WO2004037543A2

WO2004037543A2 - Advancing system and method for a digital printing apparatus

Info

Publication number: WO2004037543A2
Application number: PCT/IL2003/000874
Authority: WO
Inventors: Gregory Rodin; Michael Zino
Original assignee: Nur Macroprinters Ltd.
Priority date: 2002-10-24
Filing date: 2003-10-23
Publication date: 2004-05-06
Also published as: AU2003278563A1; WO2004037540A3; WO2004037540A2; WO2004037543A3; AU2003278563A8; AU2003274664A1

Abstract

A printer apparatus is presented comprising a printing head system and an advancing system. The printing head includes a print head assembly mounted for movement along at least one horizontal axis with respect to a printing area. The advancing system is configured and operable for enabling to selectively locate the printing area in either one of a first and a second printing planes arranged in vertically spaced-apart relationship, thereby selectively exposing the first or second printing plane to the print head assembly for printing. The first and second printing planes are defined by, respectively, a first flat-bed assembly and a second roll-to-roll assembly of the advancing system.

Description

ADVANCING SYSTEM AND METHOD FOR A DIGITAL PRINTING APPARATUS

FIELD OF THE INVENTION

This invention is generally in the field of digital printing techniques, and relates to an advancing system and method for use in digital printers.

BACKGROUND OF THE INVENTION Various printer configurations have been developed for printing on various information-carrying materials such as paper, adhesive vinyl, fabrics and PVC. Two such configurations are the so-called "roll-to-roll" and "flat-bed" configurations.

In general terms, "roll-to-roll" printers utilize an advancing system configured to displace a flexible substrate in a given feed direction with respect to a print head by means of rollers. As for the "flat-bed" (also called "rigid") printers, their advancing system utilizes a rigid support for a substrate (not necessarily flexible) or a rigid substrate driven for back and forward movement with respect to a print head.

In all printing technologies, advancing systems need to provide high level of accuracy in registering a substrate (generally, information-carrying materiel) and ensuring accurate positioning of the print head over the information-carrying materiel, for precise printing. For wide-format printing (e.g., of about 0.7 meter length of the printing line) and very wide format printing (up to 5 meter length of the printing line), the requirement for a high level accuracy of the advancing system is even more critical, as even a small deviation in the proper registration and positioning of the substrate and the print head may result in a noticeable printing defect. US patent no. 6,296,403 discloses a dual-mode printer for printing on both flexible and rigid substrates. The dual-mode printer includes a table providing a substantially planar support surface for supporting a substrate. A flexible-substrate feed system is configured to feed a flexible substrate in a given feed direction across the support surface. The printer has a print head configured for depositing a printing medium on a substrate as part of a printing process. A motion system is configured to generate relative displacement between the print head and the support surface in at least a first direction parallel to the feed direction. This combination of components allows the printer to be used in a flexible-substrate mode in which relative displacement between the substrate and the print head is generated at least in part by the flexible-substrate feed system and in a rigid-substrate mode in which relative displacement between the substrate and the print head is generated exclusively by the motion system.

SUMMARY OF THE INVENTION There is a need in the art to facilitate integration of "roll to roll" and "rigid"

(or "flat bed") advancing systems within a printing apparatus, as well as to improve "flat bed" configuration, which is particularly useful for wide and very wide format printing.

According to one aspect of the present invention, there is provided a printer apparatus comprising a printing head system including a print head assembly mounted for movement along at least one horizontal axis with respect to a printing area; and an advancing system configured and operable for enabling to selectively locate the printing area in either one of a first and a second printing planes arranged in vertically spaced-apart relationship, thereby selectively exposing the first or second printing plane to the print head assembly for printing, the first and second printing planes being defined by, respectively, a first flat-bed assembly and a second roll-to-roll assembly of the advancing system.

The first flat-bed assembly of the advancing system comprises a first table defining the first printing plane and mounted for reciprocating movement in a horizontal plane between its operative position being located in the printing area and inoperative position being located outside the printing area.

The second roll-to-roll assembly may be constituted by a second table defining the second printing plane and stationary mounted so as to be aligned with the printing area. The second table is located between loading and unloading rollers' assemblies.

Alternatively, the roll-to-roll assembly may be constituted by the same first table movable into its lower position to define the second printing plane. The table, when in the lower position, is located between loading and unloading rollers' assemblies.

The preferred configuration is such that the first table by its opposite sides is mounted on first and second spaced-apart guiding rails via first and second conveyor assemblies, respectively. One of the first and second conveyor assemblies includes a driving conveyor being operated by a motor for moving the table along the guiding rail axis, and the other conveyor assembly is driven for operation by the movement of the first table caused by the first conveyor assembly.

Preferably, the advancing system also comprises a drive assembly associated with the print head assembly for driving it for vertical movement with respect to the printing area. According to another aspect of the present invention, there is provided a method for use in a printer apparatus including a printing head assembly and an advancing system, the method comprising:

- defining by said advancing system first and second horizontal printing planes arranged in vertically spaced-apart relationship, for locating an information carrier in either one of the first and second printing planes, said and second printing planes being defined by, respectively, a first flat-bed assembly and a second roll-to-roll assembly of the advancing system;

- operating the advancing system so as to selectively locate a printing area in either one of the first and second printing planes, thereby selectively exposing the first or second printing plane to the print head assembly for printing.

According to yet another aspect of the present invention, there is provided a printer apparatus comprising a printing head assembly; and an advancing system defining a printing area and configured for moving the printing area along a horizontal axis with respect to the print head assembly, the advancing system comprising first and second guiding rails arranged in a spaced-apart parallel relationship and extending along said horizontal axis, and a table mounted by its opposite sides on said first and second guiding rails via first and second conveyor assemblies, respectively, wherein one of the first and second conveyor assemblies includes a driving conveyor being operated by a motor for moving the table along the guiding rail axis and the other conveyor assembly is driven for operation by said movement of the table caused by the first conveyor assembly.

The present invention, according to its yet another aspect, provides a method of fabricating a silk-screen stencil, the method comprising applying a digital inkjet printing apparatus to a screen fabric to create a pattern thereon by a UV-curable ink, the stencil being thereby ready for further silk screen printing..

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carried out in practice, a preferred embodiment will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

Fig. 1 is a schematic illustration of a digital printer system according to the invention;

Fig. 2 more specifically illustrates an advancing system used in the printer of Fig. 1;

Figs. 3A to 3E exemplify the implementation of the advancing system of Fig. 2;

Fig. 4 is a schematic illustration of a combined printer apparatus according to the invention configured to operate with both flat bed and roll-to-roll modes; Fig. 5A and 5B illustrate the relative positions and movements of the printing head system and advancing systems in the combined printer apparatus of Fig. 4;

Fig. 6A schematically illustrates the principles of the state in the art "silk screen" manufacturing process; and

Fig. 6B illustrates how the technique of the present invention allows for the stencil manufacture process easily performed in the single phase by a digital inkjet printing apparatus.

DETAILED DESCRIPTION OF THE INVENTION Referring to Fig. 1, there is illustrated a digital printer system 1 according to the invention. The printer 1 utilizes a combined "flat bed" and "roll-to-roll" advancing system according to the invention, particularly for use in wide and very wide format printing. The printer 1 thus comprises such main constructional parts as a printing head system (which is not specifically shown here) accommodated within a housing 2; and an advancing system 4.

The printing head system typically comprises a print head assembly associated with a drive means for displacing the print head assembly in a horizontal plane across the information carrier. The print head assembly may be of any known design, for example that commercially available from Nur Macroprinters, Israel, and therefore its construction and operation need not be specifically described. It should be noted that the present invention is not limited to any specific type of a print head assembly.

The advancing system 4 is configured for supporting the information carrier and moving it in a horizontal plane relative to the housing 2 (i.e., relative to the print head system). Additionally, the advancing system 4 is configured for displacing the print head assembly in a vertical plane with respect to a printing plane, as will be described more specifically further below.

The advancing system 4 comprises a first assembly for "flat bed" printing. This assembly includes two guiding arms 5 and 6 arranged in a spaced-apart parallel relationship so as to be at opposite sides of the print head assembly, and a table 8 for holding an information carrier IC during the printing process. The table 8 is mounted on the guiding arms 5 and 6 and driven for reciprocating movement along the axes of the arms, to thereby translate the information carrier with respect to the print head assembly.

Also provided in the advancing system 4 is a second roll-to-roll assembly, which can be seen in Fig. 4 and will be described further below. The roll-to-roll assembly is accommodated so as to define a printing plane underneath that defined by the flat bed assembly. To enable a shift from the flat bed to the roll-to-roll operational mode, the table 8 is moved in the horizontal plane so as to be outside a printing area, thus exposing the roll-to-roll printing plane for printing.

Additionally, the advancing system 4 includes a drive mechanism (not shown here but seen in Fig. 2) associated with the print head assembly for moving the print head assembly in a vertical direction, to enable a shift between the flat bed and roll-to-roll operational modes.

It should be noted that the principle of the present invention consisting of combining the flat bed and roll-to-roll configurations in a common advancing system are not limited to any specific design of the flat bed or roll-to-roll assemblies. The only requirement to these designs is that the flat bed and roll-to-roll assemblies define first and second horizontal printing planes, respectively, that can be arranged one above the other.

As more specifically shown in Fig. 2, the movement of table 8 is implemented by providing two guiding rails 10 and 11 mounted in and extending along the guiding arms 5 and 6, respectively, and providing the table at opposite sides thereof with two conveyor assemblies (not shown here) mounted on the guiding rails for movement therealong. According to another aspect of the present invention, one of the conveyor assemblies is a driving assembly (e.g., a first array of wheels rotatable by a motor), and the other conveyor assembly is a driven one (a second array of freely rotatable wheels). Thus, the table 8, along its one side 8A, is supported on the driving conveyor assembly to thereby provide the reciprocation of the table along the axis of the rail 10, and, along its other opposite side 8B, is supported on the driven conveyor assembly driven for rotation by the movement of the table itself. This configuration thus requires a single driving mechanism only at one side of the table and thereby eliminates the need for adjusting two driving mechanisms at opposite sides of the table to provide the table registration. In an exemplary and non-limiting configuration, table 8 is a 2x3.2m table, and the rails 10 and 11 are of a 6m length. Generally, the length of the rails is such as to enable movement of the table along the rails up to the complete displacement of the table from the printing area to allow printing ink access to an information carrier in the roll-to-roll printing plane.

Fig. 3 A illustrates the table 8 (e.g., of a 3.2m width and 2m length) supported on the conveyor assemblies 12 and 13 associated with the rails 10 and 11, respectively. The assembly 12 (an arrays of wheels or a conveyor belt) is attached to the table along its side 8A and is operated by a motor system 12A for driving the rotation of the wheels (or belt) and thus driving the movement of the table. The assembly 13 (wheels or conveyor belt) just supports the bottom side 8B of the table and is driven for rotation by the movement of the table, caused by rotation of the first conveyor assembly 12. Figs. 3B and 3C more specifically exemplify the assembly 12 formed by an array of rotatable wheels, generally at 12B, and the motor system 12A in the form of a conveyor belt system. Fig. 3D and 3E exemplify the driven assembly 13 in the form of an array of freely rotatable wheels, generally at 13B.

Digital printing techniques typically require the precision of the information carrier movement in the order of microns. The present invention provides for controlling the precise movement of a single mechanical mechanism. This can be implemented by utilizing a precise motor system 12A associated with the conveyor assembly 12, or by an optical encoder or analog potentiometer controlling the movement of the assembly 12. In order to achieve the synchronous movement of both sides 8A and 8B of the table and prevent the misregistration (tilt) of the upper surface of the table with the single driving mechanism, the table itself should be of sufficient rigidity and weight. For example, the table can be a custom-made aluminum honeycomb vacuum table, such as those commercially available from Cellbond UK, having a 80- 100mm thickness and about 100kg weight.

It should be understood that the physical parameters of the table (rigidity and weight) are defined by a specific application, namely, the printing format: the smaller the format width, the less the requirements to the rigidity and lightness of the table. It should also be understood that the driving and driven conveyor assemblies could be of any known type of the kind proving a reciprocating movement of the table in a controllable manner.

It should be noted, although not specifically shown, that a third arm can be provided in between the arms 5 and 6 and installed with a suitable guiding rail and driven translating (conveyor) assembly. This allows for using even larger and heavier table when needed, while not affecting the complicity of the mechanical mechanism and its control.

Reference is now made to Fig. 4 more specifically illustrating the integrated digital printer apparatus 1 whose advancing system 4 utilizes both "flat bed" and "roll-to-roll" configurations and which is configured so as to enable the selective operation of one of these configurations. The same reference numbers are used to identify the components which are common in Figs. 1 and 4.

As described above, the flat bed assembly of the advancing system 4 is composed of two parallel arms 5 and 6 installed with guiding rails 10 and 11, respectively, for supporting the table 8 at its opposite sides. The flat bed assembly defines a printing plane P_! below a print head assembly 26 (the so-called "carriage"). The latter is typically mounted on a guiding arm 26A extending across the information carrier for movement along the axis of the arm.

A roll-to-roll assembly, generally at 24, of the advancing system 4 typically utilizes a loading pair of rolls (not shown here) and an unloading pair of rolls R₂, and a stationary mounted table 20 between the loading and unloading rolls for defining a printing plane P₂ and for supporting the information carrier therein. The rotation of the rolls provides for advancing movement of the information carrier clamped between the rolls, so as to supply successive printing areas onto the table 20. The assembly 24 is configured such that the printing plane P₂ is below the printing plane Pi defined by the flat bed assembly of the advancing system, for example at a distance of about 10mm.

Further provided in the advancing system 4 is a drive assembly 26B associated with the guiding arm 26A (that movably supports the print head assembly 26), preferably with the opposite ends of the arm 26A. The drive assembly 26B drives a movement of the arm 26A with the print head 26 along a vertical axis between its first upper and second lower operational positions corresponding to the flat bed and roll-to-roll operational modes, respectively..

The operation of the apparatus 1 will now be described with reference to Figs. 5A and 5B schematically illustrating two operative positions of the printer apparatus 1, respectively. In the position of Fig. 5A, the printer apparatus is adjusted to operate in the flat bed mode. To this end, the advancing system 4 operates to move the printing head 26 into its upper position and to bring the movable table 8 with the information carrier thereon into its operative position, i.e., located between the printing head 26 (carriage) and the stationary table 20. In the position shown in Fig. 5B, the printer apparatus is adjusted to operate in the roll-to- roll mode: The advancing system 4 operates to move and keep the table 8 aside the printing head system (i.e., to be in its inoperative position), and to move the printing head into its lower operative position so as to be applied to the information carrier on the stationary table 20.

It should be noted that, generally, the drive assembly 26B can be alternatively or additionally associated with the roll-to-roll transfer system (i.e., two pairs of rolls and the table 20 therebetween) to displace the roll-to-roll defined plane P₂ along a vertical axis. It should also be understood that considering the vertical movement of the print head assembly, the construction may be such that the guiding arm 26A defines two vertically spaced-apart axes for the print head movement along each of these axes, and the drive mechanism 26B operates to shift the print head assembly 26 between these axes to print on, respectively planes Pi and P₂. It should be understood that the vertical movement of the print head 26 is controlled taking into account the fact that digital printing typically requires a certain small distance (e.g., about 2mm) between a printing head and an information carrier during the printer operation. The vertical displacement of the printing head system 26 is thus carried out in a controllable manner so as to ensure that the printing head itself is kept at the same distance from the information carrier all along the printing head length. Keeping in mind that the displacement for small distances is needed (e.g., for up to 150mm), any known suitable means can be used for controlling the movement of the printing head, such as shaft encoder capable of synchronizing the operation of mechanical mechanisms associated with opposite sides of the printing head system.

It should be noted, although not specifically shown that selectively locating a printing area in either one of the first and second printing planes PI and P2 can be achieved with the single table mounted for vertical movement. In this case, the table, when in its lower position is aligned with the roll-to-roll material feeding conveyor and thus serves for supporting the information carrier in the roll-to-roll printing configuration. When in the upper position of the table, corresponding to flat-bed mode, the table is mounted for movement in a horizontal plane with respect to the print head assembly. The use of the single-table configuration, however, requires a somewhat disabling of the roll-to-roll assembly to shift the table into the flat-bed operational mode, i.e., requires removal from the table an information carrier conveyed therethrough during the roll-to-roll operation. The use of the above-described two-table configuration advantageously allows for keeping the roll-to-roll assembly unchanged when shifting to the flat-bed operational mode.

The present invention also provides for a digital printing technique specifically suitable to be used with "silk screen" printing technology. "Silk screen" printing is an old and well-established art, which employs a screen, namely supported stencil to provide a dense and opaque layer of ink on a substrate. The name "silk screen" comes from the threads originally used to support the various individual elements of the stencil. Today, this printing process enjoys widespread commercial application and is used to print on such diverse items as dishes, dials, poster boards, plexiglass sheets, textiles and silicon wafers. In the electronics industry, the process is sometimes referred to as thick-film printing.

A typical "silk screen" process, as shown in self-explanatory manner in Fig. 6 A, involves two phases: stencil manufacture and stencil printing. In the manufacture of a stencil, the screen fabric (generally polyester, not silk) is stretched tightly across a stable frame to which it is adhered. This stretched screen is then coated with a photosensitive emulsion. The positive of a film, containing an opaque image on a clear film base of the art to be printed, is placed in contact with the bottom of the emulsion-coated screen. Both the film-positive and the screen are then placed in a vacuum frame to be below a glass plate.

The emulsion coated screen is photo exposed by beaming a strong light through the glass of the vacuum frame to harden all emulsion not masked from the light by the opaque lines of the film positive. The exposed screen is then removed from the vacuum frame to be dampened by a spray of water that dissolves all unhardened areas completing the stencil making process. By the end of this process, the stencil is ready for printing i.e., each of the stencil pinholes is either blocked or left unblocked to allow the passage of ink therethrough, to create the outline of the image to be printed.

The present invention allows the stencil manufacture process to be easily performed by a digital inkjet printing apparatus utilizing drop on demand technology. As shown in Fig. 6B, according to the present invention, the screen fabric (e.g. polyester) is stretched tightly across a frame, and the screen frame is then put on the "flat bed" vacuum table (that may for example be table 8 of apparatus 1 previously described) to thereby present an information carrier. The vacuum table then transfers the screen fabric with respect to the printing head system. The printing head system operates to print the image onto the stencil by dropping blocking material (such as UN-curing ink or wax-ink) onto selective pinholes according to printing digital data. The stencil is ready for further silk screen printing without the need for additional chemical processing.

Claims

CLAIMS:

1. A printer apparatus comprising a printing head system including a print head assembly mounted for movement along at least one horizontal axis with respect to a printing area; and an advancing system configured and operable for enabling to selectively locate the printing area in either one of a first and a second printing planes arranged in vertically spaced-apart relationship, thereby selectively exposing the first or second printing plane to the print head assembly for printing, the first and second printing planes being defined by, respectively, a first flat-bed assembly and a second roll-to-roll assembly of the advancing system.

2. The apparatus of Claim 1, wherein said first flat-bed assembly of the advancing system comprises a first table defining said first printing plane and mounted for reciprocating movement in a horizontal plane between its operative position being located in the printing area and inoperative position being located outside the printing area.

3. The apparatus of Claim 1 or 2, wherein said second roll-to-roll assembly comprises a second table defining the second printing plane and stationary mounted so as to be aligned with the printing area, the second table being located between loading and unloading rollers' assemblies.

4. The apparatus of Claim 1 or 2, wherein said first table is movable into its lower position to define the second printing plane, said first table when in the lower position being located between loading and unloading rollers' assemblies.

5. The apparatus of any one of preceding Claims, wherein said advancing system comprises a drive assembly associated with the print head assembly for driving it for vertical movement with respect to the printing area, so as to be exposed for printing on either one of the first and second printing planes.

6. The apparatus of any one of Claims 2 to 5, wherein said first table by its opposite sides is mounted on first and second spaced-apart guiding rails via first and second conveyor assemblies, respectively, wherein one of the first and second conveyor assemblies includes a driving conveyor being operated by a motor for moving the table along the guiding rail axis and the other conveyor assembly is driven for operation by said movement of the first table caused by the first conveyor assembly.

7. A method for use in a printer apparatus including a printing head assembly and an advancing system, the method comprising:

8. A printer apparatus comprising a printing head assembly; and an advancing system defining a printing area and configured for moving the printing area along a horizontal axis with respect to the print head assembly, the advancing system comprising first and second guiding rails arranged in a spaced-apart parallel relationship and extending along said horizontal axis, and a table mounted by its opposite sides on said first and second guiding rails via first and second conveyor assemblies, respectively, wherein one of the first and second conveyor assemblies includes a driving conveyor being operated by a motor for moving the table along the guiding rail axis and the other conveyor assembly is driven for operation by said movement of the table caused by the first conveyor assembly.

9. A method of fabricating a silk-screen stencil, the method comprising applying a digital inkjet printing apparatus to a screen fabric to create a pattern thereon by a UV-curable ink, the stencil being thereby ready for further silk screen printing..