DE2636952A1 - Credit card data carrier - has information stored both in magnetic strip and by reflective particles which are read with IR scanner - Google Patents

Abstract

A credit card of laminated construction contains both magnetically recorded data and optical information to minimise the possibility of fraud. The card has two outer transparent layers (24, 26) of a plastic material, sandwiching an intermediate layer (22) that has a multi black light absorbing panel (28). The magnetic information tape (18) is bonded onto a transparent layer (30). Between this layer and the bonding strip (32) are a number of aluminium reflecting particles (20). Reading of information is by a conventional magnetic pick up and photo sensors operating with infra red light. The infra red passing between the aluminium particles is absorbed.

Description

description

Data carriers, in particular credit cards with magnetic tracks and processes for its production The invention relates to a data carrier, in particular Credit card, made of a plastic core layer, optionally on an or is provided with a transparent cover layer on both sides, which is on one A magnetic recording strip (magnetic strip, magnetic strip, Magnetic track) for magnetic data recording and playback a data carrier tape for its production and a method.

There are already different types of tape or card-shaped data carriers, In particular, credit cards have been proposed for the purpose of fraud with credit cards or the like. Most scams can be broken into classify the following two groups: 1. Alteration, multiplication, forgery of credit cards, 2. unauthorized use of valid, e.g. lost or stolen Credit cards.

Those resulting from the unauthorized use of credit cards Problems are to some extent due to the use of personal identification measures and insurance programs limiting the liability of the cardholder been.

Conversely, it has proven to be more difficult to take effective action against to meet the alteration and forgery of credit cards.

This problem can become increasingly serious as criminal elements are constantly working on improving counterfeiting procedures, e.g. of the peeling process "CBkimming"), which enable counterfeits to be found quickly and to manufacture at a low cost. Credit cards are constantly increasing Dimensions used in a wide variety of business transactions, e.g. for purchases in retail, when renting a car, to cover travel expenses, when withdrawing Cash and recently also for electronic transfer of amounts. With many These business transactions involve large sums of money, making an even greater one There is an incentive for criminal elements to forge credit cards in order to trade companies and the like to cheat. Since with an ever increasing spread of use With credit cards to be expected, it is obvious that there is an expedient solution of the problem mentioned must be found.

During the past few years, credit cards have been suggested that come with Invisible codes or the like. Are provided, which make it possible to counterfeit cards to be distinguished from real cards. For example, in U.S. Patent 3,468,046 there is a Credit card, which usually bears invisible labels, which readable under ultraviolet light. These designations also include the signature of the cardholder, e.g. signed by a business owner with the signature of the Customers can be compared on receipts or other accounting documents. Through this there is some certainty that it is the one presenting the card Person is the rightful owner. However, it would be for a forger Don't be difficult to imitate the signature or take fake cards Use of a suitable filter material and fluorescent signature surfaces to manufacture.

For secrecy purposes, the exploitation of was also reflected or through infrared radiation proposed. In U.S. Patent 3,829,660 is a computer-compatible information card described, the infrared radiation Has reflective surfaces, which by an adjacent imprint of infrared radiation absorbent printing ink are delimited, or in the case of infrared radiation permeable There are openings. The printing ink and the openings can be seen through removed thin upper and lower coatings of opaque material. the the latter US PS does not specifically deal with securing credit cards, but with the confidentiality of cards to be used in connection with computers. Applying the teaching of this US PS to credit cards would not result in a higher rate Degree of security, because in order to make a forgery, it would only be necessary be to separate the lamellas of the card from each other to form the labels To make printing ink or the openings recognizable.

In the newly issued US-PS RE 28 081 a credit card is disclosed, in which there is a pattern of infrared radiation transmitting openings. This opening or hole pattern is read, and the resulting, the Signals that identify the card are then used to check the account balance a central unit. This latter US-PS is therefore not restricted to the use of a Infrared radiation pattern directed to determine the authenticity of the card. Further the card is designed in such a way that it is easy for a forger to dismantle the card would be possible to reproduce the hole pattern.

The invention is based on the object of a data carrier, in particular To create a credit card or the like in which an imitation or forgery is almost is impossible and a method of making it.

The solution to this problem is with advantageous refinements in specified in the claims.

The disk has a set of optical data transmitted through the Radiant energy reflecting reflectors are formed so that the intensity and the properties of the reflected radiant energy on the credit card or Like. Uniquely assigned signal pattern forms that are extremely difficult to imitate or have it faked.

The credit card or the like created by the invention is high Counterfeit-proof dimensions. The magnetic data carrier is impermeable to visible radiation, but transparent to infrared radiation. In one embodiment of the innovation the reflectors or elements for modifying radiant energy are carried out Evaporated material is formed, the infrared radiation through the magnetic disk reflected through. Thus, the presence of a reflector is indicated by the reflection detected by infrared radiation through the magnetic data carrier.

Because of the opacity of the magnetic data carrier, it is difficult to see the size and / or location of the reflective surfaces using To detect radiation. Furthermore, the credit card is provided with a protective layer, which consists, for example, of a printing ink which has a high percentage of opaque Pigments, e.g. of carbon, are placed under the reflective elements and different radiation wavelengths including the visible range does not let through. Since the reflective elements are hidden on both sides, it is very difficult to determine and reproduce their exact size and location. In the preferred embodiment, the reflective elements are vapor deposition made in vacuum. The items are extremely thin and with the magnetic disk and the main body the credit card permanently connected so that It is very difficult to size and position the items by sanding off the material the card core or by disassembling the card to determine without the recognizability the spatial relationship between the elements is lost or impaired The invention is illustrated in more detail below with reference to schematic Drawings of exemplary embodiments explained.

It shows: FIG. 1 the top view of a typical credit card or the like. which is provided according to the invention with a property serving to secure; Figure 2 is an exploded perspective view of the parts of the credit card according to Fig. 1; 3 shows a perspective illustration of a credit card according to the invention in connection with an optical-magnetic reader; Fig. 4 is a block diagram of a typical security system for use in conjunction with one of the present invention Credit card; FIG. 5 shows an illustration of the generated by the reading device according to FIG optical data signals; and FIG. 5a shows a representation similar to FIG. 5, for a modified embodiment of a credit card according to the invention applies.

The shown in Fig. 1 and 2, designated as a whole by 10, with a credit card provided for security purposes according to the invention may have embossed information, e.g.

the account number and the name of the cardholder, as indicated at 12 respectively. 14 is indicated. The embossed information can be better known with the help of reading devices Type read for embossed characters, and in a typical business transaction you would use them for printing receipt forms or the like. use.

Furthermore, the credit card comes with sets of optical and magnetic Dates placed within an area near the top of the map i.e. within area 16. In the preferred embodiment the credit card looks similar or the same as a credit card known type with a magnetic strip 18, and the magnetic data are located within an elongated, generally rectangular area 16. The magnetic Stripe can have several magnetic data tracks, to which a track 1 and belong to a track 2, which corresponds to the regulations of the standard ANSI X4.16-1973. Preferably, track 1 would contain the account number and identification information while track 2 would contain additional information that normally would cannot be rewritten. There may also be a track 3 containing the information which often occur when using the credit card for business transactions updated or changed.

This information can include, for example, the balance of the account, as well Information about the frequency of use and information used for data processing. Of course, it is not intended that the magnetic strip alone be used to secure it Serving property of the credit card according to the invention.

The property used for securing is at least partially through a set of optical data is formed within the area 16, to which several below the magnetic strip 18 lying elements 20 for modifying radiant energy belong. In the preferred embodiment, these elements are vapor-deposited Reflectors made of e.g. aluminum and incident radiant energy, in particular those in the infrared range, reflect. The presence or lack of reflectors is made using an optical described below Detector detected.

As shown in Fig. 2, the main body of the credit card is made up of three layers 22, 24 and 26 made of polyvinyl chloride or polyvinyl chloride acetate, which form a laminate are united. The middle one, commonly referred to as core or soul material Layer 22 preferably contains pigments and plasticizers and is matte Surface. The upper layer 24 and the lower layer 26 are as smooth, thin, clear layers are formed with the core material in a known manner are glued and can have colored surfaces and legible designations. Possibly. layers 24 and 26 could also be omitted from a credit card.

In the manufacture of the card, the core material 22 is used prior to manufacture of the laminate on the top or bottom with a shielding layer or a Coating material 28 is provided which is generally impermeable to radiant energy is. In the preferred embodiment, a screen printing process is used an ink with a high percentage of carbon black on the core material applied essentially in register with the data area 16 of FIG. 1, so the desired shielding effect is achieved. It has been shown that the vinyl black, from the Union Ink Company under the legally protected name "Opak" is put on the market, but the carbon compared to the normal concentration contains in about twice the concentration, meets the requirements. Of the Soot absorbs a high percentage of the incident radiation, making it difficult or even impossible to determine the size and location of the reflective elements by passing them through of infrared radiation through the card. The shielding layer is generally impermeable to radiation, over a wide frequency range, which includes infrared radiation, visible light and X-rays. To the Impermeability In addition to soot or carbon, it can be increased for certain wavelengths add other materials. For example, the impermeability for X-rays increase by BaSO4 or lead salts.

The reflective elements 20 are preferably made by vapor deposition of aluminum or other metallic materials on the bottom of the magnetic Strip or tape generated before hot pressing. If the core material optically Smooth or polished, the material in question can also be applied to the core material to be vaporized; an alternative is vapor deposition on the top layer of the laminate possible. In the case of vapor deposition, aluminum is deposited in a vacuum. This condenses the aluminum vapor on the magnetic tape or other surface so that The aluminum permanently bonds to the base to be highly reflective To create surfaces that can easily be identified with the help of reflected infrared radiation permit. It was found that a vapor-deposited aluminum layer with a Strength in the range from 100 to 500 A a considerable part of the incident infrared radiation throwbackX If the thickness of the applied aluminum layer is increased, it increases the optical density of the layer and there will be a higher percentage of radiation reflects, Although there is no linear dependency here, one can Intentionally vary the thickness or density of the aluminum layer in order to produce optical signals to produce the intensity of which varies accordingly.

Of course, you could also use reflectors instead of the vapor-deposited aluminum use another type. Numerous other metallic elements and Alloys vapor deposition, and it is possible to use other methods in which suitable reflection properties result. It was also found that it it is possible to vaporize certain compounds, e.g. tin (II) oxide, and that here a detectable reflection occurs.

It has been shown that the surfaces of the usual magnetic Information carriers, e.g. most of the commercially available Magnetic tapes, are optically "rough" in the sense that they do not cause mirror reflection, but reflecting incident radiation diffusely. Are the reflective elements through direct evaporation generated on the surface of a magnetic medium, they also become visually rough. This leads to a diffuse reflection, so that It is difficult to identify the presence of the reflective elements for safety reasons the required accuracy. However, it is possible to have this optical roughness to be removed prior to vapor deposition using various methods. It was determined, that you can make the magnetic information carrier optically smooth in that a coating 30 is applied to the magnetic side of the tape, in the form of dries to a glossy layer. Numerous Kinds of coatings prove to be suitable as long as they are compatible with the reflectors, the magnetic medium and the core material of the card are compatible. It has shown that a copolymer of vinyl chloride and vinyl acetate, which in a corresponding Solvent, e.g. a mixture of 2-nitropropane and nitroethane, is dissolved for is useful for the stated purpose.

One such suitable copolymer is available from Union Carbide Corporation Marketed under the legally protected name "Vinylite VMCH". Once the coating has dried and, if necessary, hardened, it forms a surface of sufficient reflectivity or optical smoothness, so that also the vapor-deposited Elements are given appropriate reflectivity because they follow the shape of the Adjust cover. Other types of reflectors that are not made by vapor deposition there is no need to apply a coating.

In the most preferred embodiment, the material is reflective directly onto the above-described coating 30 of organic material vaporized. Because high temperatures cause wrinkling or otherwise Deformation of the magnetic tape during vapor deposition will be a Fat, E.g. the variety available under the trade name "Convalex-10" on the polyester side of the magnetic tape, which later came into contact during the vapor deposition process brought with a cooling plate or other device for dissipating heat will. The fat acts as a good conductor of heat, which is used to cool the magnetic tape After the end of the vapor deposition process, the fat is removed with the help of an appropriate Removed solvent. In the case of mass production, one could also use other facilities to use temperature control to avoid the use of fat and the subsequent To make cleaning unnecessary.

The magnetic strip 18 is preferably by means of the known Hot pressing process or other lamination process generated. Here is a Magnetic tape 19 on top of the top layer 24 by applying heat and pressure attached, and thereafter the polyester sheet shown in Fig. 2 is attached 21 deducted. About the magnetic medium and its reflective elements 20 to join the core material 22 and the top layer 24 is proposed the hot pressing process an adhesive layer 32 on the magnetic tape and / or the upper Layer 24, which is to be connected to the core material 22. It has shown, that for use as an adhesive in hot pressing the aforementioned product Vinylite VMCH is suitable if it is, for example, in a mixture of 2-nitropropane and nitroethane is resolved.

It has been found that a magnetic medium composed of gamma ferric oxide (t-Fe203), is essentially transparent to infrared radiation and a allows satisfactory recognition of the reflectors below. The -Fe203 is essentially opaque to normal visible radiation, so it does the makes underlying reflectors invisible to the naked eye. The coating The magnetic tape should not contain any soot, because this would be the incident infrared radiation absorb and thereby the reflected radiation dampen. If optimal results are to be achieved, the coating of the tape must not be Contains soot. However, a small percentage of carbon black can be allowed so long as a result, the reflected infrared radiation is not significantly changed or diffused is made.

Fig. 3 shows a simplified representation of a typical reader that can be used in conjunction with a credit card in accordance with the new version. To the one shown The assembly includes a magnetic read head 34 designed in a known manner, which is shown in FIG a predetermined distance from a generally designated 35 infrared detector is arranged; the detector 35 includes an infrared radiation source 36 and the actual detector 38. A shielding part 40 is preferably present, which covers part of the credit card and has a narrow slot 41, so that a narrow infrared beam can penetrate the magnetic medium and to the underlying reflective elements can get. While the credit card or the like. is transported by a corresponding device, not shown, the magnetic data using the magnetic head 34 and the reflective Elements 20 corresponding optical data with the aid of the detector or sensor 38 read. There are various infrared sensors and infrared radiation sources in retail that fulfill this task. Such a PbS-type detector is used by from Optoelectronics, Inc. under the model designation OE-20 brought.' This detector is for radiation in the wavelength range from 1 to 3 Micrometer is highly sensitive.

From Fig. 5 is the shape of that produced by the reflective elements visible data. While the credit card is under the optical detector 35 moved away, the intensity of the perceived infrared radiation varies between the background surfaces and the reflective surfaces to a considerable extent. In the absence of a reflective element, the sensor 38 generates the signal 56, the one negligible has low strength as a high percentage the incident infrared radiation from that in the underlying shielding layer 28 containing soot is absorbed. As soon as a reflective element 20 Moved under the detector, a signal 58 is generated as shown in FIG. 5, which has a significantly higher level than the signal 56. At the trailing edge of the reflective Elements, the signal goes back to the background level at which it was remains until the leading edge of the next reflective element from the probe 38 is detected.

Have all reflective elements been painted over and recorded, the generated optical signal pattern is evaluated to verify the authenticity of the card to consider. The number, size and location of the reflective elements can vary during the Manufacturing process can be varied. If necessary, the reflective elements can be placed under the influence of chance are generated, or lie within regulated limits, so that the resulting signal pattern of the card in question is not repeatable Way is assigned. You can train the security system so that the leading edges or the trailing edges of the reflectors or both types of edges can be detected.

It is also conceivable in the context of the innovation that it is the security system enables the surface area of the reflective elements to be examined or, if necessary, to disregard those signals emanating from certain elements; this would generally further increase the level of security.

Fig. 5a shows a modified structure for securing a Credit card or the like serving property according to the innovation.

As the optical detector produces a narrow beam of the reflected radiation samples the strength of the resulting signal to some extent the optical smoothness of those in contact with the reflective elements Affected interface. One can have an intermediate or secondary level of reflectivity obtain, if one intentionally changes the optical smoothness of this interface and e.g. worsened.

If the above-described organic coating is used, can it is disguised physically or chemically within surfaces, which completely or partially cover the reflective elements. Such areas are shown in Fig. 5a at 60 as hatched areas. The one within the surfaces The partial diffusion that takes place leads to a reduction in intensity the felt radiation. This results in a reduction in the signal level, as shown in Fig. 5a at 62. The two levels of reflectivity deliver a resulting signal pattern, which can be achieved with the help of a corresponding System can process in order to further increase the level of security. One would Disassemble credit card or grind the core material or magnetic medium, to determine the secondary reflection pattern, of course, the organic coating would changed or damaged in such a way that the intentionally changed surfaces do not change let distinguish more from the original shiny surfaces.

According to the invention it has been found that the organic coating can obscure by placing the desired surfaces in contact with one Piece of fabric or the like. brings that has an irregular surface and a corresponding Contains solvent. Part of the coating is then deformed by the solvent, and by regulating this process accordingly, it is possible to achieve the desired To achieve the degree of roughness. Is a coating made from the aforementioned material Vinylite VMCH is present, satisfactory results are obtained when using as Solvent e.g. methyl ethyl ketone is used. Of course you could get the one you want Can also produce an effect in other ways, e.g. by applying heat with help a corresponding tool made of iron or the like.

4 shows a typical security system in a block diagram for use in connection with a credit card or the like according to the innovation. One such The security system is described in patent application P 26, filed on May 26, 1976 23 708.1 of the applicant. There are several members of such a system data stations set up in different locations; one of those data stations that is designated as a whole by 42 in FIG. 4, has a card transport device 44, the above-described magnetic head 34 and the optical detector 35 is assigned. The signals from the magnetic read head 34 are fed to a circuit 46, while the optical data signals drive a circuit 48. the magnetic and optical data signals are passed through circuits 46 and 48 processed before they are fed to a transmission control device 50, which in turn feeds the signals to a central unit 52, which is an authentication module 54 is assigned.

The authentication module is programmed in such a way that it enables determine whether the presented credit card or the like. is real.

This test can be carried out in the most varied of ways, what depends on the structure of the system and the desired level of security directs. For example, one can choose a system in which the optical data read from the card at the time of its manufacture and in that by the central unit and the authentication module formed device according to the account number of the Card or other identification feature can be stored. Furthermore is it is possible to encrypt the optical data using an encryption algorithm to encrypt in order to increase the security level of the system. Will the card then evaluated with the help of the system, the optical data on the relevant terminal read, possibly encrypted and then with the in the central unit previously stored data or the code compared. Are the codes within pre-determined limits, which at the system in question are permitted, a confirmation signal is sent to the terminal to indicate that the card is real. On the other hand, does the generated code or information correspond does not meet the requirements of the system, a corresponding one meets at the terminal Signal on, whereupon the operator refuse to accept the card or May request additional information before continuing the operation he follows. Of course, the innovation is not limited to its use in conjunction with the security system according to FIG. 4, because it is possible for any person skilled in the art to develop security systems to create the most varied of types, by means of which the authenticity of a Credit card or the like can be determined.

As can be seen from the above description, it is very difficult to a credit card or the like in accordance with the innovation. to be imitated with features that serve as security or falsify.

The magnetic strip present on the top of the card fulfills A double task in that it contains not only magnetic data, but also obscures the underlying reflective elements so that they come with Do not allow visible radiation to be made visible with the help of. The reflective elements are preferably made of vapor-deposited metal. Such elements have a high Reflectivities on, however, are so thin that on top of the magnetic Strip no increases or the like. are present that can be recognized by a Could facilitate counterfeiters. Furthermore, it would be very difficult to get the vapor deposited Elements accessible by grinding away the core material or by disassembling the card to do, because this would destroy the extremely thin reflectors, or yours relative spatial arrangement through which the optical Signal pattern is determined would be changed. Because the reflective elements on are covered on both sides, it is impossible to depict them photographically working with reflected light or letting light pass through the card. Even a determination with the aid of X-rays does not lead to the desired results Results, which is partly due to the thinness of the elements as well as to the effect the shielding layer 28 is due.

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Claims (21)

Claims 0 data carrier, in particular credit card, from a Plastic core layer, optionally with a transparent cover layer is provided, which has a magnetic on one side Recording strips (magnetic strip, magnetic strip) for magnetic data recording and reproduction, characterized in that below the at least largely impermeable to normal visible light and to electromagnetic light Radiation of predetermined characteristics permeable formed magnetic recording strip (18) a series of separate thin reflectors (20) for the electromagnetic Radiation, in particular infrared radiation, is provided that the recording strip (18) on its underside facing the reflectors (20) with an optically smooth, covering layer (30) permeable to electromagnetic radiation with the same microtopographical characteristics such as the reflectors is provided and that the Thin reflectors applied to the underside of the coating layer in the form of particles Include elements each having a reflective surface adjacent to the coating layer and practically the same micro-topographical characteristic as the one that contains it Have underside of the coating layer. 2. Data carrier according to claim 1, characterized in that g e k e n n -z e i c h n e t that the smoothness of the reflector particles is about the smoothness of the coating layer (30) equals 3. Data carrier according to claim 1, 2 or 3, characterized in that g e k e n n -z e i c h n e t that the reflectors (20) made of metal layer sections, in particular aluminum layer sections, exist, which are applied in particulate form or by means of the coating layer (30) connected to the magnetic strip (1-8). 4. Data carrier according to one of claims 1 to 3, characterized g e k e n It is noted that the magnetic Strips (18) with the reflectors (20) by means of an adhesive layer (32) connected to the top of the card. 5. Data carrier with a cover layer according to one of claims 1 to 4, characterized in that the magnetic strip (18) with the Reflectors (20) with one between the core layer (22) and the cover layer (24) attached shielding layer (28) is underlaid. 6. Data carrier according to one of claims 1 to 5, characterized g e k e n It is noted that the distance between the reflectors (20) is irregular. 7. A data carrier according to claim 6, characterized in that it is e k e n n z ei c h -n e t that the distance between the reflectors (20) is randomly irregular. 8. Data carrier according to one of claims 1 to 7, characterized in that g e k e n n z e i c h n e t that sections (60) of the coating layer (20) have adjacent reflectors (20) are partially covered and designed with less optical smoothness, like the rest of the surface of the coating layer (30). 9. Data carriers for data carrier cards, in particular credit cards or Like., especially according to one of claims 1 to 8, with a magnetic tape whose thin, flexible carrier tape on one side with a magnetic recording strip is provided, thereby indicated, - that the magnetic recording strip (18) at least along part of its length with a coating layer (30) known surface characteristics is covered and that a variety of electromagnetic Radiation reflecting reflectors (20), which over the length of the magnetic tape in Distances are distributed, are applied to the coating layer in particulate form and have a surface characteristic comparable to the coating layer. 10. Data carrier according to claim 9, characterized in that g e k e n n -z e-i c h n e t that the coating layer (30) has a generally optically smooth surface, to which the reflectors (20) are applied in particulate form, and that the reflective Surfaces of the reflectors have a comparable smoothness. 11. A data carrier according to claim 9, characterized in that it k e n n -z e i c h n e t that the coating layer (30) is applied to the magnetic recording strip (18) applied coating. 12. A data carrier according to claim 11, characterized in that g e k e n n -z e i c h n e t that the coating layer (30) is an adhesive layer which the magnetic on drawing strips (18) connects to the reflectors (20). 13. Process for producing a document secured against forgery, e.g. a credit card or the like according to claim 1, characterized in that e t that a document core layer and one opaque to normal visible light magnetic recording tape are provided that the core layer or the Magnetic tape with a reflector receiving surface with generally known microtopographic Characteristic is provided that particles of a reflector material on the reflector receiving surface to build up a thin area thereof in different places to form several Radiant energy reflecting elements, each with a reflector surface with the same microtographic images. . ~ is applied, characteristics such as the reflector receiving surface and that the core layer and the recording tape so are interconnected that the radiant energy reflecting elements lie between these two parts. 14. The method according to claim 13, characterized in that g e k e n n z e i c h -n e t that the reflector elements are covered with a coating layer, the outer surface has a common microtopographical characteristic. 15. The method according to claim 14, characterized in that g e k e n n z e i c h -n e t that an adhesive layer is applied as a coating layer and with it the Reflector elements with the data carrier strip and / or the core layer get connected. 16. The method according to claim 15, characterized in that it is e k e n n -z e i c h n e t that joining takes place in the presence of heat and / or pressure. 17. Method of producing a security data carrier. qekennz. tape according to one of claims 9 to 12, that a magnetic tape with a magnetic Recording strips on one side with the usual microtopographical properties is provided and on these AufnEel particles of a reflector material to build up a thin area thereof at various locations on this receiving area to form several elements suitable for reflecting radiant energy applied, in particular vapor-deposited, are a reflector surface with microtopographic Have characteristics substantially the same as those of the receiving surface of the recording strip for the reflectors. 18. The method according to claim 17, characterized in that g e k e n n -z e i c h n e t that the magnetic recording strip on before the precipitation of the reflector material provided with a generally optically smooth surface by means of a smoothing process will. 19. The method as claimed in claim 17, characterized in that it is e k e n n -z e i e h n e t that at least a part of the free surface of the magnetic recording tape is provided with a coating layer, the free surface of the surface for Incorporating reflectors with known microtopographical characteristics, after which the reflector material is applied to this free surface. 20. The method according to claim 19, characterized in that g e k e n n -z e i c h n e t that the reflector receiving surface is generally made optically smooth so that the reflection of the reflective elements generally corresponds to the mirror reflection. 21. The method as claimed in claim 19, characterized in that it is e k e n n -z e i c h n e t that an adhesive layer is applied as the Obazugsschicht with which the reflectors can be connected to the magnetic recording strip.