A Method To Distinguish The Abnormal Sound Malfunction Of Microspeaker Based On Harmonic Distortion Analysis

To guarantee the function of product,qualitycontrol is one of the important section in the process of the manufacture of microspeakers.To assure and monitor the stability in the production of micro speakers,some companies in both domestic or foreign country install accurate detect instrument on producing line to filter malfunction goods from regular ones.Due to those instruments with complicated calculation and the high precision have some drawbacks such as expensive and lack of quickness,those equipments are not suitable for producing.Most of the manufactories takes the old measure to test the products which is a subjective kind of method,and can easily be influenced by the noise of the environment,and can lead to the wrong judge of the product.And besides the high power and sound pressure of the speakers can cause some serious damage to he listeners' ears.Therefore a new kind of stable,high-efficiency,and can safe kind of test method is urgently needed in the electro-acoustic industry.As for themalfunctioned microspeakers whichare cast aside by produce-line test equipment,there is still lack of such a proper way to find the specificcause reason.Hypothetically,we can distinguish the malfunction mode and analyze the root cause of the invalid products.Then the operators on line can take various methods to deal with different kinds or damage degree of the products.Repairable ones can be sent to the fix work station,and theirreparable ones should be directly isolated.And aiming checking and fixing of the abnormal work spot can be helpful in improving the quality of the merchandise,as long as reducing the waste.In order to fill in the blank in this researching area,this essay is analyzing the different cause reasons of sound malfunction of microspeaker and a practical way to detect,by transforming the responding time domain signal into frequency domain.After briefly introduction of the structural composition,working principal and the testing progress of the coil-moving speaker,this essay did a further research in abnormal sound of the signal.In this paper we emphatically proposed several kinds of root cause of abnormal sound of micro speaker.By analyzing the frequency domain responding signal,we can acquire the data of energy near byor in the high level of the resonance frequency.The first step is to sent the sine stimulus signal into the speaker.And then in the second step,the analog signal can be captured and transformed into digital signal by the data collecting card.And the third part,we use Discrete Fourier Transform to analyze the digital responding signal and draw the distributing chart of the harmony distortion.By comparing the difference of multiple samples of normal and abnormal products' harmony distortion chart,we can discover the main feature of all kinds of malfunction.And also we can divide the malfunction products from the regular ones by setting appropriate limit in particular level of the resonance frequency.