Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
1999-09-01
2001-07-03
Mullen, Thomas (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C174S050510, C257S788000
Reexamination Certificate
active
06255949
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates in general to radio frequency identification (RFID) devices, and more particularly to a high temperature RFID tag.
BACKGROUND OF THE INVENTION
RFID systems are well known in the art. Such systems include relatively large packages containing battery powered transmission/receiving circuitry, such as the identification system disclosed in U.S. Pat. No. 4,274,083, to passive systems in which the transceiver receives its power from the base station or interrogator, such as the identification system disclosed in U.S. Pat. No. 4,654,658.
A typical RFID system is made up of reusable tags fixed to or embedded in product carriers, antennas that interrogate the tags via a RF link and a controller. The host (or computer) system interfaces with the controller and directs the interrogation of the tags.
RFID tags provide effective means of identifying, monitoring and controlling materials in a closed loop process. In the factory, tags are employed as the transport mechanism between “islands of automation,” providing a record of each process which can be acted upon immediately or downloaded later for analysis.
The tags can be powered by an internal battery (i.e., an “active” tag) or by inductive coupling (i.e., a “passive” tag). Passive tags have zero maintenance and virtually unlimited life. The life span of an active tag is, however, limited by the lifetime of the battery, although some tags offer replaceable batteries.
RFID tags are packaged in a variety of forms and are fastened by a multitude of means. The tags are typically encapsulated for durability against shock, fluids, dust or dirt. Although such tags are immune to most environmental factors , they can, and in many instances will be, adversely affected by high temperature environments.
It is, therefore, an object of the present invention to provide a RFID tag having the capability of operating over a broad range of temperatures.
It is another object of the invention to provide a substantially flexible RFID tag which is capable of operation in harsh, high temperature factory environments.
SUMMARY OF THE INVENTION
The high temperature RFID tag of the present invention has a substantially enhanced survival temperature in the range of −40° C. to 300° C. The tag also has a unique operating temperature in the range of −18° C. to 135° C.
In accordance with the objects and advantages of the present invention, the high temperature RFID tag comprises a housing and substrate assembly, the housing having a base and a top, the base and the top forming a chamber therein, the housing comprising a first thermally resistant material; the substrate assembly including a substrate comprising a second thermally resistant material, the substrate including an integrated circuit, the substrate assembly being disposed in the chamber; the housing and substrate assembly jointly having a survival temperature range of approximately 220° C. to 300° C. and an operating temperature range of approximately −18° C. to 135° C.; the housing and substrate assembly being capable of exposure to cyclic changes in temperature to and between the operating temperature range and the survival temperature range without substantially affecting the intended functions of the tag. According to the invention, the first and second thermally resistant materials can also comprise substantially flexible thermal resistant materials.
In an additional embodiment of the invention, the high temperature RFID tag comprises a substrate assembly, the substrate assembly including a substrate having an integrated circuit disposed thereon, the substrate comprising a substantially flexible first thermally resistant material, and a high temperature encapsulant disposed on a first side of the substrate, the substrate assembly having a survival temperature in the range of −40° C. to 300° C.
REFERENCES:
patent: 5574470 (1996-11-01), deVall
patent: 5973599 (1999-10-01), Nicholson et al.
patent: 6037879 (2000-03-01), Tuttle
Monahan Brian
Nicholson Mark
Escort Memory Systems
Francis Law Group
Mullen Thomas
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