Maybe this is overly simplistic, but there are a zillion (trust me, I'm an engineer), capacitive touch pad styli out there to choose from. Since they clearly "simulate" a human finger in real operation, why not just include one or more of them in your test fixture design? Of course you still need a few hundred pF from the body of the stylus to ground to simulate a big human body full of salt water, but mechanical design is vastly simplified. This one works well and has replaceable tips for when things wear out:
http://musemee.com/us/index.php Respectfully, Brent DeWitt Milford, MA -----Original Message----- From: Sundstrom, Mike [mailto:[email protected]] Sent: Thursday, October 09, 2014 3:02 PM To: [email protected] Subject: Re: [PSES] Human fingertip capacitance. In a long ago job I learned the two 480K Ohm resistors in the ESD gun ground lead was to simulate the human body (whole body). Something about shaping the current pulse or flow to ground? Michael Sundstrom Garmin Compliance Engineer 2-2606 (913) 440-1540 It's not what you look at that matters, it's what you see. Henry David Thoreau -----Original Message----- From: Brian Oconnell [mailto:[email protected]] Sent: Thursday, October 09, 2014 11:41 AM To: [email protected] Subject: Re: [PSES] Human fingertip capacitance. Do not believe that it is the 'capacitance' of the human appendage per se, but the interference with the screen's field. Suspect that the Emperor's search engine would reveal much more, but an ap note used in a past project is here: www.ti.com/lit/an/slaa363a/slaa363a.pdf Brian From: Gary McInturff [mailto:[email protected]] Sent: Thursday, October 09, 2014 9:14 AM To: [email protected] Subject: [PSES] Human fingertip capacitance. Trying to set up a jig to test some capacitive touch-panels. It's an automated probe that disturbs the capacitive field of the sensor - but I'm clueless what kind of value to shoot for. I thought about the ESD gun capacitance but I don't know if that actually matches a human fingertip - or it's the whole body, or that the capacitance of the body of the ESD gun itself is used to calibrate to some human figure tip capacitance. I've got some research to do but does anybody have a starting point and a reference for the capacitance of an average human fingertip. I have the EE working the design to go back to the component supplier but haven't heard back from them yet. Thanks Gary McInturff Reliability/Compliance Engineer Esterline Interface Technologies Featuring ADVANCED INPUT, GAMESMAN, and LRE MEDICAL products 600 W. Wilbur Avenue Coeur d'Alene, ID 83815-9496 Toll Free: 800-444-5923 X1XXX Tel: (208) 635-8 Fax: (208) 635-8 - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
