WO2006120292A1

WO2006120292A1 - Device and method for supporting optical recording medium during read/write operation

Info

Publication number: WO2006120292A1
Application number: PCT/FI2006/000155
Authority: WO
Inventors: Samuel Holm; Teppo Sahlberg; Tuomas Mustonen
Original assignee: M-Real Oyj
Priority date: 2005-05-13
Filing date: 2006-05-12
Publication date: 2006-11-16
Also published as: FI20050514A; FI20050514A0; FI119488B

Abstract

The publication describes a device (42, 44) for supporting an optical recording medium (40) during a reading or writing event, a method for making an optical recording medium (40) optically readable, and an optical reading device. The device (42, 44) comprises means for positioning the recording medium (40), in such a manner that it can later be removed, in the device, in such a way that the device, together with the recording medium (40) forms a planar totality, which can be rotated around an axis at right-angles to the surfaces of the recording medium (40) in order to read information through the surface of the device from the recording surface of the recording medium (40), or in order to write information on the recording surface of the recording medium (40). According to the invention, the device (42, 44) comprises fine structures (45), which can be utilized when reading from or writing to the optical recording medium (40).

Description

Device and Method for supporting optical recording medium during read/write operation

The present invention relates to optical discs. In particular, the invention relates to a device, by means of which an optical medium / optical recording medium can be supported while being read from or while being written to.

A device of this kind comprises means, with the aid of which an optical recording medium can be positioned in a device, so that it can be read from or written to optically. The optical recording medium can have a base of, for example, plastic, paper, or board.

In addition, the invention relates to a method for distributing information recorded on an optical medium, and to an optical reading or writing device.

Optical discs have traditionally be manufactured mainly from polycarbonate, in which optically readable data is incorporated, for example, by printing relief images on it. For example, CD discs are manufactured from polycarbonate discs about 1.2-mm thick, into one surface of which are pressed pits of varying size, which contain the desired data in digital form. On top of the relief imaging a light-reflecting layer is placed, on top of which again a protective lacquer layer is arranged. Such discs are read from the direction of the 'rear surface' of the polycarbonate disc, so that a laser beam travels through the polycarbonate layer and is reflected back from the reflective layer. The discs have a hole in their centre, to enable them to be rotated. Polycarbonate discs are rigid (self-supporting), so that they can be placed as such, for example, into a CD player.

WO publication 2006/027417 discloses an optical disc, which is manufactured on a base of paper or board. By using thicker board, such a disc can be made rigid, but when using thinner substrates, for example, paper, the disc is often flexible (non-self-supporting). However, during the reading event the disc must remain very flat, so that the focus of the reading laser will remain on the surface of the data portion of the disc. During reading or writing, flexible discs must be supported inside the reading or writing device. The data portion can comprise, for example, relief images made in a polymer layer on the surface of the paper, as well as a reflective layer arranged on top of this. Though such a disc is cheap to manufacture, the disc will have to be read 'straight off the surface', in such a way that the reading layer strikes the reflective layer without travelling through the thick plastic layer, which will mean that the disc construction will not necessarily be compatible with all reading devices/players, due to its physical or optical characteristics.

JP patent publication 2003085912 discloses a device consisting of two parts, inside which an optical recording medium can be located. Though the construction of the recording device resembles that of a traditional optical disc read from the read surface, as described above, it is, however, considerably thinner. The parts are circular in shape and disc-like, and attachments are arranged in them, by means of which they can be secured inside each other, in such a way that the optical recording medium remains between the discs, so that it is optically readable, when the device together with the disc is rotated in the reader. There are at least four attachments, which are placed symmetrically on the external and/or internal rims of the discs. To detach the recording medium from between the discs, several of the attachments must be twisted simultaneously while the discs are rotated relative to each other, which makes it difficult to detach the discs from each other and in practice demands a device designed for this purpose. Publication US 2004/0210920 discloses a device of the same type. Further, an improved device, though of the same type, is disclosed in EP publication 0420304. In it the discs can be equipped, for example with threads, to facilitate their installation and removal.

US application publication 2001/0036148 discloses an adapter, in which a small-sized CD disc can be placed to permit it to be read in a conventional CD player. The adapter forms an outer ring to the disc, in which ring there can be a data portion, the small-sized disc being set inside the outer ring in such a way that it form the central part of the disc.

The devices described above are intended to adapt the recording medium only mechanically to the reader, and cannot be used to improve the compatibility of surface- readable optical discs with various players and different optical-disc standards.

In addition, several disc cases are known, in which an optical disc is arranged to rotate inside a case pushed into a rectangular optical reader (e.g., MiniDisc). In these solutions, the case itself does not thus rotate along with the disc during the reading event, nor can be disc in the case be changed. Such a device is disclosed in, for example, publication US 2002/0071375.

Digital information can be contained in thin paper or board-based recording media. These are often flexible, i.e. they do not remain flat when they are carried, so that they cannot be read as such in conventional optical readers. In addition, fibre-based discs are liable, for example, to variations in ambient humidity, which can lead to the discs buckling or warping. This in turn makes it difficult to read them reliably. However, in many fields, the use of such discs has, however, many ecological and economical advantages. Thin recording media are disclosed in publications US 2003/0108710 and US 5579296.

The invention is intended to eliminate the defects of the state of the art disclosed above and for this purpose create a new solution for permitting the optical reading or writing of optical recording media.

The invention is also intended to create a device, which will improve the compatibility of optical recording media, read from the surface, with reading or writing devices.

In addition, the invention is intended to create a device, which can be used to distribute large amounts of information in an environmentally- friendly and economical manner.

The intention is also to create a new method for permitting the reading and writing of thin paper and board-based recording media.

In the device according to the invention, there are means for positioning an optical recording medium in a device, so that it can be later removed, in such a way that the device together with the recording medium forms a planar totality, which can be rotated around an axis at right-angles to the surfaces of the recording medium in order to read information for the recording surface of the recording medium, or to write information onto the recording surface of the recording medium. In addition, the device comprises optically detectable fine structures. The term optically detectable fine structures refers to micro and nano-level structures, generally pits, bumps, or flat areas, which can be read with the aid of a laser beam when the disc rotates at reading or writing speed. Thus, with the aid of them laser light can be scattered into the environment or the detectable part of the light can be reflected back to the incoming direction of the laser. The structures can be implemented as physical variations in the height of the surface of the device, or, for example, by arranging materials with different reflectivities on some surface or inner layer of the device. The optical recording medium to be fitted to the device comprises a thin disc, which has two surfaces, at least one of which is such that is contains, or on which can be written, optically readable data. This surface is also termed the recording surface.

According to the invention, information in a digital form on a paper or board-based optical recording medium can be made optically readable by using a device, which comprises means for positioning the optical recording medium, so that it can later be removed, in the device, in such a way that the device, together with the recording medium forms a planar totality, which can be rotated around an axis at right-angles to the surfaces of the recording medium, in order to read information from the recording surface of the recording medium, or to write information to the recording surface of the recording medium. The optical recording medium is positioned in the device in such a way that it becomes rigidly flat. The device containing the optical recording medium is rotated in the optical reader, in order to read the information recorded on the recording medium.

The optical reading or writing device according to the invention comprises means for reading from or writing to an optical recording medium placed in the clamping device, which clamping device comprises a first and a second mounting elements, between which the recording medium can be positioned and made essentially immobile, at least relative to the second element. In the device, there is a space protected from dust, in which the recording medium attached to the clamping device is arranged and means for detaching the first or second mounting element from the clamping device, in order to reveal the recording surface of the recording medium for reading or writing.

More specifically, the device according to the invention is characterized by what is stated in the characterizing portion of Claim 1.

The method according to the invention is characterized by what is stated in the characterizing portion of Claim 13. The optical reading device according to the invention is characterized by what is stated in the characterizing portion of Claim 21.

Considerable advantages are gained with the aid of the invention. With the aid of it, for example, paper-based optical discs, which would otherwise be too thin or flexible, can be used in conventional optical readers/players/writers. Paper-based optical discs are, in turn, environmentally friendly, on account of the biodegradable materials used in them. In addition, they can be manufactured on conventional paper-production and printing lines capable of making large volumes. The devices can be supplied, for example, along with magazines, without them significantly increasing the weight, and thus the delivery costs of the magazine. The devices can be delivered, for example, automatically to new subscribers, or they could be sold by newsagents.

By combining the dimensional and optical fitting of the recording medium with the device construction according to the invention, it is possible to reduce the manufacturing costs of the actual recording media while at the same time permitting more diverse applications.

The device can be economically and easily manufactured, for example, from two mounting elements (also 'clamping plates'). Here these are termed the first and the second mounting element. Hereinafter in this document such a manner of implementation will be used as an example, for reasons of clarity. It is, however, obvious that a device comprising corresponding properties permitting reading or writing can also be manufactured from one or more elements, with the aid of appropriate design.

One important area of application of the device is video rental. Video rental shops can, for example, give new customers the clamping plates and then supply films on paper-based discs with minuscule material costs, which customers themselves can place between the clamping plates before viewing the film. After use, the disc can be ecologically disposed of along with paper or household garbage. Once the optical recording medium has been inserted in the device, the device will also protect the medium from scratches, impacts, and dust.

In the case of paper-based optical recording media, not only is their lack of rigidity a problem, but also possible warping and buckling of the discs, for example, as a result of ambient humidity. The device according to the present invention can be made such, that the recording medium is straightened in the device, to become optically readable. For example, when using the aforementioned mounting elements, these cause a compressive force to act of the recording medium between them, the magnitude of which is sufficient to both straighten (stiffen) the medium, and to hold it essentially immovably relative to the first mounting element, when reading or writing.

The device according to the invention can be arranged to be compatible with very many existing optical-disc formats, standards, and reading devices. The invention can be applied, for example, in connection with CD, DVD, Blu-ray, and HD-DVD technologies. Alternatively, the device can be used with disc formats designed specifically for it.

The term optically detectable fine structure, located in the first mounting element, refers to nano and micro-level structures (hereinafter also 'micro-structures'), which can be detected by laser light. The optically detectable structures can contain, for example, structures for facilitating the reading or writing of the disc, such as a lead-in groove, data directing the reading of the disc, such as a lead-in or lead-out partition, or, for example, sound, image, video, or data files, or some combination of these.

As stated above, the term clamping plates is used for the first and second mounting elements that are used together. Particularly the second mounting element need not, however, be disc-like, but can instead be shaped in some other way, in such a way that the optical recording medium can be locked into the device. According to a preferred embodiment, at least the first mounting element is, however, essentially disc-like, to facilitate the optical reading or writing that takes place through the element. In addition, either the second mounting element, or both mounting elements when connected together provide an advantageously rigid base, with the aid of which thin and flexible, for example, paper or board-based recording media can be arranged flatly, for optical reading or writing. The compression force directed by the mounting elements onto the recording medium is preferably great enough for the recording medium to remain essentially immovable at least relative to the first mounting element, when the device is handled, accelerated to the reading or writing speed, and rotated in a reading device. Immobility can, of course, be achieved even without considerable pressure, for example, with the aid of the suitable shaping of the recording medium and the mounting elements.

The second mounting element can be entirely detachable from the first element, or it can be pivoted to it, in such a way that recording media can be placed between the elements. The ability of the mounting elements to be detachable later refers to the ability of the device to lock the recording medium relative to the mounting elements and to release it later from the device. In some cases, there can also be several second mounting elements.

Once the recording medium has been placed in the device, the device is flat. In this connection, flatness should be understood to mean that the device is sufficiently thin to be fed into such an optical reading or writing device, in which it is intended to be readable or writable, for example, a CD, DVD, HD-DVD, or Blu-ray drive.

Hereinafter, the words 'disc element' and ' disc' will also be used for the first and second mounting elements.

In the following, the invention is examined in detail with reference to the accompanying drawings, in which

Figure 1 shows a cross-section of the clamping plates according to the invention, between which is the recording medium and the reading device,

Figure 2 shows a schematic cross-section of an optical disc according to the DVD-9 standard,

Figure 3 shows a schematic cross-section of and optical disc according to the DVD-5 standard,

Figure 4 shows an exploded view of clamping plates according to the invention, the second of which comprises an optically detectable portion, and

Figure 5 shows a cross-section of a device construction according to one preferred embodiment of the invention.

Figure 1 shows clamping plates according to the invention in a reading device. In it, the optical recording medium 10 is arranged between the disc elements 12 and 14 in such a way that they form a rigid totality. The discs 12 and 14 can be dimensioned in such a way that the external dimensions of the disc structure implement the demands, for example, of some standard laid down for optical discs. Similarly, the straightness, stiffness, and optical properties of the discs can be adapted to accord with standards, with the aid of material selections and the manufacturing technique used, so that the optical medium 10 can be reliably read, or new information can be reliably written on it.

In a typical embodiment, at least the first element is essentially circular in shape. The diameter of the device once it is made ready for operation (reading/writing readiness) can be, for example 120 mm or 80 mm, so that it will be suitable for use with the most common optical disc formats. The thicknesses of the first and second elements can be selected according to the operating purpose. In a typical application, the thickness of the device when ready for use will be about 1.2 mm. However, the device according to the invention is not restricted to the disc formats referred to above or to those already known, but instead other shapes and sizes of disc elements and devices can, of course, be used.

The optical recording medium set between the clamping plates can be made, for example, from a plastic or paper substrate. The optical structures contained in it can be, for example, relief-printed directly onto the substrate, or on a polymer layer applied on top of it. Beneath and/or on top of the relief patterning a protective and/or reflective layer can be arranged. The thickness of the recording medium can be about 0.03 - 0.5 mm, preferably about 0.08 - 0.2 mm. If a paper or board- based recording medium is used, the net weight of this can be, for example, 30 - 400 g/m². However, in order to save material costs, it is advantageous to use thin paper recording media, the grammage of which can be, for example, 50 - 150 g/m².

According to one preferred embodiment, at least the second disc element is manufactured entirely or partly of a compressible, preferably elastic material, so that its thickness will always change according to the thickness of the recording medium. The advantage of this embodiment is that the thickness of the clamping device will not change according to the thickness of the recording medium, but instead recording media of different thicknesses can be used with the same clamping plates. In addition the compressible layer will improve the contact between the recording medium and the clamping device. According to one embodiment, at least the second disc is formed, in the direction of the thickness of the disc, partly of a hard material and partly of a compressible material. The relative proportions of the hard and the compressible materials in the thickness of the disc can be, for example, 1 :4 - 4: 1. In that case, the hard material can be, for example, a 0.3-mm layer and the compressible material a 0.3-mm layer. According to another embodiment, different kinds of clamping plates are made for recording media of different thicknesses, or, for example, only the second disc element can be manufactured for recording media of several different thicknesses.

The elements 12 and 14 can be attached to each other in several different ways. According to one embodiment, which is also illustrated in Figure 1, the outer circumference of the second (lower) disc 12 has a flange 11, which is can be fitted against the outer edge of the first (upper) disc 14. Correspondingly, on the inner circumference of the first disc 14, there is a flange 13, which can be fitted against the inner edge of the second disc 12. The flange on the inner circumference of the first disc 14 also forms a hole, which can be used to assist the rotation of the disc around its axis of rotation in the reading or writing device. The flanges of the first and second discs, and the edges that lie against them can, in addition, be equipped with mounting elements, for example, bumps and pits, or with threads, to ensure that they remain attached. Thus the discs 12 and 14 can be easily separate from each other in order to release the optical medium 10, by pressing the discs in the direction opposite to that of the axis of rotation, or by rotating them relative to each other around the axis of rotation. With the aid of the solution described, it is possible to create a disc construction that is flat on both surfaces, the appearance of which greatly resembles that of a traditional CD or DVD disc.

At least one of the discs 12 or 14 is preferably manufactured from a material that is transparent to the wavelength of the laser light used, preferably from some polymer material. Suitable materials are, for example, polycarbonate and polymethyl meta acrylate (PMMA). Polycarbonate is a widely used and economical material for optical discs, whereas the optical properties of PMMA, such a light transmissibility, are in some applications more advantageous than those of polycarbonate. The price of the material is also not such a critical factor as it is with traditional optical discs, as the same clamping plates can be used hundreds or even thousands of times by changing the optical recording medium between them.

At least the disc 12 and 14, through which the medium 10 is read, is, according to a preferred embodiment made to be antistatic. This will reduce the collection on the surface of the disc of dust that interferes with the reading event. The antistatic property can be achieved through the choice of the base material of the disc, by adding some agent or several agents, which reduce the collection of a charge in the disc, to the disc material, or by surfacing the disc with some antistatic material. Such a surfacing can be located on the outer or inner or both surfaces of the disc.

The optically detectable fine structure can be located in either of the discs. According to one embodiment, the optically detectable structures are located on the inner surface of the first disc, i.e. on the inner surface of the disc, from the direction of which the optical recording medium is read (in the case of Figure 1, disc 14). The optically detectable structures can be semi-transparent (semi-reflective), or opaque (reflective).

Figure 4 shows an example of a disc arrangement, in which the first disc 42 forms the cover of the disc and the second disc 44 its undersurface, through which the optical medium 40 is read. Optically detectable structures 45 are contained in the second disc 44.

The optically detectable structures can be, for example, grooves, which are micro- machined, for instance relief-printed or laser-machined, for example, in the inner surface of the disc. If the optically detectable structures contain data, they comprise pits and flat areas preferably arranged in the form of a spiral path.

Figure 5 shows one preferred embodiment of the invention. In the figure, the dimensional relations of the various material layers are arbitrary and, for example, the optical fine structures are shown with an exaggerated size relative to the thickness of the device, for reasons of clarity. The first element 54 comprises a body 55, the inner surface (the upper surface in the figure) is micro-machined. On top of the micro-machined surface a semi- transparent of reflective layer 56 is applied. On top of the semi-transparent layer 56 is a protective and evening layer 57. The layer 57 can be, for example, a lacquer layer. The optical recording medium 50 is placed against the protective layer 57, in such a way that its optically readable (micro-machined) surface and the lacquer layer 57 lie against each other. The recording medium 50 is held in place by the second disc element 52 (the attachment mechanism is not shown). In the solution according to the figure, the data area of the recording medium 50 is greater than the fine-structure area of the first element 52. The semi-transparent layer can be arranged either only in the fine-structure area or on a larger area, as is shown in Figure 5.

The construction of the first element according to Figure 5 resembles a traditional optical disc. If a semi-transparent layer is used on top of the micro-machined area, the optical recording medium can also be read from these locations. The micro-machined area will form, for example, the first data layer according to the DVD-9 standard and the optical recording medium the second data layer. The disc construction according to the DVD-9 standard and the reading of the disc are illustrated roughly in Figure 2, in which the first data layer is marked with the reference number 22 and the second data layer with the number 20. The laser beam 26 is to show the reading laser focussed on the first data layer 22, which is semi-transparent while the laser beam 24 shows the reading laser focussed on the second data layer 20, which is reflective.

The construction of a DVD-5 disc is illustrated in Figure 3. In a disc of this kind there is only a single data layer. According to one embodiment of the present invention, the clamping plates and the optical recording medium placed between them form a disc according to the DVD-5 standard, or some other single-layer disc construction. In that case, from the point of view of the reading device, the optically readable fine structures contained in the clamping plates and the structures contained in the optical recording medium can be located in the same layer, so that the device need not re-focus the reading laser.

The optically detectable portion can contain control data to facilitate the reading of the disc, such as a lead-in partition, other data, or both control data and other data. In CD and DVD disc constructions, the lead-in partition comprises, for example, data on the tracks on the disc and their starting locations on the disc. Within the scope of the present invention, the lead-in partition on the clamping plate could, for example, direct the reading laser to read directly from the second data layer (i.e. the optical medium, for example, a paper disc, fitted between the clamping plates). In this embodiment, it is indeed possible to envisage using the clamping plates to 'fool' the reading device into thinking that the disc is, for example, a dual-layer disc according to the DVD-9 standard.

According to one embodiment, the clamping plates are manufactured to be such that the optical recording medium can be read from both sides of the disc. The optical recording medium will then naturally be manufactured to be dual-sided. The device can be designed applying the principles referred to above, for example, to be such that, in combination with the recording medium it will conform to the DVD-9 standard. In that case, both disc elements will preferably comprise optically detectable microstructures. If the discs are made for discs that are to be read from one side, the shape or material of the second disc element will not be of great significance, as long as the optical recording medium is locked sufficiently well between first discs, when the elements are attached to each other. The second elements can be, for example, 'star-shaped', so that it comprises radial elements, which extend from the centre towards the circumference, or from the circumference of the disc towards the centre. In the case of dual-sided recording media, the second disc element too is preferably manufactured to be, at the location of the reading device, entirely of uniform thickness and transparent.

According to one embodiment, the optically detectable portion comprises data that complements the information contained in the optical recording medium, or without which the recording medium to be placed between the clamping plates cannot even read, or at least interpret the information contained in it. A data portion of this kind can be made, for example, to protect the optical recording medium from being copied, or to make this difficult. In the data portion there can be, for example, some essential program, part of a program, or authentication, without which the data of an optical recording medium made for the clamping plates cannot be read. Such a program or authentication can comprise, for example, an encryption key. The clamping plates and the optical recording media can then be made to be such that, without the one the other will be useless. This embodiment can be exploited, for example, in computer-game, console-game, or video-rental businesses, or, for example, to ensure that the information content of optical recording media supplied with magazines cannot be read by others than subscribers to the magazine. According to one embodiment, the optically detectable structures comprise a pre-groove. Pre-grooves are widely used in writable (-R) and re-writable (-RW) CD and DVD discs. The task of the pre-groove is to assist the writing laser to remain on a spiral path when writing to the disc. Naturally, it should then be such that its location can be detected by optical methods. The advantage of this embodiment is that even such writable and rewritable optical recording media, which do not themselves include a pre-groove, can be used in conventional optical writers (i.e. 'burners'). Thus such devices can be economically manufactured, for example, on paper, board, or plastic film.

The clamping plates can be manufactured, for example, by injection moulding from a plastic material, such as polycarbonate or PMMA. The desired optically detectable structures are preferably made in connection with the injection moulding. The optically detectable structures can also be manufactured in a separate process stage, for example, with the aid of laser machining or relief printing. After machining, the structures can be surfaced with a reflective or semi-transparent layer, which can comprise, for example, aluminium, silver, or gold. The surfacing can be applied, for example, by deposition or sputtering. The optically detectable structures can also be put onto the discs as a separate layer, for example, with the aid of a laminate, in which case the reflective or semi- transparent layer can be contained in the laminate, or it can be put on as a separate layer. Other layers improving the optical or mechanical properties of the discs can also be added to the discs.

The clamping plates can be attached to each other with the aid of attachment means in them. The attachment means can comprise flanges 11, 13, according to Figure 1, in the external and/or internal circumference of the discs. The flanges can be shaped in such a way that the discs can be easily attached to each other and separated from each other. They can be, for example, equipped with threads, catches, or small bumps and corresponding pits, in such a way that the discs lock onto each other by pressing and/or by rotating. The attachment of the discs can also be implemented without flanges, for example, in the manner disclosed in JP patent publication 2003085912. In that case, there are openings in one disc, into which protrusions of the other disc can be set and locked. The attachment means are preferably shaped in such a way that both surfaces of the device remain essentially flat once the discs have been attached to each other. According to one embodiment, the first and second elements can be attached to each other and/or separated from each other mechanically, for example, in the disc reader or writer. In that case, the elements can be designed to be such that the optical recording medium remains attached to either the first or the second element. This will permit the optical recording medium to be mechanically inserted or removed and for the medium to also be read form or written on directly from the surface, as the disc element between the reading device and the recording medium has now been eliminated. However, at least one of the disc elements must be arranged to rotate along with the recording medium. Particularly in connection with the Blu-ray and HD-DVD technologies, this embodiment can be advantageous, as in these disc types the data layer is located closer to the surface of the disc than in the CD and DVD disc types. Alternatively, in connection with Blu-ray and HD-DVD, the disc element, through which the recording medium is read, can be made extremely thin, so that both disc elements will rotate along with the recording medium when reading it.

Clamping plates, which can be separated from each other mechanically, can be of benefit particularly in connection with very high resolution disc technologies, as in high-resolution applications (e.g., Blu-ray and HD-DVD) scratching and dust accumulation are more liable to prevent discs being read than in the case of lower resolution applications (e.g., CD and DVD). For example, it is possible to manufacture players, which remove the first disc element, in order to read the data contained in the recording medium directly from its surface. In addition, players can additionally at least partly have an excess pressure inside them, to prevent dust accumulation when the second clamping plate has been removed. This embodiment thus permits a new type of optical disc arrangement, which does not require, for example, the use of the cartridges known from MiniDisc discs, to protect the optical disc rotating inside the cartridge.

According to one embodiment, the clamping plates are designed to be such that, with their aid, the optical recording medium can be 'cut' to shape from a disc blank comprising the recording medium and placed between the discs. In that case, the actual recording medium need not be touched by hand. One of the discs can, for example, include a separation surface or separation area on the circumference of the disc, so that when pressing or rotating the discs together the recording medium detaches from the blank and remains between the clamping plates.

According to a preferred embodiment of the method according to the invention, information in a digital form is arranged on a thin optical recording medium, which is made on a paper or board substrate, and the recording medium is fitted between the clamping plates in order to make it optically readable. The term 'thin' optical recording media refers, for example, to recording media that are not self-supporting, and thus cannot as such be optically readable, so that their stiffening is essential in order to permit them to be read in a conventional optical reading device, such as a CD or DVD player, or a computer. The recording medium can also be self-supporting, but it may be advantageous or even essential to straighten or stiffen it, in terms of reading or writing.

Digital information can be arranged on the recording medium either before it is placed in the clamping device, or only after it. The digital information can comprise, for example, sound, image, or video files, or other data. It can be arranged on the recording medium, for example, by relief printing. In that case, it is preferable to apply an even, relied-printable polymer layer to the substrate. Alternatively, the recording medium can be micro- machined in other ways, for example, with the aid of a laser, lithographic methods, or etching. Other embodiments and advantages of paper-based optical discs are disclosed in WO publication 2006/027417.

The recording medium can be such that information can be recorded on it with the aid of laser light. Typically, the recording medium will then comprise at least one substance, the structure or composition of which can be influences by powerful laser pulses. Many such recording colouring agents are known, for example, in connection with CD-R and DVD+/- R technologies. The colouring agent can be arranged, for example, in a pre-groove arranged in a polymer layer on top of the substrate, in which case a pre-groove will not be needed when writing to the disc on the clamping device. Alternatively, the pre-groove can be in the clamping device, in which case the manufacture of the recording medium will be simplified.

The device used in the method can comprise, for example, the device described earlier in this document. The device can thus include optically detectable structures for making the recording medium optically readable. This is preferable, for example, in sector or company-specific applications. In this way it is possible, for example, to ensure in film sales and rental businesses, that the discs supplied can be read only within the clientele of the company. The cheap and environmentally-friendly recording medium need not necessarily be returned to the rental company after 'rental'. Such compressed discs are, however, difficult to counterfeit. The film industry would benefit from this embodiment, as in this way it is possible to prevent recording media containing films from entering 'circulation'.

According to one embodiment, the clamping device is supplied to customers equipped with ..individual codes or lead-in data. Thus it is possible to supply, for example, films to customers, in such a way that their viewing will require the clamping device of precisely the customer in question and it will be impossible to view films with the wrong device. The device can include, for example, a writable portion, in which the individual code or lead-in portion is recorded before the device is supplied. On the basis of the rental company's customer register, or by bringing the clamping device to the rental company, films can be written on a paper or board substrate to be suitable for the device of the customer in question. The lead-in partition can contain, for example, data on the starting point for reading the disc. The manner of protection can, of course, also be different. For example, the reading device can check that the codes recorded on the clamping plates and the recording medium correspond, before starting to play the film. By utilizing the principles described above, it is possible to implement tailor-made applications for other sectors of business and industry too.

The optical recording medium can be arranged between the discs, either by the company supplying the disc, or only at the customer's home. For example, it is possible to construct a device, to which the customer can feed their own clamping plates, after which the device burns a film on the recording medium on the basis of what the customer has fed, places it between the clamping plates, and returns it to the customer in an optically readable form. The device can also output the cover information on the film, and/or other information on the second side of the recording medium. The clamping plates can be such that they can _. only be opened mechanically, in which case the system could also act as an effective recycling system for discs that have once been viewed - and also for the clamping plates. The clamping plates could be purchased, for example, for a small sum of money, or against a deposit from the checkout of the film-rental company or newsagent. If the device is such that customers themselves can place the recording medium in the device, the recording media can also be supplied by mail, for example, on the basis of an order placed through the internet.

Claims

Claims:

1. A device for supporting an optical recording medium during a reading or writing event, which optical recording medium comprises a thin disc having two surfaces, of which at least one is a recording surface, the device comprising means for detachably positioning the recording medium in the device, in such a way that the device, together with the recording medium forms a planar totality, which can be rotated around an axis perpendicular to the surfaces of the recording medium in order to read information through the surface of the device from the recording surface of the recording medium, or in order to write information on the recording surface of the recording medium, characterized in that the device comprises fine structures, which are optically detectable when rotating the device around said axis.

2. The device according to Claim 1, characterized in that it comprises

- a first planar mounting element, which has an inner surface and an outer surface and against which inner surface the recording surface of the optical recording medium can essentially be entirely fitted, and

- a second mounting element, which can be removably attached to the first mounting element, in order to attach the optical recording medium to the device, and the optically detectable fine structures are located in the second surface of the first mounting element.

3. The device according to Claim 2, characterized in that the first and second mounting elements comprise means for removably attaching them to each other.

4. The device according to Claim 2 or 3, characterized in that the thickness of the first mounting element measured at right-angles to its inner and outer surface is, in the area of the optical recording device, about 0.6 mm or 0.1 mm.

5. The device according to any of the above Claims, characterized in that the optically detectable fine structures comprise at least one groove.

6. The device according to Claim 5, characterized in that the groove form a spiral pre- groove, in order to promote the reading or writing event of the optical recording medium.

7. The device according to any of Claims 1 - 5, characterized in that the optically detectable fine structures contain digital data.

8. The device according to Claim 7, characterized in that the digital data comprises at least part of a lead-in or lead-out partition, in order to promote the reading event of the optical recording medium.

9. The device according to any of the above Claims, characterized in that the optically detectable fine structures comprise a separate reflective, semi-transparent, or transparent layer.

10. The device according to any of the above Claims, characterized in that, once the optical recording medium has been positioned in the device, the device is flat and essentially circular in shape, the diameter of the device is about 80 mm or 120 mm, the thickness of the device is about 1.2 mm, and there is a central hole in the device with a diameter of about 15 mm.

11. The device according to any of the above Claims, characterized in that it is at least partly manufactured using a polymer material transparent to the wavelength of the reading or writing laser.

12. The device according to any of the above Claims, characterized in that it is at least partly manufactured from an elastic material, to eliminate the effect of the thickness of the recording medium on the dimensions of the device.

13. A method for making information is a digital form optically readable, characterized in that the method comprises a combination of the following stages:

- the digital information is arranged in an optical recording medium, which comprises a thin paper or board substrate, and which has two surfaces, at least one of which is a recording surface, and - a device is taken, which comprises means for detachably positioning the recording medium in the device in such a way that the device, together with the recording medium forms a planar totality, which can be rotated around an axis perpendicular to the surfaces of the recording medium, in order to read information from the recording surface of the recording medium through the surface of the device, or in order to write information on the recording surface of the recording medium, and

- the optical recording medium is fitted to the device, in such a way that the device stiffens the optical recording medium in order to make it optically readable.

14. The method according to Claim 13, characterized in that a substrate is used, on at least one surface of which a polymer layer is arranged, which can be microfabricated in order to record optically detectable information.

15. The method according to Claim 13 or 14, characterized in that an optical recording medium is used, on which information can be arranged with the aid of a laser.

16. The method according to any of Claims 13 - 15, characterized in that a single apparatus is used, which performs all of said stages.

17. The method according to any of Claims 13 - 16, characterized in that the digital information is arranged in the optical recording medium after it has been attached to the device.

18. The method according to any of Claims 13 - 16, characterized in that the digital information is arranged in the optical recording medium before it has been attached to the device.

19. The method according to any of Claims 13 - 18, characterized in that a device according to any of Claims 1 - 12 is used.

20. The method according to any of Claims 13 - 19, characterized in that digital data, which is used to permit the reading of the optical recording medium, is arranged in the device.

21. A device for reading from or writing to an optical recording medium, which device comprises means for reading from or writing to the optical recording medium, and in which recording medium there is at least one recording surface and which recording medium can fed into the device, set in a clamping device, which clamping device comprises a first and a second mounting element, between which the recording device is positioned and made essentially immobile relative to at least the second element, characterized in that

- in the device there is a space protected from dust, in which the recording medium attached to the clamping device can be arranged, and

- in the device there are means for detaching the first or second mounting elements from the clamping device, in order to reveal the recording surface of the recording medium for reading or writing.

22. The device according to Claim 21, characterized in that the space is protected from dust with the aid of overpressure.

23. The device according to Claim 21 or 22, characterized in that the clamping device comprises a device according to any of Claims 1 - 12.