KR102189570B1 - Display device with touch screen - Google Patents

Abstract

The present invention includes: a panel including m (m is a natural number of 3 or more) driving electrodes and n (n is a natural number of 3 or more) sensing electrodes arranged to intersect with the m driving electrodes; A touch driver for applying a first touch driving signal or a second touch driving signal to the m driving electrodes according to a driving mode of the panel; The present invention relates to a display device having a touch screen including a touch sensing unit that receives a touch sensing signal according to the first or second touch driving signal from the n sensing electrodes.

Description

Display device with touch screen {DISPLAY DEVICE WITH TOUCH SCREEN}

The present invention relates to a display device, and more particularly, to a display device having a touch screen.

In general, a sensing device capable of detecting the user's contact position is mounted on the display device or integrated with the display device, and various buttons or images are displayed on the screen of the display device, allowing the user's input directly on the screen. The display device is referred to as a display device having a touch screen. Since such a display device having a touch screen does not require an input device such as a keyboard, mouse, or keypad, it is widely used in various electronic devices including portable information terminals such as mobile phones and display devices other than computers. .

There are various methods such as a capacitive type, an electromagnetic type, and an optical type for the above-described touch screen to detect a user's touch input. Among them, the capacitive type touch screen includes a driving electrode and a sensing electrode. A touch input position is detected by detecting a change in capacitance between a driving electrode and a sensing electrode according to a touch input.

Hereinafter, a display device including a conventional capacitive touch screen will be described with reference to FIGS. 1 and 2.

1 is a diagram illustrating a display device having a conventional touch screen.

A display device having a conventional touch screen includes a panel 10, a touch driver 20, and a touch sensing unit 30, as shown in FIG. 1.

First, the panel 10 includes a plurality of driving electrodes 11 and a plurality of sensing electrodes 12 intersecting and arranged with the plurality of driving electrodes, and the plurality of driving electrodes 11 are connected to the touch driver 20. And a wiring 14 for connecting the plurality of sensing electrodes 12 to the touch sensing unit 30.

Further, the panel includes an antistatic ground wire 13 arranged in parallel with the plurality of sensing electrodes 12 in a non-display area outside the display area 15.

Next, the touch driver 20 sequentially applies a touch driving signal to the plurality of driving electrodes 11 so that a capacitance is formed between the plurality of driving electrodes 11 and the plurality of sensing electrodes 12.

Next, the touch sensing unit 30 includes a plurality of comparison units 31, and in the capacitance formed between the plurality of driving electrodes and the plurality of sensing electrodes, the amount of change in capacitance according to the user's touch input is calculated. By receiving through a plurality of sensing electrodes 12, the user's touch input position is sensed.

Here, the comparison unit 31 functions to detect a change in capacitance according to a user's touch input by performing an operation of comparing differences between touch sensing signals input through neighboring sensing electrodes.

A conventional touch screen integrated display device including the above-described various components operates by being divided into an active mode and an idle mode for the purpose of reducing power consumption. Here, the active mode refers to a user's touch input. When detected, it refers to a touch detection mode in which the exact touch coordinates according to the user's touch input are displayed on the display area of the panel, and the idle mode means touch detection to reduce the power consumption of the panel when there is no touch input on the panel for a certain period of time. It refers to a touch standby mode that does not perform a series of operations for.

In a conventional touch screen integrated display device that operates in an active mode and an idle mode, when the panel is in the idle mode, an operation to check whether a user's touch is input to the panel is performed with a constant pulse to transition from the idle mode to the active mode. Only then can it be switched to the active mode depending on the presence or absence of a touch input.

However, in a conventional display device having a touch screen, in the idle mode, the ground wiring 13 formed in the left non-display area of the panel shown in FIG. 1, the sensing electrode adjacent thereto, and the right non-display area of the panel are formed. Due to the capacitance generated from the ground wiring 13 and the sensing electrode adjacent thereto, an error of switching from the idle mode to the active mode may occur even though no touch is input to the panel.

Hereinafter, the above-described error will be described in more detail with reference to FIG. 2.

FIG. 2 is a diagram illustrating touch sensing waveforms in regions A and B shown in FIG. 1 according to a touch driving signal.

In the case of the idle mode as shown in FIG. 2, in the area A shown in FIG. 1, the capacitance CP1 formed between the ground wiring 13 formed in the non-display area and the first sensing electrode on the left side and the same ground wiring Due to the capacitance CP2 formed between the left second sensing electrode, the raw data value for touch sensing increases as shown in the graph of FIG. 2.

For example, the closer it is to the ground line, the larger the capacitance, so it is assumed that CP1 is 0.5 and CP2 is 0.2 in the A region, and the mutual capacitance formed between the first left sensing electrode and the second left sensing electrode is 1 Then, the total capacitance value at the left first sensing electrode in the area A becomes 1.5, and the total capacitance value at the left second sensing electrode becomes 1.2. Here, each capacitance value is input to the first comparator that compares the difference between the touch sensing signals for touch sensing, and in the first comparator, the total capacitance at the left first sensing electrode is relatively larger than the total capacitance value of the second left sensing electrode. Since the capacitance value is applied to the (+) side of the first comparator, the raw data value for touch detection increases.

Likewise, in the area B shown in FIG. 1, the capacitance CP1 formed between the ground wiring 13 formed in the non-display area and the first right sensing electrode, and the same ground wiring and the second right sensing electrode Due to the capacitance CP2, as shown in the graph of FIG. 2, the raw data value for touch sensing is lowered.

For example, the closer it is to the ground line, the larger the capacitance, so it is assumed that CP1 is 0.5 and CP2 is 0.2 in the B region, and the mutual capacitance formed between the first sensing electrode on the right and the second sensing electrode on the right is 1 Then, the total capacitance value at the right first sensing electrode in the region B becomes 1.5, and the total capacitance value at the right second sensing electrode becomes 1.2. Here, each capacitance value is input to the (n-1)-th comparator that compares the difference between the touch sensing signals for touch sensing, and the (n-1)-th comparator is relative to the total capacitance value of the second sensing electrode on the right. As the total capacitance value at the first large right sensing electrode is applied to the (-) side of the nth comparator, the raw data value for touch sensing falls.

As mentioned above, due to the capacitance between the ground wiring formed at both ends of the non-display area of the panel and the sensing electrodes adjacent to it, an error that goes to the active mode occurs even though no touch input occurs in the panel in the idle mode. In order to prevent such an error, a new sensing method is needed to check whether a touch is input in the idle mode.

The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide a display device having a touch screen capable of checking whether a touch is input without errors in an idle mode of a capacitive touch panel.

A display device having a touch screen according to an embodiment of the present invention for achieving the above object includes mm (m is a natural number of 3 or more) driving electrodes and n ( n is a natural number of 3 or more) of a panel including a sensing electrode; A touch driver configured to apply a first touch driving signal or a second touch driving signal to the m driving electrodes according to a driving mode of the panel; A touch sensing unit that receives a touch sensing signal according to the first or second touch driving signal from the n sensing electrodes, and is applied to the second to m-th (m is a natural number of 3 or more) driving electrodes among the m driving electrodes The second touch driving signal is composed of a compensation signal and a driving signal, the compensation signal applied to the second driving electrode is an inverted signal of the driving signal applied to the first driving electrode, and the compensation signal applied to the third driving electrode is second driving. It is an inversion signal of the driving signal applied to the electrode, and the compensation signal applied to the second driving electrode is applied to the second driving electrode at the same timing as the driving signal applied to the first driving electrode, and applied to the third driving electrode. The compensation signal is applied to the third driving electrode at the same timing as the driving signal applied to the second driving electrode.

According to embodiments of the present invention, in a display device having a touch screen, it is possible to check whether a panel is touched in an idle mode without error.

In addition, according to embodiments of the present invention, there is an effect of obtaining a uniform touch sensitivity regardless of capacitance between a ground line and a sensing electrode formed in a non-display area of a panel.

1 is a view showing a display device having a conventional touch screen;
2 is a diagram illustrating touch sensing waveforms in regions A and B shown in FIG. 1 according to a touch driving signal;
3A and 3B are views illustrating a panel of a display device having a touch screen according to an exemplary embodiment of the present invention;
4 and 5 are diagrams illustrating a display device having a touch screen and application of a touch driving signal according to an embodiment of the present invention; And
FIG. 6 is an enlarged view of area C shown in FIG. 5.

The display device of the present invention is a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), an organic light emitting diode display (Organic Light Emitting Display). , OLED), electrophoresis display device (Electrophoresis, EPD), etc. In the following embodiments, a liquid crystal display device is described as an example of a flat panel display device, but the display device of the present invention is not limited to a liquid crystal display device.

Hereinafter, some embodiments of the present invention will be described in detail with reference to the drawings. In adding reference numerals to elements of each drawing, the same elements may have the same numerals even if they are indicated on different drawings. In addition, in describing the present invention, when it is determined that a detailed description of a related known configuration or function may obscure the subject matter of the present invention, a detailed description thereof may be omitted.

In addition, in describing the constituent elements of the present invention, terms such as first, second, A, B, (a) and (b) may be used. These terms are only for distinguishing the component from other components, and the nature, order, order, or number of the component is not limited by the term.

The touch screen according to the present invention is a capacitive touch screen, which includes a driving electrode and a sensing electrode, and detects a touch input position by detecting a change in capacitance between the driving electrode and the sensing electrode according to the user's touch input. As a result, when a matrix is formed by crossing the driving electrode and the sensing electrode, and when a touch is made at an arbitrary position on the matrix, the coordinates of the driving electrode and the sensing electrode whose capacitance change when a driving signal is applied through the driving electrode are determined by the sensing electrode. It is a method of detecting the touch input location by receiving it through the device. The input means of the above-described capacitive touch screen may not only be a finger, but also any input means capable of causing a change in capacitance between the driving electrode and the sensing electrode.

In addition, in the capacitive touch screen according to the present invention, a driving electrode, a transparent substrate, and a sensing electrode are sequentially stacked, or a driving electrode, a transparent film, and a sensing electrode are sequentially stacked and bonded to a liquid crystal panel through an adhesive. It may be an add-on type touch screen, and an on-cell type touch in which a driving electrode and a sensing electrode are formed with an insulating layer interposed therebetween and are directly bonded to the liquid crystal panel through an adhesive. It may be a screen, or an in-cell type touch screen in which a driving electrode and a sensing electrode are formed inside a liquid crystal panel composed of an upper color filter and a lower TFT.

3A and 3B are diagrams illustrating a panel of a display device having a touch screen according to an exemplary embodiment of the present invention.

The panel 100 of a display device having a touch screen according to an embodiment of the present invention includes a display area 150 and a non-display area formed outside the display area within the panel, as shown in FIGS. 3A and 3B. It is divided into.

The display area 150 includes m (m is a natural number of 3 or more) driving electrodes 110 and n (n is a natural number of 3 or more) sensing electrodes intersecting and arranged with m driving electrodes, and a non-display area Includes the ground wiring 130. Here, the ground wiring is formed for the purpose of preventing static electricity of the panel, but the purpose of formation is not limited thereto.

The driving electrode and sensing electrode of FIG. 3A are formed by connecting single electrodes in a rhombus shape to form a driving electrode and a sensing electrode, and FIG. 3B is a bar-shaped driving electrode and a sensing electrode. It is one form.

3A and 3B are different only in the shape of the driving electrode and the sensing electrode, and are driven by the same driving method, and the driving electrode and the sensing electrode may be formed in other shapes other than the rhombus and bar shape shown in FIG. 3. That is, it does not matter what shape the electrode is formed as long as it is a driving electrode and a sensing electrode capable of driving a capacitive touch screen.

The above-described driving electrode 110 is an electrode to which a touch driving signal is sequentially applied through the wiring 140 and is represented by Tx1 to Tx(m), and the sensing electrode 120 is represented by Rx1 to Rx(n). , An electrode that forms a capacitance together with a driving electrode according to an applied touch driving signal, and transmits a change amount of capacitance generated according to a user's touch input to the outside through the wiring 140.

Hereinafter, a display device having a touch screen and driving thereof according to an exemplary embodiment will be described in detail with reference to the description of the panel of FIG. 3 described above.

4 and 5 are diagrams illustrating a display device having a touch screen and application of a touch driving signal according to an exemplary embodiment of the present invention.

In particular, the display device according to an embodiment of the present invention operates in an active mode and an idle mode for the purpose of reducing power consumption. The active mode refers to a touch driving mode shown in FIG. 4. When a user's touch input is detected, it refers to a touch sensing mode in which accurate touch coordinates according to the user's touch input are displayed on the display area of the panel, and the idle mode is a touch driving mode shown in FIG. When there is no input, it refers to a touch standby mode in which a series of operations for touch sensing is not performed for the purpose of reducing power consumption of the panel.

For reference, in the present invention, the driving mode of the panel to which the first touch driving signal is applied is defined as an active mode that senses the coordinates of the touch input, and the mode of the panel to which the second touch driving signal is applied is the touch It will be defined as an idle mode that determines the presence or absence of an input. A description of the first and second touch driving signals will be described in detail below.

4 and 5, the touch screen integrated display device according to an embodiment of the present invention further includes a touch driver 200 and a touch sensing unit 300 in addition to the panel 100 mentioned above, With reference to FIGS. 4 and 5, application of a touch driving signal according to an active mode and an idle mode will be described.

The embodiment shown in FIG. 4 is an embodiment of application of a touch driving signal from the touch driver 200 when the panel is operated in an active mode.

When the panel 100 is operated in an active mode, the touch driver 200 sequentially applies a first touch driving signal to the m driving electrodes 110, and the touch sensing unit 300 applies the first touch driving signal. A touch sensing signal according to a touch driving signal is received from the n sensing electrodes 120.

In other words, the touch driver 200 sequentially applies the first touch driving signal from the first driving electrode to the m-th driving electrode, and according to the sequentially applied first touch driving signal, m driving electrodes 110 and n number of driving electrodes are applied. A capacitance is formed between the sensing electrodes 120. Here, the first touch driving signal is a signal comprising only a driving signal applied for touch sensing.

In the touch sensing unit 300, in the capacitance formed between m driving electrodes and n sensing electrodes, the amount of change in capacitance (touch sensing signal) according to the user's touch input is received through n sensing electrodes 120 Thus, the user's touch input coordinates are detected.

Here, the touch sensing unit includes (n-1) comparison units 310, and the comparison unit performs an operation of comparing the difference between the touch sensing signals input through neighboring sensing electrodes. It functions to detect the amount of change in capacitance.

To describe the sensing operation of the touch sensing unit 300 in more detail, the comparison unit 310 is connected between neighboring sensing electrodes, and the comparison unit amplifies the difference between touch sensing signals input through the neighboring sensing electrodes. To output the amplified difference voltage.

For example, the first comparison unit outputs a difference voltage between signals input through the first sensing electrode Rx1 and the second sensing electrode Rx2, and the second comparison unit outputs the second sensing electrode Rx2 and the third sensing electrode. The difference voltage between the signals input through (Rx3) is output. In addition, the comparison units 310 amplify a voltage difference between signals input through neighboring sensing electrodes. As such, the comparators play a role of improving the signal-to-noise ratio (SNR) by reducing the noise component introduced by the parasitic capacitance of the touch screen (TSP) by outputting and amplifying the difference voltage between signals input through neighboring sensing electrodes. do.

The touch sensing unit 300 responds to a user's touch input in the capacitance formed between the m driving electrodes and the n sensing electrodes through the n sensing electrodes and the amplified difference voltage received through the comparison unit 310. The amount of change in capacitance is sensed and converted into digital data. To this end, the touch sensing unit 300 includes an analog to digital converter (hereinafter referred to as “ADC”). The digital data converted by the ADC is supplied to the system unit (not shown) as raw data for touch sensing, and displays the touch coordinates on the display area of the panel.

For reference, even in the active mode, as mentioned in the conventional idle mode, touch due to the capacitance between the ground wiring 130 formed at both ends of the non-display area of the panel and adjacent sensing electrodes (Rx1 or Rx(n)) Sensing errors may occur, but such errors can be solved using a reference buffer. That is, assuming that the reference data value is 2048, the data value of the rising part (Rx1) is 3000, and the data value of the falling part is 1000, the reference data is to compensate for the rising or falling part compared to the reference data value. The error can be resolved by reflecting the value to the current data value and adjusting the raw data value of the rising or falling part to the data value as a reference.

The embodiment shown in FIG. 5 is an embodiment of application of a touch driving signal from the touch driver 200 when the panel operates in an idle mode.

When the panel 100 is operated in an idle mode, the touch driver 200 sequentially applies a second touch driving signal to the m driving electrodes 110, and the touch sensing unit 300 applies a second touch driving signal. A touch sensing signal according to a touch driving signal is received from the n sensing electrodes 120.

Here, the second touch driving signal applied to the first driving electrode among the m driving electrodes consists of only the driving signal applied for touch sensing, and is used as the second to m-th (m is a natural number of 3 or more) driving electrodes among the m driving electrodes. The applied second touch driving signal includes a compensation signal and a driving signal. Here, the compensation signal refers to a signal applied before the driving signal based on the same driving electrode.

The above-described compensation signal applied to the second driving electrode is an inverted signal of the driving signal applied to the first driving electrode, the compensation signal applied to the third driving electrode is an inverted signal of the driving signal applied to the second driving electrode, and the m-th driving The compensation signal applied to the electrode is an inverted signal of the driving signal applied to the (m-1)-th driving electrode.

And, the compensation signal applied to the second drive electrode is applied to the second drive electrode at the same timing as the drive signal applied to the first drive electrode, and the compensation signal applied to the third drive electrode is the same timing as the drive signal applied to the second drive electrode. The compensation signal applied to the third driving electrode and applied to the m-th driving electrode is applied to the m-th driving electrode at the same timing as the driving signal applied to the (m-1)-th driving electrode.

In other words, the compensation signal applied to the second electrode is applied at the same timing as the driving signal applied to the first driving electrode, and the compensation signal applied to the third to m-th driving electrodes is applied to the previous driving electrode at the same timing as the driving signal. It is applied and serves to cancel a driving signal (a driving signal applied for touch detection) applied to the first to (m-1)-th driving electrodes.

When the panel is operated in the idle mode, it is a mode for switching the panel to the active mode by detecting only the presence or absence of a user's touch input, so there is no need to detect accurate touch coordinates, so the first to the (m-1)th drive as in the above-described embodiment Even if the driving signal applied to the electrode for touch sensing is canceled through the compensation signal from the next driving electrode, no problem occurs in driving for the presence or absence of a touch input.

Moreover, by canceling the driving signal applied to sense the touch of the previous driving electrode, in the case of the idle mode, some touch on the panel due to the capacitance between the ground wires formed at both ends of the non-display area of the panel and adjacent sensing electrodes. There is an effect of preventing an error from switching to the active mode even though no input has occurred.

Finally, a method of offset driving of a driving signal applied to sense a touch applied to the first to (m-1)-th driving electrodes mentioned in FIG. 5 will be described with reference to FIG. 6.

6 is an enlarged view of area C shown in FIG. 5.

As shown in FIG. 6, when driving in the idle mode, the capacitance Cm of the driving signal Pulse in the first driving electrode Tx1 is charged with a Cp value due to the application of the positive phase signal, and the second driving electrode Tx2 ), the Cp value is discharged due to the application of a phase-inverted reverse phase signal to the positive phase signal of the driving signal in the first driving electrode.

In addition, the capacitance Cm of the driving signal Pulse in the second driving electrode Tx2 is charged with the Cp value due to the application of the positive phase signal Pulse, and the compensation signal (Pulse Bar) in the third driving electrode Tx3 The Cp value is discharged due to the application of a phase-inverted reverse phase signal (Pulse Bar) to the positive phase signal of the driving signal in the second driving electrode. Here, the Cp value is an increase or decrease in capacitance due to a signal.

As such, the Cp values of the driving signal (Pulse) applied to the first and second driving electrodes and the compensation signal (Pulse Bar) applied to the second and third driving electrodes are mutually inverted values due to the forward and reverse phase signals, so they are mutually cancelled. As a result, since the Cp value becomes almost 0, there is no effect due to the capacitance between the ground wiring formed at the ends of the non-display area of the panel and adjacent sensing electrodes.

Of course, the driving method that cancels the driving signal (Pulse) cannot display the exact touch coordinates on the display area of the panel like driving in the active mode, but it is only possible to check the presence or absence of a touch input on the panel in the idle mode. Let's do it.

Those skilled in the art to which the present invention pertains will appreciate that the above-described present invention can be implemented in other specific forms without changing the technical spirit or essential features thereof.

Therefore, it should be understood that the embodiments described above are illustrative in all respects and not limiting. The scope of the present invention is indicated by the claims to be described later rather than the detailed description, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. do.

100: panel 110: driving electrode
120: sensing electrode 130: ground wiring
140: wiring 150: display area
200: touch driver 300: touch sensing unit
310: comparator

Claims (13)

a panel including m (m is a natural number of 3 or more) driving electrodes and n (n is a natural number of 3 or more) sensing electrodes arranged intersecting with the m driving electrodes;
A touch driver for applying a first touch driving signal to the m driving electrodes in a first driving mode of the panel, and for applying a second touch driving signal by switching to a second driving mode when no touch input is detected for a predetermined period of time; And
A touch sensing unit receiving a touch sensing signal according to the first or second touch driving signal from the n sensing electrodes,
The second touch driving signal applied to the i (i is a natural number from 2 to m)-th driving electrode includes a driving signal and a compensation signal,
The compensation signal applied to the i-th driving electrode is an inverted signal of the driving signal applied to the i-1th driving electrode,
When the occurrence of a touch is sensed based on the second touch driving signal during the second driving mode, the touch driver switches to the first driving mode. The method of claim 1,
A display device with a touch screen, wherein the compensation signal applied to the i-th driving electrode is applied to the i-1th driving electrode at the same timing as the driving signal applied to the i-1th driving electrode. The method of claim 1,
A display device with a touch screen, wherein the compensation signal applied to the m-th driving electrode is an inverted signal of the driving signal applied to the (m-1)-th driving electrode. The method of claim 3,
A display device with a touch screen, wherein the compensation signal applied to the m-th driving electrode is applied to the m-th driving electrode at the same timing as the driving signal applied to the (m-1)-th driving electrode. The method of claim 1,
The second touch driving signal is applied to the i- th driving electrode in the order of the compensation signal and the driving signal. The method of claim 1,
The display device with a touch screen, characterized in that the second touch driving signal applied to the first driving electrode among the m driving electrodes comprises only a driving signal. The method of claim 1,
The first touch driving signal includes a driving signal applied to a j (j is a natural number from 1 to m)-th driving electrode, and is sequentially applied from the first driving electrode to the m-th driving electrode. Equipped display device. The method of claim 1,
The first driving mode is an active mode for sensing coordinates of a touch input,
The second driving mode is an idle mode for determining the presence or absence of a touch input. The method of claim 1,
The touch sensing signal is a change amount of the capacitance according to a touch input in capacitance formed between the m driving electrodes and n sensing electrodes. The method of claim 1, wherein the panel,
The display device with a touch screen, further comprising at least one ground wire disposed adjacent to the m driving electrodes. The method of claim 10, wherein the touch sensing signal,
And a capacitance value between the m driving electrodes and the at least one ground wire. The method of claim 10, wherein in the second driving mode,
The capacitance value between the i-1 th driving electrode to which a driving signal is applied and the at least one ground wire is canceled by the capacitance between the i-th driving electrode to which the compensation signal is applied and the at least one ground wire. A display device having a touch screen, characterized in that. The method of claim 1,
The sensing electrode includes a first sensing electrode, a second sensing electrode, a third sensing electrode, and a fourth sensing electrode,
The touch sensing unit includes at least one first comparison unit and a second comparison unit,
The first comparison unit outputs a difference voltage between the turn sensing signals input through the first sensing electrode and the second sensing electrode,
And the second comparing unit outputs a voltage difference between the touch sensing signals input through the third sensing electrode and the fourth sensing electrode.

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