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Touch screen vs touchpad: compring input device technologies

An overview of the differences between these two common input devices

Touch screens and touchpads are two of the most common control systems for laptops. They allow users to guide to select icons without a traditional mouse. Users can move their finger across the touch screen or touchpad while tapping icons of the programs or files they want to open. Touch screens and touchpads aren't the same, however. While they both provide a means of input for laptops-as well as other devices-they work in different ways. What's the difference between a touch screen and a touchpad exactly?

Human computer interface

What is a touch screen?

A touch screen is a multilayered interface panel that allows users to control a device through touch. They are typically used in conjunction with a display device, such as a liquid-crystal display (LCD). The display device creates visual images, which the user can touch to control it.

Human computer interface

According to the Institute of Physics (IOP), touch screens work using electricity:

The screen is made of glass, an insulating material that can't carry an electric current. The surface of the screen is therefore coated with a thin layer of an electrically conducting material such as indium tin oxide. The conducting layer is connected to a low voltage so that for a short time, there is a tiny electric current on the screen. This leaves it with a small electric charge.

When your finger touches the screen, some of the small electrical charge flows onto it. Don't worry - the voltages and amounts of electric charge are far too small to give you a shock.

Touch screens have been around for decades. Over the years, though, they've become more and more popular. Businesses and consumers often prefer them over traditional non-touch screen devices. Touch screens offer an easy and satisfying way to control devices, including laptops, tablets, human machine interfaces (HMI), infotainment systems, and more.

Some of the most common types of touch screen technologies include the following:

  • Surface capacitance
  • Projected capacitance
  • Three-wire resistive
  • Four-wire resistive
  • Five-wire resistive
  • Surface acoustic wave (SAW)
  • Infrared (IR)

What is a touchpad?

A touchpad, on the other hand, is an input device that uses a tactile sensor to convert finger motions into commands. Touchpads are found on most laptops. They eliminate the need for a mouse by providing a similar method of control for the cursor. Rather than using a mouse, users can glide a finger across the laptop's touchpad to move the cursor.

Human computer interface

Resistive touchpads operate using the same principles as resistive touch screens. They don't measure capacitance. Instead, resistive touchpads rely on pressure to determine where a user glides his or her finger.

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