Injection device with torsion spring and rotatable display

• US 20090054839A1
• Filed: 10/20/2005
• Published: 02/26/2009
• Est. Priority Date: 10/21/2004
• Status: Active Grant

• Current Assignee: Novo Nordisk A/S
• Original Assignee: Novo Nordisk A/S
• Inventors: Markussen, Tom Hede, Enggaard, Christian Peter, Moller, Claus Schmidt
• Granted Patent: US 8,357,120 B2
• Time in Patent Office: Days
• US Class Current: 604/135
• CPC Class Codes: A61M 2005/202 cocking means, e.g. to bias the main drive spring of an injector
• CPC Class Codes: A61M 2005/3125 specific display means, e.g. to indicate dose setting
• CPC Class Codes: A61M 5/14566 with a replaceable reservoir for receiving a piston rod of the pump
• CPC Class Codes: A61M 5/20 Automatic syringes, e.g. with automatically actuated piston rod, with automatic needle injection, filling automatically A61M5/142 , A61M5/46 take precedence; hypodermic projectiles F42B12/54
• CPC Class Codes: A61M 5/31535 Means improving security or handling thereof, e.g. blocking means, means preventing insufficient dosing, means allowing correction of overset dose
• CPC Class Codes: A61M 5/3155 by rotational movement of dose setting member, e.g. during setting or filling of a syringe
• CPC Class Codes: A61M 5/31553 without axial movement of dose setting member
• CPC Class Codes: A61M 5/31556 Accuracy improving means
• CPC Class Codes: A61M 5/31583 based on rotational translation, i.e. movement of piston rod is caused by relative rotation between the user activated actuator and the piston rod
• CPC Class Codes: A61M 5/31593 Multi-dose, i.e. individually set dose repeatedly administered from the same medicament reservoir

Abstract

The present invention relates to an injection device comprising a torsion spring operatively connected to a dose setting member being adapted to set a dose to be ejected from the injection device. A rotatably mounted display member adapted to display the dose to be ejected in accordance with a setting of the dose setting member is also provided. The rotatably mounted display member is adapted to be rotated over an angle corresponding to at least one revolution of the display member. The display member may be implemented as a dose indicator barrel having numerals arranged along a helical path on an outer surface thereof, or alternatively, as a counting device having two or more display wheels having numerals arranged on an outer surface thereof.

Claims

1. An injection device comprising

a torsion spring (12) operatively connected to a dose setting member (1), the dose setting member (1) being adapted to set a dose to be ejected from the injection device, and

a rotatably mounted display member adapted to display the dose to be ejected from the injection device in accordance with a setting of the dose setting member (1), the rotatably mounted display member being rotatable over an angle corresponding to at least one revolution of the display member.

2. An injection device according to claim 1, wherein the display member is adapted to be moved between two end positions, said two end positions defining an operation range of the display member, said operation range being associated with a substantially linear working range of the torsion spring.

3. An injection device according to claim 1, wherein the display member comprises a dose indicator barrel (9) having numerals arranged along a helical path on an outer surface thereof.

4. An injection device according to claim 1, wherein the display member comprises a counting device having two or more display wheels having numerals arranged on an outer surface thereof.

5. An injection device according to claim 2, further comprising

a housing (5),

a piston rod (2) having a threaded outer surface with a drive track (7) arranged in a longitudinal direction of said outer surface,

wherein the dose setting member (1) is rotatably mounted and defines a passage for the piston rod (2), the dose setting member (1) further having a guiding track (11) arranged on an inner surface thereof,

a rotatable drive member (6) being adapted to at least partly engage with at least part of the drive track (7) of the piston rod (2) so as to drive the piston rod,

wherein the dose indicator barrel (9) has a part engaging at least part of the guiding track (11) of the dose setting member (1), the dose setting member (1) and the dose indicator barrel (9) being movable in relation to each other, the dose indicator barrel (9) further having a threaded outer surface (8) cooperating with a threaded inner portion (10) of the housing (5) whereby the dose indicator barrel (9) undergoes a combined translational and rotational movement in relation to the housing (5) upon rotation of the dose setting member (1), and

wherein the injection device has a threaded portion (3) cooperating with the threaded outer surface of the piston rod (2) so that rotation of the piston rod (2) relative to the housing (5) results in a longitudinal movement of the piston rod (2).

6. An injection device according to claim 2, further comprising

a housing (5),

a piston rod (2) having a threaded outer surface with a track (7) arranged in a longitudinal direction of said outer surface,

wherein the dose setting member (1) is rotatably mounted and defines a passage for the piston rod (2), the dose setting member (1) further having a guiding track (11) arranged on an inner surface thereof,

a rotatable drive member (6) having a threaded portion cooperating with at least part of the threaded outer surface of the piston rod (2),

wherein the dose indicator barrel (9) has a part engaging at least part of the guiding track (11) of the dose setting member (1), the dose setting member (1) and the dose indicator barrel (9) being movable in relation to each other, the dose indicator barrel (9) further having a threaded outer surface (8) cooperating with a threaded inner portion (10) of the housing (5) whereby the dose indicator barrel (9) undergoes a combined translational and rotational movement in relation to the housing (5) upon rotation of the dose setting member (1), and

wherein the injection device has a portion at least partly engaging the track (7) of piston rod (2) so that rotation of the drive member (6) relative to the housing (5) results in a longitudinal movement of the piston rod (2).

7. An injection device according to claim 5, wherein the drive member (6) is adapted to be connected to the dose setting member (1) via a ratchet (13).

8. An injection device according to claim 5, wherein the torsion spring (12) is arranged between the housing (5) and the dose setting member (1) in such a way that when the dose setting member (1) is rotated around the piston rod (2), the torsion spring (12) is strained.

9. An injection device according to claim 8, wherein the torsion spring (12) is a helical spring which extends coaxially with the piston rod (2).

10. An injection device according to claim 5, further comprising a locking member (4) adapted to fixate the piston rod (2) in such a way that no relative rotation between of the piston rod (2) and the housing (5) is possible when the locking member (4) is in its locking position.

11. An injection device according to claim 10, further comprising a release button adapted to release the locking member (4) from its locking position.

12. An injection device according to claim 11, wherein the release button is positioned in the distal half of the length of the injection device.

13. An injection device according to claim 5, further comprising a stopping member for defining an outer position of the dose indicator barrel (9), the outer position of the dose indicator barrel (9) corresponding to a maximum obtainable dose.