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AssigneeCommissariat a l'Energie Atomique
InventorsMarcel Audoin, Jean-Marc Fedeli, Robert Poujois
Estimating the term…
Apparatus for suppressing interference in a capacitive keyboard. Unconditioned operating signals from receiving lines are passed into a subtractor, which establishes the difference between the signal present on a reference line in the keyboard and supplies, at the output, a conditioned operating signal which is free from any unwanted electromagnetic component which may have entered the structure. In addition, in order to determine which of several keys is supplying the highest signal, operating signals corresponding to particular receiving lines are scanned in sequence to determine which has the highest amplitude. As the operating signal corresponding to each successive key is scanned, its voltage is compared with a previously-stored voltage for an earlier-scanned key. If a higher voltage is detected, the voltage and key address are stored in place of the previously-stored values.
An apparatus for the suppression of interference in a capacitive keyboard of the type including a series of sensitive keys on an outer surface accessible to a user, each key having a transmitting electrode excited by an alternating signal supplied by a transmitting line, and a receiving electrode selectively capacitively coupled to the transmitting electrode and connected to supply a receiving line, the receiving lines providing a corresponding set of unconditioned operating signals having amplitude variations dependent on the effect of the possible presence of the finger of a user on the sensitive key,
Dependencies are inferred from the claim text.