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No. 99MBC095A
3. DISPLAYS AND KEY OPERATIONS
3. Changing the SHL
• With the reference workpiece set up on the Measuring Unit, connect the oscilloscope
to the [SCAN SIG.] terminal on the rear panel of the Display Unit and observe the
signal.
• SHL is the signal level for detecting a workpiece. Changing the level from the
standard level of 50% to a level such as 75% will enable the measurement of a
transparent sheet. The measurement accuracy, however, will be degraded since
measured data fluctuates according to the edge conditions of the sheet.
• It is possible to set the SHL level between 5% to 95% for "7 SHL" by setting up
"7 ADD"="USE" and "7 DLC"="OFF" in the expanded basic setup.
NOTE Measuring accuracy differs from that of the standard set up.
• Measured data differs with the change of the SHL. Perform calibration again if the
SHL setting has been changed.
• Measurement error can be reduced by performing calibration with the reference
standard, the edges of which have been made in the same condition as those of the
sheet to be measured.
Transparent Workpiece
Laser scan direction
Standard SHL (50%)
v1: Peak voltage of photo-electric signal
v2: Larger voltage of the two at edges
(as generated at the edge with
better transmittance)
New SHL: Set to 50 (1+v2/v1)%
v 1
v 2
Photo-electric signal
IMPORTANT • When the SHL (signal level for detecting a workpiece) is modified, the measure-
ment accuracy will be inevitably reduced, since the measured data may easily
fluctuate with the edge conditions.
• Once the SHL (signal level for detecting a workpiece) has been modified, always
perform another calibration.
• If an identical edge form is selected for both for the calibration standard and
workpiece (sheet), it may be possible to reduce these measurement errors.
