Touch screen display device and driving method of the same

A touch screen display device and a driving method of the same are provided. The touch screen display device includes a touch screen display panel including a plurality of first sensing lines that extend in a first direction, a plurality of second sensing lines that extend in a second direction and cross the first direction, and a plurality of touch sensing elements respectively arranged at areas where the first sensing lines and the second sensing lines cross each other; and a read-out unit that receives output signals of the respective first sensing lines and second sensing lines, reading at least one sensing position, and outputting one of the at least one read sensing positions as a touch position, wherein if the number of sensing positions of the current frame is equal to or greater than two, the read-out unit compares the at least two sensing positions of the current frame with a touch position of the previous frame, and outputs the sensing position that is closest to the touch position of the previous frame as a touch position of the current frame.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from and the benefit of Korean Patent Application No. 10-2008-0073557, filed on Jul. 28, 2008, which is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a touch screen display device, and more particularly, to a touch screen display device having improved reliability and a driving method of the same.

2. Discussion of the Background

A touch screen display device is a display device having a touch screen function and allowing a user to directly touch an arbitrary position by a finger on the touch screen display device to enter a desired operation command.

A display device having a touch screen function may be widely used because it is provided with an intuitive interface allowing a user to easily enter information. The display device may include a plurality of pixels for displaying images and a plurality of touch sensing elements for sensing a user's touched positions.

Gate signals and data signals may be applied to the respective pixels, and the respective touch sensing elements generate output signals according to the presence or absence of an external touch. Accordingly, the display device may require a gate driver and a data driver for applying gate signals and data signals, respectively, and a read-output unit for reading signals output from the respective touch sensing elements.

SUMMARY OF THE INVENTION

The present invention provides a touch screen display device having improved reliability.

The present invention also provides a driving method of a touch screen display device having improved reliability.

The present invention discloses a touch screen display device including a touch screen display panel, which includes a plurality of first sensing lines that extend in a first direction, a plurality of second sensing lines that extend in a second direction and cross the first direction, and a plurality of touch sensing elements respectively arranged at intersection areas where the first sensing lines and the second sensing lines cross each other, and a read-out unit that receives output signals of the respective first sensing lines and second sensing lines, reads at least one sensing position, and outputs one of the at least one read sensing positions as a touch position, wherein if the number of sensing positions of the current frame is equal to or greater than two, the read-out unit compares the at least two sensing positions of the current frame with a touch position of the previous frame, and outputs the sensing position that is closest to the touch position of the previous frame as a touch position of the current frame.

The present invention also discloses a method of driving a touch screen display device, which includes providing a touch screen display panel that includes a plurality of first sensing lines that extend in a first direction, a plurality of second sensing lines that extend in a second direction and cross the first direction, and a plurality of touch sensing elements respectively formed at intersection areas where the first sensing lines and the second sensing lines cross each other; receiving output signals of the respective first sensing lines and second sensing lines and reading at least one sensing position; and outputting one of the at least one read sensing positions as a touch position; wherein if the number of sensing positions of the current frame is equal to or greater than two, the at least two sensing positions of the current frame are compared with the touch position of the previous frame, and the sensing position that is closest to a touch position of the previous frame is output as a touch position of the current frame.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

A touch screen display device according to an exemplary embodiment of the present invention and a driving method of the touch screen display device will be described with reference toFIG. 1.FIG. 1is a block diagram showing a touch screen display device1according to an exemplary embodiment of the present invention and a driving method of the touch screen display device.

Referring toFIG. 1, the touch screen display device1includes a touch screen display panel300, a signal controller400, a gate driver600, a data driver500, and a read-out unit700.

The touch screen display panel300includes first sensing lines SLx1-SLxk (not shown) extending in a first direction, second sensing lines SLy1-SLyj (not shown) extending in a second direction that is substantially perpendicular to the first direction, and a plurality of touch sensing elements TS formed at areas where the first sensing lines SLx1-SLxk and the second sensing lines SLy1-SLyj cross each other.

In addition, the touch screen display panel300includes a plurality of gate lines GL1-GLk (not shown) extending in a direction substantially parallel to the first direction, a plurality of data lines DL1-DLj (not shown) extending in a direction substantially parallel to the second direction, and a plurality of pixels PX defined by the respective gate lines GL1-GLk and the respective data lines DL1-DLj in a matrix form.

The gate lines GL1-GLk receive respective gate signals G1-Gk from the gate driver600, and the data lines DL1-DLj receive respective image data voltages D1-Dj from the data driver500. The first and second sensing lines SLx1-SLxk and SLy1-SLyj supply output signals Vx1-Vxk and Vy1-Vyj to the read-out unit700, respectively.

FIG. 1shows an fth gate line GLf (f=1˜k), a gth data line DLg (g=1˜j), and a pixel PX defined at a crossing area of the fth gate line GLf and the gth data line DLg, as well as a fth first sensing line SLxf (f=1˜k), a gth second sensing line SLyg (g=1˜j), and a touch sensing element TS defined at a crossing area of the fth first sensing line SLxf and the gth second sensing line SLyg. The plurality of gate lines GL1-GLk, the plurality of data lines DL1-DLj, the plurality of pixels PX, the plurality of first sensing lines SLx1-SLxk, the plurality of second sensing lines SLy1-SLyj, and the plurality of touch sensing elements TS will be shown by way of examples.

Referring toFIG. 1, which shows an equivalent circuit diagram, a pixel PX includes a switching element Qp connected to the fth gate line GLf and the gth data line DLg, and a liquid crystal capacitor Clc and a storage capacitor Cst connected to the switching element Qp. The liquid crystal capacitor Clc may have a common voltage Vcom at its second end and the storage capacitor Cst may be connected to a ground terminal at its second end.

Referring toFIG. 1, a touch sensing element TS includes a first sensor electrode29extending from the first sensing line SLxf, a second sensor electrode63extending from the second sensing line SLyg, and a sensor spacer92connected to the first sensor electrode29and the second sensor electrode63in response to an external contact. Here, the sensor spacer92may have a common voltage Vcom. Accordingly, if the sensor spacer92comes into contact with the first sensor electrode29and the second sensor electrode63by an external stimulus, e.g., an external touch, the first sensing line SLxf and the second sensing line SLyg may have output signals supplied with a predetermined level of a common voltage Vcom.

The signal controller400receives first image signals R, G, and B and outputs second image signals IDAT corresponding to the received first image signals R, G, and B. In addition, the signal controller400receives external control signals Vsync, Hsync, Mclk, and DE and generates a data control signal CONT1and a gate control signal CONT2. Examples of the external control signals Vsync, Hsync, Mclk, and DE include a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a main clock signal Mclk, and a data enable signal DE. The gate control signal CONT2controls the operation of the gate driver600while the data control signal CONT1controls the operation of the data driver500.

The signal controller400also generates a touch sensing control signal CONT3, and supplies the same to a first sensor unit710and a second sensor unit720. Examples of the touch sensing control signal CONT3include a loading signal (not shown), and a shift clock signal (not shown).

The gate driver600, provided with the gate control signal CONT2from the signal controller400, applies the gate signals G1-Gk to the gate lines GL1-GLk. Here, the gate control signal CONT2for controlling the operation of the gate driver600includes a vertical synchronization start signal instructing start of the operation of the gate driver600, a gate clock signal controlling an output timing of the gate on signal, an output enable signal that determines the duration of the gate-on voltage Von, etc. The gate signals G1-Gk are composed of a combination of a gate-on voltage Von and a gate-off voltage Voff, which are generated from a gate on/off voltage generator (not shown).

The data driver500receives the data control signal CONT1from the signal controller400and applies the image signal voltage D1-Dj corresponding to the second image signal IDAT to the data lines DL1-DLj. Here, the data control signal CONT1includes signals for controlling the operation of the data driver500. The signals for controlling the operation of the data driver500include a horizontal synchronization start signal for starting the operation of the data driver500, an output enable signal for determining the output of an image data voltage D1-Dj, etc.

The read-out unit700may include a first sensor unit710, a second sensor unit720, and a touch position determination unit730. The first sensor unit710senses first active lines among the plurality of first sensing lines SLx1-SLxk, the first active lines corresponding to positions of external stimuli. The second sensor unit720senses second active lines among the plurality of second sensing lines SLy1-SLyj, the second active lines corresponding to positions of external stimuli. The touch position determination unit730determines a touch position TP based on the first and second active lines. The sensing positions sensed by the read-out unit700as touch positions are corresponding combinations of the first and second active lines.

The first sensor unit710receives output signals Vx1-Vxk of the respective first sensing lines SLx1-SLxk and recognizes the first active lines corresponding to the positions of external stimuli. The first sensor unit710recognizes at least one first active line and outputs a first read-out signal ROx. Although not shown, the first sensor unit710operates upon the receipt of a reference voltage Vref and a reset voltage Vrst, which are externally supplied.

Similarly, the second sensor unit720receives output signals Vy1-Vyj of the respective second sensing lines SLy1-SLyj and recognizes the second active lines corresponding to the positions of external stimuli. That is, the second sensor unit720recognizes at least one second active line and outputs a second read-out signal ROy. Although not shown, the second sensor unit720may operate upon the receipt of a reference voltage Vref and a reset voltage Vrst, which are externally supplied.

The first and second sensor units710and720may be implemented into a single chip together with the gate driver600and the data driver500. Further, the first and second sensor units710and720implemented into a single chip may be driven independent of the gate driver600and the data driver500.

The touch position determination unit730receives the first and the second read-out signals ROx and ROy, recognizes one or more sensing positions of the current frame using the first and second active lines, and outputs one of the recognized one or more sensing positions as a touch position TPn of the current frame. The touch position determination unit730will be described in more detail below.

The touch screen display panel300shown inFIG. 1will be described in greater detail with reference toFIG. 2,FIG. 3,FIG. 4, andFIG. 5.FIG. 2is a layout of a first substrate100included in a touch screen display panel300shown inFIG. 1,FIG. 3is a layout of a second substrate200included in the touch screen display panel300shown inFIG. 1,FIG. 4is a cross-sectional view of the touch screen display panel shown inFIG. 1, along line IIb-IIb′ inFIG. 2, andFIG. 5is a cross-sectional view showing a process of entering position information by touching a particular position on the touch screen display panel300shown inFIG. 4.

The touch screen display panel300includes a first substrate (100ofFIG. 4) having a plurality of gate lines GL1-GLk, a plurality of data lines DL1-DLj, a plurality of pixels PX, a plurality of first sensing lines SLx1-SLxk, and a plurality of second sensing lines SLy1-SLyj, a second substrate (200ofFIG. 4) facing the first substrate100and having a common electrode (90ofFIG. 4) and a sensor spacer (92ofFIG. 4), and a liquid crystal molecule layer (150ofFIG. 4) disposed between the first and second substrates100and200.

The first substrate100will first be described with reference toFIG. 2andFIG. 4. A gate electrode26in the form of a protrusion is formed on the gate line GLf disposed on an insulating substrate10in a first direction. A gate line end portion24is formed at an end of the gate line GLf to receive a gate signal (Gf ofFIG. 1) from the outside and transmit the received gate signal Gf to the gate line GLf.

In addition, a first sensing line SLxf is formed on the insulating substrate10. It is spaced apart from the gate line GLf and substantially parallel with the first direction. Further, a first sensor electrode29, which has an expanded width, extends from the first sensing line SLxf in the form of a protrusion. The first sensor electrode29comprises one terminal of a touch sensing element (TS ofFIG. 1) and is electrically connected to the first sensor pad84through a contact hole72. When an external pressure is applied to the panel in the vicinity of the first sensor pad84, the first sensor electrode29is electrically connected to the common electrode90on the sensor spacer92to provide position information corresponding to the position at which the external pressure is applied.

A gate insulating layer30is formed on the gate line GLf, the gate line end portion24, the gate electrode26, the first sensing line SLxf and the first sensor electrode29. An active layer40is formed on the gate insulating layer30, and ohmic contact layers55and56are formed on the active layer40.

A data line DLg and a drain electrode66are formed on the ohmic contact layers55and56and the gate insulating layer30. The data line DLg extends in the second direction in the figures to cross the gate line GLf. A source electrode65extends over the active layer40in the second direction as a branch of the data line DLg. A data line end portion68is formed at one end of the data line DLg to receive an image data voltage (Dg ofFIG. 1) from the outside and to transmit the same to the data line DLg. The drain electrode66is spaced apart from the source electrode65and is located on the active layer40so as to face the source electrode65at the opposite side of the gate electrode26. The drain electrode66comprises a drain electrode extension67that has a wide area where a contact hole76is located.

The second sensor line SLyg may be formed on the gate insulating layer30. The second sensor line SLyg is separate from the data line DLg and is substantially parallel with the second direction. The second sensor electrode63protrudes from the second sensor line SLyg and has an extended width. Here, the second sensor electrode63functions as a terminal of the touch sensing element (TS ofFIG. 1) and is connected to the second sensor pad85through the contact hole73. Upon receiving an external pressure, the second sensor electrode63is connected to the common electrode90on the sensor spacer92, and information corresponding to the location at which the external pressure is applied to the display is provided.

The source electrode65has at least a portion overlapping the active layer40, and the drain electrode66faces the source electrode65about the gate electrode26and has at least a portion overlapping the active layer40. Here, the ohmic contact layers55and56are disposed between the active layer40and the source electrode65, and between the active layer40and the drain electrode66, to reduce the contact resistance therebetween.

A passivation layer70, which is made of an insulating film, is formed on the data line DLg, the source electrode65, the drain electrode66, the data line expansion67, the data line end portion68, the second sensor electrode63, the second sensing lines SLyg, and the exposed active layer40.

Contact holes73,76, and78, which expose the second sensor electrode63, the drain electrode66, and the data line end portion68, respectively, are formed in the passivation layer70. Contact holes72and74, which expose the first sensor electrode29and the gate line end portion24, respectively, are formed in the passivation layer70and the gate insulating layer30. A pixel electrode82, which is electrically connected to the drain electrode66via the contact hole76, is formed on the passivation layer70according to a pixel shape. In addition, a gate line pad86and a data line pad88are formed on the passivation layer70such that they are electrically connected to the gate line end portion24and the data line end portion68through the contact holes74and78, respectively. Further, the first sensor pad84and the second sensor pad85are formed on the passivation layer70such that they are electrically connected to the first sensor electrode29and the second sensor electrode63through the contact holes72and73, respectively.

Next, the second substrate200will be described with reference toFIG. 3andFIG. 4. A black matrix94for blocking light leakage, and a color filter98disposed on an exemplary pixel is formed on an insulating substrate96. A sensor spacer92is formed on the color filter98. In the exemplary embodiment shown, the sensor spacer92may be formed as part of the color filter98. The common electrode90, which may be made of a transparent conductive material, is formed on the black matrix94, the color filter98, and the sensor spacer92. In addition, a support spacer93is formed on the common electrode90. The support spacer93maintains a specific gap between the first substrate100and the second substrate200, thereby forming a predetermined cell gap.

Next, a process of entering position information by touching a particular position on the touch screen display panel300will be described with reference toFIG. 4andFIG. 5.

In an initial state where there is no external pressure applied, that is, in the absence of an electric field, the sensor spacer92is separated from the first substrate100. However, upon receiving an external pressure, the common electrode90provided on the sensor spacer92contacts the first sensor pad84and the second sensor pad85, thereby connecting the common electrode90, the first sensor pad84, and the second sensor pad85. That is to say, as shown inFIG. 5, if a user touches a particular position with a finger, a pen170, or the like, the common electrode90on the sensor spacer92is connected with the first and the second sensor pads84and85on the first substrate100at the particular position, and a position information signal corresponding to the particular position is generated.

A touch screen display device according to an exemplary embodiment of the present invention and a driving method of the same will now be described in detail with reference toFIG. 6,FIG. 7,FIG. 8A, andFIG. 8B.FIG. 6is a touch position determination unit included in the touch screen display panel shown inFIG. 1,FIG. 7is a block diagram of a sensing position recognition unit included in the touch position determination unit shown inFIG. 6, andFIG. 8AandFIG. 8Bshow an actual touch operation and final output result in a touch screen display device according to an exemplary embodiment of the present invention.

The touch position determination unit730includes a sensing position recognition unit740recognizing one or more sensing positions of the current frame using the first and second active lines, and a filtering unit750filtering one sensing position among the one or more sensing positions of the current frame, the one sensing position that is closest to a touch position TPn-1of the previous frame as the touch position TPn of the current frame.

The sensing position recognition unit740may include a first filtering unit741, a position value designation unit742, and a counter743.

The position value designation unit742may designate at least one first position value PVx corresponding to the first active line and at least one second position value PVy corresponding to the second active line. The first and second position values PVx and PVy will be described in more detail below with reference toFIG. 7. The sensing position recognition unit740recognizes one or more sensing positions designated by the position value designation unit742based on combinations of the first and second position values PVx and PVy.

The counter743counts numbers of the at least one first and second position values PVx and PVy, respectively, and transmits the counted numbers to the filtering unit750.

A method of recognizing the sensing positions will now be described in more detail with reference toFIG. 7. For convenience of explanation, the invention will be described with regard to first sensing lines SLx1-SLxk by way of example. Since the invention may be applied to the second sensing lines SLy1-SLyj in substantially the same manner as the first sensing lines SLx1-SLxk, an explanation thereof will be not be given.

Sensing line data indicating whether or not there is an external stimulus sensed from a plurality of first sensing lines SLx1-SLxk are listed in the upper part ofFIG. 7. If there is an external stimulus sensed from the first sensing lines, the sensing line data has a first level, e.g., a voltage level of “1,” while if there is no external stimulus sensed from the first sensing lines, the sensing line data has a second level, e.g., a voltage level of “0.” Accordingly, if a voltage level is “1,” the corresponding sensing line is an active line.

Data listed under the sensing line data are position values corresponding to the respective sensing lines. InFIG. 7, natural numbers gradually increasing according to the order of sensing lines placed are designated as the position values, but are not limited thereto.

The output signal corresponding to the sensing line data is shown in the middle part ofFIG. 7. As described above, since the sensing line data is the signal indicating whether there is an external stimulus sensed from the plurality of first sensing lines SLx1-SLxk, the sensing line data corresponds to the first read-out signal ROx. If the sensing line data is in a first level, the output signal has a high level, and while the sensing line data is in a second level, the output signal has a low level.

As shown inFIG. 7, the active lines may be consecutively generated. That is to say, external stimuli may be simultaneously applied to neighboring sensing lines among multiple sensing lines. In the present example, neighboring sensing lines corresponding to position values 3, 4, and 5 may be active lines. Here, a representative position value is designated for the neighboring, consecutive active lines that may be associated with one sensing position.

The read-out unit700may designate the number of reference lines for first and second neighboring active lines. In addition, if numbers of first and second neighboring active lines are greater than the number of reference lines, the read-out unit700may designate the first or second position value of first or second neighboring active lines as a first or second representative position value. On the other hand, if the numbers of first and second neighboring active lines are equal to or smaller than the number of reference lines, the first or second neighboring active lines may be ignored.

The first and second representative position values may be designated based on two position values corresponding to, among the plurality of first and second sensing lines, sensing lines each having an output signal making a transition from second level to first level or from first level to second level. For example, as shown inFIG. 7, the first representative position value may be a mean value 4.5 ((3+6)/2) of position values 3 and 6, where position value 3 corresponds to the sensing line having an output signal transitioning from second level “0” to first level “1,” and position value 6 corresponds to the sensing line having an output signal transitioning from first level “1” to second level “0.” The second representative position value may be a mean value 12 ((11+13)/2) of position values 11 and 13, where position value 11 corresponds to the sensing line having an output signal making a transition from second level “0” to first level “1,” and position value 13 corresponds to the sensing line having an output signal transitioning from first level “1” back to second level “0.”

The lower part ofFIG. 7indicates data output from the counter743. The counter743performs counting operations when transitions are made from high level to low level. That is, the number of position values or representative position values can be counted based on the output signal making level transitions, thereby counting the number of sensing positions.

Referring again toFIG. 6, a filtering unit750includes a filtering determination unit751, a touch position tracking unit752, and a touch position output unit753.

The filtering determination unit751receives first and second position values PVx and PVy and numbers PNx and PNy of first and second position values, respectively, and determines whether there is any one value among the first and second position values PVx and PVy that may be ignored. That is to say, the filtering determination unit751determines whether at least one of the numbers of the first and second position values PNx and PNy is equal to or greater than 2 (two). If both of the numbers PNx and PNy of the first and second position values are equal to 1 (one), the first and second position values PVx and PVy are output to the touch position output unit753as touch positions TPn of the current frame.

If the at least one of the numbers PNx and PNy of the first and second position values is equal to or greater than 2, the touch position tracking unit752transmits one of the two or more sensing positions corresponding to the first and second position values to the touch position output unit753. If the number of first position values PVx corresponding to the two or more sensing positions is equal to or greater than 2, the touch position tracking unit752compares distances between the two or more first position values PVx and first position values of the touch position of the previous frame, to output the sensing position having a smaller distance to the touch position output unit753. If the number of second position values PVy for two or more sensing positions is equal to or greater than 2, the touch position tracking unit752compares distances between the two or more second position values and second position values of the touch position of the previous frame, to output the sensing position having a smaller distance as the touch position TPn of the current frame.

The touch position output unit753may output one sensing position transmitted from the touch position tracking unit752or the filtering determination unit751as the touch position TPn of the current frame.

The touch position determination unit730may further include a touch signal generator760. The touch signal generator760, which is enabled responsive to the generated touch position TPn of the current frame, generates a touch signal TE_INT indicating that an external stimulus is applied to the touch screen display panel300. The touch signal TE_INT may be transmitted to an application (not shown) connected to the touch screen display panel300. Alternatively, data corresponding to the touch signal TE_INT may be received from the application.

FIG. 8AandFIG. 8Bshow an actual touch operation and final output result in a touch screen display device according to an exemplary embodiment of the present invention.

In a touch display panel in which a touch is applied in a direction from the right upper side to the left lower side, as shown inFIG. 8A, the line “a” indicates an operation line that has been actually touched, the line “b” indicates an operation line to be touched in a subsequent frame, and the line “c” indicates an operation line that has not been touched but is recognized to have been touched. In the current frame, the lines a, b, and c may contain a position A recognized as the touch position TPn-1of the previous frame, a position B to be recognized to have been sensed by an actual touch in a subsequent frame, and a position C that has not been touched but is recognized to have been touched.

Here, the touch screen display device according to an exemplary embodiment of the present invention compares a distance d1between the positions A and B with a distance d2between the positions A and C, and recognizes the position that is closer to the position A as the touch position TPn of the current frame. The same procedure is repeated on the subsequent frames, and a simulated output line “p” of the actual touch line is obtained, as shown inFIG. 8B.

As described above, in a case where two or more sensing positions are recognized in each frame, the touch position TPn of the current frame can be determined by comparing distances between each of the respective sensing positions and the touch position TPn-1of the previous frame. Therefore, the sensing position that has not actually been touched but is recognized to have been touched is left out of consideration as the touch position, thereby providing for a touch screen display device having improved reliability.

Hereinafter, a touch screen display device according to another exemplary embodiment of the present invention and a driving method of the same will be described with reference toFIG. 9.FIG. 9is a block diagram of shielding unit755included in a filtering unit750_1of a touch screen display device according to another exemplary embodiment of the present invention.

The touch screen display device according to another exemplary embodiment of the present invention is different from the touch screen display device according to the previous exemplary embodiment in that if a distance between two or more sensing positions is smaller than a reference distance Pr, the two or more sensing positions are ignored.

Referring toFIG. 9, the shielding unit755included in the touch screen display device compares a distance between two or more sensing positions with the reference distance Pr, and if the distance between the two or more sensing positions is smaller than the reference distance Pr, the two or more sensing positions are ignored, thereby providing for a touch screen display device having improved reliability.