CRTs technically fixed dot/pixel too?

I

imzjustplayin

[H]ard|Gawd
Joined
Jan 24, 2006
Messages
1,171
LCDs, plasmas etc, are all fixed pixel displays and suck at non native resolution material yet CRTs are suppose to be ok with this. Now I'm wondering, aren't CRTs technically fixed pixel/dot displays as well? I mean some do 480i and others do 1080i. So I'm wondering, why do people not consider CRTs as fixed pixel displays.
 
http://en.wikipedia.org/wiki/Cathode_ray_tube

that should pretty much answer all your questions.

but to sum it up, CRTs don't have a fixed pixel size but rather an aperture grille or similar structure that allows light of varying combinations of red green and blue to reach your eye. this structure represents a limitation in visual resolution, although theoretically any pixel resolution is possible provided the electronics and mechanical parts are suited to it.
 
They are fixed pixel masks/grilles but the phosphor glow generates pixels that are visually more round edged than an LCD so different resolutions dont suffer like an LCD.
This page has pictures of the aperture grille and shadow mask while in use, halfway down.
http://en.wikipedia.org/wiki/Cathode_ray_tube
You can see that neither of them have sharp edges to the pixels.

Also a CRTs output is analogue and is capable of rendering a much larger colour gamut.
LCDs divide the colour gamut into a set number of colours and the gamut is limited by the Flourescent tubes output and any filters on the LCD display.
Using a different resolution needs more than 1 pixel that are shaded to represent a single pixel on screen.
The wider colour gamut gives a less 'digital' look as the shades are more natural and not tied to particular values.


Not all LCDs suck at lower res, they have been getting much better.
It depends on the signal processing used, this seems to be advancing.
Also better filters on the LCD screen can help smooth the image.

I got my Sister an extremely cheap 22" 1680 res LCD for xmas and it looked fantastic at 1024, I was surprised.
 
Blahman said:
http://en.wikipedia.org/wiki/Cathode_ray_tube

that should pretty much answer all your questions.

but to sum it up, CRTs don't have a fixed pixel size but rather an aperture grille or similar structure that allows light of varying combinations of red green and blue to reach your eye. this structure represents a limitation in visual resolution, although theoretically any pixel resolution is possible provided the electronics and mechanical parts are suited to it.
Click to expand...
Well, that's basically my point, the resolution is limited by the apeture grille/shadow mask and that in a sense makes it a fixed pixel display.
 
no, because the holes in the grille are not pixels -- don't confuse the two -- and it would be virtually impossible to map a single pixel (more specifically RGB subpixel) to a single hole in the aperture grille. ever try getting zero overscan or underscan and perfect geometry on a CRT? not easy. now try doing the same thing on a microscopic scale for millions of tiny holes on your screen.

CRTs are an analog technology, meaning they don't have discrete units of resolution, i.e. pixels on an LCD panel, but as I said there is a finite but unmeasurable limit to their clarity which is determined more by the alignment of the electron beams, their interaction with gases in the vacuum tube and the phosphor coating, and the way the resultant R,G and B light filters through the aperture grille.
 
A CRT is a projector of sorts, with an electron gun that fires the image on to the back of a screen....that's the most simple explination. What limits the resolution of the image is the gun itself (the projector), not the screen.
 
The Electron Gun. That's what gives discriminating FPS players a little edge.
 
Blahman said:
no, because the holes in the grille are not pixels -- don't confuse the two -- and it would be virtually impossible to map a single pixel (more specifically RGB subpixel) to a single hole in the aperture grille. ever try getting zero overscan or underscan and perfect geometry on a CRT? not easy. now try doing the same thing on a microscopic scale for millions of tiny holes on your screen.

CRTs are an analog technology, meaning they don't have discrete units of resolution, i.e. pixels on an LCD panel, but as I said there is a finite but unmeasurable limit to their clarity which is determined more by the alignment of the electron beams, their interaction with gases in the vacuum tube and the phosphor coating, and the way the resultant R,G and B light filters through the aperture grille.
Click to expand...

I realize what a pixel is which is why I carefully choose my words saying pixel/dot. Anyways I have gotten zero over/under scan on a CRT, yes it wasn't easy but it was possible. Why was this possible? Because there is a shadowmask/apeture grille to align with...

Also I realize CRTs are an analog technology but because of the limitations of the shadow mask/apeture grille, there are limitations to its resolution which is why some monitors support a given resolution over others, because their dot pitch is significantly finer than the cheaper monitors.
 
Blahman said:
no, because the holes in the grille are not pixels -- don't confuse the two -- and it would be virtually impossible to map a single pixel (more specifically RGB subpixel) to a single hole in the aperture grille. ever try getting zero overscan or underscan and perfect geometry on a CRT? not easy. now try doing the same thing on a microscopic scale for millions of tiny holes on your screen.

CRTs are an analog technology, meaning they don't have discrete units of resolution, i.e. pixels on an LCD panel, but as I said there is a finite but unmeasurable limit to their clarity which is determined more by the alignment of the electron beams, their interaction with gases in the vacuum tube and the phosphor coating, and the way the resultant R,G and B light filters through the aperture grille.
Click to expand...

CRTs have resolution defined by the number of groups of RGB phosphor dots/lines.
Each group defines one pixel resolution of the display.
You can see the discretely lit phosphor dots/lines in the links given above in earlier posts.
The size of the dots is the dot pitch which defines how many will fit within the screen area.
This gives us the maximum resolution of the screen.

The analogue part of a CRT is the range of voltages applied to the electron gun.
This defines the brightness of each of the RGB phosphors on each pixel and is not bound to only the digital values sent from a PC.
The contrast, brightness and colour settings are analogue too as they are controlled with the power to the electron gun.
 
Nenu said:
CRTs have resolution defined by the number of groups of RGB phosphor dots/lines.
Each group defines one pixel resolution of the display.
You can see the discretely lit phosphor dots/lines in the links given above in earlier posts.
The size of the dots is the dot pitch which defines how many will fit within the screen area.
This gives us the maximum resolution of the screen.

The analogue part of a CRT is the range of voltages applied to the electron gun.
This defines the brightness of each of the RGB phosphors on each pixel and is not bound to only the digital values sent from a PC.
The contrast, brightness and colour settings are analogue too as they are controlled by the power to the electron gun.
Click to expand...
Exactly..
 
imzjustplayin said:
LCDs, plasmas etc, are all fixed pixel displays and suck at non native resolution material yet CRTs are suppose to be ok with this. Now I'm wondering, aren't CRTs technically fixed pixel/dot displays as well? I mean some do 480i and others do 1080i. So I'm wondering, why do people not consider CRTs as fixed pixel displays.
Click to expand...

Because a CRT is not a fixed dot/pixel display. Especially not technically.

If your real question is -- are CRTs limited in the resolutions they can clearly display, then absolutely they are by several factors. However, they are indeed far more flexible in that regard than LCDs...

Not a bad sacrifice to get an LCD's perfect geometry. (Though LCD's have other limitations as we know...)
 
In an LCD, each and every single sub-pixel is addressable and directly changeable and are NOT physically adjustable in any way, shape, or form.

In CRT they can't (at least not easily) be individually controlled. And by adjusting the voltage to the focus grid in the electron gun you can make the displayed pixels larger or smaller. Larger pixels = smaller resolution. There comes a point where the beam can only be focused so far before the either voltage is maxed and no more change can be had, or the beam starts to invert and thus gets larger. That's parts of where the resolution limts come into play, the other part is the timing limitations of the CRTs logic hardware. There aren't 1280x1024 or 1600x1200 holes in shadow masks or aperature grillles inside CRTs, There are literally millions of of holes. I've taken apart an old 14" 640x480 monitor and saw this for myself.
 
You must log in or register to reply here.
Back
Top