LINERLESS LABEL IMAGING AND CUTTING

Abstract

A method and apparatus for imaging, cutting and applying a linerless label substrate 2. The substrate 2 is transported to an imaging area and is selectively illuminated by a suitable laser to form an image. By determining the position of the edge of the image, further laser illumination is used to cut the label substrate thereby providing a single label for application to an object. In this manner, the method of the present invention provides all the benefits of a linerless labelling system plus enables flexibility in printing labels of different sizes.

Claims

1-40. (canceled)

41. A method of printing and cutting a label for application to a product, the method comprising the steps of: providing a strip of linerless label substrate, the label substrate comprising a colour change layer; selectively exposing a section of the linerless label substrate to laser radiation to induce colour change in the colour change layer and thereby form a printed image; determining the position of the edge of the printed image; and cutting the linerless label substrate using a laser in response to the determined position of the edge of the printed image.

42. A method as claimed in claim 41 wherein the method includes the additional step of applying a cut and printed label to an object.

43. A method as claimed in claim 41, wherein the laser illumination operates at a higher power level during cutting.

44. A method as claimed in claim 41 wherein the step of cutting involves cutting through the full thickness of the substrate; or involves cutting through only part of the thickness of the substrate; or involves cutting part way across the width of the label substrate; or involves cutting a series of perforations across the full width of the label substrate.

45. A method as claimed in claim 41 wherein the substrate comprises a base layer having an adhesive layer provided on one side and colour change layer covered by a release layer on the other side or wherein the substrate comprises a base layer having a release layer provided on one side and colour change layer covered by an adhesive layer on the other side.

46. A method as claimed in claim 45 wherein an NIR (near infra red) absorber is added to the base layer and/or the colour change layer.

47. A method as claimed in claim 45 wherein the colour change layer comprises a metal oxyanion, a leuco dye, a diacetylene, a charge transfer agent or a diacetylene.

48. A label printing and cutting apparatus suitable for use with a strip of linerless label substrate, the label substrate comprising a colour change layer in which a printed image may be formed, the apparatus comprising: a label store for retaining and supplying a strip of label substrate; transport means for transporting label substrate from the store to an imaging area; a position sensor for determining the position of the edge of the printed image; and laser illumination means operable to selectively illuminate the label substrate as it is transported through the imaging area so as to induce colour change in the colour change layer thereby forming the printed image, the laser illumination means further operable to cut the label substrate as it is transported through the imaging area in response to the position sensor.

49. A label printing and cutting apparatus as claimed in claim 48 wherein the laser illumination means comprise a laser array or an array of fibres coupled to lasers.

50. A label printing and cutting apparatus as claimed in claim 48 wherein the laser illumination means comprise separate printing and cutting lasers.

51. A label printing and cutting apparatus as claimed in claim 48 wherein the laser illumination means comprises a single laser.

52. A label printing and cutting apparatus as claimed in claim 50 wherein the laser illumination means has a printing mode and a cutting mode and the laser illumination means operates at a higher power level in cutting mode than printing mode.

53. A label printing and cutting apparatus as claimed in claim 52 wherein the laser illumination means is operable, in cutting mode, to: cut through the full thickness of the substrate in cutting mode; or cut through only part of the thickness of the substrate; or cut part way across the width of the label substrate; or cut a series of perforations across the full width of the label substrate.

54. A label printing and cutting apparatus as claimed in claim 48 wherein the laser illumination means has an operating wavelength in the range 200 nm to 20 m or wherein the laser illumination means has a wavelength in the range 390-450 nm.

55. A label printing and cutting apparatus as claimed in claim 48 wherein the position sensor comprises an optical sensor operable to determine the location of the edge of the image by: directly detecting an edge of the image; or by detecting a registration mark identifying the edge of the image.

56. A label printing and cutting apparatus as claimed in claim 48 wherein the position sensor comprises a transport sensor monitoring operation of the transport means to determine, based on the size of the printed image and the operation of the transport means, the location of the edge of the printed image

57. A label printing and cutting apparatus as claimed in claim 48 wherein the substrate comprises a base layer having an adhesive layer provided on one side and colour change layer covered by a release layer on the other side or wherein the substrate comprises a base layer having a release layer provided on one side and colour change layer covered by an adhesive layer on the other side.

58. A label printing and cutting apparatus as claimed in claim 57 wherein an NIR (near infra red) absorber is added to the base layer and/or the colour change layer.

59. A label printing and cutting apparatus as claimed in claim 57 wherein the colour change layer comprises a metal oxyanion, a leuco dye, a diacetylene, a charge transfer agent or a diacetylene

Description

DETAILED DESCRIPTION OF THE INVENTION

[0034] In order that the invention may be more clearly understood an embodiment thereof will now be described, by way of example only, with reference to the accompanying drawings, of which:

[0035] FIG. 1 is a schematic illustration of a linerless label substrate for use in the present invention;

[0036] FIG. 2 is a schematic illustration of a label printing and cutting apparatus for a linerless label substrate according to the present invention; and

[0037] FIG. 32 is a schematic illustration of an alternative embodiment of a label printing and cutting apparatus for a linerless label substrate according to the present invention.

[0038] The present invention discloses a method and apparatus for imaging, cutting and applying a label to a package or product. In particular the present invention discloses a method and apparatus for imaging, cutting and applying a linerless label substrate 2 as shown in FIG. 1. The label substrate 2 comprises a base layer 21, a colour change layer 22, an adhesive layer 23, and a release layer 24. The base layer 21 may comprise paper or a polymeric film such as polypropylene. The colour change layer 22 incorporates a colour change compound operable to change colour in response to illumination by light from a suitable laser. The adhesive layer 23 comprises adhesive which allows the label 2 to adhere to an object. The release layer 24 comprises a material adapted to have low adherence to the adhesive layer 23. In this manner, the label substrate 2 may be wound on and dispensed from a reel.

[0039] In the method of the present invention, the substrate 2 is transported from a storage reel to an imaging area. At the imaging area, the label substrate 2 is selectively illuminated by a suitable laser to form an image in the colour change layer 22. By determining the position of the edge of the image, further laser illumination may be used to cut the label substrate thereby providing a single label for application to an object. In this manner, the method of the present invention provides all the benefits of a linerless labelling system plus enables flexibility in printing labels of different sizes.

[0040] Turning now to FIGS. 2 and 3, apparatus for carrying out the method of the present invention is illustrated schematically. A reel 1 is wound with a strip of label substrate 2, the reel 1 being supported on a spindle (not shown). The label substrate 2 is pulled forward from the reel 1 by a transport means 3 comprising a roller, rollers (FIG. 2) or belt (FIG. 3). A brush 4 is located at the input end of the mechanism 3 and may be used to press the label substrate 2 onto a support belt or rollers 3. The brush 4 improves the uniform contact area and minimizes substrate distortion during illumination. Whilst brush 4 is beneficial, the skilled man will appreciate it is not essential to the operation of the invention. The label substrate 2 is arranged such that the adhesive layer 23 faces the support belt or rollers 3. In order that the support belt or rollers 3 provides sufficient tension to release the substrate 2 from the reel 1 but with low adhesion to the adhesive layer 23, the support belt or rollers 3 may be formed from silicone or other suitable material.

[0041] Whilst the label substrate 2 is supported on belt or rollers 3, it is selectively illuminated by a laser 10, within an imaging area 5 defined by scanning unit 9 (FIG. 2). Alternatively, the label substrate 2 is selectively illuminated by a laser array 100, within an imaging area 5 (FIG. 3). As a result of the illumination, an image is formed in the colour change layer 22 of the substrate. In some implementations, the illumination can take place whilst the substrate 2 is being transported. In other embodiments, illumination may take place whilst the substrate 2 is stationary or there may be a combination of moving and stationary illumination. Stationary illumination is particularly favoured with lasers and scanning units for printing bar codes and may be necessary to ensure any bar codes are of sufficient quality to ensure at least grade C, preferably grade B and preferentially grade A. Illumination whilst moving is typically sufficient for other text and/or graphics. A combination of imaging whilst moving for text and static for bar code provides minimum time for imaging with high quality barcodes.

[0042] After printing is complete, a cut is made across the substrate 2, so as to separate or provide a weakened region that is allows easy separation of an individual label from the substrate strip 2 for application to an object 7. The cut may completely separate the image from the remainder of the substrate. Alternatively, the cut may extend only partway across the substrate and/or comprise a series of perforations. The cut may also be a groove or channel that extends partway through the substrate.

[0043] In order to make the cut, the position of the edge of the printed image is determined. In the apparatus of FIG. 2, the position of the edge of the printed image is detected by optical sensor 12. This sensor can be operable in response to directly detecting the edge of the printed image. More preferably, the sensor 12 is operable to detect a registration mark printed during the selective illumination or an indentation in the substrate cut during illumination. In alternative embodiments it is however possible to monitor the movement of the support belt and use this in combination with knowledge of the size of the printed image to determine the position of the edge of the image.

[0044] In order to form a cut, the scan speed of the laser beam 10 is reduced by scanning unit 9 and/or the output power of laser 10 is increased. If a continuous laser beam is used, this results in cut across all or part of the width of the substrate 2. If however a pulsed laser beam is used, a series of perforations may be formed across the width of the substrate 2.

[0045] As is shown in FIG. 2, the cut is made in a cutting region A illuminated by beam path 6 at the exit end of the support belt or rollers 3. At this time the label substrate 2 protrudes beyond the end of the support belt or rollers 3 but is still supported by the support belt or rollers 3. Whilst the cutting operation could be performed anywhere within the imaging region 5, it is advantageous to provide the cutting region A beyond the support belt or rollers 3. As a result, undue and/or excessive wear or damage of the support belt or rollers 3 due to the incidence of the laser beam is avoided. The skilled man will however appreciate that similar benefits could be provided by ensuring the cutting region A is aligned with a gap between belts or rollers or if a suitable shield is provided to protect the belt or roller from the laser beam.

[0046] In the apparatus of FIG. 3, the position of the edge of the printed image is detected by monitoring the movement of the transport means 3 and using this in combination with knowledge of the size of the printed image to determine the position of the edge of the image. The output power of laser array 10 can then be increased, so as to form a cut. As is shown in FIG. 3, the cut is made in a cutting region A illuminated by beam path 6 between two rollers 3.

[0047] After cutting, the label is applied to an object 7 by applicator means. In the present example, the applicator means comprise a support roller 11 and a fixing roller 8 which presses the label onto the object 7. Where the cutting extends only part way through the thickness of the substrate, part way across the substrate or comprises a series of perforations, the apparatus may comprise a further separation means for separating the applied label from the remainder of the substrate. Alternatively, the cut or perforations may be adapted such that the separation occurs as a consequence of the strain on the label during the application process.

[0048] In a preferred implementation, the laser 10 is a CO2 laser which has been surprisingly found to enables the formation of clear printed images through release layer 24. Furthermore, the output of a CO2 laser is readily absorbed by the base layer 21 of the substrate 2. As such, the same laser 10 may be used for both imaging and cutting. Surprisingly, it has been found that use of the same laser to print an image and cut the substrate 2 does not result in significant discolouration at the cut edge of the substrate 2.

[0049] Typically, the normal CO2 laser wavelength is around 10.6 m and this is absorbed by many polymeric films and is adequate for cutting. However, this operating wavelength may be tuned for optimum absorption in the base layer 21 as this can reduce the laser fluence required for cutting. In the case of a polypropylene base layer 21, the absorption of polypropylene is significantly higher at 9.3 m and 10.3 m than it is at the usual operating wavelength for a CO2 laser (10.6 m). Accordingly, it is desirable, but not essential, to select an operating wavelength from the so called P and R vibrational bands of the CO2 molecule at 9.4 m and 10.4 m respectively.

[0050] 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 the appended claims.