Backlight source and display device

Abstract

The invention discloses a backlight source and a display device. In the backlight source, a light source (100) comprises a light emitting unit (110); the light-transmitting substrate (200) is located on the light-emitting side of the light source (100). The first lens group (300) comprises a plurality of first lenses (310) and is positioned on the light emitting side of the light-transmitting substrate (200); the second lens group (400) comprises a plurality of second lenses (410) and is located on the light incident side of the light-transmitting substrate (200). The maximum size of the first lens (310) and the maximum size of the second lens (410) in the direction parallel to the light-transmitting substrate (200) are the first size (D1) and the second size (D2) respectively, and the first size (D1) is larger than the second size (D2). The orthographic projection of the second lens (410) on the light-transmitting substrate (200) is overlapped with the outline of the orthographic projection of the first lens (310) on the light-transmitting substrate (200) or is located in a gap between the orthographic projections of the adjacent first lenses (310) on the light-transmitting substrate (200); the maximum size of each light-emitting unit (110) in the direction parallel to the light-transmitting substrate (200) is a third size (D3), the ratio of the second size (D2) to the third size (D3) is 0.2-0.5, and the ratio of the second size (D2) to the first size (D1) is 0.04-0.2.

Description

Backlight source and display device

[0001] The embodiments of the present disclosure relate to a backlight source and a display device.

[0002] Virtual reality (VR) display is gradually becoming a hot field. In order to reduce the granularity of the display image, the resolution of the display screen needs to be generally greater than 1500ppi, or even higher, such as greater than 3000ppi. For a display screen with such a high pixel density (ppi), its pixel transmittance will be seriously reduced. For example, the pixel transmittance of the display screen used in virtual reality display devices is generally less than 2%, which will directly lead to an increase in the backlight brightness and even an increase in the overall power consumption of the module.

[0003]

[0004] The present disclosure provides a backlight source and a display device.

[0005] The backlight source provided by the present disclosure includes: a light source, a transparent substrate, a first lens group and a second lens group. The light source includes a plurality of light-emitting units; the transparent substrate is located at the light-emitting side of the light source; the first lens group is located at the light-emitting side of the transparent substrate, and the first lens group includes a plurality of first lenses; the second lens group is located at the light-entering side of the transparent substrate, and the second lens group includes a plurality of second lenses. The maximum size of each first lens in a direction parallel to the transparent substrate is a first size, and the maximum size of each second lens in a direction parallel to the transparent substrate is a second size, the first size is greater than the second size, and the orthographic projection of at least one second lens on the transparent substrate overlaps with the contour of the orthographic projection of at least one first lens on the transparent substrate or is located in the interval between the orthographic projections of adjacent first lenses on the transparent substrate; the maximum size of each light-emitting unit in a direction parallel to the transparent substrate is a third size, the ratio of the second size to the third size is 0.2 to 0.5, and the ratio of the second size to the first size is 0.04 to 0.2.

[0006] For example, according to an embodiment of the present disclosure, the ratio of the first size to the pitch between adjacent light emitting units is 0.7 to 1.3.

[0007] For example, according to an embodiment of the present disclosure, the distance between the optical axis of at least one first lens and the optical axis of the second lens closest to the optical axis of the at least one first lens is less than 15 micrometers.

[0008] For example, according to an embodiment of the present disclosure, the multiple first lenses are arranged in one-to-one correspondence with the multiple light-emitting units, and the orthographic projection of each first lens on the light-transmitting substrate overlaps with the orthographic projection of at least two second lenses on the light-transmitting substrate, the first lens with overlapping orthographic projections, the light-transmitting substrate and the at least two second lenses constitute an optical structure, and the distance between at least one light-emitting unit and the focal plane of the optical structure corresponding to it is not greater than 50 microns.

[0009] For example, according to an embodiment of the present disclosure, the plurality of first lenses are closely arranged, and the plurality of second lenses are closely arranged.

[0010] For example, according to an embodiment of the present disclosure, the shape of the orthographic projection of each first lens on the light-transmitting substrate includes a hexagon, there is basically no gap between the orthographic projections of adjacent first lenses on the light-transmitting substrate, and the orthographic projection of at least one second lens on the light-transmitting substrate overlaps with the outline of the orthographic projections of at least two first lenses on the light-transmitting substrate.

[0011] For example, according to an embodiment of the present disclosure, the shape of the orthographic projection of each first lens on the transparent substrate includes a circle, and the gap between the orthographic projections of any adjacent first lenses on the transparent substrate overlaps with the orthographic projection of at least one second lens on the transparent substrate.

[0012] For example, according to an embodiment of the present disclosure, the shape of the orthographic projection of each first lens on the light-transmitting substrate includes a circle, a gap is provided between the orthographic projections of any adjacent first lenses on the light-transmitting substrate, and the orthographic projection of at least one second lens on the light-transmitting substrate is completely located within the gap.

[0013] For example, according to an embodiment of the present disclosure, the geometric center of the gap falls within the orthographic projection of a second lens on the light-transmitting substrate, and the orthographic projection of the second lens on the light-transmitting substrate is completely located within the gap.

[0014] For example, according to an embodiment of the present disclosure, the geometric center of the gap falls within the orthographic projection of a second lens on the transparent substrate, and the orthographic projection of the second lens on the transparent substrate overlaps or is tangent to the orthographic projection of the first lens on the transparent substrate.

[0015] For example, according to an embodiment of the present disclosure, each light emitting unit is configured to emit white light.

[0016] For example, according to an embodiment of the present disclosure, at least one light-emitting unit includes sub-light-emitting units of different colors.

[0017] For example, according to an embodiment of the present disclosure, the ratio of the thickness of the light-transmitting substrate to the maximum dimension of the second lens in a direction perpendicular to the light-transmitting substrate is 8-20.

[0018] For example, according to an embodiment of the present disclosure, the first lens includes a plano-convex lens, the second lens includes a plano-convex lens, and the plane of the first lens and the plane of the second lens are both facing the light-transmitting substrate.

[0019] For example, according to an embodiment of the present disclosure, both the first lens and the second lens include spherical lenses.

[0020] For example, according to an embodiment of the present disclosure, a ratio of a radius of curvature of the first lens to the first size is 0.4-0.6, and a ratio of the first size to a maximum size of the first lens in a direction perpendicular to the light-transmitting substrate is 1.5-6.

[0021] For example, according to an embodiment of the present disclosure, a ratio of a radius of curvature of the second lens to the second size is 0.4-0.6, and a ratio of the second size to the maximum size of the second lens in a direction perpendicular to the light-transmitting substrate is 2-7.

[0022] For example, according to an embodiment of the present disclosure, the refractive index of the first lens is greater than the refractive index of the light-transmitting substrate.

[0023] For example, according to an embodiment of the present disclosure, the refractive index of the second lens is greater than the refractive index of the light-transmitting substrate.

[0024] For example, according to an embodiment of the present disclosure, the angle of light emitted by the backlight source is ±α degrees, and α is not greater than 5.

[0025] An embodiment of the present disclosure provides a display device, comprising a display panel and any of the above-mentioned backlight sources, wherein the display panel is located at a light emitting side of the backlight source.

[0026] For example, according to an embodiment of the present disclosure, the display panel includes a plurality of sub-pixels, the maximum size of each sub-pixel in a direction parallel to the light-transmitting substrate is a fourth size, and the distance between adjacent first lenses is smaller than the fourth size.

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present disclosure, but are not intended to limit the present disclosure.

[0028] FIG. 1 is an optical path diagram of a display device using VR technology.

[0029] FIG. 2 is a partial structural diagram of a collimated backlight source.

[0030] FIG. 3 is a schematic diagram of a partial cross-sectional structure of a backlight source provided according to an embodiment of the present disclosure.

[0031] FIG. 4A is a schematic diagram of a partial planar structure of a light source in a backlight source provided according to an embodiment of the present disclosure in one example.

[0032] 4B and 4C are schematic diagrams of the planar structure of a light emitting unit in different examples.

[0033] FIG. 5 is a light path diagram of a first lens, a second lens, and a light-transmitting substrate in the backlight source shown in FIG. 3 .

[0034] FIG. 6 is a light path diagram of a first lens, a second lens, and a light-transmitting substrate in a backlight source in another example.

[0035] FIG. 7 is a light path diagram when only the first lens is provided in the backlight source.

[0036] FIG. 8 is a light path diagram of an optical structure consisting of a first lens, a light-transmitting substrate, and a plurality of second lenses in the backlight source shown in FIG. 3 .

[0037] FIG. 9 is a graph showing the relationship between the convergence angles corresponding to light-emitting units of different sizes when matching the structures shown in FIG. 7 and FIG. 8 at different sizes.

[0038] FIG. 10 is a graph showing the effect of the air gap between the second lens and the light source on the focusing angle and uniformity of the backlight source.

[0039] FIG. 11 is a graph showing the effect of the air gap between the second lens and the light source on the light efficiency of the backlight source.

[0040] 12 is a graph showing the effect of the thickness variation of the light-transmitting substrate on the collimation angle and brightness uniformity of the backlight source when the second lens has different second sizes.

[0041] FIG. 13 is a graph showing the effect of the thickness variation of the light-transmitting substrate on the light effect when the second lens has different second sizes.

[0042] 14 is a graph showing the effect of the thickness variation of the light-transmitting substrate on the collimation angle and brightness uniformity of the backlight source when the second lens has different second sizes.

[0043] FIG. 15 is a graph showing the effect of the thickness variation of the light-transmitting substrate on the light effect when the second lens has different second sizes.

[0044] FIG. 16 is a brightness distribution diagram when only the first lens is provided in the backlight source shown in FIG. 7 .

[0045] FIG. 17A is an orthographic projection relationship diagram of a portion of the first lens, a portion of the second lens, and a portion of the light emitting unit of the backlight source shown in FIG. 3 in one example.

[0046] 17B is an orthographic projection relationship diagram of a portion of the first lens, a portion of the second lens, and a portion of the light emitting unit of the backlight source shown in FIG. 3 in another example.

[0047] 17C is an orthographic projection relationship diagram of a portion of the first lens, a portion of the second lens, and a portion of the light emitting unit in yet another example of the backlight source shown in FIG. 3 .

[0048] FIG. 18 is a diagram showing the brightness distribution of the backlight source shown in FIG. 17A .

[0049] FIG. 19 is an orthographic projection relationship diagram of a portion of the first lens, a portion of the second lens, and a portion of the light emitting unit of the backlight source shown in FIG. 3 in another example.

[0050] FIG. 20 is a diagram showing the brightness distribution of the backlight source shown in FIG. 19 .

[0051] FIG. 21 is a graph showing the relationship between the focusing angle and brightness of the backlight source shown in FIG. 3 .

[0052] FIG. 22 is a partial structural diagram of a display device provided according to another embodiment of the present disclosure.

[0053] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0054] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Including" or "comprising" and similar words mean that the elements or objects appearing in front of the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. The features such as "parallel", "vertical" and "same" used in the embodiments of the present disclosure include the features such as "parallel", "vertical", "same" in the strict sense, and "approximately parallel", "approximately vertical", "approximately the same" and other situations containing certain errors, taking into account the measurement and the errors related to the measurement of a specific amount (for example, the limitations of the measurement system), indicating the acceptable deviation range for a specific value determined by ordinary technicians in the field. For example, "approximately" can be expressed within one or more standard deviations, or within 10% or 5% of the value. When the number of a component is not particularly indicated in the following of the embodiments of the present disclosure, it means that the component can be one or more, or can be understood as at least one. "At least one" refers to one or more, and "multiple" refers to at least two.

[0055] Figure 1 is a light path diagram of a display device using VR technology. As shown in Figure 1, the display device includes a display panel and a backlight source 001 and a lens group 002 located on the light-emitting side of the display panel and the backlight source 001. For example, the lens group 002 can adopt a folded light path (Pancake).

[0056] During the study, the inventors of the present application found that the pixel transmittance of the display panel shown in FIG1 is only 2%. For the lens group 002 using the Pancake optical path, the light efficiency is about 20%. The brightness required for human viewing is at least 100 nits (nit), so the backlight brightness required is 100÷0.2÷0.02=25000nit. Therefore, the required backlight brightness is 2 to 5 times that of ordinary backlight, resulting in higher power consumption of the backlight source.

[0057] A display device using pixel-level dimming technology, such as adding a dimming lens at the bottom of the pixel, deflects the light that originally enters the non-light-transmitting area and is blocked into the light-transmitting area, such as the opening of the black matrix, through the dimming lens, thereby increasing the amount of light transmitted, which can solve the above-mentioned problem of high backlight power consumption.

[0058] However, by setting the maximum thickness of the dimming lens to 3.5 microns, the dimming lens is a plano-convex lens, and the refractive index of the dimming lens is 1.8 as an example, the gain changes with the height of the dimming lens. It can be seen that: when the light output angle of the backlight source is 20 degrees, the maximum gain does not exceed 120%; when the light output angle of the backlight source is 10 degrees, the maximum gain can reach 150%. It can be seen that only when the backlight source has a high degree of collimation, such as when the light output angle is within the range of ±5 degrees, the overall light efficiency of the display device using pixel-level dimming technology can be greatly improved.

[0059] FIG. 2 is a partial structural diagram of a collimated backlight source. As shown in FIG. 2 , the collimated light source includes a light source plate 035, a diffuse structure 034 located on the light-emitting side of the light source plate 035, a light conversion structure 033, a light-collecting structure 032, and a collimating structure 031. For example, the light source plate 035 includes a plurality of light sources, a reflective layer, and a driving circuit board. For example, a light mixing distance OD is provided between the light source and the diffuse structure 034. For example, the light conversion structure 033 includes a quantum dot conversion layer, such as converting blue light into red light or green light. For example, the diffuse structure 034 may include a diffuser plate. For example, the collimating structure 031 may include structures such as a prism layer and a brightness enhancement film. As shown in FIG. 2 , the sum of the thicknesses from the collimating structure 031 to the diffuse structure 034 is approximately 0.97 mm, the light mixing distance on the light-emitting side of the light source plate 035 is approximately 0.5 mm, and the thickness of the light source plate 035 is approximately 0.22 mm. Thus, the thickness of the collimated backlight source is approximately 1.7 mm.

[0060] The disclosed embodiment provides a backlight source and a display device. The backlight source includes a light source, a transparent substrate, a first lens group and a second lens group. The light source includes a plurality of light-emitting units; the transparent substrate is located on the light-emitting side of the light source; the first lens group is located on the light-emitting side of the transparent substrate, and the first lens group includes a plurality of first lenses; the second lens group is located on the light-entering side of the transparent substrate, and the second lens group includes a plurality of second lenses. The maximum size of each first lens in a direction parallel to the transparent substrate is a first size, the maximum size of each second lens in a direction parallel to the transparent substrate is a second size, the first size is greater than the second size, the orthographic projection of at least one second lens on the transparent substrate overlaps with the outline of the orthographic projection of at least one first lens on the transparent substrate or is located in the interval between the orthographic projections of adjacent first lenses on the transparent substrate; the maximum size of each light-emitting unit in a direction parallel to the transparent substrate is a third size, the ratio of the second size to the third size is 0.2 to 0.5, and the ratio of the second size to the first size is 0.04 to 0.2.

[0061] In the backlight source provided by the present disclosure, by respectively arranging the first lens and the second lens on both sides of the light-transmitting substrate, and setting the relative position relationship between the first lens and the second lens, the first size of the first lens, the second size of the second lens and the third size relationship of the light-emitting unit, the backlight source can have high collimation and high uniformity.

[0062] The backlight source and the display device provided by the embodiments of the present disclosure are described below in conjunction with the accompanying drawings.

[0063] Fig. 3 is a schematic diagram of a partial cross-sectional structure of a backlight source provided according to an embodiment of the present disclosure. Fig. 4A is a schematic diagram of a partial planar structure of a light source in a backlight source provided according to an embodiment of the present disclosure in an example.

[0064] As shown in Figures 3 and 4A, the backlight source includes a light source 100, a transparent substrate 200, a first lens group 300 and a second lens group 400. The light source 100 includes a plurality of light emitting units 110. For example, the plurality of light emitting units 110 may be arranged in an array along the X direction and the Z direction.

[0065] As shown in FIG3 , the light-transmitting substrate 200 is located at the light-emitting side of the light source 100 . For example, the light-transmitting substrate 200 may be a solid substrate or a hollow substrate. For example, an air gap is provided between the light-transmitting substrate 200 and the light source 100 .

[0066] As shown in FIG3 , the first lens group 300 is located on the light exiting side of the light-transmitting substrate 200, such as the first lens group 300 is located on the side of the light-transmitting substrate 200 away from the light source 100. The first lens group 300 includes a plurality of first lenses 310. The second lens group 400 is located on the light incident side of the light-transmitting substrate 200, such as the second lens group 400 is located between the light-transmitting substrate 200 and the light source 100. The second lens group 400 includes a plurality of second lenses 410.

[0067] As shown in FIG3 , the maximum size of each first lens 310 in a direction parallel to the light-transmitting substrate 200 is a first size D1, and the maximum size of each second lens 410 in a direction parallel to the light-transmitting substrate 200 is a second size D2, and the first size D1 is greater than the second size D2. The light-transmitting substrate 200 includes a principal plane perpendicular to the Y direction, and the direction parallel to the light-transmitting substrate 200 may be a direction parallel to the principal plane. For example, the number of the second lenses 410 is greater than the number of the first lenses 310. The first size D1 of the first lens 310 may be the aperture of the first lens 310, and the second size D2 of the second lens 410 may be the aperture of the second lens 410. For example, the shape of the orthographic projection of the first lens 310 on the light-transmitting substrate 200 may be a circle, and the first size D1 is the diameter of the circle. The shape of the orthographic projection of the second lens 410 on the light-transmitting substrate 200 may also be a circle, and the second size D2 may be the diameter of the circle. For example, the shape of the orthographic projection of the first lens 310 on the transparent substrate 200 can also be other shapes, such as polygons such as quadrilaterals, pentagons, hexagons, octagons, etc., and the first size D1 can be the length of the longest diagonal in the polygon. For example, the shape of the orthographic projection of the second lens 320 on the transparent substrate 200 can also be other shapes, such as polygons such as quadrilaterals, pentagons, hexagons, octagons, etc., and the second size can be the length of the longest diagonal in the polygon. The present disclosure takes the maximum size of each first lens in the direction parallel to the transparent substrate as strictly equal, that is, the first size is strictly equal as an example. Considering the process error, the first size of different first lenses may have a certain difference, such as the certain difference is not greater than 10% of the first size. The present disclosure takes the maximum size of each second lens in the direction parallel to the transparent substrate as strictly equal, that is, the second size is strictly equal as an example. Considering the process error, the second size of different second lenses may have a certain difference, such as the certain difference is not greater than 10% of the second size.

[0068] As shown in FIG3 , the orthographic projection of at least one second lens 410 on the light-transmitting substrate 200 overlaps with the outline of the orthographic projection of at least one first lens 310 on the light-transmitting substrate 200 or is located in the interval between the orthographic projections of adjacent first lenses 310 on the light-transmitting substrate 200. For example, the outline of the orthographic projection of each first lens 310 on the light-transmitting substrate 200 overlaps with the orthographic projections of the plurality of second lenses 410 on the light-transmitting substrate 200. For example, the orthographic projection of the center of at least one first lens 310 on the light-transmitting substrate 200 falls within the orthographic projection of the second lens 410 on the light-transmitting substrate 200. For example, the orthographic projection of at least one first lens 310 on the light-transmitting substrate 200 overlaps with the orthographic projections of at least two second lenses 410 on the light-transmitting substrate 200.

[0069] As shown in FIG. 3 and FIG. 4A , the maximum dimension of each light-emitting unit 110 in a direction parallel to the light-transmitting substrate 200 is a third dimension D3, the ratio of the second dimension D2 to the third dimension D3 is 0.2 to 0.5, and the ratio of the second dimension D2 to the first dimension D1 is 0.04 to 0.2. For example, the third dimension D3 may be the maximum dimension of the light-emitting area of ​​the light-emitting unit 110 in a direction parallel to the light-transmitting substrate. For example, the shape of the light-emitting area may be a polygon, and the third dimension D3 may be the length of the diagonal of the light-emitting area. The present disclosure takes the maximum dimension of each light-emitting unit in a direction parallel to the light-transmitting substrate, that is, each third dimension is strictly equal, as an example. Taking into account the process error, there may be a certain difference in the third dimensions of different light-emitting units, such as the certain difference is not greater than 10% of the third dimension.

[0070] In some examples, as shown in FIG3 , the angle of the light emitted by the backlight source is ±α degrees, and α is not greater than 5. For example, α can be 5, or 4.9, or 4.8, or 4.7, or 4.6, or 4.5, etc. For example, the light uniformity of the backlight source is not less than 83.3%. For example, the light uniformity of the backlight source is not less than 85%.

[0071] In the backlight source provided by the present disclosure, by respectively arranging a first lens and a second lens on both sides of a light-transmitting substrate, and arranging the second lens to overlap with the contour edge of the first lens or overlap with the gap between adjacent first lenses, the first size of the first lens, the second size of the second lens and the third size relationship of the light-emitting unit are arranged, so that the backlight source can have a high collimation within a light output angle of ±5° and a high uniformity of not less than 83.3%.

[0072] Compared with the backlight source shown in Figure 2, the backlight source provided by the present invention adopts the first lens group as a collimating structure, realizes the diffusion and focusing functions through the second lens group, and reduces the mixed light distance through the cooperation of the first lens group and the second lens group, which is beneficial to reducing the thickness of the backlight source, such as reducing the thickness of the backlight source to 1.5 mm, or even below 1.1 mm, and the thickness reduction can reach 40%.

[0073] Applying the backlight source with high collimation provided by the present invention to the display device as shown in FIG1 and matching it with a display panel with a pixel-level dimming function is beneficial to improving the brightness of the display device, such as increasing the brightness gain multiplier by 1.5, and reducing the power consumption of the display device, such as reducing the power consumption by 30%, thereby improving the overall device life.

[0074] For example, as shown in Fig. 3, the ratio of the second dimension D2 to the third dimension D3 is 1 / 5 to 1 / 3, and the ratio of the second dimension D2 to the first dimension D1 is 1 / 15 to 1 / 9. For example, the ratio of the second dimension D2 to the third dimension D3 is 0.24 to 0.4, and the ratio of the second dimension D2 to the first dimension D1 is 0.05 to 0.15.

[0075] 3 , each first lens 310 has the same shape and size, and each second lens 410 has the same shape and size. For example, each first lens 310 has the same refractive index, and each second lens 410 has the same refractive index.

[0076] For example, as shown in FIG3 , the second lens 410 can be made on the surface of the transparent substrate 200. However, the invention is not limited thereto. In other examples, the second lens can be made on other substrates and then attached to the surface of the transparent substrate.

[0077] 3, the distance between the optical axis of at least one first lens 310 and the optical axis of the second lens 410 closest to the optical axis of the at least one first lens 310 is less than 15 micrometers. For example, the optical axis of the first lens 310 and the optical axis of the second lens 410 are both perpendicular to the light-transmitting substrate 200, such as extending along the Y direction.

[0078] For example, as shown in FIG3 , the distance between the optical axis of at least one first lens 310 and the optical axis of the second lens 410 is less than 10 micrometers. For example, the distance between the optical axis of at least one first lens 310 and the optical axis of the second lens 410 is less than 5 micrometers. For example, the optical axis of at least one first lens 310 coincides with the optical axis of the second lens 410. For example, the optical axis of each first lens 310 coincides with the optical axis of the corresponding second lens 410, which is conducive to ensuring that the vertex of the emission spectrum corresponds to the 0° position.

[0079] In some examples, as shown in FIGS. 3 and 4A , the ratio of the first dimension D1 to the pitch P of adjacent light-emitting units 110 is 0.7 to 1.3. The pitch P of adjacent light-emitting units 110 may refer to the length of the line connecting the centers of adjacent light-emitting units 110. For example, the ratio of the first dimension D1 to the pitch P of adjacent light-emitting units 110 is 0.9 to 1.2. For example, the ratio of the first dimension D1 to the pitch P of adjacent light-emitting units 110 is 0.8 to 1.1. For example, the ratio of the first dimension D1 to the pitch P of adjacent light-emitting units 110 is 0.95 to 1.05. For example, the first dimension D1 is equal to the pitch of adjacent light-emitting units 110 to improve the light efficiency and ensure the brightness uniformity of the light-emitting surface.

[0080] For example, as shown in FIG. 3 , adjacent light emitting units 110 may refer to adjacent light emitting units 110 arranged along the X direction, or may refer to adjacent light emitting units 110 arranged along a direction perpendicular to the XY plane.

[0081] In some examples, as shown in FIG3 , the plurality of first lenses 310 are disposed in a one-to-one correspondence with the plurality of light emitting units 110. For example, the number of the plurality of first lenses 310 is the same as the number of the plurality of light emitting units 110.

[0082] In some examples, as shown in FIG. 3 , the first lens 310 includes a plano-convex lens, the second lens 410 includes a plano-convex lens, and the planes of the first lens 310 and the second lens 410 are both facing the light-transmitting substrate 200 .

[0083] In some examples, as shown in FIG. 3 and FIG. 4A, each light-emitting unit 110 is configured to emit white light. For example, each light-emitting unit 110 includes a color light-emitting diode 111 and a color conversion layer 112, and the color conversion layer 112 wraps the light-emitting diode 111 so that the non-white light emitted by the light-emitting diode 111 is converted into white light through the color conversion layer 112. For example, a color light-emitting diode 111 can be a blue light-emitting diode. For example, the color conversion layer 112 can include quantum dot materials, or color conversion materials such as phosphors. For example, the shape of the light-emitting unit 110 can be a rectangle, and the third dimension D3 can be the diagonal dimension of the light-emitting area formed by the light emitted by the color conversion layer 112. For example, the distance M between the edge of the color conversion layer 112 and the edge of the light-emitting diode 111 can be 15 microns. Of course, the shape of the light-emitting area is not limited to a rectangle, and can also be a regular shape such as a circle, an ellipse, a triangle, a rhombus, a pentagon, a hexagon, an octagon, or other irregular shapes, such as a rounded polygon, a shape with curved edges, etc. The above-mentioned third dimension can be the diameter of a circle, the major axis of an ellipse, the longest diagonal of other polygons, etc.

[0084] 4B and 4C are schematic diagrams of the planar structure of a light emitting unit in different examples.

[0085] For example, as shown in FIG. 4B and FIG. 4C, at least one light-emitting unit 110 includes sub-light-emitting units 101 of different colors. Each light-emitting unit 110 includes light-emitting diodes 101 of different colors to emit white light. For example, each light-emitting unit 110 may include a red light-emitting diode, a green light-emitting diode, and a blue light-emitting diode. For example, the red light-emitting diode, the green light-emitting diode, and the blue light-emitting diode may be arranged in a tiled manner as shown in FIG. 4B, or may be arranged in a tiled manner as shown in FIG. 4C. For example, the third dimension D3 of the light-emitting unit 110 may be the maximum dimension of the light-emitting area 102 formed by the red light-emitting diode, the green light-emitting diode, and the blue light-emitting diode, such as the shape of the light-emitting area 102 may be a rectangle, and the third dimension D3 is the length of the diagonal of the rectangle. Of course, the present disclosure is not limited thereto, and sub-light-emitting units of different colors may also be arranged perpendicular to the XZ plane shown in FIG. 4B. At this time, the shapes of the light-emitting areas of the sub-light-emitting units of different colors may be the same, and the orthographic projections on the XZ plane coincide, and the third dimension is the maximum dimension of one of the light-emitting areas, such as the diagonal dimension, the circular diameter, etc.

[0086] For example, the distance S between adjacent light-emitting diodes 101 in the same light-emitting unit 110 shown in FIG4B and FIG4C is greater than the value of the distance M shown in FIG4A , for example, S may be 75 micrometers. Therefore, light-emitting units with different structures may have different sizes, and the size of the light-emitting unit emitting white light is an influencing factor of the sizes of the first lens and the second lens.

[0087] For example, as shown in FIG. 3 to FIG. 4C, for light-emitting units with the same light effect, the larger the size of the light-emitting unit, the larger the corresponding pitch (Pitch) to meet the same backlight brightness. The backlight brightness Lbl of the backlight source satisfies the relationship: Lbl = N*Le*Ae / (P*P), where N is the required number of light-emitting units, Le is the brightness of the light-emitting unit, Ae is the light-emitting area of ​​the light-emitting unit, and P is the pitch between adjacent light-emitting units. It can be seen that the larger P is, the smaller N is required, and for light-emitting units with the same light effect, the corresponding power consumption will be lower.

[0088] FIG. 5 is a light path diagram of a first lens, a second lens, and a light-transmitting substrate in the backlight source shown in FIG. 3 .

[0089] In some examples, as shown in FIGS. 3 and 5 , the first lens 310 and the second lens 410 each include a plano-convex lens including a spherical surface.

[0090] For example, as shown in FIG. 5 , the first lens 310 may be in direct contact with the light-transmitting substrate 200 .

[0091] For example, as shown in FIG5 , the aperture D1 of the first lens 310 can be determined as the pitch of adjacent light-emitting units by power consumption, backlight brightness, and optoelectronic characteristics of the light-emitting unit, and then the collimated light is traced from the center to the aperture edge of the first lens 310 in the reverse direction so that each light ray falls within the aperture D2 of the second lens 410 , and the aperture D2 of the second lens 410 is determined by the refractive index n2, the radius of curvature R, the aperture D1, the arch height H, the thickness T2 of the transparent substrate 200 , the refractive index n3, and the refractive index n1 of the medium other than the first lens 310 and the transparent substrate 200 .

[0092] For example, as shown in FIG5 , the angle between the light incident on the edge of the first lens 310 and the tangent line of the curved surface of the first lens 310 is θ1, the light is perpendicular to the surface of the transparent substrate 200, the angle between the light and the normal line of the curved surface of the first lens 310 is θ2, and the light is refracted during the incident process into the first lens 310, and the refraction angle is θ3. The angle between the light incident on the first lens 310 and the normal line of the surface of the transparent substrate 200 is θ5, and the light is refracted during the incident process into the transparent substrate 200, and the refraction angle is θ6. The distance between the position where the light is incident on the first lens 310 and the surface of the transparent substrate 200 close to the first lens 310 is h, and twice the distance between the position and the highest point of the first lens 310 in the direction parallel to the transparent substrate 200 is D. According to the geometric relationship and Snell’s law, the following relationships can be obtained: θ1=arccos[(D / 2) / R] (1) θ2=π / 2-θ1 (2) θ3=arcsin[(n1*sinθ2) / n2] (3) θ4=θ1+θ3 (4) θ5=π / 2-θ4 (5) θ6=arcsin[(n2*sinθ5) / n3] (6) W1=(D1-D) / 2 (7) h=H-{R-[R 2 -(D / 2) 2 ] -2} (8) W2=h*tanθ5 (9) W3=T2*tanθ6 (10) D2=D1-2*(W1+W2+W3) (11)

[0093] Substituting the relevant parameters in the above-mentioned equations (1)-(10) into the equation (11), a value of D2 can be obtained. For the collimated light rays incident on different positions of the first lens 310, multiple D2 values ​​can be obtained by tracing, among which the largest D2 value is the aperture value that can be adopted by the second lens 410. The aperture value is the aperture D2 of the second lens 410 corresponding to a set of parameters when the refractive index n2, the curvature radius R, the aperture D1, the arch height H, the thickness T2 of the transparent substrate 200, the refractive index n3 and the refractive index n1 of the medium other than the first lens 310 and the transparent substrate 200 are used.

[0094] For example, as shown in FIG5 , the first lens 310 and the light-transmitting substrate 200 can be made of two materials, and the refractive indexes n2 and n3 are determined values. Assuming that the medium outside the first lens 310 and the light-transmitting substrate 200 is air, the refractive index n1 is also determined. At this time, the minimum D2 value can be obtained by adjusting the thickness T2 of the light-transmitting substrate 200, the radius of curvature R of the first lens 310, and the arch height H, and the value of the D2 can be used as the minimum value that can be selected for the aperture D2 of the second lens 410. For example, in the process of adjusting the thickness T2 of the light-transmitting substrate 200, the radius of curvature R of the first lens 310, and the arch height H, it is also necessary to consider the influence of the aperture of the second lens on the collimation and brightness uniformity of the backlight source, as well as the processing technology of the second lens, so the aperture of the second lens may be equal to the above minimum value, or it may be greater than the above minimum value.

[0095] FIG. 6 is a light path diagram of a first lens, a second lens, and a light-transmitting substrate in a backlight source in another example.

[0096] For example, as shown in FIG6 , a spacer layer 320 is disposed between the first lens 310 and the light-transmitting substrate 200. The difference between the backlight source shown in FIG6 and the backlight source shown in FIG5 is that a spacer layer 320 is disposed between the first lens 310 and the light-transmitting substrate 200, such as the first lens 310 can be made on the spacer layer 320, and the spacer layer 320 is attached to the surface of the light-transmitting substrate 200.

[0097] For example, as shown in FIG6 , the aperture D1 of the first lens 310 can be determined as the pitch of adjacent light-emitting units by power consumption, backlight brightness, and optoelectronic characteristics of the light-emitting units, and then the collimated light is traced in reverse from the center to the aperture edge of the first lens 310 so that each light ray falls within the aperture D2 of the second lens 410 , and the aperture D2 of the second lens 410 is determined by the refractive index n2, the radius of curvature R, the aperture D1, the arch height H, the thickness T1 and the refractive index n4 of the spacer layer 320 , the thickness T2 and the refractive index n3 of the light-transmitting substrate 200 , and the refractive index n1 of the medium other than the first lens 310 and the light-transmitting substrate 200 .

[0098] For example, as shown in FIG6 , the angle between the light incident on the edge of the first lens 310 and the tangent line of the curved surface of the first lens 310 is θ1, the light is perpendicular to the surface of the spacer layer 320, the angle between the light and the normal line of the curved surface of the first lens 310 is θ2, and the light is refracted during the incident process into the first lens 310, and the refraction angle is θ3. The angle between the light incident on the first lens 310 and the normal line of the surface of the spacer layer 320 is θ5, and the light is refracted during the incident process into the spacer layer 320, and the refraction angle is θ6. The angle between the normal lines of the surface of the light-transmitting substrate 200 is θ6, and the light is refracted during the incident process into the light-transmitting substrate 200, and the refraction angle is θ7. The arch height of the first lens 310 is H, the distance between the position where the light is incident on the first lens 310 and the surface of the spacer layer 320 close to the first lens 310 is h, and twice the distance between the position and the highest point of the first lens 310 in the direction parallel to the light-transmitting substrate 200 is D. According to the geometric relationship and Snell's law, the following relationships can be obtained: θ1=arccos[(D / 2) / R] (1') θ2=π / 2-θ1 (2') θ3=arcsin[(n1*sinθ2) / n2] (3') θ4=θ1+θ3 (4') θ5=π / 2-θ4 (5') θ6=arcsin[(n2*sinθ5) / n4] (6') θ7=arcsin[(n4*sinθ6) / n3] (7') W1=(D1-D) / 2 (8') h=H-{R-[R 2 -(D / 2) 2 ] -2} (9') W2=h*tanθ5 (10') W4=T1*tanθ6 (11') W3=T2*tanθ7 (12') D2=D1-2*(W1+W2+W3+W4) (13')

[0099] Substituting the relevant parameters in the above-mentioned equations (1')-(12') into equation (13'), a value of D2 can be obtained. For the collimated light rays incident on different positions of the first lens 310, multiple D2 values ​​can be obtained by tracing, among which the largest D2 value is the aperture value that can be adopted by the second lens 410. The aperture value is the aperture D2 of the second lens 410 corresponding to a group of parameters including the refractive index n2, the curvature radius R, the aperture D1, the arch height H, the thickness T2 of the transparent substrate 200, the refractive index n3, the thickness T1 of the spacer layer 320, the refractive index n4, and the refractive index n1 of the medium other than the first lens 310 and the transparent substrate 200.

[0100] For example, as shown in FIG5 , the first lens 310, the spacer layer 320 and the light-transmitting substrate 200 can be made of three materials, and the refractive indices n2, n4 and n3 are determined values. Assuming that the medium other than the first lens 310 and the spacer layer 320 is air, the refractive index n1 is also determined. At this time, by adjusting the thickness T1 of the spacer layer 320 and the thickness T2 of the light-transmitting substrate 200, the radius of curvature R of the first lens 310 and the value of the arch height H, the minimum D2 value can be obtained, and the D2 value can be used as the minimum value that can be selected for the aperture D2 of the second lens 410. For example, in the process of adjusting the thickness T1 of the spacer layer 320, the thickness T2 of the light-transmitting substrate 200, the radius of curvature R of the first lens 310 and the value of the arch height H, it is also necessary to consider the influence of the aperture of the second lens on the collimation and brightness uniformity of the backlight source, as well as the processing technology of the second lens, so the aperture of the second lens may be equal to the above minimum value, or it may be greater than the above minimum value.

[0101] Therefore, in the examples shown in FIG. 5 and FIG. 6 , by adjusting various parameters based on comprehensive consideration of various factors, the ratio of the second size of the second lens to the third size of the light-emitting unit is 0.2 to 0.5, and the ratio of the second size of the second lens to the first size of the first lens is 0.04 to 0.2.

[0102] Fig. 7 is a light path diagram when only the first lens is provided in the backlight source. Fig. 8 is a light path diagram of an optical structure composed of a first lens, a transparent substrate and a plurality of second lenses in the backlight source shown in Fig. 3 .

[0103] For example, as shown in FIG7 , when the first lens 310 is disposed on one side of the light-transmitting substrate 200 and the second lens 410 is not disposed on the other side of the light-transmitting substrate 200, the focal plane F1 has a large deviation from the ideal focal plane F0 due to the existence of field curvature. In addition, the aperture angle α1 in this structure is small, and the distance between the ideal focal plane F0 and the object side principal surface QH1, such as the focal length f1, is large. In order to reduce the focal length of the backlight source shown in FIG7 , it is possible to consider disposing another lens on the other side of the light-transmitting substrate where the first lens is not disposed, and the number of the lenses is the same as the number of the first lenses, and the diameter of the lenses is equivalent to the diameter of the first lenses.

[0104] For example, as shown in FIG8 , relative to the backlight source shown in FIG7 , by disposing a second lens 410 on the other side of the transparent substrate 200, the offset distance between the focal plane F2 and the ideal focal plane F0 can be reduced. Thus, the optical structure composed of the second lens 410, the transparent substrate 200 and the first lens 310 can correct the field curvature, so that each position of the focal surface F2 is as close to the ideal focal plane F0 as possible, and collimated emission for light-emitting units of larger sizes can be achieved; and the focal surface F2 has a plurality of peaks close to the ideal focal plane F0, which has a light deflection effect. For example, in addition to allowing the light source point located on the optical axis to collimate the emitted light, it can also allow the light source points that are off-axis and located near the peaks of the focal surface F2 close to the ideal focal plane F0 to collimate the emitted light, thereby improving the collimation of the light emitted from the first lens and realizing the scattering function, homogenizing the energy distribution, and improving and ensuring uniformity.

[0105] For example, as shown in FIG8 , relative to setting lenses with the same number and equivalent aperture as the first lenses on the other side of the light-transmitting substrate where the first lenses are not set, the backlight source provided by the present disclosure sets a plurality of second lenses with smaller apertures on the other side of the light-transmitting substrate. This can achieve short focus while breaking up the light, thereby improving the uniformity of the light emitted by the backlight source, and can ensure that the light emitted by the light-emitting unit with an angle of more than ±80° can be incident on the corresponding first lens.

[0106] For example, as shown in FIG8 , compared with the backlight source shown in FIG7 , by providing the second lens 410, the focal length f2 between the ideal focal plane F0 and the object side principal surface QH2 is reduced, that is, the optical focal length of the optical structure composed of the second lens 410, the light-transmitting substrate 200 and the first lens 310 is increased. For example, the optical focal length of the first lens 310 is 1 / f01, and the optical focal length of the second lens 410 is 1 / f02. The optical focal length of the optical structure satisfies 1 / f=1 / f01+1 / f02, so as to achieve a short-focus effect, such as causing the object side principal surface QH2 of the optical structure to be pulled toward the light source, thereby increasing the aperture angle α2, enhancing the focusing ability of the optical structure, and being beneficial to improving the light effect while compressing the light mixing distance between the light source and the second lens, thereby reducing the thickness of the backlight source.

[0107] FIG. 9 is a graph showing the relationship between the convergence angles corresponding to light-emitting units of different sizes when matching the structures shown in FIG. 7 and FIG. 8 at different sizes.

[0108] For example, as shown in FIG9 , the L1 line, the L2 line, and the L3 line all represent curves of a structure in which only the first lens is provided in the backlight source, and the L4 line, the L5 line, and the L6 line represent curves of a structure in which the first lens and the second lens shown in FIG3 are provided in the backlight source, and the curvature radius of the first lens corresponding to the L1 line and the L4 line is 0.3 mm, the curvature radius of the first lens corresponding to the L2 line and the L5 line is 0.6 mm, and the curvature radius of the first lens corresponding to the L3 line and the L6 line is 0.9 mm. Each of the above curves corresponds to one first lens.

[0109] For example, as shown in FIG9 , when a single first lens has the same aperture, such as when the radius of curvature of the first lens is 0.6 mm, it can be seen that when the L2 line and the L5 line meet the convergence angle of less than 5°, the diagonal size of the light-emitting unit required in the backlight source with only the first lens cannot exceed 145 microns, while the diagonal size of the light-emitting unit required in the backlight source with the first lens and the second lens is not greater than 330 microns. For example, when selecting a light-emitting unit, the light-emitting unit shown in FIG4B to FIG4C can be selected, or the light-emitting unit shown in FIG4A can be selected; when selecting the light-emitting unit shown in FIG4B to FIG4C , since the spacing S is about 75 microns, in the backlight source with only the first lens, the actual light-emitting width of the light-emitting unit is less than 70 microns, while in the backlight source with the first lens and the second lens, the actual light-emitting width of the light-emitting unit can reach more than 200 microns. Therefore, the backlight source including the first lens and the second lens shown in FIG3 can adopt a larger light-emitting unit while achieving high collimation, which is conducive to reducing power consumption. The above convergence angle can also be called the collimation angle.

[0110] In some examples, as shown in FIGS. 3 and 5 , the radius of curvature R of the first lens 310 is equal to 0.4 to 0.6 of the first dimension D1, and the ratio of the first dimension D1 to the maximum dimension H of the first lens 310 in the direction perpendicular to the light-transmitting substrate 200 is 1.5 to 6. For example, the ratio of the first dimension D1 to the maximum dimension H of the first lens 310 in the direction perpendicular to the light-transmitting substrate 200 is 1.6 to 4. For example, the ratio of the first dimension D1 to the maximum dimension H of the first lens 310 in the direction perpendicular to the light-transmitting substrate 200 is 1.7 to 3. For example, the ratio of the first dimension D1 to the maximum dimension H of the first lens 310 in the direction perpendicular to the light-transmitting substrate 200 is 1.8 to 5. For example, the ratio of the first dimension D1 to the maximum dimension H of the first lens 310 in the direction perpendicular to the light-transmitting substrate 200 is 1.9 to 2.1. For example, the first dimension D1 (aperture D1) of the first lens 310 is twice the radius of curvature R. For example, the first dimension D1 is twice the thickness H of the first lens 310 .

[0111] For example, as shown in FIG3 and FIG5, in order to improve the light energy utilization rate of the light-emitting unit 110 at a large angle, it is necessary to reduce the focal length f of the optical structure composed of the first lens 310, the transparent substrate 200 and the second lens 410, and the focal length f is determined by the relationship 1 / f=1 / f10+1 / f20. For example, in the process of determining the aperture D2 of the second lens 410 in the examples shown in FIG5 and FIG6, the curvature radius R of the first lens 310 can be optimized as much as possible; for example, on the one hand, considering the process factors, the curvature radius R and the aperture D1 of the first lens 310 need to satisfy the relationship: R≥D1 / 2; on the other hand, according to the focal length formula of the plano-convex lens, f=R / Δn, where Δn represents the refractive index difference between the first lens 310 and other media (such as air), and the focal length of the first lens 310 is proportional to the curvature radius R. In order to reduce the focal length f of the above optical structure, the first lens 310 should be selected to have a focal length as small as possible, and the curvature radius R of the first lens 310 should also be selected to have a smaller value. Therefore, taking into account the process factors and the short focus factor, the radius of curvature of the first lens is as close to half of the aperture as possible.

[0112] For example, as shown in FIG5 , the maximum size H (such as arch height or center thickness), the radius of curvature R, and the aperture D1 of the first lens 310 satisfy the relationship: 2 =(RH) 2 +(D1 / 2) 2 According to the numerical relationship between the radius of curvature R and the aperture D1, the thickness H of the first lens is approximately half of the aperture D1. D1 / H is an indicator of the processing capability of the first lens in terms of technology.

[0113] In some examples, as shown in FIGS. 3 and 5 , the radius of curvature of the second lens 410 is equal to 0.4 to 0.6 of the second dimension D2, and the ratio of the second dimension D2 to the maximum dimension of the second lens 410 in the direction perpendicular to the light-transmitting substrate 200 is 2 to 7. For example, the ratio of the second dimension D2 to the maximum dimension of the second lens 410 in the direction perpendicular to the light-transmitting substrate 200 is 2.1 to 4. For example, the ratio of the second dimension D2 to the maximum dimension of the second lens 410 in the direction perpendicular to the light-transmitting substrate 200 is 2.5 to 3. For example, the ratio of the second dimension D2 to the maximum dimension of the second lens 410 in the direction perpendicular to the light-transmitting substrate 200 is 2.8 to 5. For example, the ratio of the second dimension D2 to the maximum dimension of the second lens 410 in the direction perpendicular to the light-transmitting substrate 200 is 4.5 to 6. For example, the second dimension D2 of the second lens 410 is twice the radius of curvature. For example, the second dimension D2 is twice the thickness of the second lens 410, which is conducive to reducing the focal length of the second lens. Similarly, with reference to the first lens, the setting of the numerical relationship between the radius of curvature, the aperture, and the thickness of the second lens provided by the present disclosure needs to comprehensively consider the process factors and the short-focus factors.

[0114] In some examples, as shown in FIG. 3 and FIG. 8 , the orthographic projection of each first lens 310 on the light-transmitting substrate 200 overlaps with the orthographic projection of at least two second lenses 410 on the light-transmitting substrate 200, and the first lenses 310, the light-transmitting substrate 200, and the at least two second lenses 410 with overlapping orthographic projections form an optical structure, and the distance between at least one light-emitting unit 110 and the focal plane of its corresponding optical structure is not greater than 50 microns. For example, the distance between each light-emitting unit 110 and the focal plane of its corresponding optical structure is not greater than 50 microns. For example, the distance between at least one light-emitting unit 110 and the focal plane of its corresponding optical structure is not greater than 45 microns. For example, the distance between at least one light-emitting unit 110 and the focal plane of its corresponding optical structure is not greater than 40 microns. For example, the distance between at least one light-emitting unit 110 and the focal plane of its corresponding optical structure is not greater than 35 microns. For example, the distance between at least one light-emitting unit 110 and the focal plane of its corresponding optical structure is not greater than 30 microns. For example, the distance between at least one light-emitting unit 110 and the focal plane of its corresponding optical structure is not greater than 25 microns. For example, the distance between at least one light emitting unit 110 and the focal plane of its corresponding optical structure is not greater than 20 microns. For example, the distance between at least one light emitting unit 110 and the focal plane of its corresponding optical structure is not greater than 15 microns. For example, the distance between at least one light emitting unit 110 and the focal plane of its corresponding optical structure is not greater than 10 microns. For example, the distance between at least one light emitting unit 110 and the focal plane of its corresponding optical structure is not greater than 5 microns. For example, the light emitting unit may be located on the focal plane of its corresponding optical structure.

[0115] Figure 10 is a graph showing the effect of the air gap between the second lens and the light source on the convergence angle and uniformity of the backlight source. Figure 11 is a graph showing the effect of the air gap between the second lens and the light source on the light efficiency of the backlight source.

[0116] For example, as shown in Figures 10 and 11, line L11 represents the relationship curve between the air gap and the convergence angle of the backlight source, line L12 represents the relationship curve between the air gap and the uniformity of the backlight source, and position F is the focus of the optical structure composed of the first lens, the transparent substrate and the second lens.

[0117] For example, as shown in Figures 10 and 11, taking the refractive index of the first lens as 1.7, the refractive index of the transparent substrate as 1.5, the refractive index of the second lens as 1.6, the maximum size of the light-emitting unit as 268 microns, and the ratio of the aperture of the first lens to the center thickness as 2 as an example, the influence of the air gap on the convergence angle, uniformity and light efficiency of the backlight source as shown in Figures 10 and 11 is obtained. For example, the air gap may be no greater than 45 microns.

[0118] For example, as shown in Figures 10 and 11, when the air gap fluctuates within a range of 50 microns near the focal plane, the convergence angle of the backlight source remains basically unchanged, such as around 5 degrees, and the surface uniformity of the light emitted by the backlight source changes in a wave-like manner; the luminous efficiency of the backlight source is basically maintained at around 70%.

[0119] In some examples, as shown in FIG. 3 , the ratio of the thickness of the light-transmitting substrate 200 to the maximum dimension of the second lens 410 in a direction perpendicular to the light-transmitting substrate 200 is 8 to 20. For example, the maximum dimension of the second lens 410 in a direction perpendicular to the light-transmitting substrate 200 may be the center thickness or the arch height of the second lens 410. For example, the ratio of the thickness of the light-transmitting substrate 200 to the maximum dimension of the second lens 410 in a direction perpendicular to the light-transmitting substrate 200 is 10 to 15. For example, the ratio of the thickness of the light-transmitting substrate 200 to the maximum dimension of the second lens 410 in a direction perpendicular to the light-transmitting substrate 200 is 9 to 12. For example, the ratio of the thickness of the light-transmitting substrate 200 to the maximum dimension of the second lens 410 in a direction perpendicular to the light-transmitting substrate 200 is 11 to 16. For example, the ratio of the thickness of the light-transmitting substrate 200 to the maximum dimension of the second lens 410 in a direction perpendicular to the light-transmitting substrate 200 is 14 to 18.

[0120] In some examples, as shown in Fig. 3, the refractive index of the first lens 310 is greater than the refractive index of the transparent substrate 200. For example, the larger the refractive index of the first lens is, the thinner the transparent substrate can be, which is conducive to achieving a thin backlight source.

[0121] 3 , the refractive index of the second lens 410 is greater than the refractive index of the light-transmissive substrate 200. For example, the refractive index of the first lens 310 is greater than the refractive index of the second lens 410.

[0122] Figure 12 is a graph showing the effect of the thickness change of the light-transmitting substrate on the collimation angle and brightness uniformity of the backlight source when the second lens has different second sizes. Figure 13 is a graph showing the effect of the thickness change of the light-transmitting substrate on the light efficiency when the second lens has different second sizes. Figure 14 is a graph showing the effect of the thickness change of the light-transmitting substrate on the collimation angle and brightness uniformity of the backlight source when the second lens has different second sizes. Figure 15 is a graph showing the effect of the thickness change of the light-transmitting substrate on the light efficiency when the second lens has different second sizes. The third size of the light-emitting units corresponding to the graphs shown in Figures 12 and 13 is the same, the third size of the light-emitting units corresponding to the graphs shown in Figures 14 and 15 is the same, and Figures 12 and 13 correspond to different third sizes of the light-emitting units, respectively.

[0123] For example, as shown in Figures 12 and 13, taking the light-emitting unit as shown in Figure 4A, and the diagonal length of the light-emitting unit is 268 microns, the refractive index of the first lens is 1.7, the refractive index of the transparent substrate is 1.5, the refractive index of the second lens is 1.6, the radius of curvature of the first lens is 693 microns, the ratio of the aperture to the arch height of the first lens is 2, the aperture of the first lens is 1.13 to 1.21 mm, and the pitch of the light-emitting unit is 1.13 to 1.21 mm. As an example, referring to the above-mentioned relationship (1)-(11), or relationship (1')-(13'), the range of D2 value can be calculated. L21 represents the collimation curve when the aperture of the second lens is 85 microns, L22 represents the brightness uniformity curve when the aperture of the second lens is 85 microns, L31 represents the collimation curve when the aperture of the second lens is 100 microns, L32 represents the brightness uniformity curve when the aperture of the second lens is 100 microns, L41 represents the light efficiency curve when the aperture of the second lens is 85 microns, and L51 represents the light efficiency curve when the aperture of the second lens is 100 microns. For example, when the aperture of the second lens is 85 and 100 microns, when the thickness of the transparent substrate is greater than 600 microns, the convergence angle of the backlight source is less than 5°, and the light efficiency is about 70%, but the brightness uniformity of the backlight source gradually decreases when the thickness of the transparent substrate is greater than 650 microns. Therefore, when the aperture of the second lens is 85 microns and 100 microns, when the thickness of the transparent substrate is 650 microns, it can simultaneously meet the effects of a collimation angle of less than 5°, a light efficiency of about 70%, and a brightness uniformity greater than 80%.

[0124] For example, as shown in Figures 14 and 15, taking the light-emitting unit as shown in Figure 4B or 4C, and the diagonal length of the light-emitting unit is 500 microns, the refractive index of the first lens is 1.7, the refractive index of the transparent substrate is 1.5, the refractive index of the second lens is 1.6, the radius of curvature of the first lens is 1270 microns, the ratio of the aperture to the arch height of the first lens is 2, the aperture of the first lens is 1.8 to 3 mm, and the pitch of the light-emitting unit is 2.16 to 3 mm. As an example, referring to the above-mentioned relationship (1)-(11), or relationship (1')-(13'), the range of D2 value can be calculated. L61 represents the collimation curve when the aperture of the second lens is 120 microns, L62 represents the brightness uniformity curve when the aperture of the second lens is 120 microns, L71 represents the collimation curve when the aperture of the second lens is 140 microns, L72 represents the brightness uniformity curve when the aperture of the second lens is 140 microns, L81 represents the light efficiency curve when the aperture of the second lens is 120 microns, and L91 represents the light efficiency curve when the aperture of the second lens is 140 microns. For example, when the aperture of the second lens is 120 microns and 140 microns, when the thickness of the transparent substrate is greater than 1150 microns, the convergence angle of the backlight source is less than 5°, and the light efficiency is about 70% to 75%, but the brightness uniformity of the backlight source gradually decreases when the thickness of the transparent substrate is greater than 1150 microns. Therefore, when the aperture of the second lens is 140 microns and the thickness of the transparent substrate is 1150 microns, the collimation angle can be less than 5°, the light efficiency is about 70% to 75%, and the brightness uniformity is greater than 80%.

[0125] For example, as shown in FIG3 , when the diagonal length of the light emitting unit 110 is 268 μm, the maximum thickness of the second lens 410 is 0.05 mm, the thickness of the light-transmitting substrate 200 is 0.65 mm, the thickness of the first lens 310 is 0.46 to 0.63 mm, and the overall thickness of the backlight source is 1.68 to 1.82 mm.

[0126] For example, as shown in FIG3 , when the diagonal length of the light emitting unit 110 is 120 μm, the maximum thickness of the second lens 410 is 0.02 mm, the thickness of the light-transmitting substrate 200 is 0.2 mm, the thickness of the first lens 310 is 0.15 to 0.2 mm, and the overall thickness of the backlight source is 0.95 to 1.05 mm.

[0127] FIG16 is a brightness distribution diagram when only the first lens is provided in the backlight source shown in FIG7. The diagram in the upper left corner of FIG16 shows the brightness distribution diagram on the light exit surface of the backlight source, and the diagram in the lower left corner shows the brightness curve diagram when Y=0; the diagram on the right shows the brightness curve diagram when X=0. The two curve diagrams show the brightness fluctuation on the entire light exit surface.

[0128] For example, as shown in Figures 16 and 7, when there is a gap between adjacent first lenses, the light emitted from the gap between the first lenses is not refracted by the first lenses, and the gap will reduce the surface uniformity of the backlight. For example, when the projection of the first lens is a circle, even if the adjacent circles are closely arranged, there will still be a gap when the circles are tangent, and this gap will cause the surface uniformity of the backlight to decrease.

[0129] Fig. 17A is an orthographic projection relationship diagram of a portion of the first lens, a portion of the second lens, and a portion of the light emitting unit in an example of the backlight source shown in Fig. 3. Fig. 18 is a brightness distribution diagram of the backlight source shown in Fig. 17A.

[0130] In some examples, as shown in FIG. 17A , a plurality of first lenses 310 are closely arranged, and a plurality of second lenses 410 are closely arranged, which is beneficial to improving the surface uniformity of the backlight source.

[0131] In some examples, as shown in FIG. 17A , the shape of the orthographic projection of each first lens 310 on the light-transmitting substrate includes a circle, and the gap between the orthographic projections of any adjacent first lenses 310 on the light-transmitting substrate overlaps with the orthographic projection of at least one second lens 410 on the light-transmitting substrate. For example, the gap between the orthographic projections of adjacent first lenses 310 on the light-transmitting substrate overlaps with the orthographic projections of the plurality of second lenses 410 on the light-transmitting substrate. For example, the orthographic projection of at least one second lens 410 on the light-transmitting substrate is completely located within the gap. For example, the plurality of second lenses 410 include three types of second lenses 410, and the positional relationships of the three types of second lenses 410 with the first lens 310 are different, such as the orthographic projection of the first type of second lens 410 is completely located in the orthographic projection of the first lens 310, the orthographic projection of the second type of second lens 410 overlaps with the orthographic projection of the edge of the first lens 310, and the orthographic projection of the third type of second lens 410 does not overlap with the orthographic projection of the first lens 310 at all. For example, adjacent first lenses 310 may refer to three first lenses 310 whose orthographic projections are connected at the edges.

[0132] By using the second lens to fill the gaps between the first lenses, the light passing through the gaps between adjacent first lenses will be deflected by the second lens, such as deflected toward the collimating direction, which is beneficial to improving the surface uniformity of the light emitted by the backlight source.

[0133] For example, as shown in FIG. 18 , compared with the graph shown in FIG. 16 , the brightness fluctuation of the brightness curve of the backlight source at X=0 and Y=0 is smaller, and the surface uniformity of the backlight source is improved.

[0134] In some examples, as shown in FIG17A , the geometric center of the gap falls within the orthographic projection of the second lens 410 on the light-transmitting substrate, which is beneficial to further improve the surface uniformity of the backlight source. For example, the geometric center of the gap is located within the orthographic projection of a second lens 410 on the light-transmitting substrate, and the second lens 410 is completely located in the gap. For example, the optical axis of the second lens 410 passes through the geometric center of the gap overlapping with the second lens 410.

[0135] Fig. 17B is an orthographic projection relationship diagram of part of the first lens, part of the second lens, and part of the light-emitting unit in another example of the backlight source shown in Fig. 3. In the example shown in Fig. 17B and the example shown in Fig. 17A, the aperture of the first lens is the same, and the aperture of the second lens is different, and the aperture of the second lens shown in Fig. 17B is larger than the aperture of the second lens shown in Fig. 17A.

[0136] In some examples, as shown in FIG17B , the shape of the orthographic projection of each first lens 310 on the light-transmitting substrate includes a circle, the gap between the orthographic projections of any adjacent first lenses 310 on the light-transmitting substrate overlaps with the orthographic projection of at least one second lens 410 on the light-transmitting substrate, the geometric center of the gap falls within the orthographic projection of one second lens 410 on the light-transmitting substrate, and the orthographic projection of the one second lens 410 on the light-transmitting substrate overlaps with the orthographic projection of the first lens 310 on the light-transmitting substrate. FIG17B only illustrates one second lens whose orthographic projection overlaps with the gap, and omits other second lenses.

[0137] For example, as shown in FIG17B , three adjacent first lenses 310 are tangent to each other, and the orthographic projection of the one second lens 410 may overlap with the orthographic projection of at least one of the three first lenses 310. For example, the orthographic projection of the one second lens 410 may overlap with the orthographic projections of the three first lenses 310, but is not limited thereto, and the orthographic projection of the one second lens may also overlap with the orthographic projections of one first lens or two first lenses.

[0138] Fig. 17C is an orthographic projection relationship diagram of part of the first lens, part of the second lens, and part of the light-emitting unit in another example of the backlight source shown in Fig. 3. In the example shown in Fig. 17C and the examples shown in Fig. 17A and Fig. 17B, the aperture of the first lens is the same, and the aperture of the second lens is different. The aperture of the second lens shown in Fig. 17C is larger than the aperture of the second lens shown in Fig. 17A, and smaller than the aperture of the second lens shown in Fig. 17B.

[0139] In some examples, as shown in FIG17C , the shape of the orthographic projection of each first lens 310 on the light-transmitting substrate includes a circle, the gap between the orthographic projections of any adjacent first lenses 310 on the light-transmitting substrate overlaps with the orthographic projection of at least one second lens 410 on the light-transmitting substrate, the geometric center of the gap falls within the orthographic projection of one second lens 410 on the light-transmitting substrate, and the orthographic projection of the one second lens 410 on the light-transmitting substrate is tangent to the orthographic projection of the first lens 310 on the light-transmitting substrate. FIG17C only illustrates a second lens whose orthographic projection is tangent to the orthographic projection of the first lens, and omits other second lenses.

[0140] For example, as shown in FIG17C , three adjacent first lenses 310 are tangent to each other, and the orthographic projection of the one second lens 410 may be tangent to the orthographic projection of at least one of the three first lenses 310. For example, the orthographic projection of the one second lens 410 may be tangent to the orthographic projections of the three first lenses 310, but is not limited thereto, and the orthographic projection of the one second lens may also be tangent to the orthographic projections of one first lens or two first lenses.

[0141] Fig. 19 is an orthographic projection relationship diagram of a part of the first lens, a part of the second lens and a part of the light emitting unit in another example of the backlight source shown in Fig. 3. Fig. 20 is a brightness distribution diagram of the backlight source shown in Fig. 19.

[0142] In some examples, as shown in FIG19 , the shape of the orthographic projection of each first lens 310 on the light-transmitting substrate includes a hexagon, there is substantially no gap between the orthographic projections of adjacent first lenses 310 on the light-transmitting substrate, and the orthographic projection of at least one second lens 410 on the light-transmitting substrate overlaps the outline of the orthographic projections of at least two first lenses 310 on the light-transmitting substrate. For example, the adjacent edges of adjacent first lenses 310 whose orthographic projections are hexagons are in contact to achieve a close arrangement with multiple second lenses with smaller apertures, which can break the focusing effect of the first lens on light, so as to achieve short focus while improving the light extraction efficiency and the light extraction uniformity of the same first lens, thereby improving the uniformity of the surface light source of the backlight source.

[0143] For example, as shown in FIG. 20 , relative to the graph shown in FIG. 18 , the brightness fluctuation of the brightness curve of the backlight source at X=0 and Y=0 is smaller, and the surface uniformity of the backlight source can be further improved by further reducing the gap between the first lenses.

[0144] For example, as shown in FIG. 17A and FIG. 19 , the shape of the orthographic projection of the second lens 410 on the light-transmitting substrate may be a circle, but is not limited thereto, and may also be a polygon such as a hexagon or an octagon.

[0145] For example, as shown in Figures 17A and 19, a plurality of second lenses 410 may be arranged in an array along the X direction and the Z direction. However, the invention is not limited thereto, for example, two adjacent rows of second lenses arranged along the Z direction may be staggered, which is beneficial to further reduce the gap between adjacent second lenses.

[0146] FIG21 is a graph showing the relationship between the convergence angle and the brightness of the backlight source shown in FIG3. For example, as shown in FIG21, K1 and K2 respectively represent the relationship between the brightness of the backlight source emitting light in two different directions and the convergence angle. The two different directions may be the X direction and the Z direction shown in FIG4A, respectively, and the spectrum graphs of the two different directions substantially overlap. For example, the brightness of the light emitted by the backlight source in two different directions is about 150,000 nits at ±5 degrees, and the maximum brightness of the backlight source is close to 1,000,000 nits. For example, each backlight source has a peak value. For example, by setting the light source in the backlight source near the focal plane of the optical structure, it is possible to avoid the backlight source emitting a multi-peak spectrum, which is conducive to achieving the effect of an ultra-high collimation surface light source.

[0147] Fig. 22 is a partial structural diagram of a display device provided according to another embodiment of the present disclosure. As shown in Fig. 22, the display device includes a backlight source 20 in any of the above examples and a display panel 10 located at the light emitting side of the backlight source 20.

[0148] In some examples, as shown in FIG22 , the display panel 10 includes a plurality of sub-pixels 11, the maximum size of each sub-pixel parallel to the light-transmitting substrate 200 is a fourth size, and the distance between adjacent first lenses 310 is less than the fourth size. By setting the distance between adjacent first lenses to be less than the size of the sub-pixel, it is helpful to reduce the influence of the gap between the first lenses in the backlight source on the uniformity of light output and the influence on the display screen of the display panel.

[0149] For example, as shown in FIG. 22 , the display panel 10 may be a liquid crystal display panel, including an array substrate and an opposing substrate disposed opposite to each other, and a liquid crystal layer located between the array substrate and the opposing substrate. For example, the sub-pixel 11 may include a pixel electrode and a common electrode. The maximum size of the above-mentioned sub-pixel in a direction parallel to the light-transmitting substrate may be the maximum size of the light-emitting area of ​​the sub-pixel, such as the light-emitting area may be an area defined by a black matrix disposed on the opposing substrate, and the light-emitting area is parallel to the light-emitting surface of the backlight source.

[0150] There are a few points to note:

[0151] (1) In the drawings of the embodiments of the present disclosure, only the structures related to the embodiments of the present disclosure are involved, and other structures can refer to the general design.

[0152] (2) In the absence of conflict, features in the same embodiment or in different embodiments of the present disclosure may be combined with each other.

[0153] The above description is merely an exemplary embodiment of the present disclosure and is not intended to limit the protection scope of the present disclosure. The protection scope of the present disclosure is determined by the appended claims.

Claims

A backlight source, comprising: A light source, comprising a plurality of light-emitting units; A light-transmitting substrate, located on the light-emitting side of the light source; A first lens group is located at the light exiting side of the light-transmitting substrate, and the first lens group includes a plurality of first lenses; a second lens group is located at the light incident side of the light-transmitting substrate, and the second lens group includes a plurality of second lenses, wherein the maximum size of each first lens in a direction parallel to the light-transmitting substrate is a first size, the maximum size of each second lens in a direction parallel to the light-transmitting substrate is a second size, the first size is greater than the second size, and the orthographic projection of at least one second lens on the light-transmitting substrate overlaps with the contour of the orthographic projection of at least one first lens on the light-transmitting substrate or is located in the interval between the orthographic projections of adjacent first lenses on the light-transmitting substrate; the maximum size of each light-emitting unit in a direction parallel to the light-transmitting substrate is a third size, the ratio of the second size to the third size is 0.2-0.5, and the ratio of the second size to the first size is 0.04-0.

2. The backlight source according to claim 1, wherein: The ratio of the first size to the pitch between adjacent light emitting units is 0.7 to 1.

3. The backlight source according to claim 1 or 2, wherein: A distance between an optical axis of at least one first lens and an optical axis of the second lens closest to the optical axis of the at least one first lens is less than 15 micrometers. The backlight source according to any one of claims 1 to 3, wherein: The multiple first lenses are arranged in one-to-one correspondence with the multiple light-emitting units, and the orthographic projection of each first lens on the light-transmitting substrate overlaps with the orthographic projection of at least two second lenses on the light-transmitting substrate, the first lenses with overlapping orthographic projections, the light-transmitting substrate and the at least two second lenses form an optical structure, and the distance between at least one light-emitting unit and the focal plane of the optical structure corresponding to it is not greater than 50 microns. The backlight source according to any one of claims 1 to 4, wherein: The plurality of first lenses are closely arranged, and the plurality of second lenses are closely arranged. The backlight source according to claim 5, wherein: The shape of the orthographic projection of each first lens on the transparent substrate includes a hexagon, there is basically no gap between the orthographic projections of adjacent first lenses on the transparent substrate, and the orthographic projection of at least one second lens on the transparent substrate overlaps the outline of the orthographic projections of at least two first lenses on the transparent substrate. The backlight source according to claim 5, wherein: The shape of the orthographic projection of each first lens on the light-transmitting substrate includes a circle, and the gap between the orthographic projections of any adjacent first lenses on the light-transmitting substrate overlaps with the orthographic projection of at least one second lens on the light-transmitting substrate. The backlight source according to claim 5, wherein: The orthographic projection of each first lens on the transparent substrate has a circular shape, a gap is provided between the orthographic projections of any adjacent first lenses on the transparent substrate, and the orthographic projection of at least one second lens on the transparent substrate is completely located in the gap. The backlight source according to claim 7 or 8, wherein: The geometric center of the gap falls within the orthographic projection of a second lens on the light-transmitting substrate, and the orthographic projection of the second lens on the light-transmitting substrate is completely located in the gap. The backlight source according to claim 7, wherein: The geometric center of the gap falls within the orthographic projection of a second lens on the light-transmitting substrate, and the orthographic projection of the second lens on the light-transmitting substrate overlaps or is tangent to the orthographic projection of the first lens on the light-transmitting substrate. The backlight source according to any one of claims 1 to 10, wherein: Each light emitting unit is configured to emit white light. The backlight source according to claim 11, wherein: At least one light emitting unit includes sub-light emitting units of different colors. The backlight source according to any one of claims 1 to 12, wherein: The ratio of the thickness of the light-transmitting substrate to the maximum dimension of the second lens in a direction perpendicular to the light-transmitting substrate is 8-20. The backlight source according to any one of claims 1 to 13, wherein: The first lens includes a plano-convex lens, the second lens includes a plano-convex lens, and the plane of the first lens and the plane of the second lens are both facing the light-transmitting substrate. The backlight source according to claim 14, wherein: The first lens and the second lens each include a spherical lens. The backlight source according to claim 15, wherein: A ratio of a radius of curvature of the first lens to the first size is 0.4 to 0.6, and a ratio of the first size to a maximum size of the first lens in a direction perpendicular to the light-transmitting substrate is 1.5 to 6. The backlight source according to claim 15, wherein: The ratio of the radius of curvature of the second lens to the second size is 0.4-0.6, and the ratio of the second size to the maximum size of the second lens in a direction perpendicular to the light-transmitting substrate is 2-7. The backlight source according to claim 13, wherein: The refractive index of the first lens is greater than the refractive index of the light-transmitting substrate. The backlight source according to any one of claims 1 to 18, wherein: The refractive index of the second lens is greater than the refractive index of the light-transmitting substrate. The backlight source according to any one of claims 1 to 19, wherein: The angle of the light emitted by the backlight source is ±α degrees, and α is not greater than 5. A display device comprises a display panel and the backlight source according to any one of claims 1 to 20, wherein the display panel is located on the light emitting side of the backlight source. The display device according to claim 21, wherein The display panel includes a plurality of sub-pixels, the maximum size of each sub-pixel in a direction parallel to the light-transmitting substrate is a fourth size, and the distance between adjacent first lenses is smaller than the fourth size.

Images