JP4741888B2 - Direction measuring device, direction measuring method and direction measuring program - Google Patents

Description

  The present invention relates to an azimuth measuring apparatus, an azimuth measuring method, and an azimuth measuring program that calculate a directional value by calculating a correction value by offset correction and calculating an azimuth based on the correction value.

  Conventionally, a function has been developed in which a small-sized electronic device such as a mobile phone is equipped with a two-axis magnetic sensor to measure geomagnetism and display the direction in which the electronic device is facing or display it superimposed on a map or the like. .

  In recent years, for example, the direction acquired by a magnetic sensor is set to three axes, and when the measurement magnetic field is abnormal, the device main body is rotated three-dimensionally to disturb the magnetic field provided by the device and the surrounding environment. A method is disclosed in which an accurate azimuth is calculated from the magnetic sensor value acquired and stored as an offset correction value and the offset correction value (see Patent Document 1).

  Furthermore, recently, with regard to the method of acquiring the offset correction value, an accurate azimuth is calculated from the magnetic sensor value and the offset correction value acquired sequentially, and a new offset correction is performed from the magnetic sensor acquired during this measurement as background processing. An azimuth measuring method in which values are integrated and reflected in the azimuth calculated next has been considered.

Such azimuth measurement by a magnetic sensor generally depends on an application program to be displayed using the azimuth measurement. Accordingly, the magnetic sensor starts to acquire magnetism under the control of the driver that receives the command signal from the program, and the driver corrects the offset value based on the acquired magnetism, and this process takes approximately 40 ms (0.04). Second).
JP 2004-286613 A

  However, in general, the more the number of times the offset correction value is measured in consideration of the surrounding environment, the higher the reliability, and in the case of a 3-axis sensor, the offset correction value is obtained with a minimum of 17 measurements. If you can't, you can't calculate the correct bearing in consideration of the surrounding environment. On the other hand, a request from a program to a driver that has been conventionally known is that the output interval of the request signal may be 1 second, and at least 17 seconds from the start of the program cannot be displayed accurately. was there.

  The present invention has been made in view of the above-described problems, and an object thereof is to perform accurate azimuth calculation in a short time from the start of azimuth measurement execution.

In order to solve the above problems, the orientation measuring apparatus according to the first aspect includes a magnetic detection means for detecting the magnetism and geomagnetism and offset magnetic field is synthesized, included depending on sensed the magnetic to the magnetic sensing means Storage means for storing information for calculating the offset magnetic field, offset magnetic field calculation means for calculating the offset magnetic field based on the information stored in the storage means, and the offset magnetic field calculation means calculated by the offset magnetic field calculation means the offset magnetic field, together with obtaining the geomagnetism by subtracting from the magnetic, the azimuth measuring device provided with a bearing calculating means for calculating an azimuth from said terrestrial magnetism obtained, in a first time interval, said azimuth calculating means display means for displaying the calculated azimuth, calculates the offset magnetic field in the first short second time interval than the time interval So that is characterized in that a that control means controls the offset magnetic field calculating means.

An azimuth measurement method according to a second aspect includes a magnetic detection step for detecting magnetism in which geomagnetism and an offset magnetic field are combined, and a storage unit that stores information for calculating an offset magnetic field included in the magnetism. And calculating the offset magnetic field based on the information, and calculating the offset magnetic field by subtracting the offset magnetic field calculated in the offset magnetic field calculation step from the magnetism, In an azimuth measuring method comprising an azimuth calculating step for calculating an azimuth from geomagnetism, a display step for displaying the azimuth calculated in the azimuth calculating step at a first time interval, and a first step shorter than the first time interval. to calculate the offset magnetic field in a second time interval, control the offset magnetic field calculating step It is characterized in that a that control step.

An azimuth measurement program according to a third aspect includes a computer having storage means for storing information for calculating an offset magnetic field included in magnetism, and a magnetic detection means for detecting magnetism in which geomagnetism and offset magnetic field are combined. Based on the information stored in the storage means, an offset magnetic field calculation means for calculating an offset magnetic field, and obtaining the geomagnetism by subtracting the offset magnetic field calculated by the offset magnetic field calculation means from the magnetism, In an azimuth measuring program that functions as an azimuth calculating unit that calculates an azimuth from the obtained geomagnetism, a display unit that displays the azimuth calculated by the azimuth calculating unit at a first time interval, from the first time interval to calculate the offset magnetic field in a short second time interval, the offset magnetic field calculated It is characterized in that function as that control means control the means.

  According to the present invention, when the input means inputs a request signal requesting acquisition of a bearing at the first time interval, the magnetic acquisition means is driven at a second time interval shorter than the first time interval to The azimuth calculation control is performed by acquiring the magnetism and updating the correction value, and updating the correction value sequentially, so that the azimuth can be calculated accurately in a short time from the start of the azimuth measurement. Is possible.

  Hereinafter, this embodiment will be described in detail with reference to the drawings. In addition, although it is set as the structure which mounts an azimuth | direction measurement program in a folding-type portable information terminal and performs azimuth | direction measurement, it is not limited to this. In addition, it is good also as a structure applied to a car navigation of a timepiece and a motor vehicle.

  First, FIG. 1 shows a schematic configuration diagram of a foldable portable information terminal 100 (hereinafter referred to as a mobile phone), where (a) is a plan view and (b) is a bottom view. The mobile phone 100 includes a call speaker 1, a main display unit 2, a key input unit 3, a call microphone 4, a sub display unit 5, a camera lens unit 6, a rechargeable battery 7, stereo speakers 8 and 9, an incoming call notification (also serving as Photography light) It is composed of an LED 10, a power connection terminal 12, a connector cover 13, and the like. Note that the call speaker 1, the main display unit 2, the sub display unit 5, the camera lens 6, and the incoming call notification (and photographing light) LED 10 are provided on the lid 101, the key input unit 3, and the call microphone 4. The rechargeable battery 7, the stereo speakers 8 and 9, the power connection terminal 12, the connector cover 13, and the antenna 14 (described later) are provided in the main body 102. The lid 101 and the main body 102 are configured to be foldable by a hinge 103.

  The call speaker 1 outputs the voice of the person who calls the user via the mobile phone 100.

  The main display unit 2 includes a display screen such as an LCD (Liquid Crystal Display), and is a main display screen for performing all operations. Displays phone book information, mail creation, recipient information for received calls, etc. In the present embodiment, when the azimuth measurement application is activated and the azimuth calculation is performed, the calculation result is displayed on the main display unit 2.

  The key input unit 3 includes a determination key 31, a cursor key 32, a camera key 33, direction measurement keys 34 and 35, and other various function keys. When inputting / receiving mails, creating mails, registering phone books, etc., various instructions are given by operating various function keys. When the camera mode is switched, operations such as white balance and zoom are input by the camera key 33. When the shooting target and other settings are completed, shooting is performed with the enter key 31. The decision key 31 has a setting decision button function and a shutter function.

  Furthermore, in this embodiment, direction measurement keys 34 and 35 are provided. The azimuth measurement key 34 is used when the cover of the mobile phone 100 is open, and the azimuth measurement key 35 is used when the cover of the mobile phone 100 is closed. When the azimuth measurement application is activated, the user requests azimuth acquisition by operating the azimuth measurement key 34 or 35. When receiving a press signal from the user, the control unit 20 controls the operation of each unit based on the received signal.

  Voice is input to the call microphone 4 by the user.

  The sub display unit 5 has the same configuration as the main display unit 2 and is an auxiliary display screen that displays an incoming call notification, a mail reception notification, receiving destination information, etc. when the mobile phone 100 is in a closed state. is there. When the mobile phone 100 is in a closed state, the direction is displayed on the sub display unit 5.

  The camera lens unit 6 switches the mobile phone 100 to the camera mode and displays an image on the main display unit 2 or the sub display unit 5 when taking an image.

  The rechargeable battery 7 is a power source for operating the mobile phone 100. The power connection terminal 12 is a terminal for connecting a power source when charging the rechargeable battery 7. The connector cover 13 is a cover for protecting a connector terminal connected when charging the rechargeable battery 7.

  The stereo-speakers 8 and 9 output a melody to notify the user that there is an incoming call, and, when used as a media player, stereo-output musical tone information by developing an audio file.

  The incoming call notification (cumulative shooting light) LED 10 not only notifies the user that there is an incoming call by light emission, but is also used as a light source for irradiating the subject in the camera mode.

  Next, with reference to FIG. 2, the main part structure of the mobile phone 100 is shown. As shown in the figure, the cellular phone 100 includes an antenna 14, a radio unit 15, a communication control unit 16, a system ROM (Read Only Memory) 17, a RAM (Random Access Memory) 18, an address in addition to the units shown in FIG. Data bus processing unit 19, control unit 20, storage unit 21, program ROM 22, display module system driver 23, piezo motor 24, DSP (Digital Signal Processor) 25, sound source IC 27, sensor unit 29, external interface controller 30, etc. The The DSP 25 includes a photographing module 26 such as a megapixel CCD (Charge Coupled Devices). The sound source IC 27 includes an AMP 28 and performs analog conversion by the AMP 28 and then outputs sound via the stereo speaker 9.

  The communication control unit 16 includes a communication data processing unit 161 and an audio interface 162. The communication data processing unit 161 includes a CELP (Code-Excited Linear Prediction) vocoder circuit, a speech decoding processing circuit, a packet data generation circuit, and a packet data restoration circuit, and executes data processing according to a communication protocol.

  The audio interface 162 inputs and outputs audio signals processed by the communication data processing unit 161.

  The radio unit 15 modulates CELP digital audio data output from the communication data processing unit 161 into a signal corresponding to a PSK (Phase Shift Keying) system, and modulates the signal into a spread code, and is received via the antenna 14. The code-modulated signal is decoded into a digital signal of the PSK system and / or QAM (Quadrature Amplitude Modulation) system.

  Specifically, when the user makes a phone call, the wireless unit 15 inputs the voice information input through the call microphone 4 and converted into a predetermined compression encoding format by the communication data processing unit 161 using the above-described method. Modulate and transmit to an external base station via the antenna 14. On the other hand, the radio signal received from the base station via the antenna 14 is demodulated into digital data, and the digital data is output to the audio interface 162 for voice communication. If the digital data is packet data, a process of outputting various data restored from the packet data to the control unit 20 is performed.

  The system ROM 17 stores various data necessary for basic OS and mobile phone 100 authentication, and stores a control program for communication control.

  The RAM 18 expands various programs executed by the control unit 20 in the program storage area. Further, the RAM 18 temporarily stores data such as processing results generated when executing various programs in the work area. For example, the RAM 18 stores various data (address book data, mail data, etc.) required for data communication processing and voice communication.

  The address / data bus processing unit 19 performs address control of the communication control unit 16 and the control unit 20 and control in the data flow of the bus.

  The piezo motor 170 is a motor for performing zoom control of the camera lens 6. When the camera mode is selected and a zoom adjustment instruction is input by operating the camera key 33 of the key input unit 3, the control unit 20 receives the input signal and controls the operation of the piezo motor 24 based on the input signal.

  The external interface controller 30 is, for example, a power supply for an 18-core connector and controls data transmission / reception.

  The DSP performs digital signal processing on the image photographed by the photographing module 26 and transmits the processed data to the control unit 20. Moreover, the operation | movement which takes over a part of operation | movement of the control part 20 is performed.

  Specifically, the sensor unit 29 is a magnetic sensor that acquires an orientation, and is, for example, a Hall element or a Hall IC. When an instruction from the control unit 20 is received, magnetic measurement is started. The measurement of magnetism is the measurement of the earth's magnetism and the resulting geomagnetism, and the offset magnetic field from a magnet whose position and strength are constant with respect to the magnetic sensor. Is calculated as the bearing. Specifically, the offset magnetic field to be corrected in the present embodiment is a magnetic field generated by the influence of a speaker, a vibrator, an open / close detection magnet, a memory card, etc. in the mobile phone 100. In addition, an offset magnetic field is generated when the application is activated, and the offset magnetic field frequently fluctuates when the application is activated. The correction for the offset magnetic field is an offset correction value (described later).

  The storage unit 21 stores multimedia data including captured and / or edited still images and moving images. Further, the offset correction value table 211 is stored. When magnetism is acquired by the sensor unit 29, the control unit 20 calculates an offset correction value by calculating an offset correction value based on the acquired magnetic data, and updates the offset correction value table 211 to the latest data. Therefore, the offset correction value table 211 is always the latest data updated every time the offset correction value is calculated.

  Here, offset correction will be described. Since the azimuth calculated when the offset magnetic field is generated is a combined vector of the geomagnetic vector and the offset magnetic field vector, an error occurs from the azimuth to be originally calculated. Therefore, when an offset magnetic field is generated, it is impossible to calculate a correct orientation unless offset magnetic field correction is performed. There are two general offset magnetic field correction methods: a method of measuring and storing an offset magnetic field in advance, and an adjustment operation during use. In this embodiment, since the orientation measurement program is installed in one of the application programs of the mobile phone 100, the magnetic field is always affected by fluctuations in the magnetic field due to the activation of the application program, incoming calls, incoming mails, etc. fluctuate. Therefore, since it is necessary to correct each time, a correction method for adjusting at the time of use is used.

  First, when the azimuth measurement program is activated and an operation signal is received from the user, the magnetic sensor of the sensor unit 29 acquires magnetic measurement data. Then, the offset magnetic field is calculated from these data, and the offset correction value is automatically calculated based on the azimuth measurement program. An azimuth calculation is executed based on this correction value, and the azimuth is displayed. Therefore, it is possible to perform a high-precision azimuth calculation from the measured value in the natural operation when the user uses the application.

  In the present embodiment, the azimuth measurement is always performed at short time intervals while the azimuth measurement program is activated. This azimuth measurement is performed regardless of an instruction from the user. When a azimuth acquisition request command from the user is detected, the azimuth calculated at the time of detection is displayed. Details will be described later.

  The control unit 20 executes processing based on a predetermined program in accordance with an input instruction, and transfers instructions and data to each functional unit. Specifically, the control unit 20 reads a program stored in the program ROM 22 in accordance with an operation signal input from the key input unit 3, and executes processing according to the program. Then, the processing result is displayed on the main display unit 2 or the sub display unit 5 via the display module system driver 23. The control unit 20 also includes a driver 201 that is software for operating peripheral devices.

  In the mobile phone 100 according to the present embodiment, the azimuth calculation is always executed by the driver side process as described above while the azimuth measurement program is activated. When the direction measurement key 34 is pressed by the user, the program side process outputs a direction acquisition request command to the driver side process. When the driver side process detects a command from the first program side process, after the elapse of 40 ms, the driver side process acquires the magnetism by the magnetic sensor and calculates the offset correction value described above. Then, the azimuth is calculated based on the calculated offset correction value, and the calculation result is output to the program side process cell. Then, the latest orientation is displayed on the main display unit 2 or the sub display unit 5 of the mobile phone 100.

  When the azimuth measurement result is displayed on the main display unit 2 or the sub display unit 5 after the first key operation from the user, the azimuth measurement does not end. In the mobile phone 100 of the present embodiment, the program side process is 1 s. Each time an orientation acquisition request command is output to the driver side process. The command output every 1 s is repeated regardless of the user's instruction. This 1 s interval corresponds to the first time interval.

  On the other hand, the driver-side process acquires magnetism at 100 ms intervals and calculates an offset correction value based on the acquired magnetism. This 100 ms interval corresponds to the second time interval. The offset correction value table is constantly updated, and the azimuth is calculated based on the offset correction value. When an azimuth direction acquisition request command from the program side process is detected while the azimuth measurement is executed at intervals of 100 ms, the main display unit 2 or the sub display unit 5 displays the azimuth measurement result calculated when the command is detected. To display. Therefore, the program side processing always acquires the direction calculation result by transmitting the direction acquisition request command at intervals of 1 s, and the driver side processing always executes the direction calculation at intervals of 100 ms, during which the direction acquisition request is issued. When a command is detected, the azimuth calculation result calculated at the time of detection is displayed. This process is repeated until a direction measurement application end instruction is transmitted by the user.

  The program ROM 22 stores programs necessary for the operation of the mobile phone 100 and application programs including downloads. For example, the program ROM 22 stores an orientation measurement program. Then, the control unit 20 reads the azimuth measurement program stored in the program ROM 22, and measures the azimuth by controlling the operation of each unit according to the program. For example, when a direction acquisition request instruction is transmitted by the user's operation of the key input unit 3 and the signal is received, the driver side process of the control unit 20 reads the direction measurement program stored in the program ROM 22. And magnetism is acquired by controlling operation of sensor unit 29. When magnetism is acquired, an offset correction value is calculated according to the azimuth measurement program, and a new offset correction value is calculated. When the offset correction value table is updated to the latest data, the azimuth is calculated based on the correction value. Then, the orientation obtained from the calculation result is displayed on the main display unit 2 or the sub display unit 5.

  As described above, the program-side process that is the operation of the control unit 20 that reads the one measurement program stored in the program ROM 22 and executes the operation executes processing around the application layer. In other words, it is a part of the network application that the user directly contacts, and performs communication between a program that performs transmission / reception via the network and a program that performs input / output with the user.

On the other hand, the driver-side process executed via the driver 201 of the control unit 20 is a process that is sequentially performed in the background of the program-side process that directly contacts the user as a user interface, and executes a process closer to hardware (device) To do.

  Next, processing executed by the mobile phone 100 based on the azimuth measurement program will be described with reference to the flowchart of FIG.

  First, when a direction acquisition request is made by the user operating the key input unit 3, the control unit 20 transmits a direction acquisition request command to the driver 201 (step P1). When an orientation acquisition request command is transmitted from the control unit 20 to the driver 201 in step P1, the driver 201 determines whether or not a command input has been detected (step S1). If it is determined in step S1 that no command input has been detected (step S1; NO), the process ends.

  If it is determined in step S1 that command input has been detected (step S1; YES), the driver 201 transmits an instruction to the sensor unit 29 to acquire magnetism by the magnetic sensor (step S2). In step S2, when a request for acquisition of magnetism by the magnetic sensor is transmitted, it is determined whether or not 40 ms has passed (step S3).

  If it is determined in step S3 that 40 ms has not elapsed (step S3; NO), the process returns to step S2 again to repeat the determination of whether 40 ms has elapsed.

  If it is determined in step S3 that 40 ms has passed (step S3; YES), the magnetism acquired by each magnetic sensor is acquired (step S4). In step S4, when the magnetism acquired by each magnetic sensor is acquired, an offset correction value is calculated from the acquired magnetism based on the program stored in the program ROM. When the correction value is calculated, the offset correction value table 211 stored in the storage unit 21 is updated to the calculated correction value (step S5). Note that the driver-side process realizes a magnetic acquisition unit by the process of step S4. Further, the correction value acquisition unit and the correction value update unit are realized by the process of step S5.

  In step S5, when an offset correction value is calculated and the offset correction value table 211 is updated, an azimuth is calculated based on the calculated correction value (step S6). In step S6, when the azimuth calculation is executed, the calculated calculation result is output to the control unit 20 that executes the program side processing. Note that the driver side process realizes an azimuth calculating means by the processing in step S6.

  In step P1, the control unit 20 that executes the program-side process transmits a bearing acquisition request command to the driver 201, and then determines whether or not the measurement result is received (step P3). ).

  If it is determined in step P3 that the calculation result has not been received (step P3; NO), the process returns to step P2 again and is in a standby state until the azimuth calculation result is received. Then, the determination in step P3 is repeated.

  If it is determined in step P3 that the calculation result has been received (step P3; YES), the received calculation result is displayed on the main display unit 2 (step P4). Here, when the cover of the mobile phone 100 is closed, the calculation result is displayed on the sub display unit 5.

  When the received calculation result is displayed on the main display unit 2 or the sub display unit 5 in step P4, it is determined whether or not 1 second has elapsed since the transmission of the azimuth acquisition request command in step P1 (step P5).

  If it is determined in step P5 that one second has not elapsed since the direction acquisition request command transmission in step P1 (step P5; NO), the process returns to step P4 again, and the calculation result acquired in step P3 is displayed on the main display unit 2 or the sub display. Displayed on the display unit 5. If it is determined in step P5 that one second has elapsed since the transmission of the azimuth acquisition request command in step P1 (step P5; YES), the azimuth acquisition request command is transmitted again to the control unit 20 (step P6). The transmission of the azimuth acquisition request command is not executed by a user operation, but is automatically transmitted when it is determined that one second has elapsed since the first azimuth acquisition request command transmission.

  On the other hand, in step S7, the control unit 20 performs an operation of displaying the azimuth calculation result on the main display unit 2 or the sub display unit 5 and enters a standby state (step S8). Then, it is determined whether 100 ms has passed (step S9).

  If it is determined in step S9 that 100 ms has not elapsed (step S9; NO), the process returns to step S8 again to enter a standby state. If it is determined in step S9 that 100 ms has passed (step S9; YES), the control unit 20 controls each magnetic sensor constituting the sensor unit 29 and acquires magnetism (step S10).

  In step S10, when the magnetism acquired by each magnetic sensor is acquired, an offset correction value is calculated from the acquired magnetism based on the program stored in the program ROM. When the correction value is calculated, the offset correction value table 211 stored in the storage unit 21 is updated to the calculated correction value (step S11).

  In step S11, when the offset correction value is calculated and the offset correction value table 211 is updated, the azimuth is calculated based on the calculated correction value (step S12). When the azimuth is calculated based on the calculated correction value in step S12, it is determined whether or not a azimuth acquisition request command has been detected (step S13).

  If it is determined in step S13 that the azimuth acquisition request command has not been detected (step S13; NO), the process returns to step S9 again to determine whether or not 100 ms has elapsed. Repeat the process. That is, until the next azimuth acquisition request command is detected, the offset correction value tag is updated many times, the azimuth calculation is executed based on the acquired correction value, and the latest azimuth is always calculated.

  In step P6, when the direction acquisition request command is transmitted to the driver side process by the program side process, the program side process enters a standby state (step P7). On the other hand, when a direction acquisition request command is transmitted from the program side process to the driver side process in step P6, the driver side process determines that the direction acquisition request command has been detected (step S13; YES).

  If it is determined in step S13 that an orientation acquisition request command from the program side process has been detected, the calculation result is output to the program side process (step S14). In step S14, when the driver side process outputs the calculated azimuth calculation result to the program side process, in step P7, the program side process in the standby state determines whether or not the azimuth calculation result has been received (step P8). ).

  If the program side process determines in step P8 that the operation result has been received (step P8; YES), the program side process displays the orientation that is the received operation result on the main display unit 2 or the sub display unit 5, and again, steps P5 to P5 are displayed. Repeat the process of P8.

  If it is determined in step P8 that the calculation result has not been received (step P8; NO), it is determined whether a program operation stop command has been detected (step P9). This program operation stop command is an instruction input by the user, and the user operates the key input unit 3 when ending the start of the azimuth measurement application.

  In step P9, when it is determined that the activation end instruction from the user, that is, the program operation stop command is not detected (step P9; NO), the process returns to step P5 again, and the processes of steps P5 to P9 are repeated.

  If it is determined in step P9 that a program operation stop command, which is an activation end instruction from the user, is detected (step P9; YES), the detected program operation stop command is transmitted to the driver side process, and the direction measurement application is ended.

  On the other hand, when the driver side process outputs the calculation result to the program side process in step S14, the driver side process determines whether or not a program operation stop command input is detected (step S15). If it is determined in step S15 that the program operation stop command input has not been detected (step P9; NO), the process returns to step S9 again, and the processes in steps S9 to S15 are repeated.

  In step S15, when it is detected that a program operation stop command is transmitted from the program side process (step S15; YES), the process is terminated.

  As described above, the azimuth measurement program mounted on the mobile phone 100 depends on the operation of the application program. Therefore, an offset magnetic field is generated, and an error is likely to occur in the measured azimuth. And calculating the azimuth based on the correction value, it is possible to display an accurate azimuth. Even if the user does not make a direction acquisition request, the driver side process executes the direction calculation at regular time intervals. When an orientation acquisition request from the program side process is detected, it is possible to provide an accurate orientation immediately by displaying the calculated orientation at that time.

  Furthermore, since the time interval of the azimuth calculation executed by the driver side process is shorter than the time interval of the azimuth acquisition request command transmitted from the program side process, until the next azimuth acquisition request, A direction calculation can be performed by performing correction several times. Accordingly, since the error is small, it is possible to display a more accurate azimuth.

An example of (a) front view and (b) rear view of a mobile phone to which the present invention is applied. The block diagram which shows an example of a function structure of a mobile telephone. The flowchart for demonstrating the specific operation | movement of a mobile telephone.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Speaker for call 2 Main display part 3 Key input part 31 Enter key 32 Cursor key 33 Camera key 34, 35 Direction measurement key 4 Call microphone 5 Sub display part 6 Camera lens 7 Rechargeable battery 8, 9 Stereo speaker 10 For incoming call notification (Cum shooting light) LED
12 power connection terminal 13 connector cover 14 antenna 15 radio unit 16 communication control unit 161 communication data processing unit 162 audio interface 17 system ROM
18 RAM
19 Address / data bus processing unit 20 Control unit 201 Driver 21 Storage unit 211 Offset correction value table 22 Program ROM
23 Display module system driver 24 Piezo motor 25 DSP
26 Shooting module 27 Sound source IC
28 AMP
29 sensor unit 30 external interface controller 100 foldable portable information terminal 101 lid 102 main body 103 hinge

Claims (3)

A storage means for the geomagnetism and the offset field stores the magnetic detecting means for detecting a magnetic synthesized, the information for calculating the offset magnetic field contained in the thus detected the magnetic said magnetic detection means, the storage means The offset magnetic field calculation means for calculating the offset magnetic field based on the information stored in the information and the offset magnetic field calculated by the offset magnetic field calculation means are subtracted from the magnetism to obtain the geomagnetism. In an azimuth measuring device comprising azimuth calculating means for calculating the azimuth from the geomagnetism ,
Display means for displaying the orientation calculated by the orientation calculation means at a first time interval ;
Said first a short second time interval than the time interval to calculate the offset magnetic field, that controls the offset magnetic field calculating means control means,
An azimuth measuring device characterized by comprising: A magnetic detection step for detecting magnetism in which the geomagnetism and the offset magnetic field are combined, and the information is read from storage means for storing information for calculating the offset magnetic field included in the magnetism. Based on the information, the offset magnetic field is read out. An offset magnetic field calculating step for calculating the magnetic field by subtracting the offset magnetic field calculated in the offset magnetic field calculating step from the magnetism, and an azimuth calculating step for calculating an azimuth from the obtained geomagnetism. In the direction measurement method provided,
A display step of displaying the azimuth calculated in the azimuth calculation step at a first time interval ;
To calculate the offset magnetic field in the first short second time interval than the time interval, the control step system wherein that controls the offset magnetic field calculating step,
A direction measuring method characterized by comprising: A computer comprising storage means for storing information for calculating an offset magnetic field included in magnetism ,
Magnetic detection means for detecting magnetism in which geomagnetism and offset magnetic field are combined , offset magnetic field calculation means for calculating an offset magnetic field based on the information stored in the storage means, and the offset magnetic field calculation means calculated by the offset magnetic field calculation means In the azimuth measurement program that functions as azimuth calculation means for calculating the azimuth from the obtained geomagnetism while obtaining the geomagnetism by subtracting the offset magnetic field from the magnetism ,
Display means for displaying the orientation calculated by the orientation calculation means at a first time interval ;
The first to calculate the offset magnetic field in a short second time interval than the time interval, that controls the offset magnetic field calculating means control means,
A direction measurement program characterized by functioning as

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