Touch Screen

Touchscreen is an electronic device that has a dual function, namely as output and as input.

How it works
It translates the received touch on the screen surface into position coordinates on the screen, then execute certain commands corresponding to the image on the screen is touched. Actually it is not the image that triggered the execution of the command, but the coordinates of touch that trigger execution of commands.

Type of Touchscreen

• Resistive screen. Resistive screen is coated by a thin layer of metallic conductive and resistive to electrical signals. Conductive layer is a layer that is easy to conduct electrical signals, whereas the resistive layer is a layer that holds an electrical current. These two layers are separated by a transparent divider spots, so that this layer must be separated from each other in a normal state. In the conductive layer is also flowing electric current that served as the reference current. When both layers touch, it will be forced to directly contact each other physically. Because of the contact between the conductive and resistive layers there will be a disruption in the electrical current references. The effects of these disorders on the conductive layer is going to change electrical currents, then reported to the controller for further processing again. Information of this touch mathematically processed by the controller to produce an accurate position and coordinates of the touch. Then the information is integrated with other programs so that it becomes an application that is easy to use.

• Capacitive screen. The capacitive system has a capacitive wrapper layer on the entire surface. Touchscreen panel is equipped with a wrapping layer made from indium tinoxide that can pass electrical current continuously and then directed to the sensor. This layer utilize the capacitive nature of the hand or the human body. When the layers are in a normal state (without any touch of the hand), the sensor will be given a value of electric current is used as reference. When your fingers touch the surface of this layer, the reference value is changed because there are electrical currents that change the entry into the sensor. Information from these events in the form of electric current will be received by the sensor. It will be forwarded to a controller. Position calculation process will begin here. This calculation uses the position of the four corner points on a touchscreen panel as a reference. When the result of the calculation is obtained, then the position and coordinates of the touch can be known well.

• Surface Acoustic Wave. The touchscreen technology utilizes ultrasonic waves to detect events on the surface of the screen. At the touchscreen monitor, there are two transducers, ultrasonic signal transmitter and receiver. Also equipped with a reflector which serves as a deterrent so that ultrasonic waves remain on the monitor screen area. Both transducers are installed in all four sides, two vertical and two horizontal. When the panel is touched to its touchscreen, no part of the wave is absorbed by that touch, such as hindered by hand, stylus, keys, and more. That touch has made changes in the transmitted waveform. Changes in ultrasonic waves that occur is received by the receiver and translated into electrical pulses. This information touches turn into a form of data that will be forwarded to the controller for further processing.

• Infrared Touchscreen. Infrared Touchscreen has a series of IR Leds which form the array X axis, Y axis , and a photo-detector (light detectors). Photo detector will detect any changes in the pattern of light emitted by the Leds each time the user touches the monitor / screen.