JP2009110633A - Data recorder, control method thereof, and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To retract a head of a hard disk drive during fall by appropriately detecting fall according to standard gravity determined according to a latitude. <P>SOLUTION: The data recorder includes a means for obtaining current latitude information of a GPS receiver or the like, and performs an appropriate fall detection according to standard gravity determined based on the latitude information. For each period, a fall detection control parameter is sequentially changed based on the latitude information. Thus, fall detection accuracy is maintained even in a north pole, a south pole, or on an equator. When a fall state is more accurately detected, the head of a hard disk drive can be retracted at proper timing. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a data recording apparatus for recording data on a recording medium, a control method therefor, and a computer program, and in particular, random access by a read / write head seeking on a recording surface such as a hard disk. The present invention relates to a data recording apparatus that records data on a recording medium that enables recording, a control method thereof, and a computer program.

  More specifically, the present invention relates to a data recording apparatus, a control method thereof, and a computer that reduce the risk of damage by retracting the head from the recording surface of the disk when the device is dropped based on the detection result of an acceleration sensor or the like.・ In relation to the program, in particular, the appropriate fall detection operation is performed according to the standard gravity determined according to the latitude, and the hard disk drive head is retracted in the fall state to prepare for the impact at the time of landing. The present invention relates to a data recording apparatus that implements the above, a control method thereof, and a computer program.

  With the development of information technology such as information processing and information communication, it has become necessary to reuse information created and edited in the past, and information storage technology has become increasingly important for this purpose. Up to now, information recording apparatuses using various media such as magnetic tapes and magnetic disks have been developed and spread. Of these, a disk-type recording medium such as a hard disk can basically be accessed randomly by the read / write head seeking in the radial direction on the recording surface of the rotating disk.

  Hard disks are already widespread. For example, as a standard local recording device for personal computers, various data files such as an operating system (OS) and applications necessary for starting up the computer are installed, created, or edited. A hard disk is used for saving.

  In addition, a hard disk is used as a local recording device or an external recording device in an information device that handles a large amount of data such as a digital video camera (for example, Patent Document 1, Patent). (Ref. 2). When a hard disk is used as a recording device for a digital video camera, digital recording of a large number of high-quality image data and random access to the recorded data are possible. You can edit images with. More recently, hard disk drives have also been used for devices that are designed to be carried mainly when moving, such as portable music players, and devices that are mounted on mobile objects such as navigation devices. ing. By using a hard disk for these information devices, it is possible to reduce the weight, volume, and cost of the apparatus compared to the case of using a removable magnetic tape or optical disk. In addition, since the size of the recording medium and the layout of the detachable part are not limited, the apparatus can be downsized and the degree of design freedom can be increased.

  The hard disk drive uses a technique in which an air layer is generated between the magnetic disk and the magnetic head by the rotation of the magnetic disk coated or vapor-deposited with a magnetic material, and the magnetic head is slightly floated. That is, when the magnetic disk is stopped, the magnetic head is lightly in contact with the magnetic disk surface, but the magnetic head is lifted by the flow of air generated by the rotation of the magnetic disk to perform recording and reproduction. High-density magnetic recording is realized by reducing the distance between the magnetic disk and the magnetic head while maintaining no contact.

  Because of this mechanism, the hard disk drive is regarded as a recording device that is vulnerable to shock. In particular, when a hard disk drive is installed in a device that is operated by hand, such as a digital camera or a portable device, if the user accidentally slides the device out of the hand during operation, it collides with the floor. There is a high risk that the head and the disk come into contact with each other and are damaged due to the impact applied.

  For this reason, some portable devices equipped with hard disk drives detect the fall using an accelerometer and protect the hard disk drive by retracting the head before colliding with the ground. Some are equipped with.

  In addition, in an information device equipped with a hard disk drive, an intermittent recording method is often applied from the viewpoint of reducing power consumption. For example, when shooting with a digital camera, the hard disk drive is paused, and the shooting data is temporarily stored in the buffer memory, and the data stored in the buffer memory is swept out and recorded on the hard disk only. Make the hard disk drive active. Here, the hard disk drive is vulnerable to external environmental changes in the active state, but in the hibernation state, the rotation of the disk is stopped and the head is fixed at the retracted position, so it may be able to withstand the impact Is strong. Therefore, when it is determined that safe data recording is not possible based on the detection result of the acceleration sensor or the like, the information processing apparatus performs processing for maintaining the hard disk drive hibernation state without shifting to the active state A proposal has been made for an imaging apparatus (see, for example, Patent Document 1).

  As a processing method to accurately determine the fall of a device, the current state of acceleration (gravity state) detected by an acceleration sensor and the history of acceleration changes are used to predict the state in which the device is starting to fall freely (See, for example, Patent Document 2), and by retracting the head at the predicted timing when it starts to fall freely, damage to the hard disk can be avoided.

  The acceleration applied to the falling equipment is basically gravitational acceleration. Here, gravity is the force that an object on the earth receives from the earth, and is the combined force of the universal gravitational force toward the center of the earth and the centrifugal force that tends to move away from the rotation axis due to the rotation of the earth. It is known that gravity does not go to the earth in places other than the poles and the equator, is the smallest on the equator, and increases toward the poles (the higher the latitude).

  In the drop detection algorithm for detecting the fall state of the device using the gravity acceleration detected from the acceleration sensor when the device is dropped and the history of gravity acceleration change as described above, the fall detection algorithm depends on the location where the device is used, that is, the latitude. The present inventor believes that an accurate fall state cannot be predicted unless the difference in gravity, that is, standard gravity determined according to latitude is taken into consideration.

  For example, if a device whose fall detection accuracy has been adjusted in Tokyo at the time of manufacture or shipment is operated to detect a drop on the equator, it will be easier to detect the drop compared to Tokyo, so it will not fall, even though it will not actually fall. As a result, the hard disk drive during the recording operation unnecessarily retracts the head. On the other hand, if the fall detection operation is performed at the North Pole or South Pole, it will be difficult to detect the fall compared to Tokyo, so even though it actually falls, the fall state is not predicted, and the head cannot be retracted when landing. The hard disk may be damaged.

JP 2007-208864 A JP 2007-87469 A

  An object of the present invention is to provide excellent data capable of suitably recording data on a recording medium that can be randomly accessed by a read / write head seeking on a recording surface such as a hard disk. To provide a recording apparatus, a control method therefor, and a computer program.

  A further object of the present invention is to provide an excellent data recording apparatus capable of reducing the risk of damage by retracting the head from the recording surface of the disk when the device is dropped based on the detection result of an acceleration sensor or the like, and its data recording apparatus A control method and a computer program are provided.

  A further object of the present invention is to perform an appropriate fall detection operation according to the standard gravity determined according to the latitude and to prepare for an impact at the time of landing such as retracting the head of the hard disk drive in the fall state. The present invention provides an excellent data recording apparatus, a control method thereof, and a computer program.

The present invention has been made in view of the above problems, and a first aspect thereof is a data recording apparatus for recording data on a recording medium,
Acceleration detecting means for detecting acceleration applied to the device;
Position information acquisition means for acquiring the current position of the device;
According to the current position acquired by the position information means, the fall detection control parameter for detecting the fall of the apparatus is switched based on the acceleration detected by the acceleration detection means and the history of acceleration change, and the apparatus A fall state judging means for judging the fall state of
A preventive operation control means for executing an operation for preventing the destruction of the recording medium according to a determination result of the fall state of the apparatus by the fall state determination means;
A data recording apparatus comprising:

  Randomly accessible recording media such as hard disks have become widespread and are used in computer systems such as personal computers, information equipment such as digital video cameras, portable music players, and navigation devices.

  A hard disk drive is a shock-sensitive recording device, and a hard disk drive is a shock-sensitive recording device. There is a high risk that the head and the disk come into contact with each other due to the impact and damage. For this reason, some portable devices equipped with hard disk drives detect the fall using an accelerometer and protect the hard disk drive by retracting the head before colliding with the ground. Some are equipped with.

  As a processing method to accurately determine the fall of a device, a method is proposed that predicts the state in which the device is starting to fall freely using both the gravitational acceleration detected from the acceleration sensor and the history of acceleration change at the time of the fall. Has been. However, it is known that gravity varies according to the latitude on the earth, and if the difference in gravity depending on the location where the device is used, that is, latitude, that is, standard gravity determined according to latitude is not taken into account, it is accurate. It is considered impossible to predict the falling state.

  Therefore, the data recording apparatus according to the present invention includes means for acquiring latitude information of a current location such as a GPS receiver, and performs an appropriate fall detection operation according to standard gravity determined based on the latitude information. I have to. When the falling state is detected more accurately, an operation in preparation for an impact at the time of landing, such as withdrawing the head of the hard disk drive, can be performed at an appropriate timing.

  For example, when operating the fall detection control in a certain period in the data recording apparatus according to the present invention, by sequentially changing the fall detection control parameter based on the latitude information obtained from the GPS reception signal or the like for each period, The same drop detection accuracy can be maintained even when in the North Pole or South Pole or on the equator.

According to a second aspect of the present invention, there is provided a computer program written in a computer-readable format so as to execute a process for controlling a data recording apparatus for recording data on a recording medium on a computer. Computer
Acceleration detecting means for detecting an acceleration applied to the data recording device and a history of acceleration changes based on an output of an acceleration sensor equipped in the data recording device;
Position information acquisition means for acquiring the current position of the device;
According to the current position acquired by the position information means, the fall detection control parameter for detecting the fall of the apparatus is switched based on the acceleration detected by the acceleration detection means and the history of acceleration change, and the apparatus A fall state judging means for judging the fall state of
A preventive operation control means for executing an operation for preventing the destruction of the recording medium according to a determination result of the fall state of the apparatus by the fall state determination means;
It is a computer program for making it function as.

  The computer program according to the second aspect of the present invention defines a computer program described in a computer-readable format so as to realize predetermined processing on the computer. In other words, by installing the computer program according to the second aspect of the present invention in the computer, a cooperative action is exhibited on the computer, and the same as the data recording apparatus according to the first aspect of the present invention. An effect can be obtained.

  According to the present invention, an excellent data recording apparatus capable of reducing the risk of damaging the head by retracting it from the recording surface of the disk when the device is dropped based on the detection result of an acceleration sensor or the like, and its control Methods and computer programs can be provided.

  Further, according to the present invention, an appropriate fall detection operation is performed according to the standard gravity determined according to the latitude, and the hard disk drive head is retracted in the fall state to prepare for an impact at the time of landing. It is possible to provide an excellent data recording apparatus capable of performing the operation, a control method thereof, and a computer program.

  When operating the fall detection control according to the present invention at a certain period, the fall detection control parameter is sequentially changed based on the latitude information obtained from the GPS reception signal, etc. Even when on the equator, the same drop detection accuracy can be maintained. The information device to which the present invention is applied can be manufactured anywhere in the world (on the earth), and the fall detection accuracy is adjusted, and the user is not restricted by the place (latitude) where the device is used. Even if it is used at any point of the throat, it is possible to realize the optimum fall detection performance.

  Other objects, features, and advantages of the present invention will become apparent from more detailed description based on embodiments of the present invention described later and the accompanying drawings.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 schematically shows the configuration of a digital video camera as an example of an apparatus that can operate as a data recording apparatus to which the present invention is applied.

  The illustrated digital video camera 100 includes an optical lens unit 111, a photoelectric conversion unit 112, a camera function control unit 102, an image signal processing unit 113, an image input / output unit 114, a liquid crystal display 115, and an audio input / output unit 116. An audio signal processing unit 117, a communication unit 131, a control unit 101, a built-in memory (RAM) 118, a built-in memory (ROM) 119, and an EEPROM (Electrically Erasable and Programmable) that stores predetermined data in a nonvolatile manner. A non-volatile memory 142 such as a ROM), an operation input unit 120, a drive 132 for a recording medium, sensors 150, and a power source 141 for supplying power to each of the above components.

  The control unit 101 is configured by a CPU (Central Processing Unit) or the like, but executes processing according to various processing programs stored in a ROM (read Only Memory) 119. A RAM (Random Access Memory) 118 is mainly used as a work area, such as temporarily recording intermediate results in each process. In response to an operation input from the user, the control unit 101 reads out and executes a program for performing a target process from the ROM 119, and controls each unit to control the process according to an instruction from the user. .

  The operation input unit 120 includes a mode switching key for switching operation modes such as a moving image shooting mode, a still image shooting mode, and a VTR mode, a shutter key for shooting a still image, a shooting start key for shooting a movie, a recording key, Various operation keys and function keys such as a play key, a stop key, a fast-forward key, and a fast-rewind key are provided, and an operation input from the user is received and an electric signal corresponding to the received operation input is supplied to the control unit 101 .

  In the moving image shooting mode or the still image shooting mode, the shooting data input through the optical lens unit 111 is composed of a CCD (Charge Coupled Device), a CMOS (Complementary Metal Oxide Semiconductor: Complementary Metal Oxide Semiconductor), or the like. The photoelectric conversion unit 112 performs photoelectric conversion. The image signal conversion unit 113 performs pre-processing such as correlated double sampling (CDS), AD conversion, automatic gain control (Automatic Gain Control: AGC), and then an appropriate color by AWB (Auto White Balance). Through state reproduction, resolution conversion, and color space conversion, encoding compression processing such as JPEG (Joint Picture Experts Group) or MPEG (Moving Picture Experts Group) is performed. The processed image data is recorded as a file on a recording medium.

  The digital video camera 100 can be mounted with various recording media such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., and records various information on these recording media via the drive 132, Information recorded on these recording media is reproduced.

  The magnetic disk mentioned here includes a so-called hard disk. The hard disk recording area is managed by a file system such as FAT (File Allocation Table), and upper layer programs such as applications and operating systems must access the recording area in the hard disk via the file system. Can do. The hard disk is driven and controlled by a dedicated device driver, and the file system issues host commands such as a write command and a read command to the device driver.

  The digital video camera 100 records image data obtained by capturing an image on various recording media such as a magnetic disk, an optical disk, a magneto-optical disk, and a semiconductor memory via a drive 132, and image input / output. It is provided with a “VTR mode” for recording data supplied through the recording unit 114, the voice input / output unit 116, or the communication unit 131 on a recording medium and reproducing data recorded on the recording medium.

  Under the image capturing mode, a moving image capturing mode for capturing a moving image and simultaneously recording a sound to be recorded on a recording medium and a still image capturing mode for capturing a still image are provided. In the VTR mode, the supplied data is recorded by operating the operation input unit 120 including a recording button / switch, and the recording is performed on the recording medium by operating the playback button / switch. The target data can be reproduced.

  Furthermore, the digital video camera 100 includes, as sensors 150, an acceleration sensor that detects acceleration applied to the device such as the start of dropping, a vibration sensor that detects vibration of the device, and a temperature sensor that detects the environmental temperature inside the device or where the device is placed.・ Humidity sensor that detects the humidity inside the device or the environment where the device is placed, an atmospheric pressure sensor that detects the pressure inside the device or the environment where the device is placed, and an outgas sensor that detects harmful gases such as siloxane on hard disks I have. Here, the acceleration sensor is composed of a three-axis acceleration sensor corresponding to three orthogonal axes of the X-axis, Y-axis, and Z-axis. For example, the X-axis, Y-axis, and Z-axis applied to the digital video camera 100 every 10 milliseconds. Acceleration (Gx, Gy, Gz) information corresponding to the three orthogonal axes is input to the control unit 101 at a predetermined cycle.

  In addition, the digital video camera 100 includes a GPS receiver 160 as a means for acquiring position information of a currently used place. The GPS receiver 160 inputs the obtained attitude information to the control unit 101 at a predetermined cycle. GPS (Global Positioning System) is a system that receives radio waves transmitted from multiple artificial satellites launched in low earth orbit and measures the longitude and latitude and altitude of the current position. The current position can be specified with an accuracy of several tens of meters (well known).

  FIG. 2 schematically shows the configuration of a personal computer as another example of an apparatus that can operate as a data recording apparatus to which the present invention is applied.

  A CPU (Central Processing Unit) 201 executes a program stored in the ROM 201 or the hard disk drive 211 under a program execution environment provided by an operating system (OS).

  A ROM (Read Only Memory) 202 permanently stores program codes such as POST (Power On Self Test) and BIOS (Basic Input Output System). The RAM 203 is used to load a program stored in the ROM 202 or the HDD 211 when the CPU 201 executes it, or to temporarily hold work data of the program being executed. These are connected to each other by a local bus 204 directly connected to a local pin of the CPU 201.

  The local bus 204 is connected to an input / output bus 206 such as a PCI (Peripheral Component Interconnect) bus via a bridge 205.

  A keyboard 208 and a pointing device 209 such as a mouse are input devices operated by a user. The display 210 includes an LCD (Liquid Crystal Display) or a CRT (Cathode Ray Tube), and displays various types of information as text and images.

  The HDD 211 has a built-in hard disk as a recording medium and drives the hard disk. The hard disk installs programs executed by the CPU 210 such as an operating system and various applications, and stores various local files such as media files such as moving images and still images, and data files. Used for.

  The recording area of the hard disk is managed by a file system such as FAT, and an upper layer program such as an application or operating system can access the recording area in the hard disk via the file system. The hard disk is driven and controlled by a dedicated device driver, and the file system issues host commands such as a write command and a read command to the device driver.

  The drive 212 reads data or a program recorded on a removable recording medium 221 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory, and inputs / outputs an input / output interface 207, an input / output bus 206, and a bridge 205. , And the RAM 503 connected via the local bus 204.

  The connection port 214 is a port for connecting the external connection device 222, and has a connection interface such as USB or IEEE1394. The connection port 214 is connected to the CPU 201 via the interface 207, the input / output bus 206, the bridge 205, and the local bus 204. The communication unit 215 is connected to a network and executes communication with other information processing apparatuses (not shown).

  For example, sensors 230 can be connected to the connection port 214. The sensors 230 include an acceleration sensor that detects acceleration applied to the device such as the start of dropping, a vibration sensor that detects vibration of the device, a temperature sensor that detects the ambient temperature inside the device or the device, Examples include a humidity sensor that detects the ambient humidity placed, a pressure sensor that detects the atmospheric pressure inside the device or the environment in which the device is placed, an outgas sensor that detects harmful gas to a hard disk such as siloxane. Here, the acceleration sensor is composed of a three-axis acceleration sensor corresponding to three orthogonal axes of the X-axis, Y-axis, and Z-axis. For example, the X-axis, Y-axis, and Z-axis applied to the digital video camera 100 every 10 milliseconds. Acceleration (Gx, Gy, Gz) information corresponding to the three orthogonal axes is input to the control unit 101 at a predetermined cycle.

  In addition, a GPS receiver 260 is also connected to the connection port 214 as a means for acquiring position information of a currently used place.

  The digital video camera 100 shown in FIG. 1 is equipped with a hard disk drive as a main data recording device. Still image data, moving image data, audio (or music) data obtained by taking an image through a camera unit including the optical lens unit 111 and the photoelectric conversion unit 112, or supplied from an external device through the image input / output unit 114 Still image data and moving image data, and still image data and moving image data supplied via the communication unit 131 can be recorded on the hard disk. Also, in the information device such as the personal computer 200 shown in FIG. 2, the editing data, the still image data or the moving image data supplied via the connection port 214 or the communication unit 215 are recorded on the hard disk. be able to.

  Here, the hard disk drive is regarded as a shock-sensitive recording device, and the hard disk drive is regarded as a shock-sensitive recording device. If the user accidentally slides the device out of the hand during operation, it collides with the floor. There is a high risk that the head and the disk come into contact with each other and are damaged due to the impact applied. For this reason, some portable devices equipped with hard disk drives detect the fall using an accelerometer and protect the hard disk drive by retracting the head before colliding with the ground. Is essential.

  In the present embodiment, a fall detection control method for predicting a state where the device starts to fall freely using both the current acceleration detected from the acceleration sensor and the history of acceleration change (see Patent Document 2). Apply). Hereinafter, the drop detection control in the digital video camera 100 shown in FIG. 1 will be described, but it should be understood that the present invention can be similarly applied to other types of information devices such as the personal computer 200.

  The acceleration sensor is composed of a three-axis acceleration sensor corresponding to three orthogonal axes of the X, Y, and Z axes. For example, the X, Y, and Z axes are orthogonal to the digital video camera 100 every 10 milliseconds. Acceleration (Gx, Gy, Gz) information corresponding to the axis is input to the control unit 101 (described above).

  The control unit 101 periodically inputs acceleration (Gx, Gy, Gz) information detected by the acceleration sensor, records the information in the built-in memory 118, and accelerations corresponding to three orthogonal axes of the X axis, the Y axis, and the Z axis. A composite value Gavg based on (Gx, Gy, Gz) is calculated, and the calculated composite value Gavg is recorded in the built-in memory 118 together with accelerations (Gx, Gy, Gz) corresponding to the three orthogonal axes. The composite value is a value calculated as the sum of squares of acceleration values corresponding to three orthogonal axes of the X axis, the Y axis, and the Z axis, for example, as shown in the following equation.

  The control unit 101 records the acceleration (Gx, Gy, Gz) in each orthogonal axis direction and the combined value Gavg calculated based on the output value of the triaxial acceleration sensor at each measurement timing in the built-in memory 118. As a result, in the built-in memory 118, acceleration history information according to the time transition of the acceleration (Gx, Gy, Gz) in each orthogonal axis direction and the composite value Gavg is recorded.

  Then, the control unit 101 determines whether the digital video camera 101 is in a fall state based on the input value from the triaxial acceleration sensor and the acceleration history information recorded in the built-in memory 118. The control unit 101 can distinguish and determine whether the digital video camera 101 is in a state that the user holds and swings up or down, for example, or in a falling state.

  FIG. 3 shows a state transition diagram of the digital video camera 100 according to the falling state. In the figure, “falling” and “waiting for stability” are falling states, and “idle” and “initial state” are non-falling states. When a predetermined time elapses in the initial state, the state transits to the idle state. In the idle state, when a fall is detected from the history information of acceleration or acceleration change applied to the digital video camera 100 at the present time, a transition is made to the fall state. In this fall state, when a predetermined time elapses, a transition is made to a stabilization wait state. Even when waiting for stability, if a fall is detected from the history information of acceleration or acceleration change, the fall state is restored. In addition, when a predetermined time elapses without detecting a fall in the stabilization waiting state, the state transits to the idle state.

  FIG. 4 shows a processing procedure for performing drop detection control of the digital video camera 100 in the form of a flowchart.

  The control unit 101 starts a fall detection process defined separately (step S1). When a state change is detected by the activated fall detection process (step S2), the state change is notified (step S3).

  When the digital video camera 100 changes from the non-falling state to the falling state, the control unit 101 interrupts the data recording operation on the hard disk, for example, and retracts the head from the disk. Conversely, when the fall state recovers from the non-fall state, the retracted head is returned to the disk, and the interrupted data recording operation is resumed.

  In the fall detection process in step S1, a method (previously described) is applied that predicts the state in which the device is starting to fall freely using both the gravitational acceleration detected from the acceleration sensor at the time of fall and the history of acceleration change. ing. Here, it is known that gravity varies depending on the latitude on the earth, and if the difference in gravity depending on the place where the device is used, that is, the latitude, that is, the standard gravity determined according to the latitude is not considered, An accurate fall state cannot be predicted.

  Therefore, in this embodiment, an appropriate fall detection operation is performed according to the standard gravity determined based on the latitude information of the current location acquired from the GPS receiver 160. In this way, when the falling state is detected more accurately, it is possible to perform an operation in preparation for an impact upon landing such as withdrawing the head of the hard disk drive at an appropriate timing.

  For example, when the fall detection process in step S1 in FIG. 4 is operated at a certain cycle, the fall detection control parameter is sequentially changed based on the latitude information obtained from the GPS reception signal or the like for each cycle. The same fall detection accuracy can be maintained even when in the South Pole or on the equator.

  FIG. 5 shows a detailed procedure of the drop detection process performed in step S1 of the flowchart shown in FIG. 4 in the form of a flowchart. The control unit 101 starts the illustrated process at predetermined intervals.

  First, the control unit 101 performs parameter setting based on the current position information by a separately defined fall detection control parameter setting process (step S11).

  Next, the control unit 101 calculates a composite value Gavg from the acceleration (Gx, Gy, Gz) information input from the triaxial acceleration sensor using the above equation (1) (step S12). Then, the control unit 101 records the calculated combined value Gavg in the built-in memory 118 together with the accelerations (Gx, Gy, Gz) corresponding to the three orthogonal axes.

  Next, the control unit 101 applies the “filter suspected to be 0G” to the acceleration change history information recorded in the built-in memory 118, and the acceleration Gavg detected for the past A cycles from the present is determined to be 0G. It is checked whether or not the threshold value P has fallen even once (step S13). Here, when the acceleration Gavg has not fallen below the 0G determination threshold value P over the past A cycle, a determination result of non-falling is returned (step S18), and this processing routine is ended.

  If the acceleration Gavg has fallen below the 0G discrimination threshold P even once during the past A cycle by applying the “filter suspected to be 0G”, the control unit 101 subsequently applies the “swing up filter”. Then, it is checked whether the acceleration Gavg for the past B cycles has exceeded the swing-up threshold value Q even once from the present (step S14). Here, when the acceleration Gavg detected over the past B cycles exceeds the swing-up threshold Q even once, a determination result of non-falling is returned (step S18), and this processing routine is ended.

  If the acceleration Gavg detected during the past B cycle has never exceeded the swing-up threshold Q by applying the “swing-up filter”, the control unit 101 subsequently applies the “swing-down filter”. Thus, it is checked whether the acceleration Gavg for the past C cycles is swung down from the present (acceleration noise) threshold R even once (step S15). Here, when the acceleration Gavg detected over the past C cycles has exceeded the threshold value R even once, the determination result of non-falling is returned (step S18), and this processing routine is terminated.

  When applying the “down swing filter” and the acceleration Gavg detected during the past C cycle has never exceeded the swing down threshold R, the control unit 101 subsequently selects the “free fall filter”. Applying it, it is checked whether or not the acceleration Gavg for the past D cycles has exceeded the drop determination threshold value S even once from the present (step S16).

  When the “free fall filter” is applied and the acceleration Gavg detected during the past D cycles has never exceeded the drop determination threshold S, the control unit 101 returns a determination result of non-falling. (Step S18), this processing routine is terminated.

  On the other hand, when the acceleration Gavg detected during the past D cycle exceeds the drop determination threshold value S even once, the control unit 101 returns a determination result of drop (step S17), and this process End the routine.

  The contents of each filter applied in steps S13 to S16 are summarized in the following table.

  When the falling state of the digital video camera 100 is detected in accordance with the processing procedure shown in FIG. 5, the control unit 101 suspends the data recording operation on the hard disk and evacuates the head from the disk. The operation for suppressing the influence of the impact on the motor is executed. Conversely, when the fall state recovers from the non-fall state, the retracted head is returned to the disk, and the interrupted data recording operation is resumed.

  FIG. 6 shows, in the form of a flowchart, the procedure for setting the fall detection control parameter based on the position information, which is executed in step S11 of the flowchart shown in FIG.

  When the current position information is acquired from the GPS receiver 160 (step S21), the control unit 101 sets the value of the fall detection control parameter based mainly on the latitude information among the current position information (step S22).

  The drop detection control parameters referred to here are specifically the threshold values P, Q, R, and S of each filter applied in steps S13 to S16 in the flowchart shown in FIG. The threshold values of the filters set based on the latitude information are summarized in Table 2 below.

  The fall detection control parameter values as shown in Table 2 are stored in the nonvolatile memory 142, for example. In step S22, each drop detection control parameter value corresponding to the latitude information may be read from the nonvolatile memory 142 and set as a threshold value for each filter.

The detection signal of the acceleration sensor 150 can be input in an analog manner or digitally. FIG. 7 schematically shows a functional configuration for realizing the fall detection control when the detection signal of the acceleration sensor 150 is input in an analog manner. FIG. 8 schematically shows a functional configuration for realizing the fall detection control when the detection signal of the acceleration sensor 150 is digitally input. In the former case, when the analog detection signal of the acceleration sensor 150 is digitally converted by an AD converter and the acceleration calculation unit acquires this digital signal through the AD converter device driver, the acceleration Gavg is calculated based on the above equation (1). . In the latter case, the acceleration sensor 150 digital detection signal can be taken into the system via a digital interface circuit such as I ² C, and the acceleration calculation unit can transmit the digital signal through the digital interface device driver. When the signal is acquired, the acceleration Gavg is calculated based on the above equation (1).

  7 and 8, the acceleration calculation unit, the fall state determination unit, the GPS reception control unit, and the device driver can be implemented as program codes executed by the control unit 101. The GPS reception control unit obtains current position information such as latitude information by inputting the detection signal received from the GPS satellite by the GPS receiver 160 by analog input or digital input in the same manner as described above. Then, the fall state determination unit reads the fall detection control parameter corresponding to the latitude information from the nonvolatile memory 142 and sets it as a threshold value in each filter, and then drops the digital video camera 100 according to the processing procedure shown in FIG. Determine the state.

  The present invention has been described in detail above with reference to specific embodiments. However, it is obvious that those skilled in the art can make modifications and substitutions of the embodiment without departing from the gist of the present invention.

  In the present specification, an embodiment applied to a digital camera has been described. However, the gist of the present invention is not limited to this, and the present invention can be applied to various types of information devices.

  Further, in the present specification, the description has been made mainly with the hard disk drive as the recording medium, but the gist of the present invention is not limited to this, and there are various types of devices that need to be prevented from being destroyed when dropped. The present invention can be similarly applied to information equipment equipped with a type of recording medium. The recording media may be distinguished as being built-in or removable.

  In short, the present invention has been disclosed in the form of exemplification, and the description of the present specification should not be interpreted in a limited manner. In order to determine the gist of the present invention, the claims should be taken into consideration.

FIG. 1 is a diagram schematically showing the configuration of the digital video camera 100. FIG. 2 is a diagram schematically showing the configuration of the personal computer 200. FIG. 3 is a diagram showing a state transition diagram of the digital video camera 100 according to the falling state. FIG. 4 is a flowchart showing a processing procedure for performing drop detection control of the digital video camera 100. FIG. 5 is a flowchart showing a detailed procedure of the drop detection process performed in step S1 of the flowchart shown in FIG. FIG. 6 is a flowchart showing a procedure of setting processing of the fall detection control parameter based on the position information. FIG. 7 is a diagram schematically illustrating a functional configuration for realizing the fall detection control when the detection signal of the acceleration sensor 150 is input in an analog manner. FIG. 8 is a diagram schematically illustrating a functional configuration for realizing the fall detection control when the detection signal of the acceleration sensor 150 is digitally input.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Digital video camera 101 ... Control part (CPU)
DESCRIPTION OF SYMBOLS 102 ... Camera function part 111 ... Optical lens part 112 ... Photoelectric conversion part 113 ... Image signal processing part 114 ... Image input / output part 115 ... Liquid crystal display 116 ... Audio | voice input / output part 117 ... Audio | voice signal processing part 118 ... Built-in memory (RAM)
119 ... Built-in memory (ROM)
DESCRIPTION OF SYMBOLS 120 ... Operation input part 131 ... Communication part 132 ... Drive 141 ... Power supply 142 ... Non-volatile memory 150 ... Sensors 160 ... GPS receiver 200 ... Personal computer 201 ... CPU
202 ... ROM
203 ... RAM
204 ... Local bus 205 ... Bridge 206 ... Input / output bus 207 ... Input / output interface 208 ... Keyboard 209 ... Pointing device (mouse)
210 ... Display 211 ... HDD
214 ... Connection port 221 ... Removable recording medium 222 ... External connection device 230 ... Sensors 240 ... Non-volatile memory 250 ... Power supply 260 ... GPS receiver

Claims (6)

A data recording device for recording data on a recording medium,
Acceleration detecting means for detecting acceleration applied to the device;
Position information acquisition means for acquiring the current position of the device;
According to the current position acquired by the position information means, the fall detection control parameter for detecting the fall of the apparatus is switched based on the acceleration detected by the acceleration detection means and the history of acceleration change, and the apparatus A fall state judging means for judging the fall state of
A preventive operation control means for executing an operation for preventing the destruction of the recording medium according to a determination result of the fall state of the apparatus by the fall state determination means;
A data recording apparatus comprising: The recording medium is a type of recording medium in which a read / write head seeks a predetermined recording position on a recording surface to perform data recording,
The prevention operation control means prevents the recording medium from being destroyed by retracting the read / write head from the recording surface when the fall prediction means predicts the fall of the apparatus.
The data recording apparatus according to claim 1, wherein: The acceleration detecting means is composed of a three-axis acceleration sensor corresponding to three orthogonal axes of the X axis, the Y axis, and the Z axis, which are provided in the apparatus.
The fall state determination means periodically inputs acceleration (Gx, Gy, Gz) information detected by the three-axis acceleration sensor and records it in a built-in memory, and three orthogonal axes of the X, Y, and Z axes. A combined value Gavg of acceleration (Gx, Gy, Gz) information calculated as a sum of squares of acceleration values corresponding to is calculated and recorded in the built-in memory, and is input to the built-in memory and the input value from the triaxial acceleration sensor. Determining whether the device is in a fall state based on the recorded acceleration history information;
The data recording apparatus according to claim 1, wherein: A memory for storing a threshold value corresponding to latitude information for detecting a fall from a history of acceleration and acceleration change;
The fall state determination means reads a threshold value corresponding to the position information of the device acquired by the position information means from the memory, and determines the fall state of the device using the threshold value.
The data recording apparatus according to claim 1, wherein: A method of controlling a data recording apparatus for recording data on a recording medium,
An acceleration detecting step for detecting an acceleration applied to the data recording device and a history of acceleration changes based on an output of an acceleration sensor provided in the data recording device;
A position information acquisition step of acquiring the current position of the device;
According to the current position acquired in the position information acquisition step, the fall detection control parameter for detecting the fall of the device is switched based on the acceleration detected by the acceleration detection step and the history of acceleration change, and the A fall state determination step for determining a fall state of the device;
A preventive operation control step for executing an operation for preventing destruction of the recording medium in response to the prediction of the fall of the apparatus by the drop predicting step;
A method for controlling a data recording apparatus comprising: A computer program written in a computer-readable format so as to execute a process for controlling a data recording apparatus for recording data on a recording medium on the computer, the computer comprising:
Acceleration detecting means for detecting an acceleration applied to the data recording device and a history of acceleration changes based on an output of an acceleration sensor equipped in the data recording device;
Position information acquisition means for acquiring the current position of the device;
According to the current position acquired by the position information means, the fall detection control parameter for detecting the fall of the apparatus is switched based on the acceleration detected by the acceleration detection means and the history of acceleration change, and the apparatus A fall state judging means for judging the fall state of
A preventive operation control means for executing an operation for preventing the destruction of the recording medium according to a determination result of the fall state of the apparatus by the fall state determination means;
Computer program to function as

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