Reflective display screen

Abstract

A reflective display screen comprises a first substrate, a second substrate and a first cholesteric liquid crystal layer, the first cholesteric liquid crystal layer comprising first cholesteric liquid crystals reflecting blue light; the reflective display screen further comprises a third substrate, a fourth substrate and a second cholesteric liquid crystal layer; the reflective display screen is provided with a plurality of pixel areas, the plurality of pixel areas comprising a plurality of first pixel areas emitting red light and a plurality of second pixel areas emitting green light, the second cholesteric liquid crystal layer comprising second cholesteric liquid crystals reflecting red light and third cholesteric liquid crystals reflecting green light, the second cholesteric liquid crystals being located in each first pixel area correspondingly, and the third cholesteric liquid crystals being located in each second pixel area correspondingly. The reflective display screen of the present application displays images by using external ambient light, so that the reflective display screen does not need to be provided with a backlight source, the overall thickness of the display screen is reduced, and the structure is simple.

Description

Technical Field

[0001] This invention relates to the field of liquid crystal display technology, and in particular to a reflective display screen. Background Technology

[0002] Liquid crystal displays (LCDs) have advantages such as good image quality, small size, light weight, low driving voltage, low power consumption, no radiation, and relatively low manufacturing cost, and they dominate the flat panel display field.

[0003] Cholesteric liquid crystal bistable displays (CLLs) are reflective displays that utilize ambient light to display images, eliminating the need for a backlight. The key feature of CLL technology is the presence of two texture states: a planar texture (p-state) and a focal conic texture (fc-state), both of which remain stable in the absence of an external electric field. In the p-state, if the wavelength of the incident light matches the pitch, the light is reflected as circularly polarized light. In the fc-state, the pitch distribution is random, resulting in light scattering. Under the influence of an external electric field, these two states can switch between each other, exhibiting bistable characteristics. Because the two texture states used in the display are stable in the absence of an external field, there is no need to apply an external field for extended periods to maintain the display state; therefore, CLLs are energy-efficient.

[0004] For cholesteric liquid crystal bistable display technology, due to the requirements of liquid crystal pitch, a single-cell architecture can generally only perform monochrome or black-and-white displays. If color display is required, a three-layer liquid crystal cell architecture is needed. For example, Chinese Patent Publication No. CN109407437A provides a cholesteric liquid crystal display screen using a three-layer liquid crystal cell architecture.

[0005] In the prior art, cholesteric liquid crystal displays using a three-layer liquid crystal cell architecture are thicker and have poorer specifications due to the three-layer liquid crystal cell architecture. In addition, the manufacturing process is complex and costly due to the three-layer liquid crystal cell architecture. Moreover, the complex structure also results in poor stability. Summary of the Invention

[0006] The purpose of this invention is to provide a reflective display screen that uses ambient light to display images. Therefore, the reflective display screen does not require a backlight, which reduces the overall thickness of the display screen and simplifies the structure.

[0007] This invention provides a reflective display screen, including a first substrate, a second substrate disposed opposite to the first substrate, and a first cholesteric liquid crystal layer disposed between the first substrate and the second substrate. The first cholesteric liquid crystal layer includes a first cholesteric liquid crystal that reflects blue light. The reflective display screen also includes a third substrate disposed on the second substrate, a fourth substrate disposed opposite to the third substrate, and a second cholesteric liquid crystal layer disposed between the third substrate and the fourth substrate. The reflective display screen has a plurality of pixel regions, including a plurality of first pixel regions that emit red light and a plurality of second pixel regions that emit green light. The second cholesteric liquid crystal layer includes a second cholesteric liquid crystal that reflects red light and a third cholesteric liquid crystal that reflects green light. The second cholesteric liquid crystal is located in each of the first pixel regions, and the third cholesteric liquid crystal is located in each of the second pixel regions.

[0008] Furthermore, the first substrate is provided with a plurality of first pixel electrodes, each of which is spaced apart from each other; the third substrate is provided with a plurality of second pixel electrodes, each of which is spaced apart from each other, and each of the second pixel electrodes corresponds one-to-one with each pixel region; the number of the first pixel electrodes and the number of the second pixel electrodes are the same.

[0009] Furthermore, the plurality of pixel regions also include a plurality of third pixel regions that emit blue light, and the second cholesteric liquid crystal layer also includes a transparent layer, which is located in each of the third pixel regions.

[0010] This invention also provides a reflective display screen, including a first substrate, a second substrate disposed opposite to the first substrate, and a cholesteric liquid crystal layer disposed between the first substrate and the second substrate. The cholesteric liquid crystal layer is used to reflect blue light. The reflective display screen has a plurality of pixel regions, including a plurality of first pixel regions emitting red light, a plurality of second pixel regions emitting green light, and a plurality of third pixel regions emitting blue light. The second substrate has a photoluminescent layer on the side near the cholesteric liquid crystal layer. The photoluminescent layer includes a first quantum dot layer, a second quantum dot layer, and a first transparent layer. The first quantum dot layer is located in each of the first pixel regions, the second quantum dot layer is located in each of the second pixel regions, and the first transparent layer is located in each of the third pixel regions. The first quantum dot layer contains quantum dots that generate red light, and the second quantum dot layer contains quantum dots that generate green light.

[0011] Furthermore, the first substrate is provided with a plurality of pixel electrodes, each pixel electrode being spaced apart from each other, and each pixel electrode corresponding to each pixel region.

[0012] Furthermore, the pixel electrode is provided with a first protrusion structure, the second substrate is provided with a common electrode, and the common electrode is provided with a plurality of second protrusion structures, each of the second protrusion structures corresponding to each of the first protrusion structures.

[0013] Furthermore, the surface of the first protrusion structure is provided with a reflective layer, or the entire reflective layer is disposed on the pixel electrode.

[0014] Furthermore, a polarizer, which is a quarter-wave plate, is provided on the side of the second substrate away from the cholesteric liquid crystal layer.

[0015] Furthermore, the first substrate has a light-absorbing layer on the side near the cholesteric liquid crystal layer.

[0016] Furthermore, a black matrix and a color film layer are provided between the second substrate and the photoluminescent layer. The color film layer is separated by the black matrix and includes a red color resist layer, a green color resist layer and a second transparent layer. The red color resist layer is located in each first pixel area, the green color resist layer is located in each second pixel area and the second transparent layer is located in each third pixel area.

[0017] The reflective display screen provided in this embodiment of the invention uses ambient light to display images. Therefore, the reflective display screen does not require a backlight, which reduces the overall thickness of the display screen and simplifies the structure. Attached Figure Description

[0018] Figure 1 This is a cross-sectional view of the reflective display screen in the first embodiment of the present invention.

[0019] Figure 2 This is a cross-sectional view of the reflective display screen in the second embodiment of the present invention.

[0020] Figure 3 This is a cross-sectional view of the reflective display screen in the third embodiment of the present invention.

[0021] Figure 4 This is a cross-sectional view of the reflective display screen in the fourth embodiment of the present invention.

[0022] Figure 5 This is a cross-sectional view of the reflective display screen in the fifth embodiment of the present invention. Detailed Implementation

[0023] To further illustrate the technical methods and effects of the present invention in order to achieve the intended purpose, the specific implementation methods, structure, features and effects of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0024] [First Embodiment]

[0025] like Figure 1 As shown, the reflective display screen provided in the first embodiment of the present invention includes a first substrate 11, a second substrate 12 disposed opposite to the first substrate 11, and a first cholesteric liquid crystal layer 13 disposed between the first substrate 11 and the second substrate 12. The first cholesteric liquid crystal layer 13 includes a first cholesteric liquid crystal 131 that reflects blue light. The reflective display screen also includes a third substrate 21 disposed on the second substrate 12, a fourth substrate 22 disposed opposite to the third substrate 21, and a second cholesteric liquid crystal layer 23 disposed between the third substrate 21 and the fourth substrate 22. That is, from bottom to top, the components are the first substrate 11, the first cholesteric liquid crystal layer 13, the second substrate 12, the third substrate 21, the second cholesteric liquid crystal layer 23, and the fourth substrate 22.

[0026] The reflective display screen has multiple pixel regions, including multiple first pixel regions 1a that emit red light and multiple second pixel regions 1b that emit green light. The second cholesteric liquid crystal layer 23 includes a second cholesteric liquid crystal 231 that reflects red light and a third cholesteric liquid crystal 232 that reflects green light. The second cholesteric liquid crystal 231 is located in each of the first pixel regions 1a, and the third cholesteric liquid crystal 232 is located in each of the second pixel regions 1b.

[0027] Specifically, cholesteric liquid crystals possess two stable states: a planar texture (p-state) and a focal conic texture (fc-state). When different electric fields are applied to the cholesteric liquid crystal, it can switch between these two textures. When the cholesteric liquid crystal exhibits a focal conic texture, light can pass through; when it exhibits a planar texture, it reflects light of a specific wavelength.

[0028] The wavelength of selectively reflected light by cholesteric liquid crystals is related to the pitch of the cholesteric liquid crystal. By changing the pitch of the cholesteric liquid crystal, the wavelength of reflected light can be controlled. For example, by adding a chiral agent to the cholesteric liquid crystal and adjusting the concentration of the chiral agent, a first cholesteric liquid crystal 131 reflecting blue light (wavelength 435 nm to 450 nm), a second cholesteric liquid crystal 231 reflecting red light (wavelength 622 nm to 760 nm), and a third cholesteric liquid crystal 232 reflecting green light (wavelength 492 nm to 577 nm) can be formulated. The chiral agent causes the cholesteric liquid crystal to rotate, thus twisting it in a specific direction. Chiral agents with different chiral directions can twist the cholesteric liquid crystal in different directions; specifically, they can cause the cholesteric liquid crystal to rotate left-handed or right-handed, thereby forming a helical structure with a preset pitch for reflecting light within a specific wavelength range. In a specific example, the reflected light wavelength of the first cholesteric liquid crystal 131 can be 448 nm, the reflected light wavelength of the second cholesteric liquid crystal 231 can be 630 nm, and the reflected light wavelength of the third cholesteric liquid crystal 232 can be 532 nm.

[0029] In this embodiment, the second cholesteric liquid crystal 231 and the third cholesteric liquid crystal 232 are spaced apart by a barrier 234. The barrier 234 is disposed at the boundary between two adjacent pixel regions.

[0030] Furthermore, the first substrate 11 is provided with multiple scan lines and multiple data lines, which intersect to form multiple control units arranged in a matrix. The first substrate 11 is also provided with multiple first pixel electrodes 14, which are spaced apart from each other. Each first pixel electrode 14 is connected to a corresponding scan line and data line through a thin-film transistor. A first common electrode 15 (shown on one side of the second substrate 12) is provided on either the first substrate 11 or the second substrate 12. By applying a control voltage to the first pixel electrodes 14 and the first common electrode, the first cholesteric liquid crystal 131 within the corresponding control unit can be controlled to switch between a planar texture and a focal conic texture, thereby causing the first cholesteric liquid crystal 131 to reflect blue light or transmit light through it.

[0031] Similarly, the third substrate 21 is also provided with multiple scan lines and multiple data lines, which intersect to define the aforementioned multiple pixel regions arranged in a matrix. The third substrate 21 is also provided with multiple second pixel electrodes 24, each second pixel electrode 24 is spaced apart from each other, and each second pixel electrode 24 corresponds one-to-one with each pixel region. Each pixel region has one second pixel electrode 24, and each second pixel electrode 24 is connected to the corresponding scan line and data line through a thin film transistor. The third substrate 21 or the fourth substrate 22 is provided with a second common electrode 25 (shown on one side of the fourth substrate 22 in the figure). By applying a control voltage to the second pixel electrode 24 and the second common electrode, the second cholesteric liquid crystal 231 and the third cholesteric liquid crystal 232 corresponding to the pixel region can be controlled to switch between planar texture and focal conic texture, thereby causing the second cholesteric liquid crystal 231 to reflect red light or transmit light through the second cholesteric liquid crystal 231, and causing the third cholesteric liquid crystal 232 to reflect green light or transmit light through the third cholesteric liquid crystal 232.

[0032] Furthermore, the number of the first pixel electrode 14 and the second pixel electrode 24 are the same, and the first pixel electrode 14 can be disposed directly below the second pixel electrode 24 or offset from the second pixel electrode 24.

[0033] Furthermore, a first alignment film 16 is provided on the side of the first substrate 11 and the second substrate 12 near the first cholesteric liquid crystal layer 13, and a second alignment film 26 is provided on the side of the third substrate 21 and the fourth substrate 22 near the second cholesteric liquid crystal layer 23.

[0034] In this embodiment, a first cholesteric liquid crystal 131 reflecting blue light is independently disposed between the first substrate 11 and the second substrate 12. A second cholesteric liquid crystal 231 reflecting red light and a third cholesteric liquid crystal 232 reflecting green light are disposed between the third substrate 21 and the fourth substrate 22 and overlapped with the first cholesteric liquid crystal 131. Each display pixel includes one red sub-pixel, one green sub-pixel and two blue sub-pixels. When natural light (shown by the hollow arrow in the figure) is incident on the reflective display screen, part of the light is reflected by the second cholesteric liquid crystal 231 and the third cholesteric liquid crystal 232 to display the required red and green light. The unreflected light continues to be incident on the first cholesteric liquid crystal 131 and is reflected by the first cholesteric liquid crystal 131 to emit the required blue light.

[0035] The reflective display screen in this embodiment uses ambient light to display images, thus eliminating the need for a backlight, reducing the overall thickness of the display screen, and simplifying its structure. Furthermore, this embodiment employs a dual-layer liquid crystal cell architecture, resulting in a thinner overall display screen, simpler manufacturing process, and lower production costs.

[0036] Furthermore, in color displays, a pixel typically consists of three sub-pixels: red (R), green (G), and blue (B). In this embodiment, the reflective display screen adds a blue sub-pixel to each display pixel, and the red (R), green (G), and blue (B) sub-pixels are composed of two separate liquid crystal cells. The color display effect of the dual-layer liquid crystal cell structure can be adjusted by separately adjusting the first cholesteric liquid crystal layer 13 or the second cholesteric liquid crystal layer 23. Compared to existing technologies, this improves the display effect, reduces adjustment difficulty, and facilitates operation.

[0037] [Second Embodiment]

[0038] like Figure 2 As shown, the difference between the reflective display screen of this embodiment and the first embodiment is that: the multiple pixel areas also include multiple third pixel areas 1c that emit blue light, and the second cholesteric liquid crystal layer 23 also includes a transparent layer 233, which is located in each of the third pixel areas 1c.

[0039] Other structures of the reflective display screen in this embodiment can be referred to in the first embodiment described above, and will not be repeated here.

[0040] In this embodiment, each display pixel of the reflective display screen includes one red sub-pixel, one green sub-pixel, and three blue sub-pixels. When natural light (as shown by the hollow arrow in the figure) is incident on the reflective display screen, a portion of the light is reflected by the second cholesteric liquid crystal 231 and the third cholesteric liquid crystal 232 to display the required red and green light. The unreflected light continues to be incident on the first cholesteric liquid crystal 131, and the required blue light is reflected by the first cholesteric liquid crystal 131. The three blue sub-pixels in each display pixel further improve the display effect.

[0041] [Third Embodiment]

[0042] like Figure 3 As shown, the reflective display screen provided in the third embodiment of the present invention includes a first substrate 31, a second substrate 32 disposed opposite to the first substrate 31, and a cholesteric liquid crystal layer 33 disposed between the first substrate 31 and the second substrate 32. The cholesteric liquid crystal layer 33 includes cholesteric liquid crystal 331 that reflects blue light.

[0043] The reflective display screen has multiple pixel regions, including multiple first pixel regions 1a that emit red light, multiple second pixel regions 1b that emit green light, and multiple third pixel regions 1c that emit blue light. The second substrate 32 has a photoluminescent layer 34 on the side near the cholesteric liquid crystal layer 33. The photoluminescent layer 34 includes a first quantum dot layer 341, a second quantum dot layer 342, and a first transparent layer 343. The first quantum dot layer 341 is located in each of the first pixel regions 1a, the second quantum dot layer 342 is located in each of the second pixel regions 1b, and the first transparent layer 343 is located in each of the third pixel regions 1c.

[0044] Specifically, quantum dots (QDs) are nanoscale semiconductor particles that are re-excited to produce a different spectral color when blue light shines on them. The size of the QD particles determines the spectral color produced when blue light shines on them; for example, QD particles with a size of about 3 nanometers produce green light, while QD particles with a size of about 7 nanometers emit red light.

[0045] The first quantum dot layer 341 contains quantum dots that generate red light, and the second quantum dot layer 342 contains quantum dots that generate green light. When the blue light reflected by the cholesteric liquid crystal layer 33 irradiates the first quantum dot layer 341 and the second quantum dot layer 342, the first quantum dot layer 341 emits red light and the second quantum dot layer 342 emits green light.

[0046] Furthermore, the first substrate 31 is provided with multiple scan lines and multiple data lines, which intersect to define the multiple pixel regions arranged in a matrix. The first substrate 31 is also provided with multiple pixel electrodes 35, each pixel electrode 35 being spaced apart from each other, each pixel electrode 35 corresponding to a single pixel region, and each pixel electrode 35 being connected to the corresponding scan line and data line via a thin-film transistor. A common electrode 36 is provided on either the first substrate 31 or the second substrate 32 (shown on one side of the second substrate 32 in the figure). By applying a control voltage to the pixel electrodes 35 and the common electrode 36, the cholesteric liquid crystal 331 corresponding to the pixel region can be controlled to switch between a planar texture and a focal conical texture, thereby causing the cholesteric liquid crystal 331 to reflect blue light or transmit light through it.

[0047] In this embodiment, the pitch of the cholesteric liquid crystal 331 is defined by the protrusion structure disposed on the first substrate 31 or the second substrate 32.

[0048] Specifically, the pixel electrode 35 is provided with a first protrusion structure 351, the common electrode 36 is disposed on the second substrate 32, and the common electrode 36 is provided with a plurality of second protrusion structures 361, each second protrusion structure 361 corresponding to each first protrusion structure 351.

[0049] Furthermore, a reflective layer 352 is provided on the surface of the first protrusion structure 351. The reflective layer 352 can increase the reflection efficiency of the reflected light.

[0050] Furthermore, a polarizer 37 is provided on the side of the second substrate 32 away from the cholesteric liquid crystal layer 33, and the polarizer 37 is a quarter-wave plate.

[0051] Furthermore, a light-absorbing layer 38 is provided on the side of the first substrate 31 near the cholesteric liquid crystal layer 33.

[0052] Furthermore, each of the first substrate 31 and the second substrate 32 has an alignment film 41 on the side near the cholesteric liquid crystal layer 33.

[0053] The reflective display screen of this embodiment uses ambient light to display images. Therefore, the reflective display screen does not require a backlight and only needs a single-layer liquid crystal cell, further reducing the overall thickness of the display screen and simplifying its structure. In addition, the cholesteric liquid crystal layer 33 of this embodiment does not require chiral agents to adjust the pitch, and the cholesteric liquid crystal layer 33 does not require the addition of chiral agents, further simplifying the manufacturing process and reducing production costs.

[0054] [Fourth Embodiment]

[0055] The difference between the reflective display screen in this embodiment and the third embodiment is that a black matrix 39 and a color film layer 40 are provided between the second substrate 32 and the photoluminescent layer 34. The color film layer 40 is separated by the black matrix 39 and includes a red color resist layer 41, a green color resist layer 42, and a second transparent layer 43. The red color resist layer 41 is located in each first pixel region 1a, the green color resist layer 42 is located in each second pixel region 1b, and the second transparent layer 43 is located in each third pixel region 1c. The second transparent layer 43 can be a hollow structure or formed of a transparent material.

[0056] In this embodiment, the reflective display screen, by providing a color film layer 40, allows the cholesteric liquid crystal layer 33 to excite QD particles in the first quantum dot layer 341 and the second quantum dot layer 342 by reflecting only a small amount of blue light. Other structures of the reflective display screen in this embodiment can be found in the third embodiment described above, and will not be repeated here.

[0057] [Fifth Embodiment]

[0058] The difference between the reflective display screen in this embodiment and the third embodiment is that the light absorption layer 38 is not provided, and the reflective layer 352 is disposed entirely on the pixel electrode 35. Other structures of the reflective display screen in this embodiment are the same as those in the third embodiment described above, and will not be repeated here.

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A reflective display screen, characterized by The reflective display screen comprises a first substrate (31), a second substrate (32) arranged opposite to the first substrate (31), and a cholesteric liquid crystal layer (33) arranged between the first substrate (31) and the second substrate (32), and the cholesteric liquid crystal layer (33) is used for reflecting blue light; the reflective display screen is provided with a plurality of pixel regions, the plurality of pixel regions comprise a plurality of first pixel regions (1a) for emitting red light, a plurality of second pixel regions (1b) for emitting green light, and a plurality of third pixel regions (1c) for emitting blue light, the second substrate (32) is provided with a photoluminescence layer (34) on the side close to the cholesteric liquid crystal layer (33), the photoluminescence layer (34) comprises a first quantum dot layer (341), a second quantum dot layer (342), and a first transparent layer (343), the first quantum dot layer (341) is arranged in each first pixel region (1a) correspondingly, the second quantum dot layer (342) is arranged in each second pixel region (1b) correspondingly, and the first transparent layer (343) is arranged in each third pixel region (1c) correspondingly; the first quantum dot layer (341) is provided with quantum dots for exciting and generating red light by irradiating blue light, and the second quantum dot layer (342) is provided with quantum dots for exciting and generating green light by irradiating blue light; a black matrix (39) and a color film layer (40) are arranged between the second substrate (32) and the photoluminescence layer (34), the color film layer (40) is spaced apart by the black matrix (39), the color film layer (40) comprises a red color resistance layer (41), a green color resistance layer (42), and a second transparent layer (43), the red color resistance layer (41) is arranged in each first pixel region (1a) correspondingly, the green color resistance layer (42) is arranged in each second pixel region (1b) correspondingly, and the second transparent layer (43) is arranged in each third pixel region (1c) correspondingly. A plurality of pixel electrodes (35) are arranged on the first substrate (31), each of the pixel electrodes (35) is arranged spaced apart from each other, and each of the pixel electrodes (35) corresponds to each of the pixel regions one by one; a first protruding structure (351) is arranged on the pixel electrode (35), a reflective layer (352) is arranged on the surface of the first protruding structure (351), a common electrode (36) is arranged on the second substrate (32), a plurality of second protruding structures (361) are arranged on the common electrode (36), and each of the second protruding structures (361) corresponds to each of the first protruding structures (351) one by one.

2. The reflective display screen of claim 1, wherein, A polaroid (37) is arranged on the side of the second substrate (32) away from the cholesteric liquid crystal layer (33), and the polaroid (37) is a quarter-wave plate.

3. The reflective display screen of claim 1, wherein, A light-absorbing layer (38) is arranged on the side of the first substrate (31) close to the cholesteric liquid crystal layer (33).

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