Head-up display device and single-ray machine multi-focal plane imaging method

Abstract

The invention discloses a head-up display device and a single-light-machine multi-focal-plane imaging method. The head-up display device comprises a projection light machine, a control module and a plurality of optical waveguide sheets, wherein the projection light machine is provided with a projection port; the optical waveguide sheet is arranged opposite to the projection port; the control module is connected with each optical waveguide sheet to control the optical waveguide sheet to be selectively in a grating state or a transparent state; wherein the divergence angles of coupled light rays of the plurality of optical waveguide sheets are different. Through the above mode, the projection light machine projects the image light to the optical waveguide sheet through the projection port, the image light enters the optical waveguide sheet, and then the image light is coupled out in a divergent light or parallel light state; wherein the divergence angles of the coupled light rays of the plurality of optical waveguide sheets are different, and the light rays with different divergence angles enter human eyes to form visual effects with different display distances, so that the image can be displayed at different visual distances under the condition that one projection light machine is adopted, a plurality of projection light machines are not required to be adopted, and the display efficiency is improved. The cost and the size of the device are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of head-up display, and in particular to a head-up display device and a single-light machine multi-focal plane imaging method. Background Art

[0002] The current mainstream head-up display solution is the W-shaped HUD (head-up display system). The W-HUD has the problem of short display distance. The driver cannot see the display image clearly when observing the road conditions in the distance. When the road conditions are good and farsightedness is required, it cannot meet the usage needs well. The AR-HUD system using the optical waveguide solution has parallel light as the output light. The display image perceived by the human eye is at infinity, which solves the problem of short display distance of the traditional W-HUD. However, in busy urban traffic conditions, the distance to the car is close, and the human eye sees the close-range image, and the waveguide-type HUD image will also become blurred. In order to solve the problem of imaging at both near and far distances, the W-shaped HUD can be equipped with dual optical machines or a single optical machine with dual optical paths to achieve dual-focal plane imaging, but imaging of more focal planes cannot be achieved. Of course, it can be forced to achieve it, but it requires many optical machines and multiple optical path structures, which is very expensive and has a huge size. Summary of the Invention

[0003] In order to solve the problems of difficulty, high cost and large size of multi-focal plane imaging in the prior art, the present invention provides a head-up display device and a single-light machine multi-focal plane imaging method.

[0004] The present application provides a head-up display device, comprising a projection optical engine, a control module, and a plurality of optical waveguide plates, wherein the projection optical engine has a projection port; the optical waveguide plates are arranged opposite to the projection port, and the optical waveguide plates can be transformed from a grating state to a transparent state; the control module is connected to the optical waveguide plates to control the optical waveguide plates to be selectively in a grating state or a transparent state; wherein the divergence angles of the coupled-out light of the plurality of optical waveguide plates are different.

[0005] In some embodiments, the optical waveguide sheet includes a substrate and a holographic material layer, the holographic material layer is provided with an in-coupling grating and an out-coupling grating, the holographic material layer is encapsulated inside the substrate, and the contact surface between the substrate and the holographic material layer is covered with a conductive film, the conductive film is connected to an electrode, and the electrode is used to connect to a control module to selectively energize or de-energize;

[0006] Wherein, when the conductive film is charged, the holographic material layer is in a grating state, and when the conductive film is not charged, the holographic material layer is in a transparent state.

[0007] In some embodiments, the propagation state of the outcoupled light of the outcoupling grating is a divergent light state or a parallel light state.

[0008] In some embodiments, the holographic material layer is further provided with a folded grating, and the folded grating is arranged in the light-emitting direction of the coupling-in grating and the light-incoming direction of the coupling-out grating.

[0009] In some embodiments, the holographic material layer uses a holographic polymer dispersed liquid crystal material.

[0010] In some embodiments, the control module of the head-up display device is connected to the plurality of electrodes, the plurality of electrodes are connected to the plurality of optical waveguide sheets in a one-to-one correspondence, and the electrodes are electrically connected to the conductive film;

[0011] Along the projection direction of the optical projection machine, a plurality of optical waveguide sheets are stacked layer by layer.

[0012] In some embodiments, the plurality of electrodes are energized alternately in a cycle, the projection light machine projects a plurality of images, the plurality of images are projected alternately in a cycle, and the plurality of images correspond one-to-one to the plurality of light waveguide sheets.

[0013] In some embodiments, the refresh rate of the projector for projecting a single image is greater than or equal to 60 Hz.

[0014] The present application also provides a single-light machine multi-focal plane imaging method, which uses the above-mentioned head-up display device and includes:

[0015] The optical projection machine can project multiple identical or different images, and the images correspond to the optical waveguide sheets one by one. When the optical waveguide sheet is not energized, the optical waveguide sheet is in a transparent state, and when the optical waveguide sheet is energized, the optical waveguide sheet is in a grating state. By energizing different optical waveguide sheets through the control module, the image light can be coupled out through different optical waveguide sheets, thereby displaying the image at different visual distances.

[0016] In some embodiments, the projection optical engine cyclically and alternately projects multiple identical or different images. At the same time, multiple optical waveguide plates are cyclically and alternately powered on. The cyclic alternation frequency of the images is the same as the frequency of the cyclic alternation of the optical waveguide plates. Each of the images is fixedly projected on the same optical waveguide plate. When the image is projected on the corresponding optical waveguide plate, the corresponding optical waveguide plate is energized to be in the grating state, and the other optical waveguide plates are in the transparent state. The light of multiple images is cyclically and alternately coupled out through the corresponding optical waveguide plates, so that the images can be displayed at multiple visual distances at the same time.

[0017] Compared with the prior art, a head-up display device according to an embodiment of the present invention has the following beneficial effects: a projection optical engine projects image light onto a light waveguide plate through a projection port and into the interior of the light waveguide plate, and then couples out light in the form of divergent light or parallel light; wherein, the divergence angles of the coupled light from the multiple light waveguide plates are different, and light with different divergence angles entering the human eye will form visual effects with different display distances. Thus, through the above-mentioned method, images can be displayed at different visual distances while using a single projection optical engine, without the need to use multiple projection optical engines, thereby reducing the cost and volume of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of an optical waveguide provided in one embodiment of the present application;

[0019] Figure 2 This is a schematic diagram of the first optical path principle of the head-up display device provided in one embodiment of the present application;

[0020] Figure 3 This is a schematic diagram of a second optical path principle of a head-up display device provided in one embodiment of the present application;

[0021] Figure 4 This is a schematic diagram of the third optical path principle of the head-up display device provided in one embodiment of the present application.

[0022] 100, optical waveguide; 11, holographic material layer; 111, in-coupling grating; 112, out-coupling grating; 12, conductive film; 13, substrate; 200, projection optical engine; 21, projection port. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below with reference to the accompanying drawings. The description in this part is only exemplary and explanatory and should not have any limiting effect on the scope of protection of the present invention.

[0024] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0025] It should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" and the like indicate positions or locations based on the positions shown in the accompanying drawings, or the positions or locations in which the inventive product is typically placed when in use. These terms are intended solely to facilitate and simplify the description of the present invention and are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third," etc., are used solely to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0026] Furthermore, terms such as "horizontal," "vertical," and "overhanging" do not necessarily imply that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0028] The present invention will be further described in detail below with reference to the accompanying drawings.

[0029] The present application provides a head-up display device, such as Figure 2 、 Figure 3 、 Figure 4 As shown, it includes a projection optical engine 200 , a control module and a plurality of optical waveguide sheets 100 .

[0030] like Figure 1 As shown, the optical waveguide plate 100 includes a substrate 13 and a holographic material layer 11. The holographic material layer 11 is provided with an in-coupling grating 111 and an out-coupling grating 112. The image light projected by the optical projection engine 200 enters the optical waveguide plate 100 through the in-coupling grating 111, then propagates inside the optical waveguide plate 100 by total internal reflection, is then coupled out through the out-coupling grating 112, and enters the human eye at a specific angle after being reflected by the windshield.

[0031] The holographic material layer 11 is encapsulated within a substrate 13, which can be made of high-transmittance glass or resin. The contact surface between the substrate 13 and the holographic material layer 11 is covered with a conductive film 12, which can be an indium tin oxide layer or a nanosilver wire layer. The conductive film 12 is connected to electrodes, which are used to connect to a control module to selectively charge or de-charge the holographic material layer 11. When the conductive film 12 is connected to the electrodes, the structure of the holographic material layer 11 changes under the action of the current. When the conductive film 12 is in a charged state, the holographic material layer 11 is in a grating state. When the conductive film 12 is in an uncharged state, the holographic material layer 11 is in a transparent state. When the holographic material layer 11 is in the grating state, the coupling-in grating 111 and the coupling-out grating 112 can diffract the incident light. When the holographic material layer 11 is in a transparent state, the holographic material layer 11 does not diffract the light, and the light can pass through the holographic material layer 11 normally.

[0032] The above-mentioned projection optical engine 200 has a projection port 21; the coupling-in grating 111 of the optical waveguide plate 100 is arranged opposite to the projection port 21. The projection optical engine 200 projects image light toward the coupling-in grating 111 of the optical waveguide plate 100 through the projection port 21. The image light enters the optical waveguide plate 100 through the internal total reflection and propagates, and is then coupled out through the coupling-out grating 112. The control module is connected to the electrodes of each optical waveguide plate 100 so that the electrodes can be selectively energized or de-energized. When the electrodes are energized, the optical waveguide plate 100 connected to the electrodes can be changed to a grating state. When the electrodes are de-energized, the optical waveguide plate 100 is in a transparent state. The outcoupled light from the multiple optical waveguide plates 100 has different divergence angles. Light with different divergence angles entering the human eye will produce visual effects with different display distances. Therefore, through the above-mentioned method, images can be displayed at different visual distances using a single projection optical engine 200, without using multiple projection optical engines 200, thereby reducing the cost and size of the device.

[0033] In order to further facilitate the understanding of the head-up display device provided by the present application, in other embodiments, the head-up display device provided by the present application includes an A light waveguide sheet 100, a B light waveguide sheet 100, and a C light waveguide sheet 100, wherein the outcoupling light of the A light waveguide sheet 100 is parallel light, and the outcoupling light of the B light waveguide sheet 100 and the C light waveguide sheet 100 are both divergent light, but the divergence angles of the outcoupling light of the B light waveguide sheet 100 and the C light waveguide sheet 100 are different. According to the visual characteristics of the human eye, when the image light is in the form of parallel light, the image light is directly received by the user. When the image light enters the human eye in a divergent state and is processed by the brain, the perceived image distance is infinite. Therefore, when the image light is projected onto the energized A optical waveguide sheet 100, the image seen by the human eye is displayed at infinity. When the image light enters the human eye at a divergent angle and is processed by the brain, the perceived image is displayed at a certain distance. The greater the divergence angle of the divergent light, the closer the perceived image display distance. Therefore, if the image light is coupled out through the B and C optical waveguide sheets 100, images can be displayed at different distances. As can be understood from the above description, by energizing different optical waveguide sheets 100, the image light can be controlled to be coupled out of different optical waveguide sheets 100, thereby enabling the image to be displayed at different distances.

[0034] like Figure 2 、 Figure 3 、 Figure 4 As shown, the head-up display device provided by the present application includes a plurality of the above-mentioned optical waveguide sheets 100. The conductive film 12 of each optical waveguide sheet 100 is controlled by a control module. The control module adjusts the structure of the holographic material layer 11 through the conductive film 12 to adjust the plurality of optical waveguide sheets 100 to be in a grating state or a transparent state. Since the divergence angles of the light coupled out of the multiple optical waveguide plates 100 are different, the image light projected by the projection optical machine 200 will form different display distances in the visual effect of the human eye after entering different optical waveguide plates 100 and being coupled out; specifically, when the image light passes through the optical waveguide plate 100 with a divergence angle of 0 degrees for the coupled-out light, the coupled-out light is parallel light. After the image light enters the human eye in the state of parallel light, the visual display distance is at infinity; when the image light passes through the optical waveguide plate 100 with a divergence angle of a certain angle for the coupled-out light, the image light will enter the human eye at a divergence angle. At this time, the image will form a display effect of a certain distance in the human eye. This certain distance is related to the divergence angle of the image light when it enters the human eye. The larger the divergence angle of the image light entering the human eye, the closer the display distance of the image formed in the human eye.

[0035] Based on the above principles, the head-up display device provided by the present application includes multiple optical waveguide sheets 100 with different divergence angles for outcoupling light. By controlling the image light to enter different optical waveguide sheets 100, different display distances can be visually achieved, thereby realizing image display through a single optical projection engine 200. In vehicle-mounted head-up display applications, drivers need to observe objects at different distances. Existing optical waveguide-type head-up display devices project image information light as parallel light, resulting in the displayed image appearing to be at infinity. When the driver is paying attention to nearby objects (such as following a vehicle), they cannot clearly observe the image information projected by the head-up display device. The head-up display device provided by the present application controls the diffraction outcoupling of image light at different optical waveguide sheets 100, allowing the image light projected by the optical projection engine 200 to enter the human eye not only in a parallel state but also at multiple divergence angles. This allows the image to be projected at different distances, thereby meeting the driver's observation needs at different viewing distances.

[0036] According to the above description, the propagation state of the outcoupled light of the outcoupling grating 112 of the above-mentioned optical waveguide plate 100 is a parallel light state or a divergent light state. The outcoupled light of the outcoupling grating 112 of different optical waveguide plates 100 includes only one propagation state. The multiple optical waveguide plates 100 include at least one optical waveguide plate 100 whose outcoupled light is parallel light. The light coupled out by the outcoupling grating 112 is parallel light, which is used to visually display an image at an infinite distance so that the human eye can observe it at a long distance. The light coupled out by the outcoupling grating 112 of other optical waveguide plates 100 is divergent light. The outcoupling grating 112 in which the outcoupling light is divergent light uses a beam of parallel light and a beam of divergent light to interfere with each other to expose the holographic material. If the outcoupling grating 112 of the optical waveguide plate 100 is manufactured using the above method, when the pattern light enters the optical waveguide plate 100 as parallel light and is totally reflected and propagated, it will be coupled out in the form of divergent light. After being projected into the human eye, a display effect with a certain distance will be formed in visual effect.

[0037] In some embodiments, the holographic material layer 11 of the optical waveguide sheet 100 provided herein is further provided with a folded grating. After entering the optical waveguide sheet 100 through the coupling-in grating 111, the image light is transmitted by total internal reflection to the folded grating. Part of the image light propagates forward at the folded grating, where it undergoes one-dimensional pupil expansion. After pupil expansion, the image light is redirected and transmitted by total internal reflection to the coupling-out grating 112, where it is coupled out. In practical applications, the pupil expansion effect of the folded grating allows for the use of a relatively compact projection optical engine 200, facilitating miniaturization of the head-up display device.

[0038] In some embodiments, the holographic material layer 11 of the optical waveguide sheet 100 provided in the present application may be made of a holographic polymer dispersed liquid crystal material, and the state change of the holographic material layer 11 may be controlled by applying electricity.

[0039] To facilitate controlling the light entering different light waveguide sheets 100, in some embodiments, the control module of the head-up display device provided herein is connected to multiple electrodes, each of which is connected one-to-one to each of the light waveguide sheets 100. The electrodes are also electrically connected to the conductive film 12. Along the projection direction of the optical projection engine 200, the multiple light waveguide sheets 100 are stacked, with air gaps between them. In actual applications, the control module controls each light waveguide sheet 100 to be in either a grating state or a transparent state via the electrodes. The image light projected by the optical projection engine 200 is directed perpendicularly toward the light waveguide sheet 100. Because the multiple light waveguide sheets 100 are stacked, the image light can pass through the transparent light waveguide sheet 100, then enter the grating light waveguide sheet 100 and couple out. The coupled-out light also passes through the transparent light waveguide sheet 100 and enters the human eye. This design eliminates the need to adjust the position of each light waveguide sheet 100 to control the image light entering the desired light waveguide sheet 100, facilitating the miniaturization of the head-up display device in practical applications.

[0040] In some embodiments, the plurality of electrodes are energized alternately in a cycle, and the optical projection machine 200 projects a plurality of images, which are projected alternately in a cycle, and the plurality of images correspond to the plurality of optical waveguide sheets 100 in a one-to-one manner. Figures 2 to 4As shown, the projection light engine 200 projects three images, and the display screens of the three images can be the same or different. The three images are projected alternately at a very fast speed. Accordingly, the control module controls the three optical waveguide sheets 100 through electrodes and energizes the three electrodes in a cycle. The cycle speed of the image projected by the projection light engine 200 matches the cycle speed of the electrode energization controlled by the control module, so that the three images projected by the projection light engine 200 are respectively and unchanged projected onto the three optical waveguide sheets 100 (that is, each optical waveguide sheet 100 always receives the same image); when the three images projected by the projection light engine 200 are the same, the same image information can be displayed on the visual effects at different distances, which can be used in the vehicle head-up display to facilitate the driver. The projected image information is understood at different viewing distances, and multi-focal plane projection of the image is achieved through a projector 200; when the three images projected by the projector 200 are different, it can be understood that when applied to an in-vehicle head-up display, different information can be displayed at different visual distances of the driver, enriching the display content of the in-vehicle head-up display; for example: when the road is empty and the driver is observing things in the distance, the projector 200 can project information such as the vehicle's speed and road speed limit at a long distance for the driver to understand in real time and avoid speeding; when there are many vehicles on the road and the speed is slow, when the driver is observing things at a close distance, the projector 200 can project the distance to the vehicle in front and the position information of surrounding vehicles to a close distance so that the driver can understand it in time. In summary, the head-up display device provided by the present application can project image information at multiple focal planes to facilitate observation by the human eye at different visual distances.

[0041] In some embodiments, the refresh rate of a single image projected by the head-up display device provided in the present application is greater than or equal to 60Hz. It is understood that the projector 200 utilizes the visual pause effect of the human eye when projecting an image. In order to ensure that the image projected by the projector 200 can be visually displayed continuously and stably, the refresh rate of a single image projected by the projector 200 must not be less than 60Hz (i.e., the number of times a single image is projected within one second must not be less than 60 times). If the projector 200 projects multiple images, the number of times each image is refreshed and projected within one second must not be less than 60 times to ensure a good display effect.

[0042] Specifically, if the head-up display device is provided with three optical waveguide sheets 100 , the corresponding head-up display device can project three images, which can be the same or different. If the refresh rate of each image is 60 Hz, the total refresh rate of the projector 200 is 180 Hz.

[0043] It should be noted that the limitation on the number of optical waveguide sheets 100 used above is only for the convenience of understanding and description, and this application does not impose any limitation on the number of optical waveguide sheets 100 used in the head-up display device provided in this application.

[0044] In other embodiments, the control module can control the electrodes to continuously energize any one of the optical waveguide sheets 100 so that the image light projected by the projection light engine 200 can be fixedly projected into any one of the optical waveguide sheets 100. Since the multiple optical waveguide sheets 100 have different projection distances in terms of visual effects, the above method can be used to fix the image at the required visual distance according to needs, thereby enriching the user experience.

[0045] The present application also provides a single-light machine multi-focal plane imaging method, which uses the above-mentioned head-up display device and includes:

[0046] The optical projection engine 200 can project multiple identical or different images, and the images correspond to the optical waveguide sheet 100 one-to-one. When the optical waveguide sheet 100 is not powered on, the optical waveguide sheet 100 is in a transparent state. When the optical waveguide sheet 100 is powered on, the optical waveguide sheet 100 is in a grating state. When the optical waveguide sheet 100 is in the transparent state, light passes through the optical waveguide sheet 100 directly without diffraction. When the optical waveguide sheet 100 is in the grating state, light passes through the optical waveguide sheet 100 and is diffracted into the interior of the optical waveguide sheet 100, and is coupled out from the coupling grating 112 for projection into the human eye. Due to the different structures of the coupling gratings 112 of the multiple optical waveguide sheets 100, the divergence angles of the coupled light are different, and the image display distance perceived by the human eye after entering the human eye is different. Therefore, when multi-focal plane projection of the image is required, the control module is used to power different optical waveguide sheets 100, so that the image light can be coupled out through different optical waveguide sheets 100, thereby displaying the image at different visual distances.

[0047] In some embodiments, the optical projection engine 200 cyclically and alternately projects multiple identical or different images. Simultaneously, multiple optical waveguide sheets 100 are cyclically and alternately powered. The cyclical alternation frequency of the images is the same as the cyclical alternation frequency of the optical waveguide sheets 100. Each image is fixedly projected onto the same optical waveguide sheet 100. When an image is projected onto a corresponding optical waveguide sheet 100, the corresponding optical waveguide sheet 100 is powered on to be in a grating state, while the other optical waveguide sheets 100 are in a transparent state.

[0048] Since the structures of the outcoupling gratings 112 of the multiple optical waveguide plates 100 are different, the divergence angles of the outcoupling light are different, and the display distances of the images perceived by the human eye after entering the human eye are different. Multiple images are projected alternately in a cycle and combined with the multiple optical waveguide plates 100 being energized alternately in a cycle, the visual pause effect of the human eye is utilized to simultaneously display images at different visual distances. That is, the simultaneous projection of multiple focal planes of the image is achieved through a single projection optical machine 200.

[0049] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0050] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0051] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A head-up display device, characterized in that: include: A projection optical machine (200) having a projection port (21); A plurality of optical waveguide sheets (100), wherein the optical waveguide sheets (100) are arranged opposite to the projection port (21), and the optical waveguide sheets (100) can be transformed from a grating state to a transparent state; A control module, the control module being connected to the optical waveguide sheet (100) to control the optical waveguide sheet (100) to be selectively in a grating state or a transparent state; Wherein, the divergence angles of the outcoupled light rays of the plurality of optical waveguide sheets (100) are different.

2. The head-up display device according to claim 1, characterized in that: The optical waveguide sheet (100) comprises a substrate (13) and a holographic material layer (11), the holographic material layer (11) is provided with an in-coupling grating (111) and an out-coupling grating (112), the holographic material layer (11) is packaged inside the substrate (13), the contact surface between the substrate (13) and the holographic material layer (11) is covered with a conductive film (12), the conductive film (12) is connected with an electrode, and the electrode is used to connect a control module to selectively charge or de-energize; Wherein, when the conductive film (12) is charged, the holographic material layer (11) is in a grating state, and when the conductive film (12) is not charged, the holographic material layer (11) is in a transparent state.

3. The head-up display device according to claim 2, characterized in that: The propagation state of the outcoupled light of the outcoupled grating (112) is a divergent light state or a parallel light state.

4. The head-up display device according to claim 2, characterized in that: The holographic material layer (11) is further provided with a folded grating, and the folded grating is arranged in the light-emitting direction of the coupling-in grating (111) and the light-incoming direction of the coupling-out grating (112).

5. The head-up display device according to claim 2, characterized in that: The holographic material layer (11) is made of holographic polymer dispersed liquid crystal material.

6. The head-up display device according to claim 2, characterized in that: The control module of the head-up display device is connected to a plurality of the electrodes, the plurality of the electrodes are connected to a plurality of the optical waveguide sheets (100) in a one-to-one correspondence, and the electrodes are electrically connected to the conductive film (12); Along the projection direction of the projection optical machine (200), a plurality of the optical waveguide sheets (100) are stacked layer by layer.

7. The head-up display device according to claim 6, characterized in that: The plurality of electrodes are energized alternately in a cycle, the projection optical machine (200) projects a plurality of images, the plurality of images are projected alternately in a cycle, and the plurality of images correspond one to one with the plurality of optical waveguide sheets (100).

8. The head-up display device according to claim 1, characterized in that: The refresh rate of a single image projected by the projection optical machine is greater than or equal to 60 Hz.

9. A single-light machine multi-focal plane imaging method, characterized in that: The single-light machine multi-focal plane imaging method adopts the head-up display device described in claim 1, and the single-light machine multi-focal plane imaging method includes: The projection optical machine (200) can project a plurality of identical or different images, wherein the images correspond to the optical waveguide sheets (100) one by one. When the optical waveguide sheet (100) is not powered, the optical waveguide sheet (100) is in a transparent state, and when the optical waveguide sheet (100) is powered, the optical waveguide sheet (100) is in a grating state. By powering on different optical waveguide sheets (100) through the control module, image light can be coupled out through different optical waveguide sheets (100), thereby displaying images at different visual distances.

10. The single-light machine multi-focal plane imaging method according to claim 9, characterized in that: The projection optical machine (200) projects a plurality of identical or different images in a cyclic and alternating manner. At the same time, a plurality of the optical waveguide sheets (100) are energized in a cyclic and alternating manner. The cyclic and alternating frequency of the images is the same as the frequency at which the optical waveguide sheets (100) are energized in a cyclic and alternating manner. Each of the images is fixedly projected on the same optical waveguide sheet (100). When the image is projected on the corresponding optical waveguide sheet (100), the corresponding optical waveguide sheet (100) is energized to be in the grating state, and the other optical waveguide sheets (100) are in the transparent state. The light rays of the plurality of images are coupled out in a cyclic and alternating manner through the corresponding optical waveguide sheets (100), so that the images can be displayed at multiple visual distances simultaneously.

Images