JP2005345388A - Portable terminal apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically calibrate a magnetic sensor without users' awareness by eliminating the need for a special operation for calibrating the magnetic sensor by the users. <P>SOLUTION: A main controller unit 20 (control means) measures bearings on the basis of geomagnetism detected by the magnetic sensor and automatically calibrates the magnetic sensor when operations for starting conversations such as the transmission or reception of communication, onhook, etc. are detected. The calibration is performed by storing measurement data captured from the magnetic sensor in a storage device, reading the measurement data stored in the storage device, estimating an offset according to a prescribed offset estimating algorithm, and determining whether an estimated offset value is valid or not. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a portable terminal device suitable for use in applications in which a geomagnetic field is detected by a magnetic sensor, direction measurement is performed, and a map based on a current position is displayed on a screen.

  There is known a portable terminal device such as a mobile phone that includes a magnetic sensor that detects geomagnetism and performs azimuth measurement based on the geomagnetism detected by the magnetic sensor. The azimuth | direction measured here is utilized for the display of a map, for example. As an example, a mobile terminal device that has a GPS (Global Positioning System) sensor that performs position detection and has a function of displaying a map based on the current position in accordance with the orientation (azimuth) of the mobile terminal has appeared. .

By the way, in the above-described portable terminal device, there is magnetism that leaks from a speaker, a microphone, or a metal package of a magnetized electronic component. Therefore, the magnetic sensor of the mobile terminal device detects a magnetic field in which a magnetic field (offset) generated from an electronic component or the like inside the mobile terminal device is combined with the geomagnetism. For this reason, calibration for estimating the offset is required.
Conventionally, the above-described calibration is performed by obtaining a plurality of magnetic sensor measurement data when the mobile terminal device moves to some extent (when the orientation changes) and updating the offset based on the measurement data. Yes. On the other hand, there is also known a technique for rotating a mobile terminal device by a predetermined angle, estimating an offset based on data measured by a magnetic sensor at each angle, and performing calibration without depending on the rotation speed (for example, , See Patent Document 1).
JP 2004-12416 A

However, according to the related art including the above-described Patent Document 1, it is necessary for the user to change the direction of the mobile terminal device or to rotate it with the consciousness, and it is difficult to perform an operation in accordance with a request for performing calibration accurately. Met. In addition, the mobile terminal may be dropped and damaged due to this.
The present invention has been made in view of the above circumstances, and provides a portable terminal device that does not require a special user operation for calibration and can automatically perform calibration without making the user aware of it. Objective.

  In order to solve the above-described problems, the present invention provides a magnetic sensor for detecting geomagnetism, performing azimuth measurement based on the geomagnetism detected by the magnetic sensor, and detecting an operation for starting a call. And a control means for executing calibration of the magnetic sensor.

  In the present invention, the control means instructs the magnetic sensor to start measurement when an operation for starting the call is detected, and the acquired measurement data is transmitted according to a predetermined data storage determination algorithm. Data storage determination means for determining whether to store in a storage device, offset estimation means for reading measurement data stored in the storage device, and estimating an offset according to a predetermined offset estimation algorithm, and the estimated offset value Validity judging means for judging whether or not it is valid according to a predetermined validity judgment algorithm and storing the offset value judged to be valid in the storage device is provided.

  According to the present invention, for example, the calibration of the magnetic sensor is automatically executed when an operation for starting a call such as outgoing / incoming call or on-hook is detected. Calibration can be executed without requiring user operation and making the user conscious.

  FIG. 1 is a block diagram showing an embodiment of a portable terminal device according to the present invention. The mobile terminal device according to the present embodiment is a so-called foldable mobile terminal device including two housings (terminal unit (1) and terminal unit (2)). That is, the two casings are connected via a connecting portion so that the short sides of the respective housings face each other, and pass through the connecting portion and center on an axis parallel to the main surface of the casing. The casing is configured to be rotatable with respect to the other casing, and the two casings can be folded so as to overlap each other in the thickness direction of the casing. In addition, the portable terminal device has a GPS positioning function and a CDMA (Code Division Multiple Access) communication function. Hereinafter, each component in the figure will be described.

The antenna 11 transmits and receives radio waves with a radio base station (not shown). The RF unit 12 performs processing related to signal transmission / reception. The RF unit 12 includes a local oscillator and the like, and converts a received signal into a received IF signal of an intermediate frequency (IF) by mixing a locally transmitted signal of a predetermined frequency with a received signal output from the antenna 11 during reception. And output to the modem unit 13. In addition, the RF unit 12 converts a transmission IF signal into a transmission signal having a transmission frequency by mixing a local transmission signal having a predetermined frequency with a transmission IF signal having an intermediate frequency during transmission, and outputs the transmission signal to the antenna 11.
The modem unit 13 performs demodulation processing on received signals and modulation processing on transmitted signals. The modulation / demodulation unit 13 includes a local oscillator and the like, converts the received IF signal output from the RF unit 12 into a baseband signal having a predetermined frequency, converts the baseband signal into a digital signal, and outputs the digital signal to the CDMA unit 14. . Further, the modem unit 13 converts the digital baseband signal for transmission output from the CDMA unit 14 into an analog signal, converts it into a transmission IF signal of a predetermined frequency, and outputs it to the RF unit 12.
The CDMA unit 14 performs an encoding process on a transmitted signal and a decoding process on a received signal. The CDMA unit 14 decodes the baseband signal output from the modem unit. Also, the CDMA unit 14 encodes a transmission signal, converts it into a baseband signal, and outputs it to the modem unit 13.

  The voice processing unit 15 performs processing related to voice during a call. The voice processing unit 15 converts an analog voice signal output from the microphone 16 during a call into a digital signal and outputs the digital signal to the CDMA unit 14 as a transmission signal. The voice processing unit 15 also generates an analog drive signal for driving the speaker based on a signal indicating the voice data decoded by the CDMA unit 14 during a call, and outputs the analog drive signal to the speaker. The microphone 16 generates an audio signal based on the audio input by the user and outputs the audio signal to the audio processing unit 15. The speaker 21 generates the other party's voice based on the signal output from the voice processing unit.

The GPS antenna 17 receives a radio wave transmitted from a GPS satellite (not shown), and outputs a reception signal based on this radio wave to the GPS receiver 18. The GPS receiver 18 demodulates the received signal, and acquires accurate time information of GPS satellites and information such as radio wave propagation time based on the received signal. The GPS receiver 18 calculates a distance to three or more GPS satellites based on the acquired information, and calculates a position (latitude, longitude, altitude, etc.) in a three-dimensional space based on the principle of triangulation.
The sensor data acquisition unit 19 includes a magnetic sensor that detects magnetism (magnetic field) in each of the X-axis, Y-axis, and Z-axis orthogonal to each other, a temperature sensor that detects temperature, and a physical quantity sensor that detects the tilt of the mobile terminal And a sensor control unit that processes (A / D conversion) the detection results of the sensors. Each of these sensors will be described later.

The main control unit 20 controls each unit inside the mobile terminal device. The main control unit 20 includes an RF unit 12, a modulation / demodulation unit 13, a CDMA unit 14, an audio processing unit 15, a GPS reception unit 18, a sensor data acquisition unit 19, a ROM 31, and a RAM 32 and a control signal or data input via a bus. Output. The ROM 31 stores various programs executed by the main control unit 20, initial characteristic values of the temperature sensor and the tilt sensor measured at the time of shipping inspection, and the like. The RAM 32 temporarily stores data processed by the main control unit 20.
The notification unit 33 includes, for example, a speaker, a vibrator, or a light emitting diode, and notifies the user of an incoming call or mail reception by sound, vibration, light, or the like. The clock unit 34 has a clocking function, and generates clocking information such as year, month, date, day of the week, and time. The main operation unit 35 includes an input key for character input operated by the user, a conversion key for conversion of kanji and numbers, a cursor key for cursor operation, a power on / off key, a call key, a redial key, and the like. And a signal indicating an operation result by the user is output to the main control unit 20.

  The electronic image pickup unit 22 includes an optical lens and an image pickup device such as a CCD (Charge Coupled Device), converts an image of a subject formed on the image pickup surface of the image pickup device by the optical lens into an analog signal, and outputs the analog signal. The signal is converted into a digital signal and output to the main control unit 20. The display unit 23 includes a liquid crystal display and the like, and displays images, characters, and the like based on display signals output from the main control unit 20. The touch panel 24 is incorporated in the surface of the liquid crystal display included in the display unit 23, and outputs a signal based on the operation content by the user's pressing to the main control unit 20. The sub operation unit 25 includes a push switch used for display switching.

FIG. 2 and FIG. 3 are block diagrams showing functional expansion of the internal configuration of the mobile terminal device according to the embodiment of the present invention.
The main control unit 20 serving as a control center of the mobile terminal device of the present invention is roughly divided into two parts: a sensor data acquisition unit 19 (FIG. 2) and an orientation data calculation unit 200 (FIG. 3).
In the sensor data acquisition unit 19 illustrated in FIG. 2, the magnetic sensor unit 191 includes magnetic sensors 41 to 43 and sensor initialization units 44 to 46 that initialize the magnetic sensors 41 to 43 after the power is turned on. The sensor initialization means 44 to 46 are used for resetting the magnetization direction of the magnetic material in the magnetic sensors 41 to 43 when a strong magnetic field is applied. The inclination sensor unit 192 includes a physical quantity sensor 51 (inclination sensor), an inclination sensor initial value storage means 52 that stores in advance initial values indicating values such as offset and sensitivity of the output value of the physical quantity sensor 51, and at the time of measurement. Inclination sensor correction means 53 for correcting the output of the physical quantity sensor 51 based on the initial value stored in the inclination sensor initial value storage means 52 is provided. The temperature sensor unit 193 includes a temperature sensor 61, a temperature sensor initial value storage means 62 that stores initial values indicating values such as offset and sensitivity of the output value of the temperature sensor 61 in advance, and a temperature sensor initial value at the time of measurement. Temperature sensor correction means 63 for correcting the output of the temperature sensor based on the initial value stored in the storage means 62 is provided.

  The switching unit 194 switches outputs from the magnetic sensor unit 191, the tilt sensor unit 192, and the temperature sensor unit 193, and inputs an analog signal output from any one of the sensor units 191 to 193 to the A / D conversion circuit 195. . The A / D conversion circuit 195 converts this analog signal into a digital signal. The scan range setting unit 196 quantizes the output voltage of each of the sensors 191 to 193 and converts the voltage range and the quantization unit (for example, quantizing in increments of 0.1 mV) as a conversion unit when the digital conversion is performed. Set every 193.

In the azimuth data calculation unit 200 shown in FIG. 3, the data storage determination unit 201 determines whether or not the measurement data indicated by the digital signals corresponding to the outputs of the magnetic sensors 41 to 43 should be stored in the storage unit 204 during calibration. Processes related to data storage, such as The offset estimation unit 202 estimates an offset based on the measurement data. The validity determination unit 203 determines the validity of the offset estimated by the offset estimation unit 202. The storage unit 204 stores measurement data and the like.
The azimuth calculating means 205 calculates the azimuth based on the measurement data during the azimuth calculation. The offset removing unit 206 removes the offset from the measurement data. The temperature correction unit 207 performs temperature correction on the measurement data when temperature correction of the measurement data is necessary. The tilt correction unit 208 performs tilt correction on the measurement data when tilt correction is necessary. The display unit 23 displays the azimuth calculated by the azimuth calculation means 205 as an image.

Hereinafter, the operation of the azimuth data calculation unit 200 will be described. At the time of calibration, measurement data is input to the data storage determination unit 201. The data storage determination unit 201 determines whether or not the measurement data should be stored in the storage unit 204 based on the data storage determination algorithm. As a result of the determination, if it is determined that the measurement data should be stored in the storage unit 204, the data storage determination unit 201 stores the measurement data in the storage unit 204. The data storage determining unit 201 counts the number of measurement data stored in the storage unit 204, and stops storing the measurement data in the storage unit 204 when the number of measurement data reaches a predetermined number. The offset estimation means 202 is instructed to estimate the offset.
When the data storage determination unit 21 is instructed to estimate the offset, the offset estimation unit 202 reads the measurement data from the storage unit 204 and estimates the offset based on the offset estimation algorithm. The offset estimation unit 202 notifies the validity determination unit 203 of the offset estimation result. When the offset estimation unit 202 is notified of the offset estimation result, the validity determination unit 203 reads the estimation data from the storage unit 204 and determines whether the estimated offset is valid based on the validity determination algorithm. judge. If the estimated offset is valid, the validity determination unit 203 stores this offset in the storage unit.

At the time of azimuth calculation, measurement data is input to the azimuth calculation means 205. This measurement data is magnetic data, temperature data, and inclination data. The azimuth calculating means 205 outputs magnetic data and temperature data to the offset removing means 206. When these measurement data are input, the offset removing unit 206 reads the offset from the storage unit 204, corrects the offset by removing the offset from the magnetic data, and sends the corrected magnetic data to the azimuth calculating unit 205. Output.
Further, the azimuth calculation means 205 instructs the offset removal means 206 to correct the temperature of the magnetic data as necessary. Upon receiving this instruction, the offset removing unit 206 outputs temperature data to the temperature correcting unit 207. The temperature correction unit 207 reads the temperature data at the time of calibration from the storage unit 204, corrects the current magnetic data based on the current temperature and the temperature at the time of calibration, and notifies the offset removal unit 206 of the correction result. To do. The offset removing unit 206 outputs the corrected magnetic data to the azimuth calculating unit 205 based on the correction result.

In addition, the azimuth calculation unit 205 outputs magnetic data and tilt data to the tilt correction unit 208 as necessary, and instructs the tilt correction of the magnetic data. In response to this instruction, the tilt correction unit 208 reads data necessary for tilt correction from the storage unit 204, performs tilt correction of the magnetic data based on the data, and outputs the corrected magnetic data to the azimuth calculation unit 205. . Specifically, a conversion table in which magnetic data, an azimuth angle, and an inclination angle are associated with each other is prepared in advance, and the inclination correction of the magnetic data is performed based on the conversion table.
The azimuth calculation means 205 calculates the azimuth based on the corrected magnetic data and notifies the display unit 23 of the calculated azimuth. The display unit 23 displays, for example, information indicating the direction on the map. For the calculation of the azimuth, a method described in Japanese Patent Application Laid-Open No. 2003-90725 may be used.

FIG. 4 is a flowchart cited for explaining the calibration operation of the portable terminal device according to the embodiment of the present invention. The operation of the embodiment of the present invention shown in FIGS. 1 to 3 will be described in detail below with reference to the flowchart shown in FIG.
First, main controller 20 detects a trigger indicating the start of offset estimation. Here, an outgoing / incoming operation or an off-hook operation is an operation for starting a call. In other words, when starting a call, the magnetic sensor calibration is performed with the operation of bringing the mobile phone terminal device to the position of the face (ear) after holding the mobile terminal device in a state of being tilted in front of the body. Is executed. The details are shown in FIG. For example, when a mobile terminal device receives an incoming call and starts a call, the mobile terminal device is first held in front (FIG. 5 (a)), and the screen display is confirmed (FIG. 5 (b)). The position is moved (FIG. 5C). This operation is an operation at the time of calibration. Therefore, the trigger is an incoming / outgoing call or an off-hook operation, which are detected by the main control unit 20, and thereafter, as shown in FIGS. 5 (a) and 5 (c), the mobile terminal device moves from the Z axis. It will change to the Y axis.

Subsequently, the main control unit 20 instructs the magnetic sensors 41 to 43 to perform measurement based on the trigger detection described above (S32). Then, the data X, Y, and Z are read from the magnetic sensors 41 to 43 (S33), and it is determined whether to store the measurement data in the RAM 32 based on the data storage determination algorithm (S34). Since this data storage determination algorithm captures data only when the user hardly moves the mobile terminal device, the measurement data is concentrated near the same point on the azimuth circle (or azimuth sphere) This is to prevent the data density from being mottled because the operation speed is not uniform.
Here, when it determines with No, it waits for 0.1 second (S40), and returns to the process of step S32. If it is determined Yes, the measurement data is stored in the RAM 32 (S35), and it is determined whether the number of measurement data stored in the RAM 32 has reached a predetermined number (S36). Here, when it determines with No, it progresses to the process of above-mentioned step S40. If the determination is Yes, the sampling of the measurement data is stopped, the measurement data is read from the RAM 32, and the offset is estimated based on the offset estimation algorithm (S37). Subsequently, the azimuth data calculation unit 200 determines whether the estimated offset is a valid value based on the validity determination algorithm (S38). Here, when it determines with Yes, the estimated offset is stored in RAM32 (S39), and a process is complete | finished. If it is determined No, the process ends.

Here, it supplements about an azimuth | direction circle. When the mobile terminal device rotates in a horizontal plane, the output X of the magnetic sensor 41 converted into the magnetic field value changes in a sine wave shape, and the output Y of the magnetic sensor 42 converted into the magnetic field value has a phase 90 with respect to the output X. It changes in a sinusoidal shape that differs by a degree. When the offset is (X0, Y0), the following relational expression (1) is established (this is defined as an azimuth circle).
(X−X0) ² + (Y−Y0) ² = R ² (1)
The above is a two-dimensional case, but the following relational expression (2) is similarly established in the three-dimensional case.
(X−X0) ² + (Y−Y0) ² + (Z−Z0) ² = R ² (2)

  Subsequently, the data storage determination algorithm will be supplemented. The data stored in the RAM 32 immediately before is (X0, Y0, Z0), the data to be subjected to storage determination is (X, Y, Z), and the data (X , Y, Z) are stored in the RAM 32. The value of d is preferably about 1/10 of the azimuth radius, and is expressed by the following arithmetic expression (3).

Next, the offset estimation algorithm will be supplemented. When the measurement data is (x _i , y _i , z _i ) (i = 1,..., N), the offset is (X0, Y0, Z0), and the azimuth circle radius is R, the following relational expression (4) Holds.
(x _i -X0) ² + (y _i -Y0) ² + (z _i -Z0) ² = R ² (4)
Here, the least square error ε is defined as the following equation (5).

Here, a = x _i ² + y _i ² + z _i ² , b = −2x _i , c = −2y _i , d = −2z _i
D = (X0 ² + Y0 ² + Z0 ² ) −R ² (6)
Then, ε is expressed by the following arithmetic expression (7).

The condition for minimizing the least square error ε is the following equation (8).

Therefore, the following arithmetic expression (9) is established.

However, m is defined by the following arithmetic expression (10).

  X0, Y0, Z0, and D that minimize the minimum square error ε can be obtained by solving the above simultaneous equations (calculation formula 9). Further, R is also obtained from the arithmetic expression (6).

  Next, the effectiveness determination algorithm will be described. Here, values represented by the following arithmetic expressions (11) to (14) are calculated from the estimated offset and azimuth circle radius and the measurement data stored in the RAM 32.

However, Max _{(x i)} is the minimum in the measurement data _x 1, · · ·, represents the maximum value among the _{x N,} Min _{(x i),} the measurement data _x 1, ···, _{x N} Represents a value. Σ is a standard deviation. It is determined whether or not the following determination criterion is satisfied with respect to the above value, and when the determination criterion is satisfied, it is determined that the estimated offset is valid.
σ <F
w _x > G
w _y > G
w _z > G
Here, F is preferably about 0.1. G is preferably about 1.

  As described above, according to the present invention, for example, calibration of the magnetic sensor is automatically executed when an operation for starting a call such as outgoing / incoming call or on-hook is detected. Therefore, calibration can be executed without making the user aware of this.

It is a block diagram which shows one Embodiment of the portable terminal device concerning this invention. It is a functional block diagram of the portable terminal device concerning an embodiment of the present invention. It is a functional block diagram of the portable terminal device concerning an embodiment of the present invention. It is the flowchart quoted in order to demonstrate operation | movement of this invention embodiment. It is the figure quoted in order to demonstrate rotation operation | movement at the time of the incoming call of the portable terminal concerning embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 19 ... Sensor data acquisition part, 20 ... Main control part, 41-43 ... Magnetic sensor, 200 ... Direction data calculation part, 201 ... Data storage determination means, 202 ... Offset estimation means, 203 ... Effectiveness determination means, 204 ... Memory means

Claims (2)

A magnetic sensor for detecting geomagnetism,
Control means for performing azimuth measurement based on the geomagnetism detected by the magnetic sensor, and performing calibration of the magnetic sensor when an operation for starting a call is detected,
A portable terminal device comprising: The control means includes
When the operation for starting the call is detected, the magnetic sensor is instructed to start measurement, and it is determined whether or not the captured measurement data is stored in the storage device according to a predetermined data storage determination algorithm. Data storage judging means;
An offset estimation means for reading measurement data stored in the storage device and estimating an offset according to a predetermined offset estimation algorithm;
Whether the estimated offset value is valid is determined according to a predetermined validity determination algorithm, and the validity determination means for storing the offset value determined to be valid in the storage device;
The mobile terminal device according to claim 1, further comprising:

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