Patent Description:
A hypodermic needle fitted to a syringe is used for administering injections, such as to inject a medication or drug into a body. The injection is implemented by piercing skin tissue with the needle at a selected body region and then manually depressing a plunger attached to the needle, which forces out the injectant substance through the needle aperture. The needle may be reusable or disposable. For disposable or single use needles, the syringe (and/or the overall assembly encompassing the syringe and the needle) may include safety features to prevent needle reuse, in order to preclude contamination and to prevent potential injury from the exposed needle. Needle reuse can result in the transmission of infectious diseases, especially bloodborne viruses (BBVs), such as for example: the Human Immunodeficiency Virus (HIV) which leads to Acquired Immune Deficiency Syndrome (AIDS); the hepatitis B virus (HBV); and the hepatitis C virus (HCV). The needle/syringe safety features may include a needle guard or sheath to cover the needle when not in use, and a retraction mechanism to retract the needle inside a chamber after completion of the injection. The retraction may be implemented manually, requiring a special action by the user, or implemented automatically via a built-in mechanism configured to automatically retract the needle after use, such as a spring-based retraction mechanism. In a manual or "actively" implemented retractable syringe, the user must actively perform a particular step, such as manually pulling a sheath or needle guard to cover the potentially contaminated needle after use. An automatically implemented retraction may be "fully automated" or "passive", requiring no user action to activate the retraction mechanism. Alternatively, an automatically implemented retraction may be "partially automated" which still requires a certain action by the user. For example, the user may encounter a mechanical resistance when depressing the syringe plunger in a partially automated retractable syringe, such as due to the activation of the retraction mechanism, and must actively apply an additional force in order to activate the mechanism. An automated retraction mechanism may be configured to be activated only after the injection process has been completed. For example, there may be some type of retraction restraint which is only released when the injection is fully executed.

Many conventional syringes include some form of indication to the user (e.g., a medical clinician administering the injection with the syringe) to signify that the injection has been successfully executed. For example, the syringe may provide a visual and/or audible indication, such as via a designated sound such as a "click", to signify completion of the injection. In syringes configured with automated retraction mechanisms, the designated indication may be provided by the mechanism and may also signify the release of the retraction mechanism restraint. Accordingly, when the user depresses the syringe plunger and hears the designated indication sound, he/she is aware that the substance has been fully injected from the needle, and also that the retraction restraint has been released to enable subsequent activation of the needle retraction. However, a user (especially an inexperienced user) may not always fully depress the plunger as a result of the additional resistance (i.e., in addition to the substance injection resistance) caused by the retraction mechanism activation, making it difficult to push the plunger fully all the way. The user may incorrectly perceive the resistance as signifying that the injection was carried out, even though the plunger was not actually fully depressed and no indication was provided. In such a case, the injectant substance may not be expelled fully (or even partially) into the body, and the retraction restraint would not be released thereby preventing the subsequent activation of the automated needle retraction, leading to possible contamination and needlestick injury from the still extended and used needle.

Various safety needle assembly configurations are known in the art. Some examples include: <CIT> to Mitchell, entitled: "Syringe guard system for a unit dose syringe"; <CIT> to Doyle, entitled: "Passive needle guard for syringes"; <CIT> to Westbye, entitled: "Syringe with anti-rotation for luer lock"; <CIT>, entitled: "Automatic needle device"; <CIT>, entitled: "Anti-needle stick safety device or system for use with drugs requiring reconstitution"; <CIT>, entitled: "Automatic injection device"; <CIT>, entitled: "Patient-contact activated needle stick safety device"; <CIT>, entitled: "System and method for an injection using a syringe needle"; <CIT>, entitled: "Safety needle assembly"; and <CIT>, entitled: "Automatic needle apparatus".

The present invention overcomes the disadvantages of the prior art by providing an automatically retracting safety needle assembly that activates a safety retraction mechanism after completion of the injection, while minimizing the likelihood of the user inadvertently terminating the syringe plunger depression before the injection has fully completed, and without requiring the application of additional force by the user (i.e., in addition to the basic injection force) in order to activate the safety mechanism. When the user depresses the syringe plunger to perform the injection, the safety needle assembly does not exert an additional opposing resistance force with an abrupt resistance increase for activation of the safety mechanism, as common in conventional springloaded safety syringes. Rather, the user encounters a relatively constant resistance force throughout the advancement of the syringe plunger along the syringe chamber that compels a continuous depressing of the syringe plunger, thus enabling full completion of the injection process with high reliability and avoiding its premature termination, and substantially ensuring the activation of the safety mechanism. The completion of the injection, as signified by at least one visual/audible/tactile indicator on the safety needle assembly, provides for full expulsion of the injectant substance via the syringe needle and enables the release of the retraction mechanism restraints. This is followed by the automated syringe retraction, allowing for safe discarding of the needle to prevent potential hazards by a contaminated exposed needle, such as needlestick injury.

Reference is now made to <FIG>, which collectively illustrate a safety needle assembly, generally referenced <NUM>, according to a first embodiment of the present invention. Assembly <NUM> includes an external housing (EH) <NUM>, an internal housing (IH) <NUM>, a rotating sleeve (ROS) <NUM>, a biasing element (BE) <NUM>, an activation fork (AF) <NUM>, and a syringe <NUM>. Assembly <NUM> has a distal end and a proximal end, which is depicted in <FIG> in the context of external housing <NUM>, where the distal end faces away from the user holding assembly <NUM> and towards the injection site. Assembly <NUM> is also defined by a longitudinal axis, extending lengthwise along the assembly between the proximal and distal ends, where an "axial" direction corresponds to a direction parallel to the longitudinal axis (i.e., towards or away from the proximal or distal ends), whereas a "radial" direction corresponds to a direction orthogonal to the longitudinal axis, and extending radially therefrom.

<FIG> is an illustration of external housing <NUM> of safety needle assembly <NUM>, including a perspective view, orthogonal side views, and a sectional view thereof. External housing <NUM> is primarily cylindrical or tubular shaped and encases the other components of assembly <NUM>. External housing <NUM> includes at least one grip <NUM>, disposed at a proximal portion on the exterior surface of external housing <NUM>, by which the user can hold onto or grip assembly <NUM>. External housing <NUM> further includes a pair of transparent windows <NUM>, arranged lengthwise on the exterior surface of external housing <NUM> between grip <NUM> and the distal end of external housing <NUM>. Windows <NUM> are configured to provide a view of the injectant substance prior to and during the injection process, such that the user can observe relevant characteristics relating to the substance, such as the substance quality, as well as if and how much of the substance is actually being injected. While two windows <NUM> are depicted for exemplary purposes, external housing <NUM> may generally include any number of windows, and may be characterized by any suitable size or shape. External housing <NUM> further includes a flange <NUM>, consisting of opposing ledges or protrusions projecting radially outward at the proximal end of external housing <NUM>, such that the user can press his fingers against flange <NUM> to provide a counterforce when depressing the syringe plunger (e.g., by applying a clamping force with his fingers between flange <NUM> and the syringe plunger rod <NUM> of syringe <NUM> as described hereinbelow). An opening <NUM> at the distal end of external housing <NUM> allows the syringe needle to extend through opening <NUM> during the injection process. A plurality of small apertures <NUM> are symmetrically arranged on opposing sides of external housing <NUM> at the proximal end of grip <NUM> distally of flange <NUM>, with two apertures positioned adjacently on each side. It is appreciated that external housing <NUM> may be considered optional and assembly <NUM> may alternatively be configured without external housing <NUM>, for example, where associated external housing components, such as grip <NUM> and flange <NUM>, may alternatively be disposed directly on internal housing <NUM>.

<FIG> is an illustration of internal housing (IH) <NUM> of safety needle assembly <NUM>, including a perspective view, side and top views, and a sectional view thereof. Internal housing <NUM> includes an inner tube <NUM> concentrically disposed within an outer tube <NUM>, where inner tube <NUM> is affixed to outer tube <NUM> via a pair of radially extending connecting ribs <NUM>. A base wall <NUM> is positioned within inner tube <NUM>. A pair of directing protrusions <NUM> project outwards radially from the outer wall of inner tube <NUM>. Guiding ribs <NUM> are situated on opposite sides on the inner part of outer tube <NUM>. Internal housing <NUM> includes two pairs of short connecting protrusions <NUM>, each pair extending radially outwards at the proximal end of outer tube <NUM> at a respective side thereof. Internal housing <NUM> further includes a pair of short orienting protrusions <NUM> extending axially and located at the proximal end of inner tube <NUM>. Internal housing <NUM> further includes a pair of locking snaps <NUM>, which are larger elongated projections extending axially from opposite sides at the distal end of internal housing <NUM>. Each locking snap <NUM> is characterized by a substantially straight proximal surface <NUM>. Locking snap <NUM> includes a triangular-shaped ridge <NUM> protruding radially outwards from the outer surface of locking snap <NUM> and generally facing distally.

It should be noted that the "external housing" and the "internal housing" can be considered two parts of a single component which can be collectively referred to as a "housing". Accordingly, external housing <NUM> and internal housing <NUM> are represented herein as two separated pieces or components for convenience of manufacturing considerations, but can alternatively can be manufactured as a single integral component using different manufacturing technologies.

<FIG> is an illustration of rotating sleeve (ROS) <NUM> of safety needle assembly <NUM>, including a perspective view, side and top views, and a sectional view thereof. ROS <NUM> is generally cylindrical or tubular shaped with a hollow core, and includes a pair of extending arms <NUM> extending distally from a flange wall <NUM> at the proximal end of ROS <NUM>. The inner diameter and axial length of ROS <NUM> are larger than that of inner tube <NUM> of internal housing <NUM>. Each extending arm <NUM> has an opening or guiding slot <NUM> consisting of different slot sections: a short helical-shaped slot portion <NUM> at the proximal edge; an elongated straight slot portion <NUM> distal of helical-shaped slot portion <NUM>; and a semi-hexagonal shaped extension slot portion <NUM> extending from the middle of straight slot portion <NUM>. Flange wall <NUM> has a pair of arc-shaped openings <NUM> symmetrically arranged on opposite sides. Flange wall <NUM> is further characterized by notched flanges <NUM> protruding radially outwards on opposite sides, adjacent to openings <NUM>. Each notched flange <NUM> is characterized by a wide notch <NUM>. A pair of teeth <NUM> projects radially outwards from the perimeter of flange wall <NUM> in between notched flanges <NUM>. ROS <NUM> further includes a pair of holding snaps <NUM>, which are short protrusions projecting proximally from the edges of flange wall <NUM>, arranged orthogonal to wide notches <NUM>. It is noted that certain components of ROS <NUM> are described herein for exemplary purposes as being of a plurality, such as: two extending arms <NUM>; two arc-shaped openings <NUM>; two notched flanges <NUM>; two holding snaps <NUM>; and two teeth <NUM>. However, ROS <NUM> may more generally be configured with any number of these respective components, such as for example, by including only one extending arm <NUM>; one arc-shaped opening; one notched flange <NUM>; one holding snap <NUM>; and/or one tooth <NUM>, in an alternative embodiment. In a further alternative embodiment, ROS <NUM> may be configured with an outer diameter that is smaller than the inner diameter of inner tube <NUM> of IH <NUM>. Correspondingly, the pair of directing protrusions <NUM> of IH <NUM> may project radially inwards from the inner wall of inner tube <NUM> (i.e., rather than projecting radially outwards), and the triangular-shaped ridge <NUM> of locking snap <NUM> of IH <NUM> may protrude radially inwards from the outer surface of locking snap <NUM> (rather than protruding radially outwards) and generally face distally.

Biasing element <NUM> may be embodied, for example, by a compression spring, or more generally by any suitable device or mechanism configured to apply an axial biasing force against ROS <NUM> and IH <NUM>.

<FIG> is an illustration of activation fork (AF) <NUM> of safety needle assembly <NUM>, including a perspective view, a side view, a sectional view, and a detailed view thereof. AF <NUM> is generally cylindrical or tubular shaped with a hollow core and includes a pair of arc-shaped guiding arms <NUM> extending distally from an end member <NUM> at the proximal end of AF <NUM>. End member <NUM> is generally circular and "ring" shaped, i.e., with a hollow central portion, but may alternatively be a different shape or form, such as a filled (non-hollow) plate. End member <NUM> has a slightly larger radius than that of guiding arms <NUM> (along the radial axis). Each guiding arm <NUM> has a groove <NUM> extending longitudinally along the inner surface thereof, where the groove <NUM> terminates at a shoulder <NUM> at the distal end of guiding arm <NUM>. It is noted that AF <NUM> may alternatively be configured with only a single guiding arm <NUM>, or more generally may be configured with any number of guiding arms <NUM>, but is described herein for exemplary purposes as including two guiding arms <NUM>.

<FIG> is an illustration of syringe <NUM> of safety needle assembly <NUM>, including a perspective view, a side view, and a sectional view thereof. Syringe <NUM> includes a cylindrical syringe chamber <NUM>, which is bordered at its proximal end by a syringe flange <NUM>. Syringe <NUM> further includes a needle <NUM> which extends from the distal end of syringe <NUM>, distally from syringe chamber <NUM>. Syringe <NUM> further includes a syringe plunger rod <NUM> bordered at its proximal end by a finger rest <NUM>, which is typically a disc with its surface orthogonal to the longitudinal axis. A plunger stopper <NUM> is disposed at the distal end of plunger rod <NUM>. Plunger rod <NUM> is slidable advanceable within syringe chamber <NUM>, such that when plunger rod <NUM> is pressed forward (in a distal direction) in syringe chamber <NUM>, such as due to the application of force against finger rest <NUM>, an injectant substance contained within syringe chamber <NUM> is propelled distally by plunger stopper <NUM> through needle <NUM>.

<FIG> provide different views of safety needle assembly <NUM> in a "storage state" or a "non-deployment state", representing the configuration of assembly <NUM> when not in use (i.e., before implementing an injection). Internal housing <NUM> is concentrically arranged within external housing <NUM> and is fixedly coupled to external housing <NUM> by connecting protrusions <NUM> of internal housing <NUM> engaging with apertures <NUM> at the proximal end of external housing <NUM>. In the event that external housing <NUM> and internal housing <NUM> are formed as a single integrated component, then protrusions <NUM> of internal housing <NUM> and apertures <NUM> of external housing <NUM> can be eliminated and outer tube <NUM> of internal housing <NUM> can be formed as part of external housing <NUM>. ROS <NUM> is also concentrically arranged within external housing <NUM>. In particular, ROS <NUM> is disposed between outer tube <NUM> and inner tube <NUM> of internal housing <NUM>, where extending arms <NUM> extend through the distal end of internal housing <NUM> and directing protrusions <NUM> on the outer wall of inner tube <NUM> are positioned within helical-shaped slot portion <NUM> of guiding slots <NUM> of respective extending arms <NUM>. Locking snaps <NUM> of internal housing <NUM> are positioned within slot extensions <NUM> of guiding slots <NUM> of respective extending arms <NUM>. Orienting protrusions <NUM> at the proximal end of inner tube <NUM> are positioned through arc-shaped openings <NUM> of flange wall <NUM> of ROS <NUM>.

BE <NUM> is disposed within inner tube <NUM>, and supported at its distal end by base wall <NUM> of internal housing <NUM> and supported at its proximal end by flange wall <NUM> of ROS <NUM>. Guiding arms <NUM> of AF <NUM> are positioned between ROS <NUM> and outer tube <NUM> of IH <NUM>. In particular, end member <NUM> at the proximal end of AF <NUM> is coupled to finger rest <NUM> of syringe plunger rod <NUM>, while guiding arms <NUM> of AF <NUM> are guided by guiding ribs <NUM> on the inner part of outer tube <NUM>. Guiding arms <NUM> are also positioned inside wide notch <NUM> of notched flange <NUM> at proximal end of ROS <NUM>, and teeth <NUM> of notched flange <NUM> are inserted in groove <NUM> on the inner surface of guiding arms <NUM>. Syringe <NUM> is positioned within inner tube <NUM> of IH <NUM> and coupled to ROS <NUM> by holding snaps <NUM>.

BE <NUM> applies an axial force (e.g., a spring force) that biases ROS <NUM> to the proximal direction. ROS <NUM> is rotatable and axially movable but is prevented from rotation and axial movement when in storage position by AF <NUM> (i.e., due to the positioning of guiding arms <NUM> within wide notch <NUM> of notched flange <NUM>). Syringe <NUM> is rotatable and axially movable but is prevented from such when in storage position, as holding snaps <NUM> and flange wall <NUM> prevent axial motion of syringe flange <NUM> relative to ROS <NUM>, while orienting protrusions <NUM> prevent rotation of syringe flange <NUM>. AF <NUM> is limited from further proximal motion by teeth <NUM> of ROS <NUM> engaging with shoulder <NUM> of guiding arm <NUM>, preventing the removal of AF <NUM> from assembly <NUM>.

When assembly <NUM> is in a storage state, syringe needle <NUM> extends at least partially through distal opening <NUM> and is encased by a needle guard <NUM>. Needle guard <NUM> is a short thin tube which is opened at its proximal end and closed at its distal end. The proximal edge of needle guard <NUM> is partially embedded within opening <NUM>. Needle guard <NUM> is tightly wrapped around the base of needle <NUM>. Needle guard <NUM> serves to prevent contamination or needlestick injury from an exposed needle <NUM>, and acts as a barrier for the injectant substance when assembly <NUM> is in a storage state.

To deploy assembly <NUM> for performing an injection, a user (e.g., a medical clinician) holds assembly <NUM>, preferably via grip <NUM>, and removes needle guard <NUM>, such as by pulling needle guard <NUM> in the distal direction, to expose needle <NUM>. The user inserts the exposed distal end of needle <NUM> into an injection site (e.g., a body region of a patient to be injected). <FIG> is a side view illustration of safety needle assembly <NUM> during a needle insertion stage. After needle <NUM> has been inserted into the injection site, the user presses syringe finger rest <NUM> which pushes plunger rod <NUM> in the distal direction together with AF <NUM>. The distal advancement of plunger rod <NUM> mutually advances plunger stopper <NUM> within syringe chamber <NUM>, which propels the injectant substance distally within chamber <NUM> to pass through the distal aperture of needle <NUM> and enter the injection site. The progress of plunger rod <NUM> and plunger stopper <NUM> along chamber <NUM> and the passage of the injectant substance can be viewed through windows <NUM>. <FIG> is an illustration of safety needle assembly <NUM> during an injection stage, including orthogonal side views and a sectional view.

The distal advancement of syringe plunger rod <NUM> continues until guiding arms <NUM> of AF <NUM> pass through wide notches <NUM> of notched flange <NUM> of ROS <NUM>, allowing for rotation of ROS <NUM> inside end member <NUM> of AF <NUM>. Syringe <NUM> and ROS <NUM> are held in place by the force applied by the user pressing (distally) against finger rest <NUM> at the end of syringe plunger rod <NUM>. <FIG> is a side view illustration of safety needle assembly <NUM> during the end of an injection stage, including orthogonal side views and a sectional view, showing the respective alignments of ROS <NUM>, AF <NUM> and syringe <NUM> at this stage.

Safety needle assembly <NUM> provides a smooth and substantially constant opposing resistive force during the advancement of syringe plunger rod <NUM>, without an abrupt force increase needed to activate the safety retraction mechanism as in conventional (partially automated) safety syringes. The smooth and substantially constant resistance compels the user to fully depress syringe plunger rod <NUM> (by continuing to press against finger rest <NUM>) without prematurely terminating the distal advancement of plunger rod <NUM> along syringe chamber <NUM> before the injection process has been fully carried out and the safety mechanism has been activated. Reference is now made to <FIG>, <FIG> and <FIG>. <FIG> is a graph, generally referenced <NUM>, of resistive force exerted against the user depressing the syringe plunger rod, as a function of the plunger rod displacement, of a standard safety needle assembly having an automatic retraction mechanism known in the art. <FIG> is a graph, generally referenced <NUM>, of resistive force exerted against the user depressing the syringe plunger rod, as a function of the plunger rod displacement, of a safety needle assembly operative in accordance with an embodiment of the present invention. The x-axis of graphs <NUM>, <NUM> represents the displacement or advancement of the syringe plunger along the syringe chamber (denoted as "machine extension") in millimeters (mm), while the y-axis represents the opposing or resistive force exhibited by the syringe (denoted as "load"), in Newtons (N). Graph <NUM> is characterized by an initial flat portion (referenced <NUM>) representing an initial constant resistive force exhibited by the syringe of a standard safety needle assembly during the initial stages of the injection. After the syringe plunger has advanced beyond a certain point, there is an abrupt spike in resistive force, shown by curve portion <NUM> at approximately <NUM>. To overcome this resistive spike, the user must apply an increased counterforce to keep depressing the plunger and maintain its advancement in order to complete the injection process and to activate the retraction mechanism. As the syringe plunger advances further, the resistive force exhibits rapid conjoining peaks at curve portion <NUM> (at approximately <NUM>-<NUM>), signifying that the retraction restraint has been effectively released so as to trigger the activation of the retraction mechanism (where the pair of peaks represent the successive release of corresponding snaps which previously restrained the retraction mechanism in this example). The retraction mechanism activation is generally accompanied by an audible indication, such as a click sound, to signify the activation. A biasing force from the compression spring (or other biasing element) is subsequently applied against the activated retraction mechanism, producing an indefinite resistive force increase at curve portion <NUM>. Thus, as seen in graph <NUM>, a substantial user applied counterforce, of approximately 4N, is required in order to overcome the resistive force needed to ensure full advancement of the syringe plunger and completion of the injection to activate the retraction mechanism in a standard partially automated retractable needle assembly.

In contrast, no such substantial user counterforce is needed for assembly <NUM>. Graph <NUM> is also characterized by an initial flat portion <NUM> representing an initial constant resistive force during the initial injection phase. However, this constant resistive force continues throughout the advancement of the syringe plunger until the retraction mechanism is activated (due to the process elaborated upon further hereinbelow) at approximately <NUM> advancement. This is followed by a brief drop in resistive force (at curve portion <NUM>), as the remainder of the injectant substance is expelled from the syringe needle, followed by an indefinite increase (at curve portion <NUM>) due to the biasing force applied by biasing element <NUM>. Accordingly, the relative constant resistance encountered in assembly <NUM> compels the user to continue to fully depress syringe plunger rod <NUM> (by pressing distally against finger rest <NUM>), without prematurely terminating the distal advancement along syringe chamber <NUM> before the injection process has been fully carried out and the safety mechanism has been activated. A visual comparison of graphs <NUM> and <NUM> can be seen in <FIG>.

After the injection process is completed, the user releases the distal force applied to syringe plunger rod <NUM> by stopping to press finger rest <NUM>, which reduces the axial force applied to syringe <NUM> and ROS <NUM>. This allows the biasing force of BE <NUM> to move ROS <NUM> axially toward the proximal direction, resulting in directing protrusions <NUM> of IH <NUM> (initially positioned within helical-shaped slot portion <NUM> of guiding slots <NUM>) urging rotation of ROS <NUM>. Orienting protrusions <NUM> of IH <NUM> prevent rotation of syringe <NUM> by engaging syringe flange <NUM>, thus limiting syringe <NUM> to axial motion. The rotation of ROS <NUM> causes locking snaps <NUM> to be repositioned out of slot extensions <NUM> and into elongated straight slot portion <NUM> of guiding slot <NUM>. The rotation of ROS <NUM> also causes directing protrusions <NUM> to be repositioned out of helical-shaped slot portion <NUM> and into elongated straight slot portion <NUM> of guiding slot <NUM>. This in turn allows for further axial movement of ROS <NUM> in the proximal direction. The proximal motion of ROS <NUM> causes ridge <NUM> on the outer surface of locking snap <NUM> to engage the distal end of guiding slots <NUM> and bend radially inwards to allow further proximal advancement of ROS <NUM>. The proximal axial movement of ROS <NUM> is accompanied by the mutual proximal axial movement of syringe <NUM>, which in turn causes syringe needle <NUM> to retract into the assembly housing (external housing <NUM> and/or internal housing <NUM>). When the distal end of guiding slots <NUM> engages directing protrusions <NUM>, the proximal motion of ROS <NUM> is restricted, while the distal end of extending arms <NUM> fully passes locking snaps <NUM>, enabling locking snaps <NUM> to deflect radially outwards and return to a relaxed (unbent) position where proximal surface <NUM> of locking snaps <NUM> restricts distal movement of ROS <NUM> and syringe <NUM>. <FIG> is an illustration of safety needle assembly <NUM> during a first portion of a syringe retraction stage, including a side view, a sectional view, and a detailed view thereof, where external housing <NUM> and AF <NUM> are concealed, providing a view of the internal components of assembly <NUM> at this stage. <FIG> is an illustration of safety needle assembly <NUM> during a second portion of a syringe retraction stage, including a side view, a sectional view, and a detailed view thereof, where external housing <NUM> and AF <NUM> are concealed, providing a view of the internal components of assembly <NUM> at this stage.

After syringe <NUM> has been fully retracted such that needle <NUM> is completely positioned within EH <NUM> and/or IH <NUM>, the distal end of extending arms <NUM> of ROS <NUM> are positioned between respective directing protrusions <NUM> and locking snaps <NUM> of IH <NUM>. This places assembly <NUM> in a "safe discard state", as directing protrusions <NUM> prevents further proximal motion of ROS <NUM> and syringe <NUM>, while locking snaps <NUM> prevents distal motion of ROS <NUM> and syringe <NUM>. Furthermore, AF <NUM> is restricted from being distally pulled out of assembly <NUM> due to the alignment of AF guiding arms <NUM> relative to ROS <NUM> as the proximal end of AF guiding arms <NUM> has a smaller radius than that of notched flange <NUM>. The user may then safely dispose of needle <NUM> and assembly <NUM> when in the safe discard state. <FIG> is an illustration of safety needle assembly <NUM> in a discard state, including side views, a sectional view, and a detailed view thereof, where external housing <NUM> and AF <NUM> are concealed, providing a view of the internal components of assembly <NUM> at this stage.

Safety needle assembly <NUM> may further include an indicator (not shown), configured to denote the progress of the injection process, and to signify that the injectant substance has been fully injected, such as by a visual indication, an audible indication and/or a tactile indication. For example, the indicator may be embodied by windows <NUM> of EH <NUM>, which provides visibility of the progress of plunger stopper <NUM> during the injection. The indicator may further facilitate the user to continue to depress syringe plunger rod <NUM> all the way without prematurely terminating the applied force before the injection process has been fully carried out. For another example, the indicator may be a "click" sound that is audible by the user at the end of the injection process when ROS <NUM> disengages from guiding arms <NUM> of AF <NUM>. The release of ROS <NUM> may also provide a tactile indication to the user, due to the corresponding release of BE <NUM> applying a proximal force through syringe <NUM> to the user pressing finger rest <NUM>.

Reference is now made to <FIG>, which collectively illustrate a safety needle assembly, generally referenced <NUM>, according to a second embodiment of the present invention. Assembly <NUM> includes an external housing (EH) <NUM>, an internal housing (IH) <NUM>, a locking sleeve (LOS) <NUM>, a biasing element (BE) <NUM>, an activation fork (AF) <NUM>, and a syringe <NUM>. Assembly <NUM> has a distal end and a proximal end, which is depicted in <FIG> in the context of external housing <NUM>, where the distal end faces away from the user holding assembly <NUM> and towards the injection site. Assembly <NUM> is also defined by a longitudinal axis, extending lengthwise along the assembly between the proximal and distal ends, where an "axial" direction corresponds to a direction parallel to the longitudinal axis (i.e., towards or away from the proximal or distal ends), whereas a "radial" direction corresponds to a direction orthogonal to the longitudinal axis, and extending radially therefrom.

External housing <NUM> of assembly <NUM> (illustrated in <FIG>) is identical to external housing <NUM> of assembly <NUM> (illustrated in <FIG>).

Internal housing <NUM> of assembly <NUM> (illustrated in <FIG>) includes an inner tube <NUM> concentrically disposed within an outer tube <NUM>, where inner tube <NUM> is affixed to outer tube <NUM> via a plurality of (e.g., four) radially extending connecting ribs <NUM>. A base wall <NUM> is positioned within inner tube <NUM>. Guiding ribs <NUM> are situated on opposite sides on the inner part of outer tube <NUM>. IH <NUM> includes two pairs of short connecting protrusions <NUM>, each pair extending radially outwards at the proximal end of outer tube <NUM> at a respective side thereof. IH <NUM> further includes a pair of stopping protrusions <NUM> extending radially inwards from the inner surface of outer tube <NUM> at the proximal end thereof. Inner tube <NUM> includes gripping slopes <NUM> on opposite sides thereof. Each gripping slope <NUM> is characterized by an outwardly sloping surface near the distal end of inner tube <NUM>. Gripping slopes <NUM> are situated perpendicular to stopping protrusions <NUM>.

Locking sleeve (LOS) <NUM> of assembly <NUM> (illustrated in <FIG>) is a cylindrical tube with a hollow core and includes a pair of extending arms <NUM> extending distally from a flange wall <NUM> at the proximal end of LOS <NUM>. The inner diameter and axial length of LOS <NUM> are larger than inner tube <NUM> of internal housing <NUM>. LOS <NUM> further includes a pair of stopping protrusions <NUM> extending distally from flange wall <NUM> on opposite sides in between (and orthogonal to) extending arms <NUM>. Stopping protrusion <NUM> is characterized by a narrow flat-edged flap extending distally from a wider base portion adjacent to flange wall <NUM>, where the length of stopping protrusion <NUM> is slightly shorter than that of extending arm <NUM>. Each extending arm <NUM> includes a gripping snap <NUM> at the proximal end of LOS <NUM>. Gripping snap <NUM> has a radially inward facing slope <NUM> at the distal end thereof. Each extending arm <NUM> further includes a locking snap <NUM> positioned adjacent to and distally from the respective gripping snap <NUM>. Locking snap <NUM> has a deflecting slope <NUM> at the distal end thereof, the deflecting slope <NUM> facing proximally and radially inwards. LOS <NUM> includes arcuate ridges <NUM> extending proximally from the edges of flange wall <NUM>, proximate to gripping snaps <NUM> of extending arms <NUM>. LOS <NUM> further includes a pair of holding snaps <NUM>, which are short protrusions projecting proximally from the edges of flange wall <NUM> in between (and orthogonally to) ridges <NUM>. It is noted that certain components of LOS <NUM> are described herein for exemplary purposes as being of a plurality, such as: two extending arms <NUM>; two stopping protrusions <NUM>; two gripping snaps <NUM> (i.e., one on each extending arm <NUM>); two locking snaps <NUM> (i.e., one on each extending arm <NUM>); and two holding snaps <NUM>. However, LOS <NUM> may more generally be configured with any number of these respective components, such as for example, by including only one extending arm <NUM> (with a respective gripping snap <NUM> and respective locking snap <NUM>); one stopping protrusions <NUM>; and one holding snap <NUM>, in an alternative embodiment. In a further alternative embodiment, LOS <NUM> may be configured with an outer diameter that is smaller than the inner diameter of outer tube <NUM> of IH <NUM>. Correspondingly, gripping slopes <NUM> of IH <NUM> may be configured with an inwardly sloping surface at the distal end of outer tube <NUM> (i.e., rather than an outwardly sloping surface at the distal end of inner tube <NUM>). Furthermore, gripping snap <NUM> of LOS <NUM> may be configured with a radially outward facing slope (i.e., rather than a radially inward facing slope), and locking snap <NUM> may be configured with a deflecting slope <NUM> facing proximally and radially outwards (i.e., rather than radially inwards) in such an embodiment.

The term "moving sleeve (MOS)" will be used herein to encompass both a rotating sleeve (ROS) <NUM> as in assembly <NUM> and a locking sleeve (LOS) <NUM> as in assembly <NUM>, in accordance with embodiments of the present invention.

Biasing element <NUM> may be embodied, for example, by a compression spring, or more generally by any suitable device or mechanism configured to apply an axial biasing force against LOS <NUM> and IH <NUM>.

Activation fork (AF) <NUM> of assembly <NUM> (illustrated in <FIG>) is a cylindrical tube with a hollow core and includes a pair of arc-shaped guiding arms <NUM> extending distally from an end member <NUM> at the proximal end of AF <NUM>. End member <NUM> is generally circular and "ring" shaped, i.e., with a hollow central portion, but may alternatively be a different shape or form, such as a filled (non-hollow) plate. Each guiding arm <NUM> includes an activation opening <NUM> at the proximal end adjacent to end member <NUM>. Each guiding arm <NUM> further includes a locking opening <NUM> positioned distally from and adjacent to activation opening <NUM>. It is noted that AF <NUM> may alternatively be configured with only a single guiding arm <NUM>, or more generally may be configured with any number of guiding arms <NUM>, but is described herein for exemplary purposes as including two guiding arms <NUM>.

In accordance with an alternative embodiment, gripping snap <NUM> and locking snap <NUM> of LOS <NUM> may be integrated into a single unified snap. Correspondingly, activation opening <NUM> and locking opening <NUM> of AF <NUM> may be integrated into a single unified opening. In accordance with another alternative embodiment, locking snap <NUM> of LOS <NUM> may be incorporated into internal housing <NUM> while being positioned and functioning in a manner similar to locking snap <NUM> of assembly <NUM> (illustrated in <FIG>), in which case locking opening <NUM> of AF <NUM> may be eliminated.

Syringe <NUM> of assembly <NUM> (illustrated in <FIG>) is generally identical to syringe <NUM> of assembly <NUM> (illustrated in <FIG>). Syringe <NUM> includes a syringe chamber <NUM>, a syringe flange <NUM>, a needle <NUM>, a syringe plunger rod <NUM>, a plunger stopper <NUM>, and a finger rest <NUM>. Syringe <NUM> does not include cut-outs (i.e., unlike the cutouts present on syringe <NUM> of assembly <NUM>).

<FIG> and <FIG> provide different views of safety needle assembly <NUM> in a "storage state" or a "non-deployment state", representing the configuration of assembly <NUM> when not in use (i.e., before implementing an injection). IH <NUM> is concentrically arranged within EH <NUM> and is fixedly coupled to EH <NUM> by connecting protrusions <NUM> of IH <NUM> engaging with apertures <NUM> at the proximal end of EH <NUM>. LOS <NUM> is also concentrically arranged within EH <NUM>. In particular, LOS <NUM> is disposed between outer tube <NUM> and inner tube <NUM> of IH <NUM>, where extending arms <NUM> extend through the distal end of IH <NUM>, and where gripping snaps <NUM> are positioned such that the inward slope <NUM> of each gripping snap <NUM> is supported by gripping slope <NUM> of inner tube <NUM> of IH <NUM>. Stopping protrusions <NUM> of IH <NUM> are aligned angularly with stopping protrusions <NUM> of LOS <NUM>. BE <NUM> is disposed within IH <NUM>, and supported at its distal end by base wall <NUM> of IH <NUM> and supported at its proximal end by flange wall <NUM> of LOS <NUM>.

AF <NUM> is positioned between LOS <NUM> and outer tube <NUM> of IH <NUM>. In particular, end member <NUM> at the proximal end of AF <NUM> is coupled to finger rest <NUM> of syringe <NUM>, while guiding arms <NUM> of AF <NUM> are guided by guiding ribs <NUM> on the inner part of outer tube <NUM>. The distal end of guiding arms <NUM> are positioned between gripping snap <NUM> of LOS <NUM> and outer tube <NUM> of IH <NUM>. Syringe <NUM> is positioned within inner tube <NUM> of IH <NUM> and coupled to LOS <NUM> by holding snaps <NUM>. Syringe <NUM> is concentric to LOS <NUM> by ridges <NUM> on flange wall <NUM>.

BE <NUM> applies an axial force (e.g., a spring force) that biases LOS <NUM> to the proximal direction. Gripping snaps <NUM> of LOS <NUM> are compelled by gripping slope <NUM> to deflect radially outwards when LOS <NUM> is biased to the proximal direction. When assembly <NUM> is in a storage state, guiding arms <NUM> of AF <NUM> prevents gripping snaps <NUM> from deflecting radially outwards, which in turn prevents LOS <NUM> from moving proximally. Syringe <NUM> is rotatable and axially movable but is prevented from axial movement when in storage position by holding snaps <NUM> which locks syringe flange <NUM> axially relative to LOS <NUM>. When assembly <NUM> is in a storage state, syringe needle <NUM> extends at least partially through distal opening <NUM> and is encased by a needle guard <NUM> (analogous to needle guard <NUM> of assembly <NUM>).

To deploy assembly <NUM> for performing an injection, a user (e.g., a medical clinician) holds assembly <NUM>, preferably via grip <NUM>, and removes needle guard <NUM>, such as by pulling needle guard in the <NUM> distal direction, to expose needle <NUM>. The user inserts the exposed distal end of needle <NUM> into an injection site (e.g., a body region of a patient to be injected). <FIG> is a side view illustration of safety needle assembly <NUM> during a needle insertion stage. After needle <NUM> has been inserted into the injection site, the user presses syringe finger rest <NUM> which pushes plunger rod <NUM> in the distal direction together with AF <NUM>. The distal advancement of plunger rod <NUM> mutually advances plunger stopper <NUM> within syringe chamber <NUM>, which propels the injectant substance distally within chamber <NUM> to pass through the distal aperture of needle <NUM> and enter the injection site. The progress of plunger rod <NUM> and plunger stopper <NUM> along chamber <NUM> and the passage of the injectant substance can be viewed through windows <NUM>. <FIG> is a side view illustration of safety needle assembly <NUM> during an injection stage.

The distal advancement of syringe plunger rod <NUM> continues until activation openings <NUM> of guiding arms <NUM> of AF <NUM> aligns with gripping snaps <NUM> of LOS <NUM>, and locking openings <NUM> of guiding arms <NUM> of AF <NUM> aligns with locking snaps <NUM> of LOS <NUM>. This allows gripping snaps <NUM> and locking snaps <NUM> to deflect radially outwards through the respective openings (since they are no longer prevented from such deflection by guiding arms <NUM>), causing axial movement of LOS <NUM> to the proximal direction. It is noted that gripping snaps <NUM> are slightly wider in size than locking openings <NUM>, such that when locking openings <NUM> pass gripping snaps <NUM> as syringe plunger rod <NUM> advances distally, gripping snaps <NUM> will be unable to deflect through locking openings <NUM> and LOS <NUM> will remain in a non-activated position. Syringe <NUM> and LOS <NUM> are held in place by the force applied by the user fingers pressing (distally) against finger rest <NUM> at the end of syringe plunger rod <NUM>. <FIG> is an illustration of safety needle assembly <NUM> during the end of an injection stage, including a side view, a corresponding sectional view and a detailed view, showing the respective alignments of LOS <NUM>, AF <NUM> and syringe <NUM> at this stage.

Safety needle assembly <NUM> provides a smooth and substantially constant opposing resistive force during the advancement of syringe plunger rod <NUM>, without an abrupt force increase needed to activate the safety retraction mechanism as in conventional (partially automated) safety syringes. The smooth and substantially constant resistance compels the user to fully depress syringe plunger rod <NUM> (by continuing to press against finger rest <NUM>) without prematurely terminating the distal advancement of plunger rod <NUM> along syringe chamber <NUM> before the injection process has been fully carried out and the safety mechanism has been activated. Reference is made again to <FIG>, <FIG> and <FIG> and the relevant description provided hereinabove.

After the injection process is completed, the user releases the distal force applied to syringe plunger rod <NUM> by stopping to press finger rest <NUM>, which reduces the axial force applied to syringe <NUM> and LOS <NUM>. This allows the biasing force of BE <NUM> to move LOS <NUM> axially to the proximal direction. Gripping snaps <NUM> are deflected radially outward through activation openings <NUM> until gripping snaps <NUM> pass the proximal end of inner tube <NUM> and return to their relaxed (non-deflected) position. At a certain proximal advancement of LOS <NUM>, locking snaps <NUM> engage gripping slopes <NUM> of IH <NUM> and deflect radially outward through locking openings <NUM>. The proximal motion of LOS <NUM> continues until stopping protrusions <NUM> of LOS <NUM> engage stopping protrusions <NUM> of IH <NUM>, and locking snaps <NUM> pass the proximal end of inner tube <NUM> and return to their relaxed (non-deflected) position, restricting further LOS <NUM> movement. The proximal axial movement of LOS <NUM> is accompanied by the mutual proximal axial movement of syringe <NUM>, which in turn causes syringe needle <NUM> to retract into the assembly housing (external housing <NUM> and/or internal housing <NUM>). <FIG> is an illustration of safety needle assembly <NUM> during the syringe retraction stage, including a side view, a sectional view, and a detailed view thereof.

After syringe <NUM> has been fully retracted such that needle <NUM> is completely positioned within EH <NUM> and/or IH <NUM>, stopping protrusions <NUM> of IH <NUM> prevents further proximal motion of LOS <NUM> and syringe <NUM> when engaged with stopping protrusions <NUM>, while locking snaps <NUM> prevents distal motion of LOS <NUM> and syringe <NUM>. This places assembly <NUM> in a "safe discard state", allowing the user to safely dispose of needle <NUM> and assembly <NUM>. <FIG> and <FIG> are illustration of safety needle assembly <NUM> in a discard state, including respective side views, sectional views, and detailed views thereof.

Reference is now made to Figures <NUM> through <NUM>, which collectively illustrate a safety needle assembly, generally referenced <NUM>, according to a third embodiment of the present invention. Assembly <NUM> includes an external housing (EH) <NUM>, an internal housing (IH) <NUM>, a locking sleeve (LOS) <NUM>, a biasing element (BE) <NUM>, an activation fork (AF) <NUM>, a syringe <NUM>, and an outer cap <NUM>. Assembly <NUM> has a distal end and a proximal end, which is depicted in <FIG> in the context of external housing <NUM>, where the distal end faces away from the user holding assembly <NUM> and towards the injection site. Assembly <NUM> is also defined by a longitudinal axis, extending lengthwise along the assembly between the proximal and distal ends, where an "axial" direction corresponds to a direction parallel to the longitudinal axis (i.e., towards or away from the proximal or distal ends), whereas a "radial" direction corresponds to a direction orthogonal to the longitudinal axis, and extending radially therefrom.

External housing (EH) <NUM> of assembly <NUM> (illustrated in <FIG>) is generally analogous to EH <NUM> of assembly <NUM> (illustrated in <FIG>). EH <NUM> of assembly <NUM> (illustrated in <FIG>), but is adapted to engage with IH <NUM> via a pair of snaps <NUM> as described hereinbelow. EH <NUM> is configured to at least partially encase the other components of assembly <NUM>. EH <NUM> includes a proximal EH body portion <NUM> which is substantially cylindrical shaped (i.e., having a substantially circular radial cross-section), and a distal EH body portion <NUM> which is tubular having a substantially rectangular radial cross-section with a pair of arc-shaped edges. EH <NUM> includes at least one grip <NUM> disposed at a proximal end thereof for enabling a user to hold or grip assembly <NUM> and facilitate the needle insertion. EH <NUM> further includes a flange <NUM>, consisting of opposing ledges projecting radially outward at the proximal end of EH <NUM>, for positioning the fingers of a user when depressing the syringe plunger during an injection. A pair of windows <NUM> are arranged lengthwise along the distal EH body portion <NUM> between grip <NUM> and the distal end of EH <NUM>, to allow observation of the injectant substance throughout the injection process. EH <NUM> includes a pair of snaps <NUM> disposed on opposite sides of proximal EH body portion <NUM>, to hold IH <NUM> in place. EH <NUM> includes a distal opening <NUM>, through which the syringe needle passes during an injection. EH <NUM> further includes a plurality of distal ribs <NUM>, arranged on the inner surface of distal EH body portion <NUM>, and configured to radially support syringe hub <NUM> (as will be discussed further hereinbelow with reference to <FIG>). A plurality of support ribs <NUM> protrude radially from a proximal opening at the proximal end of EH <NUM>, and is configured to support guiding arms of activation fork <NUM> (as will be discussed further hereinbelow with reference to <FIG>) and to prevent rotation of IH <NUM> within EH <NUM>. The distal end of EH <NUM> is characterized by a distal EH tube <NUM> having a pair of thick slots <NUM> and a pair of thin slots <NUM> extending longitudinally along the outer circumferential surface of distal EH tube <NUM> and opposingly disposed. In particular, thick slots <NUM> are disposed symmetrically on opposing sides of distal EH tube <NUM>, while thin slots <NUM> are disposed symmetrically on opposing sides in between thick slots <NUM>. A respective thick slot indentation <NUM> extends radially inward from the proximal end of each thick slot <NUM>, and is configured to engage a corresponding protrusion <NUM> of outer cap <NUM> (as will be discussed further hereinbelow with reference to <FIG>).

Internal housing (IH) <NUM> of assembly <NUM> (illustrated in <FIG>) is generally analogous to IH <NUM> of assembly <NUM> (illustrated in <FIG>). IH <NUM> includes an inner tube <NUM> concentrically disposed within an outer tube <NUM>, where inner tube <NUM> is affixed to outer tube <NUM> via a plurality of (e.g., four) radially extending connecting ribs <NUM>. A base wall <NUM> is positioned within inner tube <NUM>. Guiding ribs <NUM> are situated on opposite sides on the inner part of outer tube <NUM>. IH <NUM> further includes a pair of locking snaps <NUM>, located distally of outer tube <NUM> on a distally extending portion <NUM> of inner tube <NUM>, and extending axially on opposite sides. IH <NUM> is characterized by a distal end <NUM>. Each locking snap <NUM> includes a locking tooth <NUM> at a proximal end thereof. Locking tooth <NUM> may be characterized by a triangular protrusion extending radially outwards from the respective locking snap <NUM>. When assembly <NUM> is in a storage position, each locking tooth <NUM> is positioned within a first locking window <NUM> of arms <NUM> of locking sleeve <NUM> (as will be described further hereinbelow with reference to <FIG>). A pair of openings <NUM> are located on opposing sides of outer tube <NUM>. IH <NUM> is positioned within proximal EH body portion <NUM> of EH <NUM>. In particular, snaps on proximal EH body portion <NUM> engage with respective IH openings <NUM> of outer tube <NUM>, so as to couple IH <NUM> to EH <NUM>. Gripping slopes <NUM> are located on opposing sides of inner tube <NUM>, where each gripping slope <NUM> is characterized by an outwardly sloping surface near the distal end of inner tube <NUM>. It is noted that IH <NUM> does not include connecting protrusions or stopping protrusions, in contrast to IH <NUM> of assembly <NUM>.

It is further noted that the "external housing" and the "internal housing" can be considered two parts of a single component which can be collectively referred to as a "housing". Accordingly, external housing <NUM> and internal housing <NUM> are represented herein as two separated pieces or components for convenience of manufacturing considerations, but can alternatively can be manufactured as a single integral component using different manufacturing technologies.

Locking sleeve (LOS) <NUM> of assembly <NUM> (illustrated in <FIG>) is similar to LOS <NUM> of assembly <NUM> (illustrated in <FIG>). LOS <NUM> is tubular shaped with a hollow cylindrical body having an inner diameter and axial length larger than inner tube <NUM> of IH <NUM>. LOS <NUM> includes a pair of extending arms <NUM> extending distally from a cylindrical wall <NUM> at the proximal end of LOS <NUM>. Each extending arm <NUM> includes a gripping snap <NUM> at the proximal end of LOS <NUM>. Gripping snap <NUM> has a radially inward facing slope <NUM> at the distal end thereof. Each extending arm <NUM> further includes a first locking window <NUM> positioned adjacent to and distally of the respective gripping snap <NUM>, and a second locking window <NUM> positioned distally of first locking window <NUM> at the distal end of extending arm <NUM>. Locking windows <NUM>, <NUM> are openings extending through the respective extending arms <NUM> and configured to accommodate the locking tooth <NUM> and locking snap <NUM> of IH <NUM> when assembly <NUM> is in a storage position or a discard state. A pair of holding snaps <NUM> are positioned on cylindrical wall <NUM>, projecting distally from opposing bridge portions <NUM> connecting the arcuate ridges of cylindrical wall <NUM>. A stopping protrusion <NUM> is positioned at the distal end of each extending arm <NUM> adjacent to the respective second locking window <NUM>. Stopping protrusion <NUM> faces radially inwards and includes a proximally facing ridge <NUM> and an axially parallel wall <NUM>. LOS <NUM> is fitted over inner tube <NUM> of IH <NUM> when assembly <NUM> is in a storage position, such that extending arms <NUM> extend pass the distal end of IH <NUM> and are positioned between connecting ribs <NUM>, and such that slope <NUM> of a respective gripping snap <NUM> is engaged with a corresponding gripping slope <NUM> of inner tube <NUM>. Furthermore when assembly <NUM> is in a storage position, each locking tooth <NUM> of IH <NUM> is positioned within a respective first locking window <NUM> of LOS <NUM>.

While certain components of LOS <NUM> are described for exemplary purposes as being of a plurality, LOS <NUM> may more generally be configured with any number of these respective components. LOS <NUM> may alternatively be configured with an outer diameter smaller than the inner diameter of outer tube <NUM> of IH <NUM>. Correspondingly, gripping slopes <NUM> of IH <NUM> may be configured with an inwardly sloping surface at the distal end of outer tube <NUM> (i.e., rather than an outwardly sloping surface at the distal end of inner tube <NUM>). Furthermore, gripping snap <NUM> of LOS <NUM> may be configured with a radially outward facing slope (i.e., rather than a radially inward facing slope <NUM>). The term "moving sleeve (MOS)" as used herein further encompasses a locking sleeve (LOS) <NUM> in accordance with embodiments of the present invention.

Biasing element (BE) <NUM> (shown for example in <FIG> and <FIG>) may be embodied by a compression spring, or more generally by any suitable device or mechanism configured to apply an axial biasing force against LOS <NUM> and IH <NUM>.

Activation fork (AF) <NUM> of assembly <NUM> (illustrated in <FIG>) is similar to AF <NUM> of assembly <NUM> (illustrated in <FIG>). AF <NUM> is tubular shaped with a hollow cylindrical body and includes a pair of arc-shaped guiding arms <NUM> extending distally from an end member <NUM> at the proximal end of AF <NUM>. End member <NUM> is generally circular and ring-shaped (i.e., having a hollow central core), but may be an alternative shape or form (e.g., such as a filled non-hollow plate). Each guiding arm <NUM> includes an activation opening <NUM> at the proximal end adjacent to end member <NUM>. End member <NUM> includes a groove <NUM>, such as a circular groove, on the inner surface thereof. It is noted that AF <NUM> does not include locking openings on each guiding arm, in contrast to AF <NUM> of assembly <NUM>. While certain components of AF <NUM> are described for exemplary purposes as being of a plurality, AF <NUM> may more generally be configured with any number of these respective components (e.g., having fewer or greater than two guiding arms <NUM>).

Syringe <NUM> of assembly <NUM> (illustrated in <FIG>) is similar to syringe <NUM> of assembly <NUM> (illustrated in <FIG>) and syringe <NUM> of assembly <NUM> (illustrated in <FIG>). Syringe <NUM> includes a syringe chamber <NUM>, a syringe plunger rod <NUM>, a syringe hub <NUM>, a needle <NUM>, a needle guard <NUM>, and a plunger stopper <NUM>. Syringe chamber <NUM> has a hollow cylindrical body with a chamber flange <NUM> at its proximal end. Plunger rod <NUM> is a cylindrical rod positioned concentrically within the hollow body of syringe chamber <NUM> with a finger rest <NUM> at its proximal end. The distal end of plunger rod <NUM> is coupled to plunger stopper <NUM>, which is located within the hollow body of syringe chamber <NUM> so as to seal syringe chamber <NUM> from its proximal end. Needle <NUM> extends distally from the distal opening of syringe hub <NUM> at the distal end of syringe chamber <NUM>, and is covered by needle guard <NUM> when assembly <NUM> is not in use. Plunger rod <NUM> is longitudinally advanceable within syringe chamber <NUM>, such that when plunger rod <NUM> is compelled in a distal direction, such as by pressing against finger rest <NUM>, an injectant substance contained within syringe chamber <NUM> is propelled distally by plunger stopper <NUM> through needle <NUM>.

Syringe hub <NUM> includes a proximal hollow body portion <NUM> and a distal hollow body portion <NUM>. A female screw <NUM> on the inner surface of proximal hollow body portion <NUM> is screwed around a male screw <NUM> of syringe chamber <NUM>, thus engaging syringe hub <NUM> to syringe chamber <NUM>. Syringe hub <NUM> further includes an internal sleeve <NUM> which engages the inner side of the hollow cylindrical body of syringe chamber <NUM> in a manner that seals the two against each other. Needle <NUM> is contained within distal hollow body portion <NUM> of syringe hub <NUM>. Syringe hub <NUM> further includes two hub teeth <NUM> located on the proximal end thereof. When syringe hub <NUM> is engaged to syringe chamber <NUM>, hub teeth <NUM> are positioned within notches <NUM> of a ring <NUM> of syringe chamber <NUM>, so as to prevent hub <NUM> from being unscrewed from syringe chamber <NUM>.

Needle guard <NUM> is illustrated in further detail in <FIG>. Needle guard <NUM> includes a short cylindrical tube <NUM> which is opened at its proximal end and closed at its distal end. Needle <NUM> is encased within cylindrical tube <NUM>, which overlaps the distal hollow portion <NUM> of syringe hub <NUM> at its proximal end so as to seal distal hollow portion <NUM>. Needle guard <NUM> further includes a proximal ring <NUM> and a distal ring <NUM> radially encircling the outer circumferential surface of needle guard <NUM>, where the diameter of distal ring <NUM> is smaller than that of proximal ring <NUM>. Proximal ring <NUM> and distal ring <NUM> are configured to facilitate engagement of needle guard <NUM> and outer cap <NUM> as will be elaborated upon hereinbelow. It is appreciated that needle guard <NUM> is directed to prevent contamination or needlestick injury from an exposed needle <NUM>, and acts as a barrier for the injectant substance in syringe chamber <NUM> when assembly <NUM> is in a storage state.

Outer cap <NUM> is illustrated in <FIG>. Outer cap <NUM> is positioned at the distal end of EH <NUM>. Outer cap <NUM> includes a hollow cap body <NUM> and a hollow cap tube <NUM>. Cap tube <NUM> is positioned proximally of cap body <NUM> and separated by a connecting wall <NUM>, and cap tube <NUM> has a smaller diameter than cap body <NUM>. Outer cap <NUM> includes a pair of thick ribs <NUM> and a pair of thin ribs <NUM> extending longitudinally on the outer circumferential surface of cap tube <NUM>, such that thick ribs <NUM> are disposed symmetrically on opposite sides of cap tube <NUM>, and thin ribs <NUM> are positioned orthogonal to thick ribs <NUM> and disposed symmetrically on opposite sides. A respective thick rib protrusion <NUM> extends radially outward from the proximal end of each thick rib <NUM> and is configured to engage a corresponding indentation <NUM> of thick slot <NUM> of distal EH tube <NUM> when assembly <NUM> is in a storage position to prevent detachment of outer cap <NUM> from EH <NUM>. Outer cap <NUM> further includes two cap snaps <NUM> located within cap body <NUM>. Cap snaps <NUM> extend distally from the inner portion of connecting wall <NUM> and are inclined radially inward. The outer surface of cap body <NUM> includes pulling grips <NUM> to facilitate manual pulling of outer cap <NUM>. While certain components of outer cap <NUM> are described for exemplary purposes as being of a plurality, outer cap <NUM> may more generally be configured with any number of these respective components, such as having fewer than or more than two thick ribs <NUM> or thin ribs <NUM> or cap snaps <NUM>. It is appreciated that one function of outer cap <NUM> may be to facilitate the distal pulling of needle guard <NUM> so as to expose needle <NUM> prior to deployment of syringe assembly <NUM>. Another function of outer cap <NUM> may be to transfer energy shock directly to EH <NUM> so as to protect syringe <NUM> upon external impact of assembly <NUM>, such as if assembly <NUM> is dropped.

<FIG> and <FIG> provide different views of safety needle assembly <NUM> in a storage state or a non-deployment state, representing the configuration of assembly <NUM> when not in use (i.e., before implementing an injection). IH <NUM> is disposed concentrically within EH <NUM> and is fixedly coupled to EH <NUM> by snaps <NUM> on proximal EH body portion <NUM> engaging with the respective connection openings <NUM> of IH outer tube <NUM>. LOS <NUM> is also disposed concentrically within EH <NUM>. LOS <NUM> is disposed between outer tube <NUM> and inner tube <NUM> of IH <NUM>, with extending arms <NUM> extending past the distal end of IH <NUM>, and with gripping snaps <NUM> positioned such that the inward slope <NUM> of each gripping snap <NUM> is supported by an opposing gripping slope <NUM> of inner tube <NUM>. Stopping protrusions <NUM> of LOS <NUM> are aligned angularly with locking snaps <NUM> of IH <NUM>. Locking teeth <NUM> of IH <NUM> are positioned within first locking windows <NUM> on guiding arms <NUM> of LOS <NUM>. BE <NUM> is disposed within IH <NUM>. BE <NUM> is supported at its distal end by base wall <NUM> of IH <NUM>, and supported at its proximal end by flange wall <NUM> of LOS <NUM>. BE <NUM> applies a biasing axial force that biases LOS <NUM> to the proximal direction, and compels gripping snaps <NUM> of LOS <NUM> to deflect radially outwards by gripping slope <NUM> of IH <NUM>. However, the radial outward deflection of gripping snaps <NUM> is prevented by AF <NUM>, as described further hereinbelow.

AF <NUM> is positioned between LOS <NUM> and outer tube <NUM> of IH <NUM>. End member <NUM> of AF <NUM> is coupled to finger rest <NUM> of syringe <NUM>, by groove <NUM> on inner surface of end member <NUM> engaging with a cylindrical outward facing protrusion <NUM> on finger rest <NUM>. Guiding arms <NUM> of AF <NUM> are guided by connecting ribs <NUM> of IH <NUM>, and are positioned between gripping snaps <NUM> of LOS <NUM> and guiding ribs <NUM> on inner surface of outer tube <NUM> of IH <NUM>. Guiding arms <NUM> are also supported by support ribs <NUM> protruding radially from the inner surface proximal end of proximal EH body portion <NUM>, preventing the radial deflection of gripping snaps <NUM>, which in turn prevents LOS <NUM> from being displaced proximally by the biasing force applied by BE <NUM>.

Syringe <NUM> is disposed concentrically within inner tube <NUM> of IH <NUM>. Barrel flange <NUM> of syringe chamber <NUM> is positioned between flange wall <NUM> and holding snaps <NUM> of LOS <NUM>, which prevents axial movement of syringe <NUM> relative to LOS <NUM>. Syringe needle <NUM> extends at least partially through distal opening <NUM> and is encased by needle guard <NUM>. Outer cap <NUM> covers needle guard <NUM> distally of EH <NUM>. Cap tube <NUM> of outer cap <NUM> is positioned within EH distal tube <NUM> of EH <NUM>, and cap body <NUM> is positioned distally of EH distal opening <NUM>, such that connecting wall <NUM> effectively prevents outer cap <NUM> from being fully enveloped within EH <NUM>. Thick ribs <NUM> and thin ribs <NUM> on cap tube <NUM> are correspondingly positioned within respective thick slots <NUM> and thin slots <NUM> on EH distal tube <NUM>, thereby rotationally orienting outer cap <NUM> in a specific manner in relation to EH <NUM>. The greater thickness of thick ribs <NUM> relative to thin ribs <NUM> prevents outer cap <NUM> from engaging with EH <NUM> differently from the intended manner, such as in a perpendicular orientation, since thick ribs <NUM> are physically incapable of embedding within thin slots <NUM> of EH distal tube <NUM>. Furthermore, thick rib protrusions <NUM> are embedded within corresponding thick slot indentations <NUM> of EH distal tube <NUM>, so as to prevent outer cap <NUM> from disengaging from EH <NUM> (without applying a sufficient distal axial pulling force on outer cap <NUM>). Needle guard <NUM> is positioned distally of EH <NUM> within outer cap <NUM>, such that the distal end of outer cap <NUM> is distal of the distal end of needle guard <NUM>. The distal end of cap snaps <NUM> are positioned proximal of distal ring <NUM> of needle guard <NUM>, and the inner portion of connecting wall <NUM> is positioned distal of proximal ring <NUM> of needle guard, thus coupling outer cap <NUM> with needle guard <NUM>. When outer cap <NUM> is pulled distally so as to expose needle <NUM> prior to insertion, the distal end of cap snaps <NUM> engages with distal ring <NUM> so as to distally pull needle guard <NUM> along with outer cap <NUM>. After their removal from EH <NUM> and syringe <NUM>, needle guard <NUM> and outer cap <NUM> remain integrally coupled to one another, as cap snaps <NUM> are fixedly embedded between proximal ring <NUM> and distal ring <NUM>.

To deploy assembly <NUM> for performing an injection, a user (e.g., a medical clinician) holds assembly <NUM>, such as via grip <NUM>. The user removes needle guard <NUM> by pulling outer cap <NUM> in a distal direction, such as via pulling grips <NUM>. The pulling of outer cap <NUM> compels thick rib protrusions <NUM> to disengage from respective thick slot indentations <NUM> of EH distal tube <NUM>, and cap snaps <NUM> to engage with distal ring <NUM> of needle guard <NUM>, thereby pulling needle guard <NUM> distally along with outer cap <NUM> so as to expose needle <NUM>. As needle guard <NUM> is pulled, the inner surface of hub tube <NUM> slides off the outer surface of distal hub body portion <NUM> of syringe hub <NUM>. Following their removal, needle guard <NUM> remains encased within outer cap <NUM> by cap snaps <NUM> being fixedly embedded between proximal ring <NUM> and distal ring <NUM> of needle guard <NUM>.

The user inserts the exposed distal end of needle <NUM> into an injection site (e.g., a body region of a patient to be injected), such as by holding EH <NUM> at grip <NUM> and pushing needle <NUM> into the injection site. After needle <NUM> has been inserted, the user presses syringe finger rest <NUM> distally while applying a counterforce against EH flange <NUM>, compelling axial movement of plunger rod <NUM> in the distal direction together with AF <NUM>. The distal advancement of plunger rod <NUM> mutually advances plunger stopper <NUM> within syringe chamber <NUM>, which propels the injectant substance distally within chamber <NUM> to pass through the distal aperture of needle <NUM> and enter the injection site. The progress of plunger rod <NUM> and plunger stopper <NUM> along chamber <NUM> and the passage of the injectant substance can be viewed through windows <NUM> of EH <NUM>. <FIG> illustrates safety needle assembly <NUM> during an injection stage.

Toward the end of the injection, when plunger stopper <NUM> has reached a position adjacent to internal sleeve <NUM> of syringe hub <NUM> and the injectant substance is nearly completely administered, activation openings <NUM> of guiding arms <NUM> of AF <NUM> align with gripping snaps <NUM> of LOS <NUM>. This allows gripping snaps <NUM> to deflect radially outwards through the respective activation openings <NUM> (since they are no longer prevented from such deflection by guiding arms <NUM>), compelling an axial displacement of LOS <NUM> to the proximal direction (due to the biasing force applied by BE <NUM>). Syringe <NUM> and LOS <NUM> are held in place by the clamping force applied by the user pressing against finger rest <NUM> and against EH flange <NUM>, allowing the user to complete the injection. <FIG> illustrates safety needle assembly <NUM> during a syringe activation or end of injection, showing the respective alignments of LOS <NUM>, AF <NUM> and syringe <NUM> at this stage.

After the injection process is completed and the injectant substance is fully administered, the user releases the distal force applied to syringe plunger rod <NUM> by reducing the clamping force between finger rest <NUM> and EH flange <NUM>. This gradually reduces the axial force applied to syringe <NUM> and LOS <NUM>, allowing the biasing force of BE <NUM> to move LOS <NUM> axially to the proximal direction. As LOS <NUM> moves proximally, gripping snaps <NUM> are deflected radially outward through activation openings <NUM> (due to the interaction between inward slope <NUM> of LOS <NUM> and gripping slope <NUM> of IH <NUM>), until gripping snaps <NUM> pass the proximal end of inner tube <NUM>, allowing gripping snaps <NUM> to return to their relaxed (non-deflected) position. At a certain proximal advancement of LOS <NUM>, locking snaps <NUM> of IH <NUM> engage first locking windows <NUM> of LOS <NUM> and deflect radially inwards, allowing for further advancement of LOS <NUM>.

The proximal motion of LOS <NUM> continues until proximally facing ridges <NUM> of stopping protrusions <NUM> of LOS <NUM> engages distal end <NUM> of IH <NUM>. At this point, locking snaps <NUM> of IH <NUM> are aligned such that locking teeth <NUM> are positioned within second locking windows <NUM> of LOS <NUM> and no longer supported by guiding arms <NUM>, allowing locking snaps <NUM> to return to their relaxed (non-deflected) position, restricting further LOS <NUM> movement. The proximal axial movement of LOS <NUM> is accompanied by the mutual proximal axial movement of syringe <NUM>, due to the engagement of barrel flange <NUM> with flange wall <NUM>, which in turn causes syringe hub <NUM> and syringe needle <NUM> to retract (proximally) into the assembly housing (EH <NUM> and/or IH <NUM>) through opening <NUM>. As syringe hub <NUM> retracts, proximal hub body portion <NUM> is guided by distal ribs <NUM> of distal EH body portion <NUM>. At the end of the syringe retraction, needle <NUM> is completely positioned within the assembly housing, such that the distal end of needle <NUM> is proximal of the distal end of EH <NUM> and/or IH <NUM>. <FIG> illustrates safety needle assembly <NUM> during a syringe retraction stage.

When syringe <NUM> is fully retracted, the engagement of the proximal end of locking teeth <NUM> with the proximal end of second locking windows <NUM> prevents LOS <NUM> and syringe <NUM> from moving distally and re-exposing needle <NUM> through distal opening <NUM>. The engagement of IH distal end <NUM> with proximally facing ridges <NUM> of stopping protrusions <NUM> prevents LOS <NUM> and syringe from moving proximally and exposing needle <NUM> through the proximal end of EH <NUM>. Syringe <NUM> is prevented from disengaging from LOS <NUM> due to the interaction between barrel flange <NUM> and flange wall <NUM> from the distal side and holding snaps <NUM> from the proximal side. The engagement of axially parallel walls <NUM> of stopping protrusions <NUM> with the inner surface of distally extending portion <NUM> of inner tube <NUM> of IH <NUM> prevents guiding arms <NUM> from being deflected radially outwards. Syringe needle <NUM> is now locked in its entirety within EH <NUM> as can be viewed through EH windows <NUM>. This places assembly <NUM> in a discard state, allowing for safe disposal of needle <NUM> and assembly <NUM>. <FIG> illustrates safety needle assembly <NUM> during a discard state.

It will be appreciated that the disclosed safety needle assemblies (<NUM>, <NUM>, <NUM>) provides for automatic retraction of the needle (<NUM>, <NUM>, <NUM>) after the injection has been completed, while avoiding premature termination of the injection process, and avoiding non-activation of the safety retraction mechanism, while still providing the user with an indication of how and when the injection has been properly carried out.

Claim 1:
An automatically retracting safety needle assembly (<NUM>, <NUM>, <NUM>) configured to receive a syringe (<NUM>, <NUM>, <NUM>), the assembly having a distal end and a proximal end, the assembly comprising:
a housing, comprising an internal housing (IH) (<NUM>, <NUM>, <NUM>), having a base wall (<NUM>, <NUM>, <NUM>) situated at the distal end of the IH;
a moving sleeve (MOS) (<NUM>, <NUM>, <NUM>), at least partially disposed within the IH, the MOS comprising a flange wall (<NUM>, <NUM>, <NUM>), the MOS being axially movable;
a biasing element (BE) (<NUM>, <NUM>, <NUM>), disposed within the IH, the BE being supported between said base wall and said flange wall, the BE is configured to bias the MOS to the proximal direction;
said syringe, disposed in and movable axially within the IH, and coupled to the MOS, said syringe is configured to receive a plunger rod (<NUM>, <NUM>, <NUM>);
an activation fork (AF) (<NUM>, <NUM>, <NUM>), partially disposed within the IH, the AF comprising at least one guiding arm (<NUM>, <NUM>, <NUM>) , the at least one guiding arm being coupled with the IH and the MOS so as to prevent proximal motion of the MOS when the assembly is in a non-deployment state; and
a retraction mechanism (<NUM>, <NUM>, <NUM>, <NUM>; <NUM>, <NUM>, <NUM>, <NUM>; <NUM>, <NUM>, <NUM>, <NUM>), configured to automatically retract the syringe upon completion of injection,
wherein the assembly is configured to be deployed for injection by advancing the plunger rod and the AF axially in the distal direction with respect to the IH, the plunger rod advancing until the at least one guiding arm of the AF allows proximal movement of the MOS, thereby causing retraction of said syringe, wherein the distal advancement of the plunger rod is substantially constant without an abrupt increase in resistive force to overcome for activating the retraction mechanism, allowing for safe disposal of the assembly.