Patent Publication Number: US-6714316-B1

Title: Image forming apparatus, image forming system, computer-readable record medium stored with image forming program, and image forming method

Description:
This application is based on Japanese Patent Application No. 10-268134 filed on Sep. 22, 1998, the contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to image forming apparatuses such as copying machines and printers, an image forming system for printing an image data outputted by a computer, and a computer-readable record medium stored with an image forming program for computers, printers or copying machines. 
     2. Description of the Related Art 
     Some of the image forming apparatuses represented by printers and copying machines are equipped with a large capacity storage device such as a hard disk device. The storage device is used for temporarily storing an image data before they are printed on paper. 
     Those image forming apparatuses are normally equipped with a tray for collecting papers after printing. It happens in some cases that the number of pages required for printing all the data stored in the storage device exceeds the capacity of such a tray. In such a case, the printing action of the image forming apparatus may stop short of printing the entire stored image data, or worse, may cause a paper jam condition in the mechanism used for discharging the printed paper. 
     SUMMARY OF THE INVENTION 
     It is a general object of the invention is to make it possible to print an entire image data even if the number of sheets necessary for printing the entire image data exceeds the capacity of the tray. 
     Another object of the invention is to provide an image forming apparatus including a receiving unit for receiving a printing job that includes image data, a counting unit for counting a number of sheets required by the printing job when an image for one page is formed on a sheet of paper, an image forming unit for forming images for a plurality of pages on a sheet of paper when the number of sheets exceeds a prescribed value, and a tray for receiving an image formed sheet. 
     Another object of the invention is to provide an image forming system including a printer for printing an image data, and a computer for preparing the image data. The computer includes a counting means for counting a number of sheets required by prepared image data when an image for one page is formed on a sheet of paper, an image preparing means for newly preparing image data for forming images for a plurality of pages on a sheet of paper when the number of sheets exceeds a prescribed value, a job preparing means for preparing a printing job containing the newly prepared image data, and a transmitting means for transmitting the printing job to the printer. 
     Another object of the invention is to provide a record medium stored in a computer-readable manner a program to be executed by the computer for printing an image data on a paper. The program includes the steps of (A) acquiring a number of sheets required by prepared image data when an image for one page is formed on one sheet of paper, (B) newly preparing image data for forming images for a plurality of pages on a sheet of paper when the number of sheets exceeds the prescribed value, (C) preparing a printing job including the newly prepared image data, and (D) transmitting the printing job to a printer. 
     Another object of the invention is to provide an image forming method includes the steps of (A) receiving a printing job including image data, (B) acquiring a number of sheets required for a printing job when an image for one page is formed on a sheet of paper, (C) forming images for a plurality of pages on a sheet of paper when the number of sheets exceeds the prescribed value, and (D) discharging an image formed sheet to a tray. 
    
    
     The objects, characteristics, and advantages of this invention other than those set forth above will become apparent from the following detailed description of the preferred embodiments, which refers to the annexed drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross section of a printer according to the first embodiment of the present invention; 
     FIG. 2 is a block diagram of a controller of the printer; 
     FIG. 3 is a flow chart of a processing sequence of the printer; 
     FIG. 4 is a display example for selecting a job to be printed; 
     FIG. 5 is a display example of reduction candidates; 
     FIGS.  6 ( a ) and  6 ( b ) are a flow chart of processing sequence for displaying reduction candidates; 
     FIG. 7 is a flow chart of a processing sequence of a printer according to the second embodiment of the present invention; 
     FIG. 8 is a list showing a priority of the reduction process; 
     FIG. 9 is a block diagram of a computer system according to the third embodiment of the present invention; and 
     FIG. 10 is a flow chart of a printing process sequence. 
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The embodiments of this invention will be described below with reference to the accompanying drawings. 
     Embodiment 1 
     The image forming apparatus  1  shown in FIG. 1 is an electrophotographic type printer containing a hard disk device for temporarily storing an image data received from external equipment such as a computer and a tray  17  for storing paper to be discharged after printing. The printer  1  is capable of printing an entire stored image data by executing a reduction process. As described in detail later, the reduction process is composed of printing the image data for a plurality of pages on a single sheet of paper, when the number of sheets required for printing the entire stored image data or the image data for the entire pages of the particular document exceeds the capacity of the tray  17 . 
     Now, the mechanical structure of the printer  1  is described in outline. 
     The printer  1  includes a photoconductor drum  11  on which a latent electrostatic image is formed, an illuminating unit  12  for forming the latent electrostatic image on the photoconductor drum  11 , a paper cassette  13  in which papers are stored for image forming, a transferring charger  14  for transferring the latent electrostatic image on the photoconductor drum  11  to the paper, a fixing unit  15  for fixing the image transferred onto the paper, a discharging roller pair  16  for discharging the paper after fixing, the tray  17  for collecting the discharged paper, and a pair of a transporting roller  21  and a transporting belt  22  for transporting the paper in the paper cassette  13  to the discharging roller pair  16  via the photoconductor drum  11  and the fixing unit  15 . The illuminating unit  12  includes such a device as a semiconductor laser or a light emitting diode (LED). 
     The printer  1  further includes a double-side unit  23  for turning over the paper discharged from the discharging roller pair  16  for the purpose of double-side printing, and a transporting passage  24  for transporting the turned-over paper again to the photoconductor drum  11 . It also has a sensor  18  in the vicinity of the tray  17 . The sensor  18  has a function of counting the number of sheets of paper discharged or collected on the tray  17  and the function of detecting whether there are any sheets on the tray  17 . On the top side of the printer  1 , an operating panel  19  is provided to display various inputs and various messages required for the printer  1 . The operating panel  19 , for example, consists of a liquid crystal touch panel. 
     Now, the controller of the printer  1  is described referring to FIG.  2 . 
     The controller includes a CPU  101  for executing a prescribed program, a ROM  102  for storing the prescribed program, a RAM  103  to be used as a working area used by the CPU  101  for expanding data in the execution of the program, an interface  104  for exchanging the necessary data such as an image data with the external computer, a hard disk device  105  for storing received image data, and an image processing unit  106  for executing various image processes such as a process for reducing/enlarging an image for printing, 2in-1 process, or 4-in-1 process. These parts are connected to lines. The 2-in-1 process is an image process for printing image data that corresponds to two pages on one side of a sheet of paper. The 4-in-1 process is an image process for printing image data that corresponds to four pages on one side of a sheet of paper. 
     Furthermore, the controller is connected to the operating panel  19  via a line, while it is also connected to various printer parts such as the photoconductor drum  11 , the illuminating unit  12 , the fixing unit  15 , the sensor  18 , a drive source for the transporting roller  21  and transporting belt  22 , and the double-side unit  23  via I/O port  107 . 
     Now, the operations of the printer after the image data that has been received from external equipment such as a computer is stored in the hard disk device  105  is described referring to FIG.  3 . 
     First of all, when the printing button on the operating panel  19  is depressed, printing is enabled (step S 1 ). It is also possible to keep the printing always enabled and advance the process to the step S 2  at a point when the image data received from external equipment such as a computer is stored on the hard disk device  105 . 
     Next, a job to be printed is selected from among the jobs currently stored on the hard disk device  105  (step S 2 ). More specifically, when the printing button is depressed, a printing job list will be displayed on the operating panel  19  of the printer  1  as shown in FIG. 4, and the user specifies a job to be printed from the list. Without recourse to manual input operation, the selection of the job can also be done in the order of storage to start printing, automatically. 
     Next, the current capacity of the tray  17  is calculated (step S 3 ). The current capacity of the tray  17  is obtained by reducing the number of sheets currently existing on the tray  17  from the preset initial capacity of the tray  17 . The number of sheets existing on the tray  17  is calculated from the height of paper stacked on the tray  17  to be detected by the sensor  18 . 
     Next, the number of sheets required for printing the selected job under normal printing is compared with the current capacity of the tray  17  (step S 4 ). The normal printing means printing an image data equivalent to a page of the document on one side of a sheet of paper. If it is ascertained that the number of sheets required for the normal printing does not exceed the current capacity as a result of the comparison of the step S 4 , the image data is printed in its entirety (step S 5 ) to end the process. 
     If it is judged that the number of sheets to be printed exceeds the current capacity as a result of the step S 4 , reduction candidates will be displayed on the operating panel  19  (step S 6 ). The reduction candidates include various forms that enable to output the entire image data by printing the image data for a plurality of pages on a single sheet of paper. The displayed items are typically messages and forms of reduction processes as shown in FIG.  5 . The messages mainly include the content indicating that the number of sheets required for printing the entire image data exceeds the capacity of the tray when the normal printing is executed. 
     In case of an example shown in FIG. 5, the formats of the reduction process are double-side 2-in-1, 4-in-1 process, and double-side 4-in-1 process as the reduction candidates for printing the entire image data, or 1-in-1 process, double-side process, and 2-in-1 process as the reduction candidates for printing a portion of the image data or the image data for the first page through a certain page of the document. The double-side 2-in-1 process is an image process for printing image data equivalent to four pages on two sides of a single sheet of paper or two pages of image per side. The double-side 4-in-1 process is an image process for printing image data equivalent to eight pages of the document on two sides of a single sheet of paper or four pages of image per side. The 1-in-1 process is a normal image process for printing without using the reduction process or the double-side printing technique. 
     Next, the user selects one of the displayed reduction candidates as needed (step S 7 ). The printing is then executed according to the selected reduction process, and the printed paper is discharged to the tray  17  (step S 8 ). 
     For example, when the 2-in-1 process is selected at the step S 7 , image data equivalent to two pages are read from the hard disk device  105  and reduced by the image processing unit  106  of the controller so that they can be printed on one side of a single sheet of paper. After that, the image data equivalent to two pages are printed on one side of a sheet of paper and the sheet is discharged. 
     If the double-side process is selected at the step S 7 , an image data equivalent to one page of the document is read from the hard disk device  105  to be printed on one side of a sheet of paper, and, after the sheet is turned over by the double-side unit  23 , an image data for the next one page is read from the hard disk  105  to be printed on the other side of the sheet. The sheet printed with the image corresponding to one page on each side is then discharged. 
     Now, the display procedure of the reduction candidates at the step S 6  is described in detail referring to FIG.  6 . 
     First, the number of sheets required for the normal printing of the document and the current capacity of the tray are set as the variable A and the variable B, respectively (step S 61 ). 
     Next, a decision is made as to whether the double-side unit is provided (step S 62 ). The step S 62  is provided to apply on a printer having no double-side unit a process similar to that of a printer having a double-side unit. 
     When it is ascertained at the step S 62  that the particular printer is equipped with a double-side unit, one half of the number of sheets required for the normal printing is compared with the current capacity of the tray (step S 71 ). 
     If it is determined that it is possible to print the entire image data by reducing the number of sheets required for printing to one half at the step S 71 , the double-side process, the 2-in-1 process, the double side 2-in-1 process, the 4-in-1 process and the double side 4-in-1 process will be displayed as the reduction candidates, while the 1-in-1 process will be displayed as the reduction candidate for printing a portion of the image data (step S 72 ). 
     If it is determined that it is impossible to print the entire image data even if the number of sheets required for printing is reduced to one half at the step S 71 , one quarter of the number of sheets required for the normal printing is compared with the current capacity of the tray (step S 73 ). 
     If it is determined that it is possible to print the entire image data by reducing the number of sheets required for printing to one quarter at the step S 73 , the double-side 2-in-1 process, the 4-in-1 process and the double side 4-in-1 process will be displayed as the reduction candidates, while the 1-in-1 process, the double-side process and the 2-in-1 process will be displayed as the reduction candidates for printing a portion of the image data (step S 74 ). 
     If it is determined that it is impossible to print the entire image data even if the number of sheets required for printing is reduced to one quarter at the step S 73 , one eighth of the number of sheets required for the normal printing is compared with the current capacity of the tray (step S 75 ). 
     If it is determined that it is possible to print the entire image data by reducing the number of sheets required for printing to one eighth at the step S 75 , the double-side 4-in-1 will be displayed as the reduction candidate, while the 1-in-1 process, the double-side process, the 2-in-1 process, the double-side 2-in-1 process and the 4-in-1 process will be displayed as the reduction candidates for printing a portion of the image data (step S 76 ). 
     If it is determined that it is impossible to print the entire image data even if the number of sheets required for printing is reduced to one eighth at the step S 75 , the system displays a message that the entire image data cannot be printed even with the reduction process, and the 1-in-1 process, the double-side process, the 2-in-1 process, the double-side 2-in-1 process, the 4-in-1 process and the double-side 4-in-1 process will be displayed as the reduction candidates for printing a portion of the image data (step S 77 ). 
     On the other hand, if it is ascertained at the step S 62  that the particular printer is not equipped with a double-side unit, one half of the number of sheets required for the normal printing is compared with the current capacity of the tray (step S 81 ). 
     If it is determined that it is possible to print the entire image data by reducing the number of sheets required for printing to one half at the step S 81 , the 2-in-1 process and the 4-in-1 process will be displayed as the reduction candidates, while the 1-in-1 process will be displayed as the reduction candidate for printing a portion of the image data (step S 82 ). 
     If it is determined that it is impossible to print the entire image data even if the number of sheets required for printing is reduced to one half at the step S 81 , one quarter of the number of sheets required for the normal printing is compared with the current capacity of the tray (step S 83 ). 
     If it is determined that it is possible to print the entire image data by reducing the number of sheets required for printing to one quarter at the step S 83 , the 4-in-1 process will be displayed as the reduction candidate, while the 1-in-1 process and the 2-in-1 process will be displayed as the reduction candidates for printing a portion of the image data (step S 84 ). 
     If it is determined that it is impossible to print the entire image data even if the number of sheets required for printing is reduced to one quarter at the step S 83 , the system displays a message that the entire image data cannot be printed even with the reduction process, and the 1-in-1 process, the 2-in-1 process, and the 4-in-1 process will be displayed as the reduction candidates for printing a portion of the image data (step S 85 ). 
     The symbols ◯, Δ and X used at the steps S 72 , S 74 , S 76 , S 77 , S 82 , S 84  and S 85  shown in FIG. 6 represent respectively the reduction candidate that enables full printing, the reduction candidate that enables partial printing, and the reduction candidate that is not displayed as it is a function not provided by the particular printer. 
     As seen in the above, when the number of the sheets required for printing the entire image data received from external equipment such as a computer and temporarily stored on the hard disk device  105  exceeds the capacity of the tray  17 , the printer  1  can print the entire image data by executing a reduction process specified by the user to print out the image data for a plurality of pages on a sheet of paper. Moreover, since the printer  1  is equipped with the sensor  18  that detects the number of sheets stacked on the tray  17 , the system can determine the current capacity of the tray  17 . Therefore, even if a certain amount of printed sheets are already stacked on the tray  17 , and the number of sheets that can be discharged is small, it still may be able to print the entire image data without exceeding the capacity of the tray  17 . 
     Embodiment 2 
     In the first embodiment, the user selects the reduction process when the number of sheets required for printing the entire image data exceeds the capacity of the tray. On the other hand, the reduction process is automatically executed according to the prescribed priority in the second embodiment. The descriptions of the function and structure of the printer similar to those of the first embodiment will be omitted. 
     Now, the operations of the printer  1  after an image data received from external equipment such as a computer is stored in the hard disk device  105  is described referring to FIG.  3 . 
     First, when it is ascertained that the storing process of the image data is completed at the step S 11 , the current capacity of the tray  17  will be calculated (step S 12 ). The current capacity of the tray  17  is obtained by reducing the number of sheets currently existing on the tray  17  from the preset initial capacity of the tray  17 . The number of sheets existing on the tray  17  is calculated from the height of papers stacked on the tray  17  to be detected by the sensor  18 . 
     Next, the number of sheets required for printing the job stored on the hard disk device  105  under normal printing is compared with the current capacity of the tray  17  (step S 13 ). If a plurality of jobs are stored in the hard disk device  105 , this comparison is applied to a job with the highest priority. 
     If it is ascertained that the number of sheets required for the normal printing does not exceed the current capacity of the tray  17  as a result of the comparison of the step S 13 , the image data is printed in its entirety (step S 14 ) to end the process. 
     If it is judged that the number of sheets to be printed exceeds the current capacity as a result of the comparison at the step S 13 , a reduction candidate for printing an entire image data will be selected based on the prescribed priority (step S 15 ). 
     The priority for the reduction processes as used is stored in the hard disk device  105  in the list format shown in FIG.  8 . The double-side printing shown in the list of FIG. 8 will be omitted if the particular printer is not equipped with a double-side unit  23 . The list is prepared by extracting the reduction candidates for printing the entire image data as an internal process in advance, and it is similar to the procedure for displaying the reduction candidates shown in FIG. 6 in relation to the first embodiment. 
     Next, printing is executed according to the selected reduction process and the sheets are discharged to the tray  17  (step S 16 ). 
     As seen in the above, when the number of the sheets required for printing the entire image data received from external equipment such as a computer and stored on the hard disk device  105  exceeds the capacity of the tray  17 , the printer according to the second embodiment can automatically select the reduction process, print the entire image data, and discharge the printed sheets. 
     In both the first and second embodiments, the program pre-stored on the printer ROM  102  is executed based on the CPU  101  to implement the above procedures. Specifically, the CPU  101 , ROM  102 , and RAM  103  function as the means of comparison and control during execution of the program. The printing means consists of the printer internal members such as the photoconductor drum  11 , the illuminating unit  12 , and the fixing unit  15 , as well as the members on the transport passage such as the transporting roller  21  and the transporting belt  22 . The reduction process means consists of the image processing unit  106  and the double-side unit  23 . 
     The first and second embodiments are applicable to printers, which are capable of expanding their functions by means of installing application software provided by the computer readable record medium. Specifically, the above-described process can be implemented by that the CPU  101  executes the program provided by the record medium and installed on the hard disk device  105  and the RAM  103 , instead of the program stored on the ROM. 
     The printers according to the first and the second embodiments have an image forming mechanism that is similar to those of copying machines and facsimile machines. Therefore, the above-described process can be easily applied to copying machines and facsimile machines. 
     In case of a copying machine, an image data read by an image reading device provided on the copying machine is used instead of an image data transmitted by external equipment such as a computer. Once the image data is stored on a storage device of the copying machine such as a hard disk or an image memory, a procedure similar to the one described above is executed. As a result, the number of sheets to be discharged on a tray of the copying machine is not going to exceed the capacity of the tray so that the entire document is going to be properly copied. 
     A facsimile machine uses an image data received via communication lines such as public telephone lines from a communication unit that sends or receives an image data. Once the image data is stored in a hard disk device of the facsimile machine, a procedure similar to the one described above is executed. As a result, the number of sheets to be discharged on a tray of the facsimile machine is not going to exceed the capacity of the tray so that an entire image data is going to be properly printed. 
     Embodiment 3 
     The image forming system shown in FIG. 9 is a computer system, a kind of a LAN system, which consists of a printer  300  and a plurality of computers  200  connected to each other via a network channel  400 . An image data prepared and/or edited by the computer  200  is transmitted to the printer  300  for printing. The reduction process is executed by the computer  200  in order to make the number of sheets required for printing an entire image data not to exceed a capacity of a tray provided in the printer  300 . 
     Since this kind of computer system has been widely in use, the description of the computer and the printer&#39;s hardware composition is omitted. Also, although the drawing shows only one printer, the invention is applicable to an image forming system having a plurality of printers. 
     Now, the control sequence for printing using the computer  200  is described referring to FIG.  10 . 
     When the preparation and/or editing of the image data consisting of documents and graphics using the application software of the computer  200  are completed, the printing instruction will be issued (step S 101 ). 
     Next, a printer driver is activated (step S 102 ), and the status of the printer  300  such as the capacity of the tray and the presence of the double-side unit, is inquired (step S 103 ). 
     If a sensor (refer to the sensor  18  of the first embodiment) is provided to detect the number of sheets stacked on the tray of the printer  300 , the capacity of the tray sent from the printer  300  represents the current value. If the printer  300  does not have a function of sending the capacity of the tray as the status, it is possible to use a predetermined value, for example, the initial capacity unique to the particular tray. 
     Next, the capacity of the tray or the received data is set (step S 104 ), and the number of the sheets required for printing the entire image data is compared with the capacity of the tray (step S 105 ). 
     If the number of sheets required for the printing does not exceed the capacity of the tray as a result of the comparison at the step S 105 , the normal processes, i.e., the rasterizing and spooling processes are executed and the image data is transmitted to the printer  300  when the job acceptance at the printer  300  is approved (step S 106 ). 
     If the number of sheets required for the printing exceeds the capacity of the tray as a result of the comparison at the step S 105 , the reduction process is executed by the computer  200  in order to reduce the number of sheets required for the printing (step S 107 ). In the reduction process, the image data for printing is newly prepared by the image processing in order to print the image data for a plurality of pages on a sheet of paper as described before. 
     Specifically, the 2-in-1 process for printing the image data for two pages on one side of the sheet, or the 4-in-1 process for printing the image data for four pages on one side of the sheet is executed. If it is ascertained that a double-side unit exists based on the status information of the printer  300  obtained by the step S 103 , it is possible to execute the double-side process, the double side 2-in-1 process for printing the image data for four pages on two sides of a single sheet or two pages of image per side, or the double side 4-in-1 process for printing the image data for eight pages on two sides of a single sheet or four pages of image per side. 
     The format of the reduction process executed at the step S 107  is automatically selected from the reduction candidates that enable full printing of the image data. The reduction candidates are extracted the same way as in the procedure for the first embodiment shown in FIG.  6 . The automatic selection of the reduction process is appropriately executed, for example, according to the list for the second embodiment shown in FIG.  8 . The selection of the reduction process is possible not only by the automatic method but also by the manual method. For example, as the example shown in FIG. 5, it is possible to show the reduction candidates that enable full printing of the image data and the reduction candidates that enable partial printing of the image data on the display of the computer  200  and let the user to select an appropriate one. 
     Next, the normal processes, i.e., the rasterizing and spool processes of the image data newly prepared by the reduction process are executed by the printer driver and, when the job receiving at the printer  300  is approved, the image data is transmitted to the printer  300  (step S 106 ). If there is an instruction for the double-side printing, it is also transmitted to the printer  300 . 
     As seen in the above, when the image data exists that exceeds the capacity of the tray of the printer, the image data is processed in such a way as to reduce the number of sheets required for the printing and the data thus obtained is transferred to the printer. Therefore, the number of sheets to be discharged will not exceed the capacity of the tray and the entire image data will be printed. 
     The actual process is conducted by the computer  200  executing the program prepared according to the control sequence described above. The program is provided, for example, stored in the record medium that is readable by the computer. Moreover, the program can be provided as independent application software or as a part of the printer driver&#39;s function. 
     It is obvious that this invention is not limited to the particular embodiments shown and described above but may be variously changed and modified by any person of ordinary skill in the art without departing from the technical concept of this invention. 
     The printers according to the first and second embodiments have only one tray  17  for collecting the sheets after printing. However, the present invention is also applicable to a finisher equipped with a plurality of discharge pins. For example, a finisher, which has a plurality of discharge bins and is so designed as to detect current capacities of the discharge bins, can execute the reduction process such as the double-side process, the 2-in-1 process and the 4-in-1 process, when the number of sheets needed for printing exceeds the current capacity of the relevant discharge bin. 
     The image forming system of the third embodiment consists of the printer  300  and a plurality of the computers  200  connected to each other via the network channel  400 , and the printer  300  is directly controlled by the computer  200 . However, the present invention is not construed to be limited to this constitution. It is also applicable to a system having a print server that stores an image data sent from a computer and outputs the image data sequentially to the printer. In such a case, it is constituted in such a way that the print server compares the capacity of the tray with the number of sheets required for the printing and executes the reduction process as needed based on the result of the comparison.