Safety syringe abstract
A safety syringe has a hollow shield with a plunger opening on
one end and a needle opening on the other end. At least one locking
lug is mounted at the plunger opening. The syringe also has a lumen
that is telescopically mounted at least partially within the shield.
The lumen has a catch for engaging the locking lug. A needle attached
to the lumen is aligned with the needle opening of the shield. An
urging means is mounted in the shield to urge the lumen and to retract
the needle into the shield. A plunger has an inner end slidably
mounted in the lumen and an outer end mounted through the plunger
opening. The outer end of the plunger has an extension for engaging
and deflecting the locking lug to release the catch, which allows
the urging means to retract the needle into the shield.
Safety syringe claims
I claim:
1. A safety syringe comprising:
an outer hollow shield having a plunger opening, a needle opening,
and at least one locking lug mounted at said plunger opening;
a lumen telescopically mounted at least partially within said shield
and having a catch for engaging said locking lug;
a needle attached to said lumen and aligned with said needle opening
in said shield;
urging means mounted in said shield for urging said lumen and retracting
said needle into said shield;
a plunger having an inner end slidably mounted in said lumen and
an outer end mounted through said plunger opening, said outer end
of said plunger having an extension for engaging and deflecting
said locking lug without entering said lumen to release said catch,
so that said urging means can retract said needle into said shield.
2. The safety syringe of claim 1 wherein said shield includes at
least one finger support projecting from said shield.
3. The safety syringe of claim 2 comprising a locking means mounted
on said lumen for locking said needle in said shield upon retraction
of said needle into said shield, wherein the locking means comprises:
a lock mounted on said lumen for locking on said locking lug; and
a stop mounted on said lumen and spaced from said lock, said stop
being arranged to abut said locking lug when said catch is released.
4. The safety syringe of claim 3 wherein said lock has a wedging
surface for spreading said locking lugs.
5. The safety syringe of claim 4 wherein said stop has an outside
diameter slightly smaller than the inside diameter of said shield
and wherein said lock is separated from said stop by approximately
the thickness of said locking lugs.
6. The safety syringe of claim 5 wherein said urging means comprises
a compression spring mounted between said stop and said shield.
7. The safety syringe of claim 2 wherein said extension on said
plunger is disc-shaped and has a beveled edge for engaging and deflecting
said locking lug.
8. The safety syringe of claim 7 wherein said locking lug comprises
a plurality of rectangular members mounted at said plunger opening
for engaging said catch on said lumen, said rectangular members
being spreadable when engaged by said beveled edges of said extension.
9. The safety syringe of claim 8 further comprising:
a plurality of cantilevered supports mounted at said plunger opening,
said rectangular members being separately mounted on corresponding
ones of said cantilevered supports.
10. The safety syringe of claim 9 wherein said finger support
includes a first support and a second support oppositely projecting
from said shield.
11. The safety syringe of claim 2 wherein said locking lug has
a slanted face positioned to engage and be deflected by said extension.
12. A safety syringe comprising:
an outer hollow shield having a plunger opening, a needle opening,
and a plurality of locking lugs mounted at said plunger opening;
a lumen telescopically mounted at least partially within said shield
and having a catch for engaging said locking lugs;
a needle attached to said lumen and aligned with said needle opening
in said shield;
a lock encircling said lumen;
a stop encircling said lumen and spaced between said needle and
said lock;
a compression spring mounted between said lock and said shield;
and
a plunger having an inner end slidably mounted in said lumen and
an outer end mounted through said plunger opening, said outer end
of said plunger having an extension for engaging and deflecting
said locking lugs to release said catch, so that said spring can
retract said needle into said shield.
13. A safety syringe comprising:
an outer hollow shield having a plunger opening, a needle opening,
and at least one locking lug mounted at said plunger opening;
a lumen telescopically mounted at least partially within said shield
and having a catch for engaging said locking lug;
a needle attached to said lumen and aligned with said needle opening
in said shield;
urging means mounted in said shield for urging said lumen and retracting
said needle into said shield;
a plunger having an inner end slidably mounted in said lumen and
an outer end mounted through said plunger opening, said outer end
of said plunger having an extension for engaging and deflecting
said locking lug to release said catch, so that said urging means
can retract said needle into said shield; and
a locking means mounted on said lumen for locking said needle in
said shield upon retraction of said needle into said shield, said
locking means comprising:
a lock mounted on said lumen for locking on said locking lug; and
a stop mounted on said lumen and spaced from said lock, said stop
being arranged to abut said locking lug when said catch is released.
Safety syringe description
BACKGROUND OF THE INVENTION
The present invention relates to a syringe, and in particular,
to a mechanism for locking a needle inside a hollow shield to prevent
repeated use.
Contaminated needles have become increasingly dangerous to people
in the medical profession due to the increase in people infected
with the AIDS virus and other infectious diseases. Therefore, various
syringes have been developed to cover the needles after use. Often,
the needle retracts to reduce the risk of pricks by an exposed contaminated
needle.
In addition, the re-use of a syringe by people addicted to injectable
drugs contributes to the spread of disease. Therefore, it is also
desirable to have a needle that can only be used once to prevent
drug users from sharing contaminated needles. Many improved syringes
have been developed that provide for the covering of a needle after
use. However, existing designs often have relatively complicated
constructions. In addition, some of these so called "single-use"
syringes can be returned to working order with minimal effort.
U.S. Pat. No. 4973316 shows a one-handed retractable safety syringe
where the needle retracts into the medicine barrel by further depressing
a plunger after the medicine has been injected. This overtravel
disengages two triggers, thereby releasing a spring that pushes
the needle holder and needle back into the barrel. U.S. Pat. No.
4978343 shows a similar structure but including a pimple on the
needle holder that rocks the needle after retraction into the housing
to prevent re-extension. In both patents the release mechanism is
located inside the medicine barrel near the needle end. Such a configuration
is relatively frail since it must be small enough to fit inside
the medicine barrel. Moreover clearing a jam in the inaccessible
trigger mechanism is difficult with an internal mechanism. In addition,
having moving parts inside the barrel where the medicament is held
could cause contamination if chips or fragments break off.
U.S. Pat. No. 5049133 shows a single-use safety syringe with
a needle mounted in a head that is held by teeth-like triggers.
When a plunger reaches an extreme position the triggers release
the needle and head which then retract into the hollow cavity in
the plunger under the urging of a compression spring. Again, the
trigger mechanism is internally located inside the medicine barrel
at the needle end. Accordingly, the mechanism would be prone to
jamming and fragment contamination.
In international patent PCT/EP89/01408 the needle of a single-use
syringe is held in a working position by a retaining member. After
use, the retaining member is released by further pressing the plunger
which allows a spring to retract the needle into the body. This
rather complicated device requires the cooperation of a large number
of internally located moving parts having the disadvantages noted
above.
Other patents, not analyzed in detail herein, have a releasable
needle shield, and may require two hands to lock the needle in the
working position before use and to release the needle after use.
The needle may be locked into place either by rotating the shield
or operating a button or clip. See U.S. Pat. Nos.: 4900311 5013301
4850977 4927416 4929237 4955868 and 5049136.
Accordingly there is a need for an effective safety syringe employing
a retractable needle that is reliable, simple to clear if jammed,
and unlikely to suffer from fragment contamination.
SUMMARY OF THE INVENTION
The present invention relates to a safety syringe, and in particular
to a mechanism for automatically retracting the needle after use
into a safety shield so the needle is no longer exposed.
It is an object of this invention to decrease the risk of harm
to the user from a hypodermic syringe by providing a syringe whose
needle is automatically retracted into a housing after a dose has
been injected, thereby preventing the user from being pricked by
the needle.
It is a further object of this invention to retract the needle
back into a shield in such a way that re-use is made difficult.
It is yet a further object of this invention to provide a safety
syringe that is reliable, efficient, and easy to manufacture.
An additional object of the invention is to have a syringe with
a catch mechanism allowing for easy clearing of a jam.
In accordance with the illustrated embodiments demonstrating features
and advantages of the present invention, there is provided a syringe
having an outer hollow shield. The shield has a plunger opening
and a needle opening. At least one locking lug is mounted at the
plunger opening. A lumen telescopically mounted at least partially
within the shield, has a catch for engaging the locking lug. A needle
is attached to the lumen and is aligned with the needle opening
in the shield. In addition, a plunger has an inner end slidably
mounted into the lumen and an outer end mounted through the plunger
opening. Mounted in the shield is an urging means mounted for urging
the lumen and retracting the needle into the shield. The outer end
of said plunger has an extension for engaging and deflecting the
locking lug to release the catch. Thus the urging means can retract
the needle into the shield.
By employing a device of the foregoing type, an improved safety
syringe is achieved. In a preferred embodiment, a shield is released
from a lumen by over-depressing a plunger into the lumen. The aforementioned
extension on the plunger, preferably a disc-shaped tab with beveled
ends, deflects a locking lug and releases the shield. The aforementioned
urging means can include a compression spring mounted between the
shield and the lock. Thus, the extension on the plunger can deflect
the locking lug, so the spring will retract the lumen and its lock
into the shield, sending the lock through the plunger opening. The
lock can then engage the locking lugs thereby securing the needle
in the shield.
BRIEF DESCRIPTION OF THE DRAWINGS
The above description, as well as other objects, features and advantages
of the present invention will be more fully appreciated reference
to the following detailed description of the presently preferred
but nonetheless illustrative embodiments in accordance with the
present invention when taken in conjunction with the accompanying
drawings, wherein:
FIG. 1 is a side view, partially in section, of a syringe according
to the principles of the present invention;
FIG. 2 is a side view of the syringe of FIG. 1 after the needle
retracts into the shield;
FIG. 3 is an end view of the shield of FIG. 1;
FIG. 4 is a cross-sectional view taken along line 4--4 of FIG.
3;
FIG. 5 is a detailed, cross-sectional view of the locking lug of
FIG. 1 holding a catch; and
FIG. 6 is a detailed view of the beveled extension releasing the
locking lug of FIG. 5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIGS. 1-4 a single-use safety syringe has an elongated
hollow shield 10. Shield 10 has a tube-like configuration with a
plunger opening 12 on one end and a needle opening 14 on the opposite
end. Shield 10 is shaped as a hollow cylinder but may be a hollow
prism or other shape in different embodiments. Shield 10 can be
transparent plastic, glass and the like. Finger supports 32 extend
transversely from shield 10 near plunger opening 12. Finger supports
32 are preferably rounded (see FIG. 3) with beveled edges, although
rectangular and other shapes are possible.
Shield 10 has six locking lugs 16 located at the plunger opening.
Lugs 16 are grouped into two trios. Each trio is equiangularly spaced
by 45 degrees. The trios are positioned on opposite sides of the
plunger opening 12. This arrangement allows for easy deflection,
although the number, shape and pattern of the locking lugs can be
varied.
Locking lugs 16 are preferably rectangular solids with a concave,
cylindrically shaped inside end. As shown in FIG. 5 the inside face
of lug 16 is slanted. The lugs, however, can have various other
solid shapes including cylindrical, spherical, prismatic, etc. Lugs
16 are mounted atop relatively flexible slender supports 17.
Lumen 18 is shown as a hollow cylinder telescopically mounted at
least partially within shield 10. Lumen 18 has a catch 19 for engaging
locking lugs 16 in the shape of a cylindrical, annular flange. Lumen
18 is preferably made of plastic, but can be made out of other materials
such as glass. Lumen 18 preferably has gradations marked on its
outside to facilitate determining the volume of medicine being dispensed.
Alternatively, gradations can be marked on shield 10.
Needle 20 is secured to holder 21. Needle 20 is attached to lumen
18 through holder 21 and is aligned with the needle opening 14 in
shield 10. Needle opening 14 is sized to encircle holder 21 when
the syringe is in the working condition.
Lock 28 (also referred to as a locking means) is a frustro-conical
skirt encircling lumen 18. Stop 30 is a frustro-conical flange encircling
lumen 18. Stop 30 is located between and spaced from needle 20 and
lock 28. The base 29 of lock 28 faces the base 31 of stop 30. A
compression spring 24 (referred to as an urging means) is mounted
in shield 10 between stop 30 and the needle end of the shield. Stop
30 is preferably frustro-conical and has a base diameter slightly
smaller than the diameter of the shield. Stop 30 can have a variety
of different shapes such as tetrahedral or cylindrical. Lock 28
is also frustro-conical, is smaller than stop 30 and can also have
a variety of shapes.
Plunger 22 has an inner end 23 slidably mounted in lumen 18. Plunger
22 is also mounted within plunger opening 12. The inner end 23 of
plunger 22 has a cruciform midsection and a gasket to pressurize
and dispense medicine in lumen 18. The outer end of the plunger
22 has a thumb flat 34 and an extension 26. Extension 26 is sized
to engage and deflect locking lugs 16 when thumb flat 34 is over-depressed.
To facilitate an understanding of the principles associated with
the foregoing apparatus, its operation will now be briefly described.
The syringe is delivered in the condition shown in FIG. 1 with
needle 20 exposed. As shown in FIG. 5 catch 19 is held by lug 16
at this time.
First the syringe is loaded from an ampoule (not shown) in the
usual fashion. Essentially, needle 20 is inserted into an ampoule
with the ampoule and syringe inverted. The medicament is withdrawn
by pulling plunger 22 partially out of lumen 18 until the appropriate
amount of medicine has been obtained. The needle is then pulled
from the ampoule. Next, the user slightly depresses thumb flat 34
to remove any excess air. The syringe is now filled and ready for
use.
In the preferred embodiment, when injecting, the user's fingers
go around each of the finger supports 32 while the thumb is positioned
on thumb flat 34. The needle 20 is then inserted into a patient
and plunger end 23 is driven toward needle 20 thereby injecting
the medicament. The needle can then be removed from the patient.
Next, plunger 22 is depressed further to force beveled extension
26 against locking lugs 16. Further pressure causes extension 26
to spread apart locking lugs 16 of the shield 10 as shown in FIG.
6. From the detailed view of FIG. 6 beveled extension 26 deflects
locking lug 16 releasing catch 19. Since the catch is located near
plunger opening 12 and jamming can easily be rectified. The release
of catch 19 permits the entire body of the syringe to retract into
the shield by the urging of spring 24 until stop 30 engages the
underside of locking lugs 16 as shown in FIG. 2. This secures needle
20 inside the shield so that the syringe can no longer be used.
As the safety syringe retracts, lock 28 enters plunger opening
12. The slanted sides of lock 28 act as a camming surface to spread
lugs 16 apart. As lock 28 travels, its trailing edge eventually
passes lugs 16 which then snap closed behind lock 28. This snapping
looks the syringe in the safe position and makes re-use difficult.
When in the safe condition of FIG. 2 the base 31 of stop 30 rests
against the underside of locking lugs 16. Top lock 28 and stop 30
are separated a distance approximately equal to the thickness of
the locking lugs to prevent movement. In the position shown in FIG.
2 the needle segment is locked into the shield in such a way that
it can no longer be readily reactivated.
Obviously, many modifications and variations of the present invention
are possible in light of the above teachings. It is therefore to
be understood that within the scope of the appended claims, the
invention may be practiced otherwise than as specifically described.
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