Abstract:
Timing of movements of a spring between a stressed and a free state is delayed by dampening the spring movement through incorporation of a component having a restricted access diameter whereby frictional contact of the spring through the component will prolong the time required to move the spring between states to enhance control of the spring actuation.

Description:
TECHNICAL FIELD  
         [0001]    The present invention relates in general to data processing systems, and in particular, to a device for controlling the time of actuation of a spring which may be incorporated, for example, in a disposable safety syringe or catheter.  
         BACKGROUND INFORMATION  
         [0002]    Springs are commonly used as a power source for the actuation of an auxiliary component or device. However, springs have one characteristic which is unattractive in many applications. The amount of force which is generated by the spring when it is moved between stressed and free states is a largely linear function of the amount by which the spring has been compressed or expanded from its free state. Accordingly, when the spring is released, the spring generates its maximum amount of force at the instant of release, and the force declines linearly as the spring recovers to its free state.  
           [0003]    In many applications, this sudden acceleration is undesirable. For example, in U.S. Pat. No. 5,053,010, entitled “Safety Syringe with Retractable Needle,” issued Oct. 1, 1991, there is shown and disclosed an improved safety syringe with retractable needle which allows retraction of the needle into a hollow plunger by forward pressure on the plunger after fluid is driven from the syringe into the patient. The syringe includes a hollow plunger which is inserted into one end of a cylindrical barrel and a hollow needle attached to the other end of the barrel. Actuation of the plunger subsequent to injection of the fluid within the barrel into the patient will cause the compressive bias within a spring mechanism to be applied against a carrier for the shifting of the needle into the interior of the hollow plunger. If liquid, such as medicine, still is contained within the interior of the hollow needle during the retraction step, the sudden acceleration of the needle in a backward-like direction into the interior of the plunger may, depending upon on the amount, viscosity, temperature, pressure and other variables, cause or contribute to considerable quick ejection out of the open end of the needle of such fluid, resulting in spillage onto the patient, operator, or floor immediate the area of positioning of the syringe. A similar situation could occur when the device to be actuated by the spring biasing mechanism is provided in the form of a catheter. The present invention addresses the problems set forth above.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention provides a device for delivering energy which is stored in a spring which is to be moved between stressed and free states. The “stressed” state may be either compressed or expanded position or state. “Free” state is that condition that the biasing spring is in subject to substantially complete activation and may also be compressed or expanded in that condition. Thus, the “stressed” state is that state of the biasing spring prior to actuation, while the “free” state is that condition of the biasing spring subsequent to a completion of actuation.  
           [0005]    The device includes a housing having an inner cylindrical wall of a given diameter. A continuous length of compressible spring, preferably provided in a continuously coiled or spiraled length, is stored in the housing and is positionable therein and along at least a portion of the wall in one of the stressed and free states, with the spring having an outer surface of a given diameter which is disposed along the continuous length of the spring. Means are provided for selectively actuating movement of the spring from one of the stressed and free states to the other of the said states and within the housing. Dampening means are provided for controlling the rate of movement, or the time of the movement, of the spring between the states and the actuation of the auxiliary component.  
           [0006]    The dampening means may preferably comprise an elongated collar which is operatively positionable relative to the housing and includes an inner wall along the entire elongate. The collar has first and second open ends through which the spring is disposed. The collar further defines a restricted diameter passageway therethrough with the diameter of the restricted passageway being less than the diameter of the outer surface of the spring, such that the outer surface of the coils of the spring frictionally engages the inner wall of the collar to delay movement of the spring therethrough.  
           [0007]    The device of the present invention may be incorporated into a non-reusable retractable safety syringe. Such a syringe may be provided wherein a cylindrical barrel, having first and second barrel ends and an inner diameter wall, defines a chamber which further receives fluid, such as medicine. A plastic hollow plunger extends into the barrel through the first end and is moveable from an expandable position toward an expended position. A hollow needle is secured relative to the second end of the barrel and a spring component incorporating the dampening means of the present invention is initially compressed in stressed state to provide energy for moving the hollow needle interior of the barrel and within the plastic hollow plunger subsequent to the plunger being moved to the expended position.  
           [0008]    The invention may also be utilized in a catheter in which a hollow needle may telescopically contract relative to an outer cylindrical housing subsequent to use.  
           [0009]    The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:  
         [0011]    [0011]FIG. 1 is a horizontal cross-sectional view of the device of the present invention, illustrating a compressed spring in its stressed state being moved through a dampening means luring operation;  
         [0012]    [0012]FIG. 2 is a cross-sectional view of the collar component of the device of FIG. 1;  
         [0013]    [0013]FIG. 3 is a view similar to that of FIG. 1, with a spring shown in expanded state actuating against the wall of an auxiliary component, with the spring shown in its free state;  
         [0014]    [0014]FIG. 4 is a horizontal cross-sectional view of a safety syringe incorporating the device of the present invention;  
         [0015]    [0015]FIG. 5 is an enlarged detail view of the device of the present invention shown in the safety syringe of FIG. 4;  
         [0016]    [0016]FIG. 6 is a horizontal sectional view of an alternative preferred embodiment of the device shown in FIG. 5;  
         [0017]    [0017]FIG. 7 is a view similar to that of FIG. 6, showing yet another alternative preferred embodiment of the present invention;  
         [0018]    [0018]FIG. 8 is a horizontal cross-sectional view of a catheter incorporating the device of the present invention;  
         [0019]    [0019]FIG. 9 is a horizontal sectional view, constituting an enlargement of a portion of the device shown in FIG. 8; and  
         [0020]    [0020]FIG. 10 is an alternative preferred embodiment of the design of the device of the present invention as shown in FIGS. 8 and 9.  
     
    
     DETAILED DESCRIPTION  
       [0021]    In the following description, numerous specific details are set forth such as specific word or byte lengths, etc. to provide a thorough understanding of the present invention. However, it will be obvious to those skilled in the art that the present invention may be practiced without such specific details. In other instances, well-known circuits have been shown in block diagram form in order not to obscure the present invention in unnecessary detail. For the most part, details concerning timing considerations and the like have been omitted in as much as such details are not necessary to obtain a complete understanding of the present invention and are within the skills of persons of ordinary skill in the relevant art.  
         [0022]    Refer now to the drawings wherein depicted elements are not necessarily shown to scale and wherein like or similar elements are designated by the same reference numeral through the several views.  
         [0023]    Now, with first reference to FIG. 1, there is shown the device  10  in horizontal, cross-sectional view. The device  10  includes an outer elongated cylindrical housing  100  having at one end thereof a closed end surface  102  and at the opposite end an opening  103  through which may be introduced during manufacture, a length of compressible spring  106 , typically made of a metallic or plastic substance sufficient to be moved from stressed to free states without breakage, and farther, which is capable of storing compressive energy therethrough. The spring  106  has a terminating first end  107  which is housed within the housing  100  against the closed end  102 .  
         [0024]    As shown in FIG. 1, the spring  106  is positioned within the housing  100  in stressed state SS. The housing has a diameter indicated by line  105 . In the stressed state SS and within the housing  100 , the outer surface  109  of the spring  106  may, or may not, come into contact with the inner wall  104  of the housing  100 , but it there is contact, it is casual and not sufficient to interfere with spring actuation, as the housing  100  only serves to contain the spring, not interfere with its operation. The spring  106  has a second end  108  which typically will abut against an auxiliary component AC (FIG. 3) having an inner wall AC- 1 . The spring  106  may thus cause movement of the auxiliary component AC, or the housing  100 , depending upon component organization and a particular operation at hand.  
         [0025]    A collar  110  is provided which, as shown, may-be of circular or similar shape, the particular shape of the collar  110  not being particularly critical to the present invention. The collar  110  has an opening  115  therethrough through which the spring  106  may pass. The collar  110  has first and second open ends  114 ,  115  through which the coils or loops  106 A of the spring may pass during actuation.  
         [0026]    Now with reference to FIG. 2, the spring  106  has an outside diameter  111  and the collar  110  has a restricted passageway  116  therethrough such that the diameter of the restricted passageway  116  is somewhat smaller than the spring outside diameter II I and, preferably, the housing diameter  105  (assuming that the collar  110  and the housing  111  are in lateral alignment, as shown in FIG. 1). As the spring moves from the position shown in FIG. 1 to the position shown in FIG. 3, it will now be appreciated that the coil s  106 A of the spring  106  must pass through the opening, or restricted passageway  116  and the collar  110 . The friction resulting between the contact of the coils  106 A and the inner wall  113  of the collar  110  will “meter” or dampen movement of the spring  106  therethrough, causing a time delay of the actuating force in the spring  106 . The difference in the diameter of the spring  106  and that afforded through the restricted passageway  116  and defined by the inner wall  113  thereof controls a rate of recovery of the spring  106  by requiring the coils or loops  106 A of  10  the spring  106  to wind its way through the orifice, metering means, or collar  110 .  
         [0027]    It has been experimentally determined that, for instance, a compression spring with an outside diameter of 0.285 inches will recover almost instantaneously through a spring controlled orifice with a diameter equal to or larger than 0.285 inches. As the spring control orifice is reduced in relative diameter, the spring recovery rate declines and the recovery period increases. With an orifice diameter of 0.266 inches (a 7% occlusion) the recovery period of the spring increases to about ½second. With an orifice diameter of 0.242 inches (a 15% occlusion), the recovery period of the spring increases to almost 2 seconds. Thus, by controlling the orifice, the time required for the winding of the spring from stressed to free state may be dramatically extended, while not adversely affecting the compressive biased energy stored or to be stored in the spring.  
         [0028]    Now with reference to FIG. 4, there is shown a non-reusable retractable safety syringe  300  incorporating the device  10  of the present invention. A cylindrical barrel  301  is provided which receives at a second open barrel end  303  a hollow plunger  307 . The cylindrical barrel  301  also has a first barrel open end  302  through which is projected a retractable hollow needle  309  which is biased towards telescopically contracted state relative to the barrel  301  and plunger  307  by means of a compressed spring  310 . The syringe  300  includes a chamber  305  therein for receipt of fluid which is ejected out of the open end  309 A of the needle  309  during operation. An elastomeric seal  306  is disposed on one end of the hollow plunger  307  for movements against a smooth inside diameter wall  304  of the cylindrical barrel  301  to eject liquid completely out of the spring  300 .  
         [0029]    Now with reference to FIG. 5, the dampening means is shown as provided by means of a collar or doughnut  311  which is geometrically provided in the form of a half-circle having a first inner surface  311 A for contacting engagement of a first coil surface  310 A of a spring  310 , with one end  310 B of the spring  310  shouldered against a surface  312 A of a needle carrier  312  disposed around one end of a hollow needle  313 . The first surface  311 A of the collar  311  extends inwardly of the inner wall  314  of a companion housing member  315  to resist movements of the spring coils  310 A there across.  
         [0030]    A similar design for a metering means is shown in FIG. 6 in which the collar  110  is provided with a “V”-shaped orifice  117  having angled surfaces  117 A and  117 B disposed approximately 45° offset from a center line  150  of a housing component (not shown).  
         [0031]    Likewise, as shown in FIG. 7, the collar  110  may actually be angled or beveled surfaces inwardly disposed on the housing for the spring element.  
         [0032]    Now referring to FIGS. 8, 9, and  10 , there is shown the incorporation of the present invention into a catheter  400 . The catheter  400  is typical of such devices, and it comprises a hollow cylindrical body  406  and a catheter body top  407  which may be secured to the body  406  by threads  407 A, or by other convenient means. A spring  403  is provided therein having one end resting against a needle carrier  401  with a collar  410  of the design shown in FIG. 5 shown in FIG. 5 being disposed on the housing  406 . A clamp  408  is disposed interiorly of the housing member  407 , and when the clamp is released, the needle assembly may retract into the catheter body as a result of the biased compressive stress forces contained within the spring being metered through the metering means  410  to shift the housing  401  for the needle  402  inwardly of the cylindrical housing  406 . A semi-permeable membrane  405 , of known construction, is provided. The clamping device  408  may be one of any number of known- devices, such as that shown in U. S. Pat. No. 5,501,675 to Erskine.  
         [0033]    Although the invention has been described in terms of specified embodiments which are set forth in detail, it should be understood that this is by illustration only and that the invention is not necessarily limited thereto, since other alternative embodiments and operating techniques will become apparent to those skilled in the art in view of the disclosure. Accordingly, modifications are contemplated which can be made without departing from the spirit of the described invention.  
         [0034]    Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.