JP2012019317A - Actuator and speaker having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an actuator which efficiently outputs a comparatively large and high vibration and has excellent productivity, and also to provide a speaker having the same.SOLUTION: An actuator 1 includes: a plate-like piezoelectric substance 2; a plurality of thin film shape and rectangular diaphragms 3 which are oppositely arranged on the front surface of the piezoelectric substance so as to allow the both side edges to be substantially vertical to a telescopic direction of the piezoelectric substance; and a plurality of frames 4 for fixedly positioning the both side edges of the plurality of diaphragms and transmitting the telescopic motion of the piezoelectric substance to the plurality of diaphragms.

Description

  The present invention relates to an actuator using a piezoelectric body and a speaker including the actuator.

  An actuator using a piezoelectric material has an advantage that the structure can be simplified as compared with an electrodynamic converter including a magnet and a coil and a capacitor converter. For this reason, actuators using piezoelectric materials have been developed having various structures as acoustic parts such as microphones and speakers.

  Specifically, an actuator using such a piezoelectric material includes (1) a multi-resonance ultrasonic actuator having a unimorph structure (see JP 2008-20429 A), and (2) a planar piezoelectric vibrator. Actuator having a structure in which a diaphragm is disposed so as to cover at least one side (see JP 2001-15823 A, JP 2008-526416 A, JP 2000-502210 A, etc.), (3) Two piezoelectric elements There has been proposed an actuator (see JP-A-2003-258330, etc.) having a structure in which a flexible member bridged between them vibrates.

  However, in the actuator having the unimorph structure of (1), it is necessary to make the piezoelectric body thin in order to increase the amplitude of the piezoelectric body. In this case, the force generated by the vibration of the piezoelectric body is not strong. It is difficult to output a vibration having a large amplitude. In addition, the actuator having a structure in which the diaphragm is disposed so as to cover at least one surface of the planar piezoelectric vibrator of (2) is difficult to increase the resonance frequency of the diaphragm with respect to the piezoelectric vibrator. Is difficult to output. In this actuator, if the rigidity of the diaphragm is increased in order to increase the resonance frequency of the diaphragm, the diaphragm obstructs the vibration motion of the piezoelectric vibrator. Furthermore, the actuator having a structure in which the flexible member bridged between the two piezoelectric elements in (3) vibrates needs to be assembled by accurately positioning the two piezoelectric elements and the flexible member, and it is difficult to improve accuracy. It has the disadvantage of being.

JP 2008-20429 A JP 2001-15823 A Special table 2008-526416 JP 2000-502210 JP JP 2003-258330 A

  The present invention has been made on the basis of such inconveniences, and is capable of efficiently outputting vibration having a relatively large amplitude and a high frequency. In addition, an actuator excellent in productivity and a speaker including the actuator are provided. The purpose is to provide.

The invention made to solve the above problems is
A plate-like piezoelectric body;
A plurality of thin-film and rectangular diaphragms disposed opposite to the surface of the piezoelectric body so that both side edges are substantially perpendicular to the expansion and contraction direction of the piezoelectric body;
The actuator includes: a plurality of frames that fix both side edges of the plurality of diaphragms and transmit the expansion and contraction movement of the piezoelectric body to the plurality of diaphragms.

  The actuator has a plurality of thin film diaphragms disposed at positions facing the piezoelectric body, and the expansion and contraction motion of the piezoelectric body is transmitted to each diaphragm via the frame. Can be vibrated efficiently with the side edges as nodes. Further, according to the actuator, it is possible to output vibration having a large amplitude by adjusting the thickness, shape, size, etc. of the diaphragm and the piezoelectric body. In addition, according to the said actuator, since a diaphragm is a thin film form, it is hard to prevent the expansion-contraction movement of a piezoelectric material, Therefore A diaphragm can be vibrated efficiently. Further, according to the actuator, since each diaphragm has a square shape, the resonance frequency can be set high by narrowing the width, and further, by matching with the resonance frequency of the piezoelectric body, More efficient vibration output is possible. Further, the actuator is easy to process because it is not necessary to make the piezoelectric body into a thin film, and is excellent in productivity.

  The plurality of diaphragms may be formed from a single thin film. According to the actuator, by forming the plurality of diaphragms from a single thin film, the manufacturing can be made efficient and the resonance frequency of each diaphragm can be easily set.

  The plurality of diaphragms may have the same width. According to the actuator, by making the widths of the plurality of diaphragms equal, the frequencies of the diaphragms can be equalized, and uniform vibration with less noise can be output.

  The diaphragm is preferably curved in the width direction. According to the actuator, since the diaphragm is curved in this way, the displacement of the diaphragm due to the vibration of the piezoelectric body can be increased. Therefore, according to the actuator, vibration having a large amplitude can be output more efficiently. In addition, according to the actuator, since the diaphragm is curved in this way, vibration with the width of each diaphragm as a basic vibration is likely to occur, and on the other hand, generation of a secondary or higher vibration mode can be suppressed. Therefore, the frequency controllability of the output vibration is improved.

  In the actuator, it is preferable that the diaphragm vibrates at a frequency that is half the vibration frequency of the piezoelectric body. According to the actuator, by adjusting the width of the piezoelectric body and each diaphragm, the diaphragm is vibrated at a frequency half that of the piezoelectric body, that is, the diaphragm is excited parametrically. Miniaturization is possible, and more efficient vibration output is possible.

  The speaker of the present invention includes the actuator. Since the speaker includes the above-described actuator, the speaker can efficiently transmit a sound wave having a relatively large amplitude and a high frequency, and has excellent productivity.

  As described above, the actuator of the present invention is excellent in productivity because it can efficiently output vibration having a relatively large amplitude and a high frequency and does not require complicated machining. Therefore, the speaker of the present invention can efficiently transmit a sound wave having a relatively large amplitude and a high frequency, so that the output of the speaker can be increased, and in addition, it has excellent productivity. ing.

(A) is a typical perspective view which shows the actuator which concerns on 1st Embodiment of this invention, (b) is the fragmentary sectional view. (A)-(d) is typical fragmentary sectional drawing which shows the vibration state of the actuator of FIG. (A)-(e) is typical sectional drawing which shows the manufacturing process of the actuator of FIG. It is a typical fragmentary sectional view showing the actuator concerning a 2nd embodiment of the present invention. (A)-(e) is a typical fragmentary sectional view which shows the actuator which concerns on other embodiment, respectively.

  Hereinafter, embodiments of an actuator of the present invention and a speaker including the actuator will be described in detail with reference to the drawings as appropriate.

<First Embodiment>
The actuator 1 in FIG. 1 includes a plate-like piezoelectric body 2, a plurality of thin-film and rectangular diaphragms 3 disposed to face the surface of the piezoelectric body 2, and the plurality of diaphragms 3. It mainly includes a plurality of frames 4 that place both side edges.

  The actuator 1 has a plurality of thin-film diaphragms 3 arranged at positions facing the surface of the piezoelectric body 2 in this way. Further, as described above, each diaphragm 3 is fixed at both side edges by the frame 4, that is, each diaphragm 3 is disposed so as not to move to a position determined with respect to the piezoelectric body 2. . Therefore, in the actuator 1, the expansion / contraction motion of the piezoelectric body 2 is transmitted to each diaphragm 3 through the plurality of frames 4, and each diaphragm 3 can be vibrated efficiently with the both side edges as nodes. Further, according to the actuator 1, vibration having a large amplitude can be output by adjusting the thickness, shape, size, and the like of the diaphragm 3 and the piezoelectric body 2.

  Further, according to the actuator 1, since the diaphragm 3 is in a thin film shape, the diaphragm 3 can hardly vibrate the expansion and contraction motion of the piezoelectric body 2, so that the diaphragm 3 can be vibrated efficiently. Further, according to the actuator 1, since each diaphragm 3 has a square shape, the resonance frequency can be set high by narrowing this width (length in the direction perpendicular to both side edges), etc. Furthermore, by combining with the resonance frequency of the piezoelectric body 2, it is possible to output vibration with higher efficiency. Furthermore, the actuator 1 is easy to process because the piezoelectric body 2 does not need to be formed into a thin film, and is excellent in productivity.

  The piezoelectric body 2 has a plate-like piezoelectric material 5 and a pair of electrode films 6 laminated on both surfaces of the piezoelectric material 5. The piezoelectric body 2 expands and contracts (vibrates) in one direction (X direction in FIG. 1A) by applying an alternating voltage to the pair of electrode films 6 or the like. In order to improve the stretchability in the X direction, the piezoelectric body 2 preferably has a rectangular shape in plan view with the X direction as the long side and the Y direction as the short side.

  The size of the piezoelectric body 2 is not particularly limited, and can be appropriately set according to the frequency of vibration to be output and the size of a speaker to be used. For example, when this actuator 1 is used as an ultrasonic speaker, the piezoelectric body 2 can be formed into a plate shape having a length of 1 to 4 cm and a thickness of 0.1 to 1 cm.

  The piezoelectric material 5 is not particularly limited as long as it is a material that causes an electric field induced strain such as a piezoelectric effect. For example, a ceramic, a polymer such as PVDF (polyvinylidene fluoride), or a ceramic can be used. And a complex of polymer and polymer. The piezoelectric material 5 may be crystalline or amorphous. Among these piezoelectric materials 5, ceramics are preferable in terms of strength, moldability, piezoelectric characteristics, and the like. As these ceramics, semiconductor ceramics, ferroelectric ceramics, antiferroelectric ceramics, and the like can also be used.

  Specific materials constituting the ceramic include, for example, lead zirconate, lead titanate, lead magnesium niobate, lead nickel niobate, lead zinc niobate, lead manganese niobate, lead antimony stannate, lead manganese tungstate, cobalt Examples thereof include lead niobate, barium titanate, sodium bismuth titanate, bismuth neodymium titanate, lead zirconate titanate (PTZ), potassium sodium niobate, strontium bismuth tantalate, and the like alone or as a mixture or Ceramics contained as a solid solution can be used.

  The material of the electrode film 6 is not particularly limited as long as it has conductivity and is solid at room temperature, and examples thereof include simple metals, alloys and the like, and also include zirconium oxide, hafnium oxide, titanium oxide, cerium oxide. It may be a mixture of an insulating ceramic such as a single metal or an alloy thereof.

  The plurality of diaphragms 3 have their both side edges substantially perpendicular to the expansion / contraction direction (X direction) of the piezoelectric body 2, that is, both side edges extend in the Y direction, and are spaced from the surface of the piezoelectric body 2 by a predetermined distance. The piezoelectric body 2 is arranged in parallel with the surface. Moreover, each diaphragm 3 is arrange | positioned at equal intervals and in parallel.

  Here, the both side edges of the diaphragm 3 are “substantially perpendicular” to the expansion / contraction direction of the piezoelectric body 2. It does not have to be vertical. The angle formed between the expansion / contraction direction of the piezoelectric body 2 and both side edges of the diaphragm 3 is preferably 80 ° to 100 °, more preferably 85 ° to 95 °, and particularly preferably 88 ° to 92 °. .

  Each diaphragm 3 is curved in a concave shape in its width direction (X direction in FIG. 1). According to the actuator 1, it is possible to increase the displacement of the diaphragm 3 due to the vibration of the piezoelectric body 2 by bending the diaphragm 3 in this way. Therefore, according to the actuator 1, vibration having a large amplitude can be output more efficiently. In addition, according to the actuator 1, by bending the diaphragm 3 in this way, vibration with the width of each diaphragm 3 as a basic vibration is likely to occur, and on the other hand, the generation of a secondary or higher vibration mode is suppressed. Therefore, the frequency controllability of the output vibration is improved.

  Between each diaphragm 3, a strip-like and thin-film connecting plate 7 is disposed, and the plurality of diaphragms 3 and the plurality of connecting plates 7 are formed of a single, that is, one thin film. According to the actuator 1, by forming the plurality of diaphragms 3 together with the plurality of connecting plates 7 from a single thin film, the manufacturing can be made efficient, and the resonance frequency of each diaphragm 3 can be set. Can be easily.

  The size of the diaphragm 3 is not particularly limited, but the length of the side edge (length direction: Y direction) is approximately the same as the length of the piezoelectric body 2 in the lateral direction (Y direction) (for example, 1 to 4 cm). It is preferable that

The width (W ₁ : length in the X direction) of the diaphragm 3 can be appropriately adjusted depending on the frequency of vibration to be output. For example, when used as an ultrasonic speaker, the width (W ₁ ) is preferably from 0.1 mm to 10 mm, and more preferably from 0.5 mm to 5 mm. Each diaphragm 3 has a belt-like shape in which the length of the side edge (length in the Y direction) is larger than the width (length in the X direction) in this way. Since each diaphragm 3 has a strip shape, efficient vibration output can be performed. The shape of the diaphragm 3 is not limited to a belt-like shape as long as it is a square shape, and may be a square shape or a rectangular shape in which the length of both side edges is smaller than the width.

In addition, the width (W ₁ ) of each of the plurality of diaphragms 3 is substantially the same. According to the actuator 1, by making the widths of the plurality of diaphragms 3 the same in this way, the vibration frequencies of the diaphragms 3 can be made equal and uniform vibrations with less noise can be output. The widths of the plurality of diaphragms 3 are substantially the same. The thin films forming the diaphragms 3 can vibrate at the same frequency with the connecting plate 7 between the diaphragms 3 as a node. If there is, it means that there may be a slight shift in each width.

  The average thickness (T) of the diaphragm 3, that is, the thin film forming the plurality of diaphragms 3 is not particularly limited as long as each diaphragm 3 can be vibrated by the vibration of the piezoelectric body 2, but is preferably 10 μm or more and 100 μm or less. 20 μm or more and 80 μm or less is more preferable. By providing the diaphragm 3 with a thin film having an average thickness (T) in the above range, the diaphragm 3 can be efficiently vibrated by the vibration of the piezoelectric body 2.

  The depth (D) of the curved portion of the diaphragm 3 is preferably, for example, 10 μm or more and 500 μm or less, and more preferably 20 μm or more and 300 μm or less. By setting the depth of the curved portion of the diaphragm 3 within this range, each diaphragm 3 can be easily vibrated largely symmetrically with respect to the plane including each connecting plate 7. If the depth (D) is smaller than the lower limit, the amplitude of the output vibration may be reduced. Conversely, if the depth (D) exceeds the upper limit, the vibration plate 3 may not vibrate greatly due to the vibration of the piezoelectric body 2. There is.

  The shape of the curved portion of the diaphragm 3 is not particularly limited as long as it is curved in the width direction (X direction). For example, as a cross section in the XZ plane, isosceles trapezoidal shape, isosceles triangular shape Other polygonal shapes, shapes obtained by rounding these vertices, semicircular shapes, sinusoidal shapes, and the like may be used.

  The material of the thin film forming the diaphragm 3 and the connecting plate 7 is not particularly limited as long as the diaphragm 3 can vibrate by the vibration of the piezoelectric body 2, and may be an organic material such as polyimide resin or polyester resin, It may be a metal such as aluminum, copper, titanium or an alloy, or an inorganic material such as a metal oxide. In view of strength and formability in sputtering described later, metals such as aluminum and titanium are preferable.

  Each of the plurality of frames 4 has a quadrangular prism shape. Each frame 4 connects the back surface of each connecting plate 7 and the surface side of the piezoelectric body 2, and both side edges of the plurality of diaphragms 3 are fixed, that is, the positions of both side edges of each diaphragm 3 are in the piezoelectric body 2. They are arranged so that they do not move. In other words, the arrangement direction of the frames 4 is laid such that the plurality of frames 4 are perpendicular to the expansion / contraction direction (X direction) of the piezoelectric body 2 and the length direction is the Y direction. In addition, among the plurality of frames 4, a pair of frames disposed at both ends are wider than the other frames, and transmission of expansion / contraction vibration of the piezoelectric body 2 to the diaphragms 3 at both ends is ensured. Yes.

  The height of each frame 4 (H: length in the Z direction) is the distance between the piezoelectric body 2 and the diaphragm 3. Although it does not specifically limit as height (H: the length of a Z direction) of the flame | frame 4, For example, 0.5 mm or more and 10 mm or less are preferable, and 1 mm or more and 5 mm or less are more preferable. The length of the frame 4 (the length in the Y direction) may be about the same as the length of the piezoelectric body 2 in the Y direction, and is about 1 to 4 cm, for example.

The width (length in the X direction) of the frame 4 is not particularly limited, but among the plurality of frames 4 arranged in parallel, the width of the frames 4b at both ends is about 0.5 mm to 5 mm. In addition, the width (W ₂ ) of the frame 4 a other than both ends connecting the two diaphragms 3 is preferably 100 μm or more and 500 μm or less. Thus, by making the width of the frame 4b at both ends wider than the width of the frame 4a other than the other ends, an appropriate strength can be given to the actuator 1, and the vibration to the diaphragm 3 can be reduced as described above. Transmission can be ensured.

  The material of the frame 4 is not particularly limited as long as it can transmit the expansion and contraction motion of the piezoelectric body 2 to the diaphragm 3, and may be an inorganic material such as a metal or non-metal, or an organic material. From the viewpoint of properties, inorganic substances are preferred. Moreover, as will be described in detail later, inorganic materials such as silicon that can be formed by etching are more preferable.

  The adhesive layer 8 is laminated on the surface of the piezoelectric body 2 on the vibration plate 3 side. The adhesive layer 8 connects and fixes the piezoelectric body 2 and each frame 4. A material for forming the adhesive layer 8 is not particularly limited, and a known adhesive or pressure-sensitive adhesive can be used. The adhesive layer does not have to be laminated on the entire surface of the piezoelectric body 2 on the vibration plate 3 side, and may be laminated between the piezoelectric body 2 and each frame 4.

  The piezoelectric body 2 is held in the housing 10 by the support portion 9. The support portion 9 has a quadrangular prism shape, and is disposed in parallel with each frame 4 in the center of the surface of the piezoelectric body 2 on the side opposite to the diaphragm 3. Since the support portion 9 is thus provided perpendicular to the vibration direction of the piezoelectric body 2, the piezoelectric body 2 can vibrate without being blocked by the support portion 9.

  The actuator 1 vibrates when the drive signal is applied from a signal source (not shown) connected to the pair of electrode films 6. The vibration of the piezoelectric body 2 is transmitted to the diaphragm 3 through each frame 4, and each diaphragm 3 vibrates. In other words, according to the actuator 1, since the plurality of diaphragms 3 are formed from a single thin film, the single thin film vibrates with the connecting plate 7 connected to the plurality of frames 4 as a node. It will be.

  Since the actuator 1 has the above-described structure, the amplitude of each diaphragm 3 is large, and the generation of secondary or higher vibration modes of the diaphragm 3 is suppressed. Therefore, the actuator 1 can be suitably used as an ultrasonic transmitter such as an ultrasonic speaker.

  Here, in the actuator 1, it is preferable that each diaphragm 3 is designed to vibrate at a frequency that is ½ of the vibration frequency of the piezoelectric body 2. Since the actuator 1 has the expansion / contraction (vibration) direction of the piezoelectric body 2 and both side edges of each diaphragm 3 arranged substantially perpendicularly, the piezoelectric body 2 is designed by the design as shown in FIG. While (a) to (b) to (c) to (d) to (a), each diaphragm 3 vibrates for one period, that is, the diaphragm 3 can be parametrically excited. In FIG. 2, the degree of expansion / contraction is exaggerated in order to schematically represent the relationship between expansion / contraction of the piezoelectric body 2 and vibration of the diaphragm 3. Thus, in order to make each diaphragm 3 in a state in which parametric excitation is possible, the size and material of the piezoelectric body 2 and the material and width of the diaphragm 3 may be adjusted.

  Thus, by vibrating each diaphragm 3 parametrically (vibrating at a frequency that is half the vibration frequency of the piezoelectric body 2), the length of the piezoelectric body 2 is half that of the case of using normal resonance vibration. Therefore, the actuator 1 can be downsized. In addition, when the diaphragm 3 is parametrically excited, a vibration having a half frequency is output from the diaphragm as compared with an actuator (piezoelectric body) of the same size. Can be done automatically. Furthermore, since the displacement can be increased by parametric excitation, the output efficiency can be improved.

<Speaker>
The speaker including the actuator 1 can efficiently transmit a sound wave having a relatively large amplitude and a high frequency, and has excellent productivity. In addition, the frequency of the ultrasonic wave transmitted from the ultrasonic speaker including the actuator 1 can be appropriately set by adjusting the size and material of the piezoelectric body 2 and the diaphragm 3, the material, the interval between the frames 4, and the like. However, for example, a frequency of 20 kHz to 100 kHz can be transmitted.

<Manufacturing method>
The manufacturing method of the actuator 1 is not particularly limited, and a known method can be used. An example of the manufacturing method will be described below with reference to FIG.

  The surface of the silicon substrate 11 serving as each frame is subjected to anisotropic wet etching by a known method so as to form a curved shape of the diaphragm (see FIG. 3A). A thin film 12 made of, for example, aluminum is formed on the etched surface of the silicon substrate 11 by sputtering, vacuum deposition, or the like (see FIG. 3B). The aluminum thin film 12 becomes the diaphragm 3 and the connecting plate 7. At a position corresponding to the curved shape of the back surface of the silicon substrate 11 on which the thin film 12 is formed, a plurality of rod-shaped grooves 13 having a high aspect ratio are formed so as to leave the aluminum thin film 12 by, for example, deep digging RIE. (Refer FIG.3 (c)). The grooves 13 form the outer shape of the plurality of frames 4.

  On the other hand, an adhesive layer 8 is provided by applying a general adhesive on the surface of the piezoelectric body 2 in which the electrode film 6 is laminated by a known method on both surfaces of the plate-like piezoelectric material 5 (FIG. 3D). reference). Subsequently, the piezoelectric body 2 is bonded to the back surface (the bottom surface of each frame) of the silicon substrate 11 obtained through the above-described process (see FIG. 3E), and the back surface of the piezoelectric body 2 is further supported by the support portion 9. The actuator shown in FIG. 1 can be obtained by being fixed to the housing 10 via. The actuator (structure) in the state of FIG. 3 (e) is provided with an electric circuit that connects the pair of electrode films 6 and the signal source by a known method as described above.

  In the etching of the front and back surfaces of the silicon substrate 11, it is not easy to form the groove 13 having the same shape up to both ends (Y direction both ends in FIG. 1A). After bonding, the both end portions where the groove 13 (frame 4) is not formed are cut to obtain an actuator in which the frame 4 is formed up to both ends (Y direction both ends in FIG. 1A). it can.

<Second Embodiment>
The actuator 21 according to the second embodiment of FIG. 4 includes a plate-like piezoelectric body 2 and a plurality of thin-film and rectangular (band-like) diaphragms 23 disposed to face the surface of the piezoelectric body 2. The plurality of frames 4 for fixing both side edges of the plurality of diaphragms 23 are mainly provided.

  Since the piezoelectric body 2 and the plurality of frames 4 of the actuator 21 are the same as those of the actuator 1 according to the first embodiment, the same reference numerals are given and description thereof is omitted. In addition, the actuator 21 has a support portion, a housing, and the like (not shown) as in the actuator 1.

  Like the actuator 1, the connecting plate 7 is disposed between the plurality of diaphragms 23, and the plurality of diaphragms 23 and the plurality of connecting plates 7 are formed from a single thin film. However, unlike the diaphragm 3 of the actuator 1, the diaphragm 23 is not curved and has a planar shape.

  Also in the actuator 21, the vibration of the piezoelectric body 2 can be transmitted to the diaphragm 23 via the frame 4, and the piezoelectric body 2 and the diaphragm 23 do not directly overlap with each other. It can easily vibrate in both directions. Also, in the actuator 21, by adjusting the size and material of the piezoelectric body 2 and the diaphragm 23, for example, by combining the resonance frequencies of the piezoelectric body 2 and the diaphragm 23, vibration having a large amplitude is generated. Can be output. Also in the actuator 21, each diaphragm 23 vibrates, that is, one thin film vibrates with the connecting plate 7, which is a contact portion with the frame 4, as a node, so that high-frequency vibration is efficiently output. be able to.

  Also, the actuator 21 can be set so that each diaphragm 23 vibrates at a frequency half that of the vibration frequency of the piezoelectric body 2. According to the actuator 21 set in this way, each diaphragm 23 is parametrically excited, so that the actuator 21 can be miniaturized and more efficient vibration can be output.

  This actuator 21 can also be manufactured by etching a silicon substrate, like the actuator 1 described above. When a silicon substrate having a silicon oxide layer on the surface is used, the silicon oxide layer on the surface can be used as a diaphragm. Further, if an SOI substrate is used, a thin film silicon film can be used as a vibration plate.

<Other embodiments>
In the actuator 31 shown in FIG. 5A, a plurality of groove-like fitting portions 14 are formed on the surface of the piezoelectric body 32, and a plurality of the fitting portions 14 are interposed via adhesive layers 38. It has a shape in which the frame 34 is fitted.

  Since the actuator 31 has a structure in which each frame 34 is embedded in the fitting portion 14 of the piezoelectric body 32 as described above, the position of the frame 34 does not shift due to vibration or the like. Therefore, according to the actuator 31, the vibration of the piezoelectric body 32 can be transmitted to the diaphragm 33 more efficiently, and the vibration having a large amplitude and suppressing the occurrence of secondary or higher resonance can be output. it can.

  In the actuator 41 shown in FIG. 5B, the adhesive layer 48 is not laminated between the frame 4a other than both ends and the piezoelectric body 2, that is, the bottom surface of the frame 4a other than both ends and the surface of the piezoelectric body 2. And are not bonded.

  Also in such an actuator 41, the vibration of the piezoelectric body 2 is conducted to each diaphragm 3 through the frames 4b at both ends, and each diaphragm 3 can vibrate. At this time, even in the frames 4a other than both ends where the bottom surfaces are not bonded, the both side edges of each diaphragm 3 are not moved relative to the piezoelectric body 2 by the mass of the frames themselves, that is, they are stationary. Each diaphragm 3 can vibrate with both side edges as nodes.

  Unlike the actuator 41 shown in FIG. 5B, the actuator 51 shown in FIG. 5C has a structure in which the frames 54b at both ends of the plurality of frames are not provided on one surface side of the piezoelectric body 2. ing. That is, the frames 54 b at both ends are disposed on the side surfaces of both ends of the piezoelectric body 2 so that the piezoelectric body 2 and the diaphragm 3 are in parallel via the adhesive layer 58. Further, in the actuator 61 shown in FIG. 5D, a support portion 69 is provided on the side surface of the piezoelectric body 2 and connects the piezoelectric body 2 and the housing 60. The actuator 71 shown in FIG. 5E has a fixed structure in which the lower surface of one end edge of the piezoelectric body 2 in the expansion / contraction direction is in contact with the housing 70 without using a support portion. Further, as a different actuator, there may be mentioned an actuator in which a diaphragm that is curved in the width direction is curved with respect to the outer side (the side opposite to the piezoelectric body). In any of these actuators, the vibration of the piezoelectric body can be transmitted to each diaphragm via a plurality of frames, so that a vibration having a large amplitude can be output, and each diaphragm has nodes on both side edges as nodes. Since it vibrates, high frequency vibration can be output efficiently.

  Further, the plurality of diaphragms in the actuator of the present invention may not be provided in parallel to the surface of the piezoelectric body. Even in such an actuator, for example, provided with a diaphragm obliquely to the surface of the piezoelectric body, if both side edges of the diaphragm are disposed substantially perpendicular to the expansion and contraction direction of the piezoelectric body, It is possible and the effect of this invention can be exhibited.

  Further, a piezoelectric body having a bimorph or monomorph structure formed by laminating one or two piezoelectric materials may be used. If the piezoelectric body has such a structure, the piezoelectric body can bend and vibrate, and the diaphragm can be greatly deformed. Therefore, the amplitude of each diaphragm can be increased.

  As described above, the actuator of the present invention can output relatively large and high vibrations efficiently and does not require complicated processing, so it is excellent in productivity. It can be suitably used for a transmitter or the like.

1, 2, 31, 41, 51, 61, 71 Actuator 2, 32 Piezoelectric body 3, 23, 33 Diaphragm 4, 34 Frame 4a Frame 4b other than both ends 4b, 54b Frame at both ends 5 Piezoelectric material 6 Electrode film 7 Connecting plate 8, 38, 48, 58 Adhesive material layer 9, 69 Support part 10, 60, 70 Housing 11 Silicon substrate 12 Thin film 13 Groove 14 Insertion part

Claims (6)

A plate-like piezoelectric body;
A plurality of thin-film and rectangular diaphragms disposed opposite to the surface of the piezoelectric body so that both side edges are substantially perpendicular to the expansion and contraction direction of the piezoelectric body;
An actuator comprising: a plurality of frames that place both side edges of the plurality of diaphragms and transmit the expansion and contraction motion of the piezoelectric body to the plurality of diaphragms.   The actuator according to claim 1, wherein the plurality of diaphragms are formed from a single thin film.   The actuator according to claim 1, wherein the plurality of diaphragms have the same width.   The actuator according to claim 1, wherein the diaphragm is curved in the width direction.   The actuator according to any one of claims 1 to 4, wherein the diaphragm vibrates at a frequency half that of a piezoelectric body. A speaker provided with the actuator of any one of Claims 1-5.

Images