jthornto@ee.ubc.ca (Johan Thornton) (05/17/91)
Does anyone know either - where to get - how to build a clear touch screen to fit over a monitor. It doesn't have to have to have very high resolution--4 by 4 would be ok. One idea I had was to run some small wires across the screen and essentially use the classic capacitive touch-switch circuit. Thanks. -- Johan Thornton (but my friends call me jthornto@ee.ubc.ca)
whos@ddsw1.MCS.COM (Ben Feen) (05/18/91)
In article <1656@fs1.ee.ubc.ca> jthornto@ee.ubc.ca (Johan Thornton) writes: >Does anyone know either > >- where to get >- how to build > >a clear touch screen to fit over a monitor. It doesn't have to have >to have very high resolution--4 by 4 would be ok. > >One idea I had was to run some small wires across the screen and essentially >use the classic capacitive touch-switch circuit. > Touch screens are not touch-operated, or at least the HP screens I've seen aren't. They are based on small transmitters and sensors around the screen's border. When you interrupt the beams crossing the screen, the computer knows the X-Y coord's of your finger. The wires idea is cute, but there are two problems: 1: You'd have to prevent the "X" wires from shorting with the "Y" wires, but still have them close enough to touch two at once. 2: Who wants wires on their screen? (BTW: I THINK the above description of a touch screen is right. If not, feel free to correct me, but direct flames to dev/nul. -- whos@ddsw1.MCS.COM | I don't know, who's at DDSW1? | whos@ddsw1.MCS.COM! I asked YOU who's at DDSW1! Ok, there's a guy at DDSW1, right? | Right! Who? | Exactly! | What? | No, he's at lll-winken. | Where? | No, What! | I don't know! | He's at gargoyle. | Who? | No, he's at DDSW1.MCS.COM!
mzenier@polari.UUCP (Mark Zenier) (05/19/91)
In article <1991May18.025326.375@ddsw1.MCS.COM> whos@ddsw1.MCS.COM (Ben Feen) writes: >In article <1656@fs1.ee.ubc.ca> jthornto@ee.ubc.ca (Johan Thornton) writes: >>Does anyone know either >>- where to get >>- how to build >>a clear touch screen to fit over a monitor. It doesn't have to have >>to have very high resolution--4 by 4 would be ok. >Touch screens are not touch-operated, or at least the HP screens I've seen Fluke made a crt display with a touch switch array over the screen. It was all clear plastic film. Either the wires were very small or the x/y "wires" were thin films. >The wires idea is cute, but there are two problems: >1: You'd have to prevent the "X" wires from shorting with the "Y" wires, >but still have them close enough to touch two at once. Little bumps in the film layers kept adjacent switch positions isolated. >2: Who wants wires on their screen? There was another touch screen (Marconi?) that had fixed postions with two parallel wire segments on the surface of the glass. The operator touched the two wires. Since this was an air traffic control application, they must have relied on the conductivity of sweaty fingers. Mark Zenier markz@ssc.uucp mzenier@polari.uucp
sasrer@unx.sas.com (Rodney Radford) (05/20/91)
In article <1991May18.025326.375@ddsw1.MCS.COM> whos@ddsw1.MCS.COM (Ben Feen) writes: >In article <1656@fs1.ee.ubc.ca> jthornto@ee.ubc.ca (Johan Thornton) writes: >>Does anyone know either >> >>- where to get >>- how to build >> >>a clear touch screen to fit over a monitor. It doesn't have to have >>to have very high resolution--4 by 4 would be ok. >> >>One idea I had was to run some small wires across the screen and essentially >>use the classic capacitive touch-switch circuit. >> > >Touch screens are not touch-operated, or at least the HP screens I've seen >aren't. They are based on small transmitters and sensors around the >screen's border. When you interrupt the beams crossing the screen, the >computer knows the X-Y coord's of your finger. The wires idea is cute, but >there are two problems: > >1: You'd have to prevent the "X" wires from shorting with the "Y" wires, >but still have them close enough to touch two at once. >2: Who wants wires on their screen? > I have a surplus touch sensitive terminal from an old Plato educational system that used the idea of "X" and "Y" wires that were shorted together when you press at (or near) their intersection. The terminal I have has a 16x16 resolution giving 256 specific touch points. And no, you can't see the small wires (their are very thin - near the size of human hair). The display was given to me, and I have not done anything with it yet, other than play with the builtin in test program. As you press each of the 256 areas, a portion of the screen toggles on/off so you can verify that it works OK. The screen resolution is 512x512 black&white. The only problem is that it uses a non-standard bit-stream protocol (I have no specs on the software that controlled it but the person who gave it to me thought that is was a 17bit in, 21bit out serialized format!!). This equipment is now junk, but it was 'state of the art' only a few years ago when I saw it demo'ed at the Worlds Fair in Knoxville. My how things change.... -- +-----------------------------------------------------------------------------+ | Rodney E. Radford Computer Graphics Imaging sasrer@unx.sas.com | | (919) 677-8000 SAS Institute, Inc. | ------------------------------------------------------------------------------+