Strand 3: IT Systems

3.1 Hardware

Input Devices

Touch Sevsitive Devices

Touch sensitive devices are any device that needs an input driven by a user pressing the device. The first one many will think of are touchpads but keyboards are touch sensitve devices too. A simple list of touch sensitve device are keyboards, touchpads,

Touchpad devices use a touchpad, hence the name or otherwise know as a track pad. Touchpads are a type of pointer device, like a mouse, they allow a user to control a pointer on a screen. But unlike mice touchpads are controlled by using a finger (sometimes a stylus can be used, though this depends on the type of touchpad). Touchpads allow for a smother experience when using a device as there is no pressing of buttons and allow for a unique navigation, as with Apple’s iPods with the ‘click wheel’ or their iPod Touch where the whole screen is interactive through touch.

The two main types of touchpads are capacitance and conductance.

Conductance Touchpads:

Conductance Touchpads work by having two grids of wire with a current through them and a thin insulator between them. When the thouchpad is pressed on the grids get closer and the insulator gets thiner to the piont where the grids can pass a electrical current. Where the grid connects, the computer can calculate position or movement These types of touchpads are pressure based and so a stylus or any other object can be used.

Capacitance Touchpads:
capacitance touchpad
capacitance touchpad

The Capacitance Touchpads also work with wires. One layer has horizontal arangment of wires, and another has a them aranged verticaly. the diference though is that it dosen't work though pressure. the wires hold a electrical charge and when an object like a finger that has capacitance it disrupts the charge in the wires and the computer puts it together by using coordinates, one layer is a y value and another an x value. Because it works via capacitance only objects with a larger sufface area, and density similar to your finger will work, normal stylus don't work.