Patent Publication Number: US-7912396-B2

Title: Printer and duplex printing mode controlling method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Korean Application No. 2005-55916, filed Jun. 27, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     An aspect of the present invention relates to a printer and a duplex printing mode controlling method thereof, and, more particularly, to a printer that shortens printing time by temporarily canceling a duplex printing mode, which is an operational mode to perform printing on both sides of paper, when an amount of print data requiring one side of one piece of paper is inputted into a printer that is preset in the duplex printing mode, and a duplex printing mode controlling method thereof. 
     2. Description of the Related Art 
     Although conventional printers output paper with data printed on one side only, advancing printer technology and user&#39;s demands call for development of printers capable of performing printing on both sides, i.e., duplex printing.  FIG. 1  is a cross-sectional view showing a conventional laser beam printer having a duplex printing capability. As shown in the drawing, the main body  10  of the laser beam printer having a duplex printing function includes a printing path  9  to print an image on paper, an ejecting path  16  to eject printed paper, and a reversing path  20  to reverse the printed paper for duplex printing. 
     Herein, a pickup roller  12 , a feeding roller  13 , and a printing unit  14 ,  15 ,  18  and  19  are disposed at the printing path  9 . The pickup roller  12  picks up paper in a paper supplying cassette  11 , and the feeding roller  13  feeds the paper picked up by the pickup roller  12  into the printing unit  14 ,  15 ,  18  and  19 . The printing unit  14 ,  15 ,  18  and  19  is formed of different constitutional elements according to the kind of a printer. Where a laser beam printer is used, the printing unit is formed of a laser scanner  14 , a developer  18 , a photosensitive drum  19 , and a fixing roller  15 . 
     An ejection roller  17  to eject paper from the apparatus is disposed on the ejecting path  16  at an end thereof. The ejection roller  17  also reverses the driving direction under the control of a controller (not shown) to have the ability to transfer the paper in an ejection direction or toward the beginning of the reversing path  20 . 
     Several pairs of transfer rollers  22  to guide paper to the feeding roller  13  are disposed on the reversing path  20 . 
     The operation of a printer having the above-described structure and the duplex printing capability will now be described. When a duplex printing mode is set up and print data is inputted into the printer by a user terminal, rollers as well as the printing unit  14 ,  15 ,  18  and  19  are operated. A sheet of paper is picked up by the pickup roller  12  and then transferred to the printing unit  14 ,  15 ,  18  and  19  by the feeding roller  13 . An image is developed on one side of the paper by the developer  18  and the photosensitive drum  19  of the printing unit  14 ,  15 ,  18  and  19 , and the image is fixed on the paper by the fixing roller  15 . Then, when the paper is ejected by the ejection roller  17 , except for one end part of the paper which remains inside the apparatus, the rotation direction of the ejection roller  17  is reversed and the paper is inputted into the reversing path  20 . The paper, inputted to the reversing path  20 , is then supplied to the feeding roller  13  by the transfer roller  22 . There, the paper is supplied to the printing unit  14 ,  15 ,  18  and  19  again and an image is developed and fixed on the other side of the paper, which is then ejected from the apparatus by the ejection roller  17 . 
     When the duplex printing mode is set up and an amount of print data requiring one side of one piece of paper is to be outputted, only one side of each piece of paper needs to be printed on. However, the conventional printers perform single-sided printing in the same manner as duplex printing, i.e., ejecting part of the paper, inputting the partially ejected paper into the reversing path  20 , and printing print data on the second side of the paper. Therefore, where single-sided printing is required, the printing operation takes an excessive amount of time. This is because, although printing may be carried out through the printing path  9  and the ejection path  16 , the paper is inputted again into the reversing path  20  and passes through the printing path  9  and the ejection path  16  unnecessarily. Moreover, since the transfer roller  22 , the feeding roller  13 , the fixing roller  15  and the ejection roller  17  should be operated while the paper is inputted into the printer again through the reversing path  20  and passes through the printing path  9  and the ejecting path  16 , power consumption is increased and the life span of the printer is shortened. These problems also occur when the last side of a last page of print materials having an odd total number of side of pages is printed. 
     To prevent the above and/or other problems from occurring, when single-sided printing is required, a print option setup window may be activated or the print mode may be switched into a normal printing mode by manipulating menu buttons in the main body of the printer. However, since a user has to go through several selection processes to activate the print option setup window or find a corresponding print setup menu by manipulating menu buttons in the main body of the printer, such solutions are quite troublesome. 
     Therefore, a method that improves a printing speed by temporarily canceling the duplex printing mode and performing printing in the normal printing mode when the duplex printing mode is set up and a single-sided printing operation or the last page of print materials whose total number of side of pages is an odd number is printed should be sought. 
     SUMMARY OF THE INVENTION 
     The present invention has been developed in order to solve the above drawbacks and/or other problems associated with the conventional arrangement. 
     It is, therefore, an aspect of the present invention to provide a method that can improve a printing speed by temporarily canceling a duplex printing mode and performing printing in a normal printing mode when the duplex printing mode is set up and an amount of print data requiring one side of one piece of paper or the last side of a past piece of paper of print data requiring an odd number of total sides of pieces of paper are printed, and a duplex printing controlling method thereof. 
     In accordance with an aspect of the present invention, the foregoing and/or other objects and advantages are substantially realized by providing a printer, including a printing unit to print print data on print medium. The printer includes a memory to temporarily store the print data supplied from a user terminal, a controller to temporarily cancel a duplex printing mode of the printer and to control the printing unit to print the print data in a normal printing mode, when the duplex printing mode is preset and a quantity of the print data temporarily stored in the memory is within a range of predetermined quantities, a printing path along which the paper is provided to the printing unit so as to have an image printed on a first side thereof, an ejecting path along which the pieces of print media, having had the image printed on the first sides thereof, are ejected from the printer in the normal printing mode, or are partially ejected from the printer in the duplex printing mode, and a reversing path to convey the print medium from the partly ejected position of the ejecting path and toward a beginning of the printing path to position the print medium to be conveyed along the printing path so as to have another image printed on a second side thereof. 
     In accordance with another aspect of the present invention, the foregoing and/or other objects and advantages are substantially realized by providing a method to control a duplex printing mode in a printer, comprising setting the printer in a duplex printing mode, receiving print data; temporarily storing the print data in a memory, determining a number of sides of pieces of paper required for printing based on a quantity of the print data, temporarily canceling the duplex printing mode in favor of a normal printing mode, when the quantity of the print data is a predetermined quantity, and printing the print data in the normal printing mode. 
     Additional and/or other aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a cross-sectional view showing a conventional laser beam printer having a duplex printing capability; 
         FIG. 2  is a block diagram illustrating a laser beam printer in accordance with an embodiment of the present invention; and 
         FIG. 3  is a flowchart describing a duplex printing process in a laser beam printer in accordance with another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures. 
       FIG. 2  is a block diagram illustrating a laser beam printer in accordance with an embodiment of the present invention. As illustrated in the drawing, the laser beam printer includes a printing unit  140 , a roller unit  150 , a sensor unit  120 , a memory  130  and a controller  110 .  FIG. 1  shows a printing path  9 , along which an image is printed onto paper, an ejecting path  16  along which the printed paper is ejected from the printer, and a reversing path  20  to allow for a reversing of the paper for duplex printing, i.e., printing on both sides of the paper. 
     The printing unit  140  includes a laser scanner  141 , a developer  143 , a photosensitive drum  145 , and a fixing roller  147 . The laser scanner  141  scans the photosensitive drum  145  with a laser when print data is provided from a user terminal. The laser-scanned photosensitive drum  145  comes to have an electric potential. The developer  143  develops toner on the photosensitive drum  145 , which transfers the developed toner onto paper. The fixing roller  147  fixes the toner transferred onto paper with heat and pressure. 
     The roller unit  150  includes a pickup roller  112 , a feeding roller  113 , an ejection roller  155 , and a transfer roller  157 . The pickup roller  112  picks up paper in a paper supplying cassette, and the feeding roller  113  feeds the paper picked up by the pickup roller  112  into the printing unit  140 . The ejection roller  155  reverses a driving direction of the ejection roller  155  under the control of the controller  110 , which will be described later, to transfer the paper toward an ejection direction or toward the beginning of the reversing path  20 . The transfer roller  157  is positioned in the reversing path  20  and guides the paper to the feeding roller  113 . 
     The sensor unit  120  includes a paper supply sensor  121  and a paper ejection sensor  123 . The paper supply sensor  121  is set up proximate to the paper supply cassette and senses whether paper is picked up by the pickup roller  112 . The paper ejection sensor  123  is set up proximate to the ejection roller  155  and senses whether paper is ejected and how much of a part of the paper is ejected. 
     The memory  130  temporarily stores print data provided from a user terminal, and determines how many sides of pieces of paper the print data will require based on the quantity of the print data stored in the memory  130 . The print data stored in the memory  130  is outputted in a First-In First-Out (FIFO) method with respect to each sheet of paper, both sides of which are to be printed on during duplex printing. The sides of each one sheet of paper are printed in a Last-In First-Out (LIFO) method. In other words, when print data of a hypothetical document having pages 1 to 4, pages 1 and 2 are inputted prior to pages 3 and 4 based on the FIFO method. For each of the pages 1 and 2, during duplex printing, page 2 is printed prior to page 1 based on the LIFO method. 
     The controller  110  controls the printing unit  140  and the rollers based on information inputted from the sensor unit  120  and the memory  130 . In the duplex printing mode, when the controller  110  determines that paper has passed through the ejection roller  155  except for the one end part of the paper based on a sensing result obtained in the ejection sensor  123 , the controller  110  rotates the ejection roller  155  in a reverse direction to input the paper into the reversing path  20 . In the duplex printing mode, the controller  110  determines how many sides of pieces of paper the print data will require based on the quantity of the print data stored in the memory  130 . As a result of the determination, if the total number of sides of pieces of paper of the print data is one side of one piece of paper or an odd number of sides of paper with one side of one piece of paper remaining to be printed, the controller  110  temporarily cancels the duplex printing mode. In short, when the quantity of print data requires printing on one side of one piece of paper, the controller  110  temporarily cancels the duplex printing mode to prevent the ejection roller  155  from rotating in the reverse direction during the ejection of the paper and to prevent the paper from being inputted unnecessarily into the reversing path  20 . When the total number of sides of sides of pieces of paper is an odd number, the controller  110  performs printing in the duplex printing mode except for when the printing is done on the last side of the last piece of paper. Then, when the last side of the last piece of paper is printed, the controller  110  cancels the duplex printing mode to prevent the paper from circulating unnecessarily through the reversing path  20 . 
     A duplex printing process in the printer having the above-described structure will be described hereafter with reference to  FIG. 3 . First, in operation  200 , a duplex printing mode is set up in a user terminal or a printer. When print data is provided from the user terminal in operation  210 , the controller  110  temporarily stores the print data in the memory  130  in operation  220  and operates the printing unit  140  and the pickup roller  112  and the feeding roller  113  of and the roller unit  150 . Then, the controller  110  determines in operation  230  how many sides of pieces of paper the print data requires based on the quantity of the print data stored in the memory  130 . 
     When the quantity of print data requires more than one piece of paper, whether the number of sides of pages, required by the print data, is an odd number or an even number is determined in operation  240 . If the number of sides of pieces of paper required by the print data is an even number, the controller  110  outputs the print data in the duplex printing mode in operation  270 . That is, if the total number of pieces of paper required by the print data is four (4), the controller  110  provides pages 1 and 2 to the printing unit  140  first based on the FIFO method when the controller  110  prints out the print data stored in the memory  130 , and the controller  110  provides page 2 prior to page 1 among pages 1 and 2 by applying the LIFO method. This way, the print data of page 2 is printed first on one side of the paper transferred to the printing unit  140 . Subsequently, the controller  110  ejects the paper except for a part of the paper using the ejection roller  155  and when the controller  110  determines that a predetermined part of the paper is, the controller  110  rotates the ejection roller  155  in a reverse direction and supplies the paper to the feeding roller  113  through the reversing path  20 . The print data of the page 1 is then printed on the other side of the paper supplied to the printing unit  140  through the feeding roller  113 , and the paper having had both sides printed on is ejected from the printer by the ejection roller  155 . 
     Meanwhile, when the quantity of printed data stored in the memory  130  requires one side of one piece of paper, the controller  110  temporarily cancels the duplex printing mode in the operation  270  and prints the print data in the normal printing mode in operation  290 . In short, the controller  110  supplies the print data, requiring one side of one piece of paper, from the memory  130  to the printing unit  140 , which prints the one side of one page print data on a sheet of paper. When the printing is completed, the controller  110  drives the ejection roller  155  and ejects the paper transferred through the ejecting path directly to the outside. 
     Also, when the quantity of print data stored in the memory  130  requires an odd number of sides of pieces of paper, in other words, when the total number of pieces of paper required by the print data quantity is an odd number, the controller  110  performs printing in the duplex printing mode up to the last even numbered piece of paper in operation  250  and temporarily cancels the duplex printing mode and performs the printing in the normal printing mode in operation  290  when the last side of the last piece of paper remains to be printed. 
     As is described above, in accordance with aspects of the present invention, a user need not change the setup of the normal printing mode of a printer by manipulating a menu of the printer or a print option setup window, because the printer temporarily cancels the duplex printing mode when print data requiring one side of one piece of paper is inputted or the total pages required by the print data is an odd number when the print is preset in the duplex printing mode. In such printing operations, each piece of paper need not be inputted into the reversing path  20  and then passed through the printing path  9  and the ejecting path  16  again. Therefore, providing users with convenience, shorten printing times, and lengthen the life spans of printers by relieving the printer from wasteful operations is possible. 
     Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.