JP2000078691A - Speaker system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a speaker system that has an excellent acoustic characteristic up to an ultra-high frequency and withstands a high input even at a limited narrow place where the heat dissipation condition is bad. SOLUTION: A piezoelectric speaker 1 is a condenser speaker, has a vibrating body made of a hemispherical electrostriction material such as a piezoelectric ceramic, a surface electrode and a rear electrode as drive electrodes are formed respectively on an outer face and an inner face of the vibrating body, the speaker 1 is fitted to an outer circumference of a voice coil bobbin 103, fixed to the voice coil bobbin 103 and a diaphragm 101 and placed coaxially with the diaphragm 101. The vibrating body of the piezoelectric speaker 1 is polarized in advance in the broadwise direction from, e.g. an inner face (concaved face) to an outer face (projecting face), and an audio signal is applied to the drive electrode to allow the vibrating body to expand/contract along a spherical face and the vibrating body makes aspiring vibration radially from the center of the spherical face. Thus, the entire face of the hemispherical vibrating body of the piezoelectric speaker 1 emits uniformly the acoustic energy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loudspeaker device, and more particularly to a composite loudspeaker device including a dynamic loudspeaker having a cone diaphragm and a piezoelectric loudspeaker using a piezoelectric element.

[0002]

2. Description of the Related Art A cone type speaker, which is a typical example of a dynamic speaker, is shown in FIG. As is well known, a cone-shaped speaker generally has a voice coil bobbin 103 on which a voice coil 102 is wound, having a substantially conical shape (cone shape).
The edge 108 and the damper 109 which are fitted and fixed in the hole at the center of the diaphragm 101
As a result, the diaphragm 101, the voice coil 102, and the voice coil bobbin 103 are elastically supported integrally, whereby the diaphragm 101 is supported at a predetermined stationary position in the central axis X direction of the cone-shaped speaker, and the voice coil 102 and the voice A coil bobbin 103 is spatially supported at a predetermined stationary position within a magnetic gap of a magnetic circuit 107 including a magnet 104, a plate 105, and a pole yoke.

[0003] Both ends of the voice coil 102 are electrically connected to a pair of positive and negative input terminals 110 provided on a frame 112 via lead wires 111, respectively, and audio signals are supplied from the input terminals 110. As a result, the voice coil 102 in the magnetic gap receives an electromagnetic driving force corresponding to the audio signal and is driven back and forth along with the vibration plate 101 in the piston vibration direction. As a result, acoustic energy corresponding to the audio signal is emitted from diaphragm 101.

A center cap 113 formed by a part of a spherical surface is attached to a portion of the diaphragm 101 where a hole at the center of the diaphragm 101 is covered (hereinafter referred to as a center cap portion).
The hole at the center portion of the diaphragm 101 is closed by being arranged substantially coaxially with the hole of No. 01 and fixed to the vicinity of the attachment of the diaphragm 101 or to one end of the voice coil bobbin 103.

Thus, the center cap 113 is
The diaphragm 1 driven by the voice coil 102 has a function of preventing iron powder, dust, dirt, and the like from entering the magnetic gap of the magnetic circuit 107 from outside the speaker device.
By vibrating integrally with 01, it plays a part in radiation of acoustic energy (mainly in a high frequency range) radiated by the cone-shaped speaker. Accordingly, the cone-shaped speaker has a directional characteristic with the central axis X being axially symmetric, and the center of a sound image based on acoustic energy radiated from the diaphragm 101 and the center cap 113 is arranged on the central axis X.

As described above, the cone-shaped speaker has a simple structure, and relatively good acoustic characteristics are easily obtained. Therefore, the cone-shaped speaker is now widely used as a speaker device for audio equipment.

In general, in a cone-shaped speaker, in order to reproduce a low frequency band (low sound range) with a sufficient volume, increasing the aperture (outer diameter) of the diaphragm increases both the mass and the effective area of the diaphragm. It is advantageous. The minimum resonance frequency (f0) can be easily set low by increasing the mass of the diaphragm, and the radiation impedance increases by increasing the effective area of the diaphragm, so that the sound pressure characteristics also become high sensitivity. is there.

On the other hand, in order to reproduce a cone-shaped speaker up to a high frequency band (treble range), a high frequency limit frequency (fH) is required.
Need to be higher. The high frequency limit frequency is represented by the following equation: fH = 1 / 2π ((1 / m1 + 1 / m2) Sh) 1/2. Here, m1 is the mass of the diaphragm, m2 is the mass of the voice coil and the voice coil bobbin, and Sh is the stiffness in the vicinity of the cone of the diaphragm.

As can be seen from this equation, the higher frequency limit becomes higher as the mass of a vibration system such as a diaphragm, a voice coil and a voice coil bobbin becomes smaller. Therefore, the aperture of the diaphragm is made smaller and the voice coil and the voice coil bobbin are made smaller. It is advantageous to reduce the mass of the loudspeaker as much as possible when expanding the reproduction frequency band in the high-frequency range of the cone-shaped speaker.

[0010] More specifically, a diaphragm having a small diameter;
By using a voice coil formed by winding a thin wire with a predetermined resistance value around a small diameter voice coil bobbin, the mass of the vibration system can be reduced and the high frequency limit frequency can be increased, The reproduction frequency band in the treble range is expanded.

As described above, the cone type speaker requires inconsistent conditions for the vibration system when reproducing the low frequency range and when reproducing the high frequency range. It is difficult to reproduce a high frequency range up to the limit frequency with one cone-shaped speaker.

For this reason, conventionally, a large-diameter cone-shaped speaker is used for reproduction of a middle-low range (that is, a range lower than a high range in a range which can be reproduced by a cone-type speaker), and then a diaphragm and a voice are used. The coil and voice coil bobbin use a small-diameter cone-shaped speaker as an auxiliary and connect them with a network filter to form a multi-speaker device, thereby covering a wide reproduction frequency band from the low frequency range to the high frequency range around the audible limit frequency. Was playing.

However, in the above-described multi-speaker device, since the speaker for reproducing the middle and low frequency range and the speaker for reproducing the high frequency range are arranged separately, the center position of the sound image is different between the middle and low frequency range and the high frequency range. As a result, the sound image localization formed by the center position of the sound image obtained by these speakers, the size of the sound image, and the like changes depending on the sound range, and the sound image localization tends to be unnatural.

Therefore, conventionally, when sound image localization is required accurately, a support member 114 and the like are provided on the pole yoke 106 as shown in FIG. By using a coaxial speaker device arranged coaxially with the diaphragm, a wide reproduction frequency band is ensured, and the center position of the sound image and the size of the sound image are adjusted so as not to change much depending on the sound range.

In addition, the coaxial speaker device has an advantage that it is not necessary to separately provide a place for mounting the loudspeaker 115 for reproducing the high-frequency range, and the mounting space for the speaker device is reduced.

[0016]

In recent years, a speaker device has been used in a frame of a door of an automobile or in a housing of a high-quality electronic display device used for a thin personal computer, a television, or the like.
In many cases, one or a plurality of such devices are attached to a limited place in a narrow housing having various forms and used as a part of an audio system. In this case, since the speaker device is arranged at a relatively short distance to the user, in order to obtain accurate sound image localization, better sound characteristics are generally required in a high sound range where the directivity is sharp. Further, in a limited place in such a narrow housing, the speaker device is required to have higher input resistance because the heat radiation efficiency of the voice coil is reduced.

In addition, the sound source used in the speaker device has a high frequency range (ultra high frequency range) of 20 kHz or more, which is much higher than the audible limit frequency, and it is preferable from the viewpoint of music reproduction. The recording frequency band of optical discs is being reviewed, and accordingly, speaker devices are required to reproduce sound up to an ultra-high frequency range.

However, the speaker for reproducing the high-frequency range in the multi-speaker device uses a small-diameter voice coil wound with a small-diameter wire, so that the heat resistance is not very good and the speaker is limited in a narrow housing. When the speaker device is mounted in a place where the speaker device is installed, the heat resistance is further reduced, and the input resistance of the speaker device is further reduced.

In the coaxial speaker device shown in FIG.
The support member 114 is attached to the pole yoke 106 for the purpose of attaching the treble-range sound reproduction speaker 115 coaxially with the diaphragm 101.
And the like need to be separately provided, and the structure near the center cap portion becomes complicated. In the vicinity of the center cap, sound waves mainly radiated from the loudspeaker 115 for high-frequency reproduction and the vicinity of the cone of the diaphragm 101 are supported.
As a result, phase interference, resonance, etc. are caused by the complicated shape of the coaxial speaker device, and as a result, the reproduction frequency characteristic of the coaxial speaker device in the high-frequency range is disturbed, and good acoustic characteristics cannot be obtained.

In the coaxial speaker device shown in FIG.
Since there is no center cap in the hole at the center of the diaphragm 101, iron powder, dust, dirt, and the like are likely to enter the magnetic gap of the magnetic circuit 107, causing abnormal noise and disturbance of the reproduction frequency characteristic during operation of the speaker device. There are cases.

Conventionally, there is a coaxial speaker device having a dustproof cap to prevent this. FIG. 6 is a diagram showing an example thereof. In FIG. 6, the coaxial speaker device is formed by further providing a dustproof cap 116 on the coaxial speaker device shown in FIG.

The dustproof cap 116 is formed of a coarse woven cloth, and is adhered on the diaphragm 101 so as to cover the high-range sound reproduction speaker 115, so that iron dust and dust are contained in the magnetic gap of the magnetic circuit 107. To prevent trash from entering. However, even when the dustproof cap 116 has such an eye roughness that iron powder, dust, dust, and the like do not enter the magnetic gap, the acoustic energy radiated by the high-range sound reproduction speaker 115 is high when the acoustic energy radiated by the speaker 115 passes through the dustproof cap 116. Attenuation of sound energy in the sound range is inevitable. Therefore, if the dustproof cap 116 is provided in the coaxial speaker device, the acoustic characteristics in the high-frequency range are somewhat sacrificed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and provides a speaker device having good acoustic characteristics up to an ultra-high frequency range and having input resistance even in a limited narrow place where heat radiation conditions are poor. The purpose is to provide.

[0024]

According to the first aspect of the present invention,
The speaker device includes a dynamic speaker having a cone diaphragm and a piezoelectric speaker disposed in a center cap portion of the dynamic speaker.

According to the first aspect of the present invention, the dynamic speaker and the piezoelectric speaker are arranged coaxially, and the central axes of the directional characteristics of the respective speakers are aligned coaxially. The center position and the size of the sound image do not change much depending on the sound range up to the super-high range, and accurate sound image localization can be obtained, so that the acoustic characteristics up to the super-high range are improved. Further, by using the piezoelectric speaker, the input resistance of the speaker device does not decrease even when the speaker device is mounted in a limited narrow place where heat radiation conditions are poor.
In addition, since the piezoelectric speaker closes the hole in the center of the diaphragm, iron powder, dust, dust, and the like do not enter the magnetic gap of the magnetic circuit, and the acoustic characteristics up to an ultra-high frequency range are improved.

According to a second aspect of the present invention, in the speaker device according to the first aspect, the piezoelectric speaker is constituted by a dome-shaped or hemispherical-shaped piezoelectric element.

According to the second aspect of the present invention, the piezoelectric speaker uniformly radiates acoustic energy from the entire surface of the dome-shaped or hemispherical vibrating body, so that the speaker device comprises a coaxially arranged dynamic speaker and a piezoelectric speaker. A wide directional characteristic can be obtained for each sound range from a low range to a super-high range by the type speaker, and the sound characteristics become good. As a result, an audio system using this speaker device can easily control the sound field.

According to a third aspect of the present invention, in the speaker device according to the first or second aspect, an equalizer is arranged in front of the piezoelectric speaker. According to the third aspect of the invention, the reproduction frequency characteristic of the piezoelectric speaker mainly in the high-frequency range is smoothly expanded to the ultra-high frequency range, and the directional characteristic in the frequency range up to the ultra-high frequency range has a desired width. It can be adjusted, and the sound characteristics up to the ultra-high frequency range become good. As a result, an audio system using this speaker device can easily control the sound field.

According to a fourth aspect of the present invention, in the speaker device of the first aspect, an audio signal in a high frequency range is supplied to the piezoelectric speaker. According to the fourth aspect of the present invention, since the audio signal in the high frequency range is acoustically converted by the piezoelectric speaker, which is a capacitive low impedance element, a sound pressure sensitivity proportional to the frequency of the audio signal is obtained in the high frequency range. And the sound characteristics up to the super-high frequency range are improved.

[0030]

Next, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing the structure of the speaker device according to the first embodiment of the present invention. Note that in FIG.
The same reference numerals are given to the same components as
Since the description is redundant, it is omitted here.

The speaker device shown in FIG. 1 is the same as the conventional dynamic speaker shown in FIG. 4 except that the piezoelectric speaker 1 is arranged at the center cap portion of the dynamic speaker in place of the center cap 113. It is.

The piezoelectric speaker 1 is a capacitive speaker, for example, has a vibrating body made of a hemispherical electrostrictive material made of, for example, piezoelectric ceramics, and outer and inner surfaces of the vibrating body serve as driving electrodes for the vibrating body. A front surface electrode and a back surface electrode are respectively formed, fitted to the outer peripheral edge of the voice coil bobbin 103, fixed to the voice coil bobbin 103 and the diaphragm 101, and arranged coaxially with the diaphragm 101.

The vibrating body of the piezoelectric speaker 1 is polarized in advance in the thickness direction, for example, from the inner surface (concave surface) side to the outer surface (convex surface) side. Expands and contracts along the spherical surface, and respirates and vibrates radially from the center of the spherical surface. Thus, the piezoelectric speaker 1 can uniformly radiate acoustic energy from the entire surface of the hemispherical vibrator.

In the piezoelectric speaker 1, lead wires (not shown) are respectively led out from both electrodes along the diaphragm 101, and input terminals are connected via a high-tone network filter (not shown) including a capacitor. Connected to 110. Therefore, the piezoelectric speaker 1 is connected in parallel with the dynamic speaker via the network filter for the high frequency range.

When an audio signal is supplied from the input terminal 110, the audio signal is directly supplied to a dynamic speaker, and acoustic energy corresponding to the audio signal is radiated from the diaphragm 101. Also, the input terminal 110
When an audio signal is supplied from the
Is supplied with a high-frequency audio signal via a network filter, and acoustic energy corresponding to the high-frequency audio signal is radiated from the hemispherical vibrator.

As described above, since the piezoelectric speaker 1 is disposed in the center cap of the dynamic speaker, the central axes of the directional characteristics of the piezoelectric speaker 1 and the dynamic speaker are aligned coaxially. The center position of the sound image and the size of the sound image due to the sound reproduction of the speaker device do not change much in the sound range up to the super-high frequency range, so that accurate sound image localization can be obtained, so that the acoustic characteristics up to the super-high frequency range are improved. .

Further, since the piezoelectric speaker 1 uniformly radiates acoustic energy from the entire surface of the hemispherical vibrating body, the directional characteristics in the high frequency range are uniformly widened. Therefore,
The loudspeaker device can obtain a wide directional characteristic uniformly for each sound range from the low range to the very high range by using a dynamic speaker and a piezoelectric type speaker arranged coaxially with the center axis X, and the sound up to the very high range can be obtained. The characteristics are good. As a result, an audio system using this speaker device can easily control the sound field.

The piezoelectric loudspeaker 1 is a capacitive low-impedance element, and a sound pressure proportional to the frequency of the high-frequency audio signal supplied to the piezoelectric loudspeaker 1 is obtained in the reproduction frequency characteristic. Further, since the piezoelectric speaker 1 does not have a voice coil, it does not generate much heat when driven.

Therefore, even if the speaker device is installed in a narrow housing having poor heat radiation conditions, the input resistance as in a conventional high-range sound reproduction speaker does not decrease. Therefore, the sound can be reproduced with a sufficient volume up to an ultra-high frequency range, and the acoustic characteristics of the speaker device are improved.

Further, the piezoelectric speaker 1 has a diaphragm 10
Since the hole at the center portion of the diaphragm 101 is closed by being disposed in the center cap portion, it is possible to prevent iron powder, dust, dust and the like from entering the magnetic gap of the magnetic circuit 107 from outside the speaker device. .

Therefore, when the speaker device is driven, abnormal noise due to iron powder, dust, or dust is not generated during the operation of the speaker, and the reproduction frequency characteristics are not disturbed, so that good acoustic characteristics up to an ultra-high range can be obtained. Can be

Next, a second embodiment will be described.
2A and 2B are diagrams illustrating a structure of a speaker device according to a second embodiment of the present invention, wherein FIG. 2A is a diagram viewed from the front of the speaker device, and FIG. 2B is a diagram viewed from a cross section. . In FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals, and the detailed description thereof will not be repeated here.

The speaker device shown in FIG. 2 includes the dynamic speaker shown in FIG. 1, a piezoelectric speaker 2 disposed in a center cap portion of the dynamic speaker, and an equalizer 3.

The piezoelectric loudspeaker 2 is different from the piezoelectric loudspeaker 1 in the outer shape of the vibrator and the electrodes, but the other configuration and operation principle are the same as those of the piezoelectric loudspeaker 1. The vibrating body of the piezoelectric speaker 2 is formed by a part of a spherical shell having a predetermined spherical surface, and a front surface electrode and a back surface electrode as driving electrodes of the vibrating body are provided on an outer surface (convex surface) side and an inner surface (concave surface) side of the vibrator. Each is formed.

In the piezoelectric speaker 2, similarly to the piezoelectric speaker 1 in the first embodiment, a lead wire (not shown) is once led out from both electrodes along the diaphragm 101, and includes a high-frequency range including a capacitor. Connected to the input terminal 110 via a network filter (not shown). Therefore, the piezoelectric speaker 2 is connected in parallel with the dynamic speaker via the network filter for the high frequency range.

Further, in the speaker device, an equalizer 3 is arranged in front of the piezoelectric speaker 2 as shown in FIG. The equalizer 3 includes, for example, a spherical shell 3a made of a metal plate or a synthetic resin plate having an inner surface formed corresponding to the outer surface of the spherical shell of the vibrating body of the piezoelectric speaker 2, and the spherical shell 3a.
One or a plurality of correction holes 3b are opened in a central portion or a peripheral portion of the device. A plurality of holding portions 3c are formed radially integrally with the spherical shell 3a around the spherical shell 3a.

In the equalizer 3, one end of each holding portion 3 c is attached to the frame 112 so that the spherical shell 3 a is arranged in front of the piezoelectric speaker 2. As a result, the spherical shell 3a of the equalizer 3 moves the diaphragm 101 around the central axis X.
It is arranged coaxially with the piezoelectric speaker 2 in front of the piezoelectric speaker 2 arranged coaxially.

The equalizer 3 is an acoustic equalizer for adjusting the acoustic energy radiated from the convex surface of the vibrating body of the piezoelectric speaker 2 and the vicinity of the cone of the diaphragm 101, and has an inner surface of the spherical shell 3a. , The distance between the spherical shell 3a and the vibrating body of the piezoelectric speaker 2 and the position of the correction hole 3b,
By appropriately setting the size, shape, etc., the interference of sound waves radiated from each part of the convex surface of the vibrating body of the piezoelectric speaker 2 and each part near the attachment of the cone of the diaphragm 101 is controlled, and mainly the treble range of the speaker device is controlled. , The reproduction frequency characteristic can be smoothly expanded to a super-high frequency range, and the directional characteristic can be adjusted to a desired width in a frequency band up to the super-high frequency range. Therefore, the acoustic characteristics of the speaker device up to an ultra-high frequency range are improved, and as a result, the sound field control is facilitated in an audio system using the speaker device.

In the first and second embodiments, the vibrating body of the piezoelectric speaker is formed by a part of a spherical shell. However, the vibrating body of the piezoelectric speaker in the present invention is not limited to this.
Any dome shape having a curved surface protruding forward of the piezoelectric speaker may be used.

In this embodiment, the equalizer comprises a spherical shell 3a having a correction hole 3b and an equalizer 3 having a holder 3c. One end of each holder 3c is attached to the frame 112. Although the spherical shell portion 3a is arranged in front of the piezoelectric speaker 2, the equalizer in the present invention is not limited to this, and may be constituted by, for example, the equalizer shown in the other embodiment of FIG.

FIGS. 3A and 3B are views showing the structure of a speaker device according to another embodiment of the present invention, wherein FIG. 3A is a view from the front of the speaker device, and FIG. It is. In FIG. 3, equalizer 4 is equalizer 3.
It has a spherical shell portion 4a and a correction hole 4b configured in the same manner as described above.

As shown in FIG. 3, the equalizer 4 is mounted directly on the diaphragm 101 so that the spherical shell 4 a is disposed in front of the piezoelectric speaker 2. As a result, the spherical shell 4a of the equalizer 4 moves the diaphragm 101 around the central axis X.
It is arranged coaxially with the piezoelectric speaker 2 in front of the piezoelectric speaker 2 arranged coaxially.

The equalizer 4 is an acoustic equalizer for adjusting the acoustic energy radiated from the convex surface of the vibrating body of the piezoelectric speaker 2 and the vicinity of the cone of the diaphragm 101 in the same manner as the equalizer 3. The curvature of the inner surface of the shell 4a,
The distance between the spherical shell portion 4a and the vibrating body of the piezoelectric speaker 2 and the equalizer 4 of the correction hole 4b are, like the equalizer 3, near the convex surface of the vibrating body of the piezoelectric speaker 2 and the attachment of the cone of the diaphragm 101. Is a sound equalizer for adjusting the acoustic energy radiated from the antenna, the curvature of the inner surface of the spherical shell 4a, the distance between the spherical shell 4a and the vibrating body of the piezoelectric speaker 2,
Also, by appropriately setting the position, size, shape, and the like of the correction hole 4b, interference of sound waves radiated from each part of the convex surface of the vibrating body of the piezoelectric speaker 2 and each part near the cone of the diaphragm 101 is controlled. I do.

In this case, since the equalizer 4 is directly attached to the direct diaphragm 101 to which the piezoelectric speaker 2 is fixed, when the diaphragm 101 vibrates with the piezoelectric speaker 2 back and forth along the X-axis, The equalizer 4 and the piezoelectric speaker 2 are kept at a constant distance from each other while the diaphragm 10
It vibrates according to the vibration of 1.

Therefore, the piezoelectric speaker 2 and the equalizer 4 do not collide with each other even when the diaphragm 101 largely vibrates back and forth along the X-axis to reproduce the bass range with a sufficient volume. For this reason, the spherical shell 4a of the equalizer 4
The distance between the piezoelectric speaker 2 and the vibrator of the piezoelectric speaker 2 can be set extremely small. The smaller this interval is, the easier it is to control the interference between sound waves having shorter wavelengths, smoothly expanding the reproduction frequency characteristics in the high-frequency range of the speaker device to the ultra-high frequency range, and at the same time directing in the frequency band up to the ultra-high frequency range. The characteristics can be adjusted to characteristics of a desired size.

In each of the above-described embodiments, the piezoelectric speaker is fitted to the outer peripheral edge of the voice coil bobbin 103, fixed to the voice coil bobbin 103 and the diaphragm 101, and arranged coaxially with the diaphragm 101. Configured
However, the present invention is not limited to this. The voice coil bobbin 103 may be directly fixed to the voice coil bobbin 103, or a cylindrical member different from the voice coil bobbin 103 may be provided inside the voice coil bobbin 103. The piezoelectric speaker may be attached to the cylindrical member so as to be coaxially arranged with the diaphragm 101.

The shape of the vibrating body of the piezoelectric speaker is
In the first embodiment, the vibrator of the piezoelectric speaker according to the present invention is not limited to a hemispherical shape, and is formed by a part of a spherical shell having a predetermined spherical surface in the second embodiment.
Any dome shape having a curved surface protruding forward of the piezoelectric speaker may be used.

[0058]

According to the present invention, the dynamic speaker and the piezoelectric speaker are arranged coaxially and the central axes of the directional characteristics of the respective speakers are aligned coaxially. As a result, the center of the sound image by the sound reproduction of the speaker device is obtained. Since the position and the size of the sound image do not change much depending on the sound range up to the super-high frequency range, an accurate sound image localization can be obtained, so that the acoustic characteristics up to the ultra-high frequency range are improved.

Also, by using a piezoelectric speaker,
Even if the speaker device is mounted in a limited narrow place where heat radiation conditions are poor, the input resistance of the speaker device does not deteriorate. In addition, since the piezoelectric speaker closes the hole at the center of the diaphragm, iron powder, dust, dust, and the like do not enter the magnetic gap of the magnetic circuit, and the acoustic characteristics are improved up to an ultra-high range.

Further, by forming the piezoelectric speaker into a dome shape or a hemispherical shape, acoustic energy is uniformly radiated from the entire surface of the vibrating body of the piezoelectric speaker.
The speaker device can obtain a wide directional characteristic for each sound range from a low frequency range to a super-high frequency range by a dynamic speaker and a piezoelectric type speaker arranged coaxially. As a result, an audio system using this speaker device cannot be used. The sound field control becomes easy.

Further, by disposing an equalizer in front of the piezoelectric speaker, the reproduction frequency characteristic of the piezoelectric speaker mainly in the high-frequency range can be smoothly expanded to the ultra-high frequency range, and the directional characteristic can be increased in the frequency band up to the ultra-high frequency range. Can be adjusted to characteristics of a desired size, and the acoustic characteristics up to an ultra-high frequency range are improved. As a result, an audio system using this speaker device can easily control the sound field.

When a high-range audio signal is supplied to the piezoelectric speaker, the high-range audio signal is acoustically converted by the piezoelectric speaker, which is a capacitive low-impedance element. Sound pressure sensitivity proportional to the frequency of the signal can be obtained,
The sound characteristics up to the very high frequency range are good.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of a speaker device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a structure of a speaker device according to a second embodiment of the present invention.

FIG. 3 is a diagram illustrating a structure of a speaker device according to another embodiment of the present invention.

FIG. 4 is a diagram showing a conventional cone-shaped speaker.

FIG. 5 is a diagram showing a conventional coaxial speaker device.

FIG. 6 is a diagram showing a conventional coaxial speaker device.

[Explanation of symbols]

 1, 2,... Piezo-electric speaker 3, 4,... Equalizer 3a, 4a... Spherical shell 3b, 4b... Correction hole 3c. Vibration plate 103 Voice coil bobbin 112 Frame

Claims (4)

[Claims] 1. A speaker device comprising: a dynamic speaker having a cone diaphragm; and a piezoelectric speaker disposed at a center cap portion of the dynamic speaker. 2. The speaker device according to claim 1, wherein the piezoelectric speaker is constituted by a dome-shaped or hemispherical-shaped piezoelectric element. 3. The speaker device according to claim 1, wherein an equalizer is disposed in front of the piezoelectric speaker. 4. The speaker device according to claim 1, wherein a high-frequency audio signal is supplied to the piezoelectric speaker.