MXPA00002510A - Radio frequency identification tag on flexible substrate - Google Patents

Abstract

An enhanced identification tag (20) produces an identification (ID) signal (38) carrying identification information, capable of being interpreted by an electronic reader device (30). An identification tag (20) in accordance with the invention is characterized by a flexible substrate (22), programmable encoder circuitry (28) formed on said substrate (22) defining identification information, an antenna (24) and signal generator circuitry (26) carried by said substrate (22) responsive to said encoder circuitry (28) for applying a radio frequency signal bearing said identification information (36) to said antenna (24). A preferred tag is fabricated using a printing process to mark a conductive pattern, e.g., comprised of a conductive ink based on silver, carbon, etc., on a flexible substrate (22), plastic type material. In a typical application, the flexible substrate (22) is then preferably used to form a wrist band that can be used to identify an individual to permit, deny or otherwise determine the level of access to an area, e.g., a concert, a work area or other restricted environment.

Description

RADIO FREQUENCY IDENTIFICATION LABEL ON A FLEXIBLE SUBSTRATE RELATED REQUEST This application claims the benefit of the provisional application of E.U.A. No. 60 / 058,518, filed September 11, 1997. This invention relates to identification systems and labels or tags thereof to produce a radio frequency identification signal that can be interpreted by an electronic reading device.

BACKGROUND OF THE INVENTION The commonly known identification systems use a reading device or reader that emits an interrogation signal in such a way that an identification tag which is in the vicinity returns an identification signal to that reader. Among the known types of identification tags are non-electronic passive tags, for example, those with a bar code, which are optically identified by the reader in accordance with a printed template. These labels and the systems for manufacturing them by an essentially continuous manufacturing process have been described in US Pat. No. 5,615,504 issued to Peterson et al., And the US patent. No. 5,609,716 issued to Mosher, Jr., both assigned to the beneficiary of this invention. These systems require that the bar code is visible, that is, that it is within the visual horizon of the reader. IDRF (radio frequency identification) tags, which respond to a radio frequency transmission from a reader for the tag to return an electronic signal to that reader, are also well known. The patent of E.U.A. No. 5,493,805 issued to Penuela illustrates, for example, a flexible bracelet or wristband with an integrated memory or tag circuit which can be accessed by a radio frequency signal, and the U.S. patent. No. 4,333,072 to Beigel, which illustrates circuit examples for an IDRF tag.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to an improved identification tag for producing an identification (ID) signal, that is, a radiofrequency (RF) signal carrying identification information, which can be interpreted by an electronic reading device distanced from the label, but in the vicinity of it, for example at a distance between 0 and 4 m. An identification tag according to the invention is characterized by a programmable signal coding circuit formed on a flexible substrate, which contains identification information, an antenna, and a signal generating circuit on the aforesaid substrate and which responds to the coding circuit of signals mentioned above for applying a radiofrequency signal carrying the aforementioned identification information to the antenna described above. In accordance with one aspect of the invention, the programmable signal coding circuit is formed by conductive tracks or circuits selectively formed on the substrate, for example, by conductive ink printing, metal deposition or other convenient technique for in-line fabrication. keep going. According to a different aspect of the invention, the signal generating circuit includes one or more reactance elements (inductance and / or capacitance) formed on the aforementioned substrate by a printing or analogous technique suitable for continuous line manufacturing. An identification tag according to the invention can be activated to transmit its identification signal in various forms and consequently be useful in multiple types of identification systems. For example, the system may use an interrogator-reader device that generates an interrogation signal so that in response the label returns an identification signal. Alternatively, the tag may be configured to transmit its identification signal in response to some other event, such as the end of a predetermined time interval.

The novel features of the invention are described in detail in the claims appended hereto. The following description will be understood more clearly if it is compared with the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figures 1 and 2 illustrate an example of an identification device of a prior art that includes a bracelet with identification information printed on a bar code thereon; Figure 3 is a schematic diagram of a continuous line manufacturing process of a prior art, for manufacturing the identification device of Figures 1 and 2; Figure 4 illustrates a simplified delineated diagram of an identification tag in accordance with this invention for producing a radio frequency signal that transmits identification information; Figure 5 is a schematic diagram of a circuit of a label in accordance with the invention that includes selectively activated inductor-capacitor (LC) components, suitable for manufacturing by printing techniques; Figures 6A and 6B are, respectively, a top and bottom view of the printed portions of the passive label of Figure 5; Figure 7 is a schematic circuit diagram of a label circuit, for example, a sequence or sequential counter mechanism, including switches and / or semiconductor amplifiers that are selectively activated to emit a radio frequency signal that transmits information of identification; Figures 8A to 8C, respectively, illustrate the upper and lower sides of an intermediate layer of flexible substrate, as well as the upper side of a topsheet, which as a whole define the circuits of Figure 7; Figure 9 is an enlargement illustrating three laminated layers of flexible substrate material forming the label of Figure 7; and Figure 10 illustrates a schematic diagram of an apparatus (a modification of the illustration in Figure 3) for the continuous line manufacture of the preferred labels of Figures 5 to 9.

DESCRIPTION OF THE PREFERRED MODALITIES This invention relates to an improved identification tag for producing an identification (ID) signal, that is, a radio frequency (RF) signal that carries or transmits identification information, which can be interpreted by an electronic reading device. According to the invention, an identification tag is characterized by a flexible substrate, a programmable signal coding circuit formed on that substrate and defining the identification information, an antenna and a signal generating circuit that responds to the signal coding circuit aforementioned to apply a radio frequency signal that transmits that identification information to the antenna described above. Preferably, in accordance with the invention, continuous line manufacturing techniques are used in the manufacture of the label, for example, printing, to form a conductive pattern or template, which includes for example, a conductive ink with a silver base, carbon, etc., on a flexible substrate, for example, polyethylene, polyvinyl chloride or other plastic type material. It should be noted that the term "printing", as used herein, has a broad connotation that includes any manufacturing technique to form, deposit or otherwise trace a track or circuit of conductive material. Figures 1 and 2 correspond to figures 1 and 2 of the U.S. patent. No. 5,609,716, and illustrate an example of an identification device 10 of a prior art, including a flexible bracelet 12 carrying identification information, commonly printed information on a bar code that can be read visually. Figures 1 and 2 can be manufactured in a continuous line manufacturing process as described in Figure 3. The use of bar code technology or any other technology that can be read visually is limited to applications in the that it is practical to conserve the visual horizon between the identification device and the reader. In applications where it is not possible to preserve this visual horizon, it is convenient to use radiofrequency technology as described, for example, in the patent of the U.S.A. No. 4, 333, 072. The present invention relates to radio frequency identification (IDRF) tags that can be used on bracelets and the like manufactured by a continuous line method as broadly described in FIG. 3. In a FIG. common application, the IDRF tag can be used to identify a person, to allow, deny or determine the level of access to an area, for example, a concert, a work area or any other restricted environment or to transmit descriptive information regarding to a person, for example, for the administration of patients in a hospital. Figure 4 illustrates an example of tag 20 according to the invention consisting mainly of (1) a flexible substrate 22, (2) an antenna 24, (3) a signal generating circuit 26 on the flexible substrate 22 and (4) ) a programmable signal coding circuit 28 also formed on the flexible substrate 22. In a common mode, a reader 30 emits a radio frequency (RF) identification signal (typically between 100 KHz and 3 GHz) by way of the track 36. and which is received by the antenna 24. The received interrogation signal is connected by way of the track 34 to the signal generating circuit 26 which generates a radio frequency identification signal carrying identification information defined by the signal coding circuit 28. The identification signal is sent to antenna 24 via track 36, which transmits it back to reader 30 via track 38. According to the invention, it is possible to The signal encoder circuit 28 is adjusted to meet specific application requirements. For example, the circuit 28 may function as a read only memory, programmed in manufacturing, or as a read-write memory that is permanent but reprogrammable. The ability to read-write is useful for capturing information on the label after its manufacture, for example, at the time when the label is assigned to a particular person. Various known techniques can be used to write, that is, to alter, the memory in order to define the identification information. The specific embodiments of the signal encoding circuit 28 may also include both read memory portions only and portions of read-write memory. In a common reading mode only the signal coding circuit 28 can include a plurality of electrical connections 40 selectively formed towards the signal generating circuit 26, by forming electrical connections towards the input or power supply of the signal generating circuit, for example, by means of printing with conductive ink on the flexible substrate 22. Accordingly, the operation, for example, the tuning of the signal generating circuit 26, is modified by the identification information defined by the signal encoding circuit 28 to generate the signal of identification. In another embodiment, the signal coding circuit 28 may include a semiconductor memory, for example, a read-only device or a read-write device (either transient or permanent) so that the information stored within the memory defines the identification information. This semiconductor memory can be configured to allow its remote programming, for example, by means of a radio frequency control signal. It is possible to implement the signal generator circuit 26 either in the form of an active circuit (which consumes energy, for example, switches and / or semiconductor amplifiers) or passive (ie, reflective). In the case of an active implementation, a power supply 42, for example a battery, is used as the power source for the signal generator 26. Alternatively, the power supply 42 can extract the energy of the received RF signal (see U.S. Patent No. 4,333,072 to Beigel). In another embodiment of the signal generator, the signal generator 26 can output a signal in response to a specific trigger event, for example, energy received from a timer 44 or sensory input on the label. In this embodiment, the signal generator 26 generates a radio frequency signal that transmits the identification information to the reader 30 via the track 38 without requiring the interrogation signal carrying the track 32.

The substrate 22 carries the signal generating circuit 26, that is, the latter is mounted in the vicinity of, or formed on, the substrate. In a preferred embodiment illustrated in Figure 5, the signal generating circuit 26 is implemented by printing techniques using conductive ink on the flexible substrate 22. In this embodiment, a transmission line with delay 50, connected to the antenna 24 ( essentially an inductor), is selectively formed from a variety of inductors (L) 52 and capacitors (C) 54. The conductive ink 55 is printed on the flexible substrate 22 to selectively activate certain portions of the circuit, that is, the capacitors 54 which they form each portion LC of the transmission line with delay 50, which defines the identification signal. While this embodiment illustrates a signal generator circuit 26 implemented from reactance elements, that is, inductors and capacitors, which reflect a modified interrogation signal as the identification signal, it will be further described below how to implement a generator circuit of active signals using similar printing techniques, but which emits an identification signal or reflects a modified interrogation signal based on variations in the energy absorption of the interrogation signal by the label (see US Pat. No. 4,333, 072). If, for example, a semi-duplex transmission procedure is used, only a portion of the tag / reader pair transmits a signal at a certain time. In this way, the reader transmits an interrogation signal that is rectified and stored in a capacitor inside the label. The reader then interrupts its signal and prepares to receive the signals of entry or arrival (low level) and the label transmits its identification signal using the energy stored in the capacitor. This procedure is repeated until the reader confirms the successful reception of that identification signal. Alternatively, using as an example a full duplex transmission method, the reader and the tag are active simultaneously. The reader continuously transmits an activating signal to the label, which is rectified and stored in a capacitor usually smaller than that used in the example of the half-duplex label. The tag transmits an identification signal when variable winding its antenna coil in a configuration corresponding to the identification code. The reader receives and interprets the identification signal during the transmission of the interrogation signal. During operation, the antenna 24 receives the electromagnetic signal by means of the track 32 and communicates this received signal, by way of the track 34, to the transmission line with delay 50. In response to the signal received in the track 34, the delay transmission line 50 reflects back a single identification signal (depending on the activated LC branch circuits) to the antenna 24, and this signal can be detected by the remote reader 30.

Figures 6A and 6B, respectively, illustrate examples of configurations or templates that can be drawn on the upper 56 and lower 58 sides of the flexible substrate 22 to conform the circuit of Figure 5. The IDRF circuit, that is, the coding circuit of signals 28 and the signal generating circuit 26, is implemented when printing templates on the flexible substrate 22 using a conductive ink 55. For example, the inductors 52 are preferably formed by a curved track or circuit printed on one side of the substrate 22, while capacitors 54, are implemented by printing a first conductive sheet 60 on the upper side 56 of the substrate and a second conductive sheet 62 on the lower side 58 of the substrate, thereby forming two conductive sheets 60 and 62 separated by a dielectric substrate. 22. By selectively printing / depositing the second conductive sheet 62 on the underside 58 of the substrate, it is possible to selectively form the capacitors 54 to change the reflection characteristics of the transmission line with delay 50, that is, to form the signal coding circuit 28. In Figure 6B, for example, while the second conductive sheet 62a is present and therefore the capacitor 54a exists, there is no conductive sheet 62b and therefore there is no capacitor 54b either. In figure 5, the antenna 24 is illustrated as a simple inductor. However, in the example of Figure 6, the antenna 24 has a pair of inductors 64 and 66 connected by a capacitor 68 located between them. Alternatively, it is possible to drill or perforate an internal connection (not shown) through the substrate 22, which can be filled with conductive ink 55 to form a simple inductor antenna 24 as illustrated in FIG. 5. Optionally, it is possible to print visually identifiable information on the substrate 22, for example, a photograph 70 and / or a bar code configuration 72. Alternatively, it is possible to use a bar code configuration that provides electrical connections to determine the identification signal, that is, performing the function of the conductive ink 55, as well as providing a means to visually identify the label. To protect and isolate the conductive templates from an electrical interaction with a marked object, for example a person's wrist, layers of flexible material are added to the upper 56 and lower 58 sides of the substrate (see Figure 10). In another preferred embodiment, it is possible to print or otherwise deposit a configuration of conductive polymers, for example based on graphite, semiconductors and insulators, on the flexible substrate 22, to form the signal generator 26 and / or the coding circuit of signals 28 from a variety of switches and / or semiconductor amplifiers, for example, field effect transistors (TEC). An example of a technique for making this device, referred to as an organic semiconductor, is described in an article published by Garnier et al., And entitled "All-Polymer Field-Effect Transistor Realized by Printing Techniques" (Science, Vol. 275, September 16, 1994) which is incorporated herein by reference. The creation of an IDRF tag from active circuits, for example, TEC or other transistors, presents important advantages. For example, while the reflective circuit illustrated in Figure 5 is an efficient circuit for a single detection by a reader 30, there are certain limitations. Commonly, reflective circuits have a limited range and the characteristics of the reflected signal are restricted to the frequency range and time period of the electromagnetic interrogation signal on track 32. However, active circuits can respond to the signal of interrogation by emitting an identification signal with different frequency characteristics and / or the signal may be delayed for a predetermined time span of the received interrogation signal. In addition, the active circuits can present an identification signal with a higher energy and with a higher data content that facilitate identification by the reader 30. There are other technologies to create other additional components as part of the circuits of the IDRF tag. by applying printing techniques on the flexible substrate. For example, a battery is described in an article by Davis entitled "Johns Hopkins Scientists Créate All-Polymer Battery" (PCIM, February 1997); the LEDs, that is, the diodes, made of organic semiconductors, are also known in the art, and the resistors can be implemented by using different compositions for the conductive ink lines printed on the substrate, restricting the width of the printed line or extending its length.

Figure 7 illustrates an example of implementation of the IDRF tag, using active circuits (similar to those illustrated in U.S. Patent No. 4,333,072) which can be implemented by manufacturing techniques by printing on a flexible substrate. In essence, the antenna 24 receives an electromagnetic interrogation signal that is half-wave rectified by the combination of the diode 74 and the capacitor 76 to supply power (V +) to the active signal generator circuit 78, implemented as organic semiconductors (e.g. a plurality of semiconductor switches or amplifiers 80 used to form the circuit 78, for example, a counter mechanism in sequence as described in U.S. Patent No. 4,333,072). Alternatively, it is possible to activate the signal generating circuit 78 with a battery. The interrogation signal 32 is connected to the signal generating circuit 78 by means of the track 84, where it is used as the clock input. Depending on which inputs 86 are connected to ground 88 using fixed attenuators of conductive ink 55 (thus comprising the signal coding circuit), the signal generating circuit 78 emits an identification signal by means of track 89 which activates the charging circuit 90 (which preferably includes a TEC and an optional load resistor) in a predetermined sequence. This loading of the received signal can be detected remotely by the reader 30. Figures 8 and 9 illustrate an example of implementing the circuits of Figure 7 as a three layer sheet of flexible substrate 92, 94 and 96, with conducting polymers, semiconductors and insulators printed on it to form organic semiconductors, capacitors and inductors. The flexible substrate intermediate layer 94 has polymer configurations printed on its upper 98 and lower 100 surfaces. Inductors and capacitors are formed as described above with reference to Figure 6, while the charging circuit 90 and the generating circuit of signals 78 are formed as organic semiconductors, in accordance with the description of Garnier et al. The fixed attenuators between the inputs 86 of the signal generating circuit 78 and the ground 88 remain open on the upper surface of the intermediate layer 94 of the substrate. To protect the deposited circuit, an upper layer of the substrate 92 is laminated on the intermediate layer 94 and a lower layer of the substrate 96 is laminated below (see also figure 10). However, the upper layer 92 of the substrate further has a window 102 corresponding to the position of the fixed attenuators of the inlets 86 and of the ground 88. Accordingly, it is possible to print or otherwise deposit the conductive ink 55 through of the window 102 for programming the coding of the signal generating circuit 78, that is, defining the signal encoding circuit 28. Commonly, the inputs 86 are high impedance inputs, for example, when the signal generating circuit 78 is based on TEC. In this way, the options with respect to the conductive ink 55 are greatly increased, that is, a wide range of inks of different resistivity can be used.

This type of label structure is suitable for continuous line manufacturing. Alternatively, it is possible to make these labels in separate steps. For example, the three-layered sheet formed of the layers 92, 94 and 96 can first be formed by including the depositions related to the intermediate layer 94 of the substrate and, subsequently, at another time and / or location, for example, at the place where the labels are distributed, these can be programmed by coding them through the window 102. Figure 10 illustrates a schematic diagram of an example of apparatus 104 (a modification of the one illustrated in figure 3) to manufacture the preferred labels 20 of figures 4 to 8. In operation, the flexible substrate 22 is distributed from the roller 106 and fed through a variety of processing stations 108a-n which print the templates or conductive, semiconducting and insulating configurations required to add connections and / or define the circuits comprising the circuit set of the IDRF tag described above. The processing stations 108 perform various functions, depending on the processing, for example, printing various layers of conductive, semiconducting and insulating ink, drying the ink, etc. Once the printing is finished, layers of flexible material 110 and 112 are preferably added via a rolling station 114 to the substrate 22. Next, fixing means 116 is placed or formed on the substrate 22 and the substrate 22 is cut using a cutter 118 to form, identification tag 20 completed. This apparatus 104 may operate either on demand, that is, each time a new label is required, or at an essentially continuous rate for the continuous line manufacture of a variety of uniquely identifiable labels. Alternatively, it is possible to make the label in the factory but without programming it completely. The partially programmed labels can be sent in continuous rolls to the places where they will be displayed and where an independent programming device (not illustrated) can complete the programming of the labels on request, for example, depositing a template of conductive ink in accordance with the described above and / or any other type of identification information that can be detected visually. Although this invention has been described in detail only with reference to preferred embodiments herein, those skilled in the art will appreciate that various modifications are possible without thereby departing from the invention.

Claims (20)

NOVELTY OF THE INVENTION CLAIMS

1. - An identification tag for producing a radiofrequency identification signal, and this tag includes: a flexible substrate; a programmable signal coding circuit formed on the aforesaid substrate to define the identification information; an antenna; and a signal generating circuit on the aforementioned substrate and responding to the aforementioned signal coding circuit to apply a radio frequency signal that transmits the identification information to the antenna described above.

2. The identification tag according to claim 1, further characterized in that the aforementioned signal generating circuit includes at least one semiconductor device formed by depositions on the substrate described above.

3. The identification tag according to claim 2, further characterized in that the aforementioned semiconductor device within the signal generating circuit is made of polymers deposited on the substrate described above.

4. The identification tag according to claim 1, further characterized in that the aforementioned signal generating circuit includes reactance elements formed by deposition on the substrate described above.

5. The identification tag according to claim 1, further characterized in that the signal coding circuit includes a plurality of conductive tracks selectively formed on the substrate described above to define the aforementioned identification information.

6. The identification tag according to claim 5, further characterized in that the signal coding circuit includes a plurality of conductive tracks selectively deposited on the substrate described above to define the aforementioned identification information.

7. The identification tag according to claim 1, further characterized in that the signal coding circuit includes at least one semiconductor device formed by deposition on the substrate described above.

8. The identification tag according to claim 7, further characterized in that the aforementioned semiconductor device within the signal coding circuit described above is made of polymers deposited on the aforesaid substrate.

9. The identification tag according to claim 1, further characterized in that the aforementioned antenna is created by depositing a conductive track on the substrate described above.

10. - A system for providing identification information, and this system includes: a reader for emitting an electromagnetic signal; a label that responds to that electromagnetic signal to produce an identification signal in response thereto, and that label includes: a flexible substrate; an antenna for receiving the electromagnetic signal described above, mounted on the aforementioned flexible substrate; circuits connected to that antenna to generate the signal described above in response to the aforementioned electromagnetic signal received by the antenna; and a first conductive ink template printed on the aforementioned flexible substrate, defining at least one of a variety of eligible electrical connections connected to the above-described circuits to define the aforementioned identification signal; and characterized because the reader described above responds to that identification signal.

11. The identification tag according to claim 10, further characterized in that the aforementioned circuits are defined by a second conductive ink template and characterized in that the second conductive ink template defines a variety of selectively activated reactance elements that define at the same time the signal identification signal described above.

12. The identification tag according to claim 10, further characterized in that the circuits include a semiconductor integrated circuit and characterized in that the first conductive ink template selectively activates one or more of a variety of inputs to those circuits to define the identification signal.

13. The identification tag according to claim 10, further characterized in that the circuits include a second template of conductive ink and characterized in that the second template conductive ink defines a variety of semiconductor devices on the flexible substrate described above, characterized in that the first conductive ink template described above activates one or more of a variety of inputs to those circuits to define the aforesaid identification signal.

14. A method for making an identification tag to produce a radio frequency identification signal, and this method includes the steps of: distributing a continuous strip of flexible substrate from a distribution assembly; depositing a first conductive ink template on the aforementioned flexible substrate to form an antenna; depositing a second template of conductive ink on the flexible substrate to form a signal generating circuit for applying the aforementioned radio frequency identification signal which transmits the identification information to the antenna described above; and, separating a portion of the flexible substrate, including the first and second deposited templates described above to define the aforementioned identification tag.

15. - The method according to claim 14, further characterized in that the second conductive ink template defines a variety of semiconductor devices.

16. The method according to claim 14, further characterized in that the second conductive ink template defines reactance elements.

17. The method according to claim 14, further characterized in that it includes the step of selectively depositing a third template of conductive ink on the flexible substrate described above to define by programming the aforementioned identification information.

18. The method according to claim 14, further characterized in that it includes the step of placing fixing means on the above-described separate portion of the aforementioned flexible substrate.

19. The method according to claim 14, further characterized in that it includes the step of depositing a third template of conductive ink on the flexible substrate described above to determine the radio frequency identification signal produced by the signal generating circuit.

20. The method according to claim 19, further characterized in that the above described step of depositing a third conductive ink template further defines a visually identifiable configuration.