KR102285909B1 - Touch sensor intergrated type display device - Google Patents

Abstract

The touch sensor integrated display device of the present invention includes a display panel including a common electrode, a touch screen panel, an inversion compensator, a voltage follower, and a first switching unit. The touch screen panel faces the display panel and receives a Tx driving signal through a Tx line. The inversion compensator receives the feedback common voltage returned from the common electrode and outputs a compensating common voltage. The voltage follower receives the constant potential common voltage and outputs an amplified constant potential common voltage. The first switching unit has a first input terminal connected to an output terminal of the inversion compensator, a second input terminal connected to an output terminal of the voltage follower, and provides an output terminal with a signal received through the second input terminal during the touch sensing period.

Description

Touch sensor integrated display device {TOUCH SENSOR INTERGRATED TYPE DISPLAY DEVICE}

The present invention relates to a touch sensor integrated display device.

A user interface (UI) enables communication between a person (user) and various electrical and electronic devices, so that the user can easily control the device as he or she wants. Representative examples of the user interface include a keypad, a keyboard, a mouse, an on-screen display (OSD), and a remote controller having an infrared communication function or a radio frequency (RF) communication function. User interface technology is developing in the direction of increasing user sensitivity and ease of operation.

Recently, in order to slim down portable terminals such as smart phones and tablet PCs, the demand for an in-cell type touch screen-integrated display device in which elements constituting a touch screen is built in a display device is increasing.

The panel-embedded touch screen integrated display device divides the common electrodes for display into a plurality of touch driving regions and a plurality of touch sensing regions so that mutual capacitance is generated between the touch driving region and the touch sensing region. A touch is recognized by measuring the amount of change in mutual capacitance.

In the conventional panel-embedded touch screen integrated display device, in order to simultaneously perform a display function and a touch function, the common electrodes for the display simultaneously perform the function of the touch electrode when the panel operates in the touch sensing mode. In addition, the common electrode receives the same common voltage in the image display section and in the touch sensing mode, and in this process, the common voltage level of the base voltage in the touch sensing mode may cause an unstable state. If the common voltage level is unstable in the touch sensing mode, there is a problem in that the sensing operation is not smoothly performed.

An object of the present invention is to provide a touch sensor-integrated display device capable of improving a common voltage level from being unstable in a touch sensing mode.

The touch sensor integrated display device of the present invention includes a display panel including a common electrode, a touch screen panel, an inversion compensator, a voltage follower, and a first switching unit. The touch screen panel faces the display panel and receives a Tx driving signal through a Tx line. The inversion compensator receives the feedback common voltage returned from the common electrode and outputs a compensating common voltage. The voltage follower receives the constant potential common voltage and outputs an amplified constant potential common voltage. The first switching unit has a first input terminal connected to an output terminal of the inversion compensator, a second input terminal connected to an output terminal of the voltage follower, and provides a signal received through the second input terminal as an output terminal during the touch sensing period.

According to the present invention, since the driving signal is output using the constant potential common voltage during the touch sensing period, it is possible to improve the voltage level from being unstable due to the inversion compensation signal.

1 is a view showing a touch sensor-integrated display device according to an embodiment of the present invention.
2 is an equivalent circuit diagram of a liquid crystal cell.
3 is an equivalent circuit diagram of a touch screen;
Fig. 4 is a diagram showing an example of a structure of a touch screen array;
5 is a view showing a Tx driving signal generator according to an embodiment of the present invention.
6 is a waveform diagram of a Tx driving signal according to the present invention.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals refer to substantially identical elements throughout. In the following description, if it is determined that a detailed description of a known function or configuration related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

1 is a view showing a touch sensor integrated display device according to an embodiment of the present invention. FIG. 2 is an equivalent circuit diagram of a pixel of the display panel shown in FIG. 1 , and FIG. 3 is an equivalent circuit diagram of a touch screen. And Fig. 4 is a view showing the array structure of the touch screen panel.

A display device according to an embodiment of the present invention includes a display panel (DIS), a display driving circuit, a touch screen (TSP), a touch screen driving circuit, and the like.

The display panel DIS includes a liquid crystal layer formed between two substrates. On the lower substrate of the display panel DIS, a plurality of data lines (D1 to Dm, m is a natural number), a plurality of gate lines (G1 to Gn, n is a natural number) crossing the data lines (D1 to Dm), A plurality of TFTs (Thin Film Transistors) formed at intersections of the data lines D1 to Dm and the gate lines G1 to Gn, and a plurality of pixel electrodes 1 for charging the data voltage to the liquid crystal cells , and a storage capacitor (Cst) connected to the pixel electrode 1 to maintain the voltage of the liquid crystal cell.

The pixel array of the display panel DIS includes pixels formed in a pixel area defined by data lines D1 to Dm and gate lines G1 to Gn. Each of the pixels may include a liquid crystal cell as shown in FIG. 2 . Each liquid crystal cell of the pixels is driven by an electric field applied according to the voltage difference between the data voltage applied to the pixel electrode 1 and the common voltage Vcom applied to the common electrode 2 to control the amount of transmitted light. do. The TFTs are turned on according to a gate pulse from the gate lines G1 to Gn to supply the data voltage from the data lines D1 to Dm to the pixel electrode 1 of the liquid crystal cell.

The upper substrate of the display panel DIS may include a black matrix, a color filter, and the like. The lower substrate of the display panel DIS may be implemented in a color filter on TFT (COT) structure. In this case, the black matrix and the color filter may be formed on the lower substrate of the display panel DIS. The common electrode 2 may be formed on an upper substrate or a lower substrate of the display panel DIS.

A polarizing plate is attached to each of the upper and lower substrates of the display panel DIS, and an alignment layer for setting a pretilt angle of the liquid crystal is formed on the inner surface in contact with the liquid crystal. A column spacer for maintaining a cell gap of the liquid crystal cell is formed between the upper substrate and the lower substrate of the display panel DIS.

A backlight unit may be disposed under the rear surface of the display panel DIS. The backlight unit is implemented as an edge type or direct type backlight unit to irradiate light to the display panel DIS. The display panel DIS may be implemented in any known liquid crystal mode, such as a twisted nematic (TN) mode, a vertical alignment (VA) mode, an in plane switching (IPS) mode, and a FRMnge field switching (FFS) mode.

The display driving circuit includes the data driving circuit 12 , the scan driving circuit 14 , and the display timing controller 20 to write the video data voltage of the input image to the pixels of the display panel DIS. The data driving circuit 12 converts digital video data RGB input from the display timing controller 20 into analog positive/negative gamma compensation voltages and outputs a data voltage. The data voltage output from the data driving circuit 12 is supplied to the data lines D1 to Dm. The scan driving circuit 14 sequentially supplies a gate pulse (or scan pulse) synchronized with the data voltage to the gate lines G1 to Gn to select a line of the display panel DIS to which the data voltage is written. The pixels of the display panel DIS are charged with the data voltage input from the data driving circuit 12 within the high logic section of the horizontal synchronization signal Hsync in response to the scan pulse, and the horizontal synchronization signal Hsync ) maintains the data voltage during the low logic period.

The display timing controller 20 receives timing signals such as a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a data enable signal DE, and a main clock MCLK input from the host system 40 . The input is received to synchronize the operation timings of the data driving circuit 12 and the scan driving circuit 14 . The vertical synchronization signal Vsync is a signal defining one frame period. One period of the vertical synchronization signal Vsync is set to one frame period as shown in FIG. 7 . The horizontal synchronization signal Hsync defines one horizontal period required to write data to pixels of one line in the pixel array of the display panel DIS. One horizontal period may be calculated by dividing one frame period by the number of lines of the display panel DIS. One period of the horizontal synchronization signal Hsyc is set to one horizontal period. When the data enable signal DE defines a period in which valid data is input, one period is set to one horizontal period as the horizontal synchronization signal Hsync. The pulse of the data enable signal DE is not generated during the vertical blank period VB, but is generated in synchronization with data corresponding to one line only when valid data is input. The vertical blank period VB is a period in which no data is input between the I (I is a positive integer)-th frame period and the I+1-th frame period. The main clock signal MCLK is synchronized with each bit of digital video data.

The display timing controller 20 generates a scan timing control signal and a data timing control signal for controlling operation timings of the data driving circuit 12 and the scan driving circuit 14 . The scan timing control signal includes a gate start pulse (GSP), a gate shift clock (Gate Shift Clock), a gate output enable signal (Gate Output Enable, GOE), and the like. The data timing control signal includes a source sampling clock (Source Sampling Clock, SSC), a polarity control signal (PolaRMty, POL), and a source output enable signal (Source Output Enable, SOE).

The touch screen TSP includes Tx lines (T1 to TN, where N is a positive integer less than n) and Rx lines (R1 to RM, M is a positive integer less than m) intersecting the Tx lines (T1 to TN). integer), and M×N touch sensors Cts formed at intersections of Tx lines T1 to TN and Rx lines R1 to RM. Each of the touch sensors Cts includes a mutual capacitance.

4 is an enlarged plan view of Tx electrodes and some of Rx electrodes in an in-cell type touch screen (TSP). Referring to FIG. 4 , the in-cell type touch screen (TSP) will be described in more detail as follows.

Each of the Tx lines includes transparent Tx channel electrodes T11 to T13 and T21 to T23 connected along the lateral direction (the x-axis direction of FIG. 1 ) of the display panel DIS through link patterns L11 to L22. do. The first Tx line T1 includes the transparent Tx channel electrodes T11 to T13 connected in the lateral direction via the link patterns L11 and L12. The second Tx line T2 includes the transparent Tx channel electrodes T21 to T23 connected in the lateral direction via the link patterns L21 and L22. The size of each of the transparent Tx channel electrodes T11 to T23 is larger than the size of the pixels and overlaps with a plurality of pixels. Each of the transparent Tx channel electrodes T11 to T23 overlaps the pixel electrodes 1 with an insulating layer interposed therebetween. Each of the transparent Tx channel electrodes T11 to T23 may be formed of a transparent conductive material such as indium tin oxide (ITO). The link patterns L11 to L22 cross the Rx lines R1 and R2 and electrically connect the adjacent transparent Tx channel electrodes T11 to T23 in a lateral direction (or a horizontal direction). The link patterns L11 to L22 may overlap the Rx lines R1 and R2 with an insulating layer interposed therebetween. Link patterns L11 to L22 are formed of a metal having high electrical conductivity, for example, a metal such as aluminum (Al)-based metal, molybdenum (Mo), chromium (Cr), copper (Cu), silver (Ag), or the like; It may be formed of a transparent conductive material.

The Rx lines R1 and R2 are formed along the longitudinal direction (y-axis direction in FIG. 1 ) of the display panel DIS to be orthogonal to the Tx lines. The Rx lines R1 and R2 may be formed of a transparent conductive material such as ITO. Each of the Rx lines R1 and R2 may overlap a plurality of pixels (not shown).

The touch screen driving circuit 30 applies the Tx driving signal to the Tx lines T1 to TN for each low logic section of the horizontal synchronization signal Hsync, and the touch sensors Cts through the Rx lines R1 to RM. sense the voltage of The low logic period of the horizontal synchronization signal Hsync includes a vertical blank period VB and a horizontal blank period HB as shown in FIG. 7 . The vertical blank period VB is a period in which data is not input between adjacent frame periods as described above. The horizontal blank period HB is a period in which data is not written into pixels between adjacent lines in the pixel array of the display panel DIS. The horizontal blank period HB is equal to the time between consecutively generated gate pulses.

The touch screen driving circuit 30 includes a Tx driving circuit 32 , an Rx driving circuit 34 , and a touch screen controller 36 (hereinafter referred to as “TSP controller”).

The Tx driving circuit 32 selects a Tx channel to output a Tx driving signal in response to a Tx setup signal input from the TSP controller 36 , and transmits a Tx driving signal to Tx lines T1 to TN connected to the selected Tx channel. to authorize The Tx lines T1 to TN are charged during the high potential section of the Tx driving signal to supply electric charges to the touch sensors Cts, and are discharged during the low potential section of the Tx driving signal. The Tx driving signal is N to each of the Tx lines T1 to TN so that the voltages of the touch sensors Cts can be accumulated in the integrator in the Rx driving circuit 34 through the Rx lines R1 to RM. (N is a positive integer of 2 or more) may be continuously supplied.

The Rx driving circuit 34 selects the Rx lines R1 to RM to receive the voltage of the touch sensor in response to the Rx setup signal input from the TSP controller 36 . The Rx driving circuit 34 samples the voltages of the touch sensors Cts received through the Rx lines R1 to RM and accumulates them in the integrator. And the Rx driving circuit 34 converts the voltage accumulated in the integrator into digital data using an analog-to-digital converter (hereinafter referred to as "ADC") connected to the output terminal of the integrator to convert the touch raw data (Touch raw data). data) is output.

The TSP controller 36 receives the Tx setup signal for setting the Tx channel to which the Tx driving signal is output from the Tx driving circuit 32 and the Rx channel for receiving the voltages of the touch sensors Cts from the Rx driving circuit 34 . The sensing operation of the Tx driving circuit 32 and the Rx driving circuit 34 is synchronized by generating an Rx setup signal for setting . In addition, the TSP controller 36 generates timing control signals for controlling the operation timing of the sampling and integrator of the Rx driving circuit 34 and the operation timing of the ADC.

The TSP controller 36 receives the horizontal synchronization signal Hsync from the host system 40 and based on the horizontal synchronization signal Hsync, the Tx driving circuit 32 and the Rx driving circuit during the time-divided touch sensing period Ts. (34) is driven. The Tx driving circuit 32 and the Rx driving circuit 34 sense the voltages of the touch sensors during the allocated touch sensing period Ts within the low logic period of the horizontal synchronization signal Hsync under the control of the TSP controller 36 . .

The TSP controller 36 compares the touch raw data received from the Rx driving circuit 34 with a preset threshold by executing a preset touch recognition algorithm. The touch recognition algorithm determines touch raw data equal to or greater than the threshold as data input from touch sensors of touch (or proximity) input positions, and calculates coordinates of each of touch (or proximity) input positions. In addition, the TST controller 36 transmits the touch report data TR to the host system 40 at a touch report rate higher than the display frame rate. The touch report data is generated after it is determined by the touch recognition processor 70 whether a touch is input to all touch sensors in the touch screen, and includes coordinate information of each of touch (or proximity) input positions.

The host system 40 may be implemented as any one of a navigation system, a set-top box, a DVD player, a Blu-ray player, a personal computer (PC), a home theater system, a broadcast receiver, and a phone system. The host system 40 includes a system on chip (SoC) having a built-in scaler and converts digital video data RGB of an input image into a format suitable for display on the display panel DIS. The host system 40 transmits the timing signals Vsync, Hsync, DE, and MCLK together with the digital video data to the display timing controller 20 . In addition, the host system 40 executes an application program associated with the coordinate values of the touch report data TR input from the TSP controller 36 .

5 is a view showing a Tx driving signal generator 300 and a driving signal supply line of the Tx driving circuit 30 according to an embodiment of the present invention. And FIG. 6 is a waveform diagram showing an output of the Tx driving signal generator 300 .

Referring to FIG. 5 , the Tx driving signal generator 300 according to an embodiment of the present invention supplies a Tx driving signal through a driving signal supply line OL, and a feedback common voltage Vcom_feedback through a feedback line FL. ) is input. In addition, the Tx driving signal generator 300 includes an inversion compensator 310 , a voltage follower 321 , a first switch unit 330 , and a second switch unit 340 .

The inversion compensator 310 includes an operational amplifier 311 , a capacitor C, a first input resistor R1 and a second input resistor R2 . The first operational amplifier 311 receives the constant potential common voltage Vcom_DC through the first input channel and the feedback common voltage Vcom_feedback through the second input channel. The output terminal of the first operational amplifier 311 is connected to the first switch unit 330 . The capacitor C maintains the voltage level of the feedback common voltage Vcom_feedback. The inversion compensator 310 receives the feedback common voltage Vcom_feedback and outputs the compensation common voltage Vcom_com.

The voltage follower 320 includes a buffer 321 , a third input resistor R3 , and a fourth input resistor R4 . The buffer 321 receives the constant potential common voltage Vcom_DC through the first input channel, and the second input channel is connected to the ground voltage source GND. The constant potential common voltage Vcom_DC may be provided from a common voltage generation circuit such as a power module (not shown). The voltage follower 320 outputs a common voltage of a DC component provided from the constant potential common voltage Vcom_DC.

The first switch unit 330 receives an output of the inversion compensator 310 through a first input terminal, and receives an output of the voltage follower 320 through a second input terminal. In addition, the first switch unit 330 outputs the output of the inversion compensator 310 or the output of the voltage follower 320 to the driving signal supply line OL according to the touch synchronization signal Tsync. The touch synchronization signal Tsync maintains a high level during the display period Tdisplay and maintains a low level during the touch sensing period Ttouch. The first switch unit 330 connects the output terminal of the inversion compensator 310 to the second switch unit 340 in response to the high level signal, and connects the output terminal of the voltage follower 320 to the second switch unit 340 in response to the low level signal. A MUX connected to the switch unit 340 may be used.

The second switch unit 340 receives the output voltage of the first switch unit 330 through the third input terminal, and receives the Tx high voltage HVCC through the fourth input terminal, so that the The output voltage or Tx high voltage (HVCC) is selectively output.

The second switch unit 340 connects the output voltage of the first switch unit 330 and the driving signal supply line OL during the display period Tdisplay. That is, during the display period Tdisplay, the compensation common voltage Vcom_com is output as a Tx driving signal. Since the compensation common voltage Vcom_com is a voltage compensated using the feedback common voltage Vcom_feedback, it is possible to compensate for the common voltage being unstable due to coupling of the data voltage.

The second switch unit 340 performs a switching operation to selectively output the output voltage or Tx high voltage HVCC of the first switch unit 330 during the touch sensing period Ttouch. That is, during the touch sensing period Ttouch, the Tx driving signal swings between the constant potential common voltage Vcom_DC and the Tx high voltage HVCC.

As described above, the Tx driving signal generator 300 uses the constant potential common voltage Vcom_DC as the base voltage of the Tx driving signal output during the touch sensing period Ttouch. Accordingly, when the Tx driving signal swings between the constant potential common voltage Vcom_DC and the Tx high voltage HVCC, the voltage level of the constant potential common voltage Vcom_DC, which is the base voltage, is stabilized.

In comparison with the embodiment of the present invention, when the base voltage of the Tx driving signal is used as the compensation common voltage Vcom_com in the touch sensing period Ttouch, the voltage level becomes unstable. For this reason, since the inversion compensator 310 inverts and outputs the feedback common voltage Vcom_feedback, the voltage level of the output of the inversion compensator 310 is not stabilized in the period in which the Tx high voltage HVCC is output. As such, when the voltage level of the Tx driving signal is unstable, the touch sensitivity is adversely affected.

In contrast, in the embodiment of the present invention, since the constant potential common voltage Vcom_DC is used as the base voltage during the touch sensing period Ttouch, the voltage level of the Tx driving signal is stabilized. Accordingly, the touch sensitivity can be improved.

Those skilled in the art from the above description will be able to see that various changes and modifications can be made without departing from the technical spirit of the present invention. Accordingly, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

DIS : Display panel TSP : Touch screen
12: data driving circuit 14: scan driving circuit
20: display timing controller 30: touch screen driving circuit
32: Tx driving circuit 34: Rx driving circuit
36: TSP controller 300: Tx driving signal generator
310: inversion compensator 320: voltage follower
330: first switching unit 340: second switching unit

Claims (5)

a display panel including a common electrode;
a touch screen panel facing the display panel and receiving a Tx driving signal swinging between a base voltage and a high voltage through a Tx line;
an inversion compensator receiving the feedback common voltage returned from the common electrode and outputting a compensation common voltage;
a voltage follower receiving the constant potential common voltage provided from the common voltage generating circuit and outputting the amplified constant potential common voltage; and
A first input terminal is connected to an output terminal of the inversion compensator, a second input terminal is connected to an output terminal of the voltage follower, and during a touch sensing period, a signal received through the second input terminal is provided as an output terminal, and during a display period , comprising a first switching unit for providing the compensation common voltage received through the first input terminal to an output terminal,
The constant potential common voltage is
A touch sensor integrated display device provided to the touch screen panel as the base voltage of the Tx driving signal.
delete The method of claim 1,
The first switching unit
receiving a touch synchronization signal that maintains a high level during the display period and maintains a low level during the touch sensing period;
connecting the first input terminal and the output terminal in response to the high-level touch synchronization signal;
A touch sensor-integrated display device implemented as a mux connecting the second input terminal and the output terminal in response to the low-level touch synchronization signal.
The method of claim 1,
A third input terminal is connected to the output terminal of the first switching unit,
Tx high voltage is input through the fourth input terminal,
Further comprising a second switching unit for selectively outputting an output of the output terminal of the first switching unit or the Tx high voltage during the touch sensing period,
The Tx high voltage is
A touch sensor integrated display device provided to the touch screen panel as the high voltage of the Tx driving signal.
The method of claim 1,
The inversion compensator
and an operational amplifier receiving the feedback common voltage through a first input channel and receiving the constant potential common voltage through a second input channel.

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