Touch-sensing display device and voltage control method thereof

Abstract

This disclosure relates to a touch-sensing display device and a voltage control method thereof. A touch-sensing display device includes: a clamping circuit comprising a first diode between an input pad and a first terminal receiving a positive clamping voltage, and a second diode between an input pad and a second terminal receiving a negative clamping voltage; an ESD detection circuit connected between the cathode of the first diode and the first terminal and between the cathode of the second diode and the input pad, for detecting whether an AC common signal input through the input pad includes ESD; and a clamping voltage variation circuit configured to vary the range between the positive and negative clamping voltages differently based on whether ESD is detected.

Description

Technical Field

[0001] This disclosure relates to a touch-sensing display device and a voltage control method thereof. Background Technology

[0002] In-cell touch sensor technology, which embeds the touch sensor into the pixel array of a display panel, is known. To reduce electromagnetic interference (EMI) noise, electrostatic discharge (ESD) protection circuitry is incorporated into the input / output (I / O) pads of the touch display driver integrated circuit (TDDI). The ESD protection circuitry protects the display device from ESD by clamping the output waveform using a diode-based clamping circuit.

[0003] The descriptions provided in this Background section should not be assumed to be prior art simply because they are mentioned in or associated with this section. The Background section may include information describing one or more aspects of the subject matter art. Summary of the Invention

[0004] The inventors of this application have newly recognized that, when employing an embedded touch-sensing display device based on, for example, a liquid crystal display (LCD), common voltage ripple can increase proportionally to the swing width of the source output used for inverting drive. Common voltage ripple is an alternating current (AC) frequency component and is used as EMI noise. To reduce common voltage ripple, a common voltage compensation signal with a localized opposite phase should be applied to the display panel. However, compensation voltages in the common voltage compensation signal that are higher than the clamping voltage may be clamped and cut off by clamping circuitry included in the TDDI's I / O pads; therefore, common voltage ripple may not be adequately compensated. Because the clamping voltages of the clamping circuitry are fixed at predetermined high and low voltages, the ranges above the high voltage and below the low voltage in the common voltage compensation signal are output unconditionally, regardless of ESD input.

[0005] To overcome the aforementioned limitations of the related technologies, this disclosure provides a touch-sensing display device and its voltage control method, which can vary the clamping voltage based on whether ESD is detected, and can prevent the common voltage compensation signal from being unconditionally clamped regardless of the ESD input.

[0006] Another aspect of this disclosure is to provide a touch-sensing display device and a voltage control method thereof, which can improve the compensation effect for common voltage ripple, thereby enhancing display quality.

[0007] Additional advantages, aspects, and features of this disclosure will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon reviewing the following, or may be learned from practice of this disclosure. Various aspects and other advantages of this disclosure may be realized and obtained by means of the structures particularly pointed out in the written description and claims, and in the accompanying drawings.

[0008] To achieve these and other aspects, and in accordance with the purposes of this disclosure, as specifically implemented and broadly described herein, a touch-sensing display device includes: a clamping circuit comprising a first diode connected between an input pad and a first voltage terminal receiving a positive clamping voltage, and a second diode connected between the input pad and a second voltage terminal receiving a negative clamping voltage; an electrostatic discharge (ESD) detection circuit connected between the first diode and the first voltage terminal and between the second diode and the input pad to detect whether an AC common signal input through the input pad includes ESD; and a clamping voltage variation circuit configured to vary the range between the positive clamping voltage and the negative clamping voltage differently based on whether ESD is detected, such that a first voltage range between the positive clamping voltage and the negative clamping voltage when ESD is not detected is greater than a second voltage range between the positive clamping voltage and the negative clamping voltage when ESD is detected.

[0009] According to an example embodiment of the present disclosure, the touch-sensing display device and its voltage control method can vary the clamping voltage differently based on whether ESD is detected, and can prevent the common voltage compensation signal from being unconditionally clamped regardless of the ESD input.

[0010] According to an exemplary embodiment of the present disclosure, the touch-sensing display device and its voltage control method can improve the compensation effect for common voltage ripple, thereby enhancing display quality.

[0011] It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory, and are intended to provide further explanation of the claimed disclosure. Attached Figure Description

[0012] The accompanying drawings are included to provide a further understanding of this disclosure and are incorporated in and constitute a part of this application. The drawings illustrate embodiments of the disclosure and, together with the description, serve to explain the various principles of the disclosure. In the drawings:

[0013] Figure 1 This is a diagram illustrating a touch-sensing display device according to an exemplary embodiment of the present disclosure;

[0014] Figure 2 This is a diagram illustrating an example implementation of a touch sensor embedded in a pixel array;

[0015] Figure 3 This is a diagram illustrating an example of how display drivers and touch drivers are separated in time;

[0016] Figure 4 This is a diagram illustrating an example connection between a display panel, a touch display driver integrated circuit (IC) (TDDI), and a common voltage compensation circuit;

[0017] Figure 5 This is a diagram illustrating an example configuration of an electrostatic discharge (ESD) protection circuit that varies the clamping voltage differently based on whether ESD is detected;

[0018] Figure 6 This is a diagram illustrating the detailed connection configuration of the clamping circuit, ESD detection circuit, and clamping voltage change circuit according to an exemplary embodiment of the present disclosure;

[0019] Figure 7 This is a diagram illustrating examples of shifting positive / negative clamping voltages to a first voltage range based on non-ESD detection and shifting positive / negative clamping voltages to a second voltage range based on ESD detection;

[0020] Figure 8 This is a diagram illustrating a detailed configuration of an ESD detection circuit according to an exemplary embodiment of the present disclosure;

[0021] Figure 9 This is a diagram illustrating whether a non-periodic ESD of the touch drive signal is detected during the touch drive period and the subsequent operation according to an exemplary embodiment of the present disclosure;

[0022] Figure 10 This is a diagram illustrating whether an overcurrent ESD compensating for the common voltage is detected during a display driving period and the subsequent operation, according to an exemplary embodiment of the present disclosure;

[0023] Figure 11 This is an example of Figure 9 and Figure 10 A diagram illustrating examples of combinations of cases.

[0024] Throughout the accompanying drawings and detailed description, unless otherwise described, the same reference numerals should be understood to refer to the same elements, features, and structures. For clarity, illustrative purposes, the relative dimensions and illustrations of these elements may be exaggerated. Detailed Implementation

[0025] In the following description, the present disclosure will be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the present disclosure are illustrated. However, the present disclosure may be implemented in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that the disclosure will be thorough and complete and will fully convey the concept of the disclosure to those skilled in the art. Wherever possible, unless otherwise specified, the same reference numerals will be used throughout the drawings to refer to the same or similar parts. The described progression of processing steps and / or operations is exemplary; however, the order of steps and / or operations is not limited to the order set forth herein and may be varied as is known in the art, except for steps and / or operations that need to occur in a particular order. Similar reference numerals refer to similar elements throughout. The names of corresponding elements used in the following description may be chosen solely for ease of writing and may therefore differ from the names used in actual products.

[0026] The advantages and features of this disclosure, and methods of implementing them, will be illustrated by the following exemplary embodiments described with reference to the accompanying drawings. However, this disclosure may be implemented in various forms and should not be construed as limited to the exemplary aspects set forth herein. Rather, these exemplary embodiments are provided so that this disclosure may be thorough and complete, and fully convey the concept of this disclosure to those skilled in the art. Furthermore, this disclosure is limited only by the scope of the appended claims.

[0027] Furthermore, numerous specific details are set forth in the following detailed description of this disclosure in order to provide a sufficiently thorough understanding of this disclosure. However, it will be understood that this disclosure can be practiced without these specific details. In other instances, known methods, processes, components, and circuits have not been described in detail so as not to unnecessarily obscure aspects of this disclosure.

[0028] The shapes, dimensions, ratios, angles, quantities, etc., disclosed in the accompanying drawings used to describe various embodiments of this disclosure are merely exemplary, and this disclosure is not limited thereto. Similar reference numerals refer to similar elements throughout. The same elements are designated by the same reference numerals throughout this specification. As used herein, the terms “comprising,” “having,” “including,” etc., indicate that additional components may be added, unless more restrictive terms such as “only” are used. As used herein, the singular forms “a,” “an,” and “the” are intended to also include the plural forms unless the context clearly indicates otherwise. Any implementation described herein as an “example” is not necessarily to be construed as more preferred or advantageous than other implementations.

[0029] Even if not explicitly stated, the elements in the various embodiments of this disclosure should be interpreted as including margins of error.

[0030] When describing positional relationships, for example, when using terms such as "above," "over," "below," "above," "below," "below," "near," "adjacent," "next to," "beside," or "adjoining" to describe the positional relationship between two components, one or more other components may be located between the two components, unless more restrictive terms such as "immediately," "directly," or "closely" are used. For example, when a structure is described as being "above," "over," "below," "above," "below," "below," "near," "adjacent," "beside," or "adjoining" another structure, this description should be interpreted to include situations where these structures are in contact with each other and situations where a third structure is positioned or inserted between them. Furthermore, the terms "left side," "right side," "top," "bottom," "downward," "upward," "upper part," "lower part," etc., refer to any frame of reference.

[0031] When describing temporal relationships, such as when time sequence is described as “after,” “next,” “next,” and “before,” discontinuous situations may be included unless more restrictive terms such as “only,” “directly,” or “immediately” are used.

[0032] When a component or layer is referred to as being "on" or "connected to" another component or layer, it should be understood that this means the component or layer may be directly on or directly connected to the other component or layer, or that there may be an intermediate component or layer. Furthermore, when a component is referred to as being "on" or "below" another component, it should be understood that this means the components may be configured to be in direct contact with each other, or may be configured not to be in direct contact with each other.

[0033] The term “at least one” should be understood to include any and all combinations of one or more of the relevant listed items. For example, “at least one of the first element, the second element, and the third element” means a combination of all three listed elements, a combination of any two of the three elements, and each individual element, the first element, the second element, or the third element.

[0034] It will be understood that although the terms “first,” “second,” “A,” “B,” “(a),” “(b),” etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another and do not limit the nature, order, sequence, or number of elements. For example, without departing from the scope of this disclosure, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0035] In the following description, detailed descriptions will be omitted where it is determined that such descriptions of known functions or configurations would unnecessarily obscure the essential points of this disclosure. Embodiments of this disclosure will be described in detail below with reference to the accompanying drawings.

[0036] Features of the various embodiments of this disclosure may be partially or wholly linked or combined with each other, and may interoperate with each other and be technically driven in various ways, as will be fully understood by those skilled in the art. Embodiments of this disclosure may be implemented independently of each other, or may be implemented together in an interdependent manner.

[0037] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which the exemplary embodiments pertain. It will also be understood that terms such as those defined in common dictionaries shall be interpreted as having a meaning consistent with, for example, their meaning in the context of the relevant field, and shall not be interpreted as having an overly idealized or overly formal meaning, unless expressly defined herein. For example, the terms “component” or “unit” may be applied, for example, to a single circuit or structure, an integrated circuit, a computational block of a circuit arrangement, or any structure configured to perform the described functions, as would be understood by one of ordinary skill in the art.

[0038] In the following, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Furthermore, all components of each display device according to all embodiments of the present disclosure are operatively connected and configured. For ease of description, the scale of each element shown in the drawings differs from the actual scale; therefore, the description is not limited to the scales shown in the figures.

[0039] Figure 1 This is a diagram illustrating a touch-sensing display device 10 according to an embodiment of the present disclosure. Figure 2 This is a diagram illustrating an implementation of a touch sensor embedded in a pixel array. Figure 3 This is a diagram illustrating an example of how display drivers and touch drivers are separated in time.

[0040] Reference Figures 1 to 3 The touch sensing display device 10 according to the embodiments of the present disclosure can be implemented based on liquid crystal display (LCD), but the present disclosure is not limited thereto, and the touch sensing display device of the present disclosure can also be implemented as an organic light-emitting display device, a quantum dot display device, a micro light-emitting diode (LED) display device or a mini light-emitting diode (LED) display device.

[0041] The touch-sensing display device 10 may be configured with a display module and a touch module.

[0042] The touch module may include a touch screen and a touch driver 18.

[0043] A touchscreen can be implemented as a capacitive type, sensing touch input through multiple capacitive sensors. A touchscreen may include multiple touch sensors or touch electrodes with capacitance. Capacitance can be classified as self-capacitance and mutual capacitance. Self-capacitance can be formed along a single layer of wires formed in one direction, and mutual capacitance can be formed between two wires perpendicular to each other.

[0044] The touch sensor of the touchscreen can be embedded in the pixel array of the display panel PNL. Figure 2 An example of an embedded touchscreen is shown, where the touchscreen is embedded within the pixel array of a display panel (PNL). See reference. Figure 2 The pixel array of the display panel PNL may include touch sensors C1 to C4 and sensor lines L1 to L4 connected to the touch sensors C1 to C4. The common electrode COM of the pixels 101 may be divided into multiple segments. The touch sensors C1 to C4 can be implemented using separate common electrodes COM. A common electrode segment may be connected to multiple pixels 101 and may be configured with one touch sensor.

[0045] like Figure 3 As shown, touch sensors C1 to C4 can provide a common voltage Vcom to pixel 101 during display driving periods Td1 and Td2, and can receive touch driving signal LFD to sense touch input during touch driving periods Tt1 and Tt2. Figure 2 An example of a self-capacitive touch sensor is shown, but touch sensors C1 to C4 are not limited to this.

[0046] The touch driver 18 can drive the touch sensor during touch driving periods Tt1 and Tt2 in response to a touch enable signal TEN input from the timing controller 16 or the host system 19. During touch driving periods Tt1 and Tt2, the touch driver 18 can provide touch drive signals LFD to touch sensors C1 to C4 via sensor lines L1 to Li to sense touch input. The touch driver 18 can sense the capacitance change of the touch sensor before and after a touch to determine touch input via a conductive material such as a finger (or stylus), and can calculate the coordinates of the touch input location. The coordinate information of the touch input location can be transmitted to the host system 19.

[0047] The display module may include a display panel PNL, display driver circuits 12, 14 and 16, and a host system 19.

[0048] The display panel PNL may include a liquid crystal layer formed between two substrates. The pixel array of the display panel PNL may include a plurality of pixels 101 formed in a pixel region defined by data lines D1 to Dm (where m may be a positive integer) and gate lines G1 to Gn (where n may be a positive integer).

[0049] A black matrix and color filter can be formed in the upper substrate of the display panel PNL. The lower substrate of the display panel PNL can be implemented as a TFT upper color filter (COT) structure. In this case, the black matrix and color filter can be formed in the lower substrate of the display panel PNL. A common electrode supplied with a common voltage can be formed in either the upper or lower substrate of the display panel PNL. A polarizer can be attached to each of the upper and lower substrates of the display panel PNL, and an alignment layer for setting the pretilt angle of the liquid crystal can be formed in the inner surface in contact with the liquid crystal. A pillar spacer for maintaining the cell gap of the liquid crystal cell can be formed between the upper and lower substrates of the display panel PNL.

[0050] The backlight unit can be disposed below the rear surface of the display panel PNL. The backlight unit can be implemented as an edge-type or direct-lit backlight unit and can illuminate the display panel PNL. The display panel PNL can be implemented in a liquid crystal mode known to those skilled in the art, such as twisted nematic (TN) mode, vertical alignment (VA) mode, in-plane switching (IPS) mode, or edge field switching (FFS) mode.

[0051] The display driving circuit may include a data driving circuit 12, a gating driving circuit 14, and a timing controller 16, and can write video data of the input image into the pixels 101 of the display panel PNL. The data driving circuit 12 can convert the digital video data RGB input from the timing controller 16 using an analog positive / negative gamma compensation voltage to output a data voltage. The data voltage output from the data driving circuit 12 can be provided to data lines D1 to Dm. The gating driving circuit 14 can sequentially provide gating pulses (or scan pulses) synchronized with the data voltage to gating lines G1 to Gn to select the pixel rows of the display panel PNL in which the data voltage has been written.

[0052] The timing controller 16 can receive timing signals from the host system 19, such as the vertical synchronization signal Vsync, the horizontal synchronization signal Hsync, the data enable signal DE, and the master clock MCLK, to synchronize the operation timing of the data drive circuit 12 with the operation timing of the gating drive circuit 14. The scan timing control signals may include the gating start pulse GSP, the gating shift clock GSC, and the gating output enable signal GOE. The data timing control signals may include the source sampling clock SSC, the polarity control signal POL, and the source output enable signal SOE.

[0053] The host system 19 can transmit digital video data RGB and timing signals Vsync, Hsync, DE and MCLK to the timing controller 16, and can execute an application associated with touch coordinate information TDATA (XY) input from the touch driver 18.

[0054] During the display driving periods Td1 and Td2, the data driving circuit 12 can provide data voltages to data lines D1 to Dm under the control of the timing controller 16, and the gating driving circuit 14 can sequentially provide gating pulses synchronized with the data voltages to gating lines G1 to Gn under the control of the timing controller 16. Furthermore, the touch driving device 18 can cease operation during the display driving periods Td1 and Td2.

[0055] During touch driving periods Tt1 and Tt2, the touch driving device 18 can apply a touch driving signal LFD to the touch sensor of the touchscreen. Furthermore, during touch driving periods Tt1 and Tt2, one or more of the display driving circuits 12 and 14 can provide an alternating current (AC) signal with the same amplitude and phase as the touch driving signal LFD to signal lines D1 to Dm and G1 to Gn, in order to minimize parasitic capacitance between the touch sensor and the signal lines D1 to Dm and G1 to Gn connected to the pixels. In this case, display noise appearing in the touch sensing signal can be reduced.

[0056] Figure 4 This diagram illustrates the connection relationships between the display panel, the touch display driver integrated circuit (IC) (TDDI), and the common voltage compensation circuit.

[0057] Reference Figure 4 Each pixel 101 of the display panel PNL may include a thin film transistor (TFT) formed in the intersection between the data line DL and the gate line GL, a pixel electrode 1 charged with a data voltage, a common electrode 2 opposite to the pixel electrode 1, a liquid crystal cell Clc formed between the pixel electrode 1 and the common electrode 2, and a storage capacitor Cst connected to the pixel electrode 1 and the common electrode 2 to maintain the voltage of the liquid crystal cell Clc.

[0058] The common voltage compensation circuit CVC can be connected to the common electrode 1 of pixel 101 via a feedback line. The common voltage compensation circuit CVC receives the feedback common voltage Vcom_FB from the display panel PNL via the feedback line. Due to variations in the source output and the touch drive signal, ripple may appear in the feedback common voltage Vcom_FB. The common voltage ripple may increase proportionally to the swing width of the source output. The common voltage ripple can be an AC frequency component and can be used as EMI noise; therefore, it should be minimized. To cancel the common voltage ripple, the common voltage compensation circuit CVC can generate a common voltage compensation signal CVcom with a phase opposite to the ripple, and then output an AC common signal AC_VCOM, which combines the touch drive signal LFD and the common voltage compensation signal CVcom, to the TDDI. The TDDI can be referred to as the touch and display driver IC.

[0059] Electrostatic discharge (ESD) protection circuits used to protect circuits from ESD (see...) Figure 5 It can be electrically connected to the input / output (I / O) pads of TDDI. The ESD protection circuit can vary the clamping voltage based on whether ESD is detected, thus solving the traditional problem of the common voltage compensation signal CVcom being unconditionally clamped regardless of the ESD input.

[0060] When ESD is detected, the touch drive signal LFD can be clamped by the ESD protection circuit. When the touch drive signal LFD is clamped, touch sensing performance may be degraded; therefore, the TDDI may further include an LFD generation circuit. The touch drive signal LFD regenerated by the LFD generation circuit can be output to the touch sensor (e.g., the common electrode) during the touch drive period, and during the display drive period, a common voltage compensation signal CVcom, output by the ESD protection circuit, can be output to the common electrode.

[0061] Figure 5 This is a diagram illustrating the configuration of an ESD protection circuit that varies the clamping voltage based on whether ESD is detected. Figure 6 This is a diagram illustrating the detailed connection configuration of the clamping circuit, ESD detection circuit, and clamping voltage change circuit. Figure 7 This is a diagram illustrating examples of shifting positive / negative clamping voltages to a first voltage range based on non-ESD detection and shifting positive / negative clamping voltages to a second voltage range based on ESD detection.

[0062] Reference Figure 5 and Figure 6 The ESD protection circuit according to the embodiments of the present disclosure may include a clamping circuit 100, an ESD detection circuit 200, and a clamping voltage change circuit 300.

[0063] The clamping circuit 100 may include a first diode DD1 connected between the input pad IPD and a first voltage terminal TE1 that receives the positive clamping voltage PCV, and a second diode DD2 connected between the input pad IPD and a second voltage terminal TE2 that receives the negative clamping voltage NCV.

[0064] ESD detection circuit 200 can be connected between first diode DD1 (e.g., the cathode of first diode DD1) and first voltage terminal TE1 and between second diode DD2 (e.g., the cathode of second diode DD2) and input pad IPD, and can detect whether ESD occurs in the AC common signal AC_VCOM input through input pad IPD.

[0065] ESD detection circuit 200 may include a positive detection circuit PDT connected between the cathode of the first diode DD1 and the first voltage terminal TE1, and a negative detection circuit NDT connected between the cathode of the second diode DD2 and the input pad IPD. ESD detection circuit 200 may also include an analog-to-digital converter (ADC) and a counter CNT connected to the positive detection circuit PDT, and an analog-to-digital converter (ADC) and a counter CNT connected to the negative detection circuit NDT.

[0066] The positive detection circuit (PDT) generates an analog positive detection signal to determine whether the AC common signal (AC_VCOM) includes an ESD event. This analog positive detection signal can be an aperiodic detection signal caused by an ESD event or an overcurrent detection signal caused by an ESD event. The analog positive detection signal is converted into digital positive detection information by an analog-to-digital converter (ADC), and then input to a counter (CNT). The counter (CNT) outputs a positive count of the number of ESD events based on the digital positive detection information.

[0067] The negative detection circuit NDT generates an analog negative detection signal to determine whether the AC common signal AC_VCOM includes ESD. This analog negative detection signal can be an aperiodic detection signal caused by ESD or an overcurrent detection signal caused by ESD. The analog negative detection signal is converted into digital negative detection information by an analog-to-digital converter (ADC), and then input to a counter CNT. The counter CNT outputs a negative count of the number of ESD events based on the digital negative detection information.

[0068] The clamping voltage change circuit 300 may include a voltage control unit VCU of the controller CON and a power supply circuit PGR.

[0069] The voltage control unit (VCU) of the controller CON can receive positive and negative count information from the counter CNT. The voltage control unit VCU can determine whether ESD has been detected based on the positive and negative count information.

[0070] like Figure 7 As shown, when no ESD is detected, the voltage control unit VCU can control the power supply circuit PGR to change the difference or range between the positive clamping voltage PCV and the negative clamping voltage NCV to the first voltage range RNG1, thus allowing the clamping circuit 100 not to clamp the AC common signal AC_VCOM.

[0071] like Figure 7 As shown, when ESD is detected, the voltage control unit VCU can control the power supply circuit PGR to change the difference or range between the positive clamping voltage PCV and the negative clamping voltage NCV to a second voltage range RNG2 that is smaller or narrower than the first voltage range RNG1, thus allowing the clamping circuit 100 to clamp a portion of the AC common signal AC_VCOM.

[0072] The positive clamping voltage PCV1 defining the first voltage range RNG1 can be higher than the positive clamping voltage PCV2 defining the second voltage range RNG2. Furthermore, the negative clamping voltage NCV1 defining the first voltage range RNG1 can be lower than the negative clamping voltage NCV2 defining the second voltage range RNG2.

[0073] A switch SS can also be set between the input pad IPD and the output pad. Responding to the touch enable signal TEN, the switch SS can be turned on during the display drive period and off during the touch drive period. In this case, when the switch SS is set, the AC common signal AC_VCOM will be provided during the display drive period and may not be output to the display panel during the touch drive period.

[0074] During the display driving period, when ESD is detected, the common voltage compensation signal CVcom clamped to the second voltage range RNG2 can be output to the output pad, and when ESD is not detected, the unclamped common voltage compensation signal CVcom with the first voltage range RNG1 can be output to the output pad.

[0075] As described above, by varying the range of the clamping voltage based on whether ESD is detected, the common voltage compensation signal CVcom can be effectively prevented from being unconditionally clamped regardless of the ESD input.

[0076] Figure 8 This is a diagram illustrating the detailed configuration of an ESD detection circuit.

[0077] Each of the above-mentioned positive detection circuit PDT and negative detection circuit NDT can be as follows: Figure 8 The implementation is shown.

[0078] Each of the positive detection circuit PDT and the negative detection circuit NDT may include a first detector DET1 for generating an aperiodic detection signal and a second detector DET2 for generating an overcurrent detection signal.

[0079] like Figure 8 As shown, the first detector DET1 may include a first amplifier AMP1, which has a (-) input terminal for receiving the touch drive signal LFD, which receives the AC common signal AC_VCOM, during the touch drive period Tt; a (+) input terminal for receiving the reference voltage VREF; and an output terminal. The first amplifier AMP1 can output the result obtained by sensing the period of the touch drive signal LFD. For example, as Figure 8 As shown, the first detector DET1 can be connected to the AC common signal AC_VCOM through the switch SA which is turned on during the touch driving period Tt, so that the first detector DET1 can receive the touch driving signal LFD of the AC common signal AC_VCOM during the touch driving period Tt.

[0080] The first detector DET1 may include a counter-type comparator CCOM, which uses a reference clock to count the output of the first amplifier AMP1 to obtain a count value, and compares the count value with a pre-stored reference count value. When the count value differs from the reference count value, the counter-type comparator CCOM can detect the aperiodic ESD of the touch drive signal LFD.

[0081] like Figure 8 As shown, the second detector DET2 can detect overcurrent ESD included in the common voltage compensation signal CVcom of the AC common signal AC_VCOM during the display drive period Td. For example, as Figure 8 As shown, the second detector DET can be connected to the AC common signal AC_VCOM via another switch SB that is turned on during the display driving period Td, so that the second detector DET can receive the common voltage compensation signal CVcom of the AC common signal AC_VCOM during the display driving period Td.

[0082] The second detector DET2 may include: a second amplifier AMP2, which includes a (-) input terminal, a (+) input terminal, and an output terminal; a first resistor R1 connected between the (-) input terminal of the second amplifier AMP2 and the input of the AC common signal AC_VCOM; a second resistor R2 connected between the (-) input terminal and the output terminal of the second amplifier AMP2; a third resistor R3 connected between the (+) input terminal of the second amplifier AMP2 and a threshold voltage TH for defining overcurrent; and a fourth resistor R4 connected between the (+) input terminal of the second amplifier AMP2 and the ground voltage GND.

[0083] The second amplifier AMP2 can output the result obtained by sensing overcurrent. The first resistor R1 and the third resistor R3 can be several thousand ohms and can be equal to each other. The second resistor R2 and the fourth resistor R4 can be several megaohms and can be equal to each other.

[0084] Figure 9 This is a diagram illustrating whether a non-periodic ESD of the touch drive signal is detected during the touch drive period and the subsequent operation performed.

[0085] Reference Figure 9 According to the embodiments of the present disclosure, the ESD protection circuit can sense the period of the touch drive signal LFD of the AC common signal AC_VCOM during the touch drive period Tt.

[0086] When the touch drive signal LFD includes an abnormal ESD, the ESD protection circuit can detect the non-periodic signal and, based on the detection result, change the difference between the positive clamping voltage PCV and the negative clamping voltage NCV to a second voltage range RNG2. Therefore, the clamping circuit can clamp a portion of the AC common signal AC_VCOM. As a result, a common voltage compensation signal CVcom clamped by the clamping circuit can be output.

[0087] On the other hand, when the touch drive signal LFD does not include abnormal ESD, the ESD protection circuit may not detect the non-periodic signal, and can change the difference between the positive clamping voltage PCV and the negative clamping voltage NCV to a first voltage range RNG1 based on the non-detection result. Therefore, the AC common signal AC_VCOM can be bypassed in the clamping circuit without being clamped. As a result, a common voltage compensation signal CVcom that is not clamped by the clamping circuit can be output.

[0088] Figure 10 This is a diagram illustrating whether an overcurrent ESD that compensates for the common voltage is detected during the display driving period and the subsequent operations performed.

[0089] Reference Figure 10 According to the embodiments of the present disclosure, the ESD protection circuit can sense the overcurrent of the common voltage compensation signal CVcom of the AC common signal AC_VCOM during the display driving period Td.

[0090] When the touch drive signal LFD includes an abnormal ESD, the ESD protection circuit can detect the overcurrent and, based on the detection result, change the difference between the positive clamping voltage PCV and the negative clamping voltage NCV to a second voltage range RNG2. This allows the clamping circuit to clamp a portion of the AC common signal AC_VCOM. As a result, a common voltage compensation signal CVcom clamped by the clamping circuit can be output.

[0091] On the other hand, when the touch drive signal LFD does not include abnormal ESD, the ESD protection circuit may not detect overcurrent, and can change the difference between the positive clamping voltage PCV and the negative clamping voltage NCV to a first voltage range RNG1 based on the non-detection result. Therefore, the AC common signal AC_VCOM can be bypassed without being clamped in the clamping circuit. As a result, a common voltage compensation signal CVcom that is not clamped by the clamping circuit can be output.

[0092] Figure 11 This is an example of Figure 9 and Figure 10 A diagram illustrating examples of combinations of cases.

[0093] Reference Figure 11 According to the embodiments of the present disclosure, the ESD protection circuit can sense the period of the touch drive signal LFD of the AC common signal AC_VCOM during the touch drive period Tt, and can sense the overcurrent of the common voltage compensation signal CVcom of the AC common signal AC_VCOM during the display drive period Td.

[0094] When the touch drive signal LFD and / or the common voltage compensation signal CVcom includes abnormal ESD, the ESD protection circuit can detect the non-periodic signal and / or overcurrent, and can change the difference between the positive clamping voltage PCV and the negative clamping voltage NCV to a second voltage range RNG2 based on the detection result. Therefore, the clamping circuit can clamp a portion of the AC common signal AC_VCOM. As a result, the common voltage compensation signal CVcom clamped by the clamping circuit can be output.

[0095] On the other hand, when the touch drive signal LFD and the common voltage compensation signal CVcom do not include abnormal ESD, the ESD protection circuit may not detect aperiodic signals and overcurrents. Furthermore, based on the non-detection result, the difference between the positive clamping voltage PCV and the negative clamping voltage NCV can be varied to a first voltage range RNG1. Therefore, the AC common signal AC_VCOM can be bypassed without being clamped in the clamping circuit. As a result, a common voltage compensation signal CVcom that is not clamped by the clamping circuit can be output.

[0096] This disclosure can achieve the following effects.

[0097] The touch-sensing display device according to embodiments of this disclosure can vary the clamping voltage differently based on whether ESD is detected, and can prevent the common voltage compensation signal from being unconditionally clamped regardless of the ESD input. As a result, the compensation effect for common voltage ripple can be maximized, thereby enhancing display quality.

[0098] The effects of this disclosure are not limited to the examples above, and various other effects may be included in the specification.

[0099] Although this disclosure has been specifically shown and described with reference to its exemplary embodiments, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the technical concept and scope of this disclosure as defined by the appended claims.

Claims

1. A touch-sensing display device, the touch-sensing display device comprising: A clamping circuit, the clamping circuit including a first diode connected between an input pad and a first voltage terminal receiving a positive clamping voltage, and a second diode connected between the input pad and a second voltage terminal receiving a negative clamping voltage; An electrostatic discharge (ESD) detection circuit is connected between the first diode and the first voltage terminal and between the second diode and the input pad to detect whether the AC common signal input through the input pad includes ESD; and A clamping voltage variation circuit is configured to vary the range between the positive clamping voltage and the negative clamping voltage differently based on whether the ESD is detected, such that a first voltage range between the positive clamping voltage and the negative clamping voltage when the ESD is not detected is greater than a second voltage range between the positive clamping voltage and the negative clamping voltage when the ESD is detected.

2. The touch sensing display device according to claim 1, wherein, The first voltage range is configured such that the AC common signal is not clamped in the clamping circuit, and the second voltage range is configured such that a portion of the AC common signal is clamped in the clamping circuit.

3. The touch sensing display device according to claim 1, wherein, The positive clamping voltage for the first voltage range is defined to be higher than the positive clamping voltage for the second voltage range, and The negative clamping voltage of the first voltage range is defined as lower than the negative clamping voltage of the second voltage range.

4. The touch-sensing display device according to claim 1, further comprising a common voltage compensation circuit, the common voltage compensation circuit being configured to receive a feedback common voltage from the display panel, generate a common voltage compensation signal for compensating for the ripple of the feedback common voltage, and output the AC common signal combining the touch drive signal and the common voltage compensation signal. in, A frame includes at least one touch-driven period and at least one display-driven period. The touch drive signal of the AC common signal corresponds to the touch drive period, and The common voltage compensation signal of the AC common signal corresponds to the display driving period.

5. The touch sensing display device according to claim 4, wherein, The touch and display driver integrated circuit is disposed between the common voltage compensation circuit and the display panel, and The clamping circuit and the ESD detection circuit are included in the touch and display driver integrated circuit.

6. The touch sensing display device according to claim 4, wherein, The ESD detection circuit includes: A first detector, configured to detect aperiodic ESD of the touch driving signal during the touch driving period; and A second detector is configured to detect overcurrent ESD of the common voltage compensation signal during the display driving period.

7. The touch sensing display device according to claim 6, wherein, The first detector includes: A first amplifier, comprising a (-) input terminal for receiving the touch drive signal of the AC common signal during the touch drive period, a (+) input terminal for receiving a reference voltage, and an output terminal; and A counter-type comparator is configured to detect aperiodic ESD of the touch drive signal when the count value output by the first amplifier differs from a pre-stored reference count value.

8. The touch sensing display device according to claim 6, wherein, The second detector includes: The second amplifier includes a (-) input terminal, a (+) input terminal, and an output terminal; A first resistor is connected between the (-) input terminal of the second amplifier and the input of the AC common signal; A second resistor is connected between the (-) input terminal and the output terminal of the second amplifier; A third resistor is connected between the (+) input terminal of the second amplifier and a threshold voltage for defining overcurrent; and A fourth resistor is connected between the (+) input terminal of the second amplifier and the ground voltage.

9. The touch-sensing display device of claim 4, further comprising a switch between the input pad and the output pad and configured to be on during the display driving period and off during the touch driving period.

10. The touch-sensing display device according to claim 1, wherein, The clamping voltage change circuit is included in the timing controller of the touch sensing display device.

11. A voltage control method for a touch-sensing display device, the touch-sensing display device including a clamping circuit, the clamping circuit including a first diode connected between an input pad and a first voltage terminal receiving a positive clamping voltage and a second diode connected between the input pad and a second voltage terminal receiving a negative clamping voltage, the voltage control method comprising the following steps: In the electrostatic discharge (ESD) detection circuit connected between the first diode and the first voltage terminal and between the second diode and the input pad, it detects whether the AC common signal input through the input pad includes ESD; and The range between the positive clamping voltage and the negative clamping voltage is varied differently depending on whether the ESD is detected, such that a first voltage range between the positive clamping voltage and the negative clamping voltage when the ESD is not detected is greater than a second voltage range between the positive clamping voltage and the negative clamping voltage when the ESD is detected.

12. The voltage control method according to claim 11, wherein, The first voltage range is configured such that the AC common signal is not clamped in the clamping circuit, and the second voltage range is configured such that a portion of the AC common signal is clamped in the clamping circuit.

13. The voltage control method according to claim 11, wherein, The positive clamping voltage for the first voltage range is defined to be higher than the positive clamping voltage for the second voltage range, and The negative clamping voltage of the first voltage range is defined as lower than the negative clamping voltage of the second voltage range.

14. The voltage control method according to claim 11, further comprising the following steps: The system receives a feedback common voltage from the display panel, generates a common voltage compensation signal to compensate for the ripple of the feedback common voltage, and outputs the AC common signal, which combines the touch drive signal and the common voltage compensation signal. A frame includes at least one touch-driven period and at least one display-driven period. The touch drive signal of the AC common signal corresponds to the touch drive period, and The common voltage compensation signal of the AC common signal corresponds to the display driving period.

Images