JPH07172213A - Head-up display device - Google Patents

Abstract

PURPOSE:To provide a head-up display device prevented from flare-up light by preventing the external light incident from outside a car from reflecting on the surface of the inside glass plate of the car. CONSTITUTION:This device is a head-up display device in which a combiner 2 consisting of a hologram for diffracting a beam of light including the information from a lumunescent display means toward a driver is disposed on the windshield of a vehicle and a reflection preventing layer 13 is provided on the surface inside the combiner 2 in the vehicle.

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 (hereinafter referred to as HUD) device, and more particularly to a HUD in which flare light from outside the vehicle is reduced.

[0002]

2. Description of the Related Art HUD has recently been used as a method of displaying information to a driver in an automobile or the like.
This is because the optical information projected from the information projection means such as a liquid crystal display device is projected on a combiner composed of a hologram or a half mirror incorporated in the windshield of an automobile, etc., and the driver almost moves the viewpoint from the driving state. The information can be read without any need.

In particular, a hologram using a hologram as a combiner can have a lens function and the like as well as a function of diffracting optical information toward the driver.
It is possible to diffract optical information in the direction of the driver's visual field, or to form an image at any position without using any other optical system such as a lens, and without impairing the foreground brightness. It is effective as a combiner for HUD because it has a feature that a high-intensity display image can be obtained.

FIG. 3 is a conceptual diagram showing an example of a conventional HUD. The light 43 including the information to be displayed, which is emitted from the light source 46 and passed through the transmissive liquid crystal display element 45 via the lens system 44, is applied to the hologram 42 provided on the windshield 47 of the vehicle body and is diffracted to be transmitted to the driver. It is visually recognized at the observation position 41.

The lens system 44 has a function as a collimator, and the function is the hologram 4.
It can be attached to 2 and speed display 48, warning display 49
It is also possible to form the display image of (1) in the distance.

Further, since the hologram 42 has a wavelength selection function, an image of a desired color can be displayed. Usually, the color is often single, but multi-color display by multiple exposure is also possible, and the amount and quality of display information can be improved. For example,
By setting the speed display 48 in green and the warning display 49 in red, it becomes possible to more accurately transmit information to the driver.

As such a holographic combiner, a reflection type hologram is usually used. In the production of the reflection hologram, one side of the photosensitive material surface of the hologram is irradiated with reference light and the other side is irradiated with object light. Then, a diffraction grating is manufactured.

Inside the hologram photosensitive material, these two
The two laser beams interfere with each other to produce light and dark interference fringes, which are recorded as a diffraction grating based on the difference in physical properties such as the refractive index or density of the photosensitive material. In this type of reflection hologram, when the incident angle of light and the reflection diffraction angle are different, the diffraction grating surface is inclined with respect to the hologram surface and is not parallel to the surface.

FIG. 2 is a conceptual sectional view showing a hologram enclosed in the windshield. Reference numeral 22 is a reflection hologram that functions as a combiner. Inside the hologram 22, a diffraction grating having an inclination with respect to the surface as shown in the figure is formed. The hologram 22 is provided on the windshield inner glass 23 and is made of polyvinyl butyral (P
Together with the intermediate film 25 made of VB), it is enclosed inside the vehicle outside glass 24 to form a safety laminated glass. The interface 21 between the intermediate film 25 and the hologram 22 is a protective layer so that the characteristics of the hologram are not affected by the plasticizer contained in the intermediate film.

The light 26 containing the information emitted from the light emitting display means is incident on the inside glass 23 at an angle θ ₁ , is refracted due to the difference in refractive index between air and glass, and is θ inside the glass.
The angle is ₁ '. The light entering the glass is reflected and diffracted by the hologram 22 toward the driver. Since the diffraction grating inside the hologram is tilted with respect to the surface, the glass internal angle of the diffracted light becomes θ ₂ ', which is refracted at the glass surface and is emitted at an angle θ ₂ inside the vehicle and emitted as light 27 as an observer such as a driver To be seen. Generally, θ ₁ and θ ₂ are different in order to prevent a double image due to reflected light on the glass surface outside the vehicle, and in a passenger car, θ ₁ <θ ₂ due to the positional relationship between the light source, combiner and driver.

[0011]

[Problems to be Solved by the Invention] Such hologram HU
When the external light 28 indicated by the dotted line enters a vehicle equipped with D, if the incident angle θin is at a certain angle, the external light reaches the surface of the vehicle interior glass at θ ₁ 'and again θ
_{At 1} ', it reflects like 31 toward the inside of the glass. Since this angle is the same as the angle of the light 26 containing information inside the glass, the external light is reflected and diffracted by the hologram 22 and is emitted from the glass surface inside the vehicle at an angle θ ₂ .
The light 27 containing information arrives at an observer such as a driver 29. The noise light due to this external light is called flare light. As can be seen from FIG. 2, if the surface of the inside glass 23 and the surface of the outside glass 24 are parallel, θin ′ and θin
_{Since 1} 'becomes equal, the incident angle outside the glass is θin =
In the case of θ ₁ , flare light will be observed. While the windshield of a general vehicle is a curved shape, it is considered to flare light is observed in the case of general .theta.in = theta ₁ as a guide since the curvature is not so large.

When such flare light is generated, it may appear as bright unevenness or as a spot-like bright spot depending on the incident angle of light from the outside of the vehicle, which may reduce the visibility of the display image of the HUD. Bring Especially, when sunlight is observed as flare light, the brightness is high, which may cause dazzling, which is a safety problem. In addition, weak lights such as street lights, which are not noticeable in the daytime due to the dark surroundings at night, were observed as flare lights, which was very annoying when driving. Since this flare light is observed at an angle different from that when an external light source such as the sun or a street light is viewed linearly, one light source can be seen by a plurality of eyes, which is very annoying.

[0013]

The present invention has been made to solve the above problems, and provides a HUD having the following features.

A light emitting display means which includes at least a light source and a display body which displays information to be displayed and which emits information to be displayed as light, and a windshield of the vehicle which is provided with an observer in the vehicle. A head-up display vapor deposition device comprising at least a combiner made of a hologram diffracting toward a head-up display device, characterized in that an antireflection layer is provided inside the vehicle than the combiner. Is.

[0015]

When the HUD according to the present invention is used, the anti-reflection layer is provided on the innermost surface of the windshield and the combiner, so that the outside glass 28 shown in FIG. No reflection on the surface of 23,
The reflected light 31 observed as flare light is not generated.
Therefore, it is possible to effectively reduce the generation of flare light due to external light.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a conceptual diagram showing an example of the HUD of the present invention. A light emitting display means is provided below the windshield 7, and the light emitting display means transmits light emitted from a light source 6 using a hot cathode tube through a lens system 4 which is a collimator, and a transmission type color liquid crystal display element. The light 3 emits the information to be displayed which has passed through the display body 5 consisting of. The light 3 is applied to the combiner 2 made of a hologram arranged on the windshield 7 of the vehicle body, diffracted, and visually recognized by the driver at the observation position 1. The windshield 7 is made of laminated glass in which two glass plates are adhered via an interlayer film made of polyvinyl butyral or the like, and the combiner 2 made of a hologram is also provided between the two glass plates.
Is enclosed. Further, an antireflection layer 13 is provided on the vehicle interior surface of a portion of the two glass plates of the windshield 7 corresponding to the portion where the combiner 2 of the glass plate on the vehicle interior side is arranged.

The lens system 4 has a function as a collimator, and this function can be added to a hologram, so that the display images of the speed display 8 and the warning display 9 can be formed at a distance. It will be possible.

If desired, another hologram or lens for aberration correction may be arranged between the display body 5 and the combiner 2.

Further, since the hologram has a wavelength selection function, an image of a desired color can be displayed, and further, multi-exposure or stacking of a plurality of holograms enables multi-color display, and the quantity and quality of display information. Can be improved. In this embodiment, 545 nm and 6 corresponding to the emission peak wavelength of the hot cathode tube are used.
Using a multiple exposure hologram that diffracts 12 nm light,
The speed display 8 is displayed in green, and the warning display 9 is displayed in amber (orange) or the like by mixing green and red. As a result, it becomes possible to transmit information to the driver more accurately.

In this embodiment, the windshield inclination θw is 35.
And the angle of incidence θ of the light 3 containing information on the hologram 2.
_The hologram was exposed so that ₁ was 40 ° and the emission angle θ ₂ was 60 °, and the hologram was enclosed in a windshield. In this arrangement, the incident angle of external light generated by flare light is approximately θ in = θ ₁ = 4
The incident angle is 0 °, and considering the inclination of the glass, the incident angle is 15 ° above the horizontal.

In this embodiment, the antireflection layer 13 having substantially the same size as that of the combiner is provided on the inner surface of the inner glass plate. As a result, even if the light 11 from the upper light source 10 such as the sun or a street light is incident, it does not reflect on the vehicle inside surface of the vehicle inside glass plate and travels straight as shown by 12. Therefore, the external light 11 was not observed by the driver 1 as flare light, and the generation of flare light could be prevented.

In this embodiment, the antireflection layer having substantially the same size as that of the combiner is provided, but it may be larger than that and may be provided on the entire surface. However, in view of cost, it is desirable that the size is the minimum necessary. Further, as the antireflection layer, magnesium fluoride MgF ₂
A single-layer antireflection film having (refractive index n = 1.38) was used. The thickness d is an optical thickness nd, and is preferably λ / 4 with respect to the central wavelength λ at which the reflectance is minimum. In this embodiment, the hologram diffracts the light of 545 nm and the light of 612 nm, so nd = 580/4 = 145 nm is set so that the reflectance at λ = 580 nm is the lowest in the middle. Further, in order to reduce the reflectance in a wider wavelength range, a multi-layer antireflection film such as a two-layer antireflection film made of zirconium oxide ZrO ₂ and magnesium fluoride, or a three-layer antireflection film to which aluminum oxide Al ₂ O ₃ is further added. A preventive film may be used. A similar antireflection layer can also be obtained by a method in which an organic metal material is provided in a predetermined size by screen printing or the like and then heat treatment is performed instead of the vapor deposition film.

The hologram usually has an area of about several 10 mm to several 100 mm square and a thickness of several μm to several 10 μm. Although such a hologram is desirable in that a volume / phase type hologram such as a Lippmann type can obtain high diffraction efficiency, a hologram called an embossed type or a rainbow type can be widely used. Further, as the hologram material, a photopolymer such as polyvinylcarbazole or acrylic is used.
Various light-sensitive materials such as dichromated gelatin, photoresists and silver salts can be used.

In this embodiment, a horizontal width of 150 is used as a combiner.
A volume phase reflection hologram was used using a photosensitive material made of an acrylic photopolymer having a size of mm × length 200 mm and a thickness of 20 μm.

The hologram is arranged on the windshield, and may be provided on the surface of the windshield (outer surface of the vehicle) or the inner surface of the vehicle, for example, in view of protection of the hologram. As in the example, it is preferable to use it by enclosing it inside the windshield which is a laminated glass.
Of course, if the hologram is arranged on the vehicle interior surface of the windshield, the antireflection layer must be provided on the hologram vehicle interior surface. Further, at this time, when the hologram protective layer is provided on the inner surface of the hologram, the antireflection layer may be provided on at least one surface of the protective layer.

The light emitting display means in the present invention has a function of emitting light to display, and a hot cathode tube (HC) is attached to a display body composed of a so-called light receiving display element such as a liquid crystal display element.
T), a cold cathode tube, a fluorescent display tube (VF), a halogen lamp, an LED, or the like for irradiating light emitted from a light source, or may have these functions together.

When the combiner of the present invention is used for color display, the liquid crystal display element includes a color nematic liquid crystal display element including a transmission type twist nematic liquid crystal element and a super twist nematic liquid crystal display element. It can be preferably used, and light emitted from one light source can be irradiated as light of a desired color.

In this way, the lights of a plurality of colors can be emitted from the same light emitting display means, and when the lights of a plurality of colors are simultaneously displayed, the display images are displayed in an overlapping manner, and conversely, In order to prevent overlapping of displayed images, a combination of a color filter and a light source or a color liquid crystal display element may be controlled as necessary so that light of a plurality of colors is not simultaneously irradiated.

Alternatively, instead of using the light receiving type display element, the light source itself may be patterned and arranged to generate specific information as light. In the case where the light source is used together with the light receiving display element, an appropriate light collimating means such as a lens system or a curved reflecting mirror, and a suitable light guiding means such as a light guide plate are provided between the light receiving display element and the light source. You may arrange. Further, if necessary, an optical polarization means or KNO is provided in the optical path until the light is projected on the hologram.
Non-linear optical elements such as ₃ may be arranged.

Further, when the HUD of the present invention is displayed in color, if the distance from the combiner to the display image is the same for each color, color display can be performed on the same plane, and if the display is changed depending on the color, the display color depends on the display color. It is possible to obtain three-dimensional images with different observed distances of the display image.

[0031]

According to the present invention, since the antireflection layer is provided on the surface inside the vehicle rather than the combiner, even if external light enters from outside the vehicle, it does not reflect on the surface of the glass inside the vehicle and goes straight through. Therefore, the reflected light inside the glass that causes the flare light to be observed is not generated. Therefore, it is possible to effectively reduce the generation of flare light due to external light.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an example of a HUD of the present invention.

FIG. 2 is a conceptual cross-sectional view for explaining a hologram and a flare light generation mechanism enclosed in a windshield.

FIG. 3 is a conceptual diagram showing a conventional HUD.

[Explanation of symbols]

1: Driver's observation position 2: Combiner 3: Light containing information 4: Lens system 5: Display element 6: Light source 7: Windshield 8: Speed display 9: Warning display 10: External light source such as the sun 11: Flare light Incident direction 12: External light that is not observed as flare light and goes straight through 13: Antireflection layer

Claims (1)

[Claims] 1. A light emitting display unit which includes at least a light source and a display unit which displays information to be displayed, and which emits information to be displayed as light, and a windshield of a vehicle, which is provided with the light inside the vehicle. A head-up display vapor deposition device comprising at least a combiner made of a hologram that diffracts toward an observer, wherein an antireflection layer is provided inside the vehicle with respect to the combiner.