Determination of a position code

US6548768B1 · kind B1 · utility

Assignee

• Anoto AB · SE

Inventors

• Mats Petter Pettersson · Lund, SE
• Tomas Edso · Lund, SE

Key dates

• Filing date: Oct 2, 2000
• Grant date: Apr 15, 2003
• Expiry date: Aug 22, 2021

Classification

• Technology area (CPC G): Physics
• CPC primary: G06V10/19
• WIPO field: Computer technology
• WIPO sector: Electrical engineering

Abstract

A method and a device for determining a virtual raster of a code pattern consisting of a plurality of marks with associated coordinates mn. Each mark is located at a nominal position but displaced from the nominal position in one of a plurality of directions, depending upon the value of the mark. The nominal positions form raster points gn of the virtual raster, and the raster points are situated on raster lines, which intersect at a first angle. In addition there is a device for determining an initial vector V1,2 on the basis of the coordinates m1, m2 of one or more marks, which initial vector extends approximately between a first and a second adjacent raster point g1, g2. A calculation device determines a second vector V2,3, which forms said angle with the first vector and is the same length as the first vector and extends from the second raster point g2 approximately to a third raster point g3. The mark coordinate m3 which is associated with the third raster point g3 is determined. Subsequently the actual coordinates are calculated for the third raster point on the basis of the third mark's coordinates and its value. The actual coordinates for the third raster point are stored, …