Patent Description:
Display devices are used as output devices for visually presenting image data, and are used in various areas such as homes and businesses.

Display devices may be implemented in various manners. For example, some displays control transmission of light emitted by a backlight unit through a panel, and other displays directly emit light. The displays that directly emit light may include an organic light emitting diode display that uses organic materials based on an electroluminiscence effect by which a fluorescent organic compound emits light when a current is applied to the fluorescent organic compound, and an inorganic light emitting diode display using inorganic compounds.

The inorganic light emitting diode display has light emitting diodes (LEDs) directly display image data based on a voltage applied across terminals of each LED. When a difference in voltage between both terminals of the LED is greater than a reference voltage, the LED emits light.

An LED display may steadily perform a discharging operation to control a voltage at an anode of the LED terminals by discharging a capacitor connected in parallel with the LED terminals and a precharging operation to control a voltage at a cathode of the LED terminals by charging the capacitor at all light emitting levels.

In this case, when input image data is a low grayscale image value, such as a black image, a voltage may be applied across the LED terminals according to the steady discharging and charging operations. When such a voltage is continuously applied, the LED may be stressed and thus the lifespan of the LED may be shortened.

<CIT> discloses an example prior art driving system for eliminating problems associated with shortened OLED lifetime caused by a long term DC bias lighting state. <CIT> discloses an electroluminescent display which provides reverse bias to an LED in order to reduce a level of photoluminescence.

Provided are a display device and control method thereof, which controls the magnitude of a voltage applied to an LED based on an input signal, thereby reducing the stress on the LED and increasing the lifespan of the LED.

In accordance with an aspect of the disclosure, a display device includes a light emitting diode (LED) module including a plurality of LEDs arranged in rows and columns as a passive matrix; a plurality of driving integrated chips (ICs), each of the plurality of driving ICs being configured to apply a voltage to cathodes of a corresponding column of the plurality of LEDs; a timing controller configured to apply a voltage to anodes of a corresponding row of the plurality of LEDs so as to drive light emission when a difference between the anodes and cathodes is greater than a preset voltage; and a controller configured to identify a first voltage to be applied across a first LED in operation, corresponding to an emission level of the first LED based on image data, compare the first voltage with a preset reference value, control a first driving IC, from among the plurality of driving ICs, that corresponds to the first LED to supply a driving voltage to the cathode of the first LED; wherein when the first voltage is equal to or greater than the preset reference value, the driving voltage is the first voltage, anc when the first voltage is less than the preset reference value, the driving voltage is a second voltage which is a preset voltage not changed depending on the image data and corresponding to a forward voltage of the first LED for preventing a reverse voltage across the first LED.

The controller may be further configured to identify the first LED driving voltage based on whether the first voltage is equal to or less than the reference value.

The controller may be further configured to identify, based on the image data, a second LED, from among the plurality of LEDs, to be driven by the second voltage.

Each of the plurality of driving ICs is further configured to control a cathode voltage of the corresponding group of the plurality of LEDs, and the controller is further configured to control an anode voltage of the plurality of LEDs and control the plurality of driving ICs.

The controller is further configured to control the anode voltage of the plurality of LEDs based on the second voltage.

The controller may be further configured to identify a driving IC to control the cathode voltage of the first LED, from among the plurality of driving ICs, based on the image data, and cease control of the anode voltage of the first LED while controlling the cathode voltage of the first LED using the driving IC.

The controller may be further configured to identify the first LED driving voltage as the second voltage based on a screen off signal.

The LED module may be one from among a plurality of LED modules provided in an LED module array, and the controller may be further configured to identify a black LED module, from among the plurality of LED modules, based on the image data indicating driving voltages of each LED of the black LED module as being below the reference value, and apply the second voltage to LEDs of the black LED module.

The controller may be further configured to generate a control signal to drive the first driving IC.

According to an aspect of the disclosure, a method of driving a display device, includes: receiving image data; determining a first LED driving voltage from among the LEDs based on analysis of the image data and a reference value; and controlling the driving IC to supply the first LED driving voltage.

The identifying includes identifying a first voltage corresponding to the first LED based on the image data; identifying the first voltage as the first driving voltage based on the first voltage being greater than the reference value; and identifying a second voltage as the first LED driving voltage based on the first voltage being equal to or less than the reference value.

The identifying may include identifying, based on the image data, a second LED, from among the plurality of LEDs, to be driven by the second voltage.

The controlling includes controlling an anode voltage of the first LED; and controlling the driving IC to control a cathode voltage of the LED.

The controlling of the anode voltage may include controlling the anode voltage to a preset voltage.

The controlling may include: identifying to control the cathode voltage of the first LED based on the image data; and ceasing control of the anode voltage of the first LED while controlling the driving IC.

The identifying may include identifying a second voltage as the first LED driving voltage to be applied to the first LED based on a screen off signal.

The LEDs may be included in an LED module that is one from among a plurality of LED modules provided in an LED module array, and the controlling may include: identifying a black LED module, from among the plurality of LED modules, based on the image data indicating driving voltages of each LED of the black LED module as being below the reference value; and applying a second voltage to LEDs of the black LED module.

The controlling may include generating a control signal to drive the driving IC based on the first LED driving voltage.

According to an aspect of the disclosure, a display device includes: a plurality of light emitting diodes (LEDs); a driving integrated circuit; and a timing controller. The timing controller is configured to: identify a first voltage based on image data corresponding to a first LED from among the plurality of LEDs; compare the first voltage with a reference voltage; identify the first voltage as a first LED driving voltage based on the first voltage exceeding the reference voltage; identify a preset voltage as the first LED driving voltage based on the first voltage being less than or equal to the reference voltage; and control the first LED and the driving integrated circuit based on the first LED driving voltage.

The timing controller may be further configured to identify a driving voltage for each of the plurality of LEDs based on a comparison of the reference voltage and a corresponding voltage, from among a plurality of voltages, identified based on the image data.

The timing controller may be further connected to an anode of the first LED and the driving integrated circuit is connected to a cathode of the first LED.

According to an aspect of the disclosure, a non-transitory computer readable recording medium having embodied thereon a program, which when executed by a processor of a display device, causes the display device to execute a method, the method including: identifying a first voltage based on image data corresponding to a first LED from among a plurality of LEDs; comparing the first voltage with a reference voltage; identifying the first voltage as a first LED driving voltage based on the first voltage exceeding the reference voltage; identifying a preset voltage as the first LED driving voltage based on the first voltage being less than or equal to the reference voltage; and controlling the first LED based on the first LED driving voltage.

The above and other aspects, features and advantages of certain embodiments of the present disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:.

Embodiments will now be described with reference to accompanying drawings.

Accordingly, various changes, modifications, and equivalents of the methods, apparatuses, and/or systems described herein and falling within the appended claims will be suggested to those of ordinary skill in the art. The progression of processing operations described is an example; however, the sequence of and/or operations is not limited to that set forth herein and may be changed as is known in the art, with the exception of operations necessarily occurring in a particular order. In addition, respective descriptions of well-known functions and constructions may be omitted for increased clarity and conciseness.

Additionally, embodiments will now be described more fully hereinafter with reference to the accompanying drawings. The embodiments may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete and will fully convey the exemplary embodiments to those of ordinary skill in the art. Like numerals denote like elements throughout.

It will be understood that when an element is referred to as being "connected," or "coupled," to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected," or "directly coupled," to another element, there are no intervening elements present.

Reference will now be made in detail to the exemplary embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.

The expression, "at least one of a, b, and c," should be understood as including only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.

<FIG> is an exterior view of a display system, according to an embodiment. <FIG> shows a schematic arrangement and signal flows in a display system, according to an embodiment.

Referring to <FIG> and <FIG>, a display system <NUM> may include a display device <NUM> that visually presents an image and an image reproducing device <NUM> that provides image data to the display device <NUM>.

The display system <NUM> may be used as a big screen in theaters, as a general display device, such as in televisions (TVs) and monitors, or for a large billboard. The display system <NUM> may installed outdoors, e.g., on the rooftop of a building or at a bus stop. However, the display system <NUM> may be installed indoors, e.g., at subway stations, shopping malls, theaters, offices, stores, etc..

The display device <NUM> may include a plurality of light emitting diode (LED) module arrays <NUM>. Each LED module array <NUM> may include LEDs to provide a particular resolution. When a relatively large pitch size is provided between the LEDs, the display device <NUM> may be used for an information transferring device, such as a large billboard. On the contrary, when a relatively small pitch size, such as on the scale of micrometers (µm), is provided between the LEDs, the display device <NUM> may be used for a high resolution screen in a theater as well as TVs.

The plurality of LED module arrays <NUM> may be arranged in rows and columns. In other words, the LED module arrays <NUM> may be arranged in the form of a matrix, for example, in a <NUM> x <NUM> matrix with <NUM> columns and six rows.

The plurality of LED module arrays <NUM> arranged in a matrix may be integrated into a single screen S. The integrated LED module arrays <NUM> may be controlled to display an image.

Each LED in the plurality of LED module arrays <NUM> may correspond to a unit pixel P, and an image may be formed by a combination of light emitted from the plurality of pixels P. For example, the plurality of pixels P may emit light with various brightnesses and colors, and the light emitted by the plurality of pixels P may be combined into an image that may be perceived by a viewer.

The screen S may include a variable number of LEDs corresponding to various resolutions. For example, to have <NUM> resolution according to Digital Cinema Initiatives (DCI), the screen S may include <NUM> x <NUM> LEDs. In another example, to have <NUM> ultra high definition (UHD) resolution according to the International Telecommunication Union (ITU), the screen S may include <NUM> x <NUM> LEDs. Specifically, when each unit pixel P of the screen S having the <NUM> resolution includes a red LED, a blue LED, and a green LED, the number of LEDs corresponding to the <NUM> resolution may be <NUM> x <NUM> x <NUM> or <NUM> x <NUM> x <NUM>. When each LED corresponding to the unit pixel P is a single LED chip, which is an encapsulation of red, blue, and green LEDs, the number of LEDs corresponding to the <NUM> resolution may be <NUM> x <NUM> or <NUM> x <NUM>.

The image reproducing device <NUM> may store content, such as a video, or may receive the content from an external content source (e.g., a video streaming service server). For example, the image reproducing device <NUM> may store a file of content data in a storage, or receive content data from the external content source in real time.

The image reproducing device <NUM> may decode the stored or received content data into image frame data (hereinafter, image data). For example, a broadcast signal or content data may be compressed according to various video compression standards, such as Moving Picture Experts Group (MPEG), High Efficiency Video Coding (HEVC), etc. The image reproducing device <NUM> may restore the image data representing each image frame from the compressed content data.

The image reproducing device <NUM> may send the restored image data to the display device <NUM>.

Referring to <FIG>, there may be image data lines, such as image data line L1, between the image reproducing device <NUM> and the plurality of LED module arrays <NUM>, 100a, 100b, and the image reproducing device <NUM> may send the image frame data to the plurality of LED module arrays <NUM>, 100a, 100b through the image data lines. <FIG> illustrates a single image data line L1. However, embodiments are not limited thereto, and one or more embodiments may include additional image data lines to connect LED module arrays to the image reproducing device <NUM>.

The plurality of LED module arrays <NUM>, 100a, 100b may also receive image frame data from the image reproducing device <NUM> through the image data lines, and display an image corresponding to the received image data.

Upon reception of the image data, the plurality of LED module arrays <NUM>, 100a, 100b may each display a portion of an image to be displayed on the entire screen S. Specifically, each of the plurality of LED module arrays <NUM>, 100a, 100b may occupy a certain area on the screen S and output a portion of the entire image corresponding to where the LED module array is arranged.

For example, the image reproducing device <NUM> may send image data of the entire image to each of the plurality of LED module arrays <NUM>, 100a, 100b, which may in turn extract portions of the image data of the entire image corresponding to the location of the particular LED module array, and display images corresponding to the image data that is extracted according to the locations of the LED module arrays <NUM>, 100a, 100b. In another example, the image reproducing device <NUM> may divide the image data into a plurality of sub image frame data and send the plurality of sub image frame data to corresponding LED module arrays <NUM>, 100a, 100b, each of which may, in turn, display an image corresponding to the sub image frame data.

<FIG> is a front view of an LED module array, according to an embodiment. <FIG> is a rear view of an LED module array, according to an embodiment. <FIG> is an exploded view of an LED module array, according to an embodiment.

Referring to <FIG>, <FIG>, and <FIG>, a cabinet <NUM> of the LED module array <NUM> may include constituent parts to display an image I on the screen S.

The LED module array <NUM> may include LED modules <NUM> to emit light in the forward direction to generate an image, a control assembly <NUM> to control the LED modules <NUM>, a power assembly <NUM> to supply power to the LED modules <NUM> and the control assembly <NUM>, and a chassis <NUM> to support/fix LED modules <NUM>, the control assembly <NUM> and the power assembly <NUM>.

There may be a plurality of LED modules <NUM> in the LED module array <NUM>. In an embodiment, the LED module array <NUM> may include multiple LED modules <NUM> arranged in a <NUM> x <NUM> matrix. The LED module array <NUM> is not, however, limited thereto, and the number and arrangement of the LED modules may be variously modified.

The LED module <NUM> may include a plurality of LEDs <NUM> mounted on a module substrate 104c, and the plurality of LEDs <NUM> are arranged in the form of a matrix.

The LED <NUM> is a semiconductor device that emits light with preset wavelength when power is supplied thereto. Similar to the normal diode, the LED <NUM> has also polarities, the anode and the cathode, and emits light when a voltage across the anode and the cathode is equal to or greater than a preset level.

The plurality of LEDs <NUM> may emit light with different colors and different brightnesses. In an embodiment, the LED <NUM> may emit light with different wavelengths (different colors) depending on the constituent material. For example, when the LED <NUM> includes aluminum gallium arsenide (AlGaAs), gallium arsenide phosphide (GaAsP), gallium phosphide (GaP), etc., the LED <NUM> may emit red light of about <NUM> to about <NUM>; when the LED <NUM> includes indium gallium nitride (InGaN), the LED <NUM> may emit green light of about <NUM> to about <NUM>; when the LED <NUM> includes gallium nitride (GaN), the LED <NUM> may emit blue light ray about <NUM> to about <NUM>. The LED <NUM> may emit various wavelengths of light such as white light other than the aforementioned wavelengths.

The plurality of LEDs <NUM> may include red LEDs that embody red sub pixels (PRs), green LEDs that embody green sub pixels (PGs), and blue LEDs that embody blue sub pixels (PBs). A red LED, a green LED, and a blue LED may be integrated into the single pixel P, and may be repeatedly arranged.

Furthermore, the plurality of LEDs <NUM> may emit light with different intensities depending on the magnitude of a current applied. For example, as the current applied increases, the plurality of LEDs <NUM> may emit light with higher intensities.

An image may be formed by a combination of light emitted from the plurality of LEDs <NUM>. For example, an image may be formed by a combination of red light emitted from red LEDs, green light emitted from green LEDs, and blue light emitted from blue LEDs.

The control assembly <NUM> may include a timing controller (TCON) and other various control circuits for controlling operation of the LED module <NUM>.

The timing controller (see <FIG>) may process an image signal into image data, and control a plurality of driving integrated chips (ICs) (see <FIG>) and LEDs mounted on the module substrate 104c. The driving IC is a semiconductor that converts control image data into an analog value to directly drive an LED. The control image data may be based on a digital signal. The timing controller and driving ICs will be described later in more detail in connection with other drawings.

The power assembly <NUM> supplies stable power to the LED modules <NUM> in order for the plurality of LEDs <NUM> to emit light with different colors and different brightnesses. For example, the power assembly <NUM> may include a switching mode power supply (SMPS) for supplying power to the control assembly <NUM> and driving ICs by switching operations.

The control assembly <NUM> and the power assembly <NUM> may be implemented with printed circuit boards (PCBs) and various circuits mounted on the PCBs. For example, a power circuit may include a power circuit board, and a capacitor, a coil, a resistor, a microprocessor, etc., which are mounted on the power circuit board. The timing controller may also include a control circuit board, and a memory and a microprocessor mounted on the control circuit board.

The cabinet <NUM> may include a front bracket 101a, a frame bracket <NUM>, and a rear cover <NUM>, and the front bracket 101a, the frame bracket <NUM>, and the rear cover <NUM> may support and accommodate the LED modules <NUM>, the control assembly <NUM>, and the power assembly <NUM>.

The front bracket 101a may support the LED modules <NUM>. The frame bracket <NUM> may be located on the rear surface of the front bracket 101a to accommodate the control assembly <NUM> and the power assembly <NUM>. The rear cover <NUM> may be detachably connected to the frame bracket <NUM> to provide access to the cabinet <NUM>.

The chassis <NUM> may support the control assembly <NUM> and the power assembly <NUM>. For example, the control assembly <NUM> and the power assembly <NUM> may be fixed to the chassis <NUM>, and the chassis <NUM> may be fixed to the rear surface of the front bracket 101a.

The mechanical structure of the LED module array <NUM> is not, however, limited to the aforementioned descriptions and drawings. For example, it is enough for the LED module array <NUM> to include the plurality of LED modules <NUM>, the control assembly <NUM> for controlling the LED modules <NUM>, and the power assembly <NUM>, and other components may be optionally included in the LED module array <NUM>.

<FIG> is a control block diagram of a display device, according to an embodiment. <FIG> schematically shows a rear surface of an LED module, according to an embodiment. <FIG> represents an area of an LED module according to an embodiment. As shown, the LED module includes control blocks. The embodiment will be described in connection with <FIG> together to avoid overlapping explanation.

Referring to <FIG>, the display device <NUM> may include a user input device <NUM> for receiving a user input from the user, a content receiver <NUM> for receiving a video signal and/or an audio signal (or collectively, an image signal) from content sources, an image display <NUM> for displaying an image, a communicator <NUM> for communicating with external devices, a sound output device <NUM> for outputting sound, a data storage <NUM> for storing various programs and data, and a controller <NUM> for controlling operations of the display device <NUM>.

The user input device <NUM> may include an input button <NUM> for receiving a user input, and a signal receiver <NUM> for receiving a remote control signal from a remote controller. For example, the user input device <NUM> may include a power button for soft turn-on (operation start) or soft turn-off (operation stop) of the display device <NUM>, a sound control button to control sound volume output by the display device <NUM>, a source selection button to select a content source, etc..

The input button <NUM> may receive a user input, generate an electric signal corresponding to the user input, and send the electric signal to the controller <NUM>. The input button <NUM> may be implemented with various input devices such as a push switch, a touch switch, a dial, a slide switch, a toggle switch, etc..

The remote controller may be provided separately from the display device <NUM>, and may receive a user input and send a radio signal corresponding to the user input to the display device <NUM>. The signal receiver <NUM> may receive a radio signal corresponding to a user input from the remote controller, generate an electric signal corresponding to the user input, and send the electric signal to the controller <NUM>.

The content receiver <NUM> may include receiving terminal <NUM> and a tuner <NUM> for receiving an image signal including a video signal and/or an audio signal from the content sources. According to one or more embodiments, the content receiver <NUM> may include a plurality of receiving terminals <NUM>.

The receiving terminals <NUM> may receive a video signal and an audio signal from the content sources through a cable. For example, the receiving terminals <NUM> may include a component (YPbPr/RGB) terminal, a composite video blacking and sync (CVBS) terminal, an audio terminal, a high definition multimedia interface (HDMI) terminal, a universal serial bus (USB) terminal, etc..

The tuner <NUM> may receive broadcast signals through an antenna or a cable, and extract a broadcast signal corresponding to a channel selected by the user among the received broadcast signals. For example, the tuner <NUM> may pass a broadcast signal having a frequency corresponding to a channel selected by the user among the plurality of broadcast signals received through the antenna or the cable, and block other broadcast signals having different frequencies.

As such, the content receiver <NUM> may receive an image signal from the content sources through the receiving terminal <NUM> and/or the tuner <NUM>, and send the image signal to the controller <NUM>. The controller <NUM> may analyze/process the image signal and then convert the image signal to image data, as will be described later.

The image display <NUM> includes driving ICs <NUM> for converting image data to an analog signal, and the plurality of LEDs <NUM> driven by the driving ICs <NUM>.

In an embodiment, the LED module <NUM> may include <NUM> x <NUM> driving ICs <NUM>. Referring to <FIG>, first to 40th driving ICs <NUM>-<NUM> to <NUM>-<NUM> may be mounted on the PCB provided on the rear surface of the LED module <NUM>.

Referring to <FIG>, the first driving IC <NUM>-<NUM> of a first column may control a first line of LEDs <NUM> including <NUM> x <NUM> LEDs <NUM>. Specifically, the first driving IC <NUM>-<NUM> may apply a voltage to the cathode of LEDs <NUM> included in the first line through output lines RO to R15. The second driving IC <NUM>-<NUM> may apply a voltage to the cathode of LEDs <NUM> included in the second line through output lines R16 to R31. The tenth driving IC <NUM>-<NUM> may apply a voltage to the cathode of LEDs <NUM> included in the tenth line through output lines R144 to R159.

The timing controller <NUM> may apply a voltage to anodes of the LEDs <NUM> through output lines CO through C29. A voltage applied to the anode of the LEDs <NUM> included in each line may be determined by the timing controller <NUM> arranged in the control assembly <NUM>. The anode of the LEDs <NUM> is connected to the timing controller <NUM>, and the cathode of the LEDs <NUM> is connected to the driving ICs <NUM>.

The timing controller <NUM> determines a voltage to be applied to the anode of the LEDs <NUM> included in each line while controlling the driving ICs <NUM> based on the analyzed image data. When a difference in voltage between the anode of the LED <NUM> and the cathode of the LED <NUM> applied by the driving IC <NUM> is equal to or greater than a preset voltage, the LED <NUM> emits light.

The function of the driving IC <NUM> controlling the voltage applied to the cathode of the LEDs <NUM> included in each line is a charging operation, and the function of the timing controller <NUM> controlling the voltage applied to the anode of the LEDs <NUM> included in the LED module <NUM> is a discharging operation. The display device <NUM> may attain enhanced image quality by controlling the voltage at the cathode using the driving ICs <NUM>.

A criterion for controlling voltages at both terminals of the LED <NUM> may take diode and circuit characteristics into account. Specifically, when the charging and discharging operations are performed by taking into account the circuit characteristics, a reverse voltage may occur across the LED <NUM> when image data including a black image or low gray scale image value is input. Hence, after analyzing the image data, the display device <NUM> applies a new voltage that reduces stress to some LEDs <NUM> across which the reverse voltage is likely to occur. This will be described later in more detail with reference to other drawings.

The aforementioned operations of the driving IC <NUM> and the timing controller <NUM> correspond to a passive matrix (PM) driving method for controlling the LEDs <NUM> line by line. However, embodiments not forming part of the claimed invention are not limited to the PM driving method, and an active matrix (AM) driving method may be used by the display device <NUM> for controlling the LEDs <NUM> individually. Specifically, when employing the AM driving method, the display device <NUM> may include driving ICs for driving LEDs individually, the number of LEDs being preset according to a resolution, and a controller for analyzing received image data to determine a first voltage for the LED to emit light, determining a second voltage applied to the LED based on the first voltage and a reference value, and controlling the driving IC based on the second voltage.

The communicator <NUM> may exchange data with external devices other than the display device <NUM>. For example, the communicator <NUM> may exchange data with a user equipment or other electronic devices.

The wired communication interface <NUM> may access a wired communication network and communicate with an external device over the wired communication network. For example, the wired communication interface <NUM> may access a wired communication network through Ethernet, the IEEE <NUM> technology standard, and receive data from external devices over the wired communication network.

The wireless communication interface <NUM> may communicate wirelessly with a base station or an access point (AP), and access the wired communication network via the base station or the AP. The wireless communication interface <NUM> may communicate with external devices connected to the wired communication network via the base station or the AP. For example, the wireless communication interface <NUM> may use WiFi™, the IEEE <NUM> technology standard, to communicate with an AP, or use code divisional multiple access (CDMA), wideband code division multiple access (WCDMA), Global Systems for Mobile communications (GSM), Long Term Evolution (LTE), WiBro, etc., to communicate with a base station. The wireless communication interface <NUM> may receive data from the external devices via the base station or the AP.

In addition, the wireless communication interface <NUM> may communicate directly with the external device, such as a UE. For example, the wireless communication interface <NUM> may use Wireless Fidelity (Wi-Fi), Bluetooth™ which is the IEEE <NUM>. <NUM> technology standard, ZigBee™, which is the IEEE <NUM>. <NUM> technology standard, etc., to wirelessly receive data directly from the external device.

The sound output device <NUM> may include a speaker <NUM> for outputting sound in an audible signal or sound waves.

The speaker <NUM> may convert an analog sound signal amplified by an amplifier to a sound or sound waves. For example, the speaker <NUM> may include a thin film that vibrates according to an electric sound signal, and the vibration of the thin film may generate sound waves.

The data storage <NUM> may include a storage medium for storing a program and data for controlling the operation of the display device <NUM>. The program may include a plurality of instructions containing a code made by a compiler or a code executable by an interpreter, which when executed by a processor of the display device, control the display to device to perform a particular function, and the data may be processed according to the plurality of instructions included in the program.

The storage medium <NUM> may store content data in a file format. For example, the storage medium <NUM> may store the content data in the form of "*. asf", or "*. mp4" file, and provide the content data to the controller <NUM> in response to a readout instruction from the controller <NUM>.

For example, the storage medium <NUM> may store an image signal input from the content receiver <NUM> and/or the communicator <NUM>, and provide the stored image signal for the controller <NUM> to process image data. In another example, the storage medium <NUM> may receive and store the image data processed by the controller <NUM>.

The storage medium <NUM> may store the program and/or data electrically, magnetically, or optically. For example, the storage medium <NUM> may include a solid state drive (SSD), a hard disc drive (HDD), an optical disc drive (ODD), or the like.

The controller <NUM> may include one or more memories <NUM> for memorizing/storing a program/data, and one or more processors <NUM> for processing the data according to the program. The controller <NUM> may include hardware, such as the memory <NUM> and the processor <NUM>, and software, such as the program and/or data memorized/stored in the memory <NUM> and/or the data storage <NUM>.

The memory <NUM> may store a program and data for controlling the components included in the display device <NUM>. For example, the memory <NUM> may store instructions that contain a code made by a compiler or a code executable by an interpreter to be executed by processor <NUM>.

The memory <NUM> may temporarily store data provided from the components of the display device <NUM>. For example, the memory <NUM> may store a user input received through the user input device <NUM>, image data received through the content receiver <NUM>, communication data received through the communicator <NUM>, data stored in the data storage <NUM>, etc..

The memory <NUM> may include a non-volatile memory, such as a Read Only Memory (ROM), a flash memory, and/or the like, which may store data for a long period, and a volatile memory, such as a static random access memory (SRAM), a dynamic RAM (DRAM), or the like, which may temporarily store data.

The processor <NUM> processes the data stored in the memory <NUM> according to the program (or a series of programs) stored in the memory <NUM>. For example, the processor <NUM> may process the user input, the image data, the communication data, the stored data, etc., according to the program stored in the memory <NUM>. Furthermore, the processor <NUM> may generate a control signal to control at least one of the image display <NUM>, the communicator <NUM>, or the data storage <NUM> based on a result of processing the data.

The processor <NUM> may include an operation circuit for performing a logic operation and an arithmetic operation, and a memory circuit for storing the data resulting from the operation.

As such, the controller <NUM> may process the data obtained from the components included in the display device <NUM> and control the components.

Specifically, the controller <NUM> may control operations of the display device <NUM> based on user inputs received through the user input device <NUM>. For example, the controller <NUM> may supply power to the image display <NUM> and send the processed image data to the image display <NUM>, in response to a user input to initiate operation (turn-on operation). Furthermore, the controller <NUM> may stop sending the image data to the image display <NUM> and block the power to the image display <NUM>, in response to a user input to stop operation (turn-off operation).

The controller <NUM> may analyze an image signal (a TV broadcast signal, streaming data, etc.) received through the content receiver <NUM> or stored in the data storage <NUM> and convert the image signal to image frame data (hereinafter, image data). For example, the controller <NUM> may obtain a compressed/encoded image signal from the content receiver <NUM> and/or the data storage <NUM>, and decode the compressed/encoded image signal to image data.

The controller <NUM> analyzes the image data, and then determine an LED <NUM> to emit light and a particular voltage value for the LED <NUM> to emit light based on the image data. The controller <NUM> determines a voltage (hereinafter, a first voltage) for the LED <NUM> based on the particular voltage value and then outputs a control signal corresponding to the first voltage to the driving IC <NUM>. The image display <NUM> applies a voltage to the LED <NUM> to control light emission according to the control signal from the controller <NUM>.

The controller <NUM> compares the first voltage determined by analyzing the image data with a preset reference value to determine whether to control the image display <NUM> at the first voltage. When the image data is a black image or includes a low grayscale that is less than a reference value, the controller <NUM> controls the display <NUM> at a preset voltage (hereinafter, a second voltage) instead of the first voltage. This enables the controller <NUM> to reduce the stress on some of the LEDs <NUM> displaying image data in the LED module <NUM> or in the LED module array <NUM> and prevent LED damage and line defect, which will be described later.

The processor <NUM> and the memory <NUM> may be implemented separately with a plurality of semiconductor devices or integrated in a single semiconductor device.

The timing controller <NUM> as described above in connection with <FIG> may be an example of the controller <NUM>. In another embodiment, the timing controller <NUM> may be provided in each LED module <NUM> included in the display device <NUM>. In this case where the timing controller <NUM> is provided in the plural, a separate processor may be provided to analyze image data and collectively control the respective timing controllers <NUM>.

The display device <NUM> may further include a component for performing an additional function in addition to the aforementioned components as shown in <FIG>, or may leave out one or more of the aforementioned components, as needed.

<FIG> is a depiction for explaining a possible problem occurring in a display device.

In the display device <NUM>, the controller <NUM> analyzes an image signal and controls the LED <NUM> emit light based on the analyzed image data. The display device <NUM> may control the voltage across both terminals of the LED <NUM> by the aforementioned discharging and charging operations. Such voltage control may be determined by taking into account characteristics of the LED <NUM> and associated circuits.

However, image data in some areas of the image I displayed on the display device <NUM> may have a voltage that is less than a certain level. Specifically, when the display device <NUM> includes the plurality of LED module arrays <NUM>, some LED module arrays <NUM> located at either edge of the image I may output the black image. Furthermore, some of the continuously displayed images I may include black content on the entire screen.

Even when displaying the image data that is a black image, a related device performs steady discharging and charging operations, which may lead to a reverse voltage across the LED <NUM>. The reverse voltage applied across the LED <NUM> causes stress. When the reverse voltage is continuously applied, the LED <NUM> has a continuous stress. Continuous stress may damage the LED <NUM>, causing a vertical line corresponding to the damaged LEDs <NUM>, for example line defect (<NUM>-<NUM>) as shown in <FIG>, to appear on the display device <NUM>. The line defect causes the LEDs to emit a large amount of light, and is noticeably visible in the black image or a low grayscale image. For example, the line defect occur in sub pixels of a certain color, and the line defect may appear in a corresponding color.

In order to reduce the stress on the LED <NUM> and prevent the line defect, the display device <NUM> identifies image data that has a grayscale lower than a preset reference value and applies the preset second voltage to the LED <NUM> driven to emit light for the identified image data.

<FIG> is a flowchart illustrating a control method of a display device, according to an embodiment.

For example, the controller <NUM> may control the display device <NUM> to perform the control method illustrated in <FIG>.

Referring to <FIG>, the controller <NUM> receives an image signal, in operation <NUM>. Specifically, the image signal received by the display device <NUM> may have various types, and for example, the image signal may be movie streaming data.

The controller <NUM> analyzes the image signal to determine a first voltage corresponding to the LED <NUM> in operation <NUM>.

Specifically, the controller <NUM> may determine LEDs <NUM> included in the LED module <NUM> or the LED module array <NUM> in each frame of the image data, and determine an emission level of an LED <NUM> to emit light. As described above, the emission level of the LED <NUM> may be determined based on the voltage, and the voltage may be determined from the image data.

The controller <NUM> determines whether the image data includes a black image, in operation <NUM>.

Of multiple frames corresponding to the image data, some frames may include the black image.

When the image data is the black image, the controller <NUM> changes the voltage applied to all the LEDs <NUM> included in the LED module <NUM> or the LED module array <NUM> to the second voltage, in operation <NUM>. The controller <NUM> generates a control signal based on the second voltage, and controls the driving IC <NUM>, in operation <NUM>.

The second voltage is preset, and corresponds to a forward voltage of the LED <NUM>. By applying the second voltage, stress that may be imposed on the LED <NUM> due to a reverse voltage across the LED <NUM> may be reduced. The value of the second voltage is not changed depending on the image data. For example, the second voltage may have a value set by the manufacturer of the display device <NUM> in a manufacturing stage.

Alternatively, the value of the second voltage may be changed by the user input device <NUM>.

When the image data is not the black image, the controller <NUM> compares the value of the first voltage and a preset reference value, in operation <NUM>.

Specifically, the value of the first voltage is determined by analyzing the image data. The first voltage may be different for each LED <NUM> included in the LED module <NUM> or the LED module array <NUM>. For example, even for one frame, the plurality of LEDs <NUM> may be divided into LEDs that display an image with content and LEDs that display a low grayscale image with no content. The LEDs that display a low grayscale image with no content may be usually located at edges of the screen S.

When the LEDs <NUM> emit light at a particular grayscale or less at the first voltage, the controller <NUM> changes the voltage to be applied to the LEDs <NUM> from the first voltage to the second voltage, in <NUM>. The controller <NUM> generates a control signal based on the second voltage, and controls the driving IC <NUM>, in operation <NUM>.

On the other hand, when it is determined that the LED <NUM> does not display the black image and emits light at the first voltage that exceeds the preset reference value, the controller <NUM> controls the driving IC <NUM> based on the first voltage, in operation <NUM>.

When the controller <NUM> controls the driving IC <NUM>, a control signal may drive multiple LEDs <NUM> on each line, which may correspond to the charging operation. On the other hand, the controller <NUM> may control emission of the LED <NUM> not only through the driving IC <NUM> but directly control the LED <NUM> based on the second voltage by performing the discharging operation. This will be described later in more detail with reference to <FIG> and <FIG>.

<FIG> is a flowchart illustrating a control method of a display device, according to another embodiment.

Referring to <FIG>, the controller <NUM> receives a screen off signal in operation <NUM>.

The screen off signal is a signal to prevent the LED <NUM> from emitting light, and may be used in a standby mode, a suspend mode, an off mode, etc., to minimize power consumption of the display device <NUM>. The screen off signal may be received through the user input device <NUM> or generated by the controller <NUM> when a certain condition is met.

The LED <NUM> does not emit light in response to the screen off signal. However, a reverse voltage may be applied across the LED <NUM> due to the aforementioned charging and discharging operations.

Accordingly, in the disclosure, the controller <NUM> controls the driving IC <NUM> at the second voltage according to the screen off signal, for example when the screen off signal is received through the user input device <NUM> or generated by the controller <NUM> when the condition is met, in operation <NUM>.

The display device <NUM> may apply the second voltage to the LED <NUM> based on various external signals other than the result of analysis of the image data, thereby reducing the stress and preventing damage to the LED <NUM>.

<FIG> and <FIG> are flowcharts illustrating control methods of a display device, according to embodiments.

Referring to <FIG>, the controller <NUM> determines to drive the LED <NUM> at the second voltage, in operation <NUM>.

As described above in connection with <FIG> and <FIG>, the controller <NUM> may determine to drive the LED <NUM> at the second voltage based on different reasons such as a result of analysis of the image data or the screen off signal. In this case, the controller <NUM> may control the LED <NUM> at the second voltage in the following two examples.

First, the controller <NUM> applies the second voltage to the LED <NUM> by controlling a voltage at the anode of the LED <NUM>, in operation <NUM>.

As described above in connection with <FIG>, when the timing controller <NUM> controls the voltage applied to the anode of the LED <NUM>, the controller <NUM> applies the second voltage to the LED <NUM> by directly performing the discharging operation.

Alternatively, the controller <NUM> may apply the second voltage to the LED <NUM> by controlling a voltage at the cathode of the LED <NUM> through the driving IC <NUM>. Referring to <FIG>, the controller <NUM> determines to drive the LED <NUM> at the second voltage, in operation <NUM>.

As described above in connection with <FIG>, the driving IC <NUM> may control the voltage at the cathode of the LED <NUM>. Accordingly, the controller <NUM> may apply the second voltage to the LED <NUM> by performing the charging operation through the driving IC <NUM>, in operation <NUM>.

Furthermore, the controller <NUM> stops controlling the voltage at the anode of the LED <NUM>, in operation <NUM>. For example, when the charging operation is used, the controller <NUM> may not perform the discharging operation that controls the voltage at the anode of the LED <NUM>.

However, it is also possible for the controller <NUM> to apply the second voltage to the LED <NUM> while performing the charging operation and discharging operation together without the need to separate the charging operation from the discharging operation all the time.

According to the embodiments, a display device and control method thereof can control the magnitude of a voltage applied to an LED based on an input signal, thereby reducing the stress on the LED and increasing the lifespan of the LED.

In addition, the display device and control method thereof can prevent a line defect from occurring due to steady stress on the LED.

Embodiments have been described above. In the embodiments, some components may be implemented as a "module". Here, the term 'module' indicates, but is not limited to, a software and/or hardware component, such as a Field Programmable Gate Array (FPGA) or Application Specific Integrated Circuit (ASIC), which performs certain tasks. A module may be configured to reside on the addressable storage medium and configured to execute on one or more processors.

Thus, a module may include, by way of example, components, such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. The operations provided for in the components and modules may be combined into fewer components and modules or further separated into additional components and modules. In addition, the components and modules may be implemented such that they execute one or more CPUs in a device.

Additionally, embodiments can also be implemented through computer readable code or instructions that are stored in or on a medium, e.g., a computer readable medium, to control at least one processing element to implement any above described exemplary embodiment. The medium can correspond to any medium/media permitting the storing and/or transmission of the computer readable code.

The computer-readable code can be recorded on a medium or transmitted through the Internet. The medium may include Read Only Memory (ROM), Random Access Memory (RAM), Compact Disk-Read Only Memories (CD-ROMs), magnetic tapes, floppy disks, and optical recording medium. Also, the medium may be a non-transitory computer-readable medium. The media may also be a distributed network, so that the computer readable code is stored or transferred and executed in a distributed fashion. Still further, as only an example, the processing element could include at least one processor or at least one computer processor, and processing elements may be distributed and/or included in a single device.

Claim 1:
A display device (<NUM>) comprising:
a light emitting diode 'LED' module (<NUM>) including a plurality of LEDs (<NUM>) arranged in rows and columns as a passive matrix;
a plurality of driving integrated chips 'ICs' (<NUM>), each of the plurality of driving ICs (<NUM>) being configured to apply a voltage to cathodes (<NUM>) of a corresponding column of the plurality of LEDs (<NUM>),
a timing controller (<NUM>) configured to apply a voltage to anodes of a corresponding row of the plurality of LEDs (<NUM>) so as to drive light emission when a difference in voltage between the anodes and cathodes (<NUM>) is greater than a preset voltage; and
a controller (<NUM>) configured to:
identify a first voltage to be applied across a first LED (<NUM>) in operation, from among the plurality of LEDs (<NUM>), corresponding to an emission level of the first LED (<NUM>) based on image data, compare the first voltage with a preset reference value, and control a first driving IC, from among the plurality of driving ICs (<NUM>), that corresponds to the first LED to supply a driving voltage to the cathode of the first LED,
wherein when the first voltage is equal to or greater than the preset reference value, the driving voltage is the first voltage, and when the first voltage is less than the preset reference value, the driving voltage is a second voltage which is a preset voltage not changed depending on the image data and corresponding to a forward voltage of the first LED (<NUM>) for preventing a reverse voltage across the first LED (<NUM>).