A display panel, display device

Abstract

The application provides a display panel and a display device, and relates to the technical field of display, and the display panel comprises a first polarization unit, a reflection unit arranged on the light-incident side of the first polarization unit, and at least one liquid crystal unit arranged between the first polarization unit and the reflection unit; the liquid crystal unit comprises a liquid crystal layer, liquid crystals in the liquid crystal layer have birefringence and optical activity, and the total equivalent retardation range of the liquid crystals in all the liquid crystal units comprises 100-441 nm. The display panel provided by the application can realize clear color display, and has the advantages of high reflectivity, fast response time, high refresh rate and the like.

Description

Technical Field

[0001] This application relates to the field of display technology, and more particularly to a display panel and a display device. Background Technology

[0002] Reflective display devices have great potential for development in fields such as smart wearables, e-books, and electronic price tags due to their advantages such as eye protection and low power consumption. However, current reflective display devices often suffer from drawbacks when displaying colors, including limited color achievable colors, long response times, high sensitivity to ambient temperature, and high costs, resulting in a poor user experience.

[0003] Therefore, there is an urgent need to provide a new type of reflective display device to solve the above problems. Summary of the Invention

[0004] The embodiments of this application adopt the following technical solutions:

[0005] On one hand, embodiments of this application provide a display panel, including:

[0006] First polarization unit;

[0007] A reflection unit is disposed opposite to the first polarization unit;

[0008] At least one liquid crystal cell is disposed between the first polarization cell and the reflection cell; the liquid crystal cell includes a liquid crystal layer, the liquid crystal in the liquid crystal layer has birefringence and optical rotation, and the total equivalent delay of the liquid crystal in all the liquid crystal cells ranges from 100 to 441 nm.

[0009] Optionally, the torsion angle of the liquid crystal in the liquid crystal layer of each liquid crystal cell ranges from 0 to 90°.

[0010] Optionally, the liquid crystal in the liquid crystal layer of each liquid crystal cell is a cholesteric liquid crystal;

[0011] Each of the liquid crystal units further includes two oppositely disposed electrodes, with the cholesteric liquid crystal located between the two oppositely disposed electrodes.

[0012] Optionally, the display panel includes at least a first liquid crystal unit and a second liquid crystal unit, wherein the first liquid crystal unit is disposed between the first polarizing unit and the second liquid crystal unit, and the second liquid crystal unit is disposed between the first liquid crystal unit and the reflective unit;

[0013] The first liquid crystal unit includes a first liquid crystal layer, and the second liquid crystal unit includes a second liquid crystal layer. The equivalent delay of the first liquid crystal in the first liquid crystal layer is greater than the equivalent delay of the second liquid crystal in the second liquid crystal layer.

[0014] Optionally, the display panel includes the first liquid crystal unit and the second liquid crystal unit, wherein the equivalent delay of the first liquid crystal in the first liquid crystal layer ranges from 200 to 400 nm;

[0015] The equivalent delay of the second liquid crystal in the second liquid crystal layer ranges from 100 to 200 nm.

[0016] Optionally, the equivalent optical axis direction of the first liquid crystal in the first liquid crystal layer is the same as the equivalent optical axis direction of the second liquid crystal in the second liquid crystal layer, and the angle between the first liquid crystal and the transmission axis of the first polarization unit is in the range of 42-48°.

[0017] Optionally, the first liquid crystal in the first liquid crystal layer has a first twist angle, and the second liquid crystal in the second liquid crystal layer has a second twist angle, wherein one of the first twist angle and the second twist angle has a twist angle range of 0-34° and the other twist angle has a twist angle range of 89-90°.

[0018] Optionally, the thickness of the first liquid crystal cell along the direction perpendicular to the first polarization cell is greater than the thickness of the second liquid crystal cell along the direction perpendicular to the first polarization cell.

[0019] Optionally, the first liquid crystal unit further includes a first substrate and a second substrate, the first substrate and the second substrate being disposed opposite to each other, the first substrate including a first electrode, the second substrate including a second electrode, and the first liquid crystal layer being disposed between the first electrode and the second electrode; the second liquid crystal unit further includes a third substrate and a fourth substrate, the third substrate and the fourth substrate being disposed opposite to each other, the third substrate including a third electrode, the fourth substrate including a fourth electrode, and the second liquid crystal layer being disposed between the third electrode and the fourth electrode;

[0020] The first electrode and the second electrode are configured to have a first voltage difference, and the third electrode and the fourth electrode are configured to have a second voltage difference. When either the first voltage difference or the second voltage difference is not zero, the total equivalent delay of the first liquid crystal in the first liquid crystal layer and the second liquid crystal in the second liquid crystal layer is less than the total equivalent delay of the first liquid crystal in the first liquid crystal layer and the second liquid crystal in the second liquid crystal layer when both the first voltage difference and the second voltage difference are zero.

[0021] Optionally, when the first voltage difference is configured to be at a first fixed value and the second voltage difference is configured to vary within a first preset range, the equivalent delay of the first liquid crystal in the first liquid crystal layer ranges from 200 to 400 nm; and the equivalent delay of the second liquid crystal in the second liquid crystal layer ranges from 130 to 154 nm.

[0022] Optionally, the first fixed value range includes 0-6V; the first preset range includes 0-10V.

[0023] Optionally, when the second voltage difference is configured to be at a second fixed value and the first voltage difference is configured to vary within a second preset range, the equivalent delay of the first liquid crystal in the first liquid crystal layer ranges from 240 to 275 nm; and the equivalent delay of the second liquid crystal in the second liquid crystal layer ranges from 100 to 200 nm.

[0024] Optionally, the second fixed value range includes 0-10V; the second preset range includes 0-10V.

[0025] Optionally, the display panel includes a third liquid crystal unit disposed between the first polarization unit and the reflection unit;

[0026] The display panel further includes a second polarization unit, which is disposed on the side of the reflective unit closer to the third liquid crystal unit, or the second polarization unit is disposed on the side of the reflective unit away from the third liquid crystal unit;

[0027] The third liquid crystal unit includes a third liquid crystal layer, and the equivalent delay of the third liquid crystal in the third liquid crystal layer ranges from 321 to 441 nm.

[0028] Optionally, the third liquid crystal unit further includes a fifth substrate and a sixth substrate, the fifth substrate and the sixth substrate being disposed opposite to each other, the fifth substrate including a fifth electrode, the sixth substrate including a sixth electrode, and the third liquid crystal layer being disposed between the fifth electrode and the sixth electrode;

[0029] The fifth electrode and the sixth electrode are configured to have a third voltage difference, the third voltage difference ranging from 0 to 6V.

[0030] Optionally, the transmission axis of the second polarization unit is not parallel to the transmission axis of the first polarization unit.

[0031] Optionally, the transmission axis of the second polarization unit is perpendicular to the transmission axis of the first polarization unit.

[0032] Optionally, the display panel further includes an absorption unit configured to absorb light parallel to the transmission axis of the second polarization unit;

[0033] When the second polarization unit is disposed on the side of the reflective unit closer to the third liquid crystal unit, the absorption unit is disposed on the side of the reflective unit away from the second polarization unit; when the second polarization unit is disposed on the side of the reflective unit away from the third liquid crystal unit, the absorption unit is disposed on the side of the second polarization unit away from the reflective unit.

[0034] Optionally, the absorption unit includes black ink or a third polarization unit, wherein the transmission axis of the third polarization unit is perpendicular to the transmission axis of the second polarization unit.

[0035] On the other hand, embodiments of this application provide a display device including the display panel described above.

[0036] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the structure of a display panel provided in an embodiment of this application;

[0039] Figure 2 This is a schematic diagram of another display panel structure provided in an embodiment of this application;

[0040] Figure 3 for Figure 1 The diagram shows the display principle of the display panel.

[0041] Figure 4 This is a schematic diagram of the display principle of a TN liquid crystal.

[0042] Figure 5 for Figure 1 The diagram shows a schematic of one POL absorption axis direction of the display panel.

[0043] Figure 6 for Figure 1 The diagram shown illustrates one type of rubbing orientation of liquid crystal in a display panel.

[0044] Figure 7 for Figure 1 A schematic diagram showing another Rubbing orientation of liquid crystal in the display panel;

[0045] Figure 8 for Figure 1 The diagram shown illustrates the first color coordinate of the display panel.

[0046] Figure 9 for Figure 1 The diagram shows the second color coordinate of the display panel.

[0047] Figure 10 for Figure 1 The diagram shows one possible result of LC1 being loaded with 6V and LC2 being loaded with 0→6V voltage in the display panel shown.

[0048] Figure 11 for Figure 1 The diagram shows another possible result of LC1 being loaded with 6V and LC2 being loaded with 0→6V in the display panel shown.

[0049] Figure 12 for Figure 1 The diagram shows another possible result of applying 0→6V voltage to LC1 and LC2 in the display panel shown.

[0050] Figure 13 for Figure 1 The diagram shows the absorption axis direction of another type of POL in the display panel.

[0051] Figure 14 for Figure 1 The diagram shows another Rubbing orientation of the liquid crystal in the display panel.

[0052] Figure 15 for Figure 1 The diagram shows another Rubbing orientation of the liquid crystal in the display panel.

[0053] Figure 16 for Figure 1 The diagram shows the third color coordinates of the display panel.

[0054] Figure 17 for Figure 1 The diagram shows the fourth color coordinate of the display panel.

[0055] Figure 18 for Figure 1 The diagram shows the fifth color coordinate of the display panel.

[0056] Figure 19 for Figure 1 The diagram shows one possible result of LC2 being loaded with 6V and LC1 being loaded with 0→6V voltage in the display panel shown.

[0057] Figure 20 for Figure 1 The diagram shows another possible result of LC2 being loaded with 6V and LC1 being loaded with 0→6V in the display panel shown.

[0058] Figure 21 for Figure 1 The diagram shows one possible result of applying a 0→10V voltage to LC2 and a 0→10V voltage to LC1 in the display panel shown.

[0059] Figure 22 for Figure 2 The diagram shown illustrates the principle of the display panel in its illuminated state.

[0060] Figure 23 for Figure 2 The diagram shown illustrates the principle of the display panel displaying a dark state.

[0061] Figure 24 for Figure 2 The diagram shows the absorption axis direction of the POL in the display panel.

[0062] Figure 25 for Figure 2 The diagram shows the Rubbing orientation of the display panel.

[0063] Figure 26 for Figure 2 The diagram shown illustrates a color coordinate system for a display panel.

[0064] Figure 27 for Figure 2 Another color coordinate diagram of the display panel shown. Detailed Implementation

[0065] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0066] For clarity, the thickness of regions and layers may be exaggerated in the figures. The same reference numerals in the figures denote the same or similar structures, and therefore their detailed descriptions are omitted. Furthermore, the figures are merely illustrative of this application and are not necessarily drawn to scale.

[0067] In the embodiments of this application, unless otherwise stated, "a plurality of" means two or more; the orientation or positional relationship indicated by the term "above" is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing this application and simplifying the description, and is not intended to indicate or imply that the structure or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0068] Unless the context otherwise requires, throughout the specification and claims, the term "comprising" is interpreted as open-ended and encompassing, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "example," "specific example," or "some examples" are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this application. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific feature, structure, material, or characteristic may be included in any suitable manner in any one or more embodiments or examples.

[0069] In the embodiments of this application, the terms "first", "second", "third", "fourth", "fifth", and "sixth" are used to distinguish identical or similar items with essentially the same function and effect. This is only for the purpose of clearly describing the technical solution of the embodiments of this application, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0070] Reflective display devices, due to their advantages such as eye protection and low power consumption, have great development potential in fields such as smart wearables, e-books, electronic price tags, and electronic billboards. Reflective LCD (Liquid Crystal Display) is one such type. Reflective LCD displays offer many advantages, such as: they can use natural ambient light, demonstrating the ability of liquid crystals to display clear images with extremely low power consumption; their brightness depends on ambient light, making them more easily tolerated by the human eye, thus providing eye protection; and they can operate without backlighting, resulting in a thinner, lighter, and more portable design.

[0071] Currently, reflective display devices on the market mainly include E-Ink (electronic ink screen) and RLCD (Reflective Liquid Crystal Display), but they are currently mainly focused on monochrome displays. E-Ink color displays are mainly achieved through color electronic ink, but the range of colors that can be achieved is currently limited (generally only black-and-white red and black-and-white red-and-yellow). At the same time, electronic ink screens have a long response time (approximately ~100ms), resulting in severe ghosting of written characters, and the ink has high requirements for the ambient temperature (0-70℃), which seriously affects the customer experience.

[0072] RLCD color displays have a short response time and low requirements for ambient temperature (-30~80℃), but require the use of special POLs (Polarizers), such as POLs with scattering films, which increases costs. At the same time, color displays require an additional CF (Color Filtration), which has a significant loss of reflectivity, resulting in increased costs and a loss of reflectivity, leading to poor display quality.

[0073] Based on the above, embodiments of this application provide a display panel, see reference. Figure 1 and Figure 2 As shown, the display panel includes:

[0074] First polarization unit 1.

[0075] The reflection unit 2 is positioned opposite to the first polarization unit 1.

[0076] At least one liquid crystal cell 3 is disposed between the first polarization cell 1 and the reflection cell 2; the liquid crystal cell 3 includes a liquid crystal layer, the liquid crystal in the liquid crystal layer has birefringence and optical rotation, and the total equivalent delay of the liquid crystal in all liquid crystal cells ranges from 100 to 441 nm.

[0077] The type of display panel is not specifically limited here. For example, the display panel may include an LCD display panel. Further optionally, the display panel may include an RLCD display panel.

[0078] The material and type of the first polarization unit are not specifically limited here. For example, the material of the first polarization unit may include PVA (polyvinyl alcohol), PVC (polyvinyl chloride), TAC (cellulose triacetate), etc.; the type of the first polarization unit may include a linear polarizer, a grating, etc. Further optionally, the first polarization unit may include TAC, PVA, TAC and PSA (pressure-sensitive adhesive) stacked in sequence. It should be noted that the first polarization unit 1 can be abbreviated as POL1.

[0079] The material and type of the above-mentioned reflective unit are not specifically limited here. For example, the above-mentioned reflective unit may include a film layer that can reflect visible light, such as a metal reflective layer, an APF (Advanced Polarizer Film) film, etc.

[0080] The statement that the above-mentioned display panel includes at least one liquid crystal unit means that the above-mentioned display panel includes one liquid crystal unit; or, the above-mentioned display panel includes multiple liquid crystal units, depending on the actual application.

[0081] The structure of the liquid crystal unit is not specifically limited here. For example, the liquid crystal unit may include an upper substrate and a lower substrate disposed opposite each other, and a liquid crystal layer disposed in the upper substrate and the lower substrate.

[0082] The type of liquid crystal in the liquid crystal layer is not specifically limited here. For example, the liquid crystal in the liquid crystal layer can be a TN (Twist Nematic) liquid crystal.

[0083] The total equivalent delay of the liquid crystal in all the above liquid crystal cells is not specifically limited here. For example, the total equivalent delay of the liquid crystal in all the above liquid crystal cells can be 100nm, 200nm, 300nm, 400nm or 441nm, etc.

[0084] The aforementioned birefringence refers to the phenomenon where incident light (visible light) enters a liquid crystal cell. Due to the different refractive indices (Δn) of the liquid crystal for different frequencies of light, the propagation directions of different colors of light are deflected to varying degrees, causing the incident light to disperse after leaving the liquid crystal cell, i.e., dispersion occurs. This dispersion effect results in different amounts of visible light of different wavelengths being emitted after the incident light passes through the liquid crystal cell and the reflecting cell, leading to color shift. This allows for color display. If a certain wavelength band of visible light is emitted in greater quantities, the corresponding color will be displayed. For example, if there is a high emission of light near 550nm and a low emission of light in other wavelength bands, the display will be greenish; if there is a low emission of light in wavelengths below 400nm and a high emission of light in other wavelength bands, the display will be yellowish. Taking TN liquid crystal as an example, there are many factors that affect the dispersion effect of TN liquid crystal cell (liquid crystal cell), such as: LCTwist Angle, Rubbing direction, thickness of liquid crystal cell along the direction perpendicular to the first polarization unit (liquid crystal cell thickness), operating voltage, transmission axis / absorption axis angle of the first polarization unit, etc.

[0085] The aforementioned optical rotation refers to the fact that when no electricity is applied to the liquid crystal or a low voltage (a voltage that allows the liquid crystal to be in a non-vertical state), the polarization direction of the incident light changes with the optical axis of the liquid crystal; while when a high voltage is applied to the liquid crystal (a voltage that allows the liquid crystal to be in a vertical state), the liquid crystal molecules stand upright, and the polarization direction of the incident light does not change.

[0086] An embodiment of this application provides a display panel, which includes: a first polarization unit; a reflection unit disposed opposite to the first polarization unit; and at least one liquid crystal unit disposed between the first polarization unit and the reflection unit. The liquid crystal unit includes a liquid crystal layer, wherein the liquid crystal in the liquid crystal layer has birefringence and optical rotation, and the total equivalent delay of the liquid crystal in all liquid crystal units ranges from 100 to 441 nm.

[0087] Since the liquid crystals in all the aforementioned liquid crystal units can be equivalent to 1 / 4 to 1 / 2 waveplates, these 1 / 4 to 1 / 2 waveplates can modulate the polarization state of visible light (wavelength range of 380 to 780 nm). When visible light shines on the display panel provided in this application embodiment, light in the range of approximately 380 / 4 to 780 / 2 nm (i.e., approximately 95 to 390 nm) can be seen by the human eye. Combined with the birefringence and optical rotation properties of liquid crystals, when visible light shines on the display panel provided in this application embodiment with a total equivalent delay range of 100-441 nm, the human eye can see a clear color display image. However, when light with a wavelength of 360 nm shines on the display panel, the human eye may not be able to see the display, or may hardly see the color display. Thus, this application provides a novel reflective display panel that does not require a color filter or a specially structured first polarization unit; color display can be achieved using only a conventionally structured first polarization unit and liquid crystal units. On the one hand, since no color filter is needed, the reflective display panel has high reflectivity and clear color display. On the other hand, since no special first polarization unit is needed, the structure and process of the reflective display panel are relatively simple, resulting in lower cost. Furthermore, the reflective display panel has a fast response time (estimated to be ~40ms) and a high refresh rate, reducing or even eliminating ghosting issues. Moreover, the reflective display panel has high environmental reliability and can operate within a wide temperature range (e.g., -30 to 80℃), making it suitable for a wide range of applications.

[0088] Optionally, refer to Figure 1 and Figure 2 As shown, the torsion angle range of the liquid crystal in the liquid crystal layer 3 of each liquid crystal unit includes 0-90°. Therefore, by controlling the torsion angle of the liquid crystal in each liquid crystal layer, the equivalent Δn, equivalent Re, etc. of the liquid crystal can be affected, thereby enabling the reflective display panel to achieve better color display.

[0089] The torsion angle of the liquid crystal in the liquid crystal layer of each of the above liquid crystal units is not specifically limited here. For example, the torsion angle of the liquid crystal in the liquid crystal layer of each of the above liquid crystal units can be 0°, 45°, 60°, 80° or 90°, etc.

[0090] The fabrication process for the torsion angle of the liquid crystal in the liquid crystal layer of each of the above-mentioned liquid crystal units is not specifically limited here. For example, the torsion angle of the liquid crystal can be achieved by performing initial rubbing alignment on the upper and lower substrates on both sides of the liquid crystal layer. Taking a torsion angle of 90° in the liquid crystal layer of each liquid crystal unit as an example, the rubbing direction of the upper substrate on one side of the liquid crystal layer can be 45° and the rubbing direction of the lower substrate on the other side of the liquid crystal layer can be -45° to achieve a torsion angle of 90°.

[0091] Optionally, the liquid crystal in the liquid crystal layer of each liquid crystal unit is a cholesteric liquid crystal; each liquid crystal unit also includes two oppositely disposed electrodes, with the cholesteric liquid crystal located between the two oppositely disposed electrodes.

[0092] The aforementioned cholesteric liquid crystal has a helical structure. The molecules of the cholesteric liquid crystal can be layered and twisted, with each layer parallel to the others. When no voltage is applied or a low voltage is applied, the cholesteric liquid crystal in each layer lies flat within the layer; when a high voltage is applied, it stands vertically within the layer. The cholesteric liquid crystal exhibits selective reflection, obeying Bragg's law of reflection: the reflection center wavelength L = n × P0, and the reflection width ΔL = Δn × P0, where P0 is the pitch of the liquid crystal. By adjusting the pitch of the cholesteric liquid crystal to make its reflection wavelength fall within the visible light range, the cholesteric liquid crystal will display color in a planar texture. Therefore, the display panel provided in this application embodiment is a TN display panel, i.e., a twisted nematic liquid crystal display panel. By applying voltage to the electrodes on both sides of the cholesteric liquid crystal, different states of the cholesteric liquid crystal can be controlled to achieve different color displays.

[0093] Optionally, refer to Figure 1 As shown, the display panel includes at least a first liquid crystal unit 31 and a second liquid crystal unit 32. The first liquid crystal unit 31 is disposed between the first polarization unit 1 and the second liquid crystal unit 32, and the second liquid crystal unit 32 is disposed between the first liquid crystal unit 31 and the reflection unit 2. The first liquid crystal unit 31 includes a first liquid crystal layer, and the second liquid crystal unit 32 includes a second liquid crystal layer. The equivalent delay of the first liquid crystal LC1 in the first liquid crystal layer is greater than the equivalent delay of the second liquid crystal LC2 in the second liquid crystal layer.

[0094] The statement that the display panel includes at least a first liquid crystal unit and a second liquid crystal unit means that the display panel includes both a first liquid crystal unit and a second liquid crystal unit; or, the display panel may include other liquid crystal units besides the first and second liquid crystal units, without specific limitations. For example, the display panel may include three liquid crystal units, such as a first liquid crystal unit, a second liquid crystal unit, and a fourth liquid crystal unit. The fourth liquid crystal unit may be disposed between the first and second liquid crystal units; or, the fourth liquid crystal unit may be disposed on the side of the first liquid crystal unit away from the second liquid crystal unit; or, the fourth liquid crystal unit may be disposed on the side of the second liquid crystal unit away from the first liquid crystal unit. The fourth liquid crystal unit includes a fourth liquid crystal layer. The equivalent retardation of the fourth liquid crystal in the fourth liquid crystal layer may be the same as the equivalent retardation of the first liquid crystal in the first liquid crystal layer; or, the equivalent retardation of the fourth liquid crystal in the fourth liquid crystal layer may be the same as the equivalent retardation of the second liquid crystal in the second liquid crystal layer; or, the equivalent retardation of the fourth liquid crystal in the fourth liquid crystal layer may be different from both the equivalent retardation of the first and second liquid crystals in the first and second liquid crystal layers, without specific limitations.

[0095] The structure of the first liquid crystal unit is not specifically limited here. For example, the first liquid crystal unit may include a first substrate and a second substrate disposed opposite to each other, and a first liquid crystal layer disposed between the first substrate and the second substrate.

[0096] The structure of the second liquid crystal unit is not specifically limited here. For example, the second liquid crystal unit may include a third substrate and a fourth substrate disposed opposite to each other, and a second liquid crystal layer disposed between the third substrate and the fourth substrate.

[0097] It should be noted that the first liquid crystal unit and the second liquid crystal unit can share a substrate, that is, the second substrate and the third substrate can be a single substrate.

[0098] In the display panel provided in this application embodiment, the equivalent retardation of the first liquid crystal in the first liquid crystal layer is greater than the equivalent retardation of the second liquid crystal in the second liquid crystal layer. Since liquid crystals have a regulating effect on visible light of different wavelengths, this regulating effect is related to the equivalent retardation of the liquid crystal. Specifically: when the equivalent retardation of the liquid crystal is low, for example, 100nm, it is effective for low-band visible light, increasing the emission of low-band light, thus enabling the display panel to achieve a bluish color; when the equivalent retardation of the liquid crystal is high, for example, 400nm, it is effective for high-band visible light, increasing the emission of high-band light, thus enabling the display panel to achieve a reddish color; when the equivalent retardation of the liquid crystal is in the middle range, it is effective for mid-band visible light, increasing the emission of mid-band light, thus enabling the display panel to achieve a yellowish-green color. That is, the display panel provided in this application embodiment can influence the equivalent Δn, equivalent Re, etc. of the liquid crystal by controlling the relationship between the equivalent delay of the liquid crystal in the liquid crystal layer of at least two liquid crystal cells, thereby enabling the reflective display panel to achieve better and more color display.

[0099] Optionally, refer to Figure 1 As shown, the display panel includes a first liquid crystal unit 31 and a second liquid crystal unit 32. The equivalent retardation range of the first liquid crystal LC1 in the first liquid crystal layer is 200-400nm; the equivalent retardation range of the second liquid crystal LC2 in the second liquid crystal layer is 100-200nm. This allows the first liquid crystal in the first liquid crystal layer to be effective for mid-wavelength and high-wavelength visible light, enabling the display panel to achieve various colors such as yellowish-green and reddish hues. Similarly, it allows the second liquid crystal in the second liquid crystal layer to be effective for mid-wavelength and low-wavelength visible light, enabling the display panel to achieve various colors such as yellowish-green and bluish hues. In other words, by controlling the equivalent retardation of the liquid crystal in the liquid crystal layer of each liquid crystal unit, the equivalent Δn and equivalent Re of the liquid crystal can be affected, thereby enabling the reflective display panel to achieve better color display.

[0100] The equivalent delay of the first liquid crystal in the first liquid crystal layer is not specifically limited here. For example, the equivalent delay of the first liquid crystal in the first liquid crystal layer can be 200nm, 250nm, 300nm, 350nm or 400nm, etc.

[0101] The equivalent delay of the second liquid crystal in the second liquid crystal layer is not specifically limited here. For example, the equivalent delay of the second liquid crystal in the second liquid crystal layer can be 100nm, 130nm, 150nm, 180nm or 200nm, etc.

[0102] Optionally, refer to Figure 1As shown, the equivalent optical axis direction of the first liquid crystal LC1 in the first liquid crystal layer is the same as that of the second liquid crystal LC2 in the second liquid crystal layer, and the angle between both and the transmission axis of the first polarization unit 1 ranges from 42° to 48°. Therefore, by controlling the relationship between the equivalent optical axis directions of the liquid crystals in the liquid crystal layers of the two liquid crystal units, and the angle between the equivalent optical axis directions and the transmission axis of the first polarization unit, the equivalent Δn and equivalent Re of the liquid crystals can be affected, thereby enabling the reflective display panel to achieve better color display.

[0103] The equivalent optical axis of a liquid crystal is the midpoint between the Rubbing directions of the two substrates (upper and lower substrates) when the liquid crystal is in an unpowered state. In other words, the angle between the upper and lower substrates with respect to the liquid crystal alignment direction is the liquid crystal's twist angle, and the axis at half the twist angle is the equivalent optical axis. Even when the liquid crystal is powered on, its equivalent optical axis remains unchanged. Specifically, the equivalent optical axis of the first liquid crystal in the first liquid crystal layer is the midpoint between the Rubbing directions of the first and second substrates in the first liquid crystal unit. Similarly, the equivalent optical axis of the second liquid crystal in the second liquid crystal layer is the midpoint between the Rubbing directions of the third and fourth substrates in the second liquid crystal unit.

[0104] Here, the angle between the equivalent optical axis of the first liquid crystal in the first liquid crystal layer and the transmission axis of the first polarization unit is not specifically limited. For example, the angle between the equivalent optical axis of the first liquid crystal in the first liquid crystal layer and the transmission axis of the first polarization unit can be 42°, 43°, 45°, 46°, 47° or 48°, etc.

[0105] Optionally, refer to Figure 1 As shown, the first liquid crystal LC1 in the first liquid crystal layer has a first twist angle, and the second liquid crystal LC2 in the second liquid crystal layer has a second twist angle. One of the first and second twist angles ranges from 0 to 34°, and the other twist angle ranges from 89 to 90°. Therefore, by controlling the liquid crystal twist angle in the liquid crystal layer of each liquid crystal unit, the equivalent Δn and equivalent Re of the liquid crystal can be affected, thereby enabling the reflective display panel to achieve better color display.

[0106] Here, no specific limitation is made on one of the torsion angles mentioned above, namely the first torsion angle and the second torsion angle. For example, one of the torsion angles mentioned above can be 0°, 5°, 10°, 20°, 26°, 30° or 34°, etc.

[0107] There is no specific limitation on the other torsion angle mentioned above. For example, the other torsion angle can be 89° or 90°, etc.

[0108] Optionally, refer to Figure 1 As shown, the thickness h1 of the first liquid crystal cell 31 along the direction perpendicular to the first polarization unit 1 is greater than the thickness h2 of the second liquid crystal cell 32 along the direction perpendicular to the first polarization unit 1. Therefore, by controlling the thickness of each liquid crystal cell, i.e., the cell thickness, the equivalent Δn and equivalent Re of the liquid crystal can be affected, thereby enabling the reflective display panel to achieve better color display.

[0109] Optionally, refer to Figure 1 As shown, the first liquid crystal unit 31 further includes a first substrate and a second substrate, which are disposed opposite to each other. The first substrate includes a first electrode, and the second substrate includes a second electrode. A first liquid crystal layer is disposed between the first electrode and the second electrode. The second liquid crystal unit 32 further includes a third substrate and a fourth substrate, which are disposed opposite to each other. The third substrate includes a third electrode, and the fourth substrate includes a fourth electrode. A second liquid crystal layer is disposed between the third electrode and the fourth electrode. The first electrode and the second electrode are configured to have a first voltage difference, and the third electrode and the fourth electrode are configured to have a second voltage difference. When either the first voltage difference or the second voltage difference is not zero, the total equivalent delay of the first liquid crystal LC1 in the first liquid crystal layer and the second liquid crystal LC2 in the second liquid crystal layer is less than the total equivalent delay of the first liquid crystal in the first liquid crystal layer and the second liquid crystal in the second liquid crystal layer when both the first voltage difference and the second voltage difference are zero.

[0110] The structure of the first substrate is not specifically limited here. For example, the first electrode or the like can be formed directly on the first substrate; or, the first substrate may include a substrate, and the first electrode or the like can be formed directly on the substrate, depending on the actual application. The structures of other substrates can be deduced similarly, and will not be elaborated here.

[0111] It should be noted that the first liquid crystal unit and the second liquid crystal unit can share a substrate, that is, the second substrate and the third substrate can be a single substrate.

[0112] The following example uses a TN LCD to illustrate how controlling the voltage in each liquid crystal cell can enable a reflective display panel to achieve better color display:

[0113] In the case of the first liquid crystal LC1 in the liquid crystal layer of the first liquid crystal unit and the second liquid crystal LC2 in the liquid crystal layer of the second liquid crystal unit, one liquid crystal has a twist angle close to 90° (large twist angle), and the other liquid crystal has a twist angle close to 0° (small twist angle). Combined with... Figure 1 and Figure 3As shown, when a TN liquid crystal is not powered or is subjected to a low voltage (a voltage sufficient to keep the liquid crystal in a non-vertical state), the polarization direction of the incident light changes along the optical axis of the liquid crystal. However, when a high voltage (a voltage sufficient to keep the liquid crystal in a vertical state) is applied, the liquid crystal molecules stand upright, and the polarization direction of the incident light does not change. Therefore, regardless of whether LC1 and LC2 are subjected to low or high voltage, the incident light will be emitted, causing the display panel to appear bright. Thus, under specific conditions such as LC twist angle, rubbing direction, and cell thickness, color display can be achieved by adjusting the voltages applied to LC1 and LC2. The voltages applied to LC1 and LC2 can be controlled independently; no specific limitations are imposed here.

[0114] Assuming the torsion angle of one of the liquid crystals in LC1 and LC2 is 90°, the main function of this liquid crystal cell is to utilize the optical rotation of TN liquid crystals to convert incident light into elliptically polarized light with its major axis approaching a certain direction. Therefore, regardless of the voltage applied to the other liquid crystal cell, a portion of the incident light can exit after passing through the liquid crystal cell and the reflecting unit, thus achieving color display. In this application, the liquid crystals in the liquid crystal layers of both liquid crystal cells are TN liquid crystals. Therefore, by utilizing their birefringence properties and applying different voltages to the liquid crystal layers of the two liquid crystal cells, their equivalent liquid crystal retardation (Re) can be different, resulting in different transmittance for different wavelengths of light. (Reference) Figure 4 As shown, when a TN liquid crystal is in an unpowered state, the liquid crystal molecules are arranged in a flat and helical pattern. At this time, the equivalent Δn of the liquid crystal molecules is relatively large, so the equivalent Re. of the liquid crystal cell is relatively large (Re. = Δn × d, where Δn is the refractive index of the liquid crystal and d is the cell thickness). As the voltage applied to the liquid crystal increases, the liquid crystal molecules gradually stand upright, the equivalent Δn decreases, and that is, the equivalent Re. decreases.

[0115] Equivalent Re(total) = Equivalent Re(LC1) + Equivalent Re(LC2). When the thickness of LC1 is greater than that of LC2, and both LC1 and LC2 are unpowered, the equivalent Re(LC1) is greater than the equivalent Re(LC2). LC1 can maintain the equivalent Re(total) at a higher level, while LC2 can maintain the equivalent Re(total) at a lower level. As the voltage applied to LC1 increases, the equivalent Re(LC1) decreases. Similarly, as the voltage applied to LC2 increases, the equivalent Re(LC2) decreases.

[0116] According to the principle of light transmittance of liquid crystals, when the equivalent total (Re) is large, more high-wavelength light is emitted, resulting in a reddish display. As the equivalent total (Re) decreases, more mid-wavelength light is emitted, resulting in a yellowish-green display. As the equivalent total (Re) continues to decrease, the amount of low-wavelength light emitted increases, resulting in a bluish display. For example, when LC1 is not powered or has a low voltage, the equivalent Re (LC1) is large. At this time, as the voltage applied to LC2 increases, the equivalent Re (LC2) decreases, and the equivalent total (Re) decreases, but both remain at a high level. Therefore, the RLCD displays colors from yellow to green. When LC1 is powered, the equivalent Re (LC1) is small or close to 0. At this time, as the voltage applied to LC2 increases, the equivalent total (Re) decreases. Therefore, the RLCD displays colors from red to blue. For example, when LC2 is not powered or has a low voltage, the equivalent Re.(LC2) is relatively large. At this time, as the voltage applied to LC1 increases, the equivalent Re.(LC1) decreases, and the equivalent Re.(total) decreases. Therefore, the RLCD displays a color from red to blue. When LC2 is powered by a high voltage, the equivalent Re.(LC2) is relatively small or close to 0. At this time, as the voltage applied to LC1 increases, the equivalent Re.(LC1) decreases, and the equivalent Re.(total) decreases. Moreover, the overall Re.(total) is lower than before. Therefore, the RLCD displays a color from green to blue.

[0117] Therefore, the reflective display panel provided in this application embodiment can achieve better color display by controlling the voltage of each liquid crystal cell to affect the equivalent Δn, equivalent Re, etc. of the liquid crystal.

[0118] Optionally, when the first voltage difference is configured to be at a first fixed value and the second voltage difference is configured to vary within a first preset range, the equivalent retardation of the first liquid crystal in the first liquid crystal layer ranges from 200 to 400 nm; and the equivalent retardation of the second liquid crystal in the second liquid crystal layer ranges from 130 to 154 nm. Thus, by changing the voltage of the liquid crystal in the liquid crystal layer of the second liquid crystal unit, the equivalent Δn, equivalent Re, etc., of the liquid crystal can be affected, thereby enabling the reflective display panel to achieve better color display.

[0119] The equivalent delay of the first liquid crystal in the first liquid crystal layer is not specifically limited here. For example, the equivalent delay of the first liquid crystal in the first liquid crystal layer can be 200nm, 250nm, 300nm, 350nm or 400nm.

[0120] The equivalent delay of the second liquid crystal in the second liquid crystal layer is not specifically limited here. For example, the equivalent delay of the second liquid crystal in the second liquid crystal layer can be 130nm, 135nm, 140nm, 145nm or 154nm.

[0121] Optionally, the first fixed value range includes 0-6V; the first preset range includes 0-10V.

[0122] The first fixed value mentioned above is not specifically limited here. For example, the first fixed value can be any value among 0V, 1V, 2V, 3V, 4V, 5V, or 6V, etc.

[0123] The following explains in detail how to achieve multiple color displays by controlling the voltage applied to the liquid crystal:

[0124] refer to Figures 5-7 As shown, the absorption axis of the first polarization unit is set to 135° (transmission axis 45°), and the LC1 TwistAngle is set to 90° (at this time, the first substrate, i.e. Figure 6 The rubbing direction of the upper substrate is 45°, and the second substrate, i.e. Figure 6 The rubbing direction of the lower substrate is -45°), and the LC2 Twist Angle is 0-26° (at this time, the third substrate, i.e. Figure 7 The Rubbing direction of the upper substrate is 0-13°, and the fourth substrate, i.e. Figure 7 The Rubbing direction of the lower substrate is 0 to -13°.

[0125] The absorption axis of the first polarization unit is defined as 135°, the LC1 TwistAngle as 90°, the LC2 TwistAngle as 0°, the equivalent retardation of LC1 as 270nm, and the equivalent retardation of LC2 as 140nm. Tests were conducted, and the results are as follows: When the voltage applied to LC1 is set to 0V (no power applied), the results are shown in Table 1 below. Figure 8 As shown, when the voltage applied to LC2 changes from 0 to 10V, the RLCD display color changes from yellow to green.

[0126] Table 1

[0127]

[0128] In Table 1 above, Ref. represents the reflectivity of the display panel.

[0129] When the voltage applied to LC1 is set to 6V (high voltage), as shown in Table 2 below. Figure 9 As shown, when the voltage applied to LC2 changes from 0 to 10V, the RLCD display color changes from red to blue.

[0130] Table 2

[0131]

[0132] In Table 2 above, Ref. represents the reflectivity of the display panel.

[0133] refer to Figures 10-12 As shown, the absorption axis of the first polarization unit is set to 135° (transmission axis 45°), the LC1 Twist Angle is set to 90° (at this time, the rubbing direction of the first substrate is 45° and the rubbing direction of the second substrate is -45°), the LC2 Twist Angle is set to 0-26° (at this time, the rubbing direction of the third substrate is 0-13° and the rubbing direction of the fourth substrate is 0--13°), the equivalent retardation range of LC1 is 200-400nm, and the equivalent retardation range of LC2 is 130-154nm.

[0134] The test results were as follows: when the voltage applied to LC1 is set to <2V (no power or low voltage), and the voltage applied to LC2 is changed from 0 to 10V, the RLCD display color changes from yellow to green; when the voltage applied to LC1 is set to ≥2V (high voltage), and the voltage applied to LC2 is changed from 0 to 10V, the RLCD display color changes from blue to red.

[0135] It should be noted that the angle of the liquid crystal in the liquid crystal layer of the first polarization unit and the liquid crystal unit can be rotated and changed, as long as the relative relationship is maintained, and it is not limited to a specific angle.

[0136] Optionally, when the second voltage difference is configured to be at a second fixed value and the first voltage difference is configured to vary within a second preset range, the equivalent retardation of the first liquid crystal in the first liquid crystal layer ranges from 240 to 275 nm; and the equivalent retardation of the second liquid crystal in the second liquid crystal layer ranges from 100 to 200 nm. Thus, by controlling the equivalent retardation of the liquid crystals in the liquid crystal layers of the two liquid crystal units, the equivalent Δn, equivalent Re, etc., of the liquid crystals can be affected, thereby enabling the reflective display panel to achieve better color display.

[0137] The equivalent delay of the first liquid crystal in the first liquid crystal layer is not specifically limited here. For example, the equivalent delay of the first liquid crystal in the first liquid crystal layer can be 240nm, 250nm, 260nm or 275nm, etc.

[0138] The equivalent delay of the second liquid crystal in the second liquid crystal layer is not specifically limited here. For example, the equivalent delay of the second liquid crystal in the second liquid crystal layer can be 100nm, 130nm, 170nm or 200nm, etc.

[0139] Optionally, the second fixed value range includes 0-10V; the second voltage difference range includes 0-10V.

[0140] The second fixed value is not specifically limited here. For example, the second fixed value can be any value among 0V, 2V, 4V, 5V, 6V, 8V, or 10V, etc.

[0141] The following explains in detail how to achieve multiple color displays by controlling the voltage applied to the liquid crystal:

[0142] refer to Figures 13-15 As shown, the absorption axis of the first polarization unit is set to 135° (transmission axis 45°), and the LC1 TwistAngle is 0~34° (at this time, the first substrate, i.e. Figure 14 The rubbing direction of the upper substrate is 0–17°; the second substrate, i.e. Figure 14 The rubbing direction of the lower substrate is 0 to -17°, and the LC2 Twist Angle is 90° (at this time, the rubbing of the third substrate, i.e., Figure 15 The upper substrate is oriented at 45°; the fourth substrate, i.e. Figure 15 The Rubbing direction of the lower substrate is -45°.

[0143] The absorption axis of the first polarization unit is defined as 135°, the LC1 Twist Angle as 20° (at which point the rubbing direction of the first substrate is 10°; the rubbing direction of the second substrate is -10°), the LC2 Twist Angle as 90°, the equivalent delay of LC1 as 270nm, and the equivalent delay of LC2 as 140nm. Tests were conducted, and the results are as follows: when the voltage applied to LC2 is set to 0V (no power applied), the results are shown in Table 3 below. Figure 16 As shown, when the voltage applied to LC1 changes from 0 to 10V, the RLCD display color changes from red to blue.

[0144] Table 3

[0145]

[0146] In Table 3 above, Ref. represents the reflectivity of the display panel.

[0147] When the voltage applied to LC2 is set to 3V (low voltage), as shown in Table 4 below. Figure 17 As shown, when the voltage applied to LC1 changes from 0 to 10V, the RLCD display color changes from yellow to blue.

[0148] Table 4

[0149]

[0150] In Table 4 above, Ref. represents the reflectivity of the display panel.

[0151] When the voltage applied to LC2 is set to 10V (high voltage), as shown in Table 5 below and Figure 18 as shown, when the voltage applied to LC1 is changed from 0 → 10V, the color shown on the RLCD changes from green → blue.

[0152] Table 5

[0153]

[0154] In Table 5 above, Ref. represents the reflectivity of the display panel.

[0155] Reference Figures 19-21 As shown, the absorption axis of the first polarizing unit is set to 135° (transmission axis 45°), LC1 TwistAngle is 0 - 34° (at this time, the rubbing direction of the first substrate is 0 - 17°; the rubbing direction of the second substrate is 0 - -17°), LC2 TwistAngle is 90°, the equivalent retardation range of LC1 is 240 - 275nm, and the equivalent retardation range of LC2 is 100 - 200nmnm.

[0156] Testing this gives the results: when the voltage applied to LC2 is set to ≤ 2V (no power or low voltage), when the voltage applied to LC1 is changed from 0 → 10V, the color shown on the RLCD changes from red → blue; when 2V < the voltage applied to LC2 ≤ 5V (medium voltage), when the voltage applied to LC1 is changed from 0 → 10V, the color shown on the RLCD changes from yellow → blue; when the voltage applied to LC2 > 5V (high voltage), when the voltage applied to LC1 is changed from 0 → 10V, the color shown on the RLCD changes from green → blue.

[0157] The angles of the liquid crystals in the liquid crystal layer of the above first polarizing unit and liquid crystal unit can be rotated and changed, as long as the relative relationship is ensured, and it can be not limited to a certain specific angle.

[0158] Optionally, referring to Figure 2 、 Figures 22-23 as shown, the display panel includes a third liquid crystal unit 33, and the third liquid crystal unit 33 is arranged between the first polarizing unit 1 and the reflection unit 2; the display panel also includes a second polarizing unit 4.

[0159] Reference Figure 22 and Figure 23 as shown, the second polarizing unit 4 is arranged on the side of the reflection unit 2 close to the third liquid crystal unit 33. Alternatively, referring to Figure 2 as shown, the second polarizing unit 4 is arranged on the side of the reflection unit 2 away from the third liquid crystal unit 33.

[0160] Reference Figure 2 、 Figures 22-23As shown, the third liquid crystal unit 33 includes a third liquid crystal layer, and the equivalent delay of the third liquid crystal LC3 in the third liquid crystal layer ranges from 321 to 441 nm.

[0161] The structure of the third liquid crystal unit is not specifically limited here. For example, the third liquid crystal unit may include a fifth substrate and a sixth substrate disposed opposite to each other, and a third liquid crystal layer disposed between the fifth substrate and the sixth substrate.

[0162] The aforementioned first polarization unit has a first transmission axis, and when it is configured such that when incident light rays are directed toward the first polarization unit, polarized light with a polarization direction parallel to the first transmission axis is generated.

[0163] The aforementioned second polarization unit has a second transmission axis and is configured to transmit light with a polarization direction parallel to the second transmission axis and to reflect light with a polarization direction perpendicular to the second transmission axis.

[0164] The material and type of the second polarization unit are not specifically limited here. For example, the material of the second polarization unit may include PVA (polyvinyl alcohol), PVC (polyvinyl chloride), TAC (cellulose triacetate), etc.; the type of the second polarization unit may include linear polarizers, gratings, etc. Further optionally, the second polarization unit may include TAC, PVA, TAC and PSA (pressure-sensitive adhesive) stacked in sequence.

[0165] The equivalent delay of the third liquid crystal in the third liquid crystal layer is not specifically limited here. For example, the equivalent delay of the third liquid crystal in the third liquid crystal layer can be 321nm, 350nm, 380nm, 400nm, or 441nm, etc.

[0166] It should be noted that the aforementioned display panel may also include multiple liquid crystal units, which are disposed between the first polarization unit and the reflection unit; each liquid crystal unit includes a liquid crystal layer, and the equivalent retardation of the liquid crystal in each liquid crystal layer ranges from 321 to 441 nm. In this case, the equivalent retardation of each liquid crystal in the multiple liquid crystal layers may be the same; or, the equivalent retardation of each liquid crystal in the multiple liquid crystal layers may be different; or, the equivalent retardation of each liquid crystal in the multiple liquid crystal layers may be partially the same, without specific limitations here.

[0167] Figure 2 , Figures 22-23 The second polarization unit 4 in the diagram can be abbreviated as POL2.

[0168] The following is combined Figure 22 and Figure 23 Explain the display principle of the display panel:

[0169] refer to Figure 22As shown, external light rays are directed toward the first transmission axis as follows: Figure 22 The first polarization unit 1 (abbreviated as POL1), as indicated by the arrow, can obtain linearly polarized light with a polarization direction parallel to the first transmission axis; after the linearly polarized light passes through POL1 and is incident on the uncharged liquid crystal LC3, its polarization direction is as follows. Figure 22 Rotating 90° as shown, light with a polarization direction perpendicular to the first transmission axis is obtained. This light with a polarization direction perpendicular to the first transmission axis is directed towards the second polarization unit 4 (abbreviated as POL2) and the reflection unit 2. After being reflected by the reflection unit 2, it passes through the liquid crystal LC3 and POL1 again and enters the human eye without being absorbed by the absorption unit (not shown in the figure). At this time, the display panel is in a bright state.

[0170] refer to Figure 23 As shown, external light rays are directed toward the first transmission axis as follows: Figure 23 POL1, indicated by the arrow, can produce linearly polarized light with a polarization direction parallel to the first transmission axis. After the linearly polarized light passes through POL1 and is incident on the liquid crystal LC3 in the liquid crystal layer under applied voltage, its polarization direction remains unchanged. Figure 23 The direction indicated by the arrow is the direction of light with polarization parallel to the first transmission axis. After the light with polarization parallel to the first transmission axis is incident on POL2 and the reflecting unit (not shown in the figure), the polarization direction is still parallel to the first transmission axis. Finally, it is absorbed by the absorption unit 5, and no light is reflected into the eye. At this time, the display panel is dark.

[0171] It should be noted that... Figure 2 The reflecting unit 2 and the second polarizing unit 4 are integrated together, for example, as an APF. This APF may have a second transmission axis, which allows light with a polarization direction parallel to the second transmission axis to be transmitted, and can also reflect light with a polarization direction perpendicular to the second transmission axis. That is, the APF can both absorb light and polarize it, and this polarization effect is similar to that of the second polarizing unit. In this case, the second polarizing unit can be omitted, so that the reflecting unit can achieve both reflection and polarization functions.

[0172] The following explains in detail how to achieve multiple color displays based on the equivalent delay of the liquid crystal:

[0173] refer to Figures 24-25 As shown, the absorption axis of the first polarization unit is set to 45°, the absorption axis of the second polarization unit is set to -45°, and the liquid crystal LC3 Twist Angle in the liquid crystal layer of the third liquid crystal unit is set to 90° (at this time, the fifth substrate, i.e. Figure 25 The TFT's rubbing direction is 45°, and the sixth substrate, i.e. Figure 25(The CF in this example has a 45° rubbing direction). It should be noted that the CF here refers to a substrate that does not have color filters such as R, G, and B.

[0174] The absorption axis of the first polarization unit is defined as 45°, the absorption axis of the second polarization unit as -45°, and the LC3Twist Angle as 90°. Tests were conducted, and the results are shown in Table 6 below. Figure 26 As shown, when the LC3 equivalent delay changes from 321nm to 381nm, the RLCD displays blue; when the LC3 equivalent delay is 321nm and 331nm, the RLCD displays a higher blue saturation and a better blue display effect; when the LC3 equivalent delay is 341nm and 381nm, the RLCD displays a light blue.

[0175] When the LC3 equivalent delay increases from 381nm to 441nm, the RLCD displays green; when the LC3 equivalent delay increases from 391nm to 411nm, the RLCD displays green, and the green display effect is better at this time; when the LC3 equivalent delay increases from 421nm to 441nm, the saturation of the green displayed by the RLCD gradually decreases and gradually becomes more yellow.

[0176] Table 6

[0177]

[0178] In Table 6 above, Ref. represents the reflectivity of the display panel.

[0179] It should be noted that, according to the equivalent delay Re.=△n×d, the equivalent delay of a liquid crystal is proportional to the cell thickness of the liquid crystal cell. Therefore, the equivalent delay of the liquid crystal can be changed by changing the cell thickness.

[0180] Figures 8-12 , Figures 16-21 , Figures 26-27 These are all color coordinate diagrams, where the horizontal axis is x and the vertical axis is y. This allows us to determine a point on the colorimetric diagram that represents the color of the emitted light.

[0181] In the display panel provided in this application embodiment, the liquid crystal and cell thickness in the liquid crystal unit can be controlled to allow target light of a specific color wavelength to enter the human eye, thereby enabling different color displays.

[0182] Optionally, the third liquid crystal unit further includes a fifth substrate and a sixth substrate, which are disposed opposite to each other. The fifth substrate includes a fifth electrode, and the sixth substrate includes a sixth electrode. The third liquid crystal layer is disposed between the fifth and sixth electrodes. The fifth and sixth electrodes are configured to have a third voltage difference, which ranges from 0 to 6V. Therefore, by controlling the loading voltage of the liquid crystal unit, the equivalent Δn and equivalent Re of the liquid crystal can be affected, thereby enabling the reflective display panel to achieve better color display.

[0183] The structure of the fifth substrate is not specifically limited here. For example, the fifth electrode or the like can be formed directly on the fifth substrate; or, the fifth substrate may include a substrate, and the fifth electrode or the like can be formed directly on the substrate. The specific application shall prevail.

[0184] The structure of the sixth substrate is not specifically limited here. For example, the sixth electrode or the like can be formed directly on the fifth substrate; or, the sixth substrate may include a substrate, and the sixth electrode or the like can be formed directly on the substrate. The specific application shall prevail.

[0185] The third voltage difference mentioned above is not specifically limited here. For example, the third voltage difference can be 0V, 2V, 4V, 5V or 6V, etc.

[0186] Optionally, the transmission axis of the second polarization unit is not parallel to the transmission axis of the first polarization unit.

[0187] Here, there is no specific limitation on the transmission axis of the second polarization unit and the transmission axis of the first polarization unit. For example, the angle between the transmission axis of the second polarization unit and the transmission axis of the first polarization unit can be 45°, 90° or 135°, etc.

[0188] In the display panel provided in this application embodiment, the first polarization unit has a first transmission axis and can generate polarized light with a polarization direction parallel to the first transmission axis. Thus, by changing the angle between the transmission axis of the first polarization unit and the transmission axis of the second polarization unit, the transmission of light in a specific direction can be controlled. Combined with the liquid crystal unit, the reflective display panel can then achieve different color displays.

[0189] Optionally, the transmission axis of the second polarization unit is perpendicular to the transmission axis of the first polarization unit.

[0190] The following explains in detail how to achieve multiple color displays based on the angle between the transmission axis of the second polarization unit and the transmission axis of the first polarization unit:

[0191] refer to Figures 24-25As shown, the absorption axis of the first polarization unit is set to 45°, the absorption axis of the second polarization unit is set to -45°, and the liquid crystal LC3 Twist Angle in the liquid crystal layer of the third liquid crystal unit is set to 90° (at this time, the Rubbing direction of the fifth substrate is 45°; the Rubbing direction of the sixth substrate is 45°).

[0192] The absorption axis of the first polarization unit is defined as 45°, the absorption axis of the second polarization unit as -45°, the LC3 Twist Angle as 90°, and the LC3 equivalent retardation as 356 nm. Tests were conducted, and the results are shown in Table 7 below. Figure 27 As shown, when the absorption axis of the second polarization unit is controlled at -45°, and the absorption axis angle of the first polarization unit is changed from 0° to 25°, the RLCD gradually displays yellow; when the absorption axis of the first polarization unit is 0° and 5°, the RLCD displays light yellow; when the absorption axis of the first polarization unit is 10°, 15° and 20°, the yellow saturation of the RLCD is higher and the display effect is better.

[0193] When the absorption axis of the first polarization unit is changed from 25° to 75°, the RLCD gradually displays blue-green; when the absorption axis of the first polarization unit is 25° and 30°, the RLCD displays yellow-green; when the absorption axis of the first polarization unit is 35° and 40°, the RLCD displays light green, at which point the green display effect is optimal; when the absorption axis of the first polarization unit is 45° and 50°, the RLCD displays light blue; when the absorption axis of the first polarization unit changes from 55° to 75°, the blue saturation displayed by the RLCD gradually increases.

[0194] When the absorption axis of the first polarization unit is changed from 80° to 90°, the RLCD gradually displays yellow-orange; when the absorption axis of the first polarization unit is 80°, the RLCD displays the highest yellow saturation; when the absorption axis of the first polarization unit is 85° and 90°, the RLCD displays orange.

[0195] Table 7

[0196]

[0197] Optionally, refer to Figure 2As shown, the display panel also includes an absorption unit 5, which is configured to absorb light parallel to the transmission axis of the second polarization unit 4. When the second polarization unit 4 is located on the side of the reflective unit closer to the third liquid crystal unit 33, the absorption unit 5 is located on the side of the reflective unit farther from the second polarization unit 4; conversely, when the second polarization unit 4 is located on the side of the reflective unit farther from the third liquid crystal unit 33, the absorption unit 5 is located on the side of the second polarization unit 4 farther from the reflective unit. This allows light to be absorbed through the absorption unit, ensuring high contrast in the reflective display panel.

[0198] Optionally, the absorption unit includes black ink or a third polarization unit, the transmission axis of which is perpendicular to the transmission axis of the second polarization unit. This makes it easier to form the absorption unit and simplifies its implementation.

[0199] The aforementioned third polarization unit may have a third transmission axis, which is configured to absorb polarized light parallel to the second transmission axis.

[0200] Embodiments of this application also provide a display device, including the display panel described above.

[0201] The aforementioned display device can be a rigid display device (i.e., a screen that cannot be bent), and this is not limited. The aforementioned display device can be an LCD display device, and more specifically, a reflective LCD display device. The aforementioned display device can be any product or component with a display function, such as a television, digital camera, mobile phone, or tablet computer; the aforementioned display device can also be applied in fields such as identity recognition and medical devices, with products that have been promoted or have good promotion prospects including security identity authentication, smart door locks, and medical image acquisition. This display device has advantages such as high reflectivity, ability to display multiple colors, low cost, fast response time, high environmental reliability, good display effect, long lifespan, high stability, high contrast, good imaging quality, and high product quality.

[0202] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of this application may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0203] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A display panel, wherein, include: First polarization unit; A reflection unit is disposed opposite to the first polarization unit; At least one liquid crystal cell is disposed between the first polarization cell and the reflection cell; the liquid crystal cell includes a liquid crystal layer, the liquid crystal in the liquid crystal layer has birefringence and optical rotation, and the total equivalent delay of the liquid crystal in all the liquid crystal cells ranges from 100 to 441 nm; The display panel includes at least a first liquid crystal unit and a second liquid crystal unit, wherein the first liquid crystal unit is disposed between the first polarization unit and the second liquid crystal unit, and the second liquid crystal unit is disposed between the first liquid crystal unit and the reflection unit; The first liquid crystal unit includes a first liquid crystal layer, and the second liquid crystal unit includes a second liquid crystal layer. The equivalent delay of the first liquid crystal in the first liquid crystal layer is greater than the equivalent delay of the second liquid crystal in the second liquid crystal layer. The display panel includes the first liquid crystal unit and the second liquid crystal unit, and the equivalent delay of the first liquid crystal in the first liquid crystal layer ranges from 200 to 400 nm. The equivalent delay of the second liquid crystal in the second liquid crystal layer ranges from 100 to 200 nm.

2. The display panel according to claim 1, wherein, The torsion angle range of the liquid crystal in the liquid crystal layer of each liquid crystal cell includes 0-90°.

3. The display panel according to claim 2, wherein, The liquid crystal in the liquid crystal layer of each liquid crystal unit is a cholesteric liquid crystal; Each of the liquid crystal units further includes two oppositely disposed electrodes, with the cholesteric liquid crystal located between the two oppositely disposed electrodes.

4. The display panel according to claim 1, wherein, The equivalent optical axis direction of the first liquid crystal in the first liquid crystal layer is the same as that of the second liquid crystal in the second liquid crystal layer, and the angle between the first liquid crystal and the transmission axis of the first polarization unit is in the range of 42-48°.

5. The display panel according to claim 4, wherein, The first liquid crystal in the first liquid crystal layer has a first twist angle, and the second liquid crystal in the second liquid crystal layer has a second twist angle. One of the first twist angle and the second twist angle has a twist angle range of 0-34°, and the other twist angle has a twist angle range of 89-90°.

6. The display panel according to claim 5, wherein, The thickness of the first liquid crystal cell along the direction perpendicular to the first polarization cell is greater than the thickness of the second liquid crystal cell along the direction perpendicular to the first polarization cell.

7. The display panel according to claim 6, wherein, The first liquid crystal unit further includes a first substrate and a second substrate, the first substrate and the second substrate being disposed opposite to each other, the first substrate including a first electrode, the second substrate including a second electrode, and the first liquid crystal layer being disposed between the first electrode and the second electrode; the second liquid crystal unit further includes a third substrate and a fourth substrate, the third substrate and the fourth substrate being disposed opposite to each other, the third substrate including a third electrode, the fourth substrate including a fourth electrode, and the second liquid crystal layer being disposed between the third electrode and the fourth electrode; The first electrode and the second electrode are configured to have a first voltage difference, and the third electrode and the fourth electrode are configured to have a second voltage difference. When either the first voltage difference or the second voltage difference is not zero, the total equivalent delay of the first liquid crystal in the first liquid crystal layer and the second liquid crystal in the second liquid crystal layer is less than the total equivalent delay of the first liquid crystal in the first liquid crystal layer and the second liquid crystal in the second liquid crystal layer when both the first voltage difference and the second voltage difference are zero.

8. The display panel according to claim 7, wherein, When the first voltage difference is configured to be at a first fixed value and the second voltage difference is configured to vary within a first preset range, the equivalent delay of the first liquid crystal in the first liquid crystal layer ranges from 200 to 400 nm; and the equivalent delay of the second liquid crystal in the second liquid crystal layer ranges from 130 to 154 nm.

9. The display panel according to claim 8, wherein, The first fixed value range includes 0-6V; the first preset range includes 0-10V.

10. The display panel according to claim 7, wherein, When the second voltage difference is configured to be at a second fixed value and the first voltage difference is configured to vary within a second preset range, the equivalent delay of the first liquid crystal in the first liquid crystal layer ranges from 240 to 275 nm; and the equivalent delay of the second liquid crystal in the second liquid crystal layer ranges from 100 to 200 nm.

11. The display panel according to claim 10, wherein, The second fixed value range includes 0-10V; the second preset range includes 0-10V.

12. A display device, wherein, Includes the display panel as described in any one of claims 1-11.

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