Abstract:
A print media feeder system to automatically change the supply of a printing medium in a printer between a feeder mode of medium in continuous band form and a feeder mode of medium in cut sheet form, comprising a pair of rollers arranged at a point along a first movement path of a first printing medium in continuous band form, said point being loacated between the input for said first medium and the main roller pulling the same and which rollers can be made to cooperate to, selectively, pull said first medium in one or the other direction along said first movement path; valve means for the printing medium arranged to cooperate with said main pulling roller for the purpose of allowing the passage, along the length of said first movement path, of said first medium towards or from a printing area, and to prevent passage of a second printing medium in cut sheet form from said printing area, around said main roller and along said first movement path, which valve means divert said second printing medium in cut sheet form along the length of a second movement path, differing from said first path.

Description:
FIELD OF THE INVENTION 
     This invention relates, in general, to print media feed apparatus for hard copy printing devices capable of operating with printing media in continuous band or sheet form and, more particularly, to large format ink jet printers, plotters and the like with the ability to, interchangeably, handle a continuous media in roll form and/or cut sheets. 
     BACKGROUND OF THE INVENTION 
     An ink jet printer mechanism is a non-impact printing device which forms characters and other images ejecting ink droplets, in a controllable manner, from a print head. The ink jet mechanisms can be used in different devices, such as printers, plotters, facsimile machines, copiers and the like. For the sake of convenience reference shall hereinafter be made solely to large format ink jet printers or plotters, to illustrate the concepts of the present invention. 
     The printhead of a machine of the kind mentioned ejects ink through multiple nozzles as minuscule droplets, which “fly” over a short space and strike a printing media. Different nozzles are used for different colours. Ink jet printers usually print within a range of 180 to 2400 or more dots per inch. The ink thus deposited on the media is immediately dried after being deposited to form the desired printed images. 
     There are several types of ink jet printheads, for example, thermal print heads and piezoelectric ones. By way of example, in a thermal ink jet printhead, the ink droplets are ejected from individual nozzles by localized heating. Each of the nozzles has a small heating element. An electric current is made to pass through the element to heat it. This causes a tiny volume of ink to be heated by the heating element and vaporized instantaneously. On vaporization the ink is ejected through the nozzle. An exciter circuit is connected to individual heating elements to supply energy impulses and, in this way, to deposit in a controlled way droplets proceeding from associated individual nozzles onto the media. These exciter circuits respond to character generators or other imaging circuits to activate selected nozzles of the printhead to form the desired images on the media. 
     The ink nozzles customarily form part of an ink cartridge, disposable or otherwise, and the printhead of a printer of the kind to which the invention refers can have cartridges mounted for different ink colours, for example, cyan, magenta, yellow and black. These are arranged in the carriage in such a way that their nozzle sections are to be found very close to the surface of the support platen of the media, but separated therefrom, for the purpose of allowing the passage of said media between them. The carriage moves the printhead back and forth through the printing zone in one direction, called the scan direction, the location of the carriage in the printing zone being constantly controlled thanks to codifying means which control an actuating motor, for example a stepping motor. 
     In machines of this type there is generally used, as media, a band of paper of large width, for example D and E size, arranged in rolls of up to 90 m. in length. A 90 m. roll of E size paper can weigh almost 8 kg., so precautions should be taken at the time of handling it. 
     Such handling is even more difficult if we consider that the face of the media band on which the printing is performed is the external face and that a large part of the media used in a machine of the kind to which the invention refers have a coated surface which is sensitive to contact with the operator&#39;s hands, such that the operator should as much as possible avoid touching said printing surface during operation while, at the same time, keeping it clean and away from objects that could harm or scratch the media surface. 
     Moreover, for certain printing tasks the operator may have to utilize media in the form of large cut sheets, for example in A, B, C, D and E formats, as well as in formats utilized in Architecture. Such pre-cut sheets can easily spoil during handling, especially the larger sized ones. Care should be taken when removing the media from the packet and during its insertion and adjustment in the printer and, furthermore, care should be taken to touch the media only at the edges, to avoid harming or soiling the area on which the printing has to take place. 
     Once the printing task concludes, the machine automatically cuts the media (this does not occur in the case of printing on individual sheets) and the media, in one or the other case, is allowed to drop on to the output tray, with the possibility of the ink still not having dried completely with the resulting risks this entails, i.e., that the printed work may be spoilt during initial handling of the media. 
     In the prior art printing machines of different types are already known (impact or ink jet, for example) which are capable of printing both on continuous media and on cut sheets. A known machine of this type makes use of a “parking” facility of the continuous paper while operating with cut sheets fed manually. 
     For example, from U.S. Pat. No. 5,544,966 a printer is known which, provided with at least one tractor for continuous paper, allows the use of cut sheets to print while the continuous paper is “parked” outside the printing area. This machine achieves this interchangeable feeding by the provision of, at least, two different pathways for paper input (continuous and cut sheets), a third pathway being foreseeable for the input of continuous paper, likewise with the intervention of a tractor (the one cited or another additional one) for paper. 
     In the first place the printer to which said document of the prior art refers, is of small format and provided with tractors for the input of paper, which can be fed into it in continuous band, folded zig-zag, with the usual perforations in the margins or in the form of loose sheets, of small format. 
     In the second place, in said printer of the prior art is necessary to change the turning direction of the main roller to take the continuous medium towards a parking position, beyond the printing area and out of contact with said main roller prior to being able to feed cut sheets. 
     Large-format printers are also known, to allow parking of a print medium supplied starting from a roll and feeding in, in its place, a cut sheet to perform a printing operation on it. These prior art printers have two superimposed openings for input of the printing medium: one for the supply starting from a roll and another for the supply as cut sheet. However, the said two superimposed openings give way to a single advance path of the printer medium. 
     In machines of this type, when a user wishes to perform a printing task on a cut sheet in a printer loaded with continuous medium, the printer has to be requested, in the first place and by pressing a control panel button, to withdraw the continuous medium from the printing area, making it recede separating it from the main feeder roller and parking it, by a deviator which completely withdraws it from the main advance roller. In the second place, the user has to manually insert the medium in cut sheet form into the suitable opening, operation of which is bothersome, since the manipulation of said cut sheet is difficult, owing to its extreme width and, in particular, because of the close arrangement of said two input openings (which are, moreover, hidden from the operator&#39;s view), the most likely result being that the cut sheet will be fed into the wrong opening, already occupied by the parked continuous medium. Finally, by means of another push-button in the control panel, the user has to make the machine load the paper in sheet form until the printing area. 
     Moreover, the input path of the means in sheet form is practically mutual with that of feed in of the medium in cut sheet form and it is not possible to supply said cut sheet simultaneously with removal of the medium fed in starting from a roll. 
     SUMMARY OF THE INVENTION 
     A print media feeder system to automatically change the supply of a printing medium in a printer between a feeder mode of medium in continuous band form and a feeder mode of medium in cut sheet form, comprising a pair of rollers arranged at a point along a first movement path of a first printing medium in continuous band form, said point being loacated between the input for said first medium and the main roller pulling the same and which rollers can be made to cooperate to, selectively, pull said first medium in one or the other direction along said first movement path; valve means for the printing medium arranged to cooperate with said main pulling roller for the purpose of allowing the passage, along the length of said first movement path, of said first medium towards or from a printing area, and to prevent passage of a second printing medium in cut sheet form from said printing area, around said main roller and along said first movement path, which valve means divert said second printing medium in cut sheet form along the length of a second movement path, differing from said first path. 
     Thus embodiments of the present invention provide two different input paths for the medium: one for continuous medium and the other for medium in cut sheet form. Where the path meet, there is provided a medium valve. 
     In accordance with embodiments of the invention, an operator can load continuous media into the machine starting from a roll of the same and perform a printing task; afterwards he can load a cut sheet without touching the media roll, perform another printing thereon and, after withdrawing said cut sheet, he can once again operate with continuous media from the roll without at any time touching the media. 
     To achieve this, in the advance path of the medium, there is provided an auxiliary driver axis provided with, at least, one roller and arranged transversally respecting the direction of advance of the medium, between a first input roller intended to guide the medium and the main roller feeding in the same, whose auxiliary driven axis can adopt a first position, in which it is to be found separated from the path of the medium fed in starting from a roll, and a second position in which it is applied with said medium, which is grasped between said at least one roller of the auxiliary driven axis and by at least one roller assembled in a supporting axis arranged to turn freely (whose geometrical axis is parallel to the geometrical axis of said auxiliary tractoraxis) such that said continuous medium can be made to advance and/or retrocede along said advance path. 
     In its turn, said auxiliary axis, when in said second position of application with the continuous means, can adopt a first condition, in which it turns freely, allowing advance of the medium removed from said input roll until the medium achieves a “READY” position (prepared for printing) in the printing area of the machine and while a printing operation is performed on it, and a second condition, in which it is actuated in a first turning direction to make said continuous medium recede, removing it from the printing area and from the main pulling roller and taking it to a “STAND BY” or “parking” position, during which the printer can be carrying out a printing operation on a cut sheet, or in which it is actuated in the opposite direction to said first turning direction, to once again feed in said continuous medium that was parked, until taking it to the ready to print position, in said printing area. 
     Furthermore, the operator can easily insert a media in the form of a cut sheet into the machine and, before carrying out a printing task thereon, can easily align said sheet thanks to the retention which, owing to a vacuum acting through openings provided in the printing platen, allows easy handling of the sheet to achieve an exact positioning of the same, while said sheet is lightly retained by the mentioned vacuum. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In what follows a preferred embodiment of the invention will be described, solely by way of example and making reference to the attached drawings, in which: 
     FIG. 1 is a perspective view of a large format ink jet printer, which incorporates the invention; 
     FIG. 2 is a perspective detailed view of the paper pulling mechanism and of the area of the printing platen of a printer such as that of FIG. 1, on a first operative stage; 
     FIG. 3 is a view, similar to that of FIG. 2, on a second operative stage of the printer; 
     FIG. 4 is a schematic end view, showing the feeder mechanism of a printer in accordance with the invention, on a first operating stage corresponding to that represented in FIG. 2; 
     FIG. 5 is a view similar to that of FIG. 4, with parts withdrawn for greater clarity, but on a second operating stage corresponding to that shown in FIG. 3; and 
     FIGS. 6A-6D are schematic views in cross section, taken along the line A-B of FIG. 3, representing different phases of operation of the printer according to the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In FIG. 1 an ink jet printer is illustrated generally, of the type mentioned in the preamble of this specification, in this case a large format high yield plotter, including a central platen  12  intended to support the medium during printing and above which, there moves, the length of at least one guide bar, a carriage carrying the printer head (hidden in this case by the cover  11 ), intended to move, from one end to the other of the same, thus defining a printing area of the machine. Occasionally the carriage, carrying the printer head, moves towards one end of the machine, for example that designated with  14 , in which a service station is located, to carry out cleaning of the nozzles and/or priming of the ink. 
     A feeder mechanism (of which the input guide roller  20  of this figure forms part) is utilised to achieve advance of the medium along a first feeder path through the machine, said feeder mechanism being comprised by a set of shafts and rollers which shall be described hereinafter. This feeder mechanism allows, in general, removal of the medium from the storage roll  16 , causing it to pass through the printer, above the platen  12 , where the printing operation is performed, and causing it to come out of the machine, after cutting it, to fall into a collector tray  18 . 
     Said roller  20 , assembled rotatively at its ends on both sides of the printer frame, can turn freely and facilitates input of the printing medium, guiding it in its entry into the machine and at the same time eliminating friction to which said medium would otherwise be subject and which could damage its surface on which it has to be printed. By way of example, said roller  20  can have a longitudinally slotted or striated surface to facilitate guiding the paper. 
     The printer  10  has a predefined printing area which coincides, at least partially, with a part of the feeder path of the medium, such that this is fed in through the printer area. One illustrative printer area is defined as that within which each one of the multiple nozzles of the printer head can print the entire width of the medium. 
     We shall make reference now to FIGS. 2 to  5  of the drawings, in which the spatial relationship is shown, of the components of the system for feeding the printing medium into the machine, there being represented in FIGS. 2 and 4 the printer with a swinging chassis  21  in a raised condition and, in FIGS. 3 and 5 in a lowered condition. In said figures there is indicated with  12  the central platen intended to support said medium during the printing operation, representing, with  34  and  35 , respectively, the front and rear platens for supporting the medium while coming out of the machine. With  20  the roller is indicated, intended to guide the medium on entering the printer from its storage roll  16  (see FIG.  1 ). Above said roll  20  a swinging chassis  21  is provided, provided with flaps  22  to be moved manually by the operator between two positions: one above (FIGS. 2 and 4) in which it is to be found separated from said roller  20 , and a lower one (FIGS.  3  and  5 ), in which it is to be found close to said roller  20 . This swinging movement of the chassis  21  is achieved thanks to its pivoting assembly at  39  (See FIG. 5) in one and the other sides of the printer frame. 
     In said chassis  21  there is rotationally assembled an auxiliary axis  23  provided with a roller to pull the medium. Said axis  23  has a pinion  24  at one of its ends, which pinion  24  is to be found in constant contact with the toothed wheel  25 . In the first position of said chassis  21 , the said axis is separated from a roller  36  (see FIG. 4) assembled to turn freely in subchassis  37 , while in said second position of said chassis  21 , said at least one roller assembled in said axis  23  achieves being applied with said roller  36  to grasp between both the printing means supplied starting from said storage roll  16 . 
     The toothed wheel  25  has, in its inner face looking towards the printing area, a toothed crown (not shown), intended to mesh, on being required to do so, with a corresponding toothed crown (not represented) formed in the face opposite another toothed wheel  25   a,  coaxial with it and permanently engaged to the main roller  29 . The selective coupling of said toothed wheel  25  with the toothed actuating wheel  25   a  is achieved by movement of the former towards the latter on pushing the lever  26  to said toothed wheel  25  every time the carriage carrying the printer heads, under the control of the logic of the printer, reaches a determined end position, outside the printing area and impacts against part  27  of said lever  26 . 
     The central platen  12  has a slot  28  with a zig-zag design, in which openings are provided (not illustrated) intended to allow the application of a vacuum, generated under said platen, to the upper face of this, on which the printing medium slides. The actuation of this vacuum is limited to the moment at which said medium is fed in, in the form of cut sheet, as shall be explained hereinafter. This platen  12  has ribs  40 , equally spaced the length of the same and penetrating into mouths provided for the purpose in the main feeder roller  29  of the printer. The function of these ribs  40  shall be explained in more detail hereinafter, in relation to FIGS. 6A-6D. 
     In said FIGS. 2 and 3 there can also be seen the main feeder roller  29 , actuated by means of a toothed wheel  30  meshed constantly with said toothed wheel  25   a.  With said roller  29  a pressure roller  31  operates (see FIGS. 4 and 5) for the purpose of grasping between both the printing medium and making it advance or retrocede during operation of the machine. 
     With  32  various rollers to pull the medium are designated, assembled in an axis provided, at one of its ends, with a pinion  33  in constant mesh with said toothed wheel  25   a.  These rollers  32  collaborate, too, with moving the medium in the printing area. 
     Finally, front and rear platens,  34  and  35 , respectively, are provided, intended to support and to guide the medium to facilitate its coming out of the printing area and preventing said medium coming into contact with other mechanisms or cables of the machine and being damaged. 
     Reference will be made now, in particular, to FIGS. 3 and 5, being views similar to those of FIGS. 2 and 4, in which the same elements have been designated with the same reference numbers. In the first of them, the front platen  34  has been removed from the printer, so that the position can be more clearly seen, adopted by the chassis  21  when this is found in its lower swinging position, to which it has been taken by the operator on the latter pressing on the flaps  22  downwards. In FIG. 5 the toothed wheel  25  has been removed and the lever  26 ,  27  which moves it to couple with the toothed wheel  25   a,  so that the pivoting assembly, in  39 , of the brackets  38  constituting the sides of the chassis  21  in the printer frame, can be seen more clearly. 
     The operation shall now be explained of the input system according to the invention, making reference for the purpose to FIGS. 6A-6D in particular, representing different operative phases of the machine. 
     Once the printer is connected, the user manually raises the chassis  21 , pulling the flaps  22  upwards, to move it to its upper or open swinging position (see FIGS.  1  and  2 ). Next, he removes from storage roll  16  of the medium a determined length of the same and causes it to pass above the input roller  20  and above the roller/s  36 , along the path represented with lines in the form of dots and dashes in FIG. 6A, taking care the medium does not break or turn out damaged (for example, creased). The printer, thanks to the existence of a paper detector indicated in general manner with  50 , advises the operator, for example by an acoustic signal, that the existence of the printing medium has been detected. Then the operator lowers the flaps  22  to bring the chassis  21  to its lower or closed swinging position, the medium being grasped between the roller  70  assembled in said axis  23  of the chassis  21  and the rollers  36 . The medium is then made to advance towards the printing area, in the direction of the arrows adjacent to T 1 —T 1  and FIG. 6A, around the main roller  29 , to the flexible fingers  60 , forcing them to divert upwards. These fingers  60  constitute the so-called valve for the medium and are to be found housed in the same periphery slots provided in roller  29  in which there is likewise housed the ribs  40  of the central platen  12 . The medium thereafter passes above said central platen  12 , said rollers  32  and, finally, coming out above said front platen  34 . The path of the medium, in this condition, is indicated, as already stated, by the line comprised by dots and dashes T 1 —T 1  in FIG. 6A, 
     On arriving at this point, the machine interrupts advance of the medium, cutting it transverally to its direction of advance, the length of the entire platen  12 , by means of a cutting device of the kind already known in the art, and remains in the stand by position for printing, alerting the operator of this by the usual acoustic signal. In this condition of stand by to print, of the machine, the continuous medium remains in the T 1 —T 1  position of FIG. 6B, with the printer cover  11  in lowered position. 
     We shall now assume that the user decides to carry out a printing operation on said continuous medium. This will be made to advance as the printer head carries out said task, following the mentioned path T 1 —T 1  (see the arrows of FIG. 6 a ) thanks to the cooperation of the main roller  29  with the roller  31 , while the rollers  20 ,  36  and  70  turn freely. Once the printing task ends, the machine detains advance of the medium, makes a new cut the whole width of the printing area and the printing medium is left to fall on the collection tray  18  (FIG.  1 ), the continuous medium once again being left located in the printer in the condition represented in FIG. 6B with T 1 —T 1 . 
     If, then, the user decides to carry out a printing task on a cut sheet, he lifts the protecting cover  11  of the machine. Every time this step of lifting said cover  11  is performed, a sensor or switch (not shown) is activated, controlled by the cover, causing the logic of the printer to direct the application of a vacuum to the lower part of the central platen  12 . The vacuum acts on the upper part of the central platen  12  through the perforations existing in slot  28  of the platen. The operator can then place in position in the platen  12  a cut sheet, drawing assistance therefore from the slight retention which said vacuum exercises through said platen  12  on said cut sheet. Next the operator lowers the cover  11  to its closed position which activates the same switch and indicates to the printer that the user may have loaded a cut sheet. The printer performs a detection step of said cut sheet (presumed to be in the position designated with T 2 —T 2 ) on the printing platen  12  by way of a detector provided in the carriage bearing the printer heads which, for the purpose, performs an exploration the width of said printing area. 
     If the user has not placed a single sheet on the platen  12 , the printer does not detect its presence and moves on to a stand by condition, the carriage bearing the printing heads returning to its resting position and generation of the said vacuum being interrupted. On the contrary, if the user has in fact placed said cut sheet in the direction T 2 —T 2 , assisted by the action of the vacuum through said platen  12  to achieve its correct positioning, the printer detects its presence and proceeds to remove the continuous medium from the printing area and from the main roller  29  (in the direction of the arrows adjacent to the path T 1 —T 1  in FIG. 6C) and, simultaneously, to take the cut sheet, pulling it in the direction of the arrows of path T 2 —T 2 . 
     To carry out said change of printing medium, the said carriage bearing the printer heads moves outside the printing area, towards the end of the machine where the lever  27  is to be found, touching it and moving it such that the part  26  of said lever moves the toothed wheel  25  to couple it with the toothed wheel  25   a,  whereby the latter will transmit the actuation, through said toothed wheel  25  temporarily meshed with it and through the pinion  24 , to the auxiliary axis  23 , which will be made to turn in a first direction so that the roller  70 , in cooperation with the roller  36 , withdraws the medium downwards, until stopping at the position illustrated in FIG. 6D with T 1 —T 1 . Simultaneously with this removal of the continuous medium, the rollers  32 , in cooperation with the vacuum applied on said cut sheet through the platen  12 , pull this in the direction of the arrows adjacent to the path T 2 —T 2  (FIG.  6 C). 
     On removing the continuous medium T 1 —T 1  from below the flexible fingers  60  of the valve of the medium, these have once again adopted their nondiverted position inside the slots of the roller  29 , so that the medium in cut sheet form T 2 —T 2  continues to move towards the left in FIG. 6C, passing above said fingers  60  and the rear platen  35 , until reaching the position represented in FIG. 6D, following the necessary checks having been made as to position and alignment of said cut sheet in the printing area and the corresponding cutting of its front edge as perparation for a printing operation on it. 
     At this moment, with the continuous medium T 1 —T 1  and the medium in cut sheet form T 2 —T 2  in the positions represented in FIG. 6D, the printer has “parked” the continuous medium T 1 —T 1 , holding it between the roller  70  and the roller  36 , the carriage bearing the heads ceasing to act on the lever  26 ,  27 , said toothed wheels  25 ,  25   a  hence uncoupling themselves and the actuation for the auxiliary  70  axis therefore being interrupted, the machine then beginning the printing task on said cut sheet, once the cover  11  is lowered manually. 
     Once said printing task on the medium in cut sheet form ends, this is ejected from the machine and the tray  18  and the carriage bearing heads moves once again to act on the lever  26 ,  27  in order to transmit the actuation of the toothed wheel  25   a  to the axis  23  and, therefore, to the roller  70 , but now in a second direction opposite to said first turning direction, such that the medium in band form continues to be fed automatically to the printing position represented with T 1 —T 1  in FIG.  6 B. At this moment, on the existence of said continuous medium being detected in this position, the carriage bearing the printer heads is returned to its resting position, separating itself from said lever  26 ,  27 , whereby said toothed wheels  25 ,  25   a  uncouple and the actuation on the axis  23  and the roller  70  is interrupted, the printer once again remaining in the stand by condition on the medium in band form, with the cover  11  in closed position. 
     As from this moment, the machine is to be found in the same starting condition, i.e., with the continuous medium loaded in condition for printing on it, the printer cover in lowered position and in stand by to print condition. 
     It can be seen, from the above, that the feeder mechanism in accordance with embodiments of the invention offers a new solution to the problems that arise at the time of, in printing machines, using a media fed continuously from a roll of the same and, alternatively, a media in the form of cut sheets, on providing a printer of the type mentioned, having two different paths for feeding the media.