Display devices, vehicles, and imaging methods that output single-polarized image light.

Abstract

This application discloses a display device, a vehicle, and an imaging method for outputting single-polarized image light, relating to the field of optics. The optical waveguide unit in the display device further includes: an output element with a single polarization response and a polarization conversion element; the polarization conversion element is located within a first principal plane, a second principal plane, or a waveguide substrate, and is used to convert a second polarization component light in the guided light that is different from the first polarization component light into the first polarization component light; the output element is used to expand and couple the first polarization component light of the guided light to form a first output light. In this display device, through the output element and polarization conversion element with a single polarization response, the polarization conversion element converts the second polarization component light that cannot be coupled out by the output element into the first polarization component light that can be coupled out, realizing the coupled output of all image light rays, improving light energy utilization efficiency, and thus improving the image brightness of the display system.

Description

Technical Field

[0001] This application relates to the field of optics, and in particular to an imaging method for a display device, a vehicle, and an output of single-polarized image light. Background Technology

[0002] With the continuous development of society, automobiles have become an indispensable means of transportation in people's daily lives. However, with the increasing number of cars, the frequency of traffic accidents is also rising. To improve driving safety, in-vehicle head-up display (HUD) systems can assist driving. HUDs can help drivers avoid interruptions in attention or loss of awareness, thus increasing driving safety.

[0003] Currently, head-up display (HUD) systems mainly fall into three categories: direct projection (Entry HUD), indirect integration (Combiner HUD), and windshield integration (Windows-Shield HUD, also known as W-HUD). W-HUD uses the windshield as a component of the optical system, creating a suspended virtual image at least 2 meters in front of the driver. This projects important information needed by the driver onto the windshield, blending the virtual image with the surrounding real-world scenery. The light from this blended image is reflected and enters the driver's eyes, allowing them to see the merged virtual image without needing to look down at the instrument panel, thus reducing the impact of looking down on safe driving. However, because windshields require high transparency and low reflectivity, strong image light is needed to meet the brightness requirements of various driving scenarios. This increases the power consumption of the HUD and places higher demands on the brightness achievable by current HUD technology.

[0004] Therefore, improving the image brightness and reducing the power consumption of display systems are technical problems that urgently need to be solved by those in the field. Summary of the Invention

[0005] The purpose of this application is to provide an imaging method for a display device, a vehicle, and an output single-polarized image light, which can improve the image brightness of the display system and reduce the power consumption of the display system.

[0006] To address the aforementioned technical problems, this application provides a display device, comprising: an image generation unit and an optical waveguide unit. The optical waveguide unit includes a waveguide substrate and an input element. The waveguide substrate includes a first principal plane and a second principal plane. The image generation unit generates a first input light carrying image information. The input element couples the first input light into the waveguide substrate, forming guided light that propagates back and forth between the first principal plane and the second principal plane in a total internal reflection manner within the waveguide substrate. The optical waveguide unit further includes: an output element having a single polarization response and a polarization conversion element.

[0007] The polarization conversion element is located in the first main plane, the second main plane, or the waveguide substrate, and is used to convert the second polarization component light, which is different from the first polarization component light, into the first polarization component light in the transmitted light.

[0008] The output element is used to expand and couple the first polarization component of the guided light to form a first output light.

[0009] Preferably, the polarization conversion element covers the waveguide substrate area where the output element is located, but does not cover the waveguide substrate area where the input element is located.

[0010] Preferably, the display device further includes: a transparent substrate; the transparent substrate is used to receive and reflect the first output light to form a second output light for user observation.

[0011] Preferably, the transparent substrate is the windshield of a vehicle.

[0012] Preferably, the first polarization component light is linearly polarized light with a preset polarization direction, and the second polarization component light is linearly polarized light with a polarization direction perpendicular to the polarization direction of the first polarization component light.

[0013] Preferably, the first output light is incident on the transparent substrate, and the electric vector direction of the first output light is perpendicular to the first incident surface, wherein the first incident surface is jointly determined by a straight line in the propagation direction of the first output light and a straight line in the normal direction of the transparent substrate.

[0014] Preferably, the polarization conversion element includes at least one birefringent coating or birefringent film layer.

[0015] Preferably, the polarization conversion element is an element with birefringence effect.

[0016] To address the aforementioned technical problems, this application also provides a vehicle that includes the aforementioned display device.

[0017] To address the aforementioned technical problems, this application also provides an imaging method for outputting a single-polarization image light, applied to a display device comprising an image generation unit and an optical waveguide unit. The optical waveguide unit includes a waveguide substrate and an input element. The waveguide substrate includes a first principal plane and a second principal plane. The optical waveguide unit further includes an output element having a single polarization response and a polarization conversion element. The method includes:

[0018] Acquire guided light; wherein, the guided light is light that is coupled to the waveguide substrate by the first input light carrying image information generated by the image generation unit through the input element, and propagates between the first principal plane and the second principal plane of the waveguide substrate in a total internal reflection manner;

[0019] The second polarization component light, which is different from the first polarization component light, is converted into the first polarization component light by a polarization conversion element located in the first main plane, the second main plane, or the waveguide substrate.

[0020] The first polarization component of the guided light is expanded and coupled out by the output element having a single polarization response to form a first output light.

[0021] This application provides a display device comprising: an image generation unit and an optical waveguide unit. The optical waveguide unit includes a waveguide substrate and an input element. The waveguide substrate includes a first principal plane and a second principal plane. The image generation unit generates a first input light carrying image information. The input element couples the first input light into the waveguide substrate, forming guided light that propagates back and forth between the first and second principal planes via total internal reflection within the waveguide substrate. The optical waveguide unit further includes: an output element with a single polarization response and a polarization conversion element. The polarization conversion element is located within the first principal plane, the second principal plane, or the waveguide substrate, and is used to convert a second polarization component of the guided light, which is different from the first polarization component, into a first polarization component. The output element expands and couples the first polarization component of the guided light to form a first output light. In this display device, through the output element and the polarization conversion element with a single polarization response, the polarization conversion element converts the second polarization component that cannot be coupled out by the output element into the first polarization component that can be coupled out, achieving the coupling and output of all image light rays, improving light energy utilization efficiency, and thus improving the image brightness of the display system.

[0022] In addition, this application also provides a vehicle and an imaging method for outputting a single polarized image light, which has the same or corresponding technical features as the aforementioned display device and achieves the same effect. Attached Figure Description

[0023] To more clearly illustrate the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A schematic diagram illustrating the relationship between a driver's line of sight and the windshield panel, provided as an embodiment of this application;

[0025] Figure 2 Reflectivity curves of different polarized rays at the air-glass interface provided in the embodiments of this application;

[0026] Figure 3 A schematic diagram of a conventional diffractive optical waveguide provided in an embodiment of this application;

[0027] Figure 4 A cross-sectional view of light transmission in a diffractive waveguide provided in an embodiment of this application;

[0028] Figure 5 A HUD system using a diffractive waveguide is provided in this application embodiment;

[0029] Figure 6 The overall reflectance curves of unpolarized image light from a conventional HUD system provided in the embodiments of this application and the single S-polarized line-polarized light formed by polarization conversion proposed in this application after reflection from two surfaces of the windshield;

[0030] Figure 7(a) is a cross-sectional view of the diffraction waveguide light transmission of a display device using an output element with no polarization response according to an embodiment of this application;

[0031] Figure 7(b) is a cross-sectional view of the light transmission of a diffractive waveguide in a display device using an output element with a single polarization response characteristic, according to an embodiment of this application.

[0032] Figure 8 A cross-sectional view of the diffraction waveguide light transmission of a display device employing an output element with a single polarization response and a polarization conversion element corresponding to the position of the output element, provided for an embodiment of this application;

[0033] Figure 9(a) is a schematic diagram of a polarization conversion element located on the first principal plane of the waveguide plate where the output element is located, according to an embodiment of this application;

[0034] Figure 9(b) is a schematic diagram of a polarization conversion element located in a waveguide plate according to an embodiment of this application. Detailed Implementation

[0035] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this application.

[0036] The core of this application is to provide an imaging method for a display device, a vehicle, and an output single-polarized image light, which is used to improve the image brightness of the display system and reduce the power consumption of the display system.

[0037] To improve driving safety, head-up display (HUD) systems can assist drivers. HUDs prevent drivers from losing focus or awareness of their surroundings, thus increasing driving safety. However, due to the high transparency and low reflectivity requirements of automotive windshields, strong image light is needed to meet the brightness demands of various driving scenarios. This application utilizes the characteristic that conventional automotive windshields have a significantly higher reflectivity for incident S-polarized light than P-polarized light to propose an optical waveguide display device that outputs single-polarized image information. Selectively, this single-polarized image light can be S-polarized light incident on the windshield, thereby improving the image brightness of the display system.

[0038] Specifically, the optical waveguide unit is improved to output all transmitted image rays as image rays with a single polarization characteristic. A polarization conversion element or depolarization element is added to an interface or within the optical waveguide, and the output element is designed as a diffraction grating that responds only to a single polarization. The display device provided in this application is applicable to virtual reality (VR) or augmented reality (AR) displays, as well as head-up displays (HUDs).

[0039] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. The display device provided by the present application includes: an image generation unit and an optical waveguide unit. The optical waveguide unit includes a waveguide substrate and an input element. The waveguide substrate includes a first main plane and a second main plane. The image generation unit is used to generate a first input light carrying image information. The input element is used to couple the first input light into the waveguide substrate, forming guided light that propagates back and forth between the first and second main planes in a total internal reflection manner within the waveguide substrate. The optical waveguide unit further includes: an output element having a single polarization response and a polarization conversion element.

[0040] The polarization conversion element is located in the first principal plane, the second principal plane, or the waveguide substrate, and is used to convert the second polarization component light, which is different from the first polarization component light, into the first polarization component light in the transmitted light.

[0041] The output element is used to expand and couple the first polarization component of the guided light to form the first output light.

[0042] In current display devices, diffractive waveguides couple image light emitted from an image generation unit into the waveguide interior via grating diffraction, forming guided light that propagates via total internal reflection. The image light is further expanded and coupled out through a grating element, thereby achieving a larger observable image range. Typically, a diffractive waveguide includes an input element that diffracts the input light emitted from the image generation unit to form a first guided light propagating within the waveguide via total internal reflection. The waveguide also includes a pupil expander element that diffracts the first guided light to form a second guided light whose beam size is expanded in at least one direction. Finally, the waveguide includes an output element that diffracts the second guided light to form an expanded output image light. It should be noted that in this application, the output element is an output element with a single polarization response. An output element with a single polarization response means that the element has a higher diffraction efficiency for light with a single polarization characteristic than for light with a different single polarization characteristic. In particular, it means that the element has a much higher (e.g., more than 10 times higher) diffraction efficiency for light with a single polarization characteristic than for light with a polarization direction perpendicular to that single polarization characteristic.

[0043] Because the image light undergoes multiple grating diffractions and propagation direction deflections, even if the image light provided by the image generation unit is single-polarized light, the transmitted light formed by its coupling into the waveguide will still be polarized disordered. After this polarized disordered transmitted light is coupled out by the output element of the optical waveguide, the polarization state of the output image light will also be polarized disordered. This polarized disordered image light includes both P-polarization and S-polarization components. Due to the polarization selectivity of the windshield reflection, the P-polarization component in the image light will be largely wasted. Therefore, in practice, a special output element grating design can be used to ensure that the grating in this area has diffraction efficiency or high diffraction efficiency only for S-polarized light, while having no diffraction or low diffraction efficiency for P-polarized light. This achieves a single polarization of the waveguide's output light. However, this approach simply advances the polarization selection of the windshield to the output element of the waveguide, resulting in a waste of the P-polarized component of the transmitted light. Therefore, based on the diffractive waveguide, a polarization conversion layer is constructed on the diffractive waveguide at the position corresponding to the output element. Combined with an output element that has polarization selection characteristics, all image light energy transmitted within the waveguide is converted into S-polarized light output, thereby significantly improving the image light energy utilization rate of the display system, increasing the brightness of the displayed image, and reducing the power consumption of the display system.

[0044] Figure 1This diagram illustrates the relationship between a driver's line of sight and the windshield, as provided in an embodiment of this application. The angle of a conventional automotive windshield relative to the vertical direction is mostly between 55° and 65°, i.e., as shown... Figure 1 The angle α shown is typically 60°. The driver's line of sight is nearly horizontal when driving. Figure 1 The geometric relationship can be used to approximate the angle between the incident ray and the vertical direction before it strikes the windshield in a HUD system based on windshield reflection. Figure 1 The median angle β, typically 30°. This is the angle of incidence onto the windshield, i.e. Figure 1 The midpoint angle θ is 60°. The refractive index of a typical automotive windshield is around 1.5. Therefore, we can calculate the reflectivity curves for different polarized rays at the air-glass interface when the refractive index is 1.5, based on the incident angle. Figure 2 The incident angle-dependent reflectivity curves of different polarized rays at the air-glass interface provided in the embodiments of this application. Figure 2 The solid line represents the reflectance curve of S-polarized light at the air-glass interface, and the dashed line represents the reflectance curve of P-polarized light at the air-glass interface. It can be seen that for a wide range of incident angles, the reflectance Rs of S-polarized light is significantly higher than that of P-polarized light Rp. Particularly near the typical incident angle θ = 60°, the reflectance of P-polarized light is approximately zero, leading to energy loss in this polarized component of the incident light, resulting in insufficient brightness or high power consumption in the HUD display. If the P-polarized light in the incident light can be converted into S-polarized light with higher reflectance, the overall light energy transmission efficiency of the display system can be improved, thereby increasing the brightness of the display system.

[0045] HUD systems based on diffractive waveguide technology have advantages in terms of size and display effect. Figure 3 This is a schematic diagram of a conventional diffractive optical waveguide provided in an embodiment of this application. It includes a waveguide substrate (SUB1), an input element (DOE1), and a first guided light (B1) that transmits within the waveguide substrate via total internal reflection by diffraction of image light generated by an image generation unit. P0，R B1 P0，G B1 P0，B The diffractive waveguide also includes a diffractive pupil expander (DOE2), which forms a second guided light (B2) by diffracting the first guided light. P0，R B2 P0，G B2 P0，B ), and in the first direction ( Figure 3 The beam is expanded in the direction of SX, and an output element (DOE3) is used to form the output light by diffracting the second guided light, and the output light is in a second direction different from the first direction. Figure 3 Beam extension is achieved in the SY direction. Figure 4This is a cross-sectional view of a diffractive waveguide light transmission provided in an embodiment of this application. The input element (DOE1) receives and diffracts the input light (IN) generated by the image light generation unit to form a guided light that propagates in the waveguide substrate (SUB1) in a total internal reflection manner. The output element (DOE3) diffracts the guided light to form an output beam (OUT).

[0046] Figure 5 This application provides a HUD system based on a diffractive waveguide. The HUD system includes an image generation unit for generating light rays (IN) carrying image information. The image generation unit includes an image source (IMG0) and an imaging lens group (Lens). The generated image light enters the diffractive waveguide through a diffraction entrance pupil element (DOE1), and after propagation through the diffraction waveguide, it is coupled out by a diffraction exit pupil element (DOE3) and then incident on the windshield. Further, the image light is reflected by the windshield and enters the observer's eye. The light generated by the image generation unit can be single-polarized light, unpolarized light, or partially polarized light, depending on the selection of the image source (IMG0). Typically, for a liquid crystal on silicon (LCOS) image source, the generated image light is single-polarized light, while for a digital array mirror (DMD) image source, the generated image light is unpolarized light. However, even if the input light generated by the image generation unit is single-polarized light, after the single-polarized image light is transmitted through the diffractive waveguide beam expander, the output image light will usually be converted into unpolarized light or partially polarized light. As mentioned above, the P-polarization component in these unpolarized or partially polarized lights will have a large energy loss. Figure 6 The overall reflectance curves of unpolarized image light from a conventional HUD system provided in the embodiments of this application and the single S-polarized line polarized light based on polarization conversion proposed in this application are reflected by the two surfaces of the windshield. Figure 6 The dashed line represents the angle-reflectivity curve of unpolarized light, while the solid line represents the angle-reflectivity curve of S-polarized light. It can be seen that the reflectivity of S-polarized light is higher than that of unpolarized light in almost the entire angular range, especially around the typical incident angle of 60 degrees, where the reflectivity of S-polarized light is almost twice that of unpolarized light.

[0047] To expand the input light beam and thus increase the field of view of the output element, the optical waveguide unit of the display device also includes a pupil expander. The pupil expander diffracts the guided light and changes its propagation direction. In practice, through special grating design or selection, the input element (DOE1), pupil expander (DOE2), and output element (DOE3) on the optical waveguide composed of a diffraction grating can have certain polarization response characteristics. However, because the light is reflected back and forth within the waveguide substrate (SUB1) by total internal reflection, and the light propagation direction changes during its transmission within the optical waveguide, the polarization of the beam-expanded guided light (e.g., the second guided light) within the optical waveguide becomes disordered. In this case, even if the output element (DOE3) has a single polarization response characteristic, it will only couple and output that specific single polarized light, wasting image light that is different from that specific single polarized light, and causing image light energy loss. Therefore, this embodiment employs an output element (DOE3) with a single polarization response characteristic, and constructs a polarization conversion element or depolarization element on the optical waveguide at a position corresponding to the output element (DOE3). This polarization conversion element or depolarization element can continuously convert image light that would otherwise be unable to be output by the output element (DOE3) into a polarization state that can be responded to by the output element (DOE3), and then continuously diffracted multiple times by the output element (DOE3), ultimately achieving a single polarization state output for all image light transmitted through the optical waveguide. This single polarization state can be controlled to be an S-polarization state with high reflectivity of the windshield, thereby improving the overall optical transmission efficiency of the display system.

[0048] Figure 7(a) is a cross-sectional view of the diffraction waveguide light transmission of a display device using an output element with no polarization response according to an embodiment of this application. Figure 7(b) is a cross-sectional view of the diffraction waveguide light transmission of a display device using an output element with a single polarization response characteristic according to an embodiment of this application. Due to the total internal reflection propagation mode of the guided light in the waveguide plate and the multiple beam expansion and turning of the beam, the guided light (B2) is usually disordered polarized light or composite polarized light containing various polarization states before it is transmitted to the output element (DOE3). When the output element has no polarization response characteristic, as shown in Figure 7(a), it indiscriminately couples the guided light of various polarization states to the outside of the waveguide plate to form the output image light. The output image light is also composite polarized light. After the composite polarized image light is incident on the windshield, due to the polarization selective reflection characteristic of the windshield, nearly half of the light energy is ineffective light, resulting in wasted light energy. When the output element has a single polarization response characteristic, as shown in Figure 7(b), it will couple out a certain polarization component of the guided light, which is denoted as the first polarization component light, but will not respond to the second polarization component light which is perpendicular to the polarization direction of the first polarization component light, resulting in a waste of energy of the second polarization component light. Figure 8This is a cross-sectional view of the diffraction waveguide light transmission in a display device employing an output element with a single polarization response and a polarization conversion element corresponding to the position of the output element, as provided in an embodiment of this application. By adding a polarization conversion element (PT) at the position corresponding to the output element on the optical waveguide, the second polarization component light, which cannot be coupled out by the output element, is converted into a first polarization component light that can be coupled out, thereby achieving the coupled output of all image light rays, improving light energy utilization efficiency, and thus improving the image brightness of the display system. In the implementation, the first polarization component light is linearly polarized light with a preset polarization direction, and the second polarization component light is linearly polarized light with a polarization direction perpendicular to the polarization direction of the first polarization component light. The polarization conversion element is an element with a birefringence effect. The polarization conversion element includes at least one layer of birefringent coating or birefringent film.

[0049] It should be noted that Figure 7(b) and Figure 8 The diagram only shows the case where the guided light (B2) is coupled out twice by the output element; the polarization conversion and coupling output shown are special cases. In actual operation, the output element may couple the guided light out dozens or even hundreds of times. For the case shown in Figure 7(b) without the polarization conversion element, as the guided light continuously interacts with the output element, the first polarization component decreases, while the second polarization component remains unchanged. Figure 8 In the scenario shown, due to the presence of the polarization conversion element, the second polarization component light that is not coupled out in the transmitted light is continuously converted into the first polarization component light that can be coupled out, ultimately achieving the coupling of all transmitted light energy into the first polarization component light output.

[0050] A polarization conversion element is placed on the optical waveguide at a position corresponding to the output element (DOE3). The position of the polarization conversion element is not limited; it can be located on the first principal plane, the second principal plane, or within the waveguide plate. For ease of fabrication, a preferred embodiment is that the polarization conversion element (PT) can be located on a second principal plane (S2) of the waveguide plate, different from the first principal plane (S1) where the output element is located, as described above. Figure 8 As shown in Figure 9(a), a schematic diagram of a polarization conversion element located on the first main plane of the waveguide plate where the output element is located, according to an embodiment of this application. Using the method shown in Figure 9(a), since the output element, i.e., the exit pupil grating, itself has a depolarization effect, the fabrication process can be simplified. Figure 9(b) is a schematic diagram of a polarization conversion element located within the waveguide plate according to an embodiment of this application. The polarization conversion element covers the waveguide substrate area where the output element is located, but does not cover the waveguide substrate area where the input element is located.

[0051] This embodiment provides a display device comprising: an image generation unit and an optical waveguide unit. The optical waveguide unit includes a waveguide substrate and an input element. The waveguide substrate includes a first principal plane and a second principal plane. The image generation unit generates a first input light carrying image information. The input element couples the first input light into the waveguide substrate, forming guided light that propagates back and forth between the first and second principal planes via total internal reflection within the waveguide substrate. The optical waveguide unit further includes: an output element with a single polarization response and a polarization conversion element. The polarization conversion element is located within the first principal plane, the second principal plane, or the waveguide substrate, and is used to convert a second polarization component of the guided light, which is different from the first polarization component, into a first polarization component. The output element expands and couples the first polarization component of the guided light, forming a first output light. In this display device, through the output element and the polarization conversion element with a single polarization response, the polarization conversion element converts the second polarization component that cannot be coupled out by the output element into the first polarization component that can be coupled out, achieving the coupling output of all image light rays, improving light energy utilization efficiency, and thus improving the image brightness of the display system.

[0052] Based on the above embodiments, in order to facilitate the user to receive the first output light, a preferred embodiment is that the display device further includes: a transparent substrate; the transparent substrate is used to receive and reflect the first output light to form a second output light for the user to observe.

[0053] The transparent substrate is used for the windshield of vehicles. Projecting important information needed by the driver onto the windshield can improve driving safety.

[0054] Since the reflectivity of windshield to incident S-polarized light is significantly higher than that of P-polarized light, in order to improve the overall optical transmission efficiency of the display system, a preferred embodiment is that the single polarization image is S-polarized light incident on the windshield, that is, the first output light is incident on the transparent substrate, and the electric vector direction of the first output light is perpendicular to the first incident surface. The first incident surface is jointly determined by the straight line in the propagation direction of the first output light and the straight line in the normal direction of the transparent substrate.

[0055] The foregoing provides a display device, and this embodiment also provides a vehicle, including the display device described above. The embodiments of the display device have been described in detail above, and the embodiments of the vehicle will not be repeated here, but have the same beneficial effects as the display device mentioned above.

[0056] The above provides a display device and a vehicle. This embodiment also provides an imaging method for outputting a single-polarization image light, applied to a display device including an image generation unit and an optical waveguide unit. The optical waveguide unit includes a waveguide substrate and an input element. The waveguide substrate includes a first principal plane and a second principal plane. The optical waveguide unit further includes: an output element having a single polarization response and a polarization conversion element. The method includes:

[0057] Acquire the guided light; wherein the guided light is the first input light carrying image information generated by the image generation unit coupled to the waveguide substrate through the input element, forming light that propagates between the first principal plane and the second principal plane of the waveguide substrate in a total internal reflection manner;

[0058] The second polarization component light, which is different from the first polarization component light, is converted into the first polarization component light by a polarization conversion element located in the first principal plane, the second principal plane, or the waveguide substrate.

[0059] The first output light is formed by expanding and coupling the first polarization component of the light through an output element with a single polarization response.

[0060] The imaging method for outputting a single polarized image light provided in this embodiment has the same technical features as the display device mentioned above. The embodiments of the display device have been described in detail above, and the embodiments of the imaging method for outputting a single polarized image light will not be repeated here.

[0061] The imaging method for outputting single-polarized image light provided in this embodiment employs an output element with single-polarization response characteristics, and constructs a polarization conversion element on the optical waveguide at a position corresponding to the output element. This polarization conversion element can continuously convert image light that cannot be responded to by the output element into a polarization state that can be responded to by the output element, and then be continuously diffracted multiple times by the output element, ultimately achieving a single-polarization output of all image light rays transmitted through the optical waveguide. This single polarization state can be controlled to be an S-polarization state with high reflectivity, thereby improving the overall optical transmission efficiency of the display system.

[0062] The foregoing has provided a detailed description of a display device, a vehicle, and an imaging method for outputting a single-polarized image light, as provided in this application. The various embodiments in the specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. It should be noted that those skilled in the art can make various improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

[0063] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A display device, comprising: An image generation unit and an optical waveguide unit are provided. The optical waveguide unit includes a waveguide substrate and an input element. The waveguide substrate includes a first principal plane and a second principal plane. The image generation unit is used to generate a first input light carrying image information. The input element is used to couple the first input light into the waveguide substrate to form a guided light that propagates back and forth between the first principal plane and the second principal plane in a total internal reflection manner within the waveguide substrate. The optical waveguide unit further includes an output element with a single polarization response and a polarization conversion element. The polarization conversion element is located in the first main plane, the second main plane, or the waveguide substrate, and is used to convert the second polarization component light, which is different from the first polarization component light, into the first polarization component light in the transmitted light. The output element is used to expand and couple the first polarization component of the guided light to form a first output light; thereby achieving the coupled output of all image light rays, improving the light energy utilization efficiency, and thus improving the image brightness of the display system. The polarization conversion element covers the waveguide substrate area where the output element is located, but does not cover the waveguide substrate area where the input element is located.

2. The display device according to claim 1, characterized in that, The display device further includes: a transparent substrate; the transparent substrate is used to receive and reflect the first output light to form a second output light for user observation.

3. The display device according to claim 2, characterized in that, The transparent substrate is the windshield of a vehicle.

4. The display device according to claim 1, characterized in that, The first polarization component light is linearly polarized light with a preset polarization direction, and the second polarization component light is linearly polarized light with a polarization direction perpendicular to the polarization direction of the first polarization component light.

5. The display device according to claim 1, characterized in that, The first output light is incident on a transparent substrate, and the electric vector direction of the first output light is perpendicular to the first incident surface. The first incident surface is jointly determined by a straight line in the propagation direction of the first output light and a straight line in the normal direction of the transparent substrate.

6. The display device according to claim 1, characterized in that, The polarization conversion element includes at least one birefringent coating or birefringent film layer.

7. The display device according to any one of claims 1 to 6, characterized in that, The polarization conversion element is an element with birefringence effect.

8. A means of transportation, characterized in that, Includes the display device according to any one of claims 1 to 7.

9. An imaging method for outputting a single-polarization image light, applied to a display device comprising an image generation unit and an optical waveguide unit, wherein the optical waveguide unit comprises a waveguide substrate and an input element, the waveguide substrate comprising a first main plane and a second main plane, and the optical waveguide unit further comprising: An output element and a polarization conversion element having a single polarization response; the polarization conversion element covers the waveguide substrate region where the output element is located, but does not cover the waveguide substrate region where the input element is located; characterized in that the method includes: Acquire guided light; wherein, the guided light is light that is coupled to the waveguide substrate by the first input light carrying image information generated by the image generation unit through the input element, and propagates between the first principal plane and the second principal plane of the waveguide substrate in a total internal reflection manner; The second polarization component light, which is different from the first polarization component light, is converted into the first polarization component light by a polarization conversion element located in the first main plane, the second main plane, or the waveguide substrate. The first polarization component of the transmitted light is expanded and coupled out by the output element having a single polarization response to form a first output light; thereby realizing the coupled output of all image light rays, improving the light energy utilization efficiency, and thus improving the image brightness of the display system.

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