Abstract:
A piezoelectric oscillator is described comprising a piezoelectric element, e.g. a tuning fork (10), and a casing (20) formed by a pair of glass plates (22,24). The inner surfaces of the plates have recesses (26,27) that define a housing (28) in which the tuning fork (10) is located, and a pedestal (22a) to which the tuning fork (10) is secured. The inner surface of one of the plates (22) carries a conductive track (30), in the region of the pedestal (22a). This plate (22) is also formed with a hole (44) opening onto the conductive track (30) which seals it off.
Abstract:
A resonator (1) is described for vibrating in a thickness-shear mode and has auxiliary electrodes (7f, 8d) between the zone of its main excitation electrodes (3, 4) and the zone of its connection terminals (5, 6) to generate an auxiliary vibration in opposition of phase with respect to the main vibration.The presence of the auxiliary electrodes (7f, 8d) improves notably the quality factor of the resonator.
Abstract:
A resonator has a parallelepipedal bar of a piezoelectric material designed to vibrate in an extension mode, and suspension means of said bar which form a single, integral part with the latter and which are only connected to one of its lateral faces. This arrangement makes it possible to reduce the number of parasitic vibration modes which could couple to the main mode as well as coupling between these modes, and hence variations as a function of the temperature in the characteristics of the resonator, notably in its quality factor.
Abstract:
Method and apparatus are provided for treating one surface of a wall of articles to be used in contact with blood. A solution which is compatible with blood is brought into contact with the surface and a partial vacuum is applied to the wall for a predetermined time period. This partial vacuum causes gas nuclei trapped in irregularities in the surface to permeate through the wall. Consequently when blood displaces the solution there is less likelihood of blood platelets being trapped on the surface with eventual blood clotting.