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1. Oscillator

2. Photoelectric emitter

3. Photoelectric receiver

4. Preamplifier

5. Logic Operations

6. Pulse/Level

7.Switching status display

8.Output stage with protective circuit9.External Voltage

10.Internal constant voltage supply

11.Optical switching distance

12.Switch output

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Optical Sensors

Red and Infrared light is used.

Emitter (LED) and Receiver. (photodiode

and phototransistor)

Objected may be reflective, matt,

opaque.high proportion of light to be

reflected directly or diffusely.

Operating switching distance varied by

potentiometer.

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Optical Sensors

Receiver is tuned to pulse of the emitter.

Emitter:

Without fiber optic-800nm (non visible,infrared)

With fiber optic 660nm

Single fiber optic 20,000

Built in protective measures (reversepolarity protection, Sc protection outputs,voltage peaks)

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Optical Sensors

Through Beam Diffuse

Retro reflective

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Through beam

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Through beam

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Through beam

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Through beam

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Through beam

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Through beam

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Through beam

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Response of through beam

sensors

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Advantages

Enhanced reliability because of permanent

light during non operation.

Wide range

Small objects can be detected at large

distances.

Good positioning accuracy

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Disadvantages

Two separate proximity sensor modules

(emitter and receiver) and separate

electrical connections are required,

Cannot be used for completely transparent

objects.

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Retro reflective

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Retro reflective

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Retro reflective

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Retro reflective

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Retro reflective

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Response of retro reflective

sensors

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Advantages:

Enhanced reliability because of permanent

light during non-operation.

Simple installation and adjustment.

Greater range in comparison with diffuse

sensors.

Only passive reflector is required on oneside of the conveyor without the need of

electrical cabling for receiver.

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Disadvantages:

Transparent, very bright or shiny objects

may remain undetected.

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Diffuse Sensor

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Diffuse Sensor

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Diffuse sensor

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Response range of diffuse sensor

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Advantages

Reflection on the object activates the

receiver, an additional reflector is not

required.

With through beam sensors objects can

only be detected laterally to the light

beam, diffuse sensors allow frontal

detection.

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Disadvantages

Response curve is not straight

Diffuse sensors are not suitable as

through beam sensors, if accurate lateral

response is crucial.

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Optical Sensors with fiber optic

cables

Fiber optic cables adapters are used if

conventional devices take up too much

room, areas with hazard.

Advantages: Position of small objects can

be detected with high accuracy.

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Advantages of fiber optic cables

Detection of objects in areas of restricted

access.

Possibility of remote installation of

proximity sensor housing.

Accurate detection of small objects.

Sensing elements can be moved.

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Advantages of polymer fiber optic

cables

Mechanically stronger than fiber glass.

Length can be reduced easily by cutting

the ends on the proximity sensors with a

sharp knife.

Cost saving.

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Advantages of glass fiber optic

cables

Suitable for high temperature.

Reduced optical attenuation with large

distances as well as at close infrared

range.

Longer lasting.

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