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A full integration of electromagnetic resonance sensor and capacitive touch sensor into LCD
Author(s) -
Uchino Satoshi,
Azumi Kohei,
Katsuta Tadayoshi,
Suzuki Daich,
Ozawa Yutaka,
Sakai Toshirou,
Mitsuzawa Yutaka
Publication year - 2019
Publication title -
journal of the society for information display
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.578
H-Index - 52
eISSN - 1938-3657
pISSN - 1071-0922
DOI - 10.1002/jsid.777
Subject(s) - capacitive sensing , materials science , electromagnetic coil , liquid crystal display , signal (programming language) , computer science , noise (video) , controller (irrigation) , optoelectronics , acoustics , electrical engineering , artificial intelligence , engineering , agronomy , physics , image (mathematics) , biology , programming language , operating system
Abstract We have developed a transmissive and reflective LCD that integrates electromagnetic resonance (EMR) and capacitive touch sensors using existing in‐cell process. This development has been achieved by utilizing our hybrid‐in‐cell technology with low resistance material for the RX, which is an improvement of over 80% compared with conventional indium thin oxide (ITO) material. For EMR detection, we have slightly modified the TX layer used for capacitive touch sensing, by making a coil loop that generates a magnetic field on the panel. The direction of current on the coil can be modulated by the low‐temperature polycrystalline silicon (LTPS) circuit. Our in‐cell touch sensing has separately assigned timings for display and touch units. This time‐sharing method provides immunity from display noise and consequently better signal‐to‐noise ratio (SNR) than other out‐cell types. In parallel, we have developed a new controller that can support both EMR and capacitive sensing as a one‐chip solution, with the capability of maximizing signal levels lowering noise and detecting the frequency precisely when there is pressure on the pen tip. Our in‐cell technologies contribute not only a good SNR for EMR pen but also the added benefits for thin design, lightweight panel, compared with conventional LCD techniques.