JPS63500747A - Reproduction of optical data storage media - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Reproduction of optical data storage media The present invention relates to the reproduction of optically readable data storage media.

The optically readable data storage medium may be magnetic tape or disk or conventional The fact that it has theoretical advantages over other methods such as vinyl records It is well known. There are also other advantages in certain applications, such as resistance to wear and tear. However, the main advantage of optical approaches is that higher storage densities can be obtained. At present Despite the theoretical advantages of optical data storage, practical difficulties and limitations Optical methods are prevented from replacing existing methods in many fields.

One area where optical methods have been commercially successful is in the so-called compact disc. There is. This is an alternative to traditional vinyl records, but they read just like vinyl records. It's just something you take away. A compact disc is usually a record that is modulated onto a photosensitive material. Pressing or injection molding in mass production to reproduce the master created by the action of a laser beam It is in the shape of a disc of plastic material formed by. plastic disk metallization, and then the change in reflectance is detected by a reader for initial modulation. The information contained within the generated laser beam can be reshaped.

The present invention saves complex manufacturing processes that can be produced economically when a large number of boards are required. This is a step-by-step simplification. For this reason, a computer's read-only memory (RO) M) is also being evaluated, and a so-called CD-ROM has also been proposed, but the The production of compact discs is mainly concentrated in the recording industry.

There are two other categories of applications for optical data storage, which include video display. discs and digital optical discs. However, this is an evolving field. However, the difference between the two categories is not clear.

Videodiscs are manufactured by many companies, and technically they are generally compact and Similar to a disc, the information content is video rather than audio. Ru. The points mentioned above regarding compact disc manufacturing cost 1~ are video discs. The same applies to. That technique is still read-only; read and replay Due to the competition with video tape recorders, which can be used for both Deodecs have been commercially successful only in areas where they offer special advantages. This way One such area is the provision of educational or training material, where interaction It is particularly effective to be able to act in a similar manner. Another area is electronic publishing, which In this case, high storage density is valuable and the read-only rule is not important. both In this area, the cost disadvantages associated with low-volume production make this method difficult to apply. This could be a limiting factor. Many other applications where small quantities of reproduction are required are due to economic factors. Therefore, it is completely excluded from consideration.

Digital optical discs have been proposed by many companies, and currently there are quite a number of Research and development is being carried out. Except for very limited uses where read-only operation is sufficient. As such, it is necessary to allow users to write information to the disk. About this Two approaches have been developed, of which "one-time write" optical discs When a user writes information to a blank disk, the information cannot be changed after that. In contrast, "erasable-rewritable" discs can be rewritten many times. It is something that can be done.

Concerning "one-time writing" optical discs and "erasing/reversing" optical discs A number of drawbacks have arisen with the various proposals.

In actual use, by repeating the writing operation, at least one of the master discs can be , preferably having multiple backup copies. this will waste your computer's time. The designs that have been proposed so far The structure of the disk is relatively expensive, and the need for backup often reduces the operational history of the system. Expenses may increase considerably. This increase is clearly a one-time, non-reusable Very clear about backup by writing. Erasure - rewordable di disks are more expensive, and although backup copies can be reused, Significant additional costs arise from the need to maintain an increasing inventory of inventory.

In the development of new disk technology, high storage density and durability sometimes go hand in hand. It becomes a wish. In other words, the technology capable of very high storage densities is It would be impractical because it would be unbearable. As a result, the allowable storage density is Even if available, some types of discs may require special handling precautions. Dew.

On the one hand, it is simple, relatively inexpensive, durable against breakage, and special in use. provides a method for duplicating data storage media that requires very few countermeasures; It is one object of the present invention.

Replicating data storage media that allows for high storage densities and has the advantages mentioned above. It is still another object of the present invention.

Any optically detectable tracking information recorded on the above media may be duplicated. It is a further object of the invention to provide a method for duplicating data storage media produced by Ru.

Holo is used in many cases where lasers are used to write information onto photosensitive materials. It has been previously recognized that graphical methods have many advantages. An example in this regard European Patent No. 9045, US Patent No. 3842197, British Patent No. 13512 Reference may be made to No. 02 and French Patent No. 2,217,760. These various In the proposal, the writing and reading processes are holologized so that the storage density is increased. Raffi is used. Furthermore, the recorded image may not be a binary code but may have scratches, foreign objects, or Interference fringe pattern that spreads over a large area compared to the size of the object that causes other misreadings It is resilient and error tolerant to damage caused by

The use of bolography thus enhances certain optical techniques. However, this very often results in a significant increase in costs. Also for reading There were considerable difficulties in referencing the data accumulated for this purpose.

French patent specification No. 2368780 is also noteworthy, but it is transparent and has a clear design. optical data storage medium in which data is encoded by changes in the phase of transmitted light Disclosed is a method for replicating . Irradiate the medium with coherent light to Due to interference between the light that normally passes through the medium in the side plane and the light that is diffracted at each sign. It has been proposed to form a striped pattern that results from This striped pattern is the photosensitive material The image is recorded on the image and becomes an interference photograph. This is not a statue that can be seen directly, but please be careful By separating the diffraction of each method, it is possible to re-form an image using an appropriate optical system.

This proposed method of recording is limited to certain types of optical data storage media. Applicable. For example, data storage media in which the code is identified by reflectance, e.g. In other words, it is used for disks in the category that is the majority of those currently in use. Can not. In general, conventional literature assumes that there is a device for creating normal interference photographs. ing. For example, when creating interference photographs or holograms, there is a gap between the object and the emulsion during the exposure time. (or the light used even if there is such a movement) It can be seen that it is necessary to cormorant. Because of this need, holograms have traditionally been virtually mounted and suspended against vibrations. The structure is created on an optical table which eliminates problematic vibrations. copy The data storage medium to be used has a rigid support layer (e.g. coated on glass) (in the case of photographic emulsions), it is small but cannot be ignored compared to the wavelength. Stresses and creep in the medium of large magnitude can destroy interferograms. Toga. This method cannot be used, for example, for photosensitive materials with thin plastic support layers. Not possible.

Data storage such as a storage medium with a large number of codes that can be identified especially by reflection of light It is an object of the present invention to provide a method of duplicating media.

Therefore, one aspect of the present invention is to arrange a medium close to a photosensitive material, and to separate the incident light from the medium. The interference between the reflected light and the above-mentioned light-sensitive material is recorded on the data storage medium holographic The step of illuminating the medium with coherent light so that it can be replicated by A method for duplicating a data storage medium with a large number of codes that can be identified by reflected light. It gives

Photosensitive materials are usually transparent and the medium is illuminated with coherent light passing through the photosensitive material. It is better to

Preferably, the medium and the photosensitive material form an integral rigid structure.

The medium and the photosensitive material are preferably in contact with respective opposite parallel surfaces of the transparent plate. is suitably retained by the adsorption effect.

The method according to the invention can be applied to data storage media of various structures having a code that can be identified by reflected light. It provides a simple replication method that can be applied to any body. Photosensitive materials are at a high performance stage Even if it were, it would be in the form of photographic emulsion, which is much cheaper than the material for optical discs.

For media and films held as integral structures, vibrational and thermal The generated motion is considerably reduced, making it possible to use a table-top reproduction device.

A separate beam splitter can be created by using a new photosensitive material in the optical path. The need for This not only simplifies the duplication device but also It also forms a hologram that is read in the same way as used in .

An important advantage of the present invention is that holograms do not only contain data stored on a data storage medium. Typically, a tracking mark is provided to enable reading of the medium. The goal is to also copy the archive. for optical detection when reading conventional media. No matter what form of tracking mark is placed on the media for the purpose of It will be replicated as a hologram and appear in the reconstructed image. Kotogi Tora The image of the marking mark is a holographic image similar to the first mark when reading the media itself. would serve the same purpose in reading the system.

Especially when the rate of change of the data is small compared to the period of reading the data. Few erasable-rewritable disks can be used as working copies according to the present invention. Consider forms such as those used for data entry in holographic copies Can be done. This is especially true if you need to use many working copies at the same time. has economic advantages when used, and is itself sufficient to be used as a working copy. allows the use of dense storage media that are not durable and stable. be.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 schematically shows an apparatus for duplicating optical data storage discs according to the invention. FIG.

FIG. 2 is a diagram illustrating a method of reading a copy formed by the apparatus of FIG. 1.

FIGS. 3 and 4 are diagrams showing other reading methods.

Referring to FIG. 1, the data storage medium to be replicated is indicated at 10. this medium is the shape of a disk having a spiral track on the surface 10a, and the track The reflectance of is modulated in an appropriate manner. Disk 10 reads this using a conventional reading device. It has a central aperture 10b adapted to be mounted on the disc. It is used for positioning on the mandrel 12.

A circular transparent plate 14 of optical glass is disposed on the mandrel 12 coaxially with the disk 10. Ru. This transparent plate 14 has two exactly parallel opposing sides, one of which is The other side is in contact with the emulsion-bearing surface 16 of the photographic film of the disk material. come into contact with This film has a central aperture and is also positioned on the mandrel. be taught. The disk 10, the transparent plate 14 and the film 16 are firmly held together. An end cover 20 is provided between the disc and the film to provide an outer seal. Ru. The air inside the end cover is handled and each member is firmly pressed together by air pressure. An outlet 22 is provided for allowing the vibration to be removed. or the possibility of relative movement between the disc and the film as a result of factors such as thermal stress. A unitary rigid structure is provided which greatly reduces susceptibility.

A collimated laser beam is used to form a holographic replica of the disk. A beam of light is generated by a laser 24 and a beam expander 6. this beam is incident on the transparent film 16 in an undeveloped state. The optical characteristics of the transparent plate 14 are Most of the beam is chosen to minimize scattering and reflection at interfaces. is transmitted through the transparent plate 14. The light is reflected by the surface 10a of the disk, and this reflected light enters the A hologram is formed on the film by interfering with the incident light. More details on disk 10 Each symbol or pixel above can be seen as a secondary light source, which is generated by a plane incident wave. When irradiated, a fringe pattern is generated by generating a spherical wave that interferes with the incident wave in the plane of the photographic emulsion. form a turn.

Generally speaking, the size of the fringe pattern in a plane parallel to the optical axis is the size of the disk and emulsion. equal to the interval between. It is desirable to keep this distance small for the reasons listed below. However, enough fringes must be generated to form an actual hologram of pixels. There is a restriction that there is no. It is considered that the thickness of the transparent plate 14 is preferably about 1 mm. is being given. A three-dimensional hologram is formed with stripes spanning the thickness of the film. It can be understood that

Referring now to FIG. 2, one form of a reading device according to the invention is shown in schematic form. It is. The hologram 16 has a central drive pin 29 passing through its aperture. It is mounted on the disk mounting body 28. Attached to the hollow shaft 34 of the drive motor 36 The disk mounting body on which the hologram is placed is mounted so as to engage with the optical glass plate 32 A small ram 30 is provided for driving.

A tracking device 40 enters the hologram perpendicularly through a beam splitter 44. generates a laser beam bundle that radiates.

Since this beam is incident perpendicularly and is a parallel beam, at any moment there is only a small amount of light on the disk. Although only a small portion of the image is irradiated, the optical pattern of the recording process is duplicated. transparent An image of the first pixel is formed at a distance from the hologram equal to the thickness of plate 14. You will see that. Provide a reader that can also read the first disc. This distance should be kept as small as possible to make the laser device as usable as possible. Should be maintained within focus accuracy.

A detector or detection array 48 is provided with imaging optics 47 and a beam splitter. The image of the pixel can be scanned through 44. Tracking device radially Appropriate mechanisms are provided for movement.

Traditional optical disc readers typically read It uses an imaged laser beam.

In order to reduce the number of changes to the reading device, a different embodiment is shown in FIG. It has been proposed to use a synthetic light source. The tracking device 50 is an optical fiber The image of the pixel 56 is re-formed by illuminating the appropriate area 54 of the hologram, such as by using a A beam bundle 52 of white light is generated.

This is because the hologram is a three-dimensional hologram, not a two-dimensional hologram, so white light You will see that it is possible.

In addition, a conventional wide-screen system for reading the image re-formed by the detector 60 and the detection optical system 62 is used. An imaged laser beam 58 is formed, which is possible in a wide variety of ways.

FIG. 4 schematically shows another embodiment of the invention. This form is a diode It has the advantage of being compact and reliable. lens 72 is installed, which is a beam typically prohibited in diode lasers. Preferably, the lens is a stepped index lens to compensate for the divergence of the lens. disk The angle of incidence on the In this case, it is thought that the S/N ratio will be improved compared to the vertical sword. first re-image Separate illumination means (which may be white light) may be provided for the formation. this may be an image of the entire disk or simply an area containing pixels to be read. two The dimensional detection array 74 is provided with a detection lens 76 . Using a detection array Tracking will be improved.

Although the present invention has been described by way of example, various modifications may be made without departing from the scope thereof. It is. Thus, for example, a photochromic material can be formed in combination with a suitable etchable layer. Alternatively, other photosensitive materials such as photoresist materials can be used. For example, Photochromic materials are unique in that there is no change in refractive index or shrinkage caused by processing. It has advantages over photographic emulsions. The term ``photosensitive'' also refers to the incident laser beam. It is thought that it contains a plus deck material that is sensitive to the localized heat generated by the It will be done. simultaneous total exposure of the aforementioned film or other light-sensitive material The approach uses a narrower beam scanned over the plane of the disk. It can be changed to a sea urchin. It is also possible to use pulsed lasers. Must be duplicated If spurious reflections from the front side of the disk are difficult, A black matte coating can be applied.

The medium to be reproduced is assumed to have codes arranged in a spiral pattern. Although described, other arrangements are possible, such as concentric.

It is possible to provide an optimal distance between the medium and the photosensitive material to form an integral rigid structure. I explained the advantages of using a transparent plate. For example, commercially available compact It is clear that the disc has a transparent protective coating. The media is here. The protective coating itself acts as a transparent spacer plate when will.

There are also many other methods that produce an adsorption effect to hold the medium and photosensitive material together. You will see that there is a method.

In fact, other methods of forming integral rigid structures that do not use adsorption effects may be used. cormorant.

Since parallel light flux is considered to be advantageous, we have limited our explanation to this, but in some cases Other configurations may be appropriate, such as a diverging beam.

Although the invention has particular application to the reproduction of foul-read discs, other forms of Some aspects of the invention may then be advantageously applied. It is also formed almost as described above. In some cases, discs that have been read may be read in transmission mode rather than foul mode. similar Although the description was limited to disk-shaped media, the present invention is not limited to that. do not have.

international search report "ma+leMl^""-'"・PCT/GB 86100388

Claims (11)

[Claims] 1. A medium is placed close to the photosensitive material, and the difference between the incident light and the reflected light from the medium is The interference is recorded on the photosensitive material and is not reproduced by holography on the data storage medium. irradiating said medium with coherent light such that Method for duplicating a data storage medium with a large number of codes that can be identified by characteristic reflected light . 2. Claim No. 3, wherein said data storage medium is irradiated through a photosensitive material. The method described in Section 1. 3. The data storage medium and photosensitive material are held as an integral rigid structure. 2. The method according to claim 2. 4. The data storage medium and photosensitive material are retained by adsorption effect. The method according to claim 3. 5. The data storage medium and photosensitive material are placed on opposite parallel surfaces of the transparent plate. 4. The method according to claim 3, wherein the two parts are brought into contact with each other. 6. Claim 1, wherein said medium is irradiated with a normal incidence laser beam. The method described in section. 7. The cross-sectional area of the laser beam is approximately equal to the cross-sectional area of the data storage medium. 6. The method according to claim 6. 8. A medium is placed close to the photosensitive material, and the medium and the photosensitive material are integrated into a rigid structure. The photosensitive material is held in a structure and irradiated with coherent light. the step of producing a holographic reproduction of the data storage medium; Replicating data storage media with a number of optically readable codes featuring How to do it. 9. means for locating the data storage medium in close proximity to the sheet of photosensitive material; The interference between the incident light and the reflected light from the medium is recorded on the photosensitive material and the data is above with coherent light so that a holographic reproduction of the data storage medium is made. means for irradiating the medium; and a number distinguishable by reflected light, characterized in that A device for duplicating data storage media marked with 10. The means for arranging the data storage medium includes the data storage medium and the storage medium. It includes a means for holding the sheet-like photosensitive material so as to form an integral structure. 9. The apparatus according to claim 9. 11. A hologram of a data storage medium formed by the method according to claim 1. A disc that is a reproduction by Raffi.