TWI838802B - Backlight modules, picture generation units, head-up displays, and vehicles - Google Patents

Abstract

Embodiments of the present disclosure relate to the field of display technology. A backlight module, a picture generation unit, a head-up display, and a vehicle are provided. The backlight module includes a circuit board, a plurality of light-emitting elements, a plurality of reflectors, and a plurality of condenser lenses. Each of the plurality of reflectors covers at least two of the plurality of light-emitting elements. All the light-emitting elements covered by one of the plurality of reflectors are defined as a light source group, and a plurality of the light source groups are arranged in multiple rows and multiple columns. The on, off and luminous intensity of all the light emitting elements in anyone of the light source groups can be independently controlled as a whole. Each of the plurality of condenser lenses is aligned with a corresponding one of the plurality of the light source groups. The backlight module has high brightness and high uniformity.

Description

Backlight module, image generation unit, head-up display and vehicle

This application relates to the field of display technology, specifically, to a backlight module, an image generation unit, a head-up display, and a vehicle.

In a head-up display, an image generating unit is used to provide image light. Among them, the traditional image generating unit includes a backlight module and a liquid crystal display panel. In order to make the entire surface of the liquid crystal display panel illuminate without generating dark corners, the image generating unit mostly uses a direct-type backlight module for illumination. However, although the known direct-type backlight module can illuminate the entire surface, it can cause the problem of over-brightness. Moreover, the known backlight module is in a normal fully lit state, which causes the brightness value of the black screen to increase, resulting in a decrease in the contrast of the screen.

The first aspect of the present application provides a backlight module. The backlight module includes: a circuit board; a plurality of light-emitting elements, which are spaced apart on the circuit board, and each of the light-emitting elements is electrically connected to the circuit board; a plurality of reflectors, which are located on the circuit board, and each of the reflectors covers at least two of the light-emitting elements, and all of the light-emitting elements covered by each of the reflectors are defined as a light source group, and the plurality of light source groups are arranged in an array of a plurality of rows and a plurality of columns, and the opening, closing, and luminous brightness of all of the light-emitting elements in each of the light source groups can be independently controlled as a whole; and a plurality of focusing lenses, which are located on a side of the plurality of reflectors away from the plurality of light-emitting elements, and each of the focusing lenses is aligned with one of the light source groups.

In the backlight module, the reflector is used to correct the light-emitting angle of the light-emitting element and produce a focusing effect. The focusing lens is used to converge the light emitted by the corresponding light-emitting element to amplify the light-emitting brightness of the light-emitting element, thereby improving the light-emitting brightness of the backlight module. Moreover, in the backlight module, the opening, closing and light-emitting brightness of all the light-emitting elements in each light source group can be independently controlled as a whole, so that the brightness of different areas of the backlight module can be adjusted accordingly. In this way, the effect of regional dynamic display is achieved with better contrast. Moreover, compared with the known backlight module with full-surface light emission, the problem of pre-overbrightness can also be avoided.

The second aspect of the present application provides an image generation unit. The image generation unit includes: a liquid crystal display panel for forming image light; and a backlight module according to the first aspect, which is located on one side of the liquid crystal display panel and provides the liquid crystal display panel with the backlight required to form the image light.

The image generation unit includes the backlight module described in the first aspect, so it has at least the same advantages as the backlight module described in the first aspect, which will not be elaborated.

The third aspect of the present application provides a head-up display. The head-up display comprises: an image generating unit according to the second aspect; and a reflective component for reflecting the image light to a projection medium for imaging.

The head-up display includes the image generation unit described in the second aspect, so it has at least the same advantages as the image generation unit described in the second aspect, which will not be repeated.

The fourth aspect of the present application provides a vehicle. The vehicle comprises: a windshield; and the head-up display according to the third aspect, wherein the windshield is the projection medium.

The vehicle includes the head-up display described in the third aspect, so it has at least the same advantages as the head-up display described in the third aspect, which will not be elaborated.

100: Vehicles

110: Windshield

120: Heads-up display

10: Base

20: Image generation unit

21: Shell

211: Cover

212:Frame

221: First fastener

222: Second fastener

23: LCD panel

24: Diffusion element

25: Pad

26: Backlight module

261: Light board

2611: Circuit board

2612:Drive chip

2613: Connector

2614: Light-emitting element

262:Reflector

263: Focusing lens

30: Reflection component

31: First reflector

32: Second reflector

E: Eyes

H1: light outlet

H2: Opening

R: Accommodation cavity

MH1: First mounting hole

MH2: Second mounting hole

G: Light source group

dy: line spacing

dx: row spacing

X: First direction

Y: Second direction

L: Image light

S: Reflective surface

Sa: light incident surface

Sb: light-emitting surface

β: tilt angle

△X: distance

Figure 1 is a schematic diagram of the structure of a vehicle according to an embodiment of the present application.

FIG2A is a schematic diagram of the structure of the light panel, reflector and focusing lens of the image generation unit in FIG1 assembled together.

Figure 2B is a schematic cross-sectional view along line A-A of Figure 2A.

Figure 3 is a three-dimensional schematic diagram of the image generation unit in Figure 1.

Figure 4 is a three-dimensional exploded view of the image generation unit in Figure 3.

FIG5 is a plan view schematic diagram of the light panel in the image generation unit shown in FIG4.

FIG6 is a top view of the light panel and focusing lens in the image generation unit shown in FIG4.

FIG7 is a brightness diagram obtained by analogy when the light-emitting element of the image generation unit shown in FIG4 is fully lit.

FIG8 is an analog luminance diagram obtained when the 6 rows and 8 columns of light-emitting elements in the middle area of the image generation unit shown in FIG4 are lit.

FIG9 is a brightness diagram obtained by analogy when the 2 rows and 4 columns of light-emitting elements in the middle area of the image generation unit shown in FIG4 are lit.

FIG10 is a brightness diagram obtained by analogy when the image generation unit shown in FIG4 lights up the light-emitting elements in horizontally spaced rows.

FIG11 is a brightness diagram obtained by analogy when the image generation unit shown in FIG4 lights up the light-emitting elements in alternate lines in the vertical direction.

FIG12 is a brightness diagram obtained by analogy when the light-emitting elements at the two side edges and the center area of the image generation unit shown in FIG4 are lit.

FIG13 is a brightness diagram obtained by analogy when the light-emitting elements in the diagonal area of the image generation unit shown in FIG4 are lit.

FIG14 is a brightness diagram obtained by analogy when the light-emitting elements in the upper and lower edge regions of the image generation unit shown in FIG4 are lit.

FIG15 is a brightness diagram obtained by analogy when the half-area light-emitting element of the image generation unit shown in FIG4 is lit.

Head up display (HUD) technology, also known as head-up display technology, has been increasingly widely used in the automotive, aerospace and marine fields in recent years. For example, it can be applied to vehicles, as well as other transportation vehicles such as airplanes, aerospace aircraft, and ships. For ease of description, in this application, the vehicle-mounted HUD is used as an example for description. However, it should be understood that this cannot be used as a limitation on this application.

Specifically, the head-up display uses the principle of optical reflection to project important driving-related information (such as driving speed, battery voltage, water tank temperature, engine speed, vehicle fuel consumption, navigation route, etc.) onto the windshield and reflects it into the driver's eyes, assisting the driver in driving the vehicle and preventing the driver from being distracted by looking down at the dashboard during driving, thereby improving driving safety and providing a better driving experience.

The following will combine the attached figures in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them.

FIG1 is a schematic diagram of the structure of a vehicle of an embodiment of the present application. As shown in FIG1 , the vehicle 100 includes a vehicle body and a head-up display 120 located in the vehicle body. FIG1 only shows the windshield 110 of the vehicle body and omits other components of the vehicle body. Other components of the vehicle body include, for example, a sensor system, a control system, an engine system, etc. The sensor system includes, for example, a global positioning system, a radar system, etc. The control system includes, for example, a steering unit for adjusting the direction of travel of the vehicle, a throttle controller for controlling the driving speed of the vehicle, and an engine controller.

The head-up display 120 includes a base 10, a picture generation unit (PGU) 20 located in the base 10, and a reflective component 30 located in the base 10. The base 10 is located, for example, on the center console of the vehicle 100. The picture generation unit 20 is used to emit image light L. The reflective component 30 is used to reflect the image light L emitted by the image generation unit 20 to the projection medium for imaging. The head-up display 120 is a windshield 110 type head-up display (Windshield HUD, WHUD). The windshield 110 is a projection medium. WHUD refers to a HUD that uses the windshield of the vehicle to display necessary information within the driver's field of vision. Generally speaking, WHUD can be included in the vehicle.

The image generation unit 20 includes a backlight module 26 and a liquid crystal display panel 23 located on the light-emitting side of the backlight module 26. The backlight module 26 is used to provide backlight to the liquid crystal display panel 23. The liquid crystal display panel 23 is used to receive backlight to form image light L to output various images, provide the driver with more diverse information, and enhance the driving experience. In some embodiments, the liquid crystal display panel 23 is, for example, 4.1 inches and has a refractive index of 1.52, but is not limited thereto.

The reflective assembly 30 is located between the windshield 110 and the image generating unit 20. The reflective assembly 30 includes at least one reflective mirror. In FIG1 , the reflective assembly 30 includes two reflective mirrors, namely a first reflective mirror 31 and a second reflective mirror 32. The first reflective mirror 31 is used to fold the light path, and the second reflective mirror 32 is used to magnify the image. The first reflective mirror 31 is located on the light-emitting side of the image generating unit 20, and is used to reflect the image light L of the image generating unit 20 to the second reflective mirror 32. The second reflective mirror 32 is used to reflect the image light L emitted by the first reflective mirror 31 to the windshield 110. After the image light L is reflected on the windshield 110, a target virtual image is generated in front of the windshield 110 and is observed by the driver's eye E.

It should be noted that, because the windshield 110 is in a tilted state, the image will be deformed, so at least one of the first reflector 31 and the second reflector 32 is a spherical mirror with adjustable position. In the embodiment shown in FIG1 , the first reflector 31 is a plane reflector with non-adjustable position, and the second reflector 32 is a curved reflector with adjustable position (e.g., a spherical mirror). By adjusting the position of the second reflector 32, the position of the image of the head-up display 120 on the projection medium is adjusted, so that the image can be displayed clearly and completely, so that the driver can see the virtual image projected by the HUD. The spherical mirror is, for example, a freeform concave mirror to magnify the image and provide a longer imaging distance.

In other embodiments, the first reflector 31 can be a spherical mirror with adjustable position, and the second reflector 32 can be a spherical mirror with non-adjustable position. By adjusting the position of the first reflector 31, the position of the HUD image on the projection medium can be adjusted to display the image clearly and completely.

In other embodiments, the reflective assembly 30 is not limited to including two reflective mirrors, for example, it may also include a third reflective mirror, a fourth reflective mirror, etc., and the reflective mirrors in the reflective assembly 30 may be convex reflective mirrors, concave reflective mirrors, or plane reflective mirrors.

The image generation unit 20 also includes a diffusion element 24 (shown in FIG. 4 ) located between the liquid crystal display panel 23 and the backlight module 26. The diffusion element 24 is used to diffuse the light emitted by the backlight module 26 and then project it onto the liquid crystal display panel 23 to improve the uniformity of the light projected onto the liquid crystal display panel 23. The diffusion element 24 is, for example, a diffuser film. The diffuser film is also called a uniform light plate, a diffuser sheet, a diffuser plate, etc.

In some embodiments, the diffusion element 24 is a volume diffusion film with PET as the base material, and its refractive index is approximately 1.49. When light passes through the diffusion film with PET as the base material, it will pass through the medium with a different refractive index, causing many refractions, reflections and scattering phenomena of the light, which can correct the light into a uniform surface light source to achieve the effect of optical diffusion, increase the light radiation area, and improve the uniformity of the light. In other embodiments, the material of the diffusion element 24 is not limited to this.

Please refer to FIG. 2A and FIG. 2B , the backlight module 26 includes a lamp panel 261, a plurality of reflectors 262, and a plurality of focusing lenses 263. The lamp panel 261 includes a circuit board 2611, a plurality of driver chips 2612 spaced apart on the circuit board 2611, and a plurality of light-emitting elements 2614 spaced apart on the circuit board 2611. The circuit board 2611 is, for example, a printed circuit board. The plurality of driver chips 2612 and the plurality of light-emitting elements 2614 are electrically connected to the circuit board 2611. The light-emitting element 2614 is, for example, a light-emitting diode, which is used to provide a light source and its own original light source path.

Specifically, the light-emitting element 2614 may be a Lambertian light-emitting diode, whose luminous brightness is, for example, 17.4 lumens (lm) at a current of 50 mA, but is not limited thereto.

A plurality of driver chips 2612 are arranged in a row along the first direction X in an area near the edge of the circuit board 2611. A plurality of light-emitting elements 2614 are arranged in a plurality of columns along the first direction X adjacent to the plurality of driver chips 2612, and are arranged in a plurality of rows along the second direction Y. The second direction Y intersects the first direction X. In FIG2A , the first direction X is perpendicular to the second direction Y. FIG2A schematically shows six rows of light-emitting elements 2614 and their corresponding reflectors 262 and focusing lenses 263.

A plurality of reflectors 262 are located on the circuit board 2611. Each reflector 262 surrounds and covers at least two light-emitting elements 2614. The reflector 262 is also called a reflective cup, a reflective cup or a reflective light cup. The inner surface of each reflector 262 includes a reflective surface S to reflect the light emitted by the light-emitting element 2614. The reflector 262 is used to correct the light-emitting angle of the light-emitting element 2614 and produce a focusing effect.

In some embodiments, the reflective surface S of the reflector 262 may be a spherical surface, an elliptical surface, or a concave surface formed by at least one free-form surface; or, the reflective surface S of the reflector 262 is formed by connecting a plurality of planes. In the embodiment shown in FIG. 2B , the reflector 262 is a trapezoidal table-type reflector 262. The tilt angle between the reflective surface S of the reflector 262 and the plane where the circuit board 2611 is located is β. The tilt angle is not less than 20 degrees (for example, 20 degrees, 24 degrees, 30 degrees) so that the light emitted by the light-emitting element 2614 converges to the light incident surface Sa of the focusing lens 263 after multiple reflections. The reflective surface S may be a surface coated with a reflective layer, and the material of the reflective layer is, for example, aluminum, and its reflectivity is not less than 80% (for example, 80%, 85%, 90%).

For the convenience of description, all the light-emitting elements 2614 covered by each reflector 262 are defined as a light source group G. That is, all the light-emitting elements 2614 included in the same light source group G are located in the same reflector 262. In the embodiment shown in FIG. 2B , each light source group G includes two light-emitting elements 2614. In other embodiments, the number of light-emitting elements 2614 in a light source group G may be greater than two.

Specifically, the plurality of light source groups G are arranged in an array of a plurality of rows and columns. All the light emitting elements 2614 in the same light source group G are connected in series, and all the light emitting elements 2614 in the same light source group G are electrically connected to the same driver chip 2612. Different light source groups G are connected in parallel. In other words, the light emitting elements 2614 corresponding to different light source groups G are electrically independent of each other. Therefore, the opening, closing and luminous brightness of all the light emitting elements 2614 in each light source group G can be independently controlled as a whole by the driver chip 2612 to which it is electrically connected, so that the luminous brightness of the area corresponding to each light source group G can be controlled individually. In addition, when the number of light source groups G is greater than the number of driver chips 2612, multiple light source groups G can be electrically connected to the same driver chip 2612. In other words, different light source groups G can be controlled by the same driver chip 2612, but the opening, closing and luminous brightness of each light source group G in the different light source groups G are independently controlled.

In the embodiment of the present application, the backlight module 26 includes a plurality of backlight areas (not shown), each of which corresponds to a light source group G, a reflector 262 and a focusing lens 263 corresponding to the light source group G. The backlight module 26 can adopt a local dimming technology to provide excellent backlight to the liquid crystal display panel 23. Specifically, the backlight module 26 can control the opening, closing and brightness of the light-emitting element 2614 in each light source group G through the driver chip 2612, thereby adjusting the brightness of each backlight area, so that the brightness and uniformity of different screen display areas of the liquid crystal display panel 23 can be adjusted.

The focusing lens 263 is located on a side of the reflector 262 away from the circuit board 2611. Each focusing lens 263 corresponds to a reflector 262, or in other words, each focusing lens 263 corresponds to a light source group G. The focusing lens 263 is used to focus the light emitted by the light-emitting element 2614 in the corresponding light source group G to amplify the light output brightness of the light-emitting element 2614, thereby improving the light output brightness of the backlight module 26.

In specific applications, each focusing lens 263 is one of a plano-convex lens, a biconvex lens, and a concave-convex lens. Each focusing lens 263 includes a light-entering surface Sa facing the light-emitting element 2614 and a light-emitting surface Sb opposite to the light-entering surface Sa. The light-emitting surface Sb is a convex surface, and the curvatures of the convex surfaces of the plurality of focusing lenses 263 are different. Specifically, the curvature of the convex surface of the focusing lens 263 can be adjusted by analogy with optical software to obtain the best effect of brightness and uniformity of different light-emitting areas of the backlight module 26, and then the optical parameters of the focusing lens 263 are specifically set in the actual product.

Specifically, a lens whose optical surface is a part of a spherical surface is a spherical lens, or in other words, a spherical lens refers to a lens with a constant curvature from the center of the lens to the edge of the lens. An aspherical lens is a lens whose curvature changes continuously from the center of the lens to the edge of the lens. In the embodiment of the present application, "curvature" refers to the degree of bending, and the curvature of a spherical surface can be expressed by curvature or radius of curvature. "Different curvatures" are relative to the same curvature. In the embodiment of the present application, when the convex surfaces of two focusing lenses are completely the same curved surfaces, the convex surfaces of the two focusing lenses are said to have the same curvature. In addition, as long as the convex surfaces of the two focusing lenses are not completely the same curved surfaces, the convex surfaces of the two focusing lenses are said to have different curvatures, that is, the curvatures are different.

In the embodiment shown in FIG. 2A and FIG. 2B , each focusing lens 263 is a plano-convex lens, and the light-emitting surface Sb of each focusing lens 263 is a spherical surface, and the radius of curvature of the spherical surface tends to increase from the center of the lens array to the edge of the lens array, or from the center of the array formed by the plurality of light source groups G to the edge of the array formed by the plurality of light source groups G, or from the center of the array formed by the plurality of light-emitting elements 2614 to the edge of the array formed by the plurality of light-emitting elements 2614.

In some embodiments, the number of light-emitting elements 2614 along the first direction X is greater than the number of light-emitting elements 2614 arranged along the second direction Y. That is, the first direction X is the long side of the array formed by the light-emitting elements 2614, and the second direction Y is the short side of the array formed by the light-emitting elements 2614. Along the first direction X, the radius of curvature of the focusing lens 263 corresponding to the light-emitting element 2614 close to the edge is greater than the radius of curvature of the focusing lens 263 corresponding to the light-emitting element 2614 close to the center. For example, the radius of curvature of each focusing lens 263 in the same column is equal. The radius of curvature of the focusing lens 263 in the first column and the last column is equal and greater than the radius of curvature of the focusing lens 263 located between the first column and the last column. In this way, the problem of uneven brightness in the display screen of the liquid crystal display panel 23 caused by the first column and the last column being far from the center of the display screen of the liquid crystal display panel 23 can be avoided.

In a specific embodiment, the material of each focusing lens 263 is polycarbonate (PC), the refractive index of each focusing lens 263 is 1.56, the radius of curvature of the spherical surface of the focusing lenses 263 in the first and last rows is 8.33 mm, and the radius of curvature of the spherical surface of the focusing lenses 263 in the middle row is 6.25 mm. Thus, by setting the radius of curvature of the plurality of focusing lenses 263 to be different, the best brightness increase effect and the best high uniformity effect can be achieved.

In other embodiments, the curvature radius of the focusing lenses 263 in the first and last rows is not limited to being adjusted. For example, the curvature radius of the focusing lenses 263 in the first two rows and the last two rows can be adjusted, so that the curvature radius of the spherical surface tends to increase in the direction from the center of the lens array to the edge of the lens array. In addition, the curvature radius of the focusing lenses 263 in different rows can be adjusted, so that the curvature radius of the spherical surface tends to increase in the direction from the center of the lens array to the edge of the lens array. Similarly, the curvature radius of the focusing lenses 263 in one or more rows can be adjusted. It can be understood that when the distribution of multiple focusing lenses is symmetrical, it is beneficial for the backlight module 26 to have a symmetrical light output distribution.

In other embodiments, when the focusing lens 263 is a biconvex lens or a concave-convex lens, the optical parameters of the biconvex lenses in different rows (or columns) can be adjusted to achieve the best brightness and uniformity in different light-emitting areas of the backlight module 26. For example, the curvature of the light-entering surface Sa of each biconvex lens is the same, and the curvature of the light-emitting surface Sb of different rows (or columns) is different; or, the curvature of the light-entering surface Sa of each concave-convex lens is the same, and the curvature of the light-emitting surface Sb of different rows (or columns) is different.

The plurality of light-emitting elements 2614 are arranged on the circuit board 2611 at unequal intervals. Correspondingly, the plurality of reflectors 262 are also arranged on the circuit board 2611 at unequal intervals, and the plurality of focusing lenses 263 are also arranged at unequal intervals. Moreover, in the area from the center to the edge of the circuit board 2611, the arrangement of the plurality of light-emitting elements 2614, the arrangement of the plurality of reflectors 262, and the arrangement of the plurality of focusing lenses 263 all show a trend from dense to sparse. Specifically, the distance between two adjacent focusing lenses 263 along the first direction X is a distance △X, and along the first direction X, from the center of the circuit board 2611 to both sides, the distance △X gradually increases.

It should be noted that in the related technology, the light-emitting elements of the backlight module are arranged uniformly and densely, so that when it is applied to HUD, when different screen areas of the liquid crystal display panel display different image information, the backlight emitted by the light-emitting elements in the screen area corresponding to the edge of the liquid crystal display panel may be wasted. In the embodiment of the present application, the light-emitting elements 2614 are arranged at unequal intervals, especially so that they can be sparser in the edge area of the circuit board 2611 relative to the middle area, and the light emitted by the light-emitting elements 2614 is converged by the reflector 262 and the focusing lens 263, and the regional lighting technology is used, so that a small number of light-emitting elements 2614 can achieve high brightness and high uniformity.

FIG3 is a three-dimensional schematic diagram of the image generation unit in FIG1. As shown in FIG3, the image generation unit 20 also includes a housing 21 for accommodating a liquid crystal display panel 23, a diffusion element 24, and a focusing lens 263 and a reflective cover 262 in a backlight module 26.

Specifically, the housing 21 includes a cover 211 and a frame 212. A through hole (i.e., a light outlet H1) is provided in the middle of the cover 211, and the light outlet H1 is used to emit image light L. After the liquid crystal display panel 23 is partially accommodated in the housing 21, its display surface is exposed from the light outlet H1.

The frame 212 is roughly a hollow cylinder. In FIG3 , the frame 212 is a hollow tetrahedron. The frame 212 has flanges extending from opposite ends, wherein the flange of the frame 212 close to the cover 211 is provided with a first mounting hole MH1, and correspondingly, the cover 211 is also provided with a first mounting hole MH1, so that the cover 211 and the frame 212 can be connected by a first fastener 221. The first fastener 221 is, for example, a screw. In addition, the flange of the frame 212 close to the light board 261 is provided with a second mounting hole MH2, and correspondingly, the circuit board 2611 is provided with a second mounting hole MH2, so that the cover 211 and the frame 212 can be connected by a second fastener 222. The second fastener 222 is, for example, a screw.

In addition, the light board 261 also includes a connector 2613. The connector 2613 is arranged in the edge area of the circuit board 2611 adjacent to the plurality of driver chips 2612. After the circuit board 2611 is connected to the frame 212, the plurality of driver chips 2612 and the connector 2613 are not contained in the frame 212, but are exposed from the frame 212. The connector 2613 electrically connects the plurality of driver chips 2612 and the liquid crystal display panel 23. In a specific embodiment, the connector 2613 is, for example, a power connector 2613, which is used to provide power to the liquid crystal display panel 23 and the plurality of light-emitting elements 2614, but is not limited thereto.

FIG4 is a three-dimensional exploded view of the image generation unit in FIG3. As shown in FIG4, a first mounting hole MH1 is respectively provided at the four corner edges of the cover 211, and a first mounting hole MH1 is correspondingly provided at the four corners of the flange of the frame 212 close to the cover 211, so that the corresponding positions of the cover 211 and the frame 212 are mechanically connected. The frame 212 and the cover 211 jointly define a receiving cavity R. The frame 212 includes an opening H2 close to the light board 261 and opposite to the light outlet H1. The receiving cavity R connects the light outlet H1 and the opening H2. A plurality of focusing lenses 263, a plurality of reflective covers 262 and a plurality of light-emitting elements 2614 are sequentially accommodated in the receiving cavity R, and the circuit board 2611 closes the opening H2 and is mechanically connected to the frame 212.

The image generation unit 20 also includes a pad 25. The pad 25 is in a U-shaped shape and is used to pad the diffusion element 24 and the liquid crystal display panel 23. The pad 25 is accommodated in the receiving cavity R. The diffusion element 24 and the liquid crystal display panel 23 are placed on the pad 25 in sequence and accommodated in the receiving cavity R. Among them, the liquid crystal display panel 23 is partially accommodated in the receiving cavity R, and one side of its display screen is exposed from the light outlet H1.

The plurality of focusing lenses 263 are a whole layer. The plurality of focusing lenses 263 are formed by, for example, integral injection molding or CNC machining.

In addition, the plurality of reflectors 262 is also a whole layer. The whole layer of the plurality of reflectors 262 includes a plurality of depressions, each depression corresponding to a reflector 262. Specifically, each depression is roughly in the shape of a trapezoidal table and the two opposite sides of each depression are connected. Among them, the opening of each depression close to the light board 261 is closed by the circuit board 2611, so that each reflector 262 surrounds at least two light-emitting elements 2614. The opening of each depression close to the focusing lens 263 is closed by the focusing lens 263, so that the light emitted by the light-emitting element 2614 is reflected by the reflector 262 to the light incident surface Sa of the focusing lens 263.

FIG5 is a schematic plan view of the light panel in the image generation unit shown in FIG4. FIG6 is a top view of the light panel and the focusing lens in the image generation unit shown in FIG4. In the embodiment of the present application, the plurality of light-emitting elements 2614 are arranged at non-equidistant intervals, the plurality of focusing lenses 263 are arranged at non-equidistant curvatures, and the regional lighting technology is used to make the backlight module 26 have high brightness and high uniformity. The following specifically describes the arrangement of the plurality of light-emitting elements 2614 and the plurality of focusing lenses 263 in conjunction with FIG5 and FIG6.

As shown in FIG5 , there are a total of six driver chips 2612 on the light board 261, and each light source group G includes two light-emitting elements 2614. The multiple light source groups G are arranged as M columns along the X-axis and as N rows along the Y-axis (M is an integer greater than or equal to 2, and N is an integer greater than or equal to 2). In FIG5 , the light source groups G are arranged as 6 rows and 12 columns (M=12, N=6), with a total of 144 light-emitting elements 2614. The light-emitting elements 2614 in every two columns of the light source groups G are connected to a corresponding driver chip 2612. The row spacing between any two adjacent light source groups G in the same row is defined as dy. The column spacing between any two adjacent light source groups G in the same column is defined as dx. In the direction from the center of the array to the edge of the array, at least one of dy and dx tends to increase. That is, dx may gradually increase in the direction from the center of the array to the edge of the array; dy may gradually increase in the direction from the center of the array to the edge of the array; or dx may gradually increase in the direction from the center of the array to the edge of the array while dy gradually increases.

In FIG5 , the array formed by the plurality of light-emitting elements 2614 is symmetrically distributed in the X-axis direction and the Y-axis direction, and dx and dy gradually increase from the coordinate origin outward. It should be noted that in the embodiment of the present application, "gradually increasing" and "increasing trend" refer to the overall change trend of the distance from small to large, which allows the distance to maintain a constant value in the process of changing from small to large.

As shown in FIG6 , the plurality of focusing lenses 263 are arranged in N rows and M columns, wherein the first focusing lens 263 in the first row to the last focusing lens 263 in the first row (i.e., the Mth focusing lens 263) are named G11, G12, ... G1M in sequence; and similarly, the first focusing lens 263 in the Nth row to the last focusing lens 263 in the Nth row (i.e., the Mth focusing lens 263) are named GN1, GN2 ..., GNM, respectively. In FIG6 , the plurality of focusing lenses 263 are arranged in 6 rows and 12 columns (M=12, N=6). A rectangular coordinate system is established with the center of the array formed by the plurality of focusing lenses 263 as the coordinate origin, the direction of the row as the X axis, and the direction of the column as the Y axis. The multiple focusing lenses 263 are symmetrical about the X-axis and symmetrically distributed about the Y-axis. Extending from the coordinate origin to the positive direction of the X-axis, the distance between the multiple focusing lenses 263 gradually increases. Extending from the coordinate origin to the positive direction of the Y-axis, the distance between the multiple focusing lenses 263 gradually increases.

In a specific embodiment, the following formula can be used to represent the position of the focusing lens 263. For the first and fourth quadrants, the horizontal coordinate value (unit: mm) of each focusing lens 263 is 9.042A-7.6, where A is the number of rows, and the value range of A in FIG6 is 7, 8, 9, 10, 11, and 12. It can be understood that the horizontal coordinate value of each focusing lens 263 in the second and third quadrants can be obtained by mirroring according to the symmetric relationship. Regarding the longitudinal coordinate value of each focusing lens 263, the longitudinal coordinate value (unit mm) of each focusing lens 263 in the 7th column is -9.2B+32.2; the longitudinal coordinate value (unit mm) of each focusing lens 263 in the 8th and 9th columns is -9.485B+33.2; the longitudinal coordinate value (unit mm) of each focusing lens 263 in the 10th column is -9.714B+34; the longitudinal coordinate value (unit mm) of each focusing lens 263 in the 11th and 12th columns is -9.994B+34.98. Among them, B is the number of rows, and the value range of B in Figure 6 is 1, 2, 3, 4, 5, 6. It can be understood that the number and spacing of the focusing lenses 263 are not limited to this.

The following is a description of the brightness and uniformity of the image generating unit 20 of the embodiment of the present application in combination with Figures 7 to 15. Among them, Figures 7 to 15 are obtained by analogy with optical software (such as Light Tools). Specifically, the brightness uniformity (display area - 100%) of the image generating unit 20 obtained is 66.8%, and the central brightness is 835000nit. The horizontal field of view angle is ±20.5 degrees, and the vertical field of view angle is ±4 degrees. With the transmittance of the liquid crystal display panel 23 being 0.072, the reflectivity of the reflective component 30 being 0.93, the transmittance of the cover 211 being 0.8, and the reflectivity of the windshield 110 being 0.3, the estimated brightness is calculated to be 835000*0.072*0.93*0.8*0.3=10518nit. It can be seen that the image generation unit 20 of the embodiment of the present application has high brightness (the brightness of the light output of the known image generation unit is much less than 10,000 nit).

As shown in FIG7, when all light source groups G are turned on, the central brightness of multiple areas is higher than 800,000 nit, and the brightness distribution in the entire screen is relatively uniform. In addition, as shown in FIG8 to FIG15, the backlight module 26 can also be matched with the driver chip 2612 according to the position of the light source group G, so that the liquid crystal display panel 23 can present different screen display areas, not limited to full-screen display.

For example, the multiple light source groups G in the middle area of the light board 261 can be controlled to emit light. FIG8 is a brightness diagram obtained when the 6 rows and 8 columns of light-emitting elements 2614 in the middle area of the image generation unit 20 are lit, and FIG9 is a brightness diagram obtained by analogy when the 2 rows and 4 columns of light-emitting elements 2614 in the middle area of the image generation unit 20 are lit.

Alternatively, the light source groups G in different areas of the light board 261 can be controlled to emit light at intervals. Figures 10 to 15 are analogous brightness diagrams obtained when the image generation unit 20 lights up the light-emitting elements 2614 in the horizontal direction in intervals of rows, lights up the light-emitting elements 2614 in the vertical direction in intervals of rows, lights up the light-emitting elements 2614 in the side edges and the center area, lights up the light-emitting elements 2614 in the diagonal area, lights up the light-emitting elements 2614 in the upper and lower edge areas, and lights up the light-emitting elements 2614 in the half area. It can be seen from Figures 7 to 15 that the image generation unit 20 has high brightness and high uniformity. It is understandable that the regional lighting mode that can be realized by the image generation unit 20 is not limited to those shown in Figures 7 to 15.

In summary, in the backlight module of the embodiment of the present application, the light of the light-emitting element is gathered to the focusing lens by setting a reflector, and the brightness of the light output is increased by the focusing lens. The light of the focusing lens is further transmitted to the liquid crystal display panel through the diffusion element to present the effect of uniform output and high brightness. In addition, in the embodiment of the present application, the backlight module can achieve the effect of regional dynamic display by local lighting technology according to the arrangement of the light source group, so that the HUD can effectively save energy and have a better contrast. Moreover, compared with the known backlight module with full-surface lighting, the problem of pre-overbrightness can also be avoided.

The above implementations are only used to illustrate the technical solution of the present invention and are not intended to limit it. Although the present invention is described in detail with reference to the preferred implementations, ordinary technicians in this field should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

20: Image generation unit

21: Shell

211: Cover

212:Frame

221: First fastener

222: Second fastener

23: LCD panel

24: Diffusion element

25: Pad

26: Backlight module

261: Light board

2611: Circuit board

2612:Drive chip

2613: Connector

2614: Light-emitting element

262:Reflector

263: Focusing lens

H1: light outlet

H2: Opening

R: Accommodation cavity

MH1: First mounting hole

MH2: Second mounting hole

S: Reflective surface

Sa: light incident surface

Sb: light-emitting surface

Claims (7)

A backlight module comprises: a circuit board; a plurality of light-emitting elements, which are arranged on the circuit board at intervals, each of which is electrically connected to the circuit board, and the plurality of light-emitting elements are arranged on the circuit board at unequal intervals, wherein the row interval between any two adjacent light source groups in the same row is defined as dy; and the column interval between any two adjacent light source groups in the same column is defined as dx; wherein, in a direction from the center of the array to the edge of the array, at least one of dy and dx tends to increase; A plurality of reflectors, located on the circuit board, each of which covers at least two of the light-emitting elements, defining all of the light-emitting elements covered by each of the reflectors as a light source group, the plurality of light source groups are arranged in an array of a plurality of rows and a plurality of columns, and the opening, closing and luminous brightness of all of the light-emitting elements in each of the light source groups can be independently controlled as a whole; and a plurality of focusing lenses, located on a side of the plurality of reflectors away from the plurality of light-emitting elements, and each of the focusing lenses is aligned with one of the light source groups. According to the backlight module described in claim 1, each of the focusing lenses is one of a plano-convex lens, a biconvex lens, and a concave-convex lens; each of the focusing lenses includes a light incident surface facing the light-emitting element and a light emitting surface opposite to the light incident surface, the light emitting surface is a convex surface, and the curvatures of the convex surfaces of the plurality of focusing lenses are different. According to the backlight module described in claim 2, each of the focusing lenses is a plano-convex lens, and the light-emitting surface of each of the focusing lenses is a spherical surface, and the radius of curvature of the spherical surface tends to increase in the direction from the center of the array to the edge of the array. An image generating unit, comprising: a liquid crystal display panel for forming image light; and a backlight module according to any one of claims 1 to 3, located on one side of the liquid crystal display panel and providing the liquid crystal display panel with the backlight required for forming the image light, wherein the image generating unit further comprises a housing; the housing comprises a light outlet for emitting the image light, an opening opposite to the light outlet, and a receiving cavity connecting the light outlet and the opening; the plurality of light emitting elements, the plurality of reflective covers, and the plurality of focusing lenses are received in the receiving cavity, and the circuit board closes the opening; the liquid crystal display panel is partially received in the receiving cavity. According to the image generation unit described in claim 4, the image generation unit further includes a diffusion element, and the diffusion element is located between the liquid crystal display panel and the plurality of focusing lenses. A head-up display, comprising: an image generating unit according to any one of claims 4 to 5; and a reflective component for reflecting the image light to a projection medium for imaging. A vehicle comprising: a windshield; and a head-up display according to claim 6, wherein the windshield is the projection medium.