Position measuring system
First Claim
1. In a position measuring system for measuring the relative position of two objects, of the type comprising a graduation carrier which defines a graduation extending along a measuring direction and a scanning unit which scans the graduation and generates at least one periodic analog signal having a bandwidth N, the improvement comprising:
- at least two first scanning fields included in the scanning unit, offset with respect to one another along the measuring direction, each first scanning field comprising N first partial fields, adjacent first partial fields displaced with respect to one another by a constant dimension in the measuring direction, each of the first partial fields defining a respective width along the measuring direction, said widths of the first partial fields varying according to a selected sine function; and
means for developing a plurality of first periodic signals, each from a respective one of the first partial fields, and for superposing the first periodic signals to generate at least one composite periodic signal, said selected sine function chosen such that the composite signal is harmonic-free.
1 Assignment
0 Petitions
Accused Products
Abstract
In a position measuring system for measuring the relative position of two objects, a scale having a graduation with a graduation period P is scanned by a scanning unit in order to generate a periodic analog signal having a bandwidth N. In order to generate harmonic-free Fourier coefficients of the fundamental wave of the periodic analog signal, a scanning plate included in the scanning unit includes a first scanning group with first and second scanning fields as well as a second scanning group with first and second scanning fields. The first scanning group is offset with respect to the second scanning group by P/4. The first scanning fields are offset with respect to the second scanning fields by P/2. Each scanning field includes N partial fields which are offset with respect to one another by P/2N in the measuring direction. The widths of the partial fields are varied in the measuring direction according to a sine function. To each scanning field there is allocated a scanning element, and the scanning elements of the second scanning fields are connected in difference of those of the first scanning fields. The scanning elements are connected to an evaluating arrangement for the formation of position measuring values.
36 Citations
12 Claims
-
1. In a position measuring system for measuring the relative position of two objects, of the type comprising a graduation carrier which defines a graduation extending along a measuring direction and a scanning unit which scans the graduation and generates at least one periodic analog signal having a bandwidth N, the improvement comprising:
-
at least two first scanning fields included in the scanning unit, offset with respect to one another along the measuring direction, each first scanning field comprising N first partial fields, adjacent first partial fields displaced with respect to one another by a constant dimension in the measuring direction, each of the first partial fields defining a respective width along the measuring direction, said widths of the first partial fields varying according to a selected sine function; and means for developing a plurality of first periodic signals, each from a respective one of the first partial fields, and for superposing the first periodic signals to generate at least one composite periodic signal, said selected sine function chosen such that the composite signal is harmonic-free. - View Dependent Claims (2, 3, 4, 5)
-
-
6. In a position measuring system for measuring the relative position of two objects, of the type comprising a graduation carrier which defines a graduation extending along a measuring direction and a scanning unit which scans the graduation and generates at least one periodic analog signal having a bandwidth N, the improvement comprising:
-
at least two first scanning fields included in the scanning unit, each defining a respective first scanning field midline, said first scanning field midlines being offset with respect to one another along the measuring direction, each first scanning field comprising M first partial fields, where M≧
N, each first partial field defining a respective first partial field midline, said first partial fields positioned such that the separation in the measuring direction between the first partial field midlines and the respective first scanning field midline varies according to a selected arc-sine function, each of said first partial fields defining a constant width; andmeans for developing a plurality of first periodic signals, each from a respective one of the first partial fields, and for superposing the first periodic signals to generate at least one composite periodic signal, said selected arc-sine function chosen such that the composite signal is harmonic-free. - View Dependent Claims (7, 8, 9, 10, 11, 12)
-
Specification