My 7" LCD projector

parallax20

Member
2005-03-11 11:40 pm
UK
My 7" LCD projector

Hi everyone,

I thought I'll post my first time experience with building one of these fab devices. I spent many months, probably 3 months in total just reading up on the theory and viewing the great results people with their 15" LCD versions really got me enthusiatic about my mine. So I took the plunge and went for it. But instead of the 15" tft, i opted for the 7" lcd version.


Parts I used:

7" 318GL-70TV Lilliput LCD - res 480 x 234 approx
250w MH and ballast extracted from lowbay light setup
10mm Glass
2x fresnels
80mm triplet
7mm MDF
L shaped angled brackets
2x 80mm pc fan
keyboard shelf slide brackets
ikea ladel for reflector


My reason for going with the 7" LCD was for portability/money/space reasons. Plus the thought of buying a 15" to take apart just seemed abit risky for a first time projector. The overall size of the box is about 40x30x20cm and is comparable to a midi pc case. Perhaps I should have used a PC case, but gutting the insides of a pc case and cutting the metal casing just seemed like too much hard work. Better to work with materials that are easier to manage like wood! :)

Fresnels has to be cut to size, so I used my dremel for that task. It was an easy enough job, make sure you have a face mask on, the plastic debris really fly. The LCD was easy enough to strip and I made a custom frame to hold the LCD and the controller boards out of visible view. I had 10mm glass sheet that I cut to size and positioned this in front of the first fresnel to keep the heat away from the LCD. It is not UV/IR coated, so no real protection but mainly there to keep the heat behind the glass and expell it through a fan on the side. I didn't want my fresnels melting because of too much hot air.

The general design is pretty simple, with two sections. The top level contains the LCD, fesnels and light assembly, whilst the bottom half stores the ballast and power supply. The height of the box caters for the length of the MH bulb used, 30cm high approx. To keep the box length short, I used a keyboard shelf bracket that allowed the projection lens to be adjusted for focusing, and retractable when not in use. I think the worst part of the build was painting the box, it was such a messy process. The good thing about this design is you can make it smaller if you exclude the bottom section from the design, or upgrade to a 15" lcd and remove the middle shelf and put the ballast in an external box. You're only limited by your imagination as they say.

Anyway, I've attached a rough sketch of the internals and some screenshots of early images. Sorry if the images are a bit grainy, my camera isn't very good, but you get the general idea.

The projector is actually finished now, but I've not had any time to take new photos. I'm too busy enjoying my creation. There is a lot of conern about the image quality with low res screens and I have to be honest and say the screen door effect is visible on my 60' projected image. But its by no means distracting or un-useable. Its comparable to staring at a 32" tv at 2 feet way... you can see the individual lines if you look close enough. I use it for tv, video and ps2, so low res is adequate for my use.

In total this project probably cost me just over £200 to put together, which is pretty good with replacement bulbs going at £25 a pop. Be careful as build costs can slowly creep up unexpectedly with fancy extras. Although there are now commercial projectors going for under £400 with SVGA quality.
 

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parallax20

Member
2005-03-11 11:40 pm
UK
Nick, the Troy image probably had some light bouncing onto the image as it was taken when the projector was incomplete and had its air vents exposed, but the GT4 pics definitely don't. The image is crisp and clear, the shots are not representative of what the actual output image. I'm not too good with my camera and simply used the defaults, its a 2.1 cybershot from 3 years ago.