The backlighting of membranes switches or graphic overlays can create create a dramatic visual effect especially in low-light environments.
There are many ways in which to backlight your membrane switch. Each method has its advantages and disadvantages. We provide our customers with five different options so you can find the perfect system to meet your backlighting needs.
Traditional – This method utilizes incandescent or LED lights on a plane behind the membrane switch. Often these light sources are assembled on a PCB or attached to a sub panel. Depending on how much of the membrane switch needs to be backlit, the membrane switch is then assembled to a clear backer or to a panel with cutouts.
Phosphorescence – Most people have seen or used products that incorporate glow-in-the-dark materials. Phosphorescent inks have been developed to allow us to incorporate this type of backlighting into the graphics we use for our membrane switches. The duration of the glow is brief, but this method provides a very economical backlighting option.
Electroluminescence – Timex’s Indigo watch is perhaps the most well-known user of electroluminescence backlighting. Like fiber optic technology, electroluminescence provides backlighting and is done on a very thin layer between the graphic overlay and the circuit. However, unlike fiber optics, EL uses a printable ink deposit to illuminate the switch. Some of the every-day uses of EL are: pagers, mobile phones, GPS units, etc.
Fiber Optic - Fiber optics provides a flexible back lighting layer that can be incorporated between the graphic overlay and the circuit layer allowing the entire surface area of the membrane switch to be backlit. This technology is not completely new, but its use as a backlight in Membrane Switches is quite valuable. Light enters a fiber optic panel through each fiber end. Computer controlled "macro-bends" cause the transmitted light to be emitted from the sides of the fibers through the cladding. The light emits uniformly up along the length of the panel. Fiber optic applications are valuable where low electronic "noise"', or "interference" is necessary. The fiber weave is designed to match the shape of the switch, 100% customized. Fiber Optic Backlighting is safe, long lasting, and reliable. It will never wear out as the light source can be replaced. Other applications of fiber optic lighting are found in surgical applications, lazer tag vest lighting, lighting in explosive areas, etc.
Embedded LEDs – provide the most affordable method for backlighting. They are most commonly used as indicator lights. It is also feasible to use LED's as a backlight for small icons & symbols. With larger icons & symbols it is difficult to achieve uniform backlighting with embedded LED's.