| 摘要 |
PURPOSE:To prevent the deterioration of sensitivity at a low range which is due to the variance of a diaphragm, by setting a sum of a synthetic stiffness of back air chamber and a stiffness of an acoustic load at >=3 times value as high as the equivalent stiffness of the diaphragm. CONSTITUTION:The synthetic stiffness of the 1st and 2nd back air chambers II and III is referred to as S2; and the synthetic stiffness of an acoustic load and an air chamberIis S1 respectively. Then (S1+S2)/S0 is set at >=3 so as to suppress the deviation of sensitivity for (S1+S2)/S0 i.e., the variance of sensitivity to a change of 50% of the S0 of a prescribed (S1+S2)/S0. Within 1dB where S0 is the equivalent stiffness of a diaphragm. Some effect may be given to the sensitivity if the volume is reduced for the chambersIIand III respectively in order to increase the S2. However, the variation of sensitivity can be suppressed down to about 0.2dB even with an estimated allowable dimension at 1/10mm.. As a result, the deterioration of sensitivity can be avoided despite the variance of size of the diaphragm. |
