Compare Touch screen technologies

1. Introduction 2
2. Comparing CRT and Flat Panel Displays 3
3. Touch Panel Technology 5
4. Applications of Touch screen 7
5. Different Technologies 8
6. Comparing Different Technologies 10
7. Benefits of Touch screen interface 12



1.INTRODUCTION

The use of a touch screen interface for the control and input of a given computer system is becoming more popular on the plant floor and other hazardous environments. At one point keyboards were the only means of interfacing with a PC until the development of a "pointing device" i.e., the mouse. Since then other pointing devices have gained favor such as joysticks and track-balls. Today, virtually all software applications require the use of a pointing device such as a mouse.
Another such "pointing device" is a touch screen which is the most direct form of operator interface since the operator is touching the actual area of the screen they want activated. It also serves as an intuitive tool for operators that are not as familiar with basic computer pointing devices. Touch screens have found their way onto the plant floor for a number of reasons. One of these reasons is to eliminate the need for a keyboard or traditional mouse and provide operators with graphical icons that represent the specific task at hand. This serves to keep operators focused on the application and can be used by virtually all operators of regardless of their level of computer knowledge.
Another consideration for touch screen technology in lieu of a traditional mouse/keyboard is the fact it is more industrial grade and resilient to the elements found on the traditional plant floor. Most touch screen technologies can also be used with a gloved hand eliminating the need for the operator to remove their gloves prior to operating the computer system.
Touch is one of the simplest, most instinctive, and universal human actions. There are several reasons to use touch technologies, which include limiting an end-user's access to a computer in kiosk-type applications as well as harsh environments where data entry needs to be balanced against sealing and protecting the computer. Touch technologies allow both of these applications to be retrofitted to computers utilizing one of several technologies currently available. A touch screen is the simplest, most direct way for a person to interact with a computer. Though it is a relatively new technology - two of the larger touch screen manufacturers claim to have started their operations in the 70s - the basic way users interact with a touch screen is age old: you point to what you want. It's intuitive for virtually every child and adult in the world. Companies in a broad cross-section of industries have successfully harnessed the power of a touch screen for a wide variety of applications. Airlines use them to simulate aircraft cockpits and train their pilots to fly. Realtors use them to put full-color images of homes for sale a fingertip away from homebuyers. Greeting card companies use them to let customers create their own one-of-a-kind cards. Restaurants use them to simplify their point-of-sale terminals. Medical schools use them to teach student nurses how to respond to crisis situations.



2.COMPARING CRT AND FLAT PANEL DISPLAYS

The two most common types of monitors that are being used today are CRT (Cathode Ray Tube) monitors and LCD (Liquid Crystal Display) monitors. CRT type monitors are the traditional monitors that we have been using for years. LCD type monitors are based on a newer technology and are becoming very popular, mainly because they have great space and energy saving advantages over CRT monitors. CRT and LCD monitors are based on completely different technologies, and thus have quite different display characteristics

Physical Size
One of the biggest advantages of LCD monitors is that they are compact and lightweight. An LCD monitor is based upon a very thin screen as opposed to the bulky tube of a CRT monitor. This means that not only do they take up less of your desktop space; they can also be used in many places where a larger CRT monitor cannot fit. A 12.1" LCD monitor with a stand takes up only about one-third of the desk space of a typical 14" CRT monitor.

Display Size
Thanks to advances in LCD technology, color flat panel LCD monitors are now available that are comparable in screen size to traditional CRT monitors. A 12.1" LCD display has only a slightly smaller viewing area than a typical 14" CRT monitor. Newer, larger LCD monitors are also appearing that have 15", 17", and even larger screen sizes that are comparable to the largest CRT monitors. One thing to note is that LCD monitors are typically sized by their actual viewable diagonal measurement, but CRTs typically are not. For example, the viewable area on a 17" LCD monitor will typically measure 17" diagonally, but the viewable area on a CRT monitor will typically only measure 16" diagonally.
Colors
Most CRT monitors are capable of displaying unlimited colors. Some LCD monitors are only capable of hundreds or thousands of colors, but many of the newer LCD's are capable of unlimited colors.
Resolution
An important issue with LCD monitors is resolution. CRT monitors are usually capable of displaying multiple video resolutions, each with the same quality. LCD monitors, however, usually has what is called a Native resolution, or the resolution that it displays best. The native resolution is generally the highest resolution that the LCD can display and this is the display resolution that will appear the crispest/sharpest.

Brightness
Typically, brightness is not a concern with CRT monitors. LCD monitors are backlit and have different levels of brightness. The brightness rating for an LCD monitor is commonly referred to as 'nits', and commonly ranges from 70 to 250 nits. The higher the nits, the brighter the display
Viewing Angle
Another issue with the LCD monitor is the viewing angle. A CRT screen can be looked at from a very wide angle, practically from the side, but an LCD monitor typically has a smaller viewing angle, needing to be viewed more directly from the front. From the side, the image on an LCD screen can seem to disappear, or invert colors. Newer displays that are coming out have wider viewing angles so this is not as much of an issue as it has been in the past.
Power Consumption and Radiation Emission

Besides being compact and space saving, LCD displays offer several other benefits. For one, LCD monitors consume much less energy than CRT monitors. This makes the LCD great for laptop and portable computers. Secondly, CRT monitors are known to emit harmful radiation, whereas LCD monitors do not.

Price

CRT monitors are generally more affordable than LCD monitors. In the past LCD monitors have been very expensive but their costs have come down quite a bit in the last 1-2 years. One thing to consider is the up-front cost versus the long-term cost. A CRT monitor will cost less up front but will use more energy than a flat panel monitor. An LCD monitor will cost more up front but will conserve energy in the long run. The energy savings may not be much for an individual user, but if you are looking at a corporate office where 50 displays are in use, the energy savings might be more of an issue



3.Touch Panel Technology

How it works?
Most of the technologies discussed here operate on the principle of dividing the screen image area into a predetermined grid (dependent upon screen size and resolution capabilities). Touching one of the quadrants of the menu selection causes a subroutine to execute in the same manner as typing the command at the prompt line or you would with a mouse. The first touch screen was created by adding a transparent surface to a touch-sensitive graphics digitizer and sizing it to fit a computer monitor. The purpose was to increase the speed data that could be entered into a computer. Today, the touch screen has been transformed into a more user-friendly and environmentally robust replacement for the computer keyboard and mouse. Because of that, touch is changing the world. With a touch screen, people with little or no computer experience can instantly work with complex software programs, without even being aware they're doing it. And computers can go to work in places where a keyboard or mouse would too cumbersome, fragile, or impractical.

A basic touch screen has three main components: a touch sensor, a controller, and a software driver. The touch screen is an input device, so it needs to be combined with a display and a PC or other device to make a complete touch input system.










1. Touch Sensor
A touch screen sensor is a clear glass panel with a touch responsive surface. The touch sensor/panel is placed over a display screen so that the responsive area of the panel covers the viewable area of the video screen. There are several different touch sensor technologies on the market today, each using a different method to detect touch input. The sensor generally has an electrical current or signal going through it and touching the screen causes a voltage or signal change. This voltage change is used to determine the location of the touch to the screen.




2. Controller
The controller is a small PC card that connects between the touch sensor and the PC. It takes information from the touch sensor and translates it into information that PC can understand. The controller is usually installed inside the monitor for integrated monitors or it is housed in a plastic case for external touch add-ons/overlays. The controller determines what type of interface/connection you will need on the PC. Integrated touch monitors will have an extra cable connection on the back for the touch screen. Controllers are available that can connect to a Serial/COM port (PC) or to a USB port (PC or Macintosh). Specialized controllers are also available that work with DVD players and other devices. 3. Software Driver
The driver is a software update for the PC system that allows the touch screen and computer to work together. It tells the computer's operating system how to interpret the touch event information that is sent from the controller. Most touch screen drivers today are a mouse-emulation type driver. This makes touching the screen the same as clicking your mouse at the same location on the screen. This allows the touch screen to work with existing software and allows new applications to be developed without the need for touch screen specific programming. Some equipment such as thin client terminals, DVD players, and specialized computer systems either do not use software drivers or they have their own built-in touch screen driver.
So it is clear that the touch sensor and the software are the important links for any touch screen panels. There are different kinds of Sensor technologies available. Each technology has its on merits and drawbacks depending on the application and the environment.





4.APPLICATIONS OF TOUCH SCREENS

Regardless of the industry or application, the essential benefits touch screen technology provides remain unchanged:
§ Touch screens enable people to use computers instantly, without any training whatsoever
§ Touch screens virtually eliminate operator errors because users select from clearly defined menus 
§ Touch screens eliminate keyboards and mice, which many find intimidating and cumbersome to use
§ Touch screens are rugged enough to stand up to harsh environments where keyboards and mice often get damaged
§ Touch screens provide fast access to any and all types of digital media, with no text-bound interface getting in the way
§ Touch screens ensure that no space - on the desktop or elsewhere - is wasted, as the input device is completely integrated into the monitors
§ Simplifies the User/MPC interface
§ Durable in harsh conditions
§ Suitable for all environments
§ Greater accuracy
§ Smaller footprint

Where is Touch Used?

§ In Military command and control applications
§ In Kiosks
§ In industrial environments for control and automation
§ In hospitals
§ In retail locations
§ At tourist destinations
§ In schools for computer based training
§ Assistive technology



5.DIFFERENT TECHNOLOGIES

1. Resistive Technology





A thin glass substrate is "sandwiched" in between two layers of a plastic overlay. On the surface of the glass substrate is a tin oxide coating onto which a slight electrical current is constantly applied. The plastic overlay and the glass substrate are separated by hundreds of microscopic dot separators. When pressure is applied to the outside of the plastic overlay the two currents touch and a ground occurs. The X and Y coordinates of the touch are then detected by the touch screen controller card that is installed in the PC.

2. Capacitive Technology

A glass substrate with a tin oxide coating is charged with a slight electrical current. When the human hand touches the surface it causes a current draw at that point. The X and Y coordinates can then be determined from that point. It is a durable technology that is used in a wide range of applications including point-of-sale systems, industrial controls, and public information kiosks. It has a higher clarity than resistive technology, but it only responds to finger contact and will not work with a gloved hand or pen stylus.













3.Surface Acoustical Wave (SAW) Technology




A set of transducers emits a mechanical "wave" across the horizontal axis and vertical axis via reflective arrays. Receivers on the other side pick up the flow of these waves. If the surface of the screen is touched then a disruption in the wave occurs and the software determines the X and Y coordinates. . The SAW screen is a good choice for applications where image clarity is important, but it may not perform well in extremely dirty or dusty environments. Responds to finger or soft rubber tipped pointers.

4.Pen touch Capacitive Technology

Pen Touch Capacitive touch screen technology screen combines durable capacitive technology with a tethered pen stylus. The screen can be set to respond to finger input only, pen input only, or both. The pen stylus is a good choice for signature capture, on-screen annotations, or for applications requiring precise input.

5. Near Field Imaging technology

Near Field Imaging touch screen technology as one of the custom LCD touch monitor solutions it is an extremely durable screen that is suited for use in industrial control systems and other harsh environments. This rugged screen type is not affected by most surface contaminants, scratches, or vibration. Responds to finger or gloved hand

6. Infrared Technology

Infrared touch screen technology with the Plasma display solutions this is the only type of touch technology that we have available for large displays such as 42-inch Plasma screens. It is a durable technology that offers high image clarity. Responds to any input device or stylus.




6.Comparing Different Technologies.


§ 4-Wire Resistive Touch screens

Advantages

High touch resolution
Pressure sensitive, works with any stylus
Not affected by dirt, dust, water, or light
Affordable touch screen technology
Disadvantages
75 % clarity
Resistive layers can be damaged by a sharp object
Less durable then 5-Wire Resistive technology

§ Capacitive Touch screens
Advantages
o High touch resolution
o High image clarity
o Resistant to scratching
o Not affected by dirt, grease, moisture



Disadvantages
o Must be touched by finger, will not work with any non- conductive inputs, Cannot be used with gloves.
§ Infrared Technology
Advantages
o Good clarity
o Can be used with gloved hands
Disadvantages
o Not suitable for direct wash down
o Subject to activation by flying objects

§ Surface Acoustical Wave (SAW) Technology
Advantages
o Good clarity
o Can be used with gloved hands
High transmissivity - >92%
High resolution - 900 x 900, smooth mouse tracking and small target activation
Low parallax with spherical screen that conforms to CRT faceplate
Impervious to scratching by all but the hardest materials
Only technology with Z axis control

Disadvantages
o Pressure hosedown may cause unwanted target selection
o Dust, oil or grease on surface of touch screen may cause malfunction or unwanted target selection


WHICH TECHNOLOGY IS BEST?
Once the decision to use a touch screen has been made the next decision is which touch screen technology is best. This can easily be determined by looking at the application, where the touch screen will be used and the environment it will be operating in. There is four touch screen technologies that are generally used: Resistive, Infrared, Capacitive and Surface Acoustical Wave (SAW). They all have their pros and cons as outlined below. Capacitive for example cannot be used with gloves but can be washed down whereas Infrared can be used with gloves but should not be washed down.

In India capacitive touch technology or SAW is recommended for all application because of its ability to perform in contaminated environments. Contaminants such as grease, liquid and dust do not interfere with the touch screen's operation. It is the most durable and robust touch screen available today and to maintain watertight seal, can be set off by wash down

7.Benefits of Touch Interface

Many years ago, touch screens were an exotic, expensive interface for demanding applications like air-traffic and nuclear power-plant control. Not anymore! Companies across a broad spectrum of industries have successfully harnessed the power of touch for a wide variety of applications. Yet the essential benefits provided by touch technology remain unchanged
Fast, faster, fastest
Touch screens provide fast access to any and all types of digital media, with no text-bound interface getting in the way. It takes time for the user to grab a mouse or use a keyboard or trackball and coordinate it with what needs to be activated on the display. Faster input can mean better customer service in restaurants, hotels, movie theaters, and retail stores, which results in increased customer loyalty. In other cases, such as in-vehicle control or security equipment, being even one second faster can make all the difference.
Touch makes everyone an expert
Reaching out for what you want is an instinctive gesture. Using touch is just as simple: you simply point at what you want. Although some people still shy away from computer keyboards, mice, or trackballs, there is no hesitation when they can just touch a screen. Users feel comfortable that they cannot "do anything wrong"; they instinctively understand how to use the interface. Touch screen systems make everyone an "expert user" from the first touch—whether it’s a person consulting a kiosk, a worker controlling an industrial process, a nurse entering a patient’s information, or a waiter entering an order
Reduced costs
Using a touch interface can effectively increase operator accuracy, reduce training time, and improve overall operational efficiencies, thus keeping costs down. In the retail environment, for example, a properly designed touch interface can improve each operator’s accuracy, while maintaining optimum checkout speeds. Users can respond quickly without making significant errors. Also, touch-based point-of-sale (POS) systems streamline the returns and refunds process by reducing the time it takes a customer to return merchandise; they also improve loss-prevention management. In addition, compared to traditional training methods, using touch screens can drastically reduce training time, since touch technology is intuitive and requires no special skills to learn. Moreover, the flexibility of touch technology can significantly contribute to cost reductions: it creates operational efficiencies by simplifying procedures and reduces the need for additional capital investment.
Compact and Handy
Space is valuable, so you want to use it as efficiently as possible. Touch monitors ensure that no space—on the desktop or elsewhere—is wasted, since the input device is completely integrated into the display. Flat LCD touches monitors help save even more space. And there are no keyboard or mouse cords in front of the monitor to get tangled or damaged, or to gather dust
Durable and Easy to Clean
A touch screen is made of glass or a similar hard-coated surface. So it’s easy to clean and therefore extremely well suited for the typical environments found in restaurants, hospitals, and the food and pharmaceutical industries. Most of the touch screens can be used with gloves, which is great for applications where hygiene is particularly important or where temperature or workplace safety rules require the use of gloves. We offer touch screen systems that are not affected by dirt, dust, grease, or liquid droplets. They are even rugged enough to stand up to harsh environments where keyboards and mice often get damaged

When ease of use is required
Touch screen-based systems virtually eliminate errors because users select from clearly defined menus. The information on each screen is limited in number and options, thus providing step-by-step, fail-safe sequences to guide the user through complex procedures. This greatly simplifies medical diagnostics applications—for example, where voluminous databases must be accessed quickly and easily. Touch screens are also useful in simplifying process-control applications involving many buttons or switches, and for applications where system contents require protection from unauthorized entry.