2. Electro-pneumatic Combination of electrical and
pneumatic system
Used when the process is repeating and setup cost is
low
But
◦ Maintenance – troubleshooting is very complex
◦ Structure – circuit structure is messy when
involving complex design
8. • Sensors that are able to detect the presence of nearby objects
without any physical contact.
•A proximity sensor often emits:
1) Electromagnetic or electrostatic field
2) A beam of electromagnetic radiation (infrared, etc)
and looks for changes in the field or return signal.
•The object being sensed -> proximity sensor's target.
•Different proximity sensor targets demand different sensors:
Inductive proximity sensor -> metal target.
Capacitive sensor -> high density target
Photoelectric sensor -> reflective target
Proximity Sensors
9. +18 ~ 30
Volts DC.
0 V
Output
Inductive
Capacitive
Optical
Magnetic
Ultrasonic
Normally open
Normally
closed
Symbol
11. ON
OFF
• Detects all conductive
materials
• Best conductor is mild
steel
• The sensor performance
relies on temperature, the
target material and its
area.
Sensor
Oscillation
Amplitude
Sensor
output
signal
Target
Inductive Sensor
31. Transmitter (T)
/ Receiver (R)
Optical
Sensors
Type :
Diffuse
• Detection distance: less than
reflex type, actual distance
depends on colour and surface
smoothness
• Larger targets enables a longer
detection distance
• No suitable in dirty
environments
T
R