Touchscreen - Wikipedia, the free encyclopedia
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`Page 1 of 13
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`Touchscreen
`
`From Wikipedia, the free encyclopedia
`
`A touchscreen is an input device normally layered on the top of an
`electronic visual display of an information processing system. A user
`can give input or control the information processing system through
`simple or multi-touch gestures by touching the screen with a special
`stylus/pen and-or one or more fingers.[1] Some touchscreens use an
`ordinary or specially coated gloves to work while others use a special
`stylus/pen only. The user can use the touchscreen to react to what is
`displayed and to control how it is displayed (for example by zooming
`the text size).
`
`The touchscreen enables the user to interact directly with what is
`displayed, rather than using a mouse, touchpad, or any other
`intermediate device (other than a stylus, which is optional for most
`modern touchscreens).
`
`Interactive table, Ideen 2020 exposition,
`2013
`
`Touchscreens are common in devices such as game consoles, personal
`computers, tablet computers, and smartphones. They can also be attached to
`computers or, as terminals, to networks. They also play a prominent role in
`the design of digital appliances such as personal digital assistants (PDAs),
`GPS navigation devices, mobile phones, and video games and some books
`(E-books).
`
`The popularity of smartphones, tablets, and many types of information
`appliances is driving the demand and acceptance of common touchscreens
`for portable and functional electronics. Touchscreens are found in the
`medical field and in heavy industry, as well as for automated teller machines
`(ATMs), and kiosks such as museum displays or room automation, where
`keyboard and mouse systems do not allow a suitably intuitive, rapid, or
`accurate interaction by the user with the display's content.
`
`Historically, the touchscreen sensor and its accompanying controller-based
`firmware have been made available by a wide array of after-market system
`integrators, and not by display, chip, or motherboard manufacturers. Display
`manufacturers and chip manufacturers worldwide have acknowledged the
`trend toward acceptance of touchscreens as a highly desirable user interface
`component and have begun to integrate touchscreens into the fundamental
`design of their products.
`
`Contents
`◾ 1 History
`◾ 2 Technologies
`◾ 2.1 Resistive
`◾ 2.2 Surface acoustic wave
`◾ 2.3 Capacitive
`◾ 2.3.1 Surface capacitance
`◾ 2.3.2 Projected capacitance
`
`HP Series 100 HP-150 c. 1983, the
`earliest commercial touchscreen
`computer
`
`The IBM Simon Personal
`Communicator, c. 1993, the first
`touchscreen phone
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`◾ 2.3.3 Mutual capacitance
`◾ 2.3.3.1 Self-capacitance
`◾ 2.3.3.1.1 Use of styli on capacitive screens
`◾ 2.4 Infrared grid
`◾ 2.5 Infrared acrylic projection
`◾ 2.6 Optical imaging
`◾ 2.7 Dispersive signal technology
`◾ 2.8 Acoustic pulse recognition
`◾ 3 Construction
`◾ 4 Development
`◾ 5 Ergonomics and usage
`◾ 5.1 Touchscreen accuracy
`◾ 5.2 Hand position, digit used and switching
`◾ 5.3 Combined with haptics
`◾ 5.4 "Gorilla arm"
`◾ 5.5 Fingerprints
`◾ 6 See also
`◾ 7 Notes
`◾ 8 References
`◾ 9 External links
`
`History
`
`E.A. Johnson described his work on capacitive touchscreens in a short article
`which is published in 1965[6] and then more fully—along with photographs
`and diagrams—in an article published in 1967.[7] A description of the
`applicability of the touch technology for air traffic control was described in
`an article published in 1968.[8] Frank Beck and Bent Stumpe, engineers from
`CERN, developed a transparent touchscreen in the early 1970s and it was
`manufactured by CERN and put to use in 1973.[9] This touchscreen was
`based on Bent Stumpe's work at a television factory in the early 1960s. A
`resistive touchscreen was developed by American inventor G. Samuel Hurst
`who received US patent #3,911,215 on October 7, 1975.[10] The first version
`was produced in 1982.[11]
`
`Apple iPad, a tablet computer with a
`touchscreen
`
`In 1972, a group at the University of Illinois filed for a patent on an optical
`touchscreen.[12] These touch screens became a standard part of the
`Magnavox Plato IV Student Terminal. Thousands of these were built for the
`PLATO IV system. These touchscreens had a crossed array of 16 by 16
`infrared position sensors, each composed of an LED on one edge of the
`screen and a matched phototransistor on the other edge, all mounted in front
`of a monochrome plasma display panel. This arrangement can sense any
`fingertip-sized opaque object in close proximity to the screen. A similar
`touchscreen was used on the HP-150 starting in 1983; this was one of the
`world's earliest commercial touchscreen computers.[13] HP mounted their infrared transmitters and receivers around
`the bezel of a 9" Sony Cathode Ray Tube (CRT).
`
`The prototype[2] x-y mutual
`capacitance touchscreen (left)
`developed at CERN[3][4] in 1977 by
`Bent Stumpe, a Danish electronics
`engineer, for the control room of
`CERN’s accelerator SPS (Super
`Proton Synchrotron). This was a
`further development of the self-
`capacitance screen (right), also
`developed by Stumpe at CERN[5] in
`1972.
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`In 1985, Sega released the Terebi Oekaki, also known as the Sega Graphic Board, for the SG-1000 video game
`console and SC-3000 home computer. It consisted of a plastic pen and a plastic board with a transparent window
`where the pen presses are detected. It was used primarily for a drawing software application.[14]
`
`In the early 1980s, General Motors tasked its Delco Electronics division with a project aimed at replacing an
`automobile's non essential functions (i.e. other than throttle, transmission, braking and steering) from mechanical or
`electro-mechanical systems with solid state alternatives wherever possible. The finished device was dubbed the
`ECC for "Electronic Control Center", a digital computer and software control system hardwired to various
`peripheral sensors, servos, solenoids, antenna and a monochrome CRT touchscreen that functioned both as display
`and sole method of input.[15] The ECC replaced the traditional mechanical stereo, fan, heater and air conditioner
`controls and displays, and was capable of providing very detailed and specific information about the vehicle's
`cumulative and current operating status in real time. The ECC was standard equipment on the 1985–89 Buick
`Riviera and later the 1988–89 Buick Reatta, but was unpopular with consumers partly due to technophobia on
`behalf of some traditional Buick customers, but mostly because of costly to repair technical problems suffered by
`the ECC's touchscreen which being the sole access method, would render climate control or stereo operation
`impossible.[16]
`
`Multi-touch technology began in 1982, when the University of Toronto's Input Research Group developed the first
`human-input multi-touch system, using a frosted-glass panel with a camera placed behind the glass. In 1985, the
`University of Toronto group including Bill Buxton developed a multi-touch tablet that used capacitance rather than
`bulky camera-based optical sensing systems (see History of multi-touch).
`
`In 1986, the first graphical point of sale software was demonstrated on the 16-bit Atari 520ST color computer. It
`featured a color touchscreen widget-driven interface.[17] The ViewTouch[18] point of sale software was first shown
`by its developer, Gene Mosher, at Fall Comdex, 1986, in Las Vegas, Nevada to visitors at the Atari Computer
`demonstration area and was the first commercially available POS system with a widget-driven color graphic
`touchscreen interface.[19]
`
`In 1987, Casio launched the Casio PB-1000 pocket computer with a touchscreen consisting of a 4x4 matrix,
`resulting in 16 touch areas in its small LCD graphic screen.
`
`Sears et al. (1990)[20] gave a review of academic research on single and multi-touch human–computer interaction of
`the time, describing gestures such as rotating knobs, adjusting sliders, and swiping the screen to activate a switch (or
`a U-shaped gesture for a toggle switch). The University of Maryland Human – Computer Interaction Lab team
`developed and studied small touchscreen keyboards (including a study that showed that users could type at 25 wpm
`for a touchscreen keyboard compared with 58 wpm for a standard keyboard), thereby paving the way for the
`touchscreen keyboards on mobile devices. They also designed and implemented multitouch gestures such as
`selecting a range of a line, connecting objects, and a "tap-click" gesture to select while maintaining location with
`another finger.
`
`In c. 1991–92, the Sun Star7 prototype PDA implemented a touchscreen with inertial scrolling.[21] In 1993, the IBM
`Simon—the first touchscreen phone—was released.
`
`An early attempt at a handheld game console with touchscreen controls was Sega's intended successor to the Game
`Gear, though the device was ultimately shelved and never released due to the expensive cost of touchscreen
`technology in the early 1990s. Touchscreens would not be popularly used for video games until the release of the
`Nintendo DS in 2004.[22] Until recently, most consumer touchscreens could only sense one point of contact at a
`time, and few have had the capability to sense how hard one is touching. This has changed with the
`commercialization of multi-touch technology.
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`Technologies
`
`There are a variety of touchscreen technologies that have different methods of sensing touch.[20]
`
`Resistive
`
`A resistive touchscreen panel comprises several layers, the most important of which are two thin, transparent
`electrically-resistive layers separated by a thin space. These layers face each other with a thin gap between. The top
`screen (the screen that is touched) has a coating on the underside surface of the screen. Just beneath it is a similar
`resistive layer on top of its substrate. One layer has conductive connections along its sides, the other along top and
`bottom. A voltage is applied to one layer, and sensed by the other. When an object, such as a fingertip or stylus tip,
`presses down onto the outer surface, the two layers touch to become connected at that point: The panel then behaves
`as a pair of voltage dividers, one axis at a time. By rapidly switching between each layer, the position of a pressure
`on the screen can be read.
`
`Resistive touch is used in restaurants, factories and hospitals due to its high resistance to liquids and contaminants.
`A major benefit of resistive touch technology is its low cost. Additionally, as only sufficient pressure is necessary
`for the touch to be sensed, they may be used with gloves on, or by using anything rigid as a finger/stylus substitute.
`Disadvantages include the need to press down, and a risk of damage by sharp objects. Resistive touchscreens also
`suffer from poorer contrast, due to having additional reflections from the extra layers of material (separated by an
`air gap) placed over the screen.[23] This is the type of touchscreen used by Nintendo in DS consoles and the WiiU.[24]
`
`Surface acoustic wave
`
`Surface acoustic wave (SAW) technology also uses ultrasonic waves that pass over the touchscreen panel. When the
`panel is touched, a portion of the wave is absorbed. This change in the ultrasonic waves registers the position of the
`touch event and sends this information to the controller for processing. Surface acoustic wave touchscreen panels
`can be damaged by outside elements. Contaminants on the surface can also interfere with the functionality of the
`touchscreen.
`
`Capacitive
`
`A capacitive touchscreen panel consists of an insulator such as glass, coated
`with a transparent conductor such as indium tin oxide (ITO).[25] As the
`human body is also an electrical conductor, touching the surface of the
`screen results in a distortion of the screen's electrostatic field, measurable as
`a change in capacitance. Different technologies may be used to determine
`the location of the touch. The location is then sent to the controller for
`processing.
`
`Unlike a resistive touchscreen, one cannot use a capacitive touchscreen
`through most types of electrically insulating material, such as gloves. This
`disadvantage especially affects usability in consumer electronics, such as
`touch tablet PCs and capacitive smartphones in cold weather. It can be
`overcome with a special capacitive stylus, or a special-application glove with an embroidered patch of conductive
`thread passing through it and contacting the user's fingertip.
`
`Capacitive touchscreen of a mobile
`phone
`
`The largest capacitive display manufacturers continue to develop thinner and more accurate touchscreens, with
`touchscreens for mobile devices now being produced with 'in-cell' technology that eliminates a layer, such as
`Samsung's Super AMOLED screens, by building the capacitors inside the display itself. This type of touchscreen
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`reduces the visible distance (within millimetres) between the user's finger and what the user is touching on the
`screen, creating a more direct contact with the content displayed and enabling taps and gestures to be more
`responsive.
`
`A simple parallel plate capacitor has two conductors separated by a dielectric layer. Most of the energy in this
`system is concentrated directly between the plates. Some of the energy spills over into the area outside the plates,
`and the electric field lines associated with this effect are called fringing fields. Part of the challenge of making a
`practical capacitive sensor is to design a set of printed circuit traces which direct fringing fields into an active
`sensing area accessible to a user. A parallel plate capacitor is not a good choice for such a sensor pattern. Placing a
`finger near fringing electric fields adds conductive surface area to the capacitive system. The additional charge
`storage capacity added by the finger is known as finger capacitance, CF. The capacitance of the sensor without a
`finger present is denoted as CP in this article, which stands for parasitic capacitance.
`
`Surface capacitance
`
`In this basic technology, only one side of the insulator is coated with a conductive layer. A small voltage is applied
`to the layer, resulting in a uniform electrostatic field. When a conductor, such as a human finger, touches the
`uncoated surface, a capacitor is dynamically formed. The sensor's controller can determine the location of the touch
`indirectly from the change in the capacitance as measured from the four corners of the panel. As it has no moving
`parts, it is moderately durable but has limited resolution, is prone to false signals from parasitic capacitive coupling,
`and needs calibration during manufacture. It is therefore most often used in simple applications such as industrial
`controls and kiosks.[26]
`
`Projected capacitance
`
`Projected Capacitive Touch (PCT; also PCAP) technology is a variant of
`capacitive touch technology. All PCT touch screens are made up of a matrix
`of rows and columns of conductive material, layered on sheets of glass. This
`can be done either by etching a single conductive layer to form a grid pattern
`of electrodes, or by etching two separate, perpendicular layers of conductive
`material with parallel lines or tracks to form a grid. Voltage applied to this
`grid creates a uniform electrostatic field, which can be measured. When a
`conductive object, such as a finger, comes into contact with a PCT panel, it
`distorts the local electrostatic field at that point. This is measurable as a
`change in capacitance. If a finger bridges the gap between two of the
`"tracks", the charge field is further interrupted and detected by the controller.
`The capacitance can be changed and measured at every individual point on
`the grid (intersection). Therefore, this system is able to accurately track
`touches.[27] Due to the top layer of a PCT being glass, it is a more robust
`solution than less costly resistive touch technology. Additionally, unlike
`traditional capacitive touch technology, it is possible for a PCT system to
`sense a passive stylus or gloved fingers. However, moisture on the surface of the panel, high humidity, or collected
`dust can interfere with the performance of a PCT system. There are two types of PCT: mutual capacitance and self-
`capacitance.
`
`Back side of a Multitouch Globe,
`based on Projected Capacitive Touch
`(PCT) technology
`
`Mutual capacitance
`
`This is a common PCT approach, which makes use of the fact that most conductive objects are able to hold a charge
`if they are very close together. In mutual capacitive sensors, a capacitor is inherently formed by the row trace and
`column trace at each intersection of the grid. A 16-by-14 array, for example, would have 224 independent
`capacitors. A voltage is applied to the rows or columns. Bringing a finger or conductive stylus close to the surface
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`of the sensor changes the local electrostatic field which reduces the mutual
`capacitance. The capacitance change at every individual point on the grid
`can be measured to accurately determine the touch location by measuring the
`voltage in the other axis. Mutual capacitance allows multi-touch operation
`where multiple fingers, palms or styli can be accurately tracked at the same
`time.
`
`Self-capacitance
`
`Self-capacitance sensors can have the same X-Y grid as mutual capacitance
`sensors, but the columns and rows operate independently. With self-
`capacitance, the capacitive load of a finger is measured on each column or
`row electrode by a current meter. This method produces a stronger signal
`than mutual capacitance, but it is unable to resolve accurately more than one
`finger, which results in "ghosting", or misplaced location sensing.
`
`Use of styli on capacitive screens
`
`Capacitive touchscreens don't necessarily need to be operated by a finger,
`but the special styli required can be quite expensive to purchase.
`
`Schema of projected-capacitive
`touchscreen
`
`Infrared grid
`
`An infrared touchscreen uses an array of X-Y infrared LED and
`photodetector pairs around the edges of the screen to detect a disruption in
`the pattern of LED beams. These LED beams cross each other in vertical and
`horizontal patterns. This helps the sensors pick up the exact location of the
`touch. A major benefit of such a system is that it can detect essentially any
`input including a finger, gloved finger, stylus or pen. It is generally used in
`outdoor applications and point of sale systems which can not rely on a
`conductor (such as a bare finger) to activate the touchscreen. Unlike
`capacitive touchscreens, infrared touchscreens do not require any patterning
`on the glass which increases durability and optical clarity of the overall
`system. Infrared touchscreens are sensitive to dirt/dust that can interfere with
`the IR beams, and suffer from parallax in curved surfaces and accidental
`press when the user hovers his/her finger over the screen while searching for
`the item to be selected.
`
`Infrared acrylic projection
`
`A translucent acrylic sheet is used as a rear projection screen to display
`information. The edges of the acrylic sheet are illuminated by infrared
`LEDs, and infrared cameras are focused on the back of the sheet. Objects
`placed on the sheet are detectable by the cameras. When the sheet is touched
`by the user the deformation results in leakage of infrared light, which peaks
`at the points of maximum pressure indicating the user's touch location.
`Microsoft's PixelSense tables use this technology.
`
`Optical imaging
`
`Infrared sensors mounted around the
`display watch for a user's touchscreen
`input on this PLATO V terminal in
`1981. The monochromatic plasma
`display's characteristic orange glow is
`illustrated.
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`Optical touchscreens are a relatively modern development in touchscreen technology, in which two or more image
`sensors are placed around the edges (mostly the corners) of the screen. Infrared back lights are placed in the
`camera's field of view on the other side of the screen. A touch shows up as a shadow and each pair of cameras can
`then be pinpointed to locate the touch or even measure the size of the touching object (see visual hull). This
`technology is growing in popularity, due to its scalability, versatility, and affordability, especially for bigger units.
`
`Dispersive signal technology
`
`Introduced in 2002, by 3M, this system uses sensors to detect the piezoelectricity in the glass that occurs due to a
`touch. Complex algorithms then interpret this information and provide the actual location of the touch.[28] The
`technology claims to be unaffected by dust and other outside elements, including scratches. Since there is no need
`for additional elements on screen, it also claims to provide excellent optical clarity. Also, since mechanical
`vibrations are used to detect a touch event, any object can be used to generate these events, including fingers and
`stylus. A downside is that after the initial touch the system cannot detect a motionless finger.
`
`Acoustic pulse recognition
`
`The key to this technology is that a touch at any one position on the surface generates a sound wave in the substrate
`which then produces a unique combined sound after being picked up by three or more tiny transducers attached to
`the edges of the touchscreen. The sound is then digitized by the controller and compared to a list of pre-recorded
`sounds for every position on the surface. The cursor position is instantly updated to the touch location. A moving
`touch is tracked by rapid repetition of this process. Extraneous and ambient sounds are ignored since they do not
`match any stored sound profile. The technology differs from other attempts to recognize the position of touch with
`transducers or microphones in using a simple table look-up method, rather than requiring powerful and expensive
`signal processing hardware to attempt to calculate the touch location without any references. As with the dispersive
`signal technology system, a motionless finger cannot be detected after the initial touch. However, for the same
`reason, the touch recognition is not disrupted by any resting objects. The technology was created by SoundTouch
`Ltd in the early 2000s, as described by the patent family EP1852772, and introduced to the market by Tyco
`International's Elo division in 2006 as Acoustic Pulse Recognition.[29] The touchscreen used by Elo is made of
`ordinary glass, giving good durability and optical clarity. APR is usually able to function with scratches and dust on
`the screen with good accuracy. The technology is also well suited to displays that are physically larger.
`Construction
`
`There are several principal ways to build a touchscreen. The key goals are to recognize one or more fingers touching
`a display, to interpret the command that this represents, and to communicate the command to the appropriate
`application.
`
`In the most popular techniques, the capacitive or resistive approach, there are typically four layers:
`
`1. Top polyester coated with a transparent metallic conductive coating on the bottom
`2. Adhesive spacer
`3. Glass layer coated with a transparent metallic conductive coating on the top
`4. Adhesive layer on the backside of the glass for mounting.
`
`When a user touches the surface, the system records the change in the electric current that flows through the display.
`
`Dispersive-signal technology which 3M created in 2002, measures the piezoelectric effect—the voltage generated
`when mechanical force is applied to a material—that occurs chemically when a strengthened glass substrate is
`touched.
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`There are two infrared-based approaches. In one, an array of sensors detects a finger touching or almost touching
`the display, thereby interrupting light beams projected over the screen. In the other, bottom-mounted infrared
`cameras record screen touches.
`
`In each case, the system determines the intended command based on the controls showing on the screen at the time
`and the location of the touch.
`Development
`
`The development of multipoint touchscreens facilitated the tracking of more than one finger on the screen; thus,
`operations that require more than one finger are possible. These devices also allow multiple users to interact with
`the touchscreen simultaneously.
`
`With the growing use of touchscreens, the marginal cost of touchscreen technology is routinely absorbed into the
`products that incorporate it and is nearly eliminated. Touchscreens now have proven reliability. Thus, touchscreen
`displays are found today in airplanes, automobiles, gaming consoles, machine control systems, appliances, and
`handheld display devices including the Nintendo DS and multi-touch enabled cellphones; the touchscreen market
`for mobile devices is projected to produce US$5 billion in 2009.[30]
`
`The ability to accurately point on the screen itself is also advancing with the emerging graphics tablet/screen
`hybrids.
`
`TapSense, announced in October 2011, allows touchscreens to distinguish what part of the hand was used for input,
`such as the fingertip, knuckle and fingernail. This could be used in a variety of ways, for example, to copy and
`paste, to capitalize letters, to activate different drawing modes, and similar.[31][32]
`Ergonomics and usage
`Touchscreen accuracy
`
`Users must be able to accurately select targets on touchscreens, and avoid accidental selection of adjacent targets, to
`effectively use a touchscreen input device. The design of touchscreen interfaces must reflect both technical
`capabilities of the system, ergonomics, cognitive psychology and human physiology.
`
`Guidelines for touchscreen designs were first developed in the 1990s, based on early research and actual use of
`older systems, so assume the use of contemporary sensing technology such as infrared grids. These types of
`touchscreens are highly dependent on the size of the user's fingers, so their guidelines are less relevant for the bulk
`of modern devices, using capacitive or resistive touch technology.[33][34] From the mid-2000s onward, makers of
`operating systems for smartphones have promulgated standards, but these vary between manufacturers, and allow
`for significant variation in size based on technology changes, so are unsuitable from a human factors perspective.[35]
`[36][37]
`
`Much more important is the accuracy humans have in selecting targets with their finger or a pen stylus. The
`accuracy of user selection varies by position on the screen. Users are most accurate at the center, less so at the left
`and right edges, and much less accurate at the top and especially bottom edges. The R95 accuracy varies from 7 mm
`in the center, to 12 mm in the lower corners.[38][39][40][41][42] Users are subconsciously aware of this, and are also
`slightly slower, taking more time to select smaller targets, and any at the edges and corners.[43]
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`This inaccuracy is a result of parallax, visual acuity and the speed of the feedback loop between the eyes and
`fingers. The precision of the human finger alone is much, much higher than this, so when assistive technologies are
`provided such as on-screen magnifiers, users can move their finger (once in contact with the screen) with precision
`as small as 0.1 mm.[44]
`
`Hand position, digit used and switching
`
`Users of handheld and portable touchscreen devices hold them in a variety of ways, and routinely change their
`method of holding and selection to suit the position and type of input. There are four basic types of handheld
`interaction:
`
`1. Holding at least in part with both hands, tapping with a single thumb
`2. Holding with one hand, tapping with the finger (or rarely, thumb) of another hand
`3. Holding the device in one hand, and tapping with the thumb from that hand
`4. Holding with two hands and tapping with both thumbs
`
`Use rates vary widely. While two-thumb tapping is encountered rarely (1-3%) for many general interactions, it is
`used for 41% of typing interaction.[45]
`
`In addition, devices are often placed on surfaces (desks or tables) and tablets especially are used in stands. The user
`may point, select or gesture in these cases with their finger or thumb, and also varies the use.[46]
`
`Combined with haptics
`
`Touchscreens are often used with haptic response systems. A common example of this technology is the vibratory
`feedback provided when a button on the touchscreen is tapped. Haptics are used to improve the user's experience
`with touchscreens by providing simulated tactile feedback, and can be designed to react immediately, partly
`countering on-screen response latency. Research from the University of Glasgow Scotland [Brewster, Chohan, and
`Brown 2007 and more recently Hogan] demonstrates that sample users reduce input errors (20%), increase input
`speed (20%), and lower their cognitive load (40%) when touchscreens are combined with haptics or tactile feedback
`[vs. non-haptic touchscreens].
`
`"Gorilla arm"
`
`Extended use of gestural interfaces without the ability of the user to rest their arm is referred to as "gorilla arm."[47]
`It can result in fatigue, and even repetitive stress injury when routinely used in a work setting. Certain early pen-
`based interfaces required the operator to work in this position for much of the work day.[48] Allowing the user to rest
`their hand or arm on the input device or a frame around it is a solution for this in many contexts. This phenomenon
`is often cited as a prima facie example of what not to do in ergonomics.
`
`Unsupported touchscreens are still fairly common in applications such as ATMs and data kiosks, but are not an
`issue as the typical user only engages for brief and widely spaced periods.[49]
`
`Fingerprints
`
`Touchscreens can suffer from the problem of fingerprints on the display. This can be mitigated by the use of
`materials with optical coatings designed to reduce the visible effects of fingerprint oils, or oleophobic coatings as
`most of the modern smartphones, which lessen the actual amount of oil residue, or by installing a matte-finish anti-
`glare screen protector, which creates a slightly roughened surface that does not easily retain smudges, or by
`reducing skin contact by using a fingernail or stylus.
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`See also
`◾ Dual-touchscreen
`◾ Pen computing
`◾ Energy harvesting
`◾ Flexible keyboard
`◾ Gestural interface
`◾ Graphics tablet
`◾ Graphics tablet-screen hybrid
`◾ Lock screen
`◾ List of Touch Solution manufacturers
`◾ Tablet PC
`◾ Touch switch
`◾ Touchscreen remote control
`◾ Multi-touch
`◾ Omnitouch
`◾ SixthSense
`Notes
`
`Fingerprints and smudges on an iPad
`touchscreen
`
`1. Walker, Geoff (August 2012). "A review of technologies for sensing contact location on the surface of a
`display" (http://onlinelibrary.wiley.com/doi/10.1002/jsid.100/abstract). Journal of the Society for Information Display 20
`(8): 413–440. doi:10.1002/jsid.100 (https://dx.doi.org/10.1002%2Fjsid.100).
`2. "The first capacitative touch screens at CERN" (http://cerncourier.com/cws/article/cern/42092). CERN Courrier. 31
`March 2010. Retrieved 2010-05-25
`3. Bent STUMPE (16 March 1977). "A new principle for x-y touch
`system" (http://cdsweb.cern.ch/record/1266588/files/StumpeMar77.pdf) (PDF). CERN. Retrieved 2010-05-25
`4. Bent STUMPE (6 February 1978). "Experiments to find a manufacturing process for an x-y touch
`screen" (http://cdsweb.cern.ch/record/1266589/files/StumpeFeb78.pdf) (PDF). CERN. Retrieved 2010-05-25
`5. Frank BECK & Bent STUMPE (24 May 1973). "Two devices for operator interaction in the central control of the new
`CERN accelerator" (http://cdsweb.cern.ch/record/186242/files/p1.pdf) (PDF). CERN. Retrieved 2010-05-25
`6. Johnson, E.A. (1965). "Touch Display - A novel input/output device for computers". Electronics Letters 1 (8): 219–220.
`doi:10.1049/el:19650200 (https://dx.doi.org/10.10