Resolved - patent examiner independently struck down claims - see comment below.

Does anybody know of any prior art related to US20110128257 ?

The patent US20110128257 claims a provisional application date of Nov 29 2009.

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1 Answer 1


It seems that there is prior art at least for claims 1 and 2:

Huang, C.F. Precise Location of Touch Panel by Employing the Time-Domain Reflectometry. SID Symposium Digest of Technical Papers, 40(1), June 2009, pp. 1291-1293.

and possibly

Collins, Ryan V. Methods and apparatus for receiving user input via time domain reflectometry. US-Patent 2004/0239616 A1

Furthermore, the general principle of touch sensing using TDR has already been described in 1964:

"In exposed circuits one can touch the line to produce an added echo. Then, by running the point of contact along the line till this added echo coincides with the system echoes, one can literally put his fingers on the troubles. In a coaxial cable, one can produce a reflection by squeezing the cable."

Oliver, B. M. Time Domain Reflectometry, HP Journal 15(6), 1964.

Edit: According to the Public PAIR, the patent examiner struck down claims 1-5 as being already described by Kozik et al. (US 5149918). The patent only refers to optical TDR now.

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