JP2004206768A - Hard disk drive mounted type portable device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hard disk drive mounted type portable device capable of preventing the occurrent of offtrack and the reduction of a transfer rate caused by external rotational disturbances, and suppressing the self-excited vibration of an incorporated hard disk drive. <P>SOLUTION: A disk movable section 22 is freely rotatively supported on the main body 2 of the portable device via a bearing 21. In the movable section 22, a hard disk drive 19 is positioned and fixed so that the center of a bearing 36 is identical with the shaft 24 of the center of the movable section 22. Then, a dummy weight 39 is added to the movable section 22 so that the position of a center of gravity on the dual axis of the entire free rotating body including the movable section 22. Thus, the occurrence of offtrack caused by external rotational disturbances is prevented. Additionally, the rotation of the movable section 22 is regulated by a brake mechanism 38 during seeking. Thus, self-excited vibration caused by the seeking operation of the hard disk drive 19 is suppressed. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a portable device, such as a digital video camera recorder, of a type equipped with a hard disk drive as an information storage medium.
[0002]
[Prior art]
A portable device such as a digital video camera recorder that handles a large amount of data such as a moving image or a still image is equipped with a lightweight and large-capacity data recording device. 2. Description of the Related Art In recent years, large-capacity and small-sized hard disk drives have become widespread due to improvement in recording density, and have come to satisfy conditions suitable for practical use in portable devices such as digital video cameras.
[0003]
However, when a hard disk device is mounted on a portable device, how to prevent off-track from occurring when an HSA (Head Stack Assembly) in the hard disk drive is disturbed by vibration becomes an important issue.
[0004]
If off-track occurs frequently, the frequency of data recording / reproducing errors will increase, and the data transfer rate will decrease. In particular, in the case of a digital video camera recorder, high-quality moving image recording cannot be performed, for example, a cache overflow occurs due to a decrease in a data transfer rate at the time of recording moving image data and a frame is dropped.
[0005]
The principle that the off-track of the hard disk drive is generated by disturbance will be described below. The mechanism inside the hard disk drive will be described with reference to FIG. The hard disk drive 51 has a rectangular box-shaped case 52. A disk (platter) 53, which is a disk-shaped storage medium having magnetic recording layers provided on both sides in a case 52, a spindle motor (SPM) 54 as a disk drive mechanism for supporting and rotating the disk 53, HSA (Head Stack Assembly) 55 is disposed. The HSA 55 includes an HGA (Head Gimble Assembly) 56 having a magnetic head slider having a head as an element for reading and writing signals to and from the disk 53 at the tip, a plurality of arms 57 supporting the HGA 56 at the tip, and A pivot bearing 58 rotatably supports the arm 57 so as to move along the surface of the disk 53, and a voice coil motor (VCM) 59.
[0006]
When an electric current is applied to the voice coil motor 59, the HSA 55 rotates about the pivot bearing 58 by the force of the magnetic field generated between the voice coil motor 59 and a magnet disposed outside. By the rotation of the HSA 55, the head is moved (seeked) in the radial direction of the disk 53, and positioned (tracked) on a target track on the disk 53.
[0007]
In the hard disk drive 51, the track pitch has become narrower than 1 μm due to the improvement in recording density, and it is necessary to accurately position the head (for example, with a 10 nm accuracy) in that narrow range.
[0008]
Normally, the center of gravity of the HSA is accurately positioned at the center of rotation of the pivot bearing 58, so that, for example, even if disturbance vibration is applied in the X-axis or Y-axis direction in FIG. And the force for rotating the HSA 55 is hardly generated.
[0009]
However, it is vulnerable to disturbance in the rotational direction, and in particular, when it is subjected to a rotational disturbance having the rotation center of the pivot bearing 58 as an axis, offtrack is likely to occur due to the influence (for example, see Patent Document 1). ).
[0010]
[Patent Document 1]
JP-A-7-176180 (paragraph number [0008], FIG. 1).
[0011]
[Problems to be solved by the invention]
FIGS. 11 to 14 show the results of experimentally summarizing the off-track phenomenon.
[0012]
FIGS. 11 to 13 show experimental results in the case of applying linear motion in the X-axis, Y-axis, and Z-axis directions as disturbances. The acceleration of the linear vibration is set to 0.3 G, the frequency is changed in the range of 5 Hz to 500 Hz, and the measurement result of the transfer rate for each data zone on the disk is shown on the vertical axis. FIG. 14 shows an experimental result in the case where the vibration in the rotation direction was applied. The vibration frequency was 15 Hz, the angular displacement was 0.2 °, and the angular acceleration α was varied in the range of 0 to about 80. The results of measuring the transfer rate for each data zone on the disk each time are shown on the vertical axis.
[0013]
As can be seen from these tables, when linear vibration is applied, the transfer rate hardly decreases over a wide range of frequencies, and off-track hardly occurs. On the other hand, when receiving rotational vibration, the transfer rate is greatly reduced, and it is considered that many off-tracks are occurring.
[0014]
When a hard disk drive is incorporated in a stationary device such as a desktop PC, it is unlikely that the hard disk drive will be affected by disturbance in the rotation direction. However, when a hard disk drive is incorporated in a portable device such as a digital video camera recorder, for example, camera shake at the time of shooting or the like may cause a rotational disturbance to cause off-track. As described above, the off-track problem due to the rotational disturbance can be said to be a problem unique to the portable device.
[0015]
We estimated the effect of the rotational disturbance on off-track by simulation. The result is shown in FIG. In this graph, the vertical axis represents the ratio (%) of the deviation between the center of the head gap and the track center to the track pitch, and the horizontal axis represents the total number of read servo frames corresponding to the elapsed time. A state in which the amount of deviation between the center of the gap of the head and the center of the track is within 20% of the track pitch is defined as on-track, and a deviation from this range is defined as off-track. The line A indicates the waveform of the rotational vibration, and the line B indicates the change in the amount of displacement between the center of the head gap and the center of the track due to the rotational vibration. As described above, when the rotational disturbance is applied to the hard disk drive, a situation frequently deviating from the on-track range occurs, and it has been confirmed that the transfer rate is reduced.
[0016]
In order to suppress such rotational vibration of the hard disk drive, a method of elastically suspending the hard disk drive from a direction horizontal to the disk surface by a buffer member such as a spring in a portable device can be considered. However, when such an elastic suspension structure is employed, it is difficult for vibrations to be transmitted from the outside to the internal hard disk drive, but it is difficult for vibrations generated in the hard disk drive itself to escape to the outside. This is because the HSA causes a rapid change in angular velocity during a seek, and the change in angular momentum caused by the sudden change in angular velocity induces self-excited vibration, and when self-excited vibration occurs, the vibration lasts for a long time. Means Due to this vibration, the stabilization of the HSA after the seek is not completed quickly, and it takes a long time to complete the seek command.
[0017]
The graph of FIG. 16 shows a comparison between the results of the measurement of the seek command completion time when the buffer member was used and when it was not used by the experiment. When the cushioning member is used, the self-excited vibration occurs as described above, so that the seek command completion time becomes long and the transfer rate decreases.
[0018]
The present invention has been made in view of such circumstances, and can prevent the occurrence of off-track and a decrease in transfer rate due to rotational disturbance, and can suppress self-excited vibration of a built-in hard disk drive. It aims to provide on-board portable devices.
[0019]
[Means for Solving the Problems]
In order to solve such a problem, a portable device equipped with a hard disk drive according to the present invention includes a movable unit having a main body of the portable device and a shaft rotatably connected to the main body of the portable device at a rotation center. A rotatable arm that supports the head and moves the head along the surface of the disk, and is positioned on the movable part such that the center of rotation of the movable part coincides with the center of rotation of the arm. And a mounted hard disk drive.
[0020]
According to the present invention, even when the main body of the digital video camera recorder generates rotational vibration, the hard disk drive does not move following the rotational vibration due to inertia. Therefore, it is possible to effectively prevent the occurrence of off-track due to the rotational disturbance of the hard disk drive and the reduction of the data transfer rate.
[0021]
In the portable device equipped with a hard disk drive according to the present invention, a dummy weight is provided for aligning the center of gravity of the movable portion with the hard disk drive with the center of the shaft portion. Thus, for example, even when the rotation center of the arm is not located at the position of the center of gravity of the hard disk drive, the center of gravity of the movable unit on which the hard disk drive is mounted and the rotation center of the movable unit can be matched.
[0022]
Further, in the portable device equipped with the hard disk drive of the present invention, by providing the brake mechanism for restricting the rotation of the movable portion during the seek, the self-excited vibration caused by the seek operation of the hard disk drive can be suppressed.
[0023]
Further, by predicting the seek amount and controlling the brake mechanism to operate only when the predicted seek amount is larger than a preset value, the life extension and power saving due to the wear deterioration of the brake mechanism are achieved. In addition to the fact that the time during which the movable portion is free to rotate can be lengthened in total, it is possible to sufficiently secure the effective period of resistance to rotational disturbance.
[0024]
Furthermore, a dummy rotator that is rotatably arranged coaxially with the axis of the movable part so as to generate rotational inertia in the movable part, a drive mechanism that drives the dummy rotator, and an angular momentum generated during a seek of the hard disk drive. Control means for controlling the driving of the dummy rotator by the driving mechanism so that the change in the angular momentum that cancels the change is generated by the rotation of the dummy rotator, whereby the angular momentum in the free rotator including the movable part is added. Is substantially zero, and it is possible to suppress self-excited vibration of the hard disk drive caused by a rapid change in angular momentum.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0026]
FIG. 1 is a perspective view showing an external appearance of a digital video camera recorder as a portable electronic device according to an embodiment to which the present invention is applied and a configuration of a main part of the invention.
[0027]
This digital video camera recorder 1 has a main body 2 having a shape and size that can be operated by a user with one hand. The main body 2 is provided with a lens unit 3, an LCD (Liquid Crystal Display) panel 4, and various operation buttons and switches (not shown). The LCD panel 4 displays a subject being photographed, an image reproduced from a hard disk drive 19 as a built-in storage medium, and further displays information necessary for operating the digital video camera recorder 1.
[0028]
FIG. 2 shows an electrical configuration of the digital video camera recorder 1.
The lens unit 3 and the CCD (Charge Coupled Device) 11 constitute an imaging unit. The lens unit 3 performs an automatic aperture control operation and an automatic focus control operation according to a control signal from the CPU 20. The output signal of the CCD 11 is converted to a digital video signal by the A / D converter 12 and then sent to the video signal processing unit 13.
[0029]
The video signal processing unit 13 generates a digital component signal including a luminance signal and a color difference signal from the digital video signal, and supplies the digital component signal to the memory controller 14. The display signal processing unit 15 and the bus 10 of the CPU 20 are connected to the memory controller 14. The display signal processing unit 15 generates the RGB signals by processing the component signals, and outputs the RGB signals to the LCD panel 4.
[0030]
The bus 10 is connected to a buffer memory 16 such as a DRAM (Dynamic Random Access Memory), a CPU 20, a video compression encoding / decoding unit 17, and a hard disk controller 18.
[0031]
The video compression encoding / decoding unit 17 compresses or decompresses a still image using, for example, JPEG (Joint Photographic Experts Group) or compresses or decompresses a moving image using MPEG (Moving Picture Experts Group). The hard disk controller 18 interprets a control command from the CPU 20 and controls data recording and reproduction with respect to the hard disk drive 19. The CPU 20 receives an operation signal from an operation button or switch provided on the main body 2 and sends a command for executing the operation to the imaging unit, the memory controller 14, the video compression encoding / decoding unit 17, the hard disk controller 18, and the like. Run against
[0032]
Next, an operation of photographing an image by the digital video camera recorder 1 and recording the image in the hard disk drive 19 as a built-in storage medium will be described.
[0033]
Video data such as a still image or a moving image captured by the imaging unit and processed by the video signal processing unit 13 is stored in the buffer memory 16 under the control of the memory controller 14. When a certain amount of video data is stored in the buffer memory 16, the video data is compression-encoded by the video compression encoding / decoding unit 17 under the control of the CPU 20 and stored in the buffer memory 16.
[0034]
Thereafter, the compression-encoded video data is read from the buffer memory 16 under the control of the CPU 20, and is converted into a file in a format operable by a predetermined file system. Then, the CPU 20 sends a write command to the hard disk controller 18. Upon receiving the write command, the hard disk controller 18 takes in the video file from the buffer memory 16 via the bus 10 and controls to record the video file on the hard disk drive 19.
[0035]
When reproducing the video data recorded in the hard disk drive 19, a read command including the name of the file to be reproduced is given from the CPU 20 to the hard disk controller 18. Upon receiving the read command, the hard disk controller 18 controls to read the corresponding file from the hard disk drive 19 according to the file system, and transfers the data of the file read from the hard disk drive 19 to the buffer memory 16 via the bus 10. .
[0036]
Thereafter, under the control of the CPU 20, video data is read from the buffer memory 16, and the read video data is decompressed and decoded by the video compression encoding / decoding unit 17 and returned to the buffer memory 16. Further, under the control of the CPU 20, the memory controller 14 reads the decoded video data from the buffer memory 16, transfers the read video data to the display signal processing unit 15, and displays the data on the LCD panel 4.
[0037]
The digital video camera recorder 1 employs a hard disk drive 19 as a built-in storage medium. In this case, as described above, there is a problem that off-track is likely to occur due to rotational vibration applied to the main body 2 of the digital video camera recorder 1, and in order to solve this problem, the following structure is adopted. . FIGS. 3 and 4 show a suspension structure of the hard disk drive 19 in the digital video camera recorder 1 of the present embodiment. FIG. 3 is a side view as viewed from a direction perpendicular to the disk surface, and FIG. 4 is a side view as viewed from a direction along the disk surface.
[0038]
A disk-shaped movable portion 22 is rotatably supported on the main body 2 of the digital video camera recorder 1 via a bearing 21. A shaft 24 rotatably supported by the bearing 21 is fixedly provided at the center of the movable portion 22. Therefore, the movable portion 22 is in a free rotation state about the center shaft 24 as a rotation center.
[0039]
The hard disk drive 19 is fixedly mounted on the movable part 22 with a fixture such as a screw. The hard disk drive 19 has a rectangular box-shaped case 31. A disk (platter) 23 which is a disk-shaped storage medium provided with magnetic recording layers on both sides in a case 31, a spindle motor (SPM) 32 as a disk drive mechanism for supporting and rotating the disk 23, An HSA (Head Stack Assembly) 33 is provided. The HSA 33 has an HGA (Head Gimble Assembly) having a magnetic head slider mounted with a head as an element for reading and writing a signal to and from the disk 23 at the front end, a plurality of arms 35 supporting the HGA at the front end, and It comprises a pivot bearing 36 that rotatably supports the arm 35 so as to move along the surface of the disk 23, and a voice coil motor (VCM) 37. The case 31 has a printed circuit board (not shown) on which a spindle motor (SPM) 32, a voice coil motor (VCM) 37, a controller for controlling the head, a memory, a hard disk controller, and other circuits are mounted. Is installed.
[0040]
Here, the mounting position of the hard disk drive 19 is set so that the pivot bearing 36 is arranged at a position coaxial with the shaft 24 at the center of the movable portion 22. Therefore, the position on the two axes of the center of gravity of the hard disk drive 19 (on the XY axis shown in FIG. 1) is located at a position deviated from the center (center of rotation) of the movable part 22. Therefore, a dummy weight 39 is provided on the movable part 22 so that the center of gravity of the movable part 22 on the two axes of the entire free rotating body including the movable part 22 becomes the center of the movable part 22. The dummy weight 39 may be attached to either surface of the movable section 22.
[0041]
Further, the movable portion 22 is provided with a brake mechanism 38 for suppressing its rotation. As the brake mechanism 38, for example, a mechanism that contacts or separates at one point or a plurality of points with respect to a peripheral surface or a flat side surface of the disk-shaped movable portion 22 and restricts rotation of the movable portion 22 by contact friction is used. A solenoid, a motor, or the like is used as a power source for moving the pad in contact with the movable portion 22, and turning on and off of power to the power source is controlled by the CPU 20 of the digital video camera recorder 1.
[0042]
Due to the suspension structure of the hard disk drive 19, in a state where the rotation of the movable part 22 is not restricted by the brake mechanism 38, even if the main body 2 of the digital video camera recorder 1 generates rotational vibration, the hard disk drive 19 rotates by inertia. It does not move following the vibration. Therefore, it is possible to effectively prevent the occurrence of off-track due to the disturbance of the rotation of the hard disk drive 19 and the reduction of the data transfer rate.
[0043]
Next, control of the brake mechanism 38 will be described.
[0044]
As shown in the timing chart of FIG. 5, the CPU 20 sets the brake mechanism 38 to the on state and outputs the seek command to the hard disk controller 18 until the seek completion command is received from the hard disk controller 18. The rotation is restricted, and the brake mechanism 38 is controlled to be off during other periods to set the movable part 22 in a rotation-free state. As described above, while the seek operation is being performed by the hard disk drive 19, the rotation of the movable portion 22 is kept in a restricted state, whereby the self-excited vibration caused by the seek operation of the hard disk drive 19 can be suppressed.
[0045]
By the way, in the case of a seek in which the seek amount is small as in the case where the adjacent track is continuously read, the change in the angular momentum is small, and the substantial effect of the self-excited vibration on the transfer rate is within a negligible range. Therefore, it is desirable to perform brake operation control using the seek amount as a parameter. Specifically, a value of the seek amount accompanying the brake operation is set, a seek amount for the next disk access is calculated, and if the seek amount is equal to or more than the above value, control is performed so as to activate the brake. Good. By prohibiting the unnecessary operation of the brake in this manner, it is possible to extend the life and reduce power consumption due to wear and deterioration of the brake mechanism 38. Further, since the rotation free time of the movable portion 22 can be lengthened in total, it is possible to sufficiently secure the effective period of the resistance to the rotational disturbance.
[0046]
Next, another embodiment of the present invention will be described.
[0047]
In this embodiment, a change in angular momentum that cancels a change in angular momentum that occurs during a seek operation of a hard disk drive is generated in a free rotating body including a movable part, so that the angular momentum in the free rotating body including the movable part is reduced. The change is made substantially zero in total.
[0048]
6 and 7 show specific examples. In the movable section 22, a dummy rotating body 41 having a rotational inertia (moment of inertia) equivalent to the rotational inertia of the HSA 33 in the hard disk drive 19 is provided at a position coaxial with the pivot bearing 36 of the HSA 33. It is possible to rotate as a center. The rotating body 41 is driven by a driving mechanism, and a control signal is sent from the CPU 20 to the driving mechanism to control the rotation direction and the speed. As an example of the driving mechanism, a voice coil motor 42 can be used similarly to the HSA 33 in the hard disk drive 19.
[0049]
FIG. 8 shows an electrical configuration of the digital video camera recorder 1 of this embodiment. A speed control signal from the CPU 20 is supplied to a driver circuit 43 for driving the voice coil motor 42.
[0050]
The control of the rotating body 41 is performed as follows. When issuing a seek command to the hard disk controller 18, the CPU 20 determines the angular velocity, which is a target value of the angular velocity at each time, for canceling the change in the angular momentum occurring during the current seek of the hard disk drive 19 based on the seek amount. Ask for a profile. A speed control signal is output from the CPU 20 to the driver circuit 43 so as to drive the dummy rotator 41 according to the angular speed profile.
[0051]
At this time, a speed servo is performed. A circuit for detecting a back electromotive force generated by passing a current through the coil of the voice coil motor 42 is added, an actual angular velocity is estimated from the detected back electromotive force, and a driver circuit 43 is provided based on the speed estimation result. Of the speed control signal supplied to the controller.
[0052]
In this manner, as shown in FIG. 9, the change in angular momentum that cancels the change in angular momentum that occurs at the time of seeking of the hard disk drive 19 is generated in the free rotating body including the movable portion 22, so that the free rotation including the movable portion 22 is performed. The change in the angular momentum of the rotating body becomes substantially zero, and the self-excited vibration of the hard disk drive 19 caused by the rapid change in the angular momentum can be suppressed.
[0053]
It should be noted that the hard disk drive-mounted portable device of the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the spirit of the present invention.
[0054]
【The invention's effect】
As described above, according to the present invention, when a hard disk drive is incorporated as a built-in storage medium of a portable electronic device such as a digital video camera recorder, the occurrence of off-track due to rotational disturbance and a decrease in transfer rate are prevented. And the self-excited vibration of the built-in hard disk drive can be suppressed.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an external appearance of a digital video camera recorder as a portable electronic device according to an embodiment to which the present invention is applied and a configuration of a main part of the invention.
FIG. 2 is a block diagram showing an electrical configuration of the digital video camera recorder of FIG.
FIG. 3 is a side view of the suspension structure of the hard disk drive in the digital video camera recorder of FIG. 1 as viewed from a direction perpendicular to the disk surface.
FIG. 4 is a side view of the suspension structure of the hard disk drive in the digital video camera recorder of FIG. 1 as viewed from a direction along a disk surface.
FIG. 5 is a timing chart showing control of a brake mechanism based on a seek.
FIG. 6 is a side view of a suspension structure of a hard disk drive in a digital video camera recorder according to another embodiment of the present invention viewed from a direction perpendicular to a disk surface.
7 is a side view of the suspension structure of the hard disk drive in the digital video camera recorder of FIG. 6, viewed from a direction along the disk surface.
8 is a block diagram showing an electrical configuration of the digital video camera recorder of FIG.
FIG. 9 is a timing chart showing a relationship between a change in angular momentum in the hard disk drive and a change in angular momentum of the free rotating body.
FIG. 10 is a plan view showing an internal mechanism of a general hard disk drive.
FIG. 11 is a graph showing a correlation between the linear motion of the X-axis and a decrease in the transfer rate.
FIG. 12 is a graph showing a correlation between a Y-axis linear vibration and a decrease in transfer rate.
FIG. 13 is a graph showing a correlation between the linear motion of the Z axis and a decrease in the transfer rate.
FIG. 14 is a graph showing a correlation between rotational vibration and transfer rate reduction.
FIG. 15 is a diagram showing a result of simulating the influence on off-track due to rotational disturbance.
FIG. 16 is a graph showing the results of measuring seek command completion times when a buffer member is used and when it is not used.
[Explanation of symbols]
1 Digital Video Camera Recorder 2 Main Body 18 Hard Disk Controller 19 Hard Disk Drive 20 CPU
21 Bearing 22 Movable part 23 Disk 24 Shaft 33 HSA
35 Arm 36 Pivot bearing 38 Brake mechanism 39 Dummy weight 41 Dummy rotating body 42 Voice coil motor 43 Driver circuit

Claims (5)

The body of the mobile device,
A movable portion having, at the center of rotation, a shaft portion rotatably connected to the main body of the portable device;
A rotatable arm for supporting the head and moving the head along the surface of the disk is mounted and positioned on the movable part such that the center of rotation of the movable part coincides with the center of rotation of the arm. And a hard disk drive. A portable device equipped with a hard disk drive according to claim 1,
A portable device mounted with a hard disk drive, further comprising a dummy weight for aligning a center of gravity of the movable portion on which the hard disk drive is mounted with a center of the shaft portion. A portable device equipped with a hard disk drive according to claim 1,
A portable device equipped with a hard disk drive, comprising a brake mechanism for restricting rotation of the movable portion during a seek. A hard disk drive-mounted portable device according to claim 3, wherein
A portable device mounted with a hard disk drive, further comprising means for predicting a seek amount and controlling the brake mechanism to operate when the predicted seek amount is larger than a preset value. A hard disk drive-mounted portable device according to claim 3, wherein
A dummy rotator that is rotatably disposed coaxially with a shaft of the movable unit so as to generate rotational inertia in the movable unit,
A drive mechanism for driving the dummy rotating body,
The hard disk drive further includes control means for controlling the driving of the dummy rotator by the drive mechanism so as to generate a change in angular momentum by the rotation of the dummy rotator, which cancels a change in angular momentum that occurs during a seek of the hard disk drive. A portable device equipped with a hard disk drive.

Images