JPH07215091A - Head-up display - Google Patents

Abstract

PURPOSE:To obtain a head-up display which can prevent the incidence of external light at an angle for generating the flare light on the first hologram and suppresses the generation of the flare light. CONSTITUTION:A head-up display is constituted so that the first hologram 26 which diffracts the light including the information transmitted from a light emission display means toward an observer is arranged on a windshield glass laminate 6, and the second hologram 22 which is interposed between the light emission display means and the first hologram 26 and diffracts the light supplied from the light emission display means at the larger angle than the critical angle of incidence is arranged on the laminated glass 6.

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).

[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. 11 is a conceptual diagram showing an example of a conventional HUD. The light 87 emitted from the light source 81 and passing through the transmissive liquid crystal display element 83 via the lens system 82 and containing information to be displayed is reflected by the aberration correction hologram 84 and is provided on the windshield 86 of the vehicle body. Illuminated at 85, diffracted and observed by the driver at the observation position 88
Is visible at.

The lens system 82 has a function as a collimator, and the function is the hologram 8.
It can also be provided in 4 or 85. Further, if the hologram 84 or 85 is provided with a magnification, the display images of the speed display 89 and the warning display 90 can be formed in a distant place.

Further, since the holograms 84 and 85 have a wavelength selection function, an image of a desired color can be displayed.
Usually, the color is often single, but multi-color display by holograms that have been subjected to multiple exposure is also possible, and the amount and quality of display information can be improved. For example, by setting the speed display 89 to green and the warning display 90 to 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 type hologram, one surface of the photosensitive material surface of the hologram is irradiated with reference light and the other surface thereof 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. 6 is a schematic sectional view showing a hologram enclosed in the windshield. Reference numeral 46 is a reflection hologram that functions as a combiner. Inside the hologram 46, a diffraction grating having an inclination with respect to the surface as shown in FIG. 6 is formed. The hologram 46 is provided on the windshield inner glass plate 43, and is enclosed inside the outer glass plate 44 together with the intermediate film 45 made of polyvinyl butyral (PVB) to form a safety laminated glass. The interface 47 between the intermediate film 45 and the hologram 46 is a protective layer that prevents the hologram characteristics from being affected by the plasticizer contained in the intermediate film.

The light 41 containing information emitted from the light emitting display means is incident on the glass plate 43 on the inside of the vehicle at an angle θ ₁ ,
Refraction occurs due to the difference in refractive index between air and glass, and becomes an angle of θ ₁ 'in the laminated glass. The light entering the laminated glass is reflected and diffracted by the hologram 46 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 'and it is refracted at the surface of the glass plate and emitted at an angle θ ₂ inside the vehicle, and
8 is visually recognized by an observer such as a driver. Generally, θ ₁ and θ ₂ are different in order to prevent a double image due to the reflected light on the outside glass plate surface, 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 external light 92 from a light source 91 such as the sun or a street light shown in FIG. 11 enters a holographic combiner 85 at a specific angle in a vehicle equipped with D, the external light is the information-containing light 8
Reach the driver as at 93 with 7. The noise light caused by the outside light is called flare light. The cause of generation of flare light can be understood as follows. When the external light 49 shown by the dotted line in FIG. 6 is incident, when the incident angle θ _in is a certain angle, the external light is θ with respect to the surface of the vehicle interior glass.
It arrives at ₁ 'and again at θ ₁ ' reflects toward the inside of the glass plate as 50. Since this angle is the same as the angle of the light 41 containing information inside the glass, the external light is reflected by the hologram 46.
Is reflected and diffracted by the vehicle interior glass plate surface angle θ ₂
The external light reaches the observer such as the driver 51 together with the information-containing light 48 at 51.
As can be seen from FIG. 6, if the surface of the inner glass plate 43 and the surface of the outer glass plate 44 are parallel, θ _in 'and θ ₁ '
Are equal, so the incident angle outside the glass is θ _in = θ ₁
In this case, flare light will be observed. The windshield of a general vehicle has a curved surface shape, but its curvature is not so large, so that flare light is considered to be observed when θ _in and θ ₁ are almost equal.

The above description is for the case where the wavelength of the external light 49 is equal to the wavelength of the light 48 containing the information diffracted by the hologram 46. Since general outside light includes light in a wide wavelength range, it may be considered that flare light is generated by including wavelengths that satisfy the above conditions. Moreover, the incident angle θ of the external light 49
_{Even if in} is slightly deviated from θ ₁ , if light having a wavelength satisfying the so-called diffraction Bragg condition is included in the external light 49, a part of the external light 49 is diffracted by the hologram 46 and the light 48 containing information. It will proceed in a direction slightly deviated from. If the direction does not deviate significantly from the visual range of an observer such as a driver, it will be observed as flare light.

When such flare light is generated, it may appear as bright unevenness or as spot-like bright spots depending on the incident angle of light from the outside of the vehicle, which adversely affects the visibility of the display image of the HUD. Bring In particular, when sunlight is observed as flare light, the brightness is high, which may cause dazzling, which is a safety issue.
In addition, since the surroundings are dark at night, weak lights such as street lights that cannot be noticed during the day are also observed as flare lights, which is 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.

Further, as described above, since the conventional holographic HUD diffracts light of a specific wavelength, when the driver looks outside through the hologram, the color of the transmitted light is a color corresponding to the diffraction wavelength of the hologram. It is the complementary color of (display color). That is, when the display color is only green as shown in FIG. 7, colorless light 62 from the outside (also called white light, but hereinafter, white light is generically called colorless light, and white is also colorless. When passing through the hologram 61, it is partially reflected and diffracted by the diffraction grating inside the hologram, and the reflected light 63 becomes green. Therefore, the transmitted light 64 becomes magenta (pink to red) which is the complementary color of the transmitted light 64, and the driver 65 feels it as an irritating and unpleasant color. Further, as a result, the color tone of the background is affected, and the visibility of the condition outside the vehicle such as the road during driving is impaired, which is a safety issue.

On the other hand, as shown in FIG. 8, outside light 72 is applied to an observer 75 (a pedestrian or a driver of an oncoming vehicle) outside the vehicle.
Due to the angle dependence of the diffraction wavelength of the diffraction grating inside the hologram 71, the reflected color of the color changes greatly from red (observation near the front) 73 to green (oblique observation) 74 depending on the angle of observation, which also gives an unpleasant impression and results in a combiner. As a result, there was a problem that the designability and commercialability of the vehicle equipped with it were impaired.

FIG. 9 is a chromaticity diagram showing a simulation result of the color change of the reflected color. Chromaticity diagram is JIS-Z
The color is quantitatively expressed by the chromaticity coordinates x and y defined by 8701. The point X shown as a light source in FIG. 9 represents colorless. The closer the color of the hologram is to this point, the more colorless it becomes, and the more preferable the color is for the observer.

However, regarding the color of the reflected light of the monochromatic hologram used in the conventional HUD, for example, the diffraction condition of the hologram is such that the wavelength is 545 nm, the diffraction efficiency is 60%, and the half width is 15 n.
In the case of m, it changes like a black diamond mark in FIG. That is, it turns out that the color near the front becomes red, and as it becomes oblique, it changes greatly to orange, yellow, and green.
When viewed from the front, it becomes a stimulating color, red, and when viewed obliquely, it becomes a glare green with high visibility, giving an unpleasant impression to the observer.

In order to improve the color tone of the reflected light for the observer outside the vehicle, the Japanese Patent Laid-Open No. 4-110984 discloses a first hologram for improving the color tone of the reflected color by the first hologram used for display. Although a HUD is disclosed in which a second hologram that reflects a color close to the complementary color of the hologram is stacked or multiple-exposed, the HUD cannot be completely improved because it is composed of two-color holograms. Especially, the wavelength often used as a display color is 500 to 560 nm.
As for the green light, it has a drawback that it is actually difficult to improve the color tone of the reflected color because there is no light of the wavelength corresponding to the complementary color. There was nothing else.

Further, in JP-A-3-179418, in order to improve the color tone of light transmitted through a combiner,
A wavelength λ that is a complementary color to the reflection wavelength λ ₁ of the hologram for display.
_A HUD is disclosed in which an optical element for reflecting or attenuating the _second light is combined. However, since it is color-corrected by the two-color configuration like the above-mentioned known example, it cannot be completely improved against the green light. It has the same drawbacks and is only a means of improving only the color tone of transmitted light.

Further, in Japanese Patent Application Laid-Open No. 4-291221, in order to improve the color tone of the transmitted light of the combiner even with respect to green light, light in a wavelength range complementary to the reflection wavelength λ ₁ of the hologram for display is used. Although a HUD that combines optical elements that reflect or attenuate multiple wavelength ranges that can combine light is disclosed, it is an improvement only for the color tone of transmitted light, so it is effective only at a specific angle connecting the hologram and the observer. The color tone of the reflected light of the hologram was not necessarily improved for the observer outside the vehicle. For example, in the disclosed embodiment, in order to improve the color tone of the transmitted light of the hologram that diffracts the light of 530 nm, a hologram that diffracts the light of 460 nm and 630 nm that can synthesize the complementary color of the light of 530 nm is used. It shows a transmission characteristic diagram having an efficiency of about 90% and a half value width of about 10 nm. A color tone simulation of the reflected color of the combiner observed outside the vehicle based on this characteristic is as shown in FIG. 10. It can be seen that the oblique observation makes the color relatively yellow, but the front observation turns yellow green.

As described above, it has been proposed to use a plurality of holograms in order to improve the color tones of the reflected light and the transmitted light of the holographic combiner. However, in principle, the hologram utilizes the diffraction phenomenon. However, the appearance color could not be sufficiently improved by these improvement methods.

Further, when the three-color hologram is used as described above, the light incident from the outside of the vehicle is reflected and diffracted in the wavelength bands corresponding to the three colors, so that the light transmitted to the inside of the vehicle is reduced. By law, the vertical transmittance of visible light is 70.
%, But it is not easy to satisfy this requirement when three-color holograms are enclosed in laminated glass, and the diffraction efficiency of the hologram is suppressed to about 60% or less depending on the wavelengths of the three colors. It has to be. Therefore, there is a problem in terms of the brightness of the display image.

In the HUD using the hologram, due to the diffraction effect, a halogen lamp or a fluorescent display tube (VF) is used.
When a light source having a wide spectrum half width such as D) is used, chromatic aberration occurs, the displayed virtual image is blurred, and the visibility is deteriorated. In order to correct it, it has been proposed to use a second hologram for aberration correction as indicated by reference numeral 84 in FIG. In addition to the hologram, when using an optical element having a lens function such as a lens or a curved mirror,
Even if the incident light is monochromatic light, the display virtual image may be blurred or distorted. Even in that case, there is some effect by optimizing the exposure conditions of the hologram, and it becomes possible to prevent these aberrations by using a hologram for aberration correction similar to chromatic aberration.

Therefore, in the conventional hologram HUD, it is necessary to use the aberration correction hologram 84 in addition to the combiner 85, and the size of the entire system becomes large. The system from the light source 81 to the hologram 84 usually has to be housed in the dashboard, but the space inside the dashboard is very small, and there are many restrictions, and there is a problem in mounting the hologram HUD.

[0025]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art, and includes at least a light source and a display for displaying information to be displayed, and information to be displayed. Is arranged on a windshield of a vehicle, which is made of laminated glass in which at least two glass plates are adhered via an intermediate film, and the light is emitted toward an observer in the vehicle. In the head-up display including at least a combiner made of the first hologram, the laminated glass has a glass inside or outside the laminated glass, which is emitted from the light emitting display means and enters the laminated glass. A second hologram is provided which diffracts the light traveling toward the surface of the plate to be larger than a critical angle at which the light is totally reflected on the surface of the glass plate. The light incident on the inside laminated glass is diffracted by the beam is radiated toward the first hologram,
A head-up display characterized by being diffracted toward an observer by a first hologram.

[0026]

When the HUD according to the present invention is used, the incident angle θ ₁ ′ of the light including the information incident from the glass plate toward the hologram is larger than the critical angle at which the total reflection on the inside surface of the inside glass plate occurs. Therefore (ie, because it is larger than the critical angle at which the glass plate on the outside of the vehicle is totally reflected on the outside surface)
Θ _in 'corresponding to the incident angle of flare light which is almost equal to ₁ '
Is also larger than the critical angle (hereinafter, unless otherwise specified, the critical angle of total reflection on the vehicle interior surface of the vehicle interior glass plate or the vehicle exterior surface of the vehicle exterior glass plate is simply referred to as the critical angle). The light inside the laminated glass that enters the surface of the glass plate at an angle larger than the critical angle is totally reflected in principle and cannot be transmitted to the outside of the laminated glass. In other words, in principle, the light outside the laminated glass cannot enter at an angle larger than the critical angle. Therefore, since the external light does not enter at an angle observed as flare light, it is possible to effectively reduce the generation of flare light. This means that even if outside light includes light in a wide wavelength range, flare light generation can be suppressed if θ ₁ 'is sufficiently larger than the critical angle.

When an observer outside the vehicle sees the reflection color of the hologram for the same reason, the angle at which the light diffracted by the hologram enters the glass plate outside the vehicle is larger than the critical angle in most of the observation angle range. Therefore, it is not emitted outside the vehicle and is not observed. When the angle is smaller than the critical angle in the other angle regions, the diffraction wavelength becomes longer and becomes the infrared region, which cannot be perceived by the outside observer. Therefore, the appearance reflection color of the first hologram can be effectively improved.

The external light transmitted from the outside of the vehicle to the inside of the vehicle through the first hologram is a hologram which is exposed by light of a plurality of wavelengths corresponding to a plurality of colors selected so that the color tone thereof becomes close to colorless. Therefore, the observer in the car feels that the color tone is almost colorless.

When light is vertically incident on a laminated glass having a hologram, the wavelength diffracted by the hologram is in the infrared region and cannot be detected, so that the hologram is substantially transparent and the visible light transmittance is not lowered. . Therefore, even a highly efficient three-color hologram can sufficiently satisfy the regulation of the visible light vertical transmittance.

Furthermore, in the HUD of the present invention, the windshield has a second hologram for allowing light to enter the first hologram at an angle larger than the critical angle, and the second hologram has an aberration correcting function. By combining them together, the aberration correction hologram that was required between the windshield and the light source is no longer needed, the system size on the light source side is significantly reduced, and the problem of storage in the dashboard is solved. .

In the present invention, in order to totally reflect the light containing information inside the laminated glass, the angle of the light containing information incident on the laminated glass is changed by the second hologram. From the point of view, it is usual that the first hologram and the second hologram are arranged in parallel in the vertical direction of the vehicle. In this case, the second hologram may be arranged in the vicinity of the first hologram where the diffracted light is arranged so that the observer can easily see the diffracted light, but in the present invention, the second hologram is diffracted by the second hologram. Since the light containing information can be totally reflected inside the laminated glass, the second hologram can also be arranged at an inconspicuous position of the laminated glass. In particular, flare light can be prevented by providing a ceramic color concealing layer on the outer side of the second hologram of the laminated glass corresponding to the second hologram so as to block external light from entering.

At this time, since the glass plate surface is totally reflected, even if the inside of the laminated glass is reflected plural times, there is no problem of energy loss due to the reflection. Moreover, as described above, the second hologram serving as the aberration correction hologram can be arranged without the second hologram interposed between the windshield and the light source.

[0033]

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 laminated glass 6, and the light emitting display means is a transmissive color liquid crystal display device in which light emitted from a light source 1 using a hot cathode tube is passed through a lens system 2 which is a collimator. The information to be displayed which has passed through the display body 3 consisting of is emitted as light 7. The laminated glass 6 is formed by adhering two glass plates through an intermediate film, the first hologram 26 is enclosed in the laminated glass 6, and the first hologram 26 is further included.
The second hologram 22 is encapsulated below.
The light 7 emitted from the light emitting display means is irradiated and diffracted on the second hologram 22 enclosed in the laminated glass 6, is totally reflected and propagated inside the laminated glass 6, and then is irradiated on the first hologram 26. , Diffracted and observed by driver 8
Is visible at.

From the glass plate inside the vehicle to the first hologram 26
Since the incident angle θ _in 'of the light entering toward is larger than the critical angle at the interface between the glass and the air, the light including the information from the light emitting display means has an angle corresponding to the internal angle θ _in ' as it is. It cannot be directly illuminated from inside the car. Therefore, in this embodiment, the second hologram 22 is used for incidence. The second hologram 22 is disposed below the hood so that external light does not directly enter the second hologram 22, and the ceramic color concealing layer 1 is provided.
It is shielded from the outside of the vehicle by 1.

The lens system 2 has a function as a collimator and is particularly effective in the case of a spot-shaped light source such as a halogen lamp. Further, the hologram 22 or 26 can be provided with a magnifying function, and the display images of the speed display 9 and the warning display 10 can be formed at a distance. A lens or a curved mirror may be used if necessary.

Further, since the hologram has a wavelength selecting function, an image of a desired color can be displayed, and further, multiple exposure or stacking of a plurality of holograms enables multicolor display, and the quantity and quality of display information. Can be improved. In this embodiment, multiple exposure holograms that diffract light of 545 nm and 612 nm corresponding to the emission peak wavelength of the hot cathode tube and light of 460 nm for making the color tone of the external light passing through the hologram close to colorless are used, and the speed indication 9 is displayed. Green, warning display 10
Was displayed as amber (orange) in which green and red were mixed. As a result, it has become possible to transmit information to the driver more accurately.

The hologram usually has an area of about several tens of mm to several hundreds of mm square and a thickness of about several μm to several tens of μm. Such a hologram is desirable in that a volume phase type hologram such as a Lippmann type hologram can obtain high diffraction efficiency, but a hologram called an emboss type hologram or a rainbow type hologram can be widely used. As the hologram material, various photosensitive materials such as polyvinyl carbazole, acrylic-based photopolymers, dichromated gelatin, photoresists, and silver salts can be used.

For example, when the light including the information reflected and diffracted by the second hologram is totally reflected by the inner side surface of the vehicle interior glass plate and then enters the second hologram again, unnecessary diffracted light may be generated. Especially, the thickness of laminated glass is usually 5 m with two glass plates with a thickness of about 2 mm and an interlayer film.
Since the second hologram is as thin as about m, if the second hologram exceeds several hundred mm square (depending on the angle of total reflection, it exceeds 300 mm square), the light including the information totally reflected by the glass plate on the inside of the vehicle is re-generated. It may be incident on the second hologram. Therefore, if the size of the second hologram is small to some extent (a few hundreds of 10 mm square), it is possible to prevent the totally reflected light from entering the second hologram again.

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 120 mm and a thickness of 20 μm.

Further, in the case of producing a hologram exposed by light of a plurality of wavelengths corresponding to a plurality of colors selected so that the color tone of external light transmitted from the outside of the vehicle to the inside of the vehicle through the hologram is close to colorless, It is preferable to triple-exposure a single photosensitive material as in the embodiment, but it is of course not a problem to stack individually exposed holograms on a plurality of photosensitive materials. Further, it is also an effective method to stack a plurality of photosensitive materials having different wavelength bands to be exposed in advance and to expose at a plurality of wavelengths.

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 type 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 HUD in the present invention is used for color display, the liquid crystal display element is preferably a color liquid crystal display element including a color filter and a transmission type twisted nematic type liquid crystal element, a super twisted nematic type liquid crystal display element, or the like. It can be used and the 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 can be displayed in an overlapping manner. On the contrary, in order to prevent the overlapping of the displayed images, a combination of a color filter and a light source or a color liquid crystal display element may be controlled as necessary to prevent light of a plurality of colors from being 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. It is possible to obtain three-dimensional images with different observed distances of the display image.

FIG. 2 is a schematic sectional view of the main part of the HUD of this embodiment.
Shown in. As described above, the first hologram 26 of this embodiment is used.
Uses a triple exposure hologram that diffracts light of 545 nm and 612 nm corresponding to the emission peak wavelength of the hot cathode tube and 460 nm for making the color tone of transmitted light of external light closer to colorless. The diffraction efficiency was about 60%, and the half width was about 15 nm. Further, the laminated glass 6 is filled with a second hologram 22 for allowing light to enter the first hologram 26 at an angle larger than the critical angle. The second hologram 22 has 5
Double-exposed holograms are used to diffract light of 45 nm and 612 nm. The diffraction efficiency was about 80%, and the half width was 15 nm.

The incident angle θ ₁ of the light which is incident on the second hologram 22 from the light emitting display means is 30 °, and the incident angle θ ₁ ′ which is incident from the glass plate 23 on the inside of the vehicle toward the second hologram is glass. Refractive index about 1.52, air about 1.0
Since it is 0, according to Snell's law, θ ₁ '= sin
⁻¹ ((sin30 °) /1.52) ≈19.2 °. The critical angle at the interface between glass and air is sin ^-1 (1.0
0 / 1.52) ≈41.1 °. Therefore, the second
By making the reflection diffraction angle θ ₃ ′ from the hologram of 4 greater than 41.10, θ ₃ ′ becomes larger than the critical angle. Note that if water drops adhere to the surface of the glass plate in rainy weather, etc., the condition for total reflection may collapse, so θ ₃ 'is 4
It is preferable to take a value considerably larger than 1.1 °.
Specifically, the refractive index of water is about 1.33, and sin ^-1
Since (1.33 / 1.52) ≈61.0 °, θ
It is desirable that ₃ '> 61.0 °. In this embodiment, θ ₃ ′ = 70 ° is set with a margin.

The light diffracted by the second hologram 22 propagates after being totally reflected a plurality of times inside the laminated glass, that is, on the inside surface of the inside glass plate and the outside surface of the outside glass plate. It enters the hologram 26 of No. 1 at θ ₃ ′. The reflection diffraction angle of the first hologram 26 was set to θ ₂ = 60 ° in consideration of the installation position of the first hologram 26 and the observation position of the driver. Therefore, the incident angle θ ₂ ′ that diffracts the first hologram and is directed toward the inside surface of the inside glass plate 23 is θ ₂ ′ = sin ⁻¹ ((sin 60 °) / 1.
52) ≈ 34.7 °.

The holograms 22 and 26 of this embodiment are adhered to the outer surface of the inner glass plate 23 of the laminated glass 6, and together with the intermediate film 25 made of polyvinyl butyral,
A windshield is enclosed inside the outside glass plate 24 of the vehicle. The interface between the intermediate film 25 and the holograms 22 and 26 is a protective layer 27 that prevents the hologram characteristics from being affected by the plasticizer contained in the intermediate film. A polyvinyl alcohol film was used as the protective layer.

The flare light is generated in the HUD when the light is incident from the direction such that θ _in '= θ ₃ ' as described above. However, in this embodiment, θ _in '= θ
_Since 3'is larger than the critical angle between glass and air, the condition of total reflection is satisfied as in 29, and light from the outside cannot enter at an angle corresponding to θ _in '. Therefore, flare light cannot be generated. Even if the external light includes light in a wide wavelength range and is incident from any angle, since θ ₃ 'is set to 70 °, which is sufficiently larger than the critical angle, flare light generation can be effectively prevented.

Further, in the first hologram of this embodiment, the reflection color when viewed by an observer outside the vehicle is also dramatically improved. When the external light 30 is incident as shown in FIG. 2, the external light 31 reflected and diffracted by the first hologram 26 is totally reflected by the surface of the glass plate 24 on the outside of the vehicle and cannot be emitted to the outside of the vehicle again. In the external light 32 incident at another angle, the light reflected and diffracted by the first hologram 26 may be emitted to the outside like 33. However, the diffraction wavelength at that time is lengthened by the Bragg condition. Since it is in the infrared region, it cannot be perceived by an observer outside the vehicle. Therefore, an external observer cannot see the reflected diffracted light by the first hologram even if the light is incident at any angle.
The reflected color of the first hologram is substantially colorless.

FIG. 4 is a chromaticity diagram showing how the color tone of the reflected and diffracted light of the hologram of this embodiment changes. The reflection color of the hologram shown by the black rhombus is colorless, which is almost the same as the chromaticity of the light source shown by X even if the observation angle is changed in the vertical plane. Slightly to the right (red region) of the light source, the diffracted light from the hologram that diffracts 460 nm at the incident setting angle θ ₃ 'has a longer wavelength due to the Bragg condition, but it is not completely in the infrared region but slightly This is because it is observed as red. This can be easily prevented by increasing the diffraction wavelength of the blue hologram or further increasing the internal angle θ ₁ '.

The color tone of the light 35 from the outside of the vehicle, which is transmitted through the first hologram 26 and observed by the driver, is a hologram exposed by the three primary colors of red, green and blue so that the color tone becomes closer to colorless. Since it is used as the first hologram, it is almost colorless.

Further, in the present embodiment, the visible light vertical transmittance was also improved. Light incident vertically is hologram 2
The wavelength diffracted by 6 has a longer wavelength due to the Bragg condition, and the light is in the infrared light range that cannot be perceived by human eyes. Since the visible light vertical transmittance is a numerical value corrected by the visibility of human eyes, it can be said that the hologram is substantially transparent. In this embodiment, the outer glass plate is 2 mm.
2mm thick glass inside the car using thick bronze glass
Thick transparent glass was used. The visible light vertical transmittance in the case of no hologram is about 82%, but it is about 80% even in the portion provided with the first hologram, which sufficiently satisfies the regulation (70%).

As the second hologram of this embodiment,
By using the one exposed so as to minimize the amount of aberration such as chromatic aberration, blur, and distortion due to the first hologram 26, the aberration correction hologram is not required on the light source side in the dashboard. Therefore, the size of the entire system can be significantly reduced.

When external light is incident on the second hologram 22 from a direction as shown by 36 in FIG. 6, the external light is diffracted by the second hologram 22 and the light 28 containing information is within the visual field of the driver. It reaches to and becomes flare light. However, by disposing the second hologram below the hood and providing the ceramic color concealing layer 37 on the outside of the vehicle to shield external light as in the present embodiment,
It was possible to effectively prevent the generation of flare light due to the second hologram.

HU in the second to fourth embodiments of the present invention
FIG. 3 shows a schematic sectional view of a main part of D. In these examples, the first hologram 26 has 545 nm, 612 nm and 433 nm corresponding to the emission peak wavelength of the hot cathode tube.
A triple-exposure hologram that diffracts light is used. The diffraction efficiency was about 60%, and the half width was about 15 nm. The hologram photosensitive material is exposed so that the incident angle θ ₃ ′ of the light incident from the inside glass plate 23 or outside glass plate 24 toward the first hologram is 75 ° and the diffraction angle θ ₂ is 60 °. First hologram 2
It was set to 6. In these embodiments, a display body made of a color liquid crystal is used together to form a HUD for full color display.

A colored glass plate is often used as the glass plate on the vehicle exterior side of the laminated glass for its design and absorption of heat rays. In that case, the intensity of light including information that propagates by being reflected inside the laminated glass is attenuated by absorption in the colored glass plate. As a means for preventing this attenuation, it is conceivable to propagate only the inside of the non-colored glass plate inside the vehicle.

In the second embodiment shown in FIG. 3A, the second
The reflection type hologram 22 is used as the hologram of the same as in the first embodiment. The light including information diffracted by the second hologram 22 at an angle θ ₃ '= 75 ° larger than the critical angle is propagated by totally reflecting only the inside of the uncolored glass plate 23 on the inside of the vehicle to prevent attenuation. It is diffracted by the third reflective hologram 38 arranged on the glass plate 23 on the inside of the vehicle. Since the hologram 38 is a regular reflection hologram having an entrance / exit angle larger than the critical angle, and is exposed at a plurality of wavelengths so that the color tone of the transmitted color becomes closer to colorless,
There are no problems with flare light, reflected color, transmitted color, and visible light transmittance. The light finally enters the first hologram 26 and diffracts to the driver as 28.

In FIG. 3B of the third embodiment, the reflective second hologram 22 and the transmissive first hologram 26 are shown.
Is used. The light diffracted by the second hologram propagates after being totally reflected inside the laminated glass, and then diffracted by the first hologram 26 to reach the driver as light 28.

In the fourth embodiment, as shown in FIG. 3C, the transmissive second hologram 22 shielded from the outside by the ceramic color concealing layer 37 from the outside of the vehicle is provided on the inside surface of the glass plate 23 on the inside of the vehicle. The light is totally reflected and propagates only inside the vehicle inside glass plate 23 by using the reflection-type third hologram, and the light is diffracted by the reflection-type first hologram 26 so that the light is reflected as 28. Reach the driver. In this case, it is preferable that a transparent protective film (not shown) that protects the second hologram is attached to the vehicle inner surface of the second hologram 22.

By making the entrance / exit angle of the third hologram larger than the critical angle, there is no problem of flare light, reflected color, or visible light for the same reason as the first hologram. Regarding the transmitted color, there is still no problem by exposing the photosensitive material of the third hologram with light of a plurality of wavelengths so that the color tone of the transmitted color approaches colorless.

In common with these embodiments, the problems of flare light, reflected color, transmitted color, visible light transmittance and system size are solved as in the first embodiment. Further, since the internal incident angle θ ₃ 'to the first hologram is 75 °, which is larger than that in the first embodiment, the change of the reflected color of the external light is as shown in the chromaticity diagram of FIG. , And became more colorless than in the first example. Further, the color tone of the transmitted light of the external light can be made almost colorless because the hologram of triple exposure corresponding to the three primary colors of red, green and blue is used. As for the visible light vertical transmittance, it was possible to secure about 80% as well as the first embodiment, and it was possible to sufficiently exceed 70% of the regulation.

As described above, the four examples of the present invention have been illustrated, but it goes without saying that the present invention is not limited to these. For example, in the case of totally reflecting the light on the outer surface of the outer glass plate as in the third embodiment, a transmissive hologram is used as the second hologram for diffracting the light from the light emitting display means for that purpose. You may use.

The hologram in the present invention is arranged on laminated glass, and when a transmissive hologram is used, it may be stuck on the surface of the laminated glass (the surface on the inside of the vehicle). In view of the point, it is preferable to use it by enclosing it inside the laminated glass. When the hologram is attached to the vehicle interior surface of the laminated glass, it is preferable that a transparent protective film (not shown) is laminated on the vehicle interior surface of the hologram.

When the hologram is affixed to the vehicle interior surface of the laminated glass, a transparent protective film is laminated on the vehicle interior surface to protect the hologram. In this case, it suffices that the transparent protective film has a size enough to cover the entire surface of the hologram, and even if the transparent protective film is slightly larger than the size of the hologram or has a size enough to be laminated on the entire surface of the windshield. There is no particular limitation. Also,
As the transparent protective film, it is preferable to use a material having a refractive index that is substantially the same as the refractive index of glass in view of the visibility of the driver or the like. In this case, since the incident angle of the light including information incident on the hologram is larger than the critical angle of total reflection on the vehicle outer surface of the transparent protective film, flare light is also prevented from being generated by the transparent protective film. .

The transparent resin film itself, which is used for safety glass obtained by laminating a transparent resin film made of polyurethane or the like and having a self-repairing property on the entire surface of a glass plate, may be used as the transparent protective film. It is possible. Laminated glass usually refers to two glass plates adhered with an intermediate film interposed therebetween, but when the above safety glass is also included in the laminated glass, the outside glass plate and the above transparent resin film are included. When the hologram is enclosed between the transparent resin film and the glass plate on the outside of the car, the transmission type and the reflection type holograms are diffracted toward the observer, and the light containing information is totally reflected multiple times. Both of these can be used.

Further, the hologram may be arranged so as to come into contact with the glass plate outside the vehicle, and when it is enclosed in the laminated glass, one of the glass plate inside and outside the vehicle is taken into consideration in view of the ease of manufacturing. It is preferable to bring them into contact with. In particular,
When propagating light containing information only inside the glass plate on the inside of the vehicle, the hologram containing light is arranged so as to be in contact with only the glass plate on the inside of the car, so that the light containing information can also propagate through the interlayer film. It is preferable because it does not exist.

[0069]

According to the present invention, the light emitting display means is
Since the incident angle of the light incident on the first hologram via the hologram is larger than the critical angle, the external light does not enter at the angle at which the flare light is generated, and the generation of the flare light is effectively suppressed. Can be obtained. Also, regarding the color tone of the reflected color by the first hologram, since the above-mentioned incident angle is larger than the critical angle, the diffracted light does not go out of the vehicle, and even if it goes out, the light has a long wavelength and becomes an infrared region. Because it cannot be sensed by humans,
The reflection color of the hologram can be made almost colorless. Further, regarding the color tone of the transmitted light of the first hologram of the external light, since the hologram exposed by the light of the plurality of wavelengths corresponding to the plurality of colors selected so as to make the color tone close to colorless is used, it is almost colorless. Can be By using the hologram thus exposed as the first hologram, the HU in the present invention is
It is also easy to make D a color HUD for multicolor display. Furthermore, the vertical transmittance of the visible light has little influence because the diffraction wavelength of the vertically incident light by the hologram is in the infrared region, and the standard of the regulation can be easily satisfied.

Further, in the present invention, the second hologram for making the light incident on the first hologram at an angle larger than the critical angle is used, and the second hologram is caused by the blurring, distortion, and the like of the display virtual image caused by the first hologram. By providing the function of correcting chromatic aberration, it is not necessary to separately provide a hologram for aberration correction that has been conventionally proposed on a dashboard or the like, and it is possible to significantly reduce the size of the light source system.

In the HUD of the present invention, since the diffracted light from the second hologram is totally reflected and propagated in the laminated glass, it is possible to avoid spatial overlap between the second hologram and the first hologram. .

Particularly when colored glass is used as the vehicle outside glass plate, since the third hologram for propagating only in the uncolored vehicle inside glass plate is used, light attenuation can be prevented.

Similar to the first hologram, the third hologram has the same entrance / exit angle as the critical angle and is exposed at a plurality of wavelengths so that the color tone of the transmitted color is close to colorless. For this reason, there is no problem with flare light, reflected color, transmitted color, or visible light transmittance.

Further, a second hologram is provided outside the vehicle.
By providing a ceramic color concealing layer on the laminated glass so that external light that does not enter the hologram of
Generation of flare light due to the second hologram can also be prevented.

[Brief description of drawings]

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

FIG. 2 is a schematic sectional view showing an example of a main part of a HUD according to the present invention.

FIG. 3 is a schematic sectional view of a main part of a HUD according to the present invention.

FIG. 4 is a chromaticity diagram showing an example of changes in the reflection color of the HUD of the present invention.

FIG. 5 is a chromaticity diagram showing another example of changes in the reflection color of the HUD of the present invention.

FIG. 6 is a schematic cross-sectional view for explaining a hologram and a flare light generation mechanism enclosed in a windshield.

FIG. 7 is a conceptual diagram illustrating a transparent color of a hologram.

FIG. 8 is a conceptual diagram illustrating a reflection color of a hologram.

FIG. 9 is a chromaticity diagram showing an example of changes in the reflection color of a conventional HUD.

FIG. 10 is a chromaticity diagram showing another example of changes in the reflection color of a conventional HUD.

FIG. 11 is a conceptual diagram showing a conventional HUD.

[Explanation of symbols]

 1: Light source 2: Lens system 3: Display element 6: Laminated glass 7: Light containing information 8: Driver's observation position 9: Speed display 10: Warning display 11: Ceramic color hiding layer 22: Second hologram 26: First hologram

Claims (10)

[Claims] 1. A light-emitting display means that includes at least a light source and a display body that displays information to be displayed and that generates information to be displayed as light, and at least two glass plates are bonded via an intermediate film. A head-up display provided with at least a combiner composed of a first hologram arranged on a windshield of a vehicle made of laminated glass and diffracting the light toward an observer in the vehicle, wherein the laminated glass has: A second hologram that diffracts light emitted from the light emitting display means and incident on the laminated glass and then traveling from the inside of the laminated glass toward the surface of the glass plate on the inside or outside of the vehicle by a larger amount than a critical angle at which the glass plate surface totally reflects the light Is disposed, and the light that is diffracted by the second hologram and enters the laminated glass is directed toward the first hologram. It is a head-up display, characterized in that it is diffracted toward the viewer by the first hologram. 2. A third hologram, which specularly reflects the light diffracted by the second hologram toward the vehicle inner glass plate, is enclosed in the laminated glass between the second hologram and the first hologram. The head-up display according to claim 1, wherein the head-up display is provided. 3. The third hologram is a hologram exposed by light of a plurality of wavelengths corresponding to a plurality of colors selected so that the color tone of the external light transmitted from the outside of the vehicle to the inside of the vehicle through the hologram becomes close to colorless. The head-up display according to claim 2, wherein the head-up display is provided. 4. The first hologram is a transmissive hologram, and the light, which is enclosed in the laminated glass and totally reflected on the outer surface of the outer glass plate of the laminated glass, is transmitted and diffracted toward an observer. The head-up display according to any one of claims 1 to 3, wherein 5. The head-up display according to any one of claims 1 to 4, wherein the first hologram is a transmissive hologram and is attached to the surface of the laminated glass on the inside of the vehicle. 6. The first hologram is a reflection hologram, and the light, which is enclosed in the laminated glass and totally reflected by the inner surface of the inner glass plate of the laminated glass, is reflected and diffracted toward an observer. The head-up display according to any one of claims 1 to 3, wherein 7. A second outer glass plate of the laminated glass
7. The head-up display according to any one of claims 1 to 6, wherein a ceramic color concealing layer is laminated on a portion corresponding to the hologram of above and outside the second hologram. 8. The critical angle is a critical angle at an interface between air or water and a glass plate, which is determined by a refractive index of air or water and a refractive index of glass.
One of the heads-up displays. 9. The first hologram is a hologram exposed by light of a plurality of wavelengths corresponding to a plurality of colors selected so that the color tone of the external light transmitted from the outside of the vehicle to the inside of the vehicle through the hologram becomes close to colorless. The head-up display according to claim 1, wherein the head-up display is provided. 10. The second hologram is a hologram exposed so as to minimize the amount of aberration of a display virtual image formed by the first hologram.
Head-up display of any of ~ 9.