Has anyone experimented with using multiple compact fluoros and a flat white diffuser to illuminate an lcd. I am thinking along the lines of CRT here. I have a crt projector, and an extra set of 8" lenses.
CRT's are relatively not that bright. My thought is if you could generate an even very bright back light using a flat white back panel (diffuser) with four surrounding 6500k 23 watt cfl's. then use a frenzel to focus the light then put a 8" crt lense infront of the panel very close like a crt. CFL's are approx 1500 lumens each. 6000 total * .50 * .79 * .15 = 337.5 Lumens at the lense. (that is just an estimation, of losses through the components.)
I dunno if it would work, but I think it might. Maybe even upping the wattage of the bulbs. Flourex 65 watters put out alot of lumens (8000 or so).
I was just wondering if anyone has experimented with such a set up, so I can gain some knowledge prior to wasting my time...lol. What will my design challenges be?
JR
CRT's are relatively not that bright. My thought is if you could generate an even very bright back light using a flat white back panel (diffuser) with four surrounding 6500k 23 watt cfl's. then use a frenzel to focus the light then put a 8" crt lense infront of the panel very close like a crt. CFL's are approx 1500 lumens each. 6000 total * .50 * .79 * .15 = 337.5 Lumens at the lense. (that is just an estimation, of losses through the components.)
I dunno if it would work, but I think it might. Maybe even upping the wattage of the bulbs. Flourex 65 watters put out alot of lumens (8000 or so).
I was just wondering if anyone has experimented with such a set up, so I can gain some knowledge prior to wasting my time...lol. What will my design challenges be?
JR
I once tried 3 fluorex lamps with an 8" panel. The surprising part was the amount of heat generated. Projected image did not meet my criteria for projection with lights on.
Ive got a 3M 1810 @ 2500 lumens. Its cool and quiet as advertised and does work with my Benq 531 panel. The problem is its not bright enough. I got the same idea as the guy in this thread:
Increase the lumens with 3 - 23Watt CF bulbs (150 watt equivalent = 1450 lumens each) in the enclosure. I am using the clip on bulb contraptions with the reflective cone from the hardware store. I figure I can shine the main bulb through the middle with the 3 CFs slightly off angle pointing at the freznel. Kind of a semetric flower pattern. Or maybe point them all at a mirror pointing at the freznel to reduce the beam spread.
Im not sure why people are talking about a point source. wouldnt that make the middle of the 15" LCD brighter than the rest? Dont you want even luminocity across the whole LCD? Wouldnt a white defuser under the fesnels help with this?
Please explain.
Increase the lumens with 3 - 23Watt CF bulbs (150 watt equivalent = 1450 lumens each) in the enclosure. I am using the clip on bulb contraptions with the reflective cone from the hardware store. I figure I can shine the main bulb through the middle with the 3 CFs slightly off angle pointing at the freznel. Kind of a semetric flower pattern. Or maybe point them all at a mirror pointing at the freznel to reduce the beam spread.
Im not sure why people are talking about a point source. wouldnt that make the middle of the 15" LCD brighter than the rest? Dont you want even luminocity across the whole LCD? Wouldnt a white defuser under the fesnels help with this?
Please explain.
I built a light box this weekend, using 3 20watt 65k cfl's I put them in a box just larger than they are. I mounted a mirror behind the lamps as the back of the box. I also dissasembeld the lamps and removed the ballasts to make the box more compact. I originally figured there is maybe 50% usable light.
I tested it on my ps1/crt lense projector I am building. There are a couple of issues.
1. light loss in the box. Inherently light coming from a CFL is not directional very "scattered" if you will. I remeber on another board dicusion about a light source ability to penatrate and hid's have a very intense point source, where as cfl's iluminate a large area of phosphor in a tube. So maybe there is 30-40% of the light coming out of the box and the rest is wasted light it is extremely scattered.
2. Heat is a another issue the box gets pretty hot. I used a light diffuser from an old laptop LCD and I was afraid it was going to melt. I don't think it can be as close to the LCD as it needs to be to be effective in this configuration.
My results....Well the jury is still out, I am gonna test a few more configurations I was able to get a relatively low level through the LCD. It may be a watchable picture on a screen, but needs to be about twice as bright. I would say maybe 50-100 lumens @ 48" 150-250 is my goal.
I am gonna try two cfl's and see if I can improve the efficiency of the light box. Maybe use reflectors in a batwing config instead of the mirror to get more light where I want it.
I tested it on my ps1/crt lense projector I am building. There are a couple of issues.
1. light loss in the box. Inherently light coming from a CFL is not directional very "scattered" if you will. I remeber on another board dicusion about a light source ability to penatrate and hid's have a very intense point source, where as cfl's iluminate a large area of phosphor in a tube. So maybe there is 30-40% of the light coming out of the box and the rest is wasted light it is extremely scattered.
2. Heat is a another issue the box gets pretty hot. I used a light diffuser from an old laptop LCD and I was afraid it was going to melt. I don't think it can be as close to the LCD as it needs to be to be effective in this configuration.
My results....Well the jury is still out, I am gonna test a few more configurations I was able to get a relatively low level through the LCD. It may be a watchable picture on a screen, but needs to be about twice as bright. I would say maybe 50-100 lumens @ 48" 150-250 is my goal.
I am gonna try two cfl's and see if I can improve the efficiency of the light box. Maybe use reflectors in a batwing config instead of the mirror to get more light where I want it.
CFs are difuse light but you already know how to solve that problem: Fresnels.
Buy a mirror from a glass shop and get a glass cutter and silicone. Make a mirror box (angled walls) for each CF and put a fresnel on top to focus all the light coming out of the box. Repeat several times.
Make a box that angles all the focused light on a concave "vanity" type mirror. It doesnt have to be optically precise it is collecting several light sources and aligning the light to a point. use a fresnel to open the point to a plane of colinear light.
I am setting up about 6000 lumens in this manner with about 100Watts power used. I can add more lights if i wish. Also the light temp is right and its not dangerous like metal halide - no chance of fire, exploding bulb or UV burn. 😎
I have a serious problem with the idea of high current draw in my house. Firing up a MH could make the wall wiring hot enough to catch fire. Im in an old building with aluminum wire. No chance im using MH.
I dont want to pay that kind of electricity bill either.
The only problem with this setup is that its bigger than a one bulb setup.
Buy a mirror from a glass shop and get a glass cutter and silicone. Make a mirror box (angled walls) for each CF and put a fresnel on top to focus all the light coming out of the box. Repeat several times.
Make a box that angles all the focused light on a concave "vanity" type mirror. It doesnt have to be optically precise it is collecting several light sources and aligning the light to a point. use a fresnel to open the point to a plane of colinear light.
I am setting up about 6000 lumens in this manner with about 100Watts power used. I can add more lights if i wish. Also the light temp is right and its not dangerous like metal halide - no chance of fire, exploding bulb or UV burn. 😎
I have a serious problem with the idea of high current draw in my house. Firing up a MH could make the wall wiring hot enough to catch fire. Im in an old building with aluminum wire. No chance im using MH.
I dont want to pay that kind of electricity bill either.The only problem with this setup is that its bigger than a one bulb setup.
This should help you get more useful light out of your setup:
http://products3.3m.com/catalog/us/...ikuiti_3_0/command_AbcPageHandler/output_html
Note that a metalic reflector will not randomise the polarisation so those setups cant take advantage of the film. their plastic reflector film (>98% reflectivity )however will work as will any mylar I assume.
You could use an easily workable material to shape a parabola and coat the inside with the reflector film. This would be smokin efficient with CF bulbs but just smoke with MH bulbs
http://products3.3m.com/catalog/us/...ikuiti_3_0/command_AbcPageHandler/output_html
Note that a metalic reflector will not randomise the polarisation so those setups cant take advantage of the film. their plastic reflector film (>98% reflectivity )however will work as will any mylar I assume.
You could use an easily workable material to shape a parabola and coat the inside with the reflector film. This would be smokin efficient with CF bulbs but just smoke with MH bulbs
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