Display panel, control method thereof, and electronic paper display device

Abstract

The application provides a display panel, a control method thereof and an electronic paper display device. The display panel comprises a common electrode layer, a liquid crystal layer group and an array substrate. The liquid crystal layer group comprises a plurality of liquid crystal layers arranged in sequence. The color light reflected by each liquid crystal layer is different from each other, and the threshold voltage of at least two liquid crystal layers is different from each other. The array substrate and the common electrode layer are arranged on the opposite sides of the liquid crystal layer along the stacking direction. The array substrate and the common electrode layer are configured to form a driving electric field on the liquid crystal layer group to selectively control the optical state of each liquid crystal layer. By using a single set of array substrate and common electrode layer and utilizing the characteristic that the threshold voltages of at least two liquid crystal layers are different from each other, the array substrate does not need to be arranged for each liquid crystal layer, thereby reducing the thickness of the display panel.

Description

Technical Field

[0001] This application relates to the field of display technology, and in particular to a display panel and its control method, and an electronic paper display device. Background Technology

[0002] Existing cholesteric liquid crystal color electronic paper technology cannot meet the requirements of high-resolution display and thin structure: planar RGB (red, green, blue) structure causes optical crosstalk and brightness loss, while multi-layer stacking solution requires sacrificing panel thickness. Summary of the Invention

[0003] The main technical problem addressed by this application is to provide a display panel and its control method, as well as an electronic paper display device, thereby solving the problem that multi-layer stacking schemes in the prior art require sacrificing panel thickness.

[0004] To address the aforementioned technical problems, the first technical solution provided in this application is: to provide a display panel, comprising: Common electrode layer; A liquid crystal layer group includes multiple liquid crystal layers stacked sequentially; each liquid crystal layer can reflect different colors of light, and at least two liquid crystal layers have different threshold voltages. An array substrate and a common electrode layer are respectively disposed on opposite sides of the liquid crystal layers along the stacking direction; the array substrate and the common electrode layer are configured to form a driving electric field on the liquid crystal layer group to selectively control the optical state of each liquid crystal layer.

[0005] In some embodiments, the absolute value of the threshold voltage difference between any two liquid crystal layers is greater than 2V.

[0006] In some embodiments, the threshold voltage of each liquid crystal layer varies monotonically along the stacking direction.

[0007] In some embodiments, the common electrode layer is located on the light-emitting side of the liquid crystal layer; the display panel also includes a reflective backplate disposed on the side of the array substrate away from the common electrode layer.

[0008] In some embodiments, the liquid crystal layer is a cholesteric liquid crystal layer, and the threshold voltage of each liquid crystal layer increases sequentially in the direction from the array substrate toward the common electrode layer.

[0009] In some embodiments, the liquid crystal layer group further includes a transparent insulating layer disposed between adjacent liquid crystal layers.

[0010] In some embodiments, the liquid crystal layer group includes three liquid crystal layers for reflecting red light, green light, and blue light, respectively.

[0011] To solve the above-mentioned technical problems, the second technical solution provided in this application is: a method for controlling a display panel, used to control the aforementioned display panel, comprising: By applying driving voltages of different amplitudes to the liquid crystal layer group through the array substrate and the common electrode layer, the optical state of each liquid crystal layer can be selectively controlled.

[0012] In some embodiments, driving voltages of different amplitudes are applied to the liquid crystal layer group through the array substrate and the common electrode layer to selectively control the optical state of each liquid crystal layer, including: A first voltage is applied to the common electrode layer, and a second voltage of different amplitudes is applied to the array substrate to selectively control the optical state of each liquid crystal layer.

[0013] To solve the above-mentioned technical problems, the third technical solution provided in this application is: to provide an electronic paper display device, which includes a driving circuit and the above-mentioned display panel, wherein the driving circuit is used to apply driving voltages of different amplitudes to the liquid crystal layer group through the array substrate and the common electrode layer.

[0014] The beneficial effects of this application are as follows: Unlike existing technologies, this application provides a display panel and its control method, as well as an electronic paper display device. The display panel includes a common electrode layer, a liquid crystal layer group, and an array substrate. The liquid crystal layer group includes multiple liquid crystal layers stacked sequentially; each liquid crystal layer reflects a different color of light, and at least two of the liquid crystal layers have different threshold voltages. The array substrate and the common electrode layer are respectively disposed on opposite sides of the liquid crystal layers along the stacking direction. The array substrate and the common electrode layer are configured to form a driving electric field on the liquid crystal layer group to selectively control the optical state of each liquid crystal layer. By using a single array substrate and common electrode layer, and utilizing the different threshold voltage characteristics of at least two liquid crystal layers, it is unnecessary to set up a separate array substrate for each liquid crystal layer, thereby reducing the thickness of the display panel. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of the first embodiment of the display panel provided in this application; Figure 2 This is a schematic diagram of the structure of the second embodiment of the display panel provided in this application; Figure 3 This is a schematic diagram of the structure of the third embodiment of the display panel provided in this application; Figure 4 This is a schematic diagram of an embodiment of the common electrode layer, TFT array, and driving circuit provided in this application; Figure 5 This is a schematic diagram of the structure of a display panel in related technologies; Figure 6 yes Figure 5 A schematic diagram of the structure of the common electrical layer, TFT array, and driver chip; Figure 7 This is a schematic diagram of an embodiment of the electronic paper display device provided in this application; Figure 8 This is a schematic flowchart of one embodiment of the method for manufacturing the electronic paper display device provided in this application; Figure 9 This is a schematic diagram of the fabrication structure of an embodiment of the array substrate provided in this application; Figure 10 This is a schematic diagram of the fabrication structure of one embodiment of the common electrode layer provided in this application; Figure 11 This is a schematic diagram of the fabrication structure of one embodiment of the reflective backplate provided in this application; Figure 12 This is a schematic diagram of the structure of an embodiment of step S11 provided in this application; Figure 13 This is a schematic diagram of the structure of an embodiment of step S12 provided in this application; Figure 14 This is a schematic diagram of the assembly structure of one embodiment of the electronic paper display device provided in this application; Figure 15 This is a flowchart illustrating the control method for the display panel provided in this application; Figure 16 yes Figure 15 A flowchart illustrating the implementation method of step S0; Figure 17 This is a schematic diagram of an embodiment of a pixel unit displaying black provided in this application; Figure 18 This is a schematic diagram of one embodiment of the pixel unit displaying red provided in this application; Figure 19 This is a schematic diagram of an embodiment of the pixel unit displaying yellow provided in this application; Figure 20 This is a schematic diagram of an embodiment of a pixel unit displaying white according to the present application.

[0017] Explanation of icon numbers: 100. Display panel; 10. Liquid crystal layer group; 11. Liquid crystal layer; 110. Liquid crystal unit; 112. Spacer layer; 113. Pixel unit; 20. Common electrode layer; 30. Array substrate; 40. Reflective backplate; 50. Transparent insulating layer; 60. Conductive structure; 70. Cover plate; 200. Driving circuit; 1. Electronic paper display device; 101. Substrate; 102. Ink layer; 103. Composite layer. Detailed Implementation

[0018] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0019] In the following description, specific details such as particular system architectures, interfaces, and technologies are presented for illustrative purposes rather than for limiting purposes, in order to provide a thorough understanding of this application.

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] The terms "first," "second," and "third" in this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. All directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationships and movements between components in a specific orientation (as shown in the figures). If the specific orientation changes, the directional indications also change accordingly. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0022] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0023] Please see Figure 1 , Figure 1 This is a structural schematic diagram of the first embodiment of the display panel provided in this application.

[0024] This application provides a display panel 100, which includes a common electrode layer 20, a liquid crystal layer group 10, and an array substrate 30. The liquid crystal layer group 10 includes a plurality of liquid crystal layers 11 stacked sequentially; each liquid crystal layer 11 can reflect different colors of light, and at least two liquid crystal layers 11 have different threshold voltages; the array substrate 30 and the common electrode layer 20 are respectively disposed on opposite sides of the liquid crystal layers 11 along the stacking direction; the array substrate 30 and the common electrode layer 20 are configured to form a driving electric field on the liquid crystal layer group 10 to selectively control the optical state of each liquid crystal layer 11.

[0025] By using a single array substrate 30 and a common electrode layer 20, and taking advantage of the different threshold voltage characteristics of at least two liquid crystal layers 11, it is not necessary to set up an array substrate 30 for each liquid crystal layer 11, thereby reducing the thickness of the display panel 100.

[0026] For example, the display panel 100 is an electronic paper display.

[0027] The common electrode layer 20 can be a continuous structure; or the common electrode layer 20 can include multiple independent sub-electrodes, each of which is independently controlled.

[0028] For example, the common electrode layer 20 is a continuous structure, which does not require complex photolithography patterns and can greatly reduce the complexity of the manufacturing process.

[0029] The common electrode layer 20 is a transparent conductive film.

[0030] In some embodiments, for example, the common electrode layer 20 may be made of a transparent conductive oxide such as ITO (indium tin oxide).

[0031] For example, the transmittance of the common electrode layer 20 is greater than or equal to 85% so as not to affect the light reflection and display effect.

[0032] The optical state includes a first optical state and a second optical state. In the first optical state, the liquid crystal unit 110 exhibits reflective properties for light of a preset wavelength. In the second optical state, the liquid crystal unit 110 exhibits transmissive properties for light of a preset wavelength.

[0033] A driving signal with a potential difference is applied to the array substrate 30 and the common electrode layer 20 to form a driving voltage on the liquid crystal layer group 10. When the driving voltage applied to the liquid crystal layer 11 meets the triggering condition based on the threshold voltage, the optical state of the corresponding liquid crystal layer 11 is switched, while the other liquid crystal layers 11 maintain their original optical state.

[0034] In some embodiments, when the driving voltage is less than the threshold voltage, the corresponding liquid crystal cell 110 is in a first optical state, and when the driving voltage is greater than or equal to the threshold voltage, the corresponding liquid crystal cell 110 is in a second optical state. For example, when the liquid crystal layer 11 is a cholesteric liquid crystal layer, the cholesteric liquid crystal layer refers to a liquid crystal material with bistable properties, which can maintain its optical state without continuous power supply after power is turned off.

[0035] In other embodiments, when the driving voltage is greater than or equal to the threshold voltage, the corresponding liquid crystal cell 110 is in a first optical state; when the driving voltage is less than the threshold voltage, the corresponding liquid crystal cell 110 is in a second optical state. The liquid crystal layer 11 can be another liquid crystal material layer.

[0036] In some embodiments, the common electrode layer 20 is located on the light-emitting side of the liquid crystal layer 11.

[0037] The common electrode layer 20 is located on the light-emitting side of the liquid crystal layer 11, meaning that relative to the array substrate 30, the common electrode layer 20 faces the observer, ensuring that light reflected from the liquid crystal layer 11 passes directly through the common electrode layer 20 and is emitted.

[0038] The common electrode layer 20 is located on the light-emitting side of the liquid crystal layer 11, which minimizes the light reflection path, reduces light absorption and scattering, and thus improves display brightness.

[0039] This application designs a bottom array substrate 30 and a top common electrode layer 20, eliminating the intermediate pixel electrode, multilayer TFT array 31 and color filter set between liquid crystal layers 11, so that the total thickness of the display panel 100 can be controlled within 0.3mm (taking the liquid crystal layer group 10 including three liquid crystal layers 11 as an example), which is superior to the thin and light performance of the existing multilayer electrode stacking scheme.

[0040] In some embodiments, the common electrode layer 20 is located on the light-emitting side of the liquid crystal layer 11. The display panel 100 also includes a reflective back plate 40, which is disposed on the side of the array substrate 30 away from the common electrode layer 20.

[0041] The surface of the reflective backplate 40 facing the liquid crystal layer 11 is black. Specifically, when displaying black, each liquid crystal layer 11 is in a second optical state, and incident light passes through the liquid crystal layer 11. At this time, the display panel 100 directly displays the color (black) of the reflective backplate 40. When different amplitude driving voltages are applied, the corresponding liquid crystal layer 11 reflects light of a specific wavelength.

[0042] The reflective backplate 40 can be a single-layer structure or a multi-layer structure, depending on the actual needs.

[0043] For example, the reflective backplate 40 is a single-layer structure.

[0044] For example, black ink can be uniformly sprayed onto the surface of a PET (polyethylene terephthalate) film as a reflective backplate 40 using a spraying process; carbon black ink or metal oxide ink can also be used.

[0045] By setting a reflective backplate 40, the color of the reflective backplate 40 is directly reflected when the display is in a dark state, thereby achieving a pure black display, which helps to improve the display contrast.

[0046] In other embodiments, the array substrate 30 may be disposed on the light-emitting side of the liquid crystal layer 11, and the reflective backplate 40 may be disposed on the side of the common electrode layer 20 away from the liquid crystal layer 11.

[0047] In some embodiments, the array substrate 30 includes a plurality of pixel electrodes, and each liquid crystal layer 11 includes a plurality of liquid crystal cells 110; in each liquid crystal layer 11, the liquid crystal cells 110 are disposed in a one-to-one correspondence with the pixel electrodes; the pixel electrodes and the common electrode layer 20 are configured to form a driving electric field on the liquid crystal layer group 10 to selectively control the optical state of the liquid crystal cells 110 between them. Each liquid crystal cell 110 in the same liquid crystal layer 11 can reflect the same color of light, that is, a single liquid crystal layer 11 can reflect one color of light. The thicknesses of different liquid crystal layers 11 can be the same or different. The liquid crystal cells 110 corresponding to a single pixel electrode constitute a pixel unit 113, and the number of liquid crystal cells 110 included in each pixel unit 113 is the same as the number of liquid crystal layers 11. For example, if there are three liquid crystal layers 11, then each pixel unit 113 includes three liquid crystal cells 110 that can reflect different colors of light. Figure 1 As shown, each column of liquid crystal cells 110 along the stacking direction constitutes a pixel cell 113.

[0048] Specifically, a driving signal with a potential difference is applied to the pixel electrode and the common electrode layer 20 of the array substrate 30 to form a driving voltage on the liquid crystal layer group 10. When the driving voltage applied to the liquid crystal layer 11 meets the triggering condition based on the threshold voltage, the optical state of the corresponding liquid crystal cell 110 is switched, while other liquid crystal cells 110 maintain their original optical state, thereby realizing pixel-level control.

[0049] Furthermore, in some embodiments, the liquid crystal layer 11 further includes a spacer layer 112 disposed between the liquid crystal cells 110. The spacer layer 112 is used to physically isolate adjacent liquid crystal cells 110.

[0050] For example, the spacer layer 112 has a light-shielding function to prevent lateral crosstalk between liquid crystal cells 110.

[0051] In some embodiments, the absolute value of the threshold voltage difference between any two liquid crystal layers 11 is greater than 2V.

[0052] For example, taking the switching of liquid crystal cell 110 to the first optical state when the driving voltage is greater than or equal to the threshold voltage as an example, assuming that the threshold voltage of the liquid crystal layer 11 that can reflect red light (i.e., the R layer) is 6V, the threshold voltage of the liquid crystal layer 11 that can reflect green light (i.e., the G layer) is 11V, and the threshold voltage of the liquid crystal layer 11 that can reflect blue light (i.e., the B layer) is 16V, then when the driving voltage is in the range of 5V to 10V, only the liquid crystal layer 11 that can reflect red light will respond, while other liquid crystal layers 11 will not trigger, avoiding interlayer crosstalk caused by voltage fluctuations, thereby accurately realizing display states such as R layer reflecting alone and R+G layer mixed reflection. That is, setting the threshold voltage difference to be greater than 2V provides a sufficient safety margin to prevent non-target liquid crystal layers 11 from responding erroneously and ensure the stability of display state switching.

[0053] It should be noted that, for ease of explanation, the liquid crystal layer 11 that can reflect red light is referred to as the R layer, the liquid crystal layer 11 that can reflect green light is referred to as the G layer, and the liquid crystal layer 11 that can reflect blue light is referred to as the B layer.

[0054] By setting the absolute value of the threshold voltage difference between any two liquid crystal layers 11 to be greater than 2V, the interlayer electric field distribution is made more stable, which helps to avoid interlayer crosstalk during voltage switching and thus improves the display resolution. Furthermore, when an intermediate voltage is applied, only the target liquid crystal cell 110 responds, which is beneficial for achieving precise pixel-level color control. The target liquid crystal cell 110 is the liquid crystal cell 110 that needs to switch optical states under the current driving voltage.

[0055] In some embodiments, the threshold voltage of each liquid crystal layer 11 varies monotonically along the stacking direction.

[0056] In some specific embodiments, the threshold voltage of each liquid crystal layer 11 exhibits a strictly monotonically changing trend along the stacking direction, meaning that the threshold voltages of each liquid crystal layer 11 are different from each other. For example, taking the switching of the corresponding liquid crystal cell 110 to the first optical state when the driving voltage is greater than or equal to the threshold voltage as an example, such as... Figure 1 As shown, the liquid crystal layer group 10 includes three liquid crystal layers 11 stacked sequentially, namely layer B, layer G, and layer R. The threshold voltage set for layer R is 5V, the threshold voltage set for layer G is 10V, and the threshold voltage set for layer B is 15V. This allows the liquid crystal cells 110 in the corresponding pixel unit 113 to be in the second optical state when a driving voltage of 0V is applied, so that the pixel unit 113 displays black. When a driving voltage of 5V is applied, only layer R reflects red light, so that the corresponding pixel unit 113 displays red. When a driving voltage of 10V is applied, layer R and layer G reflect light synchronously and then mix the light, so that the corresponding pixel unit 113 displays yellow. When a driving voltage of 15V is applied, the liquid crystal cells 110 in the corresponding pixel unit 113 are all in the first optical state, and reflect light and then mix the light, so that the corresponding pixel unit 113 displays white. The display state remains unchanged after power is turned off, thereby realizing a pixel-level four-color display state.

[0057] It should be noted that if the display panel 100 displays in monochrome, the optical states of each liquid crystal unit 110 in each liquid crystal layer 11 are the same; if the display panel 100 performs pixel-level independent control, the optical states of each liquid crystal unit 110 in each liquid crystal layer 11 can be the same or different.

[0058] For simplicity, the R-layer reflection in this application refers to the reflection of the liquid crystal cell 110 in the corresponding pixel unit 113 that is capable of reflecting red light, rather than the synchronous reflection of all liquid crystal cells 110 in the liquid crystal layer 11 capable of reflecting red light. The G-layer reflection in this application refers to the reflection of the liquid crystal cell 110 in the corresponding pixel unit 113 that is capable of reflecting green light, rather than the synchronous reflection of all liquid crystal cells 110 in the liquid crystal layer 11 capable of reflecting green light. The B-layer reflection in this application refers to the reflection of the liquid crystal cell 110 in the corresponding pixel unit 113 that is capable of reflecting blue light, rather than the synchronous reflection of all liquid crystal cells 110 in the liquid crystal layer 11 capable of reflecting blue light.

[0059] Please see Figures 1 to 3 , Figure 2 This is a schematic diagram of the structure of the second embodiment of the display panel provided in this application. Figure 3 This is a structural schematic diagram of the third embodiment of the display panel provided in this application.

[0060] In some other specific embodiments, the threshold voltage of each liquid crystal layer 11 exhibits a non-strictly monotonic variation along the stacking direction, that is, the threshold voltages of some adjacent liquid crystal layers 11 are the same. For example, taking the switching of the corresponding liquid crystal cell 110 to the first optical state when the driving voltage is greater than or equal to the threshold voltage as an example, such as... Figure 2 As shown, the liquid crystal layer group 10 includes three liquid crystal layers 11 stacked sequentially, namely layer B, layer G, and layer R. The threshold voltage set for layer R is 5V, the threshold voltage set for layer G is 5V, and the threshold voltage set for layer B is 15V. This ensures that when a driving voltage of 0V is applied, the liquid crystal cells 110 in the corresponding pixel unit 113 are all in the second optical state so that the pixel unit 113 displays black. When a driving voltage of 10V is applied, layer R and layer G reflect and mix light synchronously so that the corresponding pixel unit 113 displays yellow. When a driving voltage of 15V is applied, the liquid crystal cells 110 in the corresponding pixel unit 113 are all in the first optical state, reflect and mix light so that the corresponding pixel unit 113 displays white. The display state remains unchanged after power is turned off, thereby realizing a pixel-level three-color display state.

[0061] By setting the threshold voltage of each liquid crystal layer 11 to vary monotonically along the stacking direction, the switching of multi-color display states at the pixel level can be achieved, that is, independent color control at the pixel level can be realized.

[0062] In some embodiments, the common electrode layer 20 is located on the light-emitting side of the liquid crystal layer 11; the liquid crystal layer 11 is a cholesteric liquid crystal layer, and the threshold voltage of each liquid crystal layer 11 increases sequentially in the direction from the array substrate 30 toward the common electrode layer 20.

[0063] For example, the liquid crystal layer group 10 includes three liquid crystal layers 11 for reflecting red, green, and blue light, respectively. The vertical stacking structure of the three liquid crystal layers 11 achieves no planar crosstalk and no filter light loss, resulting in monochrome display purity far exceeding that of filter-type and planar side-by-side electronic paper. Specifically, the R layer reflects 620±20 nm red light, the G layer reflects 530±20 nm green light, and the B layer reflects 460±20 nm blue light; the reflection bands of each liquid crystal layer 11 do not overlap. The R, G, and B layers are stacked sequentially from the array substrate 30 toward the common electrode layer 20, with the threshold voltage increasing sequentially. For example, the threshold voltage of the B layer is set to 15V, the threshold voltage of the G layer to 10V, and the threshold voltage of the R layer to 5V, or the threshold voltage of the B layer is set to 18V, the threshold voltage of the G layer to 10V, and the threshold voltage of the R layer to 6V, etc.

[0064] By designing the threshold voltage of each liquid crystal layer 11 to increase sequentially in the direction from the array substrate 30 toward the common electrode layer 20 (the common electrode layer 20 faces the observer), the threshold voltage differentiation and electric field distribution are precisely matched, avoiding interlayer crosstalk, thereby achieving pixel-level independent color control, which is beneficial to solving the color crosstalk and resolution loss problems caused by planar RGB structures.

[0065] In other embodiments, such as Figure 3As shown, the liquid crystal layer group 10 includes two stacked liquid crystal layers 11, and the threshold voltages of the two liquid crystal layers 11 are different from each other. The liquid crystal layer group 10 may also include three or more stacked liquid crystal layers 11.

[0066] The number of liquid crystal layers 11, the colors of light that each liquid crystal layer 11 can reflect, their set threshold voltages, and the stacking order of the liquid crystal layers 11 corresponding to the colors of light that can be reflected can be selected according to the color display requirements. For example, taking a cholesteric liquid crystal layer 11 as an example, and the liquid crystal layer group 10 including an R layer and a G layer, the arrangement of the R layer and the G layer is as follows: Figure 3 As shown, in some embodiments, to achieve pixel-level red display, the threshold voltage set for the R layer is greater than the threshold voltage set for the G layer. For example, the threshold voltage of the R layer is set to 10V and the threshold voltage of the G layer is set to 5V. When the driving voltage is less than 5V, the G layer and the R layer synchronously reflect and mix light to make the corresponding pixel unit 113 display yellow. When the driving voltage is greater than 5V and less than 10V, the R layer reflects red light to make the corresponding pixel unit 113 display red. When the driving voltage is greater than 10V, the G layer and the R layer are in a second optical state to make the corresponding pixel unit 113 display black. In other embodiments, to achieve pixel-level green display, the threshold voltage set for the G layer is greater than the threshold voltage set for the R layer. For example, the threshold voltage of the G layer is set to 10V and the threshold voltage of the R layer is set to 5V. When the driving voltage is less than 5V, the G layer and the R layer synchronously reflect and mix light to make the corresponding pixel unit 113 display yellow. When the driving voltage is greater than 5V and less than 10V, the G layer reflects green light to make the corresponding pixel unit 113 display green. When the driving voltage is greater than 10V, the G layer and the R layer are in a second optical state to make the corresponding pixel unit 113 display black.

[0067] In some embodiments, the liquid crystal layer group 10 further includes a transparent insulating layer 50 disposed between adjacent liquid crystal layers 11.

[0068] The transparent insulating layer 50 can be made of a highly transparent insulating material, such as photoresist or polyimide.

[0069] The thickness of the transparent insulating layer 50 is less than or equal to 3 micrometers.

[0070] For example, the transparent insulating layer 50 is a transparent polyimide (PI) or photoresist film layer, which has both >90% light transmittance and excellent dielectric insulation properties, effectively blocking the leakage current path between liquid crystal layers 11 and avoiding interlayer electric field crosstalk; at the same time, it accurately maintains the uniformity of the electric field distribution of the series structure, ensuring that the series voltage distribution characteristics are stable and undamaged.

[0071] The transparent insulating layer 50 can be a single-layer structure or a multi-layer structure, depending on the actual needs.

[0072] For example, the transparent insulating layer 50 is a single-layer structure.

[0073] In some embodiments, the display panel 100 further includes a cover plate 70 disposed on the side of the common electrode layer 20 away from the array substrate 30.

[0074] Please see Figures 1 to 6 , Figure 4 This is a schematic diagram of an embodiment of the common electrode layer, TFT array, and driving circuit provided in this application. Figure 5 This is a schematic diagram of the structure of a display panel in related technologies. Figure 6 yes Figure 5 A schematic diagram of the structure of the common electrode layer, TFT array and driver chip.

[0075] This application sets a transparent insulating layer 50 between the liquid crystal layers 11 instead of the array substrate 30, directly reuses the mature process of the array substrate 30 of existing black and white electronic paper, without adding mask and photolithography processes, which reduces the difficulty of mass production and has significant cost advantages. Compared with the traditional multilayer thin film transistor array stacking solution, the overall cost is reduced by more than 30%.

[0076] Addressing the common practice of using 0.4mm glass substrates as the array substrate 30, this application innovatively adopts a single-layer array substrate 30 driving scheme, eliminating the need for a separate array substrate 30 for each liquid crystal layer 11 in traditional multilayer stacking solutions. By optimizing the film layer structure design, the overall thickness of the display panel 100 can be reduced. This design reduces the thickness of the display panel 100, making it suitable for thickness-sensitive terminal applications such as electronic price tags and e-books. For example, assuming the liquid crystal layer 11 has three layers, compared to the traditional multilayer stacking scheme, this application reduces the overall thickness of the display panel 100 by 0.8mm by eliminating two array substrates 30, while also reducing the cost of two array substrates 30.

[0077] The array substrate 30 refers to a substrate with an integrated thin-film transistor (TFT) array, wherein the TFT array 31 serves as its core driving structure and is used to control the switching state of each pixel.

[0078] In terms of static power consumption, such as Figure 5 and Figure 6 As shown, the traditional solution requires an independent TFT array 31 for the three independent liquid crystal display layers R / G / B. Even in static display, the standby voltage of the multi-layer TFTs (1.5–2.5μW / cm²) still needs to be maintained to lock the display state and suppress inter-layer crosstalk. However, this application uses a single-layer TFT array 31 for driving, and the static power consumption is reduced to 0.5–0.8μW / cm² (only 1 / 3 of the traditional optimized solution).

[0079] Regarding dynamic power consumption, traditional solutions require synchronous driving of the three-layer TFT array 31 and 1–2 calibrations when switching screens (power consumption of 80~120μJ / cm² per switch). This application, however, uses an electrical threshold voltage differentiation driving technology, which only requires applying a single voltage to a single-layer TFT and utilizes the electric field distribution characteristics of the series capacitor to achieve selective triggering of the multi-layer liquid crystal layer 11. No timing synchronization or calibration is required, and the power consumption of a single screen switch (arbitrary color switch) is only 5~8μJ / cm², which is more than 93.3% lower than the traditional solution (less than 1 / 16).

[0080] Please see Figure 1 and Figure 7 , Figure 7 This is a schematic diagram of an embodiment of the electronic paper display device provided in this application.

[0081] This application provides an electronic paper display device 1, which includes a driving circuit 200 and the aforementioned display panel 100. The driving circuit 200 is used to apply driving voltages of different amplitudes to the liquid crystal layer group 10 through the array substrate 30 and the common electrode layer 20.

[0082] The driving circuit 200 is connected to the array substrate 30 and the common electrode layer 20 respectively to apply voltage signals to them.

[0083] For example, the driving circuit 200 is electrically connected to the array substrate 30 via a chip-on-film (COF) bonding process. The driving circuit 200 is electrically connected to the common electrode layer 20 via the array substrate 30. Specifically, the display panel 100 also includes a conductive structure 60 (see...). Figure 14 The conductive structure 60 is disposed between the common electrode layer 20 and the array substrate 30, and the conductive structure 60 connects the driving circuit 200 and the common electrode layer 20.

[0084] The drive circuit 200 can support multiple voltage outputs and the timing control accuracy can be 1ms.

[0085] In traditional multilayer stacking schemes, one array substrate 30 requires one COF. This application uses a single array substrate 30, which can reduce the number of COFs, thereby reducing material and packaging costs.

[0086] The driving circuit 200 includes a driving chip. In conventional multilayer stacking schemes, each array substrate 30 requires one driving chip, and multiple array substrates 30 require multiple driving chips. This application uses a single array substrate 30, which reduces the number of driving chips.

[0087] For example, taking the liquid crystal layer 11 as a three-layer structure, a comprehensive calculation shows that each display panel 100 can be reduced by 18 yuan (approximately a 15% cost reduction).

[0088] Please see Figures 8 to 14 , Figure 8 This is a schematic flowchart of one embodiment of the method for manufacturing the electronic paper display device provided in this application. Figure 9 This is a schematic diagram of the fabrication structure of an embodiment of the array substrate provided in this application. Figure 10 This is a schematic diagram of the fabrication structure of one embodiment of the common electrode layer provided in this application. Figure 11 This is a schematic diagram illustrating the fabrication structure of one embodiment of the reflective backplate provided in this application. Figure 12 This is a schematic diagram of the structure of an embodiment of step S11 provided in this application. Figure 13 This is a schematic diagram of the structure of an embodiment of step S12 provided in this application. Figure 14 This is a schematic diagram of the assembly structure of one embodiment of the electronic paper display device provided in this application.

[0089] This application provides a method for manufacturing an electronic paper display device 1, used to manufacture the aforementioned electronic paper display device 1. The method for manufacturing the electronic paper display device 1 includes: S1: A liquid crystal layer group 10 is disposed on the array substrate 30; S2: A common electrode layer 20 is provided on the liquid crystal layer group 10.

[0090] In some implementations, such as Figure 9 As shown, a TFT array 31 is fabricated on a substrate 101 to form an array substrate 30. Exemplarily, the TFT array 31 is an amorphous silicon thin-film transistor array. Exemplarily, the pixel size is 150μm × 150μm, the pixel pitch is 20μm, and the process temperature is ≤100℃.

[0091] In some implementations, such as Figure 10 As shown, a transparent conductive film is deposited on the surface of a substrate 101 to form a common electrode layer 20. For example, the transparent conductive film is an ITO film with a thickness of 100 nm, which is deposited by magnetron sputtering and then annealed at ≤80°C.

[0092] In some embodiments, the method for manufacturing the electronic paper display device 1 further includes: S3: A reflective backplate 40 is provided on one side of the array substrate 30.

[0093] For example, such as Figure 11 As shown, the reflective backplate 40 has a double-layer structure, and a black ink layer 102 is sprayed onto the substrate 101 to form the reflective backplate 40.

[0094] Steps S1 and S3 are not in any particular order.

[0095] In some embodiments, the transparent insulating layer 50 has a double-layer structure. For example, a 2-micrometer-thick photoresist is spin-coated onto a substrate 101 and cured with ultraviolet light to form the transparent insulating layer 50.

[0096] For example, the substrate 101 is a PET flexible substrate. The substrate 101 uses a flexible substrate to ensure overall flexibility and ultra-thinness, and has good light transmittance and mechanical strength, which is suitable for flexible bending scenarios and can avoid the limitations of rigid substrates.

[0097] For example, the thickness of the substrate 101 is less than or equal to 50 micrometers.

[0098] In some embodiments, step S1: forming a liquid crystal layer group 10 on the array substrate 30 includes: Step S11: Prepare a liquid crystal layer 11 on the transparent insulating layer 50 to obtain the composite layer 103; Step S12: Prepare the first liquid crystal layer 11 on the array substrate 30; Step S13: Stack at least one composite layer 103 on the side of the first liquid crystal layer 11 away from the array substrate 30.

[0099] For example, such as Figure 2 As shown, spacer layers 112 are disposed on array substrate 30, and liquid crystal cells 110 are disposed between spacer layers 112 to form a first liquid crystal layer 11.

[0100] For example, such as Figure 2 As shown, a spacer layer 112 is provided on the transparent insulating layer 50, and liquid crystal cells 110 are provided between the spacer layers 112 to obtain a composite layer 103.

[0101] For example, the spacer layer 112 is prepared using photoresist.

[0102] Select the required number of composite layers 103 and stack all the composite layers 103 sequentially on the side of the first liquid crystal layer 11 away from the array substrate 30.

[0103] The liquid crystal cells 110 in each composite layer 103 can reflect the same or different colors of light.

[0104] For example, taking two composite layers 103 as an example, the two composite layers 103 are stacked sequentially on the side of the first liquid crystal layer 11 away from the array substrate 30.

[0105] In some embodiments, the cover plate 70 is disposed on the side of the common electrode layer 20 away from the array substrate 30. The substrate 101 may be omitted between the cover plate 70 and the common electrode layer 20 (see...). Figure 1 Alternatively, the substrate 102 can be retained (see...). Figure 14 ).

[0106] In some specific embodiments, the method further includes, before step S2: forming a conductive structure 60 on the array substrate 30.

[0107] The conductive structure 60 is disposed between the common electrode layer 20 and the array substrate 30, and is used to electrically connect the common electrode layer 20 and the driving circuit 200.

[0108] In some specific embodiments, after step S2, the method further includes connecting the driving circuit 200 to the array substrate 30.

[0109] The driving circuit 200 is electrically connected to the pixel electrodes of the array substrate 30 and to the conductive structure 60. Specifically, the array substrate 30 is provided with connecting leads that connect the conductive structure 60 and the driving circuit 200. That is, the driving circuit 200 is connected to the conductive structure 60 through the connecting leads.

[0110] The driving circuit 200 is electrically connected to the data lines and scan lines of the array substrate 30.

[0111] Please see Figure 1 , Figures 15 to 20 , Figure 15 This is a flowchart illustrating the control method for the display panel provided in this application. Figure 16 yes Figure 15 A flowchart illustrating the implementation method of step S0. Figure 17 This is a schematic diagram illustrating one embodiment of a pixel unit displaying black according to the present application. Figure 18 This is a schematic diagram illustrating one embodiment of the pixel unit displaying red according to this application. Figure 19 This is a schematic diagram of one embodiment of the pixel unit displaying yellow provided in this application. Figure 20 This is a schematic diagram of an embodiment of a pixel unit displaying white according to the present application.

[0112] This application provides a control method for a display panel 100, which is used to control the display panel 100. The control method for the display panel 100 includes: Step S0: Apply driving voltages of different amplitudes to the liquid crystal layer group 10 through the array substrate 30 and the common electrode layer 20 to selectively control the optical state of each liquid crystal layer 11.

[0113] The array substrate 30 and the common electrode layer 20 are located at the bottom and top of the liquid crystal layer group 10, respectively, forming a series capacitor structure. When different driving voltages are applied, the electric field distribution changes with the voltage amplitude. When the driving voltage applied to the liquid crystal layer 11 meets the triggering condition based on the threshold voltage, the optical state of the corresponding liquid crystal layer 11 is switched, while other liquid crystal layers 11 maintain their original optical state.

[0114] In some embodiments, the liquid crystal layer 11 includes a plurality of liquid crystal cells 110, and the array substrate 30 includes a plurality of pixel electrodes. When different driving voltages are applied, the electric field distribution changes with the voltage amplitude. When the driving voltage applied to the liquid crystal cell 110 satisfies the triggering condition based on the threshold voltage, the optical state of the corresponding liquid crystal cell 110 is switched, while other liquid crystal cells 110 maintain their original optical state.

[0115] In some embodiments, step S0: applying driving voltages of different amplitudes to the liquid crystal layer group 10 through the array substrate 30 and the common electrode layer 20 to selectively control the optical state of each liquid crystal layer 11 includes: S10: Apply a first voltage to the common electrode layer 20 and apply a second voltage of different amplitudes to the array substrate 30 to selectively control the optical state of each liquid crystal layer 11.

[0116] A first voltage is applied to the common electrode layer 20, and a second voltage of different amplitudes is applied to the array substrate 30 to obtain driving voltages of different amplitudes, so as to selectively control the optical state of each liquid crystal layer 11.

[0117] For example, taking the case where the liquid crystal cell 110 switches to the first optical state when the driving voltage is greater than or equal to the threshold voltage as an example, the liquid crystal layer group 10 includes three liquid crystal layers 11 stacked sequentially, namely layer B, layer G, and layer R. The threshold voltage set for layer R is 5V, the threshold voltage set for layer G is 10V, and the threshold voltage set for layer B is 15V. A fixed first voltage, such as 0V, is applied to the common electrode layer 20, and a second voltage of different amplitudes, such as 0V, 5V, 10V, or 15V, is applied to the array substrate 30. Figure 17 As shown, when the second voltage is 0V and held for 10ms, all three liquid crystal layers 11 are in the second optical state, displaying black; as Figure 18 As shown, when the second voltage is 5V and maintained for 20ms, only the R layer reflects red light to display red; as Figure 19 As shown, when the second voltage is 10V and held for 25ms, the R layer and G layer synchronously reflect and mix the light to display yellow; as Figure 20 As shown, when the second voltage is 15V and held for 30ms, all three liquid crystal layers 11 reflect and mix light to display white. Furthermore, if a reset is required, the second voltage can be a negative voltage; for example, applying a -5V second voltage resets all liquid crystal cells 110 to the second optical state, preventing image retention.

[0118] The holding time of each driving voltage can be the same or different, depending on the actual needs.

[0119] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0120] The above are merely embodiments of this application and do not limit the scope of patent protection of this application. Any equivalent structural or procedural changes made using the content of this application’s specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of this application.

Claims

1. A display panel, characterized in that, include: Common electrode layer; A liquid crystal layer group, comprising multiple liquid crystal layers stacked sequentially; Each of the liquid crystal layers can reflect different colors of light, and at least two of the liquid crystal layers have different threshold voltages. An array substrate and a common electrode layer are respectively disposed on opposite sides of the liquid crystal layer along the stacking direction; the array substrate and the common electrode layer are configured to form a driving electric field on the liquid crystal layer group to selectively control the optical state of each liquid crystal layer.

2. The display panel according to claim 1, characterized in that, The absolute value of the threshold voltage difference between any two of the liquid crystal layers is greater than 2V.

3. The display panel according to claim 1, characterized in that, The threshold voltage of each liquid crystal layer varies monotonically along the stacking direction.

4. The display panel according to claim 3, characterized in that, The common electrode layer is located on the light-emitting side of the liquid crystal layer; the display panel also includes a reflective backplate, which is disposed on the side of the array substrate away from the common electrode layer.

5. The display panel according to claim 4, characterized in that, The liquid crystal layer is a cholesteric liquid crystal layer, and the threshold voltage of each liquid crystal layer increases sequentially from the array substrate toward the common electrode layer.

6. The display panel according to claim 1, characterized in that, The liquid crystal layer group further includes a transparent insulating layer disposed between adjacent liquid crystal layers.

7. The display panel according to claim 1, characterized in that, The liquid crystal layer group includes three liquid crystal layers respectively used for reflecting red light, green light and blue light.

8. A method for controlling a display panel, used to control the display panel according to any one of claims 1 to 7, characterized in that, include: By applying driving voltages of different amplitudes to the liquid crystal layer group through the array substrate and the common electrode layer, the optical state of each liquid crystal layer can be selectively controlled.

9. The control method for the display panel according to claim 8, characterized in that, The method of applying driving voltages of different amplitudes to the liquid crystal layer group through the array substrate and the common electrode layer to selectively control the optical state of each liquid crystal layer includes: A first voltage is applied to the common electrode layer, and a second voltage of different amplitudes is applied to the array substrate to selectively control the optical state of each liquid crystal layer.

10. An electronic paper display device, characterized in that, The display includes a driving circuit and a display panel according to any one of claims 1 to 7, wherein the driving circuit is used to apply driving voltages of different amplitudes to the liquid crystal layer group through the array substrate and the common electrode layer.

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