KR20140139873A - Touch sensing system and enhancement method of touch report rate thereof - Google Patents

Abstract

The present invention relates to a touch sensing system and a method for improving the touch report rate, and more particularly, to a touch sensing system that applies driving signals to touch sensors and outputs real touch input coordinate data obtained from the touch sensors and virtual touch input coordinate data obtained by an interpolation method And a touch-screen drive circuit. The touch screen driving circuit repeatedly outputs the first touch input coordinate data immediately after the first touch input or outputs interpolated data calculated based on data of other buffers excluding the data of the buffer in which the NULL value is stored, Output a null value.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a touch sensing system and a method for enhancing the touch report rate of the touch sensing system.

The present invention relates to a touch sensing system and a method for improving the touch report rate.

A user interface (UI) enables a user (a user) to communicate with various electric or electronic devices, allowing the user to 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 functions. User interface technology has been developed to enhance the user's sensibility and ease of operation. Recently, the user interface has evolved into a touch UI, a voice recognition UI, a 3D UI, and the like.

Touch UI is becoming a necessity for portable information devices and is being applied to household appliances. The touch sensing system of the capacitive type has advantages in that the structure of the touch screen is higher in durability and sharpness than the conventional resistive film type, and can be applied to various applications because multi-touch recognition and proximity touch recognition are possible. In such a touch sensing system, it is necessary to increase the touch report rate in order to increase the touch sensed by the user and correctly recognize the touch input trajectory or the dragging trajectory. The touch report rate refers to a speed or frequency (Hz) at which coordinate information of touch data obtained by sensing touch sensors in a touch screen is transmitted to an external host system.

The touch sensors may be embedded in the cell array of the display device as an in-cell. In this case, since the touch sensor and the circuits of the pixel array are close to each other, the touch sensing signal is greatly influenced by the display driving signal. Accordingly, in order to temporally separate the touch signal and the display driving signal from the display device having the touch sensor in the in-cell type, one frame period (T) is divided into a display period (Td) and a touch sensing period (Ts) It is time-sharing.

In Fig. 1, "Vsnc" is a vertical synchronization signal. The "display drive" is a display period (Td) in which the pixel arrays of the display panel are driven in a high logic section. The "TSP drive" represents the touch sensing period Ts during which the touch sensors of the touch screen panel are driven. S (n-1) is a driving signal applied to the touch sensors during the touch sensing period Ts of the n-th (n is a positive integer) -1 frame period. S (n) is a driving signal applied to the touch sensors during the touch sensing period Ts of the n-th frame period. A touch screen driving circuit (not shown) applies a driving signal to touch sensors during a touch sensing period (Ts), senses the amount of charge change of the touch sensor in synchronization with the driving signal, (Touch raw data). The touch screen driving circuit executes a preset touch recognition algorithm to analyze the touch source data to calculate the coordinates of the touch input position. In Fig. 1, "TSP coordinate calculation" indicates a timing at which touch input coordinates are calculated. C (n-1) is n-1-th touch input coordinate data obtained in the n-1-th frame period, and C (n) is n-th touch input coordinate data obtained in the n-th frame period. The touch screen drive circuit transmits the touch input coordinates to the external host system once in one frame period (T). In Fig. 1, "Coordinate Report" is a touch report rate. Therefore, since the conventional touch sensing system reports touch coordinate data once in one frame period, the touch report rate can not be made faster than 100 Hz.

The present invention provides a touch sensing system capable of increasing a touch report rate and a method for improving the touch report rate.

The touch sensing system of the present invention includes a touch screen driving circuit for applying driving signals to touch sensors and outputting real touch input coordinate data obtained from the touch sensors and virtual touch input coordinate data obtained by an interpolation method.

The touch screen driving circuit repeatedly outputs the first touch input coordinate data immediately after the first touch input or outputs interpolated data calculated based on data of other buffers excluding the data of the buffer in which the NULL value is stored, Output a null value.

The method of improving the touch report rate of the touch sensing system includes applying a driving signal to the touch sensors, outputting the real touch input coordinate data obtained from the touch sensors and the virtual touch input coordinate data obtained by the interpolation method.

The first touch input coordinate data is repeatedly output immediately after the first touch input or the interpolated data calculated based on the data of the buffers other than the data of the buffer where the NULL value is stored is output or the null value is output.

The present invention can increase the touch report rate of a touch sensing system by generating real touch input data obtained from a touch sensor and virtual touch data calculated by an interpolation method. Further, the present invention may be modified such that the first touch input coordinate data is repeatedly output immediately after the initial touch input, or the interpolated data calculated based on the data of the buffers other than the data of the buffer where the NULL value is stored is output, The difference in distance between the actual touch position and the touch position displayed on the screen can be minimized when the first touch input is performed.

1 is a waveform diagram showing a display period, a touch sensing period, a touch input coordinate calculation timing, and a transmission timing of a touch input coordinate in a conventional touch sensing system.
2 is a diagram illustrating a touch sensing system according to an embodiment of the present invention.
3 is an equivalent circuit diagram of the touch screen shown in FIG.
4 to 6 are views showing various combinations of the display panel and the touch screen.
FIGS. 7 and 8 are waveform diagrams showing display periods, touch sensing periods, touch input coordinate operation timings, and transmission timings of touch input coordinates in the touch sensing system according to the embodiment of the present invention.
9 is a diagram illustrating an example of an initial touch input error.
10 is a diagram showing an interpolation data generating circuit.

The display device of the present invention can be applied to a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), an organic light emitting display , OLEDs, and electrophoresis (EPD) devices. In the following embodiments, a display device is described as a liquid crystal display device 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.

The touch sensing system of the present invention can be implemented as a capacitive touch screen that senses a touch input through a plurality of capacitive sensors. The capacitive touch screen includes a plurality of touch sensors. Each of the touch sensors includes a capacitance in terms of an equivalent circuit. Capacitance can be divided into self capacitance or mutual capacitance. The self-capacitance is formed along a conductor wiring of a single layer formed in one direction. The mutual capacitance is formed between two orthogonal conductor wirings. In the following embodiments, mutual capacitance type touch screens are exemplified, but are not limited thereto.

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, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

2 to 6, a display device according to an exemplary 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) has a liquid crystal layer formed between two substrates. The pixel array of the display panel DIS includes pixels formed in the pixel region defined by the data lines (D1 to Dm, m is a positive integer) and the gate lines (G1 to Gn, n is a positive integer) . Each of the pixels is connected to TFTs (Thin Film Transistors) formed at intersections of the data lines D1 to Dm and the gate lines G1 to Gn, a pixel electrode for charging a data voltage, A storage capacitor (Cst) for maintaining the voltage, and the like.

A black matrix, a color filter and the like are formed on the upper substrate of the display panel DIS. The lower substrate of the display panel DIS may be implemented with a COT (Color Filter On TFT) structure. In this case, the black matrix and the color filter can be formed on the lower substrate of the display panel DIS. The common electrode to which the common voltage is supplied may be formed on the upper substrate or the lower substrate of the display panel DIS. On the upper substrate and the lower substrate of the display panel DIS, a polarizing plate is attached, and an alignment film for forming a pre-tilt angle of the liquid crystal on the inner surface in contact with the liquid crystal is formed. 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 below the rear surface of the display panel DIS. The backlight unit is implemented as an edge type or direct type backlight unit, and irradiates the display panel (DIS) with light. The display panel DIS may be implemented in any known liquid crystal mode such as TN (Twisted Nematic) mode, VA (Vertical Alignment) mode, IPS (In Plane Switching) mode and FFS (Fringe Field Switching) mode.

The display driving circuit includes a data driving circuit 12, a gate driving circuit 14, and a timing controller 20, and writes the data of the input image to the pixels of the display panel DIS. The data driving circuit 12 converts the digital video data RGB input from the timing controller 20 into an analog positive / negative gamma compensation voltage to output a data voltage. The data voltage output from the data driving circuit 12 is supplied to the pixels through the data lines D1 to Dm. The gate drive circuit 14 sequentially supplies a gate pulse (or a 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 data is written.

The timing controller 20 inputs a timing signal 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 And synchronizes the operation timings of the data driving circuit 12 and the gate driving circuit 14 with each other. The gate timing control signal includes a gate start pulse (GSP), a gate shift clock, a gate output enable signal (GOE), and the like. The data timing control signal includes a source sampling clock (SSC), a polarity control signal (Polarity), a source output enable signal (SOE), and the like.

The touch screen TSP includes Tx lines (T1 to Tj, j is a positive integer less than n), Rx lines (R1 to Ri, i being an amount less than m) crossing the Tx lines And MxN touch sensors Cts formed at intersections of the Tx lines T1 to Tj and the Rx lines R1 to Ri. Each of the touch sensors Cts includes mutual capacities. The touch screen TSP may be bonded onto the upper polarizer POL1 of the display panel DIS as shown in FIG. 4 or may be formed between the upper polarizer POL1 and the upper substrate GLS1 as shown in FIG. In addition, the touch sensors Cts of the touch screen TSP may be embedded on the lower substrate in an in-cell type together with the pixel array in the display panel DIS as shown in FIG. 4 to 6, "PIX" means a pixel electrode of a liquid crystal cell, "GLS2" means a lower substrate, and "POL2" means a lower polarizer. FIGS. 7 and 8 illustrate embodiments of the present invention applied to an in-cell type touch sensing system, but the present invention can be applied to a touch sensing system of any structure.

The touch screen driving circuit 30 includes a touch sensing driving circuit and a touch screen controller 36 (hereinafter referred to as a "TSP controller"). The touch sensing driving circuit includes a Tx driving circuit 32 and an Rx driving circuit 34. [ The touch sensing driver circuit applies a driving signal to the touch sensors through the Tx lines T1 to Tj using the Tx driving circuit 32 and applies the driving signals to the Rx lines R1 to Ri and the Rx driving circuit And senses the voltage of the touch sensors Cts through the line 34 to output touch raw data as digital data. The driving signal can be generated in various forms such as a pulse, a sinusoidal wave, and a triangular wave. The touch screen drive circuit 30 can be integrated into one ROIC (Read-out IC).

The Tx driving circuit 32 selects a Tx channel to output the Tx driving signal in response to the Tx set-up signal input from the TSP controller 36 and supplies the Tx driving signal Tx to the Tx lines T1 to Tj connected to the selected Tx channel . The Tx lines T1 to Tj are charged during the high potential section of the Tx driving signal to supply charges to the touch sensors Cts and are discharged in the low potential section of the Tx driving signal. The Tx driving signal is supplied to the Tx lines T1 to Tj so that the voltage of the touch sensors Cts can be accumulated in the capacitors of the integrator built in the Rx driving circuit 34 through the Rx lines R1 to Ri. ), Respectively.

The Rx driving circuit 34 selects the Rx lines R1 to Ri to receive the voltage of the touch sensor in response to the Rx set-up 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 Ri in synchronization with the driving signal applied to the touch sensor and accumulates them in the integrator. The Rx driving circuit 34 converts the voltage accumulated in the integrator into digital raw data, which is digital data, using an analog-to-digital converter (ADC) connected to the output terminal of the integrator.

The TSP controller 36 receives a Tx setup signal for setting the Tx channel to output the Tx driving signal in the Tx driving circuit 32 and a Tx setup signal for setting the Rx channel for receiving the voltage of the touch sensors Cts in the Rx driving circuit 34. [ So that the sensing operation of the Tx driving circuit 32 and the Rx driving circuit 34 is synchronized. Further, the TSP controller 36 generates a switch control signal for controlling the operation timing of the sampling and integrator of the Rx driving circuit 34 and an ADC clock signal for controlling the operation timing of the ADC. The TSP controller 36 may be implemented as an MCU (Micro Controller Unit).

The TSP controller 36 executes a preset touch recognition algorithm to compare the real touch raw data received from the Rx driving circuit 34 with a preset threshold value. The touch recognition algorithm detects real touch raw data above a threshold value. The real-touch source data is judged as real-touch data obtained from the touch sensors in which the touch input is generated. The TSP controller 36 applies driving signals to the touch sensors and outputs the real touch input coordinate data obtained from the touch sensors and the virtual touch input coordinate data obtained by the interpolation method. The TSP controller 36 outputs the first virtual touch input coordinate data between the first real touch input coordinate data and the second real touch input coordinate data and outputs the second real touch input coordinate data and the third real touch input coordinate data And outputs the second virtual touch input coordinate data.

The TSP controller 36 executes the touch recognition algorithm to calculate the real touch input coordinate data and transmits the coordinate data to the host system 40. [ Also, the TSP controller 36 generates virtual touch input coordinate data calculated by the interpolation method regardless of the sensing results of the touch sensors, and transmits the virtual touch input coordinate data to the host system 40. The TSP controller 36 can generate the virtual touch data using the interpolation data generating circuit as shown in FIG. The interpolation data generation circuit receives past real touch input coordinate data or virtual touch input coordinate data, multiplies the data by a preset proportional constant, and outputs an output obtained by adding the results to virtual touch input coordinate data. Accordingly, the present invention can transmit the coordinate information of the real-touch data and the virtual-touch data to the host system 40, thereby making the touch-report rate two times faster than that of the related art. The touch report rate of the present invention can realize a touch report rate that is two times higher than the frame rate of the input image. The frame rate of the input image is 60 Hz in the National Television Standards Committee (NTSC) system and 50 Hz in the PAL (Phase-Alternating Line) system.

The host system 40 may be implemented in any one of a television system, a set-top box, a navigation system, a DVD player, a Blu-ray player, a personal computer (PC), a home theater system, and a phone system. The host system 40 includes a system on chip (SoC) with a built-in scaler to convert the digital video data RGB of the 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 to the timing controller 20 together with the digital video data. The host system 40 also executes an application program associated with coordinate information XY of the touch data input from the TSP controller 36. [

FIGS. 7 and 8 are waveform diagrams showing display periods, touch sensing periods, touch input coordinate operation timings, and transmission timings of touch input coordinates in the touch sensing system according to the embodiment of the present invention. 7 and 8, "Vsnc" is a vertical synchronization signal. The "display drive" is a display period (Td) in which the pixel arrays of the display panel are driven in a high logic section. "TSP drive" represents a touch sensing period (Ts) in which the touch sensors are driven. S (n-1) is a driving signal applied to the touch sensors during the touch sensing period Ts of the n-th (n is a positive integer) -1 frame period. S (n) is a driving signal applied to the touch sensors during the touch sensing period Ts of the n-th frame period. The "TSP coordinate calculation" indicates the timing at which the touch input coordinates are calculated. In Fig. 1, "Coordinate Report" is a touch report rate. (N-3) is the (n-3) th touch input coordinate data obtained in the (n-3) th frame period and C to be. C (n-1) is the (n-1) -th touch input coordinate data obtained in the (n-1) -th frame period. C (n) is the n-th real touch input coordinate data obtained in the n-th frame period.

The touch sensing system of the present invention calculates virtual touch input coordinates using real touch input data and calculates virtual touch input coordinate data C '(n-2, n-3), C' (n -1, n-2) and C '(n, n-1) to the host system 40. The touch sensing system of the present invention can control the transmission timing of the interpolation data by using a timer built in the touch screen driving circuit 30. [ The touch screen drive circuit 30 generates the virtual touch input coordinate data C '(n-2, n-3), C' (n (n) -1, n-2), C '(n, n-1)) to the host system. (N-2) and the (n-2) th touch input coordinate data C (n-2, n-3) The first virtual touch input coordinate data transmitted between the first virtual touch input coordinate data and the second virtual touch input coordinate data. (N-1) and the (n-2) -th real touch input coordinate data C (n-1) The second virtual touch input coordinate data transmitted between the transmission timings of the virtual touch input coordinates. Between the transfer timing of the (n-1) th real touch input coordinate data C (n-1) and the transfer timing of the nth real touch input coordinate data C (n) And the third virtual touch input coordinate data to be transmitted.

The real / virtual touch input data is composed of a valid code indicating the presence or absence of effective coordinate data and a data packet including coordinate information of the touch input position. The host system 40 determines that there is no current touch input when a data packet in which the null value is coded in the valid code is received from the touch screen driving circuit 30, The coordinate information included in the data packet input subsequent to the valid code is determined to be valid information.

When the virtual touch input coordinate data is output immediately after the first touch input, as shown in FIG. 9, since the error between the actual touch position and the virtual touch input coordinate is relatively large, the distance between the actual touch position and the touch position displayed on the screen becomes farther, Can be degraded. This is because the buffers for storing the previous touch input coordinate data are initialized to null data. The initial touch input means a touch input that is first recognized after the power is input to the touch sensing system and the display driving circuit and the touch screen driving circuit 30 are initialized. In order to minimize the difference in distance between the actual touch position and the touch position displayed on the screen when the first touch input is performed, the first real touch input coordinate data may be repeatedly output one more time as shown in FIG. In FIG. 8, C (n-2) is an example of the initial touch input coordinate data that is repeatedly transmitted to the host system 40 twice.

Fig. 10 shows an interpolation data generating circuit for generating virtual touch input data.

Referring to FIG. 10, the interpolation data generating circuit includes a plurality of buffers 91a to 91d, a plurality of multipliers 92a to 92c, and a plurality of adders 93a to 93c.

Such an interpolation data generation circuit is constituted by the number of touch inputs capable of being simultaneously received in a touch sensing system that supports multi-touch recognition. For example, the interpolation data generation circuit is implemented for each Touch ID. A system that supports 10 touch inputs requires 10 interpolation data generation circuits capable of parallel processing.

The buffers 91a to 91c are connected in a dependent manner to temporarily store the touch input coordinate data and transmit data to the next stage buffer in every frame period in synchronization with the vertical synchronization signal Vsync to shift the data . The touch input coordinate data may be real touch input coordinate data or virtual touch input coordinate data. The touch input coordinate data may be a combination of real touch input coordinate data and virtual touch input coordinate data. The touch input coordinate data may be real touch input coordinate data or virtual touch input coordinate data. The kth (k is a positive integer) buffer 91a stores the kth touch input coordinate data Xk received by the current input signal Xin and supplies the kth touch input coordinate data Xk to the (k-1) th buffer 91b in the next frame period. Lt; / RTI > The k-1 buffer 91b stores the (k-1) -th touch input coordinate data Xk-1 and transmits the data Xk-1 to the k-2 buffer 91c in the next frame period. The k-2 buffer 91c stores the k-2th touch input coordinate data Xk-2 and transmits the data Xk-2 to the k-3 buffer 91d in the next frame period. The past touch input coordinate data is stored in three buffers 91b to 91d.

The multipliers 92a to 92d multiply the touch input coordinate data by predetermined proportional constants (?,?,?,?). The proportional constants can be set to α + β + γ + δ = 1. The adders 93a to 93c add touch input coordinate data multiplied by a proportional constant.

In the first touch input, a NULL value '0' is stored in the second to fourth buffers 91b to 91d. The interpolation data generation circuit generates the interpolation data from the first to third periodic signals V1 to V3 of the vertical synchronization signal Vsync in order to minimize the difference in distance between the actual touch position and the touch position displayed on the screen at the time of first touch input k touch input coordinate data Xk repeatedly (Xout). This method is substantially the same as in Fig. The interpolation data generation circuit can recognize the first touch input state by determining whether the data stored in the second to fourth buffers 91b to 91d is null data. The interpolation data generation circuit generates a normal output after the fourth periodic signal V4 of the vertical synchronization signal Vsync.

When the data stored in the second to fourth buffers 91b to 91d are all NULL data, the interpolation data generation circuit determines the currently input touch input coordinate data as coordinate data of the first touch input. The interpolation data generation circuit outputs the output as Xout =? Xk +? Xk-1 +? Xk-2 +? Xk-3 when the initial touch input state is not satisfied.

Xout = Xin if, (V1 to V3)

Xout =? Xk +? Xk-1 +? Xk-2 +? Xk-3 (in other cases)

A second method for solving the problem of the difference in distance between the actual touch position and the touch position displayed on the screen at the time of first touch input is to calculate the virtual touch input coordinate data using only data other than the null value immediately after the first touch input Method. This method outputs the input Xin directly from the first periodic signal V1 of the vertical synchronous signal Vsync and outputs the output from the second periodic signal V2 of the vertical synchronous signal Vsync as Xout = +? Xk-1. This method then outputs the output from the third period signal V3 of the vertical synchronizing signal Vsync to Xout =? Xk +? Xk-1 +? Xk-2 and then outputs the fourth period signal of the vertical synchronizing signal Vsync V4), the output is outputted as the normal output method Xout =? Xk +? Xk-1 +? Xk-2 +? Xk-3.

Xout = Xin (V1)

Xout =? Xk +? Xk-1 (? +? = 1, V2)

Xout =? Xk +? Xk-1 +? Xk-2 (? +? +? = 1, V3)

Xout =? Xk +? Xk-1 +? Xk-2 +? Xk-3 (? +? +? +? = 1, V4)

A third method for solving the problem of the distance difference between the actual touch position and the touch position displayed on the screen at the time of first touch input is that the first to third period signals V1 to V3 of the vertical synchronizing signal Vsync ) output a null value (X _nULL) from and to generate a positive power after a fourth period signal (V4) of the k-touch input coordinate data (vertical synchronization signal (Vsync) is Xk) is stored in a fourth buffer (91d) .

Xout = X _NULL (V1 to V3)

Xout =? Xk +? Xk-1 +? Xk-2 +? Xk-3 (in other cases)

The interpolation data generating circuit is not limited to Fig. For example, in the interpolation data generation circuit, the number of buffers for storing past values may be N (N is a positive integer larger than 0), and the proportional constant may be adjusted accordingly.

The interpolation data generating circuit is not limited to Fig. For example, in the interpolation data generation circuit, the number of buffers for storing past values may be N (N is a positive integer larger than 0), and the proportional constant may be adjusted accordingly.

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 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: Gate driving circuit
20: timing controller 30: touch screen driving circuit
32: Tx driving circuit 34: Rx driving circuit
36: TSP controller

Claims (4)

And a touch screen driving circuit for applying driving signals to the touch sensors and outputting the real touch input coordinate data obtained from the touch sensors and the virtual touch input coordinate data obtained by the interpolation method,
The touch screen driving circuit repeatedly outputs the first touch input coordinate data immediately after the first touch input or outputs interpolated data calculated based on data of other buffers excluding the data of the buffer in which the NULL value is stored, And outputs a null value. The method according to claim 1,
Wherein the touch report rate of the touch input coordinate data output from the touch screen driving circuit is higher than the frame rate of the input image. The method according to claim 1,
The touch screen driving circuit
The first virtual touch input coordinate data is output between the first real touch input coordinate data and the second real touch input coordinate data,
And outputs the second virtual touch input coordinate data between the second real touch input coordinate data and the third real touch input coordinate data. A step of applying a driving signal to the touch sensors and outputting the real touch input coordinate data obtained from the touch sensors and the virtual touch input coordinate data obtained by the interpolation method,
Immediately after the initial touch input, the interpolation method repeatedly outputs the first touch input coordinate data, or outputs interpolated data calculated based on data of other buffers except for the data of the buffer in which a null value is stored, And outputting the touch report rate of the touch sensing system.

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