JP4202011B2 - Disk drive device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a disk drive device that suppresses surface vibration, deformation, and tilt that occur when a disk rotates, and in particular, a CD-ROM, CD-R, CD-RW, DVD, DVD-ROM, DVD-RW, and the like. The present invention relates to a high-speed rotating disk drive device that uses laser light for reading and writing data.
[0002]
[Prior art]
In recent years, demands for speeding up CD-ROMs, DVD drives, and the like have become stricter, and high-speed operation reaching a critical rotational speed has been performed. The critical rotational speed is a rotational speed at which the backward natural frequency swinging in the direction opposite to the rotational direction of the disk becomes 0 Hz. The disk is generally unstable at this rotational speed, and is easily deformed and vibrated easily by the influence of disturbance. In order to avoid such problems, it is desirable to design while avoiding the critical rotational speed.
[0003]
The specific value of the critical rotational speed is as follows when taking a CD-R disc, which is a polycarbonate resin disk having a diameter of 12 cm and a thickness of 1.2 mm, for example. That is, the (0, 2) B mode is about 6000 rpm, the (0, 3) B mode is about 7400 rpm, and the (0, 4) B mode is about 9400 rpm. Here, (n, m) represents the mode shape of the vibration of the disk, and the subscript B represents the natural vibration of the backward swing.
[0004]
However, in a CD-ROM, DVD drive or the like that pursues high speed, it is generally necessary to continuously vary the rotational speed in accordance with the access position, so that it is difficult to operate at a critical rotational speed. For example, in a disk drive driven at a maximum speed of 24 times in the ZCLV (Zone Constant Linear Velocity) method, the high-speed side rotational speed is 8350 rpm and the low-speed side rotational speed is about 5000 rpm, and the rotational speed continuously changes within this range. Therefore, reading and writing are performed within a range of rotational speeds including the two critical rotational speeds (0,2) B and (0,3) B described above.
[0005]
For this reason, it is necessary to take measures against deformation and vibration of the disk accompanying rotation around the critical rotation speed. In addition, the medium itself has been changed from a CD-ROM, which has a relatively low recording density, to a DVD-ROM, etc., which requires a higher density and higher reading accuracy. Requests are becoming more demanding. In addition, in recent years, the speed of disk devices capable of writing data, such as CD-R and DVD-RW, has been increased. In writing operations, countermeasures are indispensable because adverse effects such as deformation and vibration are far more serious than reading.
[0006]
Japanese Patent Application Laid-Open No. 2000-57666 discloses a technique that pays attention to the fact that the air flow generated by the rotation of the disk causes vibration. In other words, the top and bottom surfaces of the disc are sandwiched between windage reduction walls with a narrow gap of several mm or less, and a wall is also provided at the end of the disc, so that Reduce the noise and vibration by minimizing the air vortex generated. However, with this method, the structure is slightly complicated and a notch for the spindle motor and pickup is required on the lower surface side of the disk, so turbulence and pressure imbalance occur at this notch. Was the cause of vibration.
[0007]
[Problems to be solved by the invention]
The present invention has been made in consideration of the above-mentioned problems of the prior art, and by devising the internal structure of a disk drive device such as a CD-ROM, DVD, CD-R, DVD-RW, etc. The purpose is to improve the air flow inside the device and suppress the deformation, vibration and tilt of the disk. At that time, the configuration should be as simple as possible. In particular, a disk device capable of writing data even under high-speed rotation conditions including a critical rotation speed is realized.
[0008]
The present invention has been made in order to achieve the above-described problems. A turntable that holds and rotates a disk-shaped disk in a housing, and a disk-shaped disk positioned on the lower side in the rotation axis direction of the disk-shaped disk. A pickup unit for reading and writing signals to and from the top surface and the ground facing the disk-like disk in the vertical direction of the rotation axis of the disk-like disk when the disk-like disk is held and rotated by the turntable. A disk drive device having a side surface, and a rectifying plate constituting a top surface is provided in the housing, and a space between the top surface and the upper surface of the disk-shaped disk, and a ground surface And the bottom surface of the disk-shaped disc are substantially equal, and the ground side surface is provided with a notch or groove for the pickup unit to read and write signals to and from the disk-shaped disc. It is characterized in that the notches or grooves substantially plane symmetrical shape and the disk surface of the notch or groove provided on the surface of the earth-side as symmetrical plane is provided, to accomplish the object by the disk drive unit .
[0009]
The pressure that an operating disk receives from air is usually not the same distribution on the top and bottom surfaces of the disk. For this reason, the disk is pushed down at a portion where the pressure on the upper surface side is relatively high, and the disk is pushed up at a portion where the pressure on the lower surface side is relatively high. This is because the air flow is different between the upper and lower surfaces. Such pressure non-uniformity is a major cause of disk deformation, tilt and vibration. This non-uniform pressure effect is particularly strong at the critical rotational speed where the natural frequency around the back of the disk is 0 Hz.
[0010]
In order to reduce the adverse effects of pressure unevenness, the pressure distribution in the circumferential direction of the disk should be smoothed so that the force applied to the disk surface does not fluctuate locally. The method disclosed in Japanese Patent Laid-Open No. 2000-57666 is an invention based on this technical idea. However, the effect is limited because a notch must be provided in the windage reduction wall on the lower surface side of the disk. In particular, when it is applied to high-speed rotation conditions near the critical rotation speed at which deformation and displacement can be large, the adverse effect of this defect appears strongly and is not necessarily practical.
[0011]
In the present invention, pressure non-uniformity on both sides of the disk is reduced by making the pressure distribution as symmetrical as possible on the upper and lower surfaces of the disk. The reason why the actual pressure distribution is not symmetric is that the shape of the space in the housing is not symmetric on the top and bottom surfaces of the disk. There is a cutout for the pickup part that only exists. Therefore, a notch having substantially the same shape as the ground side surface is provided on the top surface of the disk. Also, the distance from the disk surface to the top surface is made substantially the same as the distance to the ground surface. If necessary, a notched plate may be inserted on the top side as a rectifying plate to ensure symmetry of the spatial shape. Further, CD-ROM drives and the like often have a disk tray. However, the disk tray may be regarded as a ground surface, and the space inside the housing may be designed to be vertically symmetrical. .
[0012]
Moreover, as a form of the notch, a rectangular hole may be cut out or a groove may be formed without making a hole. The hole or groove may continue to the edge of the plate. The effects of the present invention can be obtained if the notches on the top side and the ground side have substantially the same width and length. Of course, the combination of top and bottom or top and bottom and groove is desirable, but due to disk drive design constraints, the top side may be a hole and the ground side may be a groove or vice versa. The effect is obtained.
[0013]
In order to eliminate pressure unevenness on the upper and lower surfaces more completely, not only the vertical space is matched with respect to the distance and notch from the disk surface, but also the disk surface of all the components in other cases It is desirable that the upper and lower sides have the same structure as the symmetry plane. In the case where it is necessary to leave the asymmetry structurally, such as a spindle motor, the shape of the notch may be intentionally made different between the top and the ground in order to eliminate the influence. If an appropriate condition is selected, as a result, a more uneven pressure distribution between the upper and lower surfaces can be obtained, and deformation, inclination, and vibration can be reduced.
[0014]
The present invention realized in this way is particularly effective for a disk on which a signal is written, such as a CD-R / RW or a DVD-RW. This is because writing is more susceptible to the effects of disk deformation, tilting and vibration than reading signals. When the writing operation is performed in the range of 5000 to 10000 rpm, the critical rotational speed included in this range has been a big problem in the prior art. In the disk device of the present invention, since it is effective to suppress deformation, tilt, and vibration in the critical rotational speed range, it can be operated without limiting the rotational speed.
[0015]
In the present invention, the ground side surface and the top surface are referred to by different names depending on the configuration of the disk device. For example, in an apparatus including a disc tray, the ground side surface corresponds to the disc tray. Further, when the device itself is thin, the top surface may coincide with the ceiling portion of the casing case.
[0016]
In any case, of the upper, lower, left and right walls that define the space surrounding the disk in the operating state, the side with the pickup portion is the ground side surface. Even when the ground side surface is composed of a combination of a plurality of parts, they are collectively referred to as a ground side surface. Similarly, the top surface is a wall that forms the opposite side of the disk surface with respect to the disk surface. When the top surface is composed of a combination of a plurality of parts, they are collectively referred to as the top surface. .
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1, 2, 3, and 4. In order to facilitate understanding, in these drawings, components other than those necessary for the description are omitted. In particular, in FIGS. 1 and 3, the image is enlarged and displayed in the vertical direction.
The first embodiment shown in FIG. 1 and FIG. 2 is an example of a CD-ROM or similar device having a structure in which a disk 15 is moved into a casing by a disk tray 13 and is operated on a turntable 18. It is. When the disk 15 is transported, the disk tray 13 slides to the left in FIG. 1, but a notch 14 is formed so that the pickup unit 12 does not get in the way. During the operation of the drive, the notch 14 disturbs the air flow.
[0018]
In order to offset this adverse effect, a rectifying plate 16 is inserted between the disk 15 and the top plate of the housing 11 in the example of FIG. The rectifying plate 16 has a cutout 17 having substantially the same shape as the cutout 14 of the disc tray 13. The positions of the notches 14 and 17 are symmetrical with respect to the surface of the disk 15. More strictly, in consideration of the thickness of the disk 15, it is preferable to install the disk 15 so as to be symmetric with respect to a virtual plane at a position passing through half the thickness. With such a configuration, the pressure distribution on the upper and lower surfaces of the disk 15 becomes substantially equal, and deformation, vibration, and inclination are reduced including the critical rotational speed condition.
[0019]
2 is a side view of FIG. 1. In this figure, A means the distance between the lower surface of the disk 15 and the disk tray 13, and B means the distance between the rectifying plate 16 and the upper surface of the disk 15. A and B are designed to be substantially equal, and together with the effect of providing the notches 14 and 17 at symmetrical positions, contribute to the reduction of vibration, deformation, and inclination.
[0020]
Next, a second embodiment shown in FIGS. 3 and 4 will be described. This embodiment is an example of a structure without a disc tray that serves to carry a disc to a turntable. When the disk 24 is placed on the turntable 22, the bottom plate 27 including the turntable 22 and the pickup unit 23 is pulled out of the casing 21 as it is. Even in such a structure, since the pickup unit 23 moves in the radial direction when accessing the disc, the notch 25 is indispensable in the bottom plate 27, which causes the air flow to be disturbed.
[0021]
For this reason, even in the case of FIG. 3, elements corresponding to the current plate of FIG. 1 are provided. In FIG. 3, instead of inserting the current plate, a wide groove 26 is formed on the inner wall of the top plate 28 of the housing 21 to act as a notch. The groove 26 is provided at a position corresponding to the top and bottom of the notch 25 of the bottom plate 27 in a state where the bottom plate 27 is accommodated in the housing 21. With such a configuration, the pressure distribution on the upper and lower surfaces of the disk 24 becomes substantially equal, and deformation, vibration, and inclination are reduced including the critical rotational speed condition.
[0022]
As shown in FIG. 4, in this example as well, the distance a between the lower surface of the disk 24 and the bottom plate 27 and the distance between the upper surface of the disk 24 and the inner surface of the top plate 28 are designed to be substantially equal. In addition to the effect of providing a notch at the position, it contributes to the reduction of vibration, deformation, and tilt.
[0023]
The present invention is not limited to these two examples. The essence of the invention is to define the configuration of the space around the disk in an operating state in which information is read from and written to the disk, as described in the claims. Even if the size of the housing changes, the effect of the invention remains unchanged.
[0024]
【The invention's effect】
According to the present invention, it is possible to suppress deformation, tilt, and vibration generated in the disk main body by minimal changes that do not cost, such as introduction of a current plate and processing of the top plate.
[0025]
Deformation, tilt, and vibration can be effectively suppressed even under high-speed rotation conditions including critical rotation speeds, so a disk device of a type that writes data such as CD-R and DVD-RW that is sensitive to these adverse conditions can be used at high speed. It becomes possible to become.
[Brief description of the drawings]
FIG. 1 is an explanatory perspective view showing a first example of an embodiment according to the present invention. FIG. 2 is a side view showing a first example of an embodiment according to the present invention. FIG. 4 is a perspective view showing a second example of the embodiment. FIG. 4 is a side view showing the second example of the embodiment according to the invention.
12 Pickup unit 14 Ground cutout 15 Disc 17 Top cutout 18 Turntable A Distance between the lower surface of the disk and the ground surface B Distance between the upper surface of the disk and the top surface

Claims (2)

A turntable that holds and rotates a disk-shaped disk in a housing, a pickup unit that is positioned on the lower side in the rotation axis direction of the disk-shaped disk and reads and writes signals from and to the disk-shaped disk, and the disk-shaped disk A disk drive device having a top surface and a ground surface facing the disk-shaped disk in the vertical direction of the rotation axis of the disk-shaped disk in a state where the disk is held and rotated by the turntable; ,
A rectifying plate constituting the top surface is provided in the housing,
The distance between the top surface and the upper surface of the disk-shaped disk, and the distance between the ground surface and the lower surface of the disk-shaped disk are substantially equal.
A disk tray for carrying the disk-shaped disk to the turntable, wherein the disk tray is provided with a notch for the pickup unit to read and write signals from and to the disk-shaped disk; The side surface is composed of the disc tray ,
Wherein the current plate is pre SL disk drive apparatus, wherein a notch or groove of substantially plane symmetrical provided the shape and the disk surface of the notch or groove provided in the disc tray as a symmetrical plane. Wherein the critical rotational speed is present between the upper and lower limits of the rotational speed in the operating state, the disk drive apparatus according to claim 1.

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