Photoelectric measuring system
First Claim
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1. 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.
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Abstract
In a photoelectric measuring arrangement two grids operating as a scale and a scanning plate are built up of several component phase grids which define periodic graduations having differing grid constants. The periodic signals of differing periodicity arising through diffraction are optically or electrically summed.
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Citations
16 Claims
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1. 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:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. 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:
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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.
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Specification