Dye doping will not work. The very sharp bandpass notches that are needed can only be produced by thin film dichroics, pigment molecules are far too random.
Pinkmouse,
If the bandpass regions were relaxed significantly for a DIY project so they were not so steep could dichroic dyes work to some success in a clear based carrier.
Everybody,
This whole black screen ChromaVue Sony screen thing is causing a great pradigm shift in my thinking and I am beginning to visualize what I think would be the perfect projection screen and how it would be build if such a thing could be manufactured. It would be fundamentally different than anything I have ever seen. First, it would have a dead black backing that did a good job of absorbing all light. Then it would be covered with a fine thin coating of tiny highly reflective glass mirror beads. These are tiny beads that are spherical in shape and have a mirror surface coated on them. The beads are small enough so that they are three or four times smaller than an on screen pixel.
Next the reflective beads are coated with the proper dialectric materials to created the narrow bandpass filters which transmit only the narrow spectrum three colors into the mirrored beads.
The beads transmit only the narrow bands which reflect back in all directions due to the mirror coating. Because of the spherical shape of the bead the light is reflected back in a wide angle thereby creating a virtual diffusive effect for the viewers.
The black backing of the screen is kind of like a shadow mask on a CRT television which increases black levels.
Such a screen would have high gain, high contrast, and little or no hotspotting and a wide viewing angle. The perfect screen.
If these little reflective glass beads with dichroic filters on them could be manufactured then anyone could make a very high end screen with only some black paint and some clear adhesive and some careful application.
Hezz
If the bandpass regions were relaxed significantly for a DIY project so they were not so steep could dichroic dyes work to some success in a clear based carrier.
Everybody,
This whole black screen ChromaVue Sony screen thing is causing a great pradigm shift in my thinking and I am beginning to visualize what I think would be the perfect projection screen and how it would be build if such a thing could be manufactured. It would be fundamentally different than anything I have ever seen. First, it would have a dead black backing that did a good job of absorbing all light. Then it would be covered with a fine thin coating of tiny highly reflective glass mirror beads. These are tiny beads that are spherical in shape and have a mirror surface coated on them. The beads are small enough so that they are three or four times smaller than an on screen pixel.
Next the reflective beads are coated with the proper dialectric materials to created the narrow bandpass filters which transmit only the narrow spectrum three colors into the mirrored beads.
The beads transmit only the narrow bands which reflect back in all directions due to the mirror coating. Because of the spherical shape of the bead the light is reflected back in a wide angle thereby creating a virtual diffusive effect for the viewers.
The black backing of the screen is kind of like a shadow mask on a CRT television which increases black levels.
Such a screen would have high gain, high contrast, and little or no hotspotting and a wide viewing angle. The perfect screen.
If these little reflective glass beads with dichroic filters on them could be manufactured then anyone could make a very high end screen with only some black paint and some clear adhesive and some careful application.
Hezz
Guys,
I have gone through the patent and the patent does not cover any aspect of manufacturing of the filters except in the most superficial detail.
It seems to assume that currently existing technology can be used in four different ways to build the screen. It is more of an idea patent then a manufacturing process patent.
Also, I made some assumptions above. One was that the dialectric materials that are deposited on glass to make dichroic filters could also be deposited on a metal like aluminum. So that they could be deposited on a mirrored surface.
The patent also describes dichroic filters which are reflective in the bandpass areas and transparent in the other light wavelengths. If dichroics of this nature could be deposited on glass then you could make glass beads from highly absorbent black glass and then polish them and deposit the reflective dichroic filter layers on the beads.
In closing, I wonder if anyone has tried making a high contrast DIY screen out of flat black paint and the reflective glass beads used for mixing with paint for road signs.
You could bond a thin coating of the reflective glass beads over a painted flat black surface for a higher contrast screen. Granted this does not have the filtering effect of the ChromaVue but it might work well for a cheap DIY screen.
Hezz
I have gone through the patent and the patent does not cover any aspect of manufacturing of the filters except in the most superficial detail.
It seems to assume that currently existing technology can be used in four different ways to build the screen. It is more of an idea patent then a manufacturing process patent.
Also, I made some assumptions above. One was that the dialectric materials that are deposited on glass to make dichroic filters could also be deposited on a metal like aluminum. So that they could be deposited on a mirrored surface.
The patent also describes dichroic filters which are reflective in the bandpass areas and transparent in the other light wavelengths. If dichroics of this nature could be deposited on glass then you could make glass beads from highly absorbent black glass and then polish them and deposit the reflective dichroic filter layers on the beads.
In closing, I wonder if anyone has tried making a high contrast DIY screen out of flat black paint and the reflective glass beads used for mixing with paint for road signs.
You could bond a thin coating of the reflective glass beads over a painted flat black surface for a higher contrast screen. Granted this does not have the filtering effect of the ChromaVue but it might work well for a cheap DIY screen.
Hezz
Jinan Huaming Microbead (http://glassbead.en.alibaba.com/offerlist.html) looks to be a good source for such beads. They even have aluminum coated glass beads - I wonder if these could somehow be polished to a mirror-like surface?
Anyway, on the off chance that they may somehow have the capability of restricting the wavelengths to be reflected, I have sent them an inquiry. If he responds with, "what range of wavelengths are we talking about?", I'm going to be like "Uuuhhhh..."
edit: It seems to me like this approach is likely to result in serious hotspotting - especially in projected white or near-white colors.
Anyway, on the off chance that they may somehow have the capability of restricting the wavelengths to be reflected, I have sent them an inquiry. If he responds with, "what range of wavelengths are we talking about?", I'm going to be like "Uuuhhhh..."
edit: It seems to me like this approach is likely to result in serious hotspotting - especially in projected white or near-white colors.
Interesting
This page has a table showing
Now, I have no idea how the refractive index of water translates to air, but Jinan Huaming Microbead seems to have a certain degree of control over the refractive index of their beads, so maybe we're onto something, here...
If we could get three types of beads with three refractive indices - one each optimized for red, green and blue, and find a way to apply three uniform coats to a black background...?
This page has a table showing
It gives wavelengths from 400 to 700nm (violet to red) with a mean value of 550 for a yellowish-green.
Now, I have no idea how the refractive index of water translates to air, but Jinan Huaming Microbead seems to have a certain degree of control over the refractive index of their beads, so maybe we're onto something, here...
If we could get three types of beads with three refractive indices - one each optimized for red, green and blue, and find a way to apply three uniform coats to a black background...?
I think if the beads were true spheres the hotspotting would be reduced but I may be wrong. The best method would be if the glass beads were made out of a black highly light absorbent glass and reflective dichroic filter material deposited right on the glass spheres. The beads would reflect only the narrow bands and absorb the other light. If only the front of the beads could be covered with the filter material it would be even better. IF heat became an issue the backing material could be black anonized aluminum to dissipate the heat.
But here is my newest idea for a cheap DIY screen.
Start with a piece of canvas or plywood and prepare the surface to make it relatively smooth. Then apply two or three coats of flat black laytex or enamel. Laytex is generally more flat but is less durable. Then using some kind of clear spray adhesive or beads mixed with clear poly or something cover the panel of black paint with a thin but evenly coated layer of the reflective beads.
Now the final layer needs to be a fine open weave cloth of a white color that is kind of sheer but not very shiney. Usually materials of this type are made of synthetics like nylon or polyester and are more shiney than cottons or natural fibers.
Stretch the fabric tightly over the panel so as to create tiny open voids in the fabic as much as possible. Hopefully any hottspotting could be controlled with this outer fabric.
Hezz
But here is my newest idea for a cheap DIY screen.
Start with a piece of canvas or plywood and prepare the surface to make it relatively smooth. Then apply two or three coats of flat black laytex or enamel. Laytex is generally more flat but is less durable. Then using some kind of clear spray adhesive or beads mixed with clear poly or something cover the panel of black paint with a thin but evenly coated layer of the reflective beads.
Now the final layer needs to be a fine open weave cloth of a white color that is kind of sheer but not very shiney. Usually materials of this type are made of synthetics like nylon or polyester and are more shiney than cottons or natural fibers.
Stretch the fabric tightly over the panel so as to create tiny open voids in the fabic as much as possible. Hopefully any hottspotting could be controlled with this outer fabric.
Hezz
Wait! I know! Black velvet beads!!! 😀 Could be hard to coat, though! 😉Hezz said:
I don't even want to think about the amount of time it would take to turn each bead so that it was filter side out! 😀
Or start with MDO plywood - very smooth and beloved by sign painters for it's paper outer layers.
DonnyB,
If you can talk this company into making glass beads out of a black glass that is visable light absorbant and then have a reflective dichroic filter with narrow reflective bands at the three RGB frequencies coated onto the beads we would have the perfect glass beads for projector screens. They could be used by themselves for high gain screen and combined with other methods for screen with less hotspotting.
Hezz
If you can talk this company into making glass beads out of a black glass that is visable light absorbant and then have a reflective dichroic filter with narrow reflective bands at the three RGB frequencies coated onto the beads we would have the perfect glass beads for projector screens. They could be used by themselves for high gain screen and combined with other methods for screen with less hotspotting.
Hezz
I'll see what I can do.
Just so I don't come off as an idiot when talking to him, are the wavelengths in the table (on the link I posted) correct? If so, we're looking to reflect 450nm (blue), 525nm (green) and 575nm (red). Sound right?
Just so I don't come off as an idiot when talking to him, are the wavelengths in the table (on the link I posted) correct? If so, we're looking to reflect 450nm (blue), 525nm (green) and 575nm (red). Sound right?
DonnyB,
The patent uses these ranges for the passband. So for a reflective filter type these frequency ranges need to be reflective.
475-490 nm BLUE,
525-565 nm GREEN,
615-650 nm RED,
These are the ranges used in the patent. It is important that each passband cover a small range to account for projector variations in color.
Also,
The other option is to coat white glass beads or mirrored glass beads with a transmissive filter at the same passbands.
Hezz
The patent uses these ranges for the passband. So for a reflective filter type these frequency ranges need to be reflective.
475-490 nm BLUE,
525-565 nm GREEN,
615-650 nm RED,
These are the ranges used in the patent. It is important that each passband cover a small range to account for projector variations in color.
Also,
The other option is to coat white glass beads or mirrored glass beads with a transmissive filter at the same passbands.
Hezz
Here is another Idea that I had and I wonder if it would work.
It's a variation on the Prof's DIY high gain screen.
First a sturdy backing material. Then a mylar mirrored surface or something similar. Then a thin sheer black colored material stretched tightly over the mirrored surface. This followed by a thin acrylic final layer that is sand blasted to a frosty surface finish.
It seems that the black material would let light pass through it's open weaves at angles close to perpendicular and at angles which are not too steep but the farther any ambient light is away from the perpendicular angle the more the black mesh would absorb it. This black mesh would probably reduce the gain of the screen but would hopefully increase contrast somewhat by acting like a shadow mask and increase contrast in higher ambient light conditions.
Hezz
It's a variation on the Prof's DIY high gain screen.
First a sturdy backing material. Then a mylar mirrored surface or something similar. Then a thin sheer black colored material stretched tightly over the mirrored surface. This followed by a thin acrylic final layer that is sand blasted to a frosty surface finish.
It seems that the black material would let light pass through it's open weaves at angles close to perpendicular and at angles which are not too steep but the farther any ambient light is away from the perpendicular angle the more the black mesh would absorb it. This black mesh would probably reduce the gain of the screen but would hopefully increase contrast somewhat by acting like a shadow mask and increase contrast in higher ambient light conditions.
Hezz
you guys are really talking over my head but darn it you guys got me interested in this. so is there any further developments?
Donny,
I wonder if anyone has patented this idea of putting dichroic filters on microbeads. I think the right formulation would be the screen to end all screens.
In fact I think that it is such a good idea that someone might steal it.
The only issue is that manufacturing could be difficult and since I'm not a chemist I have no real idea how difficult it would be to coat glass microbead with the specific dilectric materials.
Dichroic beads in larger sizes are already made for hobbiests but these are too large and not highly accurate filters with discrete passbands.
Since the glass microbeads are already available I think the best approach would be to contact the optical companies that make dichroic filters for other purposes since they would likely already be the closest to having the knowledge and technology to do it.
Hezz
I wonder if anyone has patented this idea of putting dichroic filters on microbeads. I think the right formulation would be the screen to end all screens.
In fact I think that it is such a good idea that someone might steal it.
The only issue is that manufacturing could be difficult and since I'm not a chemist I have no real idea how difficult it would be to coat glass microbead with the specific dilectric materials.
Dichroic beads in larger sizes are already made for hobbiests but these are too large and not highly accurate filters with discrete passbands.
Since the glass microbeads are already available I think the best approach would be to contact the optical companies that make dichroic filters for other purposes since they would likely already be the closest to having the knowledge and technology to do it.
Hezz
I read about a fabrication technique which might be useful here. (Unfortunately I can't find the link):
Clear beads are mixed into a liquid adhesive substrate. The mixture is painted onto a surface. As the substrate dries, it recedes, exposing part of the surface of each bead. I think this was for a retroreflective application.
Clear beads are mixed into a liquid adhesive substrate. The mixture is painted onto a surface. As the substrate dries, it recedes, exposing part of the surface of each bead. I think this was for a retroreflective application.
Charlie,
Thanks for the info. One thing that I have not been able to determine is whether or not the glass beads that are available and are used for making reflective paint are made from clear glass or white glass.
In theory the perfect screen for most applications would be made from white glass microbeads and then dichroic filter dialectric material which is transmissive at the three passbands and absorbative at all other frequencies would be deposited on the glass microbeads.
The white glass is highly diffusive and gives the best viewing angle and true white colors. But because the filter layer would absorb all light except at the three narrow passbands most ambient light would not be reflected or diffused and the screen would appear dark gray or black even in a well lit room. Only the light at the passbands which would travel through the filter would hit the white glass microbead surface and be diffused\reflected back to the viewer.
Contrast could be improved even further by depositing a thin even layer of the microbeads over a black light aborbing surface. It would act like a shadow mask increasing appearant black levels because of the very small black spaces between the glass microbeads.
Hezz
Thanks for the info. One thing that I have not been able to determine is whether or not the glass beads that are available and are used for making reflective paint are made from clear glass or white glass.
In theory the perfect screen for most applications would be made from white glass microbeads and then dichroic filter dialectric material which is transmissive at the three passbands and absorbative at all other frequencies would be deposited on the glass microbeads.
The white glass is highly diffusive and gives the best viewing angle and true white colors. But because the filter layer would absorb all light except at the three narrow passbands most ambient light would not be reflected or diffused and the screen would appear dark gray or black even in a well lit room. Only the light at the passbands which would travel through the filter would hit the white glass microbead surface and be diffused\reflected back to the viewer.
Contrast could be improved even further by depositing a thin even layer of the microbeads over a black light aborbing surface. It would act like a shadow mask increasing appearant black levels because of the very small black spaces between the glass microbeads.
Hezz
DIY Black Screen
I ran across this past thread from jr hilton.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=22498&perpage=10&pagenumber=13
He describes how to make a black screen out of sandblasted lass and paint. I know this is not the method being described in this post, but it would be something a DIYer can do.
I ran across this past thread from jr hilton.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=22498&perpage=10&pagenumber=13
He describes how to make a black screen out of sandblasted lass and paint. I know this is not the method being described in this post, but it would be something a DIYer can do.
Thanks Booger,
I think that old idea JR Hilton describes is the last bit of information we need to make a really good high contrast DIY screen.
So here's my new recipe using JR's idea.
1. Glue mirrored mylar to backing plate.
2. Stretch sheer black or gray cloth across the mirrored surface and glue with clear adhesive.
3. Take a relatively thin sheet of acrylic and sand blast it very thoroughly with small and large size grains.
4. Clean the sheet and spray paint thined down black plastic paint on the surface.
5. Lightly sand or use a scotchbrite pad to remove the top surface of paint and reveal most of the frosty white surface finish but leaving the black paint down in the deeper pits and rough areas.
6. Glue the acylic sheet with clear adhesive to the first reflective sheet.
7. For a higher gain screen omit the sheer cloth between the plastic and mylar mirror.
The image in JR's post didn't save here so here is a copy:
Even though this screen technique was developed with rear projection in mind I think that it would work really well with a mirrored backing.
Hezz
I think that old idea JR Hilton describes is the last bit of information we need to make a really good high contrast DIY screen.
So here's my new recipe using JR's idea.
1. Glue mirrored mylar to backing plate.
2. Stretch sheer black or gray cloth across the mirrored surface and glue with clear adhesive.
3. Take a relatively thin sheet of acrylic and sand blast it very thoroughly with small and large size grains.
4. Clean the sheet and spray paint thined down black plastic paint on the surface.
5. Lightly sand or use a scotchbrite pad to remove the top surface of paint and reveal most of the frosty white surface finish but leaving the black paint down in the deeper pits and rough areas.
6. Glue the acylic sheet with clear adhesive to the first reflective sheet.
7. For a higher gain screen omit the sheer cloth between the plastic and mylar mirror.
The image in JR's post didn't save here so here is a copy:
Even though this screen technique was developed with rear projection in mind I think that it would work really well with a mirrored backing.
Hezz
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