What is an LED module in a sign?
The part that actually makes the light. A board of LEDs and lenses, mounted behind the face or along the plate edge, and replaced as a single unit.
Back-lit and edge-lit signs both depend on the same component. The LED module is what turns electrical current into the light that the face, diffuser or light guide plate then shapes. Annex 14 sets the luminance and colour the lit face must reach, and the module is what supplies the light to reach it.
1What is on the board
A row of LED chips, each with its own lens to direct the light, mounted on a board that also leads heat away to the housing. A connector at one end joins it to the driver, so the module can be unplugged and replaced as a unit.
2Where it goes
In a back-lit sign the module sits on the back wall and shines forward across the cavity. In an edge-lit sign it runs along the edge of the light guide plate and shines into it. The module is the same idea in both, and only the position changes.
3What feeds it
The module does not connect straight to the airfield circuit. The sign is fed through an isolation transformer, and an LED driver, covered in the next entry, gives the LEDs the current they need. In most designs the LEDs are white and the face supplies the sign’s colour, though this varies by product.
| Element | Detail |
|---|---|
| What it is | A board of LEDs with lenses, built as a replaceable unit |
| Light | Usually white LEDs, with the sign colour supplied by the face |
| Position | Back wall (back-lit) or plate edge (edge-lit) |
| Heat | Carried away through the board into the housing |
| Fed by | LED driver, from the isolation transformer on the series circuit |
| Against lamps | Solid-state, no filament, low power, replaced as one unit |
Frequently Asked Questions
Q1What is an LED module in an airfield sign?
A replaceable board carrying a row of LEDs, each with a lens, that supplies the light inside an internally illuminated sign.
Q2Where is the LED module placed?
In a back-lit sign it sits on the back wall behind the face. In an edge-lit sign it sits along the edge of the light guide plate.
Q3What powers an LED module?
An LED driver, which takes power from the sign’s isolation transformer on the airfield series circuit and gives the LEDs the current they need.
Q4Why use LEDs in place of lamps?
LEDs are solid-state, with no filament to burn out, they draw little power, and a module can be replaced as a single unit.
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