JP2003168282A - Disk drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a disk drive for CD-R and DVD-RW disks which can write data under conditions of a high speed revolution including a critical revolution speed. <P>SOLUTION: A nonmatching air pressure distribution is intentionally created in a drive casing for a deformation mode of the disk which can be assumed for the critical revolution speed so that vibrational amplitude does not grow large by virtue of mutual cancellation of forces which generate deformation. Specifically, a pickup part of the disk and a groove where the pickup is moving are given a prescribed or wider width. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk drive device which suppresses surface vibration, deformation, and inclination which occur when a disk rotates, and more particularly to a CD-ROM and a CD-ROM.
R, CD-RW, DVD, DVD-ROM, DVD-R
The present invention relates to a high-speed rotation disk drive device that uses laser light for reading and writing data such as W.

[0002]

2. Description of the Related Art In recent years, demands for speeding up CD-ROMs, DVD drives, etc. have become strict, and high speed driving up to a critical rotational speed has come to be performed. The critical rotation speed is the rotation speed at which one of the natural frequencies of the backward vibration that travels in the direction opposite to the rotation direction of the disk becomes 0, and when viewed from the housing side, the disk seems to drift slowly. Looks like. The disk is generally unstable at this rotation speed, and is easily affected by external disturbances and greatly deforms and vibrates.
In order to avoid problems, it is desirable to avoid designing at critical speeds.

However, in a CD-ROM drive which pursues high speed, it is generally necessary to change the number of revolutions according to the access position, and it is difficult to use it outside the critical number of revolutions. For this reason, it is necessary to take measures against deformation and vibration associated with rotation near the critical rotation speed. Also,
CD-RO with relatively low recording density
From M, D that requires higher density and higher reading accuracy
With the transition to VD-ROM and the like, the demands for vibration, deformation, and tilt suppression of disks are becoming more severe. In addition, in recent years, the speed of data-writable disk devices such as CD-Rs and DVD-RWs has been increasing. In writing operation, adverse effects such as deformation and vibration become much more serious than in reading operation, and therefore countermeasures are indispensable.

Japanese Unexamined Patent Publication No. 2000-57666 discloses a technique in which the flow of air generated by the rotation of a disk causes vibration. That is, the upper and lower surfaces of the disk are sandwiched by wind loss reduction walls with a width of several mm or less.
Further, by providing a wall also at the end of the disk, the vortex of air generated on the disk surface is minimized, and noise and vibration are reduced. However, with this method, the structure is rather complicated, and since a cutout for the spindle motor and pickup is required on the lower surface side of the disk, turbulent flow and pressure non-uniformity occur at this cutout. , Was causing the vibration.

[0005]

DISCLOSURE OF THE INVENTION CD-ROM, DVD
Stable data reading and writing is realized by devising the internal structure of the drive device and the like. In particular, the present invention provides an effective technique even under conditions of high-speed rotation around a critical rotation speed, where stable reading and writing of signals becomes most difficult.

[0006]

In order to achieve the above object, in the invention of claim 1, at least a turntable for holding and rotating a disk in a housing, and for reading or writing a signal from the disk. In the disk drive device having the pickup section, the radius R of the disk and the width a of the pickup section in the disk circumferential direction are 2R>a> 1.4142R. A featured disk drive device is provided.

According to the second aspect of the present invention, at least a turntable for holding and rotating the disc and a pickup unit for reading and writing signals on the disc are provided in the housing, and the signal is read from the disc.
Alternatively, a disk drive device in which at least one critical rotation speed exists between the upper and lower limits of the rotation speed range for writing a signal to the disk, and the minimum critical rotation speed among the critical rotation speeds is set. When the number of node diameters of the vibration mode of the disc in the number is mi, the radius R of the disc and the width a of the pickup portion in the disc circumferential direction are 2R>a> 2Rsin (π / (2mi)). There is provided a disk drive device characterized by satisfying expression (2).

According to the third aspect of the present invention, at least a turntable for holding and rotating the disk, a pickup section for reading or writing a signal from the disk, and a surface adjacent to the disk and having the pickup section are provided in the housing. Has a notch or groove provided on its surface for moving the pickup portion in the radial direction,
A disk drive device, characterized in that the radius R of the disk and the width L of the notch or groove satisfy 2R>L> 1.4142R (Equation 3). To do.

According to a fourth aspect of the present invention, at least a turntable for holding and rotating the disk, a pickup section for reading or writing a signal from the disk, and a surface adjacent to the disk and having the pickup section are provided in the housing. Has a notch or groove provided on its surface for moving the pickup part in the radial direction, and has a rotational speed range for reading a signal from the disc or writing a signal to the disc. The disk drive device has at least one critical rotation speed between the upper and lower limits, and the node diameter number of the vibration mode of the disk at the minimum critical rotation speed of the critical rotation speed is mi and In this case, 2R>L> 2Rsin (π / (2mi)) (4) is satisfied for the radius R of the disc and the width L of the notch. To provide a disk drive unit.

According to the invention of claim 5, the pickup portion is
The disk drive device according to any one of claims 1 to 4, comprising a pickup body and a pickup cover.

According to a sixth aspect of the present invention, there is provided the disk drive device according to any one of the first to fifth aspects, characterized in that at least the disk-opposing surface of the pickup section is a streamlined curved surface. .

According to a seventh aspect of the present invention, in the disk drive device according to the first, second, fifth or sixth aspect, when the radial width of the pickup portion is b, then a> b There is provided a disk drive device satisfying the above conditions.

The reason why the problems are solved by these means will be described below.

The pressure applied to the disk from the atmosphere is constant and uniform everywhere on the disk when stationary, but a complicated force is applied when rotating. This is because the air flow caused by the rotation of the disk becomes turbulent and interacts with the components inside the housing to create a non-uniform pressure. Deformation and vibration of the disk due to this non-uniform pressure appear particularly strongly at the critical rotation speed, and a large number of write errors occur.
Bring serious adverse effects.

In order to reduce the adverse effect of the uneven pressure wd force, the flow of air on the disk surface may be adjusted so that the pressure distribution on the disk surface is gentle. The above-mentioned JP 2
The method of 000-57666 is an invention based on this technical idea. However, the effect is limited because the wind loss reducing wall has to be provided with a notch on the lower surface side of the disk. In particular, when applied to a high-speed rotation condition near the critical rotation speed where deformation and displacement easily expand, the adverse effect of this defect appears strongly and is not necessarily practical.

On the other hand, the present invention does not aim at a simple uniform pressure distribution. The large deformation that causes a problem at the critical rotation speed can be suppressed without completely uniforming the pressure distribution. The present invention was made by finding the conditions.

In order to understand the conditions to be satisfied by the pressure distribution, it is necessary to understand the cause of the large deformation at the critical rotation speed. The deformation wave traveling in the circumferential direction of the disk must smoothly connect with itself after one round, so there is a limit to the wavelength that can exist stably. This is called a mode,
There is something like Fig. 1. In this figure, + is a portion displaced upward with respect to the paper surface, − is a portion displaced downward, and a straight line passing through the center of the disk is a set of points at which the displacement is zero. The frequency corresponding to each vibration mode is called the natural frequency.

In FIG. 1, for example, (0, 3) mode is displayed, which means that three lines of zero displacement are crossed. The 0 in the (0, 3) mode represents the vibration mode in the radial direction. At a frequency much higher than the drive speed of a normal CD-ROM, a circle with zero displacement appears due to radial vibration. The (1,3) mode or the (2,3) mode appears depending on the number of circles with zero displacement. However, in a normal CD or DVD drive, such ultra-high speed rotation has not yet been put to practical use.

A line having zero displacement is usually called a nodal diameter when it is a diameter line and a nodal circle when it is a circumferential line. In the present specification, description will be made in accordance with the notation. However, since the term “node” is a term for an antinode of a standing wave, it is originally wrong to use it in the description of the present invention.
This is because the vibration excited in the disk at the critical rotation speed is not a standing wave but a traveling wave, as described below. However, the word clause is used because it is common.

The wave of disk deformation that travels on the disk in the circumferential direction is generated even at a critical rotation speed. If an external force is repeatedly applied to the disk at the timing corresponding to the natural frequency, the amplitude of this deformation wave will increase gradually. However, it goes without saying that it is usually impossible for an external force to act on the deformation wave generated on the disk rotating at high speed from the housing in time.

However, at the critical rotation speed, the speed of the deformation wave traveling on the disk in the direction opposite to the rotation direction matches the rotation speed of the disk, so that the deformation wave of the disk is apparently stationary from the housing side. Looks like In this state, it is not necessary to match the timing. If there is a fixed bulge or dent in the housing, the decrease or increase in pressure generated there automatically applies a force with a coincident timing to the disk, and a large deformation is excited. The deformed wave excited in this way is a traveling wave and not a standing wave. If it is a standing wave, it vibrates in the up and down direction of the disc at its belly part, so with a fixed protrusion, etc.
Cannot excite vibration.

Since a large deformation wave that causes a problem at the critical rotation speed is not a standing wave, when a force that displaces upward at a certain portion of the disk is applied, it becomes lower in the region of the opposite phase next to the node. Try to displace. So in the drive,
If there is a structure that applies upward force to the disk, if a similar element that applies upward force is placed next to it, the generation of a large deformation wave at the critical rotational speed
Can be prevented.

General CD-ROM drive device and DV
With the D drive device in mind, the fixed ridges or dents that affect the generation of the deformation wave of the disk are the pick-up part and the groove provided for the pick-up part to move in the radial direction.

Under the above-mentioned technical background, in the invention described in claim 1, the width of the pickup section is limited to have a necessary width for the deformation wave of the (0, 2) mode. There is. As shown in FIG. 1, in the (0, 2) mode, the disc is divided into four equal parts by the nodal diameter, and the width of one region is set as the lower limit a of the width of the pickup portion. In FIG. 5, this a is a chord of arc D. Based on the knowledge of the elementary geometry regarding the length of the string, the lower limit of the pickup part in this case is twice the root of the radius R of the disc (= 1.4142135).
6) is obtained, and Equation 1 is obtained. At other higher vibrations, the width of the individual regions divided by the nodal diameter is smaller than in the (0,2) mode. Therefore (0,
2) For all higher-order natural vibrations of modes and higher, the force is applied to the next opposite phase region across the node,
Deformation and vibration at the critical speed are suppressed.

According to the second aspect of the present invention, the natural vibrations in question are specified, and a force is applied to the adjacent antiphase region across the nodes for the minimum frequency of those natural vibrations. The width of the pickup part is defined. As described above, since the minimum value a of this width is the length of the chord of the arc D in FIG. 5, it can be calculated by elementary geometric knowledge, and
Is obtained. As a result, a force of opposite phase is applied to the natural vibration in a specific range, and deformation and vibration at the critical rotation speed are suppressed.

According to the third aspect of the invention, the width of the groove for moving the pickup portion in the radial direction is limited to a sufficiently large size. This gives (0,
2) Forces of opposite phases are applied to higher-order natural vibrations of modes and higher, and deformation and vibration at the critical rotation speed are suppressed. As shown in FIG. 1, in the (0, 2) mode, the disc is divided into four equal parts by the nodal diameter, and the width L of one of the regions is set as the lower limit of the groove width. In FIG. 5, this L is the chord of the arc D. From a rudimentary geometrical knowledge of the chord length, it is found that the lower limit of the groove in this case is twice the root of the radius R of the disk (= 1.41421356), and Equation 3 is obtained. At other higher vibrations, the width of the individual regions divided by the nodal diameter is smaller than in the (0,2) mode. Therefore, for all higher-order natural vibrations in the (0, 2) mode and higher, a force that cancels the generation of waves is applied to the region of the opposite phase next to the node, and the deformation at the critical speed And vibration is suppressed.

According to the fourth aspect of the invention, the natural vibration in question is specified, and the width of the groove is determined so that a force in antiphase is applied to the natural vibration of the minimum frequency. The minimum value L of this width can be calculated by elementary geometric knowledge, and conditional expression 4 is obtained. As a result, an opposite phase force is applied to the natural vibration in a specific range,
Deformation and vibration at the critical speed are suppressed.

According to the fifth aspect of the present invention, it is specified that the pickup section includes a pickup body and a pickup cover. With this, it is possible to freely select the outer dimensions of the pickup, and it becomes easy to configure a pickup portion having a large size or a pickup portion having a different shape as needed.

According to the sixth aspect of the invention, since the upper surface of the pickup portion has a streamlined shape with little air resistance, the air resistance itself is reduced, and the deformation and vibration of the disk are suppressed.

In the invention according to claim 7, the size of the pickup portion in the radial direction b is set to be less than the size in the circumferential direction a, whereby the generated pressure and loss can be reduced, and the deformation and vibration of the disk can be suppressed. It

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) A first embodiment of the present invention will be described below with reference to FIGS. FIG. 2 schematically shows the positional relationship between the groove and the deformation excited on the disk at the critical rotation speed in the conventional drive. The components of the disk drive, such as the power supply device, which are not directly related to the present invention are not shown. Since the air pressure is relatively increased above the groove, the disc receives an upward force F1. The disk that receives the force induces a deformation wave such that the area A immediately above the groove becomes a mountain, and is displaced upward by d1. On the other hand, in regions B and C adjacent to A, the phases of the deformed waves are opposite to each other, so d2, d
Displaces 3 downwards. The size of d2 and d3 is equal to d1 if there is no disturbance factor. On the other hand, FIG. 3 shows a case where the method of the present invention is used. The air pressure rises above the groove, and the deformation wave is induced so that the area A immediately above the groove becomes a mountain, but in this example, the upward force also extends to the areas B and C. If no upward force is applied, it should try to displace in B and C as in Fig. 2, but because the groove is wide, part of it is erased, resulting in d5, The displacement amounts of d6 and d7 are smaller than those of the conventional example of FIG. 2 even under the same conditions.

(Second Embodiment) Next, a second embodiment will be described with reference to FIG. In FIG. 4, the groove 18 for moving the pickup portion has a width L exceeding 1.4142 times the disk radius R by the method of the present invention. In addition, the length a of the pickup unit 14 in the circumferential direction exceeds 1.4142 times the disc radius R, and the pickup unit is composed of a pickup and a pickup cover. Is made smaller than the circumferential length a.

By not only widening the width L of the groove but also by attaching a pickup cover to the pickup to form a wide pickup portion, the force for eliminating the deformation of the disk explained in FIG. It is given and the deformation is suppressed more effectively. Further, by keeping the radial length b of the pickup portion smaller than the circumferential length, unnecessary air resistance is reduced and vibration is further reduced.

(Third Embodiment) Next, a third embodiment will be described with reference to FIG. The drawing shows claim 5 of the present invention.
The method of (6) and (6) is applied, and the pickup unit 24 includes a pickup 25 and a pickup cover 26. The surface of the pickup cover 26 facing the disc has a substantially streamlined cross section. As a result, in the pickup unit, the air flow is adjusted, and unnecessary noise and vibration are suppressed.

Next, items common to the first and second embodiments will be described. In order to obtain a preferable effect by widening the width, there are conditions for the size of the groove and the pickup section. Figure 5
Explains this limitation. FIG. 5 is a plan view of the disk drive as viewed from directly above (on the clamper side in the case of a CD-ROM), showing a situation where (0,3) mode vibration is induced in the disk. In order for the groove to act to suppress this vibration, the groove must extend beyond the area A and extend to areas B and C in FIG. Therefore, the lower limit of the groove width is the lateral width of the region A, that is, the length of the chord of the arc D, and can be calculated by elementary knowledge of geometry. This condition does not change even if the groove is changed to the pickup cover.

Since there are a plurality of critical rotation speeds depending on the vibration mode, the length of the chord of the arc D also differs depending on the rotation speed of interest. Therefore, the critical rotational speed in question is determined in advance according to the rotational speed range used in the operation of the disk drive, and if there are multiple critical rotational speeds, the largest groove width should be adjusted to the required critical rotational speed. , You have to design the drive. For example, current standard diameter 1
In the case of a disc made of polycarbonate resin having a thickness of 2 cm and a thickness of 1.2 mm, the critical rotation speed corresponding to the natural vibration of the (0,2) mode is about 6000 rpm, and the critical rotation speed of the (0,3) mode is about 7400 rpm, (0,4). 9400r in mode
pm.

In general, the higher the critical rotational speed, the greater the number of corresponding node diameters and the shorter the chord of the arc D. Therefore, the minimum critical rotational speed within the operating rotational speed range is confirmed and the corresponding chord The width of the pickup and groove must be determined so that it exceeds the length.

If the rotation speed range to be used does not include the critical rotation speed, the consideration of the present invention is not always necessary. However, CDs and DVDs are basically removable disks, and if the material is changed due to a change in standards, the critical rotation speed on the disk side will change, even if the drive itself does not change. It may be necessary to operate at a critical speed.

In order to avoid such a situation, in designing the drive, it is desirable to follow the technical idea of the present invention even if it is out of the critical rotational speed for the time being. That is, considering that the critical rotation speed may change if the disc material and design are different, even if the critical rotation speed is out of the rotation speed range used for driving the drive, Measures should be taken according to the method of claim 2 or claim 4 of the invention. Alternatively, if the method of claim 1 or 3 is adopted, an effect can be expected for all critical rotation speeds having frequencies of (0, 2) mode or higher. However, since this method has severe restrictions on the size of the pickup section and the groove section, it is necessary to properly use the method different from the methods of claims 2 and 4 in consideration of the ease of design.

The embodiment of the present invention is not limited to the contents described here. The disc tray is not an essential component, and the width of the pickup portion may be larger than the groove portion. Further, the spindle motor, the clamper, etc., which are omitted in the drawing, are provided unless they affect the essence of the present invention.
Any configuration may be selected.

Furthermore, the technical idea of the present invention is not necessarily exhausted by the methods recited in the claims. In order to suppress the deformation of the disk, it is not impossible to adjust the space shape in the housing so that the force of the opposite phase is applied to the deformation by using more sophisticated mathematical methods. However, from a practical point of view, the effect can be obtained if the size is limited with respect to the most basic elements such as the pickup section and the groove cutout without taking such a trouble. For practical production, such a concise and essential limitation is preferable, and the engineering value is high. The present invention has been made based on such an idea.

[0042]

According to the present invention, the deformation, tilt and vibration occurring in the disk body can be suppressed by a relatively simple design measure such as changing the size of the pickup section and the groove in which the pickup section moves. In particular, it is possible to effectively suppress deformation, inclination, vibration and the like under high-speed rotation conditions including the critical rotation speed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a vibration mode of a disc.

FIG. 2 is an explanatory diagram explaining a deformation of a disk in a conventional disk drive.

FIG. 3 is an explanatory diagram for explaining the deformation of the disc in the disc drive according to the present invention.

FIG. 4 is a perspective view illustrating the structure of a disk drive according to the present invention.

FIG. 5 is an explanatory diagram explaining the basis of the limiting conditions of the present invention.

FIG. 6 is a sectional view of a disk drive according to the present invention.

[Explanation of symbols]

1, 13, 23 Disc 2 Wide Groove or Notch in the Present Invention 3 Wide Pickup Section 4 in Present Invention 4 Prior Art Groove or Notch A Adjacent to regions B and C A that deform upward on the disc, Area F1 on the disk that deforms downwards Upward force F5, F6, F7 applied to the disk near the groove in the prior art In the present invention, an upward force d1 applied to the disk near the groove in the present invention. Amount of displacement d2, d3 of conventional technology, which occurs according to displacement of A, B, C
Downward displacement d5 in the present invention A displacement amounts d6 and d7 in the present invention In the present invention, downward displacement in portions B and C that occur in response to the displacement of A R radius of the disk a circumferential direction of the pickup portion Length b Radial length of pickup part L Width of notch D Length of arc in area delimited by nodal diameter θ Center angle of area delimited by nodal diameter 11,21 Drive housing 14,24 Pickup Part 15, 25 Pickup 16, 26 Pickup cover 17, 27 Guide 18 Wide groove or notch in the present invention 22 Disc tray

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Sadakazu Hirono             248 Nakajuku, Aichigawa-cho, Aichi-gun, Shiga Nidec             Shiga Technology Development Center Co., Ltd.

Claims (7)

[Claims] 1. A disk drive device having at least a turntable for holding and rotating a disk and a pickup section for reading or writing a signal in the disk, wherein a radius R of the disk and a pickup are provided. A disk drive device characterized by satisfying 2R>a> 1.4142R .. 2. A housing has at least a turntable for holding and rotating a disc, and a pickup unit for reading or writing a signal on the disc,
A disk drive device in which at least one critical rotation speed exists between the upper and lower limits of the rotation speed range for reading a signal from the disk or writing a signal to the disk. Of the above, if the node diameter number of the vibration mode of the disc at the minimum critical speed is mi, then for the radius R of the disc and the width a of the pickup in the disc circumferential direction, 2R>a> 2Rsin (π / (2mi )) ... A disk drive device characterized by satisfying Equation 2. 3. A housing having at least a turntable for holding and rotating a disc, a pickup unit for reading or writing signals from the disc, and a surface adjacent to the disc and provided with a pickup unit. A disk drive device having a notch or groove provided on a surface thereof for allowing a pickup unit to move in a radial direction, the radius R of the disk, the width L of the notch or groove,
With respect to 2R>L> 1.4142R ... A disk drive device characterized by satisfying Expression 3. 4. A housing having at least a turntable for holding and rotating a disc, a pickup unit for reading or writing a signal from the disc, and a surface adjacent to the disc and provided with a pickup unit. There is a notch or groove provided on the surface for the pickup unit to move in the radial direction, between the upper and lower limits of the rotational speed range for reading signals from the disk or writing signals to the disk. Is a disk drive device that has at least one critical rotation speed, and if the node diameter number of the vibration mode of the disk at the minimum critical rotation speed of the critical rotation speed is mi, then Regarding the radius R and the width L of the notch, 2R>L> 2Rsin (π / (2mi)) .. Place 5. The pickup unit comprises a pickup body and a pickup cover.
5. The disk drive device according to any one of items 4 to 4. 6. The disk drive device according to claim 1, wherein at least the disk-opposing surface of the pickup section is a streamlined curved surface. 7. The disk drive device according to claim 1, 2, 5 or 6, wherein the pickup portion has a radial width b.
In such a case, a> b ... A disk drive device characterized by satisfying Expression 5.