Backlight illumination system for head-up display device, head-up display device and motor vehicle

Abstract

The utility model discloses a backlight illumination system for a head-up display device. The backlight illumination system comprises an LED array, a lens group and an LCD screen, and the LED array, the lens group and the LCD screen are arranged from bottom to top. The LED array comprises one or more LED lamp beads; the lens group comprises a spherical lens, a free-form surface lens and a Fresnel lens; the spherical lens, the free-form surface lens and the Fresnel lens are arranged from bottom to top; the lens group is used for shaping the light rays emitted by the LED array for three times so as to gradually reduce the divergence angle of the light rays emitted by the LED array, the light rays are irradiated to the Fresnel lens, the light ray irradiation area is finally adjusted and homogenized, and the light rays are irradiated to the LCD screen after being emitted. The utility model also discloses a head-up display device and a motor vehicle.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the field of head-up display device backlight technology, and relates to a backlight illumination system for a head-up display device, a head-up display device and a motor vehicle. BACKGROUND

[0002] The head-up display system HUD can be divided into three schemes of TFT-LCD, DLP and LCoS according to different light machine projection technology routes: among them, the TFT-LCD technology is mature and has low cost, and is widely used in W-HUD; the DLP has excellent performance and can prevent sunlight from flowing back, and is considered as the preferred scheme of AR-HUD, but has technical monopoly, high cost, unstable supply and other factors; the LCoS can get rid of the intellectual property monopoly of Texas Instruments (TI) on DLP, but has the limitation that customization cannot be realized due to the immaturity of the technology. Therefore, LCD used as an image source is the preferred mature scheme at present, and is worthy of further research. With the development of HUD technology, backlights with high efficiency, high brightness, high uniformity and low cost are paid more and more attention.

[0003] In the technical route of the HUD system using LCD as an image source, the LCD does not actively emit light or has too small light emission brightness, and a backlight system needs to provide high brightness to illuminate the LCD, especially in the case of strong ambient light, the brightness requirement of the backlight is higher, and at the same time, the uniformity requirement of the backlight is also high for the overall display effect of the HUD. At present, the principles of all backlight systems are basically as follows: first, collimate the LED light source; and then shape, expand and uniformize the collimated light. The principle used in the Chinese utility model patent: Collimating lens and microarray Fresnel lens combined HUD backlight system (CN111025642B) is also the same. The light is collimated and expanded and uniformized once. The problems mainly include: 1. Single lamp beads can achieve uniform light and high energy utilization rate, but the splicing of multiple lamp beads will cause serious splicing problems, which is easy to cause dark area problems on the surface of the LCD; 2. If the lens array is spliced in a hexagonal or rectangular shape, bright stripes are easy to appear, which causes bright area problems; 3. For a large-size LCD, in order to obtain good uniformity, the LED arrangement spacing is close and the number is large, which aggravates the heat dissipation difficulty problem; 4. Splicing will cause changes in light angle and low energy utilization rate; and the like. UTILITY MODEL CONTENTS

[0004] In order to solve the problems in the prior art, the utility model aims to provide a backlight illumination system for a head-up display device HUD, which obtains an LCD backlight with good uniformity by shaping the light emitted by the LED array three times.

[0005] The backlight illumination system disclosed by the utility model includes: LED array, lens group, LCD screen, set from bottom to top LED array, lens group, LCD screen;

[0006] Among them, the lens group includes spherical lens, free-form lens, Fresnel lens; the spherical lens, the free-form lens, the Fresnen lens are set from bottom to top; the lens group carries out three times shaping to the light ray that the LED array emits;

[0007] The LED array includes one or more LED lamp beads, provides light source for the backlight illumination system;The divergence angle of the light ray that the LED lamp bead emits is 30 ° ~ 180 °;The number and spacing of the LED array are according to the size of the LCD screen to be illuminated, the brightness of the virtual image in the backlight illumination system, the imaging uniformity, the cost and so on requirement selects more suitable arrangement;

[0008] When the size of the LCD to be illuminated is larger, and / or, the virtual image brightness is required to be higher, and / or, the imaging uniformity is required to be higher, more and more dense LED lamp beads need to be set;But the more the number of LED lamp beads is, the cost is relatively higher, and it needs to be considered comprehensively;

[0009] In the setting of the LED array, it is necessary to consider that there is no interference between the spherical lens and the spherical lens, and there is no interference between the free-form lens and the free-form lens;

[0010] In one specific embodiment, the LED array includes a single LED lamp bead in a row and a column;Or,

[0011] In one specific embodiment, the LED array includes a plurality of LED lamp beads in a single row and multiple columns;Or,

[0012] In one specific embodiment, the LED array includes a plurality of LED lamp beads in multiple rows and a single column;Or

[0013] In one specific embodiment, the LED array includes a plurality of LED lamp beads in multiple rows and multiple columns;

[0014] The spherical lens is arranged above the lamp bead of the LED array, and the number thereof corresponds to the number of the LED lamp bead, which is one or more, and one spherical lens is arranged above each LED lamp bead;The diameter of the spherical lens is greater than or equal to the size of the LED lamp bead, and the distance between the spherical lens and the LED lamp bead is 2-10 mm;The spherical lens includes a plane and a spherical surface, wherein the plane of the spherical lens is the light entrance surface, and the spherical surface of the spherical lens is the light exit surface;The divergence angle of the light ray emitted by the LED lamp bead is reduced after passing through the spherical lens, and the divergence angle is reduced to 80 °-100 °.

[0015] The free-form lens is arranged above the spherical lens, comprising a plane and a free-form surface, the plane of the free-form lens is the light entrance surface, and the free-form surface of the free-form lens is the light exit surface; the plane of the free-form lens is opposite to the spherical surface of the spherical lens; the distance between the free-form lens and the spherical lens is 0-10 mm; after passing through the free-form lens, the divergence angle of the light is further reduced, and the divergence angle of the collimated light is 2-5°;

[0016] When the plane of the free-form lens is in contact with the spherical surface of the spherical lens (i.e. the distance is 0), the size of the free-form lens is small, the area illuminated by a single LED lamp bead is small, and the free-form lens is suitable for a scene where the number of LED lamp beads is large and a single LED lamp bead does not need to illuminate a large area and the uniformity requirement is high; or,

[0017] When the plane of the free-form lens is not in contact with the spherical surface of the spherical lens (i.e. the distance is not 0), the size of the free-form lens is relatively large, the area illuminated by a single LED lamp bead is large, and the free-form lens is suitable for a scene where the number of LED lamp beads is small and the cost requirement is high and the cost needs to be reduced;

[0018] The free-form surface of the free-form lens is a polynomial aspheric surface or an even aspheric surface;

[0019] The free-form surface of the polynomial aspheric surface is represented by the following formula:

[0020]

[0021] wherein z represents the sag of the free-form surface, c is the reciprocal of the curvature, k is the conic coefficient, and α1, α2, α3, α4, α5, α6, α7, α8, …, αn represent the aspheric coefficients; or 16 r represents the diameter of the free-form surface; or,

[0022] When the coefficient of the odd power term in the free-form surface formula of the polynomial aspheric surface is 0, the free-form surface formula is that of an even aspheric surface.

[0023] The Fresnel lens is arranged above the free-form lens, and the size of the Fresnel lens can cover the entire size of the LCD screen, so that the Fresnel lens can be used for beam expansion and shaping; the plane without microstructure of the Fresnel lens is the light entrance surface, and the other surface is the convex Fresnel surface, which is the light exit surface of the Fresnel lens;

[0024] The distance between the Fresnel lens and the free-form lens is 2-40 mm, and the distance between the Fresnel lens and the LCD screen is 60-120 mm;

[0025] The height of the Fresnel lens is lower than the lowest point of the LCD screen; the height of the entire backlight affects the volume of the entire backlight, and the smaller the volume, the lower the volume requirement for the HUD, and the smaller the volume, the better; and / or,

[0026] The collimation degree of the light rays affects the beam expansion and shaping of the Fresnel lens, and affects the size and uniformity of the area illuminated by the backlight; the Fresnel lens requires high collimation of the incident light, and the higher the collimation, the better.

[0027] The LCD screen is arranged above the Fresnel lens and does not contact the Fresnel lens, and the reference angle of the LCD screen forms an angle of 15° or 20° with the horizontal plane, which can be changed within a range of 10°-30°.

[0028] The utility model also provides a kind of method for generating uniform imaging light, the method includes the following steps: LED array emits light rays with divergence angle of 30°-180°, the light rays continue to propagate forward after divergence angle is reduced to 80°-100° by spherical lens, after free-form surface lens, light rays are collimated, divergence angle is 2°-5° and propagates forward;The light rays emitted from free-form surface lens enter Fresnel lens to be homogenized and shaped and expanded, so that the angle of light rays matches HUD imaging light, and finally uniformly irradiate to the surface of LCD screen;

[0029] In HUD imaging design, the light rays emitted by the LCD screen have a certain angle, within 80° in long side direction and within 60° in short side direction.Backlight design, the light ray angle of backlight can cover this angle in long side direction and short side direction, and the ideal state is that the angles are completely matched.

[0030] The utility model also provides a kind of head-up display device, and the head-up display device includes the backlight illumination system described above.

[0031] The utility model also provides a kind of motor vehicle, and the motor vehicle includes the backlight illumination system and / or head-up display device described above.

[0032] The utility model has the advantages that the utility model solves the problem of dark area and bright area caused by LED collimation and splicing, and more uniform illumination effect can be obtained.In the utility model, one LED corresponds to one spherical lens and one free-form surface lens, the light rays emitted by the LED are shaped three times, respectively including spherical lens, free-form surface lens and Fresnel lens, and after the light rays are fully fused, there is no blind area that is not irradiated by light rays or area that is irradiated by overlapping light rays, and the lenses do not intersect each other, so that there is no dark area and bright area after diffusing to the LCD surface, and the uniformity can reach more than 85%, while in the prior art, the uniformity is 55%-90%.

[0033] Since the lens does not need to be spliced, the spacing between the LED lamp beads does not need to be very close, which is beneficial to heat dissipation. Meanwhile, since the lens does not need to be spliced, the light angle will not be damaged and will not be too much cross, the energy utilization rate is higher, which can reach more than 70%, while the energy utilization rate in the prior art is only 50% to 70%.

[0034] The light shaping part in the utility model has simple structure, and the whole structure (lens group) only includes three parts, without the need of making a large number of microstructures, such as stripe beam-shaped expansion structure, on the surface of the expansion mirror.

[0035] The Fresnel lens used in the utility model is a conventional Fresnel lens, which has mature production technology, is easy to mass produce, and is low in cost. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical scheme in the embodiments of the utility model or the prior art, the drawings needed to be used in the embodiment or the prior art description will be briefly introduced below, and obviously, the drawings in the following description are only some embodiments of the utility model, and other drawings can be obtained according to the drawings for those skilled in the art without creative labor.

[0037] Figure 1 It is the structure schematic diagram of the backlight illumination system of the utility model.

[0038] Figure 2 It is the front view of the backlight illumination system of the utility model.

[0039] Figure 3 It is the left view of the backlight illumination system of the utility model.

[0040] Figure 4 It is the path schematic diagram of the light emitted by the LED array and passing through the spherical lens and the free-form surface lens of the utility model.

[0041] Figure 5 It is the top view of the Fresnel lens of the utility model.

[0042] Figure 6 It is the top view of one kind of LED array in the specific embodiment of the utility model.

[0043] Figure 7 It is the surface space luminance schematic diagram of the LCD in the embodiment of the utility model.

[0044] Figure 8 It is the surface illuminance schematic diagram of the LCD in the embodiment of the utility model.

[0045] Figure 9 It is the uniformity test method schematic diagram in the embodiment of the utility model. DETAILED DESCRIPTION

[0046] The utility model will be further explained in detail in combination with the following specific embodiments and drawings. The process, condition, experimental method and the like of implementing the utility model are the general knowledge and common sense in the art except for the following specially mentioned contents, and the utility model has no special limited contents.

[0047] The utility model provides a kind of backlighting system for HUD, its system is mainly by five parts, from bottom to top, it is arranged in a certain order LED lamp pearl, primary spherical lens, secondary free-form lens, Fresnel lens and LCD screen, as shown in it, the light with larger divergence angle emitted by LED lamp pearl is irradiated to primary spherical lens, light is shaped initially, divergence angle is initially reduced, then the light with reduced divergence angle is irradiated to secondary free-form lens again, so that the divergence angle of light changes and is homogenized, finally light is irradiated to Fresnel lens, carries out the last adjustment and homogenization to light irradiation area, light is emitted and irradiated to LCD screen. Figure 4

[0048] The utility model provides a kind of backlighting system for HUD, as shown in it, the backlighting system includes LED array, lens group, LCD screen, the LED array, lens group, LCD screen are set from bottom to top; Figures 1-3

[0049] The LED array includes one or more LED lamp pearls;

[0050] The lens group includes spherical lens, free-form lens, Fresnel lens;The spherical lens, the free-form lens, the Fresnel lens are set from bottom to top;The lens group carries out three times shaping to the light emitted by the LED array.

[0051] The LED lamp pearl is a row of one column, single row multiple columns, multiple rows single column or multiple rows multiple columns;The divergence angle of light emitted by the LED lamp pearl is 30 °~180 °;Specifically, in one specific embodiment, the LED lamp pearl is arranged in five rows and three columns, as shown in it. Figure 6

[0052] The spherical lens is arranged above the LED lamp pearl, the number of the spherical lens matches the number of the LED lamp pearl and is equal to one or more;The diameter of the spherical lens is greater than or equal to the size of the LED lamp pearl;The spherical lens includes plane and spherical surface, the plane of the spherical lens is light entrance surface, the spherical surface of the spherical lens is light exit surface, and the divergence angle of light passing through the spherical lens is 80 °~100 °.

[0053] ​​​The freeform lens is disposed above the spherical lens and includes a plane and a freeform surface. The plane of the freeform lens is the incident light surface, and the freeform surface is the exit light surface. The plane of the freeform lens is opposite to the spherical surface of the spherical lens. The distance between the freeform lens and the spherical lens is 0-10mm. After passing through the freeform lens, the collimated light divergence angle is 2°-5°.

[0054] The freeform surface of the freeform lens is a polynomial aspherical or an even-order aspherical.

[0055] The freeform surface shape of a polynomial aspheric surface is expressed by the following formula:

[0056]

[0057] Where z represents the freeform surface elevation, c is the curvature, the reciprocal of the radius, k is the conic coefficient, and α1, α2, α3, α4, α5, α6, α7, α8, ..., α 16 , where is the aspherical coefficient, and r is the diameter of the freeform surface; or,

[0058] When the coefficient of the odd-power term in the formula for the freeform surface shape of a polynomial aspheric surface is 0, then it is the formula for the freeform surface shape of an even-power aspheric surface.

[0059] Compared to conventional polynomial aspheric freeform surface types, the effect is better when the coefficients of odd-degree terms in the formula are set to 0, i.e., when using even-degree aspheric freeform surface types.

[0060] like Figure 5 As shown, the Fresnel lens is positioned above the freeform lens, with the flat surface without microstructures serving as the light-incident surface and the convex Fresnel surface serving as the light-outceasing surface; the distance between the Fresnel lens and the freeform lens is 2–40 mm, and the distance between the Fresnel lens and the LCD screen is 60–120 mm.

[0061] The LCD screen is positioned above the Fresnel lens, and the reference angle of the LCD screen forms an angle of 15° or 20° with the horizontal plane. The LCD screen can vary within a range of 10° to 30° with the horizontal plane.

[0062] Example 1

[0063] The embodiment provides a backlight illumination system for a head-up display device, the backlight illumination system is suitable for a 3.1-inch LCD, 2*6 LED lamp beads are contained in an LED array in the backlight illumination system, the distance between single LED lamp beads and the LED lamp beads is 15mm, the radius of a corresponding first-order spherical lens is 4mm, the surface type of a second-order free-form lens is an even aspheric surface, the surface type formula is described by the following formula, and the coefficient of an odd power term in a polynomial aspheric free-form surface type formula is 0:

[0064]

[0065] coefficient mouth diameter 18.15805184 conic coefficient .0.674899232 curvature 0.193175367 4th order -3.57E-05 6th order -3.78E-07 8th order -5.03E-09 10th order -3.40E-11 12th order .5.82E-14 14th order 2.25E-16 16th order 4.75E-18

[0066] The distance from the LCD screen to the surface of the Fresnel lens is 100mm; the light emitted by the LED array is emitted at a divergence angle of 120°, the divergence angle is reduced to 80° after passing through the spherical lens, the divergence angle is reduced to 3° again after passing through the free-form lens, and the light is emitted into the Fresnel lens; and the light is adjusted and homogenized by the Fresnel lens and then emitted to the LCD screen.

[0067] Figure 7 For the spatial brightness graph in the embodiment, it can be seen that the main energy (red area) of the backlight is concentrated in a 70*42mm area, the backlight is suitable for a 3.1-inch backlight (68.4*41.04mm), the energy is relatively concentrated, the utilization rate is high, and the uniformity is good.

[0068] Figure 8 For the LCD surface illuminance graph in the embodiment, it can be seen from the slice graph that the backlight has good uniformity, clear interface, high energy utilization rate, the main energy (red area) is concentrated in a 70*42mm area, the backlight is suitable for a 3.1-inch backlight (68.4*41.04mm), and the energy is relatively concentrated.

[0069] In the embodiment, the uniformity of the light irradiation area is determined through the following steps, as shown in the following formula: Figure 9 Nine circle points are taken on the LCD screen according to the above graph, the diameter of the circle points ranges between 0.2V and 0.2H (the minimum value between the two is recommended), the brightness values of the nine points are measured, the minimum value is divided by the maximum value to convert into percentage, and then the uniformity can be obtained.

[0070] Embodiment 2

[0071] The embodiment provides a backlight illumination system for a head-up display device, the backlight illumination system is suitable for a 4.1-inch LCD, 3*6 LED lamp beads are contained in an LED array in the backlight illumination system, the distance between single LED lamp beads is 14.5 mm, the radius of a corresponding first-order spherical lens is 4 mm, the surface type of a second-order free-form lens is even aspheric, the surface type formula is described by the following formula, and the coefficient of an odd power term in a polynomial aspheric free-form surface type formula is 0:

[0072]

[0073] mouth diameter 7 conic coefficient -0.2034344 curvature 0.28161155 4th order 0.01550345 6th order 0.00021122 8th order 6.51E-06 10th order 2.23E-07 12th order -4.34E-09 14th order -2.77E-10 16th order -3.59E-11

[0074] The distance from the LCD screen to the surface of the Fresnel lens is 110 mm; the light emitted by the LED array is emitted at a divergence angle of 110 degrees, the divergence angle is reduced to 90 degrees after the spherical lens, the divergence angle is reduced to 5 degrees again after the free-form lens, and the light is emitted into the Fresnel lens; and the light is emitted onto the LCD screen after adjustment and homogenization of the Fresnel lens.

[0075] Embodiment 3

[0076] The embodiment provides a backlight illumination system for a head-up display device, the backlight illumination system is suitable for a 4.1-inch LCD, 3*6 LED lamp beads are contained in an LED array in the backlight illumination system, the distance between single LED lamp beads and LED lamp beads is 13 mm, the radius of a corresponding first-order spherical lens is 3 mm, the surface type of a second-order free-form lens is even aspheric, the surface type formula is described by the following formula, and the coefficient of an odd power term in a polynomial aspheric free-form surface type formula is 0:

[0077]

[0078] mouth diameter 8.30360087 conic coefficient -0.0992792 curvature 0.25378646 4th order 0.00084672 6th order 3.94E-05 8th order -5.67E-06 10th order 2.35E-09 12th order -6.55E-09 14th order -9.65E-10 16th order 7.62E-11

[0079] The distance from the LCD screen to the surface of the Fresnel lens is 120 mm; the light emitted by the LED array is emitted at a divergence angle of 130 degrees, the divergence angle is reduced to 80 degrees after the spherical lens, the divergence angle is reduced to 3 degrees again after the free-form lens, and the light is emitted into the Fresnel lens; and the light is emitted onto the LCD screen after adjustment and homogenization of the Fresnel lens.

[0080] Embodiment 4

[0081] The embodiment provides a backlight illumination system for a head-up display device, the backlight illumination system is suitable for a 4.1-inch LCD, 3*7 LED lamp beads are contained in an LED array in the backlight illumination system, the distance between single LED lamp beads and LED lamp beads is 10mm, the radius of a corresponding first-order spherical lens is 3mm, the surface type of a second-order free-form surface lens is an even aspheric surface, the surface type formula is described by the following formula, and the coefficient of an odd power term in a polynomial aspheric free-form surface surface type formula is 0:

[0082]

[0083] mouth diameter 7 conic coefficient -0.2039016 curvature 0.28117914 4th order 0.0154463 6th order 2.11E-04 8th order 5.89E-06 10th order 1.82E-07 12th order -6.42E-09 14th order -3.21E-10 16th order -5.65E-11

[0084] The distance from the LCD screen to the surface of the Fresnel lens is 100mm; the light emitted by the LED array is emitted at a divergence angle of 105 degrees, the divergence angle is reduced to 85 degrees after the spherical lens, the divergence angle is reduced to 4 degrees again after the free-form surface lens, and the light is emitted into the Fresnel lens; the light is adjusted and homogenized by the Fresnel lens and is emitted to the LCD screen.

[0085] In the description of the utility model, it is to be explained that, if the word such as the direction position appears, the direction or position relation that it indicates is based on the direction or position relation shown in the drawing, just is for the convenience of describing the utility model and simplifying the description, and is not the indication or the hint that the device or the element indicated must have the specific direction, constructs and operates with the specific direction, therefore can not be understood as the restriction of the utility model.

[0086] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can include that the first and second features are in direct contact, or the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the first feature is higher in horizontal height than the second feature. The first feature "under" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the first feature is lower in horizontal height than the second feature.

[0087] The present disclosure provides many different embodiments or examples for implementing different structures of the present application. For simplicity of the present disclosure, the embodiments of the present application are described in terms of particular examples and / or implementations. Of course, they are merely examples and are not intended to limit the present application in any manner. Descriptions of well-known functions and constructions can be omitted for clarity and conciseness. The descriptions of the various embodiments of the present application are intended to be illustrative, not limiting. Indeed, many modifications of the embodiments, in addition to those described herein, will be apparent to those of ordinary skill in the art, from the disclosure of this application. Further, it is intended that the methods of the present application can be performed by more than one controller or processor. For example, the functions of the controller can be split between two or more controllers or processors. In addition, the various embodiments presented herein are not necessarily mutually exclusive. For example, the various embodiments can be combined in any way. Moreover, the various embodiments presented herein can be implemented in software and / or hardware. For example, the various embodiments can be implemented in one or more computer programs executing on one or more programmable computer systems.

[0088] The scope of the present application is not limited to the above embodiments. Any changes and advantages that can be thought of by those skilled in the art without departing from the spirit and scope of the present application are included in the present application, and are protected by the appended claims.

Claims

1. A backlighting system for a heads-up display device, characterized by, The backlight illumination system comprises an LED array, a lens group, and an LCD screen, which are arranged from bottom to top. The LED array comprises one or more LED lamp beads, which are arranged in one row and one column, one row and multiple columns, multiple rows and one column, or multiple rows and multiple columns. The lens group comprises spherical lenses, free-form lenses, and Fresnel lenses, which are arranged from bottom to top.

2. The backlighting system of claim 1, wherein, The spherical lenses or the free-form lenses do not interfere with each other.

3. The backlighting system of claim 1, wherein, The spherical lenses are arranged above the LED lamp beads, and the number of the spherical lenses corresponds to the number of the LED lamp beads. The spherical lenses comprise planes and spherical surfaces, the planes of the spherical lenses are light-incoming surfaces, the spherical surfaces of the spherical lenses are light-outgoing surfaces, and the divergence angle of the light passing through the spherical lenses is 80°-100°.

4. The backlighting system of claim 1, wherein, The free-form lenses are arranged above the spherical lenses, and comprise planes and free-form surfaces, the planes of the free-form lenses are light-incoming surfaces, and the free-form surfaces of the free-form lenses are light-outgoing surfaces.

5. The backlighting system of claim 4, wherein, The free-form surfaces of the free-form lenses are polynomial aspheric surfaces or even aspheric surfaces. When the coefficient of the odd power term in the formula of the free-form surface of the polynomial aspheric surface is 0, the free-form surface is an even aspheric surface. Wherein, z represents the free-form surface height, c is the curvature, that is, the reciprocal of the radius, k is the conic coefficient, α1, α2, α3, α4, α5, α6, α7, α8, …, α 16 are aspherical coefficients, and r is the diameter of the free-form surface; or, The Fresnel lens is arranged above the free-form lens, and comprises a plane without microstructures and a convex Fresnel surface.

6. The backlighting system of claim 1, wherein, The distance between the Fresnel lens and the free-form lens is 2-40 mm, and the distance between the Fresnel lens and the LCD screen is 60-120 mm. The height of the Fresnel lens is lower than the lowest point of the LED screen. The LCD screen is arranged above the Fresnel lens, the reference angle of the LCD screen forms an angle of 15° or 20° with the horizontal plane, and the LCD screen can change within a range of 10°-30° with the horizontal plane.

7. The backlighting system of claim 1, wherein, The head-up display device comprises the backlight illumination system according to any one of claims 1-7.

8. A head-up display device, characterized by comprising: The motor vehicle comprises the backlight illumination system according to any one of claims 1-7 and / or the head-up display device according to claim 8.

9. Motor vehicle, characterized in that ​

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