Dual-light video, dual-light static, and dual-light dual-state cholesteric displays

Abstract

The present invention relates to a cholesteric liquid crystal display, and more particularly, to a dual-light dual-state cholesteric liquid crystal display employing a front light system and a backlight system wherein the front light region corresponds to a reflective pixel region of a TFT storage capacitor and the backlight region corresponds to a conventional transparent pixel region. The mirror surface effect of the storage capacitor in the active matrix and the polarization-depolarization effect of the cholesteric liquid crystal are utilized, the storage capacitor area is changed into an effective display area, and the total display area of the liquid crystal display is effectively enlarged. Therefore, the liquid crystal display can be used not only under indoor ambient light conditions with excellent color gamut, but also in outdoor daylight readable applications.

Description

Technical Field

[0001] The present invention relates to a high aperture ratio thin film transistor (TFT) liquid crystal display, and more particularly, to a cholesteric liquid crystal display employing a front light system and a backlight system, wherein the front light region corresponds to the reflective pixel region of the TFT storage capacitor, and the backlight region corresponds to the conventional transparent pixel region. The front light can be a natural ambient light beam or an artificial front light surface. Therefore, the display can be used not only under various indoor ambient light conditions with excellent color gamut, but also in outdoor sunlight-readable applications. Background Art

[0002] Cholesteric liquid crystal displays are characterized in that the image remains on the display even when the driving voltage is turned off. Bistability and multistability ensure a completely flicker-free static display and offer the possibility of infinite multiplexing to produce giant displays and / or ultra-high resolution displays. In a cholesteric liquid crystal, the molecules are helically oriented with a periodic characteristic of the material. In the planar state, the axis of the helix is perpendicular to the plane of the display. Light with a wavelength matching the pitch of the helix is reflected, and the display appears bright. If an alternating current (AC) voltage is applied, the structure of the liquid crystal changes from a planar texture to a focal conic texture. The main feature of the focal conic state is its high diffused light scattering appearance caused by the distribution of smaller birefringent domains, where the refractive index changes abruptly at the boundaries between these domains. This texture has no single optical axis, and the focal conic texture is typically milky white (i.e., white light scattering). The planar texture and the focal conic texture can coexist in the same panel or entity, which is a very important property for display applications and enables gray levels to be achieved.

[0003] Current cholesteric displays utilize "Bragg reflection", one of the inherent properties of the cholesteric phase. In Bragg reflection, only part of the incident light having the same handedness of circular polarization and within a specific wavelength band can be reflected to the viewer, resulting in a monochromatic display. However, the remaining spectrum of the incident light (including 50% with the opposite handedness of circular polarization and outside the Bragg reflection band) will pass through the display and be absorbed by the black coating material on the back substrate of the display to ensure contrast. The overall light utilization efficiency is quite low. Bragg-type reflection gives the impression that monochromatic display is one of the unique characteristics of cholesteric liquid crystal displays (CLCDs).

[0004] U.S. Patent No. 5,796,454 describes a black and white backlit cholesteric liquid crystal (CLC) display. The black and white backlit CLC display includes: a controllable CLC structure, a first circular polarizer laminated to a first substrate having cells with the same circular polarity as the liquid crystal, a second circular polarizer laminated to a second substrate having cells with the opposite circular polarity to the liquid crystal, and a light source. The black and white backlit display is preferably illuminated by a light source that produces natural "white" light. Thus, when the display is illuminated by incident light, the circular polarizer transmits 50% of the component of the incident light that is right-handed circularly polarized. When the CLC is in the ON state, the light reflected by the CLC is the portion of the incident light having wavelengths within the inherent spectral bandwidth and the same chirality, and the portion of the light transmitted through the CLC is the complementary color of the CLC's inherent color. The transmitted light has right-handed circular polarization; however, it is thus blocked by the left-handed circular polarizer, and thus, the viewer will perceive this area of the display to be essentially black. When the display is in the OFF state, the light transmitted through the polarizer is scattered by the CLC, and the portion of the incident light that is forward-scattered is emitted from the controllable CLC structure as depolarized light, and the left-handed circularly polarized portion of the forward-scattered light is transmitted through the left-handed circular polarizer and is thus perceived by the viewer. In U.S. Patent No. 5,796,454, the black and white display is produced by a backlight assembly, and ambient light is merely noise.

[0005] U.S. Patent No. 6,344,887 describes a method of manufacturing a full-spectrum reflective cholesteric display, which is incorporated herein by reference. This patent discloses a cholesteric display that employs a polarizer having the same polarity as the liquid crystal. The display utilizes two types of reflection: Bragg reflection (first reflection) and metal reflection (second reflection). The display utilizes a circular polarizer and a metal reflective film located on the back of the display to direct a second component of the incident light back to the viewer.

[0006] U.S. Patent No. 6,873,393 describes a method of manufacturing a black and white or color cholesteric display without using Bragg reflection, which is incorporated herein by reference. This patent discloses a cholesteric display that employs a front polarizer having the opposite polarity to the liquid crystal. The function of the display cell structure is merely to act as a light shutter for turning ON and OFF the incident light. In the black and white display mode, the white state is achieved by the metal reflection in the cholesteric planar texture region, and the black state is obtained by the cholesteric depolarization effect in the cholesteric focal conic texture region and the filtering effect of the polarizer. In the full-color mode, the full-color state is produced by the metal reflector and microfilters in the cholesteric planar texture region, and the black state is achieved by the cholesteric focal conic texture region.

[0007] U.S. Patent No. 7,564,518 describes a reflective cholesteric display using two circular polarizers. The front circular polarizer has a predetermined polarity opposite to both the Bragg reflection of the display and the back-reflective circular polarizer. The display system uses an absorptive weak polarizer with high transmittance. In the black-and-white display mode, the white state is achieved by the cholesteric focal conic texture region, and the black state is obtained by the cholesteric planar texture region. In the full-color mode, the full-color state is generated by the microfilters in the cholesteric focal conic texture region, and the black state is achieved by the cholesteric planar texture region.

[0008] Patent US20200233254A1 describes a cholesteric display using a substrate with a mirror, where the monochromatic liquid crystal structure includes a field-induced nematic vertical alignment texture and a cholesteric focal conic texture, which are incorporated herein by reference. The front circular polarizer is attached to the front substrate. The mirror covers all ITO common areas and the drain regions of the TFTs to make the display a pure reflective cholesteric display device, which is an ideal solution for black-and-white displays. However, when it is used in full-color display applications (where the color filter (CF) is set in front of the substrate and the front light passes through the CF film twice via the reflective metal layer), the color quality (e.g., color saturation and color brightness) is not as good as that of a single-pass backlight display. Summary of the Invention

[0009] The main object of the present invention is to achieve a dual-light TFT cholesteric liquid crystal display with front light and backlight.

[0010] Another object of the present invention is to create a color filter pattern that covers the storage capacitor regions of the TFT array or active matrix as the reflective display area.

[0011] Another object of the present invention is to create a color filter pattern to cover most of the pixel regions as the transmissive display area.

[0012] Another object of the present invention is to increase the total aperture ratio of the TFT display.

[0013] Another object of the present invention is to create a red, green, blue, and white color filter patterned pixel structure.

[0014] Another object of the present invention is to create a display structure where the reflective display and the transmissive display share the same optical on state and optical off state.

[0015] Another object of the present invention is to create a field-induced nematic vertical alignment texture as the reflective video optical off state.

[0016] Another object of the present invention is to create a field-induced nematic eddy alignment texture as a reflective video optical on state.

[0017] Another object of the present invention is to create a reflective static off state in a cholesteric planar texture.

[0018] Another object of the present invention is to obtain a reflective static on state in a cholesteric focal conic texture.

[0019] Another object of the present invention is to implement a sunlight-readable full-color display.

[0020] An embodiment of the first aspect of the present invention provides a dual-mode video cholesteric display, including a transparent conductive front substrate with a color filter layer, a first circular polarizer layer, a cholesteric liquid crystal layer, an active matrix back substrate, a second circular polarizer layer, a backlight surface, and a frontlight surface. The cholesteric liquid crystal layer has at least one field-induced vertical alignment region and at least one field-induced eddy alignment region. The active matrix back substrate has a first displayable window region and a second displayable window region. Wherein, the transparent conductive front substrate together with the first circular polarizer layer, the cholesteric liquid crystal layer, and the active matrix back substrate together with the second circular polarizer layer are juxtaposed to form a display structure. Wherein, the backlight beam from the backlight surface passing through the first displayable window region and the field-induced eddy alignment region is modulated into depolarized light to form an optical on state with at least one gray level; the backlight passing through the first displayable window region and the field-induced vertical alignment region is absorbed by the first circular polarizer layer and the second circular polarizer layer to form an optical off state. Wherein, the frontlight beam from the frontlight surface reflected from the second displayable window region of the active matrix substrate through the field-induced eddy alignment region is modulated into depolarized light to form an optical on state with at least one gray level; the frontlight reflected from the second displayable window region through the field-induced vertical alignment region is absorbed by the first circular polarizer layer to form an optical off state. Wherein, the field-induced vertical alignment region and the field-induced eddy alignment region can be instantaneously interchanged at video frequencies, whereby a viewer will observe a high-brightness video-rate full-color moving picture under indoor and outdoor environmental conditions.

[0021] In some embodiments, the first circular polarizer layer and the second circular polarizer layer have opposite polarities.

[0022] In some embodiments, the first displayable window region is a conventional transmission region of the active matrix.

[0023] In some embodiments, the second displayable window region is a reflective metal electrode region of the storage capacitor of the active matrix.

[0024] In some embodiments, high-brightness display under indoor and outdoor environmental conditions means that in a dark environment, the backlight is the main light source, while in outdoor conditions, the front light is the main light source.

[0025] In some embodiments, the display is a transmissive display in a dark environment.

[0026] In some embodiments, the display is a transflective display in an outdoor environment.

[0027] In some embodiments, the display is a reflective display under sunlight conditions.

[0028] In some embodiments, the video speed of the display is in the range of 30 FPS to 140 FPS.

[0029] Embodiments of the second aspect of the present invention provide a dual-light static cholesteric display, including a transparent conductive front substrate having a color filter layer, a first circular polarizer layer, a cholesteric liquid crystal layer, an active matrix back substrate, a second circular polarizer layer, a backlight surface, and a front light surface. The cholesteric liquid crystal layer has at least one cholesteric planar texture region and at least one cholesteric focal conic texture region, and the active matrix back substrate has a first displayable window region and a second displayable window region. Wherein, the transparent conductive front substrate together with the first circular polarizer layer, the cholesteric liquid crystal layer, and the active matrix back substrate together with the second circular polarizer layer are juxtaposed to form a display structure. Wherein, the backlight beam from the backlight surface passing through the first displayable window region and the cholesteric focal conic texture region is modulated into depolarized light to form an optically on state with at least one gray level; the backlight passing through the first displayable window region and the cholesteric planar texture region is absorbed by the first circular polarizer layer and the second circular polarizer layer to form an optically off state. Wherein, the front light beam from the front light surface reflected by the second displayable window region of the active matrix substrate through the cholesteric focal conic texture region is modulated into depolarized light to form an optically on state with at least one gray level; the front light reflected by the second displayable window region through the cholesteric planar texture region is absorbed by the first circular polarizer layer to form an optically off state, whereby the viewer will observe a high-brightness, power-free, and flicker-free picture under indoor and outdoor environmental conditions.

[0030] In some embodiments, the optically off state in the second displayable window region is caused by a 180° phase shift of the reflective metal electrode region of the storage capacitor of the active matrix.

[0031] In some embodiments, the optically off state in the first displayable window region is caused by the circular polarization guiding effect of the cholesteric planar texture region.

[0032] In some embodiments, the optical on-states in the first displayable window region and the second displayable window region are caused by the depolarization effect of the cholesteric focal conic texture region.

[0033] In some embodiments, the sum of the areas of the first displayable region and the second displayable region is the numerator of the modified aperture ratio of the dual-mode bistable cholesteric display.

[0034] In some embodiments, the modified aperture ratio of the dual-mode bistable cholesteric display is greater than or equal to 55%. The modified aperture ratio of the dual-mode bistable cholesteric display of the present invention is at least 15% greater than the conventional aperture ratio.

[0035] Embodiments of the third aspect of the present invention provide a dual-mode bistable cholesteric display, including a transparent conductive front substrate with a color filter layer, a first circular polarizer layer, a cholesteric liquid crystal layer, an active matrix back substrate, a second circular polarizer layer, a backlight surface, and a front light surface. The cholesteric liquid crystal layer has at least one field-induced vertical alignment region in a non-steady state and at least one field-induced vortex alignment region in a non-steady state, as well as at least one cholesteric planar texture region in a bistable state and at least one cholesteric focal conic texture region in a bistable state. Wherein, the conductive front color filter substrate together with the first circular polarizer layer, the cholesteric liquid crystal layer, and the active matrix back substrate together with the second circular polarizer layer are juxtaposed to form a display structure. Wherein, the light beam from the backlight surface passing through the field-induced vortex alignment region and / or through the cholesteric focal conic texture region is modulated into depolarized light to form an optical on-state; the light passing through the field-induced vertical alignment region and / or the cholesteric planar texture region is absorbed by the first circular polarizer layer and the second circular polarizer layer to form an optical off-state. Wherein, the light beam reflected from the metal electrode through the field-induced vortex alignment region and / or through the cholesteric focal conic texture region from the front light surface is modulated into polarized light to form an optical on-state; the light reflected from the metal electrode through the field-induced vertical alignment region and / or the cholesteric planar texture region is absorbed by the first circular polarizer layer to form an optical off-state, whereby a viewer will observe a video display and a static display in indoor and outdoor environments respectively.

[0036] In some embodiments, the video display state and the static display state are controllable cholesteric display states.

[0037] In some embodiments, the video display is a dynamic browsing mode display.

[0038] In some embodiments, the static display is a static power-free and flicker-free reading and learning mode display.

[0039] In some embodiments, the optical switching effect is caused by the polarization and depolarization effects of cholesteric molecules.

[0040] The present invention utilizes the mirror effect of the storage capacitor in the active matrix and the polarization-depolarization effect of the cholesteric liquid crystal to turn the storage capacitor area into an effectively displayable area, effectively expanding the total display area of the liquid crystal display. Therefore, the high aperture ratio TFT liquid crystal display of the present invention can be used not only under indoor ambient light conditions with excellent color gamut, but also in outdoor sunlight-readable applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1a Shows a schematic structure of a prior art TFT cholesteric display.

[0042] Figure 1b Shows a schematic aperture structure of a prior art TFT cholesteric display.

[0043] Figure 2a and Figure 2b Shows a schematic aperture structure of a reflective and transmissive full-color TFT cholesteric display.

[0044] Figure 3 Shows the optical behavior of frontlight and backlight displays in a bistable cholesteric display mode.

[0045] Figure 4 Shows the optical behavior of frontlight and backlight displays in a non-steady-state field-induced nematic display mode.

[0046] Figure 5 Shows the optical behavior of a dual-light dual-state display.

[0047] Figure 6 Shows a sub-pixel picture of a dual-light TFT design.

[0048] Figure 7 Shows the switching between a video non-steady-state display mode and a power-free bistable display mode.

[0049] Figure 8 Shows a first static color picture of a moving video stream.

[0050] Figure 9 Shows a second static color picture of the same moving video stream. DETAILED DESCRIPTION

[0051] First, refer to Figure 1a, which shows a schematic structure of a prior art TFT pattern of a cholesteric display. The metal gate 101 is one of the horizontal scan lines of the TFT array structure directly deposited on the TFT substrate through a first lithographic patterning process. The metal source 102 is one of the vertical data lines of the TFT array structure. The transparent conductive ITO electrode 103 occupies most of the area of the pixel. The thin film transistor island 104 including the gate, source, and drain triodes is located at the corner of the TFT pixel region, where the gate contacts the scan line 101, the source contacts the data line 102, and the drain contacts the transparent conductive electrode 103. The metal electrode is isolated from the overlapping part of the transparent electrode 103 by a thin silicon nitride layer to form the storage capacitor region 105. Whether it is the gate (capacitor on gate, COG) or the common electrode (common capacitor, COC), the storage capacitor is essential for working with the cholesteric liquid crystal to sufficiently hold the charge during the frame addressing process. However, the presence of the storage capacitor has a negative impact on the aperture ratio of the backlight display.

[0052] Now turn to Figure 1b , which shows Figure 1a the aperture area of the TFT pixel shown in. The dashed area 108 represents the pixel area (PA) of the TFT. For a black and white display, the dashed area 108 can be square, and for a full-color display, the dashed area 108 can be rectangular. The area 106 is the aperture of the TFT pixel, that is, the CF window structure that allows the backlight to pass through. The remaining area 107 covered by the black matrix (BM1) on the common substrate is opaque to both the artificial backlight and the natural ambient light. The ratio of the area of the area 106 to the area of the area 108 is generally called the aperture ratio (AR) of the display, which can be defined by Equation 1:

[0053]

[0054] The AR is in the range of 0.3 to 0.6, depending on the resolution of the display. In the Figure 1a and Figure 1b example shown, the AR is 0.45, which is a common value for high-resolution TFT displays.

[0055] Now turn to Figure 2a and Figure 2b, which shows a schematic structure of a reflective and transmissive full-color TFT cholesteric display. The dashed region 208 represents the black matrix region BM2 of the newly designed TFT pixel, which fully covers the TFT thin film transistor island, gate, and source to prevent light leakage from the TFT pixel. Obviously, the BM2 region 208 is a non-display region. The first displayable area (FDA) 206 is a window structure covered by a part of a predetermined color filter, which allows the backlight 220 to pass through to form a light beam 221. The second displayable area (SDA) 207 is a window structure covered by another part of the predetermined color filter on the opaque storage capacitor 215 region, which allows the front light 230 to be reflected as a light beam 231 to the viewer. Therefore, the FDA 206 is the backlight area, and the SDA 207 is the front light area. Obviously, the FDA 206 corresponds to Figure 1b the CF region 106 shown. The relationship between BM1 and BM2 can be defined by Equation 2:

[0056] BM2 = BM1 - SDA(2)

[0057] The working principle of the dual-light display will be described later.

[0058] Compared with Figure 1b the AR of the existing cholesteric TFT display introduced in

[0059] PA = FDA + SDA + BM2(3)

[0060] The relationship between MAR and AR can be described by Equation 4:

[0061]

[0062] It is fully understandable in the art that AR is restricted by the TFT design, especially limited by the resolution of the display. The higher the resolution of the display, the lower the AR. The opaque storage capacitor region is one of the main factors affecting the aperture ratio of the display. However, the latest technology in the present invention turns the storage capacitor region into the second displayable area SDA that can be effectively displayed by utilizing the mirror effect of the aluminum electrode of the storage capacitor and the polarization-depolarization effect of the cholesteric liquid crystal, thereby expanding the total display area by 15 - 20%.

[0063] Different from the conventional transflective display (which sacrifices the aperture ratio by using a specific internal structure or sacrifices the brightness of the display by some transflective coatings outside the TFT panel), the applicant prefers to name this new type of display the front light and backlight dual-light dual-state cholesteric display (DBCD).

[0064] As an embodiment of the present invention, Figure 3 Figure 3 is a cross-sectional structure of a dual-mode static cholesteric display, i.e., a front-light and backlight display in a static display mode. The dual-mode static cholesteric display 301 includes a transparent conductive front substrate 310, a cholesteric liquid crystal layer 340, an active matrix 322, and a back substrate 320. One side of the transparent conductive front substrate 310 has a color filter layer 311, and the other side has a first circular polarizer layer 330. A common electrode layer 312 is sputtered on the top of the color filter layer 311. The active matrix 322 is fabricated on the inner side of the back substrate 320 to form an active matrix back substrate 302. A second circular polarizer layer 331 is attached to the outer side of the back substrate 320. A storage capacitor 321 is also provided on the active matrix 322. It should be noted that the transparent conductive front substrate 310 having a color filter layer may be that the transparent conductive front substrate 310 itself has a color filter layer, i.e., the transparent conductive front substrate 310 and the color filter layer are an integral body, or the transparent conductive front substrate 310 and the color filter layer are two relatively independent layers, and the combination of the two is included within the protection scope of the present invention.

[0065] The cholesteric liquid crystal layer 340 includes at least one cholesteric planar texture region 341 and at least one cholesteric focal conic texture region 342. The active matrix back substrate 302 includes a first displayable window region 303 and a second displayable window region 304. The reflective metal electrode region of the storage capacitor 321 forms the second displayable window region 304.

[0066] When the cholesteric liquid crystal layer 340 is applied with a cholesteric-nematic phase transition voltage and then rapidly returns to zero voltage, the liquid crystal molecules will gradually form a stable cholesteric planar texture 341, and thus the display remains in an optically off state. The backlight beam 350 from the backlight panel passes through the backlight surface and reaches the right-handed (RH) second circular polarizer layer 331, and is converted into RH circularly polarized light, which will continue to pass through the cholesteric planar texture 341 of the liquid crystal layer without attenuation and phase change. Finally, the light component will be substantially absorbed by the front left-handed (LH) first circular polarizer layer 330. Therefore, the viewer will not see light. At the same time, the front light beam 360 (whether it is artificial front light or ambient light) reaches the LH first circular polarizer layer 330 and is converted into LH circularly polarized light, which will pass through the cholesteric planar texture 341 without attenuation and phase change until it is reflected by the aluminum reflective layer of the storage capacitor 321. Through this reflection, the light beam undergoes a 180° phase shift and becomes RH circularly polarized light. This light component will be substantially absorbed by the front LH first circular polarizer layer 330.

[0067] Similarly, when the liquid crystal molecules of the liquid crystal layer 340 are driven by appropriate voltage pulses to a stable cholesteric focal conic texture 342 or to a multi-stable state (cholesteric planar and focal conic coexisting texture), the display operates in an optically-on state with different gray levels. Light scattering and depolarization are typical phenomena of the cholesteric focal conic texture. As mentioned above, the planar texture and the focal conic texture can coexist in the same panel or entity, which is a very important characteristic for display applications, and thus gray levels can be achieved.

[0068] The light beam 350 from the backlight panel passes through the backlight surface and reaches the RH second circular polarizer layer 331, and more than 40% of the light beam 350 will be converted into RH circularly polarized light 351, and the light component 352 formed with a certain degree of diffusion and depolarization passes through the cholesteric focal conic texture region 342 of the liquid crystal layer. Finally, this light component will substantially pass through the front LH circular polarizer 330 to form a light component 353 with controllable intensity and color. At the same time, the front light beam 360 (whether it is artificial front light or ambient light) passes through the front light surface and reaches the LH first circular polarizer layer 330 and is converted into LH circularly polarized light 361, which will be depolarized by the focal conic texture and further reflected by the reflective metal electrode region of the storage capacitor 321, i.e., the aluminum electrode, to form RH circularly polarized light 362 through this reflection and finally appear as a light component 363. As a result, the viewer will see a color image.

[0069] As another embodiment of the present invention, Figure 4 is a cross-sectional structure of a dual-light video cholesteric display, i.e., a front light and a backlight display in a dynamic video display mode. Figure 4 The composition of the cholesteric liquid crystal layer 440 of the shown dual-light video cholesteric display is different from that of Figure 3 the cholesteric liquid crystal layer 340 of the shown dual-light static cholesteric display, but Figure 4 is Figure 3 substantially the same in the layout configuration of structures such as a transparent conductive front substrate, a color filter layer, a first circular polarizer layer, a second circular polarizer layer, and an active matrix back substrate.

[0070] Figure 4In this case, the cholesteric liquid crystal layer 440 has at least one field-induced vertical alignment region 441 and at least one field-induced vortex alignment region 442. An absorption color filter layer 311 including red, green, blue, and black light-shielding layer (BM) patterns, or in other cases including red, green, blue, white, and BM patterns, is deposited on the transparent conductive front substrate 310, and a common ITO (Indium Tin Oxides) electrode 312 is sputtered on top of the color filter layer 311 as a common electrode layer. The thickness of the color filter layer 311 is generally in the range of 0.4 - 1.2 microns, preferably 0.8 - 1.0 microns. A polyimide alignment layer is deposited on top of the common electrode layer. In addition, a first circular polarizer layer 330 is located outside the transparent conductive front substrate 310; the TFT active matrix 322 is fabricated on the inner side of the back substrate 320 to form an active matrix back substrate 302, and a storage capacitor 321 is arranged on the TFT active matrix 322, where the storage capacitor 321 occupies approximately 20% of the pixel area of the TFT active matrix back substrate 302. A second circular polarizer layer 331 is attached to the outside of the back substrate 320. The optical helices of the first circular polarizer layer 330 and the second circular polarizer layer 331 are designed to be opposite to each other.

[0071] Inside the TFT active matrix back substrate 302, a gate line for transmitting a scan signal from the outside, a gate electrode as a branch of the gate line, and a storage capacitor electrode parallel to the gate line are formed on a transparent insulating substrate such as glass of the back substrate 320, and a gate insulating layer is formed on the transparent insulating substrate. A data line perpendicular to the gate line and transmitting a display signal from the outside is formed on a part of the gate insulating layer. A semiconductor and an N+ layer are formed on the gate insulating layer and the gate electrode. A source electrode and a drain electrode are formed on the layer with ohmic contact, and the source electrode is connected to the data line. In this embodiment, the gate electrode, the source electrode, the drain electrode, the gate insulating layer, and the semiconductor and N+ layer form the TFT active matrix 322, and a channel of the TFT is generated in a part of the amorphous silicon layer (a-Si) layer between the source electrode and the drain electrode. When a scan signal is applied to the gate electrode through the gate line, the TFT is turned on; and the driving voltage of the display is applied to the source electrode through the data line, and then applied to the drain electrode through the channel in the a-Si layer. Charge is effectively stored in the storage capacitor 321 inside the cell with a retention rate of 99%. The voltage drops from the transparent insulating substrate (i.e., the back substrate 320) of the TFT active matrix back substrate 302 to the transparent conductive front substrate 310 to address the cholesteric liquid crystal layer 440 to different controllable optical states, and the transparent conductive front substrate 310 is a common substrate.

[0072] The cholesteric liquid crystal layer 440 has at least one field-induced vertical alignment region and at least one field-induced eddy alignment region. When the cholesteric liquid crystal layer 440 is addressed in a field-induced vertical alignment (FVA) texture 441 by a driving voltage level, the display operates in an optically off state. The backlight beam 450 from the backlight panel passes through the backlight surface to the right-handed (RH) second circular polarizer layer 331 and is converted into RH circularly polarized light, which will continue to pass through the liquid crystal FVA texture 441, i.e., the field-induced vertical alignment region, without attenuation and phase change. Finally, the light component will be substantially absorbed by the front left-handed (LH) first circular polarizer layer 330. Therefore, the viewer will not see light. At the same time, the front light beam 460 (whether artificial front light or ambient light) reaches the LH first circular polarizer layer 330 and is converted into LH circularly polarized light, which will pass through the liquid crystal FVA texture without attenuation and phase change until it is reflected by the aluminum reflector of the storage capacitor 321. Through this reflection, the beam is phase-shifted by 180° to become RH circularly polarized light. This light component will be substantially absorbed by the front LH first circular polarizer layer 330.

[0073] Similarly, when the cholesteric liquid crystal layer 440 is addressed in a field-induced eddy alignment (FEA) texture 442, the display operates in an optically on state with different gray levels. At the same driving voltage level, the field-induced nematic liquid crystal has the same tilt angle θ with respect to the normal direction but has different domain orientations. There are many domains in the FEA, where the tilt angle θ with respect to the normal direction of the display is the same, but the azimuth angle can vary in the range of 0° to 180°. The tilt angle θ is inversely proportional to the driving voltage and varies in the range of 0° to 90°. Liquid crystal eddies can be formed between domains, and the size and shape of the eddies depend on the driving voltage, the surface alignment material, and the elastic properties of the liquid crystal. Light scattering and depolarization are typical phenomena of the eddy effect. It should be noted that both the FVA texture and the FEA texture belong to the electrically driven or field-induced nematic state, which can be simultaneously and instantaneously interchanged without any delay or relaxation process, as Figure 4 shown, which is the principle of the video speed non-steady state display of the present invention.

[0074] The light beam 450 from the backlight panel passes through the backlight surface and reaches the RH second circular polarizer layer 331, and more than 40% of the light beam 450 will be converted into RH circularly polarized light 451, and the light component 452 formed with a certain degree of diffusion and depolarization passes through the liquid crystal FEA texture, that is, the field-induced vortex alignment region 442. Finally, this component will substantially pass through the front LH circular polarizer 330 to form a light component 453 with controllable intensity and color. Generally, the larger the tilt angle and the lower the voltage applied thereto, the higher the brightness of the emitted light generated. At the same time, the front light beam 460 (whether it is artificial front light or ambient light) passes through the front light surface and reaches the LH first circular polarizer layer 330 and is converted into LH circularly polarized light 461, which will be depolarized by the liquid crystal FVA texture, that is, the field-induced vertical alignment texture 441, and is further reflected by the reflective metal electrode region of the storage capacitor 321, that is, the aluminum electrode. Through this reflection, the light beam is converted into RH circularly polarized light 462 and finally appears as a light component 463. As a result, the viewer will see a color image.

[0075] Now turning to Figure 5 , which shows four pixel images of a dual-light dual-state TFT display, where the first pixel contains a static cholesteric liquid crystal planar texture 541, the second pixel contains a static cholesteric liquid crystal focal conic texture 542, the third pixel contains a dynamic field-induced vertical alignment texture 543, and the fourth pixel contains a dynamic field-induced vortex alignment texture 544.

[0076] As Figure 5 described, the cholesteric liquid crystal planar texture 541 contained in the first pixel and the cholesteric liquid crystal focal conic texture 542 contained in the second pixel constitute the optical dark state and the optical bright state of static and steady-state displays. When a phase transition voltage of cholesteric phase - nematic phase is applied to the cholesteric liquid crystal layer 540 and then quickly passes to zero voltage, the liquid crystal molecules will gradually form a stable cholesteric planar texture 541 (cholesteric planar texture), so the display remains in the optical off state. The backlight beam 550 from the backlight panel passes through the backlight surface and reaches the right-handed (RH) second circular polarizer layer 331, and is converted into RH circularly polarized light 551, which will continue to pass through the cholesteric planar texture 541 of the liquid crystal layer without attenuation and phase change. Finally, the light component will be substantially absorbed by the front left-handed (LH) first circular polarizer layer 330. Therefore, the viewer will not see light. At the same time, the front light beam 560 (whether it is artificial front light or ambient light) reaches the LH first circular polarizer layer 330 and is converted into LH circularly polarized light 561, which will pass through the cholesteric planar texture without attenuation and phase change until it is reflected by the aluminum reflective layer of the storage capacitor 321. Through this reflection, the light beam becomes RH circularly polarized light 562 through a 180° phase shift. This light component will be substantially absorbed by the front LH first circular polarizer layer 330.

[0077] Similarly, when the liquid crystal molecules of the liquid crystal layer 540 are driven by an appropriate voltage pulse to a stable cholesteric focal conic texture 542 or to a multi-stable state (cholesteric planar and focal conic coexisting texture), the display operates in an optically-on state with different gray levels. Light scattering and depolarization are typical phenomena of the cholesteric focal conic texture. As described above, the planar texture and the focal conic texture can coexist in the same panel or entity, which is a very important characteristic for display applications, and thus gray levels can be achieved.

[0078] The light beam 550 from the backlight panel passes through the backlight surface and reaches the RH second circular polarizer layer 331, and more than 40% of the light beam 550 will be converted into RH circularly polarized light, and the light component 552 formed by depolarization with a certain degree of diffusion passes through the cholesteric focal conic texture region of the liquid crystal layer. Finally, this component will substantially pass through the front LH circular polarizer 330 to form a light component 556 with controllable intensity and color. At the same time, the front light beam 560 (whether it is artificial front light or ambient light) passes through the front light surface and reaches the LH first circular polarizer layer 330 and is converted into LH circularly polarized light, which will be depolarized by the focal conic texture and further reflected by the reflective metal electrode region, i.e., the aluminum electrode, of the storage capacitor 321, and finally appears as a light component 563. As a result, the viewer will see a color image.

[0079] As Figure 5As described above, the dynamic field-induced vertical alignment texture 543 contained in the third pixel and the dynamic field-induced eddy alignment texture 544 contained in the fourth pixel constitute the optical dark state and the optical bright state of the dynamic display. When the cholesteric liquid crystal layer 540 is addressed in the field-induced vertical alignment (FVA) texture 543 by a driving voltage level, the display operates in the optically off state. The backlight beam 550 from the backlight panel passes through the backlight surface and reaches the right-handed (RH) second circular polarizer layer 331, and is converted into RH circularly polarized light 553, which will continue to pass through the liquid crystal FVA texture, i.e., the field-induced vertical alignment region, without attenuation and phase change. Finally, the light component will be substantially absorbed by the front left-handed (LH) first circular polarizer layer 330. Therefore, the viewer will not see light. At the same time, the front light beam 560 (whether it is artificial front light or ambient light) reaches the LH first circular polarizer layer 330 and is converted into LH circularly polarized light 564, which will pass through the liquid crystal FVA texture without attenuation and phase change until it is reflected by the aluminum reflector of the storage capacitor 321. Through this emission, the light beam becomes RH circularly polarized light 565 through a 180° phase shift. This light component will be substantially absorbed by the front LH first circular polarizer layer 330.

[0080] Similarly, when the liquid crystal layer 540 is addressed in the field-induced eddy alignment (FEA) texture 544, the display operates in the optically on state with different gray levels. At the same driving voltage level, the field-induced nematic liquid crystal has the same tilt angle θ with respect to the normal direction, but has different domain orientations. There are many domains in the FEA, where the tilt angle θ with respect to the normal direction of the display is the same, but the azimuth angle can vary in the range of 0° to 180°. The tilt angle θ is inversely proportional to the driving voltage, and it varies in the range of 0° to 90°. Liquid crystal eddies can form between the domains, and the size and shape of the eddies depend on the driving voltage, the surface alignment material, and the elastic properties of the liquid crystal. Light scattering and depolarization are typical phenomena of the eddy effect. It should be noted that both the FVA texture and the FEA texture belong to the electrically driven or field-induced nematic state, which can be simultaneously and instantaneously interchanged without any delay or relaxation process.

[0081] The light beam 550 from the backlight panel passes through the backlight surface and reaches the RH second circular polarizer layer 331, and more than 40% of the light beam 550 will be converted into RH circularly polarized light, which passes through the liquid crystal FEA texture, i.e., the field-induced eddy orientation region, with a certain degree of diffusion and depolarized light 554. Finally, this component will substantially pass through the front LH first circular polarizer layer 330 to form a light component 557 with controllable intensity and color. Generally, the larger the tilt angle and the lower the voltage applied thereto, the higher the brightness of the emitted light will be. At the same time, the front light beam 560 (whether it is artificial front light or ambient light) passes through the front light surface and reaches the LH first circular polarizer layer 330 and is converted into LH circularly polarized light, which will be depolarized by the FEA texture and reflected by the metal electrode region of the storage capacitor 321 to become reflected light 566, and finally form an emitted light component 567 through the first circular polarizer layer 330. As a result, the viewer will see a color image.

[0082] As yet another important embodiment of the present invention is a dual-light dual-state cholesteric display. A combination of a bistable cholesteric display and a non-stable cholesteric display has been described in Figure 5 and can be seamlessly combined to achieve a dual-light dual-state TFT display. The term "dual-state" means that the display can operate in a power-off static mode and a video-rate dynamic mode. In U.S. Patent Application 17 / 842318, the applicant has comprehensively introduced the optoelectronic working principle, electronic driving method, or voltage waveform of the new display, which is described in detail as follows:

[0083] 1. Driving of the cholesteric planar state

[0084] When the display is just manufactured from the LCD production line, the initial state will be the cholesteric planar texture or the optically dark state. When the driving voltage level rises from zero to the level V1 (V < V1), the display remains in the steady-state planar state.

[0085] 2. Cholesteric planar to focal cone transition

[0086] In the rising part of the curve where the voltage level is between V1 and V2 (V1 < V ≤ V2), a cholesteric phase transition from the planar state to the focal cone state occurs. Within this part, the helical pitch of the cholesteric phase structure remains the same, but its helical axis becomes more random with the increase of the voltage. At this time, it is a state where the planar and focal cone coexist. The transmittance of the curve allows for arranging many gray levels for the static display, which can be called the multistability of the cholesteric display. The rising part of the curve (referred to as γ1 in this article) has a positive slope.

[0087] 3. Driving of the saturated cholesteric focal cone state

[0088] In the voltage range V2 < V < V3, the display presents a saturated cholesteric focal conic state and has the brightest luminance. The voltage V3 can also be expressed as V th , which is the threshold voltage from the cholesteric state to the field-induced nematic state.

[0089] 4. Driving of the field-induced vortex state

[0090] When the increasing voltage crosses V th , the EO curve gradually decreases from the optically-on (ON) state to the optically-off (OFF) state. This is a dynamically turbulent state excited by the voltage V, where V3 < V ≤ V4, and the luminance of the display decreases as the voltage increases. The tilt angle θ of the liquid crystal molecules varies from 0 to π as a function of the driving voltage. In the present invention, the transmission of the descending curve can be allowed to arrange many gray levels of the non-steady-state display, and this part of the descending curve can be defined as γ2 with a negative slope.

[0091] 5. Driving of the field-induced vertical alignment state

[0092] When the voltage exceeds V4 (V ≥ V4), the field-induced vertical alignment state can also be simplified to the "H" state in the field. In the "H" state, the liquid crystal molecules are vertically aligned (VA) with the substrate of the display, so that the display presents the minimum transmittance or the optically-off (OFF) state.

[0093] 6. Phase separation line

[0094] On the right side of the phase separation line is the field-induced nematic phase, in which a non-steady-state display mode with video rate and multiple gray levels can be achieved. On its left side is the cholesteric phase, in which a bistable or multistable gray level display mode can be obtained. Through the fast path across the phase separation line, the non-steady-state mode and the bistable mode can be interchanged. The fast path represents the relaxation mechanism from the vertical alignment texture to the planar texture, and the molecular relaxation of the liquid crystal is the bridge connecting these two display modes. The relaxation process can be divided into four stages: first, the delay time when the vertical alignment structure still exists in the cell; second, the fast relaxation period when the transient planar structure is formed; third, when the equilibrium pitch is reached; and finally, the slow relaxation period when the final planar structure is formed. Initially, by changing the polar angle of the director orientation (the angle between the director and the normal of the cell surface) from 0 to π / 2 (about 1.25 milliseconds), the liquid crystal changes from the vertical alignment through the intermediate conical structure to the quasi-equilibrium transient planar state. The fact that the relaxation of the equilibrium wavelength is completed within about 10 milliseconds means that the equilibrium cholesteric pitch is reached, and the next relaxation process is only a macroscopic structure change. After removing the electric field, the relaxation time interval is 0.5 milliseconds to 10 milliseconds.

[0095] Based on the above EO curve, the driving device of the non-steady-state video display can be described as follows:

[0096] 1. Startup

[0097] Whether it is a brand - new display provided by the display manufacturer or a display in a power - off static state, a voltage pulse higher than V4 with a sufficient pulse width is applied to all pixels of the display panel to set the display to the black - field vertical alignment state. The startup time does not affect the video frame rate because it is part of the pipeline waveform.

[0098] 2. Frame Addressing

[0099] All levels of the analog signal with voltage levels in the range of curve γ2 (V3 < V ≤ V4) are sorted line - by - line by the TFT gate signal and latched to each individual TFT source of the sub - pixel. The liquid crystal molecules in the TFT array will be instantaneously addressed to a predetermined optical on (ON), off (OFF), and / or gray level, where the gray level or total color is determined by a hardware ladder circuit and pulse - width modulation (PWM). For example, if a ladder circuit including a series of resistors and operational amplifier ICs generates 64 voltages: v0, v1, v2, v i …v 63 and PWM provides 4 levels of Vrms, the combined gray level of each color is 256. There are three primary colors, red, green, and blue, for color reproduction, so the total number of colors in the display will exceed 16 million. The bias voltage v i (i = 0~63) represents the gray - level voltage according to curve γ2, and the values of the resistors are determined by γ2 correction to achieve a linear gray level for the human eye.

[0100] 3. Frame Sequencing

[0101] When displaying the current image, the next - frame data is restored in the frame buffer transferred from the shift register and DA (Digital - to - Analog) converter. To cancel the DC (Direct Current) component, frame - to - frame or line - to - line inversion can be used in the driving scheme. The frame rate can be in the range of 30 to 140 frames per second (FPS), and most preferably, the frame rate is 60 to 100 FPS. It should be noted that this driving device works in the field - induced nematic state without phase changes and relaxations as in the prior - art monostable displays.

[0102] 4. Dual - Mode Conversion

[0103] When the non-steady-state video display switches to the bistable display, a control signal is sent to the frame buffer to lock a predetermined image, switch the trapezoidal circuit from curve γ2 (V3 < V ≤ V4) to curve γ1 (V1 < V ≤ V2), and simultaneously set all liquid crystal pixels from the field-induced nematic state to the cholesteric planar state via the fast path. The display will be ready to address the specified static image.

[0104] Therefore, all levels of the analog signal with voltage levels in the range of curve γ1 (V1 < V ≤ V2) are sorted in a line-by-line scan controlled by the TFT gate signal and latched to each individual TFT source of the sub-pixels. Instantaneously, the liquid crystal and / or gray level, gray level or total color are determined by the hardware trapezoidal circuit and PWM. For example, if the trapezoidal circuit including a series of resistors and operational amplifier ICs generates 64 voltages: v’0, v’1, v’2, v’ i …v’ 63 and PWM provides 4 levels of Vrms, the total number of colors will exceed 16 million. The bias voltage v’ i (i = 0~63) represents the gray level voltage according to curve γ1, and the values of the resistors are determined by γ1 correction to achieve a linear gray level for the human eye. Once the data addressing of the final row is completed, the image is fixed by suddenly and simultaneously switching all sub-pixels to zero voltage. Finally, the zero-field bistable image will be recognized by the observer.

[0105] Obviously, curves γ1 and γ2 are different (v’ i ≠v i ), the former is positive while the latter is negative. For example, given a certain display transmittance T 50 , there are two voltages respectively derived from the trapezoidal circuit V γ2 and V γ1 , the first is for video-speed non-steady-state addressing, and the second is for static bistable image addressing.

[0106] The dual-mode display allows a wide range of frame rate modulation from 0 to 140 FPS, which is better than any other currently available displays, including electronic ink (E-ink) displays, organic light-emitting diode (OLED) displays, and ordinary liquid crystal displays (LCDs). The zero-FPS full-color display is an ideal display for new e-books, where low power consumption, no flicker, and low eye fatigue are the key parameters that end-users care about. In addition, the 140-FPS display meets the standards of game displays and ultra-high-speed video displays, and will be a watershed in the development of advanced display technologies, representing a new trend in the information industry.

[0107] Now turn to Figure 6, which shows the sub-pixel picture of the dual-gate TFT design, where the yellow inverted "U" pattern is the capacitor region 601, and the region BM is the black light-shielding layer. The capacitor consists of three thin films: the aluminum electrode connected to the gate line as the bottom layer, the silicon nitride as the intermediate dielectric layer, and the transparent conductive ITO as the top conductor. In the traditional backlight TFT design, the entire capacitor region is covered by a black mask on top of the display substrate, and the central green rectangular region is the area covered by the CF that allows the backlight to pass through. It is not difficult to find that the yellow storage capacitor region accounts for more than 50% of the green CF region. In this case, the traditional aperture ratio defined by the ratio of the green region area to the pixel region area is only 37.18%.

[0108] On the other hand, the new TFT design of the present invention uses a color filter film on the top substrate of the display to basically cover the storage capacitor region 601, thereby opening a second displayable area and making the modified aperture ratio (MAR) greater than or equal to 55%, such as 55% - 75%, at least 15% larger than the traditional aperture ratio. Exemplarily, the modified aperture ratio of the present invention reaches 55.63%, so that the effective display area is expanded by 18.45%. The aperture ratio of the display is related to the resolution. The higher the resolution, the relatively lower the aperture ratio of the display. Based on the design principle of the traditional TFT, the traditional aperture ratio is generally between 40% and 60%.

[0109] Now turn to Figure 7 , which shows the switching between the video non-steady display mode and the power-off bistable display mode, where the horizontal axis represents time and the vertical axis represents the frame rate defined by frames per second (FPS). The video display is addressed at 60 FPS, while the power-off bistable display operates at 0 FPS.

[0110] As Figure 7 shown, the bistable display starts with a video motion picture at 60 FPS until it reaches the "T1" moment, at which time the drive voltage waveform switches it to the bistable picture reflecting the last frame data of the previous motion picture. The interval from T1 to T2 can be a power-off and flicker-free reading time, and the static image can be maintained for a long time. Then, from the "T2" moment to the "T3" moment, the video picture is restored again, which can be controlled by a predetermined program or by an instantaneous interruption (such as a touch panel input). The interval from T3 to T4 is the second reading cycle, and thereafter the two display modes can be alternately switched. The video stream and reading are equally important. The former is an alternative to file downloading and web browsing, which is the process for the end user to obtain the file of the content before watching or reading the content. The static picture during the above alternation can be shown as the picture immediately following it.

[0111] Now turn to Figure 8, which shows the first static color picture of the motion video named "The Life of Apricot" when the video stream is interrupted at 33 seconds. According to Figure 7 shown in the chronological order, T1 = 33s, T2 = 43s. In other words, the duration of the first motion picture is 33 seconds, and the duration of the first still picture is 10 seconds.

[0112] Now turn to Figure 9 , which shows the second static color picture of the motion video named "The Life of Apricot" when the video stream is interrupted at 1 minute and 53 seconds. Where T3 = 113s, T4 = 123 seconds, and the entire video recording lasts for 4 minutes.

[0113] Although the present invention has been described in detail with its advantages, those skilled in the art should understand that various changes, substitutions, and modifications can be made herein without departing from the spirit and scope of the broadest form of the present invention.

Claims

1. A dual - light video cholesteric display, comprising: a. A transparent conductive front substrate having a color filter layer, and b. A first circular polarizer layer, and c. A cholesteric liquid crystal layer having at least one field - induced vertical alignment region and at least one field - induced vortex alignment region, and d. An active matrix back substrate having a first display window region and a second display window region, and e. A second circular polarizer layer, and f. A backlight surface, and g. A front - light surface, wherein the transparent conductive front substrate together with the first circular polarizer layer, the cholesteric liquid crystal layer, and the active matrix back substrate together with the second circular polarizer layer are juxtaposed to form a display structure; wherein the backlight beam from the backlight surface passing through the first display window region and the field - induced vortex alignment region is modulated into depolarized light to form an optically - on state with at least one gray level; the backlight passing through the first display window region and the field - induced vertical alignment region is absorbed by the first circular polarizer layer and the second circular polarizer layer to form an optically - off state; wherein the front - light beam from the front - light surface reflected from the second display window region of the active matrix back substrate through the field - induced vortex alignment region is modulated into depolarized light to form an optically - on state with at least one gray level; the front - light reflected from the second display window region through the field - induced vertical alignment region is absorbed by the first circular polarizer layer to form an optically - off state; wherein the field - induced vertical alignment region and the field - induced vortex alignment region can be instantaneously interchanged at video frequencies, whereby a viewer will observe a high - brightness video - rate full - color moving picture under indoor and outdoor environmental conditions.

2. The dual-vision video cholesteric display according to claim 1, wherein, The first circular polarizer layer and the second circular polarizer layer have opposite polarities.

3. The dual-mode video cholesteric display according to claim 1, wherein, The first display window region is a conventional transmission region of the active matrix.

4. The dual-mode video cholesteric display according to claim 1, wherein, The second display window region is a reflective metal electrode region of the storage capacitor of the active matrix.

5. The dual-mode video cholesteric display according to claim 1, wherein, High - brightness display under indoor and outdoor environmental conditions means that in a dark environment, the backlight is the main light source, while in outdoor conditions, the front - light is the main light source.

6. The dual-mode video cholesteric display according to claim 5, wherein, The display is a transmissive display in a dark environment.

7. The dual-mode video cholesteric display according to claim 5, wherein, The display is a transflective display in an outdoor environment.

8. The dual-mode video cholesteric display according to claim 1, wherein, The display is a reflective display under daylight conditions.

9. The dual-mode video cholesteric display according to claim 1, wherein, The video speed of the display is in the range of 30 FPS to 140 FPS.

10. A dual - light static cholesteric display, comprising: a. A transparent conductive front substrate having a color filter layer, and b. A first circular polarizer layer, and c. A cholesteric liquid crystal layer having at least one cholesteric planar texture region and at least one cholesteric focal - conic texture region, and d. An active matrix back substrate having a first display window region and a second display window region, and e. A second circular polarizer layer, and f. A backlight surface, and g. A front - light surface, wherein the transparent conductive front substrate together with the first circular polarizer layer, the cholesteric liquid crystal layer, and the active matrix back substrate together with the second circular polarizer layer are juxtaposed to form a display structure; Among them, the backlight beam from the backlight surface passing through the first displayable window area and the cholesteric focal conic texture area is modulated into depolarized light to form an optically on state with at least one gray level; the backlight passing through the first displayable window area and the cholesteric planar texture area is absorbed by the first circular polarizer layer and the second circular polarizer layer to form an optically off state; Among them, the frontlight beam from the frontlight surface reflected from the second displayable window area of the active matrix back substrate through the cholesteric focal conic texture area is modulated into depolarized light to form an optically on state with at least one gray level; the frontlight reflected from the second displayable window area through the cholesteric planar texture area is absorbed by the first circular polarizer layer to form an optically off state, whereby a viewer will observe a high-brightness, power-free and flicker-free image under indoor and outdoor environmental conditions.

11. The dual-mode static cholesteric display according to claim 10, wherein, The optically off state in the second displayable window area is caused by a 180° phase shift of the reflective metal electrode area of the storage capacitor of the active matrix.

12. The dual-mode static cholesteric display according to claim 10, wherein, The optically off state in the first displayable window area is caused by the circular polarization guiding effect of the cholesteric planar texture area.

13. The dual-mode static cholesteric display according to claim 10, wherein, The optically on states in the first displayable window area and the second displayable window area are caused by the depolarization effect of the cholesteric focal conic texture area.

14. The dual-mode static cholesteric display according to claim 10, wherein, The sum of the areas of the first displayable window area and the second displayable window area is the numerator of the modified aperture ratio of the dual-light static cholesteric display.

15. The dual-mode static cholesteric display according to claim 10, wherein, The modified aperture ratio of the dual-light static cholesteric display is greater than or equal to 55%.

16. A dual-light dual-state cholesteric display, comprising: a. A transparent conductive front substrate having a color filter layer, and b. A first circular polarizer layer, and c. A cholesteric liquid crystal layer having at least one field-induced vertical alignment area in a non-steady state and at least one field-induced vortex alignment area in a non-steady state, and at least one cholesteric planar texture area in a bistable state and at least one cholesteric focal conic texture area in a bistable state, and d. An active matrix back substrate, and e. A second circular polarizer layer, and f. A backlight surface, and g. A frontlight surface, wherein the conductive front color filter substrate together with the first circular polarizer layer, the cholesteric liquid crystal layer, and the active matrix back substrate together with the second circular polarizer layer are juxtaposed to form a display structure; wherein the beam from the backlight surface passing through the field-induced vortex alignment area and / or passing through the cholesteric focal conic texture area is modulated into depolarized light to form an optically on state; wherein the light passing through the field-induced vertical alignment area and / or the cholesteric planar texture area is absorbed by the first circular polarizer layer and the second circular polarizer layer to form an optically off state; wherein the beam from the frontlight surface reflected from the metal electrode through the field-induced vortex alignment area and / or through the cholesteric focal conic texture area is modulated into polarized light to form an optically on state; Among them, the light reflected from the metal electrode through the field-induced vertically aligned region and / or the cholesteric planar texture region is absorbed by the first circular polarizer layer to form an optically off state, whereby a viewer will observe a video display and a static display in indoor and outdoor environments, respectively.

17. The dual-mode dual-wavelength cholesteric display according to claim 16, wherein, The video display state and the static display state are controllable cholesteric display states.

18. The dual-mode dual-wavelength cholesteric display according to claim 16, wherein, The video display is a dynamic browsing mode display.

19. The dual-mode dual-wavelength cholesteric display according to claim 16, wherein, The static display is a static power-free and flicker-free reading and learning mode display.

20. The dual-mode dual-wavelength cholesteric display according to claim 16, wherein The optical on and off effects are caused by the polarization and depolarization effects of cholesteric molecules.

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