JPH03255489A - Display device using hologram - Google Patents

Abstract

PURPOSE:To save space by recording the reproduction angle of a hologram at a whole reflection angle and making reproduced light incident at the whole reflection angle to reproduce a display image by using an optical system, such as prism, at the time of reproduction. CONSTITUTION:The hologram 25 recorded with the image desired to be reproduced is mounted on the lower side part of a meter panel 21 in the state of registering the display surface thereof on the display surface of the meter panel 21. The prism 27 is adhered and fixed by using a colorless and transparent adhesive 26 to the rear surface of this hologram 25. A reproduced light source 28 is installed on the rear surface side of this meter panel 21 and the reproduced light generated by this reproduced light source 28 is cast via the prism 27 to the surface of the hologram 25 at the whole reflection angle so that the reproduced image is observed by the driver's eyes 29. Namely, the reproduced light source is set in the rear surface part of the hologram 25 and, therefore, there is no need for installing special equipment in front of the hologram. The setting of the required space to a min. is possible in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a display device using a hologram, which is installed, for example, in the driver's seat of an automobile, and displays various information other than a normal speedometer, for example.

[Prior Art] Various display devices using holograms have been developed and proposed.
As shown in Japanese Utility Model Publication No. 86 and furthermore, Japanese Utility Model Publication No. 62-73266, white reproduction light is irradiated from in front of the hologram, thereby reproducing a three-dimensional image. In this case, a mask plate is provided to prevent white light, which is reproduction light, from entering the observer's eyes.

However, with this configuration, a space is required for the distance between the hologram and the reproduction light source, as well as a space for the reproduction light source and the mask plate. This is especially true when it is difficult to secure space in front of the hologram. This makes it difficult to realize display devices with various configurations.

Furthermore, since the reproduction light source is placed in front of the hologram, if there is dust or the like, this dust will block the reproduction light source, causing a portion of the reproduced image to disappear. In order to solve these problems, it is necessary to install a large front cover in front of the hologram.

There is a possibility that disturbance light enters such a hologram from the same direction as the reproduction light. For example, as shown in FIG. 11, when the reproduction source 12 is set on the front surface side of the hologram 11, disturbance light from the sun 13 and the like is further incident on the display surface side of the hologram 11. Therefore, along with the regular reproduced image A reproduced by the reproduction light from the reproduction source 12, a ghost image B due to the disturbance light is generated.

Further consideration of the display functions of automobiles and the like shows that there is a desire for display mechanisms such as meters to have multiple functions.

For example, one display area may display two or more types of display. However, since holograms have the characteristic that a ghost image appears due to disturbance light,
It is very difficult to display many types of display images in the same display area.

[Problems to be Solved by the Invention] The present invention has been made in view of the above points. In addition to reliably preventing the generation of ghost images due to ambient light such as the sun, it is possible to ensure that high-quality reproduction images are obtained, and it is also possible to display a wide variety of display images. The present invention aims to provide a display device using a hologram that makes it possible.

[Means for Solving the Problems] A display device using a hologram according to the present invention uses a hologram recorded with a reproduction angle set to a total reflection angle, and a reproduction light source is set on the back side of this hologram. At the same time, the reproduction light from this reproduction light source is made to enter the hologram at a total reflection angle via an optical system, and as the optical system, for example, a prism or a Fresnel hologram is used. Here, for example, a plurality of image information is recorded on the hologram, and a reproduction light source is set corresponding to each of the recorded images.

[Function] In a display device using a hologram configured in this way, the reproduction light source is set at the back of the hologram, so there is no need to install special equipment in front of the hologram. Furthermore, even if there is optical obstruction such as dust in front of the hologram, it will not affect the reproduced image. Furthermore, no disturbance light is incident from the same direction as the reproduction light. Therefore, light from the sun or the like outside the display device is not incident on the hologram and no ghost image is generated, and a reproduced image of high quality can be reliably obtained. In other words, it can be used in places with limited space, such as the meter panel of a car, without considering ambient light.
A display device using this hologram can be installed. Further, when a plurality of image information is recorded on the hologram, each recorded image is reproduced by a correspondingly set reproduction light source, so that a plurality of images can be reproduced in the same display area.

[Embodiments of the invention] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows its configuration, and this embodiment shows an example in which a hologram display device is installed in the meter panel of an automobile. A meter panel 21 for displaying vehicle speed, for example, is set on the dash board 20 section. This meter panel 21 is set to face a driver's seat (not shown), and a pointer 22 and a needle 23 are attached to this meter panel 21, and a cover 24 is appropriately provided on the display surface side. .

The hologram 25, which has recorded the image you want to reproduce in advance,
It is attached to a part of the meter panel 21, for example, the lower side, with its display surface aligned with the display surface of the meter panel 21. A prism 27 made of glass, resin, or the like is adhesively fixed to the back surface of the hologram 25 using a colorless and transparent adhesive 26. This meter panel 21
A reproducing light source 28 is installed on the back side of the reproducing light source 2.
The reproduction light generated in step 8 is made to strike the surface of the hologram 25 at a total reflection angle via the prism 27.

The image reproduced by this hologram 25 is then observed by the driver's eyes 29.

FIG. 2 is an enlarged view of the automobile display device shown in FIG. 1, particularly the hologram display device portion, and the same components as in FIG. 2 are designated by the same reference numerals.

Here, the reproduction light from the reproduction light source 28 may be directly incident on the prism 27 and incident on the hologram 25 at a total reflection angle, but the reproduction light may be incident on the meter panel 25.
In order to efficiently utilize the limited volume of the back surface of the prism 27, it is effective to use a reflecting mirror 30 as appropriate and to reflect the reproduced light from the reproduced light source 28 with the reflecting mirror 30 and guide it to the prism 27. be.

There are two types of holograms: reflection-type and transmission-type holograms.

Among these holograms, there is a white light reproduction reflection hologram (
The Lippmann hologram) obtains a reconstructed image by irradiating reproduction light from in front of the hologram surface.To reproduce meter images and other display images using this type of hologram, Japanese Utility Model Publication No. 62-74266 As shown in , a configuration is adopted in which a reproduction light source is placed in front of the hologram.

In the hologram 25 shown in FIGS. 1 and 2, in consideration of these points, the conditions for total reflection of the reproduction light within the gelatin, glass, or resin (substrate of the hologram dry plate) constituting the hologram are set. To record and produce image information to be displayed satisfactorily. Then, as shown in FIG. 2, the prism 27 is glued with a colorless and transparent adhesive 2B.
is used to adhere to the back surface of the hologram 25, and the reproduction light from a reproduction light source 28 composed of a halogen lamp, a tungsten lamp, etc. is reflected by a reflecting mirror 30 and made to enter the prism 27.

The playback destination that enters the prism 27 is a transparent adhesive 26
, and the emulsion 251 of the hologram 25 (on which interference fringes are recorded), is totally reflected at the interface between the substrate 252 of the hologram 25 and air, and returns to the emulsion 251.

At this time, visible light incident on the emulsion 251 is not diffracted by the hologram 25. However, the light that has been totally reflected and returned to the emulsion 251 is incident on the surface of this emulsion 251 at the reproduction angle;
Of the light incident on one surface, only light of a certain wavelength is diffracted, and the observer (driver) can observe the reproduced image 31.

That is, by configuring in this way, it is possible to arrange the reproduction light source 28 behind the hologram 25, and there is no need to take up a space for the reproduction light source in front of the hologram 25, which inevitably improves the design etc. Freedom is expanded.

Furthermore, as explained using FIG. 11, in the configuration in which the reproduction light source is placed in front of the hologram, when disturbance light such as sunlight is incident, the normal reproduction image reproduced by the reproduction light source is Additionally, ghost images occur.

However, in the apparatus shown in the embodiment, as shown in FIG. 3, the hologram 25 is configured so that the reproduction angle is set at the total reflection angle, so the disturbance light is basically transmitted inside the hologram substrate 252. , the angle of total reflection is not reached, and therefore no ghost image is reproduced.

FIG. 4 shows an optical system for producing a hologram 25 in which the reproduction angle is set to the total reflection angle, and the prism 4
A hologram dry plate 43 is set between 1 and 42, and a reference beam 44 made of convergent light is made incident thereon.

Further, reference numeral 45 denotes a master hologram, and a parallel object beam 46 is made incident on this master hologram 45. 47 is a real image formed by the master hologram 45; In this case, by selecting the incident direction of the reference light 44, the position of the reproduction light source 28 when constructing the hologram display device can be specified.

FIG. 5 shows another example of an optical system in which the reproduction light is incident on the hologram 25 at a total reflection angle, in which a Fresnel hologram 31 (transmission type hologram) is used instead of the prism of the previous embodiment. The hologram 31 is bonded to the back surface of the hologram 25 using a transparent adhesive or the like.

FIG. 6 shows an optical system for producing the Fresnel hologram 31 used in this example.

That is, the hologram dry plate 51 is set between the first and second prisms 52 and 53, and the first prism 52
from different planes of the first and second parallel beams 54 and 5
5 is made incident, and is made to intersect at the 51 part of the hologram dry plate. In other words, the holographic dry plate 51 is exposed to a human image 1.
The parallel light 54 is diffracted in the direction of emission of the second parallel light 55 (this is the angle of total reflection).

Therefore, by joining the Fresnel hologram 31 and the hologram 25 (Subman hologram) produced by such an optical system with an adhesive as shown in FIG. 5, the reproduced light from the reproduced light source can be suppressed. The incident light passes through the Fresnel hologram 31 and the hologram 25
The light is incident on the prism 27 at an angle of total reflection, and has the same effect as the prism 27 of the previous embodiment.

In the embodiments so far, examples have been shown in which one image is reproduced using a hologram. FIG. 7 shows a cross-sectional configuration of a hologram display device for reproducing two types of images, for example. The hologram 25 is bonded to a prism 61 made of a material that has the same or similar refractive index as the hologram 25 with a transparent adhesive 62 that has the same or similar refractive index. prism 6
A display device 63 such as anti-reflection coating or liquid crystal, electroluminescence, CRT, fluorescent display tube, etc. is set on the back of the device 1, and the observer's eyes 29 usually see a hologram 25, adhesive 62, and a prism. 61 so that the color of the anti-reflection coating or information from the product display 63 can be observed.

With respect to the prism B1 set in this way, for example, two
Reproduction light sources 281 and 282 are set. In this case, the reproduction light sources 281 and 282 are arranged so that the reproduction light generated can be totally reflected on the surface of the glass substrate 252 of the hologram 25.

The emulsion 251 of the hologram 25 contains first image information that is reproduced by light that is totally reflected by the substrate 252 from the reproduction light source 281 due to interference fringes, and the reproduction light source 28
Second image information is recorded that is reproduced by the light that is totally reflected by the substrate 252, and the reproduced image 6 is reproduced by the reproduced light from these reproduction light sources 281 and 282.
4 and 65 are played back.

That is, the observer's eyes 29 can pass through the hologram 25 and the prism 6 (as described above) and observe the display 63 such as anti-reflection coating or liquid crystal.

Now, assume that the display 63 is coated with anti-reflection coating. When the reproduction light source 281 is turned on in this state, the reproduction image 64 is reproduced by the reproduction light from the reproduction light source 281 and can be observed. Furthermore, when the reproduction light source 282 is turned on, the reproduction image 65 is reproduced and displayed.

When the reproduction light sources 281 and 282 are turned on at the same time, the reproduction images 64 and 65 are observed simultaneously.

Furthermore, if a display device 63 made of liquid crystal or the like is installed on the back surface of the prism 61 instead of anti-reflection coating, the reproduced images 64 and 65 by the hologram 25 can be observed at the same time as the image displayed by the display device 63.

In this case, if the display images or display colors of the reproduced images 64 and 65 are set differently, the reproduced light sources 281 and 2
82 simultaneously, a completely new display image can be expressed.

That is, by configuring in this manner, a multiplex display device is realized which has the feature that a hologram reconstructed image is not reproduced by external light such as sunlight or fluorescent lamp light. Furthermore, it is possible to configure a combination of a display device using liquid crystal or the like and a hologram display device.

In this embodiment, a prism 61 is used in combination with the hologram 25, but as shown in FIG.
The reproduced light from each of holograms 1 and 282 is
It is also possible to use a plate glass 66 whose end face is polished so that the light is totally reflected by the glass substrate 252 of No. 5. In this figure, the same components as in FIG. 7 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

FIGS. 9 and 10 show still another embodiment, with FIG. 9 showing the configuration seen from the side and FIG. 10 showing the configuration seen from the front. That is, in this embodiment, a hexagonal prism 70, for example, is bonded to the hologram 25.

Then, reproduction light sources 281 to 286 are installed corresponding to each of the six surfaces around this prism 70. In this case, so that the reproduced image is not reproduced by the reproduction light from the adjacent reproduction light source, for example, the image to be reproduced by the reproduction light source 282 is prevented from being reproduced by the light from the reproduction light source 281.
The direction angle of the reproduction light from the reproduction light sources 281 to 28B is α(-2
5°) or more.

That is, according to this hologram display device, six reconstructed images can be observed selectively and simultaneously.

[Effects of the Invention] As described above, in the display device using the hologram according to the present invention, the reproduction angle of the hologram is recorded at the total reflection angle, and the reproduction light is recorded using an optical system such as a prism during reproduction. A display image is reproduced by making the light incident at an angle of total reflection.

Therefore, there is no need to install a reproduction light source in front of the hologram, and a display device can be configured by placing the reproduction light source behind the hologram, increasing the degree of freedom in design and saving space. I can do it. Furthermore, ghost images caused by disturbance light from in front of the hologram can be removed outside the viewing range. Therefore, it is easy to incorporate and set it into, for example, an automobile meter panel, and in this case, visibility from the driver can be reliably obtained. Further, by setting a plurality of reproduction light sources, a plurality of reproduction images can be selectively observed, and a plurality of images can be observed simultaneously, and displays such as liquid crystals can be easily used in combination, for example.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional configuration diagram for explaining a display device using a hologram according to an embodiment of the present invention, FIG. 2 is an enlarged view of the main parts of the display device, and FIG. FIG. 4 is a diagram illustrating the state of incident light in the display device, FIG. 4 is a diagram showing an optical system for producing a hologram used in the display device, and FIG. 5 is a cross-sectional configuration explaining a second embodiment of the present invention. Figures 6 and 6 are diagrams showing the optical system for producing the Fresnel hologram used in this example, Figures 7 and 8.
The figures are cross-sectional configuration diagrams illustrating third and fourth embodiments of the present invention, FIG. 9 is a side view of a display device according to a fifth embodiment, and FIG. 10 is a display device shown in FIG. 9. FIG. 11 is a side view showing how a ghost image is generated in a conventional hologram display device. 21... Meter panel, 25... Hologram, 26
... Adhesive (transparent), 27.61 ... Prism, 2
8.281.282... Reproducing light source, 30... Reflecting mirror, 31... Fresnel hologram, 66... Plate glass.

Claims (6)

[Claims] (1) A hologram in which the reproduction angle of image information is recorded at a total reflection angle, a reproduction light source located on the back side opposite to the display surface side of this hologram, and reproduction light from this reproduction light source, A display device using a hologram, comprising: an optical system installed opposite to the back surface of the hologram to make the light incident on the hologram at a total reflection angle. (2) A display device using a hologram according to claim 1, wherein the optical system is constituted by a prism adhesively set on the back side of the hologram. (3) The display device using a hologram according to claim 1, wherein the optical system is constituted by a Fresnel hologram adhesively set on the back surface of the hologram. (4) At least two pieces of image information are recorded on the hologram at different playback angles, and a plurality of playback light sources are set corresponding to the playback angles of the image information. A display device using the hologram of No. 1. (5) The reproduced light from each of the plurality of reproduction light sources is incident on the hologram through an optical system that makes the light incident on the hologram at a total reflection angle, and this optical system is coated with anti-reflection coating. A display device using a hologram. (6) The reproduction light from each of the plurality of reproduction light sources is incident on the hologram through an optical system that makes the light incident on the hologram at a total reflection angle, and a liquid crystal display is installed in this optical system. A display device using a hologram.