GB2360743A

GB2360743A - Apparatus for applying a simulated engraved image to a substrate using a combined offset lithography and embossing system

Info

Publication number: GB2360743A
Application number: GB0107794A
Authority: GB
Inventors: James W Richardson
Original assignee: Hallmark Cards Inc
Current assignee: Hallmark Cards Inc
Priority date: 2000-03-31
Filing date: 2001-03-28
Publication date: 2001-10-03
Also published as: GB0107794D0

Abstract

Apparatus for applying a simulated engraved image to a substrate (17) simultaneously prints an ink image on one side of the substrate and embosses the image on the other side of the substrate in registration with the printed image using a combined offset lithography and embossing system (13). A print cylinder (19) has a lithographic plate with the image to be printed thereon. A blanket cylinder (21) is positioned in rotating contact with the plate cylinder to receive an ink image from the plate cylinder. An emboss cylinder (23), which includes an emboss plate (29) having the image positioned in registration with the image on the blanket cylinder, is positioned in rotating contact with the blanket cylinder. As the blanket cylinder and emboss cylinder are rotated with the substrate therebetween, the blanket cylinder applies the ink image to one side of the substrate while the emboss cylinder simultaneously embosses the image into the other side of the substrate in registration with the printed image. The use of a thermography machine (15) which applies a thermographic coating to the printed image and enhances the raised image effect.

Description

2360743 EMBOSSED PRINTING PROCESS AND SYSTEM The present invention relates

generally to the field of printing, and more particularly to a process of and system for combining embossing with offset printing and thermography to achieve a simulated engraved or intaglio effect.

Engraving is printing process that is used for printing articles such as fine quality invitations, letterheads, business or calling cards, and the like.

The engraving process uses intaglio, or recessed engraving plates, typically made of steel or copper.

Engraving plates are engraved with the letters or images to be printed to form recessed wells in the surface of the plate. Ink sits in the wells of the plate while the printing press exerts force on the paper or other media.

The press forces the paper into the wells and onto the ink. The pressure exerted creates raised letters and images on the front of the sheet and indentations on the -back.

People associate the raised lettering effect produced by engraving with quality and attention to detail. Many businesses and individuals wish to convey the image that is associated with engraved paper articles. However, engraving is typically substantially more expensive and time-consuming than other printing processes, such as offset lithography.

Offset lithography is a printing process based upon the principle that oil and water do not mix. The surface 2 of a lithographic plate normally attracts water and repels ink. The image to be printed is applied to a plate by making image bearing portions of the plate attract oily ink and repel water. The plate is affixed to a plate cylinder. Inking and dampening systems are provided for applying a mixture of ink and water to the plate. The ink is attracted to the image bearing parts of the plate and the water is attracted to remaining surface of the plate. The ink image is transferred from the plate cylinder to a blanket cylinder. The blanket cylinder is mounted to rotate with an impression cylinder. The paper is passed between the blanket cylinder and the impression cylinder to receive the ink image.

While offset lithography -produces good quality printing at reasonable cost, the lettering and images produced by offset lithography are flat and not raised.

Accordingly, offset lithography is not used for printing quality articles. The raised lettering effect of engraving can be simulated using a less costly process known as thermography. In thermography, the image is applied to the paper using a conventional printing process, such as offset lithography. After printing the image, and while the ink is still tacky, the paper is dusted with a resin powder that sticks to the tacky ink.

The powder is then vacuum-removed so that it remains only on the inked areas of the paper. Then the paper is heated to cause the powder to melt and fuse to the ink.

Finally, the paper is cooled to finish the process.

Thermography is currently used as a relatively inexpensive substitute for the more expensive and time consuming engraving process to produce letterheads, envelopes, business cards, wedding invitations or announcements, and the like. While thermography produces the desired raised image effect similar to that produced by engraving, thermographically produced articles lack the indented backside image characteristic of articles produced by the engraving process. Accordingly, discriminating observers can tell the difference between articles produced by engraving and those produced by thermography.

It is therefore an object of the present invention to provide a relatively inexpensive printing method that simulates more closely engraving than the currently existing thermography process.

is According to the present invention in one aspect there is provided a method of and apparatus for applying an image to a substrate by printing an ink image on one side of the substrate and embossing the image on the other side of the substrate in registration with the printed image. The method of the present invention may include the step of applying a thermographic coating to the ink image to enhance the raised image effect.

In accordance with the invention in another aspect, there may be provided a printing system, which comprises a print cylinder, said print cylinder including a plate for bearing an image thereon; a blanket cylinder positioned in rotating contact with said plate cylinder to receive said image from said plate cylinder; and, an emboss cylinder positioned in rotating contact with said blanket cylinder, said emboss cylinder including an emboss plate for bearing the same image positioned in registration with said image on said blanket cylinder, whereby a substrate passed between said blanket cylinder and said emboss cylinder in 3 5 operation is simultaneously printed with said image on a first side and embossed with said image on a second side.

In accordance with the invention in a further aspect, there may be provided a method of applying a simulated engraved image to a substrate, which comprises the steps of applying a first ink image to a blanket cylinder; transferring said first ink image to an emboss cylinder; forming an emboss plate with said image thereon; registering said image of said emboss plate with said first ink image on said emboss cylinder.

In accordance with the invention in a yet further aspect, there may be provided a method of printing a simulated engraved image, which comprise the steps of preparing a negative of an image; preparing a lithographic printing plate from said negative; preparing an emboss plate from said negative; affixing said lithographic printing plate to a print cylinder; affixing said emboss plate to an emboss cylinder; transferring ink from said lithographic printing plate to a blanket cylinder in registration with said emboss plate; rotating said emboss cylinder and said blanket cylinder with media to be printed therebetween, thereby to print said image on one side of said media and emboss said image on the other side of said medi-a.

The method of the present invention is preferably implemented in a combined offset lithography and embossing system. The system may include a print cylinder having a lithographic plate with the image to be printed thereon. A blanket cylinder may be positioned in rotating contact with the plate cylinder to receive an ink image from the plate cylinder. An emboss cylinder may be positioned in rotating contact with said blanket cylinder. The emboss cylinder may include an emboss plate having the image positioned in registration with the image on said blanket cylinder. As the blanket cylinder and emboss cylinder are rotated with the media therebetween, the blanket cylinder applies the ink image to one side of the media while the blanket cylinder and emboss cylinder cooperate to simultaneously emboss the image into the other side of the media, in registration with the printed image. The system preferably includes a thermography machine for applying a thermographic coating to the printed image to enhance the raised image effect.

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

Figure 1 is a semi-pictorial illustration of an apparatus embodying the present invention; is Figure 2 is a view of offset printing and embossing components used in a process embodying the present invention; and Figure 3 is a f low diagram of a process embodying the present invention.

Referring now to the drawings, an apparatus (also referred to as a system) embodying the present invention is designated generally by the numeral 11. System 11 includes a combined offset lithography and embossing system, designated generally by the numeral 13, and a thermography machine 15. System 11 is adapted, according to the present embodiment, to apply an image to a substrate 17 advanced through combined offset lithography system 13 and thermography machine 15. For the purposes of this disclosure, the term image is used in its broad sense to include alpha-numeric characters, lines, pictures, drawings, and any other indicia that may be printed on a substrate. Substrate 17 is preferably paper or card stock, which may be processed according to the present invention as sheets or a continuous web.

The combinedoffset lithography and embossing system includes a plate cylinder 19, a blanket cylinder 21, and an emboss cylinder 23. Cylinders 19-23 are each of substantially the same diameter and they are mounted for rotation with respect to each other as shown by arrows in Figure 1. Plate cylinder 19 carries a conventional lithographic plate (not shown) The lithographic plate is prepared in the manner well known to those skilled in the art from a negative of the image to be printed. Ink and water are applied to plate cylinder 19 by a system of inking rollers 25 and dampening rollers 27, respectively.

As is well known to those skilled in the art, the image bearing portions of the lithographic plate attract ink and repel water, while the nonimage -bearing portions of the lithographic plate attract water and repel ink.

Thus, as plate cylinder 19 is rotated past roller systems and 27, the image-bearing portions of the lithographic plate become covered with ink and the non- image -bearing portions of the lithographic plate become covered with water.

According to conventional offset lithography, the inked image is transferred from plate cylinder 19 to blanket cylinder 21. The surface of blanket cylinder 21 is made of a flexible rubber-like material. In conventional offset lithography, an impression cylinder is mounted for rotation with blanket cylinder. The inked image is transferred from the blanket cylinder to the substrate as the substrate moves between the blanket cylinder and the impression cylinder. The combined offset lithography and embossing system of the present embodiment of the 7 invention includes the emboss cylinder 23 in place of the impression cylinder of the prior art.

As best shown in Figure 2, the emboss cylinder 23 carries an emboss plate or die 29. In the preferred embodiment, emboss plate 29 is made of relatively hard, preferably transparent, acid-etchable, plastic material, such as dacryl. Emboss plate 29 is prepared according to the present embodiment to include a raised image, indicated in Figure 2 by raised portions 31.

The raised image of emboss plate 29 is formed from the same negative used to form the image on the lithographic plate of plate cylinder 13. A photo-resist is applied to the surface of a sheet of the acid-etchable material. Then the surface is exposed to light through the negative. The unexposed portions of the photo-resist material are then washed or otherwise removed and the surface is exposed to an acid to etch away the non-image bearing surface of emboss plate 29.

Emboss plate 29 is positioned on emboss cylinder 23 in registration with the ink image on blanket cylinder 21. Preferably, during setup before actual production and before emboss plate 29 affixed to emboss cylinder 23, a white, or otherwise clearly visible, ink image is applied to the surface of emboss cylinder 23 by operating combined offset lithography and embossing system 13 without paper and emboss plate 29. After the white ink image is applied to emboss cylinder 23, the system is stopped and an operator affixes emboss plate 29 to emboss cylinder 23 in registration with the white ink image.

Then the system is operated to clean, or otherwise remove the white ink from the inking rollers 25, plate cylinder 19, and blanket cylinder 21.

In operation of combined offset lithography and embossing system 13, blanket cylinder 21 and emboss cylinder 23 are rotated with substrate 17 passing therebetween. Blanket cylinder 21 applies an ink image 33 to the front of substrate 17 while emboss plate 29 embosses the image 35 from the back of substrate 17.

After passing between blanket cylinder 21 and emboss cylinder 23, substrate 17 bears a raised ink image on its 4= front side and a substantially identical indented mirror image on its back side. Thus, the product produced by combined offset lithography and embossing system 13 closely resembles a product produced by the more expensive engraving process.

The raised image effect may be enhanced accordinq to preferred embodiments of the present invention by the application of a thermographic process after substrate 17 has been processed by combined offset lithography and embossing system 13. Referring again to Figure 1, while the ink applied to substrate 15 is still tacky, substrate 17 is conveyed to thermography machine 15. Thermography machine 15 is conventional and, as well known to those skilled in the art, it includes a powder source, a vacuum station, and a heating station. The powder source applies a thermographic powder to the upper surface of substrate 17. The thermographic powder may be clear, matt, colored, pearlescent, or metallic. Preferably, a metallic thermographic powder comprises a mixture of metal and plastic particles. When a metallic powder is used, it is preferable to use a compatible color ink in combined offset lithography and embossing system 13 to enhance the color of the product.

After applying the powder, thermography machine 15 conveys substrate 17 to the vacuum station where the powder is removed from the uninked portions of substrate 17. Then, substrate 17 is conveyed to the heating station where the substrate is heated to melt and fuse the powder. After heating, substrate is cooled.

The overall process of the embodiments described may be summarized with reference to Figure 3. A photographic negative of the image to be applied is prepared at step 41. Then, the negative is used to prepare the lithographic print plate in the conventional manner, as indicated at step 43. Then, as generally indicated at step 45, the emboss plate is prepared. The emboss plate preparation step includes applying a photo-resist to the surface of a relatively hard, flexible, acid-etchable, preferably transparent, plastic material, such as dacryl.

The material of the emboss plate is selected to have substantial hardness to emboss the substrate. The nhoto resist is exposed through the same negative used in the preparation of the print plate. The photo-resist is then removed from the unexposed, non- image -bearing, surface of the emboss plate. The surface is then acid etched to form a raised image.

During setup, the emboss plate is registered on emboss cylinder 23 by first fixing the print plate on print cylinder 19, as indicated at step 47. Then, system 13 is operated with a preferably white ink to apply the image to emboss cylinder 23, as indicated at step 49.

Then, the emboss plate is affixed with the raised image registered with the printed image on the emboss cylinder 23, as indicated at step 51. Since the emboss plate is substantially transparent, the setup operator can see through the emboss plate to align the raised image on the emboss plate with the white ink image on the emboss cylinder. After cleaning the white ink from the system, the combined offset lithographic and embossing system is operated to print the image on the f ront side of the media and emboss the image on the back side of the media, as indicated at step 53. Preferably, a thermographic powder is applied to the front side of the media, at step 55. The excess powder is vacuum removed from the media, at step 57. The media is then heated to fuse the powder, at step 59.

The media is then cooled, at step 61, to complete the process.

From the foregoing, it may be seen that described embodiments of the present invention provides a relatively low cost, high volume, method and system for producing simulated engraved printed articles. A presently preferred embodiment of the present invention has been illustrated and described. Those skilled in the art will recognise alternative embodiments, given the benefit of this disclosure. Accordingly, the foregoing is intended for purposes of illustration rather than limitation.

Claims

1. A method of applying a simulated engraved image to a substrate, which comprises the steps of:

printing an ink image on a first side of said substrate; and, simultaneously embossing said image on a second side of said substrate in registration with said printed image.

2. A method as claimed in claim 1, wherein said step of printing said image on said f irst side of said substrate includes the steps of:

applying an ink image to a blanket cylinder.

3. A method as claimed in claim 2, wherein said step of simultaneously embossing said image includes the steps of:

preparing an emboss plate bearing said image; and, affixing said emboss plate to an emboss cylinder in registration with said ink image on said blanket cylinder.

4. A method as claimed in claim 3, wherein said step of preparing said emboss plate includes the step of:

acid etching a raised image on the surface of a flexible sheet.

5. A method as claimed in Claim 4, wherein said step of affixing said emboss plate on said emboss cylinder includes the steps of:

applying a visible image to said emboss cylinder; registering said raised image with said visible image; and, affixing said emboss plate to said emboss cylinder.

6. A method as claimed in any preceding claim, including the step of applying a thermographic coating to said ink image.

is

7. A printing system, which comprises:

a print cylinder, said print cylinder including a plate for bearing an image thereon; a blanket cylinder positioned in rotating contact with said plate cylinder to receive said image from said plate cylinder; and, an emboss cylinder positioned in rotating contact with said blanket cylinder, said emboss cylinder including an emboss plate for bearing the same image positioned in registration with said image on said blanket cylinder, whereby a substrate passed between said blanket cylinder and said emboss cylinder in operation is simultaneously printed with said image on a first side and embossed with said image on a second side.

8. A printing system as claimed in Claim 7, wherein said emboss plate is formed from an acid-etchable, substantially transparent material.

9 A printing system as claimed in Claim 7 or 8, including a thermography machine positioned to receive said substrate with said image printed thereon and apply a thermographic coating to said printed image.

10. A method of applying a simulated engraved image to a substrate, which comprises the steps of:

applying a first ink image to a blanket cylinder; transferring said first ink image to an emboss cylinder; forming an emboss plate with said image thereon; is registering said image of said emboss plate with said first ink image on said emboss cylinder.

11. A method as claimed in Claim 1-0, including the step of:

positioning said emboss cylinder in rotating contact with said blanket cylinder.

12. A method as claimed in Claim 11, including the steps of:

applying a second ink image to said blanket cylinder with said emboss cylinder in rotating contact therewith; and, passing said substrate between said blanket cylinder and said emboss cylinder, thereby applying said second ink image to a first side of said substrate and embossing said image on a second side of said substrate in registration with said second ink image.

13. A method as claimed in Claim 12, including the steps of:

applying a thermographic powder to said second ink image on said f irst side of said substrate; and, fusing said thermographic powder.

14. A method as claimed in Claim 13, wherein said thermographic powder includes metallic particles.

15. A method of printing a simulated engraved image, which comprise the steps of: is preparing a negative of an image; preparing a lithographic printing plate from said negative; 20 preparing an emboss plate from said negative; affixing said lithographic printing plate to a print cylinder; 25 affixing said emboss plate to an emboss cylinder; transferring ink from said lithographic printing plate to a blanket cylinder in registration with said emboss plate; rotating said emboss cylinder and said blanket cylinder with media to be printed therebetween, thereby to print said image on one side of said media and emboss said image on the other side of said media.

- is -

16. A method as claimed in Claim 15, wherein said step of preparing said emboss plate includes the steps of:

applying a photo-resist to an acid etchable sheet; 5 exposing said photoresist to light through said negative' removing unexposed photo-resist from said sheet; acid etching said sheet to form a raised image.

17. A method of applying a simulated engraved image to a substrate, substantially as hereinbefore described with reference to Figure 2, or Figure 2 with Figures 1 and 3, of the accompanying drawings.

18. A printing system substantially as hereinbefore described with reference to Figure 2, or Figure 2 with Figures 1 and 3, of the accompanying drawings.

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