Note: Descriptions are shown in the official language in which they were submitted.
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DISPOSABLE SYRINGE WITH BUILT-IN CARPULE
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a disposable syringe, more
particularly to a disposable syringe with a carpule.
2. Description of the Related Art
In U.S. Patent No. 6,221, 055 B1 for a retractable dental
syringe as shown in Figs. 1 and 2, there is disclosed a
pre-filled syringe 9, which includes a barrel 91 having an
open widened rear end 911 to receive an operating end 973
of a plunger 97, a needle holder 93 for holding a double-ended
needle 94, a push ring 92 for holding the needle holder 93
in the barrel 91, a biasing member 95 disposed between a
front end 912 of the barrel 91 and the needle holder 93,
and a carpule 96 positioned in the barrel 91 from the rear
end 911. The carpule 96 has a front seal 963 disposed to
seal a front end 962 thereof, and a slidable piston seal
including an outer rim member 99 and a releasable core member
98 to seal a rear end 961 of the carpule 96 so as to define
a sealed medicament chamber 964. The plunger 97 has inner
and outer walls 971,972 parallel to and spaced apart from
each other and connected at the operating end 973.
In operation, the rear end 961 of the carpule 96 is
associated with the front of the plunger 97. Then the plunger
and carpule assembly is introduced into the barrel 91 from
the rear end 911, and the carpule 96 is moved forwardly until
the front seal 963 is punctured by a communicating end 941
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of the needle 94, as shown in Fig. 1. As a tip end 942 of
the needle 94 is inserted into a patient, the plunger 97
is pressed forwardly to inject the contents of the chamber
964 through the needle 94, as shown in Fig. 2. At the end
of an injection, the plunger 97 is further pressed to move
the carpule 96 forwardly to remove the push ring 92, thereby
freeing the needle holder 93 for retraction of the needle
holder 93, the needle 94, the front seal 963 and the core
member 98 into the carpule 96 by virtue of a biasing action
of the biasing member 95, as shown in Fig. 3.
Although the syringe 9 can be operated to retract the
needle 94 for safe disposal, the following drawbacks arise:
1. The assembly of the carpule 96 and the plunger 97
to the barrel 91 before the injection operation is
complicated and inconvenient to conduct. In addition, with
such construction, the carpule 96 cannot be accommodated
in the barrel 91 in advance, and the carpule 96 and the barrel
91 have to be packed separately for subsequent assembly in
use, thereby resulting in increased operation time.
2. Since the used needle 94 and the needle holder 93
are retracted within the inner wall 971 of the plunger 97,
before triggering the biasing action of the biasing member
95, the respective retaining engagements between the push
ring 92 and the needle holder 93, between the front seal
963 and the carpule 96, and between the core member 98 and
the outer rim member 99 have to be released at the same time.
Thus, the retraction of the used needle 94 may fail. Such
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complicated structural relationship makes the manufacture
of the syringe 9 troublesome.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a
disposable syringe with a built-in carpule which ensures
retraction of a used needle into a syringe barrel for safe
disposal, which has a carpule that can be pre-assembled in
the barrel before injection so that the injection operation
is simplified and convenient to conduct, and which can be
conveniently rendered unreusable after injectionina single
operation.
According to this invention, the disposable syringe with
a built-in carpule includes a barrel including front and
rear barrel ends opposite to each other along an axis in
an axial direction, a surrounding barrel wall which
interconnects the front and rear barrel ends, and which
includes front and rear wall portions that are disposed
proximate to the front and rear barrel ends, respectively,
and that define front and rear compartments, respectively.
A needle cannula has a tip end which is disposed forwardly
of the front barrel end in a position of use, and a
communicating end which is opposite to the tip end along
the axis. A seat member has a surrounding gripped portion
surrounding the axis. A grip member is detachably retained
on the rear wall portion, and is configured to be frictionally
engaged with the gripped portion to provide a resisting force
that guards the gripped portion against movement relative
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to the rear wall portion in the axial direction during a
piercing action of the needle cannula for injection, and
that permits disengagement of the grip member from the
gripped portion so as to enable a subsequent movement of
the seat member when the gripmember is subj ected to a pressing
force. A carpule has a tubular wall which is configured to
be fit in the rear compartment, and which extends towards
the grip member to terminate at a tubular edge surface, and
front and rear seal members which are spaced apart from each
other in the axial direction, andwhich, in cooperation with
the tubular wall, form a sealed chamber for holding liquid
medicament. The rear seal member is disposed to be movable
to abut against the front seal member in an initial course
so as to expel the liquidmedicament out of the sealed chamber,
thereby placing the carpule in a used-up position. The front
seal member has a mating surface which is configured to permit
the communicating end to be retained with and to pass through
the mating surface such that the needle cannula is in fluid
communication with the sealed chamber, and such that once
the rear seal member abuts against the front seal member
in the used-up position, the pressing force is transmitted
through the tubular wall to force the tubular edge surface
against the grip member in a subsequent course so as to effect
disengagement of the grip member from the gripped portion,
thereby placing the seat member in a disengaging position,
where the mating surface is closer to the front barrel end
than when the carpule is in the used-up position. A plunger
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has a push end which is disposed to move the rear seal member
forwardly along the tubular wall to bring the carpule to
the used-up position, and to move the mating surface
forwardly from the used-up position so as to permit the seat
5 member to be placed in the disengaging position, and an
operating end which is opposite to the push end in the axial
direction, and which is disposed to extend outwardly of the
rear barrel end to be subjected to an external force which
is greater in the subsequent course than in the initial course.
A biasing member is disposed in the front compartment such
that, once the seat member is in the disengaging position,
the biasing member biases the seat member together with the
carpule towards the rear barrel end to retract the tip end
of the needle cannula into the barrel, thereby placing the
needle cannula in a disposal position.
BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages of the present invention
will become apparent in the following detailed description
ofthe preferred embodiments of the invention, with reference
to the accompanying drawings, in which:
Fig. 1 is a sectional view of a conventional retractable
syringe in a ready-to-use position;
Fig. 2 is a sectional view of the conventional retractable
syringe in a state after completion of an injection stroke;
Fig. 3 is a sectional view of the conventional retractable
syringe, showing that a needle-holding structure is fully
retracted into a carpule;
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Fig. 4 is an exploded sectional view of the first preferred
embodiment of a disposable syringe according to this
invention;
Fig. 5 is a sectional view of the first preferred
embodiment in an initial assembled position;
Fig. 6 is a fragmentary sectional view of the first
preferred embodiment;
Fig. 7 is a sectional view of the first preferred
embodiment during an injection stroke;
Fig. 8 is a sectional view of the first preferred
embodiment after completion of the injection stroke;
Fig. 9 is a sectional view of the first preferred
embodiment, showing the state of disengagement of a seat
member from a grip member;
Fig. 10 is a sectional view of the first preferred
embodiment, showing that a needle cannula is fully retracted
into a barrel;
Fig. 11 is a sectional view of the second preferred
embodiment of a disposable syringe according to this
invention;
Fig. 12 is a sectional view of the third preferred
embodiment of a disposable syringe according to this
invention in the initial assembled position;
Fig. 13 is a sectional view of the third preferred
embodiment during an injection stroke;
Fig. 14 is a sectional view of the third preferred
embodiment, showing that a needle cannula is fully retracted
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into a barrel;
Figs. 15 to 18 respectively are sectional views of the
fourth, fifth, sixth, and seventh preferred embodiments of
a disposable syringe according to this invention;
Fig. 19 is a sectional view of the eighth preferred
embodiment of a disposable syringe according to this
invention in the initial assembled position;
Fig. 20 is a sectional view of the eighth preferred
embodiment, showing that a needle cannula is fully retracted
into a barrel;
Fig. 21 is a sectional view of the ninth preferred
embodiment of a disposable syringe according to this
invention;
Fig. 22 is an exploded sectional view of the tenth
preferred embodiment of a disposable syringe according to
this invention;
Fig. 23 is a sectional view of the tenth preferred
embodiment in the initial assembled position;
Figs. 24 and 25 respectively are sectional views of the
eleventh and twelfth preferred embodiments of a disposable
syringe according to this invention;
Fig. 26 is a sectional view of the thirteenth preferred
embodiment of a disposable syringe according to this
invention in the initial assembled position;
Fig. 27 is a sectional view of the thirteenth preferred
embodiment, showing that a needle cannula is fully retracted
into a barrel; and
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Fig. 28 is a sectional view of the fourteenth preferred
embodiment of a disposable syringe according to this
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Before the present invention is described in greater
detail, it should be noted that same reference numerals have
been used to denote like elements throughout the
specification.
Referring to Figs. 4 to 6, the first preferred embodiment
of a disposable syringe according to the present invention
is shown to comprise a barrel 1, a needle cannula 23, a seat
member 22, a grip member 21, a biasing member 24, a tip
protector 25, a carpule 3, a plunger 4, and a plunger protector
5.
The barrel 1 includes front and rear barrel ends 122, 121
opposite to each other along an axis in an axial direction,
a surrounding barrel wall 12 which interconnects the front
and rear barrel ends 122, 121, and which includes front and
rear wall portions 124,123 that are disposed proximate to
the front and rear barrel ends 122,121 respectively, and
that define front and rear compartments (lla,llb),
respectively, and a finger flange 15 which is disposed
proximate to the rear barrel end 121. In this embodiment,
the rear compartment (llb) is larger than the front
compartment (lla) in diameter so as to form a front annular
shoulder 125 therebetween. The shoulder 125 has a plurality
of fins 14 which extend towards the axis to terminate at
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an inner peripheral edge 141 that surrounds the axis.
Moreover, a recess-like retaining portion 126 is disposed
in the rear compartment (llb) adjacent to the rear barrel
end 121. An annular stopper 127 is disposed forwardly of
the retaining portion 126. A retaining ring 128 is disposed
on the rear wall portion 123 adj acent to the front wall portion
124.
The needle cannula 23 has a tip end 232 which is disposed
forwardly of the front barrel end 122 in a position of use
(as shown in Fig. 5), and a communicating end 231 which is
opposite to the tip end 232 along the axis andwhich is pointed.
The seat member 22 has a rear seat end surface 225 which
holds the needle cannula 23, which permitsrearward extension
of the communicating end 231 of the needle cannula 23
therethrough, and which confronts rearwardly, a surrounding
gripped portion 222 which surrounds the axis, and a
surrounding front abutment surface 223 which is opposite
to the rear seat end surface 225 andwhich confronts forwardly.
The seat member 22 further has a tubular mount 226 which
extends from the surrounding front abutment surface 223 into
the front compartment (lla) , and which is spaced apart from
the inner peripheral edge 141 in radial directions by an
inserted clearance that receives a lower end 242 of the
biasing member 24 so as to permit the biasing member 24 to
abut against the surrounding front abutment surface 223.
The biasing member 24 is disposed in the front compartment
(11a) , and has an upper end 241 abutting against the front
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barrel end 122. The seat member 22 further has an annular
stepped surface 227 which is spaced apart from the fins 14
of the shoulder 125 in the axial direction, and which extends
radially and outwardly to join the gripped portion 222, and
5 a plurality of fin spacers 221 which are angularly displaced
from one another about the axis, and each of which is
interposed between the annular stepped surface 227 and the
fins 14 so as to brace the annular stepped surface 227 against
the shoulder 125.
10 The grip member 21 is detachably retained on the rear
wall portion 123 by a retaining ring 128, and is configured
to be frictionally engaged with the gripped portion 222 so
as to provide a resisting force that guards the gripped
portion 222 against movement relative to the rear wall
portion 123 in the axial direction during a piercing action
of the needle cannula 23 for injection, and that permits
disengagement of the grip member 21 from the gripped portion
222 so as to enable a subsequent movement of the seat member
22 when the grip member 21 is subjected to a pressing force.
The tip protector 25 is removably sleeved on the barrel
wall 12 for shielding the needle cannula 23 in the position
of use.
The carpule 3 has a tubular wall 32 which is configured
to be fitted in the rear compartment ( llb) , and which extends
in the axial direction to terminate at a tubular edge surface
322 and a rear wall end 321. The carpule 3 further has front
and rear seal members 35, 34 which are spaced apart from each
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other in the axial direction, and which, in cooperation with
the tubular wall 32, form a sealed chamber 31 for holding
liquid medicament. The front seal member 35 is secured to
the tubular wall 32 by means of inter-engagement of female
and male engaging portions 352,324. The rear seal member
34 is limited to the tubular wall 32 by means of
inter-engagement of female and male engaging portions
341,323 so as to guard against undesired movement of the
rear seal member 34 before inj ection, and is forced forwardly
to permit disengagement of the female engaging portion 341
from the male engaging portion 323 to be moved to abut against
the front seal member 35 in an initial course so as to expel
the liquid medicament out of the sealed chamber 31, thereby
placing the carpule 3 in a used-up position, as shown in
Fig. 8. The front seal member 35 has a mating surface 354
which is configured to have a cavity 351 that extends inwardly
and towards the sealed chamber 31. Thus, when the carpule
3 is assembled in the rear compartment (llb), the pointed
communicating end 231 of the needle cannula 23 can pierce
the mating surface 354 of the front seal member 35 to be
retained in and to pass through the mating surface 354 such
that the needle cannula 23 is in fluid communication with
the sealed chamber 31, as shown in Fig. 7. Moreover, the
tubular wall 32 of the carpule 3 has a rear annular shoulder
33 which extends radially and inwardly from the rear wall
end 321 to guard against a rearward movement of the rear
seal member 34 relative to the tubular wall 32. Thus, once
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the rear seal member 34 abuts against the front seal member
35 in the used-up position, thepressing force is transmitted
through the tubular wall 32 to force the tubular edge surface
322 against the grip member 21 in a subsequent course so
as to effect disengagement of the grip member 21 from the
gripped portion 222, thereby placing the seat member 22 in
a disengaging position, as shown in Fig. 9, where the mating
surface 354 is closer to the front barrel end 122 than when
the carpule 3 is in the used-up position. At this time, the
gripped portion 222 is received in the cavity 351 to ensure
that the carpule 3 is kept together with the seat member
22.
The plunger 4 includes first and second plunger bodies
43,41. The first plunger body 43 has a push end 432 which
is connected to the rear seal member 34 by virtue of a
frictional force, and a first rear end portion 433 opposite
to the push end 432 in the axial direction. The second plunger
body 41 includes an operating end 42 which is disposed to
extend outwardly of the rear barrel end 121 to be subjected
to an external force (i.e., a pressing force applied by a
user) that is greater in a subsequent course ( i. e. , a needle
retraction stroke) than in an initial course (i.e., an
injection stroke) , and a second front end portion 413 which
is opposite to the operating end 42, and which is releasably
retained with the first rear end portion 433 by means of
a mating engagement between an annular retaining protrusion
411 and an annular retaining groove 431 so as to generate
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a frictional force that is greater than the external force
in the initial course and is smaller than the external force
in the subsequent course. Moreover, the second plunger body
41 has an abutment 412 which is disposed on the second front
end portion 413.
The plunger protector 5 is detachably sleeved on the
rear wall portion 123 for shielding the plunger 4, and has
a releasably engaging region 53 which is disposed on a
peripheral wall 51 thereof and which is brought into
frictional engagement with a periphery 421 of the operating
end 42 of the plunger 4 when the plunger protector 5 is sleeved
on the rear wall portion 123. The plunger protector 5 further
has a step edge 52 which is disposed to abut against the
rear barrel end 121 for positioning the plunger protector
5 in place.
Referring to Figs. 5 and 7, in the injection stroke,
the tip and plunger protectors 25,5 are removed first to
expose the needle cannula 23 and the plunger 4. The operator
holds the finger flange 15 with his/her index and middle
fingers and presses the operating end 42 of the plunger 4
forwardly with his/her thumb such that the carpule 3 is moved
forwardly in the rear compartment (llb) to cause the
communicating end 231 of the needle cannula 23 to pierce
the mating surface 354 of the front seal member 35 so as
to communicate the needle cannula 23 with the sealed chamber
31. The external pressing force is subsequently applied to
the operating end 42 to cause the rear seal member 34 to
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be moved forwardly along the tubular wall 32 of the carpule
3 so as to place the carpule 3 in the used-up position, thereby
completing the injection stroke, as shown in Fig. 8. When
the carpule 3 is in the used-up position, the abutment 412
of the plunger 4 abuts against the rear annular shoulder
33 so as to impart the external force to the tubular wall
32 of the carpule 3.
As shown in Figs. 8 and 9, the external pressing force
is subsequently applied to the operating end 42 to force
the tubular edge surface 322 against the grip member 21 so
as to effect disengagement of the grip member 21 from the
gripped portion 222 resulting from blocking of the seat
member 22 by the fins 14, thereby placing the seat member
22inthe disengaging position.In this embodiment, referring
once again to Fig. 6, the front abutment surface 223 of the
seat member 22 is spaced apart from the fins 14 by a small
clearance in the position of use. The clearance can serve
as a triggering space for facilitating a rearward movement
of the seat member 22 after the seat member 22 is moved
forwardly with the front seal member 35 to bring the front
abutment surface 223 into abutment against the fins 14.
Once the grip member 21 is blocked by the fins 14, the
external pressing force causes the gripped portion 222 of
the seat member 22 to be received in the cavity 351 in the
front seal member 35, further causes the disengagement of
the retaining protrusion 411 of the second plunger body 41
from the retaining groove 431 in the first plunger body 43
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to permit a forward movement of the second plunger body 41
relative to the first plunger body 43 until the periphery
421 of the operating end 42 is retained with the retaining
portion 126 of the barrel 1 so as to guard against a rearward
5 movement of the second plunger body 41 for preventing reuse
of the syringe.
As shown in Fig. 10, when the seat member 22 is in the
disengaging position, thebiasingforce ofthe biasing member
24 is released to bias the seat member 22 together with the
10 carpule 3 towards the rear barrel end 121 so as to retract
the tip end 232 of the needle cannula 23 into the front
compartment (lla), thereby placing the needle cannula 23
in a disposal position. The carpule 3 is stoppedby the annular
stopper 127. At the same time, a large part of the first
15 plunger body 43 is retracted into the second plunger body
41.
Referring to Fig. 11, the second preferred embodiment
of a disposable syringe according to this invention is shown
to be similar to the previous embodiment in construction.
In the second embodiment, the front seal member 35 has an
annular flange 353 which is disposed forwardly of the tubular
wall 32 and which is brought to abut against the tubular
edge surface 322 so as to ensure fluid-tight engagement of
the front seal member 35 with the tubular wall 32. An annular
barrier 36 is disposed to abut against the rear wall end
321 of the carpule 3, and is detachably sleeved on the rear
seal member 34 to serve as the rear annular shoulder. Moreover,
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a sleeve 13 extends rearwardly from the inner peripheral
edge 141 of the front annular shoulder 125 such that the
annular stepped surface 227 of the seat member 22 abuts
against the sleeve 13 in the position of use.
Referring to Figs. 12 to 14, the third preferred
embodiment of a disposable syringe according to this
invention is shown to be similar to the first embodiment
in construction. In the third embodiment, the barrel 1 has
a tubular front wall 129 which extends forwardly from the
rear wall portion 123 in the axial direction and which is
spaced apart from the front wall portion 124 in radial
directions to define a sliding channel 120 therebetween.
A tubular touching member 16 is received in the sliding
channel 120, and includes a tubular touching wall which
surrounds the axis, and which has a rear engaging end 162
that is slidably engaged with the front wall portion 124,
and a front touching end 161 that is movable by virtue of
a sliding movement of the rear engaging end 162 between a
forward position, where the touching end 161 is disposed
forwardly of the tip end 232 of the needle cannula 23 for
touching a patient' s skin prior to piercing of the skin with
the tip end 232, and a rearward position, where the touching
end 161 is retracted to expose the tip end 232 for a piercing
action. The front touching end 161 has a rough surface. The
needle protector 25 removably covers the tubular front wall
129 so as to shield the needle cannula 23 before use.
During the injection stroke, the front touching end 161
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is brought to touch a patient's skin and is forced to move
rearwardly to the rearward position to expose the tip end
232 of the needle cannula 23 for the piercing action. When
the touching member 16 comes into contact with the patient' s
skin, the patient's attention to the needle cannula 23 is
diverted thereto, thereby minimizing the injection pain.
Referring to Fig. 15, the fourth preferred embodiment
of a disposable syringe according to this invention is shown
to be similar to the third embodiment in construction. In
thefourth embodiment, the syringe f urther comprises a spring
17 which is disposed in the sliding channel 120 to bias the
touching end 161 of the touching member 16 to the forward
position.
Referring to Fig. 16, the fifth preferred embodiment
of a disposable syringe according to this invention is shown
to be similar to the fourth embodiment in construction. In
the fifth embodiment, the front seal member 35 has an annular
flange 353 which is disposed forwardly of the tubular wall
32 and which is brought to abut against the tubular edge
surface 322 so as to ensure fluid-tight engagement between
the front seal member 35 and the tubular wall 32. An annular
barrier 36 is disposed to abut against the rear wall end
321 of the carpule 3, and is detachably sleeved on the rear
seal member 34 to serve as the rear annular shoulder.
Referring to Fig. 17, the sixth preferred embodiment
of a disposable syringe according to this invention is shown
to be similar to the fourth embodiment in construction. In
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the sixth embodiment, the tubularmount 226of the seatmember
22 extends through the front compartment (lla) to abut
against the front barrel end 122. The barrel 1 has a tubular
spacer 18 which is integrally formed with and which extends
rearwardly from the front annular shoulder 125 to permit
abutment of the front abutment surface 223 of the seat member
22 thereagainst, and which encloses the lower end 242 of
the biasing member 24 for steadying the biasing action of
the biasing member 24.
Referring to Fig. 18, the seventh preferred embodiment
of a disposable syringe according to this invention is shown
to be similar to the sixth embodiment in construction. In
the seventh embodiment, the carpule 3 is the same as that
of the second embodiment. The surrounding front abutment
surface 223 of the seat member 22 is disposed to be spaced
apart from the fins 14 of the front annular shoulder 125
so as to expose the lower end 242 of the biasing member 24.
Thus, the tubular spacer 18 is omitted, and the biasing member
24 may have a larger dimension to enhance the biasing strength
thereof.
Referring to Figs. 19 and 20, the eighth preferred
embodiment of a disposable syringe according to this
invention is shown to be similar to the third embodiment
in construction. In the eighth embodiment, the carpule 3
has an annular keyslot 37 which is disposed adjacent to the
tubular edge surface 322 and which extends in the axial
direction to surround the front seal member 35. The seat
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member 22 has an annular key 224 which extends rearwardly
from the gripped portion 222 and which is disposed to slide
in and along the keyslot 37 for facilitating a forward
movement of the carpule 3 along the axis when the seat member
22 is brought to the disengaging position. Besides, the
engagement of the keyslot 37 with the key 224 facilitates
rearward movement of the seat member 22 together with the
carpule 3 toward the rear barrel end 121 so as to ensure
retraction of the needle cannula 23 to the disposal position.
By means of the provision of the keyslot 37 and the key 224,
the carpule 3 can be firmly received in the rear compartment
(llb), thereby preventing the communicating end 231 from
accidentally piercing the front seal member 35 during
transport.
Referring to Fig. 21, the ninth preferred embodiment
of a disposable syringe according to this invention is shown
to be similar to the eighth embodiment in construction,
except that the barrel 1 is the same as that of the first
embodiment.
Referring to Figs. 22 and 23, the tenth preferred
embodiment of a disposable syringe according to this
invention is shown to be similar to the first embodiment
in construction. In the tenth embodiment, the barrel 1 has
two parts. Particularly, the rear wall portion 123 of the
barrel wall 12 includes a first wall segment (123a) which
is integrally formed with and which extends rearwardly from
the front wall portion 124 to receive the seat member 22
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and the grip member 21 as a first unit, and a second wall
segment (123b) which is threadedly engaged with the first
wall segment (123a) to receive the carpule 3 and the plunger
4 as a second unit. A first end cap 6 is threadedly connected
5 to the first wall segment (123a) for shielding the
communicating end 231 of the needle cannula 23. A second
end cap 7 is threadedly connected to the second wall segment
(123b) for shielding the carpule 3. Thus, the first and second
units can be packed separately to meet a variety of inj ection
10 requirements.
Referring to Fig. 24, the eleventh preferred embodiment
of a disposable syringe according to this invention is shown
to be similar to the tenth embodiment in construction, except
that the seat member 22 and the carpule 3 are the same as
15 those of the ninth embodiment.
Referring to Fig. 25, the twelfth preferred embodiment
of a disposable syringe according to this invention is shown
to be similar to the tenth embodiment in construction, except
that the front wall portion 124 of the barrel 1, the tubular
20 touching member 16, and the spring 17 are the same as those
of the fourth embodiment.
Referring to Figs. 26 and 27, the thirteenth preferred
embodiment of a disposable syringe according to this
invention is shown to be similar to the first embodiment
in construction. In the thirteenth embodiment, the front
seal member 325 of the carpule 3 is integrally formed with
the tubular wall 32. Instead of the seat member 22 which
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holds the needle cannula 23, the carpule 3 has a tubular
needle holding portion 327 which extends forwardly from the
mating surface 326 along the axis and which holds the
communicating end 231 of the needle cannula 23 to communicate
the needle cannula 23 with the sealed chamber 31. The carpule
3 further has an annular keyslot 37 which extends forwardly
fromthemating surface 326 in the axial direction to surround
the needle holding portion 327. The seat member 22 has an
annular key 224 which extends rearwardly from the gripped
portion 222 and which is disposed to slide in and along the
keyslot 37. Moreover, an elastomeric packing 26 is stuffed
in the tip protector 25 such that when the tip protector
25 is sleeved on the barrel wall 12, the tip end 232 of the
needle cannula 23 is trapped in the elastomeric packing 26,
thereby preventing fluid leakage.
Referringto Fig. 28, the fourteenth preferred embodiment
of a disposable syringe according to this invention is shown
to be similar to the thirteenth embodiment in construction,
except that the barrel 1 and the tubular touching member
16 are the same as those of the third embodiment.
As illustrated, the disposable syringe of this invention
has the following advantages:
1. Since the communicating end 231 of the needle cannula
23 is held by the carpule 3 after the carpule 3 is mounted
in the barrel 1, and since the seat member 22 is mated with
the front seal member 35, 325 when the seat member 22 is in
the disengaging position, the seat member 22 can be moved
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together with the carpule 3 towards the rear barrel end 121
by the biasing action of the biasing member 24 in the needle
retraction stroke, thereby ensuring the retraction of the
needle cannula 23 into the barrel 1.
2. Since the carpule 3 can be pre-assembled in the barrel
1, clinical injection operation by health care workers is
simplified and convenient to conduct. In addition, the
syringe can be conveniently rendered unreusable after
injection in a single operation.
3. Since, the resisting force generated between the grip
member 21 and the seat member 22, and the frictional force
generated between the first and second plunger bodies43,41
during pressing of the plunger 4 are overcome by the external
pressing force, the injection and needle retraction strokes
are smooth and successful.
4. Since the operating end 42 of the plunger 4 is retained
with the retaining portion 12 6 of the barrel 1 to guard against
a rearward movement of the plunger 4 after the operating
end 42 is fully pressed in the barrel 1, reuse of the syringe
can be prevented.
While the present invention has been described in
connection with what are considered the most practical and
preferred embodiments, it is understood that this invention
is not limited to the disclosed embodiments but is intended
to cover various arrangements included wit.hin the spirit
and scope of the broadest interpretations and equivalent
arrangements.
