WO2005091297A1

WO2005091297A1 - Apparatus for reading and/or writing at least one rotatable information carrier disk

Info

Publication number: WO2005091297A1
Application number: PCT/IB2005/050850
Authority: WO
Inventors: Alexander C. Geerlings; Rick Scholte
Original assignee: Koninklijke Philips Electronics NV
Current assignee: Koninklijke Philips NV
Priority date: 2004-03-15
Filing date: 2005-03-08
Publication date: 2005-09-29
Anticipated expiration: 2006-09-15
Also published as: TW200532665A

Abstract

Apparatus for reading and/or writing at least one rotatable information carrier disk, comprising a cavity for receiving said disk, wherein the apparatus is provided with at least one flow conditioner (4) which abuts said cavity, wherein the flow conditioner is arranged to influence fluid flow, resulting from rotation of the disk in said cavity, such, that mechanical vibrations of mechanical parts of the apparatus, which vibrations may result from the rotation of said disk in said cavity, are reduced. The invention further provides a use of said apparatus. The invention also provides a method for manufacturing such an apparatus.

Description

Apparatus for reading and/or writing at least one rotatable information carrier disk

The invention relates to an apparatus for reading and/or writing at least one rotatable information carrier disk, comprising a cavity for receiving said disk. Such an apparatus is known from the art. The apparatus may, for instance, be a CD player, hard disk or the like. The disk may be, for instance, a information carrier for carrying data, video and/or audio information, computer information and/or the like. The information may be stored, for instance, in one or more information layers of such a disk. During use, a disk is rotated in said cavity for reading and/or writing information from and/or to the disk. For obtaining high information transfer rates, the disk is rotated preferably at relatively high speeds, as is achieved for instance by the "52x speed" drives or similar disk drives which are presently marketed by various companies. A problem of the known apparatus is the high noise production thereof, particularly during high speed disk rotation. It is know, to apply noise damping devices, for instance sound absorbers, for reducing the amount of noise produced by the apparatus during use. However, it has been found that such damping devices are not sufficiently able to avoid or reduce noise at the relatively high rotation speeds which are preferably used. Besides, such damping devices usually require a relatively large amount of space, which leads to a rather bulky apparatus. It is an object of the invention to solve at least part of the abovementioned problems. Particularly, the present invention aims to improve the apparatus such, that the apparatus produces relatively little, or at least less, noise during high rotation speeds of said disk. To this aim, the present invention provides an apparatus which is characterized by the features of claim 1. The present apparatus is provided with at least one flow conditioner which abuts said cavity, wherein the flow conditioner is arranged to influence fluid flow, resulting from rotation of the disk in said cavity, such, that mechanical vibrations of mechanical parts of the apparatus, which vibrations may result from the rotation of said disk in said cavity, are reduced. The present invention is based on the inventive notion, that mechanical parts of the apparatus are a main source of undesired noise during high speed rotation of a disk in said cavity, whereas the fluid flow in said cavity can be influenced to reduce such mechanically produced noise. Such mechanical noise is a result of mechanical vibrations of mechanical apparatus parts, for instance mechanical resonances due to the disk rotation. For instance, the flow conditioner may be arranged to influence the fluid flow such, that mechanical resonances of mechanical parts of the apparatus are reduced or avoided. Note, that such mechanical noise is different from aerodynamic noise, since aerodynamic noise results from fluid flow as such. Therefore, the present flow conditioner has to be distinguished from a damper which is specifically designed for absorption of aerodynamic noise. A further advantage of the present invention is, that the apparatus can be made relatively compact and relatively cheap, using relatively inexpensive means for reducing operating noise thereof, whilst a good level of noise reduction can be achieved during use thereof. According to one aspect of the present invention, the flow conditioner is arranged to influence said fluid flow such, that an underpressure at a centre of the disk is reduced during the rotation of the disk. Surprisingly, it has been found that mechanical noise of the apparatus can be substantially reduced by the application of such flow conditioner. Advantageously, the apparatus comprises a clamper for retaining said disk at the disk centre, wherein the clamper is mechanically coupled to a mechanical structure of the apparatus. Said mechanical structure may comprise, for instance, a mechanical support structure. Such a structure usually is coupled to a housing of the apparatus using vibration damping means. Besides, usually, such a structure is provided with a movable pickup unit, for instance an optical or magnetical pickup unit, which is arranged for the reading and/or writing of said disk during use. Besides, a motor may be provided for rotating a disk being held by said clamper. The mechanical structure is usually provided with such motor. Such a motor/clamper arrangement may couple said mechanical structure and the disk. According to a further aspect of the present invention, said clamper is a ball clamper. Such a clamper is relatively compact and inexpensive, for instance compared to a known clamper bridge which is applied in internal front loading computer CD/DVD drives. Besides, it has been found that the present flow conditioner is surprisingly suitable for reducing mechanical noise of an apparatus which is provided with such a ball clamper. Furthermore, said flow conditioner is preferably arranged to influence said fluid flow such, that mechanical vibrations of said mechanical structure are reduced or avoided. For instance, the flow is conditioned such by the flow conditioner, that said mechanical structure is less excited via the clamper. The flow conditioner may, for instance, influence said fluid flow such, that vibrations of the mechanical structure at one or more eigenfrequencies of the structure are reduced or avoided. It has been found, that surprisingly good results are obtained when the flow conditioner reduces the underpressure at the centre of the disk during the rotation of the disk. A possible explanation may be, that a reduction of the underpressure at the centre of the disk leads to an improvement of the clamper force, so that vibrations or one or more resonances of the mechanical structure, which is usually, mechanically coupled to the clamper, are being reduced. The present invention is particularly advantageous for the case that the apparatus is arranged for external and/or portable use, comprising for instance said ball clamper. Besides, the apparatus may further be provided, for instance, with a removable cover which abuts a first side of the cavity, opposite the clamper, during use. Such a cover may simply be provided by said flow conditioner. An other aspect of the present invention is provided by the features of claim

20. Since the apparatus according to the invention is used for reading and/or writing at least one information carrier disk, the reading and/or writing of the disk can be achieved with relatively little, or at least less, mechanically induced noise. Further advantageous embodiments of the invention are described in the dependent claims.

The invention will now be described in more detail on the basis of exemplary embodiments shown in the accompanying drawing. fig. 1 is a schematic-cross section of an embodiment of the invention; fig. 2 is a cross-section over line II-II of fig. 1; fig. 3 is a cross-section over line III-III of fig. 2; and fig. 4 show results of an example of the invention. Figures 1-3 show an embodiment of an apparatus 1 for reading and/or writing at least one rotatable information carrier disk 2. The apparatus may be arranged, for instance, for optically reading and/or writing at least one optical information carrier disk 2. The apparatus is provided with a housing 9, and a circular cavity 3 for receiving said disk 2. A ball clamper 10 is provided, having radially protruding clamping balls 14, for retaining the disk 2 by the disk centre in the cavity 3. The clamper also serves as a turntable for rotating the disk during use. The clamper 10 is mechanically coupled to a motor 15 for rotating the clamper 10 around a rotation axis A. Besides, the clamper is mechanically coupled to a mechanical structure 11 of the apparatus 1. This mechanical structure 11 is provided with a frame extending in the housing 9 of the apparatus 1. The frame of the mechanical structure 11 is coupled to the housing by vibration dampers 8, for instance spring means, elastic material and/or the like. A pick up unit 12 is movably connected to the mechanical structure 11. An arrow B schematically depicts the direction of movement of the unit 12. The pick up unit 12 is arranged for optically writing and/or reading information to and/or from the disk 1. To this aim, the pick up unit 12 comprises a lens L. The mechanical structure 11 and pick up unit 12 as such are known from the art, and have therefore been drawn schematically. As is clearly shown, during use, the mechanical structure 11 and the disk 2 are mechanically connected to one another via the motor 15 and the clamper 10. One longitudinal side of said cavity 3 is provided with a cover 5 for sealing the respective side of the cavity 3. The cover 5 is removable from said cavity 3 for gaining access to the cavity 3, for placing and removing the disk 2. During the insertion or removal of a disk 2, the disk 2 is at least moved in an axial direction, parallel to said rotation axis A, contrary to a known, front loading disk drive comprising for instance a clamper bridge. Particularly, the cover 5 is pivotally connected to a side wall of the apparatus 1, via a hinge H. The cover 5 is, for instance, provided with a transparent cover part 16, depicted in fig. 2, so that part of the disk 2 can be viewed from outside the apparatus 1 during operation. An inner side of the cover 5, facing the cavity 3 and said clamper 10, is provided with a flow conditioner 4. The flow conditioner 4 abuts the cavity 3 when the cover 5 is in the closed position, shown in fig. 1. The flow conditioner 4 is arranged to influence fluid flow, resulting from rotation of the disk 2 in said cavity 3, such, that mechanical vibrations of at least the mechanical structure 11 of the apparatus 1 are reduced or avoided. Said vibrations may result from the rotation of said disk 2 in said cavity 3, particularly at high disk speeds. The present flow conditioner 4 is arranged to influence said fluid flow such, that an underpressure at a centre C of the disk 2 is reduced during the rotation of the disk 2. Besides, the flow conditioner 4 is preferably arranged such, that the flow conditioner 4 substantially does not penetrate a turbulent boundary flow layer, which boundary flow abuts said disk 2 during high speed rotation of the disk 2. Therefore, an undesired high rise of the drag on the disk 2 can be avoided, so that a respective rise of the power consumption of the motor 15 can be avoided. The flow conditioner 4 may be arranged in various ways. The present flow conditioner 4 comprises a flow conditioning profiling. The profiling comprises a number, or pattern, of ribs 6. These ribs 6 extend in substantially radial directions with respect to the virtual rotation axis A, which rotation axis A extends in the centre of said disk 2 during use. As is shown in fig. 3, each rib 6 has a square or rectangular cross-section. Preferably, the thickness of each rib 6 of said profiling, depicted by arrow T in fig. 3, is in the range of about 0,5-2 mm, measured in an axial direction Z with respect to said cavity 3. Good results have been obtained when said thickness T is about 1 mm. Furthermore, the width W of each rib 6 of said profiling may be in the range of about 0,1-2 cm, measured in a tangential direction Y, which direction is parallel to the direction of disk rotation during use. Good results have been found when said width W is about 1 cm. In the present patent application, terms as "substantially", "about" or similar terms relating to certain values should at least be construed as meaning a value which is in the range of plus and minus 10% from the mentioned value. Furthermore, the ribs 6 may have other dimensions than the mentioned ranges and values. The dimensions of the ribs 6 may depend, for instance, on the thickness of a turbulent boundary flow layer which abuts said disk 2 during rotation of the disk. During use, the disk 2 is rotated in the cavity 3 around the rotation axis A by the motor/clamper arrangement 10, 15. The rotation of the disk 2 leads to an air flow within the cavity 3. The ribs 6 influence the flow such, that the underpressure near the clamper 10 is reduced. Such underpressure can be relatively large when no flow conditioner 4 is provided, particularly when the disk 3 is rotated at high speeds in the cavity 3. Surprisingly, the ribs 6 of the flow conditioner 4 lead to a substantial reduction of mechanical noise. Such noise would be generated by mechanical parts of the apparatus 1, for instance by the mechanical structure 11, for the case that no flow conditioner 4 were provided. It is thought, that the clamper 10 can retain the disk 1 relatively firmly because of the reduction of underpressure near the clamper 10. Because of the reduction of the underpressure, a possible vibrational excitation and mechanical resonance of the mechanical structure 11 is found to be avoided or reduced substantially, leading to a reduction of overall noise produced by the apparatus 1.

Example Six devices, each substantially the same as the device shown in figures 1-3, were first tested for noise production, without the application of a profiling. Then, the flow conditioner 4 was applied to the cover 5 of the devices and the noise production test was repeated. The conditioner 4 used, consisted of the pattern of ribs 6 as shown in figures 2 and 3. The width W of each rib 6 was about 1 cm. The thickness T of each rib 6 was about 1 mm. The devices used were 52x speed CD ROM drives. Figure 4 show the results of the tests. Therein, a dashed line 100 shows the average measured sound power in dB as a function of the frequency in Hz, for the case that the CD ROM drives were not provided with the flow conditioning profiling 4. A continuous line 101 shows the sound power as a function of the frequency, when the profiling 4 was in place. Clearly visible in the dashed line 100 is a relatively high resonance peak, located between the 500 and 1000 Hz. It is believed, that this resonance peak is generated by mechanical parts, particularly by the mechanical structures 11, of the CD ROM drives. In the continuous line 101, the resonance peak has been reduced with over 10 dB. This significant reduction of noise is attributed to the flow conditioning within the disk cavity 3, which is achieved by said flow conditioning profiling 4. Also, a lower frequency resonance peak, near 200 Hz, has clearly been reduced to some extent. Above 1 kHz, the spectrum has not changed significantly, when comparing the different test results 100, 101. This upper part of the spectrum is mainly attributed to aerodynamic noise, resulting from air flow as such within the disk cavity 3. From this example it follows, that the application of said flow conditioner 4 leads to significant reduction of noise levels of the apparatus 1. Although the illustrative embodiments of the present invention have been described in greater detail with reference to the accompanying drawing, it is to be understood that the invention is not limited to those embodiments. Various changes or modifications may be effected by one skilled in the art without departing from the scope or the spirit of the invention as defined in the claims. For instance, the apparatus may be arranged for optically reading and/or writing information. Alternatively, the apparatus may be arranged, for example, for electromagnetically reading and/or writing information, for instance when the apparatus is a hard disk or a similar device. Besides, the apparatus may comprise on or more cavities 3 for receiving one or more disks 2. Furthermore, the apparatus 1 may be provided with one or more flow conditioners 4, each flow conditioner 4 abuting one or more longitudinal sides of a disk cavity 3. Furthermore, said profiling may be arranged in various ways and comprise various materials. For instance, the profiling may comprise one or more ribs, strips or the like, which are fixed to an inner side of the device, facing the disk cavity 3. Besides, the apparatus can be manufactured in various ways. For the case that an apparatus is provided, which already comprises a cavity 3 for receiving said disk 2, an apparatus according to an embodiment of the present invention can simply be manufactured, when an inner side of the apparatus, facing the cavity 3 during use, is being provided with a flow conditioner 4 which is arranged for influencing fluid flow, resulting from rotation of a disk 2 in said cavity, such, that mechanical vibrations of mechanical parts 11 of the apparatus 1, which vibrations may result from the rotation of said disk 2 in said cavity 3, are reduced. In this way, an existing apparatus for reading and/or writing at least one rotatable information carrier disk, can easily be modified for reaching a substantial amount of noise reduction. For instance, a profiling, ribs and/or strips can be fixed to suitable locations on the inside of a cover 5 of such an apparatus. Such profiling, ribs and/or strips may, for example, contain a self-adhesive surface to provide the fixing thereof. On the other hand, separate fixing means, adhesive material and/or the like may be used to apply the flow conditioner to the cover 5 of the apparatus 1.

Claims

CLAIMS:

1. Apparatus for reading and/or writing at least one rotatable information carrier disk, comprising a cavity (3) for receiving said disk (2), wherein the apparatus (1) is provided with at least one flow conditioner (4) which abuts said cavity (3), wherein the flow conditioner (4) is arranged to influence fluid flow, resulting from rotation of the disk (2) in said cavity, such, that mechanical vibrations of mechanical parts (11) of the apparatus (1), which vibrations may result from the rotation of said disk (2) in said cavity (3), are reduced.

2. Apparatus according to claim 1, wherein the flow conditioner (4) is arranged to influence said fluid flow such, that an underpressure at a centre (C) of the disk (2) is reduced during the rotation of the disk (2).

3. Apparatus according to any of the preceding claims, wherein the apparatus (1) comprises a clamper (10) for retaining said disk (1) at the disk centre, wherein the clamper (10) is mechanically coupled to a mechanical structure (11) of the apparatus (1).

4. Apparatus according to claim 3, wherein said flow conditioner (4) is arranged to influence said fluid flow such, that mechanical vibrations of said mechanical structure (11) are reduced or avoided.

5. Apparatus according to claim 3 or 4, wherein said clamper is a ball clamper.

6. Apparatus according to any of the claims 3-5, wherein said mechanical structure (11) is coupled to a housing (9) of the apparatus (1) by at least one or more vibration dampers (8).

7. Apparatus according to any of claims 3-6, wherein said clamper (10) is at least coupled to the mechanical structure (11) by a motor (15).

8. Apparatus according to any of claims 3-7, wherein the mechanical structure

(11) is provided with a movable pick-up unit (12) for reading and/or writing information from and/or to a disk (2) during use.

9. Apparatus according to any of the preceding claims, wherein at least one side of said cavity (3) is provided with a cover (5), wherein an inner side of the cover, facing the cavity (3), is provided with said flow conditioner (4).

10. Apparatus according to claim 9, wherein said cover (5) is removable from said cavity (3) for gaining access to the cavity (3).

11. Apparatus according to any of the preceding claims, wherein said flow conditioner (4) comprises at least one flow conditioning profiling.

12. Apparatus according to any of the preceding claims, wherein said flow conditioner (4) comprises a number of ribs (6).

13. Apparatus according to claim 12, wherein said ribs (6) extend in substantially radial directions with respect to a virtual rotation axis (A), which rotation axis (A) extends in the centre of said disk (2) during use.

14 Apparatus according to claim 12 or 13, wherein each rib (6) has a square or rectangular cross-section.

15. Apparatus according to any of claims 12-14, wherein the thickness (T) of each rib (6) is in the range of about 0,5-2 mm, measured in an axial direction (Z) with respect to a virtual rotation axis (A), which rotation axis (A) extends in the centre of said disk (2) during use, wherein said thickness (T) particularly is about 1 mm.

16. Apparatus according to any of claims 12-15, wherein the width (W) of each rib (6) is in the range of about 0,1-2 cm, measured in the tangential direction (Y) of disk rotation during use, wherein said width particularly is about 1 cm.

17. Apparatus according to any of the preceding claims, wherein the apparatus is arranged for external and/or portable use.

18. Apparatus according to any of the preceding claims, wherein the flow conditioner is arranged such, that the flow conditioner substantially does not penetrate a turbulent boundary flow layer which abuts said disk (2) during rotation of the disk.

19. Apparatus according to any of the preceding claims, arranged for optically reading and/or writing at least one optical information carrier disk.

20. Use of an apparatus according to any of the preceding claims for reading and/or writing at least one information carrier disk (2).

21. Method for manufacturing an apparatus according to at any of claims 1-19, wherein the apparatus is provided with a cavity (3) for receiving said disk (2), wherein an inner side of the apparatus, facing the cavity (3) during use, is being provided with a flow conditioner (4) which is arranged for influence fluid flow, resulting from rotation of a disk (2) in said cavity, such, that mechanical vibrations of mechanical parts (11) of the apparatus (1), which vibrations may result from the rotation of said disk (2) in said cavity (3), are reduced.

22. Method according to claim 21, wherein the inside of a removable cover (5), abuting said cavity (3) during use, is being provided with said flow conditioner (4).