Abstract:
An apparatus for printing on sheet material is set-up in a modular fashion having physically added modules, particularly having modules stackable one on top of another, each module including a printing mechanism. The apparatus also includes a modular distributor unit that is distributed amongst the modules for distributing the blank sheet material to the available modules and, if required, for bringing together printed sheet material and for sorting the printed sheet material. The modules are designed such that they can be easily stacked one on top of another, so that no cabling or wiring has to be carried out. The connection of the individual modules with each other is made through a bus system having corresponding connection and expansion interfaces, for example in the form of plug-in connections. A central control unit is provided in a base module, which central control unit recognizes the connected expansion modules through the bus system and configures itself. The central control unit independently distributes the queued printing jobs to available modules and hence achieves optimally short run times for each individual job. The capacity parameters of the printing apparatus can be co-ordinated exactly with the needs of the user by means of the module concept.

Description:
FIELD OF THE INVENTION 
     The invention relates to an apparatus for printing e.g. fotographic images on sheet material. 
     BACKGROUND OF THE INVENTION 
     Colour printing methods are particularly used aside from other image recording methods in the digital image production. However, the colour printers used therefor nowadays and based on inkjet technologies or colouring agent sublimation technologies are relatively slow, and reach a maximum print capacity of typically ca. 50 pictures per hour (based on a picture format of 10 cm×15 cm, for example). Although integrated systems, such as the Canon Hyperphoto System, have a higher capacity, they print on roll material and therefore offer only little formatting flexibility without subsequent cropping of the pictures. Individual sheets are inserted as a stack in common desktop printers, which requires an exchange of the stack of sheets upon a change in format. In order to reach a certain minimum capacity with currently available printers suited for the processing of sheet material, it is necessary to operate several printers of the same type in parallel. This on one hand causes considerable installation cost and on the other hand requires a relatively large mounting area. 
     SUMMARY OF THE INVENTION 
     It is now an object of the present invention to solve this problem and to correspondingly improve a printing apparatus in accordance with the prior art so that the printing apparatus has an increased printing capacity (productivity) on the one hand as opposed to common printing apparatuses and on the other hand can be adapted to changing demands in an easy and economical manner with respect to its productivity. Furthermore, the printing apparatus should require a mounting area which is substantially independent from its printing capacity. 
     According to the principle idea of the invention, the printing apparatus is built in a modular manner and consists of a more or less large number of modules stacked one on top of the other, each of the modules containing a complete printing mechanism with all required components, as well as a distribution system for distributing the queued printing jobs to the individual modules and if necessary to bring them together again or to sort them after printing. 
     With this module concept, the capacity parameters of the printing apparatus can be coordinated exactly with the needs of the user. It is also possible to subsequently increase the capacity of the apparatus through a later addition of further modules or to adapt the capacity to decreased demands through the removal of modules. A further advantage of the modular set-up of the printing apparatus in accordance with the invention is a high flexibility. For example, if one module fails, the total capacity of the apparatus is only reduced by the portion of the failed module but the function of the apparatus is retained as long as at least one module is functioning. 
     In accordance with a further important aspect of the invention, the modules are designed so that they can be easily joined together, i.e. they can be stacked one on top of the other, without having to carry out cabling or wiring. The connection of the individual modules with each other is carried out in accordance with a preferred embodiment through a bus system having corresponding connection and expansion interfaces, for example in form of plug-in connections. In a base module there is provided a central control unit which recognises the connected expansion modules through the bus system and configures itself. The central control unit divides the queued printing jobs independently between the available modules and hence achieves optimally short run times for each individual job. 
     If the modules are equipped with inkjet printing mechanisms, the ink reservoirs are only situated in the base module in accordance with a further important aspect of the invention, and they are common to all modules. The modules are provided with an additional hydraulic bus system, which connects each module with the ink reservoir on one hand and on the other hand facilitates a simple connection of the modules with each other by means of suitable hydraulic connection and expansion interfaces provided in each module, e.g. in form of plug-in pipe couplings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be further described in the following by way of the drawings. 
     FIG. 1 shows a schematic overall presentation in vertical section of a preferred embodiment of the printing apparatus in accordance with the invention; 
     FIG. 2 shows a schematic presentation of the module concept of the invention; 
     FIGS. 3-4 show a schematic block presentation of the most important control units or control functions of the apparatus; 
     FIGS. 5-6 show two sketches for explaining the input and output switching units of the modules of the apparatus; 
     FIGS. 7-9 show three sketches for explaining the set-up of the electrical and hydraulic connection and expansion interfaces of the modules of the printing apparatus; and 
     FIGS. 10-13 show four sketches for clarification of the different transport paths realised through the input and output switching units of the modules of the apparatus. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As it is apparent from the overall presentation of FIG. 1, the printing apparatus in accordance with the invention as presented in this embodiment includes seven modules, in fact a base module M 0  and six expansion modules M 1 -M 6 , which are arranged on the base module in a stacked manner one on top of the other. An end element M 7  is arranged on the uppermost expansion module M 6 , which is not essential for the function and serves only as a physical end of the stack of modules. 
     At the entry side, a cutting unit C is connected in series before the stack of modules composed of the mentioned seven modules M 0 -M 6 . The cutting unit C is cutting individual sheets of desired length in a known manner, off a material web B which is held available in form of a roll so that, the material web B is divided into sheet material S. This sheet material S is supplied to the base module M 0  where it is printed on or, as will be explained below, further guided to one of the expansion modules M 1 -M 6  for printing there. The cutting of the material web into sheet material S is for example known from the paper supply to photographic printers designed for the processing of sheet material and hence no detailed explanation is needed for the person skilled in the art. For the understanding of the present invention it is merely important, that the base module M 0  is supplied with individual sheets to be printed on, i.e. sheet material, and that all modules M 0 -M 6  are designed for the processing of sheet material S. 
     Also, for greater format flexibility, one or more further rollers having material webs of different widths are preferably arranged adjacent to one another, e.g. in axial direction (perpendicular to the plane of the drawing), and means are provided, in order to cut off a sheet from one or another roll of material web as required and to supply it to the base module. Cutting and transport devices suitable for this are also known from the paper supply to photo graphic printers designed for the processing of sheet material and therefore they are not explained in more detail herein. 
     An inclined sorting drawer F 0 -F 6  is assigned to each of the seven modules M 0 -M 6  at the exit side, and the sheet material which was printed in the modules is deposited in the sorting drawer, as will be described below. 
     The six expansion modules M 1 -M 6  are all designed identically. The base module M 0  is build in a substantially same manner as the expansion modules and contains furthermore a few additional components, which will be explained in more detail further below. 
     Each module M 0 -M 6  contains as a central component a complete, conventional printing mechanism P designed for the processing of sheet material, which, for example, is an inkjet printing mechanism. Further, each module contains an input switching unit W E  arranged before the printing mechanism P and an output switching unit W A  arranged after the printing mechanism P as well as a module controller S M  (FIG. 4) not depicted in FIG.  1 . The input switching unit W E  supplies the sheet material S to be printed to the printing mechanism P in a corresponding switching position, and the output switching unit W A  removes printed sheet material S from the printing mechanism P in a corresponding switching position. The printing mechanism P and the input and output switching unit W A  or W E  are each provided with transport and drive members (transport rollers and bands driven by a motor) which are known in the art and thus not presented herein. The module controller S M  controls the printing mechanism P in a manner known in the art, and the input and output switching unit W A  or W E  in cooperation with a central control unit S Z  (FIG. 3) not depicted in FIG. 1, which is provided in the base module M 0 . The image data required for the printing are supplied to the module controller S M  from the central control unit S Z , in a manner which is still to be described. 
     Each input switching unit W E  has a lower or side input  1  that is in communication with the exterior of the respective module, an upper output  2  that is also in communication with the exterior of the respective module, and an internal output  3  that is assigned to the input p 1  of the printing mechanism P of the respective module. Each input switching unit W E  contains two transport paths that lead from input  1  to output  2  or from input  1  to internal output  3  and can be activated alternatively depending on the switching position. The input switching units W E  or their inputs  1  and outputs  2  are arranged in the modules M 0 -M 6  such that each output  2  is aligned with the input  1  of the input switching unit W E  of the module that is arranged immediately above. As is shown in FIG. 1, sheet material S coming from input  1  of the base module M 0  can be supplied in this manner to any printing mechanism P of the seven modules M 0 -M 6  through corresponding combinations of switching positions of the input switching units W E  of the individual modules M 0 -M 6 . The input switching units W E  of the expansion modules M 1 -M 6  are depicted separately in FIG. 10, and those of the base module M 0  are depicted separately in FIG.  11 . 
     Each output switching unit W A  has an upper input  4  that is in communication with the exterior of the respective module, a lower or side output  5  that is also in communication with the exterior of the respective module, an internal input  6  that is assigned to the output p 2  of the printing mechanism P of the respective module, and (with exception of the base module M 0 ) an additional side output  7  that is also in communication with the exterior of the respective module. Each output switching unit W A  of the expansion modules M 1 -M 6  contains four transport paths that lead from input  4  to output  5  or from input  4  to additional output  7  or from internal input  6  to output  5  or from internal input  6  to additional output  7 . The four transport paths can be activated alternatively depending on the switching position. The output switching unit W A  of the base module M 0  contains only two transport paths that lead from input  4  or from internal input  6  to output  5 . The output switching units W A  or their inputs  4  and outputs  5  are arranged in the modules M 0 -M 6  such that each input  4  is aligned with the output  5  of the output switching unit W A  of the module that is arranged immediately above. As is shown in FIG. 1, the sheet material S, which is coming from the output p 2  of the printing mechanism P of any module, can be supplied in this manner to any sorting drawer F 0 -F 6  through corresponding combinations of switching positions of the output switching unit W A  of the individual modules M 0 -M 6 , as long as, the sorting drawer to which the sheet material S is supplied belongs to a module that is not located above the module having the printing mechanism P from which the sheet material S originates. The output switching units W A  of the expansion modules M 1 -M 6  are depicted separately in FIG. 12, and those of the base module M 0  are depicted separately in FIG.  13 . 
     In FIG. 1, some sheets of the sheet material S are drawn in different transport phases to illustrate the resulting various transport paths through different combinations of switching positions. A first sheet is just taken over by the cutting unit C and is on its way to module M 2 . Another sheet is just being supplied to the printing mechanism from the input switching unit in module M 1 . A further sheet coming from module M 5  is guided into the printing mechanism via the input switching unit in module M 6 . Another sheet just exited the printing mechanism in module M 5  and is supplied to module M 3  by means of the output switching unit in module M 4 . A further sheet is still partially within the printing mechanism in module M 3  and is guided to module M 2  by means of the output switching unit. Another sheet is just leaving module M 2  through the additional side output of the output switching unit and slides into a sorting drawer. A last sheet, finally, just leaves the printing mechanism in the base module and is guided into the sorting drawer that is assigned to the base module by means of the output switching unit. 
     The person skilled in the art is familiar with the practical realisation of the input and output switching units W E  and W A  and can be of any construction which guarantees the described functions. A typical example of how a switching function can be principally realized is presented in FIGS. 5 and 6. The switch W presented therein possesses an input  10  and two outputs  20  and  30 . A transport roller pair  11   a / 11   b  is situated at the input  10 . A further transport roller pair  12   a / 12   b  is arranged on the inside. A transport belt  13   a  or  13   b  is respectively wrapped about the transport rollers  11   a  and  12   a  as well as the transport rollers  11   b  and  12   b . Further, three transport rollers  14   a ,  14   b , and  14   c  as well as three further transport rollers  15   a ,  15   b , and  15   c  are provided, the latter being located at the outputs  20  and  30  of the switch W. A transport belt  16   a ,  16   b ,  16   c  is respectively wrapped about the transport rollers  14   a  and  15   a , the transport rollers  14   b  and  15   b , and the transport rollers  14   c  and  15   c . The transport roller pair  12   a / 12   b  is movable in the direction of the double arrow into two positions by means of adjusting members not shown in the figures, wherein it is situated in front of the transport roller pair  14   a / 14   b  (FIG. 5) in one position and in front of the transport roller pair  14   b / 14   c  (FIG. 6) in the other position. The transport rollers and hence also the transport belts are driven by drive motors, not shown, and transport sheet material supplied to the switch W at the input  10  through the switch to its output  20  (FIG. 5) or to its output  30  (FIG. 6) depending on the position of the transport roller pair  12   a / 12   b.    
     A further important aspect of the invention can be seen in that the modules M 0 -M 6  are designed such that they can be easily arranged in series, i.e. stacked one on top of another, without the requirement for cabling or wiring. The electrical connection of the individual modules with each other is thereby achieved with an electric bus system with corresponding connection and expansion interfaces, e.g. in form of plug-in connections. A common electrical energy supply PS for all modules as well as the already mentioned central control unit S Z  are provided in the base module M 0 . The central control unit S Z  communicates with the module controllers S M  in the base module M 0  and the expansion modules M 1 -M 6  and supplies them with necessary control signals and data and also receives responses therefrom. Of course, the module controller of the base module can also be integrated in the central control unit. 
     In particular, the electric bus system that is denoted with B E  is presented in FIG.  2 . It is composed of three partial bus systems, viz. a power supply bus  51 , a data bus  52 , and a communications bus  53 . Naturally, each of the three partial bus systems includes a greater number of cables/lines, of which only one each is presented for reasons of clarity. 
     Each module M 0 -M 6  is provided with an electrical expansion interface  60  on its upper side which connects the electrical bus system B E  to the exterior. Each expansion module M 1 -M 6  is additionally provided with an electrical connection interface  70  on its underside which is designed complementary to the electrical expansion interface  60 . The electrical bus system B E  is connected through from the electrical connection interface  70  to the electrical expansion interface  60  in each expansion module M 1 -M 6 . The electrical expansion interfaces  60  and the electrical connection interfaces  70  are arranged on or in the modules M 0 -M 6  such that the electrical connections are automatically made when the individual modules are stacked one on top of the other. 
     If the modules are equipped with inkjet printing mechanisms, as in accordance with the presented embodiment, the required ink reservoirs IT (for typically six colours) are situated only in the base module M 0  and are common to all modules M 0 -M 6  in accordance with a further important aspect of the invention. The modules are additionally provided with a hydraulic bus system B H , which on one hand connects each module or the printing mechanism P located therein with the ink reservoir IT and, on the other hand facilitates a simple connection of the modules with each other by means of suitable hydraulic connection and expansion interfaces that are provided in each module, for example in the form of plug-in pipe couplings. 
     In particular, the hydraulic bus system that is denoted with B H  is presented in FIG.  2 . It is basically only composed of a number of pipe conduits which corresponds to the number of ink reservoirs IT, of which only three are depicted for reasons of clarity. 
     Each module M 0 -M 6  is provided with a hydraulic expansion interface  80  on its upper side, which leads the hydraulic bus system B H  to the exterior. Each expansion module M 1 -M 6  is additionally provided with a hydraulic connection interface  90  on its underside, which is designed complementary to the hydraulic expansion interface  80 . The hydraulic bus system B H  is connected through from the hydraulic connection interface  90  to the hydraulic expansion interface  80  in each expansion module M 1 -M 6 . The hydraulic expansion interfaces  80  and the hydraulic connection interfaces  90  are arranged on or in the modules M 0 -M 6  such that the hydraulic connections are automatically made when the individual modules are stacked one on top of the other. 
     It is understood, that corresponding ink pumps are provided for supplying the inkjet printing mechanisms P. The ink pumps convey the different printing inks from the reservoirs IT to the printing mechanisms P. However, suitable pumps are known in the art and hence are not presented for reasons of clarity. 
     FIGS. 7-9 show sectional views of exemplary embodiments of the electrical and hydraulic connection and expansion interfaces  60 - 90  of the electrical and the hydraulic bus system B E  and B H , respectively. 
     The electrical expansion interface  60  and the electrical connection interface  70  are designed as a complementary plug-in system. The connection interface  70  includes a socket  71  in which a number of electrical contact prongs  72  are held. The expansion interface  60  includes a corresponding socket  61  in which a number of contact plugs  62  are held. For reasons of clarity only three contact prongs  72  and contact plugs  62 , respectively, are presented. The contact prongs  72  and the contact plugs  62  are connected with electrical lines of the electrical bus system. 
     The hydraulic expansion interface  80  and the hydraulic connection interface  90  are designed as a complementary plug-in pipe coupling system. The connection interface  90  includes a socket  91  holding a number of pipe end connectors  92  therein, of which only one is depicted. The pipe end connectors  92  are each connected with a pipe conduit of the hydraulic bus system B H  and form themselves the ends of these conduits. The expansion interface  80  includes a socket  81  in which a number of cylindrical bores  82  are arranged, wherein only one such bore is depicted for reasons of clarity. The end of a pipe conduit of the hydraulic bus system B H  is held in each bore  82 , wherein the end of the pipe conduit is provided with a flange  83 . Furthermore, a sealing ring  84  is provided in each bore  82 . 
     The sockets  71  and  91  of the electrical and hydraulic connection interfaces  70  and  90  are physically combined into a common socket. Accordingly, sockets  61  and  81  of the electrical and hydraulic expansion interfaces  60  and  80  are physically combined into a common socket. 
     FIG. 9 shows the electrical and hydraulic connection and expansion interfaces in a plugged-in condition, which results when two modules are stacked one on top of the other. 
     FIGS. 3 and 4 show schematically the principal design of the module controllers S M  available in the individual modules M 0 -M 6  as well as the central control unit S Z  provided in the base module M 0 . 
     Each module controller S M  basically includes a printing mechanism controller  101 , an input switch controller  102  activating the input switching unit W E , an output switch controller  103  activating the output switching unit W A , an image data memory  104 , a synchronization controller  105 , and an identification module  106 . Through the latter, the central control unit S Z  in the base module M 0  determines and identifies the presence of an expansion module M 1 -M 6  through the communication bus  53  of the electrical bus system B E . The synchronization controller  105  cooperates with the central control unit S Z  through the communication bus  53  and, under control of the central control unit S Z , operates the input and output switch controllers  102  or  103 , such that the sheet material follows the transport path that is assigned by the central control unit S Z . The image data storage  104  receives the image data representing the images to be printed from the central control unit S Z  through the data bus  52 . Finally, the printing mechanism controller  101  controls the printing mechanism P in a manner known in the art. The power supply of the module controller S M  and of all the components controlled thereby, is carried out through power supply bus  51 . 
     The central control unit S Z  in the base module M 0  is constructed, in a manner known in the art, as a digital computer, which is supplied with energy through the power supply unit PS and is connected to the data bus  52  and the communication bus  53 . The central control unit S Z  is further connected to an external operating unit PC, e.g. in form of a personal computer, which in turn cooperates with an interface unit IFU, or contains the interface unit IFU. Of course, the latter can be directly integrated with the central control unit S Z . 
     The central control unit S Z  contains basically six functional units implemented as software, which are a system monitoring unit  201 , a synchronization unit  202 , a module identification unit  203 , an image data unit  204 , a paper control unit  205 , and an ink control unit  206 . 
     The ink control unit  206  controls the supply of the required printing inks to the individual modules M 0 -M 6  from the ink reservoirs IT through the hydraulic bus system B H . 
     The paper control unit  205  controls the drive for the paper roll R and the cutting unit C. If required, it also allows the selection of different material web widths from different rolls R and then also controls the supply of sheet material S into the base module M 0 . 
     The module identification unit  203  recognizes and identifies the existing expansion modules M 1 -M 6  through the communications bus  53 . 
     The synchronization unit  202  manages the capacity utilization of the base module M 0  and the possibly present expansion modules, in that it distributes the printing jobs to be performed to the modules for performance optimization, and guides the sheet material through the apparatus by accordingly selecting the input and output switching units in the modules. In addition, a sorting of the printed sheet material can be carried out. 
     The image data unit  204  guides the image data supplied from the operating unit PC or the interface unit IFU to the individual modules via the data bus  52 . 
     The system monitoring unit  201  monitors, in a manner known in the art, the function of the remaining components and functional units. 
     The interface unit IFU serves basically for data entry and data output and for the communication of the apparatus or the entire system with other computers. It includes, aside from common communication interfaces in computers, a network interface, a modem, one or more reader devices for data carriers, a connection for a scanner or a scanner itself, a connection for a digital camera etc. In particular, the image data for the printing jobs to be carried out are supplied to the apparatus through the interface unit IFU. 
     It will be appreciated by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restricted. The scope of the invention is indicated by the appended claims rather than the foregoing description and all changes that come within the meaning and range and equivalence thereof are intended to be embraced therein.