Case Study:
Can LED driven backlighting bring illumination to the darkest of nights?
When a customer came to us with a fundamental logistical issue, RH stepped in to solve their problem. Simply put, this customer needed to find a new supplier for Electroluminescent (EL) lighting. Their current supplier found they were no longer able to supply EL as an ongoing option. We quickly raised a quotation and assured them that we could easily fulfil their immediate needs. During a follow-up design meeting, we proposed several alternative solutions for future consideration. The customer liked our professional recommendations for LED driven backlighting and subsequentially changed their product.
The Challenge:
The client’s existing control panels sit in the driver’s cab of an emergency truck used by a leading UK breakdown service. These controls operate machinery used to recover vehicles that are not repairable at the roadside. The previous Electroluminescent lighting installed into this equipment was to illuminate the control panel in low light conditions.
Consider being a mechanic sent to assist a family in the middle of the countryside on the darkest of winter nights. The only light in the van would be the overhead directional cab lighting which is far too dim. To create a better working environment, you need to see and also feel the controls. Better illumination and tactile response always reduce the chance of operator error. In addition to the extra low light illumination required to read the displays, an additional positive tactile response could also help the user, especially if they are wearing gloves.
The other consideration for a hard-working human-machine interface is the durability of the product. These emergency trucks are out on the road all day and all night. Their job to aid stranded individuals miles from anywhere. The operational needs of the device must surpass its operating parameters. Their working specifications made for rugged and reliable use. Additionally, the device would need to operate in extremes of temperature and humidity whilst subjected to constant vibration.
Our Solution:
When we demonstrated a tactile membrane keypad backlit with LED driven light guide film (LGF), a technology also used in military applications, the customer decided to move to this proposed solution immediately. They particularly liked its ease of manufacture with the enhanced features at a lower cost.
LGF backlighting technology driven by side-firing LEDs that illuminate a thin film of plastic, emitting light from the front face. In the case of a control panel, the total area can display in a single colour. Should it be required, individual regions can be backlit to indicate essential key operation or status warnings. When used in conjunction with different coloured LEDs, or even RGB LEDs, keys and warning displays may be programmed to change colour.
The Result of using LED driven backlighting:
Following a full engineering review of the product, we finally created a tactile membrane keypad with positive feedback, featuring LED-backlit driven Light Guide Film. The benefits of this solution for the customer were clear. They benefited from LED technology’s enhanced life compared to EL while also creating a more cost-effective product. The LED lighting used in LGF is a more stable construction, and over time does not diminish in luminosity the same way that EL Lighting does. This LGF solution also means you do not require a power inverter to drive it and makes LED lighting always fit for this purpose. Another advantage of LGF is that it is much thinner than the EL. The result is that LGF will fit more compactly into any device, aiding both a customer’s design functionality and more uncomplicated component assembly.
The Feedback:
Following the successful introduction of LED driven LGF technology, our customer has not looked back. We continue to receive regular orders, and there have been no reported quality or service issues. We now supply standard LGF membrane circuits required to assemble their product and place discrete orders for digitally printed graphic overlays. RH regularly produces artwork variants of the overlays to dedicate their product by type and for branding purposes. The customer carries out the final assembly of the overlay to the circuitry before assembling the end-user control unit.