JPS6331459A - Spindle motor - Google Patents

Abstract

PURPOSE:To prevent a spindle motor from being erroneously disposed or operated by forming the motor in an inner rotor type, and arranging an index detecting mechanism on the inner surface of a rotor yoke. CONSTITUTION:A spindle motor for a magnetic disk unit is composed of a shaft 1 having a hub 2 secured to one end thereof, a cuplike rotor yoke 6 secured to the shaft, a ringlike rotor magnet 7 and a stator core 9 on which a stator coil 8 is wound. In this case, the stator core 9 is disposed in a housing 14, and an index magnet 10 is secured to the recess in the inner surface of the yoke 6. A magnetic detector 11, such as a Hall element, is disposed at an air gap from the magnet 10. Thus, the magnet 10 and the detector 11 can be covered with a high-permeabily material to reduce the influence of external noises.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a structure of a spindle motor, and more particularly to a structure for detecting a υ index signal by a spindle motor.

[Conventional technology]

As shown in FIG. 5, the structure of a conventional spindle motor is such that a hub 2 is fixed to one end of a shaft 1, and a plurality of magnetic disks 3 are attached to the hub 2 by a disk clamp plate 5 via a disk spacer 4. A cup-shaped rotor yoke 51 is fixed to the other end of the shaft 1, a ring-shaped rotor magnet 52 is fixed to the inner surface, and a stator coil 5 is mounted on the same circumferential side of the rotor magnet 52 with a gap in between.
The stator core 54 to which the magnetic disk 3 is wound is disposed, and the stator core 54 is disposed in the housing 14, and the bearing 12 that supports the shaft 1 and the seat A/13 that prevents dust from entering the magnetic disk 3 side are also disposed in the housing 14. 14, an index magnet 55 is fixed to the outer peripheral side 1 of the rotor yoke 51, and a magnetic detection element 56 arranged at a predetermined position of the housing 14 detects the index magnet 55.
9 and an index signal is obtained, the housing 14 is fixed to the pace frame 15, the inside of the base frame 15 is sealed with a cover 16, and a circuit board 17 on which the circuit components of the magnetic disk drive are mounted is mounted below the spindle motor. will be placed. When the spindle motor rotates, the index magnet 55 also rotates at the same time, and the magnetic detection element 56 obtains an index signal at a predetermined position during one rotation.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional technology, the index magnet and magnetic detection element are not magnetically cooled, and magnetic noise from outside the magnetic disk drive may cause an error in the position where the index signal is generated. The generated switching noise causes the magnetic detection element to malfunction, causing the magnetic disk drive to malfunction.
The reliability of the device was significantly reduced.

The present invention is intended to solve these problems, and its purpose is to improve the reliability of magnetic disk drives by enabling an index signal generation mechanism that is less susceptible to noise. One Means for Solving the Problems] A spindle motor of the present invention is a spindle motor that rotates a magnetic dinuque, in which a rotor magnet is arranged on the inner circumferential side of a stator core around which a stator coil is wound, with a gap in between. The rotor magnet has an inner circumferential side fixed to the outer circumferential side of a cup-shaped rotor yoke, an index magnet and a magnetic detection element are arranged on the inner side of the rotor yoke, and the index magnet is fixed to the inner side of the rotor yoke. do.

[Effect]

According to the above configuration of the present invention, the mechanism for generating the index signal can be disposed on the inner surface of the rotor yoke, and the rotor yoke can be separated from the stator coil.

〔Example〕

FIG. 1 is a cross-sectional view of a main part of a spindle motor of a magnetic disk device according to an embodiment of the present invention, in which a bald 2 is fixed to one end of a shaft 1, and a plurality of magnetic disks 3 are connected to the disks via a disk spacer 4. It is attached to the hub 2 by a clamp plate 5, a cup-shaped rotor yoke 6 is fixed to the other end of the shaft 1, and a ring-shaped rotor magnet 7 is fixed to the outer surface side. The stator core 9 is disposed in a housing 14, and an index magnet 10 is fixed to an inner recessed part of a cup-shaped rotor yoke 6. A magnetic detection element 11 such as an L/element or a Hall IC is arranged at a predetermined position in a housing 14, and the shaft 1 is rotatably supported by a bearing 12 arranged in the housing 14, and a dustproof seal is installed at a seat/L/B. The housing 14 is fixed to a base frame 15, the inside of the pace frame 15 is sealed with a cover 16, and a circuit board 17 on which circuit components of the FFL disk drive are mounted is disposed below the spindle motor. Similarly, the rotor magnet 7 is a magnet that is magnetized into multiple poles in the radial direction, and is a ring-shaped magnet that is magnetized in sections or a ring-shaped structure using multiple bow-shaped magnets. 10 is a magnetic detection element 1
1, the index magnet 10 and the magnetic detection element 11 may be arranged so that they are aligned in the axial direction.

FIG. 2 is a sectional view of a main part of an index signal detection part in an embodiment of the spindle motor as shown in FIG. 10 is fixed, and a magnetic detection element 11 such as a Hall element is arranged opposite to the index magnet 10.
The magnetic detection element 11 has a lead 21 electrically connected to the motor board 25 via a solder portion 22, and sends an index signal to the control circuit.

FIG. 3 is a sectional view of the main part of the index signal detection section in another embodiment of the spindle motor as shown in FIG.
is fixed to the scoop 31, the leap 31 is arranged on the opposite side of the magnetic detection element 11 with respect to the index magnet 10, and the sleeve 31 is made of a material with high magnetic permeability such as iron. The magnetic flux density due to the index magnet (which passes through the index magnet 11) 10 increases and the S/N improves.0 FIG. , the cup-shaped rotor yoke 6 has a recess on the lower side of the spindle motor, and an index magnet 10 is fixed to a predetermined position on the inner surface of the recess, and the magnetic detection element 11 is similar to the position detection element of the rotor magnet 7. The motor board 41 is arranged on a motor cover 42 made of a steel plate or the like, the motor cover 42 is fixed to the stator core 9 or the housing 14, and the magnetic detection element 11 is arranged on the rotor yoke 6 or the motor cover 42. yoυ
Shielded from external noise.

As seen in the above embodiments, the index magnet 10 and the atmospheric detection element 11 can be covered with a material with high magnetic permeability, which can reduce the influence of external noise, which is the main source of noise. It is shielded from the stator coil/I/8 and the circuit board 17, and the index signal can be detected correctly even against noise from outside the magnetic disk device.

The index signal is used to know the circumferential position of the magnetic disk, and also to determine the rotational speed of the magnetic disk by observing the rotation period of the index signal, and one index signal is generated every time the magnetic disk goes around. However, obtaining index signals multiple times per cycle is easily possible by increasing the number of index magnets, magnetizing multiple poles, or increasing the number of magnetic detection elements.

〔Effect of the invention〕

As described above, according to the present invention, position errors and malfunctions of index signals can be prevented by using an inner rotor type spindle motor of a magnetic disk drive and arranging an index detection mechanism on the inner surface of the rotor yoke. Accordingly, it is possible to obtain a spindle motor for a magnetic disk drive having a simple, highly reliable index signal generation 'IR' structure.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of a spindle motor of a magnetic disk device according to an embodiment of the present invention. FIG. 2 is a sectional view of a main part of an index signal detection section of a spindle motor in an embodiment of the present invention. FIG. 3 is a sectional view of a main part of an index signal detection section of a spindle motor in another embodiment of the present invention. FIG. 4 shows the main part I of the index signal detection section of the spindle motor in still another embodiment of the present invention! JT surface diagram. FIG. 5 is a sectional view of a main part of a spindle motor of a conventional magnetic disk device. 5...Magnetic disk 6...Rotor yoke 7--Rotor magnet 8--Stator coil y? --- Stator core 10 --- Index magnet 11 ---
Magnetic detection element or more 3゛? Nischita coil Fig. 1 Fig. 3 Fig. 4

Claims (1)

[Claims] In a spindle motor that rotates a magnetic disk, a rotor magnet is disposed on the inner circumferential side of a stator core around which a stator coil is wound with a gap in between, and the inner circumferential side of the rotor magnet is fixed to the outer circumferential side of a cup-shaped rotor yoke. and at least one on the inner side of the rotor yoke.
What is claimed is: 1. A spindle motor comprising: index magnets and at least one magnetic detection element, the index magnet being fixed to an inner surface of the rotor yoke.