CUTTER MODULE AND METHOD

A cutter module comprises an active rotary cutting blade driven by a blade drive, a passive cutting blade opposite the active rotary cutting blade, and a traction mechanism to pinch a medium to be cut in an area adjacent to the active rotary cutting blade and the passive cutting blade.

BACKGROUND

Some printers include a cutting device which can cut a print medium before or after a printing operation. The cutting device may include a cutting blade supported on a carriage to move across a print zone. By movement of the carriage across the print zone and/or movement of the print medium along a media advance path through the print zone, the cutting blade may cut in one or two linear directions, such as the X and Y directions.

DETAILED DESCRIPTION

FIG. 1 to 4provide an overview to illustrate a cutting arrangement using two cutter modules according to an example, in different perspective views.

In the illustrated example, the cutting arrangement comprises a first cutter module10and a second cutter module20, which are discussed in further detail below. The first and second cutter modules10,20are arranged on a shaft30extending in a direction perpendicular to a media advance direction of a printer which is illustrated by arrow A. The media advance direction A also is referred to as Y direction, and a carriage scanning direction, perpendicular to the Y direction, also is referred to as X direction. The direction of gravity, perpendicular to both the Y and X directions, may be designated as Z direction. The first cutter module10also can be designated as left-hand cutter module, and the second cutter module20also can be designated as right-hand cutter module, wherein left and right designates the position of the cutter module as seen from the front of the printer which, in this example, is the direction opposite to the media advance direction A.

The two cutter modules10,20are arranged on the shaft30to be independently slidable along the length of the shaft30, e.g., along the scanning direction, wherein sliding movement of the cutter modules10,20can be caused by respective first and second pulley drives12,22coupled to the first and second cutter modules10,20via positioners18,28. This allows selectively positioning the two cutter modules10,20at a right-hand edge and a left-hand edge of a cutting zone downstream of a print zone of the printer, for different cutting zones of varying width and position. In the illustrated example, a cutting zone of maximum width Pmax would extend about across the width of an output platen50, illustrated inFIG. 2. Each pulley drive12,22comprises a pulley belt14,24and pulley wheels16,26and drive units (not shown) for driving at least one of the pulley wheels16,26of each pulley drive. A drive unit may comprise e.g. an electric motor.

In the illustrated example, pulley drive22associated with the second or right-hand cutter module20extends across about 30% of the maximum cutting zone width Pmax, at the right-hand side of the cutting zone, and pulley drive12associated with the first or left-hand cutter module10extends across about 80-90% of the maximum cutting zone width Pmax, at the left-hand side of the cutting zone. The belts14,24of the first and second pulley drives12,22overlap and, for example, can be designed in such a way that the first and second cutter modules10,20can be positioned at any left-hand and right-hand margins of a print medium which the associate printer is able to print on in the print zone.

The first and second cutter modules10,20are removably coupled to the first and second pulley belts12,24by respective positioners18,28to be engaged with the cutter modules10,20. Accordingly, movement of either one of the belts14,24pulls the associated cutter module10,20along the shaft30to position the cutter modules10,20on two sides of an adjustable cutting zone, for example.

The shaft30is coupled to a drive motor40via a drive gear train42, including a number of gears, for transmitting rotation of the drive motor40to the shaft30. The drive motor40may be a BLDC motor or a stepping motor or another electric motor. The drive motor40may be supplied and driven via supply/drive lines44operatively coupled to a controller (not shown) of the printer, for example.

The cutter arrangement including the drive motor40may be mounted in a printer chassis (not shown) via a number of brackets and supports32,34,36,38,44.

FIG. 2illustrates an output platen50which may serve as support for a print medium which is transported through the printer and out of a print zone in the media advance direction A. the output platen50covers the pulley drives12,22and the positioners18,28to guide the print medium on a smooth surface of the output platen50. The cutter modules10,20will be arranged above the output platen.FIG. 2further shows a number of retractable ribs52which are provided for supporting the print medium to stay flat and even when transported in the media advance direction A. A print media advance system (not shown) may be provided to transport the print medium through the print zone and across the output platen50in a media advance direction A.

Further, a print head (not shown) may be arranged above the print zone upstream of the output platen50to deposit a printing fluid on the print medium within the print zone. The print head or several print heads may be carried by a printer carriage which may be slidable along a bar or a shaft (not shown) parallel to shaft30and extending in a direction perpendicular to the media advance direction A. The carriage may carry an array of print heads containing printing fluids, e.g. four, MCYK, ink inkjet print heads. The printing fluid may be dispensed from the print heads which may be any fluid that can be dispensed by an inkjet-type printer or other inkjet-type dispenser and may include inks, varnishes, and/or post or pre-treatment agents, for example. The carriage scans across the print medium in the print zone while the print heads are selectively fired to generate a printed plot.

FIGS. 3 and 4show further details of the drive gear train42, coupling the drive motor40to the shaft30, and of the coupling mechanism between the drive shaft30and the first and second cutter modules10,20.FIG. 3is a perspective view from a similar angle asFIG. 1, andFIG. 4is a perspective view from the opposite side ofFIG. 3. The same or corresponding components as in the previous figures are designated by the same reference numbers.

In the illustrated example, the drive gear train42comprises a number of spur gears which, in the example, provide three transmission stages to transmit rotation of a toothed output shaft41of the drive motor40to shaft30. The drive gear train42allows adjusting the rotation speed of the shaft30and transmits rotation of output shaft41in both a clockwise direction and a counterclockwise direction.

In the illustrated example, the shaft30has a polygonal cross-section, such as a hexagonal cross-section wherein other cross-sections, including a circular or noncircular, elliptic or a non-symmetrically shaped cross-section may be provided. The cutter modules10,20are coupled to the shaft30by respective transmission rings102,202. In the example, the transmission rings102,202engage with the outer periphery of the shaft30in a formfitting manner wherein, alternatively or additionally, a press fit or engagement by additional fixing elements, such as a screw, a bracket, adhesive or the like may be provided.

In the illustrated example, each cutter module10,20comprises an upper module half104,204and a lower module half106,206which clamp the respective transmission ring102,202. Handle-like extensions108,110,208,210are provided at the upper and lower module halves104,204to be grabbed and pressed against each other to pivot the upper and lower module halves108,110,208,210relative to each other to disengage the module halves from the transmission rings and unlatch the respective cutter modules10,20from the transmission rings102,202. Accordingly, each cutter module10,20can be replaced by pressing together the-handle-like extensions108,110,208,210, unlatching the cutter modules10,20from the transmission rings102,202and inserting another cutter module by the reverse operation.

In the example illustrated, each of the cutter modules10,20comprises an upper rotary cutting blade112,212and a lower rotary cutting blade14,24, which may be better recognized in the following drawings. The upper rotary cutting blade112,212is an example of an active cutting blade and the lower rotary cutting blade14,24is an example of a passive cutting blade. The respective upper rotary cutting blades112,212are movable cutting blades which are driven to rotate by rotation of the shaft30, via a respective transmission group provided in the respective cutter module10,20. Each transmission group may have an adjustable transmission ratio. In the example, the lower rotary cutting blade14,24may be in contact with the upper rotary cutting blade112,212to be friction-driven by the upper rotary cutting blade and to cut a print medium there between.

In another example, instead of providing a lower rotary cutting blade, a lower stationery blade may be provided, such as a knife like linear blade, which interacts with the upper rotary cutting blade112,212to cut a print medium there between. The lower stationery blade is another example of a passive cutting blade. In another example, the upper rotary cutting blade112,212may interact with a counter surface, instead of a lower cutting blade, to cut the print medium transported across the counter surface.

In the examples, each of the cutter modules10,20comprises a gap116,216to guide a print medium there between and towards the associated cutting blades112,114,212,214.

When cutting thin media of low rigidity, the material could cause a jam in the gap116and may suffer scratches if the media is not transported sufficiently flat and tensioned relative to the cutter modules. This is particularly noticeable if the media material expands with ink deposition and increased humidity. Therefore, the cutter modules include a traction mechanism to pinch a medium to be cut in the gap area adjacent to the upper rotary cutting blade and the lower cutting blade. For example, by providing a contact surface associated with and adjacent the upper rotary cutting blade and a counter surface associated with and adjacent the lower rotary cutting blade, the cutter module has traction capacity wherein the medium to be cut is pinched between the contact surface and the counter surface. Additionally this media expansion could also affect the shape of the media in the print zone. If the media expansion is not absorbed by the cutter modules, a bubble of media may appear under the pen carriage and the printheads may scratch the upper surface of the printing media.

FIGS. 5A, 5B, 6A, 6B, 7A, and 7Bshow different views of a cutter module according to an example, or parts thereof, to illustrate an example of the traction mechanism. Reference is made to the above description ofFIG. 1 to 4wherein the same reference numbers designate same or corresponding features. The drawings show a left-hand cutter module10, with the right hand cutter module being configured in a similar way. The right-hand module20and the left-hand module10may be mirror versions of each other or may include variations.

The cutter module10shown in the drawings comprises upper and lower module halves104,106, the upper module half104rotatably supporting the upper rotary cutting blade112(best seen inFIGS. 6B and 7B) on an associated shaft126and the lower module half106rotatably supporting the lower rotary cutting blade114on an associated shaft128, the cutting blades located on opposite sides of the gap116. In an example, the upper cutting blade112may be an active driven cutting blade and the lower cutting blade114may be a passive cutting blade because it may not be actively driven by an associated drive mechanism in contrast with the upper cutting blade112.

Adjacent to and coaxial with the upper rotary cutting blade114, a ring-shaped disc carrying an O ring130is provided. The peripheral surface of the disk and/or of the O ring130features a contact surface132. Adjacent to the lower rotary cutting blade116a counter body134is provided wherein the counter body has a cylindrical outer face which features a counter surface136. The contact surface132and the counter surface136can be used to pinch a medium to be cut there between so that the cutter module10, in addition to cutting the medium, has traction capacity and can hold and pull the medium which is trapped between the contact surface2and the counter surface136. Accordingly, the medium can be transported by the cutter module10during cutting. Additionally, if a right hand cutter module and a left-hand cutter module having the same type of traction capacity are provided, the medium can be tensioned between the two cutter modules to obtain a clean cut.

One or both of the contact surface132and the counter surface136may be made of or provided with an elastomeric surface. For example, an elastomeric O ring130may be arranged adjacent to the upper rotary cutting blade to provide an elastomeric contact surface132. Elastomeric surface(s) enhance friction between the contact and counter surfaces132,136and the medium to be cut.

The counter surface136provided at the lower rotary cutting blade114may be biased against the contact surface. For example, the counter body134may be shaped as a hollow cylinder or a hollow cup, wherein an interior face of the hollow cylinder is supported on a shaft128of the passive cutting blade114via a spring140, illustrated inFIG. 5B, in which the counter body134is not illustrated. For example, if the counter body134is shaped as a hollow cylindrical cup, the cylinder axis is extending perpendicularly to the shaft128of the lower cutting blade114, and the peripheral surface of the cylindrical cup, forming the counter surface136, is pushed upwards towards the contact surface132associated with the upper rotary cutting blade112, by the spring140generating a biasing force between the shaft128and the interior face of the cylindrical cup. The spring140may comprise a torsion spring. Biasing the counter surface136against the contact surface132increases traction force and provides an approximately constant force between the contact and counter surfaces132,136, independent of wear of mechanical parts of the cutter modules10,20and of the thickness of the medium to be cut. Furthermore, biasing the counter surface136provides the cutter with the ability to cut while applying a tension and traction force on media of several thicknesses.

In an alternative example, not shown in the drawings, the passive or lower cutting blade may be a linear cutting blade, associated with a counter body which is arranged adjacent to the lower cutting blade, the counter body having a plane outer face providing a counter surface. The counter body may include a spring or other device to bias the counter surface against the contact surface132associated with the upper rotary cutting blade112. As in the previous example, the counter surface may feature an elastomeric surface to enhance friction between the counter surface and a medium to be cut to reliably pinch and grab the medium between the counter surface and the contact surface132.

FIG. 7Aadditionally illustrates a transmission group118which is provided between the shaft30and the upper rotary cutting blade112to drive the upper rotary cutting blade112by rotation of the shaft30. The transmission group118comprises a number of gears120,122,124wherein a first gear120comprises a cylindrical body which engages with the surface of the transmission ring102to transmit rotation of the shaft30the first gear120. The first gear120meshes with a second gear122which in turn meshes with a third gear124. The third gear124is supported on a common rotary shaft126which also carries the upper rotary cutting blade112. Accordingly, the upper rotary cutting blade112and its associated contact surface132are driven by rotation of the shaft30via the transmission group118. The lower rotary cutting blade114is supported by its associated shaft128supported in the lower module half106. The lower rotary cutting blade114and its associated contact surface136may be driven by the upper rotary cutting blade112by friction contact between the two blades11,114. Drive of the upper active rotary cutting blade by rotation of the shaft is just an example and other ways of driving the rotary cutting blade(s) are possible.

FIG. 8shows a flow diagram of a media cutting process according to an example. The process may be performed in a printer, such as an inkjet printer, including a cutter arrangement having two cutter modules10,20. The process comprises engaging the cutter modules10,20and the shaft, at block60, and moving the cutter modules10,20along the shaft30to desired lateral positions at the two sides of printing and cutting zones, at block62. The cutter modules10,20can be arranged at a distance corresponding to a to-be-cut width of a print medium. The print medium then is advanced towards a print zone of the printer, at block64, with a leading edge of the print medium crossing the print zone in the media advance direction A. The print medium (not shown in the drawings) can be a print medium, such as a single sheet or a continuous web of print medium fed to the print zone from an input tray, a drawer or roll of paper, for example. The medium may be paper or a foil, for example. The print medium can be fed by media feed rollers which are arranged downstream and/or upstream of the print zone, by a belt or a number of belts and/or by rollers integrated into the print platen, for example.

Once the print medium has arrived at the print zone, the printer can start printing swaths of a print fluid, such as ink, and advancing the medium through the print zone, at block66. At block68it is checked, whether the leading edge of the print medium has arrived at the cutter modules10,20. If no, the printer continues to print swaths of the print fluid and advance the print medium in the media advance direction, at block66. If the leading edge of the print medium has arrived at the cutter modules, the leading edge of the print medium can be engaged by the cutter modules10,20at two opposite sides of the print zone, at block70, and the process can continue with printing on and cutting the print medium while advancing the printing medium, at block72.

The leading edge of the print medium can enter the gaps116,216, near side edges of the print medium, to come into contact with the cutting blades112,114,212,214. At the same time, the print medium also will be engaged between the contact surface132associated with the upper rotary cutting blade112and the counter surface136associated with the lower rotary cutting blade114. At this point in the process, the cutting blades start cutting into the print medium. During the cutting process, the upper cutting blade112is rotated by rotation of the shaft30and rotation is transmitted to the lower cutting blade114by friction between the two cutting blades112,114. Accordingly, also the contact surface132and the counter surface136rotate together with their associated cutting blades112,114so that the print medium is pinched and transported between the two surfaces132,136.

If the circumferential speed of the rotary cutting blades112,114,212,214is higher than the media advance speed, rotation of the rotary cutting blades112,114,212,214and the respective contact and counter surfaces132,136can create a tensioning effect which pulls the print medium in the media advance direction so that the print medium is held flat and tensioned, improving the cutting performance. Concurrent with the cutting operation64, printing on the print medium may be performed.

The cutting blades and the associated contact and counter surfaces132,136may be aligned to a direction parallel or substantially parallel to the media advance direction A. The cutting blades and the associated contact and counter surfaces132,136alternatively may be aligned to a direction which includes a small angle with the media advance direction A, such as an angle of about 0.5° to 5° to the media advance direction A. Accordingly, when the cutting blades rotate, due to their slightly oblique arrangement, the cutter modules pull the medium in the media advance direction A but also apply a small pulling component towards the outside of the plot in the scanning direction X. The cutting blades and the associated contact and counter surfaces132,136are arranged in such a manner that the left-hand cutter module10pulls to the left and the right hand cutter module20pulls to the right, as seen from the front of the printer. This tensions the medium to be cut and removes bubbles of the medium between both cutter modules.

The print medium continues to be advanced in the media advance direction A, with continued printing and cutting operations, as long as the printing process is not completed. Printing on the print medium in the print zone and cutting the two opposite side edges of the print medium in the media advance direction can be performed simultaneously in what may be considered a single operation. It also can be performed intermittently.

At block74, it is checked whether printing is completed. If yes, the advance of the print medium can be interrupted and a trailing edge of the print medium can be cut in a direction traversing the media advance, i.e. in the X direction, at block76.

Advance of the print medium then can continue by the engagement of the print medium between the contact surface132and the counter surface136, which continue to be driven together with the upper and lower rotary cutting blades112,114, at block78. This is possible in spite of the print medium having been cut in the X direction so that the print media advance system of the printer may no longer be able to engage with and advance the print medium. The intrinsic traction capacity of the cutter modules can be used to pull the last portion of the print medium and to finalize cutting in the Y direction as the print medium is transported by the traction force of the contact and counter surfaces132,136.

Media advance may be stopped and cutting may be interrupted, at76, for example, when a defined distance between the cutting blades112,114and the trailing edge of the printed product is reached, such as about 1 or 2 cm away from the trailing edge. Then the trailing edge can be cut and the remaining media transport is effected by the traction capacity of the contact and counter surfaces, finalizing the cutting operation. In an alternative example, when a defined distance between the cutting blades112,114and the trailing edge of the printed product is reached, the medium may be moved back by a defined distance to cut the trailing edge, and then the remaining media transport is effected by the traction capacity of the contact and counter surfaces, finalizing the cutting operation. Either way, the process avoids any cutting marks or imprints generated by the cutter modules in the side margins of the printed product. The process also may avoid generating a strip of waste medium between subsequent prints.

The traction capacity of the cutter modules described herein improves reliability in cutting thin media of low rigidity and additionally improves the ability to cut thick and stiff media. It eliminates the risk of jams and scratches.

Drive of the print media advance system (not shown), the shaft30and pulley drives12,22of the cutter modules10,20as well as other entities of the printer and an associated cutting equipment may be controlled by a controller (not shown). The controller can be a microcontroller, ASIC, or other control device, including control devices operating based on hardware or a combination of hardware and software. It can include an integrated memory or communicate with an external memory or both. The same controller or separate controllers may be provided for controlling carriage movement, media advance and the rotary actuator. Different parts of the controller may be located internally or externally to a printer or separate cutting device, in a concentrated or distributed environment.