KR20160094570A - Method For Driving Of Touch Display Device - Google Patents

Abstract

The present invention relates to a driving method of a touch display device, which can prevent the occurrence of a light leakage caused by a reference voltage applied to a touch driving electrode and a touch sensing electrode. According to an embodiment of the present invention, the driving method of the touch display device includes the steps of: applying a first voltage to an inner shield electrode during a first frame period; and applying a reference voltage to a plurality of touch driving electrodes and a plurality of touch sensing electrodes during a touch period of the first frame period. Herein, the reference voltage is set such that a difference value between the reference voltage and the first voltage is less than a driving voltage of a liquid crystal.

Description

[0001] The present invention relates to a driving method of a touch display device,

The present invention relates to a method of driving a touch display device capable of preventing light leakage due to a reference voltage applied to a touch driving electrode and a touch sensing electrode.

A touch panel capable of inputting information directly to a screen by using a finger or a pen in place of a conventional input device such as a mouse or a keyboard has been applied as an input device of a liquid crystal display device. The application of the touch panel is expanding because it is easy for anyone to operate it.

The touch panel can be divided into a resistance type, a capacitance type, and an infrared ray detection according to a touch sensing method. Recently, a capacitance type having advantages in convenience of manufacturing method and sensing sensitivity has been attracting attention. The capacitance type touch panel is divided into a mutual capacitance type and a self capacitance type.

2. Description of the Related Art In recent years, in the application of a touch screen to a liquid crystal display device, an in-cell touch method has been developed in which a capacitive touch sensor is embedded in a liquid crystal panel for slimming. In the following description, the touch display panel means that the touch sensor is incorporated in the liquid crystal panel.

FIG. 1 is a view showing a conventional touch display panel, and FIG. 2 is a view schematically showing a planar structure of a touch driving electrode (Tx electrode) and a touch sensing electrode (Rx electrode) of a touch display panel according to the related art . In FIG. 2, a touch driving electrode (Tx electrode) and a touch sensing electrode (Rx electrode) are arranged in a mutual capacitance manner.

1 and 2, a conventional touch display panel includes a TFT array substrate 1, a color filter array substrate 2, a liquid crystal layer 3 interposed between the two substrates 1 and 2, And a polarizing film (not shown).

A TFT (thin film transistor) is disposed as a switching element in each pixel arranged on the TFT array substrate 1, and a pixel electrode 12 and a common electrode 10 are arranged. The common electrode 10 is used as a touch electrode as well as a display.

A common electrode 10 is patterned in units of a plurality of pixels to form a plurality of touch driving electrodes 12 and a plurality of touch sensing electrodes 14 in a mutual capacitance manner. A plurality of touch sensing electrodes (14, Rx electrodes) are arranged in a longitudinal direction in the form of a line. The plurality of touch driving electrodes 12 are connected to each other in the horizontal direction by using contact holes with the touch sensing electrode 14 therebetween. Each of the plurality of touch driving electrodes 12 and the plurality of touch sensing electrodes 14 is connected to a touch driver (not shown) through a conductive line (not shown).

The conventional in-cell touch display device performs display driving and touch driving in a time division manner by separating one frame period into a display period and a touch period.

In the display period, a data voltage is supplied to the pixel electrode, and a common voltage Vcom is supplied to the touch driving electrode 12 and the touch sensing electrode 14 to display an image. In the touch period, a touch driving signal is supplied to each touch driving electrode 12, and then the capacitance of each touch sensing electrode 14 is sensed to sense touch presence or touch position.

The mutual capacitance type touch driving electrode 12 and the touch sensing electrode 14 are spaced apart from each other so that the data lines DL, the touch driving electrodes 12, and the data lines DL, And the touch sensing electrode 14 in the fringe field, thereby generating light leakage.

An inner shield line 16 is disposed between the touch driving electrode 12 and the touch sensing electrode 14 so as to cover the data line DL in order to prevent parasitic capacitance and light leakage.

3 is a view for explaining a problem that light leakage occurs due to a touch driving signal applied to a touch driving electrode in a touch period.

Referring to FIG. 3, a common voltage Vcom is applied to the inner shield electrode 16, and a touch driving signal having a reference voltage Vref is applied to the touch driving electrode for a half period of one frame.

A voltage difference Vd1 is generated between the common voltage Vcom applied to the inner shield electrode 16 and the reference voltage Vref when the reference voltage Vref of the touch driver falls to the ground GND in the touch period, .

The touch sensing electrode 14 and the inner shield electrode 14 are driven by the reference voltage Vref of the touch driving signal supplied to the touch driving electrode 12 in the touch period even if the inner shield electrode 16 is disposed. There is a problem that a light leakage occurs due to a fringe field between the light emitting elements 16 and 16.

That is, when the difference between the reference voltage Vref and the common voltage Vcom supplied to the touch driving electrode and the touch sensing electrode is larger than the operating voltage of the liquid crystal, the liquid crystal behaves to generate light leakage.

Here, when the overlay between the respective layers and the adhesion shift of the TFT array substrate and the color filter array substrate occur, the difference between the common voltage Vcom applied to the inner shield electrode 16 and the reference voltage Vref of the touch driver The light leakage caused by the voltage Vd1 becomes stronger.

[Integrated touch screen] (US Patent No. 7859521)

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of driving a touch display device capable of preventing light leakage caused by a reference voltage applied to a touch driving electrode in a touch period.

SUMMARY OF THE INVENTION The present invention provides a method of driving a touch display device capable of preventing light leakage due to a reference voltage applied to a touch sensing electrode during a touch period.

Other features and advantages of the invention will be set forth in the description which follows, or may be obvious to those skilled in the art from the description and the claims.

A method of driving a touch display device according to an embodiment of the present invention applies a first voltage to an inner shield electrode during one frame period. A reference voltage is applied to the plurality of touch driving electrodes and the plurality of touch sensing electrodes in the touch period during the one frame period. Here, the reference voltage is set so that the difference between the reference voltage and the first voltage is smaller than the operating voltage of the liquid crystal.

A method of driving a touch display device according to an embodiment of the present invention sets the first voltage to a common voltage.

A method of driving a touch display device according to an embodiment of the present invention generates a touch driving signal for maintaining the reference voltage after a high voltage pulse and supplies the touch driving signal to the plurality of touch driving electrodes. Here, the reference voltage is maintained for 1/2 of one frame period.

A method of driving a touch display device according to an embodiment of the present invention includes generating a touch driving signal such that the touch driving signal is lowered to a ground voltage for a first period before and after a high voltage pulse and then raised to an original reference voltage, And applies the touch driving signal.

The driving method of the touch display device according to the embodiment of the present invention can prevent the light leakage by controlling the voltage of the touch driving signal applied to the touch driving electrode.

The driving method of the touch display device according to the embodiment of the present invention can prevent the generation of light leakage by adjusting the reference voltage applied to the touch driving electrode in the touch period.

The driving method of the touch display device according to the embodiment of the present invention can prevent the generation of light leakage by adjusting the reference voltage applied to the touch sensing electrode in the touch period.

In addition, other features and advantages of the present invention may be newly understood through embodiments of the present invention.

1 is a view illustrating a conventional touch display panel.
2 is a diagram schematically showing a planar structure of a touch driving electrode (Tx electrode) and a touch sensing electrode (Rx electrode) of a touch display panel according to a related art.
3 is a view for explaining a problem that light leakage occurs due to a touch driving signal applied to a touch driving electrode in a touch period.
4 is a view schematically showing a touch display device according to an embodiment of the present invention.
5 is a diagram showing a planar structure of a touch driving electrode (Tx electrode) and a touch sensing electrode (Rx electrode) of a touch display device according to an embodiment of the present invention.
6 is a diagram illustrating a method of driving a touch display device according to a first embodiment of the present invention.
7 is a diagram illustrating a method of driving a touch display device according to a second embodiment of the present invention.

Like reference numerals throughout the specification denote substantially identical components. In the following description, detailed descriptions of configurations and functions known in the technical field of the present invention and those not related to the core configuration of the present invention can be omitted. The meaning of the terms described herein should be understood as follows.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. To fully disclose the scope of the invention to a person skilled in the art, and the invention is only defined by the scope of the claims.

It should be noted that, in the specification of the present invention, the same reference numerals as in the drawings denote the same elements, but they are numbered as much as possible even if they are shown in different drawings.

The shapes, sizes, ratios, angles, numbers, and the like disclosed in the drawings for describing the embodiments of the present invention are illustrative, and thus the present invention is not limited thereto. Like reference numerals refer to like elements throughout the specification. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. In the case where the word 'includes', 'having', 'done', etc. are used in this specification, other parts can be added unless '~ only' is used. Unless the context clearly dictates otherwise, including the plural unless the context clearly dictates otherwise.

In interpreting the constituent elements, it is construed to include the error range even if there is no separate description.

In the case of a description of the positional relationship, for example, if the positional relationship between two parts is described as 'on', 'on top', 'under', and 'next to' Or " direct " is not used, one or more other portions may be located between the two portions.

In the case of a description of a temporal relationship, for example, if the temporal relationship is described by 'after', 'after', 'after', 'before', etc., May not be continuous unless they are not used.

The term " at least one " should be understood to include all possible combinations from one or more related items. For example, the meaning of 'at least one of the first item, the second item and the third item' means not only the first item, the second item or the third item, but also the second item, the second item and the third item, Means any combination of items that can be presented from more than one.

The first, second, etc. are used to describe various components, but these components are not limited by these terms. These terms are used only to distinguish one component from another. Therefore, the first component mentioned below may be the second component within the technical spirit of the present invention.

It is to be understood that each of the features of the various embodiments of the present invention may be combined or combined with each other, partially or wholly, technically various interlocking and driving, and that the embodiments may be practiced independently of each other, It is possible.

The liquid crystal display device has been developed in various ways such as TN (Twisted Nematic) mode, VA (Vertical Alignment) mode, IPS (In Plane Switching) mode and FFS (Fringe Field Switching) mode according to a method of adjusting the arrangement of liquid crystal layers.

In the TN mode and the VA mode, a pixel electrode is formed on a lower substrate and a common electrode is formed on an upper substrate (color filter array substrate) to control the alignment of the liquid crystal layer through a vertical electric field.

In the IPS mode and the FFS mode, a pixel electrode and a common electrode are disposed on a lower substrate, and the arrangement of the liquid crystal layer is adjusted by an electric field between the pixel electrode and the common electrode.

In the IPS mode, the pixel electrode and the common electrode are alternately arranged in parallel to each other to generate a horizontal electric field between the two electrodes to adjust the alignment of the liquid crystal layer.

In the FFS mode, the pixel electrode and the common electrode are spaced apart with an insulating layer therebetween. At this time, one electrode is formed in a plate shape or a pattern and the other electrode is formed in a finger shape, and the arrangement of the liquid crystal layer is controlled through a fringe field generated between the electrodes Method.

The touch panel according to the embodiment of the present invention can be applied to both the vertical electric field method (TN mode, VA mode) and the horizontal electric field method (IPS mode, FFS mode) without limitation of mode, Mode or the FFS mode is applied as an example.

Hereinafter, a method of driving a touch display device according to an embodiment of the present invention will be described with reference to the accompanying drawings.

4 is a view schematically showing a touch display device according to an embodiment of the present invention.

4, a touch display device according to an embodiment of the present invention includes a touch display panel 100, a gate driver 200, a data driver 300, a touch driver 400, a timing controller 500, . In FIG. 4, the backlight unit is not shown.

The gate driver 200, the data driver 300, the touch driver 400, and the timing controller 500 may be implemented as a whole or a part of the components in a chip on glass (COG) or a chip on flexible printed circuit (COF) As shown in FIG.

The touch display panel 100 includes a TFT array substrate in which a plurality of pixels P are arranged in a matrix and in which a TFT, a pixel electrode, a common electrode, and a storage capacitor Cst are arranged, and an RGB color filter And a liquid crystal layer interposed between the two substrates.

Here, the plurality of pixels P are defined by a plurality of data lines and a plurality of gate lines crossing each other. And a TFT and a storage capacitor (Cst) are disposed for each region where the data line and the gate line cross each other.

5 is a diagram showing a planar structure of a touch driving electrode (Tx electrode) and a touch sensing electrode (Rx electrode) of a touch display device according to an embodiment of the present invention.

Referring to FIG. 5, pixel electrodes (not shown) are disposed in each pixel of the TFT array substrate, and the common electrode 110 is disposed to correspond to each pixel. The pixel electrode and the common electrode 110 are formed of a transparent conductive material such as ITO (Indium Tin Oxide).

The common electrode 110 is used as a touch electrode as well as a display. To this end, the common electrode 110 is patterned to form a plurality of touch driving electrodes 112, a Tx electrode, and a touch sensing electrode 114 (Rx electrode).

The plurality of touch sensing electrodes 114 are arranged in a longitudinal direction in the form of a line. The plurality of touch driving electrodes 112 are disposed with the touch sensing electrode 114 interposed therebetween, and the touch driving electrodes 112 are connected in the horizontal direction by using the contact holes and the bridge pattern.

Each of the plurality of touch driving electrodes 112 is connected to the touch driver 400 through a plurality of first touch signal lines 120. Each of the plurality of touch sensing electrodes 114 is connected to the touch driver 400 through a plurality of second touch signal lines 130.

An inner shield electrode 116 is disposed between the touch driving electrode 112 and the touch sensing electrode 114 to prevent parasitic capacitance and light leakage.

One frame period is divided into a display period and a touch period, and display driving and touch driving are performed in a time division manner. In the display period, a data voltage is supplied to the pixel electrode, and a common voltage Vcom is supplied to the touch driving electrode 112 and the touch sensing electrode 114 to display an image. During the touch period, a touch driving signal is supplied to each of the touch driving electrodes 112, and then the capacitance of each touch sensing electrode 114 is sensed to sense touch presence or touch position.

Here, the first voltage may be applied to the inner shield electrode 116 during the display period and the touch period. At this time, the first voltage may be set to a common voltage or an arbitrary voltage.

Referring again to FIG. 4, the timing controller 500 controls driving of the gate driver 200, the data driver 300, and the touch driver 400.

The timing controller 500 receives the timing signal TS and the RGB video signal. The timing controller 500 converts the input RGB video signal into digital RGB video data using a timing signal TS input from the outside and supplies the RBG video data to the data driver 300. At this time, the timing signal TS includes a vertical synchronization signal V-sync, a horizontal synchronization signal H-sync, and a clock signal CLK.

The timing controller 500 also generates a gate control signal (GCS: Gate Control Signal) for controlling the gate driver 200 using the timing signal TS and supplies it to the gate driver 200. The gate control signal GCS may include a gate start pulse (GSP), a gate shift clock (GSC), and a gate output enable (GOE).

The timing controller 500 also generates a data control signal (DCS) for controlling the data driver 300 using the timing signal TS and supplies the data control signal DCS to the data driver. The data control signal DCS includes a source start pulse (SSP), a source sampling clock (SSC), a source output enable (SOE) and a polarity control signal (POL) . ≪ / RTI >

In addition, the timing controller 500 supplies the touch driver 400 with a synchronization signal of a display period and a touch period so that the touch driver 400 can be driven in a touch period.

The gate driver 200 generates a gate driving signal for driving the TFT formed in each of the plurality of pixels based on the gate control signal GCS from the timing controller 500. [ The gate driver 200 may be formed of a separate chip or may be embedded in a TFT array substrate of a touch display panel by a GIP (gate in panel) method.

The gate driver 200 sequentially supplies gate driving signals to a plurality of gate lines formed in the liquid crystal panel in a display period in one frame period. The TFT formed on each pixel is turned on by the gate driving signal.

The data driver 300 converts the digital RGB image data supplied from the timing controller 500 into an analog image signal, that is, an RGB data voltage. Based on the data control signal DCS from the timing controller 500, the data voltage is supplied to the plurality of data lines at the time when the TFT of each pixel is turned on in accordance with the gate driving signal.

The common voltage Vcom is supplied to the touch driving electrode 112 and the touch sensing electrode 144 together with the supply of the data voltage so that an image is displayed. The common voltage Vcom may be generated in the data driver 300 and supplied to the plurality of touch driving electrodes 112 and the plurality of touch sensing electrodes 114. As another example, the common voltage Vcom may be generated in the touch driver 400 and supplied to the plurality of touch driving electrodes 112 and the plurality of touch sensing electrodes 114.

The touch driver 400 supplies a touch driving signal to the plurality of touch driving electrodes 112 in the touch period based on the synchronizing signal supplied from the timing controller 500. The reference voltage Vref for touch sensing is supplied to the plurality of touch sensing electrodes 114.

The touch driving signal applied to the touch driving electrode 112 can be generated in various forms such as a square wave type pulse, a sine wave, and a triangle wave. Thereafter, the electrostatic capacitance formed on each of the plurality of touch sensing electrodes 114 is sensed. The presence or absence of a touch and the touch position are sensed based on a change in the amount of charge of each touch sensing electrode 114.

6 is a diagram illustrating a method of driving a touch display device according to a first embodiment of the present invention.

6, when a common voltage is supplied to the inner shield electrode, the difference voltage Vd2 between the reference voltage Vref_tx of the touch driving electrode and the reference voltage Vref_rx of the touch driving electrode and the common voltage is equal to the difference When the voltage is over, light leakage occurs.

In order to prevent the inner shield electrode and the fringe field from occurring due to the reference voltage Vref applied to the touch driving electrode and the touch sensing electrode in the touch period during one frame period, Adjust the voltage (Vref).

Here, a reference voltage is supplied to the touch driving electrode and the touch sensing electrode during the touch period, thereby adjusting the reference voltage Vref_tx of the touch driving electrode and the reference voltage Vref_rx of the touch driving electrode.

Specifically, the first voltage is applied to the inner shield electrode during one frame period, and the reference voltage (Vref_tx) is applied to the plurality of touch driving electrodes in the touch period during the one frame period. The reference voltage Vref_tx of the plurality of touch driving electrodes is set so that the reference voltage Vref_tx of the plurality of touch driving electrodes and the difference value Vd2 of the first voltage are smaller than the operating voltage of the liquid crystal.

Here, the common electrode may be supplied with the first voltage to the inner shield electrode.

In addition, the first voltage is applied to the inner shield electrode during the frame period, and the reference voltage (Vref_rx) is applied to the plurality of touch sensing electrodes in the touch period during the one frame period. At this time, the reference voltage Vref_rx of the plurality of touch sensing electrodes is set so that the reference voltage Vref_rx of the plurality of touch sensing electrodes and the difference value Vd2 of the first voltage are smaller than the operation voltage of the liquid crystal.

Here, the common electrode may be supplied with the first voltage to the inner shield electrode.

Generates a touch driving signal for maintaining the reference voltage after the high voltage pulse, and supplies the generated touch driving signal to the plurality of touch driving electrodes. At this time, a touch driving signal is generated to maintain the reference voltage for 1/2 period of one frame period, and a touch driving signal is applied to the plurality of touch driving electrodes in a touch period.

However, the present invention is not limited to this, and it is also possible to generate the touch driving signal so as to maintain the reference voltage within 1/2 period of one frame period. Further, the touch driving signal may be generated so as to maintain the reference voltage for 1/2 period or more of one frame period.

As a result, the reference voltage of the touch driver 400 is set so that the difference (Vd2) between the reference voltage output from the touch driver 400 and the first voltage (common voltage) supplied to the inner shield electrode is smaller than the operating voltage of the liquid crystal If set, light leakage can be prevented.

In the general touch driver, the reference voltage is set to ground (GND) or 3.3V. In the present invention, the reference voltage of the touch driver is set to a higher voltage.

Here, since the operating voltage varies depending on the type of the liquid crystal, the reference voltage of the touch driver is set based on the operating voltage of the liquid crystal. That is, the reference voltage of the touch driver is set so that the difference (Vd2) between the reference voltage and the common voltage of the touch driver is smaller than the operating voltage of the liquid crystal.

The driving method of the touch display device according to the first embodiment of the present invention described with reference to FIG. 6 can prevent the generation of light leakage by adjusting the reference voltage applied to the touch driving electrode and the touch sensing electrode in the touch period.

7 is a diagram illustrating a method of driving a touch display device according to a second embodiment of the present invention.

In order to enhance the touch sensing performance, the touch driving signals supplied to the plurality of touch driving electrodes can be adjusted. First, the reference voltage Vref of the touch driver is set so that the difference (Vd2) between the reference voltage and the common voltage of the touch driver is smaller than the operation voltage of the liquid crystal, as described with reference to Fig.

In order to enhance the touch sensing performance, the touch driving signal is generated so as to return to the ground (GND) voltage for a short time (T1) before and after the high voltage pulse of the touch driving signal, and then return to the original reference voltage again.

Specifically, after the reference voltage is lowered to the ground (GND) voltage for a short time T1, a high voltage pulse is output. (GND) voltage for a short time (T1) after the output of the high voltage pulse, and then generates the touch drive signal to return to the original reference voltage again.

As described above, if the touch driving signal is lowered to the ground (GND) voltage for a short time (T1) before and after the high voltage pulse, the amplitude value of the touch driving signal becomes large and the touch sensing performance can be enhanced.

Here, since the voltage is reduced to the ground (GND) voltage only for a short time T1, a fringe field is not formed to operate the liquid crystal. Accordingly, it is possible to improve the touch sensing performance while preventing light leakage.

The method of driving the touch display device according to the second embodiment of the present invention described with reference to FIG. 7 can prevent the generation of light leakage by adjusting the reference voltage applied to the touch driving electrode and the touch sensing electrode in the touch period.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

100: Touch display panel
112: touch driving electrode
114: Touch sensing electrode
116: Inner shield electrode
120: first touch signal line
130: second touch signal line
200: gate driver
300: data driver
400: Touch driver
500: Timing controller

Claims (4)

A first voltage is applied to the inner shield electrode during one frame period,
A reference voltage is applied to a plurality of touch driving electrodes and a plurality of touch sensing electrodes in a touch period during the one frame period,
Wherein the reference voltage is set so that a difference between the reference voltage and the first voltage is smaller than an operation voltage of the liquid crystal. The method according to claim 1,
And sets the first voltage to a common voltage. 3. The method of claim 2,
Generating a touch driving signal for maintaining the reference voltage after the high voltage pulse, and supplying the generated touch driving signal to the plurality of touch driving electrodes,
Wherein the reference voltage is maintained for a 1/2 period of the one frame period. 3. The method of claim 2,
The touch driving signal is generated so as to rise back to the original reference voltage after being lowered to the ground voltage for the first period before and after the high voltage pulse,
And applies the touch driving signal to the plurality of touch drives.

Images