Wow, My first suggestion would be to have the Australians play more poker. Cards aren't susceptible to ESD.
But, I guess it's video games that they want. I can relate a couple of tricks that I have either heard of, or tried. If your display is not a touch screen; then you can try some different display window solutions, including an Indium Tin Oxide (ITO) coating that will help dissipate the static on the screen itself. There are even windows with wire mesh built in; but the mesh is very apparent to the user. If in doubt, this can be prototyped by putting some cheap wire mesh, or holey Aluminum foil over the display just as an experiment. Discharges to grounded areas around the display (what I call a bezel) have caused problems with our equipment before. With this one, I would suggest thinking about why this is a problem (i.e. try to imagine the failure mechanism). For instance, is there a secondary discharge from this bezel to a cable leading to the LCD? Or to one of the LCD drive circuits? Or to the LCD's chassis itself? Is the ESD to the bezel radiating a field to either the LCD drive circuits or a cable leading to the LCD? Could the ESD to the bezel be causing a ground, power or logic bounce between the LCD and the rest of the unit? Is the ESD current on the bezel partially flowing through LCD drive circuits on its way to Earth? With a problem like this, I usually try to "shotgun" one of two approaches, either bonding everything together or isolating everything as completely as possible. For instance a "shotgun" at bonding everything together would include trying to bond the LCD's metal chassis, the bezel and the LCD drive circuit's digital ground together at many locations around the periphery of the LCD (every inch or two). A "shotgun at isolating everything would include: Isolating the LCD drive circuit's digital ground from the bezel. Shielding the LCD drive cables from any secondary ESD-induced fields from the bezel (a Reynolds wrap shield over the cable, bonded to the display chassis and digital ground). Ensuring that there is enough spacing or insulation from the bezel so that a secondary discharge won't occur to the drive cable or LCD itself. Grounding the LCD's metal bezel to the LDC drive circuit's digital ground. If you've done all of that; then you have a bezel that is connected to Earth ground and a display with drive circuits referenced to an isolated digital ground. You could then play with the connection between the digital ground and Earth ground. For instance, you could try connecting them at one point near where the unit's Earth ground is made (usually the appliance inlet). Note that in either "shotgun" case mentioned above, if you end up using a window coating or shielded window; I would bond this coating or shielding to the Earthed bezel. Hope I've helped, best regards. Chris Maxwell Design Engineer Nettest From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Thursday, January 29, 2004 7:54 PM To: John Woodgate Cc: emc-pstc @ majordomo . ieee . org Subject: Re: Re: LCD ESD issues In this case, the Australian National Gaming Standard stipulates that no noticable effects are acceptable up to 15kV air discharge. This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ieee-pses.org/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
