3 - 11
No. 99MBC032A
3. DISPLAYS AND KEY OPERATIONS
b) Plate (Sheet)
• If the workpiece being measured is a transparent plate (sheet) with edges that are not
chamfered or beveled, there may not be a sharp contrast in the amount of light at the
transition from the highlighted portion to the shaded portion. As a result, the voltage
generated by the incident light on the photo-electric element can not reach the threshold
voltage level (SHL), and Segment 2 is determined to not exist (Err-0).
Workpiece
Laser scan direction
Ideal edge signal
Binary voltage level (SHL)
Photo-electric signal
Measurement is aborted
because a sharp edge
can not be determined.
• For measuring a transparent plate-shaped workpiece
Take the following precautions:
1. Incline the workpiece.
By inclining the workpiece it is possible to attain a sharp edge from the light con-
trast. In this case:
Measurement : W = W0 (workpiece dimension) x cos θ
W
0
W
θ
Workpiece
Direction of light is turned, and is not incidental to the photo-electric element.
2. Chamfering
Chamfer the workpiece edge by W. Be sure that W will be larger than 0.4 mm.
W
Workpiece
Direction of light is turned,
and is not incidental to the
photo-electric element.
