Hybrid Time/Frequency Domain Electromagnetic Encoders Dispenser-Printed on PET Substrate

In this paper, hybrid time/frequency domain electromagnetic encoders implemented on polyethylene terephthalate (PET) substrate by means of direct-write dispenser-printing, using conductive inks, are presented for the first time. The encoders are based on chains of linear strips (inclusions) transversally oriented with regard to the chain axis, and frequency encoding is achieved through the size of the inclusions. Specifically, four different sizes are considered, corresponding to two bits of information per chain period. The determination of the specific 2-bit ID code for each chain period is carried out sequentially, in a time-division multiplexing scheme, by means of a dedicated reader, able to detect the size of the inclusions. The functionality of the new dispenser-printed encoders (and reader) is experimentally demonstrated by considering two different systems. In one system, the encoders are based on a single chain of inclusions, whereas the reader is a simple gap-loaded line fed by four harmonic signals. In the other system, the encoder is made of two chains of inclusions, whereas the reader is based on a power splitter, also fed by four harmonic signals. The main relevant contribution of this paper concerns the fact that it is demonstrated that enhancing the bit density in electromagnetic encoders is compatible with encoder implementation on PET substrate through dispenser-printing process.