Photoelectric sensors

Presented by:Darshil Shah

IU1241090051

Content

What is photoelectric sensor?

Sensing mode

Working, Advantages & Disadvantages of sensing modes

Application

What is photoelectric sensor?

• A photoelectric sensor, or photo eye, is a device used to detect the distance, absence, or presence of an object by using a light transmitter, often infrared, and a photoelectric receiver

• The output signal can be analog or digital and is often internally modified with timing logic, scaling, or other signal processing prior to output

Sensing modes

Through beam

Retro-reflective

Diffused beam

Through-beam

Working:The transmitter and receiver of the thru beam sensor are housed in different cases that are separated from each other. The Emitter (E) transmits directly to the receiver (R). If an object (O) interrupts the light beam, the receiver voltage drops and the switching function is initiated

E R

O

Advantages :1. Most accurate.2. Longest sensing range.3. Very reliable.

Disadvantages:1. Must install at two points on system: emitter and receiver.2. Costly - must purchase both emitter and receiver.

Retro-Reflective

Working: The retro-reflective sensor contains the emitter and receiver in a single housing. The light from the transmitter is beamed back from a reflector to the receiver. If the beam of light is interrupted, the switching function is initiated

Advantages:1. Cost less 2. Sensing range better and Very reliable

Disadvantages:1. Must install at two points on system: sensor and reflector2. Slightly more costly than diffuse3. Sensing range less than through-beam

Diffused-beam

Working:The structure of the diffuse mode sensor is based on the same principle as a retro-reflective sensor. It does not have a reflector, however. Instead, the light reflected from the recorded object is evaluated by the receiver.

Advantages:1. Only install at one point2. Cost less than through-beam or reflective

Disadvantages:1. Less accurate than through- beam or reflective2. More setup time involved

Applications

1. Piled up ice cream cupsThrough beam laser sensor detects piled up ice cream cups.Small spot size of laser finds slight changes in tallness.

2. Through beam laser sensors we use water detection detects whether transparent bottle is filled with clear liquid or not

3. Defects seal on instillation bags.When it's sealed, diffuse sensor detects upper edge of the bag and finds its distortion

4. If flowing can is fallen down, some sensor does not detect anything and find trouble. As Reflective laser sensor, stable detection without influences from designed print and glaze can be available.

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References