JP6179463B2 - Projection member and head-up display device - Google Patents

Description

The present invention relates to a projection member and the head-up display device (hereinafter, abbreviated to HUD device).

2. Description of the Related Art Conventionally, a projection member on which a virtual image is projected is known in 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 using light source light. The projection member disclosed in Patent Document 1 has a first light transmitting plate that maintains a polarization state on the front side facing the occupant, and a second surface on the back side opposite to the front side. A second translucent plate that maintains the state, and a retardation plate that is sandwiched between the first translucent plate and the second translucent plate and has a fast axis and a slow axis that delays the phase with respect to the fast axis And. As the light source light, s-polarized light is incident on the first surface obliquely along the incident surface . The retardation plate is a half-wave plate that rotates the polarization direction by 90 °.

Japanese Patent Laid-Open No. 10-96874

  In the projection member disclosed in Patent Document 1, the light source light transmitted through the retardation plate becomes a p-polarized component, so that the reflectance on the second surface on the back side is higher than the reflectance on the first surface on the front side. By making it smaller, it is possible to suppress double images. However, since the reflectance of the second surface on the back side is reduced, the brightness of the virtual image is lowered, and thus the visibility of the virtual image cannot be sufficiently improved.

  In addition, when the occupant is wearing polarized sunglasses whose blocking axis is generally fixed in the horizontal direction, the virtual image cannot be sufficiently visually recognized only by the s-polarized light source light.

The present invention was made in view of the problems described above, and an object thereof is to provide a projection member and HUD equipment enhance the visibility of the virtual image.

A projection member as one of the disclosed inventions is mounted on a moving body (1), and an image is projected on a head-up display device (10) that uses a light source light to display a virtual image so that the image can be visually recognized by an occupant. A first light transmitting plate (42, 242) having a first surface (42a, 242a) on the front side facing the occupant and maintaining the polarization state, and a projection member on the back side opposite to the front side. The second translucent plate (44, 244) having two surfaces (44a, 244a) and maintaining the polarization state is sandwiched between the first translucent plate and the second translucent plate, and a fast axis ( 46a) and a retardation plate (46) having a slow axis (46b) for delaying the phase with respect to the fast axis, and the light source light is obliquely incident on the first surface along the incident surface (PI). And including both s-polarization component and p-polarization component, and the slow axis of the retardation plate , Characterized in that inclined to the plane of incidence.

According to such an invention, the light source that is incident obliquely along the incident surface on the first surface on the front side of the first light transmitting plate that maintains the polarization state and includes both the s-polarized component and the p-polarized component. On the first surface on the front side, light is reflected around the s-polarized component and passes through the first light-transmitting plate around the p-polarized component. Here, the phase difference plate is sandwiched between the first light transmission plate and the second light transmission plate in a state where the slow axis is inclined with respect to the incident surface . By the action of the retardation plate, the polarization direction of the light source light centered on the p-polarized light component transmitted through the first light transmission plate is rotated to the s-polarization side. Further, according to the second light transmitting plate having the second surface on the back side and maintaining the polarization state, the light source light transmitted through the phase difference plate and rotated to the s polarization side has a reflectance on the second surface. Since it is reflected to the front side in a high state, the brightness of the virtual image visually recognized by the occupant can be increased. Therefore, the visibility of the virtual image can be improved.

Further, the light source light reflected by the second surface on the back side is transmitted again through the phase difference plate, and the polarization direction of the light source light has a slow axis that is inclined with respect to the incident surface that is the direction of p-polarized light. By the action of the phase difference plate, it is rotated again toward the direction of p-polarized light. According to this, even when the occupant is wearing general polarized sunglasses, the light source light that reflects the first surface on the front side and centered on the s-polarized component and the second surface on the back side is reflected. Since both of the light sources centering on the p-polarized component are incident on general polarized sunglasses, a virtual image can be visually recognized.

A head-up display device as another disclosed invention is mounted on a moving body (1) and projects an image on a projection member (40, 240) to display a virtual image so that the occupant can visually recognize the image. The head-up display device includes a light source (12) that emits light source light and an optical system (14) that causes the light source light to enter the projection member. The projection member has a first surface on the front side facing the occupant ( 42a, 242a) having a first light transmitting plate (42, 242) for maintaining the polarization state and a second surface (44a, 244a) on the back side opposite to the front side to maintain the polarization state. The second light transmission plate (44, 244) and the slow axis (46a) and the slow axis that delays the phase with respect to the fast axis, sandwiched between the first light transmission plate and the second light transmission plate. 46b) retardation plate (46, 246) With the door, the optical system along the incidence surface inclined with respect to the slow axis (PI), the source light is incident obliquely on the first surface, and to include both s-polarized light component and p-polarized light component It is made to inject into.

According to such an invention, the light source light emitted from the light source is incident obliquely on the first surface along the incident surface by the optical system, and is incident so as to include both the s-polarized component and the p-polarized component. Let Such light source light is reflected around the s-polarized component on the first surface on the front side and passes through the first translucent plate around the p-polarized component. Here, the phase difference plate is sandwiched between the first light transmission plate and the second light transmission plate in a state where the slow axis is inclined with respect to the incident surface . By the action of the retardation plate, the polarization direction of the light source light centered on the p-polarized light component transmitted through the first light transmission plate is rotated to the s-polarization side. Further, according to the second light transmitting plate having the second surface on the back side and maintaining the polarization state, the light source light transmitted through the phase difference plate and rotated to the s polarization side has a reflectance on the second surface. Since it is reflected to the front side in a high state, the brightness of the virtual image visually recognized by the occupant can be increased. Therefore, the visibility of the virtual image can be improved.

Further, the light source light reflected by the second surface on the back side is transmitted again through the phase difference plate, and the polarization direction of the light source light has a slow axis that is inclined with respect to the incident surface that is the direction of p-polarized light. By the action of the phase difference plate, it is rotated again toward the direction of p-polarized light. According to this, even when the occupant is wearing general polarized sunglasses, the light source light that reflects the first surface on the front side and centered on the s-polarized component and the second surface on the back side is reflected. Since both of the light sources centering on the p-polarized component are incident on general polarized sunglasses, a virtual image can be visually recognized.

  In addition, the code | symbol in a parenthesis is only what exemplifies the structure corresponding to embodiment mentioned later, in order to make an understanding of description content easy, and does not limit the content of invention.

It is a schematic diagram which shows the mounting state to the vehicle of the HUD apparatus and projection member in 1st Embodiment. It is a perspective view which shows the structure of the HUD apparatus in 1st Embodiment. It is a perspective view which shows the structure of the projector in 1st Embodiment. It is a figure which shows partially the cross section of the projection member in alignment with the entrance plane in 1st Embodiment, Comprising: The model for demonstrating the incidence to the 1st surface of light source light, and the reflection in a 1st surface and a 2nd surface FIG. It is a schematic diagram for demonstrating incidence | injection to the 1st surface of the light source light in 1st Embodiment. It is a graph which shows the simulation result in a comparative example. It is a graph which shows the simulation result in a comparative example. It is a graph which shows the simulation result in 1st Embodiment. It is a graph which shows the simulation result in 1st Embodiment. It is a graph which shows the additional simulation result in 1st Embodiment. It is a graph which shows the additional simulation result in 1st Embodiment. It is a figure corresponding to FIG. 1 in 2nd Embodiment. It is a figure corresponding to FIG. 4 in 2nd Embodiment. It is a perspective view which shows the polarized sunglasses in 2nd Embodiment. It is a figure corresponding to FIG.

  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 10 according to the first embodiment of the present invention is mounted on a vehicle 1 which is a kind of moving body and is accommodated in an instrument panel 2. The HUD device 10 projects the image onto the projection member 40 using the light source light, thereby displaying the image in a virtual image so that the occupant can visually recognize the image. That is, the light source light as an image reflected by the projection member 40 reaches the occupant's eye 4 in the vehicle 1 and the occupant perceives the light source light. And a crew member can recognize various information displayed as a virtual image. Examples of various information displayed as the virtual image 3 include vehicle state values such as vehicle speed and fuel remaining amount, or vehicle information such as road information and visibility assistance information.

  As shown in FIGS. 2 and 3, the HUD device 10 includes a light source 12, an optical system 14, and the like. As shown in FIG. 3, the light source 12 is a light emitting element made of, for example, a light emitting diode, and is disposed on the light source circuit board 13. The light source is electrically connected to a control circuit and a power source (not shown) through a wiring pattern (not shown) on the light source circuit board 13. The light source 12 emits light source light with a light emission amount corresponding to a current amount when energized. Thereby, the light source 12 projects the light source light toward the optical system 14. More specifically, the light source 12 realizes pseudo white light emission by covering a blue light emitting diode with a phosphor, for example.

  As shown in FIGS. 2 and 3, the optical system 14 includes a condenser lens 20, a diffusion plate 22, a projection lens 24, a liquid crystal panel 26, a plane mirror 28, and a concave mirror 30. The optical system 14 causes the light source light from the light source 12 to enter the projection member 40.

  Here, the light source 12, the condensing lens 20, the diffusion plate 22, the projection lens 24, and the liquid crystal panel 26 are accommodated in a box-shaped projector case 16a, and constitute the projector 16 shown in FIG.

  The condenser lens 20 is a translucent convex lens made of synthetic resin or glass, and is disposed between the light source 12 and the diffusion plate 22 in the projector 16. The condensing lens 20 condenses the light from the light source 12 and emits it toward the diffusion plate 22.

  The diffusing plate 22 is a translucent or milky white plate formed of a synthetic resin such as polycarbonate in which a light diffusing material is kneaded, and is disposed between the condenser lens 20 and the projection lens 24. The diffusion plate 22 emits light source light, whose luminance uniformity is adjusted by diffusion, toward the projection lens 24.

  The projection lens 24 is a translucent convex lens made of synthetic resin or glass, and is disposed between the diffusion plate 22 and the liquid crystal panel 26. The projection lens 24 condenses the light source light from the diffusion plate 22 and projects it toward the liquid crystal panel 26.

  The liquid crystal panel 26 is a transmissive liquid crystal panel that forms an image by transmitting a part of the light source light incident on the surface on the light source 12 side, and displays the image by emitting light from the surface on the plane mirror 28 side. Specifically, it is a dot matrix type TFT (Thin Film Transistor) liquid crystal panel formed from a plurality of liquid crystal pixels arranged in a two-dimensional direction. The light source light from the projection lens 24 is converted into linearly polarized light having a predetermined polarization direction by passing through a polarizing plate (not shown) in the liquid crystal panel 26. In particular, the predetermined polarization direction in the present embodiment is a direction that forms an angle of 45 ° with respect to the horizontal direction of the image. Here, the polarization direction in this embodiment means the vibration direction of an electric field in linearly polarized light, and the major axis direction of an ellipse in which the amplitude of the electric field is maximum in elliptically polarized light.

  In this way, the projector 16 projects the linearly polarized light source light toward the plane mirror 28.

  As shown in FIG. 2, the plane mirror 28 is formed by depositing aluminum as a reflecting surface 28a on the surface of a base material made of synthetic resin or glass. The reflecting surface 28a is formed on a smooth plane. The plane mirror 28 reflects the light source light from the liquid crystal panel 26 toward the concave mirror 30.

  The concave mirror 30 is formed by evaporating aluminum as the reflecting surface 30a on the surface of a base material made of synthetic resin or glass. The reflecting surface 30a is formed in a smooth curved surface as a concave surface in which the center of the concave mirror 30 is recessed. The concave mirror 30 reflects the light source light from the plane mirror 28 toward the projection member 40.

  The projection member 40 according to the first embodiment is integrally formed with the vehicle 1 in a laminated glass shape as a windshield of the vehicle 1. As shown in an enlarged view in FIG. 4, the projection member 40 includes a first light transmitting plate 42 on the front side, a second light transmitting plate 44 on the back side, and a space between the first light transmitting plate 42 and the second light transmitting plate 44. A phase difference plate 46 sandwiched between the two is provided. Here, the front side in the projection member 40 is the side facing the occupant, and the back side is the opposite side to the front side.

  The first light transmissive plate 42 is formed in a light transmissive plate shape by glass, for example, and is arranged on the front side with respect to the phase difference plate 46 in the projection member 40. The front side of the first light transmission plate 42 forms a first surface 42a as an interface with the space in the vehicle 1 room. In particular, in the first embodiment, a portion where an image is projected on the first surface 42a is formed in a smooth planar shape. On the other hand, the back side of the first light transmitting plate 42 forms a planar joining surface 42 b joined to the phase difference plate 46. Such a first light transmitting plate 42 substantially maintains the polarization state of the light source light in the medium.

  The second light transmissive plate 44 is formed in a light transmissive plate shape by glass, for example, and is disposed on the back side of the phase difference plate 46 in the projection member 40. The back side of the second light transmissive plate 44 forms a second surface 44a as an interface with the space outside the vehicle 1 room. In particular, in the first embodiment, a portion where an image is projected on the second surface 44a is formed in a smooth planar shape. On the other hand, the front side of the second light transmitting plate 44 forms a planar joining surface 44 b joined to the phase difference plate 46. Such a second translucent plate 44 substantially maintains the polarization state of the light source light in the medium.

  The phase difference plate 46 is formed, for example, in a translucent plate shape or film shape with a synthetic resin, and is joined to the first translucent plate 42 and the second translucent plate 44 at both joint surfaces 42b and 44b. The phase difference plate 46 has a fast axis 46a and a slow axis 46b that delays the phase with respect to the fast axis 46a along the tangential direction of the joint surfaces 42b and 44b. That is, the refractive index ηS in the direction along the slow axis 46b is larger than the refractive index ηF in the direction along the fast axis 46a.

  In the projection member 40, the difference between the refractive index η1 of the first light transmitting plate 42 and the refractive index η0 of the space is set to be larger than the difference between the refractive index η1 and the refractive indexes ηF and ηS. Similarly, the difference between the refractive index η1 of the first light transmitting plate 42 and the refractive index η0 of the space is set larger than the difference between the refractive index η1 and the refractive indexes ηF and ηS.

  In the first embodiment, the first surface 42a and the second surface 44a are formed substantially parallel to each other, and the distance DST between them is substantially constant at an arbitrary location. The plate thickness TR of the phase difference plate 46 is substantially constant.

As shown in FIGS. 4 and 5, the optical system 14 is incident on the first surface 42 a of the projection member 40 obliquely along the incident surface PI. Here, the incident surface PI in the present embodiment is a plane including the light beam of the light source incident on the first surface 42a and the normal line NI of the first surface 42a at the location where the light beam enters the first surface 42a. is there. In this embodiment, among the components of the light source light that vibrate the electric field, the component perpendicular to the incident surface PI is defined as the s-polarized component, and the component parallel to the incident surface PI is defined as the p-polarized component. At this time, the light source light is incident on the first surface 42a by the optical system 14 so as to include both the s-polarized component and the p-polarized component.

And the slow axis 46b of the phase difference plate 46 is inclined with respect to the incident surface PI.

In the HUD device 10 and the projection member 40 mounted on the vehicle 1 as in the present embodiment, the light source light from the optical system 14 is inclined by the angle β in the left-right direction D2 of the vehicle 1 with respect to the vertical direction D1 of the vehicle 1. The light enters the first surface 42a of the projection member 40 from the direction. That is, the incident surface PI is inclined by an angle β with respect to the vertical direction D1 of the vehicle 1. The light source light from the optical system 14 is incident on the first surface 42a of the projection member 40 at an incident angle α within the incident surface PI.

  Here, the case where the projection member does not include the retardation plate 46 and is a glass single plate is taken as a comparative example. The simulation of the comparative example will be described below with reference to FIGS.

  A simulation of the HUD device 10 and the projection member 40 according to the first embodiment will be described below with reference to FIGS.

The simulation conditions according to the first embodiment will be described. The incident angle α is 65 °. The light source light incident on the first surface 42a from the optical system 14 is linearly polarized light having a polarization direction DP0 inclined by 45 ° as an angle φ with respect to the incident surface PI. The wavelength λ of the light source light incident on the first surface 42a from the optical system 14 is 550 nm. Note that the inclination angle β of the incident surface PI in this simulation is −5 °. Here, when the angle β is a negative value, the incident surface PI is inclined in the direction opposite to the arrow indicating β in FIG. 5 with respect to the vertical direction D1 (that is, with the optical system 14 in FIG. 5). The position of the eye 4 is changed to the left and right).

In the projection member 40, the first light transmitting plate 42 has a thickness T1 of 5 mm and a refractive index η1 of 1.51633 with respect to the wavelength λ. The second light transmissive plate 44 has a plate thickness T2 of 5 mm and a refractive index η2 with respect to the wavelength λ of 1.51633. The plate thickness TR of the phase difference plate 46 is 0.2 mm. The retardation value R of the phase difference plate 46 is λ / 2. An angle θ of the slow axis 46b of the retardation plate 46 with respect to the incident surface PI is 45 °.

  In the simulation of the comparative example, the arrangement of the projection members with respect to the HUD device is the same as in the simulation according to the first embodiment. In the projection member of the comparative example, the thickness of the glass single plate is T1 + T2 + TR. In the simulation of the comparative example, the internal configuration of the HUD device 10 has the same conditions as the simulation according to the first embodiment.

In the graphs shown in FIGS. 6 and 8, a polarizing plate 60 (see the broken line in FIG. 1) that assumes polarized sunglasses is arranged between each projection member and the occupant's eye 4, and the occupant passes through the polarizing plate 60. The luminance of the light source light incident on the eye 4 is shown in cd / m ² unit. The axis in the circumferential direction indicates the direction of the transmission axis 60a of the polarizing plate 60 as an angle. Specifically, the 0 ° direction in FIG. 6 indicates a direction in which the transmission axis 60a coincides with the vertical direction D1 of the vehicle 1, and the 90 ° direction indicates a direction in which the transmission axis 60a coincides with the horizontal direction D2 of the vehicle 1. Indicates. In general polarized sunglasses, the direction of the transmission axis 60a is 90 °. The radial axis indicates the luminance when the transmission axis 60a is in each direction.

  In the comparative example, as shown in FIG. 6, the luminance of the light source light that is transmitted through the polarizing plate 60 and incident on the occupant's eye 4 fluctuates greatly at an angle close to 90 ° when the transmission axis 60a is rotated. The minimum value Lmin is taken. At 90 ° corresponding to general polarized sunglasses, the brightness can be obtained only about 1/5 of the peak direction. In addition, when the occupant wears general polarized sunglasses, if the transmission shaft 60a rotates by tilting the neck to the side or the like, it is assumed that the minimum luminance value Lmin is straddled, and the visibility deteriorates due to the luminance variation. There is a concern to do.

  On the other hand, in the simulation according to the first embodiment, as shown in FIG. 8, the luminance of the light source light that passes through the polarizing plate 60 and enters the occupant's eye 4 can be obtained even when the transmission axis 60 a of the polarizing plate 60 is rotated. In all directions, it is higher than that of the comparative example and has a minimum value Lmin, but there is little fluctuation. Therefore, when the occupant wears general polarized sunglasses, even if the transmission shaft 60a rotates by shaking his / her neck, it is assumed that there is less fluctuation in the brightness of the virtual image 3 than in the comparative example. Even when the direction of the transmission axis 60a of the polarizing plate 60 is 90 °, the luminance is 1/2 or more of the peak direction.

  In order to obtain further understanding, the polarization directions DP1 and DP2 of the light source light reflected from each surface will be described using the graphs shown in FIGS. 7 and 9, the light source light whose electric field vibrates along the vertical direction D1 of the vehicle 1 is p-polarized light, and the light source light whose electric field vibrates along the horizontal direction D2 of the vehicle 1 is s-polarized light. Please be careful.

  In the comparative example, as shown in FIG. 7, both the polarization direction DP1 of the light source light reflected on the first surface on the front side and the polarization direction DP2 of the light source light reflected on the second surface on the back side are both the first on the front side. It is on the s-polarization side with respect to the polarization direction DP0 of the light source light incident on the surface.

  On the other hand, in the simulation according to the first embodiment, as shown in FIG. 9, the polarization direction DP1 of the light source light reflected on the first surface 42a is the polarization of the light source light incident on the first surface 42a as in the comparative example. It is on the s-polarization side from the direction DP0. However, unlike the comparative example, the polarization direction DP2 of the light source light reflected by the second surface 44a is on the p polarization side with respect to the polarization direction DP0 of the light source light incident on the first surface 42a.

  The inventor further performed additional simulation on the conditions of the phase difference plate 46 for sufficiently obtaining the naked eye luminance and the sunglasses luminance for the HUD device 10 and the projection member 40 according to the first embodiment. That is, the luminance of the light source light incident on the occupant's eye 4 when the retardation value R of the phase difference plate 46 was changed and the direction of the slow axis 46b was changed was examined. This will be described with reference to FIGS. Here, the naked eye luminance in the present embodiment is the luminance of the virtual image 3 visually recognized by an occupant with naked eyes, and the sunglasses luminance is the luminance of the virtual image 3 visually recognized by an occupant wearing the above-described general polarized sunglasses. It is brightness.

The conditions for the additional simulation will be described. The incident angle α is 65 °. The light source light incident on the first surface 42a from the optical system 14 is linearly polarized light having a polarization direction DP0 inclined by 45 ° as an angle φ with respect to the incident surface PI. The wavelength λ of the light source light incident on the first surface 42a from the optical system 14 is 550 nm. Note that the inclination angle β of the incident surface PI in this simulation is 5 °.

  In the projection member 40, the first light transmitting plate 42 has a thickness T1 of 5 mm and a refractive index η1 of 1.51633 with respect to the wavelength λ. The second light transmissive plate 44 has a plate thickness T2 of 5 mm and a refractive index η2 with respect to the wavelength λ of 1.51633. The plate thickness TR of the phase difference plate 46 is 0.2 mm.

  Further, the light emission amount of the light source 12 in the HUD device 10 is different from the simulations corresponding to FIGS.

  Under such conditions, the retardation value R of the retardation plate 46 was changed from 0 to λ, and the angle θ was changed from 0 to 90 ° as the direction of the slow axis 46b.

  In the graphs shown in FIGS. 10 and 11, the retardation value R is taken on the x axis, the angle θ of the slow axis 46b is taken on the y axis, and the luminance (naked eye luminance in FIG. 10 and sunglasses luminance in FIG. 11) is taken on the z axis. Is taking.

As shown in FIG. 10, the naked eye luminance takes two extreme values L1 and L2 at a position where the retardation value R is approximately λ / 2. In the vicinity of the minimum value L1, which is one extreme value, it is estimated that the polarization direction of the light source light transmitted through the phase difference plate 46 is rotated to the p-polarization side as in Patent Document 1, and the reflectance of the second surface 44a. And the naked eye luminance is less than 5,000 cd / m ² . On the other hand, around the maximum value L2, which is the other extreme value, the naked eye luminance exceeds 7,000 cd / m ² .

As shown in FIG. 11, the sunglasses luminance has a maximum value L3 at a position where the retardation value R is approximately λ / 2. In the vicinity of the maximum value L3, the sunglasses luminance exceeds 1,000 cd / m2. In the additional simulation, the angle θ of the slow axis 46b is an angle with respect to the incident surface PI. For example, if the angle θ of the slow axis 46b is 0 °, the slow axis 46b is disposed along the incident surface PI. If the angle θ of the slow axis 46b is 45 °, the slow axis 46b Is aligned with the polarization direction DP0 of the light source light incident on the first surface 42a in this embodiment, and if the angle of the slow axis 46b is 90 °, the slow axis 46b is the incident surface. It will be arranged orthogonal to PI.

Therefore, it is preferable that the slow axis 46b is 40 to 80 ° with respect to the incident surface PI as a condition of the phase difference plate 46 such that the naked eye luminance is higher than that when the retardation value R is 0. Further, the retardation value R is preferably 2/7 · λ ≦ R ≦ 5/7 · λ. In these conditions, it is considered that the sunglasses luminance exceeds 1,000 cd / m 2.

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

In the projection member 40 according to the first embodiment, the first light transmitting plate 42 that maintains the polarization state is obliquely incident on the front side first surface 42a along the incident surface PI, and the s-polarized component and the p-polarized light. The light source light including both components is reflected around the s-polarized component and transmitted through the first light-transmitting plate 42 around the p-polarized component on the first surface 42a on the front side. Here, the phase difference plate 46 is sandwiched between the first light transmission plate 42 and the second light transmission plate 44 in a state where the slow axis 46b is inclined with respect to the incident surface PI. Due to the action of the phase difference plate 46, the polarization direction of the light source light centered on the p-polarized light component transmitted through the first light transmission plate 42 is rotated to the s-polarization side. Furthermore, according to the second light transmitting plate 44 having the second surface 44a on the back side and maintaining the polarization state, the light source light transmitted through the phase difference plate 46 and rotated to the s-polarized side is the second surface 44a. Therefore, the brightness of the virtual image 3 visually recognized by the occupant can be increased. Therefore, the visibility of the virtual image 3 can be enhanced.

Further, the light source light reflected by the second surface 44a on the back side is transmitted again through the phase difference plate 46, and the polarization direction of the light source light is a slow phase inclined with respect to the incident surface PI which is the direction of p-polarized light. By the action of the phase difference plate 46 having the axis 46b, it is rotated again toward the direction of the p-polarized light. According to this, even when the occupant is wearing general polarized sunglasses, the light source light that reflects the front-side first surface 42a and has the s-polarized component as the center, and the back-side second surface 44a. Since both the light source light that reflects the light and the p-polarized light component is incident on general polarized sunglasses, the virtual image 3 can be visually recognized.

In addition, according to the first embodiment, according to the slow axis 46b that forms 40 to 80 degrees with respect to the incident surface PI, the polarization direction of the light source light is reliably rotated to the s-polarization side, so that it is visually recognized by the passenger. The brightness of the virtual image 3 can be increased.

  Further, according to the first embodiment, 2/7 · λ ≦ R ≦ 5/7 · λ is satisfied. According to this, since it is possible to avoid that the light source light transmitted through the first light transmissive plate 42 remains centered on the p-polarized component, the visibility of the virtual image 3 can be improved.

Further, the HUD device 10 according to the first embodiment causes the light source light emitted from the light source to be incident obliquely on the first surface 42a along the incident surface PI by the optical system 14, and the s-polarized component and the p-polarized light. Incident so as to include both components. Such light source light is reflected around the s-polarized component on the first surface 42a on the front side and passes through the first light-transmitting plate 42 around the p-polarized component. Here, the phase difference plate 46 is sandwiched between the first light transmission plate 42 and the second light transmission plate 44 in a state where the slow axis 46b is inclined with respect to the incident surface PI. Due to the action of the phase difference plate 46, the polarization direction of the light source light centered on the p-polarized light component transmitted through the first light transmission plate 42 is rotated to the s-polarization side. Furthermore, according to the second light transmitting plate 44 having the second surface 44a on the back side and maintaining the polarization state, the light source light transmitted through the phase difference plate 46 and rotated to the s-polarized side is the second surface 44a. Therefore, the brightness of the virtual image 3 visually recognized by the occupant can be increased. Therefore, the visibility of the virtual image 3 can be enhanced.

Further, the light source light reflected by the second surface 44a on the back side is transmitted again through the phase difference plate 46, and the polarization direction of the light source light is a slow phase inclined with respect to the incident surface PI which is the direction of p-polarized light. By the action of the phase difference plate 46 having the axis 46b, it is rotated again toward the direction of the p-polarized light. According to this, even when the occupant is wearing general polarized sunglasses, the light source light that reflects the front-side first surface 42a and has the s-polarized component as the center, and the back-side second surface 44a. Since both the light source light that reflects the light and the p-polarized light component is incident on general polarized sunglasses, the virtual image 3 can be visually recognized.

(Second Embodiment)
As shown in FIGS. 12-14, 2nd Embodiment of this invention is a modification of 1st Embodiment.

In the projection member 240 of the second embodiment, the first light transmissive plate 242, the second light transmissive plate 244, and the phase difference plate 246 cooperate to display an image of the projection member 240 as shown in FIGS. An interval changing portion 248 is formed at the projected location. In the interval changing portion 248, the interval DST between the first surface 242a and the second surface 244a increases and increases as it goes from the incident side to the reflecting side. Here, the incident side in the present embodiment is a side on which light source light is incident on a portion of the incident surface PI that is incident on the first surface 242a, and the reflective side is the first surface 242a of the incident surface PI. The light source light is reflected from the first surface 242a with respect to the incident portion. In other words, the side where the light source light is incident is the incident side across the normal line NI of the incident portion, and the side where the light source light is reflected is the reflective side.

  In such an interval changing portion 248, the plate thickness TR of the phase difference plate 246 is formed to be substantially constant. In other words, in the second embodiment, the gap changing portion 248 is formed such that the plate thicknesses T1 and T2 of the first light transmitting plate 242 and the second light transmitting plate 244 increase and change from the incident side toward the reflecting side. .

  In the HUD device 10 that projects an image onto such a projection member 240 to display a virtual image so that the image can be seen by the occupant, in the second embodiment, as shown in FIG. 12, polarized sunglasses 270 are used by the occupant. ing.

  As shown in FIG. 14, the polarization sunglasses 270 includes a frame portion 272 and a pair of polarization filter portions 274. The frame part 272 is a bridge part that connects the pair of rim parts 272b and the pair of rim parts 272b that holds the pair of temple parts 272a that holds the polarized sunglasses 270 by being hooked on the ears of the passenger. 272c and the like. The frame portion 272 is formed substantially symmetrically.

  The pair of polarizing filter units 274 controls incident light incident on the left eye or right eye of the occupant, respectively. Each polarizing filter portion 274 is formed by attaching a polarizing film 274b as a polarizer on the side opposite to the occupant's eye 4 in a base material 274a made of a synthetic resin such as polycarbonate. Such a polarizing filter portion 274 is formed in a meniscus shape having a convex surface on the side opposite to the occupant's eye 4 and a concave surface on the occupant's eye 4 side, for example. The polarizing filter unit 274 does not have to have a refractive power substantially, and corrects the imaging state of an image (including the virtual image 3) that is visually recognized by the occupant when the refractive power is given. There may be.

  The polarizing film 274b is formed, for example, by adding iodine to polyvinyl alcohol. Depending on the orientation direction of the iodine molecules, the polarizing film 274b transmits the incident light according to the polarization direction DPS of the incident light to be incident on the occupant's eye 4, and blocks the incident light. It has a shaft 274d. In particular, in this embodiment, the transmission axis 274c and the blocking axis 274d are substantially orthogonal to each other, and the blocking axis 274d absorbs incident light.

  The direction of the blocking shaft 274d is set according to the retardation value R of the phase difference plate 246 of the projection member 240. For example, particularly in the second embodiment, when R = λ / 2 and the angle θ of the slow axis 46b is 45 ° with respect to the vertical direction D1 of the vehicle 1 as a moving body, the blocking shaft 274d is It is set along. That is, the blocking shaft 274d is set along the vertical center line HC defined based on the boxing method in the frame portion 272 of the polarized sunglasses 270. Here, the boxing method (see JIS B7281: 2003) is a dimension measurement method based on a rectangle circumscribing the polarizing filter portion 274. Note that λ is the wavelength of the light source light used by the HUD device 10.

Also in the second embodiment described above, the projection member 240 has the first light transmitting plate 242 having the first surface 242a on the front side facing the occupant and maintaining the polarization state, and the first side on the back side opposite to the front side. The second light-transmitting plate 244 that has two surfaces 244a and maintains the polarization state, and is sandwiched between the first light-transmitting plate 242 and the second light-transmitting plate 244, and is fastened to the fast axis 46a and the fast axis 46a. And a phase difference plate 246 having a slow axis 46b for delaying the phase. The light source light used by the HUD device 10 is incident on the first surface 242a obliquely along the incident surface PI, and includes both the s-polarized component and the p-polarized component. Further, the slow axis 46b of the phase difference plate 246 is inclined with respect to the incident surface PI. Therefore, it is possible to achieve the operational effects according to the first embodiment.

  Further, according to the second embodiment, the interval changing portion 248 is formed in which the interval DST between the first surface 242a and the second surface 244a increases and increases as it goes from the incident side to the reflecting side. According to this, since the reflection direction of the light source light that reflects the first surface 242a on the front side and the reflection direction of the light source light that reflects the second surface 244a on the back side approach each other, a virtual image formed by reflecting the first surface 242a 3 and the virtual image 3 formed by reflecting the second surface 244a can be suppressed. In the interval changing portion 248 where the interval DST changes in this way, the plate thickness of the phase difference plate 246 is constant. According to this, since the action of the phase difference plate 246 acts uniformly over a wide range of the image, luminance unevenness of the virtual image 3 can be suppressed. As described above, since it is possible to achieve both suppression of the double image and luminance unevenness, the visibility of the virtual image 3 is further enhanced.

  Further, even when wearing polarized sunglasses that is mounted on the vehicle 1 and generally has a blocking axis fixed in the horizontal direction, outside light such as sunlight reflected on the water surface or snow surface in the scenery in front of the vehicle 1 can be obtained. Since the polarization direction is changed by the phase difference plate 246 when passing through the projection member 240, the function as polarized sunglasses cannot be sufficiently exhibited. Here, in the polarized sunglasses 270 of the second embodiment in which the blocking axis 274d is set according to the retardation value R of the retardation film 246, dazzling outside light such as sunlight reflected on the water surface or snow surface is sufficiently blocked. Therefore, the contrast of the virtual image 3 is increased and the visibility can be improved.

  Further, according to the second embodiment, the blocking shaft 274d is set along the vertical direction. According to this, when the retardation value of the phase difference plate 246 is R = 1/2 · λ and the direction of the slow axis 46 b is 45 ° with respect to the vertical direction of the vehicle 1, Since dazzling outside light such as reflected sunlight can be sufficiently blocked, the contrast of the virtual image 3 is increased and visibility can be improved.

(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 regarding the first to second embodiments, the projection member 40 may not be formed integrally with the vehicle 1 as a windshield of the vehicle 1. As an example of this, as shown in FIG. 15, the projection member 40 may be a combiner installed in the vehicle 1 and provided separately from the windshield.

As a second modification related to the first to second embodiments, the angle θ of the slow axis 46b with respect to the incident surface PI is not limited to 40 to 80 °. On the other hand, the angle of the slow axis 46b with respect to the incident surface PI is further preferably set to 50 to 60 °.

  As a third modification regarding the first to second embodiments, the retardation value R of the retardation plate 46 is not limited to the range of 2/7 · λ ≦ R ≦ 5/7 · λ. As an example of this, the retardation value R of the retardation plate 46 is defined as (2/7 + n) · λ ≦ R ≦ (5/7 + n) when the wavelength of the light source is defined as λ and n is defined as an arbitrary integer of 0 or more. ) · Λ may be satisfied. Further, the retardation value R of the retardation plate 46 may not be in the range of (2/7 + n) · λ ≦ R ≦ (5/7 + n) · λ.

  As a fourth modification regarding the first to second embodiments, the light source light may include a plurality of wavelengths as the wavelength λ. For example, with a color filter (not shown) arranged on the liquid crystal panel 26, the wavelength λ of the light source light that forms the image is, for example, λ1 corresponding to red, λ2 corresponding to green, and λ3 corresponding to blue. It may be. In the case of including a plurality of wavelengths, it is preferable that (2/7 + n) · λ ≦ R ≦ (5/7 + n) · λ holds for all wavelengths λ, but at least one wavelength among the wavelengths λ ( 2/7 + n) · λ ≦ R ≦ (5/7 + n) · λ may be satisfied.

  As a fifth modified example related to the first to second embodiments, the optical system 14 of the HUD device 10 is not limited to linearly polarized light and elliptically polarized light, and causes circularly or randomly polarized light source light to be incident on the first surface 42a. May be.

  As a sixth modified example related to the first to second embodiments, the projection member 40 may be entirely curved in accordance with the design of the vehicle 1.

  As a seventh modification, an occupant wearing the polarized sunglasses 270 in the configuration of the second embodiment may visually recognize the image projected on the projection member 40 in the configuration of the first embodiment. In addition, an image projected on the projection member 240 in the configuration of the second embodiment may be visually recognized by a naked-eye occupant or an occupant wearing general polarized sunglasses.

  As a modification 8 related to the second embodiment, the blocking shaft 274d may not be set along the vertical direction as long as it is set according to the retardation value R of the retardation film 246. Here, the setting according to the retardation value R of the phase difference plate 246 means that the blocking axis 274d is aligned with the polarization direction DPS of the external light changed by the phase difference plate 246 when passing through the projection member 240. .

  As a ninth modified example related to the first to second embodiments, the present invention may be applied to various moving bodies (transport equipment) such as a ship other than the vehicle 1 or an airplane.

DESCRIPTION OF SYMBOLS 1 Vehicle (mobile body), 10 HUD apparatus, 12 Light source, 14 Optical system, 40,240 Projection member, 42,242 1st light transmission board, 42a, 242a 1st surface, 44,244 2nd light transmission board, 44a 244a 2nd surface, 46,246 phase difference plate, 46a phase advance axis, 46b
Slow axis, 248 Interval changing part, 270 Polarized sunglasses, 274b Polarized film (polarizer), 274c Transmission axis, 274d Blocking axis, DPS Polarization direction, DST interval, D1
Vertical direction, PI incident surface , R retardation value, TR plate thickness, λ wavelength

Claims (8)

In the head-up display device (10) mounted on the moving body (1) and displaying a virtual image so that the image can be visually recognized by the occupant using the light source light, the projection member projects the image,
A first translucent plate (42, 242) having a first surface (42a, 242a) on the front side facing the passenger and maintaining the polarization state;
A second translucent plate (44, 244) having a second surface (44a, 244a) on the back side opposite to the front side and maintaining the polarization state;
A phase difference plate (46) sandwiched between the first light transmission plate and the second light transmission plate and having a fast axis (46a) and a slow axis (46b) for delaying the phase relative to the fast axis. 246), and
The light source light is obliquely incident on the first surface along an incident surface (PI), and includes both an s-polarized component and a p-polarized component,
The projection member, wherein the slow axis of the retardation plate is inclined with respect to the incident surface . When the side on which the light source light is incident on the first surface (242a) is defined as an incident side and the side to be reflected is defined as a reflective side,
In the interval changing portion (248) formed jointly by the first light transmitting plate (242), the second light transmitting plate (244), and the phase difference plate (246), the first surface and the second surface The distance (DST) from the surface (244a) increases and changes as it goes from the incident side to the reflection side,
2. The projection member according to claim 1, wherein a thickness (TR) of the retardation plate is constant in the interval changing portion. The projection member according to claim 1, wherein the slow axis (46 b) forms 40 to 80 ° with respect to the incident surface . When the retardation value of the retardation plate (46) is defined as R, the wavelength of the light source light is defined as λ, and n is defined as an arbitrary integer of 0 or more,
(2/7 + n) · λ ≦ R ≦ (5/7 + n) · λ
The projection member according to claim 1, wherein: is established. A head-up display device that is mounted on a moving body (1) and displays a virtual image so that the occupant can visually recognize the image by projecting an image onto a projection member (40, 240),
A light source (12) that emits light;
An optical system (14) for making the light source light incident on the projection member;
The projection member has a first surface (42a, 242a) on the front side facing the occupant, a first translucent plate (42, 242) that maintains the polarization state, and a second surface on the back side opposite to the front side. (44a, 244a) and sandwiched between the second light transmitting plate (44, 244) that maintains the polarization state, and the first light transmitting plate and the second light transmitting plate, and a fast axis ( 46a) and a retardation plate (46, 246) having a slow axis (46b) for retarding the phase with respect to the fast axis,
The optical system causes the light source light to enter the first surface obliquely along an incident surface (PI) inclined with respect to the slow axis, and includes both an s-polarized component and a p-polarized component. The head-up display device is characterized by being incident on the head. When the side on which the light source light is incident on the first surface (242a) is defined as an incident side and the side to be reflected is defined as a reflective side,
In the interval changing portion (248) formed jointly by the first light transmitting plate (242), the second light transmitting plate (244), and the phase difference plate (246), the first surface and the second surface The distance (DST) from the surface (244a) increases and changes as it goes from the incident side to the reflection side,
6. The head-up display device according to claim 5, wherein a thickness (TR) of the retardation plate is constant in the interval changing unit. 7. The head-up display device according to claim 5, wherein the slow axis (46 b) forms 40 to 80 ° with respect to the incident surface . 8. When the retardation value of the retardation plate (46) is defined as R, the wavelength of the light source light is defined as λ, and n is defined as an arbitrary integer of 0 or more,
(2/7 + n) · λ ≦ R ≦ (5/7 + n) · λ
The head-up display device according to claim 5, wherein: is established.

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