US 20060097849 A1
The present invention relates to wireless communication devices and methods of forming and operating the same. The present invention provides a wireless communication device including a substrate having a support surface, wireless communication circuitry upon the support surface of the substrate, at least one antenna electrically coupled with the wireless communication circuitry, a conductive layer configured to interact with the antenna, and an insulative layer intermediate the conductive layer and the antenna. A method of forming a wireless communication device includes providing a substrate having a support surface, forming an antenna upon the support surface, conductively coupling wireless communication circuitry with the antenna, forming an insulative layer over at least a portion of the antenna, and providing a conductive layer over at least a portion of the insulative layer.
1. A wireless communication device comprising:
a substrate having a support surface;
wireless communication circuitry upon the support surface of the substrate;
at least one antenna electrically coupled with the wireless communication circuitry;
a conductive layer configured to interact with the at least one antenna; and
an insulative layer intermediate the conductive layer and the at least one antenna.
2. The wireless communication device according to
3. The wireless communication device according to
4. The wireless communication device according to
5. The wireless communication device according to
6. The wireless communication device according to
7. The wireless communication device according to
8. The wireless communication device according to
9. The wireless communication device according to
10. The wireless communication device according to
11. The wireless communication device according to
12. The wireless communication device according to
13. The wireless communication device according to
14. The wireless communication device according to
15. A remote intelligent communication device comprising:
a substrate having a support surface;
a conductive trace formed upon the support surface and including at least one antenna configured to at least one of transmit and receive wireless communication signals;
transponder circuitry bonded to the support surface and electrically coupled with the conductive trace;
a first encapsulant layer enveloping the transponder circuitry, the at least one antenna, and at least a portion of the substrate;
a conductive layer positioned upon the first encapsulant layer to interact with the at least one antenna; and
a second encapsulant layer over the conductive layer and forming a substantially solid housing with the substrate and the first encapsulant layer.
16. The remote intelligent communication device according to
17. The remote intelligent communication device according to
18. The remote intelligent communication device according to
19. The remote intelligent communication device according to
20. The remote intelligent communication device according to
The present invention relates to wireless communication devices and methods of forming and operating the same.
Electronic identification systems typically comprise two devices which are configured to communicate with one another. Preferred configurations of the electronic identification systems are operable to provide such communications via a wireless medium.
One such configuration is described in U.S. patent application Ser. No. 08/705,043, filed Aug. 29, 1996, assigned to the assignee of the present application and incorporated herein by reference. This application discloses the use of a radio frequency (RF) communication system including communication devices. The communication devices include interrogator and a transponder such as a tag or card.
The communication system can be used in various identification and other applications. The interrogator is configured to output a polling signal which may comprise a radio frequency signal including a predefined code. The transponders of such a communication system are operable to transmit an identification signal responsive to receiving an appropriate command or polling signal. More specifically, the appropriate transponders are configured to recognize the predefined code. The transponders receiving the code subsequently output a particular identification signal which is associated with the transmitting transponder. Following transmission of the polling signal, the interrogator is configured to receive the identification signals enabling detection of the presence of corresponding transponders.
Such communication systems are useable in identification applications such as inventory or other object monitoring. For example, a remote identification device is attached to an object of interest. Responsive to receiving the appropriate polling signal, the identification device is equipped to output an identification signal. Generating the identification signal identifies the presence or location of the identification device and article or object attached thereto.
Such identification systems configured to communicate via radio frequency signals are susceptible to incident RF radiation. Such RF radiation can degrade the performance of the identification system. For example, application of transponders to objects comprising metal may result in decreased or no performance depending on the spacing of the transponder antenna to the nearest metal on the object.
Therefore, there exists a need to reduce the effects of incident RF radiation upon the operation of communication devices of an electronic identification system.
According to one embodiment of the invention, a wireless communication device is provided which includes a substrate, communication circuitry, antenna and a conductive layer configured to interact with the antenna. Some embodiments of the wireless communication devices include remote intelligent communication devices and radio frequency identification devices.
According to additional aspects of the present invention, methods of forming a wireless communication device and a radio frequency identification device are provided. The present invention also provides methods of operating a wireless communication device and a radio frequency identification device.
The conductive layer is configured to act as a ground plane in one embodiment of the invention. The ground plane shields some signals from the antenna while reflecting other signals toward the antenna. The ground plane also operates to reflect some of the signals transmitted by the device. The conductive layer is preferably coupled with a terminal of a power source within the communication device. Such coupling provides the conductive layer at a reference voltage potential.
The communication circuitry comprises transponder circuitry in accordance with other aspects of the present invention. The transponder circuitry is configured to output an identification signal responsive to receiving a polling signal from an interrogator. Certain disclosed embodiments provide a processor within the communication devices configured to process the received polling signal. The processor and communication circuitry may be implemented in an integrated circuit.
The wireless communication device is provided within a substantially solid, void-free housing in accordance with one aspect of the present invention. Such a housing comprises plural encapsulant layers and a substrate.
Preferred embodiments of the invention are described below with reference to the following accompanying drawings.
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).
This description of the present invention discloses embodiments of various wireless communication devices. The wireless communication devices are fabricated in card configurations (which include tags or stamps) according to first and second aspects of the present invention. The embodiments are illustrative and other configurations of a wireless communication device according to the present invention are possible. Certain embodiments of the wireless communication device according to the invention comprise radio frequency identification devices (RFID) and remote intelligent communication devices (RIC).
The communication system 12 shown in
Substrate 18 provides a first or lower portion of a housing for the wireless communication device 10 and defines an outer periphery 21 of the device 10. Substrate 18 includes a plurality of peripheral edges 17.
A support surface 20 is provided to support components and circuitry formed in later processing steps upon substrate 18. In embodiments wherein at least one ink layer 19 is provided, support surface 20 comprises an upper surface thereof as shown in
A patterned conductive trace 30 is formed or applied over the substrate 18 and atop the support surface 20. Conductive trace 30 is formed upon ink layer 19, if present, or upon substrate 18 if no ink layer is provided. A preferred conductive trace 30 comprises printed thick film (PTF). The printed thick film comprises silver and polyester dissolved into a solvent. One manner of forming or applying the conductive trace 30 is to screen or stencil print the ink on the support surface 20 through conventional screen printing techniques. The printed thick film is preferably heat cured to flash off the solvent and UV cured to react UV materials present in the printed thick film.
The conductive trace 30 forms desired electrical connections with and between electronic components which will be described below. In one embodiment, substrate 18 forms a portion of a larger roll of polyester film material used to manufacture multiple devices 10. In such an embodiment, the printing of conductive trace 30 can take place simultaneously for a number of the to-be-formed wireless communication devices.
The illustrated conductive trace 30 includes an electrical connection 28, a first connection terminal 53 (shown in phantom in
Other antenna constructions are possible. In particular, both transmit and receive operations are implemented with a single antenna in alternative embodiments of the present invention. Both antennas 32, 34 preferably extend or lie within the confines of peripheral edges 17 and outer periphery 21 and define a plane (shown in
One embodiment of a wireless communication device 10 includes a power source 52, integrated circuit 54, and capacitor 55. Power source 52, capacitor 55, and integrated circuit 54 are provided and mounted on support surface 20 and supported by substrate 18. The depicted power source 52 is disposed within transmit antenna 32 of wireless communication device 10. Capacitor 55 is electrically coupled with loop antenna 32 and integrated circuit 54 in the illustrated embodiment.
Power source 52 provides operational power to the wireless communication device 10 and selected components therein, including integrated circuit 54. In the illustrated embodiment, power source 52 comprises a battery. In particular, power source 52 is preferably a thin profile battery which includes first and second terminals of opposite polarity. More particularly, the battery has a lid or negative (i.e., ground) terminal or electrode, and a can or positive (i.e., power) terminal or electrode.
Conductive epoxy is applied over desired areas of support surface 20 using conventional printing techniques, such as stencil or screen printing, to assist in component attachment described just below. Alternately, solder or another conductive material is employed instead of conductive epoxy. The power source 52 is provided and mounted on support surface 20 using the conductive epoxy. Integrated circuit 54 and capacitor 55 are also provided and mounted or conductively bonded on the support surface 20 using the conductive epoxy. Integrated circuit 54 can be mounted either before or after the power source 52 is mounted on the support surface 20.
Integrated circuit 54 includes suitable circuitry for providing wireless communications. For example, in one embodiment, integrated circuit 54 includes a processor 62, memory 63, and wireless communication circuitry or transponder circuitry 64 (components 62, 63, 64 are shown in phantom in
One embodiment of transponder circuitry 64 includes a transmitter and a receiver respectively operable to transmit and receive wireless electronic signals. In particular, transponder circuitry 64 is operable to transmit an identification signal responsive to receiving a polling signal from interrogator 14. In the described embodiment, processor 62 is configured to process the received polling signal to detect a predefined code within the polling signal. Responsive to the detection of an appropriate polling signal, processor 62 instructs transponder circuitry 64 to output an identification signal. The identification signal contains an appropriate code to identify the particular device 10 transmitting the identification signal in certain embodiments. The identification and polling signals are respectively transmitted and received via antennas 32, 34 of the device 10.
First and second connection terminals 53, 58 are coupled to the integrated circuit 54 by conductive epoxy in accordance with a preferred embodiment of the invention. The conductive epoxy also electrically connects the first terminal of the power source 52 to the first connection terminal 53. In the illustrated embodiment, power source 52 is placed lid down such that the conductive epoxy makes electrical contact between the negative terminal of the power source 52 and the first connection terminal 53.
Power source 52 has a perimetral edge 56, defining the second power source terminal, which is provided adjacent second connection terminal 58. In the illustrated embodiment, perimetral edge 56 of the power source 52 is cylindrical, and the connection terminal 58 is arcuate and has a radius slightly greater than the radius of the power source 52, so that connection terminal 58 is closely spaced apart from the edge 56 of power source 52.
Subsequently, conductive epoxy is dispensed relative to perimetral edge 56 and electrically connects perimetral edge 56 with connection terminal 58. In the illustrated embodiment, perimetral edge 56 defines the can of the power source 52. The conductive epoxy connects the positive terminal of the power source 52 to connection terminal 58. The conductive epoxy is then cured.
An exemplary encapsulant is a flowable encapsulant. The flowable encapsulant is applied over substrate 18 and subsequently cured following the appropriate covering of the desired components. In the illustrated embodiment, such encapsulant constitutes a two-part epoxy including fillers, such as silicon and calcium carbonate. The preferred two-part epoxy is sufficient to provide a desired degree of flexible rigidity. Such encapsulation of wireless communication device 10 is described in U.S. patent application Ser. No. 08/800,037, filed Feb. 13, 1997, assigned to the assignee of the present application, and incorporated herein by reference.
Other encapsulant materials of insulative layer 60 can be used in accordance with the present invention. In addition, the thickness of insulative layer 60 can be varied. Using alternative encapsulant materials and the adjusting of the dimensions of insulative layer 60 alter the dielectric characteristics (i.e., dielectric constant) of layer 60.
In embodiments where one of connections 26, 26 a is provided (alternate connection 26 a is shown in
The thickness of insulative layer 60 defines the distance between a conductive layer 22 (described below) and antennas 32, 34, provided adjacent opposing sides of layer 60. The thickness of insulative layer 60 is chosen as a function of the dielectric constant of the encapsulant and the desired frequency for communication.
After provision of insulative layer 60, a conductive layer 22 is formed or applied over the dielectric surface 65 thereof. Conductive layer 22 includes peripheral edges 61. Preferably, conductive layer 22 covers or is provided over the entire insulative dielectric surface 65. Alternatively, conductive layer 22 is patterned to cover predefined portions of dielectric surface 65. In embodiments wherein conductive layer 22 is patterned, the layer 22 is preferably formed at least over antennas 32, 34. More specifically, the respective peripheral edges 37, 38 of antennas 32, 34 are provided within the confines of the peripheral edges 61 of conductive layer 22.
Conductive layer 22 formed upon dielectric surface 65 is preferably substantially planar. In addition, conductive layer 22 is substantially parallel to the plane 33 defined by antennas 32, 34, as well as dielectric surface 65.
In one embodiment, conductive layer 22 comprises a stencil printed polymer thick film (PTF). The polymer thick film is typically 70-73% overfilled. In an alternative embodiment, conductive layer 22 is a conductive epoxy comprising approximately 70% metal. Further alternatively, conductive layer 22 comprises copper or gold foil laminated upon the dielectric surface 65 of insulative layer 60. In still another embodiment of the present invention, metal such as gold is sputtered upon dielectric surface 65 of insulative layer 60 to form conductive layer 22.
Conductive layer 22 can be configured to operate as a ground plane and interact with antennas 32, 34. In particular, conductive layer 22 can be used to form a radio frequency (RF) shield. Inasmuch as the preferred embodiment of communication device 10 communicates via wireless signals, it is desired to reduce or minimize interference, such as incident RF radiation. Conductive layer 22 interacts with antennas 32, 34 to improve the RF operation of wireless communication device 10.
In one embodiment, conductive layer 22 operates to shield some wireless electronic signals from the receive antenna 34 and reflect other wireless electronic signals toward the antenna 34. Conductive layer 22 includes a first side, which faces away from antennas 32, 34 (opposite surface 65) and a second side, which faces antennas 32, 34 (adjacent surface 65). Electronic signals received on the first side of the conductive layer 22 are shielded or blocked by layer 22 from reaching the antennas 32, 34. Electronic signals received on the second side of the conductive layer 22, which pass by or around antennas 32, 34, are reflected by layer 22.
Some of the wireless communication signals transmitted by communications device 10 via antenna 32 are reflected by conductive 8 layer 22. In particular, wireless signals transmitted from antenna 32 which strike the second side of conductive layer 22 are reflected thereby.
Such shielding and reflecting by conductive layer 22 provides a highly directional wireless communication device 10. The provision of conductive layer 22 within wireless communication device 10 results in robust wireless communications with interrogator 14 and provides increased reliability.
The conductive layer 22 is electrically connected with power source 52 in the illustrated embodiments of the present invention. Conductive layer 22 can be electrically coupled with either the positive or negative terminal of power source 52. Coupling of conductive layer 22 with one of the terminals of power source 52 provides layer 22 at the voltage potential of the respective terminal.
In one embodiment, conductive layer 22 is electrically coupled with the ground (i.e., negative) terminal of power source 52 through the integrated circuit 54. Referring specifically to
Coupling of one of the power terminals of power source 52 and ground plane/conductive layer 22 provides layer 22 at a common reference voltage. In particular, electrically connecting ground plane/conductive layer 22 and the ground terminal of power source 52 via electrical connections 26, 28 electrically grounds layer 22. Alternatively, ground plane/conductive layer 22 is coupled with the power electrode of power source 52 via electrical connections 26, 28 in other embodiments of the invention. Coupling ground plane/conductive layer 22 with the power electrode of power source 52 provides layer 22 at the positive potential of power source 52.
Pin 26 is coupled directly with one of the terminals of power source 52 in other embodiments of the invention (not shown), thereby bypassing integrated circuit 54. Alternatively, no electrical connection is made to ground plane/conductive layer 22. In such an embodiment, ground plane/conductive layer 22 is insulated and the voltage of layer 22 is permitted to float.
Connections 26, 26 a may be formed at positions other than those illustrated in the depicted embodiments of device 10. In particular, connections 26, 26 a may be provided at any appropriate location to provide electrical coupling of a terminal of power source 52 and conductive layer 22.
Second encapsulant layer 66 may comprise the two-part encapsulant utilized to form insulative first encapsulant layer 60. Following the provision of second encapsulant layer 66 upon conductive layer 22, the encapsulant is subsequently cured forming a substantially void-free housing 27 or solid mass with substrate 18 and first encapsulant layer 60. In one embodiment, housing 27 of wireless communication device 10 has a width of about 3.375 inches, a height of about 2.125 inches, and a thickness less than or equal to about 0.0625 inches.
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.