A full integration of electromagnetic resonance sensor and capacitive touch sensor into LCD

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 lowtemperature polycrystalline silicon (LTPS) circuit. Our in-cell touch sensing has separately assigned timings for display and touch units. This timesharing 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.

P‐126: Surveys on the Stylus Technologies for Capacitive‐Type Touch Systems

“…For various expressions such as the pressure and tilt angle, the EMR-type passive stylus has been adopted for mobile devices (6)(7). Figure 3 shows the conceptual diagram of the EMR-type passive stylus and its sensing system.…”

“…Among the several types of passive styli, the capacitive type (C-type) is dominantly used with the CTS because of its small thickness and weight, and the low fabrication cost, but it can express the only coordinate of stylus with a low sensitivity. The electromagnetic resonance (EMR) type (3,(6)(7) stylus can express the pressure and tilt angle with a high resolution and sensitivity, but it requires an additional EMR sensor under the display panel, which increases the power consumption, fabrication cost, weight, and thickness of the CTS. The electrically coupled resonance (ECR) type stylus can express the pressure without an additional sensor, but it can represent only a pressure expression with a low resolution (8)(9).…”

Active stylus‐touch discrimination scheme based on anomaly detection algorithm

“…[1][2][3][4][5] In addition, more elaborate input tools have been demanded for writing texts and drawing pictures. Consequently, various types of input tools such as passive, 6 active, [7][8][9] and electromagnetic resonance 10,11 stylus pens have been developed. A passive stylus is a simple technology that mimics a finger by using conductive fibers on existing touch screen panels (TSPs).…”

Sensor applications of thin‐film devices originating in display technologies

“…Moreover, it is required to equip sensor devices in FPDs to realize interactive displays . Conventionally, touch panels are equipped outside the FPDs . However, if the sensor devices can be made by thin‐film devices that have been already utilized for FPDs, they can be made without additional cost.…”

“…5,6 Conventionally, touch panels are equipped outside the FPDs. [7][8][9][10][11][12][13] However, if the sensor devices can be made by thin-film devices that have been already utilized for FPDs, they can be made without additional cost. Therefore, thin-film devices are again promising for sensor applications especially for interactive displays.…”