math with monitors...or something

[Bash]

This might be considered somewhat technical:
All along I've assumed that the dot pitch / aperture grill pitch was the spacing between pixels, but then I did some math...

Using the Iiyama Vision Master Pro 510 as an example (which is a very nice monitor, btw):
20 inch viewable
aperture grille pitch = .25mm
max res = 2048x1536

20 inch viewable means that you have a picture which is 16 inches across and 12 inches tall
(...pythagorian theorem 16^2 + 12^2 = 20^2)

.25mm grille pitch =
(.025cm)(1in/2.54cm) = .009843 inch pitch

The monitor is 16 inches across & has a pitch of .009843:

(16" / .009843") ~= 1625
(12" / .009843") ~= 1219

So my big assumption there was that the aperture grille pitch is equivalent to horizontal pixel spacing. If this is indeed the case, it would imply that this monitor can have a max res of 1625 x 1219. How do they manage 2048x1536??

I suppose this is just a really complicated way of asking what the aperture grille pitch really means...

-Bash

[This message has been edited by Bash (edited June 29, 2001).]

[Adisharr]

Originally posted by Bash:
This might be considered somewhat technical:
All along I've assumed that the dot pitch / aperture grill pitch was the spacing between pixels, but then I did some math...

Using the Iiyama Vision Master Pro 510 as an example (which is a very nice monitor, btw):
20 inch viewable
aperture grille pitch = .25mm
max res = 2048x1536

20 inch viewable means that you have a picture which is 16 inches across and 12 inches tall
(...pythagorian theorem 16^2 + 12^2 = 20^2)

.25mm grille pitch =
(.025cm)(1in/2.54cm) = .009843 inch pitch

The monitor is 16 inches across & has a pitch of .009843:

(16" / .009843") ~= 1625
(12" / .009843") ~= 1219

So my big assumption there was that the aperture grille pitch is equivalent to horizontal pixel spacing. If this is indeed the case, it would imply that this monitor can have a max res of 1625 x 1219. How do they manage 2048x1536??

I suppose this is just a really complicated way of asking what the aperture grille pitch really means...

-Bash

[This message has been edited by Bash (edited June 29, 2001).]

You can support a resolution without actually being able to resolve it. It just may not be able to display every single pixel. Try displaying 800x600 on a TV and while you will get a pic, the details will be lost.. Not quite the same thing but a similar analogy..



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- You can milk anything with nipples -

[Bash]

Originally posted by Adisharr:
You can support a resolution without actually being able to resolve it. It just may not be able to display every single pixel. Try displaying 800x600 on a TV and while you will get a pic, the details will be lost.. Not quite the same thing but a similar analogy..

that's true, but I'm sure that's not the case on a high quality monitor like the Iiyama I listed. If you do the math it works out the same for almost any monitor.

-Bash

[sww]

That number is diagonal. YOu probably have a .21 or better horizontal distance between pixels.

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Do they always play disco?
Yeah, it's hell.

[GoSharks]

In terms of a monitor there really is no concept of a pixel. Monochrome monitors did not have a mask structure. They used a single beam and no mask structure. The entire inside face of the CRT was coated in phosphor. From the monitors point of view the pixel was defined for the most part as the size of the electron beam. Same concept in a color monitor, only you have three beams and a mask to ensure the correct beam hits the correct color phosphor. For all the monitor cares, the video card could be building each line out of millions of active logical pixels. I like to think of a logical pixel as the speed thee video card modulate the beam, this determines beam size.

The number of the holes in the mask and stripes in the aperture grill technically set the maximum resolution of the monitor. At lower resolutions the logical pixels simply cover more than one hole or slot. The logical pixels do not need to line up with the physical holes or slots nor is there any mechanism to do so.

At resolutions that exceed the number of holes or slots across the screen, logical pixels (electron beam size) no longer hit the phosphors accurately enough to guarantee constant colors or luminance. Some of the beam is intercepted by the mask structure. On monitors with lower horizontal dot / aperture pitch, more of the beam is intercepted by the mask. However an image will still be displayed and in practice will look OK.

I find it is best to run at a minimum of 85Hz-refresh rate and resolutions just below the maximum number of holes or slots in the mask to keep accurate colors and luminance. This is easy to calculate.

For example: A 21" monitor typically has a horizontal viewable area of 395mm. Let's assume it has a 0.22mm horizontal dot pitch. 395 * 0.22 = 1795 dots across the screen. A monitor with the same viewable area and a 0.24mm horizontal dot / aperture pitch has 1645. This is one reason 1600 horizontal resolution is so popular.

Vertically is not so much a problem. A typical 21" monitor has a vertical viewable area of 295mm. Aperture grill monitors have a 0.00mm vertical aperture pitch. Vertical resolution capability is virtually unlimited. As with every technology the trade off is more beam current hitting the phosphor making them more susceptible to screen burn. Use a screen saver!

Most shadow mask monitors have a 0.14mm vertical dot pitch. 295 / 0.14 = 2107 lines far more than any video card can produce at any decent refresh rate.

Good question. I hope this helps

Jim Witkowski
Chief Hardware Engineer
Cornerstone / Monitorsdirect.com


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Jim at http://www.monitorsdirect.com