CN-115688848-B - Surface acoustic wave label structure adopting one mask plate and coding identification method thereof

CN115688848BCN 115688848 BCN115688848 BCN 115688848BCN-115688848-B

Abstract

The invention discloses a surface acoustic wave label structure adopting a mask plate and a coding identification method thereof, all the coded labels are manufactured by adopting the same mask plate, and the labels are coded by the difference of external capacitors. The surface acoustic wave tag includes a plurality of reflector grating pairs, each reflector grating pair being formed of a reference reflector grating and a load reflector grating circumscribing a load capacitor, and the capacitance of the load capacitor having a plurality of selectable values corresponding to a code that may occur for each reflector grating pair. In view of the fact that the reflectivity of the load reflecting grating changes along with the change of the external capacitor, the encoding value of the reflecting grating pair is obtained through the amplitude ratio of two echo pulse signals corresponding to the load reflecting grating and the reference reflecting grating, and finally the encoding of the surface acoustic wave tag is identified. The invention is characterized in that only one mask is needed, and the coding capacity can be dynamically expanded, and the identification method not only eliminates the influence of distance, but also avoids the coupling influence of codes between different reflection grid pairs.

Inventors

LIU XIANGYU
CHEN ZHIJUN
CHEN ZHI
ZHU WEIJUN
XU HAILIN
XIA QIANLIANG

Assignees

南京航空航天大学
中电科技德清华莹电子有限公司

Dates

Publication Date: 20260505
Application Date: 20221104

Claims (3)

1. A surface acoustic wave label structure adopting one mask is characterized in that all the coded surface acoustic wave labels are manufactured by adopting the same mask, and the codes of the surface acoustic wave labels are determined through the difference of external capacitors; The surface acoustic wave tag structure comprises a piezoelectric substrate, an interdigital transducer, m reflecting grating pairs, m load capacitors and an antenna, wherein the interdigital transducer is deposited on the left side of the surface of the piezoelectric substrate, the 1 st reflecting grating pair, the 2 nd reflecting grating pair, the m th reflecting grating pair are deposited in the right subsequent space of the surface of the piezoelectric substrate in the sequence from near to far according to the distance between the interdigital transducer, each reflecting grating pair consists of a reference reflecting grating and a load reflecting grating, the reference reflecting grating adopts an open-circuit grating structure, the load reflecting grating adopts an interdigital grating structure, the number of the load capacitors is equal to that of the reflecting grating pairs, and each load reflecting grating is externally connected with one load capacitor; The capacitance value of each load capacitor has n selectable options, corresponding to n codes possibly appearing in each reflecting grating pair, which are marked as1, 2, and n, the codes of the 1 st reflecting grating pair, the 2 nd reflecting grating pair, and the m th reflecting grating pair are respectively marked as x 1 、x 2 、…、x m , the codes of the surface acoustic wave labels are correspondingly marked as x 1 -x 2 -…-x m , and the coding capacity of the surface acoustic wave labels comprising m reflecting grating pairs is n m .
2. The surface acoustic wave tag structure adopting one mask plate according to claim 1 is characterized in that the antenna is manufactured on a PCB, the m load capacitors are welded on the PCB on which the antenna is manufactured, the piezoelectric substrate, the interdigital transducer and the m reflecting grids are packaged after the manufacturing of the mask plate is completed and then welded on the PCB on which the antenna is manufactured, bus bars at two ends of the interdigital transducer are connected with the antenna on the PCB through bonding pads on the packaging, and bus bars at two ends of each load reflecting grid are connected with one capacitor on the PCB through bonding pads on the packaging, so that the surface acoustic wave tag is integrated on the PCB.
3. The coding identification method of the surface acoustic wave tag structure adopting one mask as claimed in claim 1 or 2, wherein the method comprises the following steps: step A, aiming at the acoustic surface wave labels with different codes, welding load capacitors with corresponding capacitance values at corresponding positions on a PCB, and attaching the PCB to an object to be identified; the reader transmits an excitation pulse signal, the excitation pulse signal enters an interdigital transducer after being received by an antenna of the surface acoustic wave tag, the excitation pulse signal is converted into a surface acoustic wave through an inverse piezoelectric effect, and the surface acoustic wave is propagated to m reflection grid pairs along the surface of the piezoelectric substrate; Step C, the acoustic surface wave generates partial reflection and partial transmission through a1 st reference reflecting grating of the 1 st reflecting grating pair, and the transmission signal generates partial reflection and partial transmission through a1 st load reflecting grating of the 1 st reflecting grating pair, wherein the two acoustic surface wave reflection signals corresponding to the 1 st reference reflecting grating and the 1 st load reflecting grating are transmitted back to the interdigital transducer, and the two acoustic surface wave reflection signals are converted into two echo pulse signals through a positive piezoelectric effect and are recorded as e 11 、e 12 ; Step D, continuously transmitting the surface acoustic wave transmission signal generated by the 1 st load reflecting grating along the surface of the piezoelectric substrate, wherein the reflection and transmission processes of the signal generated by the 2 nd reflecting grating are the same as those of the step C, and two echo pulse signals corresponding to the 2 nd reference reflecting grating and the 2 nd load reflecting grating are marked as e 21 、e 22 ; The reflection and transmission processes of the signals generated by the surface acoustic wave passing through the 3 rd reflecting grating pair, the m-th reflecting grating pair are the same as those of the step C, and the two echo pulse signals corresponding to the 3 rd reference reflecting grating and the 3 rd load reflecting grating are marked as E 31 、e 32 , and the two echo pulse signals corresponding to the m-th reference reflecting grating and the m-th load reflecting grating are marked as E m1 、e m2 ; And F, transmitting 2m echo pulse signals corresponding to the m reflecting grating pairs back to the reader through the antenna to form echoes of the surface acoustic wave tag, processing the two echo pulse signals of the 1 st reflecting grating pair to obtain the amplitude ratio of the 1 st load reflecting grating to the two pulse signals e 12 、e 11 corresponding to the 1 st reference reflecting grating, and recording as p 1 , wherein the code x 1 of the 1 st reflecting grating pair is obtained according to p 1 due to the corresponding relation between the reflectivity of the load reflecting grating and the externally connected load capacitance, and the code x 2 、…、x m of the 2 nd reflecting grating pair is obtained by adopting the same signal processing and analyzing method, so that the code x 1 -x 2 -…-x m of the surface acoustic wave tag is identified.

Description

Surface acoustic wave label structure adopting one mask plate and coding identification method thereof Technical field: The invention relates to a surface acoustic wave tag structure and a coding identification method thereof, belonging to the field of radio frequency identification. The background technology is as follows: In recent years, the technology of the internet of things is rapidly developed, and network connection requirements among people, objects and objects are met in various industries. An accurate, efficient and low-cost radio frequency identification system is an essential basis of the Internet of things, and a tag and a reader are indispensable components of the radio frequency identification system. The surface acoustic wave tag is a novel coded tag, takes a piezoelectric material as a substrate, utilizes the piezoelectric effect, excites the surface acoustic wave on the substrate through an interdigital transducer, and mainly realizes the identification of codes according to the characteristic that the echo characteristics of the tag change along with the coding of the tag. Under the cooperation of the reader and the antenna, the surface acoustic wave tag does not need a power supply in the working process, has the advantage of passive and wireless, and is small in size and easy to integrate. Compared with an IC tag, the surface acoustic wave tag has better anti-interference capability in complex environments such as electromagnetic interference and the like. The existing surface acoustic wave tag generally adopts coding schemes such as pulse amplitude, pulse delay combined with phase and the like, and has the following problems: (1) The method has the advantages that the coding capacity of a pulse amplitude scheme is extremely small, the number of reflection grids of different coded labels is different, the consistency design of label echoes is difficult to realize, the subsequent reader design and identification algorithm are difficult to realize, the coding capacity is still limited although the number of reflection grids of all labels of the pulse delay scheme is the same, the coding capacity of the pulse delay scheme is improved to a certain extent, compared with the pulse amplitude and the pulse delay, the coding capacity of the pulse delay combined with the phase scheme is greatly improved, but the phase coding is obviously influenced by temperature, therefore, the temperature is required to be corrected in a targeted way during identification, and the phase itself has 360-degree ambiguity problem, so that the label design and identification algorithm are complex. (2) To achieve different pulse amplitudes, delays or phases of tag echoes, the structures of the different tags are not identical, although similar. The surface acoustic wave tag is usually manufactured by adopting a photoetching process, and aiming at the surface acoustic wave tags with different codes, the three existing schemes are all required to adopt different masks, which is extremely expensive in cost. Therefore, for cost reasons, besides the small-capacity coding, the large-scale application scene of the internet of things with the large-capacity coding is hardly realized, and the large-scale application scene is just the bottleneck faced by the surface acoustic wave radio frequency identification technology at present. (3) In the processing and manufacturing process of the surface acoustic wave tag, the mask version body with high cost has the characteristic of reusability, so that the overall cost of the surface acoustic wave radio frequency identification system can be reduced to be put into practical application. However, each mask plate of the existing three coding schemes has a one-to-one correspondence with each code, and the characteristic that the mask plate can be reused cannot be fully exerted. (4) The coding capacity of the surface acoustic wave tag in the existing three schemes is determined by design rules, and once the design and manufacturing work is completed, the coding capacity cannot be changed. When the coding capacity is insufficient due to the upgrading of the application scene, the design rule is generally required to be changed and labels are manufactured again, and all the original labels cannot be used, so that the dynamic expansion of the coding capacity cannot be realized. The invention comprises the following steps: aiming at the problems of the existing surface acoustic wave tag coding scheme, the invention provides a surface acoustic wave tag structure adopting a mask plate and a coding identification method thereof, which can break through the bottleneck of the surface acoustic wave radio frequency identification technology to a certain extent and have the open expansion function of coding capacity. The invention adopts the following technical scheme that a surface acoustic wave label structure of one mask plate is adopted, all the coded surface acoustic wave labels are manufactu