Hello everyone, happy China New Year! It has been a really long time since my last post. And how have you been?
I have been received many RFQs for round and ring LED backlights recently, and I want to find a chance to explain how we make them. I will make everything very clear, so everyone can understand it.
This is a typical LED backlight.
5 mm light shade area, exterior size 50*50 mm, view area 44*50 mm, 2.0 mm light guide plate and the total thickness of LED backlight is 2.4 mm.
3 pieces of SMD LEDs are parallel connected and driving voltage is 3.0 v.
Ps: what is a light shade area? It usually is the position we install LED lamps. Because it is super bright and it creates a light spot, we have to put a black film at the top.
How do we make a round or ring LED backlight? In my opinion, there are two options.
You may find this picture very familiar because it is on the homepage of my website. Check the link: https://www.displaybly.com/portfolio/72703backlight/
It is a blue ring LED backlight, there is a hole in the middle, 3 mm light shade area. 4 SMD LEDs in the 4 corners: 12 o’clock, 3 o’clock, 6 o’clock and 9 o’clock position. We use 2.0 mm light guide plate and the total thickness of LED backlight is 2.4 mm. The view area looks like ring, but the defect of this design is obvious there are 4 redundant light shade areas. It does not look very round. The advantage of this design is that we can use the existing PCB no matter what the sizes it may be.
Is it another way to make it look much round? Yes, it is. Please see option B and the picture below.
It looks exact like a ring with two wires. 3 mm light shade area and 10 mm active area (illumination area). 4 SMD LED is parallel connected. We use 1.5 mm light guide plate, 0.8 mm PCB and 0.2 mm diffusion film to make this LED backlight, so the total thickness is about 2.7 ~ 2.8 mm. The disadvantage of this design is that if we change the size, we have to make a new dedicated PCB.
Now let me compare these two options.
1 Option A is an edge LED backlight and option B is a bottom LED backlight. Please see my post: The comparison of bottom LED backlight and edge LED backlight
The light use efficiency of option A is better than the light use efficiency of option B because light direction of option A is the same as the illumination area.
If the size of ring or round LED backlght is bigger, it is going to need more LED lamps for option B to match the same brightness as option A.
2 option A has 4 anodes and 4 kathodes and option B only have one anode and one kathode. It is difficult to connect the anodes or the cathodes if we choose option A.
3 what if there is more colors in the LED backlight? Let me see what happens.
Now we can see that option A is not the best solution when there are multicolor in one LED backlight because it has too many anodes and cathodes. Meanwhile, option B is the perfect solution for multicolor situation. It only only has one anode and 3 kathodes( Red, Green and Blue). What if you want 10 colors or 20 colors? It is easy to done than said. Please believe me.
Though this color control module, you can have many colors as you want. And you can change the color with the remote. If you want to know more about how LED color changing, please see my post: LED Backlight Color Production Theory
You are welcome to comment if you have any question. Thanks.