What do you think ?

I dont think a car's headlight is as bright as a projector needs to be. I believe most of them are around 100w.

There were some posts about this earlier. I believe the problem with a headlight is that it does not give even lighting.

Well that sucks.

If not the bulb, then what about the reflector ? would that work better than what you guys use in your pj's ?

A car's reflector is almost never a point light source. They are designed to project a fan like beam horizontally to illuminate the road and not blind other drivers; hardly the ideal light source for a pj.

man i suck at this

A car's headlight reflector is more or less parabolic, in order to produce a beam which will penetrate into the distance. The lens in front of it shapes the beam to a more usable shape to also illuminate to the sides and some upwards for overhead signs, leaving the bulk of the beam hitting the road in front of you.

Remove the lens effects, and mask the bulb so that you get a straight beam, and you may be able to use that kind of reflector with a 7" LCD without the need for a collimating fresnel.

The next problem is the amount/quality of hte light. Halogen lights are too yellow. Even though they're vastly superior to tungsten sealed beams, they're still far too yellow for projection. They're also relatively low power. 100W is actually brighter than is legal for on-road use. Though some driving lights will use 100W bulbs, the majority of high-beam lights are 65W and under. (Yes, you can get overwattage bulbs, but they're not legal, and you can get a ticket.)

Okay... We can go to the expensive solution. HID lights are avaialable for cars, high end manufacturers use them, and even convesion kits are avaialble for those who want 'em. The HID lighting is a much better white, (Though it still could be better) Do not even consider the fake "HID" bulbs which are really just standard halogen bulbs with a blue tint! -- The blue tint actually removes a large amount of the lumens that the halogen bulb produces! By going to the HID solution, you'll need a ballast (Starting to sopund familiar?) to run them. The bulbs for the HID lighting are still generally lower wattage, though.

The problem is one of scale... Go into a warehouse store (Costco for example) and look at the light fixtures overhead. Those are 400W metal halide fixtures. It illuminates the store quite nicely, even at night. Now imagine if those bulbs were replaced by car headlights... (Or look in the parkade of a shopping mall at closing time after dark.) Not so bright anymore, in fact it'd be kind of gloomy. In spots between the lights, it'd be too dark to read the labels... That's the kind of difference in your projection that you'd get.

So... Not to burst your bubble, but that's the kind of problem you're facing.

And last... The reflector... If you've got a bright enouh bulb that will fit in the reflector (And if you can remove the lens from the reflector) and you're using an LCD which is the size of the reflector (Or smaller) then you could do it.