Image display device

Abstract

To provide an image display device which can display a virtual image with two layers, which has a structure reduced in size, and which contributes to "3 Good Health and Well-Being" in the sustainable development goals.SOLUTION: An image display device is mounted in a vehicle so as to display a virtual image by projecting image light to a windshield. The image display device includes a display panel and a branch part. The display panel emits the image light. The branch part is arranged at an emission surface side of the display panel so as to branch the image light emitted from the display panel into a plurality of optical paths.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a video display device. [Background technology]

[0002] A known example of an image display device is a head-up display (HUD) that is mounted on a vehicle and projects and displays various information onto the windshield, etc. Patent Document 1 discloses a HUD device that forms multiple display areas using multiple image forming units. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2024-007661 Summary of the Invention [Problem to be solved by the invention]

[0004] When a vehicle displays a virtual image in two layers, for example, a large-volume display device is mounted in the vehicle. However, since the dashboard layout differs from vehicle to vehicle, it is preferable to miniaturize the device. Therefore, there is a problem in providing a structure that can display a virtual image in two layers while also achieving miniaturization. [Means for solving the problem]

[0005] According to a first aspect of the present invention, there is provided the following image display device. This image display device displays a virtual image by projecting image light onto a vehicle windshield. This image display device includes a display panel and a branching unit. The display panel emits image light. The branching unit is disposed on the emission surface side of the display panel and branches the image light emitted by the display panel into multiple optical paths.

[0006] According to a second aspect of the present invention, there is provided the following image display device. This image display device displays a virtual image by projecting image light onto a vehicle windshield. This image display device includes a display panel and a branching unit. The display panel emits image light. The branching unit reflects a portion of the image light emitted by the display panel multiple times, thereby branching the image light into image light traveling along a first optical path and image light traveling along a second optical path. [Effects of the Invention]

[0007] According to the present invention, it is possible to display a virtual image in two layers and provide a compact structure. Note that problems, configurations, and effects other than those described above will become clear from the following description of the embodiment of the invention. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of an outline of a vehicle equipped with a display device. [Figure 2] FIG. 2 is a diagram illustrating an example of a configuration provided in a vehicle. [Figure 3] FIG. 1 is a diagram illustrating an example of a configuration of a display device. [Figure 4] FIG. 1 is a diagram illustrating an example of a configuration of a display device. [Figure 5] FIG. 1 is a diagram for explaining an overview of an example of a conventional technique. [Figure 6] FIG. 1 is a diagram for explaining an overview of an example of a conventional technique. [Figure 7] FIG. 1 is a diagram for explaining an overview of an example of a technique related to the present embodiment. [Figure 8] FIG. 10 is a diagram illustrating an example of a branching portion. [Figure 9] 10A and 10B are diagrams for explaining an example of installation of a 1 / 2 polarizing plate and an example of displaying a virtual image. [Figure 10] FIG. 10 is a diagram illustrating how a virtual image is viewed by a driver. [Figure 11] FIG. 10 is a diagram for explaining an example of installation of a ½ polarizing plate. [Figure 12]FIG. 12 is a diagram for explaining an example of video display in the arrangement shown in FIG. 11(b). [Figure 13] 10A and 10B are diagrams for explaining an example of installation of a 1 / 2 polarizing plate and an example of displaying a virtual image. [Figure 14] 10A and 10B are diagrams for explaining a configuration example of a branching section. [Figure 15] 10A and 10B are diagrams for explaining a configuration example of a branching section. [Figure 16] 10A and 10B are diagrams for explaining a configuration example of a branching section. [Figure 17] 10A and 10B are diagrams for explaining a configuration example of a branching section. [Figure 18] FIG. 10 is a diagram for explaining in detail the measures against sunlight. [Figure 19] FIG. 10 is a diagram for explaining in detail the measures against sunlight. [Figure 20] FIG. 10 is a diagram for explaining the degree of freedom of layout. [Figure 21] FIG. 10 is a diagram for explaining an example of a layout. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The embodiment is an example for explaining the present invention, and for clarity of explanation, appropriate omissions and simplifications have been made. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

[0010] In order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0011] When there are multiple components with the same or similar functions, they may be described using the same reference numeral with different subscripts. When there is no need to distinguish between these multiple components, the subscripts may be omitted.

[0012] In the embodiments, processing performed by executing a program may be described. Here, a computer executes the program using a processor (e.g., a CPU or a GPU) and performs processing defined by the program using storage resources (e.g., a memory) and interface devices (e.g., a communication port). Therefore, the entity performing the processing by executing the program may be the processor. Similarly, the entity performing the processing by executing the program may be a controller, device, system, computer, or node having a processor. The entity performing the processing by executing the program may be any computing unit, and may include a dedicated circuit that performs specific processing. Here, the dedicated circuit may be, for example, an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or a CPLD (Complex Programmable Logic Device).

[0013] A program may be installed on a computer from a program source. The program source may be, for example, a program distribution server or a computer-readable storage medium. When the program source is a program distribution server, the program distribution server may include a processor and storage resources for storing the program to be distributed, and the processor of the program distribution server may distribute the program to be distributed to other computers. In addition, in an embodiment, two or more programs may be realized as one program, or one program may be realized as two or more programs.

[0014] In the embodiment, with respect to the vehicle and the driver, the horizontal direction is the left-right direction, the lateral direction of the vehicle, or the width direction of the vehicle, the vertical direction is the up-down direction or longitudinal direction of the vehicle, and the vertical direction perpendicular to the lateral direction of the vehicle is the front-rear direction of the vehicle or the direction of travel of the vehicle. As shown in Fig. 1, the width direction of the vehicle may be described as the X direction, the front-rear direction of the vehicle as the Y direction, and the up-down direction of the vehicle as the Z direction.

[0015] FIG. 1 is a diagram showing an overview of a vehicle. As shown in FIG. 1, the vehicle 2 includes a display device 1 and a controller 100. The vehicle 2 also includes an in-vehicle system including these components. In this in-vehicle system, an in-vehicle network is implemented, and the controller 100 can transmit and receive data or information to and from the display device 1 and components described below via an information transmission path. In the in-vehicle system, for example, a CAN (Controller Area Network), an in-vehicle Ethernet, a LIN (Local Interconnect Network), etc. are implemented.

[0016] The in-vehicle system can also communicate with the outside of the vehicle via a communication device. Examples of communication with the outside of the vehicle include direct communication and indirect communication. In the direct communication method, the 760 MHz band, 5.9 GHz band, etc., are used as international ITS (Intelligent Transport System) communication bands for direct communication between vehicles, roads, vehicles, and pedestrians. In contrast, indirect communication uses mobile phone bands other than 5.9 GHz for indirect communication via a mobile carrier network. The in-vehicle system can transmit and receive data or information to, for example, a server connected to a network via an access point or relay station on the network. The in-vehicle system may communicate with information terminals carried by other vehicles or pedestrians, or with infrastructure such as terminals installed on the road where the vehicle is traveling. An example of road-to-vehicle communication is receiving traffic congestion information and weather information using radio beacons or optical beacons.

[0017] Vehicle information 4, which is an example of data or information acquired by an in-vehicle system, includes, for example, speed information, gear information, steering angle information, lamp illumination information, external light information, distance information, infrared information, engine ON / OFF information, camera image information, acceleration gyro information, GPS information, navigation information, vehicle-to-vehicle communication information, road-to-vehicle communication information, pedestrian-to-vehicle communication information, and in-vehicle sensor information such as Lidar (Light Detection and Ranging). Camera image information includes in-vehicle camera image information and outside-vehicle camera image information. GPS information includes current time information, latitude and longitude information. This vehicle information can be acquired, for example, from sensors described below.

[0018] The vehicle information 4 also includes information input by the driver. The driver can input the information using an appropriate device used for inputting information. This device may be a device that is pre-installed in the vehicle. Alternatively, this device may be an external device that can be connected to the in-vehicle system by wire or wirelessly, such as an input device, a tablet, a smartphone, a wearable device such as AR (Augmented Reality) glasses or an HMD (Head Mounted Display), or a personal computer.

[0019] The in-vehicle system can use the acquired data or information to perform various types of control, such as driving control and display control.

[0020] The display device 1 generates image light for displaying information and projects the image light toward a predetermined display area 5 on the windshield 3. As a result, the display device 1 superimposes a virtual image corresponding to the displayed image onto the scenery, for example, so that the driver of the vehicle (from the driver's viewpoint) can view it. Note that in this example, the image light is projected onto the display area on the windshield 3, but the projection unit that projects the image light may be a projection member such as a combiner.

[0021] The controller 100 is an electronic control unit (ECU) mounted in the vehicle 2, and includes, for example, a processing device (e.g., a central processing unit), a storage device, and an input / output device (I / O unit). The storage device can be configured using, for example, a main storage device and an auxiliary storage device. The main storage device is a work area for the processing device, and the processing device stores data in the main storage device and executes data processing. The main storage device is, for example, a RAM (Random Access Memory). The auxiliary storage device is a non-volatile storage device that stores data in a non-volatile manner. The auxiliary storage device is, for example, a ROM (Read Only Memory).

[0022] Data or information is input to the controller 100 via an input / output device and an in-vehicle network. The controller 100 can also control various devices connected to the in-vehicle network via the input / output device and the in-vehicle network.

[0023] For example, vehicle information 4 and information acquired from a server are input to the controller 100 via an input / output device. Then, the controller 100 may control the operation of the display device 1 based on the acquired information.

[0024] The display device 1 may be connected to various sensors mounted on the vehicle 2, devices mounted on the vehicle 2 (for example, a car navigation system), communication devices used for communication with the outside of the vehicle, and the like, to acquire data or information. Then, the display device 1 may use the acquired data or information to generate video light for displaying information and project the video light.

[0025] The display device 1 can omit communication with the controller 100. Here, the display device 1 can acquire data or information from a configuration different from the controller 100 through communication based on, for example, CAN, in-vehicle Ethernet, or the like.

[0026] Alternatively, the controller 100 may generate video data using the acquired data or information, transmit the generated video data to the display device 1, and the display device 1, upon receiving the video data, may generate video light for displaying information based on the video data generated by the controller 100 and project the video light. Alternatively, the controller 100 may not generate video data, but rather the video generation unit may generate the video data and transmit the generated video data to the display device 1. Here, the controller 100 and the display device 1 may communicate based on, for example, FPD-Link III or GMSL (Gigabit Multimedia Serial Link), and the display device 1 may acquire the video data from the controller 100.

[0027] Furthermore, the display device 1 processes the acquired video data for video that requires video processing, and the video processing involves processing related to image distortion correction, color correction, brightness correction, contrast correction, conversion (e.g., decoding), etc. The video data may be stored in advance in a storage device of the controller 100 or the display device 1, or may be processed in real time without being stored in a storage device. When the video data is stored in advance in a storage device of the controller 100 or the display device 1, the stored video data may be changed successively by a system update or a user operation, by wired or wireless means, etc.

[0028] As described above, the display device 1 may be connected to various sensors mounted on the vehicle, devices mounted on the vehicle 2 (for example, a car navigation system), communication devices used for communication with the outside of the vehicle, etc., and may acquire data or information through communication based on CAN, in-vehicle Ethernet, etc. Then, the display device 1 may generate video light for displaying information based on the acquired information, and project the video light.

[0029] Information such as the vehicle information 4 is acquired using devices such as cameras and various sensors, etc. Fig. 2 shows an example in which the controller 100 or a control device is connected to various devices.

[0030] The vehicle speed sensor 901 detects the speed of the vehicle 2 and is used to generate speed information as the detection result. The shift position sensor 902 detects the current gear and is used to generate gear information as the detection result. The steering wheel angle sensor 903 detects the current steering wheel angle and is used to generate steering wheel angle information as the detection result.

[0031] The headlight sensor 904 detects, for example, whether the headlights are on or off. The headlight sensor 904 may also detect the luminance of the headlights when they are on. The headlight sensor 904 is used to generate lamp lighting information, which is the detection result. The vehicle 2 may also be provided with a high / low sensor that detects the high beam or low beam state of the headlights, and the high / low sensor is used to generate information indicating the high beam or low beam. The vehicle 2 may also be provided with a tail lamp sensor (not shown). The tail lamp sensor detects, for example, whether the tail lamps are on or off. The tail lamp sensor may also detect the luminance of the tail lamps when they are on. The tail lamp sensor is used to generate lamp lighting information, which is the detection result. Similarly, although not shown, sensors that detect the on / off and lighting luminance of stop lamps, backup lamps, hazard lamps, and turn signals may also be provided.

[0032] The illuminance sensor 905 and chromaticity sensor 906 detect external light from the vehicle 2 and are used to generate external light information, which is the detection result. The chromaticity sensor 906 may also be used to detect the background color of the projection surface and generate projection surface color information, which is the detection result. The distance measurement 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, which is the detection result. The infrared sensor 908 detects the presence or absence of an object in the vicinity of the vehicle and the distance, etc., and is used to generate infrared information, which is the detection result. The engine start sensor 909 detects whether the engine is on or off and is used to generate on / off information, which is the detection result.

[0033] The vehicle operation switches 911 are various switches operated by the driver or the like, and are used to generate operation information such as ON / OFF of these switches. The vehicle operation switches 911 relate to steering switches, switches on the dashboard, vehicle door switches, switches on the armrest, switches on the center console, and the like.

[0034] The acceleration sensor 912 and gyro sensor 913 detect the acceleration and angular velocity of the vehicle 2 and are used to generate acceleration gyro information that represents the attitude and behavior of the vehicle 2. The temperature sensor 914 detects the temperature inside and outside the vehicle and is used to generate temperature information that is the detection result.

[0035] The wireless transceiver 915 for road-to-vehicle communication generates road-to-vehicle communication information through road-to-vehicle communication between the vehicle 2 and roads, signs, traffic lights, etc. The wireless transceiver 916 for vehicle-to-vehicle communication generates vehicle-to-vehicle communication information through vehicle-to-vehicle communication between the vehicle 2 and other surrounding vehicles. The wired and wireless communication unit 917 for mobile terminal-to-vehicle communication is a device that acquires information by wired communication or wireless communication from a device connected to the LTE network (e.g., a WiFi device). The controller 100 or the control device can acquire information transmitted and received over the LTE network via the wired and wireless communication unit 917 for mobile terminal-to-vehicle communication.

[0036] The GPS receiver 921 generates GPS information by receiving GPS signals from GPS satellites. For example, the current time, latitude, and longitude can be acquired by the GPS receiver 921. The VICS (registered trademark) receiver 922 generates VICS (registered trademark) information by receiving VICS (registered trademark) signals. The VICS (registered trademark) signals here include traffic congestion information and weather information from radio beacons and optical beacons. The GPS receiver 921 and the VICS (registered trademark) receiver 922 may be provided as part of a navigation system.

[0037] 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 camera image information and exterior camera image information. Specifically, the in-vehicle camera 919 is, for example, a camera for a DMS (Driver Monitoring System) that captures the driver's posture, eye position, movement, etc. In this case, the driver's fatigue level, eye position, etc. can be determined by analyzing the captured images.

[0038] The voice of the driver is input to the voice input device 918 and is used to generate voice information. The driver can input operation details via the voice input device 918 by uttering a voice. An audio output device may also be provided. The audio output device is, for example, a device that outputs a voice processed by the controller 100 or a control device.

[0039] The image generating unit 910 may generate image information based on information acquired from each sensor, information from a mobile terminal, information from the Internet, or the like, or may generate image information based on information acquired by the controller 100. Information other than that related to the vehicle includes information from a mobile terminal, information from the Internet, and the like.

[0040] The controller 100 or the control device may transmit and receive data or information via wireless communication, for example, and acquire information necessary for driving. The controller 100 or the control device may acquire information necessary for autonomous driving. The controller 100 or the control device may transmit and receive data or information via wireless communication, for example, and perform update processing of the data or information. The controller 100 or the control device may perform update processing of various data or information (map data, data used for video processing, software, etc.), for example. Such technology is sometimes called OTA (Over the Air) technology.

[0041] Controller 100 may be configured as a function for generating images, in which case image generation unit 910 may be omitted.

[0042] The video generation unit 910 may generate and transmit video data. Here, the video generation unit 910 may include a control unit, and the control unit may perform the processing. Alternatively, the video generation unit 910 may be controlled by the controller 100.

[0043] The controller 100 may acquire signals from various devices and transmit them to the display device 1. The display device 1 may then generate video data based on the received signals and display the video. On the other hand, the controller 100 may transmit video data to the display device 1, and the display device 1 may display the video based on the received video data.

[0044] 2, the display device 1 can directly acquire information without going through the controller 100. The display device 1 may then generate video data based on the acquired information and display the video.

[0045] The various devices in FIG. 2 can be deleted, or other types of devices can be added or replaced with other types of devices as appropriate.

[0046] An example of the configuration of a display device will be described with reference to Fig. 3. In Fig. 3, the display device 1 includes, for example, a microcontroller (MCU) 1010 mounted on a wiring board or the like, a non-volatile memory 1011, a volatile memory 1012, a communication processing unit 1014, a video processing unit 1013, a display driver 1021, a light source driving unit 1022, and a video display unit 200. In the example of Fig. 3, the communication processing unit 1014 is a device equipped with a communication interface, is connected to a transmission path, and communicates main vehicle information 4, but may also function as a control unit of the display device 1. In addition, various types of information (e.g., video information), control signals, etc. may be input to the communication processing unit 1014 from the controller 100 via the transmission path.

[0047] The image processing unit 1013 processes image data that determines the display content of the image to be projected on the display area of ​​Fig. 1, etc., based on the acquired information. For example, communication is performed based on FPD-Link III, GMSL (Gigabit Multimedia Serial Link), etc., and the image processing unit 1013 receives image information or image data generated by the controller 100 or the image generation unit 910 of the vehicle 2. In this case, the image processing unit 1013 does not generate an image, but processes the image received from the vehicle 2. The processing of the image processing unit 1013 includes processes such as image distortion correction and conversion (e.g., decoding).

[0048] The communication processing unit 1014 may be configured to have two types of interfaces. That is, the communication processing unit 1014 may be configured to have an interface dedicated to receiving video information and a communication interface used for communicating other information and data.

[0049] As is widely known, the MCU 1010 includes a processor such as a CPU (Central Processing Unit), memory, and various peripheral functions. Therefore, each block except for the MCU 1010 may be appropriately mounted within the MCU 1010. Furthermore, the display device 1 is not limited to being implemented using the MCU 1010, but may be implemented using an ECU or other semiconductor devices. The control structure shown in FIG. 3 may be, for example, a control unit mounted within the housing of the display device 1, or a control unit mounted outside the housing.

[0050] The non-volatile memory 1011 mainly stores in advance programs executed by the CPU in the MCU 1010, setting parameters used in the processing of each unit in the MCU 1010, specified audio data, video data, etc. The volatile memory 1012 mainly stores acquired information and various data used in the processing of each unit in the MCU 1010 as appropriate.

[0051] 3 may be implemented as a dedicated circuit such as a field programmable gate array (FPGA) etc. In this embodiment, the control device is configured to have a non-volatile memory 1011 and a volatile memory 1012, but the above processing may be performed by a single memory.

[0052] The display driver 1021 drives each display element (pixel) included in the display panel 11 based on the video data. In this way, the image forming unit PGU1 creates and displays an image to be projected onto the display area based on the video data. Specifically, the distortion correction described above corrects image distortion caused by the curvature of the windshield 3 when an image from the display device 1 is projected onto the display area 5, as shown in FIG. 1. The display driver 1021 then drives each display element (pixel) included in the display panel 11 based on the corrected video data. In this way, the image forming unit PGU1 creates and displays an image to be projected onto the display area based on the corrected video data.

[0053] Furthermore, the light source driver 1022 can adjust the light source, and adjusts the brightness of the light source 15 in the image forming unit PGU1. For example, the light source 15 is controlled using the vehicle information 4 received via the communication processor 1014 and the light source driver 1022, which is a driver used to drive the light source.

[0054] Furthermore, the display device 1 may protect the display panel 11 based on external light information from the illuminance sensor 905. That is, in order to prevent the display panel 11 from being burned by sunlight shining on it, the display device 1 may perform an operation to protect the panel from sunlight according to the value of the illuminance sensor 905. More specifically, when the intensity of external light or sunlight acquired by the illuminance sensor 905 is strong and there is a risk of the display panel 11 being burned, the display device 1 reduces the brightness of the light source 15 in the image forming unit PGU1 and suppresses the amount of light from the light source 15 that is incident on the display panel 11, thereby suppressing a rise in temperature of the display panel 11.

[0055] 3, the display device 1 may be configured to display an image using a light source 15 as a backlight for the display panel 11. However, the display device 1 may be configured to omit the light source 15. In other words, the display device 1 may have a mini LED, a micro LED, or the like in the display panel 11, and the pixels themselves may emit light.

[0056] An example of the configuration of the display device will be described with reference to Fig. 4. This example differs from the configuration described with reference to Fig. 3 in that an image is generated inside the display device 1. That is, the image processing unit 1013 is omitted, and the configuration is specialized for displaying an image generated inside.

[0057] The video processing unit 1015 generates data for a display video to be projected onto the display area shown in Fig. 1, etc., based on various types of information acquired from the outside. Note that in this case as well, the communication processing unit 1014 may be configured to include an interface for handling video information and data, and a communication interface for use in communicating other information and data.

[0058] The MCU 1010, non-volatile memory 1011, volatile memory 1012, communication processing unit 1014, display driver 1021, light source driving unit 1022, video display unit 200, etc. are the same as those described above, and therefore description thereof will be omitted.

[0059] Next, an example of the conventional technology will be outlined with reference to Figures 5 and 6. Figure 5 shows a HUD that displays two screens (two layers) using backlight units (12a, 12b) and display panels (11a, 11b), and the optical path of the image light from the HUD.

[0060] Here, there are no optical components such as mirrors or lenses that magnify the image light rays between the display panels (11a, 11b) and the windshield 3. Therefore, in the optical path of the image light, the distance from the windshield 3 to the virtual images (10a, 10b) is approximately equal to the distance from the reflection position of the image light on the windshield 3 to the display panels (11a, 11b). Furthermore, although there is some influence from distortion due to the shape of the windshield, the size of the virtual images (10a, 10b) is the same magnification as the display panels (11a, 11b).

[0061] However, in the structure shown in Fig. 5, in order to make the distances to the virtual images (10a, 10b) different, the display panels (11a, 11b) and backlight units (12a, 12b) are arranged at a distance 21 in the up-down direction and a distance 20 in the front-to-back direction. This results in a problem of an increased size of the HUD. Note that in this description, the up-to-down direction refers to the vertical direction of the display panels (11a, 11b), and the front-to-back direction refers to the horizontal direction of the display panels (11a, 11b).

[0062] 6 shows a HUD that displays two screens (two layers) by differentiating the emission positions of the image light on the display panel 11 (i.e., by dividing the emission positions of each image light into front and back), and the optical path of the image light of the HUD. As in the case of FIG. 5, there are no optical components between the display panel 11 and the windshield 3, and in the optical path of the image light, the distance from the windshield 3 to the virtual images (10a, 10b) is approximately equal to the distance from the reflection position of the image light on the windshield 3 to the emission positions (11a1, 11b1) of the display panel 11. Furthermore, the size of the virtual images (10a, 10b) is also equal to that of the display panel 11, although there is some influence from distortion due to the shape of the windshield.

[0063] However, in the structure shown in Fig. 6, in order to make the distances (optical paths) to the virtual images (10a, 10b) different, the image light for displaying each virtual image (10a, 10b) is emitted at a distance 20 in the front-to-rear direction. This increases the dimensions of the display panel 11 and the backlight unit 12 in the front-to-rear direction, which causes a problem of an increased size of the HUD. Note that the front-to-rear direction in this explanation refers to the horizontal direction of the display panel 11.

[0064] From the above perspective, when the HUD shown in FIG. 5 is mounted in a dashboard, the HUD will have a large volume, including the display panels (11a, 11b) and backlight units (12a, 12b). The HUD shown in FIG. 6 can be made smaller in size (i.e., distance 21) in the up-down direction (the vertical direction of the display panel 11) than the HUD shown in FIG. 5. However, it is not easy to reduce the size in the front-to-rear direction (the horizontal direction of the display panel 11). Therefore, when the HUD shown in FIG. 6 is mounted in a dashboard, the size in the front-to-rear direction (the horizontal direction of the display panel 11) will be large.

[0065] Since the layout of the dashboard varies depending on the vehicle and the space inside the dashboard is limited, it is preferable to reduce the size of the structure by, for example, not providing multiple display panels and making the display panels smaller.

[0066] Next, an example of technology related to this embodiment will be outlined with reference to Fig. 7. To solve the problem of reducing the size of the structure, a branching section is arranged on the image light emission surface side of the display panel 11, which branches the image light emitted by the display panel 11 into multiple optical paths.

[0067] The branching unit is disposed, for example, in the dashboard. In addition, in this embodiment, multiple image forming units are not required, and even when virtual images are displayed in two layers, the display panel does not become large, so the overall size is prevented from becoming large.

[0068] An example of the branching unit will be described with reference to Fig. 8. This branching unit includes a half polarizing plate 110, a quarter polarizing plate 111, reflecting mirrors (112a, 112b), and a polarizing beam splitter 113. In this example, in the branching unit, the quarter polarizing plate 111, the reflecting mirrors (112a, 112b), and the polarizing beam splitter 113 are arranged on the same straight line. Furthermore, the display panel 11 emits image light that displays two virtual images (10a, 10b).

[0069] The half polarizing plate 110 is provided so that image light displaying one of the virtual images 10a and 10b passes through. Therefore, the image light displaying one of the virtual images 10a and 10b is polarization-converted and enters the polarizing beam splitter 113. On the other hand, the image light displaying the other virtual image is not polarization-converted and enters the polarizing beam splitter 113.

[0070] The polarizing beam splitter 113 transmits image light having one of P-polarized light and S-polarized light, and reflects image light having the other polarization. Here, the virtual image 10b is displayed by the image light that has transmitted through the polarizing beam splitter 113.

[0071] The image light reflected by the polarizing beam splitter 113 passes through the 1 / 4 polarizing plate 111, is reflected by the reflecting mirror 112a, and passes through the 1 / 4 polarizing plate again, whereby the polarization is converted. Then, this image light passes through the polarizing beam splitter 113 and is reflected by the reflecting mirror 112b. Then, the virtual image 10a is displayed by the image light reflected by the reflecting mirror 112b.

[0072] In FIG. 8, polarized beam splitter 113 is configured to transmit P polarized light and reflect S polarized light, but as will be explained later, it may be configured to transmit S polarized light and reflect P polarized light.

[0073] According to this configuration, unlike the above-described conventional technology, it is not necessary to consider the interval between the emission positions of the image light for each virtual image (10a, 10b), and therefore it is possible to reduce the size of the display panel 11. Furthermore, according to this configuration, the following effects are achieved.

[0074] <Reducing parts costs> Considering the electronic components that reduce yield due to issues such as missing dots, costs are highly sensitive to increases in the size of the display panel. Furthermore, when a backlight unit is used, the increased size of the backlight unit requires an increased number of light source elements, such as LEDs, to achieve effective light distribution characteristics, which increases the size of the optical components and requires stricter shape precision. Therefore, costs are highly sensitive to increases in the size of the backlight unit. According to this configuration, as described above, the size of the display panel 11 can be reduced. Furthermore, when a backlight unit is provided in the display panel 11, the size of the backlight unit can be reduced. Therefore, according to this configuration, costs can be reduced.

[0075] <Solar heat countermeasures> In a conventional structure, sunlight is incident on the display panel 11, which reduces the lifespan of the display panel 11 due to heat generation. Furthermore, when a backlight unit is used, the backlight is incident on the display panel 11, which reduces the lifespan of the display panel 11 due to heat generation. However, according to the present configuration, a branching unit is arranged on the light exit surface side of the display panel 11 so as to cover the display panel 11, and this branching unit reduces the incidence of sunlight on the display panel 11. Here, as one example, the branching unit may have a structure in which a ¼ polarizing plate 111, a reflecting mirror (112a, 112b), and a polarizing beam splitter 113 are arranged in the same straight line. Therefore, according to the present configuration, the arrangement of the branching unit makes it difficult for sunlight heat to be transmitted to the display panel 11, thereby extending the lifespan of the display panel 11.

[0076] <Improved layout freedom> In this configuration, various optical paths can be formed by adjusting the inclination of the reflecting mirrors (112a, 112b), the position of the reflecting mirror 112b, etc. For example, by positioning the reflecting mirror 112b further toward the rear of the vehicle and using a layout that extends the optical path length, the virtual image 10a can be displayed at a greater distance.

[0077] Next, an example of installing a half polarizing plate on the exit surface side of the display panel will be described with reference to FIG.

[0078] The half polarizing plate 110 may be arranged so as to form an area where the image light passes through the half polarizing plate 110 and an area where the image light does not pass through the half polarizing plate 110. In other words, the half polarizing plate 110 may be arranged so that part of the image light of the entire displayed image passes through.

[0079] 9(a), for example, by disposing half polarizing plates 110 on both sides of the display screen below the display screen, when the display panel 11 displays the image shown in FIG. 9(b), it is possible to display virtual images 10a shown in FIG. 9(c) and 10b shown in FIG. 9(d). Note that in the virtual image 10a, there is no display in region 20a corresponding to the region where the image light passes through the half polarizing plate 110, and in the virtual image 10b, there is no display in region 20b corresponding to the region where the image light does not pass through the half polarizing plate 110.

[0080] In this way, by disposing the 1 / 2 polarizing plate 110 and dividing the image to be displayed, it is possible to display a virtual image over a wide range as seen by the driver 50, as shown in Fig. 10. Note that reference numeral 13 indicates an example of the driver's visual field range.

[0081] It is also possible to dynamically change the display of a virtual image by, for example, moving the half polarizer 110 from the top of the display screen to the bottom of the display screen in synchronization with the image on the display panel 11. For example, the half polarizer 110 may move according to the display position of the image on the display panel 11. That is, for example, when changing the display position of the image in the portion of the display panel 11 that overlaps the half polarizer 100, the half polarizer 110 can be moved so as to overlap with the changed display position, thereby dynamically changing the display of the virtual image.

[0082] Next, with reference to FIG. 11, another example of the placement of the half polarizer on the light-emitting surface side of the display panel will be described.

[0083] 11(a) and (c), the half polarizing plates 110 may be arranged in a continuous rectangular shape with any width at any intervals from the left side of the display screen to the right side of the display screen. Alternatively, as shown in (b) and (d) of the same figure, the half polarizing plates 110 may be arranged in a strip shape from the top to the bottom of the display screen. In other words, the half polarizing plates 110 may be arranged so that a portion of the image light of the entire image display is transmitted.

[0084] Fig. 12 shows an example of image display in the arrangement of half polarizers shown in (b) of Fig. 11. As shown in (a) of Fig. 12, an image relating to one virtual image 10a is displayed directly below the half polarizer 110, and an image relating to the other virtual image 10b is displayed in the gap between the half polarizers 110, thereby displaying virtual images (10a, 10b) as shown in (b) and (c) of the same figure.

[0085] When the 1 / 2 polarizing plate 110 is arranged as shown in (b) of Figure 11, the images of each virtual image (10a, 10b) are displayed alternately in the vertical direction of the display screen, as shown in (a) of Figure 12, but when the 1 / 2 polarizing plate is arranged as shown in (a) of Figure 11, the images of each virtual image (10a, 10b) are displayed alternately in the horizontal direction of the display screen.

[0086] In addition, in the example of Figure 12, the gaps in the polarizing plates are large and the areas where images cannot be displayed are noticeable, but by arranging the 1 / 2 polarizing plate 110 so that the gaps in the 1 / 2 polarizing plate 110 are small, as shown in (c) and (d) of Figure 11, the areas where images cannot be displayed are less noticeable, as shown in (d) and (e) of Figure 12 (virtual images) (10a2, 10b2), and it is possible to display images over a larger area.

[0087] In this example, since there is no need to dynamically move the half polarizer 110 in synchronization with the image, the half polarizer 110 may be directly attached to the display panel 11. In this case, the structure can be simplified.

[0088] Next, with reference to FIG. 13, another example of the placement of the half polarizer on the light-emitting surface side of the display panel will be described.

[0089] 13(a), the half polarizing plate 110 may be freely arranged in any shape, such as a circle or a rectangle, regardless of its size, in accordance with the layout of the content to be displayed in advance. The half polarizing plate 110 may be arranged so as to overlap a portion of the entire display screen that displays predetermined information, such as the time, instruments, or alert information. In other words, the half polarizing plate 110 may be arranged so that part of the image light of the entire displayed image is transmitted.

[0090] 13(b), the display panel 11 displays the entire image, whereby virtual images 10a and 10b are displayed based on the image light that passes through the half polarizing plate 110 and the image light that does not pass through the half polarizing plate 110. For example, when the half polarizing plate is arranged as shown in FIG. 13(a) and the display shown in FIG. 13(b) is performed, virtual image 10a that does not include predetermined displays such as the time, instruments, and alert information is displayed as shown in FIG. 13(c), and virtual image 10b that includes only these predetermined displays is displayed as shown in FIG. 13(d).

[0091] While this type of layout is not suitable for displaying moving images such as movies or television, it allows the driver to see a wide range of specified displays such as the time, instruments, and alert information without crowding them together.

[0092] It is also possible to dynamically change the display of the virtual image by, for example, moving the half polarizing plate 110 to a predetermined display position in synchronization with a predetermined display on the display panel 11. For example, the half polarizing plate 110 may move according to the position of the predetermined display on the display panel 11. That is, for example, when changing the position of the predetermined display in the portion of the display panel 11 that overlaps the half polarizing plate 110, the half polarizing plate 110 can be moved so as to overlap with the changed display position, thereby dynamically changing the display of the virtual image.

[0093] In this example, the half polarizer 110 is disposed at a position on the entire screen where a predetermined display is to be made. However, the half polarizer 110 may also be disposed at a position on the entire screen where a predetermined display is not to be made. Then, the display of the virtual image may be dynamically changed by moving the half polarizer 110 to the position of a display different from the predetermined display in synchronization with the display.

[0094] Next, an example of the configuration of the splitter will be described with reference to FIGS. 14 to 17. FIG. 14 shows an example of the configuration of the splitter and an example of the display position of the virtual image. As shown in FIG. 14, the splitter includes, as an example, a ½ polarizing plate 110, reflecting mirrors (112c, 112d), and polarizing beam splitters (113, 113a). In this splitter, the ¼ polarizing plate is omitted compared to the configuration described above. Also, the reflecting mirrors (112a, 112b) are replaced with reflecting mirrors (112c, 112d), and a polarizing beam splitter 113a is added.

[0095] Polarizing beam splitter 113a is disposed on the optical path of the image light passing through polarizing beam splitter 113, and transmits this image light. Unlike reflecting mirror 112a, reflecting mirror 112c reflects the image light incident from polarizing beam splitter 113 toward reflecting mirror 112d. Reflecting mirror 112d reflects the image light toward polarizing beam splitter 113a. Polarizing beam splitter 113a then reflects this image light in the same direction as the image light passing through polarizing beam splitter 113 and polarizing beam splitter 113a. Then, on windshield 3, each image light is reflected at the same position.

[0096] Thus, at the branching section, a portion of the image light emitted from the display panel 11 passes through the reflecting mirrors (112c, 112d), and the optical path of this image light is longer than that of the image light that passes through the polarizing beam splitter 113. As a result, the virtual image 10a based on the image light that travels through the optical path that passes through the reflecting mirrors (112c, 112d) is displayed at a position farther from the windshield 3 than the virtual image 10b based on the image light that travels through an optical path that does not pass through the reflecting mirrors (112c, 112d).

[0097] Here, since the directions in which each image light travels from the polarized beam splitter 113a to the windshield 3 are approximately the same, and the positions at which each image light is reflected on the windshield 3 are approximately the same, when viewed by the driver 50, the virtual images 10a and 10b overlap, making it possible to provide a three-dimensional display based on each image light.

[0098] The arrangement of the half polarizer 110 can be determined, for example, taking into consideration the three-dimensional shape of the content viewed by the driver 50. The half polarizer 110 may also be moved in synchronization with the display of the content. In this description, the polarizing beam splitters (113, 113a) are configured to transmit P-polarized light and reflect S-polarized light, but the polarizing beam splitters (113, 113a) may also be configured to transmit S-polarized light and reflect P-polarized light.

[0099] 15 to 17 show other configuration examples of the splitter. As shown in Fig. 15, the splitter may have a similar structure to the above-described splitter, and the polarized beam splitter 113 may be configured to transmit S-polarized light and reflect P-polarized light.

[0100] 16, the splitter may include a half polarizing plate 110, a reflecting mirror 112e, and a polarizing beam splitter 113. In this splitter, the image light reflected by the polarizing beam splitter 113 is reflected by the reflecting mirror 112e. Then, virtual images (10a, 10b) are displayed by the image light that passes through the polarizing beam splitter 113 and the image light that is reflected by the reflecting mirror 112e.

[0101] When this splitter is used, the polarization of virtual image 10a and virtual image 10b is different, but the number of reflecting mirrors can be reduced, leading to miniaturization. In this example, upper virtual image 10a based on S-polarized light is displayed, and lower virtual image 10b based on P-polarized light is displayed, but by changing the characteristics of the polarizing beam splitter, upper virtual image 10a based on P-polarized light and lower virtual image 10b based on S-polarized light may be displayed.

[0102] 17, the splitter may be configured to include a half polarizing plate 110, a reflecting mirror 112f, and a polarizing beam splitter 113. The image light reflected by the polarizing beam splitter 113 travels toward the windshield 3, where a virtual image 10b is displayed. The image light transmitted through the polarizing beam splitter 113 is reflected by the reflecting mirror 112f, travels toward the windshield 3, where a virtual image 10a is displayed.

[0103] In this splitter, the orientation of the output surface of display panel 11 is changed to the longitudinal direction of the vehicle (toward the rear of the vehicle in this example), but the number of reflecting mirrors can be reduced, resulting in a more compact system. In this example, upper virtual image 10a based on P-polarized light is displayed, and lower virtual image 10b based on S-polarized light is displayed, but by changing the characteristics of polarizing beam splitter 113, upper virtual image 10a based on S-polarized light and lower virtual image 10b based on P-polarized light may be displayed.

[0104] In addition, an appropriate structure can be selected for the branching section, for example, from the perspective of the layout within the dashboard, improving visibility of the display through polarized sunglasses worn by the driver, and preventing double images due to reflection on the back surface of the windshield 3.

[0105] Next, the effects of the sunlight countermeasures will be described in more detail with reference to Figures 18 and 19. As shown in Figure 18, sunlight 16b from sun 16a shines into the dashboard over a wide range. Therefore, when display panel 11 is placed facing upward in the vehicle, sunlight 16b from a wide range enters the light-emitting surface of display panel 11, resulting in a shortened lifespan due to solar heat.

[0106] 19, by arranging a branching section on the light-emitting surface side of the display panel 11, it is possible to prevent sunlight 16b from directly reaching the display panel 11. In other words, measures to reflect / absorb sunlight 16b can be taken at a location away from the display panel 11, so heat is less likely to be transmitted to the display panel 11. As a result, it is possible to protect the display panel 11 from the heat of sunlight.

[0107] Next, with reference to FIG. 20, the degree of freedom in the layout will be described in more detail. A layout in which the display position of the virtual image is adjusted can be realized by adjusting the tilt of the mirrors, adjusting the distance between the reflecting mirrors (112a, 112b), and the like. For example, a layout that lengthens the distance between the reflecting mirrors (112a, 112b) lengthens the optical path of the image light that displays the virtual image 10a, allowing the virtual image 10a to be displayed at a greater distance from the driver. In this way, by extending the optical path length of the image light, the virtual image can be displayed at a greater distance. Furthermore, by adjusting the tilt of the reflecting mirror 112b, the reflection position of the image light on the windshield 3 can be changed, thereby adjusting the position of the virtual image 10a.

[0108] Next, another example of the layout will be described with reference to Fig. 21. In the above example, the branching section is disposed on the light-emitting surface side of the display panel 11, but the branching section may have a structure as shown in Fig. 21, for example.

[0109] As shown in FIG. 21, this branching section includes half polarizing plates (110, 110a), reflecting mirrors (112g, 112h, 112i), and a polarizing beam splitter 113. The reflecting mirror 112g reflects the image light reflected by the polarizing beam splitter 113 downward. The reflecting mirror 112h reflects the image light reflected by the reflecting mirror 112g backward. The reflecting mirror 112i reflects the image light reflected by the reflecting mirror 112h upward toward the windshield 3. Then, the virtual image 10a is displayed. Here, compared to the above layout, the optical path of the image light that displays the virtual image 10a is longer, and therefore the virtual image 10a is displayed at a greater distance.

[0110] In the above, a layout in which the display position of the virtual image 10a is adjusted only by extending the optical path length in the front-back direction (Y direction) has been described. However, in this layout, the optical path length is extended in the up-down direction (Z direction) to adjust the display position of the virtual image 10a. In this manner, a branching layout that adjusts the optical path length in the up-down direction may be realized. Note that a branching layout that extends the optical path length in the horizontal direction may be realized by arranging a reflecting mirror that reflects the image light in the horizontal direction (X direction).

[0111] Furthermore, a polarizing plate may be placed on the optical path to polarize the light as desired to be reflected onto the windshield 3. As an example, a ½ polarizing plate 110a may be placed between the reflecting mirror 112h and the reflecting mirror 112i.

[0112] As an example, an image display device may be provided that is mounted on a vehicle 2 and displays a virtual image by projecting image light onto a windshield 3, and that includes a display panel 11 that emits image light, and a branching section that is arranged on the emission surface side of the display panel 11 and branches the image light emitted by the display panel 11 into multiple optical paths.

[0113] Furthermore, including the explanations of Figures 14 and 21, as an example, an image display device may be provided that is mounted on a vehicle 2 and displays a virtual image by projecting image light onto a windshield 3, and that includes a display panel 11 that emits image light, and a branching section that reflects a portion of the image light emitted by the display panel 11 multiple times to branch the image light into image light traveling along a first optical path and image light traveling along a second optical path.

[0114] In the image display device, as an example, the branching section may be configured to include, as shown in FIG. 21, a polarized beam splitter 113 onto which the image light emitted from the display panel 11 is incident, a first reflecting mirror 112g onto which the image light reflected by the polarized beam splitter 113 is incident and which reflects the image light downward, a second reflecting mirror 112h onto which the image light reflected by the first reflecting mirror 112g is incident and which reflects the image light backward, and a third reflecting mirror 112i onto which the image light reflected by the second reflecting mirror 112h is incident and which reflects the image light towards the windshield 3.

[0115] In the image display device, the splitter may include, for example, a first polarizing beam splitter 113, a first reflecting mirror 112c, a second reflecting mirror 112d, and a second polarizing beam splitter 113a, as shown in Fig. 14. Here, the image light emitted from the display panel 11 is incident on the first polarizing beam splitter 113. The image light reflected by the polarizing beam splitter 113 is incident on the first reflecting mirror 112c, which reflects the image light upward. The image light reflected by the first reflecting mirror 112c is incident on the second reflecting mirror 112d, which reflects the image light to the second polarizing beam splitter 113a. The second polarizing beam splitter 113a transmits the image light that has passed through the first polarizing beam splitter 113, and reflects the image light reflected by the second reflecting mirror 112d in the same direction as the image light that has passed through the first polarizing beam splitter 113.

[0116] Although the embodiments have been described above, the present invention is not limited to the above-described embodiments and includes various modifications and equivalent configurations within the spirit of the appended claims. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, for example, other configurations may be added, deleted, or replaced with part of the configuration of the embodiment.

[0117] The display panel 11 and the branching portion may be arranged, for example, so as to fit within approximately the lower half of the space within the dashboard.

[0118] The mechanism for moving the half polarizing plate 110 in response to the display of the image can be configured as appropriate. For example, the control unit of the display device 1 may control this mechanism to move the half polarizing plate 110 in response to a change in the display position.

[0119] A mechanism for changing the orientation of the reflecting mirrors may be provided, and this mechanism may be configured appropriately. For example, the control unit of the display device 1 may acquire the operation content input by the user and change the orientation of the reflecting mirrors (112b, 112e, 112f, 112i) that reflect the image light toward the windshield 3, thereby adjusting the display position of the virtual image 10a.

[0120] The polarizing beam splitters (113, 113a) can have a plate-type structure, for example. Although half-polarizing plates (110, 110a) and quarter-polarizing plates 111 are used as examples of polarization conversion elements, other polarization conversion elements may be used as long as they operate in the same manner as above. The configurations may be distinguished by adding terms such as "first" and "second."

[0121] Furthermore, by using the technology according to the above-described embodiment, necessary information can be displayed more appropriately by miniaturizing the device and displaying virtual images in two layers. This makes it possible to provide an image display device that contributes to safe driving, etc., and thereby helps to reduce traffic accidents. Furthermore, it is possible to contribute to "Good health and well-being" - goal 3 of the Sustainable Development Goals (SDGs) advocated by the United Nations. [Explanation of symbols]

[0122] 1 Display device 11 Display panel 110 1 / 2 polarizer (polarization conversion element) 111 1 / 4 polarizer 112a Reflecting mirror 112b Reflecting mirror 113 Polarizing Beam Splitter (Beam Splitter)

Claims

1. An image display device that displays a virtual image by projecting image light onto a windshield of a vehicle, a display panel that emits image light; a branching unit arranged on an exit surface side of the display panel and branching the image light emitted by the display panel into a plurality of optical paths; A video display device comprising:

2. 2. The image display device according to claim 1, The branch portion is a first polarization conversion element through which a part of the image light emitted by the display panel passes and which converts the polarization of the transmitted image light; A video display device characterized by:

3. 3. The image display device according to claim 2, The first polarization conversion element is are arranged on both the left and right sides of the exit surface of the display panel, A video display device characterized by:

4. 3. The image display device according to claim 2, The first polarization conversion element is Rectangular shapes having any width are arranged consecutively at any intervals on the screen of the display panel. A video display device characterized by:

5. 3. The image display device according to claim 2, The first polarization conversion element is is arranged to overlap a predetermined display on the display panel, A video display device characterized by:

6. 4. The image display device according to claim 3, The first polarization conversion element is The display panel is movable from the top to the bottom of the display screen. A video display device characterized by:

7. 6. The image display device according to claim 5, The first polarization conversion element is The display panel is movable to a predetermined display position. A video display device characterized by:

8. 2. The image display device according to claim 1, The emission surface of the display panel is directed upward toward the vehicle. A video display device characterized by:

9. 3. The image display device according to claim 2, The branch portion is a beam splitter that separates the incident image light into image light directed toward the windshield and image light to be reflected based on the polarization component; a first reflecting mirror that reflects the image light reflected by the beam splitter toward the beam splitter; a second polarization conversion element through which the image light reflected by the beam splitter and the image light reflected by the first reflecting mirror are transmitted, thereby converting a polarization component of the image light; a second reflecting mirror that reflects the image light that has been reflected by the first reflecting mirror and then polarization-converted by the second polarization converting element toward the windshield; A video display device comprising:

10. 10. The image display device according to claim 9, In the branching unit, the beam splitter, the first reflecting mirror, the second polarization conversion element, and the second reflecting mirror are arranged on the same straight line. A video display device characterized by:

11. 3. The image display device according to claim 2, The branch portion is a beam splitter that separates the incident image light into image light directed toward the windshield and image light to be reflected based on the polarization component; a reflecting mirror that reflects the image light reflected by the beam splitter toward the windshield; A video display device comprising:

12. 3. The image display device according to claim 2, The branch portion is a beam splitter that separates the incident image light into transmitted image light and image light that is reflected toward the windshield based on the polarization component; a reflecting mirror that reflects the image light transmitted through the beam splitter toward the windshield; A video display device comprising:

13. The image display device according to claim 12, The emission surface of the display panel is directed toward the rear of the vehicle. A video display device characterized by:

14. An image display device that displays a virtual image by projecting image light onto a windshield of a vehicle, a display panel that emits image light; a branching unit that branches a portion of the image light emitted by the display panel into image light traveling along a first optical path and image light traveling along a second optical path by reflecting the portion of the image light multiple times; A video display device comprising:

Images