| ??? 05/14/10 08:44 Read: times |
#175877 - Touch Sense Patents Responding to: ???'s previous message |
ST provide a pretty good description of the principles used in their capacitive Touch Sense Software Library (TSSL):
Application Note AN2927: "RC acquisition principle for touch sensing applications" http://www.st.com/stonline/.../15323.pdf See also other "Touch sensing" documents at http://www.st.com/mcu/modul...cs&FAM=113 - including: TN0075 Technical note, "TSSL frequently asked and anticipated questions (FAAQs)" said:
The RC acquisition method is based on a 1976 US Patent from now (sic) in the public domain.
www.st.com/stonline/products/literature/tn/15355.pdf I think the patent in question is: Willis A. Larson, "Touch actuated electronic switch including protection from high potential electricity" Patent number: 3992634 Filing date: May 9, 1975 Issue date: Nov 16, 1976 http://www.google.com/patents?i...q=&f=false Texas Instruments refer to another Patent: Robert E Marin, Roger K Simonson, "Capacitive Keyswitch Sensor and Method" US Patent #3931610, 1976 http://www.google.com/patents?i...&q&f=false See: http://focus.ti.com/lit/ml/slap119a/slap119a.pdf Also: http://focus.ti.com/lit/an/slaa363a/slaa363a.pdf |
