Abstract:
A needle protection device and a safety needle assembly are described. The needle protection device comprises a connecting portion and a protection arm rotatable relative to the connecting portion. A pair of holding members are respectively formed on a proximal end portion of the protection arm and the connecting portion and configured to engage with each other in an unretreatable manner. A pair of positioning arms are respectively formed on the proximal end portion of the protection arm and the connecting portion and formed with at least one pair of complementary snap-fitting features. The paired snap-fitting features are configured to engage each other in a separable manner. The needle protection device and the safety needle assembly not only reliably prevents medical instruments from incurring accidental needle-sticks after use and ensures such medical instruments disposable, but also exhibits a simple structure and low costs.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a national stage entry under 35 U.S.C. §371 of PCT Application No. PCT/CN2012/080666, filed Aug. 28, 2012, which claims the benefit of Chinese Application No. 201110270127.1, filed Sep. 1, 2011. The entire contents of PCT Application No. PCT/CN2012/080666 and Chinese Application No. 201110270127.1 are incorporated herein by reference. 
       TECHNICAL FIELD 
       [0002]    The present invention relates to a needle protection device, and particularly a needle protection device which can prevent a needle used in medical instruments such as a syringe and a blood collector from incurring accidental needle-sticks after use. The present invention further relates to a safety needle assembly comprising such needle protection device. 
       BACKGROUND 
       [0003]    In medical practice, medical instruments with a pointed needle are used very extensively, such as syringes and blood collectors. These medical instruments are used and treated by not only professionals in medical institutions but also non-professionals at home, e.g., a diabetes patient injects insulin on his own. 
         [0004]    Such a medical instrument as a syringe may leave its needle to be exposed outside after use and likely stick relevant persons, which causes considerable difficulty to collection and treatment thereof. Such needle-stick might cause infection of bacteria. 
         [0005]    In order to prevent occurrence of accidental needle-sticks, syringes with needles capable of being retracted after use have been proposed. However, such syringes are structurally complicated and costly. 
       SUMMARY 
       [0006]    Accordingly, in order to prevent medical instruments such as a syringe and a blood collector with a needle from incurring accidental needle-sticks after use with a simple structure and low costs, an aspect of the present invention provides a needle protection device comprising a connecting portion configured to be engaged with a needle hub of a needle, a protection arm configured to receive a needle tube of the needle therein, and a hinge member. The hinge member is connected between the connecting portion and the protection arm so that the protection arm is rotatable relative to the connecting portion. The needle protection device further comprises a pair of holding members formed on a proximal end portion of the protection arm and the connecting portion respectively. When the protection arm rotates to a full protection position in which it is most approximate to the needle tube of the needle relative to the connecting portion, the pair of holding members are configured to be engaged in an unretreatable manner. Preferrably, the needle protection device further comprises a pair of positioning arms formed on the proximal end portion of the protection arm and the connecting portion respectively. At least one pair of complementary snap-fitting features are formed on the pair of positioning arms. The at least one pair of snap-fitting features are configured to engage each other in a separable manner when the protection arm rotates to at least one middle position relative to the connecting portion, wherein the middle position is remote from the needle tube of the needle relative to the full protection position so that at the middle position, the pair of holding members are in non-engaged position, i.e., the pair of holding members are configured not to engage each other in the unretreatable manner. 
         [0007]    Another aspect of the present invention provides a safety needle assembly comprising a needle and the above-mentioned needle protection device. The needle comprises a needle tube and a needle hub. The needle hub may comprise a cone and a needle receiving portion located at a central position of a top end of the cone. The cone has a conical socket or conical fitting (female fitting) for mating with a nozzle or conical fitting (male fitting) of a syringe barrel to fix the needle hub on the syringe barrel. In an interior of the needle receiving portion is formed an inner bore for receiving the needle tube. The needle hub further comprises a plurality of ribs which are connected between an upper edge of the cone and a circumferential surface of the needle receiving portion to suspend the needle receiving portion. A front end of the rib expands radially outwardly to form a projection. 
         [0008]    In the present invention, the pair of positioning arms comprise a first positioning arm and a second positioning arm which are located on the same side of the first and second holding members and configured to be engaged with each other. 
         [0009]    Preferably, the needle protection device may comprise two pairs of positioning arms symmetrically located on both sides of the pair of holding members. The pair of holding members may comprise: a first holding member comprising a first column-like portion and an anchor formed on the first column-like portion; and a second holding member comprising one or more paws formed on an edge of a through hole. The one or more paws extend towards a center of the through hole. Distal ends of the paws, or the distal ends of the paws and the edge of the through hole which has a maximum radial dimension smaller than a maximum radial dimension of a base of the anchor. Wherein the one or more paws are configured such that the distal ends of the paws enable a front end of the anchor to pass through the through hole and catch the base of the anchor in an unretreatable manner when the protection arm rotates to the full protection position. 
         [0010]    The first holding member may be formed on the proximal end portion of the protection arm. The second holding member may be formed on the connecting portion. The through hole may be formed on the connecting portion. The paws are formed on the edge of the through hole, and extend towards a center of the through hole and are inclined towards a side opposite the side in which the first holding member lies, so that when the protection arm rotates to the full protection position, the front end of the anchor can pass through the through hole and beyond the paws, and the base thereof is caught by the paws in an unretreatable manner. 
         [0011]    Or, the first holding member may be formed on the connecting portion, and the second holding member may be formed on the proximal end portion of the protection arm. The through hole may be formed on the proximal end portion of the protection arm. The paws are formed on the edge of the through hole, and extend towards a center of the through hole and are inclined towards a side opposite the side in which the first holding member lies, so that when the protection arm rotates to the full protection position, the front end of the anchor can pass through the through hole and beyond the paws, and the base thereof is caught by the paws in an unretreatable manner. 
         [0012]    The first holding member may further comprise a second column-like portion between the anchor and the first column-like portion which has a maximum radial dimension smaller than that of the first column-like portion. The anchor is an extending tip portion, and a maximum radial dimension of the base of the anchor is larger than that of the second column-like portion. 
         [0013]    As another embodiment, the pair of holding members may comprise a first holding member formed with a hook-like portion at a free end thereof and a second holding member in the form of a plate-like hook, wherein the hook-like portion of the first holding member and the second holding member are configured to engage each other in an unretreatable manner when the protection arm rotates to the full protection device. 
         [0014]    Preferably, the first holding member may be formed on the proximal end portion of the protection arm, and the second holding member may be formed on the connecting portion. 
         [0015]    In another embodiment, the first holding member may be plate-shaped and formed on the proximal end portion of the protection arm, and the hook-like portion is formed on each of two opposite thickness surfaces of the free end thereof. The needle protection device may comprise two pairs of positioning arms symmetrically located on both sides of the first holding member. The positioning arm of each pair of positioning arms formed on the connecting portion is formed with a second holding member. The two hook-like portions of the first holding member and the two second holding members are configured to engage each other in an unretreatable manner when the protection arm rotates to the full protection device. 
         [0016]    Preferably, a widthwise dimension may gradually increase from the free end of the first holding member to the hook-like portion. 
         [0017]    Preferably, an additional hook-like portion is formed on one widthwise surface of the free end of the first holding member, an additional second holding member is formed on the connecting portion, so that the three hook-like portions of the first holding member are respectively engaged with the three second holding members in an unretreatable manner when the protection arm rotates to the full protection position. 
         [0018]    According to the present invention, each pair of positioning arms may comprise a first positioning arm and a second positioning arm. A first protrusion may be formed on an end portion of the second positioning arm extending towards the first positioning arm, a first concave may be at least formed on a path on the first positioning arm formed by movement relative to the first protrusion. The first protrusion is configured to engage with the first concave in a separable manner to position the protection arm at a first middle position (first in-use position). Therefore, the first protrusion and the first concave constitute a first pair of snap-fitting features. 
         [0019]    A second concave may be additionally formed on the path on the first positioning arm formed by movement relative to the first protrusion. The first protrusion is configured to engage with the second concave in a separable manner to position the protection arm at a second middle position (packaged position). Therefore, the first protrusion and the second concave constitute a second pair of snap-fitting features. 
         [0020]    The second positioning arm may comprise an upper second positioning arm and a lower second positioning arm. The first protrusion may be formed on an end portion of the upper second positioning arm extending towards the first positioning arm. The first protrusion is configured to engage with the first concave and the second concave in turn when the protection arm rotates in the direction of the full protection position relative to the connecting portion. 
         [0021]    A second protrusion may be formed at a lower edge of the lower second positioning arm. At least one third concave is formed on a path on the first positioning arm formed by movement relative to the second protrusion. The second protrusion is configured to engage with the third concave in a separable manner to position the protection arm at a third middle position (second in-use position). Therefore, the second protrusion and the third concave constitute a third pair of snap-fitting features. 
         [0022]    A fourth concave may be additionally formed on the path on the first positioning arm formed by movement relative to the first protrusion. The first protrusion is configured to engage with the fourth concave in a separable manner to position the protection arm at a fourth middle position (a temporary protection position) adjacent to the full protection position. When the protection arm rotates to the temporary protection position, the needle tube is located in the opening of the protection arm, and the first and the second holding members are in non-engaged position in which the holding members are configured not to engage the second holding members in an unretreatable manner. 
         [0023]    The safety needle assembly according to the present invention may further comprise a needle cap for receiving and covering said needle tube which has a lower end of the needle cap configured to be disposed around the needle receiving portion. The needle cap may comprise two flanges formed on an inner surface of the lower end of the needle cap, so that an annular groove is formed between the two flanges. The projections of the ribs are configured to be snap-fitted in the groove in a separable manner to prevent the needle cap from moving axially relative to the needle. 
         [0024]    The needle protection device and the safety needle assembly according to the present invention can not only reliably prevent medical instruments such as syringes from incurring accidental needle-sticks after use and ensure such medical instruments disposable, but also exhibit a simple structure and low costs. Additionally, according to the present invention, during transport and use of the safety needle assembly, the needle protection device can be stably positioned at various desired positions. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1  is a cross-sectional view of a safety needle assembly according to an embodiment of the present invention, with a protection arm being in a packaged position. 
           [0026]      FIG. 2  is a cross-sectional view of the safety needle assembly of  FIG. 1 , with the protection arm being in a first in-use position. 
           [0027]      FIG. 3  is a cross-sectional view of the safety needle assembly of  FIG. 1 , with the protection arm being in a second in-use position. 
           [0028]      FIG. 4  is a cross-sectional view of the safety needle assembly of  FIG. 1 , with the protection arm being in a temporary protection position. 
           [0029]      FIG. 5  is a cross-sectional view of the safety needle assembly of  FIG. 1 , with the protection arm being in a full protection position. 
           [0030]      FIG. 6  is a perspective view of a needle hub and a needle protection device of  FIG. 1  as viewed obliquely from the above. 
           [0031]      FIG. 7  is a perspective view of a needle hub and a needle protection device of  FIG. 1  as viewed from below. 
           [0032]      FIG. 8  is a side view of the needle hub and the needle protection device of  FIG. 1 . 
           [0033]      FIG. 9  is a top view of the needle hub and the needle protection device of  FIG. 1 . 
           [0034]      FIG. 10  is a right view of the needle hub and the needle protection device of  FIG. 9 . 
           [0035]      FIG. 11  is a left view of the needle hub and the needle protection device of  FIG. 9 . 
           [0036]      FIG. 12  is a bottom view of the needle hub and the needle protection device of  FIG. 9 , with a part thereof cut away. 
           [0037]      FIG. 13  is a cross-sectional view of the needle cap of  FIG. 1 . 
           [0038]      FIG. 14  is a bottom view of the needle cap of  FIG. 13 . 
           [0039]      FIG. 15  is a cross-sectional view of the needle cap analogous to  FIG. 13 , with the needle cap be rotated by an angle. 
           [0040]      FIG. 16  is a perspective view of a needle protection device according to another embodiment of the present invention. 
           [0041]      FIG. 17  is a top view of the needle protection device as shown in  FIG. 16 . 
           [0042]      FIG. 18  is a bottom view of the needle protection device as shown in  FIG. 16 . 
           [0043]      FIG. 19  is a cross-sectional view taken along the line A-A of  FIG. 17   
           [0044]      FIG. 20  is a schematic view of the needle protection device without positioning arms. 
       
    
    
     DETAILED DESCRIPTION 
       [0045]    Preferred embodiments of a needle protection device of the invention and a safety needle assembly including this needle protection device will be described in detail with reference to the accompanying drawings. 
         [0046]      FIG. 1  shows a safety needle assembly according to the present invention in a packaged state before use. The safety needle assembly comprises a needle  10 , a needle protection device and a needle cap  16 . 
         [0047]    The needle  10  comprises a needle hub  12  and a needle tube  11  mounted on the needle hub  12 . In some applications such as for injectors or syringes, the needle  10  is also called “injection needle”, and the needle tube  11  is also called a “needle”. The present invention is not directed to improvement to the needle  10  itself. Therefore, various needles needing protection after use known in the art all can be used to construct the safety needle assembly of the present invention. The safety needle assembly of the present invention may be, but not limited to one of a safety blood collection, a safety syringe assembly, a safety assembly for insulin, a safety single or dual flap butterfly needle (or called scalp needle) assembly. 
         [0048]    Also referring to  FIGS. 6 ,  8 ,  9  and  11 , in an embodiment of the present invention, the needle hub  12  comprises cone  121 . The cone  121  has a conical fitting (female fitting) for mating with a conical fitting (male fitting)  14  of a syringe barrel  15  to fix the needle hub  12  on the syringe barrel  15 . At a central position of a top end of cone  121 , the needle hub  12  further comprises a needle receiving portion  123  suspended by a plurality of ribs  122 . In an interior of the needle receiving portion  123  is formed an inner hole for receiving the needle  11 . The plurality of ribs  122  may be symmetrically arranged and connected between an upper edge of cone  121  and an outer circumferential surface of the needle receiving portion  123 . Although four ribs are shown in the figures, apparently the present invention is not limited thereto. A front end (namely, an end facing towards an inward depth of the needle cap  16 ) of the rib  122  expands radially outwardly to form a projection  124 . 
         [0049]    Referring to  FIGS. 13-15 , the needle cap  16  is a hollow member configured to receive and cover the needle tube  11 . A lower end of the needle cap  16  (namely, an end of the needle cap having an opening) is disposed around the needle receiving portion  123 , and two flanges  163  and  162  are formed on an inner surface of the needle cap, wherein a first flange  162  is closer to the lower end. A second flange  163  further away from the lower end may be larger than the first flange to abut against the front end of the rib  122 . An annular groove  165  is formed between the first flange  162  and the second flange  163 . The projection  124  of the rib  122  is configured to pass over the first flange  162  and be snap-fitted in the groove  165 , thereby preventing an axial movement of the needle cap  16  relative to the needle hub  12 , and preventing the needle cap  16  from accidentally separating from the needle hub  12  in the axial direction during transport. In use, a slight force can be applied so that the projection  124  separates from the groove  165  and passes over the first flange  162 , thereby removing the needle cap  16 . 
         [0050]    In the present invention, a separable snap-fitting means that two snap-fitting features, such as the above-described flange and groove and hereunder-described protrusion and recess, are snap-fitted together and can be separated from each other by applying a suitable force. 
         [0051]    Those skilled in the art should appreciate that the safety needle assembly of the present invention is not limited to inclusion of the above-described needle cap and needle hub, but can employ various needle hubs and needle caps known in the art. A main object of the present invention does not lie in the needle cap and the needle hub. 
         [0052]    Referring to  FIGS. 6-12 , particularly  FIG. 6 , the needle protection device comprises a connecting portion  2  configured to be engaged with the needle hub  12  and a protection arm  6  configured to be rotatably engaged with the connecting portion  2  via a hinge member  4 . 
         [0053]    The connecting portion  2  may be fixedly engaged with the needle hub  12  in any one of various known methods. For example, the connecting portion  2  may be integrally formed with the cone  121  of the needle hub  12  by injection molding, extends outwardly and widens from the side of the cone  121  to form other structures on the connecting portion. 
         [0054]    Alternatively, the connecting portion  2  is fixedly disposed around the outer circumferential surface of the needle hub  2  via an annular member (not shown). This embodiment is advantageous in that the needle protection device of the present invention can be directly applied to the conventional safety needle assemblies. 
         [0055]    The connecting portion  2  may be engaged at any desired position of the needle hub  12 . For example, the connecting portion may be engaged at a position of the cone  121  adjacent to the needle receiving portion (see  FIG. 8 ), whereby the length of the protection arm can be reduced. 
         [0056]    The hinge member  4  rotatably connecting the connecting portion  2  to the protection arm  6  may be one of various hinges known in the art, preferably a hinge formed by injection molding, such as a weakened structure. In a preferred embodiment as shown in the figures, the hinge member  4  is integral with the connecting portion  2 , or the hinge member  4  is part of the connecting portion  2 . Referring to  FIGS. 6 and 7 , the connecting portion  2  is wholly substantially fork-shaped or “Y”-shaped. Two prongs of the fork may be formed into the hinge member  4  by forming a weakened portion on each prong of the fork. Alternatively, the hinge member  4  may be integral with the protection arm  6 . Again alternatively, the hinge member  4  may be an individual part, and its two ends are respectively fixedly engaged with the connecting portion  2  and the protection arm  6  in the subsequent manufacturing procedure. 
         [0057]    The protection arm  6  is configured to be rotated relative to the needle hub  12  via the hinge member  4 , and retained at one of various desired positions, for instance, a full protection position closest to the needle tube  11  as shown in  FIG. 5 , and a first middle portion to a fourth middle position remote from the needle tube  11  as shown in  FIGS. 1-4 . 
         [0058]    What is shown in  FIG. 5  is an after-use state of the safety needle assembly, whereupon the protection arm  6  is rotated to the position closest to the needle tube  11 , namely, the full protection position, in which the needle tube  11  is fully received therein. 
         [0059]      FIG. 2  and  FIG. 3  show two in-use states of the safety needle assembly, whereupon the needle cap  16  is removed, the protection arm  6  is rotated to a position remote from the needle tube  11  (or adjacent to the needle syringe  15 ), namely, the in-use position. According to different applications, the protection arm  6  may have various different in-use positions, e.g., at an in-use position shown in  FIG. 2  (a first in-use position or the first middle position), the protection arm  6  may be at such an angle as 20° relative to a horizontal direction; at an in-use position shown in  FIG. 3  (a second in-use position or a third middle position), the protection arm  6  may be opened to the extremity, i.e., at an extreme position away from the needle tube  11  (or towards the syringe barrel  15 ). 
         [0060]      FIG. 1  shows a safety needle assembly in a packaged state before use in which a needle cap  16  covers the needle tube  11 , and the protection arm  6  is located at a position adjacent to the needle tube  11  (or the needle cap  16 ), namely, a packaged position (a second middle position). It may be appreciated that the more the protection arm  6  is adjacent to the needle tube  11  (or needle cap  16 ), the more packaging space can be saved. 
         [0061]      FIG. 4  shows a state of the safety needle assembly after liquid medicine is drawn and then transported, namely, a state in which the liquid medicine, after being drawn by the safety needle assembly, is transported from place to place. At this time, the needle tube  11  is covered by the protection arm  6 , but only located at an opening of the protection arm, i.e., the protection arm  6  is located at a temporary protection position (the fourth middle position). It can be seen that the temporary protection position is located between the full protection position and the packaged position. 
         [0062]    Referring to  FIGS. 6-9 , the protection arm  6  is an arm-like structural member having a generally “U”-shaped cross section and extending along a longitudinal axis, and comprises a bottom protection wall  63  and a pair of side protection walls  61  extending from opposite sides of the bottom protection wall  63 . In the present application, a side of the protection arm  6  which is adjacent to the needle hub in use is called a “proximal side”, whereas a side away from the needle hub is called a “distal side”. The bottom protection wall  63 , the pair of side protection walls  61 , and a first end wall  62  (proximal end potion) and a second end wall  64  respectively located at the proximal side and the distal side form an opening  60  of the protection arm  6 . 
         [0063]    For convenience of description, in the present application, a direction in which the protection arm  6  moves towards the full protection position shown in  FIG. 5  relative to the connecting portion  2  (or the needle hub  12 ) is called a “first direction” of the protection arm, and a direction in which the protection arm  6  rotates towards the second in-use position shown in  FIG. 3  is called a “second direction” of the protection arm. 
         [0064]    As most clearly shown in  FIG. 8 , the side protection wall  61  of the protection arm  6  comprises a first side protection wall  611  at the distal side, a second side protection wall  612  at the proximal side and a third side protection wall  613  between the first and second side protection walls. The first side protection wall  611  protrudes more towards the first direction relative to the second side protection wall  612 , or the first side protection wall  611  is positioned beyond the second side protection wall  612  in the first direction. The third side protection wall  613  transits from the second side protection wall  612  to the first side protection wall  611  along the first direction. This transition is preferably a smooth transition as shown in  FIG. 8 . However, this transition may not necessarily be smooth. 
         [0065]    The bottom protection wall  63  of the protection arm  6  comprises a first bottom protection wall  631  at the distal side, a second bottom protection wall  632  at the proximal side, and a third bottom protection wall  633  between the first and second bottom protection walls. The first bottom protection wall  631  protrudes more towards the first direction relative to the second bottom protection wall  632 , or the first bottom protection wall  631  is positioned beyond the second bottom protection wall  632  in the first direction. The third bottom protection wall  633  transits from the second bottom protection wall  632  to the first bottom protection wall  631  along the first direction. 
         [0066]    The first side protection wall  611  and the first bottom protection wall  631  are positioned beyond the second side protection wall  612  and the second bottom protection wall  632  in the first direction so that between a proximal portion of the protection arm  6  and the needle hub is provided a space enough to form a holding member and a positioning arm (to be described in detail in the following text). 
         [0067]    It should be appreciated that the above division of the side protection wall and the bottom protection wall are only for depiction purpose and does not mean that parts of the side protection wall and the bottom protection wall are physically separated from one another. 
         [0068]    In the example shown in  FIG. 8 , the third bottom protection wall  633  forms a stepped portion between the first and second bottom protection walls  631 ,  632 . Such third bottom protection wall  633  in a step form provides a surface on which a finger applies a force to push the protection arm  6 . 
         [0069]    As shown in  FIGS. 6-9 , a flange  65  is formed on each of both external sides of the second bottom protection wall  632  and the third bottom protection wall  633 . In an embodiment, the flange  65  may be integrally formed with the second bottom protection wall  632  and the third bottom protection wall  633 . The flange  65  can be used to safely push and press the protection arm  6  from the position shown in  FIG. 1  or  4  to the position shown in  FIG. 2  or  3 , for example, as a gripper from the packaged position to the in-use position upon drawing the liquid medicine. Besides, the flange  65  further increases the area of the third bottom protection wall  633  as a force-applying surface. The first end wall  62  can extend to both sides to flush with the edge of the flange  65 . 
         [0070]    On a surface of the second bottom protection wall  632  facing in the second direction may further be formed with a structure for increasing friction, such as anti-slip ribs  634  as shown. 
         [0071]    In a preferred embodiment, edge portions of respective walls and joints of adjacent walls may be all chamfered or filleted. 
         [0072]    As shown in  FIG. 5 , when the protection arm  6  rotates to the full protection position, the needle tube  11  of the needle  10  passes through the opening  60  of the protection arm  6  into the protection arm  6 . In order to further prevent the needle tube  11  from being separated from the protection arm  6 , referring to  FIGS. 5 ,  6 ,  9  and  11 , the protection arm  6  may further comprise a hook-shaped member  66  extending a predetermined distance from the first bottom protection wall  631  in the first direction and then bending towards the first bottom protection wall  631 . By virtue of this hook-shaped member  66 , the needle tube  11  can be easily guided into a space between the hook-shaped member  66  and the first bottom protection wall  631  and “hooked” by the hooked-shaped member  66  and thereby maintained in this space in an unretreatable manner. 
         [0073]    In a further preferred embodiment, the protection arm  6  may comprise two or more hook-shaped members  66  (two are shown in the figures). These hook-shaped members  66  are arranged in a longitudinal direction of the protection arm  6  so that their “hooks” are staggeredly opposite to one another. This staggeredly opposite arrangement facilitates more accurate guidance of the needle tube  11 . 
         [0074]    In a more preferred embodiment, referring to  FIGS. 5 ,  6 ,  9  and  11 , a pair of guide ribs  68  having a guide ramp at a top end thereof may be provided along the inside of the two first side protection walls  611  to restrain the needle tube  11  to the position of the hook-shaped member  66 . This embodiment is particularly suitable for a situation in which the needle tube  11  deforms after use. 
         [0075]    Referring to  FIGS. 6 ,  7 ,  9  and  12 , a first holding member  51  extending to the proximal side is formed on a proximally facing surface of the proximal end portion  62 . In the embodiment as shown in the figures, the first holding member  51  is substantially column-like and on the longitudinal axis of the protection arm  6 , and comprises a first column-like portion  57  on the proximal end portion  62 , a second column-like portion  56  extending from the first column-like portion  57  towards the proximal side and having a reduced radial dimension (e.g., diameter), and a tapered anchor  55  formed at the proximal side of the second column-like portion  56  and having a tip end (front end) facing towards the proximal side. A base of the anchor  55  is larger than that of the second column-like portion  56 . Therefore, the second column-like portion  56  is in fact a necked portion between the anchor  55  and the first column-like portion  57 . According to another embodiment (not shown), the second column-like portion  56  may not be provided, and the radial dimension of the base of the anchor  55  is made larger than that of the first column-like portion  57 . 
         [0076]    A through hole  50  may be formed at a substantially central position of the connecting portion  2 . Paws  53  are formed on an edge of the through hole  50 . The paws  53  extend towards a center of the through hole  50  while are inclined towards a side (the lower side of  FIG. 8 ) opposite the side in which the first holding member  51  lies. The paws  53  may comprise a plurality of paws separated by a plurality of gaps  54 . Alternatively, only one paw may be provided and occupy a portion of a circumference of the through hole  50 . Alternatively, the paws  53  are disposed around the circumference of the through hole without any gaps. Theoretically, when the paws are disposed along the circumference of the through hole  50 , so long as at least one paw is disposed at the side adjacent to the needle hub  12 , the object of the present invention can be achieved. An inner circumference (distal end) of the paws  53  or distal ends of the paws  53  and the edge of the through hole  50  define a bore allowing for passage of the end  55 . A radial dimension of the bore corresponds to the radial dimension of the second column-like portion  56  of the first holding member  51 , or to the radial dimension of the first column-like portion  57  when no second column-like portion  56  is provided. A maximum radial dimension of the bore is smaller than a maximum radial dimension of a base of the anchor  55 . The paws  53  are elastic and can elastically deform under a pressure of the anchor  55  of the first holding member  51 ; after the anchor  55  passes, the paws  53  elastically return and catches the base of the anchor  55 , thereby preventing the anchor  55  from retreating reversely. The paws  53  formed around the through hole  50  constitute a second holding member  52  for holding the first holding member  51  in an unretreatable manner to retain the protection arm  6  at the full protection position permanently and prevent the used safety needle assembly from being used again. 
         [0077]    Alternatively, the second holding member may be a boss having an inner bore and formed above the connecting portion (i.e., the upper side of  FIG. 8 , or on the side in which the first holding member of the connecting portion is located), and paws are inclined inward the inner bore around the edge of the inner bore. The anchor of the first holding member can be inserted into the inner bore and held by the paws. 
         [0078]    According to another embodiment, the first holding member  51  and the second holding member  52  may be interchanged in position, that is, the first holding member  51  is formed on the connecting portion  2 , whereas the second holding member  52  is formed on the proximal end portion. 
         [0079]    In the present invention, the anchor may be in any suitable shapes and is not limited to tapered (e.g. conical and pyramid) and hooked shape. So long as the front end of the anchor can pass through the through hole (not limited to a round through hole) defined by the edges (distal ends) of the paws, and the maximum radial dimension of the base of the anchor is larger than the maximum radial dimension of the through hole, an unretreatable engagement of the anchor and the paws can be achieved. In the present invention, the two column-like portion may be, but not limited to a cylinder or a pyramid so long as the maximum radial dimension of the second column-like portion is smaller than the maximum radial dimension of the base of the anchor. 
         [0080]    In order to retain the protection arm  6  to the packaged position, the temporary protection position and in-use position as shown in  FIGS. 1-4  as stably as possible, the needle protection device according to the present invention may further comprise a pair of positioning arms. In the embodiment as shown, two pairs of positioning arms are symmetrically located on both sides of the first and second holding members. 
         [0081]    The packaged position, the temporary protection position and the in-use position are middle positions different from the full protection position. When the protection arm  6  rotates to these middle positions, the two holding members do not engage each other in the unretreatable manner, that is, the two holding members are separatable. This aspect may be implemented by relative positions of the holding members as conventionally designed and relative positions of snap-fitting features mentioned hereunder, and will not be introduced in detail herein in the present invention. 
         [0082]    Referring to  FIGS. 1-4  and  FIGS. 6-9 ,  11  and  12 , according to a preferred embodiment of the present invention, each pair of positioning arms comprise a first positioning arm  71  and a second positioning arm  72 . The first positioning arms  71  extend towards the proximal side from both ends of the proximal end portion  62 , and their outer surfaces may flush with outer edges of the flanges  65 . The second positioning arms  72  are correspondingly formed at opposite sides of the connecting portion  2 , and each comprise an upwardly extending upper second positioning arm  721  and a downwardly extending lower second positioning arm  722 . As shown in  FIG. 8 , a direction pointed towards upper side of the figure (the side in which the first connecting member  51  is located) is “upper”, and a direction pointed towards lower side of the figure is “lower”. 
         [0083]    A plurality of pairs of separable snap-fitting features are formed between the first positioning arm  71  and the second positioning arm  72 . Each pair of snap-fitting features correspond to a desired retained position of the protection arm  6  upon snap-fitting, said position includes but is not limited to any position shown in  FIGS. 1-4 . Furthermore, by applying an appropriate force on the protection arm  6  in a rotating direction, each pair of snap-fitting feature can be separated (i.e., they are snap-fitted or engaged in a separable manner) so that the protection arm  6  may be rotated to different positions relative to the connecting portion  2 . Different pairs of snap-fitting features may be different to generate different resistance against rotation of the protection arm  6 . For example, at the packaged position as shown in  FIG. 1 , it is usually desired that the protection arm  6  can be prevented from accidental rotation due to vibration during transport. Therefore, a pair of snap-fitting features corresponding to the packaged position may be configured to generate a greater resistance upon snap-fitting. At the temporary protection position as shown in  FIG. 4 , the safety needle assembly is usually sent from one room to a nearby room of a hospital or clinic without a great vibration, so a pair of snap-fitting features corresponding to the temporary protection position may be configured to generate a smaller resistance upon snap-fitting. 
         [0084]    In a specific embodiment as shown in the figures, the upper second positioning arm  721  has an end portion extending towards the first positioning arm  71 , and a first protrusion  723  is formed at the end portion. A second protrusion  724  is formed at a lower edge of the lower second positioning arm  722 . Three concaves  711 ,  712  and  713  are formed on a surface of the first positioning arm  71 . The first concave  711 , the second concave  712  and a groove  714  to be mentioned hereunder are located on a movement trajectory or path of the first protrusion  723  on the positioning arm  71  relative to the positioning arm  71 ; the third concave  713  is located on a movement trajectory of the second protrusion  724  on the positioning arm  71  relative to the positioning arm  71 . 
         [0085]    The first concave  711  is located at a proximal top end of the positioning arm  71 , and opens at an edge of an upper surface to facilitate entry of the first protrusion  723  into the first concave  711 . However, the first concave  711  may not necessarily open on the upper surface. The first concave  711  and the first protrusion  723  constitute a first pair of snap-fitting features, and when they are snap-fitted, the protection arm  6  is positioned at the first in-use position as shown in  FIG. 2 . 
         [0086]    Relative to the first concave  711 , the second concave  712  is formed downstream a movement trajectory of the first protrusion  723  relative to the positioning arm  71 , i.e., formed at a downward distal position. The second concave  712  and the first protrusion  723  constitute a second pair of snap-fitting features, and when they are snap-fitted together, the protection arm  6  is positioned at the packaged position as shown in  FIG. 1 . 
         [0087]    According to a preferred embodiment of the present invention, a groove  714  is formed downstream of the second concave  713  on the positioning arm  71 . A beginning end of the groove  714  (an end adjacent to the second concave  712 ) can be a fourth concave (not shown). The first protrusion  723  and the fourth concave at the beginning end of the groove  714  constitute a fourth pair of snap-fitting features, and when they are snap-fitted together, the protection arm  6  is positioned at the temporary protection position shown in  FIG. 4 . As above discussed, the fourth concave may be shallower than other concaves. 
         [0088]    After the safety needle assembly is used, and when the protection arm  6  is rotated to the full protection position as shown in  FIG. 5 , the first protrusion  723  may be configured to slide in the groove  714  so as to reduce a force needed to rotate the protection arm  6 . The sliding engagement of the first protrusion  723  and the groove  714  may also guide the movement of the protection arm  6 , and facilitates accurate engagement of the first holding member  51  and the second holding member  52 . 
         [0089]    The third concave  713  may be formed at a proximal lower end of the positioning arm  71 , and opens at an edge of a lower surface as shown in the figure. However, the third concave  713  may not necessarily open on the lower surface. The third concave  713  and the second protrusion  723  constitute a third pair of snap-fitting features, and when they are snap-fitted together, the protection arm  6  is positioned at the second in-use position as shown in  FIG. 3 . 
         [0090]    As a preferred embodiment, snap-fitting between respective pairs of snap-fitting features is an elastic snap-fitting, which may be implemented by cantilever structure of the two positioning arms  71  and  72 , alternatively or additionally by use of elastic material to manufacture the positioning arms. Alternatively, only one of the two positioning arms  71  and  72  may be elastic. When the protrusion is not located in the concave, elastic deformation will occur between the two positioning arms  71  and  72  due to mutual pressure because of existence of protrusions; when the protrusion moves to the position of the concave, the two positioning arms return their original shapes due to elasticity, and press the protrusion into the concave, thereby positioning the protection arm  6  at a desired position. When a force is applied to the protection arm  6  in a movement direction of the protection arm  6 , if the force is sufficient to overcome a resistance caused by elastic deformation of the positioning arms, the protrusion will be separated from the concave. Then, the protection arm  6  begins to rotate until a next position. 
         [0091]    Alternatively, the first protrusion  723  may be replaced by an concave, and the first and second concaves  711  and  712  may be replaced by protrusions accordingly; or the second protrusion  724  may be replaced by an concave, and the third concave  713  may be replaced by a protrusion accordingly. 
         [0092]    The protrusion and concave may be semi-spherical or crown-shaped, or other shapes. 
         [0093]    Referring to  FIGS. 6-12 , the first positioning arm  71  extending from the proximal end portion of the protection arm  6  is attached to the connecting portion  2  via the hinge member  4 . In other embodiment, the hinge member may be used as part of the first positioning arm. 
         [0094]    The hinge member  4  and the second positioning arm  72  may be respectively located at inner and outer sides of the first positioning arm  71 . For example, in the embodiment as shown in the figures, the second positioning arm  72  is located at the inner side of the first positioning arm  71 , and the hinge member  4  is fixedly attached to an outer side surface of the first positioning arm  71 . 
         [0095]    The positioning arms can be embodied as any other form of positive fit. Alternatively, the positioning arms can be held at any position relative to the protection arm  6  by for example friction force resulted by the tight fit therebetween. Certainly, the positioning arms can be even removed as shown in  FIG. 20 . 
         [0096]    The needle protection device according to the present invention may be a plane-symmetrical structure which is substantially symmetrical relative to a plane (symmetrical plane) in which the longitudinal axis of the protection arm lies (for example, the hook-shaped members  66  and ribs  124  may not be symmetrically distributed relative to the symmetrical plane), wherein the first and second holding members  51  and  52  are located on the symmetrical plane, and respective protection walls and positioning arms are symmetrically distributed relative to the symmetrical plane. In the present invention, the term “inner” means a direction pointing at the symmetrical plane or approaching the symmetrical plane, and “outer” means a direction away from the symmetrical plane or remote from the symmetrical plane. 
         [0097]    The protection arm structure of the present invention does not need to use a mold with a slide upon injection molding, thereby simplifying the structure of the mold, substantially improving the number of mold cavities (e.g., up to 96 cavities), greatly facilitating use of a large mold to mass produce molded products by one injection molding, and remarkably reducing the production costs of the protection arm. Furthermore, there are low mold-opening requirements for the protection arm structure of the present invention, which facilitates simplification of the mold structure and reduction of manufacturing and use costs of the mold. 
         [0098]      FIGS. 16-19  show a needle protection device according to another embodiment of the present invention. The needle protection device is similar to the above-mentioned needle protection device. Therefore, the same reference numerals are used to denote the same portions or members. The difference between the needle protection device and the above-mentioned needle protection device is that the first holding member  51  with the tapered anchor  55  and the second holding member  52  formed by the paws  53  may be replaced by a hook-like member. In such a case, the through hole  50  may be omitted. According to the teaching of the present invention, those skilled in the art can contemplate that the hook-like holding members may also be replaced by other members known by those skilled in the art which can be engaged in an unretreatable manner. 
         [0099]    In the embodiment as shown in  FIGS. 16-19 , a pair of holding members comprise a first holding member  81  and a second holding member  82 . A hook-like portion  85  is formed at a free end  86  of the first holding member  81 ; the second holding member  82  is a plate-like hook, i.e., a cross-sectional shape of the plate material is hook-like (as can be best seen in  FIG. 19 ). The hook-like portion  85  of the first holding member  81  and the second holding member  82  are configured such that they can be engaged in an unretreatable manner when the protection arm  6  rotates to the full protection position shown in  FIG. 5 . 
         [0100]    In the preferred embodiment as shown in the figures, the first holding member is also plate-shaped and formed on the proximal end portion  62  of the protection arm  6 , and has two opposite widthwise surfaces  84  and two opposite thickness surfaces  83 . The hook-like portion  85  is formed on each of the two thickness surfaces  83  at the free end  86  of the first holding member  81 . 
         [0101]    Referring to  FIG. 16 , two pairs of positioning arms are symmetrically located on both sides of the first holding member  81 . The positioning arm  72  of each pair of positioning arms formed on the connecting portion  2  is each formed with a second holding member  82 . When the protection arm  6  rotates to the full protection position, the two hook-like portions  85  of the first holding member  81  and the two second holding members  82  are respectively engaged in an unretreatable manner. 
         [0102]    As shown in  FIGS. 16-18 , the free end  86  of the first holding member  82  forms a substantially tapered shape, i.e., a widthwise dimension thereof gradually increases from the tip of the free end  86  to the hook-like portions  85 . The transition from the free end to the hook-like portions may be a rectilinear transition, an arcuate transition or other curved transitions, preferably a smooth transition. 
         [0103]    Referring to  FIG. 19 , the hook-like second holding member  82  has a cross section of an arm extending curvedly downwardly. This structure itself enables the second holding member  82  to have an elastically deforming capability. When the free end  86  with a substantially tapered surface shown in  FIGS. 16-18  contacts with the second holding members  82 , the free end can easily enable the second holding members  82  to deform elastically and pass over the second holding members  82 . When the free end  86  passes over the second holding members  82 , the second holding members  82  elastically return. At this time, if the first holding member  81  intends to retreat, the second holding members  82  will be snap-fitted with the hook-like portions  85  of the first holding member  81 , thereby preventing the retreat of the first holding member  81 . That is, the hook-like portions of the first holding member  81  are engaged with the second holding members  82  in an unretreatable manner. 
         [0104]    In a further preferred embodiment (not shown), a hook-like portion is additionally formed on one widthwise surface  84  of the free end  86  of the first holding member  81  and configured the same as the above-mentioned hook-like portions  85 . Correspondingly, a second holding member the same as the above-mentioned holding members  82  may be formed on the connecting portion. When the protection arm  6  rotates to the full protection position, the three hook-like portions  85  of the first holding member  81  are respectively engaged with three second holding members  82  in an unretreatable manner. 
         [0105]    In a still further preferred embodiment (not shown), no second holding members may be provided on the positioning arms. The above-mentioned second holding member  82  may be only formed on the connecting portion  2 . In such a case, the first holding member  81  may be only formed with one hook-like portion  85  corresponding to the second holding member  82  so that when the protection arm  6  rotates to the full protection position, the hook-like portion  85  of the first holding member  81  is engaged with the second holding member  82  in an unretreatable manner. 
         [0106]    Although the present invention has been particularly described with reference to the accompany drawings in the above, it should be understood by those skilled in the art that the above particular descriptions are only exemplary and for illustrative purpose, but not to limit the protective scope of the present invention which is only defined by the appended claims. In light of the teaching of the present invention, those skilled in the art may make various modifications, changes or substitutions under particular circumstances which fall within the protective scope of the present invention.