JPS6313167A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To obtain a rotational precision of a magnetic disk which is sufficient to secure the interchangeability between the recording and reproduction by using a step motor as the driving means of the magnetic disk and providing a large diameter fly-wheel which has a great mass of inertia in a spindle shaft. CONSTITUTION:The pulley 2 of the rotary shaft of the step motor 1 and the large diameter fly-wheel 3 which is die-casted with aluminium, steel, etc., attached to the spindle shaft 4A are connected with a belt 5 to constitute a decelerating means. The magnetic disk in a medium cassette 6 is driven to rotate by the driving pin 4B of the spindle 4 on the spindle shaft 4A directly connected to the fly-wheel 3. By a drive control circuit 12 consisting of a integrating circuit, etc., the excitation phase driving current of the step motor 1 is curvedly controlled in a waveform approximate to a since wave, so that the rotational characteristic of the step motor 1 becomes smooth and the fine fluctuation of its rotation can be reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic disk device, and particularly to a magnetic disk device that rotates a magnetic disk at a predetermined number of rotations and magnetically records and reproduces information on the magnetic disk. It is something.

[Prior Art] Magnetic disk drives are used as external storage devices for computer systems, word processors, and the like to store various types of information. 511 disk devices are fixed (hard) disk devices with a large-capacity magnetic disk fixedly installed inside the device, or elastic and flexible magnetic recording media stored in cassettes or jackets that can be replaced. Various methods are known, such as a floppy disk device that uses a floppy disk device.

In all of these devices, a disc-shaped magnetic recording medium is rotationally driven by a direct current motor using a direct drive motor 6 and a belt drive, and information is magnetically recorded and reproduced using a magnetic head.

[Problems to be Solved by the Invention] This type of device reproduces recorded information without error. Alternatively, in order to be able to correctly reproduce information recorded by another device, the magnetic disk needs to be accurately rotated at a certain rated rotational speed during operation.

For this reason, conventional devices use a rotary encoder or the like to detect the rotational speed of the magnetic disk and the motor that drives it, and perform closed-loop control in which this information is fed back to the motor drive control section. Therefore,
Conventional devices have had problems in that the control system has become complicated and manufacturing costs have increased.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a magnetic disk in which the magnetic disk is rotated at a predetermined number of rotations and magnetic information is recorded and reproduced on the magnetic disk. In the apparatus, a step motor is used as the magnetic disk drive means.

[Function] According to the above configuration, since the magnetic disk is driven by the step motor, it is possible to ensure sufficient magnetic disk rotation accuracy to ensure compatibility in recording and reproduction without performing closed-loop control. .

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings.

FIG. 1 shows the configuration of a floppy disk drive system as an embodiment of the present invention.
is a media cassette made of plastic etc., which stores a flexible magnetic disk inside.

A hub (not shown) exposed on the lower surface of the media cassette is provided at the center of the disk (not shown), and the magnetic disk is rotated by engaging the drive pin 4B of the spindle 4 with the drive hole of the hub. rotational drive is performed.

In this embodiment, the spindle 4 is driven by a step motor l instead of a conventional DC motor or the like. That is, the spindle shaft 4A is directly connected to a large-diameter flywheel 3, and this flywheel 3 is connected via a belt 5 to a small-diameter pulley 2 attached to the rotating shaft of a step motor l. The flywheel 3 and the pulley 2 constitute a speed reduction means, and if the ratio of the diameters of the pulley 2 and the flywheel 3 is K and the rated rotation speed of the spindle 4, that is, the magnetic disk is N [rpsl, then the step motor 1
The required driving rotation speed is 2·N [rp·l.

As is well known, since a step motor is driven by step-like pulses, when the step motor is driven continuously, there are small periodic fluctuations in the rotation speed. Since this small variation in rotational speed (speed) is undesirable in order to maintain compatibility of recording and reproduction, in this embodiment, the flywheel 3 is made of aluminum, steel, or other gui-cast product, and the rotational variation of the step motor l is It is assumed that the inertial mass is sufficient to absorb the inertia.

Further, in this embodiment, in order to further smoothen the rotational characteristics of the step motor 1, the drive control circuit 12 for driving the step motor 1 performs drive control with the characteristics shown in FIG.

The two solid line waveforms 7.9 in FIG. 2 are rectangular wave drive signals by two-phase excitation that are normally used to drive a step motor.

In such a step-like drive waveform, the rotor of the step motor does not move continuously, but is caused by small rotational fluctuations as described above. In order to reduce this small rotational fluctuation, in this embodiment, the drive control circuit 12 is operated by the reference numeral 8. in FIG. The step motor l is driven with a curvilinear waveform approximating a sine wave as shown by the broken line lO. For this reason, the drive control circuit 12 is assumed to have a waveform shaping circuit composed of an integrating circuit or the like at its output stage.

With the above configuration, the rotational characteristics of the step motor 1 are smoothed, and the flywheel 3 having a large inertial mass absorbs small rotational fluctuations of the step motor 1, so that the magnetic disk stored in the media cassette 6 can be The magnetic disk can be rotated with sufficient precision to suppress fine rotational fluctuations of the driven spindle 4 and ensure compatibility in recording and reproduction.

According to the above configuration, by controlling the control signal of the drive control circuit 12 that drives the step motor 1 with high precision using a crystal oscillator or the like, it becomes possible to open-loop control the number of rotations of the magnetic disk. . Therefore, there is no need to provide a rotational speed detection means such as a rotary encoder as in conventional devices, and the configuration of the control system is further simplified, making it possible to significantly reduce the manufacturing cost of the device.

In addition to the above embodiments, the belt 5 connecting the pulley 2 and spindle 3 is made of an elastic material such as rubber, and by taking this elastic coefficient into consideration, fine rotational fluctuations (vibrations) of the step motor l can be prevented. With such a configuration, which may function as a damper that absorbs the magnetic disk, it is possible to further improve the accuracy of the rotational speed of the magnetic disk.

The above configuration is applicable not only to floppy disk devices but also to various magnetic disk devices such as hard disk devices.

[Effects] As is clear from the above description, according to the present invention, in a magnetic disk device that rotates a magnetic disk at a predetermined rotational speed and performs magnetic information recording and reproduction on a Fi1 disk, Since the configuration uses a step motor as the magnetic disk drive means, there is no need for a complicated closed-loop control system using a rotation speed detection means as in conventional devices, and it is possible to prevent fluctuations in the spindle shaft rotational speed due to load fluctuations. It is possible to obtain magnetic disk rotational speed accuracy sufficient to suppress the magnetic disk rotation speed and ensure compatibility in recording and reproduction.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing one embodiment of a magnetic disk device according to the present invention, and FIG. 2 is a diagram showing step motor drive waveforms in the device of FIG. 1...Step motor 2...Pulley 3...Flywheel 4...Spindle 5...Belt
6... Media jacket 12... Drive control circuit 1 Fig. ST, 7 leaf-evening φh7'i by'F! Showed interest Iko 2nd vA

Claims (1)

[Scope of Claims] 1) In a magnetic disk device that rotates a magnetic disk at a predetermined rotational speed and performs recording and reproduction of magnetic information on the magnetic disk, a step motor is used as the magnetic disk drive means. Features of magnetic disk device. 2) A driving member having a large inertial mass sufficient to absorb minute rotational fluctuations of the step motor is provided in the drive system between the magnetic disk and the step motor. Magnetic disk device. 3) The magnetic disk device according to claim 1 or 2, wherein the excitation phase drive current of the step motor is controlled in a curve with a waveform approximating a sine wave.