Capacitive Type Transducer
- 1. SESSION: 2017-18 CAPACITIVE TYPE TRANSDUCER Submitted by:- Krishna Kant Nayak Student of MNIT, Jaipur
- 2. Introduction Work Principle Parameters of capacitive transducer Application of capacitive transducer
- 3. Introduction Moreover, the capacitive transducer or sensor is nothing but the capacitor with variable capacitance “Capacitive type means using capacitance and transducer means a device that converts variations in a physical quantity, into an electrical signal”
- 4. Working principle The capacitive transducer comprises of two parallel metal plates that are separated by the material such as air, which is called as the dielectric material. In the typical capacitor the distance between the two plates is fixed, but in variable capacitance transducers the distance between the two plates is variable.
- 5. The capacitanceC between the two plates of capacitive transducers is given by: C= (ε0 x εr xA)/ d Where, C -The variable capacitance transducer ε0 - absolute permittivity εr - relative permittivity The product of ε0 & εr is also called as the dielectric constant of the capacitive transducer. A - area of the plates D - distance between the plates
- 6. Changing Area of the Plates of CapacitiveTransducers Changing Distance between the Plates of Capacitive Transducers Changing Dielectric Constant type of Capacitive Transducers Parameters for Capacitive Transducers
- 7. Application of capacitive transducer Capacitive type transducers has wide range of applications in which s0me of them are: In Microphones In Semiconductor Industries In Detecting Dynamic Motion
- 8. In Microphones An increase of distance between the parallel plates will decrease the capacitance value correspondingly. This transducer is used to convert the value of displacement or change in pressure in terms of frequency.
- 9. • As shown in the figure , A capacitive transducer has a static plate and a deflected flexible diaphragm with a dielectric in between.When a force is exerted to the outer side of the diaphragm the distance between the diaphragm and the static plate changes.This produces a capacitance which is measured using an alternating current bridge or a tank circuit. • A tank circuit is more preferred because it produces a change in frequency according to the change in capacitance.This value of frequency will be corresponding to the displacement or force given to the input.
- 10. Capacitive sensors are used for the precise positioning of semiconductor down to nanometer level for exposure in different electrical and electronic circuits. Semiconductor industry
- 11. Capacitive transducers are ideal for the measurement of dynamics of a continuously moving target such as rotating spindles or vibrating element like in disc drive spindles. Detecting Dynamic Motion
- 12. Liquid level measurement by changing the capacitance between two conductive plates. Capacitors are common force sensors. Commonly used forThickness measurement in a noncontact fashion.
- 13. Advantages High sensitivity Can detect upto 10^-14 m displacements Low power requirement High resolution Low cost Easy to integrate into ICs
- 14. Disadvantages Performance is severely effected by dirt and other contaminants. The metallic part must be insulated from each other. Affected by temperature and humidity Sensitivity to noise Difficulties in designing Non-linearity
- 15. References www.electronicdesign.com www.instrumentationtoday.com https://en.wikipedia.org http://www.brighthubengineering.com/hvac /53147-how-capacitive-transducers-work/ http://kalpanatamvada.tripod.com/