Communications: electrical – Selective – Interrogation response
Reexamination Certificate
1997-03-05
2001-01-09
Zimmerman, Brian (Department: 2735)
Communications: electrical
Selective
Interrogation response
Reexamination Certificate
active
06172596
ABSTRACT:
BACKGROUND OF THE INVENTION
The field of the invention is the field of Radio Frequency (RF) or Microwave communication of data and control information between a Base Station and a plurality of remotely located RF Transponders (Tags).
Identification and Location Transponders (Tags) such as radio frequency (RF) Tags have been used in a multiplicity of ways for locating and identifying accompanying objects and transmitting information about the state of the object. It has been known since the early 60's that electronic components could be powered by RF power received by an antenna and rectified by an RF diode. In the 70's, suggestions to use tags with read/write memories which back scattered the incoming RF were made. In the 70's suggestions were also made to convert part of the incoming RF radiation to a harmonic of the incoming signal, and rebroadcast this new frequency to communicate the tag information. Presently available technology uses a number of different systems, each having tags and base stations which use different kinds of tags using different frequencies, different read and write codes, tags with electronics powered with batteries, tags which transmit a different carrier frequency than does the base station, tags which communicate by changing magnetic field, by sound and ultrasound fields, etc.
Prior art systems send power from the base station to energize the tags, and the tags modulate the loading on the tag antennas to communicate the information contained in the tag memory, or the information measured by the tag, back to the base station.
Prior art systems can interrogate the tags if more than one tag is in the field. U.S. Pat. No. 5,214,410, hereby incorporated by reference, teaches a method for a base station to communicate with a plurality of Tags.
The prior art teaches a method to interrogate a plurality of tags in the field of the base station. The tags are energized, and send a response signal at random times. If the base station can read a tag unimpeded by signals from other tags, the base station interrupts the interrogation signal, and the tag which is sending and has been identified, shuts down. The process continues until all tags in the field have been identified. If the number of possible tags in the field is large, this process can take a very long time. The average time between the random responses of the tags must be set very long so that there is a reasonable probability that a tag can communicate in a time window free of interference from the other tags.
The continuing march of semiconductor technology to smaller, faster, and less power hungry circuits 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. There is no technology in place to handle the many different products which could be allowed by the technology.
Presently, each system of tags has matching base stations, and thus the tags of one system can not communicate information to a base station of another system. Within any given system, the tags have the same physical and software characteristics, i.e. the number of bits of read/write memory is the same, and the information stored on the tag is stored the same unstructured way for every tag in the system.
RELATED APPLICATIONS
Copending patent applications assigned to the assignee of the present invention Ser. No. 08/303,965 filed Sep. 9, 1994 entitled RF Group Select Protocol, by Chan et. al., (now U.S. Pat. No. 5,673,037 issued Sep. 30, 1997); serial No. 08/304,340 filed Sept. 9, 1994 entitled Multiple Item RF ID protocol, by Chan et. al., (now U.S. Pat. No. 5,550,5477 issued Aug. 27, 1996); Ser. No. 08/521,898 filed Aug. 31, 1995 entitled Diode Modulator for RF Transponder by Friedman et al. (now U.S. Pat. No. 5,606,323 issued Feb. 25, 1997 issued Sep. 30, 1997); Ser. No. 08/694,606 submitted Aug. 9, 1996 entitled RFID System with Broadcast Capability by Cesar et al.; and Ser. No. 08/1681,741 submitted Jul. 29, 1996 entitled RFID transponder with Electronic Circuitry Enabling and Disabling Capabilithy, by Heinrich et al. are hereby incorporated by reference. The communication time per tag generally increases with the number of tags in the field of the base station. The communication time per tag can be reduced if a particular group of tags can be selected from the plurality of tags in the field, so that the tags in the particular group can be interrogated and then shut off.
OBJECTS OF THE INVENTION
It is an object of the invention to provide a system of base stations and different types of RF tags which make efficient use of tag memory.
It is an object of the invention to provide tags having different tag types for different software types of tags.
It is an object of the invention to provide tags having different tag types for different hardware types of tags.
It is an object of the invention to provide an RF tag which may be used for different applications in succession.
It is an object of the invention to provide base stations for different software types of tags.
It is an object of the invention to provide a method of using different types of RF tags.
It is an object of the invention to provide a hierarchical system of types of RF tags.
SUMMARY OF THE INVENTION
The present invention comprises a system of one or more base stations which can communicate information to and receive information from a plurality of tag types using RF electromagnetic radiation. The present invention comprises tag types which differ in either or both hardware and software configuration. The present invention comprises a series of hardware and software tag types for differing purposes. Tags with different software types differ in the layout of information contained in the tag memory. The present invention requires that each tag carry a tag type code or number in the tag memory. In the most preferred embodiment, a computer attached to the base station determines the layout of information in the memory of a tag of a particular tag type on the basis of the tag type number. The base station computer also determines the hardware capability of the tag on the basis of the tag type number. In a preferred embodiment, the tag carries a directory with information on the layout of information in the tag memory.
REFERENCES:
patent: 4827395 (1989-05-01), Anders
patent: 5008661 (1991-04-01), Raj
patent: 5214410 (1993-05-01), Verster
patent: 5481519 (1996-01-01), Hosoya
patent: 5887176 (1999-03-01), Griffith
Cesar Christian Lenz
Cofino Thomas Anthony
Goldman Kenneth Alan
Greene Sharon Louise
Heinrich Harley Kent
Intermec IP Corp.
O'Melveny & Myers LLP
Zimmerman Brian
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