Patent Application
20190329716
The present disclosure relates to a display device.
There has been known a head-up display (hereinafter, also abbreviated as HUD) directly reflecting information on a field of view of a human. The HUD is used in various fields such as automobile fields and airplane fields. In the case of being used in a vehicle such as automobile, the HUD displays various kinds of information on the conditions and traveling routes of a vehicle using images of numerals, characters, and graphics such as arrows, for example. Some of vehicle HUDs present virtual images formed in front of a windshield to a driver. For example, PTL 1 discloses a vehicle HUD apparatus that displays information such as driving information as a virtual image at a long distance via a windshield.
The present disclosure provides a display device that displays an image clearly.
A display device according to an aspect of the present disclosure is a display device that displays a virtual image by projecting an image onto a display medium and includes a light source unit, a screen, a self-emitting display unit, a scan unit, the screen, and a drive unit. The light source unit emits light. The screen is movably disposed on an optical path from the light source unit to the display medium. The self-emitting display unit is disposed adjacent to the optical path. The scan unit scans the screen with the light emitted from the light source unit. The drive unit moves the screen along the optical path. The screen is disposed to project an image imaged on the screen by scanning of the scan unit onto the display medium, and the self-emitting display unit is disposed to project an image generated by the self-emitting display unit onto the display medium.
It should be noted that the comprehensive or specific aspects above may be implemented by a system, a method, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM, or may be implemented by any combination of a system, a method, an integrated circuit, a computer program, and a (non-transitory) recording medium.
According to the display device of the present disclosure, it is possible to display an image clearly.
The inventors of the present invention have achieved the following findings in relation to the technology described in the section of “BACKGROUND ART”. The vehicle HUD device described in PTL 1 forms information as a virtual image to be superimposed on the foreground in the forward field of view on the opposite side of the windshield as seen from a driver. The vehicle HUD device moves a screen scanned with scanning light for forming an image in an optical-axis direction, thereby to change a forming position of the virtual image. The forming position of the virtual image is located in a depth direction of the virtual image as seen from the driver, which is also called display distance of the virtual image. For example, the vehicle HUD device described in PTL 1 performs control to change the display distance of the virtual image according to a running speed of the vehicle to reduce movement of point of view of the driver during driving. Specifically, the display distance of the virtual image is made longer when the running speed of the vehicle is fast than when the running speed of the vehicle is slow.
The vehicle HUD device described in PTL 1 includes a plurality of screens for displaying a virtual image via the windshield. The plurality of screens is aligned and independently movable. The positions of the plurality of screens as seen in the optical-axis direction are different from one another so that the plurality of screens displays a plurality of virtual images different in display distance at the same time. The screens can move along the optical axis to change the display distances of the virtual images over time. Accordingly, the vehicle HUD device displays the virtual images of objects around the vehicle, for example, intersections where the vehicle is to turn, other vehicles, and obstacles, while changing the display distances along with the travel of the vehicle.
The display information requested by the HUD includes information generated according to the travel of the vehicle and information constantly displayed during the running of the vehicle. For example, the information generated according to the travel of the vehicle is temporarily displayed information such as the traveling direction of the vehicle, the distance to right or left turn, and a warning about an obstacle, the information being desirably superimposed on the foreground in the forward field of view of the driver. For example, the information constantly displayed during the running of the vehicle is information relating to the conditions of the vehicle such as the speed of the vehicle, the remaining fuel amount, water temperature, and oil temperature.
The information generated according to the travel of the vehicle as described above can be displayed as a virtual image that is located at a distance of about 10 to 200 m from the driver, that is, a long-distance virtual image. The distance from the driver to the long-distance virtual image desirably changes along with the travel of the vehicle. The information constantly displayed during the running of the vehicle can be displayed at a distance of about two to three meters from the driver, that is, a short-distance virtual image. The distance from the driver to the short-distance virtual image is desirably constant regardless of the travel of the vehicle.
However, in the vehicle HUD device described in PTL 1, all the plurality of screens is movable and thus the display distances of all the virtual images change. In particular, when the display distance of the information relating to the conditions of the vehicle changes, the driver has a difficulty in visually recognizing the information. For example, the driver may mistake the information relating to the conditions of the vehicle for information included in the foreground in the forward field of view.
Thus, the inventors of the present invention have contemplated using two screens, that is, a movable screen for forming a long-distance virtual image and a fixed screen for forming a short-distance virtual image. However, the distance between the driver and the screen necessary for forming a virtual image greatly varies between a case of a long-distance virtual image and a case of a short-distance virtual image. For example, the inventors of the present invention have found that, in order to obtain a clear virtual image in both the cases, there is a problem that the HUD needs to be increased in size to a degree that the HUD cannot be mounted in a vehicle. In addition, when the two screens are scanned with scanning light projected from one light source, the distances between the scan unit as a scanning light emission unit and the screens are greatly different, so that the spot diameter of the scanning light varies between the screens and the resolutions of the images formed on the screens are greatly different. Accordingly, the inventors of the present invention have found that configuration of the scan unit to minimize the spot diameter on the long-distance screen causes a problem that the spot diameter on the short-distance screen becomes large and the resolution of the short-distance virtual image becomes lower. In addition, the inventors of the present invention have found that scanning two screens with scanning light projected from one light source causes a problem that unnecessary light mixes into the virtual image or the virtual image becomes unclear due to influence of the scanning light leaking from between the two screens, or influence of the scanning light diffused at screen end faces between the two screens. The inventors of the present invention have found a technique for making an image to be displayed clear as described below.
A display device according to an aspect of the present disclosure is a display device that displays a virtual image by forming an image onto a display medium and includes a light source unit, a screen, a self-emitting display unit, a scan unit, the screen, and a drive unit. The light source unit emits light. The screen is movably disposed on an optical path from the light source unit to the display medium. The self-emitting display unit is disposed adjacent to the optical path. The scan unit scans the screen with the light emitted from the light source unit. The drive unit moves the screen along the optical path. The screen is disposed to project an image imaged on the screen by scanning of the scan unit onto the display medium, and the self-emitting display unit is disposed to project an image generated by the self-emitting display unit onto the display medium.
According to the foregoing aspect, two images projected from the screen and the self-emitting display unit onto the display medium are reflected on the display medium and arrive at the eyes of a person viewing the display medium. At this time, the person visually recognizes two virtual images of the two images on an opposite side of the display medium. Each of display distances of the two virtual images depends on a distance along an optical path from the display medium to the screen and a distance along an optical path from the display medium to the self-emitting display unit. The screen and the self-emitting display unit do not affect quality of images generated by the screen and the self-emitting display unit. Accordingly, it is possible to obtain two clear virtual images by positioning the screen and the self-emitting display unit so as to match respective display distances required for the two virtual images. The scan unit does not need to scan the self-emitting display unit but needs to scan only the screen, so that it is possible to shallow a focal depth of a light beam emitted from the scan unit. Accordingly, a spot diameter of the light on the screen becomes small, so that it is possible to improve the resolution of the virtual image.
In the display device according to an aspect of the present disclosure, the screen and the self-emitting display unit may be disposed to partially overlap each other as seen from a direction along the optical path. According to the foregoing aspect, it is possible to reduce a gap between the image projected from the screen and the image projected from the self-emitting display unit. This reduces leakage of the scanning light from the scan unit through the gap.
In the display device according to an aspect of the present disclosure, the scan unit may be disposed such that the spot diameter becomes minimum at an almost center position in a movement range of the screen. According to the foregoing aspect, a maximum spot diameter in the movement range of the screen can be decreased, so that the spot diameter of the light on the screen becomes small, and accordingly, the resolution of the image is enhanced. This achieves improvement in the resolution of the virtual image.
In the display device according to an aspect of the present disclosure, an image projected from the screen onto the display medium and an image projected from the self-emitting display unit onto the display medium may be adjacent to each other. According to the foregoing aspect, it is possible to decrease eye movement for visually recognizing a virtual image of the image projected from the screen and a virtual image of the image projected from the self-emitting display unit. This makes it easy to visually recognize the two virtual images.
The display device according to an aspect of the present disclosure may further include an optical system that is disposed on the optical path between the screen and the display medium. The optical system may project the image projected from the screen onto the display medium in a changed projection direction. According to the foregoing aspect, it is possible to increase the display distance of the virtual image corresponding to the distance from the display medium to the screen along the optical path while suppressing upsizing of the display device.
The display device according to an aspect of the present disclosure may be mounted on a movable body, an image imaged on the screen may be an image temporarily displayed along with travel of the movable body, and an image generated by the self-emitting display unit may be an image continuously displayed. According to the foregoing aspect, a display distance of a virtual image of the image continuously generated by the self-emitting display unit remains unchanged, which facilitates adjustment of eye focus for visually recognizing the virtual image continuously displayed, thereby making it easy to visually recognize the virtual image. A virtual image of the image imaged on the movable screen can be three-dimensionally represented with depth, for example. This makes it possible to form and display a three-dimensional virtual image along with the travel of the movable body. Such a virtual image is suitable for superimposition on the foreground in a traveling direction of the movable body.
In the display device according to an aspect of the present disclosure, the self-emitting display unit may be a flat panel display. The self-emitting display unit may have a light-guiding member that is disposed on a side opposite to a display surface of an image and a light source that projects light onto an edge of the light-guiding member. According to the foregoing aspect, it is possible to reduce an occupied space on a rear side of a display surface of the self-emitting display unit. This suppresses interference between constituent elements on the rear side of the self-emitting display unit and the screen in motion. Further, it is possible to decrease the distance between the self-emitting display unit and the screen, thereby achieving downsizing of the display device.
It should be noted that the comprehensive or specific aspects of the display device may be implemented by a system, a method, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM, or may be implemented by any combination of a system, a method, an integrated circuit, a computer program, and a recording medium.
Hereinafter, a display device according to exemplary embodiment will be described with reference to the drawings. It should be noted that the display device according to the exemplary embodiment, which will be described below, provides comprehensive or specific examples of the present invention. Numerical values, shapes, materials, constituent elements, arrangement positions and connection modes of the constituent elements, steps, order of the steps, and the like illustrated in the following exemplary embodiment are merely examples, and therefore are not intended to limit the present disclosure. Among the constituent elements in the exemplary embodiment described below, constituent elements which are not described in the independent claims showing the top level concept are described as arbitrary constituent elements.
A schematic configuration of display device 10 according to an exemplary embodiment will be described with reference to
As illustrated in
As illustrated in
Referring to
For example, display device 10 displays in region D1 the first virtual image with a change in the display distance according to travel of vehicle 300. The first virtual image includes an intersection to be turned, a distance to the intersection, a direction of right or left turn, a direction to be traveled or a lane, other vehicles, obstacles, and others. A temporary image can be displayed as a virtual image in region D1. Display device 10 also displays in region D2 the second virtual image as information about the conditions of the vehicle in a constant state regardless of the travel of vehicle 300, for example, without changing shape, dimensions, and position. Information to be constantly displayed during running of the vehicle is displayed in region D2, and the information can be constantly displayed in region D2.
A detailed configuration of display device 10 according to the exemplary embodiment will be described with reference to
Referring to
Light source unit 110 emits light for forming a virtual image. The light emitted from light source unit 110 is projected onto windshield 201, that is, display medium 200, thereby to form a virtual image visually recognizable by driver A. For example, light source unit 110 is configured by a projector that includes semiconductor laser light sources that emit red (R), green (G), and blue (B) light as light emitting bodies. This projector enables formation of a highly recognizable virtual image regardless of objects around vehicle 300, body color of vehicle 300, and brightness of surroundings of vehicle 300. Display device 10 including the semiconductor laser light sources enables a compact configuration, so that it is possible to minimize a space of dashboard 301 occupied by display device 10.
Scanner 120 is arranged on the optical path of light emitted from light source unit 110. Scanner 120 emits the light received from light source unit 110 as scanning light onto screen 130 to scan screen 130 with the scanning light. Scanner 120 can emit the light received as scanning light in an arbitrary direction, which is implemented by a micro electro mechanical systems (MEMS) mirror, for example. The scanning light from scan unit 120 images an image to be displayed as a virtual image on screen 130. The scanning of screen 130 by scan unit 120 may be two-dimensional scanning, for example, raster scanning by which horizontal scanning is gradually shifted to a vertical direction.
In the present exemplary embodiment, screen 130 is a rectangular plate-, sheet-, or film-shaped member, but the shape of screen 130 is not limited to the foregoing ones. Screen 130 is configured such that light having arrived at screen 130 can form an image on screen 130. In the present exemplary embodiment, screen 130 is configured by a light-transmissible member but may be configured by a light-reflecting member. Screen 130 capable of light transmission is configured by a semi-transparent member, for example. Screen 130 may be a diffusing screen, for example. Screen 130 projects onto optical system 160 the image imaged by the scanning light from scan unit 120 on screen 130.
Screen 130 is disposed within an irradiation range of the scanning light from scan unit 120, that is, a scanning range. Screen 130 can reciprocate in parallel along overall optical path L of the scanning light as shown by a void arrow in
Drive unit 150 causes screen 130 to reciprocate in parallel to the direction described above according to a signal from controller 100 described later. Drive unit 150 is configured by an electromagnetic, hydraulic, or ultrasonic actuator, for example.
Self-emitting display unit 140 emits light by itself to display an image. Self-emitting display unit 140 includes a display, for example. Specifically, self-emitting display unit 140 may be a liquid crystal display (LCD) or a flat panel display (FPD) such as an organic or inorganic electro luminescence (EL) display. Self-emitting display unit 140 displays information to be displayed such as information indicating the conditions of vehicle 300 according to the signal from controller 100. A display surface of self-emitting display unit 140 is directed to optical system 160. A display image on self-emitting display unit 140 is projected onto display medium 200 via optical system 160.
Optical system 160 projects onto region D of windshield 201 as display medium 200 the images projected by screen 130 and self-emitting display unit 140 onto optical system 160. Optical system 160 may include a reflecting mirror that reflects light, a lens that enlarges or contracts light to be transmitted, and the like. In the present exemplary embodiment, optical system 160 includes a reflecting mirror such as a concave mirror or a plane mirror. Specifically, optical system 160 includes two reflecting mirrors 160a and 160b as illustrated in
An image on screen 130 and an image on self-emitting display unit 140 are projected onto first reflecting mirror 160a. Each of the images is reflected and enlarged by first reflecting mirror 160a, and is projected onto second reflecting mirror 160b. Each of the images is further reflected and enlarged again by second reflecting mirror 160b, and is projected onto display medium 200. Use of reflecting mirrors 160a and 160b allows the images to be projected onto desired directions in an enlarged state. Display medium 200 as windshield 201 forms a curved display surface. However, use of reflecting mirrors 160a and 160b as curved mirrors makes it possible to adjust a distortion of an image projected onto the display surface. An orientation of an image after reflection on the concave mirror can change 180° with respect to the image before reflection. However, use of two reflecting mirrors 160a and 160b makes it possible to suppress a change in the orientation of an image caused by the reflection. Optical system 160 may include a lens, and the lens may enlarge an image and adjust an orientation of the image. All or some components of optical system 160 may be included in display device 10 as constituent elements.
Controller 100 controls entire display device 10. For example, controller 100 acquires information from an external device, and calculates an image to be displayed as a virtual image and a position of the image based on the acquired information. The external device may be a car navigation system, a speed meter, a water temperature meter, a human body detector, an eye location detector, an obstacle detector, or the like mounted in a vehicle, for example. Controller 100 outputs information indicating calculation results as a signal to light source unit 110 to control light emission of light source unit 110. Controller 100 also outputs control signals to scan unit 120 and drive unit 150 to control operations of scan unit 120 and screen 130. Based on the information acquired from the external device, controller 100 causes self-emitting display unit 140 to display information to be displayed. Controls of light source unit 110, scan unit 120, drive unit 150, and self-emitting display unit 140 may be independently performed but may include adjustments of synchronization among these components, and the like. Controller 100 may be configured by a computer system (not illustrated) including a central processing unit (CPU), a random access memory (RAM), a read-only memory (ROM), and others. All or some of functions of controller 100 may be implemented by execution of programs recorded on the ROM by the CPU using the RAM as a working memory. In addition, all or some of the functions of controller 100 may be implemented by a dedicated hardware circuit. Controller 100 may be configured by a single constituent element that performs a centralized control, or may be configured by a plurality of constituent elements performing a decentralized control in cooperation. In the present exemplary embodiment, controller 100 is a constituent element of display device 10 but may be a constituent element of the external device.
In display device 10 configured as described above, an image imaged by the scanning light on screen 130 and an image displayed by self-emitting display unit 140 are projected onto optical system 160, and the projected images are changed in orientation and enlarged by optical system 160 and projected onto windshield 201 as display medium 200. The image imaged on screen 130 is projected onto region D1 in windshield 201 illustrated in
A beam diameter of the scanning light emitted from lens 120a gradually becomes small with decreasing proximity to lens 120a, then becomes minimum at a beam waist, and then gradually becomes large. In the present exemplary embodiment, although not limited, scan unit 120 is disposed with respect to screen 130 such that the beam waist of the scanning light is positioned in an almost middle, that is, in a center of the predetermined movement range of screen 130 as seen in overall optical path L. Accordingly, when screen 130 is located at position S1 nearest scan unit 120 and is located at position S2 farthest from scan unit 120, a spot diameter of the scanning light on screen 130 becomes maximum. When screen 130 is located at middle position S3 between position S1 and position S2 within the predetermined movement range, the spot diameter of the scanning light on screen 130 becomes minimum. When screen 130 is positioned within the predetermined movement range, a focal depth of the scanning light may be shallow, which suppresses a maximum spot diameter of the scanning light.
Self-emitting display unit 140 in a plate shape is adjacent to overall optical path L. Self-emitting display unit 140 is positioned along overall optical path L. Further, self-emitting display unit 140 is positioned more distant from scan unit 120 than screen 130 along overall optical path L, that is, in proximity to first reflecting mirror 160a. Accordingly, in overall optical path L, self-emitting display unit 140 is positioned nearer the eyes of driver A than screen 130. Self-emitting display unit 140 has display surface 140a oriented toward first reflecting mirror 160a. Self-emitting display unit 140 is partially opposed to second main surface 130b of screen 130. Second main surface 130b is a surface of screen 130 opposite to first main surface 130a. In the present exemplary embodiment, although not limited, self-emitting display unit 140 is disposed approximately parallel to screen 130. When screen 130 is seen from scan unit 120 along overall optical path L, edge 130c as a portion of a peripheral edge of screen 130 and area M adjacent to edge 130c of screen 130 overlap self-emitting display unit 140. When screen 130 is seen from scan unit 120 along overall optical path L, edge 130c constitutes a peripheral edge of screen 130 adjacent to self-emitting display unit 140.
Scanner 120 can scan entire first main surface 130a of screen 130 by arbitrarily changing the direction of the scanning light. Screen 130 and self-emitting display unit 140 overlap each other in area M, which suppresses the scanning light from leaking from edge 130c between screen 130 and self-emitting display unit 140 and reaching first reflecting mirror 160a. In addition, this suppresses the scanning light from diffusing from edge 130c and reaching first reflecting mirror 160a.
In scan unit 120 of the present exemplary embodiment, the focal depth of the scanning light emitted from lens 120a corresponds to a movement distance of screen 130 between positions S1 and S2. For example, when self-emitting display unit 140 is a screen as well, the focal depth of the scanning light corresponds to a distance between screen 130 at position S1 and the screen in place of self-emitting display unit 140. In the latter case, the focal depth of the scanning light becomes large, and thus the spot diameter of the scanning light on the screen in place of self-emitting display unit 140 increases to deteriorate resolution of the image. In the present exemplary embodiment, scan unit 120 scans only screen 130, and therefore disposition of scan unit 120 and screen 130 to be scanned can be determined such that spot diameters of all the light become optimum.
The images on screen 130 and self-emitting display unit 140 that partially overlap each other as described above are respectively displayed in regions D1 and D2 on windshield 201 as illustrated in
Referring to
Images P1 and P2 are formed as described below, for example. A human body detector (not illustrated) mounted in vehicle 300 detects a person existing in a range of a constant distance from vehicle 300, and acquires information on a position of the person. Various known methods such as using a camera or millimeter-wave radar, for example, are applicable to the detection of a person and the acquisition of information on the position of the person. Further, an eye location detector (not illustrated) mounted in vehicle 300 detects motion of the eyes of driver A and acquires information on line of sight. Various known methods such as using a camera or infrared rays, for example, are applicable to the detection of motion of the eyes of driver A and the acquisition of the information on the line of sight. Based on results of detection by the human body detector and the eye location detector, display device 10 calculates positions of images P1 and P2 such that the virtual images of images P1 and P2 overlap the pedestrians, and displays images P1 and P2 at the positions.
Image P3 is formed as described below, for example. A car navigation system (not illustrated) mounted in vehicle 300 determines a route to an input destination. Then, based on information on a decided path, the car navigation system determines guidance information to be displayed relating to the traveling route along with the travel of vehicle 300. Further, the eye location detector detects motion of the eyes of driver A and acquires information on the line of sight. Based on the guidance information and the results of the detection by the eye location detector, display device 10 calculates a position of image P3 such that the virtual image of image P3 is visually recognized to overlap the left-turn point or in front of the left-turn point, and displays image P3 at that position. Image P3 is three-dimensionally formed such that the virtual image has a depth in the traveling direction of vehicle 300, that is, such that the display distance of the virtual image increases continuously.
Hereinafter, an image generation operation by scan unit 120 and screen 130 will be described. Referring to
While screen 130 reciprocates within the predetermined movement range, scan unit 120 projects the scanning light to image an image on screen 130. When the thus formed image is projected onto display medium 200, the virtual image of the projected image is visually recognized by driver A as a virtual image varying in display distance among portions. For example, when screen 130 is located within the predetermined movement range at position S1 most distant from display medium 200 along overall optical path L, scan unit 120 scans screen 130 near edge 130d with scanning light along edge 130d. Edge 130d is an edge opposite to edge 130c and self-emitting display unit 140. Position S2 of screen 130 is a position nearest display medium 200 along overall optical path L within the predetermined movement range. As screen 130 comes closer to display medium 200 along overall optical path L, screen 130 scans edge 130d in a direction along edge 130d while bringing the scanning position closer to edge 130c. The thus imaged image is projected onto region D1 of display medium 200. The projected image is visually recognized by driver A as a virtual image of which the display distance becomes long from downward to upward in a direction from region D2 to region D1.
Although not limited, in the present exemplary embodiment, screen 130 is reciprocated and vibrated at a high speed along overall optical path L between positions S1 and S2. At that time, screen 130 vibrates at a frequency of 60 Hz, for example. Scanner 120 also scans screen 130 at a high speed along with movement of screen 130. In a period during which screen 130 is making an outward movement from position S1 to position S2, scan unit 120 scans screen 130 from edge 130d to edge 130c. In a period during which screen 130 is making a return movement from position S2 to position S1, scan unit 120 scans screen 130 from edge 130c to edge 130d. Accordingly, a one-frame image is imaged on screen 130 by each of the outward movement and the return movement. Then, video of the virtual images changing in display distance is displayed by images of 120 frames formed per second.
For example, image P3 illustrated in
The frequency of vibration of screen 130 is not limited to 60 Hz. The frequency of vibration of screen 130 may be a frequency at which updating of frames by scanning corresponding to the frequency is not recognized as flicker by a human's eyes. For example, when images are updated at a rate of 60 frames per second, motion of moving images can be recognized as smooth by a viewing person. The frequency of vibration may not be constant. For example, the frequency may be temporarily lowered during the movement of vehicle 300. For example, a virtual image based on an image imaged at a lowered frequency appears to be shallow in depth to driver A as compared to a virtual image based on an image imaged on screen 130 moving at a usual frequency. Screen 130 may be stopped temporarily or intermittently. In this case, a virtual image is formed to appear to stand vertically to driver A. For example, each of images P1 and P2 not requiring a sense of depth may be displayed as such a virtual image.
When display device 10 is used as a vehicle HUD as in the present exemplary embodiment, external light such as sunlight may enter and travel backward in overall optical path L. Specifically, the external light may pass through windshield 201 and enter the interior of the vehicle, and then reflect on optical system 160 and reach screen 130 and self-emitting display unit 140. The external light illuminates entire screen 130 and self-emitting display unit 140 to reduce a difference in brightness of light between screen 130 and self-emitting display unit 140, thereby degrading contrast of a virtual image. In a case where the external light is sunlight in particular, infrared rays may raise the internal temperature of display device 10 and ultraviolet rays may deteriorate components of screen 130, self-emitting display unit 140, and others. To avoid these problems, optical system 160 may be at least partially coated such that optical system 160 transmits only light with a specific wavelength as a whole. Use of a laser light source with a narrow wavelength spectral width of light as light source unit 110 in combination with optical system 160 allows optical system 160 to transmit more efficiently ultraviolet light, infrared light, and yellow light unnecessary for displaying a virtual image.
For example, reflecting mirrors 160a and 160b such as concave mirrors constituting optical system 160 may have light transmission characteristics as illustrated in
As a specific example, the foregoing characteristics may be imparted to at least one of reflecting mirrors 160a and 160b illustrated in
Also in this case, the first mirror preferably has a larger area than the second mirror. A mirror to transmit visible light is produced using a dielectric multi-layer film, for example, so that it takes a higher manufacturing cost. Therefore, use of the second mirror smaller in area makes it possible to obtain an effect of suppressing the manufacturing cost. In addition, a mirror to transmit infrared light and ultraviolet light has a larger heat absorption amount, and thus transmission of infrared light and ultraviolet light through the mirror larger in area makes it possible to obtain an effect of suppressing a temperature rise.
Operations of display device 10 will be described with reference to
In the present exemplary embodiment, display device 10 constantly displays in region D2 information about the conditions of a vehicle not relating to the travel of vehicle 300, changes in the foreground through windshield 201, and others. Display device 10 keeps the display distance of the virtual image in region D2 visually recognized by driver A constant. Driver A can visually recognize the virtual image of the vehicle information displayed in region D2 at the same distance all the time and can easily adjust the focus of the eyes, so that it is possible to suppress false recognition of the vehicle information. Display device 10 temporarily displays in region D1 information varying along with the travel of vehicle 300 and changes in the foreground through windshield 201 as necessary. Display device 10 changes the display distance of the virtual image in region D1 visually recognized by driver A according to a distance from driver A to a target providing the information, for example. Further, display device 10 changes the display distance of the virtual image in region D1 visually recognized by driver A according to a speed of vehicle 300. Accordingly, driver A can visually recognize the virtual image of the information displayed in region D1 in a state of being superimposed on the foreground through windshield 201. Driver A can visually recognize nearby the vehicle information constantly displayed in region D2, so that it is possible to suppress false recognition of the vehicle information.
Display device 10 according to the exemplary embodiment of the present disclosure displays a virtual image by projecting an image onto display medium 200. Display device 10 includes light source unit 110 that emits light; screen 130 that is movably disposed on an optical path from light source unit 110 to display medium 200; self-emitting display unit 140 that is disposed adjacent to the optical path; scan unit 120 that scans screen 130 with the light emitted from light source unit 110; and drive unit 150 that moves screen 130 along the optical path. Screen 130 is disposed to project an image imaged on screen 130 by scanning of scan unit 120 onto display medium 200, and self-emitting display unit 140 is disposed to project an image generated by self-emitting display unit 140 onto display medium 200.
In the foregoing configuration, two images projected from screen 130 and self-emitting display unit 140 onto display medium 200 are reflected on display medium 200 and arrive at the eyes of a person viewing display medium 200. At this time, the person visually recognizes two virtual images of the two images on an opposite side of display medium 200. Each of the display distances of the two virtual images depends on a distance along an optical path from display medium 200 to screen 130 and a distance along an optical path from display medium 200 to self-emitting display unit 140. Screen 130 and self-emitting display unit 140 do not affect quality of images generated by screen 130 and self-emitting display unit 140. Accordingly, it is possible to obtain two clear virtual images by positioning screen 130 and self-emitting display unit 140 so as to match respective display distances required for the two virtual images. Scan unit 120 does not need to scan self-emitting display unit 140 but needs to scan only screen 130, so that it is possible to shallow a focal depth of a light beam emitted from scan unit 120. Accordingly, a spot diameter of the light on screen 130 becomes small, so that it is possible to improve the resolution of the virtual image.
In display device 10 according to the exemplary embodiment, screen 130 and self-emitting display unit 140 are disposed to partially overlap each other as seen from a direction along the optical path. In the foregoing configuration, it is possible to reduce a gap between the image projected from screen 130 and the image projected from self-emitting display unit 140. This reduces leakage of the scanning light of scan unit 120 through the gap.
In display device 10 according to the exemplary embodiment, scan unit 120 is disposed such that the spot diameter becomes minimum at an almost center position in a movement range of screen 130. In the foregoing configuration, a maximum spot diameter in the movement range of screen 130 can be decreased, so that the spot diameter of the light on screen 130 becomes small, and accordingly, the resolution of the image is enhanced. This achieves improvement in the resolution of the virtual image.
In display device 10 according to the exemplary embodiment, an image projected from screen 130 onto display medium 200 and an image projected from self-emitting display unit 140 onto display medium 200 are adjacent to each other. In the foregoing configuration, it is possible to decrease eye movement for visually recognizing a virtual image of the image projected from screen 130 and a virtual image of the image projected from self-emitting display unit 140. This makes it easy to visually recognize the two virtual images.
Display device 10 according to the exemplary embodiment further includes optical system 160 that is disposed on the optical path between screen 130 and display medium 200. Optical system 160 projects the image projected from screen 130 onto display medium 200 in a changed projection direction. According to the foregoing configuration, it is possible to increase the display distance of the virtual image corresponding to the distance from display medium 200 to screen 130 along the optical path while suppressing upsizing of display device 10.
Display device 10 according to the exemplary embodiment is mounted on vehicle 300 as a movable body. An image formed on screen 130 is an image temporarily displayed along with travel of vehicle 300, and an image generated by self-emitting display unit 140 is an image continuously displayed. In the foregoing configuration, a display distance of a virtual image of the image continuously generated by self-emitting display unit 140 remains unchanged, which facilitates adjustment of eye focus for visually recognizing the virtual image continuously displayed, thereby making it easy to visually recognize the virtual image. A virtual image of the image imaged on movable screen 130 can be three-dimensionally represented with depth, for example. This makes it possible to form and display a three-dimensional virtual image along with the travel of the movable body. Such a virtual image is suitable for superimposing on the foreground in a traveling direction of the movable body.
The display device according to the exemplary embodiment has been described as an example of a technique disclosed in the present application. However, the present disclosure is not limited to the exemplary embodiment. The technique in the present disclosure is also applicable to modifications of the exemplary embodiment in which change, replacement, addition, or omission is made as appropriate, or other exemplary embodiments. In addition, new exemplary embodiments or modifications can be made by combining constituent elements in the exemplary embodiment.
As described above, the comprehensive or specific aspects of the present disclosure may be implemented by a system, a method, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM. Moreover, the comprehensive or specific aspects of the present disclosure may be implemented by any combination of a system, a method, an integrated circuit, a computer program, and a recording medium.
For example, processing units included in the display devices according to the exemplary embodiment described above are typically implemented as large-scale integration (LSI) circuits. Each of the circuits may be integrated into one chip, or some or all of the circuits may be integrated into one chip.
The circuit integration is not limited to the LSI, and may be achieved by a dedicated circuit or a general-purpose processor. There may be used: a field programmable gate array (FPGA) programmable after the LSI is fabricated; or a reconfigurable processor in which connections and settings of circuit cells in the LSI are reconfigurable.
In the above exemplary embodiments, the constituents may be implemented by dedicated hardware or by execution of software programs individually suitable for the constituents. The constituent elements may be implemented by a program execution section, such as a CPU or a processor, reading and executing software programs stored in a recording medium, such as a hard disk or a semiconductor memory.
The division of the functional block in the block diagram is only by way of example, and a plurality of functional blocks may be implemented as one functional block, one functional block may be divided into a plurality of functional blocks, or a part of the functions may be transferred to another functional block. Functions of a plurality of functional blocks having similar functions may be processed in parallel or in a time division manner by single piece of hardware or software.
In display device 10 according to the exemplary embodiment, self-emitting display unit 140 is disposed between first reflecting mirror 160a and screen 130, but the present disclosure is not limited to this. For example, self-emitting display unit 140 may be disposed between first reflecting mirror 160a and second reflecting mirror 160b to display an image to second reflecting mirror 160b. Alternatively, self-emitting display unit 140 may be disposed between display medium 200 and first reflecting mirror 160a to display an image to display medium 200. These configurations make it possible to shorten the distance between self-emitting display unit 140 and display medium 200 and reduce the display distance of the virtual image in region D2. That is, driver A can visually recognize nearby the virtual image in region D2. For example, when the display distance required for the virtual image in region D2 is longer than the display distance required for the virtual image in region D1, shortening the distance between self-emitting display unit 140 and display medium 200 as described above is effective.
In display device 10 according to the exemplary embodiment, when self-emitting display unit 140 is an LCD, light source 141 may be provided as a backlight for irradiating self-emitting display unit 140 with light on the side opposite to display surface 140a as illustrated in
In self-emitting display unit 140 illustrated in
The display device according to one aspect has been described above based on the exemplary embodiment, but the present disclosure is not limited to the exemplary embodiment. Configurations in which various variations conceived by those skilled in the art are applied to the present exemplary embodiment, and configurations constructed by combining the constituent element in different exemplary embodiments may also fall within the scope of one aspect without departing from the spirit of the present disclosure.
The present disclosure can be applied to a display device that displays a virtual image by using a display medium.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-007124 | Jan 2017 | JP | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2018/000603 | Jan 2018 | US |
| Child | 16508280 | US |
