Sensor applications on white goods

ABSTRACTAppliances like washer, refrigerator, dishwasher, oven and dryer etc. which are known aswhite goods have become the essential part of human life today and at least some of them areavailable in any house. These machines have different types of sensors to perform their basicfunctions. But these sensors don?t have various types and also don?t have complex structures.Usually they are simple electronic components or electromechanical switches/sensors. Forexample, temperature at washing machine, dishwasher, oven and refrigerator is sensed bytemperature sensitive elements such as NTC, PTC or mechanical thermostats, that is the mostcommon sensing application on white goods.Day by day, it is more clearly understood that the technology must be not only user friendly,but also be environment-friendly. This necessity, at the same scope with the aim ofengineering, is obligating all home appliances to be safer, more functional, efficient andintelligent than today they are. For machines, owning these required qualifications is directlyrelated with having knowledge about some critical physical conditions of on their own oraround their environment.The process of integration of sensors with white goods has been started with getting smallerdimensions as many other electronic components with the new material and manufacturingtechnologies. Besides, more superior qualifications, lower costs and being able to reply to thesensitive and cheap sensing necessity, made sensors necessary at home appliances.The aim of this study is to supply know-how and experience for implementation of humidityand gas sensing in oven and refrigerator. In the beginning, a literature research containing alsohygrometry (thermophysical properties of humidity) for learning sensors and technologies fortheir applicability in refrigerator and/or oven has been completed.By using the information obtained from literature, scope of study limited with humiditysensing at built-in electric oven and realized with the determined suitable thermalconductivity sensor (absolute humidity sensor). During this study, the quantity of the foodthat placed in oven can be detected by humidity sensing. In addition it is possible to predictthe kind of food (i.e. beverage, meal or pizza) and sense whether the food is cooked or not.At the last period of the study, the innovative signal conditioning devices have been analyzedfor the processing of sensor outputs and excitation of sensors. Regarding mentioned issue twomixed-signal integrated circuits have been scrutinized with electronics engineering approach,which are Texas Instruments PGA309 ve Cypress Semiconductor PSoC. The ICs performs theall needed process on sensor signals like as temperature drift compensation of offset and span,amplifying, filtering etc. General white goods applications of sensors have been simulated bythe applications with both evaluation modules of PGA309 and PSoC for distinguishperformances of the devices.This document consists of humidity sensor integration especially with built-in electric oven,which is determined by research and several practices, including all periods including sensorplugging to the control system of the devices.Key Words: Sensor, Sensors on white goods, Humidity sensors, Gas sensors, PressureSensor, Sensor technologies, Humidity sensing, Sensor signal conditioning, Humidity sensinginstrumentation, Humidity sensing in electric oven, Humidity sensing in refrigerator,Intelligent oven, Intelligent refrigerator, Thermal conductivity sensor.