Throughout the past immediate century technology has progressively advanced in many ways. The way to note the level of this change is how persons are interacting with the technology with time. One of these technological advances is the invention of touch screens. A touch screen is an audio visual display that enables its user to control its digital environment through a simple or multi touch gestures using a finger(s) or a simple object such as a stylus and to react to what is displayed and even control how its displayed such as zooming. It has three main components; the touch sensor, controller and obviously a software driver that directs the operating system how to interpret the touch event information that is sent from the controller. The controller is a card that connects between the touch sensor and the device. The touch sensor is a clear glass panel with a touch responsive surface.
The history of touch screens traces back to 1971 with the invention of the Elograph by Elographics, Inc.This company was to produce Graphical data digitizers for use in research and industrial applications. This discovery paved way for further technological advancements. One of the next devices to be invented was the HP-150 touch screen laptop that was built in 1983 by Hewlett Packard. This device had infrared touchscreen capability that led to development of ATM-like applications. These are the two important devices in the development of touchscreens.Over time, touch screens have become increasingly complex and advanced.
Touchscreen technologies have evolved and have differentiated capabilities. Infrared touch screens are based on light-beam interruption technology. 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, causing a drop in the signal received by the photo sensors. Widespread use of the infrared touch screen technology has been hampered by the high cost of the technology and its sensitivity to ambient light. They are only responsive to finger touch and an infrared pen.
Capacitive touch screen technology is recommended for use in applications that require a "finger touch". It will not operate with either a gloved hand or with a mechanical stylus. Capacitive touch screens are curved or flat glass substrates coated with a transparent metal oxide. A voltage is applied to the corners of the overlay creating a minute uniform electric field. A bare finger draws current from each corner of the electric field, creating a voltage drop that is measured to determine touch location.
Resistive touch screens have a flexible top layer and a rigid bottom layer separated by insulating dots, with the inside surface of each layer coated with a transparent conductive coating. Voltage applied to the layers produces a gradient across each layer. Pressing the flexible top sheet creates electrical contact between the resistive layers, essentially closing a switch in the circuit. They respond to anything.
Surface acoustic wave (SAW) technology uses ultrasonic waves that pass over the touch screen panel. When the panel is touched, a portion of the wave is absorbed. This change in the ultrasonic waves registers the position of the touch event and sends this information to the controller for processing. Surface wave touch screen panels can be damaged by outside elements. Contaminants on the surface can also interfere with the functionality of the touch screen. They also have slow response but respond to anything.
Optical touch screen technology uses two line scanning cameras located at the corners of the screen. The cameras track the movement of any object close to the surface by detecting the interruption of an infra-red light source. The light is emitted in a plane across the surface of the screen and can be either active (infra-red LED) or passive (special reflective surfaces).
The popularity of smartphones, tablets, and many types of information appliances is driving the demand and acceptance of common touchscreens for portable and functional electronics. Touchscreens are popular in the medical field and in heavy industry, as well as in kiosks such as museum displays, where keyboard and mouse systems do not allow a rapid, or accurate interaction by the user with the display's content.
Touch screens have several advantages over other pointing devices. A touch screen is intuitive as the user simply touches what he or she sees on the display. A touch screen saves space as no keyboard or mouse is required. Touch screen monitors can even be mounted on walls. Furthermore, touchscreens are the fastest pointing devices available and thus great effort should be made to incorporate them in our daily activities 24/7 365 days a year.
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