Photoelectric measuring system

Claim 2

In a device for photoelectrically generating electrical signals in a measuring system of the type comprising a graduation carrier, a scanning plate mounted to move relative to the graduation carrier at a defined scanning distance from the graduation carrier, an illuminating arrangement, at least one photosensor, and an evaluating unit coupled to the photosensor, the improvement comprising: at least one graduation comprising a plurality of periodic grids; means for deriving a plurality of periodic signals from the periodic grids; and means for combining the plurality of periodic signals to generate a resultant signal; each of the grids defining a selected grid characteristic so that the resultant signal is generated with a predetermined waveform to reduce sensitivity to fluctuations in scanning distance.

Claim 3

The invention of claim 1 further comprising a non-periodic graduation field associated with the periodic grids to define a reference mark.

Claim 4

The invention of claim 2 wherein the graduation defines a measuring direction and wherein the non-periodic graduation field is shiftable in the measuring direction.

Claim 5

The invention of claim 3 wherein the graduation is constructed as a phase grid.

Claim 6

The invention of claim 1 wherein the graduation is constructed as a phase grid.

Claim 7

The invention of claim 5 wherein the phase grid comprises a laminar grid.

Claim 8

The invention of claim 5 wherein the phase grid comprises an echelette grid.

Claim 9

The invention of claim 1 wherein the graduation comprises first and second additional graduations, each defining a respective plurality of periodic grids, corresponding periodic grids of the first and second additional graduations having identical grid constants, individual periodic grids of a single additional graduation having differing grid constants; corresponding periodic grids in the first and second additional graduations being spaced from one another in a measuring direction defined by the measuring graduation by a fraction of multiple of the respective grid constant.

Claim 10

The invention of claim 1 wherein the illuminating arrangement and the photodetector are interchangeable with one another.

Claim 11

The invention of claim 1 wherein the illuminating arrangement comprises a plurality of light sources, each having a different wavelength distribution.

Claim 12

The invention of claim 1 wherein the combining means operates to sum the plurality of periodic signals optically.

Claim 13

The invention of claim 1 wherein the combining means operates to sum the plurality of periodic signals electronically.

Claim 14

The invention of claim 1 wherein the grid characteristics are defined in correspondence to selected terms of a predefined mathematical series.

Claim 15

The invention of claim 13 wherein the mathematical series is a Fourier series.

Claim 16

The invention of claim 1 wherein the grid characteristic represents the grid constant.

Claim 17

In a device for photoelectrically generating signals in a measuring system of the type comprising a graduation carrier, scanning plate mounted to move relative to the graduation carrier, and an illuminating arrangement, the improvement comprising: at least one graduation field located on at least one of (1) the graduation carrier and (2) the scanning plate, the graduation field comprising a plurality of grids with periodic graduation and defining a measuring direction; the graduation field, scanning plate and illuminating arrangement operative to produce a plurality of modulated signals; and means for combining the modulated signals to produce a resultant signal containing information indicative of the position of the scanning plate in the measuring direction relative to the graduation carrier; each grid constructed to define a selected grid constant in correspondence to a selected Fourier series to enhance the information contained in the resultant signal.

Claim 18

In a device for photoelectrically generating signals in a measuring system of the type comprising a graduation carrier, scanning plate mounted to move relative to the graduation carrier, and an illuminating arrangement, the improvement comprising: at least one graduation field located on at least one of (1) the graduation carrier and (2) the scanning plate, the graduation field comprising a plurality of grids with periodic graduation and defining a measuring direction; the graduation field, scanning plate and illuminating arrangement operative to produce a plurality of modulated signals; and means for combining the modulated signals to produce a resultant signal containing information indicative of the position of the scanning plate in the measuring direction relative to the graduation carrier; each grid constructed to define a selected grid constant in correspondence to a selected Fourier series to enhance the information contained in the resultant signal.