Display module and display device

Abstract

The present disclosure belongs to the field of display, and discloses a display module and a display device. The display module comprises a display panel, and a light modulation layer is arranged on the light exit side of the display panel. The light modulation layer comprises a polarization modulation layer and a direction modulation layer arranged in a stack. The polarization modulation layer is arranged between the display panel and the direction modulation layer. The polarization modulation layer is used for adjusting the polarization state of the light emitted by the display panel, and the direction modulation layer is used for adjusting the direction of the light emitted by the polarization modulation layer. At least one of the polarization modulation layer and the direction modulation layer is an electrically controlled modulation layer, which is used for switching between at least two different states to switch the exit viewing angle of the light emitted by the display panel. The display module can switch between the front viewing angle and the side viewing angle, has high diffraction efficiency, small energy loss, and can improve the light brightness and the picture contrast of the display panel, thereby improving the display quality.

Description

Technical Field

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

[0002] The viewing angle requirements for display devices vary depending on the usage scenario. For example, for mobile terminals such as smartphones, users want the displayed content to be seen only by the user directly facing the screen to prevent sensitive information from being seen by others; for in-vehicle display devices, the driver and passenger want the displayed content to face their respective sides.

[0003] Currently, display panels use a polymer dispersed liquid crystal (PDLC) layer on the light-emitting side, and viewing angle switching is achieved by electronically controlling the PDLC layer to switch between a transparent state and a scattering state. In the scattering state, light is scattered at large angles, creating a wide viewing angle; in the transparent state, light is emitted along the normal direction, creating a narrow viewing angle. However, this solution relies on the scattering effect. Light is scattered multiple times as it passes through the PDLC layer, and some light energy deviates from the target emission direction, resulting in low light energy utilization. This affects the clarity and contrast of the displayed image, failing to meet the requirements for high-quality display and unable to achieve a specific viewing angle, thus failing to meet the diverse viewing angle needs of users. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide a display module and a display device.

[0005] Firstly, a display module is provided, comprising: Display panel; A dimming layer is disposed on the light-emitting side of the display panel. The dimming layer includes a polarization modulation layer and a direction modulation layer stacked together. The polarization modulation layer is disposed between the display panel and the direction modulation layer. The polarization modulation layer is used at least to adjust the polarization state of the light emitted from the display panel, and the direction modulation layer is used at least to adjust the direction of the light emitted from the polarization modulation layer. At least one of the polarization modulation layer and the orientation modulation layer is an electrically controlled modulation layer, which is used to switch between at least two different states to switch the emission angle of the light emitted from the display panel.

[0006] In addition, the display module of the present invention may also have the following additional technical features: In some embodiments, the directional modulation layer is an electrically controlled modulation layer, which has at least a first phase state and a second phase state; In the first phase state, the direction modulation layer does not generate geometric phase modulation, so that the light emitted from the display panel is emitted along the positive viewing angle direction; In the second phase state, the direction modulation layer generates geometric phase modulation to deflect the light emitted from the display panel to a preset direction, which includes a left viewing angle and / or a right viewing angle.

[0007] In some embodiments, the phase delay of the directional modulation layer is 0 in the first phase state and half a wavelength in the second phase state.

[0008] In some embodiments, the orientation modulation layer is a geometric phase grating, which includes a first liquid crystal layer and at least one first alignment layer. The first alignment layer includes a plurality of trenches, the extension directions of which are arranged in a periodic gradient in a plane parallel to the display panel. The extension directions of each trench in the same period are continuously rotated within the range of 0 to 180°, so that the long axis direction of a plurality of liquid crystal molecules in the first liquid crystal layer is consistent with the extension direction of the trenches. The directional modulation layer is used to apply different driving voltages to the first liquid crystal layer so that the geometric phase grating has at least two different phase delays.

[0009] In some embodiments, the orientation modulation layer further includes a first substrate and a second substrate disposed opposite to each other, the first liquid crystal layer being disposed between the first substrate and the second substrate; a first electrode being disposed between the first liquid crystal layer and the first substrate, and a second electrode being disposed between the first liquid crystal layer and the second substrate; the first electrode and the second electrode are used to apply different driving voltages to the first liquid crystal layer.

[0010] In some embodiments, the display panel includes multiple pixel regions, each pixel region including multiple sub-pixels of the same color, and the geometric phase grating includes multiple grating regions, the grating regions being configured in a one-to-one correspondence with the pixel regions, and the grating periods of the grating regions corresponding to pixel regions of different colors being different.

[0011] In some embodiments, the trenches in the first alignment layer have an arrangement period of 1 μm to 20 μm, a depth of 80 nm to 200 nm, and a duty cycle of (0.2~5):1.

[0012] In some embodiments, the orientation modulation layer is a geometric phase metasurface structure, which includes a plurality of anisotropic structural units. The plurality of anisotropic structural units are arranged in a periodic gradient in a plane parallel to the display panel, and the major axis direction of the anisotropic structural units in the same period is continuously rotated and arranged in the range of 0 to 180°. The geometric phase metasurface structure has a fixed phase delay.

[0013] In some embodiments, the anisotropic structural unit is a liquid crystal molecule or a nanopillar.

[0014] In some embodiments, the polarization modulation layer is an electrically controlled modulation layer, and the polarization modulation layer has at least a first state and a second state; In the first state, the polarization modulation layer maintains the polarization state of the light emitted from the display panel; In the second state, the polarization modulation layer changes the polarization state of the light emitted from the display panel.

[0015] In some embodiments, in the first state, the phase delay of the polarization modulation layer is 0 or one wavelength; In the second state, the phase delay of the polarization modulation layer is one-quarter wavelength or three-quarter wavelength.

[0016] In some embodiments, the polarization modulation layer includes a second liquid crystal layer and a second alignment layer. The second alignment layer includes a plurality of trenches, and the extension direction of the plurality of trenches is consistent in a plane parallel to the display panel, so that the long axis direction of a plurality of liquid crystal molecules in the second liquid crystal layer is consistent. The polarization modulation layer is used to apply different driving voltages to the second liquid crystal layer so that the polarization modulation layer has at least two different phase delays.

[0017] In some embodiments, the polarization modulation layer is a liquid crystal polymer film, the liquid crystal polymer film includes a third liquid crystal layer, the third liquid crystal layer includes a plurality of liquid crystal molecules, the long axis of the plurality of liquid crystal molecules are aligned, and the liquid crystal polymer film has a fixed phase retardation.

[0018] A second aspect of the present invention provides a display device, the display device comprising the display module described in any embodiment of the present application.

[0019] The display module and display device disclosed herein utilize a polarization modulation layer and a direction modulation layer disposed on the light-emitting side of the display panel. By adjusting the state of the polarization modulation layer and / or the direction modulation layer, the display panel can switch between a frontal viewing angle and a side viewing angle (including a left viewing angle and a right viewing angle). The light is deflected in a diffraction manner through the synergistic effect of polarization modulation and geometric phase modulation, with a diffraction efficiency of not less than 90%. This avoids the light energy loss caused by scattering in traditional viewing angle switching schemes, reduces the energy loss of light during transmission, thereby improving the light output brightness and image contrast of the display panel and improving display quality. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in this disclosure, the accompanying drawings used in some embodiments of this disclosure will be briefly described below. Obviously, the drawings described below are only drawings of some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams and are not intended to limit the actual size of the product, the actual flow of the method, the actual timing of the signals, etc. involved in the embodiments of this disclosure.

[0021] Figure 1 This is a schematic diagram of the structure of an existing display module; Figure 2 This is a schematic diagram illustrating the working principle of an existing display module without applied voltage to the PDLC layer. Figure 3 Schematic diagram of the working principle of applying voltage to the PDLC layer in an existing display module; Figure 4 This is a schematic diagram of the structure of the display module provided in the embodiments of this application; Figure 5 This is a schematic diagram of the trench arrangement in the first alignment layer provided in an embodiment of this application; Figure 6 A schematic diagram of the arrangement of liquid crystal molecules in the first liquid crystal layer provided in an embodiment of this application; Figure 7 and Figure 8 Electron microscope image of liquid crystal molecules in the first liquid crystal layer provided for embodiments of this application; Figure 9 This is a first combined structure diagram of the polarization modulation pattern and the direction modulation pattern provided in the embodiments of this application; Figure 10 A single-layer alignment structure diagram of the directional modulation layer provided in the embodiments of this application; Figure 11 This is a schematic diagram of the deflection of circularly polarized light after passing through a geometric phase grating, provided in an embodiment of this application. Figure 12 A structural diagram showing the corresponding pixel arrangement and geometric phase grating provided in the embodiments of this application; Figure 13 This is a second combined structure diagram of the polarization modulation pattern and the direction modulation pattern provided in the embodiments of this application; Figure 14 This is a second combined structure diagram of polarization modulation pattern and direction modulation pattern provided in the embodiments of this application.

[0022] In the above image: 10 Display modules; 11 Display panel; 111 Red subpixel; 112 Green subpixel; 113 Blue subpixel; 12 Polarization modulation layer; 121 First liquid crystal layer; 122 First substrate; 123 Second substrate; 124 First electrode; 125 Second electrode; 126 First alignment layer; 1261 Trench; 13. Orientation modulation layer; 131. Second liquid crystal layer; 132. Third substrate; 133. Fourth substrate; 134. Third electrode; 135. Fourth electrode; 136. Second alignment layer; 14 Collimating prism; 15 Backlight module; 16 PDLC layer. Detailed Implementation

[0023] The technical solutions in some embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments provided in this disclosure are within the scope of protection of this disclosure.

[0024] Unless the context otherwise requires, throughout the specification and claims, the term "comprise" and its other forms, such as the third-person singular "comprises" and the present participle "comprising," are 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 embodiments," "example," "specific example," or "some examples," etc., 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 disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be included in any suitable manner in any one or more embodiments or examples.

[0025] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this disclosure, unless otherwise stated, "a plurality of" means two or more.

[0026] "At least one of A, B and C" has the same meaning as "at least one of A, B or C", both including the following combinations of A, B and C: only A, only B, only C, combinations of A and B, combinations of A and C, combinations of B and C, and combinations of A, B and C.

[0027] "A and / or B" includes the following three combinations: A only, B only, and a combination of A and B.

[0028] It should be understood that when a layer or element is referred to as being on another layer or substrate, it can mean that the layer or element is directly on the other layer or substrate, or that there is an intermediate layer between the layer or element and the other layer or substrate.

[0029] Exemplary embodiments are described herein with reference to sectional views and / or plan views, which are idealized exemplary drawings. In the drawings, the thickness of layers and regions is enlarged for clarity. Therefore, variations in shape relative to the drawings are contemplated due to, for example, manufacturing techniques and / or tolerances. Thus, exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but rather include shape deviations due to, for example, manufacturing processes.

[0030] In the information age, protecting screen privacy has become a growing consumer demand. With advancements in display technology, wide-viewing-angle technologies such as Adaptive Digital Sublimation (ADS) have gradually become mainstream, but their wide viewing angles also bring the risk of privacy leaks. To address this contradiction, passive privacy screen protectors have emerged. These protectors typically employ a micro-visor optical structure, attaching a film with tiny vertical blades to the screen surface to restrict the direction of light emission, achieving blurred content from side views. This solution has significant drawbacks: applying a privacy screen protector sacrifices screen brightness (typically decreasing by 30%), produces optical distortions such as rainbow patterns, and results in a poor user experience.

[0031] Another privacy protection technology solution is, such as Figure 1 As shown, a polymer-dispersed liquid crystal layer (PDLC layer 16) and a collimating prism 14 are sequentially disposed on the backlight side of the display panel 11. The PDLC layer 16 is prepared by curing two electrode layers and a polymer monomer / liquid crystal mixture disposed between the two electrode layers to form a polymer / liquid crystal composite material. Figure 2 As shown, without electricity, the director of the liquid crystal molecules is randomly distributed under the influence of the polymer network, and the film exhibits strong light scattering; Figure 3 As shown, when electricity is applied, the long axis of the liquid crystal molecules is parallel to the electric field, and the thin film is transparent.

[0032] When the PDLC layer 16 is powered on, it is in a transparent state. The light collimated by the collimating prism 14 can enter the display panel 11 directly. After being modulated by the liquid crystal molecules of the display panel 11, a narrow viewing angle in a privacy-protected state is formed. When the PDLC layer 16 is not powered on, it is in a scattering state. When the light collimated by the collimating prism 14 passes through the PDLC layer 16, it is scattered, forming scattered light in various directions. After being modulated by the liquid crystal molecules of the display panel 11, a wide viewing angle in a shared state is formed.

[0033] The existing PDLC layer 16 itself will cause optical loss, which will reduce the brightness and contrast of the display panel 11 and cannot meet the requirements of high-quality display; and although it can achieve the switching of wide and narrow viewing angles, it cannot achieve specific viewing angles and cannot meet the diverse viewing needs of users.

[0034] To solve the above-mentioned technical problems, the first aspect of the embodiments of this application is as follows: Figure 4 As shown, a display module 10 is provided, including: Display panel 11; A dimming layer is disposed on the light-emitting side of the display panel 11. The dimming layer includes a polarization modulation layer 12 and a direction modulation layer 13 stacked together. The polarization modulation layer 12 is disposed between the display panel 11 and the direction modulation layer 13. The polarization modulation layer 12 is used at least to adjust the polarization state of the light emitted from the display panel 11, and the direction modulation layer 13 is used at least to adjust the direction of the light emitted from the polarization modulation layer 12. At least one of the polarization modulation layer 12 and the orientation modulation layer 13 is an electrically controlled modulation layer, which is used to switch between at least two different states to switch the emission angle of the light emitted from the display panel 11.

[0035] Specifically, a polarization modulation layer 12 and a direction modulation layer 13 are stacked sequentially on the light-emitting side of the display panel 11. The polarization modulation layer 12 is used to adjust the polarization state of the light emitted from the display panel 11, and the direction modulation layer 13 is used to adjust the direction of the light emitted from the polarization modulation layer 12.

[0036] Among them, at least one of the polarization modulation layer 12 and the direction modulation layer 13 is an electrically controlled modulation layer. The electrically controlled modulation layer switches between at least two different optical states by controlling whether a voltage is applied and the magnitude of the applied voltage.

[0037] For example, polarization modulation layer 12 is an electrically controlled modulation layer that switches between at least two different states, and directional modulation layer 13 has a fixed phase modulation state. Alternatively, polarization modulation layer 12 has a fixed phase modulation state, and directional modulation layer 13 is an electrically controlled modulation layer that switches between at least two different states. Or, both polarization modulation layer 12 and directional modulation layer 13 are electrically controlled modulation layers, such that both polarization modulation layer 12 and directional modulation layer 13 can switch between at least two different states.

[0038] In this embodiment, by utilizing the polarization modulation layer 12 and the orientation modulation layer 13 disposed on the light-emitting side of the display panel 11, the state of the polarization modulation layer 12 and / or the orientation modulation layer 13 can be adjusted to enable the display panel 11 to switch between a frontal viewing angle (anti-peeping) and a side viewing angle (including left and right viewing angles). The light is deflected in a diffraction manner through the synergistic effect of polarization modulation and geometric phase modulation, with a diffraction efficiency of not less than 90%. This avoids the light energy loss caused by scattering in traditional viewing angle switching schemes, reduces the energy loss of light during transmission, thereby improving the light output brightness and image contrast of the display panel 11 and improving display quality.

[0039] In some embodiments, the directional modulation layer 13 is an electrically controlled modulation layer, which has at least a first phase state and a second phase state; In the first phase state, the directional modulation layer 13 does not generate geometric phase modulation so that the light emitted from the display panel 11 is emitted along the positive viewing angle direction; In the second phase state, the direction modulation layer 13 generates geometric phase modulation to deflect the light emitted from the display panel 11 to a preset direction, which includes a left viewing angle and / or a right viewing angle.

[0040] Specifically, the directional modulation layer 13 has at least a first phase state and a second phase state. For example, the directional modulation layer 13 has a first phase state when a voltage is applied and a second phase state when no voltage is applied. In the first phase state, the directional modulation layer 13 does not generate geometric phase modulation, and the light emitted from the display panel 11 is emitted along the positive viewing angle direction. In the second phase state, the directional modulation layer 13 generates geometric phase modulation, which can realize the conversion between left-handed and right-handed circularly polarized light. It can also deflect the light emitted from the display panel 11 to a preset direction by utilizing the multiple liquid crystal molecules in the directional modulation layer 13 that are arranged in a periodic and gradually changing manner. The preset direction includes the left viewing angle or the right viewing angle, or both. With the emission line of the display panel 11 as a reference, the left viewing angle is within a preset angle range to the left of the normal, and the right viewing angle is within a preset angle range to the left of the normal. For example, the angle between the viewing angle and the normal of the display panel 11 is 30°~60°, and the angle between the right viewing angle and the normal of the display panel 11 is 30°~60°. For example, 45° to the left of the normal is the left viewing angle, and 45° to the right of the normal is the right viewing angle.

[0041] In some embodiments, in the first phase state, the phase delay of the directional modulation layer 13 is 0; in the second phase state, the phase delay of the directional modulation layer 13 is half a wavelength.

[0042] Specifically, in the first phase state, the phase delay of the directional modulation layer 13 is 0, no geometric phase modulation is generated, the light is not deflected, and the emitted light from the display panel 11 is emitted along the positive viewing angle direction. In the second phase state, the phase delay is half a wavelength (λ / 2), generating geometric phase modulation, which enables the conversion between left-handed and right-handed circularly polarized light, and utilizes multiple liquid crystal molecules arranged in a periodic gradient to deflect the emitted light from the display panel 11 to a preset direction.

[0043] In this example, by switching the directional modulation layer 13 between a first phase state and a second phase state, the direction of the emitted light from the display panel 11 can be precisely controlled, thereby achieving viewing angle switching.

[0044] In some implementations, such as Figures 5 to 9 As shown, the orientation modulation layer 13 is a geometric phase grating, which includes a first liquid crystal layer 121 and at least one first alignment layer 126. The first alignment layer 126 includes a plurality of trenches 1261. The extension directions of the plurality of trenches 1261 are arranged in a periodic gradient in a plane parallel to the display panel 11, and the extension directions of each trench 1261 in the same period are continuously rotated and arranged in the range of 0 to 180°, so that the long axis direction of the plurality of liquid crystal molecules in the first liquid crystal layer 121 is consistent with the extension direction of the trenches 1261. The directional modulation layer 13 is used to apply different driving voltages to the first liquid crystal layer 121 so that the geometric phase grating has at least two different phase delays.

[0045] Specifically, the direction modulation layer 13 can be an adjustable geometric phase (Pancharatnam–Berry, PB) grating. The PB grating controls the optical wavefront phase by rotating scattering elements with the same geometric structure within an azimuth angle range of 0–180° (the phase change is 0 to 2nπ), altering the wavefront of the transmitted or reflected wave. The PB grating can deflect circularly polarized light after passing through it, directing it towards ±1st order diffraction, such as... Figure 11 As shown, left-handed circularly polarized light is deflected to the -1st order diffraction after passing through a PB grating and converted into right-handed circularly polarized light; right-handed circularly polarized light is deflected to the +1st order diffraction after passing through a PB grating and converted into left-handed circularly polarized light.

[0046] The PB grating includes a first liquid crystal layer 121 and a first alignment layer 126. The first liquid crystal layer 121 includes a plurality of liquid crystal molecules, which are rod-shaped and made of birefringent material. The first alignment layer 126 is made of polymer material (such as polyimide PI), inorganic material (such as SiOX, SinX), nanoimprint stencil (such as resin), or organic material (such as silicone rubber (PMDS), photoresist, etc.), preferably a nanoimprint stencil. The first alignment layer 126 is used to provide an anisotropic surface to guide the alignment of liquid crystal molecules.

[0047] like Figures 6 to 8 As shown, the orientation vectors (such as the long axis direction) of multiple liquid crystal molecules within the first liquid crystal layer 121 are determined by the extension directions of multiple trenches 1261 within the first alignment layer 126, and both are arranged in a periodic, gradually changing pattern. Figure 5 As shown, multiple grooves 1261 are arranged in a periodic gradient or periodic rotational arrangement in a plane parallel to the display panel 11. That is, within the same grating period, the extension direction of multiple grooves 1261 is continuously rotated and arranged from 0 to 180°. The distance traversed by the extension direction of the grooves 1261 rotating by 180° is the grating period T. Multiple liquid crystal molecules in the first liquid crystal layer 121 will be arranged along the extension direction of the grooves 1261, so that the director of multiple liquid crystal molecules is also arranged in a periodic gradient, generating a spatially changing geometric phase on the incident circularly polarized light to achieve the deflection of the beam direction.

[0048] Within the first alignment layer 126, the grating period (i.e., alignment period) of the trenches 1261 ranges from 1 μm to 20 μm, the depth of the trenches 1261 ranges from 80 nm to 200 nm, and the duty cycle is (0.2~5):1. The depth and width of the trenches 1261 together determine the anchoring strength of the first alignment layer 126 for the liquid crystal molecules. When the depth is less than 80 nm, the anchoring force is insufficient, and the alignment consistency of the liquid crystal molecules decreases; when the depth is greater than 200 nm, nanoimprinting demolding becomes difficult, and the structure is easily damaged. The duty cycle within this range can be adjusted according to actual process conditions to achieve the best alignment effect and process yield. For example, the grating period can be 1μm, 5μm, 10μm, 15μm, 20μm, etc., and the trench 1261 depth can be 80nm, 120nm, 150nm, 180nm, 200nm, etc.; the duty cycle can be 50nm:50nm, 100nm:100nm, 150nm:150nm, or other sizes can be set according to actual needs.

[0049] Dividing a grating period into m steps results in a rotation angle a = 180 / m. The number of steps m can be set according to actual needs; the more steps, the higher the diffraction efficiency. However, increasing m increases the manufacturing difficulty and process cost of the nanoimprint template. For example, the number of steps m can be 2~12, such as 2, 5, 7, 8, 10, 12, etc. Taking a step number of 12 as an example, the rotation angle is 15°. That is, within one grating period, the long axis direction of the liquid crystal molecules or the extension direction of the groove 1261 rotates continuously and is discrete into m steps. The long axis direction of the liquid crystal molecules in each step is consistent, and the angle between the long axis directions of the liquid crystal molecules between adjacent steps is 15°, forming 12 different orientation domains in each period.

[0050] The first alignment layer 126 can be prepared using interferometric exposure technology, adjustable programmable exposure technology or nanoimprint technology to achieve continuous orientation of the extension direction of multiple trenches 1261 in the range of 0~180°. Nanoimprint technology is preferred for preparation, as it is suitable for mass production and low cost replication of micro and nano structures.

[0051] The nanoimprinting technology is as follows: 1) Preparation of nanoimprint template: According to the preset periodic rotation distribution pattern, an electron beam direct writing pattern is prepared; an initial template structure is formed on the substrate by electron beam direct writing exposure, and the initial template structure has a groove 1261 pattern corresponding to the preset distribution; using the initial template structure as a master, the nanoimprint template is repeatedly printed through the nanoimprint template preparation process to form a nanoimprint template; 2) Imprinting, curing and demolding: The substrate coated with imprinting adhesive is imprinted, cured and demolded using the nanoimprint template, and the groove 1261 pattern is transferred to the imprinting adhesive layer to form the first alignment layer 126; 3) Liquid crystal injection: Liquid crystal is injected into the groove 1261 of the first alignment layer 126, and the liquid crystal molecules are arranged along the groove 1261 to achieve a periodic rotation arrangement of 0~180°.

[0052] The orientation modulation layer 13 is used to apply different driving voltages to the first liquid crystal layer 121, so that the geometric phase grating has at least two different phase retardation amounts. When a voltage is applied to the orientation modulation layer 13, the orientation modulation layer 13 has a first phase retardation amount of 0, all liquid crystal molecules are aligned perpendicular to the first substrate 122 along their long axis, effective birefringence disappears, geometric phase modulation is suppressed, and light passes directly through the orientation modulation layer 13 along its original direction, with the display panel 11 emitting light at a positive viewing angle. When no voltage is applied, the orientation modulation layer 13 has a second phase retardation amount of half a wavelength, the liquid crystal molecules are in an initial orientation state, and the long axis of the liquid crystal molecules is arranged in a periodically gradually changing pattern in the plane. Circularly polarized light emitted from the polarization modulation layer 12 enters the orientation modulation layer 13, and the circularly polarized light has a spatially varying geometric phase, resulting in deflection and emitting light at a side viewing angle. Thus, the switching between the positive and side viewing angles is achieved to meet the viewing angle requirements of users in different usage scenarios.

[0053] In some implementations, such as Figure 9 As shown, the directional modulation layer 13 further includes a first substrate 122 and a second substrate 123 disposed opposite to each other, and a first liquid crystal layer 121 disposed between the first substrate 122 and the second substrate 123; a first electrode 124 is disposed between the first liquid crystal layer 121 and the first substrate 122, and a second electrode 125 is disposed between the first liquid crystal layer 121 and the second substrate 123; the first electrode 124 and the second electrode 125 are used to apply different driving voltages to the first liquid crystal layer 121.

[0054] Specifically, different driving voltages are applied to the first liquid crystal layer 121 using the first electrode 124 and the second electrode to achieve switching of the orientation modulation layer 13 between the first phase state and the second phase state. The first alignment layer 126 within the orientation modulation layer 13 can be one or two layers, such as the first alignment layer 126 being disposed between the first electrode 124 and the first liquid crystal layer 121, and / or, the first alignment layer 126 being disposed between the second electrode 125 and the first liquid crystal layer 121 (e.g.,...). Figure 10 (As shown). Preferably, two first alignment layers 126 are used, such as... Figure 9 As shown, the trenches 1261 in the two first alignment layers 126 are symmetrically arranged on both sides of the first liquid crystal layer 121, and the arrangement of the trenches 1261 is consistent. The materials of the first substrate 122 and the second substrate 123 can be the same or different. They can be flexible substrates (such as polyethylene terephthalate or cellulose triacetate film) or rigid substrates (such as glass). Flexible substrates can be polyethylene terephthalate (PET) or cellulose triacetate film (TAC), etc., and rigid substrates can be glass, etc.

[0055] When a voltage is applied to the directional modulation layer 13, the phase retardation is 0; when no voltage is applied, the phase retardation is λ / 2, and the pretilt angle of the liquid crystal molecules is 0°, that is, the long axis of the liquid crystal molecules is parallel to the plane of the first substrate 122. The 0° pretilt angle enables the rotational arrangement of the liquid crystal molecules in the plane to produce pure geometric phase modulation of the incident light, avoiding the introduction of additional vertical phase retardation components due to molecular tilting.

[0056] In some implementations, such as Figure 12 As shown, the display panel 11 includes multiple pixel areas, each pixel area includes multiple sub-pixels of the same color, the geometric phase grating includes multiple grating areas, the grating areas are set in one-to-one correspondence with the pixel areas, and the grating period of the grating areas corresponding to pixel areas of different colors is different.

[0057] Specifically, different colored pixel regions correspond to different grating periods. Each grating period is determined by the wavelength of the light emitted from its corresponding sub-pixel. For example, the grating period T corresponds to the red sub-pixel 111. R The grating period T corresponding to green sub-pixel 112 G The raster period T corresponding to the blue sub-pixel 113 B Then T R >T G >T B This ensures that light of different wavelengths exits at the same deflection angle after passing through their respective grating areas, guaranteeing the consistency of different colors of light during the switching of viewing angles.

[0058] For example, if the display panel 11 adopts a strip-shaped pixel arrangement structure, that is, in each pixel unit, the red sub-pixel 111, the green sub-pixel 112, and the blue sub-pixel 113 are arranged sequentially along a predetermined direction; the geometric phase grating includes multiple grating regions, and the grating regions are configured one-to-one with the sub-pixels; wherein, the grating region corresponding to the red sub-pixel 111 has a first grating period, the grating region corresponding to the green sub-pixel 112 has a second grating period, and the grating region corresponding to the blue sub-pixel 113 has a third grating period, and the first grating period, the second grating period, and the third grating period are different from each other to achieve maximum light diffraction efficiency. Optionally, the pixel arrangement structure of the display panel 11 is not limited to a strip-shaped arrangement, and the grating regions can also be adapted to other pixel arrangement methods.

[0059] In some implementations, such as Figure 13 As shown, the directional modulation layer 13 is a geometric phase metasurface structure, which includes multiple anisotropic structural units. The multiple anisotropic structural units are arranged in a periodic gradient in a plane parallel to the display panel 11, and the major axis direction of the anisotropic structural units in the same period is continuously rotated and arranged in the range of 0~180°. The geometric phase metasurface structure has a fixed phase delay.

[0060] Specifically, the directional modulation layer 13 can adopt a fixed geometric phase metasurface structure. The geometric phase metasurface structure has a fixed phase delay of half a wavelength (λ / 2) and does not require voltage adjustment. Etching a subwavelength grating structure on a uniform dielectric surface constitutes a metasurface structure. The geometric phase metasurface structure includes multiple anisotropic structural units, which are arranged in a periodic gradient in a plane parallel to the display panel 11. Within the same period, the major axis direction of the anisotropic structural units rotates continuously within the range of 0 to 180°.

[0061] Furthermore, the anisotropic structural unit is a liquid crystal molecule or a nanopillar. The nanopillar is made of titanium dioxide (TiO2) or silicon (Si), and has an elliptical cross-sectional shape. The lengths of its major and minor axes are determined according to the operating wavelength and the required phase retardation. The liquid crystal molecule is formed using a polymer, and after UV curing, it can form a fixed phase retardation.

[0062] It is understandable that when the anisotropic structural unit is a liquid crystal molecule, the orientation modulation layer 13 can also be a geometric phase grating structure, with a substrate or other structure, without the need for an electrode structure, simplifying the geometric phase metasurface structure and reducing costs.

[0063] In this example, the geometric phase metasurface structure has a fixed phase retardation, enabling the conversion between left-handed circularly deflected light and right-handed circularly polarized light, and the deflection of the beam can be achieved by using periodically gradient-arranged anisotropic structural units.

[0064] In some implementations, such as Figure 9 As shown, the polarization modulation layer 12 is an electrically controlled modulation layer, and the polarization modulation layer 12 has at least a first state and a second state; In the first state, the polarization modulation layer 12 maintains the polarization state of the light emitted from the display panel 11; In the second state, the polarization modulation layer 12 changes the polarization state of the light emitted from the display panel 11.

[0065] Specifically, the polarization modulation layer 12 is an electronically controlled modulation layer, having at least a first state and a second state, such that the polarization modulation layer 12 has at least two switchable phase delay values, and the polarization state of the linearly polarized light emitted from the display panel 11 is adjusted differently under different phase delay values. In the first state, the polarization state of the linearly polarized light emitted from the display panel 11 is not changed; in the second state, the polarization state of the linearly polarized light emitted from the display panel 11 is changed, converting the linearly polarized light into circularly polarized light.

[0066] In some embodiments, in the first state, the phase delay of the polarization modulation layer 12 is 0 or one wavelength; In the second state, the phase delay of the polarization modulation layer 12 is one-quarter wavelength or three-quarter wavelength.

[0067] Specifically, such as Figure 9 As shown, in the first state, the phase retardation of the polarization modulation layer 12 is 0 or λ, and the polarization modulation layer 12 does not change the polarization state of the incident light. In the second state, the phase retardation of the polarization modulation layer 12 is one-quarter wavelength (λ / 4) or three-quarter wavelength (3λ / 4). The phase retardation of λ / 4 converts linearly polarized light into left-handed circularly polarized light; the phase retardation of 3λ / 4 converts linearly polarized light into right-handed circularly polarized light, thus facilitating the subsequent deflection of the beam to the left or right viewing angle by the direction modulation layer 13. The long axis of the liquid crystal molecules within the polarization modulation layer 12 forms an angle of +45° with the polarization direction of the incident light within its plane.

[0068] It is understandable that the larger the driving voltage applied to the liquid crystal molecules, the smaller the phase delay. Thus, the driving voltages corresponding to phase delays of 0, λ / 4, 3λ / 4, and λ decrease sequentially, and a phase delay of 0 can be considered the state corresponding to the driving voltage reaching saturation.

[0069] The driving voltages corresponding to different phase delays can be obtained using the following method: A function curve corresponding to the driving voltage and phase delay of the liquid crystal cell is established in advance: different driving voltages are applied to both sides of the liquid crystal layer of the liquid crystal cell, the actual phase delay of the liquid crystal cell under each driving voltage is measured, and a function curve is established based on the correspondence between the driving voltage and the actual phase delay. Based on the target phase delay, the target driving voltage corresponding to the target phase delay is obtained by looking up the function curve. The target driving voltage includes a first voltage, a second voltage, a third voltage, and a fourth voltage, which correspond to phase delays of 0, λ / 4, λ / 2, and 3λ / 4 for the liquid crystal cell, respectively.

[0070] In this example, by pre-establishing the corresponding function curve between the driving voltage and the phase delay, the driving voltage required to achieve the target phase delay can be obtained accurately and quickly, thereby ensuring the accuracy and consistency of the liquid crystal cell phase control and improving the reliability of the electronically controlled viewing angle switching.

[0071] The polarization modulation layer 12 may have only two phase retardation values. For example, when a voltage is applied, the liquid crystal molecules deflect, the effective birefringence changes, and the phase retardation value of the polarization modulation layer 12 becomes 0. When no voltage is applied, the liquid crystal molecules maintain the initial orientation, and the phase retardation value is λ / 4. The polarization modulation layer 12 may also have three phase retardation values: 0, λ / 4, and 3λ / 4. Alternatively, the polarization modulation layer 12 may also have four phase retardation values: 0, λ / 4, 3λ / 4, and λ.

[0072] In some implementations, such as Figure 9 As shown, the polarization modulation layer 12 includes a second liquid crystal layer 131 and a second alignment layer 136. The second alignment layer 136 includes a plurality of trenches 1261. The extension direction of the plurality of trenches 1261 is consistent in a plane parallel to the display panel 11, so that the long axis direction of the plurality of liquid crystal molecules in the second liquid crystal layer 131 is consistent. The polarization modulation layer 12 is used to apply different driving voltages to the second liquid crystal layer 131 so that the polarization modulation layer 12 has at least two different phase delays.

[0073] Specifically, the polarization modulation layer 12 can be an adjustable liquid crystal cell, which has at least two different phase retardation values ​​under different driving voltages. The liquid crystal cell includes a second liquid crystal layer 131 and a second alignment layer 136. The second liquid crystal layer 131 includes multiple liquid crystal molecules, which are rod-shaped and made of birefringent material. The material of the second alignment layer 136 can be the same as or different from the material of the first alignment layer 126. The extension directions of the multiple trenches 1261 in the second alignment layer 136 are consistent in a plane parallel to the display panel 11, ensuring consistent orientation of the multiple liquid crystal molecules in the second liquid crystal layer 131. The second alignment layer 136 can be fabricated using triboelectric alignment or photoalignment techniques.

[0074] It should be noted that the liquid crystal cell also includes a third substrate 132 and a fourth substrate 133 disposed opposite to each other. The second liquid crystal layer 131 is disposed between the third substrate 132 and the fourth substrate 133. A third electrode 134 is disposed between the second liquid crystal layer 131 and the third substrate 132. A fourth electrode 135 is disposed between the fourth substrate 133 and the second liquid crystal layer 131. The third electrode 134 and the fourth electrode 135 are used to apply different driving voltages to the second liquid crystal layer 131 so that the liquid crystal cell has at least two different phase delays.

[0075] It is understandable that the phase retardation of the liquid crystal cell and the geometric phase grating is determined by the thickness d of the corresponding liquid crystal layer and the birefringence of the liquid crystal material, i.e., the phase retardation Γ = 2π × Δn × d / λ. When the liquid crystal molecules in the liquid crystal cell and the geometric phase grating are the same, since the phase retardation of the liquid crystal cell is λ / 4 and the phase retardation of the geometric phase grating is λ², the thickness of the liquid crystal layer in the liquid crystal cell is twice the thickness of the corresponding liquid crystal layer in the geometric phase grating. The thickness of the first liquid crystal layer 121 within the geometric phase grating can be 2 μm to 4 μm, or it can be set to other values ​​according to actual needs.

[0076] The liquid crystal cell may also include at least one second alignment layer 136, which is disposed between the third electrode 134 and the second liquid crystal layer 131, or the second alignment layer is disposed between the fourth electrode 135 and the second liquid crystal layer 131. Preferably, the liquid crystal layer adopts two second alignment layers 136, which are symmetrically disposed on both sides of the second liquid crystal layer 131.

[0077] It should be noted that the directional modulation layer 13 is an adjustable geometric phase grating, and the polarization modulation layer 12 is an adjustable liquid crystal cell. The substrates on the side of the geometric phase grating and the liquid crystal cell that are close to each other can share the same substrate, thereby saving one substrate and reducing costs.

[0078] In some implementations, such as Figure 14As shown, the polarization modulation layer 12 is a liquid crystal polymer film, which includes a third liquid crystal layer. The third liquid crystal layer includes a plurality of liquid crystal molecules, the long axis of which is aligned. The liquid crystal polymer film has a fixed phase retardation.

[0079] Specifically, the polarization modulation layer 12 can also be a fixed liquid crystal polymer film. The liquid crystal polymer film includes a third liquid crystal layer, in which multiple liquid crystal molecules have the same long axis direction. It is prepared by: coating a substrate with a mixed solution of reactive liquid crystal elements and a photoinitiator, followed by drying to form the liquid crystal layer; exposing the liquid crystal layer to polarized ultraviolet light to uniformly align the liquid crystal molecules along the polarization direction; and then curing it under ultraviolet light while maintaining the orientation to crosslink and fix the liquid crystal molecules. The liquid crystal polymer film has a fixed phase retardation, such as λ / 4 or λ3 / 4.

[0080] In this embodiment, the display panel 11 includes, but is not limited to, LCD display panel 11, OLED display panel 11, Micro-LED display panel 11, Mini-LED display panel 11, QLED display panel 11, etc.

[0081] like Figure 4 As shown, the display module 10 of this application also includes a backlight module 15. The backlight module 15 is disposed on the side of the display panel 11 away from the polarization modulation layer 12. A collimating prism 14 is also disposed between the backlight module 15 and the display panel 11 to collimate the diverging light of the backlight module 15 and incident it onto the display panel 11, so that the display panel 11 emits polarized light.

[0082] Example 1 like Figure 9 As shown, the light emitted from the display panel 11 is linearly polarized light. The polarization modulation layer 12 is an adjustable liquid crystal cell with a phase delay of 0 when voltage is applied and a phase delay of λ / 4 when no voltage is applied. The direction modulation layer 13 is an adjustable geometric phase grating with a phase delay of 0 when voltage is applied and a phase delay of λ / 2 when no voltage is applied. Therefore, the display module 10 has the following operating modes: 1) When no voltage is applied to the polarization modulation layer 12 (λ / 4) and no voltage is applied to the direction modulation layer 13 (λ / 2), the beam direction is deflected. Then, the linearly polarized light emitted from the display panel 11 is converted into left-hand circularly polarized light after passing through the polarization modulation layer 12. The left-hand circularly polarized light is converted into right-hand circularly polarized light after passing through the direction modulation layer 13. Finally, the linearly polarized light emitted from the display panel 11 is deflected to right-hand circularly polarized light from the left viewing angle and is not visible from other viewing angles.

[0083] 2) When voltage (0) is applied to polarization modulation layer 12 and voltage (λ / 2) is not applied to direction modulation layer 13, the beam direction is deflected. Then the linearly polarized light emitted from display panel 11 is still linearly polarized light after passing through polarization modulation layer 12. The linearly polarized light is converted into left-hand circularly polarized light and right-hand circularly polarized light after passing through direction modulation layer 13. Finally, the linearly polarized light emitted from display panel 11 is deflected to work simultaneously at the left and right viewing angles.

[0084] 3) When no voltage (λ / 4) is applied to the polarization modulation layer 12 and a voltage (0) is applied to the directional modulation layer 13, the linearly polarized light emitted from the display panel 11 is converted into left-hand circularly polarized light after passing through the polarization modulation layer 12. The left-hand circularly polarized light is still left-hand circularly polarized light after passing through the directional modulation layer 13. Finally, the linearly polarized light emitted from the display panel 11 is emitted as left-hand circularly polarized light at a positive angle.

[0085] 4) Apply voltage (0) to polarization modulation layer 12 and voltage (0) to direction modulation layer 13; then the linearly polarized light emitted from display panel 11 is still linearly polarized light after passing through polarization modulation layer 12 and linearly polarized light is still linearly polarized light after passing through direction modulation layer 13, and finally the linearly polarized light emitted from display panel 11 is linearly polarized light emitted at a positive angle.

[0086] Therefore, the display module 10 provided in this application embodiment can realize four different working modes, such as frontal view, left view, and simultaneous working of left and right views.

[0087] Example 2 like Figure 14 As shown, the light emitted from the display panel 11 is linearly polarized light. The polarization modulation layer 12 is a fixed liquid crystal polymer film with a phase retardation of λ / 4. The orientation modulation layer 13 is an adjustable geometric phase grating with a phase retardation of 0 when voltage is applied and a phase retardation of λ / 2 when no voltage is applied. Therefore, the display module 10 has the following operating modes: 1) The polarization modulation layer 12 has a fixed phase delay of λ / 4, and the direction modulation layer 13 is not subjected to voltage (λ / 2), so the beam direction is deflected; then the linearly polarized light emitted from the display panel 11 is converted into left-hand circularly polarized light after passing through the polarization modulation layer 12, and the left-hand circularly polarized light is converted into right-hand circularly polarized light after passing through the direction modulation layer 13. Finally, the linearly polarized light emitted from the display panel 11 is deflected to right-hand circularly polarized light at the left viewing angle, and is not visible at other viewing angles.

[0088] 2) The polarization modulation layer 12 has a fixed phase delay of λ / 4. When the directional modulation layer 13 is subjected to voltage (0), the linearly polarized light emitted from the display panel 11 is converted into left-hand circularly polarized light after passing through the polarization modulation layer 12. The left-hand circularly polarized light is still left-hand circularly polarized light after passing through the directional modulation layer 13. Finally, the linearly polarized light emitted from the display panel 11 is emitted as left-hand circularly polarized light at a positive angle.

[0089] Therefore, the display module 10 provided in this application embodiment can realize two different working modes: frontal view and left view.

[0090] Example 3 like Figure 13 As shown, the light emitted from the display panel 11 is linearly polarized light. The polarization modulation layer 12 is an adjustable liquid crystal cell with a phase delay of 0 when voltage is applied and a phase delay of λ / 4 when no voltage is applied. The direction modulation layer 13 is a fixed geometric phase metasurface structure with a fixed phase delay of λ / 2. Therefore, the display module 10 has the following operating modes: 1) When no voltage (λ / 4) is applied to the polarization modulation layer 12, and the directional modulation layer 13 has a fixed phase delay of λ / 2, the linearly polarized light emitted from the display panel 11 is converted into left-hand circularly polarized light after passing through the polarization modulation layer 12. The left-hand circularly polarized light is converted into right-hand circularly polarized light after passing through the directional modulation layer 13. Finally, the linearly polarized light emitted from the display panel 11 is deflected to right-hand circularly polarized light from the left viewing angle and is not visible from other viewing angles.

[0091] 2) When a voltage (0) is applied to the polarization modulation layer 12 and the directional modulation layer 13 has a fixed phase delay λ / 2, the linearly polarized light emitted from the display panel 11 is still linearly polarized light after passing through the polarization modulation layer 12. The linearly polarized light is converted into left-hand circularly polarized light and right-hand circularly polarized light after passing through the directional modulation layer 13. Finally, the linearly polarized light emitted from the display panel 11 is deflected to the left and right viewing angles and works simultaneously.

[0092] Therefore, the display module 10 provided in this application embodiment can realize two different working modes: left-viewing angle and left-viewing angle and simultaneous working of left and right-viewing angles.

[0093] Example 4 like Figure 9 As shown, the light emitted from the display panel 11 is linearly polarized light. The polarization modulation layer 12 is an adjustable liquid crystal cell, with phase delays of 0, λ / 4, λ3 / 4, and λ when voltage is applied, corresponding to a sequential decrease in the applied voltage. The direction modulation layer 13 is an adjustable geometric phase grating, with a phase delay of 0 when voltage is applied and λ / 2 when no voltage is applied. Therefore, the display module 10 has the following operating modes: 1) When the phase delay of the polarization modulation layer 12 is 0 or λ, and no voltage (λ / 2) is applied to the directional modulation layer 13, the beam direction is deflected. Then, the linearly polarized light emitted from the display panel 11 is still linearly polarized light after passing through the polarization modulation layer 12. The linearly polarized light is converted into left-hand circularly polarized light and right-hand circularly polarized light after passing through the directional modulation layer 13. Finally, the linearly polarized light emitted from the display panel 11 is deflected to work simultaneously at the left and right viewing angles.

[0094] 2) The phase delay of the polarization modulation layer 12 is 0 or λ, and the voltage (0) is applied to the directional modulation layer 13; then the linearly polarized light emitted from the display panel 11 is still linearly polarized light after passing through the polarization modulation layer 12, and the linearly polarized light is still linearly polarized light after passing through the directional modulation layer 13. Finally, the linearly polarized light emitted from the display panel 11 is emitted at a positive angle.

[0095] 3) The phase delay of the polarization modulation layer 12 is λ / 4, and the direction modulation layer 13 is not subjected to voltage (λ / 2), so the beam direction is deflected; then the linearly polarized light emitted from the display panel 11 becomes left-handed circularly polarized light after passing through the polarization modulation layer 12, and the left-handed circularly polarized light is converted into right-handed circularly polarized light after passing through the direction modulation layer 13. Finally, the linearly polarized light emitted from the display panel 11 is deflected to right-handed circularly polarized light at the left viewing angle, and is not visible at other viewing angles.

[0096] 4) The phase delay of the polarization modulation layer 12 is λ / 4, and the voltage (0) is applied to the directional modulation layer 13; then the linearly polarized light emitted from the display panel 11 becomes left-handed circularly polarized light after passing through the polarization modulation layer 12, and the left-handed circularly polarized light also becomes left-handed circularly polarized light after passing through the directional modulation layer 13. Finally, the linearly polarized light emitted from the display panel 11 is emitted as left-handed circularly polarized light at a positive angle.

[0097] 5) The phase delay of the polarization modulation layer 12 is λ3 / 4, and the direction modulation layer 13 is not subjected to voltage (λ / 2), so the beam direction is deflected; then the linearly polarized light emitted from the display panel 11 becomes right-hand circularly polarized light after passing through the polarization modulation layer 12, and the right-hand circularly polarized light is converted into left-hand circularly polarized light after passing through the direction modulation layer 13. Finally, the linearly polarized light emitted from the display panel 11 is deflected to left-hand circularly polarized light at the right viewing angle, and is not visible at other viewing angles.

[0098] 6) The phase delay of the polarization modulation layer 12 is λ3 / 4, and the voltage (0) is applied to the directional modulation layer 13; then the linearly polarized light emitted from the display panel 11 becomes right-hand circularly polarized light after passing through the polarization modulation layer 12, and the right-hand circularly polarized light also becomes right-hand circularly polarized light after passing through the directional modulation layer 13. Finally, the linearly polarized light emitted from the display panel 11 is emitted as right-hand circularly polarized light at a positive angle.

[0099] Therefore, the display module 10 provided in this application embodiment can realize six different working modes, including frontal view, left view, right view, and simultaneous working of left and right views.

[0100] In a second aspect, the present invention provides a display device comprising the display module 10 described in any embodiment of the present application.

[0101] Specifically, the display device can be a portable mobile terminal such as a mobile phone, tablet computer, laptop computer, or smartwatch; it can also be an in-vehicle display terminal such as a central control display screen, dashboard display screen, or head-up display system; it can also be a public device with privacy requirements such as an ATM, self-service terminal, cash register, or advertising machine; or it can be a wearable display device such as augmented reality glasses or virtual reality head-mounted display.

[0102] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A display module, characterized in that, include: Display panel; A dimming layer is disposed on the light-emitting side of the display panel. The dimming layer includes a polarization modulation layer and a direction modulation layer stacked together. The polarization modulation layer is disposed between the display panel and the direction modulation layer. The polarization modulation layer is used at least to adjust the polarization state of the light emitted from the display panel, and the direction modulation layer is used at least to adjust the direction of the light emitted from the polarization modulation layer. At least one of the polarization modulation layer and the orientation modulation layer is an electrically controlled modulation layer, which is used to switch between at least two different states to switch the emission angle of the light emitted from the display panel.

2. The display module according to claim 1, characterized in that, The directional modulation layer is an electronically controlled modulation layer, and the electronically controlled modulation layer has at least a first phase state and a second phase state. In the first phase state, the direction modulation layer does not generate geometric phase modulation, so that the light emitted from the display panel is emitted along the positive viewing angle direction; In the second phase state, the direction modulation layer generates geometric phase modulation to deflect the light emitted from the display panel to a preset direction, which includes a left viewing angle and / or a right viewing angle.

3. The display module according to claim 2, characterized in that, In the first phase state, the phase delay of the directional modulation layer is 0; in the second phase state, the phase delay of the directional modulation layer is half a wavelength.

4. The display module according to any one of claims 1-3, characterized in that, The orientation modulation layer is a geometric phase grating, which includes a first liquid crystal layer and at least one first alignment layer. The first alignment layer includes multiple trenches, and the extension directions of the multiple trenches are arranged in a periodic gradient in a plane parallel to the display panel. The extension directions of each trench in the same period are continuously rotated and arranged in the range of 0 to 180°, so that the long axis direction of multiple liquid crystal molecules in the first liquid crystal layer is consistent with the extension direction of the trenches. The directional modulation layer is used to apply different driving voltages to the first liquid crystal layer so that the geometric phase grating has at least two different phase delays.

5. The display module according to claim 4, characterized in that, The directional modulation layer further includes a first substrate and a second substrate disposed opposite to each other, the first liquid crystal layer being disposed between the first substrate and the second substrate; a first electrode being disposed between the first liquid crystal layer and the first substrate, and a second electrode being disposed between the first liquid crystal layer and the second substrate; the first electrode and the second electrode are used to apply different driving voltages to the first liquid crystal layer.

6. The display module according to claim 4, characterized in that, The display panel includes multiple pixel regions, each pixel region includes multiple sub-pixels of the same color, and the geometric phase grating includes multiple grating regions, each grating region is set in a one-to-one correspondence with the pixel region, and the grating period of the grating regions corresponding to pixel regions of different colors is different.

7. The display module according to claim 4, characterized in that, Within the first alignment layer, the trench arrangement period is 1μm to 20μm, the trench depth is 80nm to 200nm, and the duty cycle is (0.2~5):

1.

8. The display module according to claim 1, characterized in that, The directional modulation layer is a geometric phase metasurface structure, which includes multiple anisotropic structural units. These anisotropic structural units are arranged in a periodic, gradually changing pattern in a plane parallel to the display panel. The major axis of the anisotropic structural units within the same period is continuously rotated within the range of 0 to 180°. The geometric phase metasurface structure has a fixed phase delay.

9. The display module according to claim 8, characterized in that, The anisotropic structural unit is a liquid crystal molecule or a nanopillar.

10. The display module according to claim 1, characterized in that, The polarization modulation layer is an electronically controlled modulation layer, and the polarization modulation layer has at least a first state and a second state. In the first state, the polarization modulation layer maintains the polarization state of the light emitted from the display panel; In the second state, the polarization modulation layer changes the polarization state of the light emitted from the display panel.

11. The display module according to claim 10, characterized in that, In the first state, the phase delay of the polarization modulation layer is 0 or one wavelength; In the second state, the phase delay of the polarization modulation layer is one-quarter wavelength or three-quarter wavelength.

12. The display module according to claim 11, characterized in that, The polarization modulation layer includes a second liquid crystal layer and a second alignment layer. The second alignment layer includes a plurality of trenches. The extension direction of the plurality of trenches is consistent in a plane parallel to the display panel, so that the long axis direction of the plurality of liquid crystal molecules in the second liquid crystal layer is consistent. The polarization modulation layer is used to apply different driving voltages to the second liquid crystal layer so that the polarization modulation layer has at least two different phase delays.

13. The display module according to claim 1, characterized in that, The polarization modulation layer is a liquid crystal polymer film, which includes a third liquid crystal layer. The third liquid crystal layer includes multiple liquid crystal molecules, the long axis of which is aligned. The liquid crystal polymer film has a fixed phase retardation.

14. A display device, characterized in that, The display device includes the display module according to any one of claims 1-13.

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