Polarization conversion element, image generation unit, head-up display system, and vehicle

Abstract

The invention discloses a polarization conversion element, an image generation unit, a head-up display system and a vehicle. The polarization conversion element comprises a first prism, a first polarization beam splitting element, a first phase compensation element and a second prism which are arranged in sequence. The polarization conversion element provided by the invention is simple in manufacturing process, can reduce the manufacturing cost, is small in dislocation tolerance, can reduce the precision requirement of a machining process, reduces the sensitivity of parts, and effectively improves the polarization conversion efficiency, thereby improving the light-emitting energy of the PGU, and improving the light-emitting efficiency of the PGU.

Description

Technical Field

[0001] Embodiments of the present application relate to the technical field of optical components, and in particular, to a polarization conversion element, an image generation unit, a head-up display system, and a vehicle. Background Art

[0002] In recent years, with the development of automotive intelligence, head-up display systems (HUDs) have been increasingly widely used in automobiles. An HUD mainly consists of a picture generation unit (PGU) and optical elements. Liquid Crystal On Silicon (LCOS) chips have the advantages of high resolution, small size, power saving, and mature manufacturing technology, and are currently the mainstream technology adopted by PGU in automotive HUDs.

[0003] Since LCOS chips can only convert the polarization state of linearly polarized light and cannot achieve this function for natural light, a polarization beam splitter (PBS) is usually placed in front of the LCOS chip to purify the polarization state of the incident light. Therefore, at least half of the light emitted from the light source in the PGU is wasted. Considering other losses, the utilization rate of the light source in the PGU is usually low. To improve the utilization rate of the light source in the PGU, a polarization conversion element is usually added to the PGU to improve the purity of the polarization state, thereby increasing the light output energy. However, the existing polarization conversion elements have complex manufacturing processes, high processing costs, high requirements for processing accuracy, and high sensitivity of parts, which are extremely likely to cause an increase in the tolerance of the polarization conversion element, resulting in a low polarization conversion efficiency and being unable to effectively improve the light output energy of the PGU, making the light output efficiency of the PGU low. Summary of the Invention

[0004] A polarization conversion element, an image generation unit, a head-up display system, and a vehicle provided by the embodiments of the present application can solve or partially solve the above-mentioned deficiencies in the prior art or other deficiencies in the prior art.

[0005] According to a first aspect of the present application, a polarization conversion element is provided, which includes a first prism, a first polarization splitting element, a first phase compensation element, and a second prism arranged in sequence.

[0006] In an embodiment of the present application, the first polarization splitting element allows P-polarized light to pass through and reflects S-polarized light; the first phase compensation element converts P-polarized light into S-polarized light.

[0007] In an embodiment of the present application, the first polarization beam splitting element transmits S-polarized light and reflects P-polarized light; the first phase compensation element converts S-polarized light into P-polarized light.

[0008] In an embodiment of the present application, when used with the compound eye lens, the width d of the polarization conversion element and the aperture d0 of the compound eye unit in the compound eye lens satisfy: 0.8 ≤ d0 / d ≤ 1.2.

[0009] In an embodiment of the present application, the width D1 of the first prism, the width D2 of the first polarization beam splitting element, and the width D3 of the first phase compensation element satisfy: 2 ≤ (D1 + D2) / D3 ≤ 10.

[0010] In an embodiment of the present application, the width D1 of the first prism and the width D4 of the second prism satisfy: 0.8 ≤ D1 / D4 ≤ 1.2.

[0011] In an embodiment of the present application, the first prism has an incident light surface, the first prism and the second prism have an outgoing light surface, and the incident light surface is parallel to the outgoing light surface; the first prism and the second prism also have a first inclined surface and a second inclined surface, and the first inclined surface is parallel to the second inclined surface; a reflective film is provided on the first inclined surface of the first prism, and the first polarization beam splitting element and the first phase compensation element are arranged between the second inclined surface of the first prism and the first inclined surface of the second prism.

[0012] In an embodiment of the present application, the first prism, the first polarization beam splitting element, and the first phase compensation element are arranged on one side of the second prism; the polarization conversion element further includes: a second polarization beam splitting element, a third prism, a third polarization beam splitting element, and a second phase compensation element, and the second polarization beam splitting element, the third prism, the third polarization beam splitting element, and the second phase compensation element are sequentially arranged on the other side of the second prism.

[0013] In an embodiment of the present application, the first polarization beam splitting element transmits P-polarized light and reflects S-polarized light; the first phase compensation element converts P-polarized light into S-polarized light; the second polarization beam splitting element transmits S-polarized light and reflects P-polarized light; the third polarization beam splitting element transmits P-polarized light and reflects S-polarized light; the second phase compensation element converts P-polarized light into S-polarized light.

[0014] In an embodiment of the present application, the first polarization beam splitting element transmits S-polarized light and reflects P-polarized light; the first phase compensation element converts S-polarized light into P-polarized light; the second polarization beam splitting element transmits P-polarized light and reflects S-polarized light; the third polarization beam splitting element transmits S-polarized light and reflects P-polarized light; the second phase compensation element converts S-polarized light into P-polarized light.

[0015] In an embodiment of the present application, when used with the compound eye lens, the aperture d0 of the compound eye unit in the compound eye lens and the thickness H0 of the compound eye lens satisfy: 5 ≤ H0 / d0 ≤ 20.

[0016] In an embodiment of the present application, the first prism, the second prism, and the third lens all have an incident light surface, the first prism, the second prism, and the third lens all have an exit light surface, and the incident light surface is parallel to the exit light surface; the first prism, the second prism, and the third lens also have a first inclined surface and a second inclined surface, and the first inclined surface is parallel to the second inclined surface; a fourth polarization beam splitting element is provided on the first inclined surface of the first prism, and the fourth polarization beam splitting element has the same transmission and reflection properties for polarized light as the first polarization beam splitting element; the first polarization beam splitting element and the first phase compensation element are arranged between the second inclined surface of the first prism and the first inclined surface of the second prism, the second polarization beam splitting element is arranged between the second inclined surface of the second prism and the first inclined surface of the third prism, and the third polarization beam splitting element and the second phase compensation element are arranged on the second inclined surface of the third prism.

[0017] In an embodiment of the present application, the width d of the polarization conversion element satisfies: 0.2 mm ≤ d ≤ 2 mm; the light flux W1 of the effective polarized light before the polarization conversion element, the light flux W2 of the effective polarized light after the polarization conversion element, and the width d of the polarization conversion element satisfy: 0.35 ≤ W2 / W1*d ≤ 5.

[0018] In an embodiment of the present application, the conversion efficiency W2 / W1 of the polarization conversion element satisfies: W2 / W1 ≥ 55%.

[0019] In an embodiment of the present application, the angle θ between the first inclined surface and the incident light surface satisfies: 30° ≤ θ ≤ 60°; the phase compensation amount of the phase compensation element is λ / 2, where λ is the working wavelength band of the phase compensation element.

[0020] In an embodiment of the present application, the sequential arrangement manners of the prism, the polarization beam splitting element, and the phase compensation element include at least one of snap-fitting, clamping, laminating, and gluing.

[0021] In an embodiment of the present application, it is characterized in that the polarization splitting element includes one of a metal wire grid polarization splitting film and a coated polarization splitting film; and / or, the phase compensation element includes a phase retardation film.

[0022] According to a second aspect of the present application, a polarization conversion assembly is provided, including: at least two polarization conversion elements arranged in sequence; wherein, each of the at least two polarization conversion elements includes: a first prism, a first polarization splitting element, a first phase compensation element, and a second prism arranged in sequence.

[0023] In an embodiment of the present application, the first polarization splitting element transmits P-polarized light and reflects S-polarized light; the first phase compensation element converts P-polarized light into S-polarized light.

[0024] In an embodiment of the present application, the first polarization splitting element transmits S-polarized light and reflects P-polarized light; the first phase compensation element converts S-polarized light into P-polarized light.

[0025] In an embodiment of the present application, when used with a compound eye lens, the width d of the polarization conversion element and the aperture d0 of the compound eye unit in the compound eye lens satisfy: 0.8 ≤ d0 / d ≤ 1.2.

[0026] In an embodiment of the present application, the apertures of the compound eye units in the compound eye lens are different, and the aperture B1 of the compound eye unit located at the center of the compound eye lens and the aperture B2 of the compound eye unit located around the center satisfy: 1 ≤ B2 / B1 ≤ 2.

[0027] In an embodiment of the present application, the width of the first prism located in the middle of the polarization conversion assembly is smaller than the width of the first prisms located at both ends of the polarization conversion assembly.

[0028] In an embodiment of the present application, the width D1 of the first prism, the width D2 of the first polarization splitting element, and the width D3 of the first phase compensation element satisfy: 2 ≤ (D1 + D2) / D3 ≤ 10.

[0029] In an embodiment of the present application, the width D1 of the first prism and the width D4 of the second prism satisfy: 0.8 ≤ D1 / D4 ≤ 1.2.

[0030] In an embodiment of the present application, the first prism has an incident light surface, the first prism and the second prism have an emergent light surface, and the incident light surface is parallel to the emergent light surface; the first prism and the second prism also have a first inclined surface and a second inclined surface, and the first inclined surface is parallel to the second inclined surface; a reflective film is provided on the first inclined surface of the first prism, and the first polarization beam splitting element and the first phase compensation element are disposed between the second inclined surface of the first prism and the first inclined surface of the second prism.

[0031] In an embodiment of the present application, the first prism, the first polarization beam splitting element, and the first phase compensation element are disposed on one side of the second prism; each of the polarization conversion elements further includes: a second polarization beam splitting element, a third prism, a third polarization beam splitting element, and a second phase compensation element, and the second polarization beam splitting element, the third prism, the third polarization beam splitting element, and the second phase compensation element are sequentially disposed on the other side of the second prism.

[0032] In an embodiment of the present application, the first polarization beam splitting element transmits P-polarized light and reflects S-polarized light; the first phase compensation element converts P-polarized light into S-polarized light; the second polarization beam splitting element transmits S-polarized light and reflects P-polarized light; the third polarization beam splitting element transmits P-polarized light and reflects S-polarized light; the second phase compensation element converts P-polarized light into S-polarized light.

[0033] In an embodiment of the present application, the first polarization beam splitting element transmits S-polarized light and reflects P-polarized light; the first phase compensation element converts S-polarized light into P-polarized light; the second polarization beam splitting element transmits P-polarized light and reflects S-polarized light; the third polarization beam splitting element transmits S-polarized light and reflects P-polarized light; the second phase compensation element converts S-polarized light into P-polarized light.

[0034] In an embodiment of the present application, when used with a compound eye lens, the aperture d0 of the compound eye unit in the compound eye lens and the thickness H0 of the compound eye unit satisfy: 5 ≤ H0 / d0 ≤ 20.

[0035] In an embodiment of the present application, the widths of the prisms in the at least two polarization conversion elements are different, and the maximum width A1 of the prism and the minimum width A2 of the prism satisfy: 1 ≤ A1 / A2 ≤ 10.

[0036] In an embodiment of the present application, the width of the prism located in the middle of the polarization conversion assembly is greater than the width of the prisms located at both ends of the polarization conversion assembly.

[0037] In an embodiment of the present application, the first prism, the second prism, and the third lens each have an incident light surface, and the first prism, the second prism, and the third lens each have an emergent light surface, and the incident light surface is parallel to the emergent light surface; the first prism, the second prism, and the third lens also have a first inclined surface and a second inclined surface, and the first inclined surface is parallel to the second inclined surface; a fourth polarization beam splitting element is provided on the first inclined surface of the first prism, and the fourth polarization beam splitting element has the same transmission and reflection properties for polarized light as the first polarization beam splitting element; the first polarization beam splitting element and the first phase compensation element are arranged between the second inclined surface of the first prism and the first inclined surface of the second prism, the second polarization beam splitting element is arranged between the second inclined surface of the second prism and the first inclined surface of the third prism, and the third polarization beam splitting element and the second phase compensation element are arranged on the second inclined surface of the third prism.

[0038] In an embodiment of the present application, the width d of the polarization conversion element satisfies: 0.2 mm ≤ d ≤ 2 mm; the light flux W1 of the effective polarized light before the polarization conversion element, the light flux W2 of the effective polarized light after the polarization conversion element, and the width d of the polarization conversion element satisfy: 0.35 ≤ W2 / W1 * d ≤ 5.

[0039] In an embodiment of the present application, the conversion efficiency W2 / W1 of the polarization conversion element satisfies: W2 / W1 ≥ 55%.

[0040] In an embodiment of the present application, the included angle θ between the first inclined surface and the incident light surface satisfies: 30° ≤ θ ≤ 60°; the phase compensation amount of the phase compensation element is λ / 2, where λ is the working wavelength band of the phase compensation element.

[0041] In an embodiment of the present application, the thickness H of the polarization conversion assembly and the aperture D of the polarization conversion assembly satisfy: 5 ≤ D / H ≤ 125.

[0042] In an embodiment of the present application, the arrangement method in which the at least two polarization conversion elements are arranged in sequence includes at least one of buckling, clamping, fitting, and gluing; the arrangement method in which the prism, the polarization beam splitting element, and the phase compensation element in each polarization conversion element are arranged in sequence includes at least one of buckling, clamping, fitting, and gluing.

[0043] In an embodiment of the present application, the polarization beam splitting element includes one of a metal wire grid polarization beam splitting film and a coated polarization beam splitting film; and / or, the phase compensation element includes a phase retardation plate.

[0044] According to a third aspect of the present application, an image generation unit is provided, including: a light source system, a display chip, and the polarization conversion element described in the first aspect or the polarization conversion assembly described in the second aspect; wherein, the natural light emitted by the light source system is subjected to polarization conversion by the polarization conversion element or the polarization conversion assembly and then projected onto the display chip to generate an image.

[0045] In an embodiment of the present application, it further includes: a compound eye lens, and the compound eye lens is located between the light source system and the polarization conversion element or the polarization conversion assembly.

[0046] In an embodiment of the present application, the display chip includes an LCOS chip.

[0047] In an embodiment of the present application, it further includes: a polarization beam splitter element and a polarization element; the S-polarized light in the light projected onto the display chip passes through the polarization beam splitter element and is converted into P-polarized light by the display chip to generate an image; the P-polarized light emitted by the image is reflected by the polarization beam splitter element to the polarization element and passes through the polarization element.

[0048] In an embodiment of the present application, it further includes: a polarization beam splitter element and a polarization element; the P-polarized light in the light projected onto the display chip passes through the polarization beam splitter element and is converted into S-polarized light by the display chip to generate an image; the S-polarized light emitted by the image is reflected by the polarization beam splitter element to the polarization element and passes through the polarization element.

[0049] In an embodiment of the present application, the transmittance Tp of P-polarized light, the transmittance Ts of S-polarized light, the reflectance Rs of S-polarized light, and the reflectance Rp of P-polarized light of the polarization beam splitter element in the range of 45° ± 20° satisfy: Tp ≥ 85%, Ts ≤ 0.05%, Rs ≥ 80%, Rp ≤ 3%; the transmittance Ts of S-polarized light and the reflectance Rs of S-polarized light of the polarization element in the range of 0° ± 20° satisfy: Ts ≥ 85%, Rs ≤ 0.1%.

[0050] In an embodiment of the present application, the display chip includes an LCD chip.

[0051] According to a fourth aspect of the present application, a head-up display system is provided, including the image generation unit described in the third aspect.

[0052] According to a fifth aspect of the present application, a vehicle is provided, including the head-up display system described in the fourth aspect.

[0053] The polarization conversion element, image generation unit, head-up display system and vehicle provided according to the embodiments of the present application realize the conversion of polarized light by arranging a polarization beam splitter element and a phase compensation element between two prisms. The manufacturing process is simple, the manufacturing cost can be reduced, the misalignment tolerance is small, the precision requirements of the processing technology can be reduced, the sensitivity of the parts can be reduced, and the efficiency of polarization conversion can be effectively improved. Thus, the light output energy of the PGU can be increased, and the light emission efficiency of the PGU can be improved.

[0054] The content described in this part is not intended to identify the key or important features of the embodiments of the present disclosure, nor is it used to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] By reading the detailed description of the non-limiting embodiments with reference to the following drawings, other features, objectives and advantages of the present application will become more obvious. The drawings are used to better understand the solution and do not constitute a limitation to the present application. Among them:

[0056] Figure 1 is a schematic diagram of the composition structure of an image generation unit in an existing head-up display system;

[0057] Figure 2 is a schematic diagram of the composition structure of a polarization conversion element in an existing image generation unit;

[0058] Figure 3 is a schematic diagram of the composition structure of a polarization conversion element according to an embodiment of the present application;

[0059] Figure 4 is a schematic diagram of the corresponding relationship between a polarization conversion element and a fly-eye lens according to an embodiment of the present application;

[0060] Figure 5 is a schematic diagram of the working principle of a polarization conversion element according to an embodiment of the present application;

[0061] Figure 6 is a schematic diagram of the working principle of a polarization conversion element according to another embodiment of the present application;

[0062] Figure 7 is a schematic diagram of the composition structure of a polarization conversion element according to another embodiment of the present application;

[0063] Figure 8 is a schematic diagram of the working principle of a polarization conversion element according to yet another embodiment of the present application;

[0064] Figure 9 is a schematic diagram of the composition structure of an image generation unit of a polarization conversion module applying the embodiments of the present application;

[0065] Figure 10 is a schematic structural diagram of an image generation unit according to an embodiment of the present application;

[0066] Figure 11 is a schematic diagram of the corresponding relationship between a polarization conversion element and a compound eye lens according to an embodiment of the present application;

[0067] Figure 12A is a schematic diagram of the corresponding relationship between a polarization conversion element and a compound eye lens according to another embodiment of the present application;

[0068] Figure 12B is a schematic structural diagram of a polarization conversion element according to another embodiment of the present application;

[0069] Figure 13A and Figure 13B is a schematic diagram of a polarization beam splitter element according to an embodiment of the present application;

[0070] Figure 14A and Figure 14B is a schematic diagram of a polarization beam splitter element according to another embodiment of the present application;

[0071] Figure 15A and Figure 15B is a schematic structural diagram of a polarization conversion module according to two embodiments of the present application;

[0072] Figure 16 is a schematic structural diagram of an image generation unit according to another embodiment of the present application;

[0073] Figure 17A is a schematic structural diagram of a polarization conversion element according to yet another embodiment of the present application;

[0074] Figure 17B is a schematic structural diagram of an image generation unit according to yet another embodiment of the present application. Detailed implementation manners

[0075] The following makes an explanation of the exemplary embodiments of the present application in conjunction with the accompanying drawings. Various details of the embodiments of the present application are included to facilitate understanding, and they should be considered merely exemplary. Therefore, those of ordinary skill in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. Similarly, for the sake of clarity and conciseness, the description of well-known functions and structures is omitted below.

[0076] In the accompanying drawings, for the sake of clarity, the thickness, dimensions, and shape of the components have been slightly adjusted. The accompanying drawings are for illustrative purposes only and are not drawn to an exact scale. As used herein, the terms "substantially", "about", and similar terms are used as terms of approximation and not of degree, and are intended to account for the inherent deviations in measured or calculated values that would be recognized by a person of ordinary skill in the art.

[0077] It should also be understood that expressions such as "comprises", "comprising", "has", "including", and / or "containing" are open-ended and not closed-ended expressions in this specification, which means that the stated features, elements, and / or components exist, but do not exclude the existence of one or more other features, elements, components, and / or combinations thereof. In addition, when an expression such as "at least one of..." appears after a list of listed features, it modifies the entire list of features, rather than just individual elements in the list. In addition, when describing embodiments of the present application, the use of "may" means "one or more embodiments of the present application". And the term "exemplary" is intended to refer to an example or illustration.

[0078] Unless otherwise defined, all terms used herein (including engineering and scientific terms) have the same meaning as commonly understood by a person of ordinary skill in the art to which this application belongs. It should also be understood that, unless explicitly stated in this application, words defined in a commonly used dictionary should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and should not be interpreted in an idealized or overly formal sense.

[0079] It should be noted that, without conflict, the embodiments and features in the embodiments of this application may be combined with each other. In addition, unless explicitly defined or in contradiction with the context, the specific steps included in the methods described in this application do not have to be limited to the recited order, but may be executed in any order or executed in parallel.

[0080] In addition, those skilled in the art can understand that the quantities shown in the accompanying drawings and the following text of this application, such as the number of optical films, etc., are only shown for convenience of illustration, and the specific quantity can be set according to actual needs without departing from the teachings of the disclosure of this application.

[0081] In existing automotive HUDs, the LCOS chips used in PGU can only convert the polarization state of linearly polarized light and cannot perform this function for natural light. Usually, a PBS needs to be placed in front of the LCOS chip to purify the polarization state of the incident light. Therefore, at least half of the light emitted from the light source in the PGU is wasted. Considering other losses, the utilization rate of the light source in the PGU is usually low. To improve the utilization rate of the light source in the PGU, a polarization conversion element is usually added to the PGU to improve the purity of the polarization state, thereby increasing the light output energy.

[0082] Figure 1 shows a schematic diagram of the composition structure of the image generation unit in the existing head-up display system. As Figure 1 shown, the existing image generation unit mainly includes: a light source collimation and beam combination system 110, a fly-eye lens 120, a polarization conversion element 130, a relay system 140, a polarization beam splitter element 150, a phase compensation film 160, an LCOS chip 170, a polarization element 180, and an imaging lens 190. Among them, the light source in the light source collimation and beam combination system 110 can use a light-emitting diode (LED) light source or a laser diode (LD) light source. Taking the LED light source as an example, the natural light emitted by the LED includes P-polarized light and S-polarized light. After being collimated by the collimation and beam combination system, the light is then homogenized and shaped by the fly-eye lens 120. After that, the polarization conversion element 130 can convert the natural light into mostly P-polarized light and a small part of S-polarized light, which can effectively improve the utilization rate of light energy. The light emitted from the polarization conversion element 130 is beam-shaped by the relay system 140. The function of the polarization beam splitter element 150 is to transmit P-polarized light and reflect S-polarized light. Among them, the P-polarized light passes through the polarization beam splitter element 150 and is incident on the LCOS chip 170 after passing through the phase compensation film 160. The LCOS chip 170 converts the P-polarized light into S-polarized light according to the liquid crystal display principle. Due to the phase loss of the liquid crystal, the phase compensation is carried out by the phase compensation film 160. The phase-compensated S-polarized light is reflected by the polarization beam splitter element 150 to the polarization element 180. Since the polarization element 180 only allows one kind of linearly polarized light to pass through, only the S-polarized light passes through the polarization element 180, and then is projected onto the image plane through the imaging lens 190.

[0083] The existing manufacturing process of the polarization conversion element 130 is complex, which also results in a high processing cost of the polarization conversion element 130. Under the limitations of the size and thickness of the fly-eye lens 120, the size range of the polarization conversion element 130 is 0.2 mm to 1 mm. The smaller the size of the polarization conversion unit 130, the higher the conversion efficiency, and at the same time, the more complex the processing technology. Figure 2 shows a schematic diagram of the composition structure of the polarization conversion element in the existing image generation unit. As Figure 2 shown, the polarization conversion element 130 is glued together by a variety of parts. Among them, the prism 131 is glued to form the body of the polarization conversion element 130. An anti-reflection film is deposited on the plane 131a of the prism 131, and its light transmittance T'≥99.8%. A polarization beam splitting film is deposited on the glued inclined plane 131b of the prism 131, and its main function is to transmit P-polarized light and reflect S-polarized light. A 1 / 2 wave plate 132 is glued to the uppermost end of the plane 131a of the prism 131, and its main function is to convert the reflected S-polarized light into P-polarized light, so as to achieve the polarization conversion effect of the element.

[0084] However, during the actual manufacturing process, the transmittance and reflectance of the polarization beam splitting film on the glued bevel 131b are affected by the prism material and the film layer process, and the overall extinction ratio is relatively low, with its extinction ratio EX' ≤ 100:1. In this application, the extinction ratio refers to the ratio of the transmittance of P-polarized light to the transmittance of S-polarized light. Since the size of the polarization conversion element 130 is small and the 1 / 2 wave plate 132 is only attached above one prism 131, the situation of misalignment of the 1 / 2 wave plate 132 is likely to occur, causing an increase in the misalignment tolerance between the prism 131 and the 1 / 2 wave plate. The misalignment tolerance can increase from the original ±0.02 mm to ±0.1 mm, resulting in a decrease in the polarization conversion efficiency. At the same time, the tolerance generated during the processing of the size of the prism 131, such as inconsistent sizes of the prisms, will cause an increase in the matching tolerance between the polarization conversion element 130 and the compound eye lens 120, and will also cause a decrease in the polarization conversion efficiency. Therefore, the P-polarized light conversion efficiency of the existing polarization conversion element 130 is only about 40% - 50%, and the overall energy of the PGU only increases by about 30%.

[0085] To solve the above problems, an embodiment of this application provides a polarization conversion element 230.

[0086] Figure 3 The schematic composition structure diagram of the polarization conversion element 230 according to the embodiment of this application is shown. The polarization conversion element 230 according to the embodiment of this application can be applied to the PGU of the HUD for polarization light conversion. As Figure 3 shown, the polarization conversion element 230 may include: a first prism 231, a first polarization beam splitting element 232, a first phase compensation element 233, and a second prism 234 arranged in sequence.

[0087] After natural light is incident on the polarization conversion element 230 according to the embodiment of this application, the S-polarized light and P-polarized light in natural light can be split according to the different reflection and transmission performances of the first polarization beam splitting element 232 for different polarized lights, and the split S-polarized light or P-polarized light can be phase-compensated according to the phase compensation function of the first phase compensation element 233 to achieve the conversion of polarized light, that is, converting P-polarized light into S-polarized light, or converting S-polarized light into P-polarized light.

[0088] The polarization conversion element 230 according to the embodiment of the present application may be an element that converts P-polarized light into S-polarized light, or an element that converts S-polarized light into P-polarized light. When the polarization conversion element 230 is an element that converts P-polarized light into S-polarized light, the first polarization beam splitter 232 transmits P-polarized light and reflects S-polarized light, and the first phase compensation element 233 converts P-polarized light into S-polarized light. When the polarization conversion element 231 is an element that converts S-polarized light into P-polarized light, the first polarization beam splitter 232 transmits S-polarized light and reflects P-polarized light, and the first phase compensation element 233 converts S-polarized light into P-polarized light.

[0089] As Figure 3 shown, the embodiment of the present application also provides a polarization conversion assembly 2300, which includes: at least two polarization conversion elements 230, and the at least two polarization conversion elements 230 are arranged in sequence; each polarization conversion element 230 includes a first prism 231, a first polarization beam splitter 232, a first phase compensation element 233, and a second prism 234 arranged in sequence.

[0090] The polarization conversion element 230 according to the embodiment of the present application realizes the conversion of polarized light by arranging the first polarization beam splitter 232 and the first phase compensation element 233 between the first prism 231 and the second prism 234. The manufacturing process is simple, the manufacturing cost can be reduced, the misalignment tolerance is small, the precision requirements of the processing technology can be reduced, the sensitivity of the parts can be reduced, and the efficiency of polarization conversion can be effectively improved. Thus, the light output energy of the PGU can be increased, and the light emission efficiency of the PGU can be improved.

[0091] It should be noted that the embodiment of the present application does not limit the materials, shapes, refractive indices, etc. of the first prism 231 and the second prism 234 in the polarization conversion element 230. For example, the first prism 231 and the second prism 234 may be made of glass material or plastic material; the first prism 231 and the second prism 234 may be parallelogram prisms, or a combination of a parallelogram prism and a triangular prism, etc.

[0092] It should be noted that the embodiment of the present application does not limit the types and structures, etc. of the first polarization beam splitter 232 in the polarization conversion element 230. For example, the first polarization beam splitter 232 may be a metal wire grid polarization beam splitter or a coated polarization beam splitter; when the first polarization beam splitter 232 is a metal wire grid polarization beam splitter, the direction of its wire grid lines can be set according to the reflection and transmission properties of different polarized lights; when the first polarization beam splitter 232 is a coated polarization beam splitter, the material, structure, and thickness of its film layer can be set according to the reflection and transmission properties of different polarized lights.

[0093] It should be noted that the embodiments of the present application do not limit the type and phase compensation amount of the first phase compensation element 233 in the polarization conversion element 230. For example, the first phase compensation element 233 may employ a phase retardation plate, and the phase retardation amount of the phase retardation plate may be determined according to the shape of the prism and the position where the phase retardation plate is disposed on the prism, etc.

[0094] It should be noted that the embodiments of the present application do not limit the setting manner of the first prism 231, the first polarization beam splitter element 232, the first phase compensation element 233, and the second prism 234 in the polarization conversion element 230. For example, the setting manner in which the first prism 231, the first polarization beam splitter element 232, the first phase compensation element 233, and the second prism 234 are sequentially arranged in the polarization conversion element 231 may be at least one of buckling, clamping, fitting, and gluing, etc.

[0095] It should be noted that the embodiments of the present application do not limit the number of the polarization conversion elements 230 in the polarization conversion assembly 2300 and the setting manner of the polarization conversion elements 230, etc. For example, as Figure 3 shown, the number of the polarization conversion elements 230 in the polarization conversion assembly 2300 is 3. Of course, in other embodiments of the present application, the number of the polarization conversion elements 230 in the polarization conversion assembly 2300 may also be 4, 5, 7, 10, etc. The setting manner in which at least two polarization conversion elements 230 are sequentially arranged in the polarization conversion assembly 2300 may be at least one of buckling, clamping, fitting, and gluing, etc.

[0096] It should be noted that the embodiments of the present application do not limit the composition structure of the polarization conversion assembly 2300. For example, as Figure 3 shown, in addition to including 3 polarization conversion elements 230, the polarization conversion assembly 2300 may further include two triangular prisms, and the two triangular prisms are respectively disposed at both ends of the 6 polarization conversion elements 230, so that the entire polarization conversion assembly 2300 forms a rectangular structure.

[0097] In some alternative embodiments of the present application, the width D1 of the first prism 231, the width D2 of the first polarization beam splitter element 232, the width D3 of the first phase compensation element 233, and the width D4 of the second prism 234 may satisfy the conditional formula: 2 ≤ (D1 + D2) / D3 ≤ 10; the width D1 of the first prism 231 and the width D4 of the second prism 234 may satisfy the conditional formula: 0.8 ≤ D1 / D4 ≤ 1.2. As Figure 3 shown, in the polarization conversion element 230, the lengths of the first prism 231, the first polarization beam splitter element 232, the first phase compensation element 233, and the second prism 234 may be equal, that is, the first prism 231, the first polarization beam splitter element 232, the first phase compensation element 233, and the second prism 234 are alongFigure 3 The dimensions in the y direction can be equal. The widths of the first prism 231, the first polarization beam splitter element 232, the first phase compensation element 233, and the second prism 234, that is, the dimensions of the first prism 231, the first polarization beam splitter element 232, the first phase compensation element 233, and the second prism 234 along Figure 3 the x direction in the can satisfy the above conditional expression. By making the widths of the first prism 231, the first polarization beam splitter element 232, the first phase compensation element 233, and the second prism 234 in the polarization conversion element 230 satisfy the above conditional expression, the widths of the prism, the polarization beam splitter element, and the phase compensation element in the polarization conversion element 230 can be restricted, the incident light area of the polarization conversion element 230 can be increased, the light utilization rate of the polarization conversion element 230 can be improved, the polarization conversion efficiency of the polarization conversion element 230 can be effectively improved, and the light efficiency can be improved.

[0098] In some alternative embodiments of the present application, when the polarization conversion element 230 is used with a compound eye lens, the polarization conversion element 230 is disposed behind the compound eye lens, and the width d of the polarization conversion element and the aperture d0 of the compound eye unit in the compound eye lens can satisfy the conditional expression: 0.8 ≤ d0 / d ≤ 1.2. Preferably, 0.9 ≤ d0 / d ≤ 1.1, where the width d of the polarization conversion element includes the width D1 of the first prism, the width D2 of the first polarization beam splitter element 232, the width D3 of the first phase compensation element 233, and the width D4 of the second prism 234. As Figure 4 shown, the polarization conversion element 230 can be disposed behind the compound eye lens 220 during use, so that the light emitted from the compound eye lens 220 can enter the polarization conversion element 230 for polarization conversion. In order to achieve the best effect, the size of the polarization conversion unit 131 needs to correspond one-to-one with the size of the compound eye unit 221 in the compound eye lens 220, that is, the width d of the polarization conversion unit 130 needs to correspond one-to-one with the aperture d0 of the compound eye unit 221 in the compound eye lens 220, so that the natural light including P-polarized light and S-polarized light emitted from the compound eye unit 221 enters the corresponding polarization conversion unit 130 for polarization conversion, and most of the P-polarized light therein is converted into S-polarized light, or most of the S-polarized light therein is converted into P-polarized light. By making the width of the polarization conversion element and the aperture of the compound eye unit in the compound eye lens satisfy the above conditional expression, the widths of the prism, the polarization beam splitter element, and the phase compensation element in the polarization conversion element 230 can be restricted, and the polarization conversion efficiency of the polarization conversion element 230 can be improved.

[0099] In some alternative embodiments of the present application, as Figure 4As shown, the first prism 231 has an incident light surface 231a, and the first prism 231 and the second prism 234 have outgoing light surfaces 231b and 234b. The incident light surface 231a is parallel to the outgoing light surfaces 231b and 234b. The first prism 231 and the second prism 234 also have first inclined surfaces 231c and 234c and second inclined surfaces 231d and 234d. The first inclined surfaces 231c and 234c are parallel to the second inclined surfaces 231d and 234d. A reflective film is provided on the first inclined surface 231c of the first prism 231. The first polarization beam splitter element 232 and the first phase compensation element 233 are disposed between the second inclined surface 231d of the first prism 231 and the first inclined surface 234c of the second prism 234. In an alternative example, the first prism 231 and the second prism 234 are parallelogram prisms, and the incident light surface, the outgoing light surface, the first inclined surface, and the second inclined surface respectively correspond to the four sides of the parallelogram in the cross-section of the parallelogram prism.

[0100] Optionally, when the polarization conversion element 230 is an element that converts P-polarized light into S-polarized light, as Figure 5 shown, the P-polarized light in the natural light including P-polarized light and S-polarized light incident from the incident light surface 231a passes through the first polarization beam splitter element 232, and the S-polarized light is reflected by the first polarization beam splitter element 232. Among them, the P-polarized light passing through the first polarization beam splitter element 232 is converted into S-polarized light by the first phase compensation element 233 and exits from the outgoing light surface 234b of the second prism 234. The S-polarized light reflected by the first polarization beam splitter element 232 is reflected to the first inclined surface 231c of the first prism 231 and is reflected by the reflective film on the first inclined surface 231c and exits from the outgoing light surface 231b of the first prism 231.

[0101] Optionally, when the polarization conversion element 230 is an element that converts S-polarized light into P-polarized light, as Figure 6 shown, the S-polarized light in the natural light including S-polarized light and P-polarized light incident from the incident light surface 231a passes through the first polarization beam splitter element 232, and the P-polarized light is reflected by the first polarization beam splitter element 232. Among them, the S-polarized light passing through the first polarization beam splitter element 232 is converted into P-polarized light by the first phase compensation element 233 and exits from the outgoing light surface 234b of the second prism 234. The P-polarized light reflected by the first polarization beam splitter element 232 is reflected to the first inclined surface 231c of the first prism 231 and is reflected by the reflective film on the first inclined surface 231c and exits from the outgoing light surface 231b of the first prism 231.

[0102] In some alternative embodiments of the present application, as Figure 7As shown, the first prism 231, the first polarization beam splitting element 232, and the first phase compensation element 233 are disposed on one side of the second prism 234. The polarization conversion element 230 further includes: a second polarization beam splitting element 235, a third prism 236, a third polarization beam splitting element 237, and a second phase compensation element 238. The second polarization beam splitting element 235, the third prism 236, the third polarization beam splitting element 237, and the second phase compensation element 238 are sequentially disposed on the other side of the second prism 234.

[0103] After natural light is incident on the polarization conversion element 230 of the present embodiment, the S-polarized light and P-polarized light in natural light can be split according to the different reflection and transmission performances of the first polarization beam splitting element 232, the second polarization beam splitting element 235, and the third polarization beam splitting element 237 for different polarized lights. The phase compensation function of the first phase compensation element 233 and the second phase compensation element 238 can be used to perform phase compensation on the split S-polarized light or P-polarized light, realizing the conversion of polarized light, that is, converting P-polarized light into S-polarized light, or converting S-polarized light into P-polarized light.

[0104] The polarization conversion element 230 of the present embodiment can be an element that converts P-polarized light into S-polarized light, or an element that converts S-polarized light into P-polarized light. When the polarization conversion element 230 is an element that converts P-polarized light into S-polarized light, the first polarization beam splitting element 232 transmits P-polarized light and reflects S-polarized light, the first phase compensation element 233 converts P-polarized light into S-polarized light, the second polarization beam splitting element 235 transmits S-polarized light and reflects P-polarized light, the third polarization beam splitting element 237 transmits P-polarized light and reflects S-polarized light, and the second phase compensation element 238 converts P-polarized light into S-polarized light. When the polarization conversion element 231 is an element that converts S-polarized light into P-polarized light, the first polarization beam splitting element 232 transmits S-polarized light and reflects P-polarized light, the first phase compensation element 233 converts S-polarized light into P-polarized light, the second polarization beam splitting element 235 transmits P-polarized light and reflects S-polarized light, the third polarization beam splitting element 237 transmits S-polarized light and reflects P-polarized light, and the second phase compensation element 238 converts S-polarized light into P-polarized light.

[0105] Due to the complex manufacturing process of the existing polarization conversion elements, the size of the polarization conversion unit, i.e., the width d', needs to be exactly matched and one-to-one corresponding to the size of the ommatidium unit in the compound eye lens, i.e., the aperture d0'. The two need to satisfy d0' = 2 * d' to achieve the best effect. The compound eye lens is the most important light homogenizing element in the entire PGU. The larger the size of the ommatidium unit, the worse the light homogenizing effect. Therefore, it is required that the size of the ommatidium unit d0' ≤ 2 mm. However, at this time, in order to ensure the uniformity of the whole machine, the thickness H0' of the compound eye lens needs to be ≥ 6.5 mm, where 3 ≤ H0' / d0' ≤ 6. At this time, the thickness H0' of the compound eye lens has exceeded the conventional manufacturing process of the compound eye lens, which is likely to result in a low processing yield of the compound eye lens and a risk of grinding and cracking.

[0106] When the polarization conversion element 230 of this embodiment is used with the compound eye lens, it does not need to correspond one-to-one to the ommatidium units in the compound eye lens, and there is no need to consider the reduction of light efficiency caused by the misalignment tolerance of the ommatidium units in the compound eye lens. The sizes of the compound eye lens and the ommatidium units can be freely designed without considering the size of the polarization conversion element 230, so that the aperture d0 of the ommatidium units in the compound eye lens and the thickness H0 of the ommatidium units can satisfy the conditional formula: 5 ≤ H0 / d0 ≤ 20, where d0 ≤ 1 mm and H0 ≤ 5 mm. By using the polarization conversion element 230 of this embodiment, the uniformity of the whole PGU can be increased to more than 90% while reducing the aperture d0 of the ommatidium units in the compound eye lens and the thickness H0 of the compound eye lens, effectively ensuring the uniformity of the whole machine.

[0107] It should be noted that this embodiment does not limit the material, shape, refractive index, etc. of the third prism 236 either. For example, the third prism 236 can be made of glass material or plastic material; the third prism 236 can be a parallelogram prism or a combination of a parallelogram prism and a triangular prism, etc.

[0108] It should be noted that this embodiment does not limit the types and structures of the second polarization beam splitter element 235 and the third polarization beam splitter element 237 either. For example, the second polarization beam splitter element 235 and the third polarization beam splitter element 237 can be metal wire grid polarization beam splitting films or coated polarization beam splitting films; when the second polarization beam splitter element 235 and the third polarization beam splitter element 237 adopt metal wire grid polarization beam splitting films, the direction of the wire grid lines can be set according to the reflection and transmission performance of different polarized lights; when the second polarization beam splitter element 235 and the third polarization beam splitter element 237 adopt coated polarization beam splitting films, the material, structure and thickness of the film layer can be set according to the reflection and transmission performance of different polarized lights.

[0109] It should be noted that the type, phase compensation amount, etc. of the second phase compensation element 238 are not limited in this embodiment. For example, the second phase compensation element 238 can be a phase retardation plate, and the phase retardation amount of the phase retardation plate can be determined according to the shape of the prism and the position where the phase retardation plate is arranged on the prism, etc.

[0110] It should be noted that the arrangement manners of the second prism 234, the second polarization beam splitting element 235, the third prism 236, the third polarization beam splitting element 237, and the second phase compensation element 238 are not limited in this embodiment. For example, the arrangement manner in which the second prism 234, the second polarization beam splitting element 235, the third prism 236, the third polarization beam splitting element 237, and the second phase compensation element 238 are arranged in sequence can be at least one of buckling, clamping, fitting, gluing, etc.

[0111] In some alternative embodiments of the present application, as Figure 8 shown, the first prism 231, the second prism 234, and the third lens 236 all have incident light surfaces 231a, 234a, 236a, and the first prism 231, the second prism 234, and the third lens 236 all have emergent light surfaces 231b, 234b, 236b. The incident light surfaces 231a, 234a, 236a are parallel to the emergent light surfaces 231b, 234b, 236b. The first prism 231, the second prism 234, and the third lens 236 also have first inclined surfaces 231c, 234c, 236c and second inclined surfaces 231d, 234d, 236d, and the first inclined surfaces 231c, 234c, 236c are parallel to the second inclined surfaces 231d, 234d, 236d.

[0112] A fourth polarization beam splitting element 239 is provided on the first inclined surface 231c of the first prism 231, and the fourth polarization beam splitting element 239 has the same transmissivity and reflectivity for polarized light as the first polarization beam splitting element 232. The first polarization beam splitting element 232 and the first phase compensation element 233 are arranged between the second inclined surface 231d of the first prism 231 and the first inclined surface 234c of the second prism 234. The second polarization beam splitting element 235 is arranged between the second inclined surface 234d of the second prism 234 and the first inclined surface 236c of the third prism 236, and the third polarization beam splitting element 237 and the second phase compensation element 238 are arranged on the second inclined surface 236d of the third prism 236.

[0113] In an alternative example, the first prism 231, the second prism 234, and the third lens 236 are parallelogram prisms, and the incident light surface and the emergent light surface, and the first inclined surface and the second inclined surface respectively correspond to the four sides of the parallelogram in the cross-section of the parallelogram prism.

[0114] Optionally, when the polarization conversion element 230 is an element that converts P-polarized light into S-polarized light, asFigure 8 As shown, among the natural light including P-polarized light and S-polarized light incident from the incident light surface 231a, the P-polarized light passes through the first polarization beam splitter 232, and the S-polarized light is reflected by the first polarization beam splitter 232. Among them, the P-polarized light passing through the first polarization beam splitter 232 is converted into S-polarized light by the first phase compensation element 233 and exits from the light exit surface 234b of the second prism 234. The S-polarized light reflected by the first polarization beam splitter 232 is reflected to the first inclined surface 231c of the first prism 231 and is reflected by the fourth polarization beam splitter 239 on the first inclined surface 231c and exits from the light exit surface 231b of the first prism 231.

[0115] Among the natural light including P-polarized light and S-polarized light incident from the incident light surface 234a, the S-polarized light passes through the second polarization beam splitter 235, and the P-polarized light is reflected by the second polarization beam splitter 235. Among them, the S-polarized light passing through the second polarization beam splitter 235 exits from the light exit surface 236b of the third prism 236. The P-polarized light reflected by the second polarization beam splitter 235 is reflected to the first inclined surface 234c of the second prism 234 and passes through the first phase compensation element 233 and is converted into S-polarized light by the first phase compensation element 233. The converted S-polarized light is reflected by the first polarization beam splitter 232 and passes through the first phase compensation element 233 again and is converted into P-polarized light by the first phase compensation element 233 and exits from the light exit surface 234b of the second prism 234.

[0116] Among the natural light including P-polarized light and S-polarized light incident from the incident light surface 236a, the P-polarized light passes through the third polarization beam splitter 237, and the S-polarized light is reflected by the third polarization beam splitter 237. Among them, the P-polarized light passing through the third polarization beam splitter 237 is converted into S-polarized light by the third phase compensation element 238 and exits. The S-polarized light reflected by the third polarization beam splitter 237 is reflected to the first inclined surface 236c of the third prism 236 and passes through the second polarization beam splitter 235, the second prism 234 and the first phase compensation element 233 and is converted into P-polarized light by the first phase compensation element 233. The converted P-polarized light passes through the first polarization beam splitter 232, the first prism 231 and the fourth polarization beam splitter 239 on the first inclined surface 231c of the first prism 231 and exits.

[0117] Optionally, when the polarization conversion element 230 is an element that converts S-polarized light into P-polarized light, the conversion process among the natural light including S-polarized light and P-polarized light incident from the incident light surfaces 231a, 234a, 236a can be correspondingly referred to the above description about Figure 8 and will not be repeated here.

[0118] In some alternative embodiments of the present application, the width d of the polarization conversion element 230 may satisfy the conditional expression: 0.2 mm ≤ d ≤ 2 mm. The luminous flux W1 of the effective polarized light before the polarization conversion element 230, the luminous flux W2 of the effective polarized light after the polarization conversion element 230, and the width d of the polarization conversion element 230 may satisfy the conditional expression: 0.35 ≤ W2 / W1*d ≤ 5. In an alternative example, the average transmittance Tp of the polarization beam splitter element for P-polarized light in the range of 45° ± 5° is ≥ 92%, the average transmittance Ts for S-polarized light is ≤ 0.15%, the extinction ratio EX of the two is ≥ 500:1, the phase compensation amount Δψ of the phase compensation element is λ / 2, the transmittance Tp of the P-polarized light of the phase compensation element is ≥ 95%, the luminous flux of the P-polarized light before the polarization conversion element 230 is W1, the luminous flux of the P-polarized light after the polarization conversion element 230 is W2, and the conversion efficiency W2 / W1 of the P-polarized light of the polarization conversion element 230 is ≥ 70%. By controlling the transmittance and reflectivity performance of each component in the polarization conversion element 230, the polarization conversion efficiency of the polarization conversion element 230 can be effectively improved.

[0119] In some alternative embodiments of the present application, such as Figure 3 shown, the angle θ between the first inclined surface and the light incident surface may satisfy the conditional expression: 30° ≤ θ ≤ 60°, and the phase compensation amount of the phase compensation element is λ / 2, where λ is the working wavelength band of the phase compensation element. For example, λ may be in the visible light wavelength band of 390 nm to 780 nm. Optionally, the angle θ between all the first inclined surfaces and the light incident surface in the polarization conversion element 230 may all satisfy: 40° ≤ θ ≤ 50°, and the phase compensation amounts of all the phase compensation elements in the polarization conversion element 230 may all be λ / 2. By making the angle between the first inclined surface of the prism in the polarization conversion element 230 and the light incident surface satisfy the above conditional expression, most of the incident light can undergo total internal reflection in the prism, thereby improving the utilization rate of light of the polarization conversion element 230. The thickness of the corresponding phase compensation element can be adjusted by adjusting the inclination angle of the prism, so as to achieve the best performance of polarization conversion, effectively improving the conversion efficiency of the polarization conversion element 230 and the light efficiency.

[0120] In some alternative embodiments of the present application, the thickness H of the polarization conversion assembly 2300 and the aperture D of the polarization conversion assembly 230 may satisfy the conditional expression: 5 ≤ D / H ≤ 125; where the ranges of H and D may be: 0.2 mm ≤ H ≤ 2 mm, 10 mm ≤ D ≤ 35 mm. As Figure 3As shown, the aperture D of the polarization conversion component 2300 may refer to the minimum of the dimensions in the x and y directions. Optionally, the aperture D of the polarization conversion component 230 may satisfy 15 mm ≤ D ≤ 25 mm. By making the thickness H of the polarization conversion component 2300 and the aperture D of the polarization conversion component 2300 satisfy the above conditional formula, the overall size of the polarization conversion component 2300 can be reduced, which is beneficial to reducing the size of the entire PGU, reducing the incident angle at the chip, improving the polarization purity, realizing the miniaturization of the PGU design, and improving the contrast of the entire PGU.

[0121] In some alternative embodiments of the present application, in the scheme where the polarization conversion elements 230 and the compound eye units 221 of the compound eye lens 220 correspond one by one, that is Figure 4 In the scheme, the widths D1 of the prisms in at least two polarization conversion elements 230 of the polarization conversion component 2300 may be different from the apertures of the compound eye units 221 in the compound eye lens 220. The aperture B1 of the compound eye unit 221 located at the center of the compound eye lens 220 and the aperture B2 of the compound eye unit 221 located around the center may satisfy: 1 ≤ B2 / B1 ≤ 2, where 0.5 mm ≤ B1 ≤ 3 mm. Correspondingly, the width of the first prism 231 located in the middle of the polarization conversion component 2300 may be made smaller than the width of the first prism 231 located at both ends of the polarization conversion component 2300. By making the compound eye lens 220 adopt a structure with different apertures of the compound eye units 221, the size of the compound eye units 221 can be adjusted according to the incident angle of the light in the actual optical path, thereby improving the uniformity and polarization conversion efficiency of the entire PGU.

[0122] In some alternative embodiments of the present application, in the scheme where the polarization conversion elements 230 and the compound eye units 221 of the compound eye lens 220 do not correspond one by one, that is Figure 7 In the scheme, at least two polarization conversion elements 230 of the polarization conversion component 2300 may be different, and the maximum width A1 of the prism and the minimum width A2 of the prism may satisfy: 1 ≤ A1 / A2 ≤ 10. Optionally, the width of the prism located in the middle of the polarization conversion component 2300 may be made larger than the width of the prism located at both ends of the polarization conversion component 2300; among them, the ranges of A1 and A2 may be: 1 mm ≤ A1 ≤ 2 mm, 0.2 mm ≤ A2 ≤ 1 mm. By making the widths of the prisms in at least two polarization conversion elements 231 of the polarization conversion component 2300 different, the size of the prism can be adjusted according to the incident angle of the light in the actual optical path, so as to more precisely control the light, improve the polarization conversion efficiency of the polarization conversion component 2300, and at the same time reduce the processing difficulty of the polarization conversion element 230 and improve the process yield of the polarization conversion element 230.

[0123] The polarization conversion element 230 of the embodiment of the present application can be directly applied to the PGU of the HUD for polarization light conversion, or can be applied to the PGU of the HUD after forming the polarization conversion assembly 2300 for polarization light conversion. Figure 9 The composition structure diagram of the image generation unit using the polarization conversion assembly 2300 of the embodiment of the present application is shown. As Figure 9 shown, the image generation unit may include: a light source system 210, a display chip 270, and a polarization conversion assembly 2300. Among them, the natural light emitted by the light source system 210 is subjected to polarization light conversion by the polarization conversion assembly 2300 and then projected onto the display chip 270 to generate an image. The natural light emitted by the light source system 210 includes S-polarized light and P-polarized light. The polarization conversion assembly 2300 may be an element that converts P-polarized light into S-polarized light, or may be an element that converts S-polarized light into P-polarized light. When the polarization conversion assembly 2300 is an element that converts P-polarized light into S-polarized light, the liquid crystal display principle of the display chip 270 can convert S-polarized light into P-polarized light. When the polarization conversion assembly 2300 is an element that converts S-polarized light into P-polarized light, the liquid crystal display principle of the display chip 270 can convert P-polarized light into S-polarized light.

[0124] In some alternative embodiments of the present application, as Figure 9 shown, the image generation unit may further include: a fly-eye lens 220, and the fly-eye lens 220 may be located between the light source system 210 and the polarization conversion assembly 2300. In the scheme where the polarization conversion elements 230 in the polarization conversion assembly 2300 do not correspond one-to-one to the fly-eye units in the fly-eye lens 220, the position of the polarization conversion assembly 2300 may also be interchanged with that of the fly-eye lens 220, that is, the polarization conversion assembly 2300 may be located between the light source system 210 and the fly-eye lens 220. The embodiment of the present application does not limit this. Similarly, when the polarization conversion element 230 of the embodiment of the present application is directly applied to the PGU, the installation position of the polarization conversion element 230 in the PGU may be the same as that of the polarization conversion assembly 2300, so it will not be described in detail here.

[0125] In some alternative embodiments of the present application, as Figure 9 shown, the display chip 270 may include an LCOS chip. In some other alternative embodiments of the present application, the display chip 270 may include an LCD chip.

[0126] In some alternative embodiments of the present application, as Figure 9As shown, the image generation unit may further include: a polarization beam splitter 250 and a polarization element 280. Among them, the polarization beam splitter 250 may be located in front of the display chip 270, and the polarization element 280 may be opposite to the polarization beam splitter 250 and the display chip 270. When the polarization conversion component 2300 is an element that converts P-polarized light into S-polarized light, the S-polarized light in the light projected onto the display chip 270 passes through the polarization beam splitter 250, is converted into P-polarized light by the display chip 270, and an image is generated. The P-polarized light emitted by the image is reflected by the polarization beam splitter 250 to the polarization element 280 and passes through the polarization element 280 and exits. When the polarization conversion component 2300 is an element that converts S-polarized light into P-polarized light, the P-polarized light in the light projected onto the display chip 270 passes through the polarization beam splitter 250, is converted into S-polarized light by the display chip 270, and an image is generated. The S-polarized light emitted by the image is reflected by the polarization beam splitter 250 to the polarization element 280 and passes through the polarization element 280 and exits. In an alternative example, the polarization beam splitter 250 may be a polarization beam splitter prism. Similarly, the application of the polarization conversion element 230 in the PGU in the embodiments of the present application may be the same as that of the polarization conversion component 2300, so it will not be described herein again.

[0127] In an alternative example, the average transmittance Tp of P-polarized light, the average transmittance Ts of S-polarized light, the average reflectance Rs of S-polarized light, and the average reflectance Rp of P-polarized light of the polarization beam splitter 250 in the range of 45° ± 20° may satisfy the conditional formula: Tp ≥ 85%, Ts ≤ 0.05%, Rs ≥ 80%, Rp ≤ 3%. The average transmittance Ts of S-polarized light and the average reflectance Rs of S-polarized light of the polarization element 280 in the range of 0° ± 20° may satisfy the conditional formula: Ts ≥ 85%, Rs ≤ 0.1%. In the HUD, when the windshield glass has a large angle, the reflectance of S-polarized light is more than 20 times that of P-polarized light. The image generation unit using S-polarized light to exit can improve the brightness at the human eye. For different incident light angles, by making the transmittance and reflectance of the polarization beam splitter 250 and the polarization element 280 in the image generation unit satisfy the above conditional formula, the reduction of light efficiency can be avoided, and by controlling the transmittance of S-polarized light, the interference of stray light in the dark state entering the image plane can be avoided, and the contrast of the whole image generation unit can be improved.

[0128] In some alternative embodiments of the present application, such as Figure 9As shown, the image generation unit may further include: a relay system 240, a phase compensation film 260, and an imaging lens 190. Among them, the light source system 210 may be a light source collimation and beam combining system, and an LED light source or a laser LD light source may be used. Taking the LED light source as an example, the natural light emitted by the LED is collimated by the collimation and beam combining system, and then the light is homogenized and shaped by the fly-eye lens 220. After that, the natural light is converted into a majority of P-polarized light and a minority of S-polarized light by the polarization conversion component 2300. The light emitted from the polarization conversion component 2300 is beam-shaped by the relay system 240. The function of the polarization beam splitter 250 is to transmit the P-polarized light and reflect the S-polarized light. Among them, the P-polarized light passes through the polarization beam splitter 250 and is incident on the LCOS chip 270 after passing through the phase compensation film 260. The LCOS chip 270 converts the P-polarized light into S-polarized light according to the liquid crystal display principle. Since there is a phase loss in the liquid crystal, the phase compensation is performed by the phase compensation film 260. The phase-compensated S-polarized light is reflected by the polarization beam splitter 250 to the polarization element 280, and then is projected onto the image plane through the imaging lens 290 because the polarization element 280 transmits it. Similarly, the application of the polarization conversion element 230 in the PGU in the embodiments of the present application may be the same as that of the polarization conversion component 2300, so it will not be described in detail here.

[0129] The polarization conversion element 230 and the image generation unit provided by the embodiments of the present application will be described below with reference to the accompanying drawings in conjunction with specific embodiments.

[0130] In some alternative embodiments of the present application, such as Figure 10As shown in the figure, the image generation unit mainly includes: a light source collimating and combining system 210, a fly-eye lens 220, a polarization conversion component 2300, a relay system 240, a polarization beam splitter 250, a phase compensation film 260, an LCOS chip 270, a polarization element 280, and an imaging lens 290. Among them, the light source in the light source collimating and combining system 110 uses an LED light source. The natural light emitted by the LED includes P-polarized light and S-polarized light. After being collimated by the collimating and combining system, the natural light is then converted into mostly S-polarized light and a small part of P-polarized light through the polarization conversion component 2300, which can effectively improve the utilization rate of light energy. Then, the fly-eye lens 220 is used to homogenize and shape the light. The light emitted from the fly-eye lens 220 is beam-shaped through the relay system 240. The function of the polarization beam splitter 250 is to transmit S-polarized light and reflect P-polarized light. Among them, the S-polarized light passes through the polarization beam splitter 250 and is incident on the LCOS chip 270 after passing through the phase compensation film 260. The LCOS chip 270 converts the S-polarized light into P-polarized light according to the liquid crystal display principle. Due to the phase loss of the liquid crystal, the phase compensation is carried out through the phase compensation film 260. The phase-compensated P-polarized light is reflected by the polarization beam splitter 250 to the polarization element 280. Since the polarization element 280 only allows one kind of linearly polarized light to pass through, only the P-polarized light passes through the polarization element 280, and then is projected onto the image plane through the imaging lens 290.

[0131] As Figure 11 shown in the figure, the polarization conversion component 2300 may include: a plurality of polarization conversion elements 230, and the plurality of polarization conversion elements 230 are glued together in sequence. Each polarization conversion element 230 may include a first prism 231, a metal wire grid sheet 232, a phase retardation film 233, and a second prism 234 that are glued together in sequence. Among them, the incident light surface 231a is parallel to the outgoing light surfaces 231b and 234b, and the metal wire grid sheet 232 and the phase retardation film 233 are glued to the second inclined surface 231d of the first prism 231 and the first inclined surface 234c of the second prism 234 in sequence. The polarization conversion component 2300 can convert most of the P-polarized light into S-polarized light, thereby improving the light efficiency of the entire image generation unit.

[0132] Among them, the included angle θ between the first inclined plane 231c and the incident light surface 231a is 45°, and the retardation amount of the phase retardation plate 233 is λ / 2, which can convert most P-polarized light into S-polarized light. The first prism 231 and the second prism 234 can be made of glass, and there is no specific refractive index requirement. The size of the polarization conversion component 2300 can meet the following conditions: the width d of the polarization conversion element 230 can range from 0.2 mm to 2 mm, 2 ≤ (the width D1 of the first prism + the width D2 of the metal wire grid sheet) / the width D3 of the phase retardation plate ≤ 10, and the aperture D of the polarization conversion component 2300 can range from 15 mm ≤ D ≤ 25 mm. The performance requirements of the metal wire grid sheet 232 can be: in the range of 45° ± 5°, the average transmittance Tp of P-polarized light ≥ 92%, the average transmittance Ts of S-polarized light ≤ 0.15%, and the extinction ratio > 500:1. The transmittance T of the phase retardation plate 233 ≥ 95%. The light flux of S-polarized light before the polarization conversion component 2300 is W1, the light flux of S-polarized light after the polarization conversion component 230 is W2, and the conversion efficiency of S-polarized light of the entire polarization conversion component 2300, W2 / W1 ≥ 70%.

[0133] The working wavelength band of the LED light source can be: 400 nm - 700 nm. The performance requirements of the polarization beam splitter 250 can be: in the range of 45° ± 20°, the average transmittance Ts of S-polarized light ≥ 85%, the average transmittance Tp of P-polarized light ≤ 0.05%, the average reflectance Rp of P-polarized light ≥ 80%, and the average reflectance Rs of S-polarized light ≤ 3%. The performance requirements of the polarization element 280 can be: in the range of 0° ± 20°, the average transmittance Tp of P-polarized light ≥ 85%, and the average reflectance Rp of P-polarized light ≤ 0.1%. The radial dimension r of the LCOS chip 270 can range from: 6 mm ≤ r ≤ 25 mm, and the preferred range can be: 8 mm ≤ d ≤ 20 mm. The working wavelength band of the phase retardation plate 2313 can be 380 - 780 mm, and the preferred range can be 400 nm - 650 nm.

[0134] Such as Figure 11As shown, when the polarization conversion component 2300 is used in conjunction with the compound eye lens 220, the natural light emitted from each compound eye unit 221 in the compound eye lens 220 enters the first prism 231 from the incident light surface 231a of the corresponding polarization conversion element 230 in the polarization conversion component 2300. The P-polarized light in the natural light passes through the metal wire grid 232, and the S-polarized light in the natural light is reflected by the metal wire grid 232. Among them, the P-polarized light passing through the metal wire grid 232 passes through the phase retarder 233 and is converted into S-polarized light by the phase retarder 233, and exits from the exit light surface 234b of the second prism 234. The S-polarized light reflected by the metal wire grid 232 is reflected to the first inclined surface 231c of the first prism 231 and exits from the exit light surface 231b of the first prism 231 after being reflected by the reflective film on the first inclined surface 231c. The polarization conversion component 2300 can convert most of the P-polarized light in the natural light emitted from the compound eye lens 220 into S-polarized light.

[0135] Relative to Figure 1 pieces Figure 2 In the existing technical solutions, due to the large tolerances generated by the processing technology, the conversion efficiency is only 40%-50%. In this embodiment, the polarization conversion element 230 has a simple process, a small offset tolerance, and the conversion efficiency can reach 70%-80%, which can improve the light emission efficiency of the entire PGU.

[0136] In some other alternative embodiments of the present application, as Figure 12A and Figure 12B shown, the polarization conversion component 2300 may include: a plurality of polarization conversion elements 230, and the plurality of polarization conversion elements 230 are sequentially glued. Each polarization conversion element 230 may include a first prism 231, a metal wire grid 232, a phase retarder 233, and a second prism 234. Among them, the incident light surface 231a is parallel to the exit light surfaces 231b and 234b, and the metal wire grid 232 and the phase retarder 233 are sequentially glued on the second inclined surface 231d and the first inclined surface 231c of the first prism 231. The polarization conversion component 2300 can convert most of the S-polarized light into P-polarized light, thereby improving the light efficiency of the entire image generation unit.

[0137] Among them, the included angle θ between the first inclined surface 231c and the incident light surface 231a in the polarization conversion element 230 is 45°, and the retardation amount of the phase retarder 233 is λ / 2, so that the conversion of polarized light can be realized, and most of the S-polarized light can be converted into P-polarized light. The first prism 231 and the second prism 234 can be made of plastic material and have no specific refractive index requirements.

[0138] Such as Figure 12A and Figure 12BAs shown, when the polarization conversion component 2300 is used in cooperation with the compound eye lens 220, the natural light emitted from each compound eye unit 221 in the compound eye lens 220 enters the first prism 231 from the incident light surface 231a of the corresponding polarization conversion element 230 in the polarization conversion component 2300. The S-polarized light in the natural light passes through the metal wire grid 232, and the P-polarized light in the natural light is reflected by the metal wire grid 232. Among them, the S-polarized light passing through the metal wire grid 232 passes through the phase retarder 233 and is converted into S-polarized light by the phase retarder 233, and exits from the exit light surface 234b of the second prism 234. The P-polarized light reflected by the metal wire grid 232 is reflected to the first inclined surface 231c of the first prism 231 and exits from the exit light surface 231b of the first prism 231 after being reflected by the reflective film on the first inclined surface 231c. The polarization conversion component 2300 can convert most of the S-polarized light in the natural light emitted from the compound eye lens 220 into P-polarized light.

[0139] The metal wire grid 232 can be designed to transmit P-polarized light and reflect S-polarized light, or to transmit S-polarized light and reflect P-polarized light. It only needs to rotate the metal wire grid 232 by 90°, without special customization. As Figure 13A and Figure 13B shown, when the metal wire grid 232 transmits P-polarized light and reflects S-polarized light, the wire grid lines of the metal wire grid 232 are horizontal stripes perpendicular to the light beam incident surface. As Figure 14A and Figure 14B shown, when the metal wire grid 232 transmits S-polarized light and reflects P-polarized light, the wire grid lines of the metal wire grid 232 are vertical stripes perpendicular to the light beam incident surface. Since the metal wire grid 232 only needs to be rotated by 90° when it transmits P-polarized light and reflects S-polarized light and when it transmits S-polarized light and reflects P-polarized light, and the phase retarder 233 remains stationary, without special customization, the manufacturing process of the polarization conversion element 230 can be further simplified.

[0140] In some other alternative embodiments of the present application, as Figure 15AAs shown, the widths of the first prisms of several polarization conversion elements 230 in the polarization conversion component 2300 and the apertures of the compound eye units 221 in the compound eye lens 220 can be different, that is, the apertures of the compound eye units 221 in the compound eye lens 220 are inconsistent, and the widths of the first prisms of the polarization conversion elements 230 in the polarization conversion component 2300 are inconsistent. The aperture of the compound eye unit 221 located at the center of the compound eye lens 220 can be made smaller than the aperture of the compound eye units 221 located around the center. Correspondingly, the width of the first prism 231 located in the middle of the polarization conversion component 2300 can be made smaller than the widths of the first prisms 231 located at both ends of the polarization conversion component 2300. Among them, the aperture B1 of the compound eye unit 221 located at the center of the compound eye lens 220 and the aperture B2 of the compound eye units 221 located around the center can satisfy: 1 ≤ B2 / B1 ≤ 2, where 0.5 mm ≤ B1 ≤ 3 mm. By making the compound eye lens 220 have a structure with a smaller width in the middle and a larger width around the compound eye units 221, the uniformity and polarization conversion efficiency of the entire PGU can be improved.

[0141] As Figure 15B shown, the widths of the prisms of several polarization conversion elements 230 in the polarization conversion component 2300 can be inconsistent, that is, the sizes of d1, d2, d3, d4, and dn are not equal. Among them, the width d3 of the prism located in the middle is the largest, and the widths d1 and dn of the prisms located at both ends are the smallest. In some other embodiments of the present application, it is also possible to select to make the widths of the prisms of several polarization conversion elements 230 in the polarization conversion component 2300 gradually change to match the angle of the incident light at the front end. Due to the inconsistent widths of the prisms of several polarization conversion elements 230 in the polarization conversion component 2300 and the relatively high collimation of the middle light in the incident light, the width of the middle prism can be increased. The width d3 of the middle prism can be controlled between 1 mm and 2 mm, thereby improving the process yield. The widths d1 and dn of the prisms at both ends can be controlled between 0.2 mm and 1 mm.

[0142] In still some alternative embodiments of the present application, as Figure 16 shown, the image generation unit mainly can include: a light source system 310, a compound eye lens 220, a polarization conversion component 2300, a reflector 340, a cylindrical lens 350, and an LCD chip 360. Among them, the natural light including P-polarized light and S-polarized light emitted by the light source system 310, after being homogenized by the compound eye lens 220, enters the polarization conversion component 2300, and the polarization conversion component 2300 converts the S-polarized light into P-polarized light. The emitted P-polarized light has its optical path folded by the reflector 340 and is projected onto the LCD chip through the cylindrical lens. The P-polarized light is converted into S-polarized light and emitted according to the liquid crystal display principle of the LCD chip. By performing the polarization light conversion after the light source system 310, the light efficiency of the entire image generation unit can be greatly improved.

[0143] In some further alternative embodiments of the present application, as Figure 17A shown, the polarization conversion element 230 may include a fourth metal wire grid sheet 239, a first prism 231, a first metal wire grid sheet 232, a first phase retardation sheet 233, a second prism 234, a second metal wire grid sheet 235, a third prism 236, a third metal wire grid sheet 237, and a second phase retardation sheet 238 that are sequentially glued together. Among them, the incident light surfaces 231a, 234a, 236a are parallel to the outgoing light surfaces 231b, 234b, 236b. The first metal wire grid sheet 232 and the first phase retardation sheet 233 are sequentially glued onto the second inclined surface 231d of the first prism 231 and the first inclined surface 231c of the second prism 231. The second metal wire grid sheet 235 is glued onto the second inclined surface 234d of the second prism 234 and the first inclined surface 236c of the third prism 236. The third metal wire grid sheet 237 and the second phase retardation sheet 238 are sequentially glued onto the second inclined surface 231d of the third prism 231. The fourth metal wire grid sheet 239 is glued onto the first inclined surface 231c of the first prism 231.

[0144] Among them, the angle θ between the first inclined surface and the incident light surface is 45°, and the retardation amount of the phase retardation sheet is λ / 2, which can convert most P-polarized light into S-polarized light. The prism can be made of glass and has no specific refractive index requirement.

[0145] The polarization conversion assembly 2300 composed of the Figure 17A polarization conversion element 230 in may include: a plurality of polarization conversion elements 230, and the plurality of polarization conversion elements 230 are sequentially glued together. The size of each polarization conversion assembly 2300 may satisfy that the width d of the polarization conversion element 230 may range from 0.2 mm to 2 mm, and the aperture D of the polarization conversion assembly 2300 may range from 15 mm ≤ D ≤ 25 mm.

[0146] When the polarization conversion tuple 2300 of the present embodiment is applied to an image generation unit, as Figure 17BAs shown in the figure, the position of the polarization conversion tuple 2300 can be set arbitrarily. It can be set before the compound eye lens 220 or after the compound eye lens 220. The polarization conversion elements 230 in the polarization conversion tuple 2300 do not need to correspond one by one to the compound eye units in the compound eye lens 220. There is no need to consider the reduction in optical efficiency caused by the misalignment tolerance between the polarization conversion elements 230 and the compound eye units in the compound eye lens 220. The sizes of the compound eye lens 220 and the compound eye units can be freely designed without considering the size of the polarization conversion elements 230. The aperture d0 of the compound eye units in the compound eye lens and the thickness H0 of the compound eye units can satisfy the conditional formula: d0 ≤ 1 mm, H0 ≤ 5 mm, 5 ≤ H0 / d0 ≤ 20. By using the polarization conversion assembly 2300 of this embodiment, the uniformity of the entire PGU can be increased to more than 90% while reducing the width d0 of the compound eye units in the compound eye lens 220 and the thickness H0 of the compound eye lens, effectively ensuring the uniformity of the entire PGU.

[0147] As Figure 17A shown in the figure, the natural light emitted by the light source system 310 enters the first prism 231 from the incident light surface 231a of the polarization conversion element 230 in the polarization conversion assembly 2300. The P-polarized light in the natural light passes through the first metal wire grid 232, and the S-polarized light in the natural light is reflected by the first metal wire grid 232. Among them, the P-polarized light passing through the first metal wire grid 232 passes through the first phase retardation plate 233 and is converted into S-polarized light by the first phase retardation plate 233, and exits from the exit surface 234b of the second prism 234. The S-polarized light reflected by the first metal wire grid 232 is reflected to the first inclined surface 231c of the first prism 231 and is reflected by the fourth metal wire grid 239 on the first inclined surface 231c and exits from the exit surface 231b of the first prism 231.

[0148] The natural light emitted by the light source system 310 enters the second prism 234 from the incident light surface 234a of the polarization conversion element 230 in the polarization conversion assembly 2300. The S-polarized light in the natural light passes through the second metal wire grid 235, and the P-polarized light in the natural light is reflected by the second metal wire grid 235. Among them, the S-polarized light passing through the second metal wire grid 235 exits from the exit surface 236b of the third prism 236. The P-polarized light reflected by the second metal wire grid 235 is reflected to the first inclined surface 234c of the second prism 234, passes through the first phase retardation plate 233 and is converted into S-polarized light by the first phase retardation plate 233. The converted S-polarized light is reflected by the first metal wire grid 232 and passes through the first phase retardation plate 233 again and is converted into P-polarized light by the first phase retardation plate 233 and exits from the exit surface 234b of the second prism 234.

[0149] The natural light emitted by the light source system 310 enters the third prism 236 from the light incident surface 236a of the polarization conversion element 230 in the polarization conversion assembly 2300. The P-polarized light in the natural light passes through the third metal wire grid 237, and the S-polarized light is reflected by the third metal wire grid 237. Among them, the P-polarized light passing through the third metal wire grid 237 is converted into S-polarized light by the third phase retarder 238 and then exits. The S-polarized light reflected by the third metal wire grid 237 is reflected to the first inclined surface 236c of the third prism 236, and passes through the second metal wire grid 235, the second prism 234 and the first phase retarder 233, and is converted into P-polarized light by the first phase retarder 233. The converted P-polarized light passes through the first metal wire grid 232 and the first prism 231, and exits through the fourth metal wire grid 239 on the first inclined surface 231c of the first prism 231.

[0150] The polarization conversion assembly 2300 can convert most of the P-polarized light in the natural light emitted from the light source system 310 into S-polarized light.

[0151] Relative to Figure 1 pieces Figure 2 In the existing technical solutions, since there is no need to match with the compound eye unit in this embodiment, there is no need to consider the reduction of light efficiency caused by misalignment tolerance, and the conversion efficiency can reach 55%-65%, which can improve the light output efficiency of the entire PGU.

[0152] It should be noted that the descriptions of the light source system 310, the mirror 340, the cylindrical lens 350 and the LCD chip 360 in the image generation unit of Figure 17B can be referred to the relevant descriptions in Figure 16 . It should be noted that Figure 17A The polarization conversion element 230 of Figure 17B can be used not only in the image generation unit shown in Figure 10 , but also in other types of image generation units, for example, it can be used in the image generation unit shown in

[0153] The above specific embodiments do not constitute a limitation to the protection scope of the present disclosure. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present disclosure shall be included within the protection scope of the present disclosure.

Claims

1. A polarization conversion element, characterized in that, It includes a first prism, a first polarization beam splitter element, a first phase compensation element, and a second prism that are arranged in sequence.

2. The polarization conversion element according to claim 1, wherein The first polarization beam splitter element allows P-polarized light to pass through and reflects S-polarized light. The first phase compensation element converts P-polarized light into S-polarized light.

3. The polarization conversion element according to claim 1, wherein The first polarization beam splitter element allows S-polarized light to pass through and reflects P-polarized light. The first phase compensation element converts S-polarized light into P-polarized light.

4. The polarization conversion element according to any one of claims 1 to 3, characterized in that, When used with a compound eye lens, the width d of the polarization conversion element and the aperture d0 of the compound eye unit in the compound eye lens satisfy: 0.8 ≤ d0 / d ≤ 1.

2.

5. The polarization conversion element according to any one of claims 1 to 3, characterized in that, The width D1 of the first prism, the width D2 of the first polarization beam splitter element, and the width D3 of the first phase compensation element satisfy: 2 ≤ (D1 + D2) / D3 ≤ 10.

6. The polarization conversion element according to any one of claims 1 to 3, characterized in that, The width D1 of the first prism and the width D4 of the second prism satisfy: 0.8 ≤ D1 / D4 ≤ 1.

2.

7. A polarization conversion component, characterized in that, It includes: At least two polarization conversion elements, and the at least two polarization conversion elements are arranged in sequence; wherein, Each of the polarization conversion elements includes: a first prism, a first polarization beam splitter element, a first phase compensation element, and a second prism that are arranged in sequence.

8. An image generation unit, characterized in that, It includes: A light source system, a display chip, and the polarization conversion element according to any one of claims 1 to 6 or the polarization conversion assembly according to claim 7; wherein, The natural light emitted by the light source system is subjected to polarization conversion by the polarization conversion element or the polarization conversion assembly and then projected onto the display chip to generate an image.

9. A head-up display system, characterized in that, It includes the image generation unit according to claim 8.

10. A vehicle, characterized in that, It includes the head-up display system according to claim 9.

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