Display device and display system

Abstract

A display device according to the present disclosure is mounted on a vehicle, and comprises a first display device that is disposed near the driver seat and a second display device that is disposed near the front passenger seat. The first display device projects, as a virtual image in the driver's field of view, an image in which the rear view on the driver seat side is captured. The second display device projects, as a real image in the driver's field of view, an image in which the rear view on the front passenger seat side is captured.

Description

Display device and display system

[0001] The present disclosure relates to a display device and a display system.

[0002] Various display systems also known as electronic side mirrors have been proposed. For example, Patent Document 1 discloses a display system including a left-side imaging device that captures an image of the left rear side of a vehicle, a right-side imaging device that captures an image of the right rear side of the vehicle, a left-side display device that allows the driver to view the image captured by the left-side imaging device as a left-side virtual image, and a right-side display device that allows the driver to view the image captured by the right-side imaging device as a right-side virtual image.

[0003] Japanese Patent Application Publication No. 2020-114697

[0004] The display device of the present disclosure is a display device mounted on a vehicle, and comprises a first display device arranged near the driver's seat and a second display device arranged near the passenger seat, wherein the first display device projects an image of the area behind the driver's seat as a virtual image into the driver's field of view, and the second display device projects an image of the area behind the passenger's seat as a real image into the driver's field of view.

[0005] The display system of the present disclosure is a display system mounted on a vehicle, and comprises: a first imaging device that captures an image of the area behind the driver's seat; a second imaging device that captures an image of the area behind the passenger's seat; a first display device arranged near the driver's seat; a second display device arranged near the passenger's seat; and a control device, wherein the control device controls the first display device to project an image captured by the first imaging device as a virtual image within the driver's field of view, and controls the second display device to project an image captured by the second imaging device as a real image within the driver's field of view.

[0006] The display system of the present disclosure is a display system mounted on a vehicle, comprising: a first imaging device that captures an image of the area behind the driver's seat; a second imaging device that captures an image of the area behind the passenger's seat; a first display device arranged near the driver's seat; a second display device arranged near the passenger's seat; and a control device, wherein the control device controls the first display device to project an image captured by the first imaging device as a first virtual image within the driver's field of view; and controls the second display device to project an image captured by the second imaging device as a second virtual image within the driver's field of view, and when the distance between the driver's eyes and the first virtual image is a first distance, the distance between the driver's eyes and the second virtual image is a second distance, the distance between the driver's eyes and the first display device is a third distance, and the distance between the driver's eyes and the second display device is a fourth distance, the control device controls the first display device and / or the second display device so that the difference between the first distance and the third distance is greater than or equal to the difference between the second distance and the fourth distance.

[0007] The display device of the present disclosure is a display device mounted on a vehicle, comprising: a first display device arranged near the driver's seat; and a second display device arranged near the passenger seat, wherein the first display device projects an image of the area behind the driver's seat as a first image into the driver's field of view; and the second display device projects an image of the area behind the passenger's seat as a second image into the driver's field of view, and when the distance between the driver's eyes and the first image is a first distance, the distance between the driver's eyes and the second image is a second distance, the distance between the driver's eyes and the first display device is a third distance, and the distance between the driver's eyes and the second display device is a fourth distance, the first display device and / or the second display device sets the difference between the first distance and the third distance to be greater than or equal to the difference between the second distance and the fourth distance.

[0008] FIG. 1 is a schematic diagram showing an example of a display system according to an embodiment of the present disclosure. FIG. 2 is a diagram showing the interior of a vehicle equipped with the display system of FIG. 1. FIG. 3 is a top view showing a vehicle equipped with the display system of FIG. 1. FIG. 4 is a diagram showing an example of an optical system in the display system of FIG. 1. FIG. 5 is a diagram showing an example of an optical system in the display system of FIG. 1. FIG. 6 is a diagram for explaining projection positions of a virtual image and a real image in the display system of FIG. 1. FIG. 7 is a diagram showing another example of the optical system in the display system of FIG. 1. FIG. 8 is a diagram showing yet another example of the optical system in the display system of FIG. 1. FIG. 9 is a diagram for explaining another example of the display system according to an embodiment of the present disclosure. FIG. 10 is a diagram for explaining yet another example of the display system according to an embodiment of the present disclosure.

[0009] In conventional display systems, the distance from the driver's eyes to the left virtual image is different from the distance from the driver's eyes to the right virtual image, making it difficult for the driver to see the left and right virtual images.

[0010] According to the present disclosure, the driver can easily view the image that shows the area behind the driver's seat side and the image that shows the area behind the passenger's seat side.

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The drawings used in the following description are schematic, and the dimensional ratios and the like in the drawings do not necessarily correspond to the actual ones. The drawings used in the following description show the main components of a display system of the present disclosure. The display system of the present disclosure may include well-known components not shown, such as a camera that captures an image of the driver's face. In addition, in some of the drawings, a Cartesian coordinate system XYZ is defined for convenience. The X-axis direction is also referred to as the width direction. The Y-axis direction is also referred to as the height direction. The Z-axis direction is also referred to as the depth direction or the emission direction.

[0012] FIG. 1 is a schematic diagram illustrating an example of a display system according to an embodiment of the present disclosure, FIG. 2 is a diagram illustrating the interior of a vehicle equipped with the display system of FIG. 1 , and FIG. 3 is a top view illustrating a vehicle equipped with the display system of FIG. 1 . FIGS. 4A and 4B are diagrams illustrating an example of an optical system in the display system of FIG. 1 , and FIG. 5 is a diagram for explaining the projection positions of a virtual image and a real image in the display system of FIG. 1 . FIGS. 6A and 6B are diagrams illustrating another example of the optical system in the display system of FIG. 1 , and FIGS. 7A and 7B are diagrams illustrating yet another example of the optical system in the display system of FIG. 1 . FIG. 8 is a diagram for explaining another example of a display system according to an embodiment of the present disclosure, and FIG. 9 is a diagram for explaining yet another example of a display system according to an embodiment of the present disclosure. In FIGS. 4A, 4B, 6A, 6B, 7A, and 7B, for ease of illustration, the optical paths of image light incident on a semi-transparent mirror and the optical paths of image light reflected by the semi-transparent mirror are shown shifted in the Y-axis direction.

[0013] 1, a display system 50 of this embodiment includes a display device 30, a first imaging device 1, a second imaging device 2, and a control device 5. In the following description, when the first imaging device 1 and the second imaging device 2 are not to be distinguished from each other, they may be referred to as imaging devices 1 and 2.

[0014] The display system 50 may be mounted on a mobile object 9. The mobile object 9 may be a vehicle. Vehicles may include, for example, automobiles, industrial vehicles, rail vehicles, residential vehicles, and fixed-wing aircraft traveling on runways. Automobiles may include, for example, passenger cars, trucks, buses, motorcycles, and trolleybuses. Industrial vehicles may include, for example, agricultural and construction industrial vehicles. Industrial vehicles may include, for example, forklifts and golf carts. Agricultural industrial vehicles may include tractors, cultivators, transplanters, binders, combine harvesters, and lawn mowers. Construction industrial vehicles may include, for example, bulldozers, scrapers, excavators, cranes, dump trucks, and road rollers. Vehicles may include manually propelled vehicles. Vehicle classifications are not limited to the above examples. For example, automobiles may include industrial vehicles capable of traveling on roads. The same vehicle may be included in multiple classifications. The following description will be given of the case where the mobile object 9 is a vehicle, particularly a passenger car.

[0015] The display device 30 includes a first display device 3 and a second display device 4 .

[0016] 2 and 3 , the first display device 3 is disposed near the driver's seat of the vehicle 9. The first display device 3 may be disposed on the A-pillar 9a on the driver's seat side. The first display device 3 may be disposed at or near the lower end of the A-pillar 9a on the driver's seat side. The first display device 3 may be disposed in or on the dashboard. The first display device 3 may be disposed at or near the end of the driver's seat side on the dashboard.

[0017] As shown in Figures 2 and 3, the second display device 4 is arranged near the passenger seat of the vehicle 9. The second display device 4 may be arranged on the A-pillar 9b on the passenger side. The second display device 4 may be arranged at or near the lower end of the A-pillar 9b on the passenger side. The second display device 4 may be arranged in or on the dashboard. The second display device 4 may be arranged at or near the end of the passenger side on the dashboard. The second display device 4 may be located farther from the eyes of the driver 12 than the first display device 3.

[0018] The first display device 3 projects an image of the area behind the driver's seat side as a virtual image V into the field of view of the driver 12. The second display device 4 projects an image of the area behind the passenger seat side as a real image R into the field of view of the driver 12. In this specification, the image may be a moving image (also referred to as a video).

[0019] In a vehicle using mirror-type door mirrors, the distance between the driver's 12's eyes and the driver's side door mirror is different from the distance between the driver's 12's eyes and the passenger's side door mirror, which can make it difficult for the driver 12 to see the image reflected in the driver's side door mirror or the passenger's side door mirror. The display device 30 can reduce the difference between the distance between the driver's 12's eyes and the virtual image V and the distance between the driver's 12's eyes and the real image R. As a result, the driver 12 can more easily see the virtual image V and the real image R, improving driving safety.

[0020] The control device 5 is connected to and controls each component of the display system 50. The control device 5 and each component of the display system 50 may be connected via wired and / or wireless communication, or may be connected to each other via an in-vehicle network such as a control area network (CAN). The control device 5 may be configured to include one or more processors. The processor may include a general-purpose processor configured to load a specific program and execute a specific function, and a dedicated processor specialized for a specific process. The processor may include a programmable logic device (PLD). The control device 5 may be either a system-on-a-chip (SoC) or a system-in-a-package (SiP) in which one or more processors work together. The control device 5 may include artificial intelligence (AI). The control device 5 may include a memory unit that may store various information, programs for operating each component of the display system 50, etc. The memory unit may be configured, for example, with a semiconductor memory. The memory unit may function as a work memory for the control device 5.

[0021] The display system 50 may include a camera that captures an image of the face of the driver 12. The control device 5 may detect the position of the eyes of the driver 12 as coordinates in three-dimensional space from the image captured by the camera. The position of the eyes of the driver 12 may be the interocular center (i.e., the midpoint of the line segment connecting both eyes). The display system 50 does not need to include a camera. For example, the display system 50 may acquire an image of the face of the driver 12 from a driver monitoring system, and detect the position of the eyes of the driver 12 based on the acquired image.

[0022] The display system 50 does not need to detect the position of the eyes of the driver 12. The display system 50 may determine a position within an eyebox as the position of the eyes of the driver 12. The eyebox is an area in real space where it is assumed that the eyes of the driver 12 may be present. The eyebox may be determined in advance, taking into consideration, for example, the physique and posture of the driver 12. The shape of the eyebox is arbitrary. The eyebox may be a planar area or a three-dimensional area. The position of the eyes of the driver 12 may be the center (center of gravity) of the eyebox.

[0023] The first imaging device 1 captures an image of the area behind the driver's seat side of the vehicle 9 and outputs the image data to the control device 5. The first imaging device 1 may be disposed at a position where a mirror-type driver's seat side door mirror is disposed, as shown in FIGS. 2 and 3 . The second imaging device 2 captures an image of the area behind the passenger's seat side of the vehicle 9 and outputs the image data to the control device 5. The second imaging device 2 may be disposed at a position where a mirror-type passenger's seat side door mirror is disposed, as shown in FIGS. 2 and 3 . The first imaging device 1 and the second imaging device 2 may each include a camera. The camera may include, for example, a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) image sensor.

[0024] The control device 5 may recognize objects (e.g., other vehicles, pedestrians, etc.) in the images captured by the imaging devices 1 and 2. The control device 5 may perform image processing such as gradation correction, color correction, and contour correction on the images captured by the imaging devices 1 and 2. The control device 5 may cut out an image of a range to be displayed on the display device 100 from the images captured by the imaging devices 1 and 2.

[0025] The first display device 3 projects the image captured by the first imaging device 1 as a virtual image V into the field of view of the driver 12. The second display device 4 projects the image captured by the second imaging device 2 as a real image R into the field of view of the driver 12. Within the field of view of the driver 12, the virtual image V may be formed further back than the first display device 3, and the real image R may be formed further forward than the second display device 4.

[0026] The display system 50 may be configured so that a distance S1 (hereinafter also referred to as a first distance) between the driver's 12's eyes and the virtual image V and a distance S2 (hereinafter also referred to as a second distance) between the driver's 12's eyes and the real image R are approximately equal. In this case, the driver 12 can more easily view the virtual image V and the real image R, thereby further improving driving safety. The first distance S1 may be a distance along the emission direction of the image light from the first display device 3. The second distance S2 may be a distance along the emission direction of the image light from the second display device 4.

[0027] The first distance S1 and the second distance S2 do not need to be exactly the same. The first distance S1 and the second distance S2 only need to match within a range in which the diopter difference (diopters) is equal to or less than a predetermined value. The predetermined value may be, for example, 0.2 or less. In this case, the human eye cannot perceive the difference between the first distance S1 and the second distance S2, so the driver 12 perceives the virtual image V and the real image R as being equidistant from the driver's 12's eyes. For example, if the driver 12 is gazing at the virtual image V and the first distance S1 is 650 mm, the driver 12 will perceive the virtual image V and the real image R as being equidistant if the second distance S2 is within a range that satisfies the following formula (1): 1 / (1 / 0.65+0.2)≦S2≦1 / (1 / 0.65−0.2)...(1). The unit of length in formula (1) is m, and the diopter difference is 0.2. From formula (1), when the first distance S1 is 0.65 m, the second distance S2 may be in the range of 0.57 m≦S2≦0.74 m.

[0028] When the distance between the driver's 12's eyes and the first display device 3 is a third distance S3 and the distance between the driver's 12's eyes and the second display device 4 is a fourth distance S4 (see FIG. 3 ), the control device 5 may control the first display device 3 and / or the second display device 4 so that the difference between the first distance S1 and the third distance S3 is equal to or greater than the difference between the second distance S2 and the fourth distance S4. In this case, the virtual image V and the real image R can be projected equidistantly from the driver's 12's eyes. As a result, the driver 12 can more easily view the virtual image V and the real image R, making it easier to recognize the conditions to the sides and rear of the vehicle 9. This ultimately improves driving safety. The third distance S3 may be a distance along the emission direction of image light from the first display device 3. The fourth distance S4 may be a distance along the emission direction of image light from the second display device 4.

[0029] The control device 5 may control the first display device 3 and / or the second display device 4 so that the second distance S2 is equal to or greater than the first distance S1.

[0030] The display system 50 may be configured to make the size of the virtual image V and the size of the real image R approximately the same. In this case, the driver 12 can easily view the virtual image V and the real image R, and can easily recognize the conditions on the sides and rear of the vehicle 9. As a result, driving safety can be improved. The size of the virtual image V may be the size of the virtual image V at the projection position (projection surface) of the virtual image V. The size of the real image R may be the size of the real image R at the projection position (projection surface) of the real image R.

[0031] The size of the virtual image V and the size of the real image R do not need to be exactly the same. Within the field of view of the driver 12, the ratio of the horizontal size of the real image R to the horizontal size of the virtual image V may be, for example, 0.9 to 1.1, or 0.95 to 1.05. Furthermore, within the field of view of the driver 12, the ratio of the vertical size of the real image R to the vertical size of the virtual image V may be, for example, 0.9 to 1.1, or 0.95 to 1.05.

[0032] The control device 5 may control the first display device 3 and / or the second display device 4 so that the magnification of the real image R for the image displayed on the display surface 6 a of the display panel 6 of the second display device 4 is equal to or greater than the magnification of the virtual image V for the image displayed on the display surface 6 a of the display panel 6 of the first display device 3. In this case, it becomes possible to make the size of the virtual image V and the size of the real image R visually recognized by the driver 12 approximately the same.

[0033] The control device 5 may control the first display device 3 and / or the second display device 4 so that the size of the real image R is equal to or larger than the size of the virtual image V.

[0034] Next, we will explain the configuration of the first display device 3 and the second display device 4. As shown in FIG. 1 , the first display device 3 and the second display device 4 each include a display panel 6, an optical system 7, and a drive unit 8.

[0035] As shown in Figures 4A and 4B, the display panel 6 has a display surface 6a and displays an image G on the display surface 6a. In other words, the display panel 6 emits image light of the image G from the display surface 6a. The display panel 6 may emit linearly polarized image light in the Z-axis direction (emission direction). The display panel 6 may emit linearly polarized image light having a polarization axis in a first direction. The linearly polarized light having a polarization axis in the first direction may be S-wave polarized light. The following describes a case where the display panel 6 emits S-wave polarized image light, but the present invention is not limited to this, and the display panel 6 may also emit P-wave polarized image light.

[0036] The display panel 6 may be a liquid crystal panel. The liquid crystal panel may be a known liquid crystal panel. The known liquid crystal panel may be, for example, an IPS (In-Plane Switching) type, an FFS (Fringe Field Switching) type, a VA (Vertical Alignment) type, an ECB (Electrically Controlled Birefringence) type, or the like.

[0037] The first display device 3 and the second display device 4 may each include an illuminator 13 that illuminates the display panel 6 in a planar manner. The illuminator 13 is also referred to as a backlight. The illuminator 13 may be an edge-lit backlight or a direct-lit backlight. An edge-lit backlight has one or more light sources arranged around the periphery of the display panel 6, and the light emitted from the light sources is guided by a light guide plate to the entire back surface of the display panel 6, where it is uniformly dispersed. A direct-lit backlight has multiple light sources arranged on the back side of the display panel 6, and irradiates the display panel 6 with light emitted from the multiple light sources. The light source of the illuminator 13 may be a cold cathode fluorescent lamp, a halogen lamp, a xenon lamp, or the like, or may be a light-emitting diode (LED), an organic light-emitting diode (OLED), a semiconductor laser (LD), or the like. If the light source of the illuminator 13 is an LD with excellent monochromaticity, the design of the optical system 7 (especially the design of optical components whose optical characteristics are wavelength-dependent) becomes easier.

[0038] The optical system 7 can project the image G displayed on the display panel 6 as a real image R or a virtual image V into the field of view of the driver 12. As shown in FIGS. 4A and 4B , the optical system 7 includes a first semi-transmitting mirror 14, a second semi-transmitting mirror 15, a third semi-transmitting mirror 16, a first retardation plate 17, and a second retardation plate 18. The second semi-transmitting mirror 15, the first retardation plate 17, the first semi-transmitting mirror 14, the second retardation plate 18, and the third semi-transmitting mirror 16 are arranged in this order in the emission direction of the image light from the display panel 6.

[0039] The first semi-transmitting mirror 14 is located away from the display surface 6a of the display panel 6 in the emission direction of the image light. The first semi-transmitting mirror 14 may transmit a portion (approximately 50%) of the incident light and reflect the remaining portion (approximately 50%). The first semi-transmitting mirror 14 has a reflective surface 14a facing the first retardation plate 17 and a reflective surface 14b facing the second retardation plate 18. In this embodiment, the first semi-transmitting mirror 14 is a plane mirror (plane half mirror) whose reflective surfaces 14a and 14b are parallel or approximately parallel to the display surface 6a.

[0040] The first semi-transparent mirror 14 may be configured to include, for example, a substrate and a semi-transparent layer located on the surface of the substrate. The substrate may have a transmittance of 100% or close to 100% for light in the visible light band. The substrate may be configured from, for example, inorganic glass, a resin material, or the like. The resin material may be, for example, an acrylic resin, a polycarbonate resin, or the like. The semi-transparent layer may be a metal thin film. The metal thin film may be configured from a metal material such as aluminum or chromium. The semi-transparent layer is not limited to a metal thin film and may be, for example, a dielectric multilayer film, or the like.

[0041] The first retardation plate 17 is located between the display panel 6 and the first semi-transmitting mirror 14. The second retardation plate 18 is located on the opposite side of the first semi-transmitting mirror 14 from the first retardation plate 17. The first retardation plate 17 and the second retardation plate 18 may be quarter-wave plates. The first retardation plate 17 and the second retardation plate 18 may be fixed to the first semi-transmitting mirror 14 by an optically transparent adhesive such as an optically clear adhesive (OCA). The adhesive may be a material with small retardation (phase difference).

[0042] The second semi-transmitting mirror 15 is located between the display panel 6 and the first retardation plate 17. The second semi-transmitting mirror 15 may transmit a portion of the incident light and reflect the remainder. The second semi-transmitting mirror 15 may transmit polarized light having a polarization axis in a first direction (S-wave polarization) and reflect polarized light having a polarization axis in a second direction orthogonal to the first direction (P-wave polarization). As shown in FIGS. 4A and 4B , the second semi-transmitting mirror 15 may be a concave mirror having a concave reflecting surface 15a that faces the reflecting surface 14a of the first semi-transmitting mirror 14 via the first retardation plate 17. At least a portion of the reflecting surface 15a of the second semi-transmitting mirror 15 may include a spherical, aspherical, or free-form surface shape.

[0043] The second semi-transparent mirror 15 may be configured to include a substrate and a plurality of thin metal wires (metal nanowire grid) located on the surface of the substrate. The substrate may have a transmittance of 100% or close to 100% for light in the visible light band. The substrate may be configured from, for example, a resin material, a glass material, or the like. The resin material may be, for example, an acrylic resin, a polycarbonate resin, or the like. The thin metal wires may be configured from a metal material, for example, aluminum, chromium, titanium oxide, or the like. The second semi-transparent mirror 15 can transmit polarized light oscillating in a direction perpendicular to the grid and can reflect polarized light oscillating in a direction parallel to the grid.

[0044] The third semi-transmitting mirror 16 is located on the opposite side of the first semi-transmitting mirror 14, the first retardation plate 17, and the second retardation plate 18 from the second semi-transmitting mirror 15. The third semi-transmitting mirror 16 may transmit a portion of the incident light and reflect the remainder. The third semi-transmitting mirror 16 may reflect polarized light having a polarization axis in a first direction (S-wave polarization) and transmit polarized light having a polarization axis in a second direction orthogonal to the first direction (P-wave polarization). As shown in FIGS. 4A and 4B , the third semi-transmitting mirror 16 may be a concave mirror having a concave reflecting surface 16a that faces the reflecting surface 14b of the first semi-transmitting mirror 14 via the second retardation plate 18. At least a portion of the reflecting surface 16a of the third semi-transmitting mirror 16 may include a spherical, aspherical, or free-form surface shape.

[0045] The third semi-transparent mirror 16 may also be configured to include a substrate and a plurality of thin metal wires (metal nanowire grid) located on the surface of the substrate.

[0046] The second and third semi-transparent mirrors 15 and 16 are not limited to concave mirrors. The second and third semi-transparent mirrors 15 and 16 may be configured as holographic optical elements. In this case, the optical functions of the second and third semi-transparent mirrors 15 and 16 can be realized by flat optical members. As a result, the thickness of the second and third semi-transparent mirrors 15 and 16 in the depth direction (Z-axis direction) can be reduced, and the optical system 7 can be made smaller in size in the depth direction.

[0047] The driver 8 adjusts the relative position between the focal point F on the display panel 6 side (object focal point) of the optical system 7 and the display panel 6. The driver 8 may be configured to be able to adjust the relative position between the display panel 6 and the optical system 7. The driver 8 may be configured to be able to adjust the relative positions of the optical members included in the optical system 7, in particular the relative positions of the first semi-transparent mirror 14, the second semi-transparent mirror 15, and the third semi-transparent mirror 16. The driver 8 may be configured to be able to adjust the focal lengths of the second semi-transparent mirror 15 and the third semi-transparent mirror 16.

[0048] The driving unit 8 may be configured, for example, by an electric slider, an electric cylinder, etc. The driving unit 8 may be configured so that the driver 12 can manually adjust the relative position between the object focus F of the optical system 7 and the display panel 6.

[0049] When moving the display panel 6, the drive unit 8 may move the illuminator 13 together with the display panel 6 so that the distance between the display panel 6 and the illuminator 13 is maintained substantially constant. In this case, the amount of light irradiated onto the display panel 6 can be maintained substantially constant, thereby reducing fluctuations in the amount of image light emitted from the display panel 6. Therefore, changes in the luminance of the virtual image V and real image R viewed by the driver 12 can be reduced.

[0050] The first display device 3 and the second display device 4 may be configured to be able to change the focal lengths of the second semi-transparent mirror 15 and the third semi-transparent mirror 16. The first display device 3 and the second display device 4 may, for example, include a deformation unit that can deform the second semi-transparent mirror 15 and the third semi-transparent mirror 16 (changing the curvature, shape, etc. of the reflecting surfaces 15 a, 16 a). The deformation unit can change the focal lengths of the second semi-transparent mirror 15 and the third semi-transparent mirror 16 by deforming the second semi-transparent mirror 15 and the third semi-transparent mirror 16. The deformation unit may be configured, for example, by an electric slider, an electric cylinder, etc. The deformation unit may constitute a part of the drive unit 8.

[0051] Next, a description will be given of the traveling path of the image light incident on the optical system 7. The image light incident on the optical system 7 travels along a path P1 or a path P2, as shown in Figures 4A and 4B.

[0052] The light traveling along path P1 will be described. The S-wave polarized image light (first linearly polarized light L1) emitted from the display panel 6 passes through the second semi-transparent mirror 15. The first linearly polarized light L1 passes through the first retardation plate 17 and is converted into first circularly polarized light C1. The first circularly polarized light C1 is incident on the first semi-transparent mirror 14. A portion (approximately 50%) of the first circularly polarized light C1 is reflected by the first semi-transparent mirror 14 and converted into second circularly polarized light C2. The second circularly polarized light C2 passes through the first retardation plate 17 and is converted into second linearly polarized light L2, the polarization axis of which is orthogonal to the polarization axis of the first linearly polarized light L1 (i.e., P-wave polarized light). The second linearly polarized light L2 is reflected by the second semi-transparent mirror 15 and is converted into third linearly polarized light L3, the polarization axis of which is orthogonal to the polarization axis of the first linearly polarized light L1 (i.e., P-wave polarized light). The third linearly polarized light L3 passes through the first retardation plate 17 and is converted into third circularly polarized light C3. The third circularly polarized light C3 is incident on the first semi-transparent mirror 14. A portion (approximately 50%) of the third circularly polarized light C3 passes through the first semi-transparent mirror 14. The third circularly polarized light C3 that passed through the first semi-transparent mirror 14 passes through the second retardation plate 18 and is converted into fourth linearly polarized light L4 whose polarization axis is orthogonal to the polarization axis of the first linearly polarized light L1 (i.e., P-polarized light). The fourth linearly polarized light L4 passes through the third semi-transparent mirror 16 and is emitted to the outside.

[0053] The light traveling along path P2 will now be described. The remainder (approximately 50%) of the first circularly polarized light C1 incident on the first semi-transparent mirror 14 is transmitted through the first semi-transparent mirror 14. The first circularly polarized light C1 transmitted through the first semi-transparent mirror 14 is transmitted through the second retardation plate 18 and converted into fifth linearly polarized light L5 whose polarization axis is parallel to the polarization axis of the first linearly polarized light L1 (i.e., S-wave polarization). The fifth linearly polarized light L5 is reflected by the third semi-transparent mirror 16 and converted into sixth linearly polarized light L6 whose polarization axis is parallel to the polarization axis of the first linearly polarized light L1 (i.e., S-wave polarization). The sixth linearly polarized light L6 is transmitted through the second retardation plate 18 and converted into fourth circularly polarized light C4. The fourth circularly polarized light C4 is incident on the first semi-transparent mirror 14. A portion (approximately 50%) of the fourth circularly polarized light C4 is reflected by the first semi-transparent mirror 14 and converted into fifth circularly polarized light C5. The fifth circularly polarized light C5 passes through the second retardation plate 18 and is converted into seventh linearly polarized light L7 whose polarization axis is orthogonal to the polarization axis of the first linearly polarized light L1 (i.e., P-polarized light). The seventh linearly polarized light L7 passes through the third semi-transparent mirror 16 and is emitted to the outside.

[0054] The image light incident on the optical system 7 travels along path P1 or path P2 and is emitted to the outside. As a result, the amount of image light emitted via the optical system 7 is approximately 50% of the amount of image light incident on the optical system 7. Since the optical system 7 has a relatively high light utilization efficiency, the first display device 3 and the second display device 4 can improve the brightness of the virtual image V or real image R visually recognized by the driver 12.

[0055] (First Display Device 3) The control of the first display device 3 by the control device 5 will be described. The control device 5 controls the display panel 6 to display an image based on the image captured by the first imaging device 1. As shown in FIG. 4A , the control device 5 controls at least one of the display panel 6 and the optical system 7 so that the display panel 6 is positioned closer (to the optical system 7) than the object focus F in the optical system 7. In other words, the control device 5 controls at least one of the display panel 6 and the optical system 7 so that the optical path length of the image light from the display panel 6 via the first semi-transparent mirror 14 to the second semi-transparent mirror 15 or the third semi-transparent mirror 16 is shorter than the focal length of the second semi-transparent mirror 15 or the third semi-transparent mirror 16. This allows the first display device 3 to project the image G displayed on the display panel 6 as a virtual image V located behind the first display device 3 within the field of view of the driver 12 (see FIG. 1 ). The driver 8 may control the optical system 7 so that the focal length of the second semi-transmitting mirror 15 and the focal length of the third semi-transmitting mirror 16 are approximately equal. The driver 8 may control at least one of the display panel 6 and the optical system 7 so that the distance between the first semi-transmitting mirror 14 and the second semi-transmitting mirror 15 and the distance between the first semi-transmitting mirror 14 and the third semi-transmitting mirror 16 are approximately equal, and the optical path length between the display panel 6 and the second semi-transmitting mirror 15 or the third semi-transmitting mirror 16 (the distance between the display panel 6 and the third semi-transmitting mirror 16) is shorter than the focal lengths of the second semi-transmitting mirror 15 and the third semi-transmitting mirror 16. In this case, the virtual image formed by the image light traveling along the path P1 and the virtual image formed by the image light traveling along the path P2 substantially coincide with each other, thereby improving the display quality of the virtual image V viewed by the driver 12. The driving unit 8 may set the ratio of the focal length of the third semi-transparent mirror 16 to the focal length of the second semi-transparent mirror 15 to be 0.9 or more and 1.1 or less, or 0.95 or more and 1.05 or less. The driving unit 8 may set the ratio of the distance between the first semi-transparent mirror 14 and the third semi-transparent mirror 16 to the distance between the first semi-transparent mirror 14 and the second semi-transparent mirror 15 to be 0.9 or more and 1.1 or less, or 0.95 or more and 1.05 or less.

[0056] (Second Display Device 4) The control of the second display device 4 by the control device 5 will be described. The control device 5 controls the display panel 6 to display an image based on the image captured by the second imaging device 2. As shown in FIG. 4B , the control device 5 controls at least one of the display panel 6 and the optical system 7 so that the display panel 6 is located farther from the object focus F in the optical system 7 (from the optical system 7). In other words, the control device 5 controls at least one of the display panel 6 and the optical system 7 so that the optical path length of the image light from the display panel 6, via the first semi-transparent mirror 14, to the second semi-transparent mirror 15 or the third semi-transparent mirror 16 is longer than the focal length of the second semi-transparent mirror 15 or the third semi-transparent mirror 16. This allows the second display device 4 to project the image G displayed on the display panel 6 as a real image R located in front of the second display device 4 within the field of view of the driver 12 (see FIG. 1 ). The driver 8 may control the optical system 7 so that the focal length of the second semi-transmitting mirror 15 and the focal length of the third semi-transmitting mirror 16 are approximately equal. The driver 8 may control at least one of the display panel 6 and the optical system 7 so that the distance between the first semi-transmitting mirror 14 and the second semi-transmitting mirror 15 and the distance between the first semi-transmitting mirror 14 and the third semi-transmitting mirror 16 are approximately equal, and the optical path length between the display panel 6 and the second semi-transmitting mirror 15 or the third semi-transmitting mirror 16 (the distance between the display panel 6 and the third semi-transmitting mirror 16) is longer than the focal lengths of the second semi-transmitting mirror 15 and the third semi-transmitting mirror 16. In this case, the real image formed by the image light traveling along the path P1 and the real image formed by the image light traveling along the path P2 substantially coincide with each other, thereby improving the display quality of the real image R viewed by the driver 12. The driving unit 8 may set the ratio of the focal length of the third semi-transparent mirror 16 to the focal length of the second semi-transparent mirror 15 to be 0.9 or more and 1.1 or less, or 0.95 or more and 1.05 or less. The driving unit 8 may set the ratio of the distance between the first semi-transparent mirror 14 and the third semi-transparent mirror 16 to the distance between the first semi-transparent mirror 14 and the second semi-transparent mirror 15 to be 0.9 or more and 1.1 or less, or 0.95 or more and 1.05 or less.

[0057] The optical system 7 is a uniaxial (on-axis) optical system in which the optical axis of the incident light and the optical axis of the outgoing light are substantially aligned. Therefore, the display system 50 can reduce distortion and brightness unevenness of the virtual image V and real image R visually recognized by the driver 12. Furthermore, the design of the optical system 7 is simplified, and the focus, focal length, and other aspects of the optical system 7 can be easily controlled.

[0058] The control device 5 may perform local dimming control of the illuminator 13 in accordance with the image G displayed on the display panel 6. In this case, it becomes possible to project a clear virtual image V and real image R with improved contrast into the field of view of the driver 12.

[0059] Next, an example of the optical design of the first display device 3 and the second display device 4 will be described. In the following description, it is assumed that the first display device 3 projects a virtual image V at a distance of approximately 650 mm from the eyes of the driver 12, and the second display device 4 projects a real image R at a distance of approximately 650 mm from the eyes of the driver 12. It is assumed that the first display device 3 is disposed on the A-pillar 9a on the driver's seat side, and the second display device 4 is disposed on the A-pillar 9b on the passenger's seat side. It is assumed that the distance between the eyes of the driver 12 and the A-pillar 9a on the driver's seat side is 400 mm, and the distance between the eyes of the driver 12 and the A-pillar 9b on the passenger's seat side is 1000 mm.

[0060] The optical design of the first display device 3 will now be described. As shown in Fig. 5, the distance between the eyes of the driver 12 and the first semi-transparent mirror 14 is A (mm), the distance between the first semi-transparent mirror 14 and the second semi-transparent mirror 15 and the distance between the first semi-transparent mirror 14 and the third semi-transparent mirror 16 is B (mm), and the distance between the display panel 6 and the second semi-transparent mirror 15 is C (mm). Furthermore, the focal length of the second semi-transparent mirror 15 and the third semi-transparent mirror 16 is f (mm). Table 1 shows an example of the optical design of the first display device 3.

[0061]

[0062] The optical path length a (mm) between the display panel 6 and the reflecting surfaces 15a, 16a that reflect the image light emitted from the display panel 6 is expressed as a = 2 × B + C. In the example of Table 1, the optical path length a is 99 mm. Since the optical path length a (mm) is smaller than the focal length f (mm), the driver 12 sees the virtual image V. The distance between the second semi-transparent mirror 15 and the virtual image V is expressed as b Ｖ (mm), the distance b Ｖ is expressed by the following formula (1): Ｖ =1 / (1 / a-1 / f)...(1)

[0063] In the example of Table 1, the distance between the eyes of the driver 12 and the second semi-transparent mirror 15 (i.e., A+B) is 447 mm, whereas the distance between the eyes of the driver 12 and the virtual image V (i.e., A+B+b Ｖ ) is 649 mm. Therefore, the driver 12 visually recognizes the virtual image V at a distance farther than the second semi-transparent mirror 15. The magnification m of the virtual image V relative to the image G displayed on the display surface 6a is Ｖ is m Ｖ = b Ｖ / a, and in the example of Table 1, the magnification m Ｖ becomes 2.0.

[0064] The optical design of the second display device 4 will now be described. Table 2 shows an example of the optical design of the second display device 4. The definitions of the distances A, B, C and the focal length f are as described above.

[0065]

[0066] The optical path length a (mm) between the display panel 6 and the reflecting surfaces 15a, 16a that reflect the image light emitted from the display panel 6 is expressed as a = 2 x B + C. In the example of Table 2, the optical path length a is 175.4 mm. Since the optical path length a (mm) is greater than the focal length f (mm), the driver 12 sees the real image R. Let b be the distance between the second semi-transparent mirror 15 and the real image R. Ｒ (mm), the distance b Ｒ is expressed by the following formula (1): Ｒ =1 / (1 / f-1 / a)...(1)

[0067] In the example of Table 2, the distance between the eyes of the driver 12 and the second semi-transparent mirror 15 (i.e., A+B) is 1085.2 mm, whereas the distance between the eyes of the driver 12 and the real image R (i.e., A+B-b Ｒ ) is 734.7 mm. Therefore, the driver 12 visually recognizes the real image R closer than the second semi-transparent mirror 15 and the third semi-transparent mirror 16. The magnification m of the real image R relative to the image G displayed on the display surface 6a is m Ｒ = b Ｒ / a, and in the example of Table 1, the magnification m Ｒ becomes 2.0.

[0068] As described above, the display system 50 can project the virtual image V and the real image R at equal distances from the eyes of the driver 12 within a range where the diopter difference is 0.2 or less. Ｖ and the magnification m of the real image R Ｒ Therefore, by displaying an image G of the same size on the display panels 6 of the first display device 3 and the second display device 4, the size of the virtual image V and the size of the real image R in the field of view of the driver 12 can be made to substantially match.

[0069] Next, a description will be given of another example of the optical system in the display system 50. The first display device 3 and the second display device 4 may have an optical system 19 shown in Figures 6A and 6B instead of the optical system 7 shown in Figures 4A and 4B.

[0070] The optical system 19 includes a first semi-transparent mirror 20, a second semi-transparent mirror 21, a first retardation plate 22, and a second retardation plate 23. As shown in Figures 6A and 6B, the first retardation plate 22, the first semi-transparent mirror 20, the second retardation plate 23, and the second semi-transparent mirror 21 are arranged in this order in the Z-axis direction (the direction in which image light is emitted from the display panel 6).

[0071] The first semi-transmitting mirror 20 is located away from the display surface 6a of the display panel 6 in the direction in which the image light is emitted. The first semi-transmitting mirror 20 may transmit a portion (approximately 50%) of the incident light and reflect the remaining portion (approximately 50%). As shown in FIG. 5 , the first semi-transmitting mirror 20 may be a plane mirror having a reflective surface 20a facing the first retardation plate 22 and a reflective surface 20b facing the second retardation plate 23. The first semi-transmitting mirror 20 is also referred to as a plane half mirror. The reflective surfaces 20a and 20b may be parallel or approximately parallel to the display surface 6a.

[0072] The first semi-transparent mirror 20 may be configured to include, for example, a substrate and a semi-transparent layer located on the surface of the substrate. The substrate may have a transmittance of 100% or close to 100% for light in the visible light band. The substrate may be configured from, for example, inorganic glass, a resin material, or the like. The resin material may be, for example, an acrylic resin, a polycarbonate resin, or the like. The semi-transparent layer may be a metal thin film. The metal thin film may be configured from a metal material such as aluminum, chromium, or the like. The semi-transparent layer is not limited to a metal thin film and may be, for example, a dielectric multilayer film, or the like.

[0073] The first retardation plate 22 is located between the display panel 6 and the first semi-transmitting mirror 20. The second retardation plate 23 is located on the opposite side of the first semi-transmitting mirror 20 from the first retardation plate 22. The first retardation plate 22 and the second retardation plate 23 may be quarter-wave plates. The first retardation plate 22 and the second retardation plate 23 may be fixed to the first semi-transmitting mirror 20 by an optically transparent adhesive such as an optically clear adhesive (OCA). The adhesive may be a material with small retardation (phase difference).

[0074] The second semi-transmitting mirror 21 is positioned away from the second retardation plate 23 in the Z-axis direction (the direction in which image light is emitted from the display panel 6). The second semi-transmitting mirror 21 may transmit a portion of the incident light and reflect the remainder. The second semi-transmitting mirror 21 may transmit polarized light having a polarization axis in a first direction (S-wave polarization) and reflect polarized light having a polarization axis in a second direction perpendicular to the first direction (P-wave polarization). As shown in FIGS. 6A and 6B , the second semi-transmitting mirror 21 may be a concave mirror having a concave reflecting surface 21a facing the reflecting surface 20b of the first semi-transmitting mirror 20 via the second retardation plate 23. At least a portion of the reflecting surface 21a of the second semi-transmitting mirror 21 may include a spherical, aspherical, or free-form surface shape.

[0075] The second semi-transparent mirror 21 may be configured to include a substrate and a plurality of thin metal wires (metal nanowire grid) located on the surface of the substrate. The substrate may have a transmittance of 100% or close to 100% for light in the visible light band. The substrate may be configured from, for example, a resin material, a glass material, or the like. The resin material may be, for example, an acrylic resin, a polycarbonate resin, or the like. The thin metal wires may be configured from a metal material, for example, aluminum, chromium, titanium oxide, or the like. The second semi-transparent mirror 21 can transmit polarized light oscillating in a direction perpendicular to the grid and can reflect polarized light oscillating in a direction parallel to the grid.

[0076] The travel path of the image light incident on the optical system 19 will be described. The display panel 6 emits S-wave polarized image light (first linearly polarized light L1). The first linearly polarized image light L1 emitted from the display panel 6 passes through the first retardation plate 22 and is converted into first circularly polarized light C1. A portion (approximately 50%) of the first circularly polarized light C1 transmitted through the first retardation plate 22 passes through the first semi-transparent mirror 20. The first circularly polarized light C1 transmitted through the first semi-transparent mirror 20 passes through the second retardation plate 23 and is converted into second linearly polarized light L2 whose polarization axis is orthogonal to the polarization axis of the first linearly polarized light L1 (i.e., P-wave polarized light). The second linearly polarized light L2 enters the second semi-transparent mirror 21. The second linearly polarized light L2 incident on the second semi-transparent mirror 21 is reflected by the second semi-transparent mirror 21 and converted into third linearly polarized light L3. The light of the third linearly polarized light L3 passes through the second retardation plate 23 and is converted into light of the second circularly polarized light C2. A portion (approximately 50%) of the light of the second circularly polarized light C2 that passed through the second retardation plate 23 is reflected by the first semi-transparent mirror 20 and converted into light of the third circularly polarized light C3. The light of the third circularly polarized light C3 passes through the second retardation plate 23 and is converted into light of the fourth linearly polarized light L4 whose polarization axis is parallel to the polarization axis of the first linearly polarized light L1 (i.e., S-wave polarization). The light of the fourth linearly polarized light L4 passes through the second semi-transparent mirror 21 and is emitted to the outside. The amount of image light that passes through the optical system 19 is approximately 25% of the amount of image light that entered the optical system 19.

[0077] (First Display Device 3) The control of the first display device 3 by the control device 5 will be described. The control device 5 controls the display panel 6 to display an image based on the image captured by the first imaging device 1. As shown in FIG. 6A , the control device 5 controls at least one of the display panel 6 and the optical system 19 so that the display panel 6 is positioned closer (to the optical system 19) than the object focus F in the optical system 19. In other words, the control device 5 controls at least one of the display panel 6 and the optical system 19 so that the optical path length of the image light from the display panel 6 via the first semi-transparent mirror 20 to the second semi-transparent mirror 21 is shorter than the focal length of the second semi-transparent mirror 21. This allows the first display device 3 to project the image G displayed on the display panel 6 as a virtual image V located behind the first display device 3 within the field of view of the driver 12 (see FIG. 3 ). The driver 8 may control at least one of the display panel 6 and the optical system 19 so that the distance between the first semi-transparent mirror 20 and the second semi-transparent mirror 21 is shorter than the focal length of the optical system 19 on the display panel 6 side. This makes it possible to make the optical path length of the image light from the display panel 6, via the first semi-transparent mirror 20, to the second semi-transparent mirror 21 shorter than the focal length of the second semi-transparent mirror 21.

[0078] (Second Display Device 4) The control of the second display device 4 by the control device 5 will be described. The control device 5 controls the display panel 6 to display an image based on the image captured by the second imaging device 2. The control device 5 controls at least one of the display panel 6 and the optical system 19 so that the display panel 6 is located farther from the object focus F of the optical system 19 (from the optical system 19), as shown in FIG. 6B . In other words, the control device 5 controls at least one of the display panel 6 and the optical system 19 so that the optical path length of the image light from the display panel 6 to the second semi-transparent mirror 21 via the first semi-transparent mirror 20 is longer than the focal length of the second semi-transparent mirror 21. This allows the first display device 3 to project the image G displayed on the display panel 6 as a real image R located in front of the second display device 4 within the field of view of the driver 12 (see FIG. 3 ). The driver 8 may control at least one of the display panel 6 and the optical system 19 so that the distance between the first semi-transparent mirror 20 and the second semi-transparent mirror 21 is greater than the focal length of the optical system 19 on the display panel 6 side. This makes it possible to make the optical path length of the image light from the display panel 6, via the first semi-transparent mirror 20, to the second semi-transparent mirror 21 greater than the focal length of the second semi-transparent mirror 21.

[0079] When the first display device 3 and the second display device 4 have the optical system 19, the display system 50 can project the image captured by the first imaging device 1 as a virtual image V formed behind the first display device 3 into the field of view of the driver 12, and can project the image captured by the second imaging device 2 as a real image R formed in front of the second display device 4 into the field of view of the driver 12. Therefore, the difference between the distance between the eyes of the driver 12 and the virtual image V and the distance between the eyes of the driver 12 and the real image R can be reduced. As a result, the driver 12 can easily view the virtual image V and the real image R, thereby improving driving safety.

[0080] In the display system 50, when the first display device 3 and the second display device 4 have the optical system 19, the first distance S1 and the second distance S2 can be made substantially equal to each other. Therefore, the difference between the distance between the driver's 12's eyes and the virtual image V and the distance between the driver's 12's eyes and the real image R can be further reduced. As a result, the driver 12 can more easily view the virtual image V and the real image R, thereby further improving driving safety. Furthermore, in the display system 50, when the first display device 3 and the second display device 4 have the optical system 19, the size of the virtual image V and the size of the real image R can be made substantially equal to each other. Therefore, the driver 12 can more easily view the virtual image V and the real image R, and can more easily recognize the situations to the sides and rear of the vehicle 9. As a result, driving safety can be improved.

[0081] Next, a description will be given of yet another example of the optical system in the display system 50. The first display device 3 and the second display device 4 may have the optical system 24 shown in Figures 7A and 7B instead of the optical systems 7 and 19 shown in Figures 4A, 4B, 6A, and 6B.

[0082] 7A and 7B , the second semi-transmitting mirror 26, the first retardation plate 27, and the second retardation plate 28 are arranged in this order in the Z-axis direction (the direction in which image light is emitted from the display panel 6). The first semi-transmitting mirror 25, the first retardation plate 27, and the second retardation plate 28 have the same configurations as the first semi-transmitting mirror 20, the first retardation plate 22, and the second retardation plate 23 of the optical system 19, respectively, and therefore will not be described here.

[0083] The second semi-transmitting mirror 26 is located between the display panel 6 and the first retardation plate 27. The second semi-transmitting mirror 26 may transmit a portion of the incident light and reflect the remainder. The second semi-transmitting mirror 26 may transmit polarized light having a polarization axis in a first direction (S-wave polarization) and reflect polarized light having a polarization axis in a second direction orthogonal to the first direction (P-wave polarization). As shown in FIG. 7 , the second semi-transmitting mirror 26 may be a concave mirror having a concave reflecting surface 26a that faces the reflecting surface 25a of the first semi-transmitting mirror 25 via the first retardation plate 27. At least a portion of the reflecting surface 26a of the second semi-transmitting mirror 26 may include a spherical, aspherical, or free-form surface shape.

[0084] The second semi-transparent mirror 26 may also be configured to include a substrate and a plurality of thin metal wires (metal nanowire grid) located on the surface of the substrate.

[0085] The travel path of the image light incident on the optical system 24 will be described. The S-wave polarized image light (first linearly polarized light L1) emitted from the display panel 6 passes through the second semi-transparent mirror 26. The first linearly polarized light L1 that passed through the second semi-transparent mirror 26 passes through the first retardation plate 27 and is converted into first circularly polarized light C1. A portion (approximately 50%) of the first circularly polarized light C1 that passed through the first retardation plate 27 passes through the first semi-transparent mirror 25, and the remaining portion (approximately 50%) of the first circularly polarized light C1 that passed through the first retardation plate 27 is reflected by the first semi-transparent mirror 25 and converted into fourth circularly polarized light C4. The fourth circularly polarized light C4 passes through the first retardation plate 27 and is converted into fifth linearly polarized light L5 whose polarization axis is orthogonal to the polarization axis of the first linearly polarized light L1 (i.e., P-wave polarized light). The fifth linearly polarized light L5 is incident on the second semi-transparent mirror 26. The light of the fifth linearly polarized light L5 incident on the second semi-transparent mirror 26 is reflected by the second semi-transparent mirror 26 and converted into light of the sixth linearly polarized light L6. A portion (approximately 50%) of the sixth linearly polarized light L6 passes through the first retardation plate 27, the first semi-transparent mirror 25, and the second retardation plate 28, and is emitted to the outside. The amount of image light emitted via the optical system 24 is approximately 25% of the amount of image light incident on the optical system 24.

[0086] (First Display Device 3) The control of the first display device 3 by the control device 5 will be described. The control device 5 controls the display panel 6 to display an image based on the image captured by the first imaging device 1. As shown in FIG. 7A , the control device 5 controls at least one of the display panel 6 and the optical system 24 so that the display panel 6 is positioned closer (to the optical system 24) than the object focus F in the optical system 24. In other words, the control device 5 controls at least one of the display panel 6 and the optical system 24 so that the optical path length of the image light from the display panel 6 via the first semi-transparent mirror 25 to the second semi-transparent mirror 26 is shorter than the focal length of the second semi-transparent mirror 26. This allows the first display device 3 to project the image G displayed on the display panel 6 as a virtual image V located behind the first display device 3 within the field of view of the driver 12 (see FIG. 3 ). The driver 8 may control at least one of the display panel 6 and the optical system 24 so that the sum of twice the distance between the first semi-transparent mirror 25 and the second semi-transparent mirror 26 and the distance between the display panel 6 and the second semi-transparent mirror 26 is smaller than the focal length of the optical system 24 on the display panel 6 side. This makes it possible to make the optical path length of the image light from the display panel 6, via the first semi-transparent mirror 20, to the second semi-transparent mirror 26 shorter than the focal length of the second semi-transparent mirror 26.

[0087] (Second Display Device 4) The control of the second display device 4 by the control device 5 will be described. The control device 5 controls the display panel 6 to display an image based on the image captured by the second imaging device 2. The control device 5 controls at least one of the display panel 6 and the optical system 24 so that the display panel 6 is located farther from the object focus F of the optical system 24 (from the optical system 24), as shown in FIG. 7B . In other words, the control device 5 controls at least one of the display panel 6 and the optical system 24 so that the optical path length of the image light from the display panel 6 to the second semi-transparent mirror 26 via the first semi-transparent mirror 25 is longer than the focal length of the second semi-transparent mirror 26. This allows the first display device 3 to project the image G displayed on the display panel 6 as a real image R located in front of the second display device 4 within the field of view of the driver 12 (see FIG. 3 ). The driver 8 may control at least one of the display panel 6 and the optical system 24 so that the sum of twice the distance between the first semi-transparent mirror 25 and the second semi-transparent mirror 26 and the distance between the display panel 6 and the second semi-transparent mirror 26 is greater than the focal length of the optical system 24 on the display panel 6 side. This makes it possible to make the optical path length of the image light from the display panel 6, via the first semi-transparent mirror 20, to the second semi-transparent mirror 26 greater than the focal length of the second semi-transparent mirror 26.

[0088] When the first display device 3 and the second display device 4 have the optical system 24, the display system 50 can project the image captured by the first imaging device 1 as a virtual image V formed behind the first display device 3 into the field of view of the driver 12, and can project the image captured by the second imaging device 2 as a real image R formed in front of the second display device 4 into the field of view of the driver 12. Therefore, the difference between the distance between the eyes of the driver 12 and the virtual image V and the distance between the eyes of the driver 12 and the real image R can be reduced. As a result, the driver 12 can easily view the virtual image V and the real image R, thereby improving driving safety.

[0089] In the display system 50, when the first display device 3 and the second display device 4 have the optical system 24, the first distance S1 and the second distance S2 can be made substantially equal to each other. Therefore, the difference between the distance between the driver's 12's eyes and the virtual image V and the distance between the driver's 12's eyes and the real image R can be further reduced. As a result, the driver 12 can more easily view the virtual image V and the real image R, thereby further improving driving safety. Furthermore, in the display system 50, when the first display device 3 and the second display device 4 have the optical system 24, the size of the virtual image V and the size of the real image R can be made substantially equal to each other. Therefore, the driver 12 can more easily view the virtual image V and the real image R, and can more easily recognize the situations to the sides and rear of the vehicle 9. As a result, driving safety can be improved.

[0090] In display system 50, both first display device 3 and second display device 4 do not need to have the same optical system. In display system 50, first display device 3 may have any of optical system 7, optical system 19, and optical system 24, and second display device 4 may have any of optical system 7, optical system 19, and optical system 24.

[0091] The display panel 6 may display a mixed image including a left-eye image and a right-eye image having parallax with respect to each other, and may emit image light of the mixed image. The first display device 3 and the second display device 4 may be located in the optical path of the image light emitted from the display panel 6 and may include optical elements that define the respective light ray directions of the image light for the left eye and the image light for the right eye. The optical elements may be configured to cause at least a portion of the image light for the left eye to reach the left eye of the driver 12, and at least a portion of the image light for the right eye to reach the right eye of the driver 12. In this case, the first display device 3 and the second display device 4 can allow the driver 12 to view a three-dimensional virtual image V and a three-dimensional real image R.

[0092] The optical element may be a parallax barrier or a lenticular lens. The parallax barrier may be formed of a liquid crystal panel. The optical element may be located before or after the optical systems 7, 19, and 24 in the direction in which the image light from the display panel 6 is emitted.

[0093] Other examples of the display system 50 will be described below. The display system 50 may be configured such that both the first display device 3 and the second display device 4 project virtual images into the field of view of the driver 12. As shown in FIG. 8 , the first display device 3 may be configured to project an image captured by the first imaging device 1 into the field of view of the driver 12 as a first virtual image V1 formed on the back side of the first display device 3. As shown in FIG. 8 , the second display device 4 may be configured to project an image captured by the second imaging device 2 into the field of view of the driver 12 as a second virtual image V2 formed on the back side of the second display device 4. The projection of the first virtual image V1 by the first display device 3 and the projection of the second virtual image V2 by the second display device 4 are the same as the projection of the virtual image V by the first display device 3 (see FIGS. 4A , 6A , and 7A ), and therefore will not be described here.

[0094] When the distance between the driver's 12's eyes and the first virtual image V1 is a first distance S5, the distance between the driver's 12's eyes and the second virtual image V2 is a second distance S6, the distance between the driver's 12's eyes and the first display device 3 is a third distance S7, and the distance between the driver's 12's eyes and the second display device 4 is a fourth distance S8 (see FIG. 8 ), the control device 5 may control the first display device 3 and / or the second display device 4 so that the difference between the first distance S5 and the third distance S7 is equal to or greater than the difference between the second distance S6 and the fourth distance S8. In this case, the first virtual image V1 and the second virtual image V2 can be projected equidistantly from the driver's 12's eyes. As a result, the driver 12 can more easily view the first virtual image V1 and the second virtual image V2, making it easier for him or her to recognize the conditions to the sides and rear of the vehicle 9. This ultimately improves driving safety. The first distance S5 and the third distance S7 may be distances along the emission direction of the image light from the first display device 3. The second distance S6 and the fourth distance S8 may be distances along the emission direction of the image light from the second display device 4.

[0095] The control device 5 may be configured such that the first distance S5 and the second distance S6 of the first display device 3 and / or the second display device 4 are substantially equal to each other. In this case, the driver 12 can easily view the first virtual image V1 and the second virtual image V2, and can easily recognize the situations to the sides and rear of the vehicle 9. As a result, driving safety can be improved.

[0096] The first distance S5 and the second distance S6 may be the same as long as the diopter difference is equal to or less than a predetermined value. The predetermined value may be equal to or less than 0.2. In this case, the driver 12 can more easily view the first virtual image V1 and the second virtual image V2, thereby further improving driving safety. The first distance S5 may be a distance along the emission direction of the image light from the first display device 3. The second distance S6 may be a distance along the emission direction of the image light from the second display device 4.

[0097] The control device 5 may be configured so that the first display device 3 and / or the second display device 4 make the size of the first virtual image V1 and the size of the second virtual image V2 approximately the same. In this case, the driver 12 can easily view the first virtual image V1 and the second virtual image V2, and can easily recognize the situations to the sides and rear of the vehicle 9. As a result, driving safety can be improved.

[0098] The size of the first virtual image V1 and the size of the second virtual image V2 do not need to be exactly the same. Within the field of view of the driver 12, the ratio of the horizontal size of the second virtual image V2 to the horizontal size of the first virtual image V1 may be, for example, 0.9 to 1.1, or 0.95 to 1.05. Furthermore, within the field of view of the driver 12, the ratio of the vertical size of the second virtual image V2 to the vertical size of the first virtual image V1 may be, for example, 0.9 to 1.1, or 0.95 to 1.05.

[0099] Another example of the display system 50 will be described. The display system 50 may be configured such that both the first display device 3 and the second display device 4 project real images into the field of view of the driver 12. As shown in FIG. 9 , the first display device 3 may be configured to project an image captured by the first imaging device 1 as a first real image R1 formed in front of the first display device 3 into the field of view of the driver 12. As shown in FIG. 9 , the second display device 4 may be configured to project an image captured by the second imaging device 2 as a second real image R2 formed in front of the second display device 4 into the field of view of the driver 12. The projection of the first real image R1 by the first display device 3 and the projection of the second real image R2 by the second display device 4 are the same as the projection of the real image R by the second display device 4 (see FIGS. 4B, 6B, and 7B), and therefore will not be described here.

[0100] When the distance between the driver's 12's eyes and the first real image R1 is a first distance S9 and the distance between the driver's 12's eyes and the second real image R2 is a second distance S10, the control device 5 may be configured so that the first display device 3 and / or the second display device 4 substantially coincide with the first distance S9 and the second distance S10. The first distance S9 may be a distance along the emission direction of image light from the first display device 3. The second distance S10 may be a distance along the emission direction of image light from the second display device 4. In this case, the first real image R1 reflecting the side rear of the driver's seat and the second real image R2 reflecting the side rear of the passenger's seat can be projected substantially equidistant from the driver's 12's eyes. As a result, the driver 12 can easily check the sides and rear of the vehicle 9, thereby improving driving safety.

[0101] The first distance S9 and the second distance S10 may be the same as long as the diopter difference is equal to or less than a predetermined value, which may be equal to or less than 0.2. In this case, the driver 12 can more easily view the first real image R1 and the second real image R2, thereby further improving driving safety.

[0102] The control device 5 may be configured such that the first display device 3 and / or the second display device 4 make the size of the first real image R1 and the size of the second real image R2 approximately the same. In this case, the driver 12 can easily view the first real image R1 and the second real image R2 and can easily recognize the situations on the sides and rear of the vehicle 9. This can ultimately improve driving safety.

[0103] The size of the first real image R1 and the size of the second real image R2 do not need to be exactly the same. Within the field of view of the driver 12, the ratio of the horizontal size of the second real image R2 to the horizontal size of the first real image R1 may be, for example, 0.9 to 1.1, or 0.95 to 1.05. Also, within the field of view of the driver 12, the ratio of the vertical size of the second real image R2 to the vertical size of the first real image R1 may be, for example, 0.9 to 1.1, or 0.95 to 1.05.

[0104] Other examples of the display device 30 will be described below. The display device 30 may be configured such that the first display device 3 projects an image of the area behind the driver's seat as a first image into the field of view of the driver 12, and the second display device 4 projects an image of the area behind the passenger seat as a second image into the field of view of the driver 12. The first image may be a virtual image or a real image. The second image may be a virtual image or a real image. The projection of the first image by the first display device 3 and the projection of the second image by the second display device 4 are the same as the projection of the virtual image V by the first display device 3 (see FIGS. 4A, 6A, and 7A) or the projection of the real image R by the second display device 4 (see FIGS. 4B, 6B, and 7B), and therefore will not be described here.

[0105] The distance between the driver's 12's eyes and the first image is defined as a first distance S11, the distance between the driver's 12's eyes and the second image is defined as a second distance S12, the distance between the driver's 12's eyes and the first display device 3 is defined as a third distance S13, and the distance between the driver's 12's eyes and the second display device 4 is defined as a fourth distance S14. The display device 30 may be configured such that the difference between the first distance S11 and the third distance S13 is equal to or greater than the difference between the second distance S12 and the fourth distance S14. In this case, the first image and the second image can be projected equidistantly from the driver's 12's eyes. As a result, the driver 12 can easily view the first image and the second image, making it easier to recognize the conditions to the sides and rear of the vehicle 9. This ultimately improves driving safety. The first distance S11 and the third distance S13 may be distances along the emission direction of image light from the first display device 3. The second distance S12 and the fourth distance S14 may be distances along the direction in which image light is emitted from the second display device 4.

[0106] The display device 30 may be configured such that the first distance S11 and the second distance S12 of the first display device 3 and / or the second display device 4 are substantially equal to each other. In this case, the first image showing the side rear of the driver's seat and the second image showing the side rear of the passenger seat can be projected at substantially the same distance from the eyes of the driver 12. As a result, it becomes easier for the driver 12 to check the side rear of the vehicle 9, thereby improving driving safety.

[0107] The first distance S11 and the second distance S12 may be the same as long as the diopter difference is equal to or less than a predetermined value, which may be equal to or less than 0.2. In this case, the driver 12 can more easily view the first and second images, thereby further improving driving safety.

[0108] The display device 30 may be configured such that the size of the first image and the size of the second image are substantially the same in the first display device 3 and / or the second display device 4. In this case, the driver 12 can easily view the first image and the second image, thereby improving driving safety.

[0109] The size of the first image and the size of the second image do not need to be exactly the same. Within the field of view of the driver 12, the ratio of the horizontal size of the second image to the horizontal size of the first image may be, for example, 0.9 to 1.1, or 0.95 to 1.05. Furthermore, within the field of view of the driver 12, the ratio of the vertical size of the second image to the vertical size of the first image may be 0.9 to 1.1, or 0.95 to 1.05.

[0110] The invention according to the present disclosure has been described above based on the drawings and examples. However, the invention according to the present disclosure is not limited to the above-described embodiments. In other words, the invention according to the present disclosure can be variously changed, modified, or modified within the scope of the present disclosure, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the invention according to the present disclosure. For example, the functions contained in each component, etc. can be rearranged so as not to cause logical contradictions, and multiple components, etc. can be combined into one or divided. In other words, it should be noted that those skilled in the art can easily make various modifications or alterations based on the present disclosure. It should also be noted that these modifications, alterations, or alterations are included within the scope of the present disclosure.

[0111] The display device of the present disclosure can be implemented in the following aspects (1) to (22).

[0112] (1) A display device mounted on a vehicle, comprising: a first display device arranged near the driver's seat; and a second display device arranged near the passenger seat, wherein the first display device projects an image of the area behind the driver's seat as a virtual image into the driver's field of view; and the second display device projects an image of the area behind the passenger's seat as a real image into the driver's field of view.

[0113] (2) A display system mounted on a vehicle, comprising: a first imaging device that captures an image of the area behind the driver's seat; a second imaging device that captures an image of the area behind the passenger's seat; a first display device arranged near the driver's seat; a second display device arranged near the passenger's seat; and a control device, wherein the control device controls the first display device to project an image captured by the first imaging device as a virtual image within the driver's field of view, and controls the second display device to project an image captured by the second imaging device as a real image within the driver's field of view.

[0114] (3) When the distance between the driver's eye and the virtual image is a first distance, the distance between the driver's eye and the real image is a second distance, the distance between the driver's eye and the first display device is a third distance, and the distance between the driver's eye and the second display device is a fourth distance, the control device controls the first display device and / or the second display device so that the difference between the first distance and the third distance is greater than or equal to the difference between the second distance and the fourth distance, in the display system described in (2) above.

[0115] (4) A display system as described in (2) or (3) above, wherein when the distance between the driver's eye and the virtual image is a first distance and the distance between the driver's eye and the real image is a second distance, the control device controls the first display device and / or the second display device so that the second distance is greater than or equal to the first distance.

[0116] (5) A display system described in any of (2) to (4) above, wherein the control device controls the first display device and / or the second display device so that the magnification of the real image relative to the image displayed on the display surface of the display panel of the second display device is equal to or greater than the magnification of the virtual image relative to the image displayed on the display surface of the display panel of the first display device.

[0117] (6) A display system described in any of (2) to (5) above, wherein the control device controls the first display device and / or the second display device so that the size of the real image is equal to or greater than the size of the virtual image.

[0118] (7) Each of the first display device and the second display device comprises: a display panel; an optical system that projects an image displayed on the display panel as a real image or a virtual image into the field of view of the driver; and a drive unit that adjusts the relative position of the display panel and a focal point of the optical system on the display panel side, wherein the display panel emits linearly polarized image light having a polarization axis in a first direction, and the optical system comprises: a first semi-transparent mirror positioned at a distance from the display panel in the emission direction of the image light; a first retardation plate positioned between the display panel and the first semi-transparent mirror; a second retardation plate positioned on the opposite side of the first semi-transparent mirror from the first retardation plate; and a second semi-transparent mirror positioned between the display panel and the first retardation plate, the second semi-transparent mirror having a concave reflecting surface facing the first retardation plate, which transmits polarized light having a polarization axis in the first direction and reflects polarized light having a polarization axis in a second direction orthogonal to the first direction. The display system according to any one of (2) to (6), comprising: the first semi-transparent mirror, the first retardation plate, and a third semi-transparent mirror located on the opposite side of the second semi-transparent mirror with the second retardation plate therebetween, the third semi-transparent mirror having a concave reflective surface facing the second retardation plate, the third semi-transparent mirror reflecting polarized light having a polarization axis in the first direction and transmitting polarized light having a polarization axis in the second direction, wherein the first retardation plate and the second retardation plate are quarter-wave plates.

[0119] (8) The display system described in (7) above, wherein the control device controls the drive unit of the first display device to: approximately match the distance between the first semi-transparent mirror and the second semi-transparent mirror and the distance between the first semi-transparent mirror and the third semi-transparent mirror; and to make the distance between the display panel and the third semi-transparent mirror smaller than the focal length on the display panel side in the optical system; and the control device controls the drive unit of the second display device to: approximately match the distance between the first semi-transparent mirror and the second semi-transparent mirror and the distance between the first semi-transparent mirror and the third semi-transparent mirror; and to make the distance between the display panel and the third semi-transparent mirror larger than the focal length on the display panel side in the optical system.

[0120] (9) The first display device and the second display device each include: a display panel; an optical system that projects an image displayed on the display panel as a real image or a virtual image into the field of view of the driver; and a drive unit that adjusts the relative position of the display panel and a focal point of the optical system on the display panel side, wherein the display panel emits linearly polarized image light having a polarization axis in a first direction, and the optical system includes: a first semi-transparent mirror located at a distance from the display panel in the emission direction of the image light; a first retardation plate located between the display panel and the first semi-transparent mirror; a second retardation plate located on the opposite side of the first semi-transparent mirror from the first retardation plate; and a second semi-transparent mirror having a concave reflecting surface facing the first semi-transparent mirror via the first retardation plate or the second retardation plate, the second semi-transparent mirror transmitting polarized light having a polarization axis in the first direction and reflecting polarized light having a polarization axis in a second direction orthogonal to the first direction. The display system according to any one of (2) to (6), wherein the first retardation plate and the second retardation plate are quarter-wave plates.

[0121] (10) The display system described in (9) above, wherein the second semi-transparent mirror is positioned at a distance from the second retardation plate in the output direction, and the concave reflective surface of the second semi-transparent mirror faces the first semi-transparent mirror via the second retardation plate.

[0122] (11) The control device controls the driving unit of the first display device to make the distance between the display panel and the second semi-transparent mirror shorter than the focal length on the display panel side in the optical system, and the control device controls the driving unit of the second display device to make the distance between the display panel and the second semi-transparent mirror longer than the focal length on the display panel side in the optical system, in the display system described in (10) above.

[0123] (12) The display system described in (9) above, wherein the second semi-transparent mirror is located between the display panel and the first retardation film, and the concave reflective surface of the second semi-transparent mirror faces the first semi-transparent mirror via the first retardation film.

[0124] (13) The display system described in (12) above, wherein the control device controls the driving unit of the first display device so that the sum of twice the distance between the first semi-transparent mirror and the second semi-transparent mirror and the distance between the display panel and the second semi-transparent mirror is smaller than the focal length on the display panel side in the optical system, and the control device controls the driving unit of the second display device so that the sum of twice the distance between the first semi-transparent mirror and the second semi-transparent mirror and the distance between the display panel and the second semi-transparent mirror is larger than the focal length on the display panel side in the optical system.

[0125] (14) A display system mounted on a vehicle, comprising: a first imaging device that captures an image of an area to the rear of the driver's seat; a second imaging device that captures an image of an area to the rear of the passenger's seat; a first display device arranged near the driver's seat; a second display device arranged near the passenger's seat; and a control device, wherein the control device controls the first display device to project an image captured by the first imaging device as a first virtual image within the driver's field of view; and controls the second display device to project an image captured by the second imaging device as a second virtual image within the driver's field of view, and wherein when a distance between the driver's eyes and the first virtual image is a first distance, a distance between the driver's eyes and the second virtual image is a second distance, a distance between the driver's eyes and the first display device is a third distance, and a distance between the driver's eyes and the second display device is a fourth distance, the control device controls the first display device and / or the second display device so that a difference between the first distance and the third distance is equal to or greater than a difference between the second distance and the fourth distance.

[0126] (15) The first display device and the second display device each include: a display panel; an optical system that projects an image displayed on the display panel as a real image or a virtual image into the field of view of the driver; and a drive unit that adjusts the relative position of the display panel and a focal point of the optical system on the display panel side, wherein the display panel emits linearly polarized image light having a polarization axis in a first direction, and the optical system includes: a first semi-transparent mirror located at a distance from the display panel in the emission direction of the image light; a first retardation plate located between the display panel and the first semi-transparent mirror; a second retardation plate located on the opposite side of the first semi-transparent mirror from the first retardation plate; and a second semi-transparent mirror located between the display panel and the first retardation plate, the second semi-transparent mirror having a concave reflecting surface facing the first retardation plate, which transmits polarized light having a polarization axis in the first direction and reflects polarized light having a polarization axis in a second direction orthogonal to the first direction. The display system according to (14) above, comprising: the first semi-transparent mirror, the first retardation plate, and a third semi-transparent mirror located on the opposite side of the second semi-transparent mirror across the second retardation plate, the third semi-transparent mirror having a concave reflective surface facing the second retardation plate, the third semi-transparent mirror reflecting polarized light having a polarization axis in the first direction and transmitting polarized light having a polarization axis in the second direction, wherein the first retardation plate and the second retardation plate are quarter-wave plates.

[0127] (16) The display system described in (15) above, wherein the control device controls the drive unit of the first display device to: approximately match the distance between the first semi-transparent mirror and the second semi-transparent mirror and the distance between the first semi-transparent mirror and the third semi-transparent mirror; and to make the distance between the display panel and the third semi-transparent mirror shorter than the focal length on the display panel side in the optical system; and the control device controls the drive unit of the second display device to: approximately match the distance between the first semi-transparent mirror and the second semi-transparent mirror and the distance between the first semi-transparent mirror and the third semi-transparent mirror; and to make the distance between the display panel and the third semi-transparent mirror shorter than the focal length on the display panel side in the optical system.

[0128] (17) The first display device and the second display device each include: a display panel; an optical system that projects an image displayed on the display panel as a real image or a virtual image into the field of view of the driver; and a drive unit that adjusts the relative position of the display panel and a focal point of the optical system on the display panel side, wherein the display panel emits linearly polarized image light having a polarization axis in a first direction, and the optical system includes: a first semi-transparent mirror located at a distance from the display panel in the emission direction of the image light; a first retardation plate located between the display panel and the first semi-transparent mirror; a second retardation plate located on the opposite side of the first semi-transparent mirror from the first retardation plate; and a second semi-transparent mirror having a concave reflecting surface facing the first semi-transparent mirror via the first retardation plate or the second retardation plate, which transmits polarized light having a polarization axis in the first direction and reflects polarized light having a polarization axis in a second direction orthogonal to the first direction. The display system according to (14), wherein the first retardation plate and the second retardation plate are quarter-wave plates.

[0129] (18) The display system described in (17) above, wherein the second semi-transparent mirror is positioned away from the second retardation plate in the output direction, and the concave reflective surface of the second semi-transparent mirror faces the first semi-transparent mirror via the second retardation plate.

[0130] (19) The display system described in (18) above, wherein the control device controls the driving units of the first display device and the second display device so that the distance between the display panel and the second semi-transparent mirror is shorter than the focal length on the display panel side in the optical system.

[0131] (20) The display system described in (17) above, wherein the second semi-transparent mirror is located between the display panel and the first retardation film, and the concave reflective surface of the second semi-transparent mirror faces the first semi-transparent mirror via the first retardation film.

[0132] (21) The display system described in (20) above, wherein the control device controls the driving units of the first display device and the second display device so that the sum of twice the distance between the first semi-transparent mirror and the second semi-transparent mirror and the distance between the display panel and the second semi-transparent mirror is smaller than the focal length on the display panel side in the optical system.

[0133] (22) A display device mounted on a vehicle, comprising: a first display device arranged near a driver's seat; and a second display device arranged near a passenger seat, wherein the first display device projects an image of the area behind the driver's seat as a first image into the driver's field of view; and the second display device projects an image of the area behind the passenger's seat as a second image into the driver's field of view, wherein when the distance between the driver's eyes and the first image is a first distance, the distance between the driver's eyes and the second image is a second distance, the distance between the driver's eyes and the first display device is a third distance, and the distance between the driver's eyes and the second display device is a fourth distance, the first display device and / or the second display device sets the difference between the first distance and the third distance to be equal to or greater than the difference between the second distance and the fourth distance.

[0134] The display device of the present disclosure makes it easier for the driver to see the left and right rear of the vehicle.

[0135] REFERENCE SIGNS LIST 1 First imaging device 2 Second imaging device 3 First display device 4 Second display device 5 Control device 6 Display panel 6a Display surface 7 Optical system 8 Drive unit 9 Mobile body (vehicle) 9a A-pillar 9a Reflecting surface 9b A-pillar 10 Third semi-transparent mirror 12 Driver 13 Illuminator 14 First semi-transparent mirror 14a Reflecting surface 14b Reflecting surface 15 Second semi-transparent mirror 15a Reflecting surface 16 Third semi-transparent mirror 16a Reflecting surface 17 First retardation plate 18 Second retardation plate 19 Optical system 20 First semi-transparent mirror 20a Reflecting surface 20b Reflecting surface 21 Second semi-transparent mirror 21a Reflecting surface 22 First retardation plate 23 Second retardation plate 24 Optical system 25 First semi-transparent mirror 25a Reflecting surface 26 Second semi-transmitting mirror 26a Reflecting surface 27 First retardation plate 28 Second retardation plate 30 Display device 50 Display system

Claims

1. A display device mounted on a vehicle, comprising: a first display device arranged near the driver's seat; and a second display device arranged near the passenger seat, wherein the first display device projects an image of the area behind the driver's seat as a virtual image into the driver's field of vision, and the second display device projects an image of the area behind the passenger's seat as a real image into the driver's field of vision.

2. A display system mounted on a vehicle, comprising: a first imaging device that captures an image of the area behind the driver's seat; a second imaging device that captures an image of the area behind the passenger's seat; a first display device arranged near the driver's seat; a second display device arranged near the passenger's seat; and a control device, wherein the control device controls the first display device to project an image captured by the first imaging device as a virtual image within the driver's field of vision, and controls the second display device to project an image captured by the second imaging device as a real image within the driver's field of vision.

3. The display system of claim 2, wherein when the distance between the driver's eye and the virtual image is a first distance, the distance between the driver's eye and the real image is a second distance, the distance between the driver's eye and the first display device is a third distance, and the distance between the driver's eye and the second display device is a fourth distance, the control device controls the first display device and / or the second display device so that the difference between the first distance and the third distance is greater than or equal to the difference between the second distance and the fourth distance.

4. A display system as described in claim 2 or 3, wherein when the distance between the driver's eye and the virtual image is a first distance and the distance between the driver's eye and the real image is a second distance, the control device controls the first display device and / or the second display device so that the second distance is equal to or greater than the first distance.

5. A display system according to any one of claims 2 to 4, wherein the control device controls the first display device and / or the second display device so that the magnification of the real image relative to the image displayed on the display surface of the display panel of the second display device is equal to or greater than the magnification of the virtual image relative to the image displayed on the display surface of the display panel of the first display device.

6. A display system according to any one of claims 2 to 5, wherein the control device controls the first display device and / or the second display device so that the size of the real image is equal to or larger than the size of the virtual image.

7. The first display device and the second display device each comprise: a display panel; an optical system that projects an image displayed on the display panel as a real image or a virtual image into the field of view of the driver; and a drive unit that adjusts the relative position of the display panel and the focal point of the optical system on the display panel side, wherein the display panel emits linearly polarized image light having a polarization axis in a first direction, and the optical system comprises: a first semi-transparent mirror located at a distance from the display panel in the emission direction of the image light; a first retardation plate located between the display panel and the first semi-transparent mirror; a second retardation plate located on the opposite side of the first semi-transparent mirror from the first retardation plate; and a second semi-transparent mirror located between the display panel and the first retardation plate, the second semi-transparent mirror having a concave reflecting surface facing the first retardation plate, which transmits polarized light having a polarization axis in the first direction and reflects polarized light having a polarization axis in a second direction perpendicular to the first direction.

7. The display system according to claim 2, comprising: the first semi-transparent mirror, the first retardation plate, and a third semi-transparent mirror located on the opposite side of the second semi-transparent mirror with the second retardation plate therebetween, the third semi-transparent mirror having a concave reflective surface facing the second retardation plate, the third semi-transparent mirror reflecting polarized light having a polarization axis in the first direction and transmitting polarized light having a polarization axis in the second direction; wherein the first retardation plate and the second retardation plate are quarter-wave plates.

8. The display system described in claim 7, wherein the control device controls the drive unit of the first display device to make the distance between the first semi-transparent mirror and the second semi-transparent mirror approximately equal to the distance between the first semi-transparent mirror and the third semi-transparent mirror, and to make the distance between the display panel and the third semi-transparent mirror smaller than the focal length on the display panel side in the optical system; and the control device controls the drive unit of the second display device to make the distance between the first semi-transparent mirror and the second semi-transparent mirror approximately equal to the distance between the first semi-transparent mirror and the third semi-transparent mirror, and to make the distance between the display panel and the third semi-transparent mirror larger than the focal length on the display panel side in the optical system.

9. The first display device and the second display device each include a display panel, an optical system that projects an image displayed on the display panel as a real image or a virtual image into the driver's field of vision, and a drive unit that adjusts the relative position of the display panel and a focal point of the optical system on the display panel side, wherein the display panel emits linearly polarized image light having a polarization axis in a first direction, and the optical system includes a first semi-transparent mirror located at a distance from the display panel in the emission direction of the image light, a first retardation plate located between the display panel and the first semi-transparent mirror, a second retardation plate located on the opposite side of the first semi-transparent mirror from the first retardation plate, and a second semi-transparent mirror having a concave reflecting surface facing the first semi-transparent mirror via the first retardation plate or the second retardation plate, which transmits polarized light having a polarization axis in the first direction and reflects polarized light having a polarization axis in a second direction perpendicular to the first direction, 7. The display system according to claim 2, wherein the first retardation plate and the second retardation plate are quarter-wave plates.

10. The display system of claim 9, wherein the second semi-transparent mirror is positioned at a distance from the second retardation plate in the emission direction, and the concave reflecting surface of the second semi-transparent mirror faces the first semi-transparent mirror via the second retardation plate.

11. A display system as described in claim 10, wherein the control device controls the drive unit of the first display device to make the distance between the display panel and the second semi-transparent mirror shorter than the focal length on the display panel side in the optical system, and the control device controls the drive unit of the second display device to make the distance between the display panel and the second semi-transparent mirror longer than the focal length on the display panel side in the optical system.

12. The display system of claim 9, wherein the second semi-transparent mirror is located between the display panel and the first retardation film, and the concave reflective surface of the second semi-transparent mirror faces the first semi-transparent mirror via the first retardation film.

13. The display system described in claim 12, wherein the control device controls the drive unit of the first display device so that the sum of twice the distance between the first semi-transparent mirror and the second semi-transparent mirror and the distance between the display panel and the second semi-transparent mirror is smaller than the focal length on the display panel side in the optical system, and the control device controls the drive unit of the second display device so that the sum of twice the distance between the first semi-transparent mirror and the second semi-transparent mirror and the distance between the display panel and the second semi-transparent mirror is larger than the focal length on the display panel side in the optical system.

14. A display system mounted on a vehicle, comprising: a first imaging device that captures an image to the side and rear of the driver's seat; a second imaging device that captures an image to the side and rear of the passenger's seat; a first display device arranged near the driver's seat; a second display device arranged near the passenger's seat; and a control device, wherein the control device controls the first display device to project an image captured by the first imaging device as a first virtual image within the driver's field of view, and controls the second display device to project an image captured by the second imaging device as a second virtual image within the driver's field of view, and wherein when the distance between the driver's eyes and the first virtual image is a first distance, the distance between the driver's eyes and the second virtual image is a second distance, the distance between the driver's eyes and the first display device is a third distance, and the distance between the driver's eyes and the second display device is a fourth distance, the control device controls the first display device and / or the second display device so that the difference between the first distance and the third distance is equal to or greater than the difference between the second distance and the fourth distance.

15. The first display device and the second display device each comprise: a display panel; an optical system that projects an image displayed on the display panel as a real image or a virtual image into the field of view of the driver; and a drive unit that adjusts the relative position of the display panel and a focal point of the optical system on the display panel side, wherein the display panel emits linearly polarized image light having a polarization axis in a first direction, and the optical system comprises: a first semi-transparent mirror located at a distance from the display panel in the emission direction of the image light; a first retardation plate located between the display panel and the first semi-transparent mirror; a second retardation plate located on the opposite side of the first semi-transparent mirror from the first retardation plate; and a second semi-transparent mirror located between the display panel and the first retardation plate and having a concave reflecting surface facing the first retardation plate, the second semi-transparent mirror transmitting polarized light having a polarization axis in the first direction and reflecting polarized light having a polarization axis in a second direction perpendicular to the first direction.

15. The display system according to claim 14, comprising: the first semi-transparent mirror, the first retardation plate, and a third semi-transparent mirror located on the opposite side of the second semi-transparent mirror with the second retardation plate therebetween, the third semi-transparent mirror having a concave reflective surface facing the second retardation plate, the third semi-transparent mirror reflecting polarized light having a polarization axis in the first direction and transmitting polarized light having a polarization axis in the second direction, wherein the first retardation plate and the second retardation plate are quarter-wave plates.

16. The display system described in claim 15, wherein the control device controls the drive unit of the first display device to: approximately match the distance between the first semi-transparent mirror and the second semi-transparent mirror and the distance between the first semi-transparent mirror and the third semi-transparent mirror; and to make the distance between the display panel and the third semi-transparent mirror shorter than the focal length on the display panel side in the optical system; and the control device controls the drive unit of the second display device to: approximately match the distance between the first semi-transparent mirror and the second semi-transparent mirror and the distance between the first semi-transparent mirror and the third semi-transparent mirror; and to make the distance between the display panel and the third semi-transparent mirror shorter than the focal length on the display panel side in the optical system.

17. The first display device and the second display device each include a display panel, an optical system that projects an image displayed on the display panel as a real image or a virtual image into the driver's field of vision, and a drive unit that adjusts the relative position of the display panel and the focal point of the optical system on the display panel side, wherein the display panel emits linearly polarized image light having a polarization axis in a first direction, and the optical system includes a first semi-transparent mirror located at a distance from the display panel in the emission direction of the image light, a first retardation plate located between the display panel and the first semi-transparent mirror, a second retardation plate located on the opposite side of the first semi-transparent mirror from the first retardation plate, and a second semi-transparent mirror having a concave reflecting surface facing the first semi-transparent mirror via the first retardation plate or the second retardation plate, which transmits polarized light having a polarization axis in the first direction and reflects polarized light having a polarization axis in a second direction perpendicular to the first direction, 15. The display system of claim 14, wherein the first retarder and the second retarder are quarter wave plates.

18. The display system of claim 17, wherein the second semi-transparent mirror is positioned at a distance from the second retardation plate in the emission direction, and the concave reflecting surface of the second semi-transparent mirror faces the first semi-transparent mirror via the second retardation plate.

19. The display system of claim 18, wherein the control device controls the drive units of the first display device and the second display device so that the distance between the display panel and the second semi-transparent mirror is shorter than the focal length of the optical system on the display panel side.

20. The display system of claim 17, wherein the second semi-transparent mirror is located between the display panel and the first retardation film, and the concave reflective surface of the second semi-transparent mirror faces the first semi-transparent mirror via the first retardation film.

21. A display system as described in claim 20, wherein the control device controls the drive units of the first display device and the second display device so that the sum of twice the distance between the first semi-transparent mirror and the second semi-transparent mirror and the distance between the display panel and the second semi-transparent mirror is smaller than the focal length on the display panel side in the optical system.

22. A display device mounted on a vehicle, comprising: a first display device arranged near the driver's seat; and a second display device arranged near the passenger seat, wherein the first display device projects an image of the area behind the driver's seat as a first image into the driver's field of view; and the second display device projects an image of the area behind the passenger's seat as a second image into the driver's field of view, wherein when the distance between the driver's eyes and the first image is a first distance, the distance between the driver's eyes and the second image is a second distance, the distance between the driver's eyes and the first display device is a third distance, and the distance between the driver's eyes and the second display device is a fourth distance, the first display device and / or the second display device sets the difference between the first distance and the third distance to be equal to or greater than the difference between the second distance and the fourth distance.

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