Guide: The Membrane Switch sounds quite professional. In fact, the popular one is the panel type Button . This name is familiar. Many equipment control panels use membrane switches, which are widely used in electronic communication, electronic measurement instruments, industrial control, medical Equipment, automotive industry, smart toys, household appliances and other fields. The ancient's cloud: knowing why they know why. The following small series will learn the basic structure and working principle of the membrane Switch with everyone.
1. Membrane Switching Principle - Introduction
The membrane switch is a multi-layer (planar) type (non-locking) button switch composed of a layer of insulating material with certain elasticity, which integrates functions such as buttons, indicating components and instrument panels. The action of the membrane switch is only realized by the vertical movement of the elastic membrane. Although the elastic membrane has been subjected to millions of peristalses and the amplitude of creeping is small, only 0.1-0.3MM, and the rationality of material selection, the film material It can withstand more than one million times of long life without deformation, which determines the durability of the membrane switch.
The membrane switch has beautiful appearance, long service life, simple structure, convenient installation, good hand feeling and small occupied area. It is widely used in all walks of life, from small household appliances to high-tech products, slowly replacing it. The market for some tact switches has a large share in the market.
2. Membrane switch principle - basic structure
In general, the common membrane switch is mainly composed of 6 layers of materials, which are panel, surface glue, upper circuit, isolation layer, lower circuit and primer in the order from the top to the bottom. The following describes the structure of each layer separately:
1) Panel: The panel is the “outer garment” of the entire membrane switch. On the basis of proper arrangement of the buttons, the entire membrane switch plays a necessary decorative role through different colors, patterns and button shapes. The most important function of the panel layer is to use the logo and the button. Therefore, the material must have high transparency, high ink adhesion, high elasticity and anti-folding.
2) Upper circuit and lower circuit: The upper and lower circuits are the electrical components of the membrane switch, and the “off” and “key” of the switch. The performance directly affects the performance of the switchgear, mainly printed on the film. Formed by a layer of conductive material. The upper and lower circuits are responsible for the two electric shock characters necessary for the switch to close. The thickness is generally within the range of 0.05--0.175MM, and the most common is 0.125MM PET.
3) Face glue, insulation layer, primer: The materials of the three-layer structure are double-sided tapes, which have different names due to the different positions in the switch structure. The three-layer double-sided tapes have different thicknesses depending on the layer they are in. This is mainly determined by the thickness of the switch and the operating force of the buttons.
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 a normal state, the upper and lower contacts are in a disconnected state, and the isolation layer isolates the upper and lower lines; when the panel is pressed, the upper panel The contact of the circuit is deformed downward, and the line is re-combined with the lower line to make the line conductive. The line after the conduction is signaled to the externally connected instrument (substrate) to realize its corresponding function; when the finger is released, the upper circuit touches the point bounces back, the circuit is broken, and the loop triggers a signal.
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