GB2281054A

GB2281054A - Printing composite images

Info

Publication number: GB2281054A
Application number: GB9317122A
Authority: GB
Inventors: Roger E Wallis; Robert A Mackinnon
Original assignee: PERSTORP UNIDUR Ltd
Current assignee: PERSTORP UNIDUR Ltd
Priority date: 1993-08-17
Filing date: 1993-08-17
Publication date: 1995-02-22
Also published as: GB9317122D0; AU7392594A; WO1995005285A1

Abstract

Apparatus for printing a composite image, e.g. camouflage, comprises a plurality of elements carrying an image part having a respective length differing from one another, but not multiples of each other. A method of printing a composite image using the above apparatus is also disclosed. <IMAGE>

Description

"A method of and apparatus for printing" The present invention relates to a method of and apparatus for printing designs onto fabric and, more particularly, to a method of and apparatus for printing a random design onto a fabric and a method of and apparatus for printing a design having a long repeat pattern onto a fabric.

In some applications it is desirable to produce a design which either has a non-repeating pattern, i.e. a random pattern, or a pattern in which the repeating features are wide apart resulting in a pattern having a long design repeat. One particular application for a nonrepeating pattern, or a pattern in which the repeating features are much wider apart than in normal practice is in the production of printed camouflage. A non-repeating pattern, or a pattern with a long repeat length, makes visual and electronic recognition of such a design as a camouflage design more difficult.

Conventional printing processes used for continuous print production involve one or more print cylinders which continuously contact the material to be printed, with the cylinders (if more than one is provided) being of the same diameter so that the images printed by the different cylinders can be aligned. A continuously repeating pattern is printed onto the material, with the maximum repeat length of the pattern being equal to the circumference of the cylinder(s). Accordingly, a regularly repeating pattern is unavoidable when using a conventional continuous printing process.

The present invention provides an improved method and apparatus for printing.

In one aspect of the present invention there is provided a printing apparatus for printing a composite image, the apparatus comprising a plurality of printing elements, each printing element carrying an image part of the composite image to be printed, each image part having a respective repeat length, wherein the repeat lengths of the image parts are different from one another but not multiples of each other.

In a further aspect of the present invention there is provided a material carrying a composite image, the image comprising a plurality of image parts, wherein each image part has a respective repeat length, the repeat lengths of the image parts being different from one another but not multiples of each other.

In another aspect of the present invention there is provided a method of printing a composite image on a material, the composite image comprising a plurality of image parts, each image part having a repeat length, the repeat lengths of the image parts being different from one another but not multiples of each other, which method comprises the step of printing each of the image parts at its own repeat length repeatedly on the material.

In yet another aspect of the present invention there is provided a printing apparatus comprising transfer means to transfer at least one image from an image carrying element to a material to be printed and feeder means to interpose randomly one or more masking elements between the image carrying element and the material to be printed, whereby the portion of the image masked by the masking element is not transferred to the material.

In a further aspect of the present invention there is provided a material printed with an image, the image comprising a basic image transferred to the material and randomly located areas at which the basic image has not been transferred to the material.

In another aspect of the present invention there is provided a method of printing an image on a material comprising the steps of interposing a masking element at random positions along the material between the material to be printed and an image carrying element and transferring those portions of the image carried on the image carrying element which are not masked by the masking elements to the material to produce a random image on the material.

In order that the present invention may be more readily understood, embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic side view of a rotary multi-cylinder printing apparatus in accordance with one embodiment of the present invention; Figure 2 illustrates a portion of a length of paper printed with an example of a pattern produced by the printing apparatus of Figure 1; Figure 3 is a diagrammatic side view of a printing apparatus in accordance with a second embodiment of the present invention; and Figure 4 is a diagrammatic front view of the printing apparatus of Figure 3.

Referring now to Figure 1 which illustrates a schematic version of a gravure printing press embodying the present invention, it can be seen that a supply reel of paper 1 or the like is fed through the printing press 2 and a pattern is printed onto the paper 1 by each of a plurality of rotating printing cylinders A, B, C and D.

The printed paper is transferred to a second reel 3 for storage.

All of the printing cylinders A, B, C and D have different circumferences. In Figure 1, printing cylinder A has the smallest circumference and printing cylinder D has the largest circumference, whilst printing cylinders B and C have different circumferences between those of printing cylinders A and D.

Ink or dye is applied to each of the printing cylinders A, B, C and D in the conventional manner by rotating the printing surface of each printing cylinder A, B, C, D through a respective inking or dyeing reservoir 4A, 4B, 4C, 4D such that the entire surface of the printing cylinder A, B, C, D is covered with ink or dye. As the printing cylinders rotate and the inked surface leaves the inking reservoir 4A, 4B, 4C, 4D doctor blades 5A, 5B, 5C, 5D remove any excess ink or dye from each of the printing cylinders. In alternative embodiments ink may be applied to the cylinders by inking rollers.

The paper 1 provided from the supply reel is sandwiched between the first printing cylinder A and an impression cylinder 6A and is pulled through the nip between the two cylinders by the rotation of the printing cylinder A. The pressure between the impression cylinder 6A and the printing cylinder A causes a pattern engraved or embossed on the printing cylinder A to be printed on the paper 1. The pattern of each of the printing cylinders B, C and D is similarly applied, in turn, to the paper 1 as it passes through each of the respective pairs of printing cylinders B, C and D and their respective impression cylinders 6B, 6C and 6D so that a composite pattern is produced.

A variable drive is provided to rotate each of the printing cylinders A, B, C, D at a matched printing cylinder surface speed so that the paper is drawn through each of the cylinder pairs at the same speed.

Because each of the cylinders A, B, C, D has a different circumference, each cylinder has a different so called repeat length which is equivalent to the respective circumference of each of the printing cylinders A, B, C, D.

Accordingly, a printing cylinder having a circumference of 1500mm will have a repeat length of 1500mm. Similarly, a printing cylinder having a circumference of llOOmm will have a repeat length of 1100mm.

Figure 2 illustrates a schematic example of a length of paper which has been printed by the printing apparatus of Figure 1. For the sake of clarity of explanation, the width of the paper 1 is illustrated as being divided into four equal longitudinal strips lA, 2B, 1C, 1D, each of which has been printed on by a separate one of the printing cylinders A, B, C, D. In practice, each of the printing cylinders A, B, C, D prints a pattern across the entire width or a selected width of the paper 1 as appropriate.

The first strip 1A shows the pattern printed by printing cylinder A which, in the present simple example, consists of a single dot 8A. The dot 8A is repeatedly printed along the strip 1A. The distance between each of the dots 8A is the repeat length RA of printing cylinder A which is equivalent to the circumference of printing cylinder A. Similarly, the repeat length RB of printing cylinder B which prints a pattern comprising single repeating dots 8B, is equivalent to the circumference of printing cylinder B and adjacent dots 8B printed by printing cylinder B are spaced apart by the repeat length RB. Similarly cylinders C and D print repeating spaced apart single dots 8C and 8D.

In this simplified example, printing cylinder A has a circumference of 2 units, printing cylinder B has a circumference of 3 units, printing cylinder C has a circumference of 5 units and printing cylinder D has a circumference of 7 units. Accordingly, the repeat lengths RA, RB, RC, RD for each of the printing cylinders A, B, C, D are respectively 2, 3, 5 and 7 units. The combined repeat length of two printing cylinders A and B, (RAB) is, in this specific example, 6 units which is equivalent to 3RA or 2RB. This means that every 6 units of length along the printed paper 1 the pattern comprising the dots 8A and 8B repeats itself. By providing the third printing cylinder C, the combined repeat length of the three printing cylinders A, B and C, (RABC) is 30 units which is equivalent to 15 repeat lengths RA, 10 repeat lengths RB or 6 repeat lengths RC of printing cylinder C. By providing the fourth printing cylinder D, the overall combined repeat length of the four printing cylinders A, B, C, D is further increased to 210 units which is equivalent to 105 repeat lengths RA, 70 repeat lengths RB, 42 repeat lengths RC and 30 repeat lengths RD. Accordingly, by providing four cylinders of differing circumference repeatedly printing their respective image parts, the repeat length of the overall combined pattern produced by the printing apparatus has been greatly increased from that which would be available from a printing apparatus provided with a conventional single printing cylinder, or with a plurality of cylinders of the same diameter.

In a preferred embodiment of the present invention, the printing press 2 is provided with six printing cylinders each of a different circumference. In one embodiment, the printing cylinders have the following circumferences: 1,500mm, 1,100mm, 1,400mm, 900mm, 1,300mm and 850mm. Accordingly, the combined repeat length for a printing press embodying the present invention having the aforementioned printing cylinder circumferences is 153.153km.

Consequently, by using a printing apparatus as described above a printed element may be produced, the element carrying a composite image made of a plurality of image parts, the image parts each having different repeat lengths, the repeat lengths of the image parts not being multiples of each other. This imparts a very "random" effect to the printed composite image. If each image part is a random or quasi random image - such as a "camouflage" image, the resultant printed image is very "random" and thus difficult to recognise as camouflage.

In a further embodiment of the present invention, a sublimation dye, or dyes, is used as the ink and is subsequently transferred from the paper to a material, fabric or netting. Accordingly, a very long repeat length pattern is applied directly to a material or fabric for camouflage purposes.

Figures 3 and 4 illustrate a method of printing a pattern onto a material by means of transfer sublimation dyes. In a transfer process, a roll of transfer paper, is provided which is pre-printed with sublimation dyes. This is preferably a roll of paper printed by a printing apparatus as described with reference to Figures 1 and 2.

The transfer paper 10 together with the fabric 11 is passed around the exterior of a rotating heated drum 12. A first roller 13, in combination with a second roller 14 biases a continuous belt 15 towards a major part of the outer surface of the drum 12, thus pressing the paper 10 and the fabric 11 towards the exterior of the drum 12. The transfer paper 10 comes into contact with the heated surface of the drum 12. The drum 12 and the belt 15 force the transfer paper 10 and the fabric 11 into contact with one another. At this time, the heated drum 12 vaporises the sublimation dyes on the transfer paper 10 turning the dyes into gas, which gas transfers into the fabric 11 thereby providing the fabric 11 with a mirror image of the pattern on the transfer paper 10. This process is known as a transfer process.

In this embodiment of the present invention, there is provided, in the transfer printing system, a means to introduce further sheets or masking elements between the sheet of transfer paper 10 and the fabric 11 when the transfer paper 10 and the fabric 11 pass between the heated drum 12 and the belt 15 of a transfer printing system. The further sheets may carry an image printed thereon in sublimation dye or the sheets may be plain. Each of the further sheets may be identical, or there may be a plurality of different types of the further sheets, each carrying their own image. Each sheet may carry a random or quasi random "camouflage" image. Each sheet may have a regular square or rectangle shape or may have a random or quasi random shape corresponding to that of a camouflage image. The shape may be the same as the shape of the image printed on the sheet, or may be a different shape.

The means to introduce the sheets comprise a sheet feeder 16 mounted on a trolley 17 which is movable along tracks 18 which extend parallel to the rotational axis of the heated drum 12 and adjacent the heated surface of the drum 12, the sheet feeder 16 being manoeuvrable along the tracks 18 to alter its position relative to the rotational axis of the heated drum 12. The trolley 17 supporting the sheet feeder 16 is moved along the tracks 18 by a servomotor controlled by a computer associated with a random number generator, which thus positions the sheet feeder 16 along the tracks 18 in random positions. The sheet feeder 16 itself is actuated at random intervals and at the control of the computer. Thus the sheet feeder 16 feeds successive sheets to the heated drum 12 and the belt 15 at random intervals and at random positions relative to the axis of the drum 12. The further sheets 19 described above are fed by the sheet feeder 16 at random intervals and at random positions relative to the rotational axis of the heated drum 12 between the transfer paper 10 and the fabric 11. When a sheet 19 of paper is interposed between the transfer paper 10 and the fabric 11, the sublimation dye carried on the transfer paper 10 will not penetrate the sheet 19 and hence the dye from the transfer paper 10 will not impinge on the fabric 11 thereby causing an area equivalent to the surface area of the sheet 19 to be masked, or not printed, on the fabric 11.

However, as mentioned above, the sheets 19 may be printed with patterns formed by sublimation dyes and hence, when a sheet 19 is interposed between the transfer paper 10 and the fabric 11 between the heated drum 12 and the belt 15, the pattern on the interposed sheet 19 is transferred to the fabric 11 in the area adjacent the sheet rather than the pattern on the transfer paper 10. This produces a new feature in the printed pattern which was not present in the pattern on the transfer paper 10. Accordingly, a truly random pattern is transferred to the fabric 11.

In one embodiment of the present invention, the fabric 11 is printed upon both sides and is therefore reversible and can be used as a camouflage fabric in two contrasting landscapes.

It is envisaged that the material may be a fabric, mesh or net and that the material will be produced in wide widths for use in making uniforms, helicopter covers and other military uses.

Claims

CLAIMS:

1. A printing apparatus for printing a composite image, the apparatus comprising a plurality of printing elements, each printing element carrying an image part of the composite image to be printed, each image part having a respective repeat length, wherein the repeat lengths of the image parts are different from one another but not multiples of each other.

2. A printing apparatus according to Claim 1, wherein the printing elements are rotatable print cylinders each having a respective circumference which defines the repeat length of the image part carried thereby.

3. A printing apparatus according to Claim 2, wherein means are provided to drive the print cylinders with matched surface speeds and to pass material past the cylinders to receive the composite image therefrom.

4. A printing apparatus according to any preceding claim, wherein at least one of the print elements is inked with a sublimation dye.

5. A material carrying a composite image, the image comprising a plurality of image parts, wherein each image part has a respective repeat length, the repeat lengths of the image parts being different from one another but not multiples of each other.

6. A material according to Claim 5, wherein the composite image is a camouflage design.

7. A material according to Claim 5 or 6, wherein the material is paper and the composite image is printed on the paper with one or more sublimation dyes.

8. A material according to Claim 5 or 6, wherein the material is a fabric, mesh or net.

9. A material according to Claim 8, wherein the material is printed with a composite image upon both sides to provide a reversible material.

10. A material according to claim 8 or 9, wherein the image has been printed onto the material by being transferred from a substrate, the image initially being on the substrate in sublimation dye.

11. A method of printing a composite image on a material, the composite image comprising a plurality of image parts, each image part having a repeat length, the repeat lengths of the image parts being different from one another but not multiples of each other, which method comprises the step of printing each of the image parts at its own repeat length repeatedly on the material.

12. A printing apparatus comprising transfer means to transfer at least one image from an image carrying element to a material to be printed and feeder means to interpose randomly one or more masking elements between the image carrying element and the material to be printed, whereby the portion of the image masked by the masking element is not transferred to the material.

13. A printing apparatus according to Claim 12, wherein the feeder means comprises a feeder operable to interpose, at random time intervals and/or at random locations, the masking elements between the image carrying element and the material to be printed.

14. A printing apparatus according to Claim 12 or 13, wherein each masking element comprises a sheet of paper printed with an image, which image on the masking element is transferred to the material to be printed in the area masked by the masking element.

15. A printing apparatus according to any one of Claims 12 to 14, wherein the masking elements are sheets formed in a variety of shapes.

16. A printing apparatus according to any one of Claims 12 to 15, wherein the transfer means comprises a rotatable heated drum and a belt biased against the exterior of the drum wherein a web, comprising the image carrying element, and the material to be printed may be received between the belt and the drum simultaneously.

17. A printing apparatus according to any one of Claims 12 to 16, wherein the image carrying element is paper printed with a pattern in one or more sublimation dyes.

18. A printing apparatus according to any one of Claims 12 to 17, wherein the image carrying element comprises a material according to any one of Claims 5 to 7.

19. A material printed with an image, the image comprising a basic image transferred to the material and randomly located areas at which the basic image has not been transferred to the material.

20. A material according to Claim 19, wherein an image carried on a masking element has been transferred to the material at the said random locations where the basic image has not been transferred to the material.

21. A material according to Claim 19 or 20, wherein the image is a camouflage design.

22. A method of printing an image on a material comprising the steps of interposing a masking element at random positions along the material between the material to be printed and an image carrying element and transferring those portions of the image carried on the image carrying element which are not masked by the masking elements to the material to produce a random image on the material.

23. A method according to Claim 22, wherein the image is transferred to the material by bringing the material to be printed and the image carrying element together, and vaporising a sublimation dye which defines the image carried on the image carrying element.

24. A method according to Claim 23, wherein the material to be printed and the image carrying element are brought into transfer contact by means of a rotatable drum and a belt, which drum is heated to vaporise the dye.

25. A printing apparatus substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

26. A material substantially as herein before described with reference to the accompanying drawings.

27. Any novel feature or combination of features disclosed herein.

27. A method of printing substantially as hereinbefore described with reference to the accompanying drawings.

28. Any novel feature or combination of features disclosed herein.

CLAIMS: 1. A camouflage printing apparatus for printing a camouflage composite image, the apparatus comprising a plurality of printing elements, each printing element carrying an image part of the camouflage composite image to be printed, each image part having a respective repeat length, wherein the repeat lengths of the image parts are different from one another but not multiples of each other.

2. A camouflage printing apparatus according to Claim 1, wherein the printing elements are rotatable print cylinders each having a respective circumference which defines the repeat length of the image part carried thereby.

3. A camouflage printing apparatus according to Claim 2, wherein means are provided to drive the print cylinders with matched surface speeds and to pass material past the cylinders to receive the camouflage composite image therefrom.

4. A camouflage printing apparatus according to any preceding claim, wherein at least one of the print elements is inked with a sublimation dye.

5. A material carrying a camouflage composite image, the camouflage composit image comprising a plurality of image parts, wherein each image part has a respective repeat length, the repeat lengths of the image parts being different from one another but not multiples of each other.

6. A material according to Claim 5, wherein the material is paper and the camouflage composite image is printed on the paper with one or more sublimation dyes.

7. A material according to Claim 5, wherein the material is a fabric, mesh or net.

8. A material according to Claim 7, wherein the material is printed with a camouflage composite image upon both sides to provide a reversible material.

9. A material according to claim 7 or 8, wherein the camouflage compsite image has been printed onto the material by being transferred from a substrate, the camouflage compsite image initially being on the substrate in sublimation dye.

10. A method of printing a camouflage composite image on a material, the camouflage composite image comprising a plurality of image parts, each image part having a repeat length, the repeat lengths of the image parts being different from one another but not multiples of each other, which method comprises the step of printing each of the image parts at its own repeat length repeatedly on the material to produce the camouflage composite image.

11. A printing apparatus comprising transfer means to transfer at least one image from an image carrying element tv a material to be printed and feeder means to interpose randomly one or more masking elements between the image carrying element and the material to be printed, whereby the portion of the image masked by the masking element is not transferred to the material.

12. A printing apparatus according to Claim 11, wherein the feeder means comprises a feeder operable to interpose, at random time intervals and/or at random locations, the masking elements between the image carrying element and the material to be printed.

13. A printing apparatus according to Claim 11 or 12, wherein each masking element comprises a sheet of paper printed with an image, which image on the masking element is transferred to the material to be printed in the area masked by the masking element.

14. A printing apparatus according to any one of Claims 11 to 13, wherein the masking elements are sheets formed in a variety of shapes.

15. A printing apparatus according to any one of Claims 11 to 14, wherein the transfer means comprises a rotatable heated drum and a belt biased against the exterior of the drum wherein a web, comprising the image carrying element, and the material to be printed may be received between the belt and the drum simultaneously.

16. A printing apparatus according to any one of Claims 11 to 15, wherein the image carrying element is paper printed with a pattern in one or more sublimation dyes.

17. A printing apparatus according to any one of Claims 11 to 16, wherein the image carrying element comprises a material according to any one of Claims 5 to 7.

18. A material printed with an image, the image comprising a basic image transferred to the material and randomly located areas at which the basic image has not been transferred to the material.

19. A material according to Claim 18, wherein an image carried on a masking element has been transferred to the material at the said random locations where the basic image has not been transferred to the material.

20. A material according to Claim 18 or 19, wherein the image is a camouflage design.

21. A method of printing an image on a material comprising the steps of interposing a masking element at random positions along the material between the material to be printed and an image carrying element and transferring those portions of the image carried on the image carrying element which are not masked by the masking elements to the material to produce a random image on the material.

22. A method according to Claim 21, wherein the image is transferred to the material by bringing the material to be printed and the image carrying element together, and vaporising a sublimation dye which defines the image carried on the image carrying element.

23. A method according to Claim 22, wherein the material to be printed and the image carrying element are brought into transfer contact by means of a rotatable drum and a belt, which drum is heated to vaporise the dye.

24. A printing apparatus substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

25. A material substantially as herein before described with reference to the accompanying drawings.

26. A method of printing substantially as hereinbefore described with reference to the accompanying drawings.