taylor@sdcsvax.UUCP (Dave Taylor) (08/17/83)
(This is to answer a question that has been in my head for a while) Has anyone done or seen any research on what color CRT screen is better for prolonged periods? I suspect that it is a 'white' CRT with inverse video (ie black lettering on a white background) since it most closely resembles printed text, which we have been exposed to since Day One. (See the advertisement in the August "Computer Design" by Ball Corp. to see how nice black type on white can look...) Perhaps we can arrive on a consensus... stuck with green, --- Dave Taylor UCSD Computer Science Dept.
ralph@utcsrgv.UUCP (ralph hill) (08/18/83)
Ah yes, the screen colour question.
I have an 18 entry bibliography listing papers addressing such issues.
Unfortunately, I think almost all make assumptions about room light.
Anyway, the most dramatic conclusion I have found was a recommendation
that the monitors used be at least 1k lines tall, 100 hz non-interlaced,
back characters on white, and quite bright! Anyone ever seen a monitor
like that?? They wanted it to be back on white, and bright, so that it
could be used in a conventionally (over-)lit office. Once you do this,
you need the 100 hz non-interlace to ensure lack of flicker (sensitivity
to flicker increases with brightness).
Another reason for the brightness, is to cause the pupils to constrict,
improving focus. Apparently, about 80% of the people in (European) offices
have improperly corrected vision!
Personally, I use (at home) white on black, in a dimly lit room.
The bezel is black, and very closely approximates the reflectance of the
screen. This is quite nice in that there is no harsh constrast in the
primary visual field. Since I rarely use paper, this works out fine.
If I used paper a lot, I would probably have to turn the lights up
(they're on dimmers like they should be) and go to black on white
(but that means new fonts, better monitor, .... i.e., $$$).
The two key references are (in my own bibliography format):
German Standards Safety Regulations for Display Work Places in
1980 the Office Sector. Hamburg, West Germany:
West German Industrial Injuries Insurance In-
stitues.
Keywords: health and safety, work station
layout
The German health and safety regulations.
Extremely detailed. Extremely informative
(if you dig through it). Everything you ever
wanted to know about how to lay out a work
station properly.
In Germany, these regulations carry some le-
gal weight. If an employee can show that
they were injured on the job, and the em-
ployer does not follow the guidelines in this
report, the employer may be liable. I know
of no North American firm which makes VDTs
come close to meeting these guidelines.
Grandjean, E. Ergonomic Aspects of Visual Display
Vigliani, E. Terminals. London: Taylor and Francis.
(Eds.)
1980
If anyone knows of a cheap 1k+ line monitor that goes at 100hz
non-interlaced let me know. :-)
-------------------
Ralph Hill CSRG University of Toronto
ARPANet utcsrgv!ralph@UW-BEAVER
UUCP cornell ihnp4 ubc-vision linus floyd allegra uw-beaver >!utcsrgv!ralph
-or- decvax research duke cwruecmp >!utzoo!utcsrgv!ralphkramer@utcsrgv.UUCP (Bryan M. Kramer) (08/18/83)
Displays of black on white have always caused me trouble because of the intensity of the background. However, a few years ago I saw a number of articles describing research in LCD television. Has this gotten anywhere? It strikes me as an ideal solution: black on white using reflected light.
tugs@utcsrgv.UUCP (Stephen Hull) (08/18/83)
WRT the question of qhether to go with a very bright display in a bright
office, thus being able to see pen and paper, or to get a darker display
in a dimly lit office and be stuck with only using the CRT:
Perhaps the best solution is a dimly-lit CRT which has a built-in Luxo desk
lamp...
But seriously, folks, I worked on a PERQ with the supposedly 'normal' black
on white display, and heartily do NOT recommend its use. It looks nice, sure,
but after a couple of hours both I and everyone else who used it complained
of eye strain or headaches or fatigue. The problem seems to be twofold:
first, the black on white seems (I'm not trying to support this scientifically,
this is just a subjective opinion) to emphasize lack of sharpness of the
characters -- the text always seemed fuzzy, yet I'm sure it was no worse than
a standard white on black terminal. Second, when 95% of the screen is lit,
whatever minimal, only-detectable-by-peripheral-vision flicker is present
really gets to you after a while.
Something which had some impact -- possibly real and possibly psychological --
was the radiation business. By ballpark figures, a black on white screen
puts out 20 times the EM radiation a white on black does.
As for the "naturalness" of black on white, while this is a conventional
colouring system for the printed word, and thus may have some advantage
from a familiarity point of view, it's certainly not anything we have a
physiological preference for. Have any studies been done to compare
resolvability (not resolution) of B on W versus W on B?
And finally, black on white CRTs are NOT the same as hardcopy for the simple
reason that paper doesn't give off light. Mind you, it REFLECTS light...
hmmm, that could be equivalent, couldn't it? Or could it? Ah, well, just
another question to be answered from the Wonderful World of Ergonomics...
steve hull
--
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cornell, watmath, uw-beaver, ubc-vision }!utcsrgv!tugs
{ decvax, cwruecmp, duke, research }!utzoo!utcsrgv!tugs
Arpa utcsrgv!tugs@UW-BEAVERdave@utcsrgv.UUCP (Dave Sherman) (08/18/83)
I use a VT-100 in black-on-white-background mode, and a Concept AVT in
black-on-bright-orange-background. They seem the best for a lot of text
work. We're presently testing CAI on law students who have never worked
on terminals before, and this mode seems to be generally preferred.
Interestingly, a student told me yesterday that the hard part for her
was getting used to reading text vertically (i.e., on a screen which
holds the page in mid-air, which she looks across at). She found it
a big shift from looking *down* at printed text on her desk.
Dave Sherman
The Law Society of Upper Canada (utcsrgv!lsuc!dave)
--
{allegra,cornell,floyd,ihnp4,linus,utzoo,uw-beaver,watmath}!utcsrgv!davefaunt@hplabsc.UUCP (Doug Faunt) (08/19/83)
I'm not sure you're right about black letters on a white screen for two reasons: Black print on white background in print is not the optimum, just cheapest. The CRT is emitting light, and the printed page is reflecting light. (I also don't know that you're not right, but I think your reasons are invalid).
kurt@pyuxhh.UUCP (08/19/83)
I agree that a black on white display has a problem with being too bright. I find that glare is the biggest problem, also I think that the over use of florescent lighting (which blinks) leads to alot of problems. I would like an amber on black display with a dim florescent in the ceiling, and a swing arm incandecent (sp) desk lamp. Also I WOULD NOT banish windows as the lack of natural light has gotten us all in trouble.
kurt@pyuxhh.UUCP (08/19/83)
A more important question is whine. When we did a terminal search about six months ago, we discovered that about 90% of the terminals we looked at produced a high pitch whine that about 10% of our people found very disturbing. Strangly enough salesmen and supervisors could not hear this sound. I understand it comes from the flyback transformer, and is a function of the scan rate. We finaly selected TAB terminals as they did not seem to do this (very high scan rate).
mason@utcsrgv.UUCP (Dave Mason) (08/20/83)
The whine is from the windings in the flyback transformer. TVs do it too,
but the sound normally drowns it out. Most current terminals use TV technology
which uses a 15750Hz horizontal scan rate giving 262 (or 525 if interlaced)
raster lines. I hear it but have learned to mask it out long ago. (It can
be quite useful in a open plan office if you are the last to leave, you can
hear if everyone's terminal is switched off. Unfortunately this frequency is
a little high for the ears to figure ot the direction.)
The supervisors (and possible the salepeople) probably were older than the
average in the office and ears start rolling off high frequencies as you get
older. We're also not used to hearing such frequencies except as harmonics
so some people may have trouble (I do sometimes) detecting this strange
sensation as sound. The decibel level is not high (I don't) think, but I
sometimes wonder the contribution this may make to fatigue.
-- Gandalf's flunky Hobbit -- Dave Mason, U. Toronto CSRG,
{cornell,watmath,ihnp4,floyd,allegra,utzoo,uw-beaver}!utcsrgv!mason
or {cwruecmp,duke,linus,lsuc,research}!utzoo!utcsrgv!mason (UUCP)laura@utcsstat.UUCP (Laura Creighton) (08/20/83)
Hello gang, remember my earlier gripe about how some people do human factors engineering? Here is an example of why I have this gripe. Somebody wanted opinions on screen colours. He got a lot of opinions. But some of the people posting the opinions had a decidedly "I know that this is the best screen for all mankind and here is why" tone. This is what I find distressing. All of the people with contrary opinions are about to get screwed if the person with "the perfect terminal" ever gets it made the industry standard. Look at the vt100 if you want to see an industry standard that upsets many people (including me) when I have to use one. Yet some people find them the best in the world. laura creighton utzoo!utcsstat!laura
mcg@shark.UUCP (Steven McGeady) (08/22/83)
I find that the only time I have trouble reading my slow, green-posphour screen is when reading net.cog-eng. Can anyone explain this? mcg
rcj@burl.UUCP (08/25/83)
I have always both heard and read that green is easier on the eyes; I wish that I DID have green. Instead, I use my vt102 in inverse video mode (black letters on white background). Most people I work with think that I am crazy for doing so....they can't stand it. -- The MAD Programmer -- 919-228-3814 (Cornet 291) alias: Curtis Jackson ...![ floyd sb1 mhuxv ]!burl!rcj
john@genrad.UUCP (John Nelson) (08/26/83)
I consistantly use a vt100 in inverse video (black on white) with a sheet of circularly polarized green plastic of some kind in front of the screen (it TOTALLY eliminates glare). We have a version of "ls" that displays directories as BOLD, and executables as INVERSE video. It really works great! John P. Nelson (decvax!genrad!john)
silver@csu-cs.UUCP (09/01/83)
To digress on the subject: Imagine a version of ls(1) which uses different color lettering (on a color display) to highlight different file types. Actually, I don't have to imagine it, I've seen it done here at HP and it's startling, to say the least! Don't know if I could get used to it, though... It's distracting because it's almost TOO much information at once. Alan Silverstein, Hewlett-Packard Fort Collins Systems Division, Colorado ucbvax!hplabs!hpfcla!ajs, 303-226-3800 x3053, N 40 31'31" W 105 00'43"
derek@sask.UUCP (Derek Andrew) (09/02/83)
I recently attended a seminar here in Canada given by a consultant from France. He had said that European contries had indeed legislated the colours of the screen and background for the labour unions. He then rattled off which countries had chosen what colours. I did not get a chance to write them down (maybe one of our European sites could post a list) but the interesting thing is that no two countries had chosen the same colours. Derek Andrew, U of Saskatchewan, utah-cs!sask!derek