Vehicle display device

Abstract

To improve the durability of a display.SOLUTION: A vehicle display device comprises: a housing 71; a display unit 10 that emits, as display light in the housing 71, display information to be visually recognized as a virtual image by an occupant in a 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; and a second concave mirror 40 that reflects, in the housing 71, the display light reflected by the first concave mirror 30, and causes the display light to be projected from an opening 71a of the housing 71 to a section Rwf to be projected in the vehicle cabin. A mirror that transmits infrared light and a P-polarized light component of visible light and reflects an S-polarized light component of visible light is used for the planar mirror 20.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[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, and allows 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. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-30461 Summary of the Invention [Problem to be solved by the invention]

[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. [Means for solving the problem]

[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, wherein the plane mirror transmits infrared light and P-polarized components of visible light, while reflecting S-polarized components of the visible light. [Effects of the Invention]

[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 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. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing a vehicle display device according to an embodiment. [Figure 2] FIG. 2 is an explanatory diagram showing an example of the configuration of a plane mirror. DETAILED DESCRIPTION OF THE INVENTION

[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.

[0011] Reference numeral 1 in Fig. 1 indicates a vehicle display device of this embodiment. This vehicle display device 1 is a so-called head-up display device that displays information to be provided to occupants in the cabin of a vehicle (such as an automobile) as a virtual image. This vehicle display device 1 projects display light relating to the display information onto a projection surface Rwf such as a windshield in the cabin, and reflects the display light from this projection surface Rwf toward the occupants, thereby allowing the occupants to visually recognize 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 passengers in the vehicle cabin. The display unit 10 includes a backlight (not shown) and a light-transmitting, plate-like display 11, and transmits light irradiated from the backlight onto the display 11, causing the light to be emitted from the display 11 as display light for the 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 an 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 its 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 the 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 are aspherical mirrors (free-form mirrors) whose reflective surfaces are concave into an aspherical shape (free-form shape).

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

[0016] Here, 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 (FIG. 1). Here, the second concave mirror 40 is rotated around a rotation axis in the vehicle width direction to change the imaging position (display position) of the virtual image in the vehicle up-down direction. 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 being the vehicle width direction (FIG. 1).

[0017] The power transmission mechanism 52 may be a mechanism 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 positioned eccentrically with respect 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 eyepoint EP or eyebox EB, where it is visually recognized by the occupant as a virtual image (Figure 1). The eyepoint EP indicates the position of the occupant's eyes inside the vehicle. The eyebox EB indicates the range of the eyepoint EP where the virtual image can be seen.

[0020] The projection target portion Rwf refers to the windshield (here, the front windshield Wf) itself or a portion thereof (FIG. 1). The projection target portion 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 eyepoint EP or the eyebox EB, and emits light from outside the vehicle toward the occupants. For example, the projection target 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 attached to the interior wall surface of the windshield with an adhesive. The projection target portion Rwf as a half mirror may also 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 inside the laminated windshield. The projection target portion Rwf as a half mirror may also be a semi-transparent film that is coated, for example, on 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 that controls the operation of the display unit 10 and the drive unit 50 (FIG. 1). 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 closes 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 inside 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 also suppresses reflection of the P-polarized component from the plane mirror 20 toward the display 11, thereby further suppressing heat generation in 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 the 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 the vehicle display device 1, the S-polarized component is reflected by the first concave mirror 30 and then the second concave mirror 40, and is transmitted to the projection target Rwf. As described above, at the projection target Rwf, the main component of the reflected light toward the occupant is the S-polarized component. Therefore, the vehicle display device 1 can improve the durability of the display unit 10 without adversely affecting the virtual image display. [Explanation of symbols]

[0028] 1. Vehicle display device 10 Display Unit 11 Display 20 plane mirror 21 Base plate 22 Filter Layer 30 1st concave mirror 40 Second concave mirror 71 Case 71a aperture Rwf Projection area

Claims

1. The housing and a display unit that emits display information as display light into the housing, the display information being visually recognized as a virtual image by an occupant in the vehicle interior; a plane mirror that reflects the display light emitted from a display of the display unit within the housing; a first concave mirror that reflects the display light reflected by the plane mirror inside the housing; a second concave mirror that reflects the display light reflected by the first concave mirror inside the housing and projects the display light onto a projection target within a vehicle cabin through an opening in the housing; Equipped with The vehicle display device is characterized in that the plane mirror transmits infrared light and P-polarized light components in visible light, while reflecting S-polarized light components in the visible light.

2. 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 a 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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