Shear mode transducer for drop-on-demand liquid ejector

In a pressure pulse droplet ejector:

• a housing containing at least two fluid pressure chambers, said housing having a portion thereof forming an opening into each said chamber,
• means extending across said openings of said chambers to form a deformable wall of each of said chambers, said means comprising a piezoelectric transducer, the portion of said piezoelectric transducer which is adjacent the perimeter of said portion of a respective said fluid pressure chamber forming said opening being restrained against movement relative to said housing,
• said piezoelectric transducer having first and second polarized portions, one for each chamber, which are free for reciprocal deformation relative to said housing in the general direction of polarization, the direction being generally transverse to the direction in which said piezoelectric transducer extends across said openings,
• first means for applying an electrical field to said first polarized portion substantally orthogonal to the polarization field to cause said first polarized portion to deform in shear in the general direction of polarization to vary the volume of its respective chamber, and
• second means for applying an electrical field, independently of the electrical field applied to said first portion, to said second polarized portion substantially orthogonal to the polarization field to cause said second polarized portion to deform in shear in the general direction of polarization to vary the volume of its respective chamber chambers.