Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
1999-03-13
2001-04-10
Trieu, Van T. (Department: 2736)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S572100, C340S568100
Reexamination Certificate
active
06215401
ABSTRACT:
FIELD OF THE INVENTION
The field of the invention is the field of Radio Frequency (RF) transponders (RF Tags) which receive RF electromagnetic radiation from a base station and send information to the base station by modulating the load of an RF antenna.
BACKGROUND OF THE INVENTION
RF Tags can be used in a multiplicity of ways for locating and identifying accompanying objects, items, animals, and people, whether these objects, items, animals, and people are stationary or mobile, and transmitting information about the state of the of the objects, items, animals, and people. It has been known since the early 60's in U.S. Pat. No. 3,098,971 by R. M. Richardson, that electronic components on a transponder could be powered by radio frequency (RF) power sent by a “base station” at a carrier frequency and received by an antenna on the tag. The signal picked up by the tag antenna induces an alternating current in the antenna which can be rectified by an RF diode and the rectified current can be used for a power supply for the electronic components. The tag antenna loading is changed by something that was to be measured, for example a microphone resistance in the cited patent. The oscillating current induced in the tag antenna from the incoming RF energy would thus be changed, and the change in the oscillating current led to a change in the RF power radiated from the tag antenna. This change in the radiated power from the tag antenna could be picked up by the base station antenna and thus the microphone would in effect broadcast power without itself having a self contained power supply. In the cited patent, the antenna current also oscillates at a harmonic of the carrier frequency because the diode current contains a doubled frequency component, and this frequency can be picked up and sorted out from the carrier frequency much more easily than if it were merely reflected. Since this type of tag carries no power supply of its own, it is called a “passive” tag to distinguish it from an active tag containing a battery. The battery supplies energy to run the active tag electronics, but not to broadcast the information from the tag antenna. An active tag also changes the loading on the tag antenna for the purpose of transmitting information to the base station.
The “rebroadcast” or “reflection” of the incoming RF energy at the carrier frequency is conventionally called “back scattering”, even though the tag broadcasts the energy in a pattern determined solely by the tag antenna and most of the energy may not be directed “back” to the transmitting antenna.
In the 70's, suggestions to use tags with logic and read/write memories were made. In this way, the tag could not only be used to measure some characteristic, for example the temperature of an animal in U.S. Pat. No. 4,075,632 to Baldwin et. al., but could also identify the animal. The antenna load was changed by use of a transistor. A transistor switch also changed the loading of the transponder in U.S. Pat. No. 4,786,907 by A. Koelle.
Prior art tags have used electronic logic and memory circuits and receiver circuits and modulator circuits for receiving information from the base station and for sending information from the tag to the base station.
The continuing march of semiconductor technology to smaller, faster, and less power hungry has allowed enormous increases of function and enormous drop of cost of such tags. Presently available research and development technology will also allow new function and different products in communications technology.
Prior art tags have generally been made from discrete components mounted on printed circuit boards. The antennas have been formed by etching material from the copper of the printed circuit board. Some prior art tags have been formed from mounting the silicon chips and bonded antennas on flexible plastic substrates. The components, antenna wire, and connections must be protected from the environment in all cases. Some prior art tags mounted on flexible substrates are protected by laminating a cover on to the flexible substrate to make a hermetic seal. Such sealing methods are unsatisfactory, as the seal may be broken if the tag is bent or abraded in use. In addition, the extra material for the lamination is expensive.
RELATED PATENTS AND APPLICATIONS
Related U.S. Pat. Nos. assigned to the assignee of the present invention include:5,521,601; 5,528,222; 5,538,803; 5,550.547; 5,552,778; 5,554,974; 5,563,583; 5,565,847; 5,606,323; 5,635,693; 5,673,037; 5,680,106;5,682,143; 5,729,201; 5,729,697;5,736,929; 5,739,754; 5,767,789; 5,777,561; 5,786,626; 5,812,065; 5,821,859; and 5,826,328. U.S. patent applications assigned to the assignee of the present invention include: application No. 08/626,820, filed: Apr. 3, 1996, entitled “Method of Transporting RF Power to Energize Radio Frequency Transponders”, by Heinrich, Zai, et al.; application Ser. No. 08/694,606 filed Aug. 9, 1996 entitled RFID System with Write Broadcast Capability by Cesar et al. ; application Ser. No. 08/681,741 filed Jul. 29, 1996 entitled RFID Transponder with Electronic Circuitry Enabling and Disabling Capability, by Heinrich, Goldman et al.; and application Ser. No. 09/153,617
1
filed Sep. 25, 1998, entitled RFID Interrogator Signal Processing System for Reading Moving Transponder, by Zai et al. The above identified U.S. Patents and U.S. Patent applications are hereby incorporated by reference.
OBJECTS OF THE INVENTION
It is an object of the invention to produce an RE transponder which can be made at low cost. It is a further object of the invention to produce an RF transponder which can be used at high frequencies. It is a further object of the invention to provide an RF transponder having a protective coating which protects the transponder from the deleterious effects due to bending and abrading.
SUMMARY OF THE INVENTION
The present invention is an RF tag having a non laminated coating for protecting the semiconductor chip, antenna, and chip antenna connections, and a method for applying the non-laminated coating.
REFERENCES:
patent: 5091447 (1992-02-01), Lomasney
patent: 5242715 (1993-09-01), Schoen et al.
patent: 5406263 (1995-04-01), Tuttle
patent: 5448110 (1995-09-01), Tuttle et al.
patent: 5487926 (1996-01-01), Kuribayashi et al.
patent: 5682143 (1997-10-01), Brady et al.
patent: 5961923 (1999-10-01), Nova et al.
Brady Michael J.
Moskowitz Paul A.
Hodgson R. T.
Intermec IP Corp.
Trieu Van T.
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