4-Wire Resistive touch technology consists of a glass or acrylic panel, coated with electrically condictive &  resistive layers.  Layers are separated by “invisible” separator dots. When operating, an electrical current moves through the screen. When pressure is applied to the screen the layers are pressed together, causing a change in the electrical current & a touch event to be registered.

Resistive Touchscreens Advantages

• Pressure sensitive, works with any stylus
• High touch resolution
• Affordable touchscreen technology
• Not affected by dirt, dust, water, or light

Resistive Touchscreens Disadvantages

• Resistive layers can be damaged by a sharp object
• Less durable then 5-Wire Resistive Touchscreen technology
• 75 % clarity

4 Wire Touchscreens Specifications:

• Speed of Response (in milliseconds) – 10 ms maximum
• Accuracy – 3 mm maximum error
• Light Transmission – 75-85 %
• Touch Resolution – 1024 x 1024
• Lifespan > 5 million touches

The distance along the x-axis at the point of touch is measured by creating a horizontal voltage gradient on the top sheet, with the bottom acting as the return layer. Next, a vertical voltage gradient is created on the bottom layer, to measure the y-axis.

(resources: touchscreenguide.com, touchscreens.com)