Traditional keypads and user interface are being replaced with compact and thin alternatives known as a membrane keypad. These keypads are made with multiple layers of thin plastic or other flexible materials. The topmost layer has the GUI or keys. The common components of a membrane keypad are–
Overlay- It is the topmost layer that has the Graphics User Interface. Though pictures or keys printed on the overlay, users understand how to operate the appliance. The overlay is usually designed through screen printing ink or digital printing on the front side or reverse side of the plastic.
Spacer top adhesive- It lies under the graphic overlay and joins the graphic layer to the other layers of the keypad.
Dome retainer- it holds the metal or plastic domes in place. When domes are pressed it provide the tactile feeling.
Spacer- This layer lies under the dome retainer. It contains ventilation cuts and allows air circulation when tactile membrane keypad gets activated. Spacer demarcates the top and bottom circuits.
Circuit layer- it is the electrical circuit that is printed on the flexible PED. The most frequent inks used for printing the circuit are silver and carbon inks.When the user presses down the dome or the pad on the membrane keypad, the circuit closes and current starts flowing and thus work is done accordingly.
What is a backlit membrane keypad?
It is a membrane keypad that is incorporated as an internal lawyer allowing light to travel across the membrane keypad. While users can use this keypad in darker environment or at night, the tactile feel of these keypads is not lost thus users can get improved feeling of touch as the buttons or domes come back to their original positions after pressing. Backlighting of keypads makes the displays and legends more readable. There are different types of backlighting techniques to choose from.
Light Guide Film or LGF- This technology is used in membrane keypads that need thin profile. In LGF technology, a thin film absorbs light and this light is spread across the keypad through side-firing or right-angle LEDs. LGF can be made into any size and shape. LGF is more expensive than other backlighting technologies.
Light Emitting Diodes or LED- These are low-cost lighting techniques. They are reliable and offer efficient power usage. LEDs offer backlighting in different colors, intensities and lamp sizes.
Fiber Optic Lighting- In this backlighting technology, two-three layers of fiber optic cloth is used. This woven cloth layer is used to create rectangular shaped light emitting space. Fiber optic technology is affordable and ensures uniform brightness. They do not produce electromagnetic interference or emit heat. For more information visit here: CSI Keyboards, Inc.