An optical trackpad is an

input device In computing, an input device is a piece of equipment used to provide data and control signals to an information processing system, such as a computer or information appliance. Examples of input devices include keyboards, mouse, scanners, cameras ...

based on an optical sensor, which detects the displacement of a finger that is moving on top of it. The sensor is used typically in

smartphone A smartphone is a portable computer device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, which ...

s, where it replaces the

D-pad A D-pad (short for directional pad or digital pad; officially referred to by Nintendo as a +Control Pad) is a flat, usually thumb-operated, often digital, four-way directional control with one button on each point, found on nearly all modern vid ...

, and in

ultra-portable Subnotebook, also called ultraportable, superportable, or mini notebook, was a marketing term for laptop computers that are smaller and lighter than a typical notebook-sized laptop. Types and sizes As typical laptop sizes have decreased over t ...

ultra-mobile PC An ultra-mobile PC, or ultra-mobile personal computer (UMPC), is a miniature version of a pen computer, a class of laptop whose specifications were launched by Microsoft and Intel in spring 2006. Sony had already made a first attempt in this d ...

s, where it replaces

touchpad A touchpad or trackpad is a pointing device featuring a tactile sensor, a specialized surface that can translate the motion and position of a user's fingers to a relative position on the operating system that is made output to the screen. Touchp ...

pointing stick A pointing stick (or trackpoint, also referred to generically as a nub or nipple) is a small analog stick used as a pointing device typically mounted centrally in a computer keyboard. Like other pointing devices such as mice, touchpads or trac ...

s or

trackball A trackball is a pointing device consisting of a ball held by a socket containing sensors to detect a rotation of the ball about two axes—like an upside-down ball mouse with an exposed protruding ball. Users roll the ball to position the on-s ...

s as pointing device. The main advantages over a D-pad are: * It can track movements in 360 degrees and with varying speeds. * It uses space efficiently, without the need for small buttons that are difficult to press. Next to browsing through menus, it can drive a mouse cursor in point&click interfaces. In comparison with

s, it detects actual skin displacement, instead of displacement of the center of the area being touched, and more similar to pointing sticks or compact trackballs by using experience, but with less physical feedback.

References

{{Comp-hardware-stub Pointing_devices