Touch panels have become key components for display devices today. As we see in the market, touch panels, especially projective capacitive (PCAP) touch panels, are used for most handheld devices such as smart phones. Most of these touch panels offer various gesture inputs and multi-touch functions to enable intuitive touch operation. As nowadays the demand for gesture input and multi-touch function is also increasing in the industrial market, Mitsubishi Electric has developed the PCAP technology meeting industrial specifications such as extended temperature range, excellent color quality and wide viewing angles. TFT-LCDs are used in a wide range of applications that require reading from various viewing angles, positions and ambient conditions. Historically resistive type touch panels have been much more widespread in the market, and their base glass and film (or thin glass) structure has been used in most of cases until now. Industrial applications, though, require more durable and reliable touch panels like PCAP. Their features such as high durability, resistance to water or chemical liquid, multi-touch functionality, gesture input etc. are ideally suited for the rough environment of the industry.
LCD with PCAP touch panel
The touch panel unit consists of two sheets of glasses, the cover glass and the sensor glass. These are bonded together to form the touch panel unit. This unit is then bonded or attached with double sided adhesive tape to the LCD module. Also the touch panel controller PWB is implemented on the back side of the LCD module metal frame with screws and covered with another metal plate to secure grounding. The touch controller PWB and the user�??s system are connected via USB or UART I/F. Moreover touch panel driver software for Windows 7 and Linux is supported. Mitsubishi Electric provides total support to customers including LCD module, touch panel, touch panel controller and software.
Technical advantages of PCAP touch
Mitsubishi Electric‘s original controller firmware and sensing method enables touch sensing through 2.8 mm thick cover glass even using gloves, as compared to the cover glass of consumer products with a thickness of about 1 mm. In addition Mitsubishi Electric realized PCAP touch panels with optical bonding. Generally optical bonding resin has a dielectric constant value three times higher as compared to air. This means noise from LCDs affects touch panel sensing much more. Furthermore, Mitsubishi Electric PCAP works with in-plane switching mode LCDs which have a relatively higher noise level compared to TN mode LCDs. Although the combination of these technologies generally deteriorates PCAP sensing ability, Mitsubishi Electric realized the combination with accurate sensing by its proprietary original controller firmware and sensing method. Mitsubishi Electric PCAP touch panels also offer gesture input like pinch-in, pinch-out and flick with multi-touch function. This enables intuitive operation for industrial applications, too. Thin metal signal lines as sensing electrode are produced by in an in-house TFT array process, instead of transparent metal like ITO. This insures clear images and less color shift from the original LCD module. Signal line shape is considered, too, to avoid outside light reflection. And with optical bonding technology and AR surface treatment glass it is possible to obtain a better image quality and lower surface reflection for outdoor use. It is also feasible to use designed glass like black mask printing. Because sensor glass and protection glass are separated, it is technically easier to use a designed protection glass.
Rugged design for various applications
Mitsubishi Electric PCAP does not malfunction when water drops are on the surface. The company offers thick 2.8mm glass with a high resistivity to scratches and break. This thick glass is ideal for use in different locations and conditions, such as in ATM, POS and kiosks placed at public places, as well as in marine, automotive and other outdoor applications.
PCAP-integrated LCD as reliable solution
Generally PCAP is more sensitive to electrical noise. Especially if in-plane switching or VA type LCDs or if larger size LCDs are used, if LCD and touch are optically bonded or thicker protection glass is utilized, electricity has a greater influence on the PCAP touch panel. And when customers purchase these parts separately, they have to evaluate, adjust or evaluate matching of the combination. Mitsubishi Electric PCAP touch panels can solve the above-mentioned issue and can offer reliable solutions, because touch panel and LCD are already bonded (or attached with double sided adhesive tape) to form one complete solution with confirmed matching of all components and adjusted controller .Another advantage is the warranty and support of the complete unit from Mitsubishi Electric. Mitsubishi Electric believes the PCAP technology is essential for industrial applications in the near future. Therefore the company will develop various sizes of PCAP matching its TFT-LCD modules.
