Pyrex as IR Filter in 5" LCD projector.

[mengalva]

Hi Diyers !!

After many months reading all the knowledge collected in this great forum I decide, as many others, to begin my own projector based on projects done by many of you of course

I decided to go with the PSone LCD and not with the Lilliput for 2 reasons:

1. The throw distance cannot be more than 9' because of the room dimensions and I have seen good results with PS1 LCDs at that throw distance (I want it to watch movies, not for gaming). I'm expecting a 60" to 80" diagonal image size.

2. The second and principal reason: I'm a happy married man , my budget is limited and the Lilliput didn't fitted in it.

This is what I got for the moment:

- OSRAM HALOPAR 30 as reflector (going to cut it as MATTIAS did)
- CDM-T 150W (with UV filter), G12 base and ballast
- 5" PSone LCD

Parts from a 3M 2150 ohp (obtained free at my job ):

- Condenser
- Fresnels (unslpited yet)
- FS Mirror
- Triplet 330 mm FL

As you can see the only missing part is an IR Filter or a cold mirror and those are not to easy to find in Mexico. I have read that cold mirrors are made with PYREX glass so my question is:

<b><font color="ff0000">Is PYREX a good heat absorbing glass to keep the LCD cool?</font></b>

Because my wife has many PYREX baking pieces waiting in the kitchen for me

[Stocker]

All the pyrex baking pieces I have seen are very non-flat. and thick, with a slight tint to them.

[mengalva]

Originally posted by Stocker
All the pyrex baking pieces I have seen are very non-flat. and thick, with a slight tint to them.

Hi Stoke

You are right, I went to a store and I notice that all Pyrex products have that ugly non-flat and distorted surface.

I have found This company www.rosco.com that have some UV and IR filters and they have distributors in Mexico, also they have hot and cold mirrors in many different sizes, see these links

http://www.rosco.com/us/filters/protect.asp
http://www.rosco.com/us/filters/perm....asp#Technical

I have ordered the 20" x 24" Super Heat Shield for $179 pesos ($14 US dolars) plus 15% tax.

Has somebody had used these filters before?

greetings

[Guy Grotke]

I don't think their Super Heat Shield does much for you, but their ThermaShield would. Super Heat Shield blocks "convected heat" which is a fancy way of saying "hot air". It does not absorb or reflect IR. You can use any glass or Lexan to do this, and Lexan will also remove UV.

Rosco's Thermasheild is more expensive and works as a hot mirror: It actually reflects IR and lets visible light through. It is a plastic film, so you would need to put it several inches away from the lamp so it doesn't melt.

[part2wanksta]

dont worry you will enjoy your nice and cheap psone projector

[mengalva]

Originally posted by Guy Grotke
I don't think their Super Heat Shield does much for you, but their ThermaShield would. Super Heat Shield blocks "convected heat" which is a fancy way of saying "hot air". It does not absorb or reflect IR. You can use any glass or Lexan to do this, and Lexan will also remove UV.

Rosco's Thermasheild is more expensive and works as a hot mirror: It actually reflects IR and lets visible light through. It is a plastic film, so you would need to put it several inches away from the lamp so it doesn't melt.

Thanks for the advice Guy , you are absolutely right. After reading the specifications with more attention I notice what you said, so I call and change my order for a 12" x 12" Thermashield, it´s about the double of the price but I'm sure it will do better the work of staying the LCD cool. I'm planning to put it about 6" away from the lamp so it doesn't melt. Do you think it's a good distance? my bulb is a cdm-t 150W with UV blocking coat

Originally posted by part2wanksta
dont worry you will enjoy your nice and cheap psone projector

Thanks for your support part2wanksta , I think this is all about experimenting and enjoying this hobby

Greetings

[Guy Grotke]

They recommend some free air space on both sides, so I would not put it closer than 1/2" from the condensor fresnel. I think it would also be a good idea to have some cooling air blowing across both sides of the film. Six inches from the lamp doesn't sound bad, but why not put it as far as possible without blocking the light at the edges? See if it gets hot when you first try it, but I think it will be fine. Rosco sells this stuff for use in theatre spotlights, so it must be pretty heat resistant!

Please post your experiences with it. There are a lot of unknowns: Does it keep your LCD cool? Does it interfere with the light? Does it get too hot without a lot of cooling air? Is it hard to keep clean? Does it last?

Thanks for trying it! The whole point of these forums is to share new (and old) information. Trying something new and sharing the results is how we can each contribute to the community.

[mengalva]

Thanks for your recommendations Guy, I will make the tests and post all the results of your questions for the community as soon as I have the filter. The distributor didn't had it in stock and they will deliver it to me in 10 days, I must be patient.

For now, I have cut the fresnel lens to the PSone size (actually one inch bigger in height and width) and also the Par30 with the Dremel's Diamond wheel (so easy if you have some patience ).

While I wait for the IR Filter my next steps are to complete the light box and make a mount for the PSone LCD and controller card

Greetings

[neilson182]

Another benefit of using the Thermashield from Rosco is that it boosts the Kelvin temperature of your light source (according to the site). This would be good for your 3m 2150 overhead because it will make the halogen light look whiter. I'm not sure how noticeable the change would be, since Rosco says the thermashield boosts a 3200K source by 300K. Let us know how it goes!!

[neilson182]

...I just noticed that you aren't using the light source from the 3m 2150 overhead, but I think nearly all light sources could benefit from an increase in colour temperature. My CRT has a setting to change between 9300K 6500K and 5000K, as well as custom setting. I usually use the 9300K setting because whites look nice and white!! Good luck on your project