HOLOGRAPHIC DISPLAY SYSTEM FOR A MOTOR VEHICLE AND MOTOR VEHICLE

Abstract

A holographic display system (100) for a motor vehicle (106), wherein the holographic display system comprises the following: a coherent light source (124) for generating a coherent beam of light; a spatial light modulator, SLM (102), with a two-dimensional pixel arrangement (104) for modulating a phase of the coherent light and for generating a first diffracted ray (128) associated with a principal image and a second diffracted ray (130) associated with a conjugate image, wherein the first and second diffracted rays (128, 130) are spaced apart by a first angle (α); an optical component (132) for transmitting at least one of the first and second diffracted rays (128, 130) and for angularly separating the first and second diffracted rays (128, 130) from each other by a second angle (θ) which is larger than the first angle (α), wherein the optical component (132) comprises a diffraction grating (134) or a refracting prism for diffracting at least one of the first and second diffracted rays (128, 130); a display surface (122) arranged relative to the optical component (132) to receive the first diffracted ray (128) from the optical component (132) and to display the main image, wherein the display surface (122) is free of the second diffracted ray (130); and a computer (136), comprising: a processor (138) connected to the coherent light source (124) and the SLM (102); and a memory (140) containing instructions such that the processor (138) is programmed to control the two-dimensional pixel arrangement (104) of the SLM (102) that generates the first and second diffracted beams (128, 130).

Description

[0001] The present disclosure relates to holographic display systems for motor vehicles and in particular to a holographic display system which angularly separates a main image from a conjugate image in order to display only the main image on a display surface and to improve the overall image quality.

[0002] Automakers are continuously exploring improvements to augmented reality (AR) head-up displays (HUDs) using spatial light modulators (SLMs). In an AR HUD where the SLM's phase modulation capability is not 2π, a conjugate image appears in the same field of view as the primary image, degrading image quality. Modern luxury or premium vehicles may incorporate AR HUDs with spatial light modulators (SLMs) that eliminate conjugate images by fine-tuning the SLMs for red, green, and blue and applying 2π phase modulation to each color. However, compared to SLMs not modified for 2π phase modulation, the SLM modulating a red laser requires a thicker cell spacing or liquid crystal with higher birefringence, resulting in a longer response time.

[0003] US patent 2018 / 0314065A1 discloses a head-up display device and a head-up display method.The head-up display device comprises: a light source configured to generate a modulating light beam; a spatial phase light modulator configured to modulate a phase of the modulating light beam and emit at least two phase-modulated light beams; a reproduction component configured to perform image reproduction on the at least two phase-modulated light beams to produce at least two reproduced images; at least two diffusers configured to receive and scatter the at least two reproduced images generated by the reproduction component; and a reflector arrangement configured to direct the at least two light beams scattered by the at least two diffusers to a projection area to produce at least two projected images at different spatial positions.

[0004] US 2019 / 0041797A1 discloses a holographic projector comprising a spatial light modulator, a light receiving element, and a driver. The spatial light modulator is arranged to receive and display a computer-generated hologram and spatially modulates incident light to form a holographic reconstruction in accordance with the computer-generated hologram. The light receiving element is arranged to receive spatially modulated light along an optical axis from the spatial light modulator, and the holographic reconstruction is formed on the light receiving element. The driver is coupled to the light receiving element to move it in a plane. The driver is configured to move the light receiving element while maintaining an orientation of the light receiving element relative to the spatial light modulator that is substantially constant.

[0005] While existing holographic display systems fulfill their purpose, there is a need for a new and improved holographic display system that addresses these problems.

[0006] According to several aspects of the present disclosure, a holographic display system for a motor vehicle is provided. The system comprises a coherent light source for generating a coherent light beam. The system further comprises a spatial light modulator (SLM) with a two-dimensional pixel array. The two-dimensional pixel array is encoded with holograms to modulate a phase of the coherent light and to generate a first diffracted beam, associated with a principal image, and a second diffracted beam, associated with a conjugate image, wherein the first and second diffracted beams are angularly separated from each other by a first angle. The system further comprises an optical component for transmitting the first and / or the second diffracted beam, wherein the first and second diffracted beams are angularly separated from each other by a second angle greater than the first angle.The optical component comprises a diffraction grating or a refracting prism for diffracting at least one of the first and second diffracted rays. The system further comprises a display surface arranged relative to the optical component to receive the first diffracted ray from the optical component and to display the principal image, the display surface being free of the second diffracted ray. The system further comprises a computer with a processor connected to the coherent light source and the SLM. The computer further comprises memory containing instructions such that the processor is programmed to control the two-dimensional pixel array of the SLM to generate the first and second diffracted rays.

[0007] In one aspect, the SLM is able to generate a phase shift in a range between 0 and 2π, although an actual range of the phase shift is not equal to 2π.

[0008] Another aspect is that the coherent light source is a laser.

[0009] In another aspect, SLM is a liquid crystal on silicon (LCoS) SLM.

[0010] According to several aspects of the present disclosure, a motor vehicle comprises a body that defines a passenger compartment. The motor vehicle further comprises a plurality of reflective surfaces surrounding the passenger compartment, wherein the reflective surfaces include at least one mirror, a front windshield, a rear windshield, a sunroof, and a plurality of side windows surrounding the passenger compartment. The motor vehicle further comprises a holographic display system (System) connected to the body. The System comprises a coherent light source for generating a coherent light beam. The System further comprises a spatial light modulator (SLM) with a two-dimensional pixel array.The two-dimensional pixel array is encoded with holograms to modulate a phase of coherent light and generate a first diffracted ray, corresponding to a principal image, and a second diffracted ray, corresponding to a conjugate image, wherein the first and second diffracted rays are spaced apart by a first angle. The system further comprises an optical component for transmitting at least one of the first and second diffracted rays and for angularly spacing the first and second diffracted rays apart by a second angle, the second angle being greater than the first angle. The optical component includes a diffraction grating or a refracting prism for diffracting at least one of the first and second diffracted rays.The system further comprises a display surface arranged relative to the optical component to receive the first diffracted ray from the optical component and display the primary image, with the display surface being free of the second diffracted ray. The system further comprises a computer with a processor connected to the coherent light source and the SLM. The computer also has memory containing instructions such that the processor is programmed to control the two-dimensional pixel array of the SLM to generate the first and second diffracted rays.

[0011] In one case, the display area is part of the mirror, the front windscreen, the rear windscreen, the sunroof, or the side windows.

[0012] In another aspect, the system also includes a combination glass unit located in the passenger cabin, and the display area is part of the combination glass unit.

[0013] In another aspect, the SLM is able to generate a phase shift in a range between 0 and 2π, although an actual range of the phase shift is not equal to 2π.

[0014] Another aspect is that the coherent light source is a laser.

[0015] In another aspect, SLM is a liquid crystal on silicon (LCoS) SLM.

[0016] According to several aspects of the present disclosure, a method for operating a holographic display system for a motor vehicle is provided. The system comprises a coherent light source, a spatial light modulator (SLM) with a two-dimensional pixel array, an optical component, a display surface, and a computer with a processor and memory. The method includes the coherent light source generating a beam of coherent light. The method further includes the SLM modulating a phase of the coherent light, generating a first diffracted beam associated with a principal image and a second diffracted beam associated with a conjugate image, the first and second diffracted beams being spaced apart from each other by a first angle.The method further includes the optical component spacing the first and second diffracted beams apart by a second angle, the second angle being larger than the first angle. The method further includes the processor controlling the two-dimensional pixel array of the SLM that generates the first and second diffracted beams.

[0017] In one aspect, the method further includes the fact that the SLM generates a phase shift of the coherent light, where an actual range of the phase shift is not equal to 2π.

[0018] In another aspect, the process also includes a laser that generates the beam of coherent light.

[0019] Another aspect of the process is that a liquid crystal on silicon (LCoS) SLM modulates the phase of the coherent light to generate the first and second diffracted beams.

[0020] In another aspect, the method also includes a diffraction grating that diffracts at least one of the first and second diffracted rays.

[0021] In another aspect, the method includes a refracting prism for refracting at least one of the first and second diffracted rays.

[0022] The figures described here serve only for illustration and are not intended to limit the scope of the present revelation in any way. Fig. Figure 1 is a schematic view of an example of a motor vehicle with a holographic display system. Fig. Figure 2 is a schematic view of a passenger compartment of the motor vehicle of Fig. Figure 1 shows an example of the system with a front window featuring a display area. Fig. Figure 3 is a schematic view of an example of the system of Fig. 2, which shows the system with a diffraction grating for angular separation of the first and second diffraction beams. Fig. Figure 4 is a schematic view of another example of the system of Fig. 2, which shows the system with a refractive prism for angular separation of the first and second diffraction rays. Fig. Figure 5 is a schematic view of a passenger compartment of the motor vehicle of Fig. Figure 1 shows another example of a system with a combination lens with a display area. Fig. Figure 6 is a flowchart of an exemplary procedure for operating the holographic display system of Fig. 1.

[0023] This disclosure describes an example of a motor vehicle with a holographic display system (System) 100 that angularly separates a conjugate image from a principal image to display only the principal image on a display surface. A non-restrictive example of System 100 includes an augmented reality (AR) head-up display (HUD) that can blend holographic display elements with other display elements or environmental features to make holographic images appear relative to the physical world. As detailed in the non-restrictive examples below, System 100 includes a spatial light modulator (SLM) 102 with a two-dimensional pixel array 104.System 100 further comprises a computer for controlling the SLM 102, which displays a primary image and a conjugate image at a specific angle to each other. The system also includes a diffractive or refractive optical component for increasing the angular separation between the primary and conjugate images. The system can be used as part of any land, sea, or air vehicle. In other, non-limiting examples, the system can be used as part of a stationary or mobile power plant, a robot, or a platform. For illustration, an application of the system as an integral part of a motor vehicle is described below, without limiting the present disclosure to such an implementation.

[0024] Referring to Fig. 1 includes an example of a motor vehicle 106, a body 108, which has a passenger compartment 110 ( Fig. 2) and a plurality of reflective surfaces 112 surrounding the passenger compartment 110. The reflective surfaces 112 can include at least a windshield 114, a rear window 116, a sunroof 118, and a plurality of side windows 120 surrounding the passenger compartment 110.

[0025] As in the Fig. 2 and Fig. As best illustrated in Figure 3, the motor vehicle 106 also includes a holographic display system 100 (System) connected to the body 108. The System 100 includes a display area 122. A non-restrictive example of the display area 122 could be an integral part of the front windscreen 114. In other non-restrictive examples, the display area 122 could be part of the rear window 116 ( Fig. 1), the sunroof 118, the side windows 120 or other suitable parts of the vehicle 106.

[0026] Back to Fig. 1: The system 100 further comprises a coherent light source 124 for generating a coherent light beam. A non-restrictive example of the light source 124 could be a laser 126. While in Fig. Figure 1 shows a single LASER 126, but the system can also contain two or more LASERS, such as separate red, green and blue LASERS.

[0027] System 100 further comprises the spatial light modulator (SLM) 102 with the two-dimensional pixel array 104. In this non-restrictive example, the SLM 102 is capable of generating a phase shift in a range between 0 and 2π, although an actual range of the phase shift is not equal to 2π. However, it is considered that other examples of the SLM could be configured to generate a phase shift equal to 2π. The two-dimensional pixel matrix 104 is encoded with holograms to modulate the phase of the coherent light and to generate a first diffracted beam 128, associated with a principal image, and a second diffracted beam 130, associated with a conjugate image, the first and second diffracted beams 128, 130 being spaced apart from each other by a first angle α.The SLM is a fast-switching spatial light modulator (SLM) with high pixel density and a driver circuit that enables a high frame rate. The high frame rate can be 60 Hz, allowing the SLM to display a sequence of partial images sequentially at a speed at which the human eye does not perceive flicker when viewing the entire field of view. However, it is conceivable that the frame rate could be higher or lower than 60 Hz. In a non-restrictive example, the two-dimensional pixel array 104 is a two-dimensional liquid crystal on silicon (LCoS) pixel array 104, which provides diffractive phase elements to support holographic projection. In other examples, the spatial light modulators could be MEMS shutter displays or DLP DMD arrays.The spatial light modulators can be controlled independently to block, transmit, or reflect various beams with high resolution.

[0028] As in Fig. As best illustrated in Figure 3, the system 100 further comprises an optical component 132 for transmitting at least one of the first and second diffracted rays 128, 130 and for angularly separating the first and second diffracted rays 128, 130 from each other by a second angle θ, where the second angle θ is greater than the first angle α. A non-restrictive example of the optical component 132 is a diffraction grating 134 for diffracting at least one of the first and second diffracted rays 128, 130. The diffraction grating 134 transmits and diffractes only the first diffracted ray 128, so that the first diffracted ray 128 is spaced from the second diffracted ray 130 by the second angle θ, and the intrinsic angular separation generated by the SLM 102 is further increased.The diffraction grating 134 can be produced by a holographic process in photopolymer, liquid crystal, reactive monomer or glass formation technology, which causes a periodic refractive index modulation.

[0029] Back to Fig. 1: The system 100 further comprises a computer 136 with a processor 138, which is connected to the light source 124 and the SLM 102. The processor 138 can be used to calculate image data in real time, which is to be output on the two-dimensional pixel array 104 of the SLM 102. The processor 138 can include a processing circuit, which may comprise an application-specific integrated circuit (ASIC), an electronic circuit, and a processor (common, dedicated, or as a group). The computer 136 can further include a memory 140, which executes one or more software or firmware programs, a combinational logic circuit, and / or other suitable components that provide the described functionality. The processor 138 can include an input / output interface 142 for communication with various components, such as an input image source 144 and the SLM 102.When the system 100 is installed in a vehicle, the input image source 144 can be, for example, a vehicle control unit to display measured values, logos, information, entertainment content or other such image-based data.

[0030] The processor 138 can be communicatively connected, e.g., via the vehicle communication module, to more than one local processor, such as electronic control units (ECUs) or similar devices contained in the vehicle 100 for monitoring and / or controlling various vehicle components. The processor 138 is generally configured to communicate with the vehicle communication module via an internal wired and / or wireless network, e.g., a bus or similar within the vehicle 106, such as a Controller Area Network (CAN) or similar, and / or other wired and / or wireless mechanisms. Through the vehicle communication module, the processor 138 can send messages to and / or receive messages from various devices within the vehicle 106, e.g., vehicle sensors, actuators, vehicle components, a human-machine interface (HMI), etc.Alternatively or additionally, in cases where the processor comprises multiple devices, the vehicle communication network can be used for communication between devices, which are represented in this disclosure as Computer 136. Furthermore, as mentioned below, various processors and / or vehicle sensors can supply data to Computer 136. Processor 138 can receive and evaluate data from sensors essentially continuously and / or periodically. Furthermore, object classification or identification procedures can be used, for example, in Processor 138 based on lidar sensor, camera sensor, etc., data to identify lane markings, a type of object (e.g., vehicle, person, rock, pothole, bicycle, motorcycle, etc.), and physical characteristics of objects.

[0031] Memory 140 contains one or more forms of computer-readable media and stores instructions that can be executed by processor 138 to perform various operations, including those disclosed herein. Memory 140 further contains instructions such that processor 138 is programmed to control the two-dimensional pixel array 104 of SLM 102 to modulate the beam of coherent light and generate the first and second diffracted beams 128, 130.

[0032] Another example of a holographic display system 200 is similar to the system 100 from Fig. 3 and has the same components, which are identified by the same numbers increased by 100. However, while the system 100 of Fig. 3 containing the optical component 132 in the form of a diffraction grating 134, the system 200 contains an optical component 232 in the form of a refracting prism that transmits and refracts at least one of the first and second diffracted rays.

[0033] Another example of a holographic display system 300 is similar to the system 100 from Fig. 2 and has the same components, which are characterized by the same numbers increased by 200. However, while the system 100 of Fig. 2 the display area 122 in the form of a surface of the windscreen 114 facing the cabin, the system 300 comprises a combination glass 346 which is separate from the windscreen 314 and arranged inside the passenger cabin 310, and the display area 322 is part of the combination glass 346.

[0034] Referring to Fig. Section 6 provides a method 400 for operating the holographic display system 100 for the motor vehicle 106. The method 400 begins in block 402 with the generation of an initial actuation signal by the processor and the generation of the beam of coded light by the light source 124 in response to the light source 124 receiving the initial actuation signal from the processor 138. In this non-limiting example, the laser 126 generates the beam of coherent light. However, it is conceivable that the system includes two or more lasers, such as separate red, green, and blue lasers.

[0035] In block 404, processor 138 generates a second drive signal to control the two-dimensional pixel array of the SLM 102, which generates the first and second diffracted beams 128, 130, in response to the SLM 102 receiving the second drive signal from processor 138. More precisely, the SLM 102 is a liquid crystal-on-silicon (LCoS) SLM that modulates the phase of the coherent light to generate the first diffracted beam 128, which corresponds to the principal image, and the second diffracted beam 130, which corresponds to the conjugate image, with the first and second diffracted beams 128, 130 being angularly separated by the first angle α. In this non-restrictive example, the SLM 102 produces a phase shift of the coherent light, where the actual range of the phase shift is not equal to 2π. However, in other examples, the SLM produces a phase shift that is equal to 2π.

[0036] In block 406, the optical component 132 separates the first and second diffracted rays 128, 130 from each other by the second angle θ, which is larger than the first angle α. In a non-restrictive example, the optical component 132 is the diffraction grating 134, which diffractes at least one of the first and second diffracted rays 128, 130. In another non-restrictive example ( Fig. 4) The optical component 232 is the refracting prism that refracts at least one of the first and second diffracted rays.

Claims

[1] A holographic display system (100) for a motor vehicle (106), wherein the holographic display system comprises: a coherent light source (124) for generating a coherent beam of light; a spatial light modulator, SLM (102), with a two-dimensional pixel arrangement (104) for modulating a phase of the coherent light and for generating a first diffracted ray (128) associated with a principal image and a second diffracted ray (130) associated with a conjugate image, wherein the first and second diffracted rays (128, 130) are spaced apart by a first angle (α); an optical component (132) for transmitting at least one of the first and second diffracted rays (128, 130) and for angularly separating the first and second diffracted rays (128, 130) from each other by a second angle (θ) which is larger than the first angle (α), wherein the optical component (132) comprises a diffraction grating (134) or a refracting prism for diffracting at least one of the first and second diffracted rays (128, 130); a display surface (122) arranged relative to the optical component (132) to receive the first diffracted ray (128) from the optical component (132) and to display the main image, wherein the display surface (122) is free of the second diffracted ray (130); and a computer (136), comprising: a processor (138) connected to the coherent light source (124) and the SLM (102); and a memory (140) containing instructions such that the processor (138) is programmed to control the two-dimensional pixel arrangement (104) of the SLM (102) that generates the first and second diffracted beams (128, 130). [2] Holographic display system (100) for a motor vehicle (106) according to claim 1, wherein the SLM (102) is able to generate a phase shift in a range between 0 and 2π, wherein the actual range of the phase shift is not equal to 2π. [3] Holographic display system (100) for a motor vehicle (106) according to claim 2, wherein the coherent light source (124) is a LASER (126). [4] Holographic display system (100) for a motor vehicle (106) according to claim 3, wherein the SLM (102) comprises a liquid crystal on silicon (LCoS) SLM (102). [5] A motor vehicle (106), comprising: a structure (108) that defines a passenger cabin (110); a plurality of reflective surfaces (112) surrounding the passenger cabin (110), wherein the reflective surfaces (112) comprise at least one mirror, a front windscreen (114), a rear windscreen (116), a sunroof (118) and a plurality of side windows (120) surrounding the passenger cabin (110); and a holographic display system (100) connected to the structure (108) and comprising the following: a coherent light source (124) for generating a coherent beam of light; a spatial light modulator, SLM (102), with a two-dimensional pixel arrangement (104) for modulating a phase of the coherent light and for generating a first diffracted ray (128) associated with a principal image and a second diffracted ray (130) associated with a conjugate image, wherein the first and second diffracted rays (128, 130) are spaced apart by a first angle (α); an optical component (132) for transmitting at least one of the first and second diffracted rays (128, 130) and for angularly separating the first and second diffracted rays (128, 130) from each other by a second angle (θ) which is larger than the first angle (α), wherein the optical component (132) comprises a diffraction grating (134) or a refracting prism for diffracting at least one of the first and second diffracted rays (128, 130); a display surface (122) arranged relative to the optical component (132) to receive the first diffracted ray (128) from the optical component (132) and to display the main image, wherein the display surface (122) is free of the second diffracted ray (130); and a computer (136) with: a processor (138) connected to the coherent light source (124) and the SLM (102); and a memory (140) containing instructions such that the processor (138) is programmed to control the two-dimensional pixel arrangement (104) of the SLM (102) that generates the first and second diffracted beams (128, 130). [6] Motor vehicle (106) according to claim 5, wherein the display area (122) comprises a part of the windscreen (114), the rear window (116), the sunroof (118) and / or the side windows (120). [7] Motor vehicle (106) according to claim 6, wherein the holographic display system (100) further comprises a combination glass (346) arranged in the passenger cabin (110) and the display area (122) is a part of the combination glass (346). [8] Motor vehicle (106) according to claim 7, wherein the SLM (102) is able to generate a phase shift in a range between 0 and 2π, wherein an actual range of the phase shift is not equal to 2π.

Images