Transparent/Clear Object Sensor(Glass Sensor)

Group Members

Syed Atif Iqrar (332-FET/BSME/F13) Rashid Saeed (333-FET/BSME/F13) Muhammad Waleed (331-FET/BSME/F13)

Department of Mechanical Engineering, IIU Islamabad

Contents Introduction Transparent object Sensor Types of Transparent object Sensor Ultrasonic Sensor (Clear Object Sensor) Working Principle Ultrasonic sensor construction Characteristics & Considerations Advantages and Disadvantages Applications

Introduction The World of Transparent Materials

Automation specialists have to find their way in the world of transparent materials in many manufacturing processes.

Clear plastic packaging bottles made of glass or PET, vials and dropper Flat, tube and hollow glass

Transparent Object Sensor

To handle various transparent materials in manufacturing industries as well as in robotic industries Transparent Object Sensor are essential

part of manufacturing systems

A transparent object sensor is a photoelectric sensor which is used to detect transparent objects at different ranges for different materials such as glass and plastics of variety of shapes and structures in various

manufacturing processes.

Types of Transparent Object Sensor

There are mainly three types of transparent object sensor

Capacitive Sensor Optical Sensor Ultrasonic Sensor

Capacitive Sensor(Clear Object Sensor)

It works on the principle of changing value of relative permittivity for inserted dielectric.

There are two charged plates held in front of each other with air as dielectric. The conveyer is placed in between the two plates on which the transparent object must be passed.

As the transparent object is passed, the value of relative permittivity of pre-described dielectric is changed.

By measuring how much value of relative permittivity is changed the material of passed object can be found out.

These sensors are used for counting number of objects or level of filled material in transparent object could be determined in large scale production industries.

Working PrincipleMaterial is transparent in our case

Optical Sensor(Clear Object Sensor)

These sensors are also known as photoelectric sensor. Photoelectric sensors provide non-contact accurate detection of

targets. They emit infrared, red or laser light and the target breaks the

light beam or reflects the beam back to the sensor to activate the sensor output.

Photoelectric sensing modes are divided into three primary types, those being through-beam, retro-reflective and diffuse.

Working Principle

Ultrasonic Sensor (Clear Object Sensor)

Ultrasonic sensors emit a sound pulse that reflects off objects entering the wave field.

The reflected sound, or “echo” is then received by the sensor. Detection of the sound generates an output signal for use by an actuator, controller, or computer.

The output signal can be analogue or digital.

Figure:1.1

Working Principle

Ultrasonic sensing technology is based on the principle that sound has a relatively constant velocity.

The time for an ultrasonic sensor’s beam to strike the target and return is directly proportional to the distance to the object

Ultrasonic sensors emit short bursts of high frequency sound waves. When the sound waves strike an object, an echo is reflected to the

ultrasonic sensor. The time it takes for the sound to travel to the object and back to

the sensor (time of flight) is measured and converted into a distance for reliable detection in position and level applications.

Ultrasonic Sensor Construction

There are four basic components of an ultrasonic proximity sensor

Transducer/receiver Comparator Detector circuit Solid-state output

Spacing Considerations

spacing between sensors is determined by their beam angles. The sensors must be spaced so they do not interfere with each

other. This interference is sometimes called “crosstalk.”

Target Considerations

Generally, ultrasonic proximity sensors are affected less by target surface characteristics

however, they require the transducer face be within 3° of parallel to smooth, flat target objects

Target Thermal state

The surface temperature of a target can also influence the sensing range

Radiated heat from high temperature targets distorts the sound beam

Leading to shortened sensing range and inaccurate readings.

Target-to-Sensor Distance

The further a target is away from the sensor the longer it takes the sensor to receive the echo.

Environmental Considerations

There are main four environmental considerations

Ambient Noise Air Pressure Air Temperature Air Turbulence

Advantages & DisadvantagesAdvantages: It’s response is not dependent upon the surface color or optical

reflectivity of the object. For example, the sensing of a clear glass plate, a brown pottery plate, a white plastic plate, and a shiny aluminum plate is the same. 

Ultrasonic sensors with digital (ON/OFF) outputs have excellent repeat sensing accuracy

The response of analog ultrasonic sensors is linear with distance. By interfacing the sensor to an LED display.

it is possible to have a visual indication of target distance. This makes ultrasonic sensors ideal for level monitoring or linear motion monitoring applications.

Advantages & Disadvantages

Disadvantages:

Ultrasonic sensors have a minimum sensing distance Changes in the environment ,such as temperature, pressure,

humidity, air turbulence effect ultrasonic response Targets of low density, like foam and cloth, tend to absorb sound

energy; these materials may be difficult to sense at long range.

Applications

Fill level monitoring PET bottle detection

Applications

Tray, Transparent Beaker detection Filled bottle detection

Applications

Inox, bottle detection in aggressive environment Transparent packaging material detection

Any Query?