FLEXIBLE VIBRATION MODULE AND DISPLAY DEVICE INCLUDING THE SAME

Abstract

A flexible vibration module with improved piezoelectric properties, rigidity, and flexibility, and a display device including the same are provided. The display device includes a flexible vibration module (300) and a display panel. The flexible vibration module includes a piezoelectric composite layer (310) having a plurality of piezoelectric portions (311) with piezoelectric properties and flexible portions (313) between the plurality of piezoelectric portions, at least two of which have different sizes. The display panel includes a display area configured to display an image and vibrate in response to vibration of the flexible vibration module.

Description

[Technical field]

[0001] The present specification relates to a display device, and more particularly to a flexible vibration module and a display device including the same. [Background technology]

[0002] A display device generally requires a separate speaker to be installed in order to display an image on a display panel and provide sound, and when a speaker is installed in a display device, the speaker takes up space, which causes a problem of constraints on the design and spatial arrangement of the display device.

[0003] The speaker applied to the display device may be, for example, an actuator including a magnet and a coil. However, since the thickness of the actuator is thick, a piezoelectric element having a smaller thickness may be used. Since the piezoelectric element is fragile, the piezoelectric element may be easily damaged by an external impact, which may result in low reliability of sound reproduction. Summary of the Invention

[0004] Speakers applied to display devices can be implemented using a film-type vibration module. Film-type vibration modules can be manufactured in a large area and therefore can be applied to large-area display devices. However, film-type vibration modules have problems in that they are difficult to apply to large areas due to their low piezoelectric properties and low vibration. When implemented using ceramics to improve the piezoelectric properties, problems arise in that durability is poor and the size of the ceramic is limited.

[0005] A vibration module made of a piezoelectric composite including a piezoelectric ceramic can be applied to a display device. As a result, the piezoelectric composite layer mainly vibrates in the lateral (or horizontal) direction of the display device, which may make it difficult to sufficiently vibrate the display device in the vertical direction. As a result, the display device cannot output the desired sound to the front area of ​​the display device. Alternatively, when a film-type piezoelectric is applied to a display device, the sound pressure characteristics may be lower than those of a general speaker such as an exciter. According to one example, when a laminated film-type piezoelectric composed of multiple layers of film-type piezoelectric is applied to a display device to improve sound pressure, there is a problem of increased power consumption.

[0006] The vibration module can improve the piezoelectric properties, rigidity, and flexibility. The vibration module can be formed of a composite layer including a filler having a high dielectric constant and low piezoelectric properties. As a result, the vibration module may not realize the desired sound. According to an embodiment of the present application, the vibration module can be formed of a piezoelectric ceramic formed of an organic substance (or organic material) having piezoelectric properties to improve rigidity and flexibility.

[0007] In other embodiments of the present application, the vibration module may be formed of a piezoelectric ceramic having piezoelectric properties and a substance (or material) such as a polymer (or polymer) to reduce the brittleness of the piezoelectric ceramic. In these exemplary embodiments, the vibration module may be configured such that the polymer-like substance is configured into the piezoelectric ceramic composite, thereby making the vibration module flexible.

[0008] In another embodiment of the present application, the vibration module can have various vibration frequencies, the sound pressure characteristics can be improved, and the sound reproduction band can be expanded. In an embodiment of the present application, the display device can include a vibration module having a structure for improving piezoelectric characteristics, rigidity, and flexibility.

[0009] An object of the present invention is to provide a flexible vibration module having improved piezoelectric properties, rigidity, and flexibility, and a display device including the same.

[0010] The problem to be solved in one embodiment of the present specification is to provide a flexible vibration module and a display device including the same, in which sound pressure characteristics can be improved through various vibration frequencies and the sound reproduction band can be expanded.

[0011] An object of the present invention is to provide a display device capable of outputting sound generated by vibration of a display panel to the front of the display panel.

[0012] A flexible vibration module according to one embodiment of the present specification includes a piezoelectric composite layer including a plurality of piezoelectric portions having piezoelectric properties and a soft portion between the plurality of piezoelectric portions, and at least two of the plurality of piezoelectric portions have different sizes.

[0013] A flexible vibration module according to one embodiment of this specification includes a piezoelectric composite layer including a plurality of piezoelectric portions having piezoelectric properties and a flexible portion between the plurality of piezoelectric portions, and the piezoelectric composite layer has a plurality of vibration frequencies (or natural frequencies).

[0014] A display device according to an embodiment of the present specification includes a flexible vibration module and a display panel. The flexible vibration module includes a piezoelectric composite layer having a plurality of piezoelectric parts having piezoelectric properties and a flexible part between the plurality of piezoelectric parts, at least two of the plurality of piezoelectric parts having different sizes, and the display panel includes a display area configured to display an image and vibrate due to vibration of the flexible vibration module.

[0015] A display device according to an embodiment of the present specification includes a flexible vibration module and a display panel. The flexible vibration module includes a piezoelectric composite layer having a plurality of piezoelectric parts having piezoelectric properties and a flexible part between the plurality of piezoelectric parts, the piezoelectric composite layer having a plurality of vibration frequencies (or natural frequencies), and the display panel includes a display area configured to display an image and vibrate due to the vibration of the flexible vibration module.

[0016] According to an embodiment of the present specification, the display panel may be vibrated by vibration of a flexible vibration module disposed on a rear surface of the display panel, and as a result, sound generated by the vibration of the display panel may be output in front of the display panel.

[0017] According to an embodiment of the present specification, most of the area of ​​the display panel can be vibrated by a large-area flexible vibration module in the form of a film, which further improves the localization of sound caused by the vibration of the display panel, thereby realizing a stereophonic effect.

[0018] According to an embodiment of the present specification, the display panel can vibrate at various frequencies (or natural frequencies) by driving the flexible vibration module to output sound, thereby increasing the sound pressure characteristics of the sound and expanding the sound reproduction band.

[0019] In addition to the above-mentioned effects, other features and advantages of the present invention will be apparent to those skilled in the art from the following description and from such description and explanation. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a perspective view of a display device according to an embodiment of the present specification. [Diagram 2] 2 is a cross-sectional view taken along line II' shown in FIG. 1. [Diagram 3] FIG. 2 illustrates a flexible vibration module according to a first embodiment of the present specification. [Figure 4] 4 is a cross-sectional view taken along line II-II' shown in FIG. 3. [Diagram 5] FIG. 11 is a diagram showing a flexible vibration module according to a second embodiment of the present specification. [Figure 6] FIG. 13 is a diagram showing a flexible vibration module according to a third embodiment of the present specification. [Figure 7] FIG. 13 is a diagram showing a flexible vibration module according to a fourth embodiment of the present specification. [Figure 8] 8 is a cross-sectional view taken along line III-III' shown in FIG. 7. [Figure 9] FIG. 13 is a diagram showing a flexible vibration module according to a fifth embodiment of the present specification. [Figure 10] 10 is a cross-sectional view taken along line IV-IV' shown in FIG. 9. [Figure 11] 10A and 10B are diagrams illustrating a modified example of the flexible vibration module illustrated in FIG. [Figure 12] 2 is another cross-sectional view of the line II' shown in FIG. 1. [Figure 13] 13 is a diagram showing the flexible vibration module and a partition shown in FIG. 12. FIG. [Figure 14] 13 is a diagram showing the flexible vibration module and a partition shown in FIG. 12. FIG. [Figure 15a] 15A and 15B are diagrams showing modified examples of the first and second flexible vibration modules shown in FIG. 14. [Figure 15b] 15A and 15B are diagrams showing modified examples of the first and second flexible vibration modules shown in FIG. 14. [Figure 15c] 15A and 15B are diagrams showing modified examples of the first and second flexible vibration modules shown in FIG. 14. [Figure 16a] 1A to 1C are diagrams illustrating various display devices to which a flexible vibration module according to an embodiment of the present disclosure can be applied. [Figure 16b] 1A to 1C are diagrams illustrating various display devices to which a flexible vibration module according to an embodiment of the present disclosure can be applied. [Figure 16c]1A to 1C are diagrams illustrating various display devices to which a flexible vibration module according to an embodiment of the present disclosure can be applied. [Figure 17] 1 is a graph showing measured sound pressure characteristics of a display panel according to an embodiment of the present specification and a display panel according to a comparative example; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The advantages and features of the present specification, and the methods for achieving them, will become clear from the following detailed description of the embodiments in conjunction with the accompanying drawings. However, the present specification is not limited to the embodiments disclosed below, and may be embodied in various different forms. The embodiments are provided merely to complete the disclosure of the present specification and to fully inform those skilled in the art of the invention to which the present specification pertains.

[0022] The shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of the present specification are illustrative, and the present specification is not limited to the matters shown in the drawings. The same reference numerals refer to the same components throughout the specification. In addition, in describing the present specification, if a detailed description of related publicly known technology may unnecessarily obscure the gist of the specification, the detailed description may be omitted.

[0023] When the terms "including," "having," "consisting of," and the like are used herein, other parts may be added unless "only" is used. When an element is expressed in the singular, the plural is included unless otherwise expressly stated.

[0024] When interpreting elements, they are to be interpreted as including a range of error even if there is no explicit statement to the contrary.

[0025] When describing a location relationship between two parts, for example "on top of", "on top of", "on bottom of", "next to", etc., one or more other parts may be located between the two parts, unless "immediately" or "directly" is used.

[0026] When describing a temporal relationship, for example when the temporal sequence is described using "after", "following", "next to", "before", etc., non-consecutive cases can also be included, as long as "immediately" or "directly" is not used.

[0027] Although the terms "first", "second" and the like are used to describe various components, these components are not limited by these terms. These terms are used only to distinguish one component from another. Therefore, the first component described below may be the second component within the technical concept of this specification.

[0028] The term "at least one" should be understood to include all combinations that can be presented from a plurality of relevant items. For example, the meaning of "at least one of the first, second and third items" can mean not only the first, second or third item, respectively, but also all combinations of items that can be presented from two or more of the first, second and third items.

[0029] The features of each of the examples in this specification may be partially or wholly combined or combined with each other, and each example may be implemented independently of each other, or may be implemented together in a related relationship.

[0030] The same elements may be designated by the same reference numerals even when they are shown in different drawings, and the scales of the elements shown in the accompanying drawings may be different from the actual scales for the convenience of explanation, and therefore are not limited to the scales shown in the drawings.

[0031] FIG. 1 is a perspective view of a display device according to an embodiment of the present specification, and FIG. 2 is a cross-sectional view taken along line II' in FIG.

[0032] 1 and 2, a display device according to an embodiment of the present specification may include a display panel 100 and a flexible vibration module 300 disposed on a rear surface of the display panel 100.

[0033] The display panel 100 may be any type of display panel or curved display panel, such as a liquid crystal display panel, an organic light-emitting display panel, a quantum dot light-emitting display panel, a micro light-emitting diode display panel, and an electrophoretic display panel. For example, the display panel 100 according to the present specification is not limited to a specific display panel as long as it can generate sound waves (or acoustic) or generate haptic feedback in response to touch by vibrating with the flexible vibration module 300.

[0034] In some embodiments, the display panel 100 may include a plurality of pixels defined by a plurality of gate lines and a plurality of data lines, a thin film transistor array substrate including a thin film transistor in each pixel to drive each pixel, a light emitting element layer on the thin film transistor array substrate, and an encapsulation substrate covering the light emitting element layer, etc. For example, the encapsulation substrate may protect the thin film transistor and the light emitting element layer, etc. from external impact and prevent moisture from penetrating into the light emitting element layer.

[0035] The display panel 100 may include a display area that displays an image by driving each of a plurality of pixels, and a non-display area that surrounds the display area.

[0036] The display panel 100 may have a curved shape or may be curved to have a certain radius of curvature or may include a curved portion.

[0037] The bending portion of the display panel 100 may be at least one of one side end and the other side end, which are arranged side by side. The one side end and / or the other side end of the display panel 100 implementing the bending portion may include only the non-display area, or may include the edge of the display area and the non-display area. The display panel including the bending portion implemented by bending the non-display area may have a one-sided bezel bending structure or a two-sided bezel bending structure. In addition, the display panel including the bending portion implemented by bending the edge of the display area and the non-display area may have a one-sided active bending structure or a two-sided active bending structure.

[0038] The display device according to an embodiment of the present disclosure may further include a functional film 130 disposed on the display panel 100 .

[0039] The functional film 130 may be disposed on the front surface of the display panel 100. In some embodiments, the functional film 130 may be attached to the front surface of the display substrate 100 using a film adhesive. In some embodiments, the film adhesive may include a pressure sensitive adhesive (PSA), an optically clear adhesive (OCA), or an optically clear resin (OCR).

[0040] The functional film 130 may include at least one of an anti-reflection layer (or anti-reflection film) for preventing reflection of external light, a barrier layer (or barrier film) for primarily preventing the penetration of moisture or oxygen, and an optical path control layer (or optical path control film) for controlling the path of light (or viewing angle).

[0041] The display device according to the embodiments of the present specification may further include a touch panel (or a touch electrode layer) for sensing a user's touch on the display panel 100. For example, the touch panel is disposed to overlap with the display area and serves as a touch sensor for sensing a user's touch on the display panel 100. For example, the touch panel may be disposed between the light emitting element layer and the encapsulation substrate, or between the display panel 100 and the functional film 130. Such a touch panel may include a plurality of touch electrodes for sensing a change in capacitance due to a user's touch using a mutual capacitance method or a self-capacitance method.

[0042] The flexible vibration module 300 can be disposed on the rear (or back or underside) of the display panel 100 to vibrate the display panel 100. The flexible vibration module 300 can be in the form of a thin film having various vibration frequencies (or natural vibration frequencies or natural frequencies) due to piezoelectric characteristics and relatively high flexibility. For example, the flexible vibration module 300 can have a thickness thinner than the display panel 100. The flexible vibration module 300 can be expressed as a sound generating module, a sound generating device, a film actuator, a film type piezoelectric composite actuator, a film speaker, a film type piezoelectric speaker, a film type piezoelectric composite speaker, or the like. The flexible vibration module 300 can use the display panel 100 as a diaphragm.

[0043] The flexible vibration module 300 may be made of piezoelectric ceramics having piezoelectric properties. To complement the impact resistance of the piezoelectric ceramics and realize flexibility, the flexible vibration module 300 may be made of a material such as a polymer within the piezoelectric ceramics. In some embodiments, the flexible vibration module 300 may include a piezoelectric ceramic having a perovskite crystal structure, thereby vibrating (or exhibiting mechanical displacement) in response to an externally applied electrical signal.

[0044] The flexible vibration module 300 can vibrate the display panel 100 at various vibration frequencies by vibrating according to an electric signal. For example, the flexible vibration module 300 can vibrate the display panel 100 by vibrating according to a voice signal synchronized with an image displayed on the display panel 100. Sound generated by the vibration of the display panel 100 can have various vibration frequencies and can have improved sound pressure characteristics due to the vibration of the flexible vibration module 300. The vibration of the flexible vibration module 300 can expand the sound reproduction band. As one embodiment, the flexible vibration module 300 can vibrate the display panel 100 by vibrating according to a haptic feedback signal (or a tactile feedback signal) synchronized with a user's touch on a touch panel arranged on the display panel 100. Therefore, the display panel 100 can vibrate according to the vibration of the flexible vibration module 300 to provide at least one of sound and tactile feedback to the user (or viewer).

[0045] The flexible vibration module 300 according to the embodiment may have a size corresponding to the display area of ​​the display panel 100. The size of the flexible vibration module 300 may be 0.9 to 1.1 times the size of the display area. For example, the size of the flexible vibration module 300 may be the same or approximately the same as the display area of ​​the display panel 100, so that it can cover most of the display panel 100, and the vibration generated by the flexible vibration module 300 can vibrate the entire display panel 100, so that the localization of the sound is high and the satisfaction of the user can be improved. The contact area (or panel coverage) between the display panel 100 and the flexible vibration module 300 can be increased, so that the vibration area of ​​the display panel 100 can be increased. This can improve the deep bass range sound generated by the vibration of the display panel 100. In the case of a large display device, since the entire large (or large area) display panel 100 can be vibrated, the localization of the sound caused by the vibration of the display panel 100 can be improved and a stereophonic effect can be realized.

[0046] In some embodiments, the flexible vibration module 300 can be attached to the rear surface of the display panel 100 by an adhesive member 200 (or a module adhesive member).

[0047] The adhesive member 200 may be interposed between the rear surface of the display panel 100 and the flexible vibration module 300. For example, the adhesive member 200 may be a double-sided tape or adhesive including an adhesive layer having high adhesion to each of the rear surface of the display panel 100 and the flexible vibration module 300. For example, the adhesive layer of the adhesive member 200 may include, but is not limited to, epoxy, acrylic, silicon, or urethane. The adhesive layer of the adhesive member 200 may further include an additive such as a tackifier, a wax component, or an antioxidant, and the additive may prevent the adhesive member 200 from falling (or peeling) from the display panel 100 due to the vibration of the flexible vibration module 300. For example, the tackifier may be a rosin derivative, the wax component may be paraffin wax, and the antioxidant may be a phenol-based antioxidant such as thiolester.

[0048] The adhesive member 200 according to another embodiment may further include a hollow portion provided between the display panel 100 and the flexible vibration module 300. The hollow portion of the adhesive member 200 provides an air gap between the display panel 100 and the flexible vibration module 300. The air gap allows sound waves (or sound pressure) caused by the vibration of the flexible vibration module 300 to be concentrated on the display panel 100 without being dispersed by the adhesive member 200. Therefore, it is possible to minimize vibration loss caused by the adhesive member 200 and increase the sound pressure characteristics of the sound generated by the vibration of the display panel 100.

[0049] The display device according to an embodiment of the present disclosure may further include a rear structure 500 supporting the display panel 100 .

[0050] The rear structure 500 may be expressed by other terms such as, but not limited to, a rear cover, a cover bottom, a plate bottom, a back cover, a base frame, a metal frame, a metal chassis, a chassis base, or an m-chassis. Therefore, the rear structure 500 may be any type of frame or plate-like structure disposed on the rear of the display device as a support for supporting the display panel 100.

[0051] The rear structure 500 according to an embodiment may include a first rear cover 510 and a second rear cover 550 .

[0052] The first rear cover 510 may be a plate-like member covering the entire rear surface of the display panel 100. The first rear cover 510 may be separated from the rearmost surface of the display panel 100 with a gap space (GS) therebetween. For example, the gap space (GS) may be expressed as an air gap, a vibration space, an acoustic resonator, or the like, and is not limited to the terminology.

[0053] The second rear cover 550 may be a plate-like member that is disposed on the rear surface of the first rear cover 510 and covers the entire rear surface of the first rear cover 510 .

[0054] The first rear cover 510 and the second rear cover 550 may be joined or connected to each other via a cover connecting member 530. For example, the cover connecting member 530 may be an adhesive resin, a double-sided tape, or a double-sided adhesive foam pad, and may have elasticity for shock absorption. As an example, the cover connecting member 530 may be interposed over the entire area between the first rear cover 510 and the second rear cover 550. As another example, the cover connecting member 530 may have a mesh structure having an air gap between the first rear cover 510 and the second rear cover 550.

[0055] The display device according to an embodiment of the present specification may further include a middle frame 600 .

[0056] The middle frame 600 may be disposed between the rear end (or the periphery, edge or near edge of the rear) of the display panel 100 and the front end (or the periphery, edge or near edge of the front) of the rear structure 500. The middle frame 600 may support the respective edges or peripheries of the display panel 100 and the rear structure 500 and surround the respective edges or peripheries of the display panel 100 and the rear structure 500. The middle frame 600 provides a gap space (GS) between the display panel 100 and the rear structure 500. Such a middle frame 600 may be expressed as a middle cabinet, a middle cover, a middle chassis, or the like, and is not limited to these terms.

[0057] According to an embodiment, the middle frame 600 may include a support portion 610 and a side wall portion 630 .

[0058] The support 610 is interposed between the rear end (or the periphery, edge or near edge of the rear) of the display panel 100 and the front end (or the periphery, edge or near edge of the front) of the rear structure 500, thereby providing a gap space (GS) between the display panel 100 and the rear structure 500. The front side of the support 610 is coupled (or connected) to the rear end (or the periphery, edge or near edge of the rear) of the display panel 100 via a first adhesive member 601, and the rear side of the support 610 is coupled (or connected) to the front end (or the periphery of the front) of the rear structure 500 via a second adhesive member 603. For example, the support 610 may have a single frame structure in a rectangular shape or a shape of multiple dividing bars.

[0059] The side wall 630 is vertically coupled (or connected) to an outer surface of the support 610 so as to be aligned with the thickness direction (Z) of the display device. The side wall 630 can protect the outer surfaces of the display panel 100 and the rear structure 500 by surrounding the entire outer surfaces of the display panel 100 and the rear structure 500. According to an embodiment, the support 610 and the side wall 630 can have a frame structure having a cross-sectional structure in the shape of a "-" or a vertical cross-sectional structure by being connected (or connected) to each other to form a single housing.

[0060] A display device according to an embodiment of the present disclosure may include a panel connecting member instead of the middle frame 600 .

[0061] The panel connecting member may be interposed between the rear end (or the periphery, edge or near edge of the rear) of the display panel 100 and the front end (or the periphery, edge or near edge of the front) of the rear structure 500, thereby providing a gap space (GS) between the display panel 100 and the rear structure 500. Such a panel connecting member may be disposed between the rear end (or the periphery, edge or near edge of the rear) of the display panel 100 and the end (or the periphery, edge or near edge) of the rear structure 500 to bond the display panel 100 and the rear structure 500. For example, the panel connecting member may be implemented as a double-sided tape, a single-sided tape, or a double-sided adhesive foam pad.

[0062] When the display device includes a panel connecting member instead of the middle frame 600, the rear structure 500 may include a side wall covering portion that is bent from the end of the second rear cover 550 to surround the entire outer surfaces (or outer walls) of the first rear cover 510, the panel connecting member, and the display panel 100. The side wall covering portion according to an example may have a single side wall structure or a hemming structure. The hemming structure may be a structure in which the end of a certain member is bent into a curved shape to overlap each other or be spaced apart from each other.

[0063] In the display device according to the embodiment of the present specification, sound may be generated by vibration of the display panel 100 due to vibration of the flexible vibration module 300 arranged on the rear surface of the display panel 100. The sound may be output to the front (FD) of the display panel 100, thereby improving the immersive feeling of a viewer viewing an image displayed on the display panel 100. The large-area flexible vibration module 300 in the form of a film may vibrate most of the area of ​​the display panel 100. Therefore, the localization of sound caused by the vibration of the display panel 100 may be further improved, realizing a stereophonic effect.

[0064] In some embodiments, the display panel 100 can be vibrated by driving the flexible vibration module 300 having various vibration frequencies to output sound. Therefore, the sound pressure characteristics of the sound can be increased and the sound reproduction band can be expanded. In some embodiments, even without configuring a separate haptic driving device, the display panel 100 can be vibrated by the vibration of the flexible vibration module 300 disposed on the rear surface of the display panel 100 to provide the user with haptic feedback in response to the user's touch on the display panel 100.

[0065] FIG. 3 is a diagram showing a flexible vibration module according to a first embodiment of the present specification, and FIG. 4 is a cross-sectional view of line II-II' shown in FIG. 3, which shows the flexible vibration module shown in FIG. 2.

[0066] 3 and 4, a flexible vibration module 300 according to a first embodiment of the present disclosure may include a piezoelectric composite layer 310, a first electrode layer 320, and a second electrode layer 330.

[0067] The piezoelectric composite layer 310 may be embodied in the form of a thin film having various vibration frequencies (or natural frequencies or natural vibration frequencies) due to piezoelectric properties and relatively high flexibility.

[0068] The piezoelectric composite layer 310 according to an embodiment may include a plurality of piezoelectric portions 311 and a flexible portion 313 disposed between the plurality of piezoelectric portions 311. The plurality of piezoelectric portions 311 and the flexible portion 313 may be disposed on the same plane (or in the same layer). For example, the piezoelectric composite layer 310 may be ensured to have piezoelectric properties and flexibility.

[0069] The piezoelectric composite layer 310 may have various shapes depending on the arrangement of the piezoelectric parts 311 and the flexible parts 313. For example, the piezoelectric composite layer 310 may have a rectangular shape, a circular shape, an elliptical shape, or a polygonal shape.

[0070] Each of the piezoelectric parts 311 may include a polygonal pattern. For example, each of the piezoelectric parts 311 may be a line pattern having a first width (W1), spaced apart from each other along a first direction (X) and arranged side by side in a second direction (Y).

[0071] According to an embodiment, at least one of the plurality of piezoelectric portions 311 may have different sizes. The size of the piezoelectric portion 311 may be defined by any one of length, width, thickness, area, and volume. As an embodiment, some of the plurality of piezoelectric portions 311 may have the same size within a range of process error (or tolerance) occurring in a manufacturing process, and the remaining portions may have different sizes. As another embodiment, each of the plurality of piezoelectric portions 311 may have a different size. For example, at least one of the plurality of piezoelectric portions may have a different length, a different width, or a different thickness.

[0072] At least one of the multiple piezoelectric parts 311 according to other embodiments may have another vibration frequency (or natural frequency or natural vibration frequency). As an example, some of the multiple piezoelectric parts 311 may have the same vibration frequency, and the rest may have different vibration frequencies. As another example, each of the multiple piezoelectric parts 311 may have a different vibration frequency.

[0073] Each of the plurality of piezoelectric parts 311 may have a symmetrical structure with respect to a first middle part (CP1) (or a lateral center line) of the piezoelectric composite layer 310 along the first direction (X). According to an embodiment, each of the plurality of piezoelectric parts 311 may have a size that gradually increases from both ends (EP1, EP2) of the piezoelectric composite layer 310 to the first middle part (CP1) along the first direction (X). Therefore, the plurality of piezoelectric parts 311 may have various vibration frequencies corresponding to various sizes (or size gradients).

[0074] Each of the plurality of piezoelectric portions 311 may vibrate in a vibration mode with a displacement (or direction) of d31. As an example, the vibration frequency of the piezoelectric portion 311 is inversely proportional to the weight (or mass) and may therefore increase or decrease depending on the weight of the piezoelectric portion 311, which depends on the length of the piezoelectric portion 311. For example, if the length of the piezoelectric portion 311 decreases, the vibration frequency of the piezoelectric portion 311 may increase due to the decrease in weight. If the length of the piezoelectric portion 311 increases, the vibration frequency of the piezoelectric portion 311 may decrease due to the increase in weight.

[0075] In another embodiment, the resonant frequency of the piezoelectric part 311 may be adjusted according to the length or rigidity, and may increase or decrease according to the length. For example, when the length of the piezoelectric part 311 is decreased, the primary resonant frequency of the piezoelectric part 311 increases with the decrease in length, and when the length of the piezoelectric part 311 is increased, the primary resonant frequency of the piezoelectric part 311 decreases with the increase in length. As an example, when the length (L) of the piezoelectric part 311 is 50 mm, the wavelength (λ) is 100 nm, and the sound wave speed (υ) is 1000 m / s, the primary resonant frequency (f1=υ / λ) (λ=2L) of the piezoelectric part 311 may be 10 kHz, and when the length (L) of the piezoelectric part 311 is decreased to 25 mm, the primary resonant frequency (f1) of the piezoelectric part 311 may increase to 20 kHz.

[0076] The piezoelectric composite layer 310 according to the embodiment can have various vibration frequencies because the size of each of the piezoelectric parts 311 increases from both ends (EP1, EP2) to the first middle part (CP1). Therefore, the sound pressure characteristic and sound pressure flattening characteristic (or flatness) of the sound generated by the vibration of the display panel 100 can be increased, and the reproduction band of the sound range can be expanded.

[0077] In some embodiments, the piezoelectric composite layer 310 may include 1st to Nth (N is an odd number equal to or greater than 5) piezoelectric portions (311[1] to 311[N]). The i+1th (i is (N-1) / 2) piezoelectric portion (311[i+1]) is disposed in a first intermediate portion (CP1) of the piezoelectric composite layer 310, and the 1st to ith piezoelectric portions (311[1] to 311[i]) are disposed on a first side surface (S1) between one end (EP1) of the piezoelectric composite layer 310 and the first intermediate portion (CP1). The i+2th to Nth piezoelectric portions (311[i+2] to 311[N]) may be disposed on a second side surface (S2) between the other end (EP2) opposite to the one end (EP1) of the piezoelectric composite layer 310 and the first intermediate portion (CP1). Of the first to Nth piezoelectric portions (311[1] to 311[N]), the remaining piezoelectric portions except for the i+1th piezoelectric portion have a top-bottom asymmetric structure aligned with the second direction (Y) with respect to the second middle portion (CP2) (or the vertical center line) of the piezoelectric composite layer 310. As a result, one end of the remaining piezoelectric portions of the first to Nth piezoelectric portions (311[1] to 311[N]), except for the i+1th piezoelectric portion (311[i+1]), may be spaced apart from one side (or upper side) of the piezoelectric composite layer 310 aligned with the first direction (X).

[0078] According to an embodiment, each of the first to Nth piezoelectric portions 311 may have the same width (W1) and thickness (H1) (or height) within a range of process error (or allowable error) occurring in a manufacturing process. The (i+1)th piezoelectric portion (311[i+1]) may have the longest length among the piezoelectric portions 311, and may have, for example, a first length (L1) corresponding to the vertical length of the piezoelectric composite layer 310 along the second direction (Y). Each of the first piezoelectric portion (311[1]) and the Nth piezoelectric portion (311[N]) may be disposed closest to the tip of the piezoelectric composite layer 310 and may have the shortest length among the piezoelectric portions 311, and may have, for example, a second length (L2) shorter than the first length (L1) of the (i+1)th piezoelectric portion (311[i+1]).

[0079] The 2nd to i'th piezoelectric portions (311[2] to 311[i]) may have different lengths within a range longer than the first piezoelectric portion (311[1]) and shorter than the i+1'th piezoelectric portion (311[i+1]), and may have longer lengths as they approach the i+1'th piezoelectric portion (311[i+1]). The i+2nd to N-1'th piezoelectric portions (311[i+2] to 311[N-1]) may have different lengths within a range longer than the N'th piezoelectric portion (311[N]) and shorter than the i+1'th piezoelectric portion (311[i+1]), and may have longer lengths as they approach the i+1'th piezoelectric portion (311[i+1]). Therefore, the 1st to i+1th piezoelectric portions (311[1] to 311[i+1]) can have different frequencies due to their different sizes (or lengths), and the i+2nd to Nth piezoelectric portions (311[i+2] to 311[N]) can have different frequencies due to their different sizes (or lengths). Of the 1st to Nth piezoelectric portions (311[1] to 311[N]), the piezoelectric portions having a symmetrical structure with respect to the i+1th piezoelectric portion (311[i+1]) can have the same frequency.

[0080] According to an embodiment, the plurality of piezoelectric units 311 may be grouped into a plurality of groups (or piezoelectric groups). Each of the plurality of groups may include the same or different number of piezoelectric units 311. The piezoelectric units 311 arranged in each group may have the same size within a range of process error (or tolerance) occurring in a manufacturing process. Each of the plurality of piezoelectric units 311 may have a different size for each group. For example, each of the plurality of piezoelectric units 311 may have the same width and thickness (or height) within a range of process error (or tolerance) occurring in a manufacturing process, and may have a different length for each group. Thus, each of the plurality of groups may have a different vibration frequency.

[0081] According to an embodiment, each of the plurality of groups may include two or more piezoelectric parts 311 from among the plurality of piezoelectric parts 311. The two or more piezoelectric parts 311 of each group may be disposed adjacent to each other or may be disposed in a bilaterally symmetrical structure based on a first middle part (CP1) of the piezoelectric composite layer 310. The piezoelectric parts disposed in the remaining groups, excluding the group disposed in the first middle part (CP1) of the piezoelectric composite layer 310, may be disposed in a vertically asymmetrical structure based on a second middle part (CP2) of the piezoelectric composite layer 310. For example, when the piezoelectric composite layer 310 includes first to seventeenth piezoelectric parts (311[1] to 311[N]) as shown in FIG. 3, the 17 piezoelectric parts (311[1] to 311[N]) may be grouped into first to ninth groups. The first group may include one piezoelectric portion disposed in the first intermediate portion (CP1) of the piezoelectric composite layer 310, and each of the second to ninth groups may include two piezoelectric portions, and the two piezoelectric portions included in each of the second to ninth groups may be disposed in a symmetrical structure with respect to the first intermediate portion (CP1) of the piezoelectric composite layer 310. For example, the first group may include a ninth piezoelectric portion (311[i+1]) having the longest length (L1) and disposed in the first intermediate portion (CP1) of the piezoelectric composite layer 310, the second group may include an eighth piezoelectric portion (311[i]) and a tenth piezoelectric portion (311[i+2]) closest to the first group, and the ninth group may include a first piezoelectric portion (311[1]) closest to one end (EP1) of the piezoelectric composite layer 310 and a seventeenth piezoelectric portion (311[N]) closest to the other end (EP2) of the piezoelectric composite layer 310. Therefore, each of the first to ninth groups may have a different vibration frequency due to the piezoelectric portions 311 having different sizes for each group, and the vibration frequencies for each group may be symmetrical about the first middle portion (CP1) of the piezoelectric composite layer 310.

[0082] According to an embodiment, each of the piezoelectric parts 311 may include an inorganic material or a piezoelectric material that vibrates due to a piezoelectric effect (or piezoelectric characteristics) caused by an electric field. For example, each of the piezoelectric parts 311 may be expressed as an electroactive part, an inorganic material part, a piezoelectric material part, or a vibration part.

[0083] Each of the piezoelectric parts 311 may be made of a ceramic-based material capable of realizing a relatively high vibration, or may be made of a piezoelectric ceramic having a perovskite-based crystal structure. For example, the inorganic material part of each of the piezoelectric parts 311 may include one or more of lead (Pb), zirconium (Zr), titanium (Ti), zinc (Zn), nickel (Ni), manganese (Mn), and niobium (Nb). As another example, the inorganic material part of each of the piezoelectric parts 311 may include a PZT (lead zirconate titanate)-based material including lead (Pb), zirconium (Zr), and titanium (Ti), or a PZNN (lead zirconate nickel niobate)-based material including lead (Pb), zinc (Zn), nickel (Ni), and niobium (Nb). Also, the inorganic material portion may include at least one of CaTiO3, BaTiO3, and SrTiO3 that do not contain lead (Pb). The piezoelectric portions 311 having such a configuration may alternately repeat contraction and expansion due to the inverse piezoelectric effect caused by the applied signal. Therefore, the piezoelectric portions 311 may vibrate in a vibration mode (or bending phenomenon) of d31 displacement.

[0084] The flexible portion 313 shapes the overall shape of the piezoelectric composite layer 310 while imparting flexibility to the piezoelectric composite layer 310. According to an example, the flexible portion 313 is disposed between the plurality of piezoelectric portions 311 and connects to the adjacent piezoelectric portions 311 to shape the piezoelectric composite layer 310 in a polygonal shape. For example, the flexible portion 313 may surround or cover at least three of the four outer surfaces (or side walls) of each of the plurality of piezoelectric portions 311.

[0085] The flexible part 313 has a lower modulus and viscoelasticity than the piezoelectric part 311, and therefore can improve the reliability of the piezoelectric part 311, which is vulnerable to shock due to its brittle characteristics. For example, the flexible vibration module 300 for vibrating the display panel 100 can have the maximum vibration characteristics when it has shock resistance and high rigidity. In order for the flexible vibration module 300 to have shock resistance and high rigidity, the flexible part 313 can be made of a material having a relatively high damping factor (tan δ) and a relatively high stiffness characteristic. For example, the flexible part 313 can be made of a material having a damping factor (tan δ) of 0.1 to 1 [Gpa] and a stiffness characteristic of 0 to 10 [Gpa]. The damping factor (tan δ) and stiffness characteristic can also be explained by the correlation between the loss factor and the modulus. The flexible part 313 can be made of a material having a loss factor of 0.01 to 1 and a modulus of 1 to 10 [Gpa].

[0086] The flexible portion 313 may be made of an organic material or an organic polymer having a flexible characteristic compared to the piezoelectric portion 311. For example, the flexible portion 313 may include an organic material, an organic polymer, an organic piezoelectric material, or an organic non-piezoelectric material. The flexible portion 313 may be expressed as an organic material portion, an adhesive portion, an elastic portion, a bending portion, a damping portion, or the like.

[0087] According to an embodiment, the flexible portion 313 may include at least one of an organic piezoelectric material and an organic non-piezoelectric material, and therefore, the flexible portion 313 may absorb a shock applied to the piezoelectric portion 311, thereby improving the overall durability of the flexible vibration module 300.

[0088] The organic piezoelectric material constituting the flexible portion 313 may be an organic material having electroactive properties, such as at least one of PVDF (Polyvinylidene fluoride), beta-PVDF (β-Polyvinylidene fluoride), PVDF-TrFE (Polyvinylidene-trifluoroethylene), and PVDF-TrFE-CFE (Polyvinylidene-trifluoroethylene-Chloro Fluoro Ethelene).

[0089] The organic non-piezoelectric material constituting the flexible portion 313 may include a curable resin composition and an adhesive containing the same. For example, the organic non-piezoelectric material may include at least one of an epoxy-based polymer, an acrylic-based polymer, and a silicone-based polymer.

[0090] According to an embodiment, the flexible portion 313 may include a plurality of flexible patterns 313a and a flexible dummy pattern 313b.

[0091] Each of the multiple flexible patterns 313a may be configured to fill gap regions between the multiple piezoelectric portions 311 of the piezoelectric composite layer 310. For example, each of the multiple flexible patterns 313a may be arranged between the multiple piezoelectric portions 311 spaced apart at a certain interval or distance along the first direction (X) while being aligned with the second direction (Y). Thus, each of the multiple flexible patterns 313a may be a line pattern having a second width (W2) corresponding to the interval or distance between the multiple piezoelectric portions 311.

[0092] According to an embodiment, each of the flexible patterns 313a may have the same second width (W2) within a range of process error (or tolerance) occurring in a manufacturing process. The second width (W2) of each of the flexible patterns 313a may be the same as or different from the first width (W1) of the piezoelectric unit 311. The size of each of the flexible patterns 313a may be set according to at least one of the vibration characteristics, flexibility, and size of the flexible vibration module 300. For example, in a flexible vibration module 300 or a display device that requires piezoelectric characteristics rather than flexibility, the first width (W1) of the piezoelectric unit 311 may be set larger than the second width (W2) of the flexible pattern 313a.

[0093] In another embodiment, in a flexible vibration module 300 or a display device that requires flexibility rather than piezoelectric properties, the first width (W1) of the piezoelectric part 311 may be configured to be smaller than the second width (W2) of the flexible pattern 313a. Therefore, since the size of the piezoelectric composite layer 310 can be adjusted according to the properties required for the display device, there is an advantage that the design of the piezoelectric composite layer 310 is easy.

[0094] The flexible dummy pattern 313b may be disposed in a dummy region where the piezoelectric parts 311 and the flexible patterns 313a are not disposed in the piezoelectric composite layer 310. The flexible dummy pattern 313b may form the remaining shape of the overall shape of the flexible vibration module 300 excluding the arrangement shape of the piezoelectric parts 311 and the flexible patterns 313a.

[0095] According to an embodiment, the flexible dummy pattern 313b may be configured to fill dummy areas (or areas where no piezoelectric parts are arranged) that occur at corners of each of the first side (S1) and second side (S2) of the piezoelectric composite layer 310 according to the length gradient of each of the plurality of piezoelectric parts 311. The flexible dummy pattern 313b may be connected to one side of each of the plurality of flexible patterns 313a. For example, each of the plurality of flexible patterns 313a may have a finger structure extending from the flexible dummy pattern 313b to between the plurality of piezoelectric parts 311.

[0096] In some embodiments, the piezoelectric composite layer 310 may have a quadrangular shape due to a plurality of piezoelectric parts 311 arranged on the same plane, and a plurality of flexible patterns 313a and flexible dummy patterns 313b. As another example, the piezoelectric composite layer 310 may have a circular, elliptical, triangular, or polygonal shape having five or more sides. For example, the piezoelectric composite layer 310 may have a polygonal shape having five or more sides. The piezoelectric composite layer 310 may be a vibration source (or vibrating body) that is close to a circle, which may improve vibration characteristics.

[0097] In the piezoelectric composite layer 310, the piezoelectric parts 311 and the flexible patterns 313a of the flexible parts 313 are alternately and repeatedly connected to each other, so that the piezoelectric composite layer 310 has a thin film shape. As a result, the piezoelectric composite layer 310 can be bent in accordance with the shape of the display panel 100, and can have a size corresponding to the display panel 100 or a size that allows the display panel 100 to realize set vibration characteristics or acoustic characteristics by vibration.

[0098] The first electrode layer 320 is disposed on a first surface (or rear surface or back surface) of the piezoelectric composite layer 310 and is electrically connected to the first surface of each of the piezoelectric portions 311. According to an example, the first electrode layer 320 may be made of a transparent conductive material, a semi-transparent conductive material, or an opaque conductive material. For example, the transparent or semi-transparent conductive material may include indium tin oxide (ITO) or indium zinc oxide (IZO). The opaque conductive material may include aluminum (Al), copper (Cu), gold (Au), silver (Ag), molybdenum (Mo), magnesium (Mg), or the like, or may be made of an alloy thereof.

[0099] The second electrode layer 330 is disposed on a second surface (or front surface) opposite to the first surface of the piezoelectric composite layer 310, and is electrically connected to the second surface of each of the piezoelectric portions 311. According to an example, the second electrode layer 330 may be made of a transparent conductive material, a semi-transparent conductive material, or an opaque conductive material. For example, the second electrode layer 330 may be made of the same material as the first electrode layer 320.

[0100] The piezoelectric composite layer 310 may be polarized by a constant voltage applied to the first electrode layer 320 and the second electrode layer 330 in a constant temperature atmosphere or a temperature atmosphere that changes from high temperature to room temperature. The polarization direction of each of the plurality of piezoelectric parts 311 may be determined (or adjusted) by the voltage applied to the first electrode layer 320 and the second electrode layer 330.

[0101] The flexible vibration module 300 according to the first embodiment of the present disclosure may further include a first protective film 340 and a second protective film 350 .

[0102] The first protective film 340 may be disposed to cover the first electrode layer 320 to protect the first surface of the piezoelectric composite layer 310 or the first electrode layer 320. For example, the first protective film 340 may be a PI (polyimide) film or a PET (polyethyleneterephthalate) film.

[0103] The second protective film 350 may be disposed to cover the second electrode layer 330 to protect the second surface of the piezoelectric composite layer 310 or the second electrode layer 330. For example, the second protective film 350 may be a PI (polyimide) film or a PET (polyethyleneterephthalate) film.

[0104] In another example, the arrangement structure of the piezoelectric part 311 in the flexible vibration module 300 is not limited to the arrangement structure shown in FIG. 3. The arrangement structure can be changed to various structures depending on at least one of the vibration characteristics, flexibility, and size of the flexible vibration module 300. For example, the length gradient or vibration frequency of the piezoelectric part 311 can be set (or adjusted) to vary randomly, rather than being set (or adjusted) to gradually increase from both ends (EP1, EP2) of the piezoelectric composite layer 310 to the first center (CP1). As another example, the length gradient or vibration frequency of the piezoelectric part 311 can be set (or adjusted) to gradually increase from one end (EP1) of the piezoelectric composite layer 310 to the other end (EP2).

[0105] The flexible vibration module 300 according to the first embodiment of the present specification may provide audio or tactile feedback to a user by vibrating the display panel 100 by a bending phenomenon caused by an inverse piezoelectric effect according to an applied signal in each of the piezoelectric parts 311. Since the flexible parts 313 filled or disposed between the piezoelectric parts 311 have flexibility, even if the piezoelectric composite layer 310 is bent by a bending phenomenon, the piezoelectric parts 311 may not be damaged or their performance may not be deteriorated.

[0106] The flexible vibration module 300 according to the first embodiment of the present specification is disposed on the rear surface of the display panel 100 and can sufficiently vibrate the display panel 100 in the up-down (or front-back) direction, so that necessary sound can be output to the front of the display device. The piezoelectric part 311 and the flexible part 313 can implement a piezoelectric composite layer 310 implemented in a pattern shape. Therefore, the piezoelectric composite layer 310 can have a size corresponding to the display panel 100, so that the panel coverage (or contact area) with the display panel 100 is increased, and the acoustic characteristics due to the vibration of the display panel 100 can be improved. For example, the flexible vibration module 300 can have a large area equivalent to the size of the display panel 100. Therefore, it is possible to improve the sound pressure characteristics in the low frequency range, which is a drawback of the film type piezoelectric body, and to reduce the driving voltage. The flexible vibration module 300 according to the first embodiment of the present specification can be implemented in a thin film form. Therefore, the flexible vibration module 300 can be integrated or mounted on the display device without being interfered with by other parts and / or mechanisms constituting the display device.

[0107] The flexible vibration module 300 according to the first embodiment of the present specification can have various vibration frequencies according to the magnitude gradient of each of the plurality of piezoelectric units 311. Therefore, the flexible vibration module 300 can vibrate the display panel through vibrations having various vibration frequencies according to an electric field caused by a signal applied to each of the plurality of piezoelectric units 311. Therefore, it is possible to improve the sound pressure characteristics and sound pressure flattening (or flatness) characteristics of the sound generated by the vibration of the display panel 100 and expand the sound reproduction band.

[0108] FIG. 5 is a diagram showing a flexible vibration module according to a second embodiment of the present specification, in which the arrangement structure of the piezoelectric parts in the piezoelectric composite layer shown in FIG. 3 is modified.

[0109] Referring to FIG. 5, a piezoelectric composite layer 310 may include a plurality of piezoelectric portions 311 and a flexible portion 313 disposed between the plurality of piezoelectric portions 311 .

[0110] Each of the plurality of piezoelectric parts 311 may have a symmetrical structure with respect to the first middle part (CP1) of the piezoelectric composite layer 310 along the first direction (X). According to an example, each of the plurality of piezoelectric parts 311 may have a size that gradually decreases from both ends (EP1, EP2) of the piezoelectric composite layer 310 to the first middle part (CP1) along the first direction (X), and may have various vibration frequencies corresponding to various sizes (or length gradients). However, each of the plurality of piezoelectric parts 311 may gradually decrease from both ends (EP1, EP2) of the piezoelectric composite layer 310 to the first middle part (CP1).

[0111] The flexible portion 313 can shape the overall shape of the piezoelectric composite layer 310 while imparting flexibility to the piezoelectric composite layer 310. According to an embodiment, the flexible portion 313 can be disposed between the piezoelectric portions 311 and connected to the adjacent piezoelectric portions 311 to shape the piezoelectric composite layer 310 in a polygonal shape. For example, the flexible portion 313 can surround or cover three or four outer surfaces (or side walls) of each of the piezoelectric portions 311. The flexible portion 313 includes a plurality of flexible patterns 313a configured to fill gap regions between the piezoelectric portions 311, and a flexible dummy pattern 313b disposed in a dummy region where the piezoelectric portions 311 and the flexible patterns 313a are not disposed, which is similar to the arrangement position of the flexible portion shown in FIG. 3 and FIG. 4.

[0112] The flexible vibration module 300 according to the second embodiment of the present specification can vibrate the display panel at various vibration frequencies according to the magnitude gradient of each of the piezoelectric parts 311. Therefore, the sound pressure characteristic and the sound pressure flattening (or flatness) characteristic of the sound generated by the vibration of the display panel 100 can be improved, and the sound reproduction band can be expanded. For example, the flexible vibration module 300 according to the second embodiment of the present specification can be arranged so that the piezoelectric parts 311 having a relatively low vibration frequency (or low resonance frequency) are adjacent to both ends (EP1, EP2) due to their relatively large size. Therefore, the vibration area of ​​the display panel 100 vibrating due to the piezoelectric parts 311 can be expanded, and thus the sound in the low frequency band can be improved. The vibration area (or area) generating rich low sound can be utilized as widely as possible.

[0113] FIG. 6 is a diagram showing a flexible vibration module according to a third embodiment of the present specification, in which the arrangement structure of the piezoelectric parts in the piezoelectric composite layer shown in FIG. 3 is modified.

[0114] Referring to FIG. 6 , in a flexible vibration module 300 according to a third embodiment of the present specification, a piezoelectric composite layer 310 may include a plurality of piezoelectric portions 311 and a flexible portion 313 disposed between the plurality of piezoelectric portions 311.

[0115] Each of the plurality of piezoelectric portions 311 has a size that gradually increases from both ends (EP1, EP2) of the piezoelectric composite layer 310 to the first middle portion (CP1) along the first direction (X), and can have various vibration frequencies corresponding to the various sizes.

[0116] The center of each of the plurality of piezoelectric parts 311 in the length direction in the second direction (Y) may be disposed in the second middle part (CP2) of the piezoelectric composite layer 310. The ends of the remaining piezoelectric parts of the plurality of piezoelectric parts 311, except for the piezoelectric parts disposed in the first middle part (CP1) of the piezoelectric composite layer 310, may be spaced apart from both sides (or upper and lower sides) of the piezoelectric composite layer 310 in the first direction (X). Each of the plurality of piezoelectric parts 311 has a size that gradually increases from both ends (EP1, EP2) of the piezoelectric composite layer 310 to the first middle part (CP1) along the first direction (X), and thus may have various vibration frequencies corresponding to various sizes (or length gradients). In this way, each of the plurality of piezoelectric parts 311 is the same as that of FIGS. 3 and 4, except that it is disposed in a left-right symmetrical structure with respect to the first middle part (CP1) of the piezoelectric composite layer 310 and disposed in a top-bottom symmetrical structure with respect to the second middle part (CP2) of the piezoelectric composite layer 310.

[0117] The flexible portion 313 can shape the overall shape of the piezoelectric composite layer 310 while imparting flexibility to the piezoelectric composite layer 310. According to an example, the flexible portion 313 can be disposed between the piezoelectric portions 311 and connected to the adjacent piezoelectric portions 311 to shape the piezoelectric composite layer 310 in a polygonal shape. For example, the flexible portion 313 can surround or cover all four outer surfaces (or side walls) of each of the piezoelectric portions 311. The flexible portion 313 includes a plurality of flexible patterns 313a configured to fill gap regions between the piezoelectric portions 311, and a flexible dummy pattern 313b disposed in a dummy region where the piezoelectric portions 311 and the flexible patterns 313a are not disposed, which is similar to the flexible portion arrangement shown in FIG. 3 and FIG. 4 except for the arrangement position of the flexible portion.

[0118] In the flexible vibration module 300 according to this embodiment, each of the plurality of piezoelectric parts 311 may have a size that gradually decreases from both ends (EP1, EP2) of the piezoelectric composite layer 310 to the first middle part (CP1) along the first direction (X).

[0119] In the flexible vibration module 300 according to the third embodiment, the arrangement structure of the piezoelectric part 311 is not limited to the arrangement structure shown in Fig. 6. In this embodiment, the flexible vibration module 300 can be changed to various structures depending on at least one of the vibration characteristics, flexibility, and size of the flexible vibration module 300. For example, the length gradient or vibration frequency of the piezoelectric part 311 can be set (or adjusted) to vary randomly rather than gradually increasing from both ends (EP1, EP2) of the piezoelectric composite layer 310 to the first center (CP1), or can be set (or adjusted) to increase gradually or vary randomly from one end (EP1) of the piezoelectric composite layer 310 to the other end (EP2).

[0120] FIG. 7 is a diagram showing a flexible vibration module according to a fourth embodiment of the present specification, and FIG. 8 is a cross-sectional view of line III-III' shown in FIG. 7, which is a modified structure of the piezoelectric composite layer shown in FIG. 3.

[0121] Referring to Figures 7 and 8, in a flexible vibration module 300 according to the fourth embodiment of the present specification, a piezoelectric composite layer 310 may include a plurality of piezoelectric portions 311 and a flexible portion 313 arranged between the plurality of piezoelectric portions 311.

[0122] Each of the piezoelectric parts 311 may include a polygonal pattern. For example, each of the piezoelectric parts 311 may be a line pattern having a first length (L1), spaced apart from each other along a first direction (X) and arranged side by side in a second direction (Y).

[0123] Some of the plurality of piezoelectric parts 311 may have different sizes. The size of the piezoelectric parts 311 may be any one of length, width, thickness, area, surface area, and volume. For example, some of the plurality of piezoelectric parts 311 may have the same size within a range of process error (or tolerance) occurring in a manufacturing process, and the rest may have different sizes.

[0124] Each of the plurality of piezoelectric parts 311 may have a bilaterally symmetrical structure with respect to a first middle part (CP1) of the piezoelectric composite layer 310, and may have a vertically symmetrical structure with respect to a second middle part (CP2) of the piezoelectric composite layer 310. According to an example, each of the plurality of piezoelectric parts 311 may have a size that gradually increases from both ends (EP1, EP2) of the piezoelectric composite layer 310 to the first middle part (CP1) along the first direction (X), and thus may have various vibration frequencies corresponding to various sizes (or width gradients).

[0125] Each of the piezoelectric parts 311 according to this embodiment may vibrate in a vibration mode with a displacement (or direction) of d32. The vibration frequency and the resonant frequency of the piezoelectric part 311 may increase as the width decreases along the first direction (X).

[0126] The piezoelectric composite layer 310 according to one embodiment may include 1st to Nth (N is an odd number equal to or greater than 5) piezoelectric portions (311[1] to 311[N]), in which the i+1th (i is (N-1) / 2) piezoelectric portion (311[i+1]) is disposed in a first intermediate portion (CP1) of the piezoelectric composite layer 310, and the 1st to i-th piezoelectric portions (311[1] to 311[i]) may be disposed on a first side surface (S1) between one end (EP1) of the piezoelectric composite layer 310 and the first intermediate portion (CP1). The i+2th to Nth piezoelectric portions (311[i+2] to 311[N]) may be disposed on a second side surface (S2) between the other end (EP2) of the piezoelectric composite layer 310 and the first intermediate portion (CP1).

[0127] According to an embodiment, each of the first to Nth piezoelectric portions (311[1] to 311[N]) may have the same length (L1) and thickness (H1) (or height) within the range of process error (or tolerance) occurring in the manufacturing process. The i+1th piezoelectric portion (311[i+1]) may have the widest width (W3) among the piezoelectric portions 311. The first piezoelectric portion (311[1]) and the Nth piezoelectric portion (311[N]) may be disposed closest to the end of the piezoelectric composite layer 310 and may have the narrowest width (W4) among the piezoelectric portions 311. The second to ith piezoelectric portions (311[2] to 311[i]) may have different widths within a range wider than the first piezoelectric portion (311[1]) and narrower than the i+1th piezoelectric portion (311[i+1]), and may have a wider width closer to the i+1th piezoelectric portion (311[i+1]). The i+2 to N-1 piezoelectric parts (311[i+2] to 311[N-1]) can have different widths within a range that is wider than the N piezoelectric part (311[N]) and narrower than the i+1 piezoelectric part (311[i+1]), and the closer to the i+1 piezoelectric part (311[i+1]), the wider the width. Therefore, the 1st to i+1st piezoelectric parts (311[1] to 311[i+1]) can have different vibration frequencies due to their different widths, and the i+2 to Nth piezoelectric parts (311[i+2] to 311[N]) can have different vibration frequencies due to their different widths. The piezoelectric parts that have a symmetrical structure with respect to the i+1 piezoelectric part (311[i+1]) among the 1st to Nth piezoelectric parts (311[1] to 311[N]) can have the same vibration frequency.

[0128] According to an embodiment, the plurality of piezoelectric units 311 may be grouped into a plurality of groups (or piezoelectric groups). The plurality of groups may include the same or different numbers of piezoelectric units 311. The piezoelectric units arranged in each group may have the same size within a range of process error (or tolerance) occurring in a manufacturing process. Each of the plurality of piezoelectric units 311 may have a different size for each group. For example, each of the plurality of piezoelectric units 311 may have the same length and thickness (or height) within a range of process error (or tolerance) occurring in a manufacturing process, and may have a different width for each group. Thus, each of the plurality of groups may have a different vibration frequency.

[0129] According to an embodiment, each of the plurality of groups may include two or more piezoelectric parts 311 from among the plurality of piezoelectric parts 311, and the two or more piezoelectric parts 311 included in each group may be disposed adjacent to each other or may be disposed in a symmetrical structure with respect to the first middle part (CP1) of the piezoelectric composite layer 310. As an embodiment, as shown in FIG. 7, when the piezoelectric composite layer 310 includes first to seventeenth piezoelectric parts (311[1] to 311[N]), the seventeen piezoelectric parts (311[1] to 311[N]) may be grouped into first to ninth groups. The first group may include one piezoelectric part (311[i+1]) disposed in the first middle part (CP1) of the piezoelectric composite layer 310, and each of the second to ninth groups may include two piezoelectric parts, and the two piezoelectric parts included in each of the second to ninth groups may be disposed in a symmetrical structure with respect to the first middle part (CP1) of the piezoelectric composite layer 310. For example, the first group may include a ninth piezoelectric portion (311[i+1]) having the widest width (W3) and disposed at the first middle portion (CP1) of the piezoelectric composite layer 310, the second group may include an eighth piezoelectric portion (311[i]) and a tenth piezoelectric portion (311[i+2]) closest to the first group, and the ninth group may include a first piezoelectric portion (311[1]) having the narrowest width (W4) and closest to one end (EP1) of the piezoelectric composite layer 310 and a seventeenth piezoelectric portion (311[N]) closest to the other end (EP2) of the piezoelectric composite layer 310. Thus, the first to ninth groups may have different frequencies due to the piezoelectric portions 311 having different widths for each group, and the frequencies for each group may be symmetrical about the first middle portion (CP1) of the piezoelectric composite layer 310.

[0130] The flexible portion 313 may include a plurality of flexible patterns 313a arranged between the plurality of piezoelectric portions 311. Each of the plurality of flexible patterns 313a is arranged between the plurality of piezoelectric portions 311 to complement the impact resistance of the piezoelectric portion 311 and to impart flexibility to the flexible vibration module 300.

[0131] The multiple flexible patterns 313a and the multiple piezoelectric portions 311 may be arranged (or arrayed) alternately and repeatedly on the same plane (or the same layer). Each of the multiple flexible patterns 313a is configured to fill the gap between two adjacent piezoelectric portions 311, thereby being able to connect or bond to the adjacent piezoelectric portions 311. For example, each of the multiple flexible patterns 313a may be a line pattern having a width (W5) corresponding to the gap between two adjacent piezoelectric portions 311.

[0132] Each of the flexible patterns 313a may have the same size, for example, width, area, or volume, within the range of process error (or tolerance) occurring in the manufacturing process, but is not limited thereto, and may have different sizes from each other or may have a size corresponding to the size of two adjacent piezoelectric parts 311. Thus, the size of each of the flexible patterns 313a may be set according to at least one condition of the vibration characteristics, flexibility, and size of the flexible vibration module 300. For example, in a flexible vibration module 300 or a display device that requires piezoelectric characteristics more than flexibility, the width (W5) of the flexible pattern 313a may be relatively reduced. As another embodiment, in a flexible vibration module 300 or a display device that requires flexibility more than piezoelectric characteristics, the width (W5) of the flexible pattern 313a may be relatively increased. Therefore, since the size of the piezoelectric composite layer 310 can be adjusted according to the characteristics required for the display device, there is an advantage that the design of the piezoelectric composite layer 310 is easy.

[0133] Alternatively, in the flexible vibration module 300 according to the fourth embodiment of the present specification, each of the plurality of piezoelectric parts 311 may have a bilaterally symmetrical structure with respect to a first middle part (CP1) of the piezoelectric composite layer 310 and a vertically symmetrical structure with respect to a second middle part (CP2) of the piezoelectric composite layer 310, and may have a size that gradually decreases from both ends (EP1, EP2) of the piezoelectric composite layer 310 to the first middle part (CP1) along the first direction (X). Therefore, the plurality of piezoelectric parts 311 may have various vibration frequencies corresponding to various sizes (or width gradients).

[0134] 7, the layout structure of the piezoelectric part 311 in the flexible vibration module 300 according to the fourth embodiment may be changed to various structures according to at least one required condition of the vibration characteristics, flexibility, and size of the flexible vibration module 300. As an example, the width gradient or vibration frequency of the piezoelectric part 311 may be set (or adjusted) to vary or change randomly rather than being set (or adjusted) to gradually increase from both ends (EP1, EP2) of the piezoelectric composite layer 310 to the first center (CP1), or may be set (or adjusted) to gradually increase or change randomly from one end (EP1) of the piezoelectric composite layer 310 to the other end (EP2).

[0135] FIG. 9 shows a flexible vibration module according to a fifth example of the present specification, and FIG. 10 is a cross-sectional view of line IV-IV' shown in FIG. 9, which is a modified version of the piezoelectric composite layer structure shown in FIG. 3.

[0136] Referring to Figures 9 and 10, in a flexible vibration module 300 according to the fifth embodiment of the present specification, a piezoelectric composite layer 310 may include a plurality of piezoelectric parts 311 and a flexible part 313 arranged between the plurality of piezoelectric parts 311.

[0137] Each of the plurality of piezoelectric parts 311 may include a polygonal pattern. For example, each of the plurality of piezoelectric parts 311 may be a line pattern having a predetermined length, spaced apart from each other along a first direction (X) and arranged parallel to a second direction (Y).

[0138] Each of the piezoelectric parts 311 may have the same size within the range of process error (or tolerance) that occurs in the manufacturing process. For example, each of the piezoelectric parts 311 may have the same width (W6), thickness, and length. The size of each of the piezoelectric parts 311 may be symmetrical with respect to a first middle part (CP1) (or a center line in the lateral direction) of the piezoelectric composite layer 310 along the first direction (X).

[0139] Each of the plurality of piezoelectric portions 311 can include a lower piezoelectric portion 311a and an upper piezoelectric portion 311b.

[0140] The thicknesses (or heights) of the lower piezoelectric portion 311a and the upper piezoelectric portion 311b of each of the plurality of piezoelectric portions 311 may all be different. The thicknesses (or heights) of the lower piezoelectric portion 311a and the upper piezoelectric portion 311b may all have different thickness ratios (or thickness gradients) for each piezoelectric portion 311. Such thickness ratios may be symmetrical with respect to the first middle portion (CP1) of the piezoelectric composite layer 310. For example, the lower piezoelectric portion 311a and the upper piezoelectric portion 311b constituting each of the plurality of piezoelectric portions 311 may have asymmetric thicknesses with respect to the middle thickness (or middle height) of the piezoelectric portion 311.

[0141] As another example, some of the piezoelectric parts 311 may include lower piezoelectric parts 311a and upper piezoelectric parts 311b having the same thickness (or height), and all the rest may include lower piezoelectric parts 311a and upper piezoelectric parts 311b having different thicknesses (or heights). For example, based on the first direction (X), any one of the voltage parts (311[#5]) arranged between one end (EP1) and the first middle part (CP1) of the piezoelectric composite layer 310 may include lower piezoelectric parts 311a and upper piezoelectric parts 311b having the same thickness (or height). Any one of the piezoelectric parts (311[#13]) arranged between the other end (EP2) and the first middle part (CP1) of the piezoelectric composite layer 310 may include lower piezoelectric parts 311a and upper piezoelectric parts 311b having the same thickness (or height). Each of the remaining piezoelectric portions, except for the piezoelectric portions (311[#5], 311[#12]) in which the lower piezoelectric portion 311a and the upper piezoelectric portion 311b have the same thickness (or height), may include a lower piezoelectric portion 311a and an upper piezoelectric portion 311b each having a different thickness (or height).

[0142] Each lower piezoelectric portion 311a of the plurality of piezoelectric portions 311 may have a thickness that is a portion of the overall thickness of the piezoelectric portion 311. At least one of the plurality of lower piezoelectric portions 311a may have a different thickness. As an example, some of the plurality of lower piezoelectric portions 311a may have the same thickness within a range of process error (or tolerance) occurring in a manufacturing process, and the rest may have different thicknesses. As another example, the plurality of lower piezoelectric portions 311a may have different thicknesses.

[0143] Each of the lower piezoelectric parts 311a may have a symmetrical structure with respect to the first middle part (CP1) of the piezoelectric composite layer 310. For example, each of the lower piezoelectric parts 311a may be arranged in a stepped shape between each of both ends (EP1, EP2) of the piezoelectric composite layer 310 and the first middle part (CP1). Each of the lower piezoelectric parts 311a may have a thickness that gradually decreases from both ends (EP1, EP2) of the piezoelectric composite layer 310 to the first middle part (CP1) along the first direction (X). Therefore, the lower piezoelectric parts 311a may have various vibration frequencies corresponding to various magnitudes (or thickness gradients) or may have different vibration frequencies.

[0144] At least two of the upper piezoelectric portions 311b of each of the multiple piezoelectric portions 311 can have different vibration frequencies. For example, the upper piezoelectric portions 311b of each of the multiple piezoelectric portions 311 can have different vibration frequencies.

[0145] The upper piezoelectric portion 311b of each of the plurality of piezoelectric portions 311 may have a thickness that is the remaining thickness obtained by subtracting the thickness of the overlapping lower piezoelectric layer 311a from the total thickness of the piezoelectric portion 311. The remaining piezoelectric portions, except for the piezoelectric portion disposed in the first middle portion (CP1) of the piezoelectric composite layer 310, may have an asymmetric thickness structure based on the middle thickness (or middle height) of the piezoelectric portion 311. For example, each of the plurality of upper piezoelectric portions 311b may be disposed in a stepped shape between each of both ends (EP1, EP2) of the piezoelectric composite layer 310 and the first middle portion (CP1). Each of the plurality of upper piezoelectric portions 311b may have a thickness that gradually increases from both ends (EP1, EP2) of the piezoelectric composite layer 310 to the first middle portion (CP1) along the first direction (X), thereby having various vibration frequencies corresponding to various magnitudes (or thickness gradients).

[0146] Each of the remaining piezoelectric portions, except for the piezoelectric portions (311[#5], 311[#13]) having the same thickness (or height) as the lower piezoelectric portion 311a and the upper piezoelectric portion 311b, may have a vertically laminated structure. The vertically laminated structure may include the lower piezoelectric portion 311a having a relatively large thickness and the upper piezoelectric portion 311b having a relatively small thickness depending on the arrangement position between both ends (EP1, EP2) and the first middle portion (CP1) of the piezoelectric composite layer 310. Alternatively, the vertically laminated structure may include the lower piezoelectric portion 311a having a relatively small thickness and the upper piezoelectric portion 311b having a relatively large thickness depending on the arrangement position between both ends (EP1, EP2) and the first middle portion (CP1) of the piezoelectric composite layer 310.

[0147] Each of the lower piezoelectric parts 311a and each of the upper piezoelectric parts 311b according to this embodiment can vibrate in a vibration mode with a displacement (or direction) of d33. The vibration frequency and the resonant frequency of the piezoelectric part 311 can increase as the thickness (or height) decreases along the third direction (Z) (or thickness direction).

[0148] According to an embodiment, each of the plurality of piezoelectric units 311 may be grouped into a plurality of groups (or piezoelectric groups). Each of the plurality of groups may include the same or different number of piezoelectric units 311. For example, the lower piezoelectric unit 311a and the upper piezoelectric unit 311b of each of the plurality of piezoelectric units 311 may all have the same length and width within a range of process error (or tolerance) occurring in a manufacturing process, and may have different thicknesses for each group. Thus, each of the plurality of groups may have a different vibration frequency.

[0149] According to an embodiment, each of the plurality of groups may include two or more piezoelectric parts 311 from among the plurality of piezoelectric parts 311. The two or more piezoelectric parts 311 included in each group may be disposed adjacent to each other or may be disposed in a bilaterally symmetrical structure based on a first middle portion (CP1) of the piezoelectric composite layer 310. For example, as shown in Figs. 9 and 10, when the piezoelectric composite layer 310 includes first to seventeenth piezoelectric parts 311, the seventeen piezoelectric parts 311 may be grouped into first to ninth groups.

[0150] The first group may include one piezoelectric portion (311[#9]) disposed in the first middle portion (CP1) of the piezoelectric composite layer 310. Each of the second to ninth groups may include two piezoelectric portions, and the two piezoelectric portions included in each of the second to ninth groups may be disposed in a symmetrical structure with respect to the first middle portion (CP1) of the piezoelectric composite layer 310. For example, the first group may include a ninth piezoelectric portion (311[#9]) having a lower piezoelectric portion 311a and an upper piezoelectric portion 311b having different thicknesses and disposed in the first middle portion (CP1) of the piezoelectric composite layer 310. The second group may include an eighth piezoelectric portion and a tenth piezoelectric portion closest to the first group, and the ninth group may include a first piezoelectric portion closest to one end (EP1) of the piezoelectric composite layer 310 and a seventeenth piezoelectric portion closest to the other end (EP2) of the piezoelectric composite layer 310. The piezoelectric portions (311[#5]-311[#13]) included in some of the second to ninth groups may include lower piezoelectric portions 311a and upper piezoelectric portions 311b having the same thickness. The piezoelectric portions included in each of the remaining groups may include lower piezoelectric portions 311a and upper piezoelectric portions 311b having different thicknesses for each group depending on the arrangement position. Therefore, each of the first to ninth groups may have different vibration frequencies due to the piezoelectric portions 311 including the lower piezoelectric portions 311a and upper piezoelectric portions 311b having different thicknesses for each group, and the vibration frequencies of each group may be symmetrical about the first middle portion (CP1) of the piezoelectric composite layer 310.

[0151] The flexible portions 313 are disposed between the piezoelectric portions 311 to complement the impact resistance of the piezoelectric portions 311 and to impart flexibility to the flexible vibration module 300 .

[0152] The flexible portion 313 and each of the plurality of piezoelectric portions 311 may be arranged (or arrayed) alternately and repeatedly on the same plane (or the same layer). The flexible portion 313 is configured to fill the gap between two adjacent piezoelectric portions 311, thereby being able to connect or bond the adjacent piezoelectric portions 311. For example, the flexible portion 313 may be a line pattern having a width (W6) corresponding to the gap between two adjacent piezoelectric portions 311.

[0153] In one embodiment, each of the flexible parts 313 disposed between the piezoelectric parts 311 may have the same size, for example, width, area, or volume, within the range of process error (or allowable error) occurring in the manufacturing process, but is not necessarily limited thereto, and may have different sizes or may have a size corresponding to the size of two adjacent piezoelectric parts 311. Thus, the size of each flexible part 313 may be set according to at least one condition of the vibration characteristics, flexibility, and size of the flexible vibration module 300. For example, in a flexible vibration module 300 or a display device that requires piezoelectric characteristics more than flexibility, the width (W6) of the piezoelectric part 311 may be set larger than the width (W7) of the flexible part 313. As another example, in a flexible vibration module 300 or a display device that requires flexibility more than piezoelectric characteristics, the width (W6) of the piezoelectric part 311 may be configured smaller than the width (W7) of the flexible part 313. Therefore, since the size of the piezoelectric composite layer 310 can be adjusted according to the characteristics required for the display device, there is an advantage that the design of the piezoelectric composite layer 310 is easy.

[0154] The flexible portion 313 according to this embodiment may include a lower flexible portion 313a and an upper flexible portion 313b.

[0155] The lower flexible portion 313a may be disposed between the lower piezoelectric portions 311a of the plurality of piezoelectric portions 311. The lower flexible portion 313a and the lower piezoelectric portions 311a may be disposed (or arranged) alternately and repeatedly on the same plane (or the same layer). The lower flexible portion 313a may be configured to fill the gap between two adjacent lower piezoelectric portions 311a, thereby connecting or bonding the adjacent lower piezoelectric portions 311a. As a result, the lower flexible portion 313a may have the same thickness as the adjacent lower piezoelectric portion 311a. Such a lower flexible portion 313a and the respective lower piezoelectric portions 311a of the plurality of piezoelectric portions 311 may constitute the lower piezoelectric composite layer 310a of the piezoelectric composite layer 310.

[0156] The upper flexible portion 313b may be disposed between the upper piezoelectric portions 311b of the plurality of piezoelectric portions 311. The upper flexible portion 313b and the upper piezoelectric portions 311b may be disposed (or arranged) alternately and repeatedly on the same plane (or the same layer). The upper flexible portion 313b may be configured to fill the gap between two adjacent upper piezoelectric portions 311b, thereby connecting or adhering to the adjacent upper piezoelectric portions 311b. As a result, the upper flexible portion 313b may have the same thickness as the adjacent upper piezoelectric portion 311b. Such upper flexible portion 313b and the upper piezoelectric portion 311b of each of the plurality of piezoelectric portions 311 may constitute the upper piezoelectric composite layer 310b of the piezoelectric composite layer 310.

[0157] In the piezoelectric composite layer 310 according to this embodiment, each of the plurality of piezoelectric parts 311 may have a vertically laminated structure in which the lower piezoelectric part 311a and the upper piezoelectric part 311b are laminated together. Therefore, the expansion force (tensile force) and contraction force (or compression force) due to the bimorph structure are further increased, thereby improving the sound pressure characteristics.

[0158] The piezoelectric composite layer 310 according to this embodiment may further include a first opposing electrode layer 360, a second opposing electrode layer 370, and an insulating layer 380.

[0159] The first counter electrode layer 360 may be electrically connected to the lower piezoelectric portion 311a of each of the plurality of piezoelectric portions 311. For example, the first counter electrode layer 360 may be disposed on the lower piezoelectric composite layer 310a of the piezoelectric composite layer 310 and electrically connected to the lower piezoelectric portion 311a of each of the plurality of piezoelectric portions 311. The first counter electrode layer 360 may be made of the same material as the first electrode layer 320. In this manner, the lower piezoelectric portion 311a of each of the plurality of piezoelectric portions 311 may vibrate in response to an electrical signal applied to the first electrode layer 320 and the first counter electrode layer 360.

[0160] The second opposing electrode layer 370 may be embodied to be electrically connected to a first surface (rear surface) of the upper piezoelectric portion 311b of each of the plurality of piezoelectric portions 311. For example, the second opposing electrode layer 370 may be disposed on a rear surface of the upper piezoelectric composite layer 310b of the piezoelectric composite layer 310 and electrically connected to each of the upper piezoelectric portions 311b of the plurality of piezoelectric portions 311. The second opposing electrode layer 370 may be made of the same material as the second electrode layer 330, but is not limited thereto. The upper piezoelectric portion 311b of each of the plurality of piezoelectric portions 311 may vibrate in response to an electrical signal applied to the second electrode layer 330 and the second opposing electrode layer 370.

[0161] The insulating layer 380 can electrically insulate the first opposing electrode layer 360 and the second opposing electrode layer 370 by being interposed between them. The insulating layer 380 can include an electrically insulating material that is compressible and resilient while having adhesive properties. For example, the insulating layer 380 can include at least one of an epoxy-based polymer, an acrylic-based polymer, and a silicone-based polymer.

[0162] As another embodiment, in the flexible vibration module 300 according to this embodiment, each of the insulating layer 380 and the second opposing electrode layer 370 may be omitted. As an embodiment, as shown in FIG. 11, the first opposing electrode layer 360 may be electrically connected to the second surface (or front surface) of each of the lower piezoelectric portions 311a arranged in the lower piezoelectric composite layer 310a and at the same time to the first surface (or back surface) of each of the upper piezoelectric portions 311b arranged in the upper piezoelectric composite layer 310b. Thus, the first opposing electrode layer 360 may be used as a common electrode (or shared electrode) of the lower piezoelectric composite layer 310a and the upper piezoelectric composite layer 310b, and in this case, the polarization direction of the lower piezoelectric portion 311a in each of the multiple piezoelectric portions 311 may be opposite to the polarization direction of the upper piezoelectric portion 311b.

[0163] 9, the arrangement structure of the piezoelectric unit 311 in the flexible vibration module 300 according to the fifth embodiment may be changed to various structures depending on at least one of the vibration characteristics, flexibility, and size of the flexible vibration module 300. For example, the thickness gradient or frequency of the lower piezoelectric unit 311a included in each piezoelectric unit 311 may be set (or adjusted) to vary randomly rather than gradually decreasing from both ends (EP1, EP2) of the piezoelectric composite layer 310 to the first center (CP1), or may be set (or adjusted) to vary randomly or gradually decrease from one end (EP1) of the piezoelectric composite layer 310 to the other end (EP2).

[0164] In the flexible vibration module 300 according to the fifth embodiment of the present specification, each of the piezoelectric parts 311 can have various vibration frequencies due to the thickness gradient of the lower piezoelectric part 311a and the upper piezoelectric part 311b having a vertically laminated structure. Therefore, the piezoelectric parts 311 can vibrate the display panel through vibrations having various vibration frequencies according to an electric field caused by a signal applied to each of the piezoelectric parts 311. Therefore, the sound pressure characteristic and sound pressure flattening (or flatness) characteristic of the sound generated by the vibration of the display panel 100 can be increased, and the reproduction band of the sound range can be expanded. The flexible vibration module 300 according to the fifth embodiment of the present specification can sufficiently vibrate the display panel in the up and down (or front and back) directions by further increasing the expansion force (tensile force) and contraction force (or compression force) due to the bimorph structure of the piezoelectric composite layer 310. As a result, the sound pressure characteristic and sound pressure flattening characteristic of the sound generated by the vibration of the display panel 100 can be further increased, and the reproduction band of the sound range can be further expanded.

[0165] The flexible vibration module 300 according to the first to fifth embodiments of the present specification may be applied to a display device using a display panel as a diaphragm by having a thin film shape having relatively high flexibility. For example, the flexible vibration module 300 according to the embodiments of the present specification may be applied to a flexible display device, for example, a curved display apparatus curved with a predetermined radius of curvature. Without being limited thereto, the flexible vibration module 300 may be applied to a rollable display apparatus that is wound or unwound in a spiral shape, a bendable display apparatus, a wearable display apparatus that is worn around the wrist, or a commercial display having a plurality of curved portions. For example, the flexible vibration module 300 may be curved in response to a predetermined radius of curvature or in response to being wound or unwound in a spiral shape, so that it corresponds to the entire display area of ​​the display panel, may be arranged on the display panel so as to overlap, or may be arranged on the display panel so as to have a preset interval.

[0166] Figure 12 is another cross-sectional view of line I-I' shown in Figure 1, and Figure 13 is a diagram showing the flexible vibration module and partition shown in Figure 12, which is a modified version of the flexible vibration module in the display device shown in Figures 1 and 2.

[0167] 12 and 13, in a display device according to another embodiment of the present specification, the flexible vibration module 300 may include a first flexible vibration module 300-1 and a second flexible vibration module 300-2 arranged on the rear surface of the display panel 100.

[0168] The rear surface (or back surface or underside) of the display panel 100 may include a first and a second region (A1, A2). For example, the rear surface (or back surface or underside) of the display panel 100 may be divided into the first and the second region (A1, A2). For example, on the rear surface of the display panel 100, the first region (A1) may be the left region, and the second region (A2) may be the right region. The first and the second regions (A1, A2) may be symmetrical with respect to the middle line (CL) of the display panel 100 with respect to the first direction (X).

[0169] The first flexible vibration module 300-1 may be disposed in the first area (A1) of the display panel 100. The first flexible vibration module 300-1 may vibrate the first area (A1) of the display panel 100 to generate a vibration sound of the first panel or generate a first haptic feedback in the first area (A1) of the display panel 100. For example, the vibration sound of the first panel may be a left side sound. The first flexible vibration module 300-1 may be configured as any one of the flexible vibration modules 300 according to the first to fifth examples of the present specification shown in FIGS. 3 to 11.

[0170] The first flexible vibration module 300-1 according to an embodiment may be arranged so as to be biased toward the center or end of the first region (A1) of the display panel 100 based on the first direction (X). The size of the first flexible vibration module 300-1 may be more than half the size of the first region (A1), but is not necessarily limited thereto, and may be set to more than half the size of the first region (A1) based on the acoustic characteristics required for the display device. For example, in the first region (A1) of the display panel 100, as the size of the first flexible vibration module 300-1 increases, the vibration region (or vibration area) of the first region (A1) increases, and the low-frequency range characteristics of the left sound may be improved. Conversely, in the first region (A1) of the display panel 100, as the size of the first flexible vibration module 300-1 decreases, the vibration region of the first region (A1) decreases, and the high-frequency range characteristics of the left sound may be improved. Therefore, the size of the first flexible vibration module 300-1 can be set according to the characteristics of the sound range required by the vibration of the display panel 100.

[0171] The second flexible vibration module 300-2 may be disposed in the first area (A2) of the display panel 100. The second flexible vibration module 300-2 may generate a vibration sound of the second panel or a second haptic feedback in the second area (A2) of the display panel 100 by vibrating the second area (A2) of the display panel 100. For example, the vibration sound of the second panel may be a right side sound. The second flexible vibration module 300-2 may be the same as the first flexible vibration module 300-1, but may be symmetrical to the first flexible vibration module 300-1 with respect to the center line (CL) of the display panel 100, and therefore a description thereof will be omitted.

[0172] According to one embodiment, the second flexible vibration module 300-2 may be arranged to be biased toward the center or edge of the second region (A2) of the display panel 100 based on the first direction (X), and may be arranged symmetrically to the first flexible vibration module 300-1 with respect to the midline (CL) of the display panel 100.

[0173] A display device according to another embodiment of the present specification can provide stereo sound to a user by outputting left and right sounds to the front of the display panel 100 via the first and second vibration modules 300-1, 300-2.

[0174] A display device according to another embodiment of the present specification may further include a partition 700 for separating a vibration area caused by the first flexible vibration module 300-1 from a vibration area caused by the second flexible vibration module 300-2.

[0175] The partition 700 according to the embodiment may include a first partition member 710 disposed between the first and second flexible vibration modules 300-1, 300-2.

[0176] The first partition member 710 is disposed on the rear center line (CL) of the display panel 100, and can separate the vibration of the first panel (or vibration sound of the panel) and the vibration of the second panel (or vibration sound of the panel) generated by the first flexible vibration module 300-1 and the second flexible vibration module 300-2. The first partition member 710 according to an example can spatially separate the gap space (GS) disposed between the display panel 100 and the rear structure 500 by being disposed between the rear center of the display panel 100. For example, the first partition member 710 can block (or prevent) the vibration generated in the first region (A1) of the display panel 100 by the first flexible vibration module 300-1 from being transmitted to the second region (A2) of the display panel 100, or can block (or prevent) the vibration generated in the second region (A2) of the display panel 100 by the second flexible vibration module 300-2 from being transmitted to the first region (A1) of the display panel 100. Thus, the first partition member 710 attenuates or absorbs vibrations of the display panel 100 at the center of the display panel 100, thereby blocking sound in the first area (A1) from being transmitted to the second area (A2) and blocking sound in the second area (A2) from being transmitted to the first area (A1). The first partition member 710 may be expressed as a central partition or sound separating member, a central enclosure, a central baffle, a partition wall, or the like, but is not limited thereto.

[0177] According to an embodiment, the first partition member 710 may be made of polyurethane and / or polyolefin. As another example, the first partition member 710 may be made of a one-sided tape or a double-sided tape, and may be made of a material having elasticity that can be compressed to a certain degree.

[0178] The first partition member 710 can further improve the acoustic output characteristics of the display device by separating left and right sounds, and a display device including the first partition member 710 can output stereo sound in two-channel mode to the front of the display panel 100 by separating the left and right sounds by the first partition member 710.

[0179] According to an embodiment, the partition 700 may further include a second partition member 720 surrounding the display panel 100 and the rear structure 500 .

[0180] The second partition member 720 may be disposed along between the rear edge (or the periphery of the rear edge) of the display panel 100 and the front edge (or the periphery of the front edge) of the rear structure 500 so as to surround the entire first and second flexible vibration modules 300-1 and 300-2. The second partition member 720 may be expressed as an edge partition or a sound blocking member, an edge enclosure, a baffle, or the like.

[0181] The second partition member 720, together with the first partition member 710, provides a first air gap (AG1) and a second air gap (AG2) between the display panel 100 and the rear structure 500. For example, each of the first air gap (AG1) and the second air gap (AG2) can be expressed as a vibration space, a sound pressure space, a sound body, a sounding part, a resonating tube, or a resonating part.

[0182] The first air gap (AG1) may be provided in a first region (A1) of the display panel 100 surrounded by a first partition member 710 and a second partition member 720 disposed in the first region (A1) of the display panel 100.

[0183] The second air gap (AG2) may be provided in the second region (A2) of the display panel 100 surrounded by the first partition member 710 and a second partition member 720 disposed in the second region (A2) of the display panel 100.

[0184] The first flexible vibration module 300-1 may be surrounded by a part of the second partition member 720 that provides the first air gap (AG1) and the first partition member 710, and the second flexible vibration module 300-2 may be surrounded by the remaining part of the second partition member 720 that provides the second air gap (AG2) and the first partition member 710. As another example, the second partition member 720 may be omitted.

[0185] The second partition member 720 may be present between the display panel 100 and the rear structure 500, and together with the first partition member 710, surrounds each of the first and second flexible vibration modules 300-1, 300-2 individually, thereby securing vibration space for each of the first and second flexible vibration modules 300-1, 300-2, increasing the sound pressure characteristics of the left and right sounds, and blocking the leakage of sound or sound pressure to the outside through the sides between the display panel 100 and the rear structure 500, thereby further improving the sound output characteristics of the display device.

[0186] The partition 700 according to the embodiment may further include a third partition member 730 surrounding the first flexible vibration module 300-1 and a fourth partition member 740 surrounding the second flexible vibration module 300-2.

[0187] The third partition member 730 is disposed between the display panel 100 and the rear structure 500 so as to overlap or correspond to the first air gap AG1, and may individually surround the first flexible vibration module 300-1. The third partition member 730 according to an embodiment may have a circular shape surrounding the first flexible vibration module 300-1, but is not limited thereto, and may have the same shape as the overall shape of the first flexible vibration module 300-1 or another shape. For example, if the first flexible vibration module 300-1 has a rectangular shape, the third partition member 730 may have a rectangular shape having a size relatively larger than that of the first flexible vibration module 300-1.

[0188] The third partition member 730 can limit (or define) the vibration region (or vibration area) of the display panel 100 by the first flexible vibration module 300-1. For example, in the first region (A1) of the display panel 100, as the size of the third partition member 730 increases, the vibration region of the first region (A1) increases, and the characteristics of the low frequency range of the left sound can be improved. Conversely, in the first region (A1) of the display panel 100, as the size of the third partition member 730 decreases, the vibration region of the first region (A1) decreases, and the characteristics of the high frequency range of the left sound can be improved. Therefore, the size of the third partition member 730 can be set according to the characteristics of the frequency range required by the vibration of the display panel 100.

[0189] The fourth partition member 740 may be disposed between the display panel 100 and the rear structure 500 to overlap with or correspond to the second air gap AG2, and may individually surround the second flexible vibration module 300-2. According to an example, the fourth partition member 740 may have the same shape as the third partition member 730 and may have a symmetrical structure with respect to the rear center line (CL) of the display panel 100 for symmetry between the left and right sides.

[0190] The fourth partition member 740 can limit (or define) the vibration region (or vibration area) of the display panel 100 by the second flexible vibration module 300-2. For example, in the second region (A2) of the display panel 100, as the size of the fourth partition member 740 increases, the vibration region of the second region (A2) increases, and the characteristics of the low frequency range of the right sound can be improved. Conversely, in the second region (A2) of the display panel 100, as the size of the fourth partition member 740 decreases, the vibration region of the second region (A2) decreases, and the characteristics of the high frequency range of the right sound can be improved. Therefore, the size of the fourth partition member 740 can be set according to the sound range characteristics required by the vibration of the display panel 100.

[0191] The third and fourth partition members 730, 740 limit the vibration regions (or vibration areas) of the flexible vibration modules 300-1, 300-2, thereby improving the left-right symmetry of the left and right sounds generated based on the vibration of the display panel 100, and optimizing the sound pressure characteristics and sound range reproduction band of each of the left and right sounds.

[0192] In some embodiments, one or more of the partitions 710, 720, 730 may be made of a double-sided or single-sided adhesive tape, for example, made of a material having elasticity that allows it to be compressed to a certain extent.

[0193] FIG. 14 shows the flexible vibration module and partition shown in FIG. 12, which is a modification of the first partition member shown in FIG.

[0194] 14, in a display device according to another embodiment of the present specification, a first partition member 710 may include first and second sub-partition members 711, 713 spaced apart from each other and disposed on a rear center line (CL) of the display panel 100. The first partition member 710 having the first and second sub-partition members 711, 713 may be expressed as at least one first partition member.

[0195] The first and second sub-partition members 711, 713 may be disposed between the rear center of the display panel 100 and the rear structure 500. For example, the first and second sub-partition members 711, 713 may be disposed side by side with each other between the rear center of the display panel 100 and the rear structure 500.

[0196] The first and second sub-partition members 711 , 713 , together with the second partition member 720 , provide first to third air gaps (AG 1 , AG 2 , AG 3 ) between the display panel 100 and the rear structure 500 .

[0197] The first air gap (AG1) may be provided in the first area (A1) of the display panel 100 surrounded by the first sub-partition member 711 and the second partition member 720 disposed in the first area (A1) of the display panel 100.

[0198] The second air gap (AG2) may be provided in the second region (A2) of the display panel 100 surrounded by the second sub-partition member 713 and the second partition member 720 disposed in the second region (A2) of the display panel 100.

[0199] The third air gap (AG3) may be provided in an intermediate region of the display panel 100 surrounded by the first and second sub-partition members 711 and 713 and the second partition member 720. For example, the third air gap (AG3) may be provided between the first air gap (AG1) and the second air gap (AG2) including the rear center line (CL) of the display panel 100. Such a third air gap (AG3) may be expressed as a sound separation space, a sound shielding space, or a sound interference prevention space. The third air gap (AG3) spatially separates the first air gap (AG1) and the second air gap (AG2) to prevent a resonance phenomenon or an interference phenomenon in a certain frequency band that occurs in each of the first air gap (AG1) and the second air gap (AG2). In another embodiment, the second partition member 720 may be omitted.

[0200] The first flexible vibration module 300-1 may be surrounded by a portion of the second partition member 720 providing a first air gap (AG1) and a first sub-partition member 711, and the second flexible vibration module 300-2 may be surrounded by the remaining portion of the second partition member 720 providing a second air gap (AG2) and a second sub-partition member 713.

[0201] The first partition member 710 having the first and second sub-partition members 711 and 713, together with the second partition member 720, provides the first air gap (AG1) and the second air gap (AG2) surrounding the first and second flexible vibration modules 300-1 and 300-2, respectively, and the third air gap (AG3) between the first air gap (AG1) and the second air gap (AG2), thereby securing vibration spaces for the first and second flexible vibration modules 300-1 and 300-2, increasing the sound pressure characteristics of the left and right sounds, and preventing the resonance phenomenon or interference phenomenon of the left and right sounds, thereby further increasing the sound pressure characteristics of the left and right sounds. This can further improve the sound output characteristics of the display device.

[0202] 15a to 15c are diagrams showing modified examples of the first and second flexible vibration modules shown in FIG. 14, in which the arrangement structure of the piezoelectric parts in the piezoelectric composite layer shown in FIG. 14 is changed.

[0203] 15a, in the first and second flexible vibration modules 300-1 and 300-2 according to the first modified example, the length of each of the piezoelectric parts 311 is similar to that of the flexible vibration module shown in FIG. 3 or 13, except that the length of each of the piezoelectric parts 311 gradually increases from the end (or periphery) of the display panel 100 toward the center line (CL) according to a length gradient. Therefore, each of the piezoelectric parts 311 according to the first modified example has a different vibration frequency according to each different length, thereby increasing the sound pressure characteristics of the left and right sounds generated by the vibration of the display panel 100, and expanding the sound reproduction band. In FIG. 15a to FIG. 15c, the second partition member 720 can be omitted.

[0204] 15b, in the first and second flexible vibration modules 300-1 and 300-2 according to the second modified example, the length of each of the piezoelectric parts 311 is similar to that of the flexible vibration module shown in FIG. 5, except that the length of each of the piezoelectric parts 311 gradually increases from the edge or periphery of the display panel 100 toward the center line (CL) according to a length gradient. As a result, each of the piezoelectric parts 311 according to the second modified example has a different vibration frequency according to each different length, thereby increasing the sound pressure characteristics of the left and right sounds generated by the vibration of the display panel 100, and expanding the sound reproduction band.

[0205] 15c, in the first and second flexible vibration modules 300-1 and 300-2 according to the third modified example, the width of each of the piezoelectric parts 311 is similar to that of the flexible vibration module shown in FIG. 7, except that the width of each of the piezoelectric parts 311 gradually increases from the edge or periphery of the display panel 100 toward the center line (CL) according to a width gradient. As a result, each of the piezoelectric parts 311 according to the third modified example has a different vibration frequency according to a different width, and therefore the sound pressure characteristics of the left and right sounds generated by the vibration of the display panel 100 can be increased, and the sound reproduction band can be expanded.

[0206] 16a to 16c are diagrams showing various display devices to which the flexible vibration module according to the embodiments of the present specification can be applied, which show display devices to which the flexible vibration module shown in FIGS. 3 to 11 can be applied.

[0207] The flexible vibration module according to the embodiments of the present disclosure is embodied in a flexible film form, and thus can be applied to various application devices.

[0208] Referring to FIG. 16a, the flexible vibration module 300 according to the embodiment of the present specification can be applied to a flexible display device or a commercial display apparatus having a display panel 100 including a plurality of concave or convex curved surface portions (CSPs). As an embodiment, the flexible vibration module 300 can be bent into a shape having a curvature value (or a curvature radius) that matches (or corresponds to) the convex or concave portion of each curved surface portion (CSP) of the display panel 100, and can be disposed in the convex or concave portion of each curved surface portion (CSP) of the display panel 100, respectively. As another example, the flexible vibration module 300 can have a shape that matches (or corresponds to) the curvature value (or a curvature radius) of each curved surface portion (CSP) of the display panel 100, and can be disposed on the entire back surface of the display panel 100.

[0209] 16b, the flexible vibration module 300 according to the embodiment of the present specification can be applied to a rollable display device having a display panel 100 wound or unwound in a spiral shape. As an embodiment, the flexible vibration module 300 can be embodied in a shape having a curvature value (or a curvature radius) of the display panel 100 wound or unwound in a spiral shape and can be arranged at regular intervals on the rear surface of the display panel 100. As another embodiment, the flexible vibration module 300 can be arranged over the entire rear surface of the display panel 100, having a shape that matches (or corresponds to) the curvature value (or a curvature radius) of the display panel 100 wound or unwound in a spiral shape.

[0210] 16c, the flexible vibration module 300 according to the embodiment of the present specification can be applied to a wearable display device having a display panel 100 bent in a "C" shape that is wrapped around a user's wrist. As an embodiment, the flexible vibration module 300 can have a shape having a curvature value (or curvature radius) of the display panel 100 bent in a "C" shape, and can be arranged at a certain interval (or distance) on the back surface of the display panel 100. As another embodiment, the flexible vibration module 300 can have a shape that matches (or corresponds to) the curvature value (or curvature radius) of the display panel 100 bent in a "C" shape, and can be arranged over the entire back surface of the display panel 100.

[0211] Fig. 17 is a graph showing the measurement of the sound pressure characteristic of a display panel according to an embodiment of the present specification and the sound pressure characteristic of a display panel according to a comparative example. The sound pressure measurement in Fig. 17 was performed using APx525 manufactured by Audio Precision, applying a sine sweep at 20Hz to 20kHz, and measuring the sound pressure at a position 50cm away from the display panel. The sine sweep may be a method of performing a sweep in a short period of time, and is not limited to this method. In Fig. 17, the horizontal axis (x-axis) indicates frequency (Hz), and the vertical axis (y-axis) indicates sound pressure (Sound Pressure Level, dB).

[0212] In one embodiment of this specification (thick solid line), a display panel in which no partition is arranged is prepared in the display device shown in Figure 15a, and in a comparative example (dotted line), a display panel is prepared in which flexible vibration modules including multiple piezoelectric parts having the same length without a length gradient are attached to the left and right regions, respectively.

[0213] 17, compared to the display panel according to the comparative example (dotted line), the display panel according to one embodiment of the present specification (thick solid line) has a sound pressure of 50 dB or more across the entire audible frequency range, and has a high sound pressure of about 10 dB in the treble range as well as in the bass range, and thus it can be seen that the dipping of sound pressure across the entire audible frequency range has been improved, and the flatness of sound pressure has been improved. Here, the flatness of the acoustic characteristics can be the magnitude of deviation between the maximum sound pressure and the minimum sound pressure.

[0214] Therefore, in the flexible vibration module and display device including the same according to the present specification, each of the multiple piezoelectric parts constituting the piezoelectric composite layer has various vibration frequencies according to the magnitude gradient, thereby increasing the sound pressure characteristics across the entire audible frequency range and expanding the sound reproduction band.

[0215] The flexible vibration module and the display device including the flexible vibration module according to the present specification can be applied to various applications. For example, the display panel including the flexible vibration module according to the present specification and the display device including the flexible vibration module can be applied to mobile devices, video phones, smart watches, watch phones, wearable devices, foldable devices, rollable devices, bendable devices, flexible devices, curved devices, electronic organizers, electronic books, portable multimedia players (PMPs), personal digital assistants (PDAs), MP3 players, mobile phones, medical devices, desktop PCs, laptop PCs, netbook computers, workstations, navigation systems, car navigation systems, vehicle display devices, televisions, wallpaper devices, signage devices, game devices, notebook computers, monitors, cameras, video cameras, and home appliances. In addition, the flexible vibration module of the present specification may be applied to an organic light-emitting lighting device or an inorganic light-emitting lighting device. When the flexible vibration module is applied to a lighting device, it may function as a light and a speaker. When the flexible vibration module of the present specification is applied to a mobile device, it may function as a speaker or a receiver.

[0216] The flexible vibration module and the display device including the same according to the present specification can be described as follows.

[0217] A flexible vibration module according to one example of the present specification includes a piezoelectric composite layer including a plurality of piezoelectric portions having piezoelectric properties and a flexible portion between the plurality of piezoelectric portions, and at least two of the plurality of piezoelectric portions can have different sizes.

[0218] According to some embodiments herein, each of the plurality of piezoelectric portions may have a different magnitude and a different frequency.

[0219] According to some embodiments herein, at least two of the plurality of piezoelectric portions may have different lengths, different widths, and different thicknesses.

[0220] According to some embodiments of the present specification, any one of the length, width, and thickness of each of the plurality of piezoelectric portions may gradually increase or decrease from at least one end of the piezoelectric composite layer toward the center of the piezoelectric composite layer.

[0221] According to some embodiments herein, any one of the length, width, and thickness of each of the plurality of piezoelectric portions may vary randomly between one end and the other end of the piezoelectric composite layer.

[0222] According to some embodiments of the present specification, any one of the length, width, and thickness of each of the multiple piezoelectric portions may gradually increase or decrease from one end of the piezoelectric composite layer to the other end opposite the one end.

[0223] According to some embodiments herein, each of the plurality of piezoelectric portions can include a lower piezoelectric portion and an upper piezoelectric portion on the lower piezoelectric portion.

[0224] According to some embodiments herein, each of the plurality of piezoelectric portions may have the same thickness.

[0225] According to some embodiments herein, at least two of the bottom piezoelectric portions can have different thicknesses.

[0226] According to some embodiments of the present specification, the multiple piezoelectric portions have the same thickness, and the thickness of each of the lower piezoelectric portions can vary gradually or randomly from one end of the piezoelectric composite layer to the other end opposite the one end.

[0227] The flexible vibration module according to an example of the present specification may further include an electrode between the lower piezoelectric portion and the upper piezoelectric portion.

[0228] A flexible vibration module according to one example of the present specification may further include a first electrode between the lower piezoelectric portion and the upper piezoelectric portion, a second electrode between the lower piezoelectric portion and the upper piezoelectric portion, and an insulating layer between the first electrode and the second electrode.

[0229] A flexible vibration module according to one example of the present specification includes a piezoelectric composite layer including a plurality of piezoelectric portions having piezoelectric properties and a flexible portion between the plurality of piezoelectric portions, and the piezoelectric composite layer can have a plurality of vibration frequencies.

[0230] According to some embodiments herein, at least two of the plurality of piezoelectric portions may have different frequencies.

[0231] According to some embodiments of the present disclosure, the vibration frequency of each of the plurality of piezoelectric portions may vary gradually or randomly from one end of the piezoelectric composite layer to the opposite other end.

[0232] According to some embodiments herein, each of the plurality of piezoelectric portions can include a lower piezoelectric portion and an upper piezoelectric portion on the lower piezoelectric portion.

[0233] According to some embodiments of the present specification, the multiple piezoelectric portions may have the same thickness, and the thickness of each lower piezoelectric portion may be gradually thicker or thinner from at least one end of the piezoelectric composite layer toward the center of the piezoelectric composite layer.

[0234] According to some embodiments herein, each of the plurality of piezoelectric portions may include an inorganic material, and the flexible portion may include at least one of an organic piezoelectric material and an organic non-piezoelectric material.

[0235] A display device according to one example of the present specification includes a flexible vibration module and a display panel having a display area that displays an image and vibrates due to vibration of the flexible vibration module, wherein the flexible vibration module includes a piezoelectric composite layer including a plurality of piezoelectric portions having piezoelectric properties and soft portions between the plurality of piezoelectric portions, and at least two of the plurality of piezoelectric portions can have different sizes.

[0236] A display device according to one example of the present specification includes a flexible vibration module and a display panel having a display area that displays an image and vibrates due to the vibration of the flexible vibration module, the flexible vibration module includes a piezoelectric composite layer including a plurality of piezoelectric portions having piezoelectric properties and soft portions between the plurality of piezoelectric portions, and the piezoelectric composite layer can have a plurality of vibration frequencies.

[0237] A display device according to an example of the present specification may further include a touch electrode for sensing a touch, and the flexible vibration module may vibrate in response to a touch.

[0238] According to some embodiments herein, each of the plurality of piezoelectric portions may include an inorganic material, and the flexible portion may include at least one of an organic piezoelectric material and an organic non-piezoelectric material.

[0239] According to some embodiments of the present specification, the display panel may include a first region and a second region, and the flexible vibration module may include a first flexible vibration module arranged in the first region of the display panel, and a second flexible vibration module arranged in the second region of the display panel.

[0240] A display device according to an example of the present specification may further include a rear structure arranged on the rear side of the display panel, and at least one partition member arranged between the display panel and the rear structure, and between the first flexible vibration module and the second flexible vibration module.

[0241] A display device according to one example of the present specification further includes a rear structure arranged on the rear side of the display panel, and a partition arranged between the display panel and the rear structure, and the partition can surround at least one of the first flexible vibration module and the second flexible vibration module.

[0242] A display device according to an example of the present specification further includes a different partition arranged between the display panel and the rear structure, and the different partition can surround the first flexible vibration module, the second flexible vibration module, and the partition.

[0243] The features, structures, effects, etc. described in the examples of the present specification are included in at least one example of the present specification, and are not necessarily limited to only one example. Furthermore, the features, structures, effects, etc. exemplified in at least one example of the present specification can be combined or modified in other examples by a person having ordinary skill in the art to which the present specification belongs. Therefore, the contents related to such combinations and modifications should be interpreted as being included in the scope of the present specification.

[0244] The present specification described above is not limited to the above-mentioned embodiments and the attached drawings, and it will be apparent to those skilled in the art to which the present specification pertains that multiple substitutions, modifications and changes are possible within the scope of the technical matters of the present specification. Therefore, the scope of the present specification is indicated by the claims set forth below, and all modifications or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present specification. [Explanation of symbols]

[0245] 100: Display panel 200: Adhesive material 300: Flexible vibration module 300-1: First flexible vibration module 300-2: Second flexible vibration module 310: Piezoelectric composite layer 311: Piezoelectric part 313: Soft part 320: 1st electrode layer 330: Second electrode layer 500: Rear structure 700: Partition 710: First partition member 711: First sub-partition member 713: Second sub-partition member 720: Second partition member

Claims

1. An acoustic generating device including a piezoelectric composite layer, the piezoelectric composite layer comprising: Multiple vibration parts a plurality of bends between the plurality of vibration portions; The vibration portions are spaced apart from one another along a first direction and have the same width, Each of the plurality of bent portions has the same width along the first direction, The plurality of vibration portions and the plurality of bending portions are arranged alternately, At least two of the plurality of vibration parts have different lengths along a second direction intersecting the first direction, The at least two of the plurality of vibration units have a bilaterally symmetrical structure with respect to a center portion in the first direction, and / or An acoustic generating device, wherein at least two of the plurality of vibration parts have a top-bottom symmetrical structure with respect to a central part in the second direction.

2. Each of the plurality of vibration portions has a first width; Each of the plurality of bends has a second width that is the same as or different from the first width.

2. The sound generating device of claim 1.

3. Each of the plurality of vibration parts has a different size and a different natural vibration frequency.

2. The sound generating device of claim 1.

4. Each of the plurality of vibration parts has a different length and a different thickness.

2. The sound generating device of claim 1.

5. The acoustic generating device of claim 1 , wherein one of the length and thickness of each of the plurality of vibration sections gradually increases or decreases in a direction from at least one end of the piezoelectric composite layer to a central portion of the piezoelectric composite layer.

6. 2. The sound generating device according to claim 1, wherein one of the length and the thickness of each of the plurality of vibration parts varies randomly between one end and the other end of the piezoelectric composite layer.

7. The sound generating device according to claim 1 , wherein one of the length and the thickness of each of the plurality of vibration sections gradually increases or decreases in a direction from one end of the piezoelectric composite layer toward the other end opposite the one end.

8. a first electrode disposed on a first surface of the piezoelectric composite layer and connected to the first surfaces of the vibration portions and the first surfaces of the bending portions; a second electrode disposed on a second surface of the piezoelectric composite layer and connected to the second surfaces of the vibration portions and the second surfaces of the bending portions; The sound generating device of claim 1 , wherein the first surface and the second surface each have a planar structure.

9. the piezoelectric composite layer further includes a dummy pattern configured to surround at least one of one side surface and another side surface of each of the plurality of vibration portions, The sound generating device according to claim 1 , wherein each of the plurality of bent portions is configured to be coupled to the dummy pattern.

10. 10. The sound generating device according to claim 9, wherein a size of the dummy pattern gradually changes in a direction from one end of the piezoelectric composite layer toward a center portion of the piezoelectric composite layer.

11. Each of the plurality of vibration units includes an inorganic material or a piezoelectric material; and / or The sound generating device of claim 1 , wherein each of the plurality of bends comprises at least one of an organic material, an organic polymer, an organic piezoelectric material, and an organic non-piezoelectric material.

12. An acoustic generating device including a piezoelectric composite layer, the piezoelectric composite layer comprising: A plurality of vibration parts and a plurality of bent parts between the plurality of vibration parts, The plurality of vibration portions and the plurality of bending portions are arranged alternately, Each of the plurality of vibration units is A lower vibration part; an upper vibration part having a thickness obtained by subtracting the thickness of the lower vibration part that overlaps the upper vibration part from the total thickness of the vibration part; the upper vibration part is on the lower vibration part, The lower vibration part and the upper vibration part have different thicknesses, At least two lower vibration sections of the plurality of vibration sections have different natural vibration frequencies, An acoustic generating device, wherein at least two upper vibration sections of the plurality of vibration sections have different natural vibration frequencies.

13. The lower vibration portion of each of the plurality of vibration portions has a different natural vibration frequency, The upper vibration portion of each of the plurality of vibration portions has a different natural vibration frequency.

13. The sound generating device of claim 12.

14. At least two of the plurality of vibration parts have different natural vibration frequencies; or Each of the plurality of vibration parts has a different natural vibration frequency.

13. The sound generating device of claim 12.

15. The sound-generating device of claim 12 , wherein a thickness of each of the at least two lower vibrating parts is different from a thickness of each of the at least two upper vibrating parts.

16. Each of the plurality of vibration parts has the same thickness, The sound generating device according to claim 12 , wherein the at least two lower vibrating parts and the at least two upper vibrating parts have different thicknesses within a total thickness of the corresponding piezoelectric part.

17. The sound generating device according to claim 12 , wherein the thickness of the lower vibrating portion of each of the plurality of vibrating portions varies gradually or randomly from one end of the piezoelectric composite layer to the other end opposite the one end.

18. The sound generating device of claim 12 , wherein the thickness of the lower vibrating portion of each of the plurality of vibrating portions varies gradually or randomly in a direction from at least one end of the piezoelectric composite layer to a central portion of the piezoelectric composite layer.

19. a first electrode disposed on a first surface of the piezoelectric composite layer and connected to the first surfaces of the vibration portions and the first surfaces of the bending portions; a second electrode disposed on a second surface of the piezoelectric composite layer and connected to the second surfaces of the vibration portions and the second surfaces of the bending portions; The sound generating device of claim 12 , further comprising a counter electrode between the lower vibrating part and the upper vibrating part.

20. a first counter electrode between the lower vibration part and the upper vibration part; a second counter electrode between the lower vibration portion and the upper vibration portion; and an insulating layer between the first counter electrode and the second counter electrode.

13. The sound generating device of claim 12.

21. Each of the plurality of vibration parts includes an inorganic material or a piezoelectric material. and / or each of the plurality of bends comprises at least one of an organic material, an organic polymer, an organic piezoelectric material, and an organic non-piezoelectric material; 13. The sound generating device of claim 12.

22. A display device, comprising: a display panel including a display area configured to display video; and a sound generating device configured to vibrate the display panel, The sound generating device is A piezoelectric composite layer, A plurality of vibration units; a plurality of bends between the plurality of vibration portions; The plurality of vibration portions and the plurality of bending portions are arranged alternately, The vibration portions are spaced apart from one another along a first direction and have the same width, Each of the plurality of bent portions has the same width along the first direction, At least two of the plurality of vibration parts have different lengths along a second direction intersecting the first direction, At least two of the plurality of vibration units have a bilaterally symmetrical structure with respect to a center portion in the first direction, and / or A display device comprising a piezoelectric composite layer, wherein at least two of the plurality of vibration sections have a top-bottom symmetrical structure with respect to a central portion in the second direction.

23. Each of the plurality of vibration portions has a first width; Each of the plurality of bends has a second width that is the same as or different from the first width. The display device according to claim 22.

24. a display panel including a display area configured to display video; and a sound generating device configured to vibrate the display panel, The sound generating device includes a piezoelectric composite layer including a plurality of vibration portions and a plurality of bending portions between the plurality of vibration portions, The plurality of vibration portions and the plurality of bending portions are arranged alternately, Each of the plurality of vibration units is A lower vibration part; an upper vibration part having a thickness obtained by subtracting the thickness of the lower vibration part that overlaps the upper vibration part from the total thickness of the vibration part; the upper vibration part is on the lower vibration part, The lower vibration part and the upper vibration part have different thicknesses, At least two lower vibration sections of the plurality of vibration sections have different natural vibration frequencies, At least two upper vibration parts of the plurality of vibration parts have different natural vibration frequencies. Display device.

25. the lower vibration portion of each of the plurality of vibration portions has a different natural vibration frequency, The upper vibration portion of each of the plurality of vibration portions has a different natural vibration frequency. The display device according to claim 24.

26. At least two of the plurality of vibration parts have different natural vibration frequencies; or Each of the plurality of vibration parts has a different natural vibration frequency. The display device according to claim 24.

27. The display device according to claim 24 , wherein a thickness of each of the at least two lower vibration portions is different from a thickness of each of the at least two upper vibration portions.

28. the display panel comprises a touch electrode configured to sense touch; the sound generating device is configured to vibrate in response to the touch; 25. The display device according to claim 22 or 24.

29. the display panel has a first region and a second region; The sound generating device is a first sound-generating device in the first area of ​​the display panel; a second sound-generating device in the second area of ​​the display panel.

25. The display device according to claim 22 or 24.

30. a rear structure on a rear surface of the display panel; 30. The display device of claim 29, further comprising at least one partition member between the display panel and the rear structure and between the first sound-generating device and the second sound-generating device.

31. Each of the plurality of vibration units includes an inorganic material or a piezoelectric material. and / or 25. The display device of claim 22 or 24, wherein each of the plurality of flexures comprises at least one of an organic material, an organic polymer, an organic piezoelectric material, and an organic non-piezoelectric material.

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