we looked at LEDs and dismissed them in a single afternoon. reasons as stated earlier somewhere:Originally Posted by Kaitain
1. You need about 100 ultra bright LEDs for a 7" screen (or equivalent see Luxeon stuff)
2. LEDs need depth. the CCFL inside the screens is only 2.6mm in diameter. You will not get an LED that shallow so wouldhave to go edge lit.
3. Going edge lit you have to mount all the LEDs around the edge and then have a nice interface with an acrylic light pipe
4. mounting 100 LEDs around the edge is hard - you canot do it around the bottom as the LCD ribbon is in the way along the whole edge.
5. Wiring together 100 LEDs is a pain in the *ss!
6. Dimming the LEDs can easily be done using a PWM circuit
7. you can get 3W Luxeon stars that are as bright as 60 ultra brights but they need a CPU style heatsink for each one and they run at about 70deg C
8. LEDs used directly behind will give bright spots on the LCD
9. You can get the required depth using a lilliput screens but not xenarc as they have a side ribbon to the panel.
Personally i would love to use LEDs but there are too many complications. I know how to fix lots but i can't tell you due to the IP restrictions of my Uni.
EDIT: i actually came to the same conclusions in one day as my uni did after a 6 months but i dont want to stitch them up and release stuff on the internet