JPS6350973A - Flexible disk driving device - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a direct drive motor for rotationally driving a flexible magnetic recording medium of a flexible disk drive device.

[Prior Art] A conventional direct drive motor that rotationally drives a flexible magnetic recording medium (hereinafter referred to as a flexible disk) has a structure as shown in FIGS. 5 and 6. A plan sectional view of the drive motor, FIG. 6 is a sectional view of a conventional direct drive motor.

3, each for rotating a flexible disk.
Phase direct drive motor is shown.

In FIG. 6, a rotor magnet 1 is magnetized into eight poles and is connected to a rotating shaft 4 through a rotor yoke 2 and a rotor holder 3.

The rotor holder 3 is provided with a chucking mechanism for fixing and rotationally driving a chucking hub 21 provided on the flexible disk 20. (Not shown.) On the other hand, a circuit board 5 is placed opposite the rotor magnet 1, and the circuit board 5. A drive coil 6 is attached to the drive coil 6 in the positional relationship shown in the plan sectional view of FIG.

In this structure, a magnetic head 22 for recording and reproducing rotor information on the flexible disk 20 moves above the rotor yoke 2 in the direction of arrow 7 in the figure, and performs recording and reproduction on the flexible disk 20.

The drive coil 6 for rotationally driving the rotor magnet 1 is energized by an electronic circuit for detecting the magnetic pole position of the rotor magnet 1 . To ensure that the rotor magnet 1 rotates at a constant speed, the circuit board 5 is provided with a conductive pattern for a frequency generator that generates power using the magnetic flux generated by the rotational speed detection magnet 8 attached to the rotor yoke 2. The frequency of the alternating current signal obtained from this pattern is detected and the current flowing through the drive coil 6 is controlled to keep the rotation of the rotor magnet 7 and the rotor magnet 3 constant.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional technology, the magnetic noise and electrical noise generated from the drive coil affect the magnetic head, which reduces the reliability of recording and reproduction in the flexible disk drive device, and requires methods to prevent these noises. A shield member was required, and a capacitor had to be added to the motor drive circuit to prevent electrical noise from occurring.

In addition, in order to detect the rotational speed of the rotor, since the distance between the rotor magnet 1 and the circuit board 5 is wide, it is necessary to provide a rotation speed detection magnet 8 separate from the rotor magnet 1 to detect changes in the magnetic flux of the rotor magnet 1. It could not be detected and the cost was high.

Therefore, the present invention aims to solve these problems.
The purpose is to provide a spindle motor for a flexible disk drive device that generates less noise and is inexpensive, thereby completely improving the reliability of the flexible disk drive device.

[Means for Solving the Problems] The flexible disk drive device of the present invention has the following features in a direct drive motor for rotating a flexible disk: 1) A drive coil is arranged asymmetrically with respect to the center of rotation of the rotor.

2) Eliminating the drive coil near the magnetic head that records and plays back information on the flexible disk.

3) A rotation detector was installed in the space where the drive coil was removed to detect the rotation speed of the rotor.

It is characterized by the above.

[Effect]

According to the above configuration of the present invention, by removing the drive coil around the magnetic head for recording and reproducing information on a flexible disk, the distance between the magnetic head and the drive coil becomes longer, and the electric current generated from the drive coil is reduced. It is possible to prevent the influence of noise and magnetic noise from reaching the airtight head.

Furthermore, by installing a rotor rotation detector in the space where the drive coil is removed, the degree of freedom in arranging the drive coil increases and motor efficiency can be improved.

[Real example]

FIGS. 1 and 2 show a three-phase direct drive motor for rotating a flexible disk in one embodiment of the present invention. FIG. 1 is a plan cross-sectional view of the direct drive motor of the present invention, and FIG. 1 shows a cross-sectional view of a direct drive motor of the invention.

In FIG. 2, the direct drive motor includes a rotor for rotationally driving the flexible disk 20 by a rotor magnet 31, a rotor yoke 52, a rotor holder 33, and a rotating shaft 34, and includes a drive coil 36, a circuit board 35, rotor magnet 31
A rotational speed detection board 38 having a frequency generating electrode for detecting the rotational speed is disposed facing the rotor magnet 31.

FIG. 1 is a plan view of the configuration shown in FIG. 2 with a part of the rotor removed, showing the drive coil 56.
is arranged asymmetrically with respect to the output @ 34, and the rotational speed detection board 38 is arranged in an open space without the drive coil 36. The rotation speed detection board 38 is provided with a pattern 38A for detecting changes in the magnetic speed of the rotor magnet 31 as changes in current according to Fleming's right-hand rule.

The magnetic head 22 that performs recording and reproduction on the flexible disk 20 moves directly above the rotor yoke 32 in the figure, and its planar arrangement is such that it moves along the arrow 39 in FIG.

In this structure, since the drive coil 36 is not placed near the magnetic head 22 that performs recording and reproduction on the flexible disk 20, the noise generated by the drive coil 36 is not placed in the vicinity of the magnetic head 22, which is sensitive to magnetic noise and electrical noise. It does not affect.

Furthermore, as is clear from a comparison with the cross-sectional view of the conventional direct drive motor shown in FIG. , the rotor magnet 61 can serve both to generate rotational force and to detect rotational speed. In addition, since there is no magnet for rotation detection on the outer periphery of the rotor yoke 32, the drive coil 6
6 can be arranged up to the outer periphery of the rotor magnet 31, the volume of the drive coil 36 can be increased, and the rotation radius that generates the driving force becomes larger, resulting in a larger rotational torque compared to the outer diameter of the rotor. can be obtained, and the energy saving of the spindle motor can be measured.

In this example, the rotor magnet 31 is magnetized with 10 poles, but the number of magnetized poles is further increased to 12 poles,
By using 14 poles, etc., the arrangement of the drive coil 36 increases the degree of freedom, and it is also possible to expand the space for the rotation speed detection board 38 in the M1 diagram. It is also possible to provide several locations during one rotation, with a rotational speed detection board at one location and a Hall element for detecting the position of the rotor magnet 31 at other locations.

3 and 4 show another example of actual winding according to the present invention. FIG. 3 is a cross-sectional view of the direct drive motor of the present invention, and FIG. 4 is a plan cross-sectional view of the direct drive motor of the present invention. shows.

In FIG. 3, the direct drive motor has a rotor magnet 31. Rotor yoke 32, rotating shaft 34
．． The flexible disk 2 is held by the chucking section 41.
The drive coil 36. A stator 429 circuit board 35 is arranged facing the rotor magnet 31.

FIG. 4 is a plan view of the motor with a part of the rotor removed in the configuration shown in FIG.
arranged asymmetrically.

Then, recording and reproduction are performed on the flexible disk 20, and the magnetic head 22 moves to the fourth position in the plane direction of the motor.
Move the arrow 39 in the figure.

In this structure as well, a drive coil 3 is located near the magnetic head 22 that performs recording and reproduction on the flexible disk 20.
6 is not arranged, the noise generated by the drive coil 360 does not affect the magnetic head 22, which is sensitive to magnetic noise and electrical noise.

In addition, in this example, the stator 42 is also connected to the output shaft 3.
4, and the stator near the magnetic head 22 is removed, but by configuring it in this way,
Furthermore, it goes without saying that the influence of the drive coil 36 on the magnetic head 22 is reduced.

〔Effect of the invention〕

As described above, according to the present invention, by removing the drive coil of the direct drive motor from the vicinity of the magnetic head that performs recording and reproduction on the flexible disk,
There is no influence of electrical noise or magnetic noise generated from the drive coil for the magnetic head, and the reliability of recording and reproduction of the flexible disk drive can be significantly improved. In addition, magnetic and electrical shielding can be simplified, and noise removal measures for the drive circuit of the direct drive motor can also be simplified. Furthermore, the speed detector of the direct drive motor, the detection means of the rotor magnet, etc. can be effectively placed in the empty space of the drive coil, eliminating the need for a dedicated rotation speed detection magnet, reducing costs, and It also has the effect of increasing the motor efficiency by spreading the position around the outer circumference of the direct drive motor.

[Brief explanation of the drawing]

1 and 4 are plan sectional views of the direct drive motor of the present invention. FIGS. 2 and 3 are cross-sectional views of the direct drive motor of the present invention. Figure 5 is a plan cross-sectional view of a conventional direct drive motor. Figure 6 is a cross-sectional view of a conventional direct drive motor. 20... Flexible disk 22... Magnetic head 31... Rotor magnet 62... Rotor yoke 33... Rotor holder 64... Output shaft 35... Circuit board 36... Drive coil 38
...Rotation speed detection board 41...Chucking part
42...Stator and above Applicant Seiko Epson Co., Ltd. Figure 3 7 ≦ 20 mm, JP-A-Sho I; 3-50973 (5) Figure 5

Claims (1)

[Scope of Claims] 1) In a flexible disk drive device that has a magnetic head for recording and reproducing, chucks a flexible magnetic recording medium, rotates it with a direct drive motor, and performs recording and reproducing on the magnetic medium. A flexible disk drive device characterized in that the drive coil of the drive motor is arranged asymmetrically with respect to the center of rotation of the rotor. 2) The flexible disk drive device according to claim 1, wherein regarding the arrangement of the drive coils, the drive coils near the magnetic head are removed. 3) The motor according to claim 1 or 2, characterized in that a rotation speed detector for detecting the rotation speed of the direct drive motor is installed in a space from which the drive coil is removed. Flexible disk drive device.