Patent Publication Number: US-2022219533-A1

Title: Vehicle display device

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     The present application claims priority to and incorporates by reference the entire contents of Japanese Patent Application No. 2021-002499 filed in Japan on Jan. 12, 2021. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a vehicle display device. 
     2. Description of the Related Art 
     Conventionally, some vehicles have been mounted with a vehicle display device configured to virtually display information to be provided to an occupant in a cabin. The vehicle display device is what is called a head-up display device including a displaying part configured to emit display light to provide display information to be projected on a projection target part and a reflection member configured to reflect the display light emitted from the displaying part to project the display light on the projection target part. The vehicle display device allows the occupant to view and recognize, as a virtual image, the display information corresponding to the display light projected on the projection target part. Such a vehicle display device is disclosed in Japanese Patent Application Laid-open No. 2017-9864, for example. 
     By the way, a position of the eyes of an occupant (what is called an eye point), to whom such display information is to be provided, differs depending on a seating height of the occupant and a height of a seating face of a seat, for example. Therefore, the vehicle display device needs to provide clear virtual image display regardless of the eye point in order to enhance the convenience for the occupant. However, in such a vehicle display device, it has not been desired to take such a measure that leads to an increase in power consumption, for example, by increasing the output of emission light of a light source even in order to provide clear virtual image display at such an eye point that varies. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a vehicle display device making it possible to suppress power consumption from increasing, and to provide clear virtual image display in accordance with the eye point. 
     To achieve the above objection, a vehicle display device according to one aspect of the present invention includes a displaying part configured to emit, as display light, display information to be viewed and recognized by an occupant in a cabin as a virtual image; a reflection member configured to reflect the display light emitted from the displaying part to project the display light on a projection target part in the cabin; and a controller configured to control the display light in accordance with a detection eye point representing a detection result of an eye point of the occupant or a detection eye box representing a detection result of an eye box representing a range of the eye point, the eye box allowing the virtual image to be viewed and recognized, wherein the controller controls the displaying part to adjust an emission angle of the display light from the displaying part toward the reflection member in accordance with the detection eye point or the detection eye box to project the display light reflected by the reflection member at a viewpoint position corresponding to the detection eye point or the detection eye box on the projection target part. 
     The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view illustrating a vehicle display device according to an embodiment and first and second modification examples, illustrating a control form with a first eye box disposed at a reference position; 
         FIG. 2  is a schematic view illustrating a displaying part according to the present embodiment, illustrating the control form with the first eye box disposed at the reference position; 
         FIG. 3  is a perspective view illustrating the arrangement of a plurality of light sources according to the present embodiment; 
         FIG. 4  is a schematic view illustrating the vehicle display device according to the present embodiment and the first and second modification examples, illustrating a control form with a second eye box disposed closer to an upper of a vehicle; 
         FIG. 5  is a schematic view illustrating the displaying part according to the present embodiment, illustrating the control form with the second eye box disposed closer to the upper of the vehicle; 
         FIG. 6  is a schematic view illustrating the vehicle display device according to the present embodiment and the first and second modification examples, illustrating a control form with a third eye box disposed closer to a lower of the vehicle; 
         FIG. 7  is a schematic view illustrating the displaying part according to the present embodiment, illustrating the control form with the third eye box disposed closer to the lower of the vehicle; 
         FIG. 8  is a view illustrating a modification form of lighting control for the light sources in the vehicle display device according to the present embodiment; 
         FIG. 9  is a schematic view illustrating a displaying part according to the first modification example, illustrating the control form with the first eye box disposed at the reference position; 
         FIG. 10  is a schematic view when a driving part according to the first modification example is viewed from above the vehicle; 
         FIG. 11  is a schematic view when the driving part according to the first modification example is viewed from a side of the vehicle; 
         FIG. 12  is a schematic view illustrating the displaying part according to the first modification example, illustrating the control form with the second eye box disposed closer to the upper of the vehicle; 
         FIG. 13  is a schematic view illustrating the displaying part according to the first modification example, illustrating the control form with the third eye box disposed closer to the lower of the vehicle; 
         FIG. 14  is a schematic view illustrating a displaying part according to the second modification example, illustrating the control form with the first eye box disposed at the reference position; 
         FIG. 15  is a schematic view when a driving part according to the second modification example is viewed from above the vehicle; 
         FIG. 16  is a schematic view when the driving part according to the second modification example is viewed from the side of the vehicle; 
         FIG. 17  is a schematic view when another form of the driving part according to the second modification example is viewed from above the vehicle; 
         FIG. 18  is a schematic view when the other form of the driving part according to the second modification example is viewed from the side of the vehicle; 
         FIG. 19  is a schematic view illustrating the displaying part according to the second modification example, illustrating the control form with the second eye box disposed closer to the upper of the vehicle; and 
         FIG. 20  is a schematic view illustrating the displaying part according to the second modification example, illustrating the control form with the third eye box disposed closer to the lower of the vehicle. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An embodiment of a vehicle display device according to the present invention will now be described in detail with reference to the accompanying drawings. Note that the present embodiment does not intend to limit the present invention. 
     The reference numeral  1  in  FIG. 1  indicates the vehicle display device according to the present embodiment. Furthermore, the reference numeral  2  in  FIG. 1  indicates a vehicle display device according to a first modification example. Furthermore, the reference numeral  3  in  FIG. 1  indicates a vehicle display device according to a second modification example. The vehicle display devices  1 ,  2 ,  3  are what are called head-up display devices each configured to virtually display information to be provided to an occupant in a cabin of a vehicle (e.g., a motor vehicle). In addition, the vehicle display devices  1 ,  2 ,  3  illustrated in here are exemplified as head-up display devices utilizing what is called the augmented reality (AR) technology that display in an overlapped manner virtual image display information onto actual visual information that the occupant is viewing and recognizing. 
     The vehicle display devices  1 ,  2 ,  3  each include a displaying part  10  configured to emit, as display light, display information to be viewed and recognized by the occupant in the cabin as a virtual image ( FIG. 1 ). The displaying part  10  includes a back light unit  20  and a display unit  30 , and allows light to be emitted from the back light unit  20  toward the display unit  30 , and allows display light representing display information corresponding to incident light from the back light unit  20  to be emitted from the display unit  30 . Furthermore, the vehicle display devices  1 ,  2 ,  3  each include a reflection member  40  configured to reflect the display light emitted from the displaying part  10  (the display unit  30 ) to project the display light on a projection target part Rwf in the cabin ( FIG. 1 ). The reflection member  40  is, for example, a magnifying mirror configured to enlarge and reflect the display light emitted from the displaying part  10 . As the reflection member  40 , for example, an aspheric (free form surface) mirror is used. Furthermore, the vehicle display devices  1 ,  2 ,  3  each include a controller  50  configured to perform display control for the display information ( FIG. 1 ). 
     The vehicle display devices  1 ,  2 ,  3  each further include a housing  61  accommodating the displaying part  10 , the reflection member  40 , and the controller  50  and a cover  62  that is transparent and that covers an opening of the housing  61  ( FIG. 1 ). In the vehicle display devices  1 ,  2 ,  3 , the display light reflected by the reflection member  40  is emitted toward outside the housing  61  from the cover  62 , and is projected on the projection target part Rwf that lies ahead of the housing. The vehicle display devices  1 ,  2 ,  3  illustrated in here are each accommodated in an instrument panel Pi in the cabin with the cover  62  exposed to project the display light reflected by the reflection member  40  on a reflection part, which serves as the projection target part Rwf, of a front windshield Wf ( FIG. 1 ). In the reflection part (the projection target part Rwf) of the front windshield Wf, for example, a semi-transparent coating that partially reflects entered light and allows the rest of the entered light to pass through is applied on a wall surface, inside the cabin, of the front windshield Wf or such a semi-transparent film material is embedded in the front windshield Wf. 
     The display light projected on the projection target part Rwf is emitted from the projection target part Rwf and reflected by one of a plurality of eye boxes EB, and then viewed and recognized by the occupant as a virtual image ( FIG. 1 ). The eye boxes EB respectively represent ranges of a plurality of eye points at which it is possible to view and recognize a virtual image. The eye points respectively represent positions of the eyes of the occupant in the cabin. Therefore, the eye points differ depending on a seating height of the occupant or a height of a seating face of a seat, for example. Therefore, in the vehicle display devices  1 ,  2 ,  3 , the eye boxes EB are set in the cabin. In here, an eye box (hereinafter referred to as a “first eye box”.) EB 1  disposed at a reference position, an eye box (hereinafter referred to as a “second eye box”.) EB 2  disposed closer to an upper of the vehicle than the first eye box EB 1 , and an eye box (hereinafter referred to as a “third eye box”.) EB 3  disposed closer to a lower of the vehicle than the first eye box EB 1  are set ( FIG. 1 ). Note that the eye boxes EB may be arranged in vehicle width directions. 
     Embodiment 
     The vehicle display device  1  according to the present embodiment will first be described herein. 
     In the vehicle display device  1  according to the present embodiment, the displaying part  10  including the back light unit  20  and the display unit  30  is configured as a displaying part  10 A including a back light unit  20 A and a display unit  30 A, as described below ( FIG. 2 ). 
     The back light unit  20 A according to the present embodiment includes a substrate  21 , a plurality of light sources  22 , a plurality of collecting lenses  23 , a field lens  24 , and a diffusion member  25  ( FIG. 2 ). In the back light unit  20 A, the collecting lenses  23  collect emission light from the light sources  22 . The emission light from the collecting lenses  23  then enters the field lens  24 . In the back light unit  20 A, the field lens  24  refracts the incident light. Emission light aligned in an advancing direction by the field lens  24  enters the diffusion member  25 . The diffusion member  25  diffuses the incident light at a wide angle preferable for the display unit  30 A. The diffused light is then emitted toward the display unit  30 A. 
     The substrate  21  is a member for fixing the light sources  22 . The substrate  21  is formed into a rectangular flat plate shape. The light sources  22  are fixed to one plane ( FIGS. 2 and 3 ). 
     The back light unit  20 A is provided, to respectively correspond to the eye boxes EB, with the light sources  22  respectively allowing display light at emission angles corresponding to the eye boxes EB to be emitted from the display unit  30 A ( FIGS. 2 and 3 ). The displaying part  10 A exemplified in here is disposed closer to a rear of the vehicle than the reflection member  40  to emit display light toward the reflection member  40  disposed closer to a front of the vehicle. In addition, in the vehicle display device  1 , reflected light from the reflection member  40 , which is based on the emission light of the display light, is inverted in vehicle upper and lower directions and projected on the projection target part Rwf. Therefore, the light sources  22  illustrated in here are arranged, in accordance with the eye boxes EB (the first eye box EB 1 , the second eye box EB 2 , and the third eye box EB 3 ) positioned in the vehicle upper and lower directions, in order toward the lower of the vehicle from the light sources  22  corresponding to one, which is disposed closer to the upper of the vehicle (the second eye box EB 2 ), of the eye boxes EB. 
     The back light unit  20 A may only include, as the light sources  22 , those respectively corresponding to the eye boxes EB as described above. However, in the back light unit  20 A illustrated in here, a plurality of other light sources (hereinafter referred to as a plurality of “sub light sources”.)  22  are also provided, as the light sources  22 , in addition to the light sources (hereinafter referred to as a plurality of “main light sources”.)  22  respectively corresponding to the eye boxes EB. The sub light sources  22  are each disposed between each two of the main light sources  22 , which respectively correspond to the eye boxes EB adjacent to each other ( FIGS. 2 and 3 ). In here, a plurality of first main light sources  22 A corresponding to the first eye box EB 1  disposed at the reference position, a plurality of second main light sources  22 B corresponding to the second eye box EB 2  disposed closer to the upper of the vehicle, a plurality of third main light sources  22 C corresponding to the third eye box EB 3  disposed closer to the lower of the vehicle, first sub light sources  22 D disposed between the first main light sources  22 A and the second main light sources  22 B, and second sub light sources  22 E disposed between the first main light sources  22 A and the third main light sources  22 C are provided. 
     In the back light unit  20 A, the first main light sources  22 A, the second main light sources  22 B, the third main light sources  22 C, the first sub light sources  22 D, and the second sub light sources  22 E are respectively provided in the vehicle width directions ( FIG. 3 ). In here, the first main light sources  22 A, the second main light sources  22 B, the third main light sources  22 C, the first sub light sources  22 D, and the second sub light sources  22 E are respectively provided in the vehicle width directions each at the same number (each three in this example). That is, all the light sources  22  are disposed in a grid on the one plane of the substrate  21 . 
     As the light sources  22  illustrated in here, a plurality of light emitting diodes (LEDs) are used. The light sources  22  are supplied with power from a power supply (not illustrated) such as a secondary battery of the vehicle. Furthermore, the controller  50  controls and causes the light sources  22  to turn on or off, as well as controls the output of emission light when the light sources are caused to turn on. 
     The collecting lenses  23  are lens members made of glass or transparent resin that collect light from the light sources  22 , and are respectively provided to correspond to the light sources  22 . The collecting lenses  23  each have an incidence face allowing light to enter and an emission face allowing the light that has entered the incidence face to exit. In addition, for the collecting lenses  23 , the incidence faces are respectively disposed to face light emission parts of the light sources  22 , and the emission faces are disposed to face the display unit  30 A. Each of the collecting lenses  23  illustrated in here is formed to serve as a plane convex lens, where the incidence face is formed into a flat surface and the emission face is formed into a convex, curved surface. Furthermore, the collecting lenses  23  illustrated in here are each formed into a substantially rectangular shape, when viewed from the display unit  30 A. 
     The field lens  24  is a lens member made of glass or transparent resin that aligns, in the advancing direction, light emitted from the collecting lenses  23 , and is disposed between all the collecting lenses  23  and the display unit  30 A. The field lens  24  has an incidence face allowing light to enter and an emission face allowing the light that has entered the incidence face to exit. In addition, for the field lens  24 , the incidence face is disposed to face the emission faces of all the collecting lenses  23 , and the emission face is disposed to face the display unit  30 A. The field lens  24  illustrated in here is formed to serve as a biconvex lens, where the incidence face and the emission face are respectively formed into convex, curved surfaces. Furthermore, the field lens  24  illustrated in here is formed into a substantially rectangular shape, when viewed from the display unit  30 A. 
     The diffusion member  25  is an optical element such as a diffusion plate that diffuses light emitted from the field lens  24  toward the whole of each of the eye boxes EB, and is disposed between the field lens  24  and the display unit  30 A. The diffusion member  25  is formed into a rectangular flat plate shape, where one plane (an incidence face) is disposed to face the emission face of the field lens  24 , and another plane (an emission face) is disposed to face a back face of the display unit  30 A. In the diffusion member  25 , a diffusion angle may be constant in the vehicle upper and lower directions and the vehicle width directions, or otherwise the diffusion angle may vary in the vehicle upper and lower directions and the vehicle width directions. For example, the eye boxes EB used ordinarily each have a longer length in the vehicle width directions than a length in the vehicle upper and lower directions. Therefore, the diffusion member  25 , when it has a wider diffusion angle in the vehicle width directions than a diffusion angle in the vehicle upper and lower directions, makes it possible to increase efficiency when light is diffused toward the whole of each of the eye boxes EB. Furthermore, it is possible to increase its efficiency by using, together with the diffusion member  25 , such an element as a lens array that its diffusion characteristic is a top-hat type, for example. 
     In the back light unit  20 A, light emitted from the diffusion member  25  serves as emission light emitted toward the display unit  30 A. 
     The display unit  30 A according to the present embodiment is configured in such a manner that the back face allows emission light of the back light unit  20 A to enter, and a front face allows display light corresponding to incident light from the back face to be emitted toward the reflection member  40 . For example, as the display unit  30 A, a transmission type thin film transistor (TFT) liquid crystal display is used, for example. The controller  50  controls the display unit  30 A to display the display information. For example, as the display information, image information including characters, numbers, and figures, for example, is displayed. 
     The vehicle display device  1  is configured to allow the controller  50  to perform control as described below in order to provide clear virtual image display regardless of the eye point of the occupant. 
     The controller  50  controls display light in accordance with a detection eye box EBd representing a detection result of one of the eye boxes EB ( FIGS. 1, 4, and 6 ). The controller  50  illustrated in here detects one of the eye boxes EB, which corresponds to the eye point of the occupant, to control display light in accordance with the detection eye box EBd. 
     The controller  50  first detects one of the eye boxes EB on the basis of a detection signal of an eye point detector  71  configured to detect the eye point of the occupant ( FIGS. 1, 4, and 6 ). The vehicle display device  1  may include the eye point detector  71 , or may utilize a detection signal of the eye point detector  71  that the vehicle includes. 
     Next, the controller  50  controls the displaying part  10 A to adjust an emission angle of display light from the displaying part  10 A toward the reflection member  40  in accordance with the detection eye box EBd to project display light reflected by the reflection member  40  at a viewpoint position corresponding to the detection eye box EBd on the projection target part Rwf. Specifically, the controller  50  according to the present embodiment causes the light sources  22  corresponding to the detection eye box EBd to turn on, and causes the light sources  22  corresponding to a plurality of non-detection eye boxes EB 0  other than the detection eye box EBd to turn off to adjust an emission angle of display light from the display unit  30 A toward the reflection member  40  to an emission angle corresponding to the detection eye box EBd ( FIGS. 1, 2, and 4 to 7 ). 
       FIGS. 1 and 2  illustrate a case where the detection eye box EBd corresponds to the first eye box EB 1  disposed at the reference position, the first main light sources  22 A corresponding to the first eye box EB 1  are caused to turn on, and all the rest of the light sources  22  are caused to turn off. In this case, an emission angle of display light from the display unit  30 A toward the reflection member  40  is adjusted to an emission angle corresponding to the first eye box EB 1 , and display light reflected by the reflection member  40  is projected at a viewpoint position Pv 1  corresponding to the first eye box EB 1  on the projection target part Rwf. 
       FIGS. 4 and 5  illustrate a case where the detection eye box EBd corresponds to the second eye box EB 2  disposed closer to the upper of the vehicle, the second main light sources  22 B corresponding to the second eye box EB 2  are caused to turn on, and all the rest of the light sources  22  are caused to turn off. In this case, an emission angle of display light from the display unit  30 A toward the reflection member  40  is adjusted to an emission angle corresponding to the second eye box EB 2 , and display light reflected by the reflection member  40  is projected at a viewpoint position Pv 2  corresponding to the second eye box EB 2  on the projection target part Rwf (the viewpoint position Pv 2  disposed closer to the upper of the vehicle than the viewpoint position Pv 1  corresponding to the first eye box EB 1  disposed at the reference position). 
       FIGS. 6 and 7  illustrate a case where the detection eye box EBd corresponds to the third eye box EB 3  disposed closer to the lower of the vehicle, the third main light sources  22 C corresponding to the third eye box EB 3  are caused to turn on, and all the rest of the light sources  22  are caused to turn off. In this case, an emission angle of display light from the display unit  30 A toward the reflection member  40  is adjusted to an emission angle corresponding to the third eye box EB 3 , and display light reflected by the reflection member  40  is projected at a viewpoint position Pv 3  corresponding to the third eye box EB 3  on the projection target part Rwf (the viewpoint position Pv 3  disposed closer to the lower of the vehicle than the viewpoint position Pv 1  corresponding to the first eye box EB 1  disposed at the reference position). 
     As illustrated above, the vehicle display device  1  according to the present embodiment controls the displaying part  10 A for causing the light sources  22  corresponding to the detection eye box EBd to turn on, and for causing the rest of the light sources  22  to turn off to adjust an emission angle of display light from the displaying part  10 A toward the reflection member  40  to an emission angle corresponding to the detection eye box EBd to project display light reflected by the reflection member  40  at a viewpoint position corresponding to the detection eye box EBd on the projection target part Rwf. Therefore, the vehicle display device  1  makes it possible to provide clear virtual image display in accordance with the eye point of the occupant. 
     Furthermore, in conventional vehicle display devices, in order to diffuse light at a wider angle in accordance with a position of each of the eye boxes EB, for example, a diffusion member having a greater diffusion angle is used, and a decrease in luminance due to the application of such a diffusion member is suppressed by increasing the output of emission light from a light source. However, the vehicle display device  1  according to the present embodiment does not use a diffusion member having a greater diffusion angle, but is able to control the displaying part  10 A for switching the light sources  22  to be caused to turn on to diffuse light at a wider angle in accordance with a position of each of the eye boxes EB. Thus, there is a less decrease in luminance along with a change of each of the eye boxes EB, as can be seen in the conventional vehicle display devices, as well as there is no need to increase the output of the light sources  22 . Therefore, the vehicle display device  1  makes it possible to suppress an increase in power consumption. 
     As described above, the vehicle display device  1  according to the present embodiment makes it possible to suppress an increase in power consumption, and to provide clear virtual image display in accordance with the eye point. 
     By the way, the vehicle display device  1  according to the present embodiment may cause the controller  50  to perform such control as described below, when it is possible to detect a displacement of the detection eye box EBd. 
     When the detection eye box EBd is displaced to the next eye box EB, the controller  50  decreases the output of the main light sources corresponding to the current detection eye box EBd that have been caused to turn on, increases the output of the sub light sources disposed between the main light sources corresponding to the current detection eye box EBd and the main light sources corresponding to the next eye box EBd, decreases the output of the sub light sources when the output of the sub light sources reaches a maximum value, and increases the output of the main light sources corresponding to the next eye box EBd, that is, the next detection eye box EBd ( FIG. 8 ). For example, when the current detection eye box EBd corresponds to the first eye box EB 1  disposed at the reference position, and is displaced to the second eye box EB 2  disposed closer to the upper of the vehicle, the output of the first main light sources  22 A corresponding to the first eye box EB 1  disposed at the reference position, which have been caused to turn on, is decreased, the output of the first sub light sources  22 D disposed between the first main light sources  22 A and the second main light sources  22 B corresponding to the second eye box EB 2  disposed closer to the upper of the vehicle is increased, the output of the first sub light sources  22 D is decreased when the output of the first sub light sources  22 D reaches a maximum value, and the output of the second main light sources  22 B corresponding to the second eye box EB 2  disposed closer to the upper of the vehicle, that is, the next detection eye box EBd is increased. Note that, in  FIG. 8 , a total value of the output of two adjacent sets of the light sources  22  is made constant, and, when the output of one set of the light sources  22  is decreased, the output of the other set of the light sources  22  is increased by the amount of the decrease. However, for example, the controller  50  may determine, in order to increase or decrease a total value of the output of the two adjacent sets of the light sources  22  in accordance with the eye point (one of the eye boxes EB), an amount of decrease for the output of one set of the light sources  22  and an amount of increase for the output of the other set of the light sources  22 . 
     Therefore, the vehicle display device  1  according to the present embodiment makes it possible to decrease an amount of change in luminance along with a change of the eye point of the occupant in the vehicle upper and lower directions. 
     Furthermore, the vehicle display device  1  according to the present embodiment may cause the controller  50  to perform such control as described below, when it is possible to detect not only a change of the eye point of the occupant in the vehicle upper and lower directions, but also a change of the eye point of the occupant in the vehicle width directions. In the vehicle display device  1  in this case, the light sources  22  are set to respectively correspond to the eye points of an occupant to allow each set to correspond to the eye point of the occupant. In addition, the controller  50  causes only the light sources  22  corresponding to the detection eye point to turn on, for example. Furthermore, the controller  50  causes, for example, the light sources  22  corresponding to the detection eye point and all the light sources  22  around the light sources  22  corresponding to the detection eye point to turn on, and causes all the rest of the light sources  22  to turn off. The vehicle display device  1  according to the present embodiment makes it possible, through such control as described above, to decrease an amount of change in luminance along with a change of the eye point of the occupant in various directions. 
     Furthermore, the vehicle display device  1  according to the present embodiment may be configured in such a manner that the reflection member  40  is provided with a rotation axis (not illustrated) having an axis line extending in the vehicle width directions, and the controller  50  rotates the reflection member  40  around the rotation axis. In this case, the controller  50  may rotate the reflection member  40  and perform the control described above to project display light reflected by the reflection member  40  at a viewpoint position corresponding to the detection eye box EBd on the projection target part Rwf. Furthermore, in this case, the controller  50  may recognize the detection eye box EBd on the basis of a rotated position of the reflection member  40 . 
     Note herein that the vehicle display device  1  exemplified in here is configured and disposed in such a manner that the displaying part  10 A is disposed closer to the rear of the vehicle than the reflection member  40 , the displaying part  10 A emits display light toward the reflection member  40  disposed closer to the front of the vehicle, and reflected light from the reflection member  40 , which is based on the emission light, is inverted in the vehicle upper and lower directions and projected on the projection target part Rwf. However, the vehicle display device  1  according to the present embodiment may be configured and disposed as described below. 
     For example, the vehicle display device  1  according to the present embodiment may be configured and disposed (not illustrated) in such a manner that the displaying part  10 A is disposed closer to the front of the vehicle and the lower of the vehicle than the reflection member (hereinafter referred to as a “first reflection member”.)  40 , another reflection member (hereinafter referred to as a “second reflection member”.) is disposed closer to the front of the vehicle than the first reflection member  40 , the displaying part  10 A emits display light toward the first reflection member  40 , reflected light from the first reflection member  40 , which is based on the emission light, is inverted in the vehicle upper and lower directions by the second reflection member and projected, and reflected light from the second reflection member, which is based on the projection light, is inverted in the vehicle upper and lower directions and projected on the projection target part Rwf. In this case, the light sources  22  are arranged, similar to the example described above, in accordance with the eye boxes EB (the first eye box EB 1 , the second eye box EB 2 , and the third eye box EB 3 ) positioned in the vehicle upper and lower directions, in order toward the lower of the vehicle from the light sources  22  corresponding to one, which is disposed closer to the upper of the vehicle (the second eye box EB 2 ), of the eye boxes EB. 
     Furthermore, for example, the vehicle display device  1  according to the present embodiment may be configured and disposed (not illustrated) in such a manner that the displaying part  10 A is disposed closer to the front of the vehicle than the reflection member  40 , the displaying part  10 A emits display light toward the reflection member  40  disposed closer to the rear of the vehicle, and reflected light from the reflection member  40 , which is based on the emission light, is not inverted in the vehicle upper and lower directions, but projected on the projection target part Rwf. Furthermore, the vehicle display device  1  according to the present embodiment may be configured and disposed (not illustrated) in such a manner that the displaying part  10 A is disposed closer to the rear of the vehicle than the reflection member (hereinafter referred to as the “first reflection member”.)  40 , another reflection member (hereinafter referred to as the “second reflection member”.) is disposed closer to the rear of the vehicle and the upper of the vehicle than the first reflection member  40 , the displaying part  10 A emits display light toward the first reflection member  40  disposed closer to the front of the vehicle, and reflected light from the first reflection member  40 , which is based on the emission light, is not inverted in the vehicle upper and lower directions by the second reflection member, but projected, and reflected light from the second reflection member, which is based on the projection light, is not inverted in the vehicle upper and lower directions, but projected on the projection target part Rwf. When configured and disposed as described above, in order to suppress a virtual image from being inverted in the vehicle upper and lower directions, the light sources  22  are arranged, in accordance with the eye boxes EB (the first eye box EB 1 , the second eye box EB 2 , and the third eye box EB 3 ) positioned in the vehicle upper and lower directions, in order toward the upper of the vehicle from the light sources  22  corresponding to one, which is disposed closer to the upper of the vehicle (the second eye box EB 2 ), of the eye boxes EB. 
     Note that, although the vehicle display device  1  according to the present embodiment has been illustrated, where such control as described above is performed on the basis of the detection eye box EBd, such control as described above may be performed on the basis of a detection eye point detected from a detection signal of the eye point detector  71 . In this case, the eye box described above is read as an eye point. 
     First Modification Example 
     Next, the vehicle display device  2  according to the first modification example will now be described herein. 
     In the vehicle display device  2  according to the modification example, the displaying part  10  including the back light unit  20  and the display unit  30  is configured as a displaying part  10 B including a back light unit  20 B and a display unit  30 B, as described below ( FIG. 9 ). 
     The back light unit  20 B according to the modification example includes a substrate  121 , a plurality of light sources  122 , a plurality of collecting lenses  123 , a field lens  124 , and a diffusion member  125  ( FIG. 9 ). In the back light unit  20 B, the collecting lenses  123  collect emission light from the light sources  122 . The emission light from the collecting lenses  123  then enters the field lens  124 . In the back light unit  20 B, the field lens  124  refracts the incident light. Emission light aligned in the advancing direction by the field lens  124  enters the diffusion member  125 . The diffusion member  125  diffuses the incident light at a wide angle preferable for the display unit  30 B. The diffused light is then emitted toward the display unit  30 B. 
     The substrate  121  is a member for fixing the light sources  122 . The substrate  121  is formed into a rectangular flat plate shape, similar to the substrate  21  according to the present embodiment. The light sources  122  are fixed to one plane ( FIG. 9 ). 
     As the light sources  122 , a plurality of light emitting diodes are used, similar to the light sources  22  according to the present embodiment. The controller  50  controls and causes the light sources to turn on or off, as well as controls the output of emission light when the light sources are caused to turn on. The light sources  122  according to the modification example are arranged two in the vehicle upper and lower directions by three in the vehicle width directions, for example. 
     The collecting lenses  123  are lens members made of glass or transparent resin that collect light from the light sources  122 , and are respectively provided to correspond to the light sources  122 . The collecting lenses  123  according to the modification example are each formed into an identical plane convex lens to that of the collecting lenses  23  according to the present embodiment. Their flat incidence faces are respectively disposed to face light emission parts of the light sources  122 , and their convex emission faces are disposed to face the display unit  30 B. Light from the light sources  122  via the collecting lenses  123  may enter regions divided on a back face of the display unit  30 B, or may enter in an overlapped manner part or whole of the regions adjacent to each other. 
     The field lens  124  is a lens member made of glass or transparent resin that aligns, in the advancing direction, light emitted from the collecting lenses  123 , and is disposed between all the collecting lenses  123  and the display unit  30 B. The field lens  124  has an incidence face allowing light to enter and an emission face allowing the light that has entered the incidence face to exit. In addition, for the field lens  124 , the incidence face is disposed to face the emission faces of all the collecting lenses  123 , and the emission face is disposed to face the display unit  30 B. The field lens  124  illustrated in here is formed to serve as a plane concave lens, where the incidence face is formed into a flat surface and the emission face is formed into a concave, curved face. That is, in the field lens  124  illustrated in here, the emission face allowing light entering the incidence face from the light sources  122  to exit toward the display unit  30 B is formed into a concave, curved face. Furthermore, the field lens  124  illustrated in here is formed into a substantially rectangular shape, when viewed from the display unit  30 B. 
     The diffusion member  125  is an optical element such as a diffusion plate that diffuses light emitted from the field lens  124  toward the whole of each of the eye boxes EB, and is disposed between the field lens  124  and the display unit  30 B. The diffusion member  125  according to the modification example is identical to the diffusion member  25  according to the present embodiment, where one plane (an incidence face) is disposed to face the emission face of the field lens  124 , and another plane (an emission face) is disposed to face the back face of the display unit  30 B. 
     For the back light unit  20 B, similar to the present embodiment, it is possible to increase its efficiency when light is diffused toward the whole of each of the eye boxes EB by using, together with the diffusion member  125 , such an element as a lens array that its diffusion characteristic is a top-hat type, for example. 
     In the back light unit  20 B, light emitted from the diffusion member  125  serves as emission light emitted toward the display unit  30 B. 
     The display unit  30 B according to the modification example is identical to the display unit  30 A according to the present embodiment described above. In addition, the vehicle display device  2  according to the modification example is configured and disposed, similar to the vehicle display device  1  specifically exemplified in the present embodiment, in such a manner that the displaying part  10 B is disposed closer to the rear of the vehicle than the reflection member  40 , the displaying part  10 B emits display light toward the reflection member  40  disposed closer to the front of the vehicle, and reflected light from the reflection member  40 , which is based on the emission light, is inverted in the vehicle upper and lower directions and projected on the projection target part Rwf. 
     The vehicle display device  2  is configured to allow the controller  50  to perform control as described below in order to provide clear virtual image display regardless of the eye point of the occupant. 
     The controller  50  relatively moves the field lens  124  relative to the light sources  122  on the basis of the detection eye box EBd representing a detection result of one of the eye boxes EB to control display light in accordance with the detection eye box EBd ( FIGS. 1, 4, and 6 ). The controller  50  illustrated in here detects one of the eye boxes EB, which corresponds to the eye point of the occupant, to relatively move the field lens  124  on the basis of the detection eye box EBd. 
     To achieve this feature, the back light unit  20 B according to the modification example is provided with a driving part  126  configured to relatively move the field lens  124  relative to the light sources  122  to change an emission angle of light from the emission face of the field lens  124  ( FIGS. 10 and 11 ). The driving part  126  illustrated in here is used to relatively move the field lens  124  relative to the light sources  122  in the vehicle upper and lower directions. For example, the driving part  126  includes an electric motor  126 A serving as a drive source, a pinion gear  126 B that is attached to and that is coaxial with an output shaft of the electric motor  126 A, and a rack gear  126 C that is fixed to the field lens  124  and that is engaging with the pinion gear  126 B. The driving part  126  allows drive torque of the electric motor  126 A to be transmitted via the pinion gear  126 B to the rack gear  126 C to move the rack gear  126 C in one of the vehicle upper and lower directions to relatively move the field lens  124  to which the rack gear  126 C is attached in the one of the vehicle upper and lower directions. 
     The controller  50  first detects, similar to the present embodiment, one of the eye boxes EB on the basis of a detection signal of the eye point detector  71 . 
     Next, the controller  50  controls the driving part  126  to relatively move the field lens  124  to a position at which an emission angle of light from the emission face of the field lens  124  corresponds to an emission angle corresponding to the detection eye box EBd to adjust an emission angle of display light from the display unit  30 B toward the reflection member  40  to an emission angle corresponding to the detection eye box EBd ( FIGS. 1, 4, 6, 9, 12, and 13 ). The displaying part  10 B exemplified in here is disposed closer to the rear of the vehicle than the reflection member  40  to emit display light toward the reflection member  40  disposed closer to the front of the vehicle. Therefore, the controller  50  controls the driving part  126  as described below. 
     When the detection eye box EBd corresponds to the first eye box EB 1  disposed at the reference position, the controller  50  controls the driving part  126  to relatively move the field lens  124  to a reference lens position at which an emission angle of light from the emission face of the field lens  124  corresponds to an emission angle corresponding to the first eye box EB 1  disposed at the reference position ( FIG. 9 ). Therefore, display light reflected by the reflection member  40  is projected at the viewpoint position Pv 1  corresponding to the first eye box EB 1  on the projection target part Rwf. 
     Furthermore, when the detection eye box EBd corresponds to the second eye box EB 2  disposed closer to the upper of the vehicle, the controller  50  controls the driving part  126  to relatively move the field lens  124  toward a position closer to the upper of the vehicle than the reference lens position to adjust an emission angle of light from the emission face of the field lens  124  to an emission angle corresponding to the second eye box EB 2  disposed closer to the upper of the vehicle ( FIG. 12 ). Therefore, display light reflected by the reflection member  40  is projected at the viewpoint position Pv 2  corresponding to the second eye box EB 2  on the projection target part Rwf. 
     Furthermore, when the detection eye box EBd corresponds to the third eye box EB 3  disposed closer to the lower of the vehicle, the controller  50  controls the driving part  126  to relatively move the field lens  124  toward a position closer to the lower of the vehicle than the reference lens position to adjust an emission angle of light from the emission face of the field lens  124  to an emission angle corresponding to the third eye box EB 3  disposed closer to the lower of the vehicle ( FIG. 12 ). Therefore, display light reflected by the reflection member  40  is projected at the viewpoint position Pv 3  corresponding to the third eye box EB 3  on the projection target part Rwf. 
     As illustrated above, the vehicle display device  2  according to the modification example controls the displaying part  10 B for relatively moving the field lens  124  relative to the light sources  122  in accordance with the detection eye box EBd and for adjusting an emission angle of light from the emission face of the field lens  124  to an emission angle corresponding to the detection eye box EBd to adjust an emission angle of display light from the displaying part  10 B toward the reflection member  40  to an emission angle corresponding to the detection eye box EBd to project display light reflected by the reflection member  40  at a viewpoint position corresponding to the detection eye box EBd on the projection target part Rwf. Therefore, the vehicle display device  2  makes it possible to provide clear virtual image display in accordance with the eye point of the occupant. 
     Furthermore, the vehicle display device  2  according to the modification example does not use a diffusion member having a greater diffusion angle, but is able to control the displaying part  10 B for changing a position of the field lens  124  relative to the light sources  122  to diffuse light at a wider angle in accordance with a position of each of the eye boxes EB. Thus, there is a less decrease in luminance along with a change of each of the eye boxes EB, as can be seen in the conventional vehicle display devices, as well as there is no need to increase the output of the light sources  122 . Therefore, the vehicle display device  2  makes it possible to suppress an increase in power consumption. 
     As described above, the vehicle display device  2  according to the modification example makes it possible to suppress an increase in power consumption, and to provide clear virtual image display in accordance with the eye point. 
     By the way, as to the relative movement directions of the field lens  124  relative to the light sources  122 , the vehicle display device  2  according to the modification example may include a driving part making it possible to relatively move the field lens  124  in the vehicle width directions or/and vehicle front and rear directions, in addition to the vehicle upper and lower directions. In this case, in the vehicle display device  2 , the controller  50  controls the driving part to relatively move the field lens  124  relative to the light sources  122  in the vehicle width directions or/and the vehicle front and rear directions, in addition to the vehicle upper and lower directions, making it possible to provide clear virtual image display in accordance with the eye point of the occupant. 
     Furthermore, the vehicle display device  2  according to the modification example may be configured, similar to the present embodiment, in such a manner that the reflection member  40  is provided with a rotation axis (not illustrated) having an axis line extending in the vehicle width directions, and the controller  50  rotates the reflection member  40  around the rotation axis. In addition, similar to the present embodiment, the controller  50  according to the modification example may rotate the reflection member  40  and perform such control as described above to project display light reflected by the reflection member  40  at a viewpoint position corresponding to the detection eye box EBd on the projection target part Rwf. In this case, the controller  50  may recognize the detection eye box EBd on the basis of a rotated position of the reflection member  40 . 
     Note herein that the vehicle display device  2  exemplified in here is configured and disposed, similar to the vehicle display device  1  specifically exemplified in the present embodiment, in such a manner that the displaying part  10 B is disposed closer to the rear of the vehicle than the reflection member  40 , the displaying part  10 B emits display light toward the reflection member  40  disposed closer to the front of the vehicle, and reflected light from the reflection member  40 , which is based on the emission light, is inverted in the vehicle upper and lower directions and projected on the projection target part Rwf. However, the vehicle display device  2  according to the modification example may be configured and disposed as described below. 
     For example, the vehicle display device  2  according to the modification example may be configured and disposed (not illustrated), similar to the one illustrated as another form of the vehicle display device  1  in the present embodiment, in such a manner that the displaying part  10 B is disposed closer to the front of the vehicle and the lower of the vehicle than the first reflection member  40 , a second reflection member is disposed closer to the front of the vehicle than the first reflection member  40 , the displaying part  10 B emits display light toward the first reflection member  40 , reflected light from the first reflection member  40 , which is based on the emission light, is inverted in the vehicle upper and lower directions by the second reflection member and projected, and reflected light from the second reflection member, which is based on the projection light, is inverted in the vehicle upper and lower directions and projected on the projection target part Rwf. Even in this case, the controller  50  controls the driving part  126 , similar to the example described above. 
     Furthermore, for example, the vehicle display device  2  according to the modification example may be configured and disposed (not illustrated), similar to the one illustrated as another form of the vehicle display device  1  in the present embodiment, in such a manner that the displaying part  10 B is disposed closer to the front of the vehicle than the reflection member  40 , the displaying part  10 B emits display light toward the reflection member  40  disposed closer to the rear of the vehicle, and reflected light from the reflection member  40 , which is based on the emission light, is not inverted in the vehicle upper and lower directions, but projected on the projection target part Rwf. Furthermore, the vehicle display device  2  according to the modification example may be configured and disposed (not illustrated), similar to the one illustrated as another form of the vehicle display device  1  in the present embodiment, in such a manner that the displaying part  10 B is disposed closer to the rear of the vehicle than the first reflection member  40 , a second reflection member is disposed closer to the rear of the vehicle and the upper of the vehicle than the first reflection member  40 , the displaying part  10 B emits display light toward the first reflection member  40  disposed closer to the front of the vehicle, reflected light from the first reflection member  40 , which is based on the emission light, is not inverted in the vehicle upper and lower directions by the second reflection member, but projected, and reflected light from the second reflection member, which is based on the projection light, is not inverted in the vehicle upper and lower directions, but projected on the projection target part Rwf. 
     Even when configured and disposed as described above, when the detection eye box EBd corresponds to the first eye box EB 1  disposed at the reference position, the controller  50  controls the driving part  126  to relatively move the field lens  124  at the reference lens position at which an emission angle of light from the emission face of the field lens  124  corresponds to an emission angle corresponding to the first eye box EB 1  disposed at the reference position. 
     On the other hand, when the detection eye box EBd corresponds to the second eye box EB 2  disposed closer to the upper of the vehicle, in order to suppress a virtual image from being inverted in the vehicle upper and lower directions, the controller  50  controls the driving part  126  to relatively move the field lens  124  to a position closer to the lower of the vehicle than the reference lens position to adjust an emission angle of light from the emission face of the field lens  124  to an emission angle corresponding to the second eye box EB 2  disposed closer to the upper of the vehicle. Furthermore, when the detection eye box EBd corresponds to the third eye box EB 3  disposed closer to the lower of the vehicle, in order to suppress a virtual image from being inverted in the vehicle upper and lower directions, the controller  50  controls the driving part  126  to relatively move the field lens  124  to a position closer to the upper of the vehicle than the reference lens position to adjust an emission angle of light from the emission face of the field lens  124  to an emission angle corresponding to the third eye box EB 3  disposed closer to the lower of the vehicle. 
     Note that, although the vehicle display device  2  according to the modification example has been illustrated, where such control as described above is performed on the basis of the detection eye box EBd, such control as described above may be performed on the basis of a detection eye point detected from a detection signal of the eye point detector  71 . In this case, the eye box described above is read as an eye point. 
     Second Modification Example 
     Next, the vehicle display device  3  according to the second modification example will now be described herein. 
     In the vehicle display device  3  according to the modification example, the displaying part  10  including the back light unit  20  and the display unit  30  is configured as a displaying part  10 C including a back light unit  20 C and a display unit  30 C, as described below ( FIG. 14 ). 
     The back light unit  20 C according to the modification example includes a substrate  221 , a plurality of light sources  222 , a plurality of collecting lenses  223 , a field lens  224 , and a diffusion member  225  ( FIG. 14 ). In the back light unit  20 C, the collecting lenses  223  collect emission light from the light sources  222 . The emission light from the collecting lenses  223  then enters the field lens  224 . In the back light unit  20 C, the field lens  224  refracts the incident light. Emission light aligned in the advancing direction by the field lens  224  enters the diffusion member  225 . The diffusion member  225  diffuses the incident light at a wide angle preferable for the display unit  30 C. The diffused light is then emitted toward the display unit  30 C. 
     The substrate  221  is a member for fixing the light sources  222 . The substrate  221  is formed into a rectangular flat plate shape, similar to the substrate  121  according to the first modification example. The light sources  222  are fixed to one plane ( FIG. 14 ). 
     As the light sources  222 , a plurality of light emitting diodes are used, similar to the light sources  122  according to the first modification example. The controller  50  controls and causes the light sources to turn on or off, as well as controls the output of emission light when the light sources are caused to turn on. The light sources  222  according to the modification example are arranged, similar to the light sources  122  according to the first modification example, two in the vehicle upper and lower directions by three in the vehicle width directions. 
     The collecting lenses  223  are lens members made of glass or transparent resin that collect light from the light sources  222 , and are respectively provided to correspond to the light sources  222 . The collecting lenses  223  according to the modification example are each formed into an identical plane convex lens to that of the collecting lenses  123  according to the first modification example. Their flat incidence faces are respectively disposed to face light emission parts of the light sources  222 , and their convex emission faces are disposed to face the display unit  30 C. Light from the light sources  222  via the collecting lenses  223  may enter regions divided on a back face of the display unit  30 C, or may enter in an overlapped manner part or whole of the regions adjacent to each other. 
     The field lens  224  is a lens member made of glass or transparent resin that aligns, in the advancing direction, light emitted from the collecting lenses  223 , and is disposed between all of the collecting lenses  223  and the display unit  30 C. The field lens  224  according to the modification example is formed into an identical plane concave lens to that of the field lens  124  according to the first modification example. Its flat incidence face is disposed to face the emission faces of all the collecting lenses  223 , and its concave emission face is disposed to face the display unit  30 C. 
     The diffusion member  225  is an optical element such as a diffusion plate that diffuses light emitted from the field lens  224  toward the whole of each of the eye boxes EB, and is disposed between the field lens  224  and the display unit  30 C. The diffusion member  225  according to the modification example is identical to the diffusion member  125  according to the first modification example, where one plane (an incidence face) is disposed to face the emission face of the field lens  224 , and another plane (an emission face) is disposed to face the back face of the display unit  30 C. 
     For the back light unit  20 C, similar to the present embodiment and the first modification example, it is possible to increase its efficiency when light is diffused toward the whole of each of the eye boxes EB by using, together with the diffusion member  225 , such an element as a lens array that its diffusion characteristic is a top-hat type, for example. 
     In the back light unit  20 C, light emitted from the diffusion member  225  serves as emission light emitted toward the display unit  30 C. 
     The display unit  30 C according to the modification example is identical to the display unit  30 A according to the present embodiment (the display unit  30 B according to the first modification example) described above. In addition, the vehicle display device  3  according to the modification example is configured and disposed, similar to the vehicle display device  1  specifically exemplified in the present embodiment, in such a manner that the displaying part  10 C is disposed closer to the rear of the vehicle than the reflection member  40 , the displaying part  10 C emits display light toward the reflection member  40  disposed closer to the front of the vehicle, and reflected light from the reflection member  40 , which is based on the emission light, is inverted in the vehicle upper and lower directions and projected on the projection target part Rwf. 
     The vehicle display device  3  is configured to allow the controller  50  to perform control as described below in order to provide clear virtual image display regardless of the eye point of the occupant. 
     The controller  50  relatively rotates the displaying part  10 C relative to a vehicle body on the basis of the detection eye box EBd representing a detection result of one of the eye boxes EB to control display light in accordance with the detection eye box EBd ( FIGS. 1, 4, and 6 ). The controller  50  illustrated in here detects one of the eye boxes EB, which corresponds to the eye point of the occupant, to relatively rotate the displaying part  10 C on the basis of the detection eye box EBd. 
     To achieve this feature, the vehicle display device  3  according to the modification example is provided with a driving part  80  configured to relatively rotate the displaying part  10 C relative to the vehicle body ( FIGS. 15 to 18 ). The driving part  80  relatively rotates the displaying part  10 C relative to the vehicle body around a rotation axis  63  having an axis line extending in the vehicle width directions to change an emission angle of display light from the displaying part  10 C. In here, the rotation axis  63  is provided to the housing  61  of the back light unit  20 C. While the back light unit  20 C is relatively rotated, the display unit  30 C fixed to the housing  61  of the back light unit  20 C is also relatively rotated. 
     For example, the driving part  80  includes an electric motor  81  serving as a drive source, a worm gear  82  that is attached to and that is coaxial with an output shaft of the electric motor  81 , and a rack gear  83  that is fixed to the housing  61  of the back light unit  20 C and that is engaging with the worm gear  82  ( FIGS. 15 and 16 ). On the rack gear  83 , a plurality of teeth are arranged on its outside in a radial direction, when viewed from the axis line of the rotation axis  63 , in a convex arc shape on the outside. The driving part  80  allows drive torque of the electric motor  81  to be transmitted via the worm gear  82  to the rack gear  83  to rotate the rack gear  83  around the rotation axis  63  in one of the vehicle upper and lower directions to relatively rotate the housing  61  to which the rack gear  83  is attached around the rotation axis  63 . 
     Furthermore, the driving part  80  may include an electric motor  85  serving as a drive source, a male thread part  86  formed on an output shaft of the electric motor  85 , a power transmitting tool  87  having a female thread part (not illustrated) screwed with the male thread part  86 , a transmitted power receiving part  88  that is provided to the housing  61  of the back light unit  20 C and that receives a force from the power transmitting tool  87 , and a guide tool  89  that guides the power transmitting tool  87  in the vehicle upper and lower directions ( FIGS. 17 and 18 ). The power transmitting tool  87  includes a power transmitting part  87   a  having a protrusion shape protruding toward the upper of the vehicle or the lower of the vehicle, and transmits a force from the power transmitting part  87   a  to the transmitted power receiving part  88 . Furthermore, the power transmitting tool  87  includes a guide target part  87   b  that is to be guided in the vehicle upper and lower directions along a guide shaft  89   a  of the guide tool  89 . The power transmitting part  87   a  illustrated in here protrudes toward the upper of the vehicle. In the power transmitting tool  87 , when an axial force generated by the male thread part  86  and the female thread part acts toward the upper of the vehicle, the power transmitting part  87   a  pushes up the transmitted power receiving part  88  toward the upper of the vehicle, and the housing  61  to which the transmitted power receiving part  88  is attached is relatively rotated around the rotation axis  63 . In addition, in the power transmitting tool  87 , when an axial force generated by the male thread part  86  and the female thread part acts toward the lower of the vehicle, a force acting from the power transmitting part  87   a  to the transmitted power receiving part  88  disappears, the power transmitting part  87   a  moves toward the lower of the vehicle, the transmitted power receiving part  88  also moves toward the lower of the vehicle, and the housing  61  to which the transmitted power receiving part  88  is attached is relatively rotated around the rotation axis  63 . 
     The controller  50  first detects, similar to the present embodiment and the first modification example, one of the eye boxes EB on the basis of a detection signal of the eye point detector  71 . 
     Next, the controller  50  controls the driving part  80  to relatively rotate the displaying part  10 C to a position at which an emission angle of display light from the display unit  30 C toward the reflection member  40  corresponds to an emission angle corresponding to the detection eye box EBd ( FIGS. 1, 4, 6, 14, 19, and 20 ). The displaying part  10 C exemplified in here is disposed closer to the rear of the vehicle than the reflection member  40  to emit display light toward the reflection member  40  disposed closer to the front of the vehicle. Therefore, the controller  50  controls the driving part  80  as described below. 
     When the detection eye box EBd corresponds to the first eye box EB 1  disposed at the reference position, the controller  50  controls the driving part  80  to relatively rotate the displaying part  10 C to a reference displaying part position at which an emission angle of display light from the display unit  30 C toward the reflection member  40  corresponds to an emission angle corresponding to the first eye box EB 1  disposed at the reference position ( FIG. 14 ). Therefore, display light reflected by the reflection member  40  is projected at the viewpoint position Pv 1  corresponding to the first eye box EB 1  on the projection target part Rwf. 
     Furthermore, when the detection eye box EBd corresponds to the second eye box EB 2  disposed closer to the upper of the vehicle, the controller  50  controls the driving part  80  to relatively rotate the displaying part  10 C to allow a front face of the display unit  30 C to face a position closer to the lower of the vehicle than the reference displaying part position to adjust an emission angle of display light from the display unit  30 C toward the reflection member  40  to an emission angle corresponding to the second eye box EB 2  disposed closer to the upper of the vehicle ( FIG. 19 ). Therefore, display light reflected by the reflection member  40  is projected at the viewpoint position Pv 2  corresponding to the second eye box EB 2  on the projection target part Rwf. 
     Furthermore, when the detection eye box EBd corresponds to the third eye box EB 3  disposed closer to the lower of the vehicle, the controller  50  controls the driving part  80  to relatively rotate the displaying part  10 C to allow the front face of the display unit  30 C to face a position closer to the upper of the vehicle than the reference displaying part position to adjust an emission angle of display light from the display unit  30 C toward the reflection member  40  to an emission angle corresponding to the third eye box EB 3  disposed closer to the lower of the vehicle ( FIG. 20 ). Therefore, display light reflected by the reflection member  40  is projected at the viewpoint position Pv 3  corresponding to the third eye box EB 3  on the projection target part Rwf. 
     As illustrated above, the vehicle display device  3  according to the modification example controls the displaying part  10 C for relatively moving the displaying part  10 C relative to the vehicle body in accordance with the detection eye box EBd to adjust an emission angle of display light from the displaying part  10 C toward the reflection member  40  to an emission angle corresponding to the detection eye box EBd to project display light reflected by the reflection member  40  at a viewpoint position corresponding to the detection eye box EBd on the projection target part Rwf. Therefore, the vehicle display device  3  makes it possible to provide clear virtual image display in accordance with the eye point of the occupant. 
     Furthermore, the vehicle display device  3  according to the modification example does not use a diffusion member having a greater diffusion angle, but is able to control the displaying part  10 C for relatively rotating the displaying part  10 C relative to the vehicle body, and for changing the orientation of the front face of the display unit  30 C of the displaying part  10 C to diffuse light at a wider angle in accordance with a position of each of the eye boxes EB. Thus, there is a less decrease in luminance along with a change of each of the eye boxes EB, as can be seen in the conventional vehicle display devices, as well as there is no need to increase the output of the light sources  222 . Therefore, the vehicle display device  3  makes it possible to suppress an increase in power consumption. 
     As described above, the vehicle display device  3  according to the modification example makes it possible to suppress an increase in power consumption, and to provide clear virtual image display in accordance with the eye point. 
     By the way, the vehicle display device  3  according to the modification example may be configured in such a manner that the position of the display unit  30 C relative to the vehicle body is fixed, and the back light unit  20 C is relatively rotated relative to the vehicle body, as described above. In this case, the controller  50  relatively rotates the back light unit  20 C to adjust an emission angle of emission light from the back light unit  20 C to an emission angle corresponding to the detection eye box EBd to adjust an emission angle of display light from the displaying part  10 C (the display unit  30 C) toward the reflection member  40  to an emission angle corresponding to the detection eye box EBd to project display light reflected by the reflection member  40  at a viewpoint position corresponding to the detection eye box EBd on the projection target part Rwf. 
     Furthermore, the vehicle display device  3  according to the modification example may be configured in such a manner that the position of the display unit  30 C relative to the vehicle body and the positions of the housing  61  and the diffusion member  225  of the back light unit  20 C relative to the vehicle body are fixed, and the substrate  221 , the light sources  222 , the collecting lenses  223 , and the field lens  224  in the back light unit  20 C are relatively rotated together relative to the vehicle body. In this case, the controller  50  relatively rotates the substrate  221 , the light sources  222 , the collecting lenses  223 , and the field lens  224  together relative to the vehicle body to adjust an emission angle of emission light from the back light unit  20 C to an emission angle corresponding to the detection eye box EBd to adjust an emission angle of display light from the displaying part  10 C (the display unit  30 C) toward the reflection member  40  to an emission angle corresponding to the detection eye box EBd to project display light reflected by the reflection member  40  at a viewpoint position corresponding to the detection eye box EBd on the projection target part Rwf. 
     Furthermore, the vehicle display device  3  according to the modification example may be configured, similar to the present embodiment and the first modification example, in such a manner that the reflection member  40  is provided with a rotation axis (not illustrated) having an axis line extending in the vehicle width directions, and the controller  50  rotates the reflection member  40  around the rotation axis. In addition, the controller  50  according to the modification example may, similar to the present embodiment, rotate the reflection member  40  and perform such control as described above to project display light reflected by the reflection member  40  at a viewpoint position corresponding to the detection eye box EBd on the projection target part Rwf. In this case, the controller  50  may recognize the detection eye box EBd on the basis of a rotated position of the reflection member  40 . 
     Note herein that the vehicle display device  3  exemplified in here is configured and disposed, similar to the vehicle display device  1  specifically exemplified in the present embodiment, for example, in such a manner that the displaying part  10 C is disposed closer to the rear of the vehicle than the reflection member  40 , the displaying part  10 C emits display light toward the reflection member  40  disposed closer to the front of the vehicle, and reflected light from the reflection member  40 , which is based on the emission light, is inverted in the vehicle upper and lower directions and projected on the projection target part Rwf. However, the vehicle display device  3  according to the modification example may be configured and disposed as described below. 
     For example, the vehicle display device  3  according to the modification example may be configured and disposed (not illustrated), similar to the one illustrated as another form of the vehicle display device  1  in the present embodiment, in such a manner that the displaying part  10 C is disposed closer to the front of the vehicle and the lower of the vehicle than the first reflection member  40 , a second reflection member is disposed closer to the front of the vehicle than the first reflection member  40 , the displaying part  10 C emits display light toward the first reflection member  40 , reflected light from the first reflection member  40 , which is based on the emission light, is inverted in the vehicle upper and lower directions by the second reflection member and projected, and reflected light from the second reflection member, which is based on the projection light, is inverted in the vehicle upper and lower directions and projected on the projection target part Rwf. Even in this case, the controller  50  controls the driving part  80 , similar to the example described above. 
     Furthermore, for example, the vehicle display device  3  according to the modification example may be configured and disposed (not illustrated), similar to the one illustrated as another form of the vehicle display device  1  in the present embodiment, in such a manner that the displaying part  10 C is disposed closer to the front of the vehicle than the reflection member  40 , the displaying part  10 C emits display light toward the reflection member  40  disposed closer to the rear of the vehicle, reflected light from the reflection member  40 , which is based on the emission light, is not inverted in the vehicle upper and lower directions, but projected on the projection target part Rwf. Furthermore, the vehicle display device  3  according to the modification example may be configured and disposed (not illustrated), similar to the one illustrated as another form of the vehicle display device  1  in the present embodiment, in such a manner that the displaying part  10 C is disposed closer to the rear of the vehicle than the first reflection member  40 , a second reflection member is disposed closer to the rear of the vehicle and the upper of the vehicle than the first reflection member  40 , the displaying part  10 C emits display light toward the first reflection member  40  disposed closer to the front of the vehicle, reflected light from the first reflection member  40 , which is based on the emission light, is not inverted in the vehicle upper and lower directions by the second reflection member, but projected, and reflected light from the second reflection member, which is based on the projection light, is not inverted in the vehicle upper and lower directions, but projected on the projection target part Rwf. 
     Even when configured and disposed as described above, when the detection eye box EBd corresponds to the first eye box EB 1  disposed at the reference position, the controller  50  controls the driving part  80  to relatively rotate the displaying part  10 C to the reference displaying part position at which an emission angle of display light from the display unit  30 C toward the reflection member  40  corresponds to an emission angle corresponding to the first eye box EB 1  disposed at the reference position. 
     On the other hand, when the detection eye box EBd corresponds to the second eye box EB 2  disposed closer to the upper of the vehicle, the controller  50  controls the driving part  80  to relatively rotate the displaying part  10 C to allow the front face of the display unit  30 C to face a position closer to the upper of the vehicle than the reference displaying part position to adjust an emission angle of display light from the display unit  30 C toward the reflection member  40  to an emission angle corresponding to the second eye box EB 2  disposed closer to the upper of the vehicle. Furthermore, when the detection eye box EBd corresponds to the third eye box EB 3  disposed closer to the lower of the vehicle, the controller  50  controls the driving part  80  to relatively rotate the displaying part  10 C to allow the front face of the display unit  30 C to face a position closer to the lower of the vehicle than the reference displaying part position to adjust an emission angle of display light from the display unit  30 C toward the reflection member  40  to an emission angle corresponding to the third eye box EB 3  disposed closer to the lower of the vehicle. 
     Note that, although the vehicle display device  3  according to the modification example has been illustrated, where such control as described above is performed on the basis of the detection eye box EBd, such control as described above may be performed on the basis of a detection eye point detected from a detection signal of the eye point detector  71 . In this case, the eye box described above is read as an eye point. 
     The vehicle display device according to the present embodiment controls the displaying part to adjust an emission angle of display light from the displaying part toward the reflection member to an emission angle corresponding to a detection eye point or a detection eye box to project the display light reflected by the reflection member at a viewpoint position corresponding to the detection eye point or the detection eye box on the projection target part, making it possible to provide clear virtual image display in accordance with the eye point of the occupant. Furthermore, the vehicle display device according to the present embodiment does not use a diffusion member having a greater diffusion angle, but is able to control the displaying part to diffuse light at a wide angle in accordance with a position of each of a plurality of eye points or a plurality of eye boxes. Thus, there is a less decrease in luminance along with a change of each of the eye points or eye boxes, as can be seen in the conventional vehicle display devices, as well as there is no need to increase the output of the light sources. Therefore, the vehicle display device makes it possible to suppress an increase in power consumption. As described above, the vehicle display device according to the present embodiment makes it possible to suppress an increase in power consumption, and to provide clear virtual image display in accordance with the eye point. 
     Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.