fig1 schematically illustrates a dose display mechanism having a housing 10 that comprises a first and a second dose displaying window 12 , 14 . the housing 10 is of substantially tubular shape . its cylinder long axis extents along an axial direction 20 and its peripheral wall substantially follows a circumferential direction 22 being substantially perpendicular to the elongation of axes 20 . the displaying windows 12 , 14 may comprise any suitable opening in the housing . in a rather simple embodiment , the windows 12 , 14 merely comprise a hole or a through opening in the housing . in other embodiments , the displaying windows 12 , 14 may comprise a transparent cover that allows to visualize and to display the actual device configuration . typically , the displaying windows 12 , 14 are adapted to provide dose - related information by displaying numerical and / or graphical symbols , such as digits , numbers or other suitable characters . inside the housing 10 , there is arranged a tubular shaped dose setting dial 16 , which is exemplary illustrated in fig2 in an unrolled state . fig3 shows the respective dose setting dial 16 ′ in its rolled up tubular shape . as can be seen from fig2 , the dose setting dial comprises a first and a second helical dose indicating scale 18 , 19 . said scales 18 , 19 are axially and circumferentially offset relative to each other . as further indicated by the helical thread 15 , the dose setting dial is typically subject to a combined axial and circumferential displacement relative to the housing 10 during a dose setting procedure . the first and the second dose indicating scales 18 , 19 extend parallel with respect to each other . both dose indicating scales 18 , 19 comprise the same information contents , typically displaying a regular and equidistant graduation of incrementing numbers . the two dose indicating scales 18 , 19 are readable from different device orientations , respectively . for reading the first dose indicating scale 18 , the dose setting dial 16 or the respective drug delivery device should be kept in an upright orientation . for reading of the second dose indicating scale 19 , the dose setting dial has to be rotated by 180 °. hence , the device has to be held upside - down , which for the given type of device is typical for a left - handed user . orientation of the information content , hence the presentation of the respective numbers or symbols of each dose indicating scale differs by substantially 180 °. the axial and circumferential offset of first and second dose indicating scales 18 , 19 corresponds to the respective axial and circumferential offset of first and second displaying windows 12 , 14 of the housing 10 . in this way , the illustrated dose display mechanism 10 is adapted to show identical dose - related information in both windows 12 , 14 simultaneously in different , typically flipped orientations . in this way , the display mechanism and a respectively equipped drug delivery device is universally applicable for both , right - handed and left - handed users . as further illustrated in fig2 a digit 24 of the first dose indicating scale 18 is circumferentially offset to the identical digit 26 of the second dose indicating scale 19 . the two digits 24 , 26 , hence , their corresponding dose indicating scales 18 , 19 are circumferentially offset by 180 °. in the embodiment according to fig1 to 3 , the digit 24 appears at the position of the first window 12 when the digit 26 of the second dose indicating scale simultaneously appears at the displaying window 14 . as further illustrated , an imaginary connection line 28 connecting identical digits 24 , 26 of first and second dose indicating scales 18 , 19 extends at an inclination with respect to the longitudinal axes 20 as well as with respect to the circumferential direction 22 . in the embodiment according to fig4 to 7 , the housing 30 comprises a single dose displaying window 32 , which is divided in first and second display sections 33 , 34 . here , the first display section 33 is arranged in an overlapping way with a corresponding first indicating scale 38 as illustrated in fig7 . correspondingly , the second display section 34 overlaps with a respective second dose indicating scale 39 . depending on whether the dose display mechanism or the correspondingly equipped drug delivery device is intended for right - handed or left - handed use , respectively , an appropriate cover element 37 can be used to cover one of said display sections 33 , 34 . the cover element 37 may either permanently or re - configurably attached to the respective display sections 33 , 34 . in this way , a respective dose display mechanism can be configured or even re - configured for the purpose of right - handed or left - handed usage . since first and second display sections 33 , 34 of the display window 32 substantially overlap in circumferential projection but are located axially next to one another , the dose setting dial 36 as shown in fig7 comprises a different configuration compared to the dose setting dial 16 as illustrated in fig2 . as can be seen from its unrolled configuration , the dose setting dial 36 also comprises two parallel oriented but inclined or helically extending dose indicating scales 38 , 39 . here , the numbers 40 , 42 of said scales 38 , 39 are upside - down with respect to each other . appropriate reading of number 40 requires a counter clockwise rotation of 90 °, whereas proper reading of a digit 42 of the other dose indicating scale 39 requires clockwise rotation by 90 °. in contrast to the dose setting dial 16 of fig2 , the dose setting dial 36 as illustrated in fig7 comprises first and second dose indicating scales 38 , 39 that are merely offset in axial direction with respect to each other . as can be seen from fig7 , identical numbers of first and second dose indicating scales 38 , 39 axially overlap . correspondingly , a not further illustrated imaginary line connecting identical numbers 40 , 42 of first and second dose indicating scales 38 , 39 substantially extends in axial direction . also here , the dose setting dial 36 comprises a helical thread 35 optionally providing a threaded engagement of housing 30 and dose setting dial 36 . by means of such a screw structure , the dose setting dial is allowed to rotatably move towards a proximal end of the drug delivery device during dose setting . in a third embodiment according to fig8 and 9 , the housing 50 also comprises two diametrically opposed displaying windows 52 , 54 . but here , the displaying windows 52 , 54 axially overlap . they are typically circumferentially offset by about 180 °. as further illustrated in fig9 , the respective dose setting dial 56 comprises two parallel oriented helical extending dose indicating scales 58 , 59 , each of which comprising substantially the same information content in form of graduated display units that are in turn represented by numbers 60 , 62 . comparable to the dose setting dials 16 , 36 also the dose setting dial 56 comprises a helical thread 55 indicating the helical - like motion of the dial 56 relative to the housing 50 during a dose setting procedure . since the first and second displaying windows 52 , 54 are merely circumferentially offset with respect to each other , the same applies to the corresponding dose indicating scales 58 , 59 . in the illustration of fig9 , the imaginary position of first and second displaying windows 52 , 54 is illustrated , each of which simultaneously displaying the same number 60 , 62 , but represented in different orientations , that are flipped by 180 ° with respect to each other . generally , the dose setting dial may be releasably connected to a not further illustrated drive mechanism of a drug delivery device , typically by some clutch means . for setting of the dose , the dose setting dial may be rotated together with an inner cylinder or a comparable component of the drive mechanism . typically , during dose dispensing , the clutch means may disengage the dose setting dial from the drive mechanism . further , the dose setting dial may comprise one or more stops to limit the maximum amount of a single dose .
the present invention relates to a drug delivery device , in particular to the dose display mechanism of a drug delivery device comprising : a housing of substantially tubular shape and having at least a first dose displaying window , a dose setting dial rotatably arranged in the housing ) and comprising a first and a second helical dose indicating scale on its peripheral surface , wherein the information contents of the first dose indicating scale and the second dose indicating scale are arranged in different orientations .