touchscreen for the hewlettpackard computer see hp touchscreen touch sensitive redirects here for other uses see touch sensitive a touchscreen or touch screen is an input device and 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 multitouch gestures by touching the screen with a special stylus or one or more fingers some touchscreens use ordinary or specially coated gloves to work while others may only work using a special stylus or pen the user can use the touchscreen to react to what is displayed and if the software allows to control how it is displayed for example zooming to increase the text size the touchscreen enables the user to interact directly with what is displayed rather than using a mouse touchpad or other such devices other than a stylus which is optional for most modern touchscreens touchscreens are common in devices such as game consoles personal computers electronic voting machines and pointofsale pos systems they can also be attached to computers or as terminals to networks they play a prominent role in the design of digital appliances such as personal digital assistants pdas and some ereaders 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 heavy industry 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 displays content historically the touchscreen sensor and its accompanying controllerbased firmware have been made available by a wide array of aftermarket system integrators and not by display chip or motherboard manufacturers display manufacturers and chip manufacturers have acknowledged the trend toward acceptance of touchscreens as a user interface component and have begun to integrate touchscreens into the fundamental design of their products history the prototype in 1972 eric johnson of the royal radar establishment located in malvern england described his work on capacitive touchscreens in a short article published in 1965 in 1972 a group at the university of illinois filed for a patent on an optical touchscreen hp mounted their infrared transmitters and receivers around the bezel of a 9inch sony cathode ray tube crt in 1984 fujitsu released a touch pad for the micro 16 to accommodate the complexity of kanji characters which were stored as tiled graphics touchsensitive controldisplay units cdus were evaluated for commercial aircraft flight decks in the early 1980s initial research showed that a touch interface would reduce pilot workload as the crew could then select waypoints functions and actions rather than be head down typing latitudes longitudes and waypoint codes on a keyboard an effective integration of this technology was aimed at helping flight crews maintain a highlevel of situational awareness of all major aspects of the vehicle operations including the flight path the functioning of various aircraft systems and momenttomoment human interactions in the early 1980s general motors tasked its delco electronics division with a project aimed at replacing an automobiles nonessential functions ie other than throttle transmission braking and steering from mechanical or electromechanical 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 multitouch technology began in 1982 when the university of torontos input research group developed the first humaninput multitouch system using a frostedglass panel with a camera placed behind the glass in 1985 the university of toronto group including bill buxton developed a multitouch tablet that used capacitance rather than bulky camerabased optical sensing systems see multitouchhistory of multitouch the first commercially available graphical pointofsale pos software was demonstrated on the 16bit atari 520st color computer it featured a color touchscreen widgetdriven interface in 1987 casio launched the casio pb1000 pocket computer with a touchscreen consisting of a 44 matrix resulting in 16 touch areas in its small lcd graphic screen touchscreens had the bad reputation of being imprecise until 1988 most userinterface books would state that touchscreen selections were limited to targets larger than the average finger at the time selections were done in such a way that a target was selected as soon as the finger came over it and the corresponding action was performed immediately errors were common due to parallax or calibration problems leading to user frustration liftoff strategy was introduced by researchers at the university of maryland humancomputer interaction lab hcil as users touch the screen feedback is provided as to what will be selected users can adjust the position of the finger and the action takes place only when the finger is lifted off the screen this allowed the selection of small targets down to a single pixel on a 640480 video graphics array vga screen a standard of that time sears et al 1990 gave a review of academic research on single and multitouch humancomputer interaction of the time describing gestures such as rotating knobs adjusting sliders and swiping the screen to activate a switch or a ushaped gesture for a toggle switch the hcil team developed and studied small touchscreen keyboards including a study that showed users could type at 25 wpm on a touchscreen keyboard aiding their introduction on mobile devices they also designed and implemented multitouch gestures such as selecting a range of a line connecting objects and a tapclick gesture to select while maintaining location with another finger in 1990 hcil demonstrated a touchscreen slider in 19911992 the sun star7 prototype pda implemented a touchscreen with inertial scrolling in 1993 ibm released the ibm simon the first touchscreen phone an early attempt at a handheld game console with touchscreen controls was segas 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 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 multitouch technology technologies there are a variety of touchscreen technologies with different methods of sensing touch resistive resistive touchscreen a resistive touchscreen panel comprises several thin layers the most important of which are two transparent electrically resistive layers facing each other with a thin gap between the top layer that which is touched has a coating on the underside surface 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 pressure on the screen can be determined resistive touch is used in restaurants factories and hospitals due to its high tolerance for liquids and contaminants a major benefit of resistivetouch 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 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 ie glare from the layers of material placed over the screen surface acoustic wave surface acoustic wave surface acoustic wave saw technology uses ultrasonic waves that pass over the touchscreen panel when the panel is touched a portion of the wave is absorbed the change in ultrasonic waves is processed by the controller to determine the position of the touch event 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 capacitive touchscreen of a mobile phone capacitive sensing a capacitive touchscreen panel consists of an insulator such as glass coated with a transparent conductor such as indium tin oxide ito as the human body is also an electrical conductor touching the surface of the screen results in a distortion of the screens 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 specialapplication glove with an embroidered patch of conductive thread allowing electrical contact with the users fingertip leading capacitive display manufacturers continue to develop thinner and more accurate touchscreens those for mobile devices are now being produced with incell technology such as in samsungs super amoled screens that eliminates a layer by building the capacitors inside the display itself this type of touchscreen reduces the visible distance between the users finger and what the user is touching on the screen creating a moredirect contact with the image of displayed content and enabling taps and gestures to be more responsive a simple parallelplate 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 parallelplate 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 or cf the capacitance of the sensor without a finger present is known as parasitic capacitance or cp 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 sensors 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 projected capacitance back side of a multitouch globe based on projected capacitive touch pct technology 8 x 8 projected capacitance touchscreen manufactured using 25 micron insulation coated copper wire embedded in a clear polyester film schema of projectedcapacitive touchscreen projected capacitive touch pct also pcap technology is a variant of capacitive touch technology this technology was first developed by ronald and malcolm binstead in 1984 when a simple 16 key capacitive touchpad was invented accurate sensing was achieved due to 1 the slow but continuous updating of the notouch reference value for each key eliminating medium to long term problems associated with dirt and ageing 2 the change in value for each key being compared with the relative change in value for each of the other keys to see if the pattern of change corresponded to the change that would be expected to be caused by a nearby finger as opposed to localised heating rain or other environmental factors in 1989 the 16 discrete copper foil keys of the keypad were replaced with 16 transparent indium tin oxide keys creating a clear keypad touch screen that could sense through thick glass a simple to manufacture multiple input xy multiplexed version of this touch screen was invented in 1994 this could use indium tin oxide or 10 to 25 micron diameter insulation coated copper wires as the sensing elements the first version enabled 64 touch positions to be detected with just 16 inputs see image on the right due to their low cost and ability to survive in hostile environments 7000 of these were used by jpm international in their monopoly pub gaming machines in 1997 much higher touch resolution was enabled by the introduction of more 16 16 inputs and interpolating between the 256 touch positions where these sensing elements intersected in 1999 the ability of this technology to sense through thick nonconductive materials was publicly termed projective capacitive for the first time later this term was modified by zytronic displays to projected capacitance some modern pct touch screens are composed of thousands of discrete keys but most pct touch screens are made 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 in some designs 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 this system is able to accurately track touches due to the top layer of a pct being glass it is sturdier than lessexpensive resistive touch technology unlike traditional capacitive touch technology it is possible for a pct system to sense a passive stylus or gloved finger however moisture on the surface of the panel high humidity or collected dust can interfere with performance these environmental factors however are not a problem with fine wire based touchscreens due to the fact that wire based touchscreens have a much lower parasitic capacitance and there is greater distance between neighbouring conductors there are two types of pct mutual capacitance and selfcapacitance 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 1614 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 of the sensor changes the local electrostatic field which in turn 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 multitouch operation where multiple fingers palms or styli can be accurately tracked at the same time selfcapacitance selfcapacitance sensors can have the same xy grid as mutual capacitance sensors but the columns and rows operate independently with selfcapacitance the capacitive load of a finger is measured on each column or row electrode by a current meter or the change in frequency of an rc oscillator which allows some parts of a capacitance sensor to be sensitive to touch while other parts are insensitivethe patent author discovered that a self capacitance sensing conductor x in an xy array of conductors cannot detect the close proximity of a finger if the x conductor is crossed by a conductor y whose waveform is 180 degrees out of phase with its own sensing waveform this makes it possible to mask off ambiguous possible ghost intersections to confirm if a finger is close to that intersection or not for the first time this enabled self capacitance to be used for multitouch without ghosting use of styli on capacitive screens capacitive touchscreens do not necessarily need to be operated by a finger but until recently the special styli required could be quite expensive to purchase the cost of this technology has fallen greatly in recent years and capacitive styli are now widely available for a nominal charge and often given away free with mobile accessoriesthese consist of an electrically conductive shaft with a soft conductive rubber tip thereby resistively connecting the fingers to the tip of the stylus infrared grid infrared sensors mounted around the display watch for a users touchscreen input on this plato v terminal in 1981 the monochromatic plasma displays characteristic orange glow is illustrated an infrared touchscreen uses an array of xy 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 opaque object including a finger gloved finger stylus or pen it is generally used in outdoor applications and pos systems which cannot 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 and dust that can interfere with the infrared beams and suffer from parallax in curved surfaces and accidental press when the user hovers a finger over the screen while searching for the item to be selected infrared acrylic projection a translucent acrylic sheet is used as a rearprojection 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 users touch location microsofts pixelsense tablets use this technology optical imaging 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 backlights are placed in the cameras field of view on the opposite side of the screen a touch blocks some lights from the cameras and the location and size of the touching object can be calculated see visual hull this technology is growing in popularity due to its scalability versatility and affordability for larger touchscreens dispersive signal technology introduced in 2002 by 3m this system detects a touch by using sensors to measure the piezoelectricity in the glass complex algorithms interpret this information and provide the actual location of the touch the technology is 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 any object can be used to generate touch events including gloved fingers a downside is that after the initial touch the system cannot detect a motionless finger however for the same reason resting objects do not disrupt touch recognition 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 signal as measured by three or more tiny transducers attached to the edges of the touchscreen the digitized signal is compared to a list corresponding to every position on the surface determining 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 soundbased technologies by using a simple lookup method rather than expensive signalprocessing hardware 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 internationals elo division in 2006 as acoustic pulse recognition the touchscreen used by elo is made of ordinary glass giving good durability and optical clarity the technology usually retains accuracy with scratches and dust on the screen the technology is also well suited to displays that are physically larger construction this section needs expansion you can help by adding to it september 2017 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 capacitive resistive approach the most popular technique there are typically four layers top polyestercoated layer with a transparent metallicconductive coating on the bottom adhesive spacer this diagram shows how eight inputs to a lattice touchscreen or keypad creates 28 unique intersections as opposed to 16 intersections created using a standard xy multiplexed touchscreen glass layer coated with a transparent metallicconductive coating on the top 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 dispersivesignal technology measures the piezoelectric effectthe voltage generated when mechanical force is applied to a materialthat occurs chemically when a strengthened glass substrate is touched there are two infraredbased approaches in one an array of sensors detects a finger touching or almost touching the display thereby interrupting infrared light beams projected over the screen in the other bottommounted infrared cameras record heat from screen touches in 1995 binstead designs patented a very simple to manufacture multiple input fine wire based touchscreen the xy layout commonly used in touchscreens has also been improved by using a diagonal lattice layout where there are no dedicated x or y elements but each element may be transmitting or sensing at different times during a scan of the touchscreen this means that there are nearly twice as many crossover points for a fixed number of terminal connections and no bussed connections around the edges of the touchscreen 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 cost of touchscreen technology is routinely absorbed into the products that incorporate it and is nearly eliminated touchscreen technology has demonstrated reliability and is found in airplanes automobiles gaming consoles machine control systems appliances and handheld display devices including cellphones the touchscreen market for mobile devices was projected to produce us5 billion by 2009 the ability to accurately point on the screen itself is also advancing with the emerging graphics tabletscreen hybrids polyvinylidene fluoride pvfd plays a major role in this innovation due its high piezoelectric properties 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 etc ergonomics and usage touchscreen accuracy for touchscreens to be effective input devices users must be able to accurately select targets and avoid accidental selection of adjacent targets the design of touchscreen interfaces should reflect 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 typically using infrared gridswhich were highly dependent on the size of the users fingers these guidelines are less relevant for the bulk of modern devices which use capacitive or resistive touch technology from the mid2000s 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 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 least accurate at the top edge and especially the bottom edge the r95 accuracy required radius for 95 target accuracy varies from 7mm 028in in the center to 12mm 047in in the lower corners this user 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 providedsuch as onscreen magnifiersusers can move their finger once in contact with the screen with precision as small as 01mm 0004in 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 holding at least in part with both hands tapping with a single thumb holding with two hands and tapping with both thumbs holding with one hand tapping with the finger or rarely thumb of another hand holding the device in one hand and tapping with the thumb from that same hand use rates vary widely while twothumb tapping is encountered rarely 13 for many general interactions it is used for 41 of typing interaction 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 vary use of these methods 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 users experience with touchscreens by providing simulated tactile feedback and can be designed to react immediately partly countering onscreen response latency research from the university of glasgow brewster chohan and brown 2007 and more recently hogan demonstrates that touchscreen users reduce input errors by 20 increase input speed by 20 and lower their cognitive load by 40 when touchscreens are combined with haptics or tactile feedback gorilla arm extended use of gestural interfaces without the ability of the user to rest their arm is referred to as gorilla arm 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 fingerprints fingerprints and smudges on a ipad tablet computer touchscreen 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 most modern smartphones have oleophobic coatings which lessen the amount of oil residue another option is to install a mattefinish antiglare screen protector which creates a slightly roughened surface that does not easily retain smudges dualtouchscreen pen computing energy harvesting flexible keyboard gestural interface graphics tablet light pen list of touchsolution manufacturers lock screen tablet computer touch switch touchscreen remote control multitouch omnitouch sixthsense nintendo ds notes mwparseroutput refbeginfontsize90marginbottom05emmwparseroutput refbeginhangingindentsulliststyletypenonemarginleft0mwparseroutput refbeginhangingindentsullimwparseroutput refbeginhangingindentsdlddmarginleft0paddingleft32emtextindent32emliststylenonemwparseroutput refbegin100fontsize100 shneiderman b 1991 touch screens now offer compelling uses ieee software 8 2 9394 107 doi1011095273754 potter r weldon l shneiderman b 1988 an experimental evaluation of three strategies proc chi88 washington dc acm press pp2732 sears a plaisant c shneiderman b 1992 a new era for high precision touchscreens in hartson r hix d advances in humancomputer interaction 3 ablex nj pp133 sears a shneiderman b 1991 high precision touchscreen design strategies and comparison with a mouse international journal of manmachine studies 34 4 593613 doi1010160020737391900378 holzinger a 2003 finger instead of mouse touch screens as a means of enhancing universal access in carbonell n stephanidis c eds universal access lecture notes in computer science lecture notes in computer science 2615 387397 doi101007354036572930 isbn9783540008552 wikimedia commons has media related to touchscreens look up touch screen in wiktionary the free dictionary howstuffworks how do touchscreen monitors know where youre touching how does touch screen work what are the different types of touchscreen technology from touch displays to the surface a brief history of touchscreen technology annotated bibliography of references to touchscreens gestures and pen computing part 1 fundamentals of projectedcapacitive touch technology geoff walker june 2014 notes on the history of penbased computing on youtube vtebasic computer componentsinput devices keyboard image scanner microphone pointing device graphics tablet joystick light pen mouse optical pointing stick touchpad touchscreen trackball refreshable braille display sound card webcam softcam video card output devices monitor refreshable braille display printer speakers plotter sound card video card removable data storage optical disc cd dvd bluray disk pack floppy disk memory card usb flash drive computer case central processing unit cpu hdd ssd sshd motherboard network interface controller power supply randomaccess memory ram fax modem expansion card ports ethernet firewire ieee 1394 parallel port serial port ps2 port usb thunderbolt displayport hdmi dvi vga esata audio jack authority control gnd 46745853 ndl 01163599 