KR20120118731A - Display having touch sensor and method for amplifying output sygnal from the touch sensor - Google Patents

Abstract

PURPOSE: A display device with a touch sensor and an output signal amplification method of the touch sensor are provided to remove high frequency noise components by adding dummy data to be calculated over a cofactor. CONSTITUTION: Dummy data is added to the left side or the right side of digital data to be amplified(S1,S2). Window data is extracted from digital touch data(S3). The extracted window data is matched to cofactors and the digital data and the cofactors are multiplied. The digital touch data located in the center of the window data is amplified(S4,S5). [Reference numerals] (AA) Window size; (BB) Cofactor; (S0) Cofactor matrix; (S1) Digital touch data of a corner/edge unit?; (S2) Dummy data addition; (S3) Window data extraction; (S4) ∑(Cofactor digital touch data); (S5) Data amplification; (S6) All data amplification?

Description

DISPLAY HAVING TOUCH SENSOR AND METHOD FOR AMPLIFYING OUTPUT SYGNAL FROM THE TOUCH SENSOR}

The present invention relates to a display device having a touch sensor and a method of amplifying an output signal of the touch sensor.

The user interface (UI) enables communication between a person (user) and various electric and electronic devices, so that the user can easily control the device as desired. Representative examples of the user interface include a keypad, a keyboard, a mouse, an on-screen display (OSD), a remote controller having infrared communication or radio frequency (RF) communication. User interface technology has been developed to enhance the user's sensibility and ease of operation. Recently, the genetic interface has evolved into a touch UI, a speech recognition UI, a 3D UI, and the like.

In accordance with the trend toward lighter and slimmer home appliances and portable information devices, user input means are being replaced by touch screens from button switches. The touch screen includes a plurality of touch sensors and is mounted on the display panel of the display element. Recently, a form in which a touch screen is embedded in a display panel has also been developed.

Since the difference between the touch sensor output signal of the touch position and the output signal of the non-touch touch sensor is large, it is easy to determine whether there is a touch, and thus the sensitivity of the touch screen may be increased. The touch sensor output signal is very small. The difference between the touch sensor output signal that is touched and the touch sensor output signal that is not touched is small. In addition, the touch sensor output signal includes high frequency noise due to coupling with driving signals of the pixel array or electromagnetic interference (EMI). Therefore, in order to increase the sensitivity of the touch screen and prevent the malfunction of the touch screen, there is a need for a method of amplifying the touch sensor output signal and removing noise components included in the touch sensor output signal.

The present invention provides a display device having a touch sensor capable of amplifying an output signal of a touched sensor and removing a noise component included in the touch sensor output signal, and a method of amplifying an output signal of the touch sensor.

The display device of the present invention includes a touch screen including a plurality of touch sensors; A touch sensor reading circuit converting an output of each of the touch sensors into digital touch data; And a cofactor matrix including 1 × N (N is an odd number of 3 or more) cofactors arranged in a line type and a cofactor matrix including N × N cofactors arranged in a matrix type, respectively. And a touch sensor output amplifying circuit for amplifying the digital touch data obtained from the same.

The touch sensor output amplifying circuit extracts the digital touch data by the size of the cofactor matrix, matches the cofactors and the digital touch data by 1: 1, multiplies them, and adds the results to add the digital touch data. Amplify.

The touch sensor output amplifying circuit selects preset dummy data as data outside the touch screen when amplifying digital touch data located at corners and edges of the touch screen, and is arranged in an area outside the touch screen. Is multiplied by the dummy data, and the multiplication result is summed with other multiplication results.

The method for amplifying an output signal of the touch sensor may include converting an output of each touch sensor into digital touch data; Setting one of a cofactor matrix having 1 × N (N is an odd number of 3) cofactors arranged in a line type and a cofactor matrix having N × N cofactors arranged in a matrix type; And extracting the digital touch data by the size of the selected cofactor matrix, matching and multiplying the cofactors and the digital touch data by 1: 1, and amplifying the digital touch data by summing the results. .

When amplifying digital touch data located at corners and edges of the touch screen, the dummy data is selected as data outside the touch screen, and the dummy data is multiplied by a cofactor factored in an area outside the touch screen. The multiplication result is summed with other multiplication results.

The cofactors include a maximum value set at the center of the cofactor matrix and a minimum value set at corners and edges of the cofactor matrix.

Cofactors set between the maximum value and the minimum value have a higher value as the position is closer to the maximum value and a lower value as the position is closer to the minimum value.

The present invention amplifies digital touch data obtained from touch sensors using cofactors arranged in a line type or cofactors arranged in a matrix type, and amplifies the output of a touch sensor located at a corner or an edge of a touch screen. When the dummy data to be calculated in the cofactor is added, the output of all touch sensors constituting the touch screen can be amplified, thereby removing high frequency noise components.

1 is a block diagram illustrating a display device according to an exemplary embodiment of the present invention.
2 to 4 are views showing various embodiments of a touch screen and a display panel.
5 is a cross-sectional view illustrating an example of a display panel in which touch sensors are built as shown in FIG. 4.
FIG. 6 is a circuit diagram illustrating a sampling switch and an amplifier of the touch sensor read circuit illustrated in FIG. 1.
7 is a flowchart illustrating a method of amplifying an output signal of a touch sensor according to an exemplary embodiment of the present invention.
FIG. 8 illustrates a method of amplifying digital touch data using an example of a cofactor matrix.
9 illustrates a method of amplifying digital touch data using another example of the cofactor matrix.
FIG. 10 is a diagram illustrating a three-dimensional graph of the digital touch data amplification result RES of FIG. 9.
11 to 14 are diagrams showing experimental results of amplifying digital touch data by varying cofactor matrix shapes.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Like reference numerals throughout the specification denote substantially identical components. In the following description, when it is determined that a detailed description of known functions or configurations related to the present invention may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

1 to 4, a display device according to an exemplary embodiment of the present invention includes a display driving circuit for writing video data to pixels of a display panel DIS and a display panel DIS including a pixel array and a touch screen. A timing sensor 20, a touch sensor read-out circuit 16 for reading outputs of touch sensors of the touch screen, a touch sensor output amplification circuit 18, a memory 22, and a touch The coordinate calculation part 24 is included.

The display driver circuit includes a display data driver circuit 12 and a display scan driver circuit 14. The display driving circuit sequentially writes the video data voltage into the pixels one horizontal line for one frame period.

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), and electrophoretic display devices (Electrophoresis, EPD). The flat panel display device is provided with a touch screen as shown in FIGS. 2 to 4. In the following embodiments, as an example of a flat panel display element, a liquid crystal display element is described, but it should be noted that the display device of the present invention is not limited to the liquid crystal display element.

In the display panel DIS, a liquid crystal layer is formed between two glass substrates. The lower substrate of the display panel DIS includes a plurality of data lines D1 to Dm and m is a positive integer, and a plurality of gate lines G1 to Gn intersecting the data lines D1 to Dm are positive. ), A plurality of TFTs formed at intersections of the data lines D1 to Dm and the gate lines G1 to Gn, and a plurality of pixels for charging data voltages to liquid crystal cells. And a storage capacitor connected to the electrode and the pixel electrode to maintain the voltage of the liquid crystal cell.

The pixels of the display panel DIS are formed in a pixel area defined by the data lines D1 to Dm and the gate lines G1 to Gn, and are arranged in a matrix form. Each liquid crystal cell of the pixels is driven by an electric field applied according to a voltage difference between a data voltage applied to the pixel electrode and a common voltage applied to the common electrode to control the amount of incident light. The TFTs are turned on in response to gate pulses from the gate lines G1 to Gn to supply a voltage from the data lines D1 to Dm to the pixel electrodes of the liquid crystal cell. The common electrode is formed on the upper glass substrate in a vertical electric field driving method such as twisted nematic (TN) mode and vertical alignment (VA) mode, and a horizontal electric field driving such as IPS (In Plane Switching) mode and FFS (Fringe Field Switching) mode. The pixel electrode is formed on the lower substrate.

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 the COT structure, the black matrix and the color filter may be formed on the lower substrate of the display panel DIS.

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

A backlight unit may be disposed on the back surface of the display panel DIS. The backlight unit is implemented as an edge type or direct type backlight unit to emit light to the display panel DIS.

The display data driver circuit 12 includes a plurality of source drive integrated circuits (ICs). Source drive ICs include a shift register, latch, digital-to-analog converter (DAC), an output buffer, and the like. The source drive ICs latch the digital video data RGB input from the timing controller 20. The source drive ICs convert the digital video data (RGB) into analog positive / negative gamma compensation voltages and output analog video data voltages. The analog video data voltage is supplied to the data lines D1 to Dm.

The display scan drive circuit 14 includes one or more scan drive ICs. The scan drive IC includes a level shifter, a shift register, and the like. The scan drive IC sequentially supplies gate pulses (or scan pulses) synchronized with the analog video data voltages to the gate lines G1 to Gn under the control of the timing controller 20 to write the analog video data voltages. DIS) line is selected one by one.

The timing controller 20 receives timing signals such as a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a data enable signal Data Enable, and a main clock MCLK input from an external host system. Display timing control signals for controlling the operation timing of the display data driver circuit 12 and the display scan driver circuit 14 are generated. The timing control signal of the display scan driving circuit 14 includes a gate start pulse (GSP), a gate shift clock (GSC), a gate output enable signal (Gate Output Enable, GOE), and the like. . The timing control signal of the display data driver circuit 12 includes a source sampling clock (SSC), a polarity control signal (Polarity, POL), a source output enable signal (Source Output Enable, SOE), and the like.

The timing controller 20 generates Rx timing control signals Rxcon for controlling the operation timing of the touch sensor read circuit 16. The Rx timing control signal Rxcon includes a touch sensor output sampling timing control signal of the touch sensor read circuit 16, an analog to digital converter (ADC) clock, and the like.

The touch sensors TS of the touch screen may be stacked on the upper polarizer POL1 of the display panel DIS as shown in FIG. 2, or may be formed between the upper polarizer POL1 and the upper glass substrate GLS1 as shown in FIG. 3. Can be. The touch sensors TS may be formed on the lower substrate in an in-cell type together with a pixel array in the display panel DIS as shown in FIG. 4. 2 to 4, "PIX" denotes a pixel electrode of a liquid crystal cell, "GLS2" denotes a lower substrate, and "POL2" denotes a lower polarizing plate, respectively. Output terminals of the touch sensors TS are connected to input terminals of the touch sensor read circuit 16 through Rx lines R1 to Ri.

The touch sensor read circuit 16 sequentially reads outputs of the touch sensors formed on the touch screen in response to the Rx timing control signal Rxcon. The touch sensor reading circuit 16 samples and amplifies analog outputs of touch sensors input through the Rx lines R1 to Ri. The touch sensor reading circuit 16 converts the analog output into digital touch data using an ADC and transmits the analog output to the touch sensor output amplifying circuit 18.

The touch sensor output amplifying circuit 18 reads cofactors and dummy data from the memory 22. The cofactors are values of a Cofacor matrix of a preset window size, which are 1: 1 matched and multiplied with digital data of each touch sensor. The dummy data (DUM of FIGS. 8 and 9) is applied as virtual data outside the touch screen when amplifying the digital data of the touch sensors located at the corner or edge of the touch screen, and may be set to '0'.

The touch sensor output amplifying circuit 18 maps the cofactors 1: 1 with the digital touch data obtained from each of the touch sensors, multiplies the values (multiplies), sums the multiplication results, and calculates the touch sensor output. Amplify. The touch sensor output amplification circuit 18 shifts the cofactor matrix by one touch sensor in order for all touch sensor outputs of the touch screen to be calculated with the cofactor, and performs the calculation process of the cofactor and digital touch data as described above. Repeat for the touch sensors.

The memory 22 stores cofactors set in the cofactor matrix, window size indicating the size of the cofactor matrix, dummy data, and the like. The memory 22 supplies the stored data to the touch sensor output amplifying circuit 18 at the request of the touch sensor output amplifying circuit 18.

The touch coordinate calculator 24 analyzes the digital touch data amplified by the touch sensor output amplifying circuit 18 by using a preset touch recognition algorithm to calculate coordinate values for touch data of a predetermined reference value or more. The coordinate value data of the touch position output from the touch coordinate calculator 24 is transmitted to an external host system as touch digital touch data in HID format. The host system executes an application program associated with the coordinate value of the touch position.

FIG. 5 is a cross-sectional view illustrating an example of a display panel DIS in which touch sensors are embedded as shown in FIG. 4.

Referring to FIG. 5, when the touch sensors TS are embedded in the display panel DIS, the touch sensors TS may have a variable capacitance in which a capacitance value is changed when the upper substrate is pressed by a finger or a pen. It includes. The variable capacitance may be implemented as the auxiliary liquid crystal cell Clc whose thickness G1 varies when the upper substrate GLS1 is pressed by a finger or a pen.

When the touch sensors TS of the touch screen are embedded in the display panel DIS as shown in FIGS. 4 and 5, the cell gap of the liquid crystal cell is between the upper substrate GLS1 and the lower substrate GLS2 of the display panel DIS. In addition to the column spacer CS2 for holding the CG, the auxiliary column spacer CS1 and the depression limit column spacer CS3 for forming the variable capacitance Clc of the touch sensors may be further formed. The depression limiting column spacer CS3 serves as a stopper for limiting the depth to which the upper substrate GLS1 is pressed.

The height (or thickness) of the column spacer CS2 is higher than the height of each of the auxiliary column spacer CS1 and the depression restriction column spacer CS3. The height (or thickness) of the depression limiting column spacer CS3 is lower than the column spacer CS2 and higher than the auxiliary column spacer CS1 and the respective heights.

The touch sensors TS are disposed on the upper substrate GLS1 to cover the auxiliary column spacer CS1, and the lower substrate facing the upper electrode E1 with the variable capacitance Clc therebetween. It further includes an electrode E2. The lower electrode E2 is connected to the input terminal of the touch sensor read circuit 16 through the Rx lines R1 to Ri. The upper electrode E1 may be implemented as a common electrode to which a common voltage (Vcom of FIG. 6) is supplied. The upper electrode E1 is formed on the surface of the auxiliary column spacer CS1 to form the variable capacitance Clc, but the column spacer CS2 and the depression limiting column are prevented so that the upper substrate and the lower substrate are not short circuited. It is not formed on the surface of the spacer CS3.

6 is a circuit diagram illustrating a sampling switch and an amplifier of the touch sensor read circuit 16.

Referring to FIG. 6, the touch sensor read circuit 16 includes first and second sampling switches SW1 and SW2, an amplifier AMP, a reference voltage charging capacitor Cref, and the like. The first sampling switch SW1 connects the voltages of the Rx lines R1 to Ri to the discharge voltage source Va under the control of the timing controller 20, thereby determining the voltages of the Rx lines R1 to Ri by the reference voltage Vref. Initialize to). The second sampling switch SW2 connects the Rx lines R1 to Ri to the charging voltage source Vb under the control of the timing controller 20 to thereby control the voltages of the Rx lines R1 to Ri above the reference voltage Vref. Charge with. The reference voltage charging capacitor Cref supplies the reference voltage Vref to the Rx lines R1 to Ri. The amplifier AMP is implemented as an operational amplifier (OP amp) and amplifies a change in the touch sensor output supplied through the Rx lines R1 to Ri to an ADC (not shown).

7 is a flowchart illustrating a method of amplifying an output signal of a touch sensor according to an exemplary embodiment of the present invention. The output signal amplification method of the touch sensor is processed by the touch sensor output amplification circuit 18. A method of amplifying the output signal of the touch sensor will be described with reference to FIGS. 8 to 10.

7 to 10, the memory 22 stores cofactors set in the cofactor matrix, window size indicating the size of the cofactor matrix, dummy data, and the like.

The cofactor matrix includes 1 (row direction) × N (column direction, N is an odd number of 3 or more) cofactors as shown in FIG. 8 or N (row direction) × N (column direction) cofactors as shown in FIG. 9. It can be set to include size. The cofactors include a maximum value set at the center of the cofactor matrix and a minimum value set at the corner and edge portions of the cofactor matrix. Cofactor values set between the maximum value and the minimum value have a higher value as the position is closer to the maximum value at the center, and lower as the position is closer to the minimum value at the corner / edge part. Therefore, the cofactor matrix has a maximum value set in the center thereof, and a value is lower as it is farther from the maximum value.

In the example of FIG. 8, the cofactor matrix discloses an example including 1 × 5 cofactors, but is not limited thereto. For example, the cofactor matrix of FIG. 8 may be set to a size containing 1 × 3 cofactors or to a size including 1 × 7 cofactors. In the example of FIG. 9, the cofactor matrix discloses an example including 5 × 5 cofactors, but is not limited thereto. For example, the cofactor matrix of FIG. 9 may be set to a size including 3 × 3 cofactors or to a size including 7 × 7 cofactors.

The output signal amplification method of the touch sensor scans the touch screen line by line to read the output of the touch sensors line by line, converts the output into digital touch data, and stores the output in the memory 22. If the digital touch data to be amplified is data obtained from touch sensors located at corners or edges of the touch screen, the digital signal to amplify the preset dummy data DUM as shown in FIGS. 8 and 9. Add to the left or right side of the data. (S1 and S2) The reason for adding the dummy data DUM is cofactor and calculation when amplifying the digital touch data of the touch sensor located at the corner and edge of the touch screen. This is to prevent malfunction of cofactor calculation process because there is no data that can be done.

The output signal amplification method of the touch sensor extracts window data defined by the window size from the digital touch data (S3). The window size is equal to the size of the cofactor matrix. The window data includes as much digital touch data as cofactors of the cofactor matrix and includes digital touch data to be amplified at the center thereof.

The output signal amplification method of the touch sensor matches the digital touch data of the extracted window data 1: 1 with the cofactors, multiplies the digital data and the cofactor, and adds the results to the digital touch data positioned at the center of the window data. Amplify (S4 and S5)

When the window data IN extracted from the outputs of the touch sensors is [0 2 3 0 0] as shown in FIG. 8 and the cofactors COF of the cofactor matrix are [1 2 3 2 1], the cofactor matrix The amplification result of the digital data located at the center of X is (1x0) + (2x2) + (3x3) + (2x0) + (1x0) = 13. If the window data IN extracted from the outputs of the touch sensors and the cofactors COF of the cofactor matrix are shown in FIG. 9, the amplification result of the digital data located at the center of the cofactor matrix is (8 × 2) + ( 6x2) + (6x2) + (5x3) = 55. FIG. 10 is a diagram illustrating a three-dimensional graph of the digital touch data amplification result RES of FIG. 9.

The output signal amplification method of the touch sensor amplifies all touch sensor outputs of the touch screen by repeating steps S0 to S5 while moving the cofactor matrix by one touch sensor.

11 to 14 are diagrams showing experimental results of amplifying digital touch data by varying cofactor matrix shapes. 11 is raw data obtained from touch sensors. Raw data is digital touch data before it is computed with the cofactor. In FIG. 11, the vertical axis is the value of raw data and the maximum value of the touch sensor touched in the raw data is '30'.

In order to exclude the effect of the cofactor value and to verify the data amplification effect according to the cofactor matrix shape, the cofactors of the 1 × 5 cofactor matrix and the 3 × 3 cofactor matrix used in the experiment were All are set to '1'. 12 is a result of amplifying the raw data of FIG. 11 using a 1 × 5 cofactor matrix, and FIG. 13 is a result of amplifying the raw data of FIG. 11 using a 3 × 3 cofactor matrix. In FIG. 12, the vertical axis is a value of amplified digital touch data, and a maximum value of the touch sensor touched among the digital touch data is '105'. In FIG. 13, the vertical axis is the value of the amplified digital touch data, and the maximum value of the touch sensor touched among the digital touch data is '208'.

As can be seen in the comparison of FIGS. 12 and 13, the touch sensor touched when amplifying the digital touch data using matrix type cofactors such as N × N compared to line type cofactors such as 1 × N. The amplification effect is greater. Also, when amplifying digital touch data using matrix type cofactors such as N × N, the difference between the touch sensor output and the non-touch touch sensor output is larger than that of the line type cofactors such as 1 × N. .

FIG. 14 illustrates images obtained by converting the amplification result of FIG. 12 and the amplification result of FIG. 13 into gray video data and displaying them on the display panel DIS. As can be seen in FIG. 14, when amplifying digital touch data using matrix type cofactors such as N × N, the low pass filtering effect is greater than that of line type cofactors such as 1 × N. More noise components can be removed.

As shown in the experimental results of FIGS. 11 to 14, the present invention can amplify the output of the touch sensors sufficiently high using line type or matrix type cofactors, and remove high frequency noise mixed in the touch sensor output. It is possible to increase the sensitivity of the touch screen and to prevent malfunction of the touch screen. The shape or cofactor values of the cofactor matrix may be selected depending on the application to which the touch screen is applied.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the present invention should not be limited to the details described in the detailed description, but should be defined by the claims.

DIS: Display Panel TS: Touch Sensor
12: display data drive circuit 14: display scan drive circuit
16: touch sensor readout circuit 18: touch sensor output amplification circuit
20: timing controller 22: memory
24: touch coordinate calculation unit

Claims (4)

A touch screen including a plurality of touch sensors;
A touch sensor reading circuit converting an output of each of the touch sensors into digital touch data; And
From each of the touch sensors using either a cofactor matrix having 1 × N (N is an odd number of 3) cofactors arranged in a line type and a cofactor matrix having N × N cofactors arranged in a matrix type. A touch sensor output amplifying circuit for amplifying the obtained digital touch data,
The touch sensor output amplifying circuit extracts the digital touch data by the size of the cofactor matrix, matches the cofactors and the digital touch data by 1: 1, multiplies them, and adds the results to add the digital touch data. Amplify,
The touch sensor output amplifying circuit selects preset dummy data as data outside the touch screen when amplifying digital touch data located at corners and edges of the touch screen, and is arranged in an area outside the touch screen. And multiplying the dummy data by and adding the multiplication result with other multiplication results. The method of claim 1,
The cofactors include a maximum value set at the center of the cofactor matrix, a minimum value set at corners and edges of the cofactor matrix,
The cofactors set between the maximum value and the minimum value have a higher value as the position is closer to the maximum value, and a lower value as the position is closer to the minimum value. Converting the output of each of the touch sensors into digital touch data;
Setting one of a cofactor matrix having 1 × N (N is an odd number of 3) cofactors arranged in a line type and a cofactor matrix having N × N cofactors arranged in a matrix type; And
Extracting the digital touch data by the size of the selected cofactor matrix, matching and multiplying the cofactors and the digital touch data by 1: 1, and amplifying the digital touch data by summing the results;
When amplifying digital touch data located at corners and edges of the touch screen, the dummy data is selected as data outside the touch screen, and the dummy data is multiplied by a cofactor factored in an area outside the touch screen. And multiplying the multiplication result with other multiplication results. The method of claim 3, wherein
The cofactors include a maximum value set at the center of the cofactor matrix, a minimum value set at corners and edges of the cofactor matrix,
The cofactors set between the maximum value and the minimum value have a higher value as the position is closer to the maximum value, and a lower value as the position is closer to the minimum value.

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