JPH0655027B2 - Brushless motor - Google Patents

Description

Description: (a) Field of Industrial Application The present invention relates to a brushless motor, and more particularly to a brushless motor that reduces noise generated when switching the energization of a drive coil.

(B) Conventional Technology Conventionally, a brushless motor, in which a plurality of drive coils are mounted on a stator yoke plate and a rotor having a magnet is arranged to oppose the drive coils via an axial gap, is, for example, It is known from Japanese Patent Publication No. 56-57687.

Such a conventional brushless motor will be described with reference to the drawings. As shown in FIG. 4, a printed board having a plurality of drive coils (2) attached to one main surface of a stator yoke plate (1).
A rotor having a ring-shaped magnet (4) that is formed by stacking (3)
The rotating shaft (6) is rotatably supported so that the rotating shaft (6) opposes the driving coil (2) through the axial gap, and the rotating shaft (6)
It is known that a rotary head (7) is attached to the tip of the. Reference numeral (8) is a housing for supporting the rotary shaft (6) and for mounting the brushless motor on the chassis of the device.

In such a brushless motor, the rotor (5) is rotated by switching and driving each drive coil (2), and the rotary head attached to the tip of the rotary shaft (6) of the rotor (5).
Rotate (7).

However, in such a brushless motor, it is common to digitally switch a plurality of drive coils (2) in order to rotate the rotor (5). Signals are easily generated.

This steep pulse signal is also induced in the rotor (5) and transmitted to the rotary head (7) via the rotary shaft, which causes noise during recording / playback of the recording / playback device.

Furthermore, when the level of the steep pulse signal is high,
There is also a problem in terms of safety because a discharge phenomenon easily occurs between the rotor (5) and the rotary head (7) and the outside.

(C) Problems to be Solved by the Invention The present invention has been made to solve such conventional drawbacks, and suppresses the influence of a steep pulse signal generated at the time of switching driving of the drive coil, and An object of the present invention is to provide a brushless motor capable of ensuring smooth rotation.

(D) Means for Solving the Problems In order to solve the problems, the present invention provides a printed circuit board having a conductive pattern provided on the rotor-side end surface of the drive coil, and the conductive pattern provided in the conductive pattern. And a non-conductive portion that suppresses the generation of an eddy current when the magnetic flux penetrates the pattern.

(E) Action By such means, a steep pulse signal generated when the drive coil is switched and driven is absorbed by the conductive pattern of the printed circuit board. In addition, since the non-conductive portion is provided in this conductive pattern, the generation of eddy current when the magnetic flux penetrates the conductive pattern is suppressed, and the presence of the printed board may reduce the magnitude of the magnetic flux. Absent.

Further, it is conceivable that the pulse signal absorbing member is formed of, for example, a conductive foil plate instead of the printed board, and the non-conductive portion is formed by a notch formed by pressing, but a large number of notches are formed by pressing. Although it is difficult to form, and there is a possibility that it may be short-circuited with the drive coil due to burrs on the cutting edge due to press working, there is no such inconvenience when forming the absorbing member on a printed circuit board.

(F) Embodiment An embodiment of the present invention will be described with reference to the drawings. The same parts as those in the conventional example are designated by the same reference numerals.

Fig. 1 is a half-section front view of a brushless motor, 8m / m
The case where it is applied to a drive source of a video head is shown.

In the drawing, the housing (8) has a stator yoke plate (1).
Is attached, and on the stator yoke plate (1),
A printed circuit board (3) for a drive circuit in which a plurality of drive coils (2) are annularly attached is stacked.

The drive coil (2) forms a three-phase stator coil, and each phase is constituted by two ring-shaped drive coils opposed to each other via the rotary shaft (6) as shown by a broken line in FIG. It

Returning to FIG. 1, the rotor (5) has an annular magnet (4), which is arranged so as to oppose the drive coil (2) through a slight axial gap, and its rotation shaft ( 6) penetrates the stator yoke plate (1) and the housing (8), and is rotatably supported by this.

Between the drive coil (2) and the rotor (5), the drive coil
The printed circuit board (9) is attached to the end face of the rotor (2) on the rotor side with an adhesive. FIG. 2 is a plan view of the stator yoke plate to which the drive coil (2) and the printed board (9) are attached, and FIG. 3 is a sectional view of the printed board (9).

As is clear from FIG. 3, the printed circuit board (9) is an insulating foil (1
The conductive pattern (11) is formed on almost the entire surface of (0) by a printing technique, and is formed as a flexible printed circuit board in the embodiment. Conductive pattern (11) is a lead wire
(12) is connected to the ground via the stator yoke plate (1). As is apparent from FIG. 2, a plurality of non-conductive parts (13) are formed on the conductive pattern (11) in a circular arc shape and concentrically with the rotation axis (6) as a center. In this case, the concentric belt-like parts formed and partitioned between the adjacent non-conductive parts (13) (13)
(14) is for the magnetic pole number 2p of the magnet (4) of the rotor (5)
They are short-circuited to each other at a position of 360 × n / p degrees (n is an integer of p or less). In the embodiment, the number of magnetic poles of the magnet (4) is 6, and the concentric belt-shaped portion (14) is short-circuited at a position of 120 degrees.

When the strip portions (14) are short-circuited at 360 × n / p degrees in this manner, the eddy currents generated by the rotation of the magnet (4) in the strip portions are canceled out in the same phase.

In addition, the width of the non-conductive portion (13) is preferably 0.1 mm or less in order to prevent leakage of magnetic flux from the non-conductive portion and steep pulse signal leakage that occurs during switching drive of the drive coil (2). .

The object of the present invention can be achieved even when the non-conductive portion (13) is provided not in the circumferential direction but in the radial direction.

(G) Effect of the Invention A brushless motor according to the present invention is a brushless motor in which a plurality of drive coils are mounted on a stator yoke plate, and a rotor having a magnet is arranged opposite to the drive coil via an axial gap. A printed circuit board provided on the rotor-side end surface of the drive coil and having a conductive pattern; and a non-conductive section provided in the conductive pattern for suppressing generation of eddy current when magnetic flux penetrates the conductive pattern. Therefore, it has the following effects.

That is, the steep pulse signal generated by the switching drive of the drive coil is absorbed by the conductive pattern of the printed circuit board and is less likely to be induced in the rotor. Although the eddy current tends to flow through the conductive pattern, the conductive pattern is provided with the non-conductive portion that suppresses the generation of the eddy current when the magnetic flux penetrates, so that the generation of the eddy current is suppressed. Further, since the generation of eddy current is suppressed on the printed circuit board and the steep pulse signal is absorbed, it is easy to attach the absorbing member to the end face of the drive coil on the rotor side, and short circuit between the drive coil and the like. Does not cause the problem.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to FIG. 3 show an embodiment of the present invention. FIG. 1 is a front view of a brushless motor half-cut, and FIG. 2 is a stator yoke to which a drive coil and a printed circuit board are attached. A plan view of the plate and FIG. 3 are cross-sectional views of the printed circuit board. FIG. 4 is a half sectional front view of a conventional brushless motor. (1) …… stator yoke plate, (2) …… drive coil, (4)…
… Magnet, (5) …… Rotor, (11) …… Conductive pattern, (9) …… Printed circuit board, (13) …… Non-conductive part, (14)…
… Strips.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuyoshi Amao 2-18 Keihan Hondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Hitoshi Yokomizo 2-18 Keihan-hondori, Moriguchi-shi, Osaka Sanyo Denki Co., Ltd. (72) Inventor Yoshihisa Takahashi 2-122, Mampei-cho, Kumagaya-shi, Saitama, Kumagai Precision Co., Ltd. (72) Inventor Takeshi Osaki 2-122, Mampei-cho, Kumagaya-shi, Saitama Pref.

Claims (1)

[Claims] 1. A brushless motor in which a plurality of drive coils are mounted on a stator yoke plate, and a rotor having a magnet is arranged so as to face the drive coils with an axial gap therebetween, on an insulating foil (10). Conductive foil over almost the entire surface, leaving a plurality of arc-shaped and concentric non-conductive parts (13) around the rotation axis
A brushless motor characterized in that a printed board on which (11) is formed is provided on an end surface of the drive coil on the rotor side.