Ultrasonic Sensor Seminar Report

C. CONSTRUCTION AND COMPONENTS OF ULTRASONIC SENSORS

Fig.3 Small Pin-Connector Type Ultrasonic Sensor The Fig.3 shows a small pin connector type ultrasonic sensor.It consists of a flexible substrate for connecting a piezoelcetric ceramic device and a pin connector inside the sensor.It has characteristics similar to lead wire type ultrasonic sensors but it small in size as compared to the lead type ultrasonic parking sensor. The connecting process stablizes the charschteristics and improves productivity. It is very advantageous to meet the requirement to improve the resistance characteristics for electromagnetic noise due to advancements in digital signal processing.

Fig 4. Ultrasonic Proximity Sensor Components

• Transducer

The maximum sensing distance is the distance at which the sensor is capable to see the object. The harder the object the shorter will be the maximum sensing distance.
Materials that absorb sound for example foam, cotton, rubber, etc. are more difficult to detect than acoustically reflective materials, like steel, plastic, or glass. Fig . 6 shows the sensing ranges for such materials. Non target materials can be hidden by covering them with sound absorbent material.

Fig 6. Sensing range with maximum sensitivity
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Fig 7. Effective beam

Fig.7 explains the concept of effective beam. When the transducer vibrates, it emits ultrasonic pulses that propagate in a cone-shaped beam. Using a potentiometer this cone can be adjusted to widen or extend the sensing range

Beam angles are responsible for spacing between the sensors. The sensors must be spaced so they do not interfere with each other. This interference is sometimes called “crosstalk.”

Fig 8. Spacing of Ultrasonic Sensors

When more than one ultrasonic sensor is in use, in such applications the following guidelines should only be used as a reference. Fig.9 Spacing