Method for reducing the resonant frequency of a piezoelectric transducer

Claim 3

In a method of reducing the resonant frequency of a piezoelectric audio transducer without altering the predetermined dimensions of said transducer wherein said transducer includes a substrate, a predetermined nodal point location on said substrate, and a piezoelectric element coupled to said substrate operating in a flexural mode of vibration, the improvement which comprises the step of segmenting said substrate to reduce the resonant frequency while maintaining said predetermined nodal point location on said substrate.

Claim 4

In a method of reducing the resonant frequency of a piezoelectric audio transducer without altering the predetermined dimensions of said transducer wherein said transducer includes a substrate, a predetermined nodal point location on said substrate, and a piezoelectric element coupled to said substrate operating in a flexural mode of vibration, the improvement which comprises the step of segmenting said substrate to reduce the resonant frequency while maintaining said predetermined nodal point location on said substrate.

Claim 5

The improved method as recited in claim 2 wherein said step of segmenting said substrate is accomplished by radially cutting at least one slot in said substrate.

Claim 8

The method as recited in claim 4 wherein said slotting extends radially to at least said predetermined nodal point location on said substrate.

Claim 11

The method as recited in claim 6 further comprising the steps of reducing said predetermined thicknesses of said substrate and said piezoelectric element.

Claim 12

The method as recited in claim 7 wherein said step of segmenting said substrate is accomplished by radially cutting at least one slot in said substrate.

Claim 13

The method as recited in claim 8 wherein said slot extends radially to at least said predetermined nodal point location on said substrate.

Claim 14

The method as recited in claim 9 wherein eight (8) slots are each symmetrically cut in said substrate from its circumference to at least said predetermined nodal point location.

Claim 15

In a piezoelectric audio transducer of the type which includes a substrate and a piezoelectric element coupled to said substrate operating in a flexural mode of vibration for producing an audible signal, said transducer having a fundamental resonant frequency and at least one point located on said substrate which is substantially free from vibratory motion when said transducer is driven at said fundamental resonant frequency, the improvement which comprises: means for reducing said fundamental resonant frequency to a substantially lower resonant frequency without relocating said point which is substantially free from vibratory motion, said means for reducing said fundamental resonant frequency including at least one slot radially cut in said substrate.

Claim 16

In a piezoelectric audio transducer of the type which includes a substrate and a piezoelectric element coupled to said substrate operating in a flexural mode of vibration for producing an audible signal, said transducer having a fundamental resonant frequency and at least one point located on said substrate which is substantially free from vibratory motion when said transducer is driven at said fundamental resonant frequency, the improvement which comprises: means for reducing said fundamental resonant frequency to a substantially lower resonant frequency without relocating said point which is substantially free from vibratory motion, said means for reducing said fundamental resonant frequency including at least one slot radially cut in said substrate.

Claim 17

The improved piezoelectric transducer as recited in claim 11 wherein said slot is radially cut to at least said point which is substantially free from vibratory motion.

Claim 18

A piezoelectric audio transducer having a resonant frequency of substantially 2 KHZ and operating in a flexural mode of vibration to produce an audible signal at said resonant frequency comprising: a substrate having at least one point located thereon which is substantially free from vibrating motion when said transducer is driven at said resonant frequency, means provided in said substrate for segmenting said substrate, said segmenting means radially provided to a depth no less than to said point on said substrate which is substantially free from vibrating motion, a piezoelectric element coupled to said substrate, and at least two electrodes electrically coupled to said piezoelectric element.

Claim 19

A piezoelectric audio transducer having a resonant frequency of substantially 2 KHZ and operating in a flexural mode of vibration to produce an audible signal at said resonant frequency comprising: a substrate having at least one point located thereon which is substantially free from vibrating motion when said transducer is driven at said resonant frequency, means provided in said substrate for segmenting said substrate, said segmenting means radially provided to a depth no less than to said point on said substrate which is substantially free from vibrating motion, a piezoelectric element coupled to said substrate, and at least two electrodes electrically coupled to said piezoelectric element.

Claim 20

The piezoelectric transducer as recited in claim 13 wherein said substrate is brass and is a circular disk.

Claim 21

The piezoelectric transducer as recited in claim 14 wherein said piezoelectric element is ceramic and is a circular disk.

Claim 22

The piezoelectric transducer as recited in claim 15 wherein said substrate is segmented by eight (8) slots each symmetrically cut in said substrate from its circumference to at least said point on said circle which is substantially free from vibratory motion.

Claim 23

The piezoelectric transducer as recited in claim 16 wherein said circular brass substrate has a diameter of substantially 1.375 inches.

Claim 24

The piezoelectric transducer as recited in claim 17 wherein said circular brass substrate has a thickness of substantially 0.008 inches, said circle on said substrate has a diameter of substantially 0.875 inches, and said circular ceramic piezoelectric element has a thickness of substantially 0.008 inches and a diameter less than said diameter of said circle on said substrate.

Claim 25

In an audible alarm device which includes means for housing a piezoelectric transducer having a circular substrate with a predetermined diameter, a circular piezoelectric element coupled to said substrate, a fundamental resonant frequency and a fundamental nodal diameter wherein said transducer is mechanically coupled to said housing means at at least one point on a circle having a diameter equal to said fundamental nodal diameter, the improvement which comprises: means for reducing said fundamental resonant frequency of said transducer to a substantially lower resonant frequency without necessitating a change in said means for housing said transducer, said frequency reducing means including at least one slot radially cut in said circular substrate to at least said fundamental nodal diameter.

Claim 26

In an audible alarm device which includes means for housing a piezoelectric transducer having a circular substrate with a predetermined diameter, a circular piezoelectric element coupled to said substrate, a fundamental resonant frequency and a fundamental nodal diameter wherein said transducer is mechanically coupled to said housing means at at least one point on a circle having a diameter equal to said fundamental nodal diameter, the improvement which comprises: means for reducing said fundamental resonant frequency of said transducer to a substantially lower resonant frequency without necessitating a change in said means for housing said transducer, said frequency reducing means including at least one slot radially cut in said circular substrate to at least said fundamental nodal diameter.