JPH09139996A - Electromagnetic driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To drive an object to be driven such as a diaphragm, etc., with large driving force, with efficiency and with good responsiveness to the driving current supplied to the magnetic flux generated from a magnetic circuit part and voice coils by effectively utilizing the driving current. SOLUTION: This device is provided with first and second voice coils 21 and 22 which are wound on the outer peripheral surface of a voice coil bobbin 20 in parallel to the moving direction of the voice coil bobbin 20 and are connected with each other in parallel, by being faced within a magnetic circuit part 15, an object 17 to be driven and the voice coil bobbin 20 integrally provided on the object 7 to be driven and the magnetic gap 16 of the magnetic circuit part 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic drive device for driving and displacing a driven body such as a diaphragm or an objective lens with an electromagnetic drive force.

[0002]

2. Description of the Related Art Heretofore, an electrodynamic speaker device has been known as an electromagnetic driving device for driving a driven body by utilizing an electromagnetic driving force.

In this electrodynamic speaker device, a ring-shaped magnet is arranged on a yoke having a center pole erected in the center so as to surround the center pole, and the center pole is surrounded on the magnet. The magnetic circuit unit includes a ring-shaped top plate, a frame mounted on the magnetic circuit unit, and a diaphragm supported by the frame. The diaphragm has an edge provided on the outer peripheral edge side supported on the outer peripheral edge of the frame, and has a cylindrical voice coil bobbin connected to the central portion thereof. A voice coil is wound around the outer peripheral surface of the voice coil bobbin so as to face a magnetic gap formed between the center pole of the magnetic circuit section and the top plate.

In the speaker device thus constructed, when a driving current corresponding to an acoustic signal is supplied from the sound source to the voice coil, the current flowing through the voice coil and the magnetic flux passing through the magnetic gap of the magnetic circuit section are generated. By virtue of the above action, the diaphragm to which the voice coil bobbin is coupled is vibrated, and sound is reproduced.

[0005]

By the way, the driving force (F) of the electromagnetic drive unit consisting of the magnetic circuit section and the voice coil facing the magnetic gap of the magnetic circuit section is within the magnetic gap of the magnetic circuit section. Density (B) of the magnetic flux passing through the wire, the length (1) of the thin wire constituting the bobbin coil facing the magnetic gap, and the current (I) supplied to this bobbin coil.
The product of F = BlI (1)

Therefore, the magnetic flux generated from the magnetic circuit section and the drive current supplied to the voice coil are effectively used,
In order to efficiently drive the diaphragm as the driven body with a large driving force (F), the length l of the thin wire forming the voice coil wound around the voice coil bobbin is lengthened. In order to lengthen the thin wire 2 which constitutes the voice coil 1, as shown in FIGS. 8 and 9, the voice coil bobbin 3 is wound around the outer periphery of the voice coil in two to four layers. As the thin wire 2 constituting the voice coil 1, a covered wire in which an insulating material is coated on the outer periphery of a conductive wire such as a copper wire, an aluminum wire, or an aluminum wire having copper as a core material is used. By using, the weight of the driven portion including the diaphragm is increased.

A tinsel wire 4, which is a connecting wire connected to an input terminal connected to a signal source such as a sound source, is connected to each end portion 2a, 2b of one thin wire 2 constituting the voice coil 1. To be done.

If the weight of the driven portion including the diaphragm becomes large, the driven portion cannot be driven with good responsiveness to the drive current supplied to the voice coil. In particular, when an electromagnetic drive unit having a long thin wire that constitutes a voice coil is applied to a speaker device, the vibration of the diaphragm cannot be vibrated in a high frequency band with good response to the drive current supplied to the voice coil. , The output sound pressure level drops. As a result, it becomes impossible to construct a speaker device that obtains good sound pressure frequency characteristics from the low frequency band to the high frequency band.

Further, in order to obtain a large driving force (F) by efficiently reducing the weight of the voice coil without making the fine wire constituting the voice coil long, and vibrating the diaphragm efficiently,
It is conceivable to reduce the width of the magnetic gap of the magnetic circuit section and increase the magnetic flux density (B) that penetrates into the magnetic gap. If the magnetic gap is made small, it is necessary to make the voice coil wound around the voice coil bobbin inserted into the magnetic gap thin, and it is necessary to use a thin wire material for the voice coil. If the wire material that constitutes the voice coil is made thin, the electrical resistance of the voice coil increases, and the magnitude of the current that can be supplied to the voice coil is limited, making it impossible to obtain a large driving force (F). . Therefore, it is not possible to construct a speaker device that obtains a sufficient output sound pressure level.

Furthermore, a large amount of magnetic flux is generated in order to reduce the weight of the voice coil and obtain a large driving force (F) and to vibrate the diaphragm efficiently without making the thin wire constituting the voice coil long. It is conceivable to use a large magnet that can be generated. However, increasing the size of the magnet increases the size of the magnetic circuit unit. As a result, the electromagnetic drive device itself, such as a speaker device using this magnetic circuit unit, becomes large.

Therefore, the present invention effectively utilizes the magnetic flux generated from the magnetic circuit section and the drive current supplied to the voice coil to efficiently operate with a large drive force (F) and with good responsiveness to the drive current. It is an object of the present invention to provide an electromagnetic drive device capable of driving a driven body such as a diaphragm.

[0012]

In order to achieve the above-mentioned object, an electromagnetic drive device according to the present invention has a magnetic circuit portion, a driven body, and a voice integrally provided on the driven body. The coil bobbin and the first and second first coils, which face the inside of the magnetic gap of the magnetic circuit unit, are wound around the outer peripheral surface of the voice coil bobbin in parallel in the moving direction of the voice coil bobbin, and are connected in parallel with each other. And a voice coil.

Here, a vibration system including a diaphragm of a speaker device or an objective lens of an objective lens driving device is used as the driven body.

In the electromagnetic drive device according to the present invention, since the first and second voice coils wound around the voice coil bobbin are connected in parallel, the electrical resistance of the voice coil is reduced.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the drawings.

First, a first example in which the present invention is applied to a speaker device will be described.

As shown in FIG. 1, the speaker device according to the present invention has a yoke 12 in which a center pole 11 is erected in the center thereof, and a magnet 13 arranged on the yoke 12 so as to surround the center pole 11. And this magnet 1
An outer magnet type magnetic circuit portion 15 including a ring-shaped top plate 14 arranged so as to surround the center pole 11 is provided on the magnetic pole 3. The magnetic circuit section 15 forms a magnetic gap 16 with a gap in which the center pole 11 and the top plate 14 face each other.

Further, on the top plate 14 constituting the magnetic circuit section 15, the frame 1 in which the diaphragm 17 is supported
8 are attached. The base 18 of the frame 18 is attached to the top plate 14 via fixing screws 14a.

The vibrating plate 17 is formed in a substantially truncated cone shape, and an edge 18 is provided on the outer peripheral edge of the enlarged diameter and is supported on the outer peripheral edge of the frame 14 via a sheet of paper 19. Installed on.

On the base end side of the diaphragm 17, paper is
A voice coil bobbin 20 in which a metal foil, a synthetic resin film, or the like is formed into a cylindrical shape is integrally connected. The base end side of the bobbin bobbin 20 is inserted into the magnetic gap 16 of the magnetic circuit unit 15, and the first and second voice coils 21 and 22 are provided on the outer peripheral surface facing the magnetic gap 16.
Is wound. First and second voice coils 21,
As the wire 22, a thin wire 23, which is a covered wire obtained by coating an insulating material on the outer circumference of a conductive wire such as a copper wire, an aluminum wire, or an aluminum wire having copper as a core material, is used. It is constructed by being wound to the side.

Further, the voice coil bobbin 2 of the diaphragm 17
The voice coil bobbin 20 is provided at the center where 0 is attached.
A dustproof cap 24 is attached so as to close the opening of the. Further, the middle portion of the voice coil bobbin 20 is supported movably in the axial direction of the arrow X direction in FIG. 1 via a damper 25 whose outer peripheral edge is supported by the frame 14. The diaphragm 17 and the cap 24 together constitute a vibration system of the speaker device.

By the way, the first and second voice coils 2
1 and 22 are two thin wires 2 as shown in FIG. 2 and FIG.
3 are wound in parallel in the axial direction of the voice coil bobbin 20, that is, the direction of the arrow X in FIG. 1, which is the vibration direction of the diaphragm 17, and are formed in parallel, and are connected in parallel. These first
To form the second voice coils 21 and 22, one fine wire 23 is wound in the middle of the voice coil bobbin 20 to form the first voice coil 21. Next, another thin wire 23 is wound around the lower end of the voice coil bobbin 20 around which the first voice coil 21 is wound to form the second voice coil 22. The coil ends 22a and 22b of the winding start and winding end of the second voice coil 22 extend on the first voice coil 21 and are bonded onto the first voice coil 21 with an adhesive. Then, the coil end portion 21a at the beginning of winding of the first voice coil 21 and the coil end portion 22a at the beginning of winding of the second voice coil 22 are coupled, and the coil end portion 21b at the end of winding of the first voice coil 21 is connected. And the coil end 22b at the end of winding of the second voice coil 22 are coupled to be electrically connected in parallel to each other. In addition, the coil ends 21a and 22 of the first and second voice coils 21 and 22 which are coupled to each other.
The a and 21b and 22b are connected to tinsel wires 27 and 27 connected to an input terminal 26 to which a connecting wire from a signal source such as a sound source attached to the outer peripheral surface of the frame 14 is connected. A driving current based on an acoustic signal from a signal source input via the input terminal 26 is input to the first and second voice coils 21 and 22 via the tinsel wires 27, 27.

As described above, the speaker device according to the present invention has the first and second voice coils 21 and 22 electrically connected in parallel, and therefore, as shown in FIG. 9 and FIG. and was a common inner circumference r ₁ of the voice coil 1 and the inner peripheral diameter r ₂ that of the conventional speaker device, when to match the winding width w _1, w ₂ for each voice coil bobbin 3, 20, impedance 1 / It becomes 2.

When the impedance on the drive system side including the signal source for driving the speaker device according to the present invention is the same as the impedance on the drive system side of the conventional speaker device, the first and second voice coils 21, Matching the impedance of 22 with the impedance of the drive system side increases the number of turns of the thin wire 23 forming the first and second voice coils 21 and 22 with respect to the voice coil bobbin 20,
Alternatively, it is performed by using a thin wire material having a large electric resistance for the thin wire 23 forming the first and second voice coils 21 and 22. Therefore, the impedances of the drive system side and the impedances of the first and second voice coils 21 and 22 are matched to each other by matching the impedances of the first and second voice coils 21 and 22.
Can be performed by appropriately selecting the number of turns of the thin wire 23 forming the voice coil bobbin 20 and the thickness of the thin wire 23 forming the first and second voice coils 21 and 22.

That is, the first and second voice coils 2
Reference numerals 1 and 22 are formed by a thin wire 23 that is thinner than the thin wire 2 that constitutes the voice coil 1 of the conventional speaker device, and
By increasing the number of turns, impedance matching on the drive system side can be achieved.

Here, two speaker devices having the same driving system impedance are prepared. One of the speaker devices is provided with one voice coil 1 by winding one thin wire 2 around the conventional voice coil bobbin 3 shown in FIGS. 8 and 9 described above. The other speaker device is constructed according to the present invention.

Each speaker device is shown in FIG. 8 and FIG.
, The voice coil 1 wound around the voice coil bobbins 3 and 20, the first and second voice coils 21,
The inner peripheral diameters r ₁ and r ₂ of 22 are set to 16.25 mm, and the voice coil bobbins 3 and 20 are formed from kraft paper having a thickness t ₁ of 0.13 mm. The magnetic circuit section 15 of each speaker device is configured as an outer magnet type as shown in FIG.
A ring-shaped magnet having an outer diameter r ₄ of 60 mm and an inner diameter r ₅ of 26 mm and a thickness t ₂ of 10 mm is used as the magnet 13 constituting the magnetic circuit portion 15. FIG.
As shown in FIG. 4, the voice coil bobbins 3 and 20 of each speaker device are wound around the voice coil bobbins 3 and 20 with a common distance d ₁ between the inner peripheral surface of the voice coil bobbins 3 and 20 and the outer peripheral surface of the center pole 11 that constitutes the magnetic circuit unit 15. The distance d ₂ between the outer peripheral surface of the voice coil 1 or the first and second voice coils 21 and 22 and the inner peripheral surface of the top plate 14 forming the magnetic circuit unit 15 is set to be constant.

Under these conditions, the impedance of the drive system is matched to achieve the voice coil 1 or the first and second voice coils.
When forming the voice coils 21, 22, the first and second voice coils 21, 2 of the speaker device according to the present invention.
2 is a thin wire 23 that is thinner than the thin wire 2 that forms the voice coil bobbin 3 of the conventional speaker device. Since the first and second voice coils 21 and 22 of the speaker device according to the present invention are formed by the thin wires 23, the voice coil 1 or the first and second voice coils 2 are formed.
When the distance d ₂ between the outer peripheral surfaces of the first and the second conductors 22 and the inner peripheral surface of the top plate 14 forming the magnetic circuit unit 15 is constant, the number of windings with respect to the voice coil bobbin 20 can be increased, and the length is long. can do. From the above-mentioned formula (1), the driving force (F) can be increased when the sizes of the magnetic circuit portions 15 are made common.

Here, in the thin wire 2 forming the voice coil 1 of the conventional speaker device, a copper wire having a diameter of 0.12 mm, a copper wire having a diameter of 0.13 mm, and a diameter of 0.13 m.
When using any of the aluminum wires whose core is a copper wire of m, the first and second voice coils 21 and 22 of the speaker device according to the present invention are formed by the thin wire 23 of 0.08 mm in diameter. Thus, the impedance of the drive system is matched. Then, the voice coil 1, the first and second voice coils 2 formed by using the thin wires 2 and 23, respectively.
When a speaker device including Nos. 1 and 22 is prepared and a voice signal having a standard constant frequency and amplitude is input, a conventional voice coil 1 having a diameter of 0.12 mm and a copper wire of 0.13 mm is provided. The output sound pressure level of the speaker device is 91 dB, and the output sound pressure level of the conventional speaker device provided with the voice coil 1 formed of the aluminum wire whose core is a copper wire having a diameter of 0.13 mm is 91 dB. The output sound pressure level of 91.6 dB was obtained in the speaker device according to the present invention, while the output sound pressure level was 0.1 dB.

In the speaker device according to the present invention, the first and second voice coils 2 are formed by the thin wire 23 which is thinner than the thin wire 2 which constitutes the voice coil 1 of the conventional speaker device.
1 and 22 can be formed and the number of turns within the common magnetic gap length can be increased, so that the magnetic circuit unit 15
It is possible to drive with high efficiency for a constant drive current without increasing the size of the device.

Next, the present invention is applied to an objective lens driving device for driving and displacing an objective lens for condensing a light beam emitted from a light source and irradiating the signal recording surface of an optical disc in at least its optical axis direction. This will be described with reference to the second example.

The objective lens driving device according to the present invention is shown in FIG.
And a mounting substrate 51 which is configured as shown in FIG. 6 and which serves as a mounting portion to an optical system block (not shown) and constitutes a yoke of the magnetic circuit portion. On the mounting substrate 51, a pair of fan-shaped outer peripheral side yokes 52, 52 and a pair of inner peripheral side yokes 53, 53 curved in an arc shape are opposed to each other to form a magnetic gap. The magnets 54, 54 are arranged at regular intervals, and the magnets 54, 54 are arranged under the inner yokes 53, 53 to form a magnetic circuit section 55.

On the mounting substrate 51 having the magnetic circuit section 55 as described above, the support shaft 56 is planted so as to be located at the center of the magnetic circuit section 55. A lens holder 58, which is mounted at a decentered position in which the objective lens 57 is separated from the axis, is axially supported by the support shaft 56. The lens holder 58 is rotatable with respect to the support shaft 56 with its axis aligned with the axis of the support shaft 56.
Is slidably supported in the axial direction. The lens holder 58 is supported by the elastic displacement member so that the optical axis of the objective lens 57 is aligned with the optical axis of the optical system block when in the neutral state.

As described above, a pair of openings 59, 59 provided on the mounting substrate 51 are formed on the upper surface of the lens holder 58 supported by the support shaft 56. The upper ends of the inner peripheral side yokes 53, 53 arranged on the mounting substrate 51 face the openings 59, 59. In addition, a cylindrical voice coil bobbin 60 that is inserted into the magnetic gap of the magnetic circuit portion 55 is integrally provided on the lens holder 58 so as to hang down. On the outer peripheral surface of the voice coil bobbin 60, the lens holder 58 is slidably displaced in the axial direction of the support shaft 56 to drive the objective lens 57 in the focusing direction. A tracking drive coil 62 that rotates in the axial direction is provided.

Here, the focus driving coil 61 is
The voice coil bobbin 60 is formed by winding a thin wire around the outer peripheral surface of the voice coil bobbin 60, and as shown in FIG. It is composed of the second voice coils 62 and 63. These first and second voice coils 62, 6
3 is formed by a thin wire 65 made of a coated wire in which the outer periphery of a conductive wire such as a copper wire, an aluminum wire, or an aluminum wire having copper as a core material is coated with an insulating material.

By using the focus driving coil 61 composed of the first and second voice coils 62 and 63 connected in parallel with each other in this way, the magnetic circuit section 5
High-efficiency driving can be performed for a constant driving current without increasing the size of No. 5.

The tracking drive coil 62 is
It is formed by winding a thin wire into a flat rectangular shape, and is arranged on the focus driving coil 61 by bonding or the like.

The focus driving coil 61 and the tracking driving coil 62 are led out of the apparatus through a relay printed wiring board (not shown) provided in the lens holder 58.

[0039]

As described above, the electromagnetic drive device according to the present invention has the first and second windings wound around the voice coil bobbin.
Since the voice coils are connected in parallel, the electrical resistance of the voice coil is reduced. Since the thin wires forming the first and second voice coils can be thin and the number of turns within a fixed magnetic gap length can be increased, the magnetic circuit section is enlarged. It is possible to drive with a high efficiency for a constant drive current.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a speaker device to which the present invention is applied.

FIG. 2 is a perspective view showing a voice coil bobbin and a voice coil which constitute the speaker device.

FIG. 3 is a sectional view of the voice coil bobbin and the voice coil.

FIG. 4 is a cross-sectional view showing a state in which a voice coil is arranged in a magnetic gap of a magnetic circuit section.

FIG. 5 is a perspective view showing an objective lens driving device to which the present invention is applied.

FIG. 6 is a cross-sectional view of the objective lens driving device.

FIG. 7 is a perspective view showing a voice coil bobbin used in the objective lens driving device.

FIG. 8 is a perspective view of a voice coil bobbin used in a conventional speaker device.

FIG. 9 is a sectional view of the voice coil bobbin.

[Explanation of symbols]

 15 magnetic circuit part 16 magnetic gap 17 diaphragm 20 voice coil bobbin 21 first voice coil 22 second voice coil 23 fine wire

Claims (3)

[Claims] 1. A magnetic circuit section, a driven body, a voice coil bobbin integrally provided on the driven body, and a magnetic coil section facing the inside of a magnetic gap of the magnetic circuit section and provided on the outer peripheral surface of the voice coil bobbin. An electromagnetic drive device comprising: first and second voice coils that are wound in parallel in a moving direction of a voice coil bobbin and are connected in parallel to each other. 2. The electromagnetic drive device according to claim 1, wherein the driven body is a vibration system including a diaphragm. 3. The electromagnetic drive device according to claim 1, wherein the driven body is an objective lens.