Surgery – Instruments
Patent
1994-06-01
1995-09-05
Aschenbrenner, Peter A.
Surgery
Instruments
604 22, 607 97, A61H 2300
Patent
active
054475104
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an apparatus comprising an ultrasonic probe for removing biologic tissue, said apparatus being of the type described in the preamble of claim 1. The invention also relates to a method for producing a preferred embodiment of the apparatus.
BACKGROUND OF THE INVENTION
In apparatuses of this kind the probe, the armature, to which is it fastened, and one or more piezoelectric crystals form an oscillating system with a resonance frequency corresponding to the frequency, at which work is desired to be carried out. In the known apparatuses the piezoelectric crystals are shaped like discs placed perpendicular to the axis of the probe and fixed with a mounting of the crystal in such a way that an electric activation brings about a mechanical change of the crystal in the axial direction of the probe. To attain a sufficient mechanical effect the crystal should have a certain area, which makes it necessary that the housing in order to hold the crystals should have a diameter of 20 nm or more. The comparatively big diameter of the cross-section of the housing makes the apparatus awkward to hold, which makes it in particular tiring to work with when very precise movements are to be carried out with the point of the probe, which is of particular importance when such apparatus are used for surgical interventions in human eyes, in which connection work is carried out with the apparatus under microscope. The comparatively big dimensions of the crystal or the crystals also contribute to making it difficult to attain very high resonancy frequencies on account of the comparatively big masses of armature and probe. It is thus difficult to attain resonance frequencies in the area of 50 to 100 kHz.
OBJECT AND SUMMARY OF THE INVENTION
The object of the invention is to provide an apparatus of the above-mentioned type, but in connection with which it is possible partly to reduce the diameter of the housing, partly to attain resonancy frequencies in the area between 50 and 100 kHz without any specific measures.
This object is met by the apparatus according to the invention and mentioned by way of introduction, said apparatus being characteristic in the subject matter of the characterizing clause of claim 1.
In the apparatus according to the invention, the armature, on which the probe is fastened, is most compact and consequently of a limited mass, which contributes to increasing the resonance frequency. The armature is directly suspended in the two, three or four piezoelectric crystals acting in shear mode. These crystals form a comparatively rigid suspension, which also contributes to giving the system comprising armature and probe a high resonance frequency. As the piezoelements are placed in the longitudinal direction of the probe, they can be given a comparatively big area without affecting the diameter of the apparatus. The diameter of the apparatus may therefore be small and contained in a very slim housing, an instrument being thus provided which is easy to work with. The design is in particular favourable in connection with apparatuses aiming at an axial vibration of the probe, but is in special embodiments also applicable in apparatuses, where the ultrasonic vibration produces a vibration perpendicular to the axis of the probe. However, the latter embodiment requires that only two piezo elements be used, and that they are oriented in such a way the they act in shear mode perpendicular to the axis of the probe, but still, however, in such a way that the plane of the piezo elements is running parallel to the axis of the probe. Whereas the apparatus with the axial vibration is in particular suited for eye operations, the other apparatus vibrating perpendicular to the longitudinal direction of the probe will be suited for cleaning operations, for instance removal of plaque and tartars from teeth.
According to a preferred embodiment of the apparatus the armature and preferably also the segments placed between the piezo bodies and the sleeve are made from anodized alum
REFERENCES:
patent: 4886060 (1989-12-01), Wiksell
patent: 4974581 (1990-12-01), Wiksell
patent: 4989588 (1991-02-01), Kubota et al.
patent: 5069664 (1991-12-01), Guess et al.
patent: 5112300 (1992-05-01), Ureche
patent: 5167619 (1992-12-01), Wuchinich
patent: 5242385 (1993-09-01), Strukel
patent: 5267954 (1993-12-01), Nita
Aschenbrenner Peter A.
Baltic Technology ApS
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