JP6432540B2 - Head-up display device - Google Patents

Description

  The present invention relates to a head-up display device (hereinafter, abbreviated as a HUD device) that is mounted on a moving body and displays a virtual image so that an image can be viewed by an occupant.

  2. Description of the Related Art Conventionally, a HUD device that is mounted on a moving body and displays a virtual image so that an image can be visually recognized by a passenger is known. The device disclosed in Patent Document 1 includes a projection unit that projects display light, and a plate-shaped light transmitting plate that is disposed on an optical path from the projection unit to the projection member and transmits the display light.

  This translucent plate is formed by rolling in the manufacturing process, and the refractive index in the rolling direction is different from the refractive index in the direction perpendicular to the rolling direction.

JP2015-31924A

  In Patent Document 1, it is considered that the brightness of the virtual image is adjusted by arranging the plate thickness direction along the optical axis, and rotating the translucent plate around the optical axis to adjust the rotation angle.

  However, even if such a translucent plate is rotated as described above, the azimuth angle of polarized light can be adjusted according to the rotation angle, but the phase difference that acts on the display light cannot be adjusted. There was a limit to the adjustment range. For this reason, there are cases where a virtual image that is sufficiently easy to visually recognize cannot be realized under the restriction of being mounted on the moving body.

  The present invention has been made in view of the problems described above, and an object thereof is to provide a HUD device capable of realizing a virtual image that is easy to visually recognize.

The present invention is a head-up display device that is mounted on a movable body (1) and displays a virtual image (VI) that can be visually recognized by an occupant by reflecting display light on a projection member (3) of the movable body,
A projection unit (20) for projecting display light;
A plate-shaped light transmitting plate (50, 250, 350, 450) disposed on the optical path (OP) from the projection unit to the projection member and having translucency,
The translucent plate has a refractive index in the plate thickness direction (VD), a refractive index in the first extending direction (MD) perpendicular to the plate thickness direction, and perpendicular to the plate thickness direction and the first extending direction. The refractive index of the second extending direction (TD) is different from each other, and the thickness direction is inclined with respect to the optical axis (OA) .
A virtual ellipsoid that passes through the optical axis in the center and takes the principal axis in the plate thickness direction, the first extending direction, and the second extending direction, and the length of each principal axis is half the refractive index in each direction. If the refractive index ellipsoid (RIE) is defined as
The absolute value of the difference in length between the major axis (MAA) and minor axis (MIA) in the virtual ellipsoidal section (SE) that passes through the center of the refractive index ellipsoid and is perpendicular to the optical axis is It is larger than the absolute value of the difference between the refractive index in the first extending direction and the refractive index in the second extending direction .

  According to such an invention, on the optical path from the projection unit to the projection member, the plate-like translucent plate having translucency is arranged. The translucent plate has a refractive index in the plate thickness direction, a refractive index in the first extending direction, and a refractive index in the second extending direction, so that the display light projected on the projection unit is A phase difference can be generated before reaching the projection member. Furthermore, since the translucent plate is disposed with the plate thickness direction inclined with respect to the optical axis, a phase difference corresponding to the inclination can be realized by utilizing a difference in refractive index in the plate thickness direction. By such an inclined arrangement of the light-transmitting plate, for example, at the design stage, it is possible to adjust both the azimuth angle of polarization and the ellipticity of polarization in display light, so that the HUD device can be mounted on a moving body. Even underneath, the degree of reflection on the projection member can be improved to provide a virtual image that is easy to view.

  In addition, the code | symbol in a parenthesis is not what was intended to limit the content of invention, only to illustrate the structure which respond | corresponds in embodiment mentioned later in order to make an understanding of description content easy.

It is a figure which shows the mounting state to the vehicle of the HUD apparatus in 1st Embodiment. It is a figure which shows schematic structure of the HUD apparatus in 1st Embodiment. It is a schematic diagram which shows the projection part in 1st Embodiment. It is a figure for demonstrating the longitudinal direction and transversal direction of the screen of the liquid crystal panel in 1st Embodiment. It is a graph which shows the relationship between the inclination angle of the plate | board thickness direction with respect to an optical axis, and the phase difference which acts on display light. It is a figure for demonstrating an example of arrangement | positioning of the translucent board in 1st Embodiment. In the first embodiment, the relationship between the rotation angle and the relative brightness of the virtual image when the light transmission plate is rotated according to FIG. 6B in the state where the light transmission plate is rotated according to FIG. It is a graph. In a comparative example, it is a graph which shows the relationship between a rotation angle and the relative luminance of a virtual image. In a comparative example, it is a figure for demonstrating the effect | action of a translucent board. It is a figure for demonstrating an example of arrangement | positioning of the translucent board in 1st Embodiment. In the first embodiment, when the light transmitting plate is rotated according to FIGS. 9A and 9B, the rotation angle when the light transmitting plate is rotated according to FIG. It is a graph which shows the relationship. It is a figure for demonstrating the refractive index ellipsoid in 1st Embodiment. It is a figure corresponding to FIG. 2 in 2nd Embodiment. It is a figure corresponding to FIG. 2 in 3rd Embodiment. It is a figure corresponding to FIG. 2 in 4th Embodiment. FIG. 9 is a diagram corresponding to FIG. 2 in Modification 1.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In addition, the overlapping description may be abbreviate | omitted by attaching | subjecting the same code | symbol to the corresponding component in each embodiment. When only a part of the configuration is described in each embodiment, the configuration of the other embodiment described above can be applied to the other part of the configuration. In addition, not only combinations of configurations explicitly described in the description of each embodiment, but also the configurations of a plurality of embodiments can be partially combined even if they are not explicitly specified unless there is a problem with the combination. .

(First embodiment)
As shown in FIG. 1, the HUD device 100 according to the first embodiment of the present invention is mounted on a vehicle 1 that is a kind of moving body, and is accommodated in an accommodation portion 2 a of an instrument panel 2. The HUD device 100 projects an image on a windshield 3 as a projection member of the vehicle 1. When the image display light is reflected by the windshield 3, the HUD device 100 displays a virtual image VI that can be visually recognized by an occupant seated on the seat 4 in the vehicle 1. That is, the display light reflected by the windshield 3 reaches the occupant's eyes in the vehicle 1 and the occupant perceives the display light as a virtual image VI. And a crew member can recognize various information by virtual image VI. Examples of the various information displayed as the virtual image VI include vehicle state values such as vehicle speed and fuel remaining amount, or navigation information such as road information and visibility assistance information.

  The windshield 3 of the vehicle 1 is formed in a translucent plate shape by glass or synthetic resin. In the windshield 3, the surface on the indoor side forms a reflecting surface 3a on which an image is projected in a concave shape or a flat shape.

  The shape of the windshield 3 and the relative positions of the housing portion 2a of the instrument panel 2 and the seat 4 with respect to the windshield 3 are generally set by the vehicle manufacturer based on the use or design of the vehicle 1 and the like. . Here, the display light reflected by the windshield 3 is applied to a viewing area EB that is set so as to overlap with an eyelid (for details, refer to JIS D0021: 1998), which is an area where there is a high possibility of the presence of an occupant's eye seated on the seat 4. To reach, the HUD device 100 is optically designed. Here, the visual recognition area EB is a spatial area in which the virtual image VI displayed by the HUD device is visible.

  Therefore, mounting conditions such as the incident angle of the display light on the windshield 3 vary depending on the vehicle type of the vehicle 1 to be mounted and are restricted.

  A specific configuration of such a HUD device 100 will be described below with reference to FIGS. As shown in FIG. 2, the HUD device 100 includes a housing member 10, a projection unit 20, a plane mirror 30, a concave mirror 40, and a light transmitting plate 50.

  The housing member 10 is a member that is formed in a box shape having a light shielding property by, for example, a synthetic resin, and houses the projection unit 20, the plane mirror 30, the concave mirror 40, and the translucent plate 50. The housing member 10 has a window-shaped window portion 12 at a location facing the windshield 3.

  As shown in detail in FIG. 3, the projection unit 20 includes a light source 22, a condenser lens 24, a projection lens 26, and a liquid crystal panel 28. For example, the projection unit 20 is formed by housing them in a box-shaped casing 20 a. Yes.

  The light source 22 is, for example, a plurality of light emitting diode elements, and is disposed on the light source circuit board 22a. The light source 22 is electrically connected to a power source through a wiring pattern on the light source circuit board 22a. The light source 22 emits light source light with a light emission amount corresponding to a current amount when energized. Thereby, the light source 22 projects the light source light toward the condenser lens 24. More specifically, the light source 22 emits pseudo white light, for example, by covering a blue light emitting diode with a phosphor.

  The condensing lens 24 is a lens array that is disposed between the light source 22 and the projection lens 26 and in which translucent convex lens elements made of synthetic resin or glass are arranged in accordance with the number of light emitting diodes. The condensing lens 24 condenses the light source light from the light source and emits it toward the projection lens 26.

  The projection lens 26 is disposed between the condenser lens 24 and the liquid crystal panel 28, and is a translucent Fresnel lens made of synthetic resin or glass. The projection lens 26 condenses the light source light from the condenser lens 24 and emits it toward the liquid crystal panel 28.

  The liquid crystal panel 28 is a liquid crystal panel using a thin film transistor (TFT), for example, and is an active matrix type liquid crystal panel formed from a plurality of liquid crystal pixels arranged in a two-dimensional direction. In the liquid crystal panel 28, a pair of polarizing plates and a liquid crystal layer sandwiched between the pair of polarizing plates are stacked. The polarizing plate has a property of transmitting light polarized along a predetermined direction and shielding light polarized along a direction perpendicular to the predetermined direction, and the pair of polarizing plates have the predetermined direction substantially orthogonal to each other. Be placed. The liquid crystal layer can rotate the polarization direction of light incident on the liquid crystal layer in accordance with the applied voltage by applying a voltage for each liquid crystal pixel.

  Therefore, the liquid crystal panel 28 controls the transmittance of the light source light for each liquid crystal pixel, so that the projection unit 20 can project image display light. Here, the display light is projected from the projection unit 20 as light that is linearly polarized in the direction PAD of the polarization axis as the predetermined direction of the polarizing plate on the exit side. In the present embodiment, the screen of the liquid crystal panel 28 is formed in a rectangular shape having the longitudinal direction LD and the lateral direction SD, and the polarization axis direction PAD is set to a direction that forms 135 degrees with respect to the longitudinal direction LD. ing. The display light projected on the projection unit 20 enters the plane mirror 30.

  The flat mirror 30 is formed by depositing aluminum as the reflecting surface 32 on the surface of a base material made of synthetic resin or glass. The reflection surface 32 is formed in a smooth flat shape. The plane mirror 30 reflects the display light from the projection unit 20 toward the concave mirror 40.

  The concave mirror 40 is formed by depositing aluminum as the reflecting surface 42 on the surface of a base material made of synthetic resin or glass. The reflecting surface 42 is formed in a smooth curved surface as a concave surface in which the center of the concave mirror 40 is recessed. The concave mirror 40 reflects the display light from the plane mirror 30. The display light reflected by the concave mirror 40 is directed to the windshield 3 through the translucent plate 50.

  Thus, an optical path OP from the projection unit 20 to the windshield 3 is configured. The translucent plate 50 is disposed on the optical path OP and is formed in a flat plate shape having translucency. In particular, the translucent plate 50 of this embodiment is disposed so as to close the window 12 of the housing member 10 on the optical path between the concave mirror 40 and the windshield 3.

  In such a translucent plate 50, a plate thickness direction VD can be defined as a direction along the normal direction of the surface. A first extending direction MD perpendicular to the plate thickness direction VD can be defined. Furthermore, a second extending direction TD perpendicular to the plate thickness direction VD and the first extending direction MD can be defined.

The light transmitting plate 50 is made of synthetic resin such as polycarbonate resin or acrylic resin. The translucent plate 50 of the present embodiment has a plate thickness that is a dimension along the plate thickness direction VD, for example, 0.5 mm, and the entire plate thickness is substantially the same. The translucent plate 50 has a refractive index N _VD in the plate thickness direction VD, a refractive index N MD in the first extending direction _MD , and a refractive index N _{TD in} the second extending direction TD different from each other. Specifically, in this embodiment, the refractive index N _VD = 1.5845 in the plate thickness direction VD, the refractive index N _MD = 1.5853 in the first extending direction MD, and the refractive index N in the second extending direction TD. _TD = 1.5851. These refractive indexes N _VD , N _MD , and N _TD are refractive indexes for light having a wavelength of 580 nm.

  At the same time, the translucent plate 50 is disposed with the plate thickness direction VD inclined with respect to the optical axis OA. In particular, in the present embodiment, the translucent plate 50 is fixedly arranged in a state where the plate thickness direction VD is inclined with respect to the optical axis OA. Here, the optical axis OA in the present embodiment refers to the light beam obtained by tracing light rays from the center pixel of the screen to the center of the viewing area EB among the liquid crystal pixels arranged in the two-dimensional direction on the liquid crystal panel 28. It is a route. Particularly in the present embodiment, the optical axis OA is a path of a principal ray emitted perpendicularly to the screen from the pixel that is the center of the screen.

  Further, as shown in FIG. 4, on the virtual plane IP perpendicular to the optical axis OA, a longitudinal corresponding direction RLD corresponding to the longitudinal direction LD of the screen and a short corresponding direction RSD corresponding to the lateral direction SD of the screen Define. The longitudinal corresponding direction RLD is a direction obtained by projecting on the virtual plane IP along the optical axis OA using the longitudinal direction LD on the screen as a vector. The short correspondence direction RSD is a direction obtained by projecting the short direction SD on the screen onto the virtual plane IP along the optical axis OA as a vector. In other words, when the direction of the optical axis OA changes due to reflection by the plane mirror 30 and the concave mirror 40, the direction corresponding to the longitudinal direction RLD and the direction corresponding to the short side RSD also change accordingly.

As shown in FIG. 2, the display light is transmitted through the light transmitting plate 50 provided with the plate thickness direction VD inclined, for example, along the optical axis OA. At this time, since the refractive indexes N _VD , N _MD , and N _{TD in the} directions VD, MD, and TD are different, a phase difference is generated in the display light, the azimuth angle of the polarization is rotated, and the ellipticity of the polarization is Will change. By adjusting the polarization state of the display light according to the incident angle to the windshield 3, the brightness of the virtual image VI visually recognized by the occupant is adjusted.

  Hereinafter, the relationship between the inclination of the light transmitting plate 50 and its brightness adjustment function will be described in detail with reference to FIGS.

  FIG. 5 plots the relationship between the tilt angle when the light transmitting plate 50 is rotated about the first extending direction MD (see FIG. 6A) and the phase difference exerted on the display light. Yes. According to this, when the tilt angle of the light transmitting plate 50 is 0 degree (that is, the state in which the plate thickness direction VD is along the optical axis OA), the phase difference is less than 150 nm in terms of distance. When the tilt angle is increased, the phase difference gradually increases from around 20 degrees, and at a tilt angle of 45 degrees, a phase difference greater than 200 nm can be obtained in terms of distance.

  The phase difference in FIG. 5 is a phase difference with respect to light having a wavelength of 580 nm. Therefore, when the tilt angle is 0 degree, the translucent plate 50 functions as a substantially quarter-wave plate and increases the tilt angle. As a result, the function of the half-wave plate can be approached.

  Next, FIG. 7 shows the rotation angle when the translucent plate is rotated with the plate thickness direction VD as the rotation axis in the state of the inclination angle of 45 degrees as described above (see FIG. 6B), and the visual recognition. The relationship with the relative luminance of the virtual image VI is plotted. According to this, when the rotation angle of the translucent plate 50 is about 150 degrees, the relative luminance is 15685, which is the maximum value. Further, when the rotation angle of the translucent plate 50 is about 30 degrees, the relative luminance is 2629, which is the minimum value. The rotation angle of the translucent plate 50 is based on the longitudinal corresponding direction RLD. That is, when the first extending direction MD coincides with the longitudinal corresponding direction RLD, it is 0 degree.

  As a comparative example, FIG. 8 shows the relationship between the rotation angle when the translucent plate is rotated about the plate thickness direction VD and the relative luminance of the visible virtual image VI in a state where the inclination angle is 0 degree. It is plotted. According to this, when the rotation angle of the translucent plate is 67.5 degrees or 157.5 degrees, the relative luminance is 14950, which is the maximum value. Further, when the rotation angle of the translucent plate 50 is about 20 degrees or about 110 degrees, the relative luminance is 5051, which is the minimum value.

  More specifically, as shown in FIG. 9, the reflection cross section WRP of the windshield 3 is arranged along a direction that forms 90 degrees with respect to the longitudinal corresponding direction RLD. Therefore, if the display light after passing through the light transmitting plate 50 is polarized light having a large amount of components in the direction ND (that is, 0 degree) perpendicular to the reflection cross section WRP, the reflectance of the display light in the windshield 3 is increased. The brightness of the virtual image VI can be increased. For this reason, in the comparative example, the first extending direction MD is set to 67.5 degrees or 157.5 degrees which is an intermediate between the angle of the polarization axis direction PAD of the projection unit and the angle ND perpendicular to the reflection cross section WRP. When set, it is considered that the luminance can be increased. However, in the comparative example, since a sufficient phase difference was not given to the display light, the maximum value of the relative luminance is small compared to the present embodiment.

  From the comparison of the simulation results, it can be seen that when the thickness direction VD of the light transmission plate 50 is inclined with respect to the optical axis OA, the adjustment range is wider and the luminance adjustment effect by the light transmission plate 50 is larger. .

  In the above description, the first extending direction MD that can be defined based on the translucent plate 50 is used as a rotation axis, and the plate thickness direction VD of the translucent plate 50 is disposed in an inclined state with respect to the optical axis OA. In addition to this, as shown in FIG. 10, the plate thickness direction VD may be arranged in an inclined state with respect to the optical axis OA by a rotation axis defined based on the image of the projection unit 20.

  First, from the state where the plate thickness direction VD is along the optical axis OA and the first extending direction MD is along the longitudinal corresponding direction RLD, the longitudinal corresponding direction RLD is rotated by α degrees (FIG. 10 ( a)). Next, the translucent plate 50 is rotated by β degrees about the short side corresponding direction RSD as a rotation axis (see FIG. 10B). Thus, the plate thickness direction VD of the translucent plate 50 is inclined with respect to the optical axis OA.

  In a state where α is 21 degrees and β is −41 degrees, the rotation angle when the translucent plate 50 is rotated about the plate thickness direction VD (see FIG. 10C) The relationship with the relative luminance of the virtual image VI that is visually recognized is plotted in FIG. According to this, when the rotation angle of the translucent plate 50 is about 150 degrees, the relative luminance is 19019, which is the maximum value.

  7 and 11, it should be noted that the light transmitting plate 50 is not necessarily optimal so that the relative luminance takes the maximum value. This is because the relative luminance in FIGS. 5, 7, and 11 is luminance when the occupant with naked eyes visually recognizes the virtual image VI, and there is room for considering the visibility of the virtual image VI by the occupant wearing polarized sunglasses. That is, the translucent plate 50 may be arranged in a state of being deviated from the maximum value so that the visibility of the occupant wearing the naked eye and the occupant wearing the polarized sunglasses is balanced.

The arrangement of the translucent plate 50 in the present embodiment will be described in more detail. Here, as shown in FIG. 12, it is a virtual ellipsoid whose optical axis OA passes through the center, and the main axis is taken in the plate thickness direction VD, the first extending direction MD, and the second extending direction TD. A refractive index ellipsoid RIE is defined in which the length of each is a half value of the refractive indexes N _VD , N _MD , N _{TD in} the corresponding directions VD, MD, TD. Then, a virtual elliptical cut surface SE that passes through the center of the refractive index ellipsoid RIE and is a cross section perpendicular to the optical axis OA is defined.

として表される。 In the present embodiment, the absolute value of the difference in length between the major axis MAA and the minor axis MIA on the elliptical cut surface SE is the refractive index N _{MD in} the first extending direction MD and the refractive index N in the second extending direction TD. _The translucent plate 50 is disposed so as to be larger than the absolute value of the difference from _TD . This arrangement condition can be rewritten using the angles α and β described above. First, the rotation matrix by rotation of angles α and β is

Represented as:

と表される。ただし、

である。数２において、左辺が楕円切断面ＳＥにおける長軸ＭＡＡと短軸ＭＩＡとの長さの差の絶対値であり、右辺が第１延設方向ＭＤの屈折率Ｎ_ＭＤと第２延設方向ＴＤの屈折率Ｎ_ＴＤとの差の絶対値である。 Using each component of this matrix rotation, the placement condition is

It is expressed. However,

It is. In Equation 2, the left side is the absolute value of the difference in length between the major axis MAA and the minor axis MIA in the elliptical cut surface SE, and the right side is the refractive index NMD of the first extending direction _MD and the second extending direction TD. Is the absolute value of the difference from the refractive index _NTD .

(Function and effect)
The operational effects of the first embodiment described above will be described below.

According to the first embodiment, a plate-like translucent plate 50 having translucency is arranged on the optical path OP from the projection unit 20 to the windshield 3. Transparent plate 50 has a refractive index _{N VD} in the thickness direction VD, and the refractive index _{N MD} of the first extension direction MD, and a refractive index _{N TD} of the second extension direction TD, because they were different from each other The display light projected on the projection unit 20 may cause a phase difference before reaching the windshield 3. Further, the transparent plate 50 from being disposed to be inclined to the thickness direction VD with respect to the optical axis OA, by utilizing a difference in refractive index N _VD in the thickness direction VD, the phase difference corresponding to the inclination Can be realized. By such an inclined arrangement of the translucent plate 50, for example, at the design stage, it is possible to adjust both the azimuth angle of polarization and the ellipticity of polarization in the display light, so that the HUD device 100 is mounted on the vehicle 1. Even under such restrictions, it is possible to provide a virtual image VI that is easy to view by improving the degree of reflection at the windshield 3.

Further, according to the first embodiment, the absolute value of the difference in length between the major axis MAA and the minor axis MIA in the virtual elliptical cutting plane SE is the refractive index NMD in the first extending direction _MD and the second extending length. It is larger than the absolute value of the difference between the refractive index N _TD direction TD. According to such an arrangement of the translucent plate 50, the phase difference acting on the display light can be made larger than when the plate thickness direction VD is arranged along the optical axis OA. Therefore, even under the restrictions of being mounted on the vehicle 1, it is possible to reliably improve the state of reflection by the windshield 3 and provide a virtual image VI that is easy to visually recognize.

  Moreover, according to the flat light-transmitting plate 50 of the first embodiment, it is easy to apply the same adjustment action to the entire display light, so that the luminance unevenness of the virtual image VI can be suppressed.

  In addition, according to the first embodiment, the housing member 10 that houses the projection unit 20 is further provided, and the translucent plate 50 is disposed so as to close the window 12 of the housing member 10. Since the translucent plate 50 can prevent foreign matter from entering the inside of the apparatus 100 from the outside, it is possible to maintain the virtual image VI that is easy to visually recognize for a long time while suppressing an increase in the number of parts. .

(Second Embodiment)
As shown in FIG. 13, the second embodiment of the present invention is a modification of the first embodiment. The second embodiment will be described with a focus on differences from the first embodiment.

  The translucent plate 250 of the second embodiment is provided so as to close the window 12 of the housing member 10 on the optical path between the concave mirror 40 and the windshield 3, as in the first embodiment.

  The translucent plate 250 of the second embodiment is formed in a curved plate shape. Specifically, the translucent plate 250 is curved in a concave shape so as to enter the inside of the HUD device 200. The said curve is a cylindrical curve, for example, and the curvature radius in this curve is set to 150 cm, for example. The entire light-transmitting plate 250 has substantially the same thickness.

  Also in the second embodiment, the optical axis OA and the translucent plate 250 are fixedly arranged in a state where the thickness direction VD is inclined with respect to the optical axis OA. In the case of such a curved plate-shaped translucent plate 250, there is a possibility that a portion where the plate thickness direction VD coincides with the direction of the optical axis OA exists outside the optical axis OA. However, if the plate thickness direction VD is inclined at the location where the optical axis OA and the translucent plate 250 intersect, the translucent plate 250 can exert a corresponding action on the display light.

  According to such a second embodiment, the curved surface-shaped translucent plate 250 is arranged to be inclined with respect to the optical axis OA, so that external light such as sunlight that can enter from the outside of the device 100 to the inside can be obtained. Since the light can be reflected by the translucent plate 250 so as not to reach the occupant side, it is possible to realize a phase difference corresponding to the inclination while suppressing deterioration of the contrast of the virtual image VI due to external light. Therefore, it is possible to provide a virtual image VI that is easy to visually recognize.

(Third embodiment)
As shown in FIG. 14, the third embodiment of the present invention is a modification of the second embodiment. The third embodiment will be described with a focus on differences from the second embodiment.

  Similar to the first and second embodiments, the light transmitting plate 350 of the third embodiment is disposed on the optical path between the concave mirror 40 and the windshield 3 so as to close the window 12 of the housing member 10. . Here, the HUD device 300 further includes a polarizing plate 352 bonded to the translucent plate 350 as a visual restriction unit.

  The polarizing plate 352 closes the window portion 12 together with the translucent plate 350 while being bonded to the translucent plate 350. In particular, the polarizing plate 352 of the present embodiment is an absorptive polarizing plate formed by adding iodine, which is a dichroic dye, to polyvinyl alcohol. The polarizing plate 352 has a transmission axis and an absorption axis orthogonal to each other depending on the orientation direction of iodine molecules. The polarizing plate 352 has a property of transmitting light polarized along the transmission axis and absorbing light polarized along the absorption axis.

  Here, the polarizing plate 352 is disposed, for example, on the concave mirror side of the translucent plate 350, with its transmission axis aligned with the polarization direction (that is, the polarization axis direction PAD) in the linearly polarized display light projected from the projection unit 20. ing. With such an arrangement, the polarizing plate 352 allows most of the display light to pass through the light transmitting plate 350 as it is, while restricting the inside of the housing member 10 from being visually recognized from the outside. Further, the polarizing plate 352 blocks part of external light such as sunlight that enters the HUD device 300 from the outside of the vehicle 1 through the windshield 3, for example.

  According to the third embodiment, the window 12 is closed together with the light transmissive plate 350 in a state where the visual restriction portion is bonded to the light transmissive plate 350, and the inside of the housing member 10 is restricted from being visually recognized from the outside. According to this, the display light collectively transmits through the visual restriction part and the translucent plate 350, so that it is difficult to look into the inside while suppressing loss of luminance.

  Further, according to the third embodiment, the visual restriction part is the polarizing plate 352. According to this, by allowing the linearly polarized projection light to pass through the polarizing plate 352, it is possible to make it difficult to look inside the apparatus 300 while reliably suppressing loss of luminance.

(Fourth embodiment)
As shown in FIG. 15, the fourth embodiment of the present invention is a modification of the second embodiment. The fourth embodiment will be described with a focus on differences from the second embodiment.

  In the HUD device 400 of the fourth embodiment, the translucent plate 450 closes the window 12 of the housing member 10 on the optical path between the concave mirror 40 and the windshield 3 as in the first to third embodiments. Is arranged.

  In contrast to the uncolored translucent plates 50 and 250 of the first and second embodiments, the translucent plate 450 of the fourth embodiment is colored while having translucency. In the present embodiment, the translucent plate 450 is colored, for example, in a smoke tone. It is preferable that the hue in coloring is the same system as the hue of the instrument panel 2, for example.

  Further, as a coloring method of the light transmitting plate 450, a method such as coloring the light transmitting plate 450 base material with a dye or printing on the surface of the light transmitting plate 450 may be employed.

  According to the fourth embodiment, the colored translucent plate 450 can make it difficult to look inside the device 400 while suppressing an increase in the number of components.

(Other embodiments)
Although a plurality of embodiments of the present invention have been described above, the present invention is not construed as being limited to these embodiments, and various embodiments and combinations can be made without departing from the scope of the present invention. Can be applied.

  Specifically, as a first modification, the translucent plate 50 may not cover the window 12 of the housing member 10. As an example of this, in FIG. 16, the translucent plate 50 is disposed on the optical path between the projection unit 20 and the plane mirror 30 with the plate thickness direction VD inclined with respect to the optical axis OA.

  As a second modification, the translucent plate 50 is not limited to the one that is fixedly arranged in the state where the thickness direction VD is inclined with respect to the optical axis OA. As an example of this, the HUD device 100 may further include a movable mechanism that changes the thickness direction VD of the translucent plate 50 with respect to the optical axis OA. For example, the visibility variation of the virtual image VI due to the brightness error of the display light of the projection unit 20 and the positional relationship error that may occur in the manufacturing process can be adjusted by the movable mechanism.

  As a third modified example related to the third embodiment, the polarizing plate 352 used as the visual restriction part may be disposed closer to the windshield 3 than the translucent plate 350.

  As a fourth modified example related to the third embodiment, the polarizing plate 352 used as the visual restriction part may be a reflective polarizing plate. In addition to the polarizing plate 352, a film-like half mirror may be employed as the visual restriction part.

  As a fifth modification, the projection unit 20 may employ a method other than the method using the liquid crystal panel 28. As an example of this, the projection unit 20 may be a method of projecting the laser beam constituting the pixels of the image as display light by scanning the laser beam and drawing an image on the screen. In this case, the optical axis OA is a path of the laser beam that constitutes the pixel at the center of the image.

  As a sixth modification, the present invention may be applied to various moving bodies (transport equipment) such as ships or airplanes other than the vehicle 1.

  100, 200, 300, 400 HUD device, 1 vehicle (moving body), 3 windshield (projection member), 10 housing member, 12 window portion, 20 projection portion, 50, 250, 350, 450 translucent plate, 352 polarized light Board (visual restriction part), VI virtual image, OP optical path, OA optical axis

Claims (7)

A head-up display device that is mounted on a moving body (1) and displays a virtual image (VI) that can be seen by an occupant by reflecting display light on a projection member (3) of the moving body,
A projection unit (20) for projecting the display light;
A plate-shaped translucent plate (50, 250, 350, 450) disposed on an optical path (OP) from the projection unit to the projection member and having translucency,
The translucent plate includes a refractive index in a plate thickness direction (VD), a refractive index in a first extending direction (MD) perpendicular to the plate thickness direction, the plate thickness direction, and the first extending direction. The second extending direction (TD) perpendicular to the refractive index is different from each other, and the plate thickness direction is inclined with respect to the optical axis (OA) ,
A virtual ellipsoid through which the optical axis passes in the center, each having a main axis in the plate thickness direction, the first extending direction, and the second extending direction, and corresponding lengths of the main axes; Defining a refractive index ellipsoid (RIE) with half the refractive index in the direction,
The absolute value of the difference in length between the major axis (MAA) and the minor axis (MIA) in the virtual ellipsoidal section (SE) that passes through the center of the refractive index ellipsoid and is perpendicular to the optical axis is The head-up display device having an absolute value larger than the absolute value of the difference between the refractive index in the first extending direction and the refractive index in the second extending direction . The head-up display device according to claim 1, wherein the translucent plate has a curved plate shape. The head-up display device according to claim 1, wherein the translucent plate has a flat plate shape. A storage member (10) for storing the projection unit;
The housing member has a window-shaped window portion (12) at a location facing the projection member,
The transparent plate is a head-up display device according to any one of claims 1 to 3 disposed so as to close the window. While being bonded to the transparent plate, the window closes together with the transparent plate, in claim 4 in which the interior of said housing member further comprises visual regulating portion for regulating to be viewed from outside the (352) The head-up display device described. The projection unit projects the display light as linearly polarized light,
The head-up display device according to claim 5 , wherein the visual restriction part is a polarizing plate. The head-up display device according to claim 4 , wherein the translucent plate is colored.

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