JP3321849B2 - hologram - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hologram.

[0002]

2. Description of the Related Art Conventionally, there is an increasing need for a head-up display for an automobile which improves visibility by, for example, enlarging a speed display or the like in front of a windshield using a hologram. And with the rise of this need, a hologram with less noise has been desired.

For this reason, conventionally, Japanese Patent Application Laid-Open No. 62-806
As disclosed in Japanese Patent Application Laid-Open No. 87-87, when a hologram is exposed, an anti-reflection film is formed on the surface of the hologram element facing the substrate, and exposure is performed to obtain a good hologram element in which noise is not recorded. It is known that a good reproduced image is obtained by removing the protective film.

[0004]

However, in recent years,
Despite the necessity of further noise reduction, the configuration of the hologram itself is further complicated, and there is a contradictory tendency that noise is likely to occur. It was not easy to get.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a hologram having a configuration capable of obtaining hologram reproduction light with sufficiently reduced noise.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention provides an optically transparent first member having one surface and the other surface facing each other, and the one surface of the first member. A hologram element on which interference fringes are recorded as a recording medium, and the hologram element of the first member
Are provided on one surface side on which the
One surface and a second member having the other surface.
The second member is in contact with one surface of the second member.
On the other surface side of the first member at the boundary surface with the air
Absorbs light that has entered and transmitted through the hologram element.
A hologram having an anti-scattering film having a function of a hologram is employed.

In the embodiment of the present invention, the second member may be called a cover member because it covers the substrate having the hologram element, and the second member and the first member may be called cover members. can is mentioned in general glass such as soda glass, various plastic materials such
You.

[0008] scattering preventing film, when light is directed toward the surface of the second member passes through the hologram element of the first member, the second
Has a function of absorbing the light at the boundary surface between the surface of the member and the atmosphere so that the light does not go to the hologram element again. Further, the antireflection film, when the light incident from the surface toward the third member in the direction of the substrate has a function of preventing reflection of light at the interface between the surface side and the atmosphere of the third member .

In order to form a film capable of absorbing black or dark light, the anti-scattering film may be, for example, a binder made of a synthetic resin such as epoxy, melanin or acrylic.
A pigment to which a pigment such as black is added may be used. The anti-scattering film may be made of a black paint or a tape if there is no problem in durability and use environment. On the other hand, as the antireflection film, MgF ₂ , TiO ₂ ,
ZrO _{2 and the} like, and these may be formed as a single layer or a combination thereof to form a multilayer.

It is desirable that each member has the same refractive index as that of the dichromated gelatin film constituting the hologram element, and the refractive index is, for example, in the range of 1.5 to 1.6.

As the sealant, it is desirable to use an ultraviolet-curable or thermosetting optical organic resin such as epoxy or acrylic, which is the same as or close to each of these members . The sealant is set to improve the moisture resistance of the hologram element, and the seal width is set according to the water absorption of the sealant itself and the environmental conditions of the hologram. The seal width refers to a portion filled only with the sealant, and is shown in FIG.

The hologram element is constituted by exposing a photosensitive agent such as photopolymer, emboss, gelatin dichromate, agar, egg white and the like. Of these, dichromated gelatin is particularly desirable. As a recording medium to be recorded on the hologram element, when the element has a function as a magnifying glass, as in the embodiment described later,
It is a lens, and of course, letters, numbers, and pictures may be recorded as a recording medium.

Further, a laser beam is used at the time of exposing the photosensitive agent, but the pitch of the interference fringes of the object recorded on the photosensitive agent can be changed by changing the incident angle of the laser beam with respect to the photosensitive agent. Thus, the wavelength reproduced by the hologram element can be changed based on the relationship of Bragg reflection. As a result, the hologram element
Filter function can be added. Further, by recording interference fringes having different pitches on the photosensitive agent, and by causing white light to enter the hologram element, several colors can be reproduced.

In the present invention, optically transparent means not only completely transparent but also translucent and opaque.
In this case, the condition is that light can be transmitted.

[0015]

According to the present invention, by adopting the above structure, the surface reflection and the scattering of the transmitted light of the hologram element which cause noise of the hologram can be reduced by the second member (the first cover member) and the third member (the first cover member). (The second cover member).

[0016]

As described above, it is possible to obtain a high-quality display image with sufficiently reduced noise.

[0017]

FIG. 1 is a sectional view of a hologram 1 according to the present invention, and FIG. 2 is a plan view of FIG. 1 and 2, reference numeral 2 denotes a transparent glass substrate, which is a first member of the present invention, having large surfaces facing each other,
A hologram element 1a is provided on one surface. In the element 1a, a recording medium composed of interference fringes is recorded by exposing a photosensitive agent to light. As described later, the recording medium is a concave lens as a magnifying glass. The hologram element 1a records interference fringes of two different pitches of 290 nm and 320 nm by changing the incident light of the laser beam on the photosensitive agent. That is, as the shape of the interference fringes, two types of interference fringes having a curvature are recorded in order to simultaneously record the concave lens and the color information.

Reference numeral 3 denotes a cover plate made of transparent glass, which is a third member , having large surfaces facing each other. The cover plate 3 is arranged such that one surface thereof is opposed to the other surface of the substrate glass 2 which is not provided with the hologram element 1a and which is in contact with the atmosphere, and that the entire surface of the other surface is antireflection. A film 5 is formed.

Reference numeral 4 denotes a cover plate made of transparent glass as a second member , and has large surfaces facing each other. The cover plate 4 is arranged such that one surface side thereof is opposed to the one surface side of the substrate glass 2 to which the hologram element 1a is provided, and the entire surface of the other surface side in contact with the atmosphere prevents scattering. A film 6 is formed.

Reference numeral 7 denotes a sealant which is filled between the substrate glass 2 and the cover plate 3 and between the hologram element 1a and the cover plate 4 of the substrate glass. The element 1a is protected against the humidity of the surrounding environment.

Light is incident on the hologram 1 of the present invention on the cover plate 5 side as shown in FIG. 1, and the incident light passes through the anti-reflection film 5, the cover plate 3 and the substrate glass 2 as shown by the arrow, and the hologram element 1a And the element 1a
Is diffracted by the interference fringes. Then, the diffracted light follows the reverse path as the reproduction light and exits.

The hologram shown in FIG. 1 is used as a head-up display for an automobile as shown in FIGS. 3 and 4, and its structure will be described.
An incandescent lamp 8, a liquid crystal panel 9 disposed in front of the incandescent lamp 8, a reflecting mirror 10, and a hologram 1 are mounted on 3. The functions of the liquid crystal panel 9 display information such as speed, master warning, direction instruction, and map. In addition, the display 13 generally has the instrument panel 1.
It is installed near 5.

The light emitted from the incandescent lamp 8 is
And is reflected by the reflecting mirror 10 and enters the surface of the hologram 1. The hologram element 1a of the hologram 1 (FIG. 1)
The reflected reproduction light is reflected by the vapor-deposited film 11 deposited on the windshield 12 of the automobile, and the driver can visually recognize the display image 14 as a virtual image displayed at a distance. The display image 14 is displayed on the liquid crystal panel 9.

A hologram having the structure shown in FIG. 8 may be used instead of the structure shown in FIG. The hologram of FIG. 8 will be described. In this example, the dimensions of the substrate glass 2 are set to be smaller by the seal width of the sealant 7.

A hologram having the structure shown in FIG. 9 may be used instead of the hologram shown in FIG. The hologram shown in FIG. 9 will be described. In this example, the antireflection film 5 is formed directly on the other surface side of the substrate without providing the cover plate 3. With such a configuration, a miniaturized hologram having a small thickness can be obtained.

Further, a hologram having the structure shown in FIG. 10 may be used instead of FIG. The hologram of FIG. 10 will be described. In this example, the scattering prevention layer 6 may be formed on the surface of the cover plate 4 on which the hologram element 1a is provided, opposite to the surface on which the hologram element 1a is formed.

The hologram of FIG. 1 can be manufactured, for example, by the method shown in FIG. First, as shown in FIG. 5, dichromated gelatin (DCG) as a photosensitizer
Is formed on the surface of the substrate glass 2 with a film thickness of 10 μm to 40 μm, and after gelation or drying, it is stabilized in an atmosphere of about 20 ° C. and about 50 RH%. After that, a concave lens as a magnifying glass is recorded on the photosensitive material, and after development and drying, the substrate glass 2 provided with the hologram element 1a is sandwiched between the cover plates 3 and 4 by the sealant 7 as shown in FIG. , Fix.

Here, the recording of the subject on the photosensitive agent is generally performed by moving the substrate glass 2 provided with the photosensitive agent onto a lens 16 having a certain focal length and a prism 1 as shown in FIG.
7 and a silicone oil 15 as a refraction adjusting liquid.

Argon laser light having a wavelength of 514.5 nm is incident as incident light from the prism 17 side. After the incidence, since the refractive index is uniform, the laser beam linearly advances to the lens 16 side, and the reflected light reflected by the reflective film 18 formed on the surface of the copying lens 16 on the atmosphere side passes the photosensitive agent. When the light passes through, the light directly radiates from the laser light and is reflected by the lens 16 before interfering with each other to form interference fringes in the photosensitive agent.

A part of the light reflected by the lens 16 is not reflected by the substrate glass 2 but passes through the substrate glass 2 by the refractive index adjusting liquid 15 and is incident on the prism 17, and is partially reflected on the incident surface of the prism 17. . In this case, as shown in FIG. 5, the angle α of the incident surface of the prism 17 (30 ° in Example 1 described later) is adjusted with respect to the incident light, and the reflected light of the incident surface of the prism 4 is directed toward the photosensitive agent 1a. Do not proceed to. By disposing such a prism 4, it is possible to remove display noise due to reflected light at the interface that causes noise. By applying a black coating for absorbing light on the side surface of the prism 17, the reflected light on the incident surface of the prism 17 can be prevented from traveling in the direction of the photosensitive agent 1a.

With such a configuration, on one surface of the substrate 2 holding the hologram element 1a, on the other surface of the substrate 2 via the refractive index adjusting liquid 15,
Is provided, when the light reflected by the prism 16 is incident on the substrate 1 and is emitted again, a part of the light is not reflected on the other surface of the substrate 1. Since all the light can be made incident on the prism 17, a noise image is not recorded at the time of copying and recording the lens 16 with respect to the photosensitive material 1a.

Example 1 A substrate glass (made of soda glass, having a refractive index of about 1.52) of 112 mm × 46 mm × 1.8 mm and a thickness of 25 μm
To form a dichromated gelatin film as a photosensitive agent. The photosensitizer was added to 100 ml of a 4% gelatin solution in 0.6 ml.
g of ammonium bichromate dissolved therein and has a refractive index of about 1.55. The substrate glass to which the photosensitive agent was applied was left for 72 hours in a drier maintained at 20 ° C. and 50% RH. Thereafter, the wavelength 51 shown in FIG.
A 4.5 nm argon laser beam is reproduced (at an incident angle of 3).
(At 3.5) The incident angle was changed so as to be two colors of 540 nm and 600 nm, and the photosensitive agent was exposed to a total of 500 mJ of laser power. Note that the focal length of the lens 16 in FIG. 5 was 1000 mm.

After exposure, the substrate glass is washed with water until the color is removed, and a commercially available photographic hardening solution (Rapid® from Kodak) is used.
Fixer) for 10 minutes. After the water washing treatment, it was immersed in a 90% isopalanol solution for 10 minutes and dried with hot air.
Thereafter, heat aging was performed at 150 ° C. for 4 hours so that the wavelength did not change in the actual vehicle environment.

Thereafter, the periphery of the hologram element 1a is removed so that the seal width in FIG. 4 is 5 mm. MgF ₂ and T
A cover plate (112 mm × 46 mm × 1.0 mm) having a configuration in which four layers of iO ₂ were alternately laminated and having an antireflection film having a luminous reflectance of 0.3% formed on the surface was prepared.
On the other hand, a cover plate (1) having a 10 μm thick anti-scattering film formed on the surface by adding and mixing 5% of a black pigment (Glasslight 500 made by Cashew) to an epoxy resin.
12 mm x 46 mm x 1.0 mm). Epoxy thermosetting resin (trade name: CS-23, manufactured by Cemedine Co., Ltd.)
A sealing agent having a refractive index of 1.55, which is formed by 40-5), was applied to the surfaces of the two cover plates so as to have a thickness of 50 μm. The two cover plates were arranged on the substrate glass as shown in FIG. 1, and the substrate glass was sandwiched between the two cover plates via a sealant.

The above luminous reflectance was determined by the following equation.

[0036]

(Equation 1) Y% is the luminous reflectance, λ is the wavelength of light (10 mm steps),
S (λ) = 1 (flat light source), R (λ) is a spectral reflection spectrum, and y (λ) is col-or mat of 1931 CIE.
Indicate a ching function.

Example 2 Example 2 was the same as Example 1 except that the recording of the subject on the photosensitive agent was carried out by the method shown in FIG.

Here, the method of FIG. 11 will be described. In FIG. 11, an anti-reflection film 5 is formed on the surface of the substrate glass 2 opposite to the side where the hologram element 1a is provided, and a concave concave lens 16 for copying is formed on the hologram element 1a side via silicon oil as a refractive index adjusting liquid. And the incident angle θ of the argon laser beam is selected from two angles of 20 ° and 39 °, and is made incident.

Example 3 Example 3 was the same as Example 1 except that no antireflection film was formed. Example 4 Example 4 was the same as Example 1 except that the anti-scattering film was not formed.

Example 5 Example 5 was the same as Example 1 except that a sealing agent made of an epoxy-based thermosetting resin having a refractive index of 1.41 was used.

For the above Examples 1 to 5, the normal image luminance of 3000 cd / m ^{2 was obtained with} the head-up display configuration of FIG.
Measure the brightness of the noise image when
) And the noise ratio (see below). The noise image luminance was measured at the point having the highest luminance other than the normal image.
The hologram characteristics at this time were as shown in FIG.

[0042]

(Equation 2) From the above results, as shown in FIG. 7, in Example 1, the noise ratio was small and the displayed image was clear. Thus, it can be understood that the hologram of Example 1 has extremely low noise both at the time of reproduction and at the time of recording. Also, with respect to environmental resistance, by setting the seal width to 5 mm, it is possible to maintain the temperature at 65 ° C. and 9 ° C.
The hologram element did not disappear even after being left for 1000 hours in an atmosphere of 5% RH.

[Brief description of the drawings]

FIG. 1 is a sectional view of a hologram.

FIG. 2 is a plan view of FIG.

FIG. 3 is a schematic diagram showing a schematic configuration of a head-up display.

FIG. 4 is a schematic diagram showing a vehicle-mounted layout of FIG. 3;

FIG. 5 is a cross-sectional view illustrating a method of manufacturing a hologram.

FIG. 6 is a graph showing hologram characteristics in an example.

FIG. 7 is a graph showing a noise rate in the example.

FIG. 8 is a sectional view showing another example of the hologram.

FIG. 9 is a sectional view showing another example of the hologram.

FIG. 10 is a sectional view showing another example of the hologram.

FIG. 11 is a cross-sectional view illustrating a method of manufacturing a hologram as a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hologram 2 Substrate glass 3 Cover plate 4 Cover plate 5 Antireflection film 6 Scattering absorption film 7 Sealant

────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Yasuhiro Mizutani 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Inside Denso Co., Ltd. (72) Inventor Tetsuya Kato 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Nihon Denso Co., Ltd. (56) References JP-A-3-223807 (JP, A) JP-A-5-60912 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 5/32 G03H 1 / 00-1/30

Claims (13)

(57) [Claims] 1. A first member having one surface and the other surface facing each other and being optically transparent; and an interference fringe applied to the one surface of the first member as a recording medium. A hologram element on which the hologram element is formed and one of the first members on which the hologram element is formed
One surface and the other are provided on the surface side of
A second member having a surface of the second member, and the second member is connected to one surface of the second member and the atmosphere.
From the other surface side of the first member at the boundary surface of
A machine that absorbs light that enters and passes through the hologram element
A hologram comprising a scattering prevention film having a function . Wherein said scattering prevention film, by adding a desired pigment in the synthetic resin binder, the hologram according to claim 1, wherein the light is obtained by a resorbable membrane. 3. The hologram element is interposed between the first member and the second member, and the first member and the second member are separated by a sealant.
The hologram according to claim 1, wherein the hologram is bonded. Wherein said sealant is a hologram according to claim 3, characterized in that of at least one UV-curable organic resin or thermosetting organic resin. 5. a facing one surface and the other surface to each other, and the first member optically transparent, is applied to the one surface of the first member, the interference fringes as a recording medium A hologram element on which the hologram element is formed and one of the first members on which the hologram element is formed
One surface and the other are provided on the surface side of
A second member having a surface of the first member, the first member being provided on the other surface side of the first member, and entering from the other surface side of the first member.
An anti-reflection film having a function of preventing reflection of emitted light, wherein the second member is connected to one surface of the second member and the atmosphere.
In the interface, from the other surface side of the front Symbol first member
A machine that absorbs light that enters and passes through the hologram element
A hologram comprising a scattering prevention film having a function . Wherein said anti-reflection film, MgF _2, TiO _2,
Hologram according to claim 5, characterized in that comprises at least one of ZrO ₂ and SiO. 7. The first member and the second member,
6. The hologram according to claim 5 , wherein the hologram is adhered by a sealant. Wherein said sealant is a hologram according to claim 7, characterized in that of at least one UV-curable organic resin or thermosetting organic resin. 9. A first member having one surface and the other surface facing each other and being optically transparent, and an interference fringe applied to the one surface of the first member as a recording medium A hologram element on which the hologram element is formed and one of the first members on which the hologram element is formed
One surface and the other are provided on the surface side of
A second member having a surface , and one surface facing the other surface of the first member
And one surface and the other facing each other
And a third member having a surface of the second member, wherein the second member is connected to one surface of the second member by air.
At the boundary surface with the other surface of the first member.
And absorbs light transmitted through the hologram element.
A scattering prevention film having a function, wherein the third member is provided on the other surface of the third member.
Incident from the other surface side of the third member.
Having an antireflection layer having a function of preventing reflection of reflected light
Hologram characterized by. Wherein said said first member the second member and the first member and the third member, the sealant, the hologram according to claim 9, characterized in that is bonded . 11. The hologram according to claim 10 , wherein said sealant is made of at least one of an ultraviolet curable organic resin and a thermosetting organic resin. 12. The method of claim 11, wherein the interference fringes also claim 1, characterized in that it is constituted by two interference fringes having different pitches
Is the hologram according to any one of 5 or 9 . Wherein said anti-reflection film is also claim 1, characterized in that provided after the hologram element is exposed
Is the hologram according to any one of 5 or 9 .