電容式麥克風量測加速度之可行性研究

Abstract

雖然加速度計的使用已發展多年，但仍因價格昂貴、取得不易、使用上需要信號調節器配合等等因素而造成研究上並不是這麼的便利，所以在考量是否有價格低廉、取得容易、使用上的配套設備容易製作的感測器可取代，因此對駐極體電容式麥克風進行研究，若駐極體電容式麥克風亦可用來量測加速度，對於實驗與研究將大有助益。 本論文首先介紹常見加速度計及加速度計用來量測加速度的理論推導，再進一步推導理論上駐極體電容式麥克風可以用來量測加速度，又透過一系列實驗驗證確實可以量測加速度且有其規格。靈敏度有常數增益其誤差5%的範圍為225Hz~2820Hz、誤差範圍10%的範圍為200Hz~3015Hz、誤差範圍50%的範圍為50Hz~5025Hz。當以麥克風量測加速度時，側向靈敏度相當高，從實驗數據可發現可在低於4000Hz範圍是高於35%的，以麥克風量測加速度時，此缺點還有待改善。針對加速度計有方向性，麥克風無方向性的問題，在使用麥克風量測上可考慮以三個不同方向的垂直軸量測進一步量測方向性。

Although the use of accelerometers has been developed for many years, accelerometers are still not so convenient because of its high price, difficulty in obtaining, and the need for signal conditioners in use. Therefore, electret condenser microphones are considered that they are cheap, easy to obtain, and easy to use. Sensors that are easy to make on the matching equipment can be replaced. Therefore, research on electret condenser microphones can be used for experiments and research if the electret condenser microphone can also be used to measure acceleration. This paper first introduces the theoretical derivation of common accelerometers and accelerometers for measuring acceleration, and further deduces that the theoretical electret condenser microphone can be used to measure acceleration, and through a series of experiments to verify that the acceleration can be measured and Its specifications. The sensitivity has a constant gain with a range of 5% ranging from 225 Hz to 2820 Hz, an error range of 10% ranging from 200 Hz to 3015 Hz, and an error range of 50% ranging from 50 Hz to 5025 Hz. When the acceleration is measured by the microphone, the transverse sensitivity is quite high. It can be found from the experimental data that it can be higher than 35% in the range below 4000 Hz. When the acceleration is measured by the microphone, this disadvantage needs to be improved. For the problem that the accelerometer has directionality and the microphone has no directivity, it can be considered to measure the directivity by using the vertical axis measurement in three different directions.