For a large-format light box, specify the frame and graphic before choosing LED wattage. Size, depth, light transmission and internal obstructions determine whether the layout can illuminate the center and edges evenly.
Information to send with a lighting enquiry
- Internal width, height and depth; single- or double-sided construction.
- Frame drawing, mounting surfaces, braces and service access.
- Final fabric or film, diffuser and reflective rear surface.
- Ambient light, target appearance and operating schedule.
- Supply voltage, cable routes and required certification documents.
Viewing distance affects graphic readability, but does not by itself require higher brightness. Judge the display in its intended surroundings.
Compare layout, not just component names
Edge-lit bars project inward from selected frame edges. Direct backlighting places LEDs behind the graphic. Both can work in large formats when the optical design fits the enclosure.
Long bars can reduce mounting and connection points, but may leave awkward gaps around braces or frame joints. Short LED modules offer placement flexibility and can also serve large displays. Compare component count, wiring, uniformity and replacement access for the actual layout.
A long-bar example and load calculation
The 958mm high-output edge-lit bar is specified at 45W, 4400lm ±10%, DC24V and a 14° × 47° lens. It requires an external constant-voltage driver. Four bars total 180W nominal load, or 7.5A at 24V, before operating margin.
That calculation sizes the load, not the optical layout or allowed chain length. Check driver derating, cable and connector current ratings, polarity, voltage drop and feed arrangement. Four-side placement is an option to test, not a requirement for every frame.
Approve a complete sample before production
- Install the selected bars in a full-size frame with the final graphic.
- Check center, edges and corners for dark zones, bands and visible LED points.
- Record settings and, where measurement equipment is available, compare repeatable readings at marked positions.
- Check temperature, power loading, connector access and replacement procedure against component instructions.
- Keep the approved layout, part numbers and wiring drawing with the production specification.
Increasing total lumens will not necessarily remove a local dark area. Correct placement, obstructions or material differences before adding output across the entire frame.