Touchscreen devices receive their touch-based functionality from a specific type of touchscreen technology. In recent years, resistive and capacitive have become the top touchscreen technologies. You can find them in everything from smartphones and tablets to human machine interfaces (HMIs) and control systems. But there are many other, lesser known touchscreen technologies, including projected capacitance.
Projected Capacitance: The Basics
Projected capacitance is a variation of traditional capacitive touchscreen technology. It features a top layer of glass with conductive electrode film and a circuit chip. When turned on, the device creates an electrostatic field by running a uniform electrical current through the film. This is important because when a user touches the device’s interface, it disturbs the electrostatic field, thereby allowing the device to identify the point of contact.
After reading that, you might be wondering how projected capacitance differs from traditional capacitive touchscreen technology. Well, traditional capacitive touchscreen, also known as surface capacitance, doesn’t support multi-touch functionality. This is something that’s only available with projected capacitance — and it’s also the reason why Apple decided to use the technology in its iPhone.
Furthermore, projected capacitance is better at sensing touch commands. While surface capacitance devices only sense touch commands performed with a bare fingers, projected capacitance devices can sense touch commands with a bare finger or thin-gloved finger. Granted, projected capacitance devices don’t always work if you’re wearing thick gloves. Assuming the gloves are thin, such as Latex gloves, though, they should sense your touch commands. In comparison, surface capacitance devices only work with a bare finger.
How Projected Capacitance Was Created
According to Wikipedia, projected capacitance touchscreen technology was invented by Ronald and Malcolm Binstead in the mid-1980s. Back then, the brotherly duo created a basic touchpad featuring this technology. The touchpad contained an upper layer of glass that could sense variations in its electrostatic field. Touching the glass causes the user’s fiber to absorb some of the deivce’s electrical current.
About 10 years after the Binstead brothers’ invention, another company produced a project capacitance touchscreen device. In 1999, the term “projected capacitive” was coined for this technology, with it later being renamed to “projected capacitance.” Since then, projected capacitance has become an increasingly popular alternative to traditional capacitive and even resistive touchscreen technologies.
Projected capacitance is just one of many touchscreen technologies to consider. Whether you’re buying a single touchscreen device or 100, you should consider the pros and cons of each technology and whether it’s right for your needs.