Having done a reasonable amount of research (clearly not enough) I'd value some assistance in selecting LEDs to make large 7-segment displays for outdoor use.
The application is for clocks/timers, with a viewing distance of 100m, reasonable viewing angle (ideally two displays at 90 degrees to provide near 180 degree viewing angle), for a product to run from mains (240Vac) or portable (12Vdc). Using two 7-segment characters for each display module.
Can anyone suggest either some suitable 7-segment displays (ready made - I can't find any) or LEDs suitable for making some bespoke displays?
Considerations include:
Brightness: How many lumens/mcd per segment are required for 100m visibility outdoors (full sunlight)?
Forward voltage: I expect to require higher than a 12V supply for the LED segment (daisy chain), using a boost converter to achieve the required voltages from a 12Vdc power source (battery) but it (Vf) needs to be reasonable.
Forward current: anticipate using constant current drivers to drive the LED segments, again needs to be reasonable (1w max).
Cost: each 7-segment display needs to be under £50 if buying and under £25 component cost if building, for the overall product cost to be viable.
Power: a consideration for the batteries - spec is four 7-segment displays (2 modules with 2 characters each) running for 6 hours of operation.
Heat: heat sink / heat management to avoid the LED junctions overheating (eg high power LEDs)
Viewing angles: In theory 90 degrees viewing angle per segment/display but in practice would the LED viewing angle need to be this high to achieve good/acceptable results across 180 degrees with two displays fixed 90 degrees to each other?
Quantity and arrangement of LEDs per segment?
If it helps (not much) a decimal point is not required - just the 7-segment characters.
If anyone has experience in this area and can offer some assistance\guidance it would be greatly appreciated.
With so many LEDs to choose from - you could save me a lot of pain and headache. Thanks in advance.
