FR2784935A1 - Method of predicting quantity of ink required to print job - Google Patents

Abstract

Document to be printed is stored as digital data, used to create table describing some of monochromatic component with each cell representing pixel. Number of switched on pixels in table is counted to find amount of ink needed. Number of switched on pixels is counted until all monochromatic component of document has been entered in table and its switched-on pixels have been counted. Document is divided into groups of data representing pages and pages are selected which would exhaust ink reservoirs simultaneously. There are Independent claims for (1) a device for predicting the amount of ink needed to print a document and (2) a computer program.

Description

 The invention relates to a method for managing the resources of printing products available in a color printer, for printing a document stored in the form of digital data, for example in a computer, the latter being capable of controlling said printer associated with it directly or indirectly via a network.

The invention also relates to a device for implementing the method.

 A color printer contains several tanks of printing products. Certain reservoirs can be integrated in the same cartridge comprising several compartments. For example, a color inkjet printer contains print products of different colors, including cyan, magenta, and yellow. In addition, a reservoir of black print material is provided. On some high performance printers, print products of different shades of these three colors may be used. We can also use other colors such as red, blue, green, white, silver and gold. The printing of a document will use all or part of the printing product (s) present in the various tanks.

Obviously, the quantity of a particular printing product used depends in particular on the content of the document to be printed. A simple typed document will require a single color print product, most often black. On the other hand, an illustrated report may contain images and graphs using colors. In this case, the printer will consume at least black, blue, magenta and cyan in varying proportions.

 The quantity of printing product consumed also depends on the configuration of the printer at the time of printing. Some printers allow you to choose one of several print modes, from low, medium or high resolution, in black and white as in color. Consequently, the same printer may consume very different quantities of printing products, for the same document stored in digital form, according to the selected printing mode.

 The quantity of printing product consumed also depends on the physical characteristics of the printing means. It depends in particular, for an inkjet printer, on the type of reservoir or cartridge used, on the diameter of the ink ejection nozzles of the printing head and on the very nature of the printing product, the size ejected drops depending on the pigments used, therefore on the color.

 The quantity of printing product consumed also depends on the characteristics of the paper used. For example, heavyweight glossy paper will need more print material than plain paper.

 Finally, it should be noted that the quantity of printing product consumed also depends on the characteristics of the environment: humidity rate, pressure, temperature, etc. These characteristics are unstable by nature and distort predictions. All the others can be predetermined or known.

 For all these reasons, it is common for one tank to empty well before the others. If all the tanks are independent, it is possible to avoid wasting expensive printing products but frequent interventions are necessary. If tanks are combined in the same cartridge, the exhaustion of one leads to the waste of products of other colors.

 It is therefore desirable not only to be able to measure the quantities of printing products available in the tanks at a given time but also to be able to predict the quantities necessary for printing a document (as soon as it is stored in form of digital data) or different parts of it, including the different pages that should make it up. From these two sets of information, we can consider better managing the use of resources in printing products.

 US Patent No. 5,636,032 describes a system for estimating the number of pages that a printer is capable of printing.

When the document is stored in the form of digital data, it is converted to constitute a table describing a monochromatic component of the document in the form of pixels. Reading such a table makes it possible, in the case of an inkjet printer, to control the ejection of the drops of liquid printing product at predetermined locations on the sheet of paper, constituting the coordinates of the different pixels. A pixel is said to be "lit" in such a table if the cell corresponding to this pixel contains information indicating that a drop of printing product must be ejected at this pixel location.

 According to the teaching of this prior patent, at the very moment of the printing of one of the pages, the number of pixels lit on this page is counted and the or each quantity of printing product used to print it is deducted. . This process can only achieve a relatively imprecise estimate of the quantities required since it is implemented simultaneously with the printing of a page. The estimate therefore assumes that all the pages that remain to be printed will require the same quantities of printing product as the previous ones. This is rarely the case in practice.

 Furthermore, some printers are provided with means for measuring the or each quantity of printing product available in a reservoir or cartridge compartment in use. Such a printer is for example described in PCT application 97/00366. If the printer is connected to a computer, the measurements can be transmitted to the latter via an interface card and they can be processed and / or displayed on a control screen of this computer.

 The main object of the invention is to improve the management of the resources of the printing products used by the color printer, in particular in connection with the computer, by combining predictions of the quantities of printing product necessary for printing a document. and the effective measurements of the quantities of printing product available in the tanks of the printer at the time when it is desired to print.

 The basic idea is to choose the printing order of the different pages so that at least several tanks are empty or almost empty at the same time.

 More specifically, the invention relates to a method for managing the resources of print products available in a color printer containing several reservoirs of different print products, characterized in that it consists in sharing a document stored in the form of digital data. , in groups of such data representing pages, to predict the quantity of each printing product necessary for the printing of each page, to measure moreover, before printing, the quantity of printing product actually available in each reservoir, to search for a selection of pages which would ensure at least approximately simultaneous depletion of at least one group of reservoirs, and to at least send a message and / or trigger the implementation of a processing operation, involving said selected pages, such as for example the printing of such selected pages.

 Among the messages that can be displayed, we can mention the prediction of the quantities of printing products necessary to print each page, the quantities available after printing, information on the possibility or impossibility of actually printing the entire document without have to change at least one tank. Above all, the information disseminated may also indicate the pages of the document (for example identified by their numbers) that it is possible to print without having to change at least one tank, knowing that the possible selection of such pages can save less printing products, especially if certain tanks are part of the same cartridge.

 The step consisting in searching for a selection of pages which would ensure the simultaneous exhaustion of at least one group of reservoirs is all the more time-consuming to implement when the number of pages is high. It is advantageous to find out whether part of the document to be printed can be in the natural order of the pages and nevertheless allow the quasi-simultaneous exhaustion of at least several reservoirs.

 Consequently, the process defined above can be supplemented by the operations consisting in predicting the quantity of each printing product necessary for printing pages in their natural order, in updating after each series of predictions concerning a page the quantity of each print product that would actually be available in each tank, to check after each update if at least several tanks are almost empty, to actually print the pages thus tested and at least to send a message indicating the need to change or fill out tanks.

 After changing the reservoirs concerned, processing is resumed on the remaining pages, considering a reduced number of pages.

During the processing of the pages in their natural order, the predicted quantities of products consumed for each page are memorized, with a view to a possible need for selection.

 It should be noted that the operations consisting in predicting the quantity of each printing product necessary for the printing of each page can be done a priori, as soon as the document has been divided, in digital form, into groups of digital data representing pages.

 As we will see later, we can make the predictions once and for all and in this case, an operation consisting in predicting an amount of printing product necessary for the printing of a page boils down to fetching the precalculated value in a memory where it was previously registered. A prediction operation can therefore, depending on the case, consist of an effective calculation which will be explained below or a simple reading of a memorized value, previously calculated during the course of a process of global and autonomous prediction of the quantities of products. required to print each page.

 The implementation of an actual page selection process is triggered by a specific test. More particularly, we check page after page if we go from a state where all the tanks of said group would be non-empty to a state where at least one of them would be completely empty. We decide to implement such a selection when this event occurs. When such a selection is decided and if the quantities of printing product necessary have not been calculated beforehand, the quantity of each printing product necessary to print the remaining pages is predicted and stored. The selection then consists in searching for a subgroup of pages whose printing would result in at least several reservoirs being almost empty at the end of the printing of these pages. Such a selection is particularly advantageous if the subgroup is such that all of the corresponding reservoirs are structurally linked and form a cartridge.

In this case, the selection would result in finding the pages to be printed so that all the tanks of the cartridge are empty after the printing of said subgroup. As a variant, it can be satisfied that only several reservoirs of the cartridge are empty at the end of the printing of this subgroup. If the selection process leads to a satisfactory solution, said subgroup of pages is effectively printed and at least one message is sent indicating the need to change or fill tanks.

 The process which has just been stated may preferably be essentially implemented in a computer connected to a printer.

However, it is more and more common to use networked computers.

Under these conditions, if a computer contains a document stored in digital form, it will be possible to have this document printed by a specific printer connected to another computer on the network. The predictions can be calculated by the computer containing the document before it is transmitted to the other computer specifically connected to the printer in question. In this case, the necessary parameters relating to the characteristics of the printer and of the printing products and those relating to the choice of the printing mode, may be exchanged by the network between the computers.

 To prevent the representation of the or each monochromatic component of said document in the form of pixels from occupying too large a place in the computer memory, the method according to the invention is supplemented by the fact that an aforementioned capacity table is created. limited, less than the capacity necessary to describe the or each monochromatic component of said document. There are successively written therein groups of pixels of said monochromatic component and the number of lit pixels is counted each time until all of said monochromatic component has been entered in said table and all of its lit pixels have been counted.

 Preferably, each table of limited capacity is created from digital data representative of adjacent bands of the document.

 In order to be able to apply to the digital data represented in the form of pixels corrections desirable for printing, by implementing known correction algorithms, the method according to the invention provides for selecting widened, overlapping bands of said document.

From the digital data corresponding to these enlarged bands, at least one enlarged table is created allowing an image reprocessing implying a modification of the lit pixels. Consequently, the enlarged table is modified by application of a known correction algorithm and the lit pixels corresponding to the excess part of the enlarged table, that is to say the overlapping part of the bands, are excluded from the accounting.

 For a color print, as many enlarged tables are created as there are colors, each describing a monochromatic component of the document. A correction algorithm is applied in a manner known per se to each table before separately counting the lit pixels so as to predict the different quantities of printing products required, of all the colors concerned, to print part of the document. corresponding to the band. After which, the reset tables receive the pixels of the next strip.

 When the lit pixels have been counted, it suffices to multiply their number by a value representing an elementary quantity of the printing product. In the case of an inkjet printer, the value in question represents the volume of a drop of print product ejected each time by the print head. Obviously, this value depends on the printing product, as indicated above. It also depends on the type of printer and / or the type of print head. A computer can easily store in memory a set of such values taking into account all of the equipment and products available on the market and it will be able to select one of them according to an effective combination of such parameters.

 As regards the effective measurement of the or each quantity of printing product available in the or each corresponding reservoir, it is possible, for each reservoir, to arrange a capacitive branch including said reservoir, apply an alternating signal to this capacitive branch and analyze a resulting signal to deduce therefrom said quantity of printing product actually available in this reservoir.

 Of course, the invention also relates to a device for managing the resources of printing products available in a color printer containing several reservoirs of different printing products, characterized in that it comprises means for sharing a document stored in the form digital data, in groups of such data representing pages, means for predicting the quantity of each printing product necessary for the printing of each page, means for measuring, before printing, the quantity of printing product actually available in each reservoir, means for searching for a selection of pages which would ensure at least approximately simultaneous exhaustion of at least one group of reservoirs, and means for transmitting a message and / or triggering the implementation of a processing , involving said selected pages, such as for example the printing of such selected pages.

The invention will be better understood with the aid of the following description of a computer system comprising a printer and at least one computer equipped and programmed to implement the invention, given solely by way of example and made in reference to the accompanying drawings in which:
FIG. 1 is a block diagram of a computer-printer assembly implementing the invention;
FIG. 2 is a block diagram of the means specific to the implementation of the invention for predicting the quantity of each printing product necessary for the printing of a color document stored in the form of digital data;
FIG. 3 is a flowchart describing the implementation of the prediction method;
FIG. 4 is a block diagram of a printer incorporating means for measuring the effective quantity of printing product contained in each reservoir;
FIG. 5 is a view of the color printer with its reservoirs of printing products;
FIG. 6 is a flow diagram of the overall implementation of the method of the invention; and
FIG. 7 is a flow diagram of the implementation of a selection of pages, constituting a step of the method.

 FIG. 1 shows a computer 20 connected to various peripherals, including a printer 210. The computer comprises a communication interface 510 connected to a communication network 400 by which it can in particular exchange information with other computers. It also includes a storage means 506 called a "hard disk", a floppy drive 507 and a "CD" disc drive 508. These drives can respectively receive a floppy disk 700 and a "CD" disk 701. These elements as well as the hard disk 506 can contain documents within the meaning of the invention, as well as the code for implementing the invention which, once read by the computer 20, will be stored in the hard disk 506. According to a variant, the program allowing the computer to implement the invention may be stored in read-only memory 501 (designated ROM in FIG. 1). According to another possible variant, the program can be loaded on demand to be stored in an identical manner to that described above, via the network 400.

 The computer is completed by a screen 503 making it possible to view the documents to be printed, to serve as an interface with the user who wishes to modify these documents, using a keyboard 504 and / or a "mouse" 505 or any other means of control. The screen 503 also makes it possible, at the request of the user, to display the volumes of the various printing products which will be likely to be consumed by the printer 210 if a document available in the form of digital information in the the computer or one of its peripherals must be printed. These volumes can be determined and displayed for each page. The instructions relating to the implementation of the method according to the invention are executed by a central unit 500 (CPU in FIG. 1). The instructions are stored in the read-only memory 501 or in the other available information storage elements. When powering up, the programs relating in particular to the implementation of the invention, stored in one of the non-volatile memories, such as for example the read-only memory 501, are transferred to a random access memory 502 (RAM in FIG. 1 ) which then contains the executable code of the invention as well as the variables and parameters necessary for its implementation.

 The various sub-assemblies of the computer 20 which have just been mentioned exchange information with one another via a communication bus 512, which also makes it possible, thanks to the interface 510, to convey information coming from the network 400 or from transmit information to this network. As regards the possible reproduction of images, a digital camera 800 can be connected to the bus 512.

 FIG. 2 shows a functional block diagram of a device 100 capable of implementing the process of predicting the or each quantity of printing product necessary for printing, page by page, of a document, since it is functionally interposed between a file 1 containing the document in the form of digital information and a screen 11 capable of displaying the results, that is to say the quantities of printing products necessary for printing of the document stored in the file 1. The device can, as we have seen, be made concrete by the computer, it can also be produced in the form of an autonomous unit housed in the printer itself or being part of an interface circuit. The device comprises a page cutter 2 responsible for sharing the electronic document stored in the file 1 into groups of information, each group representing a page. Each page comprises a more or less important part of the document according to the format chosen for the reproduction, the size of the sheets of paper, etc. The representative information of each page is then divided into enlarged bands by a widened band cutter 3. It will be recalled that such an enlarged band consists of digital information representative of a band of the page considered increased by an overlap margin belonging to the next band.

The extended band information determined by the cutter 3 is transmitted to a conversion system, called a "rasterizer" 4 which transforms the digital information transmitted by the cutter 3 into several tables Ta, Tb, Tc, Td ... each describing a part of a monochromatic component of the document, each cell of the table representing a pixel. More precisely, each cell of an array (memory) contains the coordinates of a pixel and information representative of whether this pixel is "lit" or not. In the example, the part of the monochromatic component is that which corresponds to the enlarged band being processed. Being a document to be printed in color, the rasterizer 4 generates as many tables Ta, Tb, Tc, Td as monochromatic components are necessary to print the document, for example, black, cyan, magenta and yellow. Each table is then subjected to the faction of a corrector 5 capable of applying to the table a correction involving modifications of the lit pixels, making it possible to improve the quality of the document to be printed. The corrector 5 implements known algorithms. When the corrector has applied such algorithms, to modify the pixels lit in the various tables Ti; these are read and the so-called lit pixels are counted by a lit pixel counter 6. It should be noted that this counter only counts the lit "useful" pixels of the or each table, that is to say the pixels corresponding to the band considered, not including the margin of overlap with the next band. The results of these counts are sent to a calculator of the volumes of printing product which multiplies the number of pixels lit in each table by a predetermined quantity calculated from information selected from memories 7, 8 and 9.

 For example, memory 7 makes it possible to select a parameter representative of the printer model. The memory 8 makes it possible to select a parameter representative of the type of reservoir or cartridge. The memory 9 makes it possible to select a parameter representative of the printing product used.

 All of these parameters make it possible to calculate the average volume of a drop of printing product ejected at the location of each lit pixel. The computer 10 determines the volumes of the corresponding printing products and, when all the strips of all the pages of the document have been analyzed, the computer 10 can control the display, on the screen 11, of the volumes of the different products of printing required to print each page on the one hand, and the entire document on the other.

 In addition, according to the invention, information on a selection of pages to be printed in order to optimize the consumption of printing products is also displayed on the screen 11, after implementation of the method described below.

 FIG. 3 is a flowchart describing more precisely the operations executed during the implementation of the prediction process, for example by means of the computer of FIG. 1 connected to its printer 210 or to a printer accessible by the network 400 via another computer. We start from a file 101 in which the document to be printed is stored in the form of digital information.

 The following operation 102 consists in initializing the total volumes of the printing products in a memory which will be consulted for the final display. The following operation 103 consists in reserving in the system the memory capacity necessary to create as many enlarged tables as there are different print products to print the document.

 Operation 104 consists in selecting a first page in the digital information contained in the file 101.

 Operation 105 is a test to check whether the last page has been processed.

 If the answer is no, we go to step 106 of initializing the quantities of printing products necessary for a page, in a memory reserved for this purpose, which will be consulted for the final display.

 The next step 107 consists in selecting a first enlarged band on this page.

 Step 108 is a test to determine if all the bands on the page have been processed.

 If the answer is no, we go to step 109 which consists in initializing all the enlarged tables corresponding to the different monochromatic components of the band.

 The next step 110 (rasterization) consists in filling all the enlarged tables corresponding respectively to the monochromatic components of the enlarged band during processing.

 Operation 111 consists in applying the correction algorithms to all the enlarged tables of said enlarged band.

 Operation 112 consists in choosing one of these tables for the purpose of counting the lit pixels thereof.

 Operation 113 is a test which checks whether all the tables corresponding to a widened band have been processed.

 If the answer is no, we go to step 114 which consists in counting the "useful" pixels of the table considered.

 Step 115 consists in calculating the quantity of the corresponding printing product. This calculation takes into account the values of the parameters selected in different memories 7,8 and 9 as in the case of FIG. 2, to take into account the model of the printer, the type of cartridge used and the print product itself .

 Operation 116 consists in adding the quantity calculated in operation 115 to the quantities previously recorded and added.

 In operation 117, select the following enlarged table and return to step 113.

 When all the tables have been processed, the response to test 113 becomes positive and we go to a step 118 consisting in selecting the next enlarged band before returning to test 108.

 When the response to test 108 becomes positive, this means that the entire page has been tested and we go to step 119 which consists in processing the next page by returning to test 105.

 When all the pages have been processed, the test 105 becomes positive and we are then able to display the total quantities (step 120) of all the printing products necessary for printing the entire document as well as the partial quantities (step 121) indicating the corresponding quantities required to print each page.

 Besides the means of predicting the quantities of printing products necessary for printing of different colors, for color printing. The three colors are conventionally magenta, cyan and yellow.

In the example, the tanks 312a-312d and the printing heads 313a-313b are mounted on a carriage subject to move along guide means formed by parallel rods and rails. The carriage is moved back and forth along these guide means. 11 is driven by a motor 302, by means of a belt mechanism, well known from
The skilled person. The path of movement of the carriage and therefore of the printing heads 313a-313d is parallel to a line to be printed on a printing medium such as a sheet of paper. This print medium is moved perpendicular to the movement path of the carriage by the printer mechanism, known per se.

 The printer also comprises a main data processing circuit 300 associated with a read-only memory 303 and a random access memory 309.

The read-only memory 303 contains the operating programs of the main processing circuit while the random access memory 309, also associated with the print product ejection control circuit 310, temporarily stores the data received via the interface 306 as well as the data produced by the main processing circuit 300. The latter is connected to a display 304 on which it controls the display of messages indicative of the operation of the printer in general, and in particular, as is will see further on, information on the quantity of printing product remaining in the reservoir. This information can of course be transmitted to the computer to be displayed on the screen 503.

 The main processing circuit 300 is connected to a keyboard 305 by which the user can transmit operating commands to the printer. The processing circuit also controls the motor 302 which drives the carriage, by means of an amplification circuit 301. This motor is advantageously of the stepping type here.

 Means for measuring the quantities of printing products contained in the various reservoirs comprise a capacitive arrangement 308a-308b, selected by a selector 325, comprising a reservoir and the corresponding printing head as well as a metal plate 321a, 321b, 321, 321d constituting one of the armatures of a capacitor including the corresponding reservoir.

 More precisely, it can be considered that this metal plate 321a-321d constitutes, from the electrical point of view, the armature of a capacitor connected to an extremum detector of the detection and measurement means 315 of the printer. These consist more particularly, mounted in cascades, of an amplifier 350 whose input is connected to the frame 321, of an extremum detector 351 controlled by the main processing circuit 300, in particular for its delivery at zero and of an analog-digital converter 352 whose output communicates with the main processing circuit 300. The latter is programmed to detect and store a digital value delivered by the converter 352 and representative of a signal extremum applied to the input of amplifier 350 after resetting the extremum detector 351.

 A resonant circuit comprises an adjustable frequency oscillator 317, controlled by the main processing circuit 300, the output of which is connected to an amplifier 319 which applies signals, through a resistor 322 to the resonant circuit comprising a self-inductance 324 and a capacitive arrangement 308a-308d selected including the frame 321a-321d, the reservoir 312a-312d and its conductive printing product, the printing head 313a313d connected to the reservoir and the resistor 323a-323d of low value connected to ground. The assembly forms an equivalent capacitive branch, from the electrical point of view, with two capacitors and a resistor connected in series. Thus, such a capacitor is constituted by the armature 321, by the insulating wall of the reservoir 312 as a dielectric and by the conductive printing product contained in the reservoir as the second armature of the capacitor. Furthermore, the printing head 313 has a dielectric part and a conductive part which form the other capacitor, the latter being connected to ground by the resistor 323 of low value. The various armatures 321a-321d are connected to the input of the detector 315 and to the other constituents of the resonant circuit by the selector 325 controlled by the circuit 300.

By this means, each capacitive branch can be put into service successively.

 Each measurement of a quantity of product actually available in a reservoir consists, for example, in applying an alternating signal to one of the capacitive branches connected to the rest of the resonant circuit to seek the resonance conditions and to analyze a resulting signal applied to t ' input of the detection and measurement means 315 to deduce therefrom the quantity of printing product available in this reservoir.

 Of course, the invention can be implemented with any type of system for measuring the quantities of printing products available in the tanks; the capacitive system described above being only one example.

 Figure 5 shows the structure of a conventional color inkjet printer. There is a carriage 60 adapted to receive a printing unit 61, the lower part of which comprises the printing heads 313a313d and the upper part of which forms a receptacle for the reservoirs of printing product. In the example, a distinction is made between the reservoir of black print product 312a and a cartridge 64 compartmentalized internally to form all of the reservoirs 312b-312d. Consequently, in this way of arranging the reservoirs, there is a very particular interest in the fact that the compartments of the cartridge 64 are emptied practically simultaneously since the cartridge must be changed as soon as one of the printing products, cyan, magenta or yellow is exhausted. The process according to the invention described below modifies the printing order of the pages to obtain this result. To simplify the description, the following flowcharts are established only by considering three printing products of cyan, magenta and yellow colors.

However, the same process can be used by integrating monitoring and taking into account the level of black printing product contained in the reservoir 312a.

 The unit 61 once placed on the carriage 60 is driven in a back-and-forth movement along a movement path formed by guide rails 67. The motor 302, not visible in FIG. 5, drives the carriage 60 by means of a belt device 63. The path of movement of the printing heads is parallel to a line of a printing medium, not shown, such as a sheet of paper. A flat strand of electrical cables 62 establishes the connection between the printing heads and the rest of the electronic circuits described with reference to FIG. 4.

 The flow diagram of FIG. 6 illustrates the process of selecting the pages in accordance with the invention in order to optimize the consumption of the printing products, using the data supplied, on the one hand, by the means for measuring the product levels d printing available in the tanks (here the word tank actually designates a compartment of the cartridge 64) and, on the other hand, the predictions of the quantities necessary to print each page. In the example, it is assumed that all the necessary quantities have been determined a priori by implementing a process in accordance with that which has been described with reference to FIG. 3. It is therefore assumed that all these quantities, Ci for the cyan, Mi for magenta and Ji for yellow, are available in a memory of the computer or printer. It is clear that i indicates the page number in the natural order of the document.

 In step 401, the actual levels of the quantities actually available in the tanks, C, M and J, are measured, for example by using capacitive measurement means described with reference to FIG. 4.

 In step 402, three variables Cp = C, Mp = M and Jp = J are initialized.

 We then go to a step 403 initializing a process concerning the first page P1. In other words, we consider the values of index i for i = 1.

 In step 404, we will look in memory for the predicted quantities of print product, necessary to print the page in question. These quantities are noted, for the i th page, VCi, VMi and VJi.

In step 405, the levels Cp, Mp and Jp are updated after (virtual) printing of the page considered. The new values are:
Cp-VCi Cp Mp-VMi Mp Jp-VJi o Jp
As a variant, if we do not have all the values in memory
VCi, VMi and VJi,! Step 403 consists in extracting from a file the digital information representing the page and in transmitting it to the system of prediction of the necessary quantities, previously described. Step 404 then no longer consists in simply reading the values in memory but in calculating them at this time.

 Step 406 is a test which consists in checking whether all the quantities of printing products available in the various reservoirs after virtual printing of a page are close to zero, by excess, with a given tolerance, for example of around 5%. If the answer to test 406 is negative, we pass to test 411 which checks whether one of the values Cp, Mp or Jp has become "negative" which means that at least one of the printing products would be in insufficient quantity in the tank to allow the correct printing of the page in question. If the response to test 411 is negative, we go to step 413 which consists in checking whether the page which has just been processed virtually is the last page of the document. If the answer is no, we go to step 413 which consists in "obtaining" the next page in the natural order of the document; i = i + 1 and we return to step 404.

 If at a given moment in the course of the loop which has just been described, the response to test 406 becomes positive, this means that the natural order of the pages up to a certain page is suitable for practically simultaneously emptying the tanks at the same time . We then go to step 407 which consists in printing pages 1 to i in the natural order of the document, even if these pages represent only part of the document. We then go to step 408 which consists of displaying a message indicating to the user the need to change the tanks, that is to say in this case the cartridge 64. Once this operation has been carried out, the process passes in step 409 which consists in effectively measuring the levels C, M and J in order to know the quantities available in the tanks which have been replaced. The step 416 which follows is an initialization step analogous to the step 402. From this moment, we consider the remaining pages as a reduced document and we go to step 417 which consists in "obtaining" the first page of the remaining pages. We then consider i = 1 and go back to step 404.

 If at a given point in the progress of the process, the response to test 411 is positive, we pass to a step 415 which consists in selecting all the remaining pages (not actually printed) to define a selection thereof, which is not more in the natural order of the document pages.

The process of step 415 will be explained with reference to FIG. 7. If this process leads to a positive result, we go to step 414 which consists in printing a selection of pages determined by the process of step 415.

 Furthermore, if at a given time, the response to test 413 is positive, this means that the entire document can be printed without changing the reservoirs and we also go to step 414 of printing.

 FIG. 7 describes more precisely the selection and ordering process of the remaining pages triggered when the test 411 indicates that at least one of the reservoirs does not contain a sufficient quantity of printing product to print a page considered .

The flow diagram of FIG. 7 represents the adaptation to the invention of a recursive operational research program (that is to say capable of calling itself) of the type "research in depth first" . Such a program is for example described in a work entitled "Elementary Graph
Algorithms "second edition by Robert Sedgevick, chapter 29, page 423, ISBN reference 0-201-06673-4.

 In this algorithm, Q represents the list of pages to be processed while R represents the list of pages selected in a given order.

The purpose of the processing is therefore to develop a list R from elements of the list Q subtracted from it in a certain order. The program begins with a test 601 consisting in checking whether the set Q is empty. If the answer is no, we go to operation 602 consisting in selecting a page i from the set Q, possibly at random. We then go on to operation 603 consisting in removing page i from the set Q, then in operation 604 consisting in adding page i to the set R. Then operation 605 consists in "calling up" the quantities of print product VCi, VMi and VJi, already memorized. as a variant, if these quantities have not been previously stored, they can be calculated at this stage.

Next, operation 606 consists in defining temporary variables Ct, Mt and Jt representing the quantities of printing products actually available in the various tanks at this time, that is to say before the virtual printing of the page. considered. We have: Cp Ct
Mp Mt Jp Jt
Operation 607 consists in calculating the quantities available after printing the page in question and therefore obtaining new virtual values for Cp, Mp and Jp. We then pass to a test 608 consisting in checking whether each of these quantities is practically zero by excess, for example to the nearest 5%. If the answer is no, we pass to test 610 which consists in checking whether at least one of these values has become "negative". If the answer to this test is negative, we go to step 620 which in fact symbolizes the recursion of the program, that is to say the possibility of calling itself for the rest of the pages. In this case, the other pages are processed starting from step 601.

If at some point the result of test 601 is positive, the program ends. Each recursive call 620 is followed by a test 621 consisting in checking whether the set R is complete, that is to say whether an order meeting the requirements has been found. If the answer is yes, a print order is issued and the program ends.

 Furthermore, if the response to test 608 is positive, this means that a certain number of pages have been found making it possible to empty almost all the tanks simultaneously. This information is stored and displayed.

We then go to step 609 simulating a change in the reservoirs since the values of Cp, Mp and Jp become C max, M max and J max respectively.

We then go to step 620, that is to say recursively calling the luimme program for the rest of the pages.

 Furthermore, if the test 610 becomes positive, we pass to the test 611 consisting in checking whether the ratio between Q and R is less than a predetermined value, for example of the order of 5%. If the answer is positive, we consider that the losses of print product are acceptable and we decide to print the previous pages, except the last one which led to the positive 610 test. This is step 627.

 Then, in step 628, a message is displayed indicating to the user the need to change the tanks (the cartridge). We finish with step 629 consisting in printing the rest of the pages with the print products of the new cartridge.

If the response to test 611 is negative, or if the response to test 621 is negative, this means that there is no possible solution starting from a selection of page i. In this case, we go to step 623 which consists in returning to the values of Cp, Mp and Jp before virtual printing (that is to say in step 606) then in operation 624 which consists to remove page i from the set
R then again to operation 625 which consists in reintegrating page i into the set Q. These parameters being restored, we then go to step 626 which consists in testing another selection starting from another page i while refraining from resuming the page i which has just been tested. We then return to step 603.

 Of course, the invention also relates to any device, (that is to say any device or set of devices interconnected with each other) comprising means for implementing the method described above. These means have been described here with reference to FIGS. 1, 2, 4, 4 and 7. In this case, such a device can consist of at least one computer and a printer, or even two computers connected in a network with at least one printer.

 The invention covers any storage means such as magnetic tape, floppy disk, "CD-ROM" (compact disk with frozen memory) or rewritable compact disk, integrated or not in the device, possibly removable, as soon as it contains a program putting implementing, at least partially, the process described. Such a storage means can be read by a computer or a microprocessor for implementing the method.

Claims (37)

 1-Method for managing the resources of printing products available in a color printer containing several reservoirs of different printing products, characterized in that it consists in sharing (2) a document stored in the form of digital data, in groups such data representing pages, to predict (10) the quantity of each printing product necessary for the printing of each page, to measure (317,324,315) moreover, before printing, the quantity of printing product actually available in each tank, to search for a selection of pages (415) which would ensure at least approximately simultaneous depletion of at least one group of tanks, and to at least send a message and / or trigger the implementation of a processing, involving said selected pages, such as for example the printing of such selected pages.  2-A method according to claim 1, characterized in that it consists in predicting the quantity of each printing product necessary for printing pages in their natural order!, To update after each series of predictions concerning a page the quantity of each print product that would actually be available in each tank, to check (406) after each update if at least several tanks are almost empty, to actually print the pages thus tested and at least to send a message (408), indicating the need to change or fill tanks.  3-A method according to claim 2, characterized in that, after changing the tanks, the processing is resumed (417) on the remaining pages considering a reduced number of pages.  4-A method according to claim 2 or 3, characterized in that during the processing of the pages in their natural order, it stores the predicted quantities of products consumed for each page, for a possible need for selection.  5-Method according to one of the preceding claims, characterized in that, to make a selection, it is checked page after page if we go from a state where all the reservoirs of said group are not empty to a state (411) where at least one of them would be completely empty and such a selection is decided (415) when this event occurs.  6-A method according to claim 5, characterized in that, when such a selection is decided, the quantity of each printing product necessary to print the remaining pages is predicted and stored.  7-A method according to all of claims 4 and 6, characterized in that said selection consists in searching for a subgroup of pages (620) whose printing would result in at least several reservoirs being almost empty at the end of the printing of these pages.  8-A method according to claim 7, characterized in that said subgroup is such that all structurally trusted tanks (61) and forming a cartridge, would be empty after the printing of this subgroup.  9-A method according to claim 7, characterized in that said subgroup is such that several structurally linked reservoirs and forming a cartridge would be empty after the printing of this subgroup.  10-A method according to claim 8 or 9, characterized in that said subgroup (627) is actually printed when it can be determined and in that at least one message (628) is sent indicating the need to change or fill tanks.  11-Method according to one of the preceding claims, characterized in that it consists in predicting said quantity of such a product necessary for the printing of such a page by describing this page by pixels (4) and by counting ( 6) the lit pixels corresponding to said print product.  12-A method according to claim 11, characterized in that the prediction of each necessary printing product consists, from said digital data of the page considered, to create a table (Ta, Tb, Tc, Td) describing at least one part of a monochromatic component of said document, said component corresponding to said print product and each cell of said table representing a pixel, to count the number of pixels lit in this table and to deduce therefrom a necessary quantity of corresponding print product mentioned above .  13-A method according to claim 12, characterized in that one creates an aforementioned table of limited capacity, less than the capacity necessary to describe said monochromatic component of said page, in that there are successively written therein groups of pixels of said monochromatic component of said page, in that each time the number of lit pixels is counted until all of said monochromatic component of said page has been entered in said table and its lit pixels have been counted (FIG. 3 ).  14-A method according to claim 13, characterized in that it consists in creating each table of limited capacity from digital data representative of adjacent bands of said page.  15-A method according to claim 14, characterized in that one selects overlapping widened bands, in that from the corresponding digital data one creates at least one enlarged table (103) allowing an image reprocessing implying a modification lit pixels, in that said table is modified by application of a known correction algorithm (111) and in that the lit pixels corresponding to the excess part of said enlarged table are excluded from the accounting.  16-A method according to claim 15 for color printing, characterized in that as many enlarged tables (103) are created as there are printing products, each describing a monochromatic component of said page, in that a correction algorithm (111) is applied in a manner known per se to all the tables before separately counting the lit pixels of each table for the prediction of the different quantities of printing products required, of all the colors concerned.  17-Method according to one of claims 12 to 16, characterized in that it comprises a calculation step consisting in multiplying (10) the number of pixels lit by a value representing an elementary quantity of said printing product.  18-The method of claim 17 for an inkjet printing system, characterized in that said value represents the volume of a drop of ejected print product.  19-A method according to claim 18, characterized in that the said value is preselected according to predetermined parameters, such as, for example, the type of printer (7) and / or the type of cartridge (8) and / or the type of printing product (9).  20-A method according to claim 19, characterized in that it stores a set of such values and in that one of them is selected according to an effective combination of such parameters.  21-Method according to one of the preceding claims, characterized in that the or each measurement of an amount of product actually available consists of arranging a capacitive branch including said reservoir (312a, 312d), applying an alternating signal (317) to this capacitive branch and to analyze a resulting signal (315) to deduce said quantity of print product actually available.  22-Device for managing the resources of printing products available in a color printer containing several reservoirs of different printing products, characterized in that it comprises means for sharing (2) a document stored in the form of digital data, in groups of such data representing pages, means for predicting (10) the quantity of each printing product necessary for the printing of each page, means for measuring (317,324,315), before printing, the quantity of product printing actually available in each tank, means for searching for a selection of pages (415) which would ensure at least approximately simultaneous exhaustion of at least one group of tanks and means for sending a message and / or triggering the implementation processing, involving said selected pages, such as for example the printing of such selected pages.  23-Device according to claim 22, characterized in that said means for predicting being implemented to predict the quantity of each printing product necessary for printing pages in their natural order, it includes means for updating after each series of predictions concerning a page the quantity of each printing product which would actually be available in each tank, means for checking (406) after each update whether at least several tanks are almost empty and means for sending a message (408) , indicating the need to change or fill tanks.  24-Device according to claim 23, characterized in that it comprises means for memorizing the predicted quantities of products consumed for each page, during processing of the pages in their natural order, with a view to a possible need for selection.  25-Device according to claim 24, characterized in that it comprises means for predicting the quantity of each printing product necessary to print the remaining pages and means for storing them, when a selection is decided.  26-Device according to all of claims 24 and 25, characterized in that said means for searching for a selection comprises means for searching for a subgroup of pages (620) whose printing would result in at least several reservoirs are almost empty after printing these pages.  27-Device according to one of claims 22 to 26, characterized in that it comprises means for predicting said quantity of such a product necessary for the printing of such a page, comprising means for describing this page by pixels (4) and means for counting (6) the lit pixels corresponding to said print product.  28-Device according to claim 27, characterized in that it comprises means for creating a table (Ta, Tb, Tc, Td) describing at least part of a monochromatic component of said document, said component corresponding to said product of printing and each cell of said table representing a pixel, means for counting the number of pixels lit in this table and means for deducing a necessary quantity of the aforementioned corresponding printing product.  29-Device according to claim 28, characterized in that it comprises an aforementioned table of limited capacity, less than the capacity necessary to describe said monochromatic component of said page, means for successively registering groups of pixels of said monochromatic component of said page, means for counting each time the number of lit pixels until all of said monochromatic component of said page has been entered in said table and its lit pixels have been counted (FIG. 3).  30-Device according to claim 29, characterized in that it comprises means for creating each table of limited capacity from digital data representative of adjacent bands of said page.  31-Device according to claim 30, characterized in that it comprises means for selecting overlapping enlarged bands, means for creating at least one enlarged table (103) from the corresponding digital data allowing image reprocessing involving a modification of the lit pixels, means for modifying said table by applying a known correction algorithm (111) and means for removing from the accounting the lit pixels corresponding to the excess part of said enlarged table.  32-Device according to claim 31 for color printing, characterized in that it comprises means for creating as many enlarged tables (103) as there are printing products, each describing a monochromatic component of said page, means for applying, in a manner known per se, a correction algorithm (111) to all the tables and means for separately carrying out the counting of the lit pixels of each table for the prediction of the different quantities of the printing products required, of all relevant colors.  33-Device according to one of claims 28 to 30, characterized in that it comprises calculation means for multiplying (10) the number of pixels lit by a value representing an elementary quantity of said printing product.  34-Device according to claim 33 for an inkjet printing system, characterized in that said value represents the volume of a drop of ejected print product.  35-Device according to claim 34, characterized in that it comprises means for preselecting said value according to predetermined parameters, such as, for example, the type of printer (7) and / or the type of cartridge (8 ) and / or the type of printing product (9).  36-Device according to claim 35, characterized in that it comprises storage means for storing a set of such values and means for selecting one of them according to an effective combination of such parameters.  37-Device according to one of claims 22 to 36, characterized in that said means for measuring an amount of product actually available comprises a capacitive branch including said reservoir (312a, 312d), means for applying an alternating signal (317) to this capacitive branch and means for analyzing a resulting signal (315) in order to deduce therefrom said quantity of printing product actually available.