Injection Device

Abstract

The application concerns an injection device for apportioning set doses of a drug from a reservoir (40) to a subject. The injection device comprises a housing having an interior thread (101,112) formed as an outwardly pointing thread (101,112) carried on an upstanding tower centrally located in the pen shaped device. This outwardly pointing thread (101,112) forms a first thread connection with the interior thread of the rotatable scale drum (90). The injection device further comprises a driver (70) for moving the piston rod (120) forward when moved axially. The driver (70) operates the piston rod (120) through a second thread connection having a pitch different than the first thread connection.

Description

THE TECHNICAL FIELD OF THE INVENTION[0001]The invention relates to an apparatus such as an injection pen for delivering a drug to the human body preferably in a subcutaneous way and especially to a user energized injection pen having a rotatable scale drum.DESCRIPTION OF RELATED ART[0002]In the disclosure of the present invention reference is mainly made to the treatment of diabetes by injection of insulin; however this is only an exemplary use of the present invention.[0003]Injection pens are mainly made for users who have to inject themselves frequently, e.g. people suffering from diabetes. A number of demands are set to such injection pens. The setting of a dose must be easy an unambiguous and it must be easy to read the set dose. It must be possible with a minimum of trouble to cancel or change a wrongly set dose and when the dose is injected the dose setting must return to zero. When a prefilled injection pen is in question, i.e. an injection pen which is disposed of when the r...

AI Technical Summary

Benefits of technology

[0010]Having regard to the above-identified prior art devices, it is an object of the present invention to provide a drug delivery device which eliminates disadvantages in the prior art drug delivery device. It is especially an object to provide a drug delivery device having a reduced displacement of the push button and a reduced friction making the drug delivery device more user friendly. Further it is an object to provide an injection device were all rotating parts are encapsulated.Claim 1:

[0031]This can be accomplished by preventing the drive sleeve from rotating relatively to the housing.

Problems solved by technology

If the scale drum e.g. were a little loose in the thread connection an erroneous dose size could be displayed, however if it were too tight in the thread connection, it would be difficult to press back the dose setting knob.

When a large dose has been set, the distance from the device itself to the push button is considerable thereby making it difficult for people with small hands or reduced dexterity to reach behind the push button.

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