Enhancing Effectiveness of Membrane Keypad by Backlighting

Membrane Keypad Backlighting - Linepro Controls Pvt Ltd

A backlit membrane keypad is a membrane switch incorporated as an internal layer that allows light to travel across the keypad areas without losing the keypad’s tactile feel on the user.

In tactile feel, there is improved feeling of touch and the feel is perceived with clarity due to the button pops back up after pressing. This feature is not incorporated in non-tactile switches. Know more about the difference between tactile and non-tactile feedback systems in customized input devices!

Linepro is leading the way in providing backlit membrane keypads and rubber keypad or silicon keypad assemblies. Our Engineering and Design Engineers have been working with our component and material suppliers to create keypads that are visually attractive and strategically visible. We are always focused on creating fully backlit membrane keypads by keeping it’s thin profile intact. It is now possible to provide cost effective backlit keypads, icons and logos. They can be multi-colored and are able to light together or separately.

What are the Backlighting Options for Membrane Keypads?

One way to improve user experience and distinguish your product from others is to include backlighting in the design of the membrane keypads. Backlighting of membrane keypad is the process of strategically incorporating lights inside the structure of the keypads to make the keypads as well as legends and displays more readable. There are certain aesthetic and cost benefits and drawbacks to consider depending on the type of backlighting technique used. Linepro can help you choose the most efficient method of backlighting for your user interface, and provides a full variety of backlighting techniques that include:

Light Guide Film (LGF)

Light Emitting Diodes (LED)

Electroluminescent (EL) Lighting

Fiber Optic Lighting

Linepro also offers other backlighting membrane keypad options, such as a dead-front section that has icons that are not visible until they are lit. Read on to find out more about these technologies and the options.

Light Guide Film (LGF)

Membrane Keypad Backlighting using Light Guide Film - Linepro Controls Pvt Ltd
Light Guide Film used as backlighting media in Membrane Keypad requiring thin profile

Light Guide Film (LGF) is a light-absorbing thin film technology that can direct light generated through right-angle or side-firing LEDs over the space that must be illuminated.

The benefit that comes with LGF is that it can be made into nearly any shape and size, offering uniform backlighting of the membrane keypad across several areas.

Numerous LGF film can be employed in a single application to provide separate backlighting to various graphic elements.

Different colors of LEDs can be used to create distinctive lighting effects. White LEDs can be used to illuminate various printed images onto the overlay.

While Light Guide Film can be more costly than other backlighting technology however, it comes with many advantages:

  • It is that the LGF can be extremely thin, which means, it is possible to be integrated in membrane keypads which cannot be permitted to exceed a certain amount of thickness (i.e. small, lighter devices)
  • LGF has a minimal impact on the tactile feel of buttons.
  • LGF can offer backlighting that is even across smaller areas, and even in instances where the light remains ON while the switch is powered ON.

Light Emitting Diodes (LED)

Membrane Keypad Backlighting using Light Emitting Diodes (LED) - Linepro Controls Pvt Ltd
LED implanted beneath the Graphic overlay of Membrane Keypad

LEDs or light emitting diodes are used predominantly as indicator lights; they are well-known as point-source, low-cost lighting technique. LEDs that are embedded emit very little heat and are available in a range of colors, including red blue, green, yellow white, as well as bi-color lamp packs. Different intensities are offered with some specifically designed to be used in outdoor settings.

Surface mount LEDs are integrated with the switch structures made of polyester which offer a reliable and economical lighting source. A wider selection of lamp designs is available for PCB Membrane Switches as well as Copper Flex membrane keypads and they can also be soldered through holes to increase the durability.

Other advantages of LED backlighting are:

  • Long life and reliability usually more than 100,000 hours
  • Low cost
  • Power consumption is efficient, and it can operate with low voltages
  • Available in a range of intensities, colors, and lamp sizes

Electroluminescent Lamp (EL)

Electroluminescent lamps have phosphor that converts electrical power directly to light. Because Electroluminescence is efficient, conversion results in low energy consumption as well as losses caused by the emission of heat or IR emissions are less. EL backlighting systems therefore use very little power during normal use. They are ideal for applications with low or no light in which the backlight isn’t always ON because the phosphor can degrade when used for extended periods in high frequencies and voltages. The lifespan of the EL lamp depends on the quality of the Phosphor used and how frequently the lamp is driven.

Additional characteristics and design considerations for EL lamps include:

  • EL lamps draw very little energy
  • It provides uniform, evenly-balanced backlighting  of the membrane keypads across the entire area of the
  • Requires DC to AC converter for operation
  • A thin profile and long-lasting design make it suitable for the majority membrane switch designs.
  • Only a limited color options are available

Fiber Optic Lighting

Membrane Keypad Backlighting using Fiber Optics - Linepro Controls Pvt Ltd
Fiber Optic being used for backlighting membrane keypad

The typical fiber-optic lamp comprises of two to three layers of woven fiber optic cloth, which is then used to create a rectangular light-emitting region. The fibers emerging from the other end are then wrapped into a circular ferrule, and connected together with one or several LED lights. Fiber optic lamps are an affordable method of achieving better uniformity of backlighting over larger areas of the membrane keypad. Fiber optic backlighting ensures that, light usually from an LED as source, is evenly distributed over the graphic overlay by using extremely thin fibers of plastic. 

Additional aspects and design factors of fiber optic lighting include:

  • Longer lifespan compared to LED lamps, which typically last 100,000 hours, based on an average LED
  • Low power requirement of 20-50 mA when using an LED
  • Uniform brightness to backlight large membrane keypad backgrounds
  • Fiber optic lamps don’t emit heat or produce electromagnetic interference
  • Can withstand extreme temperatures and high humidity

Backlit membrane keypads can provide advantages to the final product, which includes:

  • Enhancing the visibility of users when the product is used in a dimly or darkly lit surroundings
  • Making keys and inputs easier to locate and read
  • Drawing attention to a specific location, for example, light indicators on a panel
  • Modernizing appearances of the equipment by giving them an aesthetic style
  • Making accessibility of products easier to those with disabilities.

There are varieties of methods that can be used to produce the desired backlight effects in membrane keypads based on power requirements as well as the environment the product is being used. Be it night time or used during the day or the complexity of the graphic layout, Linepro will assist you in developing the optimum lighting solution for your needs. To know why our exclusive range of Membrane Keypad always trend in the market, click here!

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