Patent Publication Number: US-8968246-B2

Title: Syringe adapter

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. National Phase under 35. U.S.C. §371 of International Application PCT/JP2010/054522, filed Mar. 17, 2010, which claims priority to Japanese Patent Application No. 2009-065888, filed Mar. 18, 2009 and Application No. 2009-191130, filed Aug. 20, 2009. The International Application was published under PCT Article 21(2) in a language other than English. 
     TECHNICAL FIELD 
     The present invention relates to a syringe adapter removably mounted on a chemical liquid injector for injecting a chemical liquid filled in a syringe into a patient in order to allow the chemical liquid injector to hold the syringe. 
     BACKGROUND ART 
     Currently employed medical imaging diagnostic apparatuses include CT (Computed Tomography) scanners, MRI (Magnetic Resonance Imaging) apparatuses, PET (Positron Emission Tomography) apparatuses, angiography apparatuses, MRA (MR Angiography) apparatuses and the like. For obtaining CT images of a patient with the abovementioned apparatuses, a chemical liquid such as a contrast medium or physiological saline is often injected into the patient&#39;s body. 
     In general, the injection of the chemical liquid into the patient is automatically performed by using a chemical liquid injector. The chemical liquid injector has an injection head on which a syringe filled with the chemical liquid is removably mounted and an injection control unit which controls the operation of the injection head. The syringe has a cylinder and a piston inserted thereinto to be movable in its axis direction. The chemical liquid is filled in the cylinder. The injection head includes a piston driving mechanism for pushing the piston of the syringe mounted on the injection head into the cylinder. After an injection needle is connected to the end of the cylinder through an extension tube and is inserted into a patient&#39;s blood vessel, the piston driving mechanism pushes the piston into the cylinder, so that the chemical liquid in the cylinder can be injected into the patient. 
     To inject the chemical liquid in the syringe reliably and safely in the abovementioned chemical liquid injector, it is important to allow the injection head to hold the syringe tightly. Patent Document 1 has disclosed a chemical liquid injector in which a pair of holding members is provided for holding a cylinder flange provided integrally with a cylinder of a syringe from both sides of the syringe on the left and right such that the holding member is held at a closed position for holding the syringe or at an opened position for allowing the insertion of the syringe depending on the mounting or demounting operation of the syringe. 
     There are a plurality of types of syringes having different diameters. To allow the mounting of such syringes having different diameters, adapters matching the diameters of syringes are used. In general, the adapter is removably mounted on the chemical liquid injector with a lock mechanism operated manually. 
     PRIOR ART REFERENCE 
     Patent Document 
     
         
         Patent Document 1: Japanese Patent Laid-Open No. 2004-154238 
       
    
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     While the conventional chemical liquid injector described above has the advantage that the mounting and demounting of the syringe is extremely easy, the movement of the holding member from the closed position to the opened position is realized simply by pulling the syringe upward and thus the syringe may be removed unintentionally. In addition, while currently manufactured syringes have cylinder flanges of various shapes, for example depending on manufacturers or capacities, the abovementioned chemical liquid injector can hold only the syringes having cylinder flanges of a shape matching the holding member. Furthermore, when the syringe is mounted on the chemical liquid injector with the adapter interposed between them, the adapter should be mounted on the chemical liquid injector prior to the mounting of the syringe and this manual operation is burdensome. 
     It is an object of the present invention to provide a syringe adapter for allowing the mounting of syringes having cylinder flanges of various shapes on a chemical liquid injector, the syringe adapter enabling a syringe to be easily mounted thereon and demounted therefrom, easily mounted on and demounted from the chemical liquid injector, and capable of reliably holding the syringe mounted thereon without unintentional demounting. 
     Means for Solving the Problems 
     To achieve the abovementioned object, the present invention provides a syringe adapter for removably holding a syringe having a cylinder and a piston, the syringe adapter being mounted removably on an apparatus for operating the syringe, including a flange receiver, a flange lock mechanism, and an adapter lock mechanism. The flange receiver has a structure matching the shape of a cylinder flange formed at a trailing end of the cylinder of the syringe to be held so as to receive the cylinder flange. The flange lock mechanism locks the cylinder flange by rotation of the syringe received in the flange receiver about an axis of the cylinder. The adapter lock mechanism locks the syringe adapter to the apparatus so as not to release lock to the apparatus in the state in which the cylinder flange of the syringe is received in the flange receiver. 
     In the syringe adapter according to the present invention, preferably, the flange receiver has an arc-shaped portion having an inner circumferential surface with a radius of curvature substantially equal to a radius of curvature of an outer circumferential surface of the syringe flange, an arm portion extending from both ends of the arc-shaped portion and provided to be elastically displaceable with respect to the arc-shaped portion, and a grip portion formed on the arm portion, and part of an inner circumferential surface of the grip portion is formed on the extension of an arc shape of the inner circumferential surface of the arc-shaped portion, and the adapter lock mechanism is provided for on an outer surface of the arm portion. In this case, the adapter lock mechanism can have an engagement structure elastically engaging with an adapter receiving portion formed in the apparatus such that the syringe adapter is inserted therein. 
     The present invention also provides an apparatus on which the syringe adapter according to the present invention is removably mountable. The apparatus includes an adapter receiving portion into which the syringe adapter is inserted, and an engagement structure provided for the adapter receiving portion and locking the syringe adapter in cooperation with an adapter lock mechanism of the syringe adapter. 
     Effect of the Invention 
     According to the present invention, the syringes of various shapes can be mounted on the apparatus on which the syringe is removably mounted. In addition, the mounted syringe can be held tightly while the mounting and demounting of the syringe and the mounting and demounting on and from the apparatus are easily performed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  A perspective view showing an example of a chemical liquid injector in which a syringe adapter according to the present invention is used. 
         FIG. 2  A perspective view showing an injection head shown in  FIG. 1  as well as a syringe and a syringe adapter to be mounted thereon. 
         FIG. 3  A perspective view showing the syringe adapter shown in  FIG. 2  viewed from a front side. 
         FIG. 4  A front view of the syringe adapter shown in  FIG. 2 . 
         FIG. 5  A back view of the syringe adapter shown in  FIG. 2 . 
         FIG. 6  A diagram showing a cylinder of the syringe shown in  FIG. 2  viewed from the side of a cylinder flange. 
         FIG. 7A  A diagram for explaining how to mount the syringe on the syringe adapter, showing the syringe inserted in the syringe adapter. 
         FIG. 7B  A diagram for explaining how to mount the syringe on the syringe adapter, showing the syringe held by the syringe adapter. 
         FIG. 8  A plan view near an adapter receiver of a head body shown in  FIG. 2 . 
         FIG. 9  A perspective view showing the adapter receiver shown in  FIG. 2  viewed from the side of a piston driving mechanism. 
         FIG. 10  An enlarged view showing one of arm portions of the syringe adapter shown in  FIG. 2  viewed from the front side. 
         FIG. 11  A perspective view showing the mounted cylinder with the syringe adapter interposed. 
         FIG. 12  A perspective view showing another embodiment of the syringe adapter according to the present invention viewed from the back side. 
         FIG. 13  A back view showing the syringe adapter shown in  FIG. 12  while wall surfaces formed on a base member and a flange lock member are removed. 
     
    
    
     EMBODIMENT FOR CARRYING OUT THE INVENTION 
     Referring to  FIG. 1 , an example of chemical liquid injector  100  which employs a syringe adapter according to the present invention is shown. Chemical liquid injector  100  has injection head  110  and injection control unit  101  which controls the operation of injection head  110 . Injection head  110  is attached to the top end of stand  111  by movable arm  112  and is connected to injection control unit  101  through cable  102 . Injection control unit  101  has main operation panel  103 , touch panel  104  serving as a display device and an input device, hand unit  107  connected thereto through cable  108  and serving as an auxiliary input device, and the like. 
     As shown in  FIG. 2 , injection head  110  is provided for removably mounting two syringes  200 C and  200 P and has two concave portions  114  for supporting these syringes  200 C and  200 P in an upper surface of head body  113 . Each of syringes  200 C and  200 P has cylinder  210  having cylinder flange  211  formed at its trailing end and piston  220  having a piston flange formed at its trailing end. Each of syringes  200 C and  200 P is filled with a chemical liquid. For example, one syringe  200 C can be filled with a contrast medium and the other syringe  200 P can be filled with physiological saline. Each of syringes  200 C and  200 P can be realized by using a syringe of a pre-filled type which is previously filled with a chemical liquid by a manufacturer, or a syringe of a field filling type which is filled with a chemical liquid as required in a medical location or the like. Connection tube  230  joining into one at an intermediate portion and provided with an injection needle at its leading end is connected to the leading ends of two syringes  200 C and  200 P mounted on head body  113 . 
     Syringes  200 C and  200 P are mounted on injection head  110  with syringe adapter  300  interposed between them. Syringe adapter  300  is formed to hold the cylinder flanges of syringes  200 C and  200 P. In part of concave portion  114  of injection head  110 , adapter receiver  114   a  serving as an adapter receiving portion provided to receive syringe adapter  300  is formed to have an opening in an upper portion. Syringe adapter  300  will be described later in detail. 
     Two piston driving mechanisms  130  which are independently driven for operating pistons  220  of mounted syringes  200 C and  200 P are provided for injection head  110  corresponding to the respective concave portions  114 . Piston driving mechanisms  130  operate pistons  220  of mounted syringes  200 C and  200 P to allow the injection of the contrast medium and the physiological saline filled in syringes  200 C and  200 P separately or simultaneously into a patient. Piston driving mechanism  130  can be realized by employing a known mechanism used typically for the injector of this type. 
     Chemical liquid injector  100  is connected to an imaging diagnostic apparatus (not shown) for obtaining diagnostic images of a patient, for example an X-ray CT apparatus. After chemical liquid injector  100  injects the chemical liquid upon the injection conditions specified for the site of imaging, the body conditions of the patient or the like, the diagnostic imaging apparatus can obtain the diagnostic images of the patient. 
     Next, syringe adapter  300  mentioned above will be described in detail with reference to  FIGS. 3 to 5 . In the following description, syringes  200 C and  200 P held by syringe adapter  300  are not identified separately and the simple designation of “syringe  200 ” is used. 
     Cylinder adapter  300  has base member  310  and flange lock member  320  fixed to base member  310  for locking cylinder flange  211 . While base member  310  and flange lock member  320  are formed of different members in the present embodiment, they may be formed integrally as one part. 
     Base member  310  has an inner circumferential surface formed in generally arc shape. The radius of curvature of the inner circumferential surface is set to be smaller than the radius of curvature of an outer circumferential surface of cylinder flange  211  and to avoid interference with piston  220  of syringe  200  when piston  220  is operated. 
     Flange lock member  320  has arc-shaped portion  321  having an inner circumferential surface formed in generally arc shape and is placed over base member  310  such that the radius of curvature of the inner edge is located coaxially with the radius of curvature of the inner edge of base member  310 . While arc-shaped portion  321  is formed entirely in arc shape in the present embodiment, the outer surface of arc-shaped portion  321  may have an arbitrary shape as long as at least the inner circumferential surface is formed in arc shape. 
     Flange lock member  320  further has a pair of arm portions  322  extending in parallel with each other from both ends of arc-shaped portion  321  to form a U shape as a whole. Arm portions  322  are supported to be elastically displaceable with respect to arc-shaped portion  321  so that the interval between arm portions  322  can be changed. Thus, the fixing of base member  310  to flange lock member  320  is performed at arc-shaped portion  321 . 
     Inner circumferential surface  321   a  of arc-shaped portion  321  has the radius of curvature substantially equal to the radius of curvature of the outer circumferential surface of cylinder flange  211  so that the outer circumferential surface of cylinder flange  211  is supported on inner circumferential surface  321   a . The radius of curvature of inner circumferential surface  311  of base member  310  and the radius of curvature of inner circumferential surface  321   a  of flange lock member  320  are defined in this manner in association with the shape of cylinder flange  211  of cylinder  210  to result in a difference in height formed between base member  310  and arc-shaped portion  321  of flange lock member  320 . The surface of base member  310  provided by this difference in height serves as flange receiving surface  330  for receiving the rear surface of cylinder flange  211 . 
     Grip portion  325  is formed at the leading end of each arm portion  322  for manipulation by a user when flange adapter  300  is mounted or demounted. Part of an inward surface of grip portion  325  is located on the extension of the arc shape of inner circumferential surface  321   a  of arc-shaped portion  321 . Thus, flange lock member  320  has the shape for receiving cylinder flange  211  on the inner side as a whole and provides a flange receiver matching the shape of cylinder flange  211  for removably receiving part of cylinder flange  211  together with flange receiving surface  330 . A pair of arm portions  322  are located on both sides of the left and right of cylinder flange  211  received by this flange receiver. 
     Next, description will be made of cylinder flange  211  of syringe  200  held by syringe adapter  300 . 
     As shown in  FIG. 6 , cylinder flange  211  formed at the trailing end of cylinder  210  is basically formed to have diameter D, but its opposite portions are cut in parallel. Thus, the outer circumferential edge of cylinder flange  211  is shaped to have two cut portions  213  formed at the opposite positions and arc-shaped portions  212  connecting the cut portions  213 . Distance A between cut portions  213  is smaller than diameter D of arc-shaped portion  212 . Two concave portions  212   a  are formed on the outer circumferential surface of arc-shaped portion  212  at the positions rotated 90 degrees with respect to cut portions  213  to be symmetric about center O of cylinder flange  211 . 
     Referring again to  FIG. 3  and  FIG. 4 , each arm portion  322  of flange lock member  320  has lock hook  323  as a flange lock mechanism. Lock hook  323  extends from grip portion  325  toward arc-shaped portion  321  and is supported on grip portion  325  such that look hook  323  is elastically displaced outward. Protruding portion  323   a  protruding inward is formed at the end of each lock hook  323 . Protruding portion  323   a  is formed to have dimensions engaging with concave portion  212   a  of cylinder flange  211  shown in  FIG. 6 . The distance between two protruding portions  323   a  is greater than distance A between cut portions  213  of cylinder flange  211  and to be smaller than diameter D of arc-shaped portion  212 . 
     As shown in  FIG. 7A , when syringe  200  is inserted into syringe adapter  300  in the orientation in which cut portions  213  of cylinder flange  211  are opposite to lock hooks  323 , syringe  200  can be inserted into syringe adapter  300  without interference with lock hooks  323  until arc-shaped portion  212  of cylinder flange  211  abuts on arc-shaped portion  321  of flange lock member  320 . In this state, when cylinder  200  is rotated 90 degrees about its axis, arc-shaped portion  212  of cylinder flange  211  abuts on lock hook  323  to displace elastically lock hook  323  outward, and finally, as shown in  FIG. 7B , the protruding potion of lock hook  323  engages with concave portion  212   a  of cylinder flange  211  to lock syringe  200  elastically. 
     The force applied to lock syringe  200  by lock hook  323  is preferably set such that syringe  200  is not rotated in the subsequent connection of extension tube  230  to syringe  200  (see  FIG. 2 ) and the like but can be rotated by an adequate force when the user attempts to rotate syringe  200  in order to release the engagement of lock hook  323  and concave portion  212   a.    
     As described above, syringe adapter  300  is mounted on adapter receiver  114   a  of injection head  110  (see  FIG. 2 ). Adapter receiver  114   a  is formed as a concave portion for inserting cylinder adapter  300  and has guide grooves  117  on both sides for guiding the insertion of cylinder adapter  300  as shown in  FIG. 8  and  FIG. 9 . Each of guide grooves  117  is formed to extend in the insertion direction of syringe adapter  300  (see  FIG. 3 ) between two ribs  115  and  116  formed in the inner surface of adapter receiver  114   a  to extend in the insertion direction of syringe adapter  300 . In  FIG. 8  and  FIG. 9 , the direction indicated by each arrow represents the leading end of the syringe. 
     On the other hand, as shown in  FIG. 5 , base member  310  of syringe adapter  300  has ribs  312  formed on both sides in the width direction of base member  310  for insertion into the abovementioned guide grooves  117 . 
     In addition, as shown in  FIG. 3  and  FIG. 4 , each of arm portions  322  of flange lock member  320  has engagement hook  324  serving as an adapter lock mechanism formed on the outer surface. In association therewith, as shown in  FIG. 8  and  FIG. 9 , adapter receiver  114   a  has engagement hook  118  serving as an engagement structure for locking syringe adapter  300  in cooperation with the adapter lock mechanism. Engagement hook  324  and engagement hook  118  are formed to have the position relationship and the shapes to engage with each other when syringe adapter  300  is inserted to a predetermined position in adapter receiver  114   a.    
     The engagement and the disengagement of engagement hook  324  of syringe adapter  300  and engagement hook  118  of adapter receiver  114   a  are achieved since at least the portions of flange lock member  320  that have engagement hooks  324  formed thereon are supported to be elastically displaceable inward, preferably arm portions  322  of syringe adapter  300  are supported to be elastically displaceable inward (see open arrows in  FIG. 4 ). 
     For realizing the elastic displacement, in the present embodiment, the entire flange lock member  320  is formed of a material having elasticity to the extent that engagement hook  324  is elastically deformed to engage with engagement hook  118  of adapter receiver  114   a . Example of the material having such elasticity include polyamide, polycarbonate, polyacetal, resin material such as ABS, and metal material such as phosphor bronze. Since the formation of the entire flange lock member  320  of the elastic material can simultaneously achieve the elastic displacement function of lock hook  323  described above, flange lock member  320  can be constructed of one part, and the structure of flange lock member  320  is simplified. 
     Alternatively, when engagement hook  324  is formed in arm portion  322  as in the present embodiment, only arm portion  322  of flange lock member  320  may be made of an elastic material. Alternatively, arm portion  322  may be formed as a separate part which is elastically urged by a spring or the like toward the other portions, and in this case, the materials of the parts are not limited particularly. 
     In any case, when the user attempts to take syringe adapter  300  inserted in adapter receiver  114   a  out of adapter receiver  114   a , the user holds grip portions  325  on both sides to displace arm portions  322  inward to release the engagement of engagement hook  324  and engagement hook  118 . At this point, when arm portions  322  are displaced more than necessary, flange lock member  320  may be broken. To avoid this, in the present embodiment, as shown in an enlarged view in  FIG. 10 , abutting surfaces  313  and  327  oppositely placed at an interval between them are formed as a stopper structure on base member  310  and flange lock member  320 , respectively, in order to limit the inward displacement amount of arm portions  322 . When arm portions  322  are displaced inward (to the left in  FIG. 10 ), abutting surfaces  313  and  327  abut on each other, and arm portions  322  are not displaced further. This prevents any breakage of arm portions  322  due to extreme displacement. 
     Arm portion  322  also has inclined rib  326  formed at the position located on the extension of rib  312  formed on base member  310  and corresponding to the top end of guide groove  117  when cylinder flange  300  is inserted into adapter receiver  114   a . Inclined rib  326  is formed such that its end less close to rib  312  is inclined toward inner rib  115  of ribs  115  and  117  shown in  FIG. 8 , and when arm portions  322  are displaced inward with cylinder adapter  300  inserted in adapter receiver  114   a , the inside surface of inclined rib  326  abuts on the top end of rib  115 . 
     While  FIG. 10  shows only one of arm portions  322 , the other arm  322  is constructed in the same manner. 
     Next, description will be made of the mounting and demounting operation of syringe  200  on and from injection head  110  with syringe adapter  300  described above. 
     The user first holds grip portions  325  on both sides of syringe adapter  300  and mounts syringe adapter  300  on adapter receiver  114   a  of injection head  110 . The mounting of syringe adapter  300  on adapter receiver  114   a  is performed by the engagement of engagement hooks  118  formed on adapter receiver  114   a  and engagement hooks  324  formed on arm portions  322  resulting from the inward elastic displacement of arm portions  322 . This engagement causes syringe adapter  300  to be locked within adapter receiver  114   a . Thus, syringe adapter  300  can be mounted with extreme ease only by inserting syringe adapter  300  into adapter receiver  114   a  until the engagement is achieved. 
     Syringe adapter  300  has rib  312  formed thereon. Since rib  312  is guided into guide groove  117  formed in adapter receiver  114   a , the insertion into adapter receiver  114   a  can be performed smoothly. In addition, with rib  312  formed on syringe adapter  300 , when syringe adapter  300  is in an opposite orientation, rib  312  serves as an obstacle and syringe adapter  300  cannot be inserted into adapter receiver  114   a . This prevents the mounting of syringe adapter  300  in an erroneous orientation. 
     After syringe adapter  300  is mounted, the user mounts syringe  200  on syringe adapter  300 . The mounting of syringe  200  can be performed as follows. 
     First, as shown in  FIG. 7A , the user inserts syringe  200  between arm portions  322  of syringe adapter  300  until arc-shaped portion  212  of cylinder flange  211  abuts on arc-shaped portion  321  of flange lock member  320 . At this point, syringe  200  is inserted in the orientation where cut portions  213  of cylinder flange  211  are opposite to lock hooks  323 , thereby inserting syringe  200  smoothly. Since syringe adapter  300  is formed in U shape as a whole and has the wide opening between arm portions  322  into which syringe  200  is inserted, syringe  200  is easily inserted. 
     After syringe  200  is inserted, the user rotates syringe  200  about its axis. At this point, the outer circumferential surface of cylinder  210  is supported in concave portion  114  of injection head  110 , and arc-shaped portion  212  of cylinder flange  211  and arc-shaped portion  321  of flange lock member  320  having substantially the same radius of curvature abut on each other, so that syringe  200  is rotated smoothly with the rotation center position maintained. 
     When syringe  200  is rotated to locate arc-shaped portion  212  of cylinder flange  211  at the position opposite to lock hook  323 , lock hook  323  is pushed by arc-shaped portion  212  and is elastically displaced outward. When syringe  200  is further rotated and concave portion  212   a  of cylinder flange  211  reaches the position opposite to the protruding portion at the end of lock hook  323  as shown in  FIG. 7B , lock hook  323  returns and engages with concave portion  212   a  of cylinder flange  211 . This locks and holds syringe  200  in syringe adapter  300 . The lock of syringe  200  is achieved by the engagement of lock hook  323  and concave portion  212   a , and the click feel at the time of the engagement allows the user to recognize the lock of syringe  200  reliably, for example even when injection head  110  is located at a high position and the user cannot check visually the lock of syringe  200 . 
       FIG. 11  shows the state in which cylinder  210  is mounted on injection head  110  with syringe adapter  300  interposed between them. 
     Once syringe  200  is held in this manner, the mounting of syringe  200  on injection head  110  is completed. Then, the user connects connection tube  230  to the leading end of syringe  200  and operates chemical liquid injector  100  as appropriate to allow the injection of the chemical liquid filled in syringe  200  into the patient. 
     The demounting of syringe  200  from syringe adapter  300  may be performed by reversing the series of operations described above. Specifically, the user rotates syringe  200  to release the engagement of lock hook  323  and cylinder flange  211 , and in this state, the user pulls up syringe  200  out of syringe adapter  300 . 
     As described above, according to syringe adapter  300  of the present embodiment, the mounting and demounting of syringe  200  can be performed with extreme ease. In addition, since the mounting and demounting of syringe  200  involves the rotation operation of syringe  200 , unintentional removal of syringe  200  can be prevented. 
     For removing syringe adapter  300  mounted on injection head  110 , the user manipulates grip portions  325  of syringe adapter  300 . Specifically, the user holds grip portions  325  on both side of syringe adapter  300  to displace arm portions  322  inward (in the direction in which they move closer to each other). This causes engagement hook  324  to be removed from engagement hook  118  of adapter receiver  114   a . In this state, the user pulls out syringe adapter  300  in the direction in which syringe adapter  300  is removed from adapter receiver  114   a , so that the user can remove syringe adapter  300 . 
     As described above, inclined rib  326  is formed on arm portion  322 , and when arm portion  322  is displaced inward, inclined rib  326  abuts on the top end of rib  115  formed on adapter receiver  114   a . At this point, the force applied to inclined rib  326  by rib  115  causes cylinder adapter  300  to receive the force in an upward direction in  FIG. 10 , that is, in the direction in which syringe adapter  300  is removed from adapter receiver  114 . Consequently, when arm portion  322  is displaced inward, syringe adapter  300  is raised from adapter receiver  114   a  to facilitate the removal of syringe adapter  300 . 
     As described above, part of the inward surface of grip portion  325  provided for arm portion  322  is located on the extension of the arc shape of arc-shaped portion  321  having the radius of curvature corresponding to the diameter of cylinder flange  211 . Thus, in the state in which cylinder flange  211  is received inside flange lock member  320 , part of the inward surface of grip portion  325  interferes with the outer circumferential surface of cylinder flange  211 , so that arm portion  322  cannot be displaced inward (in the direction in which they move closer to each other) until the engagement of engagement hook  324  and engagement hook  118  is released. As a result, in the state in which syringe  200  is held in syringe adapter  300 , syringe adapter  300  cannot be removed from adapter receiver  114   a , and this also prevents unintentional removal of syringe  200  mounted on injection head  110 . 
       FIG. 12  and  FIG. 13  show syringe adapter  400  according to another embodiment of the present invention. 
     Syringe adapter  400  shown in  FIG. 12  and  FIG. 13  also has a base member and a flange lock member which may be formed integrally, as in the embodiment described above, and can be mounted removably on adapter receiver  114   a  of injection head  110  shown in  FIG. 2 . Thus, the structure associated with adapter receiver  114   a  for mounting is the same as that in the embodiment described above. In the following, the same characteristics of syringe adapter  400  according to the present embodiment as those in the embodiment described above are omitted and only the different characteristics will be described. 
     Syringe adapter  400  according to the present embodiment holds a syringe (not shown) having a smaller diameter than that of syringe  200  held by syringe adapter  300  described above. When the syringe having the smaller diameter is mounted on injection head  110 , a cylinder of the syringe is raised from concave portion  114  of injection head  110 . To address this, in the present embodiment, cylinder support portion  414  for supporting the cylinder is formed integrally with the base member. Cylinder support portion  414  is formed in generally semicylindrical shape extending on concave portion  114  of injection head  110  when cylinder support portion  414  is mounted on injection head  110 . The radius of the inner circumferential surface of cylinder support portion  414  is substantially equal to the radius of the outer circumferential surface of the cylinder to be held. This enables the stable support of the syringe having the smaller diameter on injection head  110 . 
     Two plate-shaped portions  415  opposite to flange receiving surface  430  at an interval between them are formed on the base member on both sides in the width direction of the base member. The interval between flange receiving surface  430  and plate-shaped portion  415  is larger than the thickness of the cylinder flange, and the cylinder flange can be held between flange receiving surface  430  and plate-shaped portion  415 . With plate-shaped portion  415  formed on the base member, rib  412  serving as a guide in mounting syringe adapter  400  on the injection head is formed on the outer wall surface of plate-shaped portion  415 . 
     In correspondence with plate-shaped portion  415 , two plate-shaped portions  428  opposite to flange receiving surface  430  at an interval between them are also formed on the flange lock member on both sides in the width direction of the flange lock member. In association therewith, inclined rib  426  is formed on the outer wall surface of plate-shaped portion  428 . 
     These plate-shaped portions  415  and  428  are formed to have the function as a stopper which prevents extreme displacement of arm portions  422  by the abutment of the end faces of the plate-shaped portions when arm portions  422  are to be displaced extremely. 
     Lock hook  423  serving as a flange lock mechanism is supported to be elastically displaceable on an arc-shaped portion and extends therefrom toward arm portion  422  along the arc-shaped portion. In this manner, the form of the flange lock mechanism is different from the flange lock mechanism of syringe adapter  300 , but the function and the mounting/demounting operation of the syringe are similarly performed. It should be noted that the flange lock mechanism according to the present embodiment can be applied to the flange lock mechanism of syringe adapter  300  described above, and vice versa. 
     As described above, the plurality of types of syringe adapters  300  and  400  can be provided corresponding to the syringes to be held, so that various syringes can be mounted on the injection head. In addition, since the functions of the lock mechanism to the injection head and of the lock mechanism of the syringe are common to syringe adapters  300  and  400 , the syringe can be held tightly and can be mounted and demounted easily. 
     When the plurality of types of syringe adapters  300  and  400  are used in this manner, it is convenient to allow the injection head to identify easily which of syringe adapters  300  and  400  is mounted on the injection head, that is, which syringe is mounted on the injection head, and whether syringe adapter  300  or  400  is mounted. Thus, syringe adapters  300  and  400  preferably have adapter identifying members used to identify the types of syringe adapters  300  and  400 . 
     In the following, a preferred embodiment of the adapter identifying member will be described with reference to  FIG. 4  by taking syringe adapter  300  described first as an example. 
     Syringe adapter  300  is formed to be able to have up to four subjects to be detected  351   a  to  351   d  as the adapter identifying member. At least one of the number, the positions, the material, and the attachment method of the subjects to be detected  351   a  to  351   d  varies among the types of the syringe adapter. On the other hand, the injection head has at least one sensor for detecting the subjects to be detected  351   a  to  351   d  individually at the position opposite to the position where the subjects to be detected  351   a  to  351   d  can be attached in the state in which syringe adapter  300  is mounted. Which syringe adapter is mounted can be identified from the combination of the subjects to be detected  351   a  to  351   d  detected by the sensor. When any of the subjects to be detected  351   a  to  351   d  is not detected at any position, it is determined that no syringe adapter is mounted. 
     While the four subjects to be detected  351   a  to  351   d  can be provided in the present embodiment, the positions and the number of the subjects to be detected  351   a  to  351   d  are not limited particularly and can be set as appropriate in view of the type of the syringe adapter mounted on the injection head. For example when a small number of the types of syringe adapters are used, the number of subjects to be detected can be reduced accordingly. When a large number of the types of syringe adapters are used and cannot be dealt with by only the four subjects to be detected, the number of the subjects to be detected can be increased to more than four. 
     The adapter identifying member can be formed of various materials such as metal and plastic. The sensor for detecting the adapter identifying member can be realized by using an arbitrary sensor capable of detecting the adapter identifying member when syringe adapter  300  is appropriately mounted. Particularly, a proximity sensor for detecting the presence or absence and the position of an object in a non-contact manner can be preferably used. A representative proximity sensor uses magnetism as a detection medium to detect the presence or absence and the position of an object. The types of the magnetism detected by the proximity sensor include a direct-current static magnetic field and an alternating-current magnetic field. 
     When the proximity sensor using the direct-current magnetic field as the detection medium is used as the sensor, a magnet can be used as the adapter identifying member. As the proximity sensor capable of detecting the magnet, it is possible to use a semiconductor magnetic sensor such as a magnetic resistance element and a hall element, and a ferromagnetic sensor such as a flux gate type sensor, an MR (Magnet-Resistive) element, and an MI (Magneto-Impedance) element. 
     The proximity sensor for detecting the direct-current static magnetic field detects the polarity of the magnet. Thus, at least one magnet is placed as the adapter identifying member such that the orientation of the polarity is different for each type of the syringe adapter. Since the sensor detects the polarity of the magnet, it is possible to identify which syringe adapter is mounted from the combination of the detected polarities of the magnets. In this case, however, since the sensor detects the polarity of the magnet, correct detection cannot be performed if the magnet is attached with the polarity reversed due to errors in operation. 
     On the other hand, in the proximity sensor using the alternating-current magnetic field as the detection medium, metal can be used as the adapter identifying member, and no problem occurs from the errors in operation as described above. In addition, since the proximity sensor using the alternating-current magnetic field as the detection medium can detect the adapter identifying member at a distance smaller than that of the proximity sensor using the direct-current static magnetic field as the detection medium, the former can detect that the syringe adapter is mounted at the normal position more correctly. Consequently, in the present invention, the proximity sensor using the alternating-current magnetic field as the detection medium is preferably used as the sensor for detecting the adapter identifying member. 
     The proximity sensor using the alternating-current magnetic field as the detection medium has a coil and takes advantage of the fact that passing a certain alternating current through the coil by an alternating-current power source to provide the alternating-current magnetic field for the metal (adapter identifying member) produces eddy currents in the metal. The eddy currents produced in the metal cause a magnetic field to produce an induced voltage in the coil. As a result, when the metal is brought closer to the coil, the impedance of the coil which is the ratio of the voltage produced in the coil to the current passed through the coil is changed. The proximity sensor uses the change in the impedance to detect the metal. 
     The proximity sensor of this type is broadly classified into a single coil type in which one coil has the function as an excitation coil providing the alternating-current magnetic field for the adapter identifying member and the function as a detection coil detecting the eddy current magnetic field produced from the adapter identifying member and a multi coil type in which a plurality of coils are provided. 
     Examples of the type of the proximity sensor of the single coil type include a high-frequency oscillation type and a filter type. The proximity sensor of the high-frequency oscillation type incorporates a detection coil in part of an oscillation circuit and detects a change in the oscillation amplitude or the oscillation frequency in accordance with a change in impedance. The proximity sensor of the filter type incorporates a detection coil in part of an LC or LR filter circuit and uses the fact that the filter characteristics vary with a change in impedance of the detection coil. 
     Examples of the types of the proximity sensor of the multi coil type include a double coil type, a differential coil type, and a fork coil type. 
     The proximity sensor of the double coil type uses two coils of the same structure, in which one of them is brought closer to the adapter identifying member as the detection coil and the other is used as a reference coil and placed to avoid any influence of the adapter identifying member. When the two coils are excited under the same conditions and the difference in induced voltage is compared, it can be said that the difference in the induced voltage between them is produced by the approach of the adapter identifying member since the detection coil is affected by the approach of the adapter identifying member. A detection circuit is typically realized by constructing an impedance bridge with the two coils and exciting it through a fixed oscillator to detect the amplitude of the unbalanced voltage or the phase to the exciting current. Alternatively, the unbalanced voltage obtained from the bridge circuit is amplified and fed back to the excitation side of the bridge circuit to oscillate the circuit, and the resulting amplitude is detected. 
     In the proximity coil of the differential coil type, typically, detection coils are placed at symmetric positions on both sides of an excitation coil, and the terminals of the detection coils are connected in the series with the reverse polarities and are used as a detection output end. Since the excited magnetic flux produces the equal induced voltage in the detection coils, the induced voltage due to the excited magnetic field is cancelled, and only the induced voltage due to the magnetic flux produced by eddy currents can be taken out similarly to the double coil type. Then, similarly to the double coil type, it is only required to detect the amplitude or the phase of the output voltage at the terminal of the detection coil, or to amplitude the voltage at the terminal of the detection coil, feed it back to the excitation coil, and oscillate it. 
     In the proximity sensor of the fork coil type, the excitation coil and the detection coil are placed opposite to each other to make magnetic coupling, and the adapter identifying member is inserted between them to detect a change in the amplitude or the phase of the induced voltage produced in the detection coil. 
     Description has been made of various proximity sensors capable of detecting the metal in a non-contact manner by using the alternating-current magnetic field as the detection medium. Any of them can be used in the present invention. When the proximity sensor capable of detecting the metal is used, the adapter identifying member may be formed of metal entirely or partially. 
     The size and the shape of the adapter identifying member can be arbitrarily set as long as it does not interfere with the mounting of syringe adapter  300 . Preferably, the adapter identifying member may be a ball plunger. 
     When the ball plunger is used as the adapter identifying member, the ball plunger is preferably attached such that part of a ball thereof is protruded from the surface of syringe adapter  300 . On the other hand, adapter receiver  114   a  is preferably provided with a concave portion or a through hole for accommodating the proximity sensor at the position opposite to the ball plunger in the state in which syringe adapter  300  is mounted on adapter receiver  114   a  such that the ball of the ball plunger engages with the concave portion or the through hole. This allows the adapter detecting means to have an auxiliary lock function of syringe adapter  300  to adapter receiver  114   a.    
     As described above, the proximity sensor can be placed within the concave portion or the through hole formed in adapter receiver  114   a . In this case, the proximity sensor may be held through press fit into the concave portion or the through hole or may be held through screwing. The holding of the proximity sensor through screwing can facilitate the position adjustment of the proximity sensor within the concave portion or the through hole and the removal of the proximity sensor for replacing. The concave portion or the through hole may be filled with resin. This can increase resistance to water of the proximity sensor to reduce the possibility of a failure of the proximity sensor when the chemical liquid or the like is attached thereto. 
     While the syringe adapter has been described by using the representative embodiments as examples, the syringe adapter according to the present invention is not limited to the abovementioned embodiments, and the structure, the size and the like of the flange receiver and the flange lock mechanism can be changed as appropriate depending on the shape, the size and the like of the cylinder flange of the syringe to be held. For example, in the abovementioned embodiments, the cylinder flange of the syringe held by the syringe adapter has the two concave portions on the outer circumferential surface, and the flange lock mechanism is formed so as to fit to the concave portions. However, the number of the concave portions formed in the cylinder flange may be one, or three, four, or more. In this case, the position, the number and the like of the flange lock mechanism can be changed in accordance with the concave portion formed in the cylinder flange. 
     While the abovementioned embodiments have been described with the case in which the syringe adapter is applied to the chemical liquid injector, the syringe adapter of the present invention can be applied to a chemical liquid filler for filling a chemical liquid into an empty syringe. 
     DESCRIPTION OF REFERENCE NUMERALS 
     
         
           100  CHEMICAL LIQUID INJECTOR 
           110  INJECTION HEAD 
           114   a  ADAPTER RECEIVER 
           117  GUIDE GROOVE 
           118  ENGAGEMENT HOOK 
           200  SYRINGE 
           210  CYLINDER 
           211  CYLINDER FLANGE 
           212   a  CONCAVE PORTION (OF CYLINDER FLANGE) 
           220  PISTON 
           300 ,  400  SYRINGE ADAPTER 
           310  BASE MEMBER 
           312 ,  412  RIB 
           313 ,  327  ABUTTING SURFACE 
           320  FLANGE LOCK MEMBER 
           321  ARC-SHAPED PORTION (OF FLANGE LOCK MEMBER) 
           322 ,  422  ARM PORTION 
           323 ,  423  LOCK HOOK 
           324  ENGAGEMENT HOOK (OF FLANGE LOCK MEMBER) 
           325  GRIP PORTION 
           326 ,  426  INCLINED RIB 
           330 ,  430  FLANGE RECEIVING SURFACE 
           414  CYLINDER SUPPORT PORTION 
           415 ,  428  PLATE-SHAPED PORTION