response time in LCDs

Some LCDs have 120hz, is this the same as 8ms? I would think so, but
I've seen some sets advertised as 120hz and others mentioned as 8ms
but not advertised as 120hz even though they apparently are.

Just trying to get it straight.

I would think this would really help the motion blur thing a lot.

The new Sharp *64u has 4ms, I would think they would really want to
advertise that but they dont' seem to.

Sony, for some reason doesn't really mention response time on its
40v3000 but it does mention it (120) on the xb4 which is more
expensive.

Odd that Sony, which I would think would be one of the leaders,
wouldn't be at the forefront of the low response times.

Or maybe there's more to it than response times?

Maybe my eyes are quick, but I thought I could see some pixelation in
some of these sets.

In article kpb writes:
Some LCDs have 120hz, is this the same as 8ms?

No.

I would think so, but
I've seen some sets advertised as 120hz and others mentioned as 8ms
but not advertised as 120hz even though they apparently are.

Just trying to get it straight.

I would think this would really help the motion blur thing a lot.

But, simply having a faster response, or more frequent updates alone won't
do it.


The new Sharp *64u has 4ms, I would think they would really want to
advertise that but they dont' seem to.

Because it is not as important as you think.


Or maybe there's more to it than response times?

Bingo.


Maybe my eyes are quick, but I thought I could see some pixelation in
some of these sets.

You probably don't. You probably see macroblocking.


Alan

On Sun, 30 Dec 2007 18:37:23 -0800 (PST) kpb wrote:

| Some LCDs have 120hz, is this the same as 8ms? I would think so, but
| I've seen some sets advertised as 120hz and others mentioned as 8ms
| but not advertised as 120hz even though they apparently are.

The response time is not a function of refresh/frame rate. Response is
how fast the pixel will change, given the directive to make the change.
Refresh rate is how often it could be given that directive to change.

There is a correlating impact between these two values. But they have
entirely different effects. Long response times makes moving things
blur (form a tail) across the screen. Slow refresh rates make moving
things jump across the screen. Combine poor performance on both of
these and moving things will form a pattern of several images in a row
on the screen.


| Just trying to get it straight.
|
| I would think this would really help the motion blur thing a lot.
|
| The new Sharp *64u has 4ms, I would think they would really want to
| advertise that but they dont' seem to.

I've found that response time and viewing angles tend to be a tradeoff.
I don't know if this is a technology thing or just a manufacturer cost
tradeoff decision.


| Sony, for some reason doesn't really mention response time on its
| 40v3000 but it does mention it (120) on the xb4 which is more
| expensive.

Below about 4ms, people tend to not notice anything better. As more and
more displays get to this level at reasonabl prices, I think you will
see less and less promotion of this feature.


| Odd that Sony, which I would think would be one of the leaders,
| wouldn't be at the forefront of the low response times.
|
| Or maybe there's more to it than response times?

Or maybe that response times aren't really a competitive advantage.


| Maybe my eyes are quick, but I thought I could see some pixelation in
| some of these sets.

Pixelation is another issue with many potential causes varying from poor
signals to insufficient CPU power to overcompression of the content.

--
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| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
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