Medicine dispensing device
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.
1. A wearable medicine dispensing device, comprising:
a housing that defines a cavity to receive a separate medicine-filled container such that an output end of the container is positioned away from a piston rod, wherein the piston rod is arranged in the housing and movable in a forward direction toward the separate medicine-filled container when the separate medicine-filled container is received in the cavity;
a drive mechanism arranged in the housing and configured to advance the piston rod in the forward direction, the drive mechanism comprising a pawl and a ratchet wheel having teeth, the pawl positioned to engage at least one of the teeth of the ratchet wheel, wherein the pawl reciprocates between first and second positions to incrementally rotate the ratchet wheel, wherein rotation of the ratchet wheel in a drive direction drives a linear advancement of the piston rod;
a reversible motor coupled to the drive mechanism such that rotation of the reversible motor urges the pawl toward one of the first and second positions; and
a battery electrically connected to the reversible motor so as to provide electrical power to rotate the reversible motor in a first direction and in a second reverse direction,
wherein a motor rotation cycle, which includes one or more full rotations of the reversible motor in a first rotational direction and one or more full rotations of the reversible motor in a second reverse rotational direction, causes the ratchet wheel to be advanced by one tooth corresponding to displacement of the pawl between the first and second positions and incrementally advance the piston rod in the forward direction toward the separate medicine-filled container in the cavity of the housing.
2. The wearable dispensing device of claim 1 , wherein the drive mechanism limits advancement of the piston rod to a single increment in response to a short circuit of the reversible motor.
3. The wearable medicine dispensing device of claim 1 , wherein repeated motor rotation cycles, each of which comprising one or more full rotations of the reversible motor in the first rotational direction and one or more full rotations of the reversible motor in the second reverse rotational direction, cause the piston rod to incrementally advance in the forward direction toward the separate medicine-filled container in the cavity of the housing in a series of longitudinally forward increments.
4. The wearable medicine dispensing device of claim 1 , wherein the drive mechanism prevents dispensation of the medicine in the event of continuous rotation of the reversible motor.
5. The wearable medicine dispensing device of claim 4 , wherein the drive mechanism prevents dispensation of the medicine in the event of continuous rotation of the reversible motor so as to provide a fail-safe protection against over-dosage of medicine.
6. The wearable medicine dispensing device of claim 1 , further comprising at least two gears coupled between the reversible motor and the pawl.
7. The wearable medicine dispensing device of claim 6 , further comprising a rigid plate member coupled between the at least two gears and the pawl.
8. The wearable medicine dispensing device of claim 6 , wherein one or more full rotations of the rotational motor causes the pawl to pivot about an axis.
9. The wearable medicine dispensing device of claim 1 , further comprising a control circuit device to repeatedly reverse the direction of rotation of the rotational motor.
10. The wearable medicine dispensing device of claim 9 , further comprises a sensor that causes the rotation of the motor to be reversed from the first direction to the second reverse direction.
11. The wearable medicine dispensing device of claim 1 , wherein the ratchet wheel is locked from rotation in a direction opposite to the drive direction.
12. The wearable medicine dispensing device of claim 1 , wherein the ratchet wheel directly engages with the piston rod.
13. The wearable medicine dispensing device of claim 12 , wherein the ratchet wheel comprises an internal thread that engages with an outward thread of the piston rod.
14. The wearable medicine dispensing device of claim 13 , wherein the piston rod comprises a flexible piston rod having rod segments hinged together and outwardly threaded, wherein at least a portion of the flexible piston rod extends longitudinally in a curved configuration inside the housing.
15. The wearable medicine dispensing device of claim 1 , wherein the pawl reciprocates between a retracted position and an engaged position to incrementally rotate the ratchet wheel.
16. The wearable medicine dispensing device of claim 1 , further comprising a linearly displaceable plate coupled to the pawl and coupled to the reversible motor.
17. The wearable medicine dispenser device of claim 16 , wherein one or more full rotations of the reversible motor causes the linearly displaceable plate to act upon the pawl.
18. A method of dispensing a medicine from the wearable medicine dispensing device of claim 1 , the method comprising:
rotating the reversible motor according to a motor rotation cycle that includes one or more full rotations of the reversible motor in the first direction and one or more full rotations of the reversible motor in the second reverse direction, wherein the rotation of the reversible motor according to the motor rotation cycle urges the drive mechanism to advance the piston rod in a longitudinally forward increment toward the medicine-filled container arranged in the wearable medicine dispensing device; and
dispensing at least a portion of the medicine out of the medicine-filled container arranged in the wearable medicine dispensing device in response to movement of the piston rod in the longitudinally forward increment.