Safety syringe abstract
A needle holder positioning structure for a safety syringe includes
a syringe with a neck portion having a top end forming a positioning
projecting ring, an inner edge of a lower end of the neck portion
upwardly and integrally formed with a forked elastic sleeve, with
a terminus inwardly forming hook members, a bottom end of a needle
holder for receiving a needle being inwardly provided with a flared
hole having a distal end forming an enlarged opening, the bottom
end of the needle holder being outwardly provided with a guide face,
and an outer side formed with depressions corresponding to the hook
members.
Safety syringe claims
What is claimed is:
1. A needle holder positioning structure for a safety syringe,
comprising a syringe with a neck portion having a top end forming
a positioning projecting ring, an inner edge of a lower end of said
neck portion upwardly and integrally formed with a forked elastic
needle sleeve, with a terminus inwardly forming hook members, a
bottom end of a needle holder for receiving a needle being inwardly
provided with a flared hole having a distal end forming an enlarged
opening, the bottom end of said needle holder being outwardly provided
with a guide face, and an outer side formed with depressions corresponding
to said hook members.
2. The needle holder positioning structure for a safety syringe
of claim 1 wherein said needle sleeve fitted on said positioning
projecting ring has an outer edge provided with recesses corresponding
to said hook members.
Safety syringe description
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The invention relates to a needle holder positioning structure
for a safety syringe, more particularly to a low-cost structure
that allows precise positioning.
(b) Description of the Prior Art
R.O.C. Patent Publication No. 332433 discloses an improved safety
syringe structure having a needle holder positioning structure as
shown in FIGS. 6 to 10. A rear end of a needle holder 5 is provided
with a flared hole 51 which is enlarged to form an arrow-shaped
cavity 52 for receiving an arrow-shaped coupling member 62 provided
at the front end of a piston head 61 of a piston 6. After injection,
the coupling member 62 and the cavity 52 are coupled integrally.
Therefore, when the piston 6 is pulled back, the needle holder 5
together with the needle 53 is disengaged from the neck portion
71 of the syringe 7 to pull the needle 63 into the interior of the
syringe body 72 of the syringe 7 so as not to expose on the outside
to ensure safety.
Further, since in that patent the needle holder 5 is disposed in
the neck portion 71 of the syringe 7 in order that the needle holder
5 can be smoothly pulled back, the needle holder 5 must be formed
from elastic rubber material instead of the conventionally used
plastic material. However, as rubber is much more expensive than
plastic, and the elastic characteristic of rubber may affect the
positioning of the needle 53 that patent has the disadvantages
of high costs and improper positioning.
There are other related prior art patents, which include U.S. Pat.
Nos. 4932939 5163907 5910130 5879339 5902277 5902271
5902270 5902269 5395346 4737144 5344403 and 5569203.
SUMMARY OF THE INVENTION
The primary object of the present invention is to provide a needle
holder positioning structure for a safety syringe, which is inexpensive
to manufacture.
Another object of the present invention is to provide a needle
holder positioning structure for a safety syringe, which permits
precise positioning of the needle.
In order to achieve the above objects, the present invention is
characterized in that the inner edge of a lower end of a neck portion
of a syringe is upwardly and integrally formed with a forked elastic
sleeve and hook members, and a needle holder is corresponding provided
with depressions so as to couple the needle holder to the neck portion
of the syringe by means of hooking and elastic retention, and the
needle holder together with the needle can be pulled back into the
interior of the syringe. Furthermore, the needle holder can be made
of plastic material. Plastic needle holders are low-cost and permit
precise positioning as compared with rubber needle holders.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other features and advantages of the present
invention will be more clearly understood from the following detailed
description and the accompanying drawings, in which,
FIG. 1 is a sectional view of the structure of the embodiment of
this invention prior to coupling;
FIG. 2 is a sectional view of the structure of the embodiment of
this invention after coupling;
FIG. 3 is a schematic view showing the embodiment of this invention
assembled to a safety injection syringe;
FIG. 4 is a schematic view illustrating pulling back of the embodiment
of this invention;
FIG. 5 is a schematic view illustrating reverse fitting of a needle
sleeve of the embodiment of this invention;
FIG. 6 is a schematic view showing a needle holder positioning
structure of Publication No. 332433;
FIG. 7 is a schematic view showing the process of reverse pulling
of the needle holder of Publication No. 332433;
FIG. 8 is another schematic view showing the process of reverse
pulling of the needle holder of Publication No. 332433;
FIG. 9 is a further schematic view showing the process of reverse
pulling of the needle holder of Publication No. 332433; and
FIG. 10 is still another schematic view showing the process of
needle entrapment in syringe casing of the holder of Publication
No. 332433.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference to FIGS. 1 and 2 the invention includes a syringe
1 having a neck portion 11 that forms a positioning projecting ring
12 at a top end. The inner edge of the lower end of the neck portion
11 upwardly and integrally forms a forked elastic sleeve 13 and
hook members 14 are formed inwardly at the terminus. The rear end
of a needle holder 2 for receiving a needle 21 is inwardly provided
with a flared hole 22 with a distal end forming an enlarged opening
23. The bottom end of the needle holder 2 is outwardly formed with
a guide face 24 with depressions 25 formed in the outer side to
correspond to the hook members 14.
With reference to FIG. 3 the positioning projecting ring 12 serves
to position a needle sleeve 3. The front end of a piston head 41
of a piston 4 is provided with a coupling member 42 corresponding
to the flared hole 22 and the enlarged opening 23 of the needle
holder 2 so as to permit retraction of the needle holder 2 with
the needle 21. However, as such a structure is not the subject matter
of this invention, it will not be described in detail herein. Referring
to FIGS. 3 and 5 the outer edge of the needle sleeve 3 is provided
with recesses 31 corresponding to the hook members 14. When the
needle 21 is pulled back to the interior of a syringe body 15 the
needle sleeve 3 is fitted in a reverse direction to cause the recesses
31 and the hook members 14 to come to a retained state, thereby
preventing extension of the needle and leakage of possible residual
blood in the syringe 1 to ensure safety.
Based on the above construction, the flared hole 22 of the needle
holder 2 is configured to be able to retract inwardly and elastically,
the guide face 24 guides into the neck portion 11 of the syringe
1 the depressions 25 retain the hook members 14 of the syringe
1 and the elastic sleeve 13 positions the needle holder 2 firmly
with its inward retaining force (see FIG. 2). In addition, after
injection, when the piston 4 is pulled back (the relationship between
the piston 4 and the needle holder 2 being described hereinabove),
the back pulling force may offset the inward retaining force of
the elastic sleeve 13 to cause the needle 21 to be pulled back into
the interior of the syringe body 15. Therefore, this invention employs
hooking and elastic retaining force to couple the needle holder
2 to the neck portion 11 of the syringe 1 and is directly formed
by plastic injection molding, without the need to use rubber material
as in the prior art. This not only reduces costs, the plastic needle
holder allows more precise positioning of the needle 21.
Although the present invention has been illustrated and described
with reference to the preferred embodiment thereof, it should be
understood that it is in no way limited to the details of such embodiment
but is capable of numerous modifications within the scope of the
appended claims. |