The Technology of Touchscreens
Touchscreen technology has been around for over 30 years. This technology can be found in many applications: Industrial Manufacturing, Pharmaceuticals, Medical, Military and Consumer. The first touchscreen, introduced in 1972, was a terminal of a computer-assisted learning terminal for the PLATO Project; this project, originally created for the University of Illinois, expanded across the globe. The common definition of a touchscreen is a display that detects the presence and location of a touch within the display area however, there are five different types of technology for touchscreens.
The resistive touchscreen uses a glass panel overlay with a uniform resistive coating. A polyester coversheet is tightly suspended over the top of the glass, separated by small, transparent insulating dots. The coversheet has a hard durable coating on the outer side and a conductive coating on the inner side. When the screen is touched, the conductive coating makes electrical contact with the coating on the glass. The voltages produced are the analog representation of the position touched. The controller digitizes these voltages and transmits them to the computer for processing. The resistive touchscreen is the most commonly used and popular touchscreen technology. This display is widely used in Grocery and Retail Stores, Restaurants, Hotels, Industrial Applications (HMI--Human Machine Interface) on manufacturer plant floors and Control Rooms, Medical and Pharmaceutical facilities, and some Military applications.
The Capacitive touchscreen consists of an insulator, such as glass, coated with a transparent conductor, such as indium tin oxide. The human hand is also a conductor; touching the surface of the screen results in a distortion of the local electrostatic field, measurable as a change in capacitance. This change in frequency of the wires at that particular point causes the position to be calculated and identified by the controller. The controller then outputs the x-y touch coordinate via a Serial or USB communication link. In most applications, a polyester anti-glare overlay is bonded to the outer surface to ensure that any breakage is contained in order to meet the requirements for food manufacturing and some pharmaceutical manufacturing. The Capacitive touchscreen is more durable and resistant to scratching. Gloves will not work with the standard Capacitive touchscreen, only human fingers can be used with this technology.
The Projected Capacitive touchscreen is similar to the Capacitive touchscreen but is more rugged. It uses a capacitive field that works through 4mm of thermally toughened glass. This not only protects the sensitive electronics from exposure to the harsh environment outside of the enclosure, but unlike other capacitive touchscreens, it will operate through many types of gloves. The electronic controller effectively divides the screen into sensing cells using micro-fine wires that are embedded into the outer glass, which is thermally toughened to withstand impact. These wires are connected to the touchscreen controller circuitry, and an oscillation frequency is established for each wire. Touching the glass causes a change in frequency of the wires at that particular point and the position is calculated and identified by the controller. The controller then outputs the x-y touch coordinate via a Serial or USB communication link. In most applications, a polyester anti-glare overlay is bonded to the outer surface to ensure that any breakage is contained in order to meet the requirements for food manufacturing and some pharmaceutical manufacturing. The Projected Capacitive touchscreen is the most durable and vandal-proof technology. This new technology is becoming more popular and more widely used in more rugged X purged, Z purged, or Non-Incendive manufacturer areas.
The SAW Touchscreen has a glass overlay with a grid of transmitting and receiving piezoelectric transducers. The touchscreen controller sends a 5 MHz electrical signal to the transmitting transducer, which converts the signal into ultrasonic waves within the glass. When the screen is touched, a portion of the wave traveling across it is absorbed, thus changing the received signal. The signal is then compared to a stored reference signal, the change is recognized, and a coordinate calculated. The process happens independently for both the X and Y-axes. By measuring the amount of the signal that is absorbed, a Z-axis is determined. SAW Touchscreens have the best optical clarity but are more sensitive to outside elements, which can damage them. Contaminants on the surface can also interfere with the functionality of the touchscreen; therefore, the SAW technology is more suitable for indoor use but cannot withstand wash downs. Due to their durability and glass base material, this display is ideal for applications in both public and industrial settings like mall kiosks, touchscreen monitors for ATM machines, and Industrial Control Rooms.
The Infrared (IR) Touchscreen relies on the interruption of an IR light grid in front of the display screen. Integrated into the display bezel is an opto-matrix frame that contains a row of IR-light emitting diodes (LEDs) and phototransistors, each mounted on two opposite sides to create a grid of invisible IR light. The opto-matrix frame is isolated from the outside environment by an IR transparent barrier. The IR controller sequentially pulses the LEDs to create a grid of IR light beams. When a stylus, such as a finger, enters the grid, it obstructs the beams. One or more of the phototransistors detects the absence of light and transmits a signal that is the X and Y coordinates. Because the infrared scanning is done in front of the display, a bulletproof, 3/8" thick polycarbonate window is installed between the IR grid and the display itself. This window provides a level of environmental protection for the electronics that is unique to the infrared touchscreen technology. Infrared touchscreens are suitable for applications in areas of extreme abuse, mostly found on the manufacturer plant floor where there are multiple users. In addition, for area where gloves are used the Infrared touchscreen is a good fit. Like the SAW technology, the Infrared Touchscreen is also not good in wash down environment but can be in purged areas.
In conclusion, there is a touchscreen for any area within the Industrial or Consumer platform. In this comparison chart supplied by Strongarm, Inc., you can get a better view as a whole of which touchscreen perform the best in certain scenarios.
For more information on touchscreen technology or assistance with selecting the touchscreen for your industrial application please contact Lesia Bell your I2 Inside Sales coordinator at 443.683.8031 or lbell@insourcess.com.
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The Technology of Touchscreens
Touchscreen technology has been around for over 30 years. This technology can be found in many applications: Industrial Manufacturing, Pharmaceuticals, Medical, Military and Consumer. The first touchscreen, introduced in 1972, was a terminal of a computer-assisted learning terminal for the PLATO Project; this project, originally created for the University of Illinois, expanded across the globe. The common definition of a touchscreen is a display that detects the presence and location of a touch within the display area however, there are five different types of technology for touchscreens.
The resistive touchscreen uses a glass panel overlay with a uniform resistive coating. A polyester coversheet is tightly suspended over the top of the glass, separated by small, transparent insulating dots. The coversheet has a hard durable coating on the outer side and a conductive coating on the inner side. When the screen is touched, the conductive coating makes electrical contact with the coating on the glass. The voltages produced are the analog representation of the position touched. The controller digitizes these voltages and transmits them to the computer for processing. The resistive touchscreen is the most commonly used and popular touchscreen technology. This display is widely used in Grocery and Retail Stores, Restaurants, Hotels, Industrial Applications (HMI--Human Machine Interface) on manufacturer plant floors and Control Rooms, Medical and Pharmaceutical facilities, and some Military applications.
The Capacitive touchscreen consists of an insulator, such as glass, coated with a transparent conductor, such as indium tin oxide. The human hand is also a conductor; touching the surface of the screen results in a distortion of the local electrostatic field, measurable as a change in capacitance. This change in frequency of the wires at that particular point causes the position to be calculated and identified by the controller. The controller then outputs the x-y touch coordinate via a Serial or USB communication link. In most applications, a polyester anti-glare overlay is bonded to the outer surface to ensure that any breakage is contained in order to meet the requirements for food manufacturing and some pharmaceutical manufacturing. The Capacitive touchscreen is more durable and resistant to scratching. Gloves will not work with the standard Capacitive touchscreen, only human fingers can be used with this technology.
The Projected Capacitive touchscreen is similar to the Capacitive touchscreen but is more rugged. It uses a capacitive field that works through 4mm of thermally toughened glass. This not only protects the sensitive electronics from exposure to the harsh environment outside of the enclosure, but unlike other capacitive touchscreens, it will operate through many types of gloves. The electronic controller effectively divides the screen into sensing cells using micro-fine wires that are embedded into the outer glass, which is thermally toughened to withstand impact. These wires are connected to the touchscreen controller circuitry, and an oscillation frequency is established for each wire. Touching the glass causes a change in frequency of the wires at that particular point and the position is calculated and identified by the controller. The controller then outputs the x-y touch coordinate via a Serial or USB communication link. In most applications, a polyester anti-glare overlay is bonded to the outer surface to ensure that any breakage is contained in order to meet the requirements for food manufacturing and some pharmaceutical manufacturing. The Projected Capacitive touchscreen is the most durable and vandal-proof technology. This new technology is becoming more popular and more widely used in more rugged X purged, Z purged, or Non-Incendive manufacturer areas.
The SAW Touchscreen has a glass overlay with a grid of transmitting and receiving piezoelectric transducers. The touchscreen controller sends a 5 MHz electrical signal to the transmitting transducer, which converts the signal into ultrasonic waves within the glass. When the screen is touched, a portion of the wave traveling across it is absorbed, thus changing the received signal. The signal is then compared to a stored reference signal, the change is recognized, and a coordinate calculated. The process happens independently for both the X and Y-axes. By measuring the amount of the signal that is absorbed, a Z-axis is determined. SAW Touchscreens have the best optical clarity but are more sensitive to outside elements, which can damage them. Contaminants on the surface can also interfere with the functionality of the touchscreen; therefore, the SAW technology is more suitable for indoor use but cannot withstand wash downs. Due to their durability and glass base material, this display is ideal for applications in both public and industrial settings like mall kiosks, touchscreen monitors for ATM machines, and Industrial Control Rooms.
The Infrared (IR) Touchscreen relies on the interruption of an IR light grid in front of the display screen. Integrated into the display bezel is an opto-matrix frame that contains a row of IR-light emitting diodes (LEDs) and phototransistors, each mounted on two opposite sides to create a grid of invisible IR light. The opto-matrix frame is isolated from the outside environment by an IR transparent barrier. The IR controller sequentially pulses the LEDs to create a grid of IR light beams. When a stylus, such as a finger, enters the grid, it obstructs the beams. One or more of the phototransistors detects the absence of light and transmits a signal that is the X and Y coordinates. Because the infrared scanning is done in front of the display, a bulletproof, 3/8" thick polycarbonate window is installed between the IR grid and the display itself. This window provides a level of environmental protection for the electronics that is unique to the infrared touchscreen technology. Infrared touchscreens are suitable for applications in areas of extreme abuse, mostly found on the manufacturer plant floor where there are multiple users. In addition, for area where gloves are used the Infrared touchscreen is a good fit. Like the SAW technology, the Infrared Touchscreen is also not good in wash down environment but can be in purged areas.
In conclusion, there is a touchscreen for any area within the Industrial or Consumer platform. In this comparison chart supplied by Strongarm, Inc., you can get a better view as a whole of which touchscreen perform the best in certain scenarios.
For more information on touchscreen technology or assistance with selecting the touchscreen for your industrial application please contact Lesia Bell your I2 Inside Sales coordinator at 443.683.8031 or lbell@insourcess.com.
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