18-08-2011, 10:08 AM
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INTRODUCTION :
With the advent of the I-Phone, touch screen technology has reached the mainstream. Every call carrier now offers their own version of touch phones and there have been rumors of completely touch-interfaced computers. While touch screen technology has been around since the 1960’s, the media buzz has taken off in the past two to three years. Touch screen monitors have become more and more commonplace since their prices have dropped in the past decade. Touch screens are found in ATMs, PDAs, cellular phones, grocery checkout counters, airport check-in counters, and many other devices that we use every day.
Simply put, a touch screen is a display that can detect the presence and location of a touch within the display area. The term generally refers to touch or contact to the display of the device by a finger or hand. Touch screens provide an alternative user-interface to the historical mouse and keyboard of traditional computers.
Touch screens first became a research interest in the second half of the 1960’s. In 1971 Samuel Hurst developed the first “touch sensor.” One of the first places where they gained some visibility was in a computer-assisted learning terminal that came out in 1972 as part of the PLATO project. This was the first step in commercializing touch screen technologies. Touch screens became widely used in kiosk and point of sale systems in banks and stores. In 1983, the first touch screen computer, the HP-150, reached the market. Since then we have seen the introduction of advanced touch screen technologies leading to the commercialization of tablet PCs, PDAs, and touch-screen phones.
There are several different types of touch screen technology. The resistive system is based on the use of two parallel conductive and resistive metallic layers. The capacitive system uses a monitor with a built up charge on its surface. When a person touches the surface, the charge is transmitted to the user, thus allowing the computer to recognize the touch. A third technology is the surface acoustic wave. This recognizes touch by using transducers that can analyze at what instance a wave was disturbed.
In this presentation, we will touch on the history behind touch screen technology while also explaining in detail how the different methods of touch screen technologies work. More specifically, we will spend a considerable amount of time describing the different technologies found in devices that use touch screen. We will also delve into the current commercial applications and practical benefits of touch screens. Finally, we will comment on the future applications and potentials of touch screen technology.
HISTORY
The first touchscreen was a capacitive touch screen developed by E.A. Johnson at the Royal Radar Establishment, Malvern, UK. The inventor briefly described his work in a short article published in 1965 and then more fully - along with photographs and diagrams - in an article published in 1967. A description of the applicability of the touch technology for air traffic control was described in an article published in 1968.
Touchscreens first gained some visibility with the invention of the computer-assisted learning terminal, which came out in 1972 as part of the PLATO project. Touchscreens have subsequently become familiar in everyday life. Companies use touchscreens for kiosk systems in retail and tourist settings, point of sale systems, ATMs, and PDAs, where a stylus is sometimes used to manipulate the GUI and to enter data.
From 1979–1985, the Fairlight CMI was a high-end musical sampling and re-synthesis workstation that utilized light pen technology, with which the user could allocate and manipulate sample and synthesis data, as well as access different menus within its OS by touching the screen with the light pen. The later Fairlight series III models used a graphics tablet in place of the light pen.
The HP-150 from 1983 was one of the world's earliest commercial touchscreen computers. Similar to the PLATO IV system, the touch technology used employed Infrared transmitters and receivers mounted around the bezel of its 9" Sony Cathode Ray Tube (CRT), which detected the position of any non- transparent object on the screen.
An early attempt at a handheld game console with touchscreen controls was Sega’s intended successor to the Game Gear, though the device was ultimately shelved and never released due to the expensive cost of touchscreen technology in the early 1990s. Touchscreens would not be popularly used for video games until the release of the Nintendo DS in 2004.
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 is starting to change with the commercialization of multi-touch technology.
The popularity of smartphones, PDAs and tablet computers, portable video game consoles and many types of information appliances is driving the demand and acceptance of common touchscreens, for portable and functional electronics, with a display of a simple smooth surface and direct interaction without any hardware between the user and content, fewer accessories are required.
Touchscreens are popular in hospitality, and in heavy industry, as well as kiosks such as museum displays or room automation where keyboard and mouse systems do not allow a suitably intuitive, rapid, or accurate interaction by the user with the display's content.
Historically, the touchscreen sensor and its accompanying controller-based firmware have been made available by a wide array of after-market system integrators, and not by display, chip, or motherboard manufacturers. Display manufacturers and chip manufacturers worldwide have acknowledged the trend toward acceptance of touchscreens as a highly desirable user interface component and have begun to integrate touchscreen functionality into the fundamental design of their products.
CHAPTER 1 : RESISTIVE TOUCHSCREEN TECHNOLOGY
1.1 Introduction
Resistive touchscreens are touch sensitive computer displays composed of two flexible sheets coated with a resistive material and separated by an air gap or Microdots. The resistive coating is made up of Idium-Tin oxide. It is the most simple technology and hence it is widely used.
When contact is made with the surface of touchscreens, the two sheets are pressed together. On these two sheets there are horizontal and vertical lines that when pushed together, register the precise location of the touch. Because the touchscreen senses input from contact with nearly any object (finger, stylus/pen, palm) resistive touchscreens are a type of "passive" technology.
During the operation of a four-wire touchscreen, a uniform, unidirectional voltage gradient is applied to the first sheet. When the two sheets are pressed together, the second sheet measures the voltage as distance along the first sheet, providing the X coordinate. When this contact coordinate has been acquired, the uniform voltage gradient is applied to the second sheet to ascertain the Y coordinate. These operations occur within a few milliseconds, registering the exact touch location as contact is made.
Resistive touchscreens typically have high resolution (4096 x 4096 DPI or higher), providing accurate touch control. Because the touchscreen responds to pressure on its surface, contact can be made with a finger or any other pointing device.
Figure 1.1. Resistive touchscreen
1.2 Working
Figure 1.2. Working of Resistive touchscreens
The resistive touchscreens consist of two parallel sheets of resistive coating as mentioned earlier. If no external pressure is applied, then the two sheets are electrically separated. Hence the impedance between the two sheets remains the same.
But when an external pressure is applied, the distance between the two plates is lowered. As a result of this, the impedance between the two sheets is lowered at the touch point.
The top sheet carries a voltage gradient by applying a voltage between the electrodes of the top sheet. Whereas the bottom sheet serves as a slide in a linear potentiometer as shown.
Figure 1.3. Linear Potentiometer
Linear potentiometers are sensors that produce resistance output proportional to the displacement or position. Resistance value changes with the rotation of the screw.
Hence when we apply pressure on the touchscreen, the two sheets touch eachother. When a contact is established between the two sheets, a precise measurement of the touch point is made by first finding the X co-ordinate and then the Y co-ordinate.
1.3 Advantages
It is the product of choice for the manufacturers because it can easily produce a resolution of 4096*4096 DPI or higher.
They are low cost as compared to their ‘active’ counterparts.
This technology can be produced to support multi-touch output.
A sstylus or any pointed object can be utilized to operate such touchscreens.
As its name implies, resistive touchscreens, are widely employed in environments such as hospital laboratories, factories and restaurants because these places contain liquids, chemicals and other contamination that can harm standard screens.
A resistive touchscreen is very rugged and robust.
1.4 Disadvantages
It is highly sensitive to high pressure.
It is highly sensitive to 75% optical transparency.
New tablets are being developed to overcome these deficiencies that can differentiate between a stylus and human finger.
INTRODUCTION :
With the advent of the I-Phone, touch screen technology has reached the mainstream. Every call carrier now offers their own version of touch phones and there have been rumors of completely touch-interfaced computers. While touch screen technology has been around since the 1960’s, the media buzz has taken off in the past two to three years. Touch screen monitors have become more and more commonplace since their prices have dropped in the past decade. Touch screens are found in ATMs, PDAs, cellular phones, grocery checkout counters, airport check-in counters, and many other devices that we use every day.
Simply put, a touch screen is a display that can detect the presence and location of a touch within the display area. The term generally refers to touch or contact to the display of the device by a finger or hand. Touch screens provide an alternative user-interface to the historical mouse and keyboard of traditional computers.
Touch screens first became a research interest in the second half of the 1960’s. In 1971 Samuel Hurst developed the first “touch sensor.” One of the first places where they gained some visibility was in a computer-assisted learning terminal that came out in 1972 as part of the PLATO project. This was the first step in commercializing touch screen technologies. Touch screens became widely used in kiosk and point of sale systems in banks and stores. In 1983, the first touch screen computer, the HP-150, reached the market. Since then we have seen the introduction of advanced touch screen technologies leading to the commercialization of tablet PCs, PDAs, and touch-screen phones.
There are several different types of touch screen technology. The resistive system is based on the use of two parallel conductive and resistive metallic layers. The capacitive system uses a monitor with a built up charge on its surface. When a person touches the surface, the charge is transmitted to the user, thus allowing the computer to recognize the touch. A third technology is the surface acoustic wave. This recognizes touch by using transducers that can analyze at what instance a wave was disturbed.
In this presentation, we will touch on the history behind touch screen technology while also explaining in detail how the different methods of touch screen technologies work. More specifically, we will spend a considerable amount of time describing the different technologies found in devices that use touch screen. We will also delve into the current commercial applications and practical benefits of touch screens. Finally, we will comment on the future applications and potentials of touch screen technology.
HISTORY
The first touchscreen was a capacitive touch screen developed by E.A. Johnson at the Royal Radar Establishment, Malvern, UK. The inventor briefly described his work in a short article published in 1965 and then more fully - along with photographs and diagrams - in an article published in 1967. A description of the applicability of the touch technology for air traffic control was described in an article published in 1968.
Touchscreens first gained some visibility with the invention of the computer-assisted learning terminal, which came out in 1972 as part of the PLATO project. Touchscreens have subsequently become familiar in everyday life. Companies use touchscreens for kiosk systems in retail and tourist settings, point of sale systems, ATMs, and PDAs, where a stylus is sometimes used to manipulate the GUI and to enter data.
From 1979–1985, the Fairlight CMI was a high-end musical sampling and re-synthesis workstation that utilized light pen technology, with which the user could allocate and manipulate sample and synthesis data, as well as access different menus within its OS by touching the screen with the light pen. The later Fairlight series III models used a graphics tablet in place of the light pen.
The HP-150 from 1983 was one of the world's earliest commercial touchscreen computers. Similar to the PLATO IV system, the touch technology used employed Infrared transmitters and receivers mounted around the bezel of its 9" Sony Cathode Ray Tube (CRT), which detected the position of any non- transparent object on the screen.
An early attempt at a handheld game console with touchscreen controls was Sega’s intended successor to the Game Gear, though the device was ultimately shelved and never released due to the expensive cost of touchscreen technology in the early 1990s. Touchscreens would not be popularly used for video games until the release of the Nintendo DS in 2004.
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 is starting to change with the commercialization of multi-touch technology.
The popularity of smartphones, PDAs and tablet computers, portable video game consoles and many types of information appliances is driving the demand and acceptance of common touchscreens, for portable and functional electronics, with a display of a simple smooth surface and direct interaction without any hardware between the user and content, fewer accessories are required.
Touchscreens are popular in hospitality, and in heavy industry, as well as kiosks such as museum displays or room automation where keyboard and mouse systems do not allow a suitably intuitive, rapid, or accurate interaction by the user with the display's content.
Historically, the touchscreen sensor and its accompanying controller-based firmware have been made available by a wide array of after-market system integrators, and not by display, chip, or motherboard manufacturers. Display manufacturers and chip manufacturers worldwide have acknowledged the trend toward acceptance of touchscreens as a highly desirable user interface component and have begun to integrate touchscreen functionality into the fundamental design of their products.
CHAPTER 1 : RESISTIVE TOUCHSCREEN TECHNOLOGY
1.1 Introduction
Resistive touchscreens are touch sensitive computer displays composed of two flexible sheets coated with a resistive material and separated by an air gap or Microdots. The resistive coating is made up of Idium-Tin oxide. It is the most simple technology and hence it is widely used.
When contact is made with the surface of touchscreens, the two sheets are pressed together. On these two sheets there are horizontal and vertical lines that when pushed together, register the precise location of the touch. Because the touchscreen senses input from contact with nearly any object (finger, stylus/pen, palm) resistive touchscreens are a type of "passive" technology.
During the operation of a four-wire touchscreen, a uniform, unidirectional voltage gradient is applied to the first sheet. When the two sheets are pressed together, the second sheet measures the voltage as distance along the first sheet, providing the X coordinate. When this contact coordinate has been acquired, the uniform voltage gradient is applied to the second sheet to ascertain the Y coordinate. These operations occur within a few milliseconds, registering the exact touch location as contact is made.
Resistive touchscreens typically have high resolution (4096 x 4096 DPI or higher), providing accurate touch control. Because the touchscreen responds to pressure on its surface, contact can be made with a finger or any other pointing device.
Figure 1.1. Resistive touchscreen
1.2 Working
Figure 1.2. Working of Resistive touchscreens
The resistive touchscreens consist of two parallel sheets of resistive coating as mentioned earlier. If no external pressure is applied, then the two sheets are electrically separated. Hence the impedance between the two sheets remains the same.
But when an external pressure is applied, the distance between the two plates is lowered. As a result of this, the impedance between the two sheets is lowered at the touch point.
The top sheet carries a voltage gradient by applying a voltage between the electrodes of the top sheet. Whereas the bottom sheet serves as a slide in a linear potentiometer as shown.
Figure 1.3. Linear Potentiometer
Linear potentiometers are sensors that produce resistance output proportional to the displacement or position. Resistance value changes with the rotation of the screw.
Hence when we apply pressure on the touchscreen, the two sheets touch eachother. When a contact is established between the two sheets, a precise measurement of the touch point is made by first finding the X co-ordinate and then the Y co-ordinate.
1.3 Advantages
It is the product of choice for the manufacturers because it can easily produce a resolution of 4096*4096 DPI or higher.
They are low cost as compared to their ‘active’ counterparts.
This technology can be produced to support multi-touch output.
A sstylus or any pointed object can be utilized to operate such touchscreens.
As its name implies, resistive touchscreens, are widely employed in environments such as hospital laboratories, factories and restaurants because these places contain liquids, chemicals and other contamination that can harm standard screens.
A resistive touchscreen is very rugged and robust.
1.4 Disadvantages
It is highly sensitive to high pressure.
It is highly sensitive to 75% optical transparency.
New tablets are being developed to overcome these deficiencies that can differentiate between a stylus and human finger.
