Abstract:
A needle-protection device ( 2 ) for a syringe ( 1 ) having a needle ( 6 ), a tubular body ( 4 ) and an injection plunger ( 8 ). The device includes: a needle protector ( 22 ); a protector support ( 20 ); a spring ( 24 ) which presses against the support ( 20 ) and the protector ( 22 ), the support and protector being movable relative to one another between a retracted protector position, in which the needle of the syringe is exposed and the spring is locked in compression, and a deployed protector position in which the needle is disposed inside the protector and the spring is at least partially decompressed; and a mechanism for unlocking the spring. When locked, the spring ( 24 ) exhibits a predetermined force which is greater than the push force required to move the plunger ( 8 ) along essentially all of the injection stroke thereof. The mechanism has a digital support flange ( 50 ) which (i) transmits to the spring a compression force, which is less than the predetermined force, as the plunger slides along the injection stroke, and (ii) transmits to the spring a compression force, which is greater than the predetermined force, when the plunger reaches the end of the injection stroke.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a needle protection device for a syringe which comprises a needle, a tubular body, to the distal end of which the needle is fixed, and an injection piston which is slidingly arranged in the body, this device comprising a needle protector which is substantially coaxial with the body of the syringe; a protector support which is fixedly joined to the body or which is provided with means for being fixedly joined to the body; a spring which is arranged between and in contact with the support and the protector, the support and the protector being movable relative to each other between a retracted position of the protector, in which the needle of the syringe is disengaged and the spring is locked in a compressed state, and a deployed position of the protector, in which the needle is arranged inside the protector and the spring is, at least partially, relaxed; and means for unlocking the spring. 
     The invention relates in particular to the field of single-use pre-filled injection syringes which are intended in particular for intramuscular or subcutaneous injections. 
     These devices are intended to limit to the greatest possible extent the risk, to the user, of accidental pricks after the injection since, once the contents of the syringe have been injected, the needle of the syringe is withdrawn from the patient and the protector is brought into the deployed position all around the needle. 
     In order to ensure a higher level of safety of use, it has been proposed to provide these devices with resilient means for displacing the protector around the needle of the syringe. In this manner, document U.S. Pat. No. 5,591,138 describes a device of the above-mentioned type which can be used in one of the two following manners: once the injection has been carried out with one hand, the user operates the unlocking means with his other hand in order to disengage the compression spring and to allow the deployment of the protector around the needle. Alternatively, the needle is introduced to a sufficient depth into the skin of the patient to bring about the unlocking of the spring, the spring not being able in any case to relax owing to the protector being pressed against the skin of the patient; in this case, the spring relaxes when the assembly of the device is moved away from the patient. 
     Therefore, this type of device requires, in order to achieve the desired deployment of the protector, either manipulation with two hands or the protector to be pressed against the skin of the patient. This manipulation ensures neither a high level of ease of use for the practitioner, nor great comfort for the patient. Therefore, these devices remain little used because their use is too far removed from the conventional use of an injection syringe. Furthermore, once the spring is unlocked, the decompression energy of the spring is often violently released without any control by the user being possible, which brings about a degree of instability of the device in the hand of the user. Furthermore, the rigid locking of the protector in the deployed position, in particular in order to prevent any re-use of the device, is possible only by the device being manipulated with two hands. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a protection device which allows the protector to be deployed with the same hand as that which holds the syringe, with a simple releasing action without the protector needing to be pressed against the patient, and control of the displacement of the protector by the user being possible. 
     To this end, the invention relates to a protection device of the above-defined type for which the spring has, in the locked state, a predetermined force which is greater than the pushing effort necessary for displacing the syringe piston over substantially the entire injection path, and the unlocking means comprise a finger support flange which is fixedly joined to the protector and which is suitable for, on the one hand, transmitting to the spring a compression force less than that predetermined force when the piston slides for the injection and, on the other hand, transmitting to the spring a compression force greater than that predetermined force when the piston is at the end of the injection path. 
     According to other features of this device, taken in isolation or according to all technically possible combinations:
         the pushing effort is at least equal to the sum of the injection effort and the efforts for detaching and sliding the piston inside the body of the syringe;   the flange is located at the proximal end of the protector;   the length of the protector is substantially equal to that of the body of the syringe;   for a syringe whose body is integrally provided with a neck at the proximal end thereof, the means for fixedly joining the protector support to the body of the syringe comprise means for fixing the support to the neck of the syringe,   the fixing means comprise at least one clip-fit hook for the neck of the syringe;   the support and the protector are arranged for rotation relative to each other between the retracted position of the protector and a position for unlocking the spring;   the unlocking means comprise, on the one hand, at least a first groove which is arranged in one of the support or the protector, and which is at least partially inclined relative to the axial direction of the body of the syringe and, on the other hand, at least one pin which is fixedly joined to the other of the support or the protector and which is received in that first groove, the groove and the pin co-operating in order to guide in rotation the support and the protector relative to each other between the retracted position of the protector and the position for unlocking the spring;   at least a second groove for receiving the pin, which groove communicates with the first groove, is arranged in the one of the support or the protector in which the first groove is arranged, the second groove extending substantially in the axial direction of the body of the syringe so as to be able to guide the support and the protector in translation relative to each other between the position for unlocking the spring and the deployed position of the protector;   the distal base of the second groove forms an axial locking stop in the direction of deployment of the protector for the associated pin;   it comprises means for locking the protector in the deployed position;   those locking means comprise, on the one hand, at least one tongue which is fixedly joined to the support and, on the other hand, at least one deformable hook which is fixedly joined to the protector, each tongue and each hook respectively having two substantially conjugate contact surfaces which are suitable for radially deforming the corresponding hook when the support and the protector move from the retracted position to the deployed position of the protector, and each tongue and each hook respectively have two substantially conjugate axial stop surfaces which are suitable for locking the support and the protector relative to each other in the deployed position of the protector;   it comprises means for controlling the first use of the device; and   those control means comprise, on the one hand, a detachable cap for being arranged around the needle of the syringe before use and, on the other hand, deformable tongues which are arranged at the distal end of the protector and which delimit a passage opening, the diameter of which is, when the tongues are not deformed, less than the maximum diameter of the cap.       

     The invention further relates to an injection device comprising, on the one hand, a syringe which comprises a needle, a tubular body, to the distal end of which the needle is fixed, and an injection piston which is slidingly arranged in the body and, on the other hand, a needle protection device which simultaneously comprises a needle protector which is substantially coaxial with the body of the syringe, a protector support which is fixedly joined to the body or which is provided with means for being fixedly joined to the body of the syringe, a spring which is arranged between and in contact with the support and the protector, the support and the protector being movable relative to each other between a retracted position of the protector, in which the needle of the syringe is disengaged and the spring is locked in a compressed state, and a deployed position, in which the needle is arranged inside the protector and the spring is, at least partially, relaxed, and means for unlocking the spring, wherein the needle protection device is as defined above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood from a reading of the description below which is given purely by way of example and with reference to the drawings, in which: 
         FIG. 1  is an exploded perspective view of an injection device according to the invention before assembly; 
         FIG. 2  is a front view of the protection device belonging to the injection device of  FIG. 1  in the retracted position; 
         FIG. 3  is a sectioned view in plane III-III indicated in  FIG. 2 ; 
         FIG. 4  is a top view according to arrow IV indicated in  FIG. 2 ; 
         FIG. 5  is a sectioned view in the plane designated V-V in  FIG. 4 ; 
         FIG. 6A  is a view, in the same plane of section as that of  FIG. 5 , of the injection device according to the invention before use; 
         FIG. 6B  is a top view according to arrow VI indicated in  FIG. 6A ; 
         FIG. 7  is a view similar to that of  FIG. 6A , the injection device being in use; 
         FIG. 8  is a view, in the same plane of section as that of  FIG. 3 , of the injection device after use; 
         FIG. 9  is a view identical to that of  FIG. 8 , the syringe of the injection device not being illustrated; 
         FIG. 10  is a sectioned view in plane X-X indicated in  FIG. 8 ; and 
         FIGS. 11 to 13  illustrate the injection device in the deployed position,  FIG. 11  being a view similar to that of  FIG. 8 ,  FIG. 12  being a sectioned view in plane XII-XII indicated in  FIG. 11  and  FIG. 13  being a view identical to that of  FIG. 11 , the syringe not being illustrated. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a perspective view of a syringe  1  and a protection assembly  2 . Hereinafter, the terms “proximal” and “rear” are synonyms, as are the terms “distal” and “front”. 
     The syringe  1  is a glass syringe of standard type, which is intended for single use. It contains a liquid to be injected into a patient in an intramuscular or subcutaneous manner. For this purpose, it comprises a body  4 , a needle  6  which is fixedly joined to the distal end of the body  4  and a piston  8 . This piston conventionally comprises a rod  10  which is provided, at the distal end thereof, with a push-button  12 , which is not visible in  FIG. 1 , and a contact head  14 , on which the thumb of the hand of the practitioner is intended to press. 
     The body  4  of the syringe comprises, in the proximal portion thereof, a neck  16  which circumferentially delimits two diametrically opposed lugs  18  which are generally intended, in particular in the absence of the assembly  2 , to form contact surfaces for the index finger and second finger of the practitioner during the manipulation of the syringe and the injection of the liquid therein. 
     The protection assembly  2  generally having an axis X-X substantially comprises, as illustrated in  FIG. 1 :
         a support  20  of generally tubular shape;   a protective sleeve  22  which is arranged coaxially relative to the support  20  and which has a diameter greater than that of the support, and   a spring  24 .       

     These three elements will be described in detail in succession below with reference to  FIGS. 2 to 4 . 
     The support  20  comprises a main portion  26  which is substantially cylindrical and which has an inside diameter substantially equal to the outside diameter of the body  4  of the syringe  1 . This portion  26  continues at the proximal end thereof with a secondary portion  28  having larger inside and outside diameters than those of the main portion  26 , a radial shoulder  29  being formed. 
     The proximal portion  28  is provided with means  30  for fixing to the syringe neck  16 . In greater detail, these means  30  comprise, on the one hand, a pair of diametrically opposed deformable hooks  32  which are also visible in  FIG. 1 . Each of these hooks has a substantially frustoconical inclined surface  32 A which widens towards the free end of the portion  28  and which is intended to be resiliently repelled by the lugs  18  of the syringe neck  16  when the support  20  is fixed to the syringe  1 . The hooks  32  are remote from the shoulder  29  by a distance substantially equal to the thickness of the lugs  18 . The hooks  32  thus form a clip-fit means for the syringe neck  16 . 
     The fixing means  30  comprise, on the other hand, protrusions  34  ( FIGS. 1 ,  4  and  6 B) which project radially towards the interior of the portion  28 . These protrusions are suitable for forming, on the one hand, angular indexing means, at approximately 180°, of the neck  16  of the syringe and, on the other hand, rotation locking stops for the neck  16  when the neck  16  is axially retained between the hooks  32  and the shoulder  29 . 
     Two traversing grooves  36  are arranged facing each other in the main portion  26 . Each groove is constituted by a first rectilinear portion  38 , which extends substantially along axis X-X of the support  20  over a length greater than that of the needle  6 , and a second rectilinear portion  40  which extends in an inclined manner relative to the same axis X-X. The inclined portion  40  opens at the proximal end portion of the main groove portion  38  and forms a V-shape, the point of which is directed towards the proximal side of the assembly  2 . 
     The main portion  24  comprises, at the distal end thereof, a first pair of diametrically opposed tongues  42  which are each located in the continuation of the grooves  36  ( FIG. 5 ). These tongues  42  have an inner face  42 A of substantially cylindrical shape and a substantially frustoconical outer face  42 B which is divergent towards the rear. 
     The main portion  24  comprises a second pair of diametrically opposed tongues  44  which are located between the tongues  42  along the circumference of the distal end of this portion. They have a substantially frustoconical outer surface  44 A, which is divergent towards the front, and a substantially planar distal surface  44 B. 
     Plumb with these tongues  44  at the proximal end, longitudinal recesses  26 A are arranged in the main portion  26  ( FIG. 3 ). 
     In addition, at one side and the other of the tongues  42 , axial slots  26 B are provided starting from the distal end of the support in such a manner that, before the body  4  of the syringe  1  is inserted inside the support  20 , these tongues  42  can be deformed radially, in particular inwards. 
     The protective sleeve  22  has a length substantially equal to that of the body  4  of the syringe  1 . It is constituted by two cylindrical portions  46  and  48 , the proximal portion  46  having a diameter slightly greater than that of the main portion  48 . These two portions fit together to form a radial shoulder  49 . 
     The sleeve  22  integrally comprises, in the proximal portion thereof, an external flange  50  in the form of two diametrically opposed lugs  52  ( FIG. 4 ). 
     Two diametrically opposed studs  54  are fixedly joined to the sleeve ( FIG. 5 ) also in the proximal portion of, but inside, the protective sleeve  22 . These two studs are suitable for being received and guided in the two respective grooves  36  of the support  20 , the support and the sleeve thus being movable relative to each other in translation along the common axis thereof and with limited rotation about the same axis when the pins  54  are located in the groove portions  40 . 
     In greater detail, the support  20  and the sleeve  22  can be moved between a retracted position of the sleeve, in which the greater part of the sleeve covers the greater part of the support and the studs  54  are located at the distal end of each of the inclined groove portions  40 , as illustrated in  FIGS. 2 to 7 , and a deployed position of the sleeve, in which the sleeve projects axially from the support and the studs are located at the distal end of the longitudinal groove portion  38 , as illustrated in  FIGS. 11 to 13 . 
     When the syringe  1  is fixed to the assembly  2 , these extreme positions correspond to an injection configuration, in which the needle  6  of the syringe  1  is disengaged and intended to be inserted into a patient, and a protection configuration, in which this needle is surrounded by the protective sleeve  22 , respectively. 
     The proximal portion of the sleeve  22  further comprises internally a pair of diametrically opposed deformable hooks  56 . Each of these hooks has, on the one hand, an inner surface  56 A of substantially frustoconical shape which is divergent towards the front and which is complementary to that of the inner surfaces  44 A of the tongues  44  of the support  20 , and a proximal surface  56 B which is substantially planar ( FIG. 3 ). 
     In the retracted position of the sleeve, those hooks  56  extend inside the recesses  26 A which are arranged in the support  20 . In the deployed position of the sleeve, as illustrated in  FIG. 11 , the faces  56 B of the hooks  56  are stopped axially against the tongues  44 , the hooks and tongues in this manner forming a rigidly locking assembly in the deployed position. 
     The sleeve  22  is further provided at the distal end thereof with a crown of deformable tongues  58 , the distal edges of which form a substantially circular opening  60  having a diameter less than the inside diameter of the main portion  26  of the support  20 . 
     The spring  24  is a helical spring which is arranged between the protective sleeve  22  and the protector support  20 . In greater detail, the spring is received between the shoulder  29  of the support  20  and the shoulder  49  of the sleeve  22 . In the retracted position of the sleeve, the spring  24  is in a compressed state, thus having decompression energy linked to the tension of the spring and the difference between the length of the spring in the rest state and its length, designated L in  FIGS. 2 to 7 , in the compressed state. That is to say that the spring  24  has a predetermined supplementary compression force threshold which corresponds to the minimum force necessary to further compress the spring from the initial compressed state thereof of  FIGS. 2 to 7 . The tension of the spring and/or initial compression length L are selected so that this predetermined force threshold is greater than the pushing effort necessary to displace the piston  8  of the syringe  1  over the entire injection path thereof. In greater detail, the predetermined force of the spring in the locked state is greater than the sum of the injection effort, that is to say, the effort for evacuating the liquid out of the needle  6  of the syringe  1 , and the efforts for detaching and sliding the push-button  12  inside the body  4  of the syringe. 
     Optionally, the protection assembly  2  further comprises a cap  66  of generally tubular shape illustrated in  FIGS. 1 and 6A . 
     The cap  66  is suitable for surrounding the needle  6  before the syringe  1  is used. This cap is closed at one of the ends thereof and the opposite end thereof is formed by an annular ring  68  having an outside diameter suitable both for being conjugate with the surface  42 A of the hooks  42  of the support  20  and for being greater than the diameter of the opening  60  formed by the tongues  58  of the protective sleeve  22 . The inner face of this ring  68  is intended to be adhesively bonded to the glass base  67  of the syringe body  4 , where the needle  6  is fixed, in particular to ensure given sealing with respect to bacteria. 
     The operation of the injection device according to the invention is as follows: 
     Firstly, the protection device  2  is assembled in the retracted configuration, that is to say, that of  FIGS. 2 to 7 . The protective sleeve  22  is fitted around the support  20  for this purpose, starting from the distal end of the support, with the spring  24  being arranged between them. In greater detail, the sleeve is displaced axially backwards relative to the support, whilst at the same time radially deforming the hooks  56  outwards by means of a suitable tool, at least until the hooks  56  axially reach the front portion of the longitudinal recesses  26 A. With the sleeve still being displaced backwards, the pins  54  are then pressed against the outer surfaces  42 B of the tongues  42 , with the tongues  42  being deformed inwards, until the pins are received in the groove portions  38 . The displacement of the protector  22  backwards then continues until the pins  54  are received in the inclined groove portions  40 , the support and the protector being pivoted relative to each other. The protector is thereby located in the retracted position. 
     Secondly, the glass syringe  1  is pre-filled with a liquid to be injected into a patient. This syringe is provided with the cap  66  which encloses the base  67  of the syringe body  4 . 
     The syringe and the cap are then inserted inside the assembly  2  in order to form the injection device, as illustrated in  FIGS. 6A and 6B . In greater detail, the body  4  of the syringe is displaced substantially axially inside the support  20  until the syringe neck  16 , which is indexed by the protrusions  34 , clips inside the proximal portion  28 , the hooks  32  being deformed radially outwards. The lugs  18  of the syringe neck  16  are then retained axially by the hooks  32 , whilst the peripheral protrusions  34  retain the syringe neck, and therefore the syringe, in terms of rotation with respect to the support  20 . 
     Furthermore, insofar as the syringe neck  16  is completely clipped inside the portion  28 , it can no longer serve as usual to form a contact surface for the index finger and the second finger  9  of the practitioner. This support function is fulfilled by the flange  50  which is fixedly joined to the sleeve  22 . Insofar as the length of the protective sleeve  22  is substantially equal to that of the syringe body  4  and/or the flange  50  is arranged in the region of the proximal end of this sleeve, the practitioner can manipulate the syringe by resting his thumb on the contact head  14  of the piston  8  as in the accustomed manner, and by resting his index finger and second finger on the faces of the lugs  52  that are directed towards the needle  6 . 
     Furthermore, when the syringe  1  is fixed to the protector support  20 , as illustrated in  FIGS. 6A and 6B , the cap  66  projects outside the protective sleeve  22 . 
     When the practitioner is ready to carry out the injection of the liquid contained in the syringe, he retracts the cap  66  by drawing it axially forwards. The ring  68  then passes through the opening  60 , deforming the tongues  58 . Once the cap  66  has been retracted, the tongues  58  again take up the initial position thereof. The passage hole  60  at the distal end of the sleeve, having a diameter smaller than the outside diameter of the cap  68 , then prevents the cap from being repositioned around the needle. The co-operation of the cap  66  and the tongues  58  thus forms a control means for the first use of the injection device. 
     The practitioner then inserts the needle  6  into a patient. He injects the liquid contained in the syringe by applying a pushing action to the contact head  14  of the piston  8 , his index finger and second finger remaining in contact with the faces of the lugs  52  that are directed towards the needle. During the injection, no movement is brought about between the protector support  20  and the protective sleeve  22 , the spring  24  remaining compressed with a length L, as illustrated in  FIG. 7 . 
     The injection continues until the push-button  12  of the piston  8  reaches the end of the injection path. 
     The practitioner then withdraws the needle from the patient. In order to release the protection assembly  2 , the practitioner applies an additional pressure to the piston rod  8 . This pressure must be greater than the predetermined force produced by the spring  24  in the locked state, so that this spring is further compressed and changes from the length L thereof to a smaller length L′, as illustrated in  FIGS. 8 to 10 . To this end, considering the syringe support to be stationary, the protective sleeve  24  is displaced axially towards the proximal end of the support  20 . The practitioner brings about this movement by applying a corresponding pressure by means of his index finger and his second finger to the lugs  52  of the flange  50  of the sleeve  22 . This pressure brings about, in a manner combined with the translation movement, the rotation of the protective sleeve  22  about the syringe support  20 , the studs  54  being guided by the inclined groove portions  40 . This rotation movement continues until the studs reach the proximal end of this groove portion  40 , that is to say, the proximal end of the longitudinal groove portion  38 , as can be seen in  FIG. 9 . The device  2  is then in the unlocking position of the spring  24 . 
     The practitioner then releases the pressure which he had been applying to the flange  50  until then, allowing the spring  24  to relax as far as a rest state. The pins  54  move in translation inside the longitudinal groove portion  38  as far as the distal end thereof, as illustrated in  FIG. 13 . The translation movement of the sleeve  22  relative to the support  20  can be controlled by the practitioner if he progressively releases the finger-hold which he applies to the flange  50 . When the pins  54  have arrived at the distal end of the groove  36  ( FIG. 13 ), the protector is in the deployed position thereof. 
     Furthermore, when the sleeve  22  is moving in translation relative to the support  20 , the hooks  56  make use of the longitudinal recesses  26 A of the support until they slide along the distal tongues  44  of the support  22  by co-operation between the complementary surfaces  56 A and  44 A thereof. 
     In the deployed position of the protector, the tongues  44  retain the hooks  56  in position by co-operation between the surfaces  56 B and  44 B so that the protective sleeve  22  cannot be moved into the initial position thereof. Similarly, the sleeve  44  cannot readily be detached from the support  20  because the pins  54  are stopped against the distal base of the longitudinal groove portion  38  ( FIG. 13 ), the tongues  42  forming this base being radially retained between the body of the syringe  1  and the sleeve  22 . 
     The injection device according to the invention is simple to use in this manner, whilst at the same time allowing the practitioner to control the movement for covering the needle with the protective sleeve. The number of components constituting the protection assembly  2  illustrated is reduced to three. 
     The device according to the invention can be adapted to various types of syringe, both in terms of the shapes and the volumes thereof. Therefore, this device has the advantage of not calling into question the general shape of the syringes used and consequently does not bring about any modification of the industrial methods for filling these syringes. 
     Various variants of the device according to the invention can be envisaged:
         unlike the embodiment described above, the pins  54  and/or the flange  50  of the protective sleeve  22  can be separate from the sleeve  22  and not produced integrally therewith;   contrary to the device described, the studs  54  can be produced on the outer surface of the protector support  20  and the guiding groove  36  arranged in the protective sleeve  22 ;   the support  20  can be produced in one piece with the syringe body  4 ; and/or   the protrusions  34  of the means  30  for fixing the support  20  to the syringe neck  16  can be dispensed with and optionally replaced with one or more hooks which are similar to the hooks  32  described above, the assembly of these hooks axially retaining the neck  16  relative to the support  20  for any relative angular position between the syringe  1  and the support; in this case, the syringe  1  is free to rotate inside the support  20  which, on the other hand, ensures greater ease of fixing the protection assembly  2  to the syringe (absence of indexing).