WO1995001874A1

WO1995001874A1 - Improved method of setting printing plates

Info

Publication number: WO1995001874A1
Application number: PCT/AU1994/000376
Authority: WO
Inventors: Zbigniew Szkuta
Original assignee: Amcor Limited
Priority date: 1993-07-07
Filing date: 1994-07-05
Publication date: 1995-01-19

Abstract

This invention provides a setting process for printing including applying to a design a setting template including locating means, forming a printing plate (30) from the templated design, wherein the resulting printing plate (30) has locating means (33) thereon and setting the printing plate (30) by using a setting means (10), such that the locating means (33) on the printing plate (30) co-operate with locating means (33) on the setting means (10) to ensure correct positioning of the printing plate (30) on the setting means (10). Advantageously the present invention can be used to accurately produce a completed printed design with less time and labour requirements than with previous methods. Additionally, the invention also provides apparatus for setting a printing plate including a setting means, the setting means including locating means, and a design template for application to design artwork to form a templated design, wherein the design template has locating means thereon such that when the printing plate formed from the templated design is to be set, the locating means on the printing plate co-operate with the locating means on the setting means to locate the printing plate in the desired location on the setting means.

Description

IMPROVED METHOD OF SETTING PRINTING PLATES FIELD OF THE INVENTION

The present invention relates to an improved method of producing and setting printing plates, wherein the method is particularly useful in multi-coloured designs and printed designs which are created from a number of printing plates. The invention also provides a novel setting system used for the formation of printing plates. The invention provides an improved method and apparatus for producing completed printing plates, also known as printing stereos. BACKGROUND TO THE INVENTION In all printing processes the design to be printed is firstly created, and in most cases, designed in relation to the surface that the design is to be eventually printed upon. For example, when a design is to be applied to a cardboard box, the design is developed in relation to the physical configuration and limitations of the box blank. In recent times computer-aided design has been employed in the creation of the design work wherein the constraints of the material to which the design is to be applied can be pre-programmed or stored in the design software. Thus, the designer automatically designs the artwork within the constraints of the medium upon which the design is to be applied.

Once the design is completed, the design is then prepared for the manufacture of the printing plates. Preparation of art for plate manufacture falls basically into two groups: that is, the decompressed method and the compressed method.

The decompressed method of forming a printing plate requires the design to be developed, initially, in the manner in which it is exactly going to appear upon the printing surface. That is, the relationship of the designs, if there are more than one, relative to each other and also relative to the physical constraints of the printing surface, that is, for example in relation to the edges of the printing surface. It is from this actual design layout that the plate is formed. The plate generally has the same shape as the printing surface so that alignment of the plate to the printing surface can easily be made. In the decompressed method, whilst alignment of the printing plate upon the printing surface and thus similarly, multi-coloured designs can with reasonable accuracy be printed using the decompressed method, there is considerable wastage of plate material. In the case where resins are used to make the printing plate, it has been found that more than 50% of the plate is in fact non-printing surface which is just thrown away. This wastage significantly increases the cost in producing the printing plate and furthermore, due to the larger surface area of resin used, there are higher costs in processing and producing the printing plate. The other problem with producing decompressed printing plates is that for regularly used designs, the storing of large negatives and printing plates is more costly when considering space requirements and furthermore, due to the size of the negatives, they become easily damaged often resulting in them needing to be re-made.

The compressed method of plate manufacture as the name suggests compresses a number of design components so that they are moved as close as possible to each other, leaving minimal space between each of the design components. Thus, the total area becomes compressed by reducing non¬ printing distances between all plates. Advantageously, this method significantly minimises wastage of the plate-forming material resulting in more plates produced per quantity of raw material or resin. Generally, negatives and printing plates produced by the compressed method are smaller in size minimising the likelihood of damage to the negatives and plates and reducing the storage space required to store the designs which are frequently used. Furthermore, if minor changes or repairs are required to the negative or printing plates, as is the case in the decompressed method, the entire design printing plates need not be re-made and only the parts where necessary need to be changed. However, despite the advantages of the compressed method, when it comes to producing more difficult designs such as, multi-coloured designs in a repetitive manner (for example, two or more boxes are printed at the same time or consecutively in the one print cycle) the accuracy of setting the printing plates is critical and the setting of the numerous components for the print plate can be, in order to ensure that the desired accuracy is achieved, a time consuming and labour intensive process. In order to produce multi-colour designs, separate printing plates must be formulated for each colour, thus in many cases resulting in a significant number of designs to be set into printing position.

Generally, the "glass top" principle is used to set the printing plates made from the compressed method. The first printing plate is produced in the conventional way and is to a certain degree a hit and miss process. Initially, a backing sheet is laid flat and through measurement and adjustment the individual plates are located onto the backing sheet. Once in the correct location the individual plates are fixed to the backing sheet. Then this first completed printing plate or stereo, as they are sometimes called, is inked and placed, if not already in place, onto a setting table and underneath a hinge transparent plastic or glass sheet. The hinged transparent sheet is lowered and a print impression is produced on the transparent sheet.

The transparent sheet is lifted and the printed stereo or plate is removed. A new backing sheet is placed onto the setting table and the design components of the next colour are manoeuvred until the print plates match precisely with the ink impression on the transparent sheet once the sheet has been lowered. The individual plates are affixed to the bonding sheet and a print of the new stereo is added to the transparent sheet and colour registration is assessed. All additional colours are set in a similar manner. As is apparent, the prior art setting process which is also utilised for setting printing plates made from the decompression method, is extremely labour intensive and time consuming. This is particularly true when the compressed method is used to form the printing plate, since each design component has to be individually registered. Whilst, more often than not the glass top method is reasonably accurate, it is nonetheless subject to errors and more so when the printing plates are quite large. With large plates the colour register between two or more colours is generally not as precise as for smaller plates and this results from the parallax error in setting the plates relative to each other. Another problem with this setting procedure is if there are any changes made to the design or the plates needs repairing, the entire setting procedure must be repeated to ensure correct alignment of the newly made plate or repaired plate with the other existing plates.

Thus, the present invention aims to address some of the problems associated with the apparatus and processes of setting printing plates of the prior art.

SUMMARY OF THE INVENTION

Thus, the present invention provides a setting process for printing, said process including applying to a design a setting template including locating means, forming a printing plate from the templated design, wherein the resulting printing plate has locating means thereon, and setting the printing plate by using a setting means, such that the locating means on the printing plate co-operates with locating means on the setting means to ensure correct positioning of the printing plate on the setting means.

This invention is predicated upon the discovery that the use of a setting template which is applied to a design to form a templated design from which a printing plate is formed and which has locating means thereon, and the use of co-operating locating means on a setting means on which the plate is set results in a significant reduction in the time, labour and material requirements to accurately produce a completed printed design, particularly in the case where the printing plates are created by the compressed method of plate manufacture.

Advantageously the present invention can be used to accurately produce a completed printed design with less time and labour requirements than with previous methods.

Preferably, the setting process is used for multi-coloured designs, however, is equally useful in setting printing plates which are used in single coloured designs and similarly single cycle designs. Furthermore, the setting process is particularly suitable for printing plates produced by the compressed method.

In respect of the setting template which is applied to the design, this is preferably initiated by the actual designer when drafting the design. If, for example, the design is developed using a computer, the setting template can be stored by the computer, such as by being pre-programmed into the design software, so that upon command the setting template can be incorporated in the design work to form a templated design.

The locating means on the printing plate and the setting means are preferably a co-operating system wherein mechanical means are located on the actual printing surface of the plate and these correspondingly cooperate with locating means on the setting table. In one form the locating means on the printing plate are integral in the printing plate. For example, lugs can be produced on the face of the design/plate, wherein the setting table has corresponding holes to accommodate the lugs produced on the design/plate face. Alternatively the locating means of the printing plate may be separate to the printing plate and may be attached to the printing plate after it has been created. The locating means can be similarly coded using numbers or letters or similarly, using corresponding shapes. Thus, for example, a lug coded 1 will co¬ operate with a locating means on the setting table such as a correspondingly shaped hole or recess also coded 1. It is envisaged that any suitable coding system can be used.

Preferably in one form of the present invention the setting process also includes using a setting means to which is applied a similar setting template as is applied to the design, such that the locating means on the printing plate corresponds to similar and corresponding locating means on the setting means to ensure correct positioning of the printing plate on the setting means.

Additionally, the invention also provides a setting system including a design template for application to the artwork which can be and is preferably electronically stored, such as by means of a computer. In one form of the invention the setting system also preferably includes a setting template which is located on a setting means, wherein the setting template includes locating means such that when the printing plate is to be set the locating means on the actual printing plate formed from the artwork with the design template thereon cooperate with the locating means of the setting template. The invention also provides apparatus for setting a printing plate, said apparatus including a setting means, said setting means including locating means, and a design template for application to design artwork to form a templated design, wherein the design template has locating means thereon such that when the printing plate formed from the templated design is to be set, the locating means on the printing plate co-operates with the locating means on the setting means to locate the printing plate in the desired location on the setting means.

In one form of the invention the apparatus also preferably includes a setting means to which is applied a setting template which corresponds to the setting template applied to design, wherein each of said setting templates applied to the design and the setting means have locating means thereon such that when the printing plate formed from the templated design is to be set, the locating means on the printing plate co-operates with the locating means of the setting template to locate the printing plate in the desired location on the setting means.

In an alternative form of the invention the apparatus preferably includes locating means which can be positioned on the setting means, wherein the locating means are capable of being held in the desired location on the setting means by means of a magnetic field and which are adapted to co-operate with the locating means on the printing plate to locate the printing plate in the desired location on the setting means. The present invention also provides a design package including an electronically stored design template for use in the process of the present invention and additionally, a setting apparatus to be used for the same. Preferably the design template is stored by computer and is applied to the design artwork at the time the design is being created on the computer to form the templated design.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood and appreciated with reference to the accompanying drawings which illustrate the preferred embodiment of the invention: Figure 1 illustrates a setting means in accordance with one embodiment of the present invention, with a setting template applied thereto. Figure 2 illustrates artwork as applied to the article to be printed with the setting template applied thereto.

Figure 3 illustrates how the printing plate, with its design work and locating means, cooperates with one embodiment of the setting means. Figure 4 illustrates the arrangement depicted in Figure 3 with the printing plate in situ on the setting means.

Figure 5 illustrates how the printing plate, with its design work and locating means, cooperates with an alternative embodiment of the setting means. Figure 6 illustrates the arrangement depicted in Figure 5 with the printing plate in situ on the setting means.

Figure 7 depicts a locating means integrally formed in a portion of a printing plate and the corresponding cooperating locating means of the setting means as depicted in Figure 5. Figure 8 illustrates a preferred embodiment of the locating means according to the arrangement depicted in Figure 1 as applied to both the printing plate and the setting means.

Figure 9 illustrates how the backing is applied to the correctly aligned printing plates to form a printing stereo. DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will be better understood and appreciated from the following description of the preferred embodiment of the invention with reference to the accompanying drawings.

Figure 1 illustrates a setting means 10 according to one embodiment of the present invention with a setting template applied thereto, that is, items 11 , 12 and 13. In this embodiment the setting means 10 preferably includes a setting table to which the setting template is applied and upon which the printing plate or plates are positioned. Centre line 11 and grip edge (line) 12 assist in ensuring that the design will be correctly aligned relative to the surface to be printed upon, but also when the completed printing plate or stereo is to be fitted into the printing machine, the relationship between the design and the grip edge of the stereo which fits into the printing machine is automatically and consistently controlled. Previously, it was sometimes very difficult to align the printing plate or stereo so that the print would print upon the article in the correct position. This resulted, in the case of cardboard box blanks, board wastage when the print was first installed into the machine or in the machine set-up stage. Referring to Figure 2 the design 22, is created as per normal and it has become a more recent development that designers have made use of computers to assist in the design step. Figure 2 illustrates a design 22 as it is applied to the printing surface 21 , in this case, a cardboard box blank. The limitations of the cardboard box blank can be pre-programmed into the design program as can the centre line 11 and grip edge 12. Once the design 22 is complete, the designer lays out his design 22 in relation to the physical limitations of the surface 21 and the centre line 11 and grip edge 12. The remainder of the setting template, locating means, 13, can then be applied to the completed design layout (items 21 and 22). The locating means 13 as illustrated are circular in nature, however, it is envisaged that the locating means can be of any shape and are preferably coded either by number or any other coding system such that the locating means on the printing plate can be matched up with the locating means on the setting means.

In the preferred embodiment of the present invention, at least two locating means 13 are chosen for each individual printing plate. In multi-coloured designs, separate plates are formed for each colour and where multi-colours overlap or cooperate with each other, the same locating means 13 are chosen for each plate. Thus, each design component 22 will have at least on its design, but generally not overlapping with the design, at least two locating means 13 superimposed thereon. The designs 22 with locating means 13 are optionally "compressed", which can be easily done using the computer to rearrange the design components; however, the setting arrangement of the present invention is also suitable for use in the decompressed method. It is noted that the design process and the application of the template is preferably performed by the designer during the design phase and if the design step is assisted by computer aided design, then the setting template can easily be applied to the design work electronically. Advantageously, by having the designer have total control over the design process and also the selection and application of the setting template, the artwork including the relative positioning thereof is reproduced more accurately and the final product will resemble the original design more closely. Previously, with prior art setting methods, the final product, due to the trial and error method of setting the printing plates and also to some extent due to the experience or lack of experience of the setter, the final printed product could vary significantly from the design as originally created by the designer.

Once the designs 22 have been completed and templated the printing plate, or printing plates, can be made using conventional methods. In one method of producing printing plates, negatives of the design are made and the printing plates can be formed from the negative using a photo-sensitive synthetic resin / rubber.

If the printing plate 30 has been formed using the compressed method, the individual plates 30 are formed by cutting and preferably at the same time a suitable adhesive (not shown), such as a double sided tape, is applied to the rear of the plate 30. The printing plate 30 with the locating means 33 is now ready for setting.

With reference to Figure 8, in the preferred embodiment depicted the locating means 13 on the setting means 10 and the locating means 33 on the printing plate 30 are correspondingly coded and in this case the locating means 13 and 33 are respectively numbered. As indicated previously, it is envisaged that the locating means can be any form including corresponding shapes, letters, providing the locating means on the plate 30 can be matched up and preferably cooperate with the locating means of the setting means. The locating means 13 on the setting means 10 preferably includes a locating element which can be positioned on the setting means at the desired location and which is adapted to cooperate with the locating means 33 of the printing plate so as to ensure that the printing plate is correctly located on the setting means. In one form the locating element takes the form of a plug means 14 which is adapted to engage with the setting means and which is also adapted to engage with the locating means 33 of the printing plate 30. The plug means can be placed at the desired coded locations on the setting means and receive the corresponding locating means 33 of the printing plate 30. In one possible form of the invention the locating means 13 on the setting table includes of a grid of coded recesses or holes into which the plug means can be fitted. Thus, the corresponding locating means 33 of the printing plate is matched up with the locating means 13 and optional plug means 14, such that the plate 30 is correctly located and is temporarily retained in the correct position.

Figures 3 and 4 illustrate in more detail a particularly preferred arrangement for the locating means 33 on the printing plate 30 and the locating means 13 on setting means 10. As can be seen from Figures 3 and 4, the locating means 33 are preferably lugs and the locating means 13 can additionally have optional locating elements in the form of plugs 14 which fit into the "to be used" locating means 13 and are accordingly shaped so as to accommodate the locating means 33 snugly. The optional plugs 14 assist in temporarily retaining, without slippage, the plate 30 in the correct position.

In an alternative arrangement of the present invention, the locating means on the setting means includes locating elements 14 which are placed on the setting means at the desired locations. The locating elements are manufactured from a material, such as iron, such that they are capable of being either temporarily or permanently magnetised. Preferably the setting means includes a setting table upon which the locating elements are positioned. In one arrangement the setting means also includes a means for providing a magnetic field which can be employed to magnetically attract the locating elements to the surface of the setting table and hence temporarily fix the position of the locating elements in the desired positions on the setting table. Alternatively the locating elements may provide the magnetic field, such as by being in the form of permanent magnets which are attracted to the surface of the setting table which is made from a suitable material, such as an alloy of iron. Preferably the locating elements are flat, disc elements which are adapted to receive the locating means 33 of the printing plate. Figures 5 and 6 illustrate this arrangement in more detail. The locating elements 14 are positioned on the setting table of the setting means 10 in the desired locations and a magnetic field is employed to ensure that no movement of the locating elements occurs. In one possible arrangement the locating elements 14 are placed in the desired locations on the setting means 10 by a controlled positioning means, such as a robotic arm. The coordinates for controlling the positioning means and hence correctly positioning the locating elements on the setting table may be derived from the template information contained on the computer when the designer creates the templated design. This arrangement alleviates the need for a grid of locating means on the setting table or the need for a grid of coded recesses on the setting table. Referring to Figure 7 it is preferable that the locating means 33 of the printing plate is integrally formed in the printing plate. The locating means 33 of the plate is sized and shaped to cooperate with the corresponding locating means of the setting means. Figure 7 depicts a locating element 14 as used in the arrangement depicted in Figures 5 and 6. The locating element 14 preferably takes the form of a flat disc member which contains an inner recess for receiving the corresponding locating means 33 of the printing plate.

It should be noted that although the accompanying representations depict male locating means 33 on the printing plate 30 which engage with corresponding female locating means 13 or 14 on the setting means, this is not critical to the invention. It should be understood that the inverse arrangement is possible: that is, for the printing plate to have female locating means and for there to be male locating means on the setting means. Also other locating arrangements are possible so long as the printing plate is retained in the desired position when placed on the setting means. Once the relevant individual plates 30 have been set into the correct position on the setting means, a backing sheet 40 can then be applied and adhered to the rear of the individual printing plates 30 to form a printing stereo and reference is made to Figure 9 which illustrates this process. Once the locating means 33 are removed from the stereo, the stereo is ready for printing. Generally, this stereo is fitted directly onto the printing roll (not shown) for printing. If a multi-colour design is being produced, then the other stereos for each colour are prepared in a similar manner. Thus, the present invention provides a method and apparatus which greatly increases the speed of setting printing plates ready for printing and similarly, significantly reducing labour costs involved in preparing printing plates. Additionally, even with the relatively high speed of setting, the invention provides accurate colour registration between multi-colours, at a reasonable cost since the costs of installing the setting apparatus of the present invention are low. Furthermore, the quality of colour registration and setting does not depend upon the experience or skill of the setter. The present invention enables the setting of multi-coloured jobs to be as simple as singled coloured jobs. Unlike with old conventional setting systems, multi-coloured jobs do not take up to three or four times the time to set a single colour job. Additionally, the setting system of the present invention is not dependent upon the plate height used and various plate heights can be used in the present system and process. Particularly advantageously, because of the setting process being so quick, this allows effective use of the compression technique and of course all of the advantages of the compression technique are also observed when using the present invention. That is, the compression technique reduces the costs of raw materials, enables more plates per cycle to be produced, requires less storage space to store the regularly used and completed printing plates. Furthermore, because with the compression method, the negatives are generally smaller, they are less likely to be damaged. Finally, with the present system when used in combination with the compression technique, if one of the multi-coloured stereos has to be repaired, it does not require that the whole system be re-registered as was the case with conventional setting systems and in particular the glass top method.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A setting process for printing, said process including applying to a design a setting template including locating means, forming a printing plate from the templated design, wherein the resulting printing plate has locating means thereon, and setting the printing plate by using a setting means, such that the locating means on the printing plate co-operates with locating means on the setting means to ensure correct positioning of the printing plate on the setting means.

2. The setting process as defined in Claim 1 wherein said process is used to produce a printed design which is created from a plurality of printing plates.

3. The setting process as defined in either Claim 1 to 2 wherein said printing plates are produced by a compressed method of plate manufacture.

4. The setting process as defined in any one of Claims 1 to 3 wherein said process is used to produce a multicoloured design.

5. The setting process as defined in any one of Claims 1 to 4 wherein the setting template for the design is applied to the design at the time the design is being drafted so as to form the templated design.

6. The setting process as defined in Claim 5 wherein the design is drafted using a computer and the setting template stored by the computer and is incorporated into the design at the time the design is being drafted to form the templated design.

7. The setting process as defined in Claim 6 wherein the setting template is pre-programmed into design software such that during drafting of the design on the computer the setting template is incorporated in the design to form the templated design.

8. The setting process as defined in any one of Claims 1 to 7 wherein in forming said printed plate from the said templated design the locating means on the printing plate is/are integrally formed on said printing plate.

9. The setting process as defined in any one of Claims 1 to 8 wherein said process includes using the setting means with a corresponding setting template as applied to the design applied thereto, such that the locating means on the printing plate correspond to co-operating locating means on the setting means to ensure correct positioning of the printing plate on the setting means.

10. The setting process as defined in any one of Claims 1 to 9 wherein after said printing plate or printing plates are positioned on said setting means a backing sheet is adhered to said printing plate or printing plates to form a printing stereo.

11. Apparatus for setting a printing plate, said apparatus including a setting means, said setting means including locating means, and a design template for application to design artwork to form a templated design, wherein the design template has locating means thereon such that when the printing plate formed from the templated design is to be set, the locating means on the printing plate co-operates with the locating means on the setting means to locate the printing plate in the desired location on the setting means.

12. The setting apparatus as defined in Claim 10 wherein said setting means includes a setting template corresponding to said design template so as to enable the said printing plate to be positioned in the desired location on the setting means.

13. The setting apparatus as defined in either Claim 11 or 12 wherein said locating means on the printing plate is integral with the printing plate.

14. The setting apparatus as defined in any one of claims 11 to 13 wherein said locating means on said setting means includes locating elements which are adapted to cooperate with said locating means on said printing plate and which are positioned on said setting means at the desired location to receive said locating means of said printing plate.

15. The setting apparatus as defined in Claim 14 wherein said locating elements are adapted to engage with said setting means.

16. The setting apparatus as defined in Claim 14 wherein said locating elements are held in position on said setting means by means of a magnetic field.