singleturn encoders Multiturn encoders the absolute position information repeats itself with every revolution. can also distinguish between revolutions. Circular graduations of absolute rotary encodersWith the absolute measuring method, the position value is available from the encoder immediately upon switch-on and can be called at any time by the subsequent electronics. There is no need to move the axes to fi nd the reference position. The absolute position information is read from the grating on the graduated disk, which is designed as a serial code structure or— as on the ECN 100—consists of several parallel graduation tracks. A separate incremental track (on the ECN 100 the track with the fi nest grating period) is interpolated for the position value and at the same time is used to generate an optional incremental signal.In The absolute position established by the reference mark is gated with exactly one measuring step.The reference mark must therefore be scanned to establish an absolute reference or to fi nd the last selected datum. Circular graduations of incremental rotary encoders

Measuring Principles Measuring StandardMeasurement Methods

incremental measuring method, reference mark. the graduation consists of a periodic grating structure. The position information is obtained by counting the individual increments (measuring steps) from some point of origin. Since an absolute reference is required to ascertain positions, the graduated disks are provided with an additional track that bears a HEIDENHAIN encoders with optical scanning incorporate measuring standards of periodic structures known as graduations. These graduations are applied to a carrier substrate of glass or steel.These precision graduations are manufactured in various photolithographic processes. Graduations are fabricated from:extremely hard chromium lines on glass, matte-etched lines on gold-plated steel tape, orthree-dimensional structures on glass or steel substrates.The photolithographic manufacturing processes developed by HEIDENHAIN produce grating periods of typically 50 µm to 4 µm.These processes permit very fi ne grating periods and are characterized by a high defi nition and homogeneity of the line edges. Together with the photoelectric scanning method, this high edge defi nition is a precondition for the high quality of the output signals. The master graduations are manufactured by HEIDENHAIN on custom-built high- precision ruling machines. ••• With the

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