wrote in message
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Thank you Mr. Richard, Denny.
Please not be sick of my more questions.
From your opinion, you like "needle" meters. I want to know why most of
digital manufacturers made numeric readouts. I think they have
investigated markets, and then they done these kinds of products. Since
I browsed aircraftspure catalogues. I found numeric readout digital
meters stand in front of selling catalogue. I guessed there are a lot
of people buy and use them. Maybe I am wrong.

Luo

Not necessarily wrong--or right.

Numeric digital meters have been around for quite a while. When the concept
was new, a solid state analog display was prohibitively expensive--where it
was even available. So, if the requirement was only to obtain a steady
state reading and write it in a book or log, they worked just fine and
eliminated parallax and any disagreement between technicians interpolating
the numbers. In addition, many meters had a "peak hold" function which
could preserve peak values until they could be copied from the face of the
meter. Even 25 years ago, seven segment displays were cheap, bright, and
readable; and, with the available rubber cover, the package could be dropped
on a concrete floor without damage or loss of accuracy.

Besides, when we needed to tune anything, or watch anything dynamic, we
could still get the old analog meter from the shelf, supply room, or truck.
So, no one really ever converted to digital readouts--but they are really
rugged, light, and useful for some tasks.

At the moment, I can think of a few places in an aircraft cockpit where
digital flight instrument readouts are acceptable, and even useful, but none
where they have a clear advantage.