JPH10244789A - Hologram memory card and its record reading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hologram memory card capable of preventing the deterioration of a hologram recording medium due to outdoor light, and also provide a record reading device thereof. SOLUTION: A hologram memory card is formed by laminating a hologram recording material layer 3 and liquid crystal shutters 4-6 operated electrically and provided on the layer from the side of a card base 1, and in the state of not applying the normal voltage, a liquid crystal layer 5 between a first polarization filter layer 4 and a second polarization filter layer 6 is provided with optical activities of 90 deg.C, and the light from outdoor is cut and shut off to avoid the deterioration of the hologram recording material layer 3. The voltage is applied from the outside to the liquid crystal layer 5 to open the liquid crystal shutters 4-6, and the recording of a hologram can be recorded on the hologram recording material layer 3 and also can be read therefrom.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hologram memory card and a recording / reading apparatus therefor, and more particularly to a hologram memory card capable of preventing deterioration of a hologram recording medium and a recording / reading apparatus therefor.

[0002]

2. Description of the Related Art Recently, an ID card used as an authentication record type information carrier has been changed from a conventional magnetic card to an IC card or an optical card capable of encrypting and recording information and having a large capacity memory function. It is getting.

[0003] The main reasons for this are that IC cards and optical cards have high information recording security and a large amount of data to be recorded. For example, personal information, such as information on buying and selling, money in hand, communication, This is because the ID number such as a utility bill and a car license, and medical information and the like can be digitally recorded and registered and possessed, thereby providing more uses because of its versatility.

[0004]

However, such an IC
Due to the technological advancement of cards and optical cards, the total storage capacity is at most only about 2 to 10 megabytes. For example, when recording images, digital data with a limited number of pixels, no matter how compressed , And the number of images that can be stored is also limited. Therefore, for example, it has not been possible to record a moving image, register a high-definition image, or register a three-dimensional image.

On the other hand, holograms have been studied for use as large-capacity memory media since the beginning of their development. However, the use of a photosensitive film has significantly deteriorated the light, and at present stable recording has been achieved. Not used as a medium.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a hologram memory card capable of preventing deterioration of a hologram recording medium due to external light and a recording / reading apparatus therefor. It is.

[0007]

A hologram memory card according to the present invention that achieves the above object has the following features.
At least a hologram recording material layer and an electrically operated liquid crystal shutter provided thereon are laminated.

In this case, the liquid crystal shutter is composed of a first polarizing filter layer, a liquid crystal layer, and a second polarizing filter layer from the card substrate side, a guest / host liquid crystal layer, or a polymer dispersed liquid crystal. There are layers and the like.

The liquid crystal shutter is closed in a normal state in which no voltage is applied to protect the hologram recording material layer, and the liquid crystal shutter is opened by applying a voltage from the outside to open the hologram recording material. The hologram can be recorded on or read from the layer.

In another hologram memory card of the present invention, at least a hologram recording material layer and an electrically operated electrochromic shutter provided thereon are laminated from the card substrate side. It is characterized by the following.

In the above, it is desirable that the hologram recorded in the hologram recording material layer is a hologram obtained by subjecting object information to optical Fourier transform. In this case, the object information includes two-dimensional analog information and two-dimensional digital information.

Further, the hologram recording material layer may be provided in a part of the plane area of the card base material, and the other area may function as a structural support of the card base material.

Further, characters and images are printed on the area where the hologram recording material layer is not provided, and the area where the hologram recording material layer is provided is coated with ink that transmits light of the hologram recording / reading wavelength. Characters and images may be printed.

The recording of the hologram on the hologram recording material layer or the reading of the hologram can also be performed by light in the infrared (wavelength: 700 nm to 2000 nm) or ultraviolet (wavelength: 200 nm to 400 nm) region.

According to the recording / reading apparatus for a hologram memory card of the present invention, a hologram is recorded on a hologram recording material layer in a state where a voltage is externally applied to the hologram memory card and the shutter is opened. Alternatively, the hologram recorded on the hologram recording material layer is read.

In the present invention, since at least a hologram recording material layer and an electrically operated liquid crystal shutter provided thereon are laminated from the card substrate side, the hologram recording or hologram recording or recording is performed. Since it is only necessary to apply a voltage and open the shutter only at the time of reading, deterioration of the hologram recording medium due to light can be prevented. In addition, in a normal state, it is difficult to read information recorded on the hologram, so that the recorded information is easily concealed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the hologram card of the present invention and a recording and reading apparatus for the same will be described below. FIG.
1 is a perspective view of a memory card including a hologram recording area according to the present invention. A memory card 10 has a print recording area 11 and a hologram recording area 12 on its surface. As will be described later, printing may be performed on the surface of the hologram recording area 12, but it is necessary that the printing ink has characteristics that do not hinder recording and reproduction of the hologram recording area 12.

FIG. 2 is a cross-sectional view of the hologram recording area 12, in which, from the bottom, a hologram recording of a substrate 1, an electrode layer 2, a silver salt sensitizer, a gelatin dichromate, a photopolymer, etc. Material layer 3, first polarizing filter layer 4, TN liquid crystal layer 5, second polarizing filter layer 6,
It comprises a transparent protective layer 7 and a printing layer 8, and the first polarizing filter layer 4 and the second polarizing filter layer 6 are arranged such that their transmission axes are parallel to each other. Note that an alignment layer (not shown) is disposed between the first polarization filter layer 4 and the TN liquid crystal layer 5 and between the TN liquid crystal layer 5 and the second polarization filter layer 6.
The printing ink of the printing layer 8 has a color that transmits (does not impede or absorb) a wavelength used for recording or reproducing a hologram on the hologram recording material layer 3.

Since the hologram recording area 12 has the above-described configuration, the first hologram recording area 12 does not have the first voltage when no normal voltage is applied.
Since the liquid crystal layer 5 between the polarizing filter layer 4 and the second polarizing filter layer 6 has an optical rotation of 90 °, light from the outside becomes linear polarized light in a predetermined direction in the second polarizing filter layer 6. , The TN liquid crystal layer 5 converts the light into linearly polarized light in a direction perpendicular to the direction, and the first polarization filter layer 4 blocks the light. Therefore, the external light which deteriorates the hologram recording material layer 3 is cut off, and the deterioration of the hologram recording material layer 3 can be avoided.

Now, in order to record predetermined information on the hologram recording material layer 3 of such a memory card 10 as a hologram or to read the hologram recorded on the hologram recording material layer 3, as shown in FIG. Transparent substrate 2
1 is provided with an electrode plate 20 having a transparent electrode layer 22 made of ITO or the like provided thereon.
A predetermined voltage V is applied between the electrode layer 2 of the memory card 10 and the transparent electrode layer 22 of the electrode plate 20 by pressing the transparent electrode layer 22 so that the transparent electrode layer 22 is in close contact therewith. In this state,
Since the optical rotation of the TN liquid crystal layer 5 is lost, the light from the outside becomes linearly polarized light in a predetermined direction in the second polarization filter layer 6, and no rotation of the polarization plane occurs in the liquid crystal layer 5; 6 can pass through the first polarizing filter layer 4 in which the transmission axis is arranged in parallel.

Therefore, when recording a hologram, a voltage V is applied to a liquid crystal shutter composed of the two polarizing filter layers 4 and 6 and the liquid crystal layer 5 sandwiched between the layers to open the hologram and make it transparent. Alternatively, recording can be performed by causing the object beam 24 and the reference beam 23 to enter the same region of the hologram recording material layer 3 at mutually different incident angles and causing them to interfere with each other.
In order to read the hologram recorded on the hologram recording material layer 3, when reading light (reproduction illumination light) is incident on the same optical path as the reference light 23 in FIG. 3, reproduction proceeds in the direction opposite to the arrow of the object light 24. Since the light is diffracted, a one-dimensional or two-dimensional photoelectric conversion element such as a CCD is arranged at the position of an object 26 such as a spatial modulator for information display arranged in the optical path at the time of recording, and the reproduced light is reproduced. Can be read by photoelectrically converting the recording information contained in the.

By the way, in the above configuration, the electrode layer 2
Is formed of a transparent electrode material such as ITO, and is formed between the hologram recording material layer 3 and the first polarization filter layer 4 or the first
It may be arranged between the polarizing filter layer 4 and the liquid crystal layer 5.

When a guest-host liquid crystal or a polymer-dispersed liquid crystal is used instead of the TN liquid crystal, the polarizing filter layers 4 and 5 can be omitted.

Further, instead of the liquid crystal shutter, an electrochromic material layer which becomes colored when a current flows in a predetermined direction and becomes transparent when a current flows in the opposite direction can be used.

In the structure shown in FIG. 2, the electrode layer 5 may be omitted. In this case, in order to open the liquid crystal shutter, as shown in FIG.
Another electrode plate 27 is brought into close contact with the back surface side,
If the voltage V is applied between 27, the liquid crystal shutter 9 on the hologram recording material layer 3 can be opened to make it transparent.

Incidentally, in recording a hologram on the hologram recording material layer 3, it is desirable that the object information is Fourier-transformed and recorded as a compressed image. For that purpose, for example, as shown in FIG. 3, the object light 24 may be Fourier-transformed by the convex lens 25. In the arrangement of FIG. 3, the object 26 is arranged immediately after the convex lens 25, but immediately before that, or
The object 26 may be arranged near the front focal plane.

When the information to be recorded is analog information such as image information, the information carrier is directly illuminated,
The scattered light may be Fourier-transformed by the convex lens 25 and recorded as a compressed image in a small area of the hologram recording material layer 3. Also, once displayed on a display such as a spatial modulator, the display light is Fourier transform may be performed and recorded in the same manner. On the other hand, voice information using a standardized sound source and standardized digital information such as characters and numbers are temporarily converted into two-dimensional digital information such as a two-dimensional barcode, and the two-dimensional digital information is converted. After displaying on a display such as a spatial modulator and performing Fourier transform and compression in the same manner as above,
Record.

Regarding reproduction and reading, analog information such as image information may be projected directly through a lens through reproduction light, or reproduced and digitally captured by a scanner or the like and reproduced as digital information. Good. The digital information once converted into two-dimensional digital information and recorded is obtained by digitally capturing a projected image of two-dimensional digital information such as a two-dimensional barcode by a scanner or the like, developing the binary image into a binary file, and reproducing the binary file.

In the present invention, since the two-dimensional analog information and the two-dimensional digital information as described above are all condensed and recorded by a convex lens, the recording density is extremely high. Therefore, the access time to the medium is only one irradiation of the light through the convex lens, and the decoding can be controlled electronically, so that the mechanical work is extremely small and the read / write time can be greatly reduced. Since it is not necessary to compress the image for each pixel of the analog information, the image information is not lost, and the digital processing and processing time required for compression and reproduction can be omitted. It has the feature that a recorded image can be reproduced even with a playback device.

Although the hologram memory card and the recording / reading apparatus of the present invention have been described based on the embodiments, the present invention is not limited to these embodiments, and various modifications are possible. For example, the hologram memory medium is not limited to a card shape but may be a disk shape. The hologram recording area may be provided on the entire surface of the card or on a part of the card. When it is provided in a partial area of the card, it is desirable to arrange the card at a position deviated from the center rather than the central part where the bending stress of the card is likely to be applied. Further, as the arrangement of the electrode layers, an example in which the electrode layer is provided below the liquid crystal layer and an example in which no electrode layer is provided have been described. However, the electrode layers may be disposed on both sides of the liquid crystal layer. Alternatively, relief holograms that are not easily degraded by external light may be arranged side by side in a partial area of the card and read by the same hologram reading device.

[0031]

As is apparent from the above description, it is only necessary to apply a voltage and open the shutter only when recording or reading a hologram, so that deterioration of the hologram recording medium due to light can be prevented. In addition, in a normal state, it is difficult to read information recorded on the hologram, so that the recorded information is easily concealed.

[Brief description of the drawings]

FIG. 1 is a perspective view of an example of a hologram memory card according to the present invention.

FIG. 2 is a sectional view of a hologram recording area of the hologram memory card of FIG.

FIG. 3 is a diagram showing an arrangement for recording and reading a hologram on a hologram recording material layer of a hologram memory card.

FIG. 4 is a diagram showing an arrangement for opening a liquid crystal shutter when no electrode layer is provided on the hologram memory card.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Card base material 2 ... Electrode layer 3 ... Hologram recording material layer 4 ... First polarizing filter layer 5 ... TN liquid crystal layer 6 ... Second polarizing filter layer 7 ... Transparent protective layer 8 ... Printing layer 9 ... Liquid crystal shutter 10 ... Hologram Memory card 11 Print recording area 12 Hologram recording area 20 Electrode plate 21 Transparent substrate 22 Transparent electrode layer 23 Reference light 24 Object light 25 Convex lens 26 Object 27 Electrode plate

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // G11B 7/00 G11B 7/00 A 7/24 572 7/24 572C

Claims (12)

[Claims] 1. A hologram memory card comprising at least a hologram recording material layer and an electrically operated liquid crystal shutter provided thereon laminated from a card base material side. 2. The hologram memory card according to claim 1, wherein the liquid crystal shutter comprises a first polarizing filter layer, a liquid crystal layer, and a second polarizing filter layer from the card substrate side. 3. The hologram memory card according to claim 1, wherein said liquid crystal shutter comprises a guest / host liquid crystal layer or a polymer dispersed liquid crystal layer. 4. The liquid crystal shutter is closed in a normal state in which no voltage is applied to protect the hologram recording material layer, and the liquid crystal shutter is opened by applying a voltage from the outside, so that the hologram recording is performed. 4. The hologram recording on the material layer is enabled or the hologram is readable.
A hologram memory card according to any one of the preceding claims. 5. A hologram memory card comprising at least a hologram recording material layer and an electrically operated electrochromic shutter provided thereon, laminated from the card substrate side. 6. The hologram memory card according to claim 1, wherein the hologram recorded on the hologram recording material layer is a hologram obtained by subjecting object information to optical Fourier transform. 7. The hologram memory card according to claim 6, wherein said object information is two-dimensional analog information. 8. The hologram memory card according to claim 6, wherein said object information is two-dimensional digital information. 9. The card material according to claim 1, wherein the hologram recording material layer is provided in a part of a plane area of the card base material, and the other area functions as a structural support of the card base material. A hologram memory card according to any one of the preceding claims. 10. A character / image or the like is printed in an area where the hologram recording material layer is not provided, and light of a hologram recording / reading wavelength is transmitted in an area where the hologram recording material layer is provided. The hologram memory card according to any one of claims 1 to 9, wherein characters, images, and the like are printed with ink. 11. The recording of a hologram on the hologram recording material layer or the reading of the hologram is performed by light in an infrared (wavelength: 700 to 2000 nm) or ultraviolet (wavelength: 200 to 400 nm) region. Item 11. The hologram memory card according to any one of items 1 to 10. 12. A hologram is recorded on the hologram recording material layer in a state where the shutter is opened by applying a voltage from the outside to the hologram memory card according to any one of claims 1 to 11. Alternatively, a recording and reading apparatus for a hologram memory card, which reads a hologram recorded on the hologram recording material layer.