Medical syringe abstract
There is disclosed a single use, destructible, medical syringe
in which the barrel and plunger are provided with structural elements
which break of a portion of the plunger or lock the plunger in place
in the barrel after an initial use. The syringe is simple in structure
and made of a plastic, such as polyethylene.
Medical syringe claims
What is claimed is:
1. A single use, destructible medical syringe comprising a barrel
provided with a needle or adapted for connection to a needle at
one end, an opposite open end, and a plunger disposed in said barrel,
said plunger provided with a cap at the end thereof nearest the
open end of said barrel and a frangible seal attached to the opposite
end, said barrel having a countersunk portion extending from the
vicinity of the open end towards the needle-bearing end thereof,
and means for preventing withdrawal of said plunger intact from
said barrel comprising a boss extending around the internal surface
of said barrel above said countersunk portion, bearing against said
seal to break the seal upon withdrawal of the plunger, whereby after
initial use further use of said syringe is prevented.
2. A single use, destructible medical syringe according to claim
1 including a clip comprising a base member having an open notch
therein, said notch disposed around the external surface of the
plunger between the lower surface of the cap thereof and the open
end of the barrel of said syringe.
3. A single use, destructible medical syringe according to claim
1 including a needle guard disposed on the barrel at the needle-bearing
end of said syringe.
4. A single use, destructible, medical syringe according to claim
1 including a cover disposed on the barrel at the open end thereof.
5. A single use, destructible, medical syringe according to claim
1 wherein the open end of the barrel is provided with an enlarged
cup-like portion having an internal groove therein, the internal
surface of said groove having an outwardly divided boss located
thereon, the cap of the plunger being provided with a depending
peripheral skirt provided with an inwardly directed edge which passes
over said boss when said plunger is moved into said barrel, whereby
after an initial use contact between said boss and the inwardly
directed skint locking said plunger into said barrel and preventing
further use of said syringe.
6. A single use, destructible, medical syringe according to claim
5 including a sleeve located in the barrel above the countersunk
portion of said barrel.
7. A single use, destructible, medical syringe according to claim
1 wherein the barrel and the plunger are made of plastic.
8. A single use, destructible, medical syringe according to claim
7 wherein the plastic is polyethylene.
9. A single use, destructible, medical syringe according to claim
1 wherein the seal is made of rubber.
10. A single use, destructible, medical syringe according to claim
6 wherein the sleeve is made of rubber.
Medical syringe description
This invention relates to syringes. More particularly, the invention
relates to medical syringes for intravenous and other injections
which self-destruct after an initial use and thus are used only
BACKGROUND OF THE INVENTION
As is well-known, the repetitious use of medical syringes without
proper sterilization is in a large part responsible for the tragic
spread of diseases, such as AIDS and Hepatitis B, among others.
This problem has resulted in the attempted development of disposable
syringes which are produced and made available to anyone requesting
them. Unfortunately, these so-called "disposable" syringes
are disposable in theory only and, in actual practice, are readily
capable of re-use, as are conventional syringes. Moreover, since
sterilization of reusable syringes requires special equipment and
is time consuming and expensive, the use of the cheaper and so-called
expendable disposable syringes has proliferated.
Syringes intended for a single use are also known. A wide variety
of such syringes have been developed. However, most of them are
complex in structure and thus, expensive to make. For example, one
such device comprises a combined ampoule and syringe in which the
piston or plunger is provided with a joint at the end placed inside
the cylinder of the syringe. The joint, which is separable from
the piston, is designed to remain in its final position at the bottom
of the cylinder when the injection is completed. Other such devices
of this sort have other drawbacks.
There exists, therefore, a need for a single use, destructible,
medical syringe which does not exhibit the disadvantages and drawbacks
of the known disposable syringes. The present invention fulfills
such a need.
BRIEF STATEMENT OF THE INVENTION
In accordance with the present invention there is provided a single
use, destructible, medical syringe comprising a barrel, to which
a needle is connectable at one end and a plunger is disposable through
the opposite end. Mounted at the inner end of the plunger is a seal
member. The barrel of the syringe is provided with a countersunk
portion between the open end and the needle-bearing end. Located
above the continuing portion is means for preventing withdrawal
of the plunger in an intact condition, so that after initial use
of the syringe any movement of the plunger to refill the syringe
In order to understand the invention more fully, reference is made
to the accompanying Drawings which are to be taken in conjunction
with the following detailed description of the preferred embodiments
of the invention and in which Drawings:
FIG. 1 is a front view in section of a medical syringe of one embodiment
according to the invention showing the construction of the barrel
and plunger disposed therein;
FIG. 1A is an enlarged view of the lower end of the syringe of
FIG. 1 showing frangible rubber seal disposed on the end of the
plunger in the vicinity of the needle bearing portion of the barrel;
FIG. 1B is an enlarged view of the upper end of the syringe showing
the means for separating the frangible seal from the plunger;
FIG. 2 is a modification of the syringe illustrated in FIG. 1 employing
a safety clip disposed between the lower surface of the cap of the
plunger and the open end of the barrel;
FIG. 3 is a frontal elevational view in section of a modification
of a syringe according to the invention;
FIG. 4 is a partial front view in section of an illustration of
another embodiment of the syringe of the invention showing a qualification
in which the barrel is provided with a modified open end and modified
cap on the plunger which locks the plunger in place after initial
use of the syringe;
FIG. 5 is a partial, exploded, sectional view of the syringe illustrated
in FIG. 3 showing the enlarged open end of the barrel in detail;
FIG. 6 is a plan view of the safety lock; and
FIGS. 7a and 7b are views of a modified plunger and sleeve.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to FIG. 1 syringe embodying the invention is generally
depicted by the numeral 10. The syringe is formed of a barrel 12
which may be of circular cross section and at least in its interior
of uniform diameter. At the far end of the barrel 12 there is provided
a fitting 14 to which a needle N is attached. The opposite or open
end of the barrel generally depicted by the numeral 16 is formed
within an enlarged portion 18 having an outwardly extending rim
20 for supporting the syringe between the fingers of the user. A
plunger 22 having a cap 24 extends through the opening into the
barrel 12. The interior of the opening is provided with a stepped
shoulder 26 against which the cap 24 may rest when the plunger is
fully inserted into the barrel.
As seen in FIGS. 1A and 1B the far end of the plunger 22 is provided
with an outwardly extending boss 28 which is weakened as shown by
broken lines 30 so that the boss 28 is frangible. Mounted on the
box 28 is a cap seal 32 forming a piston head slidable on the inner
surface of the barrel. Disposed on the internal surface of the barrel
just below the finger rim 20 is a countersunk portion thereof is
an inwardly directed circumferential lip 34 adapted to engage the
end of the cap seal 32 when the plunger is withdrawn (FIG. 1B) thereby
preventing withdrawal of the plunger from the barrel and destruction
of the frangible boss 28. Consequently, although the syringe is
manufactured and filled with medication or the like to be dispensed
therefrom, it cannot be re-used since when the user withdraws the
plunger for purposes of refilling the syringe the lip 34 will cause
the boss 28 carrying the seal to be broken away, thus preventing
further use of the syringe.
The syringe is provided with a U-shaped safety clip 36 FIG. 6
having a slot 38 provided and an upwardly extending gripping member
40. The safety clip 36 is adapted to be disposed between the lower
surface of the plunger cap 24 and the upper surface of the enlarged
portion 18 of the barrel end (as in FIG. 2) to hold the plunger
in a deactivated position and prevent the plunger from being prematurely
depressed until the clip is removed from position.
All of the described elements except for the rubber seal may be
made of rigid plastic, such as nylon, polyurethane and polyethylene
or the like. Of the materials, polyethylene is preferred. While
the seal is preferably made of rubber, it is within the purview
of this invention to make it of any similar material such as silicone
rubber, for example. If desirable, the syringe shown in FIG. 2 may
also be provided with a cover 44 which fits over the open end 16
of the barrel and rests on finger rim 20 of the barrel.
The embodiment illustrated in FIGS. 3 through 6 provides additional
features which prevent re-use by locking the plunger in place once
it has been pushed into the barrel in addition to the breaking of
the frangible seal.
Referring next to FIGS. 3 through 6 it is seen that the enlarged
open end cup-like portion of the barrel is provided with an internal
recess 46. The internal surface of the recess has an outwardly directed
flange 48 located thereon while the cap 21 of is provided with a
depending peripheral skirt 50 having an inwardly directed flange
52 which passes over the boss 48 when the plunger is moved into
the barrel into locking engagement with the flange 48 of the recess.
This locks the plunger into the barrel and prevents further use
of the syringe.
In addition a sleeve 54 preferably of rubber, is located within
the barrel above the countersunk portions. Sleeve 54 is bonded to
the internal surface by sonic welding. Thus, should the locking
features of the cap and cup like portion fail, the sleeve 54 will
prevent withdrawal of the plunger and break the frangible end of
the plunger with the rubber seal and thus prevent reuse of the syringe.
A needle guard (not shown) may also be employed.
In FIGS. 7a and 7b, a modified plunger is shown to have an upper
section 60 of a larger outer diameter than the lower section 62.
As a result, a shoulder 64 is formed between the sections. Slidably
disposed over the interfacing shoulder 64 is a sleeve having self
conforming diameter sections 66 and 68 with an inward shoulder 70.
An elastic seal piston head 72 is attached at the end of the lower
piston rod. Otherwise, the structure is the same and functions in
the same manner as previously described.
It will be apparent that with very little additional structure,
a truly single use syringe is formed. The internal plunger and plunger
head will be automatically broken upon any attempt to withdraw the
plunger, preparatory to refilling the barrel. Ancillary features
reside in providing for a safety lock preventing premature ejection
of the contents of the barrel (FIG. 2) and/or freedom of movement
of the plunger once the syringe has been emptied (FIGS. 5 and 6).
While various modifications and changes have been disclosed, others
will be obvious to the reader. Accordingly, the present disclosure
should be taken as illustrative only and not limiting of the scope
of the invention.