View source for Touchpad

{{Short description|Type of pointing device}}
[[File:Acer CB5-311 series touchpad.jpg|thumb|Closeup of a touchpad on an [[Acer Inc.|Acer]] CB5-311 laptop]]
[[File:Macbook touchpad.jpg|thumb|Closeup of a touchpad on a [[MacBook (2015–2019)|MacBook]] 2015 laptop]]
[[File:Touchpad at keyboard G80-11900 by Cherry GmbH.jpg|thumb|[[Computer keyboard]] with integrated touchpad made by [[Cherry AG|Cherry]]]]
A '''touchpad''' or '''trackpad''' is a type of [[pointing device]]. Its largest component is a tactile sensor: an electronic device with a flat surface that detects the position and motion of a user's fingers, and translates them into 2D motion to control a [[Cursor (user interface)#Pointer|pointer]] in a [[graphical user interface]]. Touchpads are common on [[Laptop|laptop computer]]s, contrasted with [[desktop computer]]s, with which [[Computer mouse|mice]] are more prevalent. Trackpads are sometimes used with desktop setups where desk space is scarce. Wireless touchpads are also available, as detached accessories. Due to the ability of trackpads to be made small, they were additionally used on [[personal digital assistant]]s (PDAs) and some [[portable media player]]s.

== Operation and function ==
Touchpads operate in several ways, including [[capacitive sensing]] or [[resistive touchscreen]]. The most common technology used in the 2010s senses the change of [[capacitance]] where a finger touches the pad. Capacitance-based touchpads will not sense the tip of a pencil or other similar ungrounded or non-conducting implements. Fingers insulated by a glove may also be problematic, and capacitive touchpads are rarely used as pointing devices for medical hardware.<ref>{{Cite web|title=VersaPad Plus resistive touchpads target medical, rugged environments|url=https://www.microcontrollertips.com/versapad-plus-resistive-touchpad-touchpads-medical-rugged-environments/|access-date=2021-07-06|website=www.microcontrollertips.com}}</ref>

Like [[touchscreen|touchscreens]], touchpads sense absolute position but their resolution is limited by their size. For common use as a pointer device, the dragging motion of a finger is translated into a finer, relative motion of the cursor on the output to the display on the operating system, analogous to the handling of a [[mouse (computing)|mouse]] that is lifted and put back on a surface. Hardware buttons equivalent to a standard mouse's left and right buttons are sometimes positioned adjacent to the touchpad.

Some touchpads and associated [[device driver]] software may interpret tapping the pad as a [[mouse click]], and a tap followed by a continuous pointing motion (a "click-and-a-half") can indicate dragging.<ref name="MacBook">{{cite web |title=Tap and drag | url=http://movies.apple.com/movies/us/apple/mac/macbookair/2008/apple_macbookair_clickdrag_20080115_r320-13cie.mov| publisher=Apple.com}}</ref> Tactile touchpads allow for clicking and dragging by incorporating button functionality into the surface of the touchpad itself.<ref name="The Tactile Touchpad">{{cite web|url=http://www.sigchi.org/chi97/proceedings/short-talk/sm.htm|title=The Tactile Touchpad|publisher=sigchi.com|access-date=2011-03-21|archive-date=2011-10-01|archive-url=https://web.archive.org/web/20111001071602/http://www.sigchi.org/chi97/proceedings/short-talk/sm.htm|url-status=dead}}</ref><ref name="yorku.ca">{{cite web |url=http://www.yorku.ca/mack/p336-mackenzie.pdf|title=A Comparison of Three Selection Techniques for Touchpads| publisher=yorku.ca}}</ref> To select, one presses down on the touchpad instead of a physical button. To drag, instead of performing the "click-and-a-half" technique, the user presses down while on the object, drags without releasing pressure, and lets go when done. Touchpad drivers can also allow the use of multiple fingers to emulate the other mouse buttons (commonly two-finger tapping for right click).

Touchpads are called clickpads if they rely on software buttons rather than physical buttons. Physically the whole clickpad formed a button, logically the driver interprets a click as a left or right button click depending on the placement of fingers.<ref>{{Cite web |title=Libinput features: Clickpad software button behavior |url=https://wayland.freedesktop.org/libinput/doc/latest/clickpad-softbuttons.html |publisher=wayland.freedesktop.org}}</ref>

Some touchpads have "hotspots", locations on the touchpad used for functionality beyond a mouse. For example, on certain touchpads, moving the finger along an edge of the touch pad will act as a [[scroll wheel]], controlling the [[scrollbar]] and scrolling the [[Window (computing)|window]] that has the [[Focus (computing)|focus]], vertically or horizontally. Many touchpads use two-finger dragging for [[Scrolling TrackPad|scrolling]]. Also, some touchpad drivers support tap zones, regions where a tap will execute a function, for example, pausing a media player or launching an [[Application software|application]]. All of these functions are implemented in the touchpad [[device driver]] software, and can be disabled.

== History ==
In 1980, [[Xerox]] offered one of the first, if not {{em|the}} first, touchpads on a computer system with their [[Xerox 860]], a word processing workstation aimed at medium- and large-sized businesses.<ref name=star /><ref>{{cite book | last=Grünberg | first=Serge | author2=Claudine Paquot | date=2006 | url=https://books.google.com/books?id=xuYcAQAAIAAJ&q=%22xerox%20860%22%20%22touch%20pad%22 | title=David Cronenberg: Interviews with Serge Grünberg | publisher=Plexus Publishing | page=79 | isbn=9780859653763 | via=Google Books}}</ref> Embedded on the [[Xerox 860]]'s keyboard, to the right of the keys, is the circular touchpad, which Xerox dubbed the "Cat" (short for ''capacitance-activated transducer''). Xerox offered the Cat as an alternative input method for selecting strings of text to copy, delete, insert, or move around the document.<ref>{{cite book | last=Williford | first=J.&nbsp;M. | date=1984 | url=https://bitsavers.org/pdf/xerox/860/Word_Processing_on_the_Xerox_860_1984.pdf#page=25 | title=Word Processing on the Xerox 860 | publisher=John Wiley & Sons | pages=15–16 | isbn=0-471-88257-7 | via=Bitsavers.org}}</ref><ref>{{cite book | last=Flores | first=Ivan | date=1983 | url=https://books.google.com/books?id=MweWohWJRykC | title=Word Processing Handbook | publisher=Van Nostrand Reinhold Company | page=177 | isbn=9780442225261 | via=Google Books}}</ref><ref name=star>{{cite journal | last=Valigra | first=L. | date=June 1981 | url=https://books.google.com/books?id=ZWhKAQAAIAAJ&q=%22xerox+860%22+%22cat%22 | title=Xerox's 'Star' shines on professionals | journal=Mini-Micro Systems | publisher=Reed Business Information | volume=14 | issue=6 | pages=23 ''et seq'' | via=Gale}}</ref>{{rp|30}}

By 1982, [[Apollo Computer|Apollo]] desktop computers were equipped with a touchpad on the right side of the keyboard.<ref name="apollo-started">{{cite book|publisher=Apollo Computer|title=Getting Started With Your DOMAIN System|year=1983 }}</ref> Introduced a year later, in 1983, the first battery-powered clamshell laptop, the [[Gavilan SC]] included a touchpad, which was mounted above its keyboard, rather than below, which became the norm.<ref name="design198311_gavilan">{{ cite magazine | url=https://archive.org/details/sim_design_1983-11_419/page/n21/mode/1up | title=Briefcase computer | magazine=Design | date=November 1983 | access-date=16 March 2022 | pages=20 | quote=The Gavilan portable computer uses a touch-sensitive panel between its text-entry keyboard and its liquid-crystal display. Moving your finger around on this shifts the cursor on the screen to select commands from a menu. }}</ref>

[[Psion (computers)|Psion]]'s [[Psion MC series|MC 200/400/600/WORD Series]],<ref name="psion">{{cite web|title=GUIdebook Psion MC Series brochure|url=http://www.guidebookgallery.org/ads/magazines/symbian/mc400brochure|publisher=guidebookgallery.org}}</ref> introduced in 1989, came with a new mouse-replacing input device similar to a touchpad,<ref name="psion1">{{cite web|title=GUIdebook Psion MC Series brochure, page 4|url=http://www.guidebookgallery.org/ads/magazines/symbian/mc400brochure/pics/05|publisher=guidebookgallery.org}}</ref> although more closely resembling a graphics tablet, as the cursor was positioned by clicking on a specific point on the pad, instead of moving it in the direction of a stroke.<ref name="newcomputerexpress19891202_psions">{{ cite magazine | url=https://archive.org/details/NH2021_New_Computer_Express_Issue056.pdf/page/66/mode/2up | title=Psions of the Times | magazine=New Computer Express | date=2 December 1989 | access-date=20 March 2022 | last1=Booth | first1=Neil | pages=66–67 | quote=You put your finger on a small rectangular panel, and the cursor appears on screen. Move your finger around the panel, say from the bottom left of the panel to the centre, and the cursor moves from the bottom left to the centre of the screen in parallel. }}</ref>

Laptops with touchpads were launched by [[Olivetti]] and [[Triumph-Adler]] in 1992.<ref>{{Cite web |url=http://www.vintage-computer.com/vcforum/showthread.php?49668-First-Laptops-with-Touchpad-as-Mouse-replacement |title=Olivetti S20, D33 and identically Triumph-Adler Walkstation 386, Walkstation 386SX |access-date=2015-10-26 |archive-date=2016-03-04 |archive-url=https://web.archive.org/web/20160304092833/http://www.vintage-computer.com/vcforum/showthread.php?49668-First-Laptops-with-Touchpad-as-Mouse-replacement |url-status=dead }}</ref> [[Cirque Corporation|Cirque]] introduced the first widely available touchpad, branded as GlidePoint, in 1994.<ref name="diehl_stanford">{{cite magazine|last=Diehl|first=Stanford|author2=Lennon, Anthony J.|author3=McDonough, John|date=Oct 1995|title=Touchpads to Navigate By|url=https://vintageapple.org/byte/pdf/199510_Byte_Magazine_Vol_20-10_The_PC_is_Dead.pdf|magazine=[[Byte (magazine)|Byte]]|publisher=Green Publishing|issue=October 1995|page=150|issn=0360-5280}}</ref><ref>{{Cite web|title=[Products {{!}} Our Technology {{!}} High-Sensitivity Capacitive Technology] Alps Alpine – Electronic Components and Automotive Infotainment|url=https://tech.alpsalpine.com/e/info/technology/tec_capacitance/|access-date=2021-07-06|website=tech.alpsalpine.com}}</ref> [[Apple Inc.|Apple]] introduced touchpads with modern placing in the [[PowerBook 500]] series in 1994, using Cirque's GlidePoint technology,<ref>Thryft, Ann R. "More Than a Mouse," Computer Product Development, EBN Extra, November 14, 1994, pp. E16 – E20</ref><ref>{{Cite news|date=1994-05-16|title=Blackbird: The PowerBook 500 Series|language=en-US|work=Low End Mac|url=http://lowendmac.com/1994/blackbird-the-powerbook-500-series/|access-date=2017-07-09}}</ref> which Apple refers to as a "trackpad"; it replaced the [[trackball]] of previous [[PowerBook]] models. Since 2008, Apple's revisions of the [[MacBook]] and [[MacBook Pro]] incorporated a "Tactile Touchpad" design with a button integrated into the tracking surface<ref name="The Tactile Touchpad" /><ref name="yorku.ca" /><ref>{{cite web|title=MacBook design|url=https://www.apple.com/macbook/design.html|publisher=Apple.com}}</ref> (the lower part of the touchpad surface acts as a clickable button).<ref name="CNET June 9 review">{{cite web|last=Ackerman|first=Dan|author-link=Dan Ackerman|date=June 10, 2009|title=Apple MacBook Pro Summer 2009 (Core 2 Duo 2.26&nbsp;GHz, 2GB RAM, 160GB HDD, Nvidia GeForce 9400M, 13-inch)|url=http://reviews.cnet.com/laptops/apple-macbook-pro-summer/4505-3121_7-33676744.html?tag=mncol;lst|access-date=April 11, 2010|publisher=[[CNET Networks|CNET]]}}</ref>

Another early adopter of the GlidePoint pointing device was Sharp.<ref name="diehl_stanford" /> Later, [[Synaptics]] introduced their touchpad into the marketplace, branded the TouchPad, and [[Epson]] was an early adopter of this product with their [[Epson ActionNote|ActionNote]].<ref name="diehl_stanford" />
As touchpads began to be introduced in laptops in the 1990s, there was often confusion as to what the product should be called. No consistent term was used, and references varied, such as: glidepoint, touch sensitive input device, touchpad, trackpad, and pointing device.<ref>{{cite magazine |title=A WinBook for the Fussy |year=1995|magazine=Windows Magazine|issue=Dec 95|page=105}}</ref><ref>{{cite journal |title=Sharp Unveils Line of Notebooks |journal=Westchester County Business Journal|issue= November 20, 1995 |year=1995 }}</ref><ref>{{cite journal |last1=Malloy |first1=Rich |last2= Crabb |first2=Don |date=October 1995 |title=Power Packed Power Books |journal= Mobile Office |issue=October 1995 |pages=44–52 |location=New York, NY }}</ref>

Users were often presented with the option to purchase a [[pointing stick]], touchpad, or [[trackball]]. Combinations of the devices were common, though touchpads and trackballs were rarely included together.<ref>{{cite journal |last1=Jerome |first1=Marty |year=1995 |title=Lightweight, Low-Cost Challenger |journal=[[PC Computing]] |issue=December 1995 |page=96}}</ref> Since the early 2000s, touchpads have become the dominant laptop pointing device as most consumer laptops produced during this period and beyond includes only touchpads, displacing the pointing stick.

== Use in devices ==
[[File:Curve8520TrackPad.jpg|thumb|A [[BlackBerry Curve]] [[smartphone]] with an optical trackpad (circled in red).]]
[[File:Surface_RT.jpg|thumb|A [[Microsoft Surface]] [[tablet computer|tablet]]. The touchpad is the rectangle near the bottom of the keyboard.]]
Touchpads are primarily used in self-contained portable [[laptop]] computers and do not require a flat surface near the machine. The touchpad is close to the keyboard, and relatively short finger movements are required to move the cursor across the display screen; while advantageous, this also makes it possible for a user's palm or wrist to move the mouse cursor accidentally while typing. Laptops today feature [[Multi-touch|multitouch]] touchpads that can sense in some cases up to five fingers simultaneously, providing more options for input, such as the ability to bring up the [[context menu]] by tapping two fingers, dragging two fingers for scrolling, or gestures for zoom in/out or rotate. The touchpads with physical buttons now are only hi-end business/professional laptops option.

One-dimensional touchpads are the primary control interface for menu navigation on [[iPod Classic]] portable music players and additional input method on some [[Wacom]] digitizer tablets, where they are referred to as "click wheels", since they only sense motion along one axis, which is wrapped around like a wheel. [[Creative Labs]] also uses a touchpad for their [[Creative Zen|Zen]] line of [[MP3 player]]s, beginning with the Zen Touch. The second-generation [[Microsoft]] [[Zune]] product line (the [[Zune 80, 120|Zune 80/120]] and [[Zune 4, 8, 16|Zune 4/8]]) uses touch for the [[Zune Pad]].

Touchpads also exist for desktop computers as an external peripheral, albeit rarely seen. But touchpad layer can be integrated with [[graphics tablet]] as additional input option.

External computer keyboards can be equipped with integrated touchpads<ref>{{Cite web|last=Yu|first=Justin|title=This Logitech keyboard and touch pad would like the full attention of your hands|url=https://www.cnet.com/reviews/logitech-wireless-all-in-one-keyboard-tk820-review/|access-date=2021-07-06|website=CNET|language=en}}</ref> (particularly keyboards oriented for [[HTPC]] use), and some keyboards can have only touch input surface instead of hardware buttons (a typical solution for clean rooms).<ref>{{Cite web|last=GmbH|first=Systec & Solutions|title=Medical keyboard and stainless steel tablet|url=https://www.systec-solutions.com/en/products/medical-keyboard-and-stainless-steel-tablet|access-date=2021-07-06|website=www.systec-solutions.com|language=en-US}}</ref>

[[Optical trackpad]]s primary can be used as part of ultraportable electronics; some handheld laptops and early smartphones can be equipped with optical trackpads.

On September 9, 2024, Apple unveiled the [[IPhone 16|iPhone 16, iPhone 16 Plus]], [[IPhone 16 Pro|iPhone 16 Pro and iPhone 16 Pro Max]] to feature the single one-dimensional trackpad next to the side button called "Camera Control" which allows the users to take an easier way to take a photos and videos, the force sensor to distinguish between the firm press and the light press and the capacitance touch sensor to distinguish sliding with finger for adjusting the zoom, exposure or depth-of-field.<ref>{{Cite web |title=Apple introduces iPhone 16 and iPhone 16 Plus |url=https://www.apple.com/newsroom/2024/09/apple-introduces-iphone-16-and-iphone-16-plus/ |access-date=2024-09-14 |website=Apple Newsroom |language=en-US}}</ref><ref>{{Cite web |title=Apple debuts iPhone 16 Pro and iPhone 16 Pro Max |url=https://www.apple.com/newsroom/2024/09/apple-debuts-iphone-16-pro-and-iphone-16-pro-max/ |access-date=2024-09-14 |website=Apple Newsroom |language=en-US}}</ref>

== Theory of operation ==
There are two principal means by which touchpads work: the matrix approach and the capacitive shunt method.{{citation needed|date=March 2011}} In the matrix approach, a series of [[Electrical conductor|conductors]] are arranged in an array of parallel lines in two layers, separated by an [[Insulator (electrical)|insulator]] and crossing each other at [[right angle]]s to form a grid. A high frequency signal is applied sequentially between pairs in this two-dimensional grid array. The current that passes between the nodes is proportional to the [[capacitance]]. When a [[virtual ground]], such as a finger, is placed over one of the intersections between the conductive layer some of the electrical field is [[Shunt (electrical)|shunted]] to this ground point, resulting in a change in the apparent capacitance at that location. This method received {{US patent|5305017}} awarded to George Gerpheide in April 1994.

The capacitive shunt method, described in an application note by manufacturer [[Analog Devices]],<ref name="capacitiveshunt">{{cite web |url=http://www.analog.com/media/en/technical-documentation/data-sheets/AD7142.pdf |title=Analog Devices' Capacitive Shunt Method| publisher= analog.com}}</ref> senses the change in [[capacitance]] between a transmitter and receiver that are on opposite sides of the sensor. The transmitter creates an electric field which oscillates at 200–300&nbsp;kHz. If a ground point, such as the finger, is placed between the transmitter and receiver, some of the field lines are shunted away, decreasing the apparent capacitance.

[[Optical trackpad|Trackpads]] such as those found in some Blackberry smartphones work optically, like an optical [[computer mouse]].

== Manufacturing ==

Major manufacturers include:{{Citation needed|date=July 2021}}
* [[Alps Electric]]
* Elan Microelectronics
* [[Cirque Corporation]]
* [[Synaptics]]

== See also ==
{{Commons category|Touchpads}}
{{Wiktionary|touchpad|trackpad|touchscreen}}
* [[Capacitive sensing]]
* [[Graphics tablet]]
* [[Kaoss Pad]]
* [[List of touch input manufacturers]]
* [[Magic Trackpad]]
* [[Multi-touch]]
* [[Pointing stick]]

== References ==
{{Reflist|30em}}

== External links ==
* [http://ruetersward.com/biblio.html Annotated Bibliography of References to Gestures, Touchscreens, and Pen Computing]
* {{YouTube|4xnqKdWMa_8|Notes on the History of Pen-based Computing}}

{{Basic computer components}}
{{Authority control}}

[[Category:History of human–computer interaction]]
[[Category:Pointing devices]]