A Touch Screen is a display which 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 . Touchscreen can also sense other passive objects, such as a stylus. The ability to interact directly with a display typically indicates the presence of a touchscreen.
The touch screen has two main attributes. First, it enables you to interact with what is displayed directly on the screen, where it is displayed, rather than indirectly with a mouse or touch pad. Secondly, it lets one do so without requiring any intermediate device, again, such as a stylus that needs to be held in the hand. Such displays can be attached to computers or, as terminals, to networks. They also play a prominent role in the design of digital appliances such as the personal digital assistant (PDA), satellite navigation devices and mobile phones.
Compatible O/S: Win 98, Win 95, Win 3.x, DOS, NT, Macintosh, Amiga, Linux, OS/2, XP, etc.
Touch Screen Technologies:
- Acoustic Wave Touch Screen Technology:
Acoustic wave touch screens use transducers mounted at the edge of a glass overlay to emit ultrasonic sound waves along two sides. These waves are reflected across the surface of the glass and received by sensors. A finger or other soft tipped stylus absorbs some of the acoustic energy and the controller measures the amplitude change of the wave to determine touch location.
There are three variants of Acoustic, Surface Acoustic Wave (SAW) and Guided Acoustic Wave (GAW) and Acoustic Pulse Recognition (APR).
Applications: Restaurant and hospitality automation, Retail Point-of-Sale (POS) terminals, Pharmacy automation, Industrial automation, Office automation. - Infrared Touch Screen Technology:
Infrared touch screens are based on light beam interruption technology. Instead of an overlay on the surface, a frame surrounds the display. The frame has light sources, or light emitting diodes (LEDs) on one side and light detectors on the opposite side, creating an optical grid across the screen. When an object touches the screen, the invisible light beam is interrupted. The input method is Finger or gloved hand activation.
Since the infrared beams are a little in front of the display, touch is activated even before the user actually touches the display, causing parallax errors.
Applications: Food processing, Industrial automation, Medical equipment, In vehicle and transportation, Point-of-sale (POS) terminals. - 4 Wire Resistive Touch Screens:
Touch measurement in 4 Wire technology is a 2 step process. First, the distance along the x axis at the point of touch is measured by creating a horizontal voltage gradient on the top sheet, with the bottom acting as the return layer. Second a vertical voltage gradient is created on the bottom layer, to measure the y axis.
The technology and electronics are simple, making 4 wire the cheapest touchscreen technology. But since the voltage gradient is needed on both the layers, any damage to either layer causes the touchscreen to stop functioning. And damage is easy, since often both layers are plastic. The input method is finger, gloved hand, or stylus activation.
Applications: Portable devices, Office automation, Light industrial automation, Medical equipment, Consumer products. - 5 Wire Resistive Touch Screens:
In 5 Wire resistive, the main electronics are on the glass bottom layer. A uniform voltage is applied to the top plastic layer. A touch causes an electrical contact between the top and bottom layers. Depending on the point of touch the voltages at the 4 corners of the glass are different — these are measured, and used by a complex algorithm in the controller to calculate the x - y coordinate of the point of touch. The input method is finger, gloved hand, or stylus activation.
Applications: Point-of-sale (POS) terminals, Voting machines, Industrial automation, Medical equipment, Office automation, Retail automation, Pharmacy automation. - Capacitive Touch Screen Technology:
A capacitive touchscreen panel is coated with a material, typically indium tin oxide, that conducts a continuous electrical current across the sensor. The sensor therefore exhibits a precisely controlled field of stored electrons in both the horizontal and vertical axes - it achieves capacitance. Capacitive sensors work based on proximity, and do not have to be directly touched to be triggered. The input method is only finger contact and will not work with a gloved hand or pen stylus. It is a durable technology. Capacitive touch screens can also support multi touch. A good example of this is Apple Inc's iPhone and iPod touch.
Applications: Public access, Gaming machines, Point of Sale (POS), Kiosks, ATM, Industrial controls.
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3M Microtouch Touch Screen Technology:
- Surface Capacitive:
Surface capacitive touch technology is one of the most established touch interfaces available today. Surface capacitive technology is the preferred solution for public-access applications in contaminant-prone environments.
- ClearTek II: ClearTek II touch sensors offer a high-endurance solution that is unaffected by on-screen contaminants such as chemicals, grease, dirt, and water. This makes it ideal for touch applications where exceptional performance, vibrant optics and environmental robustness is required every time.
- Touch Pen: Touch Pen System extends the input flexibility by supporting both finger touch and pen input. The Touch Pen stylus offers handwriting recognition, signature capture, and on-screen annotation capabilities. It is an excellent solution for applications with dense menus or with detailed images too small to touch with a finger.
The Touch Pen system can be set up in dual mode (pen or finger touch input) or pen-only mode. In dual mode, the touch screen accepts touch from both the pen or from a user’s finger, which is critical for most point-of-sale signature capture applications. In pen mode, only pen input is accepted and all other input, including a hand resting on the screen called "palm rejection", is ignored. - Tough Touch: Tough Touch II capacitive touch systems are an ideal solution for ruggedized self-service kiosks and ATM applications environments where impact strength, shatter resistance, superior surface wear, and viewer privacy are a requirement.
Tough Touch II is most rugged capacitive touch product and its construction combines a Micro Touch ClearTek II capacitive touch sensor with a backer glass layer optically laminated to the back. This laminated construction makes Tough Touch II is an ideal touch solution for unsupervised, vandal-prone environments.
- Bending Wave:
Dispersive Signal Technology is proprietary implementation of bending wave technology enhanced to optimize real-time touch response for large-screen public-access applications.
Dispersive Signal Technology’s theory of operation is based on piezos, mounted in each corner of the glass sensors, collecting and converting the bending wave energy created by a touch into digital signals that are processed by proprietary algorithms residing in the touch controller.
- Dispersive Signal Technology (DST): DST touch systems offer a chemically-strengthened glass, stylus-independent touch solution with fast-accurate-repeatable response and operation unaffected by contaminants, static objects or other touches on the screen. DST is ideal for large-format LCD displays used for interactive digital signage and point-of-information applications.
DST is poised to become the touch technology standard for large-format interactive displays. Traditional touch technologies detect "touch" by interrupting acoustic waves, optical fields or infrared light above the surface of the touch screen. One advantage of DST is that it precisely calculates touch locations by analyzing the bending waves within the glass substrate that are created by the user’s touch. This allows for fast, accurate, reliable touch performance that is unaffected by contaminants, scratches, or static objects on the screen, as well as enabling stylus support and multi-user capability.
- Dispersive Signal Technology (DST): DST touch systems offer a chemically-strengthened glass, stylus-independent touch solution with fast-accurate-repeatable response and operation unaffected by contaminants, static objects or other touches on the screen. DST is ideal for large-format LCD displays used for interactive digital signage and point-of-information applications.
- Tactile Feedback:
Tactile feedback technology provides touch screen users with the "sensation" that they are actually depressing traditional mechanical buttons. The tactile feedback effect is created when the user simultaneously sees a video button depress, hears an audio file of the mechanical "click" and feels a vibration in the touch screen’s glass surface. The user instinctively interprets the combination of these three sensations as depressing a mechanical button, when actually they’re touching a solid glass surface.
- Capacitive Touch Sense: The Capacitive Touch Sense system provides tactile feedback effects for on-screen, video buttons so users actually "feel" like they are depressing mechanical buttons. The system consists of an enhanced ClearTek II touch sensor, a hybrid EX II touch and tactile feedback controller, and two or more screen actuators depending on screen size.