Multi-phase printed circuit board tachometer

• US 4,803,425 A
• Filed: 10/05/1987
• Issued: 02/07/1989
• Est. Priority Date: 10/05/1987
• Status: Expired due to Fees

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Swanberg, Melvin E.
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): Regan, Maura K.
• Application Number:
  US07/104,726
• Time in Patent Office: 491 Days
• Field of Search: 324/207, 324/173, 324/174, 324/208, 336/200, 336/220, 336/232, 310/168, 361/236, 361/240
• US Class Current: 324/173
• CPC Class Codes: G01P 13/045 with speed indication
• CPC Class Codes: G01P 3/487 delivered by rotating magnets
• CPC Class Codes: H02K 21/24 with magnets axially facing the armatures, e.g. hub-type cycle dynamos
• CPC Class Codes: H02K 3/26 consisting of printed conductors

Abstract

This invention relates to a multi-phase printed circuit board (PCB) tachometer for accurate measurement of the rotational speed and direction of an electric motor. The multi-phase output not only provides rotation velocity in the form of the conventional a-c output signal, but also provides rotation direction information, in addition to providing a higher rotational resolution than conventional PCB tachometers. According to a first embodiment of the present invention, a multi "winding", multi-phase PCB tachometer that uses a single multi-pole magnet is constructed by using double sided boards with plated through holes. In a second embodiment, a multi-phase tachometer configuration is disclosed in which the number of radial printed circuit traces and the number of pole magnets are not equal, whereby the individual voltages generated across each radial segment will not be in phase, and thus can provide rotational direction information as well as velocity information.

Claims

1. A printed circuit winding pair for use in AC tachometers comprising:

a first winding on a board substrate, said winding having a first terminal and a second terminal, a continuous conductive trace from said first terminal to said second terminal, said trace following a generally serpentine pattern, said pattern being circular in shape, such that said serpentine pattern comprises radial loops extending outwardly from a central point,

a second winding on said board substrate, said second winding having a first terminal and a second terminal, a continuous conductive trace from said first terminal to said second terminal, said trace following a generally serpentine pattern, said pattern being circular in shape, such that said serpentine patterns comprises radial loops extending outwardly from a central point,

said second winding being rotated slightly from and interwined with said first winding, wherein the outer circular parts of said first winding is formed on the reverse side of said board substrate and connected to the radial traces of said first winding by plated through holes, and wherein the inner circular parts of said secured winding is formed on the reverse side of said board substrate and connected to the radial traces of said second winding by plated through holes, such that said first and second windings are electrically isolated from each other.