Registers – Coded record sensors – Particular sensor structure
Reexamination Certificate
2002-01-30
2004-03-23
Le, Thien M. (Department: 2876)
Registers
Coded record sensors
Particular sensor structure
C235S455000
Reexamination Certificate
active
06708881
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention is directed, in general, to a SAW identification tag reader and, more specifically, to a reader for use with surface acoustic wave (SAW) identification tags having enhanced data content and to methods of operating and manufacturing the same.
BACKGROUND OF THE INVENTION
Familiar to all are the bar codes and magnetic strips employed by businesses to perform identification functions and the various devices used to read them. Generally, magnetic strips are read by swiping a card with the strip on it, such as a credit card, through a reader. Magnetic strips can also read by contact or proximity devices where the card, such as a parking or access card, is placed on or held close to the reader. Bar codes are most generally read by using a “light gun” to read the code and identify the item associated with that particular code. The main reason bar codes and magnetic strips are the identification systems of choice is that they are very cheap.
The applications for which bar codes and magnetic strips are useful is limited, however, by the relatively small amount of data they can encode and their inherent readability limitations. One such readability limitation is the range at which they can be used. Both are short range systems that require the reader to contact or be very close (a few centimeters, at most) to the bar code or magnetic strip, as the case may be, in order to decode data. They are also limited by the fact that no obstruction can be between the reader and the bar code or magnetic strip for the reader to accurately decode data. The orientation of the reader relative to the bar code or magnetic strip can also be a significant readability problem. If the reading device is not properly aligned or is held at an incorrect angle, the encoded information can not be read. As a result of these problems, each individual read operation requires manual scanning by a human operator if high read accuracy is needed. The various limitations of bar codes and magnetic strips have prevented their use in a wide range of applications for machine readable tags that need highly reliable and totally automated reading at read ranges up to several meters.
The radio frequency identification (“RFID”) tag is another prior art identification device. As the name suggests, when RFID tags are interrogated they reflect or retransmit a radio signal that returns encoded identification information. RFID tags have many uses, ranging from the collection of highway and bridge tolls to being embedding in objects to circumvent counterfeiters. An advantage of RFID tags over magnetic devices and bar codes is that they can generally be sensed at a somewhat longer distance without having as significant line-of-sight and orientation problems that are evidenced in bar code and magnetic strip systems. Although RFID tags have a longer reliable range than the ubiquitous magnetic strip and bar code systems, the range at which they can reliably operate is still a limiting factor.
Prior art RFID tag devices are of two basic types; those that contain a microchip and those that do not. There is a radical difference in cost and performance between the two types; to such an extent that they rarely compete with one another as to type of use. As a general rule, chip tags cost more by have a larger data capacity than chipless tags. Chip tags, for example, are usually not available below a unit cost of about one dollar each when ordered in a quantity of less than one million; whereas many chipless tags are projected to cost less than 20 cents each, even when ordered in quantities of one hundred thousand.
Chip tags are by far the most popular. A chip tag consists of four elements or features: (1) a computer microchip; (2) circuits for converting radio signals to computer data signals and back to radio signals; (3) an antenna; and (4) a means for providing DC power to the chip circuitry. In low cost RFID chip tags, the first two features are often partially or totally integrated into a single microchip, which integration requires certain compromises in tag performance (read range, number of bits, etc.). This combination of features also leads to certain integrated circuit (IC) cost and/or design compromises to accommodate both digital and radio frequency circuitry on a single IC. The impact of these design compromises can be partially compensated for by use of low radio frequency (RF) operating frequencies that, in turn, lead to rather large and expensive antennas.
The most daunting problem with chip tags is the need for DC power for the chip circuitry. The combination of environmental issues coupled with severe constraints on cost, size and weight usually requires that the tag not have a battery or other on-board power source. The only generally useable solution is to obtain DC power by converting RF power received from the tag reader signal into DC power within the tag. Those skilled in the pertinent art term tags without a battery or other power source as “passive” tags, while those that contain a battery or other source are termed as “active” tags. The passive method of providing DC power to a chip tag requires a more efficient tag antenna (i.e., larger size and cost) and higher transmitted power levels from the reader. It also requires added components which will either add to the cost of the microchip or to the cost of the tag for the required extra electrical components in the tag, which additional components will also result in an increased tag size. The most important limitation of passive powered chip tags, however, is the severe restriction on the read range of the tag because a signal that is sufficiently strong to power the tag only extends a short distance from the tag reader antenna. Thus, while chip tags have the dominate share of the RFID market, the high cost and limited read range combine to prevent chip tags from replacing either bar codes or magnetic strips in any significant manner.
“Chipless” RFID tags do not contain a microchip but, instead, rely on magnetic materials or transistorless thin film circuits to store data. A major advantage of chipless RFID tags is their relatively low cost. The disadvantages of chipless tags include that they are range limited (several centimeters at the most) and only contain limited amounts of information. The severity of these problems has prevented their market acceptance in spite of their low cost potential.
In the year 2000, the current global market for conventional RFID systems and services is in the order of 500 million U.S. dollars. This market is largely for chip tags that typically cost from about one dollar to tens of dollars each. While chipless tags are not selling well, they have generated great interest from a number of potential users because of their low cost potential. A huge gap exists in the automatic identification market between the very low cost bar codes and the higher performing RFID chip tags. The overall market is clamoring for a technical solution to fill that gap. The critical characteristics of the new automatic identification technology to fill this gap are: (1) a cost of between one cent and ten cents per tag when manufactured in high quantities; (2) reliable reading without the need for manual scanning by a human operator; (3) reliable reading without a line of sight between the tag and tag reader (i.e., reliable reading even if the tag is scratched, or covered with dirt, or on the wrong side of the package, etc.); (4) a reliable read range of at least one to two meters; and (5) a tag data capacity of roughly 100 bits. Such tags are of vital interest to postal authorities, airlines and airports, mass transit authorities, animal breeders, the livestock industry, delivery businesses, any business with significant supply chains, particularly those that maintain inventory or handle fast moving consumer goods, and so on. These are all applications where a high priced tag is not practicable, particularly where the tag is disposable or is going to be sold with the product.
To address and overcome the li
Caputo Lisa M
Le Thien M.
RF Saw Components, Inc.
LandOfFree
Reader for a high information capacity SAW identification... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Reader for a high information capacity SAW identification..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Reader for a high information capacity SAW identification... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3260122