Method of manufacturing piezoelectric wafers of saw identification tags

Abstract

The invention provides a method of manufacturing piezoelectric wafers of surface acoustic wave (SAW) identification tags. In one embodiment, the method includes: (1) using a master reticle to form, on each of the piezoelectric wafers, wafer-independent patterns that encode digits of a first significance for SAW identification tags; and (2) using different ones of a library of coding reticles to form, on each of the piezoelectric wafers, wafer-dependent patterns that encode digits of a second significance for SAW identification tags.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application is a Divisional of prior application Ser. No. 10 / 059,700 filed on Jan. 28, 2002, currently pending to Clinton S. Hartman et al. The above-listed Application is commonly assigned with the present invention and is incorporated herein by reference as if reproduced herein in its entirety under Rule 1.53(b).TECHNICAL FIELD OF THE INVENTION [0002] The present invention is directed, in general, to a method of manufacturing identification tags and, more specifically, to a method of manufacturing a surface acoustic wave (SAW) identification tag having enhanced data content. BACKGROUND OF THE INVENTION [0003] A fascinating and increasingly important technology is that dealing with object identification systems. Such systems range from simple bar codes to very sophisticated systems still in the process of development and implementation. Among the most promising object identification systems are those using electronic tags attached ...

AI Technical Summary

Benefits of technology

"The present invention provides a method of manufacturing piezoelectric wafers of SAW identification tags with increased data capacity. The method involves using a master reticle and different coding reticles to form wafer-independent and wafer-dependent patterns that encode digits of a first significance for SAW identification tags. This allows tags to contain a globally unique number, which can be used for identifying and tracking an unprecedented number of objects uniquely and reliably. The method also includes using a programmable stepper or a one power reticle to form the wafer-independent and wafer-dependent patterns. Other features of the invention include forming reflectors that encode the digits of a first and second significance, and using framing and end reflectors to frame a return signal. These features allow for more data to be encoded on each SAW identification tag and improve the reliability and accuracy of the tagging process."

Problems solved by technology

The difference in cost and performance between the two types is so radical that the two categories rarely compete with one another for a particular type of use.

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.

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 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.

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.

A huge gap exists in the automatic identification market between the very low cost bar codes and the higher performing RFID chip tags.

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