JP4586596B2 - Program for correcting portable information terminal and geomagnetic sensor - Google Patents

Description

  The present invention relates to a portable information terminal equipped with a GPS (Global Positioning System) navigation function for displaying a current location, and more particularly to a portable information terminal for correcting an offset of a mounted geomagnetic sensor and a correction program for the geomagnetic sensor.

  2. Description of the Related Art In recent years, a so-called navigation that includes a geomagnetic sensor for detecting geomagnetism, a display screen for displaying a map, and a map DB (Data Base), and performs orientation measurement based on the geomagnetism detected by the geomagnetic sensor. Mobile information terminals such as mobile phones and mobile devices having functions are known. The measured azimuth is used to display a map. As an example, mobile phones having a function of displaying a map based on current position information obtained by a GPS system that performs position detection in accordance with the direction (direction) of the mobile phone have appeared.

  By the way, the conventional geomagnetic sensor is mounted inside a mobile phone together with a speaker and electronic parts. Magnetic fields leaking from such speakers and strong external magnetic fields magnetize metal such as electronic component packages, and there are magnetic fields leaking from this, so the geomagnetic sensor also detects the magnetic fields present inside these mobile phones. End up. Due to the influence of these magnetic fields, the center of the azimuth circle is shifted from the origin. This shift is called offset. If there is such an offset, the azimuth calculated on the assumption that there is no offset based on the measured value of the geomagnetic sensor will be different from the actual azimuth. Therefore, it is necessary to correct the offset from the measured value of the geomagnetic sensor.

  However, the strength and direction of the magnetic field present inside the mobile phone changes due to temperature changes and changes over time, and the above-described offset changes. Therefore, in a mobile phone equipped with a conventional geomagnetic sensor, for example, before use In addition, it is necessary to correct the offset of the geomagnetic sensor. The offset can be corrected based on calibration in which the mobile phone is rotated one or more times while the magnetic sensor is measured.

  Here, a mobile phone equipped with a geomagnetic sensor having two axes in the horizontal plane (X-axis and Y-axis directions) as the sensitivity direction is slowly rotated at a constant speed for one round or more while keeping it horizontal under a certain magnetic field. When the output of the geomagnetic sensor is monitored, a circle is drawn. This circle is called a bearing circle. Such an azimuth circle ideally has a predetermined radius centered at the origin where the X and Y axes intersect.

  The value obtained by subtracting the minimum value from the maximum value of the detection value of each geomagnetic sensor in the X-axis and Y-axis directions and dividing by 2 is used as the sensitivity information of each geomagnetic sensor, and the maximum value and the minimum value are added. Then, the value divided by 2 is used as offset information, and the offset is removed from the detection result of the geomagnetic sensor in the X-axis and Y-axis directions, thereby correcting the measured value of the geomagnetic sensor and using it for the above-described azimuth measurement. The measured value is obtained.

  However, in the mobile phone using the above-described conventional correction method of the geomagnetic sensor, it is necessary to rotate the mobile phone one or more times on the plane in order to obtain the maximum value and the minimum value of the detection value of the geomagnetic sensor. Moreover, if the rotation speed of the mobile phone is too fast, the true maximum and minimum values may not be detected. Conversely, if the rotation speed is too slow, the number of read data becomes enormous and the memory overflows. When the value of the mobile phone is out of a certain range, there is a problem that the accuracy of correction deteriorates or cannot be corrected, and the mobile phone must be rotated while finely adjusting the rotation speed. Further, in the above-described mobile phone, there is a problem that it is difficult to confirm whether the calibration is really successful by rotating the mobile phone from the viewpoint of the user.

  Corresponding to this, for example, Patent Document 1 uses a three-axis (X-axis, Y-axis, Z-axis direction) magnetic sensor, and calibrates the X-axis and Y-axis directions of the magnetic sensor. When the rotation angle around the Z-axis is measured during operation and the rotation angle is distributed between 90 ° and 180 ° or reciprocates between 90 ° and 180 °, An azimuth measuring device that performs measurement by a sensor and corrects the measured value of the magnetic sensor by an offset measured value corrected by the measured value is described. The azimuth measuring device displays the map information on the screen with the direction it is facing upward (heading up) at the start of the calibration operation described above, and the displayed map information is the actual local situation. If the map information does not match, the calibration is performed several times by causing the user to perform the rotation described above until the map information matches the actual local situation. Here, the user stops the calibration when the map information matches the actual local situation.

However, even in the invention according to the publication, in order to perform calibration, the azimuth measuring device is rotated while being held in the hand, as in the past, so that the rotational speed of the azimuth measuring device can be finely adjusted. Cannot be solved.
JP 2004-12416 A

  The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a portable information terminal and a portable information terminal control device capable of correcting an offset of a mounted geomagnetic sensor without rotating the main body. It is intended to provide a correction program for a geomagnetic sensor incorporated in the system.

In order to achieve the above object, the present invention proposes the following means.
The invention according to claim 1 is based on a geomagnetic sensor, position information acquisition means for acquiring position information, map information storage means for storing map information, output of the geomagnetic sensor, the position information, and the map information. If the display means for displaying the map at the current location, the map rotation means for rotating the map to an arbitrary rotation direction and angle, and the map and the landscape of the current location match, according to the rotation direction and angle of the map And a calibration means for updating an offset value of the geomagnetic sensor.

The invention according to claim 2 is a step of displaying a map at the current location on the control computer of the portable information terminal based on the output of the geomagnetic sensor, the position information, and the map information, and rotating the map in an arbitrary rotation direction and angle. And a program for correcting the geomagnetic sensor for executing the step of updating the offset value of the geomagnetic sensor in accordance with the rotation direction and angle of the map when the map and the landscape of the current location match. provide.
According to these inventions, the offset value is calibrated based on the amount of rotation of the map displayed on the portable information terminal instead of rotating the portable information terminal itself as in the prior art.

  According to the present invention, by rotating the map while finely adjusting the rotation speed so as to match the scenery of the current location, the calibration can be performed more easily than when the portable information terminal itself is rotated. There is an effect that can be performed by simple operation. In addition, there is an effect that it is easy to confirm that the calibration is really successful when the map matches the landscape of the current location.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 2, the mobile phone MP includes a casing 1 having operation keys and a casing 2 having liquid crystal display portions on both sides. 2A, the X axis along the short side of the housing 1, the Y axis along the long side of the housing 1, and the thickness direction side of the housing 1 are vertically upward. Assuming a Z-axis extending to The X axis, the Y axis, and the Z axis are orthogonal to each other.

  The casing 1 and the casing 2 are connected to each other through a connecting portion on the short side of each casing, and are configured so that one casing can rotate with respect to the other casing. The body can be folded so as to be overlapped along the thickness direction of the housing.

  Here, each surface of each housing of the mobile phone MP is defined as follows. That is, the surface having the operation keys of the housing 1 is defined as the operation surface, and the surface opposite to the operation surface is defined as the back surface. Of the surfaces of the housing 2, the surface on which the display unit 18a (display means) is provided is the main display surface, and the surface opposite to the main display surface is the front surface.

  The mobile phone MP has a positioning function by GPS and a communication function of a CDMA (Code Division Multiple Access) system.

  In FIG. 1, a mobile phone MP according to the embodiment includes an RF antenna 8, display units 18a and 18b, a microphone 27, a reception sound speaker 28, a geomagnetic sensor module 30 (geomagnetic sensor), and a ring tone speaker. 41, CPU (Central Processing Unit) 101 (display means) (calibration means), ROM (Read Only Memory) 102 (map information storage means), RAM (Random Access Memory) 103, and RF (Radio Frequency) From the transmission / reception unit 104, the key input unit 105, the voice processing unit 107, the GPS reception unit 108 (position information acquisition unit), the sound source unit 109, the GPS antenna 110 (position information acquisition unit), and the bus line 120. Composed. The configuration of the mobile phone MP described above is the same as that of a conventional mobile phone equipped with GPS.

  The RF antenna 8 is connected to the RF transceiver unit 104. The microphone 27 and the reception sound speaker 28 are connected to the sound processing unit 107. A ring tone speaker 41 is connected to the sound source unit 109. The GPS antenna 110 is connected to the GPS receiving unit 108.

  The RF antenna 8 transmits and receives radio waves with a radio base station (not shown). The RF transmitter / receiver 104 performs processing related to signal transmission / reception. The RF transmitter / receiver 104 includes a local oscillator or the like, and mixes a received signal output from the RF antenna 8 at the time of reception with a locally transmitted signal having a predetermined frequency, thereby converting the received signal to an intermediate frequency (IF). The received IF signal is output to an internal modulation / demodulation unit. The modem unit converts the received IF signal into a baseband signal having a predetermined frequency, converts the baseband signal into a digital signal, and outputs the digital signal to the internal CDMA unit. The CDMA unit decodes the received signal and decodes the baseband signal output from the modem unit.

  Also, the CDMA unit in the RF transceiver unit 104 encodes a transmission signal, converts it into a baseband signal, and outputs it to the modem unit. The modem unit transmits the digital baseband for transmission output from the CDMA unit. By modulating the signal of the IF frequency with the signal, the signal is converted into an analog signal, further converted into an RF signal, and the RF signal is output to the RF antenna 8.

  The voice processing unit 107 performs processing related to voice during a call. The audio processing unit 107 converts an analog audio signal output from the microphone 27 during a call into a digital signal, and outputs the digital signal to the CDMA unit in the RF transmission / reception unit 104 as a transmission signal. In addition, the voice processing unit 107 generates an analog drive signal for driving the ring tone speaker 28 based on a signal indicating the voice data decoded by the CDMA unit in the RF transmission / reception unit 104 during a call. Output to the ring tone speaker 28. The microphone 27 generates an audio signal based on the audio input by the user and outputs the audio signal to the audio processing unit 107. The ring tone speaker 28 generates the voice of the other party on the basis of the signal output from the voice processing unit 107.

  The GPS antenna 110 receives a radio wave transmitted from a GPS satellite and outputs a reception signal based on the radio wave to the GPS receiving unit 108. The GPS receiver 108 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 108 calculates a distance to three or more GPS satellites based on the acquired information, and calculates a position (latitude, longitude, altitude, etc.) (position information) in a three-dimensional space based on the principle of triangulation. To do.

  The CPU 101 controls each part inside the mobile phone MP. The CPU 101 includes control signals or data via the RF transmission / reception unit 104, the audio processing unit 107, the GPS reception unit 108, the geomagnetic sensor module 30, the ROM 102, the RAM 103, the key input unit 105 and the display units 18 a and 18 b, and the bus line 120. I / O is performed.

  The ROM 102 stores various programs executed by the CPU 101. In addition, the initial characteristic value of the geomagnetic sensor module 30 measured at the time of shipping inspection is stored. Further, offset reference data serving as a reference for whether or not offset correction is necessary in actual use is stored. The offset reference data refers to the radius of the output azimuth circle measured by the geomagnetic sensor module 30 measured at the time of shipping inspection, and includes an initial offset value and a geomagnetic intensity. The ROM 102 has an area as a map data DB, and stores map information in the area.

  The RAM 103 temporarily stores data processed by the CPU 101. The RAM 103 also stores offset measurement values and measurement data of the geomagnetic sensor module 30 as will be described later.

  The sound source unit 109 includes a ring tone speaker 41 and notifies the user of an incoming call or mail reception by sound. Also, the musical sound generated from the content data downloaded from the content server is reproduced. Note that the ring tone speaker 41 is provided on the back surface of the housing 1 as shown in FIG.

  As shown in FIG. 2A, the key input unit 105 includes a start key 3 used when receiving a call, an end key 4 used when ending a call or turning on / off a power, a numeric key, A numeric keypad 5 including a code key, a redial key 7, cursor keys 9a and 9b (map rotating means), 9c and 9d for operating the cursor, and a confirmation button 10 used for confirming an operation instruction by operating each key A conversion key 11 for conversion of kanji and numbers, etc., and a signal indicating an operation result by the user is output to the CPU 101.

  Each of the cursor keys 9a and 9b is assigned a function of rotating the map MAPa displayed on the display unit 18a to the left and right, and the map MAPa is rotated by a certain angle when pressed once. Thus, the map MAPa rotates only when the cursor key 9a or 9b is pressed, and the map MAPa stops rotating when the cursor key 9a or 9b is released (no longer pressed).

  The display units 18a and 18b are configured by a liquid crystal display, and display text information of text created when an e-mail is transmitted, various data including contents of various menus, and detailed contents thereof. It is like that. The display unit 18 a is provided on the main display surface of the housing 2, and the liquid crystal display unit 18 b is provided on the front surface of the housing 2.

  The geomagnetic sensor module 30 is configured as shown in FIG. 3 and is set on the same horizontal plane and detects the geomagnetism (magnetic field) in the axial direction (magnetic sensitive direction) of each of the X axis and Y axis orthogonal to each other. Magnetic sensors 31, 32 comprising GMR (Giant Magnetoresistive) elements, a switch 33 for selectively outputting the detection output signal Sx or Sy (direction information) of the magnetic sensors 31, 32, and an output signal of the switch 33 Amplifier 34, an A / D converter 35 that performs A / D (Analog / Digital) conversion of the output signal of the amplifier 34, and an I for outputting the output signal of the A / D converter 35 to the outside of the geomagnetic sensor module 30. / F (interface) unit 36. As shown in FIG. 2A, the geomagnetic sensor module 30 is arranged in the center of the housing 1 so that the magnetic sensing directions of the magnetic sensors 31 and 32 are parallel to the X axis and the Y axis, respectively. It is attached to the part. Thereby, the magnetic sensing direction of the geomagnetic sensor module 30 becomes the X axis and the Y axis. Although the two-axis geomagnetic sensor module 30 has been described above, when a three-axis geomagnetic sensor module is required, the Z axis is set perpendicular to the X axis and the Y axis, and the Z axis direction is Add a magnetic sensor for the direction of magnetic sensing.

  The magnetic sensors 31 and 32 output detection output signals Sx and Sy corresponding to the geomagnetism strength in the X-axis direction and the Y-axis direction. The switch 33 selectively outputs the detection output signals Sx and Sy of the magnetic sensors 31 and 32 to the input terminal of the amplifier 34. The amplifier 34 amplifies the detection output signal Sx or Sy of the magnetic sensor 31 or 32 output from the switch 33 and outputs it to the A / D converter 35. The A / D converter 35 digitizes the detection output signal Sx or Sy and outputs it to the bus line 120 via the I / F (interface) unit 36.

  Next, the principle of the direction measuring method of the mobile phone MP will be described. In the present embodiment, description will be made assuming that the operation surface of the mobile phone MP is placed in a substantially horizontal state and the external magnetic field applied to the geomagnetic sensor module 30 is only geomagnetism. Here, the azimuth ang of the mobile phone MP refers to the front portion of the operation surface of the mobile phone MP shown in FIG. 2A (for example, the microphone 27) when the operation surface of the housing 1 of the mobile phone MP is substantially horizontal. ) To the center of the connecting portion, that is, the direction of the vector toward the positive direction of the Y axis. Further, when the detection output signals Sx and Sy described above are plotted on a graph in which the X axis, the Y axis are the horizontal axis, and the vertical axis, respectively, an azimuth circle as shown in FIG. 4 is drawn.

  At this time, when the upward direction (Y-axis direction) of the mobile phone MP is obtained, the reference (0 °) of the direction ang is north, and the same direction ang rotates in the order of east, south, and west. They are 90 °, 180 ° and 270 °, respectively. The intermediate direction is also obtained from each output value.

  By the way, geomagnetism is a magnetic field from south to north. Therefore, when the operation surface of the casing 1 of the mobile phone MP is substantially horizontal, the outputs of the magnetic sensor 31 in the X-axis direction and the magnetic sensor 32 in the Y-axis direction of the geomagnetic sensor module 30 are cosine and sine waves. Each changes.

From the above, the azimuth ang of the mobile phone MP can be obtained in the following cases (a) to (d).
(A) For Sx and Sy, when Sx> 0 and | Sx |> | Sy | are satisfied, the azimuth ang = tan ⁻¹ (Sy / Sx).
(B) When Sx <0 and | Sx |> | Sy | are satisfied, ang = 180 ° + tan ⁻¹ (Sy / Sx).
(C) When Sy> 0 and | Sx | <| Sy | are satisfied, ang = 90 ° -tan ⁻¹ (Sx / Sy).
(D) When Sy <0 and | Sx | <| Sy | are satisfied, ang = 270 ° −tan ⁻¹ (Sx / Sy).
However, when the azimuth ang obtained by any one of the above (a) to (d) is negative, a value obtained by adding 360 ° to the same azimuth ang is defined as the azimuth ang. Further, when the obtained azimuth ang is 360 ° or more, a value obtained by subtracting 360 ° from the same azimuth a is set as the azimuth ang.

  However, as described above, the mobile phone MP includes many permanent magnet parts as represented by the incoming speaker 28, and a magnetic field leaks from these parts. Therefore, a leakage magnetic field (external magnetic field other than geomagnetism) due to these permanent magnet components is applied to the geomagnetic sensor module 30 disposed at a predetermined location in the mobile phone MP. As a result, the output of the magnetic sensor 31 in the X-axis direction is shifted (translated) by an output corresponding to the X-axis component of the leakage magnetic field. Similarly, the output of the magnetic sensor 32 in the Y-axis direction is Y of the leakage magnetic field. An offset corresponding to the axis component is shifted (offset), and each shifted output is referred to as an “offset measurement value”. Therefore, in order to measure an accurate azimuth in the mobile phone MP, it is necessary to correct the measurement value by removing the offset by calculation such as subtracting the offset measurement value described above from the measurement value.

  Next, the offset calibration operation of the geomagnetic sensor module 30 of the mobile phone MP according to the present embodiment will be described. Offset calibration refers to measuring external magnetism for obtaining an offset measurement value.

  Here, as shown in FIG. 5, the user Hu faces in the direction of the street STR, and holds the mobile phone MP in the embodiment of the present invention straight in the direction of the street STR while keeping the casing 1 horizontal. Assume that you are standing with you.

  First, the power of the mobile phone MP is turned on, and the operation of the mobile phone MP is started. Hereinafter, the offset calibration operation of the geomagnetic sensor module 30 of the mobile phone MP will be described with reference to the flowcharts shown in FIGS. 5 and 6 to 7 and FIGS.

  First, a calibration start button (trigger key, not shown) for instructing offset calibration is pressed. Next, the CPU 101 receives GPS data from the GPS receiving unit 108, acquires current position information from the GPS data, and obtains the current direction information from the geomagnetic sensor module 30 based on the above-described principle of direction measurement of the mobile phone MP. Based on the acquired position information and orientation information, the map MAPa is displayed on the display unit 18a as shown in FIG. 8A (step Sp1). At this time, in the display unit 18a, the current position PP that is the position of the user Hu carrying the mobile phone MP and the arrow AR indicating the direction that is the reference of the azimuth ang of the mobile phone MP are on the map MAPa. Is displayed.

  Next, it is determined whether or not any of the cursor keys 9a or 9b which is a left / right rotation button has been pressed (step Sp2). If the determination is “NO”, the map MAPa does not rotate, the process returns to step Sp1, and the following steps Sp1 to Sp2 are repeated.

On the other hand, if the determination in step Sp2 is “YES”, the process proceeds to step Sp3. For example, when the cursor key 9a is pressed, the entire map MAPa rotates leftward about the current position PP.
The cursor key 9b has a function of rotating the map MAPa in the right direction, contrary to the cursor key 9a. This facilitates the operation of passing through the arrow AR and parallel to the STR road. Further, the rotation speed of the map MAPa when the cursor key 9a or 9b is pressed may be selected. For example, when the user selects a slow rotation speed when the arrow AR and the STR road approach in parallel, the user can accurately adjust the speed.

  Then, as shown in FIG. 8 (b), the user confirms that the arrow AR and the street STR road are parallel, the map MAPa and the current landscape match, and the cursor key 9a is released. Then, it is determined whether or not the confirmation button 10 has been pressed (step Sp4). If the determination is “NO”, the process returns to step Sp3, and the following operations in steps Sp3 to Sp4 are repeated.

  On the other hand, if the determination in step Sp4 is “YES”, the process proceeds to step Sp5, and a temporary offset value is calculated from the direction and angle in which the map is rotated. With the above operation, a temporary offset value is calculated from the amount of rotation of the map MAPa.

  Here, details of the offset calibration operation of the geomagnetic sensor module 30 of the mobile phone MP in Step Sp5 will be described with reference to FIGS. At this time, it is assumed that the map MAPa is inclined by an angle α ° as compared to the landscape of the current location, and the map MAPa is rotated by the angle α ° and transferred to the map MAPb.

  At this time, FIG. 9A shows a point P1 'actually measured when the point P1 indicated by the arrow is measured from the mobile phone MP placed at the point O which is the origin. As described above, since the map MAPa is tilted by the angle α ° compared to the current location on the display unit 18a of the mobile phone MP, the straight line OP1 that is an extension of the arrow in the figure is By measuring the magnetic data near the intersection of the straight line (dotted line) OP1 ′ forming the angle α ° and the azimuth circle, the point P1 ′ is actually measured. Therefore, as shown in FIG. 9B, the actual origin O 'is somewhere on the straight line P1'P1' '(dashed line) parallel to the straight line OP1 and passing through the point P1'. There will be. As a result, although the Y-axis component is not fixed, the actual origin O ′ where the X-axis component is fixed is obtained. Here, the vector from the origin O to the actual origin O ′ becomes a temporary offset value, and the offset value stored in the RAM 103 is updated by the offset value.

  As described above, since the Y axis component of the actual origin O ′ has not been determined, the Y axis component of the actual origin O ′ is determined by the following procedure.

  That is, as shown in FIG. 9C, the intersection point of the perpendicular line drawn from the current origin O to the straight line P1'P1 '' is set as the new origin O '. Then, the position of the cellular phone MP is moved from the origin O to the new origin O ′, and the cellular phone MP is directed in the direction indicated by the same angle as described above or by an angle other than the azimuth difference of 180 °. At this time, since the origin O ′ is a provisional origin where the Y-axis component is not determined, the map MAPb is tilted compared to the landscape of the current location. Therefore, it is assumed that the map MAPb is rotated by an angle β ° so that the map MAPb matches the landscape of the current location.

  Next, as in step Sp1, the CPU 101 receives GPS data from the GPS receiving unit 108, acquires current position information from the GPS data, acquires current direction information from the geomagnetic sensor module 30, and acquires the acquired position. Based on the information and the orientation information, a map is displayed on the display unit 18a (step Sp6). At this time, on the display unit 18a, the current position PP, which is the position where the user Hu carrying the mobile phone MP is present, and an arrow AR indicating the direction that is the reference for the azimuth ang of the mobile phone MP are displayed on the map. Is displayed.

  Next, as in step Sp2, it is determined whether or not any of the cursor keys 9a or 9b, which are left and right rotation buttons, has been pressed (step Sp7). If the determination is “NO”, the map does not rotate, the process returns to Step Sp6, and the following Steps Sp6 to Sp7 are repeated.

  On the other hand, if the determination in step Sp7 is “YES”, the process proceeds to step Sp8 and the entire map rotates. Then, as in step Sp4, the user confirms that the arrow AR and the street STR road are parallel, the map and the current landscape match, the cursor key 9a or 9b is released, and the confirmation button It is determined whether or not 10 has been pressed (step Sp9). If the determination is “NO”, the process returns to step Sp8, and the following operations in steps Sp8 to Sp9 are repeated.

  On the other hand, if the determination in step Sp9 is “YES”, the process proceeds to step Sp10, and a formal offset value is calculated from the direction and angle in which the map is rotated. With the above operation, a formal offset value is calculated from the amount of rotation of the map MAPa.

  Here, details of the offset calibration operation of the geomagnetic sensor module 30 of the mobile phone MP in step Sp10 will be described with reference to FIG. At this time, it is assumed that the map is inclined by an angle β ° compared to the landscape of the current location, and the map is rotated by an angle β °.

  At this time, FIG. 9D shows a point P2 'that is actually measured when the point P2 indicated by the arrow is measured from the mobile phone MP placed at the point O' that is the origin. As described above, since the map MAPa is tilted by an angle β ° as compared with the scenery of the current location on the display unit 18a of the mobile phone MP, the straight line O ′, which is an extension of the arrow in the figure. This means that magnetic data in the vicinity of the intersection of the straight line (dotted line) O′P2 ′ that forms an angle β ° with P2 and the azimuth circle is measured. Similarly to the matter shown in FIG. 9B, as shown in FIG. 9D, a straight line P2′P2 ″ (dotted line) parallel to the straight line O′P2 and passing through the point P2 ′. A perpendicular line is drawn from the origin O ′, and the intersection of the perpendicular line and the straight line P2′P2 ″ is the final origin origin O ″. As a result, the Y-axis component is also determined, and the actual origin O ″ is obtained. Then, the vector from the origin O to the final origin O ″ becomes a formal offset value, and the temporary offset value stored in the RAM 103 is updated by the offset value.

  Next, based on the updated offset value, the CPU 101 receives GPS data from the GPS receiving unit 108 and acquires current position information from the GPS data, as in Steps Sp1 and Sp6, and from the geomagnetic sensor module 30. Current azimuth information is acquired, and a map is displayed on the display unit 18a based on the acquired position information and azimuth information (step Sp11). Then, the offset calibration operation of the geomagnetic sensor module 30 of the mobile phone MP ends.

  As described above, according to the present embodiment, by pressing the cursor key 9a or 9b while the mobile phone MP is fixed in the hand, the mobile phone MP is tilted by a certain angle as compared to the landscape of the current location due to the influence of the offset. The map MAPa is rotated while finely adjusting the rotation speed so as to match the landscape of the current location, the offset value is calculated from the rotation amount, and the offset value stored in the RAM 103 is updated with the offset value. It becomes possible. Therefore, the calibration can be performed by a simple operation as compared with the conventional calibration of offset by rotating the mobile phone MP itself.

  Further, in the present embodiment, after the calibration is completed, the map MAPb that matches the landscape of the current location is displayed on the display unit 18a of the mobile phone MP. By doing so, it is possible to visually confirm whether the calibration is really successful.

  Here, even in the case of using navigation, it seems that the orientation at the place is often recognized depending on the positional relationship of the building or the like as a guide. For example, the mobile phone MP is parallel to the road (for example, The appropriate position of the geomagnetic sensor module 30 is obtained by using the information on the accurate direction of the building and the like by aligning the landscape of the current location with the casings 1 and 2 of the mobile phone MP. Since the calibration can be performed, the present invention is effective.

In the present embodiment, the GMR element is assumed as the geomagnetic sensor, but the type of the geomagnetic sensor is not limited to this, and a magnetoresistive effect element such as a TMR (Tunneling Magnetoresistive) element, MR (Magnetoresistive) element, Any element such as a Hall element, an MI (Magneto Impedance) element, or a fluxgate sensor may be used.
In particular, an element such as a Hall element that has a severe temperature change can be used to correct an offset change due to temperature. An element that is easily magnetized, such as an MI element, is effective as means for removing the influence of the element itself.

  In the present embodiment, the map MAPa is rotated by a certain angle by one press of the cursor key 9a or 9b. As a result, the map MAPa is only pressed when the cursor key 9a or 9b is pressed. Rotate the map and stop the MAPA rotation when the cursor key 9a or 9b is not pressed. However, the map MAPa is automatically rotated to match the map MAPa and the current landscape as follows. You may let them. That is, in the control program of the CPU 101, the adjustment mode is supported, and the mode is shifted to the adjustment mode by a specific key operation. When the cursor key 9a or 9b is pressed, the map MAPa is automatically rotated, and the map MAPa becomes the current location. The map MAPa may be stopped by pressing the confirmation button 10 when it matches the landscape. As a result, any method may be used as long as the map MAPa and the scenery of the current location can be matched.

  Further, in the present embodiment, the offset value is determined by two map corrections by the processing of steps Sp1 to Sp5 and the processing of steps Sp6 to Sp10 in the flowcharts shown in FIGS. Depending on the scale of the map displayed on the display unit 18a of the mobile phone MP, the request for the accuracy of the offset value may not be high. Even if the temporary offset value obtained by the processing of Steps Sp1 to Sp5 is used as it is. Good. Further, by repeating the processing of steps Sp6 to Sp10, the map correction may be performed three times or more to further increase the accuracy of the offset value.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the specific structure is not restricted to this embodiment, The design change in the range which does not deviate from the summary of this invention is also included.

It is a block diagram which shows the structure of mobile telephone MP in one Embodiment of this invention. 2 is a diagram illustrating an appearance of a mobile phone MP in the same embodiment. FIG. It is a block diagram which shows the structure of the geomagnetic sensor module 30 in the embodiment. It is a figure which shows the azimuth | direction circle drawn by the detection output signals Sx and Sy in the geomagnetic sensor module 30. FIG. It is a figure which shows the situation at the time of calibrating mobile telephone MP in the embodiment. 7 is a flowchart showing a calibration operation in the mobile phone MP in the same embodiment. 7 is a flowchart showing a calibration operation in the mobile phone MP in the same embodiment. It is a figure which shows a mode that an offset is measured by map MAPa and arrow AR which are displayed on the display part 18a of the mobile telephone MP in the embodiment. It is a figure which shows the detail of the operation | movement of offset calibration of the geomagnetic sensor module 30 of the mobile telephone MP in the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 ... Case, 3 ... Start key, 4 ... End key, 5 ... Numeric keypad, 7 ... Redial key, 8 ... RF (Radio Frequency) antenna, 9a, 9b ... Cursor keys (map rotation means), 9c, 9d ... Cursor keys, 10 ... Confirm button, 11 ... Conversion key, 18a ... Display section (display means), 18b ... Display 27, microphone, 28 reception speaker, 30 ... geomagnetic sensor module (geomagnetic sensor), 31, 32 ... magnetic sensor, 33 ... switch, 34 ... amplifier , 35..., A / D (Analog / Digital) converter, 36... I / F (interface) section, 41 .. ring tone speaker, 101... CPU (Central Processing Unit) (display means) ) (Calibration means), 102... R M (Read Only Memory) (map information storage means), 103... RAM (Random Access Memory), 104... RF (Radio Frequency) transmission / reception unit, 105... Key input unit, 107. , 108 ... GPS (Global Positioning System) receiving part (position information acquisition means), 109 ... sound source part, 110 ... GPS antenna (position information acquisition means), 120 ... bus line, AR ...・ Arrow, Hu ... User, MAPa, MAPb ... Map, MP ... Mobile phone, PP ... Current position, STR ... Street

Claims (2)

A geomagnetic sensor,
Position information acquisition means for acquiring position information;
Map information storage means for storing map information;
Display means for displaying a map of the current location based on the output of the geomagnetic sensor and the position information and the map information;
Map rotation means for rotating the map in an arbitrary rotation direction and angle;
When the map and the landscape of the current location match, calibration means for updating the offset value of the geomagnetic sensor according to the rotation direction and angle of the map;
A portable information terminal comprising: To the control computer of the portable information terminal,
Displaying a map of the current location based on the output and position information of the geomagnetic sensor and map information;
Rotating the map in an arbitrary rotation direction and angle;
When the landscape of the map and the current location match, updating the offset value of the geomagnetic sensor according to the rotation direction and angle of the map;
Program for correcting the geomagnetic sensor to execute

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