Display backlight module and head-up display

Abstract

The display backlight module comprises a light source assembly, a lens assembly and a diffusion film, a first lens and a second lens of the lens assembly are sequentially arranged at intervals in the irradiation direction of the light source assembly, the first lens is used for converting scattered light rays emitted by the light source assembly into parallel light rays, and the second lens is used for converting the parallel light rays into parallel light rays. The side, facing the first lens, of the second lens is concaved inwards to form a diverging curved surface used for diverging parallel light rays, the light rays emitted by the source assembly are scattered light rays, the scattered light rays are converted into collimated and even parallel light rays after passing through the condensing curved surface, and the light rays are diffused twice through the second lens and the diffusion film. On the premise that the imaging range of the display screen is met, the diffusion angle of the diffusion film can be reduced, and the lighting effect brightness and the brightness uniformity can be improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of displays, and in particular relates to a display backlight module and a head-up display. Background Art

[0002] Head-up display, also known as head-up display, is used in the automotive field to display important driving information such as speed, navigation, steering, fuel consumption, etc. It allows car drivers to focus on driving without having to look down at the dashboard, thus ensuring safe driving and improving the driving experience.

[0003] In the prior art, the backlight module of a head-up display (HUD) consists of a light source, a lens, and a diffuser film, which are arranged in sequence. The lens converges the light from the light source into uniformly collimated parallel rays, while the diffuser film diffuses the parallel rays into multi-angle rays, increasing the light radiation area and making the virtual image displayed by the HUD visible from multiple angles. To ensure the light radiation area, the diffuser film must have a large diffusion angle. However, as the diffusion angle increases, the luminous efficiency of the light passing through the diffuser film decreases, affecting the imaging quality of the HUD. Utility Model Content

[0004] In view of the above-mentioned defects or deficiencies, the present invention provides a display backlight module and a head-up display, aiming to solve the technical problem of poor light efficiency and brightness of existing head-up displays.

[0005] To achieve the above-mentioned purpose, the present invention provides a display backlight module, wherein the display backlight module includes a light source assembly, a lens assembly and a diffusion film, the first lens and the second lens of the lens assembly are arranged in sequence along the irradiation direction of the light source assembly, the first lens is used to convert the scattered light emitted by the light source assembly into parallel light, and the second lens is concave on the side facing the first lens to form a diverging surface for diverging the parallel light.

[0006] In an embodiment of the present invention, the diverging curved surface has a first curvature radius and a second curvature radius in a one-to-one correspondence in the length direction and the width direction of the second lens, respectively, and the first curvature radius is smaller than the second curvature radius.

[0007] In an embodiment of the present invention, the light source assembly includes a light emitting element and a grating. The grating is arranged between the light emitting element and the first lens and forms a light path for light to pass through. The light path is gradually expanded from the light emitting element toward the first lens.

[0008] In an embodiment of the present invention, there are multiple light-emitting elements, which are arranged in a rectangular array. The grating forms multiple light path channels, and the multiple light path channels are arranged in a one-to-one correspondence with the multiple light-emitting elements.

[0009] In an embodiment of the present invention, a side of the first lens facing away from the grating is raised to form a plurality of light-converging curved surfaces, and the plurality of light-converging curved surfaces are arranged in a one-to-one correspondence with the plurality of light path channels.

[0010] In the embodiment of the present invention, the optical path channel is in a prism shape.

[0011] In an embodiment of the present invention, the side of the second lens facing the diffusion film is a light emitting plane, and the area of ​​the light emitting plane is equal to the projected area of ​​the diverging curved surface in the irradiation direction.

[0012] In an embodiment of the present invention, the diffusion film has a first diffusion angle in the length direction and a second diffusion angle in the width direction, and the first diffusion angle is greater than the second diffusion angle.

[0013] In an embodiment of the present invention, the edge of the diffusion film is disposed beyond the second lens.

[0014] In order to achieve the above-mentioned object, the present invention further provides a head-up display, wherein the head-up display includes the above-mentioned display backlight module.

[0015] Through the above technical solution, the display backlight module provided by the embodiment of the utility model has the following beneficial effects:

[0016] When using the above-mentioned display backlight module, it includes a light source assembly, a lens assembly and a diffusion film that are arranged in sequence at intervals. The light emitted by the light source assembly is scattered light with an angle between ±90°. The first lens in the lens assembly forms a focusing surface. The scattered light is converted into collimated and uniform parallel light after passing through the focusing surface. The second lens in the lens assembly forms a diverging surface. After passing through the diverging surface, the parallel light is deflected outward toward the center point of the diverging surface, so that the light is irradiated on the diffusion film at an oblique angle and finally diffused by the diffusion film to the display screen. That is, the light passes through the diffusion effect of the second lens and the diffusion film twice. On the premise of meeting the imaging range of the display screen, the diffusion angle of the diffusion film can be reduced, and the light efficiency brightness and brightness uniformity can be increased.

[0017] Other features and advantages of the present invention will be described in detail in the subsequent detailed description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide an understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0019] Figure 1 is a schematic diagram of a display backlight module according to an embodiment of the present invention;

[0020] Figure 2is a top view of a light source assembly according to an embodiment of the present utility model;

[0021] Figure 3 is a bottom schematic diagram of a light box according to an embodiment of the present utility model;

[0022] Figure 4 is a cross-sectional view of a light box according to an embodiment of the present utility model;

[0023] Figure 5 is a schematic diagram of illumination by a light source assembly according to an embodiment of the present utility model;

[0024] Figure 6 1 is a schematic diagram of light divergence of the second lens in the longitudinal direction according to one embodiment of the present invention;

[0025] Figure 7 Schematic diagram of light divergence of the second lens in the width direction according to one embodiment of the present invention.

[0026] Description of Reference Numerals

[0027] 1 light source assembly 11 light emitting element

[0028] 12 gratings and 13 optical channels

[0029] 2 Lens assembly 21 first lens

[0030] 211 focusing curved surface 22 second lens

[0031] 221 diverging surface 222 light emitting plane

[0032] 3 diffusion films 4 light boxes

[0033] 41 guide portion 42 positioning portion

[0034] 43 stop surface DETAILED DESCRIPTION

[0035] The following is a detailed description of the specific embodiments of the present invention in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and the divergent surface 221, and are not intended to limit the present invention.

[0036] The display backlight module and the head-up display of the present invention are described below with reference to the accompanying drawings.

[0037] like Figure 1 As shown, the utility model provides a display backlight module, wherein the display backlight module includes:

[0038] Light source component 1;

[0039] The lens assembly 2 includes a first lens 21 and a second lens 22 spaced apart from each other along the illumination direction of the light source assembly 1. The first lens 21 is configured to convert scattered light emitted by the light source assembly 1 into parallel light. The second lens 22 is concave on a side facing the first lens 21 to form a diverging curved surface 221. The diverging curved surface 221 is configured to diverge the parallel light.

[0040] The diffusion film 3 is disposed on a side of the second lens 22 facing away from the first lens 21 .

[0041] When using the above-mentioned display backlight module, it includes a light source assembly 1, a lens assembly 2 and a diffusion film 3 arranged in sequence, and the light emitted by the light source assembly 1 is scattered light, and its angle is between ±90°. The first lens 21 in the lens assembly 2 is formed with a focusing surface 211. After passing through the focusing surface 211, the scattered light is converted into collimated and uniform parallel light. The second lens 22 in the lens assembly 2 is formed with a diverging surface 221. After passing through the diverging surface 221, the parallel light is deflected outward toward the center point of the diverging surface 221, so that the light is irradiated on the diffusion film 3 at an oblique angle and finally diffused by the diffusion film 3 to the display screen. That is, the light passes through the diffusion effect of the second lens 22 and the diffusion film 3 twice. On the premise of meeting the imaging range of the display screen, the diffusion angle of the diffusion film 3 can be reduced, and the light efficiency brightness and brightness uniformity can be increased.

[0042] In the embodiment of the present invention, the diverging curved surface 221 has a first curvature radius and a second curvature radius in a one-to-one correspondence in the length direction and the width direction of the second lens 22. Figure 6 and Figure 7 After passing through the diverging curved surface 221, parallel light rays are deflected by a certain angle in both the length and width directions of the second lens 22. The deflection angle is negatively correlated with the radius of curvature; the larger the radius of curvature, the smaller the deflection angle of the parallel light rays. Therefore, the first and second radii of curvature are selected based on the aspect ratio of the display screen. Specifically, if the display screen is arranged horizontally, the first radius of curvature is smaller than the second radius of curvature, and the deflection angle of the parallel light rays in the length direction of the second lens 22 is greater than the deflection angle in the width direction of the second lens 22. This ensures sufficient light efficiency and brightness at both ends of the display screen, improving image quality.

[0043] In the embodiment of the present invention, the second lens 22 is configured as a bridge-type structure, that is, the side of the second lens 22 facing the first lens 21 is a diverging curved surface 221, and the side of the second lens 22 facing the diffusion film 3 is a light-emitting plane 222. The area of ​​the light-emitting plane 222 is equal to the projected area of ​​the diverging curved surface 221 in the illumination direction, and the connecting surface between the diverging curved surface 221 and the light-emitting plane 222 is a plane, so that the projection of the diverging curved surface 221 on the light-emitting plane 222 completely overlaps with the light-emitting plane 222. Through the above-mentioned bridge-type structure, parallel light rays from the four side edges of the diverging curved surface 221 are scattered, thereby reducing stray light reaching the human eye.

[0044] Of course, the present invention is not limited to this. The first lens 21 can also be a lens with any surface type among quadratic surface, spherical surface, aspherical surface, and free-form surface; the second lens 22 can also be a lens with any surface type among quadratic surface, spherical surface, aspherical surface, and free-form surface.

[0045] like Figure 2 and Figure 5 As shown, in an embodiment of the present invention, the light source assembly 1 includes a light emitting element 11 and a grating 12. The grating 12 is disposed between the light emitting element 11 and the first lens 21 and forms an optical path 13 for light to pass through. The optical path 13 is arranged to gradually expand from the light emitting element 11 toward the first lens 21. The sidewalls of the optical path 13 are made of a high-reflectivity material. The scattered light emitted by the light emitting element 11 is initially converged by the grating 12, so that the angle range of the scattered light is concentrated from ±90° to ±70°. On the one hand, the efficiency of light energy utilization is improved, and the brightness of the light emitted by the light source assembly 1 on the diffusion film 3 is guaranteed without increasing the power consumption of the light emitting element 11. The lower the power consumption of the light emitting element 11, the lower its heat generation, which can avoid adverse effects on the TFT display screen of the head-up display. On the other hand, the first lens 21 only needs to process the scattered light within the ±70° range. This can reduce the thickness of the first lens 21 and the distance between the first lens 21 and the light emitting element 11, thereby reducing the overall thickness of the display backlight module and facilitating flexible placement on the vehicle. Specifically, the optical path channel 13 can be configured to be in a prism shape or a truncated cone shape.

[0046] In an embodiment of the present invention, there are multiple light-emitting elements 11, and the multiple light-emitting elements 11 are arranged in a rectangular array. The grating 12 forms a plurality of light path channels 13, and the multiple light path channels 13 are arranged in a one-to-one correspondence with the multiple light-emitting elements 11, so that the grating 12 has a better light-gathering effect. At the same time, the first lens 21 is raised on the side away from the grating 12 to form a plurality of focusing surfaces 211, and the multiple focusing surfaces 211 are arranged in a one-to-one correspondence with the multiple light path channels 13. The light paths of each light-emitting element 11 are independent of each other, so that the divergence angle of the light after passing through the first lens 21 is small, so that the light enters the second lens 22 vertically to the maximum extent and the light intensity at each position point on the second lens 22 is equal, ensuring brightness uniformity.

[0047] Specifically, the light emitting element 11 is preferably a Lambertian light source LED lamp, and the light emitting angle of the light emitting element 11 is ±90°. Its light intensity distribution can be expressed by the following formula:

[0048] I=I0×cosθ;

[0049] Where I0 is the intensity of the light when it is perpendicular to the surface of the light source, θ is the angle between the light and the normal of the light source surface, and I is the intensity of the light when the angle is θ.

[0050] In an embodiment of the present invention, the diffusion film 3 has a first diffusion angle in the length direction and a second diffusion angle in the width direction. The light is deflected again at a certain angle on the diffusion film 3. Unlike the light that is deflected in a single direction when passing through the second lens 22, the light is deflected in different directions when passing through the diffusion film 3. With the length direction as a reference, the angle formed by the light exiting the diffusion film 3 is the first diffusion angle, and with the width direction as a reference, the angle formed by the light exiting the diffusion film 3 is the second diffusion angle. Specifically, if the display screen is arranged horizontally, the first diffusion angle is greater than the second diffusion angle, and sufficient light efficiency and brightness are still guaranteed at both ends of the display screen, thereby improving the imaging quality.

[0051] In the embodiment of the present invention, the edge of the diffusion film 3 is arranged beyond the second lens 22 so that the light emitted from the outer edge of the second lens 22 can also pass through the diffusion film 3, further improving the light energy utilization efficiency.

[0052] In order to achieve the above objectives, the present invention further provides a head-up display, wherein the head-up display includes the above-mentioned display backlight module. Since the head-up display adopts all the technical solutions of the above-mentioned embodiments, it has at least the above-mentioned beneficial effects.

[0053] Specifically, see Figure 3 and Figure 4The head-up display also includes a light box 4 and a display screen. The upper end of the light box 4 is formed with an inclined support surface, and the display screen is arranged on the support surface. The diffusion film 3 is attached to the back panel of the display screen. The second lens 22, the first lens 21, the grating 12 and the light-emitting element 11 are arranged in the light box 4 from top to bottom.

[0054] Specifically, the lower end of the light box 4 is configured as an open structure, and the light source assembly 1 and lens assembly 2 are placed within the light box 4 through the lower opening. A stop surface 43 is formed on the inner wall of the light box 4. The upper end surface of the second lens 22 abuts the stop surface 43 to ensure the accuracy of the installation position of the second lens 22. The position of the stop surface 43 is determined by the set distance between the second lens 22 and the diffuser film 3. A stop structure is provided on the outer edge of the first lens 21. The upper and lower ends of the stop structure extend beyond the first lens 21 to abut against the second lens 22 and the grating 12, respectively, so that the grating 12, the first lens 21, and the second lens 22 are arranged in an interval within the light box 4.

[0055] In this embodiment of the present invention, a guide portion 41 extending in the height direction is formed on the inner sidewall of the light box 4. The outer edges of the first lens 21, the second lens 22, and the grating 12 are each formed with a guide notch corresponding to the guide portion 41. The second lens 22, the first lens 21, and the grating 12 are sequentially installed within the light box 4 along the guide portions 41. Specifically, there are three guide portions 41, formed on the rear, left, and right inner walls of the light box 4, respectively. The first lens 21, the second lens 22, and the grating 12 each have three guide notches corresponding to the three guide portions 41. During installation, the operator must align the guide notches with the guide portions 41 one by one to ensure accurate placement of the first lens 21, the second lens 22, and the grating 12 within the light box 4. Furthermore, a positioning portion 42 is formed on the outer sidewall at the lower end of the light box 4. A corresponding slot is provided at the head-up display installation location in the vehicle to facilitate quick positioning and installation of the head-up display.

[0056] Specifically, the head-up display further includes a thermal pad and a heat sink disposed at the lower end of the light box 4 . The thermal pad is respectively attached to the light emitting element 11 and the heat sink to transfer the heat of the light emitting element 11 to the heat sink for heat dissipation.

[0057] In a specific embodiment of the present invention, the display backlight module of the head-up display adopts the following configuration:

[0058] Light-emitting assembly: There are eight light-emitting elements 11, all of which are Lambertian LED lamps. The eight light-emitting elements 11 are arranged in two rows and four columns. Each light-emitting element 11 is correspondingly provided with a light path channel 13, and the side wall inclination angle of the light path channel 13 is 70°.

[0059] Lens assembly 2: The side of the first lens 21 facing the grating 12 is flat, and the side away from the grating 12 forms eight focusing surfaces 211. The surface shape of the focusing surface 211 is a quadratic surface with a curvature R = -0.142705 and a quadratic surface coefficient K = -1.4912. After passing through the first lens 21, the scattered light is converted into parallel light, and the divergence angle of the parallel light is less than 3°; the second lens 22 has a bridge-type structure.

[0060] Diffuser 3: Set to an asymmetric diffusion angle of 25°×12°.

[0061] When the head-up display uses the display backlight module configured as described above, the brightness reached by the human eye is 12647 nits, with a brightness uniformity greater than 80%, demonstrating excellent light efficiency and brightness uniformity. It should be noted that the specific values ​​of the above structural parameters are merely selected for a specific embodiment of the present invention and are not intended to limit the present invention. Depending on actual usage, other values ​​of the structural parameters may also be used.

[0062] In the description of this utility model, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this utility model, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0063] In this utility model, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. For those skilled in the art, the specific meanings of the above terms in this utility model can be understood according to specific circumstances.

[0064] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0065] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are illustrative and cannot be understood as limitations on the present invention. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A display backlight module, characterized in that: The display backlight module includes: Light source assembly (1); A lens assembly (2) comprising a first lens (21) and a second lens (22) arranged in sequence and spaced apart along the irradiation direction of the light source assembly (1), wherein the first lens (21) is used to convert scattered light emitted by the light source assembly (1) into parallel light, and the second lens (22) is concavely formed with a diverging curved surface (221) on a side facing the first lens (21), and the diverging curved surface (221) is used to diverge the parallel light; A diffusion film (3) is provided on a side of the second lens (22) facing away from the first lens (21).

2. The display backlight module according to claim 1, wherein: The diverging curved surface (221) has a first curvature radius and a second curvature radius in a one-to-one correspondence in the length direction and the width direction of the second lens (22), respectively, and the first curvature radius is smaller than the second curvature radius.

3. The display backlight module according to claim 1, wherein: The light source assembly (1) comprises a light emitting element (11) and a grating (12); the grating (12) is arranged between the light emitting element (11) and the first lens (21), and forms a light path (13) for light to pass through; the light path (13) is arranged in a gradually expanding manner from the light emitting element (11) toward the first lens (21).

4. The display backlight module according to claim 3, wherein: There are a plurality of light-emitting elements (11), and the plurality of light-emitting elements (11) are arranged in a rectangular array. The grating (12) forms a plurality of light path channels (13), and the plurality of light path channels (13) are arranged in a one-to-one correspondence with the plurality of light-emitting elements (11).

5. The display backlight module according to claim 4, characterized in that: A side of the first lens (21) facing away from the grating (12) is raised to form a plurality of light-gathering curved surfaces (211), and the plurality of light-gathering curved surfaces (211) are arranged in a one-to-one correspondence with the plurality of light path channels (13).

6. The display backlight module according to claim 3, wherein: The optical path channel (13) is in a prism shape.

7. The display backlight module according to any one of claims 1 to 6, characterized in that: The side of the second lens (22) facing the diffusion film (3) is a light-emitting plane (222), and the area of ​​the light-emitting plane (222) is equal to the projection area of ​​the diverging curved surface (221) in the irradiation direction.

8. The display backlight module according to any one of claims 1 to 6, characterized in that: The diffusion film (3) has a first diffusion angle in the length direction and a second diffusion angle in the width direction, and the first diffusion angle is greater than the second diffusion angle.

9. The display backlight module according to any one of claims 1 to 6, characterized in that: The edge of the diffusion film (3) is arranged beyond the second lens (22).

10. A head-up display, characterized in that: The head-up display comprises the display backlight module according to any one of claims 1 to 9.

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