LCOS optical illumination system for AR-HUD projection unit

Abstract

The invention discloses an LCOS optical illumination system for an AR-HUD projection unit, and belongs to the field of photoelectric illumination and display technologies. The system comprises an illumination light source, a collimating lens, a fly-eye lens, an optical diffuser, a wavelength selective light combination element, a polarized light conversion device, a relay lens, a PBS prism and an LCOS display chip. The illumination light source is a three-color LED light source and is composed of a red light LED, a green light LED and a blue light LED. After red primary light, green primary light and blue primary light are collimated by the collimation system, the light parallelism is optimized, the collimated light sequentially passes through the light diffusion element to optimize the light field uniformity and the fly-eye lens to eliminate the non-uniform illumination, then is unified into a single linear polarization state by the polarized light converter, is shaped by the relay system and keeps the light beam transmission quality, and finally is transmitted to the light source. And polarization state separation and light combination are realized through the PBS prism, and finally, the light is accurately coupled to the LCOS display chip, so that high-efficiency polarization state matching and imaging quality optimization are completed. According to the HUD-PGU system, the illumination brightness of the whole system is improved, the color reducibility of the system is improved, the illumination uniformity of system imaging is improved, the light energy utilization rate of the system is improved, meanwhile, the size of the HUD-PGU is reduced, and the manufacturing cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of optical technology and relates to the field of optoelectronic lighting and display technology, and specifically relates to an LCOS optical lighting system for an AR-HUD projection unit. Background Art

[0002] With the rapid development of automotive electronics, augmented reality head-up displays (AR-HUD), a core component for interactive vehicle information in intelligent cockpits, are placing increasingly stringent demands on the optical systems of their core projection units (HUD-PGUs). Traditional HUD projection systems often use gas discharge lamps as their light source. While these systems offer high brightness, they suffer from inherent drawbacks such as high energy consumption, significant startup delays, and a short lifespan. These lamps are particularly difficult to meet the demands of in-vehicle environments for miniaturization and rapid response. In recent years, with the advancement of micro-projection technology, LED solid-state light sources have gradually been applied to HUDs, but their implementation still faces significant technical bottlenecks.

[0003] While projection solutions using DLP (digital light processing) chips can achieve high-resolution displays, their complex micromirror array structure results in a bulky optical system and requires a high-speed color wheel to achieve color display. This not only increases system power consumption and mechanical complexity, but also makes it difficult to adapt to the ultra-thin structure required for AR-HUD installation. While micro-projection systems based on LCOS (liquid crystal on silicon) technology offer the advantages of high light efficiency and compactness, existing technologies still have key flaws: some solutions use a compound eye lens array for light homogenization, significantly increasing the optical path length; others introduce light rods or light cone homogenization devices in the relay optical path, which improves light field uniformity but makes it difficult to reduce the overall optical system thickness to less than 50mm, failing to meet the stringent space utilization standards of the next-generation HUD.

[0004] It is worth noting that although the existing LCOS projection solution using white light LED has achieved system miniaturization through the front light path uniformity technology, it has two core performance defects due to the spectral characteristics of white light: First, the white light LED causes a light energy loss of more than 60% when passing through the color filter, making it difficult for the projection brightness to exceed the 2000 lumen threshold, and the vehicle visibility is significantly reduced under strong ambient light; second, there is a spectral mismatch between the wide-spectrum white light and the narrow-band color filtering characteristics of the LCOS display chip (19), resulting in a color gamut coverage rate of less than 75% of the NTSC standard, seriously affecting the color reproduction accuracy of traffic warning information. In addition, the edge light effect attenuation problem of the traditional uniformity structure will further aggravate the brightness unevenness at the edge of the image, which poses a safety hazard to AR-HUDs that need to accurately project road marking information. Summary of the Invention

[0005] In order to improve the problems existing in the above-mentioned prior art, the present invention provides an LCOS optical illumination system for an AR-HUD projection unit, which optimizes the structure of the projection illumination optical system, reduces the system volume, improves the system light energy utilization rate, and reduces the design difficulty and manufacturing cost.

[0006] The technical solution adopted in the present invention is:

[0007] A LCOS optical lighting system for an AR-HUD projection unit is characterized in that the system lighting light source adopts a three-color LED light source, which is composed of a blue light LED (8a), a red light LED (8b), and a green light LED (8c); the red, green, and blue light passes through a collimation system, a light combining system, an optical diffuser (12), a light homogenization system, a polarization light conversion system, and a relay system, and is incident on an LCOS display chip (19).

[0008] In order to achieve the above-mentioned object, the present invention provides an LCOS optical illumination system for an AR-HUD projection unit, which comprises an illumination light source (8), a collimation system, a wavelength selective light combining element, an optical diffuser (12), a fly-eye lens (13), a polarization light conversion system, a relay system, a PBS prism (17), and an LCOS display chip (19). The illumination light source adopts a three-color LED light source, which is composed of a blue light LED (8a), a red light LED (8b), and a green light LED (8c); the collimation system is composed of a first collimating lens (9) and a second collimating lens (10); the light homogenizing device is a fly-eye lens (13); the light combining device includes a first dichroic mirror (11a) and a second dichroic mirror (11b); the relay system is composed of a first relay lens (15a) and a second relay lens (15b); the red, green, and blue light first passes through the collimation system and is collimated by the two collimating lenses, and the light emitted by the large divergence angle light source tends to be parallel. Subsequently, the collimated three-color light is selectively combined by the first dichroic mirror (11a) and the second dichroic mirror (11b) to form white light. The light after the light combination process will first pass through the optical diffuser (12) and then be irradiated on the compound eye lens (13). The optical diffuser (12) homogenizes the light after the three-color light combination, so that the light more evenly covers each micro lens of the compound eye lens (13). The compound eye lens (13) performs multi-directional transmission on this basis, further improving the utilization rate of light and making the distribution of light more uniform. The light after the light uniformization process is then unified into a single linear polarization state by the polarization converter (14). After the relay mirror system shapes the light beam and maintains the light beam transmission quality, the polarization state separation and light combination are achieved through the PBS prism (17), and finally accurately coupled to the LCOS display chip (19).

[0009] 1) The three-color light sources of the blue light LED (8a), the red light LED (8b), and the green light LED (8c) adopt three light paths, which are combined into one light path through a light combining device, wherein the blue light LED (8a) is in a horizontal direction, and the red light LED (8b) and the green light LED (8c) have an angle of 90° with the horizontal direction, and the light paths of the red light LED and the green light LED are parallel to each other.

[0010] 2) The collimation system is designed with a double lens for the LED light source. The collimation system includes two collimating lenses, the first lens is a spherical lens, and the second lens is an even-order aspherical lens.

[0011] 3) The optical diffuser (12) is an optical element having a microscopic rough structure or a regular pattern on its surface.

[0012] 4) The light homogenizing device is a fly-eye lens (13).

[0013] 5) The light combining device is a dichroic mirror, which is a glass plate coated with a dichroic film and has the processing characteristics of selective transmission and reflection of incident light.

[0014] 6) The polarization converter (14) is formed by gluing together a plurality of strip prisms and a half-wave plate, which divides the plurality of light beams into P-polarized light and S-polarized light. The P-polarized light is then converted into S-polarized light by the half-wave plate of the polarization converter (14).

[0015] 7) The first relay lens (15a) and the second relay lens (15b) of the relay system are not in the same horizontal direction. After the light passes through the first relay lens (15a), the light is deflected 90 degrees by the reflector (16) and hits the second relay lens (15b), thereby shortening the optical path length.

[0016] The LCOS optical illumination system for an AR-HUD projection unit of the present invention has the following advantages over the prior art:

[0017] 1. The present invention provides an LCOS optical illumination system for an AR-HUD projection unit, which adopts red, green, and blue LED light sources for illumination, and uses a light combining device and a polarization light conversion device to process the light emitted by the light source, thereby increasing the brightness of the PGU and improving color reproduction.

[0018] 2. The present invention provides an LCOS optical illumination system for an AR-HUD projection unit. The collimation system used in the present invention adopts a dual-lens design for the LED light source, which improves the collimation of the light and ensures the brightness of the lighting. At the same time, the two collimating lenses adopt a compact design, which ensures that the collimation effect remains unchanged while reducing the volume of the system.

[0019] 3. The present invention provides an LCOS optical illumination system for an AR-HUD projection unit. The optical diffuser (12) used is an optical device having a microscopic rough structure or a regular pattern on the surface. The optical diffuser (12) converts the concentrated light source into uniformly distributed surface light, so that the light more evenly covers each tiny lens of the compound eye lens (13). On this basis, the compound eye lens (13) performs multi-directional transmission, further improving the utilization rate of light and making the distribution of light more uniform.

[0020] 4. The present invention provides an LCOS optical illumination system for an AR-HUD projection unit, wherein the light homogenizing device used is a compound eye lens (13), thereby obtaining better illumination spot uniformity.

[0021] 5. The present invention provides an LCOS optical illumination system for an AR-HUD projection unit. The polarization converter (14) used is formed by gluing together multiple strip prisms and a half-wave plate. The system divides multiple light beams into P-polarized light and S-polarized light. The P-polarized light is then converted into S-polarized light by the half-wave plate of the polarization converter (14). This system can improve light utilization and thus improve the quality of optical imaging.

[0022] 6. The present invention provides an LCOS optical illumination system for an AR-HUD projection unit. The position of each optical component and the optical path structure are rationally designed for AR-HUD. Therefore, the system has the advantages of small system size, high light energy utilization, low manufacturing cost, and simple assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly express the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 This is a schematic diagram of the optical structure principle of AR-HUD;

[0025] Figure 2 This is a schematic diagram of the optical path of an LCOS optical illumination system for an AR-HUD projection unit according to an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the structure of a compound eye homogenization system of an LCOS optical illumination system for an AR-HUD projection unit according to an embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram of the structure of a relay system of an LCOS optical illumination system for an AR-HUD projection unit according to an embodiment of the present invention;

[0028] Figure 5 This is a schematic diagram of the illumination distribution of an LCOS optical illumination system for an AR-HUD projection unit according to an embodiment of the present invention.

[0029] Reference numerals:

[0030] 1-H-FOV; 2-V-FOV; 3-windshield; 4-free-form surface mirror; 5-reflector; 6-PGU; 7-human eye; 8a-blue LED light source; 8b-red LED light source; 8c-green LED light source; 9-first collimating lens; 10-second collimating lens; 11a-first dichroic mirror; 11b-second dichroic mirror; 12-optical diffuser; 13-fly-eye lens; 14-polarization converter (14); 15a-first relay lens; 15b-second relay lens; 16-reflector; 17-PBS prism; 18-LCOS display chip protection glass; 19-LCOS display chip; 20-imaging objective lens; 21-collimated light; 22-uniform light; 23-light source. DETAILED DESCRIPTION

[0031] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0032] In the description of the present invention, it should be noted that the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," etc., etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0033] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0034] An embodiment of the present invention provides an LCOS optical illumination system for an AR-HUD projection unit, which can be applied to automotive AR-HUD applications.

[0035] like Figure 1Figure 2 shows a schematic diagram of the AR-HUD optical structure. The AR-HUD system consists of a picture generation unit (PGU), a reflector, a free-form mirror, a windshield, and the human eye. The PGU generates the original image, the reflector folds the optical path, the free-form mirror optimizes the optical path and corrects aberrations, and the windshield reflects the resulting virtual image to the human eye. These components work together to achieve a deeply integrated display of navigation information and the real scene.

[0036] like Figure 2 FIG. 1 is a schematic diagram of an optical path of an LCOS optical illumination system for an AR-HUD projection unit according to an embodiment of the present invention. The system comprises an illumination light source, a collimation system, an optical diffuser (12), a light homogenizing device, a light combining device, a polarization converter (14), a relay system, a PBS prism (17), and an LCOS display chip (19).

[0037] Specifically, the illumination light source adopts a three-color LED light source, which is composed of a blue light LED (8a), a red light LED (8b), and a green light LED (8c); the collimation system is composed of a first collimating lens (9) and a second collimating lens (10); the light homogenizing device is a compound eye lens (13); the light combining device includes a first dichroic mirror (11a) and a second dichroic mirror (11b); the polarization converter (14) is formed by gluing multiple strip prisms and 1 / 2 wave plates, and divides multiple fine light beams into P-polarized light and S-polarized light; the P-polarized light is converted into S-polarized light through the 1 / 2 wave plate of the polarization converter (14); and the relay system is composed of a first relay lens (15a) and a second relay lens (15b). The red, green and blue LED lamp beads emit light with a large divergence angle. The light first passes through the first collimating lens (9) to collimate the light for the first time, reducing its divergence angle. Then, the light after the first collimation passes through the second collimating lens (10) for the second collimation. The light after the second collimation tends to be parallel. The collimated light passes through the first dichroic mirror (11a) and the second dichroic mirror (11b) to combine the light. The dichroic mirror selectively transmits and reflects the light passing through. The combined light first passes through the optical diffuser (12) and then irradiates the compound eye lens. On the mirror (13), the optical diffuser (12) homogenizes the light after the light combination, so that the light more evenly covers each tiny lens of the compound eye lens (13). The compound eye lens (13) performs multi-directional transmission on this basis, further improving the utilization rate of light and making the distribution of light more uniform. The light after the light homogenization treatment is then unified into a single linear polarization state by the polarization converter (14). After the relay mirror system shapes the light beam and maintains the light beam transmission quality, the polarization state separation and light combination are realized by the PBS prism (17), and finally accurately coupled to the LCOS display chip (19).

[0038] like Figure 3The figure shows a schematic diagram of the structure of a compound eye homogenization system of an LCOS optical illumination system for an AR-HUD projection unit according to an embodiment of the present invention. The collimated light is homogenized by a compound eye lens (13). The integrated compound eye lens (13) is improved based on the Köhler illumination principle. First, the collimated light enters the first row of compound eye lenses (13) and is precisely divided into multiple fine light beams. Subsequently, these fine light beams enter the second row of compound eye lenses (13) and overlap to form images, ensuring that every point on the illumination surface can receive uniform illumination from all points of the light source. Finally, through the superposition effect of the light spots, the non-uniformity of the light source is effectively compensated, and a highly uniform and regularly shaped light spot is finally output.

[0039] like Figure 4 The figure shows a schematic diagram of the structure of a relay system of an LCOS optical illumination system for an AR-HUD projection unit according to an embodiment of the present invention. The relay system, as a core optical component, is composed of two relay lenses. Due to the problem of space utilization, in the system of the present invention, the two relay lenses of the relay system are not in the same horizontal direction. After the light passes through the first relay lens (15a), the light is deflected 90 degrees by a reflector (16) and hits the second relay lens (15b), thereby shortening the optical path length.

[0040] like Figure 5 The figure shows a schematic diagram of the illumination distribution of an LCOS optical illumination system for an AR-HUD projection unit according to an embodiment of the present invention. The rectangular light spot projected on the LCOS display chip (19) by the LCOS optical illumination system for an AR-HUD projection unit provided by the present invention has good uniformity. The illumination margin is also relatively sufficient. The size of the screen of the LCOS display chip (19) used in the system is 8.64*4.86mm. 2 The actual measurement of the light spot size produced by the lighting system is 9*5.2mm 2 Compared with the size of the LCOS display chip (19), the margin is sufficient, and the margin is evenly distributed around the LCOS display chip (19).

[0041] An LCOS optical illumination system for an AR-HUD projection unit according to an embodiment of the present invention has the following effects:

[0042] The embodiment of the present invention provides a stable and small-sized LCOS optical lighting system solution for an automotive AR-HUD projection unit. The system uses red, green, and blue LED light sources for illumination, and uses a light combining device and a polarization light conversion device to process the light emitted by the light source, thereby increasing the brightness of the PGU and improving the color reproduction. The collimation system uses a double lens design for the LED light source to improve the collimation of the light and ensure the brightness of the illumination. At the same time, the two collimating lenses use a compact design to ensure that the collimation effect remains unchanged while reducing the volume of the system. The polarization light converter (14) used is composed of multiple strip prisms and 1 / 2 wave plates glued together, which divides multiple light beams into P polarized light and S polarized light. The P polarized light is then converted into S polarized light through the 1 / 2 wave plate of the polarization light converter (14). It can improve the utilization rate of light, thereby improving the quality of optical imaging. In addition, the position of each optical device and the optical path structure are reasonably designed for AR-HUD, so that the system has the advantages of small system volume, high light energy utilization, low manufacturing cost, and simple assembly.

[0043] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An LCOS optical illumination system for an AR-HUD projection unit, characterized in that: The system comprises an illumination light source (8), a collimation system, a wavelength selective light combining element, an optical diffuser (12), a fly-eye lens (13), a polarization light conversion system, a relay system, a PBS prism (17) and an LCOS display chip (19). The illumination light source adopts a three-color LED light source, which is composed of a blue light LED (8a), a red light LED (8b) and a green light LED (8c). The collimation system is composed of a first collimating lens (9) and a second collimating lens (10). The light homogenizing device is a fly-eye lens (13). The light combining device includes a first dichroic mirror (11a) and a second dichroic mirror (11b). The relay system is composed of a first relay lens (15a) and a second relay lens (15b). The red, green and blue light first passes through the collimation system and is collimated by the two collimating lenses. The light emitted by the large divergence angle light source tends to be parallel. Subsequently, the collimated three-color light is selectively combined by the first dichroic mirror (11a) and the second dichroic mirror (11b) to form white light. The light after the light combination process will first pass through the optical diffuser (12) and then be irradiated on the compound eye lens (13). The optical diffuser (12) homogenizes the light after the three-color light combination, so that the light more evenly covers each micro lens of the compound eye lens (13). The compound eye lens (13) performs multi-directional transmission on this basis, further improving the utilization rate of light and making the distribution of light more uniform. The light after the light uniformization process is then unified into a single linear polarization state by the polarization converter (14). After the relay mirror system shapes the light beam and maintains the light beam transmission quality, the polarization state separation and light combination are achieved through the PBS prism (17), and finally accurately coupled to the LCOS display chip (19).

2. The LCOS optical illumination system for an AR-HUD projection unit according to claim 1, characterized in that: The three-primary color LED light source adopts a three-way independent light path architecture, the blue light LED (8a) emits in a horizontal direction, the red light LED (8b) and the green light LED (8c) are respectively arranged in an orthogonal layout, and the three light beams are spatially multiplexed and synthesized through two dichroic mirror groups.

3. The LCOS optical illumination system for an AR-HUD projection unit according to claim 1, characterized in that: The collimation system adopts a dual-lens combination design for LED light sources. The first lens is a spherical lens, which is used to initially compress the light beam divergence angle; the second lens is an even-order aspheric lens, which further compresses the light beam divergence angle and provides high-quality parallel light input for subsequent optical systems.

4. The LCOS optical illumination system for an AR-HUD projection unit according to claim 1, wherein: The optical diffuser (12) is an optical element with a surface having a microscopic rough structure or a regular pattern.

5. The LCOS optical illumination system for an AR-HUD projection unit according to claim 1, wherein: The light homogenizing device is a fly-eye lens (13).

6. The LCOS optical illumination system for an AR-HUD projection unit according to claim 2, characterized in that: The polarization converter (14) is formed by gluing together a plurality of strip prisms and a half-wave plate, and divides a plurality of light beams into P-polarized light and S-polarized light. The P-polarized light is then converted into S-polarized light through the half-wave plate of the polarization converter (14).

7. The LCOS optical illumination system for an AR-HUD projection unit according to claim 2, wherein: The wavelength selective light combining element is a dichroic mirror (11a) (11b), which is a glass plate coated with a dichroic film and has the processing characteristics of selective transmission and reflection of incident light.

8. The LCOS optical illumination system for an AR-HUD projection unit according to claim 2, wherein: The first relay lens (15a) and the second relay lens (15b) of the relay system are not in the same horizontal direction. After the light passes through the first relay lens (15a), the light is deflected 90 degrees by a reflector (16) and hits the second relay lens (15b), thereby shortening the optical path and reducing the volume of the HUD-PGU.

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