Backlighting technologies: Getting started (part 1 of 5)

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By Steve Baker | Oct 01, 2020
LED backlit user interface

This month we are kicking off a five-part blog series on backlighting. The series will begin with an overview of how to approach a backlighting project and each subsequent blog will review one of the four most popular backlighting technologies: discrete LEDs, light guide film, fiber optic weave, and electroluminescence.  

Why should you be thinking about backlighting?

Backlighting has become an industry standard to augment the functionality and aesthetics of a device. From home appliances to aircraft cabins, and car dashboards to industrial controllers, backlit devices and accents are becoming increasingly ubiquitous. Backlighting is a simple way to improve visual appeal, enhance the user experience, and lend a distinctive style to your user interfaces. It can assist and guide users towards the correct operation of a device, especially in dimly lit and dark environments. It also provides vital feedback about user actions and interactions.

How to determine the most optimal backlighting solution?

Designers and product development teams often wonder when the right time is to start thinking about backlighting when developing new products. Ideally, backlighting should be considered at the very beginning of the design phase. This gives you the flexibility to evaluate available technologies and allows engineers to integrate backlighting seamlessly with the other technologies and features of the design.

To establish the best backlighting solution, the first step is to create a list of requirements and assess the proposed design. Start by asking these questions:

  • What environment will the device be primarily used in - indoor or outdoor?  
  • Will the device be primarily used in ambient light, bright sunlight, or dimly lit spaces?
  • Do you want to light up a small indicator window or backlight large areas like texts and graphics?
  • How many colors do you need?
  • Will all the areas be lit at once or do they need to be independently controlled?
  • Are there any buttons or snap domes that need to be integrated into the design as well?
  • What power type is available – is it a portable unit or a plug-in?
  • What are the cost constraints?

Backlighting design concerns and considerations

Based on the responses to these questions, you should be able to evaluate which backlighting solution or combination of backlighting solutions could work with your device. Once you have evaluated and selected the most appropriate technology, you need to address all the design concerns and challenges that the technology presents. A few parameters to address include –

  • Will the light source create hotspots? If yes, how can they be mitigated?   
  • Will the light bleed from one section to the other? Do I need a light-blocking layer? 
  • Is the construction stack-up too thin or too thick for the design? 
  • Is the backlighting affecting the tactile feedback of the buttons or switch technology? 
  • What brightness level does the design demand? 
  • Should the light source be mounted on a printed circuit board or printed membrane? 
  • What are the minimum and maximum sizes of the light source that can be used in the design? 
  • How many light sources do I need? 

It is the interplay of several factors that ultimately dictate and influence the design, each of which is important when examining the cost structure of the project. While this is not an exhaustive list of design considerations and concerns, it provides a framework to effectively begin to approach your backlighting project by forecasting design hurdles and addressing them promptly. 

To dive deeper into the four most popular backlighting technologies, read our other blogs in this series -