Patent attributes
The present invention relates to a medicament delivery device such as an injector for self-administration of a medicament. Those using such devices are often infirm or have impaired vision. There is accordingly a dead for a medicament delivery device in which an amount of a dosage of medicament to be delivered can be selected relatively quickly by the firm and infirm alike and in which the amount of the dosage may readily be controlled and determined. Also there is a need to display the amount of the dialed dosage of medicament on the rotatable knob in figures sufficiently large and clear to be legible by those having a degree of impaired vision. There is disclosed a dose dial mechanism for a medicament delivery device having a housing, the dose dial mechanism comprising a dose dial element having a first thread for engagement with the housing and a dial sleeve member having a second thread for engagement with the housing; in which the dial sleeve member is coupled to the dose dial element so as to allow relative axial movement and inhibit relative rotational movement therebetween, and in which the pitch of the second thread is different from the pitch of the first thread so as to cause a different axial displacement of the dial sleeve member during axial displacement of the dose dial element.
