JPH08295156A - Head-up display - Google Patents

Abstract

PURPOSE: To provide a head-up display which gives little stimulation to outside persons. CONSTITUTION: A head up display is provided in which a signal light 31 is diffracted and reflected by a hologram element 1 provided to a windshield 19, and a display information 85 is visualized. The hologram element 11 has plural selective wave length band areas, and the selective wave length band area of the hologram element 11 is set to make the reflected light almost to the color of a sky light, when the sky light 21 outside the car is reflected, and the ground angle θ of the reflected light 23 is made within 5 to 3 deg.. The reflected light 23 is favorable to form within the radius 0.03 by making the u' and v' color coordinates (0.18 and 0.40) as the center.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head-up display used in vehicles and the like.

[0002]

2. Description of the Related Art In ordinary driving of a vehicle, in order to confirm a speed display or the like, it is necessary to temporarily shift the line of sight from an outside scene to instruments on an instrument panel. Although this operation is indispensable for driving, it is a very troublesome operation. It is also said that frequent movements of the line of sight cause considerable fatigue to the driver. Therefore,
In recent years, there has been proposed a head-up display that uses a holographic optical element and can simultaneously visually recognize information necessary for driving such as speed and the external scene.

In this head-up display, a hologram combiner using a reflection hologram is used as a combiner for superimposing the plurality of optical information. The hologram combiner is provided with a diffraction characteristic that efficiently reflects only light in a specific selected wavelength band. As a result, the hologram combiner reflects the light emitted from the display (information light source) with high efficiency, while having a high transmittance for the light other than the above specific wavelength range, the light coming from the background is Most can be transmitted. As a result, the brightness of the outside scene seen through the hologram combiner and the display of the speed reflected by the hologram combiner are not impaired.

[0004]

However, a head-up display using a hologram combiner has the following problems. This is because outside light such as sunlight is diffracted / reflected by the hologram combiner for people or pedestrians in other vehicles (oncoming vehicles, etc.), and in particular, the specific color shown in the selected wavelength band. When the light is diffracted, it is recognized as a glaring, stimulating and unpleasant color. This is not preferable in terms of safety in oncoming vehicles.

In order to solve this problem, Japanese Patent Laid-Open No. 5-1
Japanese Patent No. 24456 proposes a method in which a plurality of selection wavelength bands of the hologram are provided and a neutral color is obtained when the lights of the plurality of selection wavelength bands are mixed.
However, this countermeasure has the effect of suppressing unpleasant reflected light when an external person views the hologram from a certain range of angles, but the angle selectivity of the light of the hologram makes it possible to use other angles. However, there is a problem that the color does not become neutral and the color becomes more conspicuous due to the plurality of selected wavelength bands. The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide a head-up display that effectively suppresses stimulating reflection of external light by a hologram to an external person.

[0006]

According to the present invention, a head-up display is constructed so that signal light recording display information is diffracted / reflected by a reflection hologram element provided on a windshield, and the display information is visually recognized in front of the windshield. In the case where the hologram element has a plurality of selected wavelength bands, the sky light outside the vehicle is diffracted / reflected, and the ground angle of the reflected light is in the range of 5 to 30 °,
The reflected light has more blue component (0.18,0) than the point of u'v 'chromaticity coordinate (0.201,0.461) of the standard light source C, which is generally represented by daylight on a cloudy day. .40), the selected wavelength band of the hologram element is set so that the radius is within 0.03.

What is most noticeable in the present invention is that the hologram element has a plurality of selected wavelength bands, and the tilt angle and the selected wavelength band of the hologram element in the head-up display are set as follows. Is. That is, considering the angle selectivity in the diffraction characteristics of the hologram element in advance, when the external light (skylight) is reflected and the angle to the ground (the angle formed with the horizontal line) is 5 to 30 °, the reflected light is mixed. It is to make the sky blue.

For example, when the ground angle of the reflected light is in the range of 5 to 30 °, the reflected light is represented by the u′v ′ chromaticity coordinate (0.20) which is generally regarded as the representative daylight on a cloudy day.
1, 0.461) has more blue component (0.1)
(8, 0.40) as the center and the radius is within 0.03. The smaller the number of selected wavelength bands of the hologram element for obtaining the diffracted / reflected light as described above, the better. Therefore, it is preferable that the number of selected wavelength bands is two. This is because generally, the smaller the number of selected wavelength bands is, the easier the hologram element can be manufactured and the higher the transmittance of the hologram element.

[0009]

In the head-up display according to the present invention, when the external light reflected by the hologram element has a ground angle of 5 to 30 °, the selected wavelength of the hologram element is adjusted so that the reflected light becomes substantially sky blue. Band has been set. Therefore, when an external person looks at the head-up display (hologram element) in the range of the line of sight where the ground angle is 5 to 30 °, the reflected light from the hologram element and the reflected light from the windshield are similar to the sky. It becomes a color and does not make people outside feel uncomfortable.

As shown in FIG. 1 to be described later, the angle of the line of sight of the person 82 outside who normally looks at the hologram element 11 of the head-up display is almost within the range of 5 to 30 ° to the ground angle. It is possible to visually recognize the hologram element 11 (hologram combiner) without a feeling of strangeness.

As the skylight, u'v 'chromaticity coordinate (0.201, 0.461) is known as a typical daylight on a cloudy day, and if the sunny day is taken into consideration, it is more than that. It is appropriate to use a bluish color, for example, (0.18, 0.40) as a reference. Therefore, it is preferable that the reflected light (hologram diffracted light) be within a radius of 0.03 centered on the coordinate (0.18, 0.40).

Further, the transmittance of the hologram element can be kept high by reducing the number of selected wavelength bands of the hologram element (two). Generally, when aiming at colorlessness (whitening), three or more wavelengths are mixed, but in the present invention, two wavelengths can be realized by limiting the reflection angle and setting the reference to bluish coordinates. That is, two wavelengths are set to the reference chromaticity coordinates (0.18, 0.4
It can be realized by taking 0) at opposite coordinates. As described above, according to the present invention, it is possible to provide a head-up display that effectively suppresses the stimulating external reflection of the hologram from an external person.

[0013]

In this example, as shown in FIG. 1, a signal light 31 having display information 85 recorded thereon is diffracted / reflected by a reflection hologram element 11 provided on a windshield 19, and a reproduction light 32 thereof reproduces the windshield 19. The head-up display 10 is configured to visually recognize the display information 85 in front of the head-up display 10. The hologram element 11 has two selected wavelength bands (blue and green) shown in Table 1.

[0014]

[Table 1]

As shown in FIG. 1, when the sky light (outside light) 21 outside the vehicle is diffracted / reflected by the hologram element 11 and the ground angle θ of the reflected light 23 is in the range of 5 to 30 °, The reflected light 23 is within a radius 0.03 (within the circle 63 of FIG. 2) from the point 65 (FIG. 2) of the chromaticity coordinate (0.18, 0.40) in the JIS u′v ′ chromaticity diagram. The selected wavelength band of the hologram element 11 is set as shown in Table 1.

A supplementary explanation will be given for each of them. Two kinds of interference fringes that are diffracted / reflected in a specific selected wavelength band shown in Table 1 are recorded on the hologram element 11. The hologram element 11 is manufactured using the optical system shown in FIG. That is, the light 35 emitted from the light source 41
Is split by a beam splitter 42, and mirrors 431, 43
2 and objective lens 441, 442 and then divergent light 361, 3
As the reference numeral 62, the hologram dry plate 15 is made incident at angles Φ ₀ and Ψ ₀ described later. Then, the wavelength of the light 35 emitted from the light source 41 is changed to generate a plurality of interference fringes on the dry plate 1.
5 on.

The hologram element 11 is mounted on the windshield 19 at an angle α to the ground. And the display 12
The signal light 31 emitted from is incident on the hologram element 11 at an incident angle Φ ₀ , is diffracted in the direction of the reflection angle Ψ ₀ , and
Enter the 1st eye. The signal light 31 is monochromatic light that belongs to one of the above two selected wavelength bands.

When an external person 82 views the head-up display 10 from the outside of the vehicle, the angle Ψ ₁ formed by the line of sight 83 with respect to the normal line of the hologram element 11 is different from the reflection angle Ψ ₀ of the signal light 31. Therefore, when the external light 21 enters the hologram element 11 at the incident angle Φ ₁ and enters the eyes of an external person 82 along the line of sight 85, the wavelength of the selected wavelength band for the hologram element 11 changes from λ _n to λ according to the following equation. shift to _n '. (SinΦ ₀ −sinΨ ₀ ) λ _n ⁻¹ = (sinΦ ₁ −s
in Ψ ₁ ) λ _n ′ ^-1

In the head-up display 10 of this embodiment, the ground angle θ of the line of sight 83 of the outside person 82 is 5 to 3 after the shift according to the above-mentioned conditional expression is expected in advance.
When it is within the range of 0 °, the skylight emits the hologram element 11
The reflected light 32 diffracted / reflected by is set to fall within the chromaticity range of the circle 63 shown in FIG. That is, in this example, the ground angle α of the hologram element is 34 degrees, the incident angle Φ ₀ of the signal light 31 is 50 degrees, and the exit angle Ψ ₀ is 64.5 degrees. The band is set to the value shown in Table 1.

Under these conditions, when the ground angle θ of the line of sight of the person 82 outside is actually changed between 5 ° and 30 °, the outside light 2
It was confirmed by an experiment that the reflected light 23 for visually recognizing 1 changes along the curve 64 shown in FIG. 2 and falls within the circle 63. Therefore, the outsider 82 is the windshield 1
Light (light inside the circle 63) similar to the skylight reflected by 9 is visually recognized as reflected light of the hologram element 11. Therefore, the hologram element 11 does not feel uncomfortable.

Further, since the line-of-sight angle of 5 to 30 ° covers most of the position of the eyes of the person 82 outside, the head-up display 10 causes the person 82 outside to feel uncomfortable during the daytime when the external light is strong. The phenomenon that gives the As described above, according to this example, it is possible to provide the head-up display 10 that effectively suppresses the stimulating reflection of external light on the hologram element 11 with respect to the person 82 outside.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a head-up display according to an embodiment.

FIG. 2 is a diagram showing reflected light from a hologram element visually recognized by an external person in the head-up display of the embodiment.

FIG. 3 is an optical system diagram of an exposure process of the hologram element of the example.

[Explanation of symbols]

 10. ． ． Head-up display, 11. ． ． Hologram element, 19. ． ． Windshield, 21. ． ． Skylight (outside light), 23. ． ． Reflected light (external light), 31. ． ． Signal light, 85. ． ． Display information,

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Emiko Hirayama 1-1, Showa-cho, Kariya city, Aichi Prefecture, Nihon Denso Co., Ltd. (72) Toru Mizuno 1-1-1-1, Showa town, Kariya city, Aichi prefecture Incorporated (72) Inventor Yasuo Hagiri 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Automobile Co., Ltd.

Claims (2)

[Claims] 1. A head-up display configured such that signal light recording display information is diffracted / reflected by a reflection hologram element provided on a windshield, and the display information is visually recognized in front of the windshield. The hologram element has multiple selected wavelength bands,
When the sky light outside the vehicle is diffracted / reflected and the angle of the reflected light to the ground is in the range of 5 to 30 °, the reflected light is
U′v ′ of the standard light source C that is generally represented by daylight on a cloudy day
A radius of 0.0 from the point (0.18, 0.40) where the bluish component is larger than the point on the chromaticity coordinate (0.201, 0.461)
A head-up display, wherein the selected wavelength band of the hologram element is set so as to be within 3. 2. The head-up display according to claim 1, wherein the selected wavelength band of the hologram element is composed of two bands.