WO2013030817A2

WO2013030817A2 - Printing system and method of printing

Info

Publication number: WO2013030817A2
Application number: PCT/IL2011/000700
Authority: WO
Inventors: Naseem Yacoub; Raia Slivniak; Michael BOBRITSKY; Shikma LITMANOVITZ
Original assignee: Hewlett-Packard Indigo B.V.
Priority date: 2011-08-31
Filing date: 2011-08-31
Publication date: 2013-03-07
Also published as: WO2013030817A3

Abstract

According to an aspect of one example of principles described herein, a printing system is provided. The printing system comprises module that includes an intermediate transfer module onto which images to be printed are transferred and from which images are subsequently transferred to a web of media during a printing operation. The printing system is arranged to enable lateral displacement of the web relative to the intermediate transfer module. The printing system further comprises a printer controller which determines a lateral displacement strategy, and controls, during a printing operation, the relative lateral displacement of the intermediate transfer module and the web in accordance with the determined displacement strategy.

Description

PRINTING SYSTEM AND METHOD OF PRINTING

BACKGROUND

Some printing techniques, such as liquid electro-photographic (LEP) printing, generate an image on a photoreceptor drum and transfer the generated image to a substrate via an intermediate transfer member (ITM). In such printing techniques the ITM is typically covered with a replaceable blanket.

As blankets become used over time, their replacement is recommended in order to maintain high print quality. However, blanket replacement is costly both in terms of price, and in terms of printer downtime.

BRIEF DESCRIPTION

Examples and embodiments of the invention will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

Figure 1 is a simplified plan view of a printing system according one example; Figure 2 is a simplified side view illustrating elements of the printing system of Figure 1 according to one example;

Figure 3 is a simplified plan view of an intermediate transfer member according to one example;

Figure 4 is a simplified flow diagram outlining a method of operating a printing system according to one example;

Figure 5 is a simplified flow diagram outlining a method of operating a printing system according to one example;

Figure 6 is a simplified plan view of a printing system according to one example;

Figure 7 is a simplified plan view of a printing system according to one example;

Figure 8 is a simplified side view illustrating elements of the printing system of

Figure 7 according to one example;

Figure 9 is a simplified flow diagram outlining a method of operating a printing system according to one example; and

Figure 10 is a block diagram outlining a printer controller according to one example. DETAILED DESCRIPTION

In printers that use intermediate transfer members (ITMs), particularly on so- called industrial printers, printing is often performed on fixed-width webs or rolls of substrate. It is known, however, that over time the edges of the webs can cause damage to the blanket.

If printing is done primarily with fixed-width webs, any damage caused to the blanket by web edges will generally not adversely affect print quality since the damaged areas of the blanket will generally correspond to the web edges. However, if the same blanket is used for printing on different width webs, the aforementioned damage may become noticeable, especially when printing is performed initially on a first width web and subsequently on a wider web. In this case, damage to the blanket caused by printing on a narrow web may lead to lines or print quality issues being visible on printing performed subsequently on wider webs.

To overcome such problems printer operators are generally advised to perform printing in the order of widest web to narrowest web. In this way, a narrower web may be arranged not to use areas of a blanket damaged by edges of a wider web.

However, in many situations, it is not always possible to ensure that such guidelines are followed. Accordingly, if damage is caused to a blanket the only solution to maintain high print quality is to replace the blanket. However, as previously mentioned, blanket replacement is costly both in terms of price and in terms of printer downtime.

Referring now to Figure 1 , there is shown a simplified plan view of an outline printing system 100 according to one example.

The printing system 100 includes an un-winder module 102 on which is positioned a web of substrate 104. The web of substrate 04 is provided, for example, on a roll, and has a substantially fixed width throughout the length of the roll. The web 104 feeds through a web guide unit 106 and onto a printing module 108 where images or other recordings may be printed onto the web on a printable area 1 10. Although printed area 1 10 is shown as extending to, or substantially to, the lateral edges of the web 104, in some examples the printable area 1 10 may not cover the entire width of the web 104.

The web guide unit 106 is used to control the lateral position of the web 104 within the printing module 108 to maintain the web at a predetermined lateral reference printing position within the printing module 108. The web guide unit 106 may, for example, use moveable mechanical guides to adjust the web path through the printing module 108 and such guides may, for example, be moveable in response to signals from web position sensors (not shown) to ensure that the web 104 is suitably positioned within the printing module 108.

The web 104 is then wound onto a roll at a winder module 1 12. The web therefore advances in the direction of the arrow 1 14 which also indicates the printing axis. Referring now to Figure 2 there is shown a simplified side view of elements of the outline printing system 100 shown in Figure 1 according to one example. The printing module 108 comprises a development or writing module 202 that creates an image to be printed on a developer roller 204. For example, the development module 202 may, in one example, be a liquid electro-photographic (LEP) development module and the development roller 204 may be a photo imaging plate (PIP). An image created on the development roller 204 is then transferred to the blanket of the intermediate transfer module 206 before being transferred to the web 104 using an impression drum 208. A printer controller 210 is also shown that controls, either directly or indirectly, the key aspects of the printing system 100 including the un-winder module 102, the web guide unit 106, the printing module 108, and the winder module 1 12. Although shown as being located in the printing module 108 in other examples the printer controller may be located elsewhere within the printing system 100.

The printing system 100 is designed to print on webs having a maximum width WMAX, as shown in Figure 1. Webs having a width narrower than WMAX may, however, be used.

According to one example, printing on a web having a width narrower than W_MAX may be achieved, as will be described in further detail below, in such a way that damage caused to the blanket of the ITM 206 by web edges is eliminated, or at least significantly reduced. Advantageously, this may help reduce the frequency of blanket replacement resulting in both cost and downtime savings.

In the present example, when printing on a web narrower than WMAX the printing system 100 modifies, during a printing operation, the lateral position of the web 104 relative to the blanket of the ITM 206 such that during a printing operation the edges of the web do not remain in contact with the same part of the blanket for the whole duration of the printing operation. In one example, lateral movement of the web during a printing operation may be accompanied by a corresponding lateral displacement of the image or images formed on the blanket of the ITM 206. In this way, the lateral position of printed images relative to the web remains unchanged and printing operations are printed as intended.

In a further example, no corresponding lateral movement of image or images formed on the ITM 206 blanket is performed. This may be appropriate, for example, if images formed on the ITM 206 blanket may be satisfactorily transferred to a web that has been laterally displaced - in other words that the image to be transferred fits entirely within the width of the web - and that any such displacement is acceptable to the printer operator. A method of operating the printing system 1 00 according to an example will now be described with additional reference to Figures 3, 4, and Figure 5.

Figure 3 is a plan view of the ITM 206 blanket. The ITM 206 has a first and second positions BLEFT and BRIGHT corresponding respectively to the left and right edges (when viewed in the printing direction 1 14 shown in Figures 1 and 2) of the effective printable area on the blanket of the ITM 206 onto which images may be transferred from the developer roller 204. The maximum width web W AX usable with the printing system is thus equal to the distance between BRIGHT and BLEFT- Depending on the particular characteristics of the printing system 100, the positions B_LEFT and BRIGHT may or may not correspond to the physical edges of the blanket of the ITM 206.

The position BLEFT may in some examples be considered as the reference printing position of the printing system 100.

At 402 (Figure 4) the printer controller 210 obtains the width W_WEB on which a printing operation is to be performed and also obtains the position of the web relative to the blanket. In one example the width of a web loaded into the printing system 100, such as the web 304, is obtained automatically by the printing system 100, for example, through use of appropriate sensors. For example, one sensor may detect or measure the left-hand offset position (OLEFT) of the left- hand edge (W_LEFT) of the web relative to the blanket edge BLEFT, and may detect or measure the right-hand offset position (ORIGHT) of the right-hand edge (WRIGHT) of the web relative to the blanket edge BRIGHT- The width of the web W_WEB may then be calculated.

In various examples the sensors may be incorporated into at least one of the unwinder module 102, the web-guide unit 106, the printing module 108, or the winder module 1 12. In a further example, the width of the web and the position of the web relative to the edges of the blanket of the ITM 206 may be obtained via a user interface (not shown) from a printer operator. At 404 the printer controller 210 determines a web displacement strategy which defines how the lateral position of the web is to be modified during the course of the printing operation. At 406 the printer controller 210 starts performing a printing operation, for example, after having received or obtained a print job to be printed.

During the printing operation, the printer controller 210 modifies (408) the lateral position of the web in accordance with the determined web displacement strategy, for example by issuing appropriate signals or instructions to the web guide unit 106. The printer controller 210 applies the determined web displacement strategy until the printing operation completes. In one example the web displacement strategy may be implemented by a series of small displacement steps. In another example the web displacement strategy may be implemented in a continuous manner.

In a further example, as shown in Figure 5, the printer controller 210 additionally modifies (502) the lateral position of the image or images transferred onto the ITM 206 in a corresponding manner to the lateral displacement of the web, for example in accordance with the web displacement strategy. This may be achieved, for example, by adding a lateral offset to image data to be printed prior to an image being formed on the PIP 204. In this way, images printed on the web during the printing operation remain aligned with the web as originally intended. In one example the printer controller 210 determines a web displacement strategy that oscillates the lateral position of a web during a printing operation between the left-hand (B_LEFT) and right-hand (BRIGHT) positions on the ITM 206. For example, the determined web displacement strategy may cause the printer controller 210 to control the web guide unit 108 to laterally displace the position of the web in one direction until the position of one of the web edges (WLEFT or WRIGHT) on the ITM 206 corresponds to a respective left and right displacement limit. The printer controller 210 may then reverse the direction of the web displacement such that during the printing operation, depending on the length of web of used and the oscillation frequency, the web oscillates between the left and right displacement limits. It should be noted, however, the displacement limits do not allow lateral displacement of a web edge beyond the blanket edges Bi_EFT or BRIGHT-

In one example, the web displacement strategy displaces the web laterally in an oscillating manner at a rate of about 5 microns or micrometres per meter, with the left and right displacement limits being respectively set at around 15mm from the respective left and right-hand edges of the web, giving a maximum lateral displacement amplitude of about +/- 15mm.

In one example, the web displacement strategy displaces the web laterally in an oscillating manner at a rate of between about 5 to 200 microns per meter, with the left and right displacement limits being set up to about 50mm from the left and right-hand edges of the web, giving a maximum lateral displacement amplitude of about +/- 50mm.

In a further example, different lateral web displacement rates may be chosen for each direction of the displacement. For example, in a first direction the rate of lateral web displacement may be about 50 microns per meter, whereas in the reverse direction a lateral web displacement rate may be about 100 microns per meter.

In a still further example, different web displacement amplitudes may be chosen for each direction of the displacement to cause web displacement in an asymmetrical manner. For example, in a first direction the amplitude of the lateral web displacement may be about 15mm, and in the reverse direction may be about 25mm. This may be useful, for example, where a web is positioned close to the one of the edges of the ITM 206.

The rate of lateral displacement and the maximum lateral displacement amplitude may be modified, for example, depending on technical characteristics of the web material or desired print quality. For example, higher rates of web displacement and/or displacement amplitude may be possible with webs having a high degree of flexibility, whereas lower rates of web displacement and/or displacement amplitude may be more suitable with webs having a lower degree of flexibility. In any case, the rate of lateral displacement and/or the amplitude of web displacement should be chosen to avoid damage, such as creasing, tearing, stretching, shearing, etc. occurring to webs, and to avoid distortion of images printed thereon. In one example technical characteristics of the web material may be obtained, for example, from a web material sensor, a printer operator, or other suitable identification system.

In further examples different rates of displacement and/or different displacement amplitudes may be used.

In different examples the web displacement strategy may be represented by a mathematical formula, a XML script, one or more logic instructions, a script, and the like. In one example the web displacement strategy defines an oscillating waveform having a frequency and an amplitude.

Referring now to Figure 6 there is shown a simplified block diagram of a printing system 600 according to a further example. In this example, the printing system 600 includes a first web guide unit 602 and a second web guide unit 604.

First web guide unit 602 is positioned between the un-winder module 102 and the printing module 108 and second web guide unit 604 is positioned between the printing module 108 and the winder module 104. In one example the first web guide unit 602 may be positioned within the un-winder module 102. In a further example the second web guide unit 604 may be positioned within the winder module 104. In this example, under control of the printer controller 1 10, the first web guide unit 602 modifies the lateral displacement of a web on the ITM 106 in accordance with a determined web displacement strategy, and the second web guide unit 604 modifies the lateral displacement of the web such that as the web is wound on winder module 104 the edges of the wound web are substantially straight.

In a yet further example, as shown in Figures 7 and 8, a printing system 700 has an un-winder module 02, a printing module 702, and a winder module 104. The printing module 702 comprises a developer roller 804, an intermediate transfer module 806, and an impression drum 808. The printing system 700 operates in accordance with the method shown in the flow diagram of Figure 9. In this example at least the intermediate transfer module 806 is laterally moveable such that, under control of a printer controller 810, the lateral position of at least the intermediate transfer module 806 (including the blanket covering the ITM) relative to the web 104 is modified (902) in accordance with the determined web displacement strategy. In this example, the web 104 is not displaced laterally, but at least part of the printing module 702 is displaced laterally, in accordance with a determined web displacement strategy, thereby avoiding or reducing the edges of the web 104 from damaging the blanket of the ITM 806. In this example it should be noted that the web displacement strategy defines relative lateral displacement of a web and the intermediate transfer module 806.

In a further example, as illustrated in Figure 10, the printer controller, such as printer controller 210 or 810, may be implemented using a microprocessor 1002 coupled, via a communication bus 1004, to a memory 1006 and an input/output module 1008. The memory 1006 stores web displacement strategy determination instructions 1010 and printer controller instructions 1012. The instructions 1010 and 1012 are processor understandable instructions that when executed by the processor 1002 control a printing system in accordance with methods described herein.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

Claims

1. A printing system comprising a printing module including an intermediate transfer module onto which images to be printed are transferred and from which images are subsequently transferred to a web of media during a printing operation,

wherein the printing system is arranged to enable lateral displacement of the web relative to the intermediate transfer module; and wherein the printing system further comprises a printer controller to:

determine a lateral displacement strategy; and

control, during a printing operation, the relative lateral displacement of the intermediate transfer module and the web in accordance with the determined displacement strategy.

2. The printing system of claim 1 wherein the intermediate transfer module further comprises a removable blanket.

3. The printing system of claim 1 , further comprising a web guide unit located in a web un-winder module, or between the web un-winder module and the printing module, to laterally displace the web relative to the intermediate transfer module in accordance with the determined web displacement strategy.

4. The printing system of claim 1 , wherein the lateral displacement strategy is determined to cause the printer controller to laterally displace the web at a rate of between about 5 microns to 200 microns per meter of web.

5. The printing system of claim 1 , wherein the lateral displacement strategy is determined to cause the printer controller to laterally displace the web in an oscillating manner with a maximum amplitude of between about +/- 5mm and +/- 50mm.

6. The printing system of claim 3 further comprising a further web guide unit located between the printing module and a web winder unit, or within the web winder unit, the further web guide unit being arranged to modify the lateral displacement of the web prior to it being wound on the winder unit such that the lateral edges of the wound web are substantially aligned on the winder unit.

7. The printing system of claim 1 wherein at least some of the elements of the printing module are laterally moveable relative to the web in accordance with the web displacement strategy.

8. The printing system of claim 1 , wherein the printer controller is further arranged to laterally displace images transferred onto the intermediate transfer module in accordance with the web displacement strategy.

9. A method of printing with a printer having an intermediate transfer module comprising a blanket onto which images to be printed are transferred and from which images are subsequently transferred to a portion of a web of media during a printing operation, the method comprising:

generating a web displacement strategy;

performing a printing operation; and

controlling, during the printing operation, the lateral position of the web relative to the blanket in accordance with the generated web displacement strategy.

10. The method of claim 9 further comprising determining the width of a web loaded in the printer and position of the web relative to the blanket, and identifying technical characteristics of the web, and wherein the step of generating a web displacement strategy is based at least in part on at least one of: the determined web width, the determined web width, and identified web technical characteristics.

1 1. The method of claim 9, further comprising laterally displacing, during the printing operation, images transferred to the blanket in accordance with the generated web displacement strategy.

12. The method of claim 9, wherein the step of generating a web displacement strategy generates a strategy that is used to laterally displace the web relative to the blanket at a rate of between about 5 to 200 microns per meter of web printed on.

13. The method of claim 9, wherein the step of generating a web displacement strategy generates a strategy that is used to laterally displace the web in an oscillating manner with a maximum displacement amplitude of between about +/- 15mm and +/- 50mm.

14. The method of claim 9 wherein the step of controlling comprises laterally displacing the position of the web during the printing operation.

15. A printing system comprising a printing module including an intermediate transfer module comprising a blanket onto which images to be printed are transferred and from which images are subsequently transferred to a web of media during a printing operation, the printing system comprising:

a web guide unit to laterally displace a web relative to the intermediate transfer module; and

a printer controller to:

determine an oscillating web displacement strategy, the displacement strategy being based at least in part on at least one of the width of the web, the width of the blanket, the position of the web relative to the intermediate transfer module, and the technical characteristic of the web; and

control the web guide unit to laterally displace the web relative to the intermediate transfer element in accordance with the determined web displacement strategy.