Additional information about 4-pack xenons: You can find it at the above link and then click 'Beleuchtung', which means lighting.
BTW. this is the last single panel projector i know built up to now. GP-elektonik also builts another type, the GP Movin 2002 with a 4-pack of 4x50 Watts.
I don't know much about the exact optical design, but i suppose, if these xenons have parabolic reflectors, they send parallel rays, which are collimated right before they go through the panel, or direct after panel.
xblocker
BTW. this is the last single panel projector i know built up to now. GP-elektonik also builts another type, the GP Movin 2002 with a 4-pack of 4x50 Watts.
I don't know much about the exact optical design, but i suppose, if these xenons have parabolic reflectors, they send parallel rays, which are collimated right before they go through the panel, or direct after panel.
xblocker
I dont understand how a 175W bulb puts out 60,000 lumens. Thats 342.8 lumens per watt, about 3 times the efficiency of the highest efficiency Metal Halide bulb that I have seen.
Researching...
a ha. here we go.
http://www.lighting.philips.com/nam/product_database/hid/displayhid.php?id=124
Watts: 175
Bulb: PAR-38
Base: Med.
Ordering Code: MH175/RSP
ANSI Code/Ballast Ref.: M57/E
Description: †G, Clear, 16 degree Beam
M.O.L. (in.): 5 13/16
Rated Avg. Life Hrs.: 7500
Approximate Mean Lumens: N/A
Approximate Initial Lumens: 60,000 MBCP
CRI: 65
CCT (K): 4100
That site has the specs listed wrong. It is NOT lumens. It is MBCP, a candlepower rating. I would be highly, highly suspicious about purchasing this bulb! I can nearly guarantee you that it won't be bright enough. The *only* thing going for it is that it has a reflector built in. The reason why the candlepower rating is so darn high, is that the beam that this bulb puts off is only 16 degrees.
looking, I see that philips makes another 175W Metal Halide PAR 38, that puts out a 65 degree beam, MH175/RFL
Watts: 175
Bulb: PAR-38
Base: Med.
Product Number: 046677-30858-5
Ordering Code: MH175/RFL
ANSI Code/Ballast Ref.: M57/E
Package Quantity: 6
Description: †G, Clear, 65 degree Beam
M.O.L. (in.): 5 13/16
L.C.L. (in.): N/A
Rated Avg. Life Hrs.: 7500
Approximate Mean Lumens: N/A
Approximate Initial Lumens: 10,000 MBCP
CRI: 65
CCT (K): 4100
As you can see, the changing of the beam from 16 degrees to 65 degrees has taken the MBCP from 60,000 to 10,000.
The efficiency of this bulb is more than likely no more than any other bulb, and, it probably actually puts out at the most, 175*100 = 17,500 lumens. The thing that is cool is that it is extremely efficiently used. But, I still have my doubts.
Researching...
a ha. here we go.
http://www.lighting.philips.com/nam/product_database/hid/displayhid.php?id=124
Watts: 175
Bulb: PAR-38
Base: Med.
Ordering Code: MH175/RSP
ANSI Code/Ballast Ref.: M57/E
Description: †G, Clear, 16 degree Beam
M.O.L. (in.): 5 13/16
Rated Avg. Life Hrs.: 7500
Approximate Mean Lumens: N/A
Approximate Initial Lumens: 60,000 MBCP
CRI: 65
CCT (K): 4100
That site has the specs listed wrong. It is NOT lumens. It is MBCP, a candlepower rating. I would be highly, highly suspicious about purchasing this bulb! I can nearly guarantee you that it won't be bright enough. The *only* thing going for it is that it has a reflector built in. The reason why the candlepower rating is so darn high, is that the beam that this bulb puts off is only 16 degrees.
looking, I see that philips makes another 175W Metal Halide PAR 38, that puts out a 65 degree beam, MH175/RFL
Watts: 175
Bulb: PAR-38
Base: Med.
Product Number: 046677-30858-5
Ordering Code: MH175/RFL
ANSI Code/Ballast Ref.: M57/E
Package Quantity: 6
Description: †G, Clear, 65 degree Beam
M.O.L. (in.): 5 13/16
L.C.L. (in.): N/A
Rated Avg. Life Hrs.: 7500
Approximate Mean Lumens: N/A
Approximate Initial Lumens: 10,000 MBCP
CRI: 65
CCT (K): 4100
As you can see, the changing of the beam from 16 degrees to 65 degrees has taken the MBCP from 60,000 to 10,000.
The efficiency of this bulb is more than likely no more than any other bulb, and, it probably actually puts out at the most, 175*100 = 17,500 lumens. The thing that is cool is that it is extremely efficiently used. But, I still have my doubts.
For instance, here is another Metal Halide bulb I found on philips' site.
Description: †G, PAR WISO Spot 15 degrees FadeBlock 54,000 MBCP
Rated Avg. Life Hrs.: 10,000
Approximate Mean Lumens: 4800
Approximate Initial Lumens: 6000
It is a 100W PAR38 that puts out a 15 degree beam, and 54,000 MBCP. Its actual rated lumens, however, is only 6,000!!!!!!!!!!!!!!
CRAPPY, I SAY! hehe.
Description: †G, PAR WISO Spot 15 degrees FadeBlock 54,000 MBCP
Rated Avg. Life Hrs.: 10,000
Approximate Mean Lumens: 4800
Approximate Initial Lumens: 6000
It is a 100W PAR38 that puts out a 15 degree beam, and 54,000 MBCP. Its actual rated lumens, however, is only 6,000!!!!!!!!!!!!!!
CRAPPY, I SAY! hehe.
Xblocker,
You are a star!!!
Awesome!!! You have opened SO many doors with this find!!!
The fact that miltiple light sources can be used like this without needing to simulate a single point source has SIGNIFICANT implications for everybody to think about, because no matter how good the reflectors are, this arrangement can not produce a single perfectly parallel beam without a significant degree of scattering.
As you mention, some fresnel must be used either in front or behind the panel to cause the emerging light from the LCD to converge on the Objective.
But, whether the fresnel is in front or behind the LCD now has important implications regarding whether it is more important to treat the LCD as a an optical filter in a longer optical pipeline, or, treat it as a completely independent light source itself: a light source whose properties are determined by the evenness of it's back illumination, and the panel's efficiency in using that illumination to produce its image (polarised illuminating light perpendicular to the LCD surface, being the optimal arrangement).
The first thing that triggered me into not accepting the optical pipeline theory, was the original working projector produced by Zark - using LOA bulbs to illuminate a small(ish) LCD panel, and feeding into a Rear Projection TV Lens.
http://www.geocities.com/zark5150/projpicnew.html
It should not have worked at all with the diffuse light from the LOAs if the optical pipeline theory was necessary with LCD panels. (An optical pipeline WOULD still work, but it would not be the only option...)
Anyway, whatever, this find will definitely provoke new research, and could propell everybody to the next level! (Nice, small, light, bright and cheap!!!)
Unfortunately, my subsequent research into these Xenon HID bulbs indicates problems for us in using them: Despite their EXCEPTIONAL price, unless their ignitor and possibly their ballast is included, the total package could become expensive...
Each bulb would need its own ignitor module, and almost certainly its own ballast too.
The best prices I have seen for these ballasts in the US is around $100 each. For four bulbs, this gets a little expensive...
However, what is MOST valuable to me from this is that the TFT LCDs do not need to be driven from a light source that emulates a single point of light...
Interesting...
Bill.
You are a star!!!
Awesome!!! You have opened SO many doors with this find!!!The fact that miltiple light sources can be used like this without needing to simulate a single point source has SIGNIFICANT implications for everybody to think about, because no matter how good the reflectors are, this arrangement can not produce a single perfectly parallel beam without a significant degree of scattering.
As you mention, some fresnel must be used either in front or behind the panel to cause the emerging light from the LCD to converge on the Objective.
But, whether the fresnel is in front or behind the LCD now has important implications regarding whether it is more important to treat the LCD as a an optical filter in a longer optical pipeline, or, treat it as a completely independent light source itself: a light source whose properties are determined by the evenness of it's back illumination, and the panel's efficiency in using that illumination to produce its image (polarised illuminating light perpendicular to the LCD surface, being the optimal arrangement).
The first thing that triggered me into not accepting the optical pipeline theory, was the original working projector produced by Zark - using LOA bulbs to illuminate a small(ish) LCD panel, and feeding into a Rear Projection TV Lens.
http://www.geocities.com/zark5150/projpicnew.html
It should not have worked at all with the diffuse light from the LOAs if the optical pipeline theory was necessary with LCD panels. (An optical pipeline WOULD still work, but it would not be the only option...)
Anyway, whatever, this find will definitely provoke new research, and could propell everybody to the next level! (Nice, small, light, bright and cheap!!!)
Unfortunately, my subsequent research into these Xenon HID bulbs indicates problems for us in using them: Despite their EXCEPTIONAL price, unless their ignitor and possibly their ballast is included, the total package could become expensive...
Each bulb would need its own ignitor module, and almost certainly its own ballast too.
The best prices I have seen for these ballasts in the US is around $100 each. For four bulbs, this gets a little expensive...
However, what is MOST valuable to me from this is that the TFT LCDs do not need to be driven from a light source that emulates a single point of light...
Interesting...
Bill.
Undream,
You are definitely correct in calling the 6000 lumen output from the 175 Watt bulb crappy compared to the 400 Watt beasts.
However, the seemingly accepted efficiency of the LCD panels we are using here is around 10%.
If these bulbs are well focussed and all of the 6000 lumens comes out of the front (unlike most of the designs using the 400Watt bulbs), then with just 10% efficiency in the LCD, we would get 600 lumens coming through the panel...
If we do a cross of Zark's LOA design with the light unit found by Xblocker, and have just two of these bulbs shining through the LCD panel, and pointing towards the objective, then who is to say that the results wouldn't be fantastic???
(I would still shine the bulbs directly at the panel, and put a fresnel between the panel and the objective, but then I am a psycho!!! )
Bill.
You are definitely correct in calling the 6000 lumen output from the 175 Watt bulb crappy compared to the 400 Watt beasts.
However, the seemingly accepted efficiency of the LCD panels we are using here is around 10%.
If these bulbs are well focussed and all of the 6000 lumens comes out of the front (unlike most of the designs using the 400Watt bulbs), then with just 10% efficiency in the LCD, we would get 600 lumens coming through the panel...
If we do a cross of Zark's LOA design with the light unit found by Xblocker, and have just two of these bulbs shining through the LCD panel, and pointing towards the objective, then who is to say that the results wouldn't be fantastic???
(I would still shine the bulbs directly at the panel, and put a fresnel between the panel and the objective, but then I am a psycho!!!
) Bill.
Hey, I have a question about this auction:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2037292345
How in god's name did this auction for 2 Sharp QA-50s get to 255 dollars? I thought that those were grayscale panels. Who would pay that much for those things?
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2037292345
How in god's name did this auction for 2 Sharp QA-50s get to 255 dollars? I thought that those were grayscale panels. Who would pay that much for those things?
Refering again to this xenon lights: Such a design can only work, if real parallelbeams come out of the box. So if someone has now the idea to try a similar arrangement with common cold light mirror halogen lamps or other non parallel lightsources,this might not work, 'cause these have a certain flood angle and a single condensor can't them fit together!
Also brightness isn't kickass, the 'Movin' projectors only reach 200-250 ANSIlumen, although a contrast ratio of 500:1. How they do this ? I don't know. Heard something about a second shutter panel, but no facts here..
xblocker
Also brightness isn't kickass, the 'Movin' projectors only reach 200-250 ANSIlumen, although a contrast ratio of 500:1. How they do this ? I don't know. Heard something about a second shutter panel, but no facts here..
xblocker
Xblocker,
But the beams coming out of these things CAN'T be perfectly parallel - the HID bulbs don't have a point source spark gap, and the the way the parabolic reflectors are arranged, there will be significant light reaching the (1 st) panel directly from all four bulbs.
I like the thing about using two panels, though - that would definitely eliminate most interference from non parallel light...
VERY interesting...
But... More questions:
1) What about the Zark design? Was it ultimately found not to work? (He seemed to use a large CRT lens, and that could have some bearing on this...)
2) How do the CRT projectors produce a viable image when a CRT tube DEFINITELY produces a diffuse image?
I still think the LCD panel should be treated as the light source by the optics that follow...
If you can explain where I am wrong, I would sincerely appreciate it!!!
Thanks,
Bill.
P.S. Most car Xenon HID bulbs seem to give 3000 lumens from 35 Watts. 4x3000=12000. This means that the efficiency of their system is higher than I would have expected...
But the beams coming out of these things CAN'T be perfectly parallel - the HID bulbs don't have a point source spark gap, and the the way the parabolic reflectors are arranged, there will be significant light reaching the (1 st) panel directly from all four bulbs.
I like the thing about using two panels, though - that would definitely eliminate most interference from non parallel light...
VERY interesting...
But... More questions:
1) What about the Zark design? Was it ultimately found not to work? (He seemed to use a large CRT lens, and that could have some bearing on this...)
2) How do the CRT projectors produce a viable image when a CRT tube DEFINITELY produces a diffuse image?
I still think the LCD panel should be treated as the light source by the optics that follow...
If you can explain where I am wrong, I would sincerely appreciate it!!!
Thanks,
Bill.
P.S. Most car Xenon HID bulbs seem to give 3000 lumens from 35 Watts. 4x3000=12000. This means that the efficiency of their system is higher than I would have expected...
Hay guys,
I'm still here!
I read this (part I and part II) and have kept up with it for months.
A few thing I have found (correct me if I wrong)
We need a light with low heat and high output....
Talked to a guy at a Lighting store and we have a few problems with what is available... heat, life of the bulb (that is capable of producing the output we need), size, and reliable and consistent color temperature.
I have to agree that to date it seems that the 400 watt mh is the way to go. However it is far from perfect, it has several problems. The first is the mere size, this thing is really big (respectively), second the power it takes to run it (has anyone see their electric bill and have used this thing as a "main TV." I have not but it but am not looking forward to it. The third is the heat (not a BIG problem it seems) heat comes from the watts the higher the wattage the more heat ... 400 is some heat to deal with. I have a 500 watt halogen (it seems the halogens run hotter, but not confirmed) and, as said in an earlier post, it could also be used as slow roaster. The forth is the cost ($100 in just the light seems too much). The last two are important and have not been addressed, the mh bulb is not consistent in color (mostly over time), I believe that this bulb has not been used long enough (months, maybe even a year or so) to see how it will vary over time. The last is the start up time (time to get to maximum brightness). There are bulbs that have long life, are bright (when used in conjunction), are inexpensive, cooler, and have the correct color temp. The problem seems to be the distortion that mulitple bulb (or light sources cause).......
I don’t claim to be a genius in any way, but why could we not build a projector in a projector.... some thing like this....
I'm still here!
I read this (part I and part II) and have kept up with it for months.
A few thing I have found (correct me if I wrong)
We need a light with low heat and high output....
Talked to a guy at a Lighting store and we have a few problems with what is available... heat, life of the bulb (that is capable of producing the output we need), size, and reliable and consistent color temperature.
I have to agree that to date it seems that the 400 watt mh is the way to go. However it is far from perfect, it has several problems. The first is the mere size, this thing is really big (respectively), second the power it takes to run it (has anyone see their electric bill and have used this thing as a "main TV." I have not but it but am not looking forward to it. The third is the heat (not a BIG problem it seems) heat comes from the watts the higher the wattage the more heat ... 400 is some heat to deal with. I have a 500 watt halogen (it seems the halogens run hotter, but not confirmed) and, as said in an earlier post, it could also be used as slow roaster. The forth is the cost ($100 in just the light seems too much). The last two are important and have not been addressed, the mh bulb is not consistent in color (mostly over time), I believe that this bulb has not been used long enough (months, maybe even a year or so) to see how it will vary over time. The last is the start up time (time to get to maximum brightness). There are bulbs that have long life, are bright (when used in conjunction), are inexpensive, cooler, and have the correct color temp. The problem seems to be the distortion that mulitple bulb (or light sources cause).......
I don’t claim to be a genius in any way, but why could we not build a projector in a projector.... some thing like this....
Attachments
woneill,
i don't say you're wrong, i only would like bring some things to a point.
Exact parallel rays of course is only reachable in a mathematical sense, we can only get near as parallel. So the panel shouldn't be hit at the same area of beams of the other bulbs, paraxial rays should only 'touch' themselves at the outer areas of the beam.
CRT projection optics differ from other optics because, (i try to translate from german, grace!) CRTs are self lighting systems with a large luminance area, which indeed is a diffuse lightsource. Since CRT's brightness isn't so good, the optics must have an aperture as large as possible to catch a maximum of 'image' rays. Important: F-ratio of 1.0 is an optical limitation of objectives, the lens's diameter can't overgo focus length!
This is a classical optical system without condensors and should of course work with LCD panels too, if the sizes match together.
Working with a separate lightsource, you have 2 options:
a) backlight a panel with diffuse light and treat the whole thing like a CRT system.
b)collimate light with condensors through the panel, so that direct light goes through panel and objective. But you can design the beam going to the opjective, so that it hasn't to be so large.
As we all know, b) is the setup of most projectors 'cause it's much more effective.
Must light through LCD panel be parallel? Only if you have more then 1 lightsource (4 xenons). If you have only a single lightsource it isn't mandatory. My OHP+panel give good image. This point seems to be a little overestimated.
What Zark's setup concerns, i don't know much about anymore, saw so much pics over the months...sorry!
i don't say you're wrong, i only would like bring some things to a point.
Exact parallel rays of course is only reachable in a mathematical sense, we can only get near as parallel. So the panel shouldn't be hit at the same area of beams of the other bulbs, paraxial rays should only 'touch' themselves at the outer areas of the beam.
CRT projection optics differ from other optics because, (i try to translate from german, grace!) CRTs are self lighting systems with a large luminance area, which indeed is a diffuse lightsource. Since CRT's brightness isn't so good, the optics must have an aperture as large as possible to catch a maximum of 'image' rays. Important: F-ratio of 1.0 is an optical limitation of objectives, the lens's diameter can't overgo focus length!
This is a classical optical system without condensors and should of course work with LCD panels too, if the sizes match together.
Working with a separate lightsource, you have 2 options:
a) backlight a panel with diffuse light and treat the whole thing like a CRT system.
b)collimate light with condensors through the panel, so that direct light goes through panel and objective. But you can design the beam going to the opjective, so that it hasn't to be so large.
As we all know, b) is the setup of most projectors 'cause it's much more effective.
Must light through LCD panel be parallel? Only if you have more then 1 lightsource (4 xenons). If you have only a single lightsource it isn't mandatory. My OHP+panel give good image. This point seems to be a little overestimated.
What Zark's setup concerns, i don't know much about anymore, saw so much pics over the months...sorry!
Xblocker,
We are definitely on the same page now! All the statements I have ever made concerning fresnels (and BIG lenses) were due to my following option a). I use the fresnel a couple of inches after the panel to provide the large aperture for a compound objective.
Doing that, the prime quality needed of the light source became evenness of illumination rather than the perfect point emitter that is so hard to reproduce.
Unfortunately, I wasn't able to express myself very effectively - your English is better than mine!
Bill.
P.S. Somebody seems to have made me a prophet. Shouldn't they have alternative classifications such as "nuissance" and "pain in the a$$"...
We are definitely on the same page now! All the statements I have ever made concerning fresnels (and BIG lenses) were due to my following option a). I use the fresnel a couple of inches after the panel to provide the large aperture for a compound objective.
Doing that, the prime quality needed of the light source became evenness of illumination rather than the perfect point emitter that is so hard to reproduce.
Unfortunately, I wasn't able to express myself very effectively - your English is better than mine!
Bill.
P.S. Somebody seems to have made me a prophet. Shouldn't they have alternative classifications such as "nuissance" and "pain in the a$$"...
Does anyone know what if anything was wrong with Zarks projector?
This is the way I'm planning to go right now. I've allready got the Lens and the LOA lights, but I'm kinda lookin for a 5" LCD with better resolution.
I always thought the panel resolution was the only downfall to Zarks projector but the last few posts seem to point at somthing else.
This is the way I'm planning to go right now. I've allready got the Lens and the LOA lights, but I'm kinda lookin for a 5" LCD with better resolution.
I always thought the panel resolution was the only downfall to Zarks projector but the last few posts seem to point at somthing else.
OHP problem
Hi, I have a setupo with Sharp panel and OHP. I used it with the original Halogen bulb in the OHP and after it blew up I changed ii and installed a MH 400W bulb(realy big one). And the problem came. Before I had a beautiful image(a bit redish) and now I have totaly dim picture, unable to focus. I think that the problem is in the position of the bulb(refelctor is OK), because too much light pases to the ceiling(before it was only a little).
Thanks
BARBUCHA
PS: Sorry my english.
Hi, I have a setupo with Sharp panel and OHP. I used it with the original Halogen bulb in the OHP and after it blew up I changed ii and installed a MH 400W bulb(realy big one). And the problem came. Before I had a beautiful image(a bit redish) and now I have totaly dim picture, unable to focus. I think that the problem is in the position of the bulb(refelctor is OK), because too much light pases to the ceiling(before it was only a little).
Thanks
BARBUCHA
PS: Sorry my english.
Barbucha,
Lots of light hitting the ceiling indicates that your light source is definitely configured wrong.
1) What type of halogen did you have: was it an open bulb, or did it have a reflector?
2) If it was an open bulb, and the OHP has a built-in reflector, are you physically able to place the centre of the light bubble of the bulb at the point where the halogen filament used to go?
In the ideal OHP configuration, the light source is a single point of light, at he focal point of the lower of two fresnels. The light from the point source is collected by the first fresnel, and shaped by the second fresnel into a single conical beam of light extending upwards from the fresnel, to the OHP objective lens at the top.
If the bulb is in the wrong position such that the point source is not in the centre of the fresnel, then the light cone will also be offset - causing the apex of the cone to miss the objective lens, and be beamed all over your ceiling.
If the bulb is too close, or too far away from the fresnel, then the light cone will be too tall, or too short, or may not ever reach a point... Again, your ceiling gets the benefit.
Finally, if the light source is in the right place with respect to the fresnel, but has a badly adjusted reflector arrangement, or has too large a light emitting area, then you risk producing multiple overlapping light cones - each with its apex at a slightly differenrt position. (There may be only one light cone, but its apex may be smeared vertically, with no one position that is "the right one".)
In this case, you will get an image with poor definition and contrast, because the objective can only focus an image from the apex of a single light cone - the other light cones will overlay the focussed image with multiple unfocussed ones...
You may have one or more of these effects interfering with your projection.
That said, OHPs are a very clever design, and are much more forgiving than my description would indicate. (e.g. the small aperture of the objective with respect to the LCD image, and its distance from it, allows the objective to ignore all light that is not part of a light cone with its apex roughly at the right position. Only if the apex of a light cone is close to the objective position, does most of the light cone's energy flow through it: too high, or too low, and the light flows past it... The reflector arrangement means that instead of hitting the screen and reducing contrast, all light that does not go through the objective hits the ceiling instead... It is all quite clever!!!)
Thus, your task is to ensure that the light source you use, is correctly positioned and suitably reflected such that all its energy is projected as a single cone of light that hits the objective in its centre. In truth, nothing is perfect, and you can only do your best - if you can position the bulb such that you are satisfied with the image, then your job is done.
Bill.
Lots of light hitting the ceiling indicates that your light source is definitely configured wrong.
1) What type of halogen did you have: was it an open bulb, or did it have a reflector?
2) If it was an open bulb, and the OHP has a built-in reflector, are you physically able to place the centre of the light bubble of the bulb at the point where the halogen filament used to go?
In the ideal OHP configuration, the light source is a single point of light, at he focal point of the lower of two fresnels. The light from the point source is collected by the first fresnel, and shaped by the second fresnel into a single conical beam of light extending upwards from the fresnel, to the OHP objective lens at the top.
If the bulb is in the wrong position such that the point source is not in the centre of the fresnel, then the light cone will also be offset - causing the apex of the cone to miss the objective lens, and be beamed all over your ceiling.
If the bulb is too close, or too far away from the fresnel, then the light cone will be too tall, or too short, or may not ever reach a point... Again, your ceiling gets the benefit.
Finally, if the light source is in the right place with respect to the fresnel, but has a badly adjusted reflector arrangement, or has too large a light emitting area, then you risk producing multiple overlapping light cones - each with its apex at a slightly differenrt position. (There may be only one light cone, but its apex may be smeared vertically, with no one position that is "the right one".)
In this case, you will get an image with poor definition and contrast, because the objective can only focus an image from the apex of a single light cone - the other light cones will overlay the focussed image with multiple unfocussed ones...
You may have one or more of these effects interfering with your projection.
That said, OHPs are a very clever design, and are much more forgiving than my description would indicate. (e.g. the small aperture of the objective with respect to the LCD image, and its distance from it, allows the objective to ignore all light that is not part of a light cone with its apex roughly at the right position. Only if the apex of a light cone is close to the objective position, does most of the light cone's energy flow through it: too high, or too low, and the light flows past it... The reflector arrangement means that instead of hitting the screen and reducing contrast, all light that does not go through the objective hits the ceiling instead... It is all quite clever!!!)
Thus, your task is to ensure that the light source you use, is correctly positioned and suitably reflected such that all its energy is projected as a single cone of light that hits the objective in its centre. In truth, nothing is perfect, and you can only do your best - if you can position the bulb such that you are satisfied with the image, then your job is done.
Bill.
lamp
Hi guys,
this already wrote several time before, but I would like to write it again, it's about the specification of projector lamp we should use (correct me if I'm wrong):
Color Rendering Index:
The color rendering index (CRI) scaled 1 to 100. CRI is important in a home because it affects how furniture, decorations, and even people look. Incandescents are considered the best at 95 to 100. Newer Tri-Phosphor Fluorescent and Metal halide is rated above 80, while mercury vapor and old fluorescent are 62 or above. Using CRI with 84 or better gives very little color shift loss.
Light temperature:
If we translate white light to temperature, it's around 6000 degrees Kelvin (sun daylight as an example), below that temperature become redish, above become blueish.
We need white light like sun daylight for perfect projector.
Light intensity:
It measured with lumens, it's still in hot discussion, at the begining 10000 lumens seemed adequate, but recently 20000 lumens still not enough to produce bright projected image!
Arc gap:
short arc gap (shorter than 6mm), so the ideal point source light can be achieved, but now we discuss about more than one light source!
Qoute from this link maybe relevant with current discussion:
Because of the light emitting from the halide has bad uniformity, adds the light is symmetry to the axle of the light reflected from the face of the reflector, it requires a collection system or so called Integrator to uniform the distribution of light, and convert the circular illumination area into a rectangular area as the LCD panel (4:3 or 16:9) as seen in fig.3. The integrator has been used more often now called lens arrays, the first set of lens arrays divide the light reflected from the reflection into several elements. (Rectangular 4:3 or 16:9 distribution), and the arc will focus on the second set of lens arrays, and the second set of lens will add up the position of the first set of lens arrays on the LCD panel to achieve the uniformity. Using the rod glass is another method, using the effect of Kaleidoscope to create array point source, and uniformity achieved.
Anybody can explain this with more simple words?
And this:
There is another special reflector called orthogonal parabolic reflector. It is able to focus the light from long arc lamp into a single point.
What is orthogonal parabolic reflector look-like? and how's to make it?
see you.
Hi guys,
this already wrote several time before, but I would like to write it again, it's about the specification of projector lamp we should use (correct me if I'm wrong):
Color Rendering Index:
The color rendering index (CRI) scaled 1 to 100. CRI is important in a home because it affects how furniture, decorations, and even people look. Incandescents are considered the best at 95 to 100. Newer Tri-Phosphor Fluorescent and Metal halide is rated above 80, while mercury vapor and old fluorescent are 62 or above. Using CRI with 84 or better gives very little color shift loss.
Light temperature:
If we translate white light to temperature, it's around 6000 degrees Kelvin (sun daylight as an example), below that temperature become redish, above become blueish.
We need white light like sun daylight for perfect projector.
Light intensity:
It measured with lumens, it's still in hot discussion, at the begining 10000 lumens seemed adequate, but recently 20000 lumens still not enough to produce bright projected image!
Arc gap:
short arc gap (shorter than 6mm), so the ideal point source light can be achieved, but now we discuss about more than one light source!
Qoute from this link maybe relevant with current discussion:
Because of the light emitting from the halide has bad uniformity, adds the light is symmetry to the axle of the light reflected from the face of the reflector, it requires a collection system or so called Integrator to uniform the distribution of light, and convert the circular illumination area into a rectangular area as the LCD panel (4:3 or 16:9) as seen in fig.3. The integrator has been used more often now called lens arrays, the first set of lens arrays divide the light reflected from the reflection into several elements. (Rectangular 4:3 or 16:9 distribution), and the arc will focus on the second set of lens arrays, and the second set of lens will add up the position of the first set of lens arrays on the LCD panel to achieve the uniformity. Using the rod glass is another method, using the effect of Kaleidoscope to create array point source, and uniformity achieved.
Anybody can explain this with more simple words?
And this:
There is another special reflector called orthogonal parabolic reflector. It is able to focus the light from long arc lamp into a single point.
What is orthogonal parabolic reflector look-like? and how's to make it?
see you.
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