Display module and display apparatus having same

Abstract

A display module according to one aspect of the invention disclosed herein may comprise: a substrate; and a plurality of pixel circuits provided on the substrate, wherein each of the plurality of pixel circuits may include a plurality of light-emitting diodes (LEDs) connected in series or in parallel, a driving TFT for applying a driving current to the plurality of LEDs, and a variable power supply unit for adjusting the voltage supplied to the driving TFT in order to compensate for a voltage drop caused by the plurality of LEDs.

Description

Display module and display device including the same

[0001] The disclosed invention relates to a display module that implements an image using an inorganic light-emitting element and a display device including the same.

[0002] In general, a display device is a type of output device that converts acquired or stored electrical information into visual information and displays it to the user, and is used in various fields such as homes and businesses.

[0003] Display devices can be divided into self-luminous displays, in which each pixel emits its own light, and non-luminous displays, which require a separate light source.

[0004] LCD (Liquid Crystal Display) is a typical non-luminous display, and it is structurally complex and has limitations in implementing a thin thickness because it requires a backlight unit that supplies light from the rear of the display panel, a liquid crystal layer that acts as a switch to allow / block light to pass through, and a color filter that changes the supplied light into the desired color.

[0005] On the other hand, self-luminous displays, which feature individual light-emitting elements at each pixel, eliminate the need for components like backlight units and liquid crystal layers, and can even omit color filters. This allows for a simple structure and a high degree of design freedom. Furthermore, they can achieve a thin profile and excellent contrast ratio, brightness, and viewing angle.

[0006] Among self-illuminating displays, micro LED displays consist of multiple micro-sized LEDs. Compared to LCDs, which require backlighting, micro LED displays can offer superior contrast, response time, and energy efficiency.

[0007] Additionally, micro LEDs, which are inorganic light-emitting devices, are brighter, have better luminous efficiency, and have a longer lifespan than OLEDs, which require a separate encapsulation layer to protect the organic material.

[0008] One aspect of the disclosed invention provides a display module and a display device including the same, which can achieve high brightness and high efficiency by arranging a plurality of LEDs in a pixel circuit in series or parallel according to LED characteristics and compensating for voltage drops according to the plurality of LEDs through a variable power supply.

[0009] The technical problems to be achieved in this document are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0010] A display module according to one aspect of the disclosed invention includes a substrate; a plurality of pixel circuits provided on the substrate; and each of the plurality of pixel circuits may include a plurality of LEDs connected in series or in parallel; a driving TFT for applying a driving current to the plurality of LEDs; and a variable power supply for adjusting a voltage supplied to the driving TFT to compensate for a voltage drop caused by the plurality of LEDs.

[0011] A display device according to one aspect of the disclosed invention comprises: a frame; a plurality of display modules arranged in a two-dimensional matrix on the frame; each of the plurality of display modules comprising: a substrate; a plurality of pixel circuits provided on the substrate; and each of the plurality of pixel circuits may comprise: a plurality of LEDs connected in series or in parallel; a driving TFT for applying a driving current to the plurality of LEDs; and a variable power supply for adjusting a voltage supplied to the driving TFT to compensate for a voltage drop caused by the plurality of LEDs.

[0012] FIG. 1 is a perspective view showing an example of a display module and a display device including the same according to one embodiment of the present disclosure.

[0013] FIG. 2 is a drawing showing an example of a pixel array constituting a unit module of a display device according to one embodiment of the present disclosure.

[0014] FIG. 3 is a block diagram of a display device according to one embodiment of the present disclosure.

[0015] FIG. 4 is a block diagram illustrating the configuration of a display module included in a display device according to one embodiment of the present disclosure.

[0016] FIG. 5 is a diagram conceptually illustrating how each pixel is driven in a display module according to one embodiment of the present disclosure.

[0017] FIG. 6 is a circuit diagram schematically illustrating a pixel circuit for controlling pixels in a display module according to one embodiment of the present disclosure.

[0018] FIG. 7 is a drawing showing a connection structure for each LED according to one embodiment of the present disclosure.

[0019] FIG. 8 is a drawing showing a connection structure of a power supply unit according to one embodiment of the present disclosure.

[0020] FIG. 9 is a diagram showing efficiency according to current flowing through an LED according to one embodiment of the present disclosure.

[0021] FIG. 10 is a diagram for explaining voltage drop by multiple LEDs according to one embodiment of the present disclosure.

[0022] It should be understood that the various embodiments and terms used in this document are not intended to limit the technical features described in this document to specific embodiments, but rather to include various modifications, equivalents, or substitutes of the embodiments.

[0023] In connection with the description of the drawings, similar reference numerals may be used for similar or related components.

[0024] The singular form of a noun corresponding to an item may include one or more of said items, unless the relevant context clearly indicates otherwise.

[0025] In this document, each of the phrases "A or B", "at least one of A and B", "at least one of A or B", "A, B, or C", "at least one of A, B, and C", and "at least one of A, B, or C" may include any one of the items listed together in that phrase, or all possible combinations thereof.

[0026] The term “and / or” includes any combination of a plurality of related described elements or any one of a plurality of related described elements.

[0027] Terms such as "first," "second," or "first" or "second" may be used simply to distinguish one component from another and do not qualify the components in any other respect (e.g., importance or order).

[0028] When a component (e.g., a first component) is referred to as being "coupled" or "connected" to another component (e.g., a second component), with or without the terms "functionally" or "communicatively," it means that the component can be connected to the other component directly (e.g., wired), wirelessly, or through a third component.

[0029] The terms “include” or “have” are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in this document, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0030] When a component is said to be “connected,” “coupled,” “supported,” or “in contact with” another component, this includes not only cases where the components are directly connected, coupled, supported, or in contact, but also cases where the components are indirectly connected, coupled, supported, or in contact through a third component.

[0031] When we say that a component is “on” another component, this includes not only cases where the component is in contact with the other component, but also cases where there is another component between the two components.

[0032] Hereinafter, an embodiment according to the present invention will be described with reference to the attached drawings.

[0033] Throughout the specification, the same reference numerals denote the same components. This specification does not describe all elements of the embodiments, and any content that is general in the technical field to which the present invention pertains or that overlaps between embodiments is omitted. The terms 'part, module, element, block' used in the specification may be implemented in software or hardware, and depending on the embodiments, multiple 'parts, modules, elements, blocks' may be implemented as a single component, or a single 'part, module, element, block' may include multiple components.

[0034] Throughout the specification, when a part is said to be "connected" to another part, this includes not only the case where it is directly connected, but also the case where it is indirectly connected to another component, and an indirect connection includes a connection via a wireless communication network or an electrical connection by wiring, soldering, etc.

[0035] Additionally, when a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0036] Throughout the specification, when we say that an element is "on" another element, this includes not only cases where the element is in contact with the other element, but also cases where another element exists between the two elements.

[0037] Throughout the specification, whenever a component is said to convey or transmit signals or data to another component, this does not preclude the existence of another component between that component and the other component through which it conveys or transmits, unless otherwise specifically stated.

[0038] Throughout the specification, ordinal expressions such as “first” and “second” are used to distinguish between multiple components, and the ordinal numbers used do not indicate the arrangement order, manufacturing order, or importance of the components.

[0039] Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0040] For each step, the identification code is used to refer to each step, and this identification code does not limit the order of each step, and each step may be performed in a different order than specified unless the context clearly indicates a specific order.

[0041] When phrases such as "at least one" follow a list of elements, they can modify the combination of elements. For example, the phrase "at least one of a, b, or c" can be interpreted to include 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.

[0042] Referring to the attached drawings below, an embodiment of a display module and a display device including the same according to one aspect is described in detail.

[0043] FIG. 1 is a perspective view showing an example of a display module and a display device including the same according to one embodiment of the present disclosure, and FIG. 2 is a drawing showing an example of a pixel array constituting a unit module of a display device according to one embodiment of the present disclosure.

[0044] According to one embodiment, the display device is a self-luminous display device in which light-emitting elements are arranged in each pixel, enabling each pixel to emit light on its own. Therefore, unlike liquid crystal display devices, it does not require components such as a backlight unit or liquid crystal layer, enabling a thin thickness, and its simple structure allows for various design changes.

[0045] In addition, a display device according to one embodiment may employ an inorganic light-emitting element, such as an inorganic light-emitting diode (ILD), as a light-emitting element arranged in each pixel. Inorganic light-emitting elements have a faster response speed than organic light-emitting elements, such as OLED (Organic Light Emitting Diode), and can implement high brightness with low power consumption.

[0046] In addition, unlike organic light-emitting devices, which are vulnerable to moisture and oxygen exposure, require a sealing process, and have low durability, the inorganic light-emitting device does not require a sealing process and is also durable. Hereinafter, the inorganic light-emitting device mentioned in the examples described below refers to an inorganic light-emitting diode.

[0047] In one embodiment, the inorganic light-emitting element employed in the display device may be a micro LED having a short side length of approximately 100 μm, tens of μm, or several μm. By employing micro LEDs in this manner, pixel sizes can be reduced and high resolution can be achieved even within the same screen size.

[0048] Furthermore, manufacturing LED chips in micron-scale sizes can address the inherent problem of inorganic materials breaking when bent. In other words, mounting micro LED chips on a flexible substrate prevents them from breaking even when the substrate bends, making flexible display devices possible.

[0049] Display devices employing micro LEDs can be applied to various fields by taking advantage of their ultra-small pixel size and thin thickness. For example, as illustrated in FIG. 1, a large-area screen can be implemented by tiling multiple display modules (10) equipped with multiple micro LEDs and fixing them to a housing (20). Such a large-area display device can be used as signage, electronic billboards, etc.

[0050] Meanwhile, the three-dimensional coordinate system of the XYZ axes illustrated in Fig. 1 is based on the display device (1), and the plane on which the screen of the display device (1) is located is the XZ plane, and the direction in which the image is output or the light-emitting direction of the inorganic light-emitting element is the +Y direction. Since the coordinate system is based on the display device (1), the same coordinate system can be applied whether the display device (1) is lying down or standing up.

[0051] Generally, the display device (1) is used in a standing position, and the user views the image from the front of the display device (1), so the +Y direction in which the image is output can be called the front, and the opposite direction can be called the rear.

[0052] In addition, the display device (1) is generally manufactured in a lying state. Therefore, it is also possible to refer to the -Y direction of the display device (1) as the downward direction and the +Y direction as the upward direction. That is, in the embodiment described below, the +Y direction may be referred to as the upward direction or forward, and the -Y direction may be referred to as the downward direction or rear.

[0053] Except for the top and bottom surfaces of a flat-type display device (1) or display module (10), the remaining four surfaces are all referred to as side surfaces, regardless of the position of the display device (1) or display module (10).

[0054] In the example of Fig. 1, a case is illustrated where a display device (1) includes a plurality of display modules to implement a large-area screen, but the embodiment of the display device (1) is not limited thereto. It is also possible for the display device (1) to be implemented as a TV, wearable device, portable device, PC monitor, etc., including a single display module (10).

[0055] Referring to FIG. 2, the display module (10) may include a plurality of pixels arranged in a two-dimensional manner, i.e., an M x N (M, N are integers greater than or equal to 2) array of pixels. FIG. 2 conceptually illustrates the pixel array, and it is to be understood that, in addition to the active area where pixels are arranged in the display module (10), a bezel area or wiring area where no image is displayed may also be located.

[0056] In the present embodiment, the fact that certain components are arranged two-dimensionally may include not only cases where the components are arranged on the same plane, but also cases where the components are arranged on different planes that are parallel to each other. Furthermore, cases where the components are arranged on the same plane do not necessarily require that the tops of the arranged components be located on the same plane, and cases where the tops of the arranged components are located on different planes that are parallel to each other may also be included.

[0057] A pixel (P) can be composed of at least three sub-pixels that output light of different colors. For example, a unit pixel (P) can be composed of three sub-pixels (SP(R), SP(G), SP(B)) corresponding to R, G, and B, respectively. Here, a red sub-pixel (SP(R)) can output red light, a green sub-pixel (SP(G)) can output green light, and a blue sub-pixel (SP(B)) can output blue light.

[0058] However, the pixel arrangement of FIG. 2 is merely an example that can be applied to a display module (10) and a display device (1) according to one embodiment, and the sub-pixels may be arranged along the Z-axis direction, may not be arranged in a row, and may be implemented with different sizes of the sub-pixels. A single pixel only needs to include multiple sub-pixels to implement various colors, and there are no restrictions on the size or arrangement of each sub-pixel.

[0059] In addition, a pixel (P) does not necessarily have to be composed of a red sub-pixel (SP(R)) that outputs red light, a green sub-pixel (SP(G)) that outputs green light, and a blue sub-pixel (SP(B)) that outputs blue light, and it is also possible to include a sub-pixel that outputs yellow light or white light. In other words, there are no restrictions on the color or type of light output from each sub-pixel, or the number of sub-pixels.

[0060] Figure 3 is a block diagram of a display device according to one embodiment.

[0061] As described above with reference to FIG. 1, a display device (1) according to one embodiment may include a plurality of display modules (10-1, 10-2, ..., 10-n, where n is an integer greater than or equal to 2), and may include a main controller (300) and a timing controller (500) that control a plurality of display modules (10), a communication unit (430) that communicates with an external device, a source input unit (440) that receives a source image, a speaker (410) that outputs sound, and an input unit (420) that receives a command for controlling the display device (1) from a user.

[0062] The input unit (420) may include a button or a touch pad provided in one area of ​​the display device (1), and when the display device (1) is implemented as a touch screen, the input unit (420) may include a touch pad provided on the front of the display device (1). In addition, the input unit (420) may also include a remote controller.

[0063] The input unit (420) can receive various commands from the user to control the display device (1), such as turning the display device (1) on / off, adjusting the volume, adjusting the channel, adjusting the screen, and changing various settings.

[0064] The speaker (410) may be provided in one area of ​​the main body (20), or a separate speaker module physically separated from the main body (20) may be further provided.

[0065] The communication unit (430) can communicate with a relay server or other electronic devices to send and receive necessary data. The communication unit (430) can adopt at least one of various wireless communication methods such as 3G (3rd Generation), 4G (4th Generation), wireless LAN, Wi-Fi, Bluetooth, Zigbee, WFD (Wi-Fi Direct), UWB (Ultra wideband), Infrared Data Association (IrDA), Bluetooth Low Energy (BLE), Near Field Communication (NFC), and Z-Wave. In addition, it is also possible to adopt a wired communication method such as PCI (Peripheral Component Interconnect), PCI-express, and USB (Universe Serial Bus).

[0066] The source input unit (440) can receive a source signal input from a set-top box, USB, antenna, etc. Accordingly, the source input unit (440) can include at least one selected from a group of source input interfaces including an HDMI cable port, a USB port, an antenna, etc.

[0067] The source signal received by the source input unit (440) can be processed by the main controller (300) and converted into a form that can be output from the display panel (100, see FIG. 4) and speaker (410).

[0068] The main controller (300) and the timing controller (500) may include at least one memory that stores a program and various data for performing the operations described below, and at least one processor that executes the stored program.

[0069] The main controller (300) can process a source signal input through the source input unit (440) to generate a video signal corresponding to the input source signal.

[0070] For example, the main controller (300) may include a source decoder, a scaler, an image enhancer, and a graphics processor. The source decoder may decode a source signal compressed in a format such as MPEG, and the scaler may output image data of a desired resolution through resolution conversion.

[0071] Image enhancers can improve the image quality of image data by applying various correction techniques. The graphics processor can distinguish pixels of image data into RGB data and output them along with control signals, such as a synchronization signal for display timing on the display panel (100). In other words, the main controller (300) can output image data and control signals corresponding to the source signal.

[0072] The operation of the main controller (300) described above is only an example applicable to the display device (1), and it is also possible to perform other operations or omit some of the operations described above.

[0073] The image data and control signals output from the main controller (300) can be transmitted to the timing controller (500).

[0074] The timing controller (500) can convert image data transmitted from the main controller (300) into image data in a form that can be processed by the driver IC (200, see FIG. 4) and generate various control signals, such as timing control signals, necessary to display the image data on the display panel (100).

[0075] Although a display device (1) according to one embodiment does not necessarily have to include a plurality of display modules (10), in the embodiment described below, for the sake of specific explanation, a display device (1) including a plurality of display modules (10) will be used as an example to specifically explain the operation of each component.

[0076] FIG. 4 is a block diagram illustrating a configuration of a display module included in a display device according to one embodiment, and FIG. 5 is a drawing conceptually illustrating a method of driving each pixel in a display module according to one embodiment.

[0077] Referring to FIG. 4, each of the plurality of display modules (10-1, 10-2, ..., 10-n) may include a display panel (100) that displays an image and a driver IC (200) that drives the display panel (100).

[0078] The driver IC (200) can generate a driving signal so that the display panel (100) can display an image based on image data and a timing control signal transmitted from the timing controller (500).

[0079] The driving signal generated by the driver IC (200) may include a gate signal and a data signal, and the generated driving signal is input to the display panel (100).

[0080] As described above, the display device (1) according to one embodiment is a self-luminous display device. Accordingly, an inorganic light-emitting element (120) that emits red, green, or blue light may be arranged in each sub-pixel.

[0081] The inorganic light-emitting element (120) arranged in each sub-pixel can be driven by an AM (Active Matrix) method or a PM (Passive Matrix) method. However, in the embodiment described below, for the sake of specific explanation, a case in which the inorganic light-emitting element (120) is driven by an AM method will be described as an example.

[0082] Referring to FIG. 5, the driver IC (200) may include a scan driver (210) and a data driver (220). The scan driver (210) may output a gate signal for turning on / off a sub-pixel, and the data driver (220) may output a data signal for implementing an image.

[0083] The scan driver (210) can generate a gate signal based on a timing control signal transmitted from the timing controller (500), and the data driver (220) can generate a data signal based on image data transmitted from the timing controller (500).

[0084] The display module (10) may include a pixel circuit (110) for individually controlling each inorganic light-emitting element (120), and a gate signal output from a scan driver (210) and a data signal output from a data driver (220) may be input to the pixel circuit (110).

[0085] For example, when a gate voltage (VGATE), a data voltage (VDATA), and a power voltage (VDD) are input to a pixel circuit (110), the pixel circuit (110) can output a driving current (CD) for driving an inorganic light-emitting element (120).

[0086] The driving current (CD) output from the pixel circuit (110) can be input to the inorganic light-emitting element (120), and the inorganic light-emitting element (120) can emit light by the input driving current (CD) to implement an image.

[0087] FIG. 6 is a circuit diagram schematically illustrating a pixel circuit for controlling pixels in a display module according to one embodiment of the present disclosure.

[0088] Referring to the example of FIG. 6, the pixel circuit (110) may include a thin film transistor (TR1, TR2) and a capacitor (Cst) that switch or drive an inorganic light emitting element (120).

[0089] In the present disclosure, the inorganic light-emitting element (120) included in the pixel circuit (110) may include a plurality of LEDs (120). These plurality of LEDs (120) may include a plurality of LEDs (120) connected in series with each other or a plurality of LEDs (120) connected in parallel with each other.

[0090] For example, the thin film transistors (TR1, TR2) may include a switching transistor (TR1) and a driving transistor (TR2), and the switching transistor (TR1) and the driving transistor (TR2) may be implemented as PMOS type transistors. However, the embodiments of the display module (10) and the display device (1) are not limited thereto, and it is also possible for the switching transistor (TR1) and the driving transistor (TR2) to be implemented as NMOS type transistors.

[0091] Additionally, the thin film transistors (TR1, TR2) may be LTPS (Low Temperature Polycrystalline Silicon) thin film transistors or oxide thin film transistors. Furthermore, the thin film transistors may be a-Si thin film transistors or single-crystal thin film transistors.

[0092] For a specific explanation, the following embodiments will be described using an example of a case implemented with an LTPS PMOS type transistor.

[0093] The gate electrode of the switching transistor (TR1) is connected to the scan driver (210), the source electrode is connected to the data driver (220), and the drain electrode is connected to one end of the capacitor (Cst) and the gate electrode of the driving transistor (TR2). The other end of the capacitor (Cst) can be connected to the first power source (610).

[0094] Additionally, the source electrode of the driving transistor (TR2) is connected to the first variable power supply (610) that supplies the power voltage (VDD), and the drain electrode is connected to the anode of the inorganic light emitting element (120).

[0095] The cathode of the inorganic light emitting element (120) can be connected to a second variable power supply (620) that supplies a reference voltage (VSS). The reference voltage (VSS) is a voltage at a lower level than the power supply voltage (VDD), and a ground voltage or the like can be used to provide grounding.

[0096] Here, the first variable power supply unit (610) and the second variable power supply unit (620) can change the power supply voltage (VDD) and reference voltage (VSS) supplied as described later.

[0097] The pixel circuit (110) of the above-described structure can operate as follows. First, when a gate voltage (VGATE) is applied from a scan driver (210) and the switching transistor (TR1) is turned on, a data voltage (VDATA) applied from a data driver (220) can be transmitted to one end of a capacitor (Cst) and the gate electrode of a driving transistor (TR2).

[0098] A voltage corresponding to the gate-source voltage of the driving transistor (TR2) can be maintained for a certain period of time by the capacitor (Cst). The driving transistor (TR2) can cause the inorganic light-emitting element (120) to emit light by applying a driving current (CD) corresponding to the gate-source voltage to the anode of the inorganic light-emitting element (120).

[0099] However, the structure of the pixel circuit (131) described above is only an example applicable to the display module (10) according to one embodiment, and in addition to the example described above, various circuit structures for switching and driving a plurality of inorganic light-emitting elements (120) may be applied.

[0100] In addition, the present embodiment does not place any restrictions on the brightness control method of the inorganic light-emitting element (120). The brightness of the inorganic light-emitting element (120) can be controlled by one of various methods, such as the PAM (Pulse Amplitude Modulation) method, the PWM (Pulse Width Modulation) method, and a hybrid method combining the PAM method and the PWM method. The structure of the pixel circuit (110) can also vary depending on the brightness control method.

[0101] The overall structure and operation of the pixel circuit (110) have been described above. Below, a variable power supply unit that includes multiple LEDs and adjusts the supply voltage to compensate for voltage drops will be described.

[0102] As described above, the disclosed invention may include a plurality of pixel circuits (110) provided on a substrate.

[0103] Each of these plurality of pixel circuits (110) may include a plurality of LEDs (120) connected in series or in parallel, a driving TFT (TR2) for applying a driving current to the plurality of LEDs (120), and may further include a variable power supply unit (610, 620) for adjusting the voltage supplied to the TFT to compensate for the voltage drop caused by the plurality of LEDs.

[0104] As described above, this variable power supply unit may include a first variable power supply unit (610) that supplies a power voltage (VDD) and a second variable power supply unit (620) that supplies a reference voltage (VSS). That is, the first variable power supply unit (610) may be arranged to change the supplied power voltage, and the second variable power supply unit (620) may be arranged to change the supplied reference voltage.

[0105] FIG. 7 is a drawing showing a connection structure for each LED according to one embodiment of the present disclosure, FIG. 8 is a drawing showing a connection structure of a power supply according to one embodiment of the present disclosure, and FIG. 9 is a drawing showing efficiency according to current flowing through an LED according to one embodiment of the present disclosure.

[0106] The plurality of LEDs (120) included in the pixel circuit (110) may include at least one of a plurality of red (RED) LEDs, a plurality of blue (BLUE) LEDs, and a plurality of green (GREEN) LEDs.

[0107] That is, the pixel circuit (110) may include a plurality of red (RED) LEDs, a plurality of blue (BLUE) LEDs, and a plurality of green (GREEN) LEDs. Alternatively, LEDs of different colors may be included together. As described above, the distinction between red LEDs, green LEDs, and blue LEDs is merely an example, and LEDs of various colors may be included.

[0108] In a pixel circuit (110) according to one embodiment, when a plurality of LEDs (120) are a plurality of red LEDs, the plurality of red LEDs may be connected in series with each other as shown in Fig. 7(a).

[0109] Because the red LED has a high luminous efficiency when the current is high, multiple red LEDs (120-1, 120-2, 120-3) can be connected in series so that high current can flow to each LED.

[0110] At this time, the voltage supplied from the variable power supply can be adjusted to compensate for the voltage drop equivalent to the sum (Vled * N) of the voltages (Vled) applied to each of the N red LEDs connected in series due to the high current flowing through them.

[0111] In a pixel circuit (110) according to one embodiment, when a plurality of LEDs are green LEDs, the plurality of green LEDs may be connected in parallel to each other as shown in Fig. 7(b).

[0112] Because the green LED has a high luminous efficiency when compared to the red LED due to its relatively low current characteristics, multiple green LEDs (120-1, 120-2, 120-3) can be connected in parallel so that low current can flow to each LED.

[0113] In a pixel circuit (110) according to one embodiment, when a plurality of LEDs are blue LEDs, the plurality of blue LEDs can be connected in parallel to each other as shown in Fig. 7(b).

[0114] Because the blue LED has a high luminous efficiency when compared to the red LED due to its characteristics, multiple blue LEDs (120-1, 120-2, 120-3) can be connected in parallel so that low current can flow to each LED.

[0115] At this time, since the current input to the LED increases due to current division caused by the parallel connection, a voltage drop equivalent to the increased LED input current may occur. The variable power supply can adjust the voltage supplied by the variable power supply to compensate for the voltage drop caused by this increased current.

[0116] As mentioned above, the compensation voltage may differ when multiple LEDs are connected in series or in parallel. Accordingly, different variable power supplies may be used depending on the arrangement of the LEDs.

[0117] These variable power supplies (610, 620) can be independently connected to multiple pixel circuits (110).

[0118] For example, as illustrated in (a) of FIG. 8, a plurality of first variable power supply units (610-1, 610-2, 610-3) and a plurality of second variable power supply units (620-1, 620-2, 620-3) may be configured in an independent form, each connected to a pixel circuit (110) arranged in the same column.

[0119] In this case, the first variable power supply unit a (610-1) can supply a power voltage to pixel circuits (110) provided in the first column on the TFT substrate, and the second variable power supply unit a (620-1) can supply a reference voltage to pixel circuits (110) provided in the first column on the TFT substrate.

[0120] Additionally, the variable power supply (610, 620) may be commonly connected to multiple pixel circuits (110).

[0121] For example, as illustrated in (b) of FIG. 8, one first variable power supply unit (610) and one second variable power supply unit (620) can supply a power voltage and a reference voltage to a plurality of pixel circuits (110) on a TFT substrate, respectively.

[0122] Referring to Figure 9, it can be seen that the red LED is most efficient at high currents of 100 [uA] or more, and the blue and green LEDs are most efficient at relatively low currents of 100 [uA] or less.

[0123] When the current flowing through multiple LEDs is approximately 150 [uA], in the case of multiple red LEDs (120-1, 120-2, 120-3) connected in series, a current of 150 [uA] will flow to each LED, thereby achieving high efficiency.

[0124] Also, in the case of N blue LEDs or green LEDs (120-1, 120-2, 120-3) connected in parallel under the same current situation, a current of 150 / N[uA] will flow to each LED, which will enable high efficiency.

[0125] As shown in Fig. 7, when three LEDs are connected in series or in parallel, in the case of red LEDs connected in series, 150 [uA] of current flows through each LED, and in the case of blue LEDs or green LEDs connected in parallel, 50 [uA] of current flows through each LED, so that high luminous efficiency suitable for the characteristics of each LED can be achieved.

[0126] FIG. 10 is a diagram for explaining voltage drop by multiple LEDs according to one embodiment of the present disclosure.

[0127] FIG. 10 illustrates an example in which multiple LEDs (120) are connected in series, but is not limited thereto and may also include a case in which multiple LEDs are connected in parallel or in a mixed manner in series and parallel.

[0128] The variable power supply (610, 620) can adjust the voltage supplied to the driving TFT to compensate for the voltage drop due to the LED voltage and driving current of a plurality of red LEDs (120) connected in series.

[0129] That is, the voltage supplied from the variable power supply can be adjusted to compensate for the voltage (Vled * N) of the sum of the voltages (Vled) applied to each of N red LEDs connected in series and the voltage drop (Vdrop1, Vdrop2) due to the high current flowing through the red LED. In addition, the variable power supply (610, 620) can also adjust the voltage supplied to compensate for the voltage applied to the driving TFT.

[0130] The first variable power supply unit (610) can adjust the power voltage supplied within the range of Vdd to Vdd + first voltage, and the second variable power supply unit (620) can adjust the reference voltage supplied within the range of Vss - second voltage to Vss.

[0131] Here, the first voltage and the second voltage can be set to appropriate voltage values ​​that can compensate for the voltage drop.

[0132] These variable power supply units (610, 620) can adjust the voltage supplied for each frame to compensate for voltage drops. That is, the variable voltage of the variable power supply units (610, 620) operates at a specific frequency and can compensate for voltage drops due to screen changes for each frame.

[0133] In addition, the variable power supply unit (610, 620) can adjust the voltage supplied to the driving TFT to compensate for the voltage drop due to the LED voltage and driving current caused by the multiple green LEDs or multiple blue LEDs connected in parallel. In addition, the variable power supply unit (610, 620) can also adjust the voltage supplied to compensate for the voltage applied to the driving TFT.

[0134] That is, the voltage supplied from the variable power supply can be adjusted to compensate for the voltage (Vled) of the sum of the voltages applied to each of N blue LEDs or green LEDs connected in parallel and the voltage drop (Vdrop1, Vdrop2) due to the current flowing through the blue LED or green LED.

[0135] The first variable power supply unit (610) can adjust the power voltage supplied within the range of Vdd to Vdd + first voltage, and the second variable power supply unit (620) can adjust the reference voltage supplied within the range of Vss - second voltage to Vss.

[0136] A display module according to one embodiment includes a substrate; a plurality of pixel circuits provided on the substrate; each of the plurality of pixel circuits may include a plurality of LEDs connected in series or in parallel; a driving TFT for applying a driving current to the plurality of LEDs; and a variable power supply for adjusting a voltage supplied to the driving TFT to compensate for a voltage drop caused by the plurality of LEDs.

[0137] According to the present disclosure, high brightness and high efficiency can be achieved by arranging multiple LEDs in a pixel circuit in series or parallel according to LED characteristics and compensating for voltage drop according to multiple LEDs through a variable power supply.

[0138] The plurality of LEDs may include at least one of a plurality of red (RED) LEDs, a plurality of blue (BLUE) LEDs, and a plurality of green (GREEN) LEDs.

[0139] The above multiple red LEDs can be connected in series with each other.

[0140] The above variable power supply unit can adjust the voltage supplied to the driving TFT to compensate for the voltage drop due to the LED voltage and the driving current of the plurality of red LEDs connected in series.

[0141] The plurality of green LEDs or the plurality of blue LEDs may be connected in parallel with each other.

[0142] The above variable power supply unit can adjust the voltage supplied to the driving TFT to compensate for the LED voltage caused by the plurality of green LEDs or the plurality of blue LEDs connected in parallel and the voltage drop caused by the driving current.

[0143] The variable power supply unit may include a first variable power supply unit that supplies a power voltage (VDD); and a second variable power supply unit that supplies a reference voltage (VSS).

[0144] The above variable power supply unit can adjust the voltage supplied to the driving TFT to compensate for the voltage drop caused by the plurality of LEDs for each frame.

[0145] A display device according to one embodiment includes a frame; a plurality of display modules arranged in a two-dimensional matrix on the frame; each of the plurality of display modules includes a substrate; a plurality of pixel circuits provided on the substrate; and each of the plurality of pixel circuits may include a plurality of LEDs connected in series or in parallel; a driving TFT for applying a driving current to the plurality of LEDs; and a variable power supply for adjusting a voltage supplied to the driving TFT to compensate for a voltage drop caused by the plurality of LEDs.

[0146] The plurality of LEDs may include at least one of a plurality of red (RED) LEDs, a plurality of blue (BLUE) LEDs, and a plurality of green (GREEN) LEDs.

[0147] The above multiple red LEDs can be connected in series with each other.

[0148] The above variable power supply unit can adjust the voltage supplied to the driving TFT to compensate for the voltage drop due to the LED voltage and the driving current of the plurality of red LEDs connected in series.

[0149] The plurality of green LEDs or the plurality of blue LEDs may be connected in parallel with each other.

[0150] The above variable power supply unit can adjust the voltage supplied to the driving TFT to compensate for the LED voltage caused by the plurality of green LEDs or the plurality of blue LEDs connected in parallel and the voltage drop caused by the driving current.

[0151] The variable power supply unit may include a first variable power supply unit that supplies a power voltage (VDD); and a second variable power supply unit that supplies a reference voltage (VSS).

[0152] The above variable power supply unit can adjust the voltage supplied to the driving TFT to compensate for the voltage drop caused by the plurality of LEDs for each frame.

[0153] According to the disclosed invention, high brightness and high efficiency can be achieved by arranging multiple LEDs in a pixel circuit in series or parallel according to LED characteristics and compensating for voltage drop according to multiple LEDs through a variable power supply.

[0154] Meanwhile, the disclosed embodiments may be implemented in the form of a recording medium storing computer-executable instructions. The instructions may be stored in the form of program code, and when executed by a processor, may generate program modules to perform the operations of the disclosed embodiments. The recording medium may be implemented as a computer-readable recording medium.

[0155] Computer-readable storage media include all types of storage media that store instructions that can be deciphered by a computer. Examples include read-only memory (ROM), random access memory (RAM), magnetic tape, magnetic disks, flash memory, and optical data storage devices.

[0156] The disclosed embodiments have been described with reference to the attached drawings as described above. Those skilled in the art will understand that the present invention can be implemented in forms other than the disclosed embodiments without altering the technical spirit or essential features of the present invention. The disclosed embodiments are illustrative and should not be construed as limiting.

Claims

1. Substrate; A plurality of pixel circuits provided on the substrate; Each of the above plurality of pixel circuits, Multiple LEDs connected in series or parallel; A driving TFT for applying a driving current to the plurality of LEDs; and A display module including a variable power supply unit that adjusts the voltage supplied to the driving TFT to compensate for voltage drop caused by the plurality of LEDs.

2. In paragraph 1, The above plurality of LEDs are, A display module comprising at least one of a plurality of red (RED) LEDs, a plurality of blue (BLUE) LEDs, and a plurality of green (GREEN) LEDs.

3. In paragraph 2, A display module in which the above plurality of red LEDs are connected in series with each other.

4. In paragraph 3, The above variable power supply unit, A display module that adjusts the voltage supplied to the driving TFT to compensate for the voltage drop due to the LED voltage and the driving current of the plurality of red LEDs connected in series.

5. In paragraph 2, A display module in which the plurality of green LEDs or the plurality of blue LEDs are connected in parallel with each other.

6. In paragraph 5, The above variable power supply unit, A display module that adjusts the voltage supplied to the driving TFT to compensate for the voltage drop due to the LED voltage and the driving current by the plurality of green LEDs or the plurality of blue LEDs connected in parallel.

7. In paragraph 1, The above variable power supply unit, Power voltage (V) DD ) a first variable power supply; and Reference voltage (V) SS ) and a second variable power supply unit; a display module including the same.

8. In paragraph 1, The above variable power supply unit, A display module that adjusts the voltage supplied to the driving TFT to compensate for voltage drop caused by the plurality of LEDs on a frame-by-frame basis.

9. Frame; A plurality of display modules arranged in a two-dimensional matrix in the above frame; Each of the above plurality of display modules, substrate; A plurality of pixel circuits provided on the substrate; Each of the above plurality of pixel circuits, Multiple LEDs connected in series or parallel; A driving TFT for applying a driving current to the plurality of LEDs; and A display device including a variable power supply unit that adjusts the voltage supplied to the driving TFT to compensate for voltage drop caused by the plurality of LEDs.

10. In paragraph 9, The above plurality of LEDs are, A display device comprising at least one of a plurality of red (RED) LEDs, a plurality of blue (BLUE) LEDs, and a plurality of green (GREEN) LEDs.

11. In paragraph 10, A display device in which the above plurality of red LEDs are connected in series with each other.

12. In paragraph 11, The above variable power supply unit, A display device that adjusts the voltage supplied to the driving TFT to compensate for the voltage drop due to the LED voltage and the driving current by the plurality of red LEDs connected in series.

13. In paragraph 10, A display device in which the plurality of green LEDs or the plurality of blue LEDs are connected in parallel with each other.

14. In paragraph 13, The above variable power supply unit, A display device that adjusts the voltage supplied to the driving TFT to compensate for the voltage drop due to the LED voltage and the driving current by the plurality of green LEDs or the plurality of blue LEDs connected in parallel.

15. In paragraph 9, The above variable power supply unit, Power voltage (V) DD ) a first variable power supply; and Reference voltage (V) SS A display device including a second variable power supply unit that supplies a voltage;

Images