MXPA99005423A - An optic device for the limited reproduction of sonorous registers - Google Patents

Abstract

Se describe un disco compacto de uso limitado en el que el número de veces que se puede leer el disco es limitado. Esta característica de lectura limitada se logra mediante la utilización de un material fotocromático o por medios eléctricos. También se describen métodos para fabricar tales CDs de lectura limitada.

Description

OPTICAL DEVICE FOR. THE LIMITED REPRODUCTION OF SOUND RECORDS Technical Field This invention relates to an optical device for the limited reproduction of sound records, such as a compact disc. More specifically, the invention relates to the inclusion of a low energy photochromic material in an optically readable device, which limits the number of times the device information can be obtained. Numerous photochromic materials and methods have been described to incorporate the photochromic material into the device.

Background In the digital world of today, all kinds of data are stored in digital form, such as in computer software, databases, audio data and video data. Currently, the compact disc (CD) is the storage medium that is most used due to its ability to store large amounts of data, its exceptional quality, ease of manufacture and long-term durability. Since it was first released in 1982, more than ten million CD players have been sold in the United States and more than a billion compact discs worldwide. Most computers sold today also include a CD-ROM drive (compact disc, Memory Only Memory unit) for software, games and multimedia presentations. "Reading Only" means that one can only see the contents of the CD-ROM; the information that is on the disk can not be altered. In contrast, "writable" or "CD-R" discs are those in which "information" can be "altered" in numerous formats. A CD is a medium in which large amounts of information can be stored. Standard CDs can be viewed as very large soft disks protected so that nothing can be recorded on them. Currently, CD players are selling at a rate of more than 1 million per year, which makes CD players the fastest growing electronic product ever introduced for sale to the consumer.

With the extensive use of the compact disc as a means to store data, the compact disc is an excellent means for merchants and sellers to advertise their products. Currently, retailers distribute compact discs with software to induce the consumer to sign up for their service (for example, America On-Line) or to advertise their services or products. However, there is currently no way to limit the use of a compact disc. For example, once the consumer obtains a compact disc with software, he can use the software indefinitely or until the compact disc is broken or damaged without being able to repair it. Consequently, there is a need for manufacturers to have a practical way to limit the use of a compact disc; more specifically, to avoid recovering data from a compact disc after using a predetermined number of times. For example, with regard to audio compact discs, it would be an advantage to adapt a compact disc to prevent the user from listening more than one (1) time to the audio disc. Such a limited use compact disc will also allow the consumer to try a video game before deciding whether to buy the disc or not. The limited use feature described in this invention will prevent the user from using the disk after a predetermined number of times. After knowing the information that contains the CD, the consumer will be able to buy from the seller, if he wishes, an unlimited version of the CD to reproduce it. Thus, among other advantages, a limited use compact disc will allow merchants to distribute "demonstration CDs" to the consuming public with the aim of marketing new products, computer games, software and music recordings, with security that the demo disc can not be used after a predetermined number of times.

In accordance with the present invention, another embodiment of the limited use CD would be to limit the number of times that only a portion or track of the data on the compact disc could be recovered. The advantage of this limited reproduction section of a compact disc is obvious when you think of the example of a limited reproduction ad added to a music compact disc. The limited playback feature of the ad is designed to make the ad more acceptable to anyone who is listening to the compact disc. The attraction for the advertiser is that if you know the specific tastes of the audience of the compact disc, anyone who has knowledge in the field of advertising could specifically create the ad to better reach those people than other means of advertising. This will greatly improve the effectiveness of the advertisement. The ability to specifically target advertising to the market is the main objective of any advertisement. This improved choice of targets will make this technology a much more preferred form of advertising than other existing ones in the world market, in which more than $ 50 billion are currently spent annually on advertising.

In its most general form, the limited use compact disc of the present invention includes a photochromic material that is deposited on the disk, or on a portion thereof, which converts it from relatively transparent to relatively opaque upon contact with the disk. reading radiation. Photochromic material means a material that is capable of changing color when exposed to radiant energy.

Much is known about the chemistry and chemical reactions of photochromic materials. It is known, for example, that the photochromatic reaction of certain materials can be reversed; that is, from transparent to colored and vice versa. Many publications and patents have reported the use of photochromic materials to enter information on the CD. When entering information on a CD, initially the photochromic material is opaque, and therefore absorbs the radiation with which the information is introduced and converted to a transparent form or is eliminated with thermal energy. However, in none of these references- the advantage of using these photochromic materials in reverse has been recognized. That is, there is no teaching or suggestion that low energy radiation (ie, reading frequency- and typical energies) could be used to make the data stored on the CD can not be read-, by using the reverse chemical reaction of photochromatic materials.

Summary of the Invention In this invention it has been discovered that the data contained in an optically readable device can become non-readable by exposing the achromatic state to low energy radiation sources. (transparent) of the photochromatic materials, for example, lasers or light-emitting diodes, to obtain a colored state of the. same- .. In. cor-sequence, in. this specification describes a novel optically readable device, for example a CD, which contains a substrate on which a film containing a photochromic material has been partially or totally disposed. The film is changed from its achromatic state to a colored state by exposing it to a light with a suitable wavelength, that is, the wavelength of the reading radiation. In this way, the radiation converts the readable CD into a non-readable CD. The photochemical reaction can not be reversed easily and, in this way, becomes permanent.

In its broadest sense, the present invention relates to an optically readable device, such as a CD, which includes a) the data contained in said device, and b) means for rendering said data unusable after at least one reading optical of said data. The data can be audio, visual, computer programs and the like. As will be explained later, the means to make the data unreadable can be chemical, electrical or a combination of both. After the reading radiation reads one or more times the data, the chemical means, for example, will make the data can not be read or used.

Thus, a method for making a CD adapted to be used a limited number of times is described, which includes the steps of providing a transparent substrate, providing depressions and projections (non-etched parts) in the substrate, placing a layer of photosensitive material within the substrate, said photosensitive material having a predetermined thickness so as to allow adequate focusing of the laser beam of a CD device, the photosensitive material being substantially transparent and being adapted to darken as the laser beam is propagated by the photosensitive material, the layer of photosensitive material is adapted to darken after a certain number of times the CD has been reproduced, so that proper reading of the CD is prevented and a layer of the reflective coating is placed over the depressions and protrusions of the substrate. In an alternative embodiment, the photosensitive material is only placed on a portion, or several portions of the CD, which means that only selected areas of the CD can not be read after a predetermined number of readings.

There is further described a limited use CD that includes a layer of a transparent substrate having an upper face and a lower face, the transparent substrate layer having a number of predetermined depressed and highlighted portions, a layer of reflective metal over the depressions and protrusions of the transparent substrate, a protective layer covering the reflective metal layer, plus a layer of photosensitive / photochromic material placed on a substrate, the photosensitive / photochromic material being transparent when placed on the CD and adapted to darken at the time of propagating the light from a light source of a CD device through the photosensitive / photochromatic material, and wherein the photosensitive / photochromatic material is darkened to prevent proper reading of the CD.

The photochromic material can be selected from a group consisting of: a) an amphipathic derivative of azobenzene, indigo or thioindigo; silver halide crystals; Spiropyrans and their derivatives; d) macrocyclic azaannulene dyes; e) polymethine dyes; f) anthraquinone dyes; g) azulene dyes; h) azo dyes; i) methylene blue j) Isol red k) antimony seleniate 1) Tellurium oxide Fluorinated compounds n) at least one element chosen from Te, Pb, Au, Sn, As, Bi and Carbon, and an iodine compound o) a rhodamine dye p) an aggregate J q) an aggregate H r) a metal azide s) a compound generating free radicals; Y t) a liquid crystal A method for making a CD of limited use by a transparent substrate is also described, placing a first layer of material on the transparent substrate, said first layer of material having portions adapted to reflect the light. emitted by a light source of a CD device, and covering a predetermined portion of the transparent substrate with a photosensitive material that is transparent when placed on the CD and that is adapted to darken as the light emitted by the light source of the CD device propagates through a photosensitive material, and where the photosensitive material darkens to prevent proper reading of the CD.

In addition to the aforementioned characteristics, the objects and advantages of the present invention will be obvious upon reading the following description.

Brief Description of the Drawings The novel features and advantages of the present invention, in addition to those mentioned above, will be obvious to those of ordinary skill in the art, upon reading the following detailed description together with the appended drawings, in which like reference characters refer to similar parts. , and in which: Figure 1 is a partial cross section of a conventional compact disc, in which the layers and components of the disc are illustrated; Figure 2 is a graphic illustration of an embodiment of the invention; Figure 3 is a graphic illustration of a second embodiment of the invention; Y Figure 4 is a schematic diagram of an embodiment of an electrical circuit that can be used to practice the present invention.

Detailed Description of the Preferred Embodiments It is not intended that the preferred system described herein be exhaustive or that it limit the invention to the exact forms described. They have been chosen and described to explain the principles of the invention and the application of the method to put it into practice, so that those having knowledge of the subject can put the invention into practice.

The present invention can be applied in the same way to the following: 1) to the traditional technology of compact discs for storing audio data, video data or software; 2) DVD compact discs (Digital Video Disc); Y 3) any other optically readable equivalent technology. The following detailed description describes the limited use compact disc technology of the present invention with respect to the standards of traditional audio compact discs.

Figure 1 illustrates the layers that are on a traditional audio compact disc. A traditional compact disc has a transparent substrate layer (eg, polycarbonate) 10, a coating of a reflective layer a (eg, aluminum) 12 on the substrate 10, a protective layer 14, and a label 16. The disc compact has "depressions" 18 and "protrusions" 20 in a predetermined pattern on the substrate 10. The pattern of the depressions 18 and of the projections 20 of the compact disk includes the data contained in the compact disc.

A compact disk contains a long succession of depressions 18 helically recorded on the disk. Each depression 18 is approximately 0.5 microns wide, and 0.83 microns to 3.56 microns long. The areas that lie between the depressions are the areas called projections 20. As discussed, the pattern of the depressions 18 and the projections 20 represents the data of the disk. In audio compact discs, depressions and projections represent values of an analog audio signal that can be reconstructed by a compact disc player by reading the digitized information in the form of depressions and outlets.

The audio data is converted to digital form to be placed on a compact disc, through the following steps: 1) sampling of the audio signal at a predetermined speed; 2) quantification of the samples (assigning each sample a discrete value); 3) encoding the data by pulse coding modulation (PCM); Y 4) Transfer of PCM audio data to a substrate, in the form of depressions and outgoing.

The depressions 18 and the projections 20 are covered by a layer of reflective metal 12, such as aluminum. As is well known in the industry, when reproduced, a light source (for example, a diode laser) emitted by a compact disc device shines in depressions 18 and in projections 20. When the light emitted by the light source incident on a projection 20, the light is reflected back to a photodetector. When the light hits a depression 18, the photodetector will not receive any signal or receive a weak signal. Accordingly, the photodetector receives a series of light pulses corresponding to the depressions 18 and the projections 20 on the compact disc. An analogue to digital data converter of the compact disc device converts the series of pulses back to binary coding and then to decimal values. The analog audio signal can be reconstructed from these data.

The exact specifications and rules of an audio compact disc can be found in the "Red Book". The "Red Book" and other "Books" discussed below are international industry standards that allow CD manufacturers to make CDs that can be read on the right CD player. These books are well known to those who have contact with the CD industry. The Red Book describes the physical properties of the audio compact disc and the coding of digital audio data. Includes the following information: a) audio specifications for a 16-bit PCM; b) disk specifications (for example, transparent substrate with a refractive index of 1.55), including physical parameters (for example, the recording area is 46 mm-117 mm); c) the optical reproductive needle and the parameters, including the laser wavelength (ie 780nm), the numerical aperture, the size of the depressions and the distance between tracks; d) deviations and proportion of errors in the blocks; e) modulation and error correction system; f) subcode channels; Y g) rotational speed (for example, 1.2-1.4 m / sec.).

There is also a Yellow Book for CD-ROM standards, a Green Book for CD-Interactive standards, an Orange Book for recordable CDs, and a Blue Book for Stereophonic Music CDs. A set of standards for the Digital Versatile Disc or DVD has also been created, however, the industry has not officially accepted those standards.

The depressions that the CDs have are very small. Consequently, the light emitted by the light source should focus on a very small disk space. As the light emitted by the light source is introduced into the substrate 10, the light is refracted from entering the substrate, which has a Refractive Index of about 1.55. When the speed of light decreases, the beam is refracted and focusing takes place. The size of the light spot on the surface of the disc has a diameter of approximately 800 micrometers, but is focused at approximately 1 micrometer on the surface of the depression. The typical laser length of a CD player, in the air, is 780 nanometers, while inside the polycarbonate substrate, which has a Refractive Index of 1.55, the laser wavelength is approximately 500 nanometers. On DVDs, the laser wavelength is 650 and 635 nanometers. The shorter wavelengths for DVDs are more suitable for reading the smaller and more densely stored depressions.

The present invention offers the way to configure a compact disc so that it is limited to a predetermined number of uses. The present invention can be implemented with various methods and with different compact disk technologies. Although the specification has been written with respect to a traditional audio CD technology, it is emphasized that the present invention is not limited to such means.

The present invention also provides an electrical method for configuring compact discs, or a section of the disc, so that the consumer is limited to a predetermined number of uses. The compact disc is configured in such a way that after a certain number of readings an electrical element of the compact disc of the present invention is activated so that it limits and blocks the penetration of the light emitted by the light source. This blocking or interruption of the light prevents the reader or CD player from reading it properly, thus making the disc no longer usable or certain sections of it can not be read. In a further embodiment, the electrical element modifies the control data that is encoded therein, such that the modified control data causes the compact disc reading device to be unable to read one or more tracks.

The use of chemical or electrical means to make all or a portion of the data stored in the optical device unreadable, after having been read a certain number of times, forms the basis of this invention. This goal is achieved by adulterating at least a critical number of depressions and / or projections to corrupt the data to the extent that the output is of an unacceptable quality. The level of adulteration needed to make the output unacceptable, will be different for each CD format.

Figures 2 and 3 illustrate the graphic representation of the layers of a compact disc according to two (2) embodiments of the present invention. The compact disk of the present invention (for traditional audio discs) should preferably be constituted by a transparent substrate layer 10 having an upper face and a lower face, wherein the transparent substrate layer 10 has a certain number of portions with depressions and outgoing; a reflecting metal layer 12 on the depressions 18 and the projections 20 of the transparent substrate 10; a protective layer 14 covering the reflecting metal layer 12; a label 16 on the protective layer and a layer of photochromic material 30 whose thickness, concentration and / or reactivity are determined by the energy and wavelength of the reading radiation and by the number of readings allowed. First, it is transparent, but is then adapted to darken as the light emitted by the light source of the CD player device propagates through the photochromic material 30 and when reflected.The wavelength of the emitting and their reflection are not the same thing This darkening of the photochromic material 30 eventually prevents proper reading of the CD.

Depending on the properties of the material used, the layer of photochromic material 30 could be placed between the upper portion 32 (see Figure 1) of the substrate 10 and the reflective metal layer 12 (for traditional CDs), or the layer of photochromic material 30 could be placed on said lower face 34 (see Figure 1) of the transparent substrate 10. The photochromic material could also be placed at both sites. An alternative embodiment of the invention consists in placing the photochromic material inside the substrate 10 during the formulation of the resin layer of the substrate.

Additionally, the layer of photochromic material 30 can be placed on various portions of the CD. The material 30 can be placed on the entire surface of the substrate 10, or only on certain selected portions of the surface. For example, material 30 can be placed on the CD entry portion, the data portion, or the exit portion. The portion of the surface of the substrate 10 to be covered will depend on the existing cost limitations and the data portions to be blocked.

The photochromic material 30 preferably used must be a photosensitive material that at least partially becomes irreversibly dark or fatigued when exposed to the read radiation of the compact disc player. It should be understood that the reading radiation includes the initial radiation thereof after it hits the reflective layer.

The photochromic material 30 is adapted so that the material 30 darkens after a predetermined number of exposures (exposure time) to the reading radiation. For example, if the photochromic material 30 is placed on the underside 34 of the substrate 10 on something other than a DVD, the material should react to light with a wavelength of 780 nanometers, although it will react to 500 nanometers approximately if it will be placed on the upper face 32 of the substrate 10. Accordingly, the CD can only be reproduced a predetermined number of times before the layer of the photochromic material 30 darkens and prevents proper reading of the CD.

The photochromic material 30 must be adapted to adhere to the substrate 10, and it must have an adequate refractive index to allow correct focusing of the light source 22 on the desired portion of the CD. Accordingly, if the material is placed in the lower face portion 34 of the substrate 10, it is preferable that the Refractive Index of the material 30, when it is tiansparent, is close to 1.0.

The Photochromic Material The basic concept of this invention is that the optically readable medium (ie, the CD) has one or more materials incorporated which, when exposed one or more times at the reading wavelength, become a form that prevents The disc can not be read effectively. Currently, the industry standard for non-DVD CD players is an aluminum gallium arsenide semiconductor (AlGaAs) laser with a power of 0.5 mW and a wavelength of 780 nm. As mentioned above, the DVDs will use a laser wavelength of 650 and 635 nm plus other different parameters (for example, the distance between tracks). It should be understood that the basic concept of the invention is not limited to the present standard, however, the detailed description of the invention will be directed to the currently accepted technology.

A further basic concept of the invention relates to the requirement that the photochromic material, once altered by the reading radiation, substantially remains in that altered state so as to prevent any further reading of the optical device. Yet another concept of the invention relates to the placement of the photochromic material, in which, in one embodiment, the photochromic material is placed exactly on top of the reflective material in the form of a layer or film. In a second embodiment, the photochromic material is placed on the outside of the substrate, while in a third embodiment, the photochromic material is dispersed, continuously or discontinuously, within the substrate.

Any technician skilled in the art will appreciate that depending on the refractive index of the substrate, the reading radiation wave will change. Thus, if the photochromic material is placed adjacently to the reflective layer, its absorption spectrum should correspond, at that point, to the wavelength of the reading radiation. Conversely, if the photochromic material is placed on the outside of the substrate, the maximum absorption spectrum of the substrate should be approximately the frequency of the laser or reading diode.

In general terms, the photochromic material will be a photoreactive material that is converted from a substantially transparent form to another that interferes with the reading radiation, to make at least a portion of the data contained in the optical disc can not be read or not can be used Currently, several photochemical transformation schemes that can be obtained in the market are known. Although not always, photoreactive systems generally require an amplification phase where a catalyst or an initiator is produced, or already exists, for a chemical reaction to take place. It is feasible to induce a breakage of the dye bond, that is, a transformation in various frequencies of the electromagnetic spectrum, including the closest infrared region.

The photochromic compound can, for example, be based on this cis-trans isomerization of an amphipathic derivative of azobenzene, the Indigo or the thioindigo having a long chain substituent. Preferably, the amphipathic compound is a monomolecular film adjacent to the reflecting layer of the optical device. "More specifically, the azobenzene derivative is 4-mono-stearoylazobenzene, the indigo derivative is N, N'-distearoylindigo and the thioindigo derivative. is 5'-octadecyl-5-t-butylthioindigo, and / or 5-octadecyl-l, 8-naphthylthioindigo.

In one embodiment, the photochromic material is composed such that it has a transmittance of at least 40% and a hand absorbency of 20% at the wavelength of the reading radiation at the material placement point photochromatic After being exposed to the reading radiation, the photochromic material shows a lower transmittance and a higher absorption of the reading radiation. The level of transmittance and absorbency can be modified to control the number of "readings" available on the CD.

In another embodiment, the photochromic material can change the reflectance to the reading radiation. Initially, the photochromic material will have a reflectance of no more than 20%, but after one or more exposures to the reading radiation its reflectance will be at least 40%.

In the case in which the photochromic material is placed in the form of a film or layer, the thickness of the layer can fluctuate between 5 and 400 nm, which will depend on the number of reproductions that are desired and the reactivity of the photochromic material. More specifically, the thickness of the photochromic layer can fluctuate between 10 and 200 nm.

In yet another means to achieve the objective of this invention, the photochromic material can undergo a phase change to make at least a critical portion of the CD unreadable. More specifically, the reading radiation converts the photochromic or photoreactive material from crystalline to non-crystalline or vice versa. For example, while in crystalline form, the photoreactive material allows the metallized layer to reflect the laser light, and while it is in a non-crystalline form, absorbs or reflects the laser beam, thereby causing the CD, or the portion of the CD that is in contact with the photochromic material, can not be read.

In any of the modes of operation (ie, change of absorbency or change of reflectance) the photoreactive layer will demonstrate its resistance, reliability and longevity against heat, humidity and short periods of visible light for a reasonable period of time, say a year, for a limited life CD.

Another means to achieve the goal of this invention is to employ a thermal deformation technology. In this approach, an initially transparent photoactive material absorbs the reading radiation and triggers a chemical reaction that generates sufficient heat to deform the depressions and protrusions and / or the substrate to the extent that the recorded data is no longer useful. Although the energy of the currently available CD player (about 0.5 mW at about 780 nm) is insufficient to cause such deformations, the photoreactive material can be designed in such a way that the reading radiation initiates a chemical reaction of sufficient exothermic energy to make that the CD can not be read after a desired number of readings. Photoinitiators and sensitizers known in the art can be used together with known components that have an exothermic reaction, in order to achieve the desired result.

One method to obtain a useful photosensitive material is to employ a photochromic material having silver halide crystals with dimensions in the range of 50 to 800 angstroms. The silver halide crystals are doped with copper ions and / or another sensitizer selected from mild reducing agents, thioethers, or sulfur-containing ions, which are treated with an agent to accelerate the forward reaction and control the reverse reaction of opaque to transparent. Representative accelerators include ions of the cobalt, chromium, manganese, magnesium and rare earth metals such as cerium, samarium and europium. The agent for controlling the reverse reaction is preferably phosphoric acid.

An example of a type of photo-reactive or photochromatic material that can be altered with a low-energy laser or a light-emitting diode (one millivolt or less), are spiropyrans and their derivatives. A typical representative material of these is 6'-nitro-1,3,3, trimethylindolinobenzospiropyran; 1,3,3-trimethylindolenaptospiropyran and its derivatives, such as, for example, N-methylacridinonaphtho-pyran, diantrone, dixanthylene, xantilidenantrone and its derivatives.

A light-sensitive film-forming solution is obtained by preparing a diluted solution of polymer (e.g., polymethylmethacrylate) in a solvent compatible with the photochromic material. -The solution thus prepared is saturated with the photochromic material to obtain very thin films with a high concentration of photochromatics. A typical solution used for the present invention is prepared by dissolving 240 mg of polymethylmethacrylate in 6 ml of acetonitrile, and adding to it 100 mg of 1,3,3-trimethylindolino benzospyran. The solution is then used to coat a polymeric substrate by conventional methods, for example by rotating the substrate, immersing it in the solution, spraying it, or by similar processes.

Next, the colorless photoreactive layer is exposed to a laser pulse of 300 nano-seconds, with a frequency of 780 nm and a power of approximately 0.5 mw. In this way a series of 3 micrometer spots is obtained. It should be understood that the photochromic material can be chemically modified to absorb and transform certain frequency and energy of a given laser light.

Another method to achieve the objective of the present invention is to include known organic dyes in the transparent substrate, to achieve that the optical transparency of the substrate is modified. Some examples of dyes include: macrocyclic azaannulene dyes such as phthalocyanine dyes, naphthalocyanine dyes, porphyrin dyes and the like; polymethine dyes, such as cyanine dyes, merocyanine dyes, styryl dyes, escuiarilium dyes and the like; and in addition, anthraquinone dyes, azulenlo dyes, azo dyes, and the like. These dyes absorb the reading radiation and generate heat. As a result, the organic dye melts, vaporizes, sublimates, deforms, or modifies the qualities of the depressions and protrusions, so that they can no longer be read. This method is somewhat limited if you do not have a thermal initiator, because the typical power of the reading radiation is insufficient to cause the necessary deformations after making two (2) or three (3) CD readings.

Another additional method to achieve the aim of the present invention is to employ a photosensitive photodecoloring material. In this embodiment, a section of the disk that encodes reading parameters is coated with an opaque tint, thus initially preventing the reading of this information with the CD player. Aunts several exposures to reading radiation, the discoloration of the dye allows the CD player to read the information previously covered. The newly exposed data instructs the CD player so that it can not obtain more information from the disc.

Photodecolouration or photolysis can be achieved by combining known dyes with various sensitizers or accelerators, such as allylthiourea. In the photo-discoloration process the dye is oxidized or reduced as a result of absorbing radiation. For example, methylene blue, which can be sensitized with reducing agents such as thiosinamide, undergoes photoreduction and gives rise to colorless leuco forms, whereas polymethine dyes are oxidized to colorless forms. Certain types of dyes, such as Isol Red (available from Allied Chemical Corp.) can easily be photo-decolorized by adding an accelerator. There are numerous photo-decolorising dyes known in the field and are useful for the practice of the invention.

In general, regardless of the particular methods that are used to alter the spectral absorbency, the utility dyes are chosen for their respective compatibilities with the binders, for their high absorbance at the respective wavelength of the respective reading beam and for their ability to make the CD unusable.

Another aspect of the present invention relates to changes in reflectance. As a kind of photochromic materials, compounds such as antimony selenide (S2Se3) and tellurium oxide (TeOx) can be sensitized at the reading frequency to transform from being substantially transparent to reflective. Other materials that can undergo modification of the reflectance by absorption of the reading radiation, include fluoride compounds, such as BiF3, MgF2, PbF2, LiF, CeF3, AgF, CaF2, CrF ?, CrF3 and carbon fluoride. The film thickness of these compounds can be from 300 Á to 5,000 Á. A change in reflectance can also be achieved by employing a film including a) a substance that can undergo an optical change by absorbing the reading radiation, such as Te, Pb, Au, Sn, As, Bi and carbon; b) a matrix of iodine compounds, wherein the iodinated compound is at least one compound selected from copper iodide, cesium iodide, tin iodide, antimony iodide, zirconium iodide, silver iodide, lead iodide and Thallium iodide. As with the opaque method for the purpose of this invention, the increase of reflective in the photoreactive layer will make the CD impossible to read.

Another example of a photoreactive material useful in the present invention is a rhodamine dye that dissolves into a non-polar polymer to form a colorless film (leuco form), which, upon exposure to the activating light, acquires a permanent color without need of any fixing process. The rhodamine photoreactive materials, as they currently exist, are more suitable for a frequency reading of approximately 2350-3150 Á. The chemical modifications that are made in the rhodamine dye can displace the effective wavelength to approximately 800 nm.

The photoreactive material may also include at least two (2) types of organic dyes, which respectively are transformed into aggregates by association. As is well known in this field, organic dyes can form an aggregate of several dye molecules under certain conditions. In some cases the aggregate has physical properties, such as stability, spectral characteristics and similar, which are totally different from the original dyes. Aggregates useful in this invention include a dimer, an aggregate J, an aggregate H, and composite materials thereof. The aggregates J are the preferred ones. The term "aggregate J" as used herein, is used to refer to an aggregate of a plurality of dye molecules, not including any change in chemical structure, that has a more visible range of visible absorption spectrum than dyes components, and whose absorption spectrum shifts to longer wavelengths.

The dyes that may form aggregates J include the photochromic dyes. Typical photochromic dyes include spiropyrans, azobenzenes, fulgidos, indigos, thioindigos, tiarilmethanes and the like. In this invention, spiropyrans are preferred. The aggregates J are most useful when the reading radiation is in the range of 500-300 nm.

A photoreactive material of great interest and utility for the present invention is a metal azide. The metal azide acts as a substance that simplifies energy. The metal azide used alone or in combination with a dye that absorbs energy can be activated with a pulse of low energy laser light and thus alter the reading ability of the CD. For example, the reading radiation initiates the reaction of the metal azide and the substrate acquires charge or its refractive index is modified. The copper, lead and silver azides are the most suitable, since they react in a very exothermic form and nevertheless can easily be incorporated into the optical device. The metal azide can be applied to the substrate in a binder of polymeric material, such as gelatin, or it can be applied directly by vapor deposition. The layer of photosensitive material generally has a thickness of 0.5 to 5 microns. The erythrosine, erythrosin B, sudan III, rhodamine 6 G and rose bengal tints are all suitable for use with metallic azide.

The technology developed for the laser printing industry is also applicable in this invention. For example, the substrate can be coated with a chromogenic heat-sensitive layer containing a basic dye and an organic developer. Next, a second layer containing an absorbent in the near infrared (optionally including an azide) is placed adjacent to the color layer. The reading radiation causes heat to be generated in the absorbent layer, which in turn causes the activation of the layer that generates the color.

In another aspect of the present invention, the photoreactive material can include a compound that generates free radicals. The free radical generating compound can be activated directly with the reading radiation or as a result of the heat generated by an absorbent dye. The generated free radicals promote various reactions, and as a result the CD is illegible (for example, discoloration). More specifically, the free radical generating compound may be selected from azo compounds, diacryl peroxides, dialkyl peroxides, hydroperoxides, sulfur compounds, compounds. carbonyl, halogenated compounds, reducing dyes, organometallic compounds and persulfates.

Another interesting method for producing a limited reading CD is to use liquid crystals. In this embodiment, the photoreactive layer includes at least one type of liquid crystal that can change state, by agglomeration or rearrangement, by absorbing the reading radiation. The liquid crystal can also be combined with dyes that absorb radiation to facilitate the change of radiation transmission.

It is known that liquid crystals dispersed in polymers (PDLCs) can be used to moderate infrared light. This method may also be useful for the present invention. Very different polymers can be used to retain the liquid crystal, for example, polyvinylpyrrolidone (PVP). The PDLCs are prepared by dispersing the nematic material E7 in the polymeric binder PVP. Then the PDLC is placed between two substrates and integrated into the CD.

Another approach of the invention relates to a photochromic material containing a copolymer of a prepolymer derived from a spirobenzothiopyran and from a liquid crystal prepolymer. The spirobenzothiopyran prepolymer is generally employed in an amount of 1-50 parts by weight, based on 100 parts by weight of the liquid crystal prepolymer.

According to the invention, the photoreactive material can also be a high liquid crystalline polymer, having side chains and a coloring matter having a reading light absorbing property. The liquid crystal polymer has side chain groups provided with molecular rotation power or has the power to change state, such as agglomeration or rearrangement. When this material is irradiated by the reading laser, an affinity and association are induced between the polymer compound and the dyeing compound, or a dissociation and separation of the dyeing compound from the polymer compound, due to the differences between the chemical and physical characteristics , as the transition point of the glass. This mechanism changes the optical property from substantially transparent to opaque.

Manufacturing Techniques There are several important factors that must be taken into account when manufacturing optical devices according to the invention. The first is precision. The provider of limited reading CDs should be assured that valuable data is disabled after a certain number of readings. Depending on the given approach and the photoreactive material that is chosen, a technician with knowledge of the art will be able to easily determine the exact parameters (i.e., the thickness of the film, the sensitivity and the like) that are required to achieve the desired number of images. readings before the disk can no longer be used. The second important issue is the speed of manufacture. Taking into account the fact that the CDs according to this invention will be distributed without charges, the cost to produce them should be minimized. This requires a process such as a high-speed assembly line. In addition, the system must be able to quickly switch from the production of one disc to the production of another, due to the large number of artists and software and how quickly the tastes of modern consumers change. This means that most of the equipment for the manufacturing process must be common to each CD that you plan to produce. An invaluable aspect of the invention resides in the ability to produce limited reading CDs without having to resort to expensive, inefficient and special manufacturing processes.

The present invention can be included as any of the known processes for making CD's, such as the standard technique of injection-molding, direct mastering techniques for reading and recording, the technique of direct mastering on metal, light-curing, mastering in glass and the like.

When the photoreactive material is placed adjacent to the reflective layer or on the upper surface of the substrate, a rotation coating method is generally preferred in order to easily form the film, and for economy. With this approach, the photoreactive / photochromatic material or the photoreactive system is dissolved with a suitable solvent that does not damage the substrate used or the photochromic material. For example, in the case of a polycarbonate substrate, suitable solvents include aliphatic or alicyclic hydrocarbons such as hexane, heptane, ophane, cyclohexane, and the like.; non-polar ether solvents such as diethyl ether, dibutyl ether and the like; polar alcohol solvents such as methyl alcohol, ethyl alcohol, allyl alcohol, cellosolve, and the like. The mixture of photosensitive materials / solvents may also include binders such as resin and gelatin.

The photoreactive material can also be applied to the structure of the CD by dip coating, spray coating, roll coating and the like.

In an alternative embodiment, the photosensitive material is dispersed within the substrate. In this approach, the photosensitized material may or may not be copolymerized with the resin of the substrate. Although the need to implement an additional coating step (ie, spin coating) is eliminated, the incorporation of the photosensitive material into the resin of the substrate must strictly adhere to the processing parameters, such as the thermal degradation of the photosensitive material. , and manufacturing techniques.

Electrical Method In another embodiment of the present invention, an electrical circuit may be used to detect the read radiation and to initiate the process of rendering a predetermined portion of the CD unreadable. Figure 4 illustrates an example of a schematic diagram of an embodiment of an electrical circuit that can be used to carry out the functions of the present invention.

Due to the existing manufacturing techniques, the small circuit of Figure 4 can be soldered on a very small chip that can be connected to the CD substrate. In a preferred embodiment, the circuit is connected to the surface of the polycarbonate substrate. The circuit should be connected in such a way that its placement does not block the exposure of the laser to the information contained in the depressions and on the projections of the CD (for example, outside or inside the recording area). Although the circuit should be placed so that it does not interfere with CD playback, the photodiode should be placed on the substrate in a location that allows it to detect the reading radiation from the CD laser each time the CD is played.

In the embodiment of Figure 4, a photodiode 40 detects the radiation coming from the laser at the moment when the CD reading starts. The photodiode -40 detects the laser radiation and converts the energy into an electrical signal. The photodiode 40 is adapted to detect the output of the standard laser, whose specifications we discussed above. This electrical signal is preferably amplified and fed to an input of a counter circuit 42. The counter 42, initially set to zero values, keeps track of the number of times the CD is read (ie, played or played) . After a predetermined count (i.e., CD reproductions) the output of the counter 42 is used to initiate a means to interfere with the reading radiation 44, so as to make at least a portion of the data contained in the optical disk They can not be read or used. For example, a predetermined number of the outputs of the counter 42 can be connected to the inputs of a gate Y 46, whose output is used to initiate the means to interfere with the read radiation 44.

The means for interfering with the reading radiation 44 of the CD light may be a layer of liquid crystal interspersed between the other layers of the CD. The liquid crystal layer will change from a transparent light to a state of light diffusion when applied to an electric field (for example, when initiated by the counter 42 of Figure 4). In the ON state, the reading laser light is diffused by the orientation of the liquid crystals (ie the liquid crystals are opaque). In the OFF state (that is, once the electric field is applied), the crystals are reoriented throughout the field, causing the liquid crystal to transmit light. The orientation of the liquid crystals within the substrate is directed in accordance with well-known principles. Transparent electrodes, such as those known in the art, can be used to conduct electrical signals to liquid crystals without interfering with the reading light. In another embodiment, the means used to interfere with the reading radiation 44 of the laser, is a predetermined transparent chemical layer, which is preferably deposited on the layer of the polycarbonate substrate, which becomes opaque when stimulated by an electrical signal. In the preferred embodiment, the circuit of Figure 4 is energized by a battery 50. In another embodiment, the means used to interfere with the laser reading radiation will be a light source of about 500 nm located in the circuit .

Industrial Applicability The software and entertainment industries are constantly looking for techniques to promote their products to the consumer. Although the tactic of offering a "free sample" is very useful to sellers of soap and detergents, has not had acceptance in the CD industry. Now this invention provides a means for the software industry and videos to allow consumers to try a limited number of times their articles to induce them to buy a fully usable version.

Once a preferred embodiment of the invention is shown and described, those of skill in the art will realize that many variations and modifications can be made to practice the disclosed invention, and it will still be within the spirit of the claimed invention. In this way, many of the aforementioned elements may be modified or replaced by other different elements that will give the same result and remain within the scope of the claimed invention. Accordingly, it is intended to limit the invention only as indicated by the scope of the claims.

Claims (28)

E IS CLAIMED IS:
1. An optically readable device that includes: a) the data contained in said device; Y b) means for rendering said data unusable after an optical reading, at least, of said data.
2. A method for manufacturing a compact disc (CD) adapted to be used a limited number of times, which includes the following steps: (a) provide a transparent substrate; (b) providing depressions and projections on said substrate; (c) placing a layer of photochromic material on a predetermined portion of said substrate, said photochromic material having a predetermined thickness to allow adequate focusing of the laser beam of a CD device, said photochromic material being initially substantially transparent and being adapted to be less transparent when said laser beam is propagated through said photochromic material, said layer of photochromic material being adapted to make it impossible to read a critical percentage of the data contained in said CD after it has been reproduced a predetermined number of times; Y (d) placing a layer of reflective coating on said depressions and projections of said substrate.
3. The method according to claim 2, wherein said layer of photochromic material is placed in the lower portion of said substrate.
4. The method according to claim 2, wherein said layer of photochromic material is placed on an entrance portion of said CD.
5. The method according to claim 2, wherein said layer of photochromic material is placed substantially on a portion of the data storage of said CD.
6. The method according to claim 2, wherein said photochromic material is selected from the group consisting of: (a) an amphipathic derivative of azobenzene, Indigo or thioindigo; (b) silver halide crystals; (c) Spiropyrans and their derivatives; (d) macrocyclic azaannulene dyes; (e) polymethine dyes; (f) anthraquinone dyes; (g) azulene dyes; (h) azo dyes; (i) methylene blue (j) Isol red (k) Antimony selenite (1) tellurium oxide (m) fluorinated compounds (n) at least one element chosen from Te, Pb, Au, Sn, As, Bi and Carbon, and an iodine compound (o) a rhodamine dye (p) an aggregate J (q) an aggregate H (r) a metal azide (s) a free radical generating compound; Y (t) a liquid crystal
7. The method according to claim 6, wherein said photochromic material comprises a compound selected from the group consisting of 4-monoesfearoi 1 azobenzene, N, N'-di stearoi 1 indigo, 5-octadecyl-5'-butylthioindigo, 5-octadecyl -l, 8-naphthylthioindigo, 6initro-l, 3, 3-trimet ilindolinobenzosprio-pyrano, 1, 3, 3 trimetilindonaftospriopyrano, phthalocyanine dyes, naphthalocycitan dyes, porphyrin dyes, cyanine dyes, acrocyanin dyes, styryl dyes , escuiaril dyes, anthraquinone dyes, azo dyes, BiF3, MgF2, PbF2, LiF, CeF3, AgF, CaF2, CrF2, CrF3, carbon fluoride, erythrosine, erythrosin B, sudan III, rose bengal and peroxides.
8. The method according to claim 2, wherein said layer of photochromic material is placed on an exit portion of said CD.
9. The method according to claim 2, wherein said photochromic material becomes less transparent upon receiving radiation at a wavelength of about 780 nm.
10. 10. A CD manufactured according to the process of claim 2.
11. 11. A method for manufacturing a limited use compact disc (CD); said CD being formed of a transparent substrate, which includes the following steps: a) supply a CD; Y b) placing a photochromic material on a predetermined portion of said transparent substrate, said photochromic material being substantially transparent prior to exposure to the reading radiation.
12. The method according to claim 10, wherein said photochromic material is selected from the group consisting of: a) an amphipathic derivative of azobenzene, Indigo or thioindigo; b) silver halide crystals; c) Spiropyrans and their derivatives; d) macrocyclic azaannulene dyes; } e) polymethine dyes; f) anthraquinone dyes; g) azulenium dyes; h) azo dyes; i) methylene blue; j) red isol; k) antimony seleniate; 1) tellurium oxide; m) fluorinated compounds; n) at least one element chosen from Te, Pb, Au, Sn, As, Bi and Carbon, and an iodine compound; o) a rhodamine dye; P) an aggregate J; q) an aggregate H; r) a metal azide; s) a compound generating free radicals; Y t) a liquid crystal.
13. The method according to claim 12, wherein said photochromic material includes 4-mono-stearoylazobenzene, N, N'-distearoylindigo, 5-octadecyl-5'-butylthioindigo, 5-octadecyl-l, 8-naphthylioindigo, 6'nitro-l , 3, 3 trimethyl-indolinobenzosprio-pyran, 1,3,3-trimethyl-indonaphthio-ppriopyran, phthalocyanine dyes, naphthalocyanine dyes, porphyrin dyes, cyanide dyes, mecrecian dyes, styryl dyes, escuiaril dyes, anthraquinone dyes, azo dyes, BiF3, MgF2, PbF2, LiF, CeF3, AgF, CaF2, CrF2, CrF3, carbon fluoride, erythrosine, erythrosin B, sudan III, rose bengal and peroxides.
14. The method according to claim 11, wherein said layer of photochromic material is placed on an upper outlet portion of said CD.
15. 15. The method according to claim 11, wherein said photochromic material is placed on a lower portion of said substrate;
16. 16, A CD manufactured according to the process of claim 11
17. 17. A limited use CD that includes: a) a transparent substrate layer having an upper and lower portion, and said transparent substrate layer having predetermined portions of depressions and projections; b) a layer of reflective material on said depressions and projections of said transparent substrate; c) a protective layer covering said reflective metallic layer; d) a layer of photochromic material placed on said substrate, said predetermined material being transparent when placed on said CD and adapted to be obscured when the light emitted by a light source of a CD device is propagated through said predetermined material, and wherein said predetermined material is obscured to prevent the correct reading of said CD.
18. 18. A limited use CD according to claim 17, wherein said layer of photochromic material is placed between said upper portion of said substrate and said reflective metallic layer.
19. A limited use CD according to claim 17, wherein said layer of predetermined material is placed in the lower part of said transparent substrate.
20. A limited use CD according to claim 17, wherein said CD is an audio disc, formatted according to the Red Book.
21. A limited use CD according to claim 17, wherein said reflective metal layer is selected from aluminum, silver and gold.
22. A limited use CD according to claim 17, wherein said layer of photochromic material is selected from the group consisting of: (a) an amphipathic derivative of azobenzene, Indigo or thioindigo; (b) silver halide crystals; (c) Spiropyrans and their derivatives; (d) macrocyclic azaannulene dyes; (e) polymethine dyes (f) anthraquinone dyes azulenium dyes (h azo dyes (methylene blue) (j red Isol (k antimony seleniate (1 tellurium oxide (m fluorinated compounds; (n at least one element chosen from Te, Pb, Au, Sn, As, Bi and Carbon, and an iodine compound; (or A rhodamine dye; (P An aggregate J (q An aggregate H (r A metal azide; (s A compound that generates free radicals; (t) A liquid crystal.
23. A method to make a compact disc of limited use: a) providing a transparent substrate; b) providing a first layer of material on said transparent substrate, and said first layer of material having portions adapted to reflect light from a light source of a compact disc device; c) covering a predetermined portion of the transparent substrate with a substantially transparent photochromic material when it is placed on said compact disc and adapted to darken when the light of said light source is propagated from the light source of said disc device through of said photochromic material, wherein said aforementioned photochromic material is darkened to prevent the correct reading of said compact disc.
24. 24. The method according to claim 23, wherein said first layer of material is a layer of reflecting metal.
25. 25. The method according to claim 23, wherein said first layer of material is an organic dye.
26. 26. The method according to claim 23, wherein said compact disc is a DVD disc.
27. 27. The method according to claim 26, wherein said photochromic material becomes less transparent upon receiving a radiation of wavelength close to 635 nm.
28. 28. The method according to claim 26, wherein said photochromic material becomes less transparent when irradiated at a wavelength of about 650 nm. A limited use CD that includes the following: (a) a CD having a transparent substrate layer; (b) an electrical circuit for detecting the reading radiation of a CD player / said electrical circuit being connected to a predetermined portion of the CD, said electrical circuit including: (i) a photodiode for detecting said read radiation; (ii) a counter circuit that is in electrical communication with said photodiode, said counter circuit increasing on said read radiation that is being detected by said photodiode; (iii) a means for interfering with said read radiation, said means being activated to interfere with said read radiation when said counter reaches a predetermined value. A limited use CD according to claim 29, wherein said means for interfering with said reading radiation is a liquid crystal layer adjacent to said transparent substrate layer, said liquid crystal layer being connected to electrodes, blocking said liquid crystal layer said read radiation when an electric field is applied to said electrodes when said counter reaches said predetermined value. A limited use CD according to claim 29, wherein said means for interfering with said read radiation is a light source of about 500 nm, said light source being connected to electrodes, said light source interfering with said Reading radiation when an electric field is applied to said electrodes when said counter reaches said predetermined value.