JP2024072331A - Vehicle display device - Google Patents

Abstract

[Problem] To improve the durability of a wave plate. [Solution] A display device includes a display device, a reflecting member that reflects the display light emitted from the display device in a housing and projects it on a projection target Rwf, a polarization switching unit that switches the polarization direction of the display light emitted from the display device between a polarized sunglasses non-use mode and a polarized sunglasses use mode and outputs the display light to the reflecting member, and a control device that controls the operation of the polarization switching unit. The polarization switching unit (50) includes a light-transmitting, plate-like base plate 51, a wave plate 52 that is provided by overlapping an output surface 52a on a wall surface 51a of the base plate on the display device side, and is capable of changing the polarization direction of the display light emitted from the display device and outputting it, and a drive device 53 that can rotate the wave plate. An infrared light blocking layer 57 that transmits visible light but reflects infrared light is provided on the wall surface 51b of the base plate on the reflecting member side. [Selected Figure] Figure 2

Description

The present invention relates to a display device for a vehicle.

Conventionally, a vehicle is equipped with a vehicle display device that displays information to be provided to a passenger in the vehicle cabin as a virtual image. This vehicle display device is a so-called head-up display device, and includes a display device that emits display information to be projected onto a projection target as display light, and a reflecting member that reflects the display light emitted from the display device and projects the display light onto a projection target such as a windshield. This vehicle display device allows the passenger to view display information corresponding to the display light projected onto the projection target as a virtual image. In this type of vehicle display device, reflected light mainly composed of S-polarized light is reflected from the projection target toward the passenger. However, in general, the S-polarized light is cut by polarized sunglasses. For this reason, when the passenger is wearing polarized sunglasses, the brightness of the virtual image is reduced compared to when the passenger is not wearing the polarized sunglasses, and the visibility of the virtual image is reduced. For example, the following Patent Document 1 discloses a technology in which the polarization direction of the display device's emitted light (display light) is switched between when polarized sunglasses are used and when they are not used, and when polarized sunglasses are used, the reflected light of the polarized component that can pass through the polarized sunglasses is reflected. The vehicle display device in Patent Document 1 uses an electric motor to drive and rotate the wave plate onto which the emitted light is incident, in order to switch the polarization direction of the light emitted from the display depending on whether or not polarized sunglasses are being used.

JP 2013-57897 A

However, in conventional vehicle display devices, a wave plate is placed between the display and the reflective member, and external light is reflected by the reflective member and directed toward the wave plate. Therefore, in this vehicle display device, when external light is incident on the wave plate, the wave plate may heat up due to the influence of infrared light, which may reduce its durability.

The present invention aims to provide a vehicle display device that can improve the durability of the wave plate.

The present invention comprises a housing, a display device that emits display information as a virtual image to be viewed by an occupant in the vehicle cabin as display light within the housing, a reflecting member that reflects the display light emitted from the display device within the housing and projects the display light from an opening in the housing to a projection target within the vehicle cabin, a polarization switching unit that is disposed between the display device and the reflecting member and that switches the polarization direction of the display light emitted from the display device between a polarized sunglasses non-use mode in which the occupant is not using polarized sunglasses and a polarized sunglasses use mode in which the occupant is using polarized sunglasses, and emits the display light to the reflecting member, and a control device that controls the operation of the display device and the polarization switching unit, the polarization switching unit comprising a light-transmitting, plate-shaped base plate and a polarizing element attached to the base plate. The device is equipped with a wave plate that has an exit surface superimposed on the wall surface on the display side of the display device and is capable of changing the polarization direction of the display light emitted from the display device and emitting it from the exit surface, and a drive unit that uses an electric motor controlled by the control device as a drive source and can rotate the wave plate between a polarized sunglasses not used position in the polarized sunglasses not used mode and a polarized sunglasses used position in the polarized sunglasses used mode, and emits transmitted light with a main component of S-polarized component from the wave plate in the polarized sunglasses not used position, while emitting transmitted light with a main component of P-polarized component from the wave plate in the polarized sunglasses used position, and an infrared light blocking layer that transmits visible light but reflects infrared light is provided on the wall surface of the base plate on the reflecting member side.

In the vehicle display device according to the present invention, the infrared light blocking layer allows visible light (i.e., the display light of the display device passing through the base plate and the wave plate) to pass through, so that the display information related to the display light of the display device can be visually recognized by the occupant as a virtual image. In addition, in this vehicle display device, even if external light that has entered the housing from the opening is directed toward the base plate and the wave plate, the infrared light in the external light is reflected by the infrared light blocking layer and does not reach the wave plate. Therefore, in this vehicle display device, heat generation of the wave plate caused by infrared light is suppressed, so the durability of the wave plate can be improved.

FIG. 1 is a schematic diagram showing a vehicle display device according to an embodiment. FIG. 2 is a schematic diagram illustrating an optical path of the vehicle display device according to the embodiment. FIG. 3 is a perspective view showing a polarization switching unit. FIG. 4 is a perspective view of the polarization switching unit as seen from a different angle. FIG. 5 is an exploded perspective view showing the polarization switching unit.

Below, an embodiment of a vehicle display device according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to this embodiment.

[Embodiment]
An embodiment of a display device for a vehicle according to the present invention will be described with reference to FIGS.

The reference numeral 1 in Fig. 1 and Fig. 2 indicates a vehicle display device according to an embodiment. This vehicle display device 1 is a so-called head-up display device that displays information to passengers in the vehicle (such as an automobile) as a virtual image.

This vehicle display device 1 projects display light related to display information onto a projection target such as a windshield in the vehicle cabin, and reflects the display light toward the occupant from the projection target, thereby allowing the occupant to view a virtual image of the display information. Here, since the P-polarized component is less likely to be reflected from the projection target than the S-polarized component, the main component of the reflected light toward the occupant is S-polarized light. On the other hand, polarized sunglasses that the occupant may use are primarily intended to cut S-polarized light. For this reason, when polarized sunglasses are used, the brightness of the virtual image is lower than when the polarized sunglasses are not used. Therefore, this vehicle display device 1 is configured as follows, and by reducing the difference in brightness of the virtual image between when the occupant is not using polarized sunglasses and when the occupant is using polarized sunglasses, the visibility of the virtual image when polarized sunglasses are used is improved.

The vehicle display device 1 includes a display device 10 that emits display information as display light within a housing 71 described below, which is to be viewed as a virtual image by occupants in the vehicle cabin (FIGS. 1 and 2). The display device 10 includes a backlight unit 20 and a light-transmitting, plate-shaped display unit 30, and transmits light irradiated from the backlight unit 20 to the display unit 30, causing it to be emitted from the display unit 30 as display light for the display information (FIGS. 1 and 2).

Furthermore, the vehicle display device 1 includes a reflecting member 40 that reflects the display light emitted from the display 10 inside the housing 71 and projects the display light from the opening 71a of the housing 71 onto the projection area Rwf inside the vehicle cabin (Figs. 1 and 2). The reflecting member 40 is, for example, a magnifying mirror that magnifies and reflects the display light emitted from the display 10. For example, an aspheric (free-form) mirror is used as the reflecting member 40. The display light projected onto the projection area Rwf is reflected from the projection area Rwf to the eye point EP or eye box EB, and is visually recognized as a virtual image by the occupant (Fig. 1). The eye point EP indicates the position of the eyes of the occupant inside the vehicle cabin. The eye box EB indicates the range of the eye point EP at which the virtual image can be visually recognized.

The vehicle display device 1 further includes a polarization switching unit 50 that is disposed between the display device 10 and the reflecting member 40 and switches the polarization direction of the display light emitted from the display device 10 between a polarized sunglasses non-use mode in which the occupant is not using polarized sunglasses and a polarized sunglasses use mode in which the occupant is using polarized sunglasses, and emits the display light to the reflecting member 40 (FIGS. 1 to 5). The reflecting member 40 receives the light emitted from the polarization switching unit 50 and reflects the emitted light toward the projection target Rwf.

This vehicle display device 1 includes a control device 60 that controls the operation of the display device 10 and the polarization switching unit 50 (Figure 1).

The vehicle display device 1 further includes a housing 71 that houses at least the display 10, the reflecting member 40, and the polarization switching unit 50, and a transparent cover 72 that covers the opening 71a of the housing 71 (FIGS. 1 and 2). In the vehicle display device 1, the display light reflected by the reflecting member 40 is emitted from the cover 72 to the outside of the housing 71, and projected onto the projection target Rwf that exists beyond. The vehicle display device 1 shown here is housed in the instrument panel Pi in the vehicle cabin with the cover 72 exposed, and projects the display light reflected by the reflecting member 40 onto the projection target Rwf (FIG. 1). The vehicle display device 1 then reflects the display light from the projection target Rwf toward the eye point EP or the eye box EB.

Here, the projection portion Rwf refers to the windshield (here, the front windshield Wf) itself or a part thereof. The projection portion Rwf may be formed as a half mirror that receives the display light from the reflecting member 40 on the reflecting surface, reflects it to the eye point EP or the eye box EB, and emits light from outside the vehicle toward the occupant. For example, the projection portion Rwf as a half mirror is formed as a semi-transparent film that conforms to the curved shape of the windshield (front windshield Wf) and is attached to the wall surface of the windshield on the inside of the vehicle compartment with an adhesive. The projection portion Rwf as a half mirror may be formed as a semi-transparent film that conforms to the curved shape of the windshield (front windshield Wf) and is sealed together with an intermediate film in the windshield of the laminated glass. The projection portion Rwf as a half mirror may be a semi-transparent coating that is coated by painting or the like on the wall surface of the windshield (front windshield Wf) on the inside of the vehicle compartment. The projected portion Rwf may be a combiner that covers the front windshield Wf from the inside of the vehicle compartment.

The backlight unit 20 includes a light source 21, a control board 22 for the light source 21, and a heat sink 23 for dissipating heat generated by the light source 21 (Fig. 2). The light source 21 is a light-emitting element. In this example, a light-emitting diode element is used as the light-emitting element. The backlight unit 20 includes a plurality of light sources 21 arranged in the vertical direction. The control board 22 electrically connects the light source 21 to a power source via a wiring pattern. On the board surface 22a of the control board 22 shown here, a plurality of light sources 21 are arranged at equal intervals in both the vertical direction and the direction perpendicular to the vertical direction (Fig. 2).

The backlight unit 20 further includes a focusing lens 24 that is disposed opposite the board surface 22a of the control board 22 and focuses light from the light source 21 (hereinafter referred to as "light source light") that is interposed between the control board 22 and the board surface 22a, and a field lens 25 that diffuses and distributes the light source light focused by the focusing lens 24 (Figure 2).

The condenser lens 24 is a lens member made of glass or transparent resin that condenses the light source light from the light source 21. The condenser lens 24 shown here is, for example, a condenser lens in which lens elements 24a for each light source 21 are arranged facing the light source 21. The lens element 24a has an entrance surface through which the light source light from the light source 21 is incident, and an exit surface through which the light source light incident from the entrance surface is emitted, and is formed as a plano-convex lens with the entrance surface being a flat surface and the exit surface being a convex curved surface.

The field lens 25 is a lens member made of glass or transparent resin that aligns the direction of travel of the light source light emitted from the condenser lens 24, and is interposed between the condenser lens 24 and the display unit 30. This field lens 25 has an entrance surface onto which the light source light of each light source 21 is incident via the condenser lens 24, and an exit surface from which the light source light incident from the entrance surface is emitted. The field lens 25 shown here is, for example, a Fresnel lens.

In the backlight unit 20, the emission surface of the field lens 25 becomes the irradiation surface 20a (Figure 2), and the traveling direction of the light source light from each light source 21 via the condenser lens 24 is aligned by the field lens 25, and the light source light is diffused and distributed from the irradiation surface 20a. This backlight unit 20 irradiates the light source light emitted from the irradiation surface 20a as irradiation light to the display unit 30.

The display unit 30 allows the light irradiated from the irradiated surface 20a of the backlight unit 20 to enter the irradiated surface 30a on the back side, and emits the display light of the display information from the emission surface 30b on the front side toward the polarization switching unit 50 (Figure 2). This display unit 30 transmits the light irradiated from the irradiated surface 20a that has entered the irradiated surface 30a, and emits it from the emission surface 30b as display light. The display unit 30 shown here uses a light-transmitting TFT liquid crystal (Thin Film Transistor Liquid Crystal Display). This display unit 30 is controlled by the control device 60 to display the display information. For example, the display information may be image information such as letters, numbers, and figures.

The polarization switching unit 50 includes a light-transmitting, plate-like base plate 51 and a wave plate 52 that is provided by overlapping an exit surface 52a on the wall surface 51a on the display device 10 side of the base plate 51, and that can change the polarization direction of the display light emitted from the display device 10 and emit it from the exit surface 52a (FIG. 2). Furthermore, the polarization switching unit 50 includes a drive device 53 that can rotate the wave plate 52 between a polarized sunglasses non-use position in a polarized sunglasses non-use mode and a polarized sunglasses use position in a polarized sunglasses use mode (FIG. 3). In the polarization switching unit 50, the base plate 51 and the wave plate 52 are integrated without relative displacement, and the drive device 53 rotates the wave plate 52 together with the base plate 51. For example, the base plate 51 and the wave plate 52 may be integrated by bonding the wall surface 51a and the exit surface 52a with a light-transmitting adhesive. In addition, the base plate 51 and the wave plate 52 may be integrated with each other by forming the wave plate 52 using imprint technology on the wall surface 51a of the glass base plate 51 facing the display 10.

This polarization switching unit 50 emits transmitted light whose main component is S-polarized light from the wave plate 52 in the position where the polarized sunglasses are not used, while emitting transmitted light whose main component is P-polarized light from the wave plate 52 in the position where the polarized sunglasses are used. The base plate 51 is molded as a transparent flat plate member having optical transparency so that the projected light emitted from the emission surface 52a of the wave plate 52 reaches the reflecting member 40. Therefore, in this polarization switching unit 50, the transmitted light emitted from the emission surface 52a of the wave plate 52 enters the base plate 51 from the wall surface 51a on the display 10 side, passes through the base plate 51, and is emitted toward the reflecting member 40 from the wall surface 51b on the reflecting member 40 side of the base plate 51 (Figure 2). In other words, when the rotational position of the wavelength plate 52 is the position where polarized sunglasses are not used, the polarization switching unit 50 projects the projection light whose main component is the S-polarized component from the exit surface 52a of the wavelength plate 52 via the base plate 51 onto the reflecting member 40, while when the rotational position of the wavelength plate 52 is the position where polarized sunglasses are used, the polarization switching unit 50 projects the projection light whose main component is the P-polarized component from the exit surface 52a of the wavelength plate 52 via the base plate 51 onto the reflecting member 40.

The wavelength plate 52 transmits the display light from the display device 10 that is incident on the incident surface 52b so that the main component of the projection light (light emitted from the polarization switching unit 50) to be projected onto the reflecting member 40 is an S-polarized component when the rotation position is the polarized sunglasses not used position (Figure 2). And, this wavelength plate 52 transmits the display light from the display device 10 that is incident on the incident surface 52b so that the main component of the projection light (light emitted from the polarization switching unit 50) to be projected onto the reflecting member 40 is a P-polarized component when the rotation position is the polarized sunglasses used position.

The wave plate 52 is well known in this technical field, and a 1/2 wave plate is used here.

For example, when the display light from the display device 10 is S-polarized, the rotational position of the wave plate 52 where the fast axis coincides with the polarization direction of the display light from the display device 10 is the position where polarized sunglasses are not used. When the rotational position of the wave plate 52 is the position where polarized sunglasses are not used, the wave plate 52 transmits the display light from the display device 10 in its polarization direction. Therefore, when the rotational position of the wave plate 52 is the position where polarized sunglasses are not used, projection light mainly composed of S-polarized components is output from the polarization switching unit 50 to the reflective member 40.

By rotating this wave plate 52 45 degrees from its polarized sunglasses non-use position, the fast axis is shifted by 45 degrees relative to the polarization direction of the display light from the display unit 10, so the display light from the display unit 10 that is incident on the entrance surface 52b is rotated by twice the angle (90 degrees) and emitted from the exit surface 52a as P-polarized transmitted light. Therefore, when the wave plate 52 is rotated 45 degrees from the polarized sunglasses non-use position, projection light mainly composed of P-polarized components is emitted from the polarization switching unit 50 to the reflecting member 40. Therefore, the rotation position of this wave plate 52 rotated 45 degrees from the polarized sunglasses non-use position is the polarized sunglasses use position.

In addition, when the main component of the display light from the display device 10 is not the S-polarized component, the wavelength plate 52 may be arranged as follows in the polarized sunglasses not used position. This wavelength plate 52 shifts the fast axis by a predetermined angle θ with respect to the polarization direction of the display light from the display device 10, rotates the polarization direction of the display light from the display device 10 by twice that angle (2θ), and emits S-polarized transmitted light from the emission surface 52a. The rotation position of the wavelength plate 52 is the polarized sunglasses not used position. Therefore, when the rotation position of the wavelength plate 52 is the polarized sunglasses not used position, projection light mainly composed of S-polarized components is emitted from the polarization switching unit 50 to the reflective member 40.

By rotating this wave plate 52 45 degrees from the polarized sunglasses non-use position, the fast axis is shifted by θ+45 degrees with respect to the polarization direction of the display light from the display unit 10, so the display light from the display unit 10 that is incident on the entrance surface 52b is rotated by twice the angle (2θ+90 degrees) and emitted from the exit surface 52a as P-polarized transmitted light. Therefore, when the wave plate 52 is rotated 45 degrees from the polarized sunglasses non-use position, projection light mainly composed of P-polarized components is emitted from the polarization switching unit 50 to the reflection member 40. Therefore, the rotation position of this wave plate 52 rotated 45 degrees from the polarized sunglasses non-use position is the polarized sunglasses use position.

In other words, regardless of which side of the wave plate 52 is set as the polarized sunglasses non-use position, the wave plate 52 outputs projection light whose main component is S-polarized component from the polarization switching unit 50 toward the reflecting member 40 in the polarized sunglasses non-use position. Therefore, the vehicle display device 1 can allow occupants who are not wearing polarized sunglasses to see a virtual image. Then, by rotating the wave plate 52 45 degrees from the polarized sunglasses non-use position to the polarized sunglasses use position, the wave plate 52 outputs projection light whose main component is P-polarized component from the polarization switching unit 50 toward the reflecting member 40. Therefore, the vehicle display device 1 can allow occupants who are wearing polarized sunglasses to see a virtual image.

The driving device 53 uses an electric motor 54 (FIGS. 3 to 5) controlled by the control device 60 as a driving source, and rotates the wave plate 52 integrated with the base plate 51 around a rotation axis perpendicular to its plane (the incident surface 52b on which the display light emitted from the display device 10 is incident, and the exit surface 52a through which the incident light is transmitted and exits). The driving device 53 includes a power transmission mechanism 55 (FIG. 5) that transmits the output torque of the electric motor 54 to the base plate 51 and the wave plate 52, and a holding mechanism 56 (FIGS. 3 to 5) that holds the peripheral portions of the base plate 51 and the wave plate 52 so that they can rotate freely.

In the driving device 53 shown here, a stepping motor is used as the electric motor 54, and its output torque is transmitted to the base plate 51 and the wave plate 52 via a group of gears serving as a power transmission mechanism 55. The power transmission mechanism 55 includes a spur gear-shaped pinion gear 55A arranged concentrically on the output shaft of the electric motor 54, and a rack 55B arranged on the periphery of the base plate 51 and the wave plate 52 and meshed with the pinion gear 55A (Figure 5).

The holding mechanism 56 includes a first annular guide member 56A and a second annular guide member 56B that surround the peripheral portions of the base plate 51 and the wave plate 52 in the circumferential direction, and a first holding member 56C and a second holding member 56D that rotatably hold the base plate 51 and the wave plate 52 via the first guide member 56A and the second guide member 56B (FIG. 5).

The first guide member 56A and the second guide member 56B are annular members that sandwich and hold the peripheral portions of the base plate 51 and the wave plate 52 when assembled together, exposing the flat surfaces of both the wall surface 51b on the reflecting member 40 side of the base plate 51 and the incident surface 52b of the wave plate 52. At least one of the first guide member 56A and the second guide member 56B has a cylindrical guide protrusion 56a arranged on an axis parallel to the rotation axis of the base plate 51 and the wave plate 52 (Figures 3 to 5). In the holding mechanism 56, a pair of guide protrusions 56a protruding in opposite directions from each other on the parallel axis are provided at intervals in the rotation direction of the base plate 51 and the wave plate 52 (here, four sets). For example, the pair of guide protrusions 56a are cylindrical protrusions that protrude in opposite directions from the annular main body of either the first guide member 56A or the second guide member 56B, and multiple sets are provided with a gap in the circumferential direction on each annular main body. Also, for example, the pair of guide protrusions 56a are a cylindrical protrusion that protrudes from the annular main body of the first guide member 56A and a cylindrical protrusion that protrudes in the opposite direction from the annular main body of the second guide member 56B, and multiple sets are provided with a gap in the circumferential direction on each annular main body. Here, all of the guide protrusions 56a are provided on the first guide member 56A.

Here, the rack 55B is provided on the peripheral portion of either the first guide member 56A or the second guide member 56B. The rack 55B may be formed integrally with the peripheral portion of the main body of either the first guide member 56A or the second guide member 56B, or may be molded as a separate part and fixed to the peripheral portion. Here, the rack 55B is formed integrally with the peripheral portion of the annular main body of the first guide member 56A as part of the first guide member 56A (Figure 5).

The first holding member 56C and the second holding member 56D, when assembled together, rotatably hold the base plate 51 and the wave plate 52 via the first guide member 56A and the second guide member 56B. The first holding member 56C and the second holding member 56D also rotatably hold the first guide member 56A and the second guide member 56B while leaving both the flat surfaces of the wall surface 51b on the reflecting member 40 side of the base plate 51 and the incident surface 52b of the wave plate 52 exposed.

The first holding member 56C is molded as a housing member that houses and rotatably holds the base plate 51, the wave plate 52, the first guide member 56A, and the second guide member 56B. The first holding member 56C shown here also houses and operably holds the power transmission mechanism 55. The second holding member 56D is like a cover member that covers the opening of the first holding member 56C while leaving the incident surface 52b of the wave plate 52 exposed, and rotatably holds the base plate 51, the wave plate 52, the first guide member 56A, and the second guide member 56B. The electric motor 54 is fixed to this second holding member 56D.

The first holding member 56C has a through-hole or groove-shaped guide rail 56b for each pair of guide protrusions 56a that accommodates and guides one of the pair of guide protrusions 56a (FIGS. 4 and 5). Similarly, the second holding member 56D has a through-hole or groove-shaped guide rail 56b for each pair of guide protrusions 56a that accommodates and guides the other of the pair of guide protrusions 56a (FIGS. 3 and 5). The guide rail 56b shown here is formed in a through-hole shape. The pair of guide rails 56b facing each other in the axial direction of the rotation axis of the base plate 51 and the wave plate 52 guide the pair of guide protrusions 56a along the rotation trajectory when the base plate 51 and the wave plate 52 are rotated between the polarized sunglasses non-use position and the polarized sunglasses use position.

The pair of guide protrusions 56a and the pair of guide rails 56b shown here are formed so that, for each combination, the base plate 51 and the wave plate 52 can be rotated at least between a position where polarized sunglasses are not used and a position where polarized sunglasses are used (i.e., at least 45 degrees) from one end of the guide rails 56b to the other end.

In this polarization switching unit 50, the position where the polarized sunglasses are not used is set as the origin of the rotational positions of the base plate 51 and the wave plate 52. For example, here, the origin is the rotational position of the base plate 51 and the wave plate 52 when the guide protrusion 56a is positioned at one end of the guide rail 56b.

The control device 60 drives and controls the electric motor 54 of the drive device 53 and controls the rotational positions of the base plate 51 and the wavelength plate 52 depending on whether the requested viewing mode is a mode without polarized sunglasses or a mode with polarized sunglasses. For example, the control device 60 determines that there has been a command to switch the requested viewing mode to a mode without polarized sunglasses or a mode with polarized sunglasses based on a requested viewing mode switching command signal accompanying a switching operation of a requested viewing mode switching switch by the occupant, a pressing operation or a touch operation of a requested viewing mode setting button, etc., and determines whether the requested viewing mode is a mode without polarized sunglasses or a mode with polarized sunglasses.

When there is a command to switch the requested viewing mode to a mode in which polarized sunglasses are not used or a mode in which polarized sunglasses are used, the control device 60 supplies an excitation current to the electric motor 54 to rotate the base plate 51 and the wave plate 52 to the rotation position of the requested viewing mode. When the requested viewing mode is a mode in which polarized sunglasses are not used, the control device 60 drives and controls the electric motor 54 of the drive device 53 to rotate the base plate 51 and the wave plate 52 to the position in which polarized sunglasses are not used. When the requested viewing mode is a mode in which polarized sunglasses are used, the control device 60 drives and controls the electric motor 54 of the drive device 53 to rotate the base plate 51 and the wave plate 52 to the position in which polarized sunglasses are used.

In this manner, in the vehicle display device 1, the display light of the display 10 is projected onto the reflecting member 40 through the base plate 51 and the wave plate 52 at a rotational position corresponding to the requested viewing mode, and the display light reflected by the reflecting member 40 is projected onto the projection portion Rwf, allowing the occupant to view it as a virtual image. At that time, the display light reflected by the reflecting member 40 exits the housing 71 from the opening 71a and is projected onto the projection portion Rwf in the vehicle cabin. For this reason, in the vehicle display device 1, there is a possibility that external light enters the housing 71 from the opening 71a, and the external light reflected by the reflecting member 40 enters the wave plate 52 through the base plate 51. In addition, in the vehicle display device 1, depending on the shape of the opening 71a and the arrangement of the base plate 51 and the wave plate 52, there is a possibility that the external light that enters the housing 71 from the opening 71a may directly head toward the base plate 51 and the wave plate 52.

Here, the external light includes visible light, infrared light, and the like. Therefore, in this vehicle display device 1, when the external light that has entered the housing 71 is directed toward the base plate 51, the wave plate 52 may generate heat due to the influence of the infrared light, which may reduce its durability.

Therefore, in this vehicle display device 1, an infrared light blocking layer 57 that transmits visible light but reflects infrared light is provided on the wall surface 51b of the base plate 51 facing the reflective member 40 (Figures 2, 4, and 5). This infrared light blocking layer 57 is, for example, a hot mirror provided on the wall surface 51b of the base plate 51 facing the reflective member 40. Therefore, a glass base plate 51 is used here, and the wall surface 51b of the base plate 51 facing the reflective member 40 is subjected to hot mirror processing to form a hot mirror as the infrared light blocking layer 57 on the wall surface 51b.

In the vehicle display device 1 of this embodiment, the infrared light blocking layer 57 can transmit visible light (i.e., the display light of the display device 10 via the base plate 51 and the wave plate 52), so that, as described above, the display information related to the display light of the display device 10 can be visually recognized by the occupant as a virtual image. In addition, in this vehicle display device 1, even if the external light that has entered the housing 71 from the opening 71a heads toward the base plate 51 and the wave plate 52, the infrared light in the external light is reflected by the infrared light blocking layer 57 and does not reach the wave plate 52. Therefore, in this vehicle display device 1, the heat generation of the wave plate 52 caused by the infrared light is suppressed, so that the durability of the wave plate 52 can be improved. Furthermore, in this vehicle display device 1, the infrared light does not reach the display unit 30, and the heat generation of the display unit 30 caused by the infrared light is suppressed, so that the durability of the display unit 30 can also be improved.

In this vehicle display device 1, in order to obtain the same effect as that of the infrared light blocking layer 57, it is also possible to provide a cold mirror as a visible light blocking layer that reflects visible light while transmitting infrared light on the reflective surface of the reflective member 40 by cold mirror treatment. However, since it is difficult to apply cold mirror treatment to a resin material, the reflective member 40 made of resin cannot be used in this vehicle display device 1, and a reflective member 40 made of glass, for example, must be used, which may lead to an increase in weight. In addition, in this vehicle display device 1, in order to increase the magnification rate of the virtual image, the area of the reflective surface of the reflective member 40 is made larger than the area of the wall surface 51b on the reflective member 40 side of the base plate 51. Therefore, for example, when the cold mirror treatment is applied to the glass reflective member 40, the area required for the treatment is larger than that of the hot mirror treatment applied to the base plate 51, which may lead to an increase in cost. Therefore, in this embodiment of the vehicle display device 1, by providing a hot mirror as an infrared light blocking layer 57 on the base plate 51, it is possible to reduce the weight by using a resin reflective member 40 and prevent the cost from rising.

REFERENCE SIGNS LIST 1 Vehicle display device 10 Display 40 Reflecting member 50 Polarization switching unit 51 Base plate 51a Wall surface 51b Wall surface 52 Wave plate 52a Exit surface 52b Incident surface 53 Driving device 54 Electric motor 57 Infrared light blocking layer 60 Control device 71 Housing 71a Opening EB Eye box EP Eye point Rwf Projected portion

Claims (2)

A housing and
a display unit that emits display information as display light within the housing so that the display information is visually recognized as a virtual image by an occupant in the vehicle cabin;
a reflecting member that reflects the display light emitted from the display unit inside the housing and projects the display light from an opening in the housing onto a projection target portion in a vehicle interior;
a polarization switching unit that is disposed between the display and the reflecting member, and switches the polarization direction of the display light emitted from the display between a polarized sunglasses non-use mode in which the occupant is not using polarized sunglasses and a polarized sunglasses use mode in which the occupant is using polarized sunglasses, and emits the display light to the reflecting member;
A control device for controlling the operation of the display device and the polarization switching unit;
Equipped with
The polarization switching unit includes a light-transmitting, plate-shaped base plate, an emission surface of which is superimposed on the wall surface of the base plate facing the display device, a wave plate capable of changing the polarization direction of the display light emitted from the display device and emitting the light from the emission surface, and a drive device having an electric motor controlled by the control device as a drive source, capable of rotating the wave plate between a polarized sunglasses not being used position in the polarized sunglasses not being used mode and a polarized sunglasses used position in the polarized sunglasses used mode, and emits transmitted light whose main component is an S-polarized component from the wave plate in the polarized sunglasses not being used position, and emits transmitted light whose main component is a P-polarized component from the wave plate in the polarized sunglasses used position,
The vehicle display device according to claim 1, wherein an infrared light blocking layer that transmits visible light and reflects infrared light is provided on a wall surface of the base plate facing the reflective member. The vehicle display device according to claim 1, characterized in that the infrared light blocking layer is a hot mirror provided on the wall surface of the base plate on the side of the reflecting member.

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