They can be used effectively for simple panel controls, such as an automotive GPS panel control or other keypad-replacement applications, or in applications which require gloved use. Capacitive touch screens are commonly made of two layers a surface insulator and a transparent conductive layer beneath it.
Since the human body itself is an electrical conductor, when the touch panel is touched with a finger or a conductive pen , the electrostatic field of the panel is distorted.
This table breaks down some of the common advantages and disadvantages of resistive vs. PCAP only works with thin gloves or a finger. Appearance Reflections from an extra layer of material placed over the screen result in reduced contrast. Sliders or Rotary Knobs Possible, but not graceful. Cover Glass Not available. See sample with imprinted black border and logo. Resistive has to be touched. Can be improved with additional options which increase cost.
Scratch Resistance More easily scratched or damaged. Resistive touchscreens are meant to sense the location of one touch, and early generation touchscreens couldn't respond to two-finger pinch or zoom actions. However, later generations saw some mobile device manufacturers introducing new algorithms and other tricks that allowed for two-finger touch features.
In most cases such touchscreens are difficult or impossible to repair. Capacitive touchscreens were actually invented almost 10 years before the first resistive touchscreen.
Nevertheless, today's capacitive touchscreens are highly accurate and respond instantly when lightly touched by a human finger. So how does it work? As opposed to the resistive touchscreen, which relies on the mechanical pressure made by the finger or stylus, the capacitive touchscreen makes use of the fact that the human body is naturally conductive.
Capacitive screens are made of a transparent, conductive materialusually ITOcoated onto a glass material. It's the glass material that you touch with your finger. In a surface capacitive setup, there are four electrodes placed at each corner of the touchscreen, which maintain a level voltage over the entire conductive layer.
When your conductive finger comes in contact with any part of the screen, it initiates current flow between those electrodes and your finger. Sensors positioned under the screen sense the change in voltage, and the location of that change.
In a device that uses a projected capacitive setup, transparent electrodes are placed along the protective glass coating in a matrix formation.
One line of electrodes vertical maintain a constant level of current when the screen isn't in use. Another line horizontal are triggered when your finger touches the screen and initiates current flow in that area of the screen.
The matrix formation creates an electrostatic field where the two lines intersect. This is one of the most sensitive types of touchscreens, and is how some phones can sense a finger touch even before you make contact with the screen itself. Projected capacitive technology also allows you to use the touchscreen even when you're wearing thin gloves. The choice to use a capacitive or resistive touchscreen depends largely on the application for the device. Most devices with resistive screens are used in manufacturing, ATMs and kiosks, and medical devices.
This is because in most industries the users need to wear gloves when using the touchscreens. Capacitive screens are typically used in most consumer products like tablets, laptops, and smartphones.
If it weren't for cutting edge touchscreen technologies, we could never enjoy cool new applications like Opera's one-handed browsing for Android.
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