Dynamic magnetic information storage or retrieval – General recording or reproducing – Specifics of the amplifier
Reexamination Certificate
2001-07-12
2004-07-13
Hudspeth, David (Department: 2651)
Dynamic magnetic information storage or retrieval
General recording or reproducing
Specifics of the amplifier
C360S244100
Reexamination Certificate
active
06762896
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a storage media reading/writing system, specifically to a reading/writing semiconductor integrated circuit that amplifies a signal read from a head or drives the head by a write signal in the storage media reading/writing system of the magnetic recording system, which is a technique effective for use in a hard disk drive.
Generally, the hard disk drive is provided on the side of a carriage
130
, as shown in
FIG. 23
, with a reading/writing semiconductor integrated circuit (hereunder, referred to as read write IC)
220
that amplifies a signal read from a magnetic head or drives the magnetic head by a write signal to move an arm
120
furnished with the magnetic head for reading data stored in a magnetic disk
100
as storage media; and, the read write IC
220
and the magnetic head are connected usually with a bendable cable called the FPC (Flexible Printed Circuit). Further, in the hard disk drive containing plural magnetic disks as shown in
FIG. 23
, the read write IC is designed as an IC for multiple channels that processes, with one IC, the signals from the plural magnetic heads provided correspondingly with the plural magnetic disks each.
SUMMARY OF THE INVENTION
Differently from a semiconductor memory, the magnetic disk drive includes physically movable parts that delay the read and write speed of data, which is disadvantageous, and there is a demand for a still further increase in the speed. In order to enhance the data transfer speed in the magnetic disk drive, it is needed to increase the rotational speed of a disk, namely, a spindle motor, and also to accurately perform the servo control of a voice coil motor that moves the spindle motor and the carriage. Also, the read write IC is required for a high-performance circuit design, so as to amplify high frequency signals.
The applicant of this invention has succeeded in the development of a magnetic disk drive and a high-performance read write IC that permit such a high-speed rotation and an accurate servo control in the high-speed rotation and a high-frequency operation. However, the inventors found a problem that an increase of the data transfer speed will accompany a deterioration of the SN ratio relating to the read signal and the write signal. The inventors examined the cause and source of the problem, accordingly.
As the result, the inventors found that the noises of high-frequency components are created at the magnetic head (especially during writing), and in such a configuration that the read write IC is installed on the carriage and the magnetic head located on the front of the arm is connected to the read write IC with a cable, if the length of the cable is very long, it will function as an antenna to pick up high frequency noises; and the noises picked up by the cable deteriorate the SN ratio since a signal transmitted through the cable is very weak.
Accordingly, the inventors investigated the possibility of shortening the length of the cable that connects the magnetic head and the read write IC by installing the read write IC on the arm. However, the installation of the read write IC on the arm increases the weight of the arm, which interferes with the seek operation, and a large size IC is not permitted to be mounted on the arm. From such circumstances, the inventors reach an idea to divide the functions of the conventional read write IC into plural chips, and to install only the IC on the arm that is connected directly to the magnetic head and has a minimum configuration of a read amplifier and a write amplifier to electrically drive the head, whereby the aforementioned problem can be solved.
Now, in order to solve the problem similar to the above problem, the Japanese Published Unexamined Patent Application No. Hei 3(1991)-108120 discloses an IC that splits the read write IC and installs an IC including a control circuit on the side of the movable arm, and installs an IC chip having a write circuit or a read circuit on the side of the head slider. This prior art presents an example of an IC chip that reduces the load impedance of the write circuit to make a quick rise of the current, and has the write circuit to guarantee a good writing that is installed on the side of the head slider.
Further, this prior art describes that the wiring length between the head IC and the magnetic head has to be made as short as possible, since the noise level mixed in the reading signal is proportional to the wiring length between the head IC and the magnetic head and a longer wiring length produces larger noises. In other words, the prior art considers it desirable to provide an IC chip having a read circuit and a write circuit on the side of the head slider, in view of the characteristics of the read circuit and the write circuit; however, since such an arrangement increases the weight of the head slider to deteriorate the tracking ability, conceivably the invention proposes to provide the IC chip having the read circuit or the write circuit on the side of the head slider. At least, the prior art does not disclose at all the positive aspect of installing an IC chip having only the read circuit on the side of the head slider.
Further, in those days when the aforementioned prior art was proposed, the IC was sealed in a resin package in general, and there was not available a recently developed mounting technique that does not use a package, such as the flip chip. Therefore, the weight of the present IC is considerably reduced, compared to the times of the application of the prior art, and it becomes less significant in view of the weight to divide the read write IC into an IC chip including the control circuit installed on the side of the movable arm and an IC chip having the write circuit or the read circuit installed on the side of the head slider. In short, it is reasonable to understand the prior art, from the spirit of the invention to reduce the load impedance, as a technique maintaining it desirable to install an IC chip including the write circuit and the read circuit on the side of the head slider, when the problem of the weight is resolved.
However, the inventors of the present invention found a further problem that the installation of an IC chip having the write circuit and the read circuit on the side of the head slider, accompanying the adoption of the flip chip mounting technique, does not very much aggravate the tracking ability of the head, however the power consumption in the chip increases and generates more heat, whereby a suspending part of the head retaining means thermally deforms to deteriorate the positioning accuracy. Concretely, first the reading is executed in the write mode, and the positioning of the head is executed on the basis of the signal readout, and then the writing is started; however, provided that the write circuit is installed near the head, a great amount of currents flows during the writing to raise the temperature of the chip, which leads to a fear of thermally deforming the head suspending part, and finally dislocating the head.
Especially in the flip chip mounting technique, the thermal capacity of a chip diminishes by the extent that the chip does not wear a package, and the thermal transmission between the chip and the head suspending part is bettered in comparison to an IC sealed in a package; and therefore, the head suspending part becomes still easier to thermally deform (stretch and shrink). The aforementioned prior art does not disclose at all a conception of dividing the chip from the viewpoint of the thermal deformation of the head suspending part, accompanied with a heat generated in the chip.
It is therefore an object of the invention to provide a storage media reading/writing system that prevents a thermal deformation of the head suspending part due to the write current, and achieves a highly accurate writing and reading.
Another object of the invention is to provide a storage media reading/writing system that permits the reading of data at a high speed without lowering the SN ratio.
Another object of the
Fujii Noriyuki
Kobayashi Yoichiro
Shinomiya Toshio
Yoshinaga Masaki
Yoshizawa Hiroyasu
Davidson Dan I.
Hitachi , Ltd.
Mattingly Stanger & Malur, P.C.
LandOfFree
Storage media reading writing system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Storage media reading writing system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Storage media reading writing system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3241974