How Do Touchscreens Work?

A complete overview of the most modern touch screen technologies

Have you ever wondered how touchscreens work? A few years ago touchscreens were futuristic and only used in industrial applications. Today we don't even think twice before tapping or swiping a touchscreen around us. 

How a Touchscreen Works and Why They Crave (Skin) Contact

First of all, it's good to know there is not one way a touchscreen works. Each technology operates differently. This means the touchscreen in your local ATM and the one in your iPhone are completely different. All touch technologies mentioned below can still be purchased. However, resistive and projected capacitive touchscreens are used most in todays' applications.

Resistive Touch Screens

How Resistive Touch Works
Screens you tap at the ATM, supermarket check outs or kiosks are usually fitted with a resistive touchscreen. The resistive touch technology is the most widely used touch technology today. A resistive touchscreen consists of two thin flexible metallic layers with a gap in between. These two layers have an electric current running through them. When touched the top flexible layer touches the bottom one, interrupting the electrical current. The device notices this and detects the point of contact by the change in electrical flow. Of course this all happens at warp speed.

Advantages

• Use pretty much any object to touch - finger, stylus, pen, gloved hand, etc.
• Solid feel
• Lowest cost
• Low power consumption
• Resistant to surface contaminants and liquids - dust, oil, grease, water, etc.

Disadvantages

• Image clarity not as great as other technologies
• Outer touch layer is vulnerable to damage - scratching, poking with sharp objects, etc.

Capacitive Touch Screens

How Capacitive Touch Works
For a long time capacitive touch was the second most popular touch technology out there. A capacitive touchscreen uses a transparent electrode layer. This layer is placed on top of a glass panel and covered by a protective layer. When a finger touches the touchscreen, some of the electrical charge transfers from the screen to the user. Sensors in all four corners of the screen detect the decrease of electric current. The controller than determines the touch point. CAPACITIVE TOUCH SCREEN can only be activated when touched by human skin or a stylus holding an electrical charge. Despite its long term popularity, capacitive touch now gets replaced by projected capacitive touchscreens.

Advantages

• Great image clarity (better than resistive touch)
• Durable screen
• Excellent resistance to surface contaminants and liquids - dust, grease and water
• High scratch resistance

Disadvantages

• Only works with bare finger or special capacitive stylus
• Sensitive to EMI (Electromagnetic Interference) and RFI (Radio Frequency Interference)

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