JP2009124473A - Electrostatic speaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic speaker capable of eliminating the distortion of a sound and adjusting the emitting direction of sound collection/dispersion or the like by a simple configuration. <P>SOLUTION: By reducing the distance of pins 3 by a curve generating mechanism 2, a diaphragm 10 is curved to the front side along a Z axis and the diaphragm 10 is formed into a circular arcuate shape. When the diaphragm 10 is curved, by a deviation absorption part 25, deviation generated between a fixed electrode plate 12U positioned on the inner side and a fixed electrode plate 12L positioned on the outer side is absorbed. Thus, when the diaphragm 10 is curved, the generation of a force between the electrode plate positioned on the outer side and the electrode plate positioned on the inner side is prevented, and a fixed distance is secured. As a result, in a speaker system 1, the diaphragm 10 in a curved (circular arcuate) shape is arbitrarily formed, the force generated between the electrode plates by the deviation is eliminated, and the distortion of the sound is prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrostatic speaker (condenser speaker) having a variable electrode plate and a fixed electrode plate.

  In general, a speaker called an electrostatic speaker (condenser speaker) is known. This electrostatic speaker has two fixed electrode plates facing each other with a gap, and a conductive sheet-like member (hereinafter referred to as a movable electrode plate) inserted between the electrode plates and fixed at both ends. For use with a diaphragm. The electrostatic speaker having the speaker diaphragm is referred to as a so-called push-pull electrostatic speaker.

The basic sounding mechanism of the electrostatic speaker configured as described above is as follows.
When a predetermined voltage is applied to the fixed electrode plate and the movable electrode plate, a force attracted to one electrode plate side by the generated potential difference acts on the movable electrode plate. The movable electrode plate is fixed at both ends, but has a certain degree of elasticity, so that its central portion is displaced, and as a result, the movable electrode plate bends. When the potential difference is reversed in this state, a reverse force acts on the movable electrode plate, and the movable electrode plate bends in the reverse direction. If such reversal of the potential difference is repeated, the movable electrode plate vibrates. Then, by appropriately applying a voltage to the electrode plate, the vibration state (frequency, amplitude, etc.) of the movable electrode plate can be changed. If the applied voltage value is changed according to the input signal, the movable electrode plate vibrates accordingly, and as a result, a sound corresponding to the input signal is generated from the movable electrode plate. The generated sound is radiated to the outside through a fixed electrode plate having a large number of through-holes and having high sound wave permeability.

  On the other hand, it is known that a flat speaker such as an electrostatic speaker generally has a strong directivity of acoustic characteristics, particularly in a high frequency band, which is stronger than a low frequency band. For this reason, there is a problem in that the audible sound is not uniform depending on the location because the directivity differs depending on the frequency band.

  On the other hand, as a technique for adjusting the directivity of sound, there is an apparatus that combines a radiation surface reflector and a speaker in order to concentrate sound at one point (see, for example, Patent Document 1). In addition, a speaker that can arrange a plurality of speaker units in an array and adjust the timing and gain at which sound is output from each speaker unit so that the sound output from each speaker unit can be emitted so as to be focused. There is an array (see, for example, Patent Document 2).

  However, in the technique described in Patent Document 1, since the shape is determined according to each purpose, for example, it is not possible to collect sound at a single point using only a flat speaker.

  Furthermore, in the stereophonic sound reproduction method described in Patent Document 2, by adjusting the timing and gain at which sound is output from each speaker, the sound is not only emitted so as to be focused, but also has directivity in a single direction. Or can spread the sound. However, in the speaker array, in order to impart directivity to or diffuse the sound to be radiated, a delay circuit and a gain adjustment circuit are provided for each speaker unit constituting the speaker array to control the operation of each circuit. There is a problem that it is necessary and the control becomes complicated.

  Therefore, there has been a technique for adjusting directivity by appropriately bending a flat speaker (speaker unit) (see, for example, Patent Documents 3 and 4).

Japanese Patent Laid-Open No. 04-339494 Japanese Patent No. 3067140 JP 62-234000 A JP 2007-158658 A

  However, in Patent Documents 3 and 4 described above, a flat speaker (speaker unit) can be appropriately bent to adjust the directivity, while by bending a flat plate on which electrode plates are stacked, The electrode plate located on the outside generates tension to be extended and this tension acts inward, and the electrode plate located on the inside generates compressive force to shrink and this compressive force is outward. Acts facing. Then, a pressing force is generated from the fixed electrode plate toward the movable electrode plate, and the distance between the fixed electrode plate and the movable electrode plate becomes a distorted structure depending on the location, and the generated sound may be distorted. .

  Therefore, the present invention provides an electrostatic loudspeaker in which a distorted structure and sound distortion are eliminated with a simple configuration without using a plurality of speaker units, and the radiation direction such as sound collection and diffusion can be adjusted. Objective.

  In order to solve the above-described problems, the configuration of the electrostatic speaker adopted by the present invention is a flexible variable electrode plate that is flexible and vibrates in response to an input signal, and the variable electrode plate. A rectangular fixed electrode plate that is provided facing each other, a buffer material that is provided between the electrode plates and maintains a constant distance between the electrode plates, and an end of the fixed electrode plate Between the electrode plate positioned on the outside and the electrode plate positioned on the inner side when the fixed electrode plate is curved, and is provided on at least one side of the frame. Misalignment absorbing means.

  The said structure WHEREIN: It is preferable that the said shift | offset | difference absorption means is a free end formed in the side which does not curve.

  The said structure WHEREIN: It is preferable that the said shift | offset | difference absorption means is a mechanism formed in the said frame.

  According to the present invention, even when the fixed electrode plate is curved, it is generated between the electrode plates by the displacement absorbing means while keeping the distance between the electrode plates constant by the buffer material provided between the electrode plates. It is possible to absorb the deviation, and to prevent distortion of sound generated from the electrostatic speaker.

Next, embodiments according to the present invention will be described with reference to the drawings.
<< Embodiment >>
<Configuration>
The speaker device according to the present embodiment will be described.
In the present embodiment, for convenience of explanation, the net, casing, electric wiring, and the like on the surface of the speaker device are omitted.
As shown in FIG. 1, the speaker device 1 includes a curvature generating mechanism 2 disposed in a housing (not shown), and a rectangular speaker diaphragm 10 (hereinafter, “ Diaphragm 10 ”).
For convenience of explanation, the longitudinal direction of the diaphragm 10 in a planar state is defined as the X axis, the lateral direction is defined as the Y axis, and the direction orthogonal to each axis is defined as the Z axis.

Bending generation mechanism The bending generation mechanism 2 is inserted into a pin insertion hole 26 drilled in each frame 21 of the diaphragm 10 and can be rotated with respect to the frame 21, and one end of the pin 3. And a guide groove 4 that allows the pin 3 to move in the plane direction of the diaphragm 10, that is, the X-axis direction, and is provided at the other end of the pin 3. And a pin moving device 5 for moving 3 in the X-axis direction.

  As shown in FIG. 2, the pin moving device 5 is provided in a housing (not shown) along the X-axis direction, and has a rectangular case having an opening 6A that opens downward and extends in the length direction. 6, a male screw portion 7 </ b> A is formed on the surface, a drive shaft 7 provided in the case 6 so as to extend in the longitudinal direction in the case 6, and a rotary shaft connected to one end of the drive shaft 7. A motor 9 and sliders 8 and 8 provided on the drive shaft 7 are provided.

The slider 8 is formed in a shape close to the inner shape of the case 6, and the slider 8 is prevented from rotating with respect to the rotation of the drive shaft 7 by contacting the inside of the case 6.
An internal thread portion 8A screwed to the external thread portion 7A of the drive shaft 7 is engraved inside each slider 8, and the other end of the pin 3 is connected to the outside. The shape of the internal thread portion 8A of the slider 8 is a right-hand thread shape or a left-hand thread shape. That is, the right slider 8 is formed with a female screw portion for a right screw (clockwise), and the left slider 8 is formed with a female screw portion for a left screw (counterclockwise).
Further, the male screw portion 7A of the drive shaft 7 is formed for the left screw from the motor 9 side to the vicinity of the central portion in the length direction, and for the right screw from the center to the tip.
Further, the motor 9 rotates the rotating shaft forward and backward according to a command signal input from the outside.

In the bending generation mechanism 2, the state in which the sliders 8 and 8 are spaced apart from each other makes the diaphragm 10 planar (FIG. 5A). When the diaphragm 10 is curved, when a command signal is input to the motor 9 and the rotation shaft is rotated, the drive shaft 7 rotates in the right-handed direction (clockwise). In response to this rotation, the right slider 8 formed with the right-hand female thread 8A moves the X axis to the left, and the left slider 8 formed with the left-hand female thread 8A moves the X-axis. Move to the right.
Thus, by bringing the left and right sliders 8 and 8 closer as shown by the arrow a, both ends of the diaphragm 10 approach each other, and the center of the diaphragm 10 is pushed out in the direction of the arrow b to form a curved shape (see FIG. 5 (b)).

Oscillator diaphragm Next, the diaphragm 10 will be described.
As shown in FIG. 3, the vibration plate 10 includes a movable electrode plate 11, fixed electrode plates 12 </ b> U and 12 </ b> L, insulating spacers 13 </ b> U and 13 </ b> L, and a buffer material 14 that are opposed to each other with the movable electrode plate 11 interposed therebetween.
In the present embodiment, the configuration of the fixed electrode plates 12U and 12L is the same, and the configuration of the insulating spacers 13U and 13L is the same. Therefore, when there is no particular need to distinguish the two, “L” and “U” "Is omitted. In addition, the dimensions of the constituent elements such as the diaphragm and the electrode in the figure are different from the actual dimensions so that the shapes of the constituent elements can be easily understood.

  The movable electrode plate 11 is, for example, a film such as PET (polyethylene terephthalate), PP (polypropylene, polypropylene) or the like obtained by vapor-depositing a metal film or applying a conductive paint, and has a thickness of several μm. The thickness is about tens of μm.

  The fixed electrode plate 12 is formed in a rectangular shape and has conductivity. Further, in the fixed electrode plate 12, a plurality of through holes 12A penetrating from the front surface to the back surface of the fixed electrode plate 12 are provided at predetermined intervals in order to ensure sound transmission.

The insulating spacer 13 is sandwiched between the movable electrode plate 11 and the fixed electrode plate 12 at the corner of the diaphragm 10.
Further, between the movable electrode plate 11 other than the insulating spacer 13 and each fixed electrode plate 12, a buffer material 14 that holds the distance between the electrode plates 11, 12 is disposed. It is formed of a material with high sound transmission.

In the diaphragm 10, the insulating spacer 13L is fixed to the peripheral edge of the fixed electrode plate 12L, and the peripheral edge of the movable electrode plate 11 is fixed to the insulating spacer 13L. The movable electrode plate 11 is fixed to the insulating spacer 13L in a state where no tension is applied. The insulating spacer 13U is fixed on the peripheral edge of the movable electrode plate 11, and the peripheral edge of the fixed electrode plate 12U is fixed on the insulating spacer 13U.
In this configuration, the fixed electrode plates 12U and 12L are fixed to the insulating spacers 13U and 13L so as to face each other with the movable electrode plate 11 interposed therebetween, and the movable electrode plate 11 includes the fixed electrode plate 12U and the fixed electrode plate 12L. In the space, it is supported so that it can vibrate in a direction perpendicular to the fixed electrode plate 12.

Next, the electrical configuration of the diaphragm 10 will be described.
As shown in FIG. 6A, the speaker device 1 includes a transformer 50 and an input unit 60 to which an acoustic signal is input from the outside. The movable electrode plate 11 is connected to a midpoint on the output side of the transformer 50, and the two fixed electrode plates 12 are connected to one end and the other end on the output side of the transformer 50, respectively. In this configuration, when an acoustic signal is input to the input unit 60, a voltage corresponding to the input acoustic signal is applied to the fixed electrode plate 12 and the movable electrode plate 11.

When a potential difference is generated between the fixed electrode plate 12U and the fixed electrode plate 12L due to the applied voltage, an electrostatic force that is attracted to one of the fixed electrode plates 12 acts on the vibration plate 10. That is, the movable electrode plate 11 is displaced (bends) in accordance with the acoustic signal, and vibration is generated by sequentially changing the displacement direction, and sound corresponding to the vibration state (frequency, amplitude, phase) is generated from the movable electrode plate 11. appear. The generated sound passes through at least one fixed electrode plate 12 and is radiated to the outside.
The above is the general configuration of the diaphragm 10.

○ Frame The feature of the speaker device 1 according to the present embodiment is that the vibration plate 10 is curved, and the frames 21 and 21 are provided on two opposite sides that are not curved, and further, one frame 21 absorbs the deviation caused by the curvature. This is in that a deviation absorbing portion 25 is provided.

First, the frames 21 and 21 are positioned on the left and right sides of the diaphragm 10, and the sandwiching portion 22 having a substantially “U” -shaped cross section extending in this side (Y-axis direction) is formed. The clamping part 22 holds the fixed electrode plate 12L, the insulating spacer 13L, the movable electrode plate 11, the insulating spacer 13U, and the fixed electrode plate 12U.
Bolt insertion holes 23 are formed on both sides of the holding portion 22. Then, when the bolt 24 is inserted from one bolt insertion hole 23 into the other bolt insertion hole 23, the bolt 24 is also penetrated into each of the parts. This prevents the electrode plate and the like from falling off the frame 21.

Misalignment absorbing portion Further, when the bolt insertion hole 23 is formed by a long hole 23A extending in the X-axis direction as shown in FIG.
When the diaphragm 10 is curved, the electrode plate located on the inner side and the electrode plate located on the outer side have different radii. Therefore, if the arc length is the same, the opening angle is on the inner side than the outer side. Becomes larger, and the electrode plate positioned inside the electrode plate positioned outside protrudes in the circumferential direction of the arc. Therefore, as shown in FIG. 5B, in the diaphragm 10 that supports one end (left side), a deviation occurs between the outer and inner electrode plates at the other end (right side). Therefore, within the length range of the long hole 23A, the electrode plate positioned on the inner side is moved outward, and the electrode plate positioned on the outer side is moved inward, so that the diaphragm 10 is bent between the fixed electrode plates 12 when bent. Absorbs misalignment.

<Action and effect>
When the diaphragm 10 is bent, as described above, a command signal is input to the motor 9 of the bending mechanism 2 to bend the diaphragm 10 to form the diaphragm 10 in an arc shape. This arc shape can be set by a user or an operator. After the setting is completed, the arc shape is prevented from changing by tightening the bolt 24 of the long hole 23A (deviation absorbing portion 25). The setting of the arc shape may be determined in advance according to the place where the speaker device 1 is installed and the position of the viewer, or may be arbitrarily set.

  If the diaphragm is a flat-plate speaker, it has an oval directivity extending in the direction of sound generation at high frequencies, and may not be suitable depending on the application. Therefore, the speaker device 1 according to the present embodiment is configured such that the ellipse extending in the sound radiation direction is made close to a perfect circle as a directivity by curving the diaphragm 10 by the bending generation mechanism 2 into an arc shape. The device 1 provides a sound with a wide radiation angle and low attenuation of frequency characteristics.

  Further, since the arcuate diaphragm 10 is adjusted by the curvature generating mechanism 2, the diaphragm 10 having an arbitrary radius can be formed and can be deformed according to the needs of the viewer. Further, by bringing the pins 3 close to each other until the pins 3 come into contact with each other by the bending generation mechanism 2, it is also possible to form the diaphragm 10 having a nearly circular shape.

  Further, when the vibration plate 10 is curved, the deviation absorbing portion 25 absorbs the deviation generated between the fixed electrode plate 12U located on the inner side and the fixed electrode plate 12L located on the outer side. Thereby, even when both ends of the diaphragm 10 are supported by the frame 21, there is no action of force due to tension or the like between the outer fixed electrode plate 12L and the inner fixed electrode plate 12U. No force is applied to the movable electrode plate 11 sandwiched between the electrode plates 12 via the buffer material 14. As a result, it is possible to prevent the distortion of sound that has been generated by bending the diaphragm 10 conventionally.

  As described above, in the speaker device 1 according to the present embodiment, the radiation direction such as sound collection / diffusion can be adjusted by forming a flat speaker with high directivity in an arc shape. In addition, sound distortion can be eliminated by absorbing the displacement when the diaphragm 10 is bent with a simple structure.

<< Modification >>
(1)
In the above-described embodiment, the shift absorption when the diaphragm 10 is bent is provided with the shift absorbing portion 25 that supports one end of the two sides that are not bent and absorbs the shift at the other end. However, the present invention is not limited to this, and the shift absorbing portions 25 (long holes) may be formed in the frames 21 at both ends. In this case, as shown in FIG. 5C, the absorbed deviation can be halved when the deviation is absorbed only at one end, and the length of the long hole is also halved.

  Further, as in the diaphragm 10 ′ shown in FIG. 7, a frame 31 may be provided on two curved sides to support each part. In this case, as shown in FIG. 8, in the frame 31, the support portions 31A and the weak portions 31B are alternately formed along the length direction, and each portion is supported by the support portions 31A, and the weak portions 31B vibrate. The plate 10 'is easily bent. Further, long holes are formed at both ends of the frame 31 to form the displacement absorbing portion 32.

  Furthermore, when the two curved sides are supported by the frame 31, the deviation absorbing portion 32 may not be formed, and the two non-curved sides may be absorbed as free ends. Further, the deviation absorbing portion 32 may be formed only at one end portion of each frame 31.

  Further, although the case where the displacement absorbing portion 32 is formed by a long hole has been described, the present invention is not limited to this, and if the displacement between the electrode plates generated when the diaphragm 10 is bent is absorbed, the displacement absorbing portion 32 is not limited to this. The shape is not limited.

(2)
In the above-described embodiment, the bending generation mechanism 2 that bends the diaphragm 10 has been described as forming a curved shape by bringing both ends of the diaphragm 10 closer to each other. However, the present invention is not limited to this, and for example, FIG. The pins 31 extending in the Y-axis direction are formed on both sides of the frame 31 shown in FIG. 1, and the pins on both ends are movable in the Y-axis direction along the guide grooves 4 of the bending mechanism 2 in FIG. The part may be moved back and forth along the Z axis.
Also in such a mechanism, by pushing the center portion of the frame 31 forward along the Z axis, the pins at both ends move inward along the guides, and the diaphragm 10 ′ is curved to form an arc shape. It is formed.

(3)
As shown in FIG. 6B, an electret material 40 may be provided on the movable electrode plate 11 side of the fixed electrode plate 12.
The electret material 40 is a known material obtained by electretizing a polymer such as vinylidene fluoride or Teflon (registered trademark), and is given a surface potential semipermanently. For example, the electret material 40 is formed by immersing or applying a liquid polymer to the fixed electrode plate 12 and drying it.
Since the electret material 40 has a surface potential, a DC voltage corresponding to the surface potential is always applied between the electret member 40 and the DC voltage required in the electric circuit shown in FIG. Can be eliminated.

It is a perspective view which shows the speaker apparatus by embodiment. It is sectional drawing of the pin movement apparatus seen from the arrow II-II direction in FIG. FIG. 3 is a cross-sectional view of the diaphragm viewed from the direction of arrows III-III in FIG. 1. It is a figure which expands and shows the c section in FIG. It is explanatory drawing which shows the plane and curved state of a diaphragm. It is a figure which shows the drive circuit of the speaker apparatus by the embodiment. It is a perspective view which shows the diaphragm by a modification. It is a figure which expands and shows the principal part in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Speaker apparatus, 2 ... Bending generation | occurrence | production mechanism, 3 ... Pin, 4 ... Guide groove, 5 ... Pin moving apparatus, 10 ... Speaker diaphragm (diaphragm), 11 ... Movable electrode plate, 12 ... Fixed electrode plate, 13 ... Insulating spacer, 14 ... Buffer material, 21,31 ... Frame, 22 ... Holding part, 23 ... Bolt through hole, 23A ... Long hole, 25,32 ... Drift absorbing part

Claims (3)

A rectangular variable electrode plate having flexibility and vibrating in response to an input signal;
A fixed electrode plate which is provided facing the variable electrode plate and has flexibility;
A cushioning material provided between the electrode plates and maintaining a constant distance between the electrode plates;
A frame that is provided on at least one side of the end of the fixed electrode plate, and supports each of the electrode plates;
An electrostatic loudspeaker comprising: a gap absorbing means for absorbing a gap generated between an electrode plate located outside and an electrode plate located inside when the fixed electrode plate is bent. The electrostatic speaker according to claim 1,
The displacement absorbing means is a free end formed on a non-curved side. The electrostatic speaker according to claim 1,
The displacement-absorbing means is a mechanism formed in the frame.

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