JPS60207737A - Spindle motor used in common for magnetic chuck - Google Patents

Abstract

PURPOSE:To make a motor into flat form and reduce the number of parts by forming a chuck plate integrally onto the edge surface of the housing of a permanent-magnet shaped rotor and accommodating the edge part of the permanent magnet into the housing and using a chuck circuit in common. CONSTITUTION:A motor magnetic circuit is constituted of a rotor magnet 6 inside a motor, and a magnetic circuit is constituted between a chuck magnet part 6a and an installed article on the upper surface side of a rotor housing 2, namely on a seat standard surface 2a side. The motor is fixed onto the inner bottom surface of a housing 10, and when the disc hub 12 of a magnetic disc 11 is brought into contact with the seat standard surface 2a, the chuck magnet part 6a attracts the disc hub 12 and holds it rotatably in the state where the center part is positioned onto a seat standard shaft 3b. Since the chuck magnetic circuit and the magnetic circuit for the revolution of the motor are constituted of only the rotor magnet of the motor, the whole can be made thin and the number of parts can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a spindle motor that also serves as a magnetic chuck.

(Prior Art) Magnetic disk cartridges are attracting attention as a compact, high-capacity recording medium that can replace conventional mini-floppy disks. Therefore, if the configuration of the device itself for driving this cartridge has the same dimensions as the floppy disk driver, compatibility with the floppy disk can be expected.

For this purpose, it is necessary to flatten the drive device, that is, to reduce the thickness of the spindle motor, which is the main reason for increasing the thickness of the device.

Incidentally, a magnetic disk cartridge includes a magnetic disk within a case and a disk hub that also serves as a yoke to which the center of rotation of the magnetic disk is fixed.

In conventional devices, when a cartridge is loaded into the driver device, the case lowers and the bottom surface of the disk hub is attracted to the magnetic chuck, holding the disk hub and magnetic disk in a floating state within the case, and the bottom surface of the magnetic chuck is held. It is designed to rotate at high speed by the rotation of a spindle motor provided.

However, with this structure in which the spindle motor and magnetic chuck are stacked, even if the thickness of other parts of the device is made as thin as possible, the overall shape of the device is ultimately formed based on the thickness of this part. Because of this, there were difficulties in making it thinner.

(Objective of the Invention) An object of the present invention is to flatten the motor and reduce the number of parts by making the spindle motor also serve as a magnetic chuck.

(Structure of the Invention) In order to achieve the above object, the present invention integrally forms a chuck plate on the rotor housing end face of a permanent magnet type rotor, and also forms a chuck plate on the end of the permanent magnets constituting the magnetic circuit of the motor. It is characterized in that it is housed in the rotor housing in a state where it is exposed to the seating reference surface of the rotor housing, and is also used as a magnetic circuit for the chuck.

(Embodiment) FIG. 1 shows a case where the present invention is applied to an outer rotor type brushless DC motor.

In the figure, the motor consists of a stator housing 1 and a rotor housing 2 attached to the outer circumference of the upper surface of the stator housing 1.

The stator housing 1 includes a mounting flange 1a and a cylindrical portion 1b projecting from the center thereof.

and a souter coil 5 are fixed concentrically.

The upper surface of the rotor housing 2 also serves as a chuck plate, and a seating reference surface 2a is formed on the periphery of the rotor housing 2 so as to protrude one step further.

Furthermore, four motor magnets 6 are fixed close to each other in the circumferential direction on the inner peripheral portion of the rotor housing 2 (one of them is omitted in the figure).

At the top of each magnet 6 is a chuck magnet part 6a.
is integrally formed in a protruding manner, passing through a through hole 2b formed in the seating reference surface 2a, and exposing its end portion to the surface of the seating reference surface 2a.

The center of the rotor housing 2 is connected to the spindle 3.
A seating reference shaft 3b integrated with the spindle 3 is attached to the surface of the flange 3a formed on the upper part of the flange 3a through screws B.
It is assembled into one motor with the protruding state.

In addition, what is shown by the code|symbol 7 in the figure is a magnetic sensing element which detects the magnetic pole position of each magnet 6.

Therefore, the motor has a rotor magnet 6 inside it.
A magnetic circuit for the motor is constructed by the chuck magnet portion 6a on the upper surface of the rotor housing 2, that is, on the seating reference surface 2a side, and a magnetic circuit is constructed between the chuck magnet portion 6a and the object to be attached. Note that the upper surface of the magnet portion 6a is the seating reference surface 2.
It is set at a slightly lower position than a.

FIG. 2 shows a state in which the jack motor configured as described above is assembled into a housing of a cartridge type magnetic disk drive.

The motor is fixed to the inner bottom surface of the housing 10,
The disk hub 12 of the magnetic disk 11 is placed on the seating reference surface 28
When brought into contact with each other, the chuck magnet 6a attracts it and rotatably holds it with its center positioned on the seating reference shaft 3b.

In the embodiment, a case where the present invention is applied to an outer rotor type brushless DC motor is shown, but it can also be applied to other types, such as an inner rotor type motor or a flat motor.

Furthermore, the present invention is of course not limited to drive devices for magnetic disk devices, but is also suitable for other devices that require thinning.

(Effects of the invention) In this invention, the magnetic circuit for the chuck and the magnetic circuit for rotating the motor are composed only of the rotary net of the motor. It can be made thinner and has fewer parts, making it cheaper.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional exploded perspective view showing an example of a magnetic chuck motor according to the present invention, and FIG. 2 is a sectional view of essential parts when the same motor is applied to a drive device for a magnetic disk cartridge. 2...Rotor housing 2a...Seating reference surface 6...Rotor magnet 6a...Chuck magnet section and above Applicant: Seiko Seiki Co., Ltd. No. 1N

Claims (1)

[Claims] (1) A chuck plate is integrally formed on the end face of the rotor housing of a permanent magnet type rotor, and the end of the permanent magnet that constitutes the magnetic circuit of the motor is exposed to the seating reference surface of the chuck plate and placed inside the rotor housing. A spindle motor that can be used both as a magnetic chuck and as a magnetic circuit for the chuck.