The invention relates to piezo-electric actuating elements for recording heads in mosaic-type recording equipment, in particular those wherein a recording ink or fluid contained in a compression chamber, surrounded by the cylindrical actuating element, is forced out in drops through piezo-electric constriction of the actuating element.
The use of the piezo effect to operate recording heads has been known for a long time. German Inspection specification No. 2,405,584, for example, describes a pulse drop injection system in which a glass tube is encircled by a piezo-electric transducer which constricts in synchronism with a pulse generator and thereby forces recording fluid in the glass tube to be discharged drop by drop.
Recording tubes of this type are supported in holding devices within which the entire electro-mechanical transducer is firmly embraced by clamping means, with the external electrode of the transducer being secured to such holding device. Consequently, a loosening of the recording tube and holding device, as a result of any change in the external diameter resulting from constriction of the transducer, must be avoided as such loosening would automatically become noticeable from the resulting deterioration in the quality of the recording.