Renishaw Plc

Rls Merilna Tehnika D.o.o.

Gregor Dolsak

Aljaz Ogrin

Peter Kogej

Janez Novak

Blaz Hajdinjak

Matjaz Janezic

Blaz Smid

A readhead is provided for reading an absolute scale, optionally a passive magnetic scale, that encodes a series of data bits. The readhead includes a plurality of sensors, such as an array of Hall sensors, for producing a plurality of sensor signals. A plurality of signal combiners are also provided to receive at least two of the sensor signals and produce therefrom a combined sensor signal. A plurality of data bit extractors are arranged to receive at least two combined sensor signals and to determine the value of a data bit encoded in an associated absolute scale. The readhead also comprises an incremental signal generator for generating at least one incremental signal from the combined sensor signals produced by a plurality of the signal combiners. In this manner, both absolute and incremental position is measured.

Encoder readhead

A magnetic encoder apparatus is presented that includes a plurality of magnetic sensor elements (e.g. Hall sensors) for reading an associated magnetic scale that produces a periodically repeating magnetic pattern. The plurality of magnetic sensor elements produce a plurality of sensor signals and an analyzer is provided for analyzing the plurality of sensor signals to provide a measure of the position of the magnetic sensor elements relative to the associated magnetic scale. The analyzer is arranged to use the plurality of sensor signals to assess the period of the periodically repeating magnetic pattern sensed by the plurality of magnetic sensor elements. In this manner, the requirement to carefully match the period of the sensor elements with the periodically repeating magnetic pattern of the associated magnetic scale is avoided.

Magnetic encoder apparatus having a plurality of magnetic sensor elements

A scanning device for a position encoder is provided that comprises a plurality of sensor elements for generating a plurality of sensor signals. A summation unit is also provided for generating at least a first summation signal and a second summation signal that provide information on the relative alignment of the scanning device and an associated scale. The first summation signal is generated from a first subset of the plurality of sensor signals and the second summation signal is generated from a second subset of the plurality of sensor signals. The plurality of sensor elements are substantially evenly spaced apart from one another N and sensor elements are provided per period of an associated scale, wherein N is an integer value and a multiple of three and four. In this manner, the third harmonic contribution to the summation signals is suppressed.

Position encoder apparatus

A magnetic scale includes a scale member having a plurality of grooves. The scale member defines a passive magnetic scale track. The plurality of grooves include grooves of at least a first groove type and a second groove type, the magnetic properties of the scale member in the locality of grooves of the first groove type being different than the magnetic properties of the scale member in the locality of grooves of the second groove type. The scale member is arranged to carry or encode absolute position information in the form of at least one codeword comprising a sequence of data bits, wherein each of the data bits is provided by a groove of the scale member, the data bit taking a first value if the groove is of the first groove type and a second value if the groove is of the second groove type.

Magnetic encoder apparatus

A scale () has magnetic incremental scale marks in a track (), and a pseudo-random code sequence in a reference mark track (). Sensors () feed the pattern of the code in the track () into a bi-directional shift register (). So that a user can select any desired position for use as a reference mark, a memory () is provided, into which any selected code value can be pre-stored. A comparator () then compares the code value in the shift register () with the code value in the memory () and outputs a reference mark signal (Ri) when they match.

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Velike Lasce, Slovenia

Gregor Dolsak