Display device, vehicle, and display system

Abstract

The purpose of the present invention is to provide technology capable of improving the visibility of content projected in front of a driver. The present invention contributes to Sustainable Development Goal "3 - Good Health and Well-being for all people". This display system, which is mounted in a vehicle, comprises a light source, a display panel on which light from the light source is incident, and a light transmission / shielding switching unit on which image light projected by the display panel is incident. The light transmission / shielding switching unit switches between a light-shielding state and a semi-transmitting state in part or all of region in which the image light is incident, depending on the image being projected.

Description

Display device, vehicle, display system

[0001] The present invention relates to a display device, a vehicle, and a display system.

[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 Laid-Open No. 2022-168351

[0004] There is a need to provide a technology that can improve the visibility of content projected in front of the driver.

[0005] According to the present invention, there is provided, as an example, the following display device. This display device is a device to be mounted on a vehicle and includes a light source, a display panel onto which light from the light source is incident, and a transmission / shield switching unit onto which video light projected by the display panel is incident. The transmission / shield switching unit is capable of switching between a light-blocking state and a semi-transmitting state in part or all of an area onto which the video light is incident. Also, according to the present invention, there is provided, as an example, the following display device. This display device is a device to be mounted on a vehicle and includes a light source, a display panel onto which light from the light source is incident, and a transmission / shield switching unit onto which video light projected by the display panel is incident. The transmission / shield switching unit is disposed in front of the driver, contains a photochromic dye, and is capable of switching between a light-blocking state and a semi-transmitting state depending on the amount of ultraviolet or visible light. Also, according to the present invention, there is provided, as an example, the following display device. This display device is a display device to be mounted on a vehicle and includes a light source, a display panel onto which light from the light source is incident, and a light-blocking unit onto which video light projected by the display panel is incident. The light-shielding portion has a shape that is longer in the left-right direction of the vehicle than the area where the video light is incident, and has a generally trapezoidal shape whose left-right length decreases from the bottom to the top of the vehicle. Furthermore, the size of content rendered by the display panel, font size, or the dimension of the same content in the left-right direction of the vehicle decreases from the bottom to the top of the vehicle. Furthermore, according to the present invention, as an example, the following display system is provided. The display system is a system to be mounted on a vehicle and includes a light source, a display panel onto which light from the light source is incident, and a transmission / shading switching unit onto which video light projected by the display panel is incident. The transmission / shading switching unit switches between a light-shielding state and a semi-transmission state in part or all of the area onto which the video light is incident, depending on the projected video.

[0006] According to the present invention, it is possible to improve the visibility of content and realize a more suitable display technology. Note that problems, configurations, and effects other than those described above will become clear from the following description of the preferred embodiment of the invention.

[0007] 6A is a diagram illustrating an example of a vehicle equipped with a display device. FIG. 6B is a diagram illustrating an example of a configuration related to image display. FIG. 6C is a diagram illustrating an example of a display when the transmission / blocking switching unit blocks light. FIG. 6D is a diagram illustrating an example of a display when the transmission / blocking switching unit semi-transmits light. FIG. 6E is a diagram illustrating an example of a display when the transmission / blocking switching unit blocks only light related to the display area. FIG. 6F is a diagram illustrating an example of a structure of the transmission / blocking switching unit. FIG. 6A is a diagram illustrating an example of a display when the transmission / blocking switching unit blocks only light related to the display area. FIG. 6C is a diagram illustrating an example of a structure of the transmission / blocking switching unit. FIG. 6D is a diagram illustrating an example of a display when the transmission / blocking switching unit blocks only light related to the display area. FIG. 6E is a diagram illustrating an example of a structure of the transmission / blocking switching unit. FIG. 6F is a diagram illustrating an example of a display when the transmission / blocking switching unit blocks only light related to the display area. 14 is a diagram showing an example of the configuration of a vehicle. FIG. 15 is a diagram showing an example of the configuration of a display device. FIG. 16 is a diagram showing an example of the configuration of a display device. FIG. 17 is a flowchart showing an example of control of a transmission / blocking switching unit. FIG. 18 is a diagram for explaining an example of determination item A in FIG. 14. FIG. 19 is a diagram showing an example of the configuration of an image forming unit. FIG. 20 is a diagram showing an example of a light reflecting unit of a reflective optical element. FIG. 21 is a diagram showing an example of the configuration of an image forming unit. FIG. 22 is a diagram showing an example of the structure of an image forming unit. FIG. 23 is a diagram showing an example of the structure of an image forming unit. FIG. 24 is a flowchart showing an example of control of a transmission / blocking switching unit.

[0008] 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.

[0009] For the purpose of explanation, when describing processing by a program, the program, functions, processing units, etc. may be described as the main components, but the main hardware components are the processor, or a controller, device, computer, system, etc. that is configured with the processor, etc. The computer executes processing according to the program read into memory using resources such as memory and communication interfaces as appropriate through the processor. This realizes predetermined functions, processing units, etc. The processor is configured, for example, with semiconductor devices such as a CPU / MPU or GPU. Processing is not limited to software program processing, and can also be implemented using dedicated circuits. Dedicated circuits such as FPGAs, ASICs, and CPLDs can be used.

[0010] First, an example of a vehicle equipped with a display device will be described with reference to Fig. 1. Fig. 1 is a schematic diagram showing an example of the configuration of a vehicle equipped with a display device or a virtual image display device. With respect to the vehicle 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 y is the up-down direction or longitudinal direction of the vehicle, and the horizontal direction z, 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 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 the display area 5 of the windshield 3. In this way, the display device 1 allows the driver of the vehicle 2 to view the displayed image. 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 configuration related to image display will be described with reference to FIG. 2 . The display device 1 is provided, for example, on or within the dashboard 70. The display device 1 projects image light toward the display area 5 of the windshield 3 described above. A transmission / shading switching unit is provided in the display area 5 of the windshield 3. This transmission / shading switching unit is used to control light transmission and shading, and is indicated by hatching in the figure. Specific configuration examples of the transmission / shading switching unit will be described in detail later. When the transmission / shading switching unit blocks light, the driver 9 of the vehicle 2 can view a display image that is not superimposed on the scenery. When the transmission / shading switching unit semi-transmits light, the driver 9 of the vehicle 2 can view a virtual image 8 corresponding to the display image superimposed on the scenery. The transmission / shading switching unit may be provided in the display device 1 or the vehicle 2.

[0017] Next, with reference to FIGS. 3A and 3B , an example of a display when the transmission / shield switching unit blocks light is described. In this example, the entire transmission / shield switching unit 924a is in a light-shielding state, thereby lowering the background luminance of the image, and ensuring visibility even at low image luminance. Therefore, for example, when the image background is black, navy blue, or indigo, low image luminance reduces power consumption when the image is displayed. Alternatively, low image luminance reduces the energy (heat energy and light energy, in this example) generated when the image is displayed. This reduces product degradation and extends the product life. Furthermore, external light (sunlight) is blocked by the transmission / shield switching unit 924a, preventing external light from entering the display panel of the display device. As a result, temperature rise of the display panel is suppressed, and degradation of the display panel is suppressed.

[0018] 3A and 3B, the transmission / shading switching unit 924a is provided, for example, across the entire lower portion of the windshield 3 so as not to obstruct the driver's field of vision. That is, the transmission / shading switching unit 924a is provided across the left and right sides of the lower portion of the windshield 3. However, it is sufficient that the transmission / shading switching unit is provided in the portion used for video display. That is, the transmission / shading switching unit may be provided in the display area 5 or according to customer needs.

[0019] Next, with reference to Figures 4A and 4B, an example of a display in which the transmission / shield switching unit semi-transmits light will be described. In this example, the entire transmission / shield switching unit 924a is in a semi-transmitting state, allowing the driver of the vehicle to see ahead through the transmission / shield switching unit 924a, thereby improving driving safety. Note that the transmission / shield switching unit 924a can be provided in the same manner as described above in Figures 3A and 3B.

[0020] Next, with reference to Figures 5A and 5B, an example of a display in which the transmission / shield switching unit blocks only light related to the display area will be described. In this example, only the entire area of ​​the transmission / shield switching unit 924a related to the display area 5 is in a light-shielding state, and the remaining area is in a semi-transparent state. This makes it possible to suppress the incidence of external light (sunlight) on the display panel, thereby suppressing temperature increases and optical degradation of the display panel. Furthermore, the semi-transparent portion provides forward visibility, improving driving safety.

[0021] The transmission / shading switching unit 924a can adjust the area in the display area 5 that is in a light-blocking state depending on the content of the video to be displayed. For example, the transmission / shading switching unit 924a can block out the background part of the video (e.g., the outline of the content) in addition to the displayed part of the content, thereby achieving good visibility even when the video brightness is low. On the other hand, the transmission / shading switching unit 924a may block out only the part that overlaps with the content displayed in the display area 5, and make the other part semi-transparent.

[0022] 6A and 6B, an example of the shape of the transmission / shade switching unit will be described. For example, the transmission / shade switching unit 924b can be provided at the bottom of the windshield 3 so that its left-right length decreases from the bottom to the top of the windshield 3. As shown in the figures, the transmission / shade switching unit 924b blocks light from the portion overlapping the content and the surrounding portion, which is a substantially trapezoidal or trapezoidal portion whose left-right length decreases from the bottom to the top (in this example, the entire display area 5). Furthermore, the display device 1 projects image light that displays content with a shape that creates a sense of perspective, thereby realizing a display that provides the driver of the vehicle with an easy-to-perceive sense of perspective.

[0023] More specifically, when the transmission / shield switching portion 924b has a shape that is longer in the left-right or width direction of the vehicle than the area where the image light is incident and has an approximately trapezoidal or trapezoidal shape that becomes shorter in the left-right direction from the bottom to the top of the vehicle, the size of the content drawn by the display panel, the font size, or the dimension of the same content in the left-right direction of the vehicle becomes smaller from the bottom to the top of the vehicle, thereby making it easier for the driver to perceive a sense of perspective in the displayed image. Note that such a display that makes it easier to perceive a sense of perspective is not limited to when the transmission / shield switching portion 924b is provided in the display area 5, and may also be when, for example, black ceramic printing is provided in the display area 5 as a light-shielding portion. If the shading portion provided in the display area 5 has a shape that is longer in the left-right direction of the vehicle than the area where the image light enters, and is an approximately trapezoidal or trapezoidal shape whose left-right length decreases as it moves from the bottom to the top of the vehicle, the size of the content drawn by the display panel, the font size, or the left-right dimensions of the vehicle within the same content can be made smaller as it moves from the bottom to the top of the vehicle, making it easier for the driver to perceive a sense of perspective in the displayed image.

[0024] In the figure, the transmission / shading switching unit 924b has a generally trapezoidal or trapezoidal shape whose length in the left-right direction decreases from the bottom to the top of the vehicle. However, the same effect can be achieved by projecting video light that displays content with a perspective shape by blocking only the generally trapezoidal portion (i.e., the entire display area 5) as described above and semi-transmitting the remaining portion. Therefore, the shape of the transmission / shading switching unit may be changed as appropriate. For example, the transmission / shading switching unit may be provided at the bottom of the windshield 3 and may be longer in the left-right direction of the vehicle than the display area 5 onto which the display panel 11 projects the video light. The transmission / shading switching unit may be in the light-blocking state over the entire display area 5 and semi-transmitting the remaining portion.

[0025] 7 to 10, examples of the configuration of the transmission / shield switching unit will be described in more detail. The transmission / shield switching unit (924a, 924b) contains liquid crystal and a dye or pigment, and is configured to align the dye or pigment in a predetermined direction by the liquid crystal.

[0026] Here, it is desirable that the transmission / light-shielding switching units (924a, 924b) be normally black. Normally black is a light-shielding state when no voltage is applied. In this case, when the vehicle is not in use, it is possible to suppress the incidence of external light SL (e.g., sunlight) on the display panel, thereby suppressing product deterioration. Specifically, it is possible to suppress the incidence of external light SL when the vehicle engine is off (when the ignition switch is off), when the electrically driven vehicle is not in use (when the power switch for enabling the electric vehicle to run is off), etc.

[0027] The transmission / shield switching units (924a, 924b) may be sheet-shaped and, for example, may be provided on the surface of the windshield 3 on the driver's seat side (inside of the windshield 3). The transmission / shield switching units (924a, 924b) may also be included in an intermediate film of the windshield 3. A half mirror, a reflective polarizing film, or the like may be provided on the incident surface (the surface on which light enters) of the transmission / shield switching units (924a, 924b). The half mirror, the reflective polarizing film, or the like may be provided on the incident surface on which the image light IL enters, or on the incident surface on which the ambient light SL enters. The image light IL entering the transmission / shield switching units (924a, 924b) including a half mirror, a reflective film, or the like is reflected with high efficiency by the half mirror, the reflective film, or the like, thereby achieving power savings during image display. This suppresses product degradation due to energy (in this example, thermal energy and light energy) generated during image display, thereby extending the product life. On the other hand, external light SL incident on the transmission / shield switching units (924a, 924b) is blocked by a half mirror, a reflective polarizing film, etc., and therefore does not enter the display panel of the display device. As a result, the temperature rise of the display panel is suppressed, and deterioration of the display panel is suppressed.

[0028] An example of the light-blocking state of the transmission / blocking switching unit will be described with reference to Figures 7A and 7B. In this example, the display device projects image light IL toward the transmission / blocking switching units (924a, 924b), and the image light IL is reflected by the transmission / blocking switching units (924a, 924b) and directed toward the driver. The driver can see a virtual image (i.e., an image display without a superimposed landscape) corresponding to the displayed image on the transmission / blocking switching units (924a, 924b) in the light-blocking state. Furthermore, external light SL incident on the transmission / blocking switching units (924a, 924b) is absorbed (or reflected) by at least the transmission / blocking switching units (924a, 924b) in the light-blocking state, and does not enter the interior of the vehicle through the transmission / blocking switching units (924a, 924b). Here, as shown in Figure 7B, in areas where the transmission / shield switching units (924a, 924b) are in a light-shielding state, the dye or pigment contained in the transmission / shield switching units (924a, 924b) is randomly oriented in the xy plane or xyz space. In other words, in the light-shielding area, the dye or pigment is not oriented in a specific direction. In the figure, the dye or pigment is indicated by the symbol D.

[0029] An example of the semi-transmitting state of the transmission / shielding switching unit will be described with reference to FIGS. 8A and 8B . As shown in the figures, in the semi-transmitting areas of the transmission / shielding switching units (924a, 924b), the dye or pigment in the transmission / shielding switching units (924a, 924b) is oriented in the x-axis direction, which corresponds to the vehicle width direction. In the figures, the dye or pigment is indicated by the symbol D. Then, the polarized component of the image light IL (in this example, the P-polarized component) enters the transmission / shielding switching units (924a, 924b), and a portion of the image light IL is Fresnel-reflected at the incident surface and directed toward the driver. Furthermore, the polarized component of the ambient light SL (in this example, the P-polarized component) passes through the transmission / shielding switching units (924a, 924b). As a result, the display device projects P-polarized image light IL, allowing the driver to view a virtual image corresponding to the displayed image superimposed on the scenery.

[0030] Note that, because the transmission / blocking switching units (924a, 924b) are provided in a partial area of ​​the windshield 3, it is conceivable that external light SL will enter the vehicle interior from the windshield 3 without passing through the transmission / blocking switching units (924a, 924b). Even if the driver wears polarized sunglasses (in this example, sunglasses that block S-polarized light) as a countermeasure against the external light SL directly entering the vehicle interior, the polarized component of the image light IL (in this example, the P-polarized component) and the polarized component of the external light SL (in this example, the P-polarized component) will pass through the polarized sunglasses, allowing the driver to view a virtual image corresponding to the displayed image superimposed on the scenery.

[0031] As shown in the figure, even when the display device projects S-polarized image light IL onto the transmission / shield switching section (924a, 924b) in which the dye or pigment is oriented in the x-axis direction, the image light IL is Fresnel reflected at the incident surface of the transmission / shield switching section (924a, 924b), and the driver can see a virtual image corresponding to the displayed image.

[0032] Furthermore, when the image light IL is S-polarized, the component that is not Fresnel reflected at the incident surface of the transmission / shield switching unit (924a, 924b), i.e., the image light IL that enters the transmission / shield switching unit (924a, 924b), is absorbed by the dye or pigment oriented in the x-axis direction. This suppresses double images that occur when the image light IL is Fresnel reflected at the back surface (surface facing the exterior of the vehicle) of the windshield 3.

[0033] Note that the same figure has been used to explain the transmission-blocking switching units (924a, 924b) in which the dye or pigment D is oriented in the x-axis direction. However, in the transmission-blocking switching units (924a, 924b), the dye or pigment D may be oriented in the y-axis direction. In this case as well, the image light IL is Fresnel-reflected at the incident surface of the transmission-blocking switching units (924a, 924b) regardless of the polarization direction of the image light, and the driver can view a virtual image corresponding to the displayed image.

[0034] Furthermore, when the image light IL is P-polarized, as described above, the image light IL that enters the inside of the transmission / shield switching section (924a, 924b) is absorbed by the dye or pigment D, thereby suppressing the occurrence of double images.

[0035] An example of the semi-transmitting state of the transmission / shielding switching unit will be described with reference to FIGS. 9A and 9B . In this example, the orientation direction of the transmission / shielding switching unit (924a, 924b) is different from that described above. That is, in the area where the transmission / shielding switching unit (924a, 924b) is in the semi-transmitting state, the dye or pigment in the transmission / shielding switching unit (924a, 924b) is oriented along the xy plane so as to form an angle of approximately 45° with respect to the x-axis direction (corresponding to the vehicle width direction) and the y-axis direction (corresponding to the vehicle's vertical direction). Note that in the same figure, the dye or pigment is indicated by the symbol D. In this example, image light IL is projected with a polarization direction parallel to the orientation direction of the dye or pigment D. The image light IL enters the transmission / shielding switching unit (924a, 924b), and a portion of the image light IL is Fresnel-reflected at the incident surface and directed toward the driver. The driver can then view a virtual image corresponding to the displayed image superimposed on the scenery. Furthermore, the polarized component of the external light SL that is perpendicular to the orientation direction of the dye or pigment D is transmitted through the light transmission / blocking switching sections (924a, 924b).

[0036] Because the image light IL and the external light SL transmitted through the transmission / blocking switching units (924a, 924b) are polarized components tilted at approximately 45° with respect to the x-axis, the driver can view the scenery and a virtual image corresponding to the displayed image even when wearing polarized sunglasses, for example, as a countermeasure against external light directly entering the vehicle interior. By wearing polarized sunglasses, the brightness of the external light SL transmitted through the windshield 3 (including the external light SL transmitted through the transmission / blocking switching units (924a, 924b)) and the brightness of the image light IL are each approximately halved, so the driver does not feel uncomfortable wearing the sunglasses. In other words, the driver perceives the same darkness for the scenery seen through the windshield 3 (including the scenery seen through the transmission / blocking switching units (924a, 924b)) and the virtual image 8 when wearing the polarized sunglasses. Therefore, the contrast within the driver's field of vision remains constant before and after wearing the polarized sunglasses, so the driver does not feel uncomfortable wearing the polarized sunglasses.

[0037] Furthermore, the component of the image light IL that is not Fresnel reflected at the incident surface of the transmission / shield switching portion (924a, 924b), i.e., the image light IL that enters the transmission / shield switching portion (924a, 924b), is absorbed by the oriented dye or pigment, thereby suppressing double images that occur when the image light IL is Fresnel reflected at the rear surface (surface facing the exterior of the vehicle) of the windshield 3.

[0038] An example of the semi-transmittance state of the transmission / shield switching unit will be described with reference to FIGS. 10A and 10B . In this example, the orientation direction of the transmission / shield switching unit (924a, 924b) is different from that described above. That is, in the area where the transmission / shield switching unit (924a, 924b) is in the semi-transmittance state, the dye or pigment in the transmission / shield switching unit (924a, 924b) is oriented along the z-axis direction, which is perpendicular to the xy plane and corresponds to the longitudinal direction of the vehicle. In the figure, the dye or pigment is indicated by the symbol D. In this example, the occupancy rate of the dye or pigment D in the xy plane decreases, thereby increasing the transmittance, thereby making it easier to see the scenery seen through the transmission / shield switching unit (924a, 924b). Note that the external light SL remains randomly polarized and transmits through the transmission / shield switching unit (924a, 924b) with a reduced amount of light.

[0039] The image light IL is projected onto the transmission / shield switching units (924a, 924b), and a portion of the image light IL is Fresnel-reflected on the incident surface of the transmission / shield switching units (924a, 924b) and directed toward the driver. The driver can then view a virtual image corresponding to the displayed image superimposed on the scenery. The polarization direction of the image light IL is arbitrary, and random polarization is also possible, but projecting S-polarized image light IL achieves high reflectivity at the interface of the transmission / shield switching units (924a, 924b), making the image brighter. However, a portion of the image light IL passes through the transmission / shield switching units (924a, 924b) and is reflected by the back surface (outside the vehicle) of the windshield 3, creating a double image. Therefore, it is desirable to take measures to prevent double images, such as using a wedge glass.

[0040] As explained above, even when wearing polarized sunglasses as a countermeasure against external light directly entering the vehicle, the driver can view a virtual image corresponding to the displayed image, except when the image light IL is S-polarized. Here, when the image light IL is randomly polarized, circularly polarized, or linearly polarized at approximately 45° with respect to the x-axis and y-axis, wearing the polarized sunglasses reduces the brightness of the external light SL (including the external light SL transmitted through the transmission-blocking switching units (924a, 924b)) that passes through the windshield 3 and the brightness of the image light IL by approximately half, so the driver does not feel uncomfortable wearing the sunglasses. In other words, when wearing the polarized sunglasses, the driver perceives the same darkness for the scenery seen through the windshield 3 (including the scenery seen through the transmission-blocking switching units (924a, 924b)) and the virtual image 8. Therefore, the contrast in the driver's field of vision remains constant before and after wearing the polarized sunglasses, and the driver does not feel uncomfortable wearing the polarized sunglasses. By arranging a transmission / shield switching section or a shading section, double images that occur when image light is Fresnel reflected on the back surface of the windshield (the surface facing outside the vehicle) are suppressed, improving the visibility of the content and enabling the realization of a more suitable display device.

[0041] Next, an example of the configuration of a vehicle will be described with reference to Fig. 11. Note that the vehicle may be equipped with a transmission / shield switching unit, and in the configuration example of Fig. 11, the vehicle is equipped with a transmission / shield switching unit (924a or 924b), and a controller or control device of the vehicle controls the transmission / shield switching unit (924a, 924b).

[0042] As shown in Fig. 11 , the vehicle includes a controller 100 or a control device. The controller 100 or the control device (sometimes referred to as controller 100) acquires vehicle information using devices such as a connected camera and various sensors. Note that the various devices in Fig. 11 can be deleted, or other types of devices can be added or replaced with other types of devices as appropriate. Furthermore, as an example, the controller 100 of the vehicle 2 may have a function related to control of the display device 1.

[0043] 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.

[0044] 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.

[0045] 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 .

[0046] The temperature sensor 914 detects the temperature inside and outside the vehicle and is used to generate temperature information representing the detection results.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] Furthermore, the video generation unit 910 generates video information based on the vehicle information 4 acquired by the controller 100 of the vehicle 2 .

[0053] The raindrop sensor 923 detects raindrops adhering to the windshield 3 of the vehicle 2, and the controller 100 acquires information about the raindrops as a detection result. As described above, the transmission / shading switching units (924a, 924b) are components used to control light transmission and shading, and as an example, the controller 100 can control the operation of the transmission / shading switching units (924a, 924b) based on a control process described below.

[0054] Next, a configuration example of the display device will be described with reference to Fig. 12 and Fig. 13. The display device 1 can be provided with a transmission / shield switching unit, and in the configuration examples of Fig. 12 and Fig. 13, the display device is provided with a transmission / shield switching unit (924a or 924b), and a processor of the display device (in these examples, MCU 1010) controls the transmission / shield switching unit (924a, 924b).

[0055] 12 , 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. 12 , 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).

[0056] 13 , similarly to the case of FIG. 12 , 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. 13 , 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.

[0057] 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. 12 and 13 may be, for example, a control unit mounted within the housing of the display device 1, or a control unit mounted outside the housing.

[0058] 12, 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.

[0059] 13 , 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 transmitted 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.

[0060] 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 image forming unit 10 or the image forming unit 10 creates and displays an image to be projected onto the display area 5 based on the video data.

[0061] 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 forming section 10 or image forming unit 10 creates and displays an image to be projected onto display area 5 based on the corrected image data.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] Each unit of the control device in Figures 12 and 13 may be implemented as a dedicated circuit such as an FPGA (Field Programmable Gate Array) as appropriate. In this embodiment, the device is configured to have a non-volatile memory 1011 and a volatile memory 1012, but the above processing may also be performed by a single memory. In Figure 13, the image processing unit of the display device creates an image based on information acquired from the vehicle, while in Figure 12, the image is acquired from the vehicle.

[0067] Next, the image forming unit will be described in detail. The image forming unit PGU1 displays an image based on image data and projects image 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 image display elements.

[0068] The image forming unit PGU1 uses light emitted from the 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).

[0069] 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).

[0070] 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 to form a real image onto the 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.

[0071] 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.

[0072] A backlight section is configured using the light source 20 etc. A specific configuration example of the backlight section will be described later.

[0073] 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, a user of the display device 1 can, for example, view the image light as a virtual image. This allows the driver to view, for example, 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.). Projected images can include various types of images, such as road signs, the vehicle's current speed, and various types of information added to objects in the scenery. This allows, for example, an augmented reality (AR) function to be realized, which adds various types of information to objects in the scenery and displays them.

[0074] Next, an example of control of the transmission / shading switching unit will be described with reference to FIGS. 14 and 15. The main processing unit is a processor that controls the transmission / shading switching unit (924a, 924b). The processor may be the controller 100 of the vehicle, or the MCU or control unit of the display device. Furthermore, the processor that controls the transmission / shading switching unit may be further provided in the display device or the vehicle.

[0075] 14, when control of the transmission / shield switching unit (924a, 924b) starts, the processor makes a judgment for judgment item A (S01). Then, depending on the judgment result, the processor controls in the first mode or the second mode (S02, S03), and ends the processing.

[0076] In the first mode, a portion or the entire display area is shaded. When a portion of the display area is shaded, the remaining portion is semi-shaded (i.e., semi-transparent), thereby ensuring both driving visibility and display visibility. In addition, in the first mode, information can be aggregated and displayed in a shaded portion of the display area. For example, when the shaded area is adjusted from the entire display area to a portion of the display area depending on surrounding conditions and vehicle information during driving, such as driving speed, navigation information, whether driving on an ordinary road or a highway, the displayed information is aggregated in the shaded portion. When the displayed information is aggregated in the shaded portion, the size of the displayed content may be reduced, or low-priority information may be deleted to display only more important displayed content. In the first mode, for example, the transparent / shaded switching unit (924a, 924b) may shade a portion of the display area by controlling the shaded area according to the shape, contour, and color of the displayed content. Also, for example, the transmission / shield switching sections (924a, 924b) may be configured to block light only at the incident position of the image light and its surroundings.

[0077] The selection of whether to shade a portion of the display area or the entire area may be controlled automatically. In this case, the processor may select whether to shade a portion of the display area or the entire area depending on, for example, the content to be projected. For example, when projecting content related to video or content such as navigation information, the entire display area may be shaded. When projecting content of a still image such as sign information, only a portion of the display area (for example, only the periphery of the content) may be shaded. On the other hand, the user may set the shaded portion of the display area themselves.

[0078] In the second mode, the entire display area is in a semi-shading state (i.e., semi-transparent state), allowing the driver to view the content superimposed on the scenery outside the vehicle.

[0079] An example of the determination item A related to S01 will be specifically described with reference to Fig. 15. In the determination example shown in Fig. 15, if determination condition 1 is met, the first mode is selected (S02), and if determination condition 2 is met, the second mode is selected (S03).

[0080] For example, in S01, the processor determines whether the user has selected the first mode or the second mode (Determination Example 1). That is, when the processor receives an instruction to block part or all of the display area, it performs control based on the first mode. When the processor receives an instruction to block all or part of the display area, it performs control based on the second mode. For example, when the processor receives an instruction to block all or part of the display area, it performs control based on the second mode. For example, when a driver wants to drive while checking the surrounding conditions, the driver can, for example, set the display area to the semi-transparent state (i.e., the second mode) to make it easier to obtain the surrounding conditions. Alternatively, the driver can set only part of the display area to the light-blocking state (i.e., the first mode) and aggregate information there to make it easier to obtain the surrounding conditions. In this case, the information may be displayed small, and visibility can be improved by displaying it against a black background. Furthermore, when a driver wants to drive while viewing navigation information or speed information, the driver, for example, sets the display area to the light-blocking state. Here, for example, the driver sets the entire display area to the light-blocking state.

[0081] For example, in S01, the processor determines whether the remaining battery charge of the vehicle is greater than or less than a threshold (Determination Example 2). That is, the processor determines whether the remaining battery charge of the vehicle is less than or equal to the threshold. If the remaining battery charge is low, power can be saved by reducing the image brightness by entering a light-blocking state.

[0082] For example, in S01, the processor determines whether the brightness outside the vehicle is greater than or less than a predetermined threshold (Determination Example 3). That is, the processor determines whether the brightness outside the vehicle is greater than or less than the threshold. The processor can use, for example, information acquired using the illuminance sensor 905. When it is bright outside the vehicle, the light-blocking state can be used to ensure the visibility of the image. Furthermore, by using the light-blocking state, it is possible to suppress the temperature rise due to the incidence of sunlight, thereby extending the product life. When it is dark outside the vehicle (such as at night), the semi-transparent state can be used to ensure the driver's forward visibility.

[0083] For example, in S01, the processor determines whether the vehicle's traveling speed is greater than or less than a threshold value (Determination Example 4). That is, the processor determines whether the vehicle's traveling speed is greater than or less than the threshold value. The processor may use, for example, information acquired using the vehicle speed sensor 901. When traveling at low speeds, visibility of the surrounding environment is important, so the processor makes the entire display area semi-transparent. For example, when traveling at low speeds in an urban area, the processor makes the entire display area semi-transparent, prioritizing ensuring driving visibility. On the other hand, when traveling (for example, when traveling on an ordinary road or a highway), the processor blocks out part or all of the display area.

[0084] For example, in step S01, the processor determines whether the vehicle's wipers are operating (Determination Example 5). In rainy weather, raindrops scatter light (e.g., external light or light from the headlights of oncoming vehicles), reducing the visibility of the image. Therefore, the light is blocked to improve the visibility of the image.

[0085] For example, in S01, the processor determines whether raindrops have been detected (Determination Example 6). The processor can use information acquired using, for example, the raindrop sensor 923. As in Determination Example 5, raindrops scatter light and reduce the visibility of the image, so a shading state is implemented to improve the visibility of the image.

[0086] For example, in step S01, the processor determines whether the vehicle ignition switch or the vehicle power supply is OFF (Determination Example 7). When the vehicle is not in use (for example, when the vehicle ignition is OFF or when the power switch for enabling the electric vehicle to run is OFF), the display device is placed in a light-blocking state to prevent deterioration of the display device due to external light (sunlight).

[0087] For example, in step S01, the processor determines whether an object (such as a pedestrian or an obstacle) is within a specified range around the vehicle (Determination Example 8). The processor may use information acquired using a distance sensor 907 (such as a sonar sensor or millimeter-wave radar). Alternatively, an infrared sensor 908 may be used. When an object is detected around the vehicle, the processor switches to a semi-transparent state to ensure visibility. On the other hand, when no object is detected around the vehicle, the processor switches to a light-blocking state.

[0088] Next, a specific example of the structure of the display device (specifically, the image forming unit 10) will be described with reference to FIGS.

[0089] FIG. 16A is a diagram showing an example of the configuration of an image forming unit. The display device has an image forming unit 10, which includes a display panel 11 having an image display element and a light source device 12 that emits light to the display panel 11. The display device uses light emitted from the light source device 12 (i.e., light source light) to project image light of an image formed on the display panel 11 onto a projection member. The display device may also be referred to as a projection display device. The display panel 11 forms an image to be projected onto the projection member based on image data and emits the image light (i.e., projection light). The display panel 11 may also be a liquid crystal panel LCD (Liquid Crystal Display) or the like. In this embodiment, the projection member or projection unit that projects the image light is the display area 5 of the windshield 3, but is not limited to the display area 5 of the windshield 3.

[0090] On the other hand, 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 to form a real image onto the 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.

[0091] The light source device 12 includes a light source 20, a reflecting mirror 21 (optical component), and a reflecting optical element 23a. The light source device 12 may also include a polarization conversion element 22 and a diffuser plate 25. The light source 20 is typically configured to include an LED (Light Emitting Diode) and may be referred to as a backlight unit. The light source 20 is configured with one or more LED light sources, and the multiple LED light sources may be arranged in a single row or in two or more rows, as long as they are arranged according to the design.

[0092] The reflecting mirror 21 is a component used to reflect light from the light source 20 and adjust it to approximately parallel light or parallel light. The reflecting surface of the reflecting mirror 21 is a parabolic surface, and may have a shape that is 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 portion or a reflector. In this embodiment, the description will be given using the reflecting mirror 21, but the optical component may also be a collimating lens.

[0093] 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.

[0094] The reflective optical element 23a may also be referred to as a light guide or a light guide. The reflective optical element 23a is configured to adjust the angle of incidence of light rays on the display panel 11, and may be, for example, a prism sheet. In this embodiment, the reflective optical element 23a has a light reflecting portion 24 having a prism shape (a jagged shape). Light rays incident on the light reflecting portion 24 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 reflective surface of the light reflecting portion 24. Furthermore, the reflective optical element 23a may be, for example, a resin member having a prism shape, and the prism-shaped portion that forms the reflective surface is coated with a reflective film or the like. Therefore, in the structure of FIG. 16A , 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.

[0095] 16B shows an enlarged view of the light reflecting portion 24 of the reflective optical element 23a. The light reflecting portion 24 has a sawtooth pattern with numerous reflective surfaces and connecting surfaces alternately arranged. Light incident on the reflective optical element 23a is reflected by each reflective surface and directed upward. The light then passes through the diffuser 25 and is 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 the reflective optical element 23a is manufactured by injection molding, setting the relative angle βna to 90 degrees or greater facilitates mold processing of the reflective surfaces and connecting surfaces.

[0096] 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 reflecting optical element 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 24. More specifically, by reducing the ratio Lr / Lc in areas of the light reflecting unit 24 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.

[0097] Fig. 17 shows a modified example of the display device shown in Fig. 16A. According to the reflective optical element 23b of Fig. 17, as shown in Fig. 16B, the ratio Lrb / Lcb of the length Lrb of the inclined surface projected onto a plane perpendicular to the emission direction of the multiple reflective surfaces of the light reflecting unit 232 to the length Lcb of the inclined surface projected onto a plane perpendicular to the emission direction of the reflective surface and the connecting surface connecting the reflective surface is variable depending on the location. Therefore, by appropriately setting the lengths and ratios of the connecting surfaces Lcb1, Lcb2, Lcb3, etc. and the reflective surfaces Lrb1, Lrb2, Lrb3, etc., the length of the light emitting unit 233 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 unit 233 relative to the light incident unit 231 can be changed to the size (surface size) required for a device such as the display panel 11.

[0098] Similarly, 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 232. More specifically, by reducing the ratio Lr / Lc in areas of the light reflecting portion 232 where the intensity of incident light is strong, that is, by setting the reflection surface elevation angle αnb at fine intervals, it is possible to precisely control the light reflection direction and uniformly adjust the luminance distribution of light incident on the display panel 11.

[0099] As shown in FIG. 18 , the image forming unit 10 may have an edge-type backlight structure, for example. A plurality of light sources 20 are arranged in a line in the depth direction of the drawing, facing the side of a light guide 23. The light guide 23 (a reflective optical element) is disposed on the rear side of the display panel 11, and a plurality of reflective dots 27 are provided on the light guide 23, emitting light toward the display panel 11. The reflective dots 27 diffusely reflect the guided light, thereby achieving uniform illuminance. The reflective dots 27 are formed on the light guide 23 by printing with white ink, forming a concave-convex shape, forming a groove pattern, or the like. Note that, in order to achieve uniform illuminance at positions closer to and farther from the light source 20, the reflective dots 27 may be formed so that their density increases with increasing distance from the light source 20. A reflective sheet 28 is provided facing the display panel 11, and the light guide 23 is disposed between the display panel 11 and the reflective sheet 28. In this case, light that is not diffused and reflected by the reflective dots 27 and that is emitted from the light guide 23 in the opposite direction to the display panel 11 is reflected by the reflective sheet 28 and enters the display panel 11 via the light guide 23. Also, in this example, a diffuser 25 is provided between the display panel 11 and the light guide 23, but the diffuser 25 may be omitted. Also, the diffuser 25 may be disposed after the display panel 11. Also, in this example, a reflective sheet 28 is provided to allow light to enter the light guide 23, but the reflective sheet 28 may be omitted.

[0100] As shown in FIG. 19 , the image forming unit 10 may have a direct-type backlight structure, for example. A plurality of light sources 20 are arranged below the display panel 11. The plurality of light sources 20 may be configured as an LED array, for example, using micro LEDs or mini LEDs. In this example, the plurality of light sources 20 are mounted on a substrate, and a reflective sheet 28 is provided on the surface of the substrate facing the display panel 11. A diffuser 25 is disposed between the display panel 11 and the reflective sheet 28. The diffuser 25 also has a plurality of reflective dots 27 formed on it, facing the light sources 20. This configuration allows light directly above the light sources 20, which tends to produce high-brightness spots, to be reflected by the reflective dots 27 and then by the reflective sheet 28 on the substrate. This makes it possible to uniformly adjust the brightness distribution of light incident on the display panel 11. The reflective dots 27 are formed on the diffuser 25 by printing white ink, forming a concave-convex shape, forming a groove pattern, or the like. The reflective sheet 28, the diffuser 25, and the reflective dots 27 may be omitted. Furthermore, a plurality of diffusion plates 25 on which no reflective dots 27 are formed may be used.

[0101] As shown in FIG. 20 , the image forming unit 10 may have a fly's eye integrator structure, for example. Between the display panel 11 and the light source 20, a lens array 31, a fly's eye lens 32, and a focus lens 33 are arranged in the order of light propagation direction. The lens array 31 converts light (LED light) emitted by the multiple light sources 20 (LEDs) into substantially parallel light. The fly's eye lens 32 forms an image of the light-emitting element, thereby improving the uniformity of the illumination surface. A configuration combining two fly's eye lenses may also be used. That is, a configuration may be used in which a first fly's eye lens splits a light beam, and each light beam is guided to the illumination area by a second decentered fly's eye lens. The focus lens 33 focuses light from the light source 20 onto the illumination surface.

[0102] From the above description, as an example, a display device including a light source 20, a display panel 11, and a transmission / shield switching unit (924a, 924b) is provided. That is, this display device is a device mounted on a vehicle 2. Light from the light source 20 is incident on the display panel 11. Image light projected by the display panel 11 is incident on the transmission / shield switching unit (924a, 924b). The transmission / shield switching unit (924a, 924b) is disposed in front of the driver and is capable of switching between a light-shielding state and a semi-transmitting state in part or all of an area where the image light is incident (an area corresponding to the display area 5). Furthermore, for example, this display device may include a processor (e.g., a vehicle controller 100 or an MCU of the display device) that controls switching between the light-shielding state and the semi-transmitting state of the transmission / shield switching unit (924a, 924b). Then, using this processor, for example, the processing described using FIGS. 14 and 15 may be performed. Furthermore, the processing described later (processing in FIG. 21) may be performed using this processor.

[0103] 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.

[0104] A transmission / blocking switching unit containing a photochromic dye may be used to switch between a light-blocking state and a semi-transmitting state. In this case, the dye changes color or fades depending on the amount of ultraviolet or visible light, causing a natural change in transmittance. When the outside of the vehicle is bright, the transmission / blocking switching unit is in a light-blocking state, and when the outside of the vehicle is dark (at night, in a tunnel, etc.), it is in a semi-transmitting state. In other words, the transmission / blocking switching unit naturally changes transmittance depending on the brightness outside the vehicle. Therefore, switching between the light-blocking state and the semi-transmitting state is possible without control by a processor. By providing a transmission / blocking switching unit or a light-blocking unit, double images caused by Fresnel reflection of image light on the back surface of the windshield (the surface facing the exterior of the vehicle) can be suppressed, improving the visibility of the content and realizing a more suitable display device.

[0105] In the determinations shown in FIGS. 14 and 15 , the processor may, for example, determine whether the vehicle 2 is in autonomous driving (or cruise control). During autonomous driving or cruise control, the entire display area may be shaded, giving priority to vehicle information (such as the driving situation) over driving visibility, allowing the information to be displayed in a larger size. It is also possible to display video content on a larger screen. To display information in a larger size, for example, the transparent / shaded switching unit may be provided across the entire lower portion of the windshield, as shown in FIG. 3A . That is, the transparent / shaded switching unit may be provided across the left and right sides of the lower portion of the windshield 3.

[0106] The orientation of the dye or pigment can be controlled by any suitable method. For example, a configuration for applying an electric field in a predetermined direction may be provided. This configuration may be controlled by a processor (e.g., the vehicle controller 100 or the MCU of the display device).

[0107] Whether the transmission / shading switching unit of the display area 5 in Figure 1 is in the light-blocking state or the semi-transmitting state is determined based on the transmittance of the transmission / shading switching unit, and if the transmittance is 10% or less, it is determined to be in the light-blocking state. If the transmittance of the transmission / shading switching unit is 10% or less, the background brightness of the projected image is sufficiently dark compared to the brightness of the image projected onto the display area 5, allowing the driver to clearly view the virtual image 8. Furthermore, in such a case, it is possible to suppress the incidence of external light on the display panel, thereby suppressing temperature rise and deterioration of the display panel.

[0108] In the first mode, a portion or the entire display area 5 is in a light-shielding state, and in the second mode, the entire display area 5 is in a semi-light-shielding state. When switching from the first mode to the second mode, the transmittance of the transparent / blackout switching unit increases, i.e., the background brightness of the projected image becomes brighter, thereby increasing the brightness of the projected image and ensuring the visibility of the virtual image 8. When switching from the second mode to the first mode, the brightness of the projected image is reduced and the projected image is switched to a color tone that is easy to see against a black background. More specifically, in the second mode, the transparent / blackout switching unit is in a semi-transparent state, so black cannot be used in the image display in principle, whereas in the first mode, the transparent / blackout switching unit is in a light-shielding state, i.e., the background of the projected image is black, so black can be used in the image display. In other words, when switching from the second mode to the first mode, the brightness and color tone of the projected image are adjusted to display the virtual image 8 with high visibility. On the other hand, at night, even when the transmission / shield switching unit is in the semi-transmission state (second mode), the background brightness of the projected image is dark, so when switching from the second mode to the first mode, it is not necessary to reduce the brightness of the projected image. For example, in the case of an LED light source, the brightness of the projected image is adjusted by adjusting the duty ratio in PWM (Pulse Width Modulation) control. Increasing the duty ratio increases the brightness of the projected image, and decreasing the duty ratio decreases the brightness of the projected image.

[0109] The transmission / shield switching units (924a, 924b) may be electrically connected to the vehicle 2, or may be electrically connected to the display device 1. When the transmission / shield switching units (924a, 924b) are electrically connected to the vehicle 2, the transmission / shield switching units (924a, 924b) are controlled on the vehicle 2 side. When the transmission / shield switching units (924a, 924b) are electrically connected to the display device 1, the transmission / shield switching units (924a, 924b) may be controlled by a control unit of the display device 1, or may be controlled by a controller of the vehicle 2 via the communication processing unit 1014 of the display device 1.

[0110] 21 is a flowchart showing an example of control of the transmission / shading switching unit for each image. As shown in FIG. 21, when control of the transmission / shading switching unit (924a, 924b) starts, in step S001, a mode corresponding to the image is determined. Depending on the determination result, the first mode or the second mode is selected (S002, S003), and the process ends.

[0111] When displaying an image containing text or characters, the background of the display area is shaded because small characters must be seen. Alternatively, when determining whether an image contains text or characters in step S001, the first mode, in which characters are easy to distinguish, is selected, and the process proceeds to step S002. When determining whether an image does not contain text or characters, the process proceeds to step S003 (second mode).

[0112] Furthermore, when the vehicle is stopped, the transmission / shield switching units (924a, 924b) are set to a light-shielding state to display an image with higher visibility. "Stopped" here refers to the state until the parking shift and brake are released. When the parking shift and brake are released, in other words, when the vehicle 2 starts moving, it is desirable to switch the transmission / shield switching units (924a, 924b) from the light-shielding state to the semi-transparent state to ensure the driver's visibility so that the surroundings of the vehicle are clearly visible.

[0113] From the above description, as an example, a display system including a light source 20, a display panel 11, and a transmission / shield switching unit (924a, 924b) is provided. That is, this display system is a system mounted on a vehicle 2. Light from the light source 20 is incident on the display panel 11. Image light projected by the display panel 11 is incident on the transmission / shield switching unit (924a, 924b). The transmission / shield switching unit (924a, 924b) is disposed in front of the driver and is capable of switching between a light-shielding state and a semi-transmitting state in part or all of an area where the image light is incident (an area corresponding to the display area 5). Furthermore, for example, this display system may include a processor (e.g., the vehicle controller 100 or the MCU of the display device) that controls switching between the light-shielding state and the semi-transmitting state of the transmission / shield switching unit (924a, 924b). Then, using this processor, for example, the processing described using FIGS. 14-15 and 21 may be performed.

[0114] In the technology according to the embodiment of the present invention, by disposing a light-transmitting / light-shielding switching unit that switches between a light-shielding state and a semi-transmitting state in a part or all of the area where the image light is incident, it is possible to improve the visibility of the content, realize a more suitable display device, and provide a display device that contributes to supporting safe driving and thereby makes it possible to prevent traffic accidents. This contributes to "Good health and well-being for all" of the Sustainable Development Goals (SDGs) advocated by the United Nations.

[0115] REFERENCE SIGNS LIST 1 display device 10 image forming section 11 display panel 12 light source device 20 light source 21 reflecting mirror (optical component) 22 polarization conversion element 23 light guide 23a reflecting optical element 23b reflecting optical element 24 light reflecting section 25 diffusion plate 27 reflective dot 28 reflective sheet 31 lens array 32 fly's eye lens 33 focus lens 923a transmission / shield switching section 923b transmission / shield switching section

Claims

1. A display device mounted on a vehicle, comprising: a light source; a display panel into which light from the light source is incident; and a light-transmitting / shielding switching section into which image light projected by the display panel is incident, wherein the light-transmitting / shielding switching section is capable of switching between a light-shielding state and a semi-transmitting state in part or all of an area into which the image light is incident.

2. A display device according to claim 1, wherein the light transmission / light blocking switching section contains a dye or coloring matter, and in the portion that is in the light blocking state, the dye or coloring matter is not oriented in a specific direction.

3. A display device according to claim 1, wherein the light transmission / shielding switching section contains a dye or pigment, and in the portion which is in the semi-transparent state, the dye or pigment is oriented in a predetermined direction.

4. A display device as claimed in claim 3, characterized in that the light-transmitting / light-shielding switching section contains a dye or pigment, and in the portion which becomes semi-transmitting, the dye or pigment is oriented so as to form an angle of approximately 45° with respect to the width direction and vertical direction of the vehicle within a plane defined by the width direction and vertical direction of the vehicle.

5. A display device according to claim 3, characterized in that the light-transmitting / light-shielding switching section contains a dye or pigment, and in the portion which is in the semi-transmitting state, the dye or pigment is oriented in the longitudinal direction of the vehicle, the width direction of the vehicle, or the up-down direction of the vehicle.

6. A display device as claimed in claim 1, characterized in that the area in the light-shielding state of the light-shielding switching section has a shape that is longer in the left-right direction of the vehicle than the area into which the image light is incident, and has a roughly trapezoidal shape whose left-right length decreases as it moves from the bottom to the top of the vehicle, and the size of the content or font size drawn by the display panel, or the left-right dimension of the vehicle within the same content, decreases as it moves from the bottom to the top of the vehicle.

7. A display device as claimed in claim 1, further comprising a processor in the display device or the vehicle that controls switching between the light-shielding state and the semi-transparent state of the light-transmitting / light-shielding switching section, wherein the processor switches all or part of the area to the light-shielding state when the remaining battery charge of the vehicle is less than a threshold value.

8. A display device as described in claim 1, further comprising a processor in the display device or the vehicle that controls switching between the light-shielding state and the semi-transparent state of the light-transmitting / light-shielding switching unit, wherein the processor switches part or all of the area to a light-shielding state when the brightness outside the vehicle is greater than a threshold value, and switches the entire area to a semi-transparent state when the brightness outside the vehicle is not greater than the threshold value.

9. A display device as claimed in claim 1, further comprising a processor in the display device or the vehicle that controls switching between the light-shielding state and the semi-transparent state of the light-transmitting / light-shielding switching unit, wherein the processor switches part or all of the area to a light-shielding state when the vehicle's travelling speed is greater than a threshold value, and switches the entire area to a semi-transparent state when the vehicle's travelling speed is not greater than the threshold value.

10. A display device as claimed in claim 1, further comprising a processor in the display device or the vehicle for controlling switching between the light-shielding state and the semi-transparent state of the light-transmitting / light-shielding switching section, wherein the processor switches part or all of the area to the light-shielding state when the windshield wipers of the vehicle are operating or raindrops are detected.

11. A display device as claimed in claim 1, further comprising a processor in the display device or the vehicle that controls switching between the light-shielding state and the semi-transparent state of the light-transmitting / light-shielding switching section, wherein the processor switches all or part of the area to a light-shielding state when the ignition switch or power supply of the vehicle is OFF.

12. A display device as described in claim 1, further comprising a processor in the display device or the vehicle that controls switching between the light-shielding state and the semi-transparent state of the light-transmitting / light-shielding switching unit, wherein the processor switches the entire area to the semi-transparent state when an object is present within a specified range around the vehicle.

13. A display device as claimed in claim 1, further comprising a processor in the display device or the vehicle that controls switching between the light-shielding state and the semi-transparent state of the light-transmitting / light-shielding switching section, wherein the processor switches the entire area to the light-shielding state when the vehicle is in autonomous driving or cruise control.

14. A display device mounted on a vehicle, comprising: a light source; a display panel into which light from the light source is incident; and a light-transmitting / shading switching unit into which image light projected by the display panel is incident, wherein the light-transmitting / shading switching unit is positioned in front of a driver, contains a photochromic dye, and is capable of switching between a light-blocking state and a semi-transmitting state depending on the amount of ultraviolet light or visible light.

15. A display device mounted on a vehicle, comprising: a light source; a display panel onto which light from the light source is incident; and a shading portion onto which image light projected by the display panel is incident, wherein the shading portion has a shape that is longer in the left-right direction of the vehicle than an area onto which the image light is incident, and has a roughly trapezoidal shape whose left-right length decreases as it moves from the bottom to the top of the vehicle, and wherein the size of content or font size drawn by the display panel, or the left-right dimension of the vehicle within the same content, decreases as it moves from the bottom to the top of the vehicle.

16. A vehicle equipped with a display device according to any one of claims 1, 14, and 15.

17. A display system to be mounted on a vehicle, comprising: a light source; a display panel into which light from the light source is incident; and a light-transmitting / light-shielding switching unit into which image light projected by the display panel is incident, wherein the light-transmitting / light-shielding switching unit switches between a light-shielding state and a semi-transmitting state in part or all of an area into which the image light is incident, depending on the image to be projected.

18. A display system according to claim 17, wherein when the image is an image including text or characters, the transparent / shade switching section is set to the shading state.

19. A display system according to claim 17, wherein the light-transmitting / light-blocking switching unit is in a light-blocking state when the vehicle is stopped.

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