Patent EA-002498-B1 (EA)
Title: Acoustic device comprising a panel member relying on bending wave action
Inventor: AZIMA HENRY
IPC: H04R7/04
Filed: 1999-02-09
Abstract: 1. A method of making an acoustic device relying on bending wave action in an area of a panel member, the method comprising selecting a shape parameter to be varied, said parameter is selected from the group including configuration of said area of the panel member, the bending stiffness of said area of the panel member, and the location of bending wave transducers in said area of said panel member, selecting said shape parameter in accordance with said power transfer, said shape parameter is a function of at least one of the shape parameters and that said shape parameter is selected from the group comprising a mechanical impedance to the input power transfer and power output, vary the shape parameter and analytical assessment of measurement in accordance with the parameter power transfer as a function of the parameter shape, selecting the value of the shape parameter, which provides the minimum or minima of deviation of the said power transfer related parameter from a value or relation therefor and the smoothness of power transfer is reached and, consequently, satisfied characteristics of the acoustic device in a desired frequency range. 2. Method according to claim 1, including compensating for any deviation from flatness of output power by correlated conditioning of the input to the acoustic device  3. Method according to claim 1, or 2 in which the power transfer related parameter is mechanical impedance. 4. Method according to Claim 3, wherein the analytical assessment includes determining the standard deviation of the mechanical impedance from some value or relation therefor. 5. Method according to claim 4, wherein the deviation is relative to same or unity weighting applied for resonant frequency modes involved. 6. Method according to claim 4 or 5, wherein the deviation is relative to mean values for resonant frequency modes involved. 7. Method according to any of claims 4 to 6, wherein the deviation is relative to selective weighting for resonant frequency modes involved. 8. Method according to claim 7, wherein the selective weighting is applied for end-most resonant frequency model(s) involved. 9. Method according to claim 8, wherein the end-most resonant frequency modes involved are lowest in frequency range of interest for desired or acceptable operation of said acoustic device. 10. Method according to any preceding claim, wherein the panel member is or is considered as substantially rectangular, and resonant frequency modes involved in the analytical assessment arise from making simplifying analogy to orthogonal beams notionally in directions parallel to pairs of opposite sides of said panel members. 11. Method according to any preceding claim, wherein resonant frequency modes involved in said analytical assessment arise relative to two-dimensional relationships of the panel member as such. 12. Method according to any preceding claim, wherein said selecting is as to proportions of shape of said panel member. 13. Method according to claim 12, wherein said selecting is assisted by presenting smoothed results of said analytical assessment as mechanical impedance of said panel member against varying said shape proportions to show minima of deviation. 14. Method according to claim 12 or claim 13, wherein said analytical assessment is for given transducer location(s). 15. Method according to any preceding claim, wherein said selecting is as to location of transducer means for a given said panel member. 16. Method according to claim 15, wherein said analytical assessment is for variable one relative to fixed other of co-operative areal locators such as coordinates of transducer location and results are presented functionally, usefully graphically, in looking for minimum deviation of preferably smoothed mechanical impedance. 17. Method according to claim 16, wherein alternate said assessments involve alternation as to which areal locator is fixed and which variable. 18. Method according to any preceding claim, wherein said analytical assessment includes distribution of mechanical impedance of said panel member on areal basis. 19. Method according to claim 18, wherein said selecting is assisted by presenting results of said analytical assessment as contour mapping of areal deviation of mechanical impedance. 20 Method according to claim 19, wherein said analytical assessment and contour mapping is of one only of two or more notional parts of the same or similar geometry that together substantially match area of said panel member. 21. Method according to claim 20,wherein said analytical assessment and contour mapping is of one quadrant for a substantially rectangular shape of said panel member. 22. Method according to any preceding claim including the step of selecting panel member shine proportion and the step of selecting transducer location wherein one of the two said steps of selecting is done at least once after and using results of doing the other said step.