Head-up display system

Abstract

A head-up display system (10), comprising: a projector (12) designed to project an image (14); a primary reflector (16); and an exit pupil replicator (20), wherein the primary reflector (16) is configured to reflect an image (14) projected by the projector (12) to the exit pupil replicator (20), and wherein the exit pupil replicator (20) is configured to divide the projected image (14) into a two-dimensional array of identical projected images (14') with the same intensity; wherein the exit pupil replicator (20) comprises several lateral reflecting surfaces (32A, 32B, 32C, 32D) and several vertical reflecting surfaces (34A, 34B, 34C, 34D), wherein the several lateral reflecting surfaces (32A, 32B, 32C, 32D) are configured to divide the projected image (14) reflected by the primary reflector (16) into a one-dimensional array of identical projected images (14) of equal intensity and to reflect the one-dimensional array of identical projected images (14) of equal intensity to the several vertical reflecting surfaces (34A, 34B, 34C, 34D); wherein the multiple vertical reflective surfaces (34A, 34B, 34C, 34D) are designed to divide the one-dimensional array of identical projected images (14) of equal intensity, which are reflected from the multiple lateral reflective surfaces (32A, 32B, 32C, 32D), into the two-dimensional array of identical projected images (14) of equal intensity and to reflect the two-dimensional array of identical projected images (14) of equal intensity upwards to a windshield (26); wherein each of the several lateral reflecting surfaces (32A, 32B, 32C, 32D) and each of the several vertical reflecting surfaces (34A, 34B, 34C, 34D) is a composite prism (72).

Description

Technical field

[0001] The present description refers to a head-up display system for the driver of a vehicle, for example, a car. introduction

[0002] Head-up displays (HUDs) have become commonplace in modern automobiles. HUDs project useful information such as speed and navigation data into the driver's field of vision. This eliminates the need for the driver to look down at the dashboard displays, allowing them to keep their eyes on the road and reducing distractions.

[0003] New HUD systems can project augmented reality images, such as optimal driving routes or navigation arrows, to provide images that appear to be on the actual road surface. Unfortunately, HUD systems with this capability are calibrated to provide precise placement for the "nominal driver." To ensure the driver sees the projected images in the correct position on the road, the position of the projected image must be adjusted to account for varying vehicle heights and the driver's varying vertical eye positions relative to the HUD system.

[0004] To increase the number of drivers who can see the head-up display images, such systems often use an exit pupil enlarger / replicator or a waveguide to expand the field of view. The image is projected into the exit pupil replicator and then spreads within it, being extracted multiple times. This repeated transmission of light within the exit pupil replicator dilates the pupil, allowing the viewer to see the image from an expanded field of view. In addition to expanding the field of view, the exit pupil replicator also enlarges the original projected image coming from the projector.

[0005] Conventional exit pupil replicators contribute most to the overall size and mass of HUD systems.

[0006] WO 2019 / 238 885 A1 describes an optical waveguide for a display device and methods for manufacturing such an optical waveguide. The optical waveguide has a substrate on which a hologram layer is applied. A cover layer, consisting of a translucent material that has undergone a curing process, is applied to the hologram layer. The substrate can be made of glass. Alternatively, the substrate can also consist of a translucent material that has undergone a curing process.

[0007] EP 4 300 161 A1 describes a head-up display system with a display that emits a luminous flux, which is visually perceived by a viewer as a virtual image, and a light guide body that directs the luminous flux to the light-transmitting element. The light guide body comprises an incident surface onto which the luminous flux from the display strikes, and an emissive surface from which the luminous flux is emitted from the light guide body. A light ray in the center of the luminous flux emitted by the display strikes the light guide body at an angle to the normal direction of the incident surface.The luminous flux incident on the optical fiber's surface is modified in one direction of propagation. The luminous flux is replicated into a multitude of luminous fluxes in a horizontal direction of the virtual image perceived by the viewer. These replicated luminous fluxes are then further replicated in a vertical direction of the virtual image to be emitted from the emission surface, thus extending the visual perception area. A light ray in the center of the light fluxes emitted by the optical fiber is emitted towards the transparent element while being inclined with respect to the normal direction of the emission surface of the optical fiber.

[0008] While current HUD systems and methods fulfill their purpose, the object of the invention is to provide a new and improved head-up display system that includes an exit pupil replicator and reduces the overall size and mass of the head-up display system. Description

[0009] The invention is defined by the claims.

[0010] According to the invention, a head-up display system comprises a projector configured to project an image, a primary reflector, and an exit pupil replicator, wherein the primary reflector reflects an image projected by the projector onto the exit pupil replicator, and the exit pupil replicator divides the projected image into a two-dimensional array of identical projected images of equal intensity. The exit pupil replicator comprises multiple lateral reflective surfaces and multiple vertical reflective surfaces, wherein the multiple lateral reflective surfaces are configured to divide the projected image reflected by the primary reflector into a one-dimensional array of identical projected images of equal intensity and to reflect the one-dimensional array of identical projected images of equal intensity onto multiple vertical reflective surfaces.The multiple vertical reflective surfaces are designed to split the one-dimensional array of identical projected images of equal intensity, reflected by the multiple lateral reflective surfaces, into a two-dimensional array of identical projected images of equal intensity, and to reflect this two-dimensional array of identical projected images of equal intensity upwards towards a windshield. Each of the multiple lateral reflective surfaces and each of the multiple vertical reflective surfaces is a composite prism.

[0011] According to one embodiment, the projected image is projected from the projector onto the primary reflector, reflected from the primary reflector onto the multiple lateral reflective surfaces of the exit pupil replicator, and reflected from the multiple lateral reflective surfaces of the exit pupil replicator onto the multiple vertical reflective surfaces of the exit pupil replicator in a single plane.

[0012] According to one embodiment, the projected image is projected from the projector onto the primary reflector and reflected from the primary reflector onto the multiple lateral reflective surfaces of the exit pupil replicator in a first plane, and the projected image is reflected from the multiple lateral reflective surfaces of the exit pupil replicator onto the multiple vertical reflective surfaces of the exit pupil replicator in a second plane.

[0013] According to one embodiment, each prism comprises a first part and a second part, wherein a refractive index of the second part is higher than a refractive index of the first part, wherein a portion of an image incident on the prism is reflected from an outer surface of the first part, and a portion of the image incident on the prism passes through the first part and the second part and exits the second part parallel to a path of the image incident on the prism.

[0014] According to one embodiment, each of the multiple lateral reflective surfaces and each of the multiple vertical reflective surfaces is a flat beam splitter.

[0015] According to one embodiment, each of the multiple lateral reflective surfaces and each of the multiple vertical reflective surfaces is a prism and / or a flat beam splitter.

[0016] According to one embodiment, the multiple lateral reflective surfaces are arranged in series and have different reflectivity, each of the multiple lateral reflective surfaces being configured to reflect a portion of an image reflected from the primary reflector to the multiple vertical reflective surfaces and to transfer a portion of the image reflected from the primary reflector to an adjacent one of the multiple lateral reflective surfaces, with a last of the multiple lateral reflective surfaces being configured to reflect 100% of the image reflected from the primary reflector to the multiple vertical reflective surfaces.

[0017] According to one embodiment, the multiple vertical reflective surfaces are arranged in series and have different reflectivities, each of the multiple vertical reflective surfaces being configured to reflect a portion of an image reflected by each of the multiple lateral reflective surfaces upwards to the windshield and to transfer a portion of the image reflected by each of the multiple lateral reflective surfaces to an adjacent of the multiple vertical reflective surfaces, with a last of the multiple vertical reflective surfaces being configured to reflect 100% of the image reflected by each of the multiple lateral reflective surfaces upwards to the windshield.

[0018] Further areas of application will become apparent from this description. It should be understood that the description and specific examples serve only as illustrations and are not intended to limit the scope of this description. Brief description of the drawings

[0019] The drawings described here are for illustrative purposes only and are not intended to limit the scope of the present description in any way. Fig. Figure 1 is a perspective view of a head-up display system according to an exemplary embodiment; Fig. Figure 2 is a perspective schematic view of an exit pupil replicator according to an exemplary embodiment, in which each of the multiple lateral reflective surfaces and each of the multiple vertical reflective surfaces comprises a composite prism; Fig. Figure 3 is a perspective schematic view of an exit pupil replicator according to an exemplary embodiment, in which a projector and a primary reflector lie in a first plane and several lateral reflective surfaces and the several vertical reflective surfaces lie in a second plane; Fig. 4 is a top view of the in Fig. 2 shown exit pupil replicator; Fig. 5 is a side view of the in Fig. 2 shown exit pupil replicator; Fig. Figure 6 is a perspective schematic view of an exit pupil replicator according to an exemplary embodiment, wherein each of the multiple lateral reflective surfaces and each of the multiple vertical reflective surfaces comprises a flat beam splitter; Fig. 7 is a top view of the in Fig. 6 shown exit pupil replicator; and Fig. Figure 8 is a side section view of a composite prism according to an exemplary embodiment of the present description.

[0020] The illustrations are not necessarily to scale, and some features may be exaggerated or reduced in size, for example, to show details of certain components. In some cases, known components, systems, materials, or methods have not been described in detail so as not to obscure the present description. Therefore, specific structural and functional details shown here are not to be understood as limiting, but merely as a basis for the claims and as a representative basis to show a person skilled in the art how to apply the present description in various ways. Detailed description

[0021] The following description is merely exemplary and is not intended to limit the present presentation, application, or use. Furthermore, there is no intention to be bound by any express or implied theory set forth in the preceding technical section, background, summary, or subsequent detailed description. It should be understood that in the drawings, corresponding reference numerals point to identical or corresponding parts and features.

[0022] The term "vehicle" as used here is not limited to motor vehicles. While the technology presented here is primarily described in the context of motor vehicles, it is not restricted to them. The concepts can be used in a wide variety of applications, for example, in conjunction with aircraft, watercraft, other vehicles, and consumer electronic components.

[0023] Referring to Fig. 1 and Fig. 2 comprises a head-up display (HUD) system 10 according to the present description and a projector 12 configured to project an image 14. In an exemplary embodiment, the projector 12 can be a hologram projector 12 comprising a red laser, a green laser, a blue laser, and corresponding spatial light modulators for each laser. Each of the red, green, and blue lasers projects through the associated spatial light modulators and is collimated to form a holographic image 14, which is projected outwards.

[0024] A primary reflector 16 is located near the projector 12 and is configured to reflect the image 14 projected by the projector 12, as indicated by arrow 18, to an exit pupil replicator 20, as indicated by arrow 22. In an exemplary embodiment, the primary reflector 16 can be a beam control device. A beam control device is used to adjust the look-down angle (LDA) of the image 14 projected by the projector 12. In optical systems, beam control can be achieved by changing the refractive index of the medium through which the beam is transmitted or by using mirrors, prisms, lenses, or rotating diffraction gratings. Examples of optical beam control include mechanical gimbal suspensions based on mirrors, galvanometer mechanisms that rotate mirrors, Risley prisms, phased-array optics, and microelectromechanical systems (MEMS) with micromirrors.

[0025] The exit pupil replicator 20 is designed to split the projected image 14 into a two-dimensional array of identical projected images 14' of equal intensity. The array of identical projected images 14' is directed upwards onto an inner surface 24 of a windshield 26 and is reflected from the inner surface 24 of the windshield 26 onto the field of view 28. The field of view 28 is the three-dimensional area in which the driver of the vehicle can see the entire projected image of the HUD system. An eye ellipse 30 is a three-dimensional graphical representation of a multivariate normal distribution used to approximate the distribution of the driver's eye positions within the vehicle. The eye ellipse 30 is represented by two three-dimensional ellipses, one for the right eye and one for the left eye.

[0026] By dividing the projected image 14 into a two-dimensional array 14' of identical projected images of equal intensity, the exit pupil replicator 20 creates a multitude of coplanar partial fields of view, one for each of the identical projected images, thereby increasing the effective field of view 28 within which the driver can see the HUD image.

[0027] The exit pupil replicator 20 comprises several lateral reflecting surfaces 32A, 32B, 32C, 32D and several vertical reflecting surfaces 34A, 34B, 34C, 34D. As shown, the exit pupil replicator 20 comprises four lateral reflecting surfaces 32A, 32B, 32C, 32D and four vertical reflecting surfaces 34A, 34B, 34C, 34D. It is self-evident that the new features of the present description are applicable to an exit pupil replicator 20 with any number of suitable lateral reflecting surfaces 32A, 32B, 32C, 32D and vertical reflecting surfaces 34A, 34B, 34C, 34D. The multiple lateral reflective surfaces 32A, 32B, 32C, 32D are designed such that they divide the projected image 14 reflected by the primary reflector 16 into a one-dimensional array of identical projected images with the same intensity. As in Fig. As shown in Figure 2, the four lateral reflective surfaces 32A, 32B, 32C, 32D divide the image reflected from the primary reflector into a 1×4 array of identical projected images of equal intensity and reflect the one-dimensional array of identical projected images of equal intensity to the multiple vertical reflective surfaces, as shown by arrows 36.

[0028] Referring to Fig. 2 In an exemplary embodiment, the projector 12, the primary reflector 16 and the exit pupil replicator 20 are arranged such that the projected image 14 is projected from the projector 12 onto the primary reflector 16, as shown by arrow 18, reflected from the primary reflector 16 onto the multiple lateral reflective surfaces 32A, 32B, 32C, 32D of the exit pupil replicator 20, as shown by arrow 22, and reflected from the multiple lateral reflective surfaces 32A, 32B, 32C, 32D of the exit pupil replicator 20 to the multiple vertical reflective surfaces 34A, 34B, 34C, 34D of the exit pupil replicator 20, as shown by arrow 36, within a single plane.As shown, the projected image 14 is projected from the projector 12 onto the primary reflector 16, reflected from the primary reflector 16 onto the multiple lateral reflective surfaces 32A, 32B, 32C, 32D of the exit pupil replicator 20, and reflected from the multiple lateral reflective surfaces 32A, 32B, 32C, 32D of the exit pupil replicator 20 to the multiple vertical reflective surfaces 34A, 34B, 34C, 34D of the exit pupil replicator 20 within a plane defined by the x-axis 38 and the y-axis 40.

[0029] Referring to Fig. In another exemplary embodiment, the projector 12, the primary reflector 16 and the exit pupil replicator 20 are positioned such that the projected image 14 is projected from the projector 12 onto the primary reflector 16 and reflected from the primary reflector 16 onto the multiple lateral reflective surfaces 32A, 32B, 32C, 32D of the exit pupil replicator 20 within a first plane defined by the x-axis 38 and a z-axis 42. The projected image 14 is reflected by the multiple lateral reflection surfaces 32A, 32B, 32C, 32D of the exit pupil replicator 20 to the multiple vertical reflection surfaces 34A, 34B, 34C, 34D of the exit pupil replicator 20 in a second plane defined by the x-axis 38 and the y-axis 40.

[0030] Fig. Figure 4 shows a top view of the exit pupil replicator 20, illustrating how the multiple lateral reflecting surfaces 32A, 32B, 32C, 32D divide the image and reflect it onto the multiple vertical reflecting surfaces 34A, 34B, 34C, 34D. The multiple lateral reflecting surfaces 32A, 32B, 32C, 32D are arranged in series and have different reflectivities. Each of the multiple lateral reflective surfaces 32A, 32B, 32C, 32D is designed to reflect a portion of an image reflected from the primary reflector 16 onto the multiple vertical reflective surfaces 34A, 34B, 34C, 34D and to transfer a portion of the image reflected from the primary reflector 16 onto an adjacent one of the multiple lateral reflective surfaces 32A, 32B, 32C, 32D.As shown, the majority of the lateral reflection surfaces 32A, 32B, 32C, 32D comprise a first lateral reflection surface 32A, a second lateral reflection surface 32B, a third lateral reflection surface 32C and a fourth lateral reflection surface 32D.

[0031] Each of the first, second, third, and fourth lateral reflective surfaces 32A, 32B, 32C, 32D has a different reflectance. When the projected image strikes the first lateral reflective surface 32A, a portion of the projected image is reflected by the multiple vertical reflective surfaces 34A, 34B, 34C, 34D, as indicated by arrow 44, and a portion of the projected image passes through the first lateral reflective surface 32A to the adjacent second lateral reflective surface 32B, as indicated by arrow 46. When the projected image hits the second lateral reflective surface 32B, a portion of the projected image is reflected at the multiple vertical reflective surfaces 34A, 34B, 34C, 34D, as shown by arrow 48, and a portion of the projected image passes through the second lateral reflective surface 32B to the adjacent third reflective surface 32C, as shown by arrow 50.When the projected image strikes the third lateral reflecting surface, a portion of the projected image is reflected by the multiple vertical reflecting surfaces 34A, 34B, 34C, 34D, as shown by arrow 52, ​​and a portion of the projected image passes through the third lateral reflecting surface 32C to the adjacent fourth lateral reflecting surface 32D, as shown by arrow 54. The fourth lateral reflecting surface 32D is the last in the series of multiple lateral reflecting surfaces 32A, 32B, 32C, 32D. The reflectance of the fourth lateral reflecting surface 32D is 100%, so the image is reflected by the multiple vertical reflecting surfaces 34A, 34B, 34C, 34D, as shown by arrow 56.

[0032] The image reflected from each of the first, second, third, and fourth lateral reflecting surfaces 32A, 32B, 32C, 32D to the multiple vertical reflecting surfaces 34A, 34B, 34C, 34D must have the same intensity; that is, the reflectance of the first lateral reflecting surface 32A is lower than the reflectance of the second lateral reflecting surface 32B, which is lower than that of the third lateral reflecting surface 32C, which is lower than that of the fourth lateral reflecting surface 32D. The fourth lateral reflecting surface 32D is the last in the series and has a reflectance of 100%. To ensure that the image reflected from each of the multiple lateral reflective surfaces 32A, 32B, 32C, 32D to the multiple vertical reflective surfaces 34A, 34B, 34C, 34D has the same intensity, the reflectance R of the i tenLateral reflection area for an exit pupil replicator 20 with m lateral reflection areas given by: Rith=1m1−i−1m×100%

[0033] The surface reflectance of the multiple lateral reflecting surfaces 32A, 32B, 32C, 32D can be controlled using known techniques, for example, as non-limiting examples, by using a special dielectric layer for each area to achieve a specific reflectance, by sputtering different densities of silver nanowires or metallic nanoparticles, or by using a special surface not adapted to the refractive index (photopolymer with controlled polymerization to create a specific refractive index).

[0034] Fig. Figure 5 shows a side view of the exit pupil replicator 20, illustrating how the multiple vertical reflective surfaces 34A, 34B, 34C, and 34D divide the image and reflect it upwards towards the windshield 26. The multiple vertical reflective surfaces 34A, 34B, 34C, and 34D are arranged in series and have different reflectivities. Each of the multiple vertical reflective surfaces 34A, 34B, 34C, 34D is designed to reflect a portion of the image reflected by each of the multiple lateral reflective surfaces 32A, 32B, 32C, 32D upwards to the windshield 26 and to transmit a portion of the image reflected by each of the multiple lateral reflective surfaces 32A, 32B, 32C, 32D to an adjacent one of the multiple vertical reflective surfaces 34A, 34B, 34C, 34D.As shown, the majority of the vertical reflective surfaces 34A, 34B, 34C, 34D comprise a first vertical reflective surface 34A, a second vertical reflective surface 34B, a third vertical reflective surface 34C, and a fourth vertical reflective surface 34D. Thus, the multiple vertical reflective surfaces 34A, 34B, 34C, 34D are configured to split each of the four identical images within the 1x4 array of images reflected by the four lateral reflective surfaces 32A, 32B, 32C, 32D, and to divide the image from each of the four lateral reflective surfaces 32A, 32B, 32C, 32D into four identical images, thereby creating a two-dimensional 4x4 array of identical images of equal intensity, which is reflected upwards to the inner surface 24 of the windshield 26.

[0035] Each of the first, second, third, and fourth vertical reflective surfaces 34A, 34B, 34C, 34D has a different reflectance. When projected images from each of the first, second, third, and fourth lateral reflective surfaces 32A, 32B, 32C, 32D strike the first vertical reflective surface 34A, as indicated by arrow 58, a portion of each image from each of the first, second, third, and fourth lateral reflective surfaces 32A, 32B, 32C, 32D is reflected upwards to the windscreen 26, as indicated by arrow 60, and a portion of each image from each of the first, second, third, and fourth lateral reflective surfaces 32A, 32B, 32C, 32D passes through the first vertical reflective surface 34A to the adjacent second vertical reflective surface 34B, as indicated by arrow 62.When the images from each of the first, second, third and fourth lateral reflective surfaces 32A, 32B, 32C, 32D meet the second vertical reflective surface 34B, a proportion of each of the images from each of the first, second, third and fourth lateral reflective surfaces 32A, 32B, 32C, 32D is reflected upwards to the windscreen 26, as indicated by arrow 64, and a proportion of each of the images from each of the first, second, third and fourth lateral reflective surfaces 32A, 32B, 32C, 32D passes through the second vertical reflective surface 34B to the adjacent third vertical reflective surface 34C, as indicated by arrow 66.When each of the images from each of the first, second, third, and fourth lateral reflective surfaces 32A, 32B, 32C, 32D strikes the third vertical reflective surface 34C, a portion of each of the images from each of the first, second, third, and fourth lateral reflective surfaces 32A, 32B, 32C, 32D is reflected upwards to the windshield 26, as indicated by arrow 68, and a portion of each of the images from each of the first, second, third, and fourth lateral reflective surfaces 32A, 32B, 32C, 32D passes through the third vertical reflective surface 34C to the adjacent fourth vertical reflective surface 34D, as indicated by arrow 70. The fourth vertical reflective surface 34D is the last in the series of multiple vertical reflective surfaces 34A, 34B, 34C, 34D. The reflectance of the fourth lateral reflective surface 32D is 100%, so that the image is reflected upwards towards the windshield 26, as indicated by arrow 72.

[0036] The images reflected upwards from the first, second, third, and fourth vertical reflective surfaces 34A, 34B, 34C, 34D towards the windshield 26 must have the same intensity; that is, the reflectance of the first vertical reflective surface 34A is lower than that of the second vertical reflective surface 34B, which is lower than that of the third vertical reflective surface 34C, which is lower than that of the fourth vertical reflective surface 34D. The fourth vertical reflective surface 34D is the last in the series and has a reflectance of 100%. To ensure that the image reflected upwards from each of the multiple vertical reflective surfaces 34A, 34B, 34C, 34D towards the windshield has the same intensity, the reflectance R of each surface is determined by the following formula: ten vertical reflection area for an exit pupil replicator 20 with n lateral reflection areas given by: Rith=1n1−i−1n×100%

[0037] With reference to Fig. 2, Fig. 3, Fig. 4 and Fig. In an exemplary embodiment, each of the multiple lateral reflective surfaces 32A, 32B, 32C, 32D and each of the multiple vertical reflective surfaces 34A, 34B, 34C, 34D is a composite prism 72. The prism 72 can be of any type suitable for achieving the reflection and transmission properties described herein. As shown in Fig. As shown in Figure 8, in an exemplary embodiment each prism 72 comprises a first part 74 and a second part 76. Each of the first and second parts of the prism 72 has a refractive index, wherein the refractive index of the second part 76 is higher than the refractive index of the first part 74.

[0038] As shown, the first part 74 of the compound prism 72 has the shape of a triangle with a base 78 parallel to the direction of motion of an incoming image, as indicated by the arrow 80, and an outer face 82 oriented at an angle of 45 degrees to the base 78. The second part 76 of the compound prism 72 has the shape of a right-angled triangle. The angles θ1, θ out and θ in are determined on the basis of the refractive index of the first and second parts 74, 76. Where n air the refractive index of air, n1 is the refractive index of the first part 74 and n2 is the refractive index of the second part 76: nair∗sin45 degrees=n1∗sinθt, n2∗sinθin=nair∗sinθout, and θin=θout+θt−45 degrees.

[0039] If the refractive index of the second part is 76, n2, larger, the angle θ insmaller, which reduces the overall size of the prism and allows for a thinner design.

[0040] When an image strikes the composite prism 72, as indicated by arrow 80, a portion of the image striking the composite prism 72 is reflected by the outer surface 82 of the first part 74, as shown by arrow 84, and a portion of the image striking the composite prism 72 passes through the first part 74 and the second part 76, as shown by arrow 86, and exits the second part 76 parallel to the path of the image striking the outer surface of the first part 74 of the prism 72, as shown by arrow 88. The image path shown by arrow 80 is parallel to the image path shown by arrow 88.

[0041] With reference to Fig. 6 and Fig.7, in another exemplary embodiment, an exit pupil replicator 120 comprises several lateral reflecting surfaces 132A, 132B, 132C, 132D and several vertical reflecting surfaces 134A, 134B, 134C, 134D, wherein each of the several lateral reflecting surfaces 132A, 132B, 132C, 132D and each of the several vertical reflecting surfaces 134A, 134B, 134C, 134D and the primary reflector 116 is a flat beam splitter, such as a pellic beam splitter configured is to offer reflection and transmission properties similar to those of a composite prism.In various embodiments, an exit pupil replicator 20, 120 of the present description can, depending on the specific design parameters, comprise combinations of lateral and vertical reflective surfaces 32A, 32B, 32C, 32D, 132A, 132B, 132C, 132D, 34A, 34B, 34C, 34D, 134A, 134B, 134C, 134D, which include both composite prisms 72 and beam splitters.

[0042] A head-up display system of the present description offers a significant opportunity to reduce the overall weight and mass of the head-up system by using an exit pupil replicator comprising multiple lateral reflective surfaces and multiple vertical reflective surfaces to transmit a two-dimensional array of identical images of equal intensity upwards to an inner surface of the windscreen, thereby creating a larger overall field of vision for the driver.

Claims

[1] A head-up display system (10), comprising: a projector (12) designed to project an image (14); a primary reflector (16); and an exit pupil replicator (20), wherein the primary reflector (16) is configured to reflect an image (14) projected by the projector (12) to the exit pupil replicator (20), and wherein the exit pupil replicator (20) is configured to divide the projected image (14) into a two-dimensional array of identical projected images (14') with the same intensity; wherein the exit pupil replicator (20) comprises several lateral reflecting surfaces (32A, 32B, 32C, 32D) and several vertical reflecting surfaces (34A, 34B, 34C, 34D), wherein the several lateral reflecting surfaces (32A, 32B, 32C, 32D) are configured to divide the projected image (14) reflected by the primary reflector (16) into a one-dimensional array of identical projected images (14) of equal intensity and to reflect the one-dimensional array of identical projected images (14) of equal intensity to the several vertical reflecting surfaces (34A, 34B, 34C, 34D); wherein the multiple vertical reflective surfaces (34A, 34B, 34C, 34D) are designed to divide the one-dimensional array of identical projected images (14) of equal intensity, which are reflected from the multiple lateral reflective surfaces (32A, 32B, 32C, 32D), into the two-dimensional array of identical projected images (14) of equal intensity and to reflect the two-dimensional array of identical projected images (14) of equal intensity upwards to a windshield (26); wherein each of the several lateral reflecting surfaces (32A, 32B, 32C, 32D) and each of the several vertical reflecting surfaces (34A, 34B, 34C, 34D) is a composite prism (72). [2] Head-up display system (10) according to claim 1, wherein the projected image (14) is projected from the projector (12) onto the primary reflector (16), is reflected from the primary reflector (16) onto the multiple lateral reflective surfaces (32A, 32B, 32C, 32D) of the exit pupil replicator (20) and is reflected from the multiple lateral reflective surfaces (32A, 32B, 32C, 32D) of the exit pupil replicator (20) onto the multiple vertical reflective surfaces (34A, 34B, 34C, 34D) of the exit pupil replicator (20) in a single plane. [3] Head-up display system (10) according to claim 1, wherein the projected image (14) is projected by the projector (12) onto the primary reflector (16) and is reflected by the primary reflector (16) to the multiple lateral reflective surfaces (32A, 32B, 32C, 32D) of the exit pupil replicator (20) in a first plane, and the projected image (14) is reflected by the multiple lateral reflective surfaces (32A, 32B, 32C, 32D) of the exit pupil replicator (20) to the multiple vertical reflective surfaces (34A, 34B, 34C, 34D) of the exit pupil replicator (20) in a second plane. [4] Head-up display system (10) according to claim 1, wherein each prism (72) comprises a first part (74) and a second part (76), wherein a refractive index of the second part (76) is higher than a refractive index of the first part (74), wherein a portion of an image (14) incident on the prism (72) is reflected from an outer surface (82) of the first part (74) and a portion of the image (14) incident on the prism (72) passes through the first part (74) and the second part (76) and exits the second part (76) parallel to a path of the image (14) incident on the prism (72). [5] Head-up display system (10) according to claim 1, wherein the multiple lateral reflective surfaces (32A, 32B, 32C, 32D) are arranged in series and have different reflectivities, wherein each of the multiple lateral reflective surfaces (32A, 32B, 32C, 32D) is configured to reflect a portion of an image (14) reflected from the primary reflector (16) to the multiple vertical reflective surfaces (34A, 34B, 34C, 34D) and to transmit a portion of the image (14) reflected from the primary reflector (16) to an adjacent one of the multiple lateral reflective surfaces (32A, 32B, 32C, 32D), wherein a final reflective surface (32D) of the multiple lateral reflective surfaces (32A, 32B, 32C, 32D) is configured to to reflect 100% of the image (14) reflected by the primary reflector (16) to the multiple vertical reflection surfaces (34A, 34B, 34C, 34D).

Images