Disposable syringe

Details Disposable syringe Disposable syringe

2002-11-05

2004-06-01

Casler, Brian L. (Department: 3763)

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

C604S192000, C604S218000, C604S240000, C128S919000

Reexamination Certificate

active

06743199

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a disposable syringe, more particularly to a disposable syringe which enables a needle cannula to be retracted within a plunger cavity having a reduced pressure therein.
2. Description of the Related Art
Referring to
FIGS. 1 and 2
, U.S. Pat. No. 5,176,640 discloses a hypodermic injection syringe
10
which includes a barrel
11
, a base
12
fixed to an open front end
111
of the barrel
11
, a needle cannula
13
having a rear needle end
132
that extends into the barrel
11
through the base
12
along an axis and that has an engagement recess
131
, and a plunger
18
slidable within the barrel
11
. The plunger
18
includes a hollow shaft
14
with a vacuum chamber
141
, and a head which has an elastic rubber ring
16
with a channel that is closed by a disc
161
, and a plug
15
with a tube forcibly inserted into the channel of the ring
16
and secured to the shaft
14
. A piston
17
is slidable in a sealed manner within the chamber
141
, and is provided with an engaging rod
172
formed with an elastic flap
171
on a front end thereof.
In use, when the plunger
18
is about to finish its injection stroke, the disc
161
is lacerated by the rear needle end
132
, the rod
172
then engages the needle
13
by engagement of the flap
171
and the engagement recess
131
. In this state, under the action of vacuum present in the chamber
141
, the rod
172
and the needle
13
are sucked into the chamber
141
.
Since the needle
13
can be retained in the chamber
141
of the plunger
18
for safety disposal, the following drawbacks arise:
1. The laceration of the disc
161
may occur when the injection procedure of the syringe
10
is not finished. Thus, some medicine or blood may will remain within the barrel
11
to result in contamination.
2. In order to smoothly suck the needle
13
into the chamber
141
, the securing of the needle
13
to the base
12
cannot be very tight. However, insufficient securing of the needle
13
will result in movement or removal of the needle
13
during the injection procedure.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a disposable syringe which can prevent trapping of medicine or blood therein after injection and which can be operated easily and smoothly to retract a used needle within a plunger.
According to this invention, the disposable syringe includes a needle cannula, a barrel, a tubular barrier member, a tubular needle seat, and a plunger. The barrel has an inner surrounding barrel wall surface surrounding an axis and confining a passage with opposite rearward and forward openings. The inner surrounding barrel wall surface includes a larger-diameter segment and a smaller-diameter segment which confine rear and front passageways, respectively, to form a surrounding shoulder portion therebetween. The smaller-diameter segment includes a smaller front surrounding region and a larger rear surrounding region to form a surrounding abutment wall therebetween. The larger-diameter segment includes proximate and distal surrounding regions respectively proximate to and distal from the surrounding shoulder portion. The proximate surrounding region has a retaining area spaced apart from the surrounding shoulder portion.
The tubular barrier member includes front and rear surrounding edge portions, and inner and outer barrier wall surfaces. The outer barrier wall surface is retained at the retaining area by virtue of a first frictional force generated therebetween while in water-tight engagement with the proximate surrounding region, thereby partitioning the rear passageway into a compressible chamber confronting the surrounding shoulder portion, and an accommodation chamber confronting the rear surrounding edge portion. The inner barrier wall surface has a grip segment.
The tubular needle seat includes a hub portion disposed to fix the needle cannula therein. The hub portion has a surrounding front end wall, a surrounding gripped portion and an anchoring portion. The surrounding gripped portion is retained at the grip segment by virtue of a second frictional force generated therebetween when the surrounding front end wall abuts against the surrounding abutment wall and when the needle cannula is disposed outwardly of the forward opening.
The plunger is movable in the accommodation chamber, and includes a plunger body and a seal member. The plunger body includes a top end wall disposed movably to abut against the rear surrounding edge portion of the tubular barrier member, and a bottom end wall extending outwardly of the rearward opening so as to be manually operable. The top end wall has an inner peripheral edge portion surrounding the axis to define a cavity therein. The cavity extends along the axis and towards the bottom end wall to contain a fluid at a reduced pressure. The seal member is disposed to be sealingly attached to the inner peripheral edge portion along a sealing line so as to trap the fluid in the cavity.


REFERENCES:
patent: 5125898 (1992-06-01), Kaufhold et al.
patent: 5395337 (1995-03-01), Clemens et al.
patent: 6413236 (2002-07-01), Van Dyke
patent: 6572565 (2003-06-01), Daley et al.

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