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US 4,064,504 AGranted
Digital coding of angles
AssigneeSociete d'Etudes, Recherches et Constructions Electroniques Sercel
InventorsMarc Lepetit, Philippe Angelle, Jacques Bodin, Dominique DU Boisbaudry
Life of this patent
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Abstract
In a digital angle coder, a revolving disc bears a first series of marks ularly spaced around its axis, capable of being read by two diametrically-opposed fixed heads, and a second series of marks equal in number to the first, regularly spaced around the axis and capable of being read by two diametrically opposed movable heads. Each of the heads includes, for example, a grid reproducing a portion of the series of marks, a photo-emission element and a photo-receiving element. A first auxiliary mark may be read by a fixed auxiliary head and a second auxiliary mark may be read by a movable auxiliary head.
Claims13
In a digital angle coder comprising:
- first and second angle defining members which are relatively rotatable about a first axis of rotation and the angular shift of which is to be detected,
- an auxiliary revolving member driven in continuous rotation at a substantially constant speed about a second axis of rotation substantially coinciding with said first axis of rotation,
- a coding means and code-reading means arranged for cooperation between said angle defining members and said auxiliary rotating member, one of said coding and code-reading means being arranged on said auxiliary revolving member and the other of said coding and code reading means being arranged on each of said angle defining members, said coding means comprising at least one plurality of fine markings regularly spaced about the axis of rotation of the member carrying said coding means and at least one coarse marking, and said code-reading means is adapted to read said fine markings to provide repetitively first and second read fine marking signals relating to said first and second angle defining members, respectively, and is adapted to read said at least one coarse marking during each rotation of the member carrying the coding means to provide coarse marking signals,
- fine angle detection means including means for producing time-shift signals corresponding to the time-shifts between each of the first read fine marking signals and the associated one of the second read fine marking signals,
- means for deriving from said time-shift signals a fine value signal representative of the angle between said first and second angle defining members,
- coarse angle detection means responsive to successive coarse marking signals for producing a coarse value signal representative of the angle between said first and second angle defining members, and
- means for combining said fine value and coarse value signals into a digitally coded representation of the angle between said first and second angle defining members,
- the improvement of said means for deriving a fine value signal including means for averaging the time-shifts represented by said time-shift signals over one or more complete revolutions of said auxiliary revolving member, whereby the angle measurement is rendered very accurate by compensation of inequalities in the angular spacing of the markings.
5 more elements
In a digital angle coder comprising:
- first and second angle defining members which are relatively rotatable about a first axis of rotation and the angular shift of which is to be detected,
- an auxiliary revolving member driven in continuous rotation at a substantially constant speed about a second axis of rotation substantially coinciding with said first axis of rotation,
- coding means arranged on said auxiliary revolving member and comprising at least one plurality of fine markings, regularly spaced about the axis of rotation thereof, and at least one coarse marking,
- code reading means arranged on each of said first and second angle defining members and adapted to read said fine markings to provide repetitively first and second read fine marking signals relating to said first and second angle defining members, respectively, and is adapted to read said at least on coarse marking during each rotation of the member carrying the coding means to provide coarse marking signals,
- fine angle detection means including means for producing time-shift signals corresponding to the time shifts between the first read fine marking signals and the associated second read fine marking signals,
- means for deriving from said time-shift signals a fine value signal representative of the angle between said first and second angle defining members,
- coarse angle detection means responsive to successive coarse marking signals for producing a coarse value signal representative of the angle between said first and second angle defining members, and
- means for combining said fine value and coarse value signals into a digitally coded representation of the angle between said first and second angle defining members,
- the improvement of said means for deriving a fine value signal including means for averaging the time-shifts represented by said time-shift signals over one or more complete revolutions of said auxiliary revolving means, whereby the angle measurement is rendered very accurate by compensation of inequalities in the angular spacing of the markings.
6 more elements
Dependencies are inferred from the claim text.