JP2003009283A - Flat speaker and electronic device with the flat speaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flat speaker that is applicable to a small-sized electronic device or the like and that has a low profile and a small size, and to provide an electronic device having the flat speaker. SOLUTION: The flat speaker is provided with a gap forming section 50 that is disposed to places to which a yoke 44 and a back yoke 46 oppose and that produce a repulsive force and forms a gap G between a voice coil 64 and a voice coil driving magnet 48 and with a diaphragm 40 that is fixed closely to the yoke 44 and whose end is fixed to the back yoke 46 while covering the yoke 44 and that makes vibration to the back yoke 46 together with the yoke 44 and a flexible printed circuit board 60 when power supply is applied to the voice coil 64.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat speaker optimal for use in an electronic device and an electronic device having the flat speaker.

[0002]

2. Description of the Related Art A speaker used in a conventional electronic device has a permanent magnet, a yoke, a frame, a voice coil, a cone, etc., and each element has an independent structure.

[0003]

This type of electrodynamic loudspeaker has the drawback that it is difficult to make it thin and compact because each component is formed large independently as described above. Therefore, an object of the present invention is to solve the above problems and provide a flat speaker that can be used in a small electronic device or the like and can be thinned and downsized, and an electronic device having a flat speaker.

[0004]

According to a first aspect of the present invention, a voice coil formed on a flexible printed circuit board and one surface side of the flexible printed circuit board are closely attached and fixed, and the voice coil is energized. And a yoke serving as an electromagnet, a back yoke that is spaced apart from the other surface of the flexible printed circuit board, a position corresponding to the voice coil in the back yoke, and the voice coil is energized. A voice coil driving magnet that moves the flexible printed circuit board and the yoke by generating an attractive force and a repulsive force between the yoke and the yoke and the back yoke are arranged to face each other to generate a repulsive force, A gap forming portion that forms a gap between the voice coil and the voice coil driving magnet; A diaphragm whose end portion is fixed to the back yoke in a state of covering the yoke by closely fixing to the yoke, and when the voice coil is energized, the diaphragm is attached to the back yoke together with the yoke and the flexible printed circuit board. And a diaphragm that vibrates in response to the diaphragm.

In the first aspect, the voice coil is formed on the flexible printed board. The yoke is fixed in close contact with one surface of the flexible printed board. The back yoke is arranged on the other surface side of the flexible printed board with a space. The voice coil driving magnet is arranged in a position corresponding to the voice coil in the back yoke, and when the voice coil is energized, an attractive force and a repulsive force are generated between the voice coil driving magnet and the yoke of the electromagnet to drive the flexible printed circuit board and the yoke. The gap forming portion is arranged at a position facing the yoke and the back yoke. The gap forming unit generates a repulsive force between the voice coil and the voice coil driving magnet, forms a gap between the voice coil and the voice coil driving magnet, and floats the voice coil from the magnet. The diaphragm is fixed in close contact with the yoke so that the end of the diaphragm is fixed to the back yoke while covering the yoke. When the voice coil is energized, the diaphragm vibrates with respect to the back yoke together with the yoke and the flexible printed circuit board. The flexible printed circuit board, the yoke, and the diaphragm are thin plate-shaped members, and the planar speaker is thin and small.

According to a second aspect of the present invention, in the flat speaker according to the first aspect, the gap forming portion includes a first hard magnetic magnet formed in the yoke and a second hard magnetic magnet formed in the back yoke. A magnetic magnet is provided, and the first hard magnetic magnet and the second hard magnetic magnet have the same facing poles. In the second aspect, since the facing poles of the first hard magnetic magnet and the second hard magnetic magnet of the gap forming portion are the same pole, the first hard magnetic magnet and the second hard magnetic magnet repel and generate a repulsive force. A gap can be reliably formed between the voice coil and the voice coil driving magnet.

According to a third aspect of the present invention, in the flat speaker according to the first aspect, a plurality of the voice coils are formed on the flexible printed board, and the voice coil driving magnets are located at positions corresponding to the voice coils. Is formed in.

According to a fourth aspect of the present invention, there is provided an electronic device having a flat speaker, wherein the flat speaker is fixed to a voice coil formed on a flexible printed circuit board and one surface of the flexible printed circuit board in close contact with each other. , A yoke that becomes an electromagnet when the voice coil is energized,
A back yoke, which is arranged on the other surface side of the flexible printed circuit board with a space, and a position corresponding to the voice coil in the back yoke. When the voice coil is energized, an attractive force is generated between the back yoke. And a voice coil driving magnet for moving the flexible printed circuit board and the yoke to generate a repulsive force, and a repulsive force generated at a position facing the yoke and the back yoke to generate the repulsive force. A gap forming portion that forms a gap between drive magnets, and a diaphragm whose end portion is fixed to the back yoke while covering the yoke by closely fixing the gap to the voice coil. When energized,
An electronic device having a flat speaker, comprising: the yoke, the flexible printed circuit board, and a diaphragm that vibrates with respect to the back yoke.

In the present invention, the voice coil is formed on the flexible printed board. The yoke is fixed in close contact with one surface of the flexible printed board. The back yoke is arranged on the other surface side of the flexible printed board with a space. The voice coil driving magnet is arranged in a position corresponding to the voice coil in the back yoke, and when the voice coil is energized, the flexible printed circuit board and the yoke are moved between the magnet and the yoke of the electromagnet. The gap forming portion is arranged at a position facing the yoke and the back yoke. The gap forming unit generates a repulsive force between the voice coil and the voice coil driving magnet, forms a gap between the voice coil and the voice coil driving magnet, and floats the voice coil from the magnet. The diaphragm is fixed in close contact with the yoke so that the end of the diaphragm is fixed to the back yoke while covering the yoke. When the voice coil is energized, the diaphragm vibrates with respect to the back yoke together with the yoke and the flexible printed circuit board. The flexible printed circuit board, the yoke, and the diaphragm are thin plate-shaped members, and the planar speaker is thin and small.

According to a fifth aspect of the invention, in the electronic device having the flat speaker according to the fourth aspect, the gap forming portion is formed in the first hard magnetic magnet formed in the yoke and in the back yoke. And a second hard magnetic magnet, wherein the first hard magnetic magnet and the second hard magnetic magnet have the same facing poles. Claim 5
Then, since the facing poles of the first hard magnetic magnet and the second hard magnetic magnet of the gap forming portion are the same pole,
The hard magnetic magnet and the second hard magnetic magnet repel each other to generate a repulsive force, so that a gap can be reliably formed between the voice coil and the voice coil driving magnet.

According to a sixth aspect of the invention, in the electronic device having the flat speaker according to the fourth aspect, a plurality of the voice coils are formed on the flexible printed circuit board.
The voice coil driving magnet is formed at a position corresponding to the voice coil.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The embodiment described below is a preferred specific example of the present invention,
Although various technically preferable limitations are given, the scope of the present invention is not limited to these forms unless otherwise specified in the description below.

1 and 2 show a mobile phone as an example of an electronic device having a flat speaker. Cell phone 10
Is a housing 12, a battery 100, a display unit 16,
It has an antenna 14, a flat speaker 30, a microphone 20, an operation unit 18, and the like. The battery 100 is a battery for supplying power to the mobile phone 10. The housing 12 is
It has a front part 24 and a rear part 26. As shown in FIG. 2, the battery 100 is detachably attached to the lower portion of the rear portion 26 and the rear surface of the front portion 24. The display unit 16 is a unit for displaying various information, and for example, a liquid crystal display device can be used. The flat speaker 30 is for listening to, for example, a voice notification sound, and the microphone 20 is a portion for inputting the voice of the operator. Operation unit 18
Is a numeric keypad 18C, a button 18A for making a call
And a button 18B for hanging up the telephone.

The flat speaker 30 shown in FIG.
Is disposed inside the front portion 24 of the. The front portion 24 has a plurality of holes 24H corresponding to the flat speaker 30.
Are formed. 3 is a perspective view showing a preferred embodiment of the flat speaker 30, and FIG. 4 is an exploded perspective view of the flat speaker 30 of FIG. FIG. 5 shows a flat speaker 3
6 is a plan view of No. 0, and FIG. 6 is a diagram showing an example of a sectional structure of the flat speaker 30. In FIG. 5, the central portion of the diaphragm 40 of the flat panel speaker 30 is cut away. Figure 3
As shown in FIG. 3, the flat speaker 30 is a flat plate-shaped, thin and small speaker. The flat speaker 30 is, for example, a small thin speaker that can be sufficiently housed in the housing 12 of the mobile phone 10 of FIG. 1 which is a small electronic device.

As shown in FIGS. 3 and 4, the flat speaker 30 is used.
Is a diaphragm 40, a yoke 44, a back yoke 4
6, a voice coil driving magnet 48, a gap forming portion 50, and a flexible printed circuit board 60. The back yoke 46 is formed by bending a plate of a magnetically permeable material such as stainless steel, for example, SUS430, and has a bottom portion 46A and four side portions 46B. The side portions 46B are box-shaped members formed so as to stand up from the four corners of the bottom portion 46A.

On the inner surface side of the bottom portion 46A of the back yoke 46, for example, four square plate-shaped magnets 48 for driving the voice coil are fixed by an adhesive, for example. These magnets 48 for driving the voice coil are arranged at intervals. Between the magnets 48, a second portion is formed on the inner surface side of the bottom portion 46A of the back yoke 46.
The hard magnetic magnet 72 is formed in, for example, a + shape. In this way, the back yoke 46 serves as a holder for holding the magnet 48 for driving the voice coil and the second hard magnetic magnet 72.

The diaphragm 40 shown in FIGS. 3 and 4 is, for example, a resin film and has a thickness of 0.1 m as an example.
m polyimide film. This diaphragm 40
40A of the four corners are the side portions 46B of the back yoke 46.
Is fixed to the end surface 46C of the sheet using an adhesive.
The diaphragm 40, the yoke 44, and the flexible printed circuit board 60 are laminated and fixed by an adhesive in the order of the diaphragm, the yoke, and the flexible printed circuit board. The diaphragm 40 in FIG. 4 is, for example, a rectangular member. The yoke 44 of the soft magnetic magnet is a square member having a size slightly smaller than that of the diaphragm 40. The soft magnetic magnet yoke 44 becomes an electromagnet when the voice coil 64 of the flexible printed circuit board 60 is energized. This yoke 44 has a thickness of, for example, 0.2 mm secured by evaporating or coating particles of, for example, strontium ferrite. The yoke 44 of the soft magnetic magnet is a member for forming the magnetic field from the magnet 48 for driving the voice coil on the side of the back yoke 46 in a direction intersecting the direction of the current of the voice coil 64.

At the center of the yoke 44 of the soft magnetic magnet shown in FIG. 4, for example, a + type first hard magnetic magnet 71 is formed. This first hard magnetic magnet 71 and another 1
The two second hard magnetic magnets 72 are provided in the gap forming portion 50.
Are configured. The gap forming portion 50 is a gap forming portion for forming a gap G between the flexible printed circuit board 60 and the voice coil driving magnet 48 as shown in FIGS. 7 and 6. The magnetic poles on the opposite sides of the first hard magnetic magnet 71 and the second hard magnetic magnet 72 are the same pole. In the example of FIG. 7, the poles where the first hard magnetic magnet 71 and the second hard magnetic magnet 72 face each other are magnetized as N poles. As a result, the first hard magnetic magnet 71 and the second hard magnetic magnet 7 are provided along the E direction.
2 generates a repulsive force, so the flexible printed circuit board 6
A gap G can be formed between the voice coil 64 of 0 and the magnet 48 for driving the voice coil. By forming the gap G, the cone portion (vibration plate) including the diaphragm, the yoke, and the flexible printed circuit board is floated from the magnet 48. This gap G is 0.3 mm, for example.

The area of the region 44S of the yoke 44 of the soft magnetic magnet shown in FIG.
It is set to be the same as the area of 8. The first hard magnetic magnet 71 and the second hard magnetic magnet 72 are, for example, 150
It is obtained by kneading μm alnico particles with a binder.
The first hard magnetic magnet 71 is kneaded or coated in a cross shape on the yoke 44 of the soft magnetic magnet, for example. Alternatively, the first hard magnetic magnet 71 may be kneaded or coated in a cross shape, for example, on the inner surface 40B of the diaphragm 40. The second hard magnetic magnet 72 can be kneaded or coated in a cross shape between the magnets 48.

The flexible printed circuit board 60 shown in FIG.
It has four voice coils 64. Each of these voice coils 64 has an area corresponding to the area 44S of the yoke 44 of the soft magnetic magnet and the area of the magnet 48 on the back yoke 46 side. The voice coil 64 is
They are connected in series by connecting lines 80 and 81 as shown in FIG. That is, the central portion 6 of the first voice coil 64
4A is connected to the outer portion 64B of the next voice coil 64. The central portion 64C of the voice coil 64 is connected to the outer portion 64D of the next voice coil 64. The central portion 64E of the voice coil 64 is connected to the outer portion 64F of the adjacent voice coil 64. The central portion 64G of the voice coil 64 is connected to the connecting wire 80. As shown in FIG. 4, the connecting wires 80 and 81 are connected to the conducting portion 83.
It is connected to the. The energizing unit 83 is adapted to supply a current according to a voice signal to the voice coil 64 in response to a command from the control unit 84.

One surface 60P of the flexible printed circuit board 60 has the other surface 4 of the yoke 44 of the soft magnetic magnet.
It is closely fixed to the 4R with an adhesive. One surface 44P of the yoke 44 is fixed to the inner surface 40B of the diaphragm 40 with an adhesive. The other surface 60R of the flexible printed board 60 faces the magnet 48 with the gap G shown in FIG. Each of the four voice coils 64 formed on the flexible printed circuit board 60 is made of a copper foil having a thickness of 25 μm, for example, and the width of the copper foil is 0.2 mm, for example, 11 turns. . These four voice coils 64 each having 11 turns are connected in series to secure a total of 44 turns.

In the back yoke 46 and the yoke 44 of the soft magnetic magnet, the magnetic lines of force of the magnet 48 are applied to the voice coil 6.
The magnetic circuit is constructed so as to intersect the current flowing through the magnetic circuit 4. The diaphragm 40, the yoke 44, and the voice coil 64 are integrally laminated and fixed by the adhesive as described above.
The flexible printed circuit board 60 constitutes a cone portion. The cone portion is fixed to the back yoke 46 by using the edge portion 40A of the diaphragm 40. Therefore, the portion of the diaphragm 40 excluding the edge portion 40A, the yoke 44, and the voice coil 64 are
By energizing No. 4, the back yoke 46 can be moved (vibrated) along the movement direction CL.

Next, the operation of the flat speaker 30 having the above configuration will be described. FIG. 8 is a diagram for explaining the operation of the flat speaker 30, and shows one magnet 48 and its peripheral portion as a representative. In FIG. 8, the diaphragm 40, the yoke 44, and the voice coil 64 integrally form a cone portion. A magnet 48 is provided in the back yoke 46. The yoke 44 and the magnet 48 face each other. When an audio signal is given from the control unit 84 to the energizing unit 83, the energizing unit 83 energizes the connection lines 80 and 81 with the current I shown in FIG. 8 based on the audio signal.

It is assumed that the magnet 48 is magnetized to the N pole. When the current I flows through the voice coil 64, the yoke 4
4 becomes the N pole, and repulsive force is generated with the magnet 48 of the N pole,
The cone portion moves upward in the upward direction (CL2). York 4
When 4 becomes the S pole, it attracts the N pole of the magnet 48, so an attractive force is generated between the yoke 44 and the magnet 48, and the cone portion goes down to CL1. That is, when the current I1 flows through the voice coil 64, the yoke 44 becomes the S pole, so that the S pole yoke 44 and the N pole magnet 48 of the diaphragm 40 exert an attractive force, and the cone portion is lowered to CL1. As a result, a cone portion (also referred to as a diaphragm) including the diaphragm 40, the voice coil 64, and the yoke 44 reciprocates with respect to the back yoke 46 along the movement direction CL. Therefore, sound is generated because the air vibrates. Since the edge portion 40A of the diaphragm 40 is fixed to the end surface 46C of the side portion 46B of the back yoke 46, the central portion of the diaphragm 40 excluding the edge portion 40A reciprocates along the movement direction CL.

As shown in FIGS. 6 and 8, the voice coil 6
4, the yoke 44 is the diaphragm 40 and the back yoke 4
Since the size is slightly smaller than the size of 6, the cone portion including the diaphragm 40, the voice coil 64, and the yoke 44 can reciprocate in the back yoke 46 along the movement direction CL. By adopting such a flat type speaker, downsizing unlike the conventional,
The flat speaker 30 can be made thinner, and the flat speaker 30 can be incorporated even in a small electronic device.

In FIG. 8, the yoke 44 of the soft magnetic magnet is an electromagnet, and when the voice coil 64 is energized, it is magnetized to the S pole or the N pole. Magnet 48
Is a permanent magnet. The Coulomb force F generated by the yoke 44, which is an electromagnet, and the magnet 48, which is a permanent magnet, is obtained by multiplying the magnetic amount m1 of the yoke 44 and the magnetic amount m2 of the magnet 48 by the distance r ² between the yoke 44 and the magnet 48. You can get one. The Coulomb force F is the magnitude of the force acting between the magnetic poles of the yoke 44 and the magnet 48.

The present invention is not limited to the above embodiment. The flat speaker according to the above-described embodiment is built in a relatively small mobile phone, but the present invention is not limited to this, and can be installed in other types of electronic devices such as mobile computers.

The shapes of the first hard magnetic magnet 71 and the second hard magnetic magnet 72 of FIG. 4 are not limited to the + type, and it is of course possible to adopt other shapes. Of course, the back yoke 46 may be a rectangular box shape or a circular box shape instead of the square box shape. The winding method of the voice coil 64 is not limited to spirally winding a straight line as shown in FIG. 4, and a curved line may be spirally wound.
Of course, the number of voice coils 64 may be one, two, three, or five or more. The numbers of the yokes 44 and the magnets 48 are set according to the number of the voice coils 64.

[0029]

As described above, according to the present invention,
It can be used for small electronic devices, etc., and can be made thin and compact.

[Brief description of drawings]

FIG. 1 is a front view showing a mobile phone which is an example of an electronic device having a flat speaker of the present invention.

FIG. 2 is a rear view of the mobile phone shown in FIG.

FIG. 3 is a perspective view showing an embodiment of a flat speaker.

FIG. 4 is an exploded perspective view of the flat speaker of FIG.

FIG. 5 is a plan view of a flat speaker.

FIG. 6 is a cross-sectional view of a flat speaker.

FIG. 7 shows a first hard magnetic magnet and a second hard magnetic magnet in the gap forming portion.
The figure which shows the gap obtained by the repulsive force generated by a hard magnetic magnet.

FIG. 8 is a diagram showing an example of movement (vibration) of a flat speaker.

[Explanation of symbols]

10 ... Mobile phone (electronic device), 30 ... Flat speaker, 40 ... Diaphragm, 44 ... Yoke, 4
6 ... Back yoke, 48 ... Magnet for driving voice coil, 50 ... Gap forming portion, 60 ...
Flexible printed circuit board, 64 ... Voice coil,
71 ... First hard magnetic magnet, 72 ... Second hard magnetic magnet, G ... Gap

Claims (6)

[Claims] 1. A voice coil formed on a flexible printed circuit board, a yoke fixedly attached to one surface of the flexible printed circuit board so as to be an electromagnet when energized to the voice coil, and the flexible printed circuit board. And a back yoke arranged at a space on the other surface side of the back yoke, and a position corresponding to the voice coil in the back yoke. When the voice coil is energized, attractive force and repulsive force are generated between the yoke. A voice coil driving magnet for moving the flexible printed circuit board and the yoke; and a repulsive force generated at a position where the yoke and the back yoke face each other to generate a repulsive force. A gap forming part for forming a gap between the yoke and the yoke, and closely fixing the yoke. A diaphragm having an end fixed to the back yoke in a state of covering the yoke, the diaphragm vibrating with respect to the back yoke together with the yoke and the flexible printed circuit board when the voice coil is energized. A flat speaker characterized in that 2. The gap forming portion includes a first hard magnetic magnet formed in the yoke and a second hard magnetic magnet formed in the back yoke, and the first hard magnetic magnet and the first hard magnetic magnet. The flat speaker according to claim 1, wherein the two hard magnetic magnets have the same poles facing each other. 3. The flat speaker according to claim 1, wherein a plurality of the voice coils are formed on the flexible printed board, and the voice coil driving magnet is formed at a position corresponding to the voice coil. 4. An electronic device having a flat speaker, wherein the flat speaker is closely fixed to one side of the voice coil formed on a flexible printed circuit board, and is fixed to the voice coil. A yoke that becomes an electromagnet when energized, a back yoke that is spaced apart from the other surface of the flexible printed circuit board, and a voice coil that is disposed in the back yoke at a position corresponding to the voice coil. When the coil is energized, a voice coil driving magnet for moving the flexible printed circuit board and the yoke by generating an attractive force and a repulsive force between the yoke and the yoke and the back yoke are arranged to face each other to generate the repulsive force. Form a gap between the voice coil and the magnet for driving the voice coil. And a gap forming portion that is fixed to the yoke, and is a diaphragm whose end portion is fixed to the back yoke in a state where the yoke is covered and fixed to the yoke. When the voice coil is energized, the yoke and the yoke are formed. An electronic device having a flat speaker, comprising: a flexible printed circuit board and a diaphragm that vibrates with respect to the back yoke. 5. The gap forming portion has a first hard magnetic magnet formed in the yoke and a second hard magnetic magnet formed in the back yoke, and the first hard magnetic magnet and the first hard magnetic magnet. The electronic device having a flat speaker according to claim 4, wherein the two hard magnetic magnets have the same poles facing each other. 6. The flat speaker according to claim 4, wherein a plurality of the voice coils are formed on the flexible printed board, and the voice coil driving magnet is formed at a position corresponding to the voice coil. Electronics.