Cholesterol liquid crystal display device, array substrate thereof and substrate manufacturing method

Abstract

The invention discloses a cholesterol liquid crystal display device, an array substrate thereof and a substrate manufacturing method, aiming at an active cholesterol liquid crystal display device, reflection of an insulating layer to incident light is effectively reduced by reducing the thickness of the insulating layer in a displayed opening area, so that the incident light is irradiated on cholesterol liquid crystal as much as possible, and the display effect is improved. Therefore, the display effect of the liquid crystal screen is improved. Meanwhile, by optimizing the manufacturing method of the substrate, the thinning of the insulating layer in the opening region is realized while the characteristics of the TFT in the device region are ensured, so that the influence of the thinning of the insulating layer on the manufacturing process steps is reduced as much as possible.

Description

Technical Field

[0001] This invention relates to the field of cholesterol liquid crystal display technology, and more particularly to a cholesterol liquid crystal display device, its array substrate, and a method for manufacturing the substrate. Background Technology

[0002] Cholesterol liquid crystal is one of the main technologies used in reflective displays. Due to the bistable display characteristic of its liquid crystal molecules, it offers excellent power savings. The bistable characteristic of cholesterol liquid crystal molecules means that they exist in two stable states: a planar state and a focal-conic state. In the planar state, the liquid crystals are neatly aligned and can reflect light of a specific wavelength; this is usually called the bright state. In the focal-conic state, the liquid crystals are randomly aligned, and incident light is either transmitted or scattered, with very little reflection; this is usually called the dark state. When a voltage is applied, the alignment state of the cholesterol liquid crystal molecules can be controlled to switch between these two stable states. Power is only required during state transitions (from the planar state to the focal-conic state, or vice versa). When the screen is still, almost no power is used, resulting in excellent power savings. Furthermore, because it is a reflective display, it does not require a backlight, resulting in lower brightness and better protection of the eyes from strong light.

[0003] Currently available active-matrix (AM) color cholesteric liquid crystal panels consist of liquid crystal cells filled with red, green, and red pigments stacked on top of each other. Light shines from the top sixth substrate, and the colors are formed by reflections from the red, green, and red liquid crystal cells. In actual installations, multilayer RGB liquid crystal panels are typically designed with blue, green, and red liquid crystal cells from top to bottom based on the wavelengths of RGB light. Figure 1 As shown, in this situation, ambient light shines downwards onto the bottom red LCD panel, resulting in minimal light intensity. Consequently, the white image displayed on the panel appears bluish. The brightness (light reflectivity) of the red image is lower than the other two colors. Therefore, for reflective cholesteric LCD panels, it is necessary to minimize the impact of the display area on transmitted light. Summary of the Invention

[0004] To address the technical problems existing in the background art, the present invention proposes a cholesterol liquid crystal display device, its array substrate, and a method for manufacturing the substrate.

[0005] The present invention provides an array substrate for a cholesterol liquid crystal display device, comprising: a substrate body; The substrate body is provided with a pixel array formed by multiple pixel units, each pixel unit including a device area and an opening area; A TFT device is provided on the device area. The TFT device includes a gate, a first insulating portion, a semiconductor structure, a source, and a second insulating portion disposed on the substrate body. The first insulating portion covers the gate. The semiconductor structure is located above the first insulating portion and has a channel structure corresponding to the gate. The source is disposed above the semiconductor structure and has a slot corresponding to the channel. The second insulating portion is located above the source. A pixel electrode is provided in the opening area. The pixel electrode includes a third insulating portion and an electrode portion disposed sequentially from bottom to top on the substrate body. The thickness of the third insulating portion is less than that of the first insulating portion.

[0006] Preferably, the thickness d of the third insulating part is calculated by the following equation; nd = 1 / 4λ; Where n is the refractive index of the third insulating part, and λ is the wavelength of the incident light.

[0007] Preferably, the third insulating part and the first insulating part form an integral structure.

[0008] Preferably, the first insulating part is made of silicon dioxide material, and the second insulating part is made of organic resin material.

[0009] Preferably, the opening area is further provided with a fourth insulating layer and an electrode connection structure. The electrode connection structure is located above the third insulating layer and connected to the source layer. The fourth insulating layer is located above the electrode connection structure, and the pixel electrode layer is located above the fourth insulating layer.

[0010] The present invention also proposes a cholesterol liquid crystal display device, comprising a common substrate, an array substrate of the aforementioned cholesterol liquid crystal display device, and a cholesterol liquid crystal layer sandwiched between the two, wherein the common substrate is provided with common electrodes arranged corresponding to the pixel electrodes.

[0011] The present invention also proposes a method for manufacturing a substrate for the above-mentioned cholesterol liquid crystal display device, comprising the following steps: S1. A first metal film is formed on the substrate body, and the first metal film is processed to form a gate in the device region. S2. Form a first insulating film layer, process the first insulating film layer to form a first insulating portion in the device region and form a third insulating portion in the opening region, wherein the first insulating portion is located above the gate. S3. A semiconductor structure is formed above the first insulating portion; S4. A second metal film is formed above the semiconductor structure, and the second metal film is processed to form a source in the device region; S5. Form a second insulating film layer, process the second insulating film layer to form a second insulating portion in the device region, the second insulating portion being located above the source electrode; S6. An ITO electrode film layer is formed in the opening area.

[0012] Preferably, in S2, the process of processing the first insulating film layer to form a first insulating portion in the device region and a third insulating portion in the opening region specifically involves exposing the first insulating film layer using Halftone Mask technology to form the first insulating portion and the third insulating portion, and reducing the thickness of the third insulating portion to a preset thickness.

[0013] Preferably, in S5, the process of treating the second insulating film layer to form a second insulating portion in the device region specifically involves removing the fourth insulating layer in the opening region.

[0014] This invention proposes a cholesteric liquid crystal display device, its array substrate, and a substrate fabrication method. Specifically for active-matrix cholesteric liquid crystal displays, this invention effectively reduces the reflection of incident light by the insulating layer at the display aperture region by thinning the layer, allowing as much light as possible to irradiate the cholesteric liquid crystal, thereby improving the display effect of the liquid crystal screen. Simultaneously, by optimizing the substrate fabrication method, the characteristics of the TFT in the device region are maintained while the insulating layer in the aperture region is thinned, thus minimizing the impact of insulating layer thinning on the fabrication process steps. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a multilayer liquid crystal cell structure in one embodiment of a cholesterol liquid crystal display device proposed in this invention.

[0016] Figure 2 This is a schematic diagram of one embodiment of the array substrate of a cholesterol liquid crystal display device proposed in this invention.

[0017] Figure 3 This is a schematic diagram of one embodiment of a cholesterol liquid crystal display device proposed in this invention.

[0018] Figure 4 This is a flowchart illustrating one embodiment of a method for fabricating a substrate for a cholesterol liquid crystal display device according to the present invention. Detailed Implementation

[0019] Reference Figure 2 and 3 The present invention proposes an array substrate for a cholesterol liquid crystal display device, characterized in that it comprises: a substrate body 1; The substrate body 1 is provided with a pixel array formed by multiple pixel units, each pixel unit including a device area and an opening area; A TFT device 2 is provided on the device area. The TFT device 2 includes a gate 21, a first insulating portion 22, a semiconductor structure 23, a source 24, and a second insulating portion 25 disposed on the substrate body 1. The first insulating portion 22 covers the gate 21. The semiconductor structure 23 is located above the first insulating portion 22 and has a channel structure corresponding to the gate 21. The source 24 is disposed above the semiconductor structure 23 and has a slot corresponding to the channel. The second insulating portion 25 is located above the source 24. A pixel electrode 3 is provided in the opening area. The pixel electrode 3 includes a third insulating portion 31 and an electrode portion 32 disposed sequentially from bottom to top on the substrate body 1. The thickness of the third insulating portion 31 is less than that of the first insulating portion 22.

[0020] To explain in detail the operation of the array substrate in this embodiment, this embodiment also proposes a cholesteric liquid crystal display device, including a common substrate 20, the array substrate of the cholesteric liquid crystal display device described above, and a cholesteric liquid crystal layer 30 sandwiched between the two. The common substrate 20 is provided with a common electrode 40 arranged corresponding to the pixel electrode 3.

[0021] During display, when the cholesteric liquid crystal is in a planar alignment, it reflects light of a specific wavelength; conversely, when it is in a focal conical alignment, light passes through. Therefore, by applying a voltage to the cholesteric liquid crystal, it can be controlled whether light passes through or reflects a specific wavelength. During display, the pixel electrodes and common electrode on both sides of each pixel unit are controlled. An appropriate voltage is applied to the cholesteric liquid crystal layer, causing the cholesteric liquid crystal molecules within the layer to rotate, thereby controlling the state of the liquid crystal molecules and switching between incident light reflection and transmission. In an active cholesteric liquid crystal display device, each pixel electrode is connected to a TFT device. The TFT device switches to control the operation of the corresponding pixel electrode, thus switching the state of the liquid crystal molecules in the pixel unit.

[0022] To improve the light utilization rate of the pixel unit aperture area, the thickness of the insulating layer in the aperture area is reduced, thereby reducing the effect of the aperture material on light refraction and thus increasing the transmission light. In this embodiment, the proposed cholesteric liquid crystal display device and its array substrate, specifically for an active cholesteric liquid crystal display device, effectively reduces the reflection of incident light by the insulating layer at the aperture area of ​​the display by reducing the thickness of the insulating layer, allowing as much light as possible to irradiate the cholesteric liquid crystal, thereby improving the display effect of the liquid crystal screen.

[0023] In the specific design of the third insulating part, the thickness d of the third insulating part 31 is calculated by the following equation; nd = 1 / 4λ; Where n is the refractive index of the third insulating part 31, and λ is the wavelength of the incident light.

[0024] When the thickness of the insulating layer satisfies that the optical path difference is 1 / 4 of the incident light wavelength, i.e., the optical thickness: nd = 1 / 4λ, the incident light will generate a phase difference when reflected from the upper and lower surfaces of the film, causing the two reflected beams to interfere and cancel each other out, thereby canceling the reflected light and increasing the transmitted light, thus further improving the utilization rate of ambient light.

[0025] Reference Figure 4 This embodiment also proposes a method for fabricating the array substrate of the above-mentioned cholesterol liquid crystal display device, comprising the following steps: S1. A first metal film is formed on the substrate body 1, and the first metal film is processed to form a gate 21 in the device region.

[0026] S2. A first insulating film layer is formed. The first insulating film layer is processed to form a first insulating portion 22 in the device region and a third insulating portion 31 in the opening region. The first insulating portion 22 is located above the gate 21. The third insulating portion 31 and the first insulating portion 22 form an integral structure through the first insulating film layer. Preferably, the first insulating portion 22 is made of silicon dioxide material.

[0027] Specifically, the process of processing the first insulating film layer to form a first insulating portion 22 in the device region and a third insulating portion 31 in the opening region involves exposing the first insulating film layer using Halftone Mask technology to form the first insulating portion 22 and the third insulating portion 31, and reducing the thickness of the third insulating portion 31 to a preset thickness.

[0028] Halftone masking technology utilizes the partial light transmittance of a grating to partially expose the photoresist (PR). It uses a grating as the photomask. Currently, the fabrication of array substrates in TFT-LCDs typically involves five mask exposures and etching processes: 1. G-mask exposure to form the gate-related patterns; 2. I-mask exposure to form the island patterns for the channels; 3. D-mask exposure to form the data line-related patterns; 4. C-mask exposure to form the contact hole patterns; 5. PI-mask exposure to form the pixel electrodes. This process is numerous and complex. By employing halftone masking technology, the I and D processes are combined into a single process, reducing the original five processes to four exposure and etching processes to form the desired patterns. The specific principle is as follows: Halftone Mask is used for exposure. The purpose is to maintain the thickness and pattern of the insulating film layer at the TFT so that the characteristics of the TFT remain unchanged. At the same time, the thickness of the film layer in the pixel opening area should reach an ideal value to create an opening in the passivation layer that connects with the surrounding pads. Then, the photoresist is ashing to expose the pixel part that forms the ITO pattern. After the ITO film is formed, the photoresist is peeled off using a stripping method to remove the unwanted ITO layer.

[0029] In this embodiment, during the formation of the first insulating film layer, a Halftone Mask is used for exposure to form a first insulating portion located in the device region according to preset requirements. This can maintain the thickness and pattern of the insulating film layer at the TFT device and keep the characteristics of the TFT unchanged. At the same time, the formation of the second insulating portion located in the opening region should also ensure that the thickness of the third insulating portion in the pixel opening region reaches an ideal value.

[0030] S3. A semiconductor structure 23 is formed above the first insulating portion 22.

[0031] S4. A second metal film is formed above the semiconductor structure 23, and the second metal film is processed to form a source electrode 24 in the device region.

[0032] S5. A second insulating film layer is formed. The second insulating film layer is processed to form a second insulating portion 25 in the device region. The second insulating portion 25 is located above the source electrode 24. Specifically, the second insulating portion 25 is made of an organic resin material.

[0033] To further reduce the impact of the insulating layer on the optical path of the opening area, the insulating film layer of the opening area can be removed during the processing.

[0034] S6. An ITO electrode film layer is formed in the opening area.

[0035] In the specific connection method between the ITO electrode film layer in the opening region and the source electrode in the device region, a fourth insulating layer 4 and an electrode connection structure 5 are also provided on the opening region. The electrode connection structure 5 is located above the third insulating layer and connected to the source electrode layer 24. The fourth insulating layer 4 is located above the electrode connection structure 5, and the pixel electrode layer 3 is located above the fourth insulating layer 4. The electrode connection structure can extend a portion of electrical connection in the opening region through the source electrode, and then the fourth insulating layer covers the electrical connection portion and forms a hole thereon. Then, during the formation of the ITO electrode film layer, the electrode and the electrical connection portion are connected through the hole.

[0036] In this embodiment, the proposed substrate fabrication method for a cholesterol liquid crystal display device optimizes the substrate fabrication method, ensuring the characteristics of the TFT in the device region while reducing the thickness of the insulating layer in the opening region, thereby minimizing the impact of insulating layer thinning on the fabrication process steps.

[0037] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An array substrate for a cholesterol liquid crystal display device, characterized in that, include: Substrate body (1); The substrate body (1) is provided with a pixel array formed by multiple pixel units, each pixel unit including a device area and an opening area; The device area is provided with a TFT device (2), the TFT device (2) includes a gate (21), a first insulating portion (22), a semiconductor structure (23), a source (24) and a second insulating portion (25) disposed on the substrate body (1). The first insulating portion (22) covers the gate (21). The semiconductor structure (23) is located above the first insulating portion (22) and has a channel structure corresponding to the gate (21). The source (24) is disposed above the semiconductor structure (23) and has a slot corresponding to the channel. The second insulating portion (25) is located above the source (24). The opening area is provided with a pixel electrode (3). The pixel electrode (3) includes a third insulating portion (31) and an electrode portion (32) disposed sequentially from bottom to top on the substrate body (1). The thickness of the third insulating portion (31) is less than that of the first insulating portion (22).

2. The array substrate of the cholesterol liquid crystal display device according to claim 1, characterized in that, The thickness d of the third insulating part (31) is calculated by the following equation; nd = 1 / 4λ; Where n is the refractive index of the third insulating part (31) and λ is the wavelength of the incident light.

3. The array substrate of the cholesterol liquid crystal display device according to claim 1, characterized in that, The third insulating part (31) and the first insulating part (22) form an integral structure.

4. The array substrate of the cholesterol liquid crystal display device according to claim 1 or 3, characterized in that, The first insulating part (22) is made of silicon dioxide material, and the second insulating part (25) is made of organic resin material.

5. The array substrate of the cholesterol liquid crystal display device according to claim 1, characterized in that, The opening area is also provided with a fourth insulating layer (4) and an electrode connection structure (5). The electrode connection structure (5) is located above the third insulating layer and connected to the source electrode (24) layer. The fourth insulating layer (4) is located above the electrode connection structure (5), and the pixel electrode (3) layer is located above the fourth insulating layer (4).

6. A cholesterol liquid crystal display device, characterized in that, The device includes a common substrate (20), an array substrate of the cholesterol liquid crystal display device according to any one of claims 1-5, and a cholesterol liquid crystal layer (30) sandwiched between the two. The common substrate (20) is provided with a common electrode (40) arranged corresponding to the pixel electrode (3).

7. A method for fabricating a substrate for an array substrate of a cholesteric liquid crystal display device according to any one of claims 1-5, characterized in that, Includes the following steps: S1. A first metal film is formed on the substrate body (1), and the first metal film is processed to form a gate (21) in the device region. S2. Form a first insulating film layer, process the first insulating film layer to form a first insulating portion (22) in the device region and form a third insulating portion (31) in the opening region, wherein the first insulating portion (22) is located above the gate (21); S3. A semiconductor structure (23) is formed above the first insulating portion (22); S4. A second metal film is formed above the semiconductor structure (23), and the second metal film is processed to form a source electrode (24) in the device region. S5. Form a second insulating film layer and process the second insulating film layer to form a second insulating part (25) in the device region. The second insulating part (25) is located above the source electrode (24). S6. An ITO electrode film layer is formed in the opening area.

8. The method for manufacturing a substrate for a cholesterol liquid crystal display device according to claim 7, characterized in that, In S2, the first insulating film layer is processed to form a first insulating portion (22) in the device region and a third insulating portion (31) in the opening region. Specifically, the first insulating film layer is exposed by Halftone Mask technology to form the first insulating portion (22) and the third insulating portion (31), and the thickness of the third insulating portion (31) is reduced to a preset thickness.

9. The method for manufacturing a substrate for a cholesterol liquid crystal display device according to claim 7, characterized in that, In S5, the process of treating the second insulating film layer to form a second insulating portion (25) in the device region specifically involves removing the insulating film layer in the opening region.

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