U.S. patent application number 11/387625 was filed with the patent office on 2006-11-23 for syringe.
Invention is credited to Daniel Thayer.
Application Number | 20060264840 11/387625 |
Document ID | / |
Family ID | 37397026 |
Filed Date | 2006-11-23 |
United States Patent
Application |
20060264840 |
Kind Code |
A1 |
Thayer; Daniel |
November 23, 2006 |
Syringe
Abstract
A retractable needle safety syringe is provided having mitigated
retraction. The syringe comprises a syringe body, a syringe cavity,
a plunger, a variable vacuum compartment, a shaft brake, and a ram
member. The plunger assembly includes a plunger shaft and a piston
slidably engaged within the syringe body. The variable vacuum
compartment is disposed within the syringe cavity and provides a
vacuum force on the plunger shaft directed from a bottom syringe
body end toward a top syringe body end. The shaft brake, being
attached to the top syringe body end, may frictionally engage the
plunger shaft to provide first and second frictional forces in
opposition to the vacuum force, the first frictional force being
exerted prior to the piston reaching the bottom syringe body end,
the second frictional force being exerted in response to the
engagement of the ram member with the shaft brake.
Inventors: |
Thayer; Daniel; (Mission
Viejo, CA) |
Correspondence
Address: |
STETINA BRUNDA GARRED & BRUCKER
75 ENTERPRISE, SUITE 250
ALISO VIEJO
CA
92656
US
|
Family ID: |
37397026 |
Appl. No.: |
11/387625 |
Filed: |
March 23, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60679113 |
May 9, 2005 |
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Current U.S.
Class: |
604/218 |
Current CPC
Class: |
A61M 5/3234 20130101;
A61M 2005/3242 20130101; A61M 2005/3151 20130101 |
Class at
Publication: |
604/218 |
International
Class: |
A61M 5/315 20060101
A61M005/315 |
Claims
1. A retractable needle safety syringe with mitigated retraction,
the syringe comprising: a syringe body defining opposing top and
bottom syringe body ends and including a syringe cavity; an
attachment seal defining a shaft orifice and being attached to the
top syringe body end; a plunger assembly including a plunger shaft
and a piston, the plunger shaft defining opposing top and bottom
shaft ends, the plunger shaft being disposed through the shaft
orifice in the syringe cavity, the piston being disposed at the
bottom shaft end, the plunger being slidably engaged with the
syringe body within the syringe cavity; a variable vacuum
compartment being disposed within the syringe cavity between the
piston and the attachment seal, the variable vacuum compartment
being operative to provide a vacuum force on the plunger shaft
directed from the bottom syringe body end toward the top syringe
body end with the vacuum force increasing upon movement of the
piston toward the bottom syringe body end; a shaft brake being
attached to the top syringe body end and being operative to
frictionally engage the plunger shaft to provide first and second
frictional forces in opposition to the vacuum force, the first
frictional force being exerted upon the plunger shaft prior to the
piston reaching the bottom syringe body end; and a ram member being
attached to the top shaft end and being formed to engage the shaft
brake upon the piston reaching the bottom syringe body end, the
shaft brake exerting the second frictional force upon the plunger
shaft in response to the engagement of the ram member with the
shaft brake, the second frictional force being less than the first
frictional force.
2. The syringe of claim 1 wherein the first frictional force has an
associated first normal force.
3. The syringe of claim 1 wherein the second frictional force has
an associated second normal force.
4. The syringe of claim 1 wherein the shaft brake substantially
disengages from the plunger shaft upon engagement of the ram member
with the shaft brake.
5. The syringe of claim 1 wherein the shaft brake defines a body
perimeter and includes an aperture and a bridge, the aperture being
disposed within the shaft brake and frictionally engaging the
plunger shaft, the bridge defining a bridge width and extending
radially from the aperture toward the body perimeter, the shaft
brake being operative to exert the second frictional force upon the
plunger shaft in response to an increase in bridge width, the
bridge width increasing in response to the engagement of the ram
member with the shaft brake.
6. The syringe of claim 5 wherein the ram member at least partially
severs the bridge to increase the bridge width.
7. The syringe of claim 5 wherein the shaft brake further includes
a release member being disposed upon the shaft brake, the bridge
width increasing in response to the engagement of the ram member
with the release member.
8. The syringe of claim 7 wherein the release member is a shoulder
protruding upwardly from the shaft brake opposite the syringe body,
and the ram member includes a shoulder press being sized and
configured to engage the shoulder upon the piston approaching the
bottom syringe body end, the bridge width increasing in response to
the engagement of the shoulder press with the shoulder.
9. The syringe of claim 8 wherein the bridge width increases upon
deformation of the bridge in response to engagement of the shoulder
press with the shoulder and continued movement of the piston toward
the bottom syringe body end.
10. The syringe of claim 8 wherein the brake body defines a body
thickness and the bridge defines a bridge thickness, the bridge
thickness being less than the body thickness, the bridge being
operative to deform in response to the engagement of the shoulder
press with the shoulder.
11. The syringe of claim 7 wherein the bridge comprises a
non-continuous slit including a hinge element, and the bridge width
increases upon deformation of the hinge element in response to
engagement of the shoulder press with the shoulder and continued
movement of the piston toward the bottom syringe body end.
12. The syringe of claim 1 wherein the shaft brake is formed to
include an anchor member being disposed upon the shaft brake, the
anchor member being operative to mechanically couple the shaft
brake to the attachment seal.
13. The syringe of claim 1 further including a needle being
removably mounted to the bottom syringe body end and extending
therefrom opposite the top syringe body end, the piston including a
punch to engage the needle upon the piston reaching the bottom
syringe body end, the piston being operative to remove the needle
into the syringe cavity upon exertion of the vacuum force upon the
plunger shaft.
14. A method of mitigating retraction of a retractable needle
safety syringe, the syringe comprising a syringe body, an
attachment seal, a plunger assembly, a variable vacuum compartment,
a shaft brake, and a ram member, the syringe body defining opposing
top and bottom syringe body ends and including a syringe cavity,
the attachment seal defining a shaft orifice and being attached to
the top syringe body end, the plunger assembly including a plunger
shaft and a piston, the plunger shaft defining opposing top and
bottom shaft ends, the plunger shaft being disposed through the
shaft orifice in the syringe cavity, the piston being disposed at
the bottom shaft end, the plunger being slidably engaged with the
syringe body within the syringe cavity, the variable vacuum
compartment being disposed within the syringe cavity between the
piston and the attachment seal, the variable vacuum compartment
being operative to provide a vacuum force on the plunger shaft
directed from the bottom syringe body end toward the top syringe
body end with the vacuum force increasing upon movement of the
piston toward the bottom syringe body end, the shaft brake being
attached to the top syringe body end and being operative to
frictionally engage the plunger shaft to provide first and second
frictional forces in opposition to the vacuum force, the first
frictional force being exerted upon the plunger shaft prior to the
piston reaching the bottom syringe body end, the ram member being
attached to the top shaft end and being formed to engage the shaft
brake upon the piston reaching the bottom syringe body end, the
shaft brake exerting the second frictional force upon the plunger
shaft in response to the engagement of the ram member with the
shaft brake, the second frictional force being less than the first
frictional force, the method comprising: a. exerting the first
frictional force upon the plunger shaft in opposition to the vacuum
force prior to the piston reaching the bottom syringe body end; b.
engaging the ram member with the shaft brake; and c. exerting the
second frictional force upon the plunger shaft in opposition to the
vacuum force in response to the engagement of the ram member with
the shaft brake.
15. The method of claim 14 wherein the shaft brake defines a body
perimeter and includes an aperture and a bridge, the aperture being
disposed within the shaft brake and being operative to frictionally
engage the plunger shaft, the bridge defining a bridge width and
extending radially from the aperture toward the body perimeter, the
shaft brake being operative to exert the second frictional force
upon the plunger shaft in response to an increase in bridge width,
the bridge width increasing in response to the engagement of the
ram member with the shaft brake, and step (b) of the method further
includes: a. increasing the bridge width in response to the
engagement of the ram member with the shaft brake.
16. The method of claim 14 wherein step (b) further includes: a.
severing the bridge in response to the engagement of the ram member
with the shaft brake.
17. The method of claim 14 wherein the shaft brake further includes
a shoulder being disposed upon the shaft brake and protruding
upwardly from the shaft brake opposite the syringe body, and the
ram member includes a shoulder press being sized and configured to
engage the shoulder upon the piston approaching the bottom syringe
body end, the bridge width increasing in response to the engagement
of the shoulder press with the shoulder, and step (b) of the method
further includes: a. engaging the shoulder press with the shoulder;
and b. deforming the bridge to increase the bridge width.
18. The method of claim 14 wherein the syringe further includes a
needle being removably mounted to the bottom syringe body end and
extending therefrom opposite the top syringe body end, the piston
including a punch to engage the needle upon the piston reaching the
bottom syringe body end, the piston being operative to remove the
needle into the syringe cavity upon exertion of the vacuum force
upon the plunger shaft, the method further including the steps of:
a. engaging the needle with the punch; and b. automatically
removing the needle into the syringe cavity.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/679,113 entitled "IMPROVED SYRINGE" filed May 9,
2005, the entirety of the disclosure of which is expressly
incorporated herein by reference.
STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT
[0002] Not Applicable
BACKGROUND OF THE INVENTION
[0003] The risks associated with the spread of blood-borne
pathogens through use of hypodermic needles are significant and
well documented. In recent years, the public has become
increasingly aware of the health hazards associated with needle
reuse and accidental needle prickings. These risks are most
prevalent among certain groups of people, such as drug addicts,
drug users (e.g., diabetics), medical personnel and healthcare
providers. In fact, more than twenty blood-borne pathogens can be
transmitted by the reuse of needles or accidental needle prickings,
just a few of which include human immunodeficiency virus (HIV),
acquired immunodeficiency syndrome (AIDS), hepatitis B, hepatitis
C, syphilis, malaria, tuberculosis, and herpes.
[0004] In 1997, the Centers for Disease Control and Prevention
(CDC) sponsored a study which found that approximately 76% of
needle pricking injuries could be avoided by using safety needles.
As a result, needle legislation has now been introduced in
approximately twenty-five states and in the District of Columbia.
In fact, such safety needle legislation has already been signed
into law in a number of states including California, Texas,
Tennessee, New Jersey and Maryland. In addition, the Occupational
Safety and Health Administration (OSHA) has promulgated a
Blood-borne Pathogens Standard requiring employers to evaluate the
effectiveness of existing controls designed to minimize or
eliminate employee occupational exposure and to review the
feasibility of instituting more advanced controls. Furthermore, the
Food and Drug Administration (FDA), in an effort to protect health
care workers, has set forth guidelines suggesting specific features
that a safety syringe should possess. These include a safety
feature that is not only simple and self evident to operate, thus
requiring little or no additional training to use effectively, but
also a safety feature that is an integral part of the apparatus. In
other words, the guidelines suggest that the safety feature itself
be unremovable and utilization of the safety feature be
unavoidable. (www.osha-slc.gov/SLTC/needle
stick/saferneedledevices/saferneedledevices.html;
www.seiu.org).
[0005] As a result of the foregoing state legislation and agency
guidelines, a great amount of time, effort and money has been
invested by syringe manufacturers in developing syringes with
safety needle designs. Presently, there are at least 250 types of
safety syringes. However, the safety syringes that currently exist
have been criticized for generally being too expensive to
manufacture and having a safety feature that is not an integral
part of the safety syringe. Another criticism includes safety
syringes that are not economically feasible because operation of
the safety feature is not self evident and therefore additional
training is required to use the apparatus effectively.
Additionally, the safety feature of at least one safety syringe is
simply ineffective at preventing the transmission of blood-borne
pathogens due to "reflux" blood contamination.
[0006] Of the current safety syringes, safety syringes using a
spring mechanism are the most common for automatically retracting a
hollow needle after injecting a fluid. However, these safety
syringes are typically more expensive because of the required
incorporation of additional materials for manufacture. Standard or
conventional hypodermic needle syringes typically cost from five to
seven cents each. On the other hand, the median increase in cost
for a safety syringe is approximately thirty cents or more. At
first glance, this minimal cost increase does not seem significant.
However, after considering the thousands, if not millions, of
needles used each year, the resultant increase in annual cost for
utilizing the more expensive safety syringe is unfortunately
excessive.
[0007] Another syringe has been created that avoids some of the
additional cost associated with spring mechanism safety syringes.
This syringe, found in U.S. Pat. No. 6,413,236, entitled
"Automatically Retractable Needle Safety Syringe," issued on Jul.
2, 2002, seeks to solve the problem of needle reuse and accidental
needle prickings through use of a vacuum. As disclosed therein, the
safety syringe is configured to automatically retract the needle
portion of the syringe into the body of the syringe utilizing a
vacuum within the syringe, such that after a single use, the
syringe may not be reusable nor lead to an accidental pricking.
[0008] As understood, the syringe of U.S. Pat. No. 6,413,236
utilizes vacuum pressure to exert an automatic retracting force
upon the needle. Apparently, the syringe includes a plunger and a
needle body (to which the needle is attached) and is configured to
frictionally engage the plunger with the needle body. Once engaged
with the needle body, the vacuum pressure inside the syringe exerts
the retracting force upon the plunger, which causes the plunger to
remove the needle body and pull it into the syringe itself. After
being completely retracted, the needle does not protrude and the
syringe cannot be reused nor accidentally prick an individual.
[0009] The aforementioned retractable safety syringes have helped
alleviate many of the problems associated with accidental needle
prickings and reuse of hypodermic needles. However, due to the
configuration and retraction force inherent in the vacuum or spring
mechanism aspect of these syringes and others like them, the user
of the syringe may often experience difficulties in its use.
Specifically, due to the vacuum pressure or spring mechanism, which
exerts an automatic retracting force upon the plunger, the plunger
may automatically retract at an undesirable time.
[0010] It is an apparent object of these syringes to retract the
plunger when the needle body has been frictionally engaged with the
plunger. However, automatic retraction of the plunger prior to
frictional engagement with the needle body may often be very
problematic. For example, automatic retraction may make syringe
handling very difficult between the time the fluid is drawn to the
time the fluid is emptied. In effect, a user must manually maintain
the position of the plunger by exerting a force to counter the
automatic retracting force. Otherwise, the plunger will retract.
Retraction of the plunger may be a nuisance if the syringe has not
been introduced into the subject. However, while the needle is
introduced into the subject, retraction of the plunger could
effectively result in drawing fluid therefrom instead of the
intended injection of fluid into the subject. This situation could
be very harmful and lead to various unfortunate consequences.
[0011] Therefore, a need exists for an effective and efficient,
inexpensive safety syringe that is simple and self evident to
operate and integrally comprises a safety feature having a hollow
needle that protectively retracts automatically after a single
injection, but that mitigates against automatic retraction of the
needle prior to completion of use. Further, there is a need in the
art for an automatically retractable safety syringe that mitigates
against automatic retraction of the needle during administration of
the fluid injected therewith.
BRIEF SUMMARY OF THE INVENTION
[0012] In accordance with an embodiment of the present invention, a
retractable needle safety syringe is provided with mitigated
retraction. The syringe comprises a syringe body defining opposing
top and bottom syringe body ends and including a syringe cavity; an
attachment seal defining a shaft orifice and being attached to the
top syringe body end; a plunger assembly including a plunger shaft
and a piston, the plunger shaft defining opposing top and bottom
shaft ends, the plunger shaft being disposed through the shaft
orifice in the syringe cavity, the piston being disposed at the
bottom shaft end, the plunger being slidably engaged with the
syringe body within the syringe cavity; a variable vacuum
compartment being disposed within the syringe cavity between the
piston and the attachment seal, the variable vacuum compartment
being operative to provide a vacuum force on the plunger shaft
directed from the bottom syringe body end toward the top syringe
body end with the vacuum force increasing upon movement of the
piston toward the bottom syringe body end; a shaft brake being
attached to the top syringe body end and being operative to
frictionally engage the plunger shaft to provide first and second
frictional forces in opposition to the vacuum force, the first
frictional force being exerted upon the plunger shaft prior to the
piston reaching the bottom syringe body end; and a ram member being
attached to the top shaft end and being formed to engage the shaft
brake upon the piston reaching the bottom syringe body end, the
shaft brake exerting the second frictional force upon the plunger
shaft in response to the engagement of the ram member with the
shaft brake, the second frictional force being less than the first
frictional force.
[0013] The first frictional force may have an associated first
normal force. The second frictional force may have an associated
second normal force. Additionally, the shaft brake substantially
disengages from the plunger shaft upon engagement of the ram member
with the shaft brake.
[0014] The shaft brake may define a body perimeter and include an
aperture and a bridge, the aperture being disposed within the shaft
brake and frictionally engaging the plunger shaft, the bridge
defining a bridge width and extending radially from the aperture
toward the body perimeter, the shaft brake being operative to exert
the second frictional force upon the plunger shaft in response to
an increase in bridge width, the bridge width increasing in
response to the engagement of the ram member with the shaft brake.
The ram member may at least partially sever the bridge to increase
the bridge width.
[0015] The shaft brake may further include a release member being
disposed upon the shaft brake, the bridge width increasing in
response to the engagement of the ram member with the release
member. The release member may be a shoulder protruding upwardly
from the shaft brake opposite the syringe body, and the ram member
includes a shoulder press being sized and configured to engage the
shoulder upon the piston approaching the bottom syringe body end,
the bridge width increasing in response to the engagement of the
shoulder press with the shoulder. The bridge width may increase
upon deformation of the bridge in response to engagement of the
shoulder press with the shoulder and continued movement of the
piston toward the bottom syringe body end.
[0016] The brake body may define a body thickness and the bridge
may define a bridge thickness, the bridge thickness being less than
the body thickness, the bridge being operative to deform in
response to the engagement of the shoulder press with the shoulder.
The bridge may comprise a non-continuous slit including a hinge
element, and the bridge width may increase upon deformation of the
hinge element in response to engagement of the shoulder press with
the shoulder and continued movement of the piston toward the bottom
syringe body end.
[0017] The shaft brake may be formed to include an anchor member
being disposed upon the shaft brake, the anchor member being
operative to mechanically couple the shaft brake to the attachment
seal. The syringe may further include a needle being removably
mounted to the bottom syringe body end and extending therefrom
opposite the top syringe body end, the piston including a punch to
engage the needle upon the piston reaching the bottom syringe body
end, the piston being operative to remove the needle into the
syringe cavity upon exertion of the vacuum force upon the plunger
shaft.
[0018] In accordance with another embodiment of the present
invention, a method is provided of mitigating retraction of a
retractable needle safety syringe. The syringe comprises a syringe
body, an attachment seal, a plunger assembly, a variable vacuum
compartment, a shaft brake, and a ram member, the syringe body
defining opposing top and bottom syringe body ends and including a
syringe cavity, the attachment seal defining a shaft orifice and
being attached to the top syringe body end, the plunger assembly
including a plunger shaft and a piston, the plunger shaft defining
opposing top and bottom shaft ends, the plunger shaft being
disposed through the shaft orifice in the syringe cavity, the
piston being disposed at the bottom shaft end, the plunger being
slidably engaged with the syringe body within the syringe cavity,
the variable vacuum compartment being disposed within the syringe
cavity between the piston and the attachment seal, the variable
vacuum compartment being operative to provide a vacuum force on the
plunger shaft directed from the bottom syringe body end toward the
top syringe body end with the vacuum force increasing upon movement
of the piston toward the bottom syringe body end, the shaft brake
being attached to the top syringe body end and being operative to
frictionally engage the plunger shaft to provide first and second
frictional forces in opposition to the vacuum force, the first
frictional force being exerted upon the plunger shaft prior to the
piston reaching the bottom syringe body end, the ram member being
attached to the top shaft end and being formed to engage the shaft
brake upon the piston reaching the bottom syringe body end, the
shaft brake exerting the second frictional force upon the plunger
shaft in response to the engagement of the ram member with the
shaft brake, the second frictional force being less than the first
frictional force. The method comprises: (a) exerting the first
frictional force upon the plunger shaft in opposition to the vacuum
force prior to the piston reaching the bottom syringe body end; (b)
engaging the ram member with the shaft brake; and (c) exerting the
second frictional force upon the plunger shaft in opposition to the
vacuum force in response to the engagement of the ram member with
the shaft brake.
[0019] According to another implementation of the method, the shaft
brake defines a body perimeter and includes an aperture and a
bridge, the aperture being disposed within the shaft brake and
being operative to frictionally engage the plunger shaft, the
bridge defining a bridge width and extending radially from the
aperture toward the body perimeter, the shaft brake being operative
to exert the second frictional force upon the plunger shaft in
response to an increase in bridge width, the bridge width
increasing in response to the engagement of the ram member with the
shaft brake, and step (b) of the method may further include:
increasing the bridge width in response to the engagement of the
ram member with the shaft brake.
[0020] In accordance with yet another implementation of the method,
step (b) may further include: severing the bridge in response to
the engagement of the ram member with the shaft brake.
[0021] In accordance with yet another implementation of the method,
the shaft brake further includes a shoulder being disposed upon the
shaft brake and protruding upwardly from the shaft brake opposite
the syringe body, and the ram member includes a shoulder press
being sized and configured to engage the shoulder upon the piston
approaching the bottom syringe body end, the bridge width
increasing in response to the engagement of the shoulder press with
the shoulder, and step (b) of the method may further include:
engaging the shoulder press with the shoulder; and deforming the
bridge to increase the bridge width.
[0022] In accordance with yet another implementation of the method,
the syringe further includes a needle being removably mounted to
the bottom syringe body end and extending therefrom opposite the
top syringe body end, the piston including a punch to engage the
needle upon the piston reaching the bottom syringe body end, the
piston being operative to remove the needle into the syringe cavity
upon exertion of the vacuum force upon the plunger shaft, and the
method may further include the steps of: engaging the needle with
the punch; and automatically removing the needle into the syringe
cavity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] An illustrative and presently preferred embodiment of the
invention is shown in the accompanying drawings in which:
[0024] FIG. 1 a cross sectional view of a retractable needle safety
syringe with mitigated retraction in accordance with an aspect of
the present invention;
[0025] FIG. 2 is a cross sectional view of the syringe illustrating
the interaction between a ram member and a shaft brake;
[0026] FIG. 3 is a top plan view of the shaft brake in accordance
with another embodiment of the present invention;
[0027] FIG. 4 is a side view of the shaft brake in accordance with
another embodiment of the present invention; and
[0028] FIG. 5 is a top plan view of the shaft brake in accordance
with another embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0029] Referring now to the drawings wherein the showings are for
purposes of illustrating the preferred embodiments of the present
invention only and not for purposes of limiting the same, FIG. 1 is
a cross sectional view of a retractable needle safety syringe 10
with mitigated retraction in accordance with an aspect of the
present invention.
[0030] An embodiment of the syringe comprises a syringe body 12, an
attachment seal 14, a plunger assembly 16, a variable vacuum
compartment 18, a shaft brake 20, and a ram member 22. The syringe
body 12 defines opposing top and bottom syringe body ends 24, 26
and includes a syringe cavity 28. The attachment seal 14 defines a
shaft orifice 30 and is attached to the top syringe body end 24.
The plunger assembly 16 includes a plunger shaft 32 and a piston
34. The plunger shaft 32 defines opposing top and bottom shaft ends
36, 38. The plunger shaft 32 is disposed throughout the shaft
orifice 30 in the syringe cavity 28. The piston 34 is disposed at
the bottom shaft end 38. The plunger is slidably engaged with the
syringe body 12 within the syringe cavity 28. The variable vacuum
compartment 18 is disposed within the syringe cavity 28 between the
piston 34 and the attachment seal 14. The variable vacuum
compartment 18 is operative to provide a vacuum force 40 on the
plunger shaft 32 directed from the bottom syringe body end 26
toward the top syringe body end 24 with the vacuum force 40
increasing upon movement of the piston 34 toward the bottom syringe
body end 26. The shaft brake 20 is attached to the top syringe body
end 24 and is operative to frictionally engage the plunger shaft 32
to provide first and second frictional forces 42, 44 in opposition
to the vacuum force 40. The first frictional force 42 is exerted
upon the plunger shaft 32 prior to the piston 34 reaching the
bottom syringe body end 26. The ram member 22 is attached to the
top shaft end 36 and is formed to engage the shaft brake 20 upon
the piston 34 reaching the bottom syringe body end 26. The shaft
brake 20 exerts the second frictional force 44 upon the plunger
shaft 32 in response to the engagement of the ram member 22 with
the shaft brake 20. The second frictional force 44 is less than the
first frictional force 42.
[0031] As illustrated in FIG. 1, the syringe may further include a
needle 46 being removably mounted to the bottom syringe body end 26
and extending therefrom opposite the top syringe body end 24. The
piston 34 may include a punch 48 to engage the needle 46 upon the
piston 34 reaching the bottom syringe body end 26. The piston 34
may be operative to remove the needle 46 into the syringe cavity 28
upon exertion of the vacuum force 40 upon the plunger shaft 32. The
needle 46 may be attached to the bottom syringe body end 26 via a
needle body 50. The punch 48 may engage the needle body 50 of the
needle 46 upon the piston 34 reaching the bottom syringe body end
26.
[0032] As will be appreciated by one of skill in the art, in order
to effectuate an intake of fluid into the syringe cavity 28 of the
syringe body 12, a thumb platform 52 of the plunger should first be
depressed by thrusting the thumb platform 52 toward the syringe
body 12 to remove a majority of the air present within the syringe
cavity 28 between the bottom syringe body end 26 and the piston 34.
During this depression, the piston 34 of the plunger assembly 16 is
forced to slide within the syringe cavity 28 toward the bottom
syringe body end 26. The attachment seal 14 and the piston 34 are
substantially air tight and fluid tight. Therefore, a corresponding
influx of air molecules and fluid molecules into the variable
vacuum compartment 18 of the syringe body 12 is prevented. As a
result, the volume within the variable vacuum compartment 18 is
increased without a corresponding influx of air molecules or fluid
molecules therefore creating a vacuum within the variable vacuum
compartment 18. In order to complete the intake of fluid into the
syringe cavity 28, while the thumb platform 52 remains forcibly
depressed, a piercing tip end 54 of the needle 46 is submerged into
a fluid present within a fluid container. Once the piercing tip end
54 is submerged within the fluid, the thumb platform 52 is allowed
to move, as a result of the vacuum created within the variable
vacuum compartment 18 and a decrease in the forcible depression,
away from the syringe body 12 thus effectuating a withdraw of a
desired amount of fluid from a fluid container into the syringe
cavity 28.
[0033] In order to inject the fluid and retract the needle 46 into
the syringe body 12, the operation of the syringe may be as
follows. The piercing tip of the needle 46 may be inserted into a
patient or other instrument wherein the fluid is to be injected.
Upon depressing the thumb platform 52, the fluid may be evacuated
from the syringe cavity 28 and injected. During this injection
stroke, a vacuum may be created within the variable vacuum
compartment 18 as a result of an increase in volume within the
variable vacuum compartment 18 without a corresponding influx of
air molecules due to the attachment seal 14 and the piston 34
creating an air tight and fluid tight seal, as mentioned above. At
the end of the injection stroke, as the piston 34 reaches the
bottom syringe body end 26, the punch 48 may frictionally engage
the needle body 50. Due to the vacuum force 40, the needle 46 may
immediately and automatically be withdrawn within the syringe
cavity 28 such that the entire needle 46 permanently resides
enclosed within and protectively pressed against the syringe cavity
28. This alleviates needle 46 reuse and accidental needle 46
prickings and, therefore, ultimately prevents the transmission of
blood born pathogens and other diseases by contaminated syringe
needles 46.
[0034] As mentioned above, when the variable vacuum compartment 18
is enlarged upon movement of the piston 34 toward the bottom
syringe body end 26, the vacuum created within the variable vacuum
compartment 18 may exert a vacuum force 40 upon the plunger shaft
32. As will be understood by one of skill, the vacuum force 40 may
be exerted upon the plunger shaft 32 indirectly via exertion upon
the piston 34. The vacuum force 40 may vary as the piston 34 moves
toward the bottom syringe body end 26 or toward the top syringe
body end 24. Thus, the vacuum force 40 may increase or decrease,
respectively. The vacuum force 40 may be exerted on the plunger
shaft 32 directed from the bottom syringe body end 26 toward the
top syringe body end 24. The vacuum force 40, as disclosed in an
embodiment of the present invention, may be caused due to a vacuum
pressure in the variable vacuum compartment 18. However, in
accordance with another aspect of the present invention, the vacuum
force 40 may also be produced due to a spring mechanism that is
housed in the variable vacuum compartment 18. The vacuum force 40
therefore need not be produced only due to the vacuum within the
variable vacuum compartment 18. In this regard, it is also
contemplated that the variable vacuum compartment 18 need not be
air tight when such a spring mechanism is used therein to produce
the vacuum force 40.
[0035] According to an aspect of the present invention, the shaft
brake 20 is attached to the top syringe body end 24 and is
operative to frictionally engage the plunger shaft 32 to provide
the first frictional force 42 in opposition to the vacuum force 40.
The first frictional force 42 may be exerted upon the plunger shaft
32 prior to the piston 34 reaching the bottom syringe body end 26.
Nevertheless, in accordance with an aspect of the present
invention, the first frictional force 42 may be exerted upon the
plunger shaft 32 even after the piston 34 has reached the bottom
syringe body end 26. For example, as mentioned above, in order to
intake fluid in preparation for an injection, the first frictional
force 42 may be continuously exerted upon the piston 34 shaft as
the piston 34 moves toward and away from the bottom syringe body
end 26. In this regard, the first frictional force 42 exerted upon
the plunger shaft 32 may be equivalent to or greater than the
vacuum force 40. This advantageous embodiment of the present
invention may provide that the user need not maintain continuous
forcible depression of the thumb platform 52 after intaking fluid
in preparation for the injection. Otherwise, the vacuum force 40
exerted upon the plunger shaft 32 would require the user to either
maintain the thumb platform 52 being depressed or intake air into
the syringe cavity 28. An even more troublesome situation may
resolved with an embodiment of the present invention. If the user
does not maintain the forcible depression of the thumb platform 52
after injection and prior to withdrawal of the piercing tip end 54
from the patient or instrument, the vacuum force 40 may cause
intake of fluids from the patient or instrument. Risks associated
with this type of accident may be alleviated by implementing
aspects of the present invention. As discussed above, continuous
exertion of the first frictional force 42 by the shaft brake 20
upon the plunger shaft 32 may counteract the vacuum force 40 and
help avoid such difficulties of syringe use. Overall, equalization
of the vacuum force 40 by the first frictional force 42 may provide
the user with greater control over intake and injection using the
syringe.
[0036] In accordance with an aspect of the present invention, the
ram member 22 is attached to the top shaft end 36 and is formed to
engage the shaft brake 20 upon the piston 34 reaching the bottom
syringe body end 26. As illustrated in FIGS. 1 and 2, the ram
member 22 may be integrally formed with the thumb platform 52.
Nevertheless, the ram member 22 may be attached and configured as
required in order to provide optimal mechanical engagement with the
shaft brake 20. The engagement of the ram member 22 with the shaft
brake 20 is therefore contemplated to be primarily a mechanical
engagement as shown in FIG. 2. As such, the mechanical engagement
contemplated herein may likely provide a cost effective, efficient
and safe means for releasing the shaft brake 20. It is nevertheless
contemplated that the engagement of the ram member 22 with the
shaft brake 20 may be indirect through other elements, or that the
engagement may be other than mechanical, such as electrical or
chemical. Further, although an embodiment of the ram member 22 is
illustrated herein, the shaft brake 20 may be variously
modified.
[0037] Upon engagement of the ram member 22 with the shaft brake
20, the shaft brake 20 may exert the second frictional force 44
upon the plunger shaft 32. As discussed above, it is contemplated
that the first frictional force 42 may be exerted by the shaft
brake 20 upon the plunger shaft 32 upon the piston 34 moving toward
and away from the bottom syringe body end 26. Thus, although the
piston 34 may approach the bottom syringe body end 26, engagement
may not occur. For example, in an embodiment, the ram member 22 may
be configured to engage the shaft brake 20 only upon the piston 34
being thrusted to the bottom syringe body end 26. In this regard,
it is contemplated that the ram member 22 and the shaft brake 20
may contact each other prior to engagement of the piston 34 with
the shaft brake 20. The engagement process, as contemplated in one
embodiment of the present invention, is depicted in FIG. 2. As
shown therein, the continued movement of the plunger assembly 16
toward the bottom syringe body end 26 may be operative to cause
complete engagement of the ram member 22 with the shaft brake 20.
Certain other advantageous features may also be incorporated into
embodiments of the present invention such as prophylactic measures
to prevent premature engagement. For example, after making the
initial contact, the user may be aware that further displacement of
the piston 34 toward the bottom syringe body end 26 will result in
engagement of the ram member 22 with the shaft brake 20, which may
be accomplished through sound, feel, or other possible indications
from the syringe. Such a prophylactic measure may allow the user to
control the engagement of the ram member 22 with the shaft brake
20, which in turn may coincide with the engagement of the punch 48
with the needle 46 and retraction of the needle 46 into the syringe
cavity 28. Therefore, various designs may be incorporated into
aspects of the present invention to ensure that deliberate
engagement and retraction take place.
[0038] Upon engagement of the ram member 22 with the shaft brake
20, the shaft brake 20 may exert the second frictional force 44
upon the plunger shaft 32. According to an aspect of the present
invention, the second frictional force 44 may be less than the
first frictional force 42. As discussed above, while the first
frictional force 42 may be equivalent to or greater than the vacuum
force 40, it is contemplated that the second frictional force 44
may be less than the vacuum force 40. Therefore, in operation after
the injection stroke, the ram member 22 may engage the shaft brake
20, and simultaneously, the syringe may be configured to engage the
punch 48 with the needle 46. Then, due to the engagement of the ram
member 22 with the shaft brake 20, the first frictional force 42
may be replaced by the second frictional force 44, which may be
less than the vacuum force 40, resulting in substantially
unrestrained retraction of the needle 46 into the syringe cavity
28.
[0039] The first frictional force 42 may have an associated first
normal force 56. The first normal force 56 may therefore be
directly related to the configuration and placement of the shaft
brake 20 about the plunger shaft 32, the pressure exerted thereon
being the first normal force 56. The first normal force 56 may be
increased or decreased according to design requirements. As may be
appreciated by one of skill in the art, the shaft brake 20 and the
first normal force 56 exerted by the shaft brake 20 upon the
plunger shaft 32, may be configured according to user requirements.
As is known in the art, the first frictional force 42 (F.sub.first)
may be represented mathematically as:
F.sub.first=.mu..sub.k/sN.sub.first, where .mu..sub.k/s represents
the coefficient of kinetic/sliding friction, and N.sub.first
represents the first normal force 56. The first normal force 56 may
be exerted in certain embodiments, with the shaft brake 20 entirely
encircling and contacting the plunger shaft 32 about the entire
circumference of the plunger shaft 32. However, in alternative
embodiments, it is contemplated that the first normal force 56 may
be exerted by the shaft brake 20 by contacting only a portion of
the circumference of the plunger shaft 32.
[0040] The second frictional force 44 may have an associated second
normal force 58. Similar to that shown above, the second frictional
force 44 may be calculated using the equation;
F.sub.second=.mu..sub.k/sN.sub.second. The shaft brake 20 may be at
least partially released from the plunger shaft 32 upon engagement
of the ram member 22 with the shaft brake 20 and thus exert the
second frictional force 44, which may be greater than or equal to
zero. In such circumstances where the shaft brake 20 is not
completely disengaged from the plunger shaft 32, the second normal
force 58 may likely be greater than zero, but it is contemplated
that the second normal force 58 may most frequently be less than
the first normal force 56. For example, where the shaft brake 20
substantially disengages from the plunger shaft 32, the second
normal force 58 may be less than or negligible relative to the
first normal force 56, but may be greater than zero.
[0041] According to an aspect of the present invention, it is
contemplated that the shaft brake 20 and the plunger shaft 32 may
be fabricated from various materials. In this regard, the
coefficients of static and kinetic friction may vary depending on
the material from which the shaft brake 20 and the plunger shaft 32
are fabricated. As discussed above, it is contemplated that the
first frictional force 42 may be equivalent to or greater than the
vacuum force 40 during intake of fluid into the syringe. As will be
appreciated by one of skill in the art, a suitable material may be
selected based upon its coefficient of static friction and its
coefficient of kinetic friction in order to facilitate use of the
syringe such as allowing the user to not be required to maintain
depression of the thumb platform 52 during the intake operation.
Other considerations and requirements may also be addressed by
manipulating the characteristics of various materials and their
frictional properties as is known in the art.
[0042] Referring now to FIG. 3, the shaft brake 20 may define a
body perimeter 60 and include an aperture 62 and a bridge 64. The
body perimeter 60 may be generally defined as the outer most
portion of the shaft brake 20. The aperture 62 may be disposed
within the shaft brake 20 and frictionally engage the plunger shaft
32. The bridge 64 may define a bridge width 66 and extend radially
from the aperture 62 toward the body perimeter 60. The shaft brake
20 may be operative to exert the second frictional force 44 upon
the plunger shaft 32 in response to an increase in bridge width 66,
the bridge width 66 increasing in response to the engagement of the
ram member 22 with the shaft brake 20. It is contemplated that
prior to the increase in bridge width 66, the shaft brake 20 may
exert the first frictional force 42 upon the plunger shaft 32, as
discussed above.
[0043] In an embodiment of the present invention, the increase in
bridge width 66 may directly or indirectly cause a corresponding
increase in the size of the aperture 62 of the shaft brake 20. With
an increase of the size of the aperture 62, the plunger shaft 32
may therefore be disengaged from the aperture 62, and
correspondingly from the shaft brake 20, as discussed above. In
situations where the aperture 62 increases dramatically in size, as
mentioned previously, the second frictional force 44 may be
negligible or approximately zero. However, where the increase in
bridge width 66 is minimal, and results in a corresponding minimal
increase in the size of the aperture 62, the second frictional
force 44 may be at most less than either the first frictional force
42 or the vacuum force 40. It is contemplated that the bridge width
66 may increase due to deformation of the bridge 64 of the shaft
brake 20. This deformation may therefore allow the shaft brake 20
to disengage from the plunger shaft 32 and exert the second
frictional force 44 upon the plunger shaft 32. The deformation of
the bridge 64 may be permanent or elastic. In use, it is
contemplated that the deformation need only be permanent until the
needle 46 is fully retracted into the syringe cavity 28. Thus, the
shaft brake 20 may be fabricated from a material that experiences
prolonged plastic deformation. In addition, the ram member 22 may
at least partially sever the bridge 64 in order to increase the
bridge width 66. Thus, the bridge 64 may experience a permanent or
temporary change in its physical structure in order to provide an
increase in the bridge width 66 in response to engagement of the
ram member 22 with the shaft brake 20.
[0044] The shaft brake 20 may further include a release member 68
being disposed upon the shaft brake 20, as illustrated in FIGS. 1
and 2. The bridge width 66 may increase in response to engagement
of the ram member 22 with the release member 68. Although
illustratively shown in FIGS. 1 and 2, the release member 68 may be
configured in various ways, as dictated by design requirements. For
example, as mentioned above, the ram member 22 may be operative to
deform or to sever the bridge 64 of the shaft brake 20, which may
be done directly or indirectly. Thus, depending on the design, the
ram member 22 may engage the release member 68 and effectuate an
increase in the bridge width 66. As illustratively shown in FIGS. 1
and 2, the release member 68 may be a shoulder 70 protruding
upwardly from the shaft brake 20 opposite the syringe body 12, and
the ram member 22 may include a shoulder press 72 being sized and
configured to engage the shoulder 70 upon the piston 34 approaching
the bottom syringe body end 26, the bridge width 66 increasing in
response to the engagement of the shoulder press 72 with the
shoulder 70. The engagement of the shoulder press 72 with the
shoulder 70 may be done as illustrated in FIG. 2, with the shoulder
press 72 being oriented at an angle relative to the thumb platform
52, and the shoulder 70 being configured to substantially mate with
the shoulder press 72. Other various designs and configurations may
also be implemented.
[0045] The bridge width 66 may increase upon deformation of the
bridge 64 in response to engagement of the shoulder press 72 with
the shoulder 70 and continued movement of the piston 34 toward the
bottom syringe body end 26. Therefore, as discussed above, the
syringe may include a contact position whereat the user may know
that further displacement of the piston 34 toward the bottom
syringe body end 26 will result in engagement of the ram member 22
or shoulder press 72 with the shaft brake 20 or shoulder 70. Upon
further displacement then, the shaft brake 20 may exert the second
frictional force 44 upon the plunger shaft 32. This may be
accomplished by increasing the bridge width 66.
[0046] The shaft brake 20 may be configured to various embodiments
in order to increase the bridge width 66 in response to engagement
of the ram member 22 with the shaft brake 20. For example, the
brake body may define a body thickness 74 and the bridge 64 may
define a bridge thickness 76, as shown in FIG. 4. The bridge
thickness 76 may be less than the body thickness 74, and the bridge
64 may be operative to deform in response to the engagement of the
shoulder press 72 with the shoulder 70. Thus, upon engagement of
the ram member 22 with the shaft brake 20, the ram member 22 may be
configured to produce a deformation in the shaft brake 20. Thus, if
the ram member 22 produces a tensile force through the shaft brake
20, having the bridge thickness 76 less than the body thickness 74
may result in deformation along the bridge 64 and subsequent
increase in the bridge width 66, which then triggers exertion of
the second frictional force 44 upon the plunger shaft 32. In other
embodiments, the bridge thickness 76 may be less than the body
thickness 74 by allowing the bridge 64 to comprise a slit and a
laminated material extending across the slit. The laminate material
may have a lesser tensile strength than the shaft brake 20, and
therefore, as described previously, deform upon exertion of a
tensile force by the ram member 22 upon the shaft brake 20. This
deformation would likewise result in an increase in the bridge
width 66 and subsequent exertion of the second frictional force 44
upon the plunger shaft 32. Other embodiments and designs may be
employed to create desirable results.
[0047] As shown in an exemplary embodiment illustrated in FIG. 5,
in another implementation of the present invention, the bridge 64
may comprise a non-continuous slit 78 including a hinge element 80,
and the bridge width 66 increases upon deformation of the hinge
element 80 in response to engagement of the shoulder press 72 with
the shoulder 70 and continued movement of the piston 34 toward the
bottom syringe body end 26. Thus, instead of varying the bridge
thickness 76 relative to the body thickness 74, the bridge width 66
may simply vary relative to the brake body. In such an embodiment,
modifications such as this would result in deformation of the
bridge 64 and a resulting increase in the bridge width 66 upon
engagement of the ram member 22 and exertion of a tensile force
across the shaft brake 20.
[0048] The shaft brake 20 may be formed to include an anchor member
82 being disposed upon the shaft brake 20, as shown in FIGS. 1, 2
and 4. The anchor member 82 may be operative to mechanically couple
the shaft brake 20 to the attachment seal 14, as shown in FIGS. 1
and 2. However, it is contemplated that the anchor member 82 may
provide other various advantages for the shaft brake 20, other than
simple mechanical coupling to the attachment seal 14. For example,
it is contemplated that the anchor member 82 be operative to
provide at least a portion of the first and second frictional
forces 44 upon the plunger shaft 32. In such an embodiment, the
anchor member 82 may be configured as shown in FIGS. 1, 2 and 4.
Nevertheless, the anchor member 82 may be configured otherwise to
simply provide mechanical coupling to the attachment seal 14.
[0049] A method of mitigating retraction of a retractable needle
safety syringe 10, the syringe comprising a syringe body 12, an
attachment seal 14, a plunger assembly 16, a variable vacuum
compartment 18, a shaft brake 20, and a ram member 22, the syringe
body 12 defining opposing top and bottom syringe body ends 26 and
including a syringe cavity 28, the attachment seal 14 defining a
shaft orifice 30 and being attached to the top syringe body end 24,
the plunger assembly 16 including a plunger shaft 32 and a piston
34, the plunger shaft 32 defining opposing top and bottom shaft
ends 38, the plunger shaft 32 being disposed through the shaft
orifice 30 in the syringe cavity 28, the piston 34 being disposed
at the bottom shaft end 38, the plunger being slidably engaged with
the syringe body 12 within the syringe cavity 28, the variable
vacuum compartment 18 being disposed within the syringe cavity 28
between the piston 34 and the attachment seal 14, the variable
vacuum compartment 18 being operative to provide a vacuum force 40
on the plunger shaft 32 directed from the bottom syringe body end
26 toward the top syringe body end 24 with the vacuum force 40
increasing upon movement of the piston 34 toward the bottom syringe
body end 26, the shaft brake 20 being attached to the top syringe
body end 24 and being operative to frictionally engage the plunger
shaft 32 to provide first and second frictional forces 44 in
opposition to the vacuum force 40, the first frictional force 42
being exerted upon the plunger shaft 32 prior to the piston 34
reaching the bottom syringe body end 26, the ram member 22 being
attached to the top shaft end 36 and being formed to engage the
shaft brake 20 upon the piston 34 reaching the bottom syringe body
end 26, the shaft brake 20 exerting the second frictional force 44
upon the plunger shaft 32 in response to the engagement of the ram
member 22 with the shaft brake 20, the second frictional force 44
being less than the first frictional force 42. The method comprises
(a) exerting the first frictional force 42 upon the plunger shaft
32 in opposition to the vacuum force 40 prior to the piston 34
reaching the bottom syringe body end 26; (b) engaging the ram
member 22 with the shaft brake 20; and (c) exerting the second
frictional force 44 upon the plunger shaft 32 in opposition to the
vacuum force 40 in response to the engagement of the ram member 22
with the shaft brake 20. In an embodiment, with the syringe
including a needle 46, a further step in the method may include
automatically retracting the needle 46 to a position within the
syringe cavity 28.
[0050] In accordance with another aspect of the present method, the
shaft brake 20 may define a body perimeter 60 and include an
aperture 62 and a bridge 64, the aperture 62 being disposed within
the shaft brake 20 and being operative to frictionally engage the
plunger shaft 32, the bridge 64 defining the bridge width 66
extending radially from the aperture 62 toward the body perimeter
60, the shaft brake 20 being operative to exert the second
frictional force 44 upon the plunger shaft 32 in response to an
increase in bridge width 66, the bridge width 66 increasing in
response to the engagement of the ram member 22 with the shaft
brake 20, and step (b) of the method may further include:
increasing the bridge width 66 in response to engagement of the ram
member 22 with the shaft brake 20. Step (b) may also further
include: severing the bridge 64 in response to engagement of the
ram member 22 with the shaft brake 20. The severing may be done
with a sharp edge disposed upon the ram member 22. Alternatively,
the severing may be done utilizing a tool disposed on or
incorporated into the bridge 64 itself, with the ram member 22
merely providing actuating the tool's severing of the bridge 64. In
this regard, the bridge 64 may be variously configured to
facilitate the severance thereof. The properties of the material
used to fabricate the bridge 64 may also be manipulated as desired.
For example, the bridge 64 may be fabricated from a brittle
material that may sever or break upon engagement with the ram
member 22.
[0051] In accordance with another aspect of the present method, the
shaft brake 20 may further include a shoulder 70 being disposed
upon the shaft brake 20 and protruding upwardly from the shaft
brake 20 opposite the syringe body 12, the ram member 22 including
a shoulder press 72 being sized and configured to engage the
shoulder 70 upon the piston 34 approaching the bottom syringe body
end 26, the bridge width 66 increasing in response to the
engagement of the shoulder press 72 with the shoulder 70, and step
(b) of the method may further include: engaging the shoulder press
72 with the shoulder 70 and deforming the bridge 64 to increase the
bridge width 66. The engagement of the shoulder press 72 with the
shoulder 70 may be done as shown in FIG. 2, with the shoulder press
72 being oriented at an angle relative to the thumb platform 52,
and the shoulder 70 being configured to substantially mate with the
shoulder press 72. Other various designs and configurations may
also be implemented.
[0052] According to another implementation of the present method,
the syringe may further include a needle 46 being removably mounted
to the bottom syringe body end 26 and extending therefrom opposite
the top syringe body end 24, the piston 34 including a punch 48 to
engage the needle 6 upon the piston 34 reaching the bottom syringe
body end 26, the piston 34 being operative to remove the needle 46
into the syringe cavity 28 upon exertion of the vacuum force 40
upon the plunger shaft 32, and the method may further include the
steps of: engaging the needle 6 with the punch 48; and
automatically removing the needle 46 into the syringe cavity
28.
[0053] This description of the various embodiments of the present
invention is presented to illustrate the preferred embodiments of
the present invention, and other inventive concepts may be
otherwise variously embodied and employed. The appended claims are
intended to be construed to include such variations except insofar
as limited by the prior art.
* * * * *
References