Built-In Reference Point (R/Rs); Reference Point Detection; Reference Point Mask; Speed Variation During Reference Point Detection - Sony BS78 Series Instruction Manual

3-6. Built-in Reference Point (R/RS)

3-6-1. Reference Point Detection

A mono-directional reference point is used as the built-in optical reference point for the Laserscale unit. As
a result, reference point detection should be performed using the relative traveling directions of the scale and
detector head shown in the diagram below. The reference point signal will rise during detection.
(Performing reference point detection in the reverse direction will lower the reference point accuracy.)

3-6-2. Reference Point Mask

Reference points can be detected using a deceleration dog or by masking unnecessary reference points with
the supplied reference point masking labels. If masking the reference point, affix a mask label using the
procedure shown in Fig. 3-23.
Affixing procedure
1. Wash the scale with alcohol.
2. Use a set of tweezers to peel off the
supplied reference point mask label from
the board.
3. Affix the label from the side having the
model number label so as to cover the
unneeded reference point pattern.
n
When affixing the label, be careful not to
touch the scale surface and leave any
fingerprints or other marks.

3-6-3. Speed Variation During Reference Point Detection

To attain the designated accuracy (± 0.1 µm), speed should be kept constant during reference point detec-
tion. Any speed variation should be limited to less than 0.2 mm/s. The maximum detection speed is 100 mm/
s.
16
(E)
Standard specifications
Scale
Detector head
Fig. 3-22
Fig. 3-23
Reference point signal
Reference point mask label
Scale
BS78