Panel speaker

Abstract

A panel-type loudspeaker includes a panel and an actuator, and the panel-type loudspeaker is configured to vibrate the panel through the actuator so as to output sound waves from the panel. The actuator includes a diaphragm and a piezoelectric element, and the piezoelectric element is disposed on at least one surface of the diaphragm; the piezoelectric element has an opening at a central portion of the piezoelectric element in a plan view, the diaphragm is exposed from the opening, and at a portion of the diaphragm exposed from the opening, the diaphragm is coupled to the panel.

Description

Technical Field

[0001] The present invention relates to a panel type speaker. Background Art

[0002] A display speaker (panel type speaker) is known, in which a display panel of a display is used as a speaker by vibrating the display panel using an actuator (vibration actuator) incorporating a piezoelectric element. In the display speaker, a vibration transmission unit is provided between the vibration actuator and the display panel. The vibration transmission unit is attached to the rear surface of the display panel by, for example, double-sided tape or the like. Further, the vibration transmission unit is attached to the central portion of the piezoelectric element of the vibration actuator by, for example, double-sided tape or the like. Therefore, the vibration transmission unit can transmit the vibration of the vibration actuator to the display panel.

[0003] JP-A-2010-171927 discloses a conventional speaker. Summary of the Invention

[0004] When the piezoelectric element of the vibration actuator attached to the vibration transmission unit vibrates, stress may be applied to the piezoelectric element, resulting in damage to the piezoelectric element.

[0005] Further, when the display panel is vibrated by the vibration actuator, due to resonance between the vibration actuator and the display panel, the sound pressure at a specific frequency (resonance frequency) may become strong. As a display speaker, it is desirable to obtain appropriate frequency characteristics over the entire output frequency band rather than having a prominent part of the frequency. However, the resonance frequency is ultimately determined by peripheral structures such as the size of the vibration actuator, the size of the display panel, and the housing of the display panel, and it is difficult to arbitrarily adjust the resonance frequency.

[0006] A first object of the present invention is to provide a panel type speaker that reduces damage to the piezoelectric element.

[0007] A second object of the present invention is to provide a technique capable of appropriately setting the resonance frequency of the actuator.

[0008] To achieve the first object, according to a first aspect of the present invention, there is provided a panel type speaker including a panel and an actuator, and the panel type speaker is configured to vibrate the panel by the actuator to output sound waves from the panel, the actuator including a diaphragm and a piezoelectric element disposed on at least one surface of the diaphragm; wherein the piezoelectric element has an opening at a central portion of the piezoelectric element in a plan view, the diaphragm is exposed from the opening, and at a portion of the diaphragm exposed from the opening, the diaphragm is coupled to the panel.

[0009] To achieve the second object, according to a second aspect of the present invention, there is provided a panel type speaker including a panel and an actuator, and the panel type speaker is configured to vibrate the panel by the actuator to output sound waves from the panel. The speaker includes a vibration transmission unit and a constraint unit. The vibration transmission unit has one end connected to the panel and the other end connected to the actuator, and the vibration transmission unit is configured to transmit the vibration of the actuator to the panel. The constraint unit is configured to constrain the actuator to the vibration transmission unit. Wherein, the actuator includes a diaphragm and a piezoelectric element, and the piezoelectric element is disposed on at least one surface of the diaphragm. Wherein, the length of a part of the constraint unit along a specific direction is set to a predetermined length such that the resonance frequency of the bending vibration propagating in the specific direction in the plane of the diaphragm becomes a predetermined frequency.

[0010] According to a first aspect of the present invention, a panel type speaker that reduces damage to the piezoelectric element can be provided.

[0011] According to a second aspect of the present invention, a technique capable of appropriately setting the resonance frequency of the actuator can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a view showing a configuration example of the display speaker 10 of the first embodiment.

[0013] Figure 2 is a view showing a configuration example of the vibration actuator 300 of the first embodiment.

[0014] Figure 3 is a view showing a configuration example of the display speaker 11 of the first modification.

[0015] Figure 4 is a view showing a configuration example of the vibration actuator 300 of the first modification.

[0016] Figure 5 is a view showing a configuration example of the display speaker 12 of the second modification.

[0017] Figure 6 is a view showing a configuration example of the vibration actuator 300 of the second modification.

[0018] Figure 7 is a view showing a configuration example of the vibration actuator 300 of the third modification.

[0019] Figure 8 is a view showing a configuration example of the display speaker 13 of the fourth modification.

[0020] Figure 9 This is a view showing a structural example of the vibration actuator 300 of the fourth modification.

[0021] Figure 10 This is a view showing a structural example of the display speaker of the second embodiment.

[0022] Figure 11 This is a view of the actuator as observed from the display side (front surface side).

[0023] Figure 12 This is a view of the actuator as observed from the rear surface side.

[0024] Figure 13 This is an exploded perspective view of the vibration actuator.

[0025] Figure 14 This is a view showing the structure of the display speaker according to the fifth modification.

[0026] Figure 15 This is a view showing the structure of the display speaker according to the sixth modification.

[0027] Figure 16 This is a view of the vibration transmission unit according to the sixth modification as observed from the actuator side.

[0028] Figure 17 This is a view showing the structure of the display speaker according to the seventh modification.

[0029] Figure 18 This is a view of the vibration transmission unit according to the seventh modification as observed from the actuator side.

[0030] Figure 19 This is a view showing the structure of the display speaker according to the third embodiment.

[0031] Figure 20 This is a view of the display speaker according to the third embodiment as observed from the rear surface side.

[0032] Figure 21 This is a view showing the structure of the display speaker according to the eighth modification.

[0033] Figure 22 This is a view of the display speaker according to the eighth modification as observed from the rear surface side. Detailed Description of the Invention

[0034] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The structures of the following embodiments are shown by way of example, and thus the present invention is not limited to the structures of these embodiments.

[0035] A panel - type speaker will be described in this text. In this panel - type speaker, a panel is vibrated by an actuator to output sound waves from the panel. In the following embodiments, the case where a vibration actuator is provided on a display panel of a display and thus the display functions as a display speaker will be mainly described. A display speaker is a device that can output (emit) sound waves from a display panel by vibrating the display panel using a vibration actuator (actuator).

[0036] <First Embodiment>

[0037] (Example of Structure)

[0038] Figure 1 FIG. is a view showing an example of the structure of the display speaker 10 of this embodiment. Figure 1 FIG. is a cross - sectional view of the display speaker 10 as viewed from above. Figure 1 The display speaker 10 includes a display panel 100, a vibration transmission unit 200, and a vibration actuator 300. The vibration transmission unit 200 includes a body portion 210, a double - sided tape 221, and a double - sided tape 222. The double - sided tape 221 is on the side of the body portion 210 facing the display panel, and the double - sided tape 222 is on the side of the body portion 210 facing the vibration actuator. The vibration actuator 300 includes a diaphragm 310, a piezoelectric element 320, and a piezoelectric element 330. The piezoelectric element 320 is attached to the surface of the diaphragm 310 facing the display panel (referred to as the first surface), and the piezoelectric element 330 is attached to the surface of the diaphragm 310 opposite to the first surface (referred to as the second surface). A plurality of vibration transmission units 200 and vibration actuators 300 can be attached to one display panel 100. Here, the direction from Figure 1 right to left in FIG. is referred to as the x - direction, the direction from Figure 1 the back surface to the front surface of the paper surface of FIG. is referred to as the y - direction, and the direction from Figure 1 the bottom to the top in FIG. (the direction from the vibration actuator 300 to the display panel 100) is referred to as the z - direction. The positional relationship between the display speaker 10 and the x - direction, y - direction, and z - direction is similarly applied to other drawings. The display panel 100 is an example of a panel. The display speaker is an example of a panel - type speaker. The vibration actuator 300 is an example of an actuator.

[0039] The display panel 100 is a display panel included in a liquid - crystal monitor, an organic EL (electroluminescence) display, etc.

[0040] The vibration transmission unit 200 is configured to transmit the vibration of the vibration actuator 300 to the display panel 100. For example, the main body portion 210 of the vibration transmission unit 200 is a columnar object (e.g., a quadrangular column, a cylinder, etc.) and has upper and lower surfaces that are substantially parallel to each other. For example, the vibration transmission unit 200 is made of resin, metal, etc. A double-sided tape 221 is attached to one of the upper and lower surfaces, and a double-sided tape 222 is attached to the other surface. Here, it is assumed that the double-sided tape 221 is attached to the upper surface and the double-sided tape 222 is attached to the lower surface. The double-sided tape 221 is configured to attach and fix the main body portion 210 of the vibration transmission unit 200 to the rear surface of the display panel 100. The double-sided tape 222 is configured to attach and fix the main body portion 210 of the vibration transmission unit 200 to the vibration plate 310 of the vibration actuator 300. The vibration transmission unit 200 is fixed to the vibration plate 310 without contacting the piezoelectric element 320. The vibration transmission unit 200 is fixed between the display panel 100 and the vibration actuator 300 by the double-sided tapes 221, 222. Instead of the double-sided tapes 221, 222, an adhesive or the like can be used. The vibration transmission unit 200 and the display panel 100 can be integrated into one body. The vibration plate 310 of the vibration actuator 300 is coupled to the display panel 100 via the vibration transmission unit 200.

[0041] The diaphragm 310 of the vibration actuator 300 is a rectangular plate-like member and has a front surface (first surface) and a rear surface (second surface) extending in a direction orthogonal to the thickness direction of the diaphragm 310. The shape of the diaphragm 310 may be circular or elliptical. In addition, the shape of the diaphragm 310 may have other shapes as long as the diaphragm 310 is symmetric in the horizontal and vertical directions. The front surface is substantially parallel to the rear surface. In addition, the diaphragm 310 is arranged such that the front surface of the diaphragm 310 is substantially parallel to the rear surface of the display panel 100. The piezoelectric elements 320 and 330 are elements configured to deform in response to a voltage applied thereto when a voltage is applied thereto. The piezoelectric elements 320 and 330 are made of a plate-like material (e.g., ceramic) that exhibits the piezoelectric effect. The piezoelectric elements 320 and 330 have electrodes for applying a voltage to which the piezoelectric elements are attached. The piezoelectric element 320 is attached to the first surface of the diaphragm 310. The piezoelectric element 330 is attached to the second surface of the diaphragm 310. The piezoelectric element 320 has an opening formed to expose the central portion of the diaphragm 310 as viewed from the first surface side. The piezoelectric element 320 has an opening in the central portion of the piezoelectric element. The diaphragm 310 has a portion (exposed portion) exposed at the central portion of the first surface of the diaphragm 310 through the opening of the piezoelectric element 320. The double-sided tape 222 on the vibration transmission unit 200 is attached to the opening such that the diaphragm 310 and the vibration transmission unit 200 are attached to each other. At this time, the piezoelectric element 320 and the vibration transmission unit 200 do not contact each other. On the other hand, the piezoelectric element 330 may not be attached to the diaphragm 310 (alternatively, the piezoelectric element 330 may not be provided). The first surface and the second surface are in the x-y plane.

[0042] Figure 2 is a view showing a structural example of the vibration actuator 300 of the present embodiment. Figure 2is a view of the vibration actuator 300 as viewed from the first surface side. A piezoelectric element 320 having an opening is attached to the first surface of a vibration plate 310 of the vibration actuator 300. Further, a central portion of the vibration plate 310 (a portion including the center of the first surface, the central portion in a plan view) is exposed through the opening of the piezoelectric element 320. Here, if the shape of the vibration plate 310 is rectangular, the center of the first surface (or the second surface) of the vibration plate 310 is the intersection point of the two diagonals of the rectangle. Further, if the shape of the vibration plate 310 is circular or elliptical, the center of the first surface (or the second surface) of the vibration plate 310 is the center of the circle or the ellipse. Even if the vibration plate 310 has any other shape, the center of the first surface (or the second surface) of the vibration plate 310 can be defined by, for example, its center of gravity or the like. The size of the opening of the piezoelectric element 320 (the size of the exposed portion of the vibration plate 310) is larger than the size of the body portion 210 of the vibration transmission unit 200 attached to the lower surface of the vibration plate 310 ( Figure 2 the portion surrounded by a dashed line in). Thus, the piezoelectric element 320 and the vibration transmission unit 200 do not contact each other. Here, although the shape of the opening of the piezoelectric element 320 is rectangular (or square), the shape of the opening of the piezoelectric element 320 can be circular or the like according to the shape of the vibration transmission unit 200. In order to increase the area of the piezoelectric element 320, it is preferable to make the size of the opening of the piezoelectric element 320 as small as possible. By increasing the area of the piezoelectric element 320, the output (maximum output) of the display speaker 10 can be made larger. Further, when the vibration actuator 300 is viewed from the first surface side, the outer end portion of the piezoelectric element 320 is preferably positioned within the end portion of the vibration plate 310. If the outer end portion of the piezoelectric element 320 is positioned outside the end portion of the vibration plate 310, the piezoelectric element 320 is likely to be damaged. This feature is similarly applied to the piezoelectric element 330 attached to the second surface of the vibration plate 310.

[0043] (First modification)

[0044] Now, a first modification of the present embodiment will be described. Some configurations of the first modification are common to those of the foregoing configuration example. Here, the differences from the foregoing configuration example will be mainly described.

[0045] Figure 3 is a view showing a configuration example of the display speaker 11 of the first modification. Figure 3 is a cross-sectional view of the display speaker 11 as viewed from above. Figure 3The display speaker 11 includes a display panel 100, a vibration transmission unit 200, and a vibration actuator 300. The vibration transmission unit 200 includes a body portion 210, a double-sided tape 221, and a screw 230. The double-sided tape 221 is on a side of the body portion 210 facing the display panel. The vibration actuator 300 includes a diaphragm 310, a piezoelectric element 320, and a piezoelectric element 330. The diaphragm 310 has a through hole at a central portion of the diaphragm. The center of the through hole coincides with the center of the diaphragm 310. For example, the cross-sectional shape of the through hole is circular. The vibration transmission unit 200 and the display panel 100 may be integrated into one body.

[0046] Figure 4 is a view showing a structural example of the vibration actuator 300 of the first modification. Figure 4 is a view of the vibration actuator 300 as viewed from the first surface side. At a central portion of the diaphragm 310 of the vibration actuator 300, a through hole is formed to allow the screw 230 to pass through the through hole. At a central portion of the piezoelectric element 320, an opening is provided to expose the through hole of the diaphragm 310.

[0047] In the foregoing structural example, the vibration transmission unit 200 and the vibration actuator 300 are fixed to each other by the double-sided tape 222. However, in the first modification, the vibration transmission unit 200 and the vibration actuator 300 are fixed to each other by the screw 230. In the first modification, the diaphragm 310 has a through hole at its central portion, and the screw 230 is allowed to pass through the through hole. In addition, similar to the piezoelectric element 320, the piezoelectric element 330 attached to the second surface of the diaphragm 310 has an opening exposing the central portion of the second surface of the diaphragm 310. Further, the body portion 210 of the vibration transmission unit 200 has a threaded hole formed on a side of the body portion 210 facing the vibration actuator 300 and configured to allow the screw 230 to be fixed in the threaded hole. When fixing the vibration actuator 300 to the vibration transmission unit 200, the screw 230 is inserted into the through hole from the second surface side of the diaphragm 310 and then screwed into the body portion 210 of the vibration transmission unit 200 positioned on the first surface side. In other words, the vibration actuator 300 is coupled to the display panel 100 via the vibration transmission unit 200 by the screw 230. Therefore, compared with the case of fixing by the double-sided tape 222, the vibration actuator 300 and the display panel 100 are firmly fixed (coupled) to each other. In addition, compared with the case of fixing by the double-sided tape 222, the durability is increased. Instead of the screw 230, bolts and nuts may be employed.

[0048] (Second modification)

[0049] A second variant of the present embodiment will now be described. Some configurations of the second variant are common to those of the foregoing configuration examples and variants. Differences from the foregoing configuration examples and variants will mainly be described herein.

[0050] Figure 5 is a view showing a configuration example of the display speaker 12 of the second variant. Figure 5 is a cross-sectional view of the display speaker 12 as viewed from above. Figure 5 The display speaker 12 of includes a display panel 100, a vibration transmission unit 200, and a vibration actuator 300. The vibration transmission unit 200 includes a main body portion 210, a double-sided tape 221, and a screw 230. The double-sided tape 221 is on a side of the vibration transmission unit 200 facing the display panel. The vibration actuator 300 includes a diaphragm 310, a piezoelectric element 320, and a piezoelectric element 330. The diaphragm 310 has a through hole in a central portion of the diaphragm. The vibration transmission unit 200 and the display panel 100 may be integrated into one body. Similar to the first variant, the second variant has a configuration in which the vibration transmission unit 200 and the vibration actuator 300 are fixed to each other by the screw 230. In the second variant, a side of the main body portion 210 of the vibration transmission unit 200 facing the vibration actuator 300 has a smaller size so that the area of the piezoelectric element 320 is larger. A side of the main body portion 210 of the vibration transmission unit 200 facing the vibration actuator 300 is set to have a size that allows the screw 230 to be supported on that side. On the other hand, preferably, a side of the main body portion 210 of the vibration transmission unit 200 facing the display panel 100 has a larger size. The reason is that the smaller the area of the attachment surface between the display panel 100 and the vibration transmission unit 200, the greater the possibility that the vibration transmission unit 200 and the display panel 100 will be separated. Here, the main body portion 210 of the vibration transmission unit 200 has a shape such that the main body portion 210 does not contact the piezoelectric element 320. A length in the z direction of a side of the main body portion 210 facing the vibration actuator 300 (a portion of the main body portion 210 that is smaller than the side facing the display panel 100) is longer than the thickness of the piezoelectric element 320 (the length of the piezoelectric element 320 in the z direction). Accordingly, the vibration transmission unit 200 and the piezoelectric element 320 do not contact each other.

[0051] Figure 6 is a view showing a configuration example of the vibration actuator 300 of the second variant. Figure 6 is a view of the vibration actuator 300 as viewed from the first surface side. An exposed portion of the diaphragm 310 of the vibration actuator 300 of the second variant is smaller than an exposed portion of the diaphragm 310 of the first variant. Accordingly, the area of the piezoelectric element 320 of the second variant is larger than the area of the piezoelectric element 320 of the first variant. Therefore, the output (maximum output) of the display speaker 12 can be made larger.

[0052] (Third Variant)

[0053] Now, a third variant of the present embodiment will be described. Some configurations of the third variant are common to those of the foregoing configuration examples and variants. Differences from the foregoing configuration examples and variants will mainly be described herein.

[0054] Figure 7 is a view showing a configuration example of the vibration actuator 300 of the third variant. Figure 7 is a view of the vibration actuator 300 as viewed from the first surface side. In the vibration actuator 300 of the third variant, the piezoelectric element 320 is divided into two piezoelectric elements 320A and 320B. Further, the piezoelectric elements 320A and 320B are attached to the vibration plate 310 in such a manner that the piezoelectric elements 320A and 320B are positioned beside the exposed portion of the vibration plate 310 to which the vibration transmission unit 200 will be attached. The piezoelectric elements 320A and 320B are attached to a portion of the vibration plate 310 other than the exposed portion to which the vibration transmission unit 200 will be attached. Here, although two piezoelectric elements are attached to the first surface of the vibration plate 310, two or more piezoelectric elements may be attached to the first surface of the vibration plate 310. Accordingly, there is no need to provide an opening in the piezoelectric element 320, making the processing of the piezoelectric element 320 easier. Further, this feature is similarly applied to the piezoelectric element 330 to be attached to the second surface of the vibration plate 310.

[0055] (Fourth Variant)

[0056] Now, a fourth variant of the present embodiment will be described. Some configurations of the fourth variant are common to those of the foregoing configuration examples and variants. Differences from the foregoing configuration examples and variants will mainly be described herein.

[0057] Figure 8 is a view showing a configuration example of the display speaker 13 of the fourth variant. Figure 8 is a cross-sectional view of the display speaker 13 as viewed from above. Figure 8The display speaker 13 includes a display panel 100, a vibration transmission unit 200, and a vibration actuator 300. The vibration transmission unit 200 includes a body portion 210, a double-sided tape 221, a first screw 230A, and a second screw 230B. The double-sided tape 221 is on a side of the body portion 210 facing the display panel. The vibration actuator 300 includes a diaphragm 310, a piezoelectric element 320, and a piezoelectric element 330. The diaphragm 310 has a first through hole and a second through hole at a central portion of the diaphragm. The center of the first through hole and the center of the second through hole are located on a straight line extending through the center of the diaphragm 310 and parallel to the x direction. The distance from the center of the first through hole to the center of the diaphragm 310 is equal to the distance from the center of the second through hole to the center of the diaphragm 310. For example, if the distance from the center of the through hole to the center of the diaphragm 310 is shorter than the distance from the center of the through hole to the end portion of the diaphragm 310 closest to the through hole, the through hole is considered to be located at the central portion of the diaphragm 310. In addition, the first through hole and the second through hole are located near the center of the diaphragm 310. The vibration transmission unit 200 and the display panel 100 may be integrated into one body. Similar to the first modification and the second modification, the fourth modification has a configuration in which the vibration transmission unit 200 and the vibration actuator 300 are fixed to each other by the first screw 230A and the second screw 30B. In the fourth modification, the vibration transmission unit 200 and the vibration actuator 300 are fixed to each other by two screws (the first screw 230A and the second screw 230B) in order to suppress the bending vibration (flexural vibration) of the diaphragm 310. Here, it is assumed that a bending vibration occurs in which the x direction of the diaphragm 310 is arcuately bent in the z direction. That is, in Figure 8 , due to the voltage applied to the piezoelectric elements 320, 330, a bending vibration occurs in which the x direction of the diaphragm 310 is arcuately bent in the z direction. That is, the bending vibration propagates in the x direction of the diaphragm 310. Here, a plurality of through holes are provided along the direction in which the bending vibration of the diaphragm 310 propagates. Due to the first through hole and the second through hole located on the straight line extending through the center of the diaphragm 310 and parallel to the x direction, and the first screw 230A and the second screw 230B, the vibration of the diaphragm 310 can be effectively transmitted to the display panel 100. If a bending vibration occurs in which the y direction of the diaphragm 310 is arcuately bent in the z direction, the first through hole and the second through hole of the diaphragm 310 may be provided on a straight line extending through the center of the diaphragm 310 and parallel to the y direction. Alternatively, the vibration transmission unit 200 and the vibration actuator 300 may be fixed to each other by two or more through holes and two or more screws. If the fixing is performed at more positions along the propagation direction of the bending vibration, the vibration modes can be dispersed, and thus the vibration of the diaphragm 310 can be more effectively transmitted to the display panel 100 over a wide band.

[0058] Figure 9It is a view showing a structural example of the vibration actuator 300 of the fourth modification. Figure 9 It is a view of the vibration actuator 300 as viewed from the first surface side. The vibration plate 310 of the vibration actuator 300 of the fourth modification has a first through-hole and a second through-hole on a straight line that extends through the center of the vibration plate 310 and is parallel to the x-direction. The piezoelectric element 320 has an opening formed to expose the first through-hole and the second through-hole.

[0059] (Operations and effects of the embodiment)

[0060] The display speaker 10 of the present embodiment includes a display panel 100, a vibration transmission unit 200, and a vibration actuator 300. The vibration actuator 300 includes a vibration plate 310, a piezoelectric element 320, and a piezoelectric element 330. The vibration transmission unit 200 is fixed to the vibration plate 310 without contacting the piezoelectric elements 320 and 330. According to the display speaker 10, the vibration transmission unit 200 does not contact the piezoelectric elements 320 and 330. Therefore, damage to the piezoelectric elements 320 and 330 can be suppressed as compared with a configuration in which the piezoelectric elements 320 and 330 are in contact with the vibration transmission unit 200. In addition, according to the display speaker 10, the vibration actuator 300 and the vibration transmission unit 200 can be firmly coupled to each other.

[0061] [Second Embodiment]

[0062] (Structural example)

[0063] Figure 10 It is a view showing a structural example of the display speaker 10 of the second embodiment. Figure 10 It is a cross-sectional view of the display speaker 10 as viewed from above, Figure 11 It is a view of the actuator as viewed from the display side (front surface side), Figure 12 It is a view of the actuator as viewed from the rear surface side, and Figure 13 It is an exploded perspective view of the vibration transmission unit 200. Figure 10 The display speaker 10 includes a display panel 100, a vibration transmission unit 200, a vibration actuator 300, and a restraint unit 400. Here, the direction from Figure 10 right to left is referred to as the x-direction, the direction from Figure 10 the rear surface to the front surface of the paper surface is referred to as the y-direction, and from Figure 10The direction from the bottom to the top (the direction from the vibration actuator 300 to the display panel 100) is referred to as the z-direction. The positional relationships among the display speaker 10, the x-direction, the y-direction, and the z-direction are similarly applied to other drawings. Meanwhile, these directions are shown for ease of explanation, and the present embodiment is not limited to these directions. For example, the posture of the display panel 10 is not limited to these directions. The display panel 100 is an example of a panel. The display speaker is an example of a panel-type speaker. The vibration actuator 300 is an example of an actuator. The actuator attachment structure in the present embodiment includes a vibration transmission unit 200, a vibration actuator 300, and a restraint unit 400.

[0064] The display panel 100 is a display element included in a liquid crystal monitor, an organic EL (electroluminescence) display, etc., and outputs video when an input video signal is received. The display panel 100 has a substantially flat plate shape, and the vibration actuator 300 is connected to the surface (rear surface) of the display panel 100 opposite to the video display surface (front surface) via the vibration transmission unit 200. The display panel 100 is an example of a target panel vibrated by the vibration actuator 300.

[0065] The vibration transmission unit 200 has one end connected to the display panel 100 and the other end connected to the vibration actuator 300, and the vibration transmission unit 200 transmits the vibration of the vibration actuator 300 to the display panel 100. The vibration transmission unit 200 has a screw receiving portion 210 (a portion to be fastened) and a vibration transmission body 220 provided around the screw receiving portion 210. The screw receiving portion 210 stands on the rear surface 101 of the display panel 100, and a female thread portion 215 to which the restraint unit 400 is attached is provided on the free end side of the screw receiving portion 210.

[0066] The vibration transmission body 220 has an outer shape of a substantially rectangular parallelepiped, and a display side contact surface 221 in contact with the rear surface of the display panel 100 and an actuator side contact surface 222 in contact with the vibration actuator 300 are provided in parallel. The vibration transmission body 220 has a hole 223 through which the screw receiving portion 210 passes. The vibration transmission body 220 may have other outer shapes as long as the vibration transmission body 220 has the display side contact surface 221 and the actuator side contact surface 222. For example, the vibration transmission body 220 may have a columnar shape such as a quadrangular prism or a cylinder. The vibration transmission unit 200 is made of, for example, resin, metal, etc.

[0067] In the present embodiment, a screw receiving portion 210, which is part of the vibration transmission unit 200, is integrally formed with the display panel 100. However, the vibration transmission unit 200 is not limited thereto, and the vibration transmission unit 200 may be separately formed from the display panel 100 and fixed to the display panel 100 with an adhesive or double-sided tape.

[0068] The vibration actuator 300 includes a vibration plate 310, a piezoelectric element 320, and a piezoelectric element 330. The piezoelectric element 320 is attached to a surface (referred to as a first surface) of the vibration plate 310 facing the display panel, and the piezoelectric element 330 is attached to a surface (referred to as a second surface) of the vibration plate 310 opposite to the first surface. The vibration plate 310 of the vibration actuator 300 is coupled to the display panel 100 via the vibration transmission unit 200.

[0069] The vibration plate 310 of the vibration actuator 300 is a rectangular plate-shaped member in a plan view, and the vibration plate 310 has a front surface (first surface) disposed on a side facing the display panel and a rear surface (second surface) opposite to the front surface. The shape of the vibration plate 310 may be circular or elliptical. In addition, the shape of the vibration plate 310 may have other shapes as long as it is symmetric in the lateral direction and symmetric in the longitudinal direction. The front surface is substantially parallel to the rear surface. In addition, the vibration plate 310 is disposed such that the front surface of the vibration plate 310 is substantially parallel to the rear surface of the display panel 100.

[0070] The piezoelectric elements 320 and 330 are piezoelectric elements configured such that when a voltage is applied thereto, their shapes deform in response to the voltage. For example, the piezoelectric elements 320 and 330 are piezoelectric elements made of a plate-shaped material (such as ceramics) that exhibits a piezoelectric effect. The piezoelectric elements 320 and 330 have electrodes attached thereto for applying a voltage. The piezoelectric element 320 is attached to the first surface of the vibration plate 310. The piezoelectric element 330 is attached to the second surface of the vibration plate 310. The piezoelectric element 320 has an opening formed to expose a central portion of the vibration plate 310 as observed from the first surface side. The piezoelectric element 320 has an opening in the central portion of the piezoelectric element. The vibration plate 310 has a portion (exposed portion) exposed at the central portion of the first surface of the vibration plate 310 through the opening of the piezoelectric element 320. The actuator-side contact surface of the vibration transmission unit 200 is connected to the opening. At this time, the piezoelectric element 320 and the vibration transmission unit 200 do not contact each other. On the other hand, one of the piezoelectric elements 320 and 330 may be omitted. In the present embodiment, the first surface and the second surface are in the x-y plane.

[0071] Figure 11It is a view of the vibration actuator 300 as observed from the first surface side. Piezoelectric elements 320 and 330 having openings are attached to the first surface and the second surface of the vibration plate 310 of the vibration actuator 300. Further, the central portion of the vibration plate 310 (the portion including the center of the first surface and the center of the second surface, the central portion in the plan view) is exposed through the openings of the piezoelectric elements 320 and 330. Here, if the shape of the vibration plate 310 is rectangular, the center of the first surface (or the second surface) of the vibration plate 310 is the intersection point of the two diagonals of the rectangle. Further, if the shape of the vibration plate 310 is circular or elliptical, the center of the first surface (or the second surface) of the vibration plate 310 is the center of the circle or the ellipse. Even if the vibration plate 310 has any other shape, the center of the first surface (or the second surface) of the vibration plate 310 can be defined by, for example, its center of gravity or the like.

[0072] The size of the opening of the piezoelectric element 320 (the size of the exposed portion of the vibration plate 310) is larger than the size of the actuator-side contact surface 222 of the vibration transmission unit 200 that contacts the vibration plate 310 ( Figure 11 the portion surrounded by the dashed line in). Therefore, the piezoelectric element 320 and the vibration transmission unit 200 do not contact each other. Here, although the shape of the opening of the piezoelectric element 320 is rectangular (or square), the shape of the opening of the piezoelectric element 320 can be circular or the like according to the shape of the vibration transmission unit 200. In order to increase the area of the piezoelectric element 320, it is preferable to make the size of the opening of the piezoelectric element 320 as small as possible.

[0073] The size of the opening of the piezoelectric element 330 (the size of the exposed portion of the vibration plate 310) is larger than the size of the region where the constraint unit 400 is arranged ( Figure 12 the portion surrounded by the dashed line in). Therefore, the piezoelectric element 330 and the constraint unit 400 do not contact each other. Here, although the shape of the opening of the piezoelectric element 330 is rectangular (or square), the shape of the opening of the piezoelectric element 330 can be circular or the like according to the shape of the constraint unit 400. In order to increase the area of the piezoelectric element 330, it is preferable to make the size of the opening of the piezoelectric element 330 as small as possible.

[0074] By increasing the areas of the piezoelectric elements 320 and 330, the output (maximum output) of the display speaker 10 can be made larger. Further, when observing the vibration actuator 300 from the first surface side and the second surface side, the outer ends of the piezoelectric elements 320 and 330 are preferably positioned within the ends of the vibration plate 310.

[0075] Further, a through hole 311 is provided near the center of the vibration plate 310 to allow the constraint unit 400 to pass through the through hole 311.

[0076] The restraint unit 400 is a bolt (fastening member) having a male threaded portion 410 and a head portion 420. In Figure 10 and Figure 12 example, two restraint units 400 are used, and the male threaded portion 410 of the restraint unit 400 passes through the through hole 311 from the second surface side of the diaphragm 310. The male threaded portion 410 is screwed into the female threaded portion 215 of the vibration transmission unit 200 and tightened until the head portion 420 abuts against the second surface of the diaphragm 310. Thus, the vibration transmission unit 200, the vibration actuator 300, and the restraint unit 400 are fastened together. In other words, the vibration actuator 300 is restrained by the restraint unit 400.

[0077] In the present embodiment, on the surfaces (the first surface and the second surface) of the diaphragm 310 where the piezoelectric elements 320 and 330 are provided, the direction along the longitudinal direction is defined as a specific direction (x direction), and the restraint length (the length from one end of the restraint unit to the opposite end in the specific direction) L1 defined by the two restraint units 400 is set to a predetermined length. The predetermined length is adjusted such that the resonance frequency of the bending vibration propagating in the plane of the diaphragm 310 in the specific direction becomes a predetermined frequency. For example, the screw receiving portion 210 is provided at a position where the restraint length L1 defined by the restraint unit 400 becomes the predetermined length.

[0078] In this way, even if the vibration actuator 300 resonates with the display panel 100 or the like and the sound of a specific resonance frequency is enhanced, the resonance frequency can be set to an appropriate value such that the resonance frequency is balanced in the entire frequency band of the sound output from the display panel 100. In other words, appropriate frequency characteristics can be obtained instead of a sound with some frequencies being prominent. Therefore, without changing the sizes of the display panel 100 or the vibration actuator 300, the resonance frequency can be set only by the length L1 of the restrained portion, thereby obtaining appropriate frequency characteristics with a simple configuration. For example, by setting the resonance frequency to be higher, it is possible to reproduce a high-pitched sound while ensuring the sound pressure.

[0079] In addition, when adjusting the resonance frequency in the specific direction, for example, the restraint length L1 of the restraint unit 400 can be set such that the resonance frequency of the bending vibration propagating in the x direction (the first direction) of the diaphragm approaches the resonance frequency of the bending vibration propagating in the y direction (the second direction) orthogonal to the x direction.

[0080] Therefore, even better frequency characteristics can be obtained in the entire frequency band of the sound output from the display panel 100.

[0081] (Fifth modification)

[0082] Figure 14It is a view showing an actuator holding structure according to a fifth modification. This modification is different from the above-described second embodiment in the restraining direction of the restraining unit 400. At the same time, since other configurations are the same as those in the above-described second embodiment, the same elements are denoted by the same reference numerals, and their repeated descriptions will be omitted.

[0083] In the above-described second embodiment, the longitudinal direction of the diaphragm 310 is defined as a specific direction, and the resonance frequency in this direction is adjusted. However, in this modification, the width direction of the diaphragm 310 is defined as the specific direction, and the resonance frequency in this direction is adjusted. In other words, in this modification, two restraining units 400 are arranged in the y direction along the surfaces (the first surface and the second surface) of the diaphragm 310 where the piezoelectric elements 320 and 330 are provided. Therefore, although not shown in the figure, the screw receiving portions 210 fastened to these restraining units 400 are also arranged in the y direction. Further, the restraining length L2 of the restraining unit 400 is set to a predetermined length. The predetermined length is adjusted so that the resonance frequency when the diaphragm 310 bends and vibrates in the y direction becomes a predetermined frequency.

[0084] Therefore, the resonance frequency when the diaphragm 310 of the vibration actuator 300 bends and vibrates in the y direction can be set to an appropriate value.

[0085] (Sixth modification)

[0086] Figure 15 It is a view showing an actuator holding structure according to a sixth modification, and Figure 16 is a view of the vibration transmission unit 200A according to the sixth modification as viewed from the actuator side. This modification is different from the above-described second embodiment in that the actuator is restrained in a plurality of directions by the restraining unit 400. At the same time, since other configurations are the same as those in the above-described second embodiment, the same elements are denoted by the same reference numerals, and their repeated descriptions will be omitted.

[0087] In the above-described second embodiment, the resonance frequency in the longitudinal direction (the first direction) of the diaphragm 310 is adjusted. However, in this modification, in addition to this, the resonance frequency in the width direction (the second direction) of the diaphragm 310 is also adjusted. For this purpose, in this modification, as Figure 16 shown, the first screw receiving portion (the fastened portion) 211 of the vibration transmission unit 200A is provided at two positions in the x direction (the first direction), and the second screw receiving portion 212 is provided at two positions in the y direction (the second direction). Further, the restraining unit 400 is fastened to each of the screw receiving portions 210 (211, 212).

[0088] Here, similar to the above-described second embodiment and fifth modification, the constraint length (first length) L1 of the constraint unit 400 in the x direction and the constraint length (second length) L2 of the constraint unit 400 in the y direction are set such that the resonance frequency when the diaphragm 310 bends and vibrates in the x direction or the y direction has a predetermined value.

[0089] Therefore, the resonance frequency of the vibration actuator 300 in the x direction can be set to an appropriate value, and the resonance frequency in the y direction can be set to an appropriate value. For example, even if the diaphragm has a nearly square shape with sides having substantially the same length in the x direction and the y direction, or a nearly circular shape with a diameter having substantially the same length in the x direction and the y direction, by setting the constraint lengths L1 and L2 to different lengths, the resonance frequency in the x direction and the resonance frequency in the y direction can be set to different frequencies. As a result, the sound output from the display panel 100 does not concentrate on a specific frequency, and good frequency characteristics can be obtained over the entire frequency band.

[0090] In addition, the constraint unit (fastening member) 400 can be selectively fastened to the first screw receiving portion 211 arranged in the x direction or the second screw receiving portion 212 arranged in the y direction.

[0091] In this way, the constraint direction can be selected, and the resonance frequency in the x direction and the resonance frequency in the y direction can be selectively adjusted. Therefore, even if vibration actuators 300 having the same specifications are connected to display panels 100 having different aspect ratios, the frequency characteristics can be appropriately set. Accordingly, the vibration actuators 300 used in different products can be shared, and for example, it can facilitate the procurement of the vibration actuators 300.

[0092] (Seventh Modification)

[0093] Figure 17 is a view showing an actuator holding structure according to the seventh modification, and Figure 18 is a view of the vibration transmission unit 200B according to the seventh modification as viewed from the actuator side. This modification is different from the above-described second embodiment in that the constraint length L1 of the constraint unit 400 can be adjusted. At the same time, since other configurations are the same as those in the above-described second embodiment, the same elements are denoted by the same reference numerals, and their repeated description will be omitted.

[0094] In the above-described second embodiment, the constraint unit 400 is provided at two positions in a specific direction (x direction) of the diaphragm 310. However, in this modification, as Figure 18As shown, the vibration transmission unit 200B has screw receiving portions 210 (21-1 to 21-5) at five positions in a specific direction (x direction), and the constraint unit 400 can be selectively fastened to two of these positions. Meanwhile, the number of screw receiving portions 210 is not limited to this, and can be three or more.

[0095] According to this variant, the resonance frequency in the x direction can be arbitrarily adjusted by adjusting the constraint length of the constraint unit 400 fastened to the five screw receiving portions 21-1 to 21-5. For example, compared to the case where the constraint unit 400 is fastened to the screw receiving portion 21-2 and the screw receiving portion 21-4, when the constraint unit 400 is fastened to the screw receiving portion 21-1 and the screw receiving portion 21-5, the constraint length is longer and the resonance frequency can be set higher.

[0096] Therefore, the resonance frequency can be arbitrarily adjusted according to the usage environment of the display speaker 10 and the user's preference. In addition, even if vibration actuators 300 with the same specifications are connected to display panels 100 with different sizes and aspect ratios, the optimal constraint length can be selected according to the size of the display panel 100, etc., and the frequency characteristics can be appropriately set. Therefore, the vibration actuators 300 used in different products can be shared, and for example, it can facilitate the procurement of the vibration actuators 300.

[0097] Meanwhile, by applying this variant, as in the sixth variant above, when the screw receiving portions 210 are arranged in the x direction and the y direction, the screw receiving portions 210 can be provided at three or more positions in each of the x direction and the y direction to adjust the constraint lengths in the x direction and the y direction.

[0098] [Third Embodiment]

[0099] Figure 19 is a view showing an actuator holding structure according to the third embodiment, and Figure 20 is a view of the actuator holding structure according to the third embodiment as observed from the back surface side. The difference between this embodiment and the above-described second embodiment is that: the constraint unit 401 includes a fastening member 430 and a spacer 440, and the constraint length is set by the width (length) of the spacer 440. Meanwhile, since other configurations are the same as those in the second embodiment above, the same elements are denoted by the same reference numerals, and their repeated description will be omitted.

[0100] The spacer 440 is a flat member and has a through hole 441 that allows the fastening member 430 to pass through in the thickness direction (z direction in the figure). The spacer 440 is made of synthetic resin or metal and is configured to be able to constrain the vibration plate 310.

[0101] In the display panel 100 of the present embodiment, a screw receiving portion 210 stands upright at the center of the rear surface. Similarly, a through hole 311 allowing a fastening member 430 to pass therethrough is provided at a position at the center of the diaphragm 310.

[0102] In addition, as Figure 19 and Figure 20 shown, the male threaded portion 410 of the fastening member 430 passes through the through hole 441 of the spacer 440 and the through hole 311 of the diaphragm 310 from the rear surface side of the spacer 440. The male threaded portion 410 is screwed into the female threaded portion 215 of the screw receiving portion 210 and tightened until the head portion 420 touches the rear surface of the spacer 440. Accordingly, the vibration transmission unit 200, the vibration actuator 300, the spacer 440, and the fastening member 430 are fastened together. In other words, the vibration actuator 300 is constrained by the spacer 440 of the constraint unit 401.

[0103] In the present embodiment, the length L1 in the first direction (x direction) and the length L2 in the second direction (y direction) of the spacer 440 provided along the surface (second surface) of the diaphragm 310 on which the piezoelectric element 330 is provided are each set to have a predetermined length.

[0104] According to the present embodiment, by the lengths L1 and L2 of the spacer 440, the resonance frequency of the vibration actuator 300 in the x direction can be set to an appropriate value, and the resonance frequency in the y direction can be set to an appropriate value. For example, the resonance frequencies in the x direction and the y direction can be adjusted by preparing a plurality of types of spacers 440 having different lengths L1 and L2 and selecting the spacer 440 having a desired resonance frequency.

[0105] Therefore, even if vibration actuators 300 having the same specifications are connected to display panels 100 having different sizes and aspect ratios, the optimal constraint length can be selected according to the size of the display panel 100 or the like, and the frequency characteristics can be appropriately set. Accordingly, the vibration actuators 300 used in different products can be shared, and for example, it can facilitate the procurement of the vibration actuators 300.

[0106] (Eighth modification)

[0107] Figure 21 is a view showing an actuator holding structure according to the eighth modification, Figure 22It is a view seen from the rear surface side of the actuator holding structure according to the eighth variant. The difference between this variant and the above-described third embodiment is that a plurality of fastening members 430 are provided in the restraint unit 402. At the same time, since other configurations are the same as those in the above-described third embodiment, the same elements are denoted by the same reference numerals, and their repeated description will be omitted.

[0108] In this variant, similar to Figure 10 the example, two screw receiving portions 210 are erected near the center of the rear surface of the display panel 100, and the fastening members 430 are respectively fastened to the screw receiving portions 210. The male threaded portion 410 of the fastening member 430 passes through the through hole 441 and the through hole 311 of the diaphragm 310 from the rear surface side of the spacer 440. The male threaded portion 410 is screwed into the female threaded portion 215 of the screw receiving portion 210 and tightened until the head portion 420 touches the rear surface of the spacer 440.

[0109] Therefore, the vibration transmission unit 200, the vibration actuator 300, the spacer 440, and the fastening member 430 are fastened together. In other words, the vibration actuator 300 is restrained by the spacer 440 of the restraint unit 402.

[0110] According to this variant, similar to the above-described third embodiment, the resonance frequencies of the vibration actuator 300 in the x-direction and the y-direction can be set by the lengths L1 and L2 of the spacer 440, and appropriate frequency characteristics can be obtained. Therefore, for example, when it is desired to share the display speaker 10 and the vibration actuator 300 of the second embodiment and it is desired to set a resonance frequency other than the frequency determined by the restraint length of the restraint unit 400 as in the second embodiment, then the spacer 440 can be added, and the resonance frequency can be set according to the lengths L1 and L2 of the spacer 440 as in this variant.

[0111] Although the embodiments of the present invention have been described above, these embodiments are shown only by way of example. Therefore, the present invention is not limited thereto, and various different modifications can be made based on the knowledge of those skilled in the art without departing from the scope of the claims.

Claims

1. A panel-type speaker, the panel-type speaker including a panel and an actuator, and the panel-type speaker being configured to vibrate the panel through the actuator so as to output sound waves from the panel, the speaker comprising: a vibration transmission unit having one end connected to the panel and the other end connected to the actuator, and the vibration transmission unit being configured to transmit the vibration of the actuator to the panel; and a constraint unit configured to constrain the actuator to the vibration transmission unit, wherein the actuator includes: a diaphragm; and a piezoelectric element disposed on at least one surface of the diaphragm, wherein a length of a part of the constraint unit in a specific direction is set to a predetermined length such that a resonance frequency of a bending vibration propagating in the specific direction in a plane of the diaphragm becomes a predetermined frequency.

2. The panel-type speaker according to claim 1, wherein, the diaphragm is rectangular in a plan view, and the specific direction is a direction along a longitudinal direction of the diaphragm in the plan view.

3. The panel-type speaker according to claim 2, wherein, the length of the part of the constraint unit in the specific direction is set to a predetermined length such that the resonance frequency of the bending vibration propagating in the specific direction approaches a frequency of a bending vibration propagating in a direction orthogonal to the specific direction.

4. The panel-type speaker according to claim 3, wherein, the constraint unit includes a fastening member for fastening to the vibration transmission unit, wherein the diaphragm is constrained to the vibration transmission unit by the fastening members provided at at least two positions in the specific direction, and a length of a constrained portion is defined by a gap between the fastening members in the specific direction.

5. The panel-type speaker according to any one of claims 1 to 3, wherein, the constraint unit includes a fastening member and a flat spacer, the fastening member for fastening to the vibration transmission unit, wherein the spacer contacts a surface of the diaphragm opposite to a surface connected to the vibration transmission unit, and the fastening member is fastened to the vibration transmission unit via the spacer, wherein the length of the constrained portion in the specific direction is defined by the length of the spacer in the specific direction.

6. The panel-type speaker according to any one of claims 1 to 3, wherein, when the specific direction is defined as a first direction in a plan view and a direction orthogonal to the first direction is defined as a second direction, a length of the constrained portion defined by the constraint unit in the second direction is set to a second length such that a resonance frequency of a bending vibration propagating in the plane of the diaphragm and in the second direction becomes a predetermined frequency.

7. The panel-type speaker according to claim 6, wherein, The vibration transmission unit includes fastened members at at least two positions in the first direction and fastened members at at least two positions in the second direction, wherein the fastening members are fastened to the fastened members and can select a constraint direction by selectively fastening the fastening members to the fastened members in the first direction or the fastened members in the second direction.

8. The panel type speaker according to any one of claims 1 to 3, wherein, the vibration transmission unit includes fastened members at three or more positions in the specific direction, wherein the fastening members are fastened to the fastened members, and the length of the constrained portion is set by a gap between the fastening members fastened to two of the fastened members.

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