Safety syringe abstract
A safety syringe for intravenous injection with a guided plunger
is provided that comprises a barrel, a needle unit, and a plunger.
An outlet is eccentrically disposed on the top of the barrel. The
needle unit includes a needle and a spindle shaped needle holder
mounted inside the outlet. A connecting stem has an arrowhead shaped
mortise disposed under the spindle shaped needle holder. A plunger
has a plunger head on the top thereof with an arrowhead shaped tenon
eccentrically disposed thereon. A supporting plate disposed under
the plunger head has two guide notches matched with two longitudinal
guide strips inside the barrel, so that the arrowhead shaped tenon
aligns with the needle unit. After completion of the injection,
the arrowhead shaped tenon and the needle unit are connected together,
the needle unit can then be pulled into the barrel and subsequently
deformed.
Safety syringe claims
What is claimed is:
1. A safety syringe for intravenous injection, comprising:
a barrel having a conically shaped front portion and an opposing
rear portion with an outwardly extended flange formed thereat, said
barrel having a bore formed therein and said rear stem having an
opening formed in open communication with said bore, said barrel
having a pair of guide strips formed on a wall surface interior
to said bore and a reduced tubular outlet eccentrically disposed
on said conically shaped front portion and in open communication
with said bore;
a needle unit having a spindle shaped needle holder releasably
coupled to said tubular outlet and a cannulated needle affixed to
said needle holder to extend from a first end thereof, said needle
holder having a second end and a connecting stem extending therefrom,
said connecting portion having an inclined bottom surface and an
opening extending from said bottom surface with an arrowhead shaped
mortise formed in said opening and inclined with respect to an axis
of said needle;
a plunger slidingly disposed in said bore of said barrel, said
plunger having (a) a plunger head having an upper conical surface,
(b) an arrowhead shaped tenon eccentrically disposed on said plunger
head and extending from said upper conical surface thereof in aligned
relationship with said mortise of said connecting stem, (c) a sealing
ring circumscribing said plunger head, and (d) a supporting plate
disposed beneath said plunger head and supporting said sealing ring,
said supporting plate having a pair of guide notches formed therein
for respectively receiving said pair of guide strips therein, said
plunger being displaced toward said front portion of said barrel
to express a fluid from said barrel and engage said mortise with
said tenon, subsequent displacement of said plunger toward said
rear portion of said barrel thereby displaces said needle unit into
said bore of said barrel and said needle set being offset with respect
to said tubular outlet by cooperation between (i) said inclined
bottom surface of said connecting portion, (ii) said conical surface
of said plunger head, and (iii) said inclined mortise; and, a tubular
needle cap having a closed distal end for insert into said tubular
outlet subsequent to said needle unit being displaced into said
bore.
Safety syringe description
FIELD OF THE INVENTION
The present invention relates to a safety syringe for intravenous
injection with a guided plunger. More particularly, the present
invention is directed to a syringe where the needle and the needle
holder can be pulled into the barrel after use, to prevent an accidental
needle stick.
BACKGROUND OF THE INVENTION
In the past, needle stick injuries suffered by medical personnel
and others in the course of using intravenous syringes have presented
a serious problem. Serious problems such as hepatitis and AIDS may
be transmitted by such needle stick injuries, resulting in needless
suffering, and possibly even in death. Health care workers are susceptible
to accidental needle stick injuries while caring for AIDS or hepatitis
patients. Avoiding accidental needle sticks is very important for
health care workers.
The needle of a safety syringe is normally provided in a central
portion of the syringe, which is suitable for hypodermic or intramuscular
injection. However, such a syringe is not suitable for intravenous
injection of larger quantities of liquid medicine, filled in a large
size syringe. The needle should be eccentrically located with respect
to the center line of the syringe, for an ergonomic injection. Therefore,
an eccentrically-positioned needle is ergonomically better than
a centrally positioned needle of a syringe.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a safety syringe
for intravenous injection with a guided plunger, wherein the bottom
of a connecting stem, under the needle holder is formed with an
inclined surface so that the needle will be inclined after pulling
it into the barrel. Two guide strips are formed inside the barrel
toward two notches on a supporting plate, so that the plunger cannot
be rotated relative to the barrel and needle.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention can be better understood by detailed descriptions
of the following drawings, in which:
FIG. 1 is a partially sectioned illustration showing the present
invention;
FIG. 2 is an illustration showing the present invention at the
completion of an injection;
FIG. 2A is an enlarged sectional view of the bottom of the needle
holder of FIG. 2;
FIG. 3 is a sectional view of the present invention taken along
the section line A--A of FIG. 1;
FIG. 4 is a sectional view of the present invention taken along
the section line B--B of FIG. 1;
FIG. 5 illustrates the present invention with a needle retracted
into the syringe barrel;
FIG. 5A is an enlarged sectional view of the bottom of the needle
holder of FIG. 5;
FIG. 6 shows a blocking effect of an outwardly protruding needle
in the present invention; and,
FIG. 6A is an illustration showing the damage to a needle inside
the barrel when the plunger of the present invention is pushed forward.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIGS. 1 3 and 4 there is shown the present invention.
As shown in FIG. 1 the present invention includes a barrel 1 a
needle unit 2 and the plunger 3. The needle unit 2 has a cannulated
needle 21 a spindle-shaped needle holder 22 holding the rear portion
of the needle 21 therein. A connecting stem 23 extends downwardly
from the needle holder 22 the connecting stem having an inclined
bottom surface 230 thereat. An inclined arrowhead shaped mortise
231 is disposed in the connecting stem 23 and has a downward flared
opening 232 at the inclined bottom surface 230. An upwardly directed
through hole 233 (FIG. 2A) extends from a tip end of the arrowhead
shaped mortise 231 for leading a medicinal liquid into the cannula
of the needle 21. The barrel 1 has a reduced tubular outlet 11 disposed
on a conical front portion thereof, for mounting the needle holder
22 therein. An outward flange 12 is disposed at a bottom edge of
the rear end of the barrel, and two longitudinal guide strips 13
unsymmetrically disposed on opposite sides of the inner surface
of barrel 1. The plunger 3 comprises a plunger head 31 having an
arrowhead shaped tenon 311 eccentrically disposed on a conical top
surface thereof. A supporting plate 312 is disposed under the plunger
head 31 and has two guide notches 313 engaged with the guide strips
13. The plunger rod 310 has a cross-sectional contour and extends
from the plunger head 31 to an end plate 32. A sealing ring 33 is
inlaid into the periphery of the plunger head 31 and is supported
by the supporting plate 312.
Referring additionally to FIG. 2 there is shown the present invention
when the injection has finished. The plunger 3 is pushed forward
so that the arrowhead shaped tenon 311 is connected with the arrowhead
shaped mortise 231 of the connecting stem 23.
As shown in FIG. 3 two guide notches 313 formed in the supporting
plate 312 of the plunger 3 are engaged with the guide strips 13
inside of the barrel. When the plunger 3 is pushed forwardly by
a user's finger, the plunger 3 cannot be rotated so as to keep the
alignment between the arrowhead shaped tenon 311 and the mortise
231 for coupling therebetween through the flange opening 232 of
the connecting stem 23.
As shown in FIGS. 5 and 5A, when the plunger 3 is pulled backward,
the needle unit 2 is pulled into the barrel 1. The inclined bottom
surface of the connecting stem 23 the inclined arrowhead shaped
mortise 231 and the conical surface of the plunger head 31 make
the needle 21 incline to misalign the needle unit 2 with respect
to the reduced tubular outlet 11. According to the results of many
experiments, the needle 21 inclines mainly because of the inclined
bottom surface of the connecting stem.
Referring additionally to FIGS. 6 and 6A, when the plunger 3 is
subsequently pushed forward again the needle 21 cannot be forced
out of the barrel 1. A needle cap 14 is inverted and inserted into
the outlet 11 of the barrel 1 as shown in FIG. 5.
The above embodiments can be modified by any person skilled in
the art without departing the spirit and scope of the accompanying
claims.
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