Printer for cutting media and method thereof

Abstract: A method and device for directly positioning and holding media against an output platen while a cutter traverses across a media path. A cutter assembly is mounted on an arm which periodically passes over the media, and includes a cutter blade (108) and at least one media restraint wheel (118) which presses the media against the output platen. The media restraint wheel (118) is located in close proximity to the cutter blade (108), such that the media restraint wheel (118) is upstream from the cutter blade (108) and also is laterally displaced from the cutter blade (108) to achieve direct engagement of the media by the media restraint wheel (118) prior to cutting the media. The media restraint wheel (118) includes a soft rubber-like tyre which rolls along a top surface of the media while rotating freely on an vertically adjustable axle (126), in order to accommodate both thick and thin media, without the need for a separate media hold-down device. A biasing spring (120) presses downwardly against the axle (126) to assure secure holding of the media against the output platen. Preferably, at least one opposing wheel (114) upstream from the cutter blade (108) is provided on the cutter assembly for rolling engagement with the output platen to assure proper positioning of the cutter blade (108).

Description: Printers often provide a cutter which can be used to cut the media without having to remove the media from the printer. This is particularly desirable in large format printers which typically have rollfeed media. Conventional cutters have been mounted on large format printers for either automated or manual actuation to pass a cutting blade across the media after a printing operation is completed. Some rotary cutting blades have been used in conjunction with fixed linear blades on the printer, and various techniques have been used to hold the media in position during a cutting operation. However, such prior cutters have either been overly expensive and complicated, or have not provided precise and reliable cutting of the media. US Patent No. 4,701,063, which is the closest prior art document and has been used for the delineation in two-part from of Claims 1 and 12, discloses a printing mechanism provided with a rotary cutter mounted on a printing trolley to enable a recording medium to be cut as the printing trolley moves during a printing operation. For retention of the recording medium, the control device acts independently of the rotary cutter upon retention rollers which are arranged on both sides of the rotary cutter. Accordingly there is a need for a simplified cutter that provides automated cutting using a self-contained cutter assembly which employs rotary blades and rotating wheels to traverse across printed media while providing a satisfactory cutting operation. The present invention seeks to provide a method and device for directly positioning and holding media against an output platen while a cutter traverses across a media path. According to an aspect of the present invention there is provided a printer for cutting through media in a cutting zone located downstream from a printing zone, comprising: a printer frame having an output platen located in a cutting zone downstream from a printing zone; a cutter assembly mounted for movement across said cutting zone, and carrying at least one cutting element; wherein a media restraint wheel on said cutter assembly and laterally displaced from said cutting element achieves engagement of the media by the restraint wheel to press the media against said output platen prior to cutting the media by said at least one cutting element, and mounting said media restraining wheel with a first angular inclination with respect to the direction of movement of said cutter assembly. Preferably, the media restraint wheel urges the media against a top surface of said output platen, and further including an opposing wheel on said cutter assembly which engages a bottom surface of said output platen. In a preferred embodiment, the restraint wheel and said opposing wheel are located approximately the same distance downstream from said printing zone. More preferably, the media restraint wheel is slidable mounted for vertical adjustability depending on the thickness of the media. In a further preferred embodiment, said cutter assembly further includes spring means for biasing said restraint wheel downwardly against the media. Typically, said one or more cutter elements include a first rotary cutter located generally above the media and a second rotary cutter located generally below the media. Preferably, the rotary cutters are mounted on said cutter assembly with a second and third angular inclinations with respect to said direction of movement of said cutter assembly. More preferably the rotary cutters are mounted at a fixed distance apart from each other, such that their peripheral cutting edges overlap a predetermined distance. In an improved embodiment, the first and second rotary cutter (108, 110) have a diameter of less than 3 cm. and said restraint wheel (118) has a diameter of less than 2 cm. Typically, said first and second inclinations is comprised between, or equivalent to, 2 and 4 degrees. Viewing another aspect of the present invention, there is also provided a method of cutting rollfeed media in a printer, comprising the steps of: passing the media through a print zone in a forward direction along a media path to create printed media; maintaining the printed media in a stationary position in a cutting zone located downstream from the print zone; rolling a tyre in rolling contact with the printed media and across a surface of the printed media to hold the printed media against an output platen in the printer; wherein said tyre is mounted with an agular inclination with respect to the direction of the force applied to hold said tyre against said printed media and passing a rotary cutting blade along a cutting line on the media to cut a section of printed media, held against said output platen by said tyre during said rolling step. The present invention will be described further by way of example only, with reference to an embodiment thereof as illustrated in the accompanying drawings, in which: Fig. 1 is a fragmented pictorial view showing a printer which incorporates the present invention with an active deflector guide; Fig. 2 shows a front pictorial view of a rollfeed printer which incorporates the present invention, with a user manually feeding a leading edge of rollfeed media past two deflector guides; Fig. 3 shows the pictorial view of Fig. 1 with a leading edge of media in position for being pulled into a media path, upon activation of a control button on an active deflector guide by a user without having to remove the right hand from holding the media against an input platen; Fig. 4 is a schematic view partially in cross-section showing a media path for passing rollfeed media through the printer of Figs. 1-3; Fig. 5 is a fragmented perspective view showing a second embodiment of a cutter assembly which has been moved by a motorized printer carriage from right to left to cut off a section of media which has passed through a print zone of the printer; Fig. 6 is a right end view of a guide platen for the cutter assembly as shown in Fig. 5; Fig. 7 is a partial sectional view showing the guide platen of Fig. 6 integrated with the input and out paths for media passing through the printer; Fig. 8 is an enlarged fragmented perspective view showing the second embodiment of the cutter assembly of Fig. 5 slidably mounted on a carriage support rod; Fig. 9 is a perspective view of the cutter assembly of Fig. 5; Fig. 10 is an enlarged internal view of a cutter housing without any wheels or cutting blades; Fig. 11 shows the internal view of the cutter housing of Fig. 10 with one rotary cutting blade, three wheels and a downward biasing spring mounted therein; Fig. 12 shows an exploded view of Fig. 11 with a head cover and mounting screws included; Fig. 13 is a partial sectional view of a combined drive wheel/rotary cutter; Fig. 14 is an exploded view showing how the components of Fig. 12 are attached with a second rotary cutter to one end of a cutter arm; Fig. 15A is a schematic diagram showing preferred angles of inclination for two rotary cutting blades; Fig. 15B is a schematic diagram showing a preferred range of angles of inclination for a media press wheel; and Fig. 16 is a graph showing preferred traversing speeds for the cutter assembly during a cutting operation. Referring now to Figs. 1-4 in the drawings, the invention is applicable to a printer such as a large format inkjet printer 21 into which printing media such as sheet 22 may be fed along a media path leading to a print zone (not shown). A front input platen 23 for the printing media has on one side an alignment of reference marks 24 which may be formed by small holes, for enabling a corresponding side edge 25 of the printing media to be aligned at the moment when it is introduced into the front portion of the printer. The manual feeding operation for loading the printing media into the machine therefore involves the alignment of the edge 25 with the reference line (See Fig. 2). As part of the media feeding procedures, the operator must ensure that a front leading edge of the printing media is suitably positioned without substantial deviation. This entire operation takes place with the printing-media entrainment rollers (typically a pick-roller and opposing pinch rollers) stationary to allow the operator to manipulate the printing media properly as it enters the machine. Only when the operator has ensured that the printing media is suitably positioned at the input of the machine does he operate a control button for activating the drive motor of the printing media entrainment rollers. In the embodiment shown in the drawings, a push-button 26 is incorporated in an active deflector guide 27 which acts as a deflector for both the input and output of the printing media. This arrangement considerably facilitates the manual operation of the activation push-button. However, the push-button may be disposed in any other position on the machine, for example, on the instrument panel 29 or in another suitable place, as appropriate for the general configuration of the machine or for the way in which it operates. As can be seen from Figs. 2 and 4, the rollfeed printing media 32 can proceed from a roll 20 past a deflector guide 27 and media shield 31 along an input platen 23 to an entry slot between a main roller 33 and pinch wheel 35 for passing the media past a print zone (not shown) to an output path 34. The space 28 between or adjacent to the deflector guides (active 27 and passive 37) is available for placing one or both hands directly on top of the media to guide its leading edge up to the input slot. Even when the printer top 39 is closed, it is still possible see the media through a transparent window 41 on the front of the printer top. Also, one of the manual access spaces 28 on the right side of the input platen is very close to a pinch wheel release lever 43 for moving the pinch wheels between an engagement and disengagement position. Figs. 5, 8 and 9 show the details of the fully operating cutter assembly which is retrieved from a parking position by the carriage in a manner previously implemented in the previous DesignJet large format printers. Figs. 6-7 show the details of the media shield 31, including an output platen 74, central and bottom mounting screw holes 76, 78, rear mounting slot 80 for hanging on right and left printer frame pins (not shown), and input slot guide 82 which aligns with rear edge 58 to provide a continuous guide into the pinch wheels/pick roller portion of the media path. The output path may include output rollers 84, star wheels 86, and a flexible Mylar paper separator 88. Figs. 10-14 show the details of the mounting of cutter blades and wheels within the casing and housing components of the cutter assembly. Figs. 15A and 15B show the specific angular inclinations of the cutter blades and wheels. In that regard, the amount of overlap between the two rotary cutter blades determines the angle of deflection of the cut media passing from the cutter assembly, which in the preferred embodiment is approximately 13 degrees. Fig. 16 shows that a preferred initial translational speed of the cutter assembly at the time of first encountering the media to be cut is 5 ips, while thereafter the preferred speed through the rest of the cutting operation is 30 ips. The cutter assembly is mounted on an arm 100 which periodically passes over the media. It will be understood from the drawings that the cutter arm 100 rides on the same slider bar as the carriage through bushing 102, and carries cutter components lower driven tyre 104 having a central wheel 106 and concentric driven rotary blade 108, as well as upper rotary blade 110 which is biased by spring 112 against the driven blade. Preferably, an opposing additional positional tyre 114 upstream from the cutter blade is provided which is periodically engaged by the underside 116 of the output plate. The rolling engagement with the output platen allow to properly positioning the cutter. Such underside 116 plate is textured to assure maintenance of the proper frictional contact with the drive tyre 104. A media restraint wheel is provided to press the media against the output platen. The media restraint wheel is located in close proximity to the rotary blades, such that the media restraint wheel is upstream from the cutter blades and also is laterally displaced from the rotary blade to achieve engagement of the media by the media restraint wheel prior to cutting the media. The media restraint wheel includes a soft rubber-like tyre 118 which rolls along a top surface of the media while rotating freely on an axle slidably mounted in two spaced apart vertical slots. This provides vertical adjustability in order to accommodate both thick and thin media as well as changes in the platen itself , without the need for a separate media hold-down device. The tyre 118, located in an upper position, is biased by biasing spring 120 which is mounted along with the other aforesaid components in housing 122. The spring 120 presses downwardly against the axle to assure secure holding of the media against the output platen as well as to assure proper vertical positioning of the cutter assembly. A side plate 124 and related mounting screws 126 provide attachment and bearing functions for the various components. An additional biasing spring 128 acts against the second rotary blade 130 by virtue of additional mounting screws 132.

Claims: A printer for cutting through media (22) in a cutting zone located downstream from a printing zone, comprising: a printer frame having an output platen (74) located in a cutting zone downstream from a printing zone; a cutter assembly mounted for movement across said cutting zone, and carrying at least one cutting element (108); and, a media restraint wheel (118) on said cutter assembly and laterally displaced from said cutting element (108) to achieve engagement of the media by the restraint wheel (118) to press the media against said output platen (74) prior to cutting the media by said at least one cutting element (108), characterised by mounting said media restraint wheel (118) with a first angular inclination (γ) with respect to the direction of movement of said cutter assembly. The printer of claim 1 wherein said media restraint wheel (118) urges the media against a top surface of said output platen (74), and further including an opposing wheel (104) on said cutter assembly which engages a bottom surface of said output platen (74). The printer of claim 2 wherein said restraint wheel (118) and said opposing wheel (104) are located approximately the same distance downstream from said printing zone. The printer of any one of the preceding claims, wherein said media restraint wheel (118) is slidable mounted for vertical adjustability depending on the thickness of the media. The printer of claim 4, wherein said cutter assembly further includes spring means (120) for biasing said restraint wheel (118) downwardly against the media. The printer of any one of the preceding claims wherein said one or more cutter elements include a first rotary cutter (110) located generally above the media and a second rotary cutter (108) located generally below the media. The printer of claim 6, wherein said first and second rotary cutters (108, 110) are mounted on said cutter assembly with a second and a third angular (α, β) with respect to said direction of movement of said cutter assembly. The printer of claim 7, wherein said first and second rotary cutters (108, 110) are spaced apart such that their peripheral cutting edges overlap a predetermined distance. The printer of any one of claims 6 to 8, wherein said first and second rotary cutters (108, 110) have a diameter of less than 3 cm. The printer of any of the preceding claims, wherein said restraint wheel (118) has a diameter of less than 2 cm. The printer of any preceding claims, wherein said first angular inclination (γ) is comprised between, or equivalent to, 2 and 4 degrees. A method of cutting rollfeed media in a printer, comprising the steps of: passing the media through a print zone in a forward direction along a media path to create printed media; maintaining the printed media in a stationary position in a cutting zone located downstream from the print zone; rolling a tyre (118) in rolling contact with the printed media and across a surface of the printed media to hold the printed media against an output platen in the printer; wherein said tyre (118) is mounted with an angular inclination (γ) with respect to the direction of the force applied to hold said tyre (118) against said printed media and passing a rotary cutting blade (108, 110) along a cutting line on the media to cut a section of printed media, held, against said output platen, by said tyre (118) during said rolling step. a. The method of claim 12, wherein said rolling step is applied to a surface of the printed media upstream from the cutting line of said passing step.

Inventors: HINOJOSA ANTONIO, HINOJOSA, ANTONIO
Applicants: HEWLETT PACKARD CO, HEWLETT-PACKARD COMPANY
Application year: 1998
Main classification: B41J11
IPC codes: B41J11, B26D1