Backlight structure and display module

Abstract

The invention relates to a backlight structure, which is used for providing a light source for a display panel, and comprises a light-emitting substrate, a plurality of light-emitting units and a plurality of light-emitting units, the metasurface lens array is located on the light-emitting side of the light-emitting substrate and comprises a plurality of metasurface lenses, the orthographic projection of one metasurface lens on the light-emitting substrate covers at least one light-emitting unit, and the metasurface lens is configured to converge light emitted by the corresponding at least one light-emitting unit to a preset position. The invention further relates to a backlight module.

Description

Technical Field

[0001] This invention relates to the field of display product manufacturing technology, and in particular to a backlight structure and a display module. Background Technology

[0002] In the VR field, with small-sized, ultra-high-resolution displays, when the MiniLED spacing is small, the light from adjacent LEDs may interfere with each other, causing a halo effect. This is typically masked using local dimming algorithms with pixel compensation, but it cannot completely eliminate the halo effect, thus reducing image quality. If the MiniLED spacing is too large, it may lead to a decrease in the brightness and color uniformity of the display panel.

[0003] To achieve a balance, MiniLED backlight modules stack different functional and thickness films together, aiming to ensure uniformity while absorbing light. However, since LEDs are Lambertian light sources, the divergence angle of light when the brightness of an LED drops to 50% is around 120°. Furthermore, the light passing through multiple films with different refractive indices further expands this 120° range. Based on the PSF (Point Spread Function) curve, a single lamp area is defined as the range where brightness decays from 100% to 1%. Generally, Local Dimming algorithms require a single lamp area to affect a 3×3 to 7×7 area. However, in actual 2.56-inch LCD modules, the total lamp area is 24×24. A single lamp area affects the surrounding 23×23 lamp areas, exceeding the algorithm's calculation range. This makes it impossible to process high-contrast patterns through rendering of the surrounding lamp areas and LCD masking, resulting in halos in dark areas, causing overall image unevenness and reduced image clarity.

[0004] Currently, another method involves applying adhesive to MiniLEDs, similar to adding a convex lens. However, the dispensing precision is difficult to control, and due to the small size of MiniLEDs, the adhesive overflows and forms a spherical surface, causing more stray light. Furthermore, because it relies on gravity, the shape consistency is poor, and the optical angle is uncontrollable, thus preventing its commercialization. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a backlight structure and a display module.

[0006] To achieve the above objectives, the technical solution adopted in this embodiment of the invention is: a backlight structure for providing a light source to a display panel, comprising:

[0007] A light-emitting substrate, wherein the light-emitting substrate includes a plurality of light-emitting units;

[0008] A metasurface lens array, located on the light-emitting side of the light-emitting substrate, includes multiple metasurface lenses. The orthogonal projection of one of the metasurface lenses onto the light-emitting substrate covers at least one light-emitting unit. The metasurface lens is configured to converge the light emitted by the corresponding at least one light-emitting unit.

[0009] Optionally, the light-emitting unit includes at least one LED.

[0010] Optionally, the metasurface lens array includes an adjacent first row of metasurface lenses and a second row of metasurface lenses, wherein multiple metasurface lenses in the first row and multiple metasurface lenses in the second row are arranged alternately.

[0011] Optionally, the metasurface lens includes a transparent substrate and a plurality of microstructures disposed on the transparent substrate.

[0012] Optionally, the microstructures are arranged as multiple concentric ring structures.

[0013] Optionally, the metasurface lens is a geometric phase metasurface lens, and the microstructure is a nanofin, wherein the rotation angle of each nanofin is proportional to the phase change of light passing through the geometric phase metasurface lens.

[0014] Optionally, the phase of the light rays at each light-emitting position in the metasurface lens Satisfy the following formula:

[0015]

[0016] Where f is the focal length of the metasurface lens, r is the distance from any of the nanofins in the metasurface lens to the center point of the metasurface lens, and λ d n is the wavelength of the incident light. d is the refractive index of the metasurface lens.

[0017] Optionally, when the incident light is blue light, the rotation angle of the nanofins of the multiple ring structures in the metasurface lens is set from 0 to 0.96π in an increasing gradient of 0.22nπ in the direction outward from the center point of the metasurface lens, and the spacing between two adjacent ring structures is m micrometers, where m = 1 / n and n is a rational number.

[0018] Optionally, when the incident light is green light, the rotation angle of the nanofins of the multiple ring structures in the metasurface lens is set from 0 to 0.96π in an increasing gradient of 0.19nπ in the direction outward from the center point of the metasurface lens, and the spacing between two adjacent ring structures is m micrometers, where n is a rational number and m = 1 / n.

[0019] Optionally, when the incident light is red light, the rotation angle of the nanofins of the multiple ring structures in the metasurface lens is set from 0 to 0.85π in an increasing gradient of 0.16nπ in the direction outward from the center point of the metasurface lens, and the distance between two adjacent ring structures is m micrometers, where n is a rational number and m = 1 / n.

[0020] Optionally, the metasurface lens array includes a first metasurface unit, a second metasurface unit, and a third metasurface unit, wherein the first metasurface unit is configured to modulate the phase of red light, the second metasurface unit is configured to modulate the phase of green light, and the third metasurface unit is configured to modulate the phase of blue light.

[0021] The first metasurface unit, the second metasurface unit, and the third metasurface unit can be arranged along the row direction of the metasurface lens array, or along the column direction of the metasurface lens array, or arranged in a triangular structure.

[0022] Optional,

[0023] In the direction perpendicular to the transparent substrate, the height of the nanofin is greater than or equal to the wavelength of the incident light. In the direction parallel to the transparent substrate, the length L of the nanofin is 0.35-0.55 times the height H of the nanofin, and the width W of the nanofin is 0.2-0.3 times the height H of the nanofin.

[0024] Optionally, the metasurface lens is a phase-transmission metasurface lens, and the microstructure is a nanopillar, the diameter of each nanopillar being proportional to the phase change of light passing through the phase-transmission metasurface lens.

[0025] Optionally, each of the annular structures includes multiple nanopillar rings in the direction outward from the center point of the metasurface lens, and the radii of the cross-sections of the multiple nanopillar rings are arranged in decreasing order.

[0026] Optionally, the phase of the metasurface lens Satisfy the following formula:

[0027]

[0028] Where f is the focal length of the metasurface lens, r is the distance from any of the nanopillars in the metasurface lens to the center point of the metasurface lens, and λ d n is the wavelength of the incident light. d is the refractive index of the metasurface lens.

[0029] Optionally, a plurality of grooves are provided on the first surface of the transparent substrate, the center point of the grooves coincides with the center point of the annular structure, and the extending direction of the grooves is parallel to the radial direction of the annular structure;

[0030] Each groove has a slide rail at its bottom. Along the extension direction of the groove, the slide rail includes multiple spaced connection areas. Multiple nanopillars are movably disposed in each connection area. A magnetic connection part is disposed at one end of each nanopillar near the slide rail. A movement control unit including an electromagnetic solenoid is disposed in each connection area. The movement control unit is configured to control the movement of the corresponding nanopillar by changing the intensity and direction of the current.

[0031] Optionally, an electromagnetic shielding structure may be provided between adjacent connection areas.

[0032] Optionally, the microstructure may contain quantum dot particles at one end away from the transparent substrate, the quantum dot particles being excited by blue light to produce red and green light.

[0033] Optionally, the light-emitting side of the metasurface lens is provided with a diffusion structure.

[0034] This invention also provides a display module, including the backlight structure described above.

[0035] The beneficial effects of this invention are: reducing the inherent refractive index of traditional film materials such as prism sheets and diffusers, thus preventing excessive halo caused by multiple refractions and reflections of the MiniLED light source; the backlight structure provided by this invention features ultra-thin characteristics, customizable optical path capabilities, small color difference, and superior imaging quality. It is suitable for future high-PPI, small-aperture VR LCD modules, significantly improving contrast, brightness, and color uniformity. Attached Figure Description

[0036] Figure 1 A schematic diagram illustrating a metasurface lens;

[0037] Figure 2 A schematic diagram showing the light-emitting substrate;

[0038] Figure 3 A schematic diagram illustrating a metasurface lens;

[0039] Figure 4 A schematic diagram showing nanofins;

[0040] Figure 5 A schematic diagram showing nanofins;

[0041] Figure 6 A schematic diagram illustrating the modulation principle of a geometric phase metasurface lens;

[0042] Figure 7 Schematic diagram of a metasurface lens;

[0043] Figure 8 Schematic diagram of a metasurface lens;

[0044] Figure 9 express Figure 8 Enlarged schematic diagram of the nanopillars within the dashed box;

[0045] Figure 10 A schematic diagram showing an electromagnetic solenoid;

[0046] Figure 11 This diagram illustrates the movement control of the nanopillar.

[0047] Figure 12 A schematic diagram illustrating the movement of the nanopillar. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0049] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an,” “a,” or “the,” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “including,” “comprising,” or “containing,” and similar terms mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. The terms “connected,” “linked,” or similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” and “right,” etc., are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described objects changes.

[0050] The features such as "parallel," "perpendicular," and "identical" used in the embodiments of this disclosure include features in the strict sense of "parallel," "perpendicular," and "identical," as well as cases where "approximately parallel," "approximately perpendicular," and "approximately identical" include certain tolerances. Taking into account the measurement and the tolerances associated with the measurement of a specific quantity (e.g., limitations of the measurement system), they represent the acceptable deviation range for a specific value as determined by a person skilled in the art. For example, "approximately" can mean within one or more standard deviations, or within 3% or 5% of said value.

[0051] Two-dimensional metasurface lenses are planar optical elements that utilize periodically arranged unit structures on a subwavelength scale to focus and manipulate light waves. These unit structures are typically made of metals, dielectrics, or other materials and can be precisely designed to achieve specific optical functions. The working principle of two-dimensional metasurface lenses can be summarized in the following aspects:

[0052] Subwavelength unit structure: Metasurface lenses are composed of many subwavelength unit structures, which can be circular, square, hexagonal or other shapes.

[0053] Phase control: Each unit structure is equivalent to a phase delayer. By precisely designing the size, shape and geometric arrangement of the unit structure, the phase delay of the light wave passing through each unit can be controlled.

[0054] Wavefront reshaping: By adjusting the phase delay of the unit cell structure, metasurface lenses can reshape the wavefront of incident light waves, causing them to focus on the other side of the lens. This wavefront reshaping is key to the focusing function of metasurface lenses.

[0055] Amplitude and polarization control: In addition to phase control, metasurface lenses can also adjust the amplitude of light waves by designing the transmittance or reflectance of the unit structure, and manipulate the polarization state of light waves through specific structural designs.

[0056] Focusing efficiency: The focusing efficiency of a metasurface lens depends on the design, arrangement, and manufacturing precision of its unit cell structure. Ideally, all incident light waves can be effectively focused to a single point.

[0057] Beyond the diffraction limit: Due to the subwavelength resolution of metasurface lenses, they can achieve imaging resolution that exceeds the traditional optical diffraction limit.

[0058] Planar and lightweight: Compared to traditional spherical lenses, metasurface lenses are planar, which makes them lighter, thinner, and easier to integrate into compact optical systems.

[0059] Multifunctionality: Metasurface lenses can not only be used for focusing, but can also be designed to have other optical functions, such as beam shaping, beam steering, holographic imaging, etc.

[0060] Tunability: Some metasurface lens designs can achieve dynamic tunability, changing their optical properties through external control (such as voltage, temperature, or mechanical stress).

[0061] refer to Figures 1-12 In this embodiment, a metasurface structure is used for dimming to improve dimming accuracy.

[0062] Specifically, this embodiment provides a backlight structure for providing a light source to a display panel, including:

[0063] A light-emitting substrate, wherein the light-emitting substrate includes a plurality of light-emitting units;

[0064] A metasurface lens array, located on the light-emitting side of the light-emitting substrate, includes multiple metasurface lenses. The orthogonal projection of one of the metasurface lenses onto the light-emitting substrate covers at least one light-emitting unit. The metasurface lens is configured to converge the light emitted by the corresponding at least one light-emitting unit to a preset position.

[0065] In this embodiment, a metasurface lens array is used to achieve the dimming function, so that the light emitted by the light-emitting substrate is focused at a preset position, which is the human eye. Compared with the multi-layer film stacking in the traditional structure, it has the characteristics of being ultra-thin and improving the dimming accuracy.

[0066] In an exemplary embodiment, the light-emitting unit includes at least one LED lamp 10.

[0067] In traditional MiniLED backlight designs, multi-layer optical films are typically required to achieve uniform illumination and reduce halo effects. This not only increases system complexity and cost but can also lead to losses and aberrations in the optical path. This invention employs two-dimensional metasurface technology to improve MiniLED backlight performance in a more compact and efficient manner.

[0068] For example, the light-emitting substrate includes a plurality of LEDs 10 arranged in an array, and adjacent rows or columns of LEDs 10 are staggered in the row or column direction of the array arrangement, as shown in the reference. Figure 2 This allows the arranged light patterns to cover the gaps as much as possible, and the lighting area is rendered by independently controlled pulse width modulation (PWM dimming) to improve uniformity.

[0069] For example, the backlight structure includes multiple sub-pixels, and each light-emitting unit can correspond to one of the sub-pixels.

[0070] For example, the metasurface lens array includes an adjacent first row of metasurface lenses and a second row of metasurface lenses, wherein a plurality of metasurface lenses in the first row of metasurface lenses and a plurality of metasurface lenses in the second row of metasurface lenses are alternately arranged.

[0071] For example, the metasurface lens includes a transparent substrate 1 and a plurality of microstructures 2 disposed on the transparent substrate 1. The microstructures 2 can be formed by electron beam lithography (EBL) or nanoimprint lithography (NIL).

[0072] For example, the plurality of microstructures 2 are arranged as a plurality of concentric ring structures 20, as shown in the reference. Figure 3 and Figure 8 .

[0073] refer to Figures 3-6 For example, the metasurface lens is a geometric phase metasurface lens, and the microstructure 2 is a nanofin. The rotation angle of each nanofin is proportional to the phase change of light passing through the geometric phase metasurface lens.

[0074] For example, the phase of the light rays at each light-emitting position in the metasurface lens Satisfy the following formula:

[0075]

[0076] Where f is the focal length of the metasurface lens, r is the distance from any of the nanofins in the metasurface lens to the center point of the metasurface lens, and λ d n is the wavelength of the incident light. d is the refractive index of the metasurface lens.

[0077] It should be noted that when the metasurface lens is a geometric phase type metasurface, the light emitted by the light-emitting substrate is circularly polarized light. For example, a quarter-wave plate is provided on the light-emitting side of the LED lamp.

[0078] The modulation principle of a geometric phase-type metasurface lens: When circularly polarized light is incident on the surface of the metalens, it passes through a subwavelength grating fin structure. Specifically, in the direction perpendicular to the transparent substrate, the height of the nanofin is greater than or equal to the wavelength of the incident light; in the direction parallel to the transparent substrate, the length L of the nanofin is 0.35-0.55 times the height H of the nanofin, and the width W of the nanofin is 0.2-0.3 times the height H of the nanofin. In some implementations, H is set to 430-760nm (the specific range is not limited to visible light; this example only considers adaptation to RGB color light wavelengths), L is set to 150-410nm, and W is set to 40-85nm. It should be noted that blue light has a wavelength of 430-450nm, green light has a wavelength of 500-560nm, and red light has a wavelength of 610-760nm. To achieve better light modulation, different H values ​​can be selected for different incident light (e.g., in the case of multi-color light, the average or median wavelength can be used), i.e., different subwavelength grating fin structures can be chosen. For example, when the incident light is blue light, the H value can be 430-450nm.

[0079] (refer to Figure 4 The additional phase shift modulation is converted into a spherical wave, thereby achieving beam convergence (e.g., Figure 6 The radius of an ideal converging spherical wavelet:

[0080]

[0081] f is the focal length of the designed metasurface lens, and the phase delay at any point can be expressed as:

[0082]

[0083] Where k is the magnitude of the wave vector of light in the transmission medium. Therefore, the phase distribution of the metasurface lens in polar coordinates can be expressed as:

[0084]

[0085] In the formula, r is the distance from any point A of the metasurface lens to the center point O of the metasurface lens (reference). Figure 6 ); λ is the incident light wavelength; n d is the refractive index of the metasurface lens.

[0086] Geometric phase modulation process: Circularly polarized light is irradiated onto the subwavelength grating fin structure (i.e., the nanofins) (e.g.) Figure 4 The emitted light is modulated into circularly polarized light with opposite chirality. The phase shift depends on the rotation direction of the anisotropic structure on the nanofins of the metasurface lens, and is numerically equal to twice the rotation angle of the structure. Therefore, by arranging the nanofins at rotation angles of 0-π, phase modulation of 0-2π can be achieved, precisely controlling the rotation angle θ of the nanofins at a given coordinate point (x, y). nf (x,y) (e.g.) Figure 5 ), can be represented as:

[0087]

[0088] For example, the metasurface lens is made of titanium dioxide, which has a high refractive index, enabling precise control of the light wave propagation path and phase compensation of the light wave incident at a large angle on the MiniLED, thus achieving the effect of focusing and shaping light.

[0089] For example, the focal length f of the metasurface lens is set to 10 mm, and the refractive index n of the metasurface lens made of titanium dioxide is... d Approximately 1, the metasurface lens can modulate light of different wavelengths, improving the accuracy of light modulation.

[0090] When the incident light is blue light, the rotation angle of the nanofins of the multiple ring structures 20 in the metasurface lens is set from 0 to 0.96π in an increasing gradient of 0.22nπ in the direction outward from the center point of the metasurface lens, and the spacing between two adjacent ring structures 20 is m micrometers, where n is a rational number and m = 1 / n.

[0091] When the incident light is green light, the rotation angle of the nanofins of the multiple ring structures 20 in the metasurface lens is set from 0 to 0.96π in an increasing gradient of 0.19nπ in the direction outward from the center point of the metasurface lens, and the spacing between two adjacent ring structures 20 is m micrometers, where n is a rational number and m = 1 / n.

[0092] When the incident light is red light, the rotation angle of the nanofins of the multiple ring structures 20 in the metasurface lens is set from 0 to 0.85π in an increasing gradient of 0.16nπ in the direction outward from the center point of the metasurface lens, and the spacing between two adjacent ring structures 20 is m micrometers, where n is a rational number and m = 1 / n.

[0093] For example, the metasurface lens array includes a first metasurface unit, a second metasurface unit, and a third metasurface unit, wherein the first metasurface unit is configured to modulate the phase of red light, the second metasurface unit is configured to modulate the phase of green light, and the third metasurface unit is configured to modulate the phase of blue light.

[0094] The first metasurface unit, the second metasurface unit, and the third metasurface unit can be arranged along the row direction of the metasurface lens array, or along the column direction of the metasurface lens array, or arranged in a triangular structure.

[0095] For example, in the direction perpendicular to the transparent substrate 1, the height H of the nanofin is 600 nm, the length L of the nanofin is 150-410 nm, and the width W of the nanofin is 40-85 nm.

[0096] refer to Figures 7-12 For example, the metasurface lens is a transmission phase type metasurface lens, and the microstructure 2 is a nanopillar, the diameter of each nanopillar being proportional to the phase change of light passing through the transmission phase type metasurface lens.

[0097] For example, the cross-sectional shape of the nanopillar can be circular, polygonal, etc., and is not limited herein.

[0098] For example, in the direction outward from the center point of the metasurface lens, each of the annular structures 20 includes multiple nanopillar rings 200, and the radii of the cross-sections of the nanopillars within the multiple nanopillar rings 200 are arranged in decreasing order.

[0099] In the radial direction of the ring structure 20, multiple nanopillars are periodically arranged, with multiple nanopillars in each period forming a ring structure 20. The height of the nanopillars is generally designed to be on the order of wavelength. When multiple nanopillars have the same height, phase modulation from 0 to 2π is achieved by changing the cross-sectional area or duty cycle of the nanopillars. For example, if the incident light is 455 nm wavelength (i.e., blue light), multiple nanopillars of the same height can be used, with the height of the nanopillars potentially selected as 800 nm. In the radial direction of the multiple ring structures 20, the radius of the cross-section of the nanopillar within the multiple rings 200 is λ - (λ - ma), where λ is the wavelength of the incident light, m ​​is the number of rings in one ring structure 20, and a is the spacing between two adjacent rings of nanopillars in one ring structure 20.

[0100] Taking blue light as an example, in the radial direction of the plurality of ring structures 20, the spacing between adjacent nanopillars 200 within each ring structure 20 corresponds to the incident wavelength (455nm), which is 32.5nm. In the radial direction of the plurality of ring structures 20, they are arranged from the center of the metasurface lens to the far-end coordinate point (x,y) (e.g.) Figure 3 As shown), the cross-sectional radius of the nanopillars within the multiple nanopillar rings 200 can be selected as 455-227.5 nm, with a step size a of 32.5 nm. Figure 4(Partial enlarged schematic diagram) Each of the circular ring structures 20 may include 8 nanopillar rings 200 (i.e., m is 8).

[0101] For example, the phase of the metasurface lens Satisfying the formula:

[0102]

[0103] Where f is the focal length of the metasurface lens, r is the distance from any of the nanopillars in the metasurface lens to the center point of the metasurface lens, and λ d n is the wavelength of the incident light. d is the refractive index of the metasurface lens.

[0104] In an exemplary embodiment, when the metasurface lens is a phase-transfer metasurface lens, the phase of the metasurface lens can also be adjusted by adjusting the height of the nanopillars.

[0105]

[0106] Where n is the refractive index of the metasurface lens and h is the height of the nanocylinder.

[0107] refer to Figures 10-12 In an exemplary embodiment, a plurality of grooves are provided on the first surface of the transparent substrate 1, the center point of the grooves coincides with the center point of the annular structure 20, and the extending direction of the grooves is parallel to the radial direction of the annular structure 20.

[0108] Each groove has a slide rail at its bottom. Along the extension direction of the groove, the slide rail includes multiple spaced connection areas. Multiple nanopillars are movably disposed in each connection area. A magnetic connection part is disposed at one end of each nanopillar near the slide rail. A movement control unit including an electromagnetic solenoid 30 is disposed in each connection area. The movement control unit is configured to control the movement of the corresponding nanopillar by changing the intensity and direction of the current.

[0109] By adopting the above scheme, the position of the nanopillars in the radial direction of the annular structure 20 can be adjusted, that is, the spacing between adjacent nanopillar rings 200 can be adjusted, thereby realizing the adjustable modulation phase of light.

[0110] For example, an electromagnetic solenoid (nanometer-scale) 30 can be made using a graphene nanospiral structure (reference). Figure 10The electromagnetic solenoid 30 can be made of a conductive metal, such as gold nanotubes (AuNT). The magnetic field B within the solenoid 30 is given by the formula μnj. The magnetic field strength depends on the current j and the number of turns per unit length n. When n remains constant, the magnetic field strength can be adjusted by changing the current j, thereby adjusting the displacement of the nanopillar. The direction of movement of the nanopillar can be determined by adjusting the direction of the current.

[0111] For example, an electromagnetic shielding structure is provided between adjacent connection regions. This prevents the current electromagnetic solenoid 30 from affecting the adjacent nanopillars.

[0112] For example, the nanopillars within the same ring move synchronously, the movement control units within the multiple connection areas are controlled independently, and the movement of the multi-ring nanopillar ring 200 can be controlled in a time-division manner. That is, the multi-ring nanopillar ring 200 includes a first ring nanopillar ring 201. When the position of the first ring nanopillar ring 201 is moved, the other nanopillars except for the first ring nanopillar ring 201 remain fixed, and the current of the electromagnetic solenoid in the corresponding movement control unit is zero, so as to avoid mutual interference between the movement of nanopillars in different rings.

[0113] refer to Figure 11 When an electric current is applied to the electromagnetic solenoid 30, the nanopillar 2 moves back and forth between positions M1 and M2 under the action of a magnetic field. Figure 12 The figure shows the positional relationship between the position of a nanopillar before and after the movement of one of the nanopillars in the first ring of nanopillars 201.

[0114] For example, the end of the microstructure 2 away from the transparent substrate 1 is provided with quantum dot particles, which are used to be excited by blue light to generate red and green light.

[0115] Using the above solution, the LEDs on the light-emitting substrate can be blue LEDs.

[0116] For example, the metasurface lens has a diffusion structure on the light-emitting side to further improve the light distribution and reduce the halo effect.

[0117] This invention also provides a display module, including the backlight structure described above.

[0118] The backlight structure has a display panel on its light-emitting side, and the display panel can be a liquid crystal panel.

[0119] The following points need to be explained:

[0120] (1) The accompanying drawings of the embodiments of this disclosure only involve the structures involved in the embodiments of this disclosure. Other structures can be referred to the general design.

[0121] (2) For clarity, the thickness of layers or regions is enlarged or reduced in the drawings used to describe embodiments of the present disclosure, i.e., these drawings are not drawn to actual scale. It will be understood that when an element such as a layer, film, region or substrate is referred to as being “above” or “below” another element, the element may be “directly” located “above” or “below” the other element or there may be intermediate elements.

[0122] (3) Where there is no conflict, the embodiments of this disclosure and the features in the embodiments can be combined with each other to obtain new embodiments.

[0123] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A backlight structure for providing a light source to a display panel, characterized in that, include: A light-emitting substrate, wherein the light-emitting substrate includes a plurality of light-emitting units; A metasurface lens array, located on the light-emitting side of the light-emitting substrate, includes multiple metasurface lenses. The orthogonal projection of one of the metasurface lenses onto the light-emitting substrate covers at least one light-emitting unit. The metasurface lens is configured to converge the light emitted by the corresponding at least one light-emitting unit.

2. The backlight structure according to claim 1, characterized in that, The light-emitting unit includes at least one LED light.

3. The backlight structure according to claim 1, characterized in that, The metasurface lens array includes an adjacent first row of metasurface lenses and a second row of metasurface lenses, with multiple metasurface lenses in the first row and multiple metasurface lenses in the second row being arranged alternately.

4. The backlight structure according to claim 1, characterized in that, The metasurface lens includes a transparent substrate and a plurality of microstructures disposed on the transparent substrate.

5. The backlight structure according to claim 4, characterized in that, The microstructures are arranged in multiple concentric ring structures.

6. The backlight structure according to claim 5, characterized in that, The metasurface lens is a geometric phase metasurface lens, and the microstructure is a nanofin. The rotation angle of each nanofin is proportional to the phase change of light passing through the geometric phase metasurface lens.

7. The backlight structure according to claim 6, characterized in that, The light phase at each light-emitting position in the metasurface lens Satisfy the following formula: Where f is the focal length of the metasurface lens, r is the distance from any of the nanofins in the metasurface lens to the center point of the metasurface lens, and λ d n is the wavelength of the incident light. d is the refractive index of the metasurface lens.

8. The backlight structure according to claim 7, characterized in that, When the incident light is blue light, the rotation angle of the multiple ring-shaped nanofins in the metasurface lens is set from 0 to 0.96π in an increasing gradient of 0.22nπ in the direction outward from the center point of the metasurface lens, and the spacing between two adjacent ring structures is m micrometers, where n is a rational number and m = 1 / n.

9. The backlight structure according to claim 7, characterized in that, When the incident light is green light, the rotation angle of the multiple ring-shaped nanofins in the metasurface lens is set from 0 to 0.96π in an increasing gradient of 0.19nπ in the direction outward from the center point of the metasurface lens, and the spacing between two adjacent ring structures is m micrometers, where n is a rational number and m = 1 / n.

10. The backlight structure according to claim 7, characterized in that, When the incident light is red light, the rotation angle of the multiple ring-shaped nanofins in the metasurface lens is set from 0 to 0.85π in an increasing gradient of 0.16nπ in the direction outward from the center point of the metasurface lens, and the distance between two adjacent ring structures is m micrometers, where n is a rational number and m = 1 / n.

11. The backlight structure according to claim 6, characterized in that, The metasurface lens array includes a first metasurface unit, a second metasurface unit, and a third metasurface unit. The first metasurface unit is configured to modulate the phase of red light, the second metasurface unit is configured to modulate the phase of green light, and the third metasurface unit is configured to modulate the phase of blue light. The first metasurface unit, the second metasurface unit, and the third metasurface unit can be arranged along the row direction of the metasurface lens array, or along the column direction of the metasurface lens array, or arranged in a triangular structure.

12. The backlight structure according to claim 6, characterized in that, In the direction perpendicular to the transparent substrate, the height of the nanofin is greater than or equal to the wavelength of the incident light. In the direction parallel to the transparent substrate, the length L of the nanofin is 0.35-0.55 times the height H of the nanofin, and the width W of the nanofin is 0.2-0.3 times the height H of the nanofin.

13. The backlight structure according to claim 5, characterized in that, The metasurface lens is a phase-transmission type metasurface lens, and the microstructure is a nanopillar. The diameter of each nanopillar is proportional to the phase change of light passing through the phase-transmission type metasurface lens.

14. The backlight structure according to claim 13, characterized in that, In the direction outward from the center point of the metasurface lens, each of the annular structures includes multiple nanopillar rings, and the radius of the cross-section of the nanopillars within the multiple nanopillar rings is arranged in decreasing order.

15. The backlight structure according to claim 13, characterized in that, The phase of the metasurface lens Satisfy the following formula: Where f is the focal length of the metasurface lens, r is the distance from any of the nanopillars in the metasurface lens to the center point of the metasurface lens, and λ d n is the wavelength of the incident light. d is the refractive index of the metasurface lens.

16. The backlight structure according to claim 13, characterized in that, The first surface of the transparent substrate is provided with a plurality of grooves, the center point of the grooves coincides with the center point of the annular structure, and the extension direction of the grooves is parallel to the radial direction of the annular structure; Each groove has a slide rail at its bottom. Along the extension direction of the groove, the slide rail includes multiple spaced connection areas. Multiple nanopillars are movably disposed in each connection area. A magnetic connection part is disposed at one end of each nanopillar near the slide rail. A movement control unit including an electromagnetic solenoid is disposed in each connection area. The movement control unit is configured to control the movement of the corresponding nanopillar by changing the intensity and direction of the current.

17. The backlight structure according to claim 16, characterized in that, An electromagnetic shielding structure is provided between adjacent connection areas.

18. The backlight structure according to claim 4, characterized in that, Quantum dot particles are disposed at one end of the microstructure away from the transparent substrate. These quantum dot particles are used to be excited by blue light to generate red and green light.

19. The backlight structure according to claim 1, characterized in that, The metasurface lens has a diffusion structure on its light-emitting side.

20. A display module, characterized in that, Includes the backlight structure according to any one of claims 1-19.

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