DIY Video Projector Part II

[mycamel]

Originally posted by eebasist
.....you might get a decent effect out of them if you encase them in an old elipsoidal stage light....

That's close to what I'm looking into. After seeing this product:

http://www.premier-lighting.com/tipa/tipa.html

I ordered a reflector and lens from an 8" fresnel stage light from Secoa and intend to experiment away. Not having specific data on the reflector, my fear is that the light source of my big honking 400w MH bulb won't be able to fit anywhere near the focal point. From what I've seen so far, stage lighting fixtures use very small high power bulbs which can fit deeply into a reflector. We'll see once I get it.

I tried to pick up a reflector like marklar's. Cooper makes the Portolio line and sells though Home Depot, so I called them with the model - H7684T. The quote was $181.56 plus $25.58 for the trim ring plus shipping. Youch! Well beyond what I wanted to spend on a reflector!

So, tech head and undream may have the practical answer. What sort of adhesive do we use to allow fairly precise tweaking and aiming of little mirrors inside a form which won't care about heat? Someone a while back had suggested using one of those laser pointers for checking focal points, and that might really help in aligning them in this case.

[eebasist]

I ran into the same problem with Marklar's projector. It was just too expensive.......so i decided the ellipsoidal stage light would be better.....the thing is, with a quartz halogen bulb it could be very good, they are desined to use a relativly large bulb fillament. But i probably wont go that route yet since i've got two working projectors and that only need light sources....time to modify stuff



BTW guys i work in a tech transfer office and have access to many differrent patent search tools.

[prjctr_builder]

Originally posted by mycamel


That's close to what I'm looking into. After seeing this product:

http://www.premier-lighting.com/tipa/tipa.html

wait a minute, the thing in the middle is where the image that is to be projected is placed, right? but the size of this thing seems to be too small to fit a projection panel....are we still going to use a panel.

and, if we use a panel, then to illuminate it's 10.4" we use say 575W metal halide bulb. but if we use a smaller screen, look at this:

10.4 / 49000 = 5.6 / x where the x is the numberof lumens and the first numbers are the diagonals


in this case we will need about 22000 lumenswhich we can easily get from a variety of CHEAP bulbs.


MY POINT IS>>> do we want to use the projection panel and have to use very powerfull and big bulbs? if at the same time we could use a small bulb on a small LCD...


aleksey

[woneill]

Aleksey,

If my memory serves, the calculation you propose should be based on area and not on the screen/image diagonal.

Unfortunately, even doing it that way, it still only translates to the projected image if it is the same size of the panel...

Whether you use a 10.4" panel, a 5.6" panel, or a 1.8" panel: if they are each used to project a 100" image at the same brightness, then the total light flux pasing THROUGH each panel will be equal. (The original light source energy needed to achieve this throughput is dependent on the efficiency of the panel.)

It is the size of the image, and how thinly spread the light energy is over its area that is the final determinator in the required output brightness of the projector...

The flashy new little devices with thousands of ANSI lumens are intended to project big images in big bright auditoriums. To achieve the same brightness in a 4' image on your bedroom wall, you will probably need only a couple of hundred lumens.

The reason for using a bigger panel is cheapness/availability, and the possibility that in the bigger panels, the LCD shutter area is bigger with respect to the TFT transistor area, than it is in the smaller panels. (The LCD shutters compete for space on the panel surface with the TFT transistors which are mounted directly on the silicon surface.) If this increased area ratio is the case, then the bigger panels would be more efficient. Unfortunately, their size introduces other problems as we all know...

Bill.

[CHARTO]

headlights

When i mentioned headlights in my post, i was'nt thinking of using
the headlight bulb, they are just not bright enough

Im just saying use the reflector
on my car i have two fog lamps on the front spoiler,they are about
6"+4", if you were to get somthing like that and just use the
reflector part, adapt it to take one of those high power capsule bulbs, you end up with somthing like whats in an overhead

[Invictum]

Well, I tried out the headlight...at full brightness, the power supply can't handle it. It only stays on for about half of a second. Also, like Charto said, they're just not very bright. Looks like metal halide is still the best bet.

[xblocker]

May be of interest! Here's a pic from 10" single panel projector light unit. Projectors name is 'GP Movin 2001". It's a 4-pack xenon unit with 4x35 Watts. It should last up to 6000h and costs about 76 EUR. Xenon lamps dont produce so much heat and can work with smaller, more silent fans. If somebody is interested:

http://www.gp-elektronik.de

[mycamel]

Originally posted by xblocker
May be of interest! Here's a pic from 10" single panel projector light unit. Projectors name is 'GP Movin 2001".

Cool! I'd never even considered an ARRAY of smaller lights and reflectors! This would help keep the light rays going straight through the LCD apertures. They sort of look like light headlight reflectors, don't they? I'd guess they must use a large high quality fresnel after the panel to make this work. Anyone understand enough German (or whatever it is) to know if its mentioned on the site?

[tomithy83]

Originally posted by mycamel


...I'd guess they must use a large high quality fresnel after the panel to make this work...

youd need the fresnal in front of (before) the lcd. so that the rays are paralell, thats the point of parabolic reflectors. scratch that as long as all four reflectors are parabolic it might work??????? someone let me know please!!!!!!!!

anyway here's a site for metal halide bulbs

home depot dont have ballests

i dont know how much you guys are paying but i've heard/read prices hier than this

sorry bout the spelling im on a wave key board its confusing im a pecker

[Invictum]

Hey, I just noticed this bulb at bulbs.com:

http://www.bulbs.com/products/produc...inventory=9722

Now I know this thing is expensive, but otherwise it seems perfect. The color temp. is good, it lets out 60K lumens, it's only 175 watts, it lasts 7.5k hours, it's not too big, and best of all, the reflector is built onto it. Is this a great bulb, or am I missing something here?