Absolute capacitive rotary encoder

Patent metadata

Field	Value
Publication number	US-2016161291-A1
Application number	US-201514958836-A
Country	US
Kind code	A1
Filing date	Dec 3, 2015
Priority date	Dec 4, 2014
Publication date	Jun 9, 2016
Grant date	—

Abstract

Some embodiments of the invention include an absolute capacitive rotary encoder comprising a first disk, which is rotatable relative a second disk, and a first sensor ring and a second sensor ring. The first and the second sensor ring each have a multiplicity of first coupling electrodes and second coupling electrodes capacitively coupling to one another. The first coupling electrodes of a respective sensor ring have different coupling signal phases. The first sensor ring and the second sensor ring are matched to one another in such a way that an angle is determinable absolutely.

First claim

1 - 16 . (canceled)

17 . An absolute capacitive rotary encoder, comprising:
a first sensor ring and at least one second sensor ring, each comprising:
a multiplicity of first coupling electrodes arranged in a circular shape on a first disk and aligned radially; and
a multiplicity of second coupling electrodes arranged in a circular shape on a second disk and aligned radially, wherein:
the circular widths of the first and second coupling electrodes of a respective sensor ring are matched to one another,
the first disk and the second disk are arranged coaxially on a measuring axis and at a distance from one another,
the first disk and the second disk are rotatable relative to one another about the measuring axis, wherein the distance between the first disk and the second disk is dimensioned in such a way that time-varying coupling signals are transmittable between the first and second coupling electrodes of a respective sensor ring by way of capacitive coupling, and

an absolute angle is determinable by evaluating the coupling signals of both sensor rings transmitted between the first and second coupling electrodes,
the first coupling electrodes of a respective sensor ring have at least three mutually offset coupling signal phases, wherein
respectively one alpha-interval is defined on the basis of the number of coupling signal phases,
a structure of the first coupling electrodes is predetermined by the alpha-intervals,
each sensor ring has an alpha-interval overall number as the total of all alpha-intervals of the respective sensor ring and
the first alpha-interval overall number of the first sensor ring and the second alpha-interval overall number of the second sensor ring are co-prime for determining an absolute angle,
the sequence of the first coupling electrodes of the first sensor ring is defined by a first phase permutation and the sequence of the first coupling electrodes of the second sensor ring is defined by a second phase permutation such that,
by means of the first phase permutation, respectively a row of circularly adjacent first coupling electrodes of the first sensor ring forms a first P-interval which corresponds to a first number of alpha-intervals, and
by means of the second phase permutation, respectively a row of circularly adjacent first coupling electrodes of the second sensor ring forms a second P-interval which corresponds to a second number of alpha-intervals,
the first sensor ring has a number of equal first P-intervals and the second sensor ring has a number of equal second P-intervals, and
the second coupling electrodes are divided into at least two mutually alternate types for a differential signal evaluation of coupling signals, wherein, in the case of two types, second coupling electrodes on each sensor ring spaced apart by one in the circular direction are of the same type in each case.

18 . The rotary encoder according to claim 17 , wherein:
the second disk comprises a rotor disk.

19 . The rotary encoder according to claim 17 , wherein:
the first disk comprises a stator disk.

20 . The rotary encoder according to claim 17 , wherein:
the first coupling electrodes comprise emitter electrodes.

21 . The rotary encoder according to claim 17 , wherein:
the second coupling electrodes comprise receiver electrodes.

22 . The rotary encoder according to claim 17 , wherein:
the three mutually offset coupling signal phases comprise four coupling signal phases respectively offset by a quarter.

23 . The rotary encoder according to claim 17 , wherein:
in the case of at least one sensor ring, the coupling signals of the second coupling electrodes per type of a sector are brought together sector-by-sector, wherein:
the sectors are distributed over the whole sensor ring and
the number of sectors is at least three,
such that information about a deviation of the arrangement of the first and/or second disk from an ideal location relative to the measuring axis is establishable by a sector-related comparing evaluation of coupling signals, wherein the number of second coupling electrodes per type is a mathematical multiple of the number of sectors.

24 . An absolute capacitive rotary encoder, comprising:
a first sensor ring and at least one second sensor ring, each comprising:
first coupling electrodes arranged in a circular shape on a first disk and aligned radially, and
second coupling electrodes arranged in a circular shape on a second disk and aligned radially,
wherein: the circular width of the first and second coupling electrodes of a respective sensor ring are matched to one another, the first disk and the second disk are
arranged coaxially on a measuring axis and at a distance from one another and rotatable relative to one another about the measuring axis, wherein
the distance between the first disk and the second disk is dimensioned in such a way that time-varying coupling signals are transmittable between the first and second coupling electrodes of a respective sensor ring by way of capacitive coupling, and
an absolute angle is determinable by evaluating the coupling signals of both sensor rings transmitted between the first and second coupling electrodes,
the first coupling electrodes have at least three mutually offset coupling signal phases, wherein
respectively one alpha-interval is defined on the basis of the number of coupling signal phases,
a structure of the first coupling electrodes is predetermined by the alpha-intervals,
each sensor ring has an alpha-interval overall number as the total of all alpha-intervals of the respective sensor ring,
the second coupling electrodes are divided into at least two mutually alternate types for a differential signal evaluation, wherein second coupling electrodes, respectively spaced apart by one in the circular direction, of each sensor ring are of the same type, and, in the case of at least one sensor ring, the coupling signals of the second coupling electrodes of a type of a sector are brought together sector-by-sector, wherein
the sectors are distributed over the whole sensor ring and
the number of sectors is at least three,
such that information about a deviation of the arrangement of the first and/or second disk from an ideal location relative to the measuring axis is establishable by a sector-related comparing evaluation of coupling signals from different sectors, wherein the number of second coupling electrodes is a mathematical multiple of the number of sectors.

25 . The rotary encoder according to claim 24 , wherein:
by means of the information about a deviation of the arrangement of the first and/or second disk from an ideal location relative to the measuring axis, low frequency errors which are caused by a deviation of the arrangement of the first and/or second disk from an ideal location relative to the measuring axis, are compensatable and/or the deviation of the arrangement of the first and/or second disk from an ideal location relative to the measuring axis is determinable.

26 . The rotary encoder according to claim 24 , wherein:
the coupling signals of the second coupling electrodes of the same type are combined sector-by-sector, respectively both in the first sensor ring and in the second sensor ring, wherein
the number of sectors of the first sensor ring differs from the number of sectors of the second sensor ring and/or
the sectors of the first sensor ring are arranged offset to the sectors of the second sensor ring,
and/or the coupling signals are combined sector-by-sector by virtue of the second coupling electrodes of the same type of a respective sector being connected in an electrically conductive manner on the second disk.

Assignees

• Hexagon Technology Ct Gmbh

Inventors

• Rohner Marcel
• Bednarek Ingo
• Baumann Lukas
• Wohlgenannt Rainer

Classifications

• G01D5/24 Primary

  by varying capacitance · CPC title

• G01D5/2415 Primary

  adapted for encoders · CPC title