Abstract:
A wireless identification device comprising a housing; circuitry in the housing configured to provide a signal to identify the device in response to an interrogation signal; and a selectively actuated switch supported by the housing and permitting operation of the circuitry only while the switch is actuated. A method of manufacturing a wireless identification device, the method comprising configuring circuitry to provide a signal to identify the device in response to an interrogation signal; coupling the circuitry to a selectively actuated switch, such that the circuitry provides the signal only while the switch is actuated; and encasing the circuitry in a housing such that the switch is actuable from outside the housing by touching a portion of the housing.

Description:
TECHNICAL FIELD  
         [0001]    This invention relates to radio frequency communication devices. More particularly, the invention relates to radio frequency identification devices for inventory control, object monitoring, determining the existence, location or movement of objects, or for remote automated payment.  
         BACKGROUND OF THE INVENTION  
         [0002]    As large numbers of objects are moved in inventory, product manufacturing, and merchandising operations, there is a continuous challenge to accurately monitor the location and flow of objects. Additionally, there is a continuing goal to interrogate the location of objects in an inexpensive and streamlined manner. One way of tracking objects is with an electronic identification system.  
           [0003]    One presently available electronic identification system utilizes a magnetic coupling system. In some cases, the tag device may be provided with a unique identification code in order to distinguish between a number of different tags. Typically, the tag devices are entirely passive (have no power supply), which results in a small and portable package. However, this identification system is only capable of operation over a relatively short range, limited by the size of a magnetic field used to supply power to the tags and to communicate with the tags.  
           [0004]    Another electronic identification system utilizes a large active transponder device affixed to an object to be monitored which receives a signal from an interrogator. The device receives the signal, then generates and transmits a responsive signal. The interrogation signal and the responsive signal are typically radio-frequency (RF) signals produced by an RF transmitter circuit. Because active devices have their own power sources, and do not need to be in close proximity to an interrogator or reader to receive power via magnetic coupling. Therefore, active transponder devices tend to be more suitable for applications requiring tracking of a tagged device that may not be in close proximity to an interrogator. For example, active transponder devices tend to be more suitable for inventory control or tracking.  
           [0005]    Electronic identification systems can also be used for remote payment. For example, when a radio frequency identification device passes an interrogator at a toll booth, the toll booth can determine the identity of the radio frequency identification device, and thus of the owner of the device, and debit an account held by the owner for payment of toll or can receive a credit card number against which the toll can be charged. Similarly, remote payment is possible for a variety of other goods or services. An electronic identification system which can be used as a radio frequency identification device, and various applications for such devices are described in detail in commonly assigned U.S. patent application Ser. No. 08/705,043, filed Aug. 29, 1996, and incorporated herein by reference.  
           [0006]    For active devices, battery drain is an important issue. The battery may be drained by spurious emissions of the necessary radiation to activate a radio frequency identification device. A power conservation problem is posed by such implementations where batteries are used to supply power to the circuitry of the radio frequency identification device. If the circuitry operates continuously at full power, battery life will be short, and device will have to be frequently replaced. If the battery is permanently sealed in a housing, replacement of the battery will be difficult or impossible. One reason for sealing the battery with the circuitry in a housing is to simplify the design and construction, to reduce the cost of production, and protect the electrical interconnections between devices. Another reason is protection of the battery and circuitry from moisture and contaminants. A third reason is to enhance the cosmetic appeal of the device by eliminating the need for an access port or door otherwise necessary to insert and remove the battery. When the battery is discharged, the entire device is then discarded. It is therefore desirable in such embodiments applications to employ power conservation techniques in order to extend useful life.  
           [0007]    Additionally, for security control, a holder of an active or passive radio frequency identification device may want to prevent unwanted reading of the radio frequency identification device. One potential problem with existing radio frequency identification devices, particularly those with large communication ranges, is that the holder of the device may not have control over when the device is being interrogated. There are times when the holder would want the device to be interrogated, such as to authorize payment. On the other hand, there are other times when the holder would not want the device to be interrogated. For example, if the device is interrogated to seek payment for a particular service, another service provider who is related to or has a marketing deal with the first service provider may seek to solicit business from the holder when the holder enters the premises of the second service provider. There may be sensitive information on the device, such as health information, address information, purchase histories, credit information, that the holder would not want to have accessed without knowledge or approval.  
           [0008]    Therefore, there is a need to provide a holder of a radio frequency identification device with the ability to control whether the device is interrogated.  
         SUMMARY OF THE INVENTION  
         [0009]    The invention provides a wireless identification device including a housing, and circuitry in the housing configured to provide a signal to identify the device in response to an interrogation signal. A selectively actuated switch is supported by the housing and permits operation of the circuitry only while the switch is actuated.  
           [0010]    In one aspect of the invention, the switch is a momentary switch.  
           [0011]    One aspect of the invention provides a RFID device including a push button switch which allows the RFID device to become temporarily active. The user of the device has control over when the RFID device responds to an interrogator.  
           [0012]    In one aspect of the invention, the switch is coupled to the power supply of an active RFID device, or a power supply receiver in a passive or magnetically coupled device. While the switch is pushed, the RFID device can be interrogated by a reader. In one embodiment, where the switch is coupled to the power supply, the device includes a non-volatile memory.  
           [0013]    In one aspect of the invention, the switch sets a digital circuit flag in an active device to allow the device to operate momentarily. In another aspect of the invention, the switch sets a digital circuit flag in a passive device, when RF power is available, to allow the device to operate momentarily.  
           [0014]    One embodiment of the invention provides a radio frequency identification device comprising an integrated circuit including a receiver, a transmitter, and a microprocessor. In one embodiment, the integrated circuit is a monolithic single die single metal layer integrated circuit including the receiver, the transmitter, and the microprocessor. The device of this embodiment includes an active transponder, instead of a transponder which relies on magnetic coupling for power, and therefore has a much greater range.  
           [0015]    Another aspect of the invention provides a method of manufacturing a wireless identification device. Circuitry is configured to provide a signal to identify the device in response to an interrogation signal. The circuitry is coupled to a selectively actuated switch, such that the circuitry provides the signal only while the switch is actuated. The circuitry is encased in a housing such that the switch is actuable from outside the housing by touching a portion of the housing. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    Preferred embodiments of the invention are described below with reference to the following accompanying drawings.  
         [0017]    [0017]FIG. 1 is a high level circuit schematic showing an interrogator and a radio frequency identification device embodying the invention.  
         [0018]    [0018]FIG. 2 is a front view of a housing, in the form of a badge or card, supporting the circuit of FIG. 1 according to one embodiment the invention.  
         [0019]    [0019]FIG. 3 is a front view of a housing supporting the circuit of FIG. 1 according to another embodiment of the invention.  
         [0020]    [0020]FIG. 4 is a circuit schematic of an active radio frequency identification device in accordance with one embodiment of the invention.  
         [0021]    [0021]FIG. 5 is a circuit schematic of a passive radio frequency identification device in accordance with one embodiment of the invention.  
         [0022]    [0022]FIG. 6 is a front elevational view, partly broken away, showing construction details of a switch included in the radio frequency identification device of FIG. 1.  
         [0023]    [0023]FIG. 7 is a plan view showing construction details of the switch of FIG. 6.  
         [0024]    [0024]FIG. 8 is a plan view showing construction details of the radio frequency identification device of FIG. 1 with the switch of FIG. 6 being located in accordance with one embodiment of the invention.  
         [0025]    [0025]FIG. 9 is a plan view showing construction details of the radio frequency identification device of FIG. 1 with the switch of FIG. 6 being located in accordance with another embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]    This disclosure of the invention is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8).  
         [0027]    [0027]FIG. 1 illustrates a radio frequency data communication device  12  in accordance with one embodiment of the invention. In the illustrated embodiment, the radio frequency data communication device  12  includes RFID circuitry  16 . In the illustrated embodiment, the RFID circuitry is defined by an integrated circuit as described in the above-incorporated patent application Ser. No. 08/705,043, filed Aug. 29, 1996. Other embodiments are possible. A power source  18  is connected to the integrated circuit  16  to supply power to the integrated circuit  16 . In one embodiment, the power source  18  comprises a battery. In an alternative embodiment, the power source comprises a magnetic coil that receives power via magnetic coupling from an external reader as is known in the art; e.g., as disclosed in U.S. Pat. No. 5,113,184 to Katayama. The device  12  further includes at least one antenna  14  connected to the circuitry  16  for radio frequency transmission and reception by the circuitry  16 .  
         [0028]    The device  12  transmits and receives radio frequency communications to and from an interrogator  26 . Preferably, the interrogator unit  26  includes an antenna  28 , as well as dedicated transmitting and receiving circuitry, similar to that implemented on the integrated circuit  16 . Generally, the interrogator  26  transmits an interrogation signal or command  27  via the antenna  28 . The device  12  receives the incoming interrogation signal via its antenna  14 . Upon receiving the signal  27 , the device  12  responds by generating and transmitting a responsive signal or reply  29 . The responsive signal  29  typically includes information that uniquely identifies, or labels the particular device  12  that is transmitting, so as to identify any object or person with which the device  12  is associated. The device  12  includes a selectively actuated switch  30  permitting operation of the circuitry only while the switch is actuated. The switch  30  is coupled to the circuitry  16  or between the power source  18  and the circuitry  16 , as will be described below in greater detail. In one embodiment, the switch  30  is a momentary, touch actuated switch. In one embodiment, the switch  30  is a pressable switch which permits the circuitry  16  to provide the signal to identify the device only while the switch  30  is pressed. More particularly, the switch  30  is a momentary, pressure sensitive switch.  
         [0029]    In the illustrated embodiment in FIG. 1, there is no communication between devices  12 . Instead, the devices  12  communicate with the interrogator  26 . Multiple devices  12  can be used in the same field of an interrogator  26  (i.e., within communications range of an interrogator  26 ). Similarly, multiple interrogators  26  can be in proximity to one or more of the devices  12 .  
         [0030]    The radio frequency data communication device  12  can be included in any appropriate housing or packaging. Various methods of manufacturing housings are described in commonly assigned U.S. Pat. application Ser. No. 08/800,037, filed Feb. 13, 1997, and incorporated herein by reference.  
         [0031]    [0031]FIG. 2 shows but one embodiment in the form of a card or badge  19  including the radio frequency data communication device  12 , and a housing  11  including plastic or other suitable material. In one embodiment, the front face of the badge has visual identification features such as graphics, text, information found on identification or credit cards, etc. The switch  30  is supported by the housing  11 .  
         [0032]    [0032]FIG. 3 illustrates but one alternative housing supporting the device  12 . More particularly, FIG. 3 shows a miniature housing  20  encasing the device  12  to define a tag which can be supported by an object (e.g., hung from an object, affixed to an object, etc.). The switch  30  is supported by the housing  20 .  
         [0033]    Although two particular types of housings have been disclosed, the device  12  can be included in any appropriate housing.  
         [0034]    If the power source  18  is a battery, the battery can take any suitable form. Preferably, the battery type will be selected depending on weight, size, and life requirements for a particular application. In one embodiment, the battery  18  is a thin profile button-type cell forming a small, thin energy cell more commonly utilized in watches and small electronic devices requiring a thin profile. A conventional button-type cell has a pair of electrodes, an anode formed by one face and a cathode formed by an opposite face. In an alternative embodiment, the battery  18  comprises a series connected pair of button type cells. Instead of using a battery, any suitable power source can be employed.  
         [0035]    In one embodiment, shown in FIG. 4, the circuitry  16  includes a modulator and is configured to provide a signal responsive to an interrogation by the interrogator  26  (FIG. 1) other than by magnetic coupling. The circuitry  16  includes an active wireless transponder. In other words, the circuitry  16  includes a transponder that transmits other than via magnetic coupling and that receives its power other than via magnetic coupling. For example, in the embodiment shown in FIG. 4, the circuitry  16  includes power terminals  32  and  34 , and the device further includes a battery  36  coupled to the circuitry  16 , via the switch  30 , supplying power to the circuitry  16 . In the embodiment shown in FIG. 4, the switch  30  connects the battery  36  to the circuitry  16  while the switch  30  is pressed and disconnects the battery  36  from the circuitry when the switch is not pressed. In the embodiment shown in FIG. 4, the circuitry  16  includes non-volatile memory so that the contents of the memory are not lost when the battery  36  is disconnected from the circuitry  16  by the switch  30 . The circuitry  16  further includes a transmitter and is configured to provide a responsive signal to the interrogator  26  by radio frequency. More particularly, in the embodiment shown in FIG. 4, the circuitry  16  includes a transmitter, a receiver, and memory such as is described in above-incorporated U.S. patent application Ser. No. 08/705,043. In another embodiment, the circuitry  16  is formed on a printed circuit board, and the switch  30  is added to the printed circuit board as a standard component (e.g., a conventional switch is employed for the switch  30 ). This will allow PC board RFID products to be activated as needed.  
         [0036]    The circuitry  16  further includes antenna terminals  38  and  40  for a first antenna  41 , and antenna terminals  42  and  44  for a second antenna  46 . One of the antennas  41  and  46  is a send or transmit antenna, and the other of the antennas  41  and  46  is a receive antenna. In the illustrated embodiment, one of the antennas  41  and  46  is a dipole antenna, and the other of the antennas  41  and  46  is a loop antenna. In the illustrated embodiment, the dipole antenna is the send antenna, and the loop antenna is the receive antenna. In alternative embodiments, both antennas  41  and  46  are loop antennas or both antennas  41  and  46  are dipole antennas. Further, in alternative embodiments, a single antenna is used for both sending and receiving. The device of FIG. 4 further includes a decoupling capacitor  48  coupled between the terminals  32  and  34 .  
         [0037]    In another embodiment, shown in FIG. 5, the circuitry  16  is configured to provide a signal responsive to an interrogation by the interrogator  26  by magnetic coupling. The circuitry  16  includes an passive wireless transponder. In other words, the circuitry  16  includes a transponder that transmits via magnetic coupling and that receives its power via magnetic coupling. For example, in the embodiment shown in FIG. 5, the circuitry  16  includes power terminals  50  and  52 , and the device further includes a coil  54  coupled to the circuitry  16 , via the switch  30 , supplying power to the circuitry  16 . In the embodiment shown in FIG. 5, the switch  30  connects the coil  54  to the circuitry  16  while the switch  30  is pressed and disconnects the coil  54  from the circuitry when the switch  30  is not pressed. In the embodiment shown in FIG. 5, the circuitry  16  includes non-volatile memory so that the contents of the memory are not lost when the coil  54  is disconnected from the circuitry  16  by the switch  30 . The circuitry  16  further includes a transmitter and is configured to provide a responsive signal to an interrogator by magnetic coupling.  
         [0038]    The circuitry  16  further includes terminals  56  and  58  for a coil  60  which is used for communications to and from an interrogator by magnetic coupling which power is received by coil  54 . In alternative embodiments, separate coils are used for sending and receiving. The device of FIG. 5 further includes a decoupling capacitor  48  coupled between the terminals  50  and  52 .  
         [0039]    A method of manufacturing a device  12  as shown in FIGS.  2 - 4  will now be described, reference being made to FIGS.  6 - 8 .  
         [0040]    The device  12  includes a housing defined in part by a substrate or layer of supportive material  62 . The term “substrate” as used herein refers to any supporting or supportive structure, including, but not limited to, a supportive single layer of material or multiple layer constructions. In the illustrated embodiment, the substrate  62  comprises a polyester film. Other materials are possible. In one embodiment, the polyester film is provided in a roll, using which a number of similar or identical devices are fabricated at the same time and in an assembly line manner. In one embodiment, one or more layers of ink are printed on an inner side of the polyester film facing (after assembly) the back of the device to convey information such as logos and/or company names.  
         [0041]    Conductive ink  64  is formed or applied over the substrate  62  and over any ink. In the illustrated embodiment, the conductive ink  64  comprises PTF (polymer or printed thick film; e.g., a polymer filled with flecks of metal such as silver or copper). One manner of forming or applying the conductive ink on the substrate is to screen print the ink on the substrate through conventional screen printing techniques. The conductive ink forms conductive traces for desired electrical connections with and between electronic components which will be described below. In one embodiment, where the smart card is capable of radio frequency communications, the conductive ink is further used to define the antennas  41  and  46  (see FIGS. 8 and 9). In instances where substrate  62  forms a portion of a larger roll of polyester film material, the printing of conductive ink  64  can take place simultaneously for a number of the to-be-formed devices. A gap  66  is provided along a trace of the conductive ink  64  to define spaced apart ends or terminals  68  and  70  (FIGS. 6 and 7) for the switch  30 . The spaced apart terminals  68  and  70  cause an open circuit unless they are electrically coupled together.  
         [0042]    Conductive epoxy  72  is applied over desired areas (FIG. 8) using a syringe dispenser to assist in component attachment described just below. In one embodiment, solder is employed instead of conductive epoxy. Referring to FIGS. 8 and 9, the battery  36  is provided and mounted on each substrate  62  using the conductive epoxy. The battery  36  is preferably a thin profile battery which includes first and second terminals. More particularly, the battery  36  has a lid or negative terminal, and a can or positive terminal. In an alternative embodiment, multiple batteries are provided (e.g., coupled together in series or parallel).  
         [0043]    An integrated circuit defining the RFID circuitry  16  is provided and mounted on each of the substrates  62  using the conductive epoxy (e.g., picked and placed using surface mounting techniques). An exemplary and preferred integrated circuitry is described in U.S. patent application Ser. No. 08/705,043 incorporated by reference above. The capacitor  48  is similarly provided and mounted.  
         [0044]    The device  12  includes a first or negative battery connection  74  and a second or positive battery connection  76  defined by PTF. The first battery connection is coupled to the integrated circuit by the conductive epoxy, and the second battery connection terminal is coupled to the integrated circuit by the conductive epoxy. In the illustrated embodiment, the battery  36  is placed lid down such that the conductive epoxy makes electrical contact between the negative terminal of the battery and a portion of the first battery connection  74  that extends underneath the lid of the battery in the views shown in FIGS. 8 and 9.  
         [0045]    The battery has a perimetral edge which is disposed adjacent the second battery connection  76 . Conductive epoxy is dispensed relative to battery perimetral edge and electrically connects the perimetral edge with an adjacent arcuate portion of the second battery connection  76 . In the illustrated embodiment, the perimetral edge defines the can of the battery, such that the conductive epoxy connects the positive terminal of the battery to the battery connection terminal  76 .  
         [0046]    The conductive epoxy is then cured.  
         [0047]    Subsequently, encapsulating epoxy material is provided to encapsulate the substrates, to cover the integrated circuits and batteries, and conductive traces and to define a second housing portion. After application and curing of such epoxy, the a suitable separation or singulation process takes place if multiple devices were formed simultaneously.  
         [0048]    At any time after the conductive ink  64  is applied and before the encapsulating epoxy is provided, an insulating ring  78  is placed over a certain portion of the PTF  64 . The insulating ring  78  has a periphery  80  and is positioned such that the periphery  80  circumscribes the ends  68  and  70  (see FIG. 7). A diaphragm  82  having a periphery  84  corresponding in size and shape to the periphery  80  of the insulating ring  78  is placed over the insulating ring  78  such that the insulating ring spaces the diaphragm  82  from the ends  68  and  70 . The diaphragm  82  has a conductive face  86  facing the ends  68  and  70 . Thus, after construction of the device  12 , pushing on an area  88  of the flexible substrate  62  causes the ends  68  and  70  to move into contact with the conductive face  86  of the diaphragm  82 , thus causing an electrical connection to be made between the ends  68  and  70 . The diaphragm  82  does not move away from the ends  68  and  70  because the encapsulant is positioned above the diaphragm  82 , and the encapsulant is substantially rigid.  
         [0049]    [0049]FIGS. 8 and 9 illustrate alternative possible locations for the gap  66  and thus for the switch  30 . In the embodiment of FIG. 8, the gap  66  is provided along a battery connection. Thus, unless the switch  30  is pressed and held, no power is available to the circuitry  16 . The embodiment of FIG. 8 can be used where the circuitry  16  includes non-volatile memory or where no important information is lost if power is disconnected. In the embodiment of FIG. 9, the gap  66  is not provided along a battery connection. Instead, the embodiment of FIG. 9 is one to be used when the circuitry  16  does not employ non-volatile memory. In the embodiment of FIG. 9, the switch is provided between pins of the circuitry  16  used to set a digital flag described above.  
         [0050]    In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.