WO2023214686A1

WO2023214686A1 - Display apparatus and control method thereof

Info

Publication number: WO2023214686A1
Application number: PCT/KR2023/003873
Authority: WO
Inventors: 신승용; 강정모; 김창훈; 정용민
Original assignee: 삼성전자주식회사
Priority date: 2022-05-06
Filing date: 2023-03-23
Publication date: 2023-11-09
Also published as: KR20230156612A

Abstract

A display apparatus according to an embodiment may comprise: a light-emitting unit which includes a driving circuit for controlling a driving current; a monitoring unit which measures a forward voltage of at least one of light-emitting elements included in the light-emitting unit; and a control unit which determines an output voltage on the basis of the driving current and the forward voltage.

Description

Display device and its control method

The present invention relates to a display device and a control method thereof, and more particularly, to a display device that controls the driving voltage of a light emitting diode (LED) and a control method thereof.

A display device is an output device that converts electrical information into visual information and displays it to the user. Display devices may include not only televisions and monitors, but also portable devices such as notebook PCs, smart phones, and tablet PCs.

The display device may include a self-luminous display panel such as an organic light-emitting diode (OLED) or a light-receiving display panel such as a liquid crystal display (LCD).

A display device using a light-receiving display panel may include a backlight unit that provides light to the display panel. The backlight unit may include an edge-type in which the light source is disposed on at least one side of the display panel and a direct-type in which the light source is disposed behind the display panel.

According to consumer demands, display devices have come to use more light-emitting elements than before to achieve high performance (e.g., improved CR (Capability Ratio), reduced thickness, increased resolution, etc.).

In order to control all light-emitting elements included in a display device to the same brightness, not only must an appropriate output current be supplied, but the voltage of the light-emitting elements must also be appropriately supplied. However, the voltage (forward voltage) required to create the same brightness of all light-emitting devices has different problems.

To solve this problem, conventional display devices measure the forward voltage for each current of a plurality of light-emitting devices in advance in order to adjust the voltage supplied to the light-emitting devices, and then measure representative values (e.g., the largest voltage, the average After calculating the value, etc.), the voltage corresponding to the representative value for each current was supplied.

These conventional display devices have problems in that they supply a higher voltage than necessary to produce the same brightness of the light emitting elements, resulting in increased power consumption, or fail to provide the desired brightness (brightness) by failing to supply an appropriate voltage. Additionally, when the number of light-emitting elements included in a display device increases, there is a problem in that monitoring and supplying the required voltage of all light-emitting elements in the display device increases the complexity and cost of the system.

One aspect of the present disclosure is to prevent an increase in system complexity and cost and to provide a display device and a control method thereof that can determine an appropriate output voltage.

A display device according to an embodiment includes a light emitting unit including a driving circuit that controls a driving current, a monitoring unit that measures the forward voltage of at least one light emitting element among the light emitting elements included in the light emitting unit, and the driving current and the forward voltage. It may include a control unit that determines the output voltage based on the voltage.

The monitoring unit measures the forward voltage of at least two light emitting devices, and the control unit may identify a representative value based on the measured forward voltages and determine an output voltage based on the representative value and the driving current. there is.

The control unit may identify one of the average value or the maximum value of the measured forward voltages as a representative value.

The control unit may further include a memory that stores a lookup table of a reference forward voltage according to the driving current, and may determine an output voltage based on the forward voltage and a reference forward voltage corresponding to the driving current.

The control unit may assign a weight to the forward voltage and determine an output voltage based on the weighted forward voltage and the reference forward voltage.

The weight may be assigned based on at least one of the operating time of the display device, ambient temperature, ambient light amount, and the driving current.

The control unit may determine the sum of the reference forward voltage and the weighted forward voltage as the output voltage.

The control unit identifies an overhead voltage based on the forward voltage and a voltage required to operate the driving circuit, and identifies the overhead voltage based on a reference forward voltage corresponding to the overhead voltage and the driving current. The output voltage can be determined.

The monitoring unit measures the forward voltage after a predetermined time, and the control unit can correct the overhead voltage based on the identified overhead voltage and the forward voltage measured after the predetermined time. .

In a method of controlling a display device including a light-emitting unit including a driving circuit for controlling a driving current according to an embodiment, the forward voltage of at least one light-emitting device included in the light-emitting unit is measured, and the driving current is measured. Based on the current and the forward voltage, the output voltage can be determined.

Measuring the forward voltage measures the forward voltage of at least two light emitting devices, and determining the output voltage involves identifying a representative value based on the measured forward voltages, and determining the representative value and the driving current. Based on this, the output voltage can be determined.

To identify the representative value, one of the average value or the maximum value of the measured forward voltages may be identified as the representative value.

It may further include storing a lookup table of a reference forward voltage according to the driving current, and determining the output voltage may determine the output voltage based on the forward voltage and a reference forward voltage corresponding to the driving current. .

Determining the output voltage may include assigning a weight to the forward voltage and determining the output voltage based on the weighted forward voltage and the reference forward voltage.

The weight may be given based on at least one of the operating time of the display device, ambient temperature, and amount of ambient light.

To determine the output voltage, the sum of the reference forward voltage and the weighted forward voltage may be determined as the output voltage.

Determining the output voltage identifies an overhead voltage based on the forward voltage and a voltage required to operate the driving circuit, and determines the reference forward voltage corresponding to the overhead voltage and the driving current. The output voltage can be determined based on .

Measuring the forward voltage further measures the forward voltage after a predetermined time, and determining the output voltage includes an overhead voltage (overhead voltage) based on the identified overhead voltage and the forward voltage measured after the predetermined time. Overhead Voltage) can be corrected.

In a display device including a light-emitting unit including a driving circuit for controlling a driving current according to an embodiment, the display device includes a plurality of light-emitting units and measures the forward voltage of at least one light-emitting unit among the plurality of light-emitting units. It may include a monitoring unit that determines an output voltage based on the driving current and the forward voltage.

One aspect of the present disclosure can prevent an increase in system complexity and cost, and provide a display device and a control method thereof that can determine an appropriate output voltage.

1 is an external view of a display device according to an embodiment of the present invention.

Figure 2 is an exploded view of a display device according to an embodiment of the present invention.

Figure 3 is an exploded view of a back light unit according to an embodiment of the present invention.

Figure 4 is a control block diagram of a display device according to an embodiment of the present invention.

Figure 5 is a diagram illustrating in more detail a control block diagram for a backlight unit according to an embodiment of the present invention.

6 and 7 are diagrams for explaining a monitoring unit according to an embodiment of the present invention.

Figure 8 is a diagram for explaining a lookup table according to an embodiment of the present invention.

Figure 9 is a flowchart for explaining a method of controlling a display device according to an embodiment of the present invention.

Like reference numerals refer to like elements throughout the specification. This specification does not describe all elements of the embodiments, and general content or overlapping content between the embodiments in the technical field to which the disclosed invention pertains is omitted. The term 'unit, module, member, block' used in the specification may be implemented as software or hardware, and depending on the embodiment, a plurality of 'unit, module, member, block' may be implemented as a single component, or It is also possible for one 'part, module, member, or block' to include multiple components.

Throughout the specification, when a part is said to be “connected” to another part, this includes not only direct connection but also indirect connection, and indirect connection includes connection through a wireless communication network. do.

Additionally, when a part "includes" a certain component, this means that it may further include other components rather than excluding other components, unless specifically stated to the contrary.

Throughout the specification, when a member is said to be located “on” another member, this includes not only cases where a member is in contact with another member, but also cases where another member exists between the two members.

Terms such as first and second are used to distinguish one component from another component, and the components are not limited by the above-mentioned terms.

Singular expressions include plural expressions unless the context clearly makes an exception.

The identification code for each step is used for convenience of explanation. The identification code does not explain the order of each step, and each step may be performed differently from the specified order unless a specific order is clearly stated in the context. there is.

Figure 1 is an external view of a display device according to an embodiment of the present invention, Figure 2 is an exploded view of a display device according to an embodiment of the present invention, and Figure 3 is a back light unit (backlight unit) according to an embodiment of the present invention. This is an exploded view of the back light unit.

Referring to FIG. 1, a display device 1 according to an embodiment is a device that processes image data received from the outside and visually displays the image.

As shown in FIG. 1, the display device 1 may be implemented as a TV, but the embodiment of the display device 1 is not limited thereto. For example, the display device 1 may implement a computer monitor, or be included in a navigation terminal device or various portable terminal devices. Here, portable terminal devices may include laptop computers, smart phones, tablet PCs, and personal digital assistants (PDAs).

The display device 1 includes a main body 10 that forms the exterior and accommodates or supports various components constituting the display device 1, and a liquid crystal panel 161 that displays an image.

The main body 10 may be provided with an input button 111 for receiving user commands regarding power on/off, volume control, channel control, screen mode switching, etc. of the display device 1. In addition, a remote controller is provided separately from the input button 111 provided on the main body 10, so that it is possible to receive user commands related to control of the display device 1.

Additionally, various components for displaying images on the liquid crystal panel 161 may be provided inside the main body 10.

For example, as shown in FIG. 2, the main body 10 includes a back light unit 200 that emits surface light forward, and blocks or passes the light emitted from the back light unit 200. A liquid crystal panel 161 that supplies power to the liquid crystal panel 161 and the back light unit 200, a power assembly 145 that supplies power to the liquid crystal panel 161 and the back light unit 200, and a control that controls the operation of the liquid crystal panel 161 and the back light unit 200. Includes assembly 155.

Additionally, the main body 10 includes a bezel 102, a frame middle mold 103, a bottom chassis 104, and a rear cover 105. The bezel 102, frame middle mold 103, bottom chassis 104, and rear cover 105 include power assembly 145, control assembly 155, liquid crystal panel 161, and back light unit 200. Support and secure.

In general, the liquid crystal panel 161 displays image data by applying a gray level voltage to a liquid crystal layer provided with a liquid crystal material with an anisotropic dielectric constant injected between two substrates to adjust the amount of light transmitted through the substrate.

Meanwhile, the liquid crystal panel 161 may be composed of pixels. Here, a pixel is the minimum unit that constitutes the screen displayed through the liquid crystal panel 161, and is also called a dot or pixel, but hereinafter, for convenience of explanation, it will be collectively referred to as a pixel.

Each pixel may receive an electrical signal representing image data and output an optical signal corresponding to the received electrical signal. In this way, optical signals output from a plurality of pixels included in the liquid crystal panel 161 are combined to display image data on the liquid crystal panel 161.

At this time, a pixel electrode is provided in each pixel and is connected to the gate line and source line. The gate line and source line may be configured by methods known to those skilled in the art, and detailed description thereof will be omitted.

Additionally, since the liquid crystal panel 161 cannot emit light on its own, as described above, the display device 1 may be provided with a back light unit 200 that projects back light to the liquid crystal panel 161.

Accordingly, the display device 1 can display desired image data by adjusting the intensity of the gray scale voltage applied to the liquid crystal layer of the liquid crystal panel 161 and adjusting the transmittance of the backlight passing through the liquid crystal layer.

The back light unit 200 may be implemented as a direct type or an edge type, and may also be implemented in various forms known to those skilled in the art. Hereinafter, an example in which the back light unit 200 is provided as a direct type will be described. However, the embodiment of the present invention is not limited to the above example, and the back light unit 200 may be implemented in various known forms.

As shown in FIG. 3, the back light unit 200 includes a light emitting element array 230 that generates light, a reflective sheet 201 that reflects light, a diffuser plate 202 that disperses light, It may include an optical sheet 203 that improves light brightness.

The backlight unit 200 according to one embodiment may be driven in either a low gray level mode or a high gray level mode. The back light unit 200 can be switched from a low-gray-scale mode to a high-gray-scale mode and from a high-gray-scale mode to a low-gray-scale mode according to the control of the control unit 150. The backlight unit 200 may be driven by a driving current with a reduced output range in a low gray level mode or a high gray level mode.

The light emitting element array 230 is provided at the rearmost part of the back light unit 200 and may include a plurality of sub blocks 232. The sub-block 232 may include at least one light-emitting device that generates light, and may include a separate driving circuit for each sub-block 232. The plurality of sub blocks 232 may be arranged parallel to each other to face the liquid crystal panel 161 and may emit light toward the front.

Additionally, the light emitting device array 230 may include a supporter 231 that supports and fixes the plurality of sub blocks 232.

The plurality of sub blocks 232 may be mounted in a predetermined arrangement to have uniform luminance. For example, the plurality of sub blocks 232 may be mounted on the support 231 at equal intervals. The form in which the plurality of sub blocks 232 are arranged on the support 231 may vary.

At this time, the support 231 may supply power to the plurality of sub blocks 232. That is, current may be applied and power may be supplied to the light emitting device included in each of the plurality of sub blocks 232 through the supporter 231. The support 412 may be made of synthetic resin or a printed circuit board (PCB) including a conductive power supply line for supplying power to the plurality of sub-blocks 232 .

The light emitting device included in each of the plurality of sub blocks 232 is a light emitting diode (LED), an organic light emitting diode (OLED), or a quantum dot that can self-emit light based on a supplied current. It may be any one of organic light emitting devices (quantum dot-organic light emitting diode, QD-OLED). However, the type of light-emitting device is not limited to this, and any device that emits light according to current may be included without limitation.

The reflective sheet 201 is provided in front of the light emitting element array 230 and can reflect light traveling behind the back light unit 200 forward.

A through hole 201a is formed in the reflective sheet 201 at a position corresponding to the sub block 232. Additionally, the light emitting device of the sub block 232 may pass through the through hole 201a and protrude in front of the reflective sheet 201. Since the light emitting device of the sub block 232 emits light in various directions in front of the reflective sheet 201, some of the light emitted from the light emitting device may travel backward. The reflective film included in the reflective sheet 201 can reflect light emitted backward from the light emitting device forward.

The diffusion plate 204 may be provided in front of the light-emitting device array 230 and the reflective sheet 201 and can evenly disperse light emitted from the light-emitting devices of the light-emitting device array 230.

Light-emitting elements are located in various places on the back of the back light unit 200. Even if a plurality of light-emitting devices are disposed at equal intervals on the rear of the backlight unit 200, non-uniformity in luminance may occur depending on the positions of the light-emitting devices. The diffusion plate 204 can diffuse the light emitted from the light-emitting device within the diffusion plate 204 to eliminate uneven luminance caused by the light-emitting device. In this way, the diffusion plate 204 can uniformly emit light incident from the light emitting device array 230 to the entire surface.

This diffusion plate 204 may be made of poly methyl methacrylate (PMMA) or polycarbonate (PC) to which a diffusion agent for light diffusion is added.

The optical sheet 203 may include various sheets to improve luminance and uniformity of luminance. For example, the optical sheet 203 may include a diffusion sheet, a first prism sheet, a second prism sheet, and a reflective polarizing sheet.

In addition, depending on the embodiment, the back light unit 200 may further include a quantum dot film (not shown) that can change the color of light emitted from the light emitting device. In this case, the quantum dot film may be provided between the diffusion plate 202 and the optical sheet 203. In addition, the back light unit 200 may include various sheets, depending on the embodiment.

Meanwhile, according to the disclosure, the light-emitting element of the display device 1 is described as the back light unit 200, but the display device 1 includes a plurality of LEDs that emit light on a transparent substrate (not shown) in addition to the back light unit 200. (Light Emitting Diode, not shown). The light emitting unit (not shown) of the display device 1 may be either the back light unit 200 or a plurality of LEDs. The plurality of LEDs may include single-color LED elements, or may be polychromatic, including multi-color LED elements, such as yellow LED elements, green LED elements, and/or blue LED elements. At this time, each of the plurality of LEDs may be connected to an electrode by a signal line, and may include a driving current that controls the driving current based on image data.

In the above, the physical structure of the display device 1 has been described in detail. Below, each component of the display device 1 will be described in detail, and controlling the backlight unit 200 to support either low brightness or high brightness will be briefly explained.

FIG. 4 is a control block diagram of the display device 1 according to an embodiment of the present invention, and FIG. 5 is a more detailed control block diagram of the back light unit 200 according to an embodiment of the present invention. It is a drawing.

Referring to FIG. 4, the display device 1 according to one embodiment includes an input unit 110 that receives various control commands from a user, and a content receiver 120 that receives content including images and sounds from an external device. and a communication unit 130 that transmits and receives various data such as content through a communication network, a power supply unit 140 that supplies power to each component of the display device 1, and processes content received from the outside and A control unit 150 that controls each component to output corresponding images and sounds, a display unit 160 including a liquid crystal panel 161 that displays images corresponding to the content, and an audio device that outputs sounds corresponding to the contents. It includes an output unit 170 and a back light unit 200 that supplies backlight. However, depending on the embodiment, the display device 1 may omit some of the configurations described above.

The input unit 110 can receive various control commands from the user.

For example, the input unit 110 may include an input button 111, as shown in FIG. 4 . The input button 111 according to one embodiment includes a power button for turning on/off the power of the display device 1, a channel button for changing the channel received by the content receiver 120, and a sound output unit 170. It may include a volume button to adjust the volume of the output sound.

Meanwhile, various buttons included in the input button 111 include a push switch and a membrane switch that detect the user's pressure, or a touch switch that detects contact with a part of the user's body. can be hired. However, it is not limited to this, and the input button 111 may employ various input means that can output an electrical signal to the control unit 150 in response to a specific user's action.

Additionally, the input unit 110 according to one embodiment may include a signal receiver 112 that receives a remote control signal from a remote controller.

At this time, the remote controller that obtains the user input may be provided separately from the display device 1, obtains the user input, and transmits a wireless signal corresponding to the user input to the display device 1.

The signal receiver 112 may receive a wireless signal from the remote controller and output an electrical signal corresponding to the user input to the control unit 150.

In addition, the input unit 110 may include various known components that can receive control commands from the user, but there is no limitation. Additionally, when the liquid crystal panel 161 is implemented as a touch screen type, the liquid crystal panel 161 may perform the function of the input unit 110.

The content receiving unit 120 may include a receiving terminal 121 and a tuner 122 that receive content including video data and/or sound signals from content sources.

The image data includes luminance data, so that the luminance required by the plurality of sub-blocks 232 is transmitted to the control unit 150 to determine whether the image data is low gray level or high gray level. Specifically, the control unit 150 may determine whether the image data is low gray level or high gray level based on the maximum brightness that can be produced in a specific mode, and determine the output range of the driving circuit 234 (FIG. 5).

The receiving terminal 121 is a coaxial cable connector (RF coaxial cable connector) that receives a broadcast signal containing content from an antenna, a high definition multimedia interface (HDMI) that receives content from a set-top box or a multimedia playback device. ) connector, component video connector, composite video connector, D-sub connector, etc.

The tuner 122 may receive a broadcast signal from a broadcast reception antenna or a wired cable, and extract a broadcast signal of a channel selected by the user from among the broadcast signals. For example, the tuner 122 may pass a broadcast signal having a frequency corresponding to a channel selected by the user among a plurality of broadcast signals received through a broadcast reception antenna or a wired cable and block broadcast signals having a different frequency. there is.

In this way, the content receiver 120 can receive video data and sound signals from content sources through the reception terminal 121 and/or the tuner 122, and sends the video data and/or sound signals to the control unit 150. ) can be output.

The communication unit 130 can receive various contents through wireless or wired communication. To this end, the communication unit 130 may include a wireless communication module supporting a wireless communication method and a wired communication module supporting a wired communication method.

Wireless communications include, for example, ^5th generation (5G), LTE, LTE Advance (LTE-A), code division multiple access (CDMA), wideband CDMA (WCDMA), universal mobile telecommunications system (UMTS), and Wibro (wireless). It may include cellular communication using at least one of broadband), or GSM (global system for mobile communications). According to one embodiment, wireless communication is, for example, wireless fidelity (WiFi), Bluetooth, Bluetooth low energy (BLE), zigbee, near field communication (NFC), magnetic secure transmission, radio. It may include at least one of frequency (RF) or body area network (BAN). According to one embodiment, wireless communications may include GNSS.

Additionally, wired communication methods include, but are not limited to, PCI (peripheral component interconnect), PCI-express, and USB (universe serial bus).

The power supply unit 140 may supply power to each component of the display device 1.

For example, the power supply unit 140 may supply power to the display unit 160. Specifically, the power supply unit 140 can supply the driving voltage of each of the source driver (not shown) and the gate driver (not shown) of the display unit 160, and the common voltage required for the liquid crystal layer of the liquid crystal panel 161 ( Vcom) can be supplied through each pixel electrode.

Additionally, the power supply unit 140 may supply power to the back light unit 200. Specifically, the power supply unit 140 may supply driving voltages to each of the source driver 210 and the gate driver 220 of the back light unit 200, and may also transmit the voltage to the light emitting device array 230. Power supply to the back light unit 200 will be described in detail later.

To this end, the power supply unit 140 may include a DC/DC converter PAM driver and a PWM driver, and depending on the embodiment, may be provided in the form of a separate integrated circuit (IC), and a power assembly ( 145) can be responded to.

The control unit 150 according to one embodiment may include at least one memory 152 that stores a program that performs the above-described operation and the operation that will be described later, and at least one processor 151 that executes the stored program. , may correspond to the control assembly 155.

The processor 151 according to one embodiment may process content received through the content receiver 120 or the communication unit 130 to obtain image data corresponding to the content.

Additionally, the processor 151 according to one embodiment controls the display unit 160 and the back light unit 200 based on image data to display a corresponding image.

The processor 151 according to an embodiment may determine the luminance corresponding to each of the plurality of sub-blocks 232 included in the back light unit 200 based on image data. That is, the processor 151 can determine the luminance required for each sub-block 232 based on the image data. The processor 151 may determine the minimum or maximum value of the output range of the driving current output from the driving circuit 234 based on the luminance data for the frame. Once the output range is determined, the driving circuit 234 can provide the necessary driving current to a plurality of positions for each frame.

The processor 151 may determine a grayscale corresponding to each pixel of the liquid crystal panel 161 based on the image data, and may determine a grayscale corresponding to each pixel of the liquid crystal panel 161 based on the determined grayscale. The luminance can be determined.

In other words, the sub-block 232 of the backlight unit 200, which irradiates light to pixels requiring low gradation, is determined to require low luminance, and the backlight irradiates light to pixels requiring high gradation. The sub-block 232 of the unit 200 may be determined to require high luminance.

The luminance determination for each of the plurality of sub-blocks 232 of the backlight unit 200 may be performed on a frame-by-frame basis.

The processor 151 may determine a driving current (source voltage) corresponding to each sub-block 232 so that each sub-block 232 can emit light with the required luminance.

Additionally, the processor 151 may determine the output voltage based on the driving current (source voltage) corresponding to the sub-block 232 and the forward voltage of the light emitting device measured by the monitoring unit 240. That is, the processor 151 may determine the final voltage that the source driver 210 outputs to the sub-block 232 based on the driving current (source voltage) and forward voltage (forward voltage) corresponding to the image data.

The memory 152 may store information about the correlation between luminance and driving current.

Additionally, the memory 152 may store information about the correlation between grayscale and luminance. For example, if the number of gray levels for the display device 1 to express luminance is 1024, the memory 152 can distinguish and store the corresponding luminance levels. Accordingly, the processor 151 can control the sub-block 232 to emit light with a luminance corresponding to the gray level.

Additionally, the memory 152 may store a look-up table of the reference forward voltage according to the driving current corresponding to the image data, as will be described in detail below. This may be data measured in the production process and stored in advance, but is not limited to this. For example, the lookup table may be stored according to update information received from the communication unit 130 based on control of the control unit 150.

As such, the memory 152 includes cache, read only memory (ROM), programmable ROM (PROM), erasable programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), and flash memory (flash) to store various information. It may be implemented with at least one of a non-volatile memory device such as a memory) or a volatile memory device such as a random access memory (RAM). However, it is not limited to this, and any type that can store various types of information can be used as the type of memory 152.

The display unit 160 according to one embodiment may display an image by receiving image data from the control unit 150 and driving the liquid crystal panel 161 based on the input image data.

To this end, the display unit 160 includes a source driver (not shown), a gate driver (not shown), and a timing control unit (not shown) that transmits the gate control signal and the source control signal to control the overall operation of the source driver and the gate driver. includes poetry).

In addition, the display unit 160 includes a plurality of gate lines that transmit gate signals, a plurality of source lines that intersect the gate lines, and a plurality of source lines that transmit gray-level voltages, and is formed in an area surrounded by the gate lines and source lines. It includes a liquid crystal panel 161 including a plurality of pixel electrodes in a matrix form connected through a switching element that acts as a switch between the gate line and the source line.

Depending on the embodiment, the switching element may be a thin film transistor (TFT), and may be implemented with various elements known to those skilled in the art.

At this time, each of the pixels rotates the liquid crystal of the liquid crystal layer by the electric field between the pixel electrode to which the gray level voltage is applied and the common electrode to which the common voltage (Vcom) is applied through the thin film transistor, thereby adjusting the amount of light transmission to display image data. It can be displayed.

The sound output unit 170 may receive sound data of content received through the content receiver 120 or the communication unit 130 under the control of the processor 151 and output sound. At this time, the audio output unit 170 may include one or more speakers 171 that convert electrical signals into acoustic signals.

The backlight unit 200 includes a light-emitting device array 230 that irradiates light to the liquid crystal panel 161, a source driver 210 that supplies a source voltage to the light-emitting device array 230, and a light-emitting device array 230. ) and/or a gate driver 220 that supplies a gate signal to the light emitting device array 230 and/or a monitoring unit 240 that measures the forward voltage of the light emitting device.

Additionally, the back light unit 200 may include a timing controller (not shown) that controls the timing of the source driver 210 and the gate driver 220, depending on the embodiment. may be provided as a single IC with the control unit 150, or may be provided as a separate IC. Hereinafter, it will be explained that the control unit 150 also performs the function of the timing control unit.

As shown in FIG. 5, the back light unit 200 has a plurality of gate lines (GL ₁ , GL ₂ , GL ₃ ) that transmit gate signals.

GL _m ), gate lines (GL ₁ , GL ₂ , GL ₃

A plurality of source lines (DL ₁ , DL ₂ , DL ₃ ) are formed to cross GL _m ) and transmit source voltages.

DL _n ), and gate lines (GL ₁ , GL ₂ , GL ₃

GL _m ) and source lines (DL ₁ , DL ₂ , DL ₃

It is formed in the area surrounded by DL _n ) and has gate lines (GL ₁ , GL ₂ , GL ₃

GL _m ) and source lines (DL ₁ , DL ₂ , DL ₃

DL _n ) a plurality of sub-blocks 232 in the form of a matrix connected through a switching element that acts as a switch between them, and a monitoring unit 240 that measures the forward voltage of at least one light-emitting element included in the sub-block 232. It includes a light emitting device array 230 that includes.

That is, the light emitting device array 230 may include a plurality of sub-blocks 232 each connected to one gate line and one source line, and each of the plurality of sub-blocks 232 includes a gate signal and a source line. It may include a driving circuit 234 that supplies driving current to the light emitting device based on voltage and a monitoring unit 240 that measures the forward voltage of the light emitting device.

The source driver 210 according to one embodiment sets the output timing of the source voltage, the size, and polarity of the source voltage according to the source control signal and image data input from the control unit 150, and sets the source voltage according to the supply timing. An appropriate source voltage can be output through the lines (DL ₁ , DL ₂ , DL _{3 x} DL _n ).

That is, the source driver 210 can supply the source voltage corresponding to the luminance required by each sub-block 232 to the corresponding sub-block 232 through the corresponding source line, under the control of the controller 150. , the source voltage corresponding to the output voltage determined based on the forward voltage of the light emitting device can be supplied to the corresponding subblock 223 through the corresponding source line.

In other words, the source driver 210 converts the luminance data corresponding to the image data received from the control unit 150 into an analog source voltage based on the driving voltage supplied from the power supply unit 140 to create a light emitting element array ( 230) source lines (DL ₁ , DL ₂ , DL ₃ ) arranged on

DL _n ) can be applied to each, and the source driver 210 applies a source voltage corresponding to the output voltage determined by the control unit 150 on the light emitting element array 230, based on the voltage supplied from the power supply unit 140. It can be applied to each of the source lines (DL ₁ , DL ₂ , DL ₃ , and DL _n ) arranged in .

The source driver 210 may include at least one source driver IC, and the number of source driver ICs may be determined according to specifications such as the size and resolution of the light emitting device array 230.

The gate driver 220 operates gate lines (GL ₁ , GL ₂ , GL ₃₎ .

It may be connected to one or both ends of GL _m ), and generates a plurality of gate signals using the gate control signal provided from the control unit 150 and the gate on/off voltages supplied from the voltage supply unit 140, and the gate Signals are transmitted through gate lines (GL ₁ , GL ₂ , GL ₃ ) arranged on the light emitting device array 230.

GL _m ) can be applied.

The gate driver 220 may include at least one gate drive IC, and the gate drive IC may be determined according to specifications such as the size and resolution of the light emitting device array 230.

That is, the gate driver IC of the gate driver 220 can receive a gate control signal and sequentially apply an on/off voltage, that is, an on/off signal, through the gate line. Accordingly, the gate driver IC can sequentially turn on/off the switching elements connected to the gate line.

Accordingly, the luminance data to be displayed in the sub-block 232 connected to the gate line is converted into a source voltage divided into a plurality of voltages and applied to each source line. At this time, a gate signal is sequentially applied to all gate lines during one frame period, and a source voltage corresponding to luminance data is applied to all sub-block 232 rows, so that the light emitting device array 230 corresponds to one frame. The backlight can be provided by the liquid crystal panel 161.

The light emitting device array 230 may include a plurality of light emitting devices arranged in a matrix form.

The light-emitting device array 230 may include a plurality of sub-blocks 232, each of which includes and controls at least one light-emitting device.

At this time, each sub-block 232 may include a driving circuit 234, and the driving circuit 234 is connected to one gate line and one source line to provide a gate signal, source voltage, and peak voltage. By receiving the , connected light emitting elements can be controlled.

One sub-block 232 includes a driving circuit 234, at least one light-emitting element 236, and a monitoring unit 240.

The monitoring unit 240 may understand that, in order to measure the voltage drop of at least one light emitting device, conventionally known voltage drop measurement technology may be applied, and voltage drop measurement technology to be developed in the future may be applied.

More specifically, the monitoring unit 240 may measure the forward voltage of the sub-block 232 and/or at least one light-emitting device included in the sub-block 232. As an example, a plurality of monitoring units 240 may be provided in each of the plurality of sub-blocks 232, and may be provided in at least one sub-block 232 among the plurality of sub-blocks 232 to monitor at least one sub-block ( 232) can measure the forward voltage. That is, the monitoring unit 240 is not limited to being provided for each sub-block 232 as shown in FIG. 5, but is provided in at least one arbitrary sub-block 232 among the plurality of sub-blocks 232. , the forward voltage of the light emitting device included in the sub block 232 can be measured.

Additionally, the monitoring unit 240 may measure the forward voltage of at least one light emitting device and transmit the measured forward voltage value to the control unit 150 .

The first switching element (not shown) included in the driving circuit 234 switches the light emitting element (not shown) based on the source voltage corresponding to the required brightness so that the light emitting element (not shown) can irradiate light with the required brightness. The amount of current transmitted can be adjusted.

The switching element can receive an amount of charge corresponding to the source voltage from the capacitor C through the gate terminal.

The second switching element (not shown) can receive a gate signal through a gate line, and when receiving the gate signal, the source voltage can be supplied to the drain terminal to charge the capacitor (C).

Depending on the embodiment, the first switching element and the second switching element may be a thin film transistor (TFT), and may be implemented with various elements known to those skilled in the art.

As described above, the controller 150 may determine the luminance required by each of the plurality of sub-blocks 232 based on the image data, and set the source voltage required for each sub-block 232 based on the determined luminance. Based on the reference forward voltage according to the driving current required for each sub-block 232 based on the determined or determined luminance and the forward voltage of at least one arbitrary light emitting element measured by the monitoring unit 240 The output voltage can be determined. Thereafter, the control unit 150 may control the source driver 210 and the gate driver 220 to supply the source voltage corresponding to each sub-block 232. At this time, the control unit 150 can control the power supply unit 140 to supply necessary power to the source driver 210, the gate driver 220, the light emitting device array 230, and the monitoring unit 240.

In the above, each configuration of the display device 1 has been described. Hereinafter, an embodiment of determining the output voltage of the display device 1 applied to the disclosed invention will be described in detail.

The display device 1 according to an embodiment can prevent an increase in system complexity and cost and determine an appropriate output voltage. To this end, the display device 1 includes a light emitting unit including a driving circuit that controls the driving current, and a monitoring unit that measures the forward voltage of at least one light emitting element among the light emitting elements included in the light emitting unit ( 240) and a control unit 150 that determines the output voltage based on the driving current and forward voltage.

Here, the driving current may mean, for example, a driving current corresponding to the control unit 150 so that each sub-block 232 can irradiate light with a required luminance based on image data.

The display device 1 may measure the forward voltage measured from the monitoring unit 240 to determine the final output voltage to the driving circuit 234. The forward voltage measured here can be measured by the monitoring unit 240 even when the display device 1 is running.

The forward voltage of a light-emitting device decreases as the surrounding temperature increases, and tends to increase as the surrounding temperature decreases. The forward voltage varies depending on the type of light-emitting device (Red, Green, Blue, etc.). There is a characteristic that has. In order to reflect these characteristics, the monitoring unit 240 may measure the forward voltage reflecting the ambient temperature and heat generated when the display device 1 is driven.

More specifically, the monitoring unit 240 of the display device 1 is connected in parallel with at least one light-emitting element to measure the voltage drop of the at least one light-emitting element included in the light-emitting unit, and is connected in parallel to the forward voltage (Forward Voltage) can be measured.

In another embodiment, the monitoring unit 240 measures the magnitude of the voltage dropped in the sub-block 232 including at least one light-emitting device, and determines the number and connection method of the light-emitting devices included in the sub-block 232. The average forward voltage of one light emitting device can be measured based on (series and/or parallel).

Referring to FIG. 6 , the light emitting device array 230 may include a driving circuit 234, at least one light emitting device 236 connected in series, and a monitoring unit 240. As shown in FIG. 6, when the light-emitting device 236 is connected in series, the monitoring unit 240 is connected in parallel with the light-emitting device 236 to measure the forward voltage of the light-emitting device 236. You can.

Illustratively, the monitoring unit 240 is connected in parallel with at least one light-emitting device 236, measures the voltage dropped by the plurality of light-emitting devices 236, and determines the number of light-emitting devices 236 and the voltage drop. Based on the voltage, the average forward voltage of the light emitting device 236 can be determined.

Referring to FIG. 7 , the light emitting device array 230 may include a driving circuit 234, at least one light emitting device 236 connected in parallel, and a monitoring unit 240. As shown in FIG. 7 , when the light emitting devices 236 are connected in parallel, the monitoring unit 240 is connected in parallel with one light emitting device 236 and can measure the forward voltage.

More specifically, the monitoring unit 240 has a first input terminal (+) connected to the anode electrode of any light-emitting element 236 among the plurality of light-emitting elements 236, and a second input terminal (+) connected to the cathode electrode of the light-emitting element 236. The forward voltage of one light emitting device can be measured by measuring the voltage difference (drop) at the input terminal (-).

Meanwhile, the monitoring unit 240 is illustratively provided for each of the plurality of sub-blocks 232 and can measure the average forward voltage of the light-emitting devices included in each sub-block 232. That is, in the case where there are 16 sub-blocks 232, 16 monitoring units 240 may be provided for each sub-block 232. However, it is not limited to this.

In another embodiment, at least one monitoring unit 240 may be provided to measure the average forward voltage of at least one random sub-block 232 among the plurality of sub-blocks 232. Accordingly, even without measuring the forward voltage of all light-emitting devices 236, the average forward voltage of some light-emitting devices 236 whose characteristics change according to ambient temperature and heat generation according to the operating time of the display device 1 (Forward Voltage) can be measured.

The control unit 150 of the display device 1 according to one embodiment represents the at least one average forward voltage (Forward Voltage) and/or the at least one forward voltage (Forward Voltage) measured by the monitoring unit 240. The value can be identified.

Illustratively, the control unit 150 of the display device 1 may identify the average value of at least one measured forward voltage and/or the average value of at least one measured average forward voltage as a representative value. You can. In another embodiment, the control unit 150 may identify the maximum value of at least one measured forward voltage (Forward Voltage) and/or at least one measured average forward voltage (Forward Voltage) as a representative value. Meanwhile, the representative value is not limited to this. In other words, a method of identifying a representative value can be identified by 6-sigma.

More specifically, in the case where the monitoring unit 240 is provided in the first and second sub-blocks (not shown) to measure the average forward voltage, the first sub-block (not shown) of the display device 1 ) is 3V and the average forward voltage of the second sub-block (not shown) is 2.8V, the control unit of the display device 1 sets the representative value to 2.9 V (average) or 3 V (maximum value). can be identified.

That is, the control unit 150 may identify one of the average value or the maximum value of at least one measured forward voltage as a representative value. Accordingly, the display device 1 can obtain a forward voltage value that reflects the characteristics according to the operating time and ambient temperature of the display device 1 even if the forward voltage of all light-emitting elements is not measured.

Meanwhile, the display device 1 may include a memory capable of storing a look-up table regarding the reference forward voltage corresponding to the driving current. Here, the look-up table may be measured in advance during the production process of the display device 1. However, it is not limited to this.

Referring to FIG. 8 , the look-up table may be a graph and/or a corresponding value for a reference forward voltage corresponding to a driving current determined based on image data depending on the type of light-emitting device. As shown in FIG. 8, the lookup table determines the reference temperature (e.g., 25

) may include reference forward voltage values corresponding to the driving current determined based on image data of the light emitting device. However, it is not limited to this.

Exemplarily, when the driving current of the red light-emitting element determined based on image data is 50 mA, the control unit 150 of the display device 1 may generate a current corresponding to 50 mA based on a pre-stored lookup table. The forward voltage of 2.38V can be identified (R1) as the reference forward voltage. However, it is not limited as shown. That is, Figure 8 is an example and may further include a look-up table regarding the reference forward voltage corresponding to the driving current for the yellow light-emitting device, and when the case of a multi-color light-emitting device is included, the driving of the corresponding multi-color light-emitting device A lookup table regarding the reference forward voltage corresponding to the current may be further included.

Additionally, the lookup table may include a detailed lookup table according to the reference temperature. That is, the look-up table is for each representative temperature within the drivable temperature range of the display device 1 (for example, 20

, 25

, 30

etc.) may include a lookup table including a reference forward voltage according to the reference voltage. Accordingly, when information about the ambient temperature is received from an external device (e.g., an air conditioner, etc.) through the communication unit 130 of the display device 1, the control unit 150 of the display device 1 determines the ambient temperature. By applying the corresponding lookup table, the reference forward voltage can be identified.

Accordingly, the control unit 150 of the display device 1 may identify the reference forward voltage corresponding to the driving current and determine the output voltage based on the identified reference forward voltage and the measured forward voltage.

The control unit 150 of the display device 1 according to one embodiment may assign weight to the measured forward voltage. Here, the weight may be a predetermined weight and may be a value given based on at least one of the operating time of the display device 1, ambient temperature, ambient light amount, and driving current. As an example, the control unit 150 of the display device 1 may assign a weight to the measured forward voltage based on the size of the driving current corresponding to the sub-block 232. That is, the controller 150 may assign a smaller weight as the magnitude of the driving current corresponding to the sub-block 232 increases.

Accordingly, the control unit 150 of the display device 1 identifies the reference forward voltage corresponding to the driving current corresponding to the required luminance based on the lookup table, and calculates the identified reference forward voltage and the weighted measured forward voltage. The output voltage can be determined based on the voltage.

Meanwhile, the predetermined weight is a value determined experimentally and empirically, and may be a value set to minimize power consumption of the display device 1 and prevent heat generation and decrease in brightness. However, it is not limited to this. Therefore, it can be understood that the parameters that determine the weight can be applied in more diverse ways.

The output voltage of the display device 1 according to one embodiment may be determined based on Equation 1 below.

[Equation 1]

Here, Vled is the output voltage of the display device 1, LED Vf is the reference forward voltage of the lookup table corresponding to the driving current,

may mean a weight.

More specifically, referring to Equation 1, the control unit 150 of the display device 1 controls the forward voltage measured by the above-described monitoring unit 240 and the driving circuit 234 of the sub-block 232. The overhead voltage can be calculated by adding up the power required for operation. However, it is not limited to this. In another embodiment, the overhead voltage may be a measured forward voltage, and accordingly, the weight may be determined based on the power required for operation of the driving circuit 234.

Accordingly, the control unit 150 of the display device 1 generates an output voltage by adding the reference forward voltage and the weighted overhead voltage corresponding to the driving current determined by the luminance required according to the image data. You can decide.

The control unit 150 of the display device 1 according to an embodiment of the present invention may correct the overhead voltage and determine the output voltage based on the corrected overhead voltage.

More specifically, when the overhead voltage (Overhead Voltage) is determined, the control unit 150 may measure the forward voltage (Forward Voltage) of the light emitting device according to a predetermined time. In this case, the control unit 150 of the display device 1 may calculate the corrected overhead voltage based on the existing overhead voltage and the newly measured forward voltage. .

More specifically, the control unit 150 multiplies the existing overhead voltage (Overhead Volate) by the weight x, and the forward voltage measured according to a predetermined time is multiplied by the weight y to calculate the overhead voltage Voltage) can be corrected. Here, the weights x and y can be set arbitrarily, and their sum can be determined to be 1. However, it is not limited to this.

For example, in the case where x corresponds to 0.9 and y equals 0.1 and the existing overhead voltage is 3V, the forward voltage measured by the monitoring unit 240 after a predetermined time is When it is 2.7 V, the display device 1 control unit 150 can correct the overhead voltage to 2.97 V. Accordingly, the control unit 150 weights the corrected overhead voltage.

is given, and the output voltage can be determined based on the weighted corrected overhead voltage and the reference forward voltage.

Accordingly, the display device 1 corrects the overhead voltage by varying the ratio between the calculated overhead voltage and the forward voltage measured according to a predetermined time, thereby Power consumption can be minimized by controlling the output voltage by reflecting changes in characteristics according to operating time as well as the surrounding temperature.

Meanwhile, the above-described embodiment is explained using FIG. 7 as an example in which the control unit 150 of the display device 1 has at least one light-emitting element connected in parallel. That is, the output voltage determined by the control unit 150 may mean the output voltage when at least one light-emitting device 236 is connected in parallel, as exemplarily shown in FIG. 7 . Therefore, it can be understood that in the case where at least one light-emitting device 236 is connected in series as shown in FIG. 6, the overhead voltage may increase depending on the number of light-emitting devices 236 connected in series.

Referring to FIG. 9, the display device 1 can measure the forward voltage of at least one light emitting diode among the light emitting elements (light emitting diodes) included in the light emitting unit (S110).

Additionally, the display device 1 can identify a representative value based on the measured forward voltage (S120).

Additionally, the display device 1 may assign weight to the identified representative value (S130).

Additionally, the display device 1 may determine the output voltage based on the reference output voltage corresponding to the driving current of the light emitting unit and the representative value weighted in step S130 (S140).

Meanwhile, the disclosed embodiments may be implemented in the form of a recording medium that stores instructions executable by a computer. Instructions may be stored in the form of program code, and when executed by a processor, may create program modules to perform operations of the disclosed embodiments. The recording medium may be implemented as a computer-readable recording medium.

Computer-readable recording media include all types of recording media storing instructions that can be decoded by a computer. For example, there may be read only memory (ROM), random access memory (RAM), magnetic tape, magnetic disk, flash memory, and optical data storage devices.

As described above, the disclosed embodiments have been described with reference to the attached drawings. A person skilled in the art to which the present invention pertains will understand that the present invention can be practiced in forms different from the disclosed embodiments without changing the technical idea or essential features of the present invention. The disclosed embodiments are illustrative and should not be construed as limiting.

Claims

A light emitting unit including a driving circuit that controls driving current;

a monitoring unit that measures the forward voltage of at least one light-emitting element included in the light-emitting unit; and

A display device comprising: a control unit that determines an output voltage based on the driving current and the forward voltage.
According to paragraph 1,

The monitoring unit is,

Measure the forward voltage of at least two light emitting elements,

The control unit,

Identifying a representative value based on the measured forward voltages,

A display device that determines an output voltage based on the representative value and the driving current.
According to paragraph 2,

The control unit,

A display device that identifies one of the average or maximum values of the measured forward voltages as a representative value.
According to paragraph 1,

The control unit,

It further includes a memory that stores a look-up table of the reference forward voltage according to the driving current,

A display device that determines an output voltage based on the forward voltage and a reference forward voltage corresponding to the driving current.
According to paragraph 4,

The control unit,

A display device that weights the forward voltage and determines an output voltage based on the weighted forward voltage and the reference forward voltage.
According to clause 5,

The weight is,

A display device that is given based on at least one of the operating time of the display device, ambient temperature, ambient light amount, and the driving current.
According to clause 6,

The control unit,

A display device that determines the sum of the reference forward voltage and the weighted forward voltage as the output voltage.
According to paragraph 4,

The control unit,

Identifying an overhead voltage based on the forward voltage and a voltage required to operate the driving circuit,

A display device that determines an output voltage based on the overhead voltage and a reference forward voltage corresponding to the driving current.
According to clause 8,

The monitoring unit is,

Measure the forward voltage after a predetermined time,

The control unit,

A display device that corrects overhead voltage based on the identified overhead voltage and the forward voltage measured after the predetermined time.
In a method of controlling a display device including a light emitting unit including a driving circuit for controlling driving current,

Measure the forward voltage of at least one light-emitting element included in the light-emitting unit,

A display control method for determining an output voltage based on the driving current and the forward voltage.
According to clause 10,

Measuring the forward voltage is,

Measure the forward voltage of at least two light emitting elements,

Determining the output voltage is,

Identifying a representative value based on the measured forward voltages,

A display control method for determining an output voltage based on the representative value and the driving current.
According to clause 11,

Identifying the representative value is,

A display control method that identifies one of the average or maximum values of the measured forward voltages as a representative value.
According to clause 10,

Further comprising storing a lookup table of reference forward voltage according to the driving current,

Determining the output voltage is,

A display control method for determining an output voltage based on the forward voltage and a reference forward voltage corresponding to the driving current.
According to clause 13,

Determining the output voltage is,

A display control method for weighting the forward voltage and determining an output voltage based on the weighted forward voltage and the reference forward voltage.
According to clause 14,

The weight is,

A display control method that is given based on at least one of the operating time of the display device, ambient temperature, and ambient light amount.