trl@tokugowa.UUCP (the GOOD Doctor) (11/08/89)
Problem: I am currently working on a project involving the conversion of
of a touch based data entry system from a PDP 11/44 to a VAX 6320.
The touch units currently in use on the PDP 11/44 will not, for
various reasons, suffice for use on the system under development.
Therefore I need to find a new touch screen which will work.
Conditions :
a) May be either an integrated touch screen (preffered) OR
a terminal with touch add on unit.
b) Display area must be of a reasonable size.
(Current size is 12" diag.)
c) Should be compatible with standard VTxxx class terminals.
d) Needs to have secondary serial I/O for interface to other
devices.
Any and all suggestion, pointers and/or helpfull comments greatly appreciated!
Many Thanks,
Thomas Luce.johnk@opel.uu.net (John Kennedy) (11/14/89)
In article <715@tokugowa.UUCP> trl@tokugowa.UUCP (the GOOD Doctor) writes: > > Therefore I need to find a new touch screen which will work. > >Any and all suggestion, pointers and/or helpfull comments greatly appreciated! > You didn't say whether your terminals could be PC's. If so, read on - About a year ago, I was working on a project which needed a touch-entry screen for air traffic control applications. We looked at several technologies of touch entry: resistive, capacitive, infrared beams, etc. Each had advantages and disadvantages, and users were very opinionated about the cons of each: abrasion, parallax errors, whether or not you could use a pencil rather than a finger, etc. The approach we ended up with seemed to make every one happy. That was the use of IR beam technology over a flat panel CRT. Normally, the IR approach utilizes an array of infrared LEDs and photocells along all four edges of the CRT screen. Its disadvantage in the past was that the LEDS and sensors had to be placed at a sufficient height above the plane of the screen in order to see over the "horizon", as presented by the curved glass of the CRT. This caused a massive parallax problem if the user was not directly in front of the screen. Zenith now makes a CRT, EGA and VGA compatible, whose front glass is completely flat. The IR device is an overlay, which is just a frame that sticks onto the bezel surrounding the glass. This overlay can now rest much closer to the face of the CRT than before, thus greatly reducing the parallax problem. The overlay is like a picture frame, containing no glass, plastic, etc. in its center. It just surrounds the glass of the CRT. The overlay is made by Carroll-Touch, I think in the Dallas area. It seems that they are a division of a larger company, like AMP, or somebody. Its interface to its host is via a configurable RS-232 interface. It resolves multiple beam breaks by reporting the center of the beams being brokes, and rejects simultaneous entries in non-contiguous areas. What it reports is programmable, such as whether to report makes and breaks, fingers sliding around, etc. I guess the major disadvantage of this system was that the Zenith monitor comes with a blue anti-glare coating on the glass, as you would find on a camera lens. It grows fingerprints at the slightest touch. Combine that with a system that you're supposed to touch, and you find yourself cleaning glass often. Nonetheless, the system was demonstrated a year ago at the Air Traffic Controllers Association conference, to rave reviews. (ok, i don't work for either of the companies whose products got plugged ) John -- John Kennedy johnk@opel.uu.uunet Second Source, Inc. Annapolis, MD