Head-up display

Abstract

To provide a compact head-up display capable of generating a three-dimensional virtual image object.SOLUTION: An HUD 42 includes: an image-forming part 424 for emitting light for generating a predetermined image; a light guide 426 for propagating light emitted from the image-forming part 424 while totally reflecting the light; an incidence HOE 425 for changing the direction of light so as to totally reflect the light emitted from the image-forming part 424 within the light guide 426; an emission HOE 427 for changing the direction of light so as to emit the light propagated while being totally reflected within the light guide 426 from the light guide 426; and a microlens array 428 for refracting incident light in a predetermined direction and emitting it. The microlens array 428 is provided after the emission HOE 427 in an optical path of light.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to head-up displays. [Background technology]

[0002] In the future autonomous driving society, it is expected that visual communication between vehicles and humans will become increasingly important. For example, it is expected that visual communication between a vehicle and its occupants will become increasingly important. In this regard, visual communication between a vehicle and its occupants can be realized by using a head-up display (HUD). A head-up display can realize so-called AR (Augmented Reality) by projecting an image or video onto a windshield or combiner, and allowing the occupant to view the image by superimposing it on the real space through the windshield or combiner.

[0003] As an example of a head-up display, Patent Document 1 discloses a display device equipped with an optical system for displaying a three-dimensional virtual image using a transparent display medium. The display device projects light onto the windshield or combiner into the driver's field of vision. A part of the projected light passes through the windshield or combiner, while another part is reflected by the windshield or combiner. This reflected light is directed toward the driver's eyes. The driver perceives the reflected light as a virtual image that looks like an object on the other side of the windshield or combiner (outside the vehicle) against the background of real objects seen through the windshield or combiner. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-45103 Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure aims to provide a compact head-up display capable of generating 3D virtual objects. [Means for solving the problem]

[0006] A head-up display according to one aspect of the present disclosure is provided in a vehicle and configured to display a predetermined image toward an occupant of the vehicle, an image generating unit that emits light for generating the predetermined image; a light guide that propagates the light emitted from the image generating unit while totally reflecting the light; a first changer that changes the direction of the light so that the light emitted from the image generating unit is totally reflected within the light guide; The light is transmitted so that the light propagating within the light guide while being totally reflected is emitted from the light guide. diffraction To reflect diffraction A second change unit for changing the an optical element that refracts and emits incident light so as to generate a virtual image as a stereoscopic image; The optical element is provided after the second change portion in the optical path of the light. Effect of the Invention

[0007] According to the present disclosure, it is possible to provide a compact head-up display capable of generating 3D virtual objects. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram of a vehicle system according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic diagram showing a configuration of a HUD of the vehicle system of FIG. [Diagram 3] FIG. 13 is a diagram showing a reference example of a HUD main body having an image generating unit and a microlens array. [Figure 4]3 is a diagram for explaining the HUD main body of FIG. 2. [Diagram 5] FIG. 13 is a schematic diagram showing the configuration of a HUD according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present disclosure (hereinafter, referred to as the present embodiment) will be described with reference to the drawings. For the sake of convenience, the dimensions of each component shown in the drawings may differ from the actual dimensions of each component.

[0010] In addition, in the description of this embodiment, for convenience of description, the "left-right direction", "up-down direction", and "front-rear direction" may be appropriately mentioned. These directions are relative directions set for the HUD (Head-Up Display) 42 shown in FIG. 2. In FIG. 2, U is upward, D is downward, F is forward, and B is rearward. Here, the "left-right direction" is a direction including the "left direction" and the "right direction". The "up-down direction" is a direction including the "upward direction" and the "downward direction". The "front-rear direction" is a direction including the "forward direction" and the "rearward direction". Although the left-right direction is not shown in FIG. 2, it is a direction perpendicular to the up-down direction and the front-rear direction.

[0011] First, a vehicle system 2 according to this embodiment will be described below with reference to Fig. 1. Fig. 1 is a block diagram of the vehicle system 2. A vehicle 1 equipped with the vehicle system 2 is a vehicle (automobile) capable of running in an autonomous driving mode.

[0012] 1, the vehicle system 2 includes a vehicle control unit 3, a vehicle display system 4 (hereinafter simply referred to as the "display system 4"), a sensor 5, a camera 6, and a radar 7. The vehicle system 2 further includes an HMI (Human Machine Interface) 8, a GPS (Global Positioning System) 9, a wireless communication unit 10, a storage device 11, a steering actuator 12, a steering device 13, a brake actuator 14, a brake device 15, an accelerator actuator 16, and an accelerator device 17.

[0013] The vehicle control unit 3 is configured to control the running of the vehicle. The vehicle control unit 3 is configured, for example, by at least one electronic control unit (ECU: Electronic Control Unit). The electronic control unit includes a computer system (for example, SoC (System on a Chip) or the like) including one or more processors and one or more memories, and an electronic circuit configured of active elements such as transistors and passive elements. The processor includes, for example, at least one of a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a GPU (Graphics Processing Unit), and a TPU (Tensor Processing Unit). The CPU may be configured by multiple CPU cores. The GPU may be configured by multiple GPU cores. The memory includes a ROM (Read Only Memory) and a RAM (Random Access Memory). A vehicle control program may be stored in the ROM. For example, the vehicle control program may include an artificial intelligence (AI) program for autonomous driving. The AI ​​program is a program (trained model) constructed by supervised or unsupervised machine learning (particularly, deep learning) using a multi-layer neural network. The RAM may temporarily store a vehicle control program, vehicle control data, and / or surrounding environment information indicating the surrounding environment of the vehicle. The processor may be configured to load a program specified from various vehicle control programs stored in the ROM onto the RAM and execute various processes in cooperation with the RAM. The computer system may also be configured with a non-von Neumann type computer such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array). The computer system may also be configured with a combination of a von Neumann type computer and a non-von Neumann type computer.

[0014] The sensor 5 includes at least one of an acceleration sensor, a speed sensor, and a gyro sensor. The sensor 5 is configured to detect the driving state of the vehicle and output driving state information to the vehicle control unit 3. The sensor 5 may further include a seating sensor that detects whether the driver is sitting in the driver's seat, a face direction sensor that detects the direction of the driver's face, an external weather sensor that detects the external weather conditions, and a human presence sensor that detects whether there is a person in the vehicle. The driver is an example of a passenger of the vehicle 1.

[0015] The camera 6 is a camera including an imaging element such as a CCD (Charge-Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). The camera 6 includes one or more external cameras 6A and an internal camera 6B. The external camera 6A is configured to acquire image data showing the surrounding environment of the vehicle and then transmit the image data to the vehicle control unit 3. The vehicle control unit 3 acquires surrounding environment information based on the transmitted image data. Here, the surrounding environment information may include information on objects (pedestrians, other vehicles, signs, etc.) existing outside the vehicle. For example, the surrounding environment information may include information on attributes of objects existing outside the vehicle and information on the distance and position of the objects relative to the vehicle. The external camera 6A may be configured as a monocular camera or as a stereo camera.

[0016] The internal camera 6B is disposed inside the vehicle and configured to acquire image data showing the occupant. The internal camera 6B functions as a tracking camera that tracks the occupant's viewpoint E. Here, the occupant's viewpoint E may be either the occupant's left eye viewpoint or the occupant's right eye viewpoint. Alternatively, the viewpoint E may be defined as the midpoint of a line segment connecting the left eye viewpoint and the right eye viewpoint.

[0017] The radar 7 includes at least one of a millimeter wave radar, a microwave radar, and a laser radar (e.g., a LiDAR unit). For example, the LiDAR unit is configured to detect the surrounding environment of the vehicle. In particular, the LiDAR unit is configured to obtain 3D mapping data (point cloud data) indicating the surrounding environment of the vehicle, and then transmit the 3D mapping data to the vehicle control unit 3. The vehicle control unit 3 identifies surrounding environment information based on the transmitted 3D mapping data.

[0018] The HMI 8 is composed of an input unit that accepts input operations from the driver, and an output unit that outputs driving information and the like to the driver. The input unit includes a steering wheel, an accelerator pedal, a brake pedal, a driving mode changeover switch that changes the driving mode of the vehicle, and the like. The output unit is a display (excluding the HUD) that displays various driving information. The GPS 9 is configured to acquire current location information of the vehicle and output the acquired current location information to the vehicle control unit 3.

[0019] The wireless communication unit 10 is configured to receive information (e.g., travel information, etc.) about other vehicles around the vehicle from the other vehicles and transmit information (e.g., travel information, etc.) about the vehicle to the other vehicles (vehicle-to-vehicle communication). The wireless communication unit 10 is also configured to receive infrastructure information from infrastructure equipment such as traffic lights and marker lights and transmit travel information of the vehicle 1 to the infrastructure equipment (road-to-vehicle communication). The wireless communication unit 10 is also configured to receive information about pedestrians from portable electronic devices (smartphones, tablets, wearable devices, etc.) carried by pedestrians and transmit vehicle travel information of the vehicle to the portable electronic device (pedestrian-to-vehicle communication). The vehicle may directly communicate with other vehicles, infrastructure equipment, or portable electronic devices in an ad-hoc mode, or may communicate via an access point. The vehicle may also communicate with other vehicles, infrastructure equipment, or portable electronic devices via a communication network not shown. The communication network includes at least one of the Internet, a local area network (LAN), a wide area network (WAN), and a radio access network (RAN). The wireless communication standard is, for example, Wi-Fi (registered trademark), Bluetooth (registered trademark), ZigBee (registered trademark), LPWA, DSRC (registered trademark), or Li-Fi. The vehicle 1 may also communicate with other vehicles, infrastructure equipment, or portable electronic devices using a fifth generation mobile communication system (5G).

[0020] The storage device 11 is an external storage device such as a hard disk drive (HDD) or a solid state drive (SSD). Two-dimensional or three-dimensional map information and / or a vehicle control program may be stored in the storage device 11. For example, the three-dimensional map information may be composed of 3D mapping data (point cloud data). The storage device 11 is configured to output the map information and the vehicle control program to the vehicle control device 3 in response to a request from the vehicle control device 3. The map information and the vehicle control program may be updated via the wireless communication unit 10 and a communication network.

[0021] When the vehicle runs in the autonomous driving mode, the vehicle control unit 3 automatically generates at least one of a steering control signal, an accelerator control signal, and a brake control signal based on the driving state information, the surrounding environment information, the current position information, the map information, and the like. The steering actuator 12 is configured to receive the steering control signal from the vehicle control unit 3 and control the steering device 13 based on the received steering control signal. The brake actuator 14 is configured to receive the brake control signal from the vehicle control unit 3 and control the brake device 15 based on the received brake control signal. The accelerator actuator 16 is configured to receive the accelerator control signal from the vehicle control unit 3 and control the accelerator device 17 based on the received accelerator control signal. In this way, the vehicle control unit 3 automatically controls the running of the vehicle based on the driving state information, the surrounding environment information, the current position information, the map information, and the like. That is, in the autonomous driving mode, the running of the vehicle is automatically controlled by the vehicle system 2.

[0022] On the other hand, when the vehicle 1 runs in the manual driving mode, the vehicle control unit 3 generates a steering control signal, an accelerator control signal, and a brake control signal in accordance with the driver's manual operation of the accelerator pedal, the brake pedal, and the steering wheel. In this way, in the manual driving mode, the steering control signal, the accelerator control signal, and the brake control signal are generated by the driver's manual operation, so that the running of the vehicle is controlled by the driver.

[0023] The display system 4 includes a headlamp 20 , a road surface drawing device 45 , a HUD 42 , and a display control unit 43 .

[0024] The headlamps 20 are disposed on the left and right sides of the front of the vehicle, and include a low beam lamp configured to irradiate a low beam ahead of the vehicle, and a high beam lamp configured to irradiate a high beam ahead of the vehicle 1. Each of the low beam lamp and the high beam lamp has one or more light-emitting elements such as an LED (Light Emitting Diode) or an LD (Laser Diode), and optical members such as a lens and a reflector.

[0025] The road surface drawing device 45 is disposed in the lamp chamber of the headlamp 20. The road surface drawing device 45 is configured to emit a light pattern toward a road surface outside the vehicle. The road surface drawing device 45 has, for example, a light source unit, a drive mirror, an optical system such as a lens and a mirror, a light source drive circuit, and a mirror drive circuit. The light source unit is a laser light source or an LED light source. For example, the laser light source is an RGB laser light source configured to emit red laser light, green laser light, and blue laser light, respectively. The drive mirror is, for example, a MEMS (Micro Electro Mechanical Systems) mirror, a DMD (Digital Mirror Device), a galvanometer mirror, a polygon mirror, or the like. The light source drive circuit is configured to drive and control the light source unit. The light source drive circuit is configured to generate a control signal for controlling the operation of the light source unit based on a signal related to a predetermined light pattern transmitted from the display control unit 43, and then transmit the generated control signal to the light source unit. The mirror drive circuit is configured to drive and control the drive mirror. The mirror driving circuit is configured to generate a control signal for controlling the operation of the driving mirror based on a signal related to a predetermined light pattern transmitted from the display control unit 43, and then transmit the generated control signal to the driving mirror. When the light source unit is an RGB laser light source, the road surface drawing device 45 can draw light patterns of various colors on the road surface by scanning the laser light. For example, the light pattern may be an arrow-shaped light pattern indicating the traveling direction of the vehicle.

[0026] The drawing method of the road surface drawing device 45 may be a raster scan method, a DLP (Digital Light Processing) method, or an LCOS (Liquid Crystal on Silicon) method. When the DLP method or the LCOS method is adopted, the light source unit may be an LED light source. The projection method may be adopted as the drawing method of the road surface drawing device. When the projection method is adopted, the light source unit may be a plurality of LED light sources arranged in a matrix. The road surface drawing device 45 may be disposed in the lamp chambers of the left and right headlamps, respectively, or may be disposed on the vehicle roof, bumper, or grille.

[0027] The display control unit 43 is configured to control the operation of the road surface drawing device 45, the headlamp 20, and the HUD 42. The display control unit 43 is configured by an electronic control unit (ECU). The electronic control unit includes a computer system (e.g., SoC, etc.) including one or more processors and one or more memories, and an electronic circuit configured of active elements such as transistors and passive elements. The processor includes at least one of a CPU, an MPU, a GPU, and a TPU. The memory includes a ROM and a RAM. The computer system may also be configured by a non-von Neumann type computer such as an ASIC or an FPGA. The display control unit 43 may identify the position of the occupant's viewpoint E based on image data acquired by the internal camera 6B. The position of the occupant's viewpoint E may be updated at a predetermined cycle based on the image data, or may be determined only once when the vehicle is started.

[0028] In this embodiment, the vehicle control unit 3 and the display control unit 43 are provided as separate components, but the vehicle control unit 3 and the display control unit 43 may be configured as an integrated unit. In this regard, the display control unit 43 and the vehicle control unit 3 may be configured as a single electronic control unit. Furthermore, the display control unit 43 may be configured by two electronic control units, an electronic control unit configured to control the operation of the headlamp 20 and the road surface drawing device 45, and an electronic control unit configured to control the operation of the HUD 42.

[0029] At least a part of the HUD 42 is located inside the vehicle. Specifically, the HUD 42 is installed at a predetermined location inside the vehicle. For example, the HUD 42 may be disposed inside the dashboard of the vehicle. The HUD 42 functions as a visual interface between the vehicle and the occupant. The HUD 42 is configured to display predetermined information (hereinafter, referred to as HUD information) toward the occupant so that the HUD information is superimposed on the real space outside the vehicle (particularly, the surrounding environment in front of the vehicle). In this way, the HUD 42 functions as an AR (Augmented Reality) display. The HUD information displayed by the HUD 42 is, for example, vehicle driving information related to the driving of the vehicle and / or surrounding environment information related to the surrounding environment of the vehicle (particularly, information related to an object existing outside the vehicle).

[0030] As shown in FIG. 2, the HUD 42 includes a HUD main body 420. The HUD main body 420 includes a housing 422 and an exit window 423. The exit window 423 is a transparent plate that transmits visible light. The HUD main body 420 includes an image generating unit (PGU: Picture Generation Unit) 424, an entrance holographic optical element 425, a light guide 426, an exit holographic optical element 427, and a microlens array 428 inside the housing 422. The entrance holographic optical element 425 and the exit holographic optical element 427 are hereinafter referred to as an entrance HOE 425 and an exit HOE 427. The entrance HOE 425 is an example of a first changer. The exit HOE 427 is an example of a second changer.

[0031] The image generating unit 424 has a light source (not shown), optical components (not shown), a display device 429, and a control board 430. The light source is, for example, a laser light source or an LED light source. The laser light source is, for example, an RGB laser light source configured to emit red laser light, green laser light, and blue laser light, respectively. The optical components include a prism, a lens, a diffusion plate, a magnifying glass, and the like as appropriate. The display device 429 is a light emitting array (a plurality of light source bodies arranged in an array), and the like. Note that the display device is not limited to a light emitting array. For example, the display device may be a device that displays 2D, such as a liquid crystal display, a DMD (Digital Mirror Device), or a micro LED display. The drawing method of the image generating unit 424 may be a raster scan method, a DLP method, or an LCOS method. When the DLP method or the LCOS method is adopted, the light source of the image generating unit 424 may be an LED light source. Note that when the liquid crystal display method is adopted, the light source of the image generating unit 424 may be a white LED light source.

[0032] The control board 430 is configured to control the operation of the display device 429. The control board 430 is equipped with a processor such as a CPU (Central Processing Unit) and a memory, and the processor executes a computer program read from the memory to control the operation of the display device 429. The control board 430 is configured to generate a control signal for controlling the operation of the display device 429 based on image data transmitted from the display control unit 43, and then transmit the generated control signal to the display device 429. The control board 430 may be configured as a part of the display control unit 43.

[0033] The incident HOE 425 is disposed inside the light guide 426 on the optical path of the light emitted from the image generating unit 424. The incident HOE 425 is configured to diffract the light emitted from the image generating unit 424 and incident on the light guide 426 in a predetermined direction. The incident HOE 425 is a transmission type HOE that transmits and diffracts the incident light. For example, the incident HOE 425 is configured by sandwiching a transparent glass substrate with a photopolymer film attached to its surface between two base materials made of resin or glass. The incident HOE 425 may be disposed outside the light guide 426. In this case, the incident HOE 425 is configured to diffract the light emitted from the image generating unit 424 so that the light emitted from the image generating unit 424 enters the light guide 426 at a predetermined angle.

[0034] The light guide 426 is made of a transparent resin such as acrylic, polycarbonate, etc. The light guide 426 transmits the light diffracted by the incident HOE 425 while totally reflecting it.

[0035] The output HOE 427 is disposed inside the light guide 426 on the optical path of the light propagated in the light guide 426. The output HOE 427 is configured to diffract the light propagated in the light guide 426 in a predetermined direction so that the light propagated in the light guide 426 is output from the light guide 426 toward the microlens array 428. The output HOE 427 is a transmission type HOE that transmits and diffracts the incident light. For example, the output HOE 427 is configured by sandwiching a transparent glass substrate with a photopolymer film attached to its surface between two base materials made of resin or glass. The output HOE 427 may be a reflection type HOE that reflects the incident light and diffracts it in a predetermined direction.

[0036] The microlens array 428 is disposed on the optical path of the light emitted from the light guide 426. The microlens array 428 is configured by arranging a plurality of minute convex lenses in a two-dimensional shape. The microlens array 428 refracts the light that is emitted from the light guide 426 and enters the microlens array 428 in a predetermined direction and emits the light toward the windshield 18. The light emitted from the microlens array 428 is emitted as light that generates a 2D image (planar image) of the display device 429 as a 3D image (stereoscopic image) by a light field method.

[0037] The light emitted from the HUD main body 420 is irradiated onto the windshield 18 (for example, the front window of the vehicle 1). Next, a portion of the light irradiated from the HUD main body 420 onto the windshield 18 is reflected toward the occupant's viewpoint E. As a result, the occupant recognizes the light (predetermined 3D image) emitted from the HUD main body 420 as a 3D virtual image formed at a predetermined distance in front of the windshield 18. In this way, the image displayed by the HUD 42 is superimposed on the real space in front of the vehicle 1 through the windshield 18, so that the occupant can visually recognize the 3D virtual image object I formed by the predetermined image as floating above the road located outside the vehicle.

[0038] Next, the HUD main body 420 according to this embodiment will be described below with reference to Fig. 3 and Fig. 4. Fig. 3 is a diagram showing a reference example of a HUD main body 420A having an image generating section 424A and a microlens array 428A. Fig. 4 is a diagram for explaining the HUD main body 420 of Fig. 2. For convenience of explanation, the explanation of the members having the same reference numbers as the members already explained in the above explanation will be omitted.

[0039] 3 has a housing 422A and an exit window 423A. The HUD body 420A has an image generating unit 424A and a microlens array 428A inside the housing 422A. The image generating unit 424A has a light source (not shown), an optical component (not shown), a display device 429A, and a control board 430A. The control board 430A generates a control signal for controlling the operation of the display device 429A based on image data transmitted from the display control unit 43, and then transmits the generated control signal to the display device 429A.

[0040] Microlens array 428A is disposed opposite image generating section 424A so as to be disposed on the optical path of light emitted from image generating section 424A. Microlens array 428A refracts the light emitted from image generating section 424A and incident on microlens array 428A in a predetermined direction and emits the light toward windshield 18. By the light field method, the light emitted from microlens array 428A is emitted as light that generates a 2D image (planar image) of display device 429A as a 3D image (stereoscopic image).

[0041] The display device 429A is disposed so that the occupant can recognize the light (predetermined image) emitted from the HUD main body 420A as a virtual image formed at a predetermined distance in front of the windshield 18. That is, the display device 429A is disposed away from the microlens array 428A by a distance corresponding to the predetermined distance in front of the windshield 18. This increases the overall size of the HUD main body 420A (housing 422A).

[0042] The HUD main body 420 of this embodiment in Fig. 4 uses an incident HOE 425, a light guide 426, and an output HOE 427 to create a virtual image of the display device 429A in Fig. 3. This allows the occupant to recognize the light (predetermined image) output from the HUD main body 420 as a virtual image formed at a predetermined distance in front of the windshield 18, without increasing the overall size of the HUD main body 420 (housing 422).

[0043] 4, the light of an image formed by a display device 429 is incident on a light guide 426, propagates through an incident HOE 425 by repeating total reflection within the light guide 426, and is emitted from the light guide 426 through an output HOE 427. The microlens array 428 refracts the light that is emitted from the light guide 426 and enters the microlens array 428 in a predetermined direction and emits it toward the windshield 18. By the light field method, the light emitted from the microlens array 428 is emitted as light that generates a 2D image (planar image) of the display device 429 as a 3D image (stereoscopic image).

[0044] In the HUD main body 420 of this embodiment, the light emitted from the light guide 426 is incident on the microlens array 428 along the same optical path as the light (two-dot chain line) emitted from the virtual image 429' of the display device by using the incident HOE 425, the light guide 426, and the output HOE 427. Therefore, it is not necessary to provide the display device 429 at a position opposite the microlens array 428, and the size of the HUD main body 420 can be prevented from increasing. In addition, since the light incident into the light guide 426 is repeatedly reflected, a long optical path length can be obtained without forming the light guide 426 long. This makes it possible to lengthen the distance at which the virtual image object I is visible (the virtual image object I is generated at a distant position). The output HOE 427 may be structured to have a lens effect, so that the magnification at which the virtual image object I is generated and the virtual image position of the virtual image object I can be changed.

[0045] Thus, in this embodiment, the light guide 426 propagates the light emitted from the image generating unit 424 while totally reflecting it, and emits it toward the microlens array 428. The input HOE 425 changes the direction of the light so that the light emitted from the image generating unit 424 is totally reflected in the light guide 426. The output HOE 427 changes the direction of the light so that the light propagating while totally reflecting in the light guide 426 is emitted from the light guide 426. This makes it possible to lengthen the optical path length while preventing the HUD from becoming large. In addition, the microlens array 428 refracts the light emitted from the light guide 426 and incident on the microlens array 428 in a predetermined direction and emits it. This makes it possible to generate a 3D virtual image object I. In addition, by generating the 3D virtual image object I using the microlens array 428, a compact structure can be realized compared to the case of generating a virtual image object using a concave mirror. As a result, it is possible to provide a head-up display capable of generating a 3D virtual image object with a compact structure.

[0046] Although the embodiment of the present disclosure has been described above, it goes without saying that the technical scope of the present disclosure should not be interpreted as being limited by the description of the present embodiment. The present embodiment is merely an example, and it is understood by those skilled in the art that various modifications of the embodiment are possible within the scope of the invention described in the claims. The technical scope of the present disclosure should be determined based on the scope of the invention described in the claims and its equivalents.

[0047] FIG. 5 is a schematic diagram showing the configuration of a HUD 142 according to a modified example. As shown in FIG. 5, the HUD 142 according to the modified example is composed of a HUD main body 420 and a combiner 143. The combiner 143 is provided inside the windshield 18 as a structure separate from the windshield 18. The combiner 143 is, for example, a transparent plastic disk, and is irradiated with light emitted by a microlens array 428 instead of the windshield 18. As a result, a part of the light irradiated from the HUD main body 420 to the combiner 143 is reflected toward the viewpoint E of the occupant, similar to the case where light is irradiated onto the windshield 18. As a result, the occupant can recognize the light (predetermined image) emitted from the HUD main body 420 as a virtual image formed at a predetermined distance in front of the combiner 143 (and the windshield 18).

[0048] In the present embodiment, the direction of light is changed using a holographic optical element, but the present invention is not limited to this. For example, a diffractive optical element (DOE) or the like may be used.

[0049] In the above embodiment, the 3D virtual image object is generated using the microlens array 428, but the present invention is not limited to this. An optical element having the same effect as the microlens array, for example, an HOE, may be used.

[0050] This application is based on Japanese Patent Application No. 2018-225179 filed on November 30, 2018, the contents of which are incorporated herein by reference.

Claims

1. A head-up display provided in a vehicle and configured to display a predetermined image toward an occupant of the vehicle, an image generating unit that emits light for generating the predetermined image; a light guide that transmits the light emitted from the image generating unit while totally reflecting the light; a first changer that changes the direction of the light so that the light emitted from the image generating unit is totally reflected within the light guide; A second change portion that transmits and diffracts the light or reflects and diffracts the light so that the light propagating while being totally reflected within the light guide is emitted from the light guide; an optical element that refracts and emits incident light so as to generate a virtual image as a stereoscopic image; A head-up display, wherein the optical element is provided after the second change portion in the optical path of the light.

2. The head-up display according to claim 1 , wherein the second change unit has a structure having a lens effect capable of changing a magnification for generating a virtual image object formed by the predetermined image or a virtual image position of the virtual image object.

3. The head-up display of claim 1 , wherein the optical element is a holographic optical element.

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