Basic principle of membrane switch panel

1. Principle of membrane switch - Introduction

Membrane switch is a multi-layer structure (plane) type (non lock) key switch composed of a certain elastic insulating material layer, which integrates the functions of key, indicating element, instrument panel and so on. The action of the membrane switch is only realized by the elastic membrane bouncing in the vertical direction. Although the elastic membrane has undergone millions of times of peristalsis, Adhesive Tape and the amplitude of peristalsis is very small, only 0.1-0.3mm. In addition, due to the rationality of material selection, the membrane material can withstand more than one million times of large service time without deformation, which determines the durability of the membrane switch.

Membrane switch has the characteristics of beautiful appearance, long service time, simple structure, convenient installation, good hand feeling and small occupied area. It is widely used in all walks of life, from household appliances to high-tech products. It slowly replaces some light touch switch markets and occupies a great share in the market.

2. Membrane switch principle - basic structure

Generally speaking, common membrane switches are mainly composed of six layers of materials, which are panel, surface glue, upper circuit, isolation layer, lower circuit and bottom glue in the order from table to inside. The following describes the structure of each layer:

(1) Panel: the panel is the "coat" of the whole membrane switch. On the basis of properly arranging the keys, it plays a necessary decorative role on the whole membrane switch through different colors, patterns and key shapes. The panel layer Zui is mainly used to mark and press keys, so the selected materials must have the characteristics of high transparency, high ink adhesion, high elasticity, anti folding, etc.

(2) Upper circuit and lower circuit: the upper circuit and lower circuit are the electrical components of the film switch and the "off" and "key" of the switch. Their performance directly affects the performance of the switch, which is mainly formed by printing a layer of conductive material on the film. The upper and lower circuits play the two necessary roles of electric shock for switch closing, and their thickness is generally within 0.05-0.175mm, Zui commonly 0.125mmpet.

(3) Surface Adhesive Tape, isolation layer and primer: the materials of these three layers are double-sided Adhesive Tape, which have different names due to their different positions in the switch structure. The three layers of double-sided tape have different thicknesses according to their respective layers. This is mainly determined by the thickness of the switch and the Cao force of the key.

3. Membrane switch principle - working principle

The basic working principle of the membrane switch is as follows: when the panel is not pressed, the membrane switch is in the normal state, its upper and lower contacts are disconnected, and the isolation layer isolates the upper and lower lines; When the panel is pressed, the contact of the upper circuit deforms downward, coincides with the lower circuit and turns on the circuit. The turned on circuit sends a signal to the external connecting instrument (substrate), so as to realize its corresponding function; When the finger is released, the upper circuit contact bounces back, the circuit is disconnected, and the circuit triggers a signal.