Audio output device

Abstract

In one embodiment, this audio output device is provided with a functional component, a peripheral member, a vibration generation unit, and a drive unit. The functional component has a predetermined function. The peripheral member is disposed around the functional component. The vibration generation unit includes one or more stretchable elements that are stuck to the peripheral member through a sticking surface facing the peripheral member and expand and contract in an in-plane direction of the sticking surface to vibrate the peripheral member. The drive unit expands and contracts the one or more stretchable elements on the basis of an audio signal.

Description

Audio output device

[0001] The present technology relates to an audio output device that can be applied to an image display device or the like.

[0002] Patent Document 1 describes a vibration mechanism that vibrates a component of an image display device such as a television set to output sound. This vibration mechanism has a contact member that contacts the component to be vibrated, and vibrates the contact member along a predetermined vibration axis V. The vibration mechanism is fixed inside the image display device so that the vibration axis V intersects with the surface of the component. This makes it possible to make a component such as a bezel that constitutes the image display device function as a speaker (see, for example, paragraphs

[0029] ,

[0031] ,

[0033] , and FIG. 2 of the specification of Patent Document 1).

[0003] International Publication No. 2021 / 117575

[0004] For example, various devices with audio output functions, such as the image display device described above, have been developed. For such devices, there is a demand for technology that improves sound quality and realizes excellent sound image expression.

[0005] In view of the above circumstances, an object of the present technology is to provide an audio output device that can improve the sound quality of the device and realize excellent sound image expression.

[0006] In order to achieve the above object, an audio output device according to one embodiment of the present technology includes a functional component, a peripheral component, a vibration generating unit, and a driving unit. The functional component has a predetermined function. The peripheral component is disposed around the functional component. The vibration generating unit has one or more expansion elements that are attached with an attachment surface facing the peripheral component and expand and contract in an in-plane direction of the attachment surface to vibrate the peripheral component. The driving unit expands and contracts the one or more expansion elements based on an audio signal.

[0007] In this audio output device, one or more expansion elements driven by an audio signal are attached to a peripheral component arranged around the functional component with their attachment surfaces facing the functional component. The one or more expansion elements vibrate the peripheral component by expanding and contracting in an in-plane direction of the attachment surface. By vibrating the peripheral component in an in-plane direction in this way, the sound quality of the device can be improved and excellent sound image expression can be achieved.

[0008] The functional component may be a display panel, in which case the audio output device may function as a display device that displays an image using the display panel.

[0009] The peripheral member may include a bezel that surrounds an outer edge of the display panel and a rear chassis that supports the display panel from the rear side of the display panel, and in this case, the elastic element may be attached to at least one of the bezel or the rear chassis.

[0010] The bezel may have an inner surface facing the outer edge of the display panel, and in this case, the elastic element may be attached to the inner surface of the bezel.

[0011] The inner surface may include a left inner surface provided on a left edge of the bezel and a right inner surface provided on a right edge of the bezel. In this case, the vibration generating unit may include an expansion element disposed on the left inner surface and an expansion element disposed on the right inner surface.

[0012] The inner surface may include an upper inner surface provided on an upper edge of the bezel and a lower inner surface provided on a lower edge of the bezel. In this case, the vibration generating unit may include an expansion element disposed on the upper inner surface and an expansion element disposed on the lower inner surface.

[0013] The rear chassis may have a plate-shaped rear portion disposed along the display panel, and in this case, the elastic element may be attached to the rear portion.

[0014] The rear chassis may have a plate-shaped rear portion disposed along the display panel and side portions surrounding the rear portion, in which case the elastic element may be attached to the side portions.

[0015] The rear chassis may have a plate-shaped rear portion disposed along the display panel and a protruding portion protruding from the rear portion, in which case the elastic element may be attached to the protruding portion.

[0016] The expansion element may be attached to a surface of the peripheral member that is parallel to or inclined with respect to the front-rear direction of the audio output device.

[0017] The expansion element may be attached to a surface of the peripheral member that is perpendicular to the front-rear direction of the audio output device.

[0018] The expansion element may be a piezoelectric element that forms the attachment surface and has an expansion portion that expands and contracts along an in-plane direction of the attachment surface.

[0019] The stretchable portion may be a plate-like member that is long in one direction or a plate-like member that has a square planar shape.

[0020] The functional component may be a display panel. In this case, the peripheral component may include a bezel surrounding an outer edge of the display panel and a rear chassis supporting the display panel from the rear side. The expandable portion may be a plate-like member that is long in one direction and is attached to at least one of the bezel or the rear chassis so that its longitudinal direction is aligned with the vertical or horizontal direction of the display panel.

[0021] The functional component may be a display panel. In this case, the peripheral component may include a bezel surrounding an outer edge of the display panel and a rear chassis supporting the display panel from the rear side. The expandable portion may be a plate-like member that is long in one direction and is attached to at least one of the bezel or the rear chassis so that its longitudinal direction is aligned with the front-to-rear direction of the display panel.

[0022] The vibration generating section may include a plurality of piezoelectric elements having expandable sections with different shapes.

[0023] The piezoelectric element may have a connector substrate to which a signal from the drive section is input, and a flexible substrate that connects the expandable section and the connector substrate.

[0024] The vibration generating section may have one or more element groups in which a plurality of expansion elements are connected in parallel or in series.

[0025] 7 is a schematic diagram showing a configuration example of an image display device according to an embodiment of the present technology; FIG. 8 is a schematic perspective view showing a configuration example of a display unit of the image display device; FIG. 9 is a schematic diagram showing a configuration example of a piezoelectric element; FIG. 10 is a schematic diagram for explaining the expansion and contraction operation of the piezoelectric element; FIG. 11 is a schematic cross-sectional view showing a configuration example of an image display device equipped with a piezoelectric element; FIG. 12 is a schematic diagram of the image display device shown in FIG. 5 viewed from the rear side; FIG. 13 is a schematic cross-sectional view showing another configuration example of an image display device equipped with a piezoelectric element; FIG. 14 is a schematic cross-sectional view showing another configuration example of an image display device equipped with a piezoelectric element; FIG. 15 is a schematic cross-sectional view showing another configuration example of an image display device equipped with a piezoelectric element; FIG. 16 is a schematic cross-sectional view showing another configuration example of an image display device equipped with a piezoelectric element;

[0026] Hereinafter, embodiments of the present technology will be described with reference to the drawings.

[0027] [Configuration of image display device] Fig. 1 is a schematic diagram showing a configuration example of an image display device according to an embodiment of the present technology. The image display device 100 is a device that reproduces images and sounds based on, for example, image signals and sound signals. The image display device 100 is an example of an audio output device according to this embodiment.

[0028] The image display device 100 is configured as, for example, a television device that receives television broadcast signals. Note that the image display device 100 may also be configured as a monitor device that reproduces image signals and audio signals output from a PC or the like. The image display device 100 has a display unit 10, a vibration generating unit 30, and a drive unit 50.

[0029] The display unit 10 is the main body of the image display device 100, and displays an image on a display surface 11 based on an image signal. The display unit 10 has, for example, a thin rectangular parallelepiped shape overall, and is used by placing it on a desk or a pedestal while being held by a holder such as legs. The display unit 10 may also be used by hanging it on a wall.

[0030] In this embodiment, the display unit 10 will be described as an example in which a liquid crystal panel (display panel 12 described later) is mounted as a display element. Note that the present technology can also be applied to cases in which a display element other than a liquid crystal panel is used, and for example, a self-luminous display panel (such as an organic EL panel or an LED display in which LEDs (Light Emitting Diodes) are arranged in a grid pattern) may be used.

[0031] Hereinafter, the side of the image display device 100 on which the display surface 11 is arranged will be referred to as the front side of the image display device 100, and the opposite side will be referred to as the rear side. Furthermore, the X direction, Y direction, and Z direction, which are mutually orthogonal, are defined based on the display surface 11. The X direction is the left-right direction (the horizontal direction of the display surface 11) when the display surface 11 is viewed from the front side. The Y direction is the up-down direction of the display surface 11 (the vertical direction of the display surface 11). The Z direction is the direction orthogonal to the display surface 11, and is the front-rear direction of the image display device 100. Note that the orientation or direction in which the image display device 100 is used is not limited.

[0032] 2 is a schematic perspective view showing an example of the configuration of the display unit of the image display device, in which the components constituting the display unit 10 are shown in an exploded state.

[0033] The display unit 10 has a display panel 12, an optical film 13, a diffuser 14, and a backlight 15. In the display unit 10, the display panel 12, the optical film 13, the diffuser 14, and the backlight 15 are arranged in layers in this order from the front side. The display unit 10 also has a bezel 16, a rear chassis 17, and a rear cover 18.

[0034] The backlight 15 is a plate-shaped light source unit that emits light toward the display panel 12. Here, the light emitted from the backlight 15 toward the display panel 12 is referred to as irradiated light. As the backlight 15, for example, a light source unit in which LEDs are arranged in a plane, or a light source unit that emits light from the entire light guide plate using a fluorescent tube or the like is used.

[0035] The diffusion plate 14 is disposed in front of the backlight 15 and diffuses the illumination light emitted from the backlight 15. By passing the illumination light through the diffusion plate 14, the brightness distribution of the illumination light is made uniform.

[0036] The optical film 13 is disposed in front of the diffuser plate 14 and adjusts the optical characteristics of the irradiated light that has passed through the diffuser plate 14. As the optical film 13, a prism sheet that aligns the traveling direction of the irradiated light or a deflection sheet that aligns the polarization of the irradiated light is used.

[0037] The display panel 12 is a display element that displays an image based on an image signal. The front main surface of the display panel 12 serves as the display surface 11 on which the image is displayed. In this embodiment, a liquid crystal panel is used as the display panel 12. The display panel 12 displays an image by modulating the light emitted from the backlight 15 for each pixel in accordance with the image signal. In this manner, the image display device 100, which is an audio output device according to this embodiment, functions as a display device that displays an image using the display panel 12. Note that a self-luminous display panel such as an organic EL panel or an LED display may also be used as the display panel 12. In this case, there is no need to provide a mechanism for generating the emitted light (the backlight 15, the diffuser 14, and the optical film 13).

[0038] The bezel 16 is a member that surrounds the outer edge of the display panel 12 and forms the outer frame of the display panel 12 (display surface 11). The bezel 16 is configured as a rectangular frame as a whole, and houses the display panel 12, the optical film 13, the diffuser plate 14, and the backlight 15, and functions as a housing for the display unit 10.

[0039] The bezel 16 is made of, for example, a metal material or a resin material such as plastic, but may also be made of a combination of these materials. The bezel 16 may also be formed by combining longitudinal members that form the right, left, upper, and lower sides, or may be formed as a member in which the longitudinal members that form the sides are integrally molded.

[0040] 2 , the bezel 16 has an inner surface 20 and a support portion 21. The inner surface 20 is a surface facing the outer edge of the display panel 12. In other words, the inner surface 20 is a surface facing inward where the display panel 12 and the like are housed, and is formed around the entire periphery inside the bezel 16. The inner surface 20 includes a left inner surface 20a provided on the left edge of the bezel 16, a right inner surface 20b provided on the right edge of the bezel 16, an upper inner surface 20c provided on the top edge of the bezel 16, and a lower inner surface 20d provided on the bottom edge of the bezel 16.

[0041] The support portion 21 is a portion that supports each component (such as the display panel 12, the optical film 13, the diffusion plate 14, and the backlight 15) surrounded by the bezel 16. The support portion 21 is provided with shapes for fitting each component, as well as screw holes and engagement portions for fixing each component.

[0042] In the example shown in Fig. 2, the support portions 21 are formed on the left inner surface 20a and the right inner surface 20b, respectively. Note that the support portions 21 may also be formed on the upper inner surface 20c or the lower inner surface 20d. The specific shape of the support portions 21 will be described later with reference to Fig. 5 etc.

[0043] The rear chassis 17 is a plate-shaped structural member provided on the rear side of the display unit 10, and supports the components constituting the display unit 10 from the rear side. Specifically, the rear chassis 17 supports the bezel 16 and the components so that the display panel 12 and other components housed in the bezel 16 do not sag. In this way, the rear chassis 17 can be said to be a member that supports the display panel 12 from the rear side of the display panel 12.

[0044] The rear chassis 17 is made of a highly rigid material such as a metal plate. For example, the rear chassis is formed by processing a metal plate such as aluminum into a predetermined shape. The rear chassis 17 may also be made of a combination of resin materials and the like.

[0045] As shown in Fig. 2, the rear chassis 17 has a rear portion 25 and side portions 26. The rear portion 25 is a plate-like structural portion arranged along the display panel 12. In Fig. 2, the rear portion 25 is arranged immediately behind the backlight 15. For example, components such as the display panel 12 housed in the bezel 16 are covered from the rear side by the rear portion 25 when the rear chassis 17 is attached. The rear portion 25 is a flat member overall, but may be provided with structures such as protrusions and grooves as appropriate.

[0046] The side surface portions 26 are structural parts that surround the rear surface portion 25 and form the sides of the rear surface chassis 17. In this example, the side surface portions 26 are wall-like structures that protrude forward along the outer edge of the rear surface portion 25. In FIG. 2, the side surface portions 26 are formed so as to surround the entire periphery of the rear surface portion 25, but the side surface portions 26 may be formed only on part of the outer edge of the rear surface portion 25. By providing the side surface portions 26, the rear surface portion 25 is less likely to bend, and the rigidity of the rear surface chassis 17 is increased.

[0047] The rear cover 18 is a cover that forms the rear surface of the display unit 10. The rear cover 18 is disposed behind the rear chassis 17 and is connected to the bezel 16 to function as a housing for the display unit 10. Note that the rear cover 18 does not need to cover the entire rear chassis 17, and may cover only a portion of the rear chassis 17, for example.

[0048] In addition, the display unit 10 is provided with a control device that processes image signals and controls the display panel 12, a receiving module that receives television broadcasts, a storage unit that stores image signals, etc. In addition to the vibration generating unit 30 described below, an audio reproducing element such as a speaker is also provided.

[0049] In this embodiment, the display panel 12 is an example of a functional component having a predetermined function. Here, the predetermined function is, for example, a function performed by a device to which the present technology is applied. Therefore, a component that realizes the function performed by the device is a functional component having the predetermined function. In other words, a functional component is a component that is essential for performing the predetermined function.

[0050] For example, the image display device 100 exemplified in this embodiment is a device that exhibits an image display function as a predetermined function. In this case, the display panel 12 that modulates light for each pixel is a functional component having the image display function. In this embodiment, the bezel 16 and rear chassis 17 are examples of peripheral components 5 arranged around the functional component (display panel 12). The present technology vibrates the peripheral components 5 around such functional components using piezoelectric elements 31 of a vibration generating unit 30 described below, thereby outputting sound from around the functional component.

[0051] Returning to Fig. 1 , the vibration generating unit 30 has a plurality of piezoelectric elements 31. In this embodiment, mainly flat-plate type piezoelectric elements 31 are used. In the example shown in Fig. 1 , the vibration generating unit 30 is made up of a piezoelectric element 31a arranged on the left side of the image display device 100 and a piezoelectric element 31b arranged on the right side. Note that the number of piezoelectric elements 31 that make up the vibration generating unit 30 is not limited, and for example, only one piezoelectric element 31 may be provided, or two or more piezoelectric elements 31 may be provided.

[0052] The piezoelectric element 31 has an attachment surface 32, is attached to the peripheral member 5 with the attachment surface 32 facing it, and expands and contracts in the in-plane direction of the attachment surface 32, vibrating the peripheral member 5. Therefore, the direction in which the peripheral member 5 vibrates is the in-plane direction of the surface of the peripheral member 5 to which the attachment surface 32 is attached. As a result, the peripheral member 5 to which the piezoelectric element 31 is attached functions as a speaker that outputs sound. In this embodiment, the piezoelectric element 31 is an example of an expansion and contraction element. Furthermore, the peripheral member 5 to which the piezoelectric element 31 is attached is a vibration target to which the piezoelectric element 31 applies vibration.

[0053] 1 , the piezoelectric element 31 is attached to the bezel 16, which is a peripheral member 5 of the display panel 12. For example, the piezoelectric element 31a is attached to the left inner surface 20a of the bezel 16 with its attachment surface 32 facing, and the piezoelectric element 31b is attached to the right inner surface 20b of the bezel 16 with its attachment surface 32 facing. Note that the position where the piezoelectric element 31 is attached and the type of peripheral member 5 are not limited. In this embodiment, a configuration in which the piezoelectric element 31 is attached to the rear chassis 17 in addition to the bezel 16 will also be described.

[0054] The drive unit 50 is configured by a circuit provided inside the image display device 100 (display unit 10), and expands and contracts each piezoelectric element 31 of the vibration generating unit 30 based on an audio signal. The drive unit 50 includes, for example, a signal processing unit that processes the audio signal, and an amplifier circuit that generates a drive signal for driving the piezoelectric element 31 based on the audio signal. Other than this, the specific configuration of the drive unit 50 is not limited, and for example, a filter circuit that suppresses noise in the audio signal and the drive signal, a distribution circuit that distributes each drive signal, etc. may be provided as appropriate.

[0055] [Configuration of Piezoelectric Element] Fig. 3 is a schematic diagram showing an example of the configuration of a piezoelectric element. Fig. 3A is a plan view of piezoelectric element 31 viewed from a direction perpendicular to attachment surface 32, and Fig. 3B is a side view of piezoelectric element 31 viewed from a direction parallel to attachment surface 32. As shown in Fig. 3, piezoelectric element 31 has an expandable portion 33, a connector substrate 34, and a flexible substrate 35.

[0056] The expandable portion 33 is the main body of the piezoelectric element 31 made of a piezoelectric material, forms the attachment surface 32, and expands and contracts along the in-plane direction of the attachment surface 32. Therefore, the expandable portion 33 can also be referred to as the piezoelectric element 31. When the piezoelectric element 31 is attached to the peripheral member 5, the expandable portion 33 is attached to the peripheral member 5.

[0057] As shown in FIG. 3 , the stretchable section 33 is configured as a flat plate-shaped member and has a first surface 36a and a second surface 36b. The first surface 36a is the surface to which the flexible substrate 35 (described later) is connected. The second surface 36b is the surface behind the first surface 36a. In this embodiment, the second surface 36b is used as the attachment surface 32. This makes it possible to attach the entire surface of the stretchable section 33 to the peripheral member 5 without being obstructed by the flexible substrate 35, for example. Note that the first surface 36b can also be used as the attachment surface 32.

[0058] The connector board 34 is a board to which signals from the drive unit 50 are input, and is configured as, for example, a rigid board. A predetermined connector 37 is provided on the connector board 34. The connector 37 is connected to input wiring 38 that transmits drive signals for driving the piezoelectric elements 31. The type of connector 37 is not limited.

[0059] The flexible substrate 35 is a bendable substrate (so-called FPC: Flexible Printed Circuits) and connects the expansion / contraction section 33 and the connector substrate 34. By providing the flexible substrate 35, it becomes possible to change the orientation of the connector substrate 34 even when the expansion / contraction section 33 is attached to the peripheral member 5, for example. This makes it easy to connect and route the input wiring 38.

[0060] In this way, the piezoelectric element 31 is structured so that an audio signal (drive signal) can be input from the outside to the expansion / contraction section 33 made of a piezoelectric material. The piezoelectric element 31 (more specifically, the attachment surface 32 of the expansion / contraction section 33) is attached to the surface of the peripheral member 5 with double-sided tape or adhesive. This allows the expansion / contraction vibration of the expansion / contraction section 33 caused by the audio signal to be transmitted to the peripheral member 5, causing sound to be generated from the peripheral member 5.

[0061] For example, using double-sided tape makes it easier to attach and detach the piezoelectric element 31, improving maintainability. The thinner the double-sided tape, the easier it is to transmit stretching vibrations, which is expected to have the effect of improving sound quality. On the other hand, if the double-sided tape is made thinner, it is possible that the reliability of the adhesion will decrease and that heat generated by the piezoelectric element 31 will be more easily transmitted to the peripheral component 5. For these reasons, the type and thickness of the double-sided tape are appropriately selected taking into consideration, for example, sound quality, adhesion reliability, heat transmission, etc. Note that the type and thickness of the double-sided tape are not limited and may be selected appropriately as needed. The expansion and contraction operation of the piezoelectric element will be described below.

[0062] Fig. 4 is a schematic diagram for explaining the expansion and contraction operation of the piezoelectric element. In this embodiment, an element called a d31 type piezoelectric actuator is used as the expansion and contraction section 33. Fig. 4 schematically illustrates an example of the cross-sectional configuration of the d31 type piezoelectric element 31 (expansion and contraction section 33).

[0063] The d31 type piezoelectric element 31 has a structure in which positive electrode layers 39P and negative electrode layers 39N are alternately stacked with a piezoelectric material 40 sandwiched between them. The stacking direction corresponds to the thickness direction of the flat expansion / contraction section 33. PZT (lead zirconate titanate) ceramics is typically used as the piezoelectric material 40.

[0064] As shown in Figure 4, when an external voltage is applied from a power source 41 to a d31 type piezoelectric element 31, an electric field (dotted arrow in the figure) is generated perpendicular to each layer of the piezoelectric material 40 (PZT ceramics). In this case, the piezoelectric element 31 (expandable portion 33) expands and contracts in an in-plane direction perpendicular to the thickness direction, i.e., in a horizontal direction parallel to each layer surface. In this way, the d31 type piezoelectric element 31 is an element that expands and contracts in a plane perpendicular to the direction of the electric field.

[0065] As a result, the piezoelectric element 31 shown in Fig. 4 expands and contracts not only in the horizontal direction in the figure, but also in the depth direction. Note that Fig. 4 illustrates two directions along the side of the plate-shaped piezoelectric element 31 as an example of the expansion and contraction direction, but in reality, expansion and contraction occurs isotropically. For example, if the piezoelectric element 31 has a circular planar shape, it will expand and contract in the radial direction with its center as the reference. Note that expansion and contraction also occurs in the thickness direction, although the amount of displacement is relatively small.

[0066] Furthermore, the longer the area (planar shape) to which voltage is applied, the greater the total amount of piezoelectric material that expands and contracts, and therefore the greater the amount of expansion and contraction of the d31 type piezoelectric element 31. The amount of expansion and contraction is a parameter related to, for example, sound pressure, and basically, the greater the amount of expansion and contraction, the greater the sound pressure of the sound generated from the component.

[0067] For example, in the example shown in Figure 3, the piezoelectric element 31 (expandable portion 33) is configured as a plate-like member that is long in one direction. In this case, the piezoelectric element 31 expands and contracts more in the longitudinal direction in its planar shape than in the lateral direction. Furthermore, the longer the longitudinal direction, the greater the expansion and contraction amount. In this way, by making the piezoelectric element 31 a plate-like member that is long in one direction, it is possible to increase the expansion and contraction amount while limiting the width in the lateral direction, thereby increasing the sound pressure.

[0068] The planar shape, area, thickness, number of layers, etc. of the piezoelectric element 31 are not limited. For example, the piezoelectric element 31 (expandable portion 33) may be configured as a plate-like member having a square planar shape. Using a square piezoelectric element 31 allows the amount of expansion and contraction to be the same in two mutually perpendicular directions. This makes it possible to configure a sound source that emits sound evenly in two mutually perpendicular directions. For example, as shown in FIG. 10 (described later), by attaching a square piezoelectric element 31 to a surface (the rear portion 25 of the rear chassis 17) arranged along the XY plane, it is possible to spread sound evenly in the X and Y directions. Furthermore, the planar shape of the piezoelectric element 31 is not limited to a rectangle and may be a circle, for example. The area (size) of the piezoelectric element 31 may be appropriately set depending on the area of ​​the installation portion, for example, so as to obtain desired sound pressure characteristics. The thickness and number of layers of the piezoelectric element 31 may be arbitrarily set depending on the space of the peripheral member 5, etc.

[0069] Furthermore, the piezoelectric material 40 is not limited to ceramic materials such as PZT, but may be a film-shaped material such as PVDF (polyvinylidene fluoride).The structure of the expansion / contraction section 33 does not necessarily have to be a laminated structure, and a piezoelectric element with a single layer structure may also be used.

[0070] Furthermore, although the d31 type piezoelectric element 31 has been described above, a d33 type piezoelectric actuator in which the direction of the electric field coincides with the expansion / contraction direction may also be used. The d33 type piezoelectric element 31 is, for example, a columnar element extending in the expansion / contraction direction, and in this case, the side surface along the expansion / contraction direction is attached to the peripheral member 5 as the attachment surface 32. Even in this case, it is possible to vibrate the peripheral member 5 along the in-plane direction of the attachment surface 32.

[0071] Below, we will explain typical examples of the arrangement of the piezoelectric element 31. Of course, the peripheral member 5 to which the piezoelectric element 31 is attached and the attachment position are not limited to the examples of the arrangement described below, and can be set arbitrarily.

[0072] [Configuration example of image display device] Below, a description will be given of configurations in which the member to which the piezoelectric element is attached is different. Fig. 5 is a schematic cross-sectional view showing a configuration example of an image display device equipped with a piezoelectric element. Fig. 6 is a schematic view of the image display device shown in Fig. 5 as seen from the rear side. Fig. 7 is a schematic cross-sectional view showing another configuration example of an image display device equipped with a piezoelectric element. Fig. 8 is a schematic view of the image display device shown in Fig. 7 as seen from the rear side. Fig. 9 is a graph showing an example of sound pressure frequency characteristics of audio output using a piezoelectric element.

[0073] First, the image display device 100a shown in Figures 5 and 6 will be described. Figure 5 shows a schematic diagram of the right-hand side structure as viewed from the front in a cross section of the display unit 10 of the image display device 100a taken along the XZ plane at the position where the piezoelectric element 31 is provided. Figure 6 is a plan view of the display unit 10 of the image display device 100a as viewed from the rear. In Figure 6, the left and right positions are reversed compared to Figures 5 and 1.

[0074] 5, the bezel 16 has an inner surface 20 (here, the inner surface 20 is parallel to the YZ plane) that is perpendicular to the display surface 11. Three support portions 21a, 21b, and 21c are formed on the inner surface 20. Note that the cross-sectional structure shown in FIG. 5 is merely an example, and the structures of the bezel 16, rear chassis 17, etc. can be designed as desired to suit the device configuration, etc.

[0075] The support portions 21a to 21c are plate-like structural portions that protrude from the inner surface 20 in the X direction and are formed in order from the front side at intervals from one another. The support portion 21a is provided, for example, at a position that is lowered rearward from the front end of the inner surface 20 by the thickness of the display panel 12. The display panel 12 is connected to the support portion 21a from the front side. The optical film 13 is connected between the support portions 21a and 21b, and the diffuser plate 14 is connected between the support portions 21b and 21c. The backlight 15 and the rear chassis 17 are connected to the support portion 21c from the rear side.

[0076] As shown in FIG. 5 , in the image display device 100a, sound is generated by attaching a piezoelectric element 31 to the inside of the bezel 16. That is, the piezoelectric element 31 is attached to the inner surface 20 of the bezel 16. Therefore, in the image display device 100a, the bezel 16 is the target of vibration for the piezoelectric element 31. Here, the piezoelectric element 31 is provided on a portion of the inner surface 20 that is rearward of the support portion 21c. Note that in FIGS. 5 and 6 , only the expandable portion 33, which is the main body of the piezoelectric element 31, is shown, and the connector board 34 and the like are not shown. In the example shown in FIG. 5 , for example, the piezoelectric element 31 is exposed when the rear cover 18 is removed, which facilitates installation and maintenance of the piezoelectric element 31.

[0077] 6, the piezoelectric elements 31 are arranged symmetrically on the left and right sides of the image display device 100. That is, the vibration generating unit 30 includes a piezoelectric element 31a arranged on the left inner surface 20a and a piezoelectric element 31b arranged on the right inner surface 20b. By arranging the piezoelectric elements 31a and 31b on the left and right sides of the display panel 12 in this manner, stereo sound reproduction and the like becomes possible.

[0078] In the image display device 100a, the piezoelectric element 31 attached to the bezel 16 expands and contracts mainly in the Y and Z directions. This force is transmitted to the bezel 16, vibrating the air outside the image display device 100a and generating sound.

[0079] Fig. 9 shows the results of measuring the sound pressure of sound reproduced by the piezoelectric element 31 at different frequencies in the image display device 100a shown in Fig. 5 and Fig. 6. The horizontal axis of the graph represents the logarithmic frequency [Hz], and the vertical axis represents the sound pressure [dB].

[0080] 9 also shows the measurement results for a comparative example using a vibration mechanism that plays back sound by bringing a piezoelectric actuator that vibrates along a predetermined vibration axis into contact with the surface of the bezel 16. The playback method of this comparative example is similar to the vibration mechanism described in, for example, Patent Document 1. In this method, the tip of the actuator is pressed against and in contact with the bezel, but is not adhered to it. The vibration mechanism of the comparative example is designed to vibrate the bezel 16 from the inside, primarily along the thickness direction (X direction).

[0081] In Figure 9, the sound pressure frequency characteristics of the image display device 100a are shown by a black dotted line, and the sound pressure frequency characteristics of the vibration mechanism of the comparative example are shown by a gray solid line. In each measurement, drive signals of the same voltage level were input to the vibration elements (piezoelectric element 31 of the image display device 100a and the actuator that constitutes the vibration mechanism of the comparative example). The sound pressure level was also detected using a microphone at a predetermined measurement position set in front of the device.

[0082] 9, it can be seen that the image display device 100a has a higher output sound pressure level than the comparative example. In other words, when the same voltage as the comparative example is applied, the image display device 100a can generate a louder sound. In this respect, it can be said that the efficiency as a speaker is improved.

[0083] The reason for the improved sound pressure level in the image display device 100a is the difference in the method of vibrating the vibrating target (bezel). For example, in order to radiate sound to the front of the display surface 11 where the user is located, that is, to increase the sound pressure heard in the front, it is advantageous to have a larger amplitude in the Z direction. The vibration mechanism of the comparative example vibrates the bezel from the X direction, so vibration in the Z direction is unlikely to occur.

[0084] In contrast, in the image display device 100a according to this embodiment, the piezoelectric element 31 is attached to a surface (here, the YZ plane) of the peripheral member 5 (here, the bezel 16) that is parallel to the front-to-back direction (Z direction) of the image display device 100a. This allows the piezoelectric element 31, which expands and contracts the surface of the member to which it is attached in the in-plane direction, to vibrate the bezel 16 in the front-to-back direction. This makes it possible to improve the sound pressure on the front side. Furthermore, the front-to-back vibration of the bezel 16 caused by the piezoelectric element 31 makes it possible to deliver sound directly to the viewer watching the display panel 12.

[0085] Furthermore, the piezoelectric element 31 attached to the bezel 16 vibrates the bezel 16 over the entire attachment surface 32. This significantly improves the vibration transmission efficiency compared to locally vibrating the bezel 16, and is expected to increase sound pressure. Furthermore, using the piezoelectric element 31, which expands and contracts in the in-plane direction, makes it possible to widen the sound image. Here, the sound image refers to, for example, the location and spread of a sensual sound source perceived by a user. For example, if the bezel 16 is vibrated locally as with the vibration mechanism of the comparative example, the spread of the sound image is limited, and it is expected that the user will perceive it as a localized sound source. In contrast, the piezoelectric element 31 vibrates the bezel 16 over the entire attachment surface 32, thereby realizing a wider sound image. This improves the sense of unity between the image and sound displayed on the display panel 12. For example, when an organic light-emitting diode (OLED) panel is used, a method of achieving a sense of unity between the image and sound can be considered by vibrating the panel itself as the sound source. On the other hand, when a liquid crystal panel is used as the display panel 12, it is difficult to vibrate the liquid crystal panel itself if a vibration element or the like is placed on the back of the liquid crystal panel, as this would block the light emitted from the backlight 15. In contrast, by using this technology, even in a display device (such as a liquid crystal television device) that uses a liquid crystal panel, it is possible to achieve a wide sound image and a sense of unity between the picture and the sound, in addition to allowing sound to reach the viewer directly, just like in the case of using an organic EL panel.

[0086] Furthermore, in the image display device 100a, the expandable portion 33 of the piezoelectric element 31 is attached to the bezel 16 so that its longitudinal direction is aligned with the vertical direction (Y direction) of the display panel 12. In other words, the expandable portion 33 that is long in the vertical direction is attached to the inner surface 20 of the bezel 16 that extends in the vertical direction. Therefore, for example, the length in the Z direction of the expandable portion 33 shown in Fig. 5 corresponds to the length in the short side direction, and the length in the Y direction of the expandable portion 33 shown in Fig. 6 corresponds to the length in the longitudinal direction.

[0087] For example, display devices have become thinner in recent years, and the width of the bezel 16 in the front-to-back direction (depth in the Z direction) has become very small. This makes it difficult to widen the expandable portion 33 in the Z direction. On the other hand, if the expandable portion 33 is made longer in the Y direction, it is easy to incorporate it into the device. Furthermore, by lengthening the expandable portion 33, the amount of expansion and contraction in the Y direction increases, making it possible to improve sound pressure.

[0088] Furthermore, because the expandable section 33 is long in the Y direction, the size of the sound source is also vertically long. This makes it possible to expand the sound image perceived by the user in the vertical direction. This makes it possible to create an acoustic space that envelops the entire user, and to fully improve the sense of unity between the image and sound.

[0089] The orientation in which the piezoelectric element 31 is attached can be set arbitrarily. For example, the expansion / contraction portion 33 of the piezoelectric element 31 may be attached to the bezel 16 so that its longitudinal direction is aligned with the front-to-rear direction (Z direction) of the display panel 12. In this case, the amount of expansion / contraction in the Z direction increases, making it possible to efficiently increase the sound pressure at the front of the device, for example. This arrangement may be adopted, for example, when the depth of the bezel 16 is sufficiently secured.

[0090] Next, the image display device 100b shown in Figures 7 and 8 will be described. Figure 7 shows a schematic diagram of the right side structure as viewed from the front of a cross section of the display unit 10 of the image display device 100b taken along the XZ plane at a position where the piezoelectric element 31 is provided. Figure 8 is a plan view of the display unit 10 of the image display device 100b as viewed from the rear.

[0091] As shown in FIG. 7 , in the image display device 100b, sound is generated by attaching a piezoelectric element 31 to the side of the rear chassis 17. That is, the piezoelectric element 31 is attached to the side surface 26 of the rear chassis 17. Therefore, in the image display device 100b, the rear chassis 17 is the target of vibration for the piezoelectric element 31. Here, the piezoelectric element 31 (expandable portion 33) is provided on the outer side surface (the side surface on the left in the figure) of the side surface portion 26 that protrudes forward from the rear surface 25 of the rear chassis 17. In the example shown in FIG. 7 , as in the case of FIG. 5 , the piezoelectric element 31 is exposed when the rear cover 18 is removed, facilitating installation and maintenance of the piezoelectric element 31. Note that the piezoelectric element 31 may also be attached to the inner side surface (the side surface on the right in the figure) of the side surface portion 26.

[0092] 8, the piezoelectric elements 31 are arranged symmetrically on the left and right sides of the image display device 100b, similar to the case of the image display device 100a. That is, the vibration generating unit 30 includes a piezoelectric element 31a arranged on the left side surface portion 26 and a piezoelectric element 31b arranged on the right side surface portion 26. This enables stereo sound reproduction, etc.

[0093] Furthermore, in the image display device 100b, the piezoelectric element 31 is attached to a surface (here, the YZ plane) of the peripheral member 5 (here, the rear chassis 17) that is parallel to the front-to-rear direction (Z direction) of the image display device 100b. This makes it possible to increase the sound pressure, for example, in the front. Furthermore, in the image display device 100b, the expandable portion 33 of the piezoelectric element 31 is attached to the rear chassis 17 so that its longitudinal direction is aligned with the up-and-down direction (Y direction) of the display panel 12. This makes it possible to increase the sound pressure and widen the sound image. These points are the same as those of the image display device 100a described above.

[0094] The expansion / contraction portion 33 of the piezoelectric element 31 may be attached to the rear chassis 17 so that its longitudinal direction is aligned with the front-to-rear direction (Z direction) of the display panel 12. For example, such an arrangement may be adopted when the width (depth) of the side portion 26 in the Z direction is sufficiently secured. This increases the amount of expansion / contraction in the Z direction, making it possible to efficiently increase the sound pressure at the front of the device, for example.

[0095] Fig. 9 shows the results (black solid line graph) of measurements of the sound pressure of sound reproduced using the piezoelectric element 31 at different frequencies in the image display device 100b shown in Fig. 7 and Fig. 8. The results show that when the image display device 100b is used, the reproducible frequency band is expanded to the lower range compared to the results using the vibration mechanism and image display device 100a of the comparative example, and that it is now possible to reproduce lower frequencies.

[0096] In this example, while the lower limit of the reproducible frequency in other devices was 4000 Hz or higher, when the rear chassis 17 was vibrated as in the image display device 100b, the reproducible frequency was expanded to 3000 Hz or lower. As a result, when reproducing human voice, for example, the user can hear the voice more clearly. This makes it possible to realize, for example, a television device that reproduces voice clearly.

[0097] In this way, the image display device 100b has a wider frequency band than the image display device 100a, which uses the piezoelectric element 31 that expands and contracts in the in-plane direction, just like the image display device 100b. The reason for the wider reproducible frequency band in the image display device 100b is the difference in the type of vibration target.

[0098] For example, in a device that reproduces sound by vibrating a peripheral component 5, a relatively high sound pressure can be obtained in the high frequency band within the human audible range (e.g., 20 Hz to 20 kHz). On the other hand, sufficient sound pressure may not be obtained in the low frequency band below a few kHz. Therefore, in such a device, expanding the reproducible frequency band means shifting the frequency characteristics to the low frequency side. In terms of the characteristics of the vibrating object, this is the same as lowering the resonant frequency of the vibrating object.

[0099] For example, when considering vibrating a plate-shaped member, the conditions for widening the frequency band (lowering the resonant frequency) include: 1. Make the plate thinner 2. Use a material with a low Young's modulus 3. Make the plate longer 4. Use a material with a high density Considering these conditions, one way to lower the resonant frequency is to use a heavy material (condition 4) as the excitation target.

[0100] From the above, it is believed that the difference in frequency characteristics between the image display devices 100a and 100b is due to the difference in weight between the bezel 16 and the rear chassis 17. For example, the rear chassis 17, which is formed in a plate shape, uses a larger amount of constituent material and is a relatively heavy member compared to the bezel 16, which constitutes only the frame portion. For this reason, even though the piezoelectric element 31 is arranged along the YZ plane as in the case of the image display device 100a, it is believed that the frequency band was broadened because the vibration target was the heavier rear chassis 17.

[0101] Furthermore, when the piezoelectric element 31 is attached to the rear chassis 17, sound generated from the rear chassis 17 propagates into the image display device 100b (display unit 10). As a result, sound is heard from near the center of the display panel 12 (to the right of the bezel 16 in FIG. 7 ) compared to when the vibration mechanism of the comparative example or the image display device 100a is used. This phenomenon enhances the sense of unity between the image displayed on the display panel 12 and the sound, making it possible to realize a high-quality acoustic space.

[0102] [Another Configuration Example of an Image Display Device] Fig. 10 is a schematic cross-sectional view showing another configuration example of an image display device equipped with a piezoelectric element. As shown in Fig. 10, in an image display device 100c, a piezoelectric element 31 is attached to the rear portion 25 of the rear chassis 17. Here, the piezoelectric element 31 (expandable portion 33) is provided on the surface of the rear portion 25 facing the rear (the upper surface in the figure). This facilitates the installation and maintenance of the piezoelectric element 31. Note that the piezoelectric element 31 may also be attached to the surface of the rear portion 25 facing the front (the lower surface in the figure).

[0103] In this way, in the image display device 100c, the piezoelectric element 31 is attached to a surface (XY plane) of the peripheral member 5 (here, the rear chassis 17) that is perpendicular to the front-to-rear direction (Z direction) of the image display device 100c. This allows the rear part 25 to expand and contract in the X and Y directions, making it possible to widen the sound image obtained when listening from in front of the display panel 12.

[0104] Furthermore, by providing the piezoelectric element 31 on the rear surface portion 25, it is possible to arbitrarily set the position of the piezoelectric element 31 in the left-right direction (X direction). For example, by arranging the piezoelectric element 31 closer to the center of the display panel 12, it is possible to enhance the sense of unity between the image and the sound.

[0105] Fig. 11 is a schematic cross-sectional view showing another example of the configuration of an image display device equipped with a piezoelectric element. In the image display device 100d shown in Fig. 11, the shape of the rear portion 25 of the rear chassis 17 is different from the other image display devices 100a, 100b, and 100c described so far.

[0106] The rear chassis 17 of the image display device 100d has a protrusion 45 that protrudes from the rear portion 25. The protrusion 45 is a convex structural portion that protrudes rearward or forward from the plane (XY plane) in which the rear portion 25 extends. In the example shown in Fig. 11, the protrusion 45 is formed by bending a part of the rear portion 25 so that it protrudes rearward. Such a protrusion 45 is formed by embossing a metal plate or the like that constitutes the rear portion 25.

[0107] 11, the portion of the protrusion 45 that rises from the rear surface portion 25 is inclined relative to the front-to-rear direction (Z direction). Hereinafter, the portion that forms the tip of the protrusion 45 will be referred to as a tip portion 46, and the inclined portion will be referred to as an inclined portion 47. The protrusion 45 has a structure in which the inclined portions 47 are formed on both the left and right sides of the tip portion 46.

[0108] 11 , in the image display device 100d, the piezoelectric element 31 is attached to the protruding portion 45 of the rear chassis 17. More specifically, the piezoelectric element 31 is attached to the inclined portion 47 of the protruding portion 45. Here, the piezoelectric element 31 (expandable portion 33) is provided on the surface facing the rear side of the inclined portion 47 formed on the left side in the figure (the upper surface in the figure). Note that the piezoelectric element 31 may be provided on the inclined portion 47 formed on the left side in the figure, or on the surface facing the front side of the inclined portion 47 (the lower surface in the figure).

[0109] As described above, in the image display device 100d, the piezoelectric element 31 is attached to a surface of the peripheral member 5 that is inclined with respect to the front-to-rear direction (Z direction) of the image display device 100d. In FIG. 11 , a vector d representing the expansion / contraction direction (vibration direction) of the piezoelectric element 31 in the XZ plane is schematically illustrated by a thick arrow. The piezoelectric element 31 is an element that vibrates the attached member along the in-plane direction of the surface at the attachment position. In the image display device 100d, the surface to which the piezoelectric element 31 is attached is inclined with respect to the Z direction. Therefore, the vector d can be divided into a Z-direction vibration component dz and an X-direction vibration component dx. This Z-direction vibration component dz makes it possible to generate Z-direction vibrations in the rear chassis 17.

[0110] 11, the amount of vibration in the Z direction is increased compared to when the piezoelectric element 31 is provided on a surface (XY plane) of the rear chassis 17 perpendicular to the Z direction as shown in FIG. 10. As a result, the sound pressure increases when listening from the front of the display panel 12, improving the sound pressure level obtained for the input voltage. In this way, it is possible to improve the efficiency as a speaker.

[0111] Fig. 12 is a schematic cross-sectional view showing another example of the configuration of an image display device equipped with a piezoelectric element. In the image display device 100e shown in Fig. 12, the cross-sectional shape of the bezel 16 is different from that of the other image display devices 100a to 100d described so far. As shown in Fig. 12, a support portion 21d and a support portion 21e are formed on the inner surface 20 of the bezel 16.

[0112] The support portion 21d is a plate-like structural portion that protrudes in the X direction from the front end of the inner surface 20 to the rear by the thickness of the display panel 12. The display panel 12 is connected to the support portion 21d from the front side, and the optical film 13 is connected to the support portion 21d from the rear side.

[0113] Support portion 21e is formed rearward of support portion 21d. Support portion 21e protrudes from inner surface 20 in the X direction and has a cross-sectional structure that bends rearward midway. The diffuser plate 14 is connected from the front to the base portion of support portion 21e (the portion protruding in the X direction). The backlight 15 and the rear chassis 17 are connected to the tip portion of support portion 21e.

[0114] In the image display device 100e, the piezoelectric element 31 is attached to the inner surface 20 of the bezel 16. The arrangement of this piezoelectric element 31 is similar to that of the image display device 100a shown in FIG. 5, for example. The location where the piezoelectric element 31 is provided is not limited to this, and for example, the piezoelectric element 31 may be attached to the tip portion of the support portion 21e, or the piezoelectric element 31 may be attached to the side portion 26 or rear portion 25 of the rear chassis 17, etc. In this way, the location where the piezoelectric element 31 is provided can be appropriately selected according to the shapes of the bezel 16, rear chassis 17, etc. This makes it possible to easily achieve the desired sound quality and sound image.

[0115] [Relationship between Piezoelectric Element Size and Sound Pressure] Fig. 13 is a graph showing an example of the sound pressure frequency characteristics of audio output using piezoelectric elements of different sizes. Here, we will explain the measurement results of the sound pressure frequency characteristics when two types of piezoelectric elements 31 with different lengths are used. Fig. 13 shows the results of measuring the sound pressure at the front of the image display device 100d shown in Fig. 11 when audio is output using piezoelectric elements 31 with different lengths in the up-down direction (Y direction) of the expandable portion 33.

[0116] The black dotted line graph shows the measurement results when using a piezoelectric element (P1) with a long expansion / contraction section 33, and the gray solid line graph shows the measurement results when using a piezoelectric element (P2) with a short expansion / contraction section 33. As shown in Fig. 13, when piezoelectric element P1 was used, the sound pressure level was higher in almost all frequency bands compared to when piezoelectric element P2 was used.

[0117] As described above, in the piezoelectric element 31 that expands and contracts in the in-plane direction, the longer the expansion / contraction portion 33, the greater the expansion / contraction amount (vibration amplitude). This is thought to be why a high sound pressure level was obtained when using the piezoelectric element P1. The results shown in Figure 13 also indicate that the sound pressure detected at the front of the device changes when the length in the up-down direction (Y direction), which is perpendicular to the front-to-back direction (Z direction), is changed. Therefore, even when the piezoelectric element 31 is arranged along the X direction, for example, it is possible to increase the sound pressure by increasing the length in the X direction. Furthermore, if the expansion / contraction portion 33 can be configured to increase the vibration component in the Z direction, it is possible to more efficiently increase the sound pressure output forward.

[0118] Furthermore, when piezoelectric elements 31 of different lengths are used, it has been found that the longer the expansion / contraction portion 33, the wider the reproducible frequency band becomes toward the lower frequency side. For example, in FIG. 13 , when piezoelectric element P1 is used, the frequency band where a sound pressure of 30 dB or more can be obtained is wider toward the lower frequency side than when piezoelectric element P2 is used. Furthermore, for example, the sound pressure that piezoelectric element P2 can output at around 15 kHz can be output at around 8 kHz with piezoelectric element P1. Thus, it can be said that piezoelectric element P1 can generate sounds at lower frequencies more efficiently than piezoelectric element P2. Due to these differences in characteristics, it is possible to use piezoelectric element P1 as a woofer and piezoelectric element P2 as a treble speaker, for example.

[0119] 14 is a schematic diagram showing an example of the arrangement of piezoelectric elements in an image display device. Up to this point, the configuration in which one piezoelectric element 31 is arranged on each of the left and right sides of the display panel 12 has been mainly described. For example, it is also possible to arrange a plurality of piezoelectric elements 31 along one side of the bezel 16 or the rear chassis 17.

[0120] In the image display device 100f shown in FIG. 14, two piezoelectric elements 31 are attached symmetrically to each of the left inner surface 20a (the inner surface 20 on the right side in the figure) and the right inner surface 20b (the inner surface 20 on the left side in the figure) of the bezel 16. That is, in the image display device 100f, the vibration generating unit 30 is configured by four piezoelectric elements 31. In this way, by arranging multiple piezoelectric elements 31 on one side, the vibrating area increases, making it possible to increase the sound pressure output from each side. Note that three or more piezoelectric elements 31 may be arranged on one side.

[0121] Furthermore, in the image display device 100f, the vibration generating unit 30 includes a plurality of piezoelectric elements 31 with different shapes of the expansion / contraction portion 33. Specifically, of the two piezoelectric elements 31 provided on the left inner surface 20a (or the right inner surface 20b), the piezoelectric element 31 with the longer expansion / contraction portion 33 is disposed on the lower side, and the piezoelectric element 31 with the shorter expansion / contraction portion 33 is disposed on the upper side. In this case, for example, the lower piezoelectric element 31 can be used to configure a woofer, and the upper piezoelectric element 31 can be used to configure a treble speaker. In this way, multi-way audio output is possible using a plurality of speakers with different corresponding frequency ranges, making it possible to expand the reproducible frequency band.

[0122] 14, for example, two-way speakers can be configured on the left and right sides of the display panel 12. This makes it possible to achieve, for example, stereo audio output with a wider reproducible frequency band.

[0123] It is also possible to shift the resonant frequency to a lower frequency by changing the thickness of the bezel 16 at the position where the piezoelectric element 31 is attached. This utilizes condition 1 of the conditions for lowering the resonant frequency described with reference to FIG. 9. For example, even if the shape and size of the piezoelectric element 31 are the same, the thinner the thickness at the attachment position, the lower the resonant frequency. Utilizing this, a multi-way speaker may be configured on each of the right and left sides.

[0124] 15 is a schematic diagram showing another example of the arrangement of piezoelectric elements in an image display device. In the image display device 100g shown in FIG. 15, piezoelectric elements 31 are attached to both the bezel 16 and the rear chassis 17. In this way, piezoelectric elements 31 may be provided on different peripheral components 5.

[0125] In the image display device 100g, one piezoelectric element 31 is attached symmetrically to each of the left and right inner surfaces 20a and 20b of the bezel 16. In addition, one piezoelectric element 31 is attached symmetrically to each of the left and right side surfaces 26 of the rear chassis 17.

[0126] In this way, by changing the peripheral component 5, the speaker characteristics change as described with reference to Figures 5 to 9, etc. For example, it is considered that the piezoelectric element 31 provided on the rear chassis 17 has a wider frequency band toward the lower frequency side than the piezoelectric element 31 provided on the bezel 16. This makes it possible to configure a woofer using the piezoelectric element 31 provided on the rear chassis 17 and a treble speaker using the piezoelectric element 31 provided on the bezel 16, for example. Furthermore, because the bezel 16 and the rear chassis 17 have piezoelectric elements 31 on both the left and right sides, the image display device 100g can have two-way speakers on each of the right and left sides.

[0127] Fig. 16 is a schematic diagram showing another example of the arrangement of piezoelectric elements in an image display device. Up to this point, an example has been described in which the piezoelectric elements 31 are arranged along the left and right sides when viewed from the front of the device. In contrast, in the image display device 100h shown in Fig. 16, the piezoelectric elements 31 are arranged at the corners of the bezel 16 (here, the upper and lower ends of the left inner surface 20a and the right inner surface 20b). This makes it possible, for example, to output stereo sound and to expand the stereo sound image in the vertical direction.

[0128] Fig. 17 is a schematic diagram showing another example of the arrangement of piezoelectric elements in an image display device. The image display device 100i shown in Fig. 17 includes a piezoelectric element 31 arranged on the inner surface 20 (upper inner surface 20c) formed on the upper edge of the bezel 16, and a piezoelectric element 31 arranged on the inner surface 20 (lower inner surface 20d) formed on the lower edge of the bezel 16. In this way, the piezoelectric element 31 may be arranged along the upper edge or lower edge of the bezel 16.

[0129] 17, the piezoelectric element 31 is attached to the bezel 16 so that its longitudinal direction is aligned with the left-right direction of the display panel 12. This makes it possible to realize a sound image that is wide in the left-right direction.

[0130] 17, piezoelectric elements 31 are provided at the center of the top and bottom edges of the display panel 12. This makes it possible to configure a center speaker that outputs sound from the center of the display panel 12, thereby creating a powerful acoustic space in front of the image display device 100i. Furthermore, when multiple users are viewing the image display device 100i, it is possible for the positions of the users to be shifted to the left or right. Even in such cases, it is possible to localize the sound image in the center of the screen, making it possible to provide a realistic viewing experience even to users who are positioned away from the front.

[0131] The number and positions of the piezoelectric elements 31 arranged on the upper and lower edges of the bezel 16 in the image display device 100i are not limited. For example, the piezoelectric elements 31 may be arranged on the right and left sides of the upper inner surface 20c (or the lower inner surface 20d) respectively, so that stereo speakers are configured on each of the upper and lower edges. Also, a center speaker and a stereo speaker may be configured on each of the upper and lower edges.

[0132] 16 and 17 show examples of the arrangement of the bezel 16, but these arrangement examples may also be applied to the rear chassis 17. That is, the piezoelectric elements 31 may be arranged in the center of the upper or lower edge of the rear chassis 17, or in the corners of the rear chassis 17. The piezoelectric elements 31 may also be arranged in any position on the rear section 25 of the rear chassis 17. In this case, for example, it is possible to arrange the piezoelectric elements 31 in several vertical stages in the center of the rear section 25, or to arrange multiple piezoelectric elements 31 on the left and right sides of the rear section 25 in a stereo arrangement. In addition, it is possible to use any combination of the arrangements shown in FIGS. 14 to 17.

[0133] When multiple piezoelectric elements 31 are installed, in addition to a drive method in which the electrical systems of each piezoelectric element 31 are completely separated, a configuration in which the elements are connected in series or parallel is also possible. In this case, the vibration generating unit 30 forms one or more element groups in which multiple piezoelectric elements 31 are connected in parallel or series. For example, when multiple piezoelectric elements 31 are connected in parallel, the drive voltage applied to each piezoelectric element 31 is the same, making it possible to easily control the piezoelectric elements 31. Furthermore, by connecting multiple piezoelectric elements 31 in series, it is possible to appropriately adjust the voltage applied to the piezoelectric elements 31, making it possible to realize a configuration in which the output of each piezoelectric element 31 is adjusted.

[0134] In either case, one element group can be controlled by one electrical system. This makes it possible to reduce the number of drive amplifiers used and the load on the sound adjustment DSP (Digital Signal Processor). As a result, the configuration of the drive unit 50 that drives the vibration generating unit 30 consisting of multiple piezoelectric elements 31 can be simplified and the processing load can be reduced.

[0135] As described above, in the image display devices 100, 100a to 100i according to the present embodiment, one or more piezoelectric elements 31 driven by an audio signal are attached to a peripheral member 5 arranged around the display panel 12, with their attachment surfaces 32 facing the display panel. The one or more piezoelectric elements 31 vibrate the peripheral member 5 by expanding and contracting in the in-plane direction of the attachment surface 32. By vibrating the peripheral member 5 in the in-plane direction in this manner, the sound quality of the device can be improved and excellent sound image expression can be realized. This allows a user viewing the display panel 12 to perceive a high-quality, expansive sound image, thereby significantly improving the sense of unity between the image and the sound. Furthermore, by using this technology, even when a liquid crystal panel is used for the display panel 12, it is possible to realize an expansive sound image and a sense of unity between the image and the sound, similar to when the panel itself is vibrated in an organic EL panel.

[0136] Generally, display devices such as televisions often have speakers located below the device set. In this case, sound comes from below the screen, which can result in a lack of integration between the image and sound, and a diminished sense of realism. In recent years, there has also been growing demand for display devices with slimmer profiles and narrower bezels, resulting in a high-quality audio experience. This has led to a demand for products that can conceal the speakers when viewed from the front of the TV, yet still produce a high-quality audio experience.

[0137] One example of an acoustic device that can be made thinner is a method of vibrating the bezel of a display device by poking it with an actuator containing a rectangular parallelepiped piezoelectric element (the vibration method of the comparative example described with reference to FIG. 9 ). This method allows the actuator to be positioned, for example, in the left-right direction, making it possible to make the display device thinner. However, this method only vibrates the bezel 16 locally, making it difficult to achieve a sufficient sound pressure level. Furthermore, the reproducible frequency range tends to be relatively high-pitched. Furthermore, because the rectangular parallelepiped actuator has a small contact area with the bezel, the sound image perceived by the user is small. Furthermore, while the actuator can push the bezel, it is not configured to pull the bezel, which can potentially reduce the reproducibility of negative ranges in the audio signal.

[0138] In this embodiment, the piezoelectric element 31 is directly fixed to the peripheral component 5 (such as the bezel 16 or rear chassis 17) around the display panel 12 using double-sided tape or adhesive. The piezoelectric element 31 then vibrates the peripheral component 5 by utilizing the force of expansion and contraction in the in-plane direction of the attachment surface 32, and sound is output from the vibrated peripheral component 5. In this method, for example, the entire attachment surface 32 of the piezoelectric element 31 vibrates the peripheral component 5. Therefore, the area through which the vibration is transmitted is larger than when using the above-mentioned actuator, etc., making it possible to realize a relatively large sound image range. As such, in this embodiment, by appropriately arranging the piezoelectric element 31 on the peripheral component 5, it is possible to easily realize the desired sound image representation. As a result, the sense of unity between image and sound is improved, and a realistic acoustic space can be realized.

[0139] Furthermore, since the area for transmitting vibrations is large, it is easy to ensure a sufficient sound pressure level. By utilizing this characteristic, for example, by providing a piezoelectric element 31 on the inner surface 20 of the bezel 16, it becomes possible to generate vibrations in the Z direction as well, thereby increasing the sound pressure level.

[0140] Furthermore, the piezoelectric element 31 is a flat element and can be easily attached to peripheral members other than the bezel 16. Therefore, it is also possible to provide the piezoelectric element 31 on, for example, a peripheral member 5 (the rear chassis 17 in the above example) that is heavier than the bezel 16. This makes it possible to configure a speaker that can reproduce a lower frequency band than the frequency band when the bezel 16 is vibrated. In this way, by appropriately selecting the peripheral member 5, it is possible to expand the reproducible frequency band.

[0141] Furthermore, the piezoelectric element 31 expands and contracts in response to the positive or negative voltage signal, vibrating the peripheral member 5. In other words, even in the negative region of the audio signal, the reproducibility of the audio signal does not decrease. This makes it possible to achieve high-quality audio output that accurately reproduces the audio signal.

[0142] Other Embodiments The present technology is not limited to the above-described embodiments, and various other embodiments can be realized.

[0143] In the above embodiment, the piezoelectric element 31 is attached to the peripheral members 5 of the display panel 12, mainly to the bezel 16 and the rear chassis 17 as vibration targets. However, the present invention is not limited to this, and the piezoelectric element 31 may be attached to other peripheral members 5 as vibration targets.

[0144] For example, the piezoelectric element 31 may be attached to the backlight 15 described with reference to Fig. 2 etc. In this case, for example, the piezoelectric element 31 is disposed behind the backlight 15 so as not to block the emitted light. By using the backlight 15 as the vibration target, it is possible to form a sound image that spreads inside the device.

[0145] Alternatively, the piezoelectric element 31 may be attached to the rear cover 18. Because the rear cover 18 is a member exposed at the rear of the device, the piezoelectric element 31 is disposed, for example, on the inside thereof (on the front side of the rear cover 18). By using the rear cover 18 as the vibration target, it is possible to realize an acoustic space in which sound appears to come from the rear of the device, for example.

[0146] In the above embodiment, a piezoelectric element having a d31 type expansion portion has been described as an example of an expansion element that expands and contracts in the in-plane direction of the attachment surface. The specific configuration of the expansion element is not limited, and any element that can expand and contract in the in-plane direction of the attachment surface may be used.

[0147] For example, a dielectric elastomer that generates strain when an electric field is applied may be used as the expansion element. A linear actuator that expands and contracts in one direction may also be used as the expansion element. In this case, the linear actuator is arranged so that the expansion and contraction direction is along the surface of the member. The type of linear actuator is not limited, and an actuator using a D33 type piezoelectric element may be used, for example. Alternatively, a magnetostrictive actuator, a voice coil motor, or the like may be used.

[0148] Although the above embodiments have been described mainly using image display devices as examples, the present technology can also be applied to devices other than image display devices. For example, the present technology may be applied to devices (so-called sound bars, etc.) used as external speakers for television devices and the like. A sound bar is a device that performs an audio output function by mounting, for example, a dynamic speaker with a moving coil to output audio. In a sound bar, the dynamic speaker is a functional component. In this case, the expansion element is attached to a peripheral component of the dynamic speaker (for example, the frame or housing of the sound bar). This makes it possible, for example, to form a sound image that is difficult to achieve with a dynamic speaker alone or to expand the audio playback range, thereby improving the sound quality of the device and achieving excellent sound image expression. In addition, the present technology is not limited to devices, and can be applied to any device, such as home appliances, service terminals, vehicles, and robots.

[0149] It is also possible to combine at least two of the features of the present technology described above. That is, the various features described in each embodiment may be arbitrarily combined without distinguishing between the embodiments. Furthermore, the various effects described above are merely examples and are not intended to be limiting, and other effects may also be achieved.

[0150] In the present disclosure, the terms "same," "equal," "orthogonal," etc. are concepts that include "substantially the same," "substantially equal," "substantially orthogonal," etc. For example, they also include states that fall within a predetermined range (e.g., a range of ±10%) based on "completely the same," "completely equal," "completely orthogonal," etc.

[0151] The present technology can also adopt the following configurations. (1) An audio output device comprising: a functional component having a predetermined function; a peripheral component arranged around the functional component; a vibration generating unit attached with an attachment surface facing the peripheral component and having one or more expansion elements that expand and contract in an in-plane direction of the attachment surface to vibrate the peripheral component; and a drive unit that expands and contracts the one or more expansion elements based on an audio signal. (2) The audio output device according to (1), wherein the functional component is a display panel, and the audio output device functions as a display device that displays an image using the display panel. (3) The audio output device according to (2), wherein the peripheral component includes a bezel that surrounds an outer edge of the display panel and a rear chassis that supports the display panel from the rear side of the display panel, and the expansion element is attached to at least one of the bezel or the rear chassis. (4) The audio output device according to (3), wherein the bezel has an inner surface facing the outer edge of the display panel, and the expansion element is attached to the inner surface of the bezel. (5) The audio output device according to (4), wherein the inner surface includes a left inner surface provided on a left edge of the bezel and a right inner surface provided on a right edge of the bezel, and the vibration generating unit includes an expansion element arranged on the left inner surface and an expansion element arranged on the right inner surface. (6) The audio output device according to (4) or (5), wherein the inner surface includes an upper inner surface provided on an upper edge of the bezel and a lower inner surface provided on a lower edge of the bezel, and the vibration generating unit includes an expansion element arranged on the upper inner surface and an expansion element arranged on the lower inner surface. (7) The audio output device according to any one of (3) to (6), wherein the rear chassis has a plate-shaped rear portion arranged along the display panel, and the expansion element is attached to the rear portion.(8) The audio output device according to any one of (3) to (7), wherein the rear chassis has a plate-shaped rear portion arranged along the display panel and side portions surrounding the rear portion, and the expansion element is attached to the side portions. (9) The audio output device according to any one of (3) to (8), wherein the rear chassis has a plate-shaped rear portion arranged along the display panel and a protrusion protruding from the rear portion, and the expansion element is attached to the protrusion. (10) The audio output device according to any one of (1) to (9), wherein the expansion element is attached to a surface of the peripheral member that is parallel to or inclined with respect to the front-to-rear direction of the audio output device. (11) The audio output device according to any one of (1) to (10), wherein the expansion element is attached to a surface of the peripheral member that is perpendicular to the front-to-rear direction of the audio output device. (12) The audio output device according to any one of (1) to (11), wherein the expansion element is a piezoelectric element having an expansion portion that forms the attachment surface and expands and contracts along an in-plane direction of the attachment surface. (13) The audio output device according to (12), wherein the expansion portion is a plate-like member that is long in one direction or a plate-like member that has a square planar shape. (14) The audio output device according to (12) or (13), wherein the functional component is a display panel, the peripheral components include a bezel that surrounds an outer edge of the display panel and a rear chassis that supports the display panel from the rear side, and the expansion portion is a plate-like member that is long in one direction and is attached to at least one of the bezel or the rear chassis so that its longitudinal direction is along the up-down direction or the left-right direction of the display panel.(15) The audio output device according to any one of (12) to (14), wherein the functional component is a display panel, the peripheral component includes a bezel surrounding an outer edge of the display panel and a rear chassis supporting the display panel from the rear side, and the expandable portion is a plate-like member that is long in one direction and is attached to at least one of the bezel or the rear chassis so that its longitudinal direction is along the front-to-rear direction of the display panel. (16) The audio output device according to any one of (12) to (15), wherein the vibration generating unit includes a plurality of piezoelectric elements having expandable portions with different shapes. (17) The audio output device according to any one of (12) to (16), wherein the piezoelectric element has a connector substrate to which a signal from the drive unit is input, and a flexible substrate that connects the expandable portion and the connector substrate. (18) The audio output device according to any one of (1) to (17), wherein the vibration generating unit has one or more element groups in which a plurality of expansion elements are connected in parallel or in series.

[0152] DESCRIPTION OF SYMBOLS 5...Peripheral member 11...Display surface 12...Display panel 16...Bezel 17...Rear chassis 20...Inner surface 25...Rear portion 26...Side portion 30...Vibration generating portion 31, 31a, 31b...Piezoelectric element 33...Expandable portion 34...Connector substrate 35...Flexible substrate 45...Protrusion 50...Driver 100, 100a to 100i...Image display device

Claims

1. An audio output device comprising: a functional part having a predetermined function; a peripheral member arranged around said functional part; a vibration generating unit having one or more expansion elements attached with their attachment surface facing said peripheral member and expanding and contracting in the in-plane direction of said attachment surface to vibrate said peripheral member; and a driving unit that expands and contracts said one or more expansion elements based on an audio signal.

2. An audio output device according to claim 1, wherein the functional component is a display panel, and the audio output device functions as a display device that displays images using the display panel.

3. An audio output device according to claim 2, wherein the peripheral members include a bezel that surrounds the outer edge of the display panel and a rear chassis that supports the display panel from the rear side of the display panel, and the elastic element is attached to at least one of the bezel or the rear chassis.

4. An audio output device according to claim 3, wherein the bezel has an inner surface facing the outer edge of the display panel, and the elastic element is attached to the inner surface of the bezel.

5. An audio output device according to claim 4, wherein the inner surfaces include a left inner surface provided on the left edge of the bezel and a right inner surface provided on the right edge of the bezel, and the vibration generating unit includes an expansion element disposed on the left inner surface and an expansion element disposed on the right inner surface.

6. An audio output device according to claim 4, wherein the inner surface includes an upper inner surface provided on the upper edge of the bezel and a lower inner surface provided on the lower edge of the bezel, and the vibration generating unit includes an expansion element arranged on the upper inner surface and an expansion element arranged on the lower inner surface.

7. An audio output device according to claim 3, wherein the rear chassis has a plate-shaped rear portion arranged along the display panel, and the elastic element is attached to the rear portion.

8. An audio output device according to claim 3, wherein the rear chassis has a plate-shaped rear section arranged along the display panel and side sections surrounding the rear section, and the elastic element is attached to the side sections.

9. An audio output device according to claim 3, wherein the rear chassis has a plate-shaped rear portion arranged along the display panel and a protruding portion protruding from the rear portion, and the elastic element is attached to the protruding portion.

10. An audio output device according to claim 1, wherein the elastic element is attached to a surface of the peripheral member that is parallel to or inclined with respect to the front-to-rear direction of the audio output device.

11. An audio output device according to claim 1, wherein the elastic element is attached to a surface of the peripheral member that is perpendicular to the front-to-rear direction of the audio output device.

12. An audio output device according to claim 1, wherein the expansion element is a piezoelectric element that forms the attachment surface and has an expansion portion that expands and contracts along the in-plane direction of the attachment surface.

13. An audio output device according to claim 12, wherein the expandable portion is a plate-like member that is long in one direction or a plate-like member whose planar shape is square.

14. An audio output device as claimed in claim 12, wherein the functional component is a display panel, the peripheral components include a bezel surrounding the outer edge of the display panel and a rear chassis supporting the display panel from the rear side, and the expandable portion is a plate-like member that is long in one direction and is attached to at least one of the bezel or the rear chassis so that its longitudinal direction is aligned with the vertical or horizontal direction of the display panel.

15. An audio output device as claimed in claim 12, wherein the functional component is a display panel, the peripheral components include a bezel surrounding the outer edge of the display panel and a rear chassis supporting the display panel from the rear side, and the expandable portion is a plate-like member that is long in one direction and is attached to at least one of the bezel or the rear chassis so that its longitudinal direction is aligned with the front-to-rear direction of the display panel.

16. An audio output device according to claim 12, wherein the vibration generating section includes a plurality of piezoelectric elements whose expansion and contraction sections have different shapes.

17. An audio output device according to claim 12, wherein the piezoelectric element has a connector board to which a signal from the drive unit is input, and a flexible board that connects the expansion / contraction unit and the connector board.

18. An audio output device according to claim 1, wherein the vibration generating unit has one or more element groups in which a plurality of expansion elements are connected in parallel or in series.

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