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From: rcpt@rw8.urc.tue.nl (Piet Tutelaers)
Newsgroups: comp.unix.bsd
Subject: An overview of 17 inch monitors (2nd edition)
Message-ID: <rcpt.729818471@rw8.urc.tue.nl>
Date: 15 Feb 93 23:21:11 GMT
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An overview of 17 inch X-monitors
---------------------------------
(February 1993)
Spending a lot of money in computer power with a 14 inch monitor seems
like buying a splendid stereo equipment and saving on speakers. In this
article I have tried to give an overview of the available 17" monitors
and the selection criteria that are important when you are planning to
buy such a bigger monitor. Especially if you want to work with X-windows,
the window standard for UNIX.
A 17 inch monitor with a viewing area of 314x250 mm (12.4x9.8 inch)
offers about 50 percent more visual space than a 14 inch monitor with a
typical viewing area of 260x197 mm (10.2x7.7 inch). If you want to do
CAD/CAM or DTP you perhaps need an even bigger monitor. For a good 17
inch monitor you will pay quite a lot of money but there are coming
affordable monitors which are already very usefull for windows.
1. What matters?
-----------------
Most 17 inch monitors offer the 1280x1024 ADDRESSABILITY. To support
this 1280x1024 mode with 256 colors you will need an expensive graphics
card providing at least 2MB of on-board video memory. This investment
might be worthwhile if you are planning to do detailed work with CAD/CAM
or DTP otherwise the 1024x768 and 1152x900 modes will be sufficient for
most of us. And you don't need to spend a lot of money in your graphic
controller because both resolutions will fit in 1MB video (V)RAM.
Another concern with 17 inch monitors is the READABILITY. For a reading
distance of 40 cm on paper the optimal fontsize is 9-11 points. The
optimal reading distance for a monitor is about 50 cm from the screen
corresponding to letter heights of 11-15 points. The resolution of the
fonts should match the resolution of the screen otherwise the fonts will
become too large or too small. Next table summarizes the screen
resolutions for the different popular MSDOS addressabilities. The 75dpi
fontset suits both SVGA (14") and XVGA (17").
addressability pixels per inch
14 inch 17 inch
640x 480 (VGA) 62 dpi 49 dpi
800x 600 (SVGA) 78 dpi 61 dpi
1024x 768 (XVGA) 100 dpi 78 dpi
1152x 900 117 dpi 92 dpi
1280x1024 133 dpi 104 dpi
Screen resolution depending on addressability and
monitor size. Visual screen size on a 14 inch
monitor is typical 260x197 mm (10.2x7.7 inch)
on a 17 monitor 314x250 mm (12.4x9.8 inch).
To meet the different requirements evolved in the MSDOS world (VGA,
SVGA, XVGA, etc.) NEC has developed a MULTISYNC monitor. This monitor
can dynamically change its addressability depending on the frequencies
generated by the graphics controller. Nowadays most monitors provide
this facility although it may be named different. Some monitors provide
only a fixed number of resolutions to select from while others give you
the possibility to program your own mode within the available video
bandwidth. The video bandwidth is a measure for the maximum number of
pixels a monitor can draw per second. A bandwidth of 75 MHz is needed
to provide a 70 Hz refresh rate at 1024x768 while for the same refresh
rate on a 1152x900 screen you will need a bandwidth of 100 MHz.
The number of times a screen is redrawn per second is called the REFRESH
RATE. If this refresh rate is too low we see flicker which can be
tiresome for the eyes. VESA (Video Electronics Standards Association)
has defined 72 Hz as a minimum value for super VGA (800x600) and 70 Hz
for 1024x768. To achieve a refresh rate of F_v for a screen consisting
of X pixels on a row and Y rows (addressability X*Y) the clock rate F_c
of the monitor and graphics card needs to be (approximately):
F_c = 1.36 * X * Y * F_v [MHz]
The horizontal line frequency F_h of the monitor at least:
F_h = F_c / (1.28 * X) [kHz]
The constants 1.36 and 1.28 are computed from the X386 Mode database
compiled by David Wexelblat.
With these formulas we can estimate what clock rates and line
frequencies we need for different addressabilities and refresh rates:
addressability refresh clock line
rate rate frequency
[Hz] [MHz] [kHz]
800x 600 72 47 46 (VESA)
1024x 768 70 75 57 (VESA)
72 77 59
1152x 900 70 99 67
72 102 69
1280x1024 60 107 65 (VESA)
70 125 76
72 128 78
Most monitors use a shadow mask to address individual pixels on the
screen. This shadow mask, which is a thin metal plate perforated with
many small holes and mounted close to the viewing surface, is carefully
aligned so that each of the three electron beams (one each for green,
red and blue) can hit only one type of phosphor dot. This ALIGNMENT is
very critical and can be damaged by careless transportation. Nowadays
flat square tubes are used to provide better picture quality.
Unfortunately this flat square in combination with the alignment of the
shadow mask poses its technical problems to tube manufacturers (lower
yields) what makes them still expensive. It might be wise to sent in
your warranty card and test the monitor as soon as you get it.
There are a lot of other goodies you can be looking (and paying) for:
- available analog or digital controls
Most monitors do provide controls to change the brightness, the
contrast, the position of the picture both horizontal and vertical and
the size of the picture both horizontal and vertical. Some monitors
do provide additional controls to adjust the pincushion and barrel
distortion and the electrostatic charge on the tube (degaussing).
Very few monitors allow you to change the color matching.
- what is the effective (visible) tube diameter
Most monitors do provide significant less than a 17 inch visible screen
diameter. This effective size varies between 15 and 16.5 inch.
- the tube quality
Does the tube provide a flat surface with a special coating to
improve the readability (no-glare) under poor light circumstances?
Tubes providing a Trinitron (trade mark from Sony) tube are in general
more expensive than those without.
Should you be worried about CRT RADIATION? In the Computer Shopper of
93/1 there is a review of Ellen Sugarman's `Warning: The Electricity
Around You May be Hazardous to Your Health' (ISBN 0-89211-00, price $11,
238 pages). Here is a summary of the information found in the brochure
of Multigraph (Nokia) on this subject:
For some time now, people who use computer terminals and personal
computers have been hearing some pretty worrying things about the
radiation, or fields, generated by display monitors. Some people
have even experienced a range of different symptoms when working with
display units, including skin problems and apparent allergic problems.
Although in many cases these reactions are the results of
straightforward work environment factors, including poor ventilation,
they understandably give rise to concern about health hazards.
It must be remembered that all electrical equipment generates
radiated fields of various kinds, including everyday objects like
coffee percolators, electrical typewriters and photocopiers. Display
monitors generate three different kinds of fields: electrostatic,
magnetic and electrical. Though these fields have been clearly
identified today, the biological effects and possible risks are not
yet fully understood. So the possible health hazards, and the concern
felt by many people, have to be taken seriously.
Electrostatic fields:
You may have have noticed that a spark jumps to your hand when you
touch your TV screen. This spark is caused by by the charge on the
surface of cathode ray tube in TV sets. The same is true for display
units. In spite of many years of research there is still no
straightforward answer as to whether electrostatic fields are
dangerous or not. Still, there are fears that they may give rise to
skin and eye complaints.
There are a number of means of reducing the electrostatic field on
the surface of a screen. The solution most commonly adopted today is
the application of a thin coating of a suitable conductive material
to the surface of the screen. This conductive coating is then earthed
through the display unit.
Magnetic fields:
We are constantly surrounded by magnetic fields--static fields like
that of the Earth itself, and the alternating magnetic fields generated
by various kinds of electrical equipment. The latter alternate in turn
in tune with the frequency of the power supply, i.e. normal 50 or 60Hz
(alternations per second). The magnetic fields generated by display
units alternate at the frequency with which the image is refreshed on
the screen. This may be from 50 Hz up to 100000 Hz.
The only effective way of reducing a magnetic field from a display
unit is to counteract it with an opposite field. This can be done in
different ways. Transformers can be located so that their fields
counteract each other. And, in the case of the deflection coils used for
refreshing the image on the screen, compensation coils can be installed
to counteract the magnetic field.
Electrical fields:
Just like magnetic fields, electrical fields are all around us,
generated by electrical cables, light fittings and electrical
typewriters--and by display units. In the latter, they come from the
power supply and from the high-voltage components used to protect
the image on the screen.
Electrical fields are difficult to reduce. When using conductive
coating on the screen surface, material with extremely good conductive
properties is required. If an extra filter is used, it is also
important that the coating on the filter does not reduce the brightness
or contrast of the screen, nor should it create duplicated images
caused by internal reflections.
There are three Swedish levels of `low radiation norms'. The strongest
being the TCO91 norm. Here is what the Nokia brochure tells about them:
MPRI (1987) | MPRII (1990) | TCO-91
Electric Magnetic | Electric Magnetic | Electric Magnetic
-----------------------|--------------------|------------------
400-1kHz n.a. <50nT | <2.5V/m <25nT | <1V/m <25nT
1kHz-5Hz n.a. n.a. | <25V/m <250nT | <10V/m <200nT
0 Hz <500V n.a. | <500V n.a. | <500V n.a.
The measurement methods differ for each different norm. In the
MPRI norm according P-P at 30 cm, in the MPRII norm according RMS at 50
cm and TCO-91 according RMS at 30 cm (except the magnetic value at
400 -1kHz which is measured at 50 cm). The radiation of Nokia monitors
are well below the rigorous limits set in 1991 by the Swedish
Confederation of Professional Employees (TCO).
While the TCO91 norm concentrates on your personal protection during
the usage of the monitor the TCO92 norm also does minimize the
energy consumption by providing an auto power down function.
More information about the TCO norms can be obtained directly from:
Tj"anstem"annens CentralOrganisation
Linn'egatan 14
P.O. Box 5252
S-102 45 Stockholm
Schweden
As important as the monitor itself is the GRAPHICS CONTROLLER that we
are going to use. Most modern boards use a dedicated processor to speed
up the process of mapping the framebuffer to the monitor screen without
disturbing the central processor. To support the 70 Hz refresh rate
VESA standard your graphics card should have a minimal clock rate of 75
MHz for the 1024x768 mode or 100 MHz if you prefer the 1152x900 mode.
The card should have minimal 1 MB on-board memory to support 256 colors
in both modes. The standard X-server of 386BSD UNIX does not support
all kind of chipsets. ET4000 based VESA boards with 1MB DRAM are not
super fast (about 8k xstones) but very affordable today and supported by
the standard X386. In stead of dynamic memory (DRAM) video memory
(VRAM) has the advantage that it is dual ported so that the video
processor and central processor can simultaneously access the
framebuffer. Unfortunately ET4000 chipsets does not have VRAM based
versions. But the performance of an ET4000 board can be improved by a
factor of two by using local bus motherboards.
If graphic performance is of great importance for you then consider a S3
based board (I heard that OS/2 does not support S3 cards ...).
Currently the standard X386 server does not support these cards but
there is a PD XS3 beta version available (see advertisements on
comp.unix.bsd). Some of these S3 cards, the ones that have a 8C911 or
8C924 chipset, do support video memory. The Orchid Fahrenheit 1280
(8C911 chipset) is VESA compatible and does support a refresh rate of 70
Hz in 1024x768. The Actix GraphicsENGINE Ultra (8C924 chipset) does
even provide a 72 Hz refresh rate in the 1024x768 mode and comes in a 1
MB and 2 MB version. To give you an impression what performance other
UNIX systems and X-terminals can provide here some xbench results I have
measured:
computer/terminal X*Y xstones
SGI (4D/310VGX) 1280x1024 83106 (21" color X-monitor)
Tektronics XP27 1150x 900 61625 (17" color X-terminal)
NCD-17c 1024x 768 34228 (17" color X-terminal)
Xvision (486DX50,8C911) 1024x 768 32276 (17" color MSDOS X-emulator)
NCD16 1024x1024 13728 (16" b/w X-terminal)
2. Overview
------------
In the next table I have put together the MULTISYNC non-interlaced
monitors that are available in Europe and/or the USA. It contains an
overview of important data as video bandwidth, maximum horizontal line
frequency, dot pitch, the radiation norm and the price. Most data is
derived from testreports in PC Magazine, the CHIP-special about
`Grafikkarten & Monitore' (92/2) and the brochures I got from some Dutch
distributors. The prices are taken from Computer Shopper (93/1), PC
Professionell (93/1), CHIP 92/8 or a cheaper/other source if that was
available. If the data was not available to me I have left it blank. A
column containing `n.a.' means this feature is not available.
The table is divided in three parts. Part one contains monitors that
can refresh a 1280x1024 screen 70 times per second or more. It seems
that this feature is a little bit `overdone' for a 17" monitor and you
will need a graphic card with 2MB video RAM. Part two contains the
monitors that support 1280x1024 in 60Hz and 1024x768 in 70 Hz. Part
three contains monitors that can only handle 1024x768 in 70 Hz.
monitor type band line dot radiation street price
width freq level
(MHz) (kHz) (mm) (norm) ($USA) (DM)
------------ 70 Hz 1280x1024 --- line frequency >= 75 kHz -----------
EIZO (Nanao) T560i 120 80 .26 MPRII 1899 3480
NEC 5FG 135 79 .28 MPRII 1249 2577
Relisys RE1776 125 76 .26 1500
Octek CM-1790M 125 76 .31 2045
TAXAN M875 LR 75 .28 MPRII
------------ 60 Hz 1280x1024 --- line frequency >= 64 kHz -----------
Vortec VT-17HI 110 68 .26 2800
MAG 17H 100 68 .26 1149 2388
CONRAC Neptun 9317 110 66 .26
Philips 4CM6099 110 66 .26 MPRII 2800
Tatung CM-17MBD 100 66 .26 1599
Goldstar 1720 110 65 .26
Samsung CCB 7577 100 65 .26
CTX CPS-1760 DF 100 65 .28 MPRII 855 1500
Toshiba R17CM01 100 65 .28 MPRII 1900
CTX CPS-1760 100 65 .31 775
EIZO (Nanao) F550i 80 65 .28 MPRII 1149 2366
Idek MF 5317 60 65 .31 1099
Viewsonic 7 110 64 .28 1049 2400
AOC CM-735 110 64 .28
Miro C17 T 110 64 .26
Nokia 447B 110 64 .26 TCO91 3099
Seiko CM-1760LR 100 64 .25 MPRII 1139
Panasonic TX-1713 100 64 .28
Miro C17 T 100 64 .25
Panasonic TX-1703MA 100 64 .28 MPRII
HP Ultra VGA 85 64 .28 MPRII 949
Mitsu. Diamond pro17 80 64 .28 MPRII 1129
Qume QM 870 LR 64 .26
Olivetti DSM 27-117 64 .26 MPRII
VDO HD-667 64 .28 MPRII
Hitachi 17MVX 64 .28 MPRII
------------ 70 Hz 1024x 768 --- line frequency >= 57 kHz -----------
VISA MC-8740 80 60 .26
AcerView 76 80 60 .28 MPRII 1449
IBG AV 76 LR 80 60 .28
Goldstar 1710 75 60 .28
Profex VCM 1731 80 60 .31
VISA MC-8730 80 60 .31
Sampo KDM 1766 80 60 .31
Compac Qvision 170 75 58 .25 MPRII 2600
Mitac M1758 85 58 .31
Sony CPD-1604S 60 57 .25 MPRII 995
Epson Prof. series 70 57 .26 1539
Epson Prof. series 70 57 .26
Idek MF 5217 55 57 .28 859 1450
3. Test reports
---------------
Next monitors were tested by PC Magazine (`17-inch displays, A Better
View of Windows', 92/6) and PC Professionell (`Alle 17-Zoll Monitore im
Vergleich', 92/6). The MAG MX17H and the EIZO F550i got an editor's
choice nomination, the Viewsonic and NEC 5FG got an honorable mention in
the PC Magazine test. The EIZO T560i, NEC 5FG and Nokia 447B got an
`Empfehlung der Redaktion' from PC Profesionell while the EIZO F550i,
Panasonic TX 1703MA and Viewsonic 7 were mentioned as `brauchbare
Alternatieve'.
You can see that a high bandwidth and a small dot pitch not always means
that the quality and price is what you should expect. The Relisys had
problems with roping and with maintaining a consistent brightness out to
the edges of the display, while the EIZO with its bandwidth of only 80
MHz and 0.28 pitch got a nomination. If the monitor you want to buy is
on this list get a copy of the PCM or PCP article. It summarizes all
features these monitors provide.
monitor type bandwidth dot pitch diagonal PCM PCP
(MHz) (mm) (inch) ($) (DM)
Relisys RE1776 135 0.26 16.0 1499
NEC 5FG 135 0.28 15.3 1699 4549
EIZO (Nanao) T560i 120 0.26 16.1 5130
MAG MX17H 120 0.26 15.5 1549
Nokia 447B 110 0.26 16.3 3099
Viewsonic 7 110 0.28 16.0 1399 2295
Miro C1766 110 0.26
Seiko CM 1760LR 100 0.25 16.5 1599 3990
Tatung CM-17MBD 100 0.26 15.7 1599
Mitsubishi Diamond Pro17 100 0.28 15.8 1720
Toshiba R17CM01 100 0.28 16.0 1495
CTX-1760 100 0.31 16.0 1399
Panasonic TX-1703MA 100 0.28 16.1 2999
Mitac M1758 85 0.31 15.3 999
HP Ultra VGA 85 0.28 15.8 1449
EIZO (Nanao) F550i 80 0.28 15.8 1749 3400
AcerView 76 80 0.31 15.6 1079
Epson Prof. series 70 0.26 16.3 1539
Sony CPD 1604S 60 0.25 16.4 1799
IDEK MF-5317 60 0.28 16.2 1495 4392
IDEK MF-5217 55 0.28 16.1 3762
IDEK MF-5117 55 0.28 16.1 2100
The column `diagonal' contains the effective screen size, the visual
part of the screen. The columns `PCM' and `PCP' give the list prices as
provided by PC Magazine and PC Profesionell.
I wish you all a bigger view!
--Piet
internet: rcpt@urc.tue.nl | Piet Tutelaers
bitnet: rcpt@heitue5.BITNET | Computer Center Room RC 1.90
phone: +31 (0)40 474541 | Eindhoven University of Technology
fax: +31 (0)40 434438 | P.O. Box 513, 5600 MB Eindhoven, NL