KR20080068343A - Liquid crystal display and driving method thereof - Google Patents

Abstract

An LCD device and a driving method thereof are provided to enhance image quality by displaying images according to selective application of reflective and transmissive modes or variation of gamma values based on the state of backlight. An LCD(Liquid Crystal Display) device includes a semi-transmissive LCD panel(300), a common voltage generator, drivers(400,500), a gray voltage generator(800), a signal controller(600), and a micro processor unit. The semi-transmissive LCD panel includes an optic sensor. The common voltage generator generates a common voltage to be applied to the semi-transmissive LCD panel. The drivers generate voltages which are applied to the semi-transmissive LCD panel. The gray voltage generator generates gray scale voltages for applying the drivers. The signal controller controls the drivers and the gray voltage generator. The micro processor unit applies control signals to the signal controller. The micro processor unit receives an output of the optic sensor, determines the illuminance of the outside, and changes the display characteristic of the semi-transmissive LCD panel according to the determination result.

Description

Liquid crystal display and its driving method {LIQUID CRYSTAL DISPLAY AND DRIVING METHOD THEREOF}

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 pixel of a liquid crystal display according to an exemplary embodiment of the present invention.

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

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

5 is an example of layout view of a liquid crystal display according to an exemplary embodiment of the present invention.

6 and 7 are cross-sectional views of the liquid crystal display of FIG. 5 taken along lines VI-VI 'and VII-VII', respectively.

8 is a graph illustrating an output voltage of an optical sensor according to external illumination according to an exemplary embodiment of the present invention.

9 is a circuit diagram of converting an output current of an optical sensor according to an embodiment of the present invention into an output voltage value.

10 is a partial circuit diagram of a signal controller according to an embodiment of the present invention.

11 illustrates a signal input to an FPC according to an embodiment of the present invention.

12 is a schematic diagram illustrating a driving sequence of a liquid crystal display according to an exemplary embodiment of the present invention.

13 is a circuit diagram of a gray voltage generator of a liquid crystal display according to an exemplary embodiment of the present invention.

14 illustrates a common voltage generated according to an embodiment of the present invention.

The present invention relates to a liquid crystal display and a driving method thereof.

The liquid crystal display is one of the most widely used flat panel display devices. The liquid crystal display includes two display panels on which field generating electrodes, such as a pixel electrode and a common electrode, are formed, and a liquid crystal layer interposed therebetween. Is applied to generate an electric field in the liquid crystal layer, thereby determining the orientation of liquid crystal molecules in the liquid crystal layer and controlling the polarization of incident light to display an image.

Such a liquid crystal display includes a transmissive type for displaying an image while light emitted from a backlight of the liquid crystal display passes through a panel, a reflective type for displaying an image while reflecting light incident from the front of the liquid crystal display, and a transmissive type and a reflective type. All have a transflective type.

Although the transmissive type is bright but the external light is strong, the transmissive type is frequently used because the image is difficult to recognize. In this case, the image is displayed in a transmissive form in a dark place and the image is displayed in a reflective form in a bright outside. However, there is a disadvantage in that the display quality is deteriorated because the reflective and transmissive display characteristics are different from each other.

The technical problem to be achieved by the present invention is an invention for improving the image quality regardless of the illuminance or the state of the backlight in the transflective liquid crystal display device.

In order to solve this problem, in the present invention, the transflective liquid crystal display detects an external illuminance or a state of the backlight and displays images according to different settings.

Specifically, the method of driving the display device according to the embodiment of the present invention comprises the steps of measuring the external illuminance using an optical sensor formed in the liquid crystal display panel, the step of distinguishing the measured external illuminance using a comparison circuit, And transmitting the separated external illuminance to the microprocessor unit and transmitting the control signal of the liquid crystal display panel according to the external illuminance.

The control signal of the liquid crystal display panel may change the data voltage applied to the liquid crystal display panel.

The control signal of the liquid crystal display panel may change the common voltage applied to the liquid crystal display panel.

The step of classifying the measured external illuminance by using a comparison circuit may divide the external illuminance into two or four stages.

When the external illuminance is the brightest, it may be driven in a reflection mode, and when the external illuminance is the darkest, it may be driven in a transmissive mode.

A method of driving a display device according to an exemplary embodiment of the present invention may include transmitting a signal input to a light source of a backlight to a microprocessor unit, wherein the microprocessor determines the state of the backlight according to the signal input to the light source; The microprocessor may include transmitting a control signal of the liquid crystal display panel according to the state of the backlight.

When the state of the backlight is off, it may be driven in a reflective mode, and when the state of the backlight is on, it may be driven in a transmissive mode.

According to an exemplary embodiment of the present invention, a liquid crystal display includes a transflective liquid crystal display panel including an optical sensor, a common voltage generation unit generating a common voltage applied to the liquid crystal display panel, and a voltage applied to the liquid crystal display panel. A driver; a gray voltage generator for generating a gray voltage applied to the driver; a signal controller for controlling the driver and the gray voltage generator; and a microprocessor unit for applying a control signal to the signal controller; After receiving the output of the optical sensor to determine the external illuminance and changes the display characteristics of the liquid crystal display panel according to the determined illuminance.

The change in display characteristics of the liquid crystal display panel may change the gray voltage generated by the gray voltage generator.

Changing display characteristics of the liquid crystal display panel may change the common voltage generated by the common voltage generator.

The common voltage generator, the driver, the gray voltage generator, and the signal controller may be formed of one chip.

According to an exemplary embodiment of the present invention, a display device includes a transflective liquid crystal display panel, a backlight unit including a light source for providing light to the liquid crystal display panel, a common voltage generating unit generating a common voltage applied to the liquid crystal display panel, and A driver for generating a voltage applied to the liquid crystal display panel, a gray voltage generator for generating a gray voltage applied to the driver, a signal controller for controlling the driver and the gray voltage generator, and a micro for applying a control signal to the signal controller And a processor unit, wherein the backlight unit outputs data on the state of the light source, and the microprocessor unit receives data on the state of the light source to change display characteristics of the liquid crystal display panel according to the state of the light source. do.

Changing the display characteristics of the liquid crystal display panel may change the gray voltage generated by the gray voltage generator.

Changing display characteristics of the liquid crystal display panel may change the common voltage generated by the common voltage generator.

The common voltage generator, the driver, the gray voltage generator, and the signal controller may be formed of one chip.

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. 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, 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.

First, a liquid crystal display according to an exemplary embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2.

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 pixel 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 500 connected thereto. 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 signal lines G ₁ -G _n , D ₁ -D _m and a plurality of pixels PX connected to the plurality of signal lines G ₁ -G _n , D ₁ -D _m , and arranged in a substantially matrix form. Include. On the other hand, in the structure shown in FIG. 2, the liquid crystal panel assembly 300 includes lower and upper panels 100 and 200 facing each other and a liquid crystal layer 3 interposed therebetween.

The 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 plurality of data lines for transmitting a data signal ( 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 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 PX connected to includes a switching element Q connected to the signal lines Gi and Dj, 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 a three-terminal element of a thin film transistor or the like provided in the lower panel 100, the control terminal of which is connected to the gate line G _i , and the input terminal of which is connected to the data line D _j . 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 the common voltage Vcom. Unlike in FIG. 2, the common electrode 270 may be provided in the lower panel 100. In this case, at least one of the two electrodes 190 and 270 may be linear or rod-shaped.

The storage capacitor C _ST , which serves as an auxiliary part of the liquid crystal capacitor C _LC , is formed by overlapping a separate signal line (not shown) and the pixel electrode 190 provided on the lower panel 100 with an insulator interposed therebetween. A predetermined voltage such as the common voltage Vcom is applied to this separate signal line. 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 pixel PX uniquely displays one of the primary colors (spatial division) or each pixel PX alternately displays the primary colors over time (time division). The desired color is recognized by the spatial and temporal sum of these primary colors. Examples of the primary colors include three primary colors such as red, green, and blue. 2 illustrates that each pixel PX includes a color filter 230 representing one of the primary colors in an area of the upper panel 200 corresponding to the pixel electrode 190 as an example of spatial division. Unlike FIG. 2, the color filter 230 may be formed above or below the pixel electrode 190 of the lower panel 100.

At least one polarizer (not shown) for polarizing light is attached to an outer surface of the liquid crystal panel assembly 300.

Referring back to FIG. 1, the gray voltage generator 800 generates two gray voltage sets (or reference gray voltage sets) 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.

A gate driver 400, a gate line (G ₁ -G _n) and is connected to the gate turn-on voltage (Von), and a gate signal consisting of a combination of a gate-off voltage (Voff), a gate line (G ₁ of the liquid crystal panel assembly 300 -G _n ).

The data driver 500 is connected to the data lines D ₁ -D _m of the liquid crystal panel assembly 300 and selects a gray voltage from the gray voltage generator 800 and uses the data line D ₁ as a data signal. -D _m ). However, when the gray voltage generator 800 provides only a predetermined number of reference gray voltages instead of providing all of the voltages for all grays, the data driver 500 divides the reference gray voltages to divide the gray voltages for all grays. Generate and select the data signal from it.

The signal controller 600 controls the gate driver 400, the data driver 500, and the like.

Each of the driving devices 400, 500, 600, and 800 may be mounted directly on the liquid crystal panel assembly 300 in the form of at least one integrated circuit chip, or may be a flexible printed circuit film (not shown). It may be mounted on the liquid crystal panel assembly 300 in the form of a tape carrier package (TCP) or mounted on a separate printed circuit board (not shown). Alternatively, these driving devices 400, 500, 600, and 800 may be integrated in the liquid crystal panel assembly 300 together with the signal lines G ₁ -G _n , D ₁ -D _m and the thin film transistor switching element Q. It may be. In addition, the driving devices 400, 500, 600, and 800 may be integrated into a single chip, in which case at least one of them or at least one circuit element constituting them may be outside the single chip.

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

The signal controller 600 receives input image signals R, G, and B and an input control signal for controlling the display thereof from an external graphic controller (not shown). 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 600 properly processes the input image signals R, G, and B according to operating conditions of the liquid crystal panel assembly 300 based on the input image signals R, G, and B and the input control signal, 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 400, and the data control signal CONT2 and the processed image signal DAT are transmitted to the data driver 500. Export to).

The gate control signal CONT1 includes a scan start signal STV indicating a scan start and at least one clock signal controlling an output period of the gate-on voltage Von. The gate control signal CONT1 may also further include an output enable signal OE that defines the duration of the gate-on voltage Von.

The data control signal CONT2 is a horizontal synchronizing start signal STH indicating the start of image data transfer for one row of pixels PX and a load signal LOAD for applying a data signal to the data lines D ₁ -D _m . ) And a data clock signal HCLK. The data control signal CONT2 is also an inverted signal that inverts the voltage polarity of the data signal relative to the common voltage Vcom (hereinafter referred to as " polarity of the data signal " by reducing the " voltage polarity of the data signal for the common voltage ") RVS) may be further included.

According to the data control signal CONT2 from the signal controller 600, the data driver 500 receives the digital image signal DAT for the pixel PX in one row and corresponds to each digital image signal DAT. The gradation voltage is selected to convert the digital image signal DAT into an analog data signal and then apply it to the data lines D ₁ -D _m .

The gate driver 400 applies the gate-on voltage Von 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 . Turn on the switching element (Q) connected to. Then, the data signal applied to the data lines D ₁ -D _m is applied to the pixel PX through the switching element Q turned on.

The difference between the voltage of the data signal applied to the pixel PX and the common voltage Vcom is represented as the charging voltage of the liquid crystal capacitor C _LC , that is, the pixel voltage. The arrangement of the liquid crystal molecules varies according to the magnitude of the pixel voltage, thereby changing the polarization of light passing through the liquid crystal layer 3. The change in polarization is represented by a change in transmittance of light by a polarizer attached to the display panel assembly 300.

This process is repeated in units of one horizontal period (also referred to as "1H" and equal to one period of the horizontal sync signal (H _sync ) and the data enable signal (DE)), so that all gate lines (G ₁ -G) are repeated. _n is sequentially applied to the gate-on voltage Von to apply data signals to all the pixels PX, thereby displaying an image of one frame.

When one frame ends, the state of the inversion signal RVS applied to the data driver 500 is controlled so that the next frame starts and the polarity of the data signal applied to each pixel PX is opposite to the polarity of the previous frame. "Invert frame"). In this case, the polarity of the data signal flowing through one data line is changed (eg, row inversion and point inversion) or the polarity of the data signal applied to one pixel row is different depending on the characteristics of the inversion signal RVS within one frame. (E.g. column inversion, point inversion).

The present invention is to grasp the external illuminance or the on / off state of the backlight and accordingly display the image according to different settings. Hereinafter, a method of determining an external illuminance will be described with reference to FIGS. 3 to 9, and a method of determining an on / off state of a backlight will be described with reference to FIGS. 10 and 11. 12 to 14 illustrate a method of applying different settings to image display according to an external illuminance or an on / off state of a backlight.

First, a method of determining an external illuminance will be described with reference to FIGS. 3 to 9. In order to determine the external illuminance, a plurality of light sensors are provided in the pixel area of the liquid crystal display. 3 to 7 looks at the changed portion due to the optical sensor.

3 is a block diagram of a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 4 is an equivalent circuit diagram of one pixel of the liquid crystal display according to an exemplary embodiment of the present invention.

As shown in FIG. 3, the liquid crystal display according to the exemplary embodiment of the present invention includes a liquid crystal panel assembly 300, a gate driver 400, a data driver 500, and a sensing scan unit connected thereto. 700, a signal reader 800, a backlight 900 for irradiating light to the liquid crystal panel assembly 300, a driving voltage generator 950 for supplying the necessary voltages thereof, and a signal controller 600 for controlling them. ).

The liquid crystal panel assembly 300 is connected to a plurality of signal lines G ₁ -G _n , D ₁ -D _m , S ₁ -S _N , P ₁ -P _M , P _SG , and P _SD in an equivalent circuit. It includes a plurality of pixels arranged in a substantially matrix form.

The signal lines S ₁ -S _N and P ₁ -P _M include a plurality of sensing scan lines S ₁ -S _N for transmitting a sensing scan signal and sensing signal lines P ₁ -P _M for transmitting a sensing signal. . The sensing scan lines S ₁ -S _N extend approximately in the row direction and are substantially parallel to each other, and the sensing signal lines P ₁ -P _M extend substantially in the column direction and are substantially parallel to each other.

The signal lines P _SG and P _SD include a control voltage line P _SG for transmitting the control voltage V _SG and an input voltage line P _SD for transferring the input voltage V _SD , and extend in the row or column direction. have.

The switching element Q _S1 , such as a thin film transistor, is a three-terminal element whose control terminal and input terminal are connected to the image scanning line G ₁ -G _n and the data line D ₁ -D _m, respectively, and the output terminal is a liquid crystal. It is connected to a capacitor (C _LC ) and a holding capacitor (C _ST ).

The pixel also includes an optical sensor, which includes a sensing element Q _P connected to the signal lines P _SG and P _SD , and a switching element Q _S2 connected to the signal lines S ₁ -S _N and P ₁ -P _M. And a sense signal capacitor C _P connected thereto. However, not all pixels need to include such optical sensors, for example, one pixel of the plurality of pixels may include an optical sensor, or may include an optical sensor for each pixel placed at intervals of 1 to 2 mm. That is, the formation density of the photosensor may be adjusted as needed, and accordingly, the number of the sensing scan lines S ₁ -S _N and the sensing signal lines P ₁ -P _M may be adjusted.

The sensing element Q _P is a three-terminal element whose control terminal and input terminal are connected to the control voltage line P _SG and the input voltage line P _SD, respectively, and the output terminal is a sensing signal capacitor C _P and a switching element. Is connected to (Q _S2 ). In the sensing element Q _P , when the channel semiconductor is irradiated with light, the channel semiconductor consisting of amorphous silicon or polycrystalline silicon forms a photo current, and the photo current is generated by the input voltage V _SD applied to the input voltage line P _SD . Flows in the direction of the sense signal capacitor C _P and the switching element Q _S2 .

The sensing signal capacitor C _{P is} connected between the sensing element Q _P and the control voltage line P _SG , and accumulates charges according to the photocurrent from the sensing element Q _P to maintain a predetermined voltage. The sensing signal capacitor C _P may be omitted as necessary.

The switching element Q _S2 is also a three-terminal element whose control terminal, output terminal and input terminal are connected to the sensing scan lines S ₁ -S _N , the sensing signal lines P ₁ -P _M and the sensing elements Q _P, respectively. It is. The switching element Q _S2 is a voltage stored in the sensing signal capacitor C _P or the sensing element Q _P when a voltage for turning on the switching element Q _S2 is applied to the sensing scan lines S ₁ -S _N. The photocurrent from is output to the sensing signal lines P ₁ -P _M as the sensing signals V _P1 -V _PM .

The switching elements Q _S1 and Q _S2 and the sensing element Q _P may be formed of amorphous silicon or poly crystalline silicon thin film transistors.

The driving voltage generator 950 may input various voltages necessary for the liquid crystal display, that is, a gate on voltage V _on and a gate off voltage V _off for turning on / off the switching elements Q _S1 and Q _S2 . The voltage V _SD and the control voltage V _SG are generated.

The gate driver 400 is connected to the image scanning lines G ₁ -G _n of the liquid crystal panel assembly 300 so that the gate-on voltage V _on and the gate-off voltage V _off from the driving voltage generator 950 can be obtained. An image scanning signal consisting of a combination of the two is applied to the image scanning 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 apply a data voltage corresponding to the image data signal to the pixel.

The sensing scan unit 700 is connected to the sensing scan lines S ₁ -S _N of the liquid crystal panel assembly 300 so that the gate-on voltage V _on and the gate-off voltage V _off from the driving voltage generator 950 can be obtained. A sensing scan signal consisting of a combination of is applied to the sensing scan lines S ₁ -S _N.

Signal reading unit 800 is input a sense signal (V _P1 -P _PM) output is connected to the detection signal of the liquid crystal panel assembly _{(300) (P 1 -P M} ) via the detected signal line (P ₁ -P _M) Receive and perform predetermined signal processing.

The backlight 900 is positioned at the rear of the liquid crystal panel assembly 300 to irradiate light to the liquid crystal panel assembly 300, and typically includes a plurality of lamps.

The signal controller 600 controls operations of the gate driver 400, the data driver 500, the sensing scan unit 700, the signal reader 800, the backlight 900, and the driving voltage generator 950. .

The gate driver 400, the data driver 500, the sensing scan unit 700, or the signal reader 800 may be mounted directly on the liquid crystal panel assembly 300 in the form of a plurality of driving integrated circuit chips, or may be mounted on a flexible printed circuit. It may be mounted on a flexible printed circuit film (not shown) and attached to the liquid crystal panel assembly 300 in the form of a tape carrier package (TCP). Alternatively, the gate driver 400, the data driver 500, the sensing scan unit 700, or the signal reader 800 may be integrated in the liquid crystal panel assembly 300.

Alternatively, the gate driver 400, the data driver 500, the sensing scan unit 700, the signal reader 800, and the signal controller 600 may be referred to as a single chip (see 610 of FIG. 12). Can be made. By integrating the processing units 400, 500, 600, 700, and 800 driving the liquid crystal display in a single chip, the mounting area may be reduced and power consumption may be reduced. Of course, if necessary, the circuit elements used in each processing unit or each processing unit may be placed outside a single chip.

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

The sensing scan unit 700 sequentially applies the gate-on voltage V _on to the sensing scan lines S ₁ -S _N according to the sensing control signal CONT3 from the signal control unit 600, and the signal reading unit 800. Reads the sensing signals V _P1 -V _PM applied to the sensing signal lines P ₁ -P _M. The signal reader 800 amplifies and filters the read detection signals V _P1 -V _PM and converts them into digital signals and transmits them to the signal controller 600. The signal controller 600 performs appropriate arithmetic processing on the digital signal to find out whether or not it is touched and the position of the touch, and transmits the information to the external device, and the external device transmits an image signal based on the information to the liquid crystal display device. .

Next, the structure of the liquid crystal display according to the exemplary embodiment of the present invention will be described in detail with reference to FIGS. 5 to 7.

FIG. 5 is an example of a layout view of a liquid crystal display according to an exemplary embodiment of the present invention, and FIGS. 6 and 7 respectively illustrate the liquid crystal display of FIG. 5 along a line VI-VI ′ and VII-VII ′. One cross section.

The liquid crystal display according to the exemplary embodiment of the present invention includes a lower panel 100 and an upper panel 200 facing the lower panel 100, and a liquid crystal layer 3 interposed between the lower panel 100 and the upper panel 200. Is done.

First, as illustrated in FIGS. 5 to 7, the lower display panel 100 includes a plurality of image scanning lines 121, a plurality of sustain electrode lines 131, and a plurality of sensing scan lines on the insulating substrate 110. a sensing scanning line 127 and a plurality of control voltage lines 129 are formed.

The scan lines 121 and 127 and the control voltage line 129 mainly extend in the horizontal direction and are separated from each other, and transmit the image scan signal, the sense scan signal, and the control voltage V _SG , respectively, and each of the plurality of control terminal electrodes ( control electrodes 124, 128, 126. The control voltage line 129 includes a control voltage line 129 and an extension 123 extending from the control terminal electrode 126.

The storage electrode line 131 mainly extends in the horizontal direction and includes a plurality of protrusions constituting the storage electrode 133. The storage electrode line 131 receives a predetermined voltage such as a common voltage applied to the common electrode 270 of the upper panel 200.

Sides of the scan lines 121 and 127, the storage electrode line 131, and the control voltage line 129 are inclined with respect to the surface of the substrate 110, and the inclination angle thereof is about 30-80 ° with respect to the surface of the substrate 110.

An insulating layer 140 made of silicon nitride (SiNx) is formed on the scan lines 121 and 127, the storage electrode line 131, and the control voltage line 129.

A plurality of linear semiconductors 151 and a plurality of island-like semiconductors 156, 158, and 159 made of hydrogenated amorphous silicon (amorphous silicon is abbreviated a-Si) and the like are formed on the insulating layer 140. have. The linear semiconductor 151 extends mainly in the longitudinal direction, from which a plurality of projections 154 extend toward the control terminal electrode 124, from which the plurality of extensions 157 extend. In addition, the linear semiconductor 151 increases in width near the point where the scan lines 121 and 127, the sustain electrode line 131, and the control voltage line 129 meet, and thus the scan lines 121 and 127, the sustain electrode line 131, and the control voltage line 129. Covers a large area).

A plurality of linear and island ohmic contacts 161, 162, 164, and 165 made of a material such as n + hydrogenated amorphous silicon doped with high concentration of silicide or n-type impurities on top of the semiconductor 151. 166 and 168 are formed. The linear contact member 161 has a plurality of protrusions 163, and the protrusions 163 and the island contact members 165 are paired and positioned on the protrusions 154 of the semiconductor 151. In addition, the island contact members 162 and 164 and the island contact members 166 and 168 are also paired and positioned on the island semiconductors 156 and 158, respectively.

Side surfaces of the semiconductors 151, 156, 158, and 159 and the ohmic contacts 161, 162, 164, 165, 166, and 168 are also inclined with respect to the surface of the substrate 110, and the inclination angle is 30-80 °.

On the ohmic contact 161, 162, 164, 165, 166, 168 and the insulating layer 140, a plurality of data lines 171, a plurality of input voltage lines 179a, a plurality of sensing signal lines 179b, A plurality of output terminal electrodes 174 and 175 and a plurality of input electrode 176 are formed.

The data line 171, the input voltage line 179a, and the sensing signal line 179b mainly extend in the vertical direction and intersect the scan lines 121 and 127, the storage electrode line 131, and the control voltage line 129, respectively. Pass the sense input voltage and sense signal.

Each output terminal electrode 175 includes an extension 177 overlapping one storage electrode 133. Each vertical portion of the data line 171 includes a plurality of protrusions, and the vertical portion including the protrusions forms an input terminal electrode 173 partially surrounding one end of the output terminal electrode 175. One control terminal electrode 124, one input terminal electrode 173, and one output terminal electrode 175, together with the protrusion 154 of the semiconductor 151, form one thin film transistor (TFT). The channel of the thin film transistor is formed in the protrusion 154 between the input terminal electrode 173 and the output terminal electrode 175. This thin film transistor functions as a switching element Q _S1 .

Each input voltage line 179a includes a plurality of horizontal portions and a plurality of vertical portions, and a part of the horizontal portions of the input voltage line 179a includes a plurality of protrusions, and the horizontal portion including the protrusions includes the output terminal electrode 174. An input terminal electrode 172 is formed to partially surround one end of the. One control terminal electrode 126, one input terminal electrode 172, and one output terminal electrode 174 together with the semiconductor 156 constitute one thin film transistor (TFT), and the channel of the thin film transistor is an input terminal. Is formed in the semiconductor 156 between the electrode 172 and the output terminal electrode 174. This thin film transistor functions as a sensing element Q _P.

The output terminal electrode 174 and the input terminal electrode 176 are connected to each other. A branch extending from the sensing signal line 179b toward the input terminal electrode 176 forms the output terminal electrode 178. The pair of input terminal electrodes 176 and output terminal electrodes 178 are each separated from each other and positioned opposite to each other with respect to the control terminal electrode 128. One control terminal electrode 128, one input terminal electrode 176 and one output terminal electrode 178 together with the semiconductor 158 constitute one thin film transistor (TFT), and the channel of the thin film transistor is an input terminal. Is formed in the semiconductor 158 between the electrode 176 and the output terminal electrode 178. This thin film transistor functions as a switching element Q _S2 .

Each output terminal electrode 174 includes an extension 174a that overlaps the extension 123 of one control voltage line 129, and the sense signal capacitor C _P is the two extension 123, 174a. Is created by nesting.

The data line 171, the input voltage line 179a, the sensing signal line 179b, the output terminal electrodes 174 and 175, and the input terminal electrode 176 also scan lines 121 and 127, sustain electrode line 131, and control voltage line ( Like 129, the sides are inclined at an angle of about 30-80 degrees, respectively.

The ohmic contacts 161, 162, 164, 165, 166, and 168 may have semiconductors 151, 156, 158, and 159 thereunder, data lines 171, input voltage lines 179a, and sensing signal lines 179b thereon. ), Which exists only between the output terminal electrodes 174 and 175 and the input terminal electrode 176, serves to lower the contact resistance. The linear semiconductor 151 has an exposed portion between the input terminal electrode 173 and the output terminal electrode 175, and is not covered by the data line 171 and the output terminal electrode 175, and in most places, the linear semiconductor 151 is provided. Although the width of the 151 is smaller than the width of the data line 171, the width becomes larger at the portion where the scan lines 121 and 127, the storage electrode line 131, and the control voltage line 129 meet, so that the scan lines 121 and 127 and the storage electrode line ( 131 and the insulation between the control voltage line 129 and the data line 171 is strengthened.

Silicon nitride or oxide, which is an inorganic material, is disposed on the data line 171, the input voltage line 179a, the sensing signal line 179b, the output terminal electrodes 174 and 175, and the portion of the input terminal electrode 176 and the exposed semiconductor 151. A passivation layer 180 made of silicon is formed, and an organic insulating layer 187 made of an organic material having excellent planarization characteristics and photosensitivity is formed on the passivation layer 180. In this case, the surface of the organic insulating layer 187 has a concave-convex pattern, and the concave-convex pattern is induced to the reflective electrode 194 formed on the organic insulating layer 187 to maximize the reflection efficiency of the reflecting electrode 194.

In the passivation layer 180 and the organic insulating layer 187, contact holes 185 exposing the extension 177 of the output terminal electrode 175 are formed. The contact hole 185 may be made in various shapes such as polygon or circle shape. The sidewalls of the contact holes 185 are inclined or stepped at an angle of 30-85 °.

A plurality of pixel electrodes 190 are formed on the organic insulating layer 187.

The pixel electrode 190 includes a transparent electrode 192 and a reflective electrode 194 formed on the transparent electrode 192. The transparent electrode 192 is made of ITO or IZO, which is a transparent conductive material, and the reflective electrode 194 may be made of aluminum or an aluminum alloy, silver or silver alloy, which are opaque and have reflectivity. The pixel electrode 190 may further include a contact auxiliary layer (not shown) made of molybdenum or molybdenum alloy, chromium, titanium, or tantalum. The contact auxiliary layer secures contact characteristics between the transparent electrode 192 and the reflective electrode 194 and prevents the transparent electrode 192 from oxidizing the reflective electrode 194.

One pixel is largely divided into a transmission area TA and a reflection area RA. The transmission area TA 195 is an area where the reflection electrode 194 is removed, and the reflection area RA is a reflection electrode ( 194) exists. The organic insulating layer 187 is removed from the transmission area TA 195 so that a cell gap of the transmission area TA 195 and a cell gap of the reflection area RA are different from each other.

An opening 199 is formed on the semiconductor 156 to expose the semiconductor 156 to external light by removing the organic insulating layer 187 and the pixel electrode 190.

The pixel electrode 190 is physically and electrically connected to the extension 177 of the output terminal electrode 175 through the contact hole 185 to receive a data voltage from the output terminal electrode 175. The pixel electrode 190 to which the data voltage is applied rearranges the liquid crystal molecules of the liquid crystal layer 3 between the two by generating an electric field together with the common electrode 270.

In addition, as described above, the pixel electrode 190 and the common electrode 270 form a liquid crystal capacitor C _LC to maintain an applied voltage even after the thin film transistor is turned off. _LC holding capacitor (C _ST ) in parallel. In the storage capacitor C _ST , the extension 177 of the output terminal electrode 175 and the storage electrode 133 are made to overlap each other. The storage capacitor C _ST may be formed by overlapping the pixel electrode 190 and the adjacent image scanning line 121, and the storage electrode line 131 may be omitted.

The pixel electrode 190 overlaps the scan lines 121 and 127 and the neighboring data line 171 to increase the aperture ratio, but may not overlap.

A transparent conductive polymer or the like 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.

Meanwhile, a light blocking member 220 called a black matrix is formed on the upper panel 200 facing the lower panel 100 on a substrate 210 made of an insulating material such as transparent glass. The light blocking member 220 prevents light leakage between the pixel electrodes 190 and defines an opening area facing the pixel electrode 190.

The plurality of color filters 230 are formed on the substrate 210 and the light blocking member 220, and are disposed to substantially enter the opening region defined by the light blocking member 220. The color filters 230 disposed between two neighboring data lines 171 and arranged in the vertical direction may be connected to each other to form a band. Each color filter 230 may represent one of three primary colors such as red, green, and blue.

An overcoat 250 made of an organic material is formed on the color filter 230 and the light blocking member 220 to protect the color filter 230 and to flatten the surface.

The common electrode 270 made of a transparent conductive material such as ITO or IZO is formed on the overcoat 250.

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.

8 is a graph illustrating an output voltage of an optical sensor according to external illumination according to an embodiment of the present invention, and FIG. 9 is a circuit diagram of converting an output current of an optical sensor according to an embodiment of the present invention into an output voltage value.

Figure 8 shows the results of experimenting with the output voltage of the optical sensor according to the external illuminance. The output voltage of FIG. 8 was measured through the circuit shown in FIG. That is, in FIG. 9, an integrator is a circuit that changes a current value output from an optical sensor into a voltage. Therefore, the output voltage measured in FIG. 8 illustrates a voltage value output after integrating the current value output from the optical sensor using the integrating circuit of FIG. 9. The stronger the external light, the lower the output voltage.

The voltage value output from the photosensor is classified according to the range of the voltage value through a comparison circuit (not shown). Images are displayed with different settings according to the division. In this embodiment, three comparison circuits are installed to distinguish a total of four kinds of illumination (two bits), or one comparison circuit is installed to distinguish two kinds of illumination. If the external illumination is the darkest among the four or two types, the transmission mode is used. If the external illumination is the brightest, the reflection mode is used.

As described above, the image is displayed by adjusting the setting according to the output of the optical sensor. The setting adjustment according to the output of the optical sensor will be described later with reference to FIG. 12.

 Hereinafter, a method of detecting a state of a backlight will be described with reference to FIGS. 10 and 11.

10 is a partial circuit diagram of a signal controller according to an embodiment of the present invention, and FIG. 11 is a diagram illustrating a signal input to an FPC according to an embodiment of the present invention.

The state of the backlight is sensed through the lamp driving signal of the backlight is input to the signal controller. In the exemplary embodiment of the present invention, as shown in FIG. 10, the signal controller 600 receives a signal LED_EN for controlling the on / off of the backlight LED and determines whether the LED is in an on state or an off state. Can be checked. In the present embodiment, only the on / off of the LED is sensed so that the LED is turned on and is controlled to be used as a transmissive type when the LED is off.

Meanwhile, the signal controller 600 may be configured to receive the current itself provided to the light source in addition to the LED_EN signal. In other words, the current itself provided to the light source is received, and the comparison circuit divides the magnitude of the current into several steps (4 or more bits) and displays the image with different settings according to the classification.

In this embodiment, although the LED is used as the light source, the same applies to other light sources such as CCFL.

As described above, the state of the light source of the backlight is detected by the signal controller 600, and the image is displayed by changing the setting by using the sensed value. The display of the image by changing the setting will be described below.

Hereinafter, a method of displaying an image by changing settings of a liquid crystal display using external illuminance characteristic data or backlight state data sensed using an optical sensor will be described.

Changing the setting of the liquid crystal display may be a simple method of changing the transmission mode and the reflection mode in an embodiment of the present invention, and may change the gamma value of the liquid crystal display or the common voltage value of the liquid crystal display. In the exemplary embodiment of the present invention, the detected external illuminance characteristic data or the state data of the backlight are divided into four (2 bits) or two (1 bits) and processed.

It is preferable that the setting of the liquid crystal display device is performed by the signal controller 600.

First, the external illuminance characteristic data detected by the optical sensor is input to the signal controller 600 to classify the external illuminance characteristics into four or two types. After that, it is simply determined whether it is preferable to display an image in the transmissive mode or to display the image in the reflective mode to control each of the driving units 400, 500, and 800. Unlike the present exemplary embodiment, the drivers 400, 500, and 800 may be controlled to change the gamma value of the liquid crystal display by subdividing the value of the externally roughness characteristic data that is more complicated.

On the other hand, when using the state data of the backlight, the signal controller 600 analyzes the data to determine whether it is in an on state or an off state. After that, the image is displayed in the transmissive mode in the on state, and the image is displayed in the reflective mode in the off state. Unlike the present exemplary embodiment, each of the drivers 400, 500, and 800 may be controlled to receive a current value input to the lamp of the backlight to subdivide the backlight state and change the gamma value accordingly.

Even when both data (external illuminance characteristic data and backlight state data) are used, the signal controller 600 separates both data and merges them, thereby changing the gamma value. According to this embodiment, each of the divided data is multiplied and then merged to change the gamma value accordingly and to control the driving units 400, 500, and 800.

Meanwhile, as shown in FIG. 12, the setting may be changed by using a separate processor.

FIG. 12 is a schematic view illustrating a driving sequence of a liquid crystal display according to an exemplary embodiment of the present invention, and illustrates a liquid crystal display used in a mobile device such as a cellular phone.

The microprocessor unit 10, which is a mobile device control processor, is used to grasp external illumination characteristic data or backlight state data detected by an optical sensor and transmit a control signal according to the driving IC 610. The driver IC 610 includes a gate driver 400, a data driver 500, a sensing scan unit 700, a signal reader 800, a signal controller 600, and the like on one chip. This is because mobile devices such as mobile phones have a small space and a small size of the liquid crystal display device, which can be formed as a single chip.

The signal transmitted to the microprocessor unit 10 is external illuminance characteristic data or state data of the backlight detected by the optical sensor, and both data may be used.

First, the external illuminance characteristic data detected by the optical sensor is input to the microprocessor unit 10 to distinguish external illuminance characteristics. Thereafter, it is determined whether to display an image in a transmission mode or a display mode in a reflection mode on the basis of the divided data, and transfers the image to the driving IC 610. More specifically, the driving IC 610 is controlled to change the gamma value of the liquid crystal display by subdividing the value of the input external illuminance characteristic data.

On the other hand, when the state data of the backlight is used, the microprocessor unit 10 receiving the state data determines whether the backlight is on or off and accordingly determines whether to display the image in the transmission mode or the reflection mode. On the other hand, unlike the present embodiment, when the state data of the backlight is subdivided, the driving IC 610 is controlled to change the gamma value according to the input backlight state data.

Even when both data (external illuminance characteristic data and backlight state data) are used, the microprocessor unit 10 analyzes both data and simply determines whether to display the image in the transmission mode or the reflection mode. In addition, the driving IC 610 is controlled to change the gamma value by subdividing the input backlight state.

On the other hand, there are a variety of ways to change the gamma value, of which the gamma value can be changed by changing the gray voltage value according to the input image data value, and by changing the common voltage, the gray voltage value is relatively To change the gamma value. The former is shown in FIG. 13 and the latter is shown in FIG.

13 is a circuit diagram of a gray voltage generator of a liquid crystal display according to an exemplary embodiment of the present invention.

The signal control unit 600 or the microprocessor unit 10 which has received both data (external illuminance characteristic data and backlight state data) changes the GVDD value so that the gradation voltage value of the portion that needs to be changed is changed accordingly. do. The GVDD voltage is a voltage input to a resistor string for generating a gray voltage, and divides the input GVDD voltage into a resistor string to generate a gray voltage. Two resistance strings are shown in the gray voltage generator 800 of FIG. 13, but a different number of resistance strings may be formed. When the GVDD value is changed by the gray voltage generator 800, the output gray voltage is changed while the voltage applied to the resistor connected thereto is changed. As a result, the data voltage corresponding to the image data is changed.

14 is a diagram illustrating a common voltage generated according to an embodiment of the present invention.

In the common voltage, the common voltage generator 630 of FIG. 14 determines VCOMH, which is the maximum value of the common voltage, and an amplitude falling therefrom, thereby generating a common voltage.

The signal controller 600 or the microprocessor unit 10 that has received both data (external illuminance characteristic data and backlight state data) determines the change value of the common voltage accordingly, and then the common voltage generator 630 as shown in FIG. 14. Change control output VCOMH value or VCOM Amp value. When the common voltage is changed as described above, the difference voltage between the common voltage and the data voltage is different even though the data voltage is the same, and thus the image quality is changed by changing the voltage applied to the actual liquid crystal.

In summary, the present invention is to change the display characteristics of the liquid crystal display using data obtained by detecting an external illuminance with an optical sensor or data on a backlight state. According to the exemplary embodiment, when the gray voltage is changed as shown in FIG. 13, the common voltage is changed as shown in FIG. 14. In general, both data (external illuminance characteristic data and backlight state data) are determined and controlled by the signal controller 600. However, in a mobile device such as a mobile phone, the microprocessor unit 10 may be used to determine and control both data (external illumination characteristic data and backlight state data).

As described above, the transflective liquid crystal display grasps the external illuminance or the state of the backlight to selectively apply the reflection mode or the transmission mode, or change the gamma value to display an image, thereby improving the image quality and allowing the user to view the image. Make it clear and clear.

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.

Claims (15)

Measuring external illuminance using an optical sensor formed on the liquid crystal display panel; Classifying the measured external illuminance using a comparison circuit, Transmitting the separated external illuminance to a microprocessor unit; and And transmitting the control signal of the liquid crystal display panel according to the external illuminance. In claim 1, And a control signal of the liquid crystal display panel is a control signal for changing a data voltage applied to the liquid crystal display panel. In claim 1, And a control signal for changing the common voltage applied to the liquid crystal display panel. In claim 1, The step of classifying the measured external illuminance by using a comparison circuit A method of driving a display device that divides external illuminance into two or four stages. In claim 4, And driving in a reflection mode when the external illuminance is the brightest, and driving in a transmission mode when the external illuminance is the darkest. Transmitting a signal input to the light source of the backlight to the microprocessor unit, Determining the state of the backlight according to the signal input to the light source; And transmitting the control signal of the liquid crystal display panel according to the state of the backlight. In claim 6, And driving in a reflective mode when the backlight is turned off and driving in a transmissive mode when the backlight is turned on. A transflective liquid crystal display panel comprising an optical sensor, A common voltage generator configured to generate a common voltage applied to the liquid crystal display panel; A driver configured to generate a voltage applied to the liquid crystal display panel; A gray voltage generator which generates a gray voltage applied to the driver; A signal controller for controlling the driver and the gray voltage generator; A microprocessor unit for applying a control signal to the signal controller, And the microprocessor unit receives an output of the optical sensor to determine an external illuminance and then changes display characteristics of the liquid crystal display panel according to the determined illuminance. In claim 8, The change of display characteristics of the liquid crystal display panel changes the gray voltage generated by the gray voltage generator. In claim 8, Changing display characteristics of the liquid crystal display panel changes the common voltage generated by the common voltage generator. In claim 8, The common voltage generator, the driver, the gray voltage generator, and the signal controller are formed of one chip. Transflective liquid crystal display panel, A backlight unit including a light source to provide light to the liquid crystal display panel; A common voltage generator configured to generate a common voltage applied to the liquid crystal display panel; A driver configured to generate a voltage applied to the liquid crystal display panel; A gray voltage generator which generates a gray voltage applied to the driver; A signal controller for controlling the driver and the gray voltage generator; A microprocessor unit for applying a control signal to the signal controller, And the backlight unit outputs data on the state of the light source, and the microprocessor unit receives data on the state of the light source to change display characteristics of the liquid crystal display panel according to the state of the light source. In claim 12, The change of display characteristics of the liquid crystal display panel changes the gray voltage generated by the gray voltage generator. In claim 12, Changing display characteristics of the liquid crystal display panel changes the common voltage generated by the common voltage generator. In claim 12, The common voltage generator, the driver, the gray voltage generator, and the signal controller are formed of one chip.

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