KR20050053885A - Four color liquid crystal display - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-color liquid crystal display device, and more particularly, to a liquid crystal display device capable of improving color reproducibility by expanding color coordinates. The liquid crystal display according to the exemplary embodiment of the present invention includes a plurality of pixels arranged in a matrix form, and each of the plurality of pixels includes a first subpixel group and a second subpixel group. The first subpixel group includes a first three primary color subpixel, the second subpixel group includes one of a second three primary color subpixels, and the first three primary colors and the second three primary colors have a complementary color relationship. The first subpixel group and the second subpixel group are adjacent to each other. In this way, four-color subpixels in which one of the cyan, yellow, and magenta subpixels are added in addition to the red, green, and blue subpixels are used to express colors in pixel units, thereby increasing the range in which colors can be reproduced. .

Description

4 color liquid crystal display {FOUR COLOR LIQUID CRYSTAL DISPLAY}

The present invention relates to a four-color liquid crystal display device.

A general liquid crystal display device includes two display panels and a liquid crystal layer having dielectric anisotropy interposed therebetween. An electric field is applied to the liquid crystal layer, and the intensity of the electric field is adjusted to adjust the transmittance of light passing through the liquid crystal layer to obtain a desired image. Such liquid crystal displays are typical among portable flat panel displays (FPDs) that are easy to carry. Among them, TFT-LCDs using thin film transistors (TFTs) as switching elements are mainly used.

On the other hand, as the liquid crystal display device becomes larger, its area is gradually being expanded not only as a computer monitor but also as a display device such as a television.

In this trend, LCDs suffer from color reproducibility.

Color reproducibility refers to reproducing almost the same color when present in nature. Currently, an LCD displays an image using a subpixel including a color filter of red (R), blue (B), and green (G) as a primary color as one pixel unit.

The current broadcast standard expresses only the colors defined by the standards of the NTSC (national television system committee) and the European Broadcasting Union (EBU). That is, the color coordinates represent only the colors in the triangular area defined by the NTSC standard. However, the NTSC standard expresses about 90% of actual natural colors, and the remaining 10% is distorted.

Moreover, since LCD can express only about 70% of the NTSC-standard color reproduction range, there are more natural colors that cannot be expressed.

Therefore, the technical problem to be achieved by the present invention is to provide a four-color liquid crystal display device that can broaden the color reproduction range.

According to an exemplary embodiment of the present invention, a liquid crystal display includes a plurality of pixels arranged in a matrix form.

Each of the plurality of pixels includes a first subpixel group and a second subpixel group.

The first subpixel group includes a first three primary color subpixel, the second subpixel group includes one of a second three primary color subpixel,

The first three primary colors and the second three primary colors have a complementary color relationship,

The first subpixel group and the second subpixel group are adjacent to each other.

Preferably, the subpixels in the one pixel are arranged in a 2x2 matrix.

The first primary color subpixel may include red, blue, and green subpixels, and the second primary color subpixel may include cyan, magenta, and yellow subpixels.

The subpixels in the one pixel may include the red and blue subpixels in a row direction and may include red and green subpixels in a column direction.

DETAILED DESCRIPTION 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.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like parts are designated by like reference numerals throughout the specification. When a part of a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the other part being "right over" but also another part in the middle. On the contrary, when a part is "just above" another part, there is no other part in the middle.

A liquid crystal display according to an exemplary embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

1 is a block diagram of a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 2 is an equivalent circuit diagram of one subpixel of the liquid crystal display according to an exemplary embodiment of the present invention.

As shown in FIG. 1, a liquid crystal display according to an exemplary embodiment of the present invention includes a liquid crystal panel assembly 300, a gate driver 400, a data driver 500, and a data driver The gray voltage generator 800 connected to the signal generator 500 and a signal controller 600 for controlling the gray voltage generator 800 are included.

The liquid crystal panel assembly 300 includes a plurality of display signal lines G ₁ -G _n , D ₁ -D _m , and a plurality of sub-pixels connected to the plurality of display signal lines G ₁ -G _n and D ₁ -D _m in an equivalent circuit.

The display signal lines G ₁ -G _n and D ₁ -D _m are a plurality of gate lines G ₁ -G _n for transmitting a gate signal (also called a “scan signal”) and a data signal line or data for transmitting a data signal. Line D ₁ -D _m . The gate lines G ₁ -G _n extend substantially in the row direction and are substantially parallel to each other, and the data lines D ₁ -D _m extend substantially in the column direction and are substantially parallel to each other.

Each subpixel includes a switching element Q connected to a display signal line G ₁ -G _n , D ₁ -D _m , a liquid crystal capacitor C _LC , and a storage capacitor C _ST connected thereto. ). The holding capacitor C _ST can be omitted as necessary.

The switching element Q is provided on the lower panel 100, and the control terminal and the input terminal are connected to the gate line G ₁ -G _n and the data line D ₁ -D _m, respectively. The output terminal is connected to the liquid crystal capacitor C _LC and the storage capacitor C _ST .

The liquid crystal capacitor C _LC has two terminals, the pixel electrode 190 of the lower panel 100 and the common electrode 270 of the upper panel 200, and the liquid crystal layer 3 between the two electrodes 190 and 270. It functions as a dielectric. The pixel electrode 190 is connected to the switching element Q, and the common electrode 270 is formed on the front surface of the upper panel 200 and receives a common voltage V _com . Unlike in FIG. 2, the common electrode 270 may be provided in the lower panel 100. In this case, both electrodes 190 and 270 may be linear or rod-shaped.

The storage capacitor C _ST is formed by overlapping a separate signal line (not shown) and the pixel electrode 190 provided on the lower panel 100, and a predetermined voltage such as a common voltage V _com is applied to the separate signal line. Is approved. However, the storage capacitor C _ST may be formed such that the pixel electrode 190 overlaps the front end gate line directly above the insulator.

On the other hand, in order to implement color display, each subpixel should display color, which is red, green, blue, cyan, yellow, and magenta (region) corresponding to the pixel electrode 190. by providing a color filter 230 of one of the magenta.

In FIG. 2, the color filter 230 is formed in a corresponding region of the upper panel 200. Alternatively, the color filter 230 may be formed above or below the pixel electrode 190 of the lower panel 100.

The color of the color filter 230 may be any one of red, green, and blue, which are three primary colors of light, or one of cyan, magenta, and yellow, which are complementary to these three primary colors.

Below, each subpixel is referred to as a red subpixel, a green subpixel, a blue subpixel, a cyan subpixel, a magenta subpixel, and a yellow subpixel according to the color indicated by the subpixel, and reference numerals denote R, G, B, Use C, M and Y

A polarizer (not shown) for polarizing light is attached to an outer surface of at least one of the two display panels 100 and 200 of the liquid crystal panel assembly 300.

The gray voltage generator 800 generates two sets of gray voltages related to the transmittance of the pixel. One of the two sets has a positive value for the common voltage (V _com ) and the other set has a negative value.

The gate driver 400 is connected to the gate lines G ₁ -G _n of the liquid crystal panel assembly 300 to receive a gate signal formed by a combination of a gate on voltage V _on and a gate off voltage V _off from the outside. It is applied to the gate lines G ₁ -G _n .

The data driver 500 is connected to the data lines D ₁ -D _m of the liquid crystal panel assembly 300 to select the gray voltage from the gray voltage generator 800 and apply the gray voltage to the pixel as a data signal. It consists of a circuit.

The signal controller 600 generates control signals for controlling operations of the gate driver 400 and the data driver 500, and provides the corresponding control signals to the gate driver 400 and the data driver 500.

Next, the display operation of the liquid crystal display will be described in more detail.

The signal controller 600 inputs an input control signal for controlling the RGB image signals R, G, and B and their display from an external graphic controller (not shown), for example, a vertical sync signal V _sync and a horizontal sync signal. (H _sync ), a main clock (MCLK), a data enable signal (DE) is provided. The signal controller 600 generates a gate control signal CONT1 and a data control signal CONT2 based on the input control signal, and adjusts the image signals R, G, and B to match the operating conditions of the liquid crystal panel assembly 300. After appropriately processing the four-color image signal, the gate control signal CONT1 is sent to the gate driver 400, and the data control signal CONT2 and the processed image signals R ', G', B ', and C are data driver. Export to 500. In FIG. 1, as an example, the processed video signal is illustrated as red (R '), green (G'), blue (B '), and cyan (C), and includes a cyan subpixel in addition to the three primary colors. According to the arrangement of the subpixels, the input image signals R, G, and B may be processed into four color image signals including magenta (M) and yellow (Y), and then transferred to the data driver 500.

The gate control signal CONT1 includes a vertical synchronization start signal STV indicating the start of output of the gate on pulse (gate on voltage section), a gate clock signal CPV for controlling the output timing of the gate on pulse, and a gate on pulse. An output enable signal OE or the like that defines a width.

The data control signal CONT2 applies a corresponding data voltage to the horizontal synchronization start signal STH indicating the start of input of the image data R ', G', B ', and C and the data lines D ₁ -D _m . Load signal LOAD, an inverted signal (RVS) that inverts the polarity of the data voltage with respect to the common voltage (V _com ) (hereinafter referred to as " polarity of the data voltage, " And a data clock signal HCLK and the like.

The data driver 500 sequentially receives and shifts image data R ', G', B ', and C corresponding to one row of subpixels according to the data control signal CONT2 from the signal controller 600. Image data R ', G', B ', and C are selected by selecting a gray voltage corresponding to each of the image data R', G ', B', and C among the gray voltages from the gray voltage generator 800. Is converted into the corresponding data voltage and applied to the corresponding data lines D ₁ -D _m .

The gate driver 400 applies the gate-on voltage V _on to the gate lines G ₁ -G _n in response to the gate control signal CONT1 from the signal controller 600, thereby applying the gate lines G ₁ -G _n. When the switching element Q connected to the () is turned on, the data voltage applied to the data lines D ₁ -D _m is applied to the corresponding subpixel through the turned on switching element Q.

The difference between the data voltage applied to the subpixel and the common voltage V _com is shown as the charging voltage of the liquid crystal capacitor C _LC , that is, the pixel voltage. The liquid crystal molecules vary in arrangement depending on the magnitude of the pixel voltage. As a result, the polarization of light passing through the liquid crystal layer 3 changes. This change in polarization is represented by a change in the transmittance of light by the polarizer.

After one horizontal period (or “1H”) (one period of the horizontal sync signal H _sync , the data enable signal DE, and the gate clock CPV), the data driver 500 and the gate driver 400 are next. The same operation is repeated for the subpixels in the row. In this manner, the gate-on voltage V _on is sequentially applied to all the gate lines G ₁ -G _n during one frame to apply the data voltage to all the subpixels. At the end of one frame, the next frame starts and the state of the inversion signal RVS applied to the data driver 500 is controlled so that the polarity of the data voltage applied to each subpixel is opposite to that of the previous frame ("frame"reversal"). In this case, the polarity of the data voltage flowing through one data line may be changed (“column inversion”) or the polarity of the data voltage applied to one pixel row may be different according to the characteristics of the inversion signal RVS within one frame ( "Dot reversal")

Meanwhile, in one embodiment according to the present invention, in addition to the red, green, and blue subpixels (R, G, and B), one of the subpixels (C, M, and Y) of cyan, magenta, and yellow is a basic unit of an image, that is, The arrangement of the four subpixels forming one pixel will be described in detail with reference to the drawings.

For the sake of explanation, the characteristics of the color are first outlined.

Each color is determined by the dominant wavelength, and the brightness of the color is determined by the intensity at the dominant wavelength. In this regard, the order of luminance for each subpixel according to each color is the order of yellow, cyan, and green subpixels (Y, C, G), and the blue subpixel (B) has the lowest luminance, and the red and magenta subfields. The pixels G and M belong to the middle thereof.

3A to 3F illustrate spatial arrangement of subpixels of a liquid crystal display according to an exemplary embodiment of the present invention.

As shown in Figs. 3A to 3C, subpixels in one pixel are arranged in a 2x2 matrix, and a set of red and blue subpixels R and B are located in one row, and green subpixels G and cyan The set of subpixels of one of magenta, magenta, and yellow subpixels (C, M, Y) is located in two rows. FIG. 3A illustrates a case in which green and cyan subpixels G and C are arranged in two rows, and FIG. 3B illustrates a case in which green and magenta subpixels G and M are arranged. FIG. This is the case where G and Y) are disposed.

The arrangement of the subpixels shown in FIGS. 3A-3C is only possible for example, and all possible subpixel arrangements may be used using the four subpixels. In this case, in consideration of the complementary color relationship between red, green, and blue, and cyan, magenta, and yellow, it is more efficient to dispose neighboring subpixels in a diagonal direction and neighboring subpixels in up, down, left, and right directions.

As such, four colors of one of the three primary colors of red, green, and blue subpixels (R, G, and B) plus one of cyan, magenta, and yellow are added as one pixel. As a result, the color reproduction range can be extended by extending the color coordinates in the direction of a subpixel added rather than when represented by the RGB three primary colors.

In addition, if the TV is produced using such a multi primary color LCD (MPC LCD), the cost of the color filter manufacturing process increases, but the factor is not so large compared to the total price of the TV, and the added value increase effect of the MPC LCD TV is greater. Can be.

A detailed structure of a thin film transistor array panel of a liquid crystal display according to an exemplary embodiment of the present invention will now be described in detail with reference to FIGS. 4 and 5.

4 is a layout view of a thin film transistor array panel for a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 5 is a cross-sectional view of the thin film transistor array panel illustrated in FIG. 4 taken along a line V-V ′.

A plurality of gate lines 121 are formed on the insulating substrate 110 to transfer gate signals. The gate line 121 mainly extends in the horizontal direction, and a part of each gate line 121 forms a plurality of gate electrodes 124. In addition, the other part of each gate line protrudes downward to form a plurality of expansions 127.

The gate line 121 includes a conductive film made of a silver-based metal such as silver (Ag) or a silver alloy having a low resistivity, or an aluminum-based metal such as aluminum (Al) or an aluminum alloy, and other materials in addition to the conductive film. In particular, chromium (Cr), titanium (Ti), tantalum (Ta), molybdenum (Mo) and their alloys have good physical, chemical and electrical contact properties with indium tin oxide (ITO) or indium zinc oxide (IZO). : Molybdenum-tungsten (MoW) alloy]. It may have a multilayer structure including another conductive film. An example of the combination of the lower layer and the upper layer is chromium / aluminum-neodymium (Nd) alloy.

The side of the gate line 121 is inclined, and the inclination angle is in a range of about 30-80 ° with respect to the surface of the substrate 110.

A gate insulating layer 140 made of silicon nitride (SiNx) is formed on the gate line 121.

A plurality of island-like semiconductors 154 made of hydrogenated amorphous silicon (amorphous silicon is abbreviated a-Si) and the like are formed on the gate insulating layer 140 on the gate electrode 124.

The upper portion of the semiconductor 154 is paired with a plurality of island-like ohmic contacts 163 and 165 made of a material such as n ⁺ hydrogenated amorphous silicon doped with a high concentration of silicide or n-type impurities. Formed.

Sides of the semiconductor 154 and the ohmic contacts 163 and 165 are also inclined, and the inclination angle is 30-80 °.

The plurality of data lines 171, the plurality of drain electrodes 175, and the plurality of storage capacitors are disposed on the ohmic contacts 163 and 165 and the gate insulating layer 140, respectively. conductor 177 is formed.

The data line 171 mainly extends in the vertical direction to cross the gate line 121 and transmit a data voltage. A plurality of branches extending from the data line 171 toward the drain electrode 175 forms a source electrode 173. The pair of source electrode 173 and the drain electrode 175 are separated from each other and positioned opposite to the gate electrode 124. The gate electrode 124, the source electrode 173, and the drain electrode 175 form a thin film transistor (TFT) together with the semiconductor 154, and a channel of the thin film transistor is connected to the source electrode 173. It is formed in the semiconductor 154 between the drain electrode 175.

The storage capacitor conductor 177 overlaps the extension portion 127 of the gate line 121.

The data line 171, the drain electrode 175, and the conductor 177 for the storage capacitor are also silver-based metals such as silver (Ag) or silver alloys having low resistivity, and aluminum-based metals such as aluminum (Al) and aluminum alloys. In addition to these conductive films, chromium (Cr), titanium (Ti), which have good physical, chemical and electrical contact properties with other materials, in particular indium tin oxide (ITO) or indium zinc oxide (IZO), It may have a multilayer film structure including another conductive film made of tantalum (Ta), molybdenum (Mo) and alloys thereof (eg, molybdenum-tungsten (MoW) alloys). An example of the combination of the lower layer and the upper layer is chromium / aluminum-neodymium (Nd) alloy.

Side surfaces of the data line 121, the drain electrode 175, and the storage capacitor conductor 177 are also inclined, and the inclination angle is in a range of about 30-80 ° with respect to the surface of the substrate 110.

The ohmic contacts 163 and 165 exist only between the semiconductor 154 below and the data line 171 and the drain electrode 175 thereon, and serve to lower the contact resistance.

On the data line 171, the drain electrode 175, the conductive capacitor 177 for the storage capacitor, and the exposed semiconductor 154, an organic material having excellent planarization characteristics and photosensitivity, plasma chemical vapor deposition (plasma) A passivation layer 180 made of a low dielectric constant insulating material such as a-Si: C: O, a-Si: O: F formed by enhanced chemical vapor deposition (PECVD), or silicon nitride, which is an inorganic material, is formed. It is. Alternatively, the passivation layer 180 may be formed of a double layer of organic material and silicon nitride.

The passivation layer 180 includes a plurality of contact holes 185, 187, and 189 respectively exposing the drain electrode 175, the conductive capacitor 177 for the storage capacitor, and the end portion 179 of the data line 171. Formed.

A plurality of pixel electrodes 190 and a plurality of contact assistants 97 made of ITO or IZO are formed on the passivation layer 180.

The pixel electrode 190 is physically and electrically connected to the drain electrode 175 and the storage capacitor conductor 177 through the contact holes 185 and 187, respectively, to receive a data voltage from the drain electrode 175, and to connect the conductor. Transfer data voltage to 177.

Referring to FIG. 2 again, the pixel electrode 190 to which the data voltage is applied generates two electric fields by generating an electric field together with the common electrode 270 of the other display panel 200 to which the common voltage V _com is applied. Rearrange the liquid crystal molecules of the liquid crystal layer (3).

In addition, as described earlier, the pixel electrode 190 and common electrode 270 is a capacitor (C _LC) of the liquid crystal capacitor (C _LC to done to maintain the applied voltage even after the thin film transistor is turned off, enhancing the voltage holding ability ) And another capacitor connected in parallel with it is called the “storage electrode” (C _ST ). The storage capacitor C _ST is formed by the superposition of the pixel electrode 190 and the neighboring gate line 121 (hereinafter, referred to as a “previous gate line”), and the like. In order to increase the storage capacitance, the extension portion 127 extending the gate line 121 is provided to increase the overlap area, while the conductor 177 for the storage capacitor is connected to the pixel electrode 190 and overlaps the extension portion 127. ) Is placed under the protective film 180 to bring the distance between the two closer.

The pixel electrode 190 also overlaps the neighboring gate line 121 and the data line 171 to increase the aperture ratio, but may not overlap.

The contact auxiliary member 97 is connected to the end portion 179 of the data line through the contact hole 189. The contact assisting member 97 is not essential to serve to protect adhesiveness between the end portion 179 of the data line 171 and an external device and to protect them, and application thereof is optional.

According to another embodiment of the present invention, a transparent conductive polymer may be used as the material of the pixel electrode 190, and in the case of a reflective liquid crystal display, an opaque reflective metal may be used. In this case, the contact assistant member 97 may be made of a material different from the pixel electrode 190, in particular, ITO or IZO.

An alignment layer 11 is formed on the passivation layer 180 and the pixel electrode.

In this way, the four primary colors can be used to increase the color reproduction range and further increase the added value of the product.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

1 is a block diagram of a liquid crystal display according to an exemplary embodiment of the present invention.

2 is an equivalent circuit diagram of one subpixel of a liquid crystal display according to an exemplary embodiment of the present invention.

3A to 3F illustrate spatial arrangement of subpixels of a liquid crystal display according to an exemplary embodiment of the present invention.

4 is a layout view of a thin film transistor array panel for a liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 5 is a cross-sectional view of the thin film transistor array panel illustrated in FIG. 4 taken along the line VV ′.

Claims (4)

A liquid crystal display device comprising a plurality of pixels arranged in a matrix form. Each of the plurality of pixels includes a first subpixel group and a second subpixel group. The first subpixel group includes a first three primary color subpixel, the second subpixel group includes one of a second three primary color subpixel, The first three primary colors and the second three primary colors have a complementary color relationship, The first subpixel group and the second subpixel group are adjacent to each other. Liquid crystal display. In claim 1, And the sub-pixels in the one pixel are arranged in a 2x2 matrix. In claim 2, The first tri-primary sub-pixel includes red, blue, and green sub-pixels, and the second tri-primary sub-pixel includes cyan, magenta, and yellow sub-pixels. In claim 3, And the subpixels in the one pixel include the red and blue subpixels in a row direction and a red and green subpixels in a column direction.