Page 93 - Sensors and Control Systems in Manufacturing

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T w o
Cha p te r

FIGURE 2.14 Box counting with FIGURE 2.15 Detecting proper cookie
photoelectric sensor. arrangement.

module detects light or dark that lasts too long, and the output device
shuts the oven down.
Placing the photoelectric sensor to detect a saw tooth (Fig. 2.16)
enables the programmable controller to receive an input signal that
rotates the blade into position for sharpening of the next tooth.
A through-beam photoelectric sensor is used to time the toll gate
in Fig. 2.17. To eliminate toll cheating, the gate lowers the instant the
rear of the paid car passes the control. The rugged sensor can handle
harsh weather, abuse, and 24-hour operation.
A safe and secure garage is achieved through the use of a through-
beam photoelectric sensor interfaced to the door controller. The door
shuts automatically after a car leaves, and if the beam is broken while
the door is lowering, the motor reverses direction and raises the door
again (Fig. 2.18).

FIGURE 2.17 Toll-booth
FIGURE 2.16 Sawtooth control with photoelectrical
inspection. sensor.