The PN-L802B/L702B/L602B's integration of a high-quality LCD panel and a highly sensitive touchscreen makes for easy communication. For heightened touchscreen responsiveness and stress-free onscreen writing, the PN-L702B and the PN-L602B employ Sharp's proprietary infrared blocking detection system, which uses multiple infrared sensors to locate the position of the user's finger or the touch pen. The PN-L802B employs a system better suited for very large screens: optical imaging technology uses optical cameras in the upper right and left corners of the screen to detect shadows made on the screen by the user's finger or the touch pen.