Head-up display device

Abstract

This application discloses a head-up display device for use in a vehicle. The head-up display device includes: an image generation unit for generating an image beam and emitting the image beam to a light modulation element; the light modulation element is located on the light-emitting side of the image generation unit and is used to modulate the image beam and emit the modulated image beam to a micro-optical element; the micro-optical element includes multiple regions, the multiple regions including at least a first effective region, the first effective region being used to reflect the image beam to the human eye; the multiple regions also include a target region, the transmittance of the target region being higher than the transmittance of the first effective region.

Description

Head-up display

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the Intellectual Property Office of the People's Republic of China on February 28, 2024, with application number 202410223836.1 and application name "A head-up display device", the entire contents of which are incorporated by reference into this application; this application claims priority to the Chinese patent application filed with the Intellectual Property Office of the People's Republic of China on March 6, 2024, with application number 202410252801.0 and application name "A head-up display device", the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The embodiments of the present application relate to projection display technology, and more particularly to a head-up display device. Background Art

[0004] A head-up display (HUD) is a widely used display device in driving scenarios. For example, it is used in vehicles, ships, airplanes and other means of transportation to display information such as speed and navigation, eliminating the need for drivers to look down, thereby improving safety.

[0005] Head-up displays typically use a secondary optical imaging solution for projection. Specifically, the head-up display includes an image generation unit, a first free-form mirror, and a second free-form mirror. The image generated by the image generation unit is deflected by the secondary optical elements, namely the first and second free-form mirrors, and then converges into the human eye through the windshield. Summary of the Invention

[0006] According to a first aspect of an embodiment of the present application, a head-up display device is provided for use in a vehicle. The head-up display device includes:

[0007] An image generating unit, configured to generate an image beam and emit the image beam to a light modulating element;

[0008] The light modulation element is located on the light-emitting side of the image generation unit, and is used to modulate the image light beam and emit the modulated image light beam to the micro-optical element;

[0009] The micro-optical element includes multiple areas, the multiple areas include at least a first effective area, the first effective area is used to reflect the image light beam to the human eye; the multiple areas also include a target area, the transmittance of the target area is higher than the transmittance of the first effective area.

[0010] According to a second aspect of an embodiment of the present application, a head-up display device is provided for use in a vehicle. The head-up display device includes:

[0011] An image generating unit, configured to generate and emit an image beam;

[0012] a first diffractive optical element, located at a light-emitting side of the image generating unit, for diffracting the image beam and emitting the diffracted image beam to a second diffractive optical element;

[0013] The second diffractive optical element is used to reflect the image light beam emitted by the first diffractive optical element to the eye box area to form a target virtual image. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG1 is a structural schematic diagram of a head-up display device;

[0015] FIG2 is a schematic diagram of an eye box region;

[0016] FIG3 is a schematic diagram of an eye located at the edge of an eye box;

[0017] FIG4 is a schematic diagram of the principle of a diffusion membrane;

[0018] FIG5 is a schematic diagram of a head-up display device and a diffusion film;

[0019] FIG6 is a second structural diagram of a head-up display device;

[0020] FIG7 is a schematic diagram of an application scenario of a head-up display device provided in an embodiment of the present application;

[0021] FIG8 is a schematic diagram of a structure of a head-up display device according to an embodiment of the present application;

[0022] FIG9 is a schematic diagram of a first effective area arrangement according to an embodiment of the present application;

[0023] FIG10 is a second schematic diagram of an arrangement of a first effective area provided in an embodiment of the present application;

[0024] FIG11 is a schematic diagram of a micro-optical element provided by an embodiment of the present application, wherein the micro-optical element includes a first active area and an inactive area, and reflects an image beam toward a human eye;

[0025] FIG12 is a schematic diagram of a micro-optical element reflecting an image beam to a human eye when all micro-optical elements provided by an embodiment of the present application are in an active area;

[0026] FIG13 is a schematic diagram of the arrangement of a first active area and a second active area provided in an embodiment of the present application;

[0027] FIG14 is a second structural diagram of a head-up display device provided in an embodiment of the present application;

[0028] FIG15 is a schematic diagram of the structure of a holographic film provided in an embodiment of the present application;

[0029] FIG16 is a schematic diagram of a reconstruction based on a holographic film according to an embodiment of the present application;

[0030] FIG17 is a schematic diagram of the transmission of an image beam in a head-up display device provided in an embodiment of the present application;

[0031] FIG18 is a schematic diagram showing the principle of forming a virtual image by a first diffractive optical element and a second diffractive optical element according to an embodiment of the present application;

[0032] FIG19 is a third structural diagram of a head-up display device provided in an embodiment of the present application;

[0033] FIG20 is a schematic diagram of a light intensity distribution curve after passing through a first diffractive optical element provided in an embodiment of the present application;

[0034] FIG21 is a fourth structural diagram of a head-up display device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0035] In order to make the purpose, implementation mode and advantages of the present application clearer, the exemplary implementation mode of the present application will be clearly and completely described below in conjunction with the drawings in the exemplary embodiments of the present application. Obviously, the described exemplary embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0036] In recent years, laser projection has been widely used due to its advantages, including a wide color gamut, high light efficiency, and eye protection. However, with market development, the demand for projection displays continues to increase, and various display technologies continue to innovate, leading to the widespread use of head-up displays.

[0037] Head-up displays (HUDs), also known as head-up display systems, can be used in vehicles such as automobiles, ships, and aircraft. For example, a HUD can project important driving information, such as speed, RPM, and navigation, onto the windshield. The driver can view the corresponding image directly in front of the windshield, effectively avoiding the potential driving risks of looking down to observe driving information and losing sight of road conditions, thereby improving driving safety.

[0038] Figure 1 is a schematic diagram of the structure of a head-up display device. As shown in Figure 1, head-up display device 101 includes an image generation unit 1011, a diffusion film 1012, a first free-form surface mirror 1013, and a second free-form surface mirror 1014. Head-up display device 101 utilizes a secondary optical imaging solution. Specifically, image generation unit 1011 projects an image onto diffusion film 1012. After passing through diffusion film 1012, the image beam angle increases. After passing through the secondary imaging element, the first free-form surface mirror 1013 and the second free-form surface mirror 1014 deflect the image, which enters the human eye through windshield 102, forming a virtual image S1 at a distance of approximately 10 meters in the far field. The image perceived by the human eye is this virtual image. The light source used in the secondary optical imaging solution is mostly an LED light source.

[0039] Because a vehicle may shake during travel due to road conditions and other factors, the position of the human eye may also change accordingly. However, under normal circumstances, the area where the human eye moves is relatively fixed. The area within a certain range where the human eye can see the image projected by the head-up display device 101 is called the eye box, as shown in Figure 2. Figure 2 is a schematic diagram of the eye box area. The eye box area is the range formed by ABCD. In Figure 2, the eye is located at the center of the eye box. At this time, the eye can move left, right, up, or down. Within the eye box range, the eye can see the far-field virtual image. In this case, refer to Figure 3, which is a schematic diagram of the eye at the edge of the eye box.

[0040] The diffusion film 1012, serving as the PGU imaging surface, is a diffuser with a diffusion function. It is primarily used to increase the angle of the beam formed by the image generating unit 1011, thereby increasing the angle of the projected image and, in turn, the viewing angle of the human eye within the eye box. For details, see Figures 4 and 5. Figure 4 is a schematic diagram of the principle of a diffusion film. After the light beam emitted by the image generating unit 1011 passes through the diffusion film 1012, the angle of the beam is expanded to a maximum of 2.

[0041] The human eye, located at different positions within the eye box, can correspond to images formed by different light beams. For example, in the horizontal direction, light beams l1, l4, and l7 shown in Figure 4 correspond to one image, corresponding to the left side of the eye box. This means that the human eye at this position can see the images formed by light beams l1, l4, and l7. Light beams l2, l5, and l8 correspond to one image, corresponding to the middle of the eye box. Light beams l3, l6, and l9 correspond to one image, corresponding to the right side of the eye box. The vertical direction corresponds to the top, middle, and bottom parts of the eye box. The principles behind this are essentially the same as those for horizontal imaging and will not be elaborated upon here.

[0042] Figure 5 is a schematic diagram of the principles of a diffuser film in a head-up display device. The head-up display device shown in Figure 5 also includes a projection lens 103. The light beam emitted by the image generation unit 1011 is converged by the projection lens 103 and then incident on the diffuser film 1012. The diffuser film 1012 further increases the angle of the light beam. As can be seen from Figures 4 and 5, this increased angle of the light beam after passing through the diffuser film 1012 increases the viewing range of the human eye.

[0043] As can be seen above, the image generation unit 1011 projects the image onto the PGU imaging surface. To increase the viewing angle for the human eye, the PGU imaging surface typically utilizes a diffuser sheet, or diffusion film 1012, with a diffusion function. Because the image formed on diffusion film 1012 is real, the distance between the image generation unit 1011 and diffusion film 1012 is the distance between the object and the image. This relatively long distance requires the head-up display device to encompass the object-image distance, resulting in a relatively large head-up display device, approximately 20L overall. However, the limited space in the cab of a typical vehicle makes the head-up display device unsuitable for installation, making it unsuitable for some vehicle models.

[0044] Figure 6 is a second schematic diagram of the structure of a head-up display device, which includes an image generation unit 601, a diffusion film 602, and a micro-optical element 603. Image generation unit 601 emits an image beam, which is projected onto diffusion film 602. The beam corresponding to the image has its angle increased after passing through diffusion film 602. This increased beam is then reflected by micro-optical element 603 into the eye box, forming a distant virtual image S2 at the eye. Compared to the head-up display device described above using a first free-form surface mirror and a second free-form surface mirror, this eliminates the need for a secondary imaging system and reduces its size. Furthermore, the use of micro-optical element 603 to modulate the beam allows for improvements based on the image beam, increasing its reflection efficiency.

[0045] The micro-optical element 603 can be equivalent to a free-form mirror or a Fresnel reflector. Because the micro-optical element 603 needs to reflect the image beam, its light transmittance is relatively low. If a windshield has a minimum light transmittance requirement, the micro-optical element 603 may not be used on the windshield, limiting the application range of the head-up display device.

[0046] Based on this, the present application provides a head-up display device comprising an image generation unit, a light modulation element, and a micro-optical element, wherein the micro-optical element includes multiple regions, including at least a first effective region and a target region. The first effective region reflects the received image beam to the human eye, and the human eye sees the image corresponding to the image beam. The transmittance of the target region is higher than that of the first effective region. The provision of the target region increases the overall transmittance of the micro-optical element, so that the micro-optical element meets the minimum transmittance requirement of the windshield, thereby expanding the application range of the micro-optical element.

[0047] Figure 7 is a schematic diagram of an application scenario of a head-up display device provided in an embodiment of the present application. Referring to Figure 7, based on the head-up display device, driving information such as speed and navigation can be projected far away on the outside of the windshield. During driving, the driver can view the projected driving information in real time while watching the road conditions, without having to lower his head to check, which is safer.

[0048] FIG8 is a schematic diagram of a structure of a head-up display device provided in an embodiment of the present application, which is applied to a vehicle, including but not limited to a car, a ship, an airplane, etc. Referring to FIG8 , the head-up display device includes:

[0049] The image generating unit 801 is used to generate an image beam and emit the image beam to the light modulating element 802;

[0050] The light modulating element 802 is located on the light-emitting side of the image generating unit 801 and is used to modulate the image beam and emit the modulated image beam to the micro-optical element 803;

[0051] The micro-optical element 803 includes multiple areas, including at least a first effective area A for reflecting the image beam to the human eye; and a target area T having a higher transmittance than the first effective area A.

[0052] In one implementation scenario, the image generation unit 801 can be regarded as a small projector, and its principle is basically the same as the principle of a projector to achieve projection, and can generally include a light source, an optical machine, and a projection lens.

[0053] The light source is used to provide an illumination beam, and can be an LED light source or a laser light source.

[0054] The laser light source can be a monochromatic laser, a dual-color laser, or a tri-color laser. For example, a tri-color laser emitting the three primary colors of red, green, and blue is used as an example. It can be a combination of independent lasers emitting red, green, and blue, or a packaged assembly including laser chips emitting red, green, and blue. The red, green, and blue laser chips can be packaged in an array arrangement, such as a 4x5 array, a 3x5 array, or a 2x7 array. The number and arrangement of laser chips of different colors can be set according to actual needs and are not limited in this application.

[0055] The optical engine includes a light valve modulation device, which includes but is not limited to DMD (Digital Micromirror Device), LCOS (Liquid Crystal On Silicon), LCD (Liquid Crystal Display), etc.

[0056] Among them, DMD is a reflective light valve device, which is used in the DLP (Digital Light Processing) projection architecture. It is driven by an electrical signal to modulate the light beam so that the light beam carries image information, that is, an image beam is obtained. The surface of the DMD includes thousands of tiny mirrors, and each tiny mirror can be driven individually for deflection. For example, each tiny mirror can be deflected by plus or minus 12 degrees or plus or minus 17 degrees. Among them, the light emitted at a positive deflection angle is called ON light; the light reflected at a negative deflection angle is called OFF light. OFF light is invalid light, which is usually incident on the housing or absorbed by a light absorbing device. ON light is an effective light beam that is irradiated by the tiny mirrors on the surface of the DMD and is incident on the projection lens through a positive deflection angle for projection imaging.

[0057] Taking the DLP projection architecture as an example, the image generation unit 10 may also include an image processing chip and a DMD driver control chip. The DMD driver control chip may be integrated with the DMD or exist independently. Specifically, the image processing chip decomposes the image to be displayed into RGB three-color component images and outputs each R, G, or B component image signal to the DMD driver control chip. The DMD driver control chip converts the component image signals into drive signals for the DMD, which accumulates the brightness of a primary color component image by controlling the angle and duration of the deflection of the tiny reflectors. By superimposing multiple primary color component image frames and utilizing the persistence of vision effect of the human eye, a color image can be formed.

[0058] Because the drive signals received by the DMD are generated based on the RGB primary color components of the image to be displayed, when the DMD receives a drive signal corresponding to the R primary color component, the DMD should be illuminated by red light. Similarly, when the DMD receives a drive signal corresponding to the G or B primary color components, the DMD should be illuminated by green or blue light. Therefore, the light source needs to synchronize with the DLP system to output the illumination beam of the color required by the DMD.

[0059] The light modulator 802 is used to modulate light, which can increase the transmission angle of the image beam, realize the diffusion of the image beam, and further increase the range of the eye box, so that the human eye can see the virtual image corresponding to the image beam within a larger range, which is beneficial to improving the user experience.

[0060] In one implementation scenario, the light modulation element 802 includes but is not limited to a diffusion film, a holographic film or an element with a microstructure, wherein the element with a microstructure can be prepared by a nanoimprinting method, and the microstructure includes but is not limited to triangular, cylindrical, rectangular and other structures.

[0061] In some embodiments, the micro-optical element 803 is a holographic film or a microstructured element, and may include multiple regions. The first active region A of the multiple regions can reflect the image beam toward the human eye, forming a magnified virtual image in the far field. The image perceived by the human eye is the virtual image. For holographic films, light is processed using a photopolymer; in this case, the first active region A can be a region containing the photopolymer. For microstructured elements, the first active region A can be a region having the microstructure.

[0062] In one implementation scenario, the micro-optical element 803 may be located on the windshield of a vehicle. Specifically, it may be located in the interlayer of the windshield, or attached to the surface of the windshield by means of film or coating.

[0063] In some embodiments, there are multiple first active areas A, and they are arranged periodically.

[0064] In one implementation scenario, the micro-optical element 803 includes multiple first active areas A arranged in an array along a first direction and a second direction, wherein the first direction is perpendicular to the second direction. The array arrangement may be a manner in which the multiple first active areas A are arranged in a certain order.

[0065] FIG9 is a first schematic diagram of an arrangement of first active areas according to an embodiment of the present application. Referring to FIG9 , the smaller rectangles shown in FIG9 are all first active areas A. Due to the large number of first active areas, not all are marked. Except for the first active areas A, the remaining areas in the micro-optical element 803 are target areas T. The first direction may be the X direction shown in FIG9 , and the second direction may be the Y direction shown in FIG9 .

[0066] A row arranged along the Y direction is called a column, and a row arranged along the X direction is called a row. For different rows, the arrangement of the multiple first active areas A of the current row is the same as the arrangement of the multiple first active areas A of the previous row.

[0067] Based on the multiple first active areas A shown in Figure 9, a first active area A' shown in Figure 9 is used for illustration, and the distance m between the first active area A' and the first active area A adjacent to it in the first direction is equal to the distance n between the first active area A adjacent to it in the second direction.

[0068] In another implementation scenario, still using the first active area A' for illustration, the distance m between the first active area A' and the first active area A adjacent thereto in the first direction and the distance n between the first active area A adjacent thereto in the second direction may not be equal.

[0069] In another implementation scenario, in addition to the arrangement of multiple first effective areas A shown in Figure 9, other array arrangements can also be used, as shown in Figure 10. Figure 10 is a second schematic diagram of an arrangement of the first effective areas provided in an embodiment of the present application. At this time, there is a certain misalignment in the arrangement of the multiple first effective areas A contained in two adjacent rows.

[0070] Taking part of the first effective area A for illustration, the dotted line l1 and the dotted line l2 in FIG10 both pass through multiple first effective areas A. The dotted line l1 and the dotted line l2 are parallel and form a certain angle with the X direction or the Y direction, that is, the multiple first effective areas A passed by the dotted line l1 and the multiple first effective areas A passed by the dotted line l2 are arranged in parallel.

[0071] In some embodiments, the shape of the first active area A is at least one of a circle, a rectangle, a triangle, and an irregular polygon. The first active area A shown in Figures 9 and 10 is a rectangle. In addition to the shapes shown above, the first active area A may also have other shapes, which are not limited in this application.

[0072] An embodiment of the present application provides a head-up display device, including an image generation unit 801, a light modulation element 802, and a micro-optical element 803. The image generation unit 801 generates and emits an image beam, and the light modulation element 802 modulates the image beam and emits the modulated image beam to the micro-optical element 803. Based on the first effective area A among the multiple areas included in the micro-optical element 803, the image beam is reflected toward the human eye, so that the human eye sees a virtual image corresponding to the image beam. At the same time, because the multiple areas included in the micro-optical element 803 of the present application also include a target area T, and the transmittance of the target area T is higher than the transmittance of the first effective area A, the overall transmittance of the micro-optical element 803 is increased based on the target area T, thereby ensuring that the transmittance of the micro-optical element 803 meets the minimum transmittance requirement of the windshield. The micro-optical element 803 can be used on windshields, expanding the application range of the head-up display device.

[0073] In one or more embodiments of the present application, if the transmittance of the target area T is higher than a first preset threshold, and the first preset threshold is greater than the transmittance of the first effective area A, the target area T is an invalid area for transmitting light.

[0074] The inactive area is used to transmit light and cannot reflect the image beam to the human eye. For example, using micro-optical element 803 as an element having a microstructure, the inactive area is the area of ​​micro-optical element 803 that does not have a microstructure. As shown in Figures 9 and 10 , in one implementation scenario, the target area T included in micro-optical element 803 in Figures 9 and 10 is the inactive area.

[0075] FIG11 is a schematic diagram of a micro-optical element provided by an embodiment of the present application, wherein the micro-optical element includes a first active area and an inactive area, and reflects an image beam to the human eye. Referring to FIG11 , the target area T is an inactive area. Since the inactive area cannot reflect the image beam, it can only be reflected by multiple first active areas A. The human eye can receive the light beams emitted by multiple first active areas A. At the same time, because the first active areas A are closely arranged and the light intervals are small, the human eye can see the projected image at different positions without affecting the imaging of the head-up display device. The inactive area can be observed normally, and while achieving projection, the light transmittance of the micro-optical element 803 is also effectively improved, allowing the micro-optical element 803 to be used on windshields.

[0076] The aperture ratio can be used to represent the ratio of the active area to the overall area. In one implementation scenario, the micro-optical element 803 includes a first active area A and an inactive area. The ratio of the area of ​​the first active area A to the area of ​​the micro-optical element 803 is greater than 30% or less than 70%, i.e., the aperture ratio is greater than 30% or less than 70%. In this case, the area of ​​the micro-optical element 803 is the sum of the area of ​​the first active area A and the area of ​​the inactive area.

[0077] It should be noted that, if there are multiple first active areas A, the area of ​​the first active area A included in the micro-optical element 803 is the sum of the areas of the multiple first active areas A.

[0078] In some embodiments, the micro-optical element 803 is located on a windshield of a vehicle, and a ratio of an area of ​​the first active region A included in the micro-optical element 803 to an area of ​​the windshield is less than or equal to 30%.

[0079] Since the transmittance of the first active area A is relatively low, it will affect the transmittance of the windshield. In this case, the ratio of the area of ​​the first active area A to the area of ​​the windshield is less than or equal to 30%. At the same time, there are inactive areas of light transmission between the multiple first active areas A, thereby effectively avoiding the influence of the micro-optical element 803 on the transmittance of the windshield.

[0080] In summary, the micro-optical element 803 comprises a first active area A and an inactive area. The first active area A reflects the image beam toward the human eye, allowing the user to see the image projected by the head-up display. Meanwhile, the inactive area transmits light, allowing the scene outside the windshield to be normally observed. This improves the light transmittance of the micro-optical element 803, meeting the minimum light transmittance requirement for windshields. This allows the micro-optical element 803 to be used on windshields, expanding the application range of head-up displays.

[0081] In one or more embodiments of the present application, if the transmittance of the target area T is higher than the second preset threshold, the second preset threshold is greater than the transmittance of the first effective area A and less than the first preset threshold, the target area T is the second effective area, which is used to reflect the image beam to the human eye.

[0082] Taking micro-optical element 803 as an example, since the second active area can reflect the image beam toward the human eye, the second active area also has a microstructure, and the image beam incident on this area is reflected based on the microstructure. In one implementation scenario, still referring to Figures 9 and 10, the target areas T included in micro-optical element 803 in Figures 9 and 10 can all be second active areas. In this case, the first active areas A are arranged periodically, and the remaining area of ​​micro-optical element 803 serves as the second active area.

[0083] Since both the first effective area A and the second effective area can reflect the image light beam to the human eye, the first effective area A and the second effective area are both effective areas. Figure 12 is a schematic diagram of a micro-optical element reflecting the image light beam to the human eye when both micro-optical elements provided in an embodiment of the present application are effective areas. The light modulation element 802 expands the angle of the image light beam, which is reflected into the human eye through the micro-optical element 803. The reflection angle is large, so that all image light beams incident at multiple angles can be reflected into the human eye, with high efficiency.

[0084] Since the transmittance of the second effective area is higher than the second preset threshold, and the second preset threshold is greater than the transmittance of the first effective area A, the transmittance of the second effective area is greater than the transmittance of the first effective area A. Compared with the first effective area A, the second effective area can also reflect the image light beam to the human eye. At the same time, the transmittance is higher, so the impact on the transmittance of the windshield is relatively small, and the minimum transmittance requirement of the windshield can be met.

[0085] Continuing with the example of the micro-optical element 803 as an element having a microstructure, different microstructures, their sizes, gaps between microstructures, and the like may affect the light transmittance of the micro-optical element 803. Therefore, by providing a microstructure in the second active area, the light transmittance of the second active area can be made greater than that of the first active area A while still being able to reflect the image beam to the human eye.

[0086] In one implementation scenario, the transmittance of different second effective areas may be different. Similarly, the transmittance of different first effective areas A may also be different. In this case, the second preset threshold may be greater than the maximum transmittance of multiple first effective areas A.

[0087] In some embodiments, the first effective area A and the second effective area can also be arranged periodically. Figure 13 is a schematic diagram of the arrangement of the first effective area and the second effective area provided in an embodiment of the present application. Referring to Figure 13, the first effective area A is a small rectangle composed of solid lines. Since the number of first effective areas A is large, not all of them are marked. The target area T is a small rectangle composed of dotted lines. At this time, the target area T is the second effective area. A row arranged along the Y-axis direction is called a column, and the first effective area A and the second effective area are cross-arranged according to the columns. Specifically, from left to right, the first column is the first effective area A, the second column is the second effective area, the third column is the first effective area A, the fourth column is the second effective area, and so on.

[0088] In addition to the arrangement shown in FIG13 , the first column may be the first effective area A, the second and third columns may be the second effective area, the fourth column may be the first effective area A, the fifth and sixth columns may be the second effective area, and so on.

[0089] In another implementation scenario, a row arranged along the X-axis direction is called a row, and the first valid area A and the second valid area can also be arranged crosswise according to rows. Specifically, from top to bottom, the first row and the second row are the first valid area A, the third row and the fourth row are the second valid area, the fifth row and the sixth row are the first valid area A, and so on.

[0090] Alternatively, each row or each column includes a first effective area A and a second effective area. Furthermore, in each row or each column, the first effective area A and the second effective area are also arranged in a certain period, etc. For example, for the same row, the first effective area A and the second effective area alternate in sequence, or the first effective area A is on the left and the second effective area is on the right, etc.

[0091] The above only illustrates several exemplary arrangements of the first effective area A and the second effective area. They can also be arranged in other ways. The arrangement can be set according to actual needs and this application does not impose any restrictions on this.

[0092] The shape of the second effective area may also be a rectangle, a triangle, a circle, an irregular polygon, or other shapes, and this application does not impose any limitation on this.

[0093] The ratio of the sum of the areas of the first active area A and the second active area to the area of ​​the micro-optical element 803 is 100%.

[0094] Since both the first active area A and the second active area are active areas, the areas encompassed by the micro-optical element 803 are all active areas. The area of ​​the micro-optical element 803 is the sum of the areas of the first active area A and the second active area. Therefore, the ratio of the sum of the areas of the first active area A and the second active area to the area of ​​the micro-optical element 803, i.e., the aperture ratio, is 100%. Since there are multiple first active areas A and multiple second active areas, the area of ​​the first active area A is the sum of the areas of the multiple first active areas A, and the area of ​​the second active area is the sum of the areas of the multiple second active areas.

[0095] In some embodiments, the target area T in the micro-optical element 803 may include an invalid area and a second effective area. That is, the micro-optical element 803 includes a first effective area A, a second effective area, and an invalid area. The arrangement thereof is not limited as long as the light transmittance requirement of the windshield is met.

[0096] In summary, the target area T included in the micro-optical element 803 is the second effective area. The second effective area can reflect the image light beam to the human eye to form a virtual image, and its transmittance is greater than the transmittance of the first effective area A. Therefore, based on the second effective area, the overall transmittance of the micro-optical element 803 is improved, thereby reducing the impact on the transmittance of the windshield, and can meet the minimum transmittance requirement of the windshield. Therefore, the micro-optical element 803 can be installed on the windshield, expanding the application range of the head-up display device.

[0097] FIG14 is a second schematic diagram of the structure of a head-up display device provided in an embodiment of the present application. The head-up display device is applied to a vehicle, specifically, the cab of the vehicle, which also has a windshield through which the driver can see the outside scenery and road conditions. The vehicle includes but is not limited to various vehicles, such as gasoline vehicles, electric vehicles, airplanes, ships, and other tools. Referring to FIG14 , the head-up display device includes:

[0098] An image generating unit 10, configured to generate and emit an image beam;

[0099] The first diffractive optical element 20 is located at the light-emitting side of the image generating unit 10 , and is configured to diffract the image beam and emit the diffracted image beam to the second diffractive optical element 30 .

[0100] The second diffractive optical element 30 is used to reflect the image light beam emitted by the first diffractive optical element 20 to the eye box area to form a target virtual image.

[0101] In some embodiments, the first diffractive optical element 20 and the second diffractive optical element 30 are holographic films, or elements with microstructures, wherein the elements with microstructures can be prepared by nanoimprinting.

[0102] The first diffractive optical element 20 and the second diffractive optical element 30 can both be holographic films, or both be elements with microstructures, or one can be a holographic film and the other a microstructured element. In addition to holographic films and elements with microstructures, the first diffractive optical element 20 and the second diffractive optical element 30 can also be HOEs (holographic optical elements) or other elements with diffraction functions, which is not limited in this application.

[0103] In one implementation scenario, if the first diffractive optical element 20 is a holographic film, FIG15 is a schematic diagram illustrating the construction of a holographic film according to an embodiment of the present application. Referring to FIG15 , a construction light source P emits a construction light beam 1, and a construction light source Q emits a construction light beam 2. Both construction light beams 1 and 2 are divergent beams. During the construction of the holographic film, construction light beams 1 and 2 interfere with each other, and this interference is recorded to form the holographic film. The bold line segments in FIG15 represent the holographic film.

[0104] Figure 16 is a schematic diagram of a holographic film-based reconstruction method provided by an embodiment of the present application. If the readout beam R coincides with one of the construction beams, as shown in Figure 16 , the readout beam R will diffract as it passes through the holographic film, just as it would from the construction light source Q. The image beam emitted by the image generation unit 10 of the present application serves as the readout beam and can be diffracted when passing through the first diffractive optical element 20.

[0105] The first diffractive optical element 20 can perform multi-level diffraction on the image beam, changing the transmission direction of the image beam while also increasing the angle of the image beam, thereby increasing the human eye's observation range, that is, increasing the eyebox range. In some embodiments, the target light emitted by the first diffractive optical element 20 increases the angle in the first direction by greater than 8° and / or less than 20°, and increases the angle in the second direction by greater than 2° and / or less than 8°, with the first direction and the second direction being perpendicular.

[0106] The target light is the edge light whose energy is reduced to 50% of the maximum energy of the image light beam emitted from the first diffractive optical element 20 .

[0107] In one implementation scenario, the image beam emitted by the first diffractive optical element may form a light spot, and the target light may be used to define the size and angle of the light spot. The target light may be a light beam whose energy is reduced to 50% of the maximum energy in the image beam as shown above. This ratio may be adjusted based on actual conditions and is not limited in this application.

[0108] The first and second directions can be defined based on the driver. For a driver sitting in the cab, the first direction is the direction of the line connecting the driver's two eyes. Referring to the eye box shown in FIG2 , the first direction is the direction AB or CD. The second direction is the direction perpendicular to the line connecting the driver's two eyes. Still referring to FIG2 , the second direction is the direction AC or BD.

[0109] In related art, a diffusion film can be used to increase the angle of the image beam. However, when the angle of the image beam is too large, some edge rays may not be incident on the free-form mirror, and thus cannot be reflected by the free-form mirror to be incident on the windshield, and then enter the human eye through the windshield, resulting in the edge rays not being effectively utilized. However, the present application uses the first diffractive optical element 20 to modulate the image beam. While increasing the image beam angle, it can also change the angle of the edge rays. While avoiding narrowing the eye box range, it can also ensure that the edge rays can be incident on the second diffractive optical element 30. The second diffractive optical element 30 reflects the edge rays and enters the human eye, which is beneficial for improving the utilization rate of the beam. For details, please refer to Figure 10.

[0110] FIG17 is a schematic diagram illustrating the transmission of an image beam in a head-up display device according to an embodiment of the present application. The initial angle between the marginal ray M and the principal ray N is α1, preventing the marginal ray M from being incident on the second diffractive optical element 30. After being modulated by the first diffractive optical element 20, the marginal ray M changes its transmission angle, bringing it closer to the principal ray N. At this point, the marginal ray M is located at the dotted line position shown in FIG17 . The angle between the marginal ray M and the principal ray N becomes α2, allowing the marginal ray M to be incident on the second diffractive optical element 30 and thereby enter the human eye.

[0111] After the first diffractive optical element 20 diffracts the image beam, it is then emitted through the first diffractive optical element 20. Because the angle of the emitted image beam increases, the inverse extension of the image beam converges to form a virtual image, which can be referred to as the first virtual image. Similarly, after the image beam is reflected by the second diffractive optical element 30 and enters the human eye, the inverse extension of the image beam also converges to form a virtual image, namely the target virtual image. The first virtual image and the target virtual image display the same content.

[0112] FIG18 is a schematic diagram illustrating the principle of forming a virtual image by a first diffractive optical element and a second diffractive optical element according to an embodiment of the present application. Referring to FIG18 , the first virtual image S1 is a virtual image formed by converging the inverse extension of the image beam emitted by the first diffractive optical element 20. Typically, the size of the first virtual image S1 is larger than that of the display chip.

[0113] Still referring to FIG18 , the image beam emitted by the first diffractive optical element 20 is incident on the second diffractive optical element 30. The target virtual image S2 is the virtual image formed by the image beam being reflected by the second diffractive optical element 30 and then converging along its extended lines. Since the second diffractive optical element 30 reflects the image beam toward the human eye (the position of the human eye is not shown in FIG18 ), the image perceived by the human eye is the target virtual image S2. Typically, the target virtual image S2 is larger than the second diffractive optical element 30, and the target virtual image S2 is also larger than the first virtual image S1.

[0114] Compared with the related art, the image light beam emitted by the image generating unit forms a real image on the diffusion film, and the head-up display device needs to meet the object distance and image distance. Since the first diffractive optical element 20 and the second diffractive optical element 30 both form virtual images, the image distance corresponding to the virtual image does not occupy or occupies a smaller space. The head-up display device only needs to consider the space occupied by the object distance. Therefore, the volume of the head-up display device can be reduced, and the miniaturization of the head-up display device can be achieved.

[0115] In some embodiments, the second diffractive optical element 30 may be located on the windshield of a vehicle. FIG19 is a third structural schematic diagram of a head-up display device according to an embodiment of the present application. Referring to FIG19 , the second diffractive optical element 30 is located within a layer of, or attached to, a windshield 40 of a vehicle.

[0116] In one implementation scenario, the second diffractive optical element 30 may be attached to the windshield 40 by means of filming or coating, and specifically, may be attached to the inner surface of the windshield 40 .

[0117] If the second diffractive optical element 30 is located on the vehicle's windshield 40, there is no need to consider the space occupied by the second diffractive optical element 30 within the vehicle's cab. As for the first diffractive optical element 20, the distance between the image generating unit 10 and the first diffractive optical element 20 is the object distance. This distance is shorter than the object-image distance between the image generating unit and the diffuser film, thus effectively reducing the size of the head-up display device.

[0118] It should be noted that FIG18 is only an illustrative illustration of the principle that the first diffractive optical element 20 forms the first virtual image S1 and the second diffractive optical element 30 forms the target virtual image S2, and does not limit the specific positions of the first diffractive optical element 20 and the second diffractive optical element 30.

[0119] In one implementation scenario, the first diffractive optical element 20 is located on the bottom side of the windshield 40, where the bottom side of the windshield 40 is the side of the windshield 40 closest to the steering wheel. Figure 20 is a schematic diagram of a light intensity distribution curve after passing through the first diffractive optical element, provided in an embodiment of the present application. The horizontal axis represents sin, θ represents the diffraction angle, and the vertical axis represents light intensity. As shown in Figure 20, after the first diffractive optical element 20 modulates the image beam, the intensity of the diffracted light of different orders is consistent, which improves the display effect.

[0120] The present application provides a head-up display device, comprising an image generation unit 10, a first diffractive optical element 20, and a second diffractive optical element 30. The first diffractive optical element 20 diffracts the image beam emitted by the image generation unit 10 and transmits the diffracted image beam to the second diffractive optical element 30. The second diffractive optical element 30 reflects the image beam emitted by the first diffractive optical element 20 to the eye box area, forming a target virtual image. The image seen by the human eye is the target virtual image. Since the image light beam of the present application can converge its reverse extension line to obtain a virtual image after passing through the first diffractive optical element 20, and the image light beam is reflected by the second diffractive optical element 30 and enters the human eye, what the human eye sees is also the virtual image obtained by the convergence of the reverse extension line of the image light beam. Compared with the image light beam emitted by the image generating unit forming a real image on the diffusion film, the head-up display device needs to meet the object distance and image distance. Since the image distance corresponding to the virtual image does not occupy or occupies a smaller space, the head-up display device only needs to consider the space occupied by the object distance, which is beneficial to reducing the volume of the head-up display device, realizing the miniaturization of the head-up display device, reducing the space in the cab occupied by the head-up display device, and being suitable for more types of vehicles, which is beneficial to expanding the scope of use of the head-up display device.

[0121] In one or more embodiments of the present application, the second diffractive optical element 30 is larger than the first diffractive optical element 20. Since the first diffractive optical element 20 increases the angle of the image beam and the image beam gradually diffuses as it is transmitted, the second diffractive optical element 30 needs to be larger than the first diffractive optical element 20 so that the second diffractive optical element 30 receives most of the image beam.

[0122] In one implementation scenario, the size of the second diffractive optical element 30 is greater than or equal to four times the size of the first diffractive optical element 20 .

[0123] In some embodiments, the image generating unit 10 includes a display chip, and the distance between the first diffractive optical element 20 and the display chip is greater than 50 mm and / or less than 400 mm.

[0124] Since the image generating unit 10 further includes a projection lens, the image beam emitted by the display chip is emitted to the first diffractive optical element 20 through the projection lens, and the first diffractive optical element 20 is located outside the image generating unit 10, the distance between the first diffractive optical element 20 and the display chip needs to be greater than the distance between the display chip and the projection lens.

[0125] In some embodiments, the size of the first diffractive optical element 20 is larger than the size of the display chip. In one implementation scenario, the size of the first diffractive optical element 20 is larger than or equal to four times the size of the display chip.

[0126] In some embodiments, the distance between the first diffractive optical element 20 and the second diffractive optical element 30 is greater than 150 mm and / or less than 500 mm.

[0127] In one implementation scenario, the distance between the second diffractive optical element 30 and the human eye may be about 700 mm.

[0128] Figure 21 is a fourth structural schematic diagram of a head-up display device provided in an embodiment of the present application. In some embodiments, in addition to the image generation unit 10, the first diffractive optical element 20 and the second diffractive optical element 30, the head-up display device also includes a reflective element 50. The reflective element 50 is located on the light-emitting side of the image generation unit 10 and is used to reflect the image light beam emitted by the image generation unit 10 to the first diffractive optical element 20.

[0129] Referring to FIG. 21 , since the reflective element 50 reflects the light emitted by the image generating unit 10 toward the first diffractive optical element 20, based on the reflection principle, the image generating unit 10 and the first diffractive optical element 20 are located on the same side of the reflective element 50. The reflective element 50 reflects the image light beam toward the first diffractive optical element 20, thereby realizing spatial multiplexing, which is beneficial for reducing the volume of the head-up display device and achieving miniaturization of the head-up display device.

[0130] In some embodiments, the reflective element 50 is a plane reflector or a curved reflector. In one implementation scenario, the curved reflector can be a convex mirror, a concave mirror, or a free-form mirror.

[0131] In summary, the image beam emitted by the image generation unit 10 is reflected by the reflective element 50, then passes through the first diffractive optical element 20 to form a virtual image. This image is then reflected by the second diffractive optical element 30 and converges into the human eye. The image perceived by the human eye is the target virtual image formed by the reverse extension of the image beam converging in the far field. Reflecting the image beam by the reflective element 50 further reduces the size of the head-up display device.

[0132] An embodiment of the present application provides a vehicle, which includes a cab and any one of the head-up display devices provided in the above embodiments.

[0133] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A head-up display device, used in a vehicle, comprising: An image generating unit, configured to generate an image beam and emit the image beam to a light modulating element; The light modulation element is located on the light-emitting side of the image generation unit, and is used to modulate the image light beam and emit the modulated image light beam to the micro-optical element; The micro-optical element includes multiple areas, the multiple areas include at least a first effective area, the first effective area is used to reflect the image light beam to the human eye; the multiple areas also include a target area, the transmittance of the target area is higher than the transmittance of the first effective area.

2. The head-up display device according to claim 1, wherein: There are multiple first effective areas, which are arranged periodically.

3. The head-up display device according to claim 2, wherein: The micro-optical element includes a plurality of first effective areas arranged in an array along a first direction and a second direction, wherein the first direction is perpendicular to the second direction.

4. The head-up display device according to claim 1, wherein: The shape of the first effective area is at least one of a circle, a rectangle, a triangle, and an irregular polygon.

5. The head-up display device according to any one of claims 1 to 4, wherein: If the light transmittance of the target area is higher than a first preset threshold, which is greater than the light transmittance of the first effective area, the target area is an invalid area for transmitting light.

6. The head-up display device according to claim 5, wherein: A ratio of an area of ​​the first active region of the micro-optical element to an area of ​​the micro-optical element is greater than 30%, or less than 70%.

7. The head-up display device according to claim 5, wherein: The micro-optical element is located on the windshield of the vehicle, and the ratio of the area of ​​the first effective region included in the micro-optical element to the area of ​​the windshield is less than or equal to 30%.

8. The head-up display device according to claim 5, wherein: If the transmittance of the target area is higher than a second preset threshold, which is greater than the transmittance of the first effective area and less than the first preset threshold, the target area is a second effective area for reflecting the image beam to the human eye.

9. The head-up display device according to claim 8, wherein: A ratio of the sum of the areas of the first active region and the second active region to the area of ​​the micro-optical element is 100%.

10. The head-up display device according to claim 1, wherein: The micro-optical element is a holographic film or an element with a microstructure.

11. A head-up display device, used in a vehicle, comprising: An image generating unit, configured to generate and emit an image beam; a first diffractive optical element, located at a light-emitting side of the image generating unit, for diffracting the image beam and emitting the diffracted image beam to a second diffractive optical element; The second diffractive optical element is used to reflect the image light beam emitted by the first diffractive optical element to the eye box area to form a target virtual image.

12. The head-up display device according to claim 11, wherein: The size of the second diffractive optical element is larger than that of the first diffractive optical element.

13. The head-up display device according to claim 11, wherein: The image generating unit includes a display chip, and the distance between the first diffractive optical element and the display chip is greater than 50 mm and / or less than 400 mm.

14. The head-up display device according to claim 13, wherein: The size of the first diffractive optical element is larger than that of the display chip.

15. The head-up display device according to claim 11, wherein: The target light emitted by the first diffractive optical element has an increased angle in the first direction greater than 8° and / or less than 20°, and an increased angle in the second direction greater than 2° and / or less than 8°, and the first direction and the second direction are perpendicular; The target light is a marginal light whose energy is reduced to 50% of the highest energy in the image light beam emitted by the first diffractive optical element.

16. The head-up display device according to claim 11, wherein: The distance between the first diffractive optical element and the second diffractive optical element is greater than 150 mm and / or less than 500 mm.

17. The head-up display device according to claim 11, wherein: The second diffractive optical element is located in the interlayer of the windshield of the vehicle, or is attached to the windshield.

18. The head-up display device according to any one of claims 11 to 17, wherein: The first diffractive optical element and the second diffractive optical element are holographic films, or elements with microstructures.

19. The head-up display device according to claim 11, wherein: The head-up display device further includes a reflective element, which is located on a light-emitting side of the image generating unit and is configured to reflect the image light beam emitted by the image generating unit to the first diffractive optical element.

20. The head-up display device according to claim 19, wherein: The reflective element is a plane reflector or a curved reflector.

Images