A VCOM signal generation circuit, method and display panel

Abstract

Embodiments of the present application provide a VCOM signal generation circuit, method, and display panel. By receiving the CLK signal of the gate driving circuit of the display panel, a VCOM compensation reference voltage is generated based on the duty cycle of the CLK signal, and a VCOM compensation signal is generated based on the VCOM compensation reference voltage. In this way, during the display stage, the number of pixel rows of the TX block can be scanned based on the gate signal, and the VCOM signal of the common electrode of the TX block is determined from the VCOM compensation signal and the DC VCOM voltage signal. In this way, corresponding VCOM compensation signals can be generated for different duty cycles, and adaptive adjustment is performed based on the VCOM compensation signals, thereby reducing the horizontal stripe phenomenon at the TX junction and ensuring a good final display effect.

Description

Technical Field

[0001] The present application relates to the field of display technologies, and particularly to a VCOM signal generation circuit, method, and display panel. Background Art

[0002] A display panel includes an active display area (AA area), where the AA area includes a plurality of TX (Transport, transmit) blocks arranged in an array. For each TX block, the TX block includes a plurality of scan lines (gate lines).

[0003] Gate Driver on array (GOA) of a display panel is a technology that uses the original process of the flat display panel to fabricate the driving circuit of the panel's horizontal scan lines on the panel around the display area. The GOA circuit has a positive-phase clock signal input terminal CLK, an inverted-phase clock signal input terminal CLKB, and a low-voltage signal input terminal VSS. The GOA circuit outputs a gate signal to scan the scan lines (gate lines) in the TX block.

[0004] Currently, the touch and display functions of a smart phone are independently controlled by two chips. For a display product with Touch and Display Driver Integration (TDDI), the biggest feature is integrating the touch chip and the display chip into a single chip, achieving a thinner form factor, brighter display, and a narrow-bezel panel design.

[0005] TDDI provides a VCOM signal in the display stage driving module (Integrated Circuit), and provides a touch signal in the touch stage driving module.

[0006] Among them, when TDDI is in the touch stage, the driving signal of the TX block instantaneously jumps from the VCOM signal to the touch signal, causing a relatively large coupling capacitance, resulting in a difference in VCOM between the edge and the center of the TX block. The difference in VCOM between the edge and the center of the TX block causes "horizontal lines at the edge of the TX square" to appear in the display screen, thereby causing abnormal display. Summary of the Invention

[0007] The purpose of the embodiments of the present application is to provide a VCOM signal generation circuit, method, and display panel to reduce the phenomenon of horizontal stripes at the TX junction and ensure a good final display effect. The specific technical solutions are as follows:

[0008] The embodiments of the present application provide a VCOM signal generation circuit, including:

[0009] An input module, a PWM control module, and a selection module;

[0010] The input module is configured to receive the CLK signal of the gate driving circuit of the display panel;

[0011] The PWM control module is configured to generate a VCOM compensation reference voltage based on the duty cycle of the CLK signal, and generate a VCOM compensation signal based on the VCOM compensation reference voltage;

[0012] The selection module is configured to receive the DC VCOM voltage signal corresponding to the TX block. During the display stage, based on the number of pixel rows currently scanned by the gate signal in the TX block, select one signal from the VCOM compensation signal and the DC VCOM voltage signal as the VCOM signal for the common electrode of the TX block; wherein, for each TX block, the TX block includes multiple pixel rows, and for each pixel row, the pixel row corresponds to a common electrode.

[0013] In a possible implementation manner, the selection module is specifically configured to:

[0014] When the gate signal refreshes to a preset number of pixel rows before or after the TX block, use the VCOM compensation signal as the VCOM signal for the common electrode of the TX block.

[0015] In a possible implementation manner, the selection module is specifically configured to:

[0016] When the gate signal refreshes to the middle row of the TX block, use the DC VCOM voltage signal as the VCOM signal of the TX block, where the middle row of the TX block is other pixel rows outside the preset number of pixel rows before and after the TX block.

[0017] In a possible implementation manner, the selection module is specifically configured to:

[0018] During the touch stage, obtain the Touch square wave voltage signal, and use the Touch square wave voltage signal as the VCOM signal for the common electrode of the TX block.

[0019] An embodiment of the present application further provides a method for generating a VCOM signal, the method including:

[0020] Obtain the CLK signal of the gate driving circuit of the display panel;

[0021] Generate a VCOM compensation reference voltage based on the duty cycle of the CLK signal, and generate a VCOM compensation signal based on the VCOM compensation reference voltage;

[0022] Receive the DC VCOM voltage signal corresponding to the TX block. During the display stage, based on the number of rows of pixels in the TX block currently scanned by the gate signal, select one signal from the VCOM compensation signal and the DC VCOM voltage signal as the VCOM signal for the common electrode of the TX block; wherein, for each TX block, the TX block includes multiple pixel rows, and for each pixel row, the pixel row corresponds to a common electrode.

[0023] In a possible implementation manner, during the display stage, based on the number of rows of pixels in the TX block scanned by the gate signal, select one signal from the VCOM compensation signal and the DC VCOM voltage signal as the VCOM signal for the common electrode of the TX block, including:

[0024] When the gate signal refreshes to a preset number of pixel rows before or after the TX block, use the VCOM compensation signal as the VCOM signal for the common electrode of the TX block.

[0025] In a possible implementation manner, during the display stage, based on the number of rows of pixels in the TX block scanned by the gate signal, select one signal from the VCOM compensation signal and the DC VCOM voltage signal as the VCOM signal for the common electrode of the TX block, including:

[0026] When the gate signal refreshes to the middle row of the TX block, use the DC VCOM voltage signal as the VCOM signal for the common electrode of the TX block, where the middle row of the TX block is other pixel rows outside the preset number of pixel rows before and after the TX block.

[0027] In a possible implementation manner, the method further includes:

[0028] During the touch stage, obtain the Touch square wave voltage signal and use the Touch square wave voltage signal as the VCOM signal for the common electrode of the TX block.

[0029] An embodiment of the present application provides a display panel, including the VCOM signal generation circuit described in any one of the above.

[0030] Beneficial effects of the embodiments of the present application:

[0031] A VCOM signal generation circuit, method and display panel provided by an embodiment of the present application receive a CLK signal of a gate driving circuit of the display panel, generate a VCOM compensation reference voltage based on the duty cycle of the CLK signal, and generate a VCOM compensation signal based on the VCOM compensation reference voltage. In this way, during the display stage, the number of pixel rows of the TX block can be scanned based on the gate signal, and the VCOM signal of the common electrode of the TX block can be determined from the VCOM compensation signal and the DC VCOM voltage signal. In this way, corresponding VCOM compensation signals can be generated for different duty cycles, and adaptive adjustment can be performed based on the VCOM compensation signals, so as to reduce the crosshatch phenomenon at the TX junction and ensure good final display effects.

[0032] Of course, it is not necessary for any product or method implementing the present application to achieve all the above advantages simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other embodiments can also be obtained based on these drawings.

[0034] Figure 1 It is a timing diagram of GOA in the related art;

[0035] Figure 2 It is a schematic diagram of the VCOM waveform at the junction of TX blocks in the related art;

[0036] Figure 3 It is a schematic structural diagram of a VCOM signal generation circuit provided by an embodiment of the present application;

[0037] Figure 4 It is a schematic flowchart of the operation of the VCOM signal generation circuit provided by an embodiment of the present application;

[0038] Figure 5 It is a schematic flowchart of a VCOM signal generation method provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art based on the present application belong to the scope of protection of the present application.

[0040] The TDDI product divides the common electrode (VCOM) of the pixel unit into blocks, which are used as the TX blocks for touch detection. At the center and edges of the TX blocks, due to the difference in the coupling situation of the gate lines, horizontal stripes are likely to occur at the TX junctions visually.

[0041] The specific principle of the occurrence of horizontal stripes at the TX junctions visually is as follows: Assume that there are n rows of gate lines in a single TX block, where Gi is the i-th row of gate lines, i ∈ {1, …, n}, and the 8-phase GOA timing in this TX block is as Figure 1 shown. Figure 1 It is a schematic diagram of the GOA timing in the related art.

[0042] Among them, Gsum is the sum of the simultaneously turned-on gate lines; the degree to which the TX block is pulled is proportional to Gsum; as Figure 2 shown. Figure 2 It is a schematic diagram of the VCOM waveform at the TX block junction in the related art. The IC (Integrated Circuit) outputs a stable VCOM. However, due to the coupling situation of the gate lines in the display panel, the coupled VCOM in the display panel is pulled slightly less at the TX block junction, and the VCOM amplitude is low. Correspondingly, the VCOM amplitude at the center of the TX block is high. Therefore, the difference in VCOM between the edge and the center of the TX block will cause "horizontal lines at the edge of the TX square" to appear in the display picture.

[0043] Therefore, this application provides a VCOM signal generation circuit. Refer to Figure 3 , Figure 3 which is a schematic structural diagram of a VCOM signal generation circuit provided by an embodiment of this application, including:

[0044] An input module, a PWM control module, and a selection module;

[0045] The above input module is used to receive the CLK signal of the gate driving circuit of the display panel;

[0046] The above PWM control module is used to generate a VCOM compensation reference voltage based on the duty cycle of the above CLK signal, and generate a VCOM compensation signal based on the above VCOM compensation reference voltage;

[0047] The above selection module is used to receive the DC VCOM voltage signal corresponding to the TX block. During the display stage, based on the number of rows of the pixel rows currently scanned by the gate signal in the TX block, it selects one signal from the above VCOM compensation signal and the DC VCOM voltage signal as the VCOM signal of the common electrode of the TX block; among them, for each TX block, the TX block includes multiple pixel rows, and for each pixel row, the pixel row corresponds to a common electrode.

[0048] The PWM control module is electrically connected to the input module and the selection module respectively.

[0049] The display panel can be a liquid crystal display panel, which includes multiple gate lines extending in the row direction and multiple data lines extending in the column direction. The area enclosed by the intersection of the gate lines and the data lines defines pixel units. Each pixel unit has an independent pixel electrode, and each pixel electrode is independently loaded with a data voltage for independent display. In addition, the liquid crystal display panel also includes a common electrode shared by all pixel units, which is loaded with a unified common voltage. In each pixel unit, the voltage difference between the common electrode and the corresponding pixel electrode is called the "display voltage" of the pixel unit. The display voltage can drive the liquid crystal molecules in the corresponding pixel unit to deflect, so that the pixel unit displays the required brightness.

[0050] The display panel includes an active display area (AA area), where the active display area includes multiple TX blocks. For each TX block, the TX block includes multiple pixel rows, and for each pixel row, the pixel row shares a gate line. For each TX block, it is necessary to obtain the CLK signal of the GOA circuit of the display panel. The input module sends the received CLK signal to the PWM control module, and then the PWM control module generates a VCOM compensation reference voltage based on the duty cycle of the CLK signal. Under different CLK duty cycles, the DC voltage generated by the PWM control module will change. The higher the CLK duty cycle, the higher the PWM output voltage. Because the generated VCOM compensation reference voltage is a DC voltage, and as Figure 2 shown, the coupled VCOM voltage at the junction of the TX blocks is actually a triangular wave voltage. Therefore, a triangular wave voltage can be generated based on the VCOM compensation reference voltage. The generated triangular wave voltage is determined based on the magnitude of the coupled VCOM voltage in the display panel. After the generated triangular wave voltage is coupled, a stable DC voltage can be obtained.

[0051] And send the VCOM compensation signal to the selection module. Among them, the PWM control module can be any PWM control circuit.

[0052] The selection module obtains the DC VCOM voltage signal corresponding to the TX block. During the display stage, based on the gate signal, it scans the number of rows of the pixel rows of the TX block, and selects the corresponding signal from the VCOM compensation signal and the DC VCOM voltage signal as the VCOM signal of the common electrode of the TX block, so that the pixel unit displays the required brightness.

[0053] By receiving the CLK signal of the gate driving circuit of the display panel, generating a VCOM compensation reference voltage based on the duty cycle of the CLK signal, and generating a VCOM compensation signal based on the VCOM compensation reference voltage, during the display stage, the number of pixel rows of the TX block can be scanned based on the gate signal, and the VCOM signal of the common electrode of the TX block can be determined from the VCOM compensation signal and the DC VCOM voltage signal. In this way, corresponding VCOM compensation signals can be generated for different duty cycles, and adaptive adjustment can be performed based on the VCOM compensation signals, thereby reducing the horizontal stripe phenomenon at the TX junction and ensuring a good final display effect.

[0054] In a possible implementation manner, the above selection module is specifically configured to:

[0055] When the gate signal refreshes to a preset number of pixel rows before or after the TX block, use the above VCOM compensation signal as the VCOM signal of the common electrode of the TX block.

[0056] The preset number of pixel rows before or after the TX block are the pixel rows at the junction of the TX block and other TX blocks. The preset number is set based on the actual situation. The preset number of rows are the pixel rows where the horizontal stripe phenomenon occurs and the voltage of their common electrodes needs to be compensated. Exemplarily, as Figure 1 shown, the preset number can be set to 4.

[0057] When the gate signal refreshes to 4 pixel rows before or 4 pixel rows after the TX block, since the VCOM compensation signal is generated based on the CLK signal of the gate driving circuit of the display panel, the VCOM compensation signal can be used as the VCOM signal of the common electrode of the TX block. In this way, the compensated VCOM output by the IC (Integrated Circuit) is higher at the TX junction than at the center of the TX block. After internal gate coupling, the VCOM actually loaded onto the pixels can tend to be stable, reducing the horizontal stripe phenomenon at the TX junction.

[0058] Under normal circumstances, the higher the duty cycle, the greater the overlap between the gate lines, the more severely the VCOM is coupled by the gate lines, and the more obvious the horizontal stripes. In this application, the higher the duty cycle, the greater the compensation amplitude of the generated VCOM compensation signal. Adaptive adjustment can be performed for different duty cycles to reduce the horizontal stripe phenomenon at the TX junction and ensure a good final display effect.

[0059] In a possible implementation manner, the above selection module is specifically configured to:

[0060] When the gate signal is refreshed to the middle row of the TX block, the above DC VCOM voltage signal is used as the VCOM signal of the common electrode of the TX block, where the middle row of the TX block is other pixel rows except for a preset number of pixel rows in front of the TX block and a preset number of pixel rows behind the TX block.

[0061] When the gate signal is refreshed to the middle row of the TX block, the DC VCOM voltage signal is directly used as the VCOM signal of the common electrode of the TX block, so that the pixel unit displays the required brightness.

[0062] In a possible implementation manner, the above selection module is specifically configured to:

[0063] In the touch stage, obtain the Touch square wave voltage signal, and use the Touch square wave voltage signal as the VCOM signal of the common electrode of the TX block.

[0064] In the touch stage, the selection module can obtain the Touch square wave voltage signal and directly use the Touch square wave voltage signal as the VCOM signal of the common electrode of the TX block to implement touch within its area range.

[0065] Based on the above embodiments, the embodiments of the present application provide a schematic flow diagram of the operation of the VCOM signal generation circuit, specifically refer to Figure 4 ;

[0066] The selection module uses a MUX (Multiplexer, data selector) time-sharing selector. Exemplarily, the MUX time-sharing selector is a three-to-one time-sharing selector.

[0067] The input module receives the CLK signal of the gate driving circuit of the display panel;

[0068] The PWM control module generates a VCOM compensation reference voltage based on the duty cycle of the CLK signal, and generates a VCOM compensation signal based on the VCOM compensation reference voltage.

[0069] The MUX time-division selector acquires the VCOM compensation signal, the DC VCOM signal, and the Touch square wave signal; the MUX time-division selector outputs the corresponding VCOM signal based on different working phases. Specifically, in the display phase, when the gate signal refreshes to a preset number of pixel rows before or after the TX block, the VCOM compensation signal is used as the VCOM signal of the common electrode of the TX block. When the gate signal refreshes to the middle row of the TX block, the DC VCOM voltage signal is used as the VCOM signal of the common electrode of the TX block, where the middle row of the TX block is other pixel rows outside the preset number of pixel rows before and after the TX block. In the touch phase, the Touch square wave voltage signal is acquired and used as the VCOM signal of the common electrode of the TX block.

[0070] Based on the above embodiments, refer to Figure 5 , Figure 5 which is a schematic flowchart of a method for generating a VCOM signal provided by an embodiment of the present application. The method includes:

[0071] S510, acquire the CLK signal of the gate driving circuit of the display panel;

[0072] S520, generate a VCOM compensation reference voltage based on the duty cycle of the above CLK signal, and generate a VCOM compensation signal based on the above VCOM compensation reference voltage;

[0073] S530, receive the DC VCOM voltage signal corresponding to the TX block. In the display phase, based on the number of rows of the pixel rows of the TX block currently scanned by the gate signal, select one signal from the above VCOM compensation signal and the above DC VCOM voltage signal as the VCOM signal of the common electrode of the TX block; wherein, for each TX block, the TX block includes multiple pixel rows, and for each pixel row, the pixel row corresponds to a common electrode.

[0074] In a possible implementation manner, the above-mentioned in the display phase, based on the number of rows of the pixel rows of the TX block scanned by the gate signal, select one signal from the above VCOM compensation signal and the above DC VCOM voltage signal as the VCOM signal of the common electrode of the TX block, includes:

[0075] When the gate signal refreshes to a preset number of pixel rows before or after the TX block, use the above VCOM compensation signal as the VCOM signal of the common electrode of the TX block.

[0076] In a possible implementation manner, during the display stage, based on the number of rows of pixels in the TX block scanned by the gate signal, one signal is selected from the VCOM compensation signal and the DC VCOM voltage signal as the VCOM signal for the common electrode of the TX block, including:

[0077] When the gate signal refreshes to the middle row of the TX block, the DC VCOM voltage signal is used as the VCOM signal for the common electrode of the TX block, where the middle row of the TX block is the other pixel rows except for the preset number of pixel rows in front of the TX block and the preset number of pixel rows behind the TX block.

[0078] In a possible implementation manner, the above method further includes:

[0079] During the touch stage, obtain the Touch square wave voltage signal, and use the Touch square wave voltage signal as the VCOM signal for the common electrode of the TX block.

[0080] The embodiment of the present application provides a display panel, including the above-mentioned VCOM signal generation circuit.

[0081] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the element.

[0082] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the method embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the related parts can be referred to the partial description of the method embodiments.

[0083] The above are only the preferred embodiments of the present application, and are not used to limit the protection scope of the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application are all included in the protection scope of the present application.

Claims

1. A VCOM signal generation circuit, characterized in that, including: an input module, a PWM control module, and a selection module; the input module is configured to receive a CLK signal of a gate driving circuit of a display panel; the PWM control module is configured to generate a VCOM compensation reference voltage based on a duty cycle of the CLK signal, and generate a VCOM compensation signal based on the VCOM compensation reference voltage; the selection module is configured to receive a DC VCOM voltage signal corresponding to a TX block, and in a display stage, select one signal from the VCOM compensation signal and the DC VCOM voltage signal as a VCOM signal of a common electrode of the TX block based on a row number of a pixel row of the TX block currently scanned by a gate signal; wherein, for each TX block, the TX block includes a plurality of pixel rows, and for each pixel row, the pixel row corresponds to a common electrode.

2. The circuit according to claim 1, wherein Specifically, the selection module is configured to: when the gate signal refreshes to a preset number of pixel rows before or after the TX block, use the VCOM compensation signal as the VCOM signal of the common electrode of the TX block.

3. The circuit according to claim 1, wherein Specifically, the selection module is configured to: when the gate signal refreshes to a middle row of the TX block, use the DC VCOM voltage signal as the VCOM signal of the common electrode of the TX block, where the middle row of the TX block is other pixel rows except for a preset number of pixel rows before and after the TX block.

4. The circuit according to claim 1, characterized in that, Specifically, the selection module is configured to: in a touch stage, obtain a Touch square wave voltage signal, and use the Touch square wave voltage signal as the VCOM signal of the common electrode of the TX block.

5. The circuit according to claim 4, characterized in that, The selection module is a three-to-one time-division selector.

6. A method for generating a VCOM signal, characterized in that, The method includes: obtaining a CLK signal of a gate driving circuit of a display panel; generating a VCOM compensation reference voltage based on a duty cycle of the CLK signal, and generating a VCOM compensation signal based on the VCOM compensation reference voltage; receiving a DC VCOM voltage signal corresponding to a TX block, and in a display stage, selecting one signal from the VCOM compensation signal and the DC VCOM voltage signal as a VCOM signal of a common electrode of the TX block based on a row number of a pixel row of the TX block currently scanned by a gate signal; wherein, for each TX block, the TX block includes a plurality of pixel rows, and for each pixel row, the pixel row corresponds to a common electrode.

7. The method according to claim 6, characterized in that, The step of, in the display stage, selecting one signal from the VCOM compensation signal and the DC VCOM voltage signal as a VCOM signal of a common electrode of the TX block based on a row number of a pixel row of the TX block scanned by a gate signal includes: when the gate signal refreshes to a preset number of pixel rows before or after the TX block, using the VCOM compensation signal as the VCOM signal of the common electrode of the TX block.

8. The method according to claim 6, characterized in that, The step of, in the display stage, selecting one signal from the VCOM compensation signal and the DC VCOM voltage signal as a VCOM signal of a common electrode of the TX block based on a row number of a pixel row of the TX block scanned by a gate signal includes: When the gate signal is refreshed to the middle row of the TX block, the DC VCOM voltage signal is used as the VCOM signal of the common electrode of the TX block, where the middle row of the TX block is other pixel rows except for a preset number of pixel rows in front of the TX block and a preset number of pixel rows behind the TX block.

9. The method according to claim 6, wherein The method further includes: In the touch stage, a Touch square wave voltage signal is acquired, and the Touch square wave voltage signal is used as the VCOM signal of the common electrode of the TX block.

10. A display panel, characterized in that, It includes the VCOM signal generation circuit according to any one of claims 1 to 5.

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