screen-image-to-projector-screen devices (124)

Tue, 7 Mar 89 19:17:29 EST

Humanist Mailing List, Vol. 2, No. 682. Tuesday, 7 Mar 1989.

(1) Date: 7-MAR-1989 09:04:59 GMT (21 lines)

(2) Date: Tue, 07 Mar 89 09:45:05 GMT (13 lines)
From: Mike Norris <MNORRIS@IRLEARN>
Subject: Re: Queries (64)

(3) Date: Tue, 7 Mar 89 03:42:25 EST (35 lines)
From: David.A.Bantz@mac.Dartmouth.EDU
Subject: Re: screen-image-to-projector-screen device?

(4) Date: Tue, 7 Mar 89 11:29 EST (27 lines)
From: Terrence Erdt <ERDT@VUVAXCOM>
Subject: LCD panel displays

(1) --------------------------------------------------------------------
Date: 7-MAR-1989 09:04:59 GMT

OHP Displays.

The first examples of OHP displays sought by John Hurd were good
ideas in search of development. The characters were badly affected
by heat and also were rather faint and lacking in contrast for large
lecture theatres. They were effectively in monochrome only despite
misleading sales hype.

More recent models have tried to overcome these drawbacks but with
limited success. Their resolution is also better and approaches VGA
standards in some cases. They cost about 1000 pounds sterling but
are becoming cheaper. There are various suppliers. Kodak produced
an early model and I have a flyer from "In Focus Systems " Tualatin,
Oregon on my desk but there are certainly other suppliers. I cannot
recommend a best buy.

John Roper, UEA, Norwich, UK
S200 @ UK.AC.UEA.CPC865
(2) --------------------------------------------------------------18----
Date: Tue, 07 Mar 89 09:45:05 GMT
From: Mike Norris <MNORRIS@IRLEARN>
Subject: Re: Queries (64)

Re John Hurd's query about screen-to-OHP devices:

We've used both the Kodak Datashow and the Apollo PC-9600 Presenter.
The latter has worked out fine, and can be used with PC, Apple ][
or Macintosh. It comes from Apollo Audio Visual, New York
(516 467-8033).

(3) --------------------------------------------------------------49----
Date: Tue, 7 Mar 89 03:42:25 EST
From: David.A.Bantz@mac.Dartmouth.EDU
Subject: Re: screen-image-to-projector-screen device?

<<From: John C. Hurd HURD@UTOREPAS
Subject: screen-image-to-projector-screen device?

Some time ago I read of a liquid-crystal display device which was
designed to sit on an over-head projector so that the output of a
microcomputer could be seen by a class. Now I have lost the
reference. Does anybody know offhand who makes it? Has anyone
had experience with it? Proleptic thanks.>>

There are several marketed; some older models had low contrast and quickly
decayed in the heat of an overhead; newer ones are quite useable. We've had
experience with the Kodak DataShow and the Sharp QA50, both of which give
sharp readable images even in a meduim-sized auditorium, assuming
overhead/ambient light is high enough.
Both units require installing a video adaptor on a Macintosh; the Sharp will
connect directly to the video output of a PC. The Kodak is strictly b&w, the
Sharp will display grey levels, and you can varry the mapping of colors to
grey level (I've not actually seen this in operation).

The Kodak is simplicity itself; the only adjustment is for overall contrast;
rock stable; very quiet. The Sharp has adjustments for synching with various
video signals and for color-grey mapping; it's possible to spend a lot of time
getting the adjustments set properly; usually requires a minor adjustment
every few minutes in use; it has an annoyingly loud fan, but then so will your

These two models, unlike many others I've seen (Dukane, nView & others I can't
remember) have very little coloration, only modest persistence leading to
ghosting (I wouldn't want to display rapid animations, but anything else is
fine), and, as I said, good contrast.
(4) --------------------------------------------------------------32----
Date: Tue, 7 Mar 89 11:29 EST
From: Terrence Erdt <ERDT@VUVAXCOM>
Subject: LCD panel displays

John Hurd asks about LCD projectors (the flat panel displays that
allow an overhead projector to be used with a pc). There are a number
of them being sold, some now with a rudimentary color output. I
have had experience with the Telex Magnabyte display. The setup is
easily performed: a short card goes into an available slot in the
pc, and a cable is attached to the panel, which is then set upon
a standard overhead projector.

Unfortunately the Magnabyte (and I understand that the same is
commonly true among LCD projectors) loses picture quality rather
quickly; apparently the overhead heats up the panel. In any case,
after about fifteen minutes after the machine is switched on,
a bright spot emerges in the center of the projected picture.

Several manufactures claim to have licked the low resolution and
heat problems, and now at least one company is producing an EGA
compatible display. Perhaps other Humanists have found
more reliable display devices.

Terrence Erdt erdt@vuvaxcom (215) 645-4670
Villanova Univ.
Villanov, PA USA