DIGIT A L ENCODING TRANSDUCERS
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DIGITAL ENCODING
TRANSDUCERS
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CHARACTERISTICS Give output in Digital format
Converts Linear or Rotary Motion into digital
format
Known as digital Encoders ,linear digitisers Shaft encoders or shaft digitisers
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CLASSIFICATION achometer ransducer
Single !utput Signal
Motion is only in one direction
"sed only for Measurement of Speed #ncremental ransducer
hree !utput Signal
hird Signal provided for $ero reference
Loss of power can cause information loss %&solute ransducer
Limited to measurement of single revolution
Loss of power does not cause information loss
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CONSTRUCTION CONTACTING
TYPE 'rushes are placed
as sliding contact
Sliding contacts
which come in
contact with
conducting area are
completed
Sliding contact which
come in contact with
insulating area are
not completed
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ADVANTAGES #t is relatively ine(pensive
%ny degree of desired accuracy
)uite ade*uate for slow moving systems
+ear of contactors and maintenance
%m&iguity of LS' digit
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MOIRE FRING METHOD !ptical method of
amplifying
displacement and
uses two identicalgratings
Gratings consist of
num&er of slits on
an opa*ue screen he slits are
transparent
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WORKING Moving the grating
perpendicular to
reference grating
would move the
fringes Movement of
fringes ,um&er of
fringes passing a point
can &e calculated %ccuracy of -./010023
over large scale
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SHAFT ENCODERS Measurement of
angular position
Disc is divided into
concentric circles %lternate segment
of opa*ue or
transparent
%ccuracy depends
of num&er of
trac4s
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CONSTRUCTIONSector Contact 1 Contact 2 Contact An!"e
0 off off off 05 to 675
2 off off ! 675 to 805
9 off ! ! 805 to2:75
: off ! off 2:75 to2;05
6 ! ! off 2;05 to9975
7 ! ! ! 9975 to9<05
= ! off !9<05 to:275
< ! off off :275 to:=05
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INCREMENTAL >rovides pulse
each time the
shaft rotates
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A#SOLUTE