Patent Description:
A variety of diseases exists that require regular treatment by injection of a medicament. Such injection can be performed by using injection devices, which are applied either by medical personnel or by patients themselves. As an example, type-<NUM> and type-<NUM> diabetes can be treated by patients themselves by injection of insulin doses, for example once or several times per day. For instance, a pre-filled disposable insulin pen can be used as an injection device. Alternatively, a re-usable pen may be used. A re-usable pen allows replacement of an empty medicament cartridge by a new one. Either pen may come with a set of one-way needles that are replaced before each use. The insulin dose to be injected can then for instance be manually selected at the insulin pen by turning (dialling) a dosage knob and observing the actual dose from a dose window or display of the insulin pen. The dose is then injected by inserting the needle into a suited skin portion and pressing an injection button of the insulin pen. To be able to monitor insulin injection, for instance to prevent false handling of the insulin pen or to keep track of the doses already applied, it is desirable to measure information related to a condition and/or use of the injection device, such as for instance information on the injected insulin type and dose.

It has been described, for instance in <CIT>, to provide a supplementary device comprising a mating unit for releasably attaching the device to an injection/drug delivery device. The device includes a camera and is configured to perform optical character recognition (OCR) on captured images visible through a dosage window of the injection pen, thereby to determine a dose of medicament that has been dialled into the injection device. In order for such a supplementary device to successfully determine the dose, the dosage window must remain stationary. However not all drug delivery devices operate in this way. <CIT> discloses markings visible through an inspection window, and a separate inspection site being illuminated by visible and/or non-visible light for determining reflection properties of the site.

Furthermore it may be desirable that the supplementary device enables manual reading of dose information, e.g. through a dose indicating window of the drug delivery device. The supplementary device should therefore not obstruct a dose indicating window on the outer surface of a housing of the drug delivery device. It is also known to provide encoded information, e.g. on a number sleeve of a drug delivery device, which encoded information is recognizable by the supplementary device attached to the drug delivery device. Since the encoded information is located on a moveable element of the drug delivery device the size of the code may limit the precision of code detection. In typical situations only a specific portion of the code is readable by the supplementary device or sensor device. For providing a high degree of accuracy a rather high density of code information must be provided on a moveable element of the drug delivery device. Reducing the geometric size of the code and the code information might be detrimental to the reading or sensing performance of the sensor device or of the supplementary device. Enlarging of the code or code information, e.g. on the outer surface or outer circumference of a number sleeve is often not possible since the available space on the outer surface of a number sleeve is rather limited.

It is therefore an object of one aspect of the invention to provide a drug delivery device and a corresponding sensor device, hence a drug delivery system comprising a drug delivery device and a sensor device that enable detection and reading of encoded information on a moveable element of the drug delivery device with high precision and without increasing the size of the moveable element. It is a further aim to optimize the available space on the outer circumference of a moveable element, hence of a number sleeve of a drug delivery device.

The invention is defined by the subject-matter of claims <NUM> and <NUM>.

According to a first aspect a drug delivery device for setting and for injecting of a dose of an injectable medicament is provided. The drug delivery device comprises an elongated housing that extends along a longitudinal axis. The longitudinal axis defines an axial direction. The elongated housing extending in axial direction has a sidewall with at least a first aperture. The aperture may comprise a transparent window or may be provided as a cut-out in the sidewall of the elongated housing. The drug delivery device comprises at least one number sleeve that is rotatably supported inside the housing. The number sleeve comprises an outer surface. During setting of a dose of a medicament the number sleeve is rotatable in a dose incrementing direction. During dispensing of a dose the number sleeve is rotatable in a dose decrementing direction to return into its initial zero dose configuration. A first portion of the outer surface of the number sleeve is visible through the first aperture. The number sleeve comprises a non-visible code in the region of the first portion. Consequently, the non-visible code is unobstructed and visibly accessible through the first aperture. As the number sleeve is rotated, e.g. during dose setting a sequence of non-visible code fragments passes by the first aperture.

By providing a non-visible code in the region of the first portion the size of the non-visible code can be comparatively large. The non-visible code may overlap with visible information provided on the outer surface of the number sleeve. Making use of a non-visible code is therefore an effective means for saving space and for increasing the encoded information density on the outer surface of the number sleeve. The non-visible code is not visible by the human eye. However and when making use of an appropriate reading device the non-visible code is exclusively detectable and readable by such a reading device, e.g. by a sensing arrangement of a sensor device or supplementary device removably attachable to the drug delivery device.

In a typical application scenario the first aperture is completely covered by a sensing arrangement of the sensor device when attached to the drug delivery device. Hence, the first aperture is not visible to a user of the device when making use of the sensor device or supplementary device.

In this way, the total size of the non-visible code can be enlarged to a suitable extent so as to provide a sufficiently precise reading of the non-visible code.

The non-visible code comprises a code or code pattern provided on the outer surface of the number sleeve. The non-visible code may comprise an optical code. It may comprise a one- or two-dimensional code pattern, which is present on the outer surface of the number sleeve but which is invisible for a person under ordinary circumstances, i.e. when illuminated with electromagnetic radiation in the visible spectral range.

According to one embodiment the non-visible code is reflective and/or absorptive in non-visible spectral ranges of electromagnetic radiation. In this way the non-visible code is invisible to the human eye. It is exclusively readable by a sensing arrangement that operates in a spectral range of electromagnetic radiation outside the visible spectral range. Hence, the non-visible code and the sensing arrangement of the sensor device are configured to operate outside a spectral range that ranges from <NUM> to <NUM>. Typically, the non-visible code is reflective either in the UV spectral range, i.e. below <NUM>, below <NUM> or even below <NUM> or the non-visible code is reflective in the infrared spectral range, i.e. at wavelength above <NUM>, above <NUM> or above <NUM>. In this way, the non-visible code is invisible to the human eye.

Implementing a UV reflective code is of particular benefit since the comparatively low wavelength is particularly suitable for high resolution imaging. Moreover, UV light for reading of the non-visible code will not come along with a thermal heating of the outer surface and hence of the number sleeve of the drug delivery device. This may be beneficial for such medicaments that are heat sensitive.

The non-visible code is printed or coated on the outer surface of the number sleeve by way of a luminescent paint or luminescent ink that exhibits a well-defined luminescent response in a desired spectral range that is outside the visual spectral range. The luminescent paint, ink or the luminescent coating may be fluorescent or phosphorescent.

According to another embodiment the non-visible code comprises a reflective microstructure on the outer surface of the number sleeve. The reflective microstructure may be a reflective zero-order diffractive microstructure. The microstructure may comprise various steps or gaps. The microstructure further exhibits a desired reflectance in the non-visible range of electromagnetic radiation so that due to reflection of respective electromagnetic waves a diffraction pattern will arise that is indicative of the non-visible code in the region of the first portion on the outer surface of the number sleeve. It is particularly conceivable, that the reflective zero-order diffractive microstructure provides a kind of a holographic image when exposed to electromagnetic radiation of a desired wavelength, e.g. when subject to UV or infrared radiation.

The diffractive and reflective microstructure may be rather compact. An image creatable by the zero-order diffractive microstructure may be much larger than the microstructure itself. In this way, the reflective microstructure may inherently come along with a magnification effect.

According to another embodiment the at least first portion of the outer surface is metalized or comprises a metal coating. A metalized outer surface or a respective metal coating may be provided with the reflective microstructure. It is even conceivable, that the reflective microstructure is provided on a flexible foil that may be attached to the outer surface of the number sleeve. The flexible foil, the metalized outer surface or the metal coating thereof may be considered as a kind of a holographic label providing non-visible code for a given range of electromagnetic radiation. The reflective microstructure may comprise diffractive optical variable image device (DOVID) or may behave like a DOVID.

According to another embodiment the outer surface of the number sleeve comprises a second portion with numerous visible symbols extending along a helical pattern. The visible symbols may represent a sequence of increasing or decreasing numbers, wherein each number is representative for a particular dose size in accordance to a standardized unit system. If the drug delivery device is for instance configured for the injection of a medicament such like insulin, the visible symbols in the second portion of the outer surface may represent international units (IU).

The second portion extending along a helical pattern may comprise visible symbols, such like <NUM>, <NUM>, <NUM>,. up to <NUM> or even up to <NUM>. The helical pattern of the visible symbols of the second portion may comprise numerous revolutions around the outer circumference of the number sleeve. The visible symbols, hence the dose numbers are typically printed on the outer surface. They are readable and viewable through a second aperture or window of the elongated housing.

There are different configurations conceivable for the relative movement of number sleeve and elongated housing. It is conceivable that the number sleeve is rotatable along a helical path with regard to the elongated housing. Then, the second aperture or window will be located at a fixed position on the outer surface of the sidewall of the elongated housing. As the number sleeve is subject to a helical rotation a sequence or increasing or decreasing numbers will show up in the second aperture or window of the elongated housing. In other configurations it is conceivable, that the number sleeve is axially fixed inside the elongated housing. Then there will be provided a moveable element with the second aperture that moves along the second portion along the longitudinal axis, thereby visualizing only one or a few of the visible symbols at a time.

According to another embodiment the first portion and the second portion of the outer surface of the number sleeve overlap at least in sections. In this way, the non-visible code that coincides with or entirely fills the first portion overlaps at least a section of the visible symbols that coincide with or entirely fill the second portion on the outer surface of the number sleeve. The at least partial overlap of the first portion and the second portion, hence the overlap of the non-visible code with the visible symbols is beneficial in order to increase the information density on the outer surface of the number sleeve. Furthermore, the non-visible code may be provided with an increased size. In particular, the axial elongation of the non-visible code may be larger than the axial extension of a single visible symbol. Since the visible symbols are reflective in the visible spectral range and since the non-visible code is exclusively reflective in a non-visible spectral range a mutual overlap of visible symbols and non-visible code is generally conceivable.

It is of particular benefit, when the paint, the ink or the coating that provides the non-visible code is substantially transparent for electromagnetic radiation in the visible spectral range. Alternatively or additionally it is also conceivable, that the visible symbols are printed or coated in the second portion on the outer surface of the number sleeve with a paint, an ink or a coating that is substantially transparent in the UV spectral range and/or in the IR spectral range. Printing or applying the non-visible code on top of the visible symbols or vice versa applying the visible symbols above the non-visible code will then not lead to an obstruction of the code or symbols that are located beneath.

According to a further embodiment the non-visible code is located on top of at least one or several of the visible symbols or wherein at least one or several of the visible symbols are located on top of the non-visible code. In situations or configurations wherein the non-visible code is located on top of one or several of the visible symbols the non-visible code is typically transparent to electromagnetic radiation in the visible spectral range. In another scenario, wherein at least one or several of the visible symbols are located on top of the non-visible code the visible symbols are made of a visible material, e.g. a particular paint or ink that is substantially transparent for electromagnetic radiation in the UV spectral range and/or in the IR spectral range.

In this way the surface portion on the outer surface of the number sleeve that can be used for the non-visible code can be enlarged to such an extent that is beneficial for a precise and reliable automatic sensing and reading of the non-visible code without obstructing or deteriorating the visibility of the visible symbols on the outer surface of the number sleeve.

According to another embodiment the non-visible code is a two-dimensional code having a code array with numerous code lines and code columns. One of the code lines and the code columns extends in axial direction and wherein the other one of the code lines and the code columns extends in a tangential direction on the outer surface of the number sleeve, which is typically cylindrically-shaped. So the two-dimensional non-visible or invisible code is of cylindrical geometry and aligns parallel to the cylindrical shape of the number sleeve. It is generally conceivable, that the two-dimensional non-visible code is aligned parallel to the cylindrical shape or contour of the number sleeve whereas the visible symbols in the second portion are arranged along a helical pattern. The visible code may comprise a Hamming code, a de Bruijn sequence and/or a Manchester coding. A Manchester coding splits each de Bruijn sequence in two separate sequences, so that a processor or the sensing arrangement would recognize the transition between different bits of code rather than recognizing different bits of code as such.

The two-dimensional non-visible code may comprise a discrete code, hence a binary code, where the code pattern changes instantly for each increment. The two-dimensional code may also comprise a grayscale code, that changes floatingly from one gray value to another. When implemented as a discrete binary code, values of <NUM> or <NUM> are detected based on the intensity of the spatial light distribution that is reflected by the code and that reaches a sensing arrangement, typically comprising an optical detector with a respective decoder.

According to another embodiment the size of the first aperture of the housing through which at least a portion of the non-visible code is viewable or readable is at least as large as the height of a code column of the two-dimensional code. Typically, the size of the first aperture in tangential direction is even larger than or equal to the tangential extension of two adjacently located code lines. In this way a visual field of a sensing arrangement of the sensor device may contain always a complete code line or a complete code column.

By having a tangential size larger than or equal to the tangential extension of two adjacently located code lines even two code lines may appear simultaneously in the first aperture. As the number sleeve is dialed further, one of the two code lines will disappear at the benefit of a third code line appearing then in the first aperture. Typically, the first aperture comprises an axial extension larger than a tangential extension. The first aperture typically comprises an axial extension that is substantially equal to the axial length of a code line. A code line may be twice, four times, six times, or even ten times as large as the tangential extension of the code line, hence the height of a code field of a code line.

The rather rectangularly-shaped first aperture is of particular benefit for capturing and sensing the optical reflection of the non-visible code at a time. This enables a precise sensing and reading of the non-visible code information.

According to another embodiment the drug delivery device further comprises a movable element, typically configured as a gauge element which is movable along an axial path parallel to the longitudinal axis. The gauge element comprises the second aperture in form of a gauge window through which the outer surface of the number sleeve is visible. The gauge window is located beneath a third aperture in the sidewall of the housing. The third aperture in the sidewall of the housing typically extends in longitudinal or axial direction so that the gauge window of the gauge element is permanently located inside the third aperture.

Typically, the gauge element is purely axially slidably displaceable relative to the housing of the drug delivery device. The gauge element is rotationally locked to the housing of the drug delivery device and cannot be rotated with regard to the longitudinal axis as a rotation axis. In operation the gauge element covers that portion of the outer surface of the number sleeve that is located beneath the second aperture of the housing. In this way the number sleeve is effectively covered by the non-transparent gauge element except for that portion of the number sleeve that is visible through both, the third aperture in the sidewall of the housing and through second aperture, hence through the gauge window.

As a dose is for instance set the number sleeve is exclusively subject to a rotation relative to the housing whereas the gauge element is exclusively subject to an axial displacement relative to the housing. The axial movement of the gauge element corresponds with the rotational movement of the number sleeve and with the pitch of the helical pattern of the visible symbols of the second portion of the outer surface of the number sleeve. In this way, a sequence of increasing numbers will show up in the axially sliding gauge window as the number sleeve is subject to a dose incrementing rotation during setting of a dose.

According to another embodiment the number sleeve is axially fixed inside the housing and the number sleeve located radially inside the gauge element. In other words, the gauge element at least covers a portion of the number sleeve. The gauge element is located radially between the outer surface of the number sleeve and an inner surface of the housing. Furthermore, the number sleeve is threadedly engaged with the gauge element. It is due to the threaded engagement of number sleeve and gauge element that the gauge element is subject to a longitudinal or axial sliding motion as the number sleeve is rotated inside the housing. The gauge element is further in axial slidable engagement with the housing. For this the gauge element and the housing comprise at least one pair of radially extending protrusion engaging with a longitudinally extending groove by way of which a kind of a splined engagement is provided between the gauge element and the housing. In this way the gauge element is prevented from rotating relative to the housing.

In another embodiment the gauge element comprises at least one detectable indicator at a predetermined axial location. The total information content provided by the non-visible code may not be sufficient to encode all settable dose sizes of the drug delivery device. It is conceivable, that the non-visible code comprises only four or five bits that are not sufficient to encode all numbers between <NUM> and e.g. <NUM>. During setting of a dose it is hence conceivable, that the number sleeve is subject to numerous revolutions. Since the number sleeve is axially fixed inside the housing its non-visible code will repeatedly show up in the first aperture.

In order to provide an absolute and unequivocal determination of a dose size the gauge element is provided with at least one detectable indicator at a predetermined axial location. Since the gauge element is subject to an axial displacement also the detectable indicator will be moved in axial direction as a dose is dialed. A sensor device removably attachable to the drug delivery device typically comprises a sensing arrangement to at least roughly detect the axial position of the detectable indicator of the gauge element. In this way the sensing arrangement may precisely distinguish between various revolutions of the number sleeve inside the housing.

In another aspect the invention also relates to a sensor device that is removably attachable to the drug delivery device as described above. The sensor device comprises a sensing arrangement overlying the first aperture when the sensor device is attached to the drug delivery device. The sensing arrangement is configured to receive optical signals from the non-visible code as the non-visible code is viewable through the first aperture. The sensor device further comprises a circuitry that is connected to the sensing arrangement. The circuitry is configured to process signals obtained from the sensing arrangement when the sensing arrangement receives optical signals.

The sensing arrangement is further configured to read a portion of the non-visible code through the first aperture and the circuitry is further configured to determine, based on the externally visible portion of the non-visible code, the angular position of the number sleeve relative to the housing. From this the circuitry is configured to derive information relating to a drug dose to which the drug delivery device is currently dialed.

The sensing arrangement typically comprises at least a light source and an optical detector that are operable in a non-visible spectral range. The light source and the detector may operate in the UV spectral range or in the IR spectral range. The optical detector typically comprises an array of numerous light sensitive pixels in order to capture a two-dimensional image of the non-visible code that is viewable through the first aperture of the housing of the drug delivery device.

According to another embodiment the sensor device comprises an array of sensors that are arranged within the sensor device and that are separated in the longitudinal or axial direction. The sensors are configured to detect the axial position of the detectable indicator of the gauge element. The sensors or the array of sensors may be implemented as optical sensors. However, the sensors may be also implemented as capacitive or inductive sensors so as to be capable to detect the axial position of the detectable indicator of the gauge element.

In a further aspect there is also provided a drug delivery system comprising a drug delivery device as described above and further comprising a sensor device or supplementary device removably attachable to the drug delivery device at least for reading and/or tracking of a dose size information.

or a pharmaceutically acceptable salt or solvate of any one of the afore-mentioned Exendin-<NUM> derivative.

Hormones are for example hypophysis hormones or hypothalamus hormones or regulatory active peptides and their antagonists as listed in Rote Liste, ed. <NUM>, Chapter <NUM>, such as Gonadotropine (Follitropin, Lutropin, Choriongonadotropin, Menotropin), Somatropine (Somatropin), Desmopressin, Terlipressin, Gonadorelin, Triptorelin, Leuprorelin, Buserelin, Nafarelin, Goserelin.

Antibodies are globular plasma proteins (~150kDa) that are also known as immunoglobulins which share a basic structure. As they have sugar chains added to amino acid residues, they are glycoproteins. The basic functional unit of each antibody is an immunoglobulin (Ig) monomer (containing only one Ig unit); secreted antibodies can also be dimeric with two Ig units as with IgA, tetrameric with four Ig units like teleost fish IgM, or pentameric with five Ig units, like mammalian IgM.

It will be further apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention as it is defined by the claims. Further, it is to be noted, that any reference numerals used in the appended claims are not to be construed as limiting the scope of the invention.

In the following, an embodiment of the display arrangement, the drive mechanism and the drug delivery device is described in detail by making reference to the drawings, in which:.

<FIG> shows two views of a drug delivery device <NUM>, in this example an injection device, with which a sensor device (also referred to as a supplementary device - not shown) according to various embodiments of the invention may be used.

The drug delivery device <NUM> of <FIG> is configured such that a user is able to adjust the drug dosage (or number of drug doses) that is to be delivered (or dispensed) using the device <NUM>. In the example of <FIG>, this is achieved by rotating (or dialling) a dose selector <NUM> which causes an internal dialling mechanism (not shown) to adjust an amount of the drug that is to be dispensed once a drug delivery mechanism (not shown) is actuated. In this example, the drug delivery mechanism is actuated by pressing a button <NUM> on the device.

The drug delivery device <NUM> comprises an external housing <NUM> in which is formed at least one aperture or window 13A, 13B. As will be appreciated, an aperture may simply be a cut-away area of the external housing <NUM>, whereas a window may be a transparent portion of the housing through which components of the device may be seen. For convenience, the at least one aperture or window 13A, 13B, will hereafter simply be referred to as the third aperture 13A and the fourth aperture 13B, respectively.

The third and fourth apertures 13A, 13B allow a movable gauge element <NUM> to be visible from the exterior of the housing <NUM>. The drug delivery device <NUM> is configured such that as the dose selector <NUM> is dialled, the movable gauge element <NUM> is caused to be moved thereby to indicate a selected dose to the user. More specifically, as the dose selector <NUM> is dialled, the gauge element <NUM> moves axially along an underlying surface 15A, 15B thereby to indicate the selected dose. In the example of <FIG>, a surface 15A underlying at least part of the gauge element <NUM> is located on the outer surface of a number sleeve <NUM>. The underlying surface 15A and/or the underlying surface 15B may coincide with the outer surface <NUM> of the number sleeve <NUM>.

The number sleeve <NUM> as shown in <FIG> has numbers <NUM> indicative of drug doses provided on its outer surface, with the number indicating the currently selected dose being visible through the third and fourth apertures 13A, 13B. In this example, the number sleeve <NUM> is visible through a gauge window or through a second aperture <NUM>-<NUM> formed in the movable gauge element <NUM>. Other parts of the movable gauge element <NUM> are discussed below.

The uppermost view of the drug delivery device <NUM> shown in <FIG> illustrates the situation before any dialling has been performed. Consequently, the movable gauge element <NUM> is at its first (or initial) position at a first end of the path along which it is able to move. In this example, when the movable gauge element <NUM> is at the first end of its path, the portion of the number sleeve <NUM> that is visible through the gauge window or through the second aperture <NUM>-<NUM> shows the number zero (i.e. a zero dose).

The bottommost view of the drug delivery device <NUM> shown in <FIG> illustrates the situation after dialling has been performed. Consequently, the movable gauge element <NUM> has moved axially along the path that is visible through the third aperture 13A away from its first position. In this example, the device <NUM> has been dialled to its maximum dose and as such, the movable gauge element <NUM> has moved to the second end of its path. The maximum dose in this example is "<NUM>" and so the portion of the number sleeve <NUM> that is visible through the gauge window <NUM>-<NUM> shows the number "<NUM>".

The number sleeve <NUM> and the respective underlying surface 15A underlie and are visible through the third aperture 13A, whereas a further underlying element 15B underlies and is sometimes visible through the fourth aperture 13B. The further underlying surface 15B may or may not include any numbers. The further underlying surface 15B is visually distinguishable from a second part <NUM>-<NUM> of the movable gauge element <NUM> which overlies it and which is configured to move axially along it. For instance, the second part <NUM>-<NUM> of the movable gauge element <NUM> may be of a different reflectance to the further underlying surface 15B. For example, one of the gauge element <NUM> and the underlying surface 15B may be of a light colour (e.g. may be made of a light coloured polymer) and the other may be of dark colour (e.g. may be made of a dark coloured polymer).

The user may, therefore, be able to determine the selected dose by determining the proportion of the third aperture 13A in which the gauge element <NUM> (specifically, the second part <NUM>-<NUM>) is visible compared to the proportion in which the further underlying surface 15B is visible. This can be seen from <FIG>, in which, when the device <NUM> is dialled to its zero dose, the gauge element <NUM> covers the entire length of the path that is visible through the fourth aperture 13B. In contrast, when the device <NUM> is dialled to its maximum dose, none of the gauge element <NUM> is visible through the second window. Instead, the further underlying surface 15B is visible along the entire length of the path defined by the fourth aperture 13B.

The number sleeve <NUM> underlying the gauge element <NUM> is also visually distinguishable from the movable gauge element <NUM> which overlies it and which is configured to move axially along it. For instance, gauge element <NUM> may be of a different reflectance to the number sleeve <NUM>. For example, one of the gauge element <NUM> and the underlying surface 15A may be of a light colour (e.g. may be made of a light coloured polymer) and the other may be of dark colour (e.g. may be made of a dark coloured polymer). In the examples shown in the Figures, the number sleeve <NUM> and underlying surface 15B are of a higher reflectance than the movable gauge element <NUM>.

<FIG> and <FIG> are simplified schematics of components of a drug delivery device such as that of <FIG>. The purpose of <FIG> is to illustrate the operation of a drug delivery device <NUM> such as that of <FIG>; they are not intended to be accurate representations of the exact design of the components.

<FIG> is a simplified schematic of the number sleeve <NUM> with the underlying surface 15A, that coincides with the outer surface <NUM> on the outer circumference of the tubular sleeve <NUM>. The sleeve <NUM> has numbers provided on its surface. In some examples, the numbers, ranging from the minimum dose to the maximum dose, may be provided helically around the surface of the number sleeve.

<FIG> is a simplified schematic of a movable gauge element <NUM>. The gauge element <NUM> comprises a first section <NUM>-<NUM> in which the gauge window <NUM>-<NUM> is provided. In this example, the first section is <NUM>-<NUM> a collar which is configured to encircle the number sleeve <NUM> and its underlying surface 15A (as can be seen in <FIG>). Extending in opposite directions from the first section <NUM>-<NUM> are the second part <NUM>-<NUM> and a third part <NUM>-<NUM>. The second and third parts <NUM>-<NUM>, <NUM>-<NUM> extend generally parallel to the longitudinal axis of the number sleeve <NUM>.

The second part <NUM>-<NUM> of the movable gauge element is configured to extend from the first part <NUM>-<NUM> by a length sufficient to fill the entire second window 13B when the movable gauge is in its first position. The second part <NUM>-<NUM> may also serve to obscure a portion of the exterior surface of the number sleeve <NUM>, when the gauge element moves away from its first position. The third part of the movable gauge element <NUM>-<NUM> is configured to obscure a portion of the exterior surface of the number sleeve 15A, when the gauge elements moves between its first and second positions. In this way, only the portion of the number sleeve that underlies the gauge window <NUM>-<NUM> is visible through the third aperture 13A of the device housing <NUM>. The gauge window <NUM>-<NUM> represents a second aperture of the drug delivery device.

The rotational movement NSR of the number sleeve <NUM> and axial movement GE of the gauge element <NUM> are interdependent. Put another way, the dialling mechanism of the device <NUM> is configured such that when number sleeve <NUM> is caused to rotate, the gauge element <NUM> is caused to move or translate axially along its path. Moreover, the degree of rotation of the number sleeve <NUM> corresponds proportionally to the extent of axial movement of the gauge element <NUM>.

<FIG> shows the gauge element <NUM> in its initial position in which, in this example, it indicates a zero dose. <FIG> shows the number sleeve <NUM> and gauge element <NUM> following rotation of the number sleeve <NUM> and translation of the gauge element <NUM> from its first position. <FIG> shows this arrangement of <FIG> within a simplified version of the device housing <NUM>.

Various dialling mechanisms for adjusting a dose to be delivered to a user which transform rotation of a dose selector <NUM> into rotational movement of a number sleeve <NUM> and axial movement of a gauge element <NUM> (as described above) are known in the art. Two such mechanisms are described in <CIT> and <CIT>. As such mechanisms (and also drug delivery mechanisms which cause delivery of the drug once the dose has been dialled) are known in the art, they will not be described herein in any detail.

One specific but non-limiting example of the number sleeve <NUM> is given in the illustration according to <FIG>. The number sleeve <NUM> is of generally tubular shape. It comprises an outer surface <NUM>. The outer surface <NUM> comprises a first portion <NUM> that is provided with a non-visible code <NUM>. In the present illustration also shown in <FIG> the non-visible code <NUM> is exclusively provided in the first portion <NUM>. The first portion <NUM> substantially coincides with the spatial extension of the non-visible code <NUM>. It is only for illustration purpose, that the non-visible code <NUM> is made visible in the various Figures.

On the outer surface <NUM> there is further provided a second portion <NUM>. In the second portion there are provided numerous visible symbols <NUM> that are arranged along a helical pattern <NUM> as it is apparent from <FIG> and <FIG>. The first portion <NUM> and the second portion <NUM> may be substantially overlapping as illustrated in <FIG>. Hence, the non-visible code <NUM> may overlap at least a portion of the visible symbols <NUM> of the helical pattern <NUM>. In this way, the size, in particular the axial size of the two-dimensional non-visible code <NUM> is extended to such a size that the code <NUM> is particularly suitable for a reliable and failure safe reading of the non-visible code information.

In the present embodiment the number sleeve <NUM> is axially fixed inside the housing <NUM> of the drug delivery device <NUM>. Near a distal end <NUM> the number sleeve <NUM> comprises an annular groove <NUM> that engages with a correspondingly-shaped radially inwardly extending structure on the inner surface of the housing <NUM>. It is free to rotate relative to the housing with regard to a central axis that extends parallel to the elongation of the number sleeve <NUM>. Near a proximal end <NUM> the number sleeve <NUM> is provided with an outer thread <NUM> by way of which the number sleeve <NUM> is threadedly engaged with the gauge element <NUM>. The gauge element <NUM> is hindered to rotate relative to the housing <NUM>. It is hence rotatably fixed to the housing <NUM>. Rotation of the number sleeve <NUM> is in some embodiments caused by rotation of the dose selector <NUM>.

One of the gauge element <NUM> and the housing <NUM> may comprise a radial protrusion that engages with an axially extending groove of the other one of the gauge element <NUM> and the housing <NUM>. In this way the gauge element <NUM> is slidably supported inside the housing <NUM> but is rotatably constrained to the housing <NUM>. The gauge element <NUM> typically comprises an inner thread 61A that engages the outer thread <NUM> of the number sleeve <NUM>. A rotation of the number sleeve <NUM> during dose setting or dose dispensing therefore leads to a translational and purely axial sliding motion of the gauge element <NUM>.

When rotating the number sleeve <NUM> the visible symbols <NUM>, hence the dose indicating numbers provided in the second portion <NUM> on the outer surface <NUM> of the number sleeve <NUM> show up in the third aperture 13A and in the second aperture <NUM>-<NUM> as the gauge element <NUM> travels in axial direction relative to the housing <NUM>.

The non-visible code <NUM> of the first portion <NUM> of the outer surface <NUM> of the number sleeve <NUM> is exemplary illustrated in <FIG> and <FIG>. There are illustrated <NUM> code lines and <NUM> code columns that form an array <NUM> of a binary code. Some code lines are exemplary denoted as code lines <NUM>, <NUM> and <NUM> and some columns are denoted as <NUM>, <NUM>, <NUM>.

The housing <NUM> of the drug delivery device <NUM> includes a first aperture <NUM> through which a portion of the number sleeve <NUM>, on which part of the code <NUM> is provided, is visible. The further window <NUM> is positioned and oriented relative to the number sleeve <NUM> such that a portion of the code is externally visible through the further window <NUM> regardless of the rotational orientation of the number sleeve <NUM>. The first aperture <NUM> is positioned and oriented relative to the number sleeve <NUM> such that, as the number sleeve <NUM> rotates through a single complete rotation, different sections of the code <NUM> will be visible at each rotational orientation. The further aperture is, in this example, provided on a different side of the device housing <NUM> (or, if the housing is cylindrical or otherwise rounded, around the exterior surface of the device housing <NUM>) from the at least one window 13A, 13B through which the movable gauge element <NUM> is visible. In this way, the movable gauge element <NUM> does not obstruct the code <NUM> from view.

As shown schematically in <FIG>, the sensor device <NUM> comprises a circuitry <NUM> with a sensing arrangement <NUM>. The sensing arrangement <NUM> is arranged within the sensor device <NUM> such that, when the sensor device <NUM> is attached to the drug delivery device <NUM>, the sensing arrangement <NUM> is operable to read the non-visible code <NUM> that is externally visible on the drug delivery device <NUM> through a first aperture <NUM> in the housing <NUM>. In this example, at least part of the encoded information <NUM> is visible through the first aperture <NUM>. In some other examples, such as are discussed below, at least part of the encoded information may be provided on a portion of the exterior of the housing <NUM> which underlies the sensing arrangement <NUM>.

The sensing arrangement <NUM> may be of any suitable type as long as it enables the encoded information <NUM> to be read. For instance, the sensing arrangement may be an optical sensing arrangement comprising a camera.

The size of the first aperture <NUM> is illustrated in <FIG> and <FIG> in a dashed rectangle. The size of the first aperture <NUM> is configured to provide visualization of an entire code line <NUM>, <NUM>, <NUM>. In this way and due to the overlapping arrangement of the non-visible code <NUM> with the visible symbols <NUM> the axial size of the non-visible code <NUM> can be enlarged to an extent that provides unequivocal and highly reliable code reading. The code lines <NUM>, <NUM>, <NUM> are aligned in axial direction whereas the code columns <NUM>, <NUM>, <NUM> extend in tangential direction, hence along the outer circumference of the tubular-shaped outer surface <NUM> of the number sleeve <NUM>.

The height of the code columns will equal <NUM> degrees divided by <NUM>, hence the height of each code line may equal about <NUM> degrees. In the presently illustrated embodiment the tangential width, hence the vertical size of the first aperture <NUM> is at least equal to or larger than the size of two adjacently arranged code lines <NUM>, <NUM>. Hence, the total size of the first aperture in tangential direction may be about <NUM> degrees. The present size of the first aperture <NUM> in tangential direction is beneficial in that always at least one complete code line <NUM> will be readable through the first aperture. In the configuration according to <FIG> two entire code lines <NUM>, <NUM> are visible through the first aperture <NUM>.

Taking into account some tolerances of the imaging of the code <NUM> or tolerance of the angular position of the number sleeve of about +/- <NUM> units the tangential size of the first aperture may be increased to about <NUM>°. With an appropriate sensing arrangement <NUM> the reading of the code <NUM> may be conducted even without the start-sections, end sections or 'quiet' sections of the code. Then the tangential size of the first aperture <NUM> may be reduced to about <NUM>° even including the above mentioned tolerance margins.

The sensing arrangement of the sensor device is particularly configured to analyze the captured code lines <NUM>, <NUM>. Moreover, the code sequence may be stored in the circuitry, in particular in a memory <NUM>. The circuitry may be provided with a threshold function to decide which one of the two consecutive code lines <NUM>, <NUM> is dominantly present in the first aperture <NUM>. It may be only for an infinitesimally small angular range that the circuitry will not be able to decide which one of the code lines <NUM>, <NUM> is dominantly present inside the first aperture <NUM>. For this it is of particular benefit, when the tangential size of the first aperture does not exceed but exactly matches with the twofold tangential size of a code line <NUM> or <NUM>.

As soon as the number sleeve <NUM> is dialed further from the configuration according to <FIG> a configuration according to <FIG> may arise. There, only the code line <NUM> is completely visible through the first aperture <NUM> whereas a tangentially preceding and a proceeding code line <NUM> or <NUM> are only visible partially. Depending on the spatial resolution and the pattern recognition of the sensing arrangement and the circuitry <NUM> the sensor device <NUM> is capable to determine that the number sleeve <NUM> has been dialed one increment further.

With the illustrated <NUM> code lines at least <NUM> consecutive dose sizes can be encoded on the outer circumference and on the outer surface <NUM> of the number sleeve. However, for encoding a total number of for instance <NUM> units with an increment of only <NUM> unit ten revolutions of the number sleeve <NUM> would have to be implemented.

In order to reduce the number of revolutions of the number sleeve it is even conceivable, that <NUM> different angular positions can be encoded with the <NUM> code lines. In the present embodiment, each code line may represent an even number of dose units, such like (<NUM>, <NUM>, <NUM>, <NUM>,. If the sensing arrangement detects a configuration according to <FIG> with one completely viewable code line <NUM> and two additional but only partially viewable code lines <NUM>, <NUM> the circuitry <NUM> may recognize such a scenario that the number sleeve is now rotated to an odd dose number (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>,. Dialing the number sleeve <NUM> further for half a code line <NUM> two entire code lines <NUM>, <NUM> will show up in the first aperture <NUM>. Both of these scenarios may be well distinguished by the circuitry <NUM>.

The code <NUM> may comprise a Hamming Code, wherein some portions of the code <NUM> are redundant code fragments. For representing <NUM> angular positions <NUM> bits of codes are substantially sufficient. Some columns of the code <NUM> are used as a start bit or as a stop bit in order to provide a well-defined starting point for the code information. By means of redundant code fragments the security and unequivocal readability o the code <NUM> can be enhanced.

When implemented as a de Bruijn sequence the code may be for instance represented by a sequence of code portions extending all along the helical pattern <NUM> of the visible symbols. Hence, the first portion <NUM> of the number sleeve <NUM> and the second portion <NUM> of the number sleeve with non-visible code and with visible symbols substantially overlap.

Simultaneously to an axial tracking of the gauge element <NUM> the sensing arrangement <NUM> overlying the first aperture <NUM> generates electromagnetic radiation in a non-visible spectral range by means of a light source <NUM>-<NUM>. The electromagnetic radiation, typically UV or IR radiation is directed towards the first aperture <NUM>. Non-visible electromagnetic radiation reflected from the non-visible code <NUM> is reflected towards a detector <NUM>-<NUM> of the sensor device <NUM>. Signals of the detector <NUM>-<NUM> and hence of the sensing arrangement are processed by the circuitry <NUM> in order to track and to determine the actual angular position of the number sleeve <NUM>.

In the sketches of <FIG> it is apparent, that the sensor device <NUM> comprises a body <NUM> by way of which the sensor device <NUM> is detachably fastened to the outer surface of the housing <NUM>. The body <NUM> comprises an axially elongating protruding portion 5A. In this protruding portion 5A an array <NUM> of axial sensors <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> may be positioned. The gauge element <NUM> which is provided with a detectable indicator <NUM> is subject to a well-defined and discrete movement in axial direction as the number sleeve <NUM> has been rotated a complete revolution.

The circuitry <NUM> of the sensor device <NUM> of <FIG> is configured to determine, based on the encoded information <NUM>, information relating to operation of the drug delivery device <NUM>. In some specific examples, the circuitry <NUM> is configured to determine a current dose to which the device <NUM> is dialled, based on the encoded information <NUM> and the signals output from the sensors of the array <NUM>. For instance, the signals output from the array <NUM> may be utilised by the circuitry <NUM> to determine the number of complete rotations of the number sleeve <NUM> that have occurred and the encoded information <NUM> read by the sensing arrangement <NUM> may be utilised to determine the rotational orientation of the number sleeve <NUM>. Put another way, the signals output from the array <NUM> may be used to determine roughly the extent of axial translation of the moveable gauge element <NUM>, with the encoded information <NUM> read by the sensing arrangement being used with the rough determination to more precisely determine the extent of rotation of the number sleeve and/or the translation of the movable gauge element <NUM> in order to determine the currently dialled dose.

The array <NUM> of sensors <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> is capable to detect the axial position of the detectable indicator <NUM> as a dose is dialed or set. The position of the detectable indicator <NUM> along the protruding portion 5A is hence indicative of the number of complete revolutions the number sleeve <NUM> has turned since the beginning of a dose incrementing rotation.

The sensors <NUM>-<NUM> to <NUM>-<NUM> may be implemented as optical sensors. They could be also implemented as magnetic, capacitive or inductive sensors thereby forming a respective magnetic, capacitive or inductive contact-less sensing arrangement. Capacitive, magnetic or inductive sensors allow an arrangement of the body <NUM> of the sensor device <NUM> in a nonoverlapping configuration with the third and fourth apertures 13A, 13B of the housing. Hence, a manual reading of the gauge window <NUM>-<NUM> is unobstructed or unobscured.

<FIG> shows an extremely simplified cut-away view of the components of the delivery device <NUM> as depicted in <FIG> and a simplified schematic illustration of a sensor device <NUM> for use with a delivery device <NUM> such as that described with reference to <FIG>.

The sensor device <NUM> comprises an array <NUM> of axial sensors <NUM>-<NUM> to <NUM>-<NUM> arranged such that, when the sensor device <NUM> is in place on the drug delivery device <NUM>, each axial sensor <NUM>-<NUM> to <NUM>-<NUM> in the array <NUM> is operable to the axial position of a detectable indicator <NUM> that is attached to or which is embedded in the gauge element <NUM> as shown in <FIG>. The sensors <NUM>-<NUM> to <NUM>-<NUM> may be implemented as optical sensor to detect light received from a different location along an externally visible path defined by one of the at least one window 13A, 13B. Each sensor <NUM>-<NUM> to <NUM>-<NUM> may output a signal indicative of an axial position of the gauge element <NUM>. The sensor device <NUM> further comprises circuitry <NUM> configured to receive the signals output from the optical sensors <NUM>-<NUM> to <NUM>-<NUM> of the array <NUM> and, based on the received signals, to determine information associated with a location along the path defined by the window 13A, 13B of the movable gauge element <NUM>. The circuitry <NUM> may be further configured to control operation of the array <NUM>.

The optical sensors <NUM>-<NUM> to <NUM>-<NUM> may be substantially equidistantly spaced from one another along a length generally corresponding to the length of the visible path. The length over which the optical sensors <NUM>-<NUM> to <NUM>-<NUM> are spaced may not be exactly the same as the length of the visible path along which the gauge element <NUM> moves but may be dependent on the length of the visible path with which the sensor device <NUM> is designed to be used.

In some embodiments, the array <NUM> of optical sensors <NUM>-<NUM> to <NUM>-<NUM> extends generally along an axis which, when the sensor device <NUM> is coupled to the delivery device <NUM>, is generally parallel with the axis along which the moveable gauge element <NUM> is configured to move. The axis along which the array <NUM> of optical sensors extends is therefore also generally parallel with the longitudinal axis of the window 13A, 13B.

The rotation of the number sleeve <NUM> is proportional to the axial movement of the movable gauge element <NUM>.

The array <NUM> may comprise the same number of axial sensors <NUM>-<NUM> to <NUM>-<NUM> as the number of complete rotations of the rotatable element 65A that are required to move the movable gauge element <NUM> from its initial to final position. The sensors <NUM>-<NUM> to <NUM>-<NUM> may be distributed adjacent the visible path of the movable gauge element such that after every complete rotation of the rotatable element 65A, the output of a successive optical sensor in the array <NUM> changes. For instance, after the first complete rotation of the rotatable element number sleeve <NUM>, the output of the first sensor <NUM>-<NUM> in the array <NUM> changes from LOW to HIGH. After the second rotation, the output of the second sensor <NUM>-<NUM> changes from LOW to HIGH. After the third complete rotation, the output of the third sensor <NUM>-<NUM> changes from LOW to HIGH and so on until the fifth complete rotation at which point the output of the fifth sensor <NUM>-<NUM> changes from LOW to HIGH. It will thus be appreciated that the signals output by the sensors of the array <NUM> can be used to determine the number of complete rotations.

The code <NUM> read by the sensing arrangement <NUM> is then used by the circuitry <NUM> to determine the extent of any partial rotations of the number sleeve <NUM> number sleeve <NUM>. The determined extent of partial rotation of the number sleeve <NUM> is then combined with the determined number of complete rotations to determine the currently dialled dose of the drug delivery device <NUM>.

<FIG> is a simplified schematic block diagram of a sensor device <NUM> according to various embodiments. As described above, the sensor device <NUM> comprises the array <NUM> of optical sensors <NUM>-<NUM> to <NUM>-<NUM> which are configured to output signals to the circuitry <NUM>. The device also <NUM> comprises the sensing arrangement <NUM> which is configured to output signals indicative of the encoded information to the circuitry <NUM>.

The circuitry <NUM> may be of any suitable composition and may comprise any combination of one or more processors and/or microprocessors <NUM> (for simplicity, hereafter referred to as "the at least one processor") suitable for causing the functionality described herein to be performed. The circuitry <NUM> may additionally or alternatively comprise any combination of one or more hardware-only components such as ASICs, FPGAs etc. (which are not shown in <FIG>).

The circuitry <NUM> may further comprise any combination of one or more non-transitory computer readable memory media <NUM>, such as one or both of ROM and RAM, which is coupled to the at least one processor <NUM>. The memory <NUM> may have computer-readable instructions 211A stored thereon. The computer readable instructions <NUM>, when executed by the at least one processor <NUM> may cause the sensor device <NUM> to perform the functionality described in this specification, such as controlling operation of the array <NUM> and sensing arrangement <NUM> and interpreting the signals received therefrom.

The sensing arrangement <NUM> comprises at least a light source <NUM>-<NUM> and a photosensor <NUM>-<NUM>. The light source <NUM>-<NUM> is for illuminating the encoded information <NUM> that is visible within the further window <NUM> formed in the device housing <NUM>. The photosensor <NUM>-<NUM> is configured read the encoded information by detecting an image (which includes the encoded information <NUM>) which is visible to the photosensor (i.e. which underlies the photosensor). The image is detected by detecting the light reflected back from different parts of the surface(s) on which the image is provided. The encoded information <NUM> is then passed to the circuitry <NUM>. The sensing arrangement <NUM> may comprise further non-electrical components, which are not shown on <FIG>. These non-electrical components of the sensing arrangement <NUM> are described with reference to <FIG>.

The sensor device <NUM> may further comprise one or both of a display screen <NUM> (such as an LED or LCD screen) and a data port <NUM>. The display screen <NUM> may be operable under the control of the circuitry <NUM> to display information regarding operation of the drug delivery device <NUM> to the user. For instance, the information determined by the sensor device <NUM> may be displayed to the user. The information determined by the sensor device <NUM> may include the dialled dose. Other information which can be determined by the sensor device <NUM> includes the drug being dispensed, the mode of the drug delivery device <NUM>, <NUM>, and or a history of previously-dispensed doses.

The data port <NUM> may be used to transfer stored information relating to the operation of the drug delivery device <NUM> from the memory <NUM> to a remote device such a PC, tablet computer, or smartphone. Similarly, new software/firmware may be transferred to the sensor device via the data port <NUM>. The data port <NUM> may be a physical port such as a USB port or may be a virtual, or wireless, port such as an IR, WiFi or Bluetooth transceiver.

The sensor device <NUM> may further comprise a removable or permanent (preferably rechargeable with e.g. photovoltaic cells) battery <NUM> for powering the other components of the device <NUM>. Instead of the battery <NUM>, a photovoltaic or capacitor power source may be used. Other electrical components which are not shown in <FIG>, but which may nonetheless be included in the sensor device <NUM> include a trigger buffer <NUM>-<NUM>, a regulator <NUM>-<NUM>, a voltage suppressor <NUM>-<NUM> and a charger chip <NUM>-<NUM>, for charging the rechargeable battery if present.

<FIG> shows an example of a physical arrangement of the components of the sensor device of <FIG>. The sensors <NUM>-<NUM> to <NUM>-<NUM> of the array <NUM> are arranged on a first surface of a PCB <NUM>-<NUM> in a way that is determined by the shape of the visible path of the movable element <NUM> with which the sensor device <NUM> is designed to be used. In the examples described herein, the visible path is linear and, consequently, the optical sensors <NUM>-<NUM> to <NUM>-<NUM> of the array <NUM> are linearly arranged on the PCB <NUM>-<NUM>. When the sensor device <NUM> is attached to the drug delivery device <NUM>, <NUM>, the first surface of the PCB <NUM>-<NUM> faces the at least one window 13A, 13B of the drug delivery device <NUM>, <NUM>.

One or more of: the light source <NUM>-<NUM> of the sensor arrangement <NUM>, the at least one processor <NUM>, the memory <NUM>, the charger chip <NUM>-<NUM>, the voltage suppressor <NUM>-<NUM>, the regulator <NUM>-<NUM> and the trigger buffer <NUM>-<NUM> may also be provided on the first surface of the PCB <NUM>-<NUM>.

The screen <NUM> is provided on the opposite side of the PCB to the <NUM>-<NUM> to the array <NUM> of optical sensors <NUM>-<NUM> to <NUM>-<NUM>, such that it is visible to the user when the sensor device <NUM> is attached to the drug delivery device <NUM>, <NUM>. The sensor device <NUM> may be configured so as to extend over the entire area of the at least one window 13A, 13B such that the at least one window 13A, 13B is not visible to the user when the sensor device <NUM> is attached.

The photosensor or detector <NUM>-<NUM> of the sensing arrangement <NUM> may not be provided on the PCB <NUM>-<NUM>. Instead, the photosensor <NUM>-<NUM> may be provided on a support element <NUM>-<NUM> which extends from the PCB <NUM>-<NUM>. In the example of <FIG>, the support element <NUM>-<NUM> extends perpendicularly from the PCB, such that when it is attached to the drug delivery device <NUM>, it wraps around a side of the device <NUM>.

As will be appreciated the exact physical arrangement of the components within the sensor device <NUM> may not be crucial as long as, when the sensor device <NUM> is attached to the drug delivery device <NUM>, the array <NUM> of sensors is aligned parallel to the extension of the gauge element <NUM> and parallel to the travel path of the gauge element <NUM>.

For the sensing arrangement <NUM>, it may also be important that the photosensor <NUM>-<NUM> of the sensing arrangement <NUM> is positioned so as to overlie the first aperture <NUM> formed in the housing <NUM> of the drug delivery device <NUM>.

The sensing arrangement <NUM>, in this example, further comprises a light guide <NUM>-<NUM> for guiding the light from the light source <NUM>-<NUM> to the first aperture <NUM> of the drug delivery device <NUM>. The sensing arrangement <NUM> also comprises a lens array <NUM>-<NUM> for focussing on the photosensor <NUM>-<NUM> the light reflected back from the surface(s) underlying the photosensor <NUM>-<NUM>. Put another way, the lens array <NUM>-<NUM> is configured to focus the image, which is provided on the surface(s) underlying the photosensor <NUM>-<NUM>, on to the photosensor <NUM>-<NUM>.

<FIG> shows the sensor device <NUM>, without a housing, in position on the drug delivery device <NUM>, <NUM>. Although not shown, the sensor device <NUM> may be configured to be removably attached in position on the drug delivery device <NUM>. For instance, the housing (not shown) of the sensor device <NUM> may include a coupling mechanism for securely affixing the sensor device <NUM> to the drug delivery device <NUM>. Alternatively, any other means for securing the sensor device <NUM> in position on the drug delivery device <NUM> may be used.

As discussed above, the encoded information that is read by the sensing arrangement <NUM> may include a portion of the non-visible code <NUM> for enabling the circuitry <NUM> to determine the rotational orientation of the number sleeve <NUM>. However, in some embodiments, other operational information may alternatively or additionally be included in the code <NUM> that is read by the sensing arrangement. For instance, the code <NUM> may include a portion for indicating the drug that is being delivered. This can be seen in <FIG> which show examples of two different views of the encoded information that may be visible to the photosensor <NUM>-<NUM> of the sensing arrangement <NUM>. At least part of the code information <NUM>, e.g. some code lines <NUM>, <NUM>, <NUM> or code columns <NUM>, <NUM>, <NUM> may be visible through the first aperture <NUM> of the drug delivery device <NUM>.

The code <NUM> may further include a portion, such mode indicator <NUM>, a particular code line <NUM>, <NUM>, <NUM> or a particular code column <NUM>, <NUM>, <NUM> for indicating an actual operation mode of the drug delivery device <NUM>, e.g. a dialling mode or delivery mode. When the device <NUM> is in the dialling mode, a mode indicator <NUM> is not part of the encoded information and when the device in the delivery mode, the mode indicator <NUM> is part of the encoded information <NUM>.

Consequently, by determining whether or not the mode indicator <NUM> is present in the encoded information <NUM>, the circuitry <NUM> can determine the mode of the device <NUM>.

The mode indicator <NUM> may be provided on an internal element that is caused to move in response to actuation of the drug delivery mechanism (for instance by pushing the button <NUM>). The movable internal element and drug delivery mechanism are together configured such that actuation of the drug delivery mechanism thereby to switch from dialling mode to delivery mode, causes the mode indicator <NUM> to become visible (or to disappear from) within the first aperture <NUM>. An example of such an internal movable element <NUM> is shown in <FIG> and is a "locking arm". When situated within the drug delivery device <NUM>, the locking arm <NUM> is configured to move from a first position to a second position in response to actuation of the drug delivery mechanism. The locking arm <NUM> may be further configured to move from the second position back to the first position in response to subsequent actuation of the drug dialling mechanism. The mode indicator <NUM> is only visible through the aperture <NUM> when the locking arm <NUM> is in one of the first and second positions. In this way, the sensor device <NUM> is able to determine the mode of the drug delivery device <NUM> to which it is attached.

In some embodiments, the sensor device <NUM> is configured to store a history of dispensed drug doses. This may be carried out by storing information indicative of the currently dialled dose, when a change from dialling mode to delivery mode is detected based on the mode indicator <NUM>. A timestamp indicative of a time at which the mode change occurred may also be stored in association with the information indicative of the dose. In addition or alternatively, information indicative of the type of the dispensed drug, which is determined based on the drug indication code portion may be stored in association with the dose information. This may be repeated each time a dose of a drug is dispensed.

Although the drug delivery devices described herein include two windows 13A, 13B through which the movable gauge element <NUM> is visible, it will be appreciated that sensor devices <NUM> according to embodiments of the invention may be used with drug delivery devices <NUM> which include only one of these windows 13A, 13B.

Claim 1:
A drug delivery device (<NUM>) for setting and injecting of a dose of an injectable medicament, the drug delivery device comprising:
- an elongated housing (<NUM>) extending along a longitudinal axis (z) and having a sidewall (12a) with at least a first aperture (<NUM>),
- at least one number sleeve (<NUM>) rotatably supported inside the housing (<NUM>) and comprising an outer surface (<NUM>), wherein a first portion (<NUM>) of the outer surface (<NUM>) is visible through the first aperture (<NUM>) and wherein the outer surface (<NUM>) comprises a second portion (<NUM>) with numerous visible symbols (<NUM>) extending along a helical pattern (<NUM>), characterized in that the number sleeve (<NUM>) comprises a non-visible code (<NUM>) in the region of the first portion (<NUM>), wherein the non-visible code (<NUM>) is invisible to a human eye and is reflective in the UV spectral range or in the IR spectral range and wherein the first portion (<NUM>) and the second portion (<NUM>) overlap at least in sections.