WO2000020128A1

WO2000020128A1 - Printing method and apparatus

Info

Publication number: WO2000020128A1
Application number: PCT/GB1999/003240
Authority: WO
Inventors: Peter Herring; Stephen Halewood; Phillip King; Suriaprakash Natotamo
Original assignee: 4Cyte Ltd.
Priority date: 1998-10-01
Filing date: 1999-09-30
Publication date: 2000-04-13
Also published as: GB9821417D0; AU6108099A; GB2342071A

Abstract

A method and apparatus for printing an image on a three-dimensional object (50) is provided, in which the image to be printed is first applied in an on-line process to a water-soluble PVA film (83) mounted in a frame (84). The image is applied to the film by an ink-jet printer. At a printing station (80), comprising a tank (81) of water (82), the film (83) is floated ink uppermost on the surface of the water such that the film begins to dissolve. The object is then lowered into the tank (81), through the ink layer (85) and the dissolving PVA film (83). The water pressure forces the ink into contact with the surfaces of the object (50), thereby applying the image to the object. The image can be specifically configured in relation to the object to be printed and might, for example, contain relief- or contour-related features, names, trade marks or logos, which will require accurate positioning on the object. The image may be dependent on at least some of the contours of the object, and may be adjusted to compensate for image stretch or distortion which would otherwise occur. The apparatus may also be provided with a cleaning station, a drying station, a lacquering station and a curing station.

Description

PRINTING METHOD AND APPARATUS

The present invention relates to a printing method and apparatus, and in particular to a printing method and apparatus suitable for printing on the external surface of a three-dimensional object.

The invention employs the known process of surface water printing, in which the image to be printed on the three-dimensional object is supplied on a pre-printed water-soluble film, such as PVA. The ink itself is water-insoluble. The water-soluble film is floated on the surface of a tank of water, which causes the film to dissolve, releasing the ink which would remain floating on the water surface. An activator may be employed to speed up the process. As the film is dissolving and while the ink molecules are still being held in position by the dissolving film, the object is immersed in the water, through the ink layer and through the dissolving film layer. The pressure of the water causes the ink to contact and adhere to the immersed three-dimensional surface of the object. The object can then be removed from the tank, and cleaned, dried and lacquered as required.

The surface water printing process has been used successfully to impart visual or textural qualities to the surface of three-dimensional objects. For example, the process has been used to alter the appearance and/or feel of an object formed from one material such that it appears to be formed from a different material. Examples are the application of a wood-grain effect to the surface of an object which is formed from a plastics material, or providing an object formed from a metal such as aluminium with the external appearance of leather or suede . The printing process to which the invention relates is applicable to virtually any size and type of three- dimensional object. The only requirement is that the object is suitable for use in the process, and the object should therefore be capable of immersion in a liquid. Suitable three-dimensional objects may include general promotional products, housings or cases for consumer electronic products (e.g. mobile phones or pagers), toys, automotive products (e.g. vehicle dashboards), and even vehicle bodies. Consequently, there is a vast range of applications for this three- dimensional printing process.

The above-mentioned surface water printing process is normally used for imparting patterns or textures to the surface of a three-dimensional object. This process is not normally used simply to paint the surface of an object in a single colour, as this can be achieved by conventional painting processes which are relatively cheaper. For example, when providing an object with a wood grain effect, a typical production process would be to spray-paint the object in the base colour (which may be brown in this case) . The grain effect can then be added using the surface water printing process detailed above. However, it will be appreciated that the printing process to which the present invention relates is suitable for any type of surface treatment of a three-dimensional object, including the application of a single colour.

The above-described printing process has been very effective for surface treatment of three-dimensional articles, but there are a number of disadvantages and improvements which could be made.

Firstly, the images which can be applied by the prior art process have to be random in nature, because it is not possible accurately to register the image with the object. One reason for this is that the positioning of the image on the pre-printed PVA rolls is fixed and therefore cannot be controlled during the product printing process. Consequently, it is difficult accurately to position the image on the water surface with reference to the object position. These disadvantages mean that images or indicia which need to be accurately located on an object, such as the manufacturer's name or trade mark, or an image which is designed specifically to match the object contours, cannot be printed onto the object with this system. With the example of the addition of a manufacturer's name or trade mark, the object surface may be decorated with a random pattern using the prior art process, but a separate subsequent step is required to add the manufacturer's name, by adding a transfer, or by a separate printing process, for example.

The second disadvantage with the known system is that product decorators need to stock a relatively large number of pre-printed water-soluble film rolls if they are to be able to react quickly to customer demands. In reality, this is not possible due to space constraints and economies of scale. Therefore, the known process is suitable only for a relatively limited number of high- volume designs.

There is therefore a need for a printing system which can apply images to three-dimensional objects with a high degree of accuracy. There is also a need for a more flexible printing system which can produce smaller numbers of objects, or even one-offs, having a larger number of possible designs, or an individual design, in a shorter space of time.

According to one aspect, the invention provides a method of printing an image on a three-dimensional object, in which ink in the configuration of the image is applied to a water-soluble film in an on-line process prior to the application of the image to the object, which application is carried out by floating the film, ink uppermost, on water such that the film begins to dissolve and by immersing the object in the water, through the ink and dissolving film layers, such that the pressure of the water causes the ink to contact and adhere to the three-dimensional surface of the object.

According to another aspect, the invention provides apparatus for printing an image on a three-dimensional object, comprising means for applying ink in the configuration of the image to a water-soluble film, and means for containing water, wherein, in use, the film is floated ink uppermost on the surface of the water such that the film begins to dissolve, the apparatus further comprising means for lowering the object into the containing means.

The present invention provides a printing system which is more flexible than the prior art system. By applying the image to the water-soluble film in an on- line process prior to applying the image to the object, the exact location of the image relative to the object can be controlled and maintained. This therefore provides a greater degree of accuracy not previously attainable with this process, and makes possible the application of any image which requires precise location on the object, such as images including names, logos, trade marks, labels or other indicia. In the case of applying a visual surface treatment to the object, the system of the present invention allows the addition of other information to the image, such as the manufacturer's name, before the combined image is applied to the water-soluble film. It is envisaged that the on-line printing of the water-soluble film may be carried out a number of times before one or more objects are printed. This would allow multiple images to be applied to the film before a number of objects are printed simultaneously, or in succession, for example. Preferably, however, the image is applied to the film immediately prior to the printing of the object.

The printing system of the invention makes possible the production of individual or one-off designs, as well as relatively small numbers. This is due to the fact that the on-line printing of the water-soluble film allows the design to be changed almost immediately. Sudden changes in production requirements can therefore be easily accommodated. It is therefore not necessary for the product decorator to hold a large stock of preprinted films. In fact, it is not necessary for the decorator to hold any pre-printed film stocks at all.

It will be appreciated that the present invention is not limited to any one particular application, but is suitable for all shapes and sizes of object and all types of printing and surface decoration. The word "image" should therefore be construed broadly, and should even encompass a single colour or shading.

It is envisaged that the means for applying ink to the water-soluble film may comprise any suitable printer or printing process. In order to allow compatibility with an image which is in bitmap form, such as an image which has been created on a computer for example, the means for applying ink to the water-soluble film is preferably a digital printer, such as an inkjet printer for example. An inkjet printer has been found to be very suitable for use with the surface water printing process and with the particular types of inks employed. An inkjet printer also provides a high degree of flexibility when producing a variety of different images and allows the chosen image to be printed on the water- soluble film almost instantaneously once the image has been chosen or completed.

As mentioned above, the ink should be water- insoluble .

The apparatus preferably further comprises means for controlling the means for applying ink, such as a computer. The means for controlling the means for applying ink may hold a database of available images, as well as any necessary image-processing software to allow the chosen image to be sent to the printer in a suitable form for printing. The means for controlling may also include software to allow an image to be created onscreen. In addition, scanning means may also be provided to allow an image to be scanned into the means for controlling, for processing and sending to the printer.

It is envisaged that the water-soluble film may be provided on a roll, and that sufficient film is unrolled prior to the application of the ink. Alternatively, the film may be unrolled whilst the ink is being applied to it. Once the ink application process has been completed, the printed film may then be cut from the stock roll and transferred to the means for containing water, which is preferably a tank.

However, the water-soluble film is preferably mounted in a carriage means, such as a frame. This is a new departure, and according to another aspect, the invention provides a method of printing an image on a three-dimensional object, in which ink in the configuration of the image is provided on a water- soluble film which is mounted in a carriage means, the image being applied to the object by floating the film, ink uppermost, on water such that the film begins to dissolve and by immersing the object in the water, through the ink and dissolving film layers, such that the pressure of the water causes the ink to contact and adhere to the three-dimensional surface of the object.

The invention also provides apparatus for printing an image on a three-dimensional object, comprising carriage means for carrying a water-soluble film having ink in the configuration of the image provided thereon, and means for containing water, wherein, in use, the film is floated ink uppermost on the surface of the water such that the film begins to dissolve, the apparatus further comprising means for lowering the object into the containing means.

The apparatus may further include a plurality of carriage means or frames, each containing a sheet of water-soluble film, which are stored in a magazine.

The carriage means or frame greatly improves the handling of the water-soluble film, and allows the exact position of the film to be determined, both during the on-line film printing process if employed, and most importantly during the application of the image to the object. The image on the film is therefore in a known fixed relationship with the carriage means, and accurate registration with the object can be achieved.

Consequently, it is possible to print objects with images which are configured specifically for that object, e.g. non-random images which must be placed in a specific position on the object, or images which include relief- or contour-related features, names, trade marks or logos, etc. This aspect is also a new departure, and therefore the invention also provides a method of printing an image on a three-dimensional object, the image being specifically configured in relation to the object to be printed, in which ink in the configuration of the image is provided on a water-soluble film, the image being applied to the object by floating the film, ink uppermost, on water such that the film begins to dissolve and by immersing the object in the water, through the ink and dissolving film layers, such that the pressure of the water causes the ink to contact and adhere to the three-dimensional surface of the object.

The invention also provides apparatus for printing an image on a three-dimensional object, the image being specifically configured in relation to the object to be printed, wherein ink in the configuration of the image is provided on a water-soluble film, the apparatus comprising means for containing water, wherein, in use, the film is floated ink uppermost on the surface of the water such that the film begins to dissolve, the apparatus further comprising means for lowering the object into the containing means.

As mentioned above, the specifically-configured image may include features which must appear in a specific location on the object, such as relief- or contour-related features, labels, names, trade marks or logos, etc. The image may alternatively or in addition be a non-random image which is designed to appear in a specific position on the object. The image may also or alternatively be provided with blank areas corresponding to areas on the object where printing is not desired.

Another type of specifically-configured image is one which has been designed to reduce or minimise image stretch when applied to the object. If a surface of the object contacts the ink with a relatively oblique angle of immersion (e.g. between 45° and 90° to the plane of the ink) , a given amount of ink will be spread over a greater area than for a surface which contacts the ink with a relatively acute angle of immersion (e.g. between 0° and 45° to the plane of the ink) . This will result in parts of the image appearing to be distorted or stretched. Any angle of immersion over 0° will result in image stretching to some extent, but the effect will clearly become greater as the angle of immersion increases. In some images, the effect may not be particularly noticeable, particularly if the image is random in nature, and therefore can be tolerated. In other images where a uniform pattern or appearance is desired, however, it is advantageous to avoid this stretching effect.

In accordance with another aspect, therefore, the present invention provides a method of printing an image on a three-dimensional object, comprising the steps of: providing an image which is dependent on at least some of the contours of the three-dimensional object, applying ink in the configuration of the contour- dependent image to a water-soluble film, and applying the image to the object by floating the film, ink uppermost, on water such that the film begins to dissolve and by immersing the object in the water, through the ink and dissolving film layers, such that the pressure of the water causes the ink to contact and adhere to the three-dimensional surface of the object.

The invention also provides apparatus for printing an image on a three-dimensional object, comprising: means for providing an image which is dependent on at least some of the contours of the three-dimensional object, means for applying ink in the configuration of the contour-dependent image to a water-soluble film, and means for containing water, wherein, in use, the film is floated ink uppermost on the surface of the water such that the film begins to dissolve, the apparatus further comprising means for lowering the object into the containing means.

In a preferred embodiment, the means for providing the contour-dependent image adjusts the image to compensate for image stretch or distortion (discussed above) . Preferably, the image to be applied to the object is initially provided in bitmap form, and the contour- ependent image can then be derived from this bitmap and from contour information for the object to be printed. The means for providing the contour-dependent image therefore preferably comprises a processing means, such as a computer.

The apparatus preferably further includes means for positioning the water-soluble film, and the or each carriage means or frame if present, during use of the apparatus. This may be conventional means employing one or more motors in conjunction with positioning members. It would also be within the scope of the skilled person to adapt a CNC or robotic system to handle and position the water-soluble film.

The apparatus preferably further comprises means for positioning the object to be printed. This may be the same means as the means for lowering the object into the water, mentioned above. Again, this may be conventional means employing one or more motors in conjunction with positioning members, or a CNC or robotic system.

It is preferable that the positioning of the object is as accurate as possible, particularly during the surface water printing stage when the object is lowered into the water. It is desirable to immerse the object in the water at an angle which avoids the formation of air locks or air bubbles on the exterior surface of the object. The particular angle will clearly depend on the surface configuration of the object being printed, but for simple objects having generally planar sides, it is preferable that all sides are at an angle to the surface of the water which allows the water (and therefore the ink) to gradually coat that surface. The speed of immersion also needs to be carefully controlled so that the ink suspension on the surface of the water is not disturbed until it contacts the object. For these reasons, the use of a computer-controlled or robotic positioning system for the object is to be preferred.

The object to be printed may be mounted directly to the means for positioning, or may be mounted to it by means of a jig or nest. The means for positioning may be adapted to immerse the object into the water at a suitable angle, as discussed above. Alternatively, the jig or nest may have the appropriate immersion angle built-in, and therefore the means for positioning will simply need to move the object vertically into the water at the appropriate speed.

Preferably, the apparatus further comprises means for cleaning the object prior to printing on the surface of the object. The object may be cleaned through the use of air under pressure, or through the use of water or other solvent, which may be applied through one or more jets. Preferably, the means for cleaning the object comprises a container which in use contains water, together with means for applying ultrasonic waves in use to the water and to the object being cleaned.

The ultrasound causes cavitation of the fluid, and thus a more efficient cleaning action. Preferably, the container is sealed during the application of the ultrasound. This may be achieved by sealing means being present between the container and the means for positioning the object, or the jig or nest, such that a hermetic seal is achieved.

The apparatus may include means for pre-treating the surface of the object prior to printing. The purpose of such pre-treatment may be to increase the affinity between the ink and the surface, or improve adhesion of the ink to the surface. In one aspect, the pre-treatment comprises roughening of the object surface, for example by the use of a corona discharge or flame treatment. These treatments abrade the surface of the object on a relatively small scale, which allows better wetting of the surface by the ink. Another pre- treatment is to employ a solvent wipe/rinse process, in which the solvent causes softening of the surface of the object, which again allows better surface penetration by the ink.

It is also possible to use the same processes described above to pre-treat the film on which the ink is initially provided, such that on contact with the water (and optionally any activator that may be present in the water) , the film dissolves more readily by virtue of the increased surface roughness or softness .

Once the object has been printed, traces of the water-soluble film may still be present on the surface of the object, and therefore the apparatus preferably further comprises means for cleaning the object after printing. This may be the same cleaning means as that which cleans the object prior to printing, or alternatively may comprise a further container provided with water jets directed at the object. Once the object has been cleaned, whether prior to or after printing, it is preferable that the object is dried. Preferably, therefore, the apparatus further comprises means for drying the object, which in its most preferred form comprises vacuum-drying means.

As mentioned above, it is preferable to apply a protective coating, e.g. lacquer, to the printed object. Therefore, the apparatus preferably further comprises means for applying a protective coating to the printed object. It is envisaged that the means for applying the protective coating may comprise spraying means. Preferably, however the means for applying the protective coating comprises a container for containing the protective coating (in liquid form) , the object in use being immersed into the liquid protective coating and withdrawn such that a covering is applied to the object surface. The speed with which the object is withdrawn determines the thickness of the coating. The apparatus preferably also comprises a plurality of means for applying the protective coating, each means being adapted to apply a different coating to the object. For example, different coatings may be desired to impart different surface textures or appearances, such as gloss, satin or matt finishes, and the appropriate means may be selected depending on production requirements without any substantial reconfiguration of the apparatus. Where the means for applying the protective coating is a container, for example, a plurality of such containers may be provided, and the means for positioning the object can be programmed to select the appropriate container during production.

The protective coating may be polyurethane or acrylic lacquer, and may be heat- or ultraviolet- curable. The coating may be designed to achieve a matt, satin, gloss, wet look, soft feel or textured finish. If the coating is ultraviolet-curable, the apparatus preferably further comprises means for applying ultraviolet radiation to the object.

The apparatus may be provided in modular form, with individual modules performing the various functions described above. This allows flexibility when configuring the apparatus for a specific application.

The applicants envisage that the present invention has application not only in industry during the manufacture or production of products, but also in retail outlets. For example, the printing apparatus could be located in a shop selling particular three- dimensional products, and the customer would be able to specify a particular image, perhaps from viewing a library of designs available or even by producing a design to his own specification, and then the object can be coated with that image while the customer waits . This therefore reduces the stocks which a shop needs to hold, but allows a high degree of personalisation for the customer.

It can be seen that the printing system of the present invention is extremely flexible, and can be used to apply any colour, pattern, design, picture, text or texture to the three-dimensional surface of an object, as well as a protective top coat. The printing apparatus is designed to be self-contained and to carry out all the functions necessary to apply the chosen image to the object.

Reference to the use of water in the printing process is made throughout the specification. This term is, however, intended to cover any liquid suitable for use in the process, and therefore the terms "water", "water-soluble" and "water- insoluble" should be construed accordingly.

The present invention will now be described by way of example only and with reference to the accompanying drawings, in which:

Fig. 1 shows a plan view of the apparatus in accordance with the invention;

Fig. 2 shows a cross-sectional view along line 2-2 of Fig. 1; Fig. 3 shows an isometric view of the apparatus as viewed from the rear;

Fig. 4 shows an isometric view of the apparatus as viewed from the front;

Fig. 5 shows cleaning station 60 in more detail; Fig. 6 shows drying station 70 in more detail;

Figs. 7A, 7B and 7C show printing station 80 and the printing operation in more detail;

Fig. 8 shows lacquering station 90 in more detail ,- Fig. 9 shows curing station 100 in more detail; Fig. 10 shows schematic representations of a mobile phone bezel as employed in the image stretch compensation process; and

Fig. 11 shows a flowchart of the image stretch compensation process.

A printing apparatus in accordance with the invention is shown schematically in Figs. 1 to 4 as 10. The apparatus comprises a number of stations 30, 40, 60, 70, 80, 90 and 100 which are enclosed in the apparatus housing 11. The printing process is designed to be as automated as possible, with the main operator tasks being the selection of an image to be applied to the product and the loading/unloading of the product . The apparatus is controlled by means of control panel 12 (Fig. 4) . The product to be printed enters and exits the apparatus through aperture 13. Referring to Fig. 1, once the chosen image has been selected, computer 20 formats the image for application to the product . Image stretch compensation will be discussed later with reference to Figs. 10 and 11. Once any image stretch compensation has been carried out, and the image has been formatted into a form suitable for the printer, the data is sent to the printing station shown schematically as 30. The printing station 30 comprises an inkjet printer.

A frame containing an unprinted clear PVA film is removed from the magazine shown schematically as 40 and is passed through printing station 30, under the inkjet printhead, on a carrier table 41. The selected image is then applied to the PVA film by conventional techniques. Once the film has been printed in this way, the image is ready to be applied to the product.

With reference to Fig. 2, the product 50 to be printed is mounted by the operator onto a CNC nest 51 which securely locates and holds the product. This nest is configured to provide the required immersion angle for the product. The nest 51 is then attached to a jig 52, and the jig, nest and product are fed through the loading aperture 13 and attached to the fixing plate 53. This entire assembly is movable in the vertical plane by means of motor 54, and is also movable in the horizontal plane by additional motors and by means of an overhead gantry system 55 as shown in Figs. 2 and 3. The motors and gantry system are arranged such that the product can be moved between stations 60, 70, 80, 90 and 100 as shown in Figs . 1 to 4.

The first stage in the process of applying the image to the product 50 is the cleaning of the product, which is carried out in cleaning station 60. This station is shown in more detail in Fig. 5, and comprises a tank 61 which is initially filled with water. The product 50 is lowered into the tank 61 such that the jig 52 makes a hermetic seal with the side walls of the tank 61 by means of a gasket 62 which is situated around the rim of the tank. Ultrasonic waves 63 are then applied to the product and the water by means of an ultrasonic transducer 64, and the resulting cavitation of the water produces an effective cleaning action to remove any dust or debris on the product 50. Once the ultrasound has been applied for a sufficient time, the jig 52 is raised and transferred to drying station 70 (Fig. 6) . Again, a seal is created between the jig 52 and the rim of container 71 by means of gasket 72, and a vacuum is created inside the tank 71 in order to remove any moisture from the surface of the product 50.

The next stage in the process is the printing of the product 50, which takes place in printing station 80 (Fig. 7). With reference to Fig. 7A, the printing station comprises a tank 81 which is initially filled with water 82. In order to reduce the process time, the water is preferably warm, e.g. about 30°C. The previously-printed PVA film 83 (dashed line) which is held in frame 84 is lowered by carrier table 41 onto the top of tank 81, such that the film 83 rests on the surface of the water 82. The film is lowered at a slight angle so that air bubbles are prevented from forming between the film and the water surface. The frame 84 may also be provided with holes to allow the air to escape from underneath the film.

As soon as the PVA film 83 contacts the water 82, it begins to dissolve, leaving a layer of ink 85 (dotted line) floating on the water surface. At the correct moment, when the film has become sufficiently softened and flexible, but whilst the ink 85 is still being held in position on the surface of the water, the product 50 is lowered into the tank 81 through the ink layer 85 and the layer of dissolving film 83 (Fig. 7B) . The pressure of the water on all surfaces of the product 50 forces the ink around the product and into contact with the surface, thereby applying the pattern to all surfaces of the three-dimensional product, irrespective of their orientation.

As with the placement of the film 83 on the water surface, the product 50 is also immersed at such an angle so that air is not trapped in any relief features of the product. This ensures that the entire immersed surface of the product is covered by the ink 85. The angle of immersion will depend on the particular contours of the product being printed, and as discussed above, the nest 51 is configured to have the appropriate angle of immersion built-in, so that the orientation of jig 52 or plate 53 does not have to be altered if different products are being printed.

Once the product 50 has been immersed as far as is desired, the water is then allowed to drain from the tank 81 (Fig. 7C) . The product 50 is then washed with water (also preferably warm) from jets provided in the sides and the base of the tank (not shown) , so as to remove the remaining deposits of the PVA film carrier.

From printing station 80, the product is then moved back to drying station 70 (Fig. 6) for vacuum drying as before.

The next stage in the process is the application of a protective coat of lacquer to the product, which takes place in lacquering station 90, which comprises a tank 91 containing lacquer 92 (Fig. 8) . As previously mentioned, the apparatus may include a number of such tanks, e.g. to enable the application of gloss, matt or satin lacquer, or other textured coating, depending on requirements. In the described embodiment, an ultraviolet-curable lacquer is employed. The product is lowered into the lacquer, and is the withdrawn at a controlled speed. The speed determines the thickness of the lacquer coating; the slower the speed, the thicker the coating, and therefore the speed is selected appropriately. The product 50 and jig 52 are then transferred to curing station 100 (Fig. 9) where the lacquer is cured by the application of ultraviolet radiation from ultraviolet sources 101.

Finally, the jig 52, nest 51 and coated product 50 are returned to aperture 13 where they may be detached from the plate 53 by the operator.

Referring to Figs. 10 and 11, the processing of the desired image to compensate for image stretch will now be described. One of the many products for which the present invention may be used is a mobile phone bezel. For simplification, a mobile phone bezel may be considered as a generally planar rectangular surface together with four further generally planar surfaces extending perpendicularly therefrom. Each planar surface is connected to the other by a radial surface which smoothes the 90° transition.

With reference to Fig. 10A, the "surface zone" of a mobile phone bezel is shown, in which all the surfaces (and radii) are shown in one plane but in their true relative areal proportions. The surface zone comprises front panel 200a, side panels 201a and radii 202a. Corner areas 203a are not shown in correct proportion in the Figure. The surface zone therefore represents the area of the image which is to be applied to the bezel in its undistorted form. For a particular product being printed, a "distortion matrix" is obtained which is derived from the product shape and which contains information about which areas will distort the image and by how much when an image is applied by the process described above. In order to compensate for image stretch, a "distortion zone" is created, as shown in Fig. 10B, which is effectively a representation of the bezel as viewed from the "immersion plane", i.e. the plane of the ink. The distortion zone represents the area of ink that will actually be applied to the bezel during immersion. The area of front panel 200b in Fig. 10B is the same as that of front panel 200a in Fig. 10A, because there is no image distortion for this panel. However, it can be seen that for an unstretched image to appear on side panels 201a, that area of image must be compressed into narrow areas 201b in Fig. 10B, since the side panels and corner panels are substantially perpendicular to the plane of the ink. The stretching effect which will occur during printing will then reverse the compression applied to the image, such that the correct, unstretched image is applied to all surfaces of the product, irrespective of their orientation relative to the surface of the ink.

Figure 10C shows a cross-section through the bezel. For radial area 202c, the distortion matrix will compress the image data with a variable factor, starting from zero compression where the radius joins with front panel 200c, up to a constant compression where it joins with side panel 201c. The compression for planar side panel 201c will be constant.

The image processing for corner areas 203 is slightly more complex, as compression in more than one direction is required. However, the required image distortion is provided in the distortion matrix and is applied to the image as for the other panels.

The distortion of the image is carried out most easily through the use of a proprietary image processing software package, such as Adobe Photoshop. The image to be applied to the product is loaded into the software program in the form of a bitmap, and the distortion matrix discussed above is then used to create a filter which applies the required distortion to the image so as to compensate for image stretch. The distortion can be carried out on a bit-by-bit basis. The resulting image, or "bezel distorted image" can then be sent directly to the PVA film printer for application to the product. The various stages of the image distortion compensation process are shown in Fig. 11 as a flow chart.

Claims

Claims :

1. Apparatus for printing an image on a three- dimensional object, comprising means for applying ink in the configuration of the image to a water-soluble film, and means for containing water, wherein, in use, the film is floated ink uppermost on the surface of the water such that the film begins to dissolve, the apparatus further comprising means for lowering the object into the containing means.

2. Apparatus as claimed in claim 1, wherein the water- soluble film is provided on a roll prior to the ink being applied thereto.

3. Apparatus as claimed in claim 1, wherein the water- soluble film is mounted in a carriage means.

4. Apparatus for printing an image on a three- dimensional object, comprising carriage means for carrying a water-soluble film having ink in the configuration of the image provided thereon, and means for containing water, wherein, in use, the film is floated ink uppermost on the surface of the water such that the film begins to dissolve, the apparatus further comprising means for lowering the object into the containing means.

5. Apparatus as claimed in claim 3 or 4 , wherein the apparatus further includes a plurality of carriage means, each containing a sheet of water-soluble film, which are stored in a magazine.

6. Apparatus for printing an image on a three- dimensional object, the image being specifically configured in relation to the object to be printed, wherein ink in the configuration of the image is provided on a water-soluble film, the apparatus comprising means for containing water, wherein, in use, the film is floated ink uppermost on the surface of the water such that the film begins to dissolve, the apparatus further comprising means for lowering the object into the containing means.

7. Apparatus for printing an image on a three- dimensional object, comprising: means for providing an image which is dependent on at least some of the contours of the three-dimensional object , means for applying ink in the configuration of the contour-dependent image to a water-soluble film, and means for containing water, wherein, in use, the film is floated ink uppermost on the surface of the water such that the film begins to dissolve, the apparatus further comprising means for lowering the object into the containing means.

8. Apparatus as claimed in claim 7, wherein the means for providing the contour-dependent image adjusts the image to compensate for image stretch or distortion.

9. Apparatus as claimed in claim 7 or 8 , wherein the image to be applied to the object is initially provided in bitmap form, the contour-dependent image being derived from the bitmap and from contour information for the object to be printed.

10. Apparatus as claimed in claim 7, 8 or 9 , wherein the means for providing the contour-dependent image comprises a processing means, which is preferably a computer.

11. Apparatus as claimed in any preceding claim, wherein the means for applying ink to the water-soluble film is a digital printer.

12. Apparatus as claimed in any preceding claim, wherein the means for applying ink to the water-soluble film is an inkjet printer.

13. Apparatus as claimed in any preceding claim, further comprising means for controlling the means for applying ink, which is preferably a computer.

14. Apparatus as claimed in claim 13, wherein the means for controlling the means for applying ink includes image-processing software to provide the image in a form suitable for printing.

15. Apparatus as claimed in claim 13 or 14, further comprising scanning means to allow an image to be scanned into the means for controlling.

16. Apparatus as claimed in any preceding claim, further comprising means for positioning the water- soluble film during use of the apparatus.

17. Apparatus as claimed in any preceding claim, further comprising means for positioning the object to be printed.

18. Apparatus as claimed in claim 16 or 17, wherein the means for positioning the film and/or object comprises a computer-controlled or robotic positioning system.

19. Apparatus as claimed in any preceding claim, further comprising means for cleaning the object.

20. Apparatus as claimed in claim 19, wherein the means for cleaning the object comprises a container which in use contains water, together with means for applying ultrasonic waves in use to the water and to the object.

21. Apparatus as claimed in any preceding claim, further comprising means for drying the object.

22. Apparatus as claimed in any preceding claim, further comprising means for applying a protective coating to the printed object.

23. Apparatus as claimed in any preceding claim, further comprising means for pre-treating the surface of the object prior to printing.

2 . Apparatus as claimed in any preceding claim, further comprising means for pre-treating the surface of the film prior to printing.

25. Apparatus as claimed in claim 23 or 24, wherein the means for pre-treating comprises a corona discharge unit, a flame treatment unit, or a solvent wipe/rinse unit .

26. Apparatus as claimed in any preceding claim, wherein the apparatus is provided in modular form.

27. A method of printing an image on a three- dimensional object, in which ink in the configuration of the image is applied to a water-soluble film in an online process prior to the application of the image to the object, which application is carried out by floating the film, ink uppermost, on water such that the film begins to dissolve and by immersing the object in the water, through the ink and dissolving film layers, such that the pressure of the water causes the ink to contact and adhere to the three-dimensional surface of the object .

28. A method of printing an image on a three- dimensional object, in which ink in the configuration of the image is provided on a water-soluble film which is mounted in a carriage means, the image being applied to the object by floating the film, ink uppermost, on water such that the film begins to dissolve and by immersing the object in the water, through the ink and dissolving film layers, such that the pressure of the water causes the ink to contact and adhere to the three-dimensional surface of the object.

29. A method of printing an image on a three- dimensional object, the image being specifically configured in relation to the object to be printed, in which ink in the configuration of the image is provided on a water-soluble film, the image being applied to the object by floating the film, ink uppermost, on water such that the film begins to dissolve and by immersing the object in the water, through the ink and dissolving film layers, such that the pressure of the water causes the ink to contact and adhere to the three-dimensional surface of the object.

30. A method of printing an image on a three- dimensional object, comprising the steps of: providing an image which is dependent on at least some of the contours of the three-dimensional object, applying ink in the configuration of the contour- dependent image to a water-soluble film, and applying the image to the object by floating the film, ink uppermost, on water such that the film begins to dissolve and by immersing the object in the water, through the ink and dissolving film layers, such that the pressure of the water causes the ink to contact and adhere to the three-dimensional surface of the object.

31. The method as claimed in claim 30, wherein the contour-dependent image is provided by adjusting the image to compensate for image stretch or distortion.

32. The method as claimed in claim 30 or 31, wherein the image to be applied to the object is initially provided in bitmap form, the contour-dependent image being derived from the bitmap and from contour information for the object to be printed.

33. The method as claimed in any of claims 27 to 32, further comprising the step of scanning an image prior to the application thereof to the film.

34. The method as claimed in any of claims 27 to 33, further comprising the step of cleaning the object prior to and/or after printing.

35. The method as claimed in claim 34, further comprising the step of drying the object after cleaning.

36. The method as claimed in any of claims 27 to 35, further comprising the step of applying a protective coating to the object after printing.

37. The method as claimed in any of claims 27 to 36, further comprising the step of pre-treating the surface of the object prior to printing.

38. The method as claimed in any of claims 27 to 37, further comprising the step of pre-treating the surface of the film prior to printing.

39. The method as claimed in claim 37 or 38, wherein the pre-treating comprises employing a corona discharge, treating the surface with a flame, or employing a solvent .