I was thinking about the light that I'll use in the projector I'm building, and I had an idea. It doesn't seem like it would work to me, but I don't know why not. So I'd like some input.
Say you took apart the monitor, but left that white peice of plastic from the backlight behind the LCD panel. Then you just put in a few of those fluorex lightbulbs, or some other bright fluorescent lights behind it. Sort of making a super backlight. Then you only put one fresnell lens in front of the panel and the projection lens like normal. Why wouldn't that work?
Say you took apart the monitor, but left that white peice of plastic from the backlight behind the LCD panel. Then you just put in a few of those fluorex lightbulbs, or some other bright fluorescent lights behind it. Sort of making a super backlight. Then you only put one fresnell lens in front of the panel and the projection lens like normal. Why wouldn't that work?
I wouldnt waste my time with that. Those lights are not nearly bright enough for a decent projection. Just go with what works. There's no need to go with a new idea. Metal halide works great.
i disagree with tthat statement. whats wrong with experimenting. if you have the time and the money have some fun and experiment
hehe I'll be diplomatic and agree with both of you fellas ;-p I wouldn't waste time or money on the fluorescent lights as mccamp said "Those lights are not nearly bright enough for a decent projection." True to part2wanksta DIY is all about some fun and experimenting, and possibly comming up with something new and useable in the DIY community, maybe even claiming a 'Little bit of fame' for an idea would always be cool *wink*. I guess part of the process of comming up with ideas is also puting them forward to others for their input on the feasability of an idea which is what Carlofet has done 🙂 There will always be someone that has a laugh or shakes their head at certain ideas, I bet the Wright Brothers had many people snicker at them when attempting to soar like an eagle way back when lol Now Carlofet go get yaself a metal halide and figure a way out to cool the ******s better !!! lol
I never said experimenting was bad, just that that idea is not worth the time and money to experiemtn because it simply wouldnt be worth it. Experimenting should start from an idea that has potential. But if you want to do it, there is absolutely nothig wrong with that.
Take care
Take care
Re
Respectfully, I disagree that they do not have the light output....Watts vs lumens they aren't that far behind HIDs. The issue is that CFL's produce thier light by exciting the gasses in a large tube or network there of. The light is produced over a large area rather than from a single relatively smaller intense point source like a HID. The challenge is to figure out how to harness the light output of the CFL into usefull light.
I am playing around with them right now. I have a thread in the Lighting forum discussing my results thus far.
Respectfully, I disagree that they do not have the light output....Watts vs lumens they aren't that far behind HIDs. The issue is that CFL's produce thier light by exciting the gasses in a large tube or network there of. The light is produced over a large area rather than from a single relatively smaller intense point source like a HID. The challenge is to figure out how to harness the light output of the CFL into usefull light.
I am playing around with them right now. I have a thread in the Lighting forum discussing my results thus far.
I'd agree that the flourescent has the potential light output. 40W into a flourescent tube puts out a lot of light, but it's not a point source, which is good if you want relatively shadow-free light in a room, but not so great if you want a nice sharp projection.
The "super backlight" idea could work, but you'll need a lot of light to make up for the fact that you're using a diffuser, which will remove a lot of light from the equation. At a guess, I'd say you're looking at the approximate equivalent of 6-8 48" flourescent tubes to produce enough light, and you still need to direct it to the right place. Perhaps putting the lights into a box paneled on the inside with mirrors, so that the only way out is where you want it, but even that is of limited efficiency.
Of course this is also going to depend on the amount of ambient light, and the quality of the lens, as well as the screen material...
What I can't see a way around is that this is going to need to be BIG.
The "super backlight" idea could work, but you'll need a lot of light to make up for the fact that you're using a diffuser, which will remove a lot of light from the equation. At a guess, I'd say you're looking at the approximate equivalent of 6-8 48" flourescent tubes to produce enough light, and you still need to direct it to the right place. Perhaps putting the lights into a box paneled on the inside with mirrors, so that the only way out is where you want it, but even that is of limited efficiency.
Of course this is also going to depend on the amount of ambient light, and the quality of the lens, as well as the screen material...
What I can't see a way around is that this is going to need to be BIG.
A compact fluorescent might work....
Compact high output flourescent light, self-ballasted, fits into a standard usa light socket.
CF105 - 105W CFL SUPER BRIGHT
Item
Quantity Price
1 - 5 $ 29.95
6 + $ 27.95
In Stock & Ready To Ship
Specification Value
Lamp Type CMPCT FLRSNT
Base Type MEDIUM
Volts 120
Watts 105
Lumens 6720
Color Temp 6500
Rated Life (hrs) 10000
Max. Length (in) 12"
http://www.topbulb.com/find/Product_Description.asp_Q_intProductID_E_49655
T.
Compact high output flourescent light, self-ballasted, fits into a standard usa light socket.
CF105 - 105W CFL SUPER BRIGHT
Item
Quantity Price
1 - 5 $ 29.95
6 + $ 27.95
In Stock & Ready To Ship
Specification Value
Lamp Type CMPCT FLRSNT
Base Type MEDIUM
Volts 120
Watts 105
Lumens 6720
Color Temp 6500
Rated Life (hrs) 10000
Max. Length (in) 12"
http://www.topbulb.com/find/Product_Description.asp_Q_intProductID_E_49655
T.
Re: A compact fluorescent might work....
it has been tried and failed ( many times ). if you like, you can go back to a post aroud end of year 2003 (2002 maybe?). It actually shown the picture of bulb assemly and failed result.
a rule of thumb, if you are using a projection lens which size is smaller than your LCD screen, you need a "point" light source and fresnel lens.
but if you are using a 5" PS1 LCD (or similar ) and a CRT projection lens ( normally are 4 1/2 " and above ) you can PROBABLY use flourenscent lights.
it has been tried and failed ( many times ). if you like, you can go back to a post aroud end of year 2003 (2002 maybe?). It actually shown the picture of bulb assemly and failed result.
a rule of thumb, if you are using a projection lens which size is smaller than your LCD screen, you need a "point" light source and fresnel lens.
but if you are using a 5" PS1 LCD (or similar ) and a CRT projection lens ( normally are 4 1/2 " and above ) you can PROBABLY use flourenscent lights.
tgreenwood said:
That bulbs ****, a CDM-T puts out 12500lm on average and its 150w. Its also a point source with an arc that HAS INTENSITY!!! (thats what you need mainly before anything to bring the colours out).
Im suprised this idea gets brought up over and over again. If only if you guys searched you would soon see that this floresent light source has been tried and used widely 3years back and the results wearnt that good. Thats why we use Metal Halide today.
A flouresent bulb at 105w also dont run that cool, they are also a killer uv sorce. Question yourself this: Why dont the pro's use them?
Trev🙂
Im suprised this idea gets brought up over and over again. If only if you guys searched you would soon see that this floresent light source has been tried and used widely 3years back and the results wearnt that good. Thats why we use Metal Halide today.
A flouresent bulb at 105w also dont run that cool, they are also a killer uv sorce. Question yourself this: Why dont the pro's use them?
Trev🙂
Well Ace, that is a question that has been going through my head too. I dont mind MH in a commercial setting but I'm leery about playing with x000volt arc sources in my house.
This is what went through my head:
Traditional movie theatres use Xenon point arcs. Very bright, good white temp, highly colaminated - which is important for blurr and ghosting with a small 35mm film
Commercial digital projectors use MH. Good efficiency and temp. One bulb setup is compact. Point source.
What Im trying as a project: multi-bulb with all consumer grade items. 15" LCD 1024x768, OHP lenses and mirror. The point of the difference is not "because it's there" but to counter a shortcomming of a point source with a big LCD. Uneven lighting. I think colamination is not as big an issue for LCD as it is for film so I dont mind useing multi-point sources to have even light intensity across my screen. This is really for proof of concept for a future HDTV resolution setup. Im sure THAT LCD will be big and one bulb will bloom in the middle with weak lighting around the edges. Fresnels will only go so far. Intensity drops at the square of distance from the source and the edges of the LCD (or fresnel)plane have to be further away from the source.
I dont mind useing a series of microdiffusers to create an even high intensity light plane. I think lcd needs raw, even lumens and the colamination issue is secondary with a high quality microdiffuser directly under the LCD. I may prove myself wrong. It could be that multi-points with approximate ray covergence will blurr out. I have thought about taking laser colamination technology for the fresnel point but that gets big. Hopefully an even lightbox with enough intensity will do the trick.
This is probably why everyone keeps returning to these kind of solutions. Having a multi-socket solution that anyone could open to change a standard bulb is where its at in the future.
This is what went through my head:
Traditional movie theatres use Xenon point arcs. Very bright, good white temp, highly colaminated - which is important for blurr and ghosting with a small 35mm film
Commercial digital projectors use MH. Good efficiency and temp. One bulb setup is compact. Point source.
What Im trying as a project: multi-bulb with all consumer grade items. 15" LCD 1024x768, OHP lenses and mirror. The point of the difference is not "because it's there" but to counter a shortcomming of a point source with a big LCD. Uneven lighting. I think colamination is not as big an issue for LCD as it is for film so I dont mind useing multi-point sources to have even light intensity across my screen. This is really for proof of concept for a future HDTV resolution setup. Im sure THAT LCD will be big and one bulb will bloom in the middle with weak lighting around the edges. Fresnels will only go so far. Intensity drops at the square of distance from the source and the edges of the LCD (or fresnel)plane have to be further away from the source.
I dont mind useing a series of microdiffusers to create an even high intensity light plane. I think lcd needs raw, even lumens and the colamination issue is secondary with a high quality microdiffuser directly under the LCD. I may prove myself wrong. It could be that multi-points with approximate ray covergence will blurr out. I have thought about taking laser colamination technology for the fresnel point but that gets big. Hopefully an even lightbox with enough intensity will do the trick.
This is probably why everyone keeps returning to these kind of solutions. Having a multi-socket solution that anyone could open to change a standard bulb is where its at in the future.
fluorescents less efficient than MH
I don't know why everybody assumes that fluorescents are "cooler" that MH bulbs. The numbers are widely available!
Even the best CCFL fluorescents only put out 50 lumens per Watt. Normal fluorescent bulbs are even lower. Common MH bulbs put out 82-85 lumens per Watt. So you will have to use more Watts of fluorescents to get the same number of lumens, and all of that power that is not coming out as light will come out as heat instead.
And that has been the experience of everybody who has put enough Watts of fluorescents inside a projector: "Surprising amount of heat!"
When you add up how many fluorescents and individual ballasts you will need, they cost more than a single MH and ballast. Since you need more Watts to get the same amount of light as the MH, they would also cost more to run.
So what is the advantage of using fluorescent lamps over MH?
I don't know why everybody assumes that fluorescents are "cooler" that MH bulbs. The numbers are widely available!
Even the best CCFL fluorescents only put out 50 lumens per Watt. Normal fluorescent bulbs are even lower. Common MH bulbs put out 82-85 lumens per Watt. So you will have to use more Watts of fluorescents to get the same number of lumens, and all of that power that is not coming out as light will come out as heat instead.
And that has been the experience of everybody who has put enough Watts of fluorescents inside a projector: "Surprising amount of heat!"
When you add up how many fluorescents and individual ballasts you will need, they cost more than a single MH and ballast. Since you need more Watts to get the same amount of light as the MH, they would also cost more to run.
So what is the advantage of using fluorescent lamps over MH?
Re
I just finished testing several configurations using 20watt 65K ccfl's (1100 lux), 5" psone (VERTEK GC Version) and a crt lens.
My results, I first tried the back light method. the problem here is that you have a very bright non point source of light, that simply won't push the light through the LCD well. especially since we are reversing the lcd. I got a very dim image.
Next I tried building mirror box, and got similar results.
My next attempt was cutting up an shop light reflector can and reforming it into a large parabolic refllector. I only used a single lamp and got much better results almost double the brightness.
So I decided that I really need to build a reflector that will harness the light and put it in the direction I need it. I decided I wanted to use 2 of the 20 wattt ccfl's So I sat down and drew out several reflectors to map out how the light will react, really the most important thing is to figure out how to place the lamp in the reflector to utilize all the lamps light and push it foreard where it can be collimated by a frenzel. So I made up a template and fabricated up some galvanized sheet metal then polished it up. This is what it kind of looks like.
With 40 watts I am pretty surprised at the results, I would say maybe 80-100 lumens brightness. Not nearly enough for a home theater, but on a high gain screen definiatly enough for the kids play room. I agree that 6500k is probably too high a color temp. I would say need 4100-5000K for this LCD. I can run this thing completely closed up with no fan for over an hour with no heat issues. though the steel fabricated reflector does dissipate the heat kind of like a heat sink. I will still put an exhaust fan in better safe than sorry. Also each separator in the assemble is really a channel with tops and bottoms open for circulating air accross the lenses and the LCD.
I will create a thread for my build, when I complete the audio circuits and fit and finish.
I will say that I was very pleased by the results with 2 20watt bulbs. I have three crt lenses, so I can see several variations and tests coming...
I would also say that a 70watt metal halide would yield pretty darn good results maybe 300-400+ lumens based on the overall efficiency of a setup like this. I think that is probably the most efficient way to go for a low wattage setup, however for 16bucks CCFL's ain't so bad....lol
I just finished testing several configurations using 20watt 65K ccfl's (1100 lux), 5" psone (VERTEK GC Version) and a crt lens.
My results, I first tried the back light method. the problem here is that you have a very bright non point source of light, that simply won't push the light through the LCD well. especially since we are reversing the lcd. I got a very dim image.
Next I tried building mirror box, and got similar results.
My next attempt was cutting up an shop light reflector can and reforming it into a large parabolic refllector. I only used a single lamp and got much better results almost double the brightness.
So I decided that I really need to build a reflector that will harness the light and put it in the direction I need it. I decided I wanted to use 2 of the 20 wattt ccfl's So I sat down and drew out several reflectors to map out how the light will react, really the most important thing is to figure out how to place the lamp in the reflector to utilize all the lamps light and push it foreard where it can be collimated by a frenzel. So I made up a template and fabricated up some galvanized sheet metal then polished it up. This is what it kind of looks like.
An externally hosted image should be here but it was not working when we last tested it.
With 40 watts I am pretty surprised at the results, I would say maybe 80-100 lumens brightness. Not nearly enough for a home theater, but on a high gain screen definiatly enough for the kids play room. I agree that 6500k is probably too high a color temp. I would say need 4100-5000K for this LCD. I can run this thing completely closed up with no fan for over an hour with no heat issues. though the steel fabricated reflector does dissipate the heat kind of like a heat sink. I will still put an exhaust fan in better safe than sorry. Also each separator in the assemble is really a channel with tops and bottoms open for circulating air accross the lenses and the LCD.
I will create a thread for my build, when I complete the audio circuits and fit and finish.
I will say that I was very pleased by the results with 2 20watt bulbs. I have three crt lenses, so I can see several variations and tests coming...
I would also say that a 70watt metal halide would yield pretty darn good results maybe 300-400+ lumens based on the overall efficiency of a setup like this. I think that is probably the most efficient way to go for a low wattage setup, however for 16bucks CCFL's ain't so bad....lol
Just wanted to share this info I found today.
This is a new compact fluorescent which has 9000 lumens output
I have no idea how much they cost and currently I have no intention to try them out.
But if you are one of those currenly using a compact fluorescent or thinking of trying then this maybe of interest, the lights are from Phillips the link below.
The lamps are PHILLIPS MASTER PL-H lamps 120W 9000 lumens 73lumens/watt 4000K 10,000hrs
http://www.lighting.philips.com/in_...main=gb_en&parent=1_2_1&id=in_en_pl_h&lang=en
This is a new compact fluorescent which has 9000 lumens output
I have no idea how much they cost and currently I have no intention to try them out.
But if you are one of those currenly using a compact fluorescent or thinking of trying then this maybe of interest, the lights are from Phillips the link below.
The lamps are PHILLIPS MASTER PL-H lamps 120W 9000 lumens 73lumens/watt 4000K 10,000hrs
http://www.lighting.philips.com/in_...main=gb_en&parent=1_2_1&id=in_en_pl_h&lang=en
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