Not all touchscreen devices are powered by capacitive or resistive touch-sensing technology. In recent years, resistive and capacitive have become the most popular types of touchscreen technology. From smartphones and tablet computers to cameras, infotainment centers and human machine interfaces (HMI), they are used in a wide variety of touchscreen devices. But there are many other types of touchscreen technology, including projected capacitance. While projected capacitance lacks the popularity of resistive and capacitive, it’s still a viable alternative for manufacturers to consider. To learn more about projected capacitance touchscreen technology and the history behind this touch-sensing technology, keep reading.
What Is Projected Capacitance?
Projected capacitance is a type of touch-sensing technology that works in a similar manner as capacitive touch-sensing technology. The device creates an electrostatic field across the interface. And upon this interface, the user absorbs some of the electrostatic field through his or her finger, thereby allowing the device to determine the point of contact.
There are several different ways to create a projected capacitance device, though the most common involves the use of a grid-like array of conductive material that’s embedded on one or more sheets of glass.
Origins and History of Projected Capacitance
Some people assume that projected capacitance is a new form of touch-sensing technology, but this isn’t necessarily true. It’s actually been around for several decades, with some of the earliest examples dating back to the mid-1980s. According to Wikipedia, brothers Ronald and Malcolm Binstead developed projected capacitance technology in 1984. The brotherly duo were able to create a projected capacitance touchpad featuring 16 individual keys. Pressing any of these keys caused the user to absorb some of the keypad’s electrostatic charge — much like a traditional capacitive touchscreen device.
The Binstead brothers were able to create a highly accurate and responsive projected capacitance device by updating the idle, “no touch” position for each key and reducing problems associated with dirt and debris. Furthermore, they designed their projected capacitance keypad so that the value of each key was relative to the value of the other keys.
A defining feature that distinguishes projected capacitance touchscreen devices from traditional capacitive touchscreen devices is that the former can identify touches from a gloved finger or stylus. This is a huge benefit that allows for greater versatility. While traditional capacitive touchscreen devices only identify touches from a bare finger, projected capacitance devices support touch commands from a bare finger, gloved finger or even a stylus.