Hi all,

        Recently, a friend of mine asked me exactly how a PC monitor matches up
logical pixels to physical pixels in the raster on the screen. Of course, I
know that the electron beams from the R,G,and B guns are scanned
horizontally and vertically. However, it would seem to me that the monitor
would have to ensure that the start of the signals on each scan line
actually began on a real pixel,otherwise various odd patterns (akin to
aliasing) would occur if the data was out of sync by even a fraction of a
physical pixel. Viewing a monitor using a magnifier,we were also able to
see that as we turned the "horizontal position" knob, the horizontal
position actually seemed to only take on certain discrete positions,such
that pixels in the image always lined up exactly with physical pixels in
the raster.
        While I understand how horizontal and vertical sync signals can ensure
that each scan line and frame begin at the right time in the signal stream
coming from the video card, I don't understand how the monitor electronics
ensures that it lines up with physical pixels. This would seem to be a
great engineering problem,because a slight drift or jitter in the
positioning could have grave effects on the image.

Can someone please explain this to me?

Thanks,

Sean

|
| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
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