Safety syringe abstract
A disposable safety syringe has a barrel, a connector assembled
at a front end of the barrel, a needle assembly assembled onto the
connector, and a plunger extendable into the barrel. The plunger
has a connecting head such that the connecting head is able to be
securely connected with the connector after an injection of the
syringe. Therefore, the needle assembly is able to be pulled by
the plunger to fully retract into the barrel and the syringe is
then safe to discard without the risk of scratching someone.
Safety syringe claims
What is claimed is:
1. A disposable safety syringe comprising: a hollow barrel having
a front open end and a rear open end; a plunger extendable into
the barrel from the rear open end, the plunger having a front end
to extend into the barrel and an upper sealing ring securely mounted
around the front end; a connecting head formed at the front end
of the plunger; the connecting head defining a groove; a hollow
connector assembled in the front open end of the plunger, the hollow
connector having a positioning portion and a tube portion; a lower
sealing ring securely mounted around the positioning portion of
the hollow connector, the lower sealing ring defining a bore extending
through the lower sealing ring and having a flange extending into
the bore to be received in the groove defined in the connecting
head; a needle assembly mounted onto the connector and having a
needle hub and a needle extending out from the needle hub, the needle
hub defining a receiving hole configured to allow the tube portion
to be force fitted inside the receiving hole, whereby after an injection
process using the disposable safety syringe is completed, the connecting
head and the lower sealing ring are able to be securely connected
together by securely receiving the flange inside the groove, and
therefore the needle assembly is able to be fully retracted inside
the barrel by pulling the plunger such that the needle is safely
received inside the barrel to prevent accidentally scratching someone.
2. The disposable safety syringe as claimed in claim 1 wherein
the flange of the lower sealing ring is formed as an annular flange.
3. The disposable safety syringe as claimed in claim 2 wherein
the groove defined in the connecting head is defined as an annular
groove to correspond to the annular flange.
4. The disposable safety syringe as claimed in claim 1 wherein
the flange is inclined toward a free end of the connecting head
and the groove is defined corresponding to an inclined configuration
of the flange to ensure the flange to be securely received in the
groove.
5. The disposable safety syringe as claimed in claim 3 wherein
the annular flange is inclined toward a free end of the connecting
head and extends into the bore of the lower sealing ring, the annular
groove is defined corresponding to an inclined configuration of
the annular flange to ensure the annular flange to be securely received
in the annular groove.
Safety syringe description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a syringe and more particularly
to a disposable safety syringe. The syringe has a retractable needle
to be pulled inside a barrel by a plunger after use, whereby accidental
pricking is prevented.
[0003] 2. Description of Related Art
[0004] Healthcare workers routinely have the risk of contracting
communicable diseases through accidental exposure to contaminated
medical waste products. One of the largest exposure risks to healthcare
workers and handlers of the medical waste products is from accidental
pricking from used syringe needles. It is reported that odds of
a healthcare worker contracting human immunodeficiency virus (HIV)
alone through accidental pricking are one in 300. The odds of healthcare
workers contracting other serious diseases are even greater.
[0005] Therefore a current disposable syringe having a retractable
needle is designed to solve the accidental pricking problem. The
disposable syringe typically has a retractable needle which is able
to be captured by a plunger. By pulling the plunger, the needle
is fully retracted inside a barrel, and the contaminated syringe
is able to be discarded safely without the risk of pricking someone.
[0006] However, the disposable syringe having the retractable needle
is able to solve the accidental pricking problem only under an ideal
situation. Further problems may still arise in practical use, for
example, when retracting the needle, the connection between the
needle and the plunger is not secure enough, and may undesirably
detach before the needle is fully retracted inside the barrel. The
undesirable detachment may cause a health risk to the user due to
the chance of accidental pricking. Furthermore, before an injection
can be given, air bubbles in the fluid contained in the syringe
must be evacuated. For conventional syringes, the user usually has
to point the needle upward and flick the barrel to help the air
bubbles to evacuate. This procedure is not convenient and needs
to be improved.
[0007] Accordingly, the present invention tends to provide a disposable
safety syringe to mitigate or obviate the aforementioned problems.
SUMMARY OF THE INVENTION
[0008] An objective of the present invention is to provide a disposable
safety syringe to prevent accidental pricking, scratching or other
harmful exposure to healthcare workers. The syringe has a barrel,
a connector assembled at a front end of the barrel, a needle assembly
fitted onto the connector, and a plunger extendable into the barrel.
The plunger has a connecting head such that the connecting head
is able to capture the connector after an injection process is completed.
Therefore, the needle assembly is able to be pulled by the plunger
to fully retract into the barrel and the syringe is then safe to
discard without the risk of scratching someone.
[0009] Another objective of the present invention is to provide
a disposable safety syringe having the structure as mentioned in
the previous objective, wherein the connection between the connector
and the connecting head of the plunger is secure and undesirable
detachment of the connector and the connecting head during retraction
of the needle assembly is prevented.
[0010] Another objective of the present invention is to provide
a disposable safety syringe specially designed such that air bubbles
in the fluid contained in the barrel before an injection are easily
ejected prior to the injection process.
[0011] Other objectives, advantages and novel features of the invention
will become more apparent from the following detailed description
when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is an exploded, perspective view of a disposable
safety syringe in accordance with the present invention;
[0013] FIG. 2 is a perspective view of the syringe in assembly;
[0014] FIG. 3 is a cross-sectional view of the syringe taken along
line 3-3 in FIG. 2;
[0015] FIG. 4 is a partially enlarged, cross-sectional view showing
a front portion of the syringe, wherein a connector head securely
captures a connector;
[0016] FIG. 5 is a cross-sectional view of the syringe after use,
wherein a needle assembly is retracted into a barrel and a plunger
is broken off for convenient discarding; and
[0017] FIG. 6 is a partially enlarged, cross-sectional view showing
the connector and the connecting head.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0018] With reference to FIGS. 1 and 2 a disposable safety syringe
in accordance with the present invention, which includes a barrel
(10), a plunger (20), a connecting head (28), an upper sealing ring
(30), a connector (40), a needle assembly (50), and a lower sealing
ring (60).
[0019] The barrel (10) is a hollow cylinder having a front open
end and a rear open end. A finger flange (100) is integrally formed
at and extending outwardly from the rear open end. Multiple restricting
protuberances (102) are formed on an inner surface of the barrel
(10) close to the rear open end. Multiple retaining protuberances
(104) are formed on the inner surface of the barrel (10) and close
to the front open end.
[0020] With reference to FIGS. 1 and 6 the plunger (20) is extendable
into the barrel (10) and includes multiple elongated body pieces
(22), a thumb pad formed at a rear end of the plunger (20) and a
piston (25) formed at a front end of the plunger (20). Each one
of the body pieces (22) is provided with a fracture line (24) defined
near a front end of the plunger (20) so as allow the body pieces
(22) to be easily broken off and thus separated from the piston
(25) after completion of the injection process. The piston (25)
comprises a retaining portion (26) for the upper sealing ring (30)
to be mounted around. A connecting head (28) having a conical configuration
is integrally formed with the retaining portion (26). An annular
groove (29) is defined in the connecting head (28) and adjacent
to the retaining portion (26). More specifically the annular groove
(29) is defined by an abutting surface (292) and a back surface
(294), wherein the back surface (294) is inclined toward a free
end of the connecting head (28).
[0021] The connector (40) has a positioning portion (42) for the
lower sealing ring (60) to mount around, a tube portion (44) for
the needle assembly (50) to mount onto, and a disk portion (46)
formed between the positioning portion (42) and the tube portion
(44). A passage (404) is longitudinally defined through the connector
(40). An annular slit (462) is defined around the disk portion (46)
to receive the restricting protuberances (102) and thereby connects
the connector (40) to the front opening end of the barrel (10).
[0022] The lower sealing ring (60) to be mounted around the positioning
portion (42) of the connector (40) has a top surface (602), a bottom
surface (603), and a bore (604) defined through the lower sealing
ring (60) from the top surface (602) to the bottom surface (603).
An annular flange (606) having a configuration corresponding to
the annular groove (26) of the connecting head (28) integrally extends
from the top surface (602) and into the bore (604) to be received
in the annular groove (26) defined in the connecting head (28).
[0023] The needle assembly (50) to be mounted onto the connector
(40) has a hollow needle (52) extending out from a needle hub (54),
wherein the hollow needle (52) and the needle hub (54) are securely
connected together. A receiving hole (56) configured for receiving
the tube portion (44) of the connector (40) is longitudinally defined
in the needle hub (54).
[0024] With reference to FIGS. 2 and 3 when assembling the disposable
safety syringe, the lower sealing ring (60) is mounted around the
positioning portion (42) of the connector (40), wherein the bore
(604) defined in the lower sealing ring (60) communicates with the
passage (404) defined in the connector (40). Then the connector
(40) is assembled into the front open end of the barrel (10) by
receiving the retaining protuberances (104) of the barrel (10) into
the annular slit (462) of the disk portion (46) of the connector
(40). Next the upper sealing ring (30) is mounted around the retaining
portion (26) of the plunger (20), and the plunger (20) extends the
connecting head (28) into the barrel (10) via the rear opening end
of the barrel (10). Proper force is required to push the connecting
head (28) to slide over the retaining protuberances (104) formed
close to the rear open end of the barrel (10). Finally the needle
assembly (50) is assembled onto the connector (40) by force fitting
the tube portion (44) of the connector (40) into the receiving hole
(56) defined in the needle assembly (50). At this moment, the syringe
is ready to be used. The procedure of performing an injection using
the syringe is same as those of the prior art syringes, and owing
to that syringes are widely known medical instruments and have been
used for years, therefore excessive description on the injection
procedure of the syringe is omitted. However, it is noted that due
to the conical configuration of the connecting head (28) and that
the back surface (294) is inclined toward a free end of the connecting
head (28), air bubbles in the fluid contained in the barrel (10)
are easily ejected by pointing the needle (52) upward and pushing
the plunger (20) a little further into the barrel (10). The filliping
against the barrel (10) to help the air bubbles be ejected as usually
required before use of a conventional syringe is not necessary.
[0025] With reference to FIG. 4 after use of the syringe in accordance
with the present invention, the plunger (20) is pushed further into
the barrel (10) so as to allow the connecting head (28) to be securely
connected with the connector (40) by securely receiving the annular
flange (606) of the upper sealing ring (60) in the corresponding
annular groove (29) defined in the connecting head (28). The plunger
(20) is then pulled so as to pull the connector (40) together with
the needle assembly (50) to retract into the barrel (10). With reference
to FIG. 5 the needle assembly (50) is pulled until the needle (52)
is fully retracted inside the barrel (10) and the restricting protuberances
(102) (better seen in FIG. 2) prevent the connecting head (28) from
escaping from the rear open end of the barrel (10). The piston (25)
is separated by the body pieces (22) of the plunger (20) being broken
off along the fracture lines (24). Therefore, the contaminated needle
(52) is received inside the barrel (10) and the used syringe is
able to be discarded safely without accidentally scratching someone.
[0026] From the above description, it is noted that the invention
has the following advantages:
[0027] 1. The connection between the connecting head (28) and the
lower sealing ring (60) is secure and undesirable detachment during
the retraction of the needle assembly (50) is prevented.
[0028] 2. The connecting head (28) and the lower sealing ring (60)
have specially designed configurations such that the air bubbles
are easily ejected from the barrel (10) before an injection is given.
[0029] 3. The structure of the syringe is simple and suitable for
mass production.
[0030] While this invention has been particularly shown and described
with references to the preferred embodiment thereof, it will be
understood by those skilled in the art that various changes in form
and details may be made therein without departing from the scope
of the invention encompassed by the appended claims. |