KR20220066767A - Display device and driving method for advancing electro magnetic interface - Google Patents

Abstract

Embodiments of the present invention relate to a display device and driving method capable of improving an electromagnetic interference. More specifically, by controlling an inclination of the data voltage by reflecting a fluctuation of a common voltage, the present invention relates to the display device and driving method capable of improving the electromagnetic interference. The display device comprises: a display panel; a common voltage detection circuit; an inclination level control circuit; and an output selection circuit.

Description

DISPLAY DEVICE AND DRIVING METHOD FOR ADVANCING ELECTRO MAGNETIC INTERFACE

Embodiments of the present invention relate to a display device capable of improving electromagnetic interference and a driving method.

As the information society develops, the demand for a display device for displaying an image is increasing in various forms. As a display device, various display devices such as a liquid crystal display (LCD), an organic light emitting display, or a quantum dot light emitting display (QLED) are used.

In order to provide more various functions, such a display device provides a function of recognizing a user's finger touch or pen touch on the display panel and performing input processing based on the recognized touch.

For example, a display device capable of recognizing a touch may include a plurality of touch electrodes disposed or embedded in a display panel, and by driving these touch electrodes, the presence or absence of a user's touch on the display panel, touch coordinates, and the like may be detected.

As such a touch recognition-capable display device provides both an image display function and a touch sensing function through a display panel, there is a problem that the touch sensing may affect the display driving or the performance of the touch sensing may be deteriorated due to the display driving. do.

Embodiments of the present invention may provide a display device and a driving method capable of improving electromagnetic interference generated during a display or touch sensing process.

In addition, embodiments of the present invention may provide a display apparatus and a driving method capable of improving electromagnetic interference by controlling a slope of a data voltage by reflecting a change in a common voltage.

According to an embodiment of the present invention, there is provided a display panel comprising: a display panel in which a plurality of subpixels are disposed, a common voltage line for applying a common voltage to the common electrode and a feedback line through which a feedback common voltage fed back through the common electrode is transmitted; A common voltage detection circuit detecting a common voltage variation value through a feedback line, a slope level control circuit determining a slope level of a data voltage corresponding to the common voltage variation value, and data supplied to the display panel to correspond to the determined slope level A display device including an output selection circuit for changing a slope level of a voltage may be provided.

According to an embodiment of the present invention, it is possible to provide a display device in which the feedback line is located adjacent to the common voltage line on the side of the display panel or in a loop shape along the non-display area surrounding the display area of the display panel. have.

According to an embodiment of the present invention, the common voltage detection circuit includes an operational amplifier that compares a feedback common voltage and a reference common voltage, and an analog-to-digital converter that converts a common voltage variation output through the operational amplifier into a digital value. A display device may be provided.

According to an embodiment of the present invention, the operational amplifier receives a feedback common voltage to an inverting input terminal, receives a reference common voltage to a non-inverting input terminal, and a display device including a capacitor connected between the inverting input terminal and the output terminal can provide

According to an embodiment of the present invention, the analog-to-digital converter includes a plurality of resistors connected in series to branch a reference voltage, a plurality of comparators for comparing a common voltage variation value and a branched reference voltage, and output values of the comparators to a digital signal It is possible to provide a display device including an encoder for converting to .

According to an embodiment of the present invention, the common voltage detection circuit may provide a display device that detects a common voltage variation value in a rising section or a falling section of a data voltage.

According to an embodiment of the present invention, the common voltage detection circuit may provide a display device located in the data driving circuit that supplies the data voltage to the display panel.

According to an embodiment of the present invention, the slope level control circuit extracts a corresponding slope level from a lookup table according to the digital common voltage fluctuation value output from the common voltage detection circuit, and controls the data voltage according to the extracted slope level It is possible to provide a display device that transmits a tilt control signal for

According to an embodiment of the present invention, the slope level control circuit may provide a display device located in a timing controller that controls a data driving circuit for supplying a data voltage to the display panel.

According to an embodiment of the present invention, the output selection circuit is located in a data driving circuit that supplies a data voltage to the display panel, a plurality of switches connected in parallel to an output buffer of the data driving circuit, and a plurality of switches connected in series to each of the plurality of switches A display device including a plurality of damping resistors may be provided.

According to an embodiment of the present invention, it is possible to provide a display device in which the slope level of the data voltage is changed during the rising period of the data voltage.

According to an embodiment of the present invention, it is possible to provide a display device that greatly increases the slope level in the rising period of the data voltage as the common voltage fluctuation value increases.

According to another embodiment of the present invention, a display panel including a common voltage line for applying a common voltage to a common electrode and a feedback line through which a feedback common voltage fed back through the common electrode is formed is formed, and a data voltage is supplied to the display panel. A method of driving a display device including a data driving circuit, the method comprising: detecting a change in a common voltage transmitted through a feedback line; and determining a slope level of a data voltage applied to a display panel according to the common voltage change value; and supplying a data voltage to the display panel according to the determined inclination level.

According to another embodiment of the present invention, the detecting of the variation of the common voltage includes comparing the feedback common voltage and the reference common voltage, and converting the common voltage variation generated according to the comparison result into a digital value. A method of driving a display device can be provided.

According to another embodiment of the present invention, the detecting of the variation of the common voltage may provide a method of driving a display device for detecting a common voltage variation value in a rising section or a falling section of the data voltage.

According to another embodiment of the present invention, the determining of the slope level includes: extracting a corresponding slope level from a lookup table according to a common voltage variation value; and slope control for controlling the data voltage according to the extracted slope level It is possible to provide a method of driving a display device including transmitting a signal.

According to another embodiment of the present invention, it is possible to provide a method of driving a display device in which the slope level of the data voltage is changed during the rising period of the data voltage.

According to another embodiment of the present invention, it is possible to provide a method of driving a display device in which the slope level in the rising period of the data voltage is greatly increased as the common voltage variation value increases.

According to embodiments of the present invention, it is possible to provide a display device and a driving method capable of improving electromagnetic interference generated during a display or touch sensing process.

In addition, according to embodiments of the present invention, it is possible to provide a display device and a driving method capable of improving electromagnetic interference by controlling a slope of a data voltage by reflecting a change in a common voltage.

1 is a view showing a schematic configuration of a display device according to embodiments of the present invention.
2 is a diagram illustrating a structure of a touch electrode disposed on a display panel and a touch driving circuit for driving the touch electrode and detecting a touch in a display device according to embodiments of the present invention.
3 is a diagram illustrating an example of display driving and touch sensing timing in a display device according to embodiments of the present invention, and is a diagram illustrating a case in which display driving and touch sensing are performed in time-divided periods.
4 is a diagram illustrating a case in which display driving and touch sensing are simultaneously performed in a display device according to embodiments of the present invention.
5 is a diagram illustrating an example of electromagnetic interference that may occur in driving a display in a display device according to embodiments of the present invention.
6 is a diagram illustrating an effect of a data voltage and electromagnetic interference due to inversion driving in a display device according to embodiments of the present invention.
7 is a flowchart schematically illustrating a method of driving a display apparatus according to embodiments of the present invention.
8 is a diagram illustrating an example of a structure for detecting a change in a common voltage in a display device according to embodiments of the present invention.
9 is a circuit diagram illustrating an example of a common voltage detection circuit for detecting a change in a common voltage in a display device according to embodiments of the present invention.
10 is a diagram illustrating electromagnetic interference occurring in a rising or falling section of a scan signal in addition to a data voltage in a display device according to embodiments of the present invention.
11 is a block diagram illustrating a case in which a lookup table for storing a slope level of a data voltage and an interface circuit for transmitting slope control information are provided in a timing controller in a display device according to embodiments of the present disclosure;
12 is a diagram illustrating an example of a lookup table for storing a plurality of slope levels corresponding to a digital common voltage variation value in a display device according to embodiments of the present invention.
13 is a circuit diagram illustrating an example of a slope control circuit included in a data driving circuit in a display device according to embodiments of the present invention.
14 is a signal waveform diagram illustrating an example of changing a slope level of a data voltage according to a variation value of a common voltage in a display device according to embodiments of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. In adding reference numerals to components of each drawing, the same components may have the same reference numerals as much as possible even though they are indicated in different drawings. In addition, in describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description may be omitted. When "includes", "having", "consisting of", etc. mentioned in this specification are used, other parts may be added unless "only" is used. When a component is expressed in the singular, it may include a case in which the plural is included unless otherwise explicitly stated.

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

In the description of the positional relationship of the components, when it is described that two or more components are "connected", "coupled" or "connected", two or more components are directly "connected", "coupled" or "connected" ", but it will be understood that two or more components and other components may be further "interposed" and "connected," "coupled," or "connected." Here, other components may be included in one or more of two or more components that are “connected”, “coupled” or “connected” to each other.

In the description of the temporal flow relationship related to the components, the operation method or the production method, for example, the temporal precedence relationship such as "after", "after", "after", "before", etc. Alternatively, when a flow precedence relationship is described, it may include a case where it is not continuous unless "immediately" or "directly" is used.

On the other hand, when numerical values or corresponding information (eg, level, etc.) for a component are mentioned, even if there is no separate explicit description, the numerical value or the corresponding information is based on various factors (eg, process factors, internal or external shock, Noise, etc.) may be interpreted as including an error range that may occur.

1 is a view showing a schematic configuration of a display device according to embodiments of the present invention.

Referring to FIG. 1 , a display apparatus 100 according to embodiments of the present invention includes a display panel 110 , a gate driving circuit 120 , a data driving circuit 130 , a timing controller 140 , and a display panel. A touch driving circuit 150 for sensing a touch to 110 may be included.

In the display panel 110 , a plurality of gate lines GL and a plurality of data lines DL are disposed, and a plurality of subpixels SP are formed in a region where the gate line GL and the data line DL intersect. are placed

In addition, a plurality of touch electrodes may be disposed or embedded in the display panel 110 , and a plurality of sensing lines SL that electrically connect the touch electrodes and the touch driving circuit 150 to each other may be disposed.

First, a configuration for driving a display in the display apparatus 100 will be described. The gate driving circuit 120 controls the driving timing of the sub-pixels SP disposed on the display panel 110 . Then, the data driving circuit 130 supplies the data voltage corresponding to the image data to the sub-pixel SP so that the sub-pixel SP displays the brightness corresponding to the gray level of the image data, thereby displaying an image.

Specifically, the gate driving circuit 120 is controlled by the timing controller 140 and sequentially outputs a scan signal to the plurality of gate lines GL disposed on the display panel 110 to the plurality of sub-pixels SP. ) to control the driving timing.

The gate driving circuit 120 may include one or more gate driving integrated circuits (GDIC), and may be located on only one side or both sides of the display panel 110 depending on the driving method. have. Alternatively, the gate driving circuit 120 may be built in a bezel area of the display panel 110 to be implemented in the form of a gate in panel (GIP).

The data driving circuit 130 receives digital image data DATA from the timing controller 140 and converts the image data into analog data voltage. In addition, the data voltage is outputted to each data line DL according to the timing at which the scan signal is applied through the gate line GL, so that each subpixel SP expresses brightness according to the data voltage.

The data driving circuit 130 may include one or more source driving integrated circuits (SDICs).

The timing controller 140 supplies various control signals to the gate driving circuit 120 and the data driving circuit 130 , and controls operations of the gate driving circuit 120 and the data driving circuit 130 .

The timing controller 140 causes the gate driving circuit 120 to output a scan signal according to the timing implemented in each frame, and converts externally received image data to match the data signal format used by the data driving circuit 130 . Thus, the converted image data DATA is output to the data driving circuit 130 .

The timing controller 140 receives various timing signals including a vertical synchronization signal, a horizontal synchronization signal, an input data enable signal, and a clock signal from the outside (eg, a host system) together with the image data DATA.

The timing controller 140 may generate various control signals DCS and GCS by using various timing signals received from the outside, and may output them to the gate driving circuit 120 and the data driving circuit 130 .

For example, in order to control the gate driving circuit 120 , the timing controller 140 transmits a gate start pulse, a gate shift clock, a gate output enable signal, and the like. and various gate control signals GCS.

Here, the gate start pulse controls the operation start timing of one or more gate driving integrated circuits constituting the gate driving circuit 120 . The gate shift clock is a clock signal commonly input to one or more gate driving integrated circuits, and controls shift timing of the scan signal. The gate output enable signal specifies timing information of one or more gate drive integrated circuits.

Also, in order to control the data driving circuit 130 , the timing controller 140 includes a source start pulse, a source sampling clock, a source output enable signal, and the like. and various data control signals DCS.

Here, the source start pulse controls the data sampling start timing of one or more source driving integrated circuits constituting the data driving circuit 130 . The source sampling clock is a clock signal that controls sampling timing of data in each of the source driving integrated circuits. The source output enable signal controls the output timing of the data driving circuit 130 .

The display device 100 supplies various voltages or currents to the display panel 110 , the gate driving circuit 120 , the data driving circuit 130 , and the touch driving circuit 150 , or controls various voltages or currents to be supplied. It may further include a power management integrated circuit that

Each subpixel SP is defined by the intersection of the gate line GL and the data line DL, and a liquid crystal or a light emitting device may be disposed according to the type of the display device 100 .

For example, when the display device 100 is a liquid crystal display device, it includes a light source device such as a backlight unit irradiating light to the display panel 110 , and liquid crystal is disposed in the subpixels SP of the display panel 110 . do. In addition, by adjusting the arrangement of liquid crystals by an electric field formed when a data voltage is applied to each subpixel SP, an image can be displayed with brightness according to the data voltage.

In the case of a liquid crystal display device, the display panel 110 includes a liquid crystal layer formed between two substrates, and includes a twisted nematic (TN) mode, a vertical alignment (VA) mode, an in plane switching (IPS) mode, and a fringe field (FFS) mode. Switching) mode, etc., may be operated in any known mode. On the other hand, in the case of an organic light emitting display device, the display panel 110 may be implemented using a top emission method, a bottom emission method, or a dual emission method.

Meanwhile, the display apparatus 100 according to embodiments of the present invention may detect a user's touch on the display panel 110 using a touch electrode and a touch driving circuit 150 included in the display panel 110 . have.

2 is a diagram illustrating a structure of a touch electrode disposed on a display panel and a touch driving circuit for driving the touch electrode and detecting a touch in a display device according to embodiments of the present invention.

Referring to FIG. 2 , in the display device 100 according to embodiments of the present invention, a plurality of touch electrodes TE are provided on the display panel 110 , and the touch electrodes TE are connected to the touch driving circuit 150 . A plurality of sensing lines SL may be disposed.

The touch electrode TE may be disposed on or embedded in the display panel 110 . In addition, the touch electrode TE may be an electrode used for driving a display or an electrode separately disposed for touch sensing. In addition, the touch electrode TE may have a transparent conductive electrode shape or an opaque mesh shape.

For example, when the display device 100 is a liquid crystal display device, the touch electrode TE may be a common electrode embedded in the display panel 110 to which a common voltage is applied when the display is driven.

That is, the common electrode is disposed in a divided structure on the display panel 110 and may be used as the touch electrode TE for touch sensing. Accordingly, each of the touch electrodes TE may be disposed to overlap the plurality of sub-pixels SP.

The touch electrode TE is connected to the touch driving circuit 150 through the sensing line SL disposed on the display panel 110 .

The touch driving circuit 150 may include a touch sensing circuit connected to the touch electrode TE through the sensing line SL, and a touch controller that controls the touch sensing circuit and detects a touch. In addition, it may include a touch power circuit for supplying a touch driving signal to the touch sensing circuit under the control of the touch controller.

At least a portion of the touch driving circuit 150 may be implemented integrally with the data driving circuit 130 or the timing controller 140 . In this case, at least a part of the operation of the touch driving circuit 150 may be processed by the data driving circuit 130 or the timing controller 140 .

The touch sensing circuit outputs a touch driving signal to the plurality of touch electrodes TE and receives a touch sensing signal from the plurality of touch electrodes TE. The touch sensing circuit may perform touch sensing in a touch sensing period separated from the display driving period, or may perform touch sensing simultaneously with the display driving period.

Such a touch sensing circuit may be connected to the touch electrode TE in a one-to-one manner to receive a touch sensing signal. That is, the touch sensing circuit outputs a touch driving signal to the touch electrode TE through the sensing line SL, receives the touch sensing signal, and senses a change in self capacitance generated by the touch. .

Alternatively, the touch electrode TE may be divided into a touch driving electrode and a touch sensing electrode, and the touch sensing circuit may be respectively connected to the touch driving electrode and the touch sensing electrode. In this case, the touch sensing circuit outputs a touch driving signal to the touch driving electrode and receives the touch sensing signal from the touch sensing electrode, and a change in mutual capacitance between the touch driving electrode and the touch sensing electrode generated by the touch can be sensed.

The touch sensing circuit converts the received touch sensing signal into digital form of touch sensing data and transmits the converted touch sensing data to the touch controller.

The touch controller may control driving of the touch sensing circuit, receive touch sensing data from the touch sensing circuit, and detect a user's touch on the display panel 110 based on the received touch sensing data.

That is, the touch controller may detect a change in self-capacitance or a change in mutual capacitance from the touch sensing data, and detect the presence or absence of a touch and touch coordinates based on the detected change in capacitance.

As described above, the touch sensing by the touch driving circuit 150 may be performed in a time-division period from driving the display, or may be performed simultaneously with driving the display.

3 is a diagram illustrating an example of display driving and touch sensing timing in a display device according to embodiments of the present invention, and is a diagram illustrating a case in which display driving and touch sensing are performed in time-divided periods.

Referring to FIG. 3 , in the display apparatus 100 according to embodiments of the present invention, a touch electrode TE included in the display panel 110 is driven in a period between display driving periods (eg, a blank period) to make a touch. sensing can be performed.

For example, the display apparatus 100 may perform touch sensing in a vertical blank period that exists for each image frame. Alternatively, touch sensing may be performed in some horizontal blank periods among a plurality of horizontal blank periods existing in one image frame.

When the common electrode included in the display panel 110 is used as the touch electrode TE, a common voltage is applied to the touch electrode TE during the display driving period and the touch driving signal TDS is applied to the touch electrode TE during the touch sensing period. ) can be approved.

The touch driving signal TDS may be a signal in the form of a pulse in which the magnitude of the voltage changes according to time.

Here, since display driving is not performed during the touch sensing period, no voltage is applied to electrodes, signal lines, etc. for driving the display, or the display may be in a constant voltage state (eg, the gate high voltage VGH). Accordingly, a capacitance may be formed between the touch electrode TE to which the touch driving signal TDS is applied, the gate line GL, and the data line DL, and the detection performance of the touch sensing signal may be deteriorated due to this capacitance. can

In order to prevent capacitance formed between the touch electrode TE, the gate line GL, and the data line DL, a voltage equal to the touch driving signal TDS applied to the touch electrode TE during the touch sensing period and A signal having a phase may be supplied to the gate line GL, the data line DL, or the like.

That is, as shown in FIG. 3 , the data voltage Vdata having the same voltage and phase as the touch driving signal TDS may be supplied to the data line DL. In addition, since the gate low voltage VGL is applied to the gate line GL during the touch sensing period, a signal having the same voltage and phase as the touch driving signal TDS may be output as the gate low voltage VGL. .

As described above, by supplying a signal having the same voltage and phase as the touch driving signal TDS to the gate line GL and the data line DL during the touch sensing period, capacitance between the touch electrode TE and the signal line is increased. By preventing it from being formed, it is possible to improve the detection performance of the touch sensing signal.

Meanwhile, the display apparatus 100 according to embodiments of the present invention may simultaneously perform display driving and touch sensing.

4 is a diagram illustrating a case in which display driving and touch sensing are simultaneously performed in a display device according to embodiments of the present invention.

Referring to FIG. 4 , in the display apparatus 100 according to embodiments of the present invention, touch sensing may be performed simultaneously with the display driving period.

Here, the touch sensing period may be the same as the display driving period or may be any period between the display driving periods. That is, the touch sensing may be independently performed regardless of driving the display, and accordingly, the touch sensing may be performed simultaneously with driving the display.

When touch sensing is performed simultaneously with driving the display, the touch driving signal TDS is applied to the touch electrode TE. In addition, the data voltage Vdata is supplied to the data line DL for driving the display, and a gate high voltage VGH, a gate low voltage VGL, etc. used to output a scan signal applied to the gate line GL. This can be output.

In this case, when the common electrode included in the display panel 110 is used as the touch electrode TE, since the touch driving signal TDS is applied to the touch electrode TE, the pixel to which the common electrode and the data voltage Vdata are applied. A voltage difference corresponding to the image data may not be formed between the electrodes.

That is, since the voltage of the touch driving signal TDS changes with time, a voltage difference corresponding to the image data is not formed between the common electrode to which the touch driving signal TDS is applied and the pixel electrode, so that the subpixel SP becomes an image. The brightness corresponding to the data may not be displayed.

Accordingly, by supplying the data voltage Vdata modulated based on the touch driving signal TDS to the data line DL, a voltage corresponding to image data is provided between the common electrode and the pixel electrode to which the touch driving signal TDS is applied. Allow the car to form.

The modulation of the data voltage Vdata may be performed, for example, by modulating the gamma voltage used to generate the data voltage Vdata in the data driving circuit 130 . Alternatively, the modulated data voltage Vdata may be supplied to the data line DL by modulating the ground voltage disposed on the display panel 110 .

In addition, by modulating a gate high voltage VGH and a gate low voltage VGL used to generate a scan signal supplied to the gate line GL based on the touch driving signal TDS, the The modulated scan signal may be applied so that the gate line GL is normally driven.

As described above, the gate high voltage VGH and the gate low voltage VGL used to generate the data voltage Vdata applied to the data line DL and the scan signal applied to the gate line GL are applied to the touch driving signal. By performing modulation based on (TDS), it is possible to simultaneously perform display driving and touch sensing.

Meanwhile, in the display apparatus 100 according to embodiments of the present invention, display driving may be performed in an inversion method in which the data voltage Vdata is inverted based on the common voltage Vcom for image quality. Such inversion may be performed in various forms, such as a frame unit, a column unit, or a subpixel (SP) unit.

When the display is driven in this inversion method, the voltage fluctuation of the data line DL is large as the data voltage Vdata is inverted, so that the display driving or touch sensing using the common electrode as the touch electrode TE is affected. can give

5 is a diagram illustrating an example of electromagnetic interference that may occur in driving a display in a display device according to embodiments of the present invention.

Here, as an example of performing inversion in units of columns, a structure in which data lines DL are alternately connected to subpixels SP disposed on both sides is illustrated as an example.

Referring to FIG. 5 , in the display device 100 according to embodiments of the present invention, since inversion is performed in units of columns, the subpixels SP disposed in the first column and the third column have the same polarity based on a common voltage. A data voltage Vdata having a In addition, a data voltage Vdata having a polarity different from that of the first and third columns may be supplied to the subpixels SP disposed in the second and fourth columns.

Here, since the data line DL is alternately connected to the subpixels SP disposed on both sides, the data voltage Vdata supplied to the data line DL has a polarity for each subpixel SP based on the common voltage. can be reversed.

At this time, since the capacitance is formed between the data line DL and the touch electrode TE, the touch driving applied to the touch electrode TE due to the inversion of the data voltage Vdata applied to the data line DL. Electromagnetic interference (EMI) may be generated in the signal (TDS) or the common voltage.

As a result, noise may be generated in the touch sensing signal TSS sensed through the touch electrode TE to deteriorate the performance of touch sensing, or noise may be introduced into an image displayed through the display panel 110 .

6 is a diagram illustrating an effect of a data voltage and electromagnetic interference due to inversion driving in a display device according to embodiments of the present invention.

Referring to FIG. 6 , in the display device 100 according to embodiments of the present invention, the data voltage Vdata may be applied in a form in which the polarity is inverted in units of frames, columns, or subpixels SP. have.

For example, a first data voltage Vdata1 is applied to the first frame or first column, and a second data voltage Vdata2 having a polarity opposite to that of the first data voltage Vdata1 is applied to the second frame or second column. This may be authorized.

In this case, the rising section of the first data voltage Vdata1 and the falling section of the second data voltage Vdata2 may overlap each other. Electromagnetic interference (EMI) increases in the interval.

This is a phenomenon that occurs because the rising slope Slope_R corresponding to the rising section of the first data voltage Vdata1 and the falling slope Slope_F corresponding to the falling section of the second data voltage Vdata2 are different.

As such, the rising slope Slope_R corresponding to the rising section of the data voltages Vdata1 and Vdata2 and the falling slope Slope_F corresponding to the falling section of the data voltages Vdata1 and Vdata2 are transmitted to the data driving circuit 130 for outputting the data voltages Vdata1 and Vdata2. It may vary depending on the output characteristics of the positioned source driving integrated circuit SDIC or the timing margin of the display panel 110 .

That is, it is difficult for the rising slope Slope_R and the falling slope Slope_F of the data voltages Vdata1 and Vdata2 to become symmetrical due to characteristics of circuit elements constituting the data driving circuit 130 .

Alternatively, in order to reduce heat generation of the sub-pixels SP to which the data voltages Vdata1 and Vdata2 are supplied during the display driving period, the rising slope Slope_R of the data voltages Vdata1 and Vdata2 is intentionally decreased, and the data voltage Vdata1 , Vdata2) may increase the falling slope Slope_F of the data voltages Vdata1 and Vdata2 so that adjacent sections to which are applied do not overlap.

As described above, when the rising slope Slope_R and the falling slope Slope_F of the data voltages Vdata1 and Vdata2 are formed to be different, noise due to electromagnetic interference increases in the rising section and the falling section of the data voltages Vdata1 and Vdata2. This causes a ripple in the common voltage applied to the display panel 110 .

In order to solve this problem, the present invention increases the slope of the data voltage Vdata output from the data driving circuit 130 to reduce the ripple of the common voltage when the common voltage of the display panel 110 varies. make it controllable.

7 is a flowchart schematically illustrating a method of driving a display apparatus according to embodiments of the present invention.

Referring to FIG. 7 , in the method of driving the display apparatus 100 according to embodiments of the present invention, the step of detecting a change in the common voltage ( S100 ), the slope level of the data voltage Vdata according to the change value of the common voltage It may include determining (S200) and supplying the data voltage (Vdata) according to the determined slope level (S300).

The step of detecting the variation of the common voltage ( S100 ) is a process of detecting a variation changed from the reference common voltage by sensing the variation of the common voltage applied to the display panel 110 .

To this end, the display device 100 of the present invention may include a common voltage line for applying a common voltage to the display panel 110 and a feedback line for detecting the common voltage.

8 is a diagram illustrating an example of a structure for detecting a change in a common voltage in a display device according to embodiments of the present invention.

Referring to FIG. 8 , the display device 100 according to embodiments of the present invention is transmitted through a common voltage line CL supplying a common voltage Vcom to the display panel 110 and the display panel 110 . It includes a feedback line FL that transmits the feedback common voltage Vcom_FB and a common voltage detection circuit 160 that detects a change in the common voltage based on the feedback common voltage Vcom_FB.

The common voltage detection circuit 160 continuously receives the feedback common voltage Vcom_FB transmitted from the display panel 110 through the feedback line FL, and corresponds to a variation value of the common voltage according to a deviation from the reference common voltage. signal can be output.

In this case, the common voltage Vcom is supplied to the left common voltage line CL_L and the right common voltage line CL_R through the common voltage line CL extended from the common voltage detection circuit 160 , and the left common voltage line A common voltage Vcom may be applied to the inside of the display panel 110 from (CL_L) and the right common voltage line CL_R, respectively.

The common voltage Vcom supplied to the display area of the display panel 110 in the horizontal direction from the left common voltage line CL_L and the right common voltage line CL_R is a horizontal common voltage line CL_H inside the display panel 110 . can be transmitted through

The left feedback line FL_L is connected to the end of the left common voltage line CL_L, and the right feedback line FL_R is connected to the end of the right common voltage line CL_R. The common voltage Vcom is transferred to the common voltage detection circuit 160 .

In this case, the feedback line FL that transmits the feedback common voltage Vcom_FB may be located on the side of the display panel 110 , and loops along the non-display area in a form surrounding the display area of the display panel 110 . It can also be placed in the form The common voltage feedback line FL may be formed in various shapes in the display panel 110 .

9 is a circuit diagram illustrating an example of a common voltage detection circuit for detecting a change in a common voltage in a display device according to embodiments of the present invention.

Referring to FIG. 9 , in the display device 100 according to embodiments of the present invention, the common voltage detection circuit 160 includes an operational amplifier Amp that compares the feedback common voltage Vcom_FB and the reference common voltage Vcom_ref, and It may include an analog-to-digital converter (ADC) 162 for converting the variation value of the common voltage into a digital value.

The operational amplifier (Amp) receives the feedback common voltage (Vcom_FB) transmitted through the display panel 110 to the inverting input terminal (-), and receives the reference common voltage (Vcom_ref) to the non-inverting input terminal (+), A capacitor C is connected between the inverting input terminal (-) and the output terminal.

Since the capacitor C is connected between the inverting input terminal (-) and the output terminal of the operational amplifier Amp, the operational amplifier Amp corresponds to the difference between the feedback common voltage Vcom_FB and the reference common voltage Vcom_ref. It is possible to accumulate and output the variation values of the common voltage.

The common voltage variation value Amp_Out accumulated through the operational amplifier Amp may be converted into a digital common voltage variation value ADC_OUT in the analog-to-digital converter 162 .

The analog-to-digital converter 162 compares a reference voltage Vref branched by a plurality of resistors R connected in series with a digital common voltage variation value ADC_OUT, and an output value of the comparator COMP. It may be made of an encoder (Encoder) that converts to a digital signal.

The common voltage detection circuit 160 may be located in the data driving circuit 130 or may be located in a source printed circuit board (SPCB) on which the data driving circuit 130 is mounted. Alternatively, the common voltage detection circuit 160 may be located in the timing controller 140 or may be located in a control printed circuit board (CPCB) on which the timing controller 140 is mounted.

As described above, by determining the slope of the data voltage Vdata generated by the data driving circuit 130 according to the digital common voltage variation value ADC_OUT generated by the common voltage detection circuit 160 , the data voltage Vdata is It is possible to reduce electromagnetic interference occurring in the rising section and the falling section.

The display driving method of the present invention can reduce electromagnetic interference by varying the slope level of the data voltage Vcom according to the variation value of the common voltage Vcom. It is effective to exclude electromagnetic interference caused by factors other than electromagnetic interference.

To this end, only the fluctuation of the common voltage Vcom occurring in the rising section and the falling section of the data voltage Vdata among factors generating the ripple of the common voltage Vcom in the display apparatus 100 is detected and generated in another section It is necessary to exclude the fluctuation of the common voltage Vcom.

10 is a diagram illustrating electromagnetic interference occurring in a rising or falling section of a scan signal in addition to a data voltage in a display device according to embodiments of the present invention.

As shown in FIG. 10 , a change in the common voltage Vcom may occur in a rising section and a falling section of the data voltages Vdata1 and Vdata2 , but in the rising section and falling section of the scan signal transmitted through the gate line GL. It can also occur in sections.

In the present invention, by controlling the slope level of the data voltages Vdata1 and Vdata2, electromagnetic interference occurring in the rising section and falling section of the data voltages Vdata1 and Vdata2 can be effectively reduced in the rising section and the falling section of the scan signal. It is recommended that the common voltage detection circuit 160 not detect a change in the common voltage Vcom that occurs outside the rising and falling sections of the data voltages Vdata1 and Vdata2, such as a change in the common voltage Vcom occurring in desirable.

Accordingly, the common voltage detection circuit 160 may be set to be applied with the feedback common voltage Vcom_FB only in the rising section and the falling section of the data voltages Vdata1 and Vdata2 .

The step of determining the slope level of the data voltage Vdata according to the variation value of the common voltage ( S200 ) is the data voltage Vdata corresponding to the digital common voltage variation value ADC_OUT transmitted from the common voltage detection circuit 160 . This is the process of extracting the gradient level from the lookup table (LUT).

To this end, a lookup table LUT for storing the slope level of the data voltage Vdata corresponding to the digital common voltage variation value ADC_OUT transmitted from the common voltage detection circuit 160 , and the data driving circuit 130 with reference thereto ) may include an interface circuit that transmits slope information to change the slope level of the data voltage Vdata.

11 is a block diagram illustrating a case in which a lookup table for storing a slope level of a data voltage and an interface circuit for transmitting slope information are provided in a display device according to embodiments of the present invention; FIG. 12 is a diagram illustrating an example of a lookup table for storing a plurality of slope levels corresponding to a digital common voltage variation value in a display device according to embodiments of the present invention.

First, referring to FIG. 11 , in the display apparatus 100 according to embodiments of the present invention, the timing controller 140 includes a lookup table 142 that stores the slope level of the data voltage Vdata and the slope information SI. ) may include a slope level control circuit 144 to transmit.

A plurality of slope levels corresponding to a plurality of digital common voltage variation values ADC_OUT output from the common voltage detection circuit 160 may be stored in the lookup table 142 .

Referring to FIG. 12 , the plurality of slope levels stored in the lookup table 142 is information corresponding to the slope level of the rising section or falling section of the data voltage Vdata, and corresponds to the size of the digital common voltage variation value ADC_OUT. It may be proportional or it may be inversely proportional.

For example, when the plurality of digital common voltage fluctuation values ADC_OUT output from the common voltage detection circuit 160 is 1V, electromagnetic interference occurring in the rising section or the falling section of the data voltage Vdata is relatively small. It can be determined that, when the plurality of digital common voltage variation values ADC_OUT output from the common voltage detection circuit 160 is 4V, electromagnetic interference occurring in the rising section or the falling section of the data voltage Vdata is relatively large. can be judged as

Therefore, when the digital common voltage variation value ADC_OUT is large (for example, 4V), it is determined that the difference in the slope between the rising section and the falling section of the data voltage Vdata is large, and It may be possible to increase the slope of the ascending section (Slope Level 4) to correspond to the slope.

On the other hand, when the digital common voltage variation value ADC_OUT is small (eg, 1V), it is determined that the difference between the slope of the rising section of the data voltage Vdata and the slope of the falling section is small, and the rising section of the data voltage Vdata is determined to be small. You can either keep the slope the same or increase it very small (Slope Level 1).

To this end, at this time, a separate interface signal IF is applied to the lookup table 142 and the digital common voltage variation value ADC_OUT is displayed only in the rising section and the falling section of the data voltage Vdata by using the lookup table 142 . ) may be controlled to be supplied to

That is, in a state in which the interface signal IF is applied, the lookup table 142 extracts the slope level of the data voltage Vdata corresponding to the digital common voltage variation value ADC_OUT, and slopes information ( SI) to the slope level control circuit 144 .

The slope level control circuit 144 transmits the slope control signal SC for controlling the data voltage Vdata according to the extracted slope level together with the image data DATA in accordance with the transmission start signal TS to the data driving circuit ( 130) can be forwarded. In this case, the slope control signal SC may have the same value as the slope information SI extracted from the lookup table 142 or may have different values.

Meanwhile, an interface protocol between the timing controller 140 and the data driving circuit 130 may be variously selected or defined. As an example, in the display apparatus 100 according to embodiments of the present invention, the timing controller 140 and the data driving circuit 130 using an embedded clock point-point interface (EPI) protocol ) can pass a signal between

For example, the data driving circuit 130 using the EPI protocol may directly generate a clock signal using the image data DATA received from the timing controller 140 . Accordingly, there is no need for a clock line for transmitting a clock signal between the timing controller 140 using the EPI protocol and the data driving circuit 130 .

When there are a plurality of data driving circuits 130 , the timing controller 140 performs data through a lock signal line connecting the plurality of data driving circuits 130 in series before supplying the image data DATA. A lock signal for initializing the driving circuit 130 is supplied to the first data driving circuit. The lock signal supplied to the first data driving circuit is sequentially transmitted through another second data driving circuit or the remaining data driving circuits through the lock signal line, and the lock signal is transmitted again through the lock signal line connected to the timing controller 140 . may be transmitted to the timing controller 140 .

When the lock signal is normally received through this process, the timing controller 140 supplies the image data DATA to each data driving circuit 130 through the EPI line connected 1:1 with the plurality of data driving circuits 130 . Each data driving circuit 130 converts the received image data DATA into a corresponding analog data voltage Vdata and supplies it to a corresponding display panel block to display an image through the display panel 110 . can

In the above, the case of using the Embedded clock Point-Point Interface (EPI) protocol has been described as an example, and can be used for signal transmission between the timing controller 140 and the data driving circuit 130 . The protocol may be variously changed.

Meanwhile, although the case in which the lookup table 142 and the slope level control circuit 144 are located inside the timing controller 140 has been described above as an example, they may be located inside the data driving circuit 130 or separately. It may be implemented as an integrated circuit of

The step of supplying the data voltage Vdata according to the determined slope level ( S300 ) is data supplied to the display panel 110 based on the image data DATA and the slope control signal SC transmitted from the timing controller 140 . This is a process of controlling the slope level in the rising section or the falling section of the voltage Vdata.

To this end, a slope control circuit capable of changing the slope of the data voltage Vdata in the data driving circuit 130 may be provided.

13 is a circuit diagram illustrating an example of a slope control circuit included in a data driving circuit in a display device according to embodiments of the present invention.

Referring to FIG. 13 , in the display apparatus 100 according to embodiments of the present disclosure, the output selection circuit 132 may be connected to an output buffer of the data driving circuit 130 .

The output selection circuit 132 is connected in series to a plurality of switches SW1, SW2, SW3, SW4 connected in parallel to the output buffer and each switch SW1, SW2, SW3, SW4 to have a damping resistor It may be formed of a plurality of resistors R1, R2, R3, and R4 serving as

At this time, since the resistors R1, R2, R3, R4 connected in series to each of the switches SW1, SW2, SW3, SW4 have different resistance values, the switch SW1 connected to the output buffer , SW2, SW3, and SW4), the slope level of the data voltage Vdata transmitted through the output selection circuit 132 may be changed according to a turned-on switch.

Accordingly, the switches SW1 , SW2 , SW3 , and SW4 constituting the output selection circuit 132 are turned on by the slope control signal SC transmitted from the timing controller 140 .

14 is a signal waveform diagram illustrating an example of changing a slope level of a data voltage according to a variation value of a common voltage in a display device according to embodiments of the present invention.

Referring to FIG. 14 , the variation value of the common voltage Vcom increases due to electromagnetic interference occurring in the rising section and the falling section of the data voltages Vdata1 and Vdata2 in the display device 100 according to embodiments of the present invention. In this case, it may be determined that the difference between the slope levels of the rising section and the falling section of the data voltages Vdata1 and Vdata2 is large.

Accordingly, the slope level in the rising section of the data voltages Vdata1 and Vdata2 is increased (eg, Slope Level 2 or Slope Level 3), by reducing the difference between the slope levels of the rising section and the falling section of the data voltages Vdata1 and Vdata2, electromagnetic interference can be reduced.

Meanwhile, in the above description, a case in which the slope level in the rising section of the data voltage Vdata is changed in order to reduce electromagnetic interference in the rising section and the falling section of the data voltage Vdata has been described as an example, but on the contrary, the data voltage The slope level in the falling section of (Vdata) may be changed to correspond to the slope level in the rising section.

However, in the case of the display device 100, in order to reduce heat generation of the sub-pixels SP to which the data voltage Vdata is supplied during the display driving period, the slope level is intentionally decreased in the rising section, and the adjacent data voltage ( Considering that the slope level in the falling section is increased so that Vdata) does not overlap, it may be effective to control the slope level in the rising section of the data voltage Vdata in order to reduce electromagnetic interference.

The above description is merely illustrative of the technical spirit of the present invention, and various modifications and variations will be possible without departing from the essential characteristics of the present invention by those skilled in the art to which the present invention pertains. In addition, since the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, the scope of the technical spirit of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

display device
110: display panel
120: gate driving circuit
130: data driving circuit
132: output selection circuit
140: timing controller
142: lookup table
144: slope level control circuit
150: touch driving circuit
160: common voltage detection circuit
162: analog-to-digital converter

Claims (18)

a display panel in which a plurality of subpixels are disposed, a common voltage line for applying a common voltage to a common electrode and a feedback line through which a feedback common voltage fed back through the common electrode is transmitted;
a common voltage detection circuit for detecting a common voltage variation value through the feedback line;
a slope level control circuit for determining a slope level of the data voltage corresponding to the common voltage variation value; and
and an output selection circuit configured to change a slope level of the data voltage supplied to the display panel to correspond to the determined slope level.
The method of claim 1,
The feedback line is
A display device positioned adjacent to the common voltage line on a side surface of the display panel or positioned in a loop shape along a non-display area surrounding a display area of the display panel.
The method of claim 1,
The common voltage detection circuit is
an operational amplifier comparing the feedback common voltage and a reference common voltage; and
and an analog-to-digital converter for converting a common voltage variation output through the operational amplifier into a digital value.
4. The method of claim 3,
The operational amplifier is
and a capacitor connected between the inverting input terminal and the output terminal, receiving the feedback common voltage to an inverting input terminal, receiving a reference common voltage to a non-inverting input terminal.
4. The method of claim 3,
The analog-to-digital converter is
a plurality of resistors connected in series to branch a reference voltage;
a plurality of comparators comparing the common voltage variation value with the branched reference voltage; and
and an encoder for converting the output value of the comparator into a digital signal.
The method of claim 1,
The common voltage detection circuit is
A display device configured to detect the common voltage variation value in a rising section or a falling section of the data voltage.
The method of claim 1,
The common voltage detection circuit is
A display device located in a data driving circuit that supplies the data voltage to the display panel.
The method of claim 1,
The slope level control circuit is
extracting a corresponding slope level from a lookup table according to the digital common voltage fluctuation value output from the common voltage detection circuit;
A display device that transmits a slope control signal for controlling the data voltage according to the extracted slope level.
The method of claim 1,
The slope level control circuit is
A display device located in a timing controller that controls a data driving circuit for supplying the data voltage to the display panel.
The method of claim 1,
The output selection circuit is
located in a data driving circuit that supplies the data voltage to the display panel;
a plurality of switches connected in parallel to an output buffer of the data driving circuit; and
and a plurality of damping resistors connected in series to each of the plurality of switches.
The method of claim 1,
The slope level of the data voltage is
A display device that is changed in a rising period of the data voltage.
12. The method of claim 11,
As the common voltage variation value increases, a slope level in a rising period of the data voltage is greatly increased.
A display comprising: a display panel including a common voltage line for applying a common voltage to a common electrode and a feedback line through which a feedback common voltage fed back through the common electrode is transmitted; and a data driving circuit for supplying a data voltage to the display panel A method of driving a device, comprising:
detecting a change in a common voltage transmitted through the feedback line;
determining a slope level of the data voltage applied to the display panel according to the common voltage variation value; and
and supplying the data voltage to the display panel according to the determined inclination level.
14. The method of claim 13,
The step of detecting a change in the common voltage includes:
comparing the feedback common voltage and a reference common voltage; and
and converting a common voltage variation value generated according to the comparison result into a digital value.
14. The method of claim 13,
The step of detecting a change in the common voltage includes:
A method of driving a display device for detecting the common voltage variation value in a rising section or a falling section of the data voltage.
14. The method of claim 13,
The step of determining the gradient level is
extracting a corresponding slope level from a lookup table according to the common voltage variation value; and
and transmitting a slope control signal for controlling the data voltage according to the extracted slope level.
14. The method of claim 13,
The slope level of the data voltage is
A method of driving a display device that is changed in a rising period of the data voltage.
18. The method of claim 17,
A method of driving a display apparatus for greatly increasing a slope level in a rising period of the data voltage as the common voltage variation value increases.

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