Have you ever wondered why some touchscreen devices are operated by hand, while some others are operated by hand, and they can’t be operated in any other way? If you’ve been using PDA in its early days, having stylus is a must, and losing one is a disaster. Without the stylus, though you can operate the PDA by pressing your finger against it, the PDA’s response is usually cumbersome. On the other hand, if you use a newer touchscreen devices like iPhone and iPad, you will discover the opposite reaction from the device: it doesn’t react to either stylus or pointed tools. How come?
The reason is that, currently there are two different kinds of touchscreen available on the market; resistive, and capacitive, and they are working on different principles.
Resistive – creating touch point
Resistive touchscreens work by separating two thin layers of sensors with a gap, so that when user presses the layer surface with a stylus, it will bend and touches the other layer, creating a touch point. This touch point then, is regarded by the device as the user’s selection. We can still uses resistive touchscreen with bare finger pressing, however the response usually is cumbersome. This is due because technically, it excels at detecting pointed touch points, but not a larger touch area which created when a finger instead of a stylus presses the surface.
Capacitive – creating touch area
Capacitive touchscreens works in quite a different way; instead of relying on user to force the touching of two separate layers of sensors, it works by sensing a conductivity — the electricity transferring feature that naturally occurs in water-consisted things, like our human fingers. This is why using a regular stylus on capacitive screen won’t work, since usually the stylus is made from plastic which doesn’t have a conductive feature.
Which one is better?
At the moment the capacitive technology is newer and many considers as better than resistive, due to its ease of operation by using only your own finger and the considerably fast response. The newer capacitive touchscreens are even better with the ability to sense multiple touch areas, which enables the cool feature like pinch and spread to zoom in and zoom out, and the rotate function. However capacitive touchscreens have bad accuracy hence is not preferred for precision works.
The resistive touchscreens on the other hand, is capable to detect a pin sized touch point hence are better for tasks which requires precision.
Addressing and Aligning User Behaviour
As a User Experience Designer, knowing the difference between resistive and capacitive touchscreens could make a great difference. With capacitive screens that detects touch areas, and users are using it with their fingers, we must be careful not to design action areas in our design with size too small to be touch by human fingers. We don’t want them to put extra efforts in aiming their finger to press an area on the screen, because we want to make it as painless as possible to support a good, positive User Experience.
On the other hand, if you are designing the User Interface on devices with resistive touchscreen, you can create a finer and tight spacing action areas, which sometimes are still needed on mapping, or drawing applications. Or a target shooting game.
In addition, you could also address in the user manual that when the touchscreen is not as responsive as it should, then for resistive touchscreen the user need to press a bit harder, while on the capacitive touchscreen the user need to press a little longer without applying extra force, as the goal is to helps the screen easier to detects the conductivity from your finger.
Beside of the two, there are other touchscreens technologies available on the market today, as outlined in this article on Wikipedia. However the two mentioned here are the most used by today’s touchscreen personal devices. (byms)