CN1957228A - Mobile bearing calculation device and bearing correction method - Google Patents

Abstract

A mobile map display device has a terrestrial magnetism sensor for measuring terrestrial magnetism, a display section, and a control section capable of calculating a geographical bearing based on the value measured by the terrestrial magnetism sensor and having first display processing and second processing where, when the control section obtains a map and makes it displayed on the display section, the first display processing causes the map to be displayed in a direction associated with the calculated bearing and the second display processing causes the map to be displayed in a manner fixed in a predetermined bearing. In displaying the map, upon detecting deterioration in the accuracy of the terrestrial magnetism sensor, the control section causes the map to be displayed by the second display processing.

Description

Mobile orientation calculation device and orientation correction method

technical field

The invention relates to a mobile communication device, such as a mobile phone, provided with a geomagnetic sensor for measuring a geographical position, and a method for calibrating the geomagnetic sensor.

Background technique

Usually, a device is needed to confirm the geographic location of the current location and provide directions to the destination location through a map. As an apparatus meeting such a demand, a car navigation system is known (for example, Patent Document 1, Patent Document 2, and Patent Document 3).

In general, a car navigation system calculates the geographic position of a current location by receiving and processing signals transmitted from a plurality of GPS (Global Positioning System) satellites (hereinafter referred to as "GPS signals"), from a storage unit (DVD , hard disk, etc.) read out the map data about the current location environment and display it on the display. In addition, by using a vehicle speed sensor and a gyro sensor to calculate the moving path of the vehicle, map matching processing is performed to detect the degree of coincidence between the moving path and the road on the map, and to correct positioning errors.

However, there is a need for the user to determine his or her own location and know the route to a destination even when not in the vehicle. As a device meeting such a demand, a mobile cellular phone equipped with a simple map information display processing function has appeared.

Initially, mobile cellular phones equipped with a map information display processing function lacked a device for measuring the orientation, so it was difficult to realize a map display that is easy for the user to understand, such as the heading up display (displaying a rotating map, so that the forward direction points to the top of the screen).

Therefore, in recent years, there have been proposed mobile cellular phones provided with a map information display processing function to measure an azimuth by using a geomagnetic sensor, and to realize heading-up display.

Patent Document 1: Japanese Patent Laid-Open (A) No. 2004-28837

Patent Document 2: Japanese Patent Laid-Open (A) No. 2002-328042

Patent Document 3: Japanese Patent Laid-Open (A) No. 10-197258

Contents of the invention

The problem to be solved by the present invention

However, geomagnetic sensors that detect extremely weak geomagnetism are affected by magnetic fields generated by various components in mobile cellular phones or other communication devices, and are prone to errors. In particular, recent mobile and portable cellular phones have become smaller in size. It becomes more difficult to ensure a sufficient distance between components. Therefore, geomagnetic detection errors due to magnetic fields generated by components in communication equipment have become non-negligible. For this reason, for example, in a mobile cellular phone to which a memory card can be attached/detached and configured to allow read/write operations, there is a problem that the state with the memory card loaded differs from the state without the memory card loaded. Bearing calculation results differ between states.

On the other hand, in recent mobile and portable cellular phones with large display screens, many devices appear in the form of a display unit and a key input unit provided in different casings. This type of cellular phone is usually used in a state where two housings are folded to overlap each other and a key input unit is hidden inside the housing (closed state), or in a state where both the key input unit and display unit are exposed (open state).

Such a double housing type cellular phone includes a type in which the display unit is hidden inside the housing in a closed state and a type in which the display unit is exposed to the outside of the housing. Representative examples of the latter type include a type in which the display unit surface and the key input unit surface rotate relative to each other in an almost parallel state.

Thus, in a cellular phone in which the display unit can be used in both the open state and the closed state, it is desirable to use the map information display processing function in both states. However, when the open/closed state of the casing is changed, the magnetic field around the geomagnetic sensor changes, so there is a problem that it is difficult to obtain azimuth measurement results.

Also, in mobile cellular phones, due to size and cost constraints, it is difficult to correct azimuth measurement errors by using detection methods other than geomagnetic sensors, such as gyro sensors used in car navigation systems to detect the direction of motion.

The present invention has been made in consideration of these circumstances, and an object of the present invention is to provide a mobile azimuth calculation device capable of finding an azimuth with high precision by using a geomagnetic sensor and capable of determining the Correct geographic orientation.

Another object of the present invention is to provide an azimuth correcting method capable of finding an azimuth with high precision by using a geomagnetic sensor and capable of correcting a geographical azimuth according to an event of an operation change of an installed electronic part.

means of solving problems

According to the present invention, there is provided a mobile azimuth calculation device having a geomagnetic sensor for detecting geomagnetism and a control unit for calculating a geographic azimuth based on the detection value of the geomagnetic sensor, wherein the control unit monitors the An event in which the operation of an electronic component changes, and the geographic orientation is corrected based on the occurrence of the event.

In addition, according to the present invention, there is provided an azimuth correction method in a mobile azimuth calculation device, the mobile azimuth calculation device has a geomagnetic sensor for detecting geomagnetism, and calculates the geographic azimuth based on the detection value of the geomagnetic sensor, the The method includes the steps of monitoring for events causing changes in the operation of electronic components installed in the mobile position computing device, and the steps of correcting the geographic position based on the occurrence of the event.

Effect of the present invention

According to the present invention, it is possible to use a geomagnetic sensor to determine the orientation with high precision, and to correct the geographic orientation according to an event causing a change in the operation of the installed electronic parts.

Description of drawings

1 is a block diagram showing a configuration example of a system for acquiring geographic location and map information in a mobile cellular phone according to an embodiment of the present invention;

Figure 2 is a perspective view of the mobile cellular phone in an open state;

Figure 3 is a perspective view viewed from one side of the mobile cellular phone in a closed state;

Figure 4 is a perspective view viewed from another side of the mobile cellular phone in a closed state;

5 is a perspective view showing a circuit board mounting state inside the circuit board mounting case;

6 is a block diagram showing a configuration example of a mobile cellular phone according to an embodiment of the present invention;

7 is a flowchart illustrating an example of GPS signal reception processing in a mobile cellular phone;

FIG. 8 is a flowchart illustrating an example of place discovery processing in a mobile cellular phone;

FIG. 9 is a diagram showing an example of map information transmitted from a navigation server system;

10 is a flowchart illustrating an example of rotation processing of a display image in a mobile cellular phone;

FIG. 11 is a diagram for explaining an azimuth calculation method;

Fig. 12 is a flowchart illustrating a first example of azimuth calculation processing in a mobile cellular phone;

FIG. 13 is a diagram showing an example of correction data;

14 is a flow chart illustrating a second example of azimuth calculation processing in a mobile cellular phone;

15 is a flowchart illustrating a third example of azimuth calculation processing in a mobile cellular phone;

16 is a flowchart illustrating a fourth example of azimuth calculation processing in a mobile cellular phone;

17 is a flowchart illustrating a fifth example of azimuth calculation processing in a mobile cellular phone;

FIG. 18 is a graph showing an example of a change over time of a geomagnetic sensor detection value according to memory card loading;

19 is a flowchart illustrating a sixth example of azimuth calculation processing in a mobile cellular phone;

20 is a flowchart illustrating a first example of offset error correction processing when a geomagnetic detection value occurrence abnormal state occurs;

Fig. 21 is a diagram showing an example of an abnormal state of a geomagnetic detection value due to the influence of an external magnetic field;

22 is a flowchart illustrating a second example of offset error correction processing in a mobile cellular phone;

23 is a flowchart illustrating a third example of offset error correction processing in a mobile cellular phone;

24 is a flowchart illustrating a first example of processing when an error occurs in a geomagnetic detection value due to the influence of an external magnetic field;

25 is a flowchart illustrating a second example of processing when an error occurs in a geomagnetic detection value due to the influence of an external magnetic field;

26 is a flowchart illustrating a third example of processing when an error occurs in a geomagnetic detection value due to the influence of an external magnetic field;

27 is a flowchart illustrating a fourth example of processing when an error occurs in a geomagnetism detection value due to the influence of an external magnetic field;

28 is a flowchart illustrating a fifth example of processing when an error occurs in a geomagnetism detection value due to the influence of an external magnetic field;

29 is a flowchart illustrating a sixth example of processing when an error occurs in a geomagnetism detection value due to the influence of an external magnetic field;

30 is a flowchart illustrating a seventh example of processing when an error occurs in a geomagnetism detection value due to the influence of an external magnetic field;

31 is a flowchart illustrating an eighth example of processing when an error occurs in a geomagnetic detection value due to the influence of an external magnetic field; and

FIG. 32 is a flowchart illustrating a processing example of registering a precision-reduced area in a storage unit in the processing shown in FIGS. 28 to 31 .

Label description

2...first housing, 3...second housing, 4...move mechanism, 21...display panel, 100...mobile cellular phone, 200...GPS satellite, 300...base station , 401...GPS server system, 402...Navigation server system, 150...Wireless communication unit, 151...GPS signal receiver, 152...Storage unit, 153...Open/close state judgment unit, 154...key input unit, 155...audio processing unit, 157...image capture unit, 158...geomagnetic sensor, 159...memory card unit, 160...control unit.

Detailed ways

When the present invention is applied to a multifunctional type movable, portable cellular phone (hereinafter referred to as "mobile cellular phone") having a map information display processing function and an image capture function and capable of displaying map information in consideration of the orientation, the following will be explained with reference to the drawings. the embodiment.

FIG. 1 is a block diagram showing a configuration example of a system for acquiring geographic location and map information in a cellular phone 100 according to an embodiment of the present invention.

The cellular phone 100 receives GPS signals transmitted from three or more GPS satellites 200 orbiting the earth in known orbits. Then, the cellular phone 100 transmits information on the received GPS signal from the base station 300 to the GPS server system 401 (as an example of the spot finding device of the present invention) through the communication network, and acquires the position of the current spot from the GPS server system 401 information.

In addition, the cellular phone 100 transmits the position information of the current spot acquired from the GPS server system 401 from the base station 300 to the navigation server system 402 (as an example of the spot finding device of the present invention) through the communication network, and acquires from the navigation server system 402 Map information about the environment of the current location.

The GPS server system 401 (as an example of the spot finding device of the present invention) calculates a geographical position (e.g., latitude and longitude) from the GPS signal transmitted from the cellular phone 100 through the communication network, and transmits the calculated position information through the communication network and the base station. 300 is sent to cellular phone 100.

The navigation server system 402 (as an example of the spot finding device of the present invention) retrieves map information about the environment of the cellular phone 100 from a database (not shown) based on the map information transmitted from the cellular phone 100 through the communication network, and retrieves The received map information is transmitted to the cellular phone 100 through the communication network and the base station 300 .

2 to 4 are diagrams showing examples of the appearance of the cellular phone 100 .

2 is a perspective view of cellular phone 100 in an open state, FIG. 3 is a perspective view of cellular phone 100 in a closed state from one side, and FIG. 4 is a perspective view of cellular phone 100 in a closed state from another side.

In the cellular phone 100, a first housing (upper housing 2) and a second housing (lower housing) 3 are connected by a movable mechanism unit 4 so that they can be freely opened/closed and/or freely rotated.

The movable mechanism unit 4 is configured such that the first casing 2 and the second casing 3 can be relatively rotated around a predetermined rotation axis and/or opened/closed.

In the first casing 2, the first surface 2a that is exposed regardless of the operating state (open state, closed state) of the movable mechanism unit 4 has a structure composed of, for example, an LCD (Liquid Crystal Display) panel or an organic EL (Electroluminescence) display panel. The display panel 21. A speaker 22 is built in the left corner of the display panel 21 in FIG. 2 .

The display panel 21 is included in a display unit 155 explained later. The speaker 22 is included in the audio processing unit 156 explained later.

The second case 3 is formed by overlapping a circuit board mounting case 31 in which a circuit board is mounted and a cover side case 32 forming a cover of the circuit board mounting case 31 .

On the outer flat surface 31a of the circuit board mounting case 31 of the second case 3, that is, on the surface 31a facing one surface of the first case 2 in the closed state, there are arrays including numeric key buttons 311a, cursor buttons 311b and The operation key 311 of the enter key 311c. At the right corner in FIG. 2 of the operation key 311, a microphone 312 is built-in.

The operation keys 311 are included in the key input unit 154 explained later. The microphone 312 is included in the audio processing unit 156 explained later.

On the outer flat surface 32a (exposed regardless of the open state or the closed state) of the cover case side case 32 of the second case 3, as shown in FIG. 4, an optical system 34a of the camera module 34 is provided.

On the outer flat surface 32a of the cover side housing 32 of the second housing 3, a light emitting window 321 for emitting a flash to the outside through a built-in flash and a light emitting window 321 for emitting white light to facilitate image capture when taking a photo are provided. window322.

The camera module 34 is included in an image capturing unit 157 explained later.

A camera module tack switch 35 is provided on one side of the second housing 3 , and a memory card slot 33 for inserting a memory card is formed on the other side of the second housing 3 .

FIG. 5 is a perspective view showing a circuit board mounting state in the interior 31 b of the circuit board mounting case 31 .

In the interior 31b of the circuit board mounting case 31, a main board 37 is mounted on the bottom surface thereof.

At a position facing the memory card slot 33 on the main board 37, a memory card unit 159 to which a detachable memory card can be connected is mounted.

At a substantially central position adjacent to the memory card unit 159 on the main board 37, a geomagnetic sensor 158 is mounted.

FIG. 6 is a block diagram showing an illustrative example of the configuration of the cellular phone 100 according to the embodiment of the present invention.

The cellular phone 100 has a wireless communication unit 150, a GPS signal receiver 151, a storage unit 152, an opening/closing determination unit 153, a key input unit 154, a display unit 155, an audio input/output unit 156, an image capturing unit 157, a geomagnetic sensor 158 , a memory card unit 159 and a signal processing/control unit 160.

The wireless communication unit 150 is an embodiment of the wireless communication device of the present invention.

The GPS signal receiver 151 is an embodiment of the GPS signal receiving device of the present invention.

The GPS signal receiver 151 and the wireless communication unit 150 are embodiments of the location information acquiring means of the present invention.

The opening/closing judging unit 153 is an embodiment of the operation state judging means of the present invention.

The display unit 155 is an example of a display device of the present invention.

The geomagnetic sensor 158 is an embodiment of the geomagnetic sensor of the present invention.

The memory card unit 159 is an embodiment of a storage medium mounting device of the present invention.

The signal processing/control unit 160 is an embodiment of the signal processing/control means of the present invention.

The wireless communication unit 150 performs processing related to wireless communication with the base station 150 in cooperation with the signal processing/control unit 160 . For example, the wireless communication unit 150 applies predetermined modulation processing to the transmission data output from the signal processing/control unit 160 to convert it into a wireless signal, and transmits it from the first antenna AT1. In addition, the wireless communication unit 150 applies predetermined demodulation processing to the wireless signal received at the first antenna AT1 to reproduce received data, and outputs to the signal processing/control unit 160 .

The wireless communication unit 150 also performs processing for receiving a reference signal for spot discovery transmitted from the base station 300 (serving as positional information acquisition means).

The GPS signal receiver 151 cooperates with the signal processing/control unit 160, receives the GPS signal transmitted from the GPS satellite 20 through the second antenna AT2, and applies signal processing such as amplification, noise cancellation, and modulation, so as to be displayed on the GPS server system In 401 the information needed to calculate the geographic location of the cellular phone 100 is obtained.

The storage unit 152 cooperates with the signal processing/control unit 160, and stores programs to be executed in the signal processing/control unit 160, constant data used in the processing of the signal processing/control unit 160, variable data that must be temporarily stored, image Capture image data, etc.

The opening/closing judging unit 153 cooperates with the signal processing/control unit 160 to judge which of the above open state or closed state is the rotation state of the first housing 2 and the second housing 3 through the movable mechanism unit 4 . For example, the opening/closing judging unit 153 includes a detector such as a switch for detecting a closed state in which the first housing 2 and the second housing 3 are overlapped to distinguish the closed state from other states.

The key input unit 154, in cooperation with the signal processing/control unit 160, generates a signal according to any input operation (for example, pressing of a key performed with respect to the operation key 311 and the touch switch 35 for the camera module), and outputs it to the signal processing/control unit 160 .

The display unit 155 cooperates with the signal processing/control unit 160 to cause the display panel 21 to display an image based on the image data generated in the signal processing/control unit 160 .

Audio input/output unit 156, in cooperation with signal processing/control unit 160, converts input audio into an electrical audio signal at microphone 312, applies processing such as amplification, analog-to-digital conversion, and encoding to the signal, and converts the audio signal The processing result is output to the signal processing/control unit 160 . In addition, the audio processing unit 156 applies signal processing such as decoding, digital/analog conversion, and amplification to audio data input from the signal processing/control unit 160 to generate an audio signal, and converts it into audio at the speaker 22 .

The image capturing unit 157 cooperates with the signal processing/control unit 160 to capture images incident to the optical system 34 a to generate image data such as still images and moving images, and output them to the signal processing/control unit 160 . The image capturing unit 157 operates a flash to emit a flash of light from the light emitting window 321 at the time of image capturing under the control of the signal processing/control unit 160 .

The geomagnetic sensor 158 detects geomagnetism for calculating the azimuth. For example, as shown in FIG. 5 , the geomagnetic sensor 158 refers to the Cartesian coordinate system set on the main board 37 to detect the geomagnetism in each axis at a fixed position on the main board 37 . In order to detect the earth's magnetism, various methods are employed, such as a method using coil excitation, a method using a Hall effect, and a method using a magnetoresistive element.

In this embodiment, as an example, it is assumed that the geomagnetic sensor 158 is equipped with an analog-to-digital converter, and outputs the detected geomagnetic analog signal as an 8-bit digital signal, that is, an integer value from "0" to "255".

The signal processing/control unit 160 has a computer for executing processing according to programs stored in the storage unit 152 , and executes various processing regarding the overall operation of the cellular phone 100 .

For example, as processing regarding the telephone function, the signal processing/control unit 160 performs processing for controlling the order of calling and receiving via the wireless communication unit 150 according to key input operations in the key input unit 154 and Processing of audio data input/output at the audio processing unit 156 is transmitted/received.

As processing regarding the data communication function, the signal processing/control unit 160 responds to key input operations in the key input unit 154, operates the wireless communication unit 150, performs communication with a predetermined mail server system, and performs communication for transmission such as electronic mail. processing of data.

As processing regarding the image capturing function, the signal processing/control unit 160 executes processing for causing the image capturing unit 157 to perform still image and moving image capturing processing in response to a key input operation in the key input unit 154, and for sending the captured image to the captured image. A process of applying image processing such as compression and encoding to the data of the image and storing the result in the storage unit 152 , and the like. The signal processing/control unit 160 also performs processing for operating a flash at an appropriate timing when capturing a still image.

As processing regarding the map information display processing function, the signal processing/control unit 160 executes processing for calculating a geographical orientation from the detection value of the geomagnetic sensor 158, for transmitting information of a GPS signal received at the GPS signal receiver 151 Processing to the GPS server system 401 and acquiring positional information of the current spot, processing for transmitting the positional information to the navigation server system 402 and acquiring map information on the environment of the current spot, processing for finding the position based on the spot finding signal from the base station 300 and A process for calculating the current location based on the result of the bearing calculation, a process for controlling the orientation of the map on the display screen of the display unit 155 according to the result of the bearing calculation (heading up display process), and the like.

In order to cope with the fact that the orientation of the display panel 21 with respect to the user differs by 180 degrees between the open state and the closed state of the first casing 2 and the second casing 3, the signal processing/control unit 160 performs The process of rotating the display image of the display unit 155 according to the judgment result.

Next, the operation of the cellular phone 100 having the above configuration will be explained focusing on the map display processing function according to the present invention.

First, the GPS signal reception processing performed mainly by the signal processing/control unit 160 when the power of the cellular phone 100 is turned on is explained.

FIG. 7 is a flowchart illustrating an example of GPS signal reception processing in the cellular phone 100 .

The signal processing/control unit 160 controls the GPS signal receiver 151 (ST102, ST104) at a constant cycle (eg, interval of 2 seconds), and performs scanning to receive GPS signals from GPS satellites. When the scanning result is that the GPS signal can be received, the signal processing/control unit 160 stores the received GPS signal in the storage unit 152 (ST106). This scanning for GPS signals and storage of information is repeated for all GPS satellites from which data can be received (ST108, ST104, ST106). When scanning is performed for all GPS satellites, the signal processing/control unit 160 waits until the next GPS signal reception timing, and then performs the processing of steps ST104 to 108 again.

Next, the site finding process is explained.

FIG. 8 is a flowchart illustrating an example of spot finding processing in the cellular phone 100 .

For example, when the start point finding process is selected by a key input operation in the key input unit 154 (ST122), the signal processing/control unit 160 executes a method for transmitting the information obtained by the above-mentioned GPS reception process from the wireless communication unit 150 through the base station 300 and The communication network sends to the processing of the GPS server system 401 (ST124).

The GPS server system 401, when receiving GPS information from the cellular phone 100, calculates the position (such as latitude and longitude) of the current location of the cellular phone 100 based on the received GPS information, and transmits the calculation result from the communication network via the base station 300 to cell phone 100 .

The signal processing/control unit 160 receives the position information transmitted from the GPS server system 401, and stores it in the storage unit 152 (ST126).

Next, the signal processing/control unit 160 accesses the navigation server system 402 from the wireless communication unit 150 through the base station 300 and the communication network (ST128), and transmits the acquired position information to the navigation server system 402 (ST130).

When the navigation server system 402 receives the location information from the cellular phone 100, it retrieves map information of the current location environment of the cellular phone 100 indicated by the location information from the database, and transmits the retrieved map information from the communication network through the base station 300. to the cell phone 100.

The signal processing/control unit 160 receives the map information sent from the navigation server system 402, and stores it in the storage unit 152 (ST132).

FIG. 9 is a diagram showing an example of map information transmitted from the navigation server system 402 .

In this embodiment, as an example, it is assumed that a unique identification number is assigned to map information. The navigation server system 402 manages map data of each predetermined size (for example, 1 km square) based on the identification numbers, and when transmitting map information to the cellular phone 100, adds these identification numbers to the data for the transmitted map. In the example of FIG. 9 , the map of the current location environment has an identification number MP0, and maps in four directions around it have identification numbers MP1 to MP4.

The signal processing/control unit 160, upon receiving such map information, generates image data of a map on the current location environment based on the acquired map information, and displays the map on the display panel 21 of the display unit 55 (ST134).

The map area displayed on the display panel 21 is an area smaller than the 1 km square map acquired from the navigation server system 402 (for example, 200 m×300 m).

As the display method of the map, for example, either of north-up display (display that adjusts the north direction of the map toward the top of the screen) and course-up display (display that adjusts the forward direction on the map toward the top of the screen) can be selected.

When the north up display is selected by the key operation of the key input unit 154 , the signal processing/control unit 160 fixes the north direction of the map as the upward direction of the display screen and displays it on the display unit 155 .

When heading up display is selected by key operation of the key input unit 154, the signal processing/control unit 160 performs processing for controlling the orientation of the map on the display screen according to the orientation found by the orientation calculation process explained later. For example, when the direction A (see FIG. 2 ) directed from one end where the microphone 312 is located in the second housing 3 to the other end where the connection part is located is determined as the advancing direction of the cellular phone 100, the orientation of the control map on the display screen, Causes the orientation of the heading to be up on the display screen.

The “upward on the display screen” described here is viewed from the viewpoint of a user who holds the second housing 3 and uses the cellular phone 100 . When changing the open/closed state of the casings 2 and 3, "up on the display screen" changes accordingly. That is, when the housings 2 and 3 are in the open state, the side of the speaker 22 in the first housing 2 becomes the top of the display screen, and when the housings 2 and 3 are in the closed state, the side of the connecting part of the first housing 2 becomes the top of the display screen. Displays the top of the screen.

The signal processing/control unit 160 performs processing for rotating the image on the display screen according to the open/closed states of the casings 2 and 3 and displays the image in an appropriate orientation with respect to the user, as described later.

When the map display is started as described above, the signal processing/control unit 160 repeats the processing of step ST138 and subsequent steps to be explained next in the period until the end point finding processing (ST136) is selected by the key operation of the key input unit 154 .

First, the signal processing/control unit 160 causes the wireless communication unit 150 to receive reference signals for spot discovery transmitted from a plurality (for example, three or more) base stations 300 around the cellular phone 100, and The position of the current location is calculated (ST138). Then, the signal processing/control unit 160 judges whether there is any motion in the cellular phone 100 based on the calculation result of the current location (ST140), and when it is judged that the cellular phone 100 is not in motion, then performs the calculation of the current location based on the reference signal from the base station 300 (ST138).

When it is judged in step ST140 that the cellular phone 100 is in motion, the signal processing/control unit 160 judges whether the point to which the motion is going is in the end area of the currently acquired map (ST142). For example, when the part of the map to be displayed on the display unit is not included in the currently acquired map but is included in the adjacent map, it is determined that the current location is in the map end area.

When judging that the current location is in the terminal area, the signal processing/control unit 160 requests a map adjacent to the terminal area from the navigation server system 146 through the wireless communication unit 150 (ST146). For example, the signal processing/control unit 160 sends to the navigation server system 146 the identification number of the currently acquired map and information indicating in which direction the current location is adjacent to the map.

The navigation server system 146 detects a map from the database based on the information sent from the cellular phone 100 and sends it to the cellular phone 100 .

Signal processing/control unit 160 receives map information sent from navigation server system 402, stores it in storage unit 152 (ST132), and displays a map on display unit 155 according to the map information (ST134). Thereafter, the signal processing/control unit 160 repeats the processing of step ST138 and subsequent steps.

In addition, when judging that the current location is not in the end area, the signal processing/control unit 160 performs processing for moving the display area of the map based on the calculation result of the current location so that, for example, the current location of the cellular phone 100 becomes the displayed map center of. Thereafter, the signal processing/control unit 160 repeats the processing of step ST138 and subsequent steps.

Next, as an example of an "event" of the cellular phone 100, a process of rotating a display image according to a change in the opening/closing state of the casing will be explained.

FIG. 10 is a flowchart illustrating an example of processing of rotating a display image in the cellular phone 100 .

During power-on of the cellular phone 100, the signal processing/control unit 160 constantly monitors the open/close state judged in the open/close judgment unit 153 (ST162). When the opening/closing judging unit 153 judges that the shell is not in the closed state (that is, in the open state), the signal processing/control unit 160 displays an image on the display panel 21, and the image orientation makes the side of the speaker 22 in the first shell 2 become Image top (ST166).

When the display in the open state is a normal display, the signal processing/control unit 160 rotates the image in the normal display by 180 degrees and displays it on the display panel 21 when the opening/closing judging unit 153 judges that it is a closed state (ST164). That is, the signal processing/control unit 160 displays an image on the display panel 21 oriented such that the connection part side in the first housing 2 becomes the top of the image.

According to such rotation processing of the displayed image, regardless of the open/closed states of the housings 2 and 3, the image can always be displayed on the display unit 155 in an orientation that is easy for the user to observe.

Azimuth calculation processing

First, a method of calculating an azimuth will be briefly explained with reference to FIG. 11 , and then some examples of azimuth calculation processing in the signal processing/control unit 160 will be explained with reference to FIGS. 12 to 19 .

FIG. 11 is a diagram for explaining an azimuth calculation method.

In FIG. 11 , a Cartesian coordinate system having coordinate axes Hx, Hy, and Hz is a standard coordinate system set on a horizontal plane. The coordinate axes Hx and Hy are coordinate axes parallel to the horizontal plane, and the coordinate axis Hz is a coordinate axis whose direction is perpendicular to the horizontal plane.

The azimuth angle θ is the image obtained by orthogonal projection of the vector on the horizontal plane on the reference direction RD (for example, direction A in FIG. 2 ) of the geomagnetic detection set by the geomagnetic sensor 158 set on the main board 37 of the second housing 3 The angle formed by Zxy and the coordinate axis Hx. The inclination angle  is the angle formed by the image Zxy and the vector in the reference direction A. In addition, the twist angle η is an angle formed by rotating the cellular phone 100 around a rotation axis constituted by a vector in the reference direction A.

When the azimuth θ, inclination  and torsion η are all zero, the geomagnetic detection coordinate system set on the main board 37 of the second housing 3 is consistent with the coordinate system of the coordinate axes Hx, Hy and Hz shown in FIG. 11 .

When the geomagnetic detection value corresponding to the coordinate axis Hx according to the geomagnetic sensor 158 is α, the geomagnetic detection value corresponding to the coordinate axis Hy is β, and the geomagnetic detection value corresponding to the coordinate axis Hz is γ, as shown in FIG. 11 The tangent tanθ of the azimuth angle θ is expressed by the following equation.  is the inclination angle of the display panel 21 .

(equation 1)

tanθ＝β/(γ·sin-α·cos) …(1)

In equation (1), the twist angle η is set to zero.

The signal processing/control unit 160 calculates the azimuth angle by using the relationship shown in Equation (1) from the geomagnetic detection values in the three directions obtained from the geomagnetic sensor 158 .

When the signal processing/control unit 160 calculates the above-mentioned orientation, it also takes into account the inclination angle [phi] of the display panel 21 relative to the horizontal plane.

When the display panel 21 is tilted at an angle of, for example, about 45 degrees, the user can view the image of the display panel 21 in a comfortable posture. Therefore, when the inclination [phi] of the display panel 21 with respect to the horizontal plane becomes, for example, preferably 45 degrees, the signal processing/control unit 160 calculates the orientation according to equation (1) by using the inclination [phi].

When the down angle [phi] of the geomagnetic sensor 158 with respect to the horizontal plane is different in the open and closed states of the housings 2 and 3, the signal processing/control unit 160 may consider this difference in inclination to calculate the azimuths for these states. For example, unlike when the first case 2 and the second case 3 overlap almost in parallel in the closed state, it is assumed that the two cases are connected such that the first case 2 and the second case 3 are relatively inclined in the open state. In this case, when the user tries to keep the direction of line of sight relative to the display panel 21 constant in both operation modes, the inclination of the second housing 3 with respect to the horizontal plane differs between the open state and the closed state. The difference in inclination of the second housing 3 means that the inclination of the reference direction A with respect to the horizontal plane is different in the open and closed state. Therefore, the signal processing/control unit 160 performs the azimuth calculation using the inclination angle [phi] of a predetermined angle according to the determination result of the opening/closing determination unit 153 . This inclination angle [phi] is an angle set in advance so that when the inclination angle [phi] of the display panel 21 with respect to the horizontal plane is, for example, preferably 45 degrees, it remains constant in the open state and the closed state.

The information on the inclination angle [phi] is pre-stored in the storage unit 152 in the form of a data table, for example. When detecting the azimuth, the signal processing/control unit 160 reads the information of the inclination phi associated with the judgment result of the opening/closing judging unit 153 from the data table in the storage unit 152, and uses the information of the inclination phi to calculate the azimuth .

Azimuth calculation processing

FIG. 12 is a flowchart illustrating an example of azimuth calculation processing in the cellular phone 100 .

When the start point finding process is selected by a key input operation or the like at the key input unit 154, the signal processing/control unit 160 activates the geomagnetic sensor 158, and acquires orientation information (ST202), and then checks whether a predetermined event (phenomenon) occurs or ends the program (ST204).

The "predetermined event" here means an event that causes a change in the detection value of the geomagnetic sensor 158 in the circuits and processing systems in the cellular phone 100 when the orientation information (map displayed heading upward or compass indicating the orientation) is displayed on the display unit 155 . The predetermined events include, for example, events of operating the wireless communication unit 150 in the case of acquiring map information from the navigation server system 402 at step ST146 of FIG. 8 and in the case of executing call reception processing and mail reception processing. The predetermined events may include an event of changing display brightness on the display unit 155 according to a key input operation, a change of orientation information, a map display update, etc., an event of operating the audio processing unit 156 and outputting audio from a speaker, and the like. In the case where the display unit 155 has an LCD panel, as predetermined events, for example, an event of turning on/off a light source serving as a backlight of the LCD or changing the luminous intensity of the light source may be included.

When detecting occurrence of such a predetermined event, the signal processing/control unit 160 reads out previously prepared correction data of geomagnetic detection values corresponding to the detected event from the storage unit 152, and changes the currently used correction data.

FIG. 13 is a diagram showing an example of correction data.

In the example of FIG. 13 , the correction data includes three correction values corresponding to the X-axis, Y-axis, and Z-axis detection values of the geomagnetic sensor 158 . For example, when performing communication processing for operating the wireless communication unit 150, the signal processing/control unit 160 reads out the correction value “−1” corresponding to the X-axis, Y-axis, and Z-axis geomagnetic detection values from the storage unit 152 , "0" and "-1".

The storage unit 152 stores such correction data corresponding to a plurality of events, for example. Each correction value of the correction data is determined by measuring in advance the fluctuation amount of the geomagnetic detection value in the case where each event occurs and in the case where the event does not occur.

When the occurrence of a plurality of events is detected in step ST204 , the signal processing/control unit 160 adds correction values of correction data corresponding to the detected events to geomagnetic detection values in three directions. For example, in the example of FIG. 13, in the case where both communication processing and audio output processing occur, when the detection value of the geomagnetic sensor is ±255, the X-axis correction value becomes "-1"+"-1"=" -2", the Y-axis correction value becomes "0"+"0"="0", and the Z-axis correction value becomes "-1"+"0"="-1".

In addition, when the end of the specific event is detected in step ST204, the signal processing/control unit 160 subtracts the correction value of the correction data corresponding to the ended event from the current value. For example, in a state where the current X-axis, Y-axis, and Z-axis correction values are "-2", "-1" and "1" and the communication processing shown in FIG. 13 ends, the X-axis correction value becomes "- 2"-"-1"="-1", the Y-axis correction value becomes "-1"-"0"="-1", and the Z-axis correction value becomes "1"-"-1"=" 2".

The signal processing/control unit 160 corrects the detection value of the geomagnetic sensor 158 based on the correction data read out from the storage unit 152 (ST208). That is, the signal processing/control unit 160 adds the corresponding correction values of the correction data to the detection values in the three directions of the geomagnetic sensor. Then, by using this corrected geomagnetic correction value, the signal processing/control unit 160 calculates the azimuth using the calculation method described above (ST210).

During execution of the spot finding process, the signal processing/control unit 160 repeats the above-described processes of steps ST204 to ST210 (ST212).

As described above, according to the first example of the azimuth calculation process shown in FIG. )happened. The orientation information is corrected when an occurrence of a predetermined event is detected.

Therefore, even when the detection value of the geomagnetic sensor 158 changes due to the occurrence of an event and the accuracy of the azimuth information displayed on the display unit 155 decreases, the accuracy of the azimuth information can be restored by detecting the occurrence of the event and correcting the azimuth information.

In addition, correction data determined in advance for each event and stored in the storage unit 152 is used to correct the azimuth information, so the azimuth information can be corrected with high precision for each occurring event.

FIG. 14 is a flowchart illustrating still another example of azimuth calculation processing in the cellular phone 100 .

The difference between FIG. 14 and the above-mentioned FIG. 12 is that in the time period from the detection of the occurrence of a predetermined event to the calculation of the correction of the orientation information and the display of the orientation information of the calculation result on the display unit 155, the display on the display unit 155 is displayed on the display unit 155. The fact that the orientation information displayed on unit 155 is of low accuracy.

That is, when the occurrence of a predetermined event is detected in step ST204, the signal processing/control unit 160 displays on the display unit 155 the fact that the orientation information displayed on the display unit 155 is low in accuracy (step ST214). For example, when displaying a compass image representing an azimuth, the movement of the compass swinging left and right may be displayed to indicate that the accuracy of the azimuth information is low. In addition, it is possible to change the shape, color, and size of the compass image, or to display another image indicating a low accuracy of the azimuth.

The signal processing/control unit 160 displays information indicating a decrease in azimuth accuracy on the display unit 155 during changing the correction value (ST206), correcting the geomagnetism detection value (ST208), and calculating the azimuth (ST210). Then, when the corrected azimuth information is displayed on the display unit 155, when the azimuth accuracy is restored (ST211), the restoration is displayed on the display unit 155 (ST216).

For example, when a decrease in azimuth accuracy is indicated by the motion of panning the compass image side to side, the side to side panning may be discontinued to indicate restoration of azimuth accuracy. When a decrease in azimuth accuracy is shown by changing the shape, color, and size of the compass image, it can be returned to its original state to indicate the return of accuracy. Optionally, another image indicating the recovery of the accuracy of the orientation information may be displayed.

As described above, according to the second example of the azimuth calculation processing shown in FIG. 14, when the correction value of the magnetic detection value is changed due to the occurrence of a predetermined event (including the end of the event), the azimuth is recalculated using the new correction value and displayed on the display. During the display of the results on unit 155, the user may be notified of the fact that the accuracy of the displayed orientation information is low. For this reason, the user can correctly grasp whether the accuracy of the displayed orientation information is low.

FIG. 15 is a flowchart illustrating an example of azimuth calculation processing in the cellular phone 100 .

In the azimuth calculation processing examples of FIGS. 12 and 14 described above, changes in geomagnetic detection values due to occurrence of events on the internal processing side were corrected, but in the example of FIG. Closed state to correct changes in geomagnetic detection values.

The cellular phone 100 includes, for example, magnets (generating a static magnetic field different from the dynamic magnetic field generated for each event due to the internal processing described above) used in the speaker 22 and other components. Such a static magnetic field becomes a cause of a constant error (offset error) of geomagnetic detection values, and is corrected by offset error correction processing explained later. However, when the open/closed states of the housings 2 and 3 change, the positional relationship of these static magnetic field generation sources changes, and thus the offset error changes accordingly.

Therefore, in the azimuth calculation processing of the third example, in order to reduce the decrease in the accuracy of the azimuth calculation value due to such an offset error change, the offset error correction value obtained by the offset error correction processing is used alone as the Events for each of the states and closed states. Then, in the case where the opening/closing states of the casings 2 and 3 are changed, the correction value used in the offset error correction is changed in accordance with this.

When the start point finding process is selected by a key input operation or the like at the key input unit 154, the signal processing/control unit 160 activates the geomagnetic sensor 158, and acquires orientation information (ST302), and then checks the judgment result of the opening/closing judgment unit 153 ( ST304). When it is judged in the opening/closing judging unit 153 that the housings 2 and 3 are in the open state, the signal processing/control unit 160 reads, for example, an offset error of the open state held in a register not shown in the signal processing/control unit 160 Correct the data (ST306), and correct the detection value of the geomagnetic sensor 158 accordingly (ST307). In addition, when it is judged in the opening/closing judging unit 153 that the housings 2 and 3 are in the closed state, the signal processing/control unit 160 reads out the offset of the closed state held in a register not shown in the signal processing/control unit 160 Error correction data (ST308), and correct the detection value of the geomagnetic sensor 158 accordingly (ST309).

Note that the offset error correction data is composed of, for example, three correction values corresponding to geomagnetic detection values in three directions, as shown in FIG. 13 . These correction values are acquired frequently at the time of starting the spot finding process or during the execution of the spot finding process by the offset error correction process explained later, and are written in the signal processing/control unit 160 for each of the open and closed states. set in the predetermined register. When the offset error correction process is executed and a new correction value is acquired, the offset error correction data stored in the register is rewritten.

When correcting the detection value of the geomagnetic sensor 158, the signal processing/control unit 160 calculates the azimuth by using the corrected geomagnetic detection value (ST312).

Then, the signal processing/control unit 160 acquires the judgment result of the opening/closing judging unit 153 again, and checks whether the opening/closing state changes (ST314).

When detecting the change from the closed state to the open state, the signal processing/control unit 160 returns to step ST306, where it reads out the offset error correction data in the open state, and repeats the correction of the geomagnetic detection value by using the data. And the calculation of the orientation (ST307, ST312). When detecting the change from the open state to the closed state, the signal processing/control unit 160 returns to step ST308, where it reads out the offset error correction data in the closed state, and repeats the correction of the geomagnetic detection value by using the data. And the calculation of the orientation (ST309, ST312).

When the open/closed state has not changed, the signal processing/control unit 160 confirms whether the end point finding process is selected (ST316). When the spot finding process continues, the signal processing/control unit 160 repeats the correction of the geomagnetic detection value and the calculation of the azimuth by using the currently used offset error correction data (ST307/309, ST312).

When the end point finding process is selected, the signal processing/control unit 160 stores the offset error correction data of the open state and closed state held in the register in the storage unit 152 (ST318). Due to this operation, when the spot finding process is performed next time, by using the offset error correction data stored in the storage unit 152, the azimuth can be smoothly calculated.

As described above, according to the azimuth calculation processing example shown in FIG. 15, when the azimuth information is displayed on the display unit 155, a change in the judgment result in the open/close judgment unit 153 is monitored, and when a change is detected, according to the changed The orientation information displayed on the display unit 155 is corrected according to the state (open state or closed state). That is, when a change is detected, a predetermined correction corresponding to the changed state is performed on the detection values of the geomagnetic sensor 158, and the azimuth is calculated from these corrected geomagnetic detection values.

Therefore, in the cellular phone 100 configured so that the display unit 155 can display orientation information in both the open state and the closed state, even when the detection value of the geomagnetic sensor 158 changes with the occurrence of an event such as a change in the open/closed state and the resulting In a case where the accuracy of the displayed orientation information is lowered, the accuracy of the orientation information can be restored by detecting a change in the determination result in the open/close determination unit 153 and correcting the orientation information.

In addition, the offset error correction data of the open state and the closed state are separately held in a predetermined register of the signal processing/control unit 160, and the correction of the azimuth information is performed by using the appropriate offset error correction data according to the open/closed state, so The azimuth information can be corrected with high precision in each state.

Note that when the open/close state change is detected in step ST314, after the open/close state change is detected according to the judgment result of the open/close judgment unit 153, by utilizing the fact that the open or closed state will continue for a predetermined time after this change , and finally it can be judged from the open state to the closed state or from the closed state to the open state. For this reason, when the user accidentally touches the movable mechanism unit 4 and the opening/closing state change is detected immediately, it is possible to prevent erroneous changes of the offset error correction data.

FIG. 16 is a flowchart illustrating an example of azimuth calculation processing in the cellular phone 100 .

The difference between FIG. 16 and the above-mentioned FIG. 15 is that in the time period from the detection of the opening/closing state change event in the opening/closing judging unit 153 to recalculating the orientation and displaying the recalculated orientation information on the display unit 155 , the fact that the accuracy of the orientation information displayed on the display unit 155 is low is displayed on the display unit 155 .

The signal processing/control unit 160 detects a change in the open/closed state in step ST314, and accordingly reads out the offset error correction data according to the changed state in step ST306 or ST308, and then displays the data displayed on the display unit 155 on the display unit 155. The fact that the precision of the direction information is displayed is low (ST320).

The signal processing/control unit 160 (same as step ST214 of FIG. to display on the display unit 155 the information that the azimuth accuracy is degraded.

During correction of the geomagnetic detection value (ST307/309) and calculation of the azimuth (ST312), the signal processing/control unit 160 displays on the display unit 155 information indicating that the accuracy of the azimuth is degraded. Then, when displaying the corrected azimuth information on the display unit 155, the signal processing/control unit 160 displays the fact that the azimuth accuracy has been restored on the display unit 155 (ST322). For example, when a reduction in azimuth accuracy is indicated by a motion of the compass image swinging left and right, this swinging can be stopped. It is possible to restore the image to its original state when it shows that the bearing accuracy has decreased by changing the shape, color and size of the compass image. Optionally, another image indicating the recovery of the accuracy of the orientation information may be displayed.

As described above, according to the azimuth calculation processing example shown in FIG. 16, when the correction value of the magnetic detection value is changed due to a change in the opening/closing state of the cases 2 and 3, until the azimuth is recalculated by the new correction value and displayed on the display unit During the time period before the result is displayed on the screen 155, the user may be notified of the fact that the accuracy of the displayed orientation information is low. Due to this operation, the user can correctly grasp whether the accuracy of the displayed orientation information is low.

FIG. 17 is a flowchart illustrating an example of azimuth calculation processing in the cellular phone 100 .

In the azimuth calculation processing examples of FIGS. 15 and 16 described above, changes in geomagnetic detection values due to events such as changes in the open/closed states of cases 2 and 3 are corrected, but in the fifth example described below, corrections due to A change in the geomagnetic detection value due to an event such as loading a memory card into the memory card unit 159 .

When the memory card uses components that are easily magnetized (for example, the lead frame of a semiconductor integrated device), due to the influence of the magnetic force, the offset error of the geomagnetic sensor 158 is different when the memory card is loaded and not loaded under certain circumstances.

FIG. 18 is a graph showing an example of changes over time in geomagnetic sensor detection values (X-axis, Y-axis, and Z-axis) according to memory card loading. In the example of FIG. 18 , the detection values of the X-axis, Y-axis and Z-axis geomagnetic sensors are changed by exactly "-7", "-8" and "-1".

In the azimuth calculation processing example of FIG. 17, in order to reduce the azimuth error due to such a change in the detection value of the geomagnetic sensor, for each event of memory card loading and memory card unloading, an offset error correction process is individually maintained. The obtained offset error correction value. Then, when the loading state of the memory card in the casing changes, the correction value for offset error correction is changed in accordance with this.

When the start point finding process is selected by the key input operation at the key input unit 154, etc., the signal processing/control unit 160 activates the geomagnetic sensor 158, and acquires the orientation information (ST402), and checks the loading of the memory card in the memory card unit 159. into the state (ST404). When it is judged by a signal from the memory card unit 159 that the memory card is loaded, the signal processing/control unit 160 reads out, for example, offset error correction at the time of loading the memory card held in a register not shown in the signal processing/control unit 160 data (ST406), and correct the detection value of the geomagnetic sensor 158 accordingly (ST407). In addition, when it is judged by a signal from the memory card unit 159 that the memory card is not loaded, the signal processing/control unit 160 reads out the offset when the memory card is not loaded held in a register not shown in the signal processing/control unit 160 Error correction data (ST408), and correct the detection value of the geomagnetic sensor 158 accordingly (ST409).

The offset error correction data when the memory card is loaded and not loaded is composed of three correction values corresponding to geomagnetic detection values in three directions, as shown in FIG. 18 , for example. These correction values are acquired frequently at the time of starting the location finding process or during the execution of the location finding process by the offset error correction process explained later, and are written in the signal processing/control unit 160 for each time when the memory card is loaded and not loaded. in the predetermined register set by the state. When the offset error correction process is executed and a new correction value is acquired, the offset error correction data stored in the register is rewritten.

When correcting the detection value of the geomagnetic sensor 158, the signal processing/control unit 160 calculates the azimuth by using the corrected geomagnetic detection value (ST412).

Then, the signal processing/control unit 160 reconfirms the loading state of the memory card in the memory card unit 159 to check whether the loading state is changed (ST414).

When detecting a change from a state in which a memory card is not loaded in the memory card unit 159 to a state in which a memory card is loaded in the memory card unit 159, the signal processing/control unit 160 returns to step ST406, in which it reads out the loaded memory card The correction data of the offset error at the time is corrected, and the correction of the geomagnetic detection value and the calculation of the azimuth are repeated by using the data (ST407, ST412). When it is detected that the state in which the memory card is loaded from the memory card unit 159 is changed to the state in which the memory card is not loaded in the memory card unit 159, the signal processing/control unit 160 returns to step ST408, in which it reads out the memory card not loaded. The offset error correction data at the time of the card is used, and the correction of the geomagnetic detection value and the calculation of the azimuth are repeated by using the data (ST409, ST412).

When the loading state of the memory card has not changed, the signal processing/control unit 160 confirms whether or not the end location finding process is selected (ST416). When the spot finding process continues, the signal processing/control unit 160 repeats the correction of the geomagnetic detection value and the calculation of the azimuth by using the currently used offset error correction data (ST407/409, ST412).

When the end point finding process is selected, the signal processing/control unit 160 stores the offset error correction data held in the register in the storage unit 152 when the memory card is loaded and when the memory card is not loaded (ST418). Due to this operation, azimuth calculation can be smoothly performed by using the offset error correction data stored in the storage unit 152 when the spot finding process is performed next time.

As described above, according to the azimuth calculation processing example shown in FIG. 17, when azimuth information is displayed on the display unit 155, a change in the memory card loading state in the memory card unit 159 is monitored, and when a change is detected, according to the post-change The state (loaded or not loaded) to correct the orientation information displayed on the display unit 155. That is, when a change in the memory card loading state is detected, a predetermined correction corresponding to the changed state is performed on the detection value of the geomagnetic sensor 158, and the azimuth is calculated from the corrected geomagnetic detection value.

Therefore, even when the detection value of the geomagnetic sensor 158 changes due to a change in the loading state of the memory card and the accuracy of the azimuth information displayed on the display unit 155 decreases, by detecting the change in the loading state of the memory card in the memory card unit 159 and correcting Azimuth information, the accuracy of azimuth information can be recovered.

In addition, the offset error correction data in the loaded state and the unloaded state are separately held in a predetermined register of the signal processing/control unit 160, and the azimuth information is executed by using the appropriate offset error correction data according to the loaded state of the memory card , so the orientation information can be corrected with high precision in each state.

FIG. 19 is a flowchart illustrating an example of azimuth calculation processing in the cellular phone 100 .

The difference between FIG. 19 and the above-mentioned FIG. 17 is that in the time period from the detection of the loading state change event of the memory card to the recalculation of the orientation and the display of the recalculated orientation information on the display unit 155, the display unit 155 The fact that the precision of the orientation information displayed on the display unit 155 is low is shown.

The signal processing/control unit 160 detects a change in the loading state of the memory card at step ST414, accordingly reads out the offset error correction data according to the changed state at step ST406 or ST408, and then causes the display unit 155 to display the displayed value on the display unit 155. The fact that the accuracy of the direction information is displayed is low (ST420).

During correction of the geomagnetic detection value (ST407/409) and calculation of the azimuth (ST412), the signal processing/control unit 160 displays on the display unit 155 information indicating that the accuracy of the azimuth is degraded. Then, when displaying the corrected azimuth information on the display unit 155, the signal processing/control unit 160 displays the azimuth accuracy restoration on the display unit 155 (ST422).

For example, when a reduction in azimuth accuracy is indicated by a movement of the compass image swinging from side to side, this side-to-side panning can be discontinued. It is possible to restore the image to its original state when it shows that the bearing accuracy has decreased by changing the shape, color and size of the compass image. Optionally, another image indicating the recovery of the accuracy of the orientation information may be displayed.

As described above, according to the azimuth calculation processing example shown in FIG. 19 , when the correction value of the geomagnetic detection value is changed due to a change in the loading state of the memory card, until the azimuth is recalculated by the new correction value and displayed on the display unit 155 In the time period before the result, the user may be notified of the fact that the accuracy of the displayed orientation information is low. Due to this operation, the user can correctly grasp whether the accuracy of the displayed orientation information is low.

Offset Error Correction Processing

The offset error correction processing is processing for correcting a constant geomagnetism detection value error due to a magnetic field generation source inside the cellular phone 100 .

The static magnetic field generated inside the cellular phone 100 causes a constant error in the detection value of the geomagnetic sensor 158 regardless of the orientation in which the cellular phone 100 is located. Unlike this, the detection value of the geomagnetism itself changes depending on where the cellular phone 100 is located. Therefore, for example, by detecting the geomagnetism while rotating the cellular phone 100 and finding the path of the geomagnetic vector according to the rotation of the cellular phone 100, the offset error included in the detection value of the geomagnetic sensor 158 can be easily calculated.

Upon starting the place finding process, the signal processing/control unit 160 displays an instruction on the display unit 155 prompting the user to rotate the cellular phone 100 . When the user rotates the cellular phone 100 according to the instruction, the signal processing/control unit 160 acquires a plurality of detection values of the geomagnetic sensor 158 during the rotation, calculates an offset error difference based on the vector paths of the acquired geomagnetic detection values, and converts the difference Subtract from the detection value of the geomagnetic sensor 158 . Due to this operation, geomagnetic detection values in which offset errors are corrected are obtained.

The signal processing/control unit 160 stores the offset error calculated by the above-described offset error correction processing in a predetermined register of the signal processing/control unit 160 as offset error correction data.

Even during execution of the spot finding processing, the signal processing/control unit 160 executes the above-described offset error correction processing every fixed time.

Even when the detection value of the geomagnetic sensor 158 becomes a predetermined abnormal state (for example, overflow to be explained below), the signal processing/control unit 160 performs offset error correction processing and performs correction of the geomagnetic detection value.

FIG. 20 is a flowchart illustrating an example of offset error correction processing when a geomagnetic detection value occurrence abnormal state event occurs.

When the start location finding process is selected by key input operation or the like at the key input unit 154 (ST502), the signal processing/control unit 160 checks whether the detection value of the geomagnetic sensor 158 has become a predetermined abnormal state (ST504).

Here, the "predetermined abnormal state" means, for example, that an overflow occurs in any 8-bit detection value (ie, any X-axis, Y-axis, and Z-axis geomagnetic detection value) represented by an integer value of "0" to "255" , and its value changes to a maximum value of "255" or a minimum value of "0". In addition, a normal range with an upper limit and a lower limit is specified, and any geomagnetic detection value beyond the normal range can be defined as an abnormal state.

When such an abnormal state of the geomagnetism detection value is detected, the signal processing/control unit 160 counts the time period during which the abnormal state lasts from the detection moment (ST506). When the abnormal state continues for a predetermined time (for example, 5 seconds), the signal processing/control unit 160 judges that an offset error has occurred due to magnetization of the cellular phone 100 or the like, and performs the above-described offset error correction process (ST510).

After the offset error correction processing, the signal processing/control unit 160 checks whether to select to end the location finding processing. When the confirmation process continues, the signal processing/control unit 160 repeats the processing of steps ST504 to ST510 described above (ST512).

In addition, the signal processing/control unit 160 also confirms that the spot finding process continues in the case where the abnormal state of the geomagnetic detection value is not detected in step ST504 or in the case where it is judged in step ST508 that the abnormal state of all the detected values is resolved within a predetermined time , and then the processing of steps ST504 to ST510 is repeated (ST512).

As described above, according to the first example of the offset error correction processing shown in FIG. 20, when the azimuth information is displayed on the display unit 155, the detection value at the geomagnetic sensor 158 becomes a predetermined abnormal state and the abnormal state continues for a period of time. In the case of a predetermined time, the correction of the azimuth information is performed. That is, when any one (or more) of the geomagnetic detection values in the three directions becomes a predetermined abnormal state and the abnormal state lasts for a predetermined time, the offset error detection process of the geomagnetic sensor 158 and the correction of the offset error are performed processing (offset error correction processing), and recalculate the azimuth based on the corrected geomagnetic detection value. Therefore, by monitoring any abnormality in the detection value of the geomagnetic sensor 158, detecting the occurrence of an offset error of the cellular phone 100, and performing an appropriate correction, it is possible to suppress a decrease in accuracy of azimuth information due to an offset error.

In addition, according to the processing of FIG. 20 , the offset error correction processing is executed when the magnetic detection value becomes a predetermined abnormal state for more than a predetermined time. For this reason, it is possible to reduce cases where a temporary abnormal state in geomagnetic detection values due to the influence of, for example, an external magnetic field generated from a building or a train is erroneously judged as an offset error due to magnetization of the cellular phone 100, etc. Improper offset error correction processing was performed.

FIG. 21 is a graph showing an example of an abnormal state in a geomagnetic detection value due to the influence of an external magnetic field. In the example of the figure, the geomagnetic detection value in the Z-axis direction remains at "0" for more than 3 to 4 seconds. When such a temporary abnormality occurs due to an external magnetic field, when the offset error correction process is performed, the offset error cannot be calculated correctly, so the correction of the geomagnetism detection value is performed with an erroneous correction value, and thus the azimuth calculation result becomes incorrect. correct. The incorrect state of orientation persists at least until the next offset error correction process.

As shown in FIG. 21 , the abnormal state of the geomagnetic detection value due to the influence of the external magnetic field usually only lasts briefly for several seconds, and returns to a normal state within, for example, 5 seconds in many cases.

Therefore, as in the processing in FIG. 20, by distinguishing the abnormal state occurring due to the influence of the external magnetic field and the offset error according to whether the abnormal state continues for a predetermined time or longer, and controlling the execution of the offset error correction process according to this result, thereby Improper execution of correction processing can be effectively avoided.

FIG. 22 is a flowchart illustrating an example of offset error correction processing in the cellular phone 100 .

The difference between FIG. 22 and the above-mentioned FIG. 20 lies in the fact that the accuracy of the orientation information is displayed on the display unit 155 during the correction of the orientation information.

After judging in step ST508 that the geomagnetism detection value has been abnormal for a predetermined time or longer, the signal processing/control unit 160 causes the display unit 155 to display the fact that the accuracy of the azimuth information displayed on the display unit 155 is low (ST514).

During the offset error correction process ( ST510 ), the signal processing/control unit 160 displays on the display unit 155 information indicating that the azimuth accuracy has decreased. Then, when displaying the azimuth information recalculated from the corrected geomagnetic detection value on the display unit 155, the signal processing/control unit 160 displays the azimuth accuracy recovery on the display unit 155 (ST516).

For example, when a decrease in azimuth accuracy is shown by the movement of the compass image swinging left and right, this swinging from side to side may be discontinued. It is possible to return the compass image to its original state when it is shown that the azimuth accuracy has decreased by changing the shape, color, and size of the compass image. Optionally, another image indicating the recovery of the accuracy of the orientation information may be displayed.

As described above, according to the second example of the offset error correction process shown in FIG. 22 , during the correction of the azimuth information when the geomagnetic detection value appears abnormal, the user can be notified that the accuracy of the azimuth information displayed on the display unit 155 is low. fact. For this reason, the user can correctly grasp whether the accuracy of the displayed orientation information is low.

FIG. 23 is a flowchart illustrating an example of offset error correction processing in the cellular phone 100 .

The difference between FIG. 23 and the above-mentioned FIG. 22 is that the map display is fixed from the heading-up display to the north-up display during the correction of the above-mentioned overflowing azimuth information, and the heading-up display is restarted when the azimuth information correction is completed.

When it is judged in step ST508 that the abnormality of the geomagnetic detection value has continued for a predetermined time or longer, the signal processing/control unit 160 fixes the map display from the course-up display to the north-up display (ST518). During the offset error correction process (ST510), the north is continuously displayed. Then, when the azimuth is recalculated based on this corrected geomagnetic detection value, the signal processing/control unit 160 cancels the north-up display and restarts the heading-up display (ST520).

As described above, even in the example of the offset error correction processing shown in FIG. The fact that the accuracy of the orientation information displayed on the display unit 155 is low. Due to this operation, the user can correctly grasp whether the accuracy of the displayed orientation information is low.

Correction of errors due to the influence of external magnetic fields

Next, processing in a case where an error occurs in the detection value of the geomagnetic sensor 158 due to the influence of the external magnetic field and the accuracy of the azimuth information is lowered will be explained.

In general, buildings, trains, and the like include many magnetic field generating sources, and therefore, large errors occur in detection values of the geomagnetic sensor 158 due to the influence of external magnetic fields from these magnetic field generating sources in and around them. If the offset error correction process is performed in such an area, a wrong offset error is calculated, and therefore, a wrong offset error is actually displayed on the display unit 155 until the offset error correction process is performed again even after the user leaves the area. orientation information.

Therefore, in the processing described below, when it is detected that the user has entered an area where an error occurs in the detection value of the geomagnetic sensor 158 due to the influence of the external magnetic field or the like, the offset error correction processing is prohibited. In addition, the accuracy of displaying the orientation information on the display unit 155 is lowered, and a judgment on whether the user should use the orientation information as a reference is enabled.

FIG. 24 is a flowchart illustrating an example of processing in a case where an error occurs in a geomagnetism detection value due to the influence of an external magnetic field.

When the start point finding process is selected by a key input operation at the key input unit 154 or the like, the signal processing/control unit 160 activates the geomagnetic sensor 158, and acquires orientation information (ST602), and checks the GPS signal receiver 151 received Whether or not the level of the GPS signal is lower than a predetermined value (ST604).

Often, when the cellular phone 100 enters a building, the level of the GPS signal becomes very small, or even unacceptable. In this example, by utilizing this characteristic, it is judged whether or not the cellular phone 100 has entered the inside of the building.

When detecting that the GPS signal becomes lower than the predetermined value, the signal processing/control unit 160 judges that the cellular phone 100 has entered the inside of the building, and prohibits execution of the above-mentioned offset error correction process (ST606). For example, in the case of repeating the correction processing every constant time, the correction processing is not executed even after the constant time elapses. In this case, the signal processing/control unit 160 causes the display unit 155 to display the azimuth information with reduced precision (ST608). For example, the signal processing/control unit 160 causes the display unit 155 to display the reduced accuracy of the azimuth by, for example, swinging the compass image representing the azimuth left and right, changing the shape, color, and size of the compass, or displaying another image representing the reduced accuracy of the azimuth. Information.

On the other hand, when it is detected that the GPS signal becomes higher than the predetermined value, the signal processing/control unit 160 judges that the cellular phone 100 has not entered the inside of the building, and releases the Disabled (ST610). In this case, the signal processing/control unit 160 causes the display unit 155 to display the azimuth information with accuracy recovery (ST612). For example, when a decrease in azimuth accuracy is shown by the motion of shaking the compass image left and right, the right and left shaking may be terminated. It is possible to return the compass image to its original state when it is shown that the azimuth accuracy has decreased by changing the shape, color, and size of the compass image. Optionally, another image indicating the recovery of the accuracy of the orientation information may be displayed.

After step ST608 or ST612, the signal processing/control unit 160 checks whether to choose to end the place finding process. When the confirmation process continues, the signal processing/control unit 160 repeats the processing of the above-mentioned step ST604 and subsequent steps (ST614).

As described above, according to the processing example ( FIG. 24 ) when an error occurs in the geomagnetism detection value due to the influence of the external magnetic field, when the azimuth information is displayed on the display unit 155, the electric current of the GPS signal received at the GPS signal receiver 151 is monitored. flat. When it is detected that the level becomes lower than the predetermined value, it is judged that the cellular phone 100 has entered the inside of the building, and information indicating that the accuracy of the orientation information on the display unit 155 is low is displayed on the display unit 155 . Due to this operation, the user can correctly grasp whether the accuracy of the displayed orientation information is low. For example, when the accuracy of the orientation information is low, the user knows that the orientation must be predicted by other methods, for example, comparing the information displayed on the map with the feeling of the surroundings to determine the orientation without referring to the orientation displayed on the screen, so it is possible Improved user-friendliness of map information display processing functions.

In addition, in an inappropriate area (for example, inside a building) where an offset error cannot be correctly calculated due to the influence of an external magnetic field, execution of the offset error correction process is prohibited, so it is possible to reduce cases where the display unit 155 displays a wrong orientation for a long time.

Next, an example of processing when an error occurs in the geomagnetism detection value due to the influence of the external magnetic field will be explained with reference to the flowchart shown in FIG. 25 .

The difference between Figure 25 and the above Figure 24 is that the map display is fixed from the course up display to the north up display when the GPS signal is detected to become lower than the predetermined value, and restarted when the GPS signal is detected to be higher than the predetermined value The heading is displayed up.

When it is detected in step ST604 that the GPS signal becomes lower than the predetermined value, the signal processing/control unit 160 prohibits the offset error correction processing (ST606), and at the same time fixes the map display from the heading-up display to the north-up display (ST616) . In addition, when it is detected in step ST604 that the GPS signal becomes higher than the predetermined value, the signal processing/control unit 160 cancels the prohibition of the offset error correction process (ST610), and at the same time cancels the north-up display, and restarts the course-up display (ST618).

As described above, according to the processing example shown in FIG. 25 , in an area (for example, inside a building) where the accuracy of azimuth information decreases due to the influence of an external magnetic field, by fixing the map display to the north-up display, it is possible to notify the user The fact that the orientation information displayed on unit 155 is of low accuracy. Due to this operation, the user can correctly grasp whether the accuracy of the displayed orientation information is low.

Next, an example of processing when an error occurs in the geomagnetism detection value due to the influence of the external magnetic field will be explained with reference to the flowchart shown in FIG. 26 .

26 differs from the aforementioned FIG. 25 in that the azimuth calculation process and the operation of the geomagnetic sensor 158 are suspended when it is detected that the GPS signal becomes lower than a predetermined value, and restarted when it is detected that the GPS signal becomes higher than a predetermined value. these operations.

When it is detected in step ST604 that the GPS signal becomes lower than the predetermined value, the signal processing/control unit 160 fixes the map display from the course-up display to the north-up display (ST616), and simultaneously suspends the azimuth calculation processing and the geomagnetic sensor 158 Operation (ST620). When it is detected in step ST604 that the GPS signal has become higher than the predetermined value, the signal processing/control unit 160 cancels the north-up display and restarts the course-up display (ST618), and at the same time restarts the azimuth calculation process and the geomagnetic sensor 158's display. operation (ST622).

The inside of a building where it is generally difficult to receive a GPS signal is also an environment easily affected by an external magnetic field, but according to the processing example of FIG. In such an environment, the operation of the geomagnetic sensor 158 is suspended, thus suppressing supply of useless power to circuits not used in the cellular phone 100, and reduction in power consumption can be achieved.

Next, an example of processing when an error occurs in the geomagnetism detection value due to the influence of the external magnetic field will be explained with reference to the flowchart shown in FIG. 27 .

The difference between FIG. 27 and the above-mentioned FIG. 26 is that when it is detected that the GPS signal becomes higher than the predetermined value, after the azimuth calculation value is stabilized, the course upward display is resumed.

When it is detected in step ST604 that the GPS signal becomes higher than the predetermined value, the signal processing/control unit 160 restarts the azimuth calculation process and the operation of the geomagnetic sensor 158 (ST622), and then judges whether the azimuth calculation value becomes stable (ST624) . For example, the signal processing/control unit 160 judges that the bearing calculation value is stable when the variation degree of the bearing calculation result is within a predetermined range. After judging that the azimuth calculation value is stable, the signal processing/control unit 160 releases the north-up display and restarts the course-up display (ST618).

As described above, according to the processing example shown in FIG. 27 , when the signal level of the GPS signal becomes higher than a predetermined value and it is judged that the cellular phone 100 has left the inside of a building or the like, heading up is restarted after confirming that the azimuth calculation value is stable. show. For this reason, it is possible to avoid displaying low-accuracy azimuth information on the display unit 155 in a state where the geomagnetism detection value changes greatly due to the magnetic field from the building, for example, shortly after the cellular phone leaves the building.

Next, an example of processing when an error occurs in the geomagnetism detection value due to the influence of the external magnetic field will be explained with reference to the flowchart shown in FIG. 28 .

In the above-described processing examples (FIGS. 24 to 27), it is judged whether the cellular phone 100 has entered a building based on the reception level of the GPS signal, that is, whether the cellular phone 100 has entered a place where errors in geomagnetic detection are prone to occur due to the influence of an external magnetic field. in the area.

In the processing example explained next ( FIG. 28 ), based on information pre-registered in storage unit 152 , it is judged whether or not the current location of cellular phone 100 is included in an accuracy-reduced area that degrades the detection value accuracy of geomagnetic sensor 158 . When it is judged that the current point is included in the area, the offset error correction processing is prohibited. In addition, by causing the display unit 155 to display the orientation information with reduced accuracy, the determination of whether the user should use the orientation information as a reference is enabled.

When the start point finding process is selected by the key input operation of the key input unit 154, etc., the signal processing/control unit 160 activates the geomagnetic sensor 158, and acquires the orientation information (ST702), and judges whether the current position of the communication device is included in the storage unit In the reduced precision area registered in 152 (ST704).

The information of the degraded area registered in the storage unit 152 includes, for example, an identification number sent from the navigation server system 402 and coordinate information of the degraded area on the map (for example, information indicating the degraded area on the map by a coordinate range).

The signal processing/control unit 160 first retrieves the same identification number information as that of the currently displayed map from the information of the area of reduced precision registered in the storage unit 152 . When the retrieval result is that there is information of the same identification number, it is further judged whether the current location of the cellular phone 100 is included in the coordinate range of the accuracy-reduced area on the map indicated by the coordinate information. When the current location is included in the coordinate range, the signal processing/control unit 160 judges that the current location of the cellular phone 100 is included in the accuracy-reduced area.

When judging that the current location is included in the accuracy-reduced area, the signal processing/control unit 160 prohibits execution of the above-described offset error correction process (ST706). For example, when the correction processing is repeated every constant time, the correction processing is not performed even after the constant time elapses. In this case, the signal processing/control unit 160 causes the display unit 155 to display that the precision of the azimuth information has decreased (ST708). For example, the information of the reduced accuracy of the azimuth is displayed on the display unit 155 by, for example, shaking the compass image representing the azimuth left and right, changing the shape, color and size of the compass, or displaying another image representing the reduced accuracy of the azimuth.

On the other hand, when judging that the current location is outside the accuracy-reduced area, the signal processing/control unit 160 releases the prohibition as long as execution of the offset error correction process is prohibited (ST710). In this case, the signal processing/control unit 160 causes the display unit 155 to display the azimuth information with accuracy recovery (ST712). For example, when a decrease in azimuth accuracy is shown by the motion of shaking the compass image left and right, the right and left shaking may be terminated. It is possible to return the compass image to its original state when it is shown that the azimuth accuracy has decreased by changing the shape, color, and size of the compass image. Optionally, another image indicating the recovery of the accuracy of the orientation information may be displayed.

After step ST708 or ST712, the signal processing/control unit 160 checks whether to choose to end the place finding process. When the confirmation process continues, the signal processing/control unit 160 repeats the processing of step ST704 and subsequent steps (ST714).

As described above, according to the processing example ( FIG. 28 ) when an error occurs in the geomagnetism detection value due to the influence of an external magnetic field, it is judged whether the current location of the cellular phone 100 is included in the storage unit 152 when the azimuth information is displayed on the display unit 155 Registered in the reduced precision area. When the result of this judgment is that the current location is judged to be included in the accuracy-reduced area, information indicating that the accuracy of the orientation information on the display unit 155 is low is displayed on the display unit 155 . Due to this operation, the user can correctly grasp whether the accuracy of the displayed orientation information is low, so the user-friendliness of the map information display processing function can be improved.

In addition, in an accuracy-reduced region in which an offset error cannot be correctly calculated due to the influence of an external magnetic field, the execution of the offset error correction process is prohibited, so it is possible to reduce the display unit 155 from displaying a wrong orientation for a long time.

Next, a sixth processing example when an error occurs in the geomagnetism detection value due to the influence of the external magnetic field will be explained with reference to the flowchart shown in FIG. 29 .

The difference between FIG. 29 and the above-mentioned FIG. 28 is that the map display is fixed from the heading up display to the north up display when it is judged that the current location is included in the lowered accuracy area, and the heading up display is restarted when it is judged that the current location has moved out of the lowered accuracy area.

When it is judged in step ST704 that the current location of the cellular phone 100 is included in the accuracy-reduced area, the signal processing/control unit 160 prohibits the offset error correction processing (ST706), and at the same time fixes the map display from the heading-up display to the north-up display (ST716). In addition, when it is judged in step ST704 that the current location has moved out of the accuracy-reduced area, the signal processing/control unit 160 cancels the prohibition of the offset error correction value (ST710), and at the same time cancels the north-up display, and restarts the course-up display ( ST718).

As described above, according to the processing example shown in FIG. 29 , in an area where the accuracy of the azimuth information is lowered due to the influence of the external magnetic field, by fixing the map display to the north-up display, the user can be notified of the azimuth displayed on the display unit 155 The fact that the precision of the information is low. Due to this operation, the user can correctly grasp whether the accuracy of the displayed orientation information is low.

Next, an example of processing when an error occurs in the geomagnetism detection value due to the influence of the external magnetic field will be explained with reference to the flowchart shown in FIG. 30 .

The difference between FIG. 30 and the above-mentioned FIG. 29 is that when it is judged from the information of the storage unit 152 that the cellular phone 100 has entered the area of reduced accuracy, the azimuth calculation process and the operation of the geomagnetic sensor 158 are suspended, and when it is judged that the cellular phone 100 has moved out of the area of reduced accuracy, Restart these operations.

When it is judged in step ST704 that the current location of the cellular phone 100 is included in the accuracy-decreased area, the signal processing/control unit 160 fixes the map display from the heading-up display to the north-up display (ST716), and simultaneously suspends the azimuth calculation processing and geomagnetism Operation of the sensor 158 (ST720). When it is judged in step ST704 that the current location has moved out of the accuracy-reduced area, the signal processing/control unit 160 cancels the north-up display and restarts the course-up display (ST718), and at the same time restarts the azimuth calculation process and the operation of the geomagnetic sensor 158 ( ST722).

As described above, according to the processing example shown in FIG. 30 , in the area where the accuracy of the azimuth information is lowered due to the influence of the external magnetic field, the operation of the geomagnetic sensor 158 is suspended, thus suppressing useless power supply to circuits that are not used, and making it possible Realize power consumption reduction.

Next, an example of processing when an error occurs in the geomagnetism detection value due to the influence of the external magnetic field will be explained with reference to the flowchart shown in FIG. 31 .

FIG. 31 differs from the above-described FIG. 30 in that when it is judged that the cellular phone 100 has moved out of the accuracy-reduced area, the heading-up display is resumed after the bearing calculation value stabilizes.

After judging in step ST704 that the current location of the cellular phone 100 is outside the area of reduced accuracy and restarting the azimuth calculation process and the operation of the geomagnetic sensor 158 (ST722), the signal processing/control unit 160 judges whether the azimuth calculation value is stable (ST724). For example, the signal processing/control unit 160 judges that the azimuth calculation value is stable when the degree of fluctuation of the azimuth calculation result in a predetermined time is within a predetermined range. Then, after judging that the azimuth calculation value is stable, the signal processing/control unit 160 cancels the north-up display, and restarts the course-up display (ST718).

As described above, according to the processing example shown in FIG. 31 , when it is judged that the current location of the cellular phone 100 is outside the accuracy-reduced area, the heading-up display is restarted after confirming that the azimuth calculation value is stable. For this reason, when the geomagnetism detection value keeps fluctuating due to a magnetic field from a building or the like immediately after the current location moves out of the accuracy-reduced area, it is possible to avoid displaying low-accuracy azimuth information on the display unit 155 .

Next, the process of registering the precision-reduced area in the storage unit 152 in the above-described example of the process of correcting the influence of the external magnetic field ( FIGS. 28 to 31 ) will be explained with reference to the flowchart shown in FIG. 32 .

When the start point finding process is selected by key input operation or the like at the key input unit 154 (ST732), the signal processing/control unit 160 checks whether the detection value of the geomagnetic sensor 158 becomes a predetermined abnormal state (ST734).

Here, the "predetermined abnormal state" has the same meaning as explained for the offset error correction process of FIG. 20, for example. That is, a state in which an overflow occurs in any 8-bit detection value represented by an integer value of "0" to "255", and a state in which any geomagnetic detection value exceeds a predetermined normal range can be detected as an abnormal state.

When such an abnormal state of the geomagnetism detection value is detected, the signal processing/control unit 160 counts the time period during which the abnormal state lasts from the detection moment (ST736). Then, when the abnormal state ends within a predetermined time (for example, 5 seconds), the signal processing/control unit 160 judges that an error has occurred in the geomagnetic detection value due to an external magnetic field (ST738), and registers the current location in the storage unit 152 as an accuracy Lowered area (ST740).

By correspondingly storing the identification number of the map displayed when the geomagnetic detection value is abnormal and the information of the abnormal coordinates on the map (for example, including The coordinate range of the several-meter-square area of the place where the abnormality occurred), and the accuracy-reduced area is stored in the storage unit 152 .

Note that an upper limit may be set on the number of precision-reduced areas registered in the storage unit 152 . In this case, when the number of reduced precision areas registered in the storage unit 152 reaches the upper limit, when registering a new reduced precision area, the signal processing/control unit 160 may delete the oldest one from the already registered reduced precision area information. Information. Due to this operation, it is possible to prevent the registered information of the reduced-precision region from occupying the storage area of the storage unit 152 without limit, and at the same time, by leaving the latest information, the reliability of the reduced-precision region information can be improved.

After registering the reduced-precision area in the storage unit 152, the signal processing/control unit 160 checks whether the end point finding process is selected (ST742). When the confirmation process continues, the signal processing/control unit 160 repeats the processing of steps ST734 to ST740 described above.

In addition, when the abnormal state of the geomagnetic detection value is not detected in step ST734 or it is judged in step ST738 that the abnormal state of the geomagnetic detection value continues for a predetermined time or longer, the signal processing/control unit 160 also confirms that the spot finding process continues , and then repeat the processing of steps ST734 to ST740.

The preferred embodiments of the present invention are explained above, but the present invention is not limited only to the above aspects and includes various changes.

In the above-described embodiments, an example of azimuth calculation processing, an example of offset error correction processing, and a processing example when an error occurs in a geomagnetism detection value due to the influence of an external magnetic field were explained, but the embodiments of the present invention include all of any of these processing examples combination.

In the above-described embodiment, an example of geomagnetism detection in three directions in the geomagnetic sensor 158 was explained, but the present invention is not limited thereto. For example, two directions are also possible.

In the above-described embodiment, for example, in step ST208 of FIG. 14 , it was explained that the accuracy of displaying the orientation information on the display unit 155 is lowered, but the present invention is not limited thereto. For example, when this display is performed, when the azimuth information is corrected, the fact that the correction is being performed may be displayed on the display unit 155 . Alternatively, information indicating a reduction in accuracy and correction in progress may be displayed on the display unit 155 .

In addition, the display of bearing information may simply be stopped instead of displaying information such as decreased accuracy or ongoing correction. In this case, when the orientation correction is complete (or when the phone leaves the area of reduced accuracy), the user may be indicated to the user that the accuracy of the orientation information is restored by restarting displaying the orientation information.

In steps ST616 and ST618 of FIGS. 26 and 27, the display is fixed to the north-up display and released, but the present invention is not limited thereto. For example, azimuth accuracy reduction and azimuth accuracy recovery can be displayed in the same manner as in steps ST608 and ST612 of FIG. 24 .

In steps ST716 and ST718 of FIGS. 30 and 31 , the display is fixed to the north-up display and released, but the present invention is not limited thereto. For example, azimuth accuracy reduction and azimuth accuracy recovery can be displayed in the same manner as in steps ST708 and ST712 of FIG. 28 .

In the processing example ( FIGS. 28 to 31 ) when the geomagnetic detection value has an error due to the influence of the external magnetic field, the information of the accuracy-reduced area is acquired from the data table of the storage unit 152 , but the present invention is not limited thereto. This information can be obtained, for example, from a server system connected via the wireless communication unit 150 . That is, the signal processing/control unit 160 acquires information indicating whether the current location of the cellular phone 100 is included in the area of reduced accuracy from a predetermined server system through the wireless communication unit 150, and indicates in the acquired information that the current location is included in the area of reduced accuracy. When in the region, offset error correction processing can be disabled.

In the above-described embodiments, map rotation processing (for example, heading-up display) is performed in the cellular phone 100, but the present invention is not limited thereto. For example, cell phone 100 may specify an orientation to a map and request map information from navigation server system 402, and navigation server system 402 may generate map information for that orientation in response to the request from cell phone 100 and provide it to cell phone 100. That is, the signal processing/control unit 160 may perform a process of acquiring image information of a map from the navigation server system 402 and displaying it on the display unit 155 according to the bearing calculated based on the geomagnetic detection value. Then, during this processing, when it is detected that the detection accuracy of the geomagnetism detection value is lowered, for example, by the level of the GPS signal becoming lower than a predetermined value, the signal processing/control unit 160 may request the navigation server system 402 to set the orientation in advance. The image information of the map is acquired and displayed on the display unit 155 regardless of the calculated orientation.

In the above-described embodiments, the position calculation process is performed from GPS signals in the GPS server system 401, but the present invention is not limited thereto. Calculation of the found location may also be performed in the cellular phone 100 from GPS signals.

In the above-described embodiments, the map information is acquired from the navigation server system 402, but the present invention is not limited thereto, and the map information may also be stored in a storage device inside the cellular phone 100.

In the above-described embodiments, an example in which the processing of the signal processing/control unit 160 is executed by a computer according to a program has been explained, but at least a part of the processing may be executed by hardware instead of a computer.

Instead, at least part of the processing of other units than the signal processing/control unit 160 may be performed in the computer of the signal processing/control unit 160 .

In addition, the mobile communication device of the present invention is not limited to mobile phones. For example, the present invention can be widely applied in a mobile, and preferably portable, communication device having a communication function, such as a PDA (Personal Digital Assistant).

Claims (18)

1. A mobile map display device, comprising: Geomagnetic sensor for detecting geomagnetism, display unit, and The control unit can calculate the geographical orientation according to the detection value of the geomagnetic sensor, and has a first display process and a second display process. When the map is acquired and the display unit displays the map, the first display process is in accordance with the The direction associated with the calculated orientation is displayed, and the second display process is fixed at a predetermined orientation for display, wherein In displaying the map, the control unit performs display by the second display process when it is detected that the accuracy of the geomagnetic sensor has decreased. 2. The mobile map display device according to claim 1, wherein the control unit monitors the detection value of the geomagnetic sensor, and detects that the detection value exceeds a predetermined value, does not reach a predetermined value, or is unstable. At least one of the times is considered to have occurred. 3. The mobile map display device according to claim 1, wherein the control unit monitors the detection value of the geomagnetic sensor, and detects that the detection value exceeds a predetermined value, does not reach a predetermined value, or is unstable for a predetermined time The reduction in precision is considered to have occurred when at least one of the states of . 4. The mobile map display device according to claim 1, wherein the control unit monitors the detection value of the geomagnetic sensor, and when the detection value exceeds a predetermined value, does not reach a predetermined value, or is unstable at least One and when the duration of the state is within a predetermined time, the current position is stored in the storage unit as the area of reduced precision. 5. The mobile map display device according to claim 1, wherein said control unit considers that said decrease in accuracy has occurred when said calculated bearing is unstable. 6. The mobile map display device as claimed in claim 1, wherein, The device also has a GPS signal receiver for receiving GPS signals, and When the reception level of the GPS signal is low, the control unit considers that the decrease in accuracy has occurred. 7. The mobile map display device according to claim 6, wherein the control unit stops the geomagnetic sensor or stops calculation of the bearing when it is detected that a decrease in accuracy occurs. 8. The mobile map display device as claimed in claim 6, further having a location information acquiring unit for acquiring current position information according to the GPS signal and a wireless communication unit capable of being connected to a communication network, The control unit causes the wireless communication unit to acquire a map around the current position from the communication network as the map, based on the spot information acquired by the spot information acquiring unit. 9. The mobile map display device as claimed in claim 1, wherein, the device has a spot information acquiring unit for acquiring spot information of a current position, the surrounding map is associated with a region of reduced precision, and The control unit considers that the accuracy reduction has occurred when the current position is included in the accuracy reduction area. 10. The mobile map display device according to claim 9, wherein the control unit stops the geomagnetic sensor or stops the calculation of the bearing when it is detected that a decrease in accuracy occurs. 11. The mobile map display device according to claim 9, wherein the control unit monitors the detection value of the geomagnetic sensor, and when the detection value exceeds a predetermined value, does not reach a predetermined value, or is in an unstable state at least One and when the duration of the state is within a predetermined time, storing the current position in the storage unit as the precision-reduced area. 12. The mobile map display device according to claim 1, wherein, when the map is displayed by the second display process according to the detection of the decrease in accuracy, when the detection of the decrease in accuracy disappears, the control unit displays the map Change to the first display process. 13. The mobile map display device according to claim 1 , wherein, when displaying the map by the second display process according to the detection of the decrease in precision, when the detection of the decrease in precision disappears, the control unit according to the The detection value of the geomagnetic sensor calculates the geographic orientation, and changes the map display to the first display process. 14. The mobile map display device according to claim 13, wherein, when the detection value of the geomagnetic sensor does not meet any condition of exceeding a predetermined value, not reaching a predetermined value, or being unstable, the control unit executes the Describe the first display processing. 15. The mobile map display device according to claim 1, wherein said control unit monitors the occurrence of a predetermined event that changes the magnetic field in said mobile map display device, and when said predetermined event is detected to occur, at said The orientation is corrected according to this event in the first display process. 16. The mobile map display device as claimed in claim 15, wherein, The device also has two housings with at least one display unit, The two housings have a movable mechanism through which one housing having the display unit is connected to the other housing in a changeable positional relationship, and When a change in the open state of the movable mechanism is detected as the event, the control unit changes the display direction according to the positional relationship of the display unit with respect to the other housing when correcting the orientation. 17. A map display system, comprising a mobile map display device as claimed in claim 7 and a map providing device connected to a communication network, wherein the map providing device stores areas of reduced accuracy associated with surrounding maps, and The control unit also acquires the accuracy-reduced area when acquiring the surrounding map from the map providing device via the wireless communication unit. 18. A map display method in a mobile map display device, the mobile map display device comprising a geomagnetic sensor and a display unit for detecting geomagnetism, the method comprising: Calculation step, calculating the geographical orientation according to the detection value of the geomagnetic sensor; A map display step, acquiring a map and causing the display unit to display the map; a first display processing step of performing display in a direction associated with said calculated orientation; and The second display processing step is to perform display fixedly at a predetermined orientation, wherein When a reduction in accuracy is detected in the map display step, display is performed by the second display processing step.

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