E show the output timing T1 of the 1 Hz signal output from the frequency dividing means 102 for moving the second hand, and the time display motor control means 10.
3 to the time display two-pole step motor 3, the output timing T 2 of the motor drive pulse, and the output timing T of the command signal when there is a switch input from the input means 106.
3. A timing T4 at which a measurement execution waiting flag is set based on the command signal, a timing T5 at which the azimuth is measured, and the azimuth of the magnetic field information displaying means 111 from the sensor control means 111 to display the azimuth. The timing T6 at which a motor drive pulse is output to the display step motor is shown. When there is a command to measure the azimuth based on these signals,
As will be described later, the driving of the time display two-pole step motor 3 and the detection of the magnetic field by the magnetic sensor device 110 are performed at a predetermined timing while synchronizing them.

In the pointer type electronic timepiece according to this embodiment,
Operation (command) to obtain direction from switch 7E
When the pole position of the rotor of the time display two-pole step motor 3 is in one state, the azimuth is measured only when the pole position of the rotor is in the other state. The azimuth measurement is configured to be postponed until the state is reached. That is, the azimuth is measured only when the north and south poles of the rotor of the step motor are in the specific directions. In the following description, the time display motor polarity determination means 108
Is output when the pole position of the rotor of the two-pole step motor 3 for time display is in one state (a state in which the azimuth should be measured), and the pole position of the rotor is in the other state (the state of the azimuth). The output is “1” when the measurement is to be stopped).

In the pointer type electronic timepiece of this embodiment, as shown in FIG. 6, a switch input process is performed from the input means 106 in step ST401, and a step ST402 is performed.
When it is determined that there is a switch input in step ST403
After setting “1” to the measurement execution waiting flag in
The process proceeds to another process (step ST404).

After such input processing is performed, FIG.
As shown in (2), if it is determined in step ST405 that there is a timer interrupt, and it is determined in step ST406 that this timer interrupt is a 1 Hz interrupt (interrupt for moving the second hand) from the frequency dividing means 102, in step ST407, time Display motor control means 103
Outputs one motor drive pulse to the time display two-pole step motor 3. Thus, each time one motor drive pulse is output, the rotor rotates and the pole position is reversed, and the second hand advances by one step.

Next, in step ST416, it is determined whether or not "1" is set to the measurement execution waiting flag. Here, if it is determined that “1” has been set to the measurement execution waiting flag, it is determined whether or not the output of the time display motor polarity determination unit 108 is “0” in step ST408. That is, the pole position of the rotor of the time display two-pole step motor 3 is confirmed.

Here, the time display motor polarity determining means 1
08 is "0", the process proceeds to step ST.
After performing the measurement of the magnetic field by the magnetic sensor device 4 in 409, the sensor control unit 110 proceeds to step ST41.
At 0, the direction is determined from the measured value. At this time,
If the azimuth is determined as it is from the measurement result of the magnetic field by the magnetic sensor device 4, the error includes the error described with reference to FIGS. 12 and 13. The correction table shown (correction means 11
Correction is performed according to 2).

Next, in step ST411, the position of the pointer for displaying the corrected orientation is calculated, and in step ST412, the difference between the calculated hand position and the current hand position is calculated. In step ST413, step ST412
The number of motor drive pulses corresponding to the difference obtained in step (1) is output from the sensor control means 110 to the step motor for azimuth display of the magnetic field information display means 111, and the azimuth measurement result is displayed on the magnetic field information display means 111. Then, step ST4
In step 14, “0” is set to the measurement execution waiting flag,
The process proceeds to another process (step ST415).

If it is determined in step ST406 that this timer interrupt is not a 1 Hz interrupt even if there is a timer interrupt in step ST405, it is determined in step ST416 that "1" is not set to the measurement execution waiting flag. And step ST408
And the output of the time display motor polarity determining means 108 is "0".
If not (the pole position of the rotor of the time display two-pole step motor 3 is in the other state, the measurement of the azimuth should be stopped), the process proceeds to another process (step ST415).

As described above, in the pointer-type electronic timepiece according to the present embodiment, since the large-volume and high-permeability parts such as the battery 6 are arranged together with the magnetic sensor device 4 in the device main body 2, the battery 6 and the like are arranged. Is the MR element 1 of the magnetic sensor device 4
1X +, 11X-, 11Y +, 11Y- (see FIG. 9)
In the present embodiment, even if the magnetic field vector of the portion where is placed changes and a phase shift of the sensor output occurs, the correcting means 112 corrects the azimuth error caused by such a phase shift. Therefore, even if the magnetic sensor device 4 and the battery 6 are arranged together in the device main body 2, the direction can be measured accurately. Therefore, as shown in FIG. 8, the pressure sensor 8 and the pressure display step motor 9 for displaying the pressure with the pressure display pointer (not shown) are further arranged in the apparatus main body 2, so that the battery Even in the case where the pressure sensor 8 in addition to the magnetic sensor 6 has a magnetic influence on the magnetic sensor device 4, an accurate direction can be obtained only by configuring the correction means 112 (correction table) corresponding to the magnetic sensor device 4.

[Other Embodiments] In each of the above-described embodiments, an example has been described in which an azimuth is measured as magnetic field information. However, as long as measurement is performed via a magnetic sensor, the present invention is not limited to the azimuth. The function of measuring the magnetic field strength may be mounted on the pointer-type electronic timepiece.

Further, in the case of displaying magnetic field information such as azimuth, an example has been described in which a pointer is displayed using a step motor for azimuth display, but the azimuth is displayed digitally using a liquid crystal display device or the like. Is also good.

[0034]

As described above, in the magnetic field measuring apparatus according to the present invention, when a component having a large volume and a high magnetic permeability, such as a battery, is arranged together with the magnetic sensor in the apparatus main body, However, even if the magnetic field vector of the portion where the MR element is placed is changed to cause a phase shift in the sensor output, the correcting means corrects an error such as an azimuth angle caused by such a phase shift. Therefore, according to the present invention, it is possible to accurately measure the azimuth and the like even when a component having a large volume and a high magnetic permeability such as a battery is arranged together with the magnetic sensor in the apparatus main body.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a pointer-type electronic timepiece with a magnetic measurement function to which the present invention is applied.

FIG. 2A is a functional block diagram of a pointer-type electronic timepiece having an azimuth measuring function to which the present invention is applied, and FIG. 2B is a block diagram showing an example of a hardware configuration thereof.

FIG. 3 is an explanatory diagram of a correction table constituting the correction means shown in FIG. 2;

4 is a graph comparing an error after correcting the azimuth angle using the correction table shown in FIG. 3 with an error before the correction.

FIG. 5 is a timing chart of each signal used in the pointer type electronic timepiece shown in FIG. 2;

FIG. 6 is a flowchart showing a switch input process in the pointer-type electronic timepiece shown in FIG. 2;

FIG. 7 is a flowchart showing a hand movement process and an azimuth measurement process in the pointer-type electronic timepiece shown in FIG. 2;

8 is a schematic configuration diagram when a pressure sensor and a step motor for displaying pressure are added to the pointer-type electronic timepiece shown in FIG. 2;

FIG. 9 is an explanatory diagram showing a basic principle of a magnetic sensor used for azimuth measurement.

FIG. 10 is an explanatory diagram showing a sensor output when a magnetic sensor used for azimuth measurement is biased.

FIG. 11 is an explanatory diagram of sensor outputs of two directions components obtained from a magnetic sensor when performing azimuth measurement.

FIG. 12 is an explanatory diagram showing a phase shift generated in a sensor output due to a magnetic influence from a battery disposed in the same device when performing azimuth measurement using a magnetic sensor.

FIG. 13 is an explanatory diagram showing a measurement error of an azimuth angle caused by a phase shift shown in FIG. 12;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electronic timepiece 2 Device main body 3 Time display two-pole step motor 4 Magnetic sensor device 5 Direction display step motor 6 Battery 7A-7E switch 8 Pressure sensor 9 Pressure display step motor 11X +, 11X-, 11Y +, 11Y-MR element REFERENCE SIGNS LIST 12 resistance 101 oscillating means 102 frequency dividing means 103 time display motor control means 106 input means 107 timing control means 108 time display motor polarity determination means 110 sensor control means 111 magnetic field information display means 112 correction means (correction table) 201 oscillation circuit 202 frequency divider circuit 203 motor drive pulse generation circuit 204 motor drive circuit 205 time display two-pole step motor 206 time display motor polarity determination means 207 ROM 208 CPU 209 RAM 210 input means 211 input control circuit 12 magnetic sensor device 213 step motor 217 data bus for sensor control circuit 214 motor drive pulse generating circuit 215 a motor drive circuit 216 azimuth display

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G04G 1/00 315 G04G 1/00 315J

Claims (3)

[Claims] 1. An apparatus main body, a magnetic sensor disposed in the apparatus main body, a sensor control means for obtaining magnetic field information such as an azimuth based on a detection result of the magnetic sensor, and a sensor control means disposed in the apparatus main body. A magnetic field detection device comprising: a correction unit that corrects a magnetic effect of a high magnetic permeability component such as a battery on the magnetic sensor from magnetic field information obtained by the sensor control unit. 2. The correction table according to claim 1, wherein the correction means converts the magnetic field information calculated by the sensor control means based on the detection result of the magnetic sensor into a value from which the influence of the component has been removed. A magnetic field detection device comprising: 3. A magnetic field detection device as defined in claim 1 or 2, a magnetic field information display means for displaying magnetic field information obtained by the magnetic field detection device, a time display member, and driving the time display member An electronic timepiece with a magnetic field measurement function, comprising: