A dark light box corner can come from incomplete beam overlap, a frame shadow, the graphic itself or an electrical problem. It is not automatically normal, and it does not always require another LED. Identify the pattern before changing the component count.
Use the pattern to narrow the cause
| What you see | What to check |
|---|---|
| All corners darker than the center | Layout, end gaps, bar orientation, frame depth and beam overlap |
| A sharply defined dark strip | Brace, cable, mounting hardware or frame lip blocking light |
| One side dimmer or changing brightness | Failed bar, connector, feed arrangement or voltage drop |
| A dark area follows the print | Ink coverage, fabric transmission, folds or material variation |
These are diagnostic clues, not final conclusions. Photograph the display at fixed exposure. Compare the final print with a suitable plain translucent sample to separate graphic effects from lighting layout. Inspect connections with power disconnected.
Correct the primary layout first
Remove avoidable obstructions, check bar orientation and adjust spacing within the component instructions. Test edge-lit and rear-mounted systems according to their intended optical layout. Adding power everywhere may brighten the center while leaving the same shadow.
A compact supplemental module is useful when a tested primary layout leaves a localized gap and there is a suitable mounting surface. It may also create a bright patch if too close to the graphic; test the addition before making it permanent.
A compact corner-module example
The 8W corner LED module is specified at 600–700lm, 202 × 24 × 16mm including lens, DC24V and 10° × 40°. It supplements the main lighting rather than replacing it.
Match its fixed color-temperature range to the primary bars and check the actual color together; similar nominal ranges can vary. Add its 8W load to the driver calculation and verify connector pinout, polarity, cable rating and voltage drop.
Recheck the whole graphic
Compare center, edges and corners at the same settings after the change. Check for a new bright spot, color mismatch and acceptable thermal conditions. Record placement and readings for repeat production.
Compare the 20W primary bar, 13W edge-lit bar and 7W optical module by layout needs. For advice, send frame dimensions, LED placement and photos of the dark area.