Safety syringe abstract
A safety syringe has a needle hub detachably mounted at a front
end of the barrel and a plunger slidably received in the barrel
and having a retaining column extending out from the engaging flange
of the plunger. The needle hub has a pair of retaining plates with
a slot defined between the retaining plates. The retaining column
has a hook and a slanted face, such that when the retaining column
is securely clamped by the retaining plates and the needle hub is
forced to move inward the barrel, the needle hub is inclined with
respect to the barrel.
Safety syringe claims
What is claimed is:
1. A safety syringe comprising: a barrel with a through hole defined
in a front end of the barrel; a needle hub detachably engaged with
the barrel and having a needle securely engaged at a front end of
the needle hub, a flange formed on a rear end of the needle hub
and around an outer periphery of the needle hub and a pair of retaining
plates extending from the rear end of the needle hub and provided
with a slot defined between the pair of retaining plates, wherein
one of the pair of retaining plates defines therein an opening;
a plunger slidably received in the barrel and having ribs axially
extending in a longitudinal axis of the plunger, an engaging flange
formed at a front end of the plunger and a retaining column extending
out from the engaging flange to be detachably received between the
pair of retaining plates, the retaining column having a hook formed
to correspond to the opening of one of the retaining plates and
a slanted face oppositely formed to the hook, whereby when the hook
is received in the opening of one of the retaining plates and the
needle hub is forced to move into the barrel, the needle hub will
be inclined with respect to the barrel; and a seal securely mounted
around the retaining column so as to ensure a water tight engagement
between the plunger and the barrel.
2. The safety syringe as claimed in claim 1 wherein the retaining
column has a diameter larger than a diameter of the retaining plates
so as that when the retaining column is received between the retaining
plates, the retaining column is able to be securely clamped by the
retaining plates.
3. The safety syringe as claimed in claim 1 wherein the retaining
column comprises a neck extending out from the engaging flange and
a head formed on a free end of the neck and wherein the hook and
the slanted face are formed on the head.
4. The safety syringe as claimed in claim 2 wherein the retaining
column comprises a neck extending out from the engaging flange and
a head formed on a free end of the neck and wherein the hook and
the slanted face are formed on the head.
5. The safety syringe as claimed in claim 1 further comprising
a guiding device detachably mounted on the barrel to limit the rotation
of the plunger inside the barrel.
6. The safety syringe as claimed in claim 2 further comprising
a guiding device detachably mounted on the barrel to limit the rotation
of the plunger inside the barrel.
7. The safety syringe as claimed in claim 3 further comprising
a guiding device detachably mounted on the barrel to limit the rotation
of the plunger inside the barrel.
8. The safety syringe as claimed in claim 4 further comprising
a guiding device detachably mounted on the barrel to limit the rotation
of the plunger inside the barrel.
9. The safety syringe as claimed in claim 5 wherein the guiding
device has two guiding points each extending through the barrel
to slidably engage with one of the ribs such that rotation of the
plunger inside the barrel is prevented.
10. The safety syringe as claimed in claim 6 wherein the guiding
device has two guiding points each extending through the barrel
to slidably engage with one of the ribs such that rotation of the
plunger inside the barrel is prevented.
11. The safety syringe as claimed in claim 7 wherein the guiding
device has two guiding points each extending through the barrel
to slidably engage with one of the ribs such that rotation of the
plunger inside the barrel is prevented.
12. The safety syringe as claimed in claim 8 wherein the guiding
device has two guiding points each extending through the barrel
to slidably engage with one of the ribs such that rotation of the
plunger inside the barrel is prevented.
13. The safety syringe as claimed in claim 3 wherein the seal
is received between the engaging flange and the head and has a space
defined to receive therein the head.
14. The safety syringe as claimed in claim 5 wherein the seal
is received between the engaging flange and the head and has a space
defined to receive therein the head.
15. The safety syringe as claimed in claim 9 wherein the seal
is received between the engaging flange and the head and has a space
defined to receive therein the head.
16. The safety syringe as claimed in claim 13 wherein the seal
has a hole defined in a bottom of the seal to allow the extension
of the head.
17. The safety syringe as claimed in claim 14 wherein the seal
has a hole defined in a bottom of the seal to allow the extension
of the head.
18. The safety syringe as claimed in claim 15 wherein the seal
has a hole defined in a bottom of the seal to allow the extension
of the head.
Safety syringe description
BACKGROUND OF THF INVENTION
1. Field of the Invention
The present invention relates to a safety syringe, and more particularly
to a safety syringe having a plunger with a hook formed on a distal
end of the plunger and a needle hub with a pair of retaining plates
one of which has an opening defined to correspond to the hook, so
that after the hook extends through the opening and securely engages
with a periphery of the opening, the needle hub is able to be driven
by the plunger into the barrel.
2. Description of Related Art
With reference to FIG. 9 a conventional safety syringe has a needle
hub (70) with a bottom (71) defining therein a Y-shaped channel
(72) and a plunger (80) with an arrow head (81) formed on a distal
end of the plunger (80) to correspond to the Y-shaped channel (72).
It is to be noted that the Y-shaped channel (72) is inclined with
respect to an imaginary longitudinal axis of the syringe, such that
when the arrow head (81) is received in the Y-shaped channel (72)
and the plunger (80) is moving away from the needle hub (70), the
needle hub (70) will be driven backward into the barrel (82). Because
the Y-shaped channel (72) is inclined relative to the imaginary
longitudinal axis of the syringe, after the needle hub (70) is completely
pulled back in the barrel (82), the needle (73) together with the
needle hub (70) is slantedly received in the barrel (82), such that
the needle (73) can not be used again. However, when a solution
is received in the barrel (82) and the plunger (80) is pushing forward
to the needle hub (70), the approaching of the arrow head (81) to
the Y-shaped channel (72) stops the flow of the solution out of
the needle (73). The pressure of the remaining solution within the
barrel (82) also stops the continuous movement of the arrow head
(81) to the Y-shaped channel (72), such that the arrow head (81)
can not be received in the Y-shaped channel (72) when in application.
To overcome the shortcomings, the present invention tends to provide
an improved safety syringe to mitigate and obviate the aforementioned
problems.
SUMMARY OF THE INVENTION
The primary objective of the present invention is to provide a
safety syringe having a plunger with a head integrally formed on
a distal end of the plunger by means of a neck, wherein the head
has a hook formed on a sidewall of the head and a slanted face formed
oppositely to the hook and a needle hub with a pair of retaining
plates one of which has an opening defined to correspond to the
hook and a slit defined between the two retaining plates. When the
hook is approaching the opening, the remaining solution inside the
barrel can still flow through the slit and out of the needle.
Another objective of the present invention is to provide a positioning
device to secure the alignment of the hook to the opening during
the movement of the plunger, so that a user will not have to rotate
the plunger to align the hook to the opening after use.
Other objects, 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
FIG. 1 is a perspective view of the safety syringe of the present
invention;
FIG. 2 is an exploded perspective view of the safety syringe of
FIG. 1;
FIG. 3 is a cross sectional view showing a status before the engagement
of the hook and the opening of the retaining plate;
FIG. 4 is a cross sectional view taken along the line 4--4 of FIG.
1 wherein the hook is received in the opening of the retaining
plate;
FIG. 5 is a schematic cross sectional view of the initial disengagement
of th needle hub to the front end of the barrel;
FIG. 6 is a schematic cross sectional view showing that the needle
hub is completely disengaged from the front end of the barrel;
FIG. 7 is a schematic cross sectional view showing the abutment
of the needle to an inner face of the barrel;
FIG. 8 is a cross sectional view taken from the line 8--8 of FIG.
1; and
FIG. 9 is a cross sectional view showing a conventional syringe.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
With reference to FIG. 1 a safety syringe in accordance with the
present invention has a barrel (10), a needle hub (20) and a plunger
(30).
With reference to FIG. 2 and still taking FIG. 1 for reference,
the barrel (10) has a through hole (12) defined in a front end of
the barrel (10), a finger flange (16) formed on a rear end and around
an outer periphery of the barrel (10) and a pair of apertures (18)
defined in the outer periphery of the barrel (10). The needle hub
(20) has a needle (22), a flange (26) and a pair of retaining plates
(28). The needle (22) is securely engaged with the needle hub (20)
and extends out of the needle hub (20). The flange (26) is integrally
formed on a distal end of the needle hub (20) opposite to the needle
(22). One of the retaining plates (28) has an opening (280) defined
in a side face of the retaining plate (28) and a slot (282) is defined
between the two retaining plates (28). The plunger (30) has ribs
(34) axially extending from an engaging flange (38). A retaining
column (36) extends oppositely to the ribs (34) by a neck (360)
bridging between the engaging flange (38) and the retaining column
(36). The column (36) has a head (362) having a diameter larger
than the diameter of the neck (360) and a hook (364) formed on a
sidewall of the head (362). The head (362) further has a slanted
sidewall (366) oppositely formed to the hook (364). A rubber-made
seal (40) has a closed end with a hole (44) and an open end defining
therein a space (42). The hole (44) is defined to correspond to
the retaining column (36) such that the retaining column (36) is
able to extend through the hole (44) and the seal (40) is retained
between the head (362) and the engaging flange (38), as shown in
FIG. 2. Furthermore, a guiding device (50) has two guiding points
(52) extending toward each other. The positioning points (52) correspond
to the apertures (18) in the outer periphery of the barrel (10).
With reference to FIG. 3 when the syringe of the present invention
is assembled, as previously described, the seal (40) is received
between the engaging flange (38) and the head (362) with the head
(362) together with the hook (364) extending through the hole (44)
of the seal (40). The needle hub (20) is detachably engaged with
the barrel (10) with the needle (22) extending through the through
hole (12) of the barrel (10).
With reference to FIG. 4 when a solution is received in the barrel
(10) and the plunger (30) is pushed toward the needle hub (20),
the solution inside the barrel (10) is able to flow through the
slot (282) between the two retaining plates (28) and into the needle
(22) even after the head (362) extends between the two retaining
plates (28) with the hook (364) extending outward from the opening
(280) of the retaining plate (28).
With reference to FIGS. 5 6 and 7 after the hook (364) is received
in the opening (280) of one of the retaining plates (28), because
the diameter of the head (362) is larger than the diameter of the
slot (282) between the two retaining plates (28), the head (362)
will force the retaining plates (28) to expand thereby allowing
one of the retaining plates (28) to securely abut the slanted face
(366) of the head (362). Accordingly, after the needle hub (20)
is pulled backward into the barrel (10), the abutment of the retaining
plate (28) to the slanted face (366) of the head (362) causes the
needle hub (20) to incline relative to the barrel (10) after the
disengagement of the needle hub (20) with the front end of the barrel
(10). Thereafter when the plunger (30) pushes the needle hub (20)
toward the front end of the barrel (10) again, due to the inclination
of the needle hub (20), the front end of the needle (22) will abut
an inner face of the barrel (10). Thus, safety of after using the
syringe is accomplished.
Furthermore, with reference to FIG. 8 in order to have the alignment
between the hook (364) and the opening (280), the guiding device
(50) is mounted on the outer periphery of the barrel (10) with the
guiding points (52) received in the corresponding apertures (18)
of the barrel (10). After the extension of the guiding points (52)
into the apertures (118), the guiding points (52) are slidably engaged
with two of the ribs (34), which guides the movement of the plunger
(30) inside the barrel (10) to ensure the alignment of the hook
(364) to the opening (280). Naturally, a user may still use this
syringe without the guiding device (50). The user may rotate the
plunger (30) inside the barrel (10) to align the hook (364) to the
opening (280) after injection.
It is concluded that the syringe of the present invention has the
advantages such as: Easy pushing of the plunger; Because the solution
inside the barrel (10) is able to flow through the slot (282) even
after the head (362) is received between the pair of retaining plates
(28), the plunger (30) has no resistance to approach the needle
hub (20).
Accurate alignment between the hook (364) and the opening (280);
With the limitation of the guiding points (52) of the guiding device
(50), the movement and potential rotation of the plunger (30) are
guided. Ensured safety; Due to the slanted face (366) on the head
(362), the needle hub (20) is inclined when pulled backward into
the barrel (10), such that a reuse of the needle hub (20) together
with the needle (22) is prevented.
It is to be understood, however, that even though numerous characteristics
and advantages of the present invention have been set forth in the
foregoing description, together with details of the structure and
function of the invention, the disclosure is illustrative only,
and changes may be made in detail, especially in matters of shape,
size, and arrangement of parts within the principles of the invention
to the full extent indicated by the broad general meaning of the
terms in which the appended claims are expressed. |