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Resistive touch screen liquid crystal display (LCD)

LCDThe liquid crystal display (LCD) combined with a tactile membrane are two technologies that are increasingly used in different fields other than the automobile; the most obvious one is with the smartphone. LCDs do not emit light itself, but use the properties of light by modulating liquid crystals to create the image on the screen. But what is a liquid crystal? It is a state of matter which gives the optical characteristics of a liquid and that of a crystalline solid. These liquid crystals combined with a polarized screen horizontally and vertically by electric currents can form the image and manage each pixel.

As such, the LCD only displays an image, but by applying a thin tactile membrane, it becomes a versatile control tool. Techniques for detecting pressure on the membrane are the resistive, capacitive and inductive technologies. In our case, we opted for resistive membrane since its pressure detection performance are really good regardless of the medium used, must not forget that in vehicles, multiple users are wearing gloves. This approach is quite simple, as to detect the pressure point on the screen; we just have to check the resistivity of the membrane in the horizontal and vertical axis. It remains only to manage the image on the LCD according to this pressure.

Thanks to LCD touch screens, Zone Technologies can create user interfaces with almost infinite possibilities to control its products range. The user can therefore have an interface to its taste that meets their expectations.

Martin Lessard, eng.
Director of R&D department