Comparing the Different Touchscreen Technologies and How they Work

Touchscreen devices have become a regular part of our daily lives. From computers and tablets to smartphones, televisions and even commercial–grade human machine interfaces (HMI), they are practically everywhere you look. But while the fundamental principle behind these devices remains the same, they are powered by different technologies, some of which we’re going to discuss in today’s blog post.

Resistive

Among the most common type of touchscreen technology is resistive. Resistive touchscreen devices feature two layers that are separated by a third “inert” layer. When you press against the surface, it pushes the upper and bottom layers together; thus, it’s able to calculate the point of touch. Resistive touchscreens are often preferred because of their ability to be used with or without a stylus.

Capacitive

Another popular type of touchscreen technology is capacitive. These devices register touch by identifying the electrical charge produced by the operator. Pressing your finger against a capacitive touchscreen devices transmits a small but noticeable electrical charge to the device. This electrical charge isn’t enough to cause damage, but rather the device is able to identify it, using the information to determine the point of contact/touch.

Surface Wave Acoustic

Resistive and capacitive are the two most commonly used forms of touchscreen technology, but there are several others that shouldn’t be overlooked, including surface wave acoustic (SWA). In SWA, the device emits invisible ultrasonic waves over the display interface. Touching the surface of this interface causes a disturbance in the waves, allowing it to determine the point of touch. Although accurate, SAW touchscreens are not suitable for outdoor use. Furthermore, dirt, dust and other contaminants on the surface may interfere with its functionality.

Surface Capacitance

A fourth type of touchscreen technology is surface capacitance, which is unique in the sense that it only one side of the insulator contains a conductive layer. The device works by applying a small voltage to this layer, creating an electrostatic field that, when touched, allows the device to determine the point of contact. Surface capacitance devices have no moving parts, giving it greater durability than many other types of touchscreen devices. Drawbacks of surface capacitance, however, include greater susceptibility to false signals, as well as the need for calibration during the device’s manufacturing. Surface capacitance touchscreen devices are most commonly used in kiosks and industrial control panels.