Multi-touch system and method for emulating modifier keys via fingertip chords

  • US 6,570,557 B1
  • Filed: 02/10/2001
  • Issued: 05/27/2003
  • Est. Priority Date: 02/10/2001
  • Status: Active Grant
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First Claim
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1. A multi-touch surface apparatus that interprets 4-finger chords performed concurrently with other input activity as modifiers of that input activity, thereby avoiding awkward thumb or pinky reaches for conventional modifier keys, reducing hand strain and reducing the tendency of hands to drift off of home row, the apparatus comprising:

  • multiple-touch sensing means that reports the locations and times of finger contacts with a surface;

    modifier configuration means that establishes modifier zones as horizontal bands across the surface and associates each modifier zone with one or more modifier types;

    synchronization detection means that scans for modifier chord touchdowns consisting of substantially simultaneous touches by four and no more than four digits of a hand;

    modifier zone selection means that selects modifier types for the chord according to which modifier zones said simultaneous touches fall within;

    chord cancellation means that cancels a modifier chord if the remaining unsynchronized digit from its hand touches before other modifiable input activity commits the chord;

    modifier applicability search means that commits the modifier chord and sends modifier press signals corresponding to the chord'"'"'s selected modifier types to a host computer upon detection of modifiable input activity that occurs substantially between touchdown and liftoff of the modifier chord; and

    , chord liftoff detection means that reports when none of the digits originally constituting the modifier chord are touching the surface and sends modifier release signals to the host computer accordingly.

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