Thursday, April 14, 2016

Focus enhancement of my DIY 2k beam projector

This post is to share information to enhance the focus of DIY beam projector.
I've enhanced focus capability of my DIY 2k projector.

The limitation of DIY projector is blurry images at edges and corner points.
That is caused by the large light emitting area.
Commercial projectors adopt LED light source with small emitting areas.

Simply, we can remove the blurry image and get perfect focus by adopting the LED of small emitting area.
Most of us think that we cannot buy that kind of LEDs in a reasonable price.

After searching that kind of LED more than one month, I finally found nice solution!
The keyword was "medical LED".
CBT-140 from Luminus has 14mm^2 light emitting area which is smallest as far as i know.
The conventional LEDs for DIY projectors (from China) have more than 100 mm^2 that leads to blurry images..

The price seems resonable in It cost more than 100 USD, but less than 200 USD with 100 watt LED driver.
Though the maximum running power is 100 watt, it can solve all of the focusing issues in DIY projectors.
As I contact to Luminus, they say it can run upto around 120 watt w/o troubles once cooling is done enough.

Anyway, I bought CBT-140, applied on my 2k projector and tested.

The original 128 watt LED used in my 2k projector has more than 200 mm^2 light emitting area...
Most of LED DIY projectors adopt this kind of ugly LED.

Ordered from
The heatpipe in the picture will be never used, as the heatsink wings have "U"-shape.
@#$JK@#K%J@3 They didn't send the LED itself !!!!

They quickly sent the LED.
The heatpipe was took from 2k projector.
And I made M3 screw taps to hold CBT-140.

This is CBT-140. Looks very fancy.
That small LED emits 100 watt power !

Combined with LED heatsink holder which is used in the 2k projector.

Looks like this.

This rectangular-shaped condenser lens is commonly used to enhance the brightness.
But it makes image little yellow at left and right edges. (can be solved by using normal round condenser lens)
I don't care at this moment, the prime is to get perfect focus.

This heavy power supply is also from
I bought 120 watt PS, but they sent me a big 150 watt PS haha..

Tested with PDF file.
Cannot see from the picture, but I can distinguish every pixels with my eyes.
The focus is even more than commercial DLP projectors!

I took picture at the corner.
Due to cell phone limitation.. it looks not perfect.
But, again, I can see all of the 2k pixels.

Near center. I can surely say it is perfect focus.

Other two sides.
As I opened the 2k projector and didn't care of dirts, you can see dirty images... :(
My lens and LCD consumed dirts :(
It's ok, as it is a test step to make 4k projector.

I took several video with 2k trailers in youtube.
Sorry for poor resolution of my camera.
Just wanna share the feeling.

If you are going to make a DIY projector, do not go for the cheap LED arrays from China.
You will end up with blurry edges.
The only LED driver for CBT-140 is 100 watt. You may feel it is not that bright.
But it solves all of the focusing issues in DIY projectors.
Better to have a dark room, if you can make 2k projector costing less than 1000 USD.

I will definitely use CBT-140 for my future DIY 4k projector.
See you!