Abstract:
Disclosed is a magnetic disk apparatus comprising: a disk enclosure; a first printed-circuit board which is paired with the disk enclosure; and a second printed-circuit board which is connected to the first printed circuit board via a cable and is separated from the first printed-circuit board in structure; wherein the first printed-circuit board mounts circuits which are poor in noise resistance property, and a circuit which holds parameters unique to the disk enclosure; and wherein the second printed circuit board mounts circuits which are superior in noise resistance property.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a magnetic disk apparatus and in particular, to the magnetic disk apparatus reduced in costs with miniaturized and diversified printed-circuit boards. 
   2. Description of the Prior Art 
   A conventional magnetic disk apparatus generally has a single printed-circuit board for a single disk enclosure. The single printed-circuit board mounts all the circuits for controlling the disk enclosure. 
   In case of exchanging a conventional magnetic disk apparatus to another conventional magnetic disk apparatus for the purpose of increasing the capacity of the magnetic disk apparatus constituting a system or preserving the former magnetic disk apparatus as a spare magnetic disk apparatus, the printed-circuit board as well as the disk enclosure are exchanged for another set, because the printed circuit board and the disk enclosure are incorporated in one. 
   Referring to  FIG. 5 , disk enclosure  82  comprises a storage medium (not shown), a spindle motor (not shown) for rotating the storage medium, a voice coil motor (not shown) for driving a magnetic head (not shown) and rotating an actuator (not shown), a carriage (not shown) for carrying the magnetic head, a base (not shown) for mounting the storage medium, and a recording/reproduced signal compensation circuit (not shown) for processing a record/reproduced signal to/from the magnetic head. The magnetic head is mounted on the carriage. 
   Recording/reproduction of a signal to/from the storage medium is performed by the recording/reproduced signal compensation circuit and the magnetic head under the control of recording/reproducing control circuit  83  mounted on printed-circuit board  81 . SPM/VCM (Spindle Motor/Voice Coil Motor) control circuit  88  controls the rotation of the storage medium through the spindle motor and the position of the magnetic head through the voice coil motor. Interface control circuit  87  controls communication protocols with upper system  90  which are exchanged through connectors  89  and  91  and a bus cable therebetween. Parameter-holding circuit  86  holds parameters of the storage medium which correspond to a type of recording system and is such as a ROM. Analog/digital converter  84  converts an analog signal reproduced from the storage medium into a digital signal. Processor  85  controls recording/reproducing control circuit  83 , parameter-holding circuit  86 , interface control circuit  87 , and SPM/VCM control  88 . 
   As explained above, the conventional magnetic disk apparatus has a single printed-circuit board for a single disk enclosure. Therefore, in case of exchanging a conventional magnetic disk apparatus to another conventional magnetic disk apparatus, it is inevitable to exchange a printed-circuit board which is originally needless to be exchanged in addition to a disk enclosure, which results in an increase in cost of the exchange. 
   In case of a removable medium, after purchasing one removable medium and a recording/reproduction device, it is needed to purchase only another removable medium to increase the capacity. Therefore, the removable medium has a merit in capacity/cost ratio. On the other hand, in case of a magnetic disk apparatus, it is needed to purchase not only a disk enclosure but also a printed-circuit board which is unrelated to the increase of the capacity to increase the capacity. 
   In addition, the structure of a conventional disk apparatus in which a single printed-circuit board mounting all the circuits is combined with a single disk enclosure is a factor which prevents miniaturization of the apparatus and a breakaway of the apparatus from form factors. 
   SUMMARY OF THE INVENTION 
   In order to overcome the aforementioned disadvantages, the present invention has been made and accordingly, has an object to reduce the unit cost of a magnetic disk apparatus by dividing a printed-circuit board into function blocks and mounting only a circuit for holding parameters unique to a disk enclosure and circuits which are poor in noise resistance property on the printed-circuit board which is combined with the disk enclosure. 
   The present invention has another object to miniaturize a magnetic disk apparatus and to provide a form of the magnetic disk apparatus which is not restricted by form factors. 
   According to an aspect of the present invention, there is provided a magnetic disk apparatus comprising: a disk enclosure; a first printed-circuit board which is paired with the disk enclosure; and a second printed-circuit board which is connected to the first printed circuit board via a cable and is separated in structure from the first printed-circuit board; wherein the first printed-circuit board mounts circuits which are poor in noise resistance property, and a circuit which holds parameters unique to the disk enclosure; and wherein the second printed circuit board mounts circuits which are superior in noise resistance property. 
   The circuits which are poor in noise resistance property may include recording/reproduction control circuit. 
   The circuits which are poor in nose resistance property may include an analog/digital converter. 
   The circuits which are superior in noise resistance property may include an interface control circuit with an upper system. 
   The circuits which are superior in noise resistance property may include a processor. 
   The circuits which are superior in noise resistance property may include a spindle motor/voice coil motor control circuit. 
   The first printed-circuit board may further mount a elastomer connector. 
   The circuits which are superior in noise resistance property may include plural spindle motor/voice coil motor control circuits. 
   The circuits which are superior in noise resistance property may further include a single processor. 
   The circuits which are superior in noise resistance property may further include an interface circuit with an upper system. 
   The circuits which are superior in noise resistance property may further include a switch for selecting either of a first group consisting of a disk enclosure and a first printed-circuit board and a second group consisting of another disk enclosure and another first printed-circuit board. 
   The second printed-circuit board may be separated into a third printed circuit board and a fourth printed circuit; wherein the third printed circuit board may mount the interface control circuit; and wherein the fourth printed circuit board may mount the circuits which are superior in noise resistance property other than the interface control circuit. 
   The second printed-circuit board may not mount an interface control circuit. 
   The circuits which are superior in noise resistance property may include a processor. 
   The circuits which are superior in noise resistance property may include a spindle motor/voice coil motor control circuit. 
   These and other objects, features and advantages of the present invention will become more apparent in the light of the following detailed description of the best mode embodiments thereof, as illustrated in the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block diagram showing the structure of a magnetic disk apparatus according to a first embodiment of the present invention; 
       FIG. 2  is a block diagram showing the structure of a magnetic disk apparatus according to a second embodiment of the present invention; 
       FIG. 3  is a block diagram showing the structure of a magnetic disk apparatus according to a third embodiment of the present invention; 
       FIG. 4  is a block diagram showing the structure of a magnetic disk apparatus according to a fourth embodiment of the present invention; and 
       FIG. 5  is a block diagram showing the structure of a conventional magnetic disk apparatus. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Preferred modes of embodiment according to the present invention will be described with reference to the accompanying drawings. 
   Embodiment 1 
   Referring to  FIG. 1 , printed-circuit board  1  is combined with disk enclosure  2  in one-to-one relation. 
   Printed-circuit board  1  mounts connector  3 , parameter-holding circuit  4 , analog/digital converter  5 , and recording/reproduction circuit  6 . Connector  3  is coupled with connector  14  on printed-circuit board  13 . Parameter-holding circuit  4  holds parameters unique to disk enclosure  2 . Analog/digital converter  5  and recording/reproduction control circuit  6  are poor in noise resistance property. The functions of analog/digital converter  5  and recording/reproduction control circuit  6  are the same as those of analog/digital converter  84  and recording/reproduction control circuit  83 , respectively. 
   Printed circuit board  13  mounts connector  14 , processor  15 , interface control circuit  16 , connector  17 , and SPM/VCM control circuit  18 . The functions of processor  15 , interface control circuit  16 , connector  17 , and SPM/VCM control circuit  18  are the same as those of processor  85 , interface control circuit  87 , connector  89 , and SPM/VCM control circuit  88 , respectively. Processor  15 , interface control circuit  16 , and SPM/VCM control circuit  18  are superior in noise resistance property. 
   Recording/reproduction circuit  6  is located in the neighbor of a magnetic head to prevent mixture of noise coming from the external into a reproduced signal because the reproduced signal is low in level and high in frequency. Parameter-holding circuit  4  holds parameters which are unique to disk enclosure  2  such as the number of disks, the material of the disks, the speed of revolution of the disks, the number of tracks per disk, and track pitch of the disks. 
   Interface control circuit  16  is in conformity with IDE (Integrated Device Electronics), SCSI (Small Computer Systems Interface) or the like, and is not preferably restricted by types of upper system  19 . 
   Disk enclosure  2  comprises a storage medium (not shown), a spindle motor (not shown) for rotating the storage medium, a voice coil motor (not shown) for driving a magnetic head (not shown) and rotating an actuator (not shown), a carriage (not shown) for carrying the magnetic head, a base (not shown) for mounting the storage medium, and a recording/reproduced signal compensation circuit (not shown) for processing a record/reproduced signal to/from the magnetic head. The magnetic head is mounted on the carriage. 
   Recording/reproduction of a signal to/from the storage medium is performed by the recording/reproduced signal compensation circuit and the magnetic head under the control of recording/reproducing control circuit  6  mounted on printed-circuit board  1 . SPM/VCM control circuit  18  controls the rotation of the storage medium through the spindle motor and the position of the magnetic head through the voice coil motor. Interface control circuit  16  controls communication protocols with upper system  19  which are exchanged through connectors  17  and  20  and a bus cable therebetween. Upper system  19  outputs the data to be recorded in disk enclosure  2  and inputs the data reproduced from disk enclosure  2 . Processor  15  controls recording/reproducing control circuit  6 , parameter-holding circuit  4 , interface control circuit  13 , and SPM/VCM control  18 . 
   Because of the structure of the magnetic disk apparatus of this embodiment, in case of exchanging a magnetic disk apparatus of this embodiment to another magnetic disk apparatus of this embodiment, it is needless to exchange printed-circuit board  13  and it is only needed to exchange the set of printed-circuit board  1  and disk enclosure  2  to the set of printed-circuit board  7  and disk enclosure  8 . Therefore, the cost of the exchange is reduce by the cost of printed-circuit board  13  as compared with the conventional magnetic disk apparatus. In addition, the exchangeable part of the magnetic disk apparatus of this embodiment is miniaturized by the size of printed-circuit board  13  owing to the structure of the magnetic disk apparatus of this embodiment. Further, because parameter-holding circuit  4  and  10  hold parameters unique to disk enclosure  2  and  8 , respectively, and connectors  3  and  9  are elastomer connectors for easy attachment/detachment, the set of printed-circuit  1  and disk enclosure  2  can be easily exchanged to the set of printed circuit  7  and disk enclosure  8 . Still further, the forms of printed-circuit boards  1 ,  7 ,  13  are not restricted by form factors and free from old-fashioned forms. 
   Embodiment 2 
   The second embodiment is basically the same as the first embodiment, but more improved in a method of dividing printed-circuit boards than the first embodiment. 
   Referring to  FIG. 2 , printed-circuit board mounts SPM/VCM control circuit  24  and  25 , connectors  26 ,  27 , processor  28 , interface control circuit  29 , connector  30 , and switch circuit  31 . Each of exchangeable part  21  and  22  is composed of a disk enclosure, a board mounting a connector  34  or  35 , a parameter-holding circuit, an analog/digital converter, writing/reproduction control circuit  6 . Exchangeable part  21  is the same as a set of printed-circuit board  1  mounting the aforementioned parts and disk enclosure  2 , and exchangeable part  22  is the same as a set of printed-circuit  7  mounting the aforementioned parts and disk enclosure  8 . One processor  28  and one interface control circuit  29  correspond to two exchangeable parts  21  and  22 . 
   SPM/VCM control circuits  24  and  25  perform spindle motor control and voice coil motor control for exchangeable parts  21  and  25 , respectively. Switch  31  determines which of exchangeable parts  21  and  22  is selected. This embodiment has a configuration in which two SPM/VCM control circuit  24  and  25  and two connectors  26  and  27  are included. This configuration enables a single processor  28  to control two exchangeable parts  21  and  22 , whereby a capacity/cost ratio is improved. 
   Embodiment 3 
   A conventional magnetic disk apparatus consisting of a set of a disk enclosure and a single printed-circuit board is not compatible with plural types of interface format with an upper system. Therefore, if a type of interface format changes to another type of interface format, the whole of conventional magnetic disk apparatus must be exchanged to another conventional magnetic disk apparatus. This embodiment dissolves this disadvantage. 
   Referring to  FIG. 3 , a magnetic disk apparatus of this embodiment comprises disk enclosure  42 , and printed-circuit boards  41 ,  47 , and  52  or  56 . Printed-circuit board  41  mounts connector  50 , a parameter-holding circuit, an analog/digital converter, and recording/reproduction control circuit. Printed-circuit board  47  mounts connectors  48  and  51 , SPM/VCM control circuit  40 , and processor  49 . Printed-circuit board  52  mounts connectors  54  and  55 , and interface control circuit  53 . Printed-circuit board  56  mounts connectors  58  and  59 , and interface control circuit  57 . 
   Interface control circuit  53  and connector  54  are in conformity with an interface with upper system  60 . Interface control circuit  57  and connector  58  are in conformity with an interface with upper system  62 . Interface control circuit  53  controls the communication protocol with upper system  60  and interface control circuit  57  controls the communication protocol with upper system  62 . 
   When connecting a magnetic disk apparatus which consists of disk enclosure  42  and printed-circuit board  41 ,  47 , and  52  and is connected to upper system  60  to upper system  62  which has an interface different from that of upper system  60 , it is needless to exchange disk enclosure  42  and printed-circuit board  41  and  47  and it is only needed to exchange printed-circuit board  52  to printed-circuit board  56 . 
   Embodiment 4 
   Referring to  FIG. 4 , a magnetic disk apparatus of this embodiment comprises disk enclosure  42 , printed-circuit board  41 , and printed-circuit board  63 . Disk enclosure is the same as disk enclosure  2 . Printed-circuit board  41  is the same as printed-circuit board  1  and mounts a connector, a parameter-holding circuit, an analog/digital converter and recording/reproduction control circuit. Interface control circuit  79  is not mounted on printed-circuit board  63  but is incorporated in upper system  79 . 
   The operations of the analog/digital converter mounted on printed-circuit board  41 , the recording/reproduction control circuit mounted on printed-circuit board  41 , processor  64 , SPM/VCM control circuit  65 , interface control circuit  79  are the same as those of analog/digital converter  5 , recording/reproduction control circuit  6 , processor  15 , SPM/VCM control circuit  18 , and interface control circuit  16 , respectively, and explanations thereof are omitted. 
   Because interface control circuit  79  is incorporated in upper system  78 , the cost of the magnetic disk apparatus is reduced and the magnetic disk apparatus is miniaturized. 
   As explained above, according to the present invention, the cost of the magnetic disk apparatus is reduced, the magnetic disk apparatus is miniaturized, and the form of the magnetic disk apparatus is not restricted by form factors because of a basic structure in which a printed-circuit board is divided into function blocks. 
   In addition, the interface with an upper system can be easily changed because an interface circuit is separated. 
   Further, the magnetic disk apparatus can be easily exchanged to another one because a non-volatile memory is used for a parameter-holding circuit which holds parameters unique to a disk enclosure and an elastomer connector is used for a connector which connects printed-circuit boards together. 
   Although the present invention has been shown and explained with respect to the best mode embodiments thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omissions, and additions in the form and detail thereof may be made therein without departing from the spirit and scope of the present invention.