[Linux-Anyway] Re: 19" CRT Monitor setup in SW9.1
- From: Horror Vacui <horrorvacui@xxxxxxx>
- To: Linux-Anyway@xxxxxxxxxxxxx
- Date: Fri, 5 Nov 2004 02:08:07 +0100
On Thu, 4 Nov 2004 22:37:32 +0100
Godwin wrote:
> On Thu, 04 Nov 2004 20:41:45 +0000, John Richard Smith
> <BAGSOFCHOICE@xxxxxxxxxxxxxxxxxxxxx> wrote:
>
> > I walk about other peoples office situations and often
> > wonder how the poor devils manage to work with it.
>
> Lack of choice?
Well, fluorescent lighting doesn't have to be bad. If installed properly
(as I guess it will be in most offices), there is no flicker because
lamps are connected to three different phases. The sinusoidae
(sinusoides???) are shifted by 120 degrees, so even though the amount of
light the fluorescent tube emits represents the amount of current
flowing through rather accurately (that is, gives almost no light as the
sinusoide passes through 0, and full blast while the sinusoide is at a
peak), the shift in the phase makes for a virtually constant amount of
light emitted. Adding up the voltage (while disregarding the polarity)
at any point on the x axis will give you a constant, so if there is a
flicker at all, it can only happen if the fluorescent tubes perform in a
non-linear fashion, or you're sitting too close to a lamp, or you're
staring at a lamp directly.
The amount of light emitted by an incandescent lamp directly depends on
the temperature of the glowing element, so even large variations in the
current have almost no effect - at 50 Hz it's too fast to let the
temperature vary for more than a fraction of a degree. Even a
considerably greater variation in temperature would be hardly
noticeable, since it would mean only a variation in light temperature.
Apropos light temperature: 6500� Kelvin (which is what normal lightbulbs
usually give) is the maximum a glowing element can take before it starts
emitting material. This is no different for a halogen lamp, yet it can
come quite close to 9300�K - "halogen" is a reference to the gas
filling, which instead of interacting with the radiated material keeps
it afloat and generates a material halo ("halo"-"gen") around the
glowing element. The material from the halo than falls back on the wire
thanks to the magnetic field. If this field were constant all over,
halogen bulbs would last for ever, but since it is not, over time the
wolfram wire becomes thicker on the ends and thinner in the middle,
until it breaks.
My favourites in artificial light:
1 Flashes (including xenon lamps in headlights - it's the same
principle)
2 Fluorescent
3 LED
4 Halogen
The horrors:
1 Natrium lamps - the yellowish-to-orange lamps often used in street
lighting. Distort every colour, flicker awfully.
2 Mercury lamps - the white fluorescent bulbs that glow purple when
turned on and need about ten minutes to develop to white (though still
kind of awfully purplish). Also awful flicker.
So, now call me Mr. Tangent.
>
> Personally I'd love to have a larger monitor with a higher refresh
> rate so that it would be easier on the eyes. As things are I have to
> make do with a 10 year-old 15" monitor that doesn't do anything more
> adventurous than 1024x768 at 60Hz.
Mine's a 19" capable of 1600x1200 at 72Hz, intolerably blurred, and
1280x1024 at 75Hz with a noticeable blur and insufficient contrast. I'm
hoping that the growing popularity of TFT's will make good CRT's
cheaper. In fact, we're gradually replacing CRT's with TFT's at work,
and I hope I can fool the boss into selling me a 21" flat CRT Iyyama.
(I'm mostly enthusiastic about new technology because it makes good
older technology more available - though I probably shouldn't hold my
breath waiting to come across a fool selling his old Leica because he's
got himself a X megapixel digital camera...)
>
> The monitor is, however, on its last legs. The blue channel cuts out
> from time to time, and the on/off switch is bust (have to pull the
> plug to turn the thing off). When it does finally go I'll *have* to
> buy something to replace it...
I wonder that you put up with this - I've seen quite good used 17"
monitors for less than 10 Eur, and I've picked up two good-ish 15"
Philips off a recycling dump here for free. You can surely find
something nice if you look for it, for 0-20 Eur.
Cheers
--
Horror Vacui
Registered Linux user #257714
Go get yourself... counted: http://counter.li.org/
- and keep following the GNU.
--
Horror Vacui
Registered Linux user #257714
Go get yourself... counted: http://counter.li.org/
- and keep following the GNU.
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