Cheap Improved LCD Overhead Projector

Step 7 End result

See the pictures below :)

Comments

[Exiumind]

image looks kind of dead to me.. any way to enhance it? maybe the contrast or brightness of the lcd matrix itself?

[afunkle]

the only area you will want light to come out of is the main lense area/mirror top.

[afunkle]

im posting up top as a reply, you should improve image quality of these projectors by building a cardboard box over the top of the projection unit. light bleed out into the room from the main projector unit itself is probably causing the image to look faded. obviously leave a hole where the glass mirror is so the projector image will go through the box. you may have to monitor for heat, you will want to make the room light tight as possible, even if you have to put a blanket over the window at night and cover clock radio led's etc. because even a small bit of light will wash out the projector image. make sure you monitor for heat when you put the cardboard box over the unit and watch for heat dammage as this is untested, you may have to put small fans in the unit to blow out hot air if thats the case. hope this helps, i experimented with a non projector and simple cardboard box and mirror and lense and got ok results along time ago. havent had the funds to try a projector modification.

[jordster1998]

how much in total would it cost to build this projector

[DJ_JS9]

well i think i found a filter that will work... https://www.adorama.com/BW27UVIRDP.html i ordered one already and i will let you know when it gets here i think you can find them cheaper but something just said this one!, this one!

[DJ_JS9]

well it got here and its alittle too small ima see if i can make it fit otherwise im going to see if i can send it back for a bigger one. its prolly not super important anyway beacuse none of the oth guides use them...

[TheCheese9921]

did it fit?

[0utbreak]

Nice work !

[waltermelons]

hey, cool Idea! I've been trying to figure this thing out for years! oh, one thing. you need to flip your lcd over, if you don't the projected image is going to show up backwards.

[KT Gadget]

Usually overhead projectors are built so both the presenter and the viewers will see the same image right side up, even though one image is regular size and the other is blown up for a large crowd to see. It's usually the orientation of the screen, so in a sense its getting it to be right side up and not upside down. Plus making sure that the display itself is not flipped over so that both parties are not reviewing the picture backwards. Other than that, I am in the process of finishing my own, but I am using LEDs (with an amp driver) to light up the screen. This is better than the standard lamps used in O.H. projectors because of less heat, but light output is sacrificed. However, just one of these high output lights is almost enough for a replacement bulb, although the room needs to be quite dark.

[commando417]

good but is in step #5 i believe I can't see what the other two boxes are in one of the picturesotherwise good im going to use your IR UV filter idea for my own thankyou:)

[kolokoydog]

can the projector bulb be remove since it only generates heat not the brightness or improvement of the quality of the picture of the lcd?

[1337chaos]

you dont understand how overhead projectors, or LCD's work. let me put it simply: an LCD screen itself is a thin piece of almost glass-like material, behind that is a backlight. without the backlight, you cant see the screen. the backlight pushes its light THROUGH the LCD screen, and into your eyes. without the backlight, the screen just looks black. a overhead projector uses its lamp as a backlight. which is why you use clear pieces of paper to write on. the light goes through the paper, into the mirror, and onto the wall. in this project, he's using the LCD screen itself, with the backlight removed (if the backlight was still attached to the LCD, it wouldnt work, because the lamp from the projector cant go through metal ;) he's using the lamp from the projector as a replacement backlight, which is about 30x stronger than the LCD's original backlight. the projector lamp supplies enough light that it can project it onto a wall in a not-overly-dark room. otherwise you'd just be... well... it would be like taking a monitor, putting it in front of a mirror, and trying to watch the reflected screen on your wall, and it wouldnt be bright at all... hope this answered your question!

[bwpatton1]

a good way to demonstrate a back-light is take a laptop, find the small button at the top right or left of the keyboard (all the way up almost to the screen) and push it down. this will make the screen go "black". thus demonstrating a screen without a backlight

[kolokoydog]

well couldnt u just max out the brightness n contrast of ur lcd to make a good pic out of the projector?

[linkaylomen]

I think you really need to learn how an OHP works before you could start this project, its very simple and easy to understand how they work and why.

OHPs are very basic in design so I trust you will understand this article:
http://en.wikipedia.org/wiki/Overhead_projector

I know Wiki isn't concrete for info but this article is good for the intended purpose.

[rujoesmith]

how are you going to max out the brightness with no backlight?

[vonFelsenheim]

I think the question was something like: can you leave the monitor intact with the brightness turned up and just project the image with the OHP turned off? The OHP lamp is a heck of a lot brighter than an LCD monitor, of course. But even in a nice dark room, you need the OHP's fresnel to collimate the light so it will project without blurring. Interesting. Could you remove the frensel, place it in a frame OVER your intact LCD and have that project? Time for experiments, I think.

[1337chaos]

It's not going to project unless you have a lamp large enough to actually project the image. Placing a fresnel lens in front of a monitor will do nothing but make the image look larger than the monitor is. It's the same concept that's used in DLP and older bigscreen tv's. It's nothing more than a reverse OHP. It uses the OHP glass lens and mirror on the inside, and the fresnel as the screen.