HS50_advance_level 2.pdf - 第144页
07/2002 Editio n Student G uide HS -50 Advanc ed II 6 Cont rol & C ommun icatio n 14 'LJL WL]DWLR QRI7 UDFN6LJQDOV Digitiza tion an d multipl ication of the an alogue track signals . The electr onic m…
Student Guide HS-50 Advanced II 07/2002 Edition
6 Control & Communication
13
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As described on the previous page the encoder produces 2 track signals (A and B) that
are phase shifted by 90 degrees. Here we see Track A leading Track B indicating the
axis is moving to the right.
Track scale
Encoder with scale for track A and B
Track A and B measure the same
scale but the encoder scale is shifted
by the half of bright or dark distance.
This makes a 90 degree signal shift.
If the encoder moves to the right track
signal A is the leading signal before
track signal B. If the encoder moves to
the left the reverse happens.
07/2002 Edition Student Guide HS-50 Advanced II
6 Control & Communication
14
'LJLWL]DWLRQRI7UDFN6LJQDOV
Digitization and multiplication of the analogue track signals.
The electronic multiplication of the track signals is based on the voltage level and on the phase
shift of the two track signals (the drawing is simplified). There is a Schmitt Trigger circuit with
phase check and this digitizes and multiplies the analogue track signals. These pulses have a fre-
quency of 25 times that of the analogue waveform with each pulse formed as the analogue wave-
form passes certain predetermined voltage levels.
5,12 ms
0,512 ms
Student Guide HS-50 Advanced II 07/2002 Edition
6 Control & Communication
15
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Phase shift check on possible count errors.
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5,12 cm
The tolerance at the analogue signal of the track signal is checked according the limit of
90° +/- 15°
90° +/- 15°.