Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the record
Reexamination Certificate
1998-07-22
2001-05-15
Faber, Alan T. (Department: 2651)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the record
C360S099050, C360S069000, C360S060000
Reexamination Certificate
active
06233110
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a disc driving device for recording/reproducing information signals on or from a recording disc, such as a so-called floppy disc.
2. Related Art
There has so far been proposed a recording disc, such as a so-called floppy disc, constituted by a thin disc-shaped disc substrate on which is applied a recording layer, such as a magnetic layer. This recording disc is rotatably housed in a cartridge and used in this state. There has also been proposed a disc driving device adapted for recording/reproducing information signals using this recording disc as a recording medium.
In such disc driving device, the recording disc has its center hub of metal held by a disc table and is run in rotation by a spindle motor along with the disc table. The disc table has on its major surface a magnet for attracting the hub, a spindle shaft inserted into a center hole bored in the center portion of the hub and a chuck pin adapted to be inserted into a chuck hole bored in the hub at a pre-set separation from the center hole. The chuck pin is movable with respect to the major surface of the disc table. The inner diameter of the chuck hole is selected to be larger than the outer diameter of the chuck pin. If the disc table is run in rotation, with the spindle shaft inserted into the center hole, there is produced a rotational torque relative to the disc table by the load against rotation of the recording disc. The operation of inserting the spindle shaft in the center hole and of inserting the chuck pin in the chuck hole is herein termed a chuck operation. If the rotational torque is produced relative to the disc table, the chuck pin is moved relative to the spindle shaft by the inner edge of the chuck hole for centering the recording disc relative to the spindle shaft by the spindle shaft and the chuck pin.
For this recording disc, information signals are recorded or read out by a head device which is biased by a biasing member towards the major surface of the recording disc. This type of the disc driving device is disclosed in, for example, U.S. Pat. No. 5,166,846 or in U.S. Pat. No. 5,126,900.
In such recording disc, it is desired to increase the recording capacity and investigations for increasing the information recording density are proceeding. If the recording layer is a magnetic layer, the magnetic layer needs to be reduced in thickness for increasing the information recording density. If the recording layer is reduced in thickness, the force of biasing the magnetic head against the major surface of the magnetic disc, that is the head loading pressure, needs to be decreased in view of durability of the recording layer.
The reason is that if the recording layer is reduced in thickness with the head loading pressure remaining unchanged, the magnetic layer tends to be destroyed when the magnetic head is contacted with the major surface of the recording disc, as when rotation of the recording disc is stopped.
For increasing the recording density, it is possible to cause the recording head to fly relative to the recording disc, as is done in a hard disc drive, in order to prevent possible destruction of the major surface of the recording disc completely. In this case, it is also necessary to decrease the head loading pressure.
If, in a recording disc, the transfer speed of the information signals to be recorded or reproduced is to be increased, the rotational velocity has to be increased.
Meanwhile, in a disc driving device in which the head loading pressure is decreased for enabling the use of the recording disc having the magnetic layer reduced in thickness for increasing the density of the information signals, the load against rotation of the recording disc due to the head loading pressure is decreased. The result is that, when loading the conventional recording disc on this type of the disc driving device, there is a risk that the sufficient rotational torque with respect to the disc table on rotation of the disc table cannot be developed, such that the recording disc cannot be centered correctly. Specifically, the load against rotation of the recording disc is the sum of the torque T(h) produced by the contact of the magnetic head with the recording disc and the torque T(s) generated on contact with the recording disc of a liner provided in the cartridge. If this load (T(h)+T(s)) is smaller than the rotational torque T(c) of the recording disc relative to the disc table, required for centering the recording disc, the recording disc cannot be centered even if the disc table is run in rotation. The rotational torque T(c) required for centering the recording disc is of the order of approximately 15 gfcm. That is, for optimum centering and chucking of the recording disc, (T(h)+T(s))>T(c)=15(gfcm) represents a necessary condition.
With the above-described disc driving device, since the torque T(h) produced on contacting of the magnetic head with the recording disc is small, there is a risk that (T(h)+T(s))<T(c)=15(gfcm)
On the other hand, for using a recording disc capable of recording a large quantity of the information, it is desirable to rotate the disc table at a velocity higher than in the conventional system. If, in this case, the disc table is run in rotation at a high rotational velocity before completely loading the recording disc, there is a risk that the recording disc cannot be chucked reliably by the disc table.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a disc driving device in which, when the head loading pressure is decreased for enabling the use of recording disc having the magnetic layer reduced in thickness for increasing the information recording density, the recording disc can be chucked reliably, and in which, if a conventional recording disc is used, the disc can be centered and chucked satisfactorily.
In one aspect, the present invention provides a disc driving apparatus for removably accommodating a disc-type recording medium, in which the apparatus includes a hub having a center opening and a chuck hole at a pre-determined distance from the center opening, and a recording disc attached to the hub. The disc driving apparatus also includes a disc table having a major surface for loading the hub of the recording disc thereon, a spindle shaft provided on the major surface of the disc table and adapted for being fitted in the center opening in the hub, a chuck member provided on the major surface of the disc table for rotation relative to the major surface and adapted for being fitted in the chuck hole in the hub, a spindle motor for rotating the disc table, a head for recording/reproducing information signals for the recording disc loaded on the disc table, loading means for moving the recording disc between a loading position and an unloading position, and control means for controlling a rotational velocity of the disc table. The control means controls the spindle motor so that, when the recording disc is moved by the loading means to the loading position, the recording disc is rotated at a first rotational velocity during a first period and subsequently at a second rotational velocity slower than the first first rotational velocity.
In another aspect, the present invention similarly provides a disc driving apparatus for removably accommodating a disc-type recording medium, in which the apparatus includes a hub having a center opening and a chuck hole at a pre-determined distance from the center opening, and a recording disc attached to the hub. The disc driving apparatus also includes a disc table having the major surface for loading the hub of the recording disc thereon, a spindle shaft provided on the major surface of the disc table and adapted for being fitted in the center opening, a chuck member provided on the major surface of the disc table for rotation relative to the major surface and adapted for being fitted in the chuck hole in the hub, a spindle motor for rotating the disc table, a head for recording/reprodu
Faber Alan T.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Sony Corporation
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