Display device and vehicle mounted with same

Abstract

A display device according to the present invention is characterized by being provided with a display panel (11) capable of emitting video light to a windshield (3) of a vehicle (2), and a light source (12) emitting light to the display panel (11), wherein the display panel (11) is directed toward the driver (50) side of the vehicle (2), and the display panel (11) is disposed so as to be inclined with respect to the horizontal surface.

Description

Display device and vehicle equipped with said device

[0001] The present invention relates to a display device, a virtual image display device, and a vehicle equipped with the display device.

[0002] BACKGROUND ART Virtual image display devices or head-up displays (HUDs) are known that project image light onto the windshield or the like of an automobile to form a virtual image and display, for example, traffic information such as route information and congestion information, and automobile information such as remaining fuel and coolant temperature.

[0003] Japanese Patent Application Publication No. 3-169752

[0004] The image display unit of the display device is placed, for example, on or inside the dashboard of a vehicle. In this case, external light such as sunlight is reflected by the image display unit and enters the eyebox, resulting in unwanted stray light and deteriorating visibility. To prevent this, it is conceivable to provide a cover around the display device to prevent sunlight from entering, but blocking the optical path of the image light with a cover or the like would make the virtual image invisible, and it is therefore considered difficult to achieve a complete solution.

[0005] Therefore, there is a problem in suppressing the decrease in visibility due to sunlight without blocking the optical path of the image light.

[0006] According to a first aspect of the present invention, there is provided a display device as follows: The display device includes a display panel capable of projecting image light onto a windshield of a vehicle, and a light source that emits light to the display panel. The display panel is oriented toward the driver of the vehicle and is tilted relative to the horizontal plane.

[0007] According to the present invention, by tilting the display panel, it is possible to suppress the deterioration of visibility due to sunlight without blocking the optical path of the image light. Note that problems, configurations, and effects other than those described above will become clear from the description of the following embodiments of the invention.

[0008] 1 is a diagram showing an example of a vehicle equipped with a display device. A diagram showing an example of a device used to acquire vehicle information. A block diagram showing an example of a display device. A block diagram showing an example of a display device. A diagram for explaining an example of a countermeasure against sunlight. A diagram showing an example of the structure of a display device. An enlarged view showing a light reflecting section of a light guiding section of a display device. A diagram showing an example of the structure ... for explaining angles θ1, θ2, and θ3. A diagram for more specifically explaining angle θ2. A diagram showing an example of a usage situation when the tilt of the display panel is small. A diagram showing an example of a usage situation when the tilt of the display panel is large. A diagram for explaining the relationship between angles θ1, θ2, and θ3. A diagram for explaining the relationship between angle θ1 and the sunlight reception length ratio. A diagram for explaining the relationship between angle θ2 and the virtual image size reduction ratio. A diagram for explaining a usage situation when angles θ1 and θ3 are in a predetermined relationship.

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

[0010] First, an example of a system configuration will be described with reference to Fig. 1. Fig. 1 is a schematic diagram showing an example of the configuration of a vehicle 2 equipped with a display device or virtual image display device 1. With respect to the vehicle 2 and the driver, the horizontal direction X is the left-right direction, the lateral direction of the vehicle, or the width direction of the vehicle, the vertical direction Z is the up-down direction or longitudinal direction of the vehicle, and the horizontal direction Y, which is perpendicular to the lateral direction of the vehicle, is the front-rear direction of the vehicle or the direction of travel of the vehicle. The display device 1 may also be referred to as a virtual image display device. In the following description, the term "display device" will be used.

[0011] 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, periodically detect the values ​​of various parameters related to the driving situation, and acquire road and other information from a navigation device. The vehicle information 4 includes, for example, the vehicle 2's 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 (Global Positioning System) information, navigation information, vehicle-to-vehicle communication information, and road-to-vehicle communication information. The camera image information includes in-vehicle camera image information and outside-vehicle camera image information. The GPS information includes latitude and longitude as well as current time information. The vehicle information 4 also includes information input by the driver.

[0012] Based on such vehicle information 4, the display device 1 projects / emits image light onto a display area 5 of the windshield 3. As a result, the display device 1 superimposes a virtual image corresponding to the displayed image onto the scenery, allowing the driver (from the driver's viewpoint) of the vehicle 2 to view it. In this embodiment, projection of image light onto the display area 5 of the windshield 3 will be described, but the projection unit that projects the image light may be a projection member such as a combiner.

[0013] The display device 1 is connected to a controller 100 of the vehicle 2 via an information transmission path, and the display device 1 and the controller 100 can communicate with each other. 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 with each other via the information transmission path, for example, by a Controller Area Network (CAN). Note that the display device 1 and the controller 100 of the vehicle 2 may also communicate with each other via an in-vehicle Ethernet or the like via the information transmission path.

[0014] For example, when all information including video information is transmitted over a single information transmission path, the connection between the controller 100 (a source of video information, etc.) on the vehicle 2 side and the display device 1 (in other words, the connection form of the information transmission path) may be FPD-Link III, GMSL (Gigabit Multimedia Serial Link), or the like.

[0015] The controller 100 controls the vehicle 2 based on the input and output of data, and an in-vehicle system is configured by being connected to the display device 1. The in-vehicle system is a system in which the controller 100 can control the vehicle 2 using vehicle information 4.

[0016] Next, an example of a device used to acquire vehicle information will be described with reference to Fig. 2. Control of the display device will be described with reference to Figs. 3 and 4. Fig. 2 shows an example of a device used to acquire vehicle information. Figs. 3 and 4 are functional block diagrams showing an example of the configuration of the main control parts of the display device.

[0017] The control unit of the display device 1 can acquire vehicle information data based on a communication protocol corresponding to, for example, a CAN (Controller Area Network) interface, a LIN (Local Interconnect Network) interface, etc. The controller 100 of the vehicle 2 can also acquire data in a similar manner.

[0018] As shown in Fig. 2, the vehicle information 4 is acquired using devices such as cameras and various sensors connected to the controller 100 or the control device. Note that 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. Also, as an example, the controller 100 of the vehicle 2 may have a function of controlling the display device 1.

[0019] The vehicle speed sensor 901 detects the speed of the vehicle 2 and is used to generate speed information, which is the detection result. The shift position sensor 902 detects the current gear and is used to generate gear information, which is the detection result. The steering wheel angle sensor 903 detects the current steering wheel angle and is used to generate steering wheel angle information, which is the detection result. The headlight sensor 904 detects whether the headlights are on or off and is used to generate lamp illumination information, which is the detection result.

[0020] The illuminance sensor 905 and chromaticity sensor 906 detect external light from the vehicle 2 and are used to generate external light information that serves as the detection result. The distance measurement sensor 907 detects the distance between the vehicle 2 and an external object or the distance between two external objects and is used to generate distance information that serves as the detection result. The infrared sensor 908 detects the presence or absence of an object in the vicinity of the vehicle 2 and the distance thereto and is used to generate infrared information that serves as the detection result. The engine start sensor 909 detects whether the engine is on or off and is used to generate on / off information that serves as the detection result.

[0021] 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 that indicates the attitude and behavior of the vehicle 2 .

[0022] The temperature sensor 914 detects the temperature inside and outside the vehicle and is used to generate temperature information representing the detection results.

[0023] For example, if the display device 1 is housed in 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. Here, the temperature sensor 914 may be disposed inside the dashboard, as an example. However, the temperature sensor 914 may also be disposed in another location where the temperature may be similar to that inside the dashboard.

[0024] Furthermore, when the display device 1 is not housed in the dashboard, such as on the dashboard, the temperature sensor 914 may be used to detect the temperature in the vicinity of where the display device 1 is installed. If a temperature that may affect the operation of the display device 1 due to direct sunlight or the like is detected, the display device 1 may stop operating. Here, the temperature sensor 914 may be disposed on the dashboard, as an example. The temperature sensor 914 may also be disposed outside the vehicle, assuming that the temperature in the vicinity of the display device 1 and the temperature outside the vehicle are similar.

[0025] The road-to-vehicle communication wireless transceiver 915 generates road-to-vehicle communication information through road-to-vehicle communication between the vehicle 2 and roads, signs, traffic lights, etc. The vehicle-to-vehicle communication wireless transceiver 916 generates vehicle-to-vehicle communication information through vehicle-to-vehicle communication between the vehicle 2 and other surrounding vehicles. The mobile terminal-to-vehicle communication wired and wireless communication unit 917 is a device that acquires information through wired communication or wireless communication from devices (e.g., Wi-Fi devices) connected to an LTE (Long Term Evolution) network. The controller 100 or the control device can acquire information transmitted and received over the LTE network via the mobile terminal-to-vehicle communication wired and wireless communication unit 917.

[0026] 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, by analyzing the captured images, the driver's fatigue state, line of sight position, etc. can be ascertained.

[0027] On the other hand, the exterior camera 920 captures images of the surroundings, such as the area in front of and behind the vehicle 2. In this case, by analyzing the captured images, it becomes possible to determine the presence or absence of obstacles such as other vehicles or people in the vicinity, buildings, topography, road conditions such as rain, snow, ice, and unevenness, road signs, etc. The exterior camera 920 also includes, for example, a drive recorder that records images of the situation while driving.

[0028] 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 (Vehicle Information and Communication System, registered trademark) receiver 922 generates VICS information by receiving VICS signals. The GPS receiver 921 and the VICS receiver 922 may be provided as part of a navigation system.

[0029] The voice of the driver is input to the voice input device 918, which is used to generate voice information. By uttering a voice, the driver can input operation details via the voice input device 918. The vehicle operation switch 911 is used to generate information on the driver's operation of the steering switch and the like.

[0030] Furthermore, the video generation unit 910 generates video information based on the vehicle information 4 acquired by the controller 100 of the vehicle 2 .

[0031] 3 and 4 are block diagrams for controlling the entire display device 1 and each unit, and mainly control the display of a projected image (virtual image) on the display device 1.

[0032] 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, an image processing unit 1013, a communication processing unit 1014, a display driver 1021, and a light source driving unit 1022. In the example of FIG. 3 , the communication processing unit 1014 receives and transmits main vehicle information 4, but may also function as a control unit of the display device 1. The image processing unit 1013 receives image information or image data generated by the image generation unit 910 of the controller 100 of the vehicle 2. The image processing unit 1013 does not generate images, but processes images 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).

[0033] 4, similarly to the case of FIG. 3, the device includes a microcontroller (MCU) 1010, a non-volatile memory 1011, a volatile memory 1012, a communication processing unit 1014, an image processing unit 1015, a display driver 1021, and a light source driving unit 1022, all mounted on a wiring board. However, in the example of FIG. 4, the image processing unit 1015 has the function of the image generation unit 910, and generates image information using acquired information (e.g., vehicle information 4) instead of receiving image information. The image processing unit 1015 can also perform processes such as distortion correction and conversion on the generated image information.

[0034] 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 mounted within the MCU 1010 as appropriate. 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 structures shown in FIGS. 3 and 4 may be, for example, a control unit mounted within the housing of the display device 1, or a control unit mounted outside the housing.

[0035] 3, the MCU 1010 receives video information via, for example, FPD-Link III or GMSL via the communication processing unit 1014. The MCU 1010 may perform processing such as distortion correction and conversion on the received video information as a function of the video processing unit 1013. The video processing unit 1013 is mainly realized by the CPU of the MCU 1010 reading and executing a program stored in the non-volatile memory 1011 or the volatile memory 1012.

[0036] 4 , the MCU 1010 receives the vehicle information 4 via, for example, the CAN or in-vehicle Ethernet through the communication processing unit 1014. As a function of the video processing unit 1015, the MCU 1010 can generate video data to be sent to the video display unit 200 based on the vehicle information 4. The video processing unit 1015 is mainly realized by the CPU of the MCU 1010 reading and executing a program stored in the non-volatile memory 1011 or the volatile memory 1012.

[0037] That is, the video processing unit (1013, 1015) processes video data that determines the display content of the display video to be projected onto the display area 5 of Fig. 1 etc., based on the acquired information. The display driver 1021 drives each display element (pixel) included in the display panel 11 based on the video data. As a result, the video display unit 200 or the video display unit 200 creates and displays an image to be projected onto the display area 5 based on the video data.

[0038] 1, distortion correction corrects image distortion caused by the curvature of windshield 3 when an image from display device 1 is projected onto display area 5. Display driver 1021 then drives each display element (pixel) included in display panel 11 based on the corrected image data. As a result, image display section 200 or image display unit 200 creates and displays an image to be projected onto display area 5 based on the corrected image data.

[0039] Furthermore, the light source driving unit 1022 can adjust the light source, and adjusts the brightness of the image forming unit PGU1 or the light source 20 in the image forming unit PGU1. Based on the vehicle information 4 received via the communication processing unit 1014, the light source 20 is controlled using the light source driving unit 1022, which is a driver used to drive the light source.

[0040] 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 20 in the image forming unit PGU1 and suppresses the amount of light from the light source 20 that is incident on the display panel 11, thereby suppressing a rise in temperature of the display panel 11.

[0041] 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, and the like.

[0042] The volatile memory 1012 mainly stores acquired information and various data used in the processing of each unit in the MCU 1010. The communication processing unit 1014 is a device equipped with a communication interface, and communicates with the outside of the display device 1 based on a communication protocol such as CAN or LIN. The communication processing unit 1014 may be integrated with the vehicle information acquisition unit.

[0043] 3 and 4 may be implemented as a dedicated circuit such as a field programmable gate array (FPGA) as appropriate. In this embodiment, the control device is configured to have a nonvolatile memory 1011 and a volatile memory 1012, but the above processing may be performed by a single memory.

[0044] Next, the video display unit 200 will be described in detail. The video display unit 200 or video display unit 200 includes an image forming unit PGU1 that projects video light. The image forming unit PGU1 displays an image based on video data and projects video light of the displayed image. The image forming unit PGU1 includes a light source 20 and a display panel 11 such as a liquid crystal display (LCD) having video display elements.

[0045] The image forming unit PGU1 is a projector (projection type image display device) that uses light emitted from a light source 20 (in other words, light source light) to project image light of an image formed on the display panel 11. The light source 20 is typically configured to include an LED (Light Emitting Diode).

[0046] The display panel 11 creates an image based on the image data and displays it on the display screen of the display panel 11. In this embodiment, the image data is described as image data input from the image processing units (1013, 1015). The display panel 11 modulates the transmittance of light from the light source 20 for each pixel in accordance with the image data, thereby forming an image to be projected onto the display area 5 and projecting it as image light (in other words, projection light).

[0047] The display panel 11 is not limited to a liquid crystal panel, but may be a screen plate with a diffusion function. As a means for projecting an image onto a screen plate with a diffusion function, a means for projecting an image of a DMD (Digital Micromirror Device) or a liquid crystal panel in combination with a projection lens, or a means using a micro electro mechanical system may be used.

[0048] The light source 20 is configured using, for example, a semiconductor light source element, and generates predetermined light source light and supplies it to the display panel 11. The light source 20 functions as a backlight source for the display panel 11. A typical example of the semiconductor light source element is an LED (Light Emitting Diode) element. The light source 20 may be configured by arranging a plurality of light sources.

[0049] A backlight section is configured using the light source 20 etc. A specific configuration example of the backlight section will be described later.

[0050] The image light emitted from the display panel 11, in other words, the projection light, is directed toward the display area 5 of the windshield 3. Therefore, the user of the display device 1 can view the image light as a virtual image. This allows the driver to view the image light projected onto the display area 5 as a virtual image beyond the transparent windshield 3, superimposed on the scenery outside the vehicle (e.g., roads, buildings, people, etc.). The virtual image, which is the projected image, can be a variety of images, such as road signs, the current speed of the vehicle, and various types of information added to objects in the scenery. This allows for the realization of an augmented reality (AR) function that adds various types of information to and displays objects in the scenery.

[0051] However, there is a possibility that visibility may be reduced due to sunlight entering the display device 1. Next, a technique for suppressing the reduction in visibility due to sunlight will be specifically described.

[0052] 5 , an image of information, an alert, or the like to be displayed as a virtual image 10 is generated on a display panel 11 such as an LCD, and the image generated on the display panel 11 is projected as image light rays 13 using a light source in a backlight unit. The image light rays 13 are reflected by the windshield 3 and enter an eye box 14, allowing the driver to recognize the virtual image 10.

[0053] Here, as an example, the position (X, Y, Z) of the display panel 11 is roughly determined based on the angle of the windshield 3, the depression angle of the virtual image 10 relative to the position of the eye box 14, and the virtual image distance, which is the distance between the eye box 14 and the virtual image 10. In this case, the display panel 11 is disposed, for example, on or inside the dashboard of the vehicle 2. However, if external light such as sunlight is reflected by the display panel 11 and enters the eye box 14, the external light such as sunlight may become unnecessary stray light and deteriorate visibility. Here, for example, if a cover or the like is provided around the display device 1 to prevent sunlight from entering, the cover or the like may block the optical path of the image light 13, making it impossible to see the virtual image 10. Therefore, it is not easy to take complete measures against external light.

[0054] Therefore, by tilting the display panel 11 toward the driver as shown in FIG. 5, the following effects (1) to (3) can be obtained.

[0055] (1) By tilting the display panel 11 at an appropriate angle and taking measures to direct external light such as sunlight 15 away from the eye box 14, it is possible to prevent the external light such as sunlight 15 from being reflected by the display panel 11 and causing a deterioration in visibility. In other words, a measure against stray light due to specular reflection is realized.

[0056] (2) The energy from the sun 16 and the light from the backlight cause the display panel 11 to become hot, which can lead to component failures such as a decrease in brightness due to temperature characteristics and screen burn. Here, the greater the inclination of the display panel 11, the less solar energy is incident on the display panel 11, and a heat countermeasure for the display panel 11 can be realized.

[0057] (3) Since the display panel 11 is tilted, the length of the display device 1 in the longitudinal direction of the vehicle is shortened, which makes it easier to mount the display device 1, for example, on top of or inside a narrow dashboard. In other words, the degree of freedom in layout is improved.

[0058] Next, with reference to FIGS. 6 and 7 , an example configuration of the image forming unit will be described. The image forming unit or image display unit includes a light source unit 12a and a display panel 11. As shown in FIG. 6A , the light source unit 12a may also be referred to as a backlight unit. The light source unit 12a includes a light source 20, a reflecting mirror 21, a polarization conversion element 22, and a light guide unit 23a, and may also include a diffuser plate 24. The reflecting mirror 21 is configured to reflect light from the light source 20 and control it to be parallel light. The reflecting surface of the reflecting mirror 21 is a parabolic surface, and may have a shape asymmetric with respect to the optical axis of the light emitted from the light source 20. The reflecting mirror 21 may also be disposed eccentrically with respect to the light source 20. The reflecting mirror 21 may also be referred to as a reflecting unit or a reflector. The polarization conversion element 22 is composed of a polarizing beam splitter (PBS) and a retardation film (½λ), and separates incident light into S-polarized light and P-polarized light, and polarizes either the separated S-polarized light or P-polarized light using the retardation film (½λ), thereby outputting the randomly polarized light incident on the polarization conversion element 22 as linearly polarized light. In this embodiment, the polarization conversion element 22 aligns the polarization of the light emitted from the light source 20, thereby achieving high efficiency in image projection.

[0059] The light guide 23a adjusts the angle of incidence of light rays on the display panel 11. In this example, the light guide 23a is configured using a light reflector 60 having a prism shape (a jagged shape). The light guide 23a may be, for example, a prism sheet. In this example, light rays incident on the light reflector 60 of the light guide 23a 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, inclination, and surface roughness of the reflecting surface of the light reflector 60. Therefore, in the structure of FIG. 6A , the direction of light rays from the light source 20 is, for example, as shown in the same figure. In this structure, 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. The light guide 23a is, for example, a resin member having a prism shape, and the prism-shaped portion that serves as the reflective surface is coated with an aluminum reflective film or the like. As shown in Fig. 6A, the light reflecting portion 60 of the light guide portion 23a may be configured with multiple inclinations on one surface to adjust the reflected light with higher precision. Furthermore, as shown in Fig. 6B, the reflecting surface may be configured with multiple or multifaceted surfaces, or may be configured with a curved surface. The diffuser plate 24 uniformly disperses the incident light from the light guide portion 23. The diffuser plate 24 has the effect of improving the brightness uniformity within the virtual image plane.

[0060] FIG. 6B shows an enlarged view of the light reflecting portion 60 of the light guide 23a. The light reflecting portion 60 has a sawtooth pattern of alternating reflective surfaces and connecting surfaces. Light incident on the light guide 23a is reflected upward by each reflective surface and then passes through the diffuser 24 to be adjusted to a predetermined light distribution characteristic before entering the display panel 11. The reflective surface elevation angles α1a, α2a, α3a, α4a, etc. are arbitrarily set to obtain a predetermined light distribution characteristic. Meanwhile, the relative angles β1a, β2a, β3a, β4a, etc. between the reflective surfaces and the connecting surfaces are set to a constant angle regardless of location, preferably an angle of 90 degrees or greater (βna≧90°). When fabricating the light guide 23a by injection molding, setting the relative angle βna to 90 degrees or greater facilitates mold processing of the reflective surfaces and connecting surfaces.

[0061] By appropriately setting the lengths and ratios of the connecting surfaces Lc1a, Lc2a, Lc3a, etc. and the reflecting surfaces Lr1a, Lr2a, Lr3a, etc., it is possible to realize a light source unit that can change the illumination range of light reflected by the light-guiding unit 23a to the size (surface size) required for a device such as the display panel 11. Furthermore, by appropriately adjusting the ratio Lr / Lc, it is possible to partially strengthen or weaken the reflected light. For example, the ratio Lr / Lc is adjusted according to the intensity distribution of light incident on the light-reflecting unit 60. More specifically, by reducing the ratio Lr / Lc in areas of the light-reflecting unit 60 where the intensity of the incident light is high, i.e., by setting the reflecting surface elevation angle αna at a fine pitch, it is possible to precisely control the light reflection direction and uniformly adjust the brightness distribution of light incident on the display panel 11.

[0062] While a reflecting mirror 21 is used for parallel light control in Fig. 6A, a configuration as shown in Fig. 7 may also be used. That is, as shown in Fig. 7, the light source unit 12b includes a light source 20, a lens 25, a polarization conversion element 22, and a light guide unit 23b. The incident light emitted from the light source 20 and converted into parallel light by the lens 25 is polarized by the polarization conversion element 22 and enters the light guide unit 23b. The light reflected by the light guide unit 23b is emitted toward the display panel 11. The light source unit 12b includes a lens 25 (collimating lens) for parallel light control instead of the reflecting mirror 21. In addition, in this light source unit 12b, the light source 20 is disposed so as to emit light toward the lens 25. The lens 25 controls the light from the light source 20 to be parallel light.

[0063] Furthermore, while the light guide unit 23a in FIG. 6 is configured to bend light rays toward the display panel 11 using a prism-shaped light guide unit, the light guide unit 23a may have a configuration as shown in FIG. 7 . That is, as shown in FIG. 7 , the light guide unit 23b may be made of a transparent material such as resin or glass, and may include a light entrance unit 26, a light reflecting unit 27, and a light exit unit 28, with light distribution controlled based on the shapes of these three surfaces. In this case, the light from the light source 20 may be reflected by total reflection in the reflecting unit 27, or may be reflected by an aluminum reflective film or the like coated on the reflective surface. In the structure of FIG. 7 , the direction 30 of the backlight rays is, for example, as shown in the figure. In this structure, the optical axis of the light source 20 and the optical axis of the light incident on the display panel 11 are approximately perpendicular to each other.

[0064] 7 has the function of internally reflecting and refracting light taken in from incident portion 26 as parallel light from light source 20 via lens 25 and polarization conversion element 22, guiding the light in a desired direction and extracting it as planar light having a desired area. Light guide portion 23b includes light incident portion 26 of the light guide portion facing the exit surface of polarization conversion element 22, light reflecting portion 27 forming an inclined surface, and light exit portion 28 that emits light to display panel 11. In light incident portion 26 of light guide portion 23b, the main light ray is deflected by a predetermined angle in a direction that increases the angle of incidence with respect to light reflecting portion 27. In other words, light incident portion 26 is formed in a curved convex shape inclined toward light source 20. The light reflecting section 27 has a number of reflective surfaces and connecting surfaces alternately formed in a sawtooth pattern. Light incident on the light guiding section 23b is reflected by each reflective surface and directed upward. The light then travels through the light emitting section 28 and the diffuser 24, adjusted to a predetermined light distribution characteristic, before entering the display panel 11. The reflective surface elevation angles α1b, α2b, α3b, α4b... are set so that each reflective surface is equal to or greater than the critical angle with respect to the incident light. Meanwhile, the relative angles β1b, β2b, β3b, β4b... between the reflective surfaces and the connecting surfaces are set to a constant angle regardless of location, preferably 90 degrees or greater (βnb≧90°). When the light guiding section 23b is fabricated by injection molding, setting the relative angle βn to 90 degrees or greater facilitates mold processing of the reflective surfaces and the connecting surfaces. Since each reflecting surface is configured so that the angle with respect to the incident light is always equal to or greater than the critical angle, total reflection is possible without forming a reflective film such as a metal on the light reflecting portion 27, and a light source device can be realized at low cost that includes a light guide portion 27 that guides light in a desired direction and extracts it as planar light having a desired area. On the other hand, in a structure in which a reflective film is formed on the light reflecting portion 27, the angle of incidence on the reflective surface can be set as desired, increasing the degree of freedom in designing the light guide portion 23b.

[0065] By appropriately setting the lengths and ratios of the connecting surfaces Lcb1, Lcb2, Lcb3, etc. and the reflecting surfaces Lrb1, Lrb2, Lrb3, etc., the length of the light emitting portion 28 in the optical axis direction can be freely changed. This makes it possible to realize a light source unit in which the size (surface size) of the light emitting portion 28 relative to the light incident portion 26 can be adjusted to the size (surface size) required for a device such as the display panel 11. Furthermore, by appropriately adjusting the ratio Lr / Lc, it is possible to partially strengthen or weaken the reflected light. For example, the ratio Lr / Lc is adjusted according to the intensity distribution of light incident on the light reflecting portion 27. More specifically, by reducing the ratio Lr / Lc in areas of the light reflecting portion 27 where the intensity of the incident light is high, i.e., by setting the reflecting surface elevation angle αnb at a fine pitch, the light reflection direction can be precisely controlled and the brightness distribution of the light incident on the display panel 11 can be uniformly adjusted.

[0066] For example, the light source unit may have a structure in which light guide unit 23b is provided instead of light guide unit 23a in the structure of Fig. 6. Also, the light source unit may have a structure in which light guide unit 23a is provided instead of light guide unit 23b in the structure of Fig. 7.

[0067] 6 and 7, angle 40 (θ1) indicates the angle at which display panel 11 is tilted with respect to the horizontal plane when display device 1 is mounted in order to protect against sunlight, and the angle formed between display panel 11 or diffuser plate 24 and the exit surface of the light guide unit may be different from angle 40 (θ1). Therefore, when display device 1 is mounted, the exit portion of the light source does not need to be parallel to the horizontal plane.

[0068] Angle 41 (θ2) indicates the emission angle of the image light emitted from the display panel 11, and angle 43 (θ2) indicates the incidence angle of the image light (or backlight light) incident on the display panel 11. These angles (41, 43) are determined with respect to a perpendicular line 44 of the display panel 11, and angle 41 and angle 43 are equal. The relationship between angle 40 (θ1), angle 41 (θ2), angle 43 (θ2), etc. will be explained in detail later.

[0069] As shown in Fig. 8, the light source unit may have a structure including a prism-shaped optical component 31 through which light that has been converted to parallel light by a lens 25 passes. That is, a structure may be adopted in which light rays bent by the optical component 31 are incident on a light guide component of the light guide unit 23a or on a reflecting surface of the light reflector 27. Also, as shown in Fig. 9, the parallel light control unit including the light source 20 may be tilted to adjust (set) an angle 32 of the light source 20 to, for example, an optimal angle. Similarly, the reflecting mirror 21 may be tilted to change its orientation.

[0070] Next, the angles θ1, θ2, and θ3 will be described with reference to FIGS.

[0071] As shown in Figure 10, the light-emitting surface side of the display panel 11 faces the driver, and the angle between the display panel 11 and a horizontal plane in the horizontal or lateral direction of the vehicle is angle 40 (θ1). That is, angle 40 (θ1) is the inclination of the display panel 11 with respect to the horizontal plane. Angle 41 (θ2) is the emission angle of the image light with respect to a perpendicular line 44 of the display panel 11, and angle 43 (θ2) is the incident angle of the image light (or backlight light) with respect to the perpendicular line of the display panel 11. Angle 42 (θ3) determines the angle of the windshield 3 with respect to the horizontal plane.

[0072] 10 and 11, the angle of emission of image light ray 13 from display panel 11 is expressed as a positive numerical value. As shown in Fig. 11, angles 41 (θ2) and 43 (θ2) formed by the image light and the vertical direction (perpendicular line 44) of display panel 11 are equal to each other. That is, there is a relationship that emission angle 41 (θ2) = incident angle 43 (θ2).

[0073] For example, when designing to project a virtual image so that the FoV is 11 x 4 [deg], the virtual image distance is 1100 [mm], the depression angle is 5.5 [deg], and the eye box 14 is 150 x 70 [mm], the angles are set as shown in (1) to (3) below, as an example. (1) The tilt angle 40 (θ1) of the display panel 11 relative to the horizontal plane is 60 degrees, and the incident angle 43 (θ2) of the image light (or backlight light) on the display panel 11 is +26 degrees. (2) The tilt angle 40 (θ1) of the display panel 11 relative to the horizontal plane is 31 degrees, and the incident angle 43 (θ2) of the image light (or backlight light) on the display panel 11 is +2 degrees (almost vertical). (3) The tilt angle 40 (θ1) of the display panel 11 relative to the horizontal plane is 14.5 degrees, and the incident angle 43 (θ2) of the image light (or backlight light) on the display panel 11 is -19 degrees.

[0074] As shown in Figure 10, the tilt of the display panel 11 in the horizontal and vertical directions of the vehicle is the angle between the light incident surface of the display panel 11 and the horizontal plane. If it is desired to increase the tilt of the display panel 11, the backlight unit 12 is designed so that the angle of incidence of light from the backlight unit 12 (in other words, the angle of emission from the display panel 11) is in the + direction (the direction indicated by the symbol θ+ in Figure 11).

[0075] Next, an example of a usage situation of the display device 1 will be described with reference to Fig. 12 and Fig. 13. Fig. 12 shows an example of a usage situation when the tilt of the display panel is small. Fig. 13 shows an example of a usage situation when the tilt of the display panel is large.

[0076] 12, when the inclination of the display panel 11 is small, the length 51 of the display panel 11 along the vehicle longitudinal direction, in other words, the range of sunlight 15 incident on the display panel 11 or the length of sunlight reception, becomes large, and more sunlight enters the display panel 11. As a result, the display panel 11 absorbs sunlight 15 from the sun 16 and image light, and becomes hot, which is thought to cause, for example, a decrease in brightness due to temperature characteristics, a burn, or other malfunctions.

[0077] Furthermore, an increase in length 51 may cause physical interference 55 in an area 53 where meters, instruments, and the like are arranged, thereby limiting the location where display device 1 can be placed. Also, an increase in length 51 may cause interference inside dashboard 52, which also limits the location where display device 1 can be placed.

[0078] Therefore, it is preferable to increase the inclination of the display panel 11 and decrease the length 51 of the display panel 11 along the vehicle longitudinal direction. In the example of Fig. 12, the installation angle (θ1) of the display panel 11 is set to 31 degrees, and the area of ​​the display panel 11 is set to 204 mm × 65 mm. The length 51 of the display panel 11 along the vehicle longitudinal direction is 65 mm × cos(31°), or approximately 56 mm.

[0079] 13 , when the inclination of the display panel 11 is large, the length 54 of the display panel 11 along the vehicle longitudinal direction, in other words, the range of sunlight 15 incident on the display panel 11 or the length of sunlight reception, becomes small. This reduces the amount of sunlight energy received by the display panel 11 from the sun 16, and reduces the effect of sunlight 15 on the display panel 11. In other words, deterioration of the display panel 11 due to sunlight incidence can be suppressed, and the reliability of the display device 1 can be improved.

[0080] Furthermore, the reduction in length 54 makes it easier to arrange the display device 1 so as not to cause physical interference with the area 53 where meters, instruments, etc. are arranged. Also, it makes it easier to arrange the display device 1 so as not to cause interference inside the dashboard 52. From this perspective, it is possible to improve the degree of freedom in layout.

[0081] For example, by reducing the length 54, the display device 1 can be easily mounted on a narrow dashboard 52 or inside the dashboard 52. Here, the display device 1 may be provided so that the upper surface of the dashboard 52, in which an opening is formed, and the surface of the display panel 11 are flush with each other. Furthermore, when the display panel 11 is disposed inside the dashboard 52, a light-transmitting cover may be provided over the opening of the dashboard 52.

[0082] 13, the installation angle (θ1) of the display panel 11 is set to 60 degrees, and the area of ​​the display panel 11 is set to 202 mm × 73 mm. The length 54 of the display panel 11 along the vehicle longitudinal direction is 73 mm × cos(60°), which is approximately 42 mm.

[0083] The display panel 11 of the display device 1 is preferably arranged so as not to be directly visible to the driver 50. Therefore, as shown in Figures 12 and 13, it is preferable that meters, instruments, etc. are arranged in the line of sight 56 ​​of the driver 50 toward the upper end of the display panel 11, and the display device 1 is provided so that the display panel 11 is hidden from the line of sight 56 ​​of the driver 50. Alternatively, the HUD device 1 may be stored in a dashboard 52. In this manner, when the HUD device 1 is arranged so that it is not directly viewed by the driver 50, it is possible to prevent stray light caused by external light entering the HUD device 1 being reflected by the display panel 11 and directly entering the eyes of the driver 50.

[0084] Next, the relationship between the angles (θ1, θ2, θ3) will be described with reference to Figures 14 to 16. The meanings of angles θ1, θ2, and θ3 are as explained above using Figures 10 and 11. The six line graphs shown in Figure 14, from the bottom up, represent data for θ3 = 25°, θ3 = 30°, θ3 = 35°, θ3 = 40°, θ3 = 45°, and θ3 = 50°.

[0085] As shown in Fig. 14 , as a sunlight protection measure by tilting the display panel 11, the tilt angle θ1 of the display panel 11 with respect to the horizontal plane is preferably 30° or more. Specifically, with reference to Fig. 15 , by setting the angle θ1 to 30°, the sunlight receiving length (i.e., the vertical length of the display panel 11 × cos(θ1)) is shortened by approximately 10% compared to when the display panel 11 is not tilted (θ1 = 0°), and the sunlight energy entering the display panel 11 can be reduced by approximately 10%. Furthermore, when the angle θ1 is less than 30°, the sunlight receiving length decreases gradually, but when the angle θ1 is 30° or more, the decrease in the sunlight receiving length becomes linear, thereby achieving good sunlight protection.

[0086] Tilting the display panel 11 reduces the virtual image size (FoV) (more specifically, the vertical size of the virtual image is reduced). Here, from the viewpoint of suppressing a reduction in the FoV, it is preferable that the incident angle or emission angle θ2 of the image light (or backlight light) relative to the display panel 11 is 40° or less. Specifically, with reference to FIG. 16 , when the angle θ2 is 40° or less, the reduction in the virtual image size (FoV) is gradual. However, when the angle θ2 is 40° or more, the reduction in the virtual image size becomes linear, and the reduction in the virtual image size becomes greater as the angle θ2 increases. Therefore, as shown in FIG. 14 , it is preferable that the angle θ2 is 40° or less.

[0087] Note that when the relationship between the angle θ1 of the display panel 11 with respect to the horizontal plane and the windshield angle θ3 with respect to the horizontal plane shown in FIG. 14 is θ1≧90°−θ3, i.e., when the perpendicular to the display panel 11 intersects with the roof of the vehicle 2, sunlight is blocked by the roof of the vehicle 2, and sunlight does not enter the display panel 11 from the front. FIG. 17 shows the relationship between the angle θ1 of the display panel 11 with respect to the horizontal plane and the angle θ3 of the windshield with respect to the horizontal plane is θ1=90°−θ3, in which the perpendicular to the display panel 11 and the windshield 3 are parallel or approximately parallel, and the roof of the vehicle 2 blocks sunlight that would otherwise be incident on the front of the display panel 11. Furthermore, when θ1>90°−θ3, the perpendicular to the display panel 11 tilts toward the rear of the vehicle and intersects with the roof of the vehicle 2. Therefore, when the sun 16 is located directly in front of the display panel 11, sunlight is blocked by the roof of the vehicle 2.

[0088] On the other hand, if the incident angle or outgoing angle θ2 of the image light (or backlight light) with respect to the display panel 11 becomes too large, the brightness or contrast of the image may decrease due to a decrease in transmittance, which is a characteristic of the display panel 11. Therefore, as shown in Fig. 14A, it is preferable to set the angle θ2 to 50° or less.

[0089] Furthermore, as shown in FIG. 14 , the angle θ1 of the display panel 11 relative to the horizontal plane and the angle of incidence or emission θ2 of the image light (or backlight light) relative to the display panel 11 differ depending on the tilt angle θ3 of the windshield relative to the horizontal plane; the smaller the angle θ3, the easier it tends to be to suppress a reduction in the FoV; in other words, it was found that the smaller the angle θ2 is and the smaller the angle θ3 is, the easier it is to set the angle θ1 large while suppressing a reduction in the FoV.

[0090] From the above viewpoint, the relationship between the tilt angle θ1 of the display panel 11 with respect to the horizontal plane, the incident angle θ2 of the image light (or backlight light) with respect to the display panel 11 or the exit angle θ3 of the image light, and the angle θ3 of the windshield with respect to the horizontal plane may be, for example, as follows: (1) When the windshield tilt (θ3): is 25 to 30 degrees, θ1: 30 degrees to 80 degrees, θ2: -5 degrees to 40 degrees. (2) When the windshield tilt (θ3): is 30 to 35 degrees, θ1: 30 degrees to 70 degrees, θ2: 5 degrees to 50 degrees. (3) When the windshield tilt (θ3): is 35 to 40 degrees, θ1: 30 degrees to 60 degrees, θ2: 15 degrees to 50 degrees. (4) When the windshield tilt (θ3): is 40 to 45 degrees, θ1: 30 degrees to 50 degrees, θ2: 25 degrees to 50 degrees. (5) Windshield tilt (θ3): When 45 to 50 degrees, θ1: 30 to 40 degrees, θ2: 35 to 50 degrees

[0091] 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.

[0092] For example, the portion of the windshield 3 onto which the image light is projected may be configured such that a black film is attached to the interior of the vehicle, or such that a black ceramic is applied to the interior of the vehicle, so that the background of the projected image is black. A black background for the image increases the contrast between the image brightness and the background brightness, improving the driver's visibility of the image. Even in this case, tilting the display panel 11 toward the driver can shorten the vehicle's longitudinal length, thereby improving layout flexibility.

[0093] A vehicle 2 (vehicle) on which the display device 1 is mounted is typically an automobile.

[0094] In the technology according to this embodiment, by tilting the display panel toward the driver with respect to the windshield, it is possible to provide an information display device (head-up display device) that can provide sunlight protection, display a good virtual image, and reduce the driver's eye movement, thereby contributing to supporting safe driving and preventing traffic accidents. This contributes to the achievement of "Good health and well-being for all," one of the Sustainable Development Goals (SDGs) advocated by the United Nations.

[0095] 1 Display device (virtual image display device) 11 Display panel

Claims

1. A display device comprising: a display panel capable of emitting image light onto a vehicle windshield; and a light source that emits light to the display panel, the display panel being oriented toward a driver of the vehicle, and the display panel being tilted relative to a horizontal plane.

2. A display device according to claim 1, characterized in that the angle between said display panel and a horizontal plane is 30° or more.

3. A display device as claimed in claim 1, characterized in that, when the emission angle of the image light from the display panel when the image light is emitted from the display panel towards the front of the vehicle from a line perpendicular to the display panel is expressed as a positive numerical value, the emission angle of the image light from the display panel is not less than -5° and not more than 50°.

4. A display device as claimed in claim 1, characterized in that, when the emission angle of the image light from the display panel when the image light is emitted from the display panel towards the front of the vehicle from a line perpendicular to the display panel is expressed as a positive numerical value, the emission angle of the image light from the display panel is not less than -5° and not more than 40°.

5. A display device according to claim 3, characterized in that the angle of the windshield with respect to the horizontal plane is between 25° and 50°.

6. A display device according to claim 4, characterized in that the angle of the windshield with respect to the horizontal plane is between 25° and 50°.

7. A display device according to claim 1, characterized in that the display panel is arranged in the vehicle so as to be hidden from the driver's field of vision.

8. A display device according to claim 1, characterized in that the display panel is disposed so that a perpendicular line of the display panel intersects with a roof of the vehicle.

9. A vehicle equipped with a display device according to any one of claims 1 to 8.

Images