Ace_3000....pictures of Projector?

[mathias]

Elliptical reflector.............. makes the par30 a joke .

Par30 is for parallel light which many lcd-projectors need and some dlp too and it´s just an alternativ solution. Elliptical reflector is nothing new we talked about that too earlier.

Color temp isnt a problem, you can change the colour temp with a filter, and the projectors colour wheel can also be ajusted for colour temp..... most have this spec built in the menu.

No sorry you can´t do that, try puting a yellowish lamp as backlight to a lcd and then try to adjust the colours on the lcd-panel, it will never look like real white, I have tried. Try a HTI-lamp.

[ace3000_1]

No sorry you can´t do that,

Mathias, i have done it. Dont beleive me? get some cold mirror that has a 800k ^ colour shift and try it yourself. It works well on lcds........... If you also use a decent dichoric ellipsidal reflector before the cold mirror, the upshift in colour is even more, (as high as 1600k and up, when filters are matched).

Yess we have discussed the elliptical reflector somewhat. The difference being here is that, i own 3 brand new elliptical reflectors and have tried both the par30 and the ellipsidal reflectors (along with many others) in reality, and hands down, the elliptical wins by a long shot everytime!!! Buy one, you will never turn back .

Lcd use both parabolic and ellipsidal, DMD (single chip) will only use ellipsidal. It is impossible with todays lamps to use a parabolic on a single chip DMD system, not unless you have a reflector and light source capable of being 15mm in dia, and parabolics are just too inefficent for a DMD system.

http://www.plus-america.com/papers.html

The light that goes through the colour wheel is strait from the ellipsidal reflector, after the colour wheel it is condensed (with a condensing system) to parallele light, it then bounces off of 2 front surface mirrors (1 concave, 1 flat) angled at 12deg, and then reflected off of the dmd through the lens. Any light that isnt reflected through the projection lens (when the pixel is turned off) goes strait to the roof of the light engine.

Trev

[ace3000_1]

try puting a yellowish lamp as backlight to a lcd and then try to adjust the colours on the lcd-panel, it will never look like real white, I have tried. Try a HTI-lamp.

Thats right. One big advantage over lcd with dlp is the fact that you CAN change the colour of the lamp through the use of timing on the dmd mirrors and the filters on the colour wheel. You do know how DMD works right? Its how you can change the colour temp in the menu. The light source colour doesnt actually change, the light being filtered to the DMD does through the timing of the mirrors being turned on and off (upto 5k times per sec) with each colour in the wheel. DMD colour wheels also have a clear filter for direct access to the source for a whiter, brighter image. There is no colour offset like the polarisers on a lcd, unless you introduce one by changing the colour temp in the menu.

Lcd's use a fixed colour system in which the only thing you can control is gain. The colour of an lcd is off with our lamps because of the colour shift in the polarisers.............. which cant be changed other then changing the lamp, or filtering the light externally to a higher colour temp.

Trev

[sn1009]

Hi Ace

Im new to this diy projector thing so bear with me if this is a noob question =)

I've been reading most of this thread but haven't been able to see why use choose to place a mirror in your projector.
IMHO I would have thought that using an arrangement without the mirror would equal less light going to waste.
Something like this:
arrangement

I can see that almost everybody building a 7" projector uses the same arrangement as you do so I guess there's a good explanation.
I guess this has already been mentioned so if you could point me in the right direction that would be great..

Also I stumbled opon this beauty in the german diy-community:
Link

I can see that it's been a while since you've put some photos in this thread so thought the people following your progress needed something to keep up the drooling =)

Nice work on your projector BTW.

Best regards
Søren W.

[ace3000_1]

Heya Soren, welcome to the forum , thanks for the nice words aswell.

The reason i used a mirror is simply because of form factor. Rather then having somthing very long, we can make it into a flat square , or compact if youd like. The loss from fs mirrors isnt great at all, (if noticeable) providing you use fs mirror of reasonable quality. Try to get somthing thats 98% reflective, that way there is only a estimated 2% loss per mirror.

I can see that almost everybody building a 7" projector uses the same arrangement as you do so I guess there's a good explanation.

Not realy, just basically for form factors and limitations. In my last design i use 3 mirrors for a different purpose other then just the form factor, (2 FS mirrors 98% reflective, and a cold mirror). I use 3 mirrors in that system for size, colour temp and heat control.

Also I stumbled opon this beauty in the german diy-community:

Thats a nice projector, almost looks like my first

Trev

[sn1009]

Hi Trev

Thanks for the reply..

As I mentioned I'm new to this so for my first projector I'm looking at constructing something as simple as possible..

I really like the idear of the one I linked to as it is all adjustable.

But I'm still just researching and will probably be doing so until the winter as I've got some other projects that need some attention before I start a new project...

Anyway I've read that you are able to supply most of the stuff that is needed to constuct one of these 7" projectors so if you could drop me an e-mail at sn1009@gmail.com with a list of the stuff you stock that would be great.

Thx
Søren W.

[ace3000_1]

As I mentioned I'm new to this so for my first projector I'm looking at constructing something as simple as possible..

That sounds great, simple is quite often the best way to go about things, large or small . Take your time and you will have a winner.

Trev

[mathias]

Thats right. One big advantage over lcd with dlp is the fact that you CAN change the colour of the lamp through the use of timing on the dmd mirrors and the filters on the colour wheel. You do know how DMD works right? Its how you can change the colour temp in the menu. The light source colour doesnt actually change, the light being filtered to the DMD does through the timing of the mirrors being turned on and off (upto 5k times per sec) with each colour in the wheel. DMD colour wheels also have a clear filter for direct access to the source for a whiter, brighter image. There is no colour offset like the polarisers on a lcd, unless you introduce one by changing the colour temp in the menu.

Sorry to be bothersome.
Yes I know how dlp works, in fact very good. The on off timing of the DMD mirrors you are talking about, is just a simple DA-converter for light. Do you know what PWM is ? If you want to control the lightlevel of a lamp or the speed of a DC-motor you normally use PWM. PWM and DMD are the same thing a "digital to analog-converter". When it´s come to colour, lcd and dlp are the same thing: A colour filter. What you can´t do with lcd, you can´t do with dlp. DMD can´t do magic things, it´s just normal mirrors. Take a normal desklamp, what colour filter can you use to get the lamp whiter ?

If you can change the colourtemp with a cold mirror or not, I will leave that unsaid, but I wonder HQI don´t have much IR.....and you don´t use a cold mirror in the dlp-projector ?

Yess we have discussed the elliptical reflector somewhat. The difference being here is that, i own 3 brand new elliptical reflectors and have tried both the par30 and the ellipsidal reflectors (along with many others) in reality, and hands down, the elliptical wins by a long shot everytime!!! Buy one, you will never turn back .

The discussion we had in the other thread was about if it was possible to put a HQI-lamp in a lcd or dlp-projector, not about which reflector to use. No sorry I will not try an elliptical reflector, the development goes on and so do I with my new diy-projector, now I need HDTV 1920*1080 and crt contrast rate, no lcd no dlp no crt....

[ace3000_1]

What you can´t do with lcd, you can´t do with dlp. DMD can´t do magic things, it´s just normal mirrors. Take a normal desklamp, what colour filter can you use to get the lamp whiter ?

Mathias, maybe you ought to read back and look for the word "polarisers". DMD doesnt use polarisers hence why there isnt the colour offset that you get with lcd's.

Take a normal desklamp, what colour filter can you use to get the lamp whiter ?

I realy though you would know this.............obviously a filter that will filter out the colour you dont want, ie NIR- the edges of red - pink. You would have to take a look at the spectral colour range of your lamp and remove the colour/colours to give you a higher colour temp. Its typically pink. As for the cold mirror, look up the specs and take a look at the colour shift, why does the colour go higher? cos it removes the red on the borderline of IR (well pink), awell as the IR. Perhaps you could ask yourself this: how do i get a blue light colour out of a desk lamp?

and you don´t use a cold mirror in the dlp-projector ?

Well if you know how dlp's work so well, perhaps you could explain to the rest of us how dlp's are cooled and why there is no need for a cold mirror in a typical DLP setup . A heatsink should ring a bell............

Some pro projector lights do actually have a IR filter installed, infact most do, why? not cos of the temp of the dlp chip, but because of the bearings on the colour wheel. The Infocus X1 had a big problem with this, where the bearings on the colour wheel would overheat and fail. And thats why Infocus tells you not to run the X1 any longer then 4hrs.

The on off timing of the DMD mirrors you are talking about, is just a simple DA-converter for light. Do you know what PWM is ? If you want to control the lightlevel of a lamp or the speed of a DC-motor you normally use PWM. PWM and DMD are the same thing a "digital to analog-converter".

I know what PWM is, "Pulse Width modulator". Its available in digital and anolog forms.

Perhaps it would be wise if you went to the site i posted a couple of posts back and read the white papers on DMD, DMD's are digital . The only converter you will find that converts anything is the AD converter which converts the front end anolog incoming signal from your source, into digital, to drive the DMD.

DMD = Digital Micromirror Device

http://www.dlp.com/dlp_technology/im.../131_vproc.pdf

Trev

[mathias]

Perhaps it would be wise if you went to the site i posted a couple of posts back and read the white papers on DMD, DMD's are digital . The only converter you will find that converts anything is the AD converter which converts the front end anolog incoming signal from your source, into digital, to drive the DMD.

Do you have digital eyes ? DMD is the same as PWM, both converters use small timeperiods to create many levels from just one level. The main reason you can do this is because the target (our eyes, the lamp, the motor) is too slow, so they understand the high speed of the DMD or PWM as a analog level. The PWM technics is used in many many electronicsdevices and DMD is the samething but for light.

I realy though you would know this.............obviously a filter that will filter out the colour you dont want, ie NIR- the edges of red - pink. You would have to take a look at the spectral colour range of your lamp and remove the colour/colours to give you a higher colour temp. Its typically pink. As for the cold mirror, look up the specs and take a look at the colour shift, why does the colour go higher? cos it removes the red on the borderline of IR (well pink), awell as the IR.

Yea, sorry I had wrong there, you can use a filter to get higher colourtemp, but.......... you also lose 50% of the light with this colour correction, and that is probably why no one use this in a projector. They use the right lamp from the beginning 5600K-6000K. But if 4200K is OK then use it, but if you have seen the originallamp you will probably think something else.