Page 160 - Sensors and Control Systems in Manufacturing

Classification and Types of Sensors

FIGURE 2.116 Detection of double-fed or mispositioned resistors. 121

• Detection of double-fed or mispositioned resistors prior to taping.
Through-beam-type sensor heads are positioned above and
below the resistors traveling on a transfer line. A variation on
the line changes the quantity of light in the laser beam, thus
signaling a defect (Fig. 2.116).
• Detection of defective shrink wrapping of videocassette. Defective
film may wrap or tear during shrink wrapping. The laser sen-
sor detects defective wrapping by detecting a change in the
light quantity on the surface of the videocassette (Fig. 2.117).
• Measurement of gap between roller and doctor blade. Measures
the gap between the roller and the doctor blade in submi-
crometer units. The sensor’s automatic measurement opera-
tion eliminates reading errors (Fig. 2.118).
• Measurement of surface run-out of laser disk. The surface
run-out of a laser disk is measured at a precision of 0.5 μm.
The sensor head enables measurement on a mirror-surface
object (Fig. 2.119).

FIGURE 2.117 Detection of defective shrink wrapping of videocassette.