The touch screen screen is an input and output device typically coated on the top of the electronic visual display of an information processing system. Users can provide input or control information processing systems through simple or multi-touch gestures by touching the screen with a special stylus or one or more fingers. Some touch screens use regular or coated gloves to work while others may only work with a special stylus or pen. Users can use the touch screen to react to what is displayed and, if the software allows, to control how it looks; for example, zoom in to increase the text size.
The touch screen allows the user to interact directly with what is displayed, rather than using a mouse, touchpad, or other device like that (other than the stylus, which is optional for most modern touch screens).
The touch screen is often found on devices such as game consoles, personal computers, electronic voting machines, and point-of-sale (POS) systems. They can also be attached to the computer or, as a terminal, to the network. They play an important role in the design of digital equipment such as personal digital assistants (PDAs) and some e-readers.
The popularity of smartphones, tablets, and various types of information equipment drives the demand and acceptance of a common touch screen for portable and functional electronics. Touch screens are found in the medical, heavy industry, automated teller machines (ATMs), and kiosks such as museum displays or room automation, where the keyboard and mouse systems do not permit the user's intuitive, fast, or accurate interaction with display content.
Historically, the touchscreen sensor and its accompanying controller-based firmware are available by a variety of after-market system integrators, and not by display, chip or motherboard manufacturers. Screen manufacturers and chip manufacturers have recognized the trend towards receiving touchscreens as a component of the user interface and have begun integrating touchscreens into their fundamental product designs.
Video Touchscreen
Histori
Eric Johnson, of Royal Radar Establishment, located in Malvern, England, described his work on capacitive touch screens in a short article published in 1965 and then more fully - with photographs and diagrams - in an article published in 1967. Application of technology touch for air traffic control described in an article published in 1968. Frank Beck and Bent Stumpe, engineers from CERN (European Organization for Nuclear Research), developed a transparent touch screen in the early 1970s, based on Stumble's work in a television factory in early 1960s. Later manufactured by CERN, it was used in 1973. A resistive touch screen was developed by American inventor George Samuel Hurst, who received the US patent No. Ã, 3,911,215 on October 7, 1975 The first version was produced in 1982.
In 1972, a group at the University of Illinois filed a patent on an optical touch screen that became a standard part of the Magnavox Plato IV Student Terminal and thousands built for this purpose. These touchscreens have an array of 16-16 infrared position sensors, each consisting of LEDs on one side of the screen and a matching phototransistor on the other, all mounted in front of monochrome plasma display panels. This arrangement can feel a faded object fingertip-sized near the screen. Similar touch screens were used on the HP-150 starting in 1983. The HP 150 is one of the earliest commercial touch screen computers in the world. HP installs their infrared transmitter and receiver around Sony 9-inch (CRT) cathode ray tube bezel.
In 1984, Fujitsu released a touch pad for Micro 16 to accommodate the complexity of kanji characters, which are stored as charts. In 1985, Sega released Terebi Oekaki, also known as Sega Graphic Board, for the SG-1000 video game console and SC-3000 home computer. It consists of a plastic pen and a plastic board with a transparent window where pen compression is detected. It is used primarily with drawing software applications. Graphical touch tablets were released for Sega AI computers in 1986.
Touch sensitive touch screen units (CDUs) were evaluated for the deck of commercial aircraft flight in the early 1980s. Initial research indicates that the touch interface will reduce the pilot's workload as a crew and then can choose waypoints, functions and actions, rather than being "lower head" typing latitude, longitude, and waypoint codes on the keyboard. The effective integration of this technology aims to help flight crews maintain high-level situational awareness of all major aspects of vehicle operation including flight paths, various aircraft system functions, and moment-to-moment human interaction.
In the early 1980s, General Motors commissioned the Delco Electronics division with projects aimed at replacing non-essential car functions (ie in addition to throttle, transmission, braking and steering) of mechanical or electro-mechanical systems with solid state alternatives wherever possible. The so-called ECC devices for "Electronic Control Center", digital computers and software control systems are connected to a variety of peripheral sensors, servo, solenoid, antenna, and monochrome CRT touchscreens that function both as a single display and input method. ECC replaces traditional mechanical stereos, fans, heaters and controls and air-conditioning displays, and is able to provide very detailed and specific information about the vehicle's cumulative current and operating status in real time. ECC was standard equipment in 1985-1989 Buick Riviera and later Buick Reatta 1988-1989, but was not popular among consumers - partly due to the technophobia of some traditional Buick customers, but largely due to the expensive technical issues suffered by ECC touch screens that would make climate control or stereo operation is impossible.
The multi-touch technology began in 1982, when the Input Research Group of the University of Toronto developed the first multi-touch human input system, using a frosted glass panel with a camera placed behind glass. In 1985, the University of Toronto group, including Bill Buxton, developed a multi-touch tablet that uses capacitance rather than a large camera-based optical sensing system (see Multi-touch # History multi-touch).
The commercially available commercially available point-of-sale (POS) software is shown on a 16-bit Atari 520ST color computer. It features a widget-driven color touchscreen interface. ViewTouch POS software was first demonstrated by its developer, Gene Mosher, at Atari Computer's demonstration area at the Fall COMDEX show in 1986.
In 1987, Casio launched the Casio PB-1000 pocket computer with a touch screen consisting of a 4 × 4 matrix, producing 16 touch fields in a small LCD graphic display.
Touchscreens had an improper bad reputation until 1988. Most user interface books would state that touch screen options are limited to targets larger than the average finger. At that point, the choice is done in such a way that the target is selected as soon as the finger passes through it, and appropriate action is taken immediately. Common errors occur, due to parallax or calibration issues, leading to user frustration. "Lift strategy" was introduced by researchers at the University of Maryland's Human-Computer Interaction Laboratory (HCIL). When the user touches the screen, the feedback is given as to what will be selected: the user can adjust the finger position, and the action only occurs when the finger is lifted off the screen. This allows the selection of small targets, down to one pixel on the 640 Video Graphics Array (VGA) screen (the standard of the time).
Sears et al. (1990) provides a review of academic research on single-person and multi-touch human-time interactions, describing movements such as turning the knob, adjusting the slider, and swiping the screen to activate the switch (or U-shaped movement to switch switch). The HCIL team developed and studied small touchscreen keyboards (including research that shows users can type at 25 wpm on the touchscreen keyboard), helping them to recognize on mobile devices. They also design and apply multi-touch gestures such as selecting different lines, connecting objects, and "tap-click" movements to choose while maintaining locations with other fingers.
In 1990, HCIL demonstrated a touchscreen slider, later referred to as the previous work in key-screen patent litigation between Apple and other touch screen mobile vendors (linked to U.S. Patent 7,657,849 ).
In 1991-1992, Sun Star7's PDA prototype implemented a touch screen with inertial scroll. In 1993, IBM released IBM's first Simon touch-screen phone.
Early attempts at handheld gaming consoles with touchscreen controls were Sega's successors meant for Game Gear, although the device was eventually shelved and never released due to the high price of touch-screen technology in the early 1990s.
The invention of new touch-screen technology in 1994, which is cheap and weatherproofing, allows touch screens to be used in pub gaming machines for the first time, the first application to be in the JPM Monopoly game.
Touchscreens will not be popular used for video games until the launch of the Nintendo DS in 2004. To date, most consumer touch screens can only feel a single point of contact at a time, and some have the ability to sense how hard it is to touch. This has changed with the commercialization of multi-touch technology.
Maps Touchscreen
Technology
There are various touch screen technology with various methods of touch sensing.
Resistive
Resistive touchscreen panel consists of several thin layers, the most important are two transparent electrically resistive layers facing each other with a thin gap between the two. The top layer (touched) has a layer on the bottom surface; just below it is a similar resistive layer on its substrate. One layer has a conductive connection along its sides, the other along the top and bottom. Voltage applied to one layer, and felt by others. When an object, such as the fingertip or the tip of the stylus, presses to the outer surface, the two layers touch to be connected at that point. The panel then behaves as a pair of voltage dividers, one axis at a time. By moving between layers quickly, the pressure position on the screen can be determined.
Resistive touches are used in restaurants, factories and hospitals because of their high tolerance of fluids and contaminants. The main benefit of resistive touch technology is its low cost. In addition, since only enough pressure is required for the touch to be felt, they can be used with gloves, or by using something rigid instead of a finger. Disadvantages include the need to suppress, and the risk of damage by sharp objects. Resistive touch screens also experience a worse contrast, because it has additional reflections (ie glare) from the material layer placed above the screen. This is the type of touch screen used by Nintendo in the DS family, the 3DS family, and the Wii U GamePad.
Surface acoustic waves
Surface acoustic wave (SAW) technology uses ultrasonic waves that pass through the touchscreen panel. When the panel is touched, a portion of the wave is absorbed. Changes in ultrasonic waves are processed by the controller to determine the position of the touch event. The surface acoustic wave touchscreen panel can be damaged by external elements. Contaminants on the surface can also interfere with touch screen functionality.
Capacitive
The capacitive touch screen panel consists of insulators, such as glass, coated with transparent conductors, such as indium tin oxide (ITO). Since the human body is also an electrical conductor, touching the surface of the screen produces a distortion of the electrostatic field of the screen, which can be measured as a change in capacitance. Different technologies can be used to determine the location of the touch. The location is then sent to the controller for processing.
Unlike resistive touch screens, one can not use capacitive touch screens through most types of electrical insulating materials, such as gloves. These losses mainly affect usability in consumer electronics, such as touch tablet PCs and capacitive smart phones in cold weather. This can be overcome with a special capacitive stylus, or a special application glove with a conductive thread embroidery patch that allows electrical contact with the user's fingertips.
Leading capacitive display manufacturers continue to develop thinner and more accurate touchscreen. Those for mobile devices are now manufactured with 'in-cell' technology, like in Samsung's Super AMOLED screen, which removes layers by building capacitors inside the screen itself. This type of touch screen reduces the visible distance between the user's finger and what the user touches on the screen, creates more direct contact with the displayed content image and allows taps and movements to become more responsive.
Simple parallel-plate capacitors have two conductors separated by a dielectric layer. Most of the energy in this system is concentrated directly between the plates. Some energy spills into the area outside the plate, and the electric field line associated with this effect is called the fringing field. Part of the challenge of making capacitive sensitive sensors is to design a set of printed circuitry traces that direct the fringing plane to the user-accessible sensing area. Parallel capacitors are not a good choice for such sensor patterns. Placing a finger near the fringing electric field increases the area of ​​the conductive surface to the capacitive system. The additional charge storage capacity added by the finger is known as the finger capacitance, or CF. The capacitance of the sensor without the presence of a finger is known as the 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, producing a uniform electrostatic field. When a conductor, like a human finger, touches an uncoated surface, the capacitor is dynamically formed. The sensor controller can determine the location of the touch indirectly from the measured capacitance changes of the four corners of the panel. Because it has no moving parts, it is durable enough but has limited resolution, prone to false signals from parasitic capacitive coupling, and requires calibration during manufacture. It is therefore most commonly used in simple applications such as industrial controls and kiosks.
Capacitance projection
The capacitive touch (PCT; also PCAP) technology is projected to be a variant of capacitive touch technology.
This technology was first developed in 1984 when a simple 16-key capacitive touchpad was found that can feel the finger through a very thick glass, although the signal to be felt is significantly smaller than the change in capacitance caused by various environmental factors such as moisture, dirt, rain and temperature.
Accurate sensing is achieved because:
1) a slow but continuous update of "touchless" reference values ​​for each key, eliminating medium and long term problems associated with dirt and aging.
2) change the value for each key compared to the relative value change for each of the other keys, to see if the change pattern corresponds to the change that would be expected to be caused by a nearby finger, as opposed to local heating, rain, or other environmental factors.
In 1989, 16 pieces of copper keys from the keypad were replaced with 16 transparent Indium Tin Oxide buttons, creating a clear keypad/touch screen that can be felt through the thick glass..
A simplified version for producing x/y multiplexes from the touch screen was discovered in 1994. The first version allows 64 touch positions to be detected with just 16 inputs.
Due to the low cost and ability to survive in a hostile environment, 7000 of these are used by JPM in their 'Monopoly' pub game machine.
In 1999, the ability of this technology to sense through a thick non-conductive material is called 'Projection Capacitive' for the first time.
Then the term is modified by Zytronic Displays into 'Projection Capacitance'.
Some modern PCT touch screens consist of thousands of discrete keys, but most of the PCT touch screen is made of a matrix of rows and columns of conductive materials, laminated on glass sheets.
This can be done either by etching a single conductive layer to form a grid pattern of the electrode, or by etching two separate, perpendicular layers of conductive material with lines or parallel tracks to form the grid.
In some designs, the voltage applied to the grid creates a uniform electrostatic field, which can be measured. When a conductive object, such as a finger, is in contact with a PCT panel, it distorts the local electrostatic field at that point. This can be measured as a change in capacitance. If the finger bridges the gap between the two "tracks", the charge field becomes more disturbed and detected by the controller. Capacitance can be changed and measured at every point on the grid. The system is able to track the touch accurately.
Since the top layer of PCT is glass, it is stronger than the cheaper resistive touch technology. Unlike traditional capacitive touch technology, it is possible for PCT systems to sense passive stylus or gloved fingers. However, moisture on the panel surface, high humidity, or dust collected may interfere with performance.
This environmental factor, however, does not matter with touchscreens based on 'fine wire' due to the fact that wire-based touchscreens have much lower 'parasitic' capacitances, and there is a greater distance between neighboring conductors.
There are two types of PCT: mutual capacitance and self capacitance.
Shared capabilities
This is a general PCT approach, which utilizes the fact that most conductive objects can withstand a charge if they are so close together. In a capacitive sensor together, a capacitor is inherently formed by a row trace and a trace column at each grid intersection. A 16 Ã- 14 array, for example, will have 224 independent capacitors. Voltage applied to rows or columns. Carrying a finger or a conductive stylus near the sensor surface will change the local electrostatic field, which in turn reduces the reciprocal capacitance. The change in capacitance at each individual point on the grid can be measured to accurately determine the location of the touch by measuring the voltage across the other axis. Mutual capacitance allows multi-touch operation where multiple fingers, palms or needles can be tracked accurately at the same time.
Self-Capacity
The self-capacitance sensor can have the same X-Y grid as the capacitance sensor together, 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, or a frequency change of an RC oscillator. This method produces a stronger signal than the shared capacitance, but can not accurately complete more than one finger, resulting in "ghosting" or misplaced location sensing. However, in 2010 a new method of patented sensing that allows some parts of the capacitance sensor to be sensitive to touch while other parts remain insensitive. This allows Self capacitance to be used for multi-touch without "ghosting".
Use styli on capacitive screen
The capacitive touch screen does not need to be operated by fingers, but to date, the special styli required can be very expensive to buy. The cost of this technology has greatly decreased in recent years and capacitive styli is now widely available at a nominal cost, and is often provided for free with mobile phone accessories. It consists of a conductive electric shaft with a soft conductive rubber end.
Infrared grid
The infrared touch screen uses an X-Y infrared LED array and a photodetector pair around the edges of the screen to detect interference in LED light patterns. These LED beams intersect in vertical and horizontal patterns. This helps the sensor take the exact location of the touch. The main benefit of such a system is that it can detect essentially any frosted object including the finger, gloved finger, stylus or pen. These are commonly used in outdoor applications and POS systems that can not rely on conductors (such as bare fingers) to enable touch screens. Unlike capacitive touch screens, the infrared touch screen requires no pattern on the glass that improves the overall optical endurance and clarity of the system. Infrared touchscreens are sensitive to dirt and dust that can interfere with infrared light, and suffer parallax in curved surfaces and unintentional presses when the user places his finger on the screen while searching for the item to be selected.
Infrared acrylic projection
Translucent acrylic sheets are used as rear projection screen to display information. The edges of acrylic sheets are illuminated by infrared LEDs, and infrared cameras are focused on the back of the sheet. The objects placed on the sheet can be detected by the camera. When the sheet is touched by the user, the deformation produces an infrared light leak that culminates at the maximum pressure points, indicating the location of the user's touch. Microsoft PixelSense Tablet uses this technology.
Optical imagery
The optical touch screen is a relatively modern development in touch screen technology, where two or more image sensors are placed around the edge (most corners) of the screen. Infrared backlight is placed in the camera field of view on the opposite side of the screen. The touch blocks some light from the camera, and the location and size of the touching object can be counted (see visual hull). This technology is increasingly popular because of its scalability, versatility, and affordability for larger touch screens.
Dispensive signal technology
Introduced in 2002 by 3M, the system detects touch by using sensors to measure piezoelectricity on the glass. The complex algorithm interprets this information and gives the actual location of the touch. This technology is not affected by dust and other outer elements, including scratches. Since there is no need for additional elements on the screen, it also claims to provide excellent optical clarity. Each object can be used to generate touch events, including gloved fingers. The downside is that after the initial touch, the system can not detect a finger that does not move. However, for the same reason, resting objects do not interfere with touch recognition.
Introduction of acoustic pulses
The key to this technology is that a touch on one of the positions on the surface produces sound waves on the substrate which then generates a unique combined signal measured by three or more small transducers attached to the edge of the touch screen. The digital signal is compared to the list corresponding to each position on the surface, determining the location of the touch. The moving touch is tracked by a rapid repetition of this process. External and ambient sounds are ignored because they do not match the stored sound profile. This technology differs from other voice-based technologies by using simple search methods rather than expensive signal processing devices. Like a dispersive signal technology system, a fixed finger can not be detected after the initial touch. However, for the same reason, the introduction of touch is not disturbed by the resting object. This technology was invented by SoundTouch Ltd. in the early 2000s, as described by the patent family EP1852772, and was introduced to the market by the Elo Tyco International division in 2006 as Acoustic Pulse Recognition. The touch screen used by Elo is made of ordinary glass, providing excellent resistance and optical clarity. This technology usually maintains accuracy with scratches and dust on the screen. This technology is also suitable for physically larger displays.
Construction
There are several main ways to build a touch screen. The main purpose is to recognize one or more fingers touching the screen, to interpret the commands it represents, and to communicate commands to the appropriate application.
In a capacitive resistive approach, the most popular technique, there are usually four layers:
- The top polyester-coated layer with a transparent metal-conductive layer at the bottom.
- The spacer adhesive
- The glass coating is coated with a transparent metal-conductive layer at the top
- Adhesive coating on the back of the glass for installation.
When a user touches a surface, the system records changes in the electrical current flowing through the screen.
The dispersive signal technology measures the piezoelectric effect - the voltage generated when a mechanical force is applied to a chemically-occurring material when a reinforced glass substrate is touched.
There are two approaches based on infrared. In one, the sensor array detects the touch of a finger or almost touches the screen, thus interfering with the infrared light projected above the screen. On the other hand, infrared cameras mounted on the bottom record heat from the touch screen.
In 1995, Binstead Design patented a very simple wire-based touch screen.
The x/y layout has also been enhanced by using the grid layout, where there are no special elements x or y, but each element can transmit or sense at different times during touch screen scanning. This means that there are almost twice as many cross-over points for a fixed number of terminal connections.
In each case, the system determines the intended command based on the control displayed on the screen at that moment and the touch location.
Development
The development of multipoint touchscreen facilitates the tracking of more than one finger on the screen; thus, operations requiring more than one finger are possible. This device also allows many users to interact with the touch screen simultaneously.
With the increasing use of touch screens, the cost of touch screen technology is routinely absorbed into products that combine and almost eliminated. Touch screen technology has demonstrated reliability and is found in aircraft, cars, game consoles, machine control systems, equipment, and handheld display devices including mobile phones; the touch screen market for mobile devices is projected to generate US $ 5 billion in 2009.
The ability to accurately point to the screen itself also advances with hybrid graphics display tablets that appear. Polyvinylidene fluoride (PVFD) plays a major role in this innovation because of its high piezoelectric properties.
TapSense, announced in October 2011, allows touch screens to distinguish which parts of hands are used for input, such as fingertips, knuckles and fingernails. It can be used in various ways, for example, to copy and paste, to take advantage of letters, to enable different image modes, etc.
Ergonomics and usage
Touchscreen accuracy
For the touch screen to be an effective input device, the user must be able to accurately select the target and avoid accidentally selecting adjacent targets. The design of the touch screen interface should reflect the system's technical capabilities, ergonomics, cognitive psychology, and human physiology.
The guidelines for touch-screen design were first developed in the 1990s, based on preliminary research and actual use of old systems, typically using infrared grids - which rely heavily on the user's finger size. These guidelines are less relevant for most modern devices that use capacitive or resistive touch technology.
From the mid-2000s, smartphone operating systems makers have announced standards, but this varies between manufacturers, and allows for significant size variations based on technological changes, so it does not fit from the perspective of human factors.
Much more important is the accuracy that humans have in choosing a target with a finger or a stylus pen. The accuracy of user selection varies by position on the screen: the most accurate user in the center, less so on the left and right edges, and the least accurate on the top edge and especially the bottom edge. The accuracy of R95 (the radius required for 95% target accuracy) varies from 7 mm (0.28 inches) in the middle to 12 mm (0.47 inches) in the lower corners. Users are unconsciously aware of this, and take more time to select smaller targets or on the edge or corners of the touch screen.
This user inaccuracy is the result of parallax, visual acuity, and the speed of feedback loop between the eyes and fingers. The accuracy of human fingers is much, much higher than this, so when assistive technology is provided - as in screen magnifiers - the user can move their finger (after touching the screen) with precision as small as 0.1 Ã,mm (0.004Ã,.
Hand position, digit used and switch
Users of handheld and portable touchscreen devices hold them in various ways, and routinely change their holding and selection methods to adjust position and input type. There are four basic types of hand-held interactions:
- Hold at least with both hands, tap with one thumb
- Grasp with two hands and knock with both thumbs
- Clasp with one hand, tap on the finger (or rarely, thumb) from the other side
- Hold the device in one hand, and tap with your thumb from the same hand
Use rates vary greatly. While two thumb taps are rare (1-3%) for many common interactions, it is used for 41% of the typing interactions.
In addition, the device is often placed on the surface (table or desk) and tablets are mainly used in the stands. Users can show, vote or gesture in this case with their finger or thumb, and various uses of this method.
Coupled with haptics
The touch screen is often used with a haptic response system. A common example of this technology is the vibration feedback provided when the buttons on the touch screen are tapped. Haptics are used to enhance the user experience with touch screens by providing simulated touch feedback, and can be designed to react immediately, partially against the response latency on the screen. Research from the University of Glasgow (Brewster, Chohan, and Brown, 2007, and the latest Hogan) shows that touch screen users reduce input errors (by 20%), increase input speeds (by 20%), and lower their cognitive load 40%) when the touch screen is combined with haptics or tactile feedback.
The extended use of gestural interfaces without the user's ability to rest their arms is referred to as a "gorilla arm". This can lead to fatigue, and even stress injuries recur when routine is used in work settings. Certain initial pen-based interfaces require the operator to work in this position for most weekdays. Allowing users to put their hands or arms on the input device or the surrounding frame is the solution to this in many contexts. This phenomenon is often referred to as a prima facie example of movement that should be minimized with proper ergonomic design.
Unsupported touchscreens are still quite common in applications such as ATMs and data kiosks, but are not a problem as regular users are only involved for a short and very extensive period.
Fingerprint
Touchscreens can suffer fingerprint problems on the screen. This can be reduced by the use of materials with an optical coating designed to reduce the visible effects of fingerprint oil. Most modern smartphones have an oleophobic coating, which reduces the amount of oil residue. Another option is to install a matte-finish anti-glare screen protector, which creates a slightly rough surface that is not easy to store stains.
src: cdn-shop.adafruit.com
See also
src: www.vision2watch.com
Note
src: cdn-shop.adafruit.com
References
- Holzinger, A. (2003). "Finger Not Mouse: Touch Screen as a means to improve Universal Access". In: Carbonell, N.; Stephanidis C. (Eds): Universal Access, Lecture Notes in Computer Science . Lecture Notes in Computer Science. 2615 : 387-397. doi: 10.1007/3-540-36572-9_30. ISBN: 978-3-540-00855-2.
src: www.tsitouch.com
External links
- Howstuffworks - How does the touch screen monitor know where you are touching?
- How does the touch screen work?
- What are the different types of touch screen technology
- From the touch screen to the surface: A brief history of touch screen technology
- Bibliography annotated references to the touchscreen, motion and pen computation
- Part 1: The Basics of Touch Technology Capacitive Projection, Geoff Walker, June 2014
- Notes about Pen-based Computing History on YouTube
Source of the article : Wikipedia
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