感應器

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唔同種嘅光感應器;佢哋喺外形同運作原理上都唔同,但共通點係都會對光有反應,並且將有關探測到嘅光嘅訊息傳去第度。

感應器粵拼gam2 jing3 hei3英文sensor)係機械一種,一部感應器會曉探測某啲事件或者環境改變嘅機械,而且仲識將佢探測到嘅嘢以某啲訊號嘅型式,傳去某啲電子架生嗰度[1][2]

到咗廿一世紀,感應器係好多機械當中都會用到。日常生活常見嘅例子就有𨋢嘅掣(會對人手施嘅壓力有反應,並且將訊號傳去架𨋢嘅控制器嗰度)以及簡單嘅開關(會對人手施嘅壓力有反應,並且將訊號傳去部機械嘅控制器嗰度);另一方面,科研上又會用多種嘅感應器,用感應器量度要研究嘅變數,並且用呢啲訊息驗證佢哋想驗證嘅假說理論[1][3]

一個感應器要具有某啲曉隨「要量度嘅物理量變化」嘅部份,再將呢個部份嘅物理性質轉化做訊號傳出去。想像一個簡單嘅例子說明:有個感應器,要嚟量度溫度(想要量度嗰個物理量);個感應器當中有個容器,容器裝住一種液體,而打前嘅科研經已引證咗,呢種液體嘅電阻會隨住溫度而變化(曉隨要量度嘅物理量變化),而且個感應器喺個容器兩邊駁咗電線;所以當溫度起變化,啲液體嘅電阻會變化,令到通過個容器嘅電流數值(訊號)跟住出現變化-假設溫度、種液體嘅電阻值、以及股電流之間有一柞已知嘅方程式表達出嚟:

係種液體嘅電阻, 係溫度, 係靠之前實驗搵到嘅一個常數
(根據歐姆定律;Ohm's law);
係股電流通過嘅其他部份嘅電阻(股電流唔淨衹會經過啲液體;假設呢個數值已知), 係通過個感應器嘅電壓(呢個數值可以輕易量度), 就係個感應器出嗰股電流。

喺呢個情況下,觀察者就有得靠睇個感應器出嘅電流嘅數值 ,得知個感應器度到嘅溫度 係幾多。

一個感應器嘅敏感度(sensitivity)係指佢輸入每單位變化會引致輸出起幾多變化-反應咗個感應器有幾「敏感」。舉個例,有個溫度計,佢探測到嘅溫度每升攝氏 1 度,個計入面啲液體就會升高 1 厘米,而呢個溫度計嘅敏感度就係 1 厘米每攝氏度(1 cm/°C)[3]

量度誤差[編輯]

工程學上,一個理想嘅感應器有三大特徵[4]

  • 佢對要量度嘅物理量敏感度有返噉上下。
  • 佢對佢喺應用上會撞到嘅第啲物理量敏感度低(唔會因為呢啲物理量有變化)。
  • 佢唔會影響要量度嘅物理量嘅數值。

參考[編輯]

  • M. Kretschmar and S. Welsby (2005), Capacitive and Inductive Displacement Sensors, in Sensor Technology Handbook, J. Wilson editor, Newnes: Burlington, MA.
  • C. A. Grimes, E. C. Dickey, and M. V. Pishko (2006), Encyclopedia of Sensors (10-Volume Set), American Scientific Publishers. ISBN 1-58883-056-X
  • Blaauw, F.J., Schenk, H.M., Jeronimus, B.F., van der Krieke, L., de Jonge, P., Aiello, M., Emerencia, A.C. (2016). Let’s get Physiqual – An intuitive and generic method to combine sensor technology with ecological momentary assessments. Journal of Biomedical Informatics, vol. 63, page 141-149.

睇埋[編輯]

[編輯]

  1. 1.0 1.1 Bennett, S. (1993). A History of Control Engineering 1930–1955. London: Peter Peregrinus Ltd. on behalf of the Institution of Electrical Engineers. ISBN 978-0-86341-280-6The source states "controls" rather than "sensors", so its applicability is assumed. Many units are derived from the basic measurements to which it refers, such as a liquid's level measured by a differential pressure sensor.
  2. Ganesh Kumar (September 2010). Modern General Knowledge. Upkar Prakashan. p. 194.
  3. 3.0 3.1 Jihong Yan (2015). Machinery Prognostics and Prognosis Oriented Maintenance Management. Wiley & Sons Singapore Pte. Ltd. p. 107.
  4. Dincer, Can; Bruch, Richard; Costa‐Rama, Estefanía; Fernández‐Abedul, Maria Teresa; Merkoçi, Arben; Manz, Andreas; Urban, Gerald Anton; Güder, Firat (2019-05-15). "Disposable Sensors in Diagnostics, Food, and Environmental Monitoring". Advanced Materials: 1806739.