JPH09285091A - Thin flat coreless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a space in the axial direction of a thin flat coreless motor to reduce the thickness of the motor, simplify a whole assembly process and, further, reduce a power consumption to improve the life of the motor for a portable application. SOLUTION: A shaft 15 is stood on a plate 14, field magnets 16 are provided around the shaft 15 so as to have their N-poles and S-poles arranged alternately and brushes 17 fixed to a brush plate are provided in gaps between the field magnets 16 to constitute a stator unit 25. Rotor coils 19 are arranged in a circle so as to face the field magnets 16 on the lower surface of a turntable 18 on which a recording medium is mounted, a bearing unit 20 which is coupled with the shaft 15 is provided at the center of the lower surface of the turntable 18, commutator segments 21 which are brought into slide contacts with the brushes 17 in the lower part and a recording medium clamping means 22 is on the upper surface of the turntable 18 to constitute an armature rotor unit 24. The armature rotor unit 24 is rotatably attached to the stator shaft 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an information medium, such as a magnetic recording medium such as a floppy disk (FD), an optical recording medium such as a compact disk (CD), or a magneto-optical medium such as a mini disk (MD). It is used for driving a disk such as a device that rotates a recording medium to record information on the recording medium or reproduces the information recorded on the recording medium, and especially for portable use where a thin motor is required. The present invention relates to an information reproducing device.

[0002]

2. Description of the Related Art Conventionally, motors used in these devices have a structure as shown in FIGS. This type of motor has a structure in which the bearing portion includes a shaft and a bearing for receiving the shaft in order to obtain a rotating function. As the performance required for the motor, surface runout, that is, joining accuracy of the turntable to the shaft and suppression of runout of the shaft itself are often required. Further, in the CD and MD motors, it is required to improve the vertical accuracy of the shaft with respect to the motor mounting parts. In order to deal with these precisions, there are a conventional brushless motor as shown in FIG. 2 and a conventional iron core type motor as shown in FIG.

In the conventional brushless motor shown in FIG. 2, a shaft 2 is rotatably inserted into a stator portion 1 in which a coil is wound around an iron core. A ring-shaped magnet 4 is arranged on the outer circumference of the rotor portion 3, and a turntable 6 on which a recording medium clamping magnet 5 is arranged is arranged above the rotor portion 3 and is rotatably supported via bearings 7 and 7 '. In such a motor, it is necessary to regulate the shaft runout of the shaft 2 in order to suppress surface runout. As a measure for controlling this shaft runout, in order to reduce runout of the shaft 2 during rotation, the bearing of the shaft 2 is set to 2
I had to set one.

On the other hand, in the conventional iron core type motor shown in FIG. 3, a commutator 9 is attached to a lower portion of a rotor portion 8 formed of a laminated core around which a coil is wound, and a central shaft 10 is provided with two bearings 11 and 11 '. Is rotatably supported by a turntable 12 mounted on the top thereof. The brush 13 is fixed to the substrate under the rotor portion 8 so as to be capable of sliding contact with the commutator 9. In the motor of FIG. 3, it is necessary to provide two bearings at a distance in order to regulate the shaft runout shown in FIG.

[0005]

In the brushless motor of FIG. 2, it is necessary to increase the axial length of the two bearings 7 and 7'as described above, and as is apparent from FIG. Requires a large space in the axial direction of the shaft. Further, there is a drawback that cogging occurs and a driving circuit is further required, resulting in a large power consumption.

Similarly, in the conventional iron core type motor shown in FIG. 3, it is necessary to arrange the two bearings 11 and 11 'at a distance from each other. Therefore, it is necessary to take a large space in the axial direction of the shaft 10. . In addition, since the rotor is supported by the upper and lower bearings, the vertical accuracy of the shaft is difficult to obtain, and a space between the rotor and the housing case, a space between the rotor and the plate, and a space between the housing and the turntable are required. It is difficult to reduce the thickness.

Further, in order to press-fit or bond the turntable to the shaft after completion of the motor,
Since the surface runout accuracy is difficult to obtain, and the shaft exists between the rotor that is the rotation torque generating unit and the turntable that is the recording medium mounting unit, there is a possibility that problems such as idling and torsional resonance of the shaft may occur. In addition, there is a drawback that cogging occurs like the brushless motor. As described above, in any of the conventional motors, it is necessary to secure a large axial space of the bearing portion, so that the space below the turntable occupies a large space, which hinders the reduction of the thickness of the motor itself. .

Therefore, the present invention has been made to solve the above problems, and provides a motor that can be made thinner by reducing the axial space of the motor and can be stably rotated. The purpose is to do.

[0009]

According to the present invention, as shown in FIG. 4, a shaft 15 is erected on a plate 14 and a field magnet 16 is provided around the shaft 15 so that N and S poles are alternately arranged in a circumferential shape. Place and
The rotor coil 19 is arranged in a circular shape on the lower surface of the turntable 18 on which the recording medium is placed, facing the field magnet 16 and the stator portion 25 in which the brush 17 fixed to the brush stand is arranged in the gap, Further, a bearing 20 engaging with the shaft and a commutator piece 21 so as to be slidably contactable with a brush are arranged in the center of the bearing 20. This is achieved by using the armature rotor part 24 having the yoke 23 installed therein and rotatably mounting the armature rotor part 24 on the shaft 15 of the stator part.

Comparing the verticality of the shaft with that of the conventional example, in the brushless motor, there are five factors, namely, the squareness of the bearing press-fitting portion of the mounting part, its inner diameter, the bearing outer diameter, the bearing inner diameter, and the press-fitting accuracy. On the other hand, the present invention is advantageous in improving accuracy because it requires only four factors, namely, the squareness of the shaft press-fitting portion of the mounting component, its inner diameter, the shaft outer diameter, and the press-fitting accuracy. Also, when comparing the accuracy of the bearing and the shaft, it is clear that the latter is more accurate than the former due to the difference in the method.

In the present invention, a coil is arranged below the turntable and functions as a motor rotor,
A magnet portion facing the coil is arranged on the plate so as to face it, and functions as a stator. In the present invention, the information recording medium mounting portion is provided as the rotor portion. Only one oil-impregnated metal is used for the bearing, and an oil reservoir groove is formed on the shaft.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Note that the embodiments described below are
Since it is a preferred specific example of the present invention, various technically preferable limitations are attached, but the scope of the present invention is, unless otherwise stated to limit the present invention, in the following description.
It is not limited to these embodiments.

FIG. 1 shows a preferred embodiment of the motor of the present invention, in particular a face-to-face type coreless motor. In the face-to-face type motor shown in FIG. 1, a motor shaft 15 is erected on a plate 14 as a stator portion, and a fan-shaped rare earth magnet 16 for field magnets is arranged around the motor shaft 15 in an alternating circumferential pattern. Six poles are arranged to form a stator portion 25, and a brush 17 fixed to a brush base is arranged in a pair of gaps between the stator portions 25. Further, as the armature rotor section 24, a rotor coil 19 using a coil having a wire diameter of φ0.11 mm is arranged in a circular shape on the lower surface of the turntable 18 on which a recording medium is mounted, and the motor is provided at the center. A bearing 20 that engages with the shaft, a commutator 21 is further arranged at the tip thereof, and a rare earth bond magnet 22 for recording medium clamp is installed on the upper surface.
A back yoke 23 is arranged on this lower surface to form a magnetic circuit in the rotor coil.

As a result of confirming the performance as this motor,
Compared with the conventional motor, the thickness as a flat motor is
In contrast to the conventional size of 8 to 9 mm, the present invention is thinned to 6.5 mm, and due to the reduction of the power consumption of the circuit part, the life of the portable device is about 1.3 times as long as that of the conventional product.

[0015]

The motor can be made thinner by integrally forming a turntable on which a recording medium is placed and a bearing, and incorporating a coil therein to form an armature rotor as a whole. By vertically fixing the shaft on the plate, the squareness of the shaft is determined only by the press fitting accuracy. Further, since the turntable is formed with the bearing inner diameter as a boundary, the runout accuracy of the disk is determined by the forming accuracy and the clearance between the shaft and the bearing. Power consumption can be reduced by using a brush motor. Since the assembling is completed by dropping the armature rotor onto the shaft of the stator, the assembling process can be simplified. According to the above configuration, it is possible to reduce the space in the direction related to the rotating shaft of the motor. Moreover, the posture of the rotor portion during rotation can be stabilized.

[0016]

According to the present invention, in the brushless motor, in addition to the rated current of 20 to 30 mA, and the consumption current of the circuit is required, the rated current could be suppressed to 20 to 30 mA by using a commutator. In addition, there is no cogging of rotation, the cost of parts can be reduced by the number of circuit parts required for the brushless motor, and the thickness of the motor is 6.5 mm, so it can be made thinner, and there is only one space, which facilitates dimensional control. Further, the total assembling process is greatly simplified to one process in which the armature rotor is simply dropped onto the shaft of the stator section.

[Brief description of drawings]

FIG. 1 is an assembled perspective view of a flat coreless motor of the present invention.

FIG. 2 is a half sectional view of a conventional brushless motor

FIG. 3 is a sectional view of a conventional iron core type motor.

FIG. 4 is a sectional view of the flat coreless motor of the present invention.

[Explanation of symbols]

 1 stator 2 motor shaft 3 rotor 4 ring magnet 5 clamp magnet 6 turntable 7 bearing 7'bearing 8 rotor 9 commutator 10 motor shaft 11 bearing 11 'bearing 12 turntable 13 brush 14 plate 15 motor shaft 16 field Magnetic magnet 17 Brush 18 Turntable 19 Rotor coil 20 Bearing 21 Commutator 22 Clamp magnet 23 Back yoke 24 Rotor part 25 Stator part

Claims (1)

[Claims] 1. A stator in which a shaft is erected on a plate, field magnets are circumferentially arranged alternately around the shaft, and brushes fixed to a brush stand are arranged in the gap. Section, a rotor coil is arranged in a circular shape on the lower surface of a turntable on which a recording medium is mounted, facing the field magnet, and a bearing portion engaging with the shaft is provided at the center, and further below the bearing portion. A commutator piece is arranged so that it can be slidably contacted with the brush, and an armature rotor section having a recording medium clamp means installed on the upper surface of the turntable, and the armature rotor section is rotatably mounted on the stator section shaft. A thin flat coreless motor.