Surgery – Instruments – Cutting – puncturing or piercing
Reexamination Certificate
2000-01-26
2001-10-09
Thaler, Michael H. (Department: 3731)
Surgery
Instruments
Cutting, puncturing or piercing
C606S183000
Reexamination Certificate
active
06299626
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to skin prickers.
BACKGROUND TO THE INVENTION
The need to avoid medical personnel accidentally being cut or pricked by surgical instruments has become of critical importance since the advent of viruses which are transmitted by contaminated blood, and which lead to serious or fatal diseases.
There is now much prior art on this subject and Applicant is aware of US Specifications 5147375, 5611809 and 5487748 which disclose skin prickers having arrangements for rendering them safe after use.
The present invention seeks to provide a skin pricker of improved construction.
BRIEF DESCRIPTION OF THE INVENTION
According to the present invention there is provided a skin pricker having a casing and a plunger which are displaceable with respect to one another when the plunger is placed against the skin to be pricked and the casing is pushed towards the plunger to trigger operation of the skin pricker, the skin pricker further including a lancet blade, a spring acting on the lancet blade for urging the lancet blade in a skin pricking forward stroke and then withdrawing it to an inoperative position, said blade being displaced with respect to the casing by the plunger during an initial part of the relative displacement between the plunger and casing, energy being stored in the spring during such initial movement, and the blade being disconnected from the plunger upon relative movement between said casing and plunger exceeding said initial part thereby to permit the spring to exert itself and urge said blade in said forward stroke relative to the casing and the plunger.
The skin pricker can have stop means for limiting movement of the lancet blade said stop means becoming effective upon said casing completing said initial part of its movement with respect to the plunger.
In the preferred form said spring is of sinusoidal form and includes a series of waves, the spring including stops for limiting closing-up of the waves, said stops constituting said stop means.
To limit the force needed to compress the spring, it can include a series of thinner curved portions joined by thicker generally straight portions.
To improve the prospects of drawing blood said blade can have two points for pricking the skin at two adjacent locations.
In one constructional form said blade is secured to an element which includes at least one shear pin which initially is contacted by a surface of the plunger so that the plunger and element form a unit and the casing moves relatively to this unit, said pin being sheared of by said surface when said stop means becomes effective to limit further movement of said element with respect to the casing thereby to permit the spring to exert itself and urge said blade and element in said forward stroke.
In another constructional form said blade is secured to an element which includes at least one cam which is initially contacted by a surface of the plunger, and is displaced by that surface, so that the plunger and element form a unit and the casing moves relatively to this unit, said surface being on a plate which is resiliently flexible, said cam temporarily camming said plate to a deflected position upon said stop means becoming effective to limit further movement of said element with respect to the casing so that said cam disengages from said surface and the element and blade are free from restraint by the plunger thereby to permit the spring to exert itself and urge said blade and element in said forward stroke.
Said plate desirably has an elongate slot in it which said cam enters and can thereafter move along after camming said plate to its deflected position and disengaging from said surface.
To facilitate assembly, said plunger fits telescopically into an open end of said casing, there being interengaging elongate grooves and latches for preventing said plunger being removed from the casing after insertion whilst permitting relative telescopic movement.
In a specific form said blade is secured to an element which includes at least one cam which is initially contacted by a surface of the plunger, and is displaced by that surface, so that the plunger and element form a unit and the casing moves relatively to this unit, said surface being on a plate which is resiliently flexible, said cam temporarily camming said plate to a deflected position upon said stop means becoming effective to limit further movement of said element with respect to the casing so that said cam disengages from said surface and the element and blade are free from restraint by the plunger thereby to permit the spring to exert itself and urge said blade and element in said forward stroke, said plunger including a head and a parallel spaced pair of said plates protruding from a rear face thereof, said head having an opening in it through which said blade projects during said forward stroke.
According to a further aspect of the present invention there is provided a generally sinusoidal spring having a series of bends joined by a series of generally straight portions, the bends being thinner than the straight portions.
REFERENCES:
patent: 4677979 (1987-07-01), Burns
patent: 4991827 (1991-02-01), Taylor
patent: 5147375 (1992-09-01), Sullivan et al.
patent: 5395387 (1995-03-01), Burns
patent: 5439473 (1995-08-01), Jorgensen
patent: 5540709 (1996-07-01), Ramel
patent: 6062548 (2000-09-01), Nagao et al.
patent: 6113620 (2000-09-01), Chung
patent: 0293092 (1988-11-01), None
Ladas & Parry
Thaler Michael H.
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