JP2012217013A - Oscillation device and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a larger output in an oscillation device that has a piezoelectric element as an oscillation source.SOLUTION: A piezoelectric element 20 is arranged above a bottom portion of a support member 40. The piezoelectric element 20 has a first surface attached to a bottom surface of the support member 40, and a second surface, which is opposite to the first surface, attached to a vibrating member 10. Electrodes 22 and 24 apply voltage between the first surface and the second surface of the piezoelectric element 20. When a driving signal is input between the electrodes 22 and 24, thus, the piezoelectric element 20 expands and contracts vertically in the figure, and, as a result, the whole vibrating member 10 vibrates vertically. Accordingly, the oscillation device produces a large output.

Description

  The present invention relates to an oscillation device and an electronic apparatus.

  One type of speaker is used as an oscillation source in which a piezoelectric element is fixed on a vibrating member. This type of speaker is characterized in that it is easy to miniaturize compared to an electrodynamic speaker using a voice coil and a magnet. A speaker using a piezoelectric element flexures and vibrates the diaphragm by mounting the piezoelectric element on the diaphragm (see, for example, Patent Document 1).

JP 2007-251271 A

  An oscillation device using a piezoelectric element is difficult to increase the output.

  An object of the present invention is to provide an oscillation device and an electronic device that use a piezoelectric element as an oscillation source and can increase the output.

According to the present invention, a support member;
A vibration member disposed above the support member;
A piezoelectric element, wherein one surface is attached to the support member, and an opposite surface that is a surface opposite to the one surface is attached to the vibration member;
An electrode for applying a voltage between the one surface and the opposite surface of the piezoelectric element;
An oscillation device is provided.

According to the present invention, a support member having a bottom and a side,
A first vibration member disposed above the bottom of the support member and having an edge facing the side of the support member;
A piezoelectric element attached to the vibrating member;
A second vibrating member that connects the edge of the first vibrating member and the side of the support member, and is formed of a material that is more flexible than the first vibrating member;
A first fixing member having one end attached to the second vibrating member and the other end fixed to the bottom of the support member;
An oscillation device is provided.

  According to this embodiment, an electronic apparatus having the above-described oscillation device is provided.

  According to the present invention, an output can be increased in an oscillation device using a piezoelectric element as an oscillation source.

It is a figure which shows the structure of the oscillation apparatus which concerns on 1st Embodiment. It is the figure which expanded the principal part of FIG. It is a figure which shows the structure of the electronic device which concerns on 2nd Embodiment. It is a figure which shows the structure of the oscillation apparatus which concerns on 3rd Embodiment. It is a figure which shows the structure of the oscillation apparatus which concerns on 4th Embodiment. It is a figure which shows the structure of the oscillation apparatus which concerns on 5th Embodiment. It is sectional drawing which shows the structure of the oscillation apparatus which concerns on 6th Embodiment. It is sectional drawing which shows the modification of FIG. FIG. 8 is a plan view of the oscillation device illustrated in FIG. 7. It is a top view which shows the modification of FIG. FIG. 10 is a diagram illustrating an example in which the oscillation device illustrated in FIGS. 7 to 9 is arranged in a housing of an electronic device. It is a top view which shows the structure of the oscillation apparatus which concerns on 7th Embodiment. It is a figure which shows the structure of the oscillation apparatus which concerns on 8th Embodiment. It is a figure which shows the structure of the oscillation apparatus which concerns on 9th Embodiment. It is a figure which shows the structure of the oscillation apparatus which concerns on 10th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

(First embodiment)
FIG. 1 is a diagram illustrating the configuration of the oscillation device according to the first embodiment. FIG. 2 is an enlarged view of a main part of FIG. This oscillation device includes a support member 40, a vibration member 10, a piezoelectric element 20, and electrodes 22 and 24. In the example shown in the figure, the support member 40 has a box shape and includes a bottom portion, a side portion, and an upper portion. The piezoelectric element 20 is disposed above the bottom of the support member 40. One surface of the piezoelectric element 20 is attached to the bottom surface of the support member 40, and the opposite surface, which is the surface opposite to the one surface, is attached to the vibration member 10. The electrodes 22 and 24 apply a voltage between one surface and the opposite surface of the piezoelectric element 20. Therefore, when a drive signal for the piezoelectric element 20 is input between the electrodes 22 and 24, the piezoelectric element 20 expands and contracts in the vertical direction in the figure, and as a result, the entire vibration member 10 vibrates up and down. Therefore, the output of the oscillation device can be increased. Details will be described below.

  The vibration member 10 has a sheet shape, and the end portion is not constrained. The vibrating member 10 adjusts the basic resonance frequency of the piezoelectric element 20. The fundamental resonance frequency of the mechanical vibrator depends on the load weight and compliance. Since the compliance is the mechanical rigidity of the vibrator, the basic resonance frequency of the piezoelectric element 20 can be controlled by controlling the rigidity of the vibration member 10. The thickness of the vibration member 10 is preferably 5 μm or more and 500 μm or less. Further, the vibration member 10 preferably has a longitudinal elastic modulus, which is an index indicating rigidity, of 1 GPa or more and 500 GPa or less. When the rigidity of the vibration member 10 is too low or too high, there is a possibility that characteristics and reliability as a mechanical vibrator are impaired. The material constituting the vibration member 10 is not particularly limited as long as it is a material having a high elastic modulus with respect to the piezoelectric element 20 that is a brittle material, such as metal or resin, but phosphor bronze or the like in terms of workability and cost. Stainless steel or the like is preferable.

  The piezoelectric element 20 is formed of piezoelectric ceramics such as PZT. However, the piezoelectric element 20 may be formed of a polymer material exhibiting piezoelectric characteristics, such as polyvinylidene fluoride.

Although the material which comprises the electrodes 22 and 24 is not specifically limited, For example, silver and silver / palladium can be used. Since silver is used as a general-purpose electrode material with low resistance, it has advantages in manufacturing process and cost. Since silver / palladium is a low-resistance material excellent in oxidation resistance, there is an advantage from the viewpoint of reliability. The thickness h ₂ of the electrodes 22 and 24 is not particularly limited, but the thickness h ₂ is preferably 1 μm or more and 50 μm or less. The thickness h ₂ is less than 1 [mu] m, it becomes difficult to mold the electrodes 22 and 24 uniformly, as a result, the electromechanical conversion efficiency may be lowered. Moreover, when the film thickness of the electrodes 22 and 24 exceeds 100 micrometers, the electrodes 22 and 24 become a restraint surface with respect to the piezoelectric body of the piezoelectric element 20, and there exists a possibility that energy conversion efficiency may fall.

  In the present embodiment, the piezoelectric element 20 is smaller than the vibration member 10 in plan view. The piezoelectric elements 20 are columnar, and a plurality of the piezoelectric elements 20 are provided apart from each other. For example, the piezoelectric elements 20 are provided at equal intervals on a circumference concentric with the center of the vibration member 10 in plan view.

  As described above, the support member 40 has a box shape, and the vibration member 10 and the piezoelectric element 20 are disposed inside the support member 40. Specifically, the piezoelectric element 20 is disposed on the bottom surface of the support member 40, and the vibration member 10 is disposed on the piezoelectric element 20. A sound hole 46 is formed on the upper surface of the support member 40. The sound hole 46 faces the vibration member 10. Sound waves generated by the vibration of the vibration member 10 are radiated to the outside through the sound holes 46.

  Further, the oscillation device has a control unit 50. The control unit 50 generates a drive signal based on an audio signal input from the outside, and inputs the generated drive signal between the electrodes 22 and 24 of each piezoelectric element 20 in the same phase. When the oscillation device is caused to function as a speaker that directly outputs audible sound, the control unit 50 generates a drive signal by amplifying the audio signal. When the oscillation device functions as a parametric speaker, the control unit 50 modulates audio data (original signal) input from the outside to generate modulation data for the parametric speaker, and generates a drive signal based on this data. To do. The frequency of this drive signal is the nth-order resonance frequency of the piezoelectric element 20.

  Next, the operation and effect of this embodiment will be described. One surface of the piezoelectric element 20 is attached to the bottom surface of the support member 40, and the opposite surface, which is the surface opposite to the one surface, is attached to the vibration member 10. The electrodes 22 and 24 apply a voltage between one surface and the opposite surface of the piezoelectric element 20. Further, the end of the vibration member 10 is not constrained. For this reason, when the drive signal of the piezoelectric element 20 is input between the electrodes 22 and 24, the whole vibration member 10 vibrates up and down. Therefore, the output of the oscillation device can be increased.

(Second Embodiment)
FIG. 3 is a diagram illustrating a configuration of the electronic device according to the second embodiment. The electronic device according to the present embodiment has an oscillation device inside the housing 60. The configuration of the oscillation device is the same as that of the first embodiment except for the shape of the support member 40.

  In the present embodiment, the support member 40 does not have a box shape. The vibrating member 10 faces a sound hole 62 provided in the housing 60. For this reason, the sound wave generated by the vibrating member 10 is radiated to the outside through the sound hole 62.

  Also according to this embodiment, the same effect as that of the first embodiment can be obtained.

(Third embodiment)
FIG. 4 is a diagram illustrating a configuration of the oscillation device according to the third embodiment. The oscillation device according to the present embodiment is the same as the oscillation device according to the first embodiment except that the piezoelectric element 20 is also provided at the center of the vibration member 10. In the electronic apparatus according to the second embodiment, the piezoelectric element 20 may be provided at the center of the vibration member 10.

  Also according to this embodiment, the same effect as that of the first embodiment can be obtained. Further, since the piezoelectric element 20 is also provided at the center of the vibration member 10, it is possible to suppress the vibration member 10 from being bent during vibration.

(Fourth embodiment)
FIG. 5 is a diagram illustrating a configuration of the oscillation device according to the fourth embodiment. The oscillation device according to the present embodiment is the same as the oscillation device according to the first embodiment except that the vibration member 10 includes a spring member 12.

  In this embodiment, the spring member 12 is a plate spring formed by bending at least a part of the edge of the vibration member 10. The spring member 12 is provided on each of the plurality of piezoelectric elements 20. That is, the vibration member 10 is bonded to the plurality of piezoelectric elements 20 via the spring member 12. The shape of the spring member 12 is not limited to the above example, and may be a coil spring that is separate from the vibration member 10. The basic resonance frequency of the spring member 12 preferably matches the basic resonance frequency of the piezoelectric element 20.

  Also according to this embodiment, the same effect as that of the first embodiment can be obtained. Further, since the spring member 12 is provided between the vibration member 10 and the piezoelectric element 20, the vibration of the vibration member 10 can be further increased. Therefore, the output of the oscillation device can be further increased.

(Fifth embodiment)
FIG. 6 is a diagram illustrating the configuration of the oscillation device according to the fifth embodiment. The oscillation device according to the present embodiment is the same as the oscillation device according to the first embodiment, except that the piezoelectric element 20 is mounted on the bottom surface of the support member 40 via the spring member 70.

  In the present embodiment, the spring member 70 is a leaf spring in which an end portion of a metal plate is bent. Each of the plurality of piezoelectric elements 20 is provided on the bent end. In addition, a sheet-like portion of the spring member 70 that is not a plate spring (that is, a central portion of the metal plate) is fixed to the bottom surface of the support member 40. The basic resonance frequency of the spring member 70 preferably matches the basic resonance frequency of the piezoelectric element 20.

  Also according to this embodiment, the same effect as that of the first embodiment can be obtained. Further, since the spring member 70 is provided between the piezoelectric element 20 and the support member 40, the vibration of the vibration member 10 can be further increased. Therefore, the output of the oscillation device can be further increased.

(Sixth embodiment)
FIG. 7 is a cross-sectional view showing the configuration of the oscillation device according to the sixth embodiment. The oscillation device according to the present embodiment includes a support member 40, a vibration member 10 (first vibration member), a piezoelectric element 20, a second vibration member 30, and a first fixing member 32. In the present embodiment, the support member 40 has a bottom portion 42 and side portions 44. The vibration member 10 is disposed above the bottom portion 42 and has an edge facing the side portion 44. The second vibration member 30 connects the edge of the vibration member 10 and the side portion 44 and is formed of a material that is more flexible than the vibration member 10. In the example shown in the drawing, the second vibrating member 30 is fixed to the upper end of the side portion 44. The first fixing member 32 has one end attached to the second vibrating member 30 and the other end fixed to the bottom 42. The distance from the first fixing member 32 to the side portion 44 is greater than the distance from the first fixing member 32 to the end of the vibration member 10.

  The configuration of the vibration member 10 is the same as that of the first embodiment. The material of the piezoelectric element 20 is the same as that in the first embodiment. The second vibrating member 30 is formed of a resin such as polyethylene, urethane, or polyethylene terephthalate. The first fixing member 32 is made of a resin such as polyethylene, urethane, or polyethylene terephthalate.

  In the example illustrated in FIG. 7, the second vibrating member 30 is formed only between the side portion 44 and the outer peripheral portion of the vibrating member 10, and does not extend to the central portion of the vibrating member 10. However, as shown in FIG. 8, the second vibrating member 30 may extend to the center of the vibrating member 10.

  FIG. 9 is a plan view of the oscillation device shown in FIG. As shown in the figure, the planar shapes of the piezoelectric element 20 and the vibration member 10 are circular and are arranged so as to be concentric with each other. The vibrating member 10 is larger than the piezoelectric element 20. Further, the side portion 44 of the support member 40 also has a shape along the circumference, and is disposed so as to be concentric with the vibration member 10 and the piezoelectric element 20. The second vibrating member 30 is formed by a plurality of beams. These beams are located on a straight line extending radially from the center of the vibration member 10 and are arranged at equal intervals in the circumferential direction. In the example shown in this figure, the number of beams constituting the second vibrating member 30 is four, and they are arranged at intervals of 90 °.

  In addition, the planar shape of the side part 44 does not need to be circular. For example, as shown in FIG. 10, the side part 44 may have a shape along four sides of a rectangle, for example, a square.

  FIG. 11 is a diagram illustrating an example in which the oscillation device illustrated in FIGS. 7 to 9 is arranged in a housing 60 of an electronic device. In the example shown in this figure, the vibrating member 10 faces a sound hole 62 provided in the housing 60. For this reason, the sound wave generated by the vibrating member 10 is radiated to the outside through the sound hole 62.

  Next, the operation and effect of this embodiment will be described. In the present embodiment, the oscillation member includes the vibration member 10 and the second vibration member 30. When the Kudo signal is input to the piezoelectric element 20, the vibrating member 10 and the second vibrating member 30 oscillate the sonic wave. Here, the second vibrating member 30 is formed of a material softer than the vibrating member 10. The second vibrating member 30 and the bottom 42 are connected by the first fixing member 32. Therefore, the vibration generated in the second vibrating member 30 is increased by the effect of the insulator caused by the first fixing member 32. Accordingly, the output of the oscillation device is increased.

  The first fixing member 32 is made of resin. That is, the first fixing member 32 also functions as a spring member. That is, the vibration generated in the second vibrating member 30 is increased by the function of the first fixing member 32 as a spring. Accordingly, the output of the oscillation device is increased. Further, when the second vibrating member 30 and the first fixing member 32 are made of resin, even when an electronic device having an oscillation device falls, the impact caused by the dropping is caused by the second vibrating member 30 and the first fixing member 32. Absorbed. Therefore, the impact resistance of the electronic device is improved. In order to obtain this effect, the first fixing member 32 may be another spring member such as a coil spring or a leaf spring.

  Further, when the transmitting device functions as a speaker that outputs an audible sound as it is, it is preferable that the mechanical quality factor Q of the vibrating member is low because the frequency dependence of the sound pressure is low. On the other hand, when the second vibrating member 30 is made of a material having a larger internal loss than the vibrating member 10, for example, a resin, the mechanical quality factor Q of the vibrating member including the vibrating member 10 and the second vibrating member 30 is lowered. can do.

(Seventh embodiment)
FIG. 12 is a plan view showing the configuration of the oscillation device according to the seventh embodiment, and corresponds to FIG. 9 in the sixth embodiment. The oscillation device according to the present embodiment has the same configuration as that of the oscillation device according to the sixth embodiment except for the following points.

  First, the second vibrating member 30 has a ring-shaped portion in addition to the beam-shaped member. This ring-shaped part is located on the side part 44. The ring portion of the second vibrating member 30 is wider than the side portion 44 and protrudes toward the inner peripheral side of the side portion 44 in plan view. A ring-shaped first fixing member 32 is joined to the protruding portion.

  Also in this embodiment, the same effect as that in the sixth embodiment can be obtained.

(Eighth embodiment)
FIG. 13 is a diagram illustrating the configuration of the oscillation device according to the eighth embodiment. The oscillation device according to the present embodiment has the same configuration as that of the oscillation device according to the sixth embodiment, except that the piezoelectric elements 20 are provided on both surfaces of the vibration member 10. A driving signal is input to the piezoelectric element 20 from the control unit 50. The control unit 50 controls the signals input to the two piezoelectric elements 20 to cause the oscillation device shown in FIG. 12 to function as a bimorph type oscillation device.

  Also in this embodiment, the same effect as that in the sixth embodiment can be obtained.

(Ninth embodiment)
FIG. 14 is a diagram illustrating a configuration of the oscillation device according to the ninth embodiment. The oscillation device according to the present embodiment has the same configuration as that of the oscillation device according to the sixth embodiment except for the following points.

  First, the vibration member 10 and the second vibration member 30 are separated from each other in the direction along the side portion 44 of the support member 40. In addition, the vibration member 10 and the second vibration member 30 overlap each other at the outer peripheral portion of the vibration member 10. A second fixing member 34 is provided at a portion where the vibration member 10 and the second vibration member 30 overlap each other. The second fixing member 34 connects the vibration member 10 and the second vibration member 30 to each other. The second fixing member 34 has a ring shape and is disposed so as to be concentric with the vibration member 10. The second fixing member 34 is formed of a resin material such as polyethylene, urethane, or polyethylene terephthalate.

  Also according to this embodiment, the same effect as that of the first embodiment can be obtained. Moreover, since the 2nd fixing member 34 is formed with the resin material, the 2nd fixing member 34 functions as a spring, and thereby the vibration of the vibration member 10 is amplified. Therefore, the output of the oscillation device is further increased.

(Tenth embodiment)
FIG. 15 is a diagram illustrating a configuration of the oscillation device according to the tenth embodiment. The oscillation device according to the present embodiment is the same as the oscillation device according to the ninth embodiment except that the side portion 44 is formed of a material having higher flexibility than the bottom portion 42 (a material that easily functions as a spring). It is the same composition. When the side portion 44 is formed of stainless steel, brass, or polypropylene, the bottom portion 42 is formed of a resin material such as polyethylene, urethane, or polyethylene terephthalate.

  Also in this embodiment, the same effect as that of the ninth embodiment can be obtained. Further, since the side portion 44 is formed of a material that functions more easily as a spring than the bottom portion 42, the side portion 44 functions as a spring member. For this reason, the amplitude of the vibration member 10 and the second vibration member 30 can be further increased. Therefore, the output of the oscillation device is further increased.

  As mentioned above, although embodiment of this invention was described with reference to drawings, these are the illustrations of this invention, Various structures other than the above are also employable.

DESCRIPTION OF SYMBOLS 10 Vibration member 12 Spring member 20 Piezoelectric element 22 Electrode 24 Electrode 30 2nd vibration member 32 1st fixing member 34 2nd fixing member 40 Support member 42 Bottom part 44 Side part 46 Sound hole 50 Control part 60 Case 62 Sound hole 70 Spring Element

Claims (9)

A support member;
A vibration member disposed above the support member;
A piezoelectric element, wherein one surface is attached to the support member, and an opposite surface that is a surface opposite to the one surface is attached to the vibration member;
An electrode for applying a voltage between the one surface and the opposite surface of the piezoelectric element;
An oscillation device comprising: The oscillation device according to claim 1,
In plan view, the piezoelectric element is smaller than the vibrating member,
An oscillation device in which a plurality of the piezoelectric elements are provided apart from each other in plan view. The oscillation device according to claim 1 or 2,
An oscillation device further comprising a spring member disposed between the vibration member and the piezoelectric element. The oscillation device according to claim 1 or 2,
An oscillation device further comprising a spring member disposed between the support member and the piezoelectric element. A support member having a bottom and sides,
A first vibration member disposed above the bottom of the support member and having an edge facing the side of the support member;
A piezoelectric element attached to the first vibrating member;
A second vibrating member that connects the edge of the first vibrating member and the side of the support member, and is formed of a material that is more flexible than the first vibrating member;
A first fixing member having one end attached to the second vibrating member and the other end fixed to the bottom of the support member;
An oscillation device comprising: The oscillation device according to claim 5,
The oscillation device in which the first fixing member is formed of a resin material. The oscillation device according to claim 5 or 6,
The first vibration member and the second vibration member are separated from each other in a direction along the side portion of the support member;
The first vibrating member and the second vibrating member overlap at an edge of the first vibrating member,
An oscillation device further comprising a second fixing member provided in a portion where the first vibration member and the second vibration member overlap each other, and connecting the first vibration member and the second vibration member. The oscillation device according to any one of claims 5 to 7,
An oscillation device in which the side portion of the support member functions as a spring. The electronic device which has an oscillation apparatus as described in any one of Claims 1-8.

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