Attachment method for piezoelectric elements

Abstract

Disclosed herein is a piezoelectric liquid delivery system or atomizer for production of droplets of liquid or liquid suspensions by means of a battery operated atomizer utilizing an orifice plate in communication with a ceramic piezoelectric element. By use of solder joining to bond the orifice plate to the piezoelectric element, and subsequent repolarization of the piezoelectric element if necessary, superior results are achieved.

Description

PRIORITY[0001] This application claims the benefit of U.S. Provisional Application No. 60 / 123,208, filed Mar. 8, 1999.[0002] The present invention relates, broadly, to the field of atomization of liquids for dispersal in the form of aerosols. More specifically, the invention relates to means for the distribution of a liquid active material, such as a perfume, air freshener, insecticide formulation, or other material, in the form of fine particles or droplets, as in a fine spray, by means of a piezoelectric device. In particular, the invention is directed to a piezoelectric liquid delivery system for the production of droplets of liquid, or liquid suspensions, by means of an electomechanical or electroacoustical actuator. More specifically, the present invention relates to a battery operated piezoelectric dispenser utilizing an orifice plate in communication with a piezoelectric element. It has been found that by joining the orifice plate to the vibrating piezoelectric element by a s...

AI Technical Summary

Benefits of technology

[0009] It is an object of the present invention to provide a highly efficient, consistent, and reliable dispenser for liquid active materials, employing an orifice plate securely joined with a ceramic piezoelectric element. While the invention is described as comprising a ceramic piezoelectric element, it is understood that the invention is not limited thereto, but also extends to other piezoelectric materials having the requisite properties for use, and resistance to the elevated temperatures which accompany joining elements by soldering. By liquid active materials, it is meant to include such liquids as perfumes, air fresheners, household cleaning materials, disinfectants, repellants, insecticides, aroma therapy formulations, medicinals, therapeutic liquids, or other liquids or liquid suspensions which benefit from atomization for use. These compositions may be aqueous, or comprise various solvents. In a preferred embodiment of the invention, the piezoelectric liquid delivery system is easily portable, battery operated, and conveniently refillable with the same, or a different, liquid active

[0011] In still another object, it is desired to provide a liquid delivery system capable of atomizing fragrance oil or insecticide formulation linearly over time, while maintaining the same character / composition on the last day as was delivered on the first, i.e. with no component change or separation with time. The electronics of such a unit may preferably be programmable, and may be used to set a precise delivery rate (e.g. in milligrams per hour, or mg / hr), or may allow the consumer to adjust intensity or effectiveness to a desired level for personal preference, efficacy, or for room size.

[0014] The fragrance or insecticide formulation is supplied to the back side of the orifice plate through a capillary feed system that delivers the liquid in surface tension contact with the plate, without damping the vibrational frequency to which the plate is subjected by the piezoelectric element. The piezoelectric element is driven by a small battery, capable of exciting the element and causing it to force liquid through the orifice plate, which has a multitude of small tapered or conical holes therein perpendicular to the surfaces thereof, the exit of said holes being on the order of 6 microns in diameter. Timing circuitry is used to provide an intermittent excitation to the piezoelectric element so as to dispense small droplets of said liquid in a time dependent fashion. Due to the nature of the liquids being atomized, i.e. the presence of organic components or solvents in the fragrance oils and / or insecticide formulations, it was found that conventional bonding methods for joining the orifice plate to the metallic cantilever beam of a conventional piezoelectric driver were inadequate. Conventional bonding agent exhibit significant degradation over time when in contact with fragrance oils, with the degradation believed to be accelerated by the flexing forces caused by the piezoelectric vibration. A soldering process was developed to eliminate this problem, using a lead / tin solder. In addition, it was found that the orifice plate could be attached directly to a piezoelectric ceramic element, eliminating the need for an extra part such as a cantilever beam or metal amplifying plate.

Problems solved by technology

Such atomizers and / or dispensers fail to provide a system by which liquid to be dispersed is supplied to the vibratory mechanism / surface without resulting in corrosion, solvent activity by the active liquid, or bond failure at the point of joining of the piezoelectric element and the orifice plate, particularly when the active liquids are such as perfumes or insecticides, having high activity quotients at high rates of vibration.

Moreover, the prior art has failed to provide an easily portable, battery operated, continuous-action dispenser employing an orifice plate in soldered connection with a ceramic piezoelectric element, capable of long periods of use with little or no variation in the delivery rate.

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