Indicating positions
First Claim
1. Apparatus for indicating the relative positions in a given direction between a reference point and a test point spaced therefrom and movable relative thereto, comprisingreference surface means movable in response to movement of the reference point, and having at least a relevant reference portion that is covered with a plurality of substantially equally spaced lines thereon predominantly in a direction normal to the given direction,test surface means movable in response to movement of the test point, and having at least a relevant test portion that is substantially similar and parallel to the relevant reference portion of the reference surface means, and covered with a plurality of substantially equally spaced lines thereon predominantly in a direction normal to the given direction,the relevant portion of each surface means being adjacent and overlapping the relevant portion of the other surface means throughout a useful range of relative positions, and at least one relevant portion being substantially transparent between the lines thereon, andmeans for illuminating the relevant portions to form moire fringes,the reference surface means and test surface means being so arranged that relative movement between the test point and the reference point having a component in the given direction varies the angle between the lines on the relevant portions of the respective surface means and thus causes the spacing of the moire fringes formed by the lines to vary as a function of the relative positions between the reference point and the test point in the given direction.
1 Assignment
0 Petitions
Accused Products
Abstract
Typical apparatus as shown in FIGS. 1 and 12 for indicating the relative positions in a given direction between a reference point (24,59) and a test point (29,68) spaced therefrom and movable relative thereto is useful for measurement of the magnitude and direction of static or dynamic torque in a shaft (8). Overlapping transparent reference (20,60) and test surfaces (25,61), either parallel disks (60,61) or coaxial cylinders (20,25) each having a relevant portion covered with a plurality of equally spaced lines oriented predominantly normal to the given direction and at an angle to each other, produce moire fringes (30) when illuminated (14,15). One of the surfaces (25,61), being flexible, is connected to the shaft (8) so as to flex in response to torque between the reference point (24,59) and the test point (29,68), causing a change in the angle between the lines on the two surfaces (20,25;60,61), and thus of the spacing (D) (FIG. 3) of the moire fringe bands (30), which is optically detected (17) and converted, as shown in FIG. 4, to an electrical signal (42) to control power applied to the shaft (8).
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Citations
36 Claims
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1. Apparatus for indicating the relative positions in a given direction between a reference point and a test point spaced therefrom and movable relative thereto, comprising
reference surface means movable in response to movement of the reference point, and having at least a relevant reference portion that is covered with a plurality of substantially equally spaced lines thereon predominantly in a direction normal to the given direction, test surface means movable in response to movement of the test point, and having at least a relevant test portion that is substantially similar and parallel to the relevant reference portion of the reference surface means, and covered with a plurality of substantially equally spaced lines thereon predominantly in a direction normal to the given direction, the relevant portion of each surface means being adjacent and overlapping the relevant portion of the other surface means throughout a useful range of relative positions, and at least one relevant portion being substantially transparent between the lines thereon, and means for illuminating the relevant portions to form moire fringes, the reference surface means and test surface means being so arranged that relative movement between the test point and the reference point having a component in the given direction varies the angle between the lines on the relevant portions of the respective surface means and thus causes the spacing of the moire fringes formed by the lines to vary as a function of the relative positions between the reference point and the test point in the given direction.
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33. Apparatus for indicating the relative angular positions between a reference point and a test point axially spaced therefrom and coaxially movable relative thereto, comprising
reference surface means fixedly connected with the reference point, and having at least a relevant reference portion that is substantially cylindrical, coaxial with the relative movement, and covered with a plurality of substantially equally spaced and predominantly axial lines thereon, test surface means fixedly connected at a reference end thereof with the reference point, fixedly connected at a test end thereof with the test point, and having at least a flexible relevant test portion that is substantially cylindrical, coaxial with the relative movement, and covered with a plurality of substantially equally spaced and predominantly axial lines thereon, the relevant portion of each surface means being adjacent and overlapping the relevant portion of the other surface means throughout a useful range of relative angular positions, and at least one relevant portion being substantially transparent between the lines thereon, and means for illuminating the relevant portions to form moire fringes, coaxial relative movement between the test point and the reference point thus varying the relative orientation between the lines on the relevant portions of the respective surface means and causing the spacing of the moire fringes formed by the lines to vary as a function of the relative angular positions between the reference point and the test point.
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36. Apparatus for indicating the relative angular positions between a reference point and a test point axially spaced therefrom and coaxially movable relative thereto, comprising
substantially rigid reference surface means fixedly connected with the reference point, and having at least a relevant reference portion that is substantially flat, normal to the axis of relative movement, and covered with a plurality of substantially equally spaced and predominantly radial lines thereon, test surface means fixedly connected at a reference end thereof with the reference point, fixedly connected at a test end thereof with the test point, and having at least a flexible relevant test portion that is substantially flat, normal to the axis of relative movement, and covered with a plurality of substantially equally spaced and predominantly radial lines thereon, the relevant portion of each surface means being adjacent and overlapping the relevant portion of the other surface means throughout a useful range of relative angular positions, and at least one relevant portion being substantially transparent between the lines thereon, and means for illuminating the relevant portions to form moire fringes, coaxial relative movement between the test point and the reference point thus varying the relative orientation between the lines on the relevant portions of the respective surface means and causing the spacing of the moire fringes formed by the lines to vary as a function of the relative angular positions between the reference point and the test point.
Specification