Transcript Sensors01

感測器原理與應用
•溫濕度感測器
Temperature & Humidity Sensor
Temperature Sensor ( Thermometer)
A thermometer is a device that measures temperature or
temperature gradient using a variety of different principles. A
thermometer has two important elements: the temperature sensor
(e.g. the bulb on a mercury-in-glass thermometer) in which some
physical change occurs with temperature, plus some means of
converting this physical change into a numerical value (e.g. the
visible scale that is marked on a mercury-in-glass thermometer).
http://en.wikipedia.org/wiki/Temperature_sensor
•溫濕度感測器
Temperature & Humidity Sensor
Temperature Sensor ( Thermometer)
http://en.wikipedia.org/wiki/Temperature_sensor
•溫濕度感測器
Resistance thermometer
Resistance thermometers, also called resistance temperature
detectors (RTDs), are sensors used to measure temperature by
correlating the resistance of the RTD element with temperature.
Most RTD elements consist of a length of fine coiled wire
wrapped around a ceramic or glass core. The element is usually
quite fragile, so it is often placed inside a sheathed probe to
protect it. The RTD element is made from a pure material,
platinum, nickel or copper. The material has a predictable change
in resistance as the temperature changes; it is this predictable
change that is used to determine temperature.
http://en.wikipedia.org/wiki/Resistance_thermometer
•溫濕度感測器
Thermocouple
A thermocouple consists of two dissimilar conductors in contact, which
produce a voltage when heated. The size of the voltage is dependent on the
difference of temperature of the junction to other parts of the circuit.
Thermocouples are a widely used type of temperature sensor for measurement
and control and can also be used to convert a temperature gradient into
electricity. Commercial thermocouples are inexpensive,interchangeable, are
supplied with standard connectors, and can measure a wide range of
temperatures. In contrast to most other methods of temperature measurement,
thermocouples are self powered and require no external form of excitation. The
main limitation with thermocouples is accuracy; system errors of less than one
degree Celsius (°C) can be difficult to achieve.
http://en.wikipedia.org/wiki/Thermocouple
•溫濕度感測器
Temperature & Humidity Sensor
Humidity Sensor ( Hydrometer)
A hygrometer is an instrument used for measuring the moisture content in
the environment. Humidity measurement instruments usually rely on
measurements of some other quantity such as temperature, pressure, mass or a
mechanical or electrical change in a substance as moisture is absorbed. By
calibration and calculation, these measured quantities can lead to a
measurement of humidity. Modern electronic devices use temperature of
condensation, or changes in electrical capacitance or resistance to measure
humidity changes.
http://en.wikipedia.org/wiki/Hygrometer
•溫濕度感測器
Temperature & Humidity Sensor
Humidity Sensor ( Hydrometer)
Relative humidity is the ratio of the partial pressure of water vapor in the
air-water mixture to the saturated vapor pressure of water at those conditions.
The relative humidity of air is a function of both its water content and
temperature.
Relative humidity is an important metric used in weather forecasts and reports.
In hot summer weather, a rise in relative humidity increases the apparent
temperature to humans (and other animals) by hindering the evaporation of
perspiration from the skin. For example, according to the Heat Index, a relative
humidity of 75% at 80°F (27°C) would feel like 83.574°F ±1.3 °F (28.652°C
±0.7 °C) at ~44% relative humidity.
http://en.wikipedia.org/wiki/Humidity
•溫濕度感測器
Temperature & Humidity Sensor
Humidity Sensor ( Hydrometer)
The dew point is the temperature below
which the water vapor in a volume of humid air
at a given constant barometric pressure will
condense into liquid water at the same rate at
which it evaporates. Condensed water is called
dew when it forms on a solid surface.
The dew point is associated with relative humidity. A high relative humidity
indicates that the dew point is closer to the current air temperature. Relative
humidity of 100% indicates the dew point is equal to the current temperature
and that the air is maximally saturated with water. When the dew point remains
constant and temperature increases, relative humidity decreases.
http://en.wikipedia.org/wiki/Dew_point
•溫濕度感測器
Temperature & Humidity Sensor
http://www.seeedstudio.com/depot/grovetemperaturehumidity-sensor-pro-p838.html?cPath=144_147
http://www.seeedstudio.com/wiki/Grove__Temperature_and_Humidity_Sensor_Pro
感測器生產廠商
http://www.silabs.com/products/sensors/humiditysensors/Pages/default.aspx