Dual focal plane hud backlight optical system

Abstract

This invention discloses a dual-focal-plane HUD backlight optical system, comprising: a light source for emitting light; a lens for collimating the light emitted from the light source; a homogenizing lens for homogenizing the collimated incident light to ensure the uniformity of the virtual image plane; a freeform surface mirror for coupling the collimated and homogenized light into the imaging optical system; and an image source, wherein the collimated and homogenized light is modulated by the freeform surface mirror and coupled to the image source in a predetermined beam form, achieving uniform illumination requirements for both near and far focal planes. This invention achieves high uniformity illumination for both near and far focal planes, while sharing a single optical system for both backlighting, reducing cost and assembly difficulty. Furthermore, the system is insensitive to the size ratio of the near-focal and far-focal usage areas, allowing for adjustments to the ratio as needed.

Description

Technical Field

[0001] This utility model belongs to the field of HUD technology, specifically relating to a dual-focal-plane HUD backlight optical system. Background Technology

[0002] Most existing HUDs (Head-up Displays) only display information such as vehicle speed and navigation on a single focal plane with a fixed focal length. Because there is only a single focal plane at a fixed distance, prolonged use can lead to eye fatigue and dizziness. At the same time, the displayed image lacks a realistic sense of depth due to the single focal plane display. The development of HUDs will gradually transition to dual-focal-plane HUDs. Two focal planes at different distances can alleviate eye fatigue caused by prolonged use. This requires a matching backlight system for dual-focal-plane HUDs to achieve a highly uniform display and improve the comfort of using the HUD. However, dual-focal-plane HUDs require a separate backlight optical system for illumination. Two backlight optical systems will increase the overall cost of the HUD, which is not conducive to the popularization of dual-focal-plane HUDs. Utility Model Content

[0003] (1) Technical problems to be solved

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a dual-focal-area HUD backlight optical system, which aims to solve the problem that existing dual-focal-area HUDs require separate backlight optical systems for illumination, and that two backlight optical systems increase the overall cost of the HUD, hindering the widespread adoption of dual-focal-area HUDs.

[0005] (2) Technical solution

[0006] To solve the above-mentioned technical problems, this utility model provides a dual-focal-plane HUD backlight optical system, comprising:

[0007] A light source, which is used to emit light;

[0008] A lens; the lens is used to collimate the light emitted from the light source;

[0009] A homogenizing lens is used to homogenize collimated incident light rays to ensure the uniformity of the virtual image surface.

[0010] A freeform surface mirror, which is used to couple collimated and homogenized light rays into an imaging optical system;

[0011] The collimated and uniform light rays are modulated by a freeform surface mirror and coupled to the image source in a predetermined beam form to achieve uniform illumination requirements for both near and far focus.

[0012] Preferably, the lens collimates large-angle light emitted from the light source using total internal reflection, and the lens collimates small-angle light emitted from the light source using refraction.

[0013] Furthermore, the homogenizing lens can be a microarray lens.

[0014] Furthermore, the image source includes a near-focus usage area and a far-focus usage area, the sizes of which are changed via UI display.

[0015] Furthermore, it also includes a freeform lens, which is used to deflect the direction of light reflected by the freeform mirror, so as to better couple it to the imaging system.

[0016] Furthermore, the freeform surface mirror is divided into a first small freeform surface mirror for the far focal plane and a second small freeform surface mirror for the near focal plane.

[0017] Beneficial effects

[0018] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0019] The dual-focal-plane HUD backlight optical system of this invention can achieve high uniformity illumination of both near and far focal planes. At the same time, the backlights of near and far focal planes share a single optical system, which reduces costs and assembly difficulty, providing favorable conditions for the popularization of HUDs. The system is not sensitive to the size ratio of the near-focal and far-focal usage areas, and the ratio of the near-focal and far-focal usage areas can be changed according to needs without redesigning the backlight optical system. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the dual-focal-plane HUD backlight optical system of this utility model.

[0021] Figure 2 This is a schematic diagram showing the direction of light rays deflected by the freeform surface lens of this utility model and reflected by the freeform surface mirror.

[0022] Figure 3 This is a schematic diagram of the freeform surface reflector of this utility model, which is divided into a first small freeform surface reflector and a second small freeform surface reflector.

[0023] Figure 4 This is a schematic diagram illustrating a specific application example of this utility model.

[0024] The labels in the attached diagram are as follows: 1. Light source; 2. Lens; 3. Uniform lens; 4. Freeform surface mirror; 5. Image source; 6. Freeform surface lens; 41. First small freeform surface mirror; 42. Second small freeform surface mirror; 51. Near-focus area; 52. Far-focus area. Detailed Implementation

[0025] This specific embodiment is a dual-focal-plane HUD backlight optical system, and its structural schematic diagram is shown below. Figures 1-4 As shown, the system includes a light source 1, a lens 2, a homogenizing lens 3, a freeform surface mirror 4, and an image source 5. The light source 1 is used to emit light; the lens 2 is used to collimate the light emitted by the light source 1; the homogenizing lens 3 is used to homogenize the collimated incident light to ensure the uniformity of the virtual image surface; the freeform surface mirror 4 is used to couple the collimated and homogenized light into the imaging optical system; the collimated and homogenized light is modulated by the freeform surface mirror 4 and coupled to the image source 5 in a predetermined beam form to achieve the uniform illumination requirements for both near and far focus.

[0026] In some embodiments, lens 2 collimates the large-angle light emitted by light source 1 using total internal reflection, and collimates the small-angle light emitted by light source 1 using refraction. After the light is collimated by lens 2, the directionality of the light beam is greatly improved, which facilitates the subsequent control of the light by lens 2. Lens 2 collimates the large-angle light using total internal reflection without Fresnel loss, thereby improving the utilization rate of light energy. The deflection of light by lens 2 satisfies Snell's law.

[0027] Fresnel loss is a phenomenon in optical systems where light is reflected and refracted as it travels from one medium to another. This reflection at the surface of a lens results in a loss of light energy, which is known as Fresnel loss.

[0028] Snell's Law states that when light travels obliquely from one medium into another, refraction occurs at the interface. The sine of the angle of incidence is proportional to the sine of the angle of refraction. When lens 2 performs operations such as refraction and collimation on the light, the deflection of the light by lens 2 satisfies Snell's Law.

[0029] In some embodiments, the uniform light lens 3 can be a microlens array, which has strong local control over light, improves the uniform light effect, and ensures the uniformity of the virtual image surface.

[0030] In some embodiments, image source 5 includes a near-focus usage area 51 and a far-focus usage area 52, the sizes of which are changed via UI display.

[0031] In some embodiments, the collimated and homogenized light rays are modulated by the freeform surface mirror 4. The light rays passing through the freeform surface mirror 4 (i.e., beam modulation) need to satisfy Snell's law and be coupled to the image source 5 in a predetermined beam form to achieve uniform illumination requirements for both near and far focal points. The expression for the freeform surface mirror 4 can be expressed using an XY polynomial:

[0032] ;

[0033] Where z is the vector height, C is the radius of curvature, k is a quadratic constant, and r is the radius vector. The coefficients of the polynomial, the first term The second term is the basis term for the freeform surface. As a freeform surface, it offers greater freedom compared to traditional spherical and aspherical lenses, enabling precise control of light and achieving higher uniformity.

[0034] In some embodiments, if the angle between the light rays required for near and far focus and the normal of the image source 5 is inconsistent, a freeform lens 6 can be introduced to further deflect the direction of the light rays reflected by the freeform mirror 4, thereby better coupling them with the imaging system. Figure 2 As shown, a freeform lens 6 is introduced at the telephoto image source. The position of the freeform lens 6 is not limited to the telephoto use area 52, but can also be in the near-focus use area 51.

[0035] In some embodiments, the freeform surface mirror 4 is divided into a first small freeform surface mirror 41 for the far focal plane and a second small freeform surface mirror 42 for the near focal plane, i.e. Figure 3 As shown, once the required light angle is determined, if the angle between the light rays required for the near and far focal planes and the normal of the image source 5 is inconsistent, the freeform mirror 4 can be transformed into two smaller freeform mirrors, namely a first small freeform mirror 41 for the far focal plane and a second small freeform mirror 42 for the near focal plane. The direction of the light rays can be changed by tilting the first small freeform mirror 41 or the second small freeform mirror 42, so as to better couple them to the imaging system.

[0036] Specific application examples

[0037] like Figure 4 The diagram shows a specific implementation example. When the near-focus area 51 is reduced, there is no need to change the backlight optical system. Only the display area distribution of the image source 5 needs to be changed through the UI display, which makes the backlight optical system very versatile.

[0038] In summary, the dual-focal-plane HUD backlight optical system of this invention can achieve high uniformity illumination of both near and far focal planes. At the same time, the backlights of both near and far focal planes share a single optical system, reducing costs and assembly difficulty, and providing favorable conditions for the popularization of HUDs. Furthermore, the system is not sensitive to the size ratio of the near-focal area 51 and the far-focal area 52, and the ratio of the near-focal area 51 and the far-focal area 52 can be changed according to requirements without redesigning the backlight optical system.

[0039] All technical features in this embodiment can be freely combined according to actual needs.

[0040] The above embodiments are preferred implementations of this utility model. In addition, this utility model can also be implemented in other ways. Any obvious substitutions without departing from the concept of this technical solution are within the protection scope of this utility model.

Claims

1. A dual-focal-plane HUD backlight optical system, characterized in that: include: Light source (1), the light source (1) is used to emit light; Lens (2); the lens (2) is used to collimate the light emitted by the light source (1); The uniform light lens (3) is used to uniformly light the collimated incident light to ensure the uniformity of the virtual image surface. Freeform surface mirror (4), the freeform surface mirror (4) is used to couple collimated and uniform light rays into the imaging optical system; The collimated and uniform light rays are modulated by the freeform surface mirror (4) and coupled to the image source (5) in a predetermined beam form to achieve uniform illumination requirements for both far-focus and near-focus.

2. The bifocal HUD backlight optical system of claim 1, wherein, The lens (2) collimates the large-angle light emitted by the light source (1) using total internal reflection, and the lens (2) collimates the small-angle light emitted by the light source (1) using refraction.

3. The bifocal HUD backlight optical system of claim 1, wherein, The homogenizing lens (3) can be a microarray lens.

4. The bifocal HUD backlight optical system of claim 1, wherein, The image source (5) includes a near-focus usage area (51) and a far-focus usage area (52), the size of which is changed by the UI display.

5. The bifocal HUD backlight optical system of claim 1, wherein, It also includes a freeform lens (6), which is used to deflect the direction of light reflected by the freeform mirror (4) so ​​as to better couple the imaging system.

6. The bifocal HUD backlight optical system of claim 1, wherein, The freeform surface mirror (4) is divided into a first small freeform surface mirror (41) for the far focal plane and a second small freeform surface mirror (42) for the near focal plane.

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