KR20080021380A - Liquid crystal display - Google Patents

Abstract

An LCD(Liquid Crystal Display) is provided to improve the resolution of a sensing unit without increasing the number of sensing elements to achieve an accurate sensing operation, thereby reducing the area of a driver and decrease power consumption. An LCD includes a display panel, a plurality of sensors, a sense signal processor(800) and a touch determination unit(700). The plural sensors are formed in the display panel and output a sense signal according to a touch given to the display panel. The sense signal processor receives the sense signal, processes the received sense signal and generates sense data. The touch determination unit determines the position of the display panel to which the touch is applied from the sense data. Each of the sensors includes first, second and third sensing parts which respectively output first, second and third sense signals. The touch determination unit compares the first, second and third sense signals to determine the position of the display panel to which the touch is applied.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY}

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

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 illustrating a liquid crystal display according to an exemplary embodiment of the present invention from the perspective of a sensing unit.

4A and 4B are equivalent circuit diagrams of a sensing unit of a liquid crystal display according to an exemplary embodiment of the present invention.

5 is a perspective view schematically illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

6A, 6B and 6C are graphs showing various examples of detection results of a liquid crystal display according to an embodiment of the present invention.

FIG. 7A is an equivalent circuit diagram of a plurality of sensing units connected to one sensing data line in a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 7B is an equivalent circuit diagram briefly illustrating FIG. 7A.

8A and 8B are waveform diagrams illustrating a sensing operation of a liquid crystal display according to an embodiment of the present invention.

9 is an equivalent circuit diagram illustrating a connection relationship between a sensing data line and a sensing data processor in a liquid crystal display according to an exemplary embodiment of the present invention.

The present invention relates to a liquid crystal display device.

The liquid crystal display is one of the flat panel display devices most widely used. 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 the liquid crystal molecules of the liquid crystal layer and controlling the polarization of incident light to display an image.

A touch screen panel is a device that touches a finger or a touch pen (stylus) on the screen to write and draw letters or pictures, or execute icons to perform a desired command on a machine such as a computer. .

A liquid crystal display with a touch screen panel may find out whether a user's finger or a touch pen touches the screen and contact position information.

However, such a liquid crystal display device has problems such as a cost increase due to a touch screen panel, a decrease in yield due to a process of adhering the touch screen panel to a liquid crystal display panel, a decrease in luminance of the liquid crystal panel, and an increase in product thickness.

Therefore, in order to solve these problems, a technology for embedding a sensing element in a liquid crystal display device instead of a touch screen panel has been developed.

The sensing element detects a change in light or pressure applied to a screen by a user's finger or the like so that the liquid crystal display may determine whether the user's finger or the like has touched the screen and contact position information.

In order to more accurately determine whether a screen is touched or positioned by using a sensing element, more sensing elements should be embedded in the liquid crystal display. However, when many sensing elements are incorporated in the liquid crystal display, the aperture ratio of the liquid crystal display is reduced.

An object of the present invention is to provide a liquid crystal display device which performs a more accurate sensing operation by increasing the resolution of the sensing unit without increasing the number of sensing elements.

According to an exemplary embodiment of the present invention, a liquid crystal display device includes a plurality of sensing units formed on a display panel and the display panel and outputting a sensing signal according to a contact with the display panel, and receiving the sensing signal to process the sensing data. A sensing signal processor to generate and a touch determination unit to calculate the sensing data to determine a location of the touch point, wherein the sensing units are adjacent to each other and output first, second and third sensing signals, respectively; And a second and a third sensing unit, wherein the touch determining unit compares the first, second and third sensing signals to determine the contact point with respect to the display panel.

The value of the second sensing signal may be greater than the values of the first and third sensing signals.

If the value of the first sensing signal and the value of the third sensing signal are substantially the same, the contact point is the second sensing unit, and if the value of the first sensing signal is greater than the value of the third sensing signal, the contact is made. The point is between the first sensing unit and the second sensing unit, and if the value of the third sensing signal is greater than the value of the first sensing signal, the contact point is between the second sensing unit and the third sensing unit. Can be.

F1 = {F (n) -F (n-1)}-{F (n) -F (n + 1)}, provided that F (n-1), F (n) and F (n + 1) Is the value of the first, second and third sensing signals, respectively, and if -S <F1 <S (where S = F (n) / 2) is satisfied, the contact point is the second sensing point. Negative, and if F1> S is satisfied, the contact point is between the second sensing unit and the third sensing unit, and if F1 <-S, the contact point is the second sensing unit and the first sensing unit. It can be between wealth.

And a sensing data line formed on the display panel, wherein the sensing unit is connected to the sensing data line, the variable capacitor having capacitance changed by the pressure, a reference capacitor connected to the sensing data line, And first and second reset transistors connected to the sensing data lines and supplying first and second reset voltages to the sensing data lines at different times, respectively.

The display device may further include a plurality of output transistors connected to the sensing data line and generating an output signal based on the sensing data signal flowing through the sensing data line and outputting the output signal to the sensing signal processor.

The sensing signal processor may include a plurality of integrators that generate the sensing signal by integrating the output signal.

The integrator may comprise an amplifier and a capacitor.

The first reset transistor may apply the first reset voltage to the sense data line before the sense signal processor generates the sense signal.

The second reset transistor may apply the second reset voltage to the sense data line after the sense signal processor generates the sense signal.

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, 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, which is an example of a display device according to an exemplary embodiment, will now be described in detail with reference to FIGS. 1 to 5.

1 is a block diagram of a liquid crystal display according to an embodiment of the present invention, which is a block diagram of the liquid crystal display shown in terms of a pixel, and FIG. 2 is a pixel of the liquid crystal display according to an embodiment of the present invention. Equivalent circuit diagram for. 3 is a block diagram of a liquid crystal display according to an exemplary embodiment of the present invention, which is a block diagram of the liquid crystal display according to a sensing unit, and FIGS. 4A and 4B illustrate a liquid crystal display according to an exemplary embodiment of the present invention. An equivalent circuit diagram for one sensing unit is shown. 5 is a schematic diagram of a liquid crystal display according to an exemplary embodiment of the present invention.

1 and 3, a liquid crystal display according to an exemplary embodiment of the present invention may include a liquid crystal panel assembly 300, an image scanning unit 400, an image data driver 500, and a liquid crystal panel assembly 300 connected thereto. A sensing signal processor 800, a gray voltage generator 550 connected to the image data driver 500, a contact determiner 700 connected to the sensing signal processor 800, and a signal controller 600 for controlling them. .

Referring to FIG. 1, 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 pixels PX connected thereto and arranged in a substantially matrix form. do. Referring to FIG. 3, the liquid crystal panel assembly 300 may further include a plurality of sensing signal lines SY ₁ -SY _N , SX ₁ -SX _M , and a plurality of sensing units SU connected to the plurality of sensing signal lines SY ₁ -SY _N and SX ₁ -SX _M. It further includes.

On the other hand, referring to FIGS. 2, 4A, and 4B, the liquid crystal panel assembly 300, from a structural point of view, may include the thin film transistor array panel 100 and the common electrode panel 200 facing each other and the liquid crystal interposed therebetween. Layer 3. The liquid crystal panel assembly 300 may also include at least one polarizer (not shown).

The display signal lines G ₁ -G _n and D ₁ -D _m are a plurality of display scan lines G ₁ -G _n for transmitting a display scan signal and display data lines D ₁ -D _m for transmitting a display data signal. and including a sensing signal _{(SY 1 -SY N, SX 1} -SX M) detects a plurality of horizontal sensing data lines for transmitting a data signal (SY ₁ -SY _N) and a plurality of vertical sensing data line (SX ₁ - SX _M ). 4A and 4B, the sensing signal line also includes a plurality of reference voltage lines RL carrying a reference voltage. The reference voltage line RL may be omitted as necessary.

The display signal lines G ₁ -G _n , D ₁ -D _m and the sensing signal lines SY ₁ -SY _N , SX ₁ -SX _M are provided on the thin film transistor array panel 100. The display scan lines G ₁ -G _n and the horizontal sensing data lines SY ₁ -SY _N extend substantially in the row direction and are substantially parallel to each other, and the display data lines D ₁ -D _m and the vertical sensing data lines ( SX ₁ -SX _M ) extend in approximately the column direction and are substantially parallel to each other. The reference voltage line RL extends in the row or column direction.

Referring to FIG. 2, the pixels of each pixel PX, for example, the i-th row (i = 1, 2, ..., n) and the j-th column (j = 1, 2, ..., m) are displayed in the display signal line G. _i , D _j ) and a switching element Q connected thereto, and 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 of a thin film transistor or the like provided in the thin film transistor array panel 100, the control terminal of which is connected to the display scan line G _i , and the input terminal of the display data line D _j . The output terminal is connected to the liquid crystal capacitor Clc and the storage capacitor Cst. In this case, the thin film transistor includes amorphous silicon or poly crystalline silicon.

The liquid crystal capacitor Clc has two terminals, the pixel electrode 191 of the thin film transistor array panel 100 and the common electrode 270 of the common electrode display panel 200, and the liquid crystal layer 3 between the two electrodes 191 and 270. Functions as a dielectric.

The pixel electrode 191 is connected to the switching element Q, and the common electrode 270 is formed on the entire surface of the common electrode display panel 200 and receives the common voltage Vcom.

Unlike in FIG. 2, the common electrode 270 may be provided in the thin film transistor array panel 100. In this case, at least one of the two electrodes 191 and 270 may be linear or rod-shaped.

The storage capacitor Cst, which serves as an auxiliary role of the liquid crystal capacitor Clc, is formed by overlapping a separate signal line (not shown) and the pixel electrode 191 provided in the thin film transistor array 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 Cst may be formed such that the pixel electrode 191 overlaps the front end display scan line G _i-1 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.

FIG. 2 illustrates that each pixel PX includes a color filter 230 representing one of the primary colors in an area of the common electrode display panel 200 corresponding to the pixel electrode 191 as an example of spatial division. .

Unlike FIG. 2, the color filter 230 may be formed above or below the pixel electrode 191 of the thin film transistor array panel 100.

Three pixels PX that display three primary colors and are adjacent to each other are called dots, and dots are a basic unit of an image. The number of rows and columns of dots indicates the resolution of the liquid crystal display device. However, one dot may be formed of four or more pixels PX, and in this case, some pixels PX may display white.

 The sensing unit SU may have a structure shown in FIG. 4A or a structure shown in FIG. 4B.

The sensing unit SU1 shown in FIG. 4A includes a variable capacitor Cv, a sensing data line SL, and a reference voltage line connected to a horizontal or vertical sensing data line (hereinafter, referred to as a sensing data line) indicated by a reference numeral SL. And a reference capacitor Cp connected between the RLs.

The reference capacitor Cp is formed by overlapping the reference voltage line RL and the sensing data line SL of the thin film transistor array panel 100 with an insulator interposed therebetween.

The variable capacitor Cv has the sensing data line SL of the thin film transistor array panel 100 and the common electrode 270 of the common electrode display panel 200 as two terminals, and the liquid crystal layer 3 between the two terminals functions as a dielectric. do. The capacitance of the variable capacitor Cv is changed by an external stimulus such as a user's touch applied to the liquid crystal panel assembly 300. The external stimulus may be a pressure. For example, when pressure is applied to one of the thin film transistor array panel 100 and the common electrode display panel 200, the distance between the two terminals of the variable capacitor Cv is changed to change the variable capacitor ( The capacitance of Cv) changes.

When the capacitance of the variable capacitor Cv changes, the magnitude of the contact voltage Vp between the reference capacitor Cp and the variable capacitor Cv changes.

The contact voltage Vp flows on the sensing data line SL as a sensing data signal, and based on the contact voltage Vp, the contact voltage Vp may be determined.

The sensing unit SU2 illustrated in FIG. 4B includes a switch SWT connected to the sensing data line SL.

The switch SWT has two terminals, the common electrode 270 of the common electrode display panel 200 and the sensing data line SL of the thin film transistor array panel 100, and at least one of the two terminals protrudes to contact the user. The two terminals can be contacted. When two terminals of the switch SWT contact each other, the common voltage Vcom of the common electrode 270 is transferred to the sensing data line SL. When the sensing unit SU2 is applied, the reference voltage line RL illustrated in FIG. 4A may be omitted.

The vertical position of the contact point can be determined by analyzing the sensing data signal flowing through the horizontal sensing data line (SY ₁ -SY _N ), and the sensing data signal flowing through the vertical sensing data line (SX ₁ -SX _M ) is analyzed. The horizontal position of the contact point can be determined.

The sensing unit SU is disposed between two adjacent pixels PX.

A pair of the horizontal and vertical sensing data line _{(SY 1 -SY N, SX 1} -SX M) is connected thereto and defines a sensing unit (SU) of the pair is disposed adjacent to the region in which they cross. The density of the pair of sensing units SU may be, for example, about one quarter of the dot density.

An example in which the density of the sensing unit pairs is 1/4 of the dot density is that the density of the sensing unit pairs in one row is 1/2 of the dot density in one row and the sensing unit in one column. The case where the density of a (SU) pair is 1/2 of the dot density in one column is mentioned.

By matching the detection unit SU density and the dot density to such an extent, the liquid crystal display device may be applied to high precision applications such as character recognition. Of course, the resolution of the sensing unit SU may be higher or lower as necessary.

Meanwhile, by comparing a plurality of sensing data signals output from adjacent sensing units SU, it is possible to determine whether a contact point is a portion of each sensing unit SU or a point between each sensing unit SU. . Therefore, the position of the contact point can be determined more precisely with the same number of sensing units SU. This will be described in more detail later.

Referring back to FIGS. 1 and 3, the gray voltage generator 550 generates two sets of gray voltage sets (or reference gray voltage sets) related to the transmittance of the pixel. One of the two sets has a positive value for the common voltage Vcom and the other set has a negative value.

The image scanning unit 400 is connected to the image scanning lines G ₁ -G _n of the liquid crystal panel assembly 300 to gate-on voltage Von for turning on the switching element Q, and gate-off voltage Voff for turning off. ) Is applied to the image scanning lines G ₁ -G _n .

The image data driver 500 is connected to the image data lines D ₁ -D _m of the liquid crystal panel assembly 300, and selects a gray voltage from the gray voltage generator 550 and uses the image data as the image data signal. Applies to lines D ₁ -D _m . However, when the gray voltage generator 550 provides only a predetermined number of reference gray voltages instead of providing all voltages for all grays, the image data driver 500 divides the reference gray voltages so that the grays for all grays are divided. Generates a voltage and selects an image data signal among them.

Detection signal processing section 800 is connected to the sensing of the liquid crystal panel assembly 300, a data line _{(SY 1 -SY N, SX 1} -SX M) detects the data line _{(SY 1 -SY N, SX 1} -SX M) to After receiving the sensed data signal output through the signal processing such as amplification, filtering and the like to analog-to-digital conversion to generate a digital sense signal (DSN).

The touch determining unit 700 receives the digital sensing signal DSN from the sensing signal processing unit 800, performs a predetermined calculation process, determines whether the contact is made, and the contact position, and then sends the contact information INF to the external device. The touch determination unit 700 may monitor an operation state of the sensing unit SU based on the digital sensing signal DSN and control signals applied to the sensing unit SU.

The signal controller 600 controls operations of the image scanning unit 400, the image data driver 500, the gray voltage generator 550, and the detection signal processor 800.

Each of the driving devices 400, 500, 550, 600, 700, 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 ( 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, 550, 600, 700, and 800 are connected to signal lines G ₁ -G _n , D ₁ -D _m , SY ₁ -SY _N , SX ₁ -SX _M and thin film transistors ( Q) together with the liquid crystal panel assembly 300 may be integrated.

Referring to FIG. 5, the liquid crystal panel assembly 300 is divided into a display area P1, an edge area P2, and an exposure area P3. Most of the pixel PX, the sensing unit SU, and the signal lines G ₁ -G _n , D ₁ -D _m , SY ₁ -SY _N , SX ₁ -SX _M , RL are positioned in the display area P1. . The common electrode display panel 200 includes a black matrix (not shown), and the black matrix covers most of the edge region P2 to block light from the outside. The common electrode panel 200 is smaller than the thin film transistor array panel 100 so that a portion of the thin film transistor array panel 100 is exposed to form an exposed area P3, and a single chip 610 is mounted on the exposed area P3. And a flexible printed circuit board 620 is attached.

The single chip 610 is a driving device for driving a liquid crystal display, that is, an image driver 400, an image data driver 500, a gray voltage generator 550, a signal controller 600, and a contact determiner ( 700, and a sensing signal processor 800. By integrating the driving devices 400, 500, 550, 600, 700, and 800 in a single chip 610, the mounting area may be reduced, and power consumption may be reduced. Of course, if desired, at least one of them or at least one circuit element constituting them may be outside the single chip 610.

The image signal lines G ₁ -G _n , D ₁ -D _m and the sensing data lines SY ₁ -SY _N , SX ₁ -SX _M extend to the exposure area P3 so that the corresponding driving devices 400, 500, 800 ).

The FPC board 620 receives a signal from an external device and transmits the signal to the single chip 610 or the liquid crystal panel assembly 300, and an end is usually formed of a connector (not shown) to facilitate connection with the external device. .

Next, the display operation and the detection operation of the liquid crystal display will be described in more 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 device (not shown). The input video signals R, G, and B contain luminance information of each pixel PX, and the luminance is a predetermined number, for example, 1024 (= 2 ¹⁰ ), 256 (= 2 ⁸ ), or 64 (= 2 ⁶ ) It has gray. 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 receives the input image signals R, G, and B based on the input image signals R, G, and B and the input control signal, and generates operating conditions of the liquid crystal panel assembly 300 and the image data driver 500. Process the image scan control signal CONT1, the image data control signal CONT2, the sensing data control signal CONT3, and the like, and then output the image scan control signal CONT1 to the image scan unit 400. The image data control signal CONT2 and the processed image signal DAT are sent to the image data driver 500, and the sensing data control signal CONT3 is sent to the detection signal processor 800.

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

The image data control signal CONT2 is a load signal for applying the image data signal to the horizontal synchronization start signal STH indicating the start of transmission of the image data DAT in one pixel row and the image data lines D ₁ -D _m . LOAD) and data clock signal HCLK. The image data control signal CONT2 also inverts the voltage polarity of the image data signal (hereinafter referred to as "polarity of the image data signal" by reducing the "voltage polarity of the image data signal with respect to the common voltage") with respect to the common voltage Vcom. The inverting signal RVS may be further included.

In response to the image data control signal CONT2 from the signal controller 600, the image data driver 500 receives the digital image signal DAT for the pixel PX of one pixel row, and each digital image signal DAT. By converting the digital image signal DAT into an analog image data signal by selecting a gray scale voltage corresponding to), it is applied to the corresponding image data lines D ₁ -D _m .

The image scanning unit 400 applies the gate-on voltage Von to the image scanning line G ₁ -G _n in response to the image scanning control signal CONT1 from the signal controller 600, thereby applying the image scanning line G ₁ -G. _n ) turns on the switching element Q connected. Then, the image data signal applied to the image data lines D ₁ -D _m is applied to the pixel PX through the turned-on switching element Q.

The difference between the voltage of the image data signal applied to the pixel PX and the common voltage Vcom is shown as the charging voltage of the liquid crystal capacitor Clc, 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 as a change in the transmittance of light by the polarizer attached to the liquid crystal panel assembly 300, and thus a desired image may be displayed.

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 Hsync and the data enable signal DE), thereby reproducing all image scanning lines G ₁ -G _n. ), The gate-on voltage Von is sequentially applied to the image data signal to all the pixels PX, thereby displaying an image of one frame.

When one frame ends, the next frame starts and the state of the inversion signal RVS applied to the image data driver 500 is controlled so that the polarity of the image data signal applied to each pixel PX is opposite to that of the previous frame. ("Frame inversion"). In this case, the polarity of the image data signal flowing through one image data line is changed (eg, inversion of a row, inversion of a point) according to the characteristics of the inversion signal RVS within one frame, or the polarity of the image data signal applied to one pixel row. May differ from one another (eg, nirvana, point inversion).

The sensing signal processing unit 800 flows through the sensing data line SY ₁ -SY _N , SX ₁ -SX _M in a porch section between the frame once every frame according to the sensing data control signal CONT3. Read the sense data signal. In the porch section, since the sensing data signal is less affected by the driving signals from the image scanning unit 400, the image data driver 500, and the like, the reliability of the sensing data signal is increased. However, such a read operation is not necessarily performed every frame, and may be performed once every plurality of frames as necessary.

Then, the sensing signal processor 800 converts the read analog sensing data signal into a digital sensing signal DSN after signal processing such as amplification and filtering, and sends it to the contact plate end 700.

The touch determination unit 700 receives a digital sensing signal DSN, performs appropriate arithmetic processing to find out whether a contact is made and a contact position, and transmits the same to an external device, and the external device transmits the image signals R, G, and B based thereon. Transfer to the liquid crystal display device.

In this case, the touch determining unit 700 stores three sensing data signals respectively output from three neighboring sensing units SU, and compares them. As a result, it is determined whether the position of the contact point is an area between each detection unit SU or an area between each detection unit SU. In more detail, when the sensing unit SU which outputs the highest sensing data signal among the three sensing units SU is positioned, the sensing data signals of the three sensing units SU are compared. If the sensing data signal values of both sensing units SU are within the same range, the contact point is the middle sensing unit SU area. If the sensing data signal value of the left sensing unit SU is greater than the right sensing unit SU based on the center sensing unit SU, the contact point is an area between the left sensing unit SU and the center sensing unit SU. . If the sensing data signal value of the right sensing unit SU is larger than the left sensing unit SU, the contact point is an area between the right sensing unit SU and the center sensing unit SU. Therefore, it is possible to determine the contact position more precisely with only the sensing unit SU of the same number.

For example, when the (n-1) th detection unit SU, the n th detection unit SU, and the (n + 1) th detection unit SU are adjacent to each other, an output from each detection unit SU is performed. The values of the sensed data signals are referred to as F (n-1), F (n) and F (n + 1). When F (n) is the largest of the three values, F1 is defined by the following equation.

F1 = {F (n) -F (n-1)}-{F (n) -F (n + 1)}

At this time, if -S <F1 <S, the contact point is the n-th detection unit (SU) region. Here, S is a minimum value that can determine that F (n-1) and F (n + 1) are in substantially the same area, and may be, for example, F (n) / 2.

Also, if F1> S, the contact point is an area between the nth sensing unit SU and the (n + 1) th sensing unit SU. If F1 <-S, the contact point is the (n-1) th sensing unit SU. ) And the n-th detection unit SU.

Next, an example of a sensing operation of the liquid crystal display according to the exemplary embodiment of the present invention will be described with reference to FIGS. 6A, 6B, and 6C.

6A, 6B, and 6C are graphs illustrating various examples of sensing results of a liquid crystal display according to an exemplary embodiment of the present invention.

6A, 6B, and 6C, the horizontal direction represents the number of sensing data lines and the vertical direction represents the sensing signal mV. Here, the sense signal will be a digital value substantially, but is represented as an analog value for convenience.

6A, 6B, and 6C, when the sensing signals of the 18th, 19th, and 20th sensing data lines are compared, the sensing signals of the 19th sensing data lines are the highest in all three cases, but the sensing signals of the 18th and 20th sensing data lines are the highest. Are all different.

Referring to FIG. 6A, the sensing signal of the 20th sensing data line is higher than the sensing signal of the 18th sensing data line. In other words, the detection signal of the 20th sensing data line is smaller than the sensing signal of the 18th sensing data line. In this case, therefore, the contact point is between the 19th sensing data line and the 20th sensing data line.

Referring to FIG. 6B, the sensing signal of the 18th sensing data line is higher than the sensing signal of the 20th sensing data line. That is, the difference from the detection signal of the 19th sensing data line is smaller than that of the 20th sensing data line. In this case, therefore, the contact point is between the 19th sensing data line and the 18th sensing data line.

Referring to FIG. 6C, the sensing signal of the 18th sensing data line and the sensing signal of the 20th sensing data line may be substantially in the same range. That is, the difference between the sensing signal of the 19th sensing data line is the same as the sensing signal of the 20th sensing data line and the sensing signal of the 18th sensing data line. In this case, therefore, the contact point is the 19th sense data line portion.

As described above, even though the number of sensing data lines is the same, the contact point can be determined more precisely by comparing the sensing signals, thereby doubling the sensing resolution.

Next, the liquid crystal display when the sensing unit SU1 illustrated in FIG. 4A is applied will be described in more detail with reference to FIGS. 7A to 8B.

FIG. 7A is an equivalent circuit diagram of a plurality of sensing units connected to one sensing data line in a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 7B is an equivalent circuit diagram schematically illustrating the same, and FIGS. 8A and 8B illustrate the present invention. A timing diagram for a sensing operation of a liquid crystal display according to an embodiment of the present invention.

As shown in FIGS. 7A and 7B, the liquid crystal panel assembly 301 of the present exemplary embodiment may include a plurality of sensing data lines SL shown in FIG. 3 and a plurality of sensing units connected to each sensing data line SL. (SU1), first and second reset transistors Qr1 and Qr2 and output transistors Qs, and a plurality of output data lines OL connected to the output transistor Qs. That is, a plurality of variable capacitors Cv and a plurality of reference capacitors Cp are connected to one sensing data line SL, and the first reset transistor Qr1 and the first reset transistor Qr1 are respectively connected to different ends of the sensing data line SL. 2 reset transistor Qr2 and output transistor Qs are connected. The variable capacitor Cv is connected to the common voltage Vcom and the reference capacitor Cp is connected to the reference voltage Vp. The sensing signal processor 801 includes an amplifier AP, a capacitor Cf, and a switch SW.

As described above, since the plurality of variable capacitors Cv are formed using the sensing data line SL and the common electrode 270 as two terminals, the plurality of variable capacitors Cv include one variable capacitor Cv shown in FIG. 6B. In practice, the capacitance of the variable capacitor Cv 'is substantially uniformly distributed along one sensing data line SL. In addition, as illustrated in FIG. 7B, the plurality of reference capacitors Cp may also be represented by one reference capacitor Cp ′ corresponding to the variable capacitor Cv ′.

The first and second reset transistors Qr1 and Qr2 are three-terminal elements such as thin film transistors, and control terminals thereof are connected to the first and second reset signals RST1 and RST2, respectively, and the input terminals thereof are the first and second reset transistors Qr1 and Qr2. The second reset voltages Vr1 and Vr2 are respectively connected, and the output terminal is connected to the sensing data line SL. The first and second reset transistors Qr1 and Qr2 are positioned at the edge region P2 of the liquid crystal panel assembly 301 and according to the first and second reset signals RST1 and RST2, the first and second reset voltages Vr1 and Vr2 are supplied to the sense data line SL.

The output transistor Qs is also a three-terminal element such as a thin film transistor, the control terminal of which is connected to the sensing data line SL, the input terminal of which is connected to the input voltage Vs, and the output terminal of the output data line ( OL). The output transistor Qs is also positioned in the edge region P2 of the liquid crystal panel assembly 301 and generates an output signal based on the sensing data signal flowing through the sensing data line SL. An output current is mentioned as an output signal. Alternatively, the output transistor Qs may generate a voltage as an output signal.

The output data line OL is connected to the amplifier AP of the sensing signal processor 801.

The amplifier AP has an inverting terminal (-), a non-inverting terminal (+) and an output terminal, the inverting terminal (-) is connected to the output data line OL, and between the inverting terminal (-) and the output terminal The capacitor Cf and the switch SW are connected, and the non-inverting terminal + is connected to the reference voltage Va. The amplifier AP and the capacitor Cf generate a sense signal Vo by integrating the output current from the output transistor Qs for a predetermined time as a current integrator.

Referring to FIG. 8A, the liquid crystal display according to the present exemplary embodiment performs a sensing operation in a porch section between frames as described above, and particularly, in a front porch section ahead of the vertical sync signal Vsync. It is desirable to perform the operation.

The common voltage Vcom has a high level and a low level and swings the high level and the low level every 1H.

The first and second reset signals RST1 and RST2 have a gate on voltage Von for turning on the first and second reset transistors Qr1 and Qr2, and a gate off voltage Voff for turning off the first and second reset transistors Qr1 and Qr2, respectively. The gate-on voltage Von of the first reset signal RST1 is applied when the common voltage Vcom is at a high level. When the gate-on voltage Von is applied to the first reset transistor Qr1, the first reset voltage Vr1 is applied to the sensing data line SL to initialize the sensing data line SL.

When the first reset signal RST1 reaches the gate-off voltage Voff, the sensing data line SL is in a floating state and is based on a change in the capacitance of the variable capacitor Cv 'and a change in the common voltage Vcom. The sense data signal is varied. Meanwhile, after the first reset signal RST1 changes to the gate-off voltage Voff, the switching signal Vsw is applied to the switch SW to discharge the voltage charged in the capacitor Cf. Thereafter, when a predetermined time elapses, the sensing signal processor 801 reads the sensing signal Vo. In this case, the time for reading the sensing signal Vo may be set within 1H after the first reset signal RST1 becomes the gate-off voltage Voff. That is, it is preferable to read the sensing signal Vo before the common voltage Vcom becomes high again.

Since the sensing data signal is changed based on the first reset voltage Vr1, the sensing data signal may always have a voltage range within a predetermined range, thereby easily determining whether or not the contact is made.

After the sensing signal processor 801 reads the sensing signal Vo, the second reset signal RST2 becomes the gate-on voltage Von to turn on the second reset transistor Qr2. Then, the second reset voltage Vr2 is applied to the sensing data line SL to charge the sensing data line SL. The second reset voltage Vr2 is maintained until the next first reset voltage Vr2 is applied to the sensing data line SL. The second reset voltage Vr2 and the common voltage Vcom form an electric field in the liquid crystal layer between the sensing data line SL and the common electrode 270, and the liquid crystal molecules therebetween are inclined in accordance with the generated electric field. Is determined. The amount of change in the sensing data signal varies depending on the inclination direction of the liquid crystal molecules. The amount of change in the sensing data signal may be increased by setting the second reset voltage Vr2 to an appropriate value.

The gate-on voltage Von of the first reset signal RST1 may be applied when the common voltage Vcom is at a low level. At this time, after the common voltage Vcom is changed to a high level, the gate-on voltage Von of the first reset signal RST1 may be applied to the sensing signal (Bon). Read Vo). In addition, the first reset signal RST1 may be synchronized with an image scan signal applied to the last image scan line G _n .

The second reset signal RST2 may be the gate-on voltage Von in the 1H section immediately after the sensing signal Vo is read, or may be the gate-on voltage Von in the 1H section thereafter.

The timing diagram shown in FIG. 8B is substantially the same as the timing diagram shown in FIG. 8A. However, referring to FIG. 8B, unlike FIG. 8A, the first reset signal RST1 becomes the gate-on voltage Von when the common voltage Vcom is at a low level. That is, the first reset voltage Vr1 may be applied when the common voltage Vcom is at a low level. In addition, the sensing signal processor 801 reads the sensing signal Vo within a 2H period after the first reset signal RST1 becomes the gate-off voltage Voff. At this time, the common voltage Vcom maintains a high level for 2H time so that the sense data signal has a stable value. In this way, the amplifier AP and the capacitor Cf can sufficiently charge the output current from the output transistor Qs, so that the level of the sense signal Vo can be changed to be larger.

The sensing signal processor 801 may read the sensing signal Vo beyond the 2H period after the first reset signal RST1 becomes the gate-off voltage Voff, and the common voltage Vcom correspondingly Do not change the level.

Next, the connection relationship between the sensing data line and the sensing data processor in the liquid crystal display according to the exemplary embodiment of the present invention will be described in detail with reference to FIG. 9.

9 is an example of an equivalent circuit diagram illustrating a connection relationship between a sensing data line and a sensing data processor in a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 9, the liquid crystal panel assembly 301 may include each sensing data line SY ₁ -SY _{N in} addition to the plurality of sensing data lines SY ₁ -SY _N , SX ₁ -SX _M , and a plurality of sensing units SU1. And a plurality of first and second reset transistors Qr1 and Qr2 and a plurality of output transistors Qs connected to SX ₁ -SX _M , and horizontal and vertical sensing data lines through corresponding output transistors Qs ( includes the _{SY 1 -SY N, SX 1 -SX} M) a plurality of horizontal and vertical output data lines _{(OY 1 -OY N, OX 1} -OX M) that are connected respectively to the.

The position where the sensing unit SU1 is disposed in the liquid crystal panel assembly 301 is substantially the same as that of the liquid crystal panel assembly 300 illustrated in FIG. 3. In addition, the arrangement relationship between the sensing data lines SY ₁ -SY _N and SX ₁ -SX _M connected to each sensing unit SU1 is substantially the same as that shown in FIG. 3. The sensing signal processor 801 is also substantially the same as the sensing signal processor 800 described above. In addition, the display area, the edge area and the exposed area of the liquid crystal panel assembly 301 are substantially the same as that of the liquid crystal panel assembly 300 shown in FIG. 5. The sensing signal processor 801 is included in a single chip mounted in the lower exposure area of the liquid crystal panel assembly 301. In addition, the single chip further includes a data driver 500 as described above, and has a terminal arrangement corresponding to the sensing signal processor 801 and the data driver 500 according to the liquid crystal panel assembly 301.

Hereinafter, a part different from the liquid crystal panel assembly 300 shown in FIG. 3 will be described in detail.

Referring to FIG. 9, the first reset transistor Qr1 connected to the vertical sensing data lines SX _{1 to} SX _M is disposed in an upper edge region of the liquid crystal panel assembly 301 and the second reset transistor Qr2. ) And the output transistor Qs are disposed in the lower edge region. The first reset transistor Qr1 connected to the horizontal sensing data line SY ₁ -SY _N is disposed in the left edge region of the liquid crystal panel assembly 301, and has a second reset transistor Qr2 and an output transistor Qs. ) Is located in the right edge area. However, if necessary, the second reset transistor Qr2 may be disposed in a region where the first reset transistor Qr1 is disposed. That is, the sizes of the output transistors Qs and the first and second reset transistors Qr1 and Qr2 may be different from each other. When the output transistors Qs and the first and second reset transistors Qr1 and Qr2 are appropriately distributed and disposed in the edge region of the liquid crystal panel assembly 301, The edge area can be minimized.

The vertical output data lines OX ₁ -OX _M extend from the lower edge area of the liquid crystal panel assembly 301 to the exposed area and are connected to the sensing signal processor 801, and the horizontal output data lines OY ₁ -OY _N are connected to each other. The liquid crystal panel assembly 301 extends downward from the right edge of the liquid crystal panel assembly 301 and passes through the exposed area to the sensing signal processor 801.

Image data lines (D ₁ -D _m) density and output data line _{(OY 1 -OY N, OX 1} -OX M) of, since the resolution of the liquid crystal display resolution of the detection unit (SU1) is different, as described previously The density is different. One vertical output data line OX ₁ -OX _M is positioned between the plurality of image data lines D ₁ -D _m , and the horizontal output data line OY ₁ -OY _{N is} connected to the liquid crystal panel assembly 301. They are arranged side by side on the right side, and the image data lines D ₁ -D _m are not disposed between them. Thus, when arranging the horizontal output data lines (OY ₁ -OY _N) the process for forming the horizontal output data lines (OY ₁ -OY _N) becomes simplified to reduce an output current distortion from the output transistor (Qs) . Corresponds to a single chip image data lines (D ₁ -D _m) and output data line _{(OY 1 -OY N, OX 1} -OX M) having such an arrangement corresponding to the liquid crystal panel assembly 301 according to this embodiment Has a terminal arrangement.

In the liquid crystal panel assembly 301 described above, the right and left sides may be interchanged, and the first and second reset transistors Qr1 and Qr2 and the output transistors connected to the horizontal sensing data lines SY _{1 to} SY _N may be used. Qs) and some of the horizontal output data lines OY ₁ -OY _N may change their position from left to right or from right to left.

According to the present invention, a more accurate sensing operation can be achieved by increasing the resolution of the sensing unit without increasing the number of sensing elements. As a result, the area of the driving unit can be reduced, and power consumption is reduced.

Claims (10)

Display, A plurality of sensing units formed on the display panel and outputting a sensing signal according to a contact with the display panel; A sensing signal processor configured to receive the sensing signal and process the signal to generate sensing data; A contact determination unit for calculating a position of a contact point by calculating the sensed data Including, The sensing unit neighbors each other and includes first, second, and third sensing units which output first, second, and third sensing signals, respectively. And the touch determination unit determines the contact point with respect to the display panel by comparing the first, second and third sensing signals. In claim 1, The liquid crystal display of which the value of the second sensing signal is greater than the values of the first and third sensing signals. In claim 2, If the value of the first sensing signal and the value of the third sensing signal are substantially the same, the contact point is the second sensing unit, If the value of the first sensing signal is greater than the value of the third sensing signal, the contact point is between the first sensing unit and the second sensing unit, And when the value of the third sensing signal is greater than the value of the first sensing signal, the contact point is between the second sensing unit and the third sensing unit. In claim 2, F1 = {F (n) -F (n-1)}-{F (n) -F (n + 1)}, provided that F (n-1), F (n) and F (n + 1) Are the values of the first, second and third sensing signals, respectively) If -S <F1 <S (where S = F (n) / 2) is satisfied, the contact point is the second sensing unit, If F1> S is satisfied, the contact point is between the second sensing unit and the third sensing unit, When F1 <-S is satisfied, the contact point is between the second sensing unit and the first sensing unit. Liquid crystal display. In claim 1, Further comprising a sensing data line formed on the display panel, The detection unit, A variable capacitor connected to the sensing data line and whose capacitance changes due to the pressure; A reference capacitor connected to the sense data line, and First and second reset transistors connected to the sensing data lines and supplying first and second reset voltages to the sensing data lines at different times, respectively. Containing Liquid crystal display. In claim 5, And a plurality of output transistors connected to the sensing data line and generating an output signal based on the sensing data signal flowing through the sensing data line and outputting the output signal to the sensing signal processor. In claim 6, The sensing signal processor includes a plurality of integrators for generating the sensing signal by integrating the output signal. In claim 7, The integrator includes an amplifier and a capacitor. In claim 5, And the first reset transistor applies the first reset voltage to the sense data line before the sense signal processor generates the sense signal. In claim 9, And the second reset transistor applies the second reset voltage to the sense data line after the sense signal processor generates the sense signal.

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