JPH0640457Y2 - Spindle motor rotor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial field of application) The present invention relates to a rotor of a spindle motor used for driving a magneto-optical disk, an improvement of a turntable for chucking a medium, and a spindle. The present invention relates to improvement of characteristics of the motor itself.

(Problems to be Solved by Conventional Techniques and Inventions) Conventionally, as a spindle motor for driving a magneto-optical disk, one shown in FIG. 1 is known. That is, a shaft 3 is rotatably attached to the center of a stator base 1 through bearings 2 and 2, a turntable 4 made of brass or aluminum is fixed to the shaft 3, and a field is passed through a return path plate 5 through a return path plate 5. Magnet 6
Is fixed to form a rotor, and a stator coil 7 facing the field magnet 6 is fixed to the stator base via a yoke 8. An attraction magnet 9 is arranged on the upper surface of the turntable 4 for chucking a medium such as a magneto-optical disk. In the figure, 10 is an FG pattern and a coil wiring substrate.

However, in such a configuration, the attraction magnet 9
Is required, and the number of parts increases, which is disadvantageous in terms of cost.

Further, it is conceivable to delete the attraction magnet 9 and use the leakage magnetic flux of the field magnet, but since there is the return path plate 5, the leakage magnetic flux becomes small even with the recent Nd magnet, and the clamping force is increased. Is weak and not practical.

Further, as disclosed in Japanese Patent Application Laid-Open No. 63-195856, a turntable device formed of a plastic magnet has been proposed, but it is unclear what structure the spindle motor will have.

This invention intends to solve the above problems with a simple configuration.

(Means for Solving the Problem) As a means for chucking a medium on a turntable, the present invention relates to a rotor of a spindle motor in which the turntable itself is formed of a plastic magnet, and a field magnet is attached to the turntable. It is characterized in that the turntable is directly arranged on the outer circumference of the magnet so that a part of the turntable is placed, and a reverse magnetic field is formed on the outer circumference so as to correct the magnetization curve of the field magnet.

(Function) When the turntable itself is made of a plastic magnet in this way, the medium can be securely chucked without increasing the number of parts, and the turntable itself can also serve as the return path plate of the field magnet. The partial reverse magnetic field has a function of correcting the magnetization curve of the field magnet.

[Embodiment] An embodiment of the present invention is a turntable as shown in FIG.
44 is a rare earth element or is a ferrite plastic magnet, the return path plate is removed to reduce the number of parts, and the field magnet 6 is directly fixed.

This is advantageous in terms of cost, and by matching the poles of the field magnet 6, it is possible to also serve as a return path plate that functions to increase the amount of magnetic flux of this field magnet. When the return path plate is also used as the return path plate, in order to make the trapezoidal magnetization curve act like a sine curve at each pole of the field magnet,
As shown in FIG. 4 and FIG. 4, a part of the turntable is placed on the outer peripheral part of the field magnet 6, and in order to correct the magnetization curve of the field magnet 6, an inverse magnetic field is applied to a part of each pole. The parts 44a and 44b of the turntable 44 are magnetized so as to be turned on.

In the figure, other configurations are the same as those in the above-mentioned conventional FIG. 1, and therefore, the same reference numerals are given and the description thereof is omitted.

[Advantages of the Invention] This invention is advantageous in terms of cost because the number of parts can be reduced as described above, and moreover, it can be improved in characteristics and is extremely useful in practice.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a conventional spindle motor for driving a magneto-optical disk, FIG. 2 is a sectional view of the same part of the present invention, FIG. 3 is a partial plan view showing a magnetized state of FIG. 2, and FIG. 4 is a partial cross-sectional view showing the magnetized state of FIG. 44 is a turntable 44a is a reverse magnetic field part 6 is a field magnet

Claims (1)

[Scope of utility model registration request] 1. In a rotor of a spindle motor in which a turntable itself is formed of a plastic magnet as means for chucking a medium on the turntable, a field magnet is provided on the turntable, and a field magnet is provided on the outer circumference of the field magnet. A rotor for a spindle motor, which is placed directly so that a part of it is placed, and an opposite magnetic field is formed on this outer peripheral portion so as to correct the magnetization curve of the field magnet.