JP2015088908A - Electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic apparatus capable of transmitting information on a voice having small distortion.SOLUTION: An electronic apparatus includes: a piezoelectric element 14 which has a long shape in a first direction and which is bent and vibrated so that amplitude changes in the first direction; a panel 12 on which the piezoelectric element 14 is mounted and which vibrates together with the piezoelectric element 14; and a housing 19 on which the panel 12 is mounted and which vibrates together with the panel 12. The housing 19 is different between a mass on one side in a first direction and a mass on the other side in the first direction. The electronic apparatus capable of transmitting information on a voice having small distortion can be obtained.

Description

  The present invention relates to an electronic device.

  2. Description of the Related Art Conventionally, an electronic device that vibrates a diaphragm by fixing a plate-like piezoelectric bimorph element to the diaphragm and vibrating the piezoelectric bimorph element is known (for example, see Patent Document 1).

JP 2006-238072 A

  However, in the above-described conventional electronic device, the amplitude of the diaphragm changes abruptly at a specific frequency, and when voice information is transmitted by vibration of the diaphragm, the transmitted voice information is distorted. There was a problem.

  The present invention has been devised in view of such problems in the prior art, and an object of the present invention is to provide an electronic device capable of transmitting audio information with low distortion.

  An electronic device according to the present invention has a shape that is long in a first direction, and a piezoelectric element that bends and vibrates so that the amplitude changes in the first direction, together with the piezoelectric element to which the piezoelectric element is attached. A panel that vibrates, and a housing that is attached to the panel and vibrates with the panel, wherein the housing has a mass on one side in the first direction and the other side in the first direction. The mass is different from each other.

  According to the electronic device of the present invention, it is possible to obtain an electronic device capable of transmitting audio information with small distortion.

It is a perspective view which shows typically the electronic device of the 1st example of embodiment of this invention. It is a perspective view for demonstrating the structure of the electronic device shown in FIG. It is a perspective view for demonstrating the structure of the electronic device shown in FIG. FIG. 2 is a cross-sectional view taken along line A-A ′ in FIG. 1. FIG. 2 is a sectional view taken along line B-B ′ in FIG. 1. It is the C-C 'sectional view taken on the line in FIG. It is a perspective view which shows typically the electronic device of the 2nd example of embodiment of this invention. FIG. 8 is a perspective view for explaining the structure of the electronic device shown in FIG. 7. FIG. 8 is a cross-sectional view taken along line E-E ′ in FIG. 7.

  Hereinafter, an electronic device of the present invention will be described in detail with reference to the accompanying drawings.

(First example of embodiment)
FIG. 1 is a perspective view schematically showing an electronic apparatus which is a first example of an embodiment of the present invention. FIG. 2 is a perspective view schematically showing the structure of the housing 19 in the electronic apparatus shown in FIG. FIG. 3 is a perspective view schematically showing the panel 12 and the piezoelectric element 14 and the display 18 attached to the panel 12 in the electronic apparatus shown in FIG. 4 is a cross-sectional view taken along line AA ′ in FIG. 5 is a cross-sectional view taken along line BB ′ in FIG. 6 is a cross-sectional view taken along the line CC ′ in FIG. As shown in FIGS. 1 to 6, the electronic apparatus of this example includes a panel 12, a piezoelectric element 14, a display 18, and a housing 19.

  The piezoelectric element 14 has a shape that is long in the x-axis direction. Specifically, the piezoelectric element 14 has a rectangular parallelepiped shape in which the x-axis direction is the length direction, the y-axis direction is the width direction, and the z-axis direction is the thickness direction. The piezoelectric element 14 is a laminate formed by laminating a plurality of polarized piezoelectric layers and a plurality of electrode layers in the z-axis direction. In the z-axis direction, the electrode layers and the piezoelectric layers are alternately arranged.

  The piezoelectric element 14 is configured such that the direction of polarization with respect to the direction of the electric field applied at a certain moment is reversed between one side and the other side in the z-axis direction. Therefore, for example, when an electric signal is applied and one side in the z-axis direction extends in the x-axis direction at a certain moment, the other side in the thickness direction of the piezoelectric element 14 is contracted in the x-axis direction. As described above, the piezoelectric element 14 has a bimorph structure and bends and vibrates in the z-axis direction so that the amplitude changes in the x-axis direction when an electric signal is applied.

  For example, the piezoelectric element 14 has a length of about 15 mm to 40 mm, a width of about 1 mm to 6 mm, and a thickness of about 0.2 mm to 1.0 mm. As the piezoelectric layer constituting the piezoelectric element 14, for example, a lead-free piezoelectric material such as lead titanate (PT), lead zirconate titanate (PZT), Bi layered compound, tungsten bronze structure compound, or the like is preferably used. However, other piezoelectric materials may be used. The thickness of one layer of the piezoelectric layer can be set to about 0.01 to 0.1 mm, for example. The electrode layer constituting the piezoelectric element 14 can be preferably formed using, for example, a ceramic component or a glass component in addition to a metal component such as silver or an alloy of silver and palladium. You may form using another known metal material.

  Such a piezoelectric element 14 can be manufactured by the following method, for example. First, a binder, a dispersant, a plasticizer, and a solvent are added to the piezoelectric material powder, and the mixture is agitated to produce a slurry. The obtained slurry is formed into a sheet shape to produce a green sheet. Next, a conductive paste is printed on the green sheet to form an electrode layer pattern, and the green sheet on which the electrode layer pattern is formed is laminated to produce a laminated molded body, which is then degreased and fired to a predetermined size. A laminated body is obtained by cutting. Next, a conductive paste for forming a surface electrode is printed and baked at a predetermined temperature, and then a direct current voltage is applied through the electrode layer to polarize the piezoelectric layer. In this way, the piezoelectric element 14 can be obtained.

  The piezoelectric element 14 only needs to have a function of bending vibration based on the input electrical signal. The piezoelectric element 14 may be, for example, a unimorph type piezoelectric element.

The panel 12 has a rectangular thin plate shape. A piezoelectric element 14 is attached to the surface of the panel 12 in the −z direction. In addition, the panel 12 is attached to the housing 19 only at the periphery of the surface in the −z direction, and is attached to the housing 19 so as to vibrate. The panel 12 vibrates together with the piezoelectric element 14 when the piezoelectric element 14 vibrates. Such a panel 12 can be preferably formed using a material having high rigidity and elasticity, such as acrylic resin or glass, but may be formed using other materials. Moreover, the thickness of the panel 12 is set to about 0.4 mm-1.5 mm, for example. A known joining member such as a double-sided tape or an adhesive can be used for joining the panel 12 and the piezoelectric element 14 or joining the panel 12 and the housing 19. The panel 12 may have an input device such as a touch panel.

  The display 18 is a display device having a function of displaying image information. For example, a known display such as a liquid crystal display, a plasma display, and an organic EL display can be suitably used. The display 18 may have an input device such as a touch panel.

  The display 18 is attached to the surface of the panel 12 in the −z direction and integrated with the panel 12. That is, the panel 12 functions as a cover that protects the display 18. The display 18 may be attached to the housing 19. Further, the display 18 is not always necessary and may be omitted.

  The housing 19 has a box shape with one surface opened, and the periphery of the panel 12 is joined to the opening. In this way, the casing 19 forms the outer shape of the electronic device together with the panel 12 and functions as a support that supports the panel 12 so as to vibrate. And the housing | casing 19 vibrates with the panel 12 when the panel 12 vibrates. Such a casing 19 can be formed preferably using a material such as a synthetic resin having high rigidity and elasticity, but may be formed using other materials.

  In the electronic apparatus of this example having such a configuration, an electrical signal having audio information is input to the piezoelectric element 14 from an electronic circuit (not shown), and the piezoelectric element 14 bends and vibrates based on the electrical signal. The panel 12 and the housing 19 are flexibly vibrated by the flexural vibration of the piezoelectric element 14. Therefore, voice information can be transmitted to the human body by bringing the panel 12 or the casing 19 into contact with the human body.

  In addition, the electronic apparatus of the present example includes a first portion 21 that is a portion thicker than other portions of the housing 19 on the −x direction side of the housing 19. Since the housing 19 has the first portion 21, the mass of the housing 19 on the −x direction side is larger than the mass of the housing 19 on the + x direction side. That is, the mass on one side (−x direction side) of the housing 19 in the x-axis direction is different from the mass on the other side (+ x direction side) of the housing 19 in the x-axis direction. Thereby, in the flexural vibration of the panel 12 and the housing 19, an abrupt increase in amplitude at a specific frequency can be reduced, so that an electronic device capable of transmitting an audio signal with small distortion can be obtained. The reason why this effect can be obtained is presumed that the level of the peak due to resonance in the frequency characteristic of the sound pressure of the electronic device is reduced due to a decrease in symmetry in the bending vibration of the housing 19. Note that the −x direction side of the housing 19 means the −x direction side of the center of the housing 19 in the x-axis direction (shown by the DD ′ line in FIGS. 6 and 9). + X direction side means the + x direction side of the center of the housing 19 in the x-axis direction (indicated by the DD ′ line in FIGS. 6 and 9). In addition, since the piezoelectric element 14 bends and vibrates so that the amplitude changes in the x-axis direction, the panel 12 and the housing 19 also flexurally vibrate so that the amplitude changes in the x-axis direction. It is presumed that the above-described effects can be obtained by the decrease in the above.

  The thickness of the first portion 21 is preferably 1.5 times or more of the thickness of the other portions, more preferably 2 times or more. However, the thickness and width of the first portion 21 are desired. It can be set as appropriate depending on the magnitude of the effect. The position of the first portion 21 is not limited to the position shown in FIG. 2 and may be another position. A plurality of first portions 21 may be provided. For example, the first portion 21 may be formed over the entire −x direction side of the housing 19.

  Moreover, in the electronic device of this example, although the case where the 1st part 21 was a part thicker than another part was shown, it is not limited to this. For example, the first portion 21 may be a portion formed of a material having a higher density than other portions.

(Second example of embodiment)
FIG. 7 is a perspective view schematically showing an electronic apparatus according to a second example of the embodiment of the present invention. FIG. 8 is a perspective view schematically showing the structure of the housing 19 in the electronic apparatus shown in FIG. 9 is a cross-sectional view taken along line EE ′ in FIG. In this example, points different from the first example of the above-described embodiment will be described, and the same components are denoted by the same reference numerals, and redundant description will be omitted.

  In the electronic apparatus of this example, the second portion 22, which is a portion thinner than the other portions of the housing 19, is provided on the + x direction side of the housing 19. Since the housing 19 includes the second portion 22, the mass of the housing 19 on the + x direction side is smaller than the mass of the housing 19 on the −x direction side. That is, the mass on one side (−x direction side) of the housing 19 in the x-axis direction is different from the mass on the other side (+ x direction side) of the housing 19 in the x-axis direction. As a result, similar to the electronic device of the first example of the above-described embodiment, a sharp increase in amplitude at a specific frequency can be reduced in the flexural vibration of the panel 12 and the housing 19. An electronic device capable of transmitting a small audio signal can be obtained.

  The thickness of the second portion 22 is desirably 2/3 or less of the thickness of the other portions, and more desirably 1/2 or less. However, the thickness and width of the second portion 22 are desired. It can be set as appropriate depending on the magnitude of the effect. The position of the second portion 22 is not limited to the position shown in FIG. 8, and may be another position. A plurality of second portions 22 may be provided. For example, the second portion 22 may be formed over the entire + x direction side of the housing 19.

  Moreover, in the electronic device of this example, although the case where the 2nd part 22 was a part thinner than another part was shown, it is not limited to this. For example, the second portion 22 may be a portion formed of a material having a lower density than other portions.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and improvements can be made without departing from the scope of the present invention.

  For example, in the first example of the above-described embodiment, an example is shown in which the casing 19 has the first portion 21 on the −x direction side that is thicker than the other portions. In the example of 2, the case 19 has the example in which the casing 19 has the second portion 22 having a smaller thickness than the other portions on the + x direction side, but is not limited thereto. For example, the housing 19 has at least one first portion 21 having a thickness larger than that of the other portion on the −x direction side, and has a second portion 22 having a thickness smaller than that of the other portion on the + x direction side. You may make it have one or more.

12: Panel 14: Piezoelectric element 19: Housing 21: First part 22: Second part

Claims (4)

A piezoelectric element having a long shape in the first direction, and bending and oscillating so that the amplitude changes in the first direction;
A panel to which the piezoelectric element is attached and vibrates with the piezoelectric element;
The panel is attached and has a housing that vibrates with the panel;
The electronic device according to claim 1, wherein a mass of one side in the first direction is different from a mass of the other side in the first direction.   The electronic apparatus according to claim 1, wherein the casing has a portion thicker than the other portion on one side in the first direction.   3. The electronic device according to claim 1, wherein the casing has a portion having a thickness smaller than that of the other portion on the other side in the first direction.   4. The electronic apparatus according to claim 1, wherein the panel is brought into contact with a human body to transmit voice information to the human body.

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