LCD Based 3D Printer - Introduction

[AndersonTa]

http://cdn.intechopen.com/pdfs-wm/6601.pdf

One of the better write-ups I've scene on LCD based SLA systems.

What else can we use for a light source? Seems like at this point, disassembling an LCD and removing whatever layer of UV blocking is the only thing that needs to happen.

[Oneminde]

Here's some interesting info on the panel type etc. Worth a read.
http://www.aspe.net/publications/Annual ... s/1988.pdf

[Phife]

I'll get you guys some pictures and renderings.. hopefully later today.

But to anyone else working on this type of printer, its not as simple as stripping the backlight and films off a regular LCD.. Regular LCD just dont work well for this. The red and green color filters do not allow the wavelength of light we need to pass through. Also, there is not a UV blocking layer on the LCD, its the polarizers that are blocking the UV. Wavelengths of 400nm and higher have no problem passing through the LCD. Im using an LED array with 410nm LED's.

Im using a monochrome/grayscale LCD (see expensive medical monitors). Ive also determined that using a large arc bulb and lenses are not ideal to uniform lighting. You might be able to get a bulb, reflector and fresnel setup working with a 8" or smaller panel well but anything larger and you get trouble with uneven lighting. Also since the polarizers lose around 90% of the light passing through you need a much more powerful bulb.

Skip that whole thing and build an LED array with collimation optics. Ive been testing many different optics, leds, and LCD panels, Ive settled on a good setup that I'll post soon.

[AndersonTa]

Looking forward to your post Phife.

Until you do we all will just keep guessing at whats the "right way" to go about it.

Screen based SLA is a surprisingly old technique that seems to have fallen by the way side. Found some papers that folks were using such a setup for SLA bio applications in the late 80's early 90's.

[Oneminde]

[Oneminde]

Since the polariser limit the passing of 400 nm and bellow, then using 400 nm and above should not be a problem and they do exist. Light curing polymers.
Why tackle a problem that does not exist. If the light does not harm the panel itself, is passed true and eliminates some basic problems the LCD solution creates, then one should go for that.

[PacManFan]

I think the best bet in this case would be to contact a manufacturer of polarizers, and explain your needs for a UV-transmissive polarizer film for an LCD panel. These guys might be able to help:

[Phife]

[Phife]

Heres a few Pictures from the 3d model. Its not complete. I will be spending some time completing it and the actual prototype in the next month. Im waiting for my custom MCPCB and lenses to show up. I plan on selling the entire machine as a kit for people to put together.

I am using Hiwin rails and ball screws for the Z axis. More details and pictures to come. Feel free to ask any questions and i'll do my best to answer them. I will start a new thread when I have more to show.

[Phife]

This is the LED array, 320 pcs of 3w 410nm LED's, and 6 degree collimation optics. Custom Metal core PCB and it gets attached to a large heatsink for cooling as this thing gets hot!

I made it modular and scalable so it can be made larger or smaller to suit different size LCD's.