Patent Description:
With the development of information-oriented society, demands for display devices for displaying images are increasing in various forms. For example, display devices are used for various electronic appliances such as smart phones, tablet PCs, digital cameras, notebook computers, navigators, and televisions. The display device includes a display panel for displaying an image and a sound generator for providing a sound.

When the display device is implemented as a smart phone, a user may make a call by making his ear contact the display device in a call mode, or may make a call without making contact in the call mode. Further, in the call mode, pressure to allow the ear to press the display device is different for each user. However, the sound pressure level of a sound provided by the sound generator with respect to a wavelength may change depending on the position of the user's ear, for example, whether the user's ear contacts the display device in the call mode and the pressure to allow the user's ear to press the display device. Therefore, in order to provide high-quality sound to the user in the call mode, it is required to adjust the sound pressure level of a sound with respect to a wavelength depending on whether the user's ear contact the display device in the call mode and the pressure to allow the user's ear to press the display device.

<CIT> discloses a display device with the features as summarized in the preamble of claim <NUM>. Reference is made also to <CIT>, <CIT>, and <CIT>.

The invention is defined by the features of claim <NUM>. The dependent claims describe preferred embodiments. Devices constructed according to the invention are capable of providing a display device which can provide a high-quality sound by maintaining the sound pressure level of a sound uniform in a low-frequency range, a middle-frequency range, and a high-frequency range depending on different locations of a user's ear, for example, contacting the front surface of the display device and/or the pressure of the user's ear pressing the display device.

According to the invention, a display device includes: a display panel configured to display an image; a touch sensing device configured to sense a touch of an object; a sound driver configured to generate and transmit a first sound driving signal and a second sound driving signal according to first sound data and second sound data; and a sound generator configured to generate a sound according to the first sound driving signal and the second sound driving signal, such that a sound pressure level in a first frequency range is between a first sound pressure level and a second sound pressure level in a first operating mode and a second operating mode, wherein the display device is in the first operating mode in response to the touch sensing device not sensing the touch of the object, and the display device is in the second operating mode in response to the touch sensing device sensing the touch of the object. Further features of the invention can be derived from claim <NUM>.

The touch sensing device may be disposed on a first surface of the display panel, and the sound generator may be disposed on a second surface of the display panel, opposite to the first surface.

The display device may further include a pressure sensing device configured to sense a pressure of the object, the display device may be in the second operating mode in response to the pressure sensing device sensing the pressure of the object being equal to or lower than a first pressure, and the display device may be in a third operating mode in response to the pressure sensing device sensing the pressure of the object being higher than the first pressure and may be equal to or lower than a second pressure.

The touch sensing device may be disposed on a first surface of the display panel, the sound generator may be disposed on a second surface of the display panel, opposite to the first surface, and the pressure sensing device may be disposed on the second surface of the display panel except for a region where the sound generator may be disposed.

The sound driver may further include: a digital-analog converter configured to convert the first sound data and the second sound data modulated by the digital signal processor into a first driving voltage and a second driving voltage, which are analog signals; and an amplifier configured to amplify and transmit the first driving voltage and the second driving voltage.

Further, an X-axis, a Y-axis, and a Z-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. For example, the X-axis, the Y-axis, and the Z-axis may be perpendicular to one another, or may represent different directions that are not perpendicular to one another.

As is customary in the field, some exemplary embodiments are described and illustrated in the accompanying drawings in terms of functional blocks, units, and/or modules. Those skilled in the art will appreciate that these blocks, units, and/or modules are physically implemented by electronic (or optical) circuits, such as logic circuits, discrete components, microprocessors, hard-wired circuits, memory elements, wiring connections, and the like, which may be formed using semiconductor-based fabrication techniques or other manufacturing technologies. In the case of the blocks, units, and/or modules being implemented by microprocessors or other similar hardware, they may be programmed and controlled using software (e.g., microcode) to perform various functions discussed herein and may optionally be driven by firmware and/or software. It is also contemplated that each block, unit, and/or module may be implemented by dedicated hardware, or as a combination of dedicated hardware to perform some functions and a processor (e.g., one or more programmed microprocessors and associated circuitry) to perform other functions. Also, each block, unit, and/or module of some exemplary embodiments may be physically separated into two or more interacting and discrete blocks, units, and/or modules without departing from the scope of the inventive concepts. Further, the blocks, units, and/or modules of some exemplary embodiments may be physically combined into more complex blocks, units, and/or modules without departing from the scope of the inventive concepts.

<FIG> is a perspective view of a display device <NUM> according to an exemplary embodiment. <FIG> is an exploded perspective view of a display device according to an exemplary embodiment. <FIG> is a back view showing a panel lower support, a first sound generator, a sound circuit board, a display circuit board, and a touch circuit board in the display device of <FIG>. <FIG> is a cross-sectional view taken along a sectional line I-I' of <FIG>. <FIG> is a cross-sectional view showing the display area of the display panel of <FIG>. <FIG> is an enlarged cross-sectional view of the region A in <FIG>. <FIG> is a plan view showing the first sound generator of <FIG>. <FIG> is a cross-sectional view taken along a sectional line II-II' of <FIG>. <FIG> is an schematic view illustrating exemplary vibration of the first sound generator.

<FIG> and <FIG> illustrate that the display device according to an exemplary embodiment is a portable terminal. The portable terminal may include a smart phone, a tablet PC, a personal digital assistant (PDA), a portable multimedia player (PMP), a game machine, and a wristwatch type electronic appliance. However, the display device according to an exemplary embodiment is not limited to the portable terminal, and may be used for small and middle electronic appliances such as a monitor, a notebook computer, a car navigator, and a camera as well as large electronic appliances such as a television and an outside billboard.

Referring to <FIG> and <FIG>, a display device <NUM> according to an exemplary embodiment includes a cover window <NUM>, a touch sensing device <NUM>, a touch circuit board <NUM>, a display panel <NUM>, a display circuit board <NUM>, a panel lower support <NUM>, a first sound generator <NUM>, a sound circuit board <NUM>, a pressure sensing device <NUM>, a lower bracket <NUM>, a main circuit board <NUM>, and a lower cover <NUM>.

In this specification, the "on", "over", "top", "upper side", or "upper surface" refers to a direction in which the cover window <NUM> is disposed, that is, a Z-axis direction, with respect to the display panel <NUM>, and the "beneath", "under", "bottom", "lower side", or "lower surface" refers to a direction in which the panel lower support <NUM> is disposed, that is, a direction opposite to the Z-axis direction, with respect to the display panel <NUM>.

The display device <NUM> may have a rectangular shape in a plan view. For example, as shown in <FIG>, the display device <NUM> may have a rectangular planar shape having short sides in the first direction (X-axis direction) and long sides in the second direction (Y-axis direction). The edge where the short side in the first direction (X-axis direction) meets the long side in the second direction (Y-axis direction) may be formed to have a round shape of a predetermined curvature or have a right angle shape as shown in <FIG>. The planar shape of the display device <NUM> is not limited to a rectangular shape, and may be formed in another polygonal shape, circular shape, or elliptical shape.

The cover window <NUM> may be disposed on the display panel <NUM> so as to cover the upper surface of the display panel <NUM>. Thus, the cover window <NUM> may function to protect the upper surface of the display panel <NUM>. The cover window <NUM> may be attached to the touch sensing device <NUM> through an adhesive member <NUM> as shown in <FIG>. The adhesive member <NUM> may be an optically clear adhesive (OCA) film or an optically clear resin (OCR) film.

The cover window <NUM> may include a light transmitting portion DA100 corresponding to a display area DA of the display panel <NUM> and a light blocking portion NDA100 corresponding to a non-display area NDA of the display panel <NUM>. The light blocking portion NDA100 may be formed to be opaque. Or, the light blocking portion NDA100 may be formed as a decorative layer having a pattern that can be seen to a user when an image is not displayed. For example, a company logo such as SAMSUNG® or various characters may be patterned on the light blocking portion NDA100.

The cover window <NUM> may be made of glass, sapphire, and/or plastic. The cover window <NUM> may 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> is a unit for sensing a touch position of a user, and may be implemented as a capacitive type such as a self-capacitance type or a mutual capacitance type.

The touch sensing device <NUM> may be a panel type or a film type. Or, the touch sensing device <NUM> may be formed to be integrated with the display panel <NUM>. For example, when the touch sensing device <NUM> is a film type, the touch sensing device <NUM> may be formed to be integrated with a barrier film of encapsulating the display panel <NUM>.

The touch circuit board <NUM> may be attached to one side of the touch sensing device <NUM>. Specifically, the touch circuit board <NUM> may be attached onto pads provided on one side of the touch sensing device <NUM> using an anisotropic conductive film. Further, the touch circuit board <NUM> may be provided with a touch connection portion <NUM> as shown in <FIG>, and the touch connection portion <NUM> may be connected to a first connector <NUM> of the display circuit board <NUM>. The touch circuit board <NUM> may be a flexible printed circuit board or a chip on film (COF).

The touch driving unit <NUM> may apply touch driving signals to the touch sensing device <NUM>, sense sensing signals from the touch sensing device <NUM>, and analyze the sensing signals to calculate a touch position of the user. The touch driving unit <NUM> may be formed as an integrated circuit and mounted on the touch circuit board <NUM>.

The display panel <NUM> may include a display area DA and a non-display area NDA. The display area DA is an area in which an image is displayed, and the non-display area NDA is an area in which no image is displayed, and may be a peripheral area of the display area DA. The non-display area NDA may be disposed so as to surround the display area DA as shown in <FIG> and <FIG>, but the exemplary embodiments are not limited thereto. The display area DA may be disposed to overlap the light transmitting portion DA100 of the cover window <NUM>, and the non-display area NDA may be disposed to overlap the light blocking portion NDA100 of the cover window <NUM>.

The display panel <NUM> may be a light emitting display panel including a light emitting element. Examples of the display panel <NUM> may include an organic light emitting display panel using an organic light emitting diode, an ultra-small light emitting diode display panel using a micro LED, or a quantum dot light emitting diode display panel using a quantum dot light emitting diode. Hereinafter, the display panel <NUM> will be mainly described as an organic light emitting display panel as shown in <FIG>.

Referring to <FIG>, the display area DA of the display panel <NUM> refers to an area where a light emitting element layer <NUM> is formed to display an image, and the non-display area NDA thereof refers to an area around the display area DA.

The display panel <NUM> may include a support substrate <NUM>, a flexible substrate <NUM>, a thin film transistor layer <NUM>, a light emitting element layer <NUM>, an encapsulation layer <NUM>, and a barrier film <NUM>.

The flexible substrate <NUM> is disposed on the support substrate <NUM>. Each of the support substrate <NUM> and the flexible substrate <NUM> may include a polymer material having flexibility. For example, each of the support substrate <NUM> and the flexible substrate <NUM> may include polyethersulphone (PES), polyacrylate (PA), polyarylate (PAR), polyetherimide (PEI), polyethylenenapthalate (PEN), polyethylene terepthalate (PET), polyphenylenesulfide (PPS), polyallylate, polyimide (PI), polycarbonate (PC), cellulosetriacetate (CAT), cellulose acetate propionate (CAP), or a combination thereof.

The thin film transistor layer <NUM> is disposed on the flexible substrate <NUM>. The thin film transistor layer <NUM> includes thin film transistors <NUM>, a gate insulating film <NUM>, an interlayer insulating film <NUM>, a protective 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> so as to protect thin film transistors <NUM> and light emitting elements from moisture penetrating through the support substrate <NUM> and the flexible substrate <NUM> which are vulnerable to moisture. The buffer film may be formed of a plurality of alternately laminated inorganic films. For example, the buffer film may be formed of a multi-layer film in which one or more inorganic layers including one or more of a silicon oxide (SiOx), a silicon nitride (SiNx), and SiON are alternately stacked. The buffer film may be omitted.

The thin film transistor <NUM> is formed on the buffer film. The thin film transistor <NUM> includes an active layer <NUM>, a gate electrode <NUM>, a source electrode <NUM>, and a drain electrode <NUM>. Although it is shown in <FIG> that the thin film transistor <NUM> is formed by a top gate manner in which the gate electrode <NUM> is located on the active layer <NUM>, it should be noted that the exemplary embodiments are not limited thereto. That is, the thin film transistor <NUM> may be formed by a bottom gate manner in which the gate electrode <NUM> is located beneath the active layer <NUM>, or may be formed by a double gate manner in which the gate electrode <NUM> is located both on and beneath 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 blocking layer for blocking external light incident on the active layer <NUM> may be formed between the buffer film and the active layer <NUM>.

The gate insulating film <NUM> may be formed on the active layer <NUM>. The gate insulating film <NUM> may be formed of an inorganic film, for example, a silicon oxide (SiOx) film, a silicon nitride (SiNx) film, or a combination 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 of a single layer or a multi-layer including at least one of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd) and 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 of an inorganic film, for example, a silicon oxide (SiOx) film, a silicon nitride (SiNx) film, or a combination thereof.

The source electrode <NUM>, the drain electrode <NUM>, and a data line may be formed on the interlayer insulating film. Each of the source electrode <NUM> and the drain electrode <NUM> may be connected to the active layer <NUM> through a contact hole 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 of a single layer or a multi-layer including at least one of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd) and copper (Cu), or an alloy thereof.

The protective film <NUM> for insulating the thin film transistor <NUM> may be formed on the source electrode <NUM>, the drain electrode <NUM>, and the data line. The interlayer insulating film <NUM> may be formed of an inorganic film, for example, a silicon oxide (SiOx) film, a silicon nitride (SiNx) film, or a combination thereof.

The planarization film <NUM> for flattening a step due to the thin film transistor <NUM> may be formed on the protective film <NUM>. The planarization film <NUM> may be formed of an organic film including an acryl resin, an epoxy resin, a phenolic resin, a polyamide resin, or a polyimide resin.

The light emitting element layer <NUM> is formed on the thin film transistor layer <NUM>. The light emitting element layer <NUM> includes 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 element may be an organic light emitting element. In this case, the light emitting element 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> of the thin film transistor <NUM> through a contact hole penetrating the protective film <NUM> and the planarization film <NUM>.

The pixel defining film <NUM> may be formed on the planarization film <NUM> to cover the edge of the anode electrode <NUM> so as to partition pixels. That is, the pixel defining film <NUM> serves to define pixels. Each of the pixels refers to an area where the anode electrode <NUM>, the light emitting layer <NUM>, and the cathode electrode <NUM> are sequentially laminated, and holes from the anode electrode <NUM> and electrons from the cathode electrode <NUM> are combined with each other in the light emitting layer <NUM> to emit light.

The light emitting layer <NUM> is formed on the anode electrode <NUM> and the pixel defining film <NUM>. The light emitting layer <NUM> is an organic light emitting layer. The light emitting layer <NUM> may emit one of red light, green light, and blue light. The peak wavelength range of red light may be about <NUM> to <NUM>, and the peak wavelength range of green light may be about <NUM> to <NUM>. Further, the peak wavelength range of blue light may be about <NUM> to <NUM>. The light emitting layer <NUM> may be a white light emitting layer that emits white light. In this case, the light emitting layer <NUM> may have a laminate structure of a red light emitting layer, a green light emitting layer, and a blue light emitting layer, and may be a common layer formed commonly in the pixels. 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 transporting layer, a light emitting layer, and an electron transporting layer. Further, the light emitting layer <NUM> may be formed to have a tandem structure of two stacks or more, and in this case, a charge generating layer may be formed between the stacks.

The cathode electrode <NUM> is 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 in the pixels.

When the light emitting element layer <NUM> is formed by a top emission manner in which light is emitted upward, the anode electrode <NUM> may be formed of a high-reflectance metal material such as a laminate structure (Ti/Al/Ti) of aluminum and titanium, a laminate structure (ITO/Al/ITO) of aluminum and TIO, an APC alloy, or a laminate structure (ITO/APC/ITO) of an APC alloy and ITO. The APC alloy may be an alloy of silver (Ag), palladium (Pd), and copper alloy (Cu). The cathode electrode <NUM> may be formed of a transparent conductive material (TCO) such as ITO or IZO, which is light-transmissive, or a semi-transmissive conductive material such as magnesium (Mg), silver (Ag), or an alloy of magnesium (Mg) and silver (Ag). When the cathode electrode <NUM> is formed of a semi-transmissive conductive material, light emission efficiency may be increased by a microcavity.

When the light emitting element layer <NUM> is formed by a bottom emission manner in which light is emitted downward, the anode electrode <NUM> may be formed of a transparent conductive material (TCO) such as ITO or IZO, or a semi-transmissive conductive material such as magnesium (Mg), silver (Ag), or an alloy of magnesium (Mg) and silver (Ag). The cathode electrode <NUM> may be formed of a high-reflectance metal material such as a laminate structure (Ti/Al/Ti) of aluminum and titanium, a laminate structure (ITO/Al/ITO) of aluminum and TIO, an APC alloy, or a laminate structure (ITO/APC/ITO) of an APC alloy and ITO. When the anode electrode <NUM> is formed of a semi-transmissive conductive material, light emission efficiency may be increased by a microcavity.

The encapsulation layer <NUM> is formed on the light emitting element layer <NUM>. The encapsulation layer <NUM> serves to prevent or limit oxygen or moisture from permeating the light emitting layer <NUM> and the cathode electrode <NUM>. For this purpose, 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 film may be formed to have a sufficient thickness to prevent or limit foreign matter (particles) from penetrating the encapsulation layer <NUM> and entering the light emitting layer <NUM> and the cathode electrode <NUM>. The organic film may include any one of epoxy, acrylate, and urethane acrylate.

The barrier film <NUM> is disposed on the encapsulation layer <NUM>. The barrier film <NUM> is disposed so as to cover the encapsulation layer <NUM> to protect the light emitting element layer <NUM> from oxygen and moisture. The barrier film <NUM> may be formed to be integrated with the touch sensing device <NUM>.

A polarizing film may be additionally attached to the upper surface of the display panel <NUM> so as to prevent or reduce the deterioration of visibility due to external light reflection.

The display circuit board <NUM> may be attached to one side of the display panel <NUM>. Specifically, the display circuit board <NUM> may be attached onto pads provided on one side of the display panel <NUM> using an anisotropic conductive film.

The touch circuit board <NUM> and the display circuit board <NUM> may be bent downward from the top of the display panel <NUM> as shown in <FIG>. In contrast, the sound circuit board <NUM> is not bent because it is disposed under the panel lower support <NUM>. The display circuit board <NUM> may be connected to the touch connection portion <NUM> of the touch circuit board <NUM> through the first connector <NUM>. The display circuit board <NUM> may be connected to the sound connection portion <NUM> of the sound circuit board <NUM> through the second connector <NUM>. The display circuit board <NUM> may be connected to the main circuit board <NUM> through the third connector <NUM>. It is illustrated in <FIG> that the display circuit board <NUM> includes first, second, and third connectors <NUM>, <NUM>, and <NUM>. However, the exemplary embodiments are not limited thereto. For example, the display circuit board <NUM> may include pads corresponding to the first and second connectors <NUM> and <NUM> instead of the first and second connectors <NUM> and <NUM>. In this case, the display circuit board <NUM> may be connected to the touch circuit board <NUM> and the sound circuit board <NUM>.

The display driving unit <NUM> outputs signals and voltages for driving the display panel <NUM> through the display circuit board <NUM>. The display driving unit <NUM> may be formed as an integrated circuit and 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 to one side of the display panel <NUM>.

The panel lower support <NUM> may be disposed under the display panel <NUM>. The panel lower support <NUM> may include at least one of a heat dissipating layer for efficiently dissipating the heat of the display panel <NUM>, an electromagnetic wave blocking layer for blocking electromagnetic waves, a light blocking layer for blocking external light, a light absorbing layer for absorbing external light, and a buffer layer for absorbing an external impact.

Specifically, as shown in <FIG>, the panel lower support <NUM> may include a light absorbing member <NUM>, a buffer member <NUM>, a heat dissipating member <NUM>, and first, second, and third adhesive layers <NUM>, <NUM>, and <NUM>.

The light absorbing member <NUM> may be disposed under the display panel <NUM>. The light absorbing member <NUM> inhibits the transmission of light to prevent or limit components disposed under the light absorbing member, that is, a first sound generator and the like from being viewed from above the display panel <NUM>. The light absorbing member <NUM> may include a light absorbing material such as a black pigment or a dye.

The buffer member <NUM> may be disposed under the light absorbing member <NUM>. The buffer member <NUM> absorbs an external impact to prevent or reduce damage to the display panel <NUM>. The buffer member <NUM> may be composed of a single layer or a plurality of layers. For example, the buffer member <NUM> may be formed of a polymer resin such as polyurethane, polycarbonate, polypropylene, or polyethylene, or may be formed of an elastic material such as a rubber, a urethane material, or a sponge formed by foaming an acrylic material. The buffer member <NUM> may be a cushion layer.

The heat dissipating member <NUM> may be disposed under the buffer member <NUM>. The heat dissipating member <NUM> may include at least one heat dissipating layer. For example, as shown in <FIG>, the heat dissipating member <NUM> may include a first heat dissipating layer <NUM> including graphite or carbon nanotubes, a second heat dissipating layer <NUM> capable of blocking electromagnetic waves and formed of a metal thin film of copper, nickel, ferrite or silver having excellent thermal conductivity, and a fourth adhesive layer <NUM> for attaching the first heat dissipating layer <NUM> to the second heat dissipating layer <NUM>.

The first adhesive layer <NUM> attaches the light absorbing member <NUM> to the lower surface of the display panel <NUM>. The second adhesive layer <NUM> attaches the buffer member <NUM> to the lower surface of the light absorbing member <NUM>. The third adhesive layer <NUM> attaches the heat dissipating member <NUM> to the lower surface of the buffer member <NUM>. Each of the first, second, and third adhesive layers <NUM>, <NUM>, and <NUM> may contain a silicon-based polymer, a urethane-based polymer, an SU polymer having a silicon-urethane hybrid structure, an acrylic polymer, an isocyanate-based polymer, polyvinyl alcohol, gelatin, latex, polyester, or aqueous polyester.

The first sound generator <NUM> may be disposed on the lower surface of the panel lower support <NUM>. When the first sound generator <NUM> is disposed on the heat dissipating member <NUM> of the panel lower support <NUM>, the first heat dissipating layer <NUM> or second heat dissipating layer <NUM> of the heat dissipating member <NUM> may be broken by the vibration of the first sound generator <NUM>. Therefore, in the region where the first sound generator <NUM> is disposed, the heat dissipating member <NUM> may be removed, and the first sound generator <NUM> may be disposed on the buffer member <NUM>.

The first sound generator <NUM> may output a first sound by generating vibration in response to a first sound signal. For this purpose, the first sound generator <NUM> may be vibrated by a vibration layer <NUM> deformed in response to the first sound signal. The first sound generator <NUM> may also be vibrated by an electromagnetic force generated by applying a current corresponding to the first sound signal to a coil surrounding a magnet. Hereinafter, it will be mainly described that the first sound generator <NUM> generates a sound by the vibration of the vibration layer <NUM>.

As shown in <FIG> and <FIG>, the first sound generator <NUM> may include a first electrode <NUM>, a second electrode <NUM>, a vibration layer <NUM>, a substrate <NUM>, a first pad <NUM>, and a second pad <NUM>.

The first electrode <NUM> may be disposed on a first surface of the substrate <NUM>, the vibration layer <NUM> may be disposed on the first electrode <NUM>, and the second electrode <NUM> may be disposed on the vibration layer <NUM>. The first pad <NUM> and the second pad <NUM> may be disposed on a second surface of the substrate <NUM>.

The first electrode <NUM> and the second electrode <NUM> may be made of a conductive material. For example, the conductive material may be a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO), an opaque metal material, a conductive polymer, or carbon nanotubes (CNT).

The first electrode <NUM> may be connected to the first pad <NUM> through a first contact hole CH1 penetrating the substrate <NUM>. Thus, the first electrode <NUM> may receive a first driving voltage from the sound driving unit <NUM> of the sound circuit board <NUM> through the first pad <NUM>.

The second electrode <NUM> may be connected to the second pad <NUM> through a second contact hole CH2 penetrating the vibration layer <NUM> and the substrate <NUM>. Thus, the second electrode <NUM> may receive a second driving voltage from the sound driving unit <NUM> of the sound circuit board <NUM> through the second pad <NUM>.

The vibration layer <NUM> may be a piezo actuator that is deformed as shown in <FIG> according to a difference between the voltage applied to the first electrode <NUM> and the voltage applied to the second electrode <NUM>. In this case, the vibration layer <NUM> may be at least one of a piezoelectric body such as a poly vinylidene fluoride (PVDF) film or a lead zirconate titanate (PZT) ceramic film, and an electroactive polymer film.

In this case, the vibration layer <NUM> is contracted by the first force F1 or is relaxed or expanded by the second force F2 according to the difference between the first driving voltage applied to the first electrode <NUM> and the second driving voltage applied to the second electrode <NUM>. Specifically, as shown in <FIG>, in the case where the vibration layer <NUM> adjacent to the first electrode <NUM> has negative polarity and the vibration layer <NUM> adjacent to the second electrode <NUM> has positive polarity, when the first driving voltage of negative polarity is applied to the first electrode <NUM> and the second driving voltage of positive polarity is applied to the second electrode <NUM>, the vibration layer <NUM> may be contracted by the first force F1. Further, in the case where the vibration layer <NUM> adjacent to the first electrode <NUM> has negative polarity and the vibration layer <NUM> adjacent to the second electrode <NUM> has positive polarity, when the first driving voltage of positive polarity is applied to the first electrode <NUM> and the second driving voltage of negative polarity is applied to the second electrode <NUM>, the vibration layer <NUM> may be relaxed by the second force F2. When the first driving voltage applied to the first electrode <NUM> and the second driving voltage applied to the second electrode <NUM> are alternately repeated in positive and negative polarities, the vibration layer <NUM> repeatedly contracts and relaxes. Accordingly, the first sound generator <NUM> vibrates, and thus the display panel <NUM> vibrates vertically, so as to output a first sound.

Further, the display panel <NUM> is vibrated by the first sound generator <NUM> to output the first sound, so that the display panel <NUM> serves as a diaphragm. The greater the size of the diaphragm, the greater the intensity of the sound pressure output from the diaphragm. Since the size of the diaphragm of the speaker applied to the display device is smaller than the area of the display panel <NUM>, when the display panel <NUM> is used a diaphragm, the intensity of sound pressure may increase compared to when a speaker is used.

Further, since the first sound generator <NUM> may vibrate the display panel <NUM> to output the first sound, the display device <NUM> may output a sound by a sound generator not exposed to the outside. Thus, the sound generator disposed on the front surface of the display device <NUM> may be deleted, so that the area of the light transmitting portion DA100 of the cover window <NUM> may be increased. That is, the display area of the display device <NUM> may be enlarged.

The substrate <NUM> may be made of an insulating material, for example, plastic.

The first pad <NUM> and the second pad <NUM> may be connected to the sound circuit board <NUM>. The first pad <NUM> and the second pad <NUM> may be formed of a conductive material.

The first sound generator <NUM> may be connected to the sound circuit board <NUM>. Specifically, the sound circuit board <NUM> may be attached onto the first and second pads <NUM> and <NUM> of the first sound generator <NUM> using an anisotropic conductive film. Further, the sound circuit board <NUM> may be provided with the sound connection portion <NUM> as shown in <FIG>, and the sound connection portion <NUM> may be connected to the second connector <NUM> of the display circuit board <NUM>. The sound circuit board <NUM> may be a flexible printed circuit board or a chip on film (COF).

The sound driving unit <NUM> may be formed of an integrated circuit, and may be mounted on the sound circuit board <NUM>. The sound driving unit <NUM> may generate a first sound signal in response to first sound data provided from the main processor <NUM> of the main circuit board <NUM>. In this case, the first sound data of the main processor <NUM> may be provided to the sound driving unit <NUM> via the main circuit board <NUM>, the display circuit board <NUM>, and the sound circuit board <NUM>, and the first sound signal of the sound driving unit <NUM> may be transmitted to the first sound generator <NUM> through the first sound signal.

The sound driving unit <NUM> may include a digital signal processor (DSP) processing a first sound data as a digital signal, a digital analog converter (DAC) converting the first sound data processed in the digital signal processor into a first sound signal as an analog signal, and an amplifier (AMP) amplifying and outputting the first sound signal converted in the digital analog converter.

In the display device according to an exemplary embodiment, the first sound generator <NUM> is attached to the panel lower support <NUM> disposed under the display panel <NUM> and is connected to the sound circuit board <NUM> mounted with the sound driving unit <NUM>, and the sound driving unit <NUM> is connected to the display circuit board <NUM>, thereby making the first sound generator <NUM> and the sound circuit board <NUM> into one module together with the display panel <NUM>.

The pressure sensing device <NUM> may be attached to the lower portion of the panel lower support <NUM>. The pressure sensing device <NUM> may include a pressure sensor capable of sensing the pressure pressed by the user. The pressure sensing device may be implemented as a capacitive or resistive type pressure sensing device.

The pressure sensing device <NUM> may be formed in the form of a panel or a film. Or, the pressure sensing device <NUM> may be formed to be integrated with the touch sensing device <NUM>. The pressure sensing device <NUM> may be removed in the region where the first sound generator <NUM> is disposed as shown in <FIG> and <FIG>, so as to prevent or reduce interference with the first sound generator <NUM>.

A pressure sensing circuit board <NUM> may be attached to one side of the pressure sensing device <NUM>. The pressure sensing circuit board <NUM> may be attached to pads provided on one side of the pressure sensing device <NUM> using an anisotropic conductive film. The pressure sensing circuit board <NUM> may be provided with a pressure sensing connection portion <NUM> as shown in <FIG>, and the pressure sensing connection portion <NUM> may be connected to a connector <NUM> of the touch circuit board <NUM>. The pressure sensing connection portion <NUM> may be attached onto the pads of the touch circuit board <NUM> using an anisotropic conductive film instead of the connector <NUM>. The pressure sensing connection portion <NUM> may be connected to the display circuit board <NUM>, not to the touch circuit board <NUM>. The pressure sensing circuit board <NUM> may be a flexible printed circuit board or a chip on film (COF).

The pressure sensing unit <NUM> applies pressure driving signals PS to the pressure sensing device <NUM> and receives pressure sensing signals PDS from the pressure sensing device <NUM>. The pressure sensing unit <NUM> may analyze the pressure sensing signals PDS to calculate degree of pressure that the user presses the front surface of the display device <NUM>, that is, pressure information. The pressure sensing unit <NUM> may be formed as an integrated circuit and mounted on the pressure sensing circuit board <NUM>. The pressure sensing unit <NUM> may be formed to be integrated with the touch driving unit <NUM>, and in this case, the pressure sensing unit <NUM> mounted on the pressure sensing circuit board <NUM> may be omitted.

The lower bracket <NUM> may be disposed under the panel lower support <NUM> and the sound circuit board <NUM>. The lower bracket <NUM> may be disposed to surround the cover window <NUM>, the touch sensing device <NUM>, the display panel <NUM>, the panel lower support <NUM>, the first sound generator <NUM>, the touch circuit board <NUM>, the display circuit board <NUM>, and the sound circuit board <NUM>. The lower bracket <NUM> may include a synthetic resin, a metal, or both a synthetic resin and a metal.

In the display device <NUM> according to an exemplary embodiment, the side surface of the lower bracket <NUM> may be exposed to the side surface of the display device <NUM>, or the lower bracket <NUM> may be omitted and only the lower cover <NUM> may be provided.

The main circuit board <NUM> may be disposed under the lower bracket <NUM>. The main circuit board <NUM> may be connected to the third connector <NUM> of the display circuit board <NUM> through a cable connected to the main connector <NUM>. Thus, the main circuit board <NUM> may be connected to the display circuit board <NUM>, the touch circuit board <NUM>, and the sound circuit board <NUM>. The main circuit board <NUM> may be a printed circuit board or a flexible printed circuit board.

As shown in <FIG>, the main circuit board <NUM> may include a main processor <NUM>, a second sound generator <NUM>, a charging terminal <NUM>, and a camera <NUM>. Although it is illustrated in <FIG> that the main processor <NUM>, the second sound generator <NUM>, the charging terminal <NUM>, and the camera <NUM> are disposed one surface of the main circuit board <NUM>, the one surface facing the lower bracket <NUM>, but the exemplary embodiments are not limited thereto. That is, the main processor <NUM>, the second sound generator <NUM>, the charging terminal <NUM>, and the camera <NUM> may be disposed the other surface of the main circuit board <NUM>, the other surface facing the lower cover <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> such that the display panel <NUM> displays an image. Further, the main processor <NUM> may output the first sound data to the sound driving unit <NUM> of the sound circuit board <NUM> via the display circuit board <NUM> such that the first sound generator <NUM> outputs a sound. Further, the main processor <NUM> may output the second sound data to the second sound generator <NUM> such that the second sound generator <NUM> outputs sound. The first sound data may be digital data, and the second sound data may be an analog signal. Moreover, the main processor <NUM> may control the driving of the camera <NUM>. The main processor <NUM> may be an application processor, a central processing unit, or a system chip, each including an integrated circuit.

The second sound generator <NUM> may be a speaker. Specifically, the second sound generator <NUM> may receive the second sound data directly from the main processor <NUM> or may receive the second sound data amplified from an amplifier for the second sound generator <NUM>. The second sound generator <NUM> may output a second sound in accordance with the second sound data.

The second sound generator <NUM> may be disposed on one side of the main circuit board <NUM>. For example, as shown in <FIG>, the second sound generator <NUM> is disposed on one side of the main circuit board <NUM> to provide the second sound to the lower side of the display device <NUM> through speaker holes SH1 and SH2 disposed one side of the lower cover <NUM>. Although it is illustrated in <FIG> and <FIG> that the second sound generator <NUM> includes a first sub-sound generator <NUM> disposed at one side of the charging terminal <NUM> and a second sub-sound generator <NUM> disposed at the other side of the charging terminal <NUM>, the charging terminal being disposed between the first sub sound generator <NUM> and the second sub sound generator <NUM> of the second sound generator <NUM>, but the exemplary embodiments are not limited thereto. For example, the second sound generator <NUM> may be disposed on only one of both sides of the charging terminal <NUM>. Further, the charging terminal <NUM> may be disposed at any one of the position where the first sub sound generator <NUM> is disposed and the position where the second sub sound generator <NUM> is disposed, and the second sound generator <NUM> may be disposed at other positions where the charging terminal <NUM> is not disposed.

The charging terminal <NUM> is a terminal receiving a power from the outside, and may be connected to a power supply unit of the main circuit board <NUM>.

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

In addition, the main circuit board <NUM> may be further provided with a mobile communication module capable of transmitting and receiving a radio signal to/from at least one of a base station, an external terminal, and a server. The radio signal may include various types of data depending on a voice signal, a video call signal, or a text/multimedia message transmission/reception.

The lower cover <NUM> may be disposed under the lower bracket <NUM> and the main circuit board <NUM>. The lower cover <NUM> may form a lower surface appearance of the display device <NUM>. The lower cover <NUM> may be provided on one side surface thereof with a charging terminal hole CT and speaker holes for outputting the sound of the second sound generator <NUM>. The lower cover <NUM> may include plastic and/or metal.

<FIG> is a graph showing the sound pressure level of a sound provided to a user's ear in different situations. <FIG> and <FIG> are schematic view illustrating a case where the display device contacts the user's ear and a case where the display device does not contact the user's ear.

Particularly, <FIG> illustrates a graph showing the sound pressure level of a sound provided to a user's ear with respect to a wavelength when the user's ear does not contact the display device, when the user's ear contacts the display device without pressure, when the user's ear contacts the display device by first pressure, and when the user's ear contacts the display device by second pressure.

When a user makes a call using the display device <NUM>, <FIG> shows a sound pressure level (SPL) FB1 when the user's ear does not contact the front surface of the display device <NUM>, a sound pressure level FB2 when the user's ear contacts the front surface of the display device <NUM> without pressure, a sound pressure level FB3 when the user's ear contacts the front surface of the display device <NUM> by first pressure, and a sound pressure level FB4 when the user's ear contacts the front surface of the display device <NUM> by second pressure. As shown in <FIG>, there is a difference in sound level pressure of sounds generated by the first sound generator <NUM> of the display device <NUM> in the aforementioned four cases.

Each of the sound pressure levels FB2, FB3, and FB4 when the user's ear EAR contacts the front surface of the display device <NUM> as shown in <FIG> is increased by about <NUM> dB or more in a frequency range of <NUM> or less as compared with the sound pressure level FB1 when the user's ear EAR does not contact the front surface of the display device <NUM> as shown in <FIG>. Further, as the pressure of the user's ear EAR contacting the front surface of the display device <NUM>, the sound pressure level in the frequency range of <NUM> or less is increased by 7dB to <NUM> dB, and is similar to a sound pressure level in a frequency range of <NUM> or more.

Accordingly, when the user makes a call using the display device <NUM>, the pressure sound level is adjusted for each frequency range according to whether the user's ear EAR contacts the front surface of the display device <NUM> and whether the user's ear EAR contacts the front surface of the display device <NUM> to such a degree of pressure, and thus it is required to provide optimal call quality to the user. Hereinafter, details thereof will be described with reference to the drawings.

<FIG> is a block diagram showing a main processor <NUM>, a sound driving unit <NUM>, a first sound generator <NUM>, a touch driving unit <NUM>, a touch sensing device <NUM>, a pressure sensing unit <NUM>, and a pressure sensing device <NUM> in the display device according to an exemplary embodiment. <FIG> is a block diagram showing an example of the main processor <NUM> and sound driving unit <NUM> of <FIG>.

Referring to <FIG> and <FIG>, the touch driving unit <NUM> applies touch driving signals TS to the touch sensing device <NUM> and receives sensing signals DS from the touch sensing device <NUM>. The touch driving unit <NUM> may calculate the touch position of the user by analyzing the sensing signals DS.

The pressure sensing unit <NUM> applies pressure driving signals PS to the pressure sensing device <NUM> and receives pressure sensing signals PDS from the pressure sensing device <NUM>. The pressure sensing unit <NUM> may analyze the pressure sensing signals PDS to calculate the degree to which the user presses the front surface of the display device <NUM>. The pressure sensing unit <NUM> outputs pressure data PD including information about the pressure the user presses the display device <NUM> to the main processor <NUM>.

As shown in <FIG>, the main processor <NUM> may include a digital signal processor <NUM>. The digital signal processor <NUM> modulates first sound data SD1 and second sound data SD2 to be output to the sound driving unit <NUM> for each frequency range on the basis of touch data TD and pressure data PD. The digital signal processor <NUM> outputs the modulated first sound data SD1 and second sound data SD2 to the sound driving unit <NUM>. A method of modulating the first sound data SD1 and second sound data SD2 of the digital signal processor <NUM> will be described in detail with reference to <FIG>.

As shown in <FIG>, the sound driving unit <NUM> includes a digital-analog converter <NUM> and an amplifier <NUM>. The digital-analog converter <NUM> converts first modulated sound data SD1 and second modulated sound data SD2 into a first driving voltage DV1 and a second driving voltage DV2. The amplifier <NUM> amplifies the first driving voltage DV1 and the second driving voltage DV2 and outputs the amplified first driving voltage DV1 and the amplified second driving voltage DV2 to the first sound generator <NUM>.

<FIG> is a flowchart showing a method of driving a display device according to an exemplary embodiment. <FIG> is a graph the sound pressure levels of sounds output from a first sound generator with respect to a wavelength in a first operating mode, and <FIG> is a table showing the increase and decrease of driving voltages applied to the first sound generator. <FIG> is a graph the sound pressure levels of sounds output from a first sound generator with respect to a wavelength in a second operating mode, and <FIG> is a table showing the increase and decrease of driving voltages applied to the first sound generator. <FIG> is a graph the sound pressure levels of sounds output from a first sound generator with respect to a wavelength in a third operating mode, and <FIG> is a table showing the increase and decrease of driving voltages applied to the first sound generator.

Referring to <FIG>, first, the main processor <NUM> determines whether the display device <NUM> is operating in a call mode. The call mode refers to a mode in which a user performs a voice call or a video call through a mobile communication module of the main circuit board <NUM> (S101 in <FIG>).

Second, the main processor <NUM> determines whether the user's ear is in contact with the front surface of the display device <NUM> by the touch sensing device <NUM> when the display device <NUM> is operating in the call mode. The main processor <NUM> controls the sound output of the first sound generator <NUM> in the first operating mode when the user's ear is not in contact with the front surface of the display device <NUM> by the touch sensing device <NUM> (S <NUM> in <FIG>).

Third, the main processor <NUM> modulates the first sound data SD1 and the second sound data SD2 such that the sound pressure level of the sound generated by the first sound generator <NUM> in the first operating mode is between the first sound pressure level SPL1 and the second sound pressure level SPL2 in the first frequency range FR1, is between the third sound pressure level SPL3 and the second sound pressure level SPL2 in the second frequency range FR2, and is between the first sound pressure level SPL1 and the second sound pressure level SPL2 in the third frequency range FR3. The first frequency range FR1 refers to a range where a wavelength is greater than <NUM> and is less than or equal to <NUM>, the second frequency range FR2 refers to a range where the wavelength is greater than <NUM> and is less than or equal to <NUM>, and the third frequency range FR3 refers to a range where the wavelength is greater than <NUM> and is less than or equal to <NUM> (S103 in <FIG>).

Specifically, the first curve C1 of <FIG> indicates the sound pressure level of a sound generated by the first sound generator <NUM> in accordance with the first sound data SD1 and second sound data SD2, which are not modulated according to an exemplary embodiment, when the user's ear is not in contact with the first surface of the display device <NUM>. The first curve C1' of <FIG> indicates the sound pressure level of a sound generated by the first sound generator <NUM> in accordance with the first sound data SD1 and second sound data SD2, which are modulated according to an exemplary embodiment, when the user's ear is not in contact with the front surface of the display device <NUM>.

When the sound pressure level is between the third sound pressure level SPL3 and the second sound pressure level SPL2 at a frequency of <NUM> to <NUM> as shown in <FIG>, the sound pressure level may be maintained uniformly regardless of frequency, thereby providing optimal sound quality to the user. However, when the user's ear is not in contact with the front surface of the display device <NUM> as in the first curve C1 of <FIG>, the sound pressure level of the sound generated by the first sound generator <NUM> is not uniform in the first, second, and third frequency ranges FR1, FR2, and FR3. That is, the sound pressure level is lower than the third sound pressure level SPL3 in the range where the frequency is lower than <NUM> in the first frequency range FR1 and the second frequency range FR2 as in the first curve C1 of <FIG>. Further, the sound pressure level is lower than the third sound pressure level SPL3 in the third frequency range FR3 and the range where the frequency is <NUM> or more in the second frequency range FR2 and the second frequency range FR2 as in the first curve C1 of <FIG>.

Therefore, in order to provide optimal sound quality to the user by maintaining the sound pressure level regardless of frequency, the sound pressure level in the first frequency range FR1 should be increased than the third sound pressure level SPL3, and the sound pressure level should be lowered in the second frequency range FR2 and the third frequency range FR3, as in the first curve C1' of <FIG>. Whether to increase or decrease the sound pressure level in each frequency range is determined based on the maximum value of the sound pressure level in each frequency range. Therefore, it is necessary to further lower the sound pressure level in the third frequency range FR3 than the sound pressure level in the second frequency range FR2.

For this purpose, the digital signal processor <NUM> of the main processor <NUM> modulates the first sound data SD1 and the second sound data SD2 for each frequency range. Specifically, as the voltage difference between the first driving voltage DV1 applied to the first electrode <NUM> of the first sound generator <NUM> and the second driving voltage DV2 applied to the second electrode <NUM> thereof increases, the vibration intensity of the vibration layer <NUM> of the first sound generator <NUM> increases. Accordingly, in order to allow the sound pressure level to be higher than the third sound pressure level SPL3 in the first frequency range FR1, the digital signal processor <NUM> modulates the first sound data SD1 and the second sound data SD2 so as to increase the voltage difference between the first driving voltage DV1 and second driving voltage DV2 applied to the first sound generator <NUM> as shown in <FIG>. Further, in order to lower the sound pressure level in the second frequency range FR2, the digital signal processor <NUM> modulates the first sound data SD1 and the second sound data SD2 so as to decrease the voltage difference between the first driving voltage DV1 and second driving voltage DV2 applied to the first sound generator <NUM> as shown in <FIG>. In this case, as shown in <FIG>, the reduced value of the voltage difference between the first driving voltage DV1 and the second driving voltage DV2 in the third frequency range FR3 may be greater than the reduced value of the voltage difference between the first driving voltage DV1 and the second driving voltage DV2 in the second frequency range FR2. Consequently, the digital signal processor <NUM> modulates the first sound data SD1 and the second sound data SD2 in consideration of whether to increase and decrease the voltage difference between the first driving voltage DV1 and second driving voltage DV2 applied to the first sound generator <NUM> in the first, second, and third frequency ranges FR1, FR2, and FR3.

Fourth, the main processor <NUM> determines whether the pressure sensed by the pressure sensing device <NUM> is equal to or less than the first pressure when the user's ear is in contact with the front surface of the display device <NUM> by the touch sensing device <NUM>. The main processor <NUM> controls the sound output of the first sound generator <NUM> in the second operating mode when the pressure sensed by the pressure sensing device <NUM> is equal to or less than the first pressure (S104 in <FIG>).

Fifth, the main processor <NUM> modulates the first sound data SD1 and the second sound data SD2 such that the sound pressure level of the sound generated by the first sound generator <NUM> in the second operating mode is between the first sound pressure level SPL1 and the second sound pressure level SPL2 in the first frequency range FR1, is between the third sound pressure level SPL3 and the second sound pressure level SPL2 in the second frequency range FR2, and is between the first sound pressure level SPL1 and the second sound pressure level SPL2 in the third frequency range FR3 (S105 in <FIG>).

Specifically, the second curve C2 of <FIG> indicates the sound pressure level of a sound generated by the first sound generator <NUM> in accordance with the first sound data SD1 and second sound data SD2, which are not modulated according to an exemplary embodiment, when the pressure of the user's ear pressing the front surface of the display device <NUM> is equal to or lower than the first pressure. The second curve C2' of <FIG> indicates the sound pressure level of a sound generated by the first sound generator <NUM> in accordance with the first sound data SD1 and second sound data SD2, which are modulated according to an exemplary embodiment, when the pressure of the user's ear pressing the front surface of the display device <NUM> is equal to or lower than the first pressure.

When the sound pressure level is between the third sound pressure level SPL3 and the second sound pressure level SPL2 at a frequency of <NUM> to <NUM> as shown in <FIG>, the sound pressure level may be maintained uniformly regardless of frequency, thereby providing optimal sound quality to the user. However, when the pressure of the user's ear pressing the front surface of the display device <NUM> is equal to or lower than the first pressure as in the second curve C2 of <FIG>, the sound pressure level of the sound generated by the first sound generator <NUM> is not uniform in the first, second, and third frequency ranges FR1, FR2, and FR3. That is, the sound pressure level is increased and decreased in the vicinity of the third sound pressure level SPL3 in the first frequency range FR1 and is present between the third sound pressure level SPL3 and the second sound pressure level SPL2 in the second frequency range FR2 as in the second curve C2 of <FIG>. Further, as in the second curve C2 of <FIG>, the maximum value of the sound pressure level has the second sound pressure level SPL2 in a range where the frequency is <NUM> to <NUM> in the third frequency range FR3.

Therefore, in order to provide optimal sound quality to the user by maintaining the sound pressure level regardless of frequency, the sound pressure level in the first frequency range FR1 should be increased than the third sound pressure level SPL3, and the sound pressure level should be lowered in the second frequency range FR2 and the third frequency range FR3, as in the second curve C2' of <FIG>. Whether to increase or decrease the sound pressure level in each frequency range is determined based on the maximum value of the sound pressure level in each frequency range. Therefore, it is necessary to further lower the sound pressure level in the third frequency range FR3 than the sound pressure level in the second frequency range FR2.

For this purpose, the digital signal processor <NUM> of the main processor <NUM> modulates the first sound data SD1 and the second sound data SD2 for each frequency range. Specifically, in order to allow the sound pressure level to be higher than the third sound pressure level SPL3 in the first frequency range FR1, the digital signal processor <NUM> modulates the first sound data SD1 and the second sound data SD2 so as to increase the voltage difference between the first driving voltage DV1 and second driving voltage DV2 applied to the first sound generator <NUM> as shown in <FIG>. Further, in order to lower the sound pressure level in the second frequency range FR2, the digital signal processor <NUM> modulates the first sound data SD1 and the second sound data SD2 so as to decrease the voltage difference between the first driving voltage DV1 and second driving voltage DV2 applied to the first sound generator <NUM> as shown in <FIG>. In this case, as shown in <FIG>, the reduced value of the voltage difference between the first driving voltage DV1 and the second driving voltage DV2 in the third frequency range FR3 may be greater than the reduced value of the voltage difference between the first driving voltage DV1 and the second driving voltage DV2 in the second frequency range FR2. Consequently, the digital signal processor <NUM> modulates the first sound data SD1 and the second sound data SD2 in consideration of whether to increase and decrease the voltage difference between the first driving voltage DV1 and second driving voltage DV2 applied to the first sound generator <NUM> in the first, second, and third frequency ranges FR1, FR2, and FR3.

Sixth, the main processor <NUM> determines whether the pressure sensed by the pressure sensing device <NUM> is greater than the first pressure and equal to or less than the second pressure when the user's ear is in contact with the front surface of the display device <NUM> by the touch sensing device <NUM>. The main processor <NUM> controls the sound output of the first sound generator <NUM> to the third operating mode when the pressure sensed by the pressure sensing device <NUM> is greater than the first pressure and equal to or less than the second pressure. Further, the main processor <NUM> controls the sound output of the first sound generator <NUM> to the fourth operating mode when the pressure sensed by the pressure sensing device <NUM> is greater than the second pressure (S106 in <FIG>).

Although the main processor <NUM> does not modulate the first sound data SD1 and the second sound data SD2 in the third operating mode as shown in <FIG>, the sound pressure level of the sound generated by the first sound generator <NUM> is between the third sound pressure level SPL3 and the second sound pressure level SPL2 at a frequency of <NUM> to <NUM>. Therefore, the main processor <NUM> does not modulate the first sound data SD1 and the second sound data SD2 in the third operating mode as shown in <FIG>.

Seventh, the main processor <NUM> increases the sound pressure level in the first frequency range FR1 in the fourth operating mode and decreases the sound pressure level in the second frequency range FR2 and the third frequency range FR3 (S <NUM><NUM> of <FIG>).

<FIG> is an exemplary view showing the directionality of a sound generated by the first sound generator when the front surface of the display device does not contact an object. <FIG> is an exemplary view showing the directionality of a sound generated by the first sound generator when the front surface of the display device contacts an object. <FIG> is a graph the sound pressure level of a sound generated by a first sound generator with respect to a wavelength in a fourth operating mode.

Specifically, when the user is in a highly noisy environment in the call mode, the user generally presses the front surface of the display device <NUM> with his ear in order to easily listen to the voice of the counterpart. Further, as shown in <FIG>, when the front surface of the display device <NUM> is not in contact with an object, the sound generated by the first sound generator <NUM> is diverted in all directions. However, as shown in <FIG>, when the front surface of the display device <NUM> is in contact with the object, a sound having a sound pressure level of <NUM> or less, of the sound generated by the first sound generator <NUM>, is directed forward, and a sound having a sound pressure level of <NUM> or more, of the sound generated by the first sound generator <NUM>, is diverted in all directions.

Therefore, when the user is in a highly noisy environment in the call mode, if the sound pressure level of the sound of <NUM> or less with high directivity forward is increased, the user can smoothly listen to the voice of the counterpart. Accordingly, the main processor <NUM> may increase the sound pressure level of the sound in the frequency range of <NUM> or less and decrease the sound pressure level of the sound in the frequency range higher than <NUM> as shown in <FIG>. For example, the main processor <NUM> may include a low pass filter passing a frequency of <NUM> or less and blocking a frequency of more than <NUM>. In this case, the sound pressure level of a sound generated by the first sound generator <NUM> greatly decreases at a frequency of <NUM> or more. Thus, the sound pressure level of the sound generated by the first sound generator <NUM> may be equal to or lower than the fourth sound pressure level SPL4 at a frequency of <NUM> or more. The fourth sound pressure level SPL4 may be lower than the third sound pressure level SPL3, and may be, for example, <NUM> dB or less.

The main processor <NUM> may increase the sound pressure level in the first frequency range FR1 in the fourth operating mode, and may decrease the sound pressure level in the second frequency range FR2 and the third frequency range FR3. For this purpose, the digital signal processor <NUM> of the main processor <NUM> modulates the first sound data SD1 and the second sound data SD2 for each frequency range. Specifically, in order to increase the sound pressure level in the first frequency range FR1, the digital signal processor <NUM> modulates the first sound data SD1 and the second sound data SD2 so as to increase the voltage difference between the first driving voltage DV1 and second driving voltage DV2 applied to the first sound generator <NUM>. Further, in order to decrease the sound pressure level in the second frequency range FR2 and the third frequency range FR3, the digital signal processor <NUM> modulates the first sound data SD1 and the second sound data SD2 so as to decrease the voltage difference between the first driving voltage DV1 and second driving voltage DV2 applied to the first sound generator <NUM> as shown in <FIG>. Consequently, the digital signal processor <NUM> modulates the first sound data SD1 and the second sound data SD2 in consideration of whether to increase and decrease the voltage difference between the first driving voltage DV1 and second driving voltage DV2 applied to the first sound generator <NUM> in the first, second, and third frequency ranges FR1, FR2, and FR3.

As described above, in the display device <NUM> according to the driving method shown in <FIG>, the digital signal processor <NUM> modulates the first sound data SD1 and the second sound data SD2 in consideration of whether the user's ear contacts the front surface of the display device <NUM> and the pressure of the user's ear pressing the front surface of the display device <NUM>, thereby increasing and decreasing the sound pressure level for each frequency range. Therefore, since the sound pressure level can be uniformly maintained in a low-frequency range, a middle-frequency range, and a high-frequency range regardless of whether the user's ear contacts the front surface of the display device <NUM> and the pressure of the user's ear pressing the front surface of the display device <NUM>, high-quality sound can be provided.

<FIG> is a flowchart showing a method of driving a display device according to another exemplary embodiment. <FIG> and <FIG> are exemplary views showing the contact areas of the user's ear contacting the display device.

S201, S202, and S203 shown in <FIG> are substantially the same as S101, S102, and S <NUM> described with reference to <FIG>. Therefore, a detailed description of the S201, S202, and S203 shown in <FIG> will be omitted.

Fourth, when the user's ear contacts the front surface of the display device <NUM> by the touch sensing device <NUM>, the main processor <NUM> determines whether the contact area of the user's ear is less than or equal to the first area A1 as shown in <FIG>. The main processor <NUM> may analyze touch data TD to determine the contact area of the user's ear. For example, the main processor <NUM> may calculate the touch area according to the number of touch cells sensed by the user.

Since the contact area of the user's ear increases as the pressure of the user pressing the front surface of the display device <NUM> increases, when the contact area of the user's ear is equal to or less than the first area A1, the main processor <NUM> may determine that the user's ear presses the front surface of the display device <NUM> at a pressure lower than the first pressure. Therefore, when the contact area of the user's ear is equal to or less than the first area A1, the main processor <NUM> controls the sound output of the first sound generator <NUM> to the second operating mode (S204 in <FIG>).

A step S205 shown in <FIG> is substantially same as a step S105 shown in <FIG>. Therefore, brief explanation regarding the step S205 is omitted.

Sixth, when the user's ear is in contact with the front surface of the display device <NUM> by the touch sensing device <NUM>, the main processor <NUM> determines whether the contact area of the user's ear is larger than the first area A1 as shown in <FIG>, and is less than or equal to the second area A2 as shown in <FIG>.

Since the contact area of the user's ear increases as the pressure of the user pressing the front surface of the display device <NUM> increases, when the contact area of the user's ear is larger than the first area A1 and is less than or equal to the second area A2, the main processor <NUM> may determine that the user's ear presses the front surface of the display device <NUM> with a pressure higher than the first pressure and lower than the second pressure. Therefore, when the contact area of the user's ear is larger than the first area A1 and smaller than the second area A2, the main processor <NUM> controls the sound output of the first sound generator <NUM> to the third operating mode. Further, when the contact area of the user's ear is larger than the second area A2, the main processor <NUM> controls the sound output of the first sound generator <NUM> to the fourth operating mode (S206 in <FIG>).

S207 shown in <FIG> are substantially the same as S107 described with reference to <FIG>. Therefore, a detailed description of the S207 shown in <FIG> will be omitted.

As described above, in the display device <NUM> according to the driving method shown in <FIG>, the first sound data SD1 and the second sound data SD2 are modulated in consideration of whether the user's ear contacts the front surface of the display device <NUM> and the pressure of the user's ear pressing the front surface of the display device <NUM>, thereby increasing and decreasing the sound pressure level for each frequency range. Therefore, since the sound pressure level can be uniformly maintained in a low-frequency range, a middle-frequency range, and a high-frequency range regardless of whether the user's ear contacts the front surface of the display device <NUM> and the pressure of the user's ear pressing the front surface of the display device <NUM>, high-quality sound can be provided.

Claim 1:
A display device (<NUM>), comprising:
a display panel (<NUM>) configured to display an image;
a touch sensing device (<NUM>) configured to sense a touch of an object;
wherein the display device (<NUM>) is in a first operating mode in response to the touch sensing device (<NUM>) not sensing the touch of the object, and
the display device (<NUM>) is in a second operating mode in response to the touch sensing device (<NUM>) sensing the touch of the object,
a sound driver configured to generate and transmit a first sound driving signal and a second sound driving signal according to first sound data (SD1) and second sound data (SD2);
a sound generator (<NUM>) configured to generate a sound according to the first sound driving signal and the second sound driving signal applied to a corresponding first pad and second pad of the sound generator (<NUM>); and
a main processor (<NUM>) comprising a digital signal processor (<NUM>);
characterized in that
the digital signal processor (<NUM>) is configured to modulate the first sound data (SD1) and the second sound data (SD2) for each of a first frequency range (FR1), a second frequency range (FR2), and a third frequency range (FR3),
the second frequency range (FR2) being higher than the first frequency range (FR1), and the third frequency range (FR3) being higher than the second frequency range (FR2) such that a sound pressure level in the first frequency range (FR1) is between a first sound pressure level (SPL1) and a second sound pressure level (SPL2) in both the first operating mode and the second operating mode,
the main processor (<NUM>) being configured to increase the sound pressure level in the first frequency range (FR1) to be higher than a third sound pressure level (SPL3), the third sound pressure level (SPL3) being higher than the first sound pressure level (SPL1), and to decrease the sound pressure level in the second frequency range (FR2) and the third frequency range (FR3), when the display device (<NUM>) transitions from the second operating mode to the first operating mode;
the increase or the decrease of the sound pressure level in each frequency range being determined based on a maximum value of the sound pressure level in each frequency range (FR1, FR2).