Encoder

• US 20040118998A1
• Filed: 08/01/2003
• Published: 06/24/2004
• Est. Priority Date: 12/19/2002
• Status: Active Grant

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Nokia Corporation
• Inventors: Fermawi, Maysara, Wingett, Gary, Bick, Andrew Raymond
• Granted Patent: US 7,183,536 B2
• Time in Patent Office: Days
• US Class Current: 250/231.13
• CPC Class Codes: G01D 5/363 Direction discrimination

Abstract

A motion encoder for use with a rotating key. The motion encoder allows the direction of rotation to be determined by providing elements having different characteristics for the transmission of a IR beam. These elements are arranged in a pattern that allows an IR beam impinging on the elements to trace a path detected as the rotating key turns. The beam being detected after changes in the reflected or transmitted beam indicating the direction of rotation of the beam.

Claims

1. A motion encoder for determining rotational movement of a rotatable member comprising

An element providing areas having respectively different characteristics for the onward transmission of electromagnetic radiation, the areas being arranged to provide a directionally unique sequence of transmission characteristics along a path traced on rotation of the rotatable element.

2. A motion encoder according to claim 1 further comprising a source of electromagnetic radiation and a detector for sensing the onward transmission of the electromagnetic radiation.

3. A motion encoder according to claim 1 wherein the detector is located for rotation with the rotatable member.

4. A motion encoder according to claim 1 wherein the source is located for rotation with the rotatable member

5. A motion encoder according to claim 1 wherein the characteristics are reflection characteristics.

6. A motion encoder according to claim 1 wherein there are areas having three different characteristics that are repeated in the same order on the surface along the path of the trace.

7. A motion encoder according to claim 1 wherein the rotatable member allows movement in an axis perpendicular to the plane of the rotatable member.