A display screen that is sensitive to the touch of a finger or stylus. Widely used on ATM machines, retail point-of-sale terminals, car navigation systems, medical monitors and industrial control panels, the touch screen became wildly popular on handhelds after Apple introduced the iPhone in 2007.
Touch screens offer several advantages, the primary one being the infinite ways the user interface can be designed and changed compared to a fixed set of physical buttons. If there is no hardware keyboard on the unit, a "soft" keyboard can be displayed on screen whenever text must be typed in. Touch screens are also able to accept hand printing, handwriting, graphics and finger movements (see multitouch). Touch screens can also be made resistant to harsh environments, compared to ordinary computer monitors.
All touch screens "digitize" the point of contact on screen into an X-Y coordinate. They fall into two major categories: active digitizer and passive touch screen.
Active Digitizer Tablets
Although graphics tablets have been used in computer-aided design (CAD) and other graphics applications for years, the digitizer technology was embedded behind the screen of tablet PCs in order to operate the computer with the precision of a mouse.
A stylus is used to transmit an electromagnetic signal to an X-Y grid, which has a very high resolution. Either by being wired to the unit or from a tiny battery, the stylus may be self powered, or it may obtain its power from the tablet surface, which alternates between transmitting and receiving. Tablet PCs may use both active digitizer and passive touch screen technologies, offering both stylus-based precision and finger-based simplicity. See digitizer tablet.
Passive Touch Screens
Resistive
Resistive screens are pressure sensitive and can be touched with a finger, stylus or just about any pointed object. They use two active layers: a flexible plastic layer on top of a rigid plastic or glass layer, with insulated spacers in between. The layers are coated with indium tin oxide, and different voltages are applied across the coatings, typically alternating between the layers. When touched, the front layer picks up the voltage from the back, and the back layer picks up the voltage from the front, enabling the controller to determine the X-Y location.
Although the least expensive, the resistive method blocks up to 30% of the light from the CRT or LCD screen due to the multiple layers and coatings.
Capacitive
The capacitive method uses only one active layer: a metallic coated glass panel, thus allowing more light to come through. Voltage is applied to the corners of the screen, and when a finger touches the screen, it draws a tiny amount of current. The controller computes the X-Y location from the change in capacitance caused by that touch point. Because the human body absorbs current, the finger must be used and not a plastic stylus.
A variation called "projected capacitive" uses a sensor grid sandwiched between two glass layers. When the screen is touched, the controller computes the X-Y location from the change in capacitance in the grid. The grid also enables two-finger touching like Apple's multitouch iPhone. Although the grid is embedded and protected, the screen can be overlaid with a clear, heavy-duty glass layer for more protection.
Acoustic Waves and Infrared
Acoustic waves or infrared signals are transmitted across the screen's external surface from the top and side. When the screen is touched, receivers at the opposite ends form an X-Y matrix and sense the blocked signals. Since these methods do not use active layers over the screen, they do not block any light. The screens can also be overlaid with a clear, heavy-duty glass layer for protection.
Pressure Sensitive
Keytec makes a wide variety of resistive touch screens that can be touched with the finger or any stylus-like object. When the plastic layer is pushed into the glass layer, it diverts the current. (Image courtesy of Keytec, Inc., www.magictouch.com)
Touch Screens Are Everywhere
The touch screen has become widely used for industrial and consumer applications. It offers the ability to display myriad combinations of controls on the same screen, which would otherwise be cumbersome with physical buttons.
Touch screens offer several advantages, the primary one being the infinite ways the user interface can be designed and changed compared to a fixed set of physical buttons. If there is no hardware keyboard on the unit, a "soft" keyboard can be displayed on screen whenever text must be typed in. Touch screens are also able to accept hand printing, handwriting, graphics and finger movements (see multitouch). Touch screens can also be made resistant to harsh environments, compared to ordinary computer monitors.
All touch screens "digitize" the point of contact on screen into an X-Y coordinate. They fall into two major categories: active digitizer and passive touch screen.
Active Digitizer Tablets
Although graphics tablets have been used in computer-aided design (CAD) and other graphics applications for years, the digitizer technology was embedded behind the screen of tablet PCs in order to operate the computer with the precision of a mouse.
A stylus is used to transmit an electromagnetic signal to an X-Y grid, which has a very high resolution. Either by being wired to the unit or from a tiny battery, the stylus may be self powered, or it may obtain its power from the tablet surface, which alternates between transmitting and receiving. Tablet PCs may use both active digitizer and passive touch screen technologies, offering both stylus-based precision and finger-based simplicity. See digitizer tablet.
Passive Touch Screens
Resistive
Resistive screens are pressure sensitive and can be touched with a finger, stylus or just about any pointed object. They use two active layers: a flexible plastic layer on top of a rigid plastic or glass layer, with insulated spacers in between. The layers are coated with indium tin oxide, and different voltages are applied across the coatings, typically alternating between the layers. When touched, the front layer picks up the voltage from the back, and the back layer picks up the voltage from the front, enabling the controller to determine the X-Y location.
Although the least expensive, the resistive method blocks up to 30% of the light from the CRT or LCD screen due to the multiple layers and coatings.
Capacitive
The capacitive method uses only one active layer: a metallic coated glass panel, thus allowing more light to come through. Voltage is applied to the corners of the screen, and when a finger touches the screen, it draws a tiny amount of current. The controller computes the X-Y location from the change in capacitance caused by that touch point. Because the human body absorbs current, the finger must be used and not a plastic stylus.
A variation called "projected capacitive" uses a sensor grid sandwiched between two glass layers. When the screen is touched, the controller computes the X-Y location from the change in capacitance in the grid. The grid also enables two-finger touching like Apple's multitouch iPhone. Although the grid is embedded and protected, the screen can be overlaid with a clear, heavy-duty glass layer for more protection.
Acoustic Waves and Infrared
Acoustic waves or infrared signals are transmitted across the screen's external surface from the top and side. When the screen is touched, receivers at the opposite ends form an X-Y matrix and sense the blocked signals. Since these methods do not use active layers over the screen, they do not block any light. The screens can also be overlaid with a clear, heavy-duty glass layer for protection.
Pressure Sensitive
Keytec makes a wide variety of resistive touch screens that can be touched with the finger or any stylus-like object. When the plastic layer is pushed into the glass layer, it diverts the current. (Image courtesy of Keytec, Inc., www.magictouch.com)
Touch Screens Are Everywhere
The touch screen has become widely used for industrial and consumer applications. It offers the ability to display myriad combinations of controls on the same screen, which would otherwise be cumbersome with physical buttons.
 | Reproduced with permission from Computer Desktop Encyclopedia. Copyright (c) 1981-2009 The Computer Language Company Inc. All rights reserved. |
Additional Resources
- Dog Dodge for iPhone 1.1 (Mobile)
- Dog Dodge for iPhone is a fast paced game that requires you to steer your dog around the screen as quickly as possible to gather as many fire hydrants as you can before your lives run out. Crazed cats are trying to run you down. Their unnerving honking cars will...
- Software downloads 2009-11-23
- Illness Tracker for iPhone 1.7 (Mobile)
- With Illness Tracker for iPhone, simplifies this task by allowing you to touch a day on the calendar to record various notes. Your data then appears as icons on the calendar, allowing you to see your records at a glance. Keep track of yourself and an unlimited number of people....
- Software downloads 2009-11-23
- Green Thumb Free for iPhone 1.1 (Mobile)
- Green Thumb Free for iPhone is an original, one-thumb casual game. Touch the screen once to drop water. Seeds that hit the water make flowers. Seeds touching flowers earn more points, so longer chains of flowers boost your score quicker. Choose your drop spot carefully so that all seeds turn...
- Software downloads 2009-11-23
- Green Thumb for iPhone 1.1 (Mobile)
- Green Thumb for iPhone is an original, one-thumb casual game. Touch the screen once to drop water. Seeds that hit the water make flowers. Seeds touching flowers earn more points, so longer chains of flowers boost your score quicker. Choose your drop spot carefully so that all seeds turn into...
- Software downloads 2009-11-23
- The Merck Manual for iPhone 1.0 (Mobile)
- The Merck Manual for iPhone designed specifically for the iPhone and iPod Touch, the app has an easy-to-use interface for finding the right information quickly. In particular, an emergencies and injuries section that is accessible from the home screen was developed expressly for this application. It features access the content...
- Software downloads 2009-11-23
- T-Mobile Tap photos
- The T-Mobile Tap is Huawei's first major touch screen phone for the U.S. market. by CNET News.com
- Image galleries 2009-11-20
- Samsung Mythic photos
- The Samsung Mythic is a good touch screen multimedia phone from AT&T that also supports AT&T Mobile TV. by CNET News.com
- Image galleries 2009-11-20
- Chrome OS - The good, the bad and the ugly, and how it fits in with Windows, Mac and Linux
- Chrome OS - The good, the bad and the ugly, and how it fits in with WindowsI gave it some thought too and realized that Chrome OS only has the bad and the ugly. There is nothing good about it. All data stored in the cloud, and on Google's...
- Discussion threads 2009-11-20
- Galaxy Impact for iPhone 1.2.1 (Mobile)
- Galaxy Impact for iPhone is a timeless classic brick game now enters the world of iPhone.It takes advantage of iPhone touch screen and is easy to use. With the very spirit of classic brick-break game, Galaxy Impact for iPhone comes with the following features: touching anywhere on the screen, you...
- Software downloads 2009-11-20
- Shape Crazy for iPhone 2.4 (Mobile)
- Shape Crazy for iPhone is a quick paced game where you need quick fingers and a quick mind. The top of the screen will have three colored shapes. The bottom of the screen will have 15 colored shapes. Your goal is to remove the targets that match the colored shapes...
- Software downloads 2009-11-20
- Pinned tabs? (Gallery: Chrome OS revealed)
- Easy to see why Google wants thisAll roads lead to Google and advertizing.RE: Pinned tabs? (Gallery: Chrome OS revealed)Aouch!! what is this crap os is??? Bad Bad Bad idea!!!RE: Pinned tabs? (Gallery: Chrome OS revealed)NO thanks. I am not in Kindergarten.RE: Pinned tabs? (Gallery: Chrome OS revealed)I think it...
- Discussion threads 2009-11-19
- Google makes Chrome OS open source today
- I like itThe ChromeOS demo looked pretty cool!I'm almost 100% webapp-based already, so I could see myself using a simple, fast & no maintenance OS like that the majority of the time.I like it too, but, for me, I need to compile and run programs locally. I would imagine that...
- Discussion threads 2009-11-19
- Hands-on with the HTC HD2, most impressive Windows Mobile device to date
- I like what HTC is doingYou've got the Hero and the HD2. I'd like to see what the difference is in performance between the two, but the Hero has a slower processor. Personally, I like the Windows Mobile platform, and it is the best option for Windows-based IT...
- Discussion threads 2009-11-19
- Apple Tablet - Unofficial, unannounced ... but still delayed
- You guys have been asking...You guys have been asking for a Mac tablet for years already, while we have been able to get tablet PCs for many years now, in many different form factors and from many different vendors.Yet when you close your world off by relying solely on Apple,...
- Discussion threads 2009-11-19
- FCC wants public comment on digital democracy - voting online
- Online Voting - Destroying the integrity and fabric of democracy.On-line voting without safe guards against vote selling and guarantee that each vote was registered in private invalidates the intent and meaning of "one person, one vote."It's bad enough that this hole currently exists with the current mail-in voting process.RE: FCC...
- Discussion threads 2009-11-19
- Amazon slashes price of Palm Pre to $79.99, Pixi to $24.99
- I don't want ......ANY misleading bargain with a two or three year contract. Sell me the HW at a fair price and let me select the carrier and package of my choice.I am not an idiot. RE: Amazon slashes price of Palm Pre to $79.99, Pixi to $24.99When you limit...
- Discussion threads 2009-11-19
- Microsoft designs laptop for developer giveaway
- Windows division president Steven Sinofsky took his Windows team through the process of designing and building a Windows 7 laptop in conjunction with Acer. LOS ANGELES--As a software guy, Windows division president Steven Sinofsky readily admits that he had little idea of all that goes into building a laptop....
- News items 2009-11-19
- Big Screen Lite for iPhone 1.0 (Mobile)
- Big Screen Lite for iPhone application functions as web browser. It does not hinder the screen with tool bars or palettes but frees all but a small corner for viewing your website. It allows the user to perform all the functions necessary for browsing from one site to another, while...
- Software downloads 2009-11-19
- Running Log for iPhone 1.3 (Mobile)
- With Running Log for iPhone record your workouts and rest days, and see your history and trends on the visual calendar and summary. To log a run, touch any calendar day. Then record: distance, duration, effort level, type of run , route name, group runs, rest days, and freeform notes....
- Software downloads 2009-11-19
- FastStone Image Viewer 4.0 (Windows)
- FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor. It has a nice array of features that include image viewing, management, comparison, red-eye removal, emailing, resizing, cropping and color adjustments. Its innovative but intuitive full-screen mode provides quick access to EXIF information, thumbnail browser and major...
- Software downloads 2009-11-19
Neighboring Terms
Premier Vendor Content Whitepapers, webcasts & resources from our Power Center Sponsors
- Save time with automated shipping solutions
-
The Business Essentials Guide provides you useful tools and templates to help grow your business and save you time with automated shipping solutions.
- Visit the UPS Business Essentials Guide
- Keep Up With The Latest In Document Management with The DocuMentor.
-
Doc delivers the scoop on today's enterprise content management, printer maintenance, and all other issues related to document management. It's the DocuMentor Blog.
- Learn more >>
- New Online Dashboard for IT Leaders
-
Read about top issues IT decision-makers face every day, plus get cost-effective solutions to real-life IT problems.
- Learn more >>
- Microsoft Dynamics CRM Online - Free Six-Month Trial for Eligible Organizations
-
Microsoft Dynamics CRM Online provides fast online access, simple contact management and better sales performance for a low monthly cost - the best value on the market today.
- Learn more about the free, six-month trial offer>>
Popular Sanity Saver Videos
