Display device, in-vehicle system, and vehicle equipped therewith

Abstract

The present invention provides a more suitable display device or display technology. The present invention contributes to Sustainable Development Goal 3, "Good Health and Well-being for All." [Solution] In a display device that displays a virtual image on the windshield of a vehicle, the display device comprises a light source that emits light, a light direction conversion panel that converts the direction of the light emitted from the light source, and a display panel that emits the optical image converted by the light direction conversion panel.

Description

Technical Field

[0001] The present invention relates to a display device, an in-vehicle system, and a vehicle including the same.

Background Art

[0002] There is known a display device or a virtual image display device that projects video light onto a windshield or a front glass of a vehicle such as an automobile to display a virtual image, and displays driving information such as vehicle speed and engine speed, traffic information from navigation, and vehicle information such as remaining fuel and coolant temperature.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The display device is disposed, for example, on or inside the dashboard of the vehicle. When using the display device, the driver can obtain the information necessary for driving without moving the line of sight to the instrument panel incorporated in the dashboard, that is, the so-called instrument panel. On the other hand, sufficient consideration has not been given to the arrangement, brightness, influence from external light, information display, etc. of the display device.

[0005] An object of the present invention is to provide a more suitable display device or display technology.

Means for Solving the Problems

[0006] According to an aspect of the present invention, the following display device is provided. In a display device that displays a virtual image on a windshield of a vehicle, the display device includes a light source that emits light, an optical direction conversion panel that converts the direction of the light emitted from the light source, and a display panel that emits an optical image converted by the optical direction conversion panel. [Effects of the Invention]

[0007] According to the present invention, a more suitable display device or display technology can be realized. Other problems, configurations, and effects not mentioned above will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows an example of an in-vehicle system including a display device. [Figure 2] This figure shows an example of a device used to acquire vehicle information. [Figure 3] This is a block diagram showing an example of a display device. [Figure 4] This figure shows an example of a configuration in which a display device is installed in a vehicle. [Figure 5] This figure shows an example of a configuration in which a display device is installed in a vehicle. [Figure 6] This figure shows an example of a light source structure for a display device. [Figure 7] This is a system configuration diagram of an in-vehicle system, including a display device. [Figure 8] This figure shows an example of a top view of a display device mounted on a vehicle. [Figure 9] This diagram illustrates how the image light from a display device is perceived as a virtual image. [Figure 10] This figure shows an example of a virtual image displayed on a windshield. [Figure 11] This is a cross-sectional view illustrating the distortion of virtual images in a windshield. [Figure 12A] This is a front view showing a distorted virtual image in the windshield. [Figure 12B] This is a top view showing the image light emitted from the image display element of a display device. [Figure 13A] This is a front view showing a virtual image in the windshield. [Figure 13B] This is a top view showing the image light emitted from the image display element of a display device. [Figure 14A] Another front view showing a virtual image on the windshield. [Figure 14B] Another top view showing the video light emitted from the video display element of the display device. [Figure 15] A top view showing the video display element of the display device. [Figure 16] A front view showing a virtual image on the windshield. [Figure 17] A top view showing the reference point of the video display element of the display device. [Figure 18] A view showing the rotation axis of the video display element of the display device. [Figure 19] Another top view showing the video display element of the display device. [Figure 20] Another front view showing a virtual image on the windshield. [Figure 21] Another cross-sectional view explaining the distortion of the virtual image on the windshield. [Figure 22] Another top view showing the video display element of the display device. [Figure 23] Another front view showing a virtual image on the windshield. [Figure 24] A view showing an example of a virtual image after the distortion displayed on the windshield is corrected. [Figure 25] A view showing a virtual image from the video display element of the display device. [Figure 26] A detailed view showing a virtual image from the video display element of the display device. [Figure 27] A detailed view showing a virtual image from the video display element of the display device. [Figure 28] Another view showing a virtual image from the video display element of the display device. [Figure 29] A detailed view of the video display element of the display device. [Figure 30] An explanatory view of the video light of the display device. [Figure 31] A configuration diagram of the light direction conversion panel of the display device. [Figure 32]This is a diagram illustrating the configuration of the optical direction conversion panel for a display device. [Figure 33] This diagram shows virtual images from the image display elements of two display devices. [Figure 34] This is another diagram showing virtual images from the video display elements of two display devices. [Figure 35] This is another diagram showing virtual images from the video display elements of two display devices. [Figure 36] This is another diagram showing a virtual image from the video display element of a display device. [Figure 37] This is a detailed diagram of the video display element of a display device. [Figure 38A] This is an explanatory diagram of the image light of a display device. [Figure 38B] This is another diagram illustrating the image light of a display device. [Figure 39] This is a diagram illustrating the configuration of the optical direction conversion panel for a display device. [Figure 40A] This is an explanatory diagram of the optical direction conversion panel for a display device. [Figure 40B] This is an explanatory diagram of the optical direction conversion panel for a display device. [Figure 41] This is a detailed diagram showing an example of a configuration in which a display device is installed in a vehicle. [Figure 42] This diagram shows the details of the light guide section within the display device. [Figure 43] This is another diagram showing an example of the light source structure of a display device. [Figure 44] This is a detailed diagram showing another example of a configuration in which a display device is mounted on a vehicle. [Figure 45A] This figure shows an example of a side view of the light source structure of a display device. [Figure 45B] This figure shows an example of a front view of the light source structure of a display device. [Figure 45C] This figure shows an example of a perspective view of the light source structure of a display device. [Figure 46A] This is another diagram showing an example of a side view of the light source structure of a display device. [Figure 46B] This is another diagram showing an example of a front view of the light source structure of a display device. [Figure 46C]This is another diagram showing an example of a perspective view of the light source structure of a display device. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. The embodiments are illustrative examples for explaining the present invention, and have been omitted and simplified as appropriate for clarity of explanation. The present invention can also be implemented in various other forms. Unless otherwise specified, each component may be singular or plural. The position, size, shape, and range of each component shown in the drawings may not represent the actual position, size, shape, and range in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the position, size, shape, and range disclosed in the drawings. When there are multiple components that have the same or similar function, they may be described using the same reference numeral with different subscripts. Also, when it is not necessary to distinguish between these multiple components, the subscripts may be omitted in the description.

[0010] In explanations, when describing program-based processing, the focus may be on the program, its functions, or its processing units. The main hardware components are the processor, or controllers, devices, computers, and systems composed of such processors. The computer, using its processor, executes processing according to the program read into memory, utilizing resources such as memory and communication interfaces as appropriate. This realizes the specified functions and processing units. The processor is composed of semiconductor devices such as CPUs / MPUs and GPUs. Processing is not limited to software programs; it can also be implemented using dedicated circuits. FPGAs, ASICs, CPLDs, etc., are applicable as dedicated circuits.

[0011] The program may be pre-installed as data on the target computer, or it may be distributed as data to the target computer from the program source. The program source may be a program distribution server on a communication network, or a non-transient computer-readable storage medium, such as a memory card or disk. The program may consist of multiple modules. The computer system may consist of multiple devices. The computer system may consist of a client-server system, a cloud computing system, an IoT system, etc. Various types of data and information are composed of structures such as tables and lists, but are not limited to these. Representations such as identification information, identifiers, IDs, names, and numbers are interchangeable.

[0012] Figure 1 shows an example configuration of an in-vehicle system including the display device 1. With respect to the vehicle or ride and the driver, the horizontal direction X is the left-right direction, the lateral direction of the vehicle or ride, or the width direction of the vehicle or ride. The vertical direction Z is the up-down direction, or vertical direction, of the vehicle. The horizontal direction Y, perpendicular to the lateral direction of the vehicle or ride, is the front-rear direction of the vehicle or ride, or the direction of travel of the vehicle. In the example in Figure 1, the direction of travel of the vehicle is set to be the negative direction in the Y-axis direction. The display device 1 may also be called a virtual image display device. Hereafter, the term "display device" will be used. A vehicle or ride is typically an automobile or truck, but is not limited to these; it may also be a motorcycle, railway car, aircraft, ship, or other moving object. Hereafter, these vehicles will be referred to as vehicles.

[0013] The display device 1 acquires vehicle information 4 from cameras and various sensors installed in various parts of the vehicle 2. The various sensors, for example, detect various events that occur in the vehicle 2 and periodically detect the values ​​of various parameters related to driving conditions. It can also acquire road information and GPS (Global Positioning System) information from a navigation device 6 (car navigation system), external devices 400, terminal devices 410 (e.g., mobile terminals). The GPS may be installed in the vehicle 2, or it may be installed in the external devices 400 or terminal devices 410.

[0014] Vehicle information 4 includes, for example, vehicle 2's speed information, gear information, steering angle information, lamp illumination information, ambient light information, distance information, infrared information, engine ON / OFF information, camera image information, accelerometer / gyro information, GPS (Global Positioning System) information, navigation information, vehicle-to-vehicle communication information, and vehicle-to-infrastructure communication information. Camera image information includes in-vehicle camera images and exterior camera images. GPS information includes latitude and longitude as well as current time information. Vehicle information 4 also includes input information from the driver.

[0015] The display device 1 is connected to the controller 100 of the vehicle 2 via an information transmission path, and the display device 1 and the controller 100 are able to communicate. The controller 100 of the vehicle 2 is an ECU (Electronic Control Unit). The display device 1 and the controller 100 of the vehicle 2 communicate via the information transmission path, for example, using a CAN (Controller Area Network) or LIN (Local Interconnect Network) interface. Alternatively, the display device 1 and the controller 100 of the vehicle 2 may communicate via the information transmission path using an in-vehicle Ethernet or the like. Other wired or wireless connection methods may also be used. For example, when transmitting all information, including video information, via a single information transmission path, the connection between the controller 100 on the vehicle 2 side (the source of video information, etc.) and the display device 1 (in other words, the connection method of the information transmission path) may be FPD-Link III, GMSL (Gigabit Multimedia Serial Link), etc.

[0016] The in-vehicle system 300 is configured such that the controller 100 controls the vehicle 2 based on data input and output and is connected to the display device 1. The in-vehicle system 300 can communicate with the outside of the vehicle 2 via a communication device or network. Examples of communication with the outside of the vehicle 2 include direct communication and indirect communication. Direct communication is a method used internationally for ITS (Intelligent Transport System) communication, while indirect communication is a method of communication that is performed indirectly, for example, via a server to an external device 400 or terminal device 410. The in-vehicle system 300 can send and receive data or information with, for example, a server 700 connected to the network 500 via a relay station 600 on the network 500. The in-vehicle system 300 may also communicate with infrastructure such as external devices and terminals installed on the road on which the vehicle 2 travels.

[0017] Figure 2 shows an example of a device used to acquire vehicle information. As shown in Figure 2, vehicle information 4 is acquired using devices such as a camera and various sensors connected to the controller 100 or control device. Note that the various devices in Figure 2 can be deleted, other types of devices added, or replaced with other types of devices as appropriate. Also, as an example, the controller 100 of vehicle 2 may also have the function of controlling the display device 1.

[0018] The vehicle speed sensor 901 detects the speed of vehicle 2 and is used to generate speed information as a result of the detection. The shift position sensor 902 detects the current gear and is used to generate gear information as a result of the detection. The steering angle sensor 903 detects the current steering angle and is used to generate steering angle information as a result of the detection. The headlight sensor 904 detects whether the headlights are ON or OFF and is used to generate lamp illumination information as a result of the detection.

[0019] The illuminance sensor 905 and the chromaticity sensor 906 detect ambient light from the vehicle 2 and are used to generate ambient light information as detection results. The distance measuring sensor 907 detects the distance between the vehicle 2 and an external object, or the distance between external objects, and is used to generate distance information as detection results. The infrared sensor 908 detects the presence and distance of objects in the vicinity of the vehicle 2 and is used to generate infrared information as detection results. The engine start sensor 909 detects the ON / OFF status of the engine and is used to generate ON / OFF information as detection results. The acceleration sensor 912 and the gyro sensor 913 detect the acceleration and angular velocity of the vehicle 2 and are used to generate acceleration gyro information representing the attitude and behavior of the vehicle 2.

[0020] The temperature sensor 914 detects the temperature inside and outside the vehicle and is used to generate temperature information as the detection result. For example, if the display device 1 is located inside the dashboard of the vehicle 2, the temperature sensor 914 may be used to detect the temperature inside the dashboard. If a temperature that may affect the operation of the display device 1 is detected, the display device 1 may stop operating. The temperature sensor 914 may also be located in other places that may experience temperatures similar to those inside the dashboard.

[0021] Furthermore, if the display device 1 is installed on the dashboard or elsewhere, the temperature sensor 914 may be used to detect the temperature in the vicinity where the display device 1 is installed. If a temperature is detected that may affect the operation of the display device 1 due to direct sunlight or the like, the display device 1 may stop operating. Here, the temperature sensor 914 may be placed on the dashboard as an example. The temperature sensor 914 may also be placed outside the vehicle, assuming that the temperature near the display device 1 and the temperature outside the vehicle are similar.

[0022] The vehicle-to-infrastructure wireless transceiver 915 generates vehicle-to-infrastructure communication information through vehicle-to-infrastructure communication between vehicle 2 and roads, signs, signals, etc. The vehicle-to-vehicle wireless transceiver 916 generates vehicle-to-vehicle communication information through vehicle-to-vehicle communication between vehicle 2 and other surrounding vehicles. The wired wireless communication unit 917 for mobile terminal-to-vehicle communication is a device that acquires information from devices connected to the LTE (Long Term Evolution) network (e.g., WiFi devices) via wired or wireless communication. The controller 100 or control device can acquire information transmitted and received on the LTE network via the wired wireless communication unit 917 for mobile terminal-to-vehicle communication.

[0023] The in-vehicle camera 919 and the exterior camera 920 capture images of the interior and exterior of the vehicle and are used to generate in-vehicle and exterior camera image information. Specifically, the in-vehicle camera 919 is, for example, a camera for a Driver Monitoring System (DMS) that captures the driver's posture, eye position, and movement. In this case, by analyzing the captured images, the driver's fatigue level and gaze position can be determined.

[0024] On the other hand, the external camera 920 captures images of the surroundings, such as the front and rear of vehicle 2. In this case, the external camera 920 analyzes the captured images to determine the presence or absence of obstacles such as other vehicles or people in the vicinity, buildings and terrain, road surface conditions such as rain, snow, ice, and unevenness, and road signs. The external camera 920 also includes, for example, a dashcam that records the situation while driving.

[0025] The GPS receiver 921 generates GPS information obtained by receiving GPS signals from GPS satellites. For example, a device used to acquire vehicle information can obtain the current time, latitude, and longitude using the GPS receiver 921. The VICS (Vehicle Information and Communication System, registered trademark) receiver 922 generates VICS information obtained by receiving VICS signals. The GPS receiver 921 and the VICS receiver 922 may be provided as part of a navigation system.

[0026] The voice input device 918 receives the driver's voice and is used to generate voice information. The driver can input operation details via the voice input device 918 by speaking. The vehicle operation switch 911 is used to generate driver operation information for steering wheel switches, etc.

[0027] Furthermore, the video generation unit 910 generates video information based on vehicle information 4 acquired by the controller 100 of the vehicle 2. The video generation unit 910 can also generate video information based on external information.

[0028] Figure 3 is a block diagram of the display device 1. Figure 3 mainly shows the control of the display of projected images (including virtual images) in the display device 1.

[0029] In Figure 3, the display device 1 includes, for example, a control unit 1010, a non-volatile memory 1011, a volatile memory 1012, a storage unit 1013, a display driver 1021, and a light source drive unit 1022, all of which are mounted on a wiring board or the like. The display device 1 also includes a communication unit 1014, a wireless communication unit 1015, a video processing unit 1016, an operation input unit 1017, an external power input unit 1018, a speaker 1019, and a light-emitting indicator 1020.

[0030] The control unit 1010 is specifically a microcontroller (MCU) or a CPU (Central Processing Unit). Each block other than the control unit 1010 may be mounted within the control unit 1010 as appropriate. Furthermore, the display device 1 is not limited to implementation using the control unit 1010; it may also be implemented using an ECU (Electronic Control Unit) or other semiconductor devices. The configuration shown in Figure 3 may, for example, involve a control unit mounted inside the housing of the display device 1, or a control unit mounted outside the housing. Additionally, the display device 1 can be controlled by a controller in the vehicle 2 or an external device without implementing the control unit 1010 within the display device 1.

[0031] The non-volatile memory 1011 primarily stores programs executed within the control unit 1010, setting parameters used in the processing of each part within the control unit 1010, and predefined audio and video data. The non-volatile memory 1011 may also store information other than programs, such as video, audio, and video.

[0032] The volatile memory 1012 operates by expanding the program stored in the non-volatile memory 1011. The volatile memory 1012 primarily processes acquired information and various data used in the processing of each part within the control unit 1010 as appropriate.

[0033] The storage unit 1013 stores video data, video data, or audio data for output to the speaker 1019, etc. The video data, video data, or audio data to be stored in the storage unit 1013 may be stored in the storage unit 1013 in advance. Alternatively, the video data, video data, or audio data to be stored in the storage unit 1013 may be received from an external device via the communication unit 1014.

[0034] In Figure 3, the communication unit 1014 transmits and receives information such as vehicle information 4 to and from the controller 100 of the vehicle 2 or various devices such as sensors of the vehicle 2, using a mechanism such as CAN or in-vehicle Ethernet. The communication unit 1014 may also receive video information using a mechanism such as FPD-Link III or GMSL. The hardware of the communication interface that receives vehicle information 4 and the hardware of the communication interface that receives video information in the communication unit 1014 may be separate or integrated. Furthermore, the communication unit 1014, which transmits and receives information via a wired or wireless connection using a connector that connects to a plug, may also function as the control unit of the display device 1.

[0035] The wireless communication unit 1015 may be configured with a Wi-Fi communication interface, a Bluetooth® communication interface, a mobile communication interface such as 4G or 5G, etc. As shown in Figure 1, the wireless communication unit 1015 may communicate with external devices via a network 500 connected through a router or relay station 600. An example of an external device is a server 700 connected via network 500. Alternatively, the wireless communication unit 1015 may communicate directly with a terminal device 410, etc. An example of a terminal device 410 is a smartphone, tablet, wireless earphones, headphones, or beacon.

[0036] The video processing unit 1016 may perform distortion correction, conversion, and other processing on the received video information. The display device 1 can avoid distortion of the virtual image displayed on the windshield 3 or windshield by setting the installation position of the display device 1, but the video processing unit 1016 may generate video data directed to the video display unit 200 using acquired vehicle information, external information, etc. Specifically, the distortion correction by the video processing unit 1016 corrects the distortion of the image that occurs due to a predetermined curvature of the windshield 3 or windshield when the image from the display device 1 is projected onto the display area 5 as a display area, as shown in Figure 1. The video processing unit 1016 may also be implemented by the control unit 1010 reading and executing a program stored in the non-volatile memory 1011 or volatile memory 1012.

[0037] In other words, the video processing unit 1016 processes video data related to the display video projected onto the display area 5, such as in Figure 1, based on information acquired from an external source or from the vehicle 2. On the other hand, the system does not necessarily have a video processing unit 1016; in such a case, the control unit 1010 can process video information from the vehicle 2 or an external terminal via the communication unit 1014. Alternatively, the controller 100 of the vehicle 2 may process the video information.

[0038] The operation input unit 1017 is, for example, an operation button, a receiver for a remote controller, or an infrared light receiver, and is used to input user operations. The operation input unit 1017 may be used, for example, for the driver to operate the display device 1.

[0039] The external power input unit 1018 has a power connector for supplying power, and power is input from an external source by connecting the power connector to a wired connection terminal (power plug), supplying the necessary power to each part of the display device 1 shown in Figure 3.

[0040] The speaker 1019 emits sound based on audio data stored in the volatile memory 1012, the non-volatile memory 1011, or the storage unit 1013.

[0041] The light-emitting indicator 1020 emits light using a light-emitting element or the like, and can notify the user of the status of the display device 1 by the timing of the light emission of the light-emitting element or the color of the emitted light.

[0042] The display driver 1021 drives each display element (pixel) included in the display panel 11 based on the video data. This allows the video display unit 200 to create and display an image for projection onto the display area 5 based on the video data. The display driver 1021 can be configured, for example, by a circuit mounted on a circuit board.

[0043] The light source drive unit 1022 drives the light source 20 to generate light. Based on the drive, the light source drive unit 1022 causes the light source 20 to generate light and supply it to the display panel 11. Vehicle information 4 received via the communication unit 1014, or information from terminal devices, etc., is used to adjust or control the light source 20 using the light source drive unit 1022, which is the driver used to drive the light source.

[0044] Furthermore, the display device 1 may protect the display panel 11 based on ambient light information from the illuminance sensor 905 shown in Figure 2. That is, in order to prevent the display panel 11 from being burned out by sunlight, the display device 1 may perform an operation to protect the display panel 11 from sunlight according to the value of the illuminance sensor 905. More specifically, if the intensity of ambient light or sunlight acquired by the illuminance sensor 905 is strong and there is a risk of the display panel 11 being burned out, the brightness of the light source 20 is reduced, and the amount of light from the light source 20 incident on the display panel 11 is suppressed, thereby suppressing the temperature rise of the display panel 11.

[0045] Each component in Figure 3 may be implemented using a dedicated circuit such as an FPGA (Field Programmable Gate Array) as appropriate. In this embodiment, the display device 1 has a configuration that includes a non-volatile memory 1011, a volatile memory 1012, a storage unit 1013, and a video processing unit 1016, but the above processing may be performed by a single memory.

[0046] Next, the video display unit 200 will be described in detail. Based on video data, the video display unit 200 projects video light from the light source 20 (in other words, light source light) onto the display panel 11. The video display unit may also be called a projection-type video display device or a projector. The video display unit 200 comprises a light source 20 and a display panel 11 such as a liquid crystal display (LCD) having video display elements.

[0047] The light source 20 functions as a backlight source for the display panel 11. The light source 20 is configured, for example, using a semiconductor light source element, and generates a predetermined light source and supplies it to the display panel 11. Typically, an LED (Light Emitting Diode) element is used as the semiconductor light source element. The light source 20 may also be configured by arranging multiple light sources. The light source unit (backlight unit) 12, which will be described later, may be configured using the light source 20 or the like.

[0048] The display panel 11 generates and emits modulated video light based on the light source. In other words, the display panel 11 forms and displays an image on the display screen based on video data, and generates and emits video light corresponding to the image based on the light from the light source 20. The video data in this embodiment will be described as video data input from the video processing unit 1016. The display panel 11 forms an image to be projected onto the display area 5 by modulating the light from the light source 20 pixel by pixel according to the video data, and projects it as video light (in other words, projected light).

[0049] Furthermore, the display panel 11 is not limited to a liquid crystal panel; it may also be a screen plate with a diffusion function. The means for projecting an image onto the screen plate with a diffusion function may include a means of projecting an image from a DMD (Digital Micromirror Device) or a liquid crystal panel in combination with a projection lens, or a means of using a micro electro-mechanical system.

[0050] Figures 4 and 5 show examples of configurations in which the display device 1 is mounted on a vehicle 2. Figure 4 shows an example of mounting the display device 1 on a passenger car. Passenger cars include sports cars, sedans, SUVs (Sport Utility Vehicles), and minivans, where the angle of the windshield 3 or windshield is 20° to 45° with respect to the Y-axis (the longitudinal direction or direction of travel of the vehicle 2). Figure 5 shows an example of mounting the display device 1 on some passenger cars and commercial vehicles, in other words, the windshield 3 or windshield in Figure 5 is in the upright position. Specifically, these include light super-height wagons, trucks, and buses, where the angle of the windshield 3 or windshield is 45° to 90° with respect to the Y-axis (the longitudinal direction or direction of travel of the vehicle 2). As shown in Figures 4 and 5, the display device 1 is located on the dashboard 7 of the vehicle 2. The display device 1 may also be implemented so as to be embedded within the dashboard 7. The dashboard 7 also includes an instrument panel, for example, a meter cluster in front of the steering wheel.

[0051] As shown in Figures 4 and 5, the image light 13 in Figure 4 is emitted toward the driver, and the image light 13 in Figure 5 is emitted toward the windshield 3 or windshield. The image light 13 emitted from the display device 1 is reflected when it is irradiated by the windshield 3 or windshield. The emitted image light 13 reflected by the windshield 3 or windshield is incident on the driver's viewpoint 14 as a projected image. Also, from the driver's viewpoint 14, a virtual image 10 corresponding to the image light 13 is formed in the direction of the display area 5 (Figure 1) of the display device 1 corresponding to the irradiation area of ​​the image light 13, and can be seen as a virtual image 10. This embodiment describes projecting image light onto the display area 5 of the windshield 3 or windshield, but the projection area that turns the image light into a projected image may be other projection members other than the windshield 3 or windshield. Furthermore, the display device 1 may emit the image light 13 directly toward the driver. The display device 1 may also project floating images simultaneously.

[0052] Figure 6 shows the video display unit 200 of the display device 1. The light source unit 12 may also be called the backlight unit. The light source unit 12 includes a light source 20, a reflective mirror 21, a polarization conversion element 22, and a light guide unit 23, and may also include a diffuser plate 24. The reflective mirror 21 is used to reflect light from the light source 20 and adjust it to parallel light. The reflective surface of the reflective mirror 21 is a parabolic surface and may be asymmetrical with respect to the optical axis of the light emitted from the light source 20. The reflective mirror 21 may also be positioned eccentrically with respect to the light source 20. The reflective mirror 21 may also be called a reflector.

[0053] The polarization conversion element 22 is composed of a polarizing beam splitter (PBS) and a phase difference film (1 / 2λ). The polarization conversion element 22 separates incident light into S-polarized and P-polarized light, and then polarizes either the separated S-polarized or P-polarized light using the phase difference film (1 / 2λ) to emit the randomly polarized light incident on the polarization conversion element 22 as linearly polarized light.

[0054] The light guide unit 23 may also be called an optical transmission unit. The light guide unit 23 is configured to adjust the angle of incidence of light rays to the display panel 11, and in this example, it is configured using an optical reflecting unit 23a having a prism shape (a jagged shape). The light guide unit 23 may also be a prism sheet as an example. In this example, the light rays incident on the optical reflecting unit 23a of the light guide unit 23 are adjusted to a predetermined light distribution and reflected toward the display panel 11. The distribution of light incident on the display panel 11 can be adjusted by the shape of the reflective surface of the optical reflecting unit 23a, the inclination of the reflective surface, the surface roughness, etc. In the display device 1, the optical axis of the light source 20 and the optical axis of the light incident on the display panel 11 are parallel or approximately parallel.

[0055] The light guide 23 is, for example, a resin member having a prism shape, and the light-reflecting portion 23a of the prism-shaped part that becomes the reflective surface is coated with an Al reflective film or the like. The light-reflecting portion 23a of the light guide 23 may be configured to have multiple inclinations on one surface in order to achieve more precise adjustment of reflected light. The reflective surface may also be composed of multiple or multifaceted surfaces, or it may be composed of a curved surface. When a large number of reflective surfaces and connecting surfaces are formed alternately in a sawtooth pattern on the light-reflecting portion 23a, the light incident on the light guide 23 is reflected on each reflective surface and directed toward the display panel 11, and further adjusted to a predetermined light distribution characteristic via the diffuser plate 24 before incident on the display panel 11. The diffuser plate 24 uniformly disperses the incident light from the light guide 23. The diffuser plate 24 has the effect of improving the brightness uniformity within the virtual image plane.

[0056] Furthermore, the video display unit 200 may have a configuration other than that shown in Figure 6, and may, for example, include a light source, an illumination optical system, a PBS or polarization separation element, and a reflective liquid crystal panel or LCOS.

[0057] Figure 7 is a system configuration diagram of the in-vehicle system 300, including the display devices. The in-vehicle system 300 is equipped with multiple display devices, for example, three display devices 1L, 1C, and 1R. Note that there may be multiple display devices, and depending on the size of the dashboard 7 in which they are installed, there may be two or four or more. In the following description, we will explain the case in which the dashboard 7 is equipped with three display devices. With this configuration, the driver can perceive in a balanced manner the virtual image obtained from the image light emitted from the centrally located display device and the virtual images obtained from the image light emitted from the display devices located to the left and right of the central virtual image. Note that in the explanation from Figure 7 onward, the case in which the vehicle has a windshield is used as an example, but the same considerations may be applied to the windshield.

[0058] Display devices 1L, 1C, and 1R acquire vehicle information from vehicle 2 or external information from external device 400. Display devices 1L, 1C, and 1R are connected to the controller 100, external device 400, and vehicle 2 via a wired information transmission path (bus) or wirelessly, and transmit and receive information.

[0059] Furthermore, the image light 13 emitted from the display devices 1L, 1C, and 1R is incident on the windshield 3 of the vehicle 2 at a predetermined incident angle. The windshield 3 reflects the image light 13 and emits the image light 13 (reflected light) toward the driver at a predetermined emission angle. In other words, the display devices 1L, 1C, and 1R emit the image light 13 toward the driver.

[0060] The controller 100 controls the vehicle 2 based on data input and output. The controller 100 also controls the direction of light emission from the display devices 1L, 1C, and 1R in conjunction with each other. The control of the display devices 1L, 1C, and 1R in conjunction with each other may be performed by a control unit that works in conjunction with the controller 100, rather than by the controller 100.

[0061] Figure 8 shows an example of a top view of a display device mounted on a vehicle. The vehicle 2, in which the driver 140 is seated, has a windshield 3 positioned as a reflective material with curvature that reflects the image light 13. As shown in Figure 8, the windshield 3 is positioned above the top surface of the dashboard 7 when the vehicle 2 is viewed from above. The bottom surface 3a of the windshield 3 may be curved. Also, the front end 7f of the dashboard 7 in the direction Y in which the vehicle 2 is traveling is curved. The bottom surface 3a of the windshield 3 and the front end 7f of the dashboard 7 are positioned to face and be aligned with each other.

[0062] Multiple display devices 1 may be placed on the dashboard 7 or housed within the dashboard 7. When multiple display devices 1 are housed within the dashboard 7, the dashboard 7 has multiple openings arranged linearly in direction X, which is the width direction of the vehicle 2. Each opening is formed in the dashboard 7 corresponding to the image light emission surface of each display device. For example, when three display devices are placed within the dashboard 7, the dashboard 7 is assembled and installed with three linearly arranged display devices 1L, 1C, and 1R that are exposed or visible through the three openings. Alternatively, when placed on the dashboard 7, the three linearly arranged display devices 1L, 1C, and 1R are assembled and installed according to the bottom surface 3a of the windshield 3. The installation positions of the display devices 1L, 1C, and 1R can also be adjusted after assembly. The left-side display device 1L includes an image display element 25L. Similarly, the central display device 1C is equipped with a video display element 25C, and the right-side display device 1R is equipped with a video display element 25R. The three display devices are equipped with identically shaped video display elements 25L, 25C, and 25R that are arranged linearly in the direction X.

[0063] Figure 9 is a diagram illustrating how the image light from the display device is perceived as a virtual image. The display devices 1L, 1C, and 1R in Figure 8 project image light 13, the windshield 3 reflects the image light 13, and the reflected image light 13 enters the driver's viewpoint 14. From the driver's viewpoint 14, virtual images 10L, 10C, and 10R corresponding to the image light 13 are formed in the direction of the display area 5 (Figure 1) corresponding to the illuminated area of ​​the image light 13, and the driver can see the virtual images 10L, 10C, and 10R simultaneously.

[0064] The virtual images 10L, 10C, and 10R are displayed on the windshield 3 between the A-pillars 8L and 8R. This windshield 3 has curvature. Therefore, the rectangular virtual images 10L and 10R, which are the display images of the image light 13 projected from the image display elements 25L and 25R of the left and right display devices 1L and 1R located on the left and right sides, are distorted in their rectangular shape. In addition, the virtual images 10L and 10R have uneven height positions in the vertical direction (direction Z) of the vehicle and are not displayed horizontally aligned with the virtual image 10C. In this embodiment, the virtual image 10L and the virtual image 10R are symmetrical with respect to the central axis of the virtual image 10C in the vertical direction (Z-axis) of the vehicle.

[0065] Figure 10 shows an example of virtual images 10L, 10C, and 10R displayed on the windshield 3. Virtual image 10L displays entertainment information such as a music playlist. Virtual image 10L is entertainment information obtained through mirroring with an external device 400 such as a smartphone or a personal music player, or through integration with the in-vehicle system. The external device 400 may be a music player installed in the vehicle.

[0066] Icons related to the operation of the external device 400 visually indicate that an operation has been performed on the interface of the external device 400, and that the operation has been reflected. For example, the icon may change color or brightness to be highlighted. This visually indicates that the operation of the external device 400 has been reflected.

[0067] The play / pause icon 31a changes depending on the play / pause operation of the external device 400. During music playback, the play / pause icon 31a is illuminated. When playback is stopped, it displays a different icon shape or is darkened. The fast-forward / next track play icon 31b changes depending on the fast-forward or next track playback operation of the external device 400. During fast-forwarding, the play / pause icon 31a is highlighted by blinking or other means. When the next track is playing, it is highlighted by being lit up or other means.

[0068] The rewind / previous track playback icon 31c changes depending on whether the external device 400 is used for rewinding or playing the previous track. During rewinding, the rewind / previous track playback icon 31c is highlighted by blinking or other means. During playback of the previous track, it is highlighted by being lit up or other means. The favorites icon 31d indicates that the currently playing song is registered as a favorite. If it is not registered, the favorites icon 31d will be hidden or dimmed.

[0069] The shuffle playback icon 31e indicates that the song in the playlist is set to play randomly. When random playback is not enabled, or when it is not set, the shuffle playback icon 31e will be hidden or dimmed.

[0070] The total length display 31f shows the length (duration) of the currently playing song. The elapsed playback time display 31g shows the time elapsed from the start of playback of the song to the present. The seek bar (playback bar) icon 31h is a more visual representation of the total length display 31f and the elapsed playback time display 31g. The length of the seek bar (playback bar) icon 31h is the total length of the total length display 31f. The position of the circle on the seek bar (playback bar) icon 31h indicates the time elapsed playback time display 31g.

[0071] The virtual image 10C displays driving assistance information such as map and navigation information. The virtual image 10C is navigation information obtained by mirroring with an external device 400 such as a smartphone or a user-provided navigation device, or by linking with the in-vehicle system. The external device 400 may be an in-vehicle navigation device.

[0072] The displays and icons related to the external device 400 visually indicate that the display on the interface of the external device 400 has been reflected. For example, the icon may change color or brightness, or it may move and be highlighted. This visually indicates that the display of the external device 400 has been reflected.

[0073] The virtual image 10C displays a two-dimensional or three-dimensional (sky view) map representing roads, buildings, etc., as well as the positional relationship between the vehicle, the destination, and the vehicle and the destination on the map.

[0074] The vehicle icon 32a represents the location of the vehicle on the map. The destination icon 32b represents the destination on the map. The route display 32c highlights the relative positions of the vehicle and the destination as a route.

[0075] Building / site display 32d is a schematic representation of buildings, obstacles, etc., that exist on the map. Road display 32e is a schematic representation of roads, etc., that exist on the map.

[0076] Furthermore, the display of the vehicle icon 32a, destination icon 32b, route display 32c, etc., switches according to the current location of the vehicle's movement.

[0077] The virtual image 10R displays driving assistance information such as vehicle speed and turn signal information. The virtual image 10R includes navigation information from external devices 400 such as smartphones or personal navigation devices, and vehicle information from sensors installed in the vehicle.

[0078] The virtual image 10R display and icons visually represent navigation information, vehicle information, and even direction indicator information. For example, icons may change color or brightness, or move to highlight them for visual representation.

[0079] The current direction of travel indicator icon 33a is an icon that provides real-time direction of travel and navigation. The current direction of travel indicator icon 33a indicates that the immediate direction of travel is to the left, for example, by sequentially flashing three triangular marks to the left. In other words, the current direction of travel indicator icon 33a is indicating that the vehicle should move to the left at this moment. The current direction of travel indicator icon 33a can be switched and displayed as needed between three triangular marks indicating forward movement (an icon that rotates the left-indicating icon 90° clockwise) or three triangular marks indicating right movement (an icon that rotates the left-indicating icon 180° clockwise).

[0080] The vehicle speed display 33b shows the vehicle speed in real time. For example, it shows that the current vehicle speed is 100 km / h. The road sign icons 33c are displayed according to the current vehicle position, and include guide signs, warning signs, regulatory signs, and instructional signs. For example, it displays a regulatory sign indicating that the maximum speed is 100 km / h.

[0081] The AR display 33d is a white line auxiliary display that clearly indicates the position of white lines in poor visibility conditions, nighttime, etc. The AR display 33d is displayed overlaid on the white lines on the road. The AR display 33d may also display arrow marks to indicate lane changes, etc., or enclosed in a circle or other frame to indicate detected obstacles, etc. The shift position icon 33e displays the status of the shift gear. For example, the shift position icon 33e displays the drive gear as "D" while driving.

[0082] The intersection name / destination name display 33f shows the name of the point to be reached from the current location in the future. For example, if the road name is ○▽□, the intersection name / destination name display 33f will display "Road name ○▽□". The direction of travel indicator icon 33g at the intersection indicates the driver's action at the point displayed on the intersection name / destination name display 33f. The remaining distance to the intersection / destination display 33h shows the remaining distance to the point displayed on the intersection name / destination name display 33f.

[0083] For example, if the intersection name / destination name display 33f is "Road name ○▽□", the remaining distance to the intersection / destination display 33h is "1000km", and the direction of travel indicator icon 33g at the intersection is a left-pointing arrow, it indicates that the vehicle should turn left at the road named ○▽□ 1000km away. The displays for the intersection name / destination name 33f, the remaining distance to the intersection / destination display 33h, and the direction of travel indicator icon 33g at the intersection switch according to the vehicle's current movement.

[0084] The incoming call notification icon 33i indicates that there is an incoming call on a smartphone or other mobile device, which is an external device 400, when the device is connected to the smartphone. The incoming call notification icon 33i is hidden when there is no incoming call on the smartphone.

[0085] The incoming call number display 33j works in conjunction with the incoming call notification icon 33i and, when linked with a mobile device such as a smartphone, displays the caller's phone number and other information when an incoming call is received on the smartphone. The display of the incoming call number display 33j may show the phone number or the name of the registered recipient corresponding to the phone number registered in the in-vehicle system or display device. Note that the incoming call number display 33j is hidden when there is no incoming call on the smartphone.

[0086] Thus, in Figure 10, because the windshield 3 has different curvatures in the horizontal and vertical directions, the virtual images 10L, 10C, and 10R displayed on the windshield 3 are distorted, with uneven height positions and not displayed horizontally.

[0087] In particular, the virtual image 10R projected from the right-side display device 1R is displayed on the bottom surface 3a of the windshield 3, which is lower than the virtual image 10C projected from the central display device 1C. Furthermore, the right edge of the virtual image 10R is displayed distorted on the bottom surface 3a of the windshield 3, which is even lower than the left edge (towards the center). Alternatively, in the vertical direction of the windshield 3, the right edge of the virtual image 10R is lower than the left edge of the virtual image 10R (the side adjacent to the display device 1C), causing the virtual image 10R to be displayed at an angle. Consequently, distortion occurs in the display content, such as displays and icons.

[0088] Similar to the virtual image 10R, the virtual image 10L is displayed on the bottom surface 3a of the windshield 3, which is lower than the virtual image 10C projected from the central display device 1C. The left edge of the virtual image 10L is displayed distortedly on the bottom surface 3a of the windshield 3, which is even lower than the right edge. Alternatively, in the vertical direction of the windshield 3, the right edge of the virtual image 10L (the side adjacent to the display device 1C) is higher than the left edge of the virtual image 10R, and the virtual image 10L is also displayed at an angle. As a result, distortion occurs in the display content such as icons for the virtual image 10L as well.

[0089] When these distorted virtual images 10R and 10L, and a virtual image 10C that is not distorted (or less distorted than virtual images 10R and 10L) are displayed simultaneously on the windshield 3, for example, the direction indicated by the nearest direction indicator icon 33a of virtual image 10R and the vehicle icon 32a, destination icon 32b, and route display 32c on the map displayed by virtual image 10C become unclear, making it difficult to determine the direction in which vehicle 2 is moving.

[0090] In other words, distortions and inconsistencies in the displayed image can lead to problems. For example, if an arrow icon used to indicate the direction of travel is distorted, the driver may misinterpret the direction of travel. Furthermore, inconsistencies in the height of the displayed image can increase the vertical movement of the driver's gaze, potentially hindering safe driving.

[0091] Figure 11 is a cross-sectional view illustrating the distortion of virtual images 10L, 10C, and 10R in a windshield 3 having a curvature of an aspherical region with a predetermined curvature. The image light 13 emitted from the display device 1L is reflected by the light ray reflecting portion 50L of the windshield 3. The image light 13 emitted from the display device 1R is also reflected by the light ray reflecting portion 50R of the windshield 3.

[0092] Since the windshield 3 has a symmetrical curvature, the light-reflecting sections 50L and 50R are located at the same height. Meanwhile, the image light 13 emitted from the central display device 1C is reflected by the light-reflecting section 50C of the windshield 3.

[0093] Therefore, in the vertical direction of the windshield 3, the light ray reflecting portion 50C is above the light ray reflecting portions 50R and 50L, and this height difference g causes distortion and unevenness in the virtual images 10L, 10C, and 10R. In addition, the curvature of the windshield 3 gradually increases from left to right, so for example, in the virtual image 10R, the right side is lower than the left side, causing distortion as shown in Figure 10.

[0094] In this case, if multiple display devices, such as two, four, or five, are mounted on the dashboard, the further a display device is positioned from the center line of the windshield 3 in the left-right direction, the lower its light-reflecting surface will be in terms of height. Conversely, the closer a display device is positioned to the center line in the left-right direction, the higher its light-reflecting surface will be in terms of height.

[0095] When a radius of curvature of approximately 3,000 mm was set near the image light reflecting area of ​​the windshield 3 for verification, a positional difference g of approximately 30 mm occurred between the image light reflecting areas 50C, 50R, and 50L. As a result, it was found that the distorted virtual images 10L and 10R had an angle difference of approximately 2.8° in the vertical direction relative to the observation viewpoint between the right and left edges of the display.

[0096] Figure 12A is a front view showing a distorted virtual image 10R reflected by the windshield 3 after video light is emitted from the video display element 25R of the display device 1R in a windshield 3 with curvature. Figure 12B is a top view showing the video light emitted from the video display element 25R of the display device 1R. In order to obtain the virtual image 10R reflected by the windshield 3, the video light emitted from the video display element 25R becomes video light with the image inverted.

[0097] Figure 13A is a front view showing the adjustment of the distorted virtual image 10R in Figure 12A. In Figure 13A, a windshield 3 with curvature emits image light from the image display element 25R of the display device 1R, and the distorted virtual image 10R reflected by the windshield 3 is compressed and adjusted to display the virtual image 10R'.

[0098] Figure 13B is a top view showing the video light emitted from the video display element 25R of the display device 1R. In Figure 13B, in order to obtain an adjusted virtual image 10R', the distortion adjustment display unit 25t, which has been reduced in size by masking or the like in the area of ​​the video display element 25R, emits video light that has been compressed or otherwise processed from all the display content that was displayed in the area of ​​the video display element 25R in Figure 12B. That is, the distortion adjustment display unit 25t, which is the effective area of ​​the video display element 25R, is, for example, the diagonal area from the front left to the rear right of the rectangular video display element 25R.

[0099] The masking area 25u, which is the area of ​​the image display element 25R other than the distortion adjustment display area 25t, is made invisible by controlling the image display element 25R so that it does not emit image light. Alternatively, the masking area 25u is covered with a masking material so that the image light emitted from the image display element 25R cannot pass through it.

[0100] By emitting image light from such a distortion adjustment display unit 25t, the virtual image 10R' reflected by the windshield 3 is displayed horizontally. However, such a virtual image 10R' cannot utilize the entire surface of the image display element 25R, and its width in the vertical direction (direction Z) is narrow, resulting in a small size. Therefore, the amount of information in the virtual image 10R' displayed by such a display device 1R is limited, which can make it difficult for the driver to recognize.

[0101] Figure 14A is another diagram showing the adjustment of the distorted virtual image 10R in Figure 12A. Figure 14A is a front view showing a virtual image reflected by the windshield 3, which has curvature, after video light is emitted from the video display element 25R of the display device 1R. Figure 14B is a top view showing the video light emitted from the video display element 25R of the display device 1R.

[0102] Figure 14B shows that in order to obtain a virtual image 10R' reflected and adjusted by the windshield 3, the area of ​​the image display element 25R is enlarged, and compressed image light is emitted, containing all the display content that was displayed in the area of ​​the image display element 25R in Figure 12B. In other words, in Figure 14B, the area of ​​the image display element 25R is enlarged so that the distortion adjustment display section 25t, which has thickness in the width direction of the diagonal from the front left to the rear right of the rectangular image display element 25R, becomes an effective area.

[0103] The method for increasing the area of ​​the image display element 25R is to use a display device 1R equipped with a large image display element 25R. Alternatively, this can be achieved by widening the area of ​​the masking portion 25u that controls the image display element 25R so that it does not emit image light in the diagonal width direction, or by narrowing the area of ​​the masking portion 25u covered by the masking member in the diagonal width direction.

[0104] Furthermore, the display device 1R may be configured to obtain a more rectangular virtual image 10R' by making the shape of the diagonal of the distortion adjustment display unit 25t a distorted rectangle, and distorting the image light emitted from the distortion adjustment display unit 25t for display. The image light is distorted, for example, by the control of the display driver 1021 (see Figure 3) and displayed by the distortion adjustment display unit 25t. The display driver 1021 performs correction processing by rotating, compressing, shifting, etc., in a predetermined area of ​​the image data so that it is displayed distorted by the distortion adjustment display unit 25t, and drives each display element (pixel). As a result, the distortion adjustment display unit 25t displays distorted image light.

[0105] Furthermore, areas of the image display element 25R other than the distortion adjustment display section 25t are designated as non-display or masked sections 25u, similar to Figure 13B, and are not illuminated with image light. By illuminating from the distortion adjustment display section 25t, the virtual image 10R' reflected by the windshield 3 is displayed widely horizontally in the vertical direction (direction Z).

[0106] However, obtaining such a virtual image 10R' requires the video display element 25R to be elongated in the front-to-back direction (direction Y), resulting in a larger display device. Furthermore, the edges 25w of the enlarged video display element 25R interfere with the dashboard 7, limiting the extent of enlargement. Moreover, irregularly shaped video display elements that are not rectangular are less readily available and therefore more expensive, and their display control becomes more complex.

[0107] Next, we will explain the configuration for adjusting the virtual image shown in Figures 12A to 14B. Figure 15 is a top view showing the video display elements 25L, 25C, and 25R of the display devices 1L, 1C, and 1R. Display device 1L is assembled and installed in a position rotated counterclockwise, in the direction of the leftward arrow, relative to the display device in Figure 8, with the center of the video display element 25L as the reference point. Display device 1R is assembled and installed in a position rotated clockwise, in the direction of the rightward arrow, relative to the display device in Figure 8, with the center of the video display element 25R as the reference point. In this way, the three display devices, display devices 1L, 1R, and display device 1C, are arranged in the width direction of the dashboard 7, and each is installed in a position along the bottom surface 3a of the windshield 3. Note that the installation position of display devices 1R, etc., can be adjusted after assembly.

[0108] The display devices 1L and 1R are positioned in the rotated position described above with respect to the orientation of the display device 1C, which is located in the center of the three display devices (in Figure 15, this orientation is horizontal to direction X, which is the width direction of the dashboard 7). As a result, the center lines from the front and rear ends of the image display element 25C and the center lines from the front and rear ends of the image display elements 25L and 25R are at an angle to each other. Therefore, in the windshield 3 which has curvature as shown in Figure 16, the virtual image 10L formed by the reflected image light rotates in the direction of the clockwise arrow and becomes horizontal. Also, the virtual image 10R formed by the reflected image light rotates in the direction of the counterclockwise arrow and becomes horizontal.

[0109] As a result of testing with a radius of curvature of approximately 3,000 mm set near the image light reflecting area of ​​the windshield 3, it was found that by creating an angle of approximately 7 to 14° between the center lines from the front and rear ends of the image display element 25C and the center lines from the front and rear ends of the image display elements 25L and 25R, the virtual images 10L and 10R could be viewed almost horizontally. In this case, the display device 1L was rotated counterclockwise with respect to the center of the image display element 25L, and the display device 1R was rotated clockwise with respect to the center of the image display element 25R.

[0110] In this case, when multiple display devices, such as two, four, or five, are mounted on the dashboard, the virtual image can be rotated horizontally by increasing the rotation angle relative to the center of the image display element of the display device that is positioned further to the left and right of the center line of the windshield 3 in the left-right direction of the vehicle. This is due to the fact that the curvature of the windshield 3 gradually increases as it extends to the left and right.

[0111] As shown in Figure 17, the rotated position of the image display element is determined by rotating the image display element 25L around its vertical rotation axis 25v (direction Z), with the center of the image display element 25L being the reference point 25s.

[0112] Figure 18 shows the image display element 25R rotated in the direction of the clockwise arrow, with the center of the image display element 25R being the reference point 25s. In this case, the housing of the display device 1R may not be rotated, and the image display element 25R inside the display device 1R may be assembled and positioned in a rotated position within the display device 1R. In this case, the display device 1R has space inside it so that the image display element 25R can rotate within it.

[0113] The center (reference point 25s) of the video display element 25R is the intersection of the center lines from the left and right ends and the center lines from the front and rear ends of the rectangular video display element 25R, as shown in Figure 18. The center of the video display element 25R may also be the intersection of the diagonals.

[0114] The rotation angle of the image display element 25R is the angle α at which the tangent to the bottom surface 3a at point 3b, where the line extending from the reference point 25s of the image display element 25R toward the front (direction Y) windshield 3 intersects with the bottom surface 3a of the windshield 3, is parallel to the front end or the center line from the front and rear ends of the image display element 25R, as shown in Figure 18.

[0115] As a result, the bottom surface 3a of the windshield 3 and the centerlines of the front and rear ends passing through the reference point of the image display element 25R, or the front and rear ends of the image display element 25R, are positioned in a location that aligns with each other. Similarly, the image display elements 25L and 25C are positioned in a location that aligns with the bottom surface 3a of the windshield 3.

[0116] Furthermore, when the display element of such a display device is assembled to the dashboard 7 of the vehicle 2, it is positioned along the windshield 3. In addition, after assembly, the display element or display device equipped with a display element may be made movable or rotatable relative to the windshield 3, allowing for adjustment of its position to align with the windshield 3.

[0117] Figure 19 is a top view showing the video display elements 25L, 25C, and 25R of the display devices 1L, 1C, and 1R. Display device 1C is positioned relative to the display device in Figure 8, shifted in the direction of the forward arrow (direction Y), with respect to the center of the video display element 25C. Therefore, the display device 1C, which includes the video display element 25C, is assembled and installed in the shifted position. The installation position of the display device 1C can also be adjusted after assembly.

[0118] The reference point of the central display device 1C is located in front of the reference points of the left and right display devices, meaning that the central display device 1C is located in front of the left and right display devices. Therefore, in a windshield 3 having curvature as shown in Figure 20, the virtual image 10C formed by the reflected image light is located in the direction of the downward arrow. In other words, the misalignment between the virtual image 10C of the displayed image and the virtual images 10L and 10R in the vertical direction (direction Z) is eliminated. That is, the positions of the display devices 1L, 1C, 1R, or the image display elements 25L, 25C, 25R are adjusted and arranged so that the height of the emission position and the optical axis of the image light reflected from the windshield 3 are in approximately the same direction.

[0119] Figure 21 is a cross-sectional view illustrating the distortion of the virtual image 10C in a windshield 3 having an aspherical shape with a predetermined curvature. The image light 13L emitted from the display device 1L is reflected by the light ray reflecting portion 50L of the windshield 3. The image light 13R emitted from the display device 1R is reflected by the light ray reflecting portion 50R of the windshield 3. Since the windshield 3 has a symmetrical curvature, the light ray reflecting portion 50L and the light ray reflecting portion 50R are located at the same height.

[0120] Furthermore, the image light 13C emitted from the central display device 1C at the newly moved position is reflected by the light ray reflecting section 50C of the windshield 3. As a result, the light ray reflecting section 50C of the image light is located below (direction Z) and in front (direction Y) of the light ray reflecting sections 50R and 50L, resulting in a smaller positional difference g in the height direction as shown in Figure 11. Therefore, the virtual images 10L, 10C, and 10R appear favorably when viewed from the viewpoint 14.

[0121] Figure 22 is a top view showing the image display elements 25L, 25C, and 25R of the display devices 1L, 1C, and 1R. Display device 1L is positioned rotated in the direction of the counterclockwise arrow relative to the display device in Figure 8, with the center of the image display element 25L as the reference point. Display device 1R is positioned rotated in the direction of the clockwise arrow relative to the display device in Figure 8, with the center of the image display element 25R as the reference point. Display device 1C is positioned moved in the direction of the forward arrow (direction Y) relative to the display device in Figure 8, with the center of the image display element 25C as the reference point. In this way, the three display devices 1L, 1C, and 1R are assembled and installed in their rotated or moved positions. The installation positions of display devices 1L, 1C, and 1R can also be adjusted after assembly.

[0122] In this way, the in-vehicle system 300 is positioned so that the three display devices, namely the image display elements 25L, 25C, and 25R, are aligned with the bottom surface 3a of the windshield 3, when the display devices 1L and 1R are rotated and the display device 1C is moved forward in direction Y. With this arrangement, as shown in Figure 23, the virtual image 10L formed by the reflected image light on the curvatured windshield 3 rotates in the direction of the clockwise arrow and becomes horizontal. Specifically, by setting a radius of curvature of approximately 3,000 mm when viewed in the horizontal direction of the vehicle near the image light reflecting part of the windshield 3 and verifying this, the virtual image 10L became approximately horizontal when the display device 1L was rotated counterclockwise by a range of approximately 5 to 15° with respect to the center of the image display element 25L. In addition, the virtual image 10R formed by the reflected image light rotates in the direction of the counterclockwise arrow and becomes horizontal. Specifically, in the same environment as the verification environment, rotating the display device 1L clockwise by approximately 5 to 15° with respect to the center of the video display element 25R resulted in the virtual image 10L becoming nearly horizontal. Furthermore, the virtual image 10C formed by the reflected video light moved in the direction of the downward arrow, and the positions corresponding to each reference point became horizontal at the same height. Specifically, in the same environment as the verification environment, moving the display device 1C forward in the direction Y by approximately 20 to 40 mm resulted in the display center position of the virtual image 10C becoming the same height as the display center positions of the virtual images 10L and 10R.

[0123] As described above, the in-vehicle system 300 adjusts the position of the display device 1C or the video display element 25C so that the virtual image 10C moves in the direction of the downward arrow, thereby making it horizontal with respect to the virtual images 10L and 10R. However, the in-vehicle system 300 may also adjust the position of the display devices 1R, 1L or the video display elements 25R, 25L so that the virtual images 10L and 10R move upward, thereby making them horizontal with respect to the virtual image 10C at the same height.

[0124] The downward and upward movement of the virtual image in the in-vehicle system varies depending on the type of vehicle 2. In the case of vehicle 2 in Figure 4, it is preferable that the virtual image is displayed in a range of +5° to -10° when viewed from viewpoint 14. In the case of vehicle 5, the virtual image is displayed in a wider range than in vehicle 4, preferably in a range of +5° to -30° when viewed from viewpoint 14.

[0125] Figure 24 shows an example of virtual images 10L, 10C, and 10R after distortion has been adjusted for display on the windshield 3. Virtual image 10L displays entertainment information such as a music playlist. Virtual image 10C displays map and navigation information. Virtual image 10R displays vehicle speed and direction indicator information.

[0126] In Figure 24, when virtual images 10L, 10C, and 10R are displayed, the windshield 3 has curvature, but the virtual images are displayed horizontally without distortion. In particular, the virtual image 10R projected from the right-side display device 1R is displayed at the same horizontal height as the virtual image 10C projected from the central-side display device 1C, and the right and left edges of the virtual image 10R are also displayed at the same horizontal height, eliminating distortion of the displayed content.

[0127] In this way, by simultaneously displaying virtual images with optimized distortion and height, for example, the height of the direction indicated by the nearest direction indicator icon 33a of the virtual image 10R and the height positions of the vehicle icon 32a, destination icon 32b, and route display 32c on the map displayed by the virtual image 10C become correct.

[0128] In other words, when viewed horizontally, the height of the acute angle to the left of the triangular mark indicated by the nearest direction indicator icon 33a is located between the vehicle icon 32a and the destination icon 32b, closer to the destination icon 32b. In other words, the nearest direction indicator icon 33a is intended to point to the route display 32c closer to the destination icon 32b.

[0129] Therefore, the direction indicated by the nearest direction indicator icon 33a of the virtual image 10R indicates that the vehicle intends to pass through the intersection and proceed to the left, rather than turning left at the intersection near the vehicle icon 32a, making it easier to understand the direction in which vehicle 2 is moving. Although the reference point for the display devices 1L, 1C, and 1R is the center of the video display element, the reference point may also be the location of the video display element corresponding to a predetermined display content that clarifies the position of the virtual image in the height direction (for example, the nearest direction indicator icon 33a of the virtual image 10R).

[0130] Even when multiple display devices, such as two, four, or five, are installed on the dashboard, the virtual images can be viewed favorably by adjusting the installation positions of the display devices in the same way as when installing three display devices. For example, in a layout where two display devices are placed on the left and right sides of the vehicle's center, each image display element is positioned along the bottom surface 3a of the windshield 3. In addition, by positioning the two central display devices in front of the two left and right display devices, the positional difference g of each light-reflecting part when viewed in the cross-sectional direction is reduced, allowing each virtual image to be viewed favorably.

[0131] Figure 25 shows a virtual image (display image) from the video display element of the display device shown in Figure 22. The display devices 1L, 1C, and 1R that display video project video light IL, IC, and IR as the principal rays (for example, the center of the video light that is the brightest light) of the video light 13 (see Figure 4). The video light IL, IC, and IR are reflected by the light ray reflection region 3c, which reflects the principal rays of video light, within the display area 5 of the windshield 3 made of transparent glass or the like, to form a display image as virtual images 10L, 10C, and 10R that are visible in front of the driver 140. The virtual image may also be called a display image, optical image, video, etc.

[0132] Multiple display devices 1L, 1C, and 1R are positioned on the dashboard 7 of vehicle 2. The image light from the display devices projects reflected image light IL, IC, and IR onto the windshield 3. However, this projected light does not sufficiently project towards the observation point of the driver 140 of vehicle 2, and the driver 140 may not be able to see at all.

[0133] The image light from the center of the image display element 25L of the display device 1L in Figure 25 is reflected by the light reflection area 3c of the display area 5 inside the windshield 3 and projects the main ray image light IL towards the driver 140. At this time, the main ray image light IL is misaligned with the observation direction DL from the driver 140's observation point of view, which is the observation direction of the virtual image 10L, which is the displayed image.

[0134] The misalignment between the video light IL and the observation direction DL is a misalignment θL. Similarly, the misalignment between the video light IC and the observation direction DC is a misalignment θC, and the misalignment between the video light IR and the observation direction DR is a misalignment θR. These misalignments θL, θC, and θR are due to the position of the display device and the bending of the windshield 3.

[0135] When the driver 140 of vehicle 2 is driving from the right-hand seat (right-hand drive), the deviation θL is greater than the deviation θC, and the deviation θC is greater than the deviation θR. Thus, the deviations θL, θC, and θR between the principal ray image light IL, IC, IR and the virtual images 10L, 10C, 10R as displayed images from the observation viewpoint are greater as the displayed image moves away from the viewpoint in the left-right direction of vehicle 2 X.

[0136] Figure 26 is a detailed diagram showing the virtual image (display image) from the video display element of the display device shown in Figure 22. The projected principal ray, the image light IL, has some degree of spread. That is, the area around the image light IL has ambient light and brightness. The image light IL, as the principal ray, is the brightest, and the area around the image light IL becomes darker the further you move away from it. This spread of the image light with a predetermined ambient light is the spread angle θLW, θRW. When the range of the image light spread angle is near the viewpoint of the driver 140's observation point, some of the image light is projected, and the driver 140 can see a virtual image.

[0137] The video light IR from the video display element 25R in Figure 26 has a divergence angle θRW. The divergence angle θRW is near the viewpoint of the driver 140's observation point. Also, the deviation θR between the video light IR and the observation direction DR is small. Therefore, the driver 140 can see the virtual image. On the other hand, the video light IL from the video display element 25L has a divergence angle θLW. However, the divergence angle θLW is not near the viewpoint of the driver 140's observation point, and is outside the observation point. Also, the deviation θL between the video light IL and the observation direction DL is large. Therefore, it becomes difficult for the driver 140 to see the virtual image. Thus, when the range of the divergence angle of the video light is large relative to the deviation between the observation direction and the video light, the virtual image (displayed image) can be seen.

[0138] Figure 27 is a detailed diagram showing the virtual image (display image) from the image display element of the display device. In Figure 27, the divergence angle θLW of the image light from the image display element 25L of the display device 1L in Figure 26 is widened to a divergence angle θLW2. In other words, the image display element 25L, which is further away from the viewpoint, has a wider angle of image light than the image display element 25R.

[0139] The display device 1L is equipped with a wide-angle light diffusion sheet in the optical path. For example, the display device 1L uses an anisotropic diffusion sheet, which has a wide angle of diffusion relative to the longitudinal direction of the image display element 25L, installed inside the display device 1L, i.e., below the image display element 25L, as a light diffusion sheet. By providing this light diffusion sheet, light emitted upward from the light diffusion sheet at a wide angle diffuses the image light in the longitudinal direction of the image display element 25L via the image display element 25L, is reflected in the light reflection region 3c, and further diffuses to the left and right of the vehicle 2. That is, the image light becomes spread at a divergence angle θLW2 in the left-right direction (direction X) of the vehicle 2. As a result, the driver 140 can see the virtual image 10L which becomes the display image.

[0140] On the other hand, the intensity of the widened-angle video light decreases relatively compared to before the widening. That is, the concentrated light is dispersed to the periphery, making the displayed image darker. For this reason, the display device 1L increases the output of the light source 20, etc., to make the brightness of the emitted video light approximately equal to or equal to the brightness of the video light from the display device 1R, etc. Alternatively, the display device 1R, etc. decreases the output of the light source 20, etc., to make the brightness of the emitted video light approximately equal to or equal to the brightness of the video light from the display device 1L. However, increasing the brightness of the video light generates heat, which may cause thermal degradation of the video display elements 25L such as LCDs and resin components within the display device 1L. For this reason, the display device 1L sets the power of the light source 20, etc. to a predetermined upper limit.

[0141] Furthermore, the display device 1L has a widening angle θLW2, which extends beyond the observation viewpoint, resulting in increased light loss and potentially causing variations in the brightness of the image light. For this reason, the display device 1L is equipped with a predetermined and appropriate light diffusion sheet. In addition, to prevent diffuse reflection of the widened image light, an anti-reflection member is provided in the interior of the vehicle 2.

[0142] Figure 28 is another diagram showing the virtual image (display image) from the video display element of the display device. Figure 29 is a detailed view of the video display element 25L of the display device 1L in Figure 28. Figure 30 is an explanatory diagram of the video light of the display device 1L in Figure 29. Figure 31 is an explanatory diagram of the optical direction conversion panel of the display device 1L in Figure 28. Figure 32 is an explanatory diagram of the optical direction conversion panel of the display device 1R in Figure 28.

[0143] Figure 28 shows that, instead of the light diffusion sheet used in Figure 27, a linear Fresnel lens is used to increase the brightness of the virtual image (display image) as seen from the driver's 140 observation viewpoint. The display device 1L of the vehicle 2 is equipped with, for example, a light direction conversion panel 26 (see Figure 31), which is a linear Fresnel lens made of sheet or resin molding, to convert the direction of the video light IL to the driver's 140 observation viewpoint and obtain video light CL. As a result, the display device 1L can increase the brightness of the virtual image 10L of the display image as seen from the observation viewpoint.

[0144] Furthermore, display device 1C is equipped with an optical direction conversion panel 26 to obtain video light CC by converting the direction of video light IC to the observation viewpoint. Similarly, display device 1R is equipped with an optical direction conversion panel 26 to obtain video light CR by converting the direction of video light IR to the observation viewpoint. In this way, display devices 1L, 1C, and 1R obtain the light rays of video light CL, CC, and CR that are concentrated at a single predetermined position, which is the observation viewpoint of the driver 140.

[0145] Figure 29 shows details of the image display element 25L of the display device 1L in Figure 28. The display device 1L obtains image light CL by changing the direction of image light IL through the optical direction conversion panel 26 (see Figure 31) and the image display element 25L located in the display panel. That is, when the optical direction conversion panel 26 is not installed, the light projected from the center o of the direction X1 and direction Y1 of the image display element 25L is reflected at point a in the light ray reflection region 3c of the windshield 3 and projects image light IL as image light towards the driver 140. This image light IL is the arrow oa from point o to point a and its extension in Figure 30.

[0146] Furthermore, when the light direction conversion panel 26 is installed, the light projected from the center o of the image display element 25L is reflected at point c in the light ray reflection region 3c of the windshield 3, projecting image light CL to the driver 140. Point c in the light ray reflection region 3c of the windshield 3 lies on the observation direction DL, which connects the viewpoint and the center of the virtual image 10L. Point c is the intersection of the image light from the center o to point c and the observation direction DL. This image light CL is the arrow oc from point o to point c and its extension in Figure 30.

[0147] Furthermore, the optical direction conversion panel 26, which is a linear Fresnel lens, has a groove 26b (see Figure 31). The linear Fresnel shape of the optical direction conversion panel 26, that is, the direction gd of the groove 26b formed on the optical direction conversion panel 26 (Figure 29), is direction Y1. In other words, the direction gd of the groove 26b is direction Y1, which is parallel to the direction (AA in the figure) of the emitted light IL, which is projected from the center o of the image display element 25L, reflected at point a in the light reflection region 3c, and emitted towards the driver 140.

[0148] The groove direction gd is also the direction Y1 on the plane of the image display element 25L that is perpendicular to the longitudinal direction (BB in the figure) of the display panel 11 having the image display element 25L, or the direction Y1 on the plane of the image display element 25L that is parallel to the short direction of the image display element 25L.

[0149] Thus, in the display device 1L of Figure 28, the optical direction conversion panel 26 converts the optical direction of the image light IL, which is deflected away from the viewpoint due to the bending of the windshield 3. The optical direction of the image light IL is converted toward the viewpoint by the amount of the deviation θL between the observation direction DL and the image light IL, resulting in image light CL that is coaxial with the optical axis connecting the viewpoint and the image center of the virtual image 10L, which is the displayed image. In other words, the intensity peak of the image light CL, which is the principal ray, is directed toward the viewpoint, making the displayed image of the virtual image 10 visible without excessively spreading the image light.

[0150] Figure 31 is a diagram of the optical direction conversion panel 26 of the display device 1L. The prism inclination angle ηL of the prism portion 26a of the optical direction conversion panel 26, which acts as a linear Fresnel lens, is the angle at which the image light IL (arrow oa) emitted from the display device 1L is converted to image light CL (arrow oc) by a bending angle ψL, as shown in Figures 29 and 30. Multiple prism portions 26a of the optical direction conversion panel 26 are formed linearly in the direction X1, and each prism inclination angle ηL is the same. The groove 26b of the optical direction conversion panel 26 is formed along the direction Y1.

[0151] Light projected onto the optical direction conversion panel 26, which is a linear Fresnel lens, is directed by the prism section 26a of the optical direction conversion panel 26. Furthermore, light passing through the optical direction conversion panel 26 may be directed further by the plane on the side of the optical direction conversion panel 26 facing the image display element 25L.

[0152] Light is redirected by passing through the optical direction conversion panel 26, and the light is projected from the optical direction conversion panel 26. The projected light is projected onto the image display element 25L, which is opposite the optical direction conversion panel 26 with a gap between them, and the image display element 25L projects image light CL towards the windshield 3 (see Figure 4) at a bending angle ψL. The optical direction conversion panel 26 and the image display element 25L may be opposite each other without a gap.

[0153] Figure 32 is a diagram of the optical direction conversion panel 26 of the display device 1R. The prism inclination angle ηR of the prism portion 26a of the optical direction conversion panel 26, which is a linear Fresnel lens, is the inclination angle at which the image light IR emitted from the display device 1R is converted into image light CR by a bending angle ψR. The light projected onto the linear Fresnel lens of the display device 1R is converted in direction by the optical direction conversion panel 26, as in Figure 31, and projected from the image display element 25R. At this time, the image light CR is projected toward the windshield 3 (see Figure 4) at a bending angle ψR.

[0154] The bending angle ψL of the display device 1L in Figure 31 is greater than the bending angle ψR of the display device 1R in Figure 32. That is, the prism inclination angle ηL of the prism section 26a of the display device 1L is greater than the prism inclination angle ηR of the prism section 26a of the display device 1R. This is because, as shown in Figure 28, the deviation θL between the image light IL of the principal ray and the observation direction of the virtual image 10L as a displayed image from the observation viewpoint becomes larger as the displayed image moves away from the viewpoint in the left-right direction X of the vehicle 2.

[0155] The prism tilt angle can be changed by changing the depth d, pitch p, and tilt of the prism section 26a. As shown in Figure 32, changing the prism tilt angle involves changing the depth d of the prism section 26a as seen in direction Z, and the pitch p of the prism section 26a as seen in direction X1. In other words, the prism tilt can be changed by keeping the pitch p constant and changing the depth d, or by keeping the depth d constant and changing the pitch p.

[0156] When the pitch p is constant and the depth d is changed, this can be achieved, for example, by creating an appropriate prism shape that takes transfer into consideration when manufacturing the linear Fresnel lens, which is the optical direction conversion panel 26, by resin molding. When the pitch p is constant and the bending angle ψR is reduced, the depth d of the vertical wall portion becomes smaller, and the component incident on the small vertical wall portion decreases. In the large vertical wall portion, the incident component increases, which can cause total internal reflection and generate unwanted light that deviates from the bending angle. Therefore, a prism tilt angle ηR with a reduced depth d of the vertical wall portion can suppress the generation of unwanted light. In addition, when retrofitting the linear Fresnel lens to the display device 1R, the possibility of the tip of the prism portion 26a coming into contact with other components of the display device 1R, such as the light guide portion 23 in Figure 45A, can be suppressed.

[0157] When the depth d is constant and the pitch p is changed, the depth d is kept small to suppress the generation of unwanted light, and by further increasing the bending angle ψR, the pitch p becomes finer, and the projected light (display image) can be made highly accurate.

[0158] The prism tilt of the linear Fresnel lens in a display device can be adjusted in two ways: by keeping the pitch p constant and changing the depth d, or by keeping the depth d constant and changing the pitch p. When using multiple linear Fresnel lenses, these methods may be combined.

[0159] In Figure 28, the display devices 1L, 1C, and 1R are resin-molded linear Fresnel lenses using a method in which the pitch p is constant and the depth d is changed. Alternatively, any one of the display devices 1L, 1C, or 1R may be resin-molded using a method in which the depth d is constant and the pitch p is changed.

[0160] Furthermore, in Figure 28, even when the rightmost display device 1R is to the right of the driver's viewpoint with a negative shift θR, the linear Fresnel lens can adjust its bending angle ψ and prism tilt angle η to match the shift θR, thereby increasing the brightness of the virtual image of the display as seen from the observation viewpoint.

[0161] In Figure 28, the misalignment θR of the display device 1R is zero when it is positioned 11° to the right of the line of sight. However, the position of the display device 1R where the misalignment θR is zero is located outside the dashboard 7 of the vehicle 2. Therefore, the bending angle ψR of the linear Fresnel lens of the display device 1R must be the bending angle when the display device 1R is positioned inside the dashboard 7.

[0162] When the misalignment θL between the image light IL of the display device 1L and the observation direction DL is 0, for example, when the display device 1L has a windshield 3 with a curvature such that the misalignment θL is 0, the display device 1L does not need to be provided with a linear Fresnel lens.

[0163] Furthermore, the vicinity of the image light reflection area (light ray reflection area 3c) of the display area 5 of the windshield 3 in Figure 28 has a radius of curvature of approximately 3,000 mm when viewed in the direction X (horizontal direction) of the vehicle 2. The linear Fresnel lens is made of PMMA with a refractive index of approximately 1.494, and the pitch p of the prism section 26a is fixed at a constant 1 mm.

[0164] The prism inclination angle ηL of the prism section 26a of display device 1L is greater than the prism inclination angle ηC of the prism section 26a of display device 1C. Also, the prism inclination angle ηC of the prism section 26a of display device 1C is greater than the prism inclination angle ηR of the prism section 26a of display device 1R. In other words, vehicle 2, when viewed from the driver's (140) viewpoint in direction X, increases the prism inclination angle of the prism section 26a of the linear Fresnel lens installed on the display device that is farther from the viewpoint. Conversely, vehicle 2 decreases the prism inclination angle of the prism section 26a of the linear Fresnel lens installed on the display device that is closer to the viewpoint. By using linear Fresnel lenses with such different prism inclination angles, each display device concentrates light rays towards the driver's viewpoint, resulting in high brightness for each virtual image (display image).

[0165] The prism inclination angle ηL of the prism section 26a of the display device 1L is preferably in the range of 20 to 40°, and particularly preferably in the range of 31.8 to 35.8°. Similarly, the prism inclination angle ηC of the prism section 26a of the display device 1C is preferably in the range of 20 to 40°, and particularly preferably in the range of 29 to 35°. Furthermore, the prism inclination angle ηR of the prism section 26a of the display device 1R is preferably in the range of 20 to 40°, and particularly preferably in the range of 21 to 26°.

[0166] Furthermore, when mounting the display device of vehicle 2 to a vehicle with a different curvature of the windshield 3, changing the linear Fresnel lens provided in the display device allows for the commonization of other components of the display device, leading to cost reduction.

[0167] Similarly, when the driver 140 of vehicle 2 is driving from the left-hand seat (left-hand drive) or the center seat (center-hand drive), each display device can adjust the bending angle ψ and prism tilt angle η to match the misalignment, thereby increasing the brightness of the virtual image of the displayed image as seen from the observation point.

[0168] Vehicle 2 has three display devices: display device 1L, display device 1C, and display device 1R. Vehicle 2 may also have two, four, five, or more display devices.

[0169] Figure 33 shows two display devices 1L and 1R positioned symmetrically on either side of the center of the windshield 3, with a gap between them. In this case, the display devices 1L and 1R can be configured with settings for bending angles ψ and prism inclination angles η, etc., in accordance with the misalignments θL and θR, thereby increasing the brightness of the virtual image of the displayed image as seen from the observation viewpoint.

[0170] Figure 34 shows two display devices 1L and 1R positioned symmetrically on either side of the center of the windshield 3, with the gap between them narrowed. In this case, the display devices 1L and 1R can be configured with settings for the bending angle ψ, prism inclination angle η, etc., in accordance with the misalignment θL and θR, thereby increasing the brightness of the virtual image of the displayed image as seen from the observation viewpoint.

[0171] Figure 35 shows two display devices 1L and 1R positioned asymmetrically with respect to the center of the windshield 3. In this case, the display devices 1L and 1R can be configured with settings for bending angles ψ and prism inclination angles η, etc., in accordance with the misalignments θL and θR, thereby increasing the brightness of the virtual image of the displayed image as seen from the observation viewpoint.

[0172] Figure 36 is another diagram showing the virtual image (display image) from the video display element of the display device. Figure 37 is a detailed view of the video display element 25L of the display device 1L in Figure 36. Figure 38A is an explanatory diagram of the video light of the display device 1L in Figure 36. Figure 38B is another explanatory diagram of the video light of the display device 1L in Figure 36.

[0173] The display devices 1L, 1C, and 1R in Figure 36 differ from those in Figure 28 in the direction of the groove 26b of the linear Fresnel lens which serves as the optical direction conversion panel 26. Similar to the display device in Figure 28, the display device in Figure 36 can increase the brightness of the virtual image 10L of the displayed image as seen from the observation viewpoint.

[0174] Display device 1L in Figure 36 is equipped with a linear Fresnel lens optical direction conversion panel 26 (see Figure 39) to obtain image light CL by converting the direction of image light IL to the observation viewpoint of the driver 140. Display device 1C is equipped with an optical direction conversion panel 26 to obtain image light CC by converting the direction of image light IC to the observation viewpoint. Similarly, display device 1R is equipped with an optical direction conversion panel 26 to obtain image light CR by converting the direction of image light IR to the observation viewpoint. In this way, display devices 1L, 1C, and 1R obtain the light rays of image light CL, CC, and CR which are concentrated to the observation viewpoint of the driver 140, and can increase the brightness of each virtual image (image display) as seen from the observation viewpoint.

[0175] Figure 37 shows details of the display device 1L in Figure 36. The display device 1L obtains video light CL by changing the direction of video light IL through the light direction conversion panel 26 (see Figure 39) and the video display element 25L in the display panel 11. That is, when the light direction conversion panel 26 is not installed, the light projected from the center o of the video display element 25L is reflected at point a in the light ray reflection region 3c of the windshield 3 and projected as video light IL towards the driver 140. This video light IL is the arrow oa from point o to point a and its extension in Figures 38A and 38B.

[0176] Furthermore, when the optical direction conversion panel 26 is installed, the light projected from the center o of the image display element 25L is reflected at point c in the light ray reflection region 3c of the windshield 3, projecting image light CL to the driver 140. This point c is the intersection of the observation direction DL, which connects the viewpoint and the center of the virtual image 10L, and the light ray reflection region 3c on the inner surface of the windshield 3. This image light CL is the arrow oc from point o to point c and its extension in Figures 38A and 38B. Therefore, the angle between the image light IL and the image light CL is the bending angle ψL at which the light direction conversion panel 26 changes direction.

[0177] Furthermore, the linear Fresnel lens, which serves as the optical direction conversion panel 26 (see Figure 39), has a groove 26b. The linear Fresnel shape of the linear Fresnel lens, that is, the direction gd of the groove 26b formed on the optical direction conversion panel 26, is the direction on the optical direction conversion panel 26 that is perpendicular to the arrow oc connecting the center o of the image display element 25L to point c in Figure 37. In other words, the linear Fresnel shape is the direction perpendicular to the arrow oc projected from the center o of the image display element 25L to point c in the light reflection region 3c of the windshield 3 when the optical direction conversion panel 26 is installed.

[0178] Furthermore, in the vehicle 2 of Figure 36, the display devices are arranged symmetrically in direction X with respect to the center of the windshield 3. The downward angle from which each virtual image (display image) is viewed toward the direction Z is the same. For example, the angle formed by the center of the video display element 25L of the display device 1L, point c in the light reflection area 3c of the windshield 3, and the viewpoint is approximately equal to the angle formed by the display devices 1C and 1R.

[0179] Therefore, by keeping the prism tilt angle η of the light direction conversion panel 26 constant and changing the Fresnel shape insertion angle with respect to the image display elements 25L, 25C, and 25R, i.e., the direction gd of the groove 26b, the display device can convert the direction of the image light toward the viewpoint direction.

[0180] Therefore, as shown in Figure 36, by changing the Fresnel shape insertion angle of the identically shaped optical direction conversion panel 26, the same configuration of display devices can be used as display devices 1L, 1C, and 1R. For this reason, each display device can be used by rotating a sheet-type optical direction conversion panel 26 having the same prism shape. Alternatively, the sheet-type optical direction conversion panel 26 may be cut to match the shape of the display device to match the Fresnel shape insertion angle.

[0181] In this way, the optical direction conversion panel 26 converts the optical direction of the image light IL, IC, and IR, which are deflected away from the viewpoint due to the bending of the windshield 3, toward the viewpoint by the deviation θL, θC, and θR from the observation directions DL, DC, and DR. As a result of the optical direction conversion, the image light IL, IC, and IR become the image light CL, CC, and CR, which are coaxial with the line connecting the viewpoint and the center of the virtual image 10L, 10C, and 10R. Therefore, the intensity peaks of the image light CL, CC, and CR are directed toward the viewpoint, resulting in high brightness without excessively spreading the image light, and the driver 140 can see the displayed image.

[0182] In other words, for a vehicle 2 having a windshield 3 with different curvature in the left-right direction (direction X), the only change required is to change the insertion angle of the linear Fresnel lens provided in the display device, i.e., the direction gd of the groove 26b. Therefore, vehicle 2 does not need to install display devices with different components or linear Fresnel lenses with different prism inclination angles, allowing for the commonization of display device components and leading to cost reduction.

[0183] Figure 39 is a diagram of the configuration of the optical direction conversion panel 26 of the display device 1L shown in Figure 36. The prism inclination angle ηL of the prism portion 26a of the linear Fresnel lens that forms the optical direction conversion panel 26 is the inclination angle at which the image light IL (arrow oa) emitted from the display device 1L is converted to the image light CL (arrow oc), as shown in Figure 37. Multiple grooves 26b are formed in a straight line in the prism portion 26a of the linear Fresnel lens, and each prism inclination angle ηL is the same.

[0184] Light projected onto the linear Fresnel lens is redirected by the prism portion 26a of the linear Fresnel lens. Furthermore, light passing through the linear Fresnel lens may be redirected again by a plane on the image display element 25L side of the linear Fresnel lens.

[0185] The light projected from the linear Fresnel lens, whose direction is changed by the linear Fresnel lens, is projected onto the image display element 25L which is separated from the linear Fresnel lens by a gap, and the image light CL is projected from the image display element 25L towards the windshield 3 (see Figure 4) at a bending angle ψL.

[0186] In Figure 36, the display devices 1L, 1C, and 1R have the same prism inclination angles ηL, ηC, and ηR of the prism portion 26a of the linear Fresnel lens. Therefore, the bending angles ψL, ψC, and ψR from the linear Fresnel lens are also the same. However, the Fresnel shape insertion angle ε of the linear Fresnel lens installed in the display devices 1L, 1C, and 1R are different, meaning the direction gd of the groove 26b is different. The direction gd of the groove 26b, i.e., the linear Fresnel shape, is perpendicular to the direction of the arrow oc projected from the center o of the image display element 25L to point c in the light reflection region 3c of the windshield 3 when the optical direction conversion panel 26 is installed.

[0187] Figures 40A and 40B are explanatory diagrams of the optical direction conversion panel 26 of the display device 1L. The display device 1L has an image display element 25L attached to it, and a linear Fresnel lens, which serves as the optical direction conversion panel 26, is installed below the image display element 25L, which is inside the display device 1L. At this time, the direction gd of the groove 26b of the linear Fresnel lens, i.e., the Fresnel shape insertion angle εL, is set in the range of 0° < εL < +90°, with the direction parallel to the short side of the image display element 25L being 0° and the direction parallel to the long side being +90°. Similarly, the display device 1C is set with a Fresnel shape insertion angle εC, and the display device 1R is set with a Fresnel shape insertion angle εR.

[0188] In Figure 36, when the driver 140 of vehicle 2 is in the right-hand seat (right-hand drive), the Fresnel shape insertion angle εL of the left-side display device 1L is smaller than the Fresnel shape insertion angle εC of the display device 1C which is more central to the display device 1L. Also, the Fresnel shape insertion angle εC is smaller than the Fresnel shape insertion angle εR of the display device 1R which is to the right of the display device 1C.

[0189] Vehicle 2 has three display devices: display device 1L, display device 1C, and display device 1R. However, vehicle 2 may have two, four, five, or more display devices.

[0190] Furthermore, in Figure 36, for example, even when the rightmost display device 1R has a negative shift θR to the right of the driver's viewpoint 140, the linear Fresnel lens can set the Fresnel shape insertion angle εR to match the shift θR, thereby increasing the brightness of the virtual image of the display image as seen from the observation viewpoint.

[0191] Furthermore, when the misalignment θR of the display device 1R is 0, for example, when the windshield 3 has a curvature such that the misalignment θR is 0, the display device 1R does not need to be provided with a linear Fresnel lens.

[0192] In Figure 36, the vicinity of the image light reflection area (light ray reflection area 3c) of the display area 5 of the windshield 3 has a radius of curvature of approximately 3,000 mm when viewed in the direction X (horizontal direction) of the vehicle 2. The linear Fresnel lens is made of PMMA with a refractive index of approximately 1.494, and the pitch p of the prism section 26a is fixed at a constant 1 mm. The prism inclination angle η is 10° to 30°. By setting the Fresnel shape insertion angle ε of the linear Fresnel lens to a range of 35 to 80° (εL < εC < εR), each virtual image is concentrated at the observation viewpoint, and the virtual image of the displayed image as seen from the observation viewpoint can be made brighter.

[0193] Furthermore, when mounting the display device of vehicle 2 to a vehicle with a different curvature of the windshield 3, changing the Fresnel shape insertion angle ε of the linear Fresnel lens provided in the display device allows for the commonization of other components of the display device, leading to cost reduction.

[0194] Similarly, when the driver 140 of vehicle 2 is driving from the left-hand seat (left-hand drive) or the center seat (center-hand drive), each display device can adjust the Fresnel shape insertion angle ε according to the misalignment, thereby increasing the brightness of the virtual image of the displayed image as seen from the observation point.

[0195] Figure 41 is a detailed view of Figure 4, showing an example of a configuration in which the display device 1 is mounted on the vehicle 2. Figure 42 shows details of the light guide unit 23 within the display device 1. The display device 1 in Figure 6 is positioned so as to be embedded in the dashboard 7 in Figure 41. The image light from the display device 1 is projected toward the windshield 3 and reflected by the windshield 3.

[0196] The direction of light emission from the display device 1 is determined by the shape of the reflective surface and the inclination 23b of the reflective surface, which reflects the light rays from the polarization conversion element 22 of the light reflective section 23a of the light guide section 23 in Figure 42 and directs them toward the display panel 11. The direction of light emission is, for example, perpendicular to the display panel 11, or within a range of approximately ±20° relative to the vertical direction of the display panel 11.

[0197] When the image light is emitted perpendicularly to the display panel 11, the inclination 23b of each reflective surface of the light reflecting part 23a of the light guide unit 23 is set within the range of 30 to 40°. Furthermore, when the light is emitted at an angle of 20° from the vertical towards the light source 20 relative to the display panel 11, the inclination 23b of each reflective surface of the light reflecting part 23a of the light guide unit 23 is set within the range of 40 to 50°.

[0198] By setting the direction of light emission from the display panel 11 in this way, the display devices 1L, 1C, and 1R in Figures 25 to 27 can emit light images toward the driver 140 of the vehicle 2.

[0199] Furthermore, a display device with a wide-angle image light, as shown in Figure 27, can be realized by changing the diffusion characteristics of the diffuser plate 24. Note that there is a space between the display panel 11 and the diffuser plate 24. This space prevents heat generated by the light source 20 (which acts as a heat source) and heat absorbed by its surrounding components from being transferred to the display panel 11, which is a heat-degradable component.

[0200] In the vehicle 2 shown in Figure 41, such as a passenger car, it is preferable to ensure a downward angle of 2° or more for the virtual image (display image) projected through the inclined windshield 3, looking down in the direction Z. For this reason, the display device should be mounted on the front side of the vehicle 2 in the direction Y, rather than on the driver's side 140 of the dashboard 7.

[0201] On the other hand, inside the dashboard 7, other components such as pipes, ducts, and fixing mechanisms for the windshield 3 are located near the front, i.e., the bottom surface 3a of the windshield 3, making it difficult to create space for mounting a display device. For this reason, the display device needs to have a minimal protrusion of its housing from the front of the vehicle 2.

[0202] As shown in Figure 41, the display device is positioned so that the light source 20, which protrudes beyond the edge of the display panel 11, faces the driver 140, and the tip of the light guide 23 opposite to the light source 20 faces the windshield 3. In other words, the light source 20, reflective mirror 21, polarization conversion element 22, etc. of the backlight section 12 are positioned on the driver 140 side, not the front side of the vehicle 2.

[0203] Thus, even if there are other components on the front side of the vehicle 2, far from the driver 140 side below the dashboard 7, space for the display device 1 can be secured, and the display panel 11 of the display device 1 can be installed near the bottom surface 3a of the front windshield 3. Alternatively, the display panel 11 of the display device 1 may be tilted downward from the front towards the driver side, rather than horizontal, to further avoid other components when installing the display device 1.

[0204] Figure 43 is another diagram showing an example of the light source structure of the display device. Figure 43 has a different configuration of the light source unit 12, which is the backlight part of Figure 6. Figure 44 is a detailed diagram showing another example of how the display device of Figure 43 is mounted on a vehicle 2. In Figure 44, the display device 1 of Figure 43 is positioned so as to be embedded in the dashboard 7.

[0205] The image light from the display device 1 is projected toward the windshield 3 and reflected by the windshield 3. The direction of emission of the image light from the display device 1 is set by the shape and inclination of the reflective surface of the light reflective surface 23a of the light guide unit 23. In addition, the light ray is reflected back toward the light source 20 by the light reflective surface 23a of the light guide unit 23.

[0206] The diffuser plate 24 is installed parallel to the display panel 11. The diffusion characteristics of the diffuser plate 24 can be changed to widen the angle of the display device's image light. Because the display panel 11 and the diffuser plate 24 are positioned parallel to each other, the thickness of the display device 1's housing in direction Z2 can be reduced compared to the thickness of a display device where the diffuser plate 24 is tilted relative to the display panel 11 (see Figure 6). This positioning allows for a smaller display device 1, reducing the space it occupies within the dashboard 7.

[0207] The display device emits video light from the display panel 11 in a direction that reflects it back toward the light source 20, allowing the display device's housing to conform to the shape of the top surface of the dashboard 7. This type of mounting reduces the space between the top surface of the dashboard and the display device.

[0208] In Figure 44, the direction of emission of the image light is tilted 35° to 40° toward the light source 20 from the vertical direction of the display panel 11. Due to this tilt, the space occupied within the dashboard 7 by the mounting of the display device is reduced by 36% compared to the space in Figure 6. The inclination of each reflective surface of the light reflective part 23a of the light guide part 23 at this time is in the range of 55° to 75°.

[0209] Furthermore, the size of the light guide unit 23 is smaller than the size of the light guide unit 23 in Figure 6. Here, the light source unit 12 in Figure 6 emits image light from the display panel 11 at a nearly vertical angle, as shown in Figure 41. For this reason, the width of the reflective surface of the light guide unit 23 is large enough to cover most of the display panel 11.

[0210] On the other hand, the light source unit 12 in Figure 43 emits image light from the display panel 11 at an angle θ tilted from the vertical. The angle θ of the direction of emission of the image light is tilted 35° to 40° toward the light source 20 from the vertical direction of the display panel 11. As a result, the width of the reflective surface of the light guide unit 23 on the light source 20 becomes smaller. That is, the angle θ obtained by folding the display panel 11 toward the light source 20 from the vertical direction becomes the cosine of the width L of the display panel 11, and the width of the reflective surface of the light guide unit 23 relative to the width L of the display panel 11 becomes smaller.

[0211] Thus, the light guide portion 23 in Figure 43 is smaller than the display panel 11. Furthermore, the light guide portion 23 in Figure 43 is smaller than the light guide portion 23 in Figure 6. As a result, the amount of material used during the molding of the light guide portion 23 in Figure 43 and the amount of reflective film deposition material for the light reflecting portion 23a are reduced, thereby lowering material costs.

[0212] On the other hand, the display device 1 reflects the image light back towards the light source 20, so that the image light does not interfere with the polarization conversion element 22, the light source 20, and the cooling mechanism of its mounting substrate (a mechanism located on the side opposite to the direction of light emission of the light source 20).

[0213] In other words, the light guide unit 23 is positioned away from the polarization conversion element 22. Therefore, the light source unit 12, which is the backlight unit in Figure 43, is larger in the width direction Y2 compared to the light source unit 12 in Figure 6. The distance between the polarization conversion element 22 and the light guide unit 23 of the display device 1 in Figure 43 is about 10 mm longer than that of the display device 1 in Figure 6.

[0214] Furthermore, the display device 1 controls the divergence angle of the light rays by adjusting the shape of the reflective surface 23a of the light guide unit 23 and the inclination of the reflective surface, thereby setting the diffusion angle of the diffuser plate 24 to 10°.

[0215] Note that the coordinate system (X, Y2, Z2) in Figure 43 is based on the arrangement of the display device 1 in Figure 44. Multiple LED light sources 20 are installed along direction X, and light rays are projected from the light sources 20 in direction Z2. The projected light rays are reflected by the reflective mirror 21 having a collimating element and projected in direction Y2. The light rays projected in direction Y2 pass through the polarization conversion element 22, are focused by the light reflecting part 23a of the light guide unit 23, and projected onto the diffuser plate 24 and the display panel 11, and an optical image is emitted from the display panel 11.

[0216] By setting the direction of emission of video light to the display panel 11 in this way, the display devices 1L, 1C, and 1R in Figures 25 to 27 can emit video light toward the driver 140 of the vehicle 2.

[0217] Figure 45A shows an example of a side view of the light source structure of a display device. Figure 45B shows an example of a front view of the light source structure of a display device. Figure 45C shows an example of a perspective view of the light source structure of a display device.

[0218] The display device in Figure 45A is the display device in Figure 43 further equipped with an optical direction conversion panel 26, which is a linear Fresnel lens. As shown in Figure 45A, the optical direction conversion panel 26 is installed in the optical path between the light guide 23 and a diffuser plate 24, such as a diffuser film having a diffuser element. The optical direction conversion panel 26 may also be installed between the light source 20 and the display panel 11 having the image display element 25. By installing the optical direction conversion panel 26 upstream of the diffuser plate 24 in the optical path, the optical ray direction can be changed by the linear Fresnel lens before diffusion by the diffuser plate 24, making it easier to control the bending angle ψ of the light ray (image light). The optical direction conversion panel 26 may also be installed in the optical path between the image display element 25 and the windshield 3.

[0219] Note that the coordinate system (X, Y2, Z2) in Figures 45A, 45B, and 45C is based on the coordinate axes of the display device 1 in Figure 44. Multiple LED light sources 20 are installed along direction X, and light rays are projected from the light sources 20 in direction Z2. The projected light rays are reflected by a reflective mirror 21 having a collimating element and projected in direction Y2. The light rays projected in direction Y2 pass through the polarization conversion element 22 and are focused by the light reflection part 23a of the light guide part 23 and projected onto the prism part 26a of the linear Fresnel lens (see Figures 31 and 32).

[0220] Furthermore, the light rays projected from the linear Fresnel lens pass through the diffuser plate 24, which has a gap between it and the linear Fresnel lens, and project image light through the display panel 11 at a bending angle ψ as shown in Figure 45B. The Fresnel shape of the linear Fresnel lens, i.e., the direction gd of the groove 26b, is aligned with direction Y2 as shown in Figure 45C. Therefore, the light rays emitted from the light guide unit 23 and incident on the linear Fresnel lens, which is the light direction conversion panel 26, do not bend on the plane between direction Y2 and direction Z2, but bend on the plane between direction X and direction Z2. Consequently, image light is projected from the display panel 11 at a bending angle ψ, and image light with the light direction converted by the displacement θ between the windshield 3 and the viewpoint can be obtained.

[0221] By setting the direction of emission of video light to the display panel 11 in this way, the display devices 1L, 1C, and 1R in Figure 28 can emit video light toward the driver 140 of the vehicle 2.

[0222] Figure 46A is another diagram showing an example of a side view of the light source structure of the display device. Figure 45B is another diagram showing an example of a front view of the light source structure of the display device. Figure 45C is another diagram showing an example of a perspective view of the light source structure of the display device. As shown in Figure 46A, the linear Fresnel lens, which is the optical direction conversion panel 26, only needs to be located between the light source 20 and the display panel 11 having the image display element 25 in the optical path, and is installed between the light guide 23 and the diffuser plate 24, such as a diffusion film having a diffusion element.

[0223] The display device, by installing a linear Fresnel lens upstream of the diffuser plate 24 in the optical path, can change the direction of the light rays with the linear Fresnel lens before diffusion by the diffuser plate 24, making it easier to control the bending angle ψ of the light rays (image light). Alternatively, the linear Fresnel lens may be installed between the image display element 25 and the windshield 3 in the optical path.

[0224] The coordinate systems (X, Y2, Z2) in Figures 46A, 46B, and 46C are coordinate axes based on the arrangement of the display device 1 in Figure 44. Multiple LED light sources 20 are installed along direction X, and light rays are projected from the light sources 20 in direction Z2. The projected light rays are reflected by a reflective mirror 21 having a collimating element and projected in direction Y2.

[0225] Light rays projected in direction Y2 pass through the polarization conversion element 22, are focused by the light reflection section 23a of the light guide section 23, and are projected in direction Z2, which is perpendicular to the plane between directions X and Y2, onto the prism section 26a (see Figure 39) of the linear Fresnel lens, which is the optical direction conversion panel 26. The projection direction of the light rays from the light guide section 23 to the optical direction conversion panel 26 in Figure 46A is different from the projection direction of the light rays in Figure 45A. That is, the light projected onto the linear Fresnel lens, which is the optical direction conversion panel 26 in Figure 46A, is perpendicular to the plane from which the image light of the display panel 11 is emitted. Also, the light projected onto the linear Fresnel lens is perpendicular to the opposing plane of the linear Fresnel lens that faces the display panel 11.

[0226] Thus, light projection onto the linear Fresnel lens is performed by a light source unit 12, which is a backlight unit that is incident perpendicularly to the outer plane of the display panel 11 having the image display element 25L. As a result, the length of the display panel 11 in direction Y2 can be shortened to about the length of the light guide unit 23, thus enabling miniaturization of the display device. In addition, the light rays reflected by the light guide unit 23 in Figure 46A are not blocked by the polarization conversion element 22, etc., and the distance between the polarization conversion element 22 and the light guide unit 23 can be narrowed, further enabling miniaturization of the display device.

[0227] Light rays projected from the linear Fresnel lens pass through the diffuser plate 24, which has a gap between it and the linear Fresnel lens, and project image light through the display panel 11, bending on a plane between directions X and Z2 as shown in Figure 46B. The direction gd of the Fresnel shape of the linear Fresnel lens, i.e., the direction of the formed groove 26b, is perpendicular to the arrow oc that projects from the center o of the image display element 25L to point c in the light reflection region 3c of the windshield 3 when the light direction conversion panel 26 is installed as shown in Figure 37. The insertion angle of the linear Fresnel lens at this time is the Fresnel shape insertion angle ε. Therefore, light rays emitted from the light guide unit 23 and incident on the linear Fresnel lens, which is the light direction conversion panel 26, bend on a plane between directions Y2 and Z2, and bend on a plane between directions X and Z2, as shown in Figure 46C. Consequently, image light is projected from the display panel 11 at a bending angle ψ, and image light with the light direction converted by the displacement θ between the windshield 3 and the viewpoint can be obtained.

[0228] By setting the direction of emission of video light to the display panel 11 in this way, the display devices 1L, 1C, and 1R in Figure 36 can emit video light toward the driver 140 of the vehicle 2.

[0229] The technology according to this embodiment can display good projected images (including virtual images). The technology according to this embodiment can prevent traffic accidents by providing a vehicle equipped with a display device that reduces the driver's eye movement and contributes to supporting safe driving. In this way, the technology according to this embodiment contributes to the United Nations' Sustainable Development Goal (SDG) 3, "Good Health and Well-being." [Explanation of Symbols]

[0230] 1, 1L, 1C, 1R: Display device, 2: Vehicles, 3: Windshield, 3a: Bottom part, 3c: light reflection area, 5:Display area, 7: Dashboard, 8L, 8R: A-pillar, 10, 10L, 10C, 10R: virtual image, 11: Display panel, 12: Light source section, 13, 13L, 13L, 13R: Video light, 14: Perspective, 20: Light source, 21: Reflective mirror, 22: Polarization conversion element, 23: Light guide section, 23a: light reflecting part, 24: Diffuser, 25, 25C, 25L, 25R: Image display element, 26: Optical direction conversion panel, 26a: Prism section, 26b: groove, 100: Controller, 140: Driver, 200: Video display unit, 300: In-vehicle systems, 400: External equipment, 410: Terminal device, 500: Network, 600: Relay station, 700: Server.

Claims

1. In a display device that displays a virtual image on a vehicle's windshield, The display device comprises a light source that emits light, a light direction conversion panel that converts the direction of the light emitted from the light source, and a display panel that emits the light image converted by the light direction conversion panel.

2. In the display device according to claim 1, The optical direction conversion panel is a display device in which a linear Fresnel lens has multiple prism sections formed in a straight line.

3. In the display device according to claim 2, A display device in which the prism inclination angles of the prism sections are all the same.

4. In the display device according to claim 1, The system further comprises a light guide that reflects the aforementioned light, and a diffuser plate that disperses the light incident on the light guide. The optical direction conversion panel is a display device installed in the optical path between the light guide and the diffuser plate.

5. In an in-vehicle system that displays a virtual image, The vehicle has a display device according to any one of claims 1 to 4, The in-vehicle system comprises multiple display devices, wherein the video light emitted by each of the display devices is converted by the light direction conversion panel of each display device and focused toward a predetermined position for the driver.

6. In the in-vehicle system according to claim 5, An in-vehicle system in which the angle of refraction of light emitted from each of the aforementioned optical direction conversion panels is different, thereby converging the video light emitted from each of the aforementioned display devices toward the predetermined position.

7. In the in-vehicle system according to claim 6, An in-vehicle system in which the prism tilt angle of each of the aforementioned optical direction conversion panels is different, resulting in different bending angles for each of them.

8. In the in-vehicle system according to claim 7, An in-vehicle system in which the display device that is away from the predetermined position has a larger prism tilt angle than the display device that is closer to the predetermined position.

9. In the in-vehicle system according to claim 7, An in-vehicle system in which the linear Fresnel-shaped grooves of the optical direction conversion panel are oriented perpendicular to the longitudinal direction of the display panel.

10. In the in-vehicle system according to claim 6, An in-vehicle system in which each of the aforementioned optical direction conversion panels has a different linear Fresnel groove shape, resulting in different bending angles for each panel.

11. In the in-vehicle system according to claim 10, An in-vehicle system in which the light emitted to the light direction conversion panel is perpendicular to the plane from which the image light of the display panel is emitted.

12. The in-vehicle system according to claim 5 and a controller that controls the video light by linking each of the display devices, vehicle.

Images