Multi-touch Resistive Touchscreen via Capacitor Charging Time

The patent divides the continuous sheet-shaped resistive layers into multiple separate resistive stripes in both the first and second transparent films. This segmentation enables the system to distinguish between multiple touch points by detecting which specific stripes are contacted, thereby achieving multi-touch recognition capability while managing structural complexity through systematic arrangement of the stripes.

The patent replaces the conventional voltage-reading method using ADC (analog-to-digital converter) with a capacitor charging time measurement method. Instead of measuring voltage levels that require complex ADC circuits, the system measures the time required for capacitors to charge through the resistive stripes, which can be implemented with simpler digital timing circuits that are more suitable for IC integration and consume less power while maintaining adequate measurement precision.

By segmenting the resistive layers into discrete stripes rather than using continuous sheets, the patent reduces measurement error inherent in sheet resistance variations. The striped configuration provides more defined current paths and reduces the impact of resistance variations across the surface, thereby improving touch position sensing accuracy without significantly complicating the manufacturing process, as the stripes can be formed using standard photolithography techniques.