Electromagnetic induction is closer to the man-machine interface (MMI) of the digitizer than the touch screen in the general sense. It is a method that uses the electromagnetic induction of several sensor coils covering the side panel and a special pen. Although it is rarely applicable in Japan, its scope of application has been extended to tablet computers in Europe and the United States. The battery-free "EMR (Electro Magnetic Resonance) mode of action" that does not require batteries in the pen has become the mainstream. This is not only the output of electromagnetic waves from the pen, but the pen and the induction coil to detect its position by receiving electromagnetic energy. . The following is a description of how EMR works.
① Pass a short-term current to the induction coil group of the panel to generate an electromagnetic field on the induction surface.
② When the pen is close to the sensor, the coil inside the pen will induce current to charge the pen's capacitor.
③ When the pen capacitor discharges, the coil on the side of the pen generates a magnetic field.
④ The induction coil is designed as a sensing mode, and the inductor near the pen will generate an induced current.
⑤ Calculate the coordinate position from the output distribution of the induction coil that generates the induced current. Since the EMR mode of action can accept electromagnetic energy, the liquid crystal display devices that can be used are limited. The low{{0}}temperature polysilicon (LTPS) thin-film liquid crystal display. The TAB 1C for driving is set around the panel. It has a structure similar to a kangaroo pocket, and the sensor unit is easy to install. The accuracy is about ±0.5 on 15in products. In addition, the pen has an eraser function, and the pen pressure resolution can reach 8bit. It can be said that in the current touch screen, there is no better than this to recognize the signal.
