CSI Capacitive Switch Solutions

What are Capacitive Switches?

A capacitive switch is a type of touch-controlled electrical switch that operates by measuring change in capacitance. It works in the same manner as a typical capacitive smartphone: when you touch the surface, a small electrical charge is transferred from your body to the switch, which subsequently causes a change in capacitance. The switch detects this change, responding with the appropriate command.

Upon touching a capacitive switch, this electrical charge disturbs the switch’s own electrical charge; thus, causing a change in capacitance. Because of this change, the switch can identify when and where the touch occurred.

Capacitive Switch Construction:

A capacitive switch consists of three main layers, the graphic overlay, the circuit, and the backer:

  • The overlay consists of the graphic artwork and can also include windows, embossing, coatings, adhesives, and selective texturing.
  • The circuit switch will either be a Flexible Printed Circuit or a Printed Circuit Board.
  • The backer is the final part of the capacitive switch, and may or may not include an adhesive that must bond to your specific substrate. The most common materials used for overlays are plastic, acrylic, and glass due to their durability and versatility.  

CSI Keyboards Capacitive Switches

Advantages of the Capacitive Switch Technology:

There are no mechanical components in a capacitive switch, resulting in a longer lifespan when compared to their mechanical counterpart. Additionally, capacitive switches can withstand some of the harshest environments, including outdoor environments. If the intrusion of dirt, dust or moisture is a concern, capacitive is probably the best option for an electrical switch.

The key thing to remember about capacitive switches is that they require direct contact with a conductive object to operate. This is why using a stylus typically won’t work (unless it’s a capacitive stylus).

Capacitive switches can also be used in a wide range of applications, including vending machines, smartphones, tablets, human machine interfaces (HMIs), industrial controls, appliances, infotainment centers and more. Furthermore, they support integration of other features like light-emitting diode (LED) backlights.

Capacitive Switch Backlighting:

If you would like to backlight your application, the capacitive switch construction would incorporate either light guide film or LEDs for uniform lighting. Other options for backlighting are fiber optic backlighting and EL backlighting. Depending on the requirements of your application such as thickness preference, shape, environmental exposure, and other unique specifications, the backlighting options would vary and be selected specifically to fit the function of your device. Using the latest LED powered lighting can reduce cost and reduce power used by a device. 

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