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and if they are, to what extent?
Are phosphor sheets used in CRTs transparent?
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In summary, the conversation discusses the transparency of phosphor particles in CRT TVs and their potential usage in creating a transparent coating. Further discussion includes the use of an electron beam to excite phosphor and the potential issues with X-ray generation. Alternative technologies such as electroluminescence are also mentioned as a possible solution. It is noted that while phosphors in plastic film may not be transparent, there are other materials such as glasses and single crystals that can provide transparency.
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berkeman
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chhitiz said:
I don't think they are, but it would take some digging to figure this out. What is the context of the question?
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well, if you look at a CRT TV turned off, you just see blackness (and a bit of reflection of the screen), not tiny red green blue dots, so i think, maybe they are transparent.
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berkeman
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chhitiz said:
Look closer with a magifying glass...
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berkeman
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berkeman said:
And use a flashlight. You should be able to see the phosphur surface, not the inside of the CRT.
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how very stupid of me. another thing, can you tell me if the indivudual particles of phosphor are at micro or nano scale? if they they are nano sized and embedded (closely packed) in a plastic sheet, would it be transparent.
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berkeman
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chhitiz said:
It sounds like you would like to have a way to have a transparent coating that has the properties of phosphor? Are you going to use an electron beam to excite the phosphor? Are you aware of the X-ray generation issues with using an electron beam to excite phosphor?
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Baluncore
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The CRT EHT voltage was used to accelerate an electron beam that could then be focussed and deflected to raster scan the phosphor screen. There is no need for EHT to cause a phosphor to emit visible light. The generation of X-rays of 10 to 30keV is best avoided.
Visible light has an Energy = Plank's constant x Frequency. Three volts is sufficient as is demonstrated by the forward voltage of light emitting diodes.
Maybe consider electroluminescent display technology where a phosphor is placed between the plates of a capacitor. http://en.wikipedia.org/wiki/Electroluminescence
Visible light has an Energy = Plank's constant x Frequency. Three volts is sufficient as is demonstrated by the forward voltage of light emitting diodes.
Maybe consider electroluminescent display technology where a phosphor is placed between the plates of a capacitor. http://en.wikipedia.org/wiki/Electroluminescence
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These phosphors can not be transparent even if embedded in a plastic film due to the difference between the refractive indexes of the polymer and the inorganic phosphor particles. However, if you need a transparent luminescent material there are glasses and single crystals for this purpose.
1. What are phosphor sheets used for in CRTs?
Phosphor sheets are thin layers of material that are used to coat the inside of a cathode ray tube (CRT). They emit light when struck by electrons, allowing for the creation of images on the screen.
2. Are phosphor sheets transparent?
No, phosphor sheets are not transparent. They are typically made of a phosphor powder mixed with a binder and applied as a coating, making them opaque.
3. How do phosphor sheets work in CRTs?
In CRTs, an electron gun shoots a beam of electrons towards the phosphor sheets on the screen. The electrons collide with the phosphors, causing them to emit light and create the images we see on the screen.
4. What materials are used to make phosphor sheets in CRTs?
The most common materials used to make phosphor sheets in CRTs are zinc sulfide and cadmium sulfide. These materials are mixed with a binder, such as silicone, to form a paste which is then applied to the inside of the CRT screen.
5. How do phosphor sheets affect the image quality on a CRT?
The quality of the phosphor sheets used in CRTs can greatly impact the image quality. The size and composition of the phosphor particles, as well as the thickness and uniformity of the coating, can affect factors such as brightness, contrast, and color accuracy.