200106291102_mc3-d7ac-3...@compuserve.com, Cortland Richmond
72146@compuserve.com inimitably wrote:
the FCC H
pattern is designed to generate a periodic
signal as the electron beam is swept across
the screen and turned on and off.
Indeed, but it is an unrealistically severe operating
.
Cortland
== Original Message Follows
Date: 29-Jun-01 07:02:02 MsgID: 1078-56979 ToID: 72146,373
From: David Heald INTERNET:davehe...@mediaone.net
Subj: Re: LCD Monitors etc.
Chrg: $0.00 Imp: Norm Sens: StdReceipt: NoParts: 1
=There really ARE Class B computers, but you
have to work to make them, and you have to look
to FIND them. I've worked on some of them.
Between CRT's and LCD's, the generators are
different, but the levels are not necessarily
lower for an LCD.
A CRT has a fairly powerful, high frequency
Passive LCD monitors can be quiet. However, most new monitors I have seen
use active matrix Thin Film Transistor (TFT) technologoy which provides a
better picture but are considerably worse for emissions. If you compare the
two technologies you will see the reason. This has been consistent
To: george.stu...@watchguard.com; emc-p...@majordomo.ieee.org
Subject: Re: LCD Monitors etc.
George,
I did a number of experiments on 15 monitors for a machine HMI. They are
indeed quiet, but there is quite a difference between manufacturers.
Most of the problems I had to fix were
Greetings all,
At a former job, I actually performed many scans of LCD monitors from
many 'unnamed' manufacturers and found them to be different from
normal CRT's for emissions purposes. The LCD's would incorporate fast
(for monitors) clocks for processing. I have seen clocks anywhere from
65
George,
I did a number of experiments on 15 monitors for a machine HMI. They are
indeed quiet, but there is quite a difference between manufacturers.
Most of the problems I had to fix were related to leakage through the display
from circuitry behind it.
Derek.
George,
The LCD itself does not usually use high voltages, but most are
supplied with a fluorescent tube backlight. This is usually driven by a
high-frequency (50+ kHz) oscillator with an output designed to deliver
an open circuit voltage in the low kilovolt range to strike the
tube, followed by
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