Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2003-03-11
2004-09-28
Mendez, Manuel (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S192000
Reexamination Certificate
active
06796961
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a hypodermic syringe and, more particularly, to a safety hypodermic syringe, which enables the needle assembly to be automatically received inside the barrel upon a return stroke of the plunger after a rotary motion of the plunger.
2. Description of the Related Art
When disposing of a disposable hypodermic syringe after its service, the person handling the disposable hypodermic syringe may be injured by the protruding needle cannula accidentally. In order to eliminate this problem, safety hypodermic syringes are developed. These safety hypodermic syringes enable the needle assembly to be pulled backwards with the plunger and received inside the barrel after the service. Exemplars of these safety hypodermic syringes are seen in Taiwan Patent Publication Nos. 189436; 356013; 463639; 414085; 384709; 359621; 492328; 467752; 475449; 480185; 497976; 430565; 471322; 332433; 394027; and 447310, and U.S. Pat. Nos. 5,385,557; 4,747,830; 4,677,980; 5,242,400; 4,986,813; 4,947,863; 5,533,975; 5,171,300; 4,944,723, . . . etc.
FIG. 1
shows a safety hypodermic syringe according to the prior art. According to this design, the safety hypodermic syringe comprises a barrel
11
, the barrel
11
having a front socket
12
and two raised portions
121
protruding from the inside wall of the front socket
12
, a needle hub
13
mounted in the front socket
12
, the needle hub
13
having two angled crevices
131
extended to the front side and respectively coupled to the raised portions
121
of the front socket
12
, and a bottom retaining hole
132
, and a plunger and stopper assembly
14
inserted into the barrel
11
from the rear side, the stopper assembly
14
having a front engagement tip
141
adapted to engage the bottom retaining hole
132
of the needle hub
13
.
FIG. 2A
shows the safety hypodermic syringe assembled. This design of safety hypodermic syringe is seen in U.S. Pat. No. 5,273,543. It has drawbacks as outlined hereinafter.
1. The raised portions
121
of the front socket
12
are respectively stopped at the end of the rear horizontal section of the angled crevices
131
when the safety hypodermic syringe assembled. When removing the needle hub
13
from the front socket
12
after the service of the hypodermic syringe, the user must rotate the needle hub
13
with the plunger
14
in the assigned direction. When rotating the plunger
14
in the wrong direction, the connection between the needle hub
13
and the raised portions
121
of the front socket
12
is reinforced, unable to remove the needle hub
13
from the raised portions
121
.
2. Because the contact
15
between the needle hub
13
and the front socket
12
is a planar contact, the outer diameter of the needle hub
13
must be made to be press-fitted into the inner diameter of the front socket
12
to prevent a leakage. Due to high friction resistance between the outside wall of the needle hub
13
and the inside wall of the front socket
12
, the user must employ much effort to the plunger
14
to pull the needle hub
13
and the needle cannula
133
back to the inside of the barrel
11
after the service of the safety hypodermic syringe (see FIG.
2
B).
There are known other designs of safety hypodermic syringes that use a screw joint to secure the neck hub in position. These designs are seen in U.S. Pat. Nos. 4,944,723; 4,978,340; 5,171,300; 4,947,863; 4,986,813. Other needle hub positioning designs are seen in Taiwan Patent Publication Nos. 492328; 356013; 359621; 463639, etc., and U.S. Pat. Nos. 5,242,400; 4,747,830; 5,098,390; 5,370,619; 4,911,693, etc. These prior art designs still cannot eliminate the aforesaid drawbacks.
Therefore, it is desirable to provide a safety hypodermic syringe that eliminates the aforesaid drawbacks.
SUMMARY OF THE INVENTION
The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a safety hypodermic syringe, which enables the needle assembly to be conveniently received inside the barrel after the service of the safety hypodermic syringe. It is another object of the present invention to provide a safety hypodermic syringe, which enables the needle assembly to be automatically received inside the barrel upon a return stroke of the plunger after a rotary motion of the plunger.
To achieve these and other object of the present invention, the safety hypodermic syringe comprises a barrel, the barrel comprising a body and a socket at a front side of the body; a needle assembly, the needle assembly comprising a needle hub mounted in the front socket of the barrel, the needle hub having a bottom coupling hole, and a needle cannula forwardly extended from the needle hub outside the barrel; and a plunger and stopper unit, the plunger and stopper unit comprising a stopper fitted into the body of the barrel, and an elongated plunger backwardly extended from the stopper to the outside of the barrel and adapted to reciprocate the stopper in the body of the barrel, the stopper having a front engagement tip adapted to engage the bottom coupling hole of the needle hub for enabling the needle assembly to be pulled backwards with the plunger and stopper unit and received inside the body of the barrel. The socket of the barrel has at least one small stub rod protruding from the inside wall. The needle hub of the needle assembly comprises at least one sliding groove formed in the periphery and respectively coupled to the at least one small stub rod of the socket, for enabling the needle assembly to be pulled backwards with the plunger and stopper unit and received inside the body of the barrel after a rotary motion of the plunger relative to the barrel. The at least one sliding groove each has two distal open ends through which the at least one small stub rod of the socket is moved in and out of the at least one sliding groove when the plunger and stopper unit and the barrel are rotated relative to each other, and a positioning portion on the middle between the two distal open ends for engagement with the at least one small stub rod of the socket. Further, the sliding grooves of the needle hub can be made having a substantially U-shaped profile, or a V-shaped profile.
REFERENCES:
patent: 4986813 (1991-01-01), Blake et al.
patent: 5393301 (1995-02-01), Goldberg
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