Introduction to the Structure and Function of Capacitive Membrane Switches

Capacitive membrane switch, also known as touch switch, has a wide range of applications, such as medical field, electronic field, industrial field, automotive field, etc. We can see its existence. Let's briefly introduce it.

1. Structure and function of capacitive membrane switch

The combined structure of the capacitive membrane switch is divided into three parts, one is the flexible membrane switch, the other is the capacitive touch screen, and the PCB electronic board, which can be combined to form a complete capacitive switch. Flexible membrane switches are generally made of PET or PC film, because both have good soft properties, the structure of the switch is stable, and the hand feel is good, the main thing is high transparency, which will not affect the user to view the information on the display screen. The working principle of the capacitive touch screen is based on the current induction of the human body. Its structure is a four-layer composite glass screen. The inner surface and the interlayer are each coated with a layer of ITO, and the interlayer ITO coating is used as the working surface. four electrodes. The PCB electronic board plays the main role in the product, connecting the current, connecting the circuit, transmitting the signal, and also controlling the resistance, voltage and current of the product.

2. Requirements for capacitive membrane switch keys

(1) Good appearance: It means that the surface of the film made of the panel is smooth and consistent, and there is no surface defects such as mechanical damage, scratches, inclusions and stains.

(2) Better chemical resistance of the membrane switch: the panel layer may touch different chemicals, but for most common chemicals, such as alcohols, ethers, and mineral oils, it should have a certain resistance ability.

(3) Good weather resistance of the membrane switch: The panel layer is the surface layer of the membrane panel exposed to the natural environment, and the panel material must be able to withstand certain natural environment conditions without deformation, cracking, aging and discoloration.

(4) The dimensional stability of the membrane switch is good: the membrane panel requires that the membrane for making the panel has no significant change in size within a certain temperature range (generally -40 °C ~ 55 °C).

(5) Elasticity requirements: The panel layer is required to have a certain resilience. At the same time, the elastic deformation of the film panel should be small, which can be judged by the elongation rate of the material. Generally speaking, if the elongation rate is large, the amount of elastic deformation is also large, and the resilience performance is poor. .

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