JP4161985B2 - Portable electronic device with orientation detection function and calibration method thereof - Google Patents

Description

  The present invention relates to a portable electronic device with an azimuth detection function, and more particularly to a technique for facilitating calibration of the output of a magnetic sensor mounted on a folding portable electronic device.

  A portable terminal 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 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) sensor for detecting a position 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.

  However, since a mobile terminal has magnetism leaking from a speaker and a microphone mounted on the mobile terminal and a metal package of a magnetized electronic component, the magnetic sensor mounted on the mobile terminal is an electronic component inside the mobile terminal. Thus, a magnetic field generated by combining the magnetic field generated from the magnetic field and the geomagnetism is detected. Therefore, calibration for correcting an error (offset) due to a magnetic field generated from an electronic component or the like inside the portable terminal is required. Conventionally, in order to perform calibration, the user has performed an operation of rotating the mobile terminal, for example, 180 degrees. During this operation, the mobile terminal collects measurement data from the magnetic sensor and estimates an offset based on the measurement data.

Regarding the calibration of such a magnetic sensor mounted on a portable terminal, there is a technique disclosed in Patent Document 1, for example. In this technology, the portable terminal is rotated by a predetermined angle, and the offset is estimated based on data measured by the magnetic sensor at each angle, so that calibration can be performed without depending on the rotation speed. .
JP 2004-12416 A

  However, even in the method described in Patent Document 1, the user must consciously rotate the portable device on which the magnetic sensor is mounted and calibrate the portable device. Therefore, it is troublesome for the user. In addition, if the user neglects or forgets calibration, the geomagnetic sensor cannot be operated in an optimum state.

  The present invention has been made in view of the above points, and an orientation detection function that can easily perform calibration of orientation detection means including a magnetic sensor mounted on a folding portable electronic device without imposing a burden on the user. A portable electronic device and a calibration method thereof are provided.

In order to solve the above-described problem, the portable electronic device with an orientation detection function according to the first aspect of the invention is a folding portable electronic device equipped with an orientation detection means having a magnetic sensor, and detects opening and closing of the portable electronic device. an opening and closing detection means for a data storage means for storing a plurality of output data of the magnetic sensor, the data storage of the output data of said magnetic sensor at the timing or closing timing of opening the portable electronic device is detected by the opening and closing detecting means An offset value used to correct the output of the magnetic sensor by starting storage in the device, estimating an offset that is an error in the output of the magnetic sensor based on a plurality of output data stored in the data storage device And a control means for updating.

  According to a second aspect of the present invention, in the portable electronic device with an orientation detection function according to the first aspect, the magnetic sensor is fixed to the folding portable electronic device and one unit of the portable electronic device is fixed. It is provided on the other unit side to be moved when opened.

  According to a third aspect of the present invention, in the portable electronic device with an orientation detection function according to the first or second aspect, the magnetic sensor is provided at a position away from the magnetic source. .

  According to a fourth aspect of the present invention, in the portable electronic device with an orientation detection function according to any one of the first to third aspects, the control means determines that the offset estimation is invalid. The control means performs control for instructing the user to further open or close the foldable portable electronic device.

  According to a fifth aspect of the present invention, in the portable electronic device with an orientation detection function according to any one of the first to third aspects, the offset is determined to be invalid by the control means. In this case, the control means performs control for instructing the user to open or close the folding portable electronic device in a plurality of directions.

According to a sixth aspect of the present invention, there is provided a folding method for a portable electronic device with an orientation detection function, which is a folding type equipped with an orientation detection means comprising a magnetic sensor and a data storage means for storing a plurality of output data of the magnetic sensor . A method for calibrating a direction detecting means in a portable electronic device, wherein the opening / closing of the portable electronic device is detected, and the output data of the magnetic sensor is stored in the data storage means at the timing of opening or closing the portable electronic device. Starting offset, estimating an offset which is an error in the output of the magnetic sensor based on a plurality of output data stored in the data storage means, and updating an offset value used for correcting the output of the magnetic sensor. It is a feature.

The portable electronic device with an orientation detection function according to claim 7 is the portable electronic device with an orientation detection function according to any one of claims 1 to 5, wherein the plurality of output data and the estimated offset are A standard deviation calculating unit that calculates a standard deviation of the distance on the coordinates; and an effectiveness determining unit that determines the effectiveness of the estimated offset based on the calculated standard deviation. .

The portable electronic device with azimuth detection function according to claim 8 is the portable electronic device with azimuth detection function according to any one of claims 1 to 5, wherein the X, Y, and Z axes are orthogonal to each other. detection of the magnetic data with the magnetic sensitive direction _{(x i, y i, z} i) (i = 1,2, ..., N) and means for reading, a minimum square error defined in Equation 6],

For [Equation 7] obtained by modifying [Equation 6] with a _i = x _i ² + y _i ² + z _i ² , b _i = −2x _i , c _i = −2y _i , d _i = −2z _i ,

The condition [Equation 8] that minimizes the least square error ε is

  By solving the equation shown in [Equation 10] using the notation of [Equation 9]

  Means for obtaining an offset (X0, Y0, Z0) of the magnetic sensor.

According to the present invention, since the calibration of the azimuth detecting means is automatically performed at the time of opening / closing operation of the folding portable electronic device, the calibration is easy without forcing the user to perform the calibration operation.
Further, conventionally, when the user neglects or forgets the calibration operation, the geomagnetic sensor could not be operated in an optimum state. However, in the present invention, when the portable electronic device is normally used Since calibration is automatically performed during the opening / closing operation, there is no such problem.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an electric diagram of a mobile communication terminal (hereinafter referred to as a mobile terminal) using a CDMA (Code Division Multiple Access) communication system, which is an embodiment of the mobile electronic device with an orientation detection function of the present invention. It is a block diagram which shows a typical structure.
In the following description, the same reference numerals are given to portions common to the respective drawings to be referred to.

  The mobile terminal 1 according to the present embodiment has a so-called foldable structure including two housings (terminal unit-1 and terminal unit-2). That is, the two housings are connected via a connecting portion (not shown), and the terminal unit-1 and the terminal unit-2 are configured to be openable and closable around the rotation axis of the connecting portion. The folding portable terminal starts to open perpendicularly to the main surface of the portable terminal (the surface where the terminal unit-1 and the terminal unit-2 overlap in the closed state) from the state where the two units overlap, and the rotation axis remains unchanged. There are a general foldable type that rotates to the center and a revolver type that can be freely opened and closed by rotating the terminal unit-1 and the terminal unit-2 parallel to the main surface of the mobile terminal. In this embodiment, when particularly distinguishing, a general foldable type and a revolver type are distinguished, but a revolver type portable terminal is also included in the foldable type portable terminal.

Next, the electrical configuration of the mobile terminal 1 of the present embodiment will be described.
An antenna 101 shown in FIG. 1 transmits and receives radio waves to and from a radio base station (not shown). The RF unit 102 performs processing related to signal transmission / reception. This RF unit 102 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 101 during reception. And output to the modem 103. Further, the RF unit 102 mixes a local transmission signal having a predetermined frequency with a transmission IF signal having an intermediate frequency during transmission, thereby converting the transmission IF signal into a transmission signal having a transmission frequency and outputting the signal to the antenna 101.

The modem 103 performs demodulation processing on the received signal and modulation processing on the transmitted signal. The modulation / demodulation unit 103 includes a local oscillator and the like, converts the received IF signal output from the RF unit 102 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 104. . Further, the modem unit 103 converts the digital baseband signal for transmission output from the CDMA unit 104 into an analog signal, converts it into a transmission IF signal having a predetermined frequency, and outputs the signal to the RF unit 102.
The CDMA unit 104 performs encoding processing of a transmitted signal and decoding processing of a received signal. The CDMA unit 104 decodes the baseband signal output from the modem unit 103. The CDMA unit 104 encodes a transmission signal and outputs the encoded baseband signal to the modem unit 103.

  The voice processing unit 105 performs processing related to voice during a call. The voice processing unit 105 converts an analog voice signal output from a microphone (MIC) during a call into a digital signal and outputs the digital signal to the CDMA unit 104 as a transmission signal. Also, the voice processing unit 105 generates an analog drive signal for driving the speaker (SP) based on a signal indicating the voice data decoded by the CDMA unit 104 during a call, and sends the analog drive signal to the speaker (SP). Output. The microphone (MIC) generates an audio signal based on the audio input by the user and outputs the audio signal to the audio processing unit 105. The speaker (SP) emits the other party's voice based on the signal output from the voice processing unit 105.

  The GPS antenna 106 receives a radio wave transmitted from a GPS satellite (not shown) and outputs a reception signal based on this radio wave to the GPS receiving unit 107. The GPS receiver 107 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 receiving unit 107 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 main control unit 108 includes a CPU (Central Processing Unit) and the like, and controls each unit inside the mobile terminal 1. The main control unit 108 includes an RF unit 102, a modem unit 103, a CDMA unit 104, an audio processing unit 105, a GPS reception unit 107, a sensor data acquisition unit 201, a ROM 109, and a RAM 110, and a control signal or data via a bus. I / O is performed. The ROM 109 stores various programs executed by the main control unit 108, initial characteristic values of the temperature sensor and the tilt sensor measured at the time of shipping inspection, and the like. The RAM 110 temporarily stores data processed by the main control unit 108.

  The notification unit 111 includes, for example, a speaker, a vibrator, a light emitting diode, or the like, and notifies the user of an incoming call or mail reception by sound, vibration, light or the like. The clock unit 112 has a clocking function, and generates clocking information such as year, month, day, day of the week, and time. The main operation unit 113 includes input keys for character input operated by the user, conversion keys for conversion of kanji and numbers, cursor keys for cursor operation, power on / off key, call key, redial key, and the like. And outputs a signal indicating the operation result of the user to the main control unit 108. The open / close switch (SW) 114 is a switch for detecting the opening and closing ends of the folding portable terminal.

  The sensor data acquisition unit 201 includes magnetic sensors (1) to (3) that detect magnetism (magnetic fields) in the axial directions of the X axis, the Y axis, and the Z axis that are orthogonal to each other, a temperature sensor that detects temperature, and a portable terminal 1 includes a physical quantity sensor that detects the inclination of 1 and a sensor control unit that processes (A / D conversion, etc.) the detection results of the sensors.

  The electronic imaging unit 202 includes an optical lens and an imaging device such as a CCD (Charge Coupled Device), converts an image of a subject formed on the imaging surface of the imaging device by the optical lens into an analog signal, and converts the analog signal to the analog signal. The signal is converted into a digital signal and output to the main control unit 108. The display unit 203 includes a liquid crystal display or the like, and displays images, characters, and the like based on display signals output from the main control unit 108. The touch panel 204 is incorporated on the surface of the liquid crystal display included in the display unit 203 and outputs a signal corresponding to the operation content by the user to the main control unit 108. The sub-operation unit 205 includes a push switch used for display switching.

Here, the functional block diagram shown in FIG. 2 will be described.
1 corresponds to the main control unit 108 illustrated in FIG. 1, and the display unit 316 corresponds to the display unit 203 illustrated in FIG.

  The magnetic sensor unit 301 includes magnetic sensors (1) to (3) and sensor initialization means (1) to (3) for initializing each magnetic sensor after the power is turned on. When the strong magnetic field is applied to the sensor initialization means (1) to (3), the direction of magnetization of the magnetic bodies of the magnetic sensors (1) to (3) is out of order. This is provided to reset (3) to the initial state.

The inclination sensor unit 302 includes a physical quantity sensor (inclination sensor), an inclination sensor initial value storage unit that stores initial values indicating values such as offset and sensitivity of output values of the physical quantity sensor in advance, and an initial inclination sensor at the time of measurement. Inclination sensor correction means for correcting the output of the physical quantity sensor based on the initial value stored by the value storage means.
The temperature sensor unit 303 includes a temperature sensor, temperature sensor initial value storage means for storing initial values indicating values such as offset and sensitivity of the output value of the temperature sensor in advance, and temperature sensor initial value storage means for measurement. Temperature sensor correction means for correcting the output of the temperature sensor based on the stored initial value.

  The switching unit 304 switches outputs from the magnetic sensor unit 301, the tilt sensor unit 302, and the temperature sensor unit 303, and inputs an analog signal output from any one of the sensor units to the A / D conversion circuit 305. The A / D conversion circuit 305 converts this analog signal into a digital signal. The scan range setting unit 306 sets a voltage range and a quantization unit (for example, quantization in increments of 0.1 mV) as a conversion unit when the output voltage of each sensor is quantized and digitally converted for each sensor.

  In the azimuth data calculation unit 307, the data storage determination unit 308 performs processing related to data storage such as determination of whether or not the measurement data indicated by the digital signal corresponding to the output of the magnetic sensor should be stored in the storage unit during calibration. Do. The offset estimation means 310 estimates the offset based on the measurement data acquired at the time of calibration (details will be described later). The validity determination unit 311 determines the validity of the offset estimated by the offset estimation unit 310 (details will be described later). The storage unit 309 stores measurement data and the like.

  The azimuth calculating means 312 calculates the azimuth based on the measurement data acquired at the time of azimuth calculation. The offset removing unit 313 removes the offset from the measurement data acquired during the azimuth calculation. The temperature correction means 314 performs temperature correction on the measurement data when temperature correction of the measurement data is necessary. The tilt correction unit 315 performs tilt correction on the measurement data when tilt correction is necessary. The display unit 316 displays the azimuth calculated by the azimuth calculation unit 312 as an image.

Here, the details of the operation of the azimuth data calculation unit 307 will be described.
At the time of calibration, measurement data output from the sensor data acquisition unit 201 is input to the data storage determination unit 308. The data storage determination unit 308 determines whether or not the measurement data should be stored in the storage unit 309 based on the data storage determination algorithm. If it is determined that the measurement data should be stored in the storage unit 309 as a result of the determination, the data storage determination unit 308 stores the measurement data in the storage unit 309. The data storage determination unit 308 counts the number of measurement data stored in the storage unit 309, and stops storing the measurement data in the storage unit 309 when the number of measurement data reaches a predetermined number. The offset estimation unit 310 is instructed to estimate the offset.

  When the data storage determination unit 308 is instructed to estimate the offset, the offset estimation unit 310 reads the measurement data from the storage unit 309 and estimates the offset based on the offset estimation algorithm. The offset estimation unit 310 notifies the validity determination unit 311 of the offset estimation result. The validity determination unit 311 reads out the measurement data from the storage unit 309 when the offset estimation unit 310 is notified of the offset estimation result, 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 311 stores this offset in the storage unit 309.

  At the time of azimuth calculation, measurement data output from the sensor data acquisition unit 201 is input to the azimuth calculation means 312. This measurement data is magnetic data, temperature data, and inclination data. The azimuth calculating means 312 outputs magnetic data and temperature data to the offset removing means 313. When these measurement data are input, the offset removing unit 313 reads the offset from the storage unit 309, corrects the offset by removing the offset from the magnetic data, and sends the corrected magnetic data to the azimuth calculating unit 312. Output.

  In addition, the azimuth calculation unit 312 instructs the offset removal unit 313 to correct the temperature of the magnetic data as necessary. Upon receiving this instruction, the offset removing unit 313 outputs temperature data to the temperature correcting unit 314. The temperature correction unit 314 reads temperature data at the time of calibration from the storage unit 309, corrects the current magnetic data based on the current temperature and the temperature at the time of calibration, and notifies the offset removal unit 313 of the correction result. To do. Based on the correction result, the offset removal unit 313 outputs the temperature-corrected magnetic data after the offset removal to the azimuth calculation unit 312.

Specifically, the temperature at the time of calibration is TO, the estimated offset is OF, the temperature coefficient A (this is measured at the time of shipping inspection and recorded in the ROM 109), the temperature at the time of measurement is T, and the magnetic sensor If the measured value of S0 is S0, the magnetic data S1 after temperature correction and offset removal is
S1 = S0− {OF + A (T−TO)}.

In addition, the azimuth calculation means 312 performs tilt correction as necessary.
Here, the details of the inclination correction will be described.
Here, the coordinate system of the portable terminal 1 is defined as shown in FIG. That is, the azimuth angle of the antenna 101 of the mobile terminal 1 is α, the elevation angle is β, and the twist angle (rotation angle around the antenna axis) is γ. The sign is positive in the direction of the arrow shown in the figure. Further, the unit vector in the antenna direction is Vy, and the unit vector in the direction perpendicular to the plane formed by the terminal unit-2 (the side on which the antenna 101 and the magnetic sensor unit 301 are arranged) (for example, the plane of reference numeral 99 in FIG. 3) Is Vz, and a unit vector orthogonal to both Vy and Vz is Vx. In addition, let the arrow direction shown in the figure be a positive direction. As shown in FIG. 3B, the ground coordinate system is represented by X, Y, and Z, and the north direction is the Y axis.

Here, the gravity in the ground coordinate system is G = (0, 0, Gz). Further, the gravity in the portable coordinate system is g = (gx, gy, gz). It is assumed that gravity in the portable coordinate system can be detected by an inclination sensor. Of course, gravity in the ground coordinate system is known.
Then, gravity g in the portable coordinate system and gravity G in the ground coordinate system are expressed by the following equations.
(Gx, Gy, Gz) BC = (gx, gy, gz) where

  From this, BC can be expressed by the following equation.

  Therefore, gravity g in the portable coordinate system is expressed by the following equation.

  From this equation, the elevation angle β and the twist angle γ are obtained.

From the elevation angle β and twist angle γ determined as described above, the azimuth angle α and the geomagnetic elevation angle θ can be determined. Here, if the geomagnetism in the portable coordinate system is h = (hx, hy, hz) and the geomagnetism in the ground coordinate system is H = (0, Hy, Hz),
(0, Hy, Hz) ABC = (hx, hy, hz) holds. However,

It is. From this, the following equation is derived.

Therefore,
(Hx ′, hy ′, hz ′) = (Hysin α, Hycos α, Hz). Since the elevation angle β and the twist angle γ are obtained in advance and the geomagnetism h in the portable coordinate system is measured, (hx ′, hy ′, hz ′) is determined. Here, if the geomagnetism H in the ground coordinate system is known, the azimuth angle α is obtained. The geomagnetic elevation angle θ is also obtained by the following equation.

  The azimuth calculating means 312 calculates the azimuth based on the corrected magnetic data as described above, and notifies the display means 316 of the calculated azimuth. The display unit 316 displays, for example, information indicating the direction on the map.

Next, a data storage determination algorithm will be described.
In the data storage determination algorithm, data is taken in when the user hardly moves the mobile terminal 1, and the measurement data is concentrated in the vicinity of the same point on the azimuth circle or azimuth sphere (below). This is to prevent storing measurement data that cannot be used for calibration when the data density is mottled due to non-uniformity. When such measurement data is obtained, the measurement data is not stored in the storage unit 309.

When the portable terminal 1 rotates in a horizontal plane (here, the XY plane formed by the axes of the magnetic sensor (1) and the magnetic sensor (2) is parallel to the horizontal plane), the magnetic sensor converted into a magnetic field value The output X of (1) changes in a sine wave shape, and the output Y of the magnetic sensor (2) converted into the magnetic field value changes in a sine wave shape whose phase is different from that of the output X by 90 degrees. Assuming that the offset is (X0, Y0), the following relational expression is established, and this is referred to as an azimuth circle.
(X−X0) ² + (Y−Y0) ² = R ² The same relational expression holds for the three-dimensional case, and this is referred to as an azimuth sphere.
(X−X0) ² + (Y−Y0) ² + (Z−Z0) ² = R ²

More specifically, the data storage determination algorithm uses (X0, Y0, Z0) as the data stored immediately before in the RAM 110, and (X, Y, Z) as the data to be subjected to storage determination. Only when the condition is satisfied, the data (X, Y, Z) is stored in the RAM 110.
The value of d is preferably about 1/10 of the azimuth radius.

Next, an offset estimation algorithm will be described.
When the measurement data is (x _i , y _i , z _i ) (i = 1,..., N), the offset is (X0, Y0, Z0), and the azimuth radius is R, the following relational expression is established.
(x _i −X 0) ² + (y _i −Y 0) ² + (z _i −Z 0) ² = R ² At this time, the least square error ε is defined as follows.

here,
a _i = x _i ² + y _i ² + z _i ²
b _i = -2x _i
c _i = -2y _i
d _i = −2z _i
When D = (X0 ² + Y0 ² + Z0 ² ) −R ² (1), ε is represented by the following equation.

  At this time, the condition for minimizing the least square error ε is as follows by making X0, Y0, Z0 and D independent variables of ε and differentiating ε with X0, Y0, Z0 and D.

  Therefore, the following equation holds.

However,

It is. By solving these simultaneous equations, X0, Y0, Z0, and D that minimize the minimum square error ε are obtained. In addition, R can also be obtained from equation (1).

Next, the effectiveness determination algorithm will be described.
In the processing by this algorithm, the following values are calculated from the estimated offset and the azimuth sphere (or azimuth circle) radius and the measurement data stored in the RAM 110.

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 for 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, and G is preferably about 1.

  Next, the operation relating to calibration will be described in more detail with reference to FIG.

[For revolver type mobile terminals]
In the configuration example shown in FIG. 1, each magnetic sensor is arranged on the terminal unit-2 side, which is the side that moves when the mobile terminal 1 is opened and closed (while the mobile terminal 1 is opened and closed in the terminal unit-1). When the portable terminal 1 is a revolver type, it is mounted on the side to be rotated when opening and closing (see FIG. 5). The position where this magnetic sensor is arranged is preferably closer to the portion where terminal unit-1 and terminal unit-2 are coupled (of course, it may be arranged on the terminal unit-1 side). This is because this position is usually away from the position where the microphone MIC and the speaker SP that generate magnetism are arranged. The portable terminal 1 is provided with an open / close switch (SW) 114 so that the open / close operation can be recognized at the stage of opening and closing. The magnetic sensor unit 301 may be a biaxial magnetic sensor or a triaxial magnetic sensor.

(1) Calibration method 1
First, when the opening / closing switch (SW) 114 detects the opening of the terminal unit-2, a trigger is activated at this timing (step S101). At this time, the terminal unit-2 on which the magnetic sensor unit 301 is mounted finally starts rotating (opening operation) so as to form an angle θ with the terminal unit-1 as shown in FIG.
The main control unit 108 instructs the sensor control unit to perform measurement using each sensor (step S102). Data is read from each magnetic sensor, and data sampling starts (step S103). Here, the output of each magnetic sensor is sampled continuously for a predetermined time.

Next, it is determined whether or not the measurement data is stored in the RAM 110 based on the data storage determination algorithm described above (step S104).
When it determines with No by step S104, it waits for 0.1 second (step S105), and returns to step S102.
If it is determined Yes in step S104, the measurement data is stored in the RAM 110 (step S106), and it is further determined whether or not the number of measurement data stored in the RAM 110 has reached a predetermined number (step S107).

If it is determined No in step S107, the process proceeds to step S105. On the other hand, if it is determined Yes in step S107, the sampling of the measurement data is stopped, the measurement data stored in the RAM 110 is read out, and the offset is estimated based on the offset estimation algorithm (step S108). .
Subsequently, it is determined whether the estimated offset is a valid value based on the above-described validity determination algorithm (step S109). If it is determined as Yes in this determination, the offset estimated in step S108 is stored in the RAM 110, and the update process is ended (S110). On the other hand, if it is determined No in step S109, the offset is not updated and the series of processes is terminated (step S111).

  If it is determined No in step S109, that is, if it is determined that the offset estimated in step S108 is invalid, the user is instructed to further open and close the mobile terminal 1, or the mobile terminal 1 The user may be instructed to perform opening and closing in a plurality of directions, and measurement data may be further acquired from each magnetic sensor. This increases the number of data to be measured and improves the accuracy of offset estimation. The instruction to the user is performed by, for example, generating a warning sound by the notification unit 111 and causing the display unit 203 to display the content instructed to the user.

  When the magnetic sensor unit 301 is composed of a biaxial magnetic sensor, calibration is performed as described above (by the calibration method 1). In the case where the magnetic sensor unit 301 is composed of a three-axis magnetic sensor, after the determination in step S107 in the calibration method 1 is Yes, calibration by the following calibration method 2 is further performed.

(2) Calibration method 2
Sampling is started in response to pressing a predetermined button (calibration button) on the main operation unit 113. In this calibration method 2, the user shakes the mobile terminal 1 in the direction of the arrow in FIG. 6 (note that these operations by the user are instructed by the user in advance according to the instruction manual, etc.).

The output of each magnetic sensor is sampled continuously for a predetermined time. In the revolver type, when the terminal unit-2 is rotated and opened with respect to the terminal unit-1, the terminal unit-2 is in a completely open state (the state shown in FIG. 5B). The magnetic sensor unit 301 in the terminal unit-2 operates so as to change with respect to each of the three axes. However, when θ is small, this θ The user is caused to shake the portable terminal 1 so that the measurement data can be obtained by compensating for the amount of change.
When data acquisition is completed as described above, an offset is estimated from the obtained data. Then, the offset stored in the RAM 110 is updated with the estimated offset.

The offset update processing in the calibration methods 1 and 2 is performed only when it is determined that the offset correction is necessary by comparing the offset data obtained this time with the offset data before the update (this determination). The reference may be determined separately), and the offset may be updated.
Alternatively, according to a predetermined standard, it is determined whether or not the offset is at a level (or a range of the standard) that needs to be updated, and whether to acquire data when the portable terminal 1 is opened or closed is selected. May be.

Here, an offset estimation method (another example) in the revolver type portable terminal 1 will be described.
The offset can be estimated by the above-described offset estimation algorithm. However, when the angle θ formed between the terminal unit-1 and the terminal unit-2 shown in FIG.

(A) When the magnetic sensor unit 301 is composed of a biaxial magnetic sensor The measurement data sampled by the calibration method 1 is the X sensor (magnetic sensor for detecting the magnetic force of the geomagnetism in the X axis direction), the vertical axis If the axis is plotted with the value of the Y sensor (the magnetic sensor that detects the geomagnetic force in the Y axis direction perpendicular to the X axis) (that is, the set of the output value of the X sensor and the output value of the Y sensor is plotted on the XY plane) ), As shown in FIG. This locus is a part of an ellipse, and its flatness depends on θ in FIG. 6 and the angle formed by the geomagnetism and the rotation surface (surface formed when the magnetic sensor rotates). Now, since θ is known, the angle between the X and Y offset, the geomagnetism, and the rotation plane can be obtained by obtaining the oblateness of the ellipse and the center coordinates.

(B) When the magnetic sensor part 301 consists of a triaxial magnetic sensor About the offset on XY plane, it can obtain | require similarly to the case of the biaxial of said (a). When θ is also relatively large (θ> 30 degrees) in the Z-axis direction offset, the Z offset value is used in the same manner as in the case of two axes, using the trajectory of measurement data during calibration on the XZ plane. Can be requested. However, when θ is small, there is no accuracy.
This is because, as shown in FIG. 8, the trajectory is too flat and becomes almost a straight line.

  In such a case, the Z offset may be obtained from the data sampled by the calibration method 2. In the calibration method 2, the user swings the mobile terminal 1, but when the user changes the tilt of the terminal during the orientation measurement, the output of the magnetic sensor is sampled and the measured data is used. You may make it do.

[In the case of a general folding mobile terminal]
In the configuration example shown in FIG. 1 described above, each magnetic sensor is arranged on the terminal unit-2 side, which is the side that moves when the portable terminal 1 is opened and closed. (On the other hand, when the mobile terminal 1 is opened and closed, the terminal unit-1 is generally fixed by gripping by the user's hand, etc.) That is, when the terminal unit-2 is called a lid, it is mounted on the lid side to be opened and closed. (See FIG. 9). The position where this magnetic sensor is disposed is preferably close to the portion where the terminal unit-1 and the terminal unit-2 are coupled, as in the revolver type. The portable terminal 1 has an open / close switch (SW) 114 so that the opening / closing operation can be recognized at the beginning of opening (when the terminal unit-2 is opened at a predetermined angle or more with respect to the terminal unit-1) and at the end of closing. Here, the magnetic sensor unit 301 is assumed to be a triaxial magnetic sensor.

  Also in the case of a general folding portable terminal, the processing procedure by the calibration method 1 and the calibration method 2 in the case of the above-described revolver type can be used. However, in the calibration method 2 here, when sampling the output of each magnetic sensor, the user shakes the portable terminal 1 as shown in FIG. When the mobile terminal 1 is a general foldable type shown in FIG. 9, the terminal unit-2 with the magnetic sensor unit 301 changes greatly on the surface formed by the locus when the terminal unit-2 is opened from the terminal unit-1. Since the change in the direction orthogonal to the locus (X direction) is small, the mobile terminal 1 is shaken in the direction of the arrow shown in FIG. 10 so that the change in this direction appears, and measurement data is obtained.

  As described above, when the mobile terminal 1 is a general folding mobile terminal, the offset in the Y-axis / Z-axis direction can be estimated from the measurement data obtained by the calibration method 1. The offset in the X-axis direction can be estimated from the measurement data obtained by the calibration method 2. Or it is also possible to estimate using the measurement data when the user changes the direction during azimuth measurement.

Each operation flow described above is an example, and is not limited to the above processing flow.
The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes a configuration and the like that do not depart from the gist of the present invention. Needless to say.

In the above-described embodiment, the calibration is performed at the timing when the user opens the portable terminal. However, the calibration can be performed after the user closes the portable terminal. This is because immediately after the mobile terminal is closed, the user performs an operation such as putting the mobile terminal in a pocket or placing it on a desk. Therefore, the mobile terminal changes its orientation for a while after being closed. Become. Therefore, during this time, the output of the magnetic sensor can be sampled and the offset can be estimated from this measurement data.
Further, the calibration may be performed at the timing when the user opens / closes the mobile terminal, or the user may be asked whether the calibration should be performed at the time of opening / closing.

It is a block diagram which shows the electrical constitution of the portable communication terminal (mobile terminal) which is one Embodiment of the portable electronic device with a direction detection function of this invention. It is a functional block diagram of the embodiment. (A) It is a figure which shows the coordinate system (definition) of a portable terminal, and (b) the ground coordinate system. It is a flowchart for demonstrating the operation | movement which concerns on calibration. It is a figure which shows the external appearance (a closed state and an open state) of a revolver type portable terminal. It is a figure which shows the direction which shakes a portable terminal with the calibration method 2 in a revolver type portable terminal. It is the figure (an example) which plotted the measurement data sampled by the calibration method 1 on XY plane. It is the figure (an example: when (theta) is small) which plotted the measurement data sampled by the calibration method 1 on XY plane. It is a figure which shows the external appearance (a closed state and an open state) of a common foldable portable terminal. It is a figure which shows the direction which shakes a portable terminal by the calibration method 2 in a general folding portable terminal.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Portable terminal (mobile electronic device), 101 ... Antenna, 102 ... RF part, 103 ... Modulation / demodulation part, 104 ... CDMA part, 105 ... Voice processing part, 106 ... GPS antenna, 107 ... GPS receiving part, 108 ... Main control (Control means) 109 ... ROM 110 ... RAM 111 ... notification means 112 ... clock part 113 ... main operation part 114 ... open / close switch (SW) (open / close detection means) 201 ... sensor data acquisition part ( (Azimuth detection means), 202 ... electronic imaging unit, 203 ... display unit, 204 ... touch panel, 205 ... sub-operation unit, 301 ... magnetic sensor unit, 302 ... tilt sensor unit, 303 ... temperature sensor unit, 304 ... switching unit, 305 ... A / D conversion circuit, 306 ... scan range setting means, 307 ... azimuth data calculation section, 308 ... data storage determination means, 309 ... storage means, 31 ... offset estimating means, 311 ... validity determining unit, 312 ... azimuth calculation means 313 ... offset removal means, 314 ... temperature correction means, 315 ... inclination correction unit, 316 ... display unit

Claims (8)

In a folding portable electronic device equipped with an orientation detection means having a magnetic sensor,
Open / close detecting means for detecting open / close of the portable electronic device;
Data storage means for storing a plurality of output data of the magnetic sensor;
Storage of the output data of the magnetic sensor in the data storage means is started at the opening timing or closing timing of the portable electronic device detected by the open / close detection means, and the output data stored in the data storage means And a control means for estimating an offset, which is an error in the output of the magnetic sensor, and updating an offset value used to correct the output of the magnetic sensor. machine. The direction detection function according to claim 1, wherein the magnetic sensor is provided on the other unit side that moves the folding portable electronic device when the unit of the portable electronic device is fixed and opened. With portable electronic devices. The portable electronic device with an orientation detection function according to claim 1 or 2, wherein the magnetic sensor is provided at a position distant from the magnetism generation source. When the control means determines that the offset estimation is invalid, the control means performs control for instructing the user to further open or close the foldable portable electronic device. The portable electronic device with an orientation detection function according to any one of claims 1 to 3. When the control means determines that the offset estimation is invalid, the control means performs control for instructing the user to open or close the folding portable electronic device in a plurality of directions. The portable electronic device with an orientation detection function according to any one of claims 1 to 3. A calibration method for azimuth detection means in a folding portable electronic device equipped with azimuth detection means comprising a magnetic sensor and data storage means for storing a plurality of output data of the magnetic sensor ,
Detecting opening and closing of the portable electronic device;
Start storing the output data of the magnetic sensor in the data storage means at the timing of opening or closing the portable electronic device ,
Estimating an offset that is an error in the output of the magnetic sensor based on a plurality of output data stored in the data storage means ,
An offset value used for correcting the output of the magnetic sensor is updated. A calibration method for a portable electronic device with an orientation detection function. A standard deviation calculating means for calculating a standard deviation of the distance on the coordinates of the plurality of output data and the estimated offset;
Effectiveness determination means for determining the effectiveness of the estimated offset based on the calculated standard deviation;
The portable electronic device with an orientation detection function according to any one of claims 1 to 5, further comprising: X orthogonal to each other, Y, detection data of the magnetic sensor having a magnetic sensing direction three axes of Z-axis _{(x i, y i, z} i) (i = 1,2, ..., N) and means for reading,
Define the least square error by [Equation 6],

For [Equation 7] modified from [Equation 6] with a _i = x _i ² + y _i ² + z _i ² , b _i = −2x _i , c _i = −2y _i , d _i = −2z _i ,

The condition [Equation 8] that minimizes the least square error ε is

By solving the equation shown in [Equation 10] using the notation of [Equation 9]

Means for obtaining an offset (X0, Y0, Z0) of the magnetic sensor;
The portable electronic device with an orientation detection function according to claim 1, wherein the portable electronic device has an orientation detection function .

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