AERIAL IMAGE DISPLAY DEVICE

An aerial image display device includes a display, an imaging optical system including a freeform mirror including first and second portions, and a drive. The freeform mirror reflects light incident on the first portion with a first object focal point and light incident on the second portion with a second object focal point having a shorter focal length than the first object focal point. A first positioning is relative positioning of the display and the freeform mirror with the display closer to the freeform mirror than the first object focal point to display a virtual image in air. A second positioning is the relative positioning of the display and the freeform mirror with the display farther from the freeform mirror than the second object focal point to display a real image in air. The drive changes a spatial position of the display from the first to second or second to first positioning.

TECHNICAL FIELD

The present disclosure relates to an aerial image display device.

BACKGROUND OF INVENTION

A known technique is described in, for example, Patent Literature 1.

CITATION LIST

Patent Literature

SUMMARY

In one embodiment of the present disclosure, an aerial image display device includes a display that displays an image with traveling image light, an imaging optical system including one or more optical elements to receive the traveling image light as incident light and having a first object focal point and a second object focal point with a shorter focal length than the first object focal point, and a drive that changes positional relationship between the first object focal point and the display relative to each other or between the second object focal point and the display relative to each other. The drive switches between a first positioning and a second positioning. The first positioning is positioning with the display located closer to the imaging optical system than the first object focal point of the imaging optical system to display a virtual image in air. The second positioning is positioning with the display located farther from the imaging optical system than the second object focal point of the imaging optical system to display a real image in air.

DESCRIPTION OF EMBODIMENTS

An aerial image display device with the structure that forms the basis of an aerial image display device according to one or more embodiments of the present disclosure will now be described.

A known display device described in Patent Literature 1 forms an aerial image from light emitted from a display using an optical element such as a retroreflector.

For example, a display that displays a real image in the air and a display that displays a virtual image in the air may be used to display an image as a real image and a virtual image in a manner switching between them. This structure thus includes two displays.

One or more aspects of the present disclosure are directed to an aerial image display device that can display a real image and a virtual image in the air.

One or more embodiments of the present disclosure will now be described with reference to the drawings. The drawings used herein are schematic and are not drawn to scale relative to the actual size of each component.

FIG.1is a schematic diagram of an aerial image display device according to a first embodiment illustrating its structure. An aerial image display device1includes a display10, an imaging optical system20, and a drive30. The aerial image display device1may include an internal controller40. The aerial image display device1may also be controlled by an external controller40.

The display10displays an image using traveling image light. The controller40changes the image to be displayed on the display10. The display10may be a transmissive display or a self-luminous display. For example, the transmissive display may be a liquid crystal display. For example, the self-luminous display may be a display including a self-luminous element such as a light-emitting diode (LED) element, an organic electroluminescent (OEL) element, an organic LED (OLED) element, or a semiconductor laser diode (LD) element, or a digital micromirror device (DMD).

The imaging optical system20receives image light as incident light. The imaging optical system20includes one or more optical elements. The imaging optical system20may be a reflective optical system including an optical element that is a light-reflecting member, such as a reflective mirror. The imaging optical system20may be a catadioptric optical system including an optical element that is a light-reflecting member, such as a reflective mirror, and a member that refracts light, such as a lens. The imaging optical system20may be a reflective or catadioptric optical system that is a coaxial optical system. The imaging optical system20may be a reflective or catadioptric optical system that is a non-coaxial optical system. The non-coaxial optical system may be, for example, a decentered optical system, or may be an off-axial optical system.

The imaging optical system20includes the display10as a light source. The imaging optical system20includes an object space containing the display10and an image space opposite to the object space. The imaging optical system20includes an object focal point as a focal point in the object space, and an image focal point as a focal point in the image space. In the present embodiment, the imaging optical system20has a first object focal point with a relatively long focal length and a second object focal point with a relatively short focal length. The imaging optical system20may use, for example, a freeform mirror21as an optical element. In the present embodiment, the freeform mirror21includes a first portion21A and a second portion21B. The first portion21A of the freeform mirror21includes a focal point as a first object focal point f1. The freeform mirror21reflects light incident on the first portion21A with a focal point at the first object focal point f1. The second portion21B of the freeform mirror21includes a focal point as a second object focal point f2. The freeform mirror21reflects light incident on the second portion21B with a focal point at the second object focal point f2. The first object focal point f1has a longer focal length than the second object focal point f2. The second object focal point f2has a shorter focal length than the first object focal point f1.

FIG.2is a schematic diagram of the aerial image display device according to the first embodiment illustrating its operation example. In the present embodiment, for example, the imaging optical system20includes an optical element that is a single freeform mirror21. When the display10is located closer to the imaging optical system20than the first object focal point f1of the imaging optical system20, a virtual image V corresponding to image light is displayed in the air in the image space as an image corresponding to the display10. The relative positioning of the display10and the freeform mirror21with the display10located closer to the freeform mirror21than the first object focal point f1to display a virtual image V in the air is referred to as first positioning. The first positioning indicating the positional relationship between the display10and the object focal point f of the imaging optical system20is relative positioning to display a virtual image V in the air. When the display10is located farther from the imaging optical system20than the second object focal point f2of the imaging optical system20, a real image R corresponding to the image light is displayed in the air in the image space as an image corresponding to the display10. The relative positioning of the display10and the freeform mirror21with the display10located farther from the freeform mirror21than the second object focal point f2to display a real image R in the air is referred to as second positioning. The second positioning indicating the positional relationship between the display10and the object focal point f of the imaging optical system20is relative positioning to display a real image R in the air. The first positioning and the second positioning may be referred to as first relative positioning and second relative positioning.

The drive30changes the positional relationship between the focal point of the imaging optical system20and the display10relative to each other. The drive30changes the positions of the display10and the imaging optical system20relative to each other. The drive30changes, for example, the position of at least the display10or at least one of the optical elements in the imaging optical system20to change their relative positions. The drive30may change, for example, the positions of all optical elements in the imaging optical system20to change their positions relative to the display10. The drive30may change, for example, the positions of one or more optical elements in the imaging optical system20to change the positional relationship between the focal point of the imaging optical system20and the display10relative to each other.

The controller40controls the display10, and may be, for example, a processor. The controller40may include one or more processors. The processors may include a general-purpose processor that reads a specific program to perform a specific function, and a processor dedicated to specific processing. The dedicated processor may include an application-specific integrated circuit (ASIC). The processors may include a programmable logic device (PLD). The PLD may include a field-programmable gate array (FPGA). The controller40may be either a system on a chip (SoC) or a system in a package (SiP) in which one or more processors cooperate with other components. The controller40may control the operation of the drive30. The controller40may function as a controller for controlling the operation of the drive30. The function of the controller for controlling the operation of the drive30may be a motor driver for controlling a drive motor. A controller other than the controller40may control the operation of the drive30. The controller other than the controller40may be an integrated circuit (IC) for motor control.

The controller40may perform control to enlarge the image (also referred to as a virtual-use image) to be displayed on the display10for displaying a virtual image V in the air relative to the image (also referred to as a real-use image) to be displayed on the display10for displaying a real image R in the air. In this case, the virtual image V is formed behind the freeform mirror21as viewed from the user. Thus, the virtual image V is located farther from the user than the real image R displayed in the air. The virtual image V is thus less viewable to the user than the real image R. In addition, viewing the virtual image V through the semi-transmissive freeform mirror21or a windshield25(illustrated inFIG.8) of a transport vehicle further causes the virtual image V to be less viewable to the user than the real image R. The above control reduces the likelihood of the virtual image V being less viewable to the user than the real image R. The ratio of enlargement of the virtual-use image to the real-use image may be, but not limited to, more than one time and about three times or less.

The controller40may perform control to cause the luminance of the image to be displayed on the display10for displaying a virtual image V in the air to be higher than the luminance of the image to be displayed on the display10for displaying a real image R in the air. This also reduces the likelihood of the virtual image V being less viewable to the user than the real image R. The luminance of the virtual-use image may be, but not limited to, more than one time and about ten times or less the luminance of the real-use image.

The controller40may perform control to cause the contrast of the image to be displayed on the display10for displaying a virtual image V in the air to be higher than the contrast of the image to be displayed on the display10for displaying a real image R in the air. This also reduces the likelihood of the virtual image V being less viewable to the user than the real image R. The contrast of the virtual-use image may be, but not limited to, more than one time and about twice or less the contrast of the real-use image.

The controller40may perform control to cause the frame frequency of the image to be displayed on the display10for displaying a virtual image V in the air to be higher than the frame frequency of the image to be displayed on the display10for displaying a real image R in the air. This also reduces the likelihood of the virtual image V being less viewable to the user than the real image R. The frame frequency of the virtual-use image may be, but not limited to, more than one time and about eight times or less the frame frequency of the real-use image. For example, when the frame frequency of the real-use image is 30 Hz, the frame frequency of the virtual-use image may be higher than 30 Hz and about 240 Hz or lower.

In the present embodiment, the drive30can control shifts from the first positioning to the second positioning and from the second positioning to the first positioning by, for example, changing the spatial position of the display10. The movements of the display10in the present embodiment are rotational. For example, the display10includes a rotational shaft at its center, and the display10is rotated about the shaft. The direction of image light emitted from the display10can thus be changed. In the present embodiment, the position of the freeform mirror21may be fixed. The drive30may have any structure that allows the display10to move between a first spatial position corresponding to the first positioning and a second spatial position corresponding to the second positioning from one position to the other. Examples of such a structure include an electric slider and an electric cylinder controlled by, for example, a servo motor. The drive30may stop the display10at two positions that are the first spatial position and the second spatial position. The drive30may stop the display10at the two positions, or the first spatial position and the second spatial position, or at any position between the first spatial position and the second spatial position.

In one or more embodiments of the present disclosure, the first spatial position is a spatial position corresponding to the first positioning, and the second spatial position is a spatial position corresponding to the second positioning. The first spatial position and the second spatial position may indicate the spatial positions of one or more components, which may vary between embodiments. For example, the first spatial position and the second spatial position may indicate the spatial positions of the display10, the imaging optical system20, and one or more optical elements in the imaging optical system20.

When the display10is rotated to the first spatial position, the first portion21A of the freeform mirror21reflects image light. The display10is located closer to the freeform mirror21than the first object focal point f1. When the display10is rotated to the second spatial position, the second portion21B of the freeform mirror21reflects image light. The display10is located farther from the freeform mirror21than the second object focal point f2.

The user of the aerial image display device1can view a virtual image V when the display10is at the first spatial position, and can view a real image R when the display10is at the second spatial position. In the present embodiment, the aerial image display device1can thus display a real image R and a virtual image V in the air as the drive30changes the positions of the display10and the optical element relative to each other.

FIG.3is a schematic diagram of an aerial image display device according to a second embodiment illustrating its structure and operation example. In the present embodiment, as in the first embodiment, the imaging optical system20in the aerial image display device1includes an optical element that is a freeform mirror21. In the present embodiment, the drive30can control shifts from the first positioning to the second positioning and from the second positioning to the first positioning by, for example, changing the spatial position of the freeform mirror21. In the present embodiment, the drive30can move the freeform mirror21to the first spatial position and to the second spatial position. The movements of the freeform mirror21in the present embodiment are translational. In the present embodiment, the position of the display10may be fixed. The drive30may have any structure that allows the freeform mirror21to move between the first spatial position and the second spatial position from one position to the other. Examples of such a structure include an electric slider and an electric cylinder. The drive30may stop the freeform mirror21at two positions that are the first spatial position and the second spatial position. The drive30may stop the freeform mirror21at the two positions, or the first spatial position and the second spatial position, or at any position between the first spatial position and the second spatial position.

When the freeform mirror21is translated to the first spatial position, the first portion21A of the freeform mirror21reflects image light. The display10is located closer to the freeform mirror21than the first object focal point f1. When the freeform mirror21is translated to the second spatial position, the second portion21B of the freeform mirror21reflects image light. The display10is located farther from the freeform mirror21than the second object focal point f2.

The user of the aerial image display device1can view a virtual image V when the freeform mirror21is at the first spatial position, and can view a real image R when the freeform mirror21is at the second spatial position. In the present embodiment, the aerial image display device1can thus display a real image R and a virtual image V in the air as the drive30changes the positions of the display10and the optical element relative to each other.

A real image R and a virtual image V viewable to the user may be the same or different images. For different images, the controller40displays an image to be viewed by the user as a virtual image V when the display10or the optical element is at the first positioning, and displays an image to be viewed by the user as a real image R when the display10or the optical element is at the second positioning. Thus, the user receives different information from the real image R and the virtual image V displayed in the air.

The real image R is an inverted image and the virtual image V is an erect image. Thus, the controller40switches, for example, the up-down orientation of the image to be displayed on the display10between orientation for the first positioning and the orientation for the second positioning. The controller40reads, for example, an image with a different up-down orientation from a storage and causes the image to be displayed on the display10. Thus, when the real image R and the virtual image V are switched between them, the user can view the image displayed in the correct up-down orientation in the air.

When a displayed image is distorted, the display10may display an image with correction to reduce such distortion caused by an optical element. The distortion may be corrected using, for example, predefined distortion correction tables. With the real image R being an inverted image and the virtual image V being an erect image, the distortion correction tables may include a real image correction table and a virtual image correction table. The controller40may switch, for example, the distortion correction table between the distortion correction table for the first positioning and the distortion correction table for the second positioning. The controller40may use, for example, different distortion correction tables for the first positioning and for the second positioning. Thus, the aerial image display device1switching between a real image R and a virtual image V can provide images corrected for distortion to the user.

FIG.4is a schematic diagram of an aerial image display device according to a third embodiment illustrating its structure and operation example. In the present embodiment, as in the first embodiment, the imaging optical system20in the aerial image display device1includes an optical element that is a freeform mirror21. In the present embodiment, the drive30can control shifts from the first positioning to the second positioning and from the second positioning to the first positioning by, for example, changing the spatial position of the freeform mirror21. In the present embodiment, the drive30can move the freeform mirror21to the first spatial position and to the second spatial position. The movements of the freeform mirror21in the present embodiment are rotational. For example, the freeform mirror21includes a rotational shaft at its one end, and the freeform mirror21is rotated about the shaft. In the present embodiment, the position of the display10may be fixed. The drive30may have any structure that allows the freeform mirror21to move between the first spatial position and the second spatial position from one position to the other. Examples of such a structure include an electric slider and an electric cylinder. The drive30may stop the freeform mirror21at two positions that are the first spatial position and the second spatial position. The drive30may stop the freeform mirror21at the two positions, or the first spatial position and the second spatial position, or at any position between the first spatial position and the second spatial position.

When the freeform mirror21is rotated to the first spatial position, the first portion21A of the freeform mirror21reflects image light. The display10is located closer to the freeform mirror21than the first object focal point f1. When the freeform mirror21is rotated to the second spatial position, the second portion21B of the freeform mirror21reflects image light. The display10is located farther from the freeform mirror21than the second object focal point f2.

The user of the aerial image display device1can view a virtual image V when the freeform mirror21is at the first spatial position, and can view a real image R when the freeform mirror21is at the second spatial position. In the present embodiment, the aerial image display device1can thus display a real image R and a virtual image V in the air as the drive30changes the positions of the display10and the optical element relative to each other.

FIG.5is a schematic diagram of an aerial image display device according to a fourth embodiment illustrating its structure and operation example. In the present embodiment, the imaging optical system20in the aerial image display device1includes optical elements that are a freeform mirror21and a plane mirror22. In the present embodiment, the drive30can control shifts from the first positioning to the second positioning and from the second positioning to the first positioning by, for example, changing the spatial position of the display10. In the present embodiment, the drive30can move the freeform mirror21to the first spatial position and to the second spatial position. The movements of the display10in the present embodiment are rotational. In the present embodiment, the positions of the freeform mirror21and the plane mirror22may be fixed. The drive30may have any structure that allows the display10to move between the first spatial position and the second spatial position from one position to the other. Examples of such a structure include an electric slider and an electric cylinder. The drive30may stop the display10at two positions that are the first spatial position and the second spatial position. The drive30may stop the display10at the two positions, or the first spatial position and the second spatial position, or at any position between the first spatial position and the second spatial position.

When the display10is rotated to the first spatial position, the plane mirror22reflects image light. The first portion21A of the freeform mirror21reflects image light reflected from the plane mirror22. The display10is located closer to the optical elements than the first object focal point f1. When the display10is rotated to the second spatial position, the plane mirror22reflects image light. The second portion21B of the freeform mirror21reflects image light reflected from the plane mirror22. The display10is located farther from the optical elements than the second object focal point f2.

The user of the aerial image display device1can view a virtual image V when the display10is at the first spatial position, and can view a real image R when the display10is at the second spatial position. In the present embodiment, the aerial image display device1can thus display a real image R and a virtual image V in the air as the drive30changes the positions of the display10and the optical elements relative to one another.

FIG.6is a schematic diagram of an aerial image display device according to a fifth embodiment illustrating its structure and operation example. In the present embodiment, the imaging optical system20in the aerial image display device1includes optical elements that are a freeform mirror21and a plane mirror22. In the present embodiment, the drive30can control shifts from the first positioning to the second positioning and from the second positioning to the first positioning by, for example, changing the spatial position of the plane mirror22. In the present embodiment, the drive30can move the plane mirror22to the first spatial position and to the second spatial position. The movements of the plane mirror22in the present embodiment are translational. In the present embodiment, the position of the display10may be fixed. The Drive30may have any structure that allows the plane mirror22to move between the first spatial position and the second spatial position from one position to the other. Examples of such a structure include an electric slider and an electric cylinder. The drive30may stop the plane mirror22at two positions that are the first spatial position and the second spatial position. The drive30may stop the plane mirror22at the two positions, or the first spatial position and the second spatial position, or at any position between the first spatial position and the second spatial position.

When the display10is translated to the first spatial position, the plane mirror22reflects image light. The first portion21A of the freeform mirror21reflects image light reflected from the plane mirror22. The display10is located closer to the optical elements than the first object focal point f1. When the display10is translated to the second spatial position, the plane mirror22reflects image light. The second portion21B of the freeform mirror21reflects image light reflected from the plane mirror22. The display10is located farther from the optical elements than the second object focal point f2.

The user of the aerial image display device1can view a virtual image V when the plane mirror22is at the first spatial position, and can view a real image R when the plane mirror22is at the second spatial position. In the present embodiment, the aerial image display device1can thus display a real image R and a virtual image V in the air as the drive30changes the positions of the display10and the optical elements relative to one another.

FIG.7is a schematic diagram of an aerial image display device according to a sixth embodiment illustrating its structure and operation example. In the present embodiment, an imaging optical system20A in an aerial image display device1A includes optical elements that are a freeform mirror21and a lens24. The lens24may be, for example, a convex lens, a Fresnel lens, or a liquid crystal lens. An imaging optical system20A in the present embodiment is a catadioptric optical system. In the present embodiment, the drive30can control shifts from the first positioning to the second positioning and from the second positioning to the first positioning by, for example, changing the spatial position of the lens24. In the present embodiment, the drive30can move the lens24to the first spatial position and to the second spatial position. The movements of the lens24in the present embodiment are rotational. In the present embodiment, the position of the display10may be fixed. The drive30may have any structure that allows the lens24to move between the first spatial position and the second spatial position from one position to the other. Examples of such a structure include an electric slider and an electric cylinder. The drive30may stop the lens24at two positions that are the first spatial position and the second spatial position. The drive30may stop the lens24at the two positions, or the first spatial position and the second spatial position, or at any position between the first spatial position and the second spatial position.

The user of the aerial image display device1can view a virtual image V when the lens24is at the first spatial position, and can view a real image R when the lens24is at the second spatial position. In the present embodiment, the aerial image display device1can thus display a real image R and a virtual image V in the air as the drive30changes the positions of the display10and the optical elements relative to one another.

When the imaging optical system20A is a catadioptric optical system, as in the present embodiment, the lens24may be changed instead of moving the lens24. For example, the drive30may move two lenses24with different lens characteristics to change between these lenses24. The drive30may change the lens24to change the position of the freeform mirror21on which the image light is incident. Thus, the drive30can switch between the first positioning in which the display10is located closer to the imaging optical system20A than the first object focal point f1and the second positioning in which the display10is located farther from the imaging optical system20A than the second object focal point f2.

FIG.8is a schematic diagram of an aerial image display device according to a seventh embodiment illustrating its structure and operation example. In the present embodiment, an aerial image display device1B is mounted on a movable body. The aerial image display device1B includes a display10, an imaging optical system20B, a drive30, a controller40, and a camera50. The aerial image display device1B may be at any position inside or outside the movable body. The aerial image display device1B may be installed, for example, inside a dashboard in the movable body.

In one or more embodiments of the present disclosure, examples of the movable body include a vehicle, a vessel, and an aircraft. Examples of the vehicle include an automobile, an industrial vehicle, a railroad vehicle, a community vehicle, and a fixed-wing aircraft traveling on a runway. Examples of the automobile include a passenger vehicle, a truck, a bus, a motorcycle, and a trolley bus. Examples of the industrial vehicle include an industrial vehicle for agriculture and an industrial vehicle for construction. Examples of the industrial vehicle include a forklift and a golf cart. Examples of the industrial vehicle for agriculture include a tractor, a cultivator, a transplanter, a binder, a combine, and a lawn mower. Examples of the industrial vehicle for construction include a bulldozer, a scraper, a power shovel, a crane vehicle, a dump truck, and a road roller. Examples of the vehicle include a human-powered vehicle. The classification of the vehicle is not limited to the above examples. Examples of the automobile include an industrial vehicle travelling on a road. One type of vehicle may fall within multiple classes. Examples of the vessel include a jet ski, a boat, and a tanker. Examples of the aircraft include a fixed-wing aircraft and a rotary-wing aircraft. In the example described below, the movable body includes a windshield25. The movable body may be any of the above examples including a combiner in place of the windshield25.

The camera50is installed on the movable body. The camera50captures an image of a space expected to include, for example, the face, or the upper body of the driver or a user of the movable body. The camera50may be installed at any position inside or outside the movable body. The camera50may be installed, for example, inside or on a dashboard in the movable body. The camera50may be installed, for example, inside another device such as an air duct.

The camera50may be an infrared camera that receives infrared light and generates images. The camera50may function both as an infrared camera and a visible light camera. The camera50may include, for example, a charge-coupled device (CCD) image sensor or a complementary metal-oxide-semiconductor (CMOS) image sensor.

The camera50outputs a captured image to the controller40. The camera50may output a captured image to the controller40through wired communication or wireless communication. The wired communication may include, for example, communication using a controller area network (CAN). The controller40may detect the position of eyes5of the user based on the captured image output from the camera50. The controller40changes the image to be displayed on the display10based on the detected position of the eyes5of the user.

In the present embodiment, the imaging optical system20B in the aerial image display device1B includes optical elements that are a freeform mirror21and a windshield25. The image light emitted from the display10is reflected from the freeform mirror (concave mirror)21, reaches the windshield25, and is then reflected from the windshield25to reach the eyes5of the user. The user can thus view an aerial image.

In the present embodiment, the drive30can control shifts from the first positioning to the second positioning and from the second positioning to the first positioning by, for example, changing the spatial position of the display10. In the present embodiment, the drive30can move the display10to the first spatial position and to the second spatial position. The movements of the display10in the present embodiment are rotational. In the present embodiment, the position of the freeform mirror21may be fixed. The drive30may have any structure that allows the display10to move between the first spatial position and the second spatial position from one position to the other. Examples of such a structure include an electric slider and an electric cylinder. The drive30may stop the display10at two positions that are the first spatial position and the second spatial position. The drive30may stop the display10at the two positions, or the first spatial position and the second spatial position, or at any position between the first spatial position and the second spatial position.

When the display10is rotated to the first spatial position, the first portion21A of the freeform mirror21reflects image light. The windshield25reflects image light reflected from the first portion21A. The display10is located closer to the freeform mirror21than the first object focal point f1. When the display10is rotated to the second spatial position, the second portion21B of the freeform mirror21reflects image light. The windshield25reflects image light reflected from the second portion21B. The display10is located farther from the freeform mirror21than the second object focal point f2.

The user of the aerial image display device1can view a virtual image V with the image light reflected from the windshield25when the display10is at the first spatial position, and can view a real image R with the image light reflected from the windshield25when the display10is at the second spatial position. In the present embodiment, the aerial image display device1B can thus display a real image R and a virtual image V in the air as the drive30changes the positions of the display10and the optical elements relative to one another.

The controller40may control the drive30based on the position of the eyes5of the user. The controller40may move the display10based on the position of the eyes5of the user to switch the aerial display between a real image R and a virtual image V. The controller40may also control the drive30based on, for example, the operating state (e.g., being stopped or being traveling) of the movable body. The controller40may move the display10based on the operating state of the movable body to switch the aerial display between a real image R and a virtual image V.

In a variation of a tenth embodiment, the display10may be fixed, and the position of the freeform mirror21may be shifted between the first positioning and the second positioning to switch the aerial display between a real image R and a virtual image V.

Upon switching from a real image R to a virtual image V or from a virtual image V to a real image R, the eyes5of the user may fail to respond to the switch. The user may take time before viewing the new image, or feel discomfort from visually induced motion sickness. The controller40may cause, for example, the display10to display a black image when switching the image to be displayed on the display10between an image for display as a real image R and an image for display as a virtual image V. A black image is displayed to reduce the likelihood of the viewability being lowered, and thus reduce discomfort.

The aerial image display device1B may be in other embodiments described below. The camera50may capture an image of the user to obtain an image of the pupils of the eyes5of the user. The controller40may perform control to enlarge the image to be displayed on the display10when the pupils enlarge. When the pupils of the user enlarge, the user gazes at the image or a part of the image. Enlarging the image to be displayed on the display10allows the user to view the image or a part of the image more easily. This allows the user aboard a transport vehicle to avoid unsafe situations more easily. The ratio of enlargement of the image may be, but not limited to, more than one time and about three times or less. A part of the image being gazed at by the user may be detected, and the part of the image being gazed at by the user may be enlarged.

The camera50may capture an image of the user to obtain an image of the pupils of the eyes5of the user. The controller40may perform control to increase the luminance of the image to be displayed on the display10when the pupils enlarge. This produces the same or similar advantageous effects as described above, allowing the user aboard a transport vehicle to avoid unsafe situations more easily. The luminance of the image may be increased by a factor of, but not limited to, more than one and about ten or less. A part of the image being gazed at by the user may be detected, and the luminance may be increased in the part of the image being gazed at by the user.

The camera50may capture an image of the user to obtain an image of the pupils of the eyes5of the user. The controller40may perform control to increase the contrast of the image to be displayed on the display10when the pupils enlarge. This produces the same or similar advantageous effects as described above, allowing the user aboard a transport vehicle to avoid unsafe situations more easily. The contrast of the image may be increased by a factor of, but not limited to, more than one and about two or less. A part of the image being gazed at by the user may be detected and the contrast may be increased in the part of the image being gazed at by the user.

The camera50may capture an image of the user to obtain an image of the pupils of the eyes5of the user. The controller40may perform control to increase the frame frequency of the image to be displayed on the display10when the pupils enlarge. This produces the same or similar advantageous effects as described above, allowing the user aboard a transport vehicle to avoid unsafe situations more easily. The frame frequency of the image may be increased by a factor of, but not limited to, more than one and about eight or less.

In one or more embodiments of the present disclosure, first, second, or others are identifiers for distinguishing the components. The identifiers of the components distinguished with first, second, and others in the present disclosure are interchangeable. For example, the first reflective element is interchangeable with the second reflective element. The identifiers are to be interchanged together. The components for which the identifiers are interchanged are also to be distinguished from one another. The identifiers may be eliminated. The components without such identifiers can be distinguished with reference numerals. The identifiers such as first and second in the present disclosure alone should not be used to determine the order of components or to suggest the existence of smaller number identifiers.

The aerial image display device according to one or more embodiments of the present disclosure may be implemented in forms 1 to 15 described below.

(1) An aerial image display device, comprising:a display configured to display an image with traveling image light;an imaging optical system including one or more optical elements, the imaging optical system being configured to receive the traveling image light as incident light, the imaging optical system having a first object focal point and a second object focal point with a shorter focal length than the first object focal point; anda drive configured to change positional relationship between the first object focal point and the display relative to each other or between the second object focal point and the display relative to each other, the drive being configured to switch between first positioning and second positioning, the first positioning being positioning with the display located closer to the imaging optical system than the first object focal point of the imaging optical system to display a virtual image in air, the second positioning being positioning with the display located farther from the imaging optical system than the second object focal point of the imaging optical system to display a real image in air.

(2) The aerial image display device according to (1), whereinthe imaging optical system is a reflective optical system or a catadioptric optical system.

(3) The aerial image display device according to (2), whereinthe optical element is a freeform mirror, andthe imaging optical system switches between the first object focal point and the second object focal point in response to a position of the freeform mirror on which the traveling image light is incident.

(4) The aerial image display device according to any one of (1) to (3), further comprising:a controller configured to change an image to be displayed on the display.

(5) The aerial image display device according to (4), whereinthe controller switches an up-down orientation of an image to be displayed on the display between an up-down orientation for the first positioning and an up-down orientation for the second positioning.

(6) The aerial image display device according to (4) or (5), whereinthe controller switches a distortion correction table for an image to be displayed on the display between a distortion correction table for the first positioning and a distortion correction table for the second positioning.

(7) The aerial image display device according to (4), whereinthe controller performs control to enlarge an image to be displayed on the display for displaying a virtual image in air relative to an image to be displayed on the display for displaying a real image in air.

(8) The aerial image display device according to (4), whereinthe controller performs control to cause luminance of an image to be displayed on the display for displaying a virtual image in air to be higher than luminance of an image to be displayed on the display for displaying a real image in air.

(9) The aerial image display device according to (4), whereinthe controller performs control to cause a contrast of an image to be displayed on the display for displaying a virtual image in air to be higher than a contrast of an image to be displayed on the display for displaying a real image in air.

(10) The aerial image display device according to (4), whereinthe controller performs control to cause a frame frequency of an image to be displayed on the display for displaying a virtual image in air to be higher than a frame frequency of an image to be displayed on the display for displaying a real image in air.

(11) The aerial image display device according to any one of (1) to (10), further comprising:a camera configured to capture an image of a user,wherein the controller changes an image to be displayed on the display based on a position of an eye of the user.

(12) The aerial image display device according to (11), whereinthe camera captures an image of the user to obtain an image of a pupil of the eye of the user, andthe controller enlarges an image to be displayed on the display when the pupil enlarges.

(13) The aerial image display device according to (11) or (12), whereinthe camera captures an image of the user to obtain an image of a pupil of the eye of the user, andthe controller increases luminance of an image to be displayed on the display when the pupil enlarges.

(14) The aerial image display device according to any one of (11) to (13), whereinthe camera captures an image of the user to obtain an image of a pupil of the eye of the user, andthe controller increases a contrast of an image to be displayed on the display when the pupil enlarges.

(15) The aerial image display device according to any one of (11) to (14), whereinthe camera captures an image of the user to obtain an image of a pupil of the eye of the user, andthe controller increases a frame frequency of an image to be displayed on the display when the pupil enlarges.

The aerial image display device according to one embodiment of the present disclosure can display a real image and a virtual image in the air.

The present disclosure may be embodied in various forms without departing from the spirit or the main features of the present disclosure. The embodiments described above are thus merely illustrative in all respects. The scope of the present disclosure is defined not by the description given above but by the claims. Any variations and alterations contained in the claims fall within the scope of the present disclosure.

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