Note: Descriptions are shown in the official language in which they were submitted.
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Title: Needle-Mounted Hypodermic Needle Guard
Field of the Invention
This invention relates to the safe disposal of
hypodermic needles by a guard device which protects the needle
tip from exposure after use. More particularly, it relates to
a mechanism for a tip protector which is storable on the
needle: and which automatically locks over the end of the
needle: when slid into position at the needle tip by the user.
Further, this invention concerns an improved needle guard
structure and assembly procedure by which the principal
components of a needle guard device may be mounted on a needle
laterally, from the side, rather than axially from the tip or
base end. The invention may also be adapted for use on a
catheter.
Background to the Invention
The type of needle guard to which this invention
relates has been described in Patent Cooperation Treaty
application No. PCT/CA90/00031 published on August 9, 1990
under international publication number WO 90/08564. This
prior PCT application describes a range of configurations for
needle guard devices which are stored at the base of a needle
and which automatically engage with and cover the tip of a
needle when moved to the tip.
All of the embodiments in the prior PCT application
contemplate installation of the needle guard device on the
needle through centrally located and axially aligned holes or
passages formed in the device. Such a configuration requires
that the devices be installed on the needle by passing the
needle centrally through the needle guard devices.
Where metal components are contained within the
needle guard device it is preferable to install the device on
a sharpened needle from the base end. This is because the
sharpened tip of a hypodermic needle must be maintained in a
pristine state, and no risk of blunting even a portion of the
tip should be allowed as part of the manufacturing process.
The assembly method of installing a needle guard
device on a needle from the base end requires that the needle
guard be introduced into the hypodermic needle assembly
process before assembly is complete. Following the
installation of the needle guard on the needle, the
manufacturing process customarily requires that the needle be
mounted, typically by epoxy glue or thermosetting plastic, in
the base.
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The necessity for mounting a needle guard device from
the base end of a needle would be less pressing if the needle
guard components exposed to the needle tip were of softer non-
metallic material, such as polymeric plastics. But even with
the exposure of the needle tip to only plastic materials, the
al9.gnment of a complicated mechanism having small axial
passages with a needle is complex and creates difficulties in
the assembly process.
In the PCT application described above, one of the
embodiments of the general invention disclosed therein, the
sixth embodiment, is of a configuration that, with
modification, may serve as a demonstration of a needle guard
that may be installed on a needle laterally, from the side.
Such a method of installation decreases significantly the
inconveniences described above.
In the prior art, U.S. patent No. 4,755,170 to Golden
shows a side-mounting cover for a needle tip. That cover
comprises a split-cork like device that includes no provision
for locking the cover in place when it is positioned over the
needle tip. No provision is made to prevent re-emergence of
the needle tip. And no provision is made to secure the cover
from removal, off the tip-end of a standard needle of constant
circumferential diameter.
The subject sixth embodiment of the prior PCT
application is a needle guard dtwice which is capable of
automatically engaging with the outer surface of a needle of
constant circumferential diameter and thereby prevent removal
of the device from the needle, once it is positioned over the
tip. It is also provided with means to prevent re-emergence
of the needle tip once the guard is in position, surrounding
the tip. This sixth embodiment relies on a "canted plate" to
engage and lock onto the needle when the needle guard is moved
to the needle tip. This "canted plate" device incorporates a
locking plate with a hole therethrough through which the
needle passes. This locking plate is canted to engage the
needle by the release of the needle-sensing portion of a lever
arm extension that is attached to the locking plate.
In the PCT application the expression "lever arm" is
used to describe both the lever arm extension and locking
plate, collectively, described in the earlier patent application
as forming a "U"-shaped element. For purposes of definition
hereafter, "lever arm" vaill be used to refer to the middle
portion and shorter leg of the "U" collectively; the middle
portion of the '°U" will be referred to as a "longitudinal
bar"; the shorter leg of the "U" will be referred to as the
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"sensing leg" of the lever arm, which leg may also serve as a
"blocking plate"; and the needle-contacting end on the blocking
plate will be referred to as the "sensing end" of the lever arm.
The invention herein in its general form, will next be
summarized, and then its implementation in the form of
specific embodiments will be detailed with reference to the
drawings following hereafter. These embodiments are intended
to demonstrate the principle of the invention, and the manner
of its implementation. As such they are merely exemplary.
The invention will then be further described, and defined, in
its most.general and more specific forms by means of the
series of claims which conclude this Specification. That
invention concerns an automatically locking, needle mounted
tip protecting needle guard device that permits such a needle
guard to be installed on a needle laterally, from the side,
and its adaptation to catheters. It also concerns a new
configuration for the lever arm that is of improved design.
Summary of the Invention
According to the invention, a needle guard is provided
that may be installed on a needle of constant circumferential
diameter for storage at the base of the needle and which
contains:
(1) engagement means for automatically engaging the outer
surface of the needle against further removal of the
needle guard from the needle when the needle guard is
moved to a position where it covers the needle tip: and
(2) means to prevent re-emergence of the needle tip from
the needle guard when the needle guard is maved to a
position where it covers the needle tip,
such needle guard further comprising:
(3) a body having an inner needle passageway throughout
the longitudinal length of such body and dimensioned to
permit a needle to be passed axially therethrough; and
(4) an opening provided along one side of the body, over
its entire longitudinal length, to provide a needle
access opening in the body which will permit a needle
shaft to laterally enter and be placed coaxially within
the inner needle passageway of said body.
In the specific exemplary embodiment described hereafter, the
needle guard comprises:
(1) a locking plate positioned within said cavity, the
locking plate having a needle opening pierced trans-
versely therethrough which is aligned with said
passageway so as to permit both to be pierced by a
needle when a needle is installed within the needle
guard body;
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(2) alignment means to maintain the locking plate and
transverse needle opening in a sliding alignment with
the needle while the needle tip is outside of the
needle guard; and
(3) canting means to cant the locking plate and needle
opening into locking engagement with the needle
when the tip enters within the needle guard;
the opening in the locking plate being exposed on one side
thereof to provide a locking plate needle access opening which
will permit a needle shaft to laterally enter and be placed
coaxially within the needle opening.
As an optional feature of the invention the needle
access opening in the body may be undercut to a width that will
allow the needle to be inserted laterally under pressure, but
will retain the needle within the inner needle passageway
thereafter.
As a further optional feature of the invention the
locking plate needle access opening may be narrowed in its
width to allow the needle to be inserted in the locking plate
needle opening under pressure, but retained therein thereafter.
As a further optional feature of the invention, the
aforesaid canting means includes a spring installed within a
spring cavity within the needle guard body, with a first end
of the spring being in contact with the body of the needle
guard, and the second end thereof being in contact with the
alignment means or locking plate so as to apply a canting
force to the locking plate, the spring cavity being outwardly
accessible through a spring cavity access opening. The spring
may be of a spirally-coiled compression type which applies its
canting force to the locking plate. Or the spring may be of a
torsional type that applies the canting force to the lever
arm. Optionally, the spring cavity access opening may open on
the same side of said body as the needle-access opening in the
body.
By a further optional feature of the invention, the
spring cavity access opening is undercut to a width that will
allow the spring to be inserted therein under pressure, but
will retain the spring within the spring cavity thereafter.
As a further optional feature of the invention, the
4o alignment means comprises a rotatable lever arm attached to
the locking plate, such lever arm having first and second
ends, the first end thereof being attached to the locking
plate and the second or needle-sensing end thereof being in
contact with and restrained by the shaft of a needle when a
needle is installed within the needle guard, the needle-
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sensing end of said lever arm comprising a recess which
partially embraces the surface of the needle against which it
rests.
As a further optional feature of the invention, the
lever arm comprises a laterally displaced longitudinal bar
which extends between its needle-sensing end which rests
against the needle and the locking plate, such longitudinal
bar being free to rotate with the locking plate in a plane and
being located in a position whereby the plane within which the
longitudinal bar rotates is laterally displaced from the
inner needle passageway within the body of the needle guard.
As a further optional feature of the invention, the
lever arm terminates at its second end with a blocking plate
portion which is biased by a spring to pass into the axial
path of the needle when the needle is drawn past the needle
sensing end of the lever arm, blocking re-emergence of the
needle. Additionally the blocking plate portion of the lever
arm may extend at one of its ends to the upper limit of the
needle guard body.
As a further feature of the invention a catheter
assembly comprising a catheter with a base and an insertion
needle passing therethrough is provided wherein the needle
guard is:
(1) frictionally coupled to and retained in association
with the base of the catheter, both during storage
and deployment of the needle guard, until the needle
guard is deployed to a tip-covering position whereupon
the needle guard engages with the needle;
(2) detachable from the base of the catheter upon further
removal of the catheter from the insertion needle; and
(3) mountable on the insertion needle from a lateral
position.
The foregoing summarizes the principal features of the
invention and its optional aspects. The invention may be
further understood by the description of the preferred
embodiments, in conjunction with the drawings, which now
follow.
Summary of the Figures
Figure 1 is a longitudinal cross-sectional view of a
canted plate locking device as depicted in the prior PCT
application showing the relationship of the parts in the
unlocked state.
Figure 1A shows an alternate form of lever arm to that
of Figure 1, also previously described in the PCT application.
Figure 2 is a longitudinal cross-sectional view of a
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canted plate locking device as depicted in the prior PCT
application showing the relationship of the parts in the locked
state.
Figure 3 is a partially disassembled top view of the
needle guard body, in this improved exemplary embodiment, with
components therein, mounted on a needle, and with the outer
sleeve coaxially displaced along said needle, prior to final
assembly
Figure 4 is a side view of the improved needle guard
with a series of three sectional end views taken along the side
view;
Figure 5 is a top view of a needle guard in which the
longitudinal portion of the lever arm is a lateral bar which
is oriented in a plane that is parallel to its plane of
rotation; and
Figure 6 i.s a side view of the needle guard of Figure
5, with two cross-sectional views taken from therein.
Figure 7 is a top view of a needle guard with a
different spring configuration.
Figure 8 is a front view, with cross-section, of the
embodiment of Figure 7.
Figure 9 is a depiction of the catheter assembly with
a side-mounting needle guard mounted thereon.
Description of the Preferred Embodiments
Tn Figure 1, the structure of one version of the
canted plate version of the needle guard 2 of the prior PCT
application is shown. In this Figure the general locking
means comprises a pivoting lever arm 101 of stiff material
attached to a locking plate 102 to ,form the general shape of a
broad "U" of unequal proportions. The longer portion of the
"U" is formed by the locking plate 102 which is provided with
a hole 1.03 of slightly larger diameter than that of the needle
shaft 1 sufficient to allow the locking plate 102 to "cant°' on
the needle 1 as shown in Figure 2. This shorter leg 109 of
the lever arm 109 is bent downwardly towards the needle 1.
As long as the leg 109 contacts the needle 1, it causes the
lever arm 101, of which it is a part, to serve as an
"alignment means" for aligning the locking plate 102 in
sliding alignment with the needle shaft 1.
A helical compression spring 104, also shown in
simplified cross-sectional view Figure 1, is contained in a
largely compressed state in longitudinal cavity 105 within the
guard body 106, with its free end 125 pressing against the
locking plate 102, and urging the lever arm 101 axially against
the sloping internal face 107 of body 106, making contact at
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pivot point 108. The turning moment of the spring force tends
to rotate lever arm 101 in a counter-clockwise direction about
pivot point 108, but the shorter vertical leg 109 of lever arm
101, referred to as the sensing leg 109, prevents rotation by
making contact with the needle shaft 1 at point 110.
Optionally the lever arm 101 may terminate directly in contact
with the needle 1 as a modified form of lever arm lOlB, as
shown in Figure 1A.
By appropriate choice of the slope of face 107 in
relation to the geometry of lever 101 and locking plate 102, a
component of reaction force will be developed to act at pivot
point 108 in a downward direction against locking plate 102,
equal and opposite to the upward reaction force against the
lever arm 101 at point 110. This balancing of vertical forces
against locking plate 102 substantially removes any radial
force between needle shaft 1 and the walls of hole 103 in
locking plate 102, thereby reducing axial frictional drag
between the needle and lever when moving the guard device
axially along the needle shaft. Alternately, the geometry may
be modified to create a degree of frictional resistance, if
this is desired.
In Figure 2 the needle shaft 1 is shown withdrawn into
the needle guard 2 and past the point of contact with the
needle-contacting or sensing end 110 of sensing leg 109 of
lever arm 101 and with the needle tip 4 within the needle
guard 2. This allows the lever arm 101 to rotate in a
counter-clockwise direction, as seen in Figure 2, about pivot
point 108 under the urging of spring 104, which rotates the
locking plate 102 until further rotation is prevented by the
axial misalignment of hole 103 and needle shaft 1. Thus the
spring 104, in conjunction with the body 106, serve as a
"canting means" to cant the locking plate 102.
By utilizing well-known relationships between the
thickness of the locking plate 102, the distance between the
pivot point 108 and the centre of the needle shaft 1, the
diameter of hole 103, the diameter of needle shaft 1, and the
coefficient of friction between locking plate 102 and needle
shaft 1, a critical geometry is established, whereby the axial
frictional grip between locking plate 102 and needle shaft 1
is always greater than an externally-applied axial force on
the needle directed to further remove the needle from the
guard, shown as direction "A" in Figure 2. Thus further
motion of the needle shaft 1 in this direction is prevented by
the locking of plate 102 on needle shaft 1, axial motion of
the locking plate 102 with respect to the guard body 106 being
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blocked by sloping face 107. With increasing applied axial
force in direction "A", this locking action will persist until
material deformation occurs, distorting the geometry beyond
the critical configuration.
This self-locking action is normally released if the
relative needle motion is reversed to direction "B", by
attempting to slide the guard device back onto the needle.
However, such motion is blocked by the presence of the sensing
leg 109 which serves as a blocking plate in the return path of
the needle, preventing re-exposure of the needle point by a
substantial obstruction of hardened material. Between these
two positions, the spring 104 will continue to maintain the
locking plate 102 at a canted angle.
Alternately or concurrently, a complementary pivot
point 136 may be provided on the guard body 106 adjacent to
and on the outward side of the spring 104 as shown in Figure
2. This pressure point 136 is located so as to apply a
canting force to a modified locking plate 132 through a
contacting flange 133 at the end of the locking plate 102 when
the needle is moved in the direction for re-emergence of the
tip, i.e., direction "B", thus providing a supplementary
locking of the guard, body 106 against removal in this
direction as well.
On initial displacement towards re-emergence, the
needle will carry the lever arm 101 forward to the position
lOlA whereat the contacting flange 133 rests against the
complementary pivot point 136, identified in this position as
133A. Any further attempt at displacement will apply the same
canting force to the modified locking plate 132. The guard
body 131 of Figure 1 is of a length sufficient to provide
clearance space for the additional displacement of lever arm
101. Additionally, the surface 134 on the interior body
portion 131 is inclined to provide freedom for the modified
locking plate 132 to remain canted.
To prevent the guard device from being removed forcibly
from the needle by its repeated rotation about the needle shaft,
the body 106 as shown in Figure 1 is preferably surrounded by
loosely-fitting sleeve 113, which provides rotational isolation
of the body 106 from the external operating means. Sleeve 113
is retained axially on body 106 by snap lips 114, fitting into
a circular rabbet 115 in one end of the body.
Referring to Figure l, the inner face 116 of sleeve
113 is optionally relieved over most of its surface to make
axial contact with body 106 only over a small diameter 117.
This reduces the frictional torque transmitted between sleeve
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113 and body 106 by combined axial and rotational force
applied to the guard device by the external operating means,
thus enhancing its rotational isolation.
The foregoing has constituted a description of the prior.
PCT device which has been adapted by the invention herein for
lateral installation on a needle.
In Figure 3, a modified needle guard 3 incorporating
features of the invention is shown in top view. The
background version of the needle guard used hereafter to
explain the invention relies on the canting plate to lock in
one direction only, but the double-locking version may be
utilized equally. Further, the embodiment being described is
intended to be merely exemplary of a side mounting needle
guard which automatically locks onto a needle when moved to
the tip.
In this new embodiment, a portion of the guard body
106 is absent on one side, forming an outer cavity 500, as
shown in Figure 3. This intersects with arid forms part of a
radially-disposed slot 501, shown in the three cross-sections
of Figure 4 and forming an outer needle access passage 501 in
the guard body 106. Slot 501 extends axially the full
longitudinal length of the guard body 106, cutting through the
two end portions 106A and central portion 106B of the body.
As best seen in cross-section C-C, the cylindrical inner
needle passageway 511 carries the needle, with a close,
sliding fit. The slot 501 penetrates to the inner needle
passageway 511 and the width of the intersection 512 which
forms the entrance to the needle passageway 511 is somewhat
less than the diameter of needle 1, so that the resulting
undercut allows a press-fit installation, but retains the
needle radially within its passageway 511.
Slot 501 extends radially beyond the needle cavity 511
to form a further penetration 522 into the guard body 106. By
thus reducing the remaining cross-section of the body 106, slot
extension 522 imparts additional compliance to the body 106,
allowing the needle 1 to be inserted laterally from the side by
springing open slot 501 sufficiently to allow the needle 1 to
pass the constriction at the undercut 512. As shown in cross-
section A-A of Figure 4, the needle 1 is positioned in slot
501 during assembly, and then pressed laterally into its
central position by an insertion bar 507, which extends the
full axial length of the body 106. The necessary springing-
open of slot 501 may be aided by widened flanks 513 on
insertion bar 507.
A spring access passage 502 is also provided. This is
best seen in cross-section C-C of Figure 4. This entrance to
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the spring cavity 105 may also be slightly under-cut at 503,
sufficiently wide to allow the spring 104 to be pressure-
fitted into the cavity 105, and narrowed enough to retain the
spring 104 within the cavity 105, once installed.
The spring cavity 105 is shown as having a spring
access passage 502 on the same side of the guard body 106 as
the needle access passage 501. However, these access passages
501, 502 need not necessarily be on the same side. The spring
cavity 105 may optionally be accessed from the reverse side or
even from the bottom.
The locking plate 102, attached to the lever arm 101,
is also provided with a needle access passage 504, shown in
cross-section A-A of Figure 4, that permits a needle 1 to be
inserted laterally into the locking plate needle opening 103
which forms a needle passageway through the locking plate 102.
The needle access passage 504 in locking plate 102 is
preferably located on the side of the lever arm 101 shown in
cross-section A-A of Figure 4, so that the needle 2 retains
the lever arm 101 laterally in its cavity in body 106.
Alternatively, the needle access passage 504 may be undercut
slightly, to provide retention of the lever arm lol on the
needle 1, in the same manner as the entrance 512 to needle
passageway 511 in body 106. By twisting the access passage
504 slightly during fabrication, and by correspondingly
twisting the needle 1 arid lever arm 101 relative to one
another during assembly, the needle 1 would be allowed to pass
this undercut, for installation in the locking plate needle
opening 103. This would allow needle access passage 504 to
be located on the opposite side of locking plate 102, thus
permitting the lever arm 101 and locking plate 102 to be
installed in guard 106 after installation of the needle 1 in
same.
The presence of the needle access passage 504 that
intersects the locking plate needle opening 103 must not
weaken the locking plate's ability to grasp and lock onto the
needle 1 when the locking plate 102 is canted. Using mild
carbon steel, it has been found that a locking plate of 0.50
mm thickness and 2.5 mm width is reasonably reliably capable
of maintaining structural integrity when pierced by a locking
hole of 0.9 mm diameter.
As a further optional feature, the sensing end 505 of
the shorter, sensing leg 109 of the lever arm 101 may be
indented as shown in cross--section B-B of Figure 4, to form a
slight notch or recess 506, which may be rounded so as to
partially embrace the needle 1. This recess 506 serves to
contribute to stability in locating the sensing end 505 on the
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needle 1. Such a recess 506 may also be formed in the needle-
contacting end of the configuration of needle arm 101A shown
in Figure 1A.
The locking plate end 509 of the locking plate 102 may
also optionally be provided with a small spur 510, as shown in
cross--section A-A of Figure 4, which interfits with the end of
the helical spring 104. This spur 510 further helps to locate
and stabilize the engagement of the spring 104 and the lever
arm 101.
The assembly procedure for this lateral or side-
mounting version of the needle guard may then be as follows:
1. The spring 104 is inserted laterally into its cavity 105,
by snapping it into place past its undercut 503 from the
side, as shown in cross-section C-C of Figure 4,
2. The spring 104 is then compressed by a thin depressor
finger (not shown) so that its right end is flush with
the open end of its cavity 105.
3. The lever 101 is inserted from the side, oriented in
approximately its locked position to clear the depressor
finger.
4. The depressor finger is removed, allowing the spring to
engage the spur 510 on the locking plate end 509 of the
lever arm 101.
5. A lever depressor (not shown) approaches from the right
to engage the locking plate 509 end of the lever 101 and
rotate it into its unlocked position as shown in Figure 4.
6. The outer sleeve 113 is placed over the needle 1 and
positioned towards the needle base, and the two are
positioned so that the needle is along-side and parallel
to the axis of the body 106, ready to enter the access
slot 501, as shown in cross-section A-A of Figure 4.
7. The needle 1 is moved into position from the side,
accompanied by sleeve 113, and is pressed into the
central needle passageway 511, by a suitable
insertion bar 507 extending the length of the needle
guard body 106. This is shown in cross-section A-A of
Figure 4. The bar 507 may have widened flanks 513 to
engage the tapered sides 514 of the access passage 501
and expand it sufficiently to allow easy needle entry.
8. The lever depressor is removed, and the entire inner
assembly may then be pressed into place within the outer
shell or sleeve 113.
As indicated by step six above, before assembly of the
guard body 106 onto the needle 101, the outer sleeve 113 may
be installed by sliding it axially aver the needle 1. Because
this part may be made of plastic and may have enlarged holes
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on its ends, this component may be more easily passed axially
over the needle 1 from either of its two ends. If passed over
the sharpened tip end, the enlarged holes will allow for less
critical mechanical assembly. As well, being made of plastic,
the sleeve 113 will not damage the sharpness of the tip of the
neE:dle 1.
As an alternate procedure the sleeve 113 may be formed
with a separation line that permits it to be elastically
expanded and to pass around the needle from a lateral position.
As a further alternate procedure the sleeve 113 may be made of
two parts that are fastened together after being placed around
the guard body.
The assembly procedure described was premised on a
version wherein the outer access passage 500, lever arm
access passage 504 and spring access passage 502 are all on
the same side. A correspondingly adjusted assembly procedure
would be followed where the location of any of these access
passages is reversed.
A principal advantage of the foregoing procedure, and
of the invention, is that it may be applied to needles for
hypodermic syringes or catheters, or needles and syringes,
after these components have been fully manufactured. Thus,
there need be no intervention in the already-existing
production process.
Referring now to Figure 1, for secure operation the
sensing leg 109, formed at the end of the lever arm 101, must
be large enough vertically to ensure that:
(1) in swinging into the path of the needle 1 to assume its
locked position, the sensing leg 109 will fully block the
needle path; and
(2) the further swinging of the lever arm 101 for a
significant distance beyond its locked position is not
obstructed by the lever arm coming into contact with the
needle 1 or the body 106.
This latter provision is necessary to accommodate variations
in the locked position of the lever arm, caused by
manufacturing tolerances and by deformations of the various
components of the needle guard.
In the prior art of Figure 1, the longitudinal bar 130
portion of the lever arm 101 is shown in a position wherein its
principal, centrally located plane of rotation passes through
the needle 1, and the needle passageway 511. As shown in
Figure 3 this longitudinal bar 130 is joined integrally at a
bend 524 to the sensing leg 109, which also serves as a needle-
blocking plate 109. In this configuration, the sensing leg 109
does not occupy the full vertical space of the interior cavity
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in the body 106, up to its outer cylindrical boundary 523.
In Figure 4, cross-section B-B, the greater the width
of the blocking plate 521 portion of the lever arm 101 is (to
provide security in blocking the needle 1), the more waste
space 526 occurs in the circular segment formed between the
upper surface 525 of the lever arm 101 and the outer
cylindrical boundary 523 of the body 106. Further waste space
is formed by the thickness 528 of the lever arm 101, as shown
in cross-section A-A of Figure 4.
To better utilize the interior space, and thus
increase the available lever arm swing for a given size of
needle guard body, it is advantageous to lengthen the blocking
plate 521, so that it extends to its full vertical limit, up
to the outer cylindrical boundary 523 of the guard body 106.
One means that might be considered for doing this
would be to add an extension flange that extends into the
waste space 526. However, this provides no advantage, as
lever arm 101 cannot swing far enough to utilize this
additional blocking plate area, because longitudinal bar 130
prevents the necessary additional rotation by striking the
needle 1 or central portion 106B of body 106.
An alternative embodiment is shown in Figures 5 and 6.
In this arrangement, the longitudinal bar 130 of the prior art
arrangement has been relocated by rotating it 90 degrees into
an orientation 130A. In this location the principal plane of
rotation of this relocated longitudinal bar 130A is laterally
displaced from the central needle passageway 511 formed in the
guard body 106. This is conveniently accomplished by
attaching the longitudinal bar (referred to sometimes
hereafter in such configuration as a "lateral bar" 130A) to
the edges of the locking plate 102A and blocking plate 521A.
These connections are preferably effected at positions that
are inward from the ends of such latter components.
Conveniently these connections may also be made at the ends of
the longitudinal bar 130A, but may also be attached inwardly
from such ends. By making the connections at the outermost
ends of the longitudinal bar 130A the locking plate 102A,
lateral bar 130A and blocking plate 521A may then be bent from
a single stamped sheet, and the blocking plate 521A may extend
fully to the limit of the cylindrical boundary 523 of the
guard body 106.
The lever arm lOlA of this configuration may thus be
described as having two components:
(1) a longitudinal bar 130A attached at one end to the
locking plate 102A~ and
14 - i4~.~eva~~~.
(2) a needle-sensing leg 109 which serves as a blocking
plate 521A, joined to the other end of the longitudinal
bar 130A.
Alternately, the needle-sensing leg 109 and blocking plate
521A may be separate elements, for instance, where the needle-
sensing leg 109 is formed inwardly of the blocking plate 521A.
The lateral bar configuration for the lever arm lOIA
can serve equally in a needle guard which is not characterized
by an inner needle passageway 511 which is open on one side of
the needle guard body 106. Thus, this lateral bar configuration
may be applied directly to the design of the sixth embodiment
described in PCT Application CA 9U/00031. The advantage of
use of a lateral bar 130A in the earlier design is the increased
flexibility provided for choosing the dimensions of the needle
guard.
In Figures 6 and 7 an alternate configuration for the
spring is depicted.
Instead of a compressional spring 104, Figures 6 and 7
depict use of a torsional spring 104A. The torsional spring
104A is mounted in a circular recess 540 within the body 106
of the needle guard. The helical axis of the torsional spring
104A is oriented in a direction which is parallel to the
direction of the plane of rotation of the laterally mounted
longitudinal bar 130A (in the sense that the direction of a~
plane is defined by the direction of a perpendicular thereto).
One end 542 of the torsional spring 104A is anchored in
a slot 543 within the needle guard body 106. The other end 544
is extended to provide a grasping arm 545 that is engaged with
the longitudinal bar 130A by means of a hooked-end 546 formed
at its free end. This hooked end 546, together with a suitable
spring geometry, enables the grasping arm 545 to bias the
longitudinal bar 104A to rotate in the manner described
previously.
A further alternate spring arrangement could employ a
leaf or bowed spring, set into a cavity in the body 106 above
the lever arm 101 from whence it may press downwards on to
the longitudinal bar 130. Where a lateral bar 130A is
employed, an extension from this linear spring would engage
the bar 130A.
These configurations have the disadvantage of
applying an off-centered, twisting force to the lever arm
101. The lever arm 101 may be stabilized by setting the
pivot point 108 of the locking plate 102 into a slight recess
547 formed in the face 107 of the body 106 against which the
locking plate 102 rotates. Alternately or concurrently, the
i~ ~ ~. ~,~ a ~.
- 15 -
grasping arm 545 of the torsional spring 104A may overlie the
longitudinal bar 130A or the hooked end 546 may be provided
with an extension 548 that overlies the longitudinal bar 130A.
In Figure 9 a catheter assembly o.f the intravenous
type is shown carrying a side-mounting needle guard 2 of the
type described herein as being exemplary of the principle of
the invention. The outer shell 113 of the guard 2 extends
over and is fractionally retained on the base portion 119 of
the: catheter 118 of the catheter assembly. The insertion
needle 1 extends through the guard 1 and catheter 118 to
emerge slightly beyond the distal end 120 of the catheter 118.
The inner diameter 121 of the extended portion of the
shell 113 is such as to provide a frictional coupling with the
guard 1 that will carry the guard 2 with the catheter 118 as
the insertion needle 1 is withdrawn from the catheter 118.
Upon reaching the point where the guard 2 encloses the tip 4,
the guard will engage automatically with the needle.
Thereafter further separation of the needle 1 and catheter 118
will cause the guard 2 to detach from the base portion 119 of
the catheter 118, leaving the guard 2 on the needle 1 in its
tip-protecting position.
Conclusion
The foregoing has constituted a description of
specific embodiments showing how the invention may be applied
and put into use. These embodiments are only exemplary.
Persons skilled in the art will be capable of adopting
modifications to the embodiments described which will serve
as equivalents, but still utilize the invention as set forth
herein. The invention in its broadest, and more specific
aspects, is further described and defined in the claims which
now follow.
