Tft substrate, electronic paper display device, and pixel driving method

Abstract

The application discloses a TFT substrate, an electronic paper display device and a pixel driving method. The TFT substrate comprises a substrate, a thin film transistor layer which is arranged in layers on the substrate and comprises a first TFT device and a second TFT device corresponding to each pixel unit, a source of the first TFT device is used for receiving a pixel driving signal, a drain of the first TFT device is connected with a source of the second TFT device, a gate of the first TFT device and a gate of the second TFT device are respectively used for receiving respective gate driving signals, and a pixel electrode layer which is arranged in layers on the thin film transistor layer and comprises a first pixel electrode and a second pixel electrode arranged at intervals, the first pixel electrode is located above the first TFT device and the second TFT device and is connected with the drain of the first TFT device, and the second pixel electrode is connected with the drain of the second TFT device.

Description

Technical Field

[0001] This invention relates to the field of display technology, and in particular to a TFT substrate, an electronic paper display device, and a pixel driving method. Background Technology

[0002] Electronic paper, characterized by its thinness, flexibility, and energy efficiency, is widely used in portable products and products with lower dynamic display requirements, such as billboards, notice boards, labels, watches, mobile phones, e-paper readers, and flexible displays. However, with the widespread application of electronic paper, the demands on its display quality are also increasing. Targeted elimination of display defects has become a crucial way to improve product quality. For example, some current electronic paper products are prone to display defects such as ghosting, black lines on red screens, and red lines on black screens due to color shifts. Summary of the Invention

[0003] In view of the above problems, the present invention is proposed to provide a TFT substrate, an electronic paper display device, and a pixel driving method that overcome or at least partially solve the above problems.

[0004] In a first aspect, embodiments of this specification provide a TFT substrate, comprising:

[0005] Substrate;

[0006] A thin-film transistor layer, stacked on the substrate, includes a first TFT device and a second TFT device corresponding to each pixel unit. The source of the first TFT device is used to receive a pixel driving signal, the drain of the first TFT device is connected to the source of the second TFT device, and the gates of the first TFT device and the second TFT device are respectively used to receive their respective gate driving signals.

[0007] A pixel electrode layer is stacked on the thin film transistor layer and includes a first pixel electrode and a second pixel electrode spaced apart. The first pixel electrode is located on the first TFT device and the second TFT device and is connected to the drain of the first TFT device. The second pixel electrode is connected to the drain of the second TFT device.

[0008] Furthermore, the orthographic projections of the first TFT device and the second TFT device onto the substrate constitute a first projection region, and the orthographic projection of the first pixel electrode onto the substrate constitutes a second projection region, wherein the first projection region and the second projection region at least partially overlap.

[0009] Furthermore, the orthographic projection of the channel region of the first TFT device on the substrate at least partially overlaps with the second projection region, and the orthographic projection of the channel region of the second TFT device on the substrate does not overlap with the second projection region; the orthographic projection of the second pixel electrode on the substrate is a third projection region, and the orthographic projection of the channel region of the second TFT device on the substrate does not overlap with the third projection region.

[0010] Furthermore, the orthogonal projection of the gate of the first TFT device on the substrate at least partially overlaps with the second projection region, and the orthogonal projection of the gate of the second TFT device on the substrate does not overlap with the second projection region; the orthogonal projection of the second pixel electrode on the substrate is a third projection region, and the orthogonal projection of the gate of the second TFT device on the substrate does not overlap with the third projection region.

[0011] Furthermore, the sum of the areas of the first pixel electrode and the second pixel electrode accounts for more than or equal to 76% of the area of ​​the pixel unit.

[0012] Furthermore, the thin-film transistor layer further includes: a first storage capacitor electrode and a second storage capacitor electrode, wherein the first storage capacitor electrode is disposed opposite to the first pixel electrode to form a first storage capacitor, and the second storage capacitor electrode is disposed opposite to the second pixel electrode to form a second storage capacitor.

[0013] Furthermore, the TFT substrate further includes: a protective layer disposed between the thin film transistor layer and the pixel electrode layer, wherein a first via and a second via are disposed on the protective layer;

[0014] The thin-film transistor layer includes: a gate metal layer, a gate insulating layer, an active layer, and a source / drain metal layer sequentially stacked on the substrate, wherein the source / drain metal layer includes a first drain layer serving as the drain of the first TFT device and a second drain layer serving as the drain of the second TFT device.

[0015] The first pixel electrode is connected to the first drain layer through the first via, and the second pixel electrode is connected to the second drain layer through the second via.

[0016] Furthermore, the first via is located between the first TFT device and the second TFT device, and the diameter of the first via is smaller than the diameter of the second via.

[0017] Furthermore, the TFT substrate further includes: a first gate driving circuit and a second gate driving circuit;

[0018] The output terminal of the first gate driving circuit is connected to the gate of the first TFT device to provide a first gate driving signal to the gate of the first TFT device.

[0019] The output of the second gate driving circuit is connected to the gate of the second TFT device, providing a second gate driving signal to the gate of the second TFT device.

[0020] Secondly, embodiments of this specification also provide an electronic paper display device, including: the TFT substrate described in the first aspect above.

[0021] Thirdly, embodiments of this application provide a pixel driving method applied to the electronic paper display device provided in the second aspect above, the method comprising:

[0022] Receive the pixel driving signal corresponding to the current frame image. The pixel driving signal includes: a main driving signal segment and a compensation driving signal segment.

[0023] During the refresh phase, both the first TFT device and the second TFT device are turned on, and the first pixel electrode and the second pixel electrode are driven by the main driving signal segment to refresh the sub-pixel corresponding to the first pixel electrode and the sub-pixel corresponding to the second pixel electrode.

[0024] During the compensation phase, the first TFT device is turned on and the second TFT device is turned off. The first pixel electrode is driven by the compensation drive signal segment to compensate and refresh the sub-pixel corresponding to the first pixel electrode.

[0025] Furthermore, both the refresh stage and the compensation stage include: a color inversion stage, a dithering stage, and a color rendering stage.

[0026] Furthermore, the waveform of the compensation drive signal segment is determined by comparing the color changes of each pixel corresponding to the current frame image with those of the previous frame image.

[0027] The technical solutions provided in the embodiments of this specification have at least the following technical effects or advantages:

[0028] The TFT substrate, electronic paper display device, and pixel driving method provided in the embodiments of this specification achieve electric field compensation for sub-pixels at the TFT switch by adding a first pixel electrode above the TFT device of each pixel unit. The first pixel electrode is spaced apart from the original second pixel electrode and connected to the second electrode of the first TFT device. This effectively improves the display defects caused by color shift due to the weak electric field strength above the TFT device, such as poor ghosting test, black lines on red screen, and red lines on black screen, which is beneficial to optimizing the display effect.

[0029] Furthermore, since the first pixel electrode and the second pixel electrode are spaced apart from each other, meaning that the voltages of the first pixel electrode and the second pixel electrode can be controlled independently, in addition to uniformly refreshing the first pixel electrode and the second pixel electrode during the pixel driving process, a compensation refresh of the sub-pixel corresponding to the first pixel electrode can be added to ensure the refresh reliability of the TFT device area and further improve the display defects caused by color shift in the TFT device area.

[0030] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0031] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0032] Figure 1 The image shows a defective red TFT area when the electronic paper displays a black screen;

[0033] Figure 2 This specification shows a schematic diagram of the structure of a pixel unit on a TFT substrate in an embodiment of the present specification;

[0034] Figure 3 A cross-sectional schematic diagram of the TFT substrate in an embodiment of this specification is shown;

[0035] Figure 4 A schematic diagram of the electronic paper display device in the embodiments of this specification is shown;

[0036] Figure 5 A flowchart of the pixel driving method in an embodiment of this specification is shown;

[0037] Figure 6 An equivalent circuit diagram of the pixel driving circuit in the embodiments of this specification is shown;

[0038] Figure 7 A schematic diagram of the pixel driving signal in an embodiment of this specification is shown. Detailed Implementation

[0039] In traditional electronic paper, the area above the TFT (Thin Film Transistor) of a pixel is not covered by a pixel electrode. As a result, the electric field in this area is weaker, leading to a color shift compared to areas covered by pixel electrodes. This has caused numerous defects in actual products, such as poor Ghosting test results, red screen with black lines, and black screen with red lines.

[0040] Electronic paper displays use an electric field to drive charged colored particles to display images. The image quality, such as color and brightness, is affected by the electric field. Therefore, even small differences in the electric field can cause the movement and distribution of charged particles, resulting in defects. For example, display testing can be performed before product packaging to check for defects when the electronic paper displays different colors. Figure 1 When a black screen is displayed, a red, faulty image appears at the TFT position. For example... Figure 1 As shown, the black area is the AA (effective display) area, and the honeycomb film layer is the electronic paper film, i.e., the display layer. When the electronic paper displays a black image, the bright spots circled in white are red defective points, which are distributed at the TFT positions. It should be noted that, due to... Figure 1 Since it is a grayscale image, defects are not very obvious.

[0041] Based on this, the embodiments of this specification propose a TFT substrate, an electronic paper display device, and a pixel driving method. By adding a first pixel electrode above the TFT device of each pixel unit, the first pixel electrode is spaced apart from the original second pixel electrode and connected to the second electrode of the first TFT device. In this way, by applying electricity to the first pixel electrode, electric field compensation of the sub-pixel at the TFT switch can be achieved. This helps to improve display defects caused by weak electric field strength above the TFT device, such as poor Ghosting test, red screen with black lines, and black screen with red lines, so as to achieve a better display effect.

[0042] Exemplary embodiments of the TFT substrate, electronic paper display device, and pixel driving method provided in this disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that the dimensions of layers and regions may be exaggerated in the drawings for clarity. While exemplary embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this disclosure and to fully convey the scope of this disclosure to those skilled in the art. The term "plural" as used herein includes two or more cases.

[0043] In a first aspect, embodiments of this specification provide a TFT substrate, which includes a substrate 100 and a plurality of pixel units arranged in an array on the substrate 100. For example... Figure 2As shown, each pixel unit includes a TFT device region 101 and a pixel region 102, wherein the TFT device region 101 is provided with a first TFT device T1 and a second TFT device T2.

[0044] like Figure 3 As shown, the TFT substrate may include: a substrate 100, a thin film transistor layer 110, and a pixel electrode layer 130. For example, the substrate 100 may be made of a suitable rigid substrate material such as glass or silicon, or it may be made of a flexible substrate material such as PI (polyimide). The specific material can be determined according to actual needs, and this embodiment does not limit it.

[0045] A thin-film transistor layer 110 is stacked on the substrate 100. The thin-film transistor layer 110 includes a first TFT device T1 and a second TFT device T2 for each pixel unit. The source of the first TFT device T1 is used to receive a pixel driving signal. The drain of the first TFT device T1 is connected to the source of the second TFT device T2. The gate of the first TFT device T1 and the gate of the second TFT device T2 are respectively used to receive their respective gate driving signals.

[0046] A pixel electrode layer 130 is stacked on the thin-film transistor layer 110. The pixel electrode layer 130 includes a first pixel electrode 131 and a second pixel electrode 132 for each pixel unit. The first pixel electrode 131 and the second pixel electrode 132 are spaced apart and insulated from each other. The specific spacing can be determined according to actual process requirements and crosstalk conditions. The first pixel electrode 131 is located above the first TFT device T1 and the second TFT device T2, i.e., in the TFT device region 101, and is connected to the drain of the first TFT device T1. The second pixel electrode 132 is connected to the drain of the second TFT device T2. For example, the first pixel electrode 131 and the second pixel electrode 132 can be disposed in the same layer, and the electrode material can be indium tin oxide (ITO).

[0047] It should be noted that the coverage area of ​​the first pixel electrode 131 over the TFT region can be determined according to the needs of the actual scenario. For example, the orthographic projection of the first TFT device T1 and the second TFT device T2 onto the substrate 100 is the first projection region. The orthographic projection of the first pixel electrode 131 onto the substrate 100 is the second projection region, and the first projection region may at least partially overlap with the second projection region. In some examples, the second projection region does not overlap with the orthographic projection of the channel region of the first TFT device T1 onto the substrate 100, nor with the orthographic projection of the channel region of the second TFT device T2 onto the substrate 100, to ensure the performance of the channel regions of the two TFT devices. Furthermore, the second projection region also does not overlap with the orthographic projection of the gate of the first TFT device T1 onto the substrate 100, nor with the orthographic projection of the gate of the second TFT device T2 onto the substrate 100, to further ensure the switching performance of the two TFT devices.

[0048] In some examples, to improve the pixel aperture ratio, without affecting the display, the second projection area may at least partially overlap with the orthogonal projection of the channel region of the first TFT device T1 onto the substrate 100. Furthermore, the second projection area may also at least partially overlap with the orthogonal projection of the gate of the first TFT device T1 onto the substrate 100. Of course, the second projection area still does not overlap with the orthogonal projections of the channel region and gate of the second TFT device T2 onto the substrate 100, to ensure the switching performance of the second TFT device T2. In other words, if it does not affect the display, the first pixel electrode 131 can be made as large as possible; this embodiment does not impose such limitations.

[0049] The second pixel electrode 132 can be disposed in other areas of the same pixel unit besides the TFT device region 101, namely the aforementioned pixel region 102. The specific coverage area of ​​the pixel region 102 can be found in related technologies and will not be detailed here. For example, the orthogonal projection of the second pixel electrode 132 onto the substrate 100 is the third projection region, and the orthogonal projection of the channel region of the second TFT device T2 onto the substrate 100 does not overlap with the third projection region. Furthermore, the orthogonal projection of the gate of the second TFT device T2 onto the substrate 100 also does not overlap with the third projection region, thus ensuring the switching performance of the second TFT device T2.

[0050] In some examples, the sum of the areas of the first pixel electrode 131 and the second pixel electrode 132 accounts for more than or equal to 76% of the area of ​​the pixel unit. Here, the area of ​​the pixel unit refers to the area of ​​the pixel region defined by the gate lines and data lines. For example, if the first pixel electrode 131 completely covers the first TFT device T1, the aforementioned area ratio can be increased to 87%, meaning the pixel aperture ratio can be increased to 87%.

[0051] By adding a first pixel electrode 131 to the TFT device region 101, electric field compensation can be performed on the sub-pixels corresponding to the TFT device region 101 by applying power to the first pixel electrode 131. This improves the display defects caused by the weaker electric field intensity of the TFT device region 101 relative to the pixel region 102 during electronic paper display, such as poor Ghosting test, red screen with black lines, black screen with red lines, etc., which is beneficial to optimizing the display effect of electronic paper.

[0052] Furthermore, since the first pixel electrode 131 and the second pixel electrode 132 are arranged at intervals, that is, within the same pixel unit, the voltage of the first pixel electrode 131 and the voltage of the second pixel electrode 132 can be controlled independently. In this way, in the pixel driving process, in addition to uniformly refreshing the first pixel electrode 131 and the second pixel electrode 132, a compensation refresh of the sub-pixel corresponding to the first pixel electrode 131 can be added to ensure the refresh reliability of the sub-pixels of the TFT device area 101, and further improve the display defects caused by the color shift of the TFT device area 101.

[0053] For example, the pixel driving process of the same pixel unit can be divided into a unified refresh stage and a compensation stage, and the pixel driving waveform can be divided into a main driving waveform and a compensation driving waveform. In the unified refresh stage, both the first TFT device T1 and the second TFT device T2 are turned on, and the first pixel electrode 131 and the second pixel electrode 132 are driven by the main driving waveform to refresh the display screen of the sub-pixels corresponding to the first pixel electrode 131 and the second pixel electrode 132. In the compensation stage, the first TFT device T1 is turned on and the second TFT device T2 is turned off to perform compensation refresh on the sub-pixels corresponding to the first pixel electrode 131. The specific process will be described in detail in the method embodiments below.

[0054] It should be noted that, in order to achieve compensated driving of the first pixel electrode 131, the first TFT device T1 and the second TFT device T2 need to be switched independently, that is, the first TFT device T1 and the second TFT device T2 need to be switched independently. Therefore, a gate driving circuit needs to be added to provide independent gate driving signals for the first TFT device T1 and the second TFT device T2.

[0055] In some examples, the gate driving circuit can be integrated on the TFT substrate, for example, a GOA (Gate Driver On Array) circuit can be used. In this case, the TFT substrate also includes a first gate driving circuit and a second gate driving circuit (not shown in the figure). The output of the first gate driving circuit is connected to the gate of the first TFT device T1, providing a first gate driving signal to the gate of the first TFT device T1; the output of the second gate driving circuit is connected to the gate of the second TFT device T2, providing a second gate driving signal to the gate of the second TFT device T2. Thus, by configuring the waveforms of the first and second gate driving signals, the first TFT device T1 and the second TFT device T2 can be switched on and off respectively.

[0056] It should be noted that in other examples, the gate driving circuit may not be disposed on the TFT substrate, and this embodiment does not impose any restrictions on this.

[0057] Because the structures of each pixel unit are similar Figure 3 The image shown is a screenshot of a pixel unit in a TFT substrate. Figure 3 As shown, the thin-film transistor layer 110 may include a gate metal layer 111, a gate insulating layer 112, an active layer, and a source / drain metal layer 113 sequentially stacked on the substrate 100. The patterned gate metal layer 111 includes a first gate layer 1111 and a second gate layer 1112.

[0058] In addition, the thin-film transistor layer 110 further includes a first storage capacitor electrode 1113 and a second storage capacitor electrode 1114. The first storage capacitor electrode 1113 is disposed opposite to the first pixel electrode 131 to form a first storage capacitor, thereby maintaining the voltage of the first pixel electrode 131. The second storage capacitor electrode 1114 is disposed opposite to the second pixel electrode 132 to form a second storage capacitor, thereby maintaining the voltage of the second pixel electrode 132.

[0059] The first storage capacitor electrode 1113 and the first pixel electrode 131 at least partially overlap in their orthogonal projections on the substrate 100, and the second storage capacitor electrode 1114 and the second pixel electrode 132 at least partially overlap in their orthogonal projections on the substrate 100. For example, the first storage capacitor electrode 1113 and the second storage capacitor electrode 1114 can be disposed on the gate metal layer 111, that is, on the same layer as the first gate layer 1111 and the second gate layer 1112. For example, as... Figure 3 As shown, the first storage capacitor electrode 1113 can be disposed between the first gate layer 1111 and the second gate layer 1112, and is disposed at intervals from both the first gate layer 1111 and the second gate layer 1112.

[0060] The active layer includes a first active layer 114 and a second active layer 115. The patterned source / drain metal layer 113 includes a first source layer 1131, a first drain layer 1132, a second source layer 1133, and a second drain layer 1134. The first source layer 1131 and the first drain layer 1132 are respectively disposed at both ends of the first active layer 114 and partially overlap with the first active layer 114 to form the first channel region of the first TFT device T1. The first source layer 1131 and the first drain layer 1132 serve as the source and drain of the first TFT, respectively. The first gate layer 1111 is disposed opposite to the first channel region and serves as the gate of the first TFT device T1.

[0061] The second source layer 1133 and the second drain layer 1134 are respectively disposed at both ends of the second active layer 115 and partially overlap with the second active layer 115 to form the second channel region of the second TFT device T2. The second source layer 1133 and the second drain layer 1134 serve as the source and drain of the second TFT, respectively. The second gate layer 1112 is disposed opposite to the second channel region and serves as the gate of the second TFT device T2. The first drain layer 1132 is disposed adjacent to the second source layer 1133 and is connected by a connecting layer disposed between them.

[0062] In addition, the TFT substrate also includes a protective layer 120 disposed between the thin-film transistor layer 110 and the pixel electrode layer 130. A first via 121 and a second via 122 penetrating the protective layer 120 are provided therethrough. The first pixel electrode 131 is connected to the first drain layer 1132 through the first via 121, and the second pixel electrode 132 is connected to the second drain layer 1134 through the second via 122.

[0063] For example, the first via 121 can be located between the first TFT device T1 and the second TFT device T2. In some examples, the orthographic projection of the first via 121 on the substrate 100 can be located within the orthographic projection of the connection layer between the first drain layer 1132 and the second source layer 1133 on the substrate 100, thereby coupling the first pixel electrode 131 to the connection layer, and thus connecting it to the drain of the first TFT device T1 and the source of the second TFT device T2, respectively.

[0064] Considering the proximity of the first drain layer 1132 and the second source layer 1133, the aperture of the first via 121 can be adapted to the spacing between the first drain layer 1132 and the second source layer 1133, that is, the aperture of the first via 121 is less than or equal to this spacing. Since the area of ​​the TFT device region 101 is smaller than the area of ​​the pixel region 102, correspondingly, the size of the first pixel electrode 131 is smaller than the size of the second pixel electrode 132, so the aperture of the first via 121 can also be smaller than the aperture of the second via 122.

[0065] For example, the protective layer 120 can be a passivation layer (PVX) that covers the thin-film transistor layer 110, especially the source / drain metal layer 113 traces of the thin-film transistor layer 110. The passivation layer can be made of inorganic insulating materials such as silicon nitride, silicon oxide, or silicon oxynitride. Alternatively, the protective layer 120 can also include a stacked passivation layer (PVX) and a planarization layer (PLN). Adding a planarization layer increases the thickness of the dielectric material between the thin-film transistor layer 110 and the pixel electrode layer 130, thereby preventing damage to the thin-film transistor layer 110 during subsequent lamination of the electronic paper film, improving the electronic paper's resistance to pressure damage, and ultimately increasing the product yield.

[0066] Secondly, such as Figure 4 As shown in the figure, this specification provides an electronic paper display device, which includes an electronic paper film 42 and a TFT substrate 41 stacked together. The electronic paper film 42 includes a display layer and a transparent conductive layer, with the display layer located between the transparent conductive layer and the TFT substrate 41. The specific structure and effects of the TFT substrate 41 can be referred to the relevant description in the first aspect above, and will not be repeated here.

[0067] For example, the display layer may include multiple microcapsules, each encapsulating charged colored particles. For instance, the display layer may be two-color electronic paper, such as black and white, white and red, or black and red; it may also be three-color electronic paper (such as black, white, and red); or it may be four-color electronic paper (such as black, white, red, and yellow). This embodiment does not impose any limitations on this.

[0068] In use, the transparent conductive layer serves as a common electrode. A driving waveform is applied to the source of the first TFT device by the driving chip, generating an electric field between the transparent conductive layer and the pixel electrode layer, thereby driving the movement of charged colored particles in the corresponding microcapsules to display an image.

[0069] For example, electronic paper display devices can be display products such as billboards, notice boards, labels, watches, mobile phones, and electronic paper readers; this embodiment does not limit this.

[0070] Since the TFT substrate 41 included in the electronic paper display device described in the embodiments of this specification has been described above, those skilled in the art can understand the specific structure and working principle of the electronic paper display device based on the TFT substrate 41 described in the embodiments of this specification, and therefore will not be repeated here. Any electronic paper display device that includes the TFT substrate 41 provided in the embodiments of this specification falls within the scope of protection of this invention.

[0071] Thirdly, embodiments of this specification provide a pixel driving method applied to the electronic paper display device provided in the second aspect above. For example... Figure 5 As shown, the pixel driving method may include the following steps:

[0072] Step S101: Receive the pixel driving signal corresponding to the current frame image. The pixel driving signal includes: a main driving signal segment and a compensation driving signal segment.

[0073] In step S102, during the refresh phase, both the first TFT device and the second TFT device are turned on, and the first pixel electrode and the second pixel electrode are driven by the main drive signal segment to refresh the sub-pixel corresponding to the first pixel electrode and the sub-pixel corresponding to the second pixel electrode.

[0074] In step S103, during the compensation phase, the first TFT device is turned on and the second TFT device is turned off. The first pixel electrode is driven by the compensation drive signal segment to compensate and refresh the sub-pixel corresponding to the first pixel electrode.

[0075] It should be noted that the pixel driving circuit of each pixel unit in the above TFT substrate can be equivalent to as follows: Figure 6 The circuit shown includes a first TFT device T1 and a second TFT device T2. The source of the first TFT device T1 receives the pixel driving signal Source, the gate receives the first gate driving signal Gate n1, and the drain is connected to the source of the second TFT device T2 and the first pixel electrode pixel n1. The gate of the second TFT device T2 receives the second gate driving signal Gaten2, and the drain is connected to the second pixel electrode pixel n2. The first pixel electrode pixel n1 and the common electrode (providing a common voltage Vcom) are equivalent to a capacitor C1, and the second pixel electrode pixel n2 and the common electrode are equivalent to a capacitor C2.

[0076] Because the voltages of the first pixel electrode (pixel n1) and the second pixel electrode (pixel n2) within the same pixel unit can be controlled independently, to further ensure the refresh reliability of sub-pixels in the TFT device area and improve display defects such as poor ghosting tests, red screen with black lines, and black screen with red lines, the pixel driving process can be divided into a refresh stage and a compensation stage, and the driving waveform can be divided into a main driving waveform and a compensation driving waveform. The refresh stage uniformly refreshes the sub-pixels corresponding to the first pixel electrode (pixel n1) and the second pixel electrode (pixel n2), while the compensation stage separately compensates and refreshes the sub-pixels corresponding to the first pixel electrode (pixel n1).

[0077] The refresh process of an electronic paper display consists of three stages: the inversion stage, the shaking stage, and the development stage. For example, for electronic paper containing black and white, the inversion stage displays a black image, the shaking stage displays black and white images alternately to separate black charged particles and white charged particles, and the development stage displays a white image.

[0078] Taking the white area of ​​electronic paper display as an example, Figure 7 The diagram shows a waveform of the pixel drive signal "Source" applied to the source of a first TFT device. It should be noted that... Figure 7 The waveforms shown are for illustrative purposes only and are not intended to be limiting. In step S101, the waveform of the pixel driving signal is the driving waveform corresponding to the current frame image, the waveform of the main driving signal segment is the main driving waveform, and the waveform of the compensation driving signal segment is the compensation driving waveform.

[0079] For example, both the refresh phase and the compensation phase described above can include: a color inversion phase, a dithering phase, and a color development phase. Correspondingly, both the main drive waveform and the compensation drive waveform can include: a phase inversion waveform, a dithering waveform, and a color development waveform.

[0080] When in use, for the same pixel unit, the refresh phase is entered first, followed by the compensation phase.

[0081] During the refresh phase, the main driving waveform takes effect, and the first TFT device T1 and the second TFT device T2 are turned on simultaneously, so that the main driving waveform is applied to the first pixel electrode pixel n1 and the second pixel electrode pixel n2, and the sub-pixels corresponding to the first pixel electrode pixel n1 and the second pixel electrode pixel n2 are refreshed simultaneously.

[0082] During the compensation phase, the compensation driving waveform takes effect, the first TFT device T1 is turned on, and the second TFT device T2 is turned off, so that the compensation driving waveform is applied to the first pixel electrode pixel n1, refreshing the sub-pixel corresponding to the first pixel electrode pixel n1, while the sub-pixel corresponding to the first pixel electrode pixel n1 is not refreshed.

[0083] By compensating and driving the first pixel electrode (pixel n1), the sub-pixels in the TFT area are refreshed, which can improve the color shift problem caused by the weak electric field strength in the TFT area. This effectively improves display problems such as poor Ghosting test, red screen with black lines, and black screen with red lines that occur in actual products, and helps to optimize the display effect of electronic paper display devices.

[0084] Specifically, the compensation drive waveform can be adjusted by the debugger according to the actual test conditions. For example, taking black, white, and red electronic paper as an example, the following four cases are mainly listed, and other cases can be deduced by analogy.

[0085] The first type: If there is no color shift during the test after the refresh phase is completed, then there is no need to add a compensation phase, that is, there is no compensation driving waveform.

[0086] The second scenario: If the test finds that the black area is reddish or has red dots, then a compensation stage needs to be added to increase the shaking time and number of times the first pixel electrode (pixel n1) in the black area is made black.

[0087] The third scenario: If the test finds that the red area is too dark or has black spots, then a compensation stage needs to be added to increase the shaking time and the number of times the first pixel electrode (pixel n1) in the red area is displayed.

[0088] The fourth type: If the test finds that the white area is reddish or has red dots, then a compensation stage needs to be added to increase the shaking time and whitening times of the first pixel electrode (pixel n1) in the white area.

[0089] For example, based on the debugging results, a waveform lookup table can be pre-configured in the electronic paper display device. The waveform lookup table stores the compensation drive waveforms corresponding to different color shift conditions. The driver IC or system on-chip (SOC) retrieves the compensation drive waveform from the lookup table according to the color shift condition of the actual displayed image, and generates a pixel drive signal together with the pre-configured main drive waveform.

[0090] In some examples, the system or IC can add a memory function for the previous frame of the displayed image. By comparing the color changes of each pixel in the current frame image with those in the previous frame image, the compensation driving waveform is determined. For example, the compensation driving waveform can be selected from the waveform lookup table mentioned above, thereby adjusting the compensation driving waveform corresponding to the first pixel unit in each pixel unit of the TFT substrate. The specific process can be configured according to actual needs and will not be detailed here.

[0091] The above description does not provide detailed technical specifications regarding the layout of each layer of the product. However, those skilled in the art should understand that layers and regions of the desired shape can be formed using various technical means. Furthermore, to form the same structure, those skilled in the art can also design methods that are not entirely identical to those described above. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination.

[0092] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of this application may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0093] Furthermore, those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of this disclosure is limited to these examples; within the framework of this disclosure, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of one or more embodiments of this specification as described above, which are not provided in detail for the sake of brevity.

[0094] Although preferred embodiments have been described in this specification, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this specification.

Claims

1. A TFT substrate, characterized in that, include: Substrate; A thin-film transistor layer is stacked on the substrate and includes a first TFT device and a second TFT device corresponding to each pixel unit. The source of the first TFT device is used to receive a pixel driving signal, the drain of the first TFT device is connected to the source of the second TFT device, and the gate of the first TFT device and the gate of the second TFT device are respectively used to receive their respective gate driving signals. as well as A pixel electrode layer is stacked on the thin film transistor layer and includes a first pixel electrode and a second pixel electrode spaced apart. The first pixel electrode is located on the first TFT device and the second TFT device and is connected to the drain of the first TFT device. The second pixel electrode is connected to the drain of the second TFT device. The orthogonal projections of the first TFT device and the second TFT device onto the substrate constitute a first projection region, and the orthogonal projection of the first pixel electrode onto the substrate constitutes a second projection region. The first projection region and the second projection region at least partially overlap.

2. The TFT substrate according to claim 1, characterized in that, The orthographic projection of the channel region of the first TFT device onto the substrate at least partially overlaps with the second projection region, while the orthographic projection of the channel region of the second TFT device onto the substrate does not overlap with the second projection region. The orthographic projection of the second pixel electrode on the substrate is the third projection region, and the orthographic projection of the channel region of the second TFT device on the substrate does not overlap with the third projection region.

3. The TFT substrate according to claim 1, characterized in that, The orthographic projection of the gate of the first TFT device on the substrate at least partially overlaps with the second projection area, while the orthographic projection of the gate of the second TFT device on the substrate does not overlap with the second projection area. The orthogonal projection of the second pixel electrode on the substrate is the third projection region, and the orthogonal projection of the gate of the second TFT device on the substrate does not overlap with the third projection region.

4. The TFT substrate according to claim 1, characterized in that, The sum of the areas of the first pixel electrode and the second pixel electrode accounts for more than 76% of the area of ​​the pixel unit.

5. The TFT substrate according to claim 1, characterized in that, The thin-film transistor layer further includes a first storage capacitor electrode and a second storage capacitor electrode, wherein the first storage capacitor electrode is disposed opposite to the first pixel electrode to form a first storage capacitor, and the second storage capacitor electrode is disposed opposite to the second pixel electrode to form a second storage capacitor.

6. The TFT substrate according to claim 1, characterized in that, Also includes: A protective layer is disposed between the thin-film transistor layer and the pixel electrode layer, and a first via and a second via are disposed on the protective layer; The thin-film transistor layer includes: a gate metal layer, a gate insulating layer, an active layer, and a source / drain metal layer sequentially stacked on the substrate, wherein the source / drain metal layer includes a first drain layer serving as the drain of the first TFT device and a second drain layer serving as the drain of the second TFT device. The first pixel electrode is connected to the first drain layer through the first via, and the second pixel electrode is connected to the second drain layer through the second via.

7. The TFT substrate according to claim 6, characterized in that, The first via is located between the first TFT device and the second TFT device, and the diameter of the first via is smaller than the diameter of the second via.

8. The TFT substrate according to claim 1, characterized in that, Also includes: First gate drive circuit and second gate drive circuit. The output terminal of the first gate driving circuit is connected to the gate of the first TFT device to provide a first gate driving signal to the gate of the first TFT device. The output of the second gate driving circuit is connected to the gate of the second TFT device, providing a second gate driving signal to the gate of the second TFT device.

9. An electronic paper display device, characterized in that, include: The TFT substrate according to any one of claims 1-8.

10. A pixel driving method, characterized in that, The method, applied to the electronic paper display device of claim 9, comprises: Receive the pixel driving signal corresponding to the current frame image. The pixel driving signal includes: a main driving signal segment and a compensation driving signal segment. During the refresh phase, both the first TFT device and the second TFT device are turned on, and the first pixel electrode and the second pixel electrode are driven by the main driving signal segment to refresh the sub-pixel corresponding to the first pixel electrode and the sub-pixel corresponding to the second pixel electrode. During the compensation phase, the first TFT device is turned on and the second TFT device is turned off. The first pixel electrode is driven by the compensation drive signal segment to compensate and refresh the sub-pixel corresponding to the first pixel electrode.

11. The method according to claim 10, characterized in that, Both the refresh phase and the compensation phase include: a color inversion phase, a dithering phase, and a color rendering phase.

12. The method according to claim 10, characterized in that, The waveform of the compensation drive signal segment is determined by comparing the color changes of each pixel corresponding to the current frame image with those of the previous frame image.

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