two way mirror/screen
Hi there ppl,
did anyone try using 2 way mirror/screen (if that type of mirror is in existence and can be used)? I'm just theorizing here. It's like this:
The image from the LCD (not dissassembled) is reflected by the mirror 1 in front of it (at 45 dgrs to the screen at the bottom of the screen) then reflected to another mirror (at 90 dgrs to the mirror 1 and over the LCD monitor). Mirror 2 being two way with the light behind it. Meaning, mirror 2 reflects the image of mirror 1, and at the same time mirror 2 can let through light behind it (whatever lumens). So without dissasembling it would be possible to reflect and then juice it with light
Now this idea even to me seems like doktor nemo stuff But let's say "what if". I just thought of it coz most of the buildings u c have those windows that u don' c nothing in daylight but c everything at night looking from outdoors. SO:
1. Does this kind of mirror/screen exist?
2. If it does, would it be possible to put the light behind it and project the image to the wall (or whatever) of its (mirrors/screens) surface?
Thanx
Hi there ppl,
did anyone try using 2 way mirror/screen (if that type of mirror is in existence and can be used)? I'm just theorizing here. It's like this:
The image from the LCD (not dissassembled) is reflected by the mirror 1 in front of it (at 45 dgrs to the screen at the bottom of the screen) then reflected to another mirror (at 90 dgrs to the mirror 1 and over the LCD monitor). Mirror 2 being two way with the light behind it. Meaning, mirror 2 reflects the image of mirror 1, and at the same time mirror 2 can let through light behind it (whatever lumens). So without dissasembling it would be possible to reflect and then juice it with light
Now this idea even to me seems like doktor nemo stuff
But let's say "what if". I just thought of it coz most of the buildings u c have those windows that u don' c nothing in daylight but c everything at night looking from outdoors. SO:1. Does this kind of mirror/screen exist?
2. If it does, would it be possible to put the light behind it and project the image to the wall (or whatever) of its (mirrors/screens) surface?
Thanx
partial mirror
Most mirrors you see are 100% reflective. (Well, actually they absorb some of the light, but for purpose of this discussion...) But you can pay much more and get 50% reflective. Pay about 10 times that and you can get a custom mirror with any amount of reflection you want.
But just because the light from both sources would be combined at the half-mirror, does not mean that the LCD image light would somehow control the amount of light that came through from the backlight. The projector you are proposing would send >95% unmodulated white light to the screen, and <5% image light to the screen. You would not be able to see the image. Or maybe you could see the slightest faint trace of it. It would actually look much better if you just turned off the light, and projected the backlit LCD by itself.
Half mirrors work because the light on one side is much brighter than the light on the other side. There is nothing "one-way" about them. If you are on the bright side, all you see is reflected light. If you are on the dark side, all you see is transmitted light.
But it still might be possible to make a device that does what you want: If you made a large array of liquid crystal cells, and each cell was driven by a photosensitive device located on the "screen" side of the cell, then you could use a 1:1 faint projected image from a regular LCD or TV to control the individual cells in the big array. With a strong light source, each cell could act as an amplifier. Of course, this would all be much more expensive and difficult than just stripping the LCD and adding a MH bulb and some fresnels!
Most mirrors you see are 100% reflective. (Well, actually they absorb some of the light, but for purpose of this discussion...) But you can pay much more and get 50% reflective. Pay about 10 times that and you can get a custom mirror with any amount of reflection you want.
But just because the light from both sources would be combined at the half-mirror, does not mean that the LCD image light would somehow control the amount of light that came through from the backlight. The projector you are proposing would send >95% unmodulated white light to the screen, and <5% image light to the screen. You would not be able to see the image. Or maybe you could see the slightest faint trace of it. It would actually look much better if you just turned off the light, and projected the backlit LCD by itself.
Half mirrors work because the light on one side is much brighter than the light on the other side. There is nothing "one-way" about them. If you are on the bright side, all you see is reflected light. If you are on the dark side, all you see is transmitted light.
But it still might be possible to make a device that does what you want: If you made a large array of liquid crystal cells, and each cell was driven by a photosensitive device located on the "screen" side of the cell, then you could use a 1:1 faint projected image from a regular LCD or TV to control the individual cells in the big array. With a strong light source, each cell could act as an amplifier. Of course, this would all be much more expensive and difficult than just stripping the LCD and adding a MH bulb and some fresnels!
reflector for Ushio bulb
JCB at diybuildergroup likes this bulb, and he is getting reflectors and condensors that work for it:
http://diybuildergroup.com/store/glassandmirrors/index.htm
If you want to use smaller optics, there is a very nice double-ended Osram bulb:
Powerstar HQI-TS 250/D product number 4050300 436050
250 Watt 20000 lumens 5100 K CRI > 90
25 mm diameter Fc2 base (connector on each end)
JCB at diybuildergroup likes this bulb, and he is getting reflectors and condensors that work for it:
http://diybuildergroup.com/store/glassandmirrors/index.htm
If you want to use smaller optics, there is a very nice double-ended Osram bulb:
Powerstar HQI-TS 250/D product number 4050300 436050
250 Watt 20000 lumens 5100 K CRI > 90
25 mm diameter Fc2 base (connector on each end)
I emailed JCB and he said that he expects the reflectors and condensors in around the end of the month / beginning of next month. I was just bummed out as I was adding parts to my cart the 325mm Xerox/Fugi lens disappeared before my eyes! It didn't even go to out of stock, just gone so perhaps he won't be carrying them anymore.
Thanks for the great info, Guy!
Thanks for the great info, Guy!
is there any aussie out there
i need some help , i need to know where can i get a fresnel lens for a projector. What sort of light source is required?
Can you give me names of suppliers or where I can find more information. I need details of suppliers in Victoria, preferably Melbourne.
thanks mate!
i need some help , i need to know where can i get a fresnel lens for a projector. What sort of light source is required?
Can you give me names of suppliers or where I can find more information. I need details of suppliers in Victoria, preferably Melbourne.
thanks mate!
Maybe this has already been addressed, but I tried searching for an answer to this and so many threads were returned that it was like looking for a needle in a haystack. (Since this is something that newbies probably ought to know, I thought I'd just append it here.)
Light leakage: it's unclear to me whether we worry about this exclusively because of its deletorious effects on projected black levels... or is it more of an "every lumen is valuable" kind of thing.
To clarify, my projector will likely be mounted in the attic - light source at the top, with only a small portion (containing a mirror and the projection lens) protruding through the ceiling into the theater room. Any light leakage in my attic will not be visible within the theater room, ergo on the screen.
It occured to me that if I have a decent reflector and can properly direct (at least the vast majority of) the light downward to the fresnels/lcd, it might actually make sense to leave this entire section exposed - for better cooling.
Or is that a bad idea?
Light leakage: it's unclear to me whether we worry about this exclusively because of its deletorious effects on projected black levels... or is it more of an "every lumen is valuable" kind of thing.
To clarify, my projector will likely be mounted in the attic - light source at the top, with only a small portion (containing a mirror and the projection lens) protruding through the ceiling into the theater room. Any light leakage in my attic will not be visible within the theater room, ergo on the screen.
It occured to me that if I have a decent reflector and can properly direct (at least the vast majority of) the light downward to the fresnels/lcd, it might actually make sense to leave this entire section exposed - for better cooling.
Or is that a bad idea?
I want to see it!
You'll have to let me come over and see it, after you get it running: I want to see all the little moths, etc. flying around in your image! I don't know about your attic, but all of mine in San Diego had pretty big holes in the attic vent screens.
I think it is useful to paint stuff black or use black felt inside the box, because stray light can reach the image which will lower your contrast. The best results are obtained if all the light hitting each screen pixel comes only from the lamp arc.
I had some reflection from the projection lens mounting surface, going back to bounce off the LCD surface. By gluing black felt to that plywood surface, I got a better image. This is just like using lenses that have anti-reflection coating. Before AR coatings were invented, nobody could make a lens with more than 3 or 4 elements because the reflections would be too bright.
You'll have to let me come over and see it, after you get it running: I want to see all the little moths, etc. flying around in your image! I don't know about your attic, but all of mine in San Diego had pretty big holes in the attic vent screens.
I think it is useful to paint stuff black or use black felt inside the box, because stray light can reach the image which will lower your contrast. The best results are obtained if all the light hitting each screen pixel comes only from the lamp arc.
I had some reflection from the projection lens mounting surface, going back to bounce off the LCD surface. By gluing black felt to that plywood surface, I got a better image. This is just like using lenses that have anti-reflection coating. Before AR coatings were invented, nobody could make a lens with more than 3 or 4 elements because the reflections would be too bright.
lcd panel/monitor
with regards to lcd panels/monitors for making a small footprint projector \, i have been looking for lcd's and parts etc . an dhave come accross a few items of interest.
firstly lcd monitor, now i read in this forum below 7" is not good but look here and advise what you think.
NEC sell a 6.3" XGA 1024x768 pixel response time 6ms , now i found a price online , not real cheap approx$520AUD specs at
http://www.ee.nec.de/products/display/color_tft_display_lineup/020_6_3_modules/NL10276BC12_02.html
can this be used - has any one else used it?
is there a cheaper place to buy it? i saw somewhere buying groups for this sort of item is this something that should be pursued? i see people using the 7" lilliput and innovatek at 2400x480 pixels at substantially cheaper prices i fear this resolution gives too much of a wide screen effect and will affect a standard picture 4:3 ratio too much, thus maybe only outputting 640x480pixels at 4:3 ratrio - any comments welcome.
regards tony
with regards to lcd panels/monitors for making a small footprint projector \, i have been looking for lcd's and parts etc . an dhave come accross a few items of interest.
firstly lcd monitor, now i read in this forum below 7" is not good but look here and advise what you think.
NEC sell a 6.3" XGA 1024x768 pixel response time 6ms , now i found a price online , not real cheap approx$520AUD specs at
http://www.ee.nec.de/products/display/color_tft_display_lineup/020_6_3_modules/NL10276BC12_02.html
can this be used - has any one else used it?
is there a cheaper place to buy it? i saw somewhere buying groups for this sort of item is this something that should be pursued? i see people using the 7" lilliput and innovatek at 2400x480 pixels at substantially cheaper prices i fear this resolution gives too much of a wide screen effect and will affect a standard picture 4:3 ratio too much, thus maybe only outputting 640x480pixels at 4:3 ratrio - any comments welcome.
regards tony
The best is the simplest.
I tried to build DPC MKIII projector because of the smaller size. After spending hundreds of dollars and hours, I found that the best is the simplest without mirrors and a lot of glasses, i.e. the LL design. After I removed the mirror, I found the image is much much better than that with a mirror. I guess this is a reason the screen shots on LL is much better than those from more fancy projectors.
I tried to build DPC MKIII projector because of the smaller size. After spending hundreds of dollars and hours, I found that the best is the simplest without mirrors and a lot of glasses, i.e. the LL design. After I removed the mirror, I found the image is much much better than that with a mirror. I guess this is a reason the screen shots on LL is much better than those from more fancy projectors.
Re: lcd panel/monitor
Hey Tony, check this out. Same part number on American site:
http://www.necelam.com/display/index.php?Subject=Detail&part=NL10276BC12-02
It lists different specs but I think that regardless it would be great if it comes with controller and VGA connector. The contrast ratio listed on the American site would be wonderful for having a bright picture in ambient light with rich colors (black blacks not grey). I may contact the sales people and ask what quantity would be required to get the price down to a reasonable level. I didn't bother to see what the price you mentioned was in US$ because I'm pretty sure it's still way too high. If we could get a group buy in any part of the world the shipping would be a small price compared to the savings (I would think) it would afford. How about you check it out from your end and anyone else out there contact there nearest representative and ask about group rates. I plan to explain exactly what we are looking for.
Just checked it out: 404.617 USD.
Beyond my means.
ozsibe said:
Hey Tony, check this out. Same part number on American site:
http://www.necelam.com/display/index.php?Subject=Detail&part=NL10276BC12-02
It lists different specs but I think that regardless it would be great if it comes with controller and VGA connector. The contrast ratio listed on the American site would be wonderful for having a bright picture in ambient light with rich colors (black blacks not grey). I may contact the sales people and ask what quantity would be required to get the price down to a reasonable level. I didn't bother to see what the price you mentioned was in US$ because I'm pretty sure it's still way too high. If we could get a group buy in any part of the world the shipping would be a small price compared to the savings (I would think) it would afford. How about you check it out from your end and anyone else out there contact there nearest representative and ask about group rates. I plan to explain exactly what we are looking for.
Just checked it out: 404.617 USD.
Beyond my means.
hi guys,
since my last post i have researched it a bit more, and i think i might go with the innovatek 7" screen shown here at $159 USD based on price alone.
http://www.mp3playerstore.com/stuff_you_need/special/In-Dash-7.htm its the same as the lilliput 7" but cheaper with a decent resolution actual 2400x480 pixels.
and i will build it with 2 mirrors one being the cold version to help reduce heat. with some of that IR sheeting ( food for thought - possible that sheeting from car window tinting may do the same job.)
i particularly like this guys design http://www.thegarage.cjb.net/
but with 2 mirrors - he has one mirror . and more specific the lighting arrangement and cost with regards to replcament globes at $95 AUD for 10,000 hrs thats less than 1cent per hour at 250watt,which should be bright enough.
although i particularly like the idea of trying one of these setups. it would be simply unique its a xga resolution screen 0.9" LCOS microdisplay. found here http://www.tmdc.com.tw/images/tmdc XGV0901specificationDM.pdf
love to hear your comments on this
regards tony
since my last post i have researched it a bit more, and i think i might go with the innovatek 7" screen shown here at $159 USD based on price alone.
http://www.mp3playerstore.com/stuff_you_need/special/In-Dash-7.htm its the same as the lilliput 7" but cheaper with a decent resolution actual 2400x480 pixels.
and i will build it with 2 mirrors one being the cold version to help reduce heat. with some of that IR sheeting ( food for thought - possible that sheeting from car window tinting may do the same job.)
i particularly like this guys design http://www.thegarage.cjb.net/
but with 2 mirrors - he has one mirror . and more specific the lighting arrangement and cost with regards to replcament globes at $95 AUD for 10,000 hrs thats less than 1cent per hour at 250watt,which should be bright enough.
although i particularly like the idea of trying one of these setups. it would be simply unique its a xga resolution screen 0.9" LCOS microdisplay. found here http://www.tmdc.com.tw/images/tmdc XGV0901specificationDM.pdf
love to hear your comments on this
regards tony
little tiny LCDs
Keep in mind that those 0.9" LCDs are black & white, so you would need three of them with color filters and a beam combiner or three projection lenses to make a color image. Also they are reflective, so you would have to bounce the light off them instead of passing it through like most DIY projectors.
And finally: I think you would also have a terrible overheating problem. All of that light being absorbed by the LCD in an area less than 1 square inch, is just asking for a meltdown!
Keep in mind that those 0.9" LCDs are black & white, so you would need three of them with color filters and a beam combiner or three projection lenses to make a color image. Also they are reflective, so you would have to bounce the light off them instead of passing it through like most DIY projectors.
And finally: I think you would also have a terrible overheating problem. All of that light being absorbed by the LCD in an area less than 1 square inch, is just asking for a meltdown!
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