Head-up display device and vehicle

A head-up display device includes a display element, a beam splitter, a movable mirror, first and second mirrors, and a movable unit. The display element emits light to form a display image. The beam splitter being an optical member that reflects light or through which light is transmitted, reflects light emitted from the display element. The movable mirror reflects light reflected off the beam splitter. The first and second mirrors that reflect light movable mirror, or through which the light transmitted through the beam splitter is transmitted, project a virtual image. The movable unit adjusts a distance between the movable mirror and the beam splitter to adjust a projection distance of the virtual image.

TECHNICAL FIELD

The present disclosure relates to a vehicle display device, and more particularly to a head-up display device used in an automobile or the like.

BACKGROUND

There is known a head-up display device as an information display device of an automobile or the like.

Japanese Laid-Open Patent Publication No. H6-115381 discloses a head-up display device using a concave mirror as a turning mirror that can vary a position of a virtual image by varying a distance between a display as an object point and the concave mirror within a range allowing a virtual image point mirrored by the concave mirror to appear, in a manual manner or an automatic manner, or in a combination of these manners.

Japanese Laid-Open Patent Publication No. 2009-150947 discloses a vehicle head-up display device that includes a light source, a scan unit that scans light from the light source in a two-dimensional manner, a screen on which an image is formed by scanned light, and a projection unit that projects the image on the screen, and that varies a distance between the projection unit and the screen to vary a position of a virtual image projected.

SUMMARY

The present disclosure provides a head-up display device capable of varying a projection distance of a virtual image to be projected at high speed.

A head-up display device in the present disclosure includes a display that emits light to form a display image, a light separator being an optical member that reflects light or through which light is transmitted, and that reflects light emitted from the display, a first optical member that reflects light reflected off the light separator, one or more second optical members that reflect light transmitted through the light separator after being reflected off the first optical member, or through which the light transmitted through the light separator is transmitted, to project a virtual image, and an adjuster that adjusts a distance between the first optical member and the light separator to adjust a projection distance of the virtual image.

According to the present disclosure, a head-up display device capable of varying a projection distance of a virtual image to be projected at high speed can be provided.

DESCRIPTION OF EMBODIMENT

Embodiments of the present invention will be described below while appropriately referring to accompanying drawings. Detailed description more than necessary may be eliminated. For example, detailed description of a well-known matter and duplicated description of substantially identical structure may be eliminated. This allows the description below to avoid becoming unnecessarily lengthy for easy understanding by a person skilled in the art. The inventors provide the accompanying drawings and the description below to allow a person skilled in the art to sufficiently understand the present disclosure, so that there is no intension to limit a subject of the description to the scope of claims.

In all the drawings, an element having a common function is designated by the same reference numeral, and duplicated description on an element that has been described is eliminated.

[1-1-1. Structure of Vehicle]

FIG. 1illustrates an example of a structure of a vehicle provided with a head-up display device in an embodiment of the present disclosure.FIG. 1illustrates a vehicle10that includes a head-up display device1, a navigation device20, and a camera30.

The navigation device20provides information on a route to a predetermined destination to a driver to guide the route. The navigation device20includes a built-in memory in which map information21is stored. The navigation device20also includes a location information acquiring unit22such as a global positioning system (GPS) to acquire location information on the vehicle itself, and stores the information in the built-in memory.

The camera30takes a picture ahead of the vehicle itself, for example, to create image information.

The head-up display device1projects image light on a windshield170of the vehicle to project a virtual image190ahead of the windshield170with respect to driver's eyes180. The head-up display device1sets a projection position of the virtual image190on the basis of location information on the vehicle or map information from the navigation device20, or image information from the camera30.

[1-1-2. Schematic Structure of Head-up Display Device]

FIG. 2is a block diagram illustrating an example of a configuration of the head-up display device1in the embodiment 1 of the present disclosure.

The head-up display device1includes an optical system unit50and a control unit60.

The control unit60is formed of a CPU or an MPU, for example, to execute a program stored in a memory, so that various functions are achieved. The control unit60may be formed of a hardware circuit (e.g. ASIC and FPGA), such as exclusively designed electronic circuit, and an electronic circuit that can be reconfigured. Functions of the control unit60may be achieved by cooperation of hardware and software, or may be achieved by only hardware (electronic circuit).

The control unit60includes a peripheral information acquiring unit61, a vehicle information acquiring unit62, and an optical control unit63.

The peripheral information acquiring unit61detects a peripheral building and scene, and an object on a road surface by analyzing image information ahead of a vehicle from the camera30to acquire information on a distance from the vehicle itself to the building or the object. The object on a road surface is an intersection, for example.

The vehicle information acquiring unit62acquires speed information from various sensors of the vehicle.

The optical control unit63extracts a peripheral building and scene, and an object on a road surface on the basis of map information from the navigation device20. The optical control unit63acquires information on a distance from the vehicle to the building or the object on the basis of location information on the vehicle and map information from the navigation device20. Then, the optical control unit63causes the optical system unit50to project a virtual image190such that the virtual image190is positioned near the building or the object, on the basis of the acquired information on the distance. This enables facility information to be projected near a building or enables route guidance information to be projected near an intersection, as information of the navigation device20, for example.

Alternatively, the optical control unit63may cause the optical system unit50to project a virtual image190such that the virtual image190is positioned near a building or an object on the basis of information on a distance from the vehicle itself to the building or the object from the peripheral information acquiring unit61.

In addition, the optical control unit63may set a projection position of the virtual linage190on the basis of speed information on the vehicle from the vehicle information acquiring unit62. For example, a projection position of the virtual image190may be set such that the virtual image is projected far when a vehicle travels at high speed and a driver's eye point is on a far side, and that the virtual image is projected closely when the vehicle travels at low speed and the driver's eye point is on a near side.

The optical system unit50includes an optical system for projecting a virtual image. The optical system unit50of the head-up display device1will be described below with reference toFIGS. 3 and 4. In the head-up display device1illustrated inFIGS. 3 and 4, only the optical system unit50is illustrated and the control unit60is eliminated (the same applies to embodiments 2 to 8).

[1-1-3. Structure of Head-Up Display Device (Optical System Unit)]

FIG. 3illustrates an example of a structure of the optical system unit50of the head-up display device1in the embodiment 1 of the present disclosure.

The head-up display device1of the embodiment 1 includes a display element110, a beam splitter120serving as a light separator, a movable mirror130, a movable unit140serving as an adjuster, a first mirror150, and a second mirror160. The movable unit140includes a motor141, and a feed screw142. The movable mirror130corresponds to the first optical member, and the first mirror150and the second mirror160correspond to the second optical member.

The display element110is a display that emits light (image light) that forms a display image such as driving information and route information, which are displayed for a driver. The display element110is a liquid crystal display module, for example, and includes a liquid crystal display panel, a liquid crystal display panel drive circuit board, a light guide plate, a lens, a diffuser plate, a backlight, a backlight heat sink, and the like.

The beam splitter120reflects image light emitted from the display element110toward the movable mirror130, and allows the image light incident from the movable mirror130to be transmitted through the beam splitter120.

The movable mirror130reflects image light incident from the beam splitter120toward the beam splitter120. The movable mirror is a plane mirror, for example.

The movable unit140changes a distance between the movable mirror130and the beam splitter120to adjust a projection distance of a virtual image. As illustrated inFIG. 3, the movable unit140allows the movable mirror130to move parallel to itself between a position A and a position B. This movement enables a distance between the movable mirror130and the beam splitter120to be changed. The motor141of the movable unit140is controlled by the control unit60on the basis of a detection signal from each of the various sensors of the vehicle, described above, and operation information output from the navigation device20, for example. The feed screw142is rotationally driven by the motor141. The movable unit140adjusts a distance between the movable mirror130and the beam splitter120by rotating the feed screw142.

The first mirror150reflects image light transmitted through the beam splitter120toward the second mirror160. In the present disclosure, the first mirror150is a plane mirror.

The second mirror160projects image light reflected off the first mirror150, as a virtual image, ahead of the windshield170of the vehicle as viewed from a driver. The second mirror160is a spherical concave mirror, for example, and reflects and condenses image light from the first mirror150to project a virtual image190ahead of driver's eyes180through the windshield170.

Operation of the head-up display device1in the embodiment 1 will be described.

Image light output from the display element110is reflected off the beam splitter120, and is incident into the movable mirror130. The movable mirror130reflects the incident image light. The reflected image light is incident into the beam splitter120again to be transmitted through the beam splitter120.

The image light transmitted through the beam splitter120is reflected off the first mirror150, and then is condensed by the second mirror160. The image light condensed by the second mirror160is reflected off the windshield170to reach the driver's eyes180.

The driver's eyes180visually identify an image or a picture from the display element110far ahead of the windshield170as a virtual image190.

A distance from the driver's eyes180to the virtual image190(hereinafter referred to as a virtual image distance) can be changed when the movable unit140allows the movable mirror130to move parallel to itself between the position A and the position B to adjust a distance between the movable mirror130and the beam splitter120, and thus the distance can be changed between the virtual image190and a virtual image191, for example.

An interval between the movable mirror130and the beam splitter120is set by the control unit60described above on the basis of location information on the vehicle, map information, and virtual image190can be visually identified in a front scene, for example.

The interval between the movable mirror130and the beam splitter120may be set by the control unit60on the basis of information from various sensors of the vehicle and vehicle speed information. For example, the interval between the movable mirror130and the beam splitter120is set such that the virtual image is projected far when the vehicle travels at high speed and a driver's eye point is on a far side, and that the virtual image is projected closely when the vehicle travels at low speed and the driver's eye point is on a near side. This enables movement of a driver's eye point to be reduced.

[1-2-2. Adjustment of Virtual Image Distance]

FIG. 4illustrates a relationship between the amount of movement of the movable mirror120and a virtual image distance.

InFIG. 4, a distance from the display element110to the second mirror160, through which image light is transmitted, is designated as “a”. As illustrated inFIG. 4, when a distance from the display element110to the beam splitter120is designated as “a1”, a distance from the beam splitter120to the movable mirror130is designated as “d”, a distance from the beam splitter120to the first mirror150is designated as “a2”, and a distance from the first mirror150to the second mirror160is designated as “a3”, “a” is expressed by Expression 1.
a=a1+a2+2d+a3[Expression 1]

In addition, a distance from the second mirror160to the virtual image190, through which image light is transmitted, is designated as “b”. As illustrated inFIG. 4, when a distance from the second mirror160to the windshield170is designated as “b2”, and a distance from the windshield170to the virtual image190is designated as “b1”, “b” is expressed by Expression 2.
b=b1+b2[Expression 2]

When a curvature radius of the second mirror160is designated as “R”, the distances “a” and “b”, and “R” have a relationship expressed by Expression 3.

Where “a” and “b” each are an absolute value, a sigh of 1/b is negative to satisfy a virtual image display condition.

In addition, when a distance from the driver's eyes180to the windshield170is designated as “b3”, a virtual image distance “L” from the driver's eyes180to the virtual image190is expressed by Expression 4.
L=b1+b3[Expression 4]

The curvature radius R of the second mirror160is a fixed value, so that increase in the distance “d” increases the distance “a” and the distance “b” according to Expressions 1 to 3.

Thus, when the distance “b3” from the driver's eyes180to the windshield170is constant, increase in the distance “d” increases the virtual image distance “L”.

Specifically, when the movable mirror130is shifted from the position A to the position B, for example, a distance between the movable mirror130and the beam splitter120increases to increase the distance “d”, and thus the virtual image190moves to the virtual image191.

Image light travels back and forth once between the beam splitter120and the movable mirror130. Thus, when the distance “d” is changed by “d1”, for example, the distance “a” increases by twice “d1” according to Expression 1.

As described above, the movable mirror130being a movable body is disposed in a space where image light travels back and forth, so that moving the movable mirror130by only one-half of a desired variation of the distance “a” enables a target change in virtual image distance to be acquired. This enables reduction in the entire size of the head-up display device1.

As a specific example, there is considered an optical system of a head-up display in which a virtual image distance can be changed within a range from 2 m to 100 m, for example.

In contrast, when the same variable range of a virtual image distance as that ofFIG. 4is achieved in a conventional head-up display device in which a display is movable, a moving range of a display is twice “d1”, or 59 mm.

According to a structure of the embodiment 1, a moving range of a movable unit140can be reduced by approximately 30 mm as compared with a conventional structure. This enables providing a head-up display device with a small-sized structure.

In the present embodiment, the second mirror160is a spherical mirror, and the first mirror150is a plane mirror. However, the present disclosure is not limited to the above mirrors, and each or the mirrors may be a spherical concave mirror, a spherical convex mirror, a non-spherical concave mirror, a non-spherical convex mirror, or a free-form surface mirror.

As described above, in the present embodiment, the head-up display device1includes the display element110, the beam splitter120, the movable mirror130, the first and second mirrors150and160, and the movable unit140. The display element110emits image light to form a display image. The beam splitter120is an element that reflects image light or allows image light to be transmitted through the element, and reflects image light emitted from the display element110. The movable mirror130reflects image light reflected off the beam splitter120. The first and second mirrors150and160each reflect image light transmitted through the beam splitter120after reflected off the movable mirror130to project the virtual image190. The movable unit140adjusts a distance between the movable mirror130and the beam splitter120to adjust a projection distance of the virtual image190.

In the head-up display device1, the image light emitted from the display element110is reflected off the beam splitter120, reflected off the movable mirror130and incident into the beam splitter120again. The image light incident into the beam splitter120is transmitted through the beam splitter120to be reflected off the first mirror150, and then is condensed by the second mirror160. The condensed image light is reflected off the windshield170to reach the driver's eyes180. The movable unit140changes a distance between the movable mirror130and the beam splitter120to adjust a projection distance of a virtual image. This allows the movable unit140to shift the movable mirror130, so that a virtual image existance can be changed.

Conventionally, there is known a head-up display device that adjusts a position of a display element to adjust a projection distance of a virtual image. The display element has a high heating value, so that a heat sink needs to be provided, and thus is heavy. Thus, it is difficult to move the display element at high speed. As a result, it is difficult to change a projection distance of the virtual image190at high speed.

In contrast, in the present embodiment, the movable mirror130lighter than the display element110provided with a heat sink is moved, so that the movable mirror130can be moved at relatively nigh speed. Thus, a projection distance of the virtual image190can be changed at relatively high speed.

The movable mirror130being a movable body is disposed in a space where image light travels back and forth, so that a moving range of a movable unit can be reduced as compared with a conventional structure. This enables providing a head-up display device with a small-sized structure.

The movable mirror130is positioned near the display element110. That is, the movable mirror130is disposed in a region where a beam of light from the display element110is relatively small in width. Thus, the movable mirror130is relatively small in width and light in weight as compared with the second mirror160and the first mirror150. As a result, a less load is applied to the movable unit140when the movable mirror130is shifted, so that the movable mirror130can be moved at high speed to quickly change a virtual image distance.

This enables providing a head-up display device with a small-sized structure, capable of changing a projection display distance of a virtual image at high speed.

In the present embodiment, the second mirror160is a spherical mirror, and the first mirror150is a plane mirror. However, the present disclosure is not limited to the above mirrors, and each of the mirrors may be a spherical concave mirror, a spherical convex mirror, a non-spherical concave mirror, a non-spherical convex mirror, or a free-form surface mirror.

This enables an aberration of an optical system to be corrected by the less number of mirrors, so that a head-up display device with a small-sized structure can be provided.

The movable unit140adjusts a distance between the movable mirror130and the beam splitter120according to location information on the vehicle to adjust a projection distance of a virtual image. This enables providing a head-up display device capable of projecting a virtual image on a peripheral building and scene, or a road surface, in coordination with the location information on the vehicle and information from the navigation device, for example.

The movable unit140also adjusts a projection distance of a virtual image according to travel information on the vehicle. Accordingly, for example, when a vehicle travels at high speed and a driver's eye point is on a far side, a virtual image can be projected far. When the vehicle travels at low speed and the driver's eye point is on a near side, the virtual image can be projected closely. This enables providing a head-up display device with high visibility, causing less movement of a driver's eye point.

FIG. 5illustrates an example of a structure of a head-up display device2in an embodiment 2 of the present disclosure. InFIG. 5, the component same as that ofFIG. 3, as well as a component performing the same operation as that ofFIG. 3is designated as the same reference numeral to eliminate duplicated description.

Unlike the structure ofFIG. 3, the structure ofFIG. 5includes an image processing unit210for adjusting an image or a picture to be displayed in a display element110.

The image processing unit210adjusts display magnification of an image or a picture to be displayed in the display element110in synchronization with a virtual image distance signal received from a control unit60, and outputs the image or the picture to the display element110. The image processing unit210may be fabricated in the control unit60described above, or may be fabricated along with the control unit60.

In the structure of the embodiment 1, a magnification M of a virtual image projected, against an image or a picture in the display element110, can be acquired by Expression 5 according to Expressions 2 to 4.

Where R, b2, and b3are constant, the magnification M of a virtual image projected changes in proportion to a virtual image distance L and 2/R.

Thus, Expression 5 expresses a field angle of a virtual image visually identified by a driver that changes in accordance with change in the virtual image distance L. That is, Expression 5 expresses a virtual image at any distance as viewed from a driver that changes in apparent size in accordance with change in the virtual image distance L.

In an actual head-up display device, there is a problem in which a spherical mirror160is relatively large in size, so that large distortion may be caused in a virtual image visually identified by a driver when a virtual image distance is changed. That is, there is a problem of causing distortion aberration.

The distortion aberration distorts a virtual image to cause a substantial size of the virtual image to enlarge or contract, so that the virtual image is further changed in apparent size when a virtual image distance is changed.

From the point described above, there is a problem in which a virtual image changes in apparent size when a virtual image distance is changed while the same image or picture is visually identified, so that it becomes difficult to visually identify the virtual image.

The structure ofFIG. 5solves the problems described above. The head-up display device2receives a virtual image distance signal in synchronization with location information on the movable mirror130, and the image processing unit210enlarges or contracts an image to be displayed in the display element110in accordance with a virtual image distance indicated, by the virtual image distance signal. The virtual image distance signal is created by the control unit60on the basis of the amount of movement of the movable mirror130, or the amount of adjustment of a projection distance of the virtual image. This enables a size of the virtual image at any distance as viewed from a driver to be constant even if the virtual image distance changes.

The aforementioned distortion of a virtual image, caused by change in a virtual image distance, can be corrected by intentionally distorting an image to be displayed in the display element110in a direction opposite to the distortion of the virtual image in accordance with the amount of correction that is previously acquired. Thus, when the image processing unit210distorts an image to be displayed in the display element110through the signal, a shape of a virtual image at any distance as viewed from a driver can be constant, and thus distortion of a virtual image projected can be reduced.

Other structure and operation are similar to those of the embodiment 1, so that detailed description thereof is eliminated.

In the head-up display device2of the embodiment 2, the image processing unit210adjusts display magnification of a display image in accordance with a projection distance of a virtual image.

This enables change of a virtual image in size when a projection distance of the virtual image is changed to be corrected through image processing, for example, so that it is possible to provide a head-up display device that displays a virtual image with high visibility.

In the head-up display device2of the embodiment 2, the image processing unit210also corrects image distortion of a display image in accordance with a projection distance of a virtual image.

This enables distortion of a virtual image when a projection distance of the virtual image is changed to be corrected through image processing, for example, so that it is possible to provide a head-up display device that displays a virtual image with high visibility.

In the present embodiment, the image processing unit210adjusts display magnification of a display image such that a virtual image is constant in size even if a virtual image distance is changed. However, the image processing unit210may adjust display magnification of a display linage such that a virtual image is changed in size in accordance with a virtual image distance. For example, the image processing unit210enlarges or contracts an image to be displayed in the display element110such that a virtual image decreases in size when a virtual image distance is long and the virtual image increases in size when the virtual image distance is short. As described above, visibility of a virtual image can be increased by using perspective instead of allowing the virtual image to be constant in size.

FIG. 6illustrates an example of a structure of an optical system unit50of a head-up display device3in an embodiment 3 of the present disclosure.

The head-up display device3of the embodiment 3 includes a display element111, a reflection-type polarization beam splitter121serving as a light separator, a movable mirror130, a movable unit140, a first mirror150, a second mirror160, and a quarter-wave plate310. InFIG. 6, the component same as that ofFIG. 3, as well as a component performing the same operation as that ofFIG. 3is designated as the same reference numeral to eliminate duplicated description.

In the present embodiment 3, linear polarization light in a polarization direction parallel to an incident surface of the reflection type polarization beam splitter121is indicated as p-polarization light, and linear polarization light in a polarization direction perpendicular to the incident surface thereof is indicated as s-polarization light. Thus, inFIG. 6, a polarization direction of the p-polarization light is parallel to the paper-surface, and a polarization direction of the s-polarization light is perpendicular to the paper-surface. InFIG. 6, the display element111is a liquid crystal element that emits p-polarization light, for example.

The reflection type polarization beam splitter121reflects image light incident from the display element111toward the movable mirror130, and allows the image light incident from the movable mirror130to be transmitted through the reflection type polarization beam splitter121.

The reflection type polarization beam splitter121uses a wire grid polarizing film on which a fine periodic structure of aluminum is formed, for example. As the wavelength plate, a phase difference film, a crystal wavelength plate, and the like are available. The reflection type polarization beam splitter121is disposed in a direction allowing p-polarization light to be reflected and s-polarization light to be transmitted therethrough.

The quarter-wave plate310is disposed such that a polarization direction of light incident from the display element111is to be an azimuth angle of 45 degrees to a high speed axis (or a low speed axis) of the quarter-wave plate310. The quarter-wave plate310is configured to control polarization of light from the display element111to increase utilization efficiency of the light from the display element111.

Operation of the head-up display device3in the embodiment 3 will be described below with reference toFIG. 6.

Image light emitted from the display element111is reflected off the reflection type polarization beam splitter121, and is converted into circular polarization light by being transmitted through the quarter-wave plate310, and then is totally reflected off the movable mirror130. The light reflected off the movable mirror130is incident into the quarter-wave plate310again, and is transmitted through the quarter-wave plate310. This allows the transmitted light (image light) to be converted into light having a component of s-polarization. After that, the light transmitted through the reflection type polarization beam splitter121is reflected off the first mirror150to be condensed by the second mirror160, and then is reflected off a windshield170to reach driver's eyes180.

When an unpolarized beam splitter with an equal split ratio is used as the reflection type polarization beam splitter121, for example, the amount of reflected light as well as the amount of transmitted light becomes about half and another half is lost when light is reflected off and transmitted through the beam splitter. However, when the reflection type polarization beam splitter121and the quarter-wave plate310are used to control polarization of light from the display element111as with the structure ofFIG. 6, it is possible to greatly reduce loss of light.

Other structure and operation are similar to those of the embodiment 1, so that detailed description thereof is eliminated.

[3-3. Example of Another Structure]

Each of a polarization direction in the display element111, one on a reflection side of the reflection type polarization beam splitter121, and one on a transmitting side thereof, is not limited to only that described above. When light from the display element111is indicated as s-polarization light, for example, the reflection type polarization beam splitter121also can be disposed in a direction allowing the s-polarization light to be reflected and the p-polarization light to the transmitted therethrough. An example of this case will be described with reference toFIG. 7.

FIG. 7illustrates an example of another structure of an optical system unit50of a head-up display device4in the embodiment 3 of the present disclosure.

The head-up display device4includes a display element112, a reflection type polarization beam splitter122serving as a light separator, a movable mirror130, a movable unit140, a first mirror150, a second mirror160, a first quarter-wave plate410, and a second quarter-wave plate420. InFIG. 7, the component same as that of each ofFIGS. 3 and 6is designated as the same reference numeral to eliminate duplicated description.

The display element112uses a liquid crystal element that emits s-polarization light, and the reflection type polarization beam splitter122is disposed in a direction allowing the s-polarization light to be transmitted and the p-polarization light to be reflected.

Each of the first quarter-wave plate410and the second quarter-wave plate420is disposed such that a polarization direction of light incident from the display element111is to be an azimuth angle of 45 degrees to a high speed axis (or a low speed axis) of each of the first quarter-wave plate410and the second quarter-wave plate420.

As illustrated inFIG. 7, image light including an image or a picture displayed in the display element is converted into circular polarization light by being transmitted through the first quarter-wave plate410, and is converted into p-polarization light by being transmitted through the second quarter-wave plate420.

The light transmitted through the second quarter-wave plate420is reflected off the reflection type polarization beam splitter122, and then is transmitted through the second quarter-wave plate420again to be converted into circular polarization light.

The light converted into circular polarization light is totally reflected off the movable mirror130, and is transmitted through the second quarter-wave plate420again to be converted into s-polarization light, and then is transmitted through the reflection type polarization beam splitter122.

The light transmitted through the reflection type polarization beam splitter122is reflected off the first mirror150, and is further condensed by the second mirror160. The condensed light is reflected off a windshield170to reach driver's eyes180.

The head-up display device3of the embodiment 3 includes the light separator121that is a wire grid polarizer, and the quarter-wave plate310.

The head-up display device4includes the light separator122that is a wire grid polarizer, the first quarter-wave plate410, and the second quarter-wave plate420.

This enables loss of light in a light separator to be reduced, so that a bright head-up display device with high visibility can be provided.

FIG. 8illustrates an example of a structure of an optical system unit50of a head-up display device5in an embodiment 4 of the present disclosure. InFIG. 8, the component same as that ofFIG. 3is designated as the same reference numeral to eliminate duplicated description.

Unlike the structure ofFIG. 3, the structure ofFIG. 8is configured to eliminate a first mirror150to further reduce a size of the entire optical system.

InFIG. 8, image light including an image or a picture, displayed in a display element110, is reflected off a beam splitter120, and is further reflected off a movable mirror130, and then is transmitted through the beam splitter120. The image light transmitted through the beam splitter120is condensed by a second mirror160, and is reflected off a windshield170of a vehicle to reach driver's eyes180. The driver's eyes180visually identify an image or a picture displayed in the display element110far ahead of the windshield170as a virtual image190.

As with the embodiment 3, a reflection type polarization beam splitter may be used as the beam splitter120and a quarter-wave plate may be disposed between the beam splitter120and the movable mirror130to increase utilization efficiency of light from the display element110.

Other structure and operation are similar to those of the embodiment 1, so that detailed description thereof is eliminated.

FIG. 9illustrates an example of a structure of an optical system unit50of a head-up display device6in an embodiment 5 of the present disclosure.

Unlike the structure ofFIG. 3, the structure ofFIG. 9is configured to provide a combiner mirror161separately from a windshield so that the combiner mirror161reflects an image or a picture displayed in a display element110to project the image or the picture far ahead of the combiner mirror161as a virtual image.

InFIG. 9, image light including an image or a picture, displayed in the display element110, is reflected off a beam splitter120, and is further reflected off a movable mirror130, and then is transmitted through the beam splitter120.

The image light transmitted through the beam splitter120is reflected off a first mirror150, and is reflected off and condensed by the combiner mirror161to reach driver's eyes.

The driver's eyes180visually identify an image or a picture displayed in the display element110far ahead of the combiner mirror161as a virtual image190.

Other structure and operation are similar to those of the embodiment 1, so that detailed description thereof is eliminated.

FIG. 10illustrates an example of a structure of an optical system unit50of a head-up display device7in an embodiment 6 of the present disclosure.

InFIG. 10, the component same as that ofFIG. 3is description. Unlike the structure ofFIG. 3, the structure ofFIG. 10is configured to use a laser projector that scans a laser beam for projection display on a screen, as a display element.

The head-up display device7includes a laser beam source710, a scan unit720, and a screen730, instead of the display element110of the head-up display device1.

The laser beam source710includes three laser elements of red, blue, and green, for example. The scan unit720scans a beam from the laser beam source710by deflecting the beam in a two-dimensional manner.

For the screen730, a Fresnel screen, a diffusing screen, a screen formed by combining a Fresnel lens and a diffuser plate, or the like is used.

InFIG. 10, light emitted from the laser beam source710is scanned on the screen730in a two-dimensional manner by the scan unit720, so that an image or a picture is displayed on the screen730. Image light including the image or the picture on the screen730is reflected off a beam splitter120, and is further reflected off a movable mirror130, and then is transmitted through the beam splitter120.

The image light transmitted through the beam splitter120is reflected off a first mirror150and is reflected off and condensed by a second mirror160. The condensed image light reaches driver's eyes180after being reflected off a windshield170.

The driver's eyes180visually identify the image or the picture displayed on the screen730far ahead of the windshield170as a virtual image190.

As withFIG. 3, when the movable mirror130is moved to change a virtual image distance in the structure ofFIG. 10, a field angle of a virtual image is changed, as described in the embodiment 2.

Unlike the embodiment 2, a field angle can be maintained constant by changing a deflection angle of the scan unit720in accordance with a virtual image distance in the present embodiment 6.

Using laser elements of three respective colors of red, blue, and green enables a full-color virtual image to be displayed. Besides this, in the present disclosure, a laser element for one color, two colors, or four colors or more, is available.

Other structure and operation are similar to those of the embodiment 1, so that detailed description thereof is eliminated.

The head-up display device7of the embodiment 6 includes the scan unit720that scans light emitted from a plurality of laser beam sources710, and the screen730on which scanned light from the scan unit720forms an image.

This enables providing a head-up display device with a bright display screen because a laser beam source has high luminance, for example.

FIG. 11illustrates an example of a structure of an optical system unit50of a head-up display device8in an embodiment 7 of the present disclosure.

The head-up display device8illustrated inFIG. 11further includes a reflection mirror810in addition to the structure ofFIG. 3. That is, in the head-up display device8of the present embodiment, an optical system that displays two virtual images each having a different virtual image distance is disposed in one device. A position of the reflection mirror810is fixed.

As withFIG. 3, in the structure illustrated inFIG. 11, first image light including an image or a picture displayed in some regions of a display element110is reflected off a beam splitter120and a movable mirror130, or is transmitted therethrough, to be reflected off a first mirror150, and then is condensed by a second mirror160. After that, the condensed first image light is reflected off a windshield170of a vehicle to reach driver's eyes180.

The driver's eyes180visually identify the first image light displayed in the display element110far ahead of the windshield170as a virtual image190.

In addition, second image light including an image or a picture, displayed in another region of the display element110, is reflected off the beam splitter120, and is further reflected off the reflection mirror810, and then is transmitted through the beam splitter120.

The second image light transmitted through the beam splitter120is reflected off the first mirror150to be condensed by the second mirror160, and then is reflected off the windshield170to reach the driver's eyes180.

The driver's eyes180visually identify the second image light far ahead of the windshield170as a second virtual image193.

In this case, a virtual image distance of the first virtual image190can be changed by adjusting a distance between the movable mirror130and the beam splitter120. Then, a virtual image distance of the second virtual image193is constant without being affected by adjustment of a distance between the movable mirror130and the beam splitter120.

Accordingly, information to be displayed at any virtual image distance in a front scene can be displayed as the first virtual image, and information such as speed and warning, which is unnecessary to be superimposed on the front scene, can be always disposed at a fixed virtual image distance as the second virtual image. As described above, a head-up display device capable of displaying two screens can be fabricated.

In the present embodiment, the number of display elements110and a position of the reflection mirror810are not limited to only those in the structure ofFIG. 11. For example, a plurality of display elements110may be provided, and virtual images may be formed at a plurality of respective different distances. In addition, a part of the beam splitter120can be used instead of the reflection mirror810.

Other structure and operation are similar to those of the embodiment 1, so that detailed description thereof is eliminated.

In the head-up display device8of the embodiment 7, light emitted from the display element110is reflected off the beam splitter120, and the light reflected off the beam splitter120is then reflected off the movable mirror130and the reflection mirror810. The light reflected off the movable mirror130and the light reflected off the reflection mirror810each are transmitted through the beam splitter120, and are reflected off the first mirror150to be condensed by the second mirror160, and then are reflected off the windshield170of a vehicle to reach the driver's eyes180. This allows the two virtual images190and193to be projected ahead of the driver's eyes180through the windshield170. A display position of the virtual image190can be moved by the movable unit140.

Accordingly, information to be displayed at any virtual image distance in a front scene can be displayed as the first virtual image, and information such as speed and warning, which is unnecessary to be superimposed on the front scene, can be always disposed at a fixed virtual image distance as the second virtual image, for example. As described above, a head-up display device capable of displaying two screens can be provided.

The reflection mirror810may be changed in position independently of the movable mirror130. This enables a position of the virtual image193to be changed independently of a position of the virtual image190.

FIG. 12illustrates an example of a structure of an optical system unit50of a head-up display device9in an embodiment 8 of the present disclosure. InFIG. 12, the component same as that ofFIG. 3is designated as the same reference numeral to eliminate duplicated description.

In the embodiment 1 illustrated inFIG. 3, a plane mirror is used as the first mirror150in the second optical member. The present embodiment illustrated inFIG. 12has a structure in which a spherical lens950is used as the second optical member, instead of the first mirror150, so that the structure is different from that of the embodiment 1.

Instead of the spherical lens950, an aspherical lens, a free-form surface lens, or the like may be used.

In addition, instead of the second mirror160in the second optical member, a spherical lens, an aspherical lens, a free-form surface lens, or the lime may be used.

Consequently, a projection optical system can be formed by using a lens instead of the reflection mirror without bending an optical path, for example, so that a head-up display device with a small-sized structure can be provided.

Also in the embodiments 2 to 7, a spherical lens, an aspherical lens, a free-form surface lens, or the like may be used instead of the mirror as the second optical member.

As described above, the embodiments 1 to 8 each are described as an example of the art disclosed in the present application. However, the art in the present disclosure is not limited to the embodiments, and is also applicable to an embodiment in which modification, substitute, addition, elimination, or the like is appropriately made to the embodiments. In addition, the components described in the embodiments 1 to 8 can be combined with each other to form an additional embodiment.

The embodiments each are described as an example of the art in the present disclosure. For that, the accompanying drawings and the detailed description are provided.

Accordingly, the components described in the accompanying drawings and the detailed description may include not only an essential component to solve the problem, but also a component that is unnecessary to solve the problem and is described for description of the art. Thus, description of the unnecessary component in the accompanying drawings and the detailed description does not allow the unnecessary component to be directly acknowledged to be essential.

In addition, the embodiments each described above show the art in the present disclosure, for example, so that various modifications, substitute, addition, elimination, or the like can be made within the scope of claims or its equivalent scope.

INDUSTRIAL APPLICABILITY

The head-up display device according to the present disclosure is applicable to a head-up display device in not only a vehicle, but also an aircraft, an electric train, a vessel, a specific vehicle, and the like.