Pixel voltage compensation circuit and method

Abstract

The disclosed embodiments provide a pixel voltage compensation circuit and method to prevent horizontal streaks. The pixel voltage compensation circuit includes a voltage difference acquisition circuit and a data voltage correction circuit. The voltage difference acquisition circuit is electrically connected to a common electrode line via a connection portion, and is used to monitor fluctuations in the common voltage in real time to obtain the difference between the current common voltage and a reference common voltage. The number of connection portions is less than the number of common electrode lines. The data voltage correction circuit is used to compensate the data voltage in real time using the difference to ensure that the pixel voltage remains stable. The pixel voltage is the difference between the data voltage and the common voltage.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to, but are not limited to, the field of display technology, and in particular to a pixel voltage compensation circuit and method. Background Art

[0002] The common electrode of an LCD (Liquid Crystal Display) is usually maintained at a specific potential. The driving signal (data signal) sent through the data line is transmitted to the pixel electrode, so that an electric field is formed between the pixel electrode and the common electrode to drive the deflection of the liquid crystal molecules, thereby realizing the image display.

[0003] TDDI (Touch and Display Driver Integration) integrates the touch chip and display chip into a single chip. The touch display panel using TDDI divides the common electrode layer (com layer) into multiple touch units, or sensor blocks. The sensor blocks use time-sharing multiplexing technology, that is, during the display period, they act as common electrodes, providing common voltage signals to display the screen, and during the touch period, they act as touch electrodes, providing touch signals, to achieve the effect of both touch and display. However, the level recovery capabilities of sensor blocks in different rows are different, which will cause horizontal stripes on the display, which are called sensor stripes.

[0004] In addition, when a touch panel (TP) has signal disturbance during detection, horizontal stripes may also be caused, which are called TP horizontal stripes. Summary of the Invention

[0005] The embodiments of the present disclosure provide a pixel voltage compensation circuit and method to avoid the occurrence of horizontal stripes.

[0006] In one aspect, an embodiment of the present disclosure provides a pixel voltage compensation circuit, comprising a voltage difference acquisition circuit and a data voltage correction circuit, wherein:

[0007] The voltage difference acquisition circuit is electrically connected to the common electrode line through a connecting portion, and is used to monitor the fluctuation of the common voltage in real time and obtain the difference between the current common voltage and the reference common voltage. The number of the connecting portions is less than the number of the common electrode lines.

[0008] The data voltage correction circuit is used to compensate the data voltage in real time using the difference to ensure that the pixel voltage remains stable. The pixel voltage is the difference between the data voltage and the common voltage.

[0009] In an exemplary embodiment, the voltage difference acquisition circuit is a differential circuit composed of a first operational amplifier.

[0010] In an exemplary embodiment, the first input terminal of the voltage difference acquisition circuit receives the current common voltage signal and is connected to the inverting input terminal of the first operational amplifier through a first resistor. The second input terminal of the voltage difference acquisition circuit receives the reference common voltage signal and is connected to the non-inverting input terminal of the first operational amplifier through a second resistor. The inverting input terminal of the first operational amplifier is connected to the input terminal of the first operational amplifier through a third resistor. The non-inverting input terminal of the first operational amplifier is grounded through a fourth resistor. The output signal of the output terminal of the first operational amplifier is the difference between the current common voltage signal and the reference common voltage signal.

[0011] In an exemplary embodiment, the first resistor, the second resistor, the third resistor, and the fourth resistor have the same resistance value.

[0012] In an exemplary embodiment, the data voltage correction circuit is a non-inverting summing circuit composed of a second operational amplifier.

[0013] In an exemplary embodiment, the first input terminal of the data voltage correction circuit is connected to the output terminal of the voltage difference acquisition circuit, and is connected to the non-inverting input terminal of the second operational amplifier through a fifth resistor. The second input terminal of the data voltage correction circuit receives the current data voltage signal, and is connected to the non-inverting input terminal of the second operational amplifier through a sixth resistor. The non-inverting input terminal of the second operational amplifier is grounded through a ninth resistor. The inverting input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier through a seventh resistor, and is connected to the negative voltage signal through an eighth circuit. The voltage terminal of the second operational amplifier is connected to the positive voltage signal, and the ground terminal of the second operational amplifier is connected to the negative voltage signal.

[0014] In an exemplary embodiment, the fifth resistor, the sixth resistor, the seventh resistor, and the eighth resistor have the same resistance value, and at least one resistor is twice as great as the ninth resistor.

[0015] In an exemplary embodiment, the relationship between the resistance accuracy ΔR, the maximum error of the data voltage, and the common voltage value satisfies the following formula requirements:

[0016]

[0017] Wherein, ΔVsource error is the maximum error of the data voltage, m=(1+ΔR) / (1-ΔR), Vcom′ is the common voltage reference value, and Vcom is the current common voltage value.

[0018] On the other hand, an embodiment of the present disclosure further provides a pixel voltage compensation method, including:

[0019] The voltage difference acquisition circuit monitors the fluctuation of the common voltage in real time to obtain the difference between the current common voltage and the reference common voltage;

[0020] The data voltage correction circuit receives the difference and uses the difference to compensate the data voltage in real time to ensure that the pixel voltage remains stable. The pixel voltage is the difference between the data voltage and the common voltage.

[0021] In an exemplary embodiment, before monitoring the fluctuation of the common voltage in real time by the voltage difference acquisition circuit, the method further includes:

[0022] When it is determined that the current period is the display period, the voltage difference acquisition circuit is used to monitor the fluctuation of the common voltage in real time.

[0023] On the other hand, an embodiment of the present disclosure further provides a display panel including the aforementioned pixel voltage compensation circuit.

[0024] On the other hand, an embodiment of the present disclosure further provides a display device, comprising the aforementioned display panel.

[0025] The exemplary embodiments of the present disclosure disclose a pixel voltage compensation circuit and method, a display panel, and a display device. The circuit detects the common voltage value in real time and uses the difference between the actual value of the common voltage and the reference value to compensate the data voltage. The circuit does not occupy the computing power of the IC chip, has a fast computing speed, can compensate the pixel voltage row by row, and the compensation area is not restricted.

[0026] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purposes and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are intended to provide a further understanding of the technical solutions of the present disclosure and constitute a part of the specification. Together with the embodiments of the present disclosure, they are used to explain the technical solutions of the present disclosure and do not constitute a limitation of the technical solutions of the present disclosure. The shapes and sizes of the components in the drawings do not reflect the actual scale and are intended only to illustrate the contents of the present disclosure.

[0028] Figure 1 This is a circuit diagram of a sub-pixel of an LCD panel;

[0029] Figure 2 The schematic diagram of the sensor stripe formation;

[0030] Figure 3 This is the schematic diagram of the TP stripe formation;

[0031] Figure 4 Schematic diagram of horizontal stripes;

[0032] Figure 5 is a schematic diagram of a pixel voltage compensation circuit according to an embodiment of the present disclosure;

[0033] Figure 6 Schematic diagram of a planar structure of an array substrate;

[0034] Figure 7 This is a schematic diagram of the connection between the pixel voltage compensation circuit and the data driver according to an embodiment of the present disclosure;

[0035] Figure 8 This is a schematic diagram of the connection between a voltage difference acquisition circuit and a common electrode line according to an embodiment of the present disclosure;

[0036] Figure 9 A flowchart of a pixel voltage compensation method provided by an embodiment of the present disclosure;

[0037] Figure 10 A schematic diagram of an example pixel voltage compensation circuit;

[0038] Figure 11 A flowchart of an example pixel voltage compensation method for application;

[0039] Figure 12 The circuit diagram of the pixel voltage compensation circuit of the application example;

[0040] Figure 13 Schematic diagram of a pixel without horizontal stripes after compensation by the pixel voltage compensation circuit. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the present disclosure clearer, the embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Note that the embodiments can be implemented in a variety of different forms. A person of ordinary skill in the art can easily understand the fact that the methods and contents can be transformed into various forms without departing from the purpose and scope of the present disclosure. Therefore, the present disclosure should not be interpreted as being limited to the contents described in the following embodiments. In the absence of conflict, the embodiments in the present disclosure and the features in the embodiments can be arbitrarily combined with each other.

[0042] In the drawings, the sizes of various components, layer thicknesses, or regions may be exaggerated for clarity. Therefore, one embodiment of the present disclosure is not necessarily limited to these dimensions, and the shapes and sizes of the components in the drawings do not reflect true proportions. Furthermore, the drawings schematically illustrate idealized examples, and one embodiment of the present disclosure is not limited to the shapes or numerical values ​​shown in the drawings.

[0043] In this specification, ordinal numbers such as “first”, “second” and “third” are provided to avoid confusion among constituent elements, and are not intended to limit the number.

[0044] In this specification, for convenience, words and phrases indicating orientation or positional relationships, such as "middle," "upper," "lower," "front," "back," "vertical," "horizontal," "top," "bottom," "inside," and "outside," are used to illustrate the positional relationships of constituent elements with reference to the accompanying drawings. This is merely for the purpose of facilitating the description of this specification and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present disclosure. The positional relationships of constituent elements may be appropriately changed depending on the direction in which each constituent element is described. Therefore, the present disclosure is not limited to the words and phrases described in the specification and may be appropriately replaced according to the circumstances.

[0045] In this specification, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they can refer to fixed, removable, or integral connections; mechanical or electrical connections; direct connections, indirect connections through intermediaries, or internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in this disclosure.

[0046] In this specification, a transistor refers to a device that includes at least three test terminals: a gate electrode, a drain electrode, and a source electrode. A transistor has a channel region between a drain electrode (drain electrode test terminal, drain region, or drain electrode) and a source electrode (source electrode test terminal, source region, or source electrode), and current can flow through the drain electrode, the channel region, and the source electrode. Note that in this specification, the channel region refers to the region through which current primarily flows.

[0047] In this specification, the first electrode can be a drain electrode and the second electrode can be a source electrode, or vice versa. The functions of "source electrode" and "drain electrode" may be interchanged when using transistors with opposite polarity or when the direction of current changes during circuit operation. Therefore, in this specification, "source electrode" and "drain electrode" may be interchanged.

[0048] In this specification, "electrically connected" includes components connected together via an element having some electrical function. There are no particular limitations on the "element having some electrical function" as long as it enables the transfer of electrical signals between the connected components. Examples of "element having some electrical function" include not only electrodes and wiring, but also switching elements such as transistors, resistors, inductors, capacitors, and other components with various functions.

[0049] Since the pixel voltage is the voltage difference between Vcom and Vsource, it directly determines the brightness of the pixel. When Vcom is pulled by other signals due to coupling and cannot be restored in time, it will cause abnormal voltage of one or several rows of pixels, resulting in the appearance of horizontal stripes. The details are as follows:

[0050] Figure 1 This is a circuit structure diagram of a sub-pixel of an LCD panel. In the figure, T1 is a switching transistor (TFT), including a gate G, a source S, and a drain D. Clc is a liquid crystal, and Cs is a storage capacitor. The liquid crystal is connected in parallel with the storage capacitor, which is used to maintain the pixel voltage during the period when the gate signal (Gate signal) is turned off to ensure normal display. When the gate signal controls the TFT to turn on, the source voltage on the data line charges the liquid crystal and the storage capacitor. The voltage difference across the liquid crystal is the voltage difference between Vsource and Vcom. When Vcom is disturbed, it will cause abnormal voltage across the liquid crystal, abnormal pixel transmittance, and the formation of horizontal stripes. Horizontal stripes can be divided into sensor horizontal stripes and TP horizontal stripes. For the formation mechanism of sensor horizontal stripes, please refer to Figure 1 and Figure 2 There is a large coupling capacitance between the gate line and the common electrode layer (the layer where the Vcom line is located). Therefore, when the screen is displayed, the common voltage Vcom will be affected by the opening and closing of the Gate signal, generating a coupling voltage. The jump of the TFT gate switch signal on the Gate line will pull the Vcom level through coupling, such as Figure 2 As shown in the figure, when the Gate signal jumps to a high level, the coupling effect pulls Vcom up. When the Gate signal returns to a low level, it pulls Vcom down. The above Vcom voltage change will cause the pixel voltage to not charge to the target value. It can be seen that due to the complex signals in the panel and the different pulling effects, the display brightness of different rows varies, thus forming horizontal stripes. The formation mechanism of TP horizontal stripes is shown in Figure 3 During the TP period, the Vcom line will send a detection signal for touch detection. The detection signal is ideally a square wave signal, but due to the heavy load on the panel, the signal has a tailing phenomenon. After the TP period, the Vcom has not recovered. Figure 3 The position indicated by the middle arrow causes abnormal voltage of one or several rows of pixels after the TP time period, which appears as TP horizontal stripes.

[0051] It can be seen that due to the instability of Vcom, the voltage difference between Vsource and Vcom changes, which leads to the appearance of horizontal stripes. Figure 4As shown in FIG. 1 , for row N+1, the voltage difference Vclc_N+1 between Vsource and Vcom decreases due to the fluctuation of Vcom, resulting in a dark line on the display. For row N+M, the voltage difference Vclc_N+M between Vsource and Vcom increases due to the fluctuation of Vcom, resulting in a bright line on the display.

[0052] Currently, one solution to compensate for horizontal streaks caused by Vcom recovery issues is to add Vcom detection drivers within the IC chip and decoupling correction wiring and decoupling switches within the panel to offset the gate signal's pull on Vcom, preventing timely recovery. This solution has the following issues: ① It requires additional panel wiring, increasing design complexity and sacrificing panel transmittance; ② Horizontal streaks are not only caused by the gate line pulling Vcom, but also by the TDDI IC's own Vcom drive signal during the touch zone, which can fail to recover to the Vcom level in time after entering the display area, thus causing horizontal streaks. This solution has a limited scope of application.

[0053] Another compensation solution is to determine the adjustment range of the compensation voltage based on the voltage range of Vcom deviation, and the compensation method is achieved by changing the source data. The problems with this solution are: ① It can only compensate for a specific area of ​​a specific screen, which has a narrow application scenario; ② It requires the recognition and calculation of the next frame of data, which consumes a lot of IC computing resources and takes a long time to calculate; ③ Compensation by correcting the source voltage has low accuracy and horizontal stripes may still exist. Figure 3 The Vcom voltage fluctuates within one line of source charging time, but what really affects the pixel display is the Vcom voltage immediately before the gate TFT turns off. This requires the IC to accurately collect the Vcom voltage immediately before the gate TFT turns off and correct the source data. However, with current technology, it is difficult to accurately collect this voltage, and calculation and correction through the IC takes a certain amount of time. This will result in low accuracy in the method of correcting the source data after IC processing.

[0054] According to the above-mentioned mechanism of horizontal stripe formation, the formation of horizontal stripes is mainly due to the incomplete recovery of the Vcom voltage, which causes the voltage difference between Vcom and Vsource to be unstable. Based on this, the embodiment of the present disclosure provides a pixel voltage compensation circuit, such as Figure 5 As shown, it includes a voltage difference acquisition circuit and a data voltage correction circuit, wherein:

[0055] The voltage difference acquisition circuit is electrically connected to the common electrode line through a connecting portion, and is used to monitor the fluctuation of the common voltage in real time and obtain the difference between the current common voltage and the reference common voltage. The number of the connecting portions is less than the number of the common electrode lines.

[0056] The data voltage correction circuit is used to compensate the data voltage in real time using the difference to ensure that the difference between the data voltage and the common voltage, ie, the pixel voltage, remains stable.

[0057] The electrical connection with the common electrode line via the connection portion includes any one of the following ways: direct connection with the common electrode line, where the connection portion may be a connection wire; or connection with the common electrode line via a driver chip, where the connection portion may include a driver chip and a connection wire.

[0058] The pixel voltage compensation circuit described in the embodiment of the present disclosure detects the common voltage value in real time and uses the difference between the actual value of the common voltage and the reference value to compensate the data voltage. This does not occupy the computing power of the IC chip, has a fast computing speed, can compensate the pixel voltage row by row, and the compensation area is not restricted.

[0059] In an exemplary embodiment, the voltage difference acquisition circuit is a differential circuit composed of a first operational amplifier. Specifically, the first input terminal of the voltage difference acquisition circuit receives the current common voltage signal and is connected to the inverting input terminal of the first operational amplifier through a first resistor. The second input terminal of the voltage difference acquisition circuit receives the reference common voltage signal (or preset common voltage signal) and is connected to the non-inverting input terminal of the first operational amplifier through a second resistor. The inverting input terminal of the first operational amplifier is connected to the input terminal of the first operational amplifier through a third resistor. The non-inverting input terminal of the first operational amplifier is grounded through a fourth resistor. The signal output by the output terminal of the first operational amplifier is the difference between the current common voltage signal and the reference common voltage signal. Optionally, the resistance values ​​of the first resistor, the second resistor, the third resistor and the fourth resistor are the same. The same as described herein includes exactly the same and approximately the same (the original value fluctuates up and down by a predetermined ratio). For example, when R2 = (80%-120%) R1 or R2 = (90%-110%) R1, R2 is considered to be the same as R1.

[0060] In an exemplary embodiment, the data voltage correction circuit is a non-inverting summing circuit composed of a second operational amplifier. Specifically, a first input terminal of the data voltage correction circuit is connected to the output terminal of the voltage difference acquisition circuit, that is, receives the difference between the current common voltage signal and the reference common voltage signal, and is connected to the non-inverting input terminal of the second operational amplifier through a fifth resistor. A second input terminal of the data voltage correction circuit receives the current data voltage signal and is connected to the non-inverting input terminal of the second operational amplifier through a sixth resistor. The non-inverting input terminal of the second operational amplifier is grounded through a ninth resistor. The inverting input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier through a seventh resistor and is connected to the negative voltage signal (AVEE) of the display panel through an eighth circuit. The voltage terminal of the second operational amplifier is connected to the positive voltage signal (AVDD) of the display panel, and the ground terminal of the second operational amplifier is connected to the negative voltage signal (AVEE) of the display panel. Optionally, the resistance values ​​of the fifth, sixth, seventh, and eighth resistors are the same, and at least one resistor is equal to twice that of the ninth resistor. Preferably, the resistance values ​​of the fifth, sixth, seventh, and eighth resistors are all equal to twice that of the ninth resistor.

[0061] In an exemplary embodiment, the resistor accuracy can be selected in the following manner: the resistor accuracy ΔR is selected so that the maximum error of the data voltage does not exceed the voltage of one grayscale and the common voltage value is within the operating range. The relationship between the resistor accuracy ΔR, the maximum error of the data voltage, and the common voltage value satisfies the following formula:

[0062]

[0063] Wherein, ΔVsource error is the maximum error of the data voltage, m=(1+ΔR) / (1-ΔR), Vcom′ is the common voltage reference value, and Vcom is the current common voltage value.

[0064] By selecting the resistor accuracy in the above manner, the data voltage fluctuation can be ensured to be less than the voltage of one grayscale while meeting the common voltage design requirements, thereby avoiding changes in display brightness and further preventing the appearance of horizontal stripes.

[0065] Figure 6 FIG. 1 is a schematic diagram of a planar structure of an array substrate. Figure 6As shown, in an exemplary embodiment, the array substrate includes a display area and a frame area. The display area may include a plurality of gate lines (S1 to Sm) and a plurality of data lines (D1 to Dn), namely Vsource lines. The plurality of gate lines may extend in the horizontal direction and be sequentially arranged in the vertical direction. The plurality of data lines may extend in the vertical direction and be sequentially arranged in the horizontal direction. The plurality of gate lines and the plurality of data lines that intersect each other define a plurality of regularly arranged sub-pixels Pxij. i and j may be natural numbers. In an exemplary embodiment, as Figure 1 As shown, at least one sub-pixel Pxij may include a thin film transistor T1, a pixel electrode, and a common electrode. The thin film transistor is connected to the gate line, the data line, and the pixel electrode, respectively. The array substrate also includes common electrode lines (E1 to Eo in the figure). The common electrode lines can extend horizontally and are arranged in sequence along the vertical direction. The common electrode lines are correspondingly connected to the common electrodes in multiple sub-pixels Pxij.

[0066] The first input end of the voltage difference acquisition circuit is connected to the common electrode line to receive the current common voltage signal, and the second input end of the data voltage correction circuit is respectively connected to multiple output ports of the data driver for receiving the current data voltage signal and outputting the output signal to multiple data signal lines. A connection method is as follows Figure 7 In other examples, other connection modes may also be used, and this disclosure does not limit this.

[0067] Figure 8 A schematic diagram of a connection method between a voltage difference acquisition circuit and a common electrode line is given. In the figure, the imth row is a pixel row. There are k common electrode lines on the display panel. However, when the voltage detection circuit detects the common voltage, it does not need to be connected to each common electrode line. It only needs to be connected to one or several of the k common electrode lines. Taking the connection with one common electrode line as an example, the voltage difference acquisition circuit does not need to obtain the voltage of each common electrode line. It only needs to obtain the voltage of one common electrode line. There is no need for multiple or partitioned monitoring. The monitoring and calculation speed is fast, the response is quick and sensitive, and it can better meet the needs of real-time calculation. The example of connecting the voltage difference acquisition circuit to one common electrode line minimizes the calculation process to the greatest extent, avoids calculation errors, and reduces the complexity of the circuit. Since multiple wiring is not required, the overall circuit occupies less space and the process is simpler.

[0068] In other embodiments, the voltage difference acquisition circuit may also directly lead a connection line from the driver IC to obtain the common voltage value.

[0069] Figure 9 A schematic diagram of a pixel voltage compensation method provided by an embodiment of the present disclosure is shown in the figure. The method includes the following steps:

[0070] Step 11: monitor the fluctuation of the common voltage in real time through the voltage difference acquisition circuit to obtain the difference between the current common voltage and the reference common voltage;

[0071] Step 12: receiving the difference through a data voltage correction circuit, and using the difference to compensate the data voltage in real time, so that the difference between the data voltage and the common voltage, that is, the pixel voltage, remains stable.

[0072] The pixel voltage compensation method described in the embodiment of the present disclosure detects the common voltage value in real time and uses the difference between the actual value of the common voltage and the reference value to compensate the data voltage. This method does not occupy the computing power of the IC chip, has a fast computing speed, can compensate the pixel voltage row by row, and has no limitation on the compensation area.

[0073] In an exemplary embodiment, to conserve resources, considering that the common electrode lines are also multiplexed as touch signal lines, the compensation operation can be performed only during the display period, and not during the touch period. The method can also include step 10, before step 11, to determine whether the current period is a display period. If so, step 11 is executed. If not, i.e., the current period is a touch period, the normal process is followed, and pixel voltage compensation is not performed.

[0074] In circuit implementation, a data selector can be added to achieve this. When the current period is display, the data signal is input into the pixel voltage compensation circuit for compensation, and the output signal is output to the data signal line. When the current period is touch, the data signal is directly output to the data signal line.

[0075] The compensation method and compensation circuit are described below through an application example.

[0076] Figure 10 This is a schematic diagram of the pixel voltage compensation circuit in this application example. The original Vsource in the figure represents the raw data voltage, the new Vsource represents the compensated data voltage, the Vcom line represents the current real-time common voltage value on the common voltage line, the Vcom set value represents the preset reference common voltage value, and TP_EN is the touch enable signal. In this example, a high level of the touch enable signal represents the touch time (T in the figure), and a low level of the touch enable signal represents the display time (D in the figure). The Vcom voltage difference acquisition module in the figure is the aforementioned voltage difference acquisition circuit, and the source voltage correction module in the figure is the aforementioned data voltage correction circuit.

[0077] Compensation methods such as Figure 11As shown, the touch enable signal is determined to be high. If so, the Vcom voltage difference acquisition module calculates the difference ΔVcom (abbreviated as ΔV in the figure) between the set Vcom value and the measured Vcom' (Vcom line). This difference is then compensated to the Source voltage by the source voltage correction module. If not, no compensation is performed, and Vsource remains at its original value. If the current Vcom voltage exceeds its set value due to coupling, the source voltage should also be increased in a synchronous manner to eliminate the pixel voltage anomaly caused by Vcom fluctuations. In this case, the compensated source voltage Vsource' = Vsource + ΔVcom, where ΔVcom = Vcom' - Vcom. Since most current display panels use TDDI ICs, Vcom serves as the pixel common electrode in the display area. In the touch area, Vcom is reused as the sensor block's drive signal, or detection signal, for sensing the touch position of a finger or active pen tip. In this case, Vcom is not used as a display electrode. Therefore, the pixel voltage compensation circuit is disabled during the touch area, and no source voltage compensation is applied.

[0078] In this embodiment, the circuit diagram of the pixel voltage compensation circuit is as follows: Figure 12 As shown, Vcom' is the current Vcom value on the Vcom line in the panel. The Vcom line is located in the common electrode layer and is formed by ITO (Indium-Tin Oxide, indium tin oxide - a transparent conductive film). The current Vcom is connected to the input end of the compensation circuit through a lead to sense the current Vcom voltage value. Vcom is the set Vcom. AVDD and AVEE are the input power supplies of the panel, where AVDD is the positive power supply and AVEE is the negative power supply. Vsource is the original data voltage on the data line, and Vsource' is the compensated data voltage. Resistors R1, R2, R3, and R4 together with the first op amp U1A form a differential circuit for calculating the difference △Vcom between the Vcom set value and the current measured value Vcom'. Resistors R5, R6, R7, R8, and R9 together with the second op amp U1B form a same-direction summing circuit for compensating the data voltage. The values ​​of resistors R1 to R4 refer to the following formula:

[0079]

[0080] Here, R1=R2=R3=R4, and the above formula can be simplified to ΔVcom=×Vcom′-Vcom.

[0081] Similarly, the values ​​of the resistors R5-R8 can be determined by referring to the following formula:

[0082]

[0083] Among them, R′=R5 / / R6 / / R9, and “ / / ” represents parallel connection.

[0084] Here, R5=R6=R7=R8=2R9, and the above formula can be simplified to Source′=Vsource+ΔVcom.

[0085] When the data voltage fluctuates by more than 15mV (the fluctuation value exceeds the voltage of one grayscale, and can be other values ​​in other examples), brightening or dimming will occur, so there are more stringent requirements for the selection of resistor specifications.

[0086] Assuming the resistance error is △R, the maximum value of R1 is R1(1+△R) and the minimum value is R1(1-△R). At the same time, taking R1=R2=R3=R4=R5, the maximum error of formula (1) is as follows:

[0087]

[0088] make Then formula (3) can be simplified as:

[0089] ΔVcom error = (m 2 -1)Vcom′-(m-1)Vcom Formula (4)

[0090] R'=R5 / / R6 / / R9=1 / 3(R1+△R). According to formula (2), the difference in pixel voltage △source comes from:

[0091]

[0092] Combining formula (4), the △Vsource error can be obtained as:

[0093]

[0094] Typically, the voltage difference between Vcom' and Vcom is within 100mV. Here, we use the maximum value as an example, i.e., Vcom' - Vcom = 100mV. Common resistor accuracies are 5%, 1%, 0.5%, etc. When selecting a 1% resistor accuracies, m = 1.02, and we can obtain:

[0095] △Vsource error = 28.28 + 0.14Vcom Formula (7)

[0096] As described above, the fluctuation of the source voltage needs to be less than 15 mV, that is, -15 mV < △Vsource error < 15 mV. At this time, the solution of formula (7) is: -288.5 mV < Vcom < -88.5 mV. In fact, the Vcom voltage is much less than -288.5 mV, and the reasonable range should be -2000 mV to 0 mV. Therefore, the 1% precision resistor cannot meet the requirements. Similarly, when the resistor precision is selected to be 0.5%, it is solved that -2404 mV < Vcom < 2007 mV, which meets the design requirements. Therefore, the above resistor precision should be controlled within 0.5%.

[0097] As can be seen from the above formula, the power supply voltage can be automatically adjusted according to the fluctuation of Vcom, always keeping the voltage difference between Vsource and Vcom unchanged. The compensated pixel voltage does not fluctuate with the fluctuation of Vcom, thus achieving the purpose of eliminating sensor stripes or TP stripes, as Figure 13 shown.

[0098] In the embodiment of the present disclosure, the fluctuation of the Vcom voltage in the display area is monitored in real time, and the pixel voltage is compensated row by row in a timely manner. The compensation circuit is designed in the form of a pure analog circuit, automatically calculating the Vcom difference and compensating the pixel voltage, without the participation of a driver chip (Driver IC) in the calculation, with a fast response speed, and can perform real-time row-by-row compensation on the pixel voltage.

[0099] The pixel voltage compensation device and method in the solution of the present disclosure are particularly related to the situation where the loading of the display panel is large and the Vcom voltage cannot be restored in time, resulting in sensor stripes and TP stripes. The applicable product types include, but are not limited to, LCD panels with backplane materials of a-si, oxide, and ltps.

[0100] The present disclosure also provides a display panel, including the pixel voltage compensation circuit of the foregoing embodiment.

[0101] The present disclosure also provides a display device, including the display panel of the foregoing embodiment. The display device can be: any product or component with a display function such as a mobile phone, a tablet computer, a television, a monitor, a notebook computer, a digital photo frame, or a navigator.

[0102] Although the disclosed embodiments are as above, the content described is only an embodiment adopted for the convenience of understanding the present disclosure, and is not used to limit the present disclosure. Any person skilled in the art within the scope of the present disclosure can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed by the present disclosure. However, the scope of patent protection of this application shall still be subject to the scope defined by the appended claims.

Claims

1. A pixel voltage compensation circuit, characterized in that: It includes a voltage difference acquisition circuit and a data voltage correction circuit, wherein: The voltage difference acquisition circuit is electrically connected to the common electrode line through a connecting portion, and is used to monitor the fluctuation of the common voltage in real time and obtain the difference between the current common voltage and the reference common voltage. The number of the connecting portions is less than the number of the common electrode lines. The data voltage correction circuit is used to compensate the data voltage in real time using the difference to ensure that the pixel voltage remains stable, where the pixel voltage is the difference between the data voltage and the common voltage; wherein: The voltage difference acquisition circuit is a differential circuit composed of a first operational amplifier; a first input terminal of the voltage difference acquisition circuit receives a current common voltage signal and is connected to an inverting input terminal of the first operational amplifier through a first resistor; a second input terminal of the voltage difference acquisition circuit receives a reference common voltage signal and is connected to a non-inverting input terminal of the first operational amplifier through a second resistor; an inverting input terminal of the first operational amplifier is connected to an input terminal of the first operational amplifier through a third resistor; and a non-inverting input terminal of the first operational amplifier is grounded through a fourth resistor; an output signal of the output terminal of the first operational amplifier is a difference between the current common voltage signal and the reference common voltage signal; The relationship between the resistance accuracy ΔR, the maximum error of the data voltage, and the common voltage value satisfies the following formula requirements: Wherein, ΔVsource error is the maximum error of the data voltage, m=(1+ΔR) / (1-ΔR), Vcom′ is the common voltage reference value, and Vcom is the current common voltage value.

2. The pixel voltage compensation circuit according to claim 1, wherein: The first resistor, the second resistor, the third resistor and the fourth resistor have the same resistance value.

3. The pixel voltage compensation circuit according to claim 1, wherein: The data voltage correction circuit is a common-phase summing circuit composed of a second operational amplifier.

4. The pixel voltage compensation circuit according to claim 3, wherein: The first input end of the data voltage correction circuit is connected to the output end of the voltage difference acquisition circuit, and is connected to the non-inverting input end of the second operational amplifier through the fifth resistor. The second input end of the data voltage correction circuit receives the current data voltage signal, and is connected to the non-inverting input end of the second operational amplifier through the sixth resistor. The non-inverting input end of the second operational amplifier is grounded through the ninth resistor. The inverting input end of the second operational amplifier is connected to the output end of the second operational amplifier through the seventh resistor, and is connected to the negative voltage signal through the eighth circuit. The voltage end of the second operational amplifier is connected to the positive voltage signal, and the ground end of the second operational amplifier is connected to the negative voltage signal.

5. The pixel voltage compensation circuit according to claim 4, wherein: The fifth resistor, the sixth resistor, the seventh resistor and the eighth resistor have the same resistance value, and at least one resistor is equal to twice the resistance of the ninth resistor.

6. A pixel voltage compensation method, comprising: The voltage difference acquisition circuit monitors the fluctuation of the common voltage in real time to obtain the difference between the current common voltage and the reference common voltage; The data voltage correction circuit receives the difference and uses the difference to compensate the data voltage in real time to ensure that the pixel voltage remains stable, where the pixel voltage is the difference between the data voltage and the common voltage; Wherein: the voltage difference acquisition circuit is a differential circuit composed of a first operational amplifier; the first input end of the voltage difference acquisition circuit receives a current common voltage signal and is connected to the inverting input end of the first operational amplifier through a first resistor; the second input end of the voltage difference acquisition circuit receives a reference common voltage signal and is connected to the non-inverting input end of the first operational amplifier through a second resistor; the inverting input end of the first operational amplifier is connected to the input end of the first operational amplifier through a third resistor; the non-inverting input end of the first operational amplifier is grounded through a fourth resistor; and the output end of the first operational amplifier outputs a signal which is the difference between the current common voltage signal and the reference common voltage signal; The relationship between the resistance accuracy ΔR, the maximum error of the data voltage and the common voltage value meets the following formula requirements: Wherein, ΔVsource error is the maximum error of the data voltage, m=(1+ΔR) / (1-ΔR), Vcom′ is the common voltage reference value, and Vcom is the current common voltage value.

7. The pixel voltage compensation method according to claim 6, wherein: Before monitoring the fluctuation of the common voltage in real time by the voltage difference acquisition circuit, the method further includes: When it is determined that the current period is the display period, the voltage difference acquisition circuit is used to monitor the fluctuation of the common voltage in real time.

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