JP3118053B2 - DC motor with frequency generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC motor, and more particularly, to a DC motor having a frequency generator.

[0002]

2. Description of the Related Art FIG. 5 shows a conventional example of a DC motor having a frequency generator. In the figure, reference numeral 2 denotes a bracket made of aluminum or the like, on which a stator 4 is fixed. The stator 4 has a stator core 6 formed by stacking core plates and an armature coil 8 wound on the stator core 6. The bracket 2 has a bearing 10 and a bearing 10 in a through hole 12 provided in the center.
A shaft 14 is rotatably supported via 13.

[0003] A hub 16 made of a non-magnetic material such as aluminum is fixed to the shaft 14.
The rotor magnet 20 is fixed to face the stator 4 via the pin 8.

[0006] A clamp magnet 22 is provided on the hub 16, and an optical disk 24 is attracted and fixed onto the clamp magnet 22. A back yoke 26 is provided between the clamp magnet 22 and the hub 16 in order to secure a suction force.

At the lower end of the yoke 18, a magnet (FG magnet) 28 of a frequency generator (FG) for controlling the rotation of the motor is fixed. This FG magnet 28
Is formed in an annular shape. This FG magnet 28
A printed circuit board 30 is provided below the FG. The FG magnet 28 is provided on the printed circuit board 30 so as to face the FG magnet 28.
A pattern 32 is provided. This FG magnet 2
8 and the FG pattern 32 is, for example, 0.1
mm.

[0006] The bracket 2 is provided with a Hall element 34 for detecting the magnetic pole of the rotor magnet 20.

[0007]

In the above-described motor, the lead wire 36 from the armature coil 8 is connected to a circuit outside the motor, so that the lead wire 36 is soldered to a wiring pattern on the printed circuit board 30. I have. However, the gap between the FG magnet 28 and the FG pattern 32 is narrow, and if the lead wire 36 is to be led out of the motor through this gap, the lead wire 36 and the FG magnet 28 may come into contact with each other. 36
The FG pattern 32 is affected by a magnetic field generated by a current passing through the FG pattern 32. Therefore, the lead wires 36 are soldered to the lands 48 on the printed circuit board 30 inside the motor.

However, since the space inside the motor is narrow, it is difficult to perform soldering. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a DC motor having a frequency generator capable of connecting a lead wire and a printed board outside the motor.

[0009]

A DC motor having a frequency generator according to the present invention comprises a bracket, a stator having an armature coil fixed to the bracket, and a rotating shaft rotatably provided with respect to the bracket. And a rotor magnet rotatable with the rotating shaft, an FG magnet for a frequency generator rotatable with the rotating shaft, and a printed board provided on the bracket. In a direct current motor provided with a sawtooth-shaped detection pattern arranged in a substantially circular shape facing an FG magnet, a detour is provided by detouring a part of the detection pattern on the printed board, and a printed board in the detour is provided. Is cut out in a U-shape to form a notch piece, and a lead wire from the amateur coil is inserted into the notch piece so that the notch piece and the bra Wherein the throughout the Tsu bets were led to the outside of the motor.

[0010]

According to the present invention, a part of the FG pattern on the printed circuit board is bypassed, and the printed circuit board is partially cut out to provide cutout pieces.

[0011] The lead wire of the amateur coil is inserted into the cutout and led out. Therefore, the lead wire can be led out of the motor without passing through the gap between the printed board and the FG magnet. In addition, the effect of the magnetic field generated by the current passing through the coil wire is
It does not give to the G pattern.

The lead wire led out of the motor is soldered to a printed circuit board.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A DC motor according to the present invention will be described below with reference to the drawings. FIG. 1 is a front sectional view of an embodiment in which the present invention is applied to a brushless motor for an optical disk.

In FIG. 1, reference numeral 2 denotes a bracket made of aluminum or the like, on which a stator 4 is fixed. The stator 4 has a stator core 6 formed by stacking core plates and an armature coil 8 wound on the stator core 6. Also, bracket 2
Are provided in bearings 10 and 13 in through holes 12 provided in the center.
The shaft 14 is rotatably supported via the.

A substantially disk-shaped hub 16A made of a magnetic material such as SUS is fixed to the shaft 14, and an annular side wall 16B made of a material having excellent workability such as aluminum is fixed to the hub 16A. . On the side wall 16B, a rotor magnet 20 magnetized to a predetermined number of magnetic poles via a yoke 18 is arranged and fixed in an annular shape facing the stator 4. The lower end of the yoke 18 has the rotor magnet 2.
It is shortened so as to be higher than the lower end of 0.

The side wall 16B, the yoke 18, the rotor magnet 20, and the FG magnet 28 form a motor side wall 29. A clamp magnet 22 is provided on the hub 16A, and the optical disk 24 is attracted and fixed onto the clamp magnet 22.

Since the side wall 16B is formed of a material having excellent workability, it is easy to adjust the horizontal accuracy of the optical disk 24 by processing the reference surface 38 of the side wall 16B that comes into contact with the optical disk 24.

At the lower end of the rotor magnet 20, a magnet 28 of a frequency generator (FG) for controlling the rotation of the motor is provided.
(FG magnet) is fixed. The FG magnet 28 is formed in an annular shape, and is magnetized so that N poles and S poles are alternately arranged in the circumferential direction. A printed circuit board 30 is provided below the FG magnet 28.

Reference numeral 34 denotes a Hall element for detecting the rotational position of the rotor magnet 20, which is mounted on the printed circuit board 30. FIG. 2 is a plan view showing the printed circuit board 30. FG magnet 28 on printed circuit board 30
The FG magnet 28 having the sawtooth-shaped FG pattern 32 provided in a substantially circular shape corresponding to the position
The gap between 0 is narrow, for example, 0.1 mm to 0.2 mm.

As shown, a part of the FG pattern 32 is detoured toward the center of the motor to form a detour 44 of the FG pattern 32. The printed circuit board 30 is cut out in a U-shape in the detour 44 to form a notch 46, and the lead wire 36 from the armature coil 8 is inserted under the notch 46 so that the notch 46 and the bracket 2 and led out of the side wall 29 of the motor, and soldered to the printed circuit board 30 at the land 48.

By inserting the lead wire 36 into the notch 46 in this manner, the lead wire 36 is soldered to the printed circuit board 30 outside the motor while the gap between the FG magnet 28 and the printed circuit board 30 is kept small. It became possible to attach. In addition, the FG pattern 32 is not affected by the magnetic field generated by the current passing through the lead wire 36.

In the example shown in FIG.
FG pattern 32 is detoured by only one location to form a detour 44
Is provided, and three notches 46 are provided in the detour. However, three detours are provided by detouring three places of the FG pattern 32, and each detour is provided on the FG printed circuit board 30. Notches 46 for the lead wires 36 may be provided one by one in the detour. (See FIG. 3. In this figure, two detours 44a and 44b and two notches 46a and 46b are shown.
Only is shown. ) When the gap (gap) between the FG magnet 28 and the FG pattern 32 is not uniform due to the floating or warpage of the printed circuit board, the FG output increases in a small gap portion, and the FG output decreases in a large gap portion. Thus, the FG output varies. When such a non-uniform printed circuit board is used, for example, if the detour path 44 is provided in a portion having a small gap, the FG output becomes further non-uniform, which causes a problem. With the configuration as shown in FIG. 3, variation in the FG output is reduced.

In this embodiment, since the side wall 16B is made of a magnetic material, it is not necessary to provide a conventional back yoke, and the optical disk 24 can be reliably attracted and fixed only by the clamp magnet 22 provided on the hub 16A. Can be. Therefore, the dimension in the thrust direction (rotational axis direction) can be reduced, and it is possible to cope with a reduction in the thickness of the device.

When the lower end of the yoke 18 protrudes below the lower end of the rotor magnet 20 as in the conventional example, as shown in FIG.
A lot of leakage magnetic flux is generated from the lower end of the. When this leakage magnetic flux is transmitted to the FG pattern, the output of the FG generator becomes uneven. Therefore, in the conventional example, it is necessary to separate the rotor magnet 20 from the printed circuit board 30 and further separate the rotor magnet 20 from the FG magnet 28 as shown in FIG. Therefore, the Hall element 34 facing the rotor magnet 20 also needs to be provided separately from the printed circuit board 30.

In the present embodiment, the yoke 18 of the rotor is shortened so that the lower end of the yoke 18 is located above the lower end of the rotor magnet 20 so that the FG magnet 28
Is fixed to the rotor magnet 20, the following effects can be obtained.

As shown in FIG. 4B, since the leakage flux from the lower end of the rotor magnet 20 is reduced, the distance between the rotor magnet 20 and the printed circuit board 30 can be reduced, and the rotor magnet 20 can be moved downward. Can be provided. For this reason, the Hall element 34 can be provided below in comparison with the related art, and can be provided on the printed circuit board 30 as in the present embodiment.

Although the present invention has been described based on the embodiment shown in the drawings, the present invention is not limited to this embodiment.
Various modifications can be made within the scope described in the claims. For example, although the U-shaped notch 46 is shown, any shape may be used as long as the lead wire 36 can be inserted therethrough.

[0028]

According to the present invention, a part of the FG pattern on the substrate is bypassed, and the substrate is partially cut to form a notch, and the lead wire of the amateur coil is inserted into the notch. Through the notch and the bracket,
The connection between the lead wires and the printed circuit board can be made outside the motor.

[Brief description of the drawings]

FIG. 1 is a front sectional view of an embodiment of a DC motor having a frequency generator according to the present invention.

FIG. 2 is a view showing an FG pattern substrate of the embodiment shown in FIG.

FIG. 3 is a diagram showing another example of the FG pattern shown in FIG.

4A and 4B are diagrams showing leakage magnetic flux from a rotor magnet, wherein FIG. 4A shows leakage magnetic flux in a conventional example, and FIG. 4B shows leakage magnetic flux in the present embodiment.

FIG. 5 is a front sectional view of a DC motor having a frequency generator according to a conventional example.

[Explanation of symbols]

2 ... bracket 4 ... stator 6
..Stator core 8 ... Amateur coil 10,12 ... Bearing
14 ... shaft 16 ... hub 16A ... hub 16B ...
Side wall 18 ... Yoke 20 ... Rotor magnet 22 ... Clamp magnet 24 ... Optical disk 26 ... Back yoke 28 ... FG magnet 29 ... Side wall 30 ... Printed circuit board 32 ...
・ FG pattern 34 ・ ・ ・ Hall element 36 ・ ・ ・ Lead wire 38
... Reference planes 44, 44a, 44b ... Detours 46, 46a,
46b: Notch 48: Land

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-10825 (JP, A) JP-A-3-104072 (JP, U) JP-A-63-117279 (JP, U) (58) Investigation Field (Int.Cl. ⁷ , DB name) H02K 29/14 H02K 21/24

Claims (1)

(57) [Claims] 1. A bracket, a stator having an armature coil fixed to the bracket, a rotating shaft rotatably provided with respect to the bracket, a rotor magnet rotatable with the rotating shaft, and the rotating shaft. A FG magnet for a frequency generator rotatable with the FG magnet, and a printed circuit board provided on the bracket, and a sawtooth FG disposed on the printed circuit board in a substantially circular shape facing the FG magnet. In a DC motor provided with a pattern, a detour is provided by detouring a part of the detection pattern on the printed circuit board, a notch is formed by notching a substrate in the detour, and a lead wire from the amateur coil is formed. A frequency generator which is inserted into the notch and led out of the motor through a space between the notch and the bracket. DC motor having a machine.