JP3809917B2 - Piezoelectric speaker - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piezoelectric speaker driven by electromagnetic induction used in a composite speaker.
[0002]
[Prior art]
As a piezoelectric speaker that is driven by electromagnetic induction used in a conventional composite speaker, the diaphragm has a combination of a cone type and a dome type, and the outer periphery of the dome part and the piezoelectric element are joined so far. Has also been announced.
These conventional examples will be described with reference to FIG. FIG. 6 shows a built-in state of the composite speaker, in which 15 is a piezoelectric speaker driven by electromagnetic induction used as a tweeter of the composite speaker, and 20 is a woofer of the composite speaker. The tweeter 15 includes a diaphragm 19 having a combination of a cone type and a dome shape attached to the frame 6, an induction coil 7 for electromagnetic coupling arranged at the lower part of the frame 6, and an outer periphery of the dome portion of the diaphragm 19. The piezoelectric element 5 is joined.
[0003]
The woofer 20 includes a vibration system including a diaphragm 21, a voice coil 23, and a damper 24, a magnetic circuit including a magnet 25, a top plate 26, a center pole 27, a frame 22, and the like.
The tweeter 15 is placed on the center pole 27 of the woofer 20, and the induction coil 7 is fixed in the vicinity of the voice coil 23. An induced voltage is generated in the induction coil 7 by a voltage generated in the voice coil 23 by the audio current, and this induced voltage is applied to the piezoelectric element 5.
[0004]
[Problems to be solved by the invention]
However, the diaphragm of a piezoelectric speaker that is driven by electromagnetic induction used in a conventional composite speaker is used to increase the exchange efficiency of piezoelectric elements, but has a narrow reproduction frequency band and flat frequency characteristics. There was a problem.
[0005]
The present invention has been made in view of these points, and an object of the present invention is to provide a piezoelectric speaker capable of obtaining a flat frequency characteristic and efficiently reproducing a wide band.
[0006]
[Means for Solving the Problems]
Therefore, in the piezoelectric speaker according to the present invention, in order to eliminate the disadvantages in the above-described conventional example, the diaphragm is formed in a rectangular shape including a plurality of parallel semi-cylindrical surfaces. In addition, the piezoelectric element is supported on the diaphragm by a line or point bonding on a concave portion that is a boundary of the semi-cylindrical surface of the diaphragm. As a result, in the vicinity of the junction between the diaphragm and the piezoelectric element, the rigidity in the vibration direction is large and the high frequency resonance frequency is increased, so that the reproduction frequency band can be widened.
Further, since the diaphragm of this piezoelectric speaker is square when viewed from the direction of the sound wave, the same outer dimensions have a larger vibration area and thus have a higher efficiency than the conventional circular diaphragm speaker.
In addition, since the diaphragm has a semi-cylindrical surface shape, the slope angle of the diaphragm continuously changes from the joint surface to the top of the piezoelectric element, and the longitudinal direction of the semi-cylindrical surface vibrates in the same phase. Compared with the above case, reproduction at a high level can be continuously performed in the reproduction frequency band, and the characteristics are flat.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The piezoelectric speaker according to the first aspect of the present invention includes a diaphragm 1 attached to a frame 6, an induction coil 7 for electromagnetic coupling disposed at a lower portion of the frame 6, and a piezoelectric element 5 supported by the diaphragm 1. a piezoelectric speaker is driven by an electromagnetic induction comprised of the diaphragm 1, as viewed plurality of semi-cylindrical surface 1a which is parallel and adjacent to each other, from 1b · · · in the direction of growth Rutotomoni waves square None, and mounted to the frame 6 at its outer periphery 1s, 1s, the piezoelectric element 5, a plurality of semi-cylindrical surface 1a of the diaphragm 1 and the frame 6 in a non-contact state, mutual 1b · · · It is characterized in that it is supported on the diaphragm 1 by line bonding at the recess 1r at a position adjacent to the diaphragm 1r.
[0008]
Also, pressure electrostatic speaker of the present invention according to claim 2, a diaphragm 3 attached to the frame 6, the induction coil 7 for electromagnetic coupling which is disposed below the frame 6, which is supported on the vibrating plate 3 piezoelectric a piezoelectric speaker is driven by electromagnetic induction comprising a device 5 which, the vibrating plate 3 has a plurality of semi-cylindrical surface 3a which is parallel and adjacent to each other, from the direction of formation Rutotomoni waves from 3b · · · The piezoelectric element 5 is attached to the frame 6 at its outer periphery 3s, 3s, and has a plurality of semi-cylindrical surfaces 3a, 3b,. Is characterized in that it is supported by the diaphragm 3 by point joining at the projections 11 on the recesses 3r at positions adjacent to each other.
[0009]
Piezoelectric speaker of the present invention according to claim 3, the vibration plate 2 attached to the frame 6, the induction coil 7 for electromagnetic coupling which is disposed below the frame 6, is supported by the diaphragm 2 piezoelectric element 5 Toka et The diaphragm 2 is driven by electromagnetic induction, and the diaphragm 2 includes a plurality of semi-cylindrical surfaces 2a, 2b,... Which are adjacent to each other in parallel and have different dimensions, and are square when viewed from the direction of sound waves. The piezoelectric element 5 is adjacent to the plurality of semi-cylindrical surfaces 1a, 1b,... Of the diaphragm 2 in a non-contact state with the frame 6. It is characterized in that it is supported by the diaphragm 1 by line bonding at the recessed portion 2r at the position.
[0010]
The piezoelectric speaker according to a fourth aspect of the present invention is the piezoelectric speaker according to the third aspect, wherein the diaphragm 2 has a dimension in the diameter direction of the semicylindrical surface of the central portion smaller than the dimensions of the semicylindrical surfaces on both sides thereof. It is characterized by being formed.
[0011]
【Example】
First Embodiment Corresponding to Claim 1 An embodiment of the present invention will be described below with reference to the drawings.
FIG. 5 is a perspective view of the diaphragm used in the first embodiment of the present invention. The diaphragm 1 is composed of a plurality of parallel semi-cylindrical surfaces 1a and 1b adjacent to each other, and is attached to a frame (not shown) at outer peripheries 1s and 1s. Reference numeral 1r denotes a recess at a position where the plurality of semi-cylindrical surfaces 1a and 1b of the diaphragm 1 are in contact. The material of the diaphragm 1, polyester, polyimide (PI), in addition sheet of a resin film such as PPTA, silk, etc. are also contemplated.
[0012]
1A is a plan view and FIG. 1B is a front longitudinal sectional view of a first embodiment of the present invention. In the figure, the diaphragm 1 is the same as that described in FIG. The diaphragm 1 is attached to the frame 6 at the outer periphery 1s on both sides. The bimorph-type or unimorph-type piezoelectric element 5 is supported on the back surface of the diaphragm 1 in a non-contact state by the line bonding at the concave portion 1 r of the diaphragm 1. The induced voltage in the induction coil 7 for electromagnetic coupling arranged at the lower part of the frame 6 is applied to the piezoelectric element 5 through the lead wire 9, the relay terminal 10, and the lead wire 8 from the induction coil 7. If the lead wire 9 from the induction coil 7 is directly connected to the electrode of the piezoelectric element 5, the relay terminal 10 and the lead wire 8 become unnecessary.
[0013]
Since this piezoelectric speaker is of an electromagnetic coupling type, it can be used as a tweeter of a coaxial unit because a necessary voltage can be obtained by arranging it on the same axis as the voice coil of a normal dynamic speaker. Further, since the speaker is an electromagnetic coupling type, no electrical wiring is required.
Further, by making the diaphragm shape as shown in FIG. 5, the rigidity in the vibration direction is large and the high-frequency resonance frequency is increased near the junction of the diaphragm 1 and the piezoelectric element 5, thereby widening the reproduction frequency band. it can.
[0014]
FIG. 2 is a frequency characteristic diagram of the output level in the first embodiment of the present invention and the conventional example. In the figure, the vertical axis indicates the output level of the speaker, and the horizontal axis indicates the frequency. The solid line A is the characteristic in the first embodiment of the present invention, and the broken line B is the characteristic in the conventional example. As is apparent from the figure, the solid line A can be reproduced at a higher level than the broken line B, and has a flat characteristic.
[0015]
Example Figure 3 corresponding to claim 3 (a) according to another embodiment of the present invention is a plan view, (b) a front longitudinal sectional view. The diaphragm 2 includes three semi-cylindrical surfaces 2a, 2b, and 2c, and forms two concave portions 2r. The diaphragm 2 is attached to the frame 6 at the outer periphery 2s on both sides. The bimorph-type or unimorph-type piezoelectric element 5 is supported on the diaphragm 2 by line bonding at the two concave portions 2r of the diaphragm 2. In this case, since the semi-cylindrical surface portions having different dimensions are combined, the vibration modes of the respective portions are different and the frequency characteristics thereof are also different. Therefore, the reproduction band is wider and the frequency characteristics are flat. That is, the dimension in the diameter direction of the semicylindrical surface 2b at the center is smaller than the semicylindrical surfaces 2a and 2c on both sides. Further, the piezoelectric element 5 can be easily supported on the diaphragm 2 as compared with the first embodiment, and can be accurately performed.
The others are basically the same as those in the first embodiment, and have the same operations and effects.
[0016]
Another in Example (a) is a plan view of claim 2 Example 4 corresponding to the present invention, (b) is a front longitudinal sectional view. The diaphragm 3 includes two semi-cylindrical surfaces 3a and 3b, and forms a recess 3r. The diaphragm 3 is attached to the frame 6 at the outer periphery 3s on both sides. The center of the bimorph-type or unimorph-type piezoelectric element 5 is supported on the diaphragm 3 by point bonding at a projection 11 on the recess 3r of the diaphragm 3. Therefore, as compared with the first embodiment, by forming the joint portion of the vibration plate 3 with the piezoelectric element 5 in a protruding shape, the movement of the piezoelectric element 5 is transmitted to the vibration plate 3 without waste, and the efficiency is further increased. Is possible.
Although not shown in the figure, if the two protrusions 11 are provided on the recess 3r and the piezoelectric element 5 is supported at two points, the operation is easy and can be performed accurately. The others are basically the same as those in the first embodiment, and have the same operations and effects.
[0017]
【The invention's effect】
According to the first aspect of the present invention, the diaphragm 1 is composed of a plurality of semi-cylindrical surfaces 1a and 1b, the planar shape is a square, and the line-joining portions at the recesses 1r at positions adjacent to each other. Since the piezoelectric element 5 is supported in a non-contact state with the frame 6, a flat frequency characteristic can be obtained, and a piezoelectric speaker that efficiently reproduces a wide band can be obtained.
According to the second aspect of the present invention, the piezoelectric element 5 is not in contact with the frame 6 and the protrusions on the recesses 3r at positions where the plurality of semi-cylindrical surfaces 3a, 3b,. In addition to the above effects, the movement of the piezoelectric element 5 can be transmitted to the diaphragm 3 without waste.
According to the third and fourth aspects of the present invention, since the plurality of semi-cylindrical surfaces 2a, 2b, and 2c are not all the same size and can have different frequency characteristics, the reproduction band can be further widened. Can do.
[Brief description of the drawings]
FIG. 1A is a plan view and FIG. 1B is a front longitudinal sectional view of a first embodiment of the present invention.
FIG. 2 is a frequency characteristic diagram of an output level in the first embodiment of the present invention and a conventional example.
3A is a plan view and FIG. 3B is a front longitudinal sectional view of a second embodiment of the present invention.
4A is a plan view and FIG. 4B is a front longitudinal sectional view of a third embodiment of the present invention.
FIG. 5 is a perspective view of a diaphragm used in the first embodiment of the present invention.
FIG. 6 is a cross-sectional view showing an assembled state of a composite speaker in a conventional example.
[Explanation of symbols]
1, 2, 3 Diaphragm 1a, 1b Semi-cylindrical surface 2a, 2b, 2c Semi-cylindrical surface 3a, 3b Semi-cylindrical surface 1r, 2r, 3r Recess 1s, 2s, 3s Outer periphery 5 Piezoelectric element 6 Frame 7 Inductive coil 8 Lead Wire 9 Lead wire 10 Relay terminal 11 Protrusion 15 Tweeter 19 Diaphragm 20 Woofer 21 Diaphragm 22 Frame 23 Voice coil 24 Damper 25 Magnet 26 Top plate 27 Center pole

Claims (4)

From the diaphragm (1) attached to the frame (6), the induction coil (7) for electromagnetic coupling arranged at the lower part of the frame (6), and the piezoelectric element (5) supported by the diaphragm (1) comprising a piezoelectric speaker is driven by electromagnetic induction,
The diaphragm (1) is in the form a square plurality of semi-cylindrical surface which is parallel and adjacent to each other (1a, 1b · · ·) from viewed from the direction of adult Rutotomoni waves, and the outer peripheral (1s, Attached to the frame (6) in 1s)
The piezoelectric element (5) has a concave portion (a position where the plurality of semi-cylindrical surfaces (1a, 1b...) Of the diaphragm (1) are adjacent to each other in a non-contact state with the frame (6). A piezoelectric speaker, which is supported on the diaphragm (1) by wire bonding in 1r). From the diaphragm (3) attached to the frame (6), the induction coil (7) for electromagnetic coupling arranged at the lower part of the frame (6), and the piezoelectric element (5) supported by the diaphragm (3) comprising a piezoelectric speaker is driven by electromagnetic induction,
The diaphragm (3) is in the form a square from each plurality of semi-cylindrical surface which is parallel and adjacent to (3a, 3b · · ·) as viewed from the direction of adult Rutotomoni waves, and the outer peripheral (3s, Attached to the frame (6) in 3s)
The piezoelectric element (5) has a concave portion (a position where the plurality of semi-cylindrical surfaces (3a, 3b...) Of the diaphragm (3) are adjacent to each other in a non-contact state with the frame (6). 3r) A piezoelectric speaker characterized in that it is supported on the diaphragm (3) by point joining at the projection (11) on the top. From the diaphragm (2) attached to the frame (6), the induction coil (7) for electromagnetic coupling arranged at the lower part of the frame (6), and the piezoelectric element (5) supported by the diaphragm (2) A piezoelectric speaker driven by electromagnetic induction,
The diaphragm (2) is formed of a plurality of semi-cylindrical surfaces (2a, 2b,...) That are adjacent to each other in parallel and have different dimensions, have a square shape when viewed from the direction of sound waves, and have a frame around the periphery thereof. Attached to (6),
The piezoelectric element (5) has a recess (a position where the plurality of semi-cylindrical surfaces (1a, 1b...) Of the diaphragm (2) are adjacent to each other in a non-contact state with the frame (6). A piezoelectric speaker, which is supported on the diaphragm (1) by line bonding in 2r). 4. The piezoelectric speaker according to claim 3, wherein the diaphragm 2 is formed such that the diameter of the semicylindrical surface of the central portion is smaller than the dimensions of the semicylindrical surfaces on both sides thereof.

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