GB2576220A

GB2576220A - Laser marking apparatus

Info

Publication number: GB2576220A
Application number: GB1814042.6A
Authority: GB
Inventors: Blackburn Richard; Grant Ronald Naples Mark
Original assignee: DataLase Ltd
Current assignee: DataLase Ltd
Priority date: 2018-08-09
Filing date: 2018-08-29
Publication date: 2020-02-12
Also published as: GB201814042D0; WO2020030932A1

Abstract

An apparatus for marking a container 2 comprising colour change material operable to change colour in response to controlled exposure to laser light comprises: a platform (3, Fig.2b) for retaining the container; container sensing means 12a-c operable to detect the position or orientation of the container; a marking head (14, Fig.2b) operable to emit laser light so as to mark the container; and a platform actuator (13, Fig.1) operable to move the platform relative to the marking head. A control unit (11, Fig.1) is operable to control the platform actuator and marking head in response to the container sensing means so as to mark a desired image on the container. The platform and marking head may be provided within a chamber (10, Fig.2a), accessed via a door (7, Fig.2a) having extraction means 31-34 operable to generate an airflow so as to remove exhaust material generated during the marking process. The marking head may be a NIR laser or a multi-emitter array. Further provided is a method of marking a container and a container having a panel (21, Fig.8a) of colour change material and an over print layer (23, Fig.8b) for protecting the panel. The container is preferably a cup.

Description

Technical Field of the Invention

The present invention relates to a laser marking apparatus. In particular, the invention relates to a laser marking apparatus suitable for marking a disposable container such as a food or beverage container.

Background to the Invention

At many food or beverage outlets, it is common to serve the food or beverage in a dedicated container. In many instances, the container will be a single use container enabling the user to carry away the food/beverage for consumption away from the point of sale in a hygienic manner. Typically, the container may be branded with the brand of the outlet or with the brand of the supplied food/beverage.

Many food and beverage brand owners are looking for new ways to connect with their customers. One way to do so is with personalisation of disposable food/beverage containers. Such action could provide much desired engagement with customers. Personalised marking of containers may also be desirable in situations where an outlet utilises standard containers for multiple different orders. In such cases, it would be desirable to be able to mark the containers so as to provide an indication of the contents and/or to provide any applicable nutrition or allergen information.

In order to be a viable option, personalisation must be achievable without inconveniencing the customer. It must also be easy to implement for the relevant staff. This therefore requires a relatively compact apparatus, locatable at the point of sale. Furthermore the apparatus has to be adapted to operate relatively quickly so as to avoid delaying the staff and/or customers. Whilst personalisation could be achieved by use of a label printer to print individual labels, which can be applied to the appropriate container by staff, this approach has some key drawbacks. Firstly, it relies upon staff to apply correct labels to the correct container. Secondly, there is the additional onus on staff to maintain and replenish a supply of consumables (labels, ink etc). Thirdly, there may be hygiene or contamination concerns about the use of the consumables in a food/drink preparation area. Finally, many labelling or printing systems can suffer from reliability issues, for instance excessive ink blocking print nozzles, label adhesive clogging label applicator mechanisms and the like.

It is therefore an object of the present invention to provide an apparatus for marking a disposable container that meets the above requirements.

Summary of the Invention

According to a first aspect of the present invention there is provided an apparatus for marking a container comprising colour change material operable to change colour in response to controlled exposure to laser light, the apparatus comprising: a platform for retaining the container; container sensing means operable to detect the presence, position or orientation of the container relative to the platform; a marking head operable to emit laser light so as to mark the container; a platform actuator operable to move the platform relative to the marking head; a control unit operable to control the operation of the actuator and marking head in response to the container sensing means so as to mark a desired image on the container; wherein extraction means are provided, the extraction means operable to generate an airflow from the container to an extraction outlet.

The apparatus thus provides for quick, convenient marking of a container at the point of sale. Furthermore, the marking can be achieved without requiring the stocking or replenishing of consumables. Additionally, the apparatus is adapted to minimise the prospect of contamination of the container, its contents or the surrounding environment as a result of any exhaust material generated during the marking process. In this context, exhaust material may include fumes and/or particulate matter generated as a result of the interaction between the laser light and the colour change material or the bulk material making up the container. Exhaust material may also include fumes and/or particulate matter generated as a result of the interaction between the laser light and contamination acquired during manufacture or subsequent handling of the container. Whilst such exhaust materials are generally non-toxic they can be considered unsightly or off putting to consumers of food or beverages.

The extraction means may comprise an air outlet provided below or around the base of the platform. The extraction means may further comprise an airflow generator positioned so as to generate an airflow into the air outlet. Suitable airflow generators include but are not limited to fans, blowers, “venturi effect” suction devices, and the like. This ensures that any exhaust material generated during the marking process is drawn into the air outlet and away from the container. The extraction means may also comprise a filtration unit. The filtration unit may comprise any one or more of a HEPA filter, an activated carbon filter or the like. HEPA filters may provide for effective particle filtration. Active carbon filters may provide for effective filtration of odorous or noxious volatile substances.

The extraction means may further comprise an air inlet provided above the platform. The air inlet may be connected to a supply of fresh air. The fresh air may be filtered air. This can facilitate the maintenance of a constant air temperature within the chamber, contributing to consistent marking results independent of the frequency and intensity of marking. In some embodiments, the air inlet may be adapted to draw air though a filtration unit. In some embodiments, the air inlet may be connected to a supply of cool air or may be adapted to draw air through a cooling device. In some embodiments, the cool air may be drawn past one or more components of the apparatus. This can facilitate cooling of components such as the marking head or laser.

The air inlet may be positioned such that there is space for the container between the platform and the air inlet. The air inlet can help generate an airflow downward around the side of the container, thus drawing any exhaust material generated during the marking process downward, away from the container. In particular, this may help draw exhaust material away from any open face of the container.

The platform and marking head may be provided within a chamber. The chamber may be defined by a base, sidewall and a roof. In one embodiment, the chamber may be substantially cylindrical. In another embodiment, the chamber may be substantially cuboid.

The chamber may be accessed by a door. The door may be actuated manually or by use of a powered actuator. The door may be provided in the sidewall. In some embodiments, the door may be provided in the roof or may extend from the side wall into the roof. The door may be a hinged door or a sliding door. The dimensions of the door may be selected to enable the container to be readily placed on or removed from the platform within the chamber. In some embodiments, the door may be adapted to allow containers to be placed on or removed from the platform within the chamber by an automated device. In such embodiments, a magazine may be provided in which multiple containers may be stored prior to marking.

The door and chamber may be substantially opaque. In this manner, a user may be protected from exposure to laser light from the marking process when the door is shut. The user and any consumers are also protected from viewing any exhaust material generated during the marking process. In some embodiments, the door or chamber may be provided with a viewing window. The viewing window may be substantially opaque to the laser light used for marking. The viewing window may be substantially transparent to visible light.

The door may be adapted to form a substantially airtight seal with the chamber. This can help generate a desired airflow within the chamber. It may also help minimise potential contamination of the surrounding environment by exhaust products of the marking process.

In some embodiments, a sensor may be provided to sense the position of the door. In such embodiments, operation of the marking head may be inhibited unless the door sensor output indicates that the door is closed. In such embodiments, operation of the extraction means may be initiated in response to the door sensor output indicating that the door is closed.

The door sensor may be a proximity sensor. The door sensor may comprise magnetic sensing elements including Hall effect sensors, photoelectric sensing elements, capacitive sensing elements, inductive sensing elements or the like. In some embodiments, two or more door sensors may be provided. This provides a back up in case one sensor fails. The two or more sensors may be two or more sensors of the same type or may be sensors of different types.

The air outlet maybe provided in the base of the chamber. The air inlet may be provided in the roof of the chamber. A secondary air inlet may be provided in the vicinity of the door. This can enable equalisation of pressure inside and outside the chamber. The secondary air inlet may be provided with shielding or may be otherwise adapted to prevent laser light escaping the chamber.

The platform may be provided with a platform air outlet. The platform air outlet may be connected to the airflow generator. The platform air outlet may be provided on an upper surface of the platform. In this manner, operation of the airflow generator can generate a negative pressure at the platform air outlet which helps to retain the container in position.

The platform may be adapted to retain the container in a desired position. This may be achieved by the provision of stepped or recessed portion of the platform corresponding to the exterior of the container. In such embodiments, the platform may be provided with a series of stepped or recessed portions. This can enable the platform to retain multiple different sizes of container of the same type and/or to retain multiple different types of container. In the case of a cup, the platform may comprise a series of peripheral steps. In such cases, each step may correspond to the radius of a downwardly projecting base rim of a different sized cup.

In some embodiments, the platform may comprise a gripping mechanism. The gripping mechanism may comprise one or more biased arms. In some embodiments, there may be two, three or more arms. The arms may be connected to one or more biasing springs at a base end. The arms may be free to rotate about a pivot spaced apart from the base end. The arms may comprise a contact end, distal from the base end for contacting the container. Through this contact and the urging of the bias, the container may be releasably retained in a desired position. Additionally, the use of the biased and pivoted arms enables adjustment for different sized containers.

In some embodiments, the platform may be replaceable. This can enable the platform to be readily removed for cleaning or repair. Use of different replaceable platforms can enable the apparatus to retain different sizes or types of container.

The apparatus may be operable to mark an image on the container. The image may comprise text, numbers, codes or the like, pictographic elements or a mixture thereof. In some embodiments, the control unit may be operable to select one of a plurality of stored images for marking. In other embodiments, the control unit may be operable to generate an image from one or more stored image elements. The appropriate image or image elements may be selected in response to user actuable input means. Additionally or alternatively, the appropriate image or image elements may be selected in response to signals received from an external device. In further embodiments, the control unit may be operable to receive images or image elements for marking from an external device.

The external device may be connected to the control unit via a suitable wired or wireless communication link. In some embodiments, the external device may be a point of sale terminal. This enables marking to be carried out in response to sales information. In such embodiments, the control unit may automatically select image elements corresponding to ingredient, allergen or nutrition relevant to the food or beverage in the container in response to information received from the POS terminal.

In other embodiments, the external device may be an external server. This can enable controlled marking of serial numbers, vouchers or the like. In other embodiments, the external device may be a user device such as a smartphone or the like or a user identification device such as a card reader or the like. This can enable the marking of images or image elements identifying the user or desired by the user.

In some embodiments, the connected external device may facilitate remote diagnostic and repair services. This can allow rapid response to and resolution of issues arising at the use location.

In some embodiments, the external device may collect and store usage information. This can facilitate invoicing and payment for the equipment or for the use of the equipment on a ‘pay-per-prinf basis.

The container sensing means may comprise one or more optical sensors.

In some embodiments, the container sensing means may comprise one or more beam sensors. Such sensors may be operable to detect the reflection of an emitted beam from an opposing mirror. In such embodiments, failure to detect the emitted beam may imply the presence of a container. In embodiments comprising a plurality of such sensors, the inferred presence of a container by some but not all sensors can be used to determine the size of type of container present.

In some embodiments the container sensing means may comprise one or more cameras. In embodiments comprising one or more cameras, the camera or cameras may be operable to capture an image. The sensor may be provided with a processing unit operable to process the image so as to identify a container and the position of the container. The processing unit may be integrated into the sensor. The processing unit may be integrated into the control unit. The processing unit may additionally be operable to identify the size of the container or the relative orientation of the container. The orientation of the container may be determined by identifying one or more surface features of the container. The surface features may comprise registration marks or other marks, including but not limited to pre-printed graphics such as company logos seasonal images or promotional content.

In some embodiments, the container sensing means may comprise a distance measurement sensor. The distance measurement sensor may be operable to measure the distance to the surface of the container. In the event that the container has a seam or the like, this can be detected as a sharp discontinuity in distance from sensor to container. In this way, the rotational position of the container can be determined.

The platform actuator may be operable to rotate the platform about a substantially vertical axis. In such embodiments, the platform actuator may comprise a motor, for example a stepper motor, a servo motor or the like. The platform actuator may be connected to the platform via a drive shaft. The platform actuator may be operable to rotate the platform such that the container is in a desired orientation.

The apparatus may comprise a marking head actuator operable to move the marking head relative to the platform. This can enable a greater area of the container to be marked. In one embodiment, the marking head actuator is operable to move the marking head in a different direction relative to the container than the platform actuator. In one such example the marking head actuator may be operable to move the marking head in a substantially vertical direction. In such embodiments, the marking head actuator may be mounted on one or more substantially vertical rails or shafts. The marking head actuator may comprise a motor, for example a stepper motor. The marking head actuator may be connected to the marking head via a suitable drive shaft or drive belt.

In some embodiments, the apparatus may include a primary marking head and one or more additional marking heads. Additionally or alternatively, the apparatus may include additional illumination means. The additional marking heads or additional illumination means may be operable to emit light at different wavelength to the primary marking head. Use of additional marking heads emitting different wavelengths and/or use of additional illumination means can enable marking to be carried out in a multistep process. This can provide for full colour marking or for activation of colour change material before marking. Some non-limiting examples of methods for multistep marking are disclosed in our prior international patent applications WO2011/089447 and WO2013/014436.

In some embodiments, the marking head may comprise a single laser emitter. In other embodiments, the marking head may comprise multiple laser emitters.

In embodiments with a single laser emitter, the marking head may comprise light directing means operable to direct light emitted by the single laser emitter onto the container. The light directing means may comprise one or more tilting or rotating mirrors. The or each mirror may be controllably adjusted to scan the emitted light beam across the surface of the container. In one embodiment, the light directing means may comprise a rotating shaft having a plurality of mirrored exterior faces. Rotation of the shaft may enable each mirrored exterior face in turn to scan the emitted light beam across the surface of the container. The shaft may have a regular polygonal exterior profile. In one embodiment, the shaft may have a regular hexagonal profile.

The light directing means may additionally comprise one or more lenses. The lenses may aid in focusing the directed light beam on to the surface of the container. The one or more lenses and/or the focus of the one or more lenses may be controllably adjustable. This can ensure the beam remains focussed across the full range of deflection by the mirrors. It may additionally or alternatively, enable to beam to remain in focus on a non-planar container surface, such as a curved surface.

In some embodiments, the light directing means may additionally comprise a lens assembly operable to focusing the laser beam onto a curved surface of the container, without requiring additional optical mechanisms to adjust focus distance across the full range of deflection.

In some embodiments, the focus of the one or more lenses may be adjusted by use of a controlled optical mechanism provided between the laser emitter and the one or more lenses. The controlled optical mechanism may comprise an adjustable diverging optical element. Motion of the diverging optical element along the optical axis of the mechanism can vary the focal length of the mechanism. This can provide effective control of the focus of the or each lens. Examples of controlled optical mechanisms include but are not limited to the varioSCAN and excelliSHIFT provided by SCANLAB.

The single laser emitter may be provided below the level of the platform. This can provide for more compact arrangement of the apparatus. It may also enable the more delicate components to be readily shielded form spillages or impacts with containers. In such embodiments components of the light directing means may be provided both above and below the level of the platform. In one embodiment, the light directing means may comprise an optical fibre. In another embodiment, the light directing means may comprise one or more tilting mirrors below the level of the platform and a fixed mirror above the level of the platform. In some such embodiments, the fixed mirror may be adapted to reflect the emitted laser light but transmit light in other wave bands. This can enable a camera of the container position sensor to be mounted behind the fixed mirror. It may additionally or alternatively enable a camera for use in observing the marking process to be mounted behind the fixed mirror.

In some embodiments comprising one or more cameras, an image may be captured during the marking process. The image may be processed using the processing means, to assess marking. The assessment may comprise assessment of parameters of the marked image including but not limited to contrast, precision, consistency of marking and the like. In response to the assessment, adjustments may be made to marking system parameters. Adjustable parameters may include but are not limited to laser power, marking speed, laser focus, extraction blower speed and the like. Such adjustments may improve the quality of the remainder of the image marking underway, or to facilitate improvements in the quality of subsequent marked images. Image data and data on the results of the image processing and the resulting changes made to one or more marking system parameters may be stored. Such stored data may be retrieved and reviewed via a local interface or via an external device.

The single laser emitter may be any suitable type of laser. In this context suitable types of laser include but are not limited to CO2 lasers, YAG and other solid state lasers, fibre lasers, diode lasers, fibre-coupled diode lasers, Nd:YVO4 crystal lasers and the like. The single laser emitter may be operable to emit light at any suitable wavelength. This may include wavelengths in the range 400nm to 550nm, 600nm to 700nm, 780nm-2000nm, 900nm to HOOnm, 1060-1080nm, 1400nm to 1600nm or 9200-12000nm. In this context suitable types of laser emit light at wavelengths including but not limited to 450nm, 640nm, 808nm, 830nm, 850nm, 980nm, 1030nm, 1064nm, 1070nm, 1550nm, 10600nm. In one preferred embodiment, the single laser emitter is an NIR laser. In the context of the present invention, the NIR range may include wavelengths from 780nm to 1200nm. Beneficially, this enables the provision of a compact marking head. This is due to the relatively compact nature of NIR lasers as well as the relatively large depth of field provided by use of NIR light. This also enables a relatively small beam diameter to be achieved at the container surface. This in turn enables a relatively large marking area to be marked clearly. As a result, it is possible to faithfully reproduce fine detail in images and text.

In some embodiments, a single laser emitter may be used in conjunction with a spatial light modulator to create a one-dimensional or two-dimensional array profile laser beam. The modulated laser beam may be projected onto the surface of the container. The spatial light modulator may be a multi-channel spatial light modulator Examples of suitable spatial light modulators include but are not limited to Grating Light Valves (GLV), Digital Micromirror Devices (DMD), Liquid Crystal on Silicon (LCOS) or the like.

In some embodiments with multiple laser emitters, the laser emitters may each be mounted in the marking head. In other embodiments, the emitters may comprise the emitting ends of optical fibres, wherein the input ends of said fibres are coupled to one or more laser emitters mounted outside the marking head. The multiple emitters in the marking head may be arranged in an array. The array may be a one-dimensional or two-dimensional array. Where the array is a one-dimensional array, it may be a simple linear array or it may be a staggered array. Provision of the emitters in the head in an array enable the generation of a corresponding array of emitted laser beams for marking.

The multiple laser emitters may be individually addressable. In particular, the individual laser emitter may comprise an individually addressable laser array (IALA) or an individually addressable laser diode array (IALDA).

The multiple laser emitters may be of any suitable type of laser. In this context suitable types of laser include but are not limited to diode lasers, laser diode arrays, fibre-coupled diode lasers. The multiple laser emitters may be operable to emit light at any suitable wavelength. This may include wavelengths in the range 400nm to 550nm, 600nm to 700nm, 780nm-2000nm, 900nm to HOOnm, 1060-1080nm, 1400nm to 1600nm or 9200-12000nm. In this context suitable types of laser emit light at wavelengths including but not limited to 450nm, 640nm, 808nm, 830nm, 850nm, 980nm, 1030nm, 1064nm, 1070nm, 1550nm, 10600nm.

The container may be a disposable or single use container. The container may be adapted for retaining solid food and/or liquid food or beverages. In relation to liquid, the container may comprise a cup, beaker, flask or the like. In some such embodiments, the container may comprise a cap, lid or the like. In one example, a cup may comprise a substantially cylindrical or substantially truncated conical form. In such embodiments, the cup may comprise a downwardly projecting base rim. In relation to solid food, the container may comprise a box, carton, wrapper or the like.

The container may be provided with a panel of colour change material provided over a marking area of the exterior surface of the container. The container may further be provided with an over print layer provided over at least the marking area. The over print layer can reduce scuffing of the colour change material prior to marking. Such scuffing can occur during handling, storage or transit of the container. Scuffing may be particularly likely to occur where the container is stackable. Additionally, suitable over print layer materials may reduce the output of waste fumes during marking operation.

The colour change material may comprise substances including but not limited to any of: a metal oxyanion, a leuco dye, a diacetylene, a charge transfer agent or the like. The metal oxyanion may be a molybdate. In particular, the molybdate may be ammonium octamolybdate (AOM). The colour change material may further comprise an acid generating agent. The acid generating agent may comprise thermal acid generators (TAG) or photo-acid generators (PAG). In one embodiment, the acid generating agent may be an amine salt of an organoboron or an organosilicon complex. In particular, the amine salt of an organoboron or an organosilicon complex may be tributyl ammonium borodisalicylate.

The panel may comprise an NIR (near infrared) absorber material. The NIR absorber material may be operable to facilitate the transfer of energy from an NIR laser illumination means to the colour change material. The NIR absorber material may comprise substances including but not limited to any of: Indium Tin Oxide (ITO), nonstoichiometric reduced ITO, Copper Hydroxy Phosphate (CHP), Tungsten Oxides (WOx), doped WOx, non-stochiometric doped WOx and organic NIR absorbing molecules such as copper pthalocyanines or the like.

The over print layer may be a liquid coating applied over the marking area. The liquid coating may be an aqueous coating or a varnish. Advantageously, aqueous coatings tend to be shinier and smoother than varnish, have higher abrasion and rub resistance, are less likely to yellow and are more environmentally friendly. Many aqueous coatings dry also faster than varnishes. A typical aqueous coating may comprise any one or more of: polymeric resin; wax; silicone; and surfactant. Additional additives may be provided where required or desired.

In some embodiments, the aqueous coating or varnish may be cured after application. Curing may be achieved by any suitable process including but not limited to: exposure to UV radiation; exposure to electron beams or the like. Curing improves gloss and rub resistance and may improve resistance to water or solvents.

The over print layer may comprise a film. The film may be applied using adhesive, solvents or water. Alternatively, the film may be applied using heat. Films may comprise polymers such as polypropylene, polyester, nylon or the like.

In some examples, suitable over print layers may comprise substances including but not limited to: 1541195 INXhrc BB Paper Extender, INXhrc Poly Cup OPV DV51191 or the like.

The apparatus may be adapted to be mounted on or under a shelf or counter. This can beneficially enable the apparatus to be installed adjacent to a point of sale. The apparatus may alternatively be provided in or on a dedicated free-standing cabinet.

According to a second aspect of the present invention there is provided an apparatus for marking a container comprising colour change material operable to change colour in response to controlled exposure to laser light, the apparatus comprising: a platform for retaining the container; container sensing means operable to detect the presence, position or orientation of the container relative to the platform; a marking head operable to emit laser light so as to mark the container; a platform actuator operable to move the platform relative to the marking head; a control unit operable to control the operation of the platform actuator and marking head in response to the container sensing means so as to mark a desired image on the container; wherein the marking head comprises an NIR laser.

The apparatus of the second aspect of the present invention may incorporate any or all features of the first aspect of the present invention as desired or required.

The apparatus thus provides for quick, convenient marking of a container at the point of sale. Furthermore, the use of a marking head comprising an NIR laser enables the provision of a compact marking head. This is due to the relatively compact nature of NIR lasers as well as the relatively large depth of field provided by use of NIR light. This also enables a relatively small beam diameter to be achieved at the container surface. This in turn enables a relatively large marking area to be marked clearly. As a result, it is possible to faithfully reproduce fine detail in images and text.

According to a third aspect of the present invention there is provided an apparatus for marking a container comprising colour change material operable to change colour in response to controlled exposure to laser light, the apparatus comprising: a platform for retaining the container; container sensing means operable to detect the presence, position or orientation of the container relative to the platform; a marking head operable to emit laser light so as to mark the container; a platform actuator operable to move the platform relative to the marking head; a control unit operable to control the operation of the platform actuator and marking head in response to the container sensing means so as to mark a desired image on the container; wherein the marking head comprises a multi-emitter array.

The apparatus of the third aspect of the present invention may incorporate any or all features of the first or second aspects of the present invention as desired or required.

The apparatus thus provides for quick, convenient marking of a container at the point of sale. The use of a multi-emitter array enables high speed marking

According to a fourth aspect of the present invention there is provided a container comprising colour change material operable to change colour in response to controlled exposure to laser light, the container comprising: a panel of colour change material provided over a marking area of the exterior surface of the container; and an over print layer provided over at least the marking area.

The container of the fourth aspect of the present invention may incorporate any or all features of the first, second or third aspects of the present invention as desired or required.

The container thus provides for ready marking of the panel of colour change material. The over print layer can reduce scuffing of the colour change material prior to marking. Such scuffing can occur during handling, storage or transit of the container. Scuffing may be particularly likely to occur where the container is stackable. Additionally, suitable over print layer materials may reduce the output of waste fumes during marking operation.

According to a fifth aspect of the present invention there is provided a method of marking a container comprising colour change material operable to change colour in response to controlled exposure to laser light, the method comprising the steps of: positing a container comprising colour change material operable to change colour in response to controlled exposure to laser light on the platform of an apparatus according to the first, second or third aspects of the present invention; sensing presence, position or orientation of the container relative to the platform; and moving the platform and emitting laser radiation from a marking head in response to the sensed position of the container so as to mark a desired image on the container.

The method of the fifth aspect of the present invention may include any or all features of the first four aspects of the present invention.

Detailed Description of the Invention

In order that the invention may be more clearly understood one or more embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which:

Figure 1	is a schematic block diagram of an embodiment of the container marking system of the present invention;
Figure 2	is a schematic illustration of (a) the exterior of a chamber within which the marking apparatus is housed (b) the interior of said chamber;
Figure 3	is a schematic illustration of the interior of a different embodiment of a chamber within which the marking apparatus is housed;
Figure 4	is a schematic illustration of the (a) operation of the container sensing means in the present invention and (b) one optional aspect of the container sensing means;
Figure 5	is a schematic illustration of (a) a perspective view, (b) a set of comparative cross-sectional views, (c) an enlarged cross-sectional view of one embodiment of a platform for use in the apparatus of the present invention, and (d) an alternative embodiment for the platform;
Figure 6	is (a) a schematic illustration of the operation of the apparatus using a marking head comprising a single laser emitter; (b) a schematic illustration of different marking areas achievable using this embodiment; (c) and (d) possible mirror configurations for use in the apparatus of the present invention; and (e) and (f) an alternative beam deflecting mirror system suitable for use in the apparatus of the present invention.

Figure 7 is (a) a schematic illustration of the operation of the apparatus using a marking head comprising multiple laser emitters, (b) a schematic illustration of a first method for marking an extended marking area, (c) a schematic illustration of a second method for marking an extended marking area, (d) a schematic illustration of a third method for marking an extended marking area; (e) a schematic illustration of one embodiment for marking in a single rotation of the container; (f) and (g) schematic illustrations of an alternate method for employing a multiple laser emitter array for marking; and (h) a configuration of the apparatus using a GLV device with a single laser emitter to produce a complete marked image in a single rotation;

Figure 8 is (a) a schematic illustration of a cup for use in the present invention and (b) a schematic cross-section of the cup along line X-X in figure 8(a);

Figure 9 shows schematic illustrations of alternative containers suitable for use in the present invention; and

Figure 10 shows a focusing lens arrangement suitable for use in the present invention.

Turning now to figure 1, a schematic block diagram of one embodiment of an apparatus 1 for marking a container 2 comprising colour change material operable to change colour in response to controlled exposure to laser light is shown. The apparatus 1 comprises a platform 3 for retaining the container 2. A container sensing means 12 is operable to detect the position or orientation of the container 2 relative to the platform

3. A marking head 14 is operable to emit laser light so as to mark the container 2. A platform actuator 13, typically one or more stepper motors or servo motors, is operable to move the platform relative to the marking head 14. A control unit 11 is operable to control the operation of the platform actuator 13 and marking head 14 in response to the container sensing means 12 so as to mark a desired image on the container 2.

Optionally, the marking head 14 may be provided with a marking head actuator 16, enabling the marking head 14 to be moved relative to the container 2. This can enable the marking head 14 to mark a greater area of the container 2.

In use, the control unit 11 controls the marking head 14 and platform actuator 13 so as to mark an image on the container 2. The image may comprise text, numbers, codes or the like, pictographic elements or a mixture thereof. The control unit 11 can select an image for marking from images stored in a data store 18 or can generate an image for marking from one or more stored image elements from data store 18. Optionally, as is shown in figure 1, the control unit 11 is provided with a communication unit 19. This can enable the control unit to select images or images elements in response to signals from external devices.

Turning now to figure 2, in a typical embodiment the platform 3 and marking head 14 are provided within a chamber 10. The chamber is defined by a base 4, roof 5, and sidewall 6. In the sidewall 6 is provided a door 7, which can be opened to provide access to the interior of the chamber 10. Optionally, the door is provided with a handle

8. The position of the door 7 can be monitored by an optional door sensor 17 (figure 3). Closing the door 7 can beneficially shield users or other bystanders from laser light used in the marking operation. Additionally, it can contain and hide from view any exhaust materials generated during the marking process.

In the example of figure 2, the chamber 10 is provided on a shelf or counter 10a. The skilled man will of course appreciate that the chamber can be provided under such a shelf or counter 10a or in a free standing cabinet, as required or desired.

Within the chamber 10, the container 2 (in the present example a cup) is retained on a platform 3. The position and orientation of the container 2 with respect to the platform 3 is sensed using optical position sensors 12 as will be explained further below. Also shown in figure 2 is a mirror 43 comprising part of the marking head 14 and an extraction air outlet 31 which forms part of an extraction means. The extraction means are operable to generate an airflow using a fan, blower or the like so as to remove exhaust material generated during the marking process and thus prevent contamination or the appearance of contamination of the container 2 or its contents.

Turning to figure 3, an alternative embodiment of the chamber 10 comprises a door 7 extending into the roof 5 as well as sidewall 6. This enables a clearer view of the extraction means 15, in particular extraction outlet 31 and extraction inlet 32. The outlet 31 is connected via a duct 33 to an airflow generator such as a fan (not shown) and ultimately to an external outlet (not shown). A filtration unit (not shown) can optionally be provided prior to the external outlet. This can enable filtration of the airflow for particulate matter and/or odour.

The inlet 32 is connected via a duct 34 to an air supply, which may be the ambient air in the vicinity of the chamber. The duct 34 may be provided with an airflow generator such as a fan (not shown) and or a filter (not shown). The extraction means thereby generates a flow 35 of air via duct 34 through inlet 32, downwardly through the chamber 10 to outlet 31 and thence through duct 33 to the external outlet. In this way exhaust materials generated during marking are removed from the chamber 10 along with the airflow.

Figure 3 further indicates the possibility of using the apparatus 1 to mark different sized containers 2. This is illustrated further in figure 4. In this example, three separate optical beam sensors 12a, 12b, 12c are used to determine that a container 2 is on platform 3 and the size of the container 2 (from three different standard sizes 2a, 2b, 2c).

The beam sensors 12a, 12b, 12c are operable to detect the reflection of an emitted light beam. In the absence of a container 2, the emitted beams will each be reflected by a mirror 12d provided at the opposing side of the chamber 10. Detection of reflections of all three emitted beams indicates that no container 2 is on platform 3. Detection of reflections of emitted beams from sensor 12b and 12c only indicates that a container of the smallest size 2a is present. Detection of reflection of an emitted beam from 12c only indicates that a container of the medium size 2b is present. Detection of reflections of emitted beams from none of the sensors 12a, 12b, 12c indicates that a container of the largest size 2c is present.

To detect the orientation of the container 2, the container sensor may comprise a camera operable to capture an image of the container 2. The image can be processed to determine the orientation of the container by determining the position of distinguishing features of the container such as seams, comers or pre-printed marks. In the example shown in figures 2-4, there is such a camera 12e positioned behind mirror 43. In such embodiments, the mirror 43 may transmit light of a waveband suitable for capture by the camera 12e but reflect light emitted by the marking head 14.

In other embodiments, the container 2 orientation can be determined by use of a reference mark 2d. In such embodiments, the beam sensor 12a is operable both to detect a reflected emitted beam from mirror 12d and from a coded registration mark 2d. In use, the control unit 11 causes the platform actuator 13 to rotate platform 3 until the registration mark 2d is detected by beam sensor 12a. Detection of the registration mark 2d aligned with the beam confirms the alignment of the container. In some cases, the registration mark, as distinguished by features such as shape, pattern, colour or position, may also identify the size and type of container 2. This can allow container position and orientation to be established without use of the additional beam sensors 12b, 12c and camera 12e.

In other embodiments, orientation can be determined by use of a precise distance sensor (not shown). As the container is rotated, the sensor measures the distance from the sensor to the surface of the container 2. At a seam in the wall of the container 2, the sensor will detect a discontinuity in distance, thereby identifying the rotational position of the container. Such a distance sensor can also detect the presence or absence of a container 2, and/or identify the size of container 2 based on the diameter.

Turning to figure 5, an example of the platform 3 is shown. In the example, the platform is optimised for retaining a container in the form of a cup 2. Nevertheless, the skilled man will appreciate that other types of containers 2 could be placed on such a platform 3. Additionally, the skilled man will appreciate that additional platform elements (not shown) may be placed on the platform 3, if required, in order to adequate retain other types of container 2.

In the specific example of figure 5, the platform 3 is provided with a series of peripheral steps 3a, 3b, 3c. As is shown most clearly in figure 5b, in such cases, each step 3a, 3b, 3c correspond to the radius of a downwardly projecting base rim of a different sized cup 2a, 2b, 2c.

Optionally, platform 3 can be provided with an air outlet 3d on its upper surface. The air outlet may connect via a duct 3e to the air flow generator of the extraction means

15. Optionally, a second side duct 3f can additionally be provided. In use, the airflow generator can create a negative pressure within ducts 3e, 3f thereby helping retain the container 2 in position on the platform 3.

An alternative platform configuration is shown in figure 5d. In this embodiment the container 2 is placed onto the platform 3. The platform 3 is provided with a gripping mechanism comprising a set of arms 66 spaced around the circumference of the platform 3. In a preferred embodiment three such arms 66 are provided at 120 degree intervals. The arms 66 are individually pivoted on individual pivots 68. The arms 66 are spring biased to one another using one or more springs 69. In this manner the force applied at a contact end 65 of each arm 66 is balanced across all the provided arms 66. An individual stop 67 is provided for each lever arm 66 to prevent excessive rotation of each lever arm 66 when the container 2 is not present. The contact end 65 of each arm 66 is formed in a smooth curved shape to facilitate smooth insertion and removal of the container 2. The position of the stop 67 is arranged such that the lever arms 66 form a slight interference fit to the tapered base of the container 2 as it is placed onto the platform 3. As the container 2 is pressed down, the lever arms 66 rotate inwards under pressure from spring 69, then rotate outwards to hold the container 2 in position without damage to the container 2. By balancing the forces using a set of springs 69, the container 2 will be self-centring onto the platform 3.

Turning now to figure 6a, the operation of one embodiment of the marking head 14 is illustrated schematically. The marking head 14 comprises a single laser emitter 41. In a preferred embodiment, the laser emitter 41 is an NIR laser but the skilled man will appreciate that other types of laser emitting at other wavelength bands may be used in alternative implementations.

A light beam 46 is emitted by laser 41. In some embodiments the light beam 46 passes through an optional Beam Expander 45 creating an output beam 40 of larger diameter then the input beam 46. In other embodiments the light beam 40 may be emitted directly from the laser 41 at the required diameter, thereby not requiring the addition of the Beam Expander 45. Laser Beam 40 is incident on optional mirror 42 and subsequently on further mirrors 47 and 43 before reaching the container 2. By controlling the tilt of mirror 47, the beam 40 can be focused using focusing lens 44 on a point within a marking area 20 of the surface of the container 2. Modulation of the laser energy received at each point within the marking area 20, by modulation of the beam power, pulse duration, duty cycle, or the like can thereby be used to mark an image on the container 2. In some embodiments, the tilting mirror 47 is operable to tilt in two dimensions so as to control beam incidence position on the marking areas 20 in two dimensions. In other embodiments, as is illustrated in figures 6c and 6d a pair of mirrors 48a and 48b are orthogonally disposed, each mirror operable using independent galvanometer motors 48c and 48d to tilt in one dimension, thereby creating a two dimensional net beam deflection. In other embodiments, the tilting mirror 47 is operable to tilt in a single dimension so as to control beam incidence position on the marking areas 20 in the vertical dimension only.

In a further embodiment shown in figure 6d, the beam expander 45 is replaced with a focus adjustment device 410, which is capable of controlled adjustment of the collimation of output beam 40, thereby adjusting the effective focal plane of the lens 44. In this manner the focus can be adjusted continually during marking to accommodate the curved surface of the container, to accommodate the container-tocontainer variation due to container designs or container tolerances, and to accommodate any variation due to operator placement of the container into the housing. The functionality provided by element 410 may be provided by alternate means, such as the Scanlab intelliSHIFT module.

In yet further embodiments, illustrated in Figure 6e, a spinning polygonal mirror 49 operates to deflect the beam 40 through the lens 44 and via the mirror 43 to the container 2. By controlling the rotational speed of the polygonal mirror 49 in coordination with the modulation of the laser 41, a pattern of laser markings in a vertical plane 401 is created. Figure 6f shows a series of incremental rotational positions (i), (ii) and (iii) of the polygonal mirror 49, with the consequent deflection of beam 40 to the container 2. In any of the above embodiments, control of horizontal position may be achieved by rotation of the container 2 using the platform actuator 13.

As can be seen in figure 6a, the maximum extent of the marking area 20 is sufficient to mark the largest accepted container 2c. In some examples, such as illustrated in figure 6b, the maximum extent of the marking area 20 is also sufficient to mark a medium size accepted container 2b. For a smaller container 2a, the operation of the marking head may be limited to mark a restricted marking areas 20a only. This can be achieved by limiting the range of motion of mirror 42 or mirrors 48a and 48b, and/or by cutting power to the beam 40 when outside the limited marking area 20a.

Turning now to figure 7, the operation of alternative embodiment of the marking head 14 is illustrated schematically. The marking head 14 comprises an array 51 of laser emitters. Typically, this would be a one-dimensional array aligned vertically or substantially vertically, nevertheless other array configurations are possible within the knowledge of the skilled man.

In a preferred embodiment, the array of laser emitters 51 are mounted directly in the head 14. The skilled man will appreciate that the laser emitters may be provided away from the head 14, with light being directed to the head by coupled optical fibres. Typically, the laser emitter are laser diodes of the type Fibre-coupled laser diodes operating at 980nm. The skilled man will however will appreciate that other types of laser emitting at other wavelength bands may be used in alternative implementations

In operation, the head 14 emits a series of parallel laser beams, each of which passes through a permanently attached micro-lens, outputting an array of individually focused laser beams 50 which are directly incident upon the marking area 20 of the container 2. During operation, the container 2 is rotated past the parallel beams 50 using the platform actuator 13. Modulation of the laser energy received at each point within the marking area 20, by modulation of the beam power, pulse duration, duty cycle, or the like can thereby be used to mark an image on the container 2. If the marking head 14 is sufficiently large, then marking of the image can be completed in single rotation. If, as is shown in figures 7a the marking head 14 does not cover the full vertical extent of the marking area 20, marking requires the head 14 to be moved vertically using a marking head actuator 16. The marking area 20 can then be marked in a series of parallel stripes.

In the embodiments shown, the marking head actuator 16 comprises a stepper motor or servo motor 61. The marking head 14 is fixed to a bar 62 and is free to slide along vertical shafts 63. A drive belt 64 is also connected to the marking head 14, driven by motor 61. This enables the vertical position of the head 14 relative to the container 2 to be varied.

In other embodiments as shown in figure 7f and 7g, a marking head 14 may be traversed 402 using any suitable mechanism (including but not limited to a mechanism similar to that shown in figure 7a) so that the linear array of laser beams 50 is projected so as to deflect off mirror 43 and thereby be caused to impinge upon a portion of the marking surface 20 of the container 2. In this context figure 7g illustrates the marking head 14 being traversed 402 from one end position (i) to an intermediate position (ii) to another end position (iii) to enable the array of beams 50 to scan across the full marking area.

Coverage of the full marking area 20 can be achieved using the platform actuator 13 and marking head actuator 16 in any suitable series of motions. Three practical series of movements are shown in figures 7b, 7c and 7d.

In figure 7b, the platform actuator 13 is operated to perform a rotation 53a of the container 2 in a first direction whilst the marking head 14 is active. Subsequently, marking head actuator 16 moves the marking head vertically 54a whilst the marking head 14 is inactive before the platform actuator 13 performs a reverse rotation 53b in a second direction, opposite to the first direction whilst the marking head 14 is active. Marking head actuator 16 then moves the marking head vertically 54b whilst the marking head 14 is inactive before the platform actuator 13 performs a rotation 53c in the first direction whilst the marking head 14 is active. Finally, marking head actuator 16 then moves the marking head vertically 54c whilst the marking head 14 is inactive before the platform actuator 13 performs a rotation 53d in the second direction whilst the marking head 14 is active. Similar steps can be repeated for a larger marking area 20 if required. Equally some steps may be omitted for a smaller marking area 20 if required.

In figure 7c, the platform actuator 13 is operated to perform a rotation 55a of the container 2 in a first direction whilst the marking head 14 is active. Subsequently, the platform actuator 13 and marking head actuator 16 are operated together 56a whilst the marking head 14 is inactive until the marking head 14 is once more positioned adjacent to the marking area 20. Subsequently, the platform actuator 13 is operated to perform a rotation 55b, 55c, 55d of the container 2 in a first direction whilst the marking head 14 is active and the platform actuator 13 and marking head actuator 16 are operated together 56b, 56c whilst the marking head 14 is inactive as necessary to cover the full marking area 20.

In figure 7d, the platform actuator 13 is operated to perform a rotation 58 of the container 2 in a first direction whilst the marking head 14 is active. Concurrently the marking head actuator 16 is operated together with the platform actuator 13 to continually mark the full marking area 20. At the conclusion of marking the marking head actuator 16 is operated to return the marking head 14 to its initial position.

In figure 7e, an alternate embodiment is shown, in which a large marking head 14 outputs a linear array of focused laser beams 50. The linear array of beams deflects off fixed mirror 43 and onto the marking surface 20 of the container 2. In some embodiments, the marking head 14 may be large enough to facilitate marking the complete required container surface area in a single rotation.

In figure 7h, an alternative embodiment is shown, in which a laser 41 emits a laser beam 46. The laser beam 46 passes through a beam shaping optical assembly 403 to produce a flat-top rectangular homogenized laser beam 404. The beam 404 is caused to impinge on a Grating Light Valve (GLV) device 405, which produces an individually modulated linear array of focused laser beams 50. The array of focused laser beams 50 is deflected by the fixed mirror 43 onto the surface of the container 2. The container 2 is caused to rotate on the platform 3 by the platform actuator 13. By coordinating the modulation of the individual elements of the array of focused laser beams 50 with the rotational movement of the container 2, an image can be produced on the container 2 in a single rotation. Commercially available GLV devices (such as the Silicon Light Machines Fl088 and G1088 families) have sufficient individually-addressable pixels to allow a high quality grayscale image to be created in a single rotation of the container

2. Alternative two-dimensional Spatial Light Modulator devices such as DMD and LCOS can be utilized in a similar manner as the GLV 405, creating an array of individually modulated laser beams that is deflected by the fixed mirror 43 onto the surface of the container 2. By coordinating the modulation of the individual elements of the beams with the motion of the container 2, an image can similarly be produced on the container 2 in a single or multiple rotations.

In use, the container 2 may be formed with a panel of colour change material corresponding to the desired marking area. An example of a cup 2 provided with such a panel 21 is shown in figure 8a. The advantage of such a container over one provided with colour change material over substantially the whole surface is that it is cheaper to produce. Indeed, such a container may be pre-printed with standard branding or marketing information. This can enable the container to be used with or without personalised marking as desired.

Turning now to figure 8b, a cross-section X-X through the wall of container 2 illustrates that the colour change material 21 is applied over the bulk material forming the container 22. Subsequently, an over print layer 23 is provided over at least the panel 21 and optionally over the full surface of the container 2.

The over print layer 23 has the benefit of protecting the panel 21 from scuffing. This can be a significant problem in the storage and transit of containers 2 prior to use. As a particular example, panels 21 on a cup 2 as shown in figure 8 might otherwise be at risk of significant scuffing if the cups 2 are stored in a stacked configuration. The over print layer can also help minimise exhaust material generated during marking operation.

The thickness of the over print layer and the over print material selected may be varied depending upon the anticipated scuffing hazard and the additional cost imposed by provision of the layer. Typically, the over print layer is an aqueous coating, which may be cured if necessary. In this context, suitable over print layers for use with containers according to the present invention include 1541195 INXhrc BB Paper Extender or INXhrc Poly Cup OPV DV51191.

The particular colour change material used for the panel 21 will depend upon the nature of the marking head 14, in particular the wavelength of the emitted laser light as is known to the skilled man. In one example, a panel 21 comprising colour change material such as AOM (Ammonium Octamolybdate) can be combined with a NIR absorber such as CHP (Copper Hydroxy Phosphate), together with other materials known to the skilled man forming a printable coating ink, used in combination with a marking head 14 comprising a YAG laser source with three-axis galvanometer marking head.

A typical colour change material may consist of the following:

Liquid Polymeric vehicle	Elvacite 2043 in Ethanol 3:1 Ethyl Acetate	25 to 75 %
Laser Wavelength Absorber	Copper Hydroxide Phosphate	0.01 to 25%
Colour Change Material	Ammonium Octamolybdate	0.5 to 50%
Additives	Surfynol 61	0.01 to 10%

The skilled man will appreciate that the present invention is not limited to marking containers 2 in the form of cups alone. A non-exhaustive series of exemplary embodiments of alternative forms of container 2 are illustrated in figure 9, In the illustrated alternative embodiments, the container 2 may be a sandwich bag 201, a clam shell carton 202, a bulk carryout bag 203, a French fry container 204, a lock-top container 205, a sandwich wrapper 206, a pizza box 207, a soft drink bottle 208, or similar food or beverage packaging containers In these embodiments, possible examples of the position of the panel 21 in each instance are shown. Where the panel is provided on the reverse of a surface visible in figure 9, it is depicted in dotted lines. The skilled man will appreciate that panels 21 can be provided in alternative positions if required or desired.

Figure 10 shows an embodiment in which the laser beam 40 is deflected via mirrors 48a and 48b through a pair of lenses 406 and 407, to provide a focused laser beam 408 impinging on the marking area 20. The distance between the lens 407 and optimum focus point 409 varies across the marking area 20, such that the laser is optimally focused onto the curved surface 20 of the container 2. The variable focus is achieved via the design of cylindrical lens 406 and spherical lens 407. This preferred embodiment does not require a separate mechanism 410 to adjust the focus of the laser beam to maintain optimum focus and optimum marking quality, contrast and speed. In τι yet further preferred embodiments, lenses 406 and 407 may be combined into a single optical element.

The above embodiments are described by way of example only. Many variations are possible without departing from the scope of the invention as defined in 5 the appended claims.

Claims

1. An apparatus for marking a container comprising colour change material operable to change colour in response to controlled exposure to laser light, the apparatus comprising: a platform for retaining the container; container sensing means operable to detect the presence, position or orientation of the container relative to the platform; a marking head operable to emit laser light so as to mark the container; a platform actuator operable to move the platform relative to the marking head; a control unit operable to control the operation of the actuator and marking head in response to the container sensing means so as to mark a desired image on the container; wherein extraction means are provided, the extraction means operable to generate an airflow from the container to an extraction outlet.

2. An apparatus for marking a container as claimed in claim 1 wherein the extraction means comprise an air outlet provided below or around the base of the platform and an airflow generator positioned so as to generate an airflow into the air outlet.

3. An apparatus for marking a container as claimed in claim 1 or claim 2 wherein the extraction means comprise an air inlet provided above the platform.

4. An apparatus for marking a container as claimed in any preceding claim wherein the platform and marking head may be provided within a chamber defined by a base, sidewall and a roof.

5. An apparatus for marking a container as claimed in claim 4 wherein the chamber is accessed by a door.

6. An apparatus for marking a container as claimed in claim 5 wherein the door and chamber are substantially opaque.

7. An apparatus for marking a container as claimed in claim 5 or claim 6 wherein the door is adapted to form a substantially airtight seal with the chamber.

8. An apparatus for marking a container as claimed in any one of claims 5 to 7 wherein a sensor is provided to sense the position of the door.

9. An apparatus for marking a container as claimed in any one of claims 2 to 8 wherein the platform is provided with a platform air outlet connected to the airflow generator.

10. An apparatus for marking a container as claimed in any preceding claim wherein the platform is adapted to retain the container in a desired position by the provision of stepped or recessed portion of the platform corresponding to the exterior of the container.

11. An apparatus for marking a container as claimed in any preceding claim wherein the platform is replaceable.

12. An apparatus for marking a container as claimed in any preceding claim wherein the apparatus is operable to mark an image on the container comprising text, numbers, codes, pictographic elements or a mixture thereof.

13. An apparatus for marking a container as claimed in claim 12 wherein the control unit is operable to select one of a plurality of stored images for marking or is operable to generate an image from one or more stored image elements.

14. An apparatus for marking a container as claimed in claim 13 wherein the appropriate image or image elements is selected in response to signals received from an external device.

15. An apparatus for marking a container as claimed in claim 13 or claim 14 wherein the control unit is operable to receive images or image elements for marking from an external device.

16. An apparatus for marking a container as claimed in any preceding claim wherein the container sensing means comprises one or more beam sensors.

17. An apparatus for marking a container as claimed in any preceding claim wherein the container sensing means comprises one or more cameras.

18. An apparatus for marking a container as claimed in any preceding claim wherein the container sensing means comprises a distance measurement sensor operable to measure the distance to the container.

19. An apparatus for marking a container as claimed in any preceding claim wherein the platform actuator comprises a stepper motor or servo motor.

20. An apparatus for marking a container as claimed in any preceding claim wherein the apparatus comprises a marking head actuator operable to move the marking head relative to the platform.

21. An apparatus for marking a container as claimed in any preceding claim wherein the apparatus comprises a primary marking head and one or more additional marking heads or additional illumination means operable to emit light at different wavelength to the primary marking head.

22. An apparatus for marking a container as claimed in any preceding claim wherein the marking head comprises a single laser emitter.

23. An apparatus for marking a container as claimed in claim 22 wherein the marking head comprises light directing means operable to direct light emitted by the single laser emitter onto the container.

24. An apparatus for marking a container as claimed in claim 23 wherein the light directing means comprise one or more tilting or rotating mirrors.

25. An apparatus for marking a container as claimed in claim 24 wherein the light directing means comprises a rotating shaft having a plurality of mirrored exterior faces.

26. An apparatus for marking a container as claimed in any one of claims 22 to 25 wherein the single laser emitter is provided below the level of the platform.

27. An apparatus for marking a container as claimed in any one of claims 22 to 26 wherein the single laser emitter may be CO2 lasers, YAG and other solid state lasers, fibre lasers, diode lasers, fibre-coupled diode lasers, orNd:YVO4 crystal lasers.

28. An apparatus for marking a container as claimed in any one of claims 22 to 27 wherein the single laser emitter may be operable to emit light at wavelengths in the range 400nm to 550nm, 600nm to 700nm, 780nm-2000nm, 900nm to HOOnm, 1060-1080nm, 1400nm to 1600nm, or 9200-12000nm or at wavelengths of 450nm, 640nm, 808nm, 830nm, 850nm, 980nm, 1030nm, 1064nm, 1070nm, 1550nm, or 10600nm.

29. An apparatus for marking a container as claimed in any one of claims 22 to 28 wherein a spatial light modulator is provided, the spatial light modulator operable to create a one-dimensional or two-dimensional array profile laser beam.

30. An apparatus for marking a container as claimed in any one of claims 1 to 21 wherein the marking head comprises multiple laser emitters

31. An apparatus for marking a container as claimed in claim 30 wherein the laser emitters are each mounted in the marking head.

32. An apparatus for marking a container as claimed in claim 30 wherein the emitters comprise the emitting ends of optical fibres, wherein the input ends of said fibres are coupled to one or more laser emitters mounted outside the marking head.

33. An apparatus for marking a container as claimed in any one of claims 30 to 32 wherein the marking head is a one-dimensional or two-dimensional array.

34. An apparatus for marking a container as claimed in any one of claims 30 to 33 wherein the multiple laser emitters are diode lasers, laser diode arrays, fibrecoupled diode lasers, individually addressable laser arrays (IALA) or individually addressable laser diode arrays (IALDA).

35. An apparatus for marking a container as claimed in any one of claims 30 to 34 wherein the multiple laser emitters are operable to emit wavelengths in the range 400nm to 550nm, 600nm to 700nm, 780nm-2000nm, 900nm to 1 lOOnm, 10601080nm, 1400nm to 1600nm, 9200-12000nm or at wavelengths of 450nm, 640nm, 808nm, 830nm, 850nm, 980nm, 1030nm, 1064nm, 1070nm, 1550nm, or 10600nm

36. An apparatus for marking a container as claimed in any preceding claim wherein the container comprises a cup, beaker, flask, dish, box, carton, bag or wrapper.

37. An apparatus for marking a container as claimed in claim 36 wherein the container comprises a panel of colour change material provided over a marking area of the exterior surface of the container.

38. An apparatus for marking a container as claimed in claim 36 or 37 wherein the container comprises an over print layer provided over at least the marking area.

39. An apparatus for marking a container as claimed in claim 38 wherein the over print layer is an aqueous coating or a varnish.

40. An apparatus for marking a container as claimed in any preceding claim wherein the colour change material comprise: a metal oxyanion, a leuco dye, a diacetylene, a charge transfer agent or the like.

41. An apparatus for marking a container as claimed in claim 41 wherein the colour change material further comprises an acid generating agent.

42. An apparatus for marking a container as claimed in any preceding claim wherein the panel comprises an NIR (near infrared) absorber material.

43. An apparatus for marking a container as claimed in claim 42 wherein the NIR absorber material comprises: Indium Tin Oxide (ITO), non-stoichiometric reduced ITO, Copper Hydroxy Phosphate (CHP), Tungsten Oxides (WOx), doped WOx, non-stochiometric doped WOx or copper pthalocyanines.

44. An apparatus for marking a container comprising colour change material operable to change colour in response to controlled exposure to laser light, the apparatus comprising: a platform for retaining the container; container sensing means operable to detect the presence, position or orientation of the container relative to the platform; a marking head operable to emit laser light so as to mark the container; a platform actuator operable to move the platform relative to the marking head; a control unit operable to control the operation of the platform actuator and marking head in response to the container sensing means so as to mark a desired image on the container; wherein the marking head comprises an NIR laser.

45. An apparatus for marking a container as claimed in claim 44 wherein the marking head comprises a single laser emitter.

46. An apparatus for marking a container as claimed in claim 45 wherein the marking head comprises light directing means operable to direct light emitted by the single laser emitter onto the container.

47. An apparatus for marking a container as claimed in claim 46 wherein the light directing means comprise one or more tilting mirrors.

48. An apparatus for marking a container as claimed in claim 47 wherein the tilt of the or each mirror is controllably adjusted to scan the emitted light beam across the surface of the container.

49. An apparatus for marking a container as claimed in any one of claims 45 to 48 wherein the single laser emitter is provided below the level of the platform.

50. An apparatus for marking a container as claimed in claim 44 wherein the marking head comprises multiple laser emitters

51. An apparatus for marking a container as claimed in claim 50 wherein the laser emitters are each mounted in the marking head.

52. An apparatus for marking a container as claimed in claim 50 wherein the emitters comprise the emitting ends of optical fibres, wherein the input ends of said fibres are coupled to one or more laser emitters mounted outside the marking head.

53. An apparatus for marking a container as claimed in any one of claims 50 to 52 wherein the marking head is a one-dimensional or two-dimensional array.

54. An apparatus for marking a container comprising colour change material operable to change colour in response to controlled exposure to laser light, the apparatus comprising: a platform for retaining the container; container sensing means operable to detect the presence, position or orientation of the container relative to the platform; a marking head operable to emit laser light so as to mark the container; a platform actuator operable to move the platform relative to the marking head; a control unit operable to control the operation of the platform actuator and marking head in response to the container sensing means so as to mark a desired image on the container; wherein the marking head comprises a multi-emitter array.

55. An apparatus for marking a container as claimed in claim 54 wherein the laser emitters are each mounted in the marking head.

56. An apparatus for marking a container as claimed in claim 54 wherein the emitters comprise the emitting ends of optical fibres, wherein the input ends of said fibres are coupled to one or more laser emitters mounted outside the marking head.

57. An apparatus for marking a container as claimed in any one of claims 54 to 56 wherein the marking head is a one-dimensional or two-dimensional array.

58. An apparatus for marking a container as claimed in any one of claims 54 to 57 wherein the multiple laser emitters are diode lasers, laser diode arrays, fibrecoupled diode lasers, individually addressable laser arrays (IALA) or individually addressable laser diode arrays (IALDA).

59. An apparatus for marking a container as claimed in any one of claims 54 to 58 wherein the multiple laser emitters are operable to emit wavelengths in the range 400nm to 550nm, 600nm to 700nm, 780nm-2000nm, 900nm to 1 lOOnm, 10601080nm, 1400nm to 1600nm, or 9200-12000nm or at wavelengths of 450nm, 640nm, 808nm, 830nm, 850nm, 980nm, 1030nm, 1064nm, 1070nm, 1550nm, or 10600nm

60. A container comprising colour change material operable to change colour in response to controlled exposure to laser light, the container comprising: a panel of colour change material provided over a marking area of the exterior surface of the container; and an over print layer provided over at least the marking area.

61. An apparatus for marking a container as claimed in claim 60 wherein the over print layer is an aqueous coating or a varnish.

62. An apparatus for marking a container as claimed in claim 60 or 61 wherein the colour change material comprise: a metal oxyanion, a leuco dye, a diacetylene, a charge transfer agent or the like.

63. An apparatus for marking a container as claimed in claim 62 wherein the colour change material further comprises an acid generating agent.

64. An apparatus for marking a container as claimed in any one of claims 60 to 63 wherein the panel comprises an NIR (near infrared) absorber material.

65. An apparatus for marking a container as claimed in claim 64 wherein the NIR absorber material comprises: Indium Tin Oxide (ITO), non-stoichiometric reduced ITO, Copper Hydroxy Phosphate (CHP), Tungsten Oxides (WOx), doped WOx, non-stochiometric doped WOx or copper pthalocyanines.

66. A method of marking a container comprising colour change material operable to change colour in response to controlled exposure to laser light, the method comprising the steps of: positing a container comprising colour change material operable to change colour in response to controlled exposure to laser light on the platform of an apparatus according to any one of claims 1 to 59; sensing the presence, position or orientation of the container relative to the platform; and moving the platform and emitting laser radiation from a marking head in response to the sensed position of the container so as to mark a desired image on the container.

67. A method as claimed in claim 66 wherein the container is a container according to any one of claims 60 to 65.