Abstract:
This device comprises:
       a body housing a hollow injection needle and a container containing the injectable product; the needle is connected to the body but able to move relative to the latter between an injection position and a retracted position;   a plunger that slides in the body and is displaceable relative to the latter to perform the injection; the container is able to move relative to the plunger between a position that enables the injection to be performed and a retracted position;   an arrangement for keeping the needle and the plunger in injection position, which arrangement can be released to free the needle and the plunger to move to the retracted position.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to a device for injecting a product, particularly for medical use. This device is particularly designed for performing an intradermal injection. 
   In the following description, the terms “proximal” and “distal” are considered with reference to the direction in which the product is injected. 
   DESCRIPTION OF THE PRIOR ART 
   Intradermal injections are often performed with conventional syringes, the needle being inserted at a direction forming a slight angle with the skin. 
   These conventional syringes do not inject completely reliably, nor are they totally proof against the risk of accidental stabs which can occur after the injection. 
   The invention seeks to overcome this fundamental problem. 
   The object of the invention is therefore to provide a device that injects with complete reliability and is totally proof against the risk of accidental stabbing. 
   SUMMARY OF THE INVENTION 
   This object is achieved with a device comprising:
         a body housing an injection needle and a container containing the injectable product; the needle is connected to the body but able to move relative to the latter between an injection position and a retracted position;   a plunger that slides in the body and is displaceable relative to the latter to perform the injection; said container is closed at one end and is connected to this plunger but is able to move relative to the latter between a position that enables the injection to be performed and a retracted position;   means for keeping the needle in position, which means normally keep the needle in the injection position and can be released to free the needle to move to said retracted position;   means for keeping the container in position, which means normally keep the container in the position that enables the injection to be performed, and can be released to free the container to move to said retracted position;   a piston engaged in the container and so shaped that, in a first configuration of the piston or relative position of this piston and of this container, it closes the container in such a way as to isolate the product from the environment outside this container and, in a second configuration of the piston or relative position of this piston and of this container, it allows the product to pass out of the container, and   respective means for operating said means of holding the needle in position and said means of holding the container in position, which, at the end of the injection, release the means of holding the needle in position before, or at the same time as, said means of holding the container in position are released.       

   While the injection is being performed, the needle is kept in the injection position relative to the body and the container is kept in the injection position relative to the plunger. The movement of the plunger relative to the body whereby the closed end of the container is moved toward the needle moves the piston into said second configuration or position, allowing the product to pass out of the container. 
   At the end of the injection, the respective operating means release said means of keeping the needle in position and said means of keeping the container in position. This allows the needle and container to be moved into the retracted position. This retraction makes the device totally proof against the risk of accidental stabbing. 
   The piston may be so shaped that, in said second configuration or position, it allows the product to pass between itself and the container. The piston may in particular comprise at least one peripheral zone that is able, in said first configuration of the piston, to press tightly against the wall of the container, and, in said second configuration of the piston, to withdraw under the pressure of the injectable product to allow the latter to pass it. 
   The piston may also comprise a pierceable zone located in line with the proximal end of the needle. The movement of the container relative to the needle thus causes the proximal end of the needle to pierce this pierceable zone of the piston so that it comes into communication with the injectable product and allows this product to flow out through the needle. 
   Advantageously, the device comprises spring means for moving the needle and the container to the retracted position without voluntary external action. 
   Advantageously, said body forms a distal wall perpendicular to the axis of the needle, from which the needle projects, in the injection position, to a distance equal to the desired depth of insertion of this needle during the injection. 
   This distal wall forms a stop wall designed to be pressed against the skin when the needle is inserted in order to limit its insertion to said desired depth. 
   The device according to the invention is thus particularly suitable for performing intradermal injections. 
   In the retracted position, the needle can be simply retracted behind this wall, in the proximal direction, to eliminate the risk of accidental stabbing after injection. 
   In one possible embodiment of the invention, said means of holding the needle in position comprise:
         a needle-supporting part comprising at least one locking means; and   at least one tab that comprises a locking means able to engage with that of said needle-supporting part, this tab being moveable radially between a normal, radially inward position, in which said locking means engage with each other to keep said needle-supporting part in position relative to said body, and a radially outward position, in which a zone of the plunger moves this tab radially out to unlock it, thereby freeing said needle-supporting part from said body.       

   In one possible embodiment of the invention, said means of keeping the container in position comprise:
         a flange formed at the opposite end of the container from the closed end of this container;   engagement means integral with said plunger for connecting said flange to the plunger; and   at least one tab comprising said engagement means and able to move in the radial direction of this plunger between a radially inward position, in which said engagement means connect said flange to the plunger, and a radially outward position, in which said engagement means are withdrawn radially wide of this flange, thereby releasing it.       

   The accompanying figures illustrate, by way of example, a preferred embodiment of the device according to the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of the invention; 
       FIG. 2  is an exploded perspective view of the same, in a cross section passing along its axis; 
       FIG. 3  is a perspective view of the same, in cross section passing along its axis, in the assembled condition; 
       FIG. 4  is a partial view, on a larger scale, of its distal end, in cross section on a plane perpendicular to the cutting plane of  FIGS. 2 and 3 , with the needle kept in position by means belonging to this device; 
       FIG. 5  is a view of the device similar to  FIG. 4 , in a relaxed position of these means of keeping the needle in position; 
       FIGS. 6-8  are partial views of the same, on a larger scale, in a cross section passing along its axis, respectively showing the storage position, the injection position and the end-of-injection position, and 
       FIG. 9  shows, on an enlarged scale, a cap belonging to the device. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The figures show a device  1  for injecting a product, particularly for medical use. 
   As is visible more particularly in  FIG. 2 , the device  1  comprises a body  2 , a protective distal cap  3 , a hollow injection needle  4 , needle  4  assembly parts  5  to  7 , a spring  8 , a plunger  9 , a container  10  and a piston  11 , all described in detail below. 
   The body  2  is of a generally tubular shape and comprises a circular rib  15  near its distal end. 
   The cap  3  has wings  20  for holding it by and can be clipped onto a boss  21  formed by one of the needle  4  assembly parts  6  (needle-supporting part  6 ). As  FIG. 9  shows, this cap  3  may include at least one opening for air to escape through when a portion  26  of the part  6  is inserted into the container  10 , as will be seen later. In the embodiment shown in this  FIG. 9 , the cap  3  has several interrupted ribs  3   a , tiered in the axial direction, with interruptions which are staggered angularly to form a maze. 
   The needle  4  is fixed to the part  5 . The latter is generally cylindrical in shape and has a groove and a hole which form a flow channel communicating with the cavity inside the needle  4 . 
   The part  6  has a tube-shape proximal portion  26  in which the part  5  is tightly housed, and comprises a distal hole to allow the needle  4  to be inserted through the boss  21 . The portion  26  is designed to be inserted into the container  10 , as mentioned earlier, and comprises a seal  25  near its proximal end. This portion  26  thus makes it possible to move the piston  11  inside the container  10  when the plunger  9  is moved relative to the body  2 , as will be seen later. 
   The part  6  also includes a secondary flange  27  designed to clip into openings  28  (more particularly visible in  FIG. 4 ) in two secondary tabs  29  belonging to the part  7 . These tabs can move radially relative to the latter. 
   The part  7  is designed to fit tightly into the opening defined by the distal rib  15  of the body  2 , while a distal flange  30  on the part  7  sits in the distal recess defined by this rib  15 . This tight engagement secures the part  7  to the body  2 . 
   The part  7  also includes an opening through which the boss  21  can pass so that the cap  3  can be placed on this boss. This opening is defined by a lip  31 , the diameter of which is less than the diameter of the spring  8 . 
   As shown in  FIG. 4 , this lip  31  keeps the spring  8  compressed between the proximal face of this lip  31  and the distal face of the flange  27  when the part  6  is clipped onto the part  7 . 
   The part  7  also has walls  32  between the tabs  29 . As can be seen in  FIGS. 3 and 4 , the tabs  29  have internal inclined ramps formed on their proximal ends while the walls  32  have external inclined ramps formed on their proximal ends. 
   The plunger  9  is engaged in the body  2  and can slide relative to the latter. It comprises lateral ribs  35  for guiding the sides of the container  10 . 
   At its distal end, the plunger  9  forms two radially moveable tabs  39  with internal projections  41  forming stops for receiving a flange  45  on the container  10 . When the flange  45  meets the projections  41 , the flange  45  becomes connected to the plunger  9  in the direction in which the plunger  9  moves when performing the injection. 
   The plunger  9  also forms two walls  42  situated between the tabs  39 . As can be seen in  FIGS. 3 and 4 , the tabs  39  comprise, at their distal ends, internal inclined ramps designed to interact with the ramps of the walls  32  at the end of the injection stroke, and the walls  42  comprise, at their distal ends, external inclined ramps designed to interact with the internal ramps on the tabs  29 , likewise at the end of the injection stroke. 
   At the opposite end from the flange  45 , the container  10  comprises a bottom  46 . The injectable product is contained between the piston  11  and the walls of the container  10 . 
   The piston  11  is made of a flexible material, especially an elastomer. It is of conical shape and is placed inside the container  10  so that its face having a smaller surface area is turned toward the injectable product. In this way, as  FIG. 6  shows, it forms a gap  50  between itself and the wall of the container  10 . The piston  11  also includes a lateral blind hole  51  running most of the way through its thickness, from its distal axial face, next to the side wall of the piston  11  defining said gap  50 . The hole  51  is shaped so that it follows this side wall, at least approximately, and thus defines a peripheral zone occupying a portion of the periphery of the piston  11 . 
   As a comparison of  FIGS. 6 and 7  will show, this peripheral zone normally adopts a radially outward position shown in  FIG. 6 , in which it presses tightly against the wall of the container  10 , and can adopt a radially inward position shown in  FIG. 7 , into which it withdraws under the pressure of the injectable product as the latter passes between the piston  11  and the container  10 , due to the pressure of the piston  11  on the product, without the needle  4  piercing the piston  11 . In the position shown in  FIG. 7 , the piston  11  is spaced from, and not in contiguous contact with, the needle  4 . 
   In practice, the device  1  is initially in the storage position shown in  FIG. 6 , in which the flange  27  is in engagement with the tabs  29  and the flange  45  is kept in position by the projections  41 . In this position the needle  4  projects beyond the distal end of the device to the desired depth for injection, which is an intradermal injection in the example illustrated. 
   The movement of the container  10  with the plunger  9  presses the piston  11  against the injectable product, which causes the product to flow between the piston  11  and the container  10 , as appears in  FIG. 7 . The injection is then performed by continuing the movement of the plunger  9  relative to the body  2 . 
   As the plunger reaches the end of the injection stroke, the ramps of the tabs  39  and of the walls  42  bear against the ramps of the walls  32  and of the tabs  29 , respectively, with the result that the tabs  29  and  39  are displaced toward radially outward positions in which they free the flanges  27  and  45 , respectively. The spring  8  can now relax, which causes a simultaneous retraction of the parts  5  and  6 , and therefore of the needle  4 , as well as of the container  10  owing to the friction of the seal  25 , into a retracted position shown in  FIG. 8 . In this position the distal end of the needle  4  is behind the distal face of the part  7  and the flange  45  is behind the projections  41 , on the proximal side. 
   It can be seen from the above that the invention makes a number of crucial improvements to the corresponding devices of the prior art, by making it totally proof against the risk of accidental stabbing which can occur after the injection. 
   It goes without saying that the invention is not limited to the embodiment described above by way of example, but that on the contrary it encompasses all alternative embodiments that come within the scope of protection defined by the claims appended hereto. In particular, the piston may comprise a pierceable zone located in line with the proximal end of the needle, this proximal end projecting from the proximal end of the part  5  in which it is held.