RE: Touch-Pad ESD immunity
-Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Wednesday, January 02, 2002 8:34 PM To: emc-p...@majordomo.ieee.org Subject: Re: Touch-Pad ESD immunity I read in !emc-pstc that Gary McInturff Gary.McInturff@worldwidepackets .com wrote (in 917063bab0ddb043af5faa73c7a835d40c0...@windlord.wwp.com ) about 'Touch-Pad ESD immunity', on Wed, 2 Jan 2002: Do you have denounce circuitry on the input of the touch pad The spell-checker demon strikes again! (;-) -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk After swimming across the Hellespont, I felt like a Hero. Too long of a holiday, as I'm starting the new year with insufficient alphabetical noise immunity! I actually did a Google search on denounce circuitry. Ed Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military Avionics EMC Services Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: Touch-Pad ESD immunity
I read in !emc-pstc that Gary McInturff Gary.McInturff@worldwidepackets .com wrote (in 917063bab0ddb043af5faa73c7a835d40c0...@windlord.wwp.com ) about 'Touch-Pad ESD immunity', on Wed, 2 Jan 2002: Do you have denounce circuitry on the input of the touch pad The spell-checker demon strikes again! (;-) -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk After swimming across the Hellespont, I felt like a Hero. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: Touch-Pad ESD immunity
Well, one of the less obvious things is what does your system do to detect a true mouse pad contact? Do you have denounce circuitry on the input of the touch pad (or keyboard lines), do you sample a couple of times to see if the input stays there (thumbs are still much slower than ESD pulses). If the touch pad does provide a ground path for the ESD currents how does your equipment handle that current to insured it doesn't get into your electronics? The touch pad can certainly be the culprit and about the only way to tell is buy physically examining the pad to see how they are grounding things and using your judgment to see if its adequate. But even a well done touch pad can appear to be a problem if you have not protected the input lines, or checked for hung input states etc. Over time, touch pads also become more sensitive to the intended tapping function. After a few months I have to use and run a program that suppresses taps altogether. If I don't and the mouse pointer happens to be over the send button, for example, I will often get partially completed e-mails sent out when the old fat thumbs happen to lightly touch the touch pad itself. Telling the prospective vendor that you won't be using their touch pad and why, may offer some relief as well. Even if it does look at how well you are protecting your system from the vagrancies of ESD from the pad or a keyboard. Considering what keyboards and touch pads sell for you won't find those folks putting a whole bunch of money into hardening them. Good luck Gary -Original Message- From: Chris Maxwell [mailto:chris.maxw...@nettest.com] Sent: Wednesday, January 02, 2002 1:47 PM To: EMC-PSTC Internet Forum Subject: Touch-Pad ESD immunity Dear Ann Landers, I've always had trouble with peripherals. Keyboards and mice that were CE marked and looked like such good prospects have mostly turned out to be fickle. Well, I've been involved with a touchpad for about five months now. When I first bought it, we were so happy. Whenever we were together it, it could read my mind. A tap of my finger and it knew just what to do. And then this ESD gun comes along. One zap and BOOM! The touchpad turns its back on me. It won't respond at all! I tried talking to it...but it just gave me the cold shoulder. I suggested counseling...still no response. I threatend to go and get a mouse...no response. Well, I finally had to just take a deep breath and go through with it. I cycled power. Well it now responds to me... but I don't know if I'll ever trust it around an ESD gun again. I don't know if our relationship will ever be the same. Signed Out of touch in New York OK OK The real question is... does anybody have some words of advice regarding touchpads. I am testing a unit which consists of a keyboard/touchpad combination. The touchpad is approx 1.5 x 1.5 and is able to sense a sliding or tapping finger. The touchpad is used to perform all of the functions that a mouse typically performs. I am assuming that it has some sort of capacitive sense circuit which can tell when your finger slides across the pad or taps on the pad. I have one that gets all out of whack with 8KV ESD. i.e. the touchpad becomes unresponsive and it stops software execution in our host system. Unfortunately, this is one of those instances where we don't build the keyboard/touchpad; so my bag of fix tricks is limited. Probably limited to seeing if another manufacturer produces a keyboard/touchpad with better performance. Or, am I slamming my head against the wall on this one? The keyboard/touchpad is already CE marked by its manufacturer. Is this typical? Are all touchpads (even CE marked ones) ESD sensitive? Do I just live with it? Am I over-testing this touchpad? Overall... I have had REALLY bad experiences with CE marked keyboards and mouses. Now I have trouble with our first touchpad. We typically use a capacitive filter on our inputs and we typically put a ferrite on the cable...yet still trouble. Is this typical of what others see? Any words of advice, experience... would be appreciated. Chris Maxwell | Design Engineer - Optical Division email chris.maxw...@nettest.com | dir +1 315 266 5128 | fax +1 315 797 8024 NetTest | 6 Rhoads Drive, Utica, NY 13502 | USA web www.nettest.com | tel +1 315 797 4449 | --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher
Touch-Pad ESD immunity
Dear Ann Landers, I've always had trouble with peripherals. Keyboards and mice that were CE marked and looked like such good prospects have mostly turned out to be fickle. Well, I've been involved with a touchpad for about five months now. When I first bought it, we were so happy. Whenever we were together it, it could read my mind. A tap of my finger and it knew just what to do. And then this ESD gun comes along. One zap and BOOM! The touchpad turns its back on me. It won't respond at all! I tried talking to it...but it just gave me the cold shoulder. I suggested counseling...still no response. I threatend to go and get a mouse...no response. Well, I finally had to just take a deep breath and go through with it. I cycled power. Well it now responds to me... but I don't know if I'll ever trust it around an ESD gun again. I don't know if our relationship will ever be the same. Signed Out of touch in New York OK OK The real question is... does anybody have some words of advice regarding touchpads. I am testing a unit which consists of a keyboard/touchpad combination. The touchpad is approx 1.5 x 1.5 and is able to sense a sliding or tapping finger. The touchpad is used to perform all of the functions that a mouse typically performs. I am assuming that it has some sort of capacitive sense circuit which can tell when your finger slides across the pad or taps on the pad. I have one that gets all out of whack with 8KV ESD. i.e. the touchpad becomes unresponsive and it stops software execution in our host system. Unfortunately, this is one of those instances where we don't build the keyboard/touchpad; so my bag of fix tricks is limited. Probably limited to seeing if another manufacturer produces a keyboard/touchpad with better performance. Or, am I slamming my head against the wall on this one? The keyboard/touchpad is already CE marked by its manufacturer. Is this typical? Are all touchpads (even CE marked ones) ESD sensitive? Do I just live with it? Am I over-testing this touchpad? Overall... I have had REALLY bad experiences with CE marked keyboards and mouses. Now I have trouble with our first touchpad. We typically use a capacitive filter on our inputs and we typically put a ferrite on the cable...yet still trouble. Is this typical of what others see? Any words of advice, experience... would be appreciated. Chris Maxwell | Design Engineer - Optical Division email chris.maxw...@nettest.com | dir +1 315 266 5128 | fax +1 315 797 8024 NetTest | 6 Rhoads Drive, Utica, NY 13502 | USA web www.nettest.com | tel +1 315 797 4449 | --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
