Head-up display

Abstract

To provide a light emission device capable of preventing heat damage caused by external light without degrading light emission function.SOLUTION: A light emission device (20) includes: a light source (24); an optical member (27) which enlarges light by transmitting or reflecting the light emitted from the light source (24) and emits the light to the outside, and an optical isolator (70) which can transmit light while preventing external light from entering the light source (24).SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] It is expected that on public roads there will be a mixture of vehicles operating in autonomous mode and vehicles operating in manual mode.

[0003] 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.

[0004] 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. Some 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.

[0005] Furthermore, when external light such as sunlight penetrates into the head-up display, the external light is concentrated on the display, causing a local temperature rise, which may lead to a disturbance in the image display or thermal damage to the display. To prevent such problems, a configuration that enhances the heat dissipation of the display and a configuration that provides a plate that reflects infrared rays between the display and the reflecting part are known (see Patent Document 2). However, Patent Document 2 requires a separate component to suppress the temperature rise of the display, which leads to high costs.

[0006] The display device has a reflector that reflects the light image formed on the screen toward a windshield or a combiner. When a concave mirror is used as the reflector, a high-definition concave mirror is required, which leads to high costs for the display device.

[0007] Furthermore, in existing head-up displays, there is room for improvement in terms of the configuration for expanding the display range of a virtual image. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2018-45103 [Patent Document 2] Japanese Patent Publication No. 2005-313733 Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present disclosure is to provide a light emitting device, a head-up display, a vehicle lamp, and a projector that are capable of preventing the occurrence of heat damage caused by external light without reducing the light emitting function.

[0010] An object of the present disclosure is to provide a head-up display that can realize a reflector at low cost without significantly degrading the image quality of a virtual image.

[0011] An object of the present disclosure is to provide a head-up display that can realize a reflector at low cost.

[0012] An object of the present disclosure is to provide a head-up display capable of expanding the image display range at low cost. [Means for solving the problem]

[0013] A light output device according to one aspect of the present disclosure includes: A light source; an optical member that transmits or reflects light emitted from the light source to expand the light and irradiate it to the outside; and an optical isolator that is capable of transmitting the light while preventing external light from entering the light source.

[0014] According to the above configuration, it is possible to provide a light emitting device capable of preventing the occurrence of heat damage caused by external light entering the light source without deteriorating the light emitting function.

[0015] A head-up display according to one aspect of the present disclosure includes: A head-up display provided in a vehicle and including the light emitting device described above, The light emitting device is configured to display a predetermined image toward an occupant of the vehicle, The optical member transmits or reflects the light emitted by the light source so that the light is irradiated onto a windshield or a combiner, The optical isolator is disposed at a position where the light passes between the light source and the optical member, or between the optical member and the windshield or the combiner.

[0016] According to the above configuration, it is possible to provide a head-up display capable of preventing the occurrence of heat damage caused by external light entering the light source without reducing the light emission function.

[0017] A vehicle lamp according to one aspect of the present disclosure includes: A vehicle lamp provided in a vehicle and including the light emitting device described above, The light emitting device is configured to emit light to an area around the vehicle, The optical isolator is disposed at a position where the light passes between the light source and the optical member or between the optical member and an outer lens of the vehicle lamp.

[0018] According to the above configuration, it is possible to provide a vehicle lamp capable of preventing the occurrence of heat damage caused by external light entering the light source without reducing the light emission function.

[0019] A projector according to one aspect of the present disclosure includes: A projector including the light output device described above, the light output device is configured to display a predetermined image on an object external to the projector; The optical isolator is disposed at a position between the light source and the optical member or between the optical member and the object through which the light passes.

[0020] According to the above configuration, it is possible to provide a projector that can prevent the occurrence of heat damage caused by external light entering the light source without deteriorating the light emission function.

[0021] A head-up display according to one aspect of the present disclosure includes: 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 a first light for generating a first image among the predetermined images and a second light for generating a second image among the predetermined images; A reflecting unit that reflects the first light and the second light emitted by the image generating unit so that the first light and the second light are irradiated to a windshield or a combiner, the reflecting portion has a reflecting surface including a first reflecting area that reflects the first light and a second reflecting area that reflects the second light, The first reflective area has a first surface roughness and the second reflective area has a second surface roughness that is rougher than the first surface roughness.

[0022] According to the above configuration, the second reflection area has a rougher surface than the first reflection area. Therefore, the second reflection area can be formed at a lower cost than the first reflection area. On the other hand, the first reflection area has a smoother surface than the second reflection area. Therefore, the first image can be recognized as a high-quality virtual image. Therefore, the reflection section can be realized at a low cost without significantly degrading the image quality of the virtual image.

[0023] A head-up display according to one aspect of the present disclosure includes: 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 a first light for generating a first image among the predetermined images and a second light for generating a second image among the predetermined images; A reflecting unit that reflects the first light and the second light emitted by the image generating unit so that the first light and the second light are irradiated to a windshield or a combiner, The reflecting portion includes a concave mirror that reflects the first light and a plane mirror that reflects the second light.

[0024] According to the above configuration, since the reflecting portion is composed of a concave mirror and a plane mirror, the reflecting portion can be realized at low cost.

[0025] A head-up display according to one aspect of the present disclosure includes: 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 reflecting unit that reflects the light emitted by the image generating unit so that the light is irradiated onto a windshield or a combiner, A region on the light output surface of the image generating unit that can form a rectangular maximum display range in which a first image that is a part of the predetermined image is displayed is defined as a first region, and a region other than the first region is defined as a second region; A second image different from the first image is displayed by the light emitted from the second region outside the maximum display range in which the first image can be displayed by the light emitted from the first region.

[0026] According to the above configuration, since the second image can be displayed outside the maximum rectangular display range in which the first image is displayed, the image display range can be made wider than ever before. Effect of the Invention

[0027] According to the present disclosure, it is possible to provide a light emitting device, a head-up display, a vehicle lamp, and a projector that are capable of preventing the occurrence of heat damage caused by external light without reducing the light emitting function.

[0028] According to the present disclosure, it is possible to provide a head-up display capable of realizing a reflecting portion at low cost without significantly degrading the image quality of a virtual image.

[0029] According to the present disclosure, it is possible to provide a head-up display capable of realizing a reflector at low cost.

[0030] According to the present disclosure, it is possible to provide a head-up display capable of expanding the image display range at low cost. [Brief description of the drawings]

[0031] [Figure 1] 1 is a block diagram of a vehicle system including a head-up display (HUD) as a light irradiation device according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a schematic diagram of a HUD according to a first embodiment. [Diagram 3] 3 is a cross-sectional view of an optical isolator provided in the HUD of FIG. 2. [Figure 4] 4 is a schematic diagram for explaining a magnetic field of the optical isolator in FIG. 3. [Diagram 5] 4 is a schematic diagram illustrating the function of the optical isolator in FIG. 3. [Figure 6] 4 is a schematic diagram illustrating the function of the optical isolator in FIG. 3. [Figure 7] FIG. 1 is a diagram showing a state in which external light is incident on a HUD that does not include an optical isolator. [Figure 8] 3 is a diagram showing a state in which external light is incident on the HUD in FIG. 2. [Figure 9] FIG. 13 is a schematic diagram of a HUD according to a first modified example. [Figure 10] FIG. 13 is a schematic diagram of a HUD according to a second modified example. [Figure 11] FIG. 11 is a vertical cross-sectional view of a vehicle lamp which also serves as a light irradiation device according to a second embodiment. [Figure 12] FIG. 11 is a schematic diagram of a HUD according to a third embodiment. [Figure 13A] 13 is a schematic diagram illustrating the concave mirror of FIG. 12. [Figure 13B] 13B is a cross-sectional view of the concave mirror of FIG. 13A taken along line IIIB-IIIB and seen from the direction of the arrows. [Figure 13C] FIG. 13C is a partially enlarged view showing region IIIC in FIG. 13B. [Figure 14] 4 is a schematic diagram illustrating an example of an area on the windshield that is irradiated with light emitted by a HUD. FIG. [Figure 15A] 13A and 13B are schematic diagrams illustrating concave mirrors according to modified examples. [Figure 15B] 15B is a cross-sectional view of the concave mirror of FIG. 15A taken along line VB-VB and seen from the direction of the arrows. [Figure 16A] 13A and 13B are schematic diagrams illustrating a concave mirror according to a fourth embodiment. [Figure 16B] 16B is a cross-sectional view of the concave mirror of FIG. 16A taken along line VIB-VIB and seen from the direction of the arrows. [Figure 17]4 is a schematic diagram illustrating an example of an area on the windshield that is irradiated with light emitted by a HUD. FIG. [Figure 18] FIG. 13 is a schematic diagram of a HUD according to a fifth embodiment. [Figure 19] 4 is a schematic diagram illustrating a reflecting section viewed from an image generating section; FIG. [Figure 20] 4 is a schematic diagram illustrating an example of an area on the windshield that is irradiated with light emitted by a HUD. FIG. [Figure 21] FIG. 13 is a schematic diagram of a HUD according to a sixth embodiment. [Figure 22] FIG. 13 is a schematic diagram of a HUD according to a seventh embodiment. [Diagram 23] 4 is a schematic diagram illustrating a reflecting section viewed from an image generating section; FIG. [Figure 24] 4 is a schematic diagram illustrating an example of an area on the windshield that is irradiated with light emitted by a HUD. FIG. [Diagram 25] FIG. 13 is a schematic diagram of a HUD according to an eighth embodiment. [Figure 26] FIG. 13 is a schematic diagram showing the configuration of a HUD according to a ninth embodiment. [Figure 27A] 11 is a diagram showing an example of an exit surface image generated by an image generating unit of a HUD according to a comparative example. FIG. [Figure 27B] 27B is a diagram showing the exit surface image shown in FIG. 27A when it is displayed as a virtual image. [Figure 28] 13A and 13B are diagrams illustrating an example of an exit surface image generated by an image generating unit of a HUD according to a ninth embodiment. [Figure 29] 29 is a diagram showing the exit surface image shown in FIG. 28 displayed as a virtual image. [Diagram 30] FIG. 13 is a schematic diagram showing a HUD according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Hereinafter, an embodiment of the present disclosure 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.

[0033] 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) 20 shown in FIG. 2. 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.

[0034] First, a vehicle system 2 equipped with a HUD 20 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.

[0035] 1, the vehicle system 2 includes a vehicle control unit 3, a sensor 5, a camera 6, a radar 7, an HMI (Human Machine Interface) 8, a GPS (Global Positioning System) 9, a wireless communication unit 10, and a storage device 11. The vehicle system 2 also includes 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. The vehicle system 2 also includes a HUD 20.

[0036] The vehicle control unit 3 is configured to control the traveling of the vehicle 1. 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) having one or more processors and a memory, and an electronic circuit configured of active elements such as transistors and passive elements such as resistors. 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 1. 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). Furthermore, the computer system may be configured with a combination of a von Neumann type computer and a non-von Neumann type computer.

[0037] 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 1 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 a person is inside the vehicle.

[0038] The camera 6 is a camera including an imaging element such as a CCD (Charge-Coupled Device) or a CMOS (Complementary MOS), etc. 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 1 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.) present outside the vehicle 1. For example, the surrounding environment information may include information on attributes of objects present outside the vehicle 1 and information on the distance and position of the objects relative to the vehicle 1. The external camera 6A may be configured as a monocular camera or as a stereo camera.

[0039] The internal camera 6B is disposed inside the vehicle 1 and configured to acquire image data showing the occupant. The internal camera 6B functions, for example, as an eye tracking camera that tracks the occupant's viewpoint E (described later in FIG. 2). The internal camera 6B is provided, for example, near the rearview mirror or inside the instrument panel.

[0040] 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 1. In particular, the LiDAR unit is configured to obtain 3D mapping data (point cloud data) indicating the surrounding environment of the vehicle 1, 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.

[0041] The HMI 8 is composed of an input unit that accepts input operations from the driver, and an output unit that outputs driving information, etc. 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 1, etc. The output unit is a display (excluding the HUD) that displays various driving information.

[0042] The GPS 9 is configured to acquire current position information of the vehicle 1 and output the acquired current position information to the vehicle control unit 3.

[0043] The wireless communication unit 10 is configured to receive information (e.g., travel information, etc.) about other vehicles around the vehicle 1 from the other vehicles and transmit information (e.g., travel information, etc.) about the vehicle 1 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 1 to the portable electronic device (pedestrian-to-vehicle communication). The vehicle 1 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 1 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).

[0044] 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.

[0045] When the vehicle 1 travels 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 traveling of the vehicle 1 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 traveling of the vehicle 1 is automatically controlled by the vehicle system 2.

[0046] 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 1 is controlled by the driver.

[0047] As described above, the driving mode includes an automatic driving mode and a manual driving mode. The automatic driving mode includes, for example, a fully automatic driving mode, an advanced driving assistance mode, and a driving assistance mode. In the fully automatic driving mode, the vehicle system 2 automatically performs all driving control, including steering control, braking control, and accelerator control, and the driver is not in a state where he can drive the vehicle 1. In the advanced driving assistance mode, the vehicle system 2 automatically performs all driving control, including steering control, braking control, and accelerator control, and the driver is in a state where he can drive the vehicle 1 but does not drive the vehicle 1. In the driving assistance mode, the vehicle system 2 automatically performs some driving control, including steering control, braking control, and accelerator control, and the driver drives the vehicle 1 under the driving assistance of the vehicle system 2. On the other hand, in the manual driving mode, the vehicle system 2 does not automatically perform driving control, and the driver drives the vehicle 1 without the driving assistance of the vehicle system 2.

[0048] The HUD 20 is configured to display predetermined information (hereinafter referred to as HUD information) as an image toward the occupant of the vehicle 1 so that the HUD information is superimposed on the real space outside the vehicle 1 (particularly, the surrounding environment in front of the vehicle 1). The HUD information displayed by the HUD 20 is, for example, vehicle driving information related to the driving of the vehicle 1 and / or surrounding environment information related to the surrounding environment of the vehicle 1 (particularly, information related to objects existing outside the vehicle 1). The HUD 20 is an AR display that functions as a visual interface between the vehicle 1 and the occupant.

[0049] At least a portion of the HUD 20 is located inside the vehicle 1. Specifically, the HUD 20 is installed at a predetermined location inside the vehicle 1. For example, the HUD 20 may be disposed in the dashboard of the vehicle 1.

[0050] The HUD 20 includes a picture generation unit (PGU) 24 and a control unit 25. The image generating unit 24 is configured to emit light for generating a predetermined image to be displayed toward an occupant of the vehicle 1.

[0051] The control unit 25 is configured to control the operation of each part of the HUD 20. The control unit 25 is connected to the vehicle control unit 3, and controls the operation of each part of the HUD 20, such as the image generation unit 24, based on vehicle driving information, surrounding environment information, and the like transmitted from the vehicle control unit 3. Note that, in this embodiment, the vehicle control unit 3 and the control unit 25 are provided as separate components, but the vehicle control unit 3 and the control unit 25 may be configured as an integrated unit. For example, the vehicle control unit 3 and the control unit 25 may be configured as a single electronic control unit.

[0052] First embodiment 2 is a schematic diagram of the HUD 20 according to the first embodiment, as viewed from the side of the vehicle 1. As shown in FIG. 2, the HUD 20 includes a HUD main body 21 (an example of a light emitting device). The HUD main body 21 includes a housing 22 and an emission window 23. The emission window 23 is made of a transparent plate that transmits light. The HUD main body 21 includes, inside the housing 22, an image generating unit (PGU: Picture Generation Unit) 24, a plane mirror 26 (an example of a reflecting unit), a concave mirror 27 (an example of a reflecting unit), an optical isolator 70, and a control board 29.

[0053] The image generating unit 24 is configured to emit light for generating a predetermined image to be displayed toward the occupant of the vehicle 1. Although detailed illustration is omitted, the image generating unit 24 has a light source, optical components, and a display device. 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 optical components transmit the light emitted from the light source and emit it toward the display device. The display device is a liquid crystal display, a DMD (Digital Mirror Device), or the like. The drawing method of the image generating unit 24 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 may be an LED light source. Note that, when the liquid crystal display method is adopted, the light source may be a white LED light source.

[0054] Plane mirror 26 is disposed at a position where it can reflect the light emitted from image generating unit 24 in a direction toward concave mirror 27. Note that, for example, a lens may be used as an optical element instead of plane mirror 26. When a lens is used, it is preferable to adjust the positional relationship among image generating unit 24, the lens, and concave mirror 27 so that the light emitted from image generating unit 24 passes through the lens and heads toward concave mirror 27.

[0055] The concave mirror 27 is disposed on the optical path of the light emitted from the image generating unit 24 and reflected by the plane mirror 26. The concave mirror 27 is configured to reflect the light emitted from the image generating unit 24 toward the windshield 18 (for example, the front window of the vehicle 1). The concave mirror 27 has a reflective surface curved concavely to form a predetermined image, and reflects the light image emitted from the image generating unit 24 and formed at a predetermined magnification. That is, the concave mirror 27 reflects the light emitted from the image generating unit 24 to magnify the light and irradiate it outside the HUD 20. The concave mirror 27 has a drive mechanism (not shown). The drive mechanism can rotate the orientation of the concave mirror 27 based on a control signal transmitted from the control board 29.

[0056] The control board 29 constituting the control unit 25 is configured to control the operation of the image generating unit 24. The control board 29 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 image generating unit 24. For example, the control board 29 generates a control signal for controlling the operation of the image generating unit 24 based on vehicle driving information, surrounding environment information, and the like transmitted from the vehicle control unit 3, and transmits the generated control signal to the image generating unit 24. The control board 29 may also control the concave mirror 27 to change its orientation.

[0057] The optical isolator 70 is an optical filter disposed between the concave mirror 27 and the exit window 23. The optical isolator 70 is provided at a position through which light emitted from the image generating unit 24, reflected by the plane mirror 26 and the concave mirror 27, and proceeding toward the windshield 18 passes. The optical isolator 70 is also provided at a position through which external light that enters the inside of the vehicle 1 from the outside, is reflected by the concave mirror 27 and the plane mirror 26, and proceeds toward the image generating unit 24 passes.

[0058] FIG. 3 is a cross-sectional view of the optical isolator 70. The optical isolator 70 is a member that can transmit the light emitted from the image generating unit 24, while blocking external light from outside the vehicle 1 to prevent the external light from entering the image generating unit 24. As shown in Fig. 2 and Fig. 3, the optical isolator 70 includes two polarizers (a first polarizing plate 71 and a second polarizing plate 72) and a Faraday element 73. The Faraday element 73 is disposed between the first polarizing plate 71 and the second polarizing plate 72 on the optical path of the light emitted from the image generating unit 24.

[0059] The first polarizing plate 71 (an example of a first polarizer) and the second polarizing plate 72 (an example of a second polarizer) transmit only light polarized in a specific direction, and are, for example, linear polarizing plates that align the vibration direction of transmitted light in a certain direction. For the first polarizing plate 71 and the second polarizing plate 72, for example, polarizing glass, a polarizing beam splitter (PBS), a prism-type polarizer using birefringent crystals, a wire grid-type polarizer, etc. can be used. The first polarizing plate 71 is arranged to transmit light having only a specific vibration direction component. In addition, the second polarizing plate 72 is arranged to transmit light having only a vibration direction component different from the specific vibration direction component transmitted by the first polarizing plate 71. The first polarizing plate 71 and the second polarizing plate 72 may be configured as an absorptive polarizing plate that removes polarization components in unnecessary directions from the optical path by absorption, or may be configured as a reflective polarizing plate that reflects polarization components in unnecessary directions toward the incident direction. However, when the optical isolator 70 is disposed at the position of the exit window 23 of the HUD main body 21 as in this embodiment, it is preferable to employ an absorptive polarizing plate that is unlikely to cause glare due to the light reflected by the optical isolator 70. The first polarizing plate 71 and the second polarizing plate 72 may each include a filter for blocking at least one of ultraviolet light and infrared light.

[0060] The Faraday element 73 includes a housing 74, a Faraday rotator 75, and a magnet 76. The housing 74 is formed in a cylindrical shape and houses the Faraday rotator 75 and the magnet 76 therein. The housing 74 is made of a magnetic material such as Fe. The housing 74 not only serves to protect the Faraday rotator 75 and the magnet 76, but also functions as a yoke that induces the magnetic flux of the magnet 76.

[0061] The Faraday rotator 75 is composed of a base layer 75A, a Faraday layer 75B provided on the base layer 75A, and a protective layer 75C provided on the Faraday layer 75B. The base layer 75A is composed of a transparent material that is unlikely to cause distortion, such as glass or a crystalline material.

[0062] The Faraday layer 75B is a layer made of a material that exhibits the Faraday effect, which rotates the polarization direction of light when a magnetic field is applied. The material that makes up the Faraday layer 75B is not particularly limited, but for example, bismuth-substituted rare earth iron garnet ((RBi)3Fe5O 12 ), yttrium iron garnet (Y3Fe5O 12 ), terbium gallium garnet (Tb3Ga5O 12 ), Faraday rotation glass, etc. may be used. Note that a material having a nanogranular structure consisting of a fluoride matrix and nm-sized magnetic metal granules may be used as the Faraday layer 75B. Examples of materials having a nanogranular structure include Fe 26 Al 28 F 46 , Fe 13 Co 10 Al 22 F 55 , Fe 25 Y 23 F 52 , Fe 21 Co 14 Y 24 F 41 , Bi-YIG, etc.

[0063] The protective layer 75C is a layer provided to cover the faraday layer 75B in order to prevent deterioration of the faraday layer 75B. The protective layer 75C is made of, for example, SiO2.

[0064] The magnet 76 is used to apply a magnetic field to the Faraday rotator 75. The magnet 76 is arranged around the Faraday rotator 75. For example, a single cylindrical magnet may be used as the magnet 76. In the case of a cylindrical magnet, the Faraday rotator 75 is arranged at a position corresponding to the center hole of the magnet. For example, a permanent magnet may be used as the magnet 76. Note that the magnet 76 may be a combination of a pair of magnets with a Faraday rotator arranged between them. When a pair of magnets is used, the magnetic fields applied to the Faraday rotator 75 must be in the same direction.

[0065] FIG. 4 is a schematic diagram for explaining the magnetic field applied to the Faraday element 73 of the optical isolator 70. As shown in FIG. As shown in FIG. 4, the magnet 76 is arranged so that, for example, one end on the side in contact with the housing 74 is an S pole, and the other end (the end closer to the Faraday rotator 75) is an N pole. In addition, the housing 74 made of a magnetic material is formed in a shape in which both ends (end faces 74A, 74B) are inwardly recessed in cross section, that is, in a U-shape facing each other. Therefore, the magnetic field lines F emanating from the N pole side of the magnet 76 head toward the end face 74A of the housing 74 on the second polarizing plate 72 side, pass through the housing 74 from the end face 74A, emanate from the end face 74B on the first polarizing plate 71 side, and return to the N pole. As a result, the magnetic field lines F formed by the magnet 76 and the housing 74 pass through the Faraday rotator 75 along the direction D from the first polarizing plate 71 to the second polarizing plate 72. In this way, the Faraday rotator 75 is at least partially covered by the housing 74 made of a magnetic material. The housing 74 is configured to have a so-called yoke structure. This allows the Faraday rotator 75 to be placed in a magnetic field in a desired direction as indicated by magnetic field lines F. In addition, since it is possible to prevent the magnetic field from leaking outside the housing 74, it is possible to prevent adverse effects on members other than the Faraday element 73.

[0066] Next, the function of the optical isolator 70 will be described with reference to Fig. 2 and Fig. 5 to Fig. 8. Fig. 5 and Fig. 6 are schematic diagrams for explaining the function of the optical isolator 70. Fig. 7 is a diagram showing a state in which external light is incident on a HUD not equipped with an optical isolator. Fig. 8 is a diagram showing a state in which external light is incident on the HUD 20 of this embodiment. 5 and 6, for ease of explanation, the size of the Faraday rotator 75 (particularly, the length along the light traveling direction) is shown enlarged.

[0067] First, as shown in Fig. 2, the light emitted from the image generating unit 24 is reflected by the plane mirror 26 and the concave mirror 27 and enters the first polarizing plate 71 of the optical isolator 70. Then, as shown in Fig. 5, the first polarizing plate 71 transmits light having only a specific vibration direction component out of the light L1a emitted from the image generating unit 24, and emits it toward the Faraday element 73. Specifically, when the unpolarized light emitted from the image generating unit 24 passes through the first polarizing plate 71, the first polarizing plate 71 absorbs, for example, the horizontal component of the electric field. As a result, the light L1b after passing through the first polarizing plate 71 becomes linearly polarized light having only a vertical component.

[0068] Next, the light L1b (linearly polarized light having only a vertical component) emitted from the first polarizing plate 71 enters the Faraday element 73 (the Faraday rotator 75 of the Faraday element 73). As described in FIG. 4, the magnetic field lines F passing through the Faraday rotator 75 are aligned along the direction D from the first polarizing plate 71 to the second polarizing plate 72. That is, the traveling direction of the light L1b incident on the Faraday rotator coincides with the direction of the magnetic field (magnetic field) applied to the Faraday rotator 75. Therefore, due to the Faraday effect of the Faraday layer 75B, the light L1b, which is linearly polarized light having only a vertical component, is emitted from the Faraday rotator 75 as light L1c rotated, for example, by 45° clockwise.

[0069] Next, the light L1c whose polarization plane has been rotated 45° clockwise by the Faraday rotator 75 is incident on the second polarizing plate 72. The second polarizing plate 72 is disposed so that its polarization direction is oriented so as to be capable of transmitting the light L1c whose polarization direction has been rotated 45° clockwise. That is, the light that can transmit through the second polarizing plate 72 is light that has been rotated 45° clockwise with respect to the light having only a vertical component that has been transmitted through the first polarizing plate 71. Therefore, the light L1c that has been rotated 45° clockwise by the Faraday rotator 75 passes through the second polarizing plate 72 as is, and is irradiated onto the windshield 18.

[0070] Returning to FIG. 2, a portion of the light that is transmitted through the Faraday element 73 (the first polarizing plate 71, the Faraday element 73, and the second polarizing plate 72) and irradiated onto the windshield 18 is reflected toward the occupant's viewpoint E. As a result, the occupant recognizes the light emitted from the HUD main body 21 as a virtual image (an example of a predetermined image) formed at a predetermined distance in front of the windshield 18. In this way, the image displayed by the HUD 20 is superimposed on the real space in front of the vehicle 1 through the windshield 18, so that the occupant can visually recognize the virtual image object I formed by the virtual image (image) as floating above the road located outside the vehicle.

[0071] Here, the occupant's viewpoint E may be either the viewpoint of the left eye or the viewpoint of the right eye of the occupant. Alternatively, the viewpoint E may be defined as the midpoint of a line segment connecting the viewpoints of the left eye and the right eye. The position of the occupant's viewpoint E is identified based on image data acquired by the internal camera 6B, for example. The position of the occupant's viewpoint E may be updated at a predetermined cycle, or may be determined only once when the vehicle 1 is started.

[0072] When forming a 2D image (planar image) as the virtual image object I, a predetermined image is projected so as to become a virtual image at a single distance determined arbitrarily. When forming a 3D image (stereoscopic image) as the virtual image object I, a plurality of predetermined images, which may be the same or different from each other, are projected so as to become virtual images at different distances. In addition, the distance of the virtual image object I (the distance from the occupant's viewpoint E to the virtual image) can be appropriately adjusted by adjusting the optical distance (optical path length) from the image generation unit 24 to the occupant's viewpoint E (for example, by adjusting the distance between the image generation unit 24 and the concave mirror 27).

[0073] 6, when light L2a traveling in the opposite direction to the light emitted from the image generating unit 24 (hereinafter referred to as return light) enters the second polarizing plate 72 of the optical isolator 70, light L2b having only a specific directional component of the return light L2a passes through the second polarizing plate 72 and is emitted. As described above, the light L2b that can pass through the second polarizing plate 72 is light rotated 45° clockwise as viewed from the first polarizing plate 71 and Faraday element 73 side with respect to the light having only a vertical component that passes through the first polarizing plate 71 (i.e., light rotated 45° counterclockwise as viewed from the traveling direction of the return light L2a).

[0074] Next, the return light L2b emitted from the second polarizing plate 72 and incident on the Faraday rotator 75 rotates in the opposite direction to the rotation direction of the light L1b emitted from the image generating unit 24. That is, the return light L2b incident on the Faraday rotator 75 rotates 45° counterclockwise with respect to the traveling direction of the return light L2b. Therefore, the return light L2c emitted from the Faraday rotator 75 becomes light having only a horizontal component rotated 90° with respect to the light L1b having only a vertical component emitted from the image generating unit 24 and transmitted through the first polarizing plate 71.

[0075] Next, the return light L2c having only a horizontal component output from the Faraday rotator 75 enters the first polarizing plate 71. However, the return light L2c is absorbed by the first polarizing plate 71 and does not pass through the first polarizing plate 71. This is because, as described above, the return light L2c entering the first polarizing plate 71 is linearly polarized light having only a horizontal component rotated 90° with respect to the polarization direction of light that can pass through the first polarizing plate 71, that is, the light L1b having only a vertical component output from the image generating unit 24 and transmitted through the first polarizing plate 71.

[0076] 7, in the case of a HUD 20A not provided with an optical isolator 70 as in FIG. 2, when external light such as sunlight entering from outside the vehicle enters the inside of the housing 22 through the exit window 23, the external light may be reflected by the concave mirror 27 or the plane mirror 26 and irradiated in a concentrated state to the image generating unit 24. When such concentrated external light is irradiated to the image generating unit 24 (the light exit surface), far infrared rays contained in the external light may cause heat damage due to an excessive temperature rise on the light exit surface, which may deteriorate the image generating unit 24.

[0077] In contrast, the HUD 20 according to the present embodiment includes an image generating unit 24 (an example of a light source), a concave mirror 27 (an example of an optical member) that transmits or reflects the light emitted from the image generating unit 24 to magnify the light and irradiate it to the outside, and an optical isolator 70 that can transmit the light emitted from the image generating unit 24 while preventing external light from outside the vehicle from entering the image generating unit 24. In addition, in the HUD 20, the optical isolator 70 is disposed at a position between the concave mirror 27 and the windshield 18 through which the light emitted from the image generating unit 24 passes. As a result, as shown in FIG. 8, the optical isolator 70 can prevent external light from entering the image generating unit 24. Therefore, the occurrence of heat damage can be prevented. In addition, as shown in FIG. 5, the optical isolator 70 can transmit the light emitted from the image generating unit 24, so that the image generating function (light emitting function) is not reduced.

[0078] The optical isolator 70 in this embodiment has a first polarizing plate 71 that polarizes the light L1a emitted from the image generating unit 24, for example, in a vertical direction (an example of a first direction), a Faraday element 73 that outputs the light L1c obtained by rotating the light L1b polarized by the first polarizing plate 71 in a direction (an example of a second direction) 45° clockwise as viewed from the traveling direction of the light L1b from the vertical direction by the Faraday effect generated in response to the application of a magnetic field, and a second polarizing plate 72 that transmits the light L1c rotated by the Faraday element 73. The Faraday element 73 is configured to transmit the return light L2b polarized by the second polarizing plate 72, which is a return light (for example, external light) in the opposite direction to the traveling direction of the light L1a emitted from the image generating unit 24, while rotating it 45° counterclockwise as viewed from the traveling direction, and then emit it along a horizontal direction (an example of a third direction). The return light L2c having only a horizontal component is blocked by the first polarizing plate 71 and does not reach the image generating unit 24. In this way, with a simple configuration, it is possible to block external light entering the image generating unit 24 and prevent heat damage.

[0079] Moreover, the Faraday element 73 (Faraday rotator 75) includes a base layer 75A, a Faraday layer 75B provided on the base layer 75A, and a protective layer 75C provided on the Faraday layer 75B. This makes it possible to suppress deterioration of the Faraday rotator 75.

[0080] As described above, at least one of the first polarizing plate 71 and the second polarizing plate 72 may be provided with a filter for blocking at least one of ultraviolet light and infrared light, thereby broadening the band required for the Faraday element 73, i.e., reducing the wavelength dependency of the Faraday element 73.

[0081] (First Modification) FIG. 9 is a schematic diagram showing the configuration of a HUD 20B according to a first modified example of the first embodiment. The HUD 20B shown in FIG. 9 is different from the HUD 20 of the first embodiment in that the optical isolator 70 is disposed between the image generating unit 24 and the plane mirror 26. In this way, even by disposing the optical isolator 170 between the image generating unit 24 and the plane mirror 26, it is possible to block external light entering the image generating unit 24 without impairing the output function of the light emitted from the image generating unit 24. In this modified example, it is preferable to configure the first polarizing plate 171 and the second polarizing plate 172 of the optical isolator 170 as reflective polarizers rather than absorptive polarizers. By adopting the reflective polarizers, it is possible to suppress the heat rise in the HUD main body 21. In addition, compared to the optical isolator 70 of the first embodiment, the optical isolator 170 is disposed at a position closer to the image generating unit 24 (i.e., closer to the center of the HUD main body 21). Therefore, even if reflective polarizers are used for the first polarizing plate 171 and the second polarizing plate 172, the possibility of glare occurring is low.

[0082] (Second Modification) FIG. 10 is a schematic diagram showing the configuration of a HUD 20C according to a second modified example of the first embodiment. As shown in FIG. 10, the HUD 20C according to the modified example is composed of a HUD main body 21 and a combiner 19. The combiner 19 is provided inside the windshield 18 as a structure separate from the windshield 18. The combiner 19 is, for example, a transparent plastic disk, and light reflected by a plane mirror 26 and a concave mirror 27 and transmitted through an optical isolator 70 is irradiated onto the combiner 19 instead of the windshield 18. As a result, a part of the light irradiated from the HUD main body 21 to the combiner 19 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 21 as a virtual image object I formed at a predetermined distance in front of the combiner 19 (and the windshield 18). In this way, the HUD 20C equipped with the combiner 19 can also achieve the same effect as the HUD 20 of the first embodiment.

[0083] Second Embodiment FIG. 11 is a schematic diagram illustrating a vehicle lamp 300 according to the second embodiment. 11, a vehicle lamp 300 (an example of a light emitting device) includes a lamp housing 301 and a transparent cover 302 (an example of an outer lens) attached so as to cover an opening of the lamp housing 301. A light source unit 310 is provided together with an extension 304 in a lamp chamber 303 formed by the lamp housing 301 and the transparent cover 302. In addition, an electronic unit 305 is attached to the outer bottom surface of the lamp housing 301 as a lighting control unit that controls the lighting state of a light source (LED 312) mounted in the light source unit 310.

[0084] The light source unit 310 is a so-called projector-type lamp unit, and includes a unit base 311 and an LED 312 provided as a light source on the unit base 311. The light source unit 310 further includes a reflector 313 provided so as to cover the LED 312, an optical isolator 314 disposed in front of the LED 312, and a projection lens 315 disposed in front of the optical isolator 314.

[0085] Although not shown in the figures, the optical isolator 314 has a similar configuration to the optical isolator 70 of the first embodiment. That is, the optical isolator 314 has a first polarizing plate, a second polarizing plate, and a Faraday element. The Faraday element is disposed between the first polarizing plate and the second polarizing plate on the optical path of the light emitted from the LED 312.

[0086] According to the vehicle lamp 300 configured in this manner, the optical isolator 314 is disposed at a position between the LED 312 and the projection lens 315 through which the light emitted from the LED 312 passes. This prevents external light from entering the LED 312, thereby preventing the occurrence of heat damage. Furthermore, the light emitted from the LED 312 can be transmitted through the optical isolator 314 and emitted forward of the vehicle lamp 300 via the projection lens 315 and the transparent cover 302. Therefore, the light emission function of the LED 312 is not impaired.

[0087] Third embodiment Fig. 12 is a schematic diagram of a HUD 120 according to the third embodiment as viewed from the side of the vehicle 1. In the description of the third embodiment, for the sake of convenience, the description of the members having the same reference numbers as those already described in the description of the first embodiment will be omitted. As illustrated in Fig. 12, the HUD 120 includes a HUD main body 21. The HUD main body 21 has a housing 22 and an exit window 23. The HUD main body 21 has an image generating unit 24, a control unit 25, and a concave mirror 30 (an example of a reflecting unit) inside the housing 22.

[0088] The image generating unit 24 is configured to emit light for generating a predetermined image for displaying HUD information. The predetermined image includes a first image for displaying the first HUD information and a second image for displaying the second HUD information. That is, the image generating unit 24 is configured to emit a first light for generating the first image and a second light for generating the second image.

[0089] The concave mirror 30 is disposed on the optical path of the light emitted from the display device of the image generating unit 24. The concave mirror 30 reflects the light emitted from the image generating unit 24 toward the windshield 18 (for example, the front window of the vehicle 1). The concave mirror 30 has a reflective surface 31 curved concavely to form a virtual image, and reflects the light image emitted from the image generating unit 24 and formed at a predetermined magnification.

[0090] The reflecting surface 31 includes a first reflecting area 31A and a second reflecting area 31B. The first reflecting area 31A reflects the first light emitted from the image generating unit 24 for generating a first image. The second reflecting area 31B reflects the second light emitted from the image generating unit 24 for generating a second image. The image generating unit 24 includes a first image area to which the first light is emitted to be irradiated to the first reflecting area 31A, and a second image area to which the second light is emitted to be irradiated to the second reflecting area 31B. The control unit 25 controls the image generating operation of the first image area and the second image area in the image generating unit 24 so that the first light is irradiated to the first reflecting area 31A and the second light is irradiated to the second reflecting area 31B.

[0091] The light reflected by the concave mirror 30 and emitted from the exit window 23 of the HUD main body 21 is irradiated onto the windshield 18. A part of the light irradiated from the HUD main body 21 onto the windshield 18 is reflected towards the occupant's viewpoint E. As a result, the occupant recognizes the light emitted from the HUD main body 21 as a virtual image (an example of a predetermined image) formed at a predetermined distance in front of the windshield 18. In this way, the predetermined image displayed by the HUD 20 is superimposed on the real space in front of the vehicle 1 through the windshield 18, so that the occupant can visually recognize the virtual image object I formed by the predetermined image as floating above the road located outside the vehicle.

[0092] The second reflection area 31B of the reflection surface 31 of the concave mirror 30 has a second surface roughness that is rougher than the first surface roughness of the first reflection area 31A. As a result, in the virtual image object I, the virtual image of the first image formed by the light reflected by the first reflection area 31A is recognized as a virtual image having a higher image quality than the virtual image of the second image formed by the light reflected by the second reflection area 31B.

[0093] Next, a specific configuration of the concave mirror 30 according to the third embodiment will be described with reference to FIGS. 13A to 13C. FIG. 13A is a schematic diagram of the concave mirror 30 according to the third embodiment as viewed from the image generating unit 24. In FIG. 13A, the dashed line indicates the boundary between the first reflection region 31A and the second reflection region 31B. FIG. 13B is a cross-sectional view of the concave mirror 30 in FIG. 13A as viewed from the direction of the arrow along line IIIB-IIIB. FIG. 13C is a partially enlarged view showing the region IIIC in FIG. 13B. In FIG. 13C, the two-dot chain line indicates the boundary between the regions 41a, 42a on the rear surface 40a of the base member 40 and the regions 51a, 52a on the rear surface 50a of the reflective film 50, which correspond to the first reflection region 31A and the second reflection region 31B.

[0094] As illustrated in FIG. 13A, the concave mirror 30 is formed so that the first reflective area 31A and the second reflective area 31B are arranged side by side in the vertical direction of the vehicle.

[0095] The concave mirror 30 has a base member 40 and a reflective film 50 formed on the base member 40, as illustrated in FIG. 13B, for example.

[0096] The base member 40 is formed from, for example, a thermoplastic resin such as polycarbonate, glass, or the like. The base member 40 is formed so that the rear surface (the surface on which the reflective film 50 is formed) 40a has different surface roughness between the areas corresponding to the first reflection area 31A and the second reflection area 31B. Specifically, as illustrated in FIG. 13C, the rear surface 40a of the base member 40 has an area 41a corresponding to the first reflection area 31A and an area 42a corresponding to the second reflection area 31B. The rear surface 40a is formed so that the surface roughness of the area 41a is smoother than the surface roughness of the area 42a. For example, the base member 40 may be formed by injection molding a thermoplastic resin using a mold formed so that the roughness of the surface forming the area 41a of the rear surface 40a is smoother than the roughness of the surface forming the area 42a.

[0097] The reflective film 50 is formed of a metal such as aluminum. The reflective film 50 is formed such that the rear surface 50a has different surface roughness between the regions corresponding to the first reflection region 31A and the second reflection region 31B. Specifically, as illustrated in FIG. 13C, the rear surface 50a of the reflective film 50 has a region 51a forming the first reflection region 31A and a region 52a forming the second reflection region 31B. The rear surface 50a is formed such that the surface roughness of the region 51a is smoother than the surface roughness of the region 52a. Here, the rear surface 50a of the reflective film 50 forms the reflective surface 31 that reflects the light emitted from the image generating unit 24. Therefore, the surface roughness of the region 52a, i.e., the surface roughness of the second reflection region 31B, is rougher than the surface roughness of the region 51a, i.e., the surface roughness of the first reflection region 31A. For example, the reflective film 50 may be formed by evaporating a metal such as aluminum onto the base member 40. The reflective film 50 formed by vapor deposition is thin and is affected by the surface roughness of the rear surface 40a of the base member 40, so that the rear surface 50a can be formed to have different surface roughness between the regions 51a and 52a.

[0098] Fig. 14 is a schematic diagram illustrating an area 60 on the windshield 18 that is irradiated with light emitted from the HUD 120. In Fig. 14, a dashed dotted line C indicates a center line that passes through the vertical center of the windshield 18 and extends in the horizontal direction.

[0099] As illustrated in Fig. 14, when the light emitted from the HUD 120 is irradiated to an area 60 located below the center line C in the windshield 18, the concave mirror 30 is formed so that the first reflection area 31A is located below the second reflection area 31B, for example, as illustrated in Fig. 13A. As a result, as illustrated in Fig. 14, the first light reflected by the first reflection area 31A is irradiated to an area 60A of the windshield 18. Moreover, the second light reflected by the second reflection area 31B is irradiated to an area 60B located below the area 60A of the windshield 18.

[0100] As described above, the HUD 120 according to the third embodiment includes an image generating unit 24 that emits a first light for generating a first image among the predetermined images and a second light for generating a second image among the predetermined images. The HUD 120 also includes a concave mirror 30 as a reflecting mirror that reflects the first light and the second light so that the first light and the second light emitted by the image generating unit 24 are irradiated onto the windshield 18. The concave mirror 30 has a reflecting surface 31 including a first reflecting area 31A that reflects the first light and a second reflecting area 31B that reflects the second light. The first reflecting area 31A has a first surface roughness, and the second reflecting area 31B has a second surface roughness that is rougher than the first surface roughness. According to this configuration, the second reflecting area 31B has a rougher surface roughness than the first reflecting area 31A, and therefore can be formed at a lower cost than the first reflecting area 31A. On the other hand, the first reflecting area 31A has a smoother surface roughness than the second reflecting area 31B, and therefore the first image is recognized as a high-quality virtual image. Therefore, a concave mirror can be realized at low cost without significantly degrading the image quality of the virtual image.

[0101] The concave mirror 30 also has a base member 40 and a reflective film 50 formed on the base member 40. A rear surface 50a of the reflective film 50 forms the reflective surface 31. The surface roughness of the base member 40 (region 42a of the rear surface 40a) corresponding to the second reflective region 31B is rougher than the surface roughness of the base member 40 (region 41a of the rear surface 40a) corresponding to the first reflective region 31A. The surface roughness of the reflective film 50 (rear surface 50a) varies depending on the reflective region due to the influence of the surface roughness of the base member 40. According to this configuration, by changing the surface roughness of the base member 40 depending on the reflective region, it is possible to easily form a reflective film 50 having different surface roughness depending on the reflective region.

[0102] Also, as illustrated in FIG. 14, the first light reflected by the first reflection area 31A is irradiated to an area 60A above the area 60B of the windshield 18 to which the second light reflected by the second reflection area 31B is irradiated. That is, the first reflection area 31A and the second reflection area 31B are arranged side by side in the vertical direction of the vehicle so that the first light for generating the first image on the windshield 18 is irradiated to a position closer to the vertical center of the windshield 18 than the second light for generating the second image. With this configuration, the driver can recognize the virtual image of the first image at a position closer to the vertical center of the windshield 18 than the virtual image of the second image. It is highly likely that the driver directs his / her gaze to an area closer to the center in the vertical direction of the windshield 18 while the vehicle is traveling. Therefore, the driver can recognize the virtual image of the first image with high image quality while the vehicle is traveling without moving his / her gaze much. This allows the driver to accurately grasp the information indicated by the first image. Also, the driver can recognize the virtual image of the second image simply by moving his / her gaze vertically from the virtual image of the first image.

[0103] For example, the first image may show important information regarding the running of the vehicle, and the second image may show accompanying information. The important information regarding the running of the vehicle may be, for example, vehicle running information or object information present outside the vehicle. The accompanying information may be, for example, information such as a warning. In this case, the driver can accurately grasp the important information by the high-quality virtual image. In addition, the driver can check the accompanying information by simply moving his / her line of sight up and down as necessary. The accompanying information may be expressed, for example, using an image of a large mark or symbol that is not easily affected by image quality, so that the driver can check both the important information and the accompanying information without feeling uncomfortable. Therefore, compared to the case where the entire concave mirror is configured to have a smooth surface roughness, a low-cost concave mirror with almost the same information transmission function can be provided.

[0104] (Modification) In the third embodiment, the surface roughness of the base member 40 is changed according to the reflection area to form the concave mirror 30 whose reflection surface 31 has different surface roughness according to the reflection area, but the present invention is not limited to this. Fig. 15A is a schematic diagram illustrating a concave mirror 130 according to a modification of the third embodiment. Fig. 15B is a cross-sectional view of the concave mirror 130 taken along the line VB-VB and viewed from the direction of the arrows.

[0105] The modified concave mirror 130 has a reflecting surface 131 facing the image generating unit 24. As illustrated in Fig. 15A, the reflecting surface 131 is formed to include a first reflecting area 131A having a first surface roughness and a second reflecting area 131B having a second surface roughness that is rougher than the first surface roughness.

[0106] As illustrated in FIG. 15B, the concave mirror 130 includes a base member 140 and a reflective film 150 formed on the base member 140. The base member 140 includes a first base member 141 and a second base member 142. The reflective film 150 includes a first reflective film 151 formed on the first base member 141 and a second reflective film 152 formed on the second base member 142. The first reflective film 151 and the second reflective film 152 are formed of a metal such as aluminum. For example, the first reflective film 151 is formed by evaporating a metal such as aluminum on the first base member 141. The second reflective film 152 is formed by evaporating a metal such as aluminum on the second base member 142. Here, the rear surface of the reflective film 150 forms a reflective surface 131 that reflects the light emitted from the image generating unit 24. Therefore, the rear surface 151a of the first reflective film 151 forms a first reflective area 131A. The rear surface 152a of the second reflective film 152 forms the second reflective area 131B.

[0107] The first base member 141 and the second base member 142 are formed from different materials so that the second reflection area 131B has a second surface roughness that is rougher than the first surface roughness of the first reflection area 131A. For example, the first base member 141 is formed from glass, and the second base member 142 is formed from a thermoplastic resin such as polycarbonate. The surface of glass can be processed with higher precision than that of thermoplastic resin. Therefore, the surface roughness of the rear surface 142a of the second base member 142 formed from a thermoplastic resin is formed to be rougher than the surface roughness of the rear surface 141a of the first base member 141 formed from high-precision glass. The surface roughness of the rear surfaces 151a and 152a of the reflection film 150 changes due to the influence of the surfaces of the rear surfaces 141a and 142a of the base member 140. Therefore, the surface roughness of rear surface 152a, ie, the surface roughness of second reflection region 131B, is rougher than the surface roughness of rear surface 151a, ie, the surface roughness of first reflection region 131A.

[0108] In this way, the modified concave mirror 130 has the first base member 141 and the second base member 142 formed from different materials. The surface roughness of the reflective film 150 varies depending on the reflective area due to the influence of the surface of the base member 140. With this configuration, by changing the material of the base member 140 depending on the reflective area, it is possible to easily form the reflective film 150 having different surface roughness depending on the reflective area.

[0109] Furthermore, the surface roughness of the concave mirror 130 may be adjusted so that the first base member 141 and the second base member 142 each have a desired surface roughness, like the concave mirror 30 of the third embodiment.

[0110] Fourth embodiment Next, a specific configuration of concave mirror 230 according to the fourth embodiment will be described with reference to Figs. 16A and 16B. Fig. 16A is a schematic diagram of concave mirror 230 according to the fourth embodiment as viewed from image generating unit 24. Fig. 16B is a cross-sectional view of concave mirror 230 in Fig. 16A as viewed from the direction of the arrow along line VIB-VIB. In Fig. 16A, the dashed lines indicate the boundaries between first reflection area 231A, second reflection area 231B, and third reflection area 231C.

[0111] The image generating unit 24 of the fourth embodiment is configured to emit light for generating predetermined images including a first image, a second image, and a third image for displaying HUD information. That is, the image generating unit 24 is configured to emit a first light for generating the first image, a second light for generating the second image, and a third light for generating the third image.

[0112] The concave mirror 230 has a reflecting surface 231 facing the image generating unit 24. As illustrated in FIG. 16A, the reflecting surface 231 is formed to include a first reflecting area 231A, a second reflecting area 231B, and a third reflecting area 231C arranged side by side in the horizontal direction of the vehicle. The first reflecting area 231A is configured to reflect the first light emitted from the image generating unit 24. The second reflecting area 231B is configured to reflect the second light emitted from the image generating unit 24. The third reflecting area 231C is configured to reflect the third light emitted from the image generating unit 24. The control unit 25 controls the operation of the image generating unit 24 so that the first light, the second light, and the third light are irradiated onto the first reflecting area 231A, the second reflecting area 231B, and the third reflecting area 231C.

[0113] The first reflection area 231A, the second reflection area 231B, and the third reflection area 231C are formed to have different surface roughnesses. Specifically, the second reflection area 231B has a second surface roughness that is rougher than the first surface roughness of the first reflection area 231A. Also, the third reflection area 231C has a third surface roughness that is rougher than the first surface roughness of the first reflection area 231A. That is, the virtual image of the first image formed by the light reflected in the first reflection area 231A is recognized as a virtual image having a higher image quality than the virtual image of the second image formed by the light reflected in the second reflection area 231B. Also, the virtual image of the first image formed by the light reflected in the first reflection area 231A is recognized as a virtual image having a higher image quality than the virtual image of the third image formed by the light reflected in the third reflection area 231C.

[0114] 16B, the concave mirror 230 has a base member 240 and a reflective film 250 formed on the base member 240. The base member 240 is formed of, for example, a thermoplastic resin such as polycarbonate, glass, or the like. The reflective film 250 is formed of, for example, a metal such as aluminum. As in the third embodiment and its modified example, the surface roughness and / or material of the base member 240 is made different, thereby making the surface roughness of the first reflective region 231A, the second reflective region 231B, and the third reflective region 231C different.

[0115] FIG. 17 is a schematic diagram illustrating an area 160 on the windshield 18 onto which the light emitted from the HUD 120 is irradiated. As illustrated in FIG. 17, when the light emitted from the HUD 120 is irradiated onto the area 160 on the windshield 18, the concave mirror 230 is formed so that the second reflection area 231B is located to the left of the first reflection area 231A and the third reflection area 231C is located to the right of the first reflection area 231A along the horizontal direction of the vehicle, as illustrated in FIG. 16A. As a result, the first light for generating the first image reflected by the first reflection area 231A is irradiated onto the area 160A. The second light for generating the second image reflected by the second reflection area 231B is irradiated onto the area 160B located to the left of the area 160A in the horizontal direction of the windshield 18. The third light for generating the third image reflected by the third reflection area 231C is irradiated onto an area 160C located to the right of the area 160A in the horizontal direction of the windshield 18.

[0116] Thus, the reflecting surface 231 of the concave mirror 230 according to the fourth embodiment further includes a third reflecting region 231C that reflects a third light for generating a third image of the predetermined image. The third reflecting region 231C has a third surface roughness that is rougher than the first surface roughness of the first reflecting region 231A. The first reflecting region 231A, the second reflecting region 231B, and the third reflecting region 231C are arranged side by side in the horizontal direction of the vehicle with the first reflecting region 131A sandwiched between the second reflecting region 231B and the third reflecting region 231C. With this configuration, the driver can recognize the virtual images of each image while the vehicle is traveling by simply moving his / her line of sight left and right. For example, the first image may show important information regarding the traveling of the vehicle, and the second image and the third image may show accompanying information. In this case, the driver can accurately grasp the important information by the high-quality virtual image. In addition, the driver who has grasped important information regarding the traveling of the vehicle can check the accompanying information by simply moving his / her line of sight left and right as necessary. Therefore, compared to a case where the entire concave mirror is configured with smooth surface roughness, a low-cost concave mirror can be provided that has almost the same information transmission function.

[0117] The concave mirror 230 may be formed of only two reflection areas, the first reflection area 231A and the second reflection area 231B, arranged side by side in the horizontal direction. For example, the first reflection area 231A and the second reflection area 231B are arranged so that the virtual image of the first image is recognized at a position in the horizontal direction of the windshield 18 where the driver frequently looks. With this configuration, the driver can recognize the high-quality virtual image of the first image while the vehicle is running without moving his / her line of sight much. This allows the driver to accurately grasp the information indicated by the first image. Also, the driver can recognize the virtual image of the second image by simply moving his / her line of sight left and right from the virtual image of the first image.

[0118] Fifth embodiment Fig. 18 is a schematic diagram of the HUD 220 seen from the side of the vehicle 1. In the description of the fifth embodiment, for the sake of convenience, the description of the members having the same reference numbers as the members already described in the description of the first embodiment will be omitted. As illustrated in Fig. 18, the HUD 220 includes a HUD main body 21. The HUD main body 21 includes a housing 22 and an exit window 23. The HUD main body 21 includes an image generating unit 24, a control unit 25, and a reflecting unit 126 inside the housing 22.

[0119] The image generating unit 24 is configured to emit light for generating a predetermined image to be displayed toward an occupant of the vehicle 1. The predetermined image includes a first image for displaying the first HUD information and a second image for displaying the second HUD information. The image generating unit 24 is configured to emit a first light for generating the first image and a second light for generating the second image.

[0120] The reflecting unit 126 is disposed on the optical path of the light emitted from the display device of the image generating unit 24. The reflecting unit 126 reflects the light emitted from the image generating unit 24 toward the windshield 18 (for example, the front window of the vehicle 1).

[0121] The light reflected by the reflecting portion 126 and emitted from the exit window 23 of the HUD main body 21 is irradiated onto the windshield 18. A part of the light irradiated from the HUD main body 21 onto the windshield 18 is reflected toward the viewpoint E of the occupant. As a result, the occupant recognizes the light emitted from the HUD main body 21 as a virtual image (an example of a predetermined image) formed at a predetermined distance in front of the windshield 18. In this way, the image displayed by the HUD 20 is superimposed on the real space in front of the vehicle 1 through the windshield 18, so that the occupant can visually recognize the virtual image objects Ia and Ib formed by the virtual image (image) as floating above the road located outside the vehicle.

[0122] The reflecting unit 126 has a concave mirror 126A and a plane mirror 126B. The concave mirror 126A has a concavely curved reflecting surface to form a virtual image, and reflects the light image emitted from the image generating unit 24 and formed at a predetermined magnification. The plane mirror 126B has a planar reflecting surface to form a virtual image, and reflects the light image emitted from the image generating unit 24 and formed at the same magnification. The concave mirror 126A and the plane mirror 126B are arranged side by side in the vertical direction of the vehicle 1 so that the concave mirror 126A is located lower than the plane mirror 126B, as illustrated in FIG. 19. The image generating unit 24 includes a first image area where the first light irradiated to the concave mirror 126A is emitted, and a second image area where the second light irradiated to the plane mirror 126B is emitted. Control unit 25 controls the image generating operation of image generating unit 24 for the first image region and the second image region so that concave mirror 126A is irradiated with the first light and plane mirror 126B is irradiated with the second light.

[0123] For example, light (an example of a first light) emitted from a point Pa1 on the light emission surface 24A of the image generating unit 24 travels along an optical path La1, is reflected at a point Pa2 on the concave mirror 126A, travels along an optical path La2, and is emitted to the outside of the HUD 220 from the exit window 23 of the HUD main body 21. The light that has traveled along the optical path La2 is incident on a point Pa3 on the windshield 18, thereby forming a part of a virtual image object Ia (an example of a first image) formed by a predetermined image. The virtual image object Ia is formed in front of the windshield 18 at a relatively long predetermined distance (for example, about 7 to 10 m).

[0124] On the other hand, the light (an example of the second light) emitted from the point Pb1 on the light emission surface 24A of the image generating unit 24 travels along the optical path Lb1, is reflected at the point Pb2 on the plane mirror 126B, travels along the optical path Lb2, and is emitted to the outside of the HUD 220 from the exit window 23 of the HUD main body 21. The light that has traveled along the optical path Lb2 is incident on the point Pb3 of the windshield 18, thereby forming a part of the virtual image object Ib (an example of the second image) formed by a predetermined image. The virtual image object Ib is formed, for example, in front of the windshield 18 at a shorter distance (for example, about 3 to 5 m) than the virtual image object Ia.

[0125] Fig. 20 is a schematic diagram illustrating an area 260 of the windshield 18 that is irradiated with light emitted from the HUD 220. In Fig. 20, a dashed dotted line C indicates a center line that passes through the vertical center of the windshield 18 and extends in the horizontal direction.

[0126] As illustrated in FIG. 20, the light emitted from the HUD 220 is irradiated onto an area 260 located below the center line C on the windshield 18. The first light reflected by the concave mirror 126A is irradiated onto an area 260A of the windshield 18. The second light reflected by the plane mirror 126B is irradiated onto an area 260B of the windshield 18. That is, the first light reflected by the concave mirror 126A is irradiated onto a position closer to the vertical center of the windshield 18 than the second light reflected by the plane mirror 126B on the windshield 18. As a result, the virtual image object Ia is formed at a position closer to the vertical center of the windshield 18 than the virtual image object Ib.

[0127] When forming 2D images (planar images) as the virtual image objects Ia and Ib, a predetermined image is projected so as to become a virtual image at a single distance determined arbitrarily. When forming 3D images (stereoscopic images) as the virtual image objects Ia and Ib, a plurality of predetermined images, which may be the same or different from each other, are projected so as to become virtual images at different distances. In addition, the distance of the virtual image objects Ia and Ib (the distance from the occupant's viewpoint E to the virtual image) can be appropriately adjusted by adjusting the optical distance (optical path length) from the image generation unit 24 to the occupant's viewpoint E (for example, by adjusting the distance between the image generation unit 24 and the reflection unit 126).

[0128] As described above, the HUD 220 according to the fifth embodiment includes an image generating unit 24 that emits a first light for generating a first image among the predetermined images and a second light for generating a second image among the predetermined images. The HUD 220 also includes a reflecting unit 126 that reflects the first light and the second light emitted by the image generating unit 24 so that the first light and the second light are irradiated onto the windshield 18. The reflecting unit 126 includes a concave mirror 126A that reflects the first light and a plane mirror 126B that reflects the second light. The concave mirror 126A needs to form a curved, highly precise reflecting surface, which requires advanced manufacturing technology, and therefore the manufacturing cost is high, but the plane mirror 126B can be manufactured relatively inexpensively, so the cost is low. Therefore, according to the above configuration, the reflecting unit 126 is composed of the concave mirror 126A and the plane mirror 126B, so that the reflecting unit can be realized at low cost.

[0129] Moreover, the concave mirror 126A and the plane mirror 126B are arranged in line in the vertical direction of the vehicle so that the first light is irradiated to a position closer to the vertical center of the windshield 18 than the second light on the windshield 18. With this configuration, the driver can recognize the virtual image of the first image at a position closer to the vertical center of the windshield 18 than the virtual image of the second image. The driver is likely to direct his / her gaze to an area closer to the center in the vertical direction of the windshield 18 while the vehicle is traveling. Furthermore, the virtual image of the first image formed by the first light reflected by the concave mirror 126A is farther away from the driver's eye position (viewpoint) than the virtual image of the second image formed by the second light reflected by the plane mirror 126B. Therefore, the driver can recognize the virtual image of the first image while the vehicle is traveling without moving his / her gaze much and without shifting the focus of his / her eyes much. This allows the driver to instantly grasp the information indicated by the first image. Furthermore, the driver can recognize the virtual image of the second image simply by moving his / her gaze up or down from the virtual image of the first image.

[0130] For example, the first image may show important information regarding the running of the vehicle, and the second image may show accompanying information. The important information regarding the running of the vehicle may be, for example, vehicle running information or object information present outside the vehicle. The accompanying information may be, for example, information such as a warning. In this case, the driver can instantly grasp the important information while the vehicle is running without moving his / her line of sight or shifting the focus of his / her eyes much. Also, the driver can check the accompanying information by simply moving his / her line of sight up and down as necessary.

[0131] 20 shows a case where the light emitted from the HUD 220 is irradiated to the region 260 located below the center line C on the windshield 18, but the present invention is not limited to this. The light emitted by the HUD 220 may be irradiated to a region located above the center line C on the windshield 18. In this case, the concave mirror 126A and the plane mirror 126B may be arranged side by side in the vertical direction of the vehicle 1 so that the concave mirror 126A is located above the plane mirror 126B. As a result, the first light reflected by the concave mirror 126A is irradiated to a position closer to the vertical center of the windshield 18 than the second light reflected by the plane mirror 126B on the windshield 18. As a result, the virtual image object Ia is formed at a position closer to the vertical center of the windshield 18 than the virtual image object Ib.

[0132] Sixth Embodiment FIG. 21 is a schematic diagram of the HUD 220A as viewed from the side of the vehicle 1. As illustrated in FIG. 21, a HUD 220A of the sixth embodiment differs from the HUD 220 of the fifth embodiment in that a lens 28 is disposed between the image generator 24 and a plane mirror 126B.

[0133] The lens 28 is configured to change the focal length of the light emitted from the light emission surface 24A of the image generating unit 24. The lens 28 is provided at a position through which the light emitted from the light emission surface 24A of the image generating unit 24 and directed toward the plane mirror 126B passes. The lens 28 may be configured to include, for example, a drive unit, and to be able to change the distance from the image generating unit 24 by a control signal generated by the control unit 25. The movement of the lens 28 changes the focal length (apparent optical path length) of the light emitted from the image generating unit 24, and changes the distance between the windshield 18 and a predetermined image displayed by the HUD 220A.

[0134] For example, light emitted from point Pa1 on the light exit surface 24A of the image generating unit 24 travels along optical path La1, is reflected at point Pa2 on the concave mirror 126A, travels along optical path La2, and is emitted to the outside of the HUD 220A from the exit window 23 of the HUD main body 21. The light that has traveled along optical path La2 is incident on point Pa3 of the windshield 18, thereby forming a part of the virtual image object Ia formed by a predetermined image.

[0135] On the other hand, the light emitted from the point Pb1 on the light emission surface 24A of the image generating unit 24 travels along the optical path 1Lb1 after passing through the lens 28. The focal length of the light emitted from the point Pb1 changes as it passes through the lens 28. That is, the apparent optical path length of the light emitted from the point Pb1 is changed to be longer as it passes through the lens 28. The light that has traveled along the optical path 1Lb1 travels along the optical path 1Lb2 after being reflected at the point 1Pb2 on the plane mirror 126B, and is emitted to the outside of the HUD 220A from the exit window 23 of the HUD main body 21. The light that has traveled along the optical path 1Lb2 is incident on the point 1Pb3 of the windshield 18, thereby forming a part of the virtual image object 1Ib formed by a predetermined image. The virtual image object 1Ib is formed forward, away from the windshield 18 by a longer distance (for example, about 6 to 9 m) than the virtual image object Ib of the fifth embodiment. The distance of the virtual image object Ib (the distance from the windshield 18 to the virtual image) can be adjusted appropriately by adjusting the position of the lens .

[0136] As described above, the HUD 220A according to the sixth embodiment includes the lens 28 disposed on the optical path between the image generating unit 24 and the plane mirror 126B of the reflecting unit 126. The lens 28 is configured to increase the optical path length from the image generating unit 24 to the plane mirror 126B. The virtual image of the first image formed by the first light reflected by the concave mirror 126A is located at a longer distance from the driver's eye position than the virtual image of the second image formed by the second light reflected by the plane mirror 126B. For this reason, the difference in distance of the virtual image from the driver's eye position may cause the driver to feel uncomfortable. According to the above configuration, the lens 28 increases the optical path length between the image generating unit 24 and the plane mirror 126B, thereby increasing the distance from the driver's eye position to the virtual image of the second image. This reduces the driver's discomfort caused by the difference in distance of the virtual image.

[0137] Seventh embodiment FIG. 22 is a schematic diagram of the HUD 220B as viewed from the side of the vehicle 1. As illustrated in FIG. 22, the HUD 220B of the seventh embodiment differs from the HUD 220 of the fifth embodiment in that the reflector 226 includes a concave mirror 226A and two plane mirrors 226B and 226C. In addition, since the position of the plane mirror 226C in the front-to-rear direction of the vehicle 1 is the same as the position of the plane mirror 226B, it is not shown in Fig. 22 due to overlap with the plane mirror 226B. When viewed from the side of the vehicle 1, the optical paths and virtual image objects, etc. related to the plane mirror 226C are formed in the same manner as the optical paths and virtual image objects, etc. related to the plane mirror 226B, so they are not shown in the figures and only the reference numbers are shown in parentheses.

[0138] The reflecting unit 226 has a concave mirror 226A, a plane mirror 226B, and a plane mirror 226C. The concave mirror 226A has a concavely curved reflecting surface to form a virtual image, and reflects the light image emitted from the image generating unit 224 and formed at a predetermined magnification. The plane mirrors 226B and 226C have planar reflecting surfaces to form a virtual image, and reflect the light image emitted from the image generating unit 224 and formed at the same magnification. The concave mirror 226A and the plane mirrors 226B and 226C are arranged side by side in the horizontal direction of the vehicle 1, with the concave mirror 226A sandwiched between the plane mirror 226B and the plane mirror 226C, as illustrated in FIG. 23.

[0139] Image generating section 224 includes a first image area into which the first light is irradiated onto concave mirror 226A, a second image area into which the second light is irradiated onto plane mirror 226B, and a third image area into which the third light is irradiated onto plane mirror 226C. Control section 225 controls the image generating operation of image generating section 224 for the first image area, the second image area, and the third image area so that concave mirror 226A is irradiated with the first light, plane mirror 226B is irradiated with the second light, and plane mirror 226C is irradiated with the third light.

[0140] For example, light (an example of a first light) emitted from a point 2Pa1 on the light emission surface 24A of the image generating unit 224 travels along an optical path 2La1, is reflected at a point 2Pa2 on the concave mirror 226A, travels along an optical path 2La2, and is emitted to the outside of the HUD 220B from the exit window 23 of the HUD main body 21. The light that has traveled along the optical path 2La2 is incident on a point 2Pa3 on the windshield 18, thereby forming a part of a virtual image object 2Ia (an example of a first image) formed by a predetermined image. The virtual image object 2Ia is formed in front of the windshield 18 at a relatively long predetermined distance (for example, about 7 to 10 m).

[0141] On the other hand, light (an example of a second light) emitted from a point 2Pb1 on the light emission surface 24A of the image generating unit 224 travels along an optical path 2Lb1, is reflected at a point 2Pb2 on the plane mirror 226B, travels along an optical path 2Lb2, and is emitted to the outside of the HUD 220B from the exit window 23 of the HUD main body 21. The light that has traveled along the optical path 2Lb2 is incident on a point 2Pb3 on the windshield 18, thereby forming a part of a virtual image object 2Ib (an example of a second image) formed by a predetermined image. The virtual image object 2Ib is formed, for example, in front of the windshield 18 at a shorter distance (for example, about 3 to 5 m) than the virtual image object 2Ia.

[0142] Light (an example of a third light) emitted from a point 2Pc1 on the light emission surface 24A of the image generating unit 224 travels along an optical path 2Lc1, is reflected at a point 2Pc2 on the plane mirror 226C, travels along an optical path 2Lc2, and is emitted to the outside of the HUD 220B from the emission window 23 of the HUD main body 21. The light that has traveled along the optical path 2Lc2 is incident on a point 2Pc3 on the windshield 18, thereby forming a part of a virtual image object 2Ic (an example of a third image) formed by a predetermined image. The virtual image object 2Ic is formed, for example, in front of the virtual image object 2Ib and at a distance substantially equal to that of the virtual image object 2Ib.

[0143] FIG. 24 is a schematic diagram illustrating an area 360 on the windshield 18 that is irradiated with light emitted from the HUD 220B. As illustrated in FIG. 24, the first light for generating the first image reflected by the concave mirror 226A is irradiated to the region 360A. The second light for generating the second image reflected by the plane mirror 226B is irradiated to the region 360B located to the left of the region 360A in the horizontal direction of the windshield 18. The third light for generating the third image reflected by the plane mirror 226C is irradiated to the region 360C located to the right of the region 360A in the horizontal direction of the windshield 18. As a result, the virtual image object 2Ia is formed in a state where it is sandwiched between the virtual image object 2Ib and the virtual image object 2Ic along the horizontal direction of the vehicle 1.

[0144] As described above, in the HUD 220B according to the seventh embodiment, the concave mirror 226A, the plane mirror 226B, and the plane mirror 226C are arranged side by side in the horizontal direction of the vehicle 1, with the concave mirror 226A sandwiched between the plane mirror 226B and the plane mirror 226C. This allows the driver to recognize the virtual image of the first image while the vehicle is traveling, without shifting the focus of the eyes much. This allows the driver to instantly grasp the information indicated by the first image. In addition, the driver can grasp the virtual image of the second image and the virtual image of the third image by simply moving the line of sight left and right while the vehicle is traveling.

[0145] Eighth embodiment FIG. 25 is a schematic diagram of the HUD 220C as viewed from the side of the vehicle 1. As illustrated in FIG. 25, the HUD 220C of the eighth embodiment differs from the HUD 220B of the seventh embodiment in that a lens 80 is disposed between the image generator 224 and the plane mirrors 226B and 226C.

[0146] The lens 80 is configured to change the focal length of the light emitted from the light emission surface 24A of the image generating unit 224. The lens 80 is provided at a position through which the light emitted from the light emission surface 24A of the image generating unit 224 and directed toward the plane mirrors 226B and 226C passes. The lens 80 has a first lens 81 and a second lens 82. The first lens 81 is disposed between the image generating unit 224 and the plane mirror 226B. The second lens 82 is disposed between the image generating unit 224 and the plane mirror 226C. Since the second lens 82 is located at the same position as the first lens 81 in the longitudinal direction of the vehicle 1, it is not shown in FIG. 25 due to overlap with the first lens 81.

[0147] Lens 80 may include, for example, a drive unit, and may be configured so that the distance from image generator 224 can be changed by a control signal generated by controller 225. Movement of lens 80 changes the focal length (apparent optical path length) of the light emitted from image generator 224, and changes the distance between windshield 18 and a predetermined image displayed by HUD 220C.

[0148] For example, light emitted from a point 3Pa1 on the light emission surface 24A of the image generating unit 224 travels along an optical path 3La1, is reflected at a point 3Pa2 on the concave mirror 226A, travels along an optical path 3La2, and is emitted to the outside of the HUD 220C from the exit window 23 of the HUD main body 21. The light that has traveled along the optical path 3La2 is incident on a point 3Pa3 on the windshield 18, thereby forming a part of a virtual image object 3Ia formed by a predetermined image. The virtual image object 3Ia is formed in front of the windshield 18 at a relatively long predetermined distance (for example, about 7 to 10 m).

[0149] On the other hand, the light emitted from the point 3Pb1 on the light emission surface 24A of the image generating unit 224 travels along the optical path 3Lb1 after passing through the first lens 81. The focal length of the light emitted from the point 3Pb1 changes as it passes through the first lens 81. That is, the apparent optical path length of the light emitted from the point 3Pb1 is lengthened as it passes through the first lens 81. The light that has traveled along the optical path 3Lb1 travels along the optical path 3Lb2 after being reflected by the point 3Pb2 on the plane mirror 226B, and is emitted to the outside of the HUD 220C from the exit window 23 of the HUD main body 21. The light that has traveled along the optical path 3Lb2 is incident on the point 3Pb3 of the windshield 18, thereby forming a part of the virtual image object 3Ib formed by a predetermined image. The virtual image object 3Ib is formed in front of the windshield 18 at a longer distance (for example, about 6 to 9 m) than the virtual image object 2Ib of the seventh embodiment. The distance of the virtual image object 3Ib (the distance from the windshield 18 to the virtual image) can be appropriately adjusted by adjusting the position of the first lens 81.

[0150] The light emitted from the point 3Pc1 on the light emission surface 24A of the image generating unit 224 travels along the optical path 3Lc1 after passing through the second lens 82. The focal length of the light emitted from the point 3Pc1 changes as it passes through the second lens 82. That is, the apparent optical path length of the light emitted from the point 3Pc1 is lengthened as it passes through the second lens 82. The light that has traveled along the optical path 3Lc1 travels along the optical path 3Lc2 after being reflected by the point 3Pc2 on the plane mirror 226C, and is emitted to the outside of the HUD 220C from the exit window 23 of the HUD main body 21. The light that has traveled along the optical path 3Lc2 is incident on the point 3Pc3 of the windshield 18, thereby forming a part of the virtual image object 3Ic formed by a predetermined image. The virtual image object 3Ic is formed in front of the windshield 18 at a longer distance (for example, about 6 to 9 m) than the virtual image object 2Ic of the seventh embodiment. The distance of the virtual image object 3Ic (the distance from the windshield 18 to the virtual image) can be appropriately adjusted by adjusting the position of the second lens 82.

[0151] As described above, the HUD 220C according to the eighth embodiment includes the first lens 81 arranged on the optical path between the image generating unit 224 and the plane mirror 226B of the reflecting unit 226. The HUD 220C also includes the second lens 82 arranged on the optical path between the image generating unit 224 and the plane mirror 226C of the reflecting unit 226. The first lens 81 is configured to increase the optical path length from the image generating unit 224 to the plane mirror 226B. The second lens 82 is configured to increase the optical path length from the image generating unit 224 to the plane mirror 226C. The virtual image of the first image formed by the first light reflected by the concave mirror 226A is located at a longer distance from the position of the driver's eyes than the virtual image of the second image formed by the second light reflected by the plane mirror 226B. The virtual image of the first image formed by the first light reflected by the concave mirror 226A is located at a longer distance from the position of the driver's eyes than the virtual image of the third image formed by the third light reflected by the plane mirror 226C. Therefore, the difference in distance of the virtual image from the driver's eye position may give the driver a sense of discomfort. According to the above configuration, the first lens 81 lengthens the optical path length between the image generator 224 and the plane mirror 226B, thereby making it possible to lengthen the distance from the driver's eye position to the virtual image of the second image. In addition, the second lens 82 lengthens the optical path length between the image generator 224 and the plane mirror 226C, thereby making it possible to lengthen the distance from the driver's eye position to the virtual image of the third image. This makes it possible to reduce the sense of discomfort felt by the driver due to the difference in distance of the virtual images.

[0152] Ninth embodiment Fig. 26 is a schematic diagram of the HUD 320 seen from the side of the vehicle 1. In the description of the ninth embodiment, for convenience, the description of the members having the same reference numbers as the members already described in the description of the first embodiment will be omitted. As shown in Fig. 26, the HUD 320 includes a HUD main body 21. The HUD main body 21 has a housing 22 and an exit window 23. The HUD main body 21 has an image generating unit 24, a control unit 25, and a concave mirror 27 (an example of a reflecting unit) inside the housing 22.

[0153] The image generating unit 24 emits light for generating an image from a light emitting surface (display device surface) 124 toward the outside. The light emitting surface 124 of the image generating unit 24 is provided with a first light emitting surface (an example of a first region) 124A and a second light emitting surface (an example of a second region) 124B which is an emitting surface other than the first light emitting surface 124A. The first light emitting surface 124A is an emitting surface that emits light for generating a first image which is a part of a predetermined image. The second light emitting surface 124B is an emitting surface that emits light for generating a second image which is a part of the predetermined image and is different from the first image. The first light emitting surface 124A and the second light emitting surface 124B will be described later with reference to FIG. 28.

[0154] The concave mirror 27 is disposed on the optical path of the light emitted from the image generating unit 24. The concave mirror 27 is configured to reflect the light emitted from the image generating unit 24 toward the windshield 18 (for example, the front window of the vehicle 1). The concave mirror 27 has a reflective surface that is concavely curved to form a predetermined image, and reflects the light image emitted from the image generating unit 24 and focused thereon at a predetermined magnification. The concave mirror 27 may have a drive mechanism (not shown) and be configured to rotate the orientation of the concave mirror 27 based on a control signal transmitted from the control unit 25.

[0155] The light emitted from the light emission surface 124 of the image generating unit 24 is reflected by the concave mirror 27 and emitted from the emission window 23 of the HUD main body 21. The light emitted from the emission window 23 of the HUD main body 21 is irradiated onto the windshield 18. A part of the light irradiated from the emission window 23 onto the windshield 18 is reflected toward the viewpoint E of the occupant. As a result, the occupant recognizes the light emitted from the HUD main body 21 as a virtual image (predetermined image) formed at a predetermined distance in front of the windshield 18. In this way, the image displayed by the HUD 20 is superimposed on the real space in front of the vehicle 1 through the windshield 18, so that the occupant can visually recognize the virtual image object I formed by the predetermined image as floating above the road located outside the vehicle.

[0156] Incidentally, since the light emitted from the light exit surface 124 of the image generating unit 24 is reflected by the concave mirror 27, the virtual image object I recognized by the occupant as a predetermined image is distorted due to the reflection by the concave mirror 27. Therefore, in order to allow the occupant to accurately recognize the information of the virtual image object I, it is desirable to perform, for example, a correction process for the distortion of the generated virtual image object I.

[0157] Next, the distortion occurring in the virtual image object and the process for correcting the distortion (correction by image warping) will be described with reference to FIGS. 27A, 27B, 28 and 29. FIG.

[0158] Fig. 27A shows an example of an image on a light exit surface 424 of an image generating unit, i.e., an image (hereinafter, also referred to as an exit surface image) 431 generated by light before being reflected by a concave mirror, in an image generated by light emitted from an image generating unit of a HUD according to a comparative example. Fig. 27B shows a virtual image object X that is recognized by an occupant as a predetermined image after the exit surface image 431 shown in Fig. 27A is reflected by a concave mirror. Note that, in the image of this example, information indicating the traveling speed (50 km / h) of the vehicle is displayed.

[0159] As shown in Fig. 27A, when the exit surface image 431 at the light exit surface 424 of the image generating unit according to the comparative example is a normal image, for example, an image that has not been subjected to a predetermined correction process for distortion caused by reflection by a concave mirror, the virtual image object X generated by the light reflected by the concave mirror is displayed as an image with a distorted shape, as shown in Fig. 27B. In this example, the virtual image object X is displayed as an image with an expanded upper side and a contracted lower side.

[0160] In contrast, in the image generating unit 24 of the HUD 320 according to the ninth embodiment, in order to correct the image distortion caused by reflection on the concave mirror 27, an inverse correction process (also called a correction process by warping) is applied to the exit surface image in advance.

[0161] Fig. 28 shows an example of exit surface images 331, 332 generated by light emitted from the image generating unit 24 of the HUD 320. Fig. 29 shows the exit surface images 331, 332 shown in Fig. 28 reflected by the concave mirror 27 and displayed as virtual object in front of the vehicle. As shown in Fig. 28, the light exit surface 124 of the image generating unit 24 is formed in a rectangular shape, and a first light exit surface 124A and a second light exit surface 124B are provided. An exit surface image 331 is generated by the light emitted from the first light exit surface 124A, and an exit surface image 332 is generated by the light emitted from the second light exit surface 124B. In the exit surface image 331 of this example, a speed image notifying that the current driving speed is 50km / h and an attention calling image (angle bracket pattern) that calls the attention of the occupant are displayed. In addition, in the exit surface image 332, an attention calling image (angle bracket pattern) that calls the attention of the occupant is displayed.

[0162] The first light exit surface 124A of the rectangular light exit surface 124 is formed as, for example, an annular sector-shaped exit surface. The annular sector-shaped first light exit surface 124A forms a rectangular maximum display range 351 in which the virtual image object Ia shown in FIG. 29 is displayed. That is, it is preferable that the first light exit surface 124A is formed so as to occupy an area in the light exit surface 124 where the annular sector spreads to the maximum extent. The second light exit surface 124B of the rectangular light exit surface 124 is formed as an exit surface of an area other than the first light exit surface 124A. That is, the second light exit surface 124B forms a rectangular display range 352 in which the virtual image object Ib shown in FIG. 29 is displayed in an area other than the maximum display range 351 in which the virtual image object Ia is displayed. The second light exit surface 124B of this example is formed in an area closer to the inner arc 342 than the outer arc 341 in the annular sector-shaped first light exit surface 124A. Specifically, the second light emitting surface 124B is formed on both the left and right sides of a lower region having a narrower left-right width in the first light emitting surface 124A. Thus, in the light emitting surface 124, the first light emitting surface 124A is formed larger than the second light emitting surface 124B.

[0163] In order to correct distortion caused by reflection from the concave mirror 27, the exit surface image 331 of the first light exit surface 124A and the exit surface image 332 of the second light exit surface 124B are subjected to inverse correction (warping) in which the images are distorted in advance in the opposite direction by the amount of distortion caused by reflection from the concave mirror 27. In this example, the exit surface images 331 and 332 are subjected to correction to extend the upper side of the image and to shrink the lower side.

[0164] 27B, the amount of distortion caused in the virtual image object I due to reflection at the concave mirror 27 is smaller toward the center of the virtual image object I and is larger away from the center. Therefore, the amount of correction by warping applied to the exit surface images 331, 332 that are the original images of the virtual image object I differs depending on the positions of the exit surface images 331, 332 in response to the magnitude of the amount of distortion due to the part of the virtual image object I. For example, the amount of correction of the exit surface image at a position corresponding to the center of the virtual image object I is relatively small, and the amount of correction of the exit surface image at a position corresponding to a part away from the center is relatively large.

[0165] In this example, the exit surface image 332 of the second light exit surface 124B is displayed in an area close to an inner arc 342 of the first light exit surface 124A, which is a large annular sector formed in the center of the light exit surface 124. The exit surface image 332 is an image displayed in an area away from the center of the light exit surface 124. The exit surface image 331 of the first light exit surface 124A is an image at a position corresponding to the center of the virtual image object I. Moreover, the exit surface image 332 of the second light exit surface 124B is an image at a position corresponding to a portion away from the center of the virtual image object I. For this reason, the image generating unit 24 generates the exit surface images 331, 332 on the light exit surface 124 so that a correction coefficient for correcting the distortion caused by the light constituting the exit surface image 332, which is the original image of the virtual image object Ib, being reflected by the concave mirror 27, is larger than a correction coefficient for correcting the distortion caused by the light constituting the exit surface image 331, which is the original image of the virtual image object Ia, being reflected by the concave mirror 27. That is, when correcting the distortion caused in the virtual image object I, the correction amount of the exit surface image 332 displayed on the second light exit surface 124B is larger than the correction amount of the exit surface image 331 (average correction amount of the entire exit surface image 331).

[0166] As described above, the exit surface images 331 and 332 are subjected to an inverse correction process in which the images are distorted in the opposite direction in advance by an amount equal to the amount of distortion caused by reflection on the concave mirror 27. Therefore, when the light generating the exit surface images 331 and 332 is reflected on the concave mirror 27, the images are visually recognized as a virtual image object I (Ia, Ib) without distortion, as shown in Fig. 29. The virtual image object Ia is an image generated by the exit surface image 331 of the first light exit surface 124A. The virtual image object Ib is an image generated by the exit surface image 332 of the second light exit surface 124B.

[0167] The virtual image object Ia and the virtual image object Ib are configured so that the position where the virtual image object Ia is recognized and the position where the virtual image object Ib is recognized are substantially the same in front of the vehicle 1. That is, the distance from the windshield 18 to the virtual image object Ia and the distance from the windshield 18 to the virtual image object Ib are configured so as to be substantially the same.

[0168] The virtual image object Ib is displayed around the virtual image object Ia so as to be lined up with the virtual image object Ia. In this example, the virtual image object Ib is displayed on the left and right of the virtual image object Ia as seen by the occupant of the vehicle 1. The information displayed by the virtual image object Ia and the information displayed by the virtual image object Ib may be configured to be mutually associated information. As an example, the virtual image object Ia displays speed information (50 km / h) notifying the driving speed and attention calling information (angle bracket pattern) calling attention to the driving speed. In addition, the virtual image object Ib displays attention calling information (angle bracket pattern) calling attention to the notification content of the virtual image object Ia. The angle bracket pattern of the virtual image object Ib is displayed side by side to the left or right of the angle bracket pattern of the virtual image object Ia so as to form a continuous angle bracket pattern. The display range of the image viewed as the virtual image object I is the image range obtained by adding together the virtual image object Ia (first image) formed by the light emitted from the first light emitting surface 124A and the virtual image object Ib (second image) formed by the light emitted from the second light emitting surface 124B.

[0169] As described above, the HUD 320 according to this embodiment includes the image generating unit 24 that emits light for generating a virtual image object I (a predetermined image), and the concave mirror 27 (an example of a reflecting unit) that reflects the light emitted by the image generating unit 24 so that the light emitted by the image generating unit 24 is irradiated onto the windshield 18. In addition, in the light emitting surface 124 of the image generating unit 24, a region capable of forming a rectangular maximum display range 351 in which a virtual image object Ia (an example of a first image) that is a part of the virtual image object I is displayed is set as a first light emitting surface 124A (an example of a first region), and a region other than the first light emitting surface 124A is set as a second light emitting surface 124B (an example of a second region), and a virtual image object Ib (an example of a second image) different from the virtual image object Ia is displayed by light emitted from the second light emitting surface 124B outside the maximum display range 351 in which the virtual image object Ia can be displayed by light emitted from the first light emitting surface 124A. According to this configuration, by providing the second light emitting surface 124B in addition to the first light emitting surface 124A within the light emitting surface 124 of the image generating unit 24, it is possible to provide a display range 352 in which the virtual image object Ib is displayed in an area outside the rectangular maximum display range 351 in which the virtual image object Ia is displayed. Therefore, it is possible to widen the display range of the virtual image (image) compared to a conventional HUD in which the image generating unit has only a single light emitting surface (see FIG. 27A).

[0170] In the HUD 320 according to the present embodiment, the light exit surface 124 is formed in a rectangular shape, the first light exit surface 124A is formed as an annular sector area of ​​the rectangular light exit surface 124, and the second light exit surface 124B is formed in an area of ​​the light exit surface 124 closer to the inner arc than the outer arc of the annular sector first light exit surface 124A. With this configuration, the portion of the rectangular light exit surface 124 other than the annular sector first light exit surface 124A, specifically, the left and right sides of the lower area having a small left-right width in the annular sector first light exit surface 124A, can be efficiently used as the area where the second light exit surface 124B is formed. Therefore, the display range of the virtual image (image) can be expanded while suppressing the increase in size of the expensive light exit surface 124.

[0171] In addition, in the HUD 320 according to this embodiment, a correction coefficient for correcting the distortion of the virtual image object Ib caused by the light constituting the original image (exit surface image 332) of the virtual image object Ib generated by the image generating unit 24 being reflected by the concave mirror 27 in the image generating unit 24 is configured to be larger than a correction coefficient for correcting the distortion of the virtual image object Ia caused by the light constituting the original image (exit surface image 331) of the virtual image object Ia generated by the image generating unit 24 being reflected by the concave mirror 27 in the image generating unit 24. Since the second light exit surface 124B is formed closer to the outer edge portion side of the light exit surface 124 of the image generating unit 24 than the first light exit surface 124A, the virtual image object Ib is more likely to be distorted by reflection at the concave mirror 27 than the virtual image object Ia. Therefore, by making the correction coefficient of the virtual image object Ib displayed on the second light emitting surface 124B larger than the correction coefficient of the virtual image object Ia displayed on the first light emitting surface 124A, the distortion of the virtual image object Ib with a large amount of distortion can be appropriately corrected.

[0172] Furthermore, according to the HUD 320, virtual image objects Ib are displayed on the left and right of the virtual image object Ia, and the contents of information displayed by the images of the virtual image objects Ia and Ib may be associated with each other. For example, attention-calling information (angle brackets) displayed as the virtual image object Ia and attention-calling information (angle brackets) displayed as the virtual image object Ib may be displayed in sequence. In this way, various types of information can be provided to the occupant by cooperation between the virtual image object Ia and the virtual image object Ib.

[0173] In addition, a third light exit surface may be provided at each of the upper left and right corners of the light exit surface 124 in FIG. 28 (not shown). The correction coefficient of the third light exit surface is preferably larger than the correction coefficient of the first light exit surface 124A, similar to the second light exit surface 124B. A virtual image object is displayed below each of the lower ends of the virtual image object Ia in FIG. 29 by the light emitted from the third light exit surface. In this way, the display range of the virtual image (image) can be further expanded by effectively utilizing the area of ​​the light exit surface 124 other than the first light exit surface 124A and the second light exit surface 124B as the third light exit surface.

[0174] (Modification) FIG. 30 is a schematic diagram showing the configuration of a HUD 320A according to a modified example. As shown in FIG. 30, a HUD 320A according to a modified example is composed of a HUD main body 21 and a combiner 19. The combiner 19 is provided inside the windshield 18 as a structure separate from the windshield 18. The combiner 19 is, for example, a transparent plastic disk, and light emitted from a light emitting surface 124 and reflected by a concave mirror 27 is irradiated onto the combiner 19 instead of the windshield 18. As a result, a part of the light irradiated from the HUD main body 21 onto the combiner 19 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 21 as a virtual image object I formed at a predetermined distance in front of the combiner 19 (and the windshield 18). The HUD 320A equipped with such a combiner 19 can also achieve the same effects as the HUD 20 described above.

[0175] Although the embodiment of the present disclosure has been described above, it goes without saying that the technical scope of the present invention 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 invention should be determined based on the scope of the invention described in the claims and its equivalents.

[0176] The optical isolator 70 as described in the first embodiment may be provided in a light emitting device as a projector configured to display a predetermined image on an object such as an outdoor wall. That is, in the projector, for example, the optical isolator may be disposed at a position where light from the light source passes between the light source and an optical member (such as a lens) or between the optical member and an image display object. This makes it possible to provide a projector that can prevent heat damage caused by external light entering the light source without deteriorating the light emitting function.

[0177] In the above third and fourth embodiments, the first and second images (or the first, second and third images) are displayed simultaneously, but the present invention is not limited to this. For example, only one image may be displayed depending on the HUD information to be displayed.

[0178] In the third embodiment, the base member 40 of the concave mirror 30 is formed from a single (monolithic) member, but this is not limited thereto. For example, the base member may be formed by integrating a plurality of base members corresponding to a plurality of reflective areas with or without gaps. The reflective film 50 may be formed on the plurality of base members collectively, or may be formed on each base member.

[0179] In the modification of the third embodiment, the concave mirror 130 is integrated with the first base member 141 and the second base member 142 in contact with each other, but this is not limited thereto. For example, the first base member 141 and the second base member 142 may be integrated adjacent to each other with a gap therebetween. When forming a concave mirror by integrating a plurality of base members with gaps therebetween, the operation of the image generating unit 24 may be controlled so that light is not irradiated onto the portions corresponding to the gaps.

[0180] In the above third and fourth embodiments, the reflecting portion is a concave mirror 30, 130, 230, but is not limited thereto. For example, the reflecting portion may be a flat mirror having a reflecting surface including a plurality of reflecting regions with different surface roughnesses. This allows the reflecting portion to be realized at low cost without significantly degrading the image quality of the virtual image.

[0181] In the third and fourth embodiments, the concave mirror 30, 130, 230 is composed of the base member 40, 140, 240 and the reflective film 50, 150, 250, but is not limited thereto. For example, a top coat for corrosion prevention may be formed on the reflective film. The top coat is formed of, for example, a transparent resin, and the light emitted from the image generating unit 24 passes through the top coat and is reflected by the reflective film. That is, since the rear surface of the reflective film forms the reflective surface of the concave mirror, the surface roughness of the rear surface of the top coat may be uniform. The surface roughness of the rear surface of the top coat (the surface irradiated with the light emitted from the image generating unit 24) may be changed by forming the top coat as a thin film so as to be influenced by the surface of the reflective film.

[0182] In the third and fourth embodiments, the base members 40, 140, 240 of the concave mirrors 30, 130, 230 have different surface roughnesses or materials to form the reflecting surfaces 31, 131, 231 having different surface roughnesses, but the present invention is not limited to this. For example, the base members 40, 140, 240 may have the same surface roughness or be made of the same material, and the reflecting films 50, 150, 250 may have different surface roughnesses or materials to form reflecting surfaces having different surface roughnesses.

[0183] In the third and fourth embodiments, the concave mirror 30, 130, 230 is formed of a reflective area divided vertically or horizontally into two or three, but is not limited to this. The shape of the divided reflective area may be determined according to the position or area of ​​the windshield 18 that the driver frequently looks at.

[0184] In the third and fourth embodiments described above, the concave mirror 30, 130, 230 reflects the light emitted from the image generating unit 24 toward the windshield 18, but this is not limited to the above. The concave mirror 30, 130, 230 may reflect the light toward a combiner provided inside the windshield 18.

[0185] In the third and fourth embodiments, the light that forms the predetermined images including the first image, the second image, and the third image is emitted through one display device of the image generating unit 24, but is not limited to this. The image generating unit 24 may have a first display device that emits light that forms the first image, a second display device that emits light that forms the second image, and a third display device that emits light that forms the third image. In this case, the light source and the optical component are provided corresponding to each display device.

[0186] In the above fourth embodiment, the case where the light emitted by the HUD 120 is irradiated to an area of ​​the windshield 18 located below the center line C has been described, but the present invention is not limited to this. When the light emitted by the HUD 120 is irradiated to an area of ​​the windshield 18 located above the center line C, the concave mirror 30 may be formed, for example, so that the first reflection area 31A is disposed below the second reflection area 31B. In this case, the first light reflected by the first reflection area 31A is irradiated to an area on the windshield 18 located above an area irradiated with the second light reflected by the second reflection area 31B.

[0187] In the fifth to eighth embodiments, the image generating unit 24 may be configured to generate the second image so that its size is larger than that of the first image. The image generating unit 224 may be configured to generate the second image and the third image so that their sizes are larger than that of the first image. The concave mirrors 126A and 226A reflect the first light so that the first image is enlarged, whereas the plane mirrors 126B and 226B reflect the second light while the size of the second image remains unchanged. The plane mirrors 126C and 226C also reflect the third light while the size of the third image remains unchanged. Therefore, the size of the virtual image of the first image is larger than that of the virtual image of the second image. The size of the virtual image of the first image is larger than that of the virtual image of the third image. This difference in size of the virtual images may give the driver a sense of incongruity. According to the above configuration, the size of the virtual image of the second image (and the third image) is increased, and the sense of incongruity of the driver due to the difference in size of the virtual images can be reduced.

[0188] In the fifth to eighth embodiments, the light that forms the predetermined images including the first image, the second image, and the third image is emitted through one display device of the image generating unit 24, 224, but the present invention is not limited to this. The image generating unit 24 may include a first generating unit that generates the first image and a second generating unit that generates the second image. The image generating unit 224 may include a first generating unit that generates the first image, a second generating unit that generates the second image, and a third generating unit that generates the third image. A light source and an optical component are provided corresponding to each generating unit. In this case, the first image may be a color image, and the second image (and the third image) may be a monochrome image. According to this configuration, since the second image is a monochrome image, the second generating unit (and the third generating unit) can be realized at low cost, and as a result, the image generating unit can be realized at low cost.

[0189] In the above fifth to eighth embodiments, the first and second images (or the first, second and third images) are displayed simultaneously, but the present invention is not limited to this. For example, only one image may be displayed depending on the HUD information to be displayed.

[0190] Furthermore, the arrangement direction and number of the concave mirrors and plane mirrors constituting the reflecting portion are not limited to the vertical or horizontal arrangement and two or three arrangements in the above embodiment.

[0191] In the fifth to eighth embodiments, the reflecting units 126, 226 reflect the light emitted from the image generating units 24, 224 toward the windshield 18, but this is not limited to the above. The reflecting units 126, 226 may also reflect the light toward a combiner provided inside the windshield 18.

[0192] In the sixth and eighth embodiments, one or two lenses 28, 80 are used as the optical element disposed between the image generating unit 24, 224 and the plane mirror 126B, 226B, 226C, but this is not limited thereto. A mirror may be used as the optical element instead of or in addition to the lens. For example, multiple plane mirrors may be disposed between the image generating unit 24, 224 and the plane mirror 126B, 226B, 226C.

[0193] In the above first to ninth embodiments, the driving modes of the vehicle have been described as including the fully automated driving mode, the advanced driving assistance mode, the driving assistance mode, and the manual driving mode, but the driving modes of the vehicle should not be limited to these four modes. The driving modes of the vehicle may include at least one of these four modes. For example, the driving modes of the vehicle may be executable in only one of them.

[0194] Furthermore, the classification and display form of the vehicle driving mode may be appropriately changed in accordance with the laws or regulations related to autonomous driving in each country. Similarly, the definitions of the "fully autonomous driving mode", the "advanced driving assistance mode", and the "driving assistance mode" described in the explanations of the first to ninth embodiments are merely examples, and these definitions may be appropriately changed in accordance with the laws or regulations related to autonomous driving in each country.

[0195] This application is based on Japanese Patent Application No. 2019-179484 filed on September 30, 2019, Japanese Patent Application No. 2019-197510 filed on October 30, 2019, Japanese Patent Application No. 2019-197511 filed on October 30, 2019, and Japanese Patent Application No. 2019-211328 filed on November 22, 2019, the contents of which are incorporated herein by reference.

Claims

1. A head-up display provided in a vehicle, A light source; an optical member that transmits or reflects light emitted from the light source to expand the light and irradiate it to the outside; a light emitting device including an optical isolator capable of transmitting the light while preventing external light from entering the light source; a housing in which the light emitting device is housed and which has an exit window formed therein through which the light expanded by the optical member passes; Equipped with The light emitting device is configured to display a predetermined image toward an occupant of the vehicle, The optical member transmits or reflects the light emitted by the light source so that the light is irradiated onto a windshield or a combiner, A head-up display, wherein the optical isolator is disposed at a position between the optical member and the exit window through which the light passes.

2. The optical isolator comprises: a first polarizer for polarizing the light in a first direction; a Faraday element that transmits the light polarized by the first polarizer while rotating the light polarized by the first polarizer at a predetermined rotation angle from the first direction by a Faraday effect generated in response to application of a magnetic field, and outputs the light along a second direction; a second polarizer that transmits the light along the second direction; and having 2. The head-up display of claim 1, wherein the Faraday element transmits the external light polarized along the second direction by the second polarizer while rotating it at the specified rotation angle, and then emits it along a third direction different from the first direction and the second direction.

3. The head-up display according to claim 2 , wherein the Faraday element includes a base layer, a Faraday layer provided on the base layer, and a protective layer provided on the Faraday layer.

4. The head-up display according to claim 2 or 3, wherein the Faraday element is at least partially covered by a housing made of a magnetic material.

5. 5. The head-up display according to claim 2, wherein at least one of the first polarizer and the second polarizer is provided with a filter for blocking at least one of ultraviolet light and infrared light.

Images