Waveguide directional head-up display system

Abstract

The application discloses a waveguide directional head-up display system, comprising a light source, at least one waveguide substrate, a direction control element, a diffusion element, a transmissive display panel and a transreflective device, wherein the transreflective device reflects the light emitted by the transmissive display panel to a predetermined area. The light emitted by the light source is output through the waveguide substrate, so that the volume of the head-up display system can be greatly reduced. Meanwhile, the collimated light is adjusted to be gathered to a specified area by the direction control element, and the gathered light is expanded by the diffusion element. In a small volume, sufficient brightness can be ensured, so that the imaging effect is ensured while the volume of the HUD is reduced.

Description

Technical Field

[0001] This invention belongs to the field of optical display technology, and specifically relates to a waveguide directional head-up display system. Background Technology

[0002] HUD (head-up display) uses reflective optical design to project the light emitted from the image source onto an imaging window (image panel, windshield, etc.), allowing the driver to see the image directly without looking down. This avoids distraction caused by looking down at the instrument panel while driving, improves driving safety, and also provides a better driving experience.

[0003] Specifically, taking a HUD based on reflection imaging using plane and curved mirrors as an example, the light emitted from the HUD image source is reflected sequentially by the plane mirror and the curved mirror before exiting. The exiting light can be reflected on the transparent imaging window and retained on one side of the cockpit before entering the driver's eyes. This light entering the driver's eyes allows the driver to see a virtual image of the picture displayed on the HUD image source in the space on the other side of the imaging window. At the same time, because the imaging window itself is transparent, ambient light from the other side of the imaging window can still pass through it and reach the driver's eyes, so that the driver can see the HUD image without affecting their observation of the road conditions outside the vehicle.

[0004] However, due to the limited design space in automobiles, components need to compromise with each other, which brings many difficulties to the design of automotive components. As one of the components placed in the control panel, reducing the space occupied by the HUD is a very important design consideration. At present, HUDs usually use LCD screens with LED lamps as the image source to generate images. Due to their large thickness, the size of the HUD is limited, which also limits the further promotion and application of HUDs. Summary of the Invention

[0005] To overcome the problem of large image source thickness in existing technologies, this invention provides a waveguide-oriented head-up display system.

[0006] An embodiment of the present invention provides a waveguide-oriented head-up display system, comprising:

[0007] A waveguide-oriented head-up display system, characterized in that it comprises:

[0008] A light source, wherein the narrowband input light emitted by the light source is input into the at least one waveguide substrate;

[0009] At least one waveguide substrate, the at least one waveguide substrate including a light extraction element and an optical waveguide medium, the optical waveguide medium transmitting narrowband input light emitted by the light source to the light extraction element, the light extraction element outputting the light transmitted to the light extraction element via the optical waveguide medium from different positions of the waveguide substrate in a predetermined output direction;

[0010] The direction control element receives light rays and adjusts the principal optical axis direction of the light rays at each position to converge them into a designated area.

[0011] A diffusion element receives light and diffuses the received light at a preset diffusion angle deviating from the direction of the principal optical axis;

[0012] Transmissive display panels receive light and transmit light to form an image;

[0013] A reflective device reflects the light transmitted from the transmissive display panel back to the predetermined area.

[0014] Optionally, a pre-collimation element is also provided between the light source and the waveguide substrate, and the narrowband input light emitted by the light source is input to the at least one waveguide substrate after passing through the pre-collimation element.

[0015] Optionally, the pre-collimation element includes at least one of a convex lens, a Fresnel lens, a mirror, and a lens combination.

[0016] Optionally, the narrowband input light emitted by the light source has at least one spectral band in the visible light band, and the full width at half maximum (FWHM) of the spectral band is less than or equal to 60 nm.

[0017] Optionally, the narrowband input light emitted by the light source has at least one of a red spectral band, a green spectral band, and a blue spectral band in the visible light band.

[0018] Optionally, an optical coupling element is further included between the light source and the waveguide substrate, the optical coupling element coupling the narrowband input light emitted by the light source into the optical waveguide medium.

[0019] Optionally, the input light is a beam array, which propagates in the optical waveguide medium along the first total internal reflection propagation direction to the light extraction element;

[0020] The light extraction element expands the beam array into a beam surface array in the first total internal reflection propagation direction and outputs it from the waveguide substrate.

[0021] Optionally, the input light is a single beam, and the waveguide substrate further includes an intermediate beam expander. The intermediate beam expander expands the single beam in the optical waveguide medium along the second total internal reflection propagation direction to form a beam array, and guides the beam array to the light extraction element.

[0022] The light extraction element expands the beam array into a beam surface array in the first total internal reflection propagation direction and outputs it from the waveguide substrate.

[0023] Optionally, the preset output direction is the normal direction of the total internal reflection transmission surface of the waveguide substrate.

[0024] Optionally, the preset output direction is a direction in which the preset angle between the output direction and the normal direction of the total internal reflection surface of the waveguide substrate is greater than 0° and less than 90°.

[0025] Optionally, the waveguide substrate is a single unit, and the waveguide substrate includes at least one of the light extraction elements. Each light extraction element outputs light rays from the narrowband input light emitted by the light source that correspond to the spectral band of its characteristic parameters in a predetermined direction.

[0026] Optionally, there are at least two waveguide substrates, each waveguide substrate containing at least one light extraction element, the light extraction element outputting the narrowband input light emitted by the light source from the waveguide substrate in a predetermined direction.

[0027] Optionally, the at least two waveguide substrates are stacked in a direction perpendicular to the substrate.

[0028] Optionally, the light extraction element includes a surface grating or a volume grating.

[0029] Optionally, the orientation control element includes at least one of a convex lens, a sawtooth lens, a Fresnel lens, and a lens combination.

[0030] Optionally, the diffusion element is used to expand the light beam into a beam with a specific shape in the cross-section perpendicular to the principal optical axis.

[0031] Optionally, the beam of the specific shape covers the predetermined area.

[0032] Optionally, the diffusion element is a diffractive optical element.

[0033] Optionally, the transmissive display panel includes a liquid crystal layer, the liquid crystal layer includes liquid crystal cells and a first polarization unit and a second polarization unit disposed on both sides of the liquid crystal cells, the first polarization unit and the second polarization unit having different polarization directions.

[0034] Optionally, the head-up display system may also include at least one reflective element.

[0035] In the above-described solution provided by the embodiments of the present invention, the light emitted by the light source is input into the waveguide substrate. The light undergoes total internal reflection in the optical waveguide medium of the waveguide substrate and is thus propagated in the waveguide substrate. The light propagating in the optical waveguide medium is emitted from different positions of the waveguide substrate in a predetermined direction by the light extraction element in the waveguide substrate and output to the display panel. This eliminates the need for a lamp cup, thereby reducing the size of the head-up display system.

[0036] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0037] Figure 1 This diagram illustrates the structure of a waveguide-oriented head-up display system according to an embodiment of the present invention. Figure 1 ;

[0038] Figure 2a This diagram shows a partial structural schematic of a waveguide-oriented head-up display system according to an embodiment of the present invention. Figure 1 ;

[0039] Figure 2b A partial structural schematic diagram of a waveguide-oriented head-up display system according to an embodiment of the present invention is shown in Figure 2.

[0040] Figure 3 A schematic diagram of the diffusion of light by a diffusion element according to an embodiment of the present invention is shown;

[0041] Figure 4a This diagram shows a partial structural schematic of a waveguide-oriented head-up display system according to an embodiment of the present invention. Figure 3 ;

[0042] Figure 4b A partial structural schematic diagram of a waveguide-oriented head-up display system according to an embodiment of the present invention is shown in Figure 4.

[0043] Figure 5 This diagram illustrates the structure of a waveguide-oriented head-up display system according to an embodiment of the present invention. Figure 3 ;

[0044] Figure 6 This shows a schematic diagram of the structure of a waveguide-oriented head-up display system according to an embodiment of the present invention;

[0045] Figure 7 A schematic diagram showing the output light of a light extraction element according to an embodiment of the present invention is displayed;

[0046] Figure 8 A schematic diagram of the beam amplification of light by an intermediate beam expander element in one embodiment of the present invention is shown;

[0047] Figure 9aThis diagram shows a partial structural schematic of a waveguide-oriented head-up display system according to an embodiment of the present invention. Figure 5 ;

[0048] Figure 9b This diagram shows a partial structural schematic of a waveguide-oriented head-up display system according to an embodiment of the present invention. Figure 6 ;

[0049] Figure 9c This diagram shows a partial structural schematic of a waveguide-oriented head-up display system according to an embodiment of the present invention. Figure 7 ;

[0050] Figure 10a This diagram shows a partial structural schematic of a waveguide-oriented head-up display system according to an embodiment of the present invention. Figure 8 ;

[0051] Figure 10b A partial structural schematic diagram of a waveguide-oriented head-up display system according to an embodiment of the present invention is shown in Figure 9.

[0052] Figure 10c A partial structural schematic diagram of a waveguide-oriented head-up display system according to an embodiment of the present invention is shown.

[0053] Figure 10d A partial structural schematic diagram of a waveguide-oriented head-up display system according to an embodiment of the present invention is shown in Figure 11.

[0054] Figure 11a This illustration shows a narrowband input photosynthesis according to an embodiment of the present invention. Figure 1 ;

[0055] Figure 11b A schematic diagram of narrowband input photosynthesis according to an embodiment of the present invention is shown in Figure 2.

[0056] Figure 11c This illustration shows a narrowband input photosynthesis according to an embodiment of the present invention. Figure 3 ;

[0057] Figure 12a This is illustrated in Figure 12, a partial structural schematic diagram of a waveguide-oriented head-up display system according to an embodiment of the present invention.

[0058] Figure 12b This is illustrated in Figure 13, a partial structural schematic diagram of a waveguide-oriented head-up display system according to an embodiment of the present invention.

[0059] Figure 12c This diagram shows a partial structural schematic of a waveguide-oriented head-up display system according to an embodiment of the present invention.

[0060] Figure 12d Figure 15 shows a partial structural schematic diagram of a waveguide-oriented head-up display system according to an embodiment of the present invention.

[0061] Labeling Explanation: 100-Light source; 200-Waveguide substrate; 210-Light extraction element; 220-Optical waveguide medium; 300-Direction control element; 400-Diffusivity element; 500-Liquid crystal layer; 600-Transmission and reflection device; 700-Pre-collimation element; 800-Light combining element; 230-Optical coupling element; 240-Intermediate beam expander element; 101-Narrowband red light; 102-Narrowband green light; 103-Narrowband blue light. Detailed Implementation

[0062] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0063] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0064] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0065] It should be noted that, for the sake of brevity and intuitiveness, the following description uses several representative embodiments to illustrate the solution of the present invention. Numerous details in the embodiments are only used to aid in understanding the solution of the present invention. However, it is obvious that the technical solution of the present invention may not be limited to these details. To avoid unnecessarily obscuring the solution of the present invention, some embodiments are not described in detail, but only a framework is given. In the following text, "comprising" means "including but not limited to," and "according to..." means "at least according to..., but not limited to only according to...". "First," "second," etc., are used only to refer to features and are not intended to impose any limitations on the feature, such as restrictions on order. Due to Chinese language habits, unless the quantity of a component is specifically indicated below, it means that the component can be one or more, or can be understood as at least one.

[0066] This embodiment provides a waveguide head-up display system; see [link / reference] Figure 1 As shown, it includes:

[0067] A light source 100 emits narrowband input light which is input into at least one waveguide substrate 200. The at least one waveguide substrate 200 includes a light extraction element 210 and an optical waveguide medium 220. The optical waveguide medium 220 transmits the narrowband input light emitted by the light source 100 to the light extraction element 210. The light extraction element 210 outputs the light transmitted via the optical waveguide medium 220 from different positions on the waveguide substrate 200 in a predetermined output direction. A direction control element 300 receives the light and adjusts the principal optical axis direction of the light at each position to converge it into a designated area. A diffusion element 400 receives the light and diffuses the received light at a predetermined diffusion angle deviating from the principal optical axis direction. A transmissive display panel 500 receives the light and transmits light for forming an image. A transflective device 600 reflects the light transmitted from the transmissive display panel 500 to the predetermined area.

[0068] In this embodiment, the narrowband input light emitted by the light source 100 has at least one spectral band in the visible light band. Specifically, a spectral band refers to the wavelength spectral band of the narrowband input light emitted by the light source, such as a wavelength spectral band of 550nm-600nm. Narrow band specifically refers to a spectral band with a full width at half maximum (FWHM) of less than or equal to 60nm, preferably less than or equal to 30nm, and more preferably less than or equal to 10nm. In this embodiment, the narrowband input light emitted by the light source 100 may specifically include at least one spectral band, such as a first spectral band with a peak position in the range of 400nm-470nm, a second spectral band with a peak position in the range of 500nm-580nm, and a third spectral band with a peak position in the range of 590nm-690nm. It is understood that narrowband input light with a single spectral band is monochromatic light, while narrowband input light with multiple spectral bands is polychromatic light. To enable the HUD to display a color image, it is preferable that the light source 100 emits narrowband input light with three spectral bands, namely blue, green, and red light. In a preferred embodiment, the narrowband input light emitted by the light source 100 may include three colors: red, green, and blue, located in the wavelengths of 630nm±10nm (red), 540nm±10nm (green), and 450nm±10nm (blue).

[0069] Optionally, the light source 100 may be a monochromatic light-emitting diode (LED) light source, including but not limited to red LEDs, green LEDs, blue LEDs, and gallium arsenide diodes emitting red light, gallium phosphide diodes emitting green light, silicon carbide diodes emitting yellow light, and gallium nitride diodes emitting blue light. The light source 100 may also be a white light-emitting diode emitting RGB or blue light, including but not limited to LEDs that use blue light to excite phosphors to form white light, or LEDs that mix multiple monochromatic lights such as red, green, and blue light to form white light. The light source 100 may also be a laser light source, including but not limited to lasers emitting red light, lasers emitting green light, and lasers emitting blue light; this embodiment does not limit this.

[0070] Narrowband input light emitted from the light source 100 is output from different positions of the waveguide substrate 200 in a predetermined output direction via at least one waveguide substrate 200. Specifically, see [link to relevant documentation]. Figure 1 As shown in Figure 2, taking a waveguide substrate 200 as an example, the narrowband input light emitted by the light source 100 is incident into the waveguide substrate 200 at a suitable angle. The waveguide substrate 200 includes an optical waveguide medium 200, that is, the narrowband input light propagates within the optical waveguide medium 200 according to the principle of total internal reflection (e.g., ...). Figure 1 As shown by the broad arrow in Figure 2, when the narrowband input light propagates to the light extraction element 210, the light extraction element 210 can output the narrowband input light from different positions on the waveguide substrate 200 in a predetermined output direction. It can be understood that there are many different positions on the waveguide substrate 200, such as... Figure 1 The output is shown in five different positions, with positions A, B, and C used for illustrative purposes in the diagram. Specifically, as shown... Figure 2a As shown, the narrow-band input light emitted by the light source 100 exits along the normal direction of the total internal reflection inner surface. Figure 2a The inner surface of the total internal reflection is the upper surface of the waveguide substrate 200. In this case, the predetermined output direction is perpendicular to the waveguide substrate 200, and the output light is collimated. This direction can also be a direction with a predetermined angle of 0° and less than 90° between it and the normal direction of the total internal reflection surface of the waveguide substrate 200, such as... Figure 2b As shown, there is an angle θ between the predetermined output direction and the normal, where θ∈(0,90), specifically 30°, 45° or 60°. In this case, the output light is a collimated light with a certain tilt angle.

[0071] Optionally, the light extraction element 210 includes a surface grating or a volumetric grating. The light extraction element 210 can diffract the light transmitted by the optical waveguide medium 220 out of the waveguide substrate 200 in a predetermined output direction. Specifically, the light diffracts on the light extraction element 210, thereby breaking the total internal reflection condition. The light no longer propagates through total internal reflection and is thus emitted parallel from the waveguide substrate 200. The waveguide substrate 200 is made of a material that can realize waveguide function, including but not limited to silicon dioxide, lithium niobate, silicon-on-insulator (SOI), polymer, III-V semiconductor compounds, and glass. The waveguide substrate 200 can be a planar substrate, a strip substrate, or a ridge substrate; this embodiment does not limit this.

[0072] The direction control element 300 receives light and adjusts the main optical axis direction of the light at each position to converge towards the specified area. Specifically, the light output after passing through the waveguide substrate 200 can be sent to the direction control element 300. Figure 1 The diagram provides the principal ray (CR) for light rays at three different positions: A, B, and C, labeled CRA, CRB, and CRC, respectively. The principal ray specifically refers to the direction in which the light ray emitted from that position is strongest, typically located at the center. For example... Figure 1 As shown, before the light reaches the direction control element 300, the principal optical axis is perpendicular to the waveguide substrate. After passing through the direction control element 300, the CRA, CRB, and CRC all change direction and converge towards the designated area, which is the... Figure 1 The intersection of the extensions of the dashed lines CRA, CRB, and CRC (not shown in the figure). It should be understood that the designated area in this embodiment does not represent a single point, but could also be a smaller region. Figure 1 The diagram schematically illustrates a direction control element 300. Those skilled in the art will understand that the number of direction control elements 300 can be multiple, and each direction control element 300 can adjust the direction of light output from a portion of the waveguide substrate 200. This embodiment does not limit this. Specifically, the direction control element 300 can be a Fresnel lens, a convex lens, a sawtooth lens (such as a sawtooth cylindrical lens or a sawtooth Fresnel lens), or a lens combination (such as a combination of a convex lens and a concave lens, or a combination of a Fresnel lens and a concave lens). For example, if the direction control element 300 is a convex lens, then the designated area A is the focal point of the convex lens. Optionally, the direction control element 300 can also be a photonic crystal, which can focus light at a specific angle and in a specific manner.

[0073] The diffusion element 400 receives light and diffuses it at a preset diffusion angle deviating from the chief ray direction. Specifically, the light can be focused by the direction control element 300 and then diffused by the diffusion element. Focused light can only form an image within a very small area, making it inconvenient for the observer to view the image projected by the HUD. The diffusion element 400 diffuses the received light at a preset diffusion angle deviating from the chief ray direction. Figure 1 The diagram simply illustrates the beam-expanding effect of the scattering element 400 on light rays. When the scattering element 400 is absent, the light rays emitted from the three different positions A, B, and C still follow the principal optical axis at their corresponding positions (i.e., Figure 1 The dotted lines (CRA, CRB, CRC) propagate in the image. Figure 1 In the diagram, the principal optical axis of the light ray emitted from position A is shown by CRA, the principal optical axis of the light ray emitted from position B is shown by CRB, and the principal optical axis of the light ray emitted from position C is shown by CRC. Figure 1 The diagram schematically illustrates that the direction of the main optical axis changes after being controlled by the direction control element 300. Figure 1 In some practical applications not shown, the diffusion element 400 can also simultaneously possess certain directional control and diffusion properties. For example, it can separate the received light into two beams along the original principal optical axis, thereby diffusing them in the two separated principal optical axis directions. Adding the diffusion element 400 diffuses the light in a direction deviating from the principal optical axis, diffusing it into light with a certain degree of divergence, such as... Figure 1 The CRA, CRB, and CRC axes show the light rays at the diffused edges. In this embodiment, the diffusion element 400 diffuses the light, forming a beam of a preset shape with a larger imaging range, thus facilitating viewing of the HUD image over a wider area. It can be understood that the diffusion element 400 not only expands the light beam but also makes the light distribution more uniform within the preset diffusion angle. Figure 1 This embodiment describes the use of one diffusing element 400, but the number of diffusing elements 400 can also be multiple. Using multiple diffusing elements 400 will result in a more uniform light distribution, but this embodiment does not limit this. Those skilled in the art will understand that... Figure 1 The diffusion effect of the diffusion element 400 is only illustrative. The diffusion element 400 can expand the light beam to a preset diffusion angle range, but does not completely restrict the light beam to the preset diffusion angle range.

[0074] Optionally, the diffusion element 400 is used to expand the light beam into a beam with a specific shape in the cross section perpendicular to the principal optical axis. The size and shape of the cross section are determined by the microstructure of the diffusion element 400. The preset shape of the cross section includes, but is not limited to, a circle, an ellipse, a square, a rectangle, and a batwing shape. Figure 3The diagram illustrates the beam pattern using a rectangular cross-section. After light ray A passes through the diffusing element 400, rays A1, A2, A3, and A4 are located at the expanded edge of the beam. The diffusing element 400 expands the beam and deflects it along the principal optical axis A', resulting in a rectangular cross-section perpendicular to A'. The diffusing element 400 can specifically be a diffractive optical element (DOE), such as a beam shaper. Optionally, the diffused beam has a 10-degree angle of dispersion in the side-view direction, preferably 5 degrees; and a 50-degree angle of dispersion in the front-view direction, preferably 30 degrees. The diffusing element can be located above or below the transmissive display panel.

[0075] It is understood that the beam of light of a specific shape formed after diffusion by the diffusion element 400 is finally reflected by the transflection device 600, and the beam covers the predetermined area, ensuring that a complete image can be viewed within the predetermined area. Optionally, the beam can completely cover the predetermined area, that is, the cross-sectional area of ​​the beam at the predetermined area coincides with the predetermined area; or a portion of the beam covers the predetermined area, that is, the cross-sectional area of ​​the beam at the predetermined area covers and is larger than the predetermined area. This embodiment does not impose any restrictions on this.

[0076] The transmissive display panel 500 receives light and transmits light for forming an image. Specifically, the expanded light beam passes through the transmissive display panel and then emits light for forming an image. After reflection by the transflection-reflection device 600, the HUD image can be observed. In this embodiment, the transmissive display panel can be a liquid crystal layer, which includes liquid crystal cells and a first polarization unit and a second polarization unit disposed on both sides of the liquid crystal cells. The polarization directions of the first polarization unit and the second polarization unit are different. The liquid crystal cell can be a common liquid crystal, such as a twisted nematic (TN) liquid crystal, a high twisted nematic (HTN) liquid crystal, a super twisted nematic (STN) liquid crystal, a formatted super twisted nematic (FSTN) liquid crystal, etc. The liquid crystal cell can also be a blue phase liquid crystal. The first polarization unit can be a horizontal linear polarizer, and the second polarization unit can be a vertical linear polarizer; or the first polarization unit can be a vertical linear polarizer, and the second polarization unit can be a horizontal linear polarizer; or the first polarization unit can be a left-handed circular polarizer, and the second polarization unit can be a right-handed circular polarizer; or the first polarization unit can be a right-handed circular polarizer, and the second polarization unit can be a right-handed or left-handed circular polarizer; or the first polarization unit can be a left-handed elliptical polarizer, and the second polarization unit can be a right-handed elliptical polarizer; or the first polarization unit can be a right-handed elliptical polarizer, and the second polarization unit can be a left-handed elliptical polarizer. This embodiment does not limit this.

[0077] like Figure 1 As shown, light is reflected into a predetermined area after reaching the reflective device 600. In this embodiment, the reflective device is a device that can simultaneously realize the functions of light transmission and reflection. Specifically, it can be a transparent material, such as ordinary glass, quartz glass, automotive windshield, and transparent resin plate, preferably a windshield. The observer can observe the virtual image formed by the HUD through the windshield, and can also observe the external environment. The predetermined area can specifically be the eyebox area, which refers to the area where the observer can see the complete image of the HUD. Figure 1 The example given is a pre-defined area. It can be understood that there can be multiple pre-defined areas, each corresponding to a different eye box area, allowing for observation from multiple perspectives.

[0078] It is understood that this embodiment uses the waveguide substrate 200, direction control element 300, diffusion element 400, and transmissive display panel 500 arranged sequentially as an example to explain the technical solution of the present invention, but it does not mean that the present invention limits the positional relationship of the waveguide substrate 200, direction control element 300, diffusion element 400, and transmissive display panel 500. Figure 4a As shown, a waveguide substrate 200, a transmissive display panel 500, a direction control element 300, and a diffusion element 400 can be sequentially arranged; for example... Figure 4b As shown, a waveguide substrate 200, a direction control element 300, a transmissive display panel 500, and a diffusion element 400 can be sequentially arranged. The components can be arranged separately, or they can be tightly or partially tightly attached; none of these arrangements affect the realization of the technical solution of this invention.

[0079] This embodiment provides a waveguide-oriented head-up display system. By collimating the light emitted from the light source through the waveguide substrate, the size of the head-up display system can be greatly reduced. At the same time, the direction control element focuses the collimated light from different positions to a designated area, which can improve the light brightness. Meanwhile, the light beam is expanded by the diffusion element, so that imaging can be performed over a larger area. While improving the light brightness, the imaging range can also be expanded, thus ensuring the imaging effect while reducing the overall size of the HUD.

[0080] Based on the various embodiments of the present invention, in order to further improve the light efficiency, a pre-collimation element 700 is further provided between the light source 100 and the waveguide substrate 200, such as... Figure 5 As shown. The pre-collimation element 700 can adjust the direction of the narrowband input light emitted by the light source 100. Figure 5Taking the pre-collimation element 700 as an example of collimating light, the light source 100 is a point light source. The light emitted from the point light source is dispersed within a certain range, and only light at a predetermined angle can enter the waveguide substrate 200 to meet the total internal reflection condition and be conducted. Therefore, the pre-collimation element 700 pre-collimates the dispersed light within a certain angle range, such as ±5°, ±10°, or ±30°. In this way, most of the light can meet the preset angle condition for entering the waveguide substrate 200, improving the utilization rate of light. In this embodiment, the pre-collimation element 700 can specifically be at least one of a convex lens, a Fresnel lens, a reflector, and a lens combination. The lens combination can specifically be a combination of a convex lens and a concave lens, a combination of a Fresnel lens and a concave lens, etc.; or, the pre-collimation element 700 is a collimation film used to adjust the outgoing direction of light to within the preset angle range.

[0081] Based on the various embodiments of the present invention, such as Figure 6 As shown, the waveguide-oriented head-up display system also includes an optical coupling element 230. The figure illustrates this with an example of the optical coupling element being mounted on the waveguide element 200. The optical coupling element 230 couples the narrowband input light emitted from the light source 100 into the optical waveguide medium 220. Specifically, it adjusts the angle of the light beam to meet the total internal reflection condition of the optical waveguide medium 220 for transmission. Figure 6 As indicated by the dashed arrow in the middle. Specifically, the optical coupling element 230 can be at least one of a surface grating, a volume grating, a blazed grating, a prism, and a reflective structure. It couples the narrow-band input light emitted by the light source 100 into the optical waveguide medium through at least one of the effects of reflection, refraction, and diffraction, so that it satisfies the condition of total internal reflection and is then conducted.

[0082] Based on the various embodiments of the present invention, such as Figure 7 As shown, the input light is a beam array. A beam is a collection of parallel light rays that has a certain cross-sectional area on a section perpendicular to the direction of light propagation and that has equal light intensity on the section. Figure 7 Top view of waveguide element 200 (relative to) Figure 1 To illustrate, consider a beam array distributed along a one-dimensional direction. The coupled light rays are guided in the optical waveguide medium 220 along the first total internal reflection propagation direction (direction A in the figure) to the light extraction element 210. The light extraction element 210 expands the beam array into a beam surface array on the first total internal reflection propagation surface and outputs it from the waveguide substrate 200. This achieves beam expansion of the one-dimensional beam array, that is, expanding the beam array into a beam surface array and outputting it from the waveguide substrate 200. Specifically, a light source emitting the beam array, such as a line light source, can be transformed into a surface light source by the light extraction element 210, allowing the light to be emitted uniformly over a large area.

[0083] Furthermore, the waveguide substrate 200 also includes an intermediate beam expander 240, which expands the single beam in the optical waveguide medium 220 along the second total internal reflection propagation direction to form a beam array and guides the beam array to the light extraction element 210. Figure 8 Top view of waveguide element 200 (relative to) Figure 1 Specifically, the intermediate beam expander 240 expands the single beam along the second total internal reflection propagation direction (direction B in the figure) into a beam array. The beam array expanded by the intermediate beam expander 240 propagates along the waveguide substrate 200 and exits when it reaches the light extraction element 210. The light extraction element 210 expands the beam array into a beam surface array along the first total internal reflection propagation direction and outputs it from the waveguide substrate 200. Through the combined action of the intermediate beam expander 240 and the light extraction element 210, a secondary beam expansion of the single beam is achieved, that is, the single beam is expanded into a beam surface array. Specifically, a light source emitting a single beam, such as a laser, can be transformed into a surface light source through the combined action of the intermediate beam expander and the light extraction element 210, allowing the light to be emitted uniformly over a large area.

[0084] Based on the various embodiments of the present invention, the number of waveguide substrates 200 may be one. Each waveguide substrate 200 includes at least one light extraction element 210. Each light extraction element outputs light rays from the narrowband input light emitted by the light source that correspond to the spectral band of its characteristic parameters in a predetermined direction. Specifically, when the light extraction element 210 is a surface grating or a volume grating, characteristic light rays satisfying at least one of its characteristic parameters, such as grating constant, grating frequency, and blaze wavelength, will be diffracted out of the waveguide substrate 200 by the light extraction element 200. For example... Figure 9a As shown, narrow-band input light of a single spectral band emitted by the light source 100 is diffracted off the waveguide substrate 200 on a light extraction element 200; as Figure 9b As shown, the narrowband input light emitted by the light source 100 includes red, blue, and green light, all of which can be diffracted on a light extraction element 200 and output in a predetermined direction; as Figure 9c As shown, the narrowband input light emitted by the light source 100 includes red light, blue light, and green light. The three types of light are diffracted on the light extraction element 200 corresponding to their characteristic parameters and output in a predetermined direction.

[0085] Based on various embodiments of the present invention, there may be at least two waveguide substrates 200, each waveguide substrate containing at least one light extraction element. The light extraction element directs the narrowband input light emitted by the light source onto the direction control element in a predetermined direction. Specifically, when the light extraction element 210 is a surface grating or a volume grating, it diffracts characteristic light rays satisfying at least one of its characteristic parameters, such as grating constant, grating frequency, and blaze wavelength, out of the waveguide substrate 200. For example... Figure 10aAs shown, the two narrowband input beams emitted by the light source 100 are diffracted and output on the light extraction element 210 corresponding to their characteristic parameters; as Figure 10b As shown, two narrowband lights emitted by light source 100 are diffracted and output on light extraction elements corresponding to their characteristic parameters, and another light emitted by light source 100 is diffracted and output on another light extraction element corresponding to its characteristic parameters. For example, red and green light in the narrowband input light are diffracted and output on one light extraction element 210 corresponding to its characteristic parameters (the upper light extraction element 210 in the figure), and blue light is diffracted and output on another light extraction element 210 corresponding to its characteristic parameters (the lower light extraction element 210 in the figure); Figure 10c As shown, the narrowband input light emitted by the light source 100 includes red, blue, and green light. These three light rays are combined into a single beam, which diffracts at the light extraction element 210 corresponding to its characteristic parameters and is output in a predetermined direction. Figure 10d As shown, the red light 101, green light 102, and blue light 103 in the narrowband input light emitted by the light source 100 can enter each waveguide substrate for conduction without beam combining, and be diffracted on the light extraction element 210 and output in a predetermined direction.

[0086] Based on the various embodiments of the present invention, by adding a light combining element 800, the light combining of at least two input lights emitted by the light source 100 can be achieved. See [link to relevant documentation]. Figure 11a As shown, green light 102 is transmitted through the light-combining element, and red light 101 is reflected by the light-combining element to achieve light combination; see [link / reference] Figure 11b As shown, the light combining element can specifically be a semi-transparent and semi-reflective device, a polarization reflective device, or a wavelength bandpass device. Green light 102 is transmitted through two light combining elements, red light 101 is reflected and transmitted through two light combining elements in sequence, and blue light 103 is reflected through one light combining element to achieve light combining. The light combining element can specifically be a semi-transparent and semi-reflective device, a polarization reflective device, or a wavelength bandpass device. Figure 11c In another implementation of the light combining element, blue light 101, green light 102 and red light 101 achieve light combining through the transmission and reflection of the light combining prism (X-cube).

[0087] Specifically, at least two waveguide substrates are stacked along a direction perpendicular to the substrates, as shown in Figures 9 and 10. The substrates can be tightly bonded or separated, and a vacuum can be maintained between the substrates, or a medium with a refractive index lower than that of the light extraction element, such as air, can be filled between them. In particular, when the light extraction element is a volume grating, multiple waveguide substrates can be tightly bonded and stacked; when the light extraction element is a surface grating, the substrates need to be separated. It can be understood that in this embodiment, the number and number of layers of light extraction elements, light coupling elements, and waveguide substrates are not particularly limited, as long as the light coupled into the waveguide substrate can undergo total internal reflection and be output in a predetermined direction by the light extraction element.

[0088] Based on the various embodiments of the present invention, optionally, when both the optical coupling element and the light extraction element are surface gratings, or both are volume gratings, the optical coupling element and the light extraction element can be transmissive or reflective gratings. Figure 12 illustrates an example where both the optical coupling element and the light extraction element are surface gratings. The optical coupling element can be a transmissive grating, and the light extraction element can be a transmissive grating, such as... Figure 12a As shown; the light extraction element can also be a reflective grating, such as Figure 12b As shown. The optical coupling element can be a reflective grating, and the light extraction element can also be a reflective grating, such as... Figure 12c As shown; the light extraction element 210 can also be a transmissive grating, such as Figure 12d As shown. When the light-coupled element is a surface grating and the light-extracting element is a volume grating, the light-coupled element can be a transmissive grating, and the light-extracting element can be a transmissive grating or a reflective grating; the light-coupled element can be a reflective grating, and the light-extracting element can be a reflective grating or a transmissive grating; when the light-coupled element is a volume grating and the light-extracting element is a surface grating, the light-coupled element can be a transmissive grating, and the light-extracting element can be a transmissive grating or a reflective grating; the light-coupled element can be a reflective grating, and the light-extracting element can be a reflective grating or a transmissive grating. This invention does not limit these possibilities.

[0089] Based on the various embodiments of the present invention, the waveguide-oriented head-up display system may further include at least one reflective element, which may be a plane mirror, a curved mirror, or a combination of mirrors. The reflective element is disposed between the transmissive display panel 500 and the transflection-reflection device 600. The reflective element is used to reflect the light emitted from the transmissive display panel 500 to the transflection-reflection device 600, and then to a predetermined area. Specifically, the curved mirror can expand the imaging area, allowing the head-up display to image over a large area of ​​the windshield even if the transmissive display panel area is small.

[0090] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A waveguide-oriented head-up display system, characterized in that, include: A light source, at least one waveguide substrate, a direction control element, a diffusion element, a transmissive display panel, and a transflective device; The narrowband input light emitted by the light source is input into the at least one waveguide substrate, and the narrowband input light emitted by the light source has a red spectral band, a green spectral band and a blue spectral band in the visible light band. The at least one waveguide substrate includes a light extraction element and an optical waveguide medium. The optical waveguide medium transmits narrowband input light emitted by the light source to the light extraction element. The light extraction element outputs collimated light rays from different positions on the waveguide substrate in a predetermined output direction. The narrowband input light includes red, blue, and green light rays, which are diffracted on the light extraction element corresponding to their respective characteristic parameters and output as collimated light rays in the predetermined output direction. The direction control element receives light and adjusts the main optical axis direction of the light at each position to converge towards a designated area; The diffusion element receives light and diffuses the received light at a preset diffusion angle deviating from the direction of the principal optical axis; The transmissive display panel receives light and transmits light for forming an image; The transflective device reflects the light transmitted by the transmissive display panel to a predetermined area; A pre-collimation element is also provided between the light source and the waveguide substrate. The narrowband input light emitted by the light source is input to the at least one waveguide substrate after passing through the pre-collimation element. Wherein, there is one waveguide substrate, the waveguide substrate includes at least one light extraction element, each light extraction element outputs light rays from the narrowband input light emitted by the light source that correspond to the spectral band of its characteristic parameters in a predetermined direction; or, there are at least two waveguide substrates, each waveguide substrate includes at least one light extraction element, the light extraction element outputs the narrowband input light emitted by the light source from the waveguide substrate in a predetermined direction, and the at least two waveguide substrates are stacked in a direction perpendicular to the substrate.

2. The waveguide directional head-up display system according to claim 1, characterized in that, The pre-collimation element includes at least one of a convex lens, a Fresnel lens, and a reflector.

3. The waveguide directional head-up display system according to claim 1, characterized in that, The full width at half maximum (FWHM) of the spectral band is less than or equal to 60 nm.

4. The waveguide directional head-up display system according to claim 1, characterized in that, Between the light source and the waveguide substrate, there is also an optical coupling element that couples the narrowband input light emitted by the light source into the optical waveguide medium.

5. The waveguide directional head-up display system according to claim 4, characterized in that, The input light is a beam array, which propagates to the light extraction element in the optical waveguide medium along the first total internal reflection propagation direction. The light extraction element expands the beam array into a beam surface array in the first total internal reflection propagation direction and outputs it from the waveguide substrate.

6. The waveguide directional head-up display system according to claim 4, characterized in that, The input light is a single beam, and the waveguide substrate further includes an intermediate beam expander. The intermediate beam expander expands the single beam in the optical waveguide medium along the second total internal reflection propagation direction to form a beam array, and guides the beam array to the light extraction element. The light extraction element expands the beam array into a beam surface array in the first total internal reflection propagation direction and outputs it from the waveguide substrate.

7. The waveguide directional head-up display system according to claim 1, characterized in that, The predetermined output direction is the normal direction of the total internal reflection transmission surface of the waveguide substrate.

8. The waveguide directional head-up display system according to claim 1, characterized in that, The predetermined output direction is a direction in which the angle between the predetermined output direction and the normal direction of the total internal reflection surface of the waveguide substrate is greater than 0° and less than 90°.

9. The waveguide directional head-up display system according to claim 1, characterized in that, The light extraction element includes a surface grating or a volume grating.

10. The waveguide directional head-up display system according to claim 1, characterized in that, The orientation control element includes at least one of a convex lens, a sawtooth lens, and a Fresnel lens.

11. The waveguide directional head-up display system according to claim 1, characterized in that, The diffusion element is used to expand the light beam into a beam with a specific shape in the cross-section perpendicular to the principal optical axis.

12. The waveguide directional head-up display system according to claim 11, characterized in that, The beam of light of a specific shape covers the predetermined area.

13. The waveguide directional head-up display system according to claim 1, characterized in that, The diffusion element is a diffractive optical element.

14. The waveguide directional head-up display system according to claim 1, characterized in that, The transmissive display panel includes a liquid crystal layer, which includes liquid crystal cells and a first polarization unit and a second polarization unit disposed on both sides of the liquid crystal cells. The first polarization unit and the second polarization unit have different polarization directions.

15. The waveguide directional head-up display system according to any one of claims 1-14, characterized in that, The head-up display system also includes at least one reflective element.

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