Safety syringe abstract
A retractable hypodermic safety syringe device is provided for
encapsulating a needle after use to prevent accidental needlesticks.
The retractable syringe device includes a syringe barrel having
one or more locking tabs for securing a needle carrier. A hypodermic
needle attached to the needle carrier. A plunger having a piston
slideably mounted within the syringe body. Locking fingers on the
needle carrier for receiving the plunger.
Safety syringe claims
We claim:
1. A retractable hypodermic safety syringe device comprising: a
syringe barrel with a hollow interior and open on each end, said
syringe barrel having a distal end with an inwardly protruding ramp;
a locking tab attached near said distal end of said syringe barrel,
said locking tab including a lip protruding into said hollow interior;
a needle carrier for securing a hypodermic needle, said carrier
including a notch for receiving said lip and a surface for contacting
said ramp; a plunger sideably mounted within said syringe barrel;
a piston secured to an end of said plunger, said piston having a
snap extending therefrom; and locking fingers on said needle carrier
for receiving said snap, said fingers extending away from said hollow
interior of said syringe barrel.
2. The retractable hypodermic safety syringe device according to
claim 1 wherein said locking tab and said syringe barrel are molded
together.
3. The retractable hypodermic safety syringe device according to
claim 1 further comprising a seal secured to said plunger for preventing
fluid from leaking from said syringe barrel.
4. The retractable hypodermic safety syringe device according to
claim 1 wherein said plunger includes a notch for fracturing said
plunger.
5. A method for retracting a hypodermic needle into a syringe barrel,
the method comprising the steps of: locking a needle carrier within
the syringe barrel by extending a tab from said syringe barrel to
a notch on said needle carrier; securing a hypodermic needle to
said needle carrier; pushing a slideable plunger containing a snap
within the syringe barrel so as to engage said snap with fingers
on said carrier and to discharge a fluid within the syringe barrel;
and retracting said plunger with said needle carrier such that said
hypodermic needle is completely encapsulated by the syringe barrel.
6. The method for retracting a hypodermic needle according to claim
5 further comprising the step of breaking said plunger at a notch
on said plunger.
Safety syringe description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Not applicable.
STATEMENTS REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
REFERENCE TO A MICROFICHE APPENDIX
[0003] Not applicable.
BACKGROUND OF THE INVENTION
[0004] 1. Field of the Invention
[0005] The present invention relates to a retractable hypodermic
safety syringe. In particular, the present invention relates to
a safety syringe for completely encapsulating a needle after use
to prevent accidental needlesticks or reuse of the needle.
[0006] 2. Description of the Related Art
[0007] Healthcare workers in the United States suffer over a half
million needlesticks each year. From these needlestick injuries
healthcare workers contract HIV, become infected with hepatitis
C and hepatitis B, and acquire such infectious diseases as tuberculosis,
syphilis, malaria, herpes, diphtheria, gonorrhea, typhus and Rocky
Mountain spotted fever.
[0008] Healthcare workers worldwide are concerned about accidental
needlesticks resulting in life-threatening infections. Often, healthcare
workers become patients after being injured by contaminated needles.
These healthcare workers contract potentially deadly infections
from needlestick injuries that are largely preventable.
[0009] Many methods and devices have been created to reduce accidental
needlesticks by contaminated needles. An example of such a device
is shown in U.S. Pat. No. 4790822. This patent discloses a retractable
hypodermic safety syringe that retracts the used needle into the
barrel of the syringe after use. A disadvantage of this design,
however, was the expense and the difficulty of manufacture related
to the molded internal parts of the syringe barrel, such as shoulders.
Another disadvantage included the close tolerances [on what parts?]
Another disadvantage of this device was the inability to evacuate
the entire contents of the cavity.
BRIEF SUMMARY OF THE INVENTION
[0010] Briefly, the present invention provides an improved retractable
hypodermic safety syringe that allows the needle to be retracted
into the syringe cylinder after an injection has been given without
the practitioner contacting the needle, thereby avoiding contamination
by infectious agents. The retractable syringe device is simple and
convenient to use. Additionally, the retractable syringe device
is easy to manufacture because there are few internal parts molded
to the inside of the syringe barrel. Moreover, the device includes
locking and releasing tabs that provide a positive locking mechanism
without the need for close tolerance snap fittings. Further, the
retractable syringe device provides a means for evacuating the entire
contents of the syringe barrel and needle carrier cavity.
[0011] The retractable syringe device includes a syringe cylinder,
and a needle carrier for securing a hypodermic needle. A plunger
snap coupling engages the needle carrier, allowing the needle carrier
to be slid into the cylinder as the plunger is retracted to a locked
position. As this snap coupling occurs, further pressure on the
plunger also releases a set of positive locking tabs that secure
the needle carrier to the syringe cylinder. This set of locking
tabs insures that the needle carrier will not become dislodged during
normal operation of loading and injecting medications.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0012] A better understanding of the present invention can be obtained
when the following detailed description of the preferred embodiment
is considered in conjunction with the following drawings, in which:
[0013] FIG. 1 is an elevational view of the retractable hypodermic
safety syringe of the present invention;
[0014] FIG. 2 is a side elevational view of the device in FIG.
1;
[0015] FIG. 3 is a side elevational view, partially in section,
as viewed along line 3-3 of FIG. 2;
[0016] FIG. 4 is a side elevational view, partially in section,
of the device in FIG. 1;
[0017] FIG. 5 is an expanded side elevational view, partially in
section, of a portion of the device within circle 5 of FIG. 4;
[0018] FIG. 6 is a side elevational view, partially in section,
of the device in FIG. 1;
[0019] FIG. 7 is an expanded side elevational view, partially in
section, of a portion of the device within circle 7 of FIG. 6;
[0020] FIG. 8 is a side elevational view, partially in section,
of the device in FIG. 1;
[0021] FIG. 9 is a side elevational view, partially in section,
as viewed along line 9-9 of FIG. 8;
[0022] FIG. 10 is an expanded side elevational view, partially
in section, of a portion of the device within circle 10 of FIG.
8;
[0023] FIG. 11 is a side elevational view of the device in FIG.
1;
[0024] FIG. 12 is a side elevational view, partially in section,
of the device in FIG. 11; and
[0025] FIG. 13 is an expanded side elevational view, partially
in section, of a portion of the device within circle 13 of FIG.
12.
DETAILED DESCRIPTION OF THE INVENTION
[0026] A retractable hypodermic safety syringe device 30 according
to the present invention is shown in FIG. 1 prior to use. The retractable
syringe device 30 includes a syringe barrel or body 1 for holding
injectable fluids. A plunger 14 is inserted at one end of the syringe
barrel 1. The opposite end of the syringe barrel 1 includes a needle
carrier 4 which receives a hypodermic needle 13 for injecting patients.
[0027] The syringe barrel 1 includes locking tabs 3 for securing
the needle carrier 4 to the syringe body 1 prior to retraction of
the needle 13 into the syringe body. In the preferred embodiment,
the locking tabs 3 are molded into the wall of the syringe body
1. A notch 21 on the needle carrier 4 receives a lip portion 32
of the locking tabs 13 and secures the needle carrier 4 within the
syringe barrel 1. The syringe barrel 1 also includes a lower body
portion 23 for abutting the needle carrier 4 on a front surface
7. The combination of the locking tabs 3 and the lower body 23 works
to retain the needle carrier 4 within the syringe barrel 1 during
loading of the syringe and injecting of the fluid into a patient.
[0028] Referring to FIGS. 2 and 3 the retractable syringe device
30 is shown with the plunger 14 in the fully retracted position.
The plunger 14 includes a piston 15 and a plunger snap 16 extending
from the piston for engaging the needle carrier 4. Outward travel
of the plunger 14 within the syringe barrel 1 is limited by a plunger
seal interference ring 26 located on the interior of the syringe
barrel 1. Typically, the syringe barrel is made from a mold which
includes relief for the interference ring 26. A plunger seal 24
secured to the plunger 14 includes a plunger wiping ring 25 which
contacts the interference ring 26 when the plunger 14 is extracted
during loading of the syringe barrel.
[0029] The needle carrier 4 includes the notch 21 for receiving
the locking tabs 3 to secure the needle carrier 4 to the syringe
barrel 1. The needle carrier 4 also includes a carrier seal 5 sized
to be in an interference fit with the inner wall on the syringe
body 1. The carrier seal 5 prevents fluid from leaking out of the
syringe barrel 1. Fingers 9 for receiving the plunger snap 16 extend
from a cavity 6 of the needle carrier 4. The needle 13 includes
a conical fitting 12 which is pressed and sealed onto a carrier
conical fitting 8.
[0030] Referring to FIGS. 4 and 5 the plunger 14 is pushed into
the syringe barrel 1 by means of a plunger grip 20 and a syringe
body grip 2 until resistance is felt due to the contact of the snap
16 with the locking fingers 9. The resistance occurs when the load
is ejected from the syringe and when the syringe is being loaded
with fluid. Upon feeling the resistance, the user appreciates that
the plunger snap 16 is almost engaged by the FIG. 9 of the needle
carrier 4. At this point, the plunger piston 15 is moved into the
geometrically matching cavity 6 which purges the load (or air,
if in fill mode) from the cavity 6.
[0031] As shown in FIGS. 6 and 7 when the injection is finished
and it is desired to set the needle 13 to the safe position (as
shown in FIG. 12) the user must apply sufficient pressure to the
plunger grip 20 to spring the carrier locking fingers 9 open and
allow the plunger snap 16 to pass through and lock behind the carrier
locking fingers 9. As shown in FIGS. 8-10 as the user continues
to apply pressure to the plunger grip 20 a plunger push surface
17 contacts a rear surface 11 of the needle carrier 4 until a plunger
stop 19 on the plunger 14 contacts the syringe body grip 2.
[0032] At this point, the needle carrier 4 has moved sufficiently
to allow the locking tabs 3 to release from the notch 10 of the
needle carrier 4. The locking tabs 3 are sprung to the position
shown in FIG. 10 returning to their normal "as molded,"
pre-loaded position. To insure the locking tabs 3 are ejected from
the notch 10 a carrier tab ejection surface 21 on the needle carrier
4 is used to push the locking tabs 3 outward as the needle carrier
4 is pulled back by the plunger 14.
[0033] For the device to work properly, the force to slide the
needle carrier 4 and release the locking tabs 3 must be greater
than the snap mechanism comprised of the plunger snap 16 and the
fingers 9. This insures that the locking tabs 3 do not disengage
until the plunger grip 20 has had sufficient force applied to cause
the snap engagement of the plunger snap 16 and fingers 9. The force
required for releasing the tabs 3 is much greater than what is felt
in normal filling and dispensing of the load. As a result, the locking
tabs 3 will stay engaged until the user desires release of the needle
carrier 4.
[0034] Referring to FIGS. 9 and 10 as the needle carrier 4 is
pushed by the plunger 14 a carrier front surface 7 contacts a syringe
body ramp 22 on the lower body portion 23 which causes the lower
syringe body 23 to flex outward. The force required to cause the
flex and allow travel of the needle carrier 4 is greater than the
force required to engage the plunger snap 16 and the carrier locking
fingers 9 thereby insuring the locking tabs 3 are held in place
in the notch 10 until after this snap occurs. The deflection force
of the lower syringe body 23 as shown in FIG. 9 is applied by
the distortion strain of the circular cross section geometry, as
relieved by a syringe body slot 27.
[0035] Referring to FIGS. 11-13 with locking tabs 3 disengaged,
the plunger 14 can now be pulled to the fully retracted position
by the plunger grip 20 until the plunger wiping ring 25 passes the
plunger seal interference ring 26 indicating to the user the end
of travel of the plunger 14. At this point the plunger 14 can be
broken at a plunger break-off notch 18 leaving the plunger piston
15 plunger seal 24 needle carrier 4 and needle 13 inside the
syringe body 1. This assembly is held in position by the plunger
wiping ring 25 and the plunger seal interference ring 26. The needle
13 is recessed a distance 28 to protect the user from needlesticks.
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