Abstract:
Some embodiments of a wearable, disposable medicine dispensing device may include a piston rod that is advanced to dispense medicine from the device. A rotational motor may be coupled to a drive mechanism so as to carry out a certain number of revolutions and thereby displace the piston rod by a desired distance. Such a device can be used in a method of dispensing liquid medicine.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 12/767,570 filed on Apr. 26, 2010, which is a continuation of U.S. patent application Ser. No. 10/591,190 filed on Aug. 31, 2006, which is a national stage application under 35 U.S.C. § 371 that claims the benefit of PCT/DK2006/000195 (published as WO2006/105794) filed on Apr. 6, 2006, which claims priority to the following Denmark patent applications: serial no. PA 2005 00483 filed on Apr. 6, 2005, serial no. PA 2005 00542 filed on Apr. 14, 2005, and serial no. PA 2005 00817 filed on Jun. 3, 2005. The entire contents of these prior applications are incorporated herein by reference. 
     
    
     SUMMARY 
       [0002]    The present invention relates to a method of dispensing liquid medicine comprising the steps of providing a wearable, disposable dispensing device comprising a syringe having a cylinder and a plunger displaceable in said syringe cylinder for pressing medicine out of said syringe cylinder and a drive mechanism connected to said plunger for displacing said plunger in said cylinder, and an electrical motor connected to a battery and to said drive mechanism for providing a rotary force to said driving mechanism for displacing said plunger, displacing said plunger a certain distance in connection with a cycle of said driving mechanism. 
         [0003]    Methods of this type are known, wherein the electrical motor is controlled by a control means so as to carry out a certain number of revolutions for each cycle corresponding to the desired distance of displacement of the plunger. 
         [0004]    In connection with such methods it is important that no more than the predetermined amount of medicine be dispensed per cycle as otherwise life threatening dosages may be dispensed. 
         [0005]    When utilizing an electrical motor, a short circuit can entail that the motor does not stop after the predetermined number of revolutions or that the motor starts by itself. 
         [0006]    Security means have been suggested to ensure that the predetermined dosage is not exceeded, for instance monitoring the amount of liquid dispensed per cycle or monitoring the displacement distance of the plunger or the amount of revolutions of the motor per cycle with interruption means being activated if the monitored elements exceed a certain value. 
         [0007]    There exists a need for a simple and fail-safe method to avoid over-dosage of medicine. One main object of the invention is to meet this need. 
         [0008]    According to the invention this object is achieved by the cycle comprising rotating said electrical motor in a first direction of rotation and subsequently rotating said electrical motor in the opposite direction of rotation. 
         [0009]    Hereby, any short-circuit of the motor will not entail continued rotation of the motor in one direction with ensuing continued dispensing of medicine. 
         [0010]    The invention furthermore relates to a wearable, disposable medicine dispensing device comprising:
       a syringe having cylinder and a plunger displaceable in the syringe cylinder for pressing medicine out of said syringe cylinder,   a drive mechanism connected to said plunger for displacing said plunger in said cylinder, and   an electrical motor connected to a battery and to said drive mechanism for providing a rotary force to said driving mechanism for displacing said plunger, and   control means adapted for repeatedly reversing the direction of rotation of said electrical motor.       
 
         [0015]    In a further aspect, the present invention relates to an actuator comprising:
       a rotational motor.   one or more elongate, flexible elements such as a string, a filament, a strip, a ribbon and combinations thereof, said one or more elements being attached to said motor for rotation thereby and to a displaceable body, such that rotation of said motor twists said one or more elements and shortens the overall length thereof so that said displaceable body is displaced by the shortened element or elements.       
 
         [0018]    Such an actuator according to the invention may be used in connection with medicine dispensing devices, but also in any application where a rotational force or movement is to be utilized to displace a body. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0019]    In the following the invention will be described more in detail in connection with two embodiments shown, solely by way of example, in the accompanying drawings, where 
           [0020]      FIG. 1  shows a first embodiment of a device according to the invention seen in perspective and with the top part of the housing removed, 
           [0021]      FIG. 2  shows a perspective view of the drive mechanism of the device according to the invention in  FIG. 1 , 
           [0022]      FIG. 3  is an exploded view of some of the drive mechanism elements of the device in  FIG. 1 , and 
           [0023]      FIGS. 4 and 5  are views corresponding to  FIG. 2  with the drive mechanism in other positions, and 
           [0024]      FIGS. 6-9  are views of a second embodiment of the device according to the invention corresponding to  FIGS. 1 ,  2 ,  4  and  5 , respectively. 
           [0025]      FIGS. 10-14  show a perspective view of a third embodiment of the device according to the invention in different sequential states during a first half cycle during rotation of the electrical motor in a first direction of rotation, 
           [0026]      FIGS. 15   a, b  and  c  are views of some of the drive mechanism elements of the device in  FIGS. 10-14  in different states during the cycle. 
           [0027]      FIG. 16 . is a schematic perspective view of a first embodiment of an actuator according to the invention, and 
           [0028]      FIGS. 17   a - b  very schematically show a second embodiment of an actuator according to the invention at two different phases of an actuation cycle. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]    Referring now to  FIGS. 1-5 , a wearable disposable dispensing device for medicine referred to generally by the numeral  1  and of the type described in WO 2004/041330 and WO 2004/056412, the disclosure of which is hereby incorporated herein by reference, comprises a housing  2 , where only the bottom half is shown for the sake of clarity, a cylindrical medicine container or carpule  3  having at one end a silicone body for receiving a catheter for dispensing medicine from the interior of the carpule to a human body and being open at the opposite end to receive a flexible piston rod  5  for displacing an internal not shown plunger or piston in the carpule  3  for forcing medicine out through a catheter needle assembly connected to the silicone body  4 . 
         [0030]    The flexible piston  5  is composed of segments hinged together and outwardly threaded guided by a rail  6  received in recesses in each of the segments of the rod  5 . The not shown outward threads of the segments of the flexible piston rod  5  engage in a thread  8  of ratchet wheel  7  having teeth  9  along the periphery thereof. An electrical motor  10  electrically connected to a battery  11  and control means  12  is provided with a gear  13  meshing with a gear  14  attached to an outwardly threaded spindle or shaft  15  received in an inwardly threaded nut  16  attached a plate  17  provided with two slits  18  and  19 , extending parallel to the axis of said spindle  15  and a third slit  20 , extending at an angle to said axis. Two fixedly arranged pins  21  and  22  are received in the slits  18  and  19 , respectively such that the pins serve as guides to the to and fro displacement of the plate  17  by means of the spindle  15  when the electrical motor  10  rotates first in one directional rotation and thereafter in the opposite directional rotation. 
         [0031]    A protuberance  23  is arranged on the plate  17  to co-operate with two end stop contacts  24  and  25  electrically connected to the control means  12  for reversing the direction of rotation of the electrical motor when the protuberance  23  contacts one of the end stop contacts  24  or  25 . A pawl  26  is attached to a pivotable elongated body  27  having a pin  28  for being received in the oblique slit  20  and a hole  29  for receiving the pin  21  such that the body  27  is pivotable around the pin  21 . A ratchet  30  is fixedly attached to the housing  2  by means of a pin  31  and is located so as to engage the teeth  9  of the ratchet wheel  7 . The pawl  26  is displaceable from a retracted position where it does not engage the teeth  9  of the ratchet wheel  7  and in an engaged position in which it engages the teeth of the ratchet wheel and rotates the ratchet wheel in a clockwise direction. 
         [0032]    The displacement of the pawl  26  between the two positions indicated above takes place by the linear displacement of the plate  17 . When the plate  17  is displaced in the direction from the end stop contact  24  to the end stop contact  25 , the oblique slit  20  urges the pin  28  of the elongated body  27  in a direction  10  away from the carpule  3  such that the elongated body  27  pivots around the pin  21  in a clockwise direction, whereby the pawl  26  is moved in towards its retracted position relative to the ratchet wheel  7 . When the protuberance  23  on the plate  17  contacts the end stop contact  25 , the directional rotation of the motor  10  is reversed and the plate  17  is displaced in the direction from the end stop contact  25  towards the end stop contact  24 , whereby the oblique slit  20  forces the pin  28  towards the carpule  3 , whereby the elongated body  27  is forced to rotate in a counterclockwise direction whereby the pawl  26  is brought into contact with one of the teeth  9  of the ratchet wheel and rotates the ratchet wheel in a clockwise direction, while the ratchet rides over one of the other teeth  9  for locking the ratchet wheel against rotation in the counterclockwise direction. 
         [0033]    Thus, during one cycle of rotation in one direction and the opposite direction of the electrical motor  10 , the ratchet wheel  7  will be advanced by one tooth corresponding to one displacement of the pawl  26  from the retracted position thereof to the engaged position thereof. 
         [0034]    Referring now to  FIGS. 6-9 , in this embodiment a coil spring  40  is attached to a pin  41  fixedly attached to the housing  2  and a pin  42  fixedly attached to the plate  17 . 
         [0035]    When the plate  17  is moved in the direction from end contact  24  towards the end contact  25 , the spring  40  is in tension, and when the plate  17  moves back in a direction from the end stop contact  25  towards the end stop contact  24  after reversion of the direction of rotation of the motor  10 , the spring  40  will be relaxed and exert a force in the same direction as the motor  10  on the plate  17  and thus reinforcing the force available to rotate the ratchet wheel  7 . 
         [0036]    Referring now to  FIGS. 10-15 , the electrical motor  10  is electrically connected to a battery and control means and the axle of the motor is connected to a pair of twisted strings  35  or a band or similar device, which reduces its length when twisted and increases its length when untwisted, said length variation being provided by the rotation of the motor, i.e. the device is connected to the rotating axle of the motor at one end and connected to a pivotable body  78  at the opposite end. The pivotable body is provided with an extension  78   a  comprising a pawl  74  arranged to engage the teeth  9  on the ratchet wheel  7 , as indicated in  FIGS. 15   a ,  15   b ,  15   c , whereby the pivoting of the pivotable body  78  provides a rotation of the ratchet wheel  7 . A second pawl mechanism  72 ,  84  is provided to prevent rotation of the ratchet wheel  7  in the opposite direction, again as shown in  FIGS. 15   a - 15   c.    
         [0037]    The displacement of the pawl  74  between the two positions indicated in  FIGS. 15   a  and  15   b  is provided by the reduction of the length of the twisted strings  35  by rotation of the motor and the displacement in the opposite direction is provided by the spring  40  during extension of the twisted strings  35  provided by rotation of the motor in the opposite direction, whereafter further rotation in this direction again reduces the length of the twisted strings  35 , whereby a complete cycle of rotation in one direction of the motor provides a movement of the pivotable body from the position shown in  FIG. 15   a  to the position shown in  FIG. 15   b  and back to the position shown in  FIG. 15   a , this movement being provided by the twisted strings  35  being untwisted and twisted in the opposite direction during rotation of the motor in one direction. Thus, the rotation of the motor in one direction of rotation provides a full stroke for the pivotable body and thus the pawl mechanism moving the ratchet wheel one step forward and the following rotation of the motor in an opposite direction of rotation provides a further full stroke of the pivotable body and the pawl mechanism. 
         [0038]    Thus, during one cycle of rotation in one direction and the opposite direction of the electrical motor  10 , the ratchet wheel  7  will be advanced by two teeth corresponding to two displacements of the pawl  74 . The pivotable body  78  comprises a protuberance  78   a  which co-operates with two end stop contacts  85   a  and  85   b  electrically connected to the control means for controlling the reversal of the direction of rotation of the electrical motor when the protuberance  78   a  contacts the end stop contact  85   a.  Due to the fact that the twisted strings  35  can only provide a pulling force on the pivotable body  78 , a spring  40  is connected to the pivotable body to provide the movement in the direction shown by the arrow in  FIG. 10 . 
         [0039]    In the embodiment shown in the figures spring  40  is a coil spring, however, other types of springs, such as a rod spring could be provided for this purpose. 
         [0040]    Referring now to  FIG. 16 , an actuator according to the invention is referred to generally by the numeral  50  and is identical to the actuator shown in  FIGS. 10-14 . This actuator may be employed for any use requiring transformation of a rotation to a linear movement or a rotational force to a linear force. 
         [0041]    A rotation motor  51  is attached to a pair of elongate, flexible elements such as strings or filaments  52  by means of a rotational body  53  that may or may not function as a fly wheel. The elements  52  are attached to a pin  54  on a pivotable plate. Rotation of the motor in the direction R 1  will twist the strings  52  such that the length thereof is shortened until the pin  54  is displaced linearly in the direction R 2  whereby the plate  55  is rotated around pivot  56  in the direction R 3 . A tension spring  57  is attached to plate  55  at pin  58  and to a not shown frame at pin  59 . 
         [0042]    Rotation of the plate  55  will expand the spring  57  in the direction R 4  against the spring force thereof. 
         [0043]    Rotation of the motor  51  in the direction opposite R 1  will at first untwist the elements  52  whereby the length thereof becomes larger with the consequence that the spring  57  rotates the plate  55  in the direction opposite R 3 . 
         [0044]    Further rotation of the motor  51  in the direction opposite R 1  will twist the elements  52  again an eventually exert a force on said pin  54  in direction R 2  again, the direction of rotation being subsequently reversed again and the cycle starts anew. 
         [0045]    In case, a smaller interval is desired between each turn of the plate  55  in the direction R 3 , the motor  51  may reverse direction of rotation as soon the elements  52  have become untwisted to an extent that the spring  57  has pivoted the plate a certain distance in the direction opposite R 3 . 
         [0046]    Reference is now made to  FIGS. 17   a - 17   b , where a motor  51  is attached to both opposed ends of an elongate, flexible element such as a string or filament  52  by means of a rotational body  53  that may or may not function as a fly wheel. The element  52  forms a loop  60  within which are located two bodies  61  and  62 . 
         [0047]    The body  61  is displaceable along a groove  63  in which a pin  64  of the body is slideably received. A spring  65  is attached to the displaceable body  61  such that displacement of said body  61  in the direction R 5  takes place against the biasing force exerted by the spring  65 . 
         [0048]    The other body  62  is fixedly arranged such that when twisting of the element  52  by rotation of the motor  51  takes place the loop  60  is reduced in size as seen in  FIG. 17   b  and the displaceable body  61  is forced towards the fixed body  62  along the groove  63  and against the spring force of the spring  65 . 
         [0049]    When the rotational direction of the motor is reversed so that it rotates in the direction R 7 , the element  52  will be untwisted, the loop  60  will enlarge and the spring  65  will displace the body in the direction R 6 . 
         [0050]    Although the groove is shown extending substantially linearly, it may obviously be curved and extend at different angles to the axis of the motor. 
         [0051]    The body  61  may be attached to a multitude of different driving or transmission mechanisms, for example the ratchet and pawl mechanisms shown in  FIGS. 1-9 . 
         [0052]    A displaceable body should be taken to mean any body that can change position either by linear motion, curved motion, rotative motion, etc. and any combination thereof under the influence of a force applied to a point on or in said body. 
         [0053]    Displacement should likewise be taken to mean any change in position resulting from linear motion, curved motion, rotative motion, etc. and any combination thereof.