Patent Description:
As our information society develops, the demand for display devices for displaying images has increased and diversified. For example, display devices have been applied to a variety of electronic devices such as smart phones, digital cameras, notebook computers, navigation devices, and smart televisions (TVs). A display device may include a display panel for displaying images and a sound generating device for providing sounds.

As display devices are increasingly applied to various electronic devices, display devices having various designs are required. For example, for a smart phone, a display device capable of increasing the size of the display area by eliminating a sound generating device, which is for outputting the voice of the other party during a call, from the front surface thereof is required. Reference is made to <CIT>, <CIT>, and <CIT>. <CIT> discloses a display device comprising two sound generating devices overlapping in a thickness direction and responsive to different frequency bands.

Devices constructed according to exemplary implementations of the invention are capable of providing not only sounds with the use of sound generating devices that are not exposed to the outside, but also capable of providing haptic feedback to a user.

Also, methods according to exemplary implementations of the invention are also capable of not only driving a display device to provide sounds with the use of integrated, sound generating devices, but also capable of providing haptic feedback to a user.

According to the aforementioned and other exemplary embodiments of the invention, sounds can be provided using first and second sound generating devices, such as speakers, which are disposed under a display panel, and haptic feedback can be provided to a user by vibrating the second sound generating device. Accordingly, since a front speaker does not need to be provided at the front surface of a display device, the display area of the display device can be increased.

In addition, the first sound generating device is formed as a piezoelectric actuator, having a high sound pressure level in a high frequency range and the second sound generating device is formed as a device, such as a linear resonant actuator (LRA), having a high sound pressure level in a low frequency range, sounds having a high sound pressure level in both the low and high frequency ranges can be provided to a user.

According to the invention, a display device including: a display panel; and first and second sound generating devices configured to generating sounds and vibrate the display panel, wherein the first sound generating device has a higher sound pressure level than the second sound generating device in a first frequency range, and the second sound generating device has a higher sound pressure level than the first sound generating device in a second frequency range lower than the first frequency range, wherein the first sound generating device and the second sound generating device at least partially overlap each other in a thickness direction of the display panel. The first sound generating device includes a piezoelectric actuator, and the second sound generating device includes an actuator by pressing a mass connected to a spring via a voice coil.

At least one of the sound generating devices may be integrated in the display device, that is, the at least one of the sound generating devices may be positioned between a lower cover and a cover window of the display device.

The sound generating devices may be disposed below the display panel.

The first sound generating device and the second sound generating device at least partially may overlap each other vertically.

The second sound generating device may be disposed below the first sound generating device.

The first sound generating device may include: a first electrode to which a first driving voltage is applied; a second electrode to which a second driving voltage is applied; and a vibration layer which is disposed between the first and second electrodes and contracts or expands in in response to the first and second driving voltages applied to the first and second electrodes, respectively.

The first electrode may include: a first stem electrode; and first branch electrodes branched off from the first stem electrode, and wherein the second electrode may include: a second stem electrode; and second branch electrodes which are branched off from the second stem electrode, the second branch electrode extending substantially parallel to the first branch electrodes.

The first branch electrodes and the second branch electrodes may be alternately arranged along a direction substantially parallel to the first stem electrode.

The first stem electrode may be disposed on one side of the vibration layer, and the second stem electrode may be disposed on the other side of the vibration layer.

The vibration layer may include first and second contact holes penetrating the vibration layer, wherein the first stem electrode may be disposed in the first contact hole penetrating the vibration layer, and wherein the second stem electrode may be disposed in the second contact hole penetrating the vibration layer.

The first sound generating device may include: a first pad electrode connected to the first electrode; and a second pad electrode connected to the second electrode.

The display device may further include: a first sound circuit board connected to the first and second pad electrodes; and a second sound circuit board connected to the second sound pad electrode of the second sound generating device.

The display device may further include: a middle frame disposed below the display panel, and having first and second through holes penetrating the middle frame.

The display device may further include: a main circuit board disposed below the middle frame and including first and second sound connectors.

One end of the first sound circuit board may be connected to the first sound connector through the first through hole of the middle frame, and one end of the second sound circuit board is connected to the second sound connector through the second through hole of the middle frame.

The main circuit board may include: a first sound driving unit configured to transmit the first and second driving voltages to the first sound generating device; a second sound driving unit configure to transmit an alternating current voltage to the second sound generating device; and a main processor configured to transmit first sound data to the first sound driving unit and transmit second sound data or haptic data to the second sound generating device.

The display device may further include: a display circuit board attached to one side of the display panel; and a connection cable connected to a connector of the display circuit board, wherein the connection cable may be connected to a main connector of the main circuit board through a third through hole which penetrates the middle frame.

The first and second sound connectors may be disposed on one surface of the main circuit board, and wherein the main processor may be disposed on the other surface of the main circuit board.

The first sound generating device may be configured to vibrate in a vertical direction with respect to the surface of the display panel, and the second sound generating device is configured to vibrate in a horizontal direction with respect to the surface of the display panel.

The first and second sound generating devices may be configured to vibrate in a vertical direction with respect to the surface of the display panel.

The display device may further include: a member connecting one side of the first sound generating device and one side of the second sound generating device.

According to the invention, a method is provided. The method is defined by claim <NUM>.

The display device may include a display panel and generating sounds in the sound output mode includes vibrating the display panel.

The display device may include a display panel and generating haptic feedback in the haptic mode includes vibrating the display panel.

The display device may further include a processor generating output signals driving the first and second sound generating devices in either the sound generating mode or the haptic mode.

Further, the D <NUM>-axis, the D2-axis, and the D3 -axis are not limited to three axes of a rectangular coordinate system, such as the x, y, and z - axes, and may be interpreted in a broader sense.

<FIG> is a perspective view of a display device construed according to an exemplary embodiment of the invention. <FIG> is an exploded perspective view of the display device of <FIG>.

Referring to <FIG> and <FIG>, a display device <NUM> includes a cover window <NUM>, a touch sensing device <NUM>, a touch circuit board <NUM>, a touch driving unit <NUM>, a display panel <NUM>, a display circuit board <NUM>, a display driving unit <NUM>, a panel bottom support <NUM>, a first sound generating device <NUM>, a second sound generating device <NUM>, a middle frame <NUM>, a main circuit board <NUM>, and a lower cover <NUM>.

The terms "above", "top", and "top surface", as used herein, denote a direction in which the cover window <NUM> is disposed with respect to the display panel <NUM>, i.e., a Z-axis direction, and the terms "below", "bottom", and "bottom surface", as used herein, denote a direction in which the middle frame <NUM> is disposed with respect to the display panel <NUM>, i.e., the direction opposite to the Z-axis direction. Also, the terms "left", "right", "upper", and "lower", as used herein, denote corresponding directions as viewed from above the display panel <NUM>. For example, the term "left" denotes the direction opposite to an X-axis direction, the term "right" denotes the X-axis direction, the term "upper" denotes a Y-axis direction, and the term "lower" denotes the direction opposite to the Y-axis direction.

The display device <NUM> may have a substantially rectangular shape in a plan view. For example, in a plan view, the display device <NUM> may have a substantially rectangular shape having short sides extending in a first direction (or the X-axis direction) and long sides extending in a second direction (or a Y-axis direction). The corners where the short sides and the long sides meet may be rounded or right-angled. The planar shape of the display device <NUM> is not particularly limited, and the display device <NUM> may be formed in various other shapes such as a polygonal shape other than a rectangular shape, a circular shape, or an elliptical shape.

The display device <NUM> may include a first area DR1, which is substantially flat, and second areas DR2, which extend from the left and right sides of the first area DR1. The second areas DR2 may be substantially flat or curved. In a case where the second areas DR2 are flat, the first area DR1 and the second areas DR2 may form an obtuse angle with each other. In a case where the second areas DR2 are curved, the second areas DR2 may have a predetermined curvature or a variable curvature.

<FIG> illustrates the second areas DR2 as extending from the left and right sides of the first area DR1, but the exemplary embodiments are not limited thereto. That is, the second areas DR2 may extend from only one of the left and right sides of the first area DR1. The second areas DR2 may also extend not only from the left and right sides, but also from the top and bottom sides of the first area DR1. In the description that follows, it is assumed that the second areas DR2 are disposed along the left and right edges of the display device <NUM>.

The cover window <NUM> may be disposed on the display panel <NUM> to cover the top surface of the display panel <NUM>. Accordingly, the cover window <NUM> may protect the top surface of the display panel <NUM>. As illustrated in <FIG>, the cover window <NUM> may be attached to the touch sensing device <NUM> via a first adhesive member <NUM>. The first adhesive member <NUM> may be an optically clear adhesive (OCA) or an optically clear resin (OCR).

The cover window <NUM> may include a light-transmitting portion DA100, which corresponds to the display panel <NUM>, and a light-blocking portion NDA100, which corresponds to the rest of the display device <NUM>. The cover window <NUM> may be disposed in the first area DR1 and the second areas DR2. The light-transmitting portion DA100 may be disposed in parts of the first area DR1 and the second areas DR2. The light-blocking portion NDA100 may be formed to be opaque. In a case where the light-blocking portion NDA100 does not display an image, the light-blocking portion NDA100 may be formed as a decorative layer that can be seen by a user. For example, a company's logo such as SAMSUNG ® or a string of various characters or letters may be patterned into the light-blocking portion NDA100. Also, holes HH, which are for exposing a front camera, a front speaker, an infrared (IR) sensor, an iris recognition sensor, and an illumination sensor, may be formed in the light-blocking portion NDA100, but the exemplary embodiments are not limited thereto. For example, some or all of the front camera, the front speaker, the IR sensor, the iris recognition sensor, and the illumination sensor may be integrated in the display panel <NUM>, in which case, some or all of the holes HH may not be provided.

The cover window <NUM> may be formed of glass, sapphire, and/or plastic. The cover window <NUM> may be formed to be rigid or flexible.

The touch sensing device <NUM> may be disposed between the cover window <NUM> and the display panel <NUM>. The touch sensing device <NUM> may be disposed in the first area DR1 and the second areas DR2. Accordingly, touch input from the user can be detected not only in the first area DR1, but also in the second areas DR2.

As illustrated in <FIG>, the touch sensing device <NUM> may be attached to the bottom surface of the cover window <NUM> via the first adhesive member <NUM>. A polarizing film may be added to the top of the touch sensing device <NUM> to prevent or reduce the degradation of visibility that may be caused by the reflection of external light. In this case, the polarizing film may be attached to the bottom surface of the cover window <NUM> via the first adhesive member <NUM>.

The touch sensing device <NUM>, which is a device for detecting the location of touch input from the user, may be implemented as being of a capacitive type such as a self-capacitance type or a mutual capacitance type. In a case where the touch sensing device <NUM> is implemented as being of the self-capacitance type, the touch sensing device <NUM> may include only touch driving electrodes. In a case where the touch sensing device <NUM> is implemented as being of the mutual capacitance type, the touch sensing device <NUM> may include touch driving electrodes and touch sensing electrodes. In the description that follows, it is assumed that the touch sensing device <NUM> is of the mutual capacitance type.

The touch sensing device <NUM> may be formed as a panel or a film. In this case, the touch sensing device <NUM> may be attached to a thin-film encapsulation film of the display panel <NUM> via a second adhesive member <NUM>, as illustrated in <FIG>. The second adhesive member <NUM> may be an OCA or an OCR.

The touch sensing device <NUM> may be formed in one integral body with the display panel <NUM>. In this case, the touch driving electrodes and the touch sensing electrodes of the touch sensing device <NUM> may be formed on the thin-film encapsulation film of the display panel <NUM> or on an encapsulation substrate or film covering a light-emitting element layer of the display panel <NUM>.

The touch circuit board <NUM> may be attached to one side of the touch sensing device <NUM>. Specifically, one end of the touch circuit board <NUM> may be attached to pads provided on one side of the touch sensing device <NUM> via an anisotropic conductive film. As illustrated in <FIG>, a touch connecting portion may be provided at the other end of the touch circuit board <NUM> and may be connected to a touch connector 312a of the display circuit board <NUM>. The touch circuit board <NUM> may be a flexible printed circuit board.

The touch driving unit <NUM> may apply touch driving signals to the touch driving electrodes of the touch sensing device <NUM>, may detect sensing signals from the touch sensing electrodes of the touch sensing device <NUM>, and may calculate or detect the location of touch input from the user by analyzing the detected sensing signals. The touch driving unit <NUM> may be formed as an integrated circuit and may be mounted on the touch circuit board <NUM>.

The display panel <NUM> may be disposed below the touch sensing device <NUM>. The display panel <NUM> may be disposed to overlap with the light-transmitting portion 100DA of the cover window <NUM>. The display panel <NUM> may be disposed in the first area DR1 and the second areas DR2. As a result, an image from the display panel <NUM> can be seen in the first area DR1 and in the second areas DR2.

The display panel <NUM> may be a light-emitting display panel including light-emitting elements. For example, the display panel <NUM> may be an organic light-emitting diode (OLED) display panel using OLEDs, a micro-light-emitting diode (mLED) display panel using mLEDs, or a quantum-dot light-emitting diode (QLED) display panel using QLEDs or be a panel using other types of light emitting elements. In the description that follows, it is assumed that the display panel <NUM> is an OLED display panel as illustrated in <FIG>.

Referring to <FIG>, a display area DA of the display panel <NUM> is an area in which a light-emitting element layer <NUM> is formed and an image is displayed, and a non-display area NDA of the display panel <NUM> is an area which is on the periphery of the display area DA.

The display panel <NUM> may include a supporting substrate <NUM>, a flexible substrate <NUM>, a thin-film transistor (TFT) layer <NUM>, the light-emitting element layer <NUM>, an encapsulation layer <NUM>, and a barrier film <NUM>.

The flexible substrate <NUM> is disposed on the supporting substrate <NUM>. The supporting substrate <NUM> and the flexible substrate <NUM> may include a polymer material having flexibility. For example, the supporting substrate <NUM> and the flexible substrate <NUM> may include polyethersulphone (PES), polyacrylate (PA), polyarylate (PAR), polyetherimide (PEI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyallylate, polyimide (PI), polycarbonate (PC), cellulose triacetate (CAT), cellulose acetate propionate (CAP), or a combination thereof.

The TFT layer <NUM> is formed on the flexible substrate <NUM>. The TFT layer <NUM> includes TFTs <NUM>, a gate insulating film <NUM>, an interlayer insulating film <NUM>, a passivation film <NUM>, and a planarization film <NUM>.

A buffer film may be formed on the flexible substrate <NUM>. The buffer film may be formed on the flexible substrate <NUM> to protect the TFTs <NUM> and the light-emitting elements against moisture that may penetrate the supporting substrate <NUM> and the flexible substrate <NUM>, which are susceptible to moisture. The buffer film may consist of a plurality of inorganic films that are alternately stacked. For example, the buffer film may be formed as a multilayer film in which at least one of a silicon oxide (SiOx) film and a silicon nitride (SiNx) film is alternately stacked. The buffer layer may not be provided.

The TFTs <NUM> are formed on the buffer film. Each of the TFTs <NUM> includes an active layer <NUM>, a gate electrode <NUM>, a source electrode <NUM>, and a drain electrode <NUM>. <FIG> illustrates the TFTs <NUM> as having a top gate structure in which the gate electrode <NUM> is disposed above the active layer <NUM>, but the exemplary embodiments are not limited thereto. That is, the TFTs <NUM> may have a bottom gate structure in which the gate electrode <NUM> is disposed below the active layer <NUM> or a double gate structure in which the gate electrode <NUM> is disposed both above and below the active layer <NUM>.

The active layer <NUM> is formed on the buffer film. The active layer <NUM> may be formed of a silicon-based semiconductor material or an oxide-based semiconductor material. A light-shielding layer for blocking external light incident on the active layer <NUM> may be formed between the buffer layer and the active layer <NUM>.

A gate insulating film <NUM> may be formed on the active layer <NUM>. The gate insulating film <NUM> may be formed as an inorganic film such as, for example, a silicon oxide film, a silicon nitride film, or a multilayer film thereof.

The gate electrode <NUM> and a gate line may be formed on the gate insulating film <NUM>. The gate electrode <NUM> and the gate line may be formed as single- or multilayer films using molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Ne), copper (Cu), or an alloy thereof.

The interlayer insulating film <NUM> may be formed on the gate electrode <NUM> and the gate line. The interlayer insulating film <NUM> may be formed as an inorganic film such as, for example, a silicon oxide film, a silicon nitride film, or a multilayer film thereof.

The source electrode <NUM>, the drain electrode <NUM>, and a data line may be formed on the interlayer insulating film <NUM>. The source electrode <NUM> and the drain electrode <NUM> may be connected to the active layer <NUM> through contact holes penetrating the gate insulating film <NUM> and the interlayer insulating film <NUM>. The source electrode <NUM>, the drain electrode <NUM>, and the data line may be formed as single- or multilayer films using Mo, Al, Cr, Au, Ti, Ni, Ne, Cu, or an alloy thereof.

The passivation film <NUM> may be formed on the source electrode <NUM>, the drain electrode <NUM>, and the data line to insulate the TFTs <NUM>. The passivation film <NUM> may be formed as an inorganic film such as, for example, a silicon oxide film, a silicon nitride film, or a multilayer film thereof.

The planarization film <NUM> may be formed on the passivation film <NUM> to planarize height differences formed by the TFTs <NUM>. The planarization film <NUM> may be formed as an organic film using an acrylic resin, an epoxy resin, a phenolic resin, a polyamide resin, or a polyimide resin.

The light-emitting element layer <NUM> is formed on the TFT layer <NUM>. The light-emitting element layer <NUM> includes the light-emitting elements and a pixel-defining film <NUM>.

The light-emitting elements and the pixel-defining film <NUM> are formed on the planarization film <NUM>. The light-emitting elements may be OLEDs. In this case, each of the light-emitting elements may include an anode electrode <NUM>, a light-emitting layer <NUM>, and a cathode electrode <NUM>.

The anode electrode <NUM> may be formed on the planarization film <NUM>. The anode electrode <NUM> may be connected to the source electrode <NUM> through a contact hole penetrating the passivation film <NUM> and the planarization film <NUM>.

The pixel-defining film <NUM> may be formed to cover the edges of the anode electrode <NUM> to define a corresponding pixel. That is, the pixel-defining film <NUM> may define each pixel. Each pixel may be a region in which the anode electrode <NUM>, the light-emitting layer <NUM>, and the cathode electrode <NUM> are sequentially stacked and holes from the anode electrode <NUM> and electrons from the cathode electrode <NUM> are combined in the light-emitting layer <NUM> to emit light.

The light-emitting layer <NUM> may be formed on the anode electrode <NUM> and the pixel-defining film <NUM>. The light-emitting layer <NUM> may be an organic light-emitting layer. The light-emitting layer <NUM> may emit or generate one of red light, green light, and blue light. The peak wavelength of the red light may range from about <NUM> to <NUM>, the peak wavelength of the green light may range from about <NUM> to <NUM>, and the peak wavelength of the blue light may range from about <NUM> to <NUM>. The light-emitting layer <NUM> may be a white light-emitting layer to emit or generate white light. In this case, the light-emitting layer <NUM> may have a stack of red, green, and blue light-emitting layers and may be a common layer formed commonly for all pixels. Also, in this case, the display panel <NUM> may further include color filters for displaying red, green, and blue colors.

The light-emitting layer <NUM> may include a hole transport layer, an emission layer, and an electron transport layer. The light-emitting layer <NUM> may have a tandem structure with two or more stacks, in which case, a charge generating layer may be formed between the stacks.

The cathode electrode <NUM> may be formed on the light-emitting layer <NUM>. The cathode electrode <NUM> may be formed to cover the light-emitting layer <NUM>. The cathode electrode <NUM> may be a common layer formed commonly for all pixels.

In a case where the light-emitting element layer <NUM> is formed as a top emission-type light-emitting element layer, the anode electrode <NUM> may be formed of a metal material with high reflectance such as a stack of Al and Ti (e.g., Ti/Al/Ti), a stack of Al and ITO (e.g., ITO/Al/ITO), a silver (Ag)-palladium (Pd)-copper (Cu) (APC) alloy, or a stack of an APC alloy and ITO (e.g., ITO/APC/ITO), and the cathode electrode <NUM> may be formed of a transparent conductive oxide (TCO) material such as ITO or IZO that can transmit light therethrough or a semi-transmissive conductive material such as magnesium (Mg), Ag, or an alloy thereof. In a case where the cathode electrode <NUM> is formed of a semi-transmissive conductive material, the emission efficiency of the light-emitting element layer <NUM> may be improved due to a micro-cavity effect.

In a case where the light-emitting element layer <NUM> is formed as a bottom emission-type light-emitting element layer, the anode electrode <NUM> may be formed of a TCO material such as ITO or IZO or a semi-transmissive conductive material such as Mg, Ag, or an alloy thereof, and the cathode electrode <NUM> may be formed of a metal material with high reflectance such as a stack of Al and Ti (e.g., Ti/Al/Ti), a stack of Al and ITO (e.g., ITO/Al/ITO), an APC alloy, or a stack of an APC alloy and ITO (e.g., ITO/APC/ITO). In a case where the anode electrode <NUM> is formed of a semi-transmissive conductive material, the emission efficiency of the light-emitting element layer <NUM> may be improved due to a micro-cavity effect.

The encapsulation layer <NUM> is formed on the light-emitting element layer <NUM>. The encapsulation layer <NUM> prevents or reduces the penetration of oxygen or moisture into the light-emitting layer <NUM> and the cathode electrode <NUM>. The encapsulation layer <NUM> may include at least one inorganic film. The inorganic film may be formed of silicon nitride, aluminum nitride, zirconium nitride, titanium nitride, hafnium nitride, tantalum nitride, silicon oxide, aluminum oxide, or titanium oxide. The encapsulation layer <NUM> may further include at least one organic film. The organic layer may be formed to a sufficient thickness to prevent or reduce particles from entering the light-emitting layer <NUM> and the cathode electrode <NUM> through the encapsulation layer <NUM>. The organic film may include one of epoxy, acrylate, and urethane acrylate.

The display circuit board <NUM> may be attached to one side of the display panel <NUM>. Specifically, one end of the display circuit board <NUM> may be attached to pads provided on one side of the display panel <NUM> via an anisotropic conductive film. The display circuit board <NUM> may be bent toward the bottom surface of the display panel <NUM>. The touch circuit board <NUM> may also be bent toward the bottom surface of the display panel <NUM>. As a result, the touch connecting portion provided at the touch circuit board <NUM> may be connected to the touch connector 312a of the display circuit board <NUM>. The display circuit board <NUM> will be described later with reference to <FIG>, <FIG>, and <FIG>.

The display driving unit <NUM> outputs or transmits, via the display circuit board <NUM>, signals and voltages for driving the display panel <NUM>. The display driving unit <NUM> may be formed as an integrated circuit and may be mounted on the display circuit board <NUM>, but the exemplary embodiments are not limited thereto. For example, the display driving unit <NUM> may be attached directly to the display panel <NUM>, in which case, the display driving unit <NUM> may be attached to the top surface or the bottom surface of the display panel <NUM>.

The panel bottom support <NUM> may be disposed below the display panel <NUM>, as illustrated in <FIG>. The panel bottom support <NUM> may be attached to the bottom surface of the display panel <NUM> via a third adhesive member <NUM>. The third adhesive member <NUM> may be an OCA or an OCR.

The panel bottom support <NUM> may include at least one of a light-absorbing member for absorbing incident light from the outside, a buffer member for absorbing shock from the outside, a heat dissipation member for effectively releasing heat from the display panel <NUM>, and a light-shielding layer for blocking incident light from the outside.

The light-absorbing member may be disposed below the display panel <NUM>. The light-absorbing member blocks the transmission of light and thus prevents or reduces the elements disposed therebelow, i.e., the first sound generating device <NUM>, the second sound generating device <NUM>, and the display circuit board <NUM>, from becoming visible from above the display panel <NUM>. The light-absorbing member may include a light-absorbing material such as a black pigment or dye.

The buffer member may be disposed below the light-absorbing member. The buffer member absorbs shock from the outside and thus prevents or reduces the display panel <NUM> from being damaged due to impacts and the like. The buffer member may be formed as a single layer or as multiple layers. For example, the buffer member may include a polymer resin such as polyurethane, polycarbonate, polypropylene, or polyethylene or an elastic material such as a sponge obtained by foam-molding rubber, a urethane-based material or an acrylic material. The buffer member may be a cushion layer.

The heat dissipation member may be disposed below the buffer member. The heat dissipation member may include a first heat dissipation layer including graphite or carbon nanotubes and a second heat dissipation layer formed as a thin metal film using a metal having excellent or high thermal conductivity such as Cu, Ni, ferrite, or Ag.

The first and second sound generating devices <NUM> and <NUM> may be disposed below the panel bottom support <NUM>. The first and second sound generating devices <NUM> and <NUM> completely or partially overlap each other vertically. In this case, the first sound generating device <NUM> may be attached to the bottom surface of the panel bottom support <NUM>, and the second sound generating device <NUM> may be attached to the bottom surface of the first sound generating device <NUM>. The first sound generating device <NUM> may be attached to the bottom surface of the panel bottom support <NUM> via a fourth adhesive member <NUM>, and the second sound generating device <NUM> may be attached to the bottom surface of the first sound generating device <NUM> via a fifth adhesive member <NUM>. The fourth adhesive member <NUM> and the fifth adhesive member <NUM> may be pressure sensitive adhesives (PSAs).

In a case where the first sound generating device <NUM> is disposed on the heat dissipation member of the panel bottom support <NUM>, the first or second heat dissipation layer of the heat dissipation member may break or be damaged due to the vibration of the first sound generating device <NUM>. Accordingly, the heat dissipation member may be removed in the region where the first sound generating device <NUM> is disposed, and the first sound generating device <NUM> may be disposed on the buffer member. As illustrated in <FIG>, the panel bottom support <NUM> may be removed in the region where the first sound generating device <NUM> is disposed, and the first sound generating device <NUM> may be disposed on the bottom surface of the display panel <NUM>.

The first and sound generating devices may take the form of a speaker, vibrator, actuator or any other device that can generate vibration in response to an acoustic signal. Some specific examples of the type of sound generating devices that may be employed include those discussed herein. The first sound generating device <NUM> includes a piezoelectric actuator. The first sound generating device <NUM> may vibrate by applying an alternating current (AC) voltage to the piezoelectric actuator so as for the piezoelectric actuator to contract and expand. Due to the vibration of the first sound generating device <NUM>, the display panel <NUM> may vibrate vertically to output sounds.

The second sound generating device <NUM> may be an eccentric rotating motor (ERM) or a linear resonant actuator (LRA). An ERM is driven by a direct current (DC) voltage, and an LRA may be driven by an AC voltage. The second sound generating device <NUM> vibrates by pressing a mass connected to a spring via a voice coil in response to an AC voltage being applied. As the second sound generating device <NUM> vibrates, the display panel <NUM> may vibrate vertically to output sounds. As the second sound generating device <NUM> vibrates, the display panel <NUM> may vibrate to provide haptic feedback to the user.

The first sound generating device <NUM> has a higher sound pressure level than the second sound generating device <NUM> in a comparatively high frequency range, and the second sound generating device <NUM> has a higher sound pressure level than the first sound generating device <NUM> in a comparatively low or lower frequency range. According to a preferred embodiment, the low frequency range refers to a range of frequencies of <NUM> or lower, and the high frequency range refers to a range of frequencies higher than <NUM>. Since sounds are generated using the first sound generating device <NUM>, which has a high sound pressure level in the high frequency range, and using the second sound generating device <NUM>, a high sound level can be provided for both the high frequency range and the low frequency range. The second sound generating device <NUM> may vibrate at a higher amplitude when providing haptic feedback to the user than when outputting sounds.

The first sound generating device <NUM> may be connected to a first sound circuit board <NUM>, and the second sound generating device <NUM> may be connected to a second sound circuit board <NUM>. Specifically, one end of the first sound generating board <NUM> may be connected to a first sound pad area provided at at least one side of the first sound generating device <NUM>, and one end of the second sound generating board <NUM> may be connected to a second sound pad area provided at at least one side of the second sound generating device <NUM>.

The first sound circuit board <NUM> may be connected to a first sound connector <NUM> of the main circuit board <NUM>. As a result, the first sound generating device <NUM> may be connected to a first sound driving unit <NUM> of the main circuit board <NUM>. Accordingly, the first sound generating device <NUM> can vibrate according to first and second driving voltages from the first sound driving unit <NUM> and can thus output sounds.

The second sound circuit board <NUM> may be connected to the main circuit board <NUM> through a second through hole CAH2 of the middle frame <NUM>. As a result, the second sound generating device <NUM> may be connected to a second sound driving unit <NUM> of the main circuit board <NUM>. Accordingly, the second sound generating device <NUM> can vibrate according to an AC voltage from the second sound driving unit <NUM> and can thus output sounds.

The middle frame <NUM> may be disposed below the panel bottom support <NUM>. The middle frame <NUM> may include a synthetic resin, a metal, or both.

A first camera hole CMH1 in which a camera device <NUM> is inserted, a battery hole BH which is for releasing heat from a battery, a first through hole CAH1 that the first sound circuit board <NUM> passes through, the second through hole CAH2 that the second sound circuit board <NUM> passes through, and a third through hole CAH3 that a second connection cable <NUM> connected to the display circuit board <NUM> passes through may be formed in the middle frame <NUM>. Also, a receiving hole AH for accommodating the first and second sound generating devices <NUM> and <NUM> may be formed in the middle frame <NUM>. The width of the receiving hole AH is greater than the width of the first or second sound generating device <NUM> or <NUM>. The receiving hole AH may be formed in one integral body with the battery hole BH.

To minimize or reduce the influence of heat generated by the second sound generating device <NUM> on the display panel <NUM>, the second sound generating device <NUM> may be connected to the first heat dissipation layer and/or the second heat dissipation layer of the panel bottom support <NUM>. In a case where the second sound generating device <NUM> overlaps with the battery hole BH in which a battery may be disposed, it may be difficult to properly release heat from the second sound generating device <NUM> due to the heat from the battery. Thus, the second sound generating device <NUM> may preferably be disposed not to overlap with the battery hole BH.

A waterproof member <NUM> may be disposed along the edges of the middle frame <NUM>. The waterproof member <NUM> may be attached to the top surface of the panel bottom support <NUM> and the bottom surface of the middle frame <NUM>, and as a result, the penetration of moisture or dust between the display panel <NUM> and the middle frame <NUM> can be prevented or reduced by the waterproof member <NUM>. That is, a display device <NUM> that is waterproof and dustproof can be provided.

Specifically, the waterproof member <NUM> may include a base film, a first adhesive film disposed on one surface of the base film, and a second adhesive film disposed on the other surface of the base film. The base film may include PET, PET and a cushion layer, or polyethylene (PE) foam. The first and second adhesive films may be PSAs. The first adhesive film may be attached to the bottom surface of the panel bottom support <NUM>, and the second adhesive film may be attached to the top surface of the middle frame <NUM>.

The main circuit board <NUM> may be disposed below the middle frame <NUM>. The main circuit board <NUM> may be a printed circuit board or a flexible printed circuit board.

The main circuit board <NUM> may include a main processor <NUM>, the camera device <NUM>, a main connector <NUM>, the first sound connector <NUM>, a second sound connector <NUM>, the first sound driving unit <NUM>, and the second sound driving unit <NUM>. The main processor <NUM> and the main connector <NUM> may be disposed on the bottom surface of the main circuit board <NUM> to face the lower cover <NUM>. The camera device <NUM> may be disposed on both the top surface and the bottom surface of the main circuit board <NUM>.

The main processor <NUM> may control all the functions of the display device <NUM>. For example, the main processor <NUM> may output image data to the display driving unit <NUM> of the display circuit board <NUM> so as for the display panel <NUM> to display an image. Also, the main processor <NUM> may receive touch data from the touch driving unit <NUM>, may determine the location of touch input from the user, and may execute an application corresponding to an icon displayed at the location of the touch input. Also, the main processor <NUM> may receive touch data from the touch driving unit <NUM> and may execute an application corresponding to an icon displayed at the location of touch input from the user according to the touch data.

Also, in order to cause the display panel <NUM> to vibrate and generate sounds using the first and second sound generating devices <NUM> and <NUM> in a sound output mode, the main processor <NUM> may output first sound data to the first sound driving unit <NUM> and second sound data to the second sound driving unit <NUM>. Also, in order to cause the display panel <NUM> to vibrate and provide haptic feedback to the user using the second sound generating device <NUM> in a haptic mode, the main processor <NUM> may output haptic data to the second sound driving unit <NUM>.

The main processor <NUM> may be an application processor a central processing unit, or a system chip, which consists of an integrated circuit.

The camera device <NUM> processes image frames provided by an image sensor in a camera mode, such as a still image or a moving image, and outputs or transmits the processed image frames to the main processor <NUM>.

The second connection cable <NUM>, which passes through the third through hole CAH3 of the middle frame <NUM>, may be connected to the main connector <NUM> of the main circuit board <NUM>. As a result, the main circuit board <NUM> can be electrically connected to the display circuit board <NUM> and the touch circuit board <NUM>.

The first sound circuit board <NUM>, which passes through the first through hole CAH1 of the middle frame <NUM>, may be connected to the first sound connector <NUM>, which is disposed on the top surface of the main circuit board <NUM>. The second sound circuit board <NUM>, which passes through the second through hole CAH2 of the middle frame <NUM>, may be connected to the second sound connector <NUM>, which is disposed on the top surface of the main circuit board <NUM>.

The first sound driving unit <NUM> may receive the first sound data from the main processor <NUM>. The first sound driving unit <NUM> may generate the first and second driving voltages based on the first sound data and may provide the first and second driving voltages to the first sound generating device <NUM> via the first sound connector <NUM> and the first sound circuit board <NUM>. Accordingly, the first sound generating device <NUM> can vibrate and thus generate sounds.

The second sound driving unit <NUM> may receive the second sound data or the haptic data from the main processor <NUM>, may generate an AC voltage based on the second sound data or the haptic data, and may provide the AC voltage to the second sound generating device <NUM> via the second sound connector <NUM> or the second sound circuit board <NUM>. Accordingly, the second sound generating device <NUM> can vibrate and can thus output sounds or provide haptic feedback to the user.

Each of the first and second sound driving units <NUM> and <NUM> may include a digital signal processor (DSP) processing a digital signal such as the first sound data or the second sound data, a digital-to-analog converter (DAC) converting the digital signal processed by the DSP into an analog signal, and an amplifier (AMP) amplifying the analog signal provided by the DAC and outputting the amplified analog signal.

A mobile communication module, which can exchange wireless signals with at least one of a base station, an external terminal, and a server via a mobile communication network, may be further provided on the main circuit board <NUM>. The wireless signals may include various types of data associated with the transmission/reception of audio signals, video call signals, or text/multimedia messages.

The lower cover <NUM> may be disposed below the middle frame <NUM> and the main circuit board <NUM>. The lower cover <NUM> may be coupled or fixed to the middle frame <NUM>. The lower cover <NUM> may form the bottom exterior of the display device <NUM>. The lower cover <NUM> may include plastic and/or a metal.

A second camera hole CMH2, through which the camera device <NUM> may be inserted to protrude outwardly, may be formed in the lower cover <NUM>. The location of the camera device <NUM> and the locations of the first and second camera holes CMH1 and CMH2 corresponding to the camera device <NUM> are not limited to what is shown in <FIG>.

According to the exemplary embodiment of <FIG> and <FIG>, the display device <NUM> may provide sounds using the first and second sound generating devices <NUM> and <NUM>, which are disposed below the display panel <NUM>, and may also provide haptic feedback to the user by causing the second sound generating device <NUM> to vibrate or generate vibration. Accordingly, a front speaker can be eliminated from the front of the display device <NUM>, and as a result, the display area at the front of the display device <NUM> can be increased.

In addition, according to the exemplary embodiment of <FIG> and <FIG>, since the first sound generating device <NUM> is formed as a piezoelectric actuator having a high sound pressure level in a high frequency range and the second sound generating device <NUM> is formed as an LRA having a high sound pressure level in a low frequency range, the display device <NUM> can provide the user with sounds having a high sound pressure level in both the low frequency range and the high frequency range.

<FIG> is a bottom view illustrating examples of the cover window <NUM>, the touch circuit board <NUM>, the display panel <NUM>, the display circuit board <NUM>, the panel bottom support <NUM>, the first sound generating device <NUM>, the second sound generating device <NUM>, the first sound circuit board <NUM>, and the second sound circuit board <NUM> of <FIG>. <FIG> is a plan view illustrating examples of the display circuit board <NUM>, the second connection cable <NUM>, the first sound generating device <NUM>, the first sound circuit board <NUM>, the second sound generating device <NUM>, the second sound circuit board <NUM>, and the middle frame <NUM> of <FIG>. <FIG> is a plan view illustrating examples of the second connection cable <NUM>, the first sound circuit board <NUM>, the second sound circuit board <NUM>, and the main circuit board <NUM> of <FIG>.

Hereinafter with reference to <FIG>, <FIG>, and <FIG>, the first sound circuit board <NUM> connected to the first sound generating device <NUM> and connected to the first sound connector <NUM> of the main circuit board <NUM>, the second sound circuit board <NUM> connected to the second sound generating device <NUM> and connected to the second sound connector <NUM> of the main circuit board <NUM>, and the second connection cable <NUM> connected to the display circuit board <NUM> and connected to the main connector <NUM> of the main circuit board <NUM> will be described.

Referring to <FIG>, <FIG>, and <FIG>, one end of the first sound circuit board <NUM> may be connected to the first sound pad area provided at at least one side of the first sound generating device <NUM>. The first sound pad area may include a first pad electrode. A first sound connecting portion <NUM> may be provided at the other end of the first sound circuit board <NUM>. The first sound connecting portion <NUM> of the first sound circuit board <NUM> may be connected to the first sound connector <NUM>, which is disposed on the top surface of the main circuit board <NUM>, through the first through hole CAH1 of the middle frame <NUM>.

One end of the second sound circuit board <NUM> may be connected to the second sound pad area provided at at least one side of the second sound generating device <NUM>. The second sound pad area may include a second pad electrode. A second sound connecting portion <NUM> may be provided at the other end of the second sound circuit board <NUM>. The second sound connecting portion <NUM> of the second sound circuit board <NUM> may be connected to the second sound connector <NUM>, which is disposed on the top surface of the main circuit board <NUM>, through the second through hole CAH2 of the middle frame <NUM>.

The display circuit board <NUM> may include a first circuit board <NUM>, a second circuit board <NUM>, and a first connection cable <NUM>.

The first circuit board <NUM> may be attached to one side of the top or bottom surface of the display panel <NUM> and may be bent toward the bottom surface of the display panel <NUM>. As illustrated in <FIG>, the first circuit board <NUM> may be fixed into fixing holes FH, which are formed in the middle frame <NUM>, by fixing members.

The first circuit board <NUM> may include the display driving unit <NUM> and a first connector 311a. The display driving unit <NUM> and the first connector 311a may be disposed on one surface of the first circuit board <NUM>.

The first connector 311a may be connected to a first end of the first connection cable <NUM> connected to the second circuit board <NUM>. As a result, the display driving unit <NUM> mounted on the first circuit boar <NUM> can be electrically connected to the second circuit board <NUM> via the first connection cable <NUM>.

The second circuit board <NUM> may include the touch connector 312a, a first connection connector 312b, and a second connection connector 312c. The first and second connection connectors 312b and 312c may be disposed on one surface of the second circuit board <NUM>, and the touch connector 312a may be disposed on the other surface of the second circuit board <NUM>.

The touch connector 312a may be connected to the touch connecting portion provided at one end of the touch circuit board <NUM>. As a result, the touch driving unit <NUM> can be electrically connected to the second circuit board <NUM>.

The first connection connector 312b may be connected to a second end of the first connection cable <NUM> connected to the first circuit board <NUM>. As a result, the display driving unit <NUM> mounted on the first circuit board <NUM> can be electrically connected to the second circuit board <NUM> via the first connection cable <NUM>.

The second connection connector 312c may be connected to a first end of the second connection cable <NUM> connected to the main connector <NUM> of the main circuit board <NUM>. As a result, the second circuit board <NUM> can be electrically connected to the main circuit board <NUM> via the second connection cable <NUM>.

A connector connection portion <NUM> may be formed at a second end of the second connection cable <NUM>. As illustrated in <FIG>, the connector connection portion <NUM> of the second connection cable <NUM> may extend to the bottom of the middle frame <NUM> through the third through hole CAH3 of the middle frame <NUM>. Also, as illustrated in <FIG>, the connector connecting portion <NUM> of the second connection cable <NUM> passing through the third through hole CAH3 may extend to the bottom of the main circuit board <NUM> through the gap between the middle frame <NUM> and the main circuit board <NUM>. Finally, as illustrated in <FIG>, the connector connecting portion <NUM> of the second connection cable <NUM> may be connected to the main connector <NUM>, which is disposed on the bottom surface of the main circuit board <NUM>.

According to the exemplary embodiment of <FIG>, <FIG>, and <FIG>, the first sound circuit board <NUM>, which is connected to the first sound generating device <NUM>, may be connected to the first sound connector <NUM> of the main circuit board <NUM> through the first through hole CAH1 of the middle frame <NUM>, and the second sound circuit board <NUM>, which is connected to the second sound generating device <NUM>, may be connected to the second sound connector <NUM> of the main circuit board <NUM> through the second through hole CAH2 of the middle frame <NUM>. Accordingly, the first sound generating device <NUM> and the first sound driving unit <NUM> of the main circuit board <NUM> can be stably connected, and the second sound generating device <NUM> and the second sound driving unit <NUM> of the main circuit board <NUM> can be stably connected.

In addition, according to the exemplary embodiment of <FIG>, <FIG>, and <FIG>, the second connection cable <NUM>, which is connected to the display circuit board <NUM>, may extend to the bottom of the middle frame <NUM> through the third through hole CAH3 of the middle frame <NUM> and may thus be connected to the main connector <NUM> of the main circuit board <NUM>. Accordingly, the display circuit board <NUM> and the main circuit board <NUM> can be stably connected.

<FIG> is an exemplary cross-sectional view taken along a sectional line I-I' of <FIG>, <FIG>, and <FIG>.

The cover window <NUM>, the touch sensing device <NUM>, the display panel <NUM>, the panel bottom support <NUM>, the first adhesive member <NUM>, the second adhesive member <NUM>, and the third adhesive member <NUM> have already been described in detail with reference to <FIG> and <FIG>, and thus, detailed descriptions thereof will be omitted to avoid redundancy.

Referring to <FIG>, the first sound generating device <NUM> is disposed below the panel bottom support <NUM>. The first sound generating device <NUM> may be attached to the bottom surface of the panel bottom support <NUM> via the fourth adhesive member <NUM>. The fourth adhesive member <NUM> may be a PSA.

A first pad electrode 510a of the first sound generating device <NUM> may be disposed to protrude from at least one side of the first sound generating device <NUM>. The first pad electrode 510a of the first sound generating device <NUM> may be connected to one end of the first sound circuit board <NUM>. <FIG> illustrates the top surface of the first sound circuit board <NUM> as being connected to the bottom surface of the first pad electrode 510a, but the exemplary embodiments are not limited thereto. The bottom surface of the first sound circuit board <NUM> may be connected to the top surface of the first pad electrode 510a. The other end of the first sound circuit board <NUM> may be connected to the first sound connector <NUM>, which is disposed on the top surface of the main circuit board <NUM>, through the first through hole CAH1, which penetrates the middle frame <NUM>.

The second sound generating device <NUM> is disposed to overlap with the first sound generating device <NUM>. The second sound generating device <NUM> may be disposed below the first sound generating device <NUM>. The second sound generating device <NUM> may be attached to the bottom surface of the first sound generating device <NUM> via the fifth adhesive member <NUM>. The fifth adhesive member <NUM> may be a PSA.

A second pad electrode 520a of the second sound generating device <NUM> may be disposed to protrude from one side of the second sound generating device <NUM>. The second pad electrode 520a of the second sound generating device <NUM> may be connected to one end of the second sound circuit board <NUM>. <FIG> illustrates the bottom surface of the second sound circuit board <NUM> as being connected to the top surface of the second pad electrode 520a, but the exemplary embodiments are not limited thereto. The top surface of the second sound circuit board <NUM> may be connected to the bottom surface of the second pad electrode 520a. The other end of the second sound circuit board <NUM> may be connected to the second sound connector <NUM>, which is disposed on the top surface of the main circuit board <NUM>, through the second through hole CAH2, which penetrates the middle frame <NUM>.

The first and second sound generating devices <NUM> and <NUM> may be disposed in the receiving hole AH, which penetrates the middle frame <NUM>. If the first and second sound generating devices <NUM> and <NUM> are not tall, a receiving groove, instead of the receiving hole AH, may be formed in the middle frame <NUM>.

The first and second sound generating devices <NUM> and <NUM> may vibrate in a vertical direction (or the Z-axis direction). The first sound generating device <NUM> may vibrate in the vertical direction (or the Z-axis direction), and the second sound generating device <NUM> may vibrate in a horizontal direction (or the X- or Y-axis direction).

<FIG> is a perspective view of an example of the first sound generating device <NUM> of <FIG>. <FIG> is a plan view of the first sound generating device <NUM> of <FIG>. <FIG> is a cross-sectional view taken along a sectional line II-II' of <FIG>.

The first sound generating device <NUM> will hereinafter be described with reference to <FIG>, <FIG>, and <FIG>.

Referring to <FIG>, <FIG>, and <FIG>, the first sound generating device <NUM> may include a vibration layer <NUM>, a first electrode <NUM>, a second electrode <NUM>, a first pad electrode 512a, and a second pad electrode 513a.

The first electrode <NUM> may include a first stem electrode <NUM> and first branch electrodes <NUM>. The first stem electrode <NUM> may be disposed on one side of the vibration layer <NUM>. The first stem electrode <NUM> may be disposed on more than one side of the vibration layer <NUM>. The first stem electrode <NUM> may be disposed on the top surface of the vibration layer <NUM>. The first branch electrodes <NUM> may be branched off from the first stem electrode <NUM>. The first branch electrodes <NUM> may be disposed in parallel to one another.

The second electrode <NUM> may include a second stem electrode <NUM> and second branch electrodes <NUM>. The second stem electrode <NUM> may be disposed on another side of the vibration layer <NUM>. The second stem electrode <NUM> may be disposed on more than one side of the vibration layer <NUM> where the first stem electrode <NUM> is not disposed. The second stem electrode <NUM> may be disposed on the top surface of the vibration layer <NUM>. The first and second stem electrodes <NUM> and <NUM> are spaced from each other. The second branch electrodes <NUM> may be branched off from the second stem electrode <NUM>. The second branch electrodes <NUM> may be disposed in parallel to one another.

The first branch electrodes <NUM> and the second branch electrodes <NUM> may be disposed substantially parallel to one another in the horizontal direction (or the X- or Y-axis direction). The first branch electrodes <NUM> and the second branch electrodes <NUM> may be alternately disposed in the vertical direction (or the Z-axis direction). That is, the first branch electrodes <NUM> and the second branch electrodes <NUM> may be disposed repeatedly in the order of a first branch electrode <NUM>, a second branch electrode <NUM>, a first branch electrode <NUM>, and a second branch electrode <NUM> along the vertical direction (or the Z-axis direction).

The first pad electrode 512a may be connected to the first electrode <NUM>. The first pad electrode 512a may protrude outwardly from the first stem electrode <NUM>, which is disposed on one side of the vibration layer <NUM>.

The second pad electrode 513a may be connected to the second electrode <NUM>. The second pad electrode 513a may protrude outwardly from the second stem electrode <NUM>, which is disposed on the other side of the vibration layer <NUM>.

The first and second pad electrodes 512a and 513a may be connected to lead lines or pad electrodes of a first sound circuit board <NUM>. The lead lines or the pad electrodes of the first sound circuit board <NUM> may be disposed on the bottom surface of the first sound circuit board <NUM>.

In a case where the first and second pad electrodes 512a and 513a protrude outwardly from different sides of the vibration layer <NUM>, as illustrated in <FIG>, the first sound circuit board <NUM> may be disposed on a side, other than a first side, of the first sound generating device <NUM>, but the exemplary embodiments are not limited thereto. The first and second pad electrodes 512a and 513a may protrude outwardly from the same side of the vibration layer <NUM>, in which case, the first sound circuit board <NUM> may be disposed on the first side of the first sound generating device <NUM>.

Since the vibration layer <NUM> is fabricated at high temperature, the first and second electrodes <NUM> and <NUM> may be formed of a metal with a high melting point such as Ag or an alloy of Ag and Pd. In a case where the first and second electrodes <NUM> and <NUM> are formed of an alloy of Ag and Pd, the content of Ag in each of the first and second electrodes <NUM> and <NUM> may be greater than the content of Pd in each of the first and second electrodes <NUM> and <NUM>.

The vibration layer <NUM> may be a piezoelectric actuator that is deformed by first and second driving voltages applied to the first and second electrodes <NUM> and <NUM>, respectively. In this case, the vibration layer <NUM> may be one of a piezoelectric material such as a polyvinylidene difluoride (PVDF) film or lead zirconate titanate (PZT) and an electroactive polymer.

The vibration layer <NUM> may be disposed between the first branch electrodes <NUM> and the second branch electrodes <NUM>. The vibration layer <NUM> contracts or expands depending on the difference between the first driving voltage applied to the first branch electrodes <NUM> and the second driving voltage applied to the second branch electrodes <NUM>.

Specifically, as illustrated in <FIG>, the polarity of the vibration layer <NUM> between the first branch electrodes <NUM> and their respective underlying second branch electrodes <NUM> may have an upward direction (illustrated as ↑). In this case, the vibration layer <NUM> may have a positive polarity in upper parts thereof adjacent to the first branch electrodes <NUM> and a negative polarity in lower parts thereof adjacent to the second branch electrodes <NUM>. Also, the polarity of the vibration layer <NUM> between the second branch electrodes <NUM> and their respective underlying first branch electrodes <NUM> may have a downward direction (illustrated as ↓). In this case, the vibration layer <NUM> may have a negative polarity in the upper parts thereof adjacent to the first branch electrodes <NUM> and a positive polarity in the lower parts thereof adjacent to the second branch electrodes <NUM>. The direction of the polarity of the vibration layer <NUM> may be determined by a poling process for applying an electric field to the vibration layer <NUM> using the first branch electrodes <NUM> and the second branch electrodes <NUM>.

<FIG> is a schematic view illustrating how a vibration layer disposed between first and second branch electrodes <NUM> and <NUM> of the first sound generating device <NUM> vibrates. <FIG> and <FIG> are schematic views illustrating how the display panel <NUM> vibrates in response to the vibration of the first sound generating device <NUM>.

When the direction of the polarity of the vibration layer <NUM> between the first branch electrodes <NUM> and their respective underlying second branch electrodes <NUM> is the upward direction (↑), as illustrated in <FIG>, the vibration layer <NUM> may contract in accordance with a first force F1 in response to a positive first driving voltage and a negative second driving voltage being applied to the first branch electrodes <NUM> and the second branch electrodes <NUM>, respectively. The first force F1 may be a contraction force. On the other hand, in response to a negative first driving voltage and a positive second driving voltage being applied to the first branch electrodes <NUM> and the second branch electrodes <NUM>, respectively, the vibration layer <NUM> may expand in accordance with a second force F2. The second force F2 may be an extension force.

When the direction of the polarity of the vibration layer <NUM> between the second branch electrodes <NUM> and their respective underlying first branch electrodes <NUM> is the downward direction (↓), the vibration layer <NUM> may expand in accordance with an extension force in response to a positive first driving voltage and a negative second driving voltage being applied to the first branch electrodes <NUM> and the second branch electrodes <NUM>, respectively. On the other hand, in response to a negative first driving voltage and a positive second driving voltage being applied to the first branch electrodes <NUM> and the second branch electrodes <NUM>, respectively, the vibration layer <NUM> may contract in accordance with a contraction force. The second force F2 may be an extension force.

According to the exemplary embodiment of <FIG>, in a case where the first and second driving voltages applied to the first and second electrodes <NUM> and <NUM>, respectively, alternately change from a positive polarity to a negative polarity, the vibration layer <NUM> repeatedly contracts and expands. As a result, the first sound generating device <NUM> vibrates.

The first sound generating device <NUM> is disposed on the bottom surface of the display panel <NUM>. Thus, as the vibration layer <NUM> of the first sound generating device <NUM> contracts and expands, the display panel <NUM> vibrates vertically due to stress, as illustrated in <FIG> and <FIG>. Since the display panel <NUM> is caused by the first sound generating device <NUM> to vibrate, the display device <NUM> can output sounds.

The second sound generating device <NUM> may be substantially the same as the first sound generating device <NUM> described above with reference to <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, and <FIG>, and thus, a detailed description thereof will be omitted to avoid redundancy.

<FIG> is a perspective view of another example of the first sound generating device of <FIG>. <FIG> is a plan view of the first sound generating device of <FIG>. <FIG> is a cross-sectional view taken along a sectional line III-III' of <FIG>.

The exemplary embodiment of <FIG>, <FIG>, and <FIG> differs from the exemplary embodiment of <FIG>, <FIG>, and <FIG> in that a first stem electrode <NUM> of a first electrode <NUM> is disposed in a first contact hole CH1 penetrating a vibration layer <NUM> and a second stem electrode <NUM> of a second electrode <NUM> is disposed in a second contact hole CH2 penetrating the vibration layer <NUM>. The exemplary embodiment of <FIG>, <FIG>, and <FIG> will hereinafter be described focusing mainly on the differences with the exemplary embodiment of <FIG>, <FIG>, and <FIG>.

Referring to <FIG>, <FIG>, and <FIG>, the first contact hole CH1 is formed to penetrate the vibration layer <NUM>, and the first stem electrode <NUM> is disposed in the first contact hole CH1. The first stem electrode <NUM> is arranged in a vertical direction (or a Z-axis direction), and second branch electrodes <NUM> are arranged in a horizontal direction (or an X- or Y-axis direction). Since the vibration layer <NUM> cannot vibrate if the first stem electrode <NUM> and the second branch electrodes <NUM> are connected, the second branch electrodes <NUM> are disposed to avoid the first stem electrode <NUM> and thus not to be connected to the first stem electrode <NUM>.

The second contact hole CH2 is formed to penetrate the vibration layer <NUM>, and the second stem electrode <NUM> is disposed in the second contact hole CH2. The second stem electrode <NUM> is arranged in the vertical direction (or the Z-axis direction), and first branch electrodes <NUM> are arranged in the horizontal direction (or the X- or Y-axis direction). Since the vibration layer <NUM> cannot vibrate if the second stem electrode <NUM> and the first branch electrodes <NUM> are connected, the first branch electrodes <NUM> are disposed to avoid the second stem electrode <NUM> and thus not to be connected to the second stem electrode <NUM>.

A first pad electrode 512a may be connected to the first electrode <NUM>. The first pad electrode 512a may protrude outwardly from the first stem electrode <NUM>, which is disposed on one side of the vibration layer <NUM>.

A second pad electrode 513a may be connected to the second electrode <NUM>. The second pad electrode 513a may protrude outwardly from the second stem electrode <NUM>, which is disposed on another side of the vibration layer <NUM>.

The first and second pad electrodes 512a and 513a may be connected to lead lines or pad electrodes of the first sound circuit board <NUM>. The lead lines or the pad electrodes of the first sound circuit board <NUM> may be disposed on the bottom surface of the first sound circuit board <NUM>.

The second sound generating device <NUM> may be substantially the same as the first sound generating device <NUM> described above with reference to <FIG>, <FIG>, and thus, a detailed description thereof will be omitted to avoid redundancy.

<FIG> is another exemplary cross-sectional view taken along the sectional line I-I' of <FIG>, <FIG>, and <FIG>.

The exemplary embodiment of <FIG> differs from the exemplary embodiment of <FIG> in that a connecting member <NUM> is further provided to connect one side of the first sound generating device <NUM> and one side of the second sound generating device <NUM>. The exemplary embodiment of <FIG> will hereinafter be described focusing mainly on the difference with the exemplary embodiment of <FIG>.

Referring to <FIG>, the connecting member <NUM> is disposed on a first side of the first sound generating device <NUM> and on a first side of the second sound generating device <NUM>. The connecting member <NUM> may be attached to the first sides of the first and second sound generating devices <NUM> and <NUM> via an adhesive member. The connecting member <NUM> may be coupled to the first sides of the first and second sound generating devices <NUM> and <NUM> via a coupling member. The connecting member <NUM> may be attached to the first side of one of the first and second sound generating devices <NUM> and <NUM> via an adhesive member and may be coupled to the first side of the other sound generating device via a coupling member. Here, the adhesive member may be a PSA, and the coupling member may be a screw. The connecting member <NUM> may also be formed in one integral body with the second sound generating device <NUM>.

<FIG> illustrates the connecting member <NUM> as connecting the first sides of the first and second sound generating devices <NUM> and <NUM>, but the exemplary embodiments are not limited thereto. If the width, in the first direction (or the X-axis direction), of the first sound generating device <NUM> and the width, in the first direction (or the X-axis direction), of the second sound generating device <NUM> are substantially the same, the connecting member <NUM> may connect a side opposite to the first side of the first sound generating device <NUM> and a side opposite to the first side of the second sound generating device <NUM>. If the width, in the second direction (or the Y-axis direction), of the first sound generating device <NUM> and the width, in the second direction (or the Y-axis direction), of the second sound generating device <NUM> are substantially the same, the connecting member <NUM> may connect a side not opposite to the first side of the first sound generating device <NUM> and a side not opposite to the first side of the second sound generating device <NUM>.

According to the exemplary embodiment of <FIG>, since the connecting member <NUM> connects at least one side of the first sound generating device <NUM> and at least one side of the second sound generating device <NUM>, the first sound generating device <NUM> can vibrate along with the second sound generating device <NUM> when the second sound generating device <NUM> vibrates to provide haptic feedback to the user. Accordingly, the intensity of vibration can be raised.

The exemplary embodiment of <FIG> differs from the exemplary embodiment of <FIG> in that the height of the second sound generating device <NUM> is smaller than the height of the first sound generating device <NUM>, and that the width, in the first direction (or the X-axis direction), of the second sound generating device <NUM> is greater than the width, in the first direction (or the X-axis direction), of the first sound generating device <NUM>. The exemplary embodiment of <FIG> will hereinafter be described focusing mainly on the differences with the exemplary embodiment of <FIG>.

Referring to <FIG>, the first sound generating device <NUM> may vibrate in the vertical direction (or the Z-axis direction), and the second sound generating device <NUM> may vibrate in the horizontal direction (or the X- or Y-axis direction). When the second sound generating device <NUM> vibrates in the horizontal direction (or the X- or Y-axis direction), the voice coil, the mass body, and the spring of the second sound generating device <NUM> may be aligned in the horizontal direction (or the X- or Y-axis direction), and as a result, the width, in the first direction (or the X-axis direction) or the second direction (or the Y-axis direction), of the second sound generating device <NUM> may be greater than the width, in the first direction (or the X-axis direction) or the second direction (or the Y-axis direction), of the first sound generating device <NUM>. Also, the height of the second sound generating device <NUM> may be smaller than the height of the first sound generating device <NUM>. The height of the first sound generating device <NUM> refers to the length, in the third direction (or the Z-axis direction), of the first sound generating device <NUM>, and the height of the second sound generating device <NUM> refers to the length, in the third direction (or the Z-axis direction), of the second sound generating device <NUM>.

The exemplary embodiment of <FIG> differs from the exemplary embodiment of <FIG> in that the height of the second sound generating device <NUM> is greater than the height of the first sound generating device <NUM>, and that the width, in the first direction (or the X-axis direction), of the second sound generating device <NUM> is smaller than the width, in the first direction (or the X-axis direction), of the first sound generating device <NUM>. The exemplary embodiment of <FIG> will hereinafter be described focusing mainly on the differences with the exemplary embodiment of <FIG>.

Referring to <FIG>, the first and second sound generating devices <NUM> and <NUM> may both vibrate in the vertical direction (or the Z-axis direction). When the second sound generating device <NUM> vibrates in the vertical direction (or the Z-axis direction), the voice coil, the mass body, and the spring of the second sound generating device <NUM> may be aligned in the vertical direction (or the Z-axis direction), and as a result, the height of the second sound generating device <NUM> may be greater than the height of the first sound generating device <NUM>. The height of the first sound generating device <NUM> refers to the length, in the third direction (or the Z-axis direction), of the first sound generating device <NUM>, and the height of the second sound generating device <NUM> refers to the length, in the third direction (or the Z-axis direction), of the second sound generating device <NUM>. Also, the width, in the first direction (or the X-axis direction) or the second direction (or the Y-axis direction), of the second sound generating device <NUM> may be smaller than the width, in the first direction (or the X-axis direction) or the second direction (or the Y-axis direction), of the first sound generating device <NUM>.

The exemplary embodiment of <FIG> differs from the exemplary embodiment of <FIG> in that the first sound generating device <NUM> is disposed below the second sound generating device <NUM>. The exemplary embodiment of <FIG> will hereinafter be described focusing mainly on the difference with the exemplary embodiment of <FIG>.

Referring to <FIG>, the second sound generating device <NUM> may be disposed below the panel bottom support <NUM>, and the first sound generating device <NUM> may be disposed below the second sound generating device <NUM>. In this case, the second sound generating device <NUM> may be attached to the bottom surface of the panel bottom support <NUM> via the fourth adhesive member <NUM>, and the first sound generating device <NUM> may be attached to the bottom surface of the second sound generating device <NUM> via the fifth adhesive member <NUM>. The fourth and fifth adhesive members <NUM> and <NUM> may be PSAs.

<FIG> illustrates the first and second sound generating devices <NUM> and <NUM> as having the same width in the first direction (or the X-axis direction) and having the same height, but the exemplary embodiments are not limited thereto. That is, when the second sound generating device <NUM> vibrates in the horizontal direction (or the X- or Y-axis direction), as illustrated in <FIG>, the height of the second sound generating device <NUM> may be smaller than the height of the first so und generating device <NUM>, and the width, in the first direction (or the X-axis direction), of the second sound generating device <NUM> may be greater than the width, in the first direction (or the X-axis direction), of the first sound generating device <NUM>. When the second sound generating device <NUM> vibrates in the vertical direction (or the Z-axis direction), as illustrated in <FIG>, the height of the second sound generating device <NUM> may be greater than the height of the first so und generating device <NUM>, and the width, in the first direction (or the X-axis direction), of the second sound generating device <NUM> may be smaller than the width, in the first direction (or the X-axis direction), of the first sound generating device <NUM>.

According to the exemplary embodiment of <FIG>, the display device <NUM> not only can provide sounds using the first and second sound generating devices <NUM> and <NUM>, which are disposed below the display panel <NUM>, but also can provide haptic feedback to the user by causing the second sound generating device <NUM> to vibrate. Accordingly, a front speaker can be eliminated from the front of the display device <NUM>, and as a result, the display area at the front of the display device <NUM> can be increased.

In addition, according to the exemplary embodiment of <FIG>, since the first sound generating device <NUM> is formed as a piezoelectric actuator having a high sound pressure level in a high frequency range and the second sound generating device <NUM> is formed as an LRA having a high sound pressure level in a low frequency range, the display device <NUM> can provide the user with sounds having a high sound pressure level in both the low frequency range and the high frequency range.

<FIG> show embodiments that do not form part of the invention. <FIG> is a bottom view illustrating another example of the cover window <NUM>, the touch circuit board <NUM>, the display panel <NUM>, the display circuit board <NUM>, the panel bottom support <NUM>, the first sound generating device <NUM>, the second sound generating device <NUM>, the first sound circuit board <NUM>, and the second sound circuit board <NUM> of <FIG>. <FIG> is a plan view illustrating other examples of the display circuit board <NUM>, the second connection cable <NUM>, the first sound generating device <NUM>, the first sound circuit board <NUM>, the second sound generating device <NUM>, the second sound circuit board <NUM>, and the middle frame of <FIG>. <FIG> is another exemplary cross-sectional view taken along the sectional line I-I' of <FIG>, <FIG>, and <FIG>.

The exemplary embodiment of <FIG>, <FIG>, and <FIG> differs from the exemplary embodiment of <FIG>, <FIG>, and <FIG> in that the first and second sound generating devices <NUM> and <NUM> do not overlap with each other. Thus, the exemplary embodiment of <FIG>, <FIG>, and <FIG> will hereinafter be described focusing mainly on the difference with the exemplary embodiment of <FIG>, <FIG>, and <FIG>.

Referring to <FIG>, <FIG>, and <FIG>, the first and second sound generating devices <NUM> and <NUM> may be disposed below the panel bottom support <NUM>.

The first and second sound generating devices <NUM> and <NUM> may be attached to the bottom surface of the panel bottom support <NUM>. In this case, the first and second sound generating devices <NUM> and <NUM> may be attached to the bottom surface of the panel bottom support <NUM> via the fourth adhesive member <NUM>. The fourth adhesive member <NUM> may be a PSA.

According to the exemplary embodiment of <FIG>, <FIG>, and <FIG>, the display device <NUM> not only can provide sounds using the first and second sound generating devices <NUM> and <NUM>, which are disposed below the display panel <NUM>, but also can provide haptic feedback to the user by causing the second sound generating device <NUM> to vibrate. Accordingly, a front speaker can be eliminated from the front of the display device <NUM>, and as a result, the display area at the front of the display device <NUM> can be increased.

In addition, according to the exemplary embodiment of <FIG>, <FIG>, and <FIG>, since the first sound generating device <NUM> is formed as a piezoelectric actuator having a high sound pressure level in a high frequency range and the second sound generating device <NUM> is formed as an LRA having a high sound pressure level in a low frequency range, the display device <NUM> can provide the user with sounds having a high sound pressure level in both the low frequency range and the high frequency range.

<FIG> is a flowchart illustrating a method of driving sound generating devices in a display device according to an exemplary embodiment of the invention.

Referring to <FIG>, the main processor <NUM> determines whether the display device <NUM> is being driven in the sound output mode (S101). The sound output mode is a mode in which the display device <NUM> outputs or generates sounds by executing an application such as a music or video player application. Also, the sound output mode is a mode in which the user performs a voice or video call via the display device <NUM> by using the mobile communication module of the main circuit board <NUM>.

Thereafter, the main processor <NUM> controls the display device <NUM> to output sounds in the sound output mode (S102) by using both the first and second sound generating devices <NUM> and <NUM> to cause the display panel <NUM> to vibrate.

Specifically, in the sound output mode, the main processor <NUM> outputs or transmits the first sound data to the first sound driving unit <NUM> and the second sound data to the second sound driving unit <NUM>. The first sound driving unit <NUM> generates the first and second driving voltages based on the first sound data. The first sound driving unit <NUM> outputs or transmits the first and second driving voltages to the first and second electrodes <NUM> and <NUM> of the first sound generating device <NUM> via the first sound connector <NUM> and the first sound circuit board <NUM>. The second sound driving unit <NUM> generates an AC voltage based on the second sound data. The second sound driving unit <NUM> outputs or transmits the AC voltage to the second sound generating device <NUM> via the second sound connector <NUM> and the second sound circuit board <NUM>.

The first sound generating device <NUM> vibrates in accordance with the first and second driving voltages, and the second sound generating device <NUM> vibrates in accordance with the AC voltage. The display panel <NUM> vibrates vertically in accordance with the vibration of the first and second sound generating devices <NUM> and <NUM>, and as a result, the display device <NUM> can output sounds.

Specifically, since the first sound generating device <NUM> is formed as a piezoelectric actuator, sounds output by the first sound generating device <NUM> may have a frequency F0 of <NUM>, as illustrated in <FIG>. That is, sounds output by the first sound generating device <NUM> may have a high sound pressure level in a high frequency range HFR.

Since the second sound generating device <NUM> is formed as an LRA, sounds output by the second sound generating device <NUM> may have a frequency F0 of <NUM>, as illustrated in <FIG>. That is, sounds output by the second sound generating device <NUM> may have a high sound pressure level in a low frequency range LFR.

Accordingly, sounds output by the first and second sound generating devices <NUM> and <NUM> may have a high sound pressure level in both the low frequency range LFR and the high frequency range HFR, as illustrated in <FIG>. That is, the display device <NUM> can provide high-quality sounds to the user.

<FIG> are graphs showing the sound pressures of sounds generated by the first and second sound generating devices <NUM> and <NUM>. Referring to <FIG>, the X axis represents the vibration frequency of the display panel <NUM>, which is caused by the first and second sound generating devices <NUM> and <NUM> to vibrate, the Y axis represents sound pressure level (SPL), and F0 denotes the minimum frequency at which the vibration displacement of the display panel <NUM> exceeds a reference level. The low frequency range LFR is a range where the vibration frequency of the display panel <NUM> is <NUM> or lower, and the high frequency range HFR is a range where the vibration frequency of the display panel <NUM> is higher than <NUM>.

Referring again to <FIG>, if the display device <NUM> is not being driven in the sound output mode, the main processor <NUM> determines whether the display device <NUM> is being driven in the haptic mode (S103). The haptic mode is a mode for providing haptic feedback to the user by causing the display device <NUM> to vibrate.

Thereafter, the main processor <NUM> causes the display panel <NUM> to vibrate by using the second sound generating device <NUM> in the haptic mode and thus controls the display device <NUM> to provide haptic feedback to the user (S104).

The main processor <NUM> outputs or transmits haptic data to the second sound driving unit <NUM> in the haptic mode. The second sound driving unit <NUM> generates an AC voltage based on the haptic data. The second sound driving unit <NUM> outputs or transmits the AC voltage to the second sound generating device <NUM> via the second sound connector <NUM> and the second sound circuit board <NUM>.

The second sound generating device <NUM> vibrates in accordance with the AC voltage. The display panel <NUM> vibrates in accordance with the vibration of the second sound generating device <NUM>, and as a result, haptic feedback can be provided to the user. The second sound generating device <NUM> can vibrate at a higher vibration displacement (or amplitude) in a relatively narrower frequency range in the haptic mode than in the sound output mode.

Claim 1:
A display device (<NUM>) comprising:
a display panel (<NUM>); and
first and second sound generating devices (<NUM>, <NUM>) configured to generating sounds and vibrate the display panel (<NUM>),
wherein the first sound generating device (<NUM>) has a higher sound pressure level than the second sound generating device (<NUM>) in a first frequency range, and the second sound generating device (<NUM>) has a higher sound pressure level than the first sound generating device (<NUM>) in a second frequency range lower than the first frequency range, and
wherein the first sound generating device (<NUM>) and the second sound generating device (<NUM>) at least partially overlap each other in a thickness direction of the display panel (<NUM>), and characterized in that
the first sound generating device (<NUM>) includes a piezoelectric actuator, and the second sound generating device (<NUM>) includes an actuator by pressing a mass connected to a spring via a voice coil.