JP2006098309A - Magnetic measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic measuring apparatus shortening a time required for magnetic measurements. <P>SOLUTION: Measurements are started by measurements start commands 101 and 102 indicating start of magnetic measurements. The measurement command 101 starts X-axis measurements 103, and the measurement command 102 starts Z-axis measurements 104. Y-axis measurements 105 are continuously stared when the X-axis measurements 103 are completed. When measurements of magnetism in the directions of a Y-axis and a Z-axis are completed, measurements results are outputted by output commands 106 and 107. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a magnetic measurement circuit including a triaxial magnetic sensor that measures magnetism in three axial directions, and more particularly to a magnetic measurement circuit that shortens the time required for magnetic measurement.

As an application example of a magnetic measurement circuit including a magnetic sensor that measures magnetism (geomagnetism), a portable terminal such as a mobile phone that performs azimuth measurement based on the geomagnetism measured by the magnetic measurement circuit is known. The measured orientation is used for display of a map, for example. As an example, a mobile terminal that has a GPS (Global Positioning System) that performs position measurement and has a function of displaying a map based on the current position in accordance with the orientation (direction) of the mobile terminal has appeared. Patent Document 1 describes an integral magnetometer that measures the integral value of the amount of magnetic flux in three axial directions. Patent Document 2 describes a magnetic sensor using a magnetoresistive effect element (GMR).
JP-A-4-93782 JP 2003-202365 A

  In the conventional magnetic measurement circuit, all magnetisms in the three axis directions are measured with one command, and the result is output. For example, when a magnetic measurement start command is generated, the X-axis magnetic sensor measures the magnetism in the X-axis direction, the Y-axis magnetic sensor then measures the magnetism in the Y-axis direction, and then continues in the Z-axis direction. This magnetic sensor measures the magnetism in the Z-axis direction, and finally all measurement results are output. However, when magnetism is measured by the above method, there are problems that the measurement time is increased and the circuit scale is increased. In addition, even when it is necessary to measure only two axes, there is also a problem that the measurement time is increased correspondingly because measurements are performed collectively for the three axes.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a magnetic measurement circuit capable of shortening the time required for magnetic measurement.

  The present invention has been made to solve the above-described problems. The invention according to claim 1 is directed to a magnetism measuring means for measuring magnetism in three axial directions and magnetism in two axial directions among the three axial directions. And a control means for controlling the magnetism measuring means so as to measure the magnetism in the remaining one axis direction in parallel with the measurement of the magnetism in the two axis directions. It is a measurement circuit.

  According to a second aspect of the present invention, in the magnetic measurement circuit according to the first aspect, the magnetic measurement means includes a first magnetic sensor and a second magnetic sensor that measure magnetism in each of the three axial directions. And a third magnetic sensor, wherein the control means measures the first magnetic sensor and the second magnetic sensor so that the first magnetic sensor and the second magnetic sensor measure magnetism in parallel. The third magnetic sensor is controlled so that the third magnetic sensor measures the magnetism continuously after the measurement of magnetism by the first magnetic sensor is completed.

  According to a third aspect of the present invention, in the magnetic measurement circuit according to the first aspect, the first magnetic sensor unit including the first magnetic sensor and the third magnetic sensor, and the second magnetic sensor. A first control unit that instructs the first magnetic sensor unit and the second magnetic sensor unit to start magnetic measurement in parallel, and The first magnetic sensor unit includes a second control unit that starts measurement of magnetism by the third magnetic sensor after the measurement of magnetism by the first magnetic sensor is completed. .

  According to the present invention, the magnetism in the biaxial direction among the three axis directions is continuously measured, and the magnetism in the remaining one axis direction is measured in parallel with the measurement of the magnetism in the other two axis directions. Therefore, the effect that the time required for magnetic measurement can be shortened can be obtained.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a magnetic measurement circuit according to an embodiment of the present invention. The magnetic measurement circuit according to the present embodiment is mounted on a portable terminal such as a cellular phone or a PDA (Personal Digital Assistance). This magnetic measurement circuit includes a CPU 1, a magnetic sensor unit 2, and a magnetic sensor unit 3.

  The CPU 1 controls the entire magnetic measurement circuit and controls each part in the portable terminal by inputting / outputting a control signal or the like via the bus B. Regarding the magnetic measurement, the CPU 1 controls the measurement of magnetism by the magnetic sensor unit 2 and the magnetic sensor unit 3 with respect to the magnetic sensor unit 2 and the magnetic sensor unit 3 via the interface 27 (37). The magnetic sensor unit 2 and the magnetic sensor unit 3 are each configured as one chip (1 IC chip).

  The magnetic sensor unit 2 measures magnetism in the X-axis and Y-axis directions. The magnetic sensor unit 2 is provided with an SCL terminal 20a to which a clock signal for data signal synchronization is input from the CPU 1, and an SDA terminal 20b for inputting / outputting data signals to / from the CPU 1. Similarly, the magnetic sensor unit 3 is provided with an SCL terminal 30a to which a clock signal for data signal synchronization is input from the CPU 1 and an SDA terminal 30b for inputting / outputting data signals to / from the CPU 1.

  In the magnetic sensor unit 2, the X-axis magnetic sensor 21 measures the magnetism in the X-axis direction and outputs a signal indicating the measurement result. The Y-axis magnetic sensor 22 measures the magnetism in the Y-axis direction and outputs a signal indicating the measurement result. Since the switch 23 takes out a signal from one of the X-axis magnetic sensor 21 and the Y-axis magnetic sensor 22, the X-axis magnetic sensor 21 and the amplification circuit 24 are connected, or the Y-axis magnetic sensor 22 and the amplification circuit 24 are connected. Switch the connection so that is connected. The amplifying circuit 24 amplifies the signal indicating the magnetic measurement result output from the X-axis magnetic sensor 21 and the Y-axis magnetic sensor 22 and outputs the amplified signal to the A / D 25.

  The A / D 25 performs operations such as generation of a reference voltage in order to convert the analog signal input from the amplifier circuit 24 into a digital signal. The control circuit 26 counts the voltage value in synchronization with the change in the reference voltage generated by the A / D 25, controls the counter for generating digital data indicating the voltage value, and each circuit related to A / D conversion. It has a circuit to do. While changing the reference voltage, the A / D 25 compares the voltage with the voltage of the signal input from the amplifier circuit 24, and outputs a signal indicating the comparison result to the control circuit 26. The control circuit 26 changes the value of the counter in response to the change of the reference voltage value by the A / D 25. When the signal output from the A / D 25 indicates that the reference voltage has reached the voltage to be compared, the control circuit 26 sets the current counter value to the interface 27 and the SDA terminal 20b. To CPU1.

  In the magnetic sensor unit 3, the Z-axis magnetic sensor 31 measures the magnetism in the Z-axis direction and outputs a signal indicating the measurement result. The tilt sensor 32 measures the tilt of the mobile terminal with respect to the vertical direction and outputs a signal indicating the measurement result. The amplification circuit 33 amplifies the signal indicating the measurement result output from the Z-axis magnetic sensor 31 and outputs the amplified signal to the switch 34. The switch 34 is connected so that the amplification circuit 33 and the A / D 35 are connected or the inclination sensor 32 and the A / D 35 are connected in order to extract a signal from one of the amplification circuit 33 and the inclination sensor 32. Switch.

  The A / D 35 performs operations such as generation of a reference voltage in order to convert the analog signal input from the amplifier circuit 33 into a digital signal. The control circuit 36 counts the voltage value in synchronization with the change in the reference voltage generated by the A / D 35, controls the counter that generates digital data indicating the voltage value, and each circuit related to the A / D conversion. A control circuit is provided. While changing the reference voltage, the A / D 35 compares the voltage with the voltage of the signal input from the amplifier circuit 33, and outputs a signal indicating the comparison result to the control circuit 36. The control circuit 36 changes the value of the counter in response to the change of the reference voltage value by the A / D 35. When the signal output from the A / D 35 indicates that the reference voltage has reached the voltage to be compared, the control circuit 36 sends the value of the counter at that time to the interface 37 and the SDA terminal 30b. To CPU1.

  FIG. 2 is a block diagram showing a functional configuration related to magnetic measurement of the magnetic measurement circuit according to the present embodiment. Hereinafter, each component in the figure will be described. The control unit 11 has a configuration corresponding to the CPU 1. The external I / Fs 12 and 17 have configurations corresponding to the interfaces 27 and 37, respectively. The X / Y switching control unit 13 is a configuration included in the control circuit 26 and switches magnetic measurement in the X-axis and Y-axis directions. The magnetic sensor X14 has a configuration corresponding to the X-axis magnetic sensor 21, and measures magnetism in the X-axis direction. The magnetic sensor Y15 has a configuration corresponding to the Y-axis magnetic sensor 22, and measures magnetism in the Y-axis direction. The ADC 16 has a configuration corresponding to the A / D 25 and the control circuit 26. The ADC 16 converts an analog signal indicating a measurement result of magnetism in each axial direction measured by the magnetic sensor X14 and the magnetic sensor Y15 into a digital signal, and converts the data into a digital signal. Temporary registers for temporary storage are provided for the X axis and the Y axis, respectively. The external I / F 12, the X / Y switching control unit 13, the magnetic sensor X14, the magnetic sensor Y15, and the ADC 16 constitute a magnetic sensor unit 2a corresponding to the magnetic sensor unit 2.

  The magnetic sensor Z18 has a configuration corresponding to the Z-axis magnetic sensor 31, and measures magnetism in the Z-axis direction. The ADC 19 has a configuration corresponding to the A / D 35 and the control circuit 36, converts an analog signal indicating a magnetic measurement result in the Z-axis direction measured by the magnetic sensor Z18 into a digital signal, and temporarily stores the data. It has a temporary register. The external I / F 17, the magnetic sensor Z 18, and the ADC 19 constitute a magnetic sensor unit 3 a corresponding to the magnetic sensor unit 3.

  Next, the operation of the magnetic measurement circuit according to the present embodiment will be described based on the operation of the configuration shown in FIG. FIG. 3 shows the command by the control unit 11 and the timing of the magnetic measurement in each axis direction. When starting the magnetic measurement, the control unit 11 outputs a measurement start command indicating the start of measurement to the magnetic sensor unit 2a, and subsequently outputs it to the magnetic sensor unit 3a (measurement commands 101 and 102 in FIG. 3).

  The measurement command input to the magnetic sensor unit 2a is input to the X / Y switching control unit 13 via the external I / F 12. The X / Y switching control unit 13 connects the magnetic sensor X14 to the ADC 16 based on the measurement command. The ADC 16 measures magnetism in the X-axis direction (X-axis measurement 103 in FIG. 3). The digital data of the measurement result is accumulated in a temporary register in the control unit of the ADC 16.

  On the other hand, the measurement command input to the magnetic sensor unit 3a is input to the magnetic sensor Z18 via the external I / F 17. Based on this measurement command, the ADC 19 starts measuring the magnetism in the Z-axis direction (Z-axis measurement 104 in FIG. 3). The digital data of the measurement result is accumulated in a temporary register in the control unit of the ADC 19. With the above operation, magnetic measurement in the Z-axis direction by the magnetic sensor Z18 is started almost simultaneously with the start of measurement of magnetic measurement in the X-axis direction by the magnetic sensor X14. Thereafter, magnetic measurement in the X-axis direction and magnetic measurement in the Z-axis direction are performed independently and in parallel by each ADC.

  When the measurement of the magnetism in the X-axis direction is finished, the control unit of the ADC 16 outputs a signal indicating the end of the measurement. With this signal, the control unit of the ADC 16 switches the X / Y switching control unit 13 to instruct the magnetic sensor Y15 to measure magnetism. Next, the ADC 16 starts measuring the magnetism in the Y-axis direction (Y-axis measurement 105 in FIG. 3). The measurement result is accumulated in a temporary register in the control unit of the ADC 16 in the same manner as the measurement result in the X-axis direction.

  When the measurement of magnetism in the Y-axis direction is completed, the control unit of the ADC 16 outputs a signal indicating the completion of measurement. This signal can be known by the control unit 11 via the external I / F 12. When the measurement of magnetism in the Z-axis direction is finished, the control unit of the ADC 19 outputs a signal indicating the end of measurement. This signal can be known by the control unit 11 via the external I / F 17. Based on this signal, the control unit 11 determines that the magnetic measurement in the Y-axis and Z-axis directions has been completed, and outputs an output command to the magnetic sensor unit 2a in order to acquire measurement data. Subsequently, the magnetic sensor unit 3a (output commands 106 and 107 in FIG. 3).

  The output command is input to the external I / F 12 of the magnetic sensor unit 2a and also input to the external I / F 17 of the magnetic sensor unit 3a. The external I / F 12 outputs measurement data indicating the magnetic measurement results in the X-axis and Y-axis directions from the temporary register to the control unit 11 based on the output command. The external I / F 17 outputs measurement data indicating the result of magnetic measurement in the Z-axis direction from the temporary register to the control unit 11 based on the output command.

  In the present embodiment, the magnetic measurement circuit is described as being mounted on a portable terminal. However, the above description does not prevent the magnetic measurement circuit from being mounted on another device. Further, the description has been given on the assumption that the X-axis and Y-axis two-axis magnetic sensors are provided in the same chip. .

  As described above, according to the present embodiment, the magnetism in two axes among three axes is continuously measured, and the magnetism in the remaining one axis is measured in parallel with the measurement of magnetism in the other two axes. By measuring, the time required for magnetic measurement can be shortened. Further, the control unit 11 instructs the magnetic sensor units 2a and 3a to start the magnetic measurement in parallel, and the X / Y switching control unit 13 inside the magnetic sensor unit 2a finishes the magnetic measurement by the magnetic sensor X14. Subsequently, by starting the measurement of magnetism by the magnetic sensor Y15, the magnetic measurement in the biaxial direction can be performed with only one command output to the magnetic sensor unit 2a by the control unit 11, and one command can be obtained. Can be shortened.

  In addition, the circuit scale is smaller than when three axes are continuously measured. Furthermore, it is possible to perform magnetic measurement of only two of the three axes.

  As described above, the embodiments of the present invention have been described in detail with reference to the drawings, but the specific configuration is not limited to these embodiments, and includes design changes and the like within a scope not departing from the gist of the present invention. It is.

It is a block diagram which shows the structure of the magnetic measurement circuit by one Embodiment of this invention. It is a block diagram which shows the function structure which concerns on the magnetic measurement of the magnetic measurement circuit by the embodiment. It is a timing diagram which shows the timing of the magnetic measurement in the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... CPU, 2, 3, 2a, 3a ... Magnetic sensor unit, 11 ... Control part (control means, 1st control unit), 12, 17 ... External I / F, 13. ..X / Y switching control unit (control means, second control unit), 14 ... magnetic sensor X (magnetic measurement means, first magnetic sensor), 15 ... magnetic sensor Y (magnetic measurement means, 3rd magnetic sensor), 16, 19 ... ADC, 18 ... magnetic sensor Z (magnetic measuring means, second magnetic sensor), 21 ... X-axis magnetic sensor, 22 ... Y-axis magnetism Sensor, 23, 34 ... Switch, 24, 33 ... Amplifier circuit, 25, 35 ... A / D, 26, 36 ... Control circuit, 27, 37 ... Interface, 31 ... Z-axis magnetic sensor, 32... Tilt sensor.

Claims (3)

Magnetic measuring means for measuring magnetism in three axial directions;
The magnetism measuring means is controlled so as to continuously measure the magnetism in the two-axis direction among the three-axis directions and measure the remaining magnetism in the one-axis direction in parallel with the measurement of the magnetism in the two-axis direction. Control means;
A magnetic measurement circuit comprising: The magnetic measurement means includes a first magnetic sensor, a second magnetic sensor, and a third magnetic sensor that measure magnetism in each of the three axial directions.
The control means controls the first magnetic sensor and the second magnetic sensor so that the first magnetic sensor and the second magnetic sensor measure magnetism in parallel. 2. The magnetic measurement circuit according to claim 1, wherein the third magnetic sensor is controlled so that the third magnetic sensor continuously measures magnetism after the measurement of magnetism by the magnetic sensor is finished. 3. A first magnetic sensor unit including the first magnetic sensor and the third magnetic sensor;
A second magnetic sensor unit including the second magnetic sensor;
With
The control means includes
A first control unit for instructing in parallel the start of measurement of magnetism for the first magnetic sensor unit and the second magnetic sensor unit;
A second control unit configured to start measurement of magnetism by the third magnetic sensor after the measurement of magnetism by the first magnetic sensor in the first magnetic sensor unit;
The magnetic measurement circuit according to claim 2, comprising:

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