A pixel structure and its display driving method

Abstract

This invention provides a pixel structure and its display driving method, comprising, from bottom to top: a first metal layer, a first transparent conductive dielectric layer, a first phase change material layer, a second transparent conductive dielectric layer, a second phase change material layer, a third transparent conductive dielectric layer, a second metal layer, and a fourth transparent conductive dielectric layer; the thickness of the first metal layer is within a first preset thickness range, constituting a total reflection layer; the thickness of the second metal layer is within a second preset thickness range, constituting a semi-transparent reflective layer; the other layers serve as dielectric materials, forming a Fabry-Perot resonant cavity with the first and second metal layers; when the physical thickness of the resonant cavity is within a third preset thickness, the pixel structure can selectively reflect different colors of light when the crystal state of either the first or second phase change material layer changes. This invention achieves in-situ switching of multiple reflected colors on a single display pixel, featuring high pixel density and effectively improving the image resolution of reflective display devices.

Description

Technical Field

[0001] This invention belongs to the field of display technology, and more specifically, relates to a pixel structure and its display driving method. Background Technology

[0002] With the development of technology, display technology has become an indispensable part of people's daily lives, and is widely used in smartphones, tablets, televisions, and other devices. The widespread adoption of display technology has also led to increasingly higher demands on the performance of various displays. Currently, people are generally concerned about display devices' resolution, refresh rate, color gamut, and eye-protection features.

[0003] Current common color displays use sub-pixels with red, green and blue primary colors to form a display pixel to reproduce color images. However, this pixel arrangement is not conducive to increasing pixel density and greatly limits the improvement of image resolution in the display. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a display structure and its display driving method, which aims to solve the problem that existing display pixels are composed of multiple sub-pixels, which is not conducive to increasing pixel density and limits the improvement of display image resolution.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a pixel structure comprising, from bottom to top: a first metal layer, a first transparent conductive dielectric layer, a first phase change material layer, a second transparent conductive dielectric layer, a second phase change material layer, a third transparent conductive dielectric layer, a second metal layer, and a fourth transparent conductive dielectric layer;

[0006] The thickness of the first metal layer is within a first preset thickness range, making the first metal layer a total reflective layer;

[0007] The thickness of the second metal layer is within a second preset thickness range, making the second metal layer a semi-transparent reflective layer;

[0008] The first transparent conductive dielectric layer, the first phase change material layer, the second transparent conductive dielectric layer, the second phase change material layer, the third transparent conductive dielectric layer, and the fourth transparent conductive dielectric layer serve as dielectric materials, forming a Fabry-Perot resonant cavity with the first metal layer and the second metal layer;

[0009] When the physical thickness of the Fabry-Perot resonant cavity is at a third preset thickness, the pixel structure can selectively reflect different colors of light when the crystallization state of either the first phase change material layer or the second phase change material layer changes.

[0010] In an optional example, the third preset thickness multiplied by the refractive index of the pixel structure is equal to an integer multiple of the wavelength of light to be selectively reflected by the pixel structure; wherein the refractive index of the pixel structure varies with the crystallization state of the first phase change material layer and the second phase change material layer.

[0011] In one optional example, the first preset thickness range is 100nm-150nm;

[0012] The second preset thickness range is 5nm-20nm.

[0013] In one optional example, the thickness of both phase change material layers is within the range of 70nm-120nm;

[0014] The thickness of the four transparent conductive dielectric layers mentioned above is all within the range of 50nm-200nm.

[0015] In an optional example, the two phase change material layers described above are made of sulfur-based phase change materials.

[0016] In an optional example, the four transparent conductive dielectric layers are made of indium tin oxide or aluminum-doped zinc oxide.

[0017] In an optional example, when the physical thickness of the Fabry-Perot resonant cavity is at a third preset thickness, and the first phase change material layer is GeTe and the second phase change material layer is Sb2S3, if both the first and second phase change material layers are in an amorphous state, the pixel structure can selectively reflect blue light; if both the first and second phase change material layers are in a crystalline state, the pixel structure can selectively reflect green light; and if the first phase change material layer is in a crystalline state and the second phase change material layer is in an amorphous state, the pixel structure can selectively reflect red light.

[0018] In a second aspect, the present invention provides a display driving method for the pixel structure provided in the first aspect, comprising the following steps:

[0019] Applying electrical pulses of different intensities to the pixel structure causes the first phase change material layer and the second phase change material layer to crystallize separately, thereby controlling the crystallization state of the two phase change material layers in the pixel structure and enabling the pixel structure to selectively reflect light of different colors.

[0020] In summary, the technical solutions conceived by this invention have the following beneficial effects compared with the prior art:

[0021] This invention provides a pixel structure and its display driving method. The pixel structure is a multilayer film structure, consisting of, from bottom to top, a substrate layer, a first metal layer, a first transparent conductive dielectric layer, a first phase change material layer, a second transparent conductive dielectric layer, a second phase change material layer, a third transparent conductive dielectric layer, a second metal layer, and a fourth transparent conductive dielectric layer, forming a typical Fabry-Perot resonant cavity. By utilizing the bottom metal electrode layer and the top transparent conductive dielectric layer, the two phase change material layers can be electrothermally heated to achieve various states such as amorphous-amorphous, amorphous-crystalline, and crystalline-crystalline, each with different optical thicknesses. This allows for the selective reflection of different colors of light under a tungsten filament incandescent lamp light source. This invention achieves in-situ switching of at least three reflected colors on a single display pixel, featuring high pixel density and effectively improving the image resolution of reflective display devices. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the pixel arrangement of an electronically controllable, in-situ switchable reflective color display pixel according to an embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the film structure of an electronically controllable, in-situ switchable reflective color display pixel according to an embodiment of the present invention;

[0024] Figure 3 This is the reflection spectrum of the color display pixel obtained by simulation in Embodiment 1 of the present invention;

[0025] Figure 4 This is the chromaticity map of the color display pixels obtained through simulation in Embodiment 1 of the present invention;

[0026] Figure 5 These are the dispersion curves of the refractive index n and extinction coefficient k of the various materials provided by this invention. Detailed Implementation

[0027] For ease of understanding, the English abbreviations and related technical terms used in the embodiments of this application will be explained and described below.

[0028] The embodiments of this application are described below with reference to the accompanying drawings.

[0029] To address the limitations of traditional color displays in high-resolution display, this invention provides an electrically controlled, in-situ switchable reflective color display pixel based on phase change materials, which can be applied to ultra-high resolution passive display devices.

[0030] It should be noted that, based on the principle of the Fabry-Perot resonant cavity, it only allows light of a specific wavelength that is an integer multiple of the optical thickness of the resonant cavity (the product of the film refractive index and the physical thickness) to pass through, thus exhibiting color selectivity. In principle, the pixel structure provided by this invention can selectively reflect at least four different colors of light (crystalline-crystalline, crystalline-amorphous, amorphous-crystalline, and amorphous-amorphous) as the crystal state of the two phase change material layers changes. Under this premise, the thickness of each film layer needs to be controlled under a suitable combination of crystal states to construct the Fabry-Perot resonant cavity and achieve a color selectivity. Furthermore, this structure can exhibit three color selectivities under the remaining three combinations of crystal states.

[0031] It is understandable that, based on the analysis of the above principles, the present invention can theoretically achieve selective reflection of multiple colors, and the same light can be selected by different means through the selection of different phase change materials and the control of the thickness of each thin film. Under the effect of the above principles, the present invention aims to achieve selective reflection of a certain light in a way that is not limited to one implementation method.

[0032] Therefore, for those skilled in the art, any schemes for selective reflection of multiple colors of light achieved by specific technical means under the support of the technical principles of this invention should be covered within the protection scope of this invention.

[0033] Specifically, to vividly illustrate the present invention, the selective reflection of three colors, red, green and blue, is used as an example for explanation. The above example should not be regarded as any substantial limitation on the technical solution protected by the present invention.

[0034] The purpose of this invention is to provide an electrically controlled, in-situ switchable reflective color display pixel based on phase change material. This display pixel can switch between three different states under the stimulation of an electrical pulse, and selectively reflect red, green, and blue colors under an incandescent light source, respectively, thereby enabling the display of high-resolution color images under illumination.

[0035] To achieve the above objectives, the present invention provides an electrically controlled, in-situ switchable reflective color display pixel based on a phase change material. This display pixel can freely select to reflect red, green, or blue light under the stimulation of an electrical pulse. The display pixel has a multilayer film structure, consisting of, from bottom to top, a first metal reflective layer, a first transparent conductive dielectric layer, a first phase change material layer, a second transparent conductive dielectric layer, a second phase change material layer, a third transparent conductive dielectric layer, a second metal layer, and a fourth transparent conductive dielectric layer.

[0036] This invention provides an electrically controlled, in-situ switchable reflective color display pixel based on phase change materials. Its color selectivity is achieved through a bottom metal electrode forming a reflective layer, a top metal electrode forming a semi-transparent reflective mirror, and a middle transparent conductive layer and phase change material layer acting as a dielectric material, forming a typical Fabry-Perot resonant cavity. When light passes through the top metal electrode layer and enters the Fabry-Perot resonant cavity, it is reflected back and forth between the bottom metal reflective layer and the top semi-transparent reflective layer. The Fabry-Perot resonant cavity only allows light of specific wavelengths that are integer multiples of the cavity's optical thickness to pass through, thus achieving color selectivity. Furthermore, by changing the optical parameters resulting from switching the phase change material layer between crystalline and amorphous states, the optical thickness of the Fabry-Perot resonant cavity is altered, thereby switching between selectively reflecting red, green, or blue light.

[0037] The aforementioned electrically controllable, in-situ switchable reflective color display pixels are all homogeneous pixels, square in shape and arranged according to row and column rules. The bottom metallic reflective layer is connected to a single line (BL), and the top transparent conductive layer is connected to a single line (WL). When an electrical pulse is applied to the pixel, it heats the phase change material layer within the pixel. By applying electrical pulses of different intensities, the two phase change material layers can be crystallized sequentially, resulting in three states: amorphous-amorphous, amorphous-crystalline, and crystalline-crystalline.

[0038] In the embodiments, the sulfur-based phase change material is made of germanium tellurium, antimony tellurium, germanium antimony tellurium, germanium antimony selenium tellurium, antimony sulfur, or antimony selenium alloy material, and the thickness of the sulfur-based phase change material layer is 50nm-120nm.

[0039] In the embodiments, the transparent conductive dielectric material is made of indium tin oxide or aluminum-doped zinc oxide, and the thickness of the transparent conductive dielectric layer is 20nm-200nm.

[0040] In this embodiment, the metal electrode material is made of silver, platinum or titanium, and the thickness of the metal electrode layer is 5nm-150nm.

[0041] like Figure 1 As shown, the pixel arrangement of the electrically controlled, in-situ switchable reflective color display pixel based on phase change material provided by the present invention can follow the standard red-green-blue arrangement, but unlike traditional display devices which consist of three red, green, and blue sub-pixels forming a display pixel, the present invention does not have sub-pixels, but rather each display pixel can selectively display red, green, and blue light.

[0042] In this embodiment, as Figure 2As shown, all display pixels are homogeneous pixels and are multilayer film structures. From bottom to top, they are: a substrate layer, a first metal electrode, a first transparent conductive dielectric layer, a first chalcogenide phase change material layer, a second transparent conductive dielectric layer, a second chalcogenide phase change material layer, a third transparent conductive dielectric layer, a second metal electrode, and a fourth transparent conductive dielectric layer, which together constitute a Fabry-Perot resonant cavity, capable of exhibiting three different states under electrical pulses: amorphous-amorphous, amorphous-crystalline, and crystalline-crystalline. Figure 3 and Figure 4 As shown, these correspond to the selective reflection of blue, red, and green light under an incandescent lamp light source, respectively. Here, 'a' represents the amorphous state and 'c' represents the crystalline state. The pixel structure provided by this invention can achieve the color display function that traditional display devices require multiple pixels to achieve within a single pixel.

[0043] Preferably, in this embodiment, the metal electrode can be made of platinum, titanium or silver, the transparent conductive dielectric layer can be made of indium tin oxide or aluminum-doped zinc oxide, and the sulfide phase change material layer can be made of germanium tellurium, germanium antimony tellurium, antimony sulfide or antimony selenium alloy.

[0044] Specifically, the working principle of an electrically controlled, in-situ switchable reflective color display pixel based on phase change materials in this embodiment is as follows: a reflective layer is formed by a bottom metal electrode, a semi-transparent reflective mirror is formed by a top metal electrode, and a transparent conductive layer and a phase change material layer in the middle serve as the dielectric material, forming a typical Fabry-Perot resonant cavity. After light passes through the top metal electrode layer and enters the Fabry-Perot resonant cavity, it will be reflected back and forth between the bottom metal reflective layer and the top semi-transparent reflective layer. The Fabry-Perot resonant cavity only allows light of a specific wavelength that is an integer multiple of the optical thickness of the resonant cavity (the product of the film refractive index and the physical thickness) to pass through, thus exhibiting color selectivity. Therefore, the desired color selectivity can be achieved by adjusting the optical thickness of the Fabry-Perot resonant cavity. Here, we utilize the characteristic that phase change materials have different refractive indices before and after the phase change, i.e., the optical thickness can be changed without changing the film thickness, to design a Fabry-Perot resonant cavity with a double-layer phase change material.

[0045] Preferably, the first phase change material layer is GeTe, and the second phase change material layer is Sb2S3. When both phase change materials are amorphous, the multilayer film can selectively reflect blue light; when GeTe is crystalline and Sb2S3 is amorphous, the multilayer film can selectively reflect red light; and when both GeTe and Sb2S3 are crystalline, the multilayer film can selectively reflect green light.

[0046] It should be noted that those skilled in the art can also select other formulations and ratios of phase change materials to realize phase change material layers based on existing technologies, so as to achieve selective reflection of different colors of light. The above examples do not constitute a specific limitation on the scope of protection of this invention.

[0047] Preferably, in this embodiment, the thickness of the bottom metal electrode of an electrically controllable, in-situ switchable reflective color display pixel based on phase change material is 100nm-150nm, the thickness of the transparent conductive dielectric layer is 50nm-200nm, the thickness of the phase change material layer is 70nm-120nm, and the thickness of the top metal electrode is 5nm-20nm.

[0048] This embodiment provides an electrically controlled, in-situ switchable reflective color display pixel based on phase change material. This pixel can selectively reflect any color (red, green, or blue) in a single pixel, displaying a clear image with high resolution under sufficient light conditions, and also features eye protection.

[0049] The following detailed description, in conjunction with specific embodiments, illustrates an electrically controlled, in-situ switchable reflective color display pixel based on phase change material provided by the present invention.

[0050] Example 1

[0051] In this embodiment 1, an electrically controlled, in-situ switchable reflective color display pixel based on phase change material is provided. All pixels are homogeneous pixels. The film structure from bottom to top is Ag / ITO / GeTe / ITO / Sb2S3 / ITO / Ag / ITO, where the thickness of ITO is 20nm-200nm and the thickness of the phase change material layer is 70-120nm.

[0052] The specific design of an electrically controllable, in-situ switchable reflective color display pixel based on phase change material in this embodiment 1 is as follows: (1) The metal reflective layer is selected as Ag material, the transparent conductive dielectric material is selected as ITO, the first phase change material is selected as GeTe, and the second phase change material is selected as Sb2S3; (2) The thickness of the bottom metal reflective layer of the multilayer film is 135nm, the bottom ITO layer is 75nm, the first phase change material layer is 96nm, the middle ITO layer is 163nm, the second phase change material layer is 92nm, the upper ITO layer is 76nm, the top metal layer is 8nm, and the top ITO layer is 39nm; (3) When both phase change materials are amorphous, the reflected color is blue. When the first phase change material is crystalline and the second phase change material is amorphous, the corresponding color is red. When both phase change material layers are crystalline, the corresponding color is green. The above phase transition can be achieved by applying an electrical pulse. As shown in the figure, the simulation results demonstrate that the electrically controlled, in-situ switchable reflective color display pixel based on phase change material provided in this embodiment can freely switch between selectively reflecting red, green, and blue colors.

[0053] The reflectivity data in this embodiment was obtained through simulation software calculation. For example... Figure 5 The figure shows the refractive index (n) and extinction coefficient (k) of materials Ag, ITO, GeTe, and Sb₂S₃ in the visible light band of 400nm-700nm. After importing the optical parameters of these materials into simulation software, a multilayer film structure can be constructed. In this embodiment, SiO₂ is selected as the substrate layer during simulation. After obtaining the reflectivity data from the simulation, the data is imported into the Chromaticity Diagram in OriginLab software and processed into a CIE chromaticity diagram. The Spectral Power Distribution of Illuminant is selected as A, meaning the light source is a tungsten filament incandescent lamp.

[0054] It should be understood that expressions such as “comprising” and “may include” used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as “comprising” and / or “having” are to be interpreted as indicating a particular characteristic, number, operation, constituent element, component, or combination thereof, but not to exclude the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0055] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A pixel structure, characterized in that, From bottom to top, it includes: a first metal layer, a first transparent conductive dielectric layer, a first phase change material layer, a second transparent conductive dielectric layer, a second phase change material layer, a third transparent conductive dielectric layer, a second metal layer, and a fourth transparent conductive dielectric layer; The thickness of the first metal layer is within a first preset thickness range, making the first metal layer a total reflective layer; The thickness of the second metal layer is within a second preset thickness range, making the second metal layer a semi-transparent reflective layer; The first transparent conductive dielectric layer, the first phase change material layer, the second transparent conductive dielectric layer, the second phase change material layer, the third transparent conductive dielectric layer, and the fourth transparent conductive dielectric layer serve as dielectric materials, forming a Fabry-Perot resonant cavity with the first metal layer and the second metal layer; When the physical thickness of the Fabry-Perot resonant cavity is at a third preset thickness, the pixel structure can selectively reflect different colors of light when the crystallization state of either the first phase change material layer or the second phase change material layer changes.

2. The pixel structure according to claim 1, characterized in that, The third preset thickness multiplied by the refractive index of the pixel structure is equal to an integer multiple of the wavelength of light to be selectively reflected by the pixel structure; wherein, the refractive index of the pixel structure varies with the crystallization state of the first phase change material layer and the second phase change material layer.

3. The pixel structure according to claim 1 or 2, characterized in that, The first preset thickness range is 100nm-150nm; The second preset thickness range is 5nm-20nm.

4. The pixel structure according to claim 1 or 2, characterized in that, The thickness of both phase change material layers is within the range of 70nm-120nm; The thickness of the four transparent conductive dielectric layers mentioned above is all within the range of 50nm-200nm.

5. The pixel structure according to claim 1 or 2, characterized in that, The two phase change material layers mentioned above are made of sulfur-based phase change materials.

6. The pixel structure according to claim 1 or 2, characterized in that, The four transparent conductive dielectric layers mentioned above are made of indium tin oxide or aluminum-doped zinc oxide.

7. The pixel structure according to claim 1, characterized in that, When the physical thickness of the Fabry-Perot resonant cavity is at a third preset thickness, and the first phase change material layer is GeTe material and the second phase change material layer is Sb2S3 material, if both the first and second phase change material layers are in an amorphous state, the pixel structure can selectively reflect blue light; if both the first and second phase change material layers are in a crystalline state, the pixel structure can selectively reflect green light; and if the first phase change material layer is in a crystalline state and the second phase change material layer is in an amorphous state, the pixel structure can selectively reflect red light.

8. A display driving method for the pixel structure according to any one of claims 1 to 7, characterized in that, Includes the following steps: Applying electrical pulses of different intensities to the pixel structure causes the first phase change material layer and the second phase change material layer to crystallize separately, thereby controlling the crystallization state of the two phase change material layers in the pixel structure and enabling the pixel structure to selectively reflect light of different colors.

Images