Membrane switch on the buttons to color different said the position, shape and size of the key body, in the initial stages of membrane switch is relatively common. Three-dimensional membrane switch: usually, the buttons on the membrane switch only express the position of the key body in color, shape and size. Only in this way, the plane membrane switch by the operator of the vision to identify the accuracy of the operation, in the absence of appropriate feedback shows that finger is pressing the button in the effective scope of switch action, and thus affect the self-confidence and operating speed of the machine monitoring. An open the key body slightly raised, slightly higher than the panel, constitute a three-dimensional shape of membrane switch, called a three-dimensional key switch. Three-dimensional key can not only accurately given the range of the key body, improve the recognition rate.