Head-up display device, head-up display method and vehicle

Abstract

The invention provides a head-up display device and a head-up display method. The head-up display device and the head-up display method can be applied to the fields of automobiles, aviation, spaceflight, navigation and the like. The head-up display device comprises a variable-focus holographic optical element HOE lens and an image projection device, the HOE lens is attached to the light-transmitting plane, the working time sequence of the HOE lens comprises N time periods, and the N time periods correspond to different focal lengths and different deflection angles respectively; the image projection device comprises an image generation module PGU and an optical lens group, the PGU is used for generating N projection images corresponding to N time periods, the optical lens group is used for projecting the N projection images to the HOE lens, and through reflection of the HOE lens, virtual images of the N projection images are focused to different depths outside the light-transmitting plane. According to the embodiment of the invention, double-screen and even multi-screen display can be realized based on one PGU and the variable-focus HOE lens, and the size and the cost of the image projection device in the HUD device are effectively reduced.

Description

[0001] This application is a divisional application of the original application with the application number 202080004894.5 and the original filing date of September 14, 2020, and the entire contents of the original application are incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the field of intelligent vehicles, and in particular, to a head-up display device, a head-up display method, and a vehicle. BACKGROUND

[0003] Head-up display (HUD) technology, also known as heads-up display technology, has been increasingly applied in the fields of automobiles, aerospace, and navigation in recent years. For example, in the field of automobiles, an image projection device in a HUD device projects important information during vehicle driving onto a windshield, and a virtual image is formed in front of the driver's line of sight through reflection of the windshield, so that the driver can see the information without lowering his head. Compared with the display mode of instrument panels and central control screens that require the driver to lower his head to observe, HUD avoids the driving risk caused by the driver's failure to pay attention to the road conditions when lowering his head to observe, and is a safer vehicle display mode.

[0004] Currently, traditional HUDs mainly display vehicle instrument information such as vehicle speed and fuel level, and the imaging distance is about 2 to 3 meters in order not to interfere with the road conditions. In recent years, augmented reality (AR) HUD (AR-HUD) has emerged, which superimposes digital images on the real environment outside the vehicle, so that the driver obtains an augmented reality visual effect, which can be used for AR navigation, adaptive cruise control, lane departure warning, etc. In order to better integrate AR images and road information, the imaging distance of AR-HUD is generally about 7 to 15 meters.

[0005] Since the imaging distances of AR-HUD and traditional HUD are not consistent, in order to display both vehicle speed and AR images, two focal plane images need to be generated. The mainstream solution is dual-screen display, which specifically realizes that two sets of picture generation units (PGUs) are used in the image projection device to generate AR images and instrument information, respectively, and then the virtual images of the AR images and the virtual images of the instrument information are projected to two focal planes outside the windshield to realize the display of traditional HUD and AR-HUD, as shown in FIG. 1. Figure 1 However, using two sets of PGUs to realize dual-screen display increases the volume and cost of the image projection device in the HUD device. SUMMARY

[0006] The present application provides a head-up display device, a head-up display method, and a vehicle, which can be used to reduce the volume and cost of the image projection device in the HUD device.

[0007] In a first aspect, a head-up display device is provided, comprising: a variable-focus holographic optical element (HOE) lens and an image projection device; the HOE lens is attached to a light-transmitting plane, and a working time sequence of the HOE lens comprises N time periods, and the HOE lens corresponds to different focal lengths and different deflection angles in the N time periods respectively, where N is a positive integer greater than or equal to 2; the image projection device comprises an image generation module (PGU) and an optical lens group, the PGU is configured to generate N projection images corresponding to the N time periods, and the optical lens group is configured to project the N projection images to the HOE lens, and the N projection images are focused to different depths outside the light-transmitting plane through reflection of the HOE lens.

[0008] It should be understood that the PGU generates N projection images corresponding to the N time periods, in other words, the PGU generates one image each time, and the N projection images corresponding to the N time periods are generated alternately.

[0009] The head-up display device of the embodiments of the present application comprises the HOE lens and the image projection device. The working time sequence of the HOE lens comprises N time periods, and the HOE lens corresponds to different focal lengths and different deflection angles in the N time periods respectively. The image projection device comprises a PGU, and the PGU is configured to generate N projection images corresponding to the N time periods. When the N projection images are projected to the HOE lens in the N time periods, the N projection images are focused and deflected to different degrees, so that virtual images corresponding to the N projection images can be presented at different depths outside the light-transmitting plane, and N screens (N≥2) are realized. That is, the present application can realize double-screen or even multi-screen display based on one PGU and the HOE lens, and the volume and cost of the image projection device in the HUD device are effectively reduced.

[0010] In combination with the first aspect, in some implementations of the first aspect, the HOE lens comprises M layers of HOE films, where M is a positive integer; the HOE films have at least two film states, including a transparent state and a diffraction state, and by respectively controlling the film states of each layer of the HOE films, the HOE lens corresponds to different focal lengths and different deflection angles in the N time periods respectively.

[0011] Optionally, a voltage can be loaded on each HOE film, and the film state of each layer of the HOE films is switched by controlling the opening and closing of the voltage.

[0012] In combination with the first aspect, in some implementations of the first aspect, if the film state of the HOE film is the transparent state, the HOE film does not have a focusing function and does not have a deflection angle; if the film state of the HOE film is the diffraction state, the HOE film has a focusing function and has a deflection angle.

[0013] It should be understood that if the film state of the HOE film is transparent state, the HOE film does not have focusing function and there is no deflection angle, which means that the focal length and the deflection angle of the HOE film are both 0 in the transparent state. If the film state of the HOE film is diffractive state, the HOE film has focusing function and there is deflection angle, which means that the focal length and the deflection angle of the HOE film are both not 0 in the diffractive state.

[0014] In combination with the first aspect, in some implementations of the first aspect, each of the M layers of HOE films has different focal length and different deflection angle when in the diffractive state, respectively.

[0015] In other words, each of the M layers of HOE films has different focusing ability and different deflection degree when in the diffractive state.

[0016] In combination with the first aspect, in some implementations of the first aspect, the deflection angle of the HOE film when in the diffractive state is 2° to 15°, and the deflection angle of the HOE lens is the sum of the deflection angles of all the HOE films in the diffractive state in the M layers of HOE films.

[0017] In combination with the first aspect, in some implementations of the first aspect, the relationship between M and N is N = 2M. M .

[0018] In combination with the first aspect, in some implementations of the first aspect, the HOE film is prepared by polymer dispersed liquid crystal (PDLC).

[0019] It should be understood that the polymer dispersed liquid crystal (PDLC) can present different states under the control of voltage. That is, the voltage is loaded on the HOE film, and the film state of the HOE film can be switched by controlling the opening and closing of the voltage.

[0020] In combination with the first aspect, in some implementations of the first aspect, the HOE film is prepared by any one of exposure method, electron beam lithography method or nanoimprint method.

[0021] In combination with the first aspect, in some implementations of the first aspect, the preparation method of the HOE lens is as follows: a parallel laser beam and a focused laser beam with deflection angle are used to interfere with each other on a polymer dispersed liquid crystal (PDLC) holographic plate to obtain the HOE film; and the M layers of the HOE film are stacked to obtain the HOE lens, wherein each of the M layers is prepared by using focused laser beams with different focal lengths and different deflection angles, respectively.

[0022] With reference to the first aspect, in some implementations of the first aspect, the apparatus further includes a controller configured to control the PGU to generate N projected images corresponding to the N time periods; and / or control the state of the HOE film of each layer such that the HOE lens corresponds to different focal lengths and different deflection angles at the N time periods, respectively.

[0023] With reference to the first aspect, in some implementations of the first aspect, the unit time includes K working periods, each working period includes N time periods, and K is greater than or equal to a preset threshold.

[0024] In the embodiments of the present application, by controlling the switching frequency of the N time periods, the human eye persistence effect can be utilized to simultaneously present N projected images at different depths outside the light transmission plane.

[0025] Optionally, the switching frequency of the N time periods can be controlled by the voltage frequency. That is, the frequency of the voltage on and off can be controlled.

[0026] With reference to the first aspect, in some implementations of the first aspect, the N projected images include a first projected image and a second projected image, the first projected image is configured to display instrument information, and the second projected image is configured to display augmented reality image information.

[0027] It should be understood that, in the embodiments of the present application, by controlling the focal length and deflection angle of the HOE lens corresponding to the time periods of the first projected image and the second projected image, different image contents can be displayed at different depths, that is, instrument information can be displayed at a distance of 2-3 meters, and augmented reality image information can be displayed at a distance of 7-15 meters, thereby realizing dual-screen display.

[0028] With reference to the first aspect, in some implementations of the first aspect, the optical mirror group includes a plane mirror and a curved mirror, the plane mirror and the curved mirror are located between the HOE lens and the PGU, and the N projected images are reflected to the HOE lens through the plane mirror and the curved mirror.

[0029] In a second aspect, a head-up display method is provided, which is implemented in a head-up display device, the head-up display device comprising: a variable-focus holographic optical element (HOE) lens and an image projection device; the HOE lens is attached to a light-transmitting plane, and a working time sequence of the HOE lens comprises N time periods, and the HOE lens corresponds to different focal lengths and different deflection angles in the N time periods respectively, where N is a positive integer greater than or equal to 2; the image projection device comprises an image generation module (PGU) and an optical lens group, the PGU is configured to generate N projection images corresponding to the N time periods; the head-up display method comprises: projecting the N projection images to the HOE lens through the optical lens group, and focusing virtual images of the N projection images to different depths outside the light-transmitting plane through reflection of the HOE lens.

[0030] With reference to the second aspect, in some implementations of the second aspect, the HOE lens comprises M layers of HOE films, where M is a positive integer; the HOE films have at least two film states, including a transparent state and a diffraction state, and by respectively controlling the film states of each layer of HOE films, the HOE lens corresponds to different focal lengths and different deflection angles in the N time periods respectively.

[0031] With reference to the second aspect, in some implementations of the second aspect, if the film state of the HOE film is the transparent state, the HOE film has no focusing function and no deflection angle; if the film state of the HOE film is the diffraction state, the HOE film has a focusing function and a deflection angle.

[0032] With reference to the second aspect, in some implementations of the second aspect, each layer of HOE films in the M layers of HOE films has different focal lengths and different deflection angles when in the diffraction state respectively.

[0033] With reference to the second aspect, in some implementations of the second aspect, the deflection angle of the HOE film in the diffraction state is 2° to 15°, and the deflection angle of the HOE lens is the sum of the deflection angles of all HOE films in the M layers of HOE films in the diffraction state.

[0034] With reference to the second aspect, in some implementations of the second aspect, the relationship between M and N is: N = 2 M .

[0035] With reference to the second aspect, in some implementations of the second aspect, the HOE film is prepared by any one of an exposure method, an electron beam lithography method, or a nano-imprint method.

[0036] With reference to the second aspect, in some implementations of the second aspect, the HOE lens is prepared by: obtaining the HOE film by interference of a parallel laser and a focused laser with a deflection angle on a polymer dispersed liquid crystal (PDLC) holographic plate; and stacking M layers of the HOE film to obtain the HOE lens, where each of the M layers is prepared by using a focused laser with a different focal length and a different deflection angle.

[0037] With reference to the second aspect, in some implementations of the second aspect, the time sequence includes K working periods in a unit of time, each of the working periods includes the N time periods, and K is greater than or equal to a preset threshold.

[0038] With reference to the second aspect, in some implementations of the second aspect, the N projected images include: a first projected image for displaying instrument information and a second projected image for displaying augmented reality image information.

[0039] With reference to the second aspect, in some implementations of the second aspect, the optical mirror group includes: a plane mirror and a curved mirror, the plane mirror and the curved mirror are located between the HOE lens and the PGU, and the N projected images are reflected to the HOE lens through the plane mirror and the curved mirror.

[0040] In a third aspect, a preparation method of a holographic optical element (HOE) lens is provided. The time sequence of the HOE lens includes N time periods, the HOE lens corresponds to different focal lengths and different deflection angles in the N time periods, where N is a positive integer greater than or equal to 2. The HOE lens includes M layers of HOE films, where M is a positive integer. The preparation method of the HOE lens is as follows: obtaining the HOE film by interference of a parallel laser and a focused laser with a deflection angle on a polymer dispersed liquid crystal (PDLC) holographic plate; and stacking M layers of the HOE film to obtain the HOE lens, where each of the M layers is prepared by using a focused laser with a different focal length and a different deflection angle.

[0041] With reference to the third aspect, in some implementations of the third aspect, the HOE film has at least two film states, the film states include a transparent state and a diffraction state, and by respectively controlling the film states of each of the HOE films, the HOE lens corresponds to different focal lengths and different deflection angles in the N time periods.

[0042] With reference to the third aspect, in some implementations of the third aspect, if the film state of the HOE film is the transparent state, the HOE film does not have a focusing function and does not have a deflection angle; and if the film state of the HOE film is the diffraction state, the HOE film has a focusing function and has a deflection angle.

[0043] In some implementations of the third aspect, the deflection angle of the HOE film in the diffractive state is 2° to 15°, and the deflection angle of the HOE lens is the sum of the deflection angles of all the HOE films in the diffractive state in the M layers of HOE films.

[0044] In some implementations of the third aspect, the relationship between M and N is N = 2M. M .

[0045] In a fourth aspect, a vehicle is provided, which includes the apparatus as in the first aspect or any possible implementation of the first aspect.

[0046] In a fifth aspect, a vehicle-mounted system is provided, which includes the apparatus as in the first aspect or any possible implementation of the first aspect.

[0047] In a sixth aspect, a control method of an HOE lens is provided, the HOE lens including M layers of HOE films, M being a positive integer, the HOE films having at least two film states including a transparent state and a diffractive state, the method including: by respectively controlling the film states of each layer of HOE films, making the HOE lens correspond to different focal lengths and different deflection angles in the N time periods respectively.

[0048] In a seventh aspect, a controller is provided, which includes an input-output interface, a processor and a memory, the processor being configured to control the input-output interface to transceive signals or information, the memory being configured to store a computer program, and the processor being configured to call and run the computer program from the memory, so that the controller executes the method in any of the aspects.

[0049] In an eighth aspect, a computer program product including instructions is provided, which, when executed on a computer, causes the computer to execute the method in the second aspect or any implementation of the second aspect, and / or execute the method in the third aspect or any implementation of the third aspect, and / or execute the method in the sixth aspect or any implementation of the sixth aspect.

[0050] In a ninth aspect, a computer-readable storage medium is provided, which stores program code for execution by an apparatus, the program code including instructions for executing the method in the second aspect or any possible implementation of the second aspect, and / or instructions for executing the method in the third aspect or any implementation of the third aspect, and / or instructions for executing the method in the sixth aspect or any implementation of the sixth aspect.

[0051] In a tenth aspect, a chip is provided, which includes a processor and a data interface, the processor reads instructions stored on a memory through the data interface, executes the method in the second aspect or any possible implementation manner of the second aspect, and / or executes the method in the third aspect or any implementation manner of the third aspect, and / or executes the method in the sixth aspect or any implementation manner of the sixth aspect.

[0052] Optionally, as an implementation manner, the chip can further include a memory, the memory stores instructions, and the processor is configured to execute the instructions stored on the memory, and when the instructions are executed, the processor is configured to execute the method in the second aspect or any possible implementation manner of the second aspect, and / or execute the method in the third aspect or any implementation manner of the third aspect, and / or execute the method in the sixth aspect or any implementation manner of the sixth aspect. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 FIG. 1 is an example diagram of a head-up display scene provided by an embodiment of the present application;

[0054] Figure 2 FIG. 2 is a planar example diagram of a head-up display scene provided by an embodiment of the present application;

[0055] Figure 3 FIG. 3 is an example diagram of an existing head-up display device provided by an embodiment of the present application;

[0056] Figure 4 FIG. 4 is an example diagram of an application scene of a head-up display provided by an embodiment of the present application;

[0057] Figure 5 FIG. 5 is an example diagram of a head-up display device provided by an embodiment of the present application;

[0058] Figure 6 FIG. 6 is an example diagram of a PDLC material state switching provided by an embodiment of the present application;

[0059] Figure 7 FIG. 7 is a structural example diagram of a double-screen head-up display device provided by an embodiment of the present application;

[0060] Figure 8 FIG. 8 is a structural example diagram of another double-screen head-up display device provided by an embodiment of the present application;

[0061] Figure 9 FIG. 9 is a structural example diagram of a four-screen head-up display device provided by an embodiment of the present application;

[0062] Figure 10 FIG. 10 is an example diagram of a preparation method of a HOE lens provided by an embodiment of the present application;

[0063] Figure 11 is an example diagram of a variable focal HOE film prepared by an exposure method according to an embodiment of the present application;

[0064] Figure 12 is an example diagram of a head-up display method according to an embodiment of the present application. DETAILED DESCRIPTION

[0065] The technical solutions in the present application will be described below with reference to the accompanying drawings.

[0066] The head-up display (HUD) technology, also known as the view display technology, has been increasingly applied in the automotive field, the aerospace field, and the marine field in recent years. For example, it can be applied to vehicles, and can also be applied to airplanes, aerospace vehicles, ships, and other transportation tools. For ease of description, the vehicle-mounted HUD is taken as an example for description in the present application. However, it should be understood that this does not limit the present application.

[0067] The current traditional vehicle-mounted HUD mainly displays vehicle instrument information such as vehicle speed and fuel quantity. In order not to interfere with the road conditions, the imaging distance is about 2 to 3 meters. The augmented reality (AR) HUD (AR-HUD) that has emerged in recent years superimposes a digital image on the real environment outside the vehicle, so that the driver obtains the visual effect of augmented reality, which can be used in scenarios such as AR navigation, adaptive cruise, and lane departure warning. In order to better integrate the AR image and the road information, the imaging distance of the AR-HUD is generally about 7 to 15 meters. As can be seen, the imaging distance of the AR-HUD is not consistent with that of the traditional HUD. In order to display both the vehicle instrument information such as vehicle speed and the AR image, two focal plane images need to be generated. In order to improve the experience of the driver and the safety of driving, it is usually required that the two focal plane (double screen) images do not overlap and interfere with each other. It should be understood that the "screen" involved in the present application is the imaging position of a virtual image, rather than a screen in the actual sense.

[0068] Figure 2 is a planar example diagram of a head-up display scene according to an embodiment of the present application. As shown in Figure 2 The image projection device in the vehicle-mounted HUD device can be installed near the windshield. The image projection device can use the windshield or the light-transmitting plane such as the glass near the windshield or the mirror to image the projected object A and object B at different depths outside the windshield, so that the driver can see these driving information without lowering his head or turning his head. The object A can display vehicle instrument information such as vehicle speed and fuel quantity. The object B can display AR image information, which superimposes a digital image on the real environment outside the vehicle.

[0069] The prior art uses two sets of picture generation units (PGUs) in the image projection device to simultaneously realize traditional HUD and AR-HUD on two focal planes respectively. As shown in Figure 3 The two sets of PGUs share the rear curved mirror optical system. Due to the different distances from the curved mirror, the virtual image positions formed through the windshield are different, forming two images displayed at different depths of A screen and B screen. The closer A screen can display instrument information, and the farther B screen can display AR image information.

[0070] However, using two sets of PGUs to realize double-screen display increases the volume and cost of the image projection device in the HUD device.

[0071] To solve the above problems, the application provides a head-up display device, which mainly realizes double-screen or even multi-screen display based on one PGU and a variable-focus holographic optical element (HOE) lens, effectively reducing the cost and volume of the image projection device.

[0072] The variable-focus HOE lens is composed of a polymer film, can be used as a diffractive optical element, and can be attached to the windshield. The HOE lens can reflect the image light generated by the PGU in the image projection device, and by controlling the focal length of the HOE lens, the virtual image of the image can be focused at different depths outside the vehicle. Thus, the use of two sets of PGUs in the image projection device is effectively avoided, and the distance of the two sets of PGUs from the curved mirror is controlled to realize imaging at different depths, thereby effectively reducing the cost and volume of the image projection device.

[0073] In order to better understand the scheme of the embodiments of the application, before describing the device of the embodiments of the application, first of all, the accompanying drawings are combined Figure 4 An application scenario of the embodiments of the application is briefly described.

[0074] Figure 4 is an application scenario example of the head-up display provided by the embodiments of the application.

[0075] As shown in Figure 4 The application scenario provided by the application is a vehicle-mounted HUD. When the driver drives the car, the image projection device (usually placed in the console below the windshield of the car) in the vehicle projects an image, which is reflected by the HOE lens attached to the windshield, so that the virtual image corresponding to the image area is focused at different depths outside the vehicle. The closer virtual image screen can display instrument information, and the imaging distance is about 2 to 3 meters. The farther virtual image screen displays AR navigation, AR warning, etc. information, and the imaging distance is about 7 to 15 meters.

[0076] The head-up display device provided by the present application will be described in detail below with reference to the accompanying drawings. Figure 5 is an example diagram of a head-up display device provided by an embodiment of the present application. As shown in the diagram, the head-up display device 400 includes a HOE lens 410 and an image projection device 420. Figure 5

[0077] The HOE lens 410 is attached to a light-transmitting plane, and the working time sequence of the HOE lens 410 includes N time periods, and the HOE lens 410 corresponds to different focal lengths and different deflection angles in the N time periods respectively, where N is a positive integer greater than or equal to 2.

[0078] The image projection device 420 includes an image generation module PGU 421 and an optical lens group 422. The PGU 421 is configured to generate N projection images corresponding to the N time periods, and the optical lens group 422 is configured to project the N projection images to the HOE lens 410, and the virtual images of the N projection images are focused at different depths outside the light-transmitting plane through reflection of the HOE lens 410.

[0079] It should be understood that the HOE lens 410 of the present application is a variable-focus lens, and its focal length and deflection angle change with the time period. Meanwhile, the PGU alternately generates different projection images corresponding to different time periods. That is, any one image generated by the PGU corresponds to a focal length and a deflection angle, thereby realizing the presentation of different images at different depths and different positions outside the vehicle.

[0080] It should be understood that in actual application, if only the virtual images are required not to coincide but the imaging depth is not required, then it is also possible to only require the HOE lens 410 to correspond to different deflection angles in the N time periods. The specific operation mode should be determined according to the actual situation, and the present application does not limit this.

[0081] It should be understood that the present application does not limit the length of each time period in the N time periods, which means that the lengths of the N time periods can be the same or different, which means that the time length of each image displayed when the PGU alternately generates the N projection images can be different. It should be understood that in the specific implementation mode below, the same N time periods are taken as an example for ease of description.

[0082] It should be understood that different deflection angles can refer to different sizes of deflection angles, and can also refer to deflection angles of different sizes and different deflection directions. Thus, by controlling the focal length size, deflection angle size, and deflection direction of the HOE lens at each time period in the N time periods, the virtual images of the N projection images can be arranged in an up-down manner, or in a left-right manner, or in other manners at different depths outside the light-transmitting plane. Meanwhile, it is also possible to ensure that the virtual images corresponding to the N projection images do not overlap with each other and do not interfere with each other.

[0083] ​The head-up display device provided in the embodiments of the present application comprises a HOE lens and an image projection device. The working time sequence of the HOE lens comprises N time periods, and the HOE lens corresponds to different focal lengths and different deflection angles in the N time periods respectively. The image projection device comprises a PGU, which is used to generate N projection images corresponding to the N time periods. When the N projection images are projected to the HOE lens in the N time periods respectively, the N projection images are focused and deflected to different degrees, so that the virtual images corresponding to the N projection images can be presented at different depths outside the light transmission plane, and N-screen (N≥2) display is realized. That is, the double-screen or even multi-screen display can be realized based on the PGU and the HOE lens, and the volume and cost of the image projection device in the HUD device are effectively reduced.

[0084] Optionally, K working cycles are included in the unit time, each working cycle comprises N time periods, and K is greater than or equal to a preset threshold.

[0085] In the embodiments of the present application, the switching frequency of the N time periods is controlled, so that the virtual images of the N projection images can be presented at different depths outside the light transmission plane simultaneously by using the persistence of vision of the human eye. For example, if N=2, the switching frequency of the 2 time periods and the 2 projection images can be controlled to be 24 Hz, or 36 Hz, 48 Hz or 72 Hz, etc. Generally, when the switching frequency of the image is greater than or equal to 24 Hz, the continuous image can be seen due to the persistence of vision of the human eye, so that the virtual images of the 2 projection images can be presented at different depths outside the light transmission plane simultaneously. It should be understood that, in actual application, the switching frequency can be set according to actual needs, which is not limited in the present application.

[0086] Optionally, the HOE lens comprises M HOE films, M is a positive integer; the HOE film has at least two film states, the film states comprise a transparent state and a diffraction state, and the HOE lens corresponds to different focal lengths and different deflection angles in the N time periods by respectively controlling the film states of each HOE film.

[0087] It should be understood that, if the film state of the HOE film is the transparent state, the HOE film does not have focusing function and does not have deflection angle; if the film state of the HOE film is the diffraction state, the HOE film has focusing function and has deflection angle. In other words, if the film state of the HOE film is the transparent state, the focal length and the deflection angle of the HOE film are both 0. If the film state of the HOE film is the diffraction state, the focal length and the deflection angle of the HOE film are both not 0. That is, by controlling the film state of each HOE film, the HOE lens can have different deflection ability and focusing ability.

[0088] Optionally, the deflection angle of the HOE film in the diffraction state can be in the range of 2° to 15°.

[0089] Optionally, the deflection angle of the HOE lens is the sum of the deflection angles of all HOE films in the M-layer HOE film in the diffractive state.

[0090] Optionally, each of the M-layer HOE films can have different focal lengths and different deflection angles when in the diffractive state. In other words, each of the M-layer HOE films has different focusing ability and deflection degree when in the diffractive state.

[0091] At this time, the relationship between M and N can be N = 2 M For example, if the HOE lens includes one layer of HOE film, two working states can be achieved, one is transparent state, and the other is diffractive state, and the two working states can be performed in two time periods; for example, if the HOE lens includes two layers of HOE film, each layer of film has two film states, and the focal lengths and deflection angles of the two layers of film in the diffractive state are different, four working states can be achieved according to permutation and combination, and the four working states can be performed in four time periods. More layers can also use the above-mentioned manner, which will not be described here.

[0092] Optionally, each of the M-layer HOE films can also have the same focal length and deflection angle when in the diffractive state. At this time, N and M no longer satisfy the above relationship. For example, if the HOE lens includes two layers of HOE film, each layer of film has two film states, and the focal lengths and deflection angles of the two layers of film in the diffractive state are the same, then there are three working states: one is to control both layers to be in the transparent state; one is to control any one layer to be in the transparent state and the other layer to be in the diffractive state; and the other is to control both layers to be in the diffractive state, and the three working states can be performed in three time periods, respectively presenting different images at three depths.

[0093] Optionally, each of the M-layer HOE films can also have different focal lengths and deflection angles when in the diffractive state. The present application does not limit this, and for ease of description, it is considered below that each of the M-layer HOE films has different focal lengths and different deflection angles when in the diffractive state. In the specific embodiments below, one layer and two layers will be described as examples.

[0094] Optionally, the head-up display 400 can further comprise a controller. The controller can be configured to control the PGU to generate N projection images corresponding to the N time periods, and / or to control the film state of each HOE film such that the HOE lens corresponds to different focal lengths and different deflection angles in the N time periods, respectively. Optionally, the HOE film can be made of polymer dispersed liquid crystal (PDLC) or other material with switchable refractive index. In the embodiments of the present application, PDLC is used to make the HOE film, but this should not be considered as a limitation of the present application.

[0095] It should be understood that the PDLC material can present different states under the control of voltage. This means that a voltage can be loaded on each HOE film to switch the film state of each HOE film by controlling the opening and closing of the voltage. Further, the control of the switching frequency of the N time periods can be achieved by controlling the frequency of the voltage. Optionally, the PDLC material can be a positive PDLC material or a negative PDLC material.

[0096] For example, Figure 6 is an example diagram of the state switching of a PDLC material. The PDLC material is a positive PDLC material, which has two states: when the voltage is off, it is in a diffraction state, has a focusing function of a lens, and the chief ray has a certain deflection angle, as shown in (a) of Figure 6 ; when the voltage is on, it is in a transparent state, the focusing function and the deflection angle disappear, as shown in (b) of Figure 6 . For example, the HOE film can also be made of a negative PDLC material. At this time, when the voltage is on, it is in a diffraction state, has a focusing function of a lens, and the chief ray has a certain deflection angle; when the voltage is off, it is in a transparent state, the focusing function and the deflection angle disappear. For ease of description, the HOE film in the embodiments of the present application is made of a positive PDLC material.

[0097] Optionally, the HOE film can be made by any one of the exposure method, the electron beam lithography method or the nano-imprint method.

[0098] Optionally, the method for making the HOE film can be as follows: a parallel laser beam and a focused laser beam with a deflection angle are used to interfere with each other on a polymer dispersed liquid crystal (PDLC) holographic plate to obtain the HOE film. The specific preparation method will be described in detail below, and will not be described here again.

[0099] The method for making the HOE lens 410 is as follows: M layers of the above-mentioned HOE film are stacked to obtain the HOE lens. Optionally, each layer of the M layers is made by using a focused laser beam with different focal lengths and different deflection angles.

[0100] It should be understood that in the automobile, the light-transmitting plane can be a windshield or a glass near the windshield, a mirror, or the like. Since the vehicle-mounted HUD is taken as an example in the following embodiments, the light-transmitting plane is described as a windshield for ease of description in the embodiments of the present application.

[0101] Optionally, the image projection device 420 can also be referred to as a HUD light machine, which is configured to project light rays of the image generated by the PGU 421 into different regions of the HOE lens 410. The image projection device 420 can be placed in a console below the windshield, or can be placed at other positions near the windshield, as long as the image light rays projected thereby can be reflected by different regions of the HOE lens 410 to present corresponding virtual images at different depths outside the windshield, which is not limited in the present application.

[0102] Optionally, the N projected images include a first projected image and a second projected image. The first projected image is configured to display instrument information, and the second projected image is configured to display augmented reality image information.

[0103] It should be understood that in the embodiments of the present application, by controlling the focal length and deflection angle of the HOE lens in the time period corresponding to the first projected image and the second projected image, different image contents can be displayed at different depths, that is, instrument information can be displayed at a distance of 2 to 3 meters, and augmented reality image information can be displayed at a distance of 7 to 15 meters, so as to realize double-screen display.

[0104] Optionally, the optical mirror group 422 can include two curved mirrors; or can include one curved mirror and one plane mirror; or can include one curved mirror and one or more lenses; or can include one plane mirror and a lens, which is not limited in the present application.

[0105] Exemplarily, the optical mirror group 422 includes a plane mirror M1 and a curved mirror M2, and the plane mirror M1 and the curved mirror M2 are located between the HOE lens 410 and the PGU 421. The N projected images are reflected to the HOE lens 410 through the plane mirror M1 and the curved mirror M2.

[0106] It should be understood that the HOE lens 410 can be attached to the outside of the windshield, or can be attached to the inside of the windshield, or can be used as a cladding layer of the windshield, which is not limited in the present application.

[0107] Preferably, in the embodiment of the present application, the HOE lens 410 is attached to the inner side of the windshield. This is because the reflectivity is about 10% when reflecting through the existing windshield; while the HOE lens 410 is attached to the inner side of the windshield, the HUD image is reflected through the HOE lens 410, and the reflection efficiency is more than 50%, thereby being able to improve the image brightness, while also being able to reduce the power consumption.

[0108] In the embodiment of the present application, the depth and imaging position of the virtual image are realized by controlling the focal length and deflection angle of the HOE lens, rather than by controlling the distance of different image regions to the curved mirror, thereby not needing special HUD rear-end optical lens group design, and reducing the optical design and processing difficulty.

[0109] In the embodiment of the present application, since the HOE lens has a lens function when at least one layer of film in the HOE lens is in a diffraction state, the image from the HUD can be magnified, and thus the field of view of the system can be further improved. In addition, the existing HUD uses the windshield to reflect the HUD image, and since the two surfaces inside and outside the glass reflect the image and have a certain deviation, ghosting will occur. However, when at least one layer of film in the HOE lens used in the present application is in a diffraction state, the reflection of the image region belongs to the diffraction principle, and usually only one diffraction occurs, and the diffraction angle is different from the reflection angle of the windshield. Therefore, the user will only observe one diffraction image of the HUD, and will not observe the reflected images inside and outside the windshield, and will not observe ghosting.

[0110] Exemplarily, the following will be described in combination with Figures 7 to 9 The specific structure of the head-up display device in the embodiment of the present application will be described in detail.

[0111] Figure 7 is a structure example diagram of a double-screen head-up display device provided by the embodiment of the present application.

[0112] As shown in Figure 7 , the head-up display device mainly comprises an image projection device, a windshield, and a HOE lens. The HOE lens comprises a layer of HOE film attached to the inner side of the windshield, and the HOE film is loaded with a square wave voltage. The image projection device comprises a PGU, a plane mirror M1, and a curved mirror M2. The PGU constantly alternately generates two images according to the switching frequency of the film state, and the time interval of the switching of the two images is half the period of the square wave voltage.

[0113] Specifically, when the voltage is 0, i.e., the voltage is off, the HOE lens is in a diffraction state, at this time the focal length of the HOE lens is f0, and the deflection angle is Δθ, which together with other lenses in the HUD light machine causes one image generated by the PGU to be imaged at the B screen, as shown in Figure 8as shown in (a) of FIG. 1. When the voltage is not 0, i.e. the voltage is on, the focal length and the deflection angle are 0, and the PGU generates another image under the action of other lenses in the HUD light machine, which is imaged at the A screen, as shown in (b) of FIG. 1. Figure 8 By controlling the frequency of the square wave voltage, for example, controlling the voltage frequency to be greater than 24 Hz, the driver can simultaneously observe the virtual images at the A screen and the B screen by using the persistence of vision of the human eye.

[0114] It should also be understood that the above embodiment is only an example, and in actual operation, the imaging position can be controlled by controlling the direction and size of the deflection angle, or the nearness and remoteness of the imaging can be controlled by controlling the size or sign of the focal length, which is not limited in the present application.

[0115] In the present embodiment, only one PGU is used to realize double-screen display. Moreover, by controlling the switching frequency of the film state, the focal length and the deflection angle, the driver can simultaneously observe the closer A screen and the farther B screen, and the images of the A screen and the B screen do not overlap and interfere with each other.

[0116] Figure 9 is a structural example of a four-screen head-up display device provided by the present embodiment. As shown in Figure 9 , the head-up display device mainly comprises an image projection device, a windshield and a HOE lens. The HOE lens comprises two layers of HOE films attached to the inner side of the windshield, and the two layers of HOE films are loaded with voltages, respectively. The deflection angles of the two layers of HOE films when in the diffraction state are θ1 and θ2, respectively. The image projection device comprises a PGU, a plane mirror M1 and a curved mirror M2. In actual operation, the film state of each layer of HOE film is switched by opening and closing the voltage, so that the HOE lens presents four different focal lengths and deflection angles in four time periods, respectively, and the PGU correspondingly generates four images in the four time periods. In the present embodiment, taking four time periods as one cycle, the number of cycles per unit time or the switching frequency of the four time periods, i.e. the voltage frequency, can be controlled, so that the driver can simultaneously observe the virtual images at the A screen, the B screen, the C screen and the D screen by using the persistence of vision of the human eye.

[0117] Exemplarily, as shown in Figure 9 , the four time periods are divided into four time periods t1, t2, t3 and t4, and the voltage of the HOE 1 and the HOE 2 is switched in the four time periods, respectively.

[0118] Time period t1: The voltages of the HOE 1 and the HOE 2 are both on. At this time, the HOE 1 and the HOE 2 are both in the transparent state, and the focal length and the deflection angle are both 0, so that the virtual image of the image 1 corresponding to the time period 1 is at the A screen with a depth 1.

[0119] At time t2: HOE 1 voltage is off, HOE 2 voltage is on. At this time, HOE 2 is in a transparent state with a focal length and deflection angle of 0; HOE 1 is in a diffraction state with a focal length of not 0 and a deflection angle of θ1. Therefore, the virtual image of image 2 corresponding to time 2 is deflected by θ1 and is located on screen B at depth 2.

[0120] At time t3: HOE 1 voltage is on, HOE 2 voltage is off. At this time, HOE 1 is in a transparent state with a focal length and deflection angle of 0; HOE 2 is in a diffraction state with a focal length of not 0 and a deflection angle of θ2. Therefore, the virtual image of image 3 corresponding to time 3 is deflected by θ2 and is located on screen C at depth 3.

[0121] At time t4: the voltages of HOE 1 and HOE 2 are both off. At this time, both HOE 1 and HOE 2 are in a diffraction state, and their focal lengths are not 0. The deflection angle of HOE 1 is θ1, and the deflection angle of HOE 2 is θ2. Therefore, the virtual image of image 4 corresponding to time 4 is deflected by θ1+θ2 and is located on screen D at depth 4.

[0122] In this embodiment, four-screen display can be achieved using only one PGU.

[0123] It should also be understood that the above embodiments are merely examples. In actual operation, the imaging position can be controlled by controlling the direction and magnitude of the deflection angle; or the distance of the image can be controlled by controlling the magnitude or sign of the focal length. This application does not limit this.

[0124] Furthermore, 3 layers of HOE film can be used to achieve 8-screen display, or 5 layers of HOE film to achieve 16-screen display, ..., or M layers of HOE film to achieve 2 M Screen display.

[0125] It should be understood that HUD displays with three or more screens can also be achieved by controlling the switching method of the voltage or controlling the focal length and deflection angle when the thin film is in the diffraction state, providing richer stereoscopic image displays for AR navigation.

[0126] Figure 10 This is an example diagram illustrating a method for fabricating a HOE lens according to an embodiment of this application. The working sequence of the HOE lens includes N time periods, each corresponding to a different focal length and a different deflection angle, where N is a positive integer greater than or equal to 2. The HOE lens comprises M layers of variable-focus HOE thin films, where M is a positive integer.

[0127] like Figure 10 As shown, the HOE lens fabrication method 900 includes steps S910 and S920. These steps are described in detail below.

[0128] S910, interference of a parallel laser beam and a focused laser beam with a deflection angle on a polymer dispersed liquid crystal (PDLC) holographic plate to obtain a HOE film. Specifically, as shown in Figure 11

[0129] It should be understood that the two laser beams can be emitted by the same laser, and obtained by a light splitting device.

[0130] Optionally, the deflection angle of the focused laser needs to be defined according to the specifications of the HUD used in actual operation. The common deflection angle can be 2° to 15°.

[0131] Optionally, in addition to the exposure method, the method for making the HOE film also includes electron beam lithography, nanoimprint, etc., which are not limited by the present application.

[0132] It should be understood that the HOE film has at least two film states, including a transparent state and a diffraction state, and by respectively controlling the film state of each layer of the HOE film, the HOE lens corresponds to different focal lengths and different deflection angles in N time periods.

[0133] It should be understood that if the film state of the HOE film is the transparent state, the HOE film does not have a focusing function and there is no deflection angle; if the film state of the HOE film is the diffraction state, the HOE film has a focusing function and there is a deflection angle.

[0134] S920, stacking M layers of HOE films to obtain a HOE lens.

[0135] Optionally, each layer in the M layers can be prepared by using focused laser beams with different focal lengths and different deflection angles.

[0136] Optionally, the deflection angle of the HOE lens can be the sum of the deflection angles of all HOE films in the M layers of HOE films in the diffraction state.

[0137] Optionally, the relationship between M and N can be: N = 2 M .

[0138] Figure 12 is an example of a head-up display method provided by the present application. As shown in Figure 12 The head-up display method 1100 is implemented in a head-up display device 400, which includes a variable-focus holographic optical element (HOE) lens and an image projection device; the HOE lens is attached to a light-transmitting plane, and the working time sequence of the HOE lens includes N time periods, and the HOE lens corresponds to different focal lengths and different deflection angles in N time periods, wherein N is a positive integer greater than or equal to 2; the image projection device includes an image generation module (PGU) and an optical lens group, and the PGU is used to generate N projection images corresponding to the N time periods. ​

[0139] The head-up display method 1100 comprises a step S1110 of projecting N projected images to the HOE lens through the optical lens group, and focusing the virtual images of the N projected images to different depths outside the light transmission plane through reflection of the HOE lens.

[0140] Optionally, the HOE lens comprises M layers of HOE films, M being a positive integer; the HOE films have at least two film states, the film states comprising a transparent state and a diffraction state, and by respectively controlling the film states of each layer of HOE films, the HOE lens corresponds to different focal lengths and different deflection angles in N time periods respectively.

[0141] Optionally, if the film state of the HOE film is the transparent state, the HOE film has no focusing function and no deflection angle; if the film state of the HOE film is the diffraction state, the HOE film has a focusing function and a deflection angle.

[0142] Optionally, each layer of HOE film in the M layers of HOE films has a different focal length and a different deflection angle when in the diffraction state.

[0143] Optionally, the deflection angle of the HOE film in the diffraction state is 2° to 15°, and the deflection angle of the HOE lens is the sum of the deflection angles of all the HOE films in the M layers of HOE films in the diffraction state.

[0144] Optionally, the relationship between M and N is: N = 2 M .

[0145] Optionally, the HOE film is prepared by any one of an exposure method, an electron beam lithography method or a nano-imprinting method.

[0146] Optionally, the preparation method of the HOE lens is as follows: a parallel laser beam and a focused laser beam with a deflection angle are used to interfere with each other on a polymer dispersed liquid crystal (PDLC) holographic plate to obtain the HOE film; and the M layers of HOE films are laminated to obtain the HOE lens, wherein each layer in the M layers is prepared by using a focused laser beam with a different focal length and a different deflection angle.

[0147] Optionally, a unit of time comprises K working cycles, each working cycle comprises N time periods, and K is greater than or equal to a preset threshold.

[0148] Optionally, the N projected images comprise a first projected image and a second projected image, the first projected image is used to display instrument information, and the second projected image is used to display augmented reality image information.

[0149] Optionally, the optical lens group comprises a plane mirror and a curved mirror, the plane mirror and the curved mirror are located between the HOE lens and the PGU, and the N projected images are reflected to the HOE lens through the plane mirror and the curved mirror.

[0150] The embodiment of the present application also provides a vehicle comprising the head-up display device 400.

[0151] The embodiment of the present application also provides a vehicle-mounted system comprising the head-up display device 400.

[0152] The embodiment of the present application also provides a control method of a HOE lens, the HOE lens comprising M layers of HOE films, M being a positive integer; the HOE films having at least two film states, the film states comprising a transparent state and a diffraction state, the method comprising: by respectively controlling the film states of each layer of HOE films, making the HOE lens correspond to different focal lengths and different deflection angles in the N time periods respectively.

[0153] The embodiment of the present application also provides a controller, comprising an input-output interface, a processor and a memory, the processor being configured to control the input-output interface to transceive signals or information, the memory being configured to store a computer program, and the processor being configured to call and run the computer program from the memory, so that the controller executes the method 900, and / or executes the method 1100, and / or executes the control method of the HOE lens. The embodiment of the present application also provides a computer program product comprising instructions, when the computer program product is run on a computer, so that the computer executes the method 900, and / or executes the method 1100, and / or executes the control method of the HOE lens.

[0154] The embodiment of the present application also provides a computer-readable storage medium, the computer-readable medium storing program codes for execution by a device, the program codes comprising instructions for executing the method 900, and / or instructions for executing the method 1100, and / or instructions for executing the control method of the HOE lens.

[0155] The embodiment of the present application also provides a chip, the chip comprising a processor and a data interface, the processor reading instructions stored on a memory through the data interface, and executing the method 900, and / or executing the method 1100, and / or executing the control method of the HOE lens.

[0156] Optionally, as an implementation manner, the chip can further comprise a memory, the memory storing instructions, and the processor being configured to execute the instructions stored on the memory, and when the instructions are executed, the processor is configured to execute the method 900, and / or execute the method 1100, and / or execute the control method of the HOE lens.

[0157] Those skilled in the art can clearly understand that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to realize the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0158] Those skilled in the art can clearly understand that, for the convenience and brevity of the description, the specific working processes of the above-described system, device and unit can refer to the corresponding processes in the foregoing method embodiments, which will not be repeated here.

[0159] In several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other ways. For example, the above-described device embodiments are only schematic, for example, the division of the units is only a logical function division, and actual implementation can have another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or other forms.

[0160] The units described as separate components can or can not be physically separated, and the components shown as units can or can not be physical units, that is, they can be located in one place, or can be distributed on a plurality of network units. According to actual needs, some or all of the units can be selected to achieve the purpose of the embodiment.

[0161] In addition, each functional unit in each embodiment of the present application can be integrated into a processing unit, or each unit can exist physically independently, or two or more units can be integrated into one unit.

[0162] If the functions are implemented in the form of software function units and sold or used as independent products, they can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application essentially or the parts that contribute to the prior art or parts of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various media that can store program codes.

[0163] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A head-up display device, characterized by comprising: The application relates to a variable-focus holographic optical element (HOE) lens and an image projection device. The HOE lens is attached to a light-transmitting plane, and the working time sequence of the HOE lens comprises N time periods, the HOE lens corresponds to different focal lengths and different deflection angles in the N time periods respectively, wherein N is a positive integer greater than or equal to 2. The image projection device comprises an image generation module (PGU) and an optical lens group, the PGU is used for generating N projection images corresponding to the N time periods, the optical lens group is used for projecting the N projection images to the HOE lens, reflecting the N projection images through the HOE lens, and focusing virtual images of the N projection images to different depths outside the light-transmitting plane by controlling the switching frequency of the N time periods. The preparation method of the HOE lens is as follows:

2. The apparatus of claim 1, wherein, A parallel laser and a focused laser with a deflection angle are used to interfere with each other on a polymer dispersed liquid crystal (PDLC) holographic dry plate to obtain the HOE film; M layers of the HOE film are laminated to obtain the HOE lens, wherein each layer of the M layers is prepared by using focused laser with different focal lengths and different deflection angles. The HOE lens comprises M layers of HOE films, and M is a positive integer; the HOE film has at least two film states, the film states comprise a transparent state and a diffraction state, and by respectively controlling the film states of each layer of the HOE film, the HOE lens corresponds to different focal lengths and different deflection angles in the N time periods.

3. The apparatus of claim 1 or 2, wherein, The HOE film is loaded with a square wave voltage, when the voltage is 0, the HOE film is in the diffraction state, and when the voltage is not 0, the HOE film is in the transparent state.

4. The apparatus of claim 3, wherein, If the film state of the HOE film is the transparent state, the HOE film does not have a focusing function and does not have a deflection angle; 5. The apparatus of claim 3 or 4, wherein, If the film state of the HOE film is the diffraction state, the HOE film has a focusing function and has a deflection angle. Each layer of the M layers of the HOE film has different focal lengths and different deflection angles when being in the diffraction state.

6. The apparatus of claim 3 or 4, wherein, The deflection angle of the HOE film in the diffraction state is 2-15 degrees, and the deflection angle of the HOE lens is the sum of the deflection angles of all the HOE films in the diffraction state in the M layers of the HOE film.

7. The apparatus of claim 5, wherein, The virtual images of the N projection images do not overlap each other.

8. The apparatus of claim 6 or 7, wherein, The relationship of M and N is: N=2 M .

9. The device of any one of claims 1 to 8, wherein, By controlling the focal length, the deflection angle and the deflection direction of the HOE lens in each time period of the N time periods, the virtual images of the N projection images are focused to different depths outside the light-transmitting plane.

10. The device of any one of claims 1 to 9, wherein, The N projection images comprise a first projection image and a second projection image, the first projection image is used for displaying instrument information, and the second projection image is used for displaying augmented reality image information.

11. The device of any one of claims 1 to 10, wherein, The PGU is configured to generate the second projection image when the voltage loaded on the HOE film is 0, the second projection image is imaged on a B screen at a first depth, and the PGU generates the first projection image when the voltage loaded on the HOE film is not 0, the first projection image is imaged on an A screen at a second depth, and the first depth is greater than the second depth.

12. The apparatus of claim 11, wherein, ​ 13. The apparatus of claim 12, wherein, The HOE film is loaded with a square wave voltage with a frequency greater than 24 Hz, so that the driver simultaneously observes the virtual images at the A screen and the B screen, and the virtual image of the A screen and the virtual image of the B screen do not overlap.

14. The apparatus of any one of claims 3 to 13, wherein, The HOE film is prepared by any one of an exposure method, an electron beam lithography method or a nanoimprint method.

15. The apparatus of any one of claims 3 to 13, wherein, The device further comprises: a controller for controlling the PGU to generate N projection images corresponding to the N time periods; and / or, controlling the film state of each layer of the HOE film, so that the HOE lens corresponds to different focal lengths and different deflection angles respectively in the N time periods.

16. The device of any one of claims 1 to 13, wherein, The unit time includes K working periods, each working period includes the N time periods, and K is greater than or equal to a preset threshold.

17. The device of any one of claims 1 to 13, wherein, The optical mirror group comprises: a plane mirror and a curved mirror, which are located between the HOE lens and the PGU, and the N projection images are reflected to the HOE lens through the plane mirror and the curved mirror.

18. A head-up display method characterized by comprising: The head-up display method is implemented in a head-up display device, which comprises a variable-focus holographic optical element (HOE) lens and an image projection device. The HOE lens is attached to a light-transmitting plane, and the working time sequence of the HOE lens includes N time periods, and the HOE lens corresponds to different focal lengths and different deflection angles respectively in the N time periods, wherein N is a positive integer greater than or equal to 2. The image projection device comprises an image generation module (PGU) and an optical mirror group, and the PGU is used to generate N projection images corresponding to the N time periods. The head-up display method comprises: projecting the N projection images to the HOE lens through the optical mirror group, reflecting through the HOE lens, and controlling the switching frequency of the N time periods, so that the virtual images of the N projection images are focused at different depths outside the light-transmitting plane.

19. The method of claim 18, wherein, The preparation method of the HOE lens is as follows: a parallel laser beam and a focused laser beam with a deflection angle are used to interfere with each other on a polymer dispersed liquid crystal (PDLC) holographic plate to obtain the HOE film; M layers of the HOE film are stacked to obtain the HOE lens, wherein each layer of the M layers is prepared by using focused laser beams with different focal lengths and different deflection angles.

20. The method of claim 18 or 19, wherein, The HOE lens comprises M layers of HOE films, and M is a positive integer; the HOE film has at least two film states, including a transparent state and a diffraction state, and by respectively controlling the film state of each layer of the HOE film, the HOE lens corresponds to different focal lengths and different deflection angles respectively in the N time periods.

21. The method of claim 20, wherein, The HOE film is loaded with a square wave voltage, and when the voltage is 0, the HOE film is in the diffraction state, and when the voltage is not 0, the HOE film is in the transparent state.

22. The method of claim 20 or 21, wherein, If the film state of the HOE film is the transparent state, the HOE film does not have a focusing function and does not have a deflection angle. If the film state of the HOE film is the diffraction state, the HOE film has a focusing function and has a deflection angle.

23. The method of claim 20 or 21, wherein, Each of the M HOE films has a different focal length and a different deflection angle when in a diffractive state.

24. The method of claim 23, wherein, The deflection angle of the HOE film when in a diffractive state is 2° to 15°, and the deflection angle of the HOE lens is the sum of the deflection angles of all the HOE films in the M HOE films when in a diffractive state.

25. The method of claim 23 or 24, wherein, The relationship of M and N is: N=2 M .

26. The method of any one of claims 18 to 25, wherein, The virtual images of the N projected images do not overlap with each other.

27. The method of any one of claims 18 to 26, wherein, The focal length, the deflection angle, and the deflection direction of the HOE lens at each of the N time periods are controlled so that the virtual images of the N projected images are focused at different depths outside the light-transmitting plane.

28. The method of any one of claims 18 to 27, wherein, The N projected images include a first projected image and a second projected image, the first projected image is used to display instrument information, and the second projected image is used to display augmented reality image information.

29. The method of claim 28, wherein, The PGU is configured to generate the second projected image when the voltage loaded on the HOE film is 0, the second projected image being imaged at a B screen at a first depth; generate the first projected image when the voltage loaded on the HOE film is not 0, the first projected image being imaged at an A screen at a second depth; and the first depth is greater than the second depth.

30. The method of claim 29, wherein, The frequency of the square wave voltage loaded on the HOE film is greater than 24 Hz, so that the driver simultaneously observes the virtual images at the A screen and the B screen, and the virtual images of the A screen and the virtual images of the B screen do not overlap.

31. The method of any one of claims 20 to 30, wherein, The HOE film is prepared by any one of an exposure method, an electron beam lithography method, or a nanoimprint method.

32. The method of any one of claims 20 to 30, wherein, Each working cycle includes the N time periods, and K is greater than or equal to a preset threshold value.

33. The method of any one of claims 18 to 30, wherein, The optical mirror group includes: A plane mirror and a curved mirror, the plane mirror and the curved mirror being located between the HOE lens and the PGU, and the N projected images being reflected to the HOE lens through the plane mirror and the curved mirror.

34. A vehicle characterized by The head-up display device includes any one of claims 1 to 17.

35. An in-vehicle system, characterized by comprising: The head-up display device includes any one of claims 1 to 17.

36. A computer readable medium, characterized in that, A computer program for storing, the computer program including a computer program for executing the head-up display method of any one of claims 18 to 33. A computer program for storing, the computer program including a computer program for executing the head-up display method of any one of claims 18 to 33.

Images