{
  "patent_number": "US 6323846",
  "country": "US",
  "title": "How a Multi-Touch Screen Detects Multiple Fingers and Palms",
  "original_title": "Method and apparatus for integrating manual input",
  "summary": "This patent describes the underlying electronic circuits and methods for a multi-touch surface that can track multiple fingers and palms simultaneously, even before they fully touch the screen.",
  "what_it_does": "This patent details how a multi-touch surface detects multiple finger and palm contacts. It uses an array of individual sensing devices (Claim 7), each sensitive to changes in its own electrical field (self-capacitance) as a hand or finger gets close (Claim 1). Each sensing device includes two electrical switches, a sensing electrode, a power supply, and circuitry to measure the electrical changes (Claim 1). Control circuitry sequentially activates each sensor, converting the electrical signals into digital data that represents the position and shape of multiple touches (Claim 7). For example, this system could track both a user's thumb and index finger as they pinch or zoom on a screen, even recognizing the difference between a fingertip and a palm.",
  "what_it_does_not_cover": [
    "Does not cover touchscreens that only detect a single point of contact at a time.",
    "Does not cover resistive touchscreens, which work by two conductive layers pressing together.",
    "Does not cover optical touch systems that use cameras or light beams to detect touch.",
    "Does not cover touch devices that rely solely on surface acoustic wave (SAW) technology.",
    "Does not cover systems that lack the specific sensing device architecture described in Claim 1, including the series-connected switching means and integrating capacitor."
  ],
  "filed": "1999-01-25",
  "granted": "2001-11-27",
  "expires": null,
  "status": "active",
  "holder": "University of Delaware",
  "holder_url": "https://patentbrief.org/company/university-of-delaware",
  "inventors": [
    {
      "name": "Wayne Westerman",
      "url": "https://patentbrief.org/inventor/wayne-westerman"
    },
    {
      "name": "John G. Elias",
      "url": "https://patentbrief.org/inventor/john-g-elias"
    }
  ],
  "times_cited": 2641,
  "tags": [
    "consumer_electronics",
    "software",
    "telecommunications",
    "semiconductors"
  ],
  "abstract": "Apparatus and methods are disclosed for simultaneously tracking multiple finger and palm contacts as hands approach, touch, and slide across a proximity-sensing, compliant, and flexible multi-touch surface. The surface consists of compressible cushion, dielectric, electrode, and circuitry layers. A simple proximity transduction circuit is placed under each electrode to maximize signal-to-noise ratio and to reduce wiring complexity. Such distributed transduction circuitry is economical for large surfaces when implemented with thin-film transistor techniques. Scanning and signal offset removal on an electrode array produces low-noise proximity images. Segmentation processing of each proximity image constructs a group of electrodes corresponding to each distinguishable contact and extracts shape, position and surface proximity features for each group. Groups in successive images which correspond to the same hand contact are linked by a persistent path tracker which also detects individual contact touchdown and liftoff. Combinatorial optimization modules associate each contact's path with a particular fingertip, thumb, or palm of either hand on the basis of biomechanical constraints and contact features. Classification of intuitive hand configurations and motions enables unprecedented integration of typing, resting, pointing, scrolling, 3D manipulation, and handwriting into a versatile, ergonomic computer input device.",
  "url": "https://patentbrief.org/patent/us/6323846/aqua-user-interface",
  "markdown_url": "https://patentbrief.org/patent/us/6323846/aqua-user-interface/md",
  "google_patents_url": "https://patents.google.com/patent/US6323846",
  "relatedPatents": []
}