Abstract:
A cover seal seals an opening of a housing body and encloses a cover for the opening in cooperation with the housing body. The rigidity of the cover seal is reinforced by a metallic sheet or a multiplayer synthetic resin sheet, so that vibration of the cover seal is prevented even if air stream in a seam between the housing body and cover acts on the cover seal from the behind.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an information recording apparatus such as a hard disk drive unit (HDD), and more particularly, to a cover seal covering over a seam provided between an edge around an opening of a housing and a cover for closing the opening. 
     The term “seam” is referred to in this specification as a portion between the edge and the cover, with or without a gap therebetween. 
     2. Description of the Prior Art 
     It is well known that an HDD employs a cover of a vibration suppression metallic plate so as to reduce noise during reading/writing operation for data. The cover is coupled to a housing body of a box-shape in the HDD for providing a housing. The housing of this type may contribute to reduction in noise by the effect of the vibration suppression metallic plate. 
     A housing of an HDD should air-tightly enclose a magnetic disk and a magnetic head. For example, in case where a housing is comprised of a pair of members such as a box-shaped housing body and a cover of a vibration suppression metallic plate, a cover seal is adhered to air-tightly close the opening of the housing body. The housing body and cover seal serve to enclose the cover, so that a seam between the housing body and cover is sealed. Since the cover seal can contribute to cost reduction as compared with a packing, the cover seal comes to take the place of the packing as a seal member. 
     The present inventors have discovered that air flows in the seam between the housing body and cover so that the air causes the cover seal to vibrate during reading/writing operation for data. The present inventors have confirmed that the vibration of the cover seal takes part in noise of the HDD. 
     SUMMARY OF THE INVENTION 
     It is accordingly an object of the present invention to provide a cover seal for an information recording apparatus capable of reducing noise of the apparatus. 
     According to a first aspect of the present invention, there is provided a cover seal comprising: a metallic sheet; and an adhesive layer formed on a side face of the sheet for adhering the sheet on a housing for an information recording apparatus. 
     The rigidity of the cover seal may be reinforced by the metallic sheet, so that the cover seal can be prevented from vibrating. Accordingly, noise caused by vibration of the cover seal can be reduced. The metallic sheet of the cover seal may be covered with a protection layer of a synthetic resin. 
     The cover seal is employed in an information recording apparatus. The information recording apparatus may comprise a housing body accommodating at least a recording disk and a head, and a cover plate closing an opening of the housing. The metallic sheet of the cover seal preferably covers over at least a seam between an edge around the opening and the cover. The adhesive layer of the cover seal serves to adhere the metallic sheet on the edge and a surface of the cover. Accordingly, even if air stream in the seam acts on the cover seal from the back, the cover seal can be prevented from vibrating, so that the generation of noise can be suppressed. The cover seal may cover all over the cover so as to enclose the cover in the housing body and the cover seal itself. 
     According to a second aspect of the present invention, there is provided a cover seal comprising: a multilayer synthetic resin sheet having an interposed adhesive layer; and an adhesive layer formed on a side face of the sheet for adhering the sheet on a housing for an information recording apparatus. The multilayer structure may reinforce the rigidity of the cover seal, so that the same effect as the first aspect can also be achieved. 
     It should be noted that an information recording apparatus employing the cover seal according to the first or/and second aspect may be installed in a computer apparatus, or may be constructed as a stand-alone exterior recording apparatus. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiment in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a block diagram schematically illustrating the structure of a computer apparatus; 
     FIG. 2 is an exploded perspective view of a hard disk drive unit (HDD); 
     FIG. 3 is an enlarged partial view illustrating the section taken along the line  3 — 3  in FIG. 2; 
     FIG. 4 illustrates the structure of a cover seal according to a first embodiment of the present invention; and 
     FIG. 5 illustrates the structure of a cover seal according to a second embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 schematically illustrates the structure of a computer apparatus CO. The computer apparatus CO comprises a computer unit  13  assembled with a central processing unit (CPU)  11 , and a hard disk drive unit (HDD)  12  as an information recording apparatus of the present invention. The CPU  11  is capable of sending and receiving information data to and from the HDD  12  in accordance with instructions input from an input device  14 , such as a keyboard and/or a mouse, which is connected to the computer unit  13 . The information data may be displayed on a screen of a display device  15  which is connected to the computer unit  13 . 
     FIG. 2 illustrates an exploded perspective view of the HDD  12 . As shown in FIG. 2, the HDD  12  comprises a box-shaped housing body  20  as a member of a housing  19 . The housing body  20  is for example formed by aluminum die-casting into a box-shape so as to have a high rigidity. 
     The housing body  20  accommodates a plurality of magnetic disks  21  as recording media for recording information data, and magnetic heads  22  as reading/writing means opposed to the disk surfaces of the respective recording disks  21 . The recording disks  21  may rotate about a rotation axis  24  fixed to the housing body  20 . The rotation of the disks  21  is driven by a spindle motor, not shown. A carriage  25 , with the magnetic head  22  at the tip end, may swing about a carriage axis  27  fixed to the housing body  20 . The swinging movement of the carriage  25  is caused by a magnetic circuit  26  comprising an actuator. The magnetic heads  22  are positioned to a target recording track and block through the rotation of the disks  21  and the swinging movement of the carriage  25 . 
     A cover plate  30  closes a housing opening  29  of the housing body  20 . The cover  30  is coupled to the housing body  20 , by screws  31  positioned at four corners of the cover  30 , so as to form the housing  19 . Screw receiving recesses  32  are formed at the corners of the cover  30  so as to prevent the heads of the screws  31  from protruding from the level of the surface of the cover  30 . Steps  34  are formed on the housing body  20  inside a housing edge  33  at the corners for receiving the screw receiving recesses  32  of the cover  30 . When the steps  34  receive the screw receiving recesses  32 , the surface of the cover  30  is leveled with the housing edge  33 . Moreover, the heads of the screws  31  are prevented from protruding from the surface of the cover  30 . 
     When the cover  30  is coupled to the housing body  20 , two connecting screws  35  are screwed into the tip ends of the rotation axis  24  and the carriage axis  27 . Connecting screw receiving recesses  36  are formed in the cover  30  so as to prevent the heads of the connecting screws  35  from protruding from the level of the surface of the cover  30 . 
     The cover  30  may be formed by a press from an aluminum plate or a vibration suppression metallic plate. The press shapes the screw receiving recesses  32  and the connecting screw receiving recesses  36  on the cover  30 . The vibration suppression metallic plate may be a VEM comprising a vibration suppression material layer such as synthetic resin layer interposed between a pair of steel sheets. 
     When the attachment of the cover  30  is completed, a cover seal  38  is adhered to the outer surface of the housing  19 . The cover seal  38  not only covers all over the surface of the cover  30  as is apparent from FIG. 2 but also extends to the edge  33  of the housing body  20  as shown in FIG.  3 . Accordingly, a seam  39  between the edge  33  and the cover  30  is air-tightly sealed by the cover seal  38 . When the cover seal  38  is adhered all along the edge  33 , the cover  30  is enclosed in the cover seal  38  and the housing body  20 . The heads of the screws  31  in the screw receiving recesses  32  and the heads of the connecting screws  35  in the connecting screw receiving recesses  36  are positioned inside the cover seal  38 . 
     FIG. 4 illustrates the structure of a cover seal  38   a  according to a first embodiment of the present invention. The cover seal  38   a  comprises a metallic sheet  41  and an adhesive layer  42  formed on a rear face of the sheet  41 . The metallic sheet  41  may have rigidity enough to keep its shape by itself. The sheet  41  is for example made of an aluminum film or a copper film. The adhesive layer  42  serves to adhere the metallic sheet  41  on the cover  30  and the edge  33  of the housing body  20 . A PET (polyethylene terephthalate) protection layer  43  is formed on the front face of the metallic sheet  41  as a protection layer of a synthetic resin. The protection layer may be made from other synthetic resin in place of PET. 
     Assume that air stream  45  flows in the seam  39  between the housing body  20  and the cover  30  shown in FIG.  3 . The air stream  45  acts on the rear surface of the cover seal  38 . However, the cover seal  38  reinforced by the rigidity of the aluminum or metallic sheet  41  is prevented from vibrating, so that noise transmitted to the outside can be reduced. According to an experiment managed by the present inventors, the employment of the cover seal  38   a  achieves the noise level of 39 dB, while a conventional cover seal comprising a PET layer of 50 micrometers thickness and an adhesive layer of 30 micrometers thickness achieves the noise level of 41 dB. The cover seal  38   a  in the experiment has an aluminum or metallic sheet  41  with thickness b=50 micrometers, an adhesive layer  42  with thickness c=50 micrometers, and a PET protection layer  43  with thickness a=28 micrometers, as shown in FIG.  4 . The PET protection layer includes an adhesive layer of 5 micrometers for adhering the PET protection layer  43  to the aluminum or metallic sheet  41 . 
     The description will be made for a manufacture process of the cover seal  38   a  referring to FIG.  4 . First of all, an aluminum sheet  41  is prepared and predetermined characters may be printed on a surface of the sheet  41 . An adhesive and a PET sheet are then placed on the printed surface of the sheet  41 . When heat and pressure are applied with a heat roller to the printed surface, a PET protection layer  43  is formed on the sheet  41 . An adhesive layer  42  is then applied to the rear surface of the sheet  41  by using a roller or the like. A peel sheet is attached to the rear surface over the applied adhesive layer  42 . The cover seal  38   a  can be punched out of the sheet  41 . In use, the peel sheet is peeled off and the cover seal  38   a  is placed on a surface of the housing  19  with the adhesive layer  42  facing the surface. 
     As shown in FIG. 2, an inspection hole  44  may be bored in the cover seal  38   a . A communication hole  30   a  is formed in the cover  30  corresponding to the inspection hole  44 . These inspection hole  44  and communication hole  30   a  can be used when the air-tightness of the housing  19  is examined. Specifically, the examination can be conducted by first blowing air into the housing  19  through the inspection hole  44  and communication hole  30   a  and then detecting a leakage of air from the periphery of the cover  30  and the vicinity of the screws  31  and the connecting screws  35 . The communication hole  30   a  may be sealed by a seal member after the examination. The examination may be conducted during or after the assembling process of the HDD  12 . 
     FIG. 5 illustrates the structure of a cover seal  38   b  according to a second embodiment of the present invention. The cover seal  38   b  comprises a multilayer synthetic resin sheet  46  and an adhesive layer  47  formed on a rear surface of the synthetic resin sheet  46 . The rigidity of the synthetic resin sheet  46  is reinforced by a pile of first and second synthetic resin sheets  48 ,  49  with an adhesive layer  50  interposed therebetween. The first and second synthetic resin sheet  48 ,  49  may be made from PET material. The adhesive layer  47  serves to adhere the multilayer synthetic resin sheet  46  on the cover  30  and the edge  33  of the housing body  20 . 
     According to an experiment managed by the present inventors, the employment of the cover seal  38   b  achieves the noise level of 40 dB, while a conventional cover seal comprising a PET layer of 50 micrometers thickness and an adhesive layer of 30 micrometers thickness achieves the noise level of 41 dB. The cover seal  38   b  in the experiment has a first synthetic resin sheet  48  with thickness d=50 micrometers, a second synthetic resin sheet  49  with thickness f=50 micrometers, an adhesive layer  50  with thickness e=30 micrometers, and an adhesive layer  47  with thickness g=30 micrometers.