JP2022135583A - Head-up display for vehicle - Google Patents

Abstract

To provide a head-up display for a vehicle which reduces possibility that stray light is generated even when external light is incident.SOLUTION: A head-up display 1 is mounted on a vehicle C and displays a virtual image V at a position visible from a viewpoint EP of an occupant of the vehicle C, and includes: a display for emitting display light Li from a screen 23; an optical system having a correction mirror 31 and a concave mirror 32 as a mirror reflecting the display light Li; and a housing 50 having an opening 51 for emitting the display light Li upward. When a light beam connecting a center of the screen 23 and a center of a view point EP is set as a gut ray GR, the screen 23 is arranged at a position to be irradiated with external light SL incident from a windshield WS of a vehicle C, and is arranged so as to be inclined to the gut ray GR so that the external light SL reflected regularly on a surface of the screen 23 does not illuminate the optical system.SELECTED DRAWING: Figure 1

Description

The present invention relates to a head-up display mounted on a vehicle.

BACKGROUND ART As a conventional head-up display mounted on a vehicle, for example, a head-up display as disclosed in Patent Document 1 has been known. The head-up display (1) emits display light (L) to a windshield (2) to display a virtual image (V) so as to be visible from a viewpoint (4).

International Publication No. 2019-107294

However, in the configuration of Patent Document 1, when part of the sunlight passing through the windshield (20) and proceeding into the head-up display (1) is directly incident on the screen (80), the reflected light is reflected by the head. The configuration was such that the light could be reflected toward the optical members in the up display (1). Specifically, when the sunlight is reflected by the first concave mirror (16), it follows an optical path similar to that of the display light (L), so it reaches the viewpoint (4) and becomes stray light. It could be.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a vehicle head-up display that reduces the risk of generating stray light even when external light enters, focusing on the above-described problems.

In order to achieve the above object, a vehicle head-up display according to the present invention includes:
A vehicle head-up display that is mounted on a vehicle and displays a virtual image at a position visible from the viewpoint of an occupant of the vehicle,
a display that emits display light from a display surface;
an optical system having at least one mirror that reflects the display light;
a housing having an opening for emitting the display light upward;
When a ray connecting the center of the display surface and the center of the viewpoint is Gatley,
The display surface is
arranged at a position illuminated by external light incident from the windshield of the vehicle,
In addition, it is arranged at an angle to the Gatley so that the external light specularly reflected on the surface of the display surface does not illuminate the optical system.

The figure which shows the cross section of the head-up display for vehicles in this embodiment.

Hereinafter, a display device of the present disclosure and a vehicle head-up display device will be described as embodiments with reference to the accompanying drawings.

1. First Embodiment <1-1. About the configuration>
<1-2. About Screen 23>
<1-3. About Field Lens 22>
2. Modification

[1. First embodiment]
<1-1. About the configuration>
FIG. 1 is a cross-sectional view of a head-up display 1 (HUD 1), which is an example of a vehicle head-up display. The HUD 1 is arranged below the windshield WS of the vehicle C (for example, inside the instrument panel).

The HUD 1 emits display light Li and projects it onto the windshield WS. The display light Li is generated by illumination means and display means inside the HUD 1 . The generated display light Li is emitted from the opening 51 of the housing 50 by traveling through an optical system (a correction mirror 31 and a concave mirror 32, which will be described later). An occupant (user) can see a rectangular virtual image V at a position several meters to several tens of meters away from the windshield WS in the F direction by visually recognizing the display light Li reflected by the windshield WS from the viewpoint EP. .

A light ray connecting the center of a screen 23, which is an example of a display surface to be described later, and the center of an eyebox, which is the center of a space in which the virtual image V can be visually recognized, is called a gutray GR.

The virtual image V includes, for example, vehicle information such as the speed and engine speed of the vehicle C, route guidance displays such as turn-by-turn and maps, warning displays such as blind spot indicators and speed limit warnings, etc. Information that is highly necessary to call attention to is displayed. This provides a driving environment in which the need for eye movement and eye focal length adjustment is reduced. The virtual image V includes characters and icons indicating such information, as well as a background portion, and has, for example, a substantially rectangular shape when viewed from above by the occupant.

The HUD 1 includes a projector 21 , a field lens 22 , a screen 23 , a correction mirror 31 , a concave mirror 32 , a control board (not shown), a housing 50 and a cover glass 52 .

The projector 21, the field lens 22, and the screen 23 are one configuration example of a display that emits the display light Li from the display surface (screen 23), and are not limited to the following configuration.

The projector 21 emits projection light PL by a field sequential method, and is composed of a red light source, a green light source, a blue light source, a dichroic mirror, a DMD (Digital micro-mirror device), a prism, a projection lens (including an exit pupil), and the like. A known projector can be applied.

The red light source, the green light source, and the blue light source are composed of LEDs of respective colors, and are sequentially lit according to signals transmitted from an electrically connected control board. When turned on, each color light beam (illumination light) is emitted toward a dichroic mirror positioned in the upper direction of the drawing of each light source. Instead of using LEDs of different colors, it is also possible to use white LEDs in which transmission type color filters of each color are provided in the emission direction, or to use rotating transmission type color filters in which each color is evenly applied to the outer edge.

The dichroic mirror is a reflecting/transmitting member capable of transmitting or reflecting light of a predetermined wavelength range, and transmits/reflects each color light in the direction in which the DMD is positioned.

A DMD, which is a digital micro-mirror device, reflects light in a predetermined direction by changing the angles of minute mirrors arranged in a matrix on the plane of incidence of illumination light according to the control signal from the control board. It is a light modulation element. In this embodiment, each color ray transmitted/reflected by the dichroic mirror is reflected in the direction of the prism and other directions that do not affect the display of the virtual image V according to the angle of the mirror.

A prism is a prism held to transmit each color of illumination light incident on the DMD and to reflect each color light reflected from the DMD toward the projection lens.

The projection lens is composed of at least one lens, and emits the light reflected by the prism as projection light PL so as to form an image on the screen.

The projector 21 emits the projection light PL by selectively reflecting each color light source with the above configuration.

The field lens 22 is arranged in the vicinity of the screen 23 and is a lens that adjusts the light distribution of the projection light PL in order to sharpen the image of the peripheral portion in particular. Therefore, it is desirable that the screen 23 and the field lens 22 are provided at substantially parallel positions.

The screen 23 is a transmissive screen composed of a microlens array, a diffusion plate, and the like, and is a member that diffuses and transmits the projection light PL toward the correction mirror 31 as display light. The screen 23 emits the display light Li by being illuminated by the projection light PL.

With the above configuration, a display that emits display light Li from the display surface (screen 23) is configured.

The correcting mirror 31 and the concave mirror 32 constitute a reflecting optical system. The reflective optical system reflects the display light Li emitted from the screen 23 to the windshield WS.

Correction mirror 31 is, for example, a free-form surface mirror. The correcting mirror 31 is a mirror having a free-form curved surface that is concave in the longitudinal direction of the drawing and convex in the depth direction of the drawing. Due to this shape, the display light Li is reflected in the vicinity of the cross point CP so as to cross in the vertical direction of the drawing.

The concave mirror 32 is a reflecting member that magnifies the first display light and reflects it toward the opening (cover glass 52 ) of the housing 50 .

The mirrors that make up the optical system may have other modes.
For example, a multilayer interference film with different film thickness is formed on one side of a plate-shaped glass substrate by a method such as vapor deposition, and a cold mirror that transmits infrared light and reflects at least visible light, or a cold mirror that has polarization characteristics. It may be a mirror having a mirror or a normal plane mirror.

The cover glass 52 can be made of a plate-shaped transparent synthetic resin substrate with a uniform thickness, and can be made of, for example, PMMA or polycarbonate. The cover glass 52 is attached while curving so as to cover the opening of the housing 50 .

The control board includes a storage unit such as ROM and RAM (not shown) used for storage of predetermined programs and various data and storage areas during calculation, a CPU for performing arithmetic processing according to the predetermined program, and a microcomputer provided with an input/output interface and the like. Computer can be applied. The control board generates an image to be displayed on the display means, controls the display of the display means, and controls the illuminance of the lighting means, based on the vehicle information received from the external vehicle-mounted device.

The housing 50 is a container to which resin or metal moldings can be applied, and has an opening 51 for emitting the display light Li to the outside of the device, and a cover glass 52 is attached so as to cover the opening 51 . . Inside, the projector 21, the field lens 22, the screen 23, the correction mirror 31, the concave mirror 32, and the control board are fixed by known means such as fitting, locking, bonding with adhesive members, and screwing with screws.

<1-2. About Screen 23>
Conventionally, a display surface such as a screen or a liquid crystal display element has been provided at a certain angle with respect to Gatley. This is because the external light that has passed through the windshield WS and entered in the opposite direction along the optical path of the display light Li reaches the display surface via the optical system, travels again along the optical path of the display light Li, and reaches the viewpoint EP. This was to prevent Also from the viewpoint of display efficiency, providing an angle more than necessary has been avoided.

However, the inventor found that the external light SL may directly illuminate the display surface from the windshield WS through the opening of the HUD 1 depending on the layout.
In such a layout, the external light SL reflected by the screen illuminates the optical system, follows the optical path of the display light Li, and reaches the viewpoint EP, which may lead to deterioration of visibility.

Therefore, in the HUD 1 of the present disclosure, the screen 23 arranged at a position illuminated by the external light SL is arranged at an angle such that the external light SL specularly reflected on the surface of the screen 23 does not illuminate the optical system. .

In the vehicle head-up display shown in FIG. 1 configured in this way, even if the external light SL can directly illuminate the screen 23, the reflected external light SL follows the optical system and reaches the viewpoint EP. It prevents you from doing it.

In order to obtain the above effect, it is preferable that the display light Li is reflected along a plane including the longitudinal and vertical directions of the vehicle C, as in the HUD 1, and that the screen 23 faces upward of the vehicle. Easy to get the effect. This is because, in such a HUD, the display surface of the screen 23 is likely to be exposed to the external light SL. Therefore, with this configuration, it is easy to obtain the effects of the configuration of the present disclosure.

Moreover, it is desirable that the inclination of the screen 23 with respect to the gutley GR be provided within a plane including the longitudinal and vertical directions of the vehicle C. As shown in FIG. This is because the virtual image V often has a horizontally long rectangular shape from the viewpoint of visibility, and giving a tilt in this plane is equivalent to giving a tilt to the virtual image V in the short direction. According to this configuration, it is possible to direct the traveling direction of the external light SL reflected with a smaller amount of tilt than when the longitudinal direction is tilted to a location other than the optical system.
Note that the folding direction does not necessarily have to be strictly included in the front-rear and up-and-down directions, and may be included substantially in the front-and-rear and up-and-down directions. More specifically, it is sufficient if the normal line of the reflection point on the windshield WS is inclined in the horizontal direction of the vehicle, and is in a substantially vertical plane.

<1-3. About Field Lens 22>
As described above, the field lens 22 adjusts the light distribution of the projection light PL. Moreover, when the screen 23 is inclined with respect to the gutley GR, it is desirable that the field lens 22 is provided substantially parallel to the screen 23 .

As a result, the distance of the entire field lens 22 can be made closer to the screen 23, which is the imaging position of the projection light PL, and good optical performance can be exhibited for the entire peripheral portion of the screen 23. FIG. Optical performance particularly refers to suppression of dimming and blurring.

Moreover, it is desirable that the end surface 22 a be covered with the light shielding wall 53 .

In the configuration of the field lens 22 described above, the field lens 22 is arranged in a state of being greatly inclined with respect to the gutley GR. At this time, the end surface 22 a of the field lens 22 that is close to the projector 21 is likely to be exposed to the projection light PL of the projector 21 .

In particular, the vicinity of the end surface 22a located inside the bent display light Li complicates the structure of the housing 50 and makes it difficult to increase the strength. It is also difficult to cover or fix with the housing 50.
Not all of the projection light PL is used to display the virtual image V. FIG. Specifically, there is light unintentionally reflected or refracted inside the projector 21 in the outer peripheral portion of the projection light PL. Some of the light may reach the inclined field lens 22 (especially the end surface 22a).

For this reason, conventionally, the field lens 22 having the above configuration has a risk of refracting and reflecting the projection light PL in an unintended direction and generating stray light inside the HUD 1 when the end face 22a is illuminated by the projection light PL. was there.

Moreover, it is preferable that the end face 22a of the field lens 22, which is the end face corresponding to the upper end side of the virtual image V, be covered. This is because the inclination of the virtual image V is affected by the inclination of the screen 23, and it is desirable that the upper end of the virtual image V is inclined in the direction F. Conversely, if the upper end of the virtual image V falls in the direction B, it tends to be difficult to see when viewed from the viewpoint EP. This is thought to be due to the fact that human senses are generally not accustomed to visually recognizing such an upside-down image and that the inclination of the virtual image V approaches the direction opposite to the inclination of the road surface.

When the virtual image V is tilted in the direction F, the end surface of the field lens 22 corresponding to the upper end of the virtual image V moves toward the projector 21 .

Therefore, it is most desirable that the end surface 22a corresponding to the upper end side of the virtual image V is covered with the light shielding wall 53. FIG.
[2. Modification]

Although the vehicle head-up display of the present invention has been described with the configuration of the above-described embodiment as an example, the present invention is not limited to this, and the present invention can be applied to other configurations as well. Of course, various improvements and display changes are possible without departing from the above.

For example, although the projector 21, the field lens 22, and the screen 23 have exemplified the aspect which comprises a display, it is not restricted to this. For example, in Section 1-1, since the field lens 22 is not an essential configuration, a display using an electronic display such as a liquid crystal display element or an organic EL display element as a display surface may be applied.

Further, the projector 21 may adopt a mode in which LCOS (Liquid Crystal On Silicon) or TFT (Thin Film Transistor) is applied as an optical modulation element.

Moreover, a mode is shown in which the correction mirror 31 and the concave mirror 32 are applied as the mirrors constituting the optical system. However, they may also be other mirror members, for example plane mirrors or cold mirrors. In that case, the position of the end surface of the field lens 22 corresponding to the upper end of the virtual image V may change as a matter related to Section 1-2. For example, when the correction mirror 31 is changed from the configuration of the first embodiment to a plane mirror, the display light Li does not cross at the cross point CP and no vertical reversal occurs. tilt in the opposite direction. Specifically, it is preferable to rotate counterclockwise in the drawing from a state perpendicular to the gutley.

Moreover, a mode in which the projection light PL is directly projected onto the screen 23 has been shown. The projection light PL may be appropriately reflected by a mirror between the screen 23 and the projector 21 .

C Vehicle V Virtual image CP Cross point EP Viewpoint WS Windshield

PL projection light Li display light SL outside light GR Gatley

1 Head-up display (vehicle head-up display, HUD)
21 Projector 22 Field lens 23 Screen 31 Correction mirror 32 Concave mirror 50 Housing 51 Opening 52 Cover glass 53 Light shielding wall 54 Second opening

Claims (5)

A vehicle head-up display that is mounted on a vehicle and displays a virtual image at a position visible from the viewpoint of an occupant of the vehicle,
a display that emits display light from a display surface;
an optical system having at least one mirror that reflects the display light;
a housing having an opening for emitting the display light upward;
When a ray connecting the center of the display surface and the center of the viewpoint is Gatley,
The display surface is
arranged at a position illuminated by external light incident from the windshield of the vehicle,
and a head-up display for a vehicle, which is arranged to be inclined with respect to the Gatley so that the external light specularly reflected on the surface of the display surface does not illuminate the optical system. The display is
a projector having a light source, a light modulation element that modulates illumination light emitted by the light source to generate projection light, and a projection lens that includes an exit pupil through which the projection light passes;
a field lens that adjusts the light distribution of the projection light;
a screen, which is the display surface, emitting display light by imaging and diffusing the projection light;
has
The vehicle head-up display according to claim 1, wherein the field lens is provided substantially parallel to the screen. The vehicular head-up display according to claim 2, wherein an end surface of the field lens located near the projector is covered with a light shielding wall extending from the housing. The optical system is
a correction mirror that reflects the display light emitted by the display surface;
The vehicle head-up display according to claim 1, further comprising a concave mirror that reflects the display light reflected by the correcting mirror to the opening. The vehicular head-up display according to claim 1, wherein the optical system reflects the display light along a plane including substantially the longitudinal and vertical directions of the vehicle.

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