Supplemental device for attachment to an injection device

A supplemental device for attachment to an injection device including a dosage window covering a sleeve on which dose values are marked is provided. The supplemental device comprises: a main body; an arrangement for supporting the main body of the supplemental device in a predetermined positional relationship with the injection device; a transparent protection window located at a surface of the main body that is aligned with the dosage window of the injection pen when in use; and a sensor arrangement supported in the main body and having a sensor directed at the protection window. The protection window has an optical power. The protection window may be a cylindrical lens or a toric lens.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a U.S. National Phase Application pursuant to 35 U.S.C. § 371 of International Application No. PCT/EP2014/058322 filed Apr. 22, 2014. The entire disclosure contents of these applications are herewith incorporated by reference into the present application.

FIELD OF INVENTION

The present invention relates to a supplemental device for attachment to an injection device.

BACKGROUND

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-1 and type-2 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 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 WO 2011/117212 to provide a supplementary device comprising a mating unit for releasably attaching the device to an injection 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 dialed into the injection device.

SUMMARY

A first aspect of the invention provides a supplemental device configured for attachment to an injection the supplemental device comprising:

a main body;

an arrangement for supporting the main body of the supplemental device in a predetermined positional relationship with the injection device;

a transparent protection window located at a surface of the main body; and

a sensor arrangement supported in the main body and having a sensor directed at the protection window,

wherein the protection window is configured as a cylindrical lens or a toric lens with an optical power.

This arrangement can correct for pin cushion distortion provided by the sensor arrangement, the distance between the sensor arrangement and the dosage window and/or the curved shape of a sleeve that is viewable through the protection window. Moreover, this can be achieved through a simple and inexpensive arrangement.

The protection window may be configured as a toric lens, or it may be configured as a cylindrical lens. A cylindrical lens may be easier to produce. Both may have similar ability to correct pin cushion distortion.

A first portion of the protection window may be configured as a cylindrical or toric lens and wherein a second portion of the protection window has a different optical power to the first portion. This can allow part of the protection window that is used in the optical imaging system to have the optical power needed to reduce pin cushion distortion whilst allowing the second portion not to be required to have the optical power. The second portion may be used for illuminating the sleeve visible through the dosage window and/or for mechanical support for the first portion.

The supplemental device may comprise an illumination arrangement comprising one or more sources of light, each of the one or more sources of light being directed at the protection window. This can improve operation of the sensor arrangement. The protection window can assist in illuminating the sleeve visible through the dosage window.

The supplemental device may comprise an illumination arrangement comprising one or more sources of light, each of the one or more sources of light being directed at the protection window, wherein a first portion of the protection window may be configured as a cylindrical or toric lens, wherein a second portion of the protection window has a different optical power to the first portion. The first portion of the protection window may be in the optical path between the sensor arrangement and the dosage window of the injection pen when the device is in use The second portion of the protection window may be not in the optical path between the sensor arrangement and the dosage window of the injection pen when the device is in use. The second portion of the protection window may be in the optical path between the illumination arrangement and the dosage window of the injection pen when the device is in use.

The supplemental device may comprise an illumination arrangement comprising two or more sources of light, each of the two or more sources of light being directed at the protection window, wherein the two or more sources of light are located on opposite sides of the sensor arrangement, wherein a central portion of the protection window may be configured as a cylindrical or toric lens, wherein a periphery portion of the protection window has a different optical power to the central portion, wherein the central portion of the protection window may be in the optical path between the sensor arrangement and the dosage window of the injection pen when the device is in use, and wherein the periphery portion of the protection window may be not in the optical path between the sensor arrangement and the dosage window of the injection pen when the device is in use but may be in the optical path between the illumination arrangement and the dosage window of the injection pen when the device is in use.

The transparent protection window may be formed of optical plastic. This can allow the transparent protection window to be provided inexpensively.

The transparent protection window may be provided with an anti-reflective coating on at least one surface thereof. This can improve the optical imaging arrangement and provide more reliable reading of a sleeve visible through the dosage window. The anti-reflective coating may comprise plural dielectric layers. This can remove reflexes effectively in a stable arrangement. The anti-reflective coating may comprise between three and five dielectric layers.

The protection window may be sealed to the main body so as to prevent the ingress of material into the supplemental device around the protection window. This can avoid the need for a separate sealing arrangement.

Another aspect of the invention provides a system comprising a supplemental device as above and an injection device. Here, a surface of the protection window that is furthest from the sensor arrangement may lie on a curved surface of an imaginary cylinder having an axis coincident with a longitudinal axis of the injection device and the surface of the protection window that is furthest from the sensor arrangement may lie in close proximity with a dosage window of the injection device when the supplemental device is installed on the injection device. This can contribute to a compact arrangement for the supplemental device.

A second aspect of the invention provides a supplemental device for attachment to an injection device including a dosage window covering a sleeve on which dose values are marked, the supplemental device comprising:

a main body;

an arrangement for supporting the main body of the supplemental device in a predetermined positional relationship with the injection device;

a transparent protection window located at a surface of the main body that is aligned with the dosage window of the injection pen when in use; and

a sensor arrangement supported in the main body and having a sensor directed at the protection window,

wherein the protection window has an optical power.

This arrangement can correct for pin cushion distortion provided by the sensor arrangement, the distance between the sensor arrangement and the dosage window and/or the curved shape of a sleeve that is viewable through the protection window. Moreover, this can be achieved through a simple and inexpensive arrangement.

The protection window may be configured as a toric lens, or it may be configured as a cylindrical lens. A cylindrical lens may be easier to produce. Both may have similar ability to correct pin cushion distortion.

A first portion of the protection window may have the optical power and a second portion of the protection window may have a different optical power to the first portion. This can allow part of the protection window that is used in the optical imaging system to have the optical power needed to reduce pin cushion distortion whilst allowing the second portion not to be required to have the optical power. The second portion may be used for illuminating the sleeve visible through the dosage window and/or for mechanical support for the first portion.

The supplemental device may comprise an illumination arrangement comprising one or more sources of light, each of the one or more sources of light being directed at the protection window. This can improve operation of the sensor arrangement. The protection window can assist in illuminating the sleeve visible through the dosage window.

The supplemental device may comprise an illumination arrangement comprising one or more sources of light, each of the one or more sources of light being directed at the protection window, wherein a first portion of the protection window has the optical power, wherein a second portion of the protection window has a different optical power to the first portion, wherein the first portion of the protection window may be in the optical path between the sensor arrangement and the dosage window of the injection pen when the device is in use, and wherein the second portion of the protection window may be not in the optical path between the sensor arrangement and the dosage window of the injection pen when the device is in use but may be in the optical path between the illumination arrangement and the dosage window of the injection pen when the device is in use.

The supplemental device may comprise an illumination arrangement comprising two or more sources of light, each of the two or more sources of light being directed at the protection window, wherein the two or more sources of light are located on opposite sides of the sensor arrangement, wherein a central portion of the protection window has the optical power, wherein a periphery portion of the protection window has a different optical power to the central portion, wherein the central portion of the protection window may be in the optical path between the sensor arrangement and the dosage window of the injection pen when the device is in use, and wherein the periphery portion of the protection window may be not in the optical path between the sensor arrangement and the dosage window of the injection pen when the device is in use but may be in the optical path between the illumination arrangement and the dosage window of the injection pen when the device is in use.

The transparent protection window may be formed of optical plastic. This can allow the transparent protection window to be provided inexpensively.

The transparent protection window may be provided with an anti-reflective coating on at least one surface thereof. This can improve the optical imaging arrangement and provide more reliable reading of a sleeve visible through the dosage window. The anti-reflective coating may comprise plural dielectric layers. This can remove reflexes effectively in a stable arrangement. The anti-reflective coating may comprise between three and five dielectric layers.

The protection window may be sealed to the main body so as to prevent the ingress of material into the supplemental device around the protection window. This can avoid the need for a separate sealing arrangement.

Another aspect of the invention provides a system comprising the supplemental device and an injection device. Here, a surface of the protection window that is furthest from the sensor arrangement may lie on a curved surface of an imaginary cylinder having an axis coincident with a longitudinal axis of the injection device and the surface of the protection window that is furthest from the sensor arrangement may lie in close proximity with a dosage window of the injection device when the supplemental device is installed on the injection device. This can contribute to a compact arrangement for the supplemental device.

DETAILED DESCRIPTION

In the following, embodiments of the present invention will be described with reference to an insulin injection device. The present invention is however not limited to such application and may equally well be deployed with injection devices that eject other medicaments, or with other types of medical devices.

FIG. 1ais an exploded view of an injection device1, which may for instance represent Sanofi's Solostar (R) insulin injection pen.

The injection device1ofFIG. 1ais a pre-filled, disposable injection pen that comprises a housing10and contains an insulin container14, to which a needle15can be affixed. The needle is protected by an inner needle cap16and an outer needle cap17, which in turn can be covered by a cap18. An insulin dose to be ejected from injection device1can be selected by turning the dosage knob12, and the selected dose is then displayed via dosage window13, for instance in multiples of so-called International Units (IU), wherein one IU is the biological equivalent of about 45.5 micrograms of pure crystalline insulin ( 1/22 mg). An example of a selected dose displayed in dosage window13may for instance be 30 IUs, as shown inFIG. 1a. It should be noted that the selected dose may equally well be displayed differently. A label (not shown) is provided on the housing10. The label includes information about the medicament included within the injection device, including information identifying the medicament. The information identifying the medicament may be in the form of text. The information identifying the medicament may also be in the form of a colour. The information identifying the medicament may also be encoded into a barcode, QR code or the like. The information identifying the medicament may also be in the form of a black and white pattern, a colour pattern or shading.

Turning the dosage knob12causes a mechanical click sound to provide acoustical feedback to a user. The numbers displayed in dosage window13are printed on a sleeve that is contained in housing10and mechanically interacts with a piston in insulin container14. When needle15is stuck into a skin portion of a patient, and then injection button11is pushed, the insulin dose displayed in display window13will be ejected from injection device1. When the needle15of injection device1remains for a certain time in the skin portion after the injection button11is pushed, a high percentage of the dose is actually injected into the patient's body. Ejection of the insulin dose also causes a mechanical click sound, which is however different from the sounds produced when using dosage knob12.

Injection device1may be used for several injection processes until either insulin container14is empty or the expiration date of injection device1(e.g. 28 days after the first use) is reached.

Furthermore, before using injection device1for the first time, it may be necessary to perform a so-called “prime shot” to remove air from insulin container14and needle15, for instance by selecting two units of insulin and pressing injection button11while holding injection device1with the needle15upwards.

For simplicity of presentation, in the following, it will be exemplarily assumed that the ejected doses substantially correspond to the injected doses, so that, for instance when making a proposal for a dose to be injected next, this dose equals the dose that has to ejected by the injection device. Nevertheless, differences (e.g. losses) between the ejected doses and the injected doses may of course be taken into account.

FIG. 1bis a close-up of the end of the injection device1. This FIG. shows a locating rib70that is located between the viewing window13and the dosage knob12.

FIG. 2ais a schematic illustration of an embodiment of a supplementary device2to be releasably attached to injection device1ofFIG. 1a. Supplementary device2comprises a housing20with a mating unit configured and embrace the housing10of injection device1ofFIG. 1a, so that supplementary device2sits tightly on housing10of injection device1, but is nevertheless removable from injection device1, for instance when injection device1is empty and has to be replaced.FIG. 2ais highly schematic, and details of the physical arrangement are described below with reference toFIG. 2b.

Supplementary device2contains optical and acoustical sensors for gathering information from injection device1. At least a part of this information, for instance a selected dose (and optionally a unit of this dose), is displayed via display unit21of supplementary device2. The dosage window13of injection device1is obstructed by supplementary device2when attached to injection device1.

Supplementary device2further comprises three user input transducers, illustrated schematically as a button22. These input transducers22allow a user to turn on/off supplementary device2, to trigger actions (for instance to cause establishment of a connection to or a pairing with another device, and/or to trigger transmission of information from supplementary device2to another device), or to confirm something.

FIG. 2bis a schematic illustration of a second embodiment of a supplementary device2to be releasably attached to injection device1ofFIG. 1a. Supplementary device2comprises a housing20with a mating unit configured and embrace the housing10of injection device1ofFIG. 1a, so that supplementary device2sits tightly on housing10of injection device1, but is nevertheless removable from injection device1.

Information is displayed via display unit21of supplementary device2. The dosage window13of injection device1is obstructed by supplementary device2when attached to injection device1.

Supplementary device2further comprises three user input buttons or switches. A first button22is a power on/off button, via which the supplementary device2may for instance be turned on and off. A second button33is a communications button. A third button34is a confirm or OK button. The buttons22,33,34may be any suitable form of mechanical switch. These input buttons22,33,34allow a user to turn on/off supplementary device2, to trigger actions (for instance to cause establishment of a connection to or a pairing with another device, and/or to trigger transmission of information from supplementary device2to another device), or to confirm something.

FIG. 2cis a schematic illustration of a third embodiment of a supplementary device2to be releasably attached to injection device1ofFIG. 1a. Supplementary device2comprises a housing20with a mating unit configured and embrace the housing10of injection device1ofFIG. 1a, so that supplementary device2sits tightly on housing10of injection device1, but is nevertheless removable from injection device1.

Information is displayed via display unit21of the supplementary device2. The dosage window13of injection device1is obstructed by supplementary device2when attached to injection device1.

Supplementary device2further comprises a touch-sensitive input transducer35. It also comprises a single user input button or switch22. The button22is a power on/off button, via which the supplementary device2may for instance be turned on and off. The touch sensitive input transducer35can be used to trigger actions (for instance to cause establishment of a connection to or a pairing with another device, and/or to trigger transmission of information from supplementary device2to another device), or to confirm something.

FIGS. 3A and 3bshow possible distributions of functions among devices when using a supplementary device (such as the supplementary devices ofFIGS. 2aand 2b) together with an injection device.

In constellation4ofFIG. 3a, the supplementary device41(such as the supplementary devices ofFIGS. 2aand 2b) determines information from injection device40, and provides this information (e.g. type and/or dose of the medicament to be injected) to a blood glucose monitoring system42(e.g. via a wired or wireless connection).

Blood glucose monitoring system42(which may for instance be embodied as desktop computer, personal digital assistant, mobile phone, tablet computer, notebook, netbook or ultrabook) keeps a record of the injections a patient has received so far (based on the ejected doses, for instance by assuming that the ejected doses and the injected doses are the same, or by determining the injected doses based on the ejected doses, for instance be assuming that a pre-defined percentage of the ejected dose is not completely received by the patient). Blood glucose monitoring system42may for instance propose a type and/or dose of insulin for the next injection for this patient. This proposal may be based on information on one or more past injections received by the patient, and on a current blood glucose level, that is measured by blood glucose meter43and provided (e.g. via a wired or wireless connection) to blood glucose monitoring system42. Therein, blood glucose meter43may be embodied as a separate device that is configured to receive a small blood probe (for instance on a carrier material) of a patient and to determine the blood glucose level of the patient based on this blood probe. Blood glucose meter43may however also be a device that is at least temporarily implanted into the patient, for instance in the patient's eye or beneath the skin.

FIG. 3bis a modified constellation4′ where the blood glucose meter43ofFIG. 3ahas been included into blood glucose monitoring system42ofFIG. 3a, thus yielding the modified blood glucose monitoring system42′ ofFIG. 3b. The functionalities of injection device40and supplementary device41ofFIG. 3aare not affected by this modification. Also the functionality of blood glucose monitoring system42and blood glucose meter43combined into blood glucose monitoring system42′ are basically unchanged, apart from the fact that both are now comprised in the same device, so that external wired or wireless communication between these devices is no longer necessary. However, communication between blood glucose monitoring system42and blood glucose meter43takes place within system42′.

FIG. 4shows a schematic view of the supplementary device2ofFIG. 2ain a state where it is attached to injection device1ofFIG. 1a.

With the housing20of supplementary device2, a plurality of components are comprised. These are controlled by a processor24, which may for instance be a microprocessor, a Digital Signal Processor (DSP), Application Specific Integrated Circuit (ASIC), Field Programmable Gate Array (FPGA) or the like. Processor24executes program code (e.g. software or firmware) stored in a program memory240, and uses a main memory241, for instance to store intermediate results. Main memory241may also be used to store a logbook on performed ejections/injections. Program memory240may for instance be a Read-Only Memory (ROM), and main memory may for instance be a Random Access Memory (RAM).

In embodiments such as those shown inFIG. 2b, processor24interacts with a first button22, via which supplementary device2may for instance be turned on and off. A second button33is a communications button. The second button may be used to trigger establishment of a connection to another device, or to trigger a transmission of information to another device. A third button34is a confirm or OK button. The third button34can be used to acknowledge information presented to a user of supplementary device2. In embodiments such as those shown inFIG. 2c, two of the buttons33,34may be omitted. Instead, one or more capacitive sensors or other touch sensors are provided.

Processor24controls a display unit21, which is presently embodied as a Liquid Crystal Display (LCD). Display unit21is used to display information to a user of supplementary device2, for instance on present settings of injection device1, or on a next injection to be given. Display unit21may also be embodied as a touch-screen display, for instance to receive user input.

Processor24also controls an optical sensor25, embodied as an Optical Character Recognition (OCR) reader, that is capable of capturing images of the dosage window13, in which a currently selected dose is displayed (by way of numbers printed on the sleeve19contained in injection device1, which numbers are visible through the dosage window13). OCR reader25is further capable of recognizing characters (e.g. numbers) from the captured image and to provide this information to processor24. Alternatively, unit25in supplementary device2may only be an optical sensor, e.g. a camera, for capturing images and providing information on the captured images to processor24. Then processor24is responsible for performing OCR on the captured images.

Processor24also controls light-sources such as light emitting diodes (LEDs)29to illuminate the dosage window13, in which a currently selected dose is displayed. A diffuser may be used in front of the light-sources, for instance a diffuser made from a piece of acrylic glass. Furthermore, the optical sensor may comprise a lens system, for instance including two aspheric lenses. The magnification ratio (image size to object size ratio) may be smaller than 1. The magnification ratio may be in the range of 0.05 to 0.5. In one embodiment the magnification ration may be 0.15.

Processor24further controls a photometer26, that is configured to determine an optical property of the housing10of injection device1, for example a colour or a shading. The optical property may only be present in a specific portion of housing10, for example a colour or colour coding of sleeve19or of an insulin container comprised within injection device1, which colour or colour coding may for instance be visible through a further window in housing10(and/or in sleeve19). Information on this colour is then provided to processor24, which may then determine the type of injection device1or the type of insulin contained in injection device1(e.g. SoloStar Lantus with purple colour and SoloStar Apidra with blue colour). Alternatively, a camera unit may be used instead of photometer26, and an image of the housing, sleeve or insulin container may then be provided to processor24to determine the colour of the housing, sleeve or insulin container by way of image processing. Further, one or more light sources may be provided to improve reading of photometer26. The light source may provide light of a certain wavelength or spectrum to improve colour detection by photometer26. The light source may be arranged in such a way that unwanted reflections, for example by dosage window13, are avoided or reduced. In an example embodiment, instead of or in addition to photometer26, a camera unit may be deployed to detect a code (for instance a bar code, which may for instance be a one- or two-dimensional bar code) related to the injection device and/or the medicament contained therein. This code may for instance be located on the housing10or on a medicament container contained in injection device1, to name but a few examples. This code may for instance indicate a type of the injection device and/or the medicament, and/or further properties (for instance a expiration date).

Processor24further controls (and/or receives signals from) an acoustic sensor27, which is configured to sense sounds produced by injection device1. Such sounds may for instance occur when a dose is dialed by turning dosage knob12and/or when a dose is ejected/injected by pressing injection button11, and/or when a prime shot is performed. These actions are mechanically similar but nevertheless sound differently (this may also be the case for electronic sounds that indicate these actions). Either the acoustic sensor27and/or processor24may be configured to differentiate these different sounds, for instance to be able to safely recognize that an injection has taken place (rather than a prime shot only).

Processor24further controls an acoustical signal generator23, which is configured to produce acoustical signals that may for instance be related to the operating status of injection device1, for instance as feedback to the user. For example, an acoustical signal may be launched by acoustical signal generator23as a reminder for the next dose to be injected or as a warning signal, for instance in case of misuse. Acoustical signal generator may for instance be embodied as a buzzer or loudspeaker. In addition to or as an alternative to acoustical signal generator23, also a haptic signal generator (not shown) may be used to provide haptic feedback, for instance by way of vibration.

Processor24controls a wireless unit28, which is configured to transmit and/or receive information to/from another device in a wireless fashion. Such transmission may for instance be based on radio transmission or optical transmission. In some embodiments, the wireless unit28is a Bluetooth transceiver. Alternatively, wireless unit28may be substituted or complemented by a wired unit configured to transmit and/or receive information to/from another device in a wire-bound fashion, for instance via a cable or fibre connection. When data is transmitted, the units of the data (values) transferred may be explicitly or implicitly defined. For instance, in case of an insulin dose, always International Units (IU) may be used, or otherwise, the used unit may be transferred explicitly, for instance in coded form.

Processor24receives an input from a pen detection switch30, which is operable to detect whether the pen1is present, i.e. to detect whether the supplementary device2is coupled to the injection device1.

A battery32powers the processor24and other components by way of a power supply31.

The supplementary device2ofFIG. 4is thus capable of determining information related to a condition and/or use of injection device1. This information is displayed on the display21for use by the user of the device. The information may be either processed by supplementary device2itself, or may at least partially be provided to another device (e.g. a blood glucose monitoring system).

FIGS. 5a-5care flowcharts of embodiments of methods according to the present invention. These methods may for instance be performed by processor24of supplementary device2(seeFIGS. 2band4), but also by a processor of supplementary device3ofFIG. 2b, and may for instance be stored in program memory240of supplementary device2, which may for instance take the shape of tangible storage medium60ofFIG. 6.

FIG. 5ashows method steps that are performed in scenarios as shown inFIGS. 3aand 3b, where information read by supplementary device41from injection device40is provided to blood glucose monitoring system42or42′ without receiving information back from blood glucose monitoring system42or42′.

The flowchart500starts for instance when the supplementary device is turned on or is otherwise activated. In a step501, a type of medicament, for example insulin, provided by the injection device is determined, for instance based on colour recognition or based on recognition of a code printed on injection device or a component thereof as already described above. Detection of the type of medicament may not be necessary if a patient always takes the same type of medicament and only uses an injection device with this single type of medicament. Furthermore, determination of the type of medicament may be ensured otherwise (e.g. by the key-recess pair shown inFIG. 4that the supplementary device is only useable with one specific injection device, which may then only provide this single type of medicament).

In a step502, a currently selected dose is determined, for instance by OCR of information shown on a dosage window of injection device as described above. This information is then displayed to a user of the injection device in a step503.

In a step504, it is checked if an ejection has taken place, for instance by sound recognition as described above. Therein, a prime shot may be differentiated from an actual injection (into a creature) either based on respectively different sounds produced by the injection device and/or based on the ejected dose (e.g. a small dose, for instance less than a pre-defined amount of units, e.g. 4 or 3 units, may be considered to belong to a prime shot, whereas larger doses are considered to belong to an actual injection).

If an ejection has taken place, the determined data, i.e. the selected dose and—if applicable—the type of medicament (e.g. insulin), is stored in the main memory241, from where it may later be transmitted to another device, for instance a blood glucose monitoring system. If a differentiation has been made concerning the nature of the ejection, for instance if the ejection was performed as a prime shot or as an actual injection, this information may also be stored in the main memory241, and possibly later transmitted. In the case of an injection having been performed, at step505the dose is displayed on the display21. Also displayed is a time since the last injection which, immediately after injection, is 0 or 1 minute. The time since last dose may be displayed intermittently. For instance, it may be displayed alternately with the name or other identification of the medicament that was injected, e.g. Apidra or Lantus.

If ejection was not performed at step504, steps502and503are repeated.

After display of the delivered dose and time data, the flowchart500terminates.

FIG. 5bshows in more detail exemplary method steps that are performed when the selected dose is determined based on the use of optical sensors only. For instance, these steps may be performed in step502ofFIG. 5a.

In a step901, a sub-image is captured by an optical sensor such as optical sensor25of supplementary device2. The captured sub-image is for instance an image of at least a part of the dosage window13of injection device1, in which a currently selected dose is displayed (e.g. by way of numbers and/or a scale printed on the sleeve19of injection device1, which is visible through the dosage window13). For instance, the captured sub-image may have a low resolution and/or only show a part of the part of sleeve19which is visible through dosage window13. For instance, the captured sub-image either shows the numbers or the scale printed on the part of sleeve19of injection device1which is visible through dosage window13. After capturing an image, it is, for instance, further processed as follows:Division by a previously captured background image;Binning of the image(s) to reduce the number of pixels for further evaluations;Normalization of the image(s) to reduce intensity variations in the illumination;Sheering of the image(s); and/orBinarization of the image(s) by comparing to a fixed threshold.

Several or all of these steps may be omitted if applicable, for instance if a sufficiently large optical sensor (e.g. a sensor with sufficiently large pixels) is used.

In a step902, it is determined whether or not there is a change in the captured sub-image. For instance, the currently captured sub-image may be compared to the previously captured sub-image(s) in order to determine whether or not there is a change. Therein, the comparison to previously captured sub-images may be limited to the sub-image of the previously captured sub-images that was captured immediately before the current sub-image was captured and/or to the sub-images of the previously captured sub-images that were captured within a specified period of time (e.g. 0.1 seconds) before the current sub-image was captured. The comparison may be based on image analysis techniques such as pattern recognition performed on the currently captured sub-image and on the previously captured sub-image. For instance, it may be analyzed whether the pattern of the scale and/or the numbers visible through the dosage window13and shown in the currently captured sub-image and in the previously captured sub-image is changed. For instance, it may be searched for patterns in the image that have a certain size and/or aspect ratio and these patterns may be compared with previously saved patterns. Steps901and902may correspond to a detection of a change in the captured image.

If it is determined in step902that there is a change in the sub-image, step901is repeated. Otherwise in a step903, an image is captured by an optical sensor such as optical sensor25of supplementary device2. The captured image is for instance an image of the dosage window13of injection device1, in which a currently selected dose is displayed (e.g. by way of numbers and/or a scale printed on the sleeve19of injection device1, which is visible through the dosage window13). For instance, the captured image may have a resolution being higher than the resolution of the captured sub-image. The captured image at least shows the numbers printed on the sleeve19of injection device1which are visible through the dosage window13.

In a step904, optical character recognition (OCR) is performed on the image captured in step903in order to recognize the numbers printed on the sleeve19of injection device1and visible through the dosage window13, because these numbers correspond to the (currently) selected dose. In accord to the recognized numbers, the selected dose is determined, for instance by setting a value representing the selected dose to the recognized numbers.

In a step905, it is determined whether or not there is a change in the determined selected dose and, optionally, whether or not the determined selected dose does not equal zero. For instance, the currently determined selected dose may be compared to the previously determined selected dose(s) in order to determine whether or not there is a change. Therein, the comparison to previously determined selected dose(s) may be limited to the previously determined selected dose(s) that were determined within a specified period of time (e.g. 3 seconds) before the current selected dose was determined. If there is no change in the determined selected dose and, optionally, the determined selected dose does not equal zero, the currently determined selected dose is returned/forwarded for further processing (e.g. to processor24).

Thus, the selected dose is determined if the last turn of the dosage knob12is more than 3 seconds ago. If the dosage knob12is turned within or after these 3 seconds and the new position remains unchanged for more than 3 seconds, this value is taken as the determined selected dose.

FIG. 5cshows in more detail method steps that are performed when the selected dose is determined based on the use of acoustical and optical sensors. For instance, these steps may be performed in step502ofFIG. 5a.

In a step1001, a sound is captured by an acoustical sensor such as acoustical sensor27of supplementary device2.

In a step1002, it is determined whether or not the captured sound is a click sound. The captured sound may for instance be a click sound that occurs when a dose is dialed by turning dosage knob12of injection device1and/or when a dose is ejected/injected by pressing injection button11, and/or when a prime shot is performed. If the captured sound is not a click sound, step1001is repeated. Otherwise in a step1003, an image is captured by an optical sensor such as optical sensor25of supplementary device2. Step1003corresponds to step903of flowchart900.

In a step1004, an OCR is performed on the image captured in step1003. Step1004corresponds to step904of flowchart900.

In a step1005, it is determined whether or not there is a change in the determined selected dose and, optionally, whether or not the determined selected dose does not equal zero. Step1005corresponds to step905of flowchart900.

There might be a slight advantage of the acoustic approach shown inFIG. 5cwhen it comes to power consumption of the supplementary device, because permanently capturing images or sub-images as shown inFIG. 5btypically is more power consuming than listening to an acoustical sensor such as a microphone.

FIG. 6is a schematic illustration of a tangible storage medium600(a computer program product) that comprises a computer program601with program code602. This program code may for instance be executed by processors contained in the supplementary device, for instance processor24of supplementary device2ofFIGS. 2 and 4. For instance, storage medium600may represent program memory240of supplementary device2ofFIG. 4. Storage medium600may be a fixed memory, or a removable memory, such as for instance a memory stick or card.

As described in detail above, embodiments of the present invention allow connection of a standard injection device, in particular an insulin device, with a blood glucose monitoring system in a useful and productive way.

Embodiments of the present invention introduce a supplementary device to allow for this connection, assuming the blood glucose monitoring system has wireless or other communication capabilities. The benefits of providing such a supplementary device have been described, for instance in WO 2011/117212.

The term “drug” or “medicament”, as used herein, means a pharmaceutical formulation containing at least one pharmaceutically active compound, for instance as described in WO 2011/117212.

The mechanical arrangement of the supplemental device2and the manner in which it is attached to the injection device1will now be described with reference toFIGS. 8 to 14.

As is best seen fromFIG. 8, the supplemental device2is attached to the injection pen1close to the dosage knob12with the display21uppermost in the orientation shown (which is the same for all ofFIGS. 8 to 14). The plane of the display21lies generally transverse to the longitudinal axis of the injection device1, and is perpendicular to the page ofFIGS. 8, 9, 10, 12, 13 and 14.

A closure68extends from a shaft59of a hinge, the closure extending underneath the injection pen. The closure68is connected to the supplemental device2on the right side (looking at the injection device1with the injection button closest to the viewer), extends underneath the injection pen1and connects with the supplemental device on the left side thereof.

The supplemental device2of these illustrated embodiments includes two features that contribute to correct alignment of the supplemental device2on the injection device1, and one feature that results in securing of the supplemental device2to the injection device1. The features that contribute to correct alignment of the supplemental device2on the injection device1can be termed alignment arrangements. The features that contribute to securing of the supplemental device2to the injection device1can be termed a securing arrangement.

The correct alignment of the supplemental device2on the injection device1, ensures that the OCR reader25is correctly aligned with the dosage window13. Correct alignment allows correct operation and reliable readings. Ensuring that there can be correct alignment between the supplemental device2and the injection device1in use allows a simpler design for the OCR reader25, in particular because it does not need to be designed to be able to accommodate different alignments between the devices1,2.

The first alignment feature is a locating channel71. The locating channel71is located at the uppermost part of an injection device receiving channel58that is defined between the main body of the supplemental part and the closure68when in the closed position.

The locating channel71is best shown inFIGS. 11aand 11b. From here, it will be seen that the locating channel is formed at the end of the supplemental device that is closest to the dosage knob12when the supplemental device2is fitted to the injection device1.

As is best seen inFIG. 1b, the locating rib70is located between the display window13and the dosage knob12. In this example, the locating rib70extends for the whole of the distance between the display window13and the dosage knob12. In other examples, the locating rib is shorter. The locating rib70is taller at the end that is adjacent the dosage knob12and tapers down to a zero height at the junction with the display window13. As can be seen fromFIG. 1b, the taper of the uppermost edge of the locating rib70is slightly curved. The gradient of the taper is less at the part of the locating rib70that is closest to the dosage knob12and is greater along the locating rib to the location of the display window13. The shape of the locating rib70is such that the gradient continually increases as one moves from the position of the locating rib70that is adjacent to the dosage knob12to the position of the locating rib70that is adjacent the display window13.

The thickness of the locating rib70, the thickness being the dimension that is circumferential to the main body of the injection device1, varies along the length of the locating rib70. The thickness of the locating rib70is greatest at the end adjacent the dosage knob12and is least at the end adjacent the display window13. The thickness of the locating rib70gradually decreases as one moves from the end of the locating rib adjacent the dosage knob12to the end of the locating rib that is adjacent the display window13.

The cross-section of the locating rib, the cross-section being a section taken perpendicular to the longitudinal axis of the injection pen1, is of a rounded triangle. The cross-section of the locating rib70is approximately the same for its entire length, although of course the size varies.

The locating channel71is dimensioned so as to correspond closely to the shape and size of the locating rib70that is present on the injection pen1.

The locating channel71has a size and shape that corresponds closely to the size and shape of the locating rib70. The locating channel71is slightly larger than the locating rib so as to ensure that the locating rib can be located within the locating channel71. When the locating rib70is within the locating channel71, the corresponding sizes ensure that the two features mate together. This assists in ensuring correct positioning of the supplemental device2on the injection device1.

Other features of the supplemental device2and the injection pen1that assist in ensuring correct alignment between the two devices will now be described. As best seen inFIG. 1b, the injection pen1is provided with indents on either side of its body at locations close to the dosage knob12. InFIG. 1b, a left side indent52is shown. A right indent51, which is shown inFIGS. 10 and 12, is located in a corresponding position on the right side of the injection pen1.

The left and right indents51,52are relatively shallow depressions. The indents51,52have sloping sides, that is the sides of the indents51,52are not parallel. Also, they are not radial with respect to the longitudinal axis of the injection pen1. In these embodiments, the slope of the sides of the left and right indents51,52is different for different parts of the indents. In particular, the gradient of the slope of the sides of the indents is less at the part of the indents that is furthest from the display window13and is greatest at the part of the indents51,52that is closest to the display window13. In these examples, the slope of the indents changes between these two extremes, for instance in a linear fashion.

The slope of the sides of the indent may for instance be between 30 and 70 degrees at the part that is furthest from the display window13. The slope may for instance be between 60 and 80 degrees for the part that is closest to the display window13. The greater angle of slope at the part closer to the display window13aids engagement of a face of a protuberance within the indent51,52in such a way as to provide some resistance against removal of the supplemental device2in a direction radial to the longitudinal axis of the injection device1.

As is best seen inFIGS. 10 and 11, the left and right protuberances53,54are shaped to correspond to the shapes of the right and left indents51,52respectively. In this way, the right and left protuberances53,54fit within the right and left indents51,52respectively when the supplementary device2is correctly positioned on the injection pen1. The external dimensions of the right and left protuberances53,54are slightly smaller than the internal dimensions of the right and left indents51,52so as to ensure that the protuberances fit within their respective indent.

In these embodiments, the left and right protuberance52is shaped to correspond closely to the shape of the right indent51. In this way, the right protuberances53fits snugly within the right indent51when the supplementary device2is correctly positioned on the injection pen1. The left protuberance54is shaped similarly to the right protuberance53, although it is less tall. Put another way, it is like the right protuberance53but with the top part missing or cut off. This is the reason for the end face of the left protuberance54having a larger area than the right protuberance53. The different sizes for the protuberances53,54helps the protuberances find engagement within the indents51,52. The right protuberance53can be consider to be a master to the left protuberance, which is a slave.

The right protuberance53is located at the end of the right arm55, which is best shown inFIG. 11b.

As can be seen fromFIG. 11a, the left protuberance54is located at the end of the left arm56.

As can be best seen fromFIG. 10, the right and left arms55,56depend substantially vertically from the body20of the supplementary device2. The right and left arms55,56are thus formed either side of the injection device receiving channel58.

A biasing feature67, in the form of a u-shaped spring, is coupled to each of the right and left arms55,56. The effect of the spring67is to bias the right and left arms into a certain position. The position into which the right and left arms55,56are biased is such that the distance between the innermost surfaces of the right and left protuberances53,54is slightly less than the distance between the bottoms of the right and left indents51,52. The effect of the spring67is to resist movement of the protuberances53,54and the arms55,56, away from one another.

Because the slopes of the sides of the protuberances53,54match the sides of the indents51,52, the sloped sides of the protuberances53,54at the distal ends of the arms55,56is relatively shallow. This assists in sliding the protuberances53,54over the external surface of the body10of the injection pen1as the supplemental device is being fitted. This is best demonstrated with reference toFIGS. 10 and 12.

As is shown inFIG. 10, the supplemental device2is located with respect to the injection pen1such that the ends of the right and left arms55,56, in particular the protuberances53,54, are just touching the housing10of the injection pen1. The protuberances53,54here contact the housing to the left and right sides of the display window13.

The left and right arms55,56are present behind flaps60that depend from the supplemental device2on both the left and right sides. As can be seen fromFIG. 10, the flaps, or protecting walls60, extend slightly further in a downwards direction than the arms. The flaps60are formed of transparent material. This allows a user to be able to view the locations of the arms55,56relative to the indents51,52, which may help them to locate the supplemental device2correctly on the injection device1.FIG. 8shows the location of the left indent52in dotted form, to highlight the location of the arms,55,56as well as the indents51,52, although the arms are not shown in this view.

In order to mate the supplemental device2with the injection device1, the user first arranges the supplemental device2with respect to the injection device1as shown inFIG. 10, and then applies a force downwards on the supplemental device2while at the same time applying a force upwards on the injection device1. This places force on the protuberances53,54, and thus the right and left arms55,56. As the injection device1and the supplemental device2move closer together, the force results in the arms being moved apart, against the resilience of the spring67. This causes the spring67to apply a reaction force, which resists entry of the injection device1into the injection device receiving channel58. However, when the protuberances53,54reach the location on the injection pen1at which they are directly in line with the longitudinal axis of the injection device1, the reaction force supplied by the spring67ceases to increase upon further movement of the injection device1and the supplemental device2together. After this point, the movement of the injection pen1into the injection device receiving channel58is aided by the resilience of the spring67.

After some further movement, the protuberances53,54become aligned with the left and right indent51,52and, due to the resilience of the spring67, become engaged with the indents. Engagement provides haptic and audio feedback as the protuberances53,54click or snap into the indents51,52. The feedback is enhanced by the force provided by the resilience of the spring67. Once the protuberances53,54are mated with the indents51,52, there is significant resistance to further movement of the supplemental device2relative to the injection device1, due in part to the corresponding shapes of the protuberances53,54and the indents51,52and due in part to the biasing together of the arms55,56by the spring67.

If when the supplemental device2and the injection device1are moved together one of the indents51,52is higher than the other, one of the protuberances53,54will engage with the higher one of the indents before the other one of the protuberances reaches the other indent. In this case, the protuberance and indent that first meet become engaged, and present significant resistance to further movement of that protuberance relative to that indent. In this case, the tendency is naturally for the injection device1to be rotated relative to the supplemental device such that the other indent meets the other protuberance. Once the other indent meets the other protuberance, they mate together and considerable resistance is presented against further movement of the injection pen1relative to the supplemental device2. In the scenario in which one of the protuberances meets an indent before the other protuberance meets its respective indent, the experience of the user is such that the injection pen1and the supplemental device2seem to move together initially with little or no rotation. Haptic and audio feedback is then provided when the first protuberance meets the corresponding indent, and after this point the injection device1seems to roll into place within the injection device receiving channel58until the other protuberance is received in the other indent, at which point further haptic and audio feedback is provided to the user.

Once the protuberances53,54are mated in the indent51,52, the injection device1is fully located within the injection device receiving channel58as shown inFIG. 12. Here, it will be seen that the outermost surface of the display window13is generally aligned with a lowermost surface of the upper part of the supplemental device2. This supplemental device2is shaped such that the injection device1fits snugly within the injection device receiving channel58and there are multiple points or areas of contact between the exterior surface of the housing10of the injection device1and the lowermost surface of the supplemental device2when the supplemental device and the injection pen1are in this relative position. Even in the absence of the mating of the protuberances53,54with the indents51,52at this point, the user would notice that there is a natural tendency for the injection pen1to sit at this location within the supplemental device2.

When the supplemental device2is located with respect to the injection pen1such that the right and left protuberances53,54are located within the right and left indents51,52respectively, the locating rib70is engaged within the locating channel71. Correct alignment of the supplemental device2with respect to the injection device1is thus provided in two ways: firstly, by the location of the locating rib70within the locating channel71and secondly by the locating of the protuberances53,54within the indents51,52.

In the event that the user places the supplemental device2onto the injection pen1at a location such that the supplemental device2is slightly at the right of the position shown inFIG. 8, the locating rib70does not fit within the locating channel71. In this case, the supplemental device2is prevented from being located fully over the injection pen1by the locating rib70resting against a surface of the supplemental device2that is in some way distal from the correct location within the locating channel71. However, in this position, the ends of the protuberances53,54have passed the halfway point of the circumference of the housing10of the injection device1and thus the spring67results in the injection device1being biased towards the supplemental device2so as to be located within the injection device receiving channel58. A user would know that the supplemental device2had not mated correctly with the injection pen1because they would not have received any haptic feedback from the mating of the protuberances53,54with the indents51,52. They would also notice that the end of the supplemental device that is closest to the dosage knob12was separated from the injection pen1by a distance greater than the separation of the supplemental device2from the injection pen1at the end of the supplemental device2distal from the dosage knob12. In this situation, the user can engage the supplemental device2and the injection pen1simply by exerting a force against the supplemental device2and the injection pen1such as to move the supplemental device2leftwards in the direction shown inFIG. 8. This can be achieved in a one-handed fashion or in a two-handed fashion. As the supplemental device2and the injection device1move relative to one another, the locating rib and the locating channel become more and more engaged. The spring force provided by the spring67may assist relative movement of the supplemental device2and the injection device1in this manner. As the locating rib70and the locating channel71become more engaged, the end of the supplemental device2that is closest to the dosage knob12moves down towards the injection device1. This movement continues until the locating rib70is completely within the locating channel71, at which point the right and left protuberances53,54also engage with the right and left indents51,52respectively. At this point, haptic feedback is provided by the mating of the protuberances53,54with the indents51,52and the user can determine that the supplemental device2and the injection device1are properly located with respect to one another.

If the user locates the supplemental device onto the injection pen1such that the supplemental device is to the left of the position shown inFIG. 8, mating between the supplemental device2and the injection pen1will not occur. In this case, the locating rib70will not prevent the supplemental device2from being located flat against the injection pen1. A user, noticing this, will know that the supplemental device2is located too far from the dosage knob12. The user can engage the supplemental device2with the injection pen1simply by moving the supplemental device2relative to the injection device1such as to move the supplemental device2rightwards in the direction shown inFIG. 8.

If the locating rib70is aligned with the locating channel71when the end of the locating rib70that is closest to the display window13, the smallest end of the locating rib70will enter the mouth, being the large open end, of the locating channel71. At this stage, the supplemental device still is located against the surface of the injection device1, with the injection device1being fully located within the injection device receiving channel58. Because of the action of the spring67, the injection device1is biased into the injection device receiving channel58against the supplemental device2at this stage.

If the locating rib70and the locating channel71are not exactly aligned, the narrowest end of the locating rib70will engage with a side of the locating channel. Further relative movement of the supplemental device2and the injection device1in a longitudinal direction results in a reactive force being applied between the locating rib and a wall of the locating channel71, biasing the supplemental device2and the injection device1towards being in full alignment. This occurs until the locating rib70is fully engaged within the locating channel71, at which point the right and left protuberances53,54also engage with the right and left indents51,52. At this point, the supplemental device2and the injection device1are fully engaged with one another.

The supplemental device2is provided with a closure68, which has a primary function of clamping the supplemental device2to the injection pen1when the two devices are mated with one another.

As best seen inFIGS. 13 and 14, the closure68has an innermost surface that coincides with the curved surface of an imaginary cylinder. The diameter of the cylinder is the same as the external dimension of the housing10of the injection device1. As such, the closure68forms a snug fit against the lowermost part of the housing10of the injection device1when the supplemental device2is in place on the injection device1.

The closure68is moveable between an open position, shown inFIG. 13, and a closed position, shown inFIG. 14.

As can be seen inFIG. 8, the closure68is located next to the arm protecting walls60, in a direction opposite the arm protecting walls60to the dosage knob12. The closure68has a dimension in a longitudinal axis of the injection pen1that is approximately 60% of the length dimension of the supplemental device2. In other examples, the length of the closure68in a longitudinal direction of the injection pen1may take a value anywhere between 30 and 80% of the length of the supplemental device2, and preferably between 40 and 70% of the length of the supplemental device2.

The material of the closure68has a generally uniform thickness. As such, the external surface of the closure68, that is the surface that is furthest from the longitudinal axis of the injection pen1when the supplemental device2is mated with the injection pen1, is generally cylindrical, or at least takes the form of part of a cylinder.

The closure68is provided with two cutaways72,73. The cutaways72,73extend from an edge of the closure68that is furthest from the shaft59of the hinge formed at the other side of the supplemental device2. The cutaways72,73extend from this edge in a direction that is generally circumferential with respect to the injection pen1. The length of the cutaways is approximately equal to ⅙ or ⅕ of the circumference of the circle on which the closure68generally lies. The cutaways72,73define a tab61. The tab61is connected to the main part of the closure68at a location between the lowermost ends of the cutaways72,73. A free end63of the tab61is located between the uppermost ends of the cutaways72,73. As is best seen inFIG. 9, the free end63of the tab61is curved so as to extend away from the longitudinal axis of the injection pen1by a greater extent at a point that is central between the cutaways72,73. This allows a user better to be able to locate a digit on the free end63of the tab61so as to be able to pull the free end63in a direction that is downwards and leftwards inFIG. 14.

On the inside surface of the tab61is provided a latching edge64, which is best seen inFIGS. 9, 13 and 14. The latching edge64is provided at a junction between a latching face and another face. The latching edge64extends for the width of the tab61. The latching face is in a plane that extends approximately radially with respect to the longitudinal axis of the injection1when the closure68is in the closed position, as shown inFIG. 14. In this position, the latching edge64is engaged with a latch engaging face66that is provided as a part of the uppermost portion of the supplemental device2, i.e. is provided as a portion of the supplemental device2that is not part of the closure68. The latch engaging face66is provided in a plane that is generally the same orientation as the plane of the latching face when the closure68is in the closed position.

When the user has mated the supplemental device2onto the injection pen1, in particular mating the locating rib70within the locating channel71and locating the protuberances53,54within the indents51,52, the user may secure the supplemental device2to the injection pen1. This is achieved by the user moving the closure68from the position shown inFIG. 9, in which the injection device receiving channel58is open for inclusion of the injection pen1therein, and rotating the closure68around the shaft59of the hinge so as to move the free end63of the tab61towards the latch engaging face. Movement continues until contact is made between the innermost part of the latching edge64against a guide surface65, which is located just beneath (as shown in the Figures) the latch engaging face66. The guide surface65is angled approximately tangentially to the outside surface of the housing10of the injection pen1.

At this point, the tendency of the closure68to adopt the shape shown inFIG. 13provides a spring force between the end of the tab61and the guide surface65. As the user exerts further force against the closure68, the closure68deforms resiliently so as to increase the separation between the free end63of the tab61and the hinge59. This allows the edge of the latching edge64to slide over the guide surface65. This continues until the latching edge64becomes aligned with the edge between the guide surface65and the latch engaging face66, at which point the latching edge64and the latching face engage within the channel that is formed against the latch engaging face66. At this point, the resilience of the closure68results in the latching edge64and the latch engaging face66becoming engaged with one another, and at this point the components are in the position shown inFIG. 14. In this position, it will be seen that the innermost surface of the closure68is snug against the outermost surface of the housing10of the injection pen1. At this point, the closure68ensures that the injection pen1is tightly contained within the injection device receiving channel58and is held in place by the closure68.

It will be appreciated that this arrangement prevents movement of the injection device1relative to the supplemental device2in the plane ofFIG. 14.

Movement of the supplemental device2along the longitudinal axis of the injection pen1is inhibited by the mating between the protuberances53,54and the indents51,52. Additionally, movement of the supplemental device2in a rightwards direction as shown inFIG. 8is further prevented by the locating rib70acting against the body20of the supplemental device2.

In some embodiments, the locating rib70and the locating channel71are absent. In these embodiments, the correct alignment between the supplemental device2and the injection pen1is provided by mating of the protuberances53,54and the indents51,52.

In some other embodiments, the right and left arms55,56and the protuberances53,54are absent. In these embodiments, the correct alignment between the supplemental device2and the injection device1is provided by the locating rib70and the locating channel71.

Of course, other alternative arrangements for ensuring a correct relative position between the supplemental device2and the injection pen1will be envisaged by the skilled person, and all such alternatives are within the scope of the invention except when explicitly excluded by the language of the claims.

Also, the skilled person will be aware of alternative securing arrangements, for instance clamping, the supplemental device2to the injection pen1once the correct relative position has been attained. Such alternatives include various other latching mechanisms involving a resilient component, such as a tab or an arm, and no complicated moving parts. Other such embodiments involve more complicated moving parts, for instance clamps with twist-to-lock mechanisms, tension clips and other such mechanisms. A hinge is a relatively simple way of connecting the main body of a supplemental device with a closure part, although alternative connection arrangements will be envisaged by the skilled person. Suitable connection arrangements may include slide mechanisms, clips, etc.

FIG. 15is a cross-sectional view through the supplemental device2and the injection pen in a direction perpendicular to the axis of the injection pen1. The cross-section is through the OCR reader25, which is in the form of a camera. The camera25may also be called a sensor.FIG. 15is not a true cross section in that third and fourth LEDs29d,29c, which are beyond the cross-section, are visible.

InFIG. 15it can be seen that the dosage window13is of even thickness in cross-section and has a shape that forms part of a cylindrical annulus. The axis of the cylinder on which the dosage window13falls is the axis of the injection pen1. The dosage window13may be slightly conical in the axial direction.

InFIG. 15, the supplemental device2is engaged with the injection pen1, forming a snug fit therewith. Moreover, the supplemental device2and the injection pen1are aligned correctly, by virtue of the mating of the protuberances53,54in the indents51,52and the mating of the alignment rib70and the alignment channel71. In this position, the camera25is directed at the dosage window13.

Interposed between the camera25and the dosage window13is a protection window80. The window80is shown inFIG. 16andFIG. 18also. As best seen fromFIG. 15, the protection window80includes a lowermost surface that falls on the curved surface of a cylinder having an axis aligned with the axis of the injection pen1. The uppermost surface of the protection window80has a smaller radius. Thus, the protection window80has a greater thickness at its central part, which is in the path directly between the camera25and the axis of the injection pen1, than it does at its edges. Thus, the protection window80has optical power. The protection window80is configured such that it forms part of the imaging system of the camera25, along with the lens25a. The lens25sin these embodiments has two lenses, referred to as a lens for ease of explanation. The optical power of the protective window80can be seen also in the end view of theFIG. 16aand in the cross-section ofFIG. 16b. The optical power of the protection window80allows a short track length and contributes to a compact arrangement.

The protection window80may be formed of any suitable optically transparent material. For instance, the protection window is formed of optics grade plastics, for instance optics grade polycarbonate or PMMA (polymethyl methachrylate acrylic).

At the left edge of the window81is provided a feature that connects with a left window support83that forms part of the body20of the supplemental device2. A feature82on the right edge of the window is similarly configured to rest against a right window support84that forms part of the body20of the supplemental device2. The left and right window supports83,84serve to support the protection window80in a correct location with respect to other components of the supplemental device2. The protection window80includes features at the left and right ends of the window, as shown inFIG. 16b, that serve to allow mechanical coupling with features of the supplemental device2and which are not relevant to the optical system, so are not described here.

The protection window80is sealed with respect to the body. This prevents the ingress of dirt, dust and other debris into the body20and thus helps to maintain correct operation of the camera25and other parts of the optical system. Thus, the protection window80forms part of the mechanical configuration of the body20of the supplemental device as well as part of the optical system. This helps to allow compactness in the overall arrangement.

As is best seen inFIG. 1a, the dosage window13is not square with respect to the injection pen1. Instead, the dosage window is at an angle, which allows the dosage sleeve19to provide numbers in a helical fashion, the numbers appearing in the dosage window13as the dosage dial12is rotated by a user and a dose is delivered. In the SoloStar injection pen produced by Sanofi, the dosage window13and the markings on the dosage sleeve19are inclined at 13 degrees.

As can be best seen fromFIGS. 17 and 18, the optical arrangement comprising the camera25and the first to fourth LEDs29a-29dare skewed with respect to the main axis of the injection device1. The optical components are skewed to be aligned with the skewed lumber sleeve19and dosage window13. In the case of a SoloStar injection pen, the amount of skew is 13 degrees.

As best seen fromFIG. 17andFIG. 18, the first to fourth LEDs29a-29dare separated from the lens25aof the camera25. In this example, they are distributed around the lens25a. The LEDs29a-29dare configured to illuminate the dosage sleeve19, so that markings on the dosage sleeve can be read by the camera25. As can be seen best fromFIG. 15, the LEDs29a-29dare angled or tilted towards the centre of the dosage window13. This provides more effective illumination of the dosage sleeve19and can improve overall efficiency of the illumination.

The field of view of the camera25covers the whole width of the dosage sleeve19. The field of view of the camera25also covers a sufficient part of the length of the dosage field19that markings provided on the dosage sleeve are captured by the camera25during operation. Illumination from the first to fourth LEDs29a-29dpasses through the protection window80and the dosage window13of the injection pen1to illuminate the dosage sleeve19, on which dose number markings are present. The camera25is arranged to view the dosage sleeve19, taking into account refraction caused by the protection window80and the dosage window13. As mentioned, the protection window80is part of the imaging system of the camera25.

The LEDs29a-29dare arranged so as to achieve substantially uniform illumination of the dosage sleeve. This is achieved by using LEDs29a-29dwith substantially uniform illumination patterns within defined angular and spatial ranges. The LEDs29a-29dare positioned so that, taking into account the optical effects of the protection window80and the dosage window13, a uniform illumination pattern is obtained at the dosage sleeve19.

Each of the first to fourth LEDs29a-29dilluminates a portion of the dosage sleeve19including the whole of the quadrant of the dosage sleeve19that is closest to the respective LED29and including the centre point of the dosage sleeve19, which is directly beneath the camera lens25a. In some embodiments, each of the LEDs29may illuminate only their respective quadrant and extend slightly into neighbouring quadrants. In other embodiments, each of the LEDs29illuminates a greater proportion of the dosage sleeve. For instance, each LED may illuminate more than 60%, more than 70% or more than 80% of the dosage sleeve. The greater the area illuminated by each of the LEDs29, the better is the illumination of the dosage sleeve19.

Each of the LEDs29is positioned relatively distant from the camera lens25in the plane of the camera lens. The LEDs29lie approximately in the plane of the camera lens25a, although as can be seen inFIG. 15in this particular example the LEDs29lie slightly below the plane of the camera lens25a. This contributes to the compactness of the supplemental device2. It also prevents the absorbing of light through other device features such as a barrel of the camera lens25a. Thus, also it contributes to better homogeneity and overall brightness level.

As can be seen fromFIG. 17, the first to fourth LEDs29a-29dare not located directly above the dosage window13. Instead, they are located slightly to the side. This does not affect the optical arrangement because the LEDs29a-29dhave illumination patterns that extend towards the dosage window13.

In other embodiments, the LEDs are not tilted and instead all radiate in a common direction from the plane in which they lie. In further embodiments, a light guide with outcoupling features is used. This can provide a more even illumination.

As can be best seen fromFIG. 18, the protection window80extends between the LEDs29a-29dand the dosage window13. The protection window80covers all or substantially all of the area of the dosage window13.

The LEDs29and the protection window80are arranged such that light paths meet boundaries between air and optical components at angles that are less than the angle of total internal reflection for the boundary. The protection window80is formed of a material that reflects relatively little light that is incident at angles less than the angle of total internal reflection.

For a given one of the LEDs29a-29d, there will be a point on the lowermost surface of the dosage window13at which light could reflect directly onto the camera. For each LED29, there is also a point on the uppermost surface of the dosage window at which light could reflect directly onto the camera25. This reflected light can be termed reflex. Reflexes from the lowermost surface of the dosage window13, which is the surface closest to the dosage sleeve19, are more relevant to correct imaging by the camera25. Reflexes are experienced because the dosage window13is not coated with a non-reflective coating. The dosage window13may be made of relatively low-cost polycarbonate, which usually has relatively reflective surfaces.

On the lowermost surface of the dosage window13, there is a point where light from the fourth LED29dwould reflect to the camera lens25a. This point may be termed the reflection point of the fourth LED29d. At the reflection point of the fourth LED29d, light from the LED29dhas passed through one boundary from air into the material of the protective window80and through another boundary from the material of the protective window80to air. Because the protective window80has an optical power, the direction of incidence of a ray of light on the uppermost surface of the dosage window13is different from the direction of the same ray when it left the fourth LED29d. Light arriving at the uppermost surface of the dosage window13is refracted again by the boundary between air and the dosage window13and continues towards the lowermost surface of the dosage window13. From the reflection point of the fourth LED29d, reflected light would be refracted at three boundaries provided by the uppermost surface of the dosage window13and the two surfaces of the protection window80before arriving at the camera lens25a. As such, and because the protection window80has an optical power and because of refraction provided at the uppermost surface of the dosage window13, the direction of travel of the reflected ray leaving the lowermost surface of the dosage window13is different to the direction of travel of the ray when it is incident on the camera lens25a.

The reflection point for the fourth LED29dis one where a first line perpendicular to the lowermost surface of the dosage window13lies in a first plane in which the light incident from the fourth LED29dand the light reflected to the camera lens25aalso lie, and in which an angle from the first line to a second line that connects the light incident from the fourth LED29dto the reflection point is the same as an angle from the first line to a third line that connects the reflection point to the light passing to the camera lens25a.

There are two main sections to the central window part of the protection window80, which will now be described with reference toFIG. 16d. The main sections will be referred to as a central portion and a periphery portion. The central portion is indicated by Rx and the periphery portion is indicated by Ry. The central portion Rx has a different optical power than the periphery portion. In these embodiments, the surface of the protection window80that is closest to the dosage window in use has a constant radius and the radius of the surface on the side of the protection window80that is closest to the camera25is different for the central portion Rx and the periphery portion Ry. However the converse may be true or there may be different radii on both surfaces. Here, Rx indicates the central portion and also indicates the radius of the surface closest to the sensor25, and Ry indicates the periphery portion and also indicates the radius of the surface closest to the sensor25.

Most or all of the central portion Rx lies on the optical path between the sensor25and the area of interest of the sleeve19that is visible through the dosage window13. The periphery portion Ry does not lie on the optical path between the sensor25and the area of interest of the sleeve19that is visible through the dosage window13. However, some or all of the periphery portion Ry does lie on the optical path between the light sources29and the area of interest of the sleeve19that is visible through the dosage window13. Consequently, the central portion Rx is part of the optical imaging system for reading the numbers visible on the part of the sleeve19that is visible in the dosage window13, and the periphery portion Ry is not part of this optical imaging system. However, the periphery portion Ry is part of the optical system by which illumination of the sleeve19that is visible through the dosage window13by the light sources29is achieved. At least some of the central portion Rx also is part of this optical illumination system.

The central portion Rx forms a convex lens, which has a greater thickness at its centre than it does at its periphery. The periphery portion Ry may have no optical power at all, in that it may not converge or diverge incident light. Thus the central portion Rx and the periphery portion Ry have different optical powers.

The shape of the central portion Rx has an effect of reducing pin cushion distortion, as is described below. This is not true of the periphery portion Ry for two reasons: firstly, it has no optical power and secondly it is not part of the imaging optical path. However, the periphery portion Ry does assist in providing even illumination of the sleeve19by the light sources29. This results because of the location of the periphery portion Ry in the optical illumination path between the light sources29and the sleeve19and because the periphery portion Ry is optically sound.

The provision of the periphery portion Ry with lower optical power than the central portion Rx (e.g. zero optical power compared to negative power) allows the protection window80to be formed with less material than would be possible if the same optical power was applied across the whole width dimension of the protection window. This can reduce the cost and weight of the supplemental device2. Moreover, the thickness of the centre of the protection window80is lower, for a given radius Rx and a given width of protection window80, which can contribute to a more compact arrangement. The thickness of the material at the periphery portion Ry dictates the mechanical strength of the protection window80and is chosen such that the protection window80has a suitable mechanical strength.

In the absence of the central portion Rx of the protection window80as described above, the output of the camera25would experience pin cushion distortion. In the particular arrangement shown, there are two sources for the pin cushion distortion. The first is the optical system of the camera25and its lens25ain conjunction with the dosage window13. Pin cushion distortion results from the optical system in part from the short track length, i.e. the short distance between the camera25and the dosage window13, and in part from the shape of the lens25s. Secondly, pin cushion distortion results also from the curved shape of the sleeve19. The pin cushion distortion that would be experienced in the absence of the central portion Rx of the protection window80is shown inFIG. 19a. This is the output of a camera viewing an even rectangular grid of squares. It will be seen that the grid is not rectangular in the camera output, but is pin cushion shaped.

The output of the same camera in the same situation but with the protection window80in place with the central portion Rx in the imaging optical path is shown inFIG. 19b. Here, it will be seen that the pin cushion distortion is significantly reduced, although still present to some degree.

Removal or reduction of pin cushion distortion is advantageous because it allows better performance by the OCR system25. In particular, performance is better because the numerals/characters on the sleeve19in the dosage window13are more reliably detected by the OCR system25and/or are detected using fewer processing resources. Using fewer processing resources reduces power consumption. More reliable numeral/character detection results in improved operation of the supplemental device2and an improved user experience.

There are two main alternatives for the shape of the optical part of the protection window80.

In a first alternative, the surface of the protection window80that is closest to the sensor25has a cylindrical shape. Because the surface of the protection window80that is closest to the sleeve19is also cylindrical, in this alternative the protection window80has a constant thickness along its length, which is the dimension shown in cross section B-B ofFIG. 16f. This applies particularly to the central portion Rx, but it also applies to the periphery portion Ry. In the first alternative, the central portion Rx forms a cylindrical lens.

In a second alternative, the central part Rx of the protection window80is toric, and forms a toric lens. In this alternative, the protection window80has a thickness that is greatest at a point at or close to the middle part along its length, which is the dimension shown in cross section B-B ofFIG. 16f, and tapers to lower thicknesses at distances further from the point where it has the greatest thickness. Advantageously the surface of the protection window80that is closest to the sleeve19is cylindrical and the surface that is closest to the camera25is curved, but the converse may be true or both surfaces may be curved in the length direction. This applies only to the central portion Rx; the periphery portion Ry does not have a toric lens shape.

A cylindrical lens, according to the first alternative, is simpler to make than a toric lens. The ability to remove pin cushion distortion is similar for a toric lens as for a cylindrical lens.

The transition between the central portion Rx and the periphery portion Ry may be a step transition, or it may be graded over a short distance. A step transition may provide better optical performance, but a graded transition may be simpler to manufacture.

The protection window80is formed of an optical plastic, for instance polycarbonate. This allows the protection window80to be made at low cost whilst allowing the optical imaging system to function correctly (other materials have inferior optical properties and could reduce the effectiveness of the optical imaging system).

However, the use of optical plastic can introduce optical reflexes, which would reduce the effectiveness of the optical imaging system. Optical reflexes result from the refractive index variation from air. This is mitigated in the present embodiments through the application of an anti-reflective coating on the protection window80. The anti-reflective coating may be applied to the surface that is closest to the camera25. It may alternatively be provided to the surface that is closest to the sleeve19. Alternatively, it may be applied to both of these surfaces.

By using an anti-reflective coating consisting of relatively few dielectric single layers, the coating can be made to be very stable under common environmental conditions. Here, the anti-reflective coating may consist of between three and five dielectric single layers. The shape of the reflective spectrum of this type can be described as a V-form spectrum.

Various alternatives will be apparent to the skilled person and all such alternatives are within the scope of the invention unless excluded by the scope of the claims.

For instance, instead of LEDs, any other suitable light sources may be used. Suitable light sources may include light bulbs, laser diodes and organic LEDs.

Although four light sources are included in the shown embodiments, in other embodiments there are one, two, five or more than five light sources. The choice of the number of light sources may depend on the particular light source type chosen, brightness, efficiency and cost requirements.

Also, although the protection window80is located close to the dosage window13when the supplemental device2is in position on the injection pen1in the embodiments above, they may instead be separated by a significant distance. Providing the protection window80close to the dosage window13contributes to providing a compact arrangement. The provision of a compact arrangement is assisted by the provision of the protection window80as described above.