JP2007318554A - Electrostatic speaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve durability with respect to power supply to a diaphragm without giving an adverse effect to the vibrating state of the diaphragm. <P>SOLUTION: This electrostatic speaker 1 has electrodes 20 and the diaphragm 10 displaceable by electrostatic power, wherein the diaphragm has a plurality of slits 102 arranged along the boundary B of its circumferential part and a power supply part provided outside the slits. According to such a configuration, vibrations suitable to the occurrence of an acoustic wave can be obtained in an inner area Rv, and on the other hand, strength suitable to the power supply is ensured in an outer side area Re. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a structure of an electrostatic speaker.

A speaker called an electrostatic speaker (condenser speaker) is known. Since the structure of the electrostatic speaker is relatively simple, it has been attracting attention because it can be designed to be lightweight and compact, and the theoretical handling is also simple. An electrostatic loudspeaker typically includes two parallel flat electrodes facing each other across a gap, and a conductive sheet-like member (hereinafter referred to as “inserted between the electrodes” supported by a housing or the like). , Called a diaphragm or diaphragm) (so-called push-pull type). When a predetermined bias voltage is applied to the diaphragm and the voltage applied to both electrodes is changed, the electrostatic force acting on the diaphragm changes, and thereby the diaphragm is displaced. Since the diaphragm usually has its ridges and sides fixed to the casing, the displacement becomes larger at the center portion, and the entire diaphragm is bent. If the voltage applied to the electrodes is changed according to the input musical sound signal, the diaphragm repeats displacement (that is, vibrates) accordingly, and an acoustic wave corresponding to the input musical sound signal is generated from the diaphragm. The generated musical sound is emitted to the outside of the speaker through, for example, a hole formed in the metal plate electrode (see Non-Patent Document 1). Here, in order to supply voltage to the diaphragm, a method in which a clip terminal attached to the tip of the power cable is engaged with the edge of the diaphragm or a method in which the edge of the power cable and the diaphragm is soldered is used. . Alternatively, for example, there is a method in which a conductive tape is attached to the edge of one side of the diaphragm, the tape is routed outside an electrode or a speaker housing, and the tape and the power cable are joined with solder, a clip, or the like.
Masanori Okazaki, Yosuke Kimura, Yoshiyoshi Yanagi, Yasuhiro Oikawa, Yoshio Yamazaki, “Condenser Speaker with a Vibrating Piston in All Bands and its Applications”, Proceedings of the Acoustical Society of Japan p.563-564, September 2004

  However, since the thickness of the diaphragm that is usually used is several to several tens of microns, the mechanical strength is generally low. For example, corrosion or peeling due to secular change may occur at the joint between the diaphragm and the power cable (hereinafter referred to as a power feeding unit), and disconnection may occur. Moreover, even if it does not go to a disconnection, the characteristic (sound pressure, sound quality, etc.) of the sound wave generated by a diaphragm will fall by the contact resistance value of an electric power feeding part rising. In addition, since a force (elastic stress) is applied to the diaphragm due to its own vibration, the diaphragm may be damaged from a low-strength power feeding unit during continuous use. Here, it is conceivable to increase the thickness of the diaphragm in order to ensure the mechanical strength of the diaphragm, but if the thickness changes, the vibration state also changes, which adversely affects the acoustic characteristics such as sound quality and sound pressure. There is a fear. In addition, when using a conductive tape or the like, the force applied to the power feeding part can be reduced to some extent, but the thickness of the diaphragm is different between the part where the tape is attached and the part where the tape is not. There may be an adverse effect on the vibration state of the diaphragm, and a deterioration in sound quality due to an increase in resistance value caused by handling the conductive tape may be considered.

As described above, in the related art, it is impossible to apply a voltage to the diaphragm while maintaining the durability of the power feeding unit without adversely affecting the vibration state of the diaphragm.
Accordingly, an object of the present invention is to provide a diaphragm capable of applying a voltage while maintaining the strength of the contact portion without adversely affecting the vibration state of the diaphragm, and a power feeding method to the diaphragm. .

  In order to solve the above-mentioned problems, in one aspect, the present invention provides an electrostatic speaker having a planar electrode and a diaphragm that is provided opposite to the planar electrode and that can be displaced by an electrostatic force. Has a plurality of openings formed at a predetermined interval on the peripheral edge thereof, and a power feeding part provided outside the openings.

  In another aspect, the present invention provides an electrostatic loudspeaker having a planar electrode and a diaphragm that is disposed opposite to the planar electrode and can be displaced by an electrostatic force, and the diaphragm is at least one closed A plurality of openings formed at predetermined intervals along a boundary defining the region, and a power feeding unit provided outside the region.

  According to the present invention, since the opening is formed in a predetermined region on the diaphragm, vibration suitable for generation of acoustic waves can be realized in the inner region with the opening as a boundary, while on the outer side thereof The strength suitable for providing the power feeding unit is ensured.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of a schematic structure of an electrostatic speaker 1 according to one embodiment of the present invention. As shown in the figure, the electrostatic speaker 1 is generally composed of a diaphragm 10 and two planar electrodes (hereinafter simply referred to as electrodes) 20 facing the diaphragm 10.

  The electrode 20 has a conductivity such as a punched metal having a thickness k and a side length w, a punched metal in which holes H are formed in a metal plate, a non-coated sputtered nonwoven fabric, a non-woven fabric coated with a conductive paint, and the like. It is made of a material having high sound wave permeability and is fixed to a casing (not shown) of the electrostatic speaker 1. At this time, it arrange | positions so that the distance d from the diaphragm 10 to both the electrodes 20 may become equal. In other words, the position just between the opposing electrodes is a fixed position of the diaphragm 10 (more precisely, the diaphragm 10 in a non-displacement state, which is a state when no signal is input).

  In addition, the electrostatic speaker 1 includes a power source (not shown) so that a desired voltage can be applied to each electrode 20 and a bias voltage can be applied to the diaphragm 10. Since a conventional technique can be adopted as a method for supplying power to the electrode 20, illustration and description thereof are omitted. In power feeding on the diaphragm 10, power feeding is performed from a power cord connected to a power source via a power feeding section 101 provided on the diaphragm 10 as shown in FIG. Specifically, the power cord and the vibration plate 10 may be joined by soldering in the power supply unit 101, or a highly rigid metal plate is sandwiched from both surfaces of the vibration plate 10 in the vicinity of the power supply unit 101. The power cord 30 may be screwed to the diaphragm 10. The electrostatic speaker 1 further includes an input unit for inputting a sound signal from the outside, and causes the diaphragm 10 to vibrate according to the sound signal by changing the value of the applied voltage according to the sound signal. Can be done. A sound wave generated by the vibration of the diaphragm 10 passes through at least one electrode 20 and is emitted to the outside of the speaker.

  The diaphragm 10 is obtained by depositing a metal film on a film such as PET (polyethylene terephthalate) or PP (polypropylene), or applying a conductive paint. It is a conductive plate-like (film-like) member of about several tens of microns. The diaphragm 10 is a fixing means (not shown) formed of an insulating material such as vinyl chloride, acrylic (methyl methacrylate), rubber or the like, in a state where a predetermined tension is applied to the diaphragm 10, for example, One side of the edge is supported by a casing (not shown) of the electrostatic speaker 1. The diaphragm 10 is formed with a plurality of openings (slits 102). Details will be described below.

  FIG. 2 is a view for explaining the detailed structure of the diaphragm 10. As shown in the figure, rectangular holes (slits 102) having lengths dw and ds are arranged at regular intervals t in the peripheral portion of the diaphragm 10. The diaphragm allows the diaphragm to define an inner region Rv and an outer region Re. In other words, a boundary B represented by a dotted line in the drawing is defined in the diaphragm 10, and the boundary B separating the inner closed region Rv and the outer region Re (that is, the peripheral portion of the diaphragm 10). A slit 102 is arranged along the line. A power feeding unit 101 is provided at an arbitrary location in the region Re.

  When the plurality of slits 102 are arranged along the boundary B in this manner, the strength (rigidity) of the portion of the region Rv inside the boundary B is reduced, while the strength of the portion of the outer region Re is hardly reduced. Thus, in the present invention, the strength (rigidity) of one diaphragm 10 is partially changed. In the example of the figure, so to speak, the inner part (region Rv) of the diaphragm 10 is suspended by the “outer frame” (region Re) of the diaphragm 10 through the diaphragm part between the slits with the boundary B as the boundary. It will be in such a state. As a result, the region Rv becomes easier to vibrate than the region Re. For this reason, the sound pressure and the sound quality of the acoustic wave generated by the region Rv can be improved.

  On the other hand, since the power supply unit 101 is provided in the region Re where the original rigidity is maintained, problems such as deterioration of the power supply unit do not occur. Here, if the boundary B is sufficiently set at the peripheral edge (in other words, if the area of the region Rv is sufficiently larger than the area of the region Re), the acoustic wave is substantially generated in the region. Since it can be said that it is Rv, in order to raise the rigidity of the electric power feeding part 101, it is also possible to reinforce the electric power feeding part 101 with a metal plate etc., for example. FIGS. 3A and 3B are an enlarged view of an example of the power feeding unit 101 and a cross-sectional view thereof. As shown in FIG. 3 (b), the power supply unit 101 sandwiches the diaphragm 10 from both sides, and screws the two reinforcing aluminum plates 103 with screw holes, the aluminum plate 103, and the power cable. And a screw 104. As a result of such reinforcement, even if the vibration in the region Re is suppressed, the influence hardly affects the vibration state of the region Rv due to the slits, and therefore the adverse effect on the sound pressure and sound quality of the diaphragm 10 as a whole is substantial. Can be ignored.

  In forming the slit 102, the simplest is to prepare a single diaphragm and form a hole having the same shape. As described above, according to the present invention, it is possible to simultaneously improve the sound pressure and sound quality and the durability of the power feeding unit by performing simple processing on one diaphragm.

  In addition, the arrangement | positioning method of a slit is not restricted to the example shown in FIG. The shape, size, area, number of slits, distance between adjacent slits, and slit positions can be appropriately changed. Since there is a relationship between the rigidity of the diaphragm and the characteristics (output, frequency characteristics, etc.) of the acoustic waves generated there, it is possible to determine the arrangement of the slits according to the desired acoustic characteristics. For example, if the area of the slit is reduced and the interval is increased (rough), the restoring force against vibration in the region Rv is increased and the amplitude of the diaphragm is decreased, so that the output level of the acoustic wave is suppressed. On the contrary, when the area of the slit is increased and the interval is decreased (dense), the restoring force is decreased and the amplitude of the diaphragm is increased, so that a high output can be realized. Further, by reducing the area of the region Rv, the high frequency region can be dominantly or selectively output. Conversely, if the area of the region Rv is increased, a wide entire frequency band including the bass region can be output. Thus, the area and the number of regions Re can be set as appropriate according to a desired frequency band. Further, the interval between the slits is not necessarily constant.

  FIG. 4 shows an example in which a plurality of slits 102 are arranged so that two regions Rv1 and Rv2 having different areas are formed on the vibration plate 10. In this example, the middle and high tones are predominantly output from the region Rv1, while the entire sound region is output from the region Rv2. In addition, although the electric power feeding part 101 is provided in the outer side of both area | regions, it abbreviate | omits about illustration.

  Further, as shown in FIG. 5, the slits 102 may be arranged so that a plurality of regions (Rv3 to Rv6) having the same area are continuously formed. In this manner, by forming a set (array) of vibration regions on the diaphragm 10, it is possible to emit acoustic waves having desired frequency characteristics and directivity characteristics. Although the power supply unit 101 is provided outside the array region, the illustration thereof is omitted.

  In the above-described embodiment, the push-pull type electrostatic speaker 1 using a pair of counter electrodes using the diaphragm 10 of the present invention has been described, but the single-type static speaker using the diaphragm 10 is described. Of course, an electric speaker may be constructed. Further, the power supply unit 101 may be provided at a plurality of locations as long as it is within the region Re instead of at one location. Further, instead of forming a through hole such as the slit 102, a position corresponding to the arrangement position of the slit 102 may be formed of a material having a lower strength (lower rigidity) than other regions. In short, it is only necessary that a relatively low rigidity region suitable for generation of acoustic waves and a relatively high rigidity region suitable for formation of the power feeding portion are formed on the diaphragm 10.

1 is an external perspective view showing a schematic configuration of an electrostatic speaker 1 according to the present invention. 3 is a diagram for explaining a structure of a diaphragm 10. FIG. It is the figure which expanded the electric power feeding part. 3 is a cross-sectional view of a power feeding unit 101. FIG. It is a figure for demonstrating the structure of 10 A of diaphragms. It is a figure for demonstrating the structure of the diaphragm 10B.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electrostatic speaker, 10, 10A, 10B ... Diaphragm, 20 ... Electrode, 30 ... Power cord, 101 ... Feeding part, 102 ... Slit, 103 ... Aluminum plate, 104 ... screws.

Claims (3)

An electrostatic loudspeaker having a planar electrode and a diaphragm that is provided opposite to the planar electrode and can be displaced by an electrostatic force,
The diaphragm is
A plurality of openings formed at predetermined intervals along the peripheral edge;
An electrostatic speaker, comprising: a power feeding unit provided outside the opening. An electrostatic loudspeaker having a planar electrode and a diaphragm that is provided opposite to the planar electrode and can be displaced by an electrostatic force,
The diaphragm is
At least one closed area;
A plurality of openings formed at predetermined intervals along a boundary defining the region;
An electrostatic speaker comprising: a power feeding portion provided outside the region. The electrostatic speaker according to claim 1, wherein each of the plurality of openings is a slit having the same shape.

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