Touch screen technology plays an important role in our modern life. It is the direct manipulation gesture based technology. Without useing the command-line-commands, you can manipulate digital world inside a screen. Well, the touch screen is also an electronic visual display capable of detecting and effectively locating a touch over its display area. Well, the touch screen is sensitive to the touch of a human finger, hand, pointed finger nail and passive objects like stylus.
There are different kinds of touch screens, like resistive touchscreen, capacitive touch screen, surface accounts wave, infrared. Taking the resistive touch screen technology for an example, it consists of flexible top layer made of PET and rigid bottom layer made of glass. Both layers are coated with a conducting compound called ITO and spaced with spacers. The electricity current will flow between the two layers while the monitor is operational. When you touch the screen, the screen presses down and touches the bottom layer.
The 4-wire resistive touchscreen calculates the axes information of the touch by using both the layer. Touch measurement in the 4-wire is a process that contains two steps, the x-coordinate and y-coordinate. The x-coordinate of the touch point is calculated by creating a voltage gradient on the flexible layer and the y-coordinate can be calculated by creating a voltage gradient along the bottom layer.
The position sensing of 5-wire resistive touchscreen is on the stable glass layer. One wire goes to the coversheet and 4 wires are deployed to the 4 corners of the bottom sheet. The function of the coversheet is to act as voltage measuring probe. The 8-wire resistive touchscreen is just a variation of the 4-wire one with the addition of 4 sense wires, 2 for each layer. The main function of the sensing point is to reduce the environmental drift to increase the stability of the system.
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