JP2006239611A - Electromagnetic-acoustic converter provided with flat brushless vibration motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic-acoustic converter which employs, as a motor, a flat brushless vibration motor incorporating a sensor and a drive circuit, thereby has a simplified feed structure, is made thin, has a long life and enables a detent torque generation part from not being affected by an exciting magnet of a loudspeaker even when the motor is used as a magnet pole of the loudspeaker side. <P>SOLUTION: The exciting magnet is placed on a flange of a housing H of the motor and the motor M is attached to the loudspeaker housing using the flange. A plurality of the dent torque generation parts 8b each having a notched tip part are provided radially from the center part in a radial direction at an open angle equal to that of the magnetic pole of the motor side magnet 9 so as to be magnetically separated from the magnetic field of the exciting magnet and are arranged to be positioned on a nonmagnetic body part 88 of a bracket. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electromagnetic acoustic transducer (commonly known as a microspeaker), and more particularly to a so-called 2-in-1 type equipped with a flat brushless vibration motor as a silent alarm means.

Conventionally, a pair of plate-like elastic bodies are supported by a frame so as to face each other, a magnetic field generator composed of a yoke and a magnet is attached to one plate-like elastic body, and a ring-like elastic body is attached to the other film-like elastic body. A movable voice coil is attached, and the coil is arranged in the magnetic field of the magnetic field generator so that currents having different frequencies can be switched. (See Patent Document 1)
In addition, there is a type in which a cylindrical vibration motor having an eccentric weight arranged on an output shaft is arranged in a lateral direction to obtain centrifugal vibration as a vibration source. However, with such a configuration, a small electromagnetic acoustic transducer cannot be obtained.
As a countermeasure, there is a built-in motor with a cored type, that is, a radial gap type. (See Patent Document 3)
However, in such a configuration, since it is a cored type and a weight is attached to the output shaft, the posture cannot be lowered, and because of the brush commutator system, it cannot cope with the life of the speaker due to the high rotation motor.
Such an electroacoustic transducer depends on the life of the motor side as a silent alarm means from the speaker side. Therefore, the appearance of a long-life motor is desired, and a thin overall posture is required.
Such a 2-in-1 speaker is affected by the magnetic force of the speaker-side excitation magnet because the motor is a magnetic pole that receives the magnetic field of the single-pole excitation magnet on the speaker side.
In particular, in a single-phase brushless motor with a built-in sensor, a detent torque generating member that is moved at a predetermined position necessary to start the rotor is indispensable. It is easily affected by the magnetic field of the excitation magnet on the side.
JP-A-10-117472 JP 2001-103589 A JP 2003-125474 A

  Therefore, an object of the present invention is to adopt a flat brushless vibration motor with a built-in sensor and drive circuit as a motor, to achieve a simple and thin power supply structure, and to achieve a long life. The unit is not affected by the excitation magnet of the speaker.

In order to solve the above problems, a flat brushless vibration motor disposed in the center of a speaker housing as shown in claim 1 and a ring-shaped movable voice coil facing a radial outer periphery of the motor via a gap A vibration thin plate having one end of the coil disposed and having an outer periphery disposed on the speaker housing, and a ring-shaped excitation magnet disposed on the housing via a gap around the outer periphery of the movable coil. The flat vibration motor includes a single-phase air-core armature coil as a stator, a drive circuit member driven by one sensor, a stator base on which these members are mounted, and an eccentric rotor. A detent torque generator for stopping at a predetermined position, and the eccentric rotor includes an axial air gap type magnet disposed in a rotor case, and a front end of the magnet on the outer periphery of the magnet. And an eccentric weight disposed in the rotor case, and is housed in a housing together with a shaft supporting the eccentric rotor, and a part of the housing extends radially downward as a flange. Is mounted on the speaker housing by using the flange, and the detent torque generating portion is magnetically isolated from the magnetic field of the exciting magnet via the motor housing.
Specifically, as shown in claim 2, a plurality of the detent torque generators are provided radially in the radial direction from the center, approximately equal to the magnetization opening angle of the magnetic poles of the axial gap type magnet to be combined or an integral multiple thereof. As the magnetically isolated means, the tip may be separated from a member constituting the housing and disposed on a non-magnetic part constituting a part of the housing.
According to a third aspect of the present invention, it is preferable that the nonmagnetic portion is a nonmagnetic metal body and a detent torque generating member is attached thereto.

According to the first aspect of the present invention, since the detent torque generating member is isolated from the motor housing, the magnetic field of the excitation magnet reaches the motor housing and does not reach the detent torque generating member, and only the magnetic field of the rotor magnet of the motor. Will be properly received and fulfill the predetermined function.
According to the second and third aspects of the invention, the detent torque generating portion can be accurately arranged with high strength.

A drive circuit member that is driven by a single-phase air-core armature coil and one sensor as a stator, and a detent torque generating member that stops the eccentric rotor at a predetermined position, are built in the rotor case. A magnet disposed on the outer periphery of the magnet and an eccentric weight disposed on the rotor case and housed in the housing, and a part of the housing extends radially downward as a flange. The excitation magnet base is mounted and attached to the speaker housing by using the flange, and the detent torque generator is radially radial from the center so as to be magnetically isolated from the magnetic field of the excitation magnet. A plurality of motor side magnets are provided according to the opening angle of the magnetic pole, and the tip is isolated from the housing. Is it is arranged to position the non-magnetic portion of the housing.
FIG. 1 is a cross-sectional view of an electromagnetic acoustic transducer according to the present invention. Example 1
FIG. 2 is a plan view of one member of the motor of FIG.

As shown in FIG. 1, an electroacoustic transducer S of the present invention includes a shallow cylindrical resin speaker housing 1, a flat brushless vibration motor M arranged in the center and incorporating an eccentric rotor, A ring-shaped movable voice coil 2 having a multi-layer solenoid type, and one end of the coil disposed on the outer periphery of the synthetic resin with the outer periphery disposed on the housing. A film-like vibrating thin plate 3 and a ring-like exciting magnet 4 disposed on the housing through a gap on the outer periphery of the movable voice coil 2 are provided. Although not shown, the terminal of the movable voice coil 2 is attached to the vibration thin plate 3 by bonding or the like, and is led out to the feeding terminal portion B through a part of the side surface of the speaker housing 1.
Each of these members is covered with an inverted dish-like cap 5 attached so as to press the outer periphery of the vibration thin plate 3 into the resin speaker housing 1 at the outer peripheral portion. Here, the cap is made of non-magnetic stainless steel, and is provided with a large number of sound emitting holes 5a for guiding sound generated from the vibration thin plate to the outside. Here, since the vibration thin plate 3 is extremely thin, it is simplified and represented by a single solid line.

The motor M constituting the present invention is a Hall sensor type single-phase brushless motor. As is well known, a single-phase brushless motor requires that the rotor be stopped at a predetermined position in order to start itself. However, if a magnetic material is used as it is for the case 6 and the bracket 7 constituting the housing H, it is powerful. Since it is difficult to start up due to the magnetic force of the magnet, it is necessary to secure a large gap. However, in order to reduce the thickness, the bracket that constitutes a part of the housing is usually non-magnetic except for the detent torque generating portion 8b. It is necessary to make a body. If the thickness is about 2 mm, the rotor case holding the magnet must be thin, and the leakage flux on the side opposite to the air gap increases. The case 6 covering such a rotor is also non-magnetic. It is necessary to adopt. However, if the case 6 is made non-magnetic, the magnetic path of the excitation magnet 4 on the speaker side cannot be configured. Therefore, a magnetic material must be provided at least on the side periphery. Therefore, in this embodiment, the nonmagnetic plate 6b is inserted only in the ceiling portion facing the magnet of the rotor.
In such a motor M, the case 6 constituting the housing H is integrally formed with a flange 6a formed in the radial direction from the lower portion and superimposed on the flange 7a extending in the radial direction of the bracket 7. The bracket 7 is composed of a part of the detent torque generating member 8 and an end bracket 88 made of a nonmagnetic metal integral with the detent torque generating member 8.
As shown in FIG. 2, the detent torque generating member 8 includes a thin portion as the detent torque generating portion 8 b and a flange 88 a of the end bracket 88 in order to appropriately receive the magnetic force of the axial gap magnet 9 described later. It consists of an integrated flange 8a and a central shaft fixing portion 8c. The four detent torque generators 8b formed radially with the opening angle of the magnetic pole approximately equal to or an integral multiple of the opening angle (here, the axial gap type magnet is 6 poles, 60 ° and 120 °) It is attached to the end bracket 88 by spot welding, adhesion, or the like via the guide 8d so as to be positioned. A speaker-side excitation magnet 4 is mounted on each of the integrated flanges 6a, 7a, 88a, and is attached to the speaker housing 1 as a motor M using the flange. That is, this motor is arranged at the center of the speaker and serves as a magnetic pole that receives the monopolar magnetic field of the exciting magnet 4.
A feature of the present invention is that a notch 8e is provided in the detent torque generating member 8 so that the magnetic field of the excitation magnet 4 of the speaker does not affect the detent torque generating portion 8b. The notch 8e can be easily cut in a big shape even after being integrated with the end bracket 88, but may be cut out together with the nonmagnetic end bracket 88.
In this way, since the detent function depends only on the axial gap type magnet on the motor side, the stationary operation becomes stable.
On the other hand, in the eccentric rotor R, the axial gap magnet 9 is bonded to the thin rotor yoke 10. The thin rotor yoke 10 has a flat portion 10h that receives the magnetic field of the axial gap type magnet 9, and an outer diameter side hanging portion 10a and an inner diameter side hanging portion 10b that are integral with the flat portion 10h. Since 9 is enclosed, strong adhesion is obtained.
In this thin rotor yoke 10, a flange portion 10c is formed in the radial direction from the outer diameter side hanging portion 10a to the entire circumference. The flange has an outer diameter that is concentric with the center of rotation, and constitutes a magnetic balance means against an external magnetic field.
The arc-shaped eccentric weight W is placed on the flange so that the movement in the radial direction is restricted by the concave / convex combination, and is fixed by fitting adhesive or welding in the concave / convex fitting. The adhesive is firmly fixed to the rotor yoke at the lower surface and the inner diameter surface of the arc-shaped weight. The movement of the eccentric weight W in the radial direction is restricted by the uneven fitting. Since the outer circumference of the axial gap type magnet 9 is covered with the hanging part on the side circumference of the rotor yoke 10, the leakage of magnetic flux to the case 6 is reduced, but furthermore, there is a space for arranging the eccentric weight W. The magnetic flux leaking outward in the radial direction of the axial gap type magnet is not leaked outward by the collar portion which is a magnetic balance member, and the magnetic flux leakage of the excitation magnet 4 on the speaker side is less likely to be received.
The eccentric rotor R thus configured is rotatably mounted via a bearing 13 in advance on a shaft 12 whose base end is fixed by laser welding L from the outside to the bracket side, here the center 8c of the detent torque generating member 8 in advance. The Similarly, the tip of the shaft 12 received at the center of the case 6 is also laser welded Y after the eccentric rotor R is mounted. Similarly, the bracket side is also laser-welded to the opening of the case 6. Therefore, since the motor has a monocoque structure, the strength is ensured even with a thin member.
A stator for driving the eccentric rotor R is disposed on a detent torque generating member 8 attached to the non-magnetic end bracket 88 by spot welding or the like, and a stator base 11 made of a flexible substrate above the detent torque generating member 8. Two connected single-phase air-core armature coils (only one is shown) 14 and a drive circuit member D arranged so as not to overlap with the coil 14 (here, one Hall sensor is incorporated) Drive).
Therefore, since the brushless motor M configured in this way has the drive circuit member D built in, the power supply terminal portion B needs only two positive and negative terminals, and four power supply terminals together with the two terminals through which the movable voice coil 2 is energized. Therefore, the configuration is extremely simple.

The present invention exemplifies a fixed shaft type as a flat brushless vibration motor, but can also be applied to a shaft rotating type. Since the detent torque generating portion only needs to be magnetically isolated from the housing, the non-magnetic end bracket may be embedded in the resin so that the detent torque generating portion 8b becomes a skeleton.
The present invention can take various other embodiments without departing from the technical idea and characteristics thereof. Therefore, the above-described embodiment is merely an example and should not be interpreted in a limited manner. The technical scope of the present invention is indicated by the claims, and is not restricted by the text of the specification.

It is principal part sectional drawing of the electromagnetic acoustic transducer of this invention. Example 1 It is a top view of one member of the flat type brushless vibration motor of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Speaker housing 2 Movable voice coil 3 Vibration thin plate 4 Excitation magnet 5 Cap 6 Case 7 Bracket 7a Flange 8 Detent torque generation member 8b Detent torque generation part 9 Magnet 10 Rotor yoke 11 Stator base 12 Shaft 13 Bearing 14 Single-phase air-core armature coil M Flat type brushless vibration motor R Eccentric rotor S Electromagnetic acoustic transducer H Housing

Claims (3)

  A flat brushless vibration motor disposed in the center of the speaker housing, a ring-shaped movable voice coil that faces the outer periphery in the radial direction of the motor via a gap, and one end of the coil is disposed, and the outer periphery is the speaker. An electromagnetic acoustic transducer comprising a vibration thin plate disposed in a housing and a ring-shaped excitation magnet disposed in the housing via a gap around the outer periphery of the movable coil, wherein the flat vibration motor is The stator includes a single-phase air-core armature coil, a drive circuit member driven by a single sensor, a stator base on which these are mounted, and a detent torque generator that stops the eccentric rotor at a predetermined position. The eccentric rotor includes an axial gap magnet disposed in the rotor case, and an eccentric weight disposed in the rotor case on the outer periphery of the magnet. The shaft is stored in a housing together with a shaft that supports the eccentric rotor, and a part of the housing extends downward as a flange in the radial direction. The base of the exciting magnet is placed on the flange and the flange is used. The electromagnetic acoustic transducer having a flat brushless vibration motor is attached to the speaker housing, and the detent torque generator is magnetically isolated from the magnetic field of the exciting magnet via the motor housing. .   A plurality of the detent torque generators are provided radially in the radial direction from the center approximately equal to the magnetization opening angle of the magnetic poles of the axial gap type magnets to be combined or an integral multiple thereof, and the tip is as a means for magnetic isolation 2. An electromagnetic acoustic transducer comprising the flat brushless vibration motor according to claim 1, wherein the electromagnetic acoustic transducer is separated from a member constituting the housing and disposed on a non-magnetic part constituting a part of the housing. 3. The electromagnetic acoustic transducer having a flat brushless vibration motor according to claim 2, wherein the non-magnetic part is a non-magnetic metal body and a detent torque generating member is attached.

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