KR20080075662A - Light emitting device and display using the light emitting device, the driving method of the light emitting device, and the method of the display - Google Patents

Abstract

A light emission device, a display device using the same, a method for driving the light emission device, and a method for driving the display device are provided to obtain a high response speed by using scan reset signals and light emission reset signals, thereby preventing the distortion of signals. A light emission device comprises a backlight unit(40'). The backlight unit includes a plurality of scan lines(S1,S2-Sp) for transmitting a plurality of first scan signals, a plurality of column lines(C1,C2,C3-Cq) for transmitting a plurality of first light emission data signals, and a plurality of backlight unit pixels(EPX) defined by the scan lines and the column lines. The first scan signals include scan reset signals, and the first light emission data signals include light emission reset signals. The first scan signal includes a scan-on signal having a first level during a first period, and a scan reset signal having a second level during a second period. A polarity of the first level is different from a polarity of the second level.

Description

LIGHT EMITTING DEVICE AND DISPLAY USING THE LIGHT EMITTING DEVICE, THE DRIVING METHOD OF THE LIGHT EMITTING DEVICE, AND THE METHOD OF THE DISPLAY}

1 is an exploded perspective view of a liquid crystal display according to a first exemplary embodiment of the present invention.

FIG. 2 is a partially cutaway perspective view of the liquid crystal panel assembly shown in FIG. 1.

3 is a partially cutaway perspective view of the backlight unit according to the first embodiment of the present invention.

4 is a partial cross-sectional view of the fourth substrate and the electron emission unit illustrated in FIG. 3.

5 is a partial plan view of an electron emission unit of a backlight unit according to a second embodiment of the present invention.

6 is a partial cutaway perspective view of a backlight unit according to a third exemplary embodiment of the present invention.

7 is a block diagram illustrating a display device according to a third exemplary embodiment of the present invention.

8 is a waveform illustrating a scan on signal and a first scan signal according to a third embodiment of the present invention.

9 is a waveform illustrating a light emission data on signal and a first light emission data on signal according to a third embodiment of the present invention.

The present invention relates to a display device, and more particularly, to a display device including a backlight unit operating in synchronization with a display image.

A liquid crystal display device, which is a type of flat panel display device, is a display device that realizes a predetermined image by varying light transmittance for each pixel by using dielectric anisotropy of a liquid crystal whose twist angle changes according to an applied voltage. Such a liquid crystal display device has advantages such as light weight, thickness, and low power consumption compared to a cathode ray tube, which is a typical image display device.

The liquid crystal display basically includes a liquid crystal panel assembly and a backlight unit positioned behind the liquid crystal panel assembly to provide light to the liquid crystal panel assembly.

When the liquid crystal panel assembly is composed of an active liquid crystal panel assembly, the liquid crystal panel assembly includes a pair of transparent substrates, a liquid crystal layer positioned between the transparent substrates, a polarizing plate disposed on the outer surfaces of the transparent substrates, and either transparent A color filter that provides red, green, and blue colors to the common electrode provided on the inner surface of the substrate, the pixel electrodes and switching elements provided on the inner surface of the other transparent substrate, and the three sub-pixels constituting one pixel. And the like.

The liquid crystal panel assembly receives light emitted from the backlight unit and transmits or blocks the light by the action of the liquid crystal layer to realize a predetermined image.

The backlight unit may be classified according to the type of light source, and one of them is known as a cold cathode fluorescent lamp (CCFL). Since the CCFL is a line light source, the light generated by the CCFL can be evenly dispersed toward the liquid crystal panel assembly through the optical members such as the diffusion sheet, the diffusion plate, and the prism sheet.

However, in the CCFL method, since light generated in the CCFL passes through the optical member, significant light loss occurs. In general, in the CCFL type liquid crystal display, the light passing through the liquid crystal panel assembly is known to correspond to about 3 to 5% of the CCFL generated light. In addition, the CCFL type backlight unit consumes a large portion of the total power consumption of the liquid crystal display due to large power consumption, and it is difficult to apply to a large liquid crystal display device having a size of 30 inches or more because of the large area of the CCFL structure.

As a conventional backlight unit, a light emitting diode (LED) method is known. A plurality of LEDs are usually provided as a point light source, and are combined with optical members such as a reflective sheet, a light guide plate, a diffusion sheet, a diffusion plate, and a prism sheet to constitute a backlight unit. This LED method has the advantages of fast response speed and excellent color reproducibility, but has a disadvantage of high price and large thickness.

As such, the conventional backlight unit has its own problems depending on the type of light source. In addition, since the conventional backlight unit is always turned on at a constant brightness when the liquid crystal display is driven, it is difficult to meet the image quality improvement required for the liquid crystal display.

For example, when the liquid crystal panel assembly displays an arbitrary screen including a bright portion and a dark portion in accordance with an image signal, the backlight unit displays the liquid crystal panel pixels portion displaying the bright portion and the liquid crystal panel pixels displaying the dark portion. If the light of different intensity is provided to the part, it is possible to realize a screen having excellent dynamic contrast.

In addition, the drive of the backlight unit used a simple pulse. At this time, the time constant is increased by the resistor and the capacitor constituting the backlight unit. To prevent this, reducing the resistance increases the capacitor by that area, reducing the metal to reduce the capacitor increases the resistance by that area, and may cause arcing due to exposed insulation. .

Accordingly, the present invention has been made to solve the above-described problems, a fast response speed can be obtained, and a light emitting device capable of preventing the occurrence of arcing (arcing), a display device using the same, a method of driving the light emitting device and The present invention provides a method of driving a display device.

Another object of the present invention is to provide a light emitting device capable of preventing unnecessary electron emission, a display device using the same, a method of driving the light emitting device, and a method of driving the display device.

In order to achieve the above object, a display device according to an aspect of the present invention includes a plurality of gate lines for transmitting a plurality of gate signals, a plurality of data lines for transmitting a plurality of data signals, and a plurality of gate lines and the plurality of gate lines. A panel assembly including a plurality of pixels defined by a data line, a plurality of scan lines transferring a plurality of first scan signals, a plurality of column lines transferring a plurality of first light emitting data signals, and the plurality of scan lines And a backlight unit having a plurality of first backlight unit pixels defined by the plurality of column lines, wherein the first scan signal includes a scan reset signal. The first backlight unit pixel corresponds to a plurality of pixels of the panel assembly, and emits light with luminance corresponding to the highest gray level among the plurality of pixels. In this case, the first scan signal may include a scan on signal having a first level during a first period, and a scan reset signal having a second level during a second period, wherein the polarity of the first level and the second level is different. This is different from each other. The scan reset signal has the same polarity as the charge formed by the scan on signal at the first level. The plurality of first backlight unit pixels are electron emission devices that emit light due to voltage differences between the plurality of first scan signals and the plurality of first emission data signals.

According to another aspect of the present invention, a display device includes a plurality of gate lines for transmitting a plurality of gate signals, a plurality of data lines for transmitting a plurality of data signals, and a plurality of gate lines and the plurality of data lines. A panel assembly including a plurality of pixels, a plurality of scan lines transferring a plurality of first scan signals, a plurality of column lines transferring a plurality of first light emitting data signals, the plurality of scan lines and the plurality of column lines And a backlight unit having a plurality of first backlight unit pixels defined by the first emission data signal. The first backlight unit pixel corresponds to a plurality of pixels of the panel assembly, and emits light with luminance corresponding to the highest gray level among the plurality of pixels. In this case, the first light emission data signal includes a light emission data on signal having a first level during a first period, and a light emission reset signal having a second level during a second period, wherein the first level and the second level are provided. Have different polarities. The light emission reset signal has the same polarity as the charge formed by the light emission data on signal of the first level. The plurality of first backlight unit pixels are electron emission devices that emit light due to voltage differences between the plurality of first scan signals and the plurality of first emission data signals.

According to another aspect of the present invention, a light emitting device includes a plurality of scan lines for transmitting a plurality of first scan signals, a plurality of column lines for transmitting a plurality of first light emission data signals, and a plurality of scan lines and the plurality of scan lines. And a backlight unit having a plurality of backlight unit pixels defined by a column line, wherein the first scan signal includes a scan reset signal and the first emission data signal includes a light emission reset signal. In this case, the first scan signal may include a scan on signal having a first level during a first period, and a scan reset signal having a second level during a second period, wherein the polarity of the first level and the second level is different. This is different from each other. The scan reset signal has the same polarity as the charge formed by the scan on signal at the first level. The first light emitting data signal includes a light emitting data on signal having a third level during a first period, and a light emitting reset signal having a fourth level during a second period, wherein the third level and the fourth level have polarities. This is different from each other. The light emission reset signal has the same polarity as the charge formed by the light emission data on signal of the third level.

According to still another aspect of the present invention, there is provided a method of driving a display device, the method comprising: a panel assembly displaying an image, and a backlight unit configured to supply a backlight to the panel assembly and include a plurality of scan lines and a plurality of column lines. A method of driving a display device, the method comprising: (a) transmitting a scan on signal to a first scan line of the plurality of scan lines, (b) synchronizing a light emitting data on signal to a first column in synchronization with the scan on signal; And transmitting (c) a scan reset signal to the first scan line and a light emission reset signal to the first column line. The panel assembly includes a plurality of pixels, the backlight unit includes a plurality of backlight unit pixels, and a first backlight unit pixel among the plurality of backlight unit pixels is a plurality of pixels of the panel assembly. And emit light at a luminance corresponding to the highest gray level among the plurality of pixels. In this case, step c) includes the scan on signal having a first level during a first period, and the scan reset signal having a second level during a second period, wherein Wherein the polarity is different from each other, the light emission data on signal having a third level during the first period, and the light emission reset signal having the fourth level during the second period, and wherein the polarity of the third level and the fourth level is different from each other. Are different.

A method of driving a light emitting device according to another aspect of the present invention, the method comprising: (a) transmitting a scan on signal to a first scan line of a plurality of scan lines, and (b) synchronizing light emission data on the scan on signal Delivering a signal to a first column line, and (c) delivering a scan reset signal to the first scan line and a light emission reset signal to the first column line. In this case, step c) includes the scan on signal having a first level during a first period, and the scan reset signal having a second level during a second period, wherein Wherein the polarity is different from each other, the light emission data on signal having a third level during the first period, and the light emission reset signal having the fourth level during the second period, and wherein the polarity of the third level and the fourth level is different from each other. Are different.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention. Like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is "connected" to another part, this includes not only the "directly connected" but also the "electrically connected" between other elements in between. In addition, when a part is said to "include" a certain component, this means that it may further include other components, except to exclude other components unless otherwise stated.

1 is an exploded perspective view of a liquid crystal display according to a first exemplary embodiment of the present invention.

Referring to the drawings, the liquid crystal display device 100 of the present embodiment has a liquid crystal panel assembly 10 having arbitrary pixels along the row direction and the column direction, and smaller than the liquid crystal panel assembly 10 along the row direction and the column direction. And a backlight unit 40 having a number of pixels and positioned behind the liquid crystal panel assembly 10 to provide light to the liquid crystal panel assembly 10.

Here, the row direction may be defined as one direction of the liquid crystal display 100, for example, a horizontal direction of the screen implemented by the liquid crystal panel assembly 10 (for example, the x-axis direction in the drawing), and the column direction may be defined as the liquid crystal display. Another direction of 100 may be defined as, for example, a vertical direction (for example, y-axis direction in the drawing) of the screen implemented by the liquid crystal panel assembly 10.

The number of pixels of the liquid crystal panel assembly 10 and the number of pixels of the backlight unit 40 in the row direction are referred to as M and M ', respectively, and the number of pixels and the backlight unit of the liquid crystal panel assembly 10 in the column direction ( When the number of pixels 40 is N and N ', respectively, the resolution of the liquid crystal panel assembly 10 may be expressed as M x N, and the resolution of the backlight unit 40 may be expressed as M' x N '.

In the present exemplary embodiment, M and N representing the number of pixels of the liquid crystal panel assembly 10 may be defined as integers of 240 or more, respectively, and M 'and N' representing the number of pixels of the backlight unit 40 are 2 to 99, respectively. Can be defined as any one of the integers. The backlight unit 40 includes a self-luminous display panel having a resolution of M 'x N'.

Thus, one pixel of the backlight unit 40 is positioned corresponding to two or more pixels of the liquid crystal panel assembly 10. In addition, the pixels of the backlight unit 40 are individually controlled on / off and light emission intensity by driving electrodes arranged in a matrix form, for example, scan electrodes and data electrodes positioned in directions perpendicular to each other.

In this embodiment, one pixel of the backlight unit 40 is formed of a field emission array (FEA) type electron emission device.

The FEA type electron emission device includes a scan electrode and a data electrode, an electron emission part and a fluorescent layer electrically connected to any one of the scan electrode and the data electrode. The electron emission part may be made of a material having a low work function or a high aspect ratio, for example, a carbon-based material or a nanometer (nm) size material.

The FEA type electron emitting device forms an electric field around the electron emitting part by using the voltage difference between the scan electrode and the data electrode to emit electrons therefrom, and excites the fluorescent layer with the emitted electrons to display visible light having an intensity corresponding to the electron beam emission amount. Release.

FIG. 2 is a partially cutaway perspective view of the liquid crystal panel assembly shown in FIG. 1.

Referring to the drawings, the liquid crystal panel assembly 10 includes a transparent first substrate 12 and a second substrate 14 disposed opposite to each other, and a liquid crystal injected between the first substrate 12 and the second substrate 14. A layer 16, a common electrode 18 located on an inner surface of the first substrate 12, pixel electrodes 20 and switching elements 22 located on an inner surface of the second substrate 14. do. Sealing members (not shown) are positioned at edges of the first substrate 12 and the second substrate 14.

The first substrate 12 is the front substrate of the liquid crystal panel assembly 10, and the second substrate 14 is the rear substrate of the liquid crystal panel assembly 10. On the outer surface of the first substrate 12 and the second substrate 14, a pair of polarizing plates 24, 26 whose polarization axes are perpendicular to each other are positioned. The inner surface of the first substrate 12 on which the common electrode 18 is located and the inner surface of the second substrate 14 on which the pixel electrodes 20 and the switching elements 22 are positioned are covered with the alignment layer 28. .

A plurality of gate lines 30 transmitting a gate signal and a plurality of data lines 32 transmitting a data signal are formed on an inner surface of the second substrate 14. The gate lines 30 are located next to each other along the row direction, and the data lines 32 are located next to each other along the column direction.

One pixel electrode 20 is positioned for each sub-pixel, and each sub-pixel includes a switching element 22 connected to the gate line 30 and a data line 32, and a liquid crystal connected to the switching element 22. Capacitor Clc (not shown) and sustain capacitor Cst (not shown) are formed. Holding capacitor Cst can be omitted as needed.

The switching element 22 may be formed of a thin film transistor, the control terminal and the input terminal of which are connected to the gate line 30 and the data line 32, respectively, and the output terminal of which is connected to the liquid crystal capacitor Clc.

The color filter 34 is disposed between the first substrate 12 and the common electrode 18. The color filter 34 is composed of red, green, and blue filters corresponding to one sub-pixel, and three sub-pixels in which three filters of red, green, and blue are located constitute one pixel.

When the thin film transistor, which is the switching element 22, is turned on in the liquid crystal panel assembly 10 having the above-described configuration, an electric field is formed between the pixel electrode 20 and the common electrode 18. The twist angle of the liquid crystal molecules positioned in the liquid crystal layer 16 is changed by this electric field to control a light transmission amount for each sub-pixel, thereby implementing a predetermined color image.

3 is a partial cutaway perspective view of the backlight unit according to the first embodiment, and FIG. 4 is a partial cross-sectional view of the fourth substrate and the electron emission unit illustrated in FIG. 3.

Referring to the drawings, the backlight unit 40 includes a third substrate 42 and a fourth substrate 44 which are disposed to face each other at a predetermined interval. The sealing member 46 is disposed at the edge of the third substrate 42 and the fourth substrate 44 to bond the two substrates, and the internal space is evacuated with a vacuum of approximately 10-6 Torr, so that the third substrate 42 The fourth substrate 44 and the sealing member 46 constitute a vacuum container.

The third substrate 42 becomes the front substrate of the backlight unit 40 facing the liquid crystal panel assembly, and the fourth substrate 44 becomes the rear substrate of the backlight unit 40. One surface of the fourth substrate 44 facing the third substrate 42 is provided with an electron emission unit 48 for electron emission, and one surface of the third substrate 42 facing the fourth substrate 44 is a light emitting unit. 50 is provided.

First, the electron emission unit 48 will be described. The electron emission unit 48 may include the cathode electrodes 52 formed in a stripe pattern along one direction of the fourth substrate 44 and the insulating layer 54. The gate electrodes 56 are formed in a stripe pattern along a direction orthogonal to the cathode electrode 52, and the electron emission units 58 electrically connected to the cathode electrode 52.

The gate electrodes 56 may be disposed side by side in the row direction of the fourth substrate 44, and may function as scan electrodes by receiving a scan driving voltage. The cathode electrodes 52 may be arranged side by side in the column direction of the fourth substrate 44, and may function as a data electrode by receiving a data driving voltage.

Electron emitters 58 are formed in the cathode electrode 52 at each intersection of the cathode electrode 52 and the gate electrode 56. Openings 541 and 561 corresponding to the electron emission portions 58 are formed in the insulating layer 54 and the gate electrodes 56 so that the electron emission portions 58 are exposed on the fourth substrate 44. do. In this embodiment, the intersection area of the cathode electrode 52 and the gate electrode 56 corresponds to one pixel area of the backlight unit 40.

The electron emission unit 58 is made of materials that emit electrons when an electric field is applied in a vacuum, such as a carbon-based material or a nanometer (nm) size material. The electron emission unit 58 may include, for example, carbon nanotubes, graphite, graphite nanofibers, diamonds, diamond-like carbons, C60, silicon nanowires, or a combination thereof, and may be screen printed or directly grown. , Chemical vapor deposition or sputtering, and the like.

On the other hand, the electron emission portion may be formed of a tip structure having a pointed tip mainly made of molybdenum (Mo) or silicon (Si).

Next, the light emitting unit 50 provided on the third substrate 42 includes a fluorescent layer 60 and an anode electrode 62 positioned on one surface of the fluorescent layer 60. The fluorescent layer 60 may be formed of a white fluorescent layer or a combination of red, green, and blue fluorescent layers. In the figure, the first case is illustrated.

The white fluorescent layer may be formed on the entirety of the third substrate 42 or may be divided and positioned in a predetermined pattern so that one white fluorescent layer is positioned in each pixel area. The red, green, and blue fluorescent layers may be divided and positioned in a predetermined pattern in one pixel area.

The anode electrode 62 may be formed of a metal film such as aluminum (Al) covering the surface of the fluorescent layer 60. The anode electrode 62 is an acceleration electrode for attracting an electron beam, and is applied with a high voltage (a positive DC voltage of approximately several thousand volts) to maintain the fluorescent layer 60 in a high potential state, and the visible light emitted from the fluorescent layer 60 The visible light emitted toward the fourth substrate 44 is reflected toward the third substrate 42 to increase the brightness of the screen.

In the above-described configuration, the FEA type electron emission device includes a cathode electrode 52, a gate electrode 56, electron emission portions 58, and a corresponding fluorescent layer 60 constituting one pixel.

In the above configuration, when a predetermined driving voltage is applied to the cathode electrodes 52 and the gate electrodes 56, an electric field is formed around the electron emission section 58 in the pixel region in which the voltage difference between the two electrodes is greater than or equal to the threshold. Electrons are emitted. The emitted electrons are attracted by the high voltage applied to the anode electrode 62 and collide with the corresponding fluorescent layer 60 to emit light. The emission intensity of the pixel-specific fluorescent layer 60 corresponds to the electron beam emission amount of the pixel.

5 is a partial plan view of the electron emission unit 48 'of the backlight unit according to the second embodiment.

Referring to the drawings, in this embodiment, two or more intersection regions of the cathode electrode 52 'and the gate electrode 56' are combined to form one pixel region A. Referring to FIG. In this case, when two or more cathode electrodes 52 'and two or more gate electrodes 56' are combined to form one pixel region A, the two or more cathode electrodes 52 'are formed. It is electrically connected to each other to receive the same driving voltage, and two or more gate electrodes 56 'are also electrically connected to each other to receive the same driving voltage.

To this end, the two or more cathode electrodes 52 ′ and the two or more gate electrodes 56 ′ extend to the edge of the fourth substrate to form a connection member such as a flexible printed circuit board (FPCB). Ends (not shown) may be connected to each other.

In the drawing, as an example, nine crossing regions where three cathode electrodes 52 'and three gate electrodes 56' intersect form one pixel region A is illustrated.

In both the back light unit of the first embodiment and the back light unit of the second embodiment, the compression force applied to the vacuum container is supported between the third substrate 42 and the fourth substrate 44 and the distance between the two substrates is maintained. Spacers 64 (see Fig. 4) are arranged to keep the constant. The spacers 64 are preferably located outside the pixel area, not in the center of the pixel area.

In addition, if necessary, the third substrate 42 itself, which is a front substrate, may have a light diffusing function to function as a diffusion plate, and as shown in FIG. 6, a third substrate facing the liquid crystal panel assembly ( A diffusion plate 66 having a light diffusing function may be disposed on an outer surface of the 42.

As described above, the liquid crystal display device 100 of the first to third embodiments of the present invention uses a kind of low resolution display panel having a smaller number of pixels than the liquid crystal panel assembly 10 as the backlight unit. The backlight unit is driven through a passive matrix method using scan electrodes and data electrodes, and provides light of different intensities to the pixels of the liquid crystal panel assembly 10 corresponding to each pixel.

The following table tests the display quality, the manufacturing cost of the driving circuit portion, the ease of manufacture, etc. while changing the number of pixels of the backlight unit for the liquid crystal panel assembly 10 having an arbitrary resolution, and the liquid crystal panel derived according to the result. The optimal number of pixels of the backlight unit for each resolution of the assembly 10 is shown.

Based on the above results, it can be seen that (liquid crystal panel assembly pixel number) / (backlight unit pixel number) is preferably in the range of 240 to 5,852. If the value exceeds 5,852, the effect of improving the dynamic contrast ratio by the backlight unit is insufficient, and if the value is less than 240, the manufacturing and driving of the backlight unit becomes difficult, thereby increasing the manufacturing cost.

Further, in the first to third embodiments of the present invention, one pixel of the backlight unit may be formed to have a size of 2 to 50 mm along the row direction and / or the column direction. If the pixel size in the row direction and / or column direction is less than 2 mm, the backlight unit 40 has a considerable number of pixels, which makes it difficult to process the circuit signal, and the pixel size in the row direction and / or column direction If it exceeds 50mm, the backlight unit may have a small number of pixels, and the image quality improvement effect of the backlight unit may be insufficient.

As described above, the liquid crystal display device 100 according to the present embodiment uses a backlight unit having the above-described configuration, and thus, a conventional cold cathode fluorescent lamp (hereinafter referred to as CCFL) and a light emitting diode (hereinafter referred to as LED). Compared with the backlight unit of the type has the following advantages.

Since the backlight units of the first to third embodiments of the present invention are surface light sources, a plurality of optical members used for the CCFL type backlight unit and the LED type backlight unit are not required. Therefore, in the backlight unit of the present embodiment, almost no light loss occurs while passing through the optical member, and the light unit does not have to emit light of excessive intensity in consideration of the light loss, thereby achieving excellent efficiency with low power consumption.

In addition, the backlight units of the first to third embodiments of the present invention are basically lower power consumption than the CCFL type backlight unit, and can reduce the cost by not using the optical member, the LED type back Lower manufacturing costs than light units. In addition, the backlight unit of the present embodiment can be easily applied to a large liquid crystal display device of 30 inches or more because it is easy to enlarge the size.

Hereinafter, a light emitting device using the display device according to the third exemplary embodiment of the present invention, a display device using the same, a method of driving the light emitting device, and a method of driving the display device will be described in detail.

7 is a block diagram illustrating a display device according to a third exemplary embodiment of the present invention. The display device according to the third exemplary embodiment of the present invention is a light receiving element and includes a liquid crystal panel assembly using the liquid crystal element. However, the present invention is not limited thereto.

As shown in FIG. 7, the display device according to the third exemplary embodiment of the present invention includes a liquid crystal panel assembly 10, a gate driver 102 and a data driver 104 connected to the liquid crystal panel assembly 10, and data. The gray voltage generator 106 connected to the driver 104, the backlight unit 40 ′, and a signal controller 108 controlling them are included.

The liquid crystal panel assembly 10 includes a plurality of signal lines G1 -Gn and D1-Dm as viewed in an equivalent circuit, and a plurality of pixels PX connected to the signal lines and arranged in a substantially matrix form. do. The signal lines G1 -Gn and D1 -Dm include a plurality of gate lines G1 -Gn for transmitting a gate signal and a plurality of data lines D1 -Dm for transmitting a data signal.

Connected to each pixel PX, for example, the i-th (i = 1,2, ... n) gate line Gi and the j-th (j = 1,2, ... m) data line Dj The pixel 11 includes a switching element Q connected to signal lines Gi and Dj, a liquid crystal capacitor Clc, and a storage capacitor Cst connected thereto. Holding capacitor Cst can be omitted as needed.

The switching element Q is a three-terminal element such as a thin film transistor provided on a lower substrate (not shown), the control terminal of which is connected to the gate line Gi, and the input terminal of which is connected to the data line Dj. The output terminal is connected to the liquid crystal capacitor Clc and the storage capacitor Cst.

The gray voltage generator 106 generates two sets of gray voltages (or a set of reference gray voltages) related to the transmittance of the pixel PX. One of the two sets has a positive value for the common voltage Vcom, and the other set has a negative value.

The gate driver 102 is connected to the gate lines G1 -Gn of the liquid crystal panel assembly 10 to receive a gate signal formed of a combination of the gate on voltage Von and the gate off voltage Voff. To apply.

The data driver 104 is connected to the data lines D1-Dm of the liquid crystal panel assembly 10, selects a gray voltage from the gray voltage generator 106, and uses the data driver 104 as a data signal to the data lines D1-Dm. Is authorized. However, when the gray voltage generator 106 provides only a predetermined number of reference gray voltages instead of providing all of the voltages for all grays, the data driver 104 divides the reference gray voltages and thus the gray voltages for all grays. Generate and select the data signal from it.

The signal controller 108 controls the gate driver 102, the data driver 104, the backlight unit controller 110, and the like. The signal controller 108 receives an input image signal R, G, B and an input control signal for controlling the display thereof from an external graphic controller (not shown).

The input image signals R, G, and B contain luminance information of each pixel PX, and luminance has a predetermined number, for example, 1024 (= 2 ¹⁰ ), 256 (= 2 ⁸ ), or 64 ( = 2 ⁶ ) Gray scale. Examples of the input control signal include a vertical sync signal Vsync, a horizontal sync signal Hsync, a main clock MCLK, and a data enable signal DE.

The signal controller 108 appropriately processes the input image signals R, G, and B based on the input image signals R, G, and B and the input control signals according to the operating conditions of the liquid crystal panel assembly 10, and controls the gate. After generating the signal CONT1 and the data control signal CONT2, the gate control signal CONT1 is sent to the gate driver 102, and the data control signal CONT2 and the processed image signal DATA are transferred to the data driver 104). In addition, the signal controller 108 transmits the gate control signal CONT1, the data control signal CONT2, and the processed image signal DATA to the backlight unit controller 110.

The backlight unit 40 ′ includes a backlight unit controller 110, a column driver 112, a scan driver 114, and a display unit 116.

The backlight unit controller 110 generates the emission signal CLS using the image signals DATA of the plurality of liquid crystal pixels PX corresponding to one pixel EPX of the backlight unit, and the column driver 112. To pass). In detail, the backlight unit controller 110 detects the highest gray level among the plurality of pixels PX corresponding to one pixel EPX of the backlight unit, and includes a plurality of backlight unit pixels corresponding to the detected gray level ( The tone of EPX) is determined. In addition, the backlight unit controller 110 converts the data into digital data and transmits the converted digital data to the column driver 112, and the digital data is included in the emission signal CLS. In addition, the backlight unit controller 110 generates a scan driving control signal CS using the gate control signal CONT1, and transmits the scan driving control signal CS to the scan driver 114. The backlight unit controller 110 generates the emission control signal CC using the data control signal CONT2 and transmits the emission control signal CC to the column driver 112.

The display unit 116 includes a plurality of scan lines S1 -Sp for transmitting a scan on signal, a plurality of column lines C1-Cq for transmitting a column signal, and a plurality of light emitting pixels EPX. Each of the plurality of light emitting pixels EPX is positioned in a region defined by the scan lines S1 -Sp and the column lines C1 -Cq intersecting the scan lines. The scan lines S1-Sp are connected to the scan driver 114, and the column lines C1 -Cq are connected to the column driver 112. The scan driver 114 and the column driver 112 are connected to the backlight unit controller 110 to operate according to the control signal of the backlight unit controller 110.

The scan driver 114 is connected to the plurality of scan lines S1 -Sp, and each backlight unit pixel EPX is connected to the plurality of liquid crystal pixels EX corresponding to the scan unit control signal CS. A plurality of scan on signals are generated so as to emit light synchronously, and are transmitted to the scan lines S1-Sp. At this time, the scan on signal is maintained at the first level for the first period. In addition, the scan driver 114 generates a scan reset signal having a second level and transmits the scan reset signal to the scan lines S1-Sp during the second period. The scan driver 114 according to the embodiment of the present invention sequentially transmits a scan on signal and a scan reset signal to the gate electrode. For convenience of explanation, the scan on signal and the scan reset signal sequentially transmitted are designated as the first scan signal.

The column driver 112 is connected to a plurality of column lines C1-Cq, and each backlight unit pixel EPX corresponds to a plurality of liquid crystals according to the emission control signal CC and the emission signal CLS. Control to emit light corresponding to the gray scale of the pixel EX. The column driver 112 generates a plurality of emission data on signals according to the emission signal CLS and transmits the plurality of emission data on signals to the plurality of column lines C1 to Cq according to the emission control signal CC. That is, the light emitting pixel EPX is synchronized to emit light with a predetermined gray scale in accordance with the display of the image on the plurality of liquid crystal pixels EX corresponding to one backlight unit pixel EPX. At this time, the light emission data on signal is maintained at the third level for the first period. The column driver 112 generates a light emission reset signal having a fourth level and transmits the light emission reset signal to the column lines C1-Cq during the second period. The column driver 112 according to an exemplary embodiment of the present invention sequentially transmits the light emission data on signal and the light emission reset signal to the cathode electrode. For convenience of description, the emission data on signal and the emission reset signal sequentially transmitted are designated as the first emission data signal.

Hereinafter, a first scan signal including a scan reset signal and a first emission data signal including a light emission reset signal will be described with reference to FIGS. 8 and 9. The signal according to the third embodiment of the present invention may have a positive voltage level or a negative voltage level, and includes a reference level that may be a reference for expressing a relative magnitude of the voltage. In this case, the reference level may be a positive voltage or a negative voltage, and may have a different value according to a user's setting.

8A and 8B are waveforms illustrating a scan on signal s [i] and a first scan signal s` [i] according to a third embodiment of the present invention. FIG. 8A illustrates the scan on signal s [i] transmitted to the scan lines S1-Sp, and FIG. 8B illustrates the first scan signal s that applies the scan reset signal to the scan on signal s [i]. `[i]). The scan reset signal according to the third embodiment of the present invention has a polarity opposite to that of the scan on signal s [i] and has the same polarity as the charge formed by the scan on signal s [i].

As shown in FIG. 8A, the scan-on signal s [i] according to the third embodiment of the present invention uses a square pulse. At this time, the waveform of the scan-on signal s [i] is increased from the reference level to the first level during the first period T11 by the time constant determined by the resistor and the capacitor and is maintained at the first level for the predetermined period. do. Then, during the second period T12, it gradually decreases from the first level to become the reference level. Therefore, the scan-on signal s [i] has a slow response time according to the time constant, and the light emission data applied to the column lines C1-Cq during the second period T12 gradually decreasing at the first level. A voltage difference with the on signal c [i] may occur to cause unnecessary electron emission.

In order to prevent such a phenomenon, the first scan signal s` [i] shown in FIG. 8B according to the third embodiment of the present invention includes the scan on signal s [i] and the scan reset signal. . The first scan signal s` [i] increases from the reference level to the first level during the first period T11 and remains at the first level for a predetermined time, similarly to the scan on signal s [i]. . Further, the first scan signal s` [i] has a scan reset signal of a second level having a polarity opposite to the first level during the third period T13. In this case, in the third period T13 in which the first scan signal s` [i] is increased from the second level to the reference level, the third period T13 decreases the scan on signal s [i] from the first level to the reference level. Since it is shorter than the two periods T12, it can have a fast response speed corresponding thereto. Therefore, a fast response speed can be obtained by using the first scan signal s' [i] including the scan reset signal.

In addition, the first scan signal includes a scan reset signal having the same polarity as the charge formed on the wall of the metal to which the scan on signal s [i] is applied, thereby reducing the charge charged on the metal wall. have. For example, when the voltage difference between the scan on signal and the light emitting data on signal occurs and electrons are emitted, if the scan on signal s [i] is a first level having a positive voltage, the scan on signal s [i ]) Around the metal wall is negatively charged. At this time, when the scan reset signal is applied at a second level having a negative voltage, negative charges formed around the metal wall and negative charges charged to the wall due to the applied negative voltage are reduced. Therefore, by applying the first scan signal s` [i] including the scan reset signal, it is possible to reduce the charge charged on the wall, thereby preventing unnecessary electron emission, thereby reducing power consumption. Can be lowered.

9A and 9B are waveforms showing the light emission data on signal c [i] and the first light emission data on signal c` [i] according to the third embodiment of the present invention. FIG. 9A shows the light emission data on signal c [i] transmitted to the column lines C1 to Cq, and FIG. 9B shows first light emission data applying the light emission reset signal to the light emission data on signal c [i]. Signal c` [i]. The light emission reset signal according to the third embodiment of the present invention has a polarity opposite to that of the light emission data on signal c [i] and has the same polarity as the charge formed by the light emission data on signal c [i]. .

As shown in Fig. 9A, the light emission data on signal c [i] according to the third embodiment of the present invention uses a square pulse. At this time, the waveform of the light emitting data on signal c [i] decreases from the reference level to the third level during the first period T21 by the time constant determined by the resistor and the capacitor to the third level during the predetermined period. maintain. Then, the second level T22 gradually increases from the third level to become the reference level. Accordingly, the emission data on signal c [i] has a slow response time according to the time constant, and the scan applied to the scan lines S1-Sp during the second period T22 gradually increasing at the third level. A voltage difference with the on signal s [i] may occur to cause unnecessary electron emission.

In order to prevent such a phenomenon, the first light emission data signal c` [i] shown in FIG. 9B according to the third embodiment of the present invention is configured to generate the light emission data on signal c [i] and the light emission reset signal. Include. The first emission data signal c` [i] decreases from the reference level to the third level during the first period T21 in the same manner as the emission data on signal c [i] and returns to the third level for a predetermined time. maintain. In addition, the first light emission data signal c ′ [i] has a fourth level light emission reset signal having a polarity opposite to the third level during the third period T23. At this time, in the third period T23 in which the first emission data signal c` [i] is decreased from the fourth level to the reference level, the emission data on signal c [i] is increased from the third level to the reference level. Since it is shorter than the second period T12, it may have a fast response speed. Accordingly, a fast response speed can be obtained by using the first emission data signal c ′ [i] including the emission reset signal.

In addition, the first light emission data signal c` [i] includes a light emission reset signal having the same polarity as the charge formed on the wall of the metal to which the light emission data on signal is applied, thereby receiving charge charged on the metal wall. Can be reduced. For example, when the voltage difference between the scan on signal and the light emitting data on signal is generated and electrons are emitted, the light emitting data on signal is applied when the light emitting data on signal c [i] is a third level having a negative voltage. Positive charges are formed around the metal wall. At this time, when the light emission reset signal is applied at the fourth level having the positive voltage, the positive charges formed on the periphery of the metal wall and the positive charge charged on the wall due to the applied positive voltage are reduced. Therefore, by applying the first light emission data signal c` [i] including the light emission reset signal, it is possible to reduce the charge charged on the wall, thereby preventing unnecessary electron emission, and thus power consumption. Can be lowered.

The backlight unit 40 'according to the third embodiment of the present invention emits light by the voltage difference between the first scan signal s` [i] and the first light emission data signal c` [i]. Then, by using the first scan signal s` [i] and the first light emission data signal c` [i], the scan on signal s [i] and the light emission data on signal c [i] Fast response speed can be obtained, and thus the distortion of the signal can be prevented. Further, by using the scan reset signal and the light emission reset signal, the charges charged on the wall to which the scan on signal s [i] and the light emission data on signal c [i] are applied are reduced, thereby unnecessary electron emission. Can be prevented and thus power consumption and temperature rise can be prevented.

The embodiment using a display device using a liquid crystal panel assembly has been described so far, but the present invention is not limited thereto. As a display device other than self-luminous, it is applicable to both display devices that receive images from a backlight unit and display an image.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to the range of.

The light emitting device, the display device using the same, a method of driving the light emitting device, and a method of driving the display device according to the features of the present invention can obtain a faster response speed by using a scan reset signal and a light emission reset signal, and thus signal distortion phenomenon Can be prevented. In addition, unnecessary electron emission can be prevented, and thus power consumption and temperature rise can be prevented.

Claims (20)

A panel assembly including a plurality of gate lines for transmitting a plurality of gate signals, a plurality of data lines for transmitting a plurality of data signals, and a plurality of pixels defined by the plurality of gate lines and the plurality of data lines, and A plurality of scan lines for transmitting a plurality of first scan signals, a plurality of column lines for transmitting a plurality of first light emitting data signals, and a plurality of first backlights defined by the plurality of scan lines and the plurality of column lines. A backlight unit having unit pixels, The first scan signal includes a scan reset signal. The method of claim 1, The first backlight unit pixel corresponds to a plurality of pixels of the panel assembly, and emits light at a luminance corresponding to the highest gray level among the plurality of pixels. The method of claim 2, The first scan signal, And a scan reset signal having a first level during a first period and a scan reset signal having a second level during a second period, wherein polarities of the first level and the second level are different from each other. The method of claim 3, The scan reset signal, A display device having the same polarity as the charge formed by the first level scan on signal. The method of claim 4, wherein And the plurality of first backlight unit pixels are electron emission elements that emit light by a voltage difference between the plurality of first scan signals and the plurality of first emission data signals. A panel assembly including a plurality of gate lines for transmitting a plurality of gate signals, a plurality of data lines for transmitting a plurality of data signals, and a plurality of pixels defined by the plurality of gate lines and the plurality of data lines, and A plurality of scan lines for transmitting a plurality of first scan signals, a plurality of column lines for transmitting a plurality of first light emitting data signals, and a plurality of first backlights defined by the plurality of scan lines and the plurality of column lines. A backlight unit having unit pixels, The first light emitting data signal includes a light emitting reset signal. The method of claim 6, The first backlight unit pixel corresponds to a plurality of pixels of the panel assembly, and emits light at a luminance corresponding to the highest gray level among the plurality of pixels. The method of claim 7, wherein The first light emission data signal, And a light emission reset signal having a first level during a first period and a light emission reset signal having a second level during a second period, wherein the polarities of the first level and the second level are different from each other. The method of claim 8, The light emission reset signal, A display device having the same polarity as the charge formed by the light emission data on signal of the first level. The method of claim 9, And the plurality of first backlight unit pixels are electron emission elements that emit light by a voltage difference between the plurality of first scan signals and the plurality of first emission data signals. A plurality of scan lines for transmitting a plurality of first scan signals, a plurality of column lines for transmitting a plurality of first light emitting data signals, and a plurality of backlight units defined by the plurality of scan lines and the plurality of column lines. A backlight unit having pixels; The first scan signal includes a scan reset signal, and the first light emitting data signal includes a light emission reset signal. The method of claim 11, The first scan signal, And a scan reset signal having a first level during a first period, and a scan reset signal having a second level during a second period, wherein polarities of the first level and the second level are different from each other. The method of claim 12, The scan reset signal, A light emitting device having the same polarity as the charge formed by the first level of scan on signal. The method of claim 11, The first light emission data signal, And a light emission data on signal having a third level during the first period, and a light emission reset signal having a fourth level during the second period, wherein the polarities of the third level and the fourth level are different from each other. The method of claim 14, The light emission reset signal, And a light emitting device having the same polarity as the charge formed by the third level of light emitting data on signal. A method of driving a display device comprising a panel assembly for displaying an image, and a backlight unit for supplying a backlight to the panel assembly and including a plurality of scan lines and a plurality of column lines. (a) transferring a scan on signal to a first scan line of the plurality of scan lines, (b) synchronizing with the scan on signal, transferring a light emitting data on signal to a first column line, and and (c) transferring a scan reset signal to the first scan line and a light emission reset signal to the first column line. The method of claim 16, The panel assembly includes a plurality of pixels, the backlight unit includes a plurality of backlight unit pixels, The first backlight unit pixel of the plurality of backlight unit pixels corresponds to a plurality of pixels of the panel assembly, and emits light at a luminance corresponding to the highest gray level among the plurality of pixels. The method of claim 17, Step c) is The scan on signal having a first level during a first period, and the scan reset signal having a second level during a second period, wherein the polarities of the first level and the second level are different from each other, A light emission data on signal having a third level during a first period, and a light emission reset signal having a fourth level during a second period, wherein polarities of the third level and the fourth level are different from each other; Driving method. (a) delivering a scan on signal to a first scan line of the plurality of scan lines, (b) synchronizing with the scan on signal, transferring a light emitting data on signal to a first column line, and (c) transmitting a scan reset signal to the first scan line, and transmitting a light emission reset signal to the first column line. The method of claim 19, Step c) is The scan on signal having a first level during a first period, and the scan reset signal having a second level during a second period, wherein the polarities of the first level and the second level are different from each other, The light emitting data on signal having a third level during a first period, and the light emitting reset signal having a fourth level during a second period, wherein the polarities of the third level and the fourth level are different from each other. Driving method.

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