JPH06281463A - Electronic azimuth meter - Google Patents

Abstract

PURPOSE:To enable errors in detected output due to the magnetization of a device itself and the like to be easily corrected by correcting output signals detected by a geomagnetism detection means, and thereby letting an azimuth computing means obtaining azimuth out of the corrected signals, be equipped. CONSTITUTION:A wave synthesizing circuit 10 outputs an interrupt signal for starting reading and processing data and the like to a CPU 11. The CPU 11 starts reading and processing data from a register 7, that is, detected output signals. A RAM 13 stores the various kinds of data under the control of the CPU 11, and concurrently reads those data so as to forward them the CPU 11. And the CPU 11 controls the respective sections of an electronic azimuth meter in accordance with programs within a ROM 12. For example, a detected output signal corresponding to voltage vs from an amplifying circuit 5, is corrected so as to allow data to be computed, and concurrently the azimuth of an measuring object is computed so as to be housed in the RAM 13, so that computed azimuth is thereby be indicated over a display section DS. Thus as mentioned above, errors in detected output can easily be corrected, so that azimuth can thereby be computed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic azimuth meter capable of accurately recognizing a desired direction by detecting geomagnetism.

[0002]

2. Description of the Related Art Conventionally, a magnetic sensor having two magnetic detection directions orthogonal to each other is provided, and an output corresponding to the strength of the two magnetic detection direction components of the earth magnetism is obtained by the magnetic sensor. There is an electronic azimuth meter that calculates the azimuth based on the output. In addition, in this type of electronic azimuth meter, in order to accurately detect the direction and magnitude of the earth's magnetism, a bias coil that is orthogonal to the magnetic sensor is wound, and this bias coil is used to detect the direction and the magnitude of two orthogonal directions. It has been proposed to detect geomagnetism with a bias magnetic field applied.

[0003]

By the way, in the conventional electronic azimuth meter as described above, it is necessary to correct an offset due to magnetization of the device itself, that is, a non-negligible measurement error. Therefore, the applicant of the present application has previously proposed a method of correcting a measurement error due to magnetization (Japanese Patent Application No. 4-151565).
issue). That is, the electronic azimuth meter itself is rotated once while keeping horizontal, and the detection outputs in the two magnetic detection directions orthogonal to each other are obtained in all directions, and the maximum value of these detection outputs, that is, the first and second maximum detections are obtained. Remember the output,
A method of correcting the obtained detection output by the first and second maximum detection outputs during the azimuth measurement was considered. However, in the correction method as described above, every time the user thinks that the device itself has been magnetized, the device performs one rotation measurement to update the first and second maximum detection outputs. It is necessary to memorize it, and in particular, the measurement of making one rotation while keeping the apparatus horizontal was a troublesome work. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electronic azimuth meter capable of correcting an error in a detection output due to magnetization of the device itself by an easy operation.

[0004]

In order to achieve the above object, according to the invention of claim 1, at least a component of the geomagnetism in a first direction and a component of a second direction orthogonal to the first direction are included. The geomagnetism detecting means for outputting the first and second output signals according to the strength, the first and second output signals outputted from the geomagnetism detecting means when directed in a predetermined direction, and the predetermined direction are 180 ° Correction value calculation means for obtaining a correction value from the first and second output signals output by the geomagnetism detection means when facing in the opposite direction, and the geomagnetism detection after the correction value is obtained by the correction value calculation means First and second detected by means
And an azimuth calculating means for calculating the azimuth from the corrected signal. Further, according to the invention of claim 2, the first and second output signals according to the strength of the component of the geomagnetic field in the first direction and the component of the second direction orthogonal to the first direction are output at least. Geomagnetic detection means, an external operation switch, and first and second geomagnetic detection means output when the external operation switch is operated.
Correction signal calculating means for obtaining a correction value from the first output signal and the second output signal output by the geomagnetic detection means when the external operation switch is directed in a direction different from the direction when the external operation switch is operated, After the correction value is obtained by the correction value calculating means, the first and second output signals detected by the geomagnetism detecting means are corrected, and an azimuth calculating means for obtaining an azimuth from the corrected signal is provided. There is.

[0005]

The geomagnetic detecting means obtains the first and second output signals in a predetermined direction, and when the direction is 180 ° opposite to the predetermined direction or different from the predetermined direction. The first output signal and the second output signal when the direction is turned are obtained, and based on these signals, the output signal from the geomagnetism detecting means thereafter is corrected.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on the embodiments shown in the drawings. FIG. 1 shows the configuration of a magnetic sensor 1 used in this electronic compass. This magnetic sensor 1 is, for example, a glass or alumina substrate 1a.
On top, four magnetoresistive elements MR1, MR2, MR3, M
R4 and four pads Pd1, Pd2, Pd3, Pd4
Etc. are formed. These magnetoresistive elements MR1 and M
R2, MR3, and MR4 are formed by, for example, vacuum-depositing a ferromagnetic material such as permalloy on the substrate 1a, and have substantially the same characteristics. Also the pad Pd
1, Pd2, Pd3, and Pd4 are formed by vacuum-depositing a normal wiring material on the substrate 11, for example.

The magnetoresistive elements MR1, MR2, MR
3 and MR4 are arranged so that their magnetic detection directions are orthogonal to the magnetic detection directions of the other magnetoresistive elements MR1, MR2, MR3, and MR4 adjacent to each other.
Each detection direction is formed so as to have an inclination of 45 degrees with respect to the vertical direction of the magnetic sensor 1 in FIG.
Each of these magnetoresistive elements MR1, MR2, MR3, MR4
Form a bridge circuit via the pads Pd1, Pd2, Pd3, and Pd4, and the pads Pd1 and
A predetermined DC voltage V is applied between Pd3. As is generally known, the magnetoresistive elements MR1, MR2, MR3, and MR4 have their resistance values changed by the action of a magnetic field. Therefore, a predetermined DC voltage V is applied between the pads Pd1 and Pd3. In this state, when a magnetic field acts on each magnetoresistive element, its resistance value changes and a predetermined voltage is generated on the pads Pd2 and Pd4. That is, the potential of the pad Pd2 is PS1 and the potential of the pad Pd4 is PS
When it is set to 2, between the pad Pd2 and the pad Pd4,
The potential difference between PS1 and PS2, that is, the output of the magnetic sensor 1 is generated.

Further, two bias coils CL1 and CL2 which are orthogonal to each other are wound around the magnetic sensor 1. The bias coil CL1 generates a bias magnetic field that is phase-reversed in the vertical direction of the magnetic sensor 1 (direction forming 45 ° with respect to the magnetic detection direction of each magnetoresistive element) depending on the direction of the flowed current. The bias coil CL2 generates a bias magnetic field that is phase-reversed in the left-right direction of the magnetic sensor 1 (direction forming a 45 ° angle with the magnetic detection direction of each magnetoresistive element) depending on the direction of the flowed current.

FIG. 2 is a block diagram of an electronic azimuth meter according to this embodiment. This electronic azimuth meter includes a magnetic sensor 1, an amplifier circuit 5, an A / D conversion circuit 6, a register 7, a bias coil. CL1, CL2, a coil drive circuit 9, a waveform synthesis circuit 10, a measurement circuit unit, an oscillation circuit 14a,
A clock unit including a frequency dividing circuit 14b and a time / date counting circuit 14c, and a CPU (Central Processing Unit) 11
And a display section DS and a ROM (Read Only Memory) 12
A RAM (Random Access Memory) 13 and a switch input section SI.

As described above, the magnetic sensor 1 is composed of a bridge circuit section composed of the magnetoresistive elements MR1, MR2, MR3, MR4 and the like, and the potentials PS1 and PS2 of the pads Pd2 and Pd4 thereof are given to the amplifier circuit 5. Amplifier circuit 5
Has a configuration as shown in FIG.
The above-mentioned potentials PS1 and PS2 input from are taken in and the voltage VS described later is output to the A / D conversion circuit 6. The A / D conversion circuit 6 digitally converts the voltage VS input from the amplification circuit 5 and outputs the detection outputs V1 to V4 described later to the register 7
And the register 7 sends the detected output V1
Store V4.

On the other hand, bias currents are supplied from the coil drive circuit 9 to the bias coils CL1 and CL2, respectively. The directions of the bias currents are respectively inverted, so that the magnetic sensor 1 eventually has a bias coil CL1,
By CL2, four kinds of bias magnetic fields of upward, downward, leftward and rightward are given. The coil driving circuit 9 has a configuration as shown in FIG. 4, and the signal P from the waveform synthesizing circuit 10 is used.
1 to P3, N1 to N4, P _C and P _P , the terminals W1 and
The coil CL1, which is connected between W2, the terminal W2,
A bias current is supplied to the coil CL2 connected between W3 (that is, four types of bias magnetic fields are sequentially applied to the magnetic sensor 1 at different timings).

The waveform synthesizing circuit 10 receives a control signal from the CPU 11 and outputs the above various signals to the coil driving circuit 9 and at the same time, a conversion timing signal for instructing the A / D conversion circuit 6 on the timing of A / D conversion. Output Sa. On the other hand, the A / D conversion circuit 6 outputs the in-conversion signal Sb indicating that the A / D conversion is in progress to the waveform synthesis circuit 10. Further, the waveform synthesizing circuit 10 instructs the CPU 11 to start the data fetching process or the like by using the interrupt signal I.
NT is output, and the CPU 11 outputs the data of the register 7 (that is, the detection output V
1) to V4) are started. RA
M13 has a configuration to be described later, and is a circuit unit that stores various data under the control of the CPU 11 and reads the stored data and sends the data to the CPU 11. CP
U11 controls each part of this electronic azimuth meter according to the program in the ROM 12, calculates data X and Y from the detection outputs V1 to V4 corresponding to the voltage VS from the amplifier circuit 5, and at the same time outputs the data X and Y. Based on this, the azimuth of the direction to be measured is calculated and stored in the RAM 13, and the calculated azimuth is displayed on the display unit DS.

The switch input section SI is a switch S described later.
It is a circuit unit that includes 1 to S4 and gives a switch input signal to the CPU 11 when any one of them is operated. The ROM 12 stores various programs as an electronic azimuth meter, such as an azimuth measurement processing program.

The oscillating circuit 14a is a circuit which constantly outputs a signal of a constant frequency, and the frequency dividing circuit 14b divides the above-mentioned signal from the oscillating circuit 14a into a predetermined frequency signal, which is the time / date. This is a circuit for sending to the counting circuit 14c. The time / date counting circuit 14c counts the above signals to obtain the date, time, date and day of the week, and outputs them to the CPU 11
It is a circuit to send to.

The display section DS is a circuit section for displaying various data under the control of the magnetic sensor 1. Also this display section DS
In the center of the circular display panel DP, a main display portion DS1 for displaying the time is arranged, a sub display portion DS2 for displaying the date is arranged below the circular display panel DP, and a 4 × 4 dot matrix display portion is arranged in the upper portion. , Three dot display sections DS arranged in a row
Three are arranged. On the upper left side of the main display section DS1, there is provided a navigation display body NA which is lit and displayed in a navigation mode described later, and the main display section D is also provided.
On the upper right side of S1, a memo display ME that is lit and displayed in a later-described stored data display state is arranged, and further 60 rectangular display bodies 6 ° are provided around the circular display panel DP. Circular display section DS4 arranged radially at intervals
Is provided. 13 for explaining the operation.
As shown in a), the circular display panel DP is arranged on the upper surface of the case of the electronic compass, and a rotating bezel is rotatably attached to the outer peripheral portion of the case. Further, the magnetic sensor 1 of FIG. 1 is provided on the back surface side of the circular display panel DP.
Is attached (therefore, FIG. 1 shows a circular display panel DP).
Is a view of the magnetic sensor 1 viewed from the back surface side of FIG.

FIG. 5 shows the structure of the RAM 13. In the figure, a mode register M is a register for designating a mode, and when the set value is 0, the display unit D
The basic clock mode for displaying the time, date, day of the week, or the direction of travel at that time is designated in S, and when the set value is 1, the direction of the upper side of the display panel of this electronic compass (display panel DP is set to analog 1 when regarded as a clock dial
A direction (2 o'clock direction) is measured, the measurement result is displayed on the display unit DS, and a navigation mode in which the measured direction is stored in any one of navigation memories ME1 to ME5 described later is designated. The measurement flag A is a flag that is set to 1 when measuring the traveling direction and the like and displaying the result on the display unit DS in the basic timepiece mode. The azimuth correction flag L is a flag that is set to 1 when obtaining a correction value for correcting the azimuth measurement result in the navigation mode. When the set value is 0 in the normal state of the navigation mode (states other than the state in which the correction value for the azimuth is obtained) in the normal state of the navigation mode, the memory designation register N designates only the measurement of the traveling direction, On the other hand, when the set value is 1 to 5,
These are registers for designating navigation memories ME1 to ME5 described later, respectively.

The measurement flag B is 1 when the measurement is performed in the normal state of the navigation mode, when the value of the memory designation register N is 0 and only the measurement of the traveling direction is designated. Is the flag that is set. The correction value calculation method register G is a register for designating a method for obtaining the correction value of the above-mentioned azimuth. When 0 is set, a method by two-point correction described later is described, and when 1 is set, it is described later. Specify the method by the north direction correction of. The two-point correction register J measures the azimuth in one direction of the arbitrary direction as the first point when obtaining the correction value by the method of the above-mentioned two-point correction, and thereafter, as the second point, the above-mentioned arbitrary direction. When measuring the azimuth in the other direction, the register is set to 1 when measuring the first point and set to 2 when measuring the second point. The detection count register I is a register that counts the number of detection processes in the azimuth measurement process described later.

The memory V1 has a magnetic sensor 1 and a coil CL.
1 is a memory for storing the detected output V1 that is digitized by the A / D conversion circuit 6 when the bias VS is applied first downward and then upward, and the memory V2 is a magnetic sensor. 1 is a memory for storing the detected output V2, that is, the voltage VS when the bias magnetic field is first applied to the coil CL1 in the upward direction and then to the downward direction, which is digitized by the A / D conversion circuit 6. The memory V3 stores the detection output V3, ie, the voltage VS when the bias magnetic field is applied to the magnetic sensor 1 in the coil CL2 to the left and then to the right, which is digitized by the A / D conversion circuit 6. In the memory V4, the voltage VS when the bias magnetic field is first applied to the magnetic sensor 1 by the coil CL2 in the right direction and then in the left direction is digitized by the A / D conversion circuit 6, that is, the detection output V4 is stored. It is a memory. The memory X is a memory that stores the difference between the detection outputs V1 and V2 stored in the memories V1 and V2, that is, the data X, and the memory Y is the detection output V that is stored in the memories V3 and V4.
This is a memory for storing the difference between 3 and V4, that is, the data Y.

The azimuth data memory D is a memory for storing the azimuth data which is obtained by the azimuth measurement process described later and is not corrected. The post-correction azimuth data memory F is corrected to the azimuth data of the azimuth data memory D. It is a memory for storing the azimuth data after the addition of. The first point X component memory HX1 and the first point Y component memory HY1 are
Geomagnetic X component and Y of the first point (that is, one direction in an arbitrary direction) measured when obtaining the correction value of the point correction
The second point X component memory HX2 and the second point Y component memory HY are memories that store data corresponding to the components.
2 is the second point (that is, the other direction of the above arbitrary direction)
It is a memory for storing the X and Y components of the earth's magnetism. The north correction value memory HK is a memory that stores the correction value by the north direction correction.

The navigation memories ME1 to ME5 are
Each is a memory that stores the traveling direction and the like measured in the above-mentioned navigation mode together with the date and time of measurement.

Next, the operation of this embodiment configured as described above will be described. FIG. 6 is a general flowchart showing an outline of the operation of this embodiment. In step S1,
It is determined whether any switch of the switch input section SI has been operated and there is a switch input. If there is no switch input, the process directly proceeds to step S3. If there is a switch input, the process proceeds to the switch processing of step S2. , The process corresponding to the switch input is executed, and then step S3
Proceed to. Then, in step S3, the data or the like instructed to be displayed at that time is displayed on the display unit DS, but when the process of step S3 is completed, the process returns to step S1.

FIG. 7 is a flow chart showing in detail the switch processing (step S2) in FIG.
Is the azimuth measurement processing in FIG. 7 and the like (for example, step S
19, S29, S35, etc.) in detail, FIG. 9 is a flowchart showing in detail the azimuth correction switch process (step S67) in FIG. 7, and FIG. 10 is a display process (FIG. 6). It is a flow chart which shows step S3) in detail. Also, FIG. 11 and FIG.
FIG. 13 is a diagram for explaining the azimuth measurement process (process shown in the flowchart of FIG. 8), and FIGS.
Reference numeral 4 shows the transition of the display of the display section DS accompanying the operation of various switches. The operation in each state will be described in detail below with reference to these drawings.

(A) Operation in basic clock mode For example, assume that the set value of the mode register M is 0 and the basic clock mode is set. In this case, the display process is repeated as shown in FIG. 6 unless there is a switch input. That is, at this time, in step S130 of FIG. 10, it is determined that the value of the mode register M is 0 and the basic clock mode is set, and in step S131, the main display section DS1 and the sub-display section DS2 of the display section DS are respectively displayed. The current time and date from the time / date counting circuit 14c are displayed and the process proceeds to step S132. Step S1
At 32, it is judged whether the value of the traveling direction measurement flag A is 0, and 0
If so, the process proceeds to step S133, and the dot display section DS3
The day of the week sent from the time / date counting circuit 14c is displayed in step S134, and in the subsequent step S134, the second digit of the current time from the time / date counting circuit 14c is displayed by the rectangular display of the circular display section DS4. . For example, now June 30
When it is 10:58:50 on Sunday and Wednesday, the display on the display unit DS is as shown in a of FIG.

In the above state, the upper portion of the electronic azimuth meter (the circular display panel DP of the display section DS is the 12 o'clock position when it is assumed to be an analog clock character, hereinafter referred to as the upper end of the display section DS. ) Is indicated by a switch S11 as shown in FIG.
To operate. At this time, in response to this operation, the process proceeds from step S1 in FIG. 6 to step S2, that is, the switch process in FIG. Then, in step S10, it is determined that the value of the mode register M is 0, indicating that the basic timepiece mode is set, and in step S15 through step S11, it is determined that the switch S1 is operated, and the next step S16. In step S17, it is determined that the value of the measurement flag A is 0, and the value of the measurement flag A is set to 1, and the measurement is stored. After that, in step S18, an azimuth measurement process described in detail later, that is, the above-described detection outputs V1 to V4 are obtained, and a process for obtaining the azimuth, that is, the traveling direction indicated by the upper end of the display unit DS is executed based on these. In the following traveling direction calculation processing in step S19, the traveling direction obtained as described above is displayed in 16 directions (that is, north, north northeast, northeast, east northeast, east, southeast east, southeast, ... north northwest). Which of the two is closest, and find the closest azimuth. Then, in the subsequent display process (step S3 of FIG. 6, that is, FIG. 10), it is determined in step S130 that the value of the mode register M is 0, and step S13
The current time and date are displayed in the same manner as 1 in 1 above, and it is determined in step S132 that the value of the measurement flag A is 1 instead of 0, and the process proceeds to step S135. Step S
In 135, the traveling direction obtained in step S19 of FIG. 7 as described above is displayed on the dot display section DS3, and in the next step S136, the magnetic north, east, south, and west directions are displayed on the circular display section DS4. , In this case, only the direction of magnetic north is
Three rectangular display bodies at positions corresponding to the azimuth of the circular display section DS4 are displayed by lighting, and each other azimuth has one rectangular display body at a position corresponding to each azimuth of the circular display section DS4. , Is displayed by lighting. Then, in step S137, it is determined that a certain period of time has not elapsed since the start of the display, and the display process ends. After that, unless the switch is operated, the display processing is repeated until the above-mentioned certain time has elapsed (step S
1, S130 to S132, S135 to S137, S
1) The above display continues. For example, when the traveling direction at that time is northwest, the display on the display unit DS is as shown in b of FIG. The user rotates the rotary bezel rotatably mounted around the display unit DS, and the magnetic north, east, south, and west marked on the bezel are displayed in the circular display unit as described above. Magnetic north displayed on DS4,
By aligning with the east, south, and west, the thinner azimuth can be known from the marking of the thin azimuth on the bezel (see b in FIG. 13 above).

Further, when the display of the traveling direction and the like continues, and when a fixed time has elapsed, the display is made to the step S137.
In step S130 to S134, the value of the measurement flag A is reset to 0, and thereafter, the processes of steps S130 to S134 are repeated. That is, after the elapse of the certain period of time, the display state before the switch S1 is operated is automatically returned (see FIG. 13).

(B) Operation in azimuth measurement process The azimuth measurement process (that is, the process of FIG. 8) executed in step S18 of the switch process (FIG. 7) will be described in detail. In this azimuth measurement process, 1 is set in the detection circuit register I in step S70 of FIG. 8, and the CPU 11 sets the waveform synthesis circuit 10 in FIG.
The signal ST1 shown in is transmitted. Then, after this, the display section DS displays that measurement is in progress, and the waveform synthesis circuit 1
Waiting for the interrupt signal INT from 0 (step S7)
2, S73). For example, now, this signal ST1 as shown in Figure 11 to that sent to the waveform synthesizing circuit 10 to the timing t _1. At this time, as shown in FIG.
Is at the H level, the transfer gate 43 of the coil drive circuit 9 shown in FIG. 4 is in the ON state, and the capacitor 53 shown in FIG. 4 is applied with the voltage of the difference between the voltages Vcc and Vee and is charged. Also, the waveform synthesis circuit 1
In response to the signal ST1, 0 sets the signal Pc to the coil drive circuit 9 to the L level and the signal Pf to the amplifier circuit 5 to the H level at the timing t ₂ . Therefore, in the coil drive circuit 9 (see FIG. 4), the transfer gates 40 and 43 which are turned on / off by the signal Pc are turned off, and in the amplifier circuit 5 (see FIG. 3) are turned on / off by the signal Pf. Transfer gate 2
1 is turned on, and the capacitor 23 is connected to the magnetic sensor 1
The pads Pd2 and Pd4 are charged to a voltage obtained by amplifying the potential difference PS1-PS2. Next, timing t ₃
11, the signals P1 and N2 sent from the waveform synthesizing circuit 10 to the coil driving circuit 9 become H level, the transfer gate 44 and the NPN transistor 58 of the coil driving circuit 9 are turned on, and the transfer gate is turned on. Since 44 is turned on, the PNP transistor 54 is also turned on. Since the PNP transistor 54 and the NPN transistor 58 are turned on, the capacitor 53, the PNP transistor 54, and the terminal W
1, coil CL1, terminal W2, NPN transistor 5
8. A circuit called a capacitor 53 is formed, and a large current instantaneously flows from the capacitor 53 charged as described above to the coil CL1. Due to this large current, a large magnetic field is applied to the magnetoresistive elements MR1 to MR4 of the magnetic sensor 1, and their magnetizations are aligned in the direction of the magnetic field, so that the magnetic field can be stably measured.

After the above operation, the waveform synthesizing circuit 10
At the timing t _4, as shown in FIG. 11, a signal Pp to L level, the signal N4 to H level. Therefore, the voltage difference between the voltage Vcc and the voltage Vee 'is applied to the coil CL1 connected between the terminals W1 and W2 of the coil drive circuit 9, and the transfer gate 42 is turned off to transfer the transfer gate 41. Is turned on, the base current of the PNP transistor 54 is controlled by the operational amplifier 39 so that the current flowing through the resistor 47 becomes constant. Therefore, the current flowing through the coil CL1 becomes constant, and a constant bias magnetic field is applied to the magnetoresistive elements MR1 to MR4. Even at this point in time, in the amplifier circuit 5, the capacitor 23 is charged with the voltage obtained by amplifying the potential difference PS1-PS2.
The capacitor 23 is charged with a voltage according to the magnetic field obtained by combining the bias magnetic field and the geomagnetic field.

Next, as shown in FIG. 11, at the timing Ta when the above state is maintained, the signal Pf is set to L first.
It becomes a level. Therefore, the transfer gate 21 of the amplifier circuit 5 is turned off, and the capacitor 23 holds the voltage corresponding to the composite magnetic field. After that,
The signals Pc, Pp, P1, N2 and N4 respectively return to the states before the timing t ₂ .

After the measurement in the state where the downward bias magnetic field is applied to the magnetic sensor 1 by the coil CL1 is completed as described above, the timing t is set as shown in FIG.
After ₅ , each signal from the waveform synthesizing circuit 10 changes from H level to L level or from L level to H level, and the amplifier circuit 5 and the coil drive circuit 9 perform the same or similar operation as described above. The PNP transistor 55 and the NPN transistor 57 are turned on, and a current flows in the coil CL1 in the opposite direction to the above case (that is, the bias magnetic field applied to the magnetic sensor 1 is opposite to the above case, and And the capacitor 24 of the amplifier circuit 5 at the timing Tb.
In addition, a voltage opposite to the voltage of the previous capacitor 23 is held (note that the output voltage is smaller than the offset voltage when a magnetoresistive element is used because of such a configuration). This is because of consideration.)

After reaching the above state, as shown in FIG. 11, the waveform synthesizing circuit 10 causes the CPU 11 to operate at timing t _8.
An interrupt signal INT is sent to (see FIG. 2). CPU1
1 detects this interrupt signal INT in step S72 of FIG. 8, sends the signal ST2 to the waveform synthesizing circuit 10 at timing t _{9 as} shown in FIG. 11 in step S74, and again waits for the interrupt signal INT in the same manner as above. (Steps S57 and S76). On the other hand, the waveform synthesis circuit 10 receives the signal ST2 and sends the conversion timing signal Sa to the A / D conversion circuit 6. Upon receiving this conversion timing signal Sa, A
The / D conversion circuit 6 includes the capacitor 23 of the amplifier circuit 5,
The voltage VS obtained by amplifying the voltage difference of 24 is fetched from the output terminal of the operational amplifier 20 of the amplifier circuit 5, converted into a digital value and transmitted as a detection output V1, which is stored in the register 7. During this digital conversion operation, the A / D conversion circuit 6
Sends the in-conversion signal Sb to the waveform synthesizing circuit 10. However, when the digital converting operation is finished and the in-conversion signal Sb is stopped, the waveform synthesizing circuit 10 detects it and outputs the timing as shown in FIG. At t ₁₀ , to the CPU 11 again,
Send the interrupt signal INT. The CPU 11 detects the interrupt signal INT in step S75 of FIG. 8, detects that the value of the detection count register I is 1 in step S77, proceeds to step S78, reads the detection output V1 from the register 7, and reads the RAM 13 from the RAM 13. Stored in the memory V1 in step S82, the value of the detection count register I is incremented by 1 in the next step S82, and the process returns to step S71.

Further, in the step S71, transmits a signal ST1 at the timing t ₁₁ as shown in FIG. 11, it is thereafter, the same operation as described above will be performed (step S72~S77). However, the waveform synthesis circuit 1
0, the coil drive circuit 9, and the amplifier circuit 5 side are operated slightly differently from the above case, and at timing Tc in FIG. 11, the PNP of the coil drive circuit 9 is reached.
The transistor 55 and the NPN transistor 57 are turned on, and a current flows from the terminal W2 side to the terminal W1 in the coil CL1.
The bias magnetic field is directed upward from the magnetic sensor 1, and the output of the magnetic sensor 1 in that case, that is, the voltage obtained by amplifying the potential difference PS1-PS2 is held in the capacitor 23 of the amplifier circuit 5. Further, at the timing Td shown in FIG. 11, the PNP transistor 54 and the NPN transistor 58 of the coil drive circuit 9 are turned on, and the coil CL1 flows from the terminal W1 side to the terminal W2 contrary to the above case. Is directed downward from the magnetic sensor 1, and the output of the magnetic sensor 1 in that case, that is, the voltage obtained by amplifying the potential difference PS1-PS2 is held in the capacitor 24 of the amplifier circuit 5. And capacitors 23 and 24
The detection output V2 obtained by digitizing the voltage VS obtained by amplifying the potential difference of is stored in the register 7.

After detecting the interrupt signal INT at the timing T ₂₀ shown in FIG. 11 in step S75 of FIG. 8, the process proceeds to step S79 via step S77,
The detection output V2 stored in the register 7 is stored in the RAM 13
Stored in the memory V2 in step S82, the value of the detection count register I is set to 3 in step S82, and the process returns to step S71.

Further, a signal ST1 was sent at time t ₂₁ as shown in FIG. 11 in the step S71, the subsequent, similar operation as described above will be performed (step S72~S77). However, on the side of the waveform synthesizing circuit 10, the coil driving circuit 9, and the amplifying circuit 5, a slightly different operation is performed, and a current is first supplied to the coil CL2 connected between the terminals W2 and W3 of the coil driving circuit 9. Apply a leftward bias magnetic field to the magnetic sensor 1 flowing from the W3 side,
Next, a rightward bias magnetic field is applied to the magnetic sensor 1 flowing from the terminal W2 side, the voltage obtained by amplifying the output of the magnetic sensor 1 in each case is held in the capacitors 23 and 24, and the voltage VS obtained by amplifying the difference between these voltages is applied. Is digitized to obtain a detection output V3, which is stored in the register 7. Then, the CPU 11 outputs the subsequent interrupt signal INT in step S7.
5, the detected output V3 is stored in the memory V3 of the RAM 13 in step S80 through step S77, and the value of the detection count register I is incremented by 4 in step S82 to return to step S71.

Further, a signal ST1 was sent at time t ₃₁ as shown in FIG. 11 in the step S71, thereafter the above case and similar operations will be performed (step S
72-S77). However, in this case, the timing t
The sequence of operations after ₂₁ and the order of generation of the bias magnetic field by the coil CL2 are opposite. First, a bias magnetic field of the magnetic sensor 1 to the right and then to the left is generated, and a voltage obtained by amplifying the output of the magnetic sensor 1 in each case is generated. Capacitors 23 and 24
The voltage VS obtained by amplifying the voltage difference is digitized to obtain the detection output V4, which is stored in the register 7. Then, the CPU 11 causes the subsequent interrupt signal INT
In step S75, and in step S81 after step S77, the detection output V4 is stored in the memory V of the RAM 13 in step S81.
4, and the process proceeds to step S85 and subsequent steps.

In step S85, the detection output V2 stored in the memory V2 is subtracted from the detection output V1 stored in the memory V1 of the RAM 13, and the difference, that is, the data Y is stored in the memory Y of the RAM 13, Step S8
In 6, the detection output V4 stored in the memory V4 is subtracted from the detection output V3 stored in the memory V3, and the difference, that is, the data X is stored in the memory X of the RAM 13. Then, the value obtained by subtracting the correction value of the Y component memory HY from the data Y is divided by the value obtained by subtracting the correction value of the X component memory HX from the data X to obtain the arctangent (main value) of the quotient. , This is stored in the azimuth data memory D.

Next, in the processes of steps S88 to S91, the actual azimuth is obtained from the azimuth data of the azimuth data memory D obtained as described above, that is, the principal value of the arctangent. That is, in step S88, it is determined whether the data X is negative. If the data X is not negative, the direction of the direction data memory D is increased by 180 ° in step S89. If the data X is not negative, the data Y is negative in step S90. Judge,
If negative, the azimuth of the azimuth data memory D is increased by 180 ° in step S91. When the processing of steps S89 and S91 is completed, and
When it is determined in 90 that the data Y is not negative, the process proceeds to step S92.

In step S92, it is checked whether the correction value stored in the north correction value memory HK is a value other than 0. If it is a value other than 0, in step S93 the direction data in the direction data memory D is checked. To north correction value memory HK
The difference obtained by subtracting the correction value of is stored in the corrected azimuth data memory F, but when it is determined in step S92 that the correction value of the north correction value memory HK is 0, step S94
The azimuth data in the azimuth data memory D is stored in the azimuth data memory F after correction as it is.

(C) Operation in normal state of navigation mode As shown in FIG. 13, the switch S3 is operated to switch from the basic timepiece mode to the navigation mode.
At this time, the operation is detected in step S11 of FIG. 7, the value of the mode register M is set to 1 in the navigation mode in step S12, and the value of the azimuth correction flag L is set to 0 to set the normal state. In step S13, the memory designation register N is set. The value of is set to 0, and the measurement result is not stored,
In the next step S14, the value of the measurement flag B is set to 0,
It is memorized that the direction measurement has not been instructed yet.

In the subsequent display processing (FIG. 10), step S
After 130, in step S140, the navigation display NA of the display unit DS is lit and displayed, and it is determined that the value of the azimuth correction flag L is 0. Further, in step S142, the value of the memory designation register N is 0. It is determined that the current time is displayed on the main display section DS1 and the date is displayed on the sub display section DS2 in step S143. Next, in step S144, the value of the measurement flag B is not 1, and it is determined that the measurement in the traveling direction has not been performed yet, and the display processing ends. However, the display of the display section DS in this case is, for example,
As shown in FIG. 13c.

After the navigation mode is set as described above, the measured traveling direction and the like are stored in the navigation memory M.
When there is no intention to store in E1 to ME5 and the user simply wants to measure and confirm the traveling direction at that time, the switch S1 is operated. At this time, the operation is detected in step S25 of FIG. 7, and it is confirmed that the value of the memory designation register N is 0. In the next step S27, the value of the measurement flag B is 0 and the navigation mode is set. Then, it is confirmed that the measurement is not yet performed, and in step S28, the value of the measurement flag B is set to 1 and the fact that the measurement is performed is stored, and the process proceeds to the next step S29. In this step S29, the azimuth measurement process described in detail above (FIG. 8) is performed, and the azimuth pointed by the upper end of the display unit DS at that time in the corrected azimuth data memory F, that is, the traveling azimuth at that time ( The angle to the north) is stored. Then, in step S30, it is checked which of the 16 displayable directions the traveling direction stored in the corrected azimuth data memory F is, and the closest direction is obtained.

In the subsequent display process (FIG. 10), after the processes of steps S130 and S140 to S143 are executed in the same manner as described above, the value of the measurement flag B is 1 in step S144, that is, the measurement is performed. In step S145, the dot display section DS3 displays the traveling direction obtained in step S30, and then in step S1.
At 46, the magnetic north, east, south, and west directions are displayed on the circular display portion DS4 in the same manner as described above.

To switch from the above state to the state in which the measured traveling direction is stored, as shown in FIG.
Operate 4. At this time, the operation is performed in step S40 of FIG.
In step S41, the memory designation register N is detected.
The value of is increased by 1 and the navigation memory ME
1 is designated, it is determined in step S42 that the value of the memory designation register N does not exceed 5, and the process proceeds to the subsequent display process. In the display process, after the same process as described above (steps S130, S140, S141), it is determined in step S142 that the value of the memory designation register N is not 0, and the process proceeds to step S147 and subsequent steps. Then, in step S147, the memo display ME of the display section DS is lit and displayed, and in step S148, the time already stored in the navigation memory designated by the value (1 in this case) of the memory designation register N, that is, the navigation memory ME1. The date (time / date of the last measurement) is displayed on the main display section DS1 and the sub display section DS2, and in the next step S149, the traveling direction stored in the navigation memory ME1 is displayed on the dot display section DS3. In step S150, each direction (that is, magnetic north, east, south, and west) stored in the navigation memory ME1 is displayed by using the rectangular display body of the circular display section DS4, and in the next step S151, the memory designation register is displayed. The value of N is displayed at the right end of the main display section DS1.

In the above-mentioned state, the traveling direction and the like at that time are newly measured, and the result is measured in the navigation memory ME1.
In order to memorize in the above, the switch S1 is operated with the upper end of the display section DS facing the traveling direction. At this time, the operation is detected in step S25 of FIG. 7, it is determined in step S26 that the value of the memory designation register N is not 0, and the process proceeds to step S35. In step S35, the azimuth measurement process described in detail above is executed, and the corrected azimuth data memory F stores the traveling direction (angle to north) at that time. In the following step S36, similarly to the processing in the step S30, it is checked which of the 16 displayable directions the traveling direction of the corrected azimuth data memory F is closest to, and the closest direction is obtained. Then, in step S37, the date / time, magnetic north, and traveling direction relating to the current direction measurement are stored in the navigation memory ME1. In the subsequent display processing, steps S130, S140, S141 and S1 are performed in the same manner as described above.
The process of 47 is executed, and the process of steps S148 to S151 is also similar to the above-mentioned process. However, unlike the above-described case, the measurement is performed this time, and the navigation memory ME is executed.
The traveling direction and the like newly stored in 1 are displayed on the display unit DS. For example, the day is June 30, and the current time is 9:30.
Minutes, the current direction of travel is south-southwest, and when these are stored in the navigation memory ME1, the display unit DS
Is displayed as shown in d of FIG.

Thereafter, each time the switch S4 is operated, it is detected in step S40 of FIG. 7 and the value of the memory designating register N is increased by 1 (steps S41, S42) in the same manner as described above, and the display is performed. In the processing, the past measurement data stored in the navigation memory designated by the value of the memory designation register N is displayed on the display unit D in the same manner as described above.
It is displayed on S (steps S130, S140, S1
47-S151). Then, in order to store the current traveling direction and the like in the navigation memory designated by the memory designation register N, the switch S1 is operated with the upper end of the display unit DS facing the traveling direction. Also at this time, the operation is detected in step S25 of FIG.
In Steps S35 to S37 after 6, the traveling direction and the like at that time are measured, and the measurement result and the like are stored in the navigation memory designated by the memory designation register N. Then, in the display process, the traveling direction at that time, which is newly stored in the navigation memory, is displayed on the display section DS.

As described above, the switch S4 is operated to successively increase the value of the memory designation register N by 1, so that the value of the memory designation register N becomes 5 and the navigation memory ME5 is designated. When the switch S4 is further operated in the state, in step S40 of FIG.
The operation is detected, the value of the memory designation register N is increased by 1 by 6 in step S41, and it is determined in step S42 that the value of the memory designation register N exceeds 5, and the process proceeds to step S43 and subsequent steps. . In step S43, the value of the memory designation register N is returned to 0, and in the next step S44, the newest measurement data stored in the navigation memories ME1 to ME5 is navigated.
The measurement data is rearranged and stored in the navigation memory ME1 such that the next new one is stored in the navigation memory ME2, and the value of the measurement flag B is reset to 0 in the next step S45. In the display process, step S13
0, S140 to S144 are performed in the same manner as described above (that is, the traveling direction and the like are not displayed), and the display is returned to that shown in C of FIG.

(D) Operation in the azimuth correction state of the navigation mode For example, now, in the normal state of the navigation mode, the display section DS is in the display state as shown in FIG. I shall. To switch from this state to the azimuth correction state, the switch S2 is operated as shown in FIG. At this time, in response to the operation, step S40 in FIG.
In step S50, the value of the azimuth correction flag L is set to 1 to set the azimuth correction state, the value of the correction value calculation method register G is set to 0 in step S51, and the two-point correction is designated. The correction register J is set to 1 to instruct measurement of the azimuth at the first point. In the display process, steps S130 and S14
After 0, S141, it is determined in step S155 that the value of the correction value calculation method register G is 0 and the two-point correction is instructed, and the process proceeds to step S156 where the value of the two-point correction register J is 1, Judging that it is a point measurement,
In step S157, the number 1 is displayed on the dot display section DS3, and at the same time, the upper three of the rectangular display bodies of the circular display section DS45 are blinked and the lower three are lit.

After reaching the above state, the upper end of the display section DS is oriented in an arbitrary direction, and the switch S1 is operated on it (see FIG. 14). In response to this, step S1 in FIG.
After 0, S20, S55, and S60, the process proceeds to step S67, that is, the azimuth correction switch process of FIG. Then, in step S100, it is determined that the value of the correction value calculation method register G is 0, and the two-point correction is instructed.
In 01, it is determined that the value of the two-point correction register J is 1 and the measurement is the first point, and in step S102, the switch S1
Is confirmed to be operated, and in step S103, the azimuth measuring process described in detail above is executed. Then step S1
At 04, the data Y obtained by the azimuth measurement process is stored in the first point Y component memory HY1, and at step S105, the data X obtained by the azimuth measurement process is stored in the first point X component memory HX1. . Next, in step S106, 2 is set in the two-point correction register J to instruct measurement of the second point, and in step S107, the dot display section DS
Instruct 3 to display OK characters for 1 second only.
As a result, the display on the display unit DS is displayed for 1 second only.
It becomes something like d.

After the above state is completed, the process proceeds to steps S130, S140, S141 and S155 of the display process, and it is determined in step S156 that the value of the two-point correction register J is already 1 instead of 2. And step S
Proceeding to 158, the number 2 is displayed on the dot display section DS3. However, the display on the display section DS is as shown in FIG. The user is 180 ° from the previous bearing in this state.
By pointing the shifted opposite direction at the upper end of the display section DS, the switch S1 is operated again as shown in FIG. In this case, similarly to the above, step S1 of FIG.
After 00, the process proceeds to step S101, it is determined that the value of the two-point correction register J is not 1, the step S110 determines that the operated switch is the switch S1, and the process proceeds to step S11. Then, in step S111, the azimuth measurement process described in detail above is executed, in step S112 the measured data Y is stored in the second point Y component memory HY2, and in step S113, the measured data X is changed to the second point X. Stored in the component memory HX2. Continued Step S11
In 4, the arithmetic mean of the data in the first point Y component memory HY1 and the data in the second point Y component memory HY2 is obtained and stored in the Y component memory HY. In step S115, the first point X component memory The arithmetic mean of the data of the memory HX1 and the data of the second point X component memory HX2 is obtained and stored in the X component memory HX.

The data stored in the Y component memory HY and the X component memory HX will be described. When the magnetic sensor 1 has no offset at all, the data X and Y obtained by the azimuth measurement process change sinusoidally according to the measurement azimuth (angle) as shown in FIG. But,
In reality, since the magnetic sensor 1 has an offset, the data X and Y are as shown in FIG. As is clear from the figure, the offset amount is the arithmetic mean of the measurement data in the azimuth shifted by 180 °. Therefore, in the processing of steps S114 and S115, offset amounts in the Y direction (vertical direction of the magnetic sensor 1) and the X direction (horizontal direction of the magnetic sensor 1) are obtained and stored in the Y component memory HY and the X component memory HX. It is a process to do.

After the processing of step S115 is completed, the north correction value memory HK is cleared in step S116, and in step S117, it is instructed to display the character "OK" on the dot display section DS3 for only one second.
At 118, the value of the azimuth correction flag L is returned to 0, and the normal state is set. As a result, the display on the display unit DS becomes as shown in g of FIG. 14 for only one second, and then returns to that of (a) in FIG. It should be noted that the above two-point correction processing causes Y
The data (correction value) stored in the component memory HY and the X component memory HX will be used for correction of the measurement data in step S87 of FIG. 8 from the next azimuth measurement process.

Next, the north direction correction will be described. This north direction correction state is entered by operating the switch S3 in the above two-point correction state as shown in FIG. That is, before performing the second measurement in the two-point correction (when the second measurement is performed, the value of the azimuth correction flag L becomes 0 in step S118 of FIG. 9 and the normal state is returned).
The switch S3 is operated. At this time, the operation is detected in step S60 of FIG. 7, it is determined in step S61 that the value of the correction value calculation method register G is 0, and the value of the correction value calculation method register G is set to 1 in the next step S62. The north direction is corrected. In the subsequent display process, steps S130, S140, and S141 are performed before step S1.
At 55, it is determined that the value of the correction value calculation method register G is 1 instead of 0, and the process proceeds to step S159 to display the letter N on the dot display section DS3 of the display section DS (see h in FIG. 14). .

In the above state, the user confirms the correct direction of magnetic north using a magnetic needle or the like, directs the upper end of the display section DS of this electronic compass to that direction, and operates the switch S1 on it. To do. At this time, the operation is detected in step S120 of FIG. 9, the process proceeds to step S121, the azimuth measurement process described in detail above is executed, and in the subsequent step S121, the azimuth measurement process is performed and the azimuth data memory D is stored. The azimuth data is stored in the north correction value memory HK. Then, in step S123, the character “OK” is displayed on the dot display section DS3 for only one second (see j in FIG. 14), and in step S124, the value of the azimuth correction flag L is set to 0.
Then, the navigation mode is returned to the normal state. In the subsequent display processing, steps S130 and S14
0, S141 to S144 are performed, and the display on the display unit DS is as shown in FIG. 14A, that is, in FIG. 13C.

It should be noted that, in the above north azimuth correction state, before operating the switch S1 to execute the measurement, the switch S1 is operated.
3 is operated, it is detected in step S60 of FIG. 7, it is determined that the value of the correction value calculation method register G is not 0 in step S61, and the correction value calculation method register G of the correction value calculation method register G is determined in step S65. The value is set to 0 and the above-described two-point correction is instructed, and in the next step S66, the two-point correction register J is set to 1
Is stored and the fact that it is the first point is stored (see FIG. 14).

To switch from the navigation mode to the basic timepiece mode, the switch S3 is operated in the normal state of the navigation mode as shown in FIG. At this time, the operation is detected in step S21 of FIG. 7, and in step S22, the value of the mode register M is set to 0 to set the basic clock mode, and the value of the measurement flag A is set to 0 to store that the measurement is not yet performed. Then, in the display processing, the processing of steps S130 to S134 is performed,
The display on the display unit DS is as shown in FIG.

[0055]

As described above in detail, according to the present invention,
(EN) It is possible to provide an electronic azimuth meter that can correct an error in a detection output due to magnetization of the device itself by an easy operation.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a magnetic sensor used in an electronic compass according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an electronic compass according to an embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of an amplifier circuit in FIG.

4 is a diagram showing a configuration of a coil drive circuit in FIG.

5 is a diagram showing a configuration of a RAM in FIG.

FIG. 6 is a general flowchart showing an outline of the operation of the above embodiment.

FIG. 7 is a flow chart showing the switch processing in FIG. 6 in detail.

FIG. 8 is a flowchart showing in detail the azimuth measuring process in FIG.

FIG. 9 is a flowchart showing in detail the azimuth correction switch processing in FIG.

FIG. 10 is a flowchart showing in detail the display processing in FIG.

FIG. 11 is a diagram for explaining azimuth measurement processing.

FIG. 12 is a diagram for explaining azimuth measurement processing.

FIG. 13 is a diagram showing a change in display accompanying a switch operation.

FIG. 14 is a diagram showing a transition of display in the two-point correction and north correction states.

[Explanation of symbols]

 1 magnetic sensor 1a substrate MR1 to MR4 magnetoresistive element CL1, CL2 coil DS display section DS1 main display section DS2 sub display section DS3 dot display section DS4 circular display section Sa conversion timing signal Sb in-conversion signal INT interrupt signal DP circular display panel J 2-point correction flag I Detection count register D Direction data memory F Corrected direction data memory HK North correction value memory ME1 to ME5 Navigation memory

Claims (2)

[Claims] 1. A component in the first direction of geomagnetism and the first component
Geomagnetic detection means for outputting first and second output signals according to the strength of the component in the second direction orthogonal to the direction, and the first geomagnetic detection means for outputting in the predetermined direction, The output signal of 2 and the predetermined direction are 180
° Correction value calculation means for obtaining a correction value from the first and second output signals output by the geomagnetism detection means when facing in the opposite direction, and the geomagnetism detection after the correction value is obtained by the correction value calculation means An azimuth calculating means for correcting the first and second output signals detected by the means to obtain the azimuth from the corrected signals. 2. A component in the first direction of the geomagnetism and the first component
Geomagnetic detection means for outputting the first and second output signals according to the intensity of the component in the second direction orthogonal to the direction, the external operation switch, and the geomagnetic detection when the external operation switch is operated. Correction from the first and second output signals output from the means and the first and second output signals output from the geomagnetic detection means when the external operation switch is directed in a direction different from the direction in which the external operation switch is operated. A correction value calculating means for obtaining a value, and the first and second output signals detected by the geomagnetism detecting means after the correction value is obtained by the correction value calculating means are corrected, and the azimuth is obtained from the corrected signal. An electronic azimuth meter comprising: azimuth calculation means.