Resistive Sensor Technology

Found in many small devices and consumer electronics, Resistive sensor technology is perhaps the most common technology in evidence today. Found in familiar places like the credit card machine at the local market to PDA's, resistive touch sensors are constructed in 4, 5, 7 and 8-wire versions, with the additional wires added to enhance touch sensitivity and reduce drift.

Function is provided by assembling a polymer film layer and two layers of ITO conductive coating separated by spacers along with a glass or acrylic back surface. A voltage gradient applied to both top and bottom conductive surfaces creates an X-Y field. Applying a touch force to the surface closes the contact between the top and bottom layers, creating a "switch" from which the touch controller reads positioning.

A key positive advantage to resistive sensor technology is that it responds well to a variety of inputs, whether bare finger, gloved hand or stylus.

Resistive is a flexing mechanical touch system and therefore introduces wear-out potential. The conductive coating itself is diminished with each use and is highly susceptible to scratches and other abuses.

Opitcal clarity is less than other technologies, usually performing at about 75-80% light transmission. Time, heat and humidity can be this technology's enemy, resulting in layers separating, creating a "pillowing" effect and further reducing optical clarity and overall performance.

 

Resistive: Key Points

• wide variety of inputs including finger, gloved hand or stylus touch
• lower initial cost
• highly susceptible to scratches or surface damage
• surface conductive coating wears with each use
• several points of potential wear-out mechanisms
• lowest optical clarity among technologies