Vehicular display device

Abstract

A vehicular display device (1) according to the present invention comprises: a housing (71); a display unit (10) that emits, as display light in the housing (71), display information that can be visually recognized as a virtual image by an occupant in the vehicle cabin; a planar mirror (20) that reflects, in the housing (71), the display light emitted from a display (11) of the display unit (10); a first concave mirror (30) that reflects, in the housing (71), the display light reflected by the planar mirror (20); a second concave mirror (40) that reflects, in the housing (71), the display light reflected by the first concave mirror (30), and that causes the display light to be projected from an opening (71a) in the housing (71) to a projection section (Rwf) in the vehicle cabin. A planar mirror that transmits infrared light and a P-polarized light component of visible light and that reflects an S-polarized light component of visible light is used as the planar mirror (20).

Description

Vehicle display device

[0001] The present invention relates to a display device for a vehicle.

[0002] Conventionally, vehicles are equipped with a vehicle display device that displays information to be provided to occupants in the vehicle cabin as a virtual image. This vehicle display device is a so-called head-up display device and includes a display unit that emits display information to be projected onto a projection target as display light, a reflecting member that reflects the display light emitted from the display unit and projects the display light onto the projection target, and a housing that accommodates these. This vehicle display device projects the display light reflected by the reflecting member onto the projection target outside the housing, allowing the occupants to view the display information corresponding to the projected display light as a virtual image. This type of vehicle display device is disclosed, for example, in Patent Document 1 listed below.

[0003] JP 2016-30461 A

[0004] However, in a vehicle display device, while display light is emitted outside the housing, external light enters the housing. Therefore, in this vehicle display device, when the external light is transmitted to the display via the reflective member, the display may be affected by infrared light, generating heat and reducing its durability.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a vehicle display device that can improve the durability of the display.

[0006] The present invention comprises a housing, a display unit that emits display information into the housing as display light to be viewed as a virtual image by occupants in the vehicle cabin, a plane mirror that reflects the display light emitted from a display of the display unit inside the housing, a first concave mirror that reflects the display light reflected by the plane mirror inside the housing, and a second concave mirror that reflects the display light reflected by the first concave mirror inside the housing and projects the display light from an opening in the housing onto a projection target inside the vehicle cabin, and is characterized in that the plane mirror transmits infrared light and P-polarized components of visible light, while reflecting S-polarized components of the visible light.

[0007] In the vehicle display device according to the present invention, when external light enters the housing and propagates to the plane mirror, the plane mirror transmits infrared light and the P-polarized component of visible light, thereby suppressing heat generation in the display of the display unit. Therefore, the vehicle display device according to the present invention can improve the durability of the display unit. In addition, in the vehicle display device according to the present invention, when display light is emitted from the display unit toward the plane mirror, the plane mirror transmits the P-polarized component of the display light (visible light), while the plane mirror reflects the S-polarized component of the display light (visible light) toward the first concave mirror. Therefore, in the vehicle display device according to the present invention, the S-polarized component is reflected by the first concave mirror and then the second concave mirror before propagating to the projection target. Here, since the P-polarized component of the display light (visible light) is less likely to be reflected at the projection target than the S-polarized component, the S-polarized component constitutes the main component of the reflected light toward the occupant. Therefore, the vehicle display device according to the present invention can improve the durability of the display unit without adversely affecting the virtual image display.

[0008] 1 is a schematic diagram illustrating a vehicle display device according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram illustrating an example of the configuration of a plane mirror.

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a vehicle display device according to the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention is not limited to the embodiment.

[0010] [Embodiment] One embodiment of a vehicle display device according to the present invention will be described with reference to FIGS. 1 and 2. FIG.

[0011] 1 indicates a vehicle display device according to this embodiment. The vehicle display device 1 is a so-called head-up display device that displays a virtual image of information to be provided to an occupant in a vehicle (such as an automobile). The vehicle display device 1 projects display light relating to the display information onto a projection surface Rwf, such as a windshield, in the vehicle interior, and reflects the display light from the projection surface Rwf toward the occupant, thereby allowing the occupant to view a virtual image of the display information ( FIG. 1 ).

[0012] The vehicle display device 1 includes a display unit 10 that emits display information as display light into a housing 71 (see FIG. 1 ), which is to be viewed as a virtual image by a vehicle occupant. The display unit 10 includes a backlight (not shown) and a light-transmitting, plate-like display 11. Light irradiated from the backlight onto the display 11 is transmitted through the display 11, and is emitted from the display 11 as display light for display information (see FIG. 1 ). For example, a light-transmitting, TFT liquid crystal (thin film transistor liquid crystal) display or the like is used as the display 11.

[0013] Furthermore, the vehicle display device 1 includes a plurality of reflecting members that reflect the display light emitted from the display 11 of the display unit 10 inside the housing 71 and project the display light onto a projection area Rwf inside the vehicle cabin through the opening 71a of the housing 71. The vehicle display device 1 includes a plane mirror 20, a first concave mirror 30, and a second concave mirror 40 as the reflecting members (FIG. 1).

[0014] The plane mirror 20 reflects the display light emitted from the display 11 of the display unit 10 inside the housing 71. The first concave mirror 30 reflects the display light reflected by the plane mirror 20 inside the housing 71. The second concave mirror 40 reflects the display light reflected by the first concave mirror 30 inside the housing 71, and projects the display light from the opening 71a of the housing 71 onto a projection area Rwf inside the vehicle cabin. The first concave mirror 30 and the second concave mirror 40 are magnifying mirrors that magnify and reflect the incident display light. For example, the first concave mirror 30 and the second concave mirror 40 may be aspherical mirrors (free-form mirrors) whose reflective surfaces are recessed into an aspherical shape (free-form shape).

[0015] In this way, the vehicle display device 1 uses three reflective members, which allows for a high magnification of the virtual image display and also allows for an increase in the viewing distance by extending the optical path length within the housing 71, which will be described later. On the other hand, while it becomes difficult to ensure the display quality of the virtual image when the optical path length is increased, the vehicle display device 1 uses aspherical mirrors (free-form mirrors) for two of the three reflective members, so it is possible to ensure the display quality of the virtual image.

[0016] The vehicle display device 1 includes a drive unit 50 that rotates the second concave mirror 40 to change the imaging position (display position) of the virtual image (see FIG. 1). The second concave mirror 40 is rotated around a rotation axis extending in the vehicle width direction to change the imaging position (display position) of the virtual image in the vertical direction of the vehicle. The drive unit 50 includes a motor 51 as a drive source, a power transmission mechanism 52 that operates with the output of the motor 51, and a rotary shaft 53 that rotates the second concave mirror 40 around its axis with the output of the motor 51 input via the power transmission mechanism 52, with the axial direction of the vehicle width (see FIG. 1).

[0017] The power transmission mechanism 52 may be one that directly applies a rotational torque corresponding to the output torque of the motor 51 to the rotation shaft 53. Alternatively, the power transmission mechanism 52 may be a power conversion mechanism that converts the output torque of the motor 51 into a linear force and applies this linear force to the second concave mirror 40, thereby rotating the rotation shaft 53 that is located at an eccentric position relative to the input point of the linear force. The rotation shaft 53 may be provided on the second concave mirror 40, or may be provided on a holding member that holds the second concave mirror 40.

[0018] This drive unit 50 rotates the second concave mirror 40 around the rotation axis 53, thereby changing the incident angle of the display light reflected from the first concave mirror 30 onto the second concave mirror 40, and also changing the emission angle of the display light reflected from the second concave mirror 40 toward the projection surface Rwf. By changing the emission angle of the display light from the second concave mirror 40 toward the projection surface Rwf, this drive unit 50 changes the imaging position (display position) of a virtual image related to the display light in the vertical direction of the vehicle.

[0019] The display light projected onto the projection area Rwf is reflected from the projection area Rwf to the eye point EP or the eye box EB, where it is visually recognized by the occupant as a virtual image (see FIG. 1). The eye point EP indicates the position of the occupant's eyes in the vehicle cabin. The eye box EB indicates the range of the eye point EP where the virtual image can be viewed.

[0020] The projection target Rwf refers to the windshield (here, the front windshield Wf) itself or a portion thereof (FIG. 1). The projection target Rwf may also be formed as a half mirror that receives display light from the second concave mirror 40 on a reflective surface, reflects it toward the eye point EP or the eye box EB, and emits light from outside the vehicle toward the occupants. For example, the projection target Rwf as a half mirror may be formed as a semi-transparent film conforming to the curved shape of the windshield (front windshield Wf) and attached to the interior wall surface of the windshield with an adhesive. The projection target Rwf as a half mirror may also be formed as a semi-transparent film conforming to the curved shape of the windshield (front windshield Wf) and sealed together with an intermediate film inside the laminated windshield. The projection target Rwf as a half mirror may also be a semi-transparent coating applied by painting or the like to the interior wall surface of the windshield (front windshield Wf). The projection target portion Rwf may be a combiner that covers the front windshield Wf from the inside of the vehicle compartment.

[0021] The vehicle display device 1 includes a control unit 60 (FIG. 1) that controls the operation of the display unit 10 and the drive unit 50. The control unit 60 controls, for example, the display information (display light) of the display unit 10. The control unit 60 also controls the output of the motor 51 to rotate the second concave mirror 40.

[0022] The vehicle display device 1 further includes a housing 71 that houses at least the display unit 10, the plane mirror 20, the first concave mirror 30, and the second concave mirror 40, and a transparent cover 72 that covers an opening 71a of the housing 71 (FIG. 1). In the vehicle display device 1, display light reflected by the second concave mirror 40 is emitted from the cover 72 to the outside of the housing 71 and projected onto a projection target Rwf located beyond the projection target Rwf. The vehicle display device 1 shown here is housed in an instrument panel Pi in the vehicle cabin with the cover 72 exposed, and projects the display light reflected by the second concave mirror 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 eyepoint EP or the eyebox EB.

[0023] In the vehicle display device 1, external light enters the housing 71 through the cover 72. The external light travels through the housing 71 in the order of the second concave mirror 40, the first concave mirror 30, and the plane mirror 20. Therefore, in the vehicle display device 1, if the external light is reflected by the plane mirror 20 toward the display 11 of the display unit 10, the display 11 may be affected by the infrared light and generate heat, which may reduce its durability.

[0024] Therefore, the vehicle display device 1 suppresses reflection of infrared light from the plane mirror 20, thereby suppressing heat generation in the display 11 due to the incidence of infrared light. Furthermore, since the P-polarized component of the display light (visible light) is less likely to be reflected in the projection area Rwf than the S-polarized component, the S-polarized component is the main component of the reflected light toward the occupant. Therefore, the vehicle display device 1 further suppresses heat generation in the display 11 by suppressing reflection of the P-polarized component from the plane mirror 20 toward the display 11.

[0025] Specifically, a mirror that transmits infrared light and the P-polarized component of visible light while reflecting the S-polarized component of visible light is used as the plane mirror 20. For example, the plane mirror 20 includes a light-transmitting, plate-shaped base plate 21 and a filter layer 22 that is provided on the wall surface of the base plate 21 facing the display unit 10 and that transmits infrared light and the P-polarized component of visible light while reflecting the S-polarized component of visible light ( FIG. 1 ).

[0026] In the vehicle display device 1, when external light enters the housing 71 and propagates to the plane mirror 20, the plane mirror 20 transmits infrared light and the P-polarized component of visible light, thereby suppressing heat generation in the display 11 of the display unit 10. Therefore, the vehicle display device 1 can improve the durability of the display unit 10.

[0027] In this vehicle display device 1, when display light is emitted from the display unit 10 toward the plane mirror 20, the plane mirror 20 transmits the P-polarized component of the display light (visible light), while the plane mirror 20 reflects the S-polarized component of the display light (visible light) toward the first concave mirror 30. Therefore, in this vehicle display device 1, the S-polarized component is reflected by the first concave mirror 30 and then the second concave mirror 40 and transmitted to the projection target Rwf. As described above, at the projection target Rwf, the main component of the reflected light directed toward the occupant is the S-polarized component. Therefore, this vehicle display device 1 can improve the durability of the display unit 10 without adversely affecting the virtual image display.

[0028] REFERENCE SIGNS LIST 1 vehicle display device 10 display unit 11 display device 20 plane mirror 21 base plate 22 filter layer 30 first concave mirror 40 second concave mirror 71 housing 71a opening Rwf projection target portion

Claims

1. A vehicle display device comprising: a housing; a display unit that emits display information into the housing as display light to be viewed as a virtual image by occupants in the vehicle cabin; a plane mirror that reflects the display light emitted from the display of the display unit inside the housing; a first concave mirror that reflects the display light reflected by the plane mirror inside the housing; and a second concave mirror that reflects the display light reflected by the first concave mirror inside the housing and projects the display light from an opening in the housing onto a projection target inside the vehicle cabin, wherein the plane mirror transmits infrared light and P-polarized components of visible light, while reflecting S-polarized components of the visible light.

2. The vehicle display device according to claim 1, wherein the plane mirror comprises a light-transmitting, plate-shaped base plate and a filter layer provided on the wall surface of the base plate facing the display unit, the filter layer transmitting the infrared light and the P-polarized component of the visible light while reflecting the S-polarized component of the visible light.

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