BACKGROUND OF THE INVENTION 
     The present invention relates to an infusion assembly and more particularly to the components of such an assembly and the assemblage thereof that enable liquid medicaments to be delivered to a patient with convenience and in a controlled manner. 
     Tight control over the delivery of insulin in both type I diabetes (usually juvenile onset) and type II diabetes (usually late adult onset), has been shown to improve the quality of life as well as the general health of these patients. Insulin delivery has been dominated by subcutaneous injections of both long acting insulin to cover the basal needs of the patient and by short acting insulin to compensate for meals and snacks. Recently, the development of electronic, external insulin infusion pumps has allowed the continuous infusion of fast acting insulin for the maintenance of the basal needs as well as the compensatory doses (boluses) for meals and snacks. These infusion systems have shown to improve control of blood glucose levels. However, they suffer the drawbacks of size, cost, and complexity. For example, these pumps are electronically controlled and must be programmed to supply the desired amounts of basal and bolus insulin. This prevents many patients from accepting this technology over the standard subcutaneous injections. 
     Hence, there is a need in the art for a convenient form of insulin treatment which does not require significant programming or technical skills to implement to service both basal and bolus needs. Preferably, such a treatment would be carried out by an infusion device that is simple to use and mechanically driven negating the need for batteries and the like. It would also be preferable if the infusion device could be directly attached to the body and not require any electronics to program the delivery rates. The insulin is preferably delivered through a small, thin-walled tubing (cannula) through the skin into the subcutaneous tissue similar to technologies in the prior art. 
     While the idea of such a simple insulin delivery device is compelling, many obstacles must be overcome before such a device may become a practical realty. One problem resides in insulin supply. Patients vary greatly on the amount of insulin such a device must carry to provide treatment over a fixed time period of, for example, three days. This is one environment where one size does not fit all. Another problem is with cannula deployment to support insulin delivery. Cannula deployment to support delivery of the insulin beneath the patient&#39;s skin must be made easy and convenient. This is not as easy as it seems because cannula deployment, as generally and currently performed in the art, requires insertion of a cannula carrying needle into the patient and then retraction of only the needle to leave the cannula in place beneath the patient&#39;s skin. As will be seen subsequently, the present invention addresses these and other issues toward providing a simple, practical, and reliable insulin delivery device. 
     SUMMARY OF THE INVENTION 
     The invention provides a cannula assembly comprising a substantially planar base having a first surface and a second surface, the first surface being opposite the second surface and adapted to adhere to a patient&#39;s skin, a cannula projecting from the base first surface so as to be beneath the patient&#39;s skin when the assembly is deployed, and a generally cylindrical docking structure having a center axis substantially perpendicular to the base second surface and arranged to receive a source of liquid medicament to be dispensed from the cannula. 
     The docking structure may include an upper surface having a septum that is arranged to receive a needle extending from the source of liquid medicament. The docking structure may have a locking structure for locking the source of liquid medicament and the docking structure together. Although the locking structure provides a true lock, it may be a releasable locking structure if desired. The docking structure is also preferably arranged to receive the source in any radial orientation. 
     The locking structure may comprise a detent. The detent may comprise a circumferential groove within the docking structure. 
     In another embodiment, the invention provides an infusion assembly. The infusion assembly comprises a cannula subassembly and a source subassembly. The cannula subassembly may include a substantially planar base having a first surface and a second surface, the first surface being opposite the second surface and adapted to adhere to a patient&#39;s skin, a cannula projecting from the base first surface so as to be beneath the patient&#39;s skin when the subassembly is deployed, and a generally cylindrical docking structure having a center axis substantially perpendicular to the base second surface and arranged to receive a source of liquid medicament to be dispensed from the cannula. The source subassembly is arranged to dock with the docking structure and includes a supply of liquid medicament that couples to the cannula upon the source subassembly docking with the cannula subassembly. 
     The docking structure may include an upper surface having a septum, the source subassembly may include a needle coupled to the supply of liquid medicament and the septum may be arranged to receive the needle of the source subassembly upon the source subassembly docking with the cannula subassembly. The docking structure may have a locking structure for locking to the source subassembly. Also, the docking structure and the source subassembly may be arranged to dock in any radial orientation. 
     The docking structure may include an upper surface having a septum communicating with the cannula that is arranged to receive the liquid medicament from the supply of liquid medicament and the source subassembly may include a housing having an opening providing an external source of liquid medicament access to the septum. The source subassembly may have a base surface adapted to adhere to the patient&#39;s skin and the base surface of the source subassembly may be separate from the cannula subassembly first surface. 
     The source subassembly may include a needle coupled to the supply of liquid medicament, the cannula may be coupled to the needle of the source subassembly upon the source subassembly docking with the cannula subassembly, and the source subassembly may further include a primer that primes the needle and cannula with the liquid medicament upon the source subassembly docking with the cannula subassembly. The source subassembly may further include a conduit coupling the needle with the supply of liquid medicament. The primer may be within the conduit. 
     The primer may comprise a collapsible reservoir within the conduit arranged to contain an amount of the liquid medicament. The reservoir may be collapsible upon the source subassembly docking with the cannula subassembly to force the liquid medicament into the needle and cannula. The docking structure may include a septum, and the septum may be arranged to receive the needle of the source subassembly upon the source subassembly docking with the cannula subassembly. The docking structure may be arranged to collapse the reservoir upon the source subassembly docking with the cannula subassembly and the docking structure and the source subassembly may be arranged to permit the septum to receive the needle prior to the docking structure collapsing the reservoir. 
     In another embodiment, an infusion assembly comprises a cannula subassembly and a source subassembly. The cannula subassembly includes a substantially planar base having a first surface and a second surface, the first surface being opposite the second surface and adapted to adhere to a patient&#39;s skin, a cannula projecting from the base first surface so as to be beneath the patient&#39;s skin when the subassembly is deployed, and a docking structure arranged to receive a source of liquid medicament to be dispensed from the cannula. The source subassembly is arranged to dock with the docking structure and includes a supply of liquid medicament that couples to the cannula upon the source subassembly docking with the cannula subassembly and a base surface separate from the cannula subassembly first surface and adapted to adhere to the patient&#39;s skin. 
     The docking structure and the source subassembly may be arranged to dock in any radial orientation. The docking structure may include an upper surface having a septum, the source subassembly may include a needle coupled to the supply of liquid medicament and the septum may be arranged to receive the needle of the source subassembly upon the source subassembly docking with the cannula subassembly. 
     The docking structure may have a locking structure for locking to the source subassembly. Again, the docking structure and the source subassembly may be arranged to dock in any radial orientation. 
     The docking structure may include an upper surface having a septum communicating with the cannula that is arranged to receive a liquid medicament from an external source of liquid medicament and the source subassembly may include a housing having an opening providing an external source of liquid medicament access to the septum. The base surface of the source subassembly may have a layer of adhesive to adhere the base surface to the patient&#39;s skin and the first surface of the cannula subassembly may have a layer of adhesive separate from the base surface layer of adhesive of the source subassembly to adhere the cannula subassembly to the patient&#39;s skin independently of the source subassembly. 
     The source subassembly may include a needle coupled to the supply of liquid medicament, the cannula may be coupled to the needle of the source subassembly upon the source subassembly docking with the cannula subassembly, and the source subassembly may further include a primer that primes the needle and cannula with the liquid medicament upon the source subassembly docking with the cannula subassembly. The source subassembly may further include a conduit coupling the needle with the supply of liquid medicament. The primer may be within the conduit. The primer may comprise a collapsible reservoir within the conduit arranged to contain an amount of the liquid medicament, the reservoir being collapsible upon the source subassembly docking with the cannula subassembly to force the liquid medicament into the needle and cannula. The docking structure may include a septum, and the septum may be arranged to receive the needle of the source subassembly upon the source subassembly docking with the cannula subassembly. The docking structure may be arranged to collapse the reservoir upon the source subassembly docking with the cannula subassembly and the docking structure and the source subassembly may be arranged to permit the septum to receive the needle prior to the docking structure collapsing the reservoir. 
     In a further embodiment, a cannula assembly comprises a cannula subassembly including a substantially planar base having a first surface and a second surface, the first surface being opposite the second surface and adapted to adhere to a patient&#39;s skin, a cannula projecting from the base first surface at a preset angle other than ninety degrees with respect to the patient&#39;s skin so as to be beneath the patient&#39;s skin when the subassembly is deployed, and a generally cylindrical docking structure having a center axis substantially perpendicular to the base second surface and arranged to receive a source of liquid medicament to be dispensed from the cannula. The assembly further comprises a cannula driver arranged to drive the cannula subassembly base first surface to a deployed position on the skin of the patient along a path defining the preset angle with respect to the patient&#39;s skin. 
     The cannula driver may include a needle carrying the cannula and be arranged to translate the needle and cannula into the deployed position beneath the patient&#39;s skin. The cannula driver may include a drive element that drives the cannula subassembly to the deployed position with the base first surface adhered to the patient&#39;s skin and the needle and cannula beneath the patient&#39;s skin and at the preset angle with respect to the patient&#39;s skin. The drive element may include a spring. 
     The cannula driver may include a needle carrying the cannula. The cannula driver may be arranged to translate the needle and cannula from the cannula driver to the deployed position, and the cannula driver may further be arranged to withdraw the needle from the cannula and return the needle to the cannula driver leaving the cannula in the deployed position projecting from the base first surface beneath the patient&#39;s skin. The cannula driver may include an inner compartment and the cannula driver may be arranged to release the needle into the inner compartment after withdrawing the needle from the cannula. 
     The cannula driver has a distal end that may be arranged to engage the patient&#39;s skin and establish the path defining the preset angle with respect to the patient&#39;s skin. The cannula driver may include a drive element that withdraws the needle from the cannula and returns the needle to the cannula driver leaving the cannula in the deployed position beneath the patient&#39;s skin. 
     The cannula driver may include an actuator which, when acted upon, causes the cannula assembly to be driven to the deployed position and a lock-out structure that precludes the actuator from being inadvertently acted upon. The lock-out structure may overlie the actuator. The lock-out structure may be a break-away cap structure. 
     The docking structure may include an upper surface having a septum that is arranged to receive a needle of the source of liquid medicament. The docking structure may further have a locking structure that locks the source of liquid medicament and the docking structure together. The locking structure may include a detent. The detent may comprise a circumferential groove. 
     The docking structure may have a locking structure for releasably locking the cannula subassembly within the cannula driver. The locking structure may comprise a detent. The detent preferably comprises a circumferential groove within the docking structure. 
     In another embodiment, an infusion assembly comprises a cannula subassembly including a base, a cannula projecting from the base so as to be beneath the patient&#39;s skin when the subassembly is deployed, and a docking structure arranged to receive a source of liquid medicament to be dispensed from the cannula. The assembly further comprises a source subassembly arranged to dock with the docking structure. The source subassembly includes a supply of liquid medicament that couples to the cannula upon the source subassembly docking with the cannula subassembly and a primer that primes the cannula with the liquid medicament upon the source subassembly docking with the cannula subassembly. 
     The source subassembly may further include a conduit coupling the cannula with the supply of liquid medicament. The primer may be within the conduit. 
     The primer preferably comprises a collapsible reservoir within the conduit arranged to contain an amount of the liquid medicament. The reservoir is collapsible upon the source subassembly docking with the cannula subassembly to force the liquid medicament into the cannula. 
     The source subassembly may include a needle coupled to the supply of liquid medicament, and the cannula may be coupled to the needle of the source subassembly upon the source subassembly docking with the cannula subassembly. The primer may then prime the needle and cannula with the liquid medicament upon the source subassembly docking with the cannula subassembly. 
     The docking structure may include a septum arranged to receive the needle of the source subassembly upon the source subassembly docking with the cannula subassembly. The docking structure and the source subassembly are arranged to permit the septum to receive the needle prior to the docking structure collapsing the reservoir. 
     In a still further embodiment, a cannula assembly comprises a cannula subassembly including a substantially planar base having a first surface and a second surface, the first surface being opposite the second surface and adapted to adhere to a patient&#39;s skin, a cannula projecting from the base first surface at a preset angle other than ninety degrees with respect to the patient&#39;s skin so as to be beneath the patient&#39;s skin when the subassembly is deployed, and a docking structure projecting from the base second surface and arranged to receive a source of liquid medicament to be dispensed from the cannula. The assembly further comprises a cannula driver arranged to drive the cannula subassembly to a deployed position on the skin of the patient along a path defining the preset angle with respect to the patient&#39;s skin. The cannula driver has a stabilizing base to engage the patient&#39;s skin and an actuator arranged to be acted upon in a direction substantially transverse to the stabilizing base for actuating the cannula driver. 
     The docking structure is generally cylindrically shaped and has a center axis substantially transverse to the base second surface. The cannula driver includes a needle carrying the cannula, and the cannula driver is arranged to translate the needle and cannula into the deployed position beneath the patient&#39;s skin. The cannula driver includes a drive element that drives the cannula subassembly to the deployed position with the base first surface adhered to the patient&#39;s skin and the needle and cannula beneath the patient&#39;s skin and at the preset angle with respect to the patient&#39;s skin. The drive element may include a spring. 
     The cannula driver may include a needle carrying the cannula. The cannula driver may be arranged to translate the needle and cannula from the cannula driver to the deployed position, and further arranged to withdraw the needle from the cannula and return the needle to the cannula driver leaving the cannula in the deployed position projecting from the base first surface beneath the patient&#39;s skin. The cannula driver may include an inner compartment and the cannula driver may be arranged to release the needle into the inner compartment after withdrawing the needle from the cannula. 
     The cannula driver may have a distal end arranged to engage the patient&#39;s skin and establish the path defining the preset angle with respect to the patient&#39;s skin. The cannula driver may include a drive element that withdraws the needle from the cannula and returns the needle to the cannula driver leaving the cannula in the deployed position beneath the patient&#39;s skin. The drive element may be a spring. 
     The cannula driver may include an actuator which, when acted upon, causes the cannula assembly to be driven to the deployed position and a protective cover overlying the actuator that precludes the actuator from being inadvertently acted upon. 
     The protective cover preferably is a break-away cap structure. 
     The docking structure may include an upper surface having a septum that is arranged to receive a needle of the source of liquid medicament. The docking structure may further have a locking structure that locks the source of liquid medicament and the docking structure together. The locking structure may be a releasable locking structure comprising a detent. The detent may take the form of a circumferential groove within the docking structure. 
     The docking structure may have a locking structure for releasably locking the cannula subassembly within the cannula driver. The locking structure may a detent formed by a circumferential groove within the docking structure. 
     In a still further embodiment, a cannula driver deploys a cannula subassembly in a deployed position on the skin of a patient. The driver comprises a carrier that translates the cannula subassembly along a path defining a preset angle of other than ninety degrees with respect to the patient&#39;s skin, a stabilizing base to engage the patient&#39;s skin, and an actuator arranged to be acted upon in a direction substantially transverse to the stabilizing base for actuating the cannula driver. 
     The cannula subassembly includes a base and a cannula projecting from the base at the preset angle. The carrier maintains the cannula base substantially parallel to the stabilizing base as the cannula subassembly is translated for deployment. 
     The carrier includes a needle that is received by the cannula and carries the cannula subassembly to the deployed position. A drive element acts upon the carrier to drive the cannula subassembly to the deployed position. The drive element may include a spring. 
     The carrier may include a needle that is received by the cannula and carries the cannula subassembly to the deployed position. The cannula driver may be further arranged to withdraw the needle from the cannula and return the needle to the cannula driver leaving the cannula in the deployed position projecting from the cannula subassembly base beneath the patient&#39;s skin. The cannula driver may include an inner compartment and the cannula driver may be arranged to release the needle into the inner compartment after withdrawing the needle from the cannula. 
     The driver may further include a drive element that withdraws the needle from the cannula and returns the needle to the cannula driver leaving the cannula in the deployed position beneath the patient&#39;s skin. The drive element may be a spring. 
     The cannula driver may include an actuator which, when acted upon, causes the cannula assembly to be driven to the deployed position and a protective cover overlying the actuator that precludes the actuator from being inadvertently acted upon. 
     The protective cover may be a break-away cap structure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with further features and advantages thereof, may best be understood by making reference to the following description taken in conjunction with the accompanying drawings, in the several figures of which like reference numerals identify identical elements, and wherein: 
         FIG. 1  is a top perspective view of an infusion assembly embodying the present invention; 
         FIG. 2  is bottom perspective view of the infusion assembly of  FIG. 1  embodying the present invention; 
         FIG. 3  is a cross-sectional side view to an enlarged scale of a cannula subassembly embodying the present invention; 
         FIG. 4  is a side view, with portions cut away, of a cannula subassembly driver embodying the present invention; 
         FIG. 5  is side view similar to  FIG. 4 , with portions cut away, of the cannula subassembly driver of  FIG. 4  in an initial pre-actuation stage of driving a cannula subassembly for deployment on and beneath a patient&#39;s skin; 
         FIG. 6  is another side view, with portions cut away, of the driver of  FIG. 4  in a second stage of driving a cannula subassembly for deployment on and beneath a patient&#39;s skin in accordance with an embodiment of the present invention; 
         FIG. 7  is another side view, with portions cut away, of the driver of  FIG. 4  in a third stage of driving a cannula subassembly for deployment on and beneath a patient&#39;s skin in accordance with an embodiment of the present invention; 
         FIG. 8  is another side view, with portions cut away, of the driver of  FIG. 4  in a final stage after driving and deploying a cannula subassembly on and beneath a patient&#39;s skin in accordance with an embodiment of the present invention; 
         FIG. 9  is a bottom view of the driver of  FIG. 4  illustrating the elements thereof in the pre-actuation stage; 
         FIG. 10  is a bottom view of the driver of  FIG. 4  after the driver has been initially actuated; 
         FIG. 11  is a bottom view of the driver of  FIG. 4  just prior to the cannula subassembly reaching a fully deployed position; 
         FIG. 12  is a bottom view of the driver of  FIG. 4  after the cannula subassembly has been deployed and the cannula needle has been withdrawn from the cannula subassembly back into the driver for safe sharps disposal; 
         FIG. 13  is a simplified schematic representation of an infusion assembly embodying further aspects of the present invention to illustrate automatic priming thereof; 
         FIG. 14  is a partial view of the source subassembly of  FIG. 13  illustrating the priming in process; 
         FIG. 15  is a partial view of the source subassembly of  FIG. 13  illustrating the completion of the priming process; 
         FIG. 16  is a partial perspective view with portions cut away of an infusion assembly embodying the present invention showing a cannula subassembly and a source subassembly prior to docking in accordance with an embodiment of the invention; 
         FIG. 17  is a partial perspective view with portions cut away of the cannula subassembly and a source subassembly of  FIG. 16  prior to docking according to an embodiment of the invention; 
         FIG. 18  is a partial perspective view with portions cut away of the cannula subassembly and a source subassembly of  FIG. 16  after docking according to an embodiment of the invention; and 
         FIG. 19  is a perspective view with portions cut away of the infusion assembly of  FIG. 16  showing the liquid medicament flow path established upon the cannula subassembly and source subassembly being docked in accordance with an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to  FIGS. 1 and 2 , they show an infusion assembly  20  embodying the present invention. The infusion assembly is arranged to be worn on the skin of a patient and is preferably disposable after use. To that end, the infusion assembly generally includes a cannula subassembly  22  and a source subassembly  24 . The cannula subassembly  22  and source subassembly  24  are initially separate units that may be docked together to form the infusion assembly  20 . Each is deployed by the patient separately, first the cannula subassembly  22  and then the source subassembly  24 . 
     As may be noted, the cannula subassembly  22  includes a cannula  26  projecting from a first or bottom surface  28  so that when the cannula subassembly is deployed on the patient&#39;s skin, the cannula projects to beneath the skin of the patient. This supports the delivery of liquid medicament, such as insulin, to the patient from the cannula  26 . The surface includes an adhesive coated portion  30  to permit the cannula subassembly  22  to adhere to the patient&#39;s skin. 
     The source subassembly  24  similarly includes an adhesive coated bottom surface  32 . This permits the source subassembly  24  to adhere to the patient&#39;s skin. It is to be particularly noted that, in accordance with one aspect of the present invention, the adhesive coating  30  of the cannula subassembly  22  is separate and independent from the adhesive coating  32  of the source subassembly  24 . Hence, each may be independently adhered to the patient&#39;s skin. 
     As may be more readily seen in  FIG. 1 , the source subassembly  24  includes a pair of actuator buttons  40  and  42 . When a bolus of insulin is desired, the buttons are depressed concurrently. If the buttons are not depressed concurrently, the bolus will not be delivered. This prevents accidental actuation of the device. As will be seen subsequently, the source subassembly  24  includes a reservoir that may be filled with the liquid medicament, such as insulin, by the patient before the source subassembly  24  is docked with the cannula subassembly  22 . As the source subassembly  24  and cannula subassembly  22  are docked together, the cannula  26  is primed with insulin and a fluid path from the reservoir of the source subassembly to the cannula  26  is established. Concurrent depression of the buttons  40  and  42  then causes the dose of insulin to be pumped from the reservoir to and out of the cannula  26 . A bolus may comprise a plurality of such doses. 
     The source subassembly  24  further includes a port  44  within its housing  34 . The port  44  communicates with the cannula  26  as will be seen herein after. This permits injections of insulin or another liquid medicament from a separate external source to be introduced into the port  44  and administered to the patient through the cannula  26 . 
       FIG. 3  is a side view in cross section of the cannula subassembly  22 . The cannula subassembly includes a base  50  and a docking structure  52 . The base defines the first surface  28  and a second surface  54 . The first surface  28  and the second surface  54  are parallel to each other. The docking structure comprises a cylindrical structure  56  having a center axis  58 . The center axis extends substantially transverse to the second surface  54 . Hence, a source subassembly received on the docking structure  52  in any radial orientation. The docking structure includes a locking structure in the form of a detent  60  and more particularly in the form of a circumferential groove to releasably receive the source subassembly  24 . As will be seen subsequently, the source subassembly  24  includes a complementary projection to be received within the groove  60 . The groove  60 , as will be seen subsequently, also enables the cannula subassembly to be releasably held within a deployment driver as it is translated to a deployed position on the patient. 
     The docking structure  52  also includes a chamber  62  communicating with the cannula  26 . A septum  64  overlies the chamber  62  within a top surface flange  66 . The septum may be pierced by a needle carried by the source subassembly to couple the source subassembly reservoir to the cannula when the source subassembly is docked with the docking structure  52 . It may also be pierced by the needle of a syringe to administer insulin or other liquid medicament from a separate external source. 
       FIGS. 4-12  illustrate a driver  70  and its sequential operation for deploying the cannula subassembly  22  according to an embodiment of the invention. The driver  70  includes an actuator  72 , a release mechanism  74 , and a drive mechanism  76 . The forging are housed in a housing  78  that includes a substantial stabilizing surface  80  arranged to contact a patient&#39;s skin. 
     The actuator  72  comprises a button  82  that is loaded by a spring  84 . A protective cover  86  overlies the button  84  to form a lock-out structure to prevent accidental actuation of the driver. The cover  86  is breakable along a frangible connection  88  to permit the cover  86  to be readily removed when use of the driver  70  is desired. The button has an extension  90  arranged to engage a pivotal arm  92  of the release mechanism  74 . In doing so, the button  82  and its extension  90  are caused to translate in a direction substantially transverse to the stabilizing surface. This provides better control of the driver actuation for the user. 
     The release mechanism is biased by a spring  94 . When the driver is to be actuated, the extension  90  engages the arm  92  and pushes the arm  92  downward. This causes a release pin  96  to be raised and disengaged form the drive mechanism  76 . 
     More specifically, the drive mechanism  76  includes a carrier  100  that moves within a tubular track  102 . The carrier is propelled toward the patient&#39;s skin buy a first spring  104 . The carrier includes a circumferential bead  106  that is releasably received by the circumferential groove  60  of the cannula subassembly  22 . The tubular track  102  directs the carrier along a path that defines an angle with respect to the stabilizing surface that is substantially equal to the non-perpendicular angle theta defined by the cannula  26  and the patient&#39;s skin. This maintains the first surface  28  of the cannula subassembly substantially parallel to the patient&#39;s skin throughout the cannula subassembly deployment. 
     During the deployment of the cannula subassembly  22 , a cannula needle  108  is received by the cannula  26 . The needle  108  is carried by a needle holder  110 . As will be seen subsequently, when the cannula subassembly  22  has reached its deployed position, the needle holder  110 , and hence the needle, are drawn or pushed back into the driver  70  by a second drive spring  112 . The needle  108  and holder  110  are then caused to reside within a chamber to enable safe sharps disposal of the needle. Also, since the needle is disengaged from the drive mechanism, reuse of the driver is precluded. 
       FIGS. 5 and 8  show the state of the driver  70  just prior to actuation. In  FIG. 5  it will be noted that the protective cover has been removed from the actuator button  82 . The needle holder  108  has a pair of legs that abut a circumferential flange  122  of the carrier  100 . Hence, when the carrier moves towards the patient&#39;s skin, it will push the needle holder  108  and the cannula subassembly  22  together. 
     In  FIG. 6  it may be seen that the actuator button  82  has been depressed causing it to engage pivotal arm  92 . Arm  92  pivots to raise the release pin  94  against the force of spring  94 . The carrier is now free to move towards the patient&#39;s skin under the force of the spring  104 . 
       FIG. 10  shows the carrier  100  on its way towards the patient&#39;s skin. It may be noted that the carrier  100  is pushing the needle holder  110 . When the carrier  100  begins to reach the end of its travel, the legs  120  of the needle holder engage surfaces  122  of the driver housing  72 . These surfaces  122  force the legs  120  inwardly. 
     When the carrier has reached the end of its travel as shown in  FIG. 7 , the cannula subassembly is deployed on the patient&#39;s skin  130  and the cannula  26  extends beneath the skin at an angle theta with respect thereto. The legs  120  are now suddenly deflected sufficiently inwardly to clear the inner diameter  124  of the inner chamber  126  of the carrier  100  and the needle holder  110  is pushed by the spring  112  into the chamber  126 . The needle  108  and its holder  110  are now free to float within the chamber  126  as shown in  FIGS. 8 and 12 . The driver may now be removed from the docking structure  56  of the cannula subassembly  22 . This may be accomplished by releasing the circumferential bead  106  from the circumferential groove  60  of the docking structure  56  of the cannula subassembly  22 . 
       FIG. 13  is a simplified schematic representation of an infusion assembly  220  embodying further aspects of the present invention. The infusion assembly  220  generally includes a cannula subassembly  222  and a source subassembly  224 . The cannula subassembly  222  and source subassembly  224  are initially separate units that may be docked together to form the infusion assembly  220 . Each is deployed by the patient separately, first the cannula subassembly  222  and then the source subassembly  224 . 
     The cannula subassembly  222  includes a cannula  226  projecting from a first or bottom surface  228  so that when the cannula subassembly is deployed on the patient&#39;s skin, the cannula projects to beneath the skin of the patient. This supports the delivery of liquid medicament, such as insulin, to the patient from the cannula  226 . The surface  228  includes an adhesive coating to permit the cannula subassembly  222  to adhere to the patient&#39;s skin. As in the previous embodiment, the cannula subassembly  222  includes a cylindrical docking structure  256 . The docking structure  256  is covered by a septum  264  and includes a rim surface  257 . 
     The source subassembly includes a reservoir  230 , a one-way valve  232 , a piston pump  234 , another one-way valve  236 , a flexible conduit  238 , and a needle  240 . The source subassembly  224  further includes a housing  242  which has a substantially cylindrical docking port  244  that is dimensioned to receive the docking structure  256  therein. The flexible conduit  238  includes a primer  237 . The primer  237  includes a reservoir  239  within the conduit  238  which is filled with the insulin prior to the docking of the source subassembly  224  and the cannula subassembly  222 . The reservoir  239  is sized to hold the volume of insulin required to fill the needle  240 , the cannula  226 , and the conduit between the reservoir  239  and the needle  240  when the cannula subassembly  222  and the source subassembly  224  are brought together. This serves to prime the infusion assembly  220  for eliminating air bubbles from the insulin passageway. 
     More specifically, as may be noted in  FIG. 14 , as the docking structure  256  of the cannula subassembly  222  is brought into engagement with the docking port  244  of the source subassembly  224 , the rim  257  of the docking structure  256  engages the reservoir  239  and collapses it. This forces the insulin therein to flow through the needle  240 . Also, as the docking port  244  receives the docking structure  256 , the needle  240  penetrates the septum  264  to be in fluid communication with the cannula  226 . Hence, during the docking of the cannula subassembly  222  and the source subassembly  224 , The flow path to the cannula  226  from the reservoir  230  is established and the flow path to the cannula tip  227  is primed. 
       FIGS. 16-18 , show the docking of the cannula subassembly  22  and the source subassembly  24 . As may be seen in  FIG. 16 , the cannula subassembly  22  is aligned with the substantially cylindrical docking port  344  of the source subassembly  24 . As the cannula subassembly  22  enters the docking port  344 , the needle  340  of the source subassembly  24  will pierce the septum  64  of the cannula subassembly  22  before the cylindrical docking structure  56  engages the priming reservoir  339 . Then, as seen in  FIG. 17 , the cylindrical docking structure  56  begins to collapse the priming reservoir  339  and the circumferential groove  60  of the cannula subassembly  22  begins to be received by a complimentary circumferential band  346  of within the docking port  344  of the source subassembly  24 . Lastly, as may be seen in  FIG. 18 , when the cylindrical docking structure  56  of the cannula subassembly  22  is fully within the cylindrical docking port  344  of the source subassembly  24 , the priming reservoir is fully compressed and the needle  340  has established fluid communication with the cannula  26 . Also, the cannula subassembly  22  is locked within the source subassembly  24  by the band  346  having been fully received within the circumferential groove  60 .  FIG. 19  shows the fluid path  25  established by the cannula subassembly  22  having been fully received in the source subassembly  24  to form the infusion assembly  20 . The fluid path extends from the infusion assembly reservoir  29  to the tip  27  of the cannula  22 . 
     While particular embodiments of the present invention have been shown and described, modifications may be made, and it is therefore intended in the appended claims to cover all such changes and modifications which fall within the true spirit and scope of the invention as defined by those claims.
An infusion assembly comprises a cannula subassembly and a source subassembly. The cannula subassembly includes a substantially planar base, a cannula projecting from the base so as to be beneath the patient's skin when the subassembly is deployed, and a generally cylindrical docking structure having a center axis substantially perpendicular to the base. A liquid medicament is dispensed from the cannula. The source subassembly is arranged to dock with the docking structure and includes a supply of liquid medicament that couples to the cannula upon the source subassembly docking with the cannula subassembly. The source subassembly also includes a primer that automatically primes the insulin fluid path to the cannula tip when the subassemblies are joined.