It’s a common assumption that all touchscreen devices support styluses for input. While there are plenty of smartphones, tablets and human machine interfaces (HMIs) that support styluses, some only work with a bare finger. If you attempt to use one of these devices with either a gloved finger or stylus, it will fail to register your touch command. So, why do some touchscreens only work with a bare finger?
Capacitive Touchscreens Only Work With a Finger
The reason some touchscreens only work with a bare finger is because they are powered by capacitive touch-sensing technology. If you follow our blog here at Nelson-Miller, you’re probably aware that there are two primary types of touchscreen technology: resistive and capacitive. The former relies on pressure on detect touch commands, whereas the latter relies on capacitance fluctuations to detect touch commands.
With capacitive touchscreens, a uniform electrostatic charge is produced through the top layer. When you touch the display with a bare finger, your body will absorb some of this charge. It’s not enough to cause a noticeable shock, but it’s still enough for the device to detect as a change in capacitance, which it uses to determine where exactly you touched. Attempting to control a capacitive touchscreen with a gloved finger or stylus won’t work because gloves and styluses aren’t conductive.
What About Projected Capacitive Touchscreens
Most capacitive touchscreens use surface capacitive technology to detect touch commands. In recent years, however, projected capacitive has become an increasingly popular solution.
Projected capacitive touchscreens also detect touch commands by looking for a change in capacitance. They feature more accurate sensing than their surface capacitive counterpart, allowing them to detect touch commands through thin gloves or while using a stylus.
Why Capacitive Touchscreens Are Preferred Over Resistive
Being that resistive touchscreens support a gloved finger and stylus — as well as bare-finger touches — you might be wondering why so many device manufacturers prefer capacitive technology. For starters, capacitive touchscreens offer a higher-quality display with a greater degree of contrast.
Second, capacitive touchscreens can easily detect the precise location of your touch commands. Your finger will absorb some of the device’s electrostatic charge from the area where you touch it. Capacitive touchscreens, whether surface capacitive or projected capacitive, will detect the exact location of your touch commands by measuring capacitance.
Third, capacitive touchscreens tend to last longer than resistive touchscreens. Resistive touchscreens contain multiple layers that press together when touched. Over time, the constant pressing of these layers can cause them to fail sooner than a traditional capacitive touchscreen.
