JP2006011892A - Data storage device and mobile communication terminal with same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit the occurrence of an event suspending data write and read regardless of no actual drop of a data storage device by recognizing with high accuracy whether or not the data storage device actually has a drop. <P>SOLUTION: The data storage device is provided with: a data storage means storing data; a data processing means writing and reading the data to and from the data storage means; and an acceleration measurement means measuring acceleration developed in the data storage means. The data processing means suspends the data write and read to and from the data storage means when a period during which the absolute value of the acceleration measured by the acceleration measurement means is within a prescribed range with the absolute value of gravity acceleration as a center continues for a fixed period of time. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a data storage device including data storage means for storing data and data processing means for writing and reading data to and from the data storage means, and a mobile communication terminal having the data storage device Is.

  As this type of data storage device, for example, a device that magnetically records data on a disk (data storage means) using a head, a disk surface is deformed by a laser beam, or an optical characteristic of the disk surface is changed. Some of them record data, and others record data electrically in a semiconductor memory (data storage means). In general, such a data storage device causes various problems when subjected to an impact during writing or reading of data. For example, accurate data cannot be written or read, stored data that has already been stored is destroyed, or the data storage means itself is damaged.

Patent Document 1 discloses a disk storage device that can prevent erroneous writing to adjacent tracks even when an external impact is applied during data writing to the disk. This disk storage device has three acceleration sensors arranged to detect acceleration in three directions, and compares each output signal from these sensors with a constant acceleration default value independent of the acceleration direction. The comparison part to be provided is provided. When the comparison unit determines that any one of the output signals exceeds the predetermined acceleration value, an acceleration excess signal is sent to the write control circuit, and writing to the disk is prohibited. That is, according to this disk storage device, writing to the disk is prohibited immediately after the occurrence of a large impact that causes acceleration exceeding the predetermined acceleration value. According to the description in Patent Document 1, even if this large impact occurs, it is possible to prevent the head from moving to an adjacent track by this impact and erroneous writing to the adjacent track.
However, in this disk storage device, data writing is stopped after the impact is detected, so there is a time lag between the occurrence of the impact and the actual stop of data writing. Therefore, the head moves due to the impact between the occurrence of the impact and the actual stop of data writing, for example, the head touches the disc and damages the disc surface, or the data is in the wrong position. May be written. Therefore, as in the disk storage device disclosed in the above-mentioned Patent Document 1, if the writing of data is stopped after the impact is detected, a problem caused by receiving the impact during the writing or reading of data can be reliably ensured. It is difficult to avoid.

On the other hand, in Patent Document 2, when an impact due to a drop of a portable electronic device is received during a data writing operation, the power supply instantaneously stops due to the impact, and an abnormal current is generated in the memory card (data storage means). A portable electronic device that can prevent a memory card from being damaged due to fluctuations is disclosed. As an example, Patent Document 2 describes a portable electronic device including an open / close switch having a knob biased so as to protrude from the housing to the outside. In this portable electronic device, the opening / closing switch is turned off when the knob is pushed inside, and the opening / closing switch is turned on when the knob is exposed to the outside of the casing. In this portable electronic device, for example, it is assumed that the portable electronic device is dropped from the desk from the state where the portable electronic device is placed on a desk or the like so that the knob is pushed into the memory card while data is being written to the memory card. At this time, when the drop starts, the knob is exposed to the outside of the housing, and the open / close switch is turned on. In response to this, the control unit stops data writing to the memory card. As described above, since data writing is stopped before receiving an impact due to dropping, even if the impact is applied thereafter, an abnormal current fluctuation does not occur in the memory card, and the memory card can be prevented from being damaged.
As described above, according to Patent Document 2, data writing is stopped before the portable electronic device falls and receives an impact, so that the time lag unlike the disk storage device disclosed in Patent Document 1 does not occur. Therefore, it is possible to reliably avoid a problem that occurs due to an impact during data writing.

Japanese Patent Laid-Open No. 5-198078 JP 2003-18262 A

However, in the portable electronic device disclosed in Patent Document 2, the control unit recognizes that the portable electronic device is falling when the open / close switch is on. Therefore, for example, if the user lifts the portable electronic device placed on the desk, the controller erroneously recognizes that the open / close switch is turned on and the portable electronic device is falling, and stops writing data. I will let you. In addition, for example, even if the user places the portable electronic device on the desk so that the open / close switch does not turn off, the control unit erroneously recognizes that the portable electronic device is falling, and stops writing data. End up. As described above, the portable electronic device disclosed in Patent Document 2 is very limited in that the portable electronic device falls from the desk when the portable electronic device is placed on the desk or the like so that the open / close switch is turned off. Only under circumstances, the control unit cannot accurately recognize that the portable electronic device is falling. That is, the portable electronic device disclosed in Patent Document 2 has poor accuracy in recognizing whether or not the portable electronic device is actually dropped, and stops writing data even though it is not actually dropped. It had a problem that
Further, in Patent Document 2, an auxiliary switch having the same configuration as the open / close switch is provided in order to recognize that the user has lifted the portable electronic device placed on the desk. An example provided in the part is also disclosed. According to this example, when the user lifts the portable electronic device placed on the desk, the auxiliary switch is turned off if the user grips the grip, and the portable electronic device falls even if the open / close switch is turned on. If not, the control unit recognizes and does not stop data writing. However, for example, when the user grips without gripping the grip portion of the portable electronic device, the control unit erroneously recognizes that the portable electronic device is still falling, and stops data writing. Therefore, even in this example, the above-described problem still exists.

  Note that Patent Document 2 also describes an example in which an acceleration sensor is provided instead of the open / close switch. However, according to the description of Patent Document 2, when an acceleration applied to the main body of the portable electronic device is detected, a fall detection signal is output to the control unit, and the control unit detects that the portable electronic device is falling by the fall detection signal. It is going to be recognized. However, simply detecting the acceleration, the acceleration applied to the mobile electronic device body when it is not falling, for example, the acceleration when the user grips and moves the mobile phone, and the mobile electronic device body that is falling The applied acceleration cannot be distinguished. Therefore, even in this example, the above-described problem still exists.

  The present invention has been made in view of the above background, and the object of the present invention is to recognize with high accuracy whether or not it is actually falling, and to write data or not even though it has not actually dropped. It is an object of the present invention to provide a data storage device capable of suppressing the occurrence of a situation where reading is stopped and a mobile communication terminal including the data storage device.

In order to achieve the above object, the invention of claim 1 is a data storage device comprising data storage means for storing data, and data processing means for writing and reading data to and from the data storage means. An acceleration measuring means for measuring acceleration, wherein the data processing means has a period in which the absolute value of the acceleration measured by the acceleration measuring means is within a prescribed range centered on the absolute value of the gravitational acceleration for a certain period of time. The writing or reading of data with respect to the data storage means is stopped.
If the data storage device falls freely from its stationary state, an acceleration equal to the gravitational acceleration is generated in the data storage device. However, when the data storage device actually falls freely, there are far more cases where the data storage device falls while rotating (spinning) than when the data storage device freely falls in its posture. When falling while rotating, if the measurement position of the acceleration measuring means deviates from the center of rotation, the absolute value of the acceleration measured by the acceleration measuring means fluctuates with the rotation period around the absolute value of the gravitational acceleration. To do. Also, it must be taken into account that some measurement errors occur depending on the measurement accuracy of the acceleration measuring means. Therefore, in the data storage device of this claim, the reason why the writing or reading of data is stopped is that the absolute value of the acceleration measured by the acceleration measuring means is within a specified range centered on the absolute value of the gravitational acceleration. Only when the condition of 1 is satisfied. This specified range is appropriately set in consideration of the rotational speed at the time of free fall predicted according to the usage mode of the data storage device, the measurement accuracy of the acceleration measuring means, and the like.
On the other hand, even if the data storage device does not fall freely, for example, if the user moves the data storage device downward in the vertical direction, or if the data storage device vibrates vertically, The acceleration is within the specified range centered on the absolute value of acceleration. It may be measured instantaneously by the acceleration measuring means. Therefore, it is not possible to accurately recognize whether or not the data storage device is free-falling only by the first condition. Here, the probability of occurrence of the above-described problem that may occur when an impact is received during writing or reading of data generally tends to increase as the magnitude of the impact increases. Therefore, if a large impact with a high probability of occurrence of a defect can be effectively suppressed, the occurrence of the defect can be significantly suppressed. And such a big impact arises when it falls from a certain high position. Therefore, the occurrence of the above-described problem can be greatly suppressed if even a free fall that has a relatively long time from the start of the fall to the collision with the ground or the floor can be recognized.
Therefore, in the data storage device according to the present invention, in addition to the first condition, the second condition that the period satisfying the first condition continues for a certain period of time is used, and only when these conditions are satisfied. Stop writing or reading data. Thereby, by setting the predetermined range and the predetermined period as appropriate, even when the data storage device is not free-falling, the acceleration is instantaneously measured to be a value close to zero below a specified value. Can be eliminated. Note that the predetermined period is appropriately set according to the impact resistance determined by the device configuration employed for data writing or reading. For example, if the apparatus has a structure that can withstand the impact even if it falls freely when writing data or reading data from a height of up to 10 cm, the certain period may be set to about 0.14 seconds. With this setting, it is possible to accurately recognize a free fall from a height exceeding 10 cm before the impact.

According to a second aspect of the present invention, in the data storage device of the first aspect, the acceleration measuring means measures acceleration components in three orthogonal directions orthogonal to each other, and the acceleration of the acceleration used by the data processing means is measured. The absolute value is an absolute value obtained by combining the acceleration components measured by the acceleration measuring means.
When the data storage device falls while rotating (spinning), it is impossible to predict the direction of the rotation, and the direction of acceleration generated in the data storage device during free fall changes with the rotation period. Therefore, if the acceleration measuring means can only measure acceleration in one direction or can measure only acceleration in two directions orthogonal to each other, it accurately measures the absolute value of the acceleration generated in the data storage device during free fall. I can't. In the data storage device according to the second aspect of the present invention, as the acceleration measuring means, one that measures acceleration components in three axial directions orthogonal to each other is used, and an absolute value of a combination of the measured acceleration components is used as the absolute value of the acceleration. Utilizing this, data writing or reading is stopped. Therefore, even when the data storage device falls while rotating, the free fall can be recognized more accurately before the impact.

According to a third aspect of the present invention, the data storage device according to the first or second aspect is provided.
This mobile communication terminal has been standardized by PDC (Personal Digital Cellular) system, GSM (Global System for Mobile Communication) system, TIA (Telecommunications Industry Association) system mobile phone, etc., and IMT (International Mobile Telecommunications) -2000 Examples include mobile phones, TD-SCDMA (MC: Multi Carrier) type mobile phones that are one of TD-SCDMA (Time Division Synchronous Code Division Multiple Access) types, telephones such as PHS (Personal Handyphone Service), and automobile phones. . The mobile communication terminal only needs to have a display means and be used while being held by a user. In addition to the above-described telephone, a PDA (Personal Digital Assistance) having no telephone function is available. Mobile type mobile communication terminals are also included.

As described above, according to the first to third aspects of the present invention, as a result of being able to recognize with high accuracy whether or not it has actually dropped, writing and reading of data are stopped even though it has not actually dropped. The outstanding effect that generation | occurrence | production of the situation which is made to be able to be suppressed is show | played.
In particular, according to the second aspect of the present invention, even when the data storage device falls while rotating, it is possible to recognize the free fall more accurately before the impact and effectively suppress the occurrence of the above situation. An excellent effect of being able to be produced.

Hereinafter, an embodiment in which the present invention is applied to a mobile phone as a mobile communication terminal will be described with reference to the drawings.
2 is a front view showing an appearance of the mobile phone 20, and FIG. 3 is a schematic configuration diagram showing a hardware configuration of the mobile phone 20. As shown in FIG.
The mobile phone 20 is a clamshell (folding) type mobile phone, and includes an internal control device including a system bus 200, a CPU 201, a RAM 202, a ROM 203, an input device 204, an output device 205, a mobile phone communication device 206, an acceleration. A sensor 207 and a geomagnetic sensor 208 are provided. Components such as the CPU 201 and the RAM 202 exchange various data and instructions of a program to be described later via the system bus 200. The input device 204 includes a data input key (ten key, * key, # key) 21, a call start key 22, an end key 23, a scroll key 24, a multi-function key 25, a microphone 26, and the like. The output device 205 includes a liquid crystal display (LCD) 27 as a display means, a speaker 28, and the like. The mobile phone communication device 206 is for communicating with another mobile phone or a server device on the Internet via the mobile phone communication network 10.

The acceleration sensor 207 includes accelerations α _X and α _Y directed in two directions (X-axis direction and Y-axis direction in FIG. 2) orthogonal to each other in a plane parallel to the operation surface provided with the data input key. , A three-axis acceleration sensor serving as an acceleration measuring means for detecting an acceleration α _Z directed in the normal direction (Z-axis direction in FIG. 2) of the surface. The acceleration sensor 207 is mounted on a circuit board (not shown) provided inside the mobile phone 20, and a known sensor that can detect the accelerations α _X , α _Y , α _Z can be used.
The geomagnetic sensor 208 is a three-axis sensor that detects a magnetic field strength component (magnetic flux density component) of the geomagnetism on a three-dimensional coordinate composed of the X axis, the Y axis, and the Z axis. In the present embodiment, the angles θ _X , θ _Y , and θ _Z around the X axis, the Y axis, and the Z axis are detected using the detection result of the geomagnetic sensor 208. Specifically, the amount of change when the direction of the geomagnetism changes with respect to the reference geomagnetic direction (reference direction) is expressed as the angles θ _X , θ _Y , θ around the _X , _Y , and Z axes. Detect using _Z. Thereby, when the mobile phone changes its attitude from the attitude when the direction of geomagnetism is in the reference direction, the attitude after the change can be specified by each angle θ _X , θ _Y , θ _Z. In the following description, the angle θ _X around the X axis is referred to as the pitch angle, the angle θ _Y around the Y axis is referred to as the roll angle, and the angle θ _Z around the Z axis is referred to as the yaw angle. Further, the yaw angle θ _Z here indicates an angle between the horizontal projection Y-axis obtained by projecting the Y-axis on the horizontal plane and the north direction. Thus, the yaw angle theta _Z, can grasp the orientation horizontal projection Y-axis of the mobile phone 20 is oriented. The geomagnetic sensor 208 is also mounted on a circuit board (not shown) provided inside the mobile phone 20.
The acceleration sensor 207 and the geomagnetic sensor 208 may be configured as separate devices from the main body of the mobile phone 20. In this case, the acceleration sensor 207 and the geomagnetic sensor 208 are connected so that an external device including these sensors 207 and 208 is integrated with the main body of the mobile phone 20.

FIG. 4 is a block diagram showing extracted main parts of the mobile phone 20.
The cellular phone 20 includes a telephone communication unit 211 and a data communication unit 212 as wireless communication units, an operation unit 213 as operation units, a main control unit 215 as data processing units and data, an output unit 216, a sensor detection unit 217, A storage unit 218 as data storage means is provided.

The telephone communication unit 211 performs wireless communication with a base station of the mobile phone communication network 10 in order to perform telephone communication with other mobile phones or fixed phones. This corresponds to the device 206 and the like.
Similar to the telephone communication unit 211, the data communication unit 212 corresponds to the mobile phone communication device 206 having the above-described hardware configuration. The data communication unit 212 exchanges mail with other mobile phones via the mobile phone communication network 10 or connects to an external communication network such as the Internet from the mobile phone communication network 10 via a gateway server. This is for exchanging e-mails on the Internet, browsing web pages, and the like.
The operation unit 213 includes the above-described numeric keypad 21, a call start key 22, an end call key 23, and the like operated by the user 1. By operating the operation unit 213, the user can input data such as a URL to the mobile phone 20, and can start and end a call when an incoming call is received.

  The main control unit 215 controls the telephone communication unit 211, the data communication unit 212, the output unit 216, the sensor detection unit 217, and the storage unit 218, and includes the system bus 200, the CPU 201, the RAM 202, and the like. ing. The main control unit 215 functions as a data processing unit, and writes and reads data (including a program) to and from the RAM 202 of the storage unit 218 and reads data from the ROM 203 of the storage unit 218. The main control unit 215 performs communication control of the telephone communication unit 211 and the data communication unit 212 according to the data read from the ROM 203.

  The output unit 216 includes the output device 205 including the liquid crystal display 27 and the speaker 28 described above. The output unit 216 displays the Web page screen received by the data communication unit 212 on the liquid crystal display 27. The liquid crystal display 27 of the output unit 216 is used when the telephone communication unit 211 or the data communication unit 212 notifies the user that information has been received. Specifically, when the information is received, the main control unit 215 displays an incoming call notification image on the liquid crystal display 27 of the output unit 216 or outputs a ring tone from the speaker 28.

The sensor detection unit 217 includes the acceleration sensor 207 and the geomagnetic sensor 208 described above. The sensor detection unit 217 operates under the control of the main control unit 215, and the detection data is acquired by the main control unit 215. Data of accelerations α _X , α _Y , α _Z and pitch angle θ _X , roll angle θ _Y and yaw angle θ _Z as detection data are stored in the RAM 202 of the storage unit 218.
Further, when the posture of the mobile phone 20 changes, the magnetic field strength component (magnetic flux density component) after the change of the posture is detected by the geomagnetic sensor 208 constituting the sensor detection unit 217. The sensor detection unit 217 calculates the respective angles θ _x , θ _Y , and θ _Z after the posture change from the detection signal detected by the geomagnetic sensor 208. The data of the calculated angles θ _x , θ _Y , and θ _Z is output to the main control unit 215 and stored in the RAM 202 by the main control unit 215 as in the case of the accelerations α _x , α _Y , and α _Z. .
Further, when the orientation of the mobile phone 20 changes, the magnetic field strength component (magnetic flux density component) after the change of the orientation is detected by the geomagnetic sensor 208 constituting the sensor detection unit 217. The sensor detection unit 217 calculates the yaw angle θ _Z after the change in direction from the detection signal detected by the geomagnetic sensor 208. Data of the calculated yaw angle theta _Z likewise, is output to the main control unit 215, is stored by the main control unit 215 in the RAM 202.

The main control unit 215 obtains data of accelerations α _x , α _Y , α _Z and angles θ _x , θ _Y , θ _Z stored in the RAM 202 from the sensor detection unit 217 as follows. Things. For example, this is an acquisition method in which a request is sent from the main control unit 215 to the sensor detection unit 217, and the data output by the sensor detection unit 217 is received by the main control unit 215 accordingly. In addition, for example, an acquisition method may be employed in which the main control unit 215 appropriately receives data continuously output from the sensor detection unit 217 even when there is no request. In the present embodiment, an acquisition method in which the main control unit 215 appropriately receives data continuously output by the sensor detection unit 217 is employed.

  The storage unit 218 includes the above-described RAM 202, ROM 203, and the like. The RAM 202 and ROM 203 of the storage unit 218 store data necessary for data processing in the cellular phone, and the data is called up and used in the work area in the CPU 201 or RAM 202 as necessary. Here, the RAM 202 is composed of a data rewritable nonvolatile semiconductor memory that is generally widely used. When such a semiconductor memory is subjected to an impact during data writing or reading, accurate data writing or reading cannot be performed, already stored data is destroyed, or the memory itself is damaged. There is a risk of malfunction. In the mobile phone 20 that the user 1 carries or handles with his / her hand, the mobile phone 20 is often dropped due to carelessness of the user 1 and a strong impact is often applied. If this strong impact is applied during data writing or reading, the semiconductor memory may suffer from the above-described problems if it is impacted during data writing or reading. Therefore, in the present embodiment, as will be described below, it is accurately detected whether or not the mobile phone 20 is falling, and data writing and reading are stopped before an impact due to dropping is applied.

  Hereinafter, the data writing process of the main control unit 215 to the RAM 202 of the storage unit 218, which is a characteristic part of the present invention, will be described. The same applies to the data read processing of the main control unit 215 for the RAM 202 or the ROM 203 of the storage unit 218.

FIG. 1 is a flowchart showing a flow of data write processing of the main control unit 215 to the RAM 202 of the storage unit 218.
For example, it is assumed that the user 1 downloads data such as image data and an application program via the mobile phone communication network 10. In such a case, the main control unit 215 generates a data write process in order to save the downloaded data in the RAM 202 of the storage unit 218 (S1). When the data writing process occurs, the main control unit 215 first starts a sampling process for continuously acquiring data of the accelerations α _X , α _Y , α _Z detected by the sensor detection unit 217 (S2). After that, when the main control unit 215 samples a predetermined number of sets of acceleration α _X , α _Y , α _Z as one set, each set is specified by the data of acceleration α _X , α _Y , α _Z. The absolute value of acceleration obtained by combining the acceleration components of the X axis, Y axis, and Z axis is calculated (S3). Then, the main control unit 215 determines whether or not all of the calculated absolute values of acceleration are within a predetermined range (S4). If it is determined in this determination that it is within the predetermined range, the main control unit 215 recognizes that the mobile phone 20 is falling freely. As a result, the main control unit 215 stops the data writing process (S10) and displays a display command to the output unit 216 to display a notification screen indicating that the data writing process has been stopped on the liquid crystal display 27. Is output (S11). As a result, the user 1 is notified that the data writing process has been stopped in order to prevent the occurrence of problems due to the impact of dropping.

Here, when the mobile phone 20 is freely falling in a constant posture, the absolute value of the acceleration measured by the acceleration sensor 207 is theoretically equal to the absolute value of the gravitational acceleration. However, when the mobile phone 20 actually falls freely, there are far more cases where it falls while rotating (spinning) than when it falls freely in a fixed posture. When falling while rotating, if the installation location of the acceleration sensor 207 is deviated from the center of rotation, the absolute value of the acceleration obtained from the detection data of the acceleration sensor 207 is the rotation period around the absolute value of the gravitational acceleration. Fluctuates. In addition, some measurement errors may occur depending on the measurement accuracy of the acceleration sensor 207, and this error must be taken into consideration. Therefore, in the present embodiment, the specified range is set in consideration of the acceleration fluctuation according to the rotational speed within the range that can normally occur when the mobile phone 20 falls freely and the measurement error of the acceleration sensor 207. did.
Further, when the mobile phone 20 falls while rotating, it is impossible to predict the direction of the rotation, and the direction of the acceleration generated in the mobile phone 20 during free fall changes with the rotation period. Therefore, if an acceleration sensor that can measure only acceleration in one direction or an acceleration sensor that can measure only acceleration in two directions orthogonal to each other is used, the absolute value of the acceleration generated in the mobile phone 20 during free fall can be accurately measured. Can not. Therefore, in the present embodiment, the acceleration sensor 207 that measures acceleration components in three axial directions orthogonal to each other is used. Then, the absolute value of the combination of the measured acceleration components is recognized as the absolute value of the acceleration generated in the mobile phone 20. Thereby, even when the data storage device rotates freely while rotating, the free fall can be accurately recognized.
Also, the number of sets of acceleration data sampled in one sampling process, that is, the acceleration sampling period (fixed period), is an impact determined by the configuration of the RAM 202 to which data is written and the configuration of the device such as the writing method. It is set according to tolerance. In this embodiment, the RAM 202 to which data is to be written is a widely used semiconductor memory, and can withstand the impact even if it falls freely during data writing or data reading from a height of approximately 30 cm. It is a device configuration. Since the time required for the mobile phone 20 to collide with the floor or the ground when it freely falls from a height of 30 cm is about 0.25 seconds, in this embodiment, the data writing process is performed after the sampling process is completed. The sampling period is set to 0.2 seconds in consideration of the processing time until it actually stops. In this embodiment, since the output interval of acceleration data from the sensor detection unit 217 is 0.02 seconds, the number of sets of acceleration data sampled in one sampling process is set to ten. .

  If it is determined in S4 that the mobile phone 20 is not within the predetermined range, the main control unit 215 recognizes that the mobile phone 20 is not free-falling, and starts data writing processing to the RAM 202 of the storage unit 218 (S5). ). As a result, data is sequentially written into a predetermined memory area of the RAM 202. Even after the data writing process is started, the main control unit 215 performs the acceleration sampling process and the absolute value of the acceleration until the data writing process ends (S9), similarly to the processes of S2 to S4. It is determined whether or not all the calculated absolute values of acceleration are within a predetermined range (S6 to S8). In this determination, if it is determined in this determination that it is within the predetermined range, the main control unit 215 recognizes that the mobile phone 20 is free-falling. As a result, the main control unit 215 stops the data writing process (S10) and displays a display command to the output unit 216 to display a notification screen indicating that the data writing process has been stopped on the liquid crystal display 27. Is output (S11). As a result, the user 1 is notified that the data writing process has been stopped in order to prevent the occurrence of problems due to the impact of dropping.

In this embodiment, the sampling process is started after the data writing process occurs. However, the starting time of the sampling process is not particularly limited. For example, the sampling process is performed before the data writing process occurs. Also good.
In this embodiment, the data writing process or the data reading process with respect to the RAM 202 made of the semiconductor memory is taken as an example. However, the data storage means that may cause a problem when subjected to an impact caused by a natural drop during data writing or reading. If so, the same effect can be obtained in the data writing process or the data reading process for other data storage means. The data storage means may be an external storage device such as a memory card that can be attached to and detached from the main body, even if it is an internal storage device that is fixed to the main body as in the RAM 202 of this embodiment. May be. Specific examples of the external storage device include an SD memory card, a CF (compact flash: registered trademark) memory card, a smart media, a memory stick, and an MMC (multimedia card). Examples of the internal storage device include a hard disk device and an optical disk device such as a CD-ROM and a DVD-ROM. In a device configuration that writes and reads data with the head close to the recording surface (disk surface), such as a hard disk device, not only simply stop the data writing process, but also fix the arm that supports the head. It is desirable to retract the head to a position off the recording surface.
The present invention is not limited to the mobile phone 20 described above, and is widely useful for a data storage device provided with a data storage means that may cause a problem when subjected to an impact caused by a natural drop during data writing or reading. is there. In particular, in a mobile communication terminal that the user 1 carries or handles with hand, there are many situations where the user 1 falls freely due to carelessness of the user 1 and the like, so it is useful to apply this.

6 is an exemplary flowchart illustrating a flow of data writing processing of the main control unit with respect to the RAM in the mobile phone according to the embodiment. The front view which shows the external appearance of the mobile phone. The schematic block diagram which shows the hardware constitutions of the mobile phone. The block diagram which extracted and showed the principal part of the mobile phone.

Explanation of symbols

20 Mobile phone (mobile communication terminal)
207 Acceleration sensor (acceleration measuring means)
215 Main control unit 217 Sensor detection unit 218 Storage unit

Claims (3)

Data storage means for storing data;
In a data storage device comprising data processing means for writing and reading data to and from the data storage means,
Having acceleration measuring means for measuring acceleration;
The data processing means writes or reads data to or from the data storage means when the absolute value of the acceleration measured by the acceleration measuring means is within a specified range centered on the absolute value of gravitational acceleration for a certain period of time. The data storage device is characterized by stopping. The data storage device of claim 1,
The acceleration measuring means measures acceleration components in three axial directions orthogonal to each other,
An absolute value of the acceleration used by the data processing means is an absolute value of a combination of acceleration components measured by the acceleration measuring means.   A mobile communication terminal comprising the data storage device according to claim 1.

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