Abstract:
A hard disk drive contains a disk assembly and a cylindrical disk container. The drive also includes a base around which a peripheral wall extends, a catching chamber including a partition wall partitioning the base into the catching chamber and a disk container, and a top cover functioning as a lid of the base. In addition, the hard disk drive has a first gasket as a first gasket section existing between the top cover and a peripheral wall of the base, and a second gasket as a second gasket section existing between the top cover and the partition wall of the catching chamber.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a disk drive apparatus that is represented by a hard disk drive, and in particular, to technology for improving a collection efficiency of a dust filter in a disk drive apparatus. 
     2. Background Art 
     A hard disk drive that is the most general as data storage means of a computer (hereinafter, an HDD) has the structure of locating one or a plurality of magnetic disk platters in the same shaft and driving the one or plurality of magnetic disk platters by a spindle motor. Reading and writing is performed by a magnetic head which is provided with facing respective surfaces of the magnetic disk, and this magnetic head is driven by an actuator, that is, a voice coil motor (hereinafter, a VCM) in general. The above-described magnetic disk, magnetic head, and actuator are contained in a housing that is called a disk enclosure. The disk enclosure consists of a base made of a shallow-box-like aluminum alloy and a top cover sealing an opening section of the base. 
     Main technical subjects in HDDs are to improve memory capacity per magnetic disk platter, and to improve reading speed of data, stored in a magnetic disk, and writing speed of data into the magnetic disk. As for the latter, it is possible to improve reading and writing speed of data by shortening seek time when the magnetic head moves to a necessary track on the magnetic disk. Since the magnetic head is driven by a VCM as described above, it is possible to accelerate the seek time by enhancing the performance of this VCM. In order to enhance the performance of the VCM, it is sufficient just to adopt another permanent magnet that configures the VCM and has a stronger magnetic characteristic, or to enlarge a magnetic field applied to the voice coil by making the permanent magnet thicker. Nevertheless, the enhancement of the magnetic characteristic of a permanent magnet is also near to its limit. Furthermore, in an HDD that is requested to be small, there is a limit to make a permanent magnet thicker than a current one. 
     In addition, by accelerating the rotational speed of a magnetic disk, it is possible to improve the reading and writing speed of data. Nevertheless, if the rotational speed of a magnetic disk is accelerated, a probability that dust collides with a magnetic head becomes higher even if the same number of dust exists in an HDD. This collision may cause a damage of the magnetic head, and magnetic disk. On the other hand, because the floating height of a magnetic head from a magnetic disk is also lowered so as to correspond to capacity expansion of the magnetic disk, there is a possibility of collision even if the dust has small size that has not been a big issue up to now. Therefore, dust reduction in an HDD becomes an important subject. 
     Because a disk enclosure configuring an HDD consists of a base and a top cover, and an opening section of the base is sealed by the top cover, dust hardly enters into the HDD after the assembly of the HDD. Therefore, dust becoming a problem is mixed inside the disk enclosure in the process of assembling the HDD. The HDD has a catching mechanism to catch this dust. 
     FIGS. 9 and 10 are perspective views showing the configuration of a disk enclosure  116  configuring a conventional HDD. FIG. 9 shows a condition that a base  112  and a top cover  114  are separated from each other, and FIG. 10 shows a condition that the top cover  114  is mounted on the base  112 . In addition, the top cover  114  shown in FIG. 9 is a backside facing the base  112 . Furthermore, in FIG. 10, in order that the inside of the base  112  can be observed, the top cover  114  is shown in a transparent condition. 
     The base  112  has a peripheral wall  112   a  that is stood around its outer periphery. In an area surrounded by the peripheral wall  112   a , there are a disk container  112   b  containing a disk assembly that consists of a magnetic disk and a spindle motor rotationally driving the magnetic disk, and an actuator container  112   c  accommodating an actuator mechanism for making a magnetic head seek a track on the magnetic disk. The catching mechanism  113  of dust is located in the outer periphery of the disk container  112   b.    
     An enlarged top view showing the vicinity of the catching mechanism  113  is shown in FIG.  4 . The catching mechanism  113  has a partition wall  113   a , stood at a predetermined distance from the peripheral wall  112   a  of the base  112 , and a filter  113   b , located between the peripheral wall  112   a  and partition wall  113   a . A catching chamber  113   e  is formed between the partition wall  113   a  and peripheral wall  112   a , and an inlet  113   c  is formed in one end of the catching chamber  113   e  and an outlet  113   d  is in another end. 
     Since the magnetic disk turns counterclockwise (shown by a dotted arrow in the figure), a counterclockwise air stream occurs in the disk container  112   b . Dust in the HDD floats with this air stream. As for this air stream, because linear velocity caused by the rotation of the magnetic disk becomes larger as going to the outer periphery, dust moves along the peripheral wall  112   a . In addition, the dust enters the catching mechanism  113  from the inlet  113   c  with the air stream, and is caught by the filter  113   b . The air stream after the dust being caught is exhausted from the outlet  113   d . Although the dust in the HDD is caught in this manner, it is requested to improve a collection efficiency of the filter  113   b  in connection with accelerating the rotation speed of the magnetic disk. Then, the present invention is intended to improve a dust collection efficiency in a disk drive apparatus represented by an HDD. 
     SUMMARY OF THE INVENTION 
     As an index for measuring the collection efficiency in the filter  113   b , there is the pressure drop before and after the filter  113   b . This is an evaluation method adopted also in IDEMA (International Disk Drive Equipment Material Association). Thus, in FIG. 4, let pressure before the filter  113   b  be Pf and let pressure after the filter  113   b  be Pr. The larger the pressure drop obtained from Pf-Pr is, the more volume of air passes the filter  113   b . Assuming that dust is included uniformly in the air passing the catching mechanism  113 , that more volume of air passes the filter  113   b  means that more volume of dust collides against and is caught by the filter  113   b . Therefore, the present inventor investigated to enlarge the pressure drop (L) obtained from Pf-Pr. 
     It is possible to enlarge the pressure drop (L) by increasing Pf or decreasing Pr. Then, first, a review about structure of the catching mechanism  113  was performed about whether Pr could be increased. In order to increase Pr, it is effective to enhance airtightness in the catching chamber  113   e  that is a space formed by the partition wall  113   a , filter  113   b , peripheral wall  112   a , and top cover  114 . Nevertheless, it is confirmed that airtightness of the catching chamber  113   e  is not enough in the catching mechanism  113  of the conventional HDD. 
     As shown in FIGS. 9 and 10, a gasket  115  is provided in a back face of the top cover  114 , and when the top cover  114  is mounted on the base  112 , the gasket  115  is pressed on a top face of the peripheral wall  112   a  in the base  112  to secure airtightness against the outside. Here, a partial cross section of the catching mechanism  113  is shown in FIG. 5A, and according to the figure, a gap is formed between the partition wall  113   a  and top cover  114 . This is because there was concern about not being able to secure the airtightness in the HDD because of the lack of contact pressure of the gasket  115  and peripheral wall  112   a  if the partition wall  113   a  contacts to the top cover  114 . In general, although the base  112  consists of aluminum alloy formed by die casting, it is difficult to form highly precise parts by die casting. Owing to that, conventionally, the base  112  has been designed so that the contact of the partition wall  113   a  and top cover  114  is surely avoided. Therefore, for example, in such an aspect that is shown by a solid arrow in FIG. 4, an air stream leaks out from the catching chamber  113   e . As described above, a gap between the partition wall  113   a  and top cover  114  becomes a large factor which obstructs the enhancement of airtightness in the catching chamber  113   e . Nevertheless, that a gap between the partition wall  113   a  and top cover  114  existed was not a technical issue in HDDs before the rotational speed of a magnetic disk was highly accelerated. 
     Then, the present inventor planed to form such a wall that completely isolates the disk container  112   b  from the catching chamber  113   e  except the inlet  113   c  and outlet  113   d . Therefore, the present invention is a disk drive apparatus characterized in comprising: a disk-like medium that is rotationally driven with a rotation axis as a center and stores data; a medium container accommodating the disk-like medium; a wall isolating a catching chamber from the medium container; an inlet introducing an air stream occurring by rotation driving of the disk-like medium; an outlet exhausting the air stream; and a catching chamber catching dust included in the air stream. The wall of the present invention can be implemented by providing a gasket, which is mounted with press on the partition wall  113   a , on the top cover  114 . Thus, it is possible to configure the wall by the partition wall  113   a  and gasket newly provided. Nevertheless, this is an example for easier comprehension of the wall, and hence, this does not become a ground of limiting the present invention. 
     In a disk drive apparatus of the present invention, by providing the wall, it becomes possible to prevent air streams from leaking from the catching chamber to the medium container. Therefore, the front pressure Pf of the filter  113   b  becomes large, and hence it is possible to increase the pressure loss (L). 
     In addition, in a disk drive apparatus of the present invention, the catching chamber can be located in an outer periphery of the medium container. This is because, in a disk drive apparatus, for example, an HDD, an air stream occurs by the rotation of a magnetic disk, and since the linear velocity of the air stream becomes larger as going to an outer peripheral area of a magnetic disk container, it is desirable in view of a collection efficiency to provide the catching chamber in the area. Moreover, in a disk drive apparatus of the present invention, a filter catching the dust can be provided between the inlet and outlet in the catching chamber. 
     A disk drive apparatus of the present invention can be applied to an HDD. Therefore, the present invention provides a hard disk drive characterized in comprising: a disk assembly that consists of a disk-like medium, magnetically storing data, and a spindle motor, rotationally driving the disk-like medium; an actuator that has a magnetic head to store data in and reproduce data from the disk-like medium, and that makes the magnetic head seek the disk-like medium and rotates the magnetic head with a pivot as a center; a base that accommodates the disk assembly and provides an approximately cylindrical disk container, and around which a peripheral wall is provided, a catching chamber which has an inlet and an outlet, communicating with the disk container, and a partition wall partitioning the disk container from the inlet and outlet; a top cover functioning as a lid of the base; a first gasket existing between the top cover and peripheral wall of the base; and a second gasket existing between the top cover and partition wall of the catching chamber. 
     Because the hard disk drive of the present invention has the second gasket between the partition wall and top cover of the catching chamber, insulation between the disk container and catching chamber is realized by the partition wall and gasket. Owing to this, it is possible to prevent an air stream from leaking from the catching chamber to the disk container. 
     In the present invention, although a wall can be formed by making a partition wall high to a top cover, as described above, it is not easy to strictly control the height of the partition wall. Therefore, it is desirable in the present invention to form a gasket, consisting of an elastic body, as a part of a component of the wall. 
     In a hard disk drive of the present invention, it is possible to form the first gasket and second gasket in one piece. Hence it is possible to reduce a manufacturing cost of the gaskets, and to perform mounting operation to the top cover only once. The gasket of the present invention can be made of, for example, rubber such as fluororubber. In that case, it is possible to form the gasket with unifying the first gasket and second gasket by forming a cavity obtained by combining the first gasket and second gasket. 
     In a hard disk drive of the present invention, it is desirable that the height of the partition wall is lower than the height of the peripheral wall. Although this will be described in detail in “Preferred embodiment”, it is because it is effective to keep airtightness by the first gasket if it is assumed that the first gasket and second gasket are equal in thickness. 
     The present invention provides the above-described gasket used in a disk drive apparatus, or a hard disk drive. A gasket that is mounted in a disk drive apparatus whose inside is partitioned into a plurality of partitions, and the gasket is characterized in comprising: a first gasket section forming a loop for keeping airtightness of the disk drive apparatus against the outside; and a second gasket section that configures walls between the plurality of partitions inside the disk drive apparatus and is unified with the first gasket section. 
     In a gasket of the present invention, it is possible that the disk drive apparatus comprises a medium container accommodating a disk-like medium, and a catching chamber catching dust in the disk drive apparatus, and that the second gasket section keeps airtightness between the medium container and catching chamber. Furthermore, in a gasket of the present invention, it is desirable that the height of the second gasket section is lower than the height of the first gasket section. 
     The present invention provides a top cover that configures a disk enclosure of a hard disk drive with a box-like base, the top cover comprising: a flat cover body; a looped first gasket that is fixed around the cover body and is to keep airtightness of the disk enclosure from the outside; and a second gasket that is fixed to the cover body in a loop of the first gasket, and configures a wall in the disk enclosure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     So that the manner in which the features, advantages and objects of the invention, as well as others which will become apparent, are attained and can be understood in more detail, more particular description of the invention briefly summarized above maybe had by reference to the embodiment thereof which is illustrated in the appended drawings, which drawings form a part of this specification. It is to be noted, however, that the drawings illustrate only a preferred embodiment of the invention and is therefore not to be considered limiting of its scope as the invention may admit to other equally effective embodiments. 
     FIG. 1 is an exploded perspective view of one embodiment of a disk enclosure for a HDD constructed in accordance with the present invention. 
     FIG. 2 is a perspective view of the HDD of FIG.  1 . 
     FIG. 3 is a perspective view showing an interior of the HDD. 
     FIG. 4 is an enlarged top view of a catching mechanism of the HDD. 
     FIGS. 5A to  5 C are partial sectional views showing the catching mechanism of the HDD. 
     FIGS. 6A and 6B are tables comparing the pressure measurement readings of the HDD of the present invention and a conventional HDD. 
     FIG. 7 is a perspective view of a modified example of a gasket. 
     FIGS. 8A and 8B are partial sectional views of another modified example of the gasket. 
     FIG. 9 is an exploded perspective view of a disk enclosure for a conventional HDD. 
     FIG. 10 is a perspective view of the conventional HDD. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Hereinafter, an example of applying a disk drive apparatus according to the present invention to a hard disk drive (HDD)  10  will be described with referring to drawings. In the HDD  10 , as shown in FIGS. 1 to  3 , a disk enclosure  16  is configured by encapsulating a shallow-box type base  12 , which is made of aluminum alloy, with a top cover  14 . A gasket  15  is bonded on a back face of the top cover  14 . The gasket  15  can be made of, for example, fluororubber. Since the top cover  14  is screwed on the base  12  through the gasket  15 , the inside of the disk enclosure  16  is hermetically sealed. In this disk enclosure  16 , as shown in FIG. 2, a spindle motor  18  having hub-in construction is provided in the approximate center of the base  12 . On an upper face of a hub (not shown) of this spindle motor  18 , a magnetic disk  22  consisting of glass or aluminum substrates is fixedly mounted with a top clamp  26  through a spacer (not shown) with being coaxially stacked. 
     In addition, in the disk enclosure  16 , an actuator  28  is provided. This actuator  28  has a magnetic head  30 , which performs reading and writing of data, in one end section, its middle section is supported on the base  12  through a pivot  32 , and the actuator  28  is made to be rotatable around the pivot  32 . In another end section of the actuator  28 , a VCM (voice coil motor) coil is provided, and the actuator  28  is rotated by a VCM  36 , provided inside the disk enclosure  16  so as to collaborate with this VCM coil. 
     On an outer face (bottom face) of the base  12 , a card, not shown, is mounted as a circuit board, and this card is made to be a rectangle having such dimensions that this card covers a half of the outer face of the base  12 . Between the card and spindle motor  18 , power, signals, and the like for motor driving are inputted and outputted, and between the card and actuator  28 , power and signals for driving of the VCM coil, reading of the magnetic heads  30 , and the like are inputted and outputted. These inputs and outputs between this card and actuator  28  are performed through the flexible cable (FPC). 
     The HDD  10  according to this embodiment is a disk drive apparatus called ahead load/unload type HDD. This head load/unload type HDD unloads the magnetic heads  30  to a parking position without contacting the magnetic head  30  with surfaces of the magnetic disk  22  by making a ramp block  40  hold the actuator  28  in an idle state. In operation, by being driven by the actuator  28 , the magnetic head  30  is sought above the magnetic disk  22 . 
     The base  12  has a peripheral wall  12   a  that is stood around its outer periphery. The base  12  is partitioned as follows into a plurality of areas. Thus, a disk container  12   b  as a medium container, containing a disk assembly that consists of the magnetic disk  22  and spindle motor  18  rotationally driving the magnetic disk  22 , and an actuator container  12   c  accommodating an actuator mechanism for making the magnetic head  30  perform seek above the magnetic disk  22  are provided in an area surrounded by the peripheral wall  12   a . A dust catching mechanism  13  is located in the disk container  12   b.    
     An enlarged top view showing the vicinity of the catching mechanism  13  is shown in FIG.  4 . The catching mechanism  13  has a partition wall  13   a , stood at a predetermined distance from the peripheral wall  12   a  of the base  12 , and a filter  13   b , located between the peripheral wall  112   a  and partition wall  13   a . A catching chamber  13   e  is formed between the partition wall  13   a  and peripheral wall  12   a , and furthermore, an inlet  13   c  is located in one end and the outlet  13   d  is in another end. 
     A gasket  15  is bonded on a back face of the top cover  14 . The gasket  15  is provided so as to keep airtightness of the HDD  10  against the outside, but the gasket  15  according to this embodiment also provides a gasket  15   b  in a direction of facing the partition wall  13   a  of the base  12 . Thus, it is a characteristic of this embodiment that the gasket  15   b  is provided as a second gasket section besides the looped gasket  15   a  as a first existing gasket section conventionally existing, around the catching mechanism  13 . 
     A cross section of the vicinity of the catching mechanism  13  is shown in FIG.  5 B. Through the gasket  15   a , the peripheral wall  12   a  and top cover  14  of the base  12  contact with each other, and through the gasket  15   b , the partition wall  13   a  and top cover  14  of the catching mechanism  13  contact with each other. Furthermore, as shown in FIGS. 2 and 3, the gaskets  15   a  and  15   b  that form a closed loop surround the catching chamber  13   e  of the catching mechanism  13 . Therefore, airtightness between the catching chamber  13   e  of the catching mechanism  13  and the disk container  12   b  is enhanced more than that of a conventional HDD. 
     Using the HDD  10  according to this embodiment, the pressures before and after the above-mentioned filter  13   b , Pf and Pr, were measured to measure a pressure drop (L), and a pressure ratio (R). In addition, the pressure ratio (R) is a value obtained from Pr/L. In addition, using a conventional HDD similar to the HDD  10  according to this embodiment except not providing the gasket  15   b , the pressures before and after the filter  13   b , P′f and P′r, were measured to measure a pressure drop (L′), and a pressure ratio (R′). Their results are shown in FIG. 6A for this embodiment and in FIG. 6B for the conventional example. From FIG. 6, in the HDD  10  according to this embodiment, Pf is 10.4 mm H20, and hence it can be seen that the pressure before filter  13   b  becomes higher than that of the conventional HDD that has not the gasket  15   b . In addition, finding an improvement effect E about pressure losses (L, L′) from E=L′/L, it is E=1.05, and hence the improvement of 5% is obtained. Moreover, with paying attention to the pressure ratios (R, R′), that of the HDD  10  according to this embodiment is 8.0 for 24.0% of the conventional HDD, and hence it can be seen that a bigger pressure ratio is obtained at the rear of the filter  13   b.    
     Furthermore, according to specifications of IDEMA, cleanup time was measured. In consequence, although the cleanup time of the conventional HDD was 13 seconds, the HDD  10  according to this embodiment was 12 seconds, and hence it was confirmed that the enhancement of the dust collection efficiency was achieved. 
     It can be seen that, by forming a wall isolating the catching chamber  13   e  and disk container  12   b  from each other like the HDD  10  according to this embodiment, as described above, through closely contacting the partition wall  13   a  of the catching mechanism  13  and the top cover  14  through the gasket  15   b , the dust collection efficiency in HDD  10  can be improved. 
     By the way, as shown in FIG. 5B, in the HDD  10  according to this embodiment, the height of the partition wall  13   a  of the catching mechanism  13  is made to be lower than that of the peripheral wall  12   a  of the base  12 . This is to keep the airtightness against the outside by the gasket  15  provided on the top cover  14 . Thus, by screwing the top cover  14  to the base  12 , the gasket  15   a  provided in the top cover  14  is pressed to a top face of the peripheral wall  12   a  of the base  12 , and the gasket  15   b  is pressed to a top face of the partition wall  13   a  of the catching mechanism  13 . At this time, if the contact pressure of the gasket  15   b  to the partition wall  13   a  becomes needlessly high, the base  12  is bent higher in a periphery area than the partition wall  13   a , and hence there is a possibility that the airtightness by the gasket  15   a  deteriorates. Nevertheless, if the height of the partition wall  13   a  is made to be lower than the height of the peripheral wall  12   a , there is not a possibility that the airtightness by the gasket  15   b  deteriorates because the contact pressure by the gasket  15   a  against the peripheral wall  12   a  becomes dominant over the contact pressure by the gasket  15   b  against the partition wall  13   a . Hence, it is desirable to set the height of the partition wall  13   a  of the catching mechanism  13  lower than that of the peripheral wall  12   a  of the base  12 . 
     In the embodiment shown in FIG. 5B, assuming that the height of the gaskets  15   a  and  15   b  is equal, the height of the partition wall  13   a  is made to be low than that of the peripheral wall  12   a . Nevertheless, assuming that the height of the peripheral wall  12   a  and partition wall  13   a  is equal, as shown in FIG. 5C, by setting the height of the gasket  15   b , closely contacted to the partition wall  13   a , lower than that of the gasket  15   a  closely contacted to the peripheral wall  12   a , it is possible to obtain an effect similar to that in FIG.  5 B. 
     In the above-described HDD  10 , the gasket  15  is bonded with adhesive on the top cover  14 . Nevertheless, it is sufficient as the gasket  15  that the gasket  15  intervenes between the peripheral wall  12   a  of the base  12  and the top cover  14  and can keep the internal airtightness of the HDD  10 . Hence, the gasket  15  can be bonded on the top face of the peripheral wall  12   a  of the base  12 , or can be located between the base  12  and top cover  14  without bonding the gasket  15  on the base  12  or top cover  14 . 
     Furthermore, in the HDD  10 , the gasket  15   b  is unified with the gasket  15 . Nevertheless, in case of considering only having an effect of the enhancement of a dust collection efficiency, as shown in FIG. 7, it is possible to make the gasket  15   b  separate from the gasket  15 . At this time, the material of the gasket  15   b  need not be the same as that of the gasket  15 . It may be material that exists between the partition wall  13   a  and top cover  14  and can isolate the catching chamber  13   e  from the disk container  12   b . Nevertheless, there are advantages that, by unifying the gasket  15   b  with the gasket  15 , it is possible to produce the gasket  15  including the gasket  15   b  in one formation process, and also to simplify adhesion work to the top cover  14 . 
     Furthermore, in the HDD  10 , the gasket  15   b  is contacted to a top face of the partition wall  13   a . Nevertheless, it is sufficient in the present invention that the airtightness of the catching chamber  13   e  can be secured in a radial direction of the magnetic disk  22 . Therefore, the contact relation between the gasket  15   b  and partition wall  13   a , as shown in FIG. 5B or FIG. 5C, is not limited to the configuration that the gasket  15   b  is contacted to the top face of the partition wall  13   a . For example, as shown in FIG. 8B, it is possible to enjoy effects of the present invention also by the configuration that the gasket  15   b  is contacted to the side face of the partition wall  13   a.    
     Moreover, although the gasket  15   b  made of fluororubber is exemplified in this embodiment, it is possible to adequately select other material. If the base  12  is made by die casting where high accuracy cannot expect, it is desirable to make gasket  15   b  with material having enough elastic force. If high precision can be obtained, the gasket  15   b  can be also configured with metal material having higher rigidity than rubber. In this case, for example, as show in FIG. 8B, it is possible to make the configuration that the metal gasket  15   b , unified with the top cover  14 , is inserted into a groove formed in a top section of the partition wall  13   a.    
     The present invention has several advantages. As described above, the present invention can provide a disk drive apparatus where a dust collection efficiency is improved. This disk drive apparatus enhances the performance of a disk drive apparatus by reducing a collision probability of a data read/write head and dust in connection with acceleration of high-speed rotation of a disk that is a storage medium. 
     While the invention has been shown or described in only some of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the scope of the invention.