Display substrate and display device

Abstract

The application provides a display substrate and a display device. The display substrate comprises a first liquid crystal layer and an optical film layer. The first liquid crystal layer comprises cholesteric liquid crystal molecules, and the spiral direction of the cholesteric liquid crystal molecules is a first rotation direction. The optical film layer is located on the side of the first liquid crystal layer away from the display surface of the display substrate. The display substrate is configured to: in the case where no electric field is applied to the first liquid crystal layer, circularly polarized light of the first rotation direction in ambient light incident to the first liquid crystal layer is reflected by the first liquid crystal layer and emitted, circularly polarized light of a second rotation direction in the ambient light is incident to the optical film layer through the first liquid crystal layer and is converted into circularly polarized light of the second rotation direction incident to the first liquid crystal layer, and circularly polarized light of the second rotation direction incident to the first liquid crystal layer is emitted through the first liquid crystal layer; in the case where an electric field is applied to the first liquid crystal layer, ambient light incident to the first liquid crystal layer is incident to the optical film layer through the first liquid crystal layer and is absorbed by the optical film layer. The first rotation direction is opposite to the second rotation direction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of display, in particular to a display substrate and a display device. BACKGROUND

[0002] With the continuous development of display technology, display devices such as mobile phones, notebooks, televisions and the like have become necessities in people's work and life. Liquid crystal display devices have become mainstream display devices due to their high brightness, vivid color, wide viewing angle and other advantages.

[0003] Cholesteric liquid crystal molecules can be used in reflective display devices, which use ambient light as a light source for display, thereby reducing the power consumption of the display device. Currently, when cholesteric liquid crystal molecules are used in reflective display devices, the utilization rate of ambient light by the display device is low, and the brightness of the display device is affected. SUMMARY

[0004] The present application provides a display substrate and a display device.

[0005] According to a first aspect of an embodiment of the present application, a display substrate is provided. The display substrate comprises:

[0006] a first liquid crystal layer comprising cholesteric liquid crystal molecules, the cholesteric liquid crystal molecules having a first helical direction;

[0007] an optical film layer located on a side of the first liquid crystal layer away from a display surface of the display substrate;

[0008] The display substrate is configured to: in a case where no electric field is applied to the first liquid crystal layer, circularly polarized light of the first handedness in ambient light incident to the first liquid crystal layer is reflected by the first liquid crystal layer and exits, circularly polarized light of a second handedness in ambient light is incident to the optical film layer through the first liquid crystal layer, the circularly polarized light of the second handedness incident to the optical film layer is converted into circularly polarized light of the second handedness incident to the first liquid crystal layer, and the circularly polarized light of the second handedness incident to the first liquid crystal layer exits through the first liquid crystal layer; in a case where an electric field is applied to the first liquid crystal layer, ambient light incident to the first liquid crystal layer is incident to the optical film layer through the first liquid crystal layer and is absorbed by the optical film layer; wherein the first handedness is opposite to the second handedness.

[0009] In one embodiment, in a direction away from the first liquid crystal layer, the optical film layer comprises a first phase deviation film, a first sub-optical film layer, a second phase deviation film, a second sub-optical film layer and a reflective layer which are sequentially stacked;

[0010] The first phase deviation film and the second phase deviation film are configured to deflect the phase of the passing light by π / 2; the optical axis of the first phase deviation film is parallel to the optical axis of the second phase deviation film; the first sub-optical film layer is configured to pass the light from the first phase deviation film when no electric field is applied to the first liquid crystal layer, and deflect the phase of the light from the first phase deviation film by π / 2 and absorb the light from the second sub-optical film layer when an electric field is applied to the first liquid crystal layer; the second sub-optical film layer is configured to deflect the phase of the passing light by π / 2 when no electric field is applied to the first liquid crystal layer, and not to change the polarization direction of the passing light when an electric field is applied to the first liquid crystal layer.

[0011] In one embodiment, the first sub-optical film layer comprises a polarizing film; the pass axis of the polarizing film is deflected by 45° relative to the optical axis of the first phase deviation film along the second handedness in the direction of the optical film layer pointed by the first liquid crystal layer.

[0012] In one embodiment, the second sub-optical film layer comprises a second liquid crystal layer, and the second liquid crystal layer comprises nematic liquid crystal molecules; the orientation of the liquid crystal molecules of the second liquid crystal layer is parallel to the optical axis of the first phase deviation film when no electric field is applied to the second liquid crystal layer.

[0013] In one embodiment, the optical film layer further comprises a first electrode on the side of the second liquid crystal layer facing the first liquid crystal layer, the material of the reflective layer is conductive material, and the reflective layer comprises a second electrode; one of the first electrode and the second electrode is a pixel electrode, and the other is a common electrode.

[0014] In one embodiment, the optical film layer further comprises a first electrode on the side of the second liquid crystal layer facing the first liquid crystal layer, and a second electrode on the side of the second liquid crystal layer away from the first liquid crystal layer, and the reflective layer is on the side of the second electrode away from the first liquid crystal layer; the material of the first electrode and the second electrode is light-transmitting material.

[0015] In one embodiment, the first handedness is clockwise, and the second handedness is counterclockwise.

[0016] In one embodiment, the first handedness is counterclockwise, and the second handedness is clockwise.

[0017] In one embodiment, the cholesteric liquid crystal molecules have a plurality of different pitches, and the pitches range from nm nm; wherein n o is the ordinary refractive index of the cholesteric liquid crystal molecules, and n eThe cholesteric phase liquid crystal molecules have a non-ordinary optical refractive index.

[0018] In one embodiment, the first liquid crystal layer includes nematic liquid crystal molecules and chiral polymerizable monomers, and a concentration of the chiral polymerizable monomers in a region with a large pitch in the first liquid crystal layer is less than a concentration of the chiral polymerizable monomers in a region with a small pitch.

[0019] In one embodiment, the display substrate further includes a color filter layer on a side of the first liquid crystal layer away from the optical film layer, and the color filter layer includes color filter portions of at least three different colors.

[0020] In one embodiment, the cholesteric phase liquid crystal molecules have a pitch, and the optical film layer includes a second liquid crystal layer, and the display substrate further includes a color filter layer on a side of the second liquid crystal layer facing the first liquid crystal layer, and the color filter layer includes color filter portions of one color.

[0021] According to a second aspect of the embodiments of the present application, a display device is provided, which includes the display substrate described above.

[0022] The display substrate and the display device provided by the embodiments of the present application can improve the utilization rate of ambient light of the display device, thereby increasing the brightness of the display device. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 FIG. 1 is a partial cross-sectional view of a display substrate provided by an example embodiment of the present application;

[0024] Figure 2 FIG. 2 is a partial cross-sectional view of a display substrate provided by another example embodiment of the present application;

[0025] Figure 3 FIG. 3 is a partial cross-sectional view of a display substrate provided by still another example embodiment of the present application;

[0026] Figure 4 FIG. 4 is a partial cross-sectional view of a display substrate provided by yet another example embodiment of the present application. DETAILED DESCRIPTION

[0027] The exemplary embodiments will be described in detail herein with reference to the attached drawings. The description of the exemplary embodiments is intended to apply to various alternative embodiments as well. The following description is not limited to the exemplary embodiments, but rather, is applicable to any apparatus and method within the scope of the present application. Various embodiments described in the following examples do not represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with some aspects of the present application as set forth in the appended claims.

[0028] The terminology used in the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used in the description of the embodiments and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It also will be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0029] It should be understood that although the terms first, second, third, etc. can be used herein to describe various information, these terms are not intended to denote a particular order or hierarchy. These terms are used only to distinguish one from another. For example, a first information can be termed a second information, and similarly, a second information can be termed a first information, without departing from the scope of the present application. As used herein, the term "if' can be interpreted to mean "when" or "upon" or "in response to determining" taking into account negation that can be associated with such term.

[0030] Embodiments of the present application provide a display substrate and a display device. The display substrate and the display device in embodiments of the present application are described in detail below with reference to the drawings. The features in the following embodiments can be complementary or combined with each other without conflict.

[0031] Embodiments of the present application provide a display substrate. As shown in Figure 1 the display substrate includes a first liquid crystal layer 10 and an optical film layer 20.

[0032] The first liquid crystal layer 10 includes cholesteric liquid crystal molecules 101, and a helical direction of the cholesteric liquid crystal molecules 101 is a first handedness. The optical film layer 20 is located on a side of the first liquid crystal layer 10 away from a display surface of the display substrate. The display substrate is configured to: in a case where no electric field is applied to the first liquid crystal layer 10, circularly polarized light of the first handedness in ambient light incident to the first liquid crystal layer 10 is reflected by the first liquid crystal layer and exits, circularly polarized light of a second handedness in ambient light is incident to the optical film layer 20 through the first liquid crystal layer 10, the circularly polarized light of the second handedness incident to the optical film layer 20 is converted by the optical film layer into circularly polarized light of the second handedness incident to the first liquid crystal layer 10, and the circularly polarized light of the second handedness incident to the first liquid crystal layer 10 exits through the first liquid crystal layer 10; in a case where an electric field is applied to the first liquid crystal layer 10, ambient light incident to the first liquid crystal layer 10 is incident to the optical film layer 20 through the first liquid crystal layer 10 and is absorbed by the optical film layer 20. The first handedness is opposite to the second handedness.

[0033] The display substrate provided by the embodiments of the present application can improve the utilization rate of ambient light by the display device, thereby increasing the brightness of the display device, by disposing the optical film layer on a side of the first liquid crystal layer away from a display surface of the display substrate, reflecting the circularly polarized light of the second handedness incident to the optical film layer to convert it into the circularly polarized light of the second handedness incident to the first liquid crystal layer, and making the circularly polarized light of the second handedness incident to the first liquid crystal layer exit through the first liquid crystal layer in a case where no electric field is applied to the first liquid crystal layer. In a case where an electric field is applied to the first liquid crystal layer, ambient light incident to the first liquid crystal layer can be incident to the optical film layer through the first liquid crystal layer and be absorbed by the optical film layer, thereby realizing the dark state display of the display substrate, that is, the non-display state.

[0034] It should be noted that the first handedness and the second handedness mentioned in the embodiments of the present application are the handedness in the direction of light propagation. For example, the first handedness in the reflection and exit of the circularly polarized light of the first handedness in the ambient light incident to the first liquid crystal layer 10 refers to the handedness in the direction of the optical film layer 20 pointing to the first liquid crystal layer 10. The handedness of the liquid crystal molecules in the first liquid crystal layer also refers to the handedness in the direction of the optical film layer 20 pointing to the first liquid crystal layer 10.

[0035] In one embodiment, as Figure 1As shown, the display substrate includes a first liquid crystal cell 30, which includes a first liquid crystal layer 10. The first liquid crystal cell 30 further includes a third electrode 11 located on a side of the first liquid crystal layer 10 facing the optical film layer 20, a first driving circuit layer 14 located on a side of the third electrode 11 facing the optical film layer 20, a first substrate 15 located on a side of the first driving circuit layer 14 facing the optical film layer 20, a fourth electrode 12 located on a side of the first liquid crystal layer 10 facing away from the optical film layer 20, and a second substrate 16 located on a side of the fourth electrode 12 facing away from the optical film layer 20. One of the third electrode 11 and the fourth electrode 12 is a pixel electrode, and the other is a common electrode. An electric field can be applied to the first liquid crystal layer by the third electrode 11 and the fourth electrode 12. In some embodiments, the third electrode 11 is the pixel electrode, and the fourth electrode 12 is the common electrode. The first driving circuit layer 14 includes a plurality of pixel circuits, which are electrically connected to the third electrode 11. The first substrate 15 and the second substrate 16 are substrates with high light transmittance, such as glass substrates. The third electrode 11 and the fourth electrode 12 are electrodes with high light transmittance, for example, the third electrode 11 and the fourth electrode 12 are made of indium zinc oxide or indium tin oxide.

[0036] In one embodiment, as shown in FIG. 1, the optical film layer 20 includes a first phase deviation film 21, a first sub-optical film layer 22, a second phase deviation film 23, a second sub-optical film layer 24, and a reflective layer 25, which are sequentially stacked in a direction away from the first liquid crystal layer 10. Figure 1 As shown, the first phase deviation film 21 and the second phase deviation film 23 are configured to deflect the phase of the passing light by π / 2, and the optical axis of the first phase deviation film 21 and the optical axis of the second phase deviation film 23 are parallel to each other. The first sub-optical film layer 22 is configured to pass the light from the first phase deviation film 21 when no electric field is applied to the first liquid crystal layer 10, and deflect the phase of the light from the first phase deviation film 21 by π / 2 and absorb the light from the second sub-optical film layer 24 when an electric field is applied to the first liquid crystal layer 10. The second sub-optical film layer 24 is configured to deflect the phase of the passing light by π / 2 when no electric field is applied to the first liquid crystal layer 10, and not to change the polarization direction of the passing light when an electric field is applied to the first liquid crystal layer 10.

[0037] With this configuration, when no electric field is applied to the first liquid crystal layer 10, after ambient light is incident on the first liquid crystal layer 10, the circularly polarized light with the first rotation direction is reflected and emitted, and the circularly polarized light with the second rotation direction is incident on the first phase deviation film 21 and converted into linearly polarized light, which then passes through the first sub-optical film layer 22 and is incident on the second phase deviation film 23. The second phase deviation film 23 converts the incident linearly polarized light into circularly polarized light with the first rotation direction and it is then incident on the second sub-optical film layer 24. The second sub-optical film layer 24 converts the circularly polarized light with the first rotation direction into... The light is linearly polarized. After being reflected by the reflective layer 25, the polarization direction of the linearly polarized light remains unchanged, and it is then incident again on the second sub-optical film layer 24. The second sub-optical film layer 24 converts the linearly polarized light into circularly polarized light with a first rotation direction and it is then incident on the second phase deviation film 23. The second phase deviation film 23 converts the circularly polarized light with the first rotation direction into linearly polarized light and it passes through the first sub-optical film layer 22 to the first phase deviation film 21. The first phase deviation film 21 converts the linearly polarized light into circularly polarized light with a second rotation direction and it exits through the first liquid crystal layer 10. In this way, a bright-state display of the display substrate can be achieved, and the utilization rate of ambient light is relatively high.

[0038] like Figure 2 As shown, when an electric field is applied to the first liquid crystal layer 10, the liquid crystal molecules of the first liquid crystal layer 10 become vertically oriented. Ambient light incident on the first liquid crystal layer 10 passes through the first liquid crystal layer 10 and is incident on the first phase deviation film 21. The phase of the light incident on the first phase deviation film 21 remains unchanged, and all of it passes through the first phase deviation film 21 and is incident on the first sub-optical film layer 22. The first sub-optical film layer 22 converts the light into linearly polarized light, which is then incident on the second phase deviation film 23. The second phase deviation film 23 converts the incident linearly polarized light into circularly polarized light with a first rotation direction, which passes through the second sub-optical film layer 24 and is incident on the reflective layer 25. The reflective layer 25 converts the circularly polarized light with the first rotation direction into circularly polarized light with a second rotation direction. The circularly polarized light with the second rotation direction passes through the second sub-optical film layer 24 without changing its polarization direction and is then incident on the second phase deviation film 23. The second phase deviation film 23 converts the circularly polarized light with the second rotation direction into linearly polarized light. The linearly polarized light is then absorbed by the first sub-optical film layer 22. This enables dark-state display of the display substrate.

[0039] In one embodiment, the first sub-optical film layer 22 comprises a polarizing film; the pass axis of the polarizing film is deflected 45° relative to the optical axis of the first phase deviation film 21 along the second handedness. In this way, when no electric field is applied to the first liquid crystal layer 10, the polarization direction of the linearly polarized light incident to the polarizing film is parallel to the pass axis of the polarizing film, and thus the linearly polarized light is all transmitted through the polarizing film; when an electric field is applied to the first liquid crystal layer 10, the polarizing film converts the ambient light incident to the polarizing film from the first phase deviation film 21 into linearly polarized light. In some embodiments, the first sub-optical film layer 22 is a polarizing film. The polarizing film can be a polarizer.

[0040] In one embodiment, as shown in Figure 1 and Figure 2 the second sub-optical film layer 24 comprises a second liquid crystal layer 240, and the second liquid crystal layer 240 comprises nematic liquid crystal molecules 241; the orientation of the liquid crystal molecules of the second liquid crystal layer 240 is parallel to the optical axis of the first phase deviation film 21 when no electric field is applied to the second liquid crystal layer. In this way, when no electric field is applied to the first liquid crystal layer 10, and no electric field is applied to the second liquid crystal layer 240, the first handedness circularly polarized light incident to the second liquid crystal layer 240 from the second phase deviation film 23 is converted into linearly polarized light, and the polarization direction of the linearly polarized light is perpendicular to the pass axis of the polarizing film; when the linearly polarized light is reflected by the reflective layer 25 and then incident to the second liquid crystal layer 240 again, the second liquid crystal layer 240 converts the linearly polarized light into first handedness circularly polarized light. As shown in Figure 2 when an electric field is applied to the first liquid crystal layer 10, an electric field is applied to the second liquid crystal layer 240, and the liquid crystal molecules of the first liquid crystal layer 10 and the liquid crystal molecules of the second liquid crystal layer 240 are both converted into vertical alignment. The first handedness circularly polarized light incident to the second liquid crystal layer 240 from the second phase deviation film 23 passes through the second liquid crystal layer 240 without change in polarization direction; the first handedness circularly polarized light is reflected by the reflective layer 25 and converted into second handedness circularly polarized light; the second handedness circularly polarized light passes through the second liquid crystal layer 240 without change in polarization direction. When an electric field is applied to the first liquid crystal layer 10 and the second liquid crystal layer 240, a vertical electric field can be applied to the first liquid crystal layer 10 and the second liquid crystal layer 240, respectively.

[0041] In one embodiment, as shown in Figure 1 and Figure 2As shown, the optical film layer 20 includes a second liquid crystal cell 40, which includes a second liquid crystal layer 240, a first alignment film 28 located on a side of the second liquid crystal layer 240 facing the first liquid crystal layer 10, a first electrode 27 located on a side of the first alignment film 28 facing the first liquid crystal layer 10, a third substrate 26 located on a side of the first electrode 27 facing the first liquid crystal layer 10, a second alignment film 291 located on a side of the second liquid crystal layer 240 facing away from the first liquid crystal layer 10, a second electrode 295 located on a side of the second alignment film 291 facing away from the first liquid crystal layer 10, a second driving circuit layer 292 located on a side of the second electrode 295 facing away from the first liquid crystal layer 10, and a fourth substrate 293 located on a side of the second driving circuit layer 292 facing away from the first liquid crystal layer 10. The alignment of the first alignment film 28 and the alignment of the second alignment film 291 are parallel to the alignment of the second liquid crystal layer 240 when no electric field is applied. One of the first electrode 27 and the second electrode 295 is a pixel electrode, and the other is a common electrode. An electric field can be applied to the second liquid crystal layer 240 by the first electrode 27 and the second electrode 295. In some embodiments, the first electrode 27 is the common electrode, and the second electrode 295 is the pixel electrode. The second driving circuit layer 292 includes a plurality of pixel driving circuits, and the pixel driving circuits are electrically connected to the second electrode 295. The third substrate 26 and the fourth substrate 293 are substrates with high light transmittance, such as glass substrates.

[0042] In one embodiment, the first phase deviation film 21 and the second phase deviation film 23 can be obtained by coating a material with a phase deviation effect. In this way, the thickness of the first phase deviation film 21 and the second phase deviation film 23 can be small, which helps to reduce the thickness of the display substrate. In other embodiments, the first phase deviation film 21 and the second phase deviation film 23 can be quarter-wave plates.

[0043] In one embodiment, as shown in FIG. 1A, the first phase deviation film 21 and the second phase deviation film 23 are located on the first substrate 11 and the second substrate 21, respectively. In other embodiments, the first phase deviation film 21 and the second phase deviation film 23 can be located on the same substrate. Figure 1 Figure 2 As shown, the reflective layer 25 includes the second electrode 295, and the material of the reflective layer 25 is a conductive material. In this way, the reflective layer 25 is multiplexed as the second electrode, which helps to simplify the film layer structure of the display substrate and reduce the thickness of the display substrate. In this embodiment, the first electrode 27 is an electrode with high light transmittance, such as an indium zinc oxide or indium tin oxide. The second electrode 295 is an electrode with high reflectivity, and the second electrode 295 includes a silver film layer, such as two light-transmitting film layers and a silver film layer located between the two light-transmitting film layers.

[0044] ​In another embodiment, the reflective layer 25 is located on the side of the second electrode 295 facing away from the first liquid crystal layer 10; the materials of the first electrode 27 and the second electrode 295 are light-transmitting materials. In this embodiment, the light passing through the second liquid crystal layer 240 is incident on the reflective layer 25 after passing through the second electrode 295. The reflective layer 25 is provided with a via, and the second electrode 295 is electrically connected to the pixel circuit of the second driving circuit layer through the via of the reflective layer 25. The materials of the first electrode 27 and the second electrode 295 are, for example, indium zinc oxide or indium tin oxide.

[0045] In one embodiment, the first rotation direction is clockwise, and the second rotation direction is counterclockwise. For convenience of description, the circularly polarized light of the first rotation direction is referred to as right-handed circularly polarized light, and the circularly polarized light of the second rotation direction is referred to as left-handed circularly polarized light.

[0046] In this embodiment, when no electric field is applied to the first liquid crystal layer 10, the propagation process of the light after the ambient light is incident on the display substrate is as follows: after the ambient light is incident on the first liquid crystal layer 10, the right-handed circularly polarized light is reflected and emitted, and the left-handed circularly polarized light is converted into linearly polarized light after being incident on the first phase deviation film 21 and then passes through the first sub-optical film layer 22 to be incident on the second phase deviation film 23; the second phase deviation film 23 converts the incident linearly polarized light into right-handed circularly polarized light and then makes it incident on the second sub-optical film layer 24; the second sub-optical film layer 24 converts the right-handed circularly polarized light into linearly polarized light, and the linearly polarized light is reflected by the reflective layer 25 without changing the polarization direction, and then is incident on the second sub-optical film layer 24 again; the second sub-optical film layer 24 converts the linearly polarized light into right-handed circularly polarized light and then makes it incident on the second phase deviation film 23; the second phase deviation film 23 converts the right-handed circularly polarized light into linearly polarized light and then makes it pass through the first sub-optical film layer 22 to be incident on the first phase deviation film 21; the first phase deviation film 21 converts the linearly polarized light into left-handed circularly polarized light, and the left-handed circularly polarized light is emitted after passing through the first liquid crystal layer 10.

[0047] In this embodiment, when an electric field is applied to the first liquid crystal layer 10, the propagation process of the light after the ambient light is incident to the display substrate is as follows: after the ambient light is incident to the first liquid crystal layer 10, all the light is incident to the first phase difference film 21 through the first liquid crystal layer 10; the phase of the light incident to the first phase difference film 21 is not deflected, and all the light is incident to the first sub-optical film layer 22 through the first phase difference film 21; the first sub-optical film layer 22 converts the light into linearly polarized light incident to the second phase difference film 23; the second phase difference film 23 converts the incident linearly polarized light into right circularly polarized light and is incident to the reflective layer 25 through the second sub-optical film layer 24; the reflective layer 25 converts the right circularly polarized light into left circularly polarized light; the left circularly polarized light is incident to the second phase difference film 23 through the second sub-optical film layer 24; the second phase difference film 23 converts the left circularly polarized light into linearly polarized light; the linearly polarized light is absorbed by the first sub-optical film layer 22 after being incident to the first sub-optical film layer 22.

[0048] In another embodiment, the first rotation direction is counterclockwise, and the second rotation direction is clockwise. For convenience of description, the circularly polarized light of the first rotation direction is referred to as left circularly polarized light, and the circularly polarized light of the second rotation direction is referred to as right circularly polarized light.

[0049] In this embodiment, when an electric field is applied to the first liquid crystal layer 10, the propagation process of the light after the ambient light is incident to the display substrate is as follows: after the ambient light is incident to the first liquid crystal layer 10, all the light is incident to the first phase difference film 21 through the first liquid crystal layer 10; the phase of the light incident to the first phase difference film 21 is not deflected, and all the light is incident to the first sub-optical film layer 22 through the first phase difference film 21; the first sub-optical film layer 22 converts the light into linearly polarized light incident to the second phase difference film 23; the second phase difference film 23 converts the incident linearly polarized light into right circularly polarized light and is incident to the reflective layer 25 through the second sub-optical film layer 24; the reflective layer 25 converts the right circularly polarized light into left circularly polarized light; the left circularly polarized light is incident to the second phase difference film 23 through the second sub-optical film layer 24; the second phase difference film 23 converts the left circularly polarized light into linearly polarized light; the linearly polarized light is absorbed by the first sub-optical film layer 22 after being incident to the first sub-optical film layer 22.

[0050] In this embodiment, when an electric field is applied to the first liquid crystal layer 10, the propagation process of the light after the ambient light is incident to the display substrate is as follows: after the ambient light is incident to the first liquid crystal layer 10, all the light is incident to the first phase deviation film 21 through the first liquid crystal layer 10; the phase of the light incident to the first phase deviation film 21 is not deviated, and all the light is incident to the first sub-optical film layer 22 through the first phase deviation film 21; the first sub-optical film layer 22 converts the light into linearly polarized light incident to the second phase deviation film 23; the second phase deviation film 23 converts the incident linearly polarized light into left circularly polarized light and the left circularly polarized light is incident to the reflective layer 25 through the second sub-optical film layer 24; the reflective layer 25 converts the left circularly polarized light into right circularly polarized light; the right circularly polarized light is incident to the second phase deviation film 23 through the second sub-optical film layer 24; the second phase deviation film 23 converts the right circularly polarized light into linearly polarized light; and the linearly polarized light is absorbed by the first sub-optical film layer 22 after being incident to the first sub-optical film layer 22.

[0051] In one embodiment, the cholesteric liquid crystal molecules have a plurality of different pitches, and the pitches range from 380 nm to 780 nm. In this way, the first liquid crystal layer 10 can reflect light with a wavelength ranging from nm nm; wherein n o is the ordinary refractive index of the cholesteric liquid crystal molecules, and n e is the extraordinary refractive index of the cholesteric liquid crystal molecules. In this way, the first liquid crystal layer can reflect all light in the visible light band, so that the emitted light is white, and the display substrate can display black and white colors. The pitch, the wavelength of the light that can be reflected by the liquid crystal molecules, and the refractive index of the liquid crystal molecules satisfy the following relationship: p = λ / n. Wherein, p is the pitch, λ is the wavelength of the light that can be reflected by the liquid crystal molecules, and n is the refractive index of the liquid crystal molecules.

[0052] In one embodiment, the first liquid crystal layer 10 includes nematic liquid crystal molecules and chiral polymerizable monomers, and the concentration of the chiral polymerizable monomers in the region with a large pitch in the first liquid crystal layer is less than the concentration of the chiral polymerizable monomers in the region with a small pitch. The greater the concentration of the chiral polymerizable monomers, the shorter the pitch of the liquid crystal molecules. By controlling the concentration of the chiral polymerizable monomers in different regions of the first liquid crystal layer, the cholesteric liquid crystal molecules can have a plurality of different pitches.

[0053] In one embodiment, a first liquid crystal layer comprising cholesteric liquid crystal molecules with various pitches can be prepared by the following method: First, a nematic liquid crystal, a chiral polymerizable monomer, a photoinitiator, and an ultraviolet light absorber are mixed. The resulting mixed solvent is then dropped onto one of a first substrate and a second substrate, and the first substrate and the second substrate are aligned. Next, the mixed solvent is irradiated with ultraviolet light. Due to the presence of the ultraviolet light absorber, an ultraviolet light intensity gradient is formed between the first and second substrates when the mixed solvent is irradiated with ultraviolet light. The chiral polymerizable monomers polymerize rapidly in regions with high ultraviolet light intensity and slowly in regions with low ultraviolet light intensity, resulting in a difference in chiral polymerizable monomer concentration. This causes the chiral polymerizable monomers to diffuse from regions with high concentration to regions with low concentration, i.e., from regions with low ultraviolet light intensity to regions with high ultraviolet light intensity. Ultimately, regions with high ultraviolet light intensity have a high concentration of chiral polymerizable monomers and a short pitch, while regions with low ultraviolet light intensity have a low concentration of chiral polymerizable monomers and a long pitch. The first liquid crystal cell can be formed through the above process. The chiral polymerizable monomer can be either a left-handed or a right-handed chiral polymerizable monomer.

[0054] In one embodiment, the thickness of the first liquid crystal cell 30 is 5μm to 30μm. For example, the thickness of the first liquid crystal cell 30 is 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, etc.

[0055] In one embodiment, the thickness of the second liquid crystal cell 40 is 1 μm to 5 μm. For example, the thickness of the second liquid crystal cell 40 is 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, etc.

[0056] In one embodiment, such as Figure 3 As shown, the display substrate further includes a color filter layer 17 located on the side of the first liquid crystal layer 10 opposite to the optical film layer 20, and the color filter layer 17 includes color filters of at least three different colors. With this configuration, the display substrate can display a color image. In some embodiments, the color filter layer 17 may include color filters of red, green, and blue.

[0057] Furthermore, such as Figure 3 As shown, the color filter layer 17 is located between the fourth electrode 12 and the second substrate 16.

[0058] In another embodiment, the cholesteric liquid crystal molecules have a specific pitch. For example... Figure 4As shown, the display substrate further comprises a color filter layer 294 located on the side of the second liquid crystal layer 240 facing the first liquid crystal layer 10, the color filter layer 294 comprises a color filter part of one color, and the color of the light reflected by the cholesteric liquid crystal molecules is the same as the color of the color filter part. Thus the display substrate can display the color of the color filter part. In some embodiments, the color of the color filter part can be red, or blue, or green.

[0059] Further, as shown in FIG. 1, the display substrate further comprises a color filter layer 294 located on the side of the second liquid crystal layer 240 facing the first liquid crystal layer 10. Figure 4

[0060] The display substrate provided by the embodiments of the present application has a switching time of only a few milliseconds between the planar orientation and the vertical orientation of the cholesteric liquid crystal molecules, and the display substrate has a very fast switching speed of pictures, which helps to improve the user experience. In the embodiments of the present application, the planar orientation of the liquid crystal molecules refers to that the long axis direction of the liquid crystal molecules is parallel to the display surface of the display substrate, and the vertical orientation of the liquid crystal molecules refers to that the long axis direction of the liquid crystal molecules is perpendicular to the display surface of the display substrate.

[0061] The embodiments of the present application further provide a preparation method of the display substrate. Hereinafter, the preparation process of the display substrate shown in FIG. 1 is taken as an example to describe the preparation process of the display substrate. Figure 1

[0062] First, the first liquid crystal box 30 is prepared.

[0063] In one embodiment, the preparation process of the first liquid crystal box is as follows: the first driving circuit layer 14 and the third electrode 11 are sequentially formed on the first substrate 15 to obtain a first sub-substrate; the fourth electrode 12 is formed on the second substrate 16 to obtain a second sub-substrate; the first liquid crystal layer 10 is arranged on one of the first sub-substrate and the second sub-substrate, and the sealant is arranged on the other one, and the first sub-substrate and the second sub-substrate are subjected to lamination.

[0064] Subsequently, the second liquid crystal box 40 is prepared.

[0065] In one embodiment, the preparation process of the first liquid crystal box is as follows: the first electrode 27 and the first alignment film 28 are sequentially formed on the third substrate 26 to obtain a third sub-substrate; the second driving circuit layer 292, the reflective layer 25 and the second alignment film 291 are sequentially formed on the fourth substrate 293 to obtain a fourth sub-substrate; the second liquid crystal layer is arranged on one of the first sub-substrate and the second sub-substrate, and the sealant is arranged on the other one, and the third sub-substrate and the fourth sub-substrate are subjected to lamination.

[0066] ​​Subsequently, the first phase difference film 21, the first sub-optical film layer 22, and the second phase difference film 23 are sequentially formed on the first substrate 15 of the first liquid crystal cell 30, and the third substrate 26 of the second liquid crystal cell 40 is attached to the second phase difference film 23. Alternatively, the second phase difference film 23, the first sub-optical film layer 22, and the first phase difference film 21 are sequentially arranged on the third substrate 26 of the second liquid crystal cell 40, and the first substrate 15 of the first liquid crystal cell 30 is attached to the first phase difference film 21.

[0067] Embodiments of the preparation method of the display substrate provided by the present application belong to the same inventive concept as the embodiments of the display substrate, and the descriptions of related details and beneficial effects can be mutually referred to, which will not be described here in detail.

[0068] The present application also provides a display device. The display device includes the display substrate of any of the above embodiments.

[0069] In some embodiments, the display device further includes a housing, and the display substrate is embedded in the housing.

[0070] The display device provided by the embodiments of the present application can be any appropriate display device, including but not limited to mobile phones, tablet computers, televisions, displays, notebook computers, digital photo frames, navigation devices, e-books, and any product or component having a display function.

[0071] It should be noted that in the drawings, the sizes of the layers and regions can be exaggerated for clarity. Also, it can be understood that when an element or layer is referred to as being "on" another element or layer, it can be directly on the other element or layer, or intervening layers can also be present. Further, it can be understood that when an element or layer is referred to as being "under" another element or layer, it can be directly under the other element or layer, or one or more intervening layers or elements can also be present. In addition, it can be understood that when a layer or element is referred to as being "between" two layers or elements, it can be the only layer or element between the two layers or elements, or one or more intervening layers or elements can also be present. Similar reference numerals can indicate similar elements throughout the specification.

[0072] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the application being indicated by the following claims.

[0073] It is to be understood that the application is not limited to the precise construction already described above and shown in the drawings, and that various modifications and changes can be made by those skilled in the art without departing from the scope of the application. The scope of the application should only be limited by the claims appended hereto.

Claims

1. A display substrate, characterized in that, The display substrate includes: The first liquid crystal layer includes cholesteric liquid crystal molecules, wherein the helical direction of the cholesteric liquid crystal molecules is a first helical direction; An optical film layer is located on the side of the first liquid crystal layer that faces away from the display surface of the display substrate; The display substrate is configured such that, when no electric field is applied to the first liquid crystal layer, circularly polarized light of the first rotation direction in ambient light incident on the first liquid crystal layer is reflected and emitted by the first liquid crystal layer, and circularly polarized light of the second rotation direction in the ambient light is incident on an optical film layer through the first liquid crystal layer; the circularly polarized light of the second rotation direction incident on the optical film layer is converted into circularly polarized light of the second rotation direction incident on the first liquid crystal layer, and the circularly polarized light of the second rotation direction incident on the first liquid crystal layer is emitted through the first liquid crystal layer; when an electric field is applied to the first liquid crystal layer, ambient light incident on the first liquid crystal layer is incident on the optical film layer through the first liquid crystal layer and absorbed by the optical film layer; wherein the first rotation direction is opposite to the second rotation direction. In the direction away from the first liquid crystal layer, the optical film layer includes a first phase deviation film, a first sub-optical film layer, a second phase deviation film, a second sub-optical film layer and a reflective layer stacked sequentially; Both the first phase deviation film and the second phase deviation film are configured to deflect the phase of the transmitted light by π / 2; the optical axis of the first phase deviation film and the optical axis of the second phase deviation film are parallel to each other; the first sub-optical film layer is configured to allow light from the first phase deviation film to pass through when no electric field is applied to the first liquid crystal layer, and to deflect the phase of the light from the first phase deviation film by π / 2 when an electric field is applied to the first liquid crystal layer, and to absorb the light from the second sub-optical film; the second sub-optical film layer is configured to deflect the phase of the transmitted light by π / 2 when no electric field is applied to the first liquid crystal layer, and to prevent the polarization direction of the transmitted light from changing when an electric field is applied to the first liquid crystal layer.

2. The display substrate according to claim 1, characterized in that, The first sub-optical film layer includes a polarizing film; in the direction from the first liquid crystal layer to the optical film layer, the transmission axis of the polarizing film is deflected by 45° relative to the optical axis of the first phase deviation film along the second rotation direction.

3. The display substrate according to claim 1, characterized in that, The second sub-optical film layer includes a second liquid crystal layer, which includes nematic liquid crystal molecules; when no electric field is applied to the second liquid crystal layer, the orientation of the liquid crystal molecules in the second liquid crystal layer is parallel to the optical axis of the first phase deviation film.

4. The display substrate according to claim 3, characterized in that, The optical film layer further includes a first electrode located on the side of the second liquid crystal layer facing the first liquid crystal layer, the material of the reflective layer is a conductive material, and the reflective layer includes a second electrode; one of the first electrode and the second electrode is a pixel electrode, and the other is a common electrode.

5. The display substrate according to claim 3, characterized in that, The optical film layer further includes a first electrode located on the side of the second liquid crystal layer facing the first liquid crystal layer, and a second electrode located on the side of the second liquid crystal layer away from the first liquid crystal layer. The reflective layer is located on the side of the second electrode away from the first liquid crystal layer. The materials of the first electrode and the second electrode are light-transmitting materials.

6. The display substrate according to claim 1, characterized in that, In the direction from the optical film layer to the first liquid crystal layer, the first rotation direction is clockwise and the second rotation direction is counterclockwise.

7. The display substrate according to claim 1, characterized in that, In the direction from which the optical film layer points to the first liquid crystal layer, the first rotation direction is counterclockwise, and the second rotation direction is clockwise.

8. The display substrate according to claim 1, characterized in that, The cholesteric liquid crystal molecules have a variety of different pitches, and the range of pitches is as follows: nm~ nm; where n o n is the refractive index of the cholesteric liquid crystal molecule for ordinary light. e The cholesteric liquid crystal molecule has an unusual light refractive index.

9. The display substrate according to claim 8, characterized in that, The first liquid crystal layer includes nematic liquid crystal molecules and chiral polymerizable monomers. The concentration of chiral polymerizable monomers in the region with large pitch in the first liquid crystal layer is less than the concentration of chiral polymerizable monomers in the region with small pitch.

10. The display substrate according to claim 1, characterized in that, The display substrate further includes a color filter layer located on the side of the first liquid crystal layer opposite to the optical film layer, and the color filter layer includes at least three different color filter portions.

11. The display substrate according to claim 1, characterized in that, The cholesteric liquid crystal molecules have a pitch; the optical film layer includes a second liquid crystal layer, and the display substrate further includes a color filter layer located on the side of the second liquid crystal layer facing the first liquid crystal layer, the color filter layer including a color filter portion of one color.

12. A display device, characterized in that, The display device includes the display substrate according to any one of claims 1 to 11.

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