Abstract:
An improved syringe and spring clip therefor used in single use (aspirating and non-aspirating) syringes in which the syringe has an improved, X-shaped nose piece for assisting the attachment of a sheath and an improved spring clip for both ensuring better operation of the single use aspect of the device and for ensuring that only a predetermined amount of medicine is loaded into the syringe when the syringe is loaded with medicine.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to certain improvements in single use syringes both with and without aspirating mechanisms. 
     These improvements relate to improvements over certain prior structures which are the subject of prior patents, these being identified as U.S. Pat. No. 5,531,691, entitled Single Use Syringe Assembly, issued Jul. 2, 1996; U.S. Pat. No. 5,562,623, entitled Single Use Syringe Assembly Including Spring Clip Lock and Plunger; and, U.S. Pat. No. 6,283,941, entitled Single Use Syringe With Aspirating Mechanism. The contents of these prior patents are incorporated herein by reference. 
     These prior patents describe certain improvements relating to the single use syringes both with and without aspirating mechanisms. In the course of working with these syringe structures, certain improvements have been discovered and are the subject of this present application. These are more clearly described in the present specification and associated drawings, and are briefly summarized. 
     The prior art syringes generally have a front nose piece which is shown and described in the prior art as being cylindrical. It has been discovered that by providing an X-shaped nose piece for the front portion of the syringe, improvements in the operation, manufacturing and functioning of the syringe are achieved. The X-shaped front nose piece permits better centering of the needle on the front of the syringe, easier securement of the cover of the needle after use (to reduce needle “sticks”), and provides easier assembly of the nose piece to the barrel of the syringe because of the use of the arms of the X-shaped nose piece during assembly. 
     Further, the &#39;941 patent shows and describes a spring locking clip about the plunger, employed as described in that patent. Certain improvements have been made to that spring locking clip making it more effective to manufacture, less expensive and more efficient and secure in its use for the purposes intended in the syringe. These will be described in further detail, but overall there is an improvement in the operation achieved with the changes to the spring lock clip described herein. 
     Another improvement with respect to the prior art is the ability to ensure that the spring clip is attached at a specific location on the plunger to guarantee that the amount of medicament loading in the barrel of the syringe is always precisely predetermined, i.e., a preset amount, such as 1 cc or 0.5 cc, as appropriate. This is achieved by ensuring that the clip is located at and on a precise and exact ratchet tooth each time the clip is attached to the plunger. As a further aspect of this invention, the clip is provided with a tab which cooperates with a notch in the specific ratchet tooth location so that when the clip is attached to the ratchet, the tab sets in the notch, and if sought to be mechanically attached at any other location, it will not properly set in place because there will be no corresponding notch. This will ensure that the clip is precisely located where desired on the plunger to control the exact amount of dosage loaded into the syringe. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cut away plan view of a syringe with an improved needle front nose piece construction. 
         FIG. 1   a  is a front plan view of the improved nose piece section of this invention. 
         FIG. 2  is a perspective view of the spring clip of this invention. 
         FIG. 3  is a sectional view through the syringe of  FIG. 1  showing the spring clip between the barrel and the plunger of the syringe. 
         FIG. 4  is a partial cut side plan view showing a specific ratchet tooth to which the spring clip is attached for controlling the amount of medication loading in the syringe. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a substantially conventional syringe  10  having an improved nose piece  12  with the needle  14  selectively covered by a sheath, cap or cover  16 . In the prior art, the nose piece was a cylindrical boss-like structure attached to the bottom of barrel  18 . The improvement of the nose piece construction is further illustrated in  FIG. 1   a  which is a front view showing the center  20  of the nose piece  12  with four fins  22  extending 90° with respect to each other. The number of fins could be selected as desired, but each of the fins has slight resilience or flexibility. As shown in  FIG. 1 , the bottom of each of the fins is slightly mitered or tapered as at  24  so that the sheath  16  may easily be guided up to and slide onto and lock with nose clip  12  by taking advantage of the slight flexibility of fins  22  and the tapered sections  124 . Such a nose piece requires less material, assists in the centering of the sheath  16  while being placed and locked on needle  14 . The outer dimension of the fins is substantially equal to the inner diameter of the sheath to ensure proper, frictional and secure attachment of the sheath. The modification to nose piece  12  will not involve any new manual manipulation by the user, as it functions, ostensibly, as the prior art nose piece except with the improvements realized and described above. The X-shape of the new nose piece also helps in automatically, i.e., by machine locating the attached needle  14 . 
       FIG. 2  is a perspective view of the spring clip which is used in the structure of the prior patents as described therein, attachable to a ratchet tooth of the plunger. The function of the spring clip is to allow for single use only of the syringe whether or not in aspirating form or otherwise. An improvement over the prior art spring clip is realized by changing the outer peripheral structure or profile of locking teeth  24  and  26  by providing a shallow U-shape connection  28  between contact points  30  and  32 . This provides improved performance for the spring lock because the prior art sharp triangular or V-shape formed between contact points resulted in a lower stress to be overcome to avoid the single use aspect of the syringe, a result to be avoided. The smoother, rounded connecting arch  28  between sharp contact points  30  and  32  provides for improved performance as the spring lock still is embedded into the side wall of the barrel but its digging-in force is not easily overcome. This prevents against more than a single use of the syringe. 
     As another feature of this invention, the prior art semi-circular tab extended distally and downwardly from back  34  of the clip (which counterbalanced upper tab  36 ) to prevent jamming of the clip during plunger movement has been eliminated. Because the finishing of the bottom tab was somewhat imperfect, it was found that the plunger would slip, occasionally, and an improvement has resulted by eliminating the bottom tab leaving the bottom wall of the back  34  co-extensive with the entire bottom of the spring clip  23 , i.e., co-planar with the other bottom walls of the clip. 
       FIGS. 3 and 4  relate to another aspect of the improvement of this invention. The improvement relates to ensuring that only a precise predetermined amount of medicine is loaded into each syringe. This is made possible by ensuring that the spring lock clip attaches at only one ratchet tooth location along the plunger. Another manner of ensuring such loading is to pre-load a certain predetermined amount of medicine during the manufacturing process relying solely upon such manufacturing controls to pre-load the syringe. Such pre-loaded syringes with preset medicines ensure the reliability of the medical injection by guaranteeing a predetermined amount of medicine is injected each and every time. But more often, syringes are provided empty, for the physician to load and dispense medication. A mechanism is needed to ensure that no more than a precise, predetermined amount of medication can be loaded, at the site of injection, by location of the spring lock clip on the plunger. The prior art did not fix the amount of loaded medicine to be a predetermined amount, and additionally, there was no additional safety to ensure that such predetermined amount was pre-loaded with no more or no less being possible. 
       FIG. 4  shows a plan elevation view partially cut away showing the plunger with a plurality of ratchet teeth and a clip attached thereto at the predetermined location. In particular, syringe  40  is shown with plunger  42  having a plurality of ratchet teeth  44  one of which is the site for spring clip  46 . The spring clip can be attached at only one ratchet because of the structure shown in  FIG. 3 . In particular, there is shown the barrel  48  of the syringe with the plunger  42  and the ratchet teeth  44  illustrated with the dotted circular lines somewhat inset from the outer edges of plunger teeth  44 . 
     The spring clip  46  is shown attached to the plunger. Further, and in accordance with this invention, an additional tab  50  is formed in the clip, depending inwardly from the inner wall of spring clip  46  to set into a recess or notch  52  formed in the specific or exact ratchet tooth location which will ensure a predetermined amount of medicine can only be loaded into the syringe to be dispensed. Because the tab  50  is integrated to the inner wall of spring clip  46 , it will be impossible for the syringe to be properly assembled unless tab  50  fits into the notch  52  of the plunger. Since notch  52  will be at only one location along the barrel (depending on the amount of maximum medication to be loaded), there is only one location for the spring clip to be set on the barrel for proper manufacture and assembly of the syringe of this invention. 
     It should be understood that the preferred embodiment was described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly legally and equitably entitled.