JPH01205758A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To achieve a prescribed revolving speed of a magnetic disk in a short time with simple constituiton and to attain a large capacity by enlarging torque until the magnetic disk reaches the prescribed revolving speed and keeping constant torque after reaching the prescribed revolving speed. CONSTITUTION:When the title device is started up, a relay 6 is changed over to a terminal 4 side by a control circuit 7. Consequently, a main coil 9 is inserted with a starting coil 10 to enlarge the torque. Afterward, when the circuit 7 detects that a spindle motor 1 reaches its steady revolving speed, the relay 6 is changed over to a terminal 2 side. In this case, since a driving electric current from a driving circuit 8 into the motor 1 flows individual main coils 9 only, a counter-electromotive force is small, and hence a current fluctuation to be supplied from a constant-voltage power source is little. Therefore, the prescribed revolving speed is achieved in a short time and then maintained constantly, thus ensuring a large capacitorization.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a magnetic disk device having a storage function, which is provided in an electronic device such as a computer.

(Prior Art) Generally, an electronic device such as a computer includes a keyboard having an input function, a main unit having an editing/configuring function, a display device and a printing device having an output function, and a magnetic device having a storage function. A disk device is also provided.

For example, a hard disk type magnetic disk device having a storage function has 3-inch, 5-inch, 5.25-inch, 8-inch, etc. magnetic disks stacked at intervals, and a corresponding one for each magnetic disk. A plurality of magnetic heads are respectively provided.

Each magnetic disk is attached to a rotating shaft (hereinafter referred to as spindle shaft) of a direct drive DC motor (hereinafter referred to as spindle motor), and when recording or reproducing information, it takes a certain amount of time from startup to steady rotation. It is designed to rotate at a stable rotation speed without fluctuation during steady rotation.

Incidentally, in recent years, the capacity of the above-mentioned magnetic disk devices has been increasing, and in order to achieve this, there is a tendency to increase the number of magnetic disks per spindle shaft. As a result, the load on the spindle shaft increases, and a larger starting torque is required to maintain steady rotation of the magnetic disk within a certain period of time.

In general, spindle motors are designed to drive the magnetic disk most efficiently during steady rotation, so
It is not possible to increase only the starting torque.

That is, the starting torque T is calculated as follows: T-BIIN-1...・
...(1) (However, the width of the coil that crosses the magnetic flux from the magnet is constant).

As is clear from the above equation (1), the starting torque T increases by increasing the magnetic flux density B or the number of turns N of the coil. However, as the rotation speed increases, the relative speed V between the magnet and the coil increases, and the BN
The back electromotive force Eemf generated in proportion to v increases.

As a result, the current supplied to the coil from the power source with a constant voltage decreases, resulting in a decrease in the starting torque T.

Therefore, there is a problem in that the magnetic disk cannot reach its rated rotational speed.

(Problem M to be Solved by the Invention) In view of the above-mentioned problems, an object of the present invention is to provide a magnetic disk device that can reliably rotate a magnetic disk at a predetermined number of rotations with a simple configuration. .

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a magnetic disk on which information is recorded, a head for recording or reproducing information on the magnetic disk, A drive motor rotates a magnetic disk at a predetermined rotation speed, and the torque of this drive motor is adjusted so that the magnetic disk rotates at a predetermined rotation speed so that a torque larger than the predetermined torque is output until the magnetic disk reaches a predetermined rotation speed. The present invention is characterized by comprising a control means for controlling such that a predetermined torque is output when the rotational speed is reached.

(Function) In the present invention, the torque of the drive motor is adjusted such that a torque larger than the predetermined torque is output until the magnetic disk reaches a predetermined rotation speed, and when the magnetic disk reaches a predetermined rotation speed. Since the control is performed so that a predetermined torque is output, the magnetic disk can be reliably rotated at a predetermined rotation speed with a simple configuration.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an example of the benefits when applied to a hard disk type magnetic disk device.

As shown in the figure, the magnetic disk device includes a three-phase spindle motor 1 having a magnet (not shown);
Connecting wires 3.3, . . . connected to the spindle motor 1 and having a connecting terminal 2, and connecting wires 5.5, . A switching relay 6 is provided. In addition, magnetic disk devices include magnetic disks (
A control circuit 7 detects the rotation speed (here, it refers to the relative speed between the coil and magnet of the spindle motor) of the spindle motor (not shown) and controls the switching operation of the relay 6, and a drive circuit 8 drives the spindle motor 1. It is equipped.

The spindle motor 1 includes a main winding 9.9 that is always used.
. . . and starting windings 10, 10, . . . connected in series with each main winding 9 and used only at startup.・Then, each connection line 3 mentioned above is
They are connected between the main winding 9 and the starting winding 10, respectively.

Next, the operation of the above-described magnetic disk device will be explained using FIG. 2.

First, when starting up the magnetic disk device, the control circuit 7 switches the relay 6 to the connection terminal 4 side. At this time, if the number of windings of each main winding 9 is Nc%, and the number of windings of each starting winding 10 is Ns, the total number of windings is Nc.
It becomes +Na.

Therefore, the starting torque T at this time is T-mB・(Nc1NS)Φi becomes.

Thereafter, the control circuit 7 controls the relative speed between each main winding 9 and each starting winding 10 of the spindle motor 1 and the magnet, that is, the magnetic disk reaches steady rotation (point p in FIG. 2(a)). When this is detected, the relay 6 is switched to the connection terminal 2 side (point q in (b>) in the figure).

At this time, the drive circuit 8 flowing into the spindle motor 1 side
Since the drive current flows only to each main winding 9, the back electromotive force Eemf generated in each main winding 9 is vB (Nc +
Na) becomes a value corresponding to vBNc, and as a result, the current supplied from the power source with a constant voltage does not decrease, so that the predetermined rotational speed of the magnetic disk is maintained.

[Effects of the Invention] As explained above, the magnetic disk device of the present invention can reliably rotate the magnetic disk at a predetermined rotation speed with a simple configuration, thereby increasing the capacity of the magnetic disk device. be able to.

[Brief explanation of the drawing]

Fig. 1 is a circuit configuration block diagram showing an example in which the present invention is applied to a hard disk type magnetic disk device, and Fig. 2 (
FIGS. 8A and 7B are diagrams showing the relay switching at different rotational speeds of the magnetic disk. 1...Spindle motor, 6...Relay, 7...
Control circuit, 8... Drive circuit, 9... Main winding, 10.
...Starting winding 10° Applicant Toshiba Corporation Representative Patent attorney Sasu Suyama -

Claims (1)

[Claims] (1) A magnetic disk on which information is recorded, a head that records or reproduces information on the magnetic disk, a drive motor that rotates the magnetic disk at a predetermined number of rotations, and a torque of the drive motor that is controlled by the Control so that a torque larger than a predetermined torque is output until the magnetic disk reaches a predetermined rotation speed, and a predetermined torque is output when the magnetic disk reaches a predetermined rotation speed. A magnetic disk device characterized by comprising: means.