Patent Publication Number: US-2005141050-A1

Title: Method and system to compensate for image size in multifunction printer with scanning function

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application claims the priority of Korean Patent Application No. 2003-97803, filed on Dec. 26, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present general inventive concept relates to a method and apparatus to compensate for an image size in a multifunction printer with a scanning function, and more particularly, to a method and apparatus, which can make a size of a print image of a print document identical to that of an image of an original document by controlling a main motor to adjust a length of the print image and a polygon motor to adjust a width of the print image.  
      2. Description of the Related Art  
      In a multifunction printer with a scanning function, an image size of a print document is not generally identical to that of an original document. This is caused by the interrelation between motors that control a width and a length of the documents.  
      Korean Patent Laid-Open Publication No. 2003-4799 discloses a document magnifying/printing method of a multifunction printer. According to this magnifying/printing method, a left and right ratio and an overall scan ratio with respect to a current scanned area detected by a black patch are compared to provide an accurately magnified scan image. However, this magnifying/printing method does not disclose a control method of main and polygon motors.  
     SUMMARY OF THE INVENTION  
      The present general inventive concept provides a method and apparatus, which can make a size of a print image of a print document identical to that of an image of an original document by controlling a main motor controlling a length of the print image and a polygon motor controlling a width of the print image.  
      Additional aspects and advantages of the present general inventive concept 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 general inventive concept.  
      The foregoing and/or other aspects and advantages of the present general inventive concept are achieved by providing, there is provided an image size compensating system of a multifunction printer, the system comprising a scanning unit to generate scan data obtained by scanning a reference document and a copy of the reference document, a system control unit to extract scan information on widths and lengths of the reference document and the copy from the scan data, and a printer engine to receive the scan information from the system control unit and to control a main motor controlling (adjusting) a length of a print image and a polygon motor controlling (adjusting) a width of the print image so that the sizes of the reference document and the copy are identical to each other.  
      The system control unit may comprise a control unit to generate a motor RPM control command for controlling RPMs of the main and polygon motors based on the scan information on the widths and lengths of the reference document and the copy, and a memory to store the RPMs of the main and polygon motors and to update the RPMs.  
      The control unit may increase or reduce the RPM of the polygon motor first to make the widths of the reference document and the copy identical to each other when the widths and lengths of the reference document are different from those of the copy, considering a length variation of the copy according to an RPM variation of the polygon motor.  
      When the length of the reference document is identical to that of the copy, the control unit may increase the RPMs of the main and polygon motors at a first predetermined rate according to a difference between the widths of the reference document and the copy in a case where the width of the copy is less than that of the reference documents, may reduce the RPM of the main and polygon motors at a second predetermined rate according to the difference between the widths of the reference document and the copy in a case where the width of the copy is greater than that of the reference document, and may maintain the current RPM of the polygon motor in a case where the width of the copy is identical to that of the reference document.  
      When the width of the reference document is identical to that of the copy, the control unit may increase the RPM of the main motor at a third predetermined rate according to a difference between the lengths of the reference document and the copy in a case where the length of the copy is less than that of the reference documents, may reduce the RPM of the main motor at a fourth predetermined rate according to the difference between the lengths of the reference document and the copy in a case where the length of the copy is greater than that of the reference document, and may maintain the current RPM of the polygon motor in a case where the length of the copy is identical to that of the reference document.  
      The printer engine may comprise an engine control unit to receive a motor RPM control command from the system control unit to control the main and polygon motors such that the sizes of the reference document and the copy are identical to each other, the main motor controlling the length of the print image according to the motor RPM control command transmitted from the engine control unit, and a laser scanning unit including the polygon motor controlling the width of the print image according to the motor RPM control command from the engine control unit.  
      The foregoing and/or other aspects and advantages of the present general inventive concept may also be achieved by providing an image size compensating method comprising storing scan information on sizes of a reference document and a copy of the reference document after scanning the reference document and the copy, and compensating an image size by controlling a main motor to adjust a length of a print image and a polygon motor to adjust a width of the print image such that the sizes of the reference document and the copy are identical to each other according to the scan information.  
      The image size compensating method may further comprise identifying if the sizes of the copy and the reference document are identical to each other by scanning the reference document and printing a scanned image of the reference document to make the copy and scanning the copy.  
      The storing of the scan information may comprise storing first scan information on a length and a width of the reference document by scanning the reference document, and storing second scan information on a length and a width of the copy by scanning the copy of the reference document.  
      The compensating of the an image size may comprise controlling RPMs of the polygon and main motors by comparing the width of the reference document with the width of the copy of the reference document, and controlling the RPMs of the polygon and main motors by comparing the length of the reference document with the length of the copy of the reference document.  
      when the length of the reference document is identical to that of the copy, the RPMs of the main and polygon motors may be increased at a first predetermined rate according to a difference between the widths of the reference document and the copy in a case where the width of the copy is less than that of the reference documents, the RPMS of the main and polygon motors may be reduced at a second predetermined rate according to the difference between the widths of the reference document and the copy in a case where the width of the copy is greater than that of the reference document, and the current RPM of the polygon motor may be maintained in a case where the width of the copy is identical to that of the reference document.  
      When the width of the reference document is identical to that of the copy, the RPM of the main motor may be increased at a third predetermined rate according to a difference between the lengths of the reference document and the copy in a case where the length of the copy is less than that of the reference documents, the RPM of the main motor may be reduced at a fourth predetermined rate according to the difference between the lengths of the reference document and the copy in a case where the length of the copy is greater than that of the reference document, and the current RPM of the polygon motor may be maintained in a case where the length of the copy is identical to that of the reference document.  
      The compensating of the image size may further comprise reducing or increasing an RPM of the polygon motor to make the widths of the reference document and the copy identical to each other when the widths and lengths of the reference document are different from those of the copy, considering a length variation of the copy according to an RPM variation of the polygon motor.  
      The RPMs of the main and polygon motors may be updated.  
      The first, second, third, or fourth predetermined rate may be determined by a test or simulation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      These and/or other aspects and advantages of the present general inventive concept 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 block diagram illustrating an image size compensation system according to an embodiment of the present general inventive concept;  
       FIG. 2  is a block diagram illustrating a system control unit of  FIG. 1 ;  
       FIG. 3  is a block diagram illustrating a printer engine of  FIG. 1 ;  
       FIG. 4  is a flowchart illustrating an image size compensating method according to another embodiment of the present general inventive concept;  
       FIG. 5  is a flowchart illustrating a scan information storing operation S 400  of  FIG. 4 ;  
       FIG. 6  is a flowchart illustrating an image size compensating operation S 401  of  FIG. 4 ;  
       FIG. 7  is a flowchart illustrating an identifying operation S 402  of  FIG. 4 ; and  
       FIG. 8  is a schematic view illustrating a position of a reference document to be loaded according to another embodiment of the present general inventive concept. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Reference will now be made in detail to the embodiments of the present general inventive concept, 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 general inventive concept by referring to the figures.  
       FIG. 1  is a block diagram illustrating an image size compensating system according to an embodiment of the present general inventive concept.  
      Referring to  FIG. 1 , an image size compensating system comprises a scanning unit  100 , a system control unit  110 , and a printer engine  120 .  
      The scanning unit  100  scans a document to generate scan data  101  including a width and a length of the document, and transmits the scan data  101  to a system control unit  110 .  
      The system control unit  110  receives the scan data  101  from the scanning unit  100 , extracts information on the width and length of a scanned image of the document from the scan data  101 , controls RPMs of main and polygon motors of the printer engine  120  to adjust an image size of a print document to that of an original document, and transmits video data  111  to the printer engine  120 .  
      The printer engine  120  receives the video data  111  from the system control unit  110 , prints the scanned image by transferring the scanned image to a photo drum using a laser scanning unit, and transmits a beam detect (BD) signal  113  eradiated from the laser scanning unit to the system control unit  110 . The system control unit  110  transmits a motor RPM control command  112  to the printer engine  120  according to the extracted information on the width and the length of the scanned image of the document.  
       FIG. 2  is a block diagram illustrating the system control unit  110  of the image size compensating system of  FIG. 1 .  
      As shown in  FIGS. 1 and 2 , the system control unit  110  comprises a control unit  200 , a memory  210 , and a video data generating unit  220 .  
      The control unit  200  receives the scan data  101  including the width and the length of the scanned image of the document from the scanning unit  100 , generates the motor RPM control command  112  for the main and polygon motors according to the width and the length, transmits the motor RPM control command  112  to the printer engine  120  and the video data  111  to the printer engine  120  through the video data generating unit  220 . The memory  210  stores current RPM values of the main and polygon motors, updates the RPM values in accordance with a difference between an image of the original document and an image of the print document, and stores scan information on an image size of the document scanned by the scanning unit  100 .  
      The video data generating unit  220  receives the scan data  200  from the control unit  200  to generate the video data  111  for controlling the printer engine in an on/off method and transmits the video data  111  to the printer engine  120 .  
       FIG. 3  is a block diagram illustrating the printer engine  120  of  FIG. 1 .  
      Referring to  FIG. 3 , the printer engine  120  comprises a laser scanning unit  300  including the polygon motor, an engine control unit  310 , and the main motor  320 .  
      The laser scanning unit  300  receives the video data  111  from the video data generating unit  220 , prints the scanned image by transferring the same to the photo drum, generates the BD signal  111  in advance of printing a line of dots corresponding to the scanned image, and transmits the BD signal  113  to the system control unit  110 . The polygon motor (not shown) of the laser scanning unit  300  controls the width of the image of the print document according to a first motor control signal  311  transmitted from the engine control unit  310 . The engine control unit  310  receives the motor RPM control command  112  for the main and polygon motors from the control unit  200  and drives the main and polygon motors according to the motor RPM control command.  
      The main motor  320  receives a second motor control command  312  from the engine control unit  310  to control the length of the image of the print document. The main motor  320  may be a motor to drive a document transfer roller or a document feeding roller.  
       FIG. 4  shows a flowchart illustrating an image size compensating method according to another embodiment of the present general inventive concept.  
      The image size compensating method comprises a scan information storing operation S 400 , an image size compensating operation S 401 , and an identifying operation S 402 .  
      In the scan information storing operation S 400 , a reference document and a copy are scanned, and scan information on an image size of the document and the copy are stored. This will be described more in detail later with reference to  FIG. 5 .  
      In the image size compensating operation S 401 , sizes (widths and lengths) of the reference document and the copy are compared with each other, and RPMs of the main and polygon motors are controlled according to the comparison. This will be described more in detail later with reference to  FIG. 6 .  
      In the identifying operation S 402 , the copy is scanned again according to the RPMs of the main and polygon motors, and the compensated results are identified. This will be described more in detail later with reference to  FIG. 7 .  
       FIG. 5  shows a flowchart illustrating the scan information storing operation S 400  of  FIG. 4 .  
      The scan information storing operation S 400  comprises a reference document scan operation S 500 , a reference document scan result storing operation S 501 , a scan result output operation S 502 , a copy scan operation S 503 , and a copy scan result storing operation S 504 .  
      In the reference document scan operation S 500 , the scanning unit  100  scans the reference document to generate scan information including a width and a length of the reference document.  
      In the reference document scan result storing operation S 501 , the scan information of the reference document is stored in the memory  210 . The width and length of the reference document are respectively R 1  and R 2 , and the width and length of the copy are respectively R 3  and R 4 .  
      In the scan result output operation S 502 , the video data of the reference document is generated and a copy of the reference document is printed by transferring the video data to the photo drum using the on/off method.  
      In the copy scan operation S 503 , the scanning unit  100  scans the copy to generate scan information including the width and length of the copy.  
      In the copy scan result storing operation S 504 , the scan result of the copy is stored in the memory  210 .  
       FIG. 6  shows the image compensating operation S 401  of  FIG. 4 .  
      Referring to  FIGS. 2 and 6 , the image compensating operation S 401  comprises a width comparing operation S 600 , RPM compensating operations S 601  and S 602 , a length comparing operations S 603 , RPM compensating operations S 604  and S 605 , and an RPM updating operation S 606 .  
      In the width comparing operation S 600 , sizes of the reference document and the copy are extracted from the stored scan information, and the width of the reference document is compared with the width of the copy.  
      In the RPM compensating operations S 601  and S 602 , RPMs P_MCLK and M_MCLK of the polygon and main motors are compensated according to the comparison results between the widths of the reference document and the copy. That is, when the widths of the reference document and the copy are identical to each other (R 1 =R 3 ), since there is no need of varying the RPM P_MCLK of the polygon motor, the RPM P_MCLK is not compensated and updated. Therefore, by comparing the lengths of the reference document and the copy, the RPM M_MCLK of the main motor is controlled.  
      In the length comparing operation S 603 , the lengths of the reference document and the copy are compared with each other using the stored scan information.  
      In the RPM compensating operations S 604  and S 605 , RPMs M_MCLK and P_MCLK of the main and polygon motors are controlled according to the comparison results of the RPM compensating operation S 603 .  
      In the RPM updating operation S 606 , the compensated RPMs of the main and polygon motors are updated and stored in the memory  210 .  
      There may be nine cases according to the widths and lengths of the documents.  
      (1) When R 1  is identical to R 3  (R 1 =R 3 ), there are following three cases.  
      (1a) When R 2  is identical to R 4  (R 2 =R 4 ), since the sizes of the reference document and the copy are identical to each other, the RPMs of the main and polygon motors are not compensated.  
      (1b) When R 2  is greater than R 4  (R 2 &gt;R 4 ), the RPMs of the motors are compensated. That is, since the length R 4  of the copy is less than the length R 2  of the reference document, the RPM M_MCLK of the main motor is increased by, for example, K 2 (R 2 −R 4 ), where the K 2  is a proportion constant that can be obtained by trial and error and experiments.  
      (1c)) When R 2  is less than R 4  (R 2 &lt;R 4 ), the RPMs of the motors are compensated. That is, since an image is increased in a lengthwise direction of the document, the RPM M_MCLK of the main motor is reduced by, for example, K 2 (R 2 −R 4 ), to compensate for the increased image in the lengthwise direction.  
      (2) When R 1  is greater than R 3  (R 1 &gt;R 3 ), there are following three cases.  
      (2a) When R 2  is identical to R 4  (R 2 =R 4 ), since the width of the copy is less than that of the reference document while the lengths of the reference document and the copy are identical to each other, the RPM P_MCLK of the polygon motor must be increased. At this point, the width of the print image may become reduced as the RPM P_MCLK of the polygon motor is increased. Therefore, the RPM M-MCLK of the main motor may need to be increased.  
      At this point, when the widths of the reference document and the copy are identical to each other (R 1 =R 3 ), it may be possible to independently adjust the length of the print image by compensating for only the RPM M_MLCK of the main motor without varying the RPM P_MLCK of the polygon motor. However, when the lengths of the reference document and the copy are identical to each other and the widths of the reference document and the copy are different from each other, it may be impossible to independently adjust the width of the print image by compensating only the RPM P_MLCK of the polygon motor. This is caused by an interrelation between the main motor controlling an advancing speed of the print document and the length of the print image, the poly motor controlling the width of the print image, and the video data inputted into the printer engine.  
      Therefore, considering the interrelation, after the RPM P_MCLK of the polygon motor, which is compensated with respect to a width difference, is first calculated, the RPM M_MCLK of the main motor must be compensated with respect to a length difference with reference to the calculated RPM of the polygon motor.  
      (2b) When R 2  is greater than R 4  (R 2 &gt;R 4 ), since the width and length of the copy are less than those of the reference document, the RPM P_MCLK of the polygon motor must be increased to increase the length of the print image. At this point, the length of the print image may become reduced as the RPM P_MCLK of the polygon motor is increased. Therefore, the RPM M-MCLK of the main motor needs to be increased at a predetermined rate according to a sum of a compensation of the reduced image length and a difference of the lengths of the reference document and the copy.  
      That is, the RPM P_MCLK of the polygon motor is increased according to K 1  (R 1 −R 3 ) and the RPM M_MCLK of the main motor is increased according to K 1  (R 1 −R 3 )+K 2 (R 2 −R 4 ) where K 1  and K 2  are a proportion constant that can be obtained by trial and error and experiments.  
      (2c) When R 2  is less than R 4  (R 2 &lt;R 4 ), since the width of the copy is less than that of the reference document while the length of the copy is greater than that of the reference document, the RPM P_MCLK of the polygon motor is increased. At this point, the length of the print image may be increased. Accordingly, the RPM M-MCLK of the main motor may need to be increased or reduced according to the increased length of the print image.  
      That is, the RPM P_MCLK of the polygon motor is increased by K 1  (R 10 −R 3 ) and the RPM M_MCLK of the main motor is increased or reduced by K 1  (R 1 −R 3 )+K 2 (R 2 −R 4 ).  
      (3) When R 1  is less than R 3  (R 1 &lt;R 3 ), there are following three cases.  
      (3a) When R 2  is identical to R 4  (R 2 =R 4 ), since the width of the copy is greater than that of the reference document while the lengths of the reference document and the copy are identical to each other, the RPM P_MCLK of the polygon motor must be reduced. At this point, since the width of the print image may be increased, the RPM M-MCLK of the main motor may need to be reduced according to the increased width of the print image.  
      That is, the RPM P_MCLK of the polygon motor is reduced by K 1  (R 1 −R 3 ) and the RPM M_MCLK of the main motor is reduced by K 1  (R 1 −R 3 )+K 2 (R 2 −R 4 ).  
      (3b) When R 2  is less than R 4  (R 2 &lt;R 4 ), since the width of the copy is greater than that of the reference document while the length of the copy is less than that of the reference document, the RPM P_MCLK of the polygon motor is reduced. At this point, since the length of the print image is increased, the RPM M-MCLK of the main motor must be increased or reduced considering the compensation of the RPM M_MCLK of the main motor.  
      That is, the RPM P_MCLK of the polygon motor is reduced by K 1  (R 1 −R 3 ) and the RPM M_MCLK of the main motor is increased or reduced by K 1  (R 1 −R 3 )+K 2 (R 2 −R 4 ).  
      (3c) When R 2  is less than R 4  (R 2 &lt;R 4 ), since the width and length of the copy is greater than those of the reference document, the RPM P_MCLK of the polygon motor is reduced. At this point, since the length of the print image is increased, the RPM M-MCLK of the main motor must be reduced considering the increased width and the difference between the R 2  and R 4 .  
      That is, the RPM P_MCLK of the polygon motor is increased by K 1  (R 1 −R 3 ) and the RPM M_MCLK of the main motor is reduced by K 1  (R 1 −R 3 )+K 2 (R 2 −R 4 ).  
      Table 1 shows the above-described nine cases to control the main and polygon motors.  
      In Table 1, K 2  indicates a proportion constant of the main motor controlling the lengths of the documents and K 1  indicates a proportion constant of the polygon motor controlling the widths of the documents.  
                           TABLE 1                           R1 = R3   R1 &gt; R3   R1 &lt; R3                  R2 = R4   Size of reference   RPM of polygon motor is   RPM of polygon motor is           document is   increased by K1(R1 − R3).   reduced by K1(R1 − R3).           identical to that of   RPM of main motor is   RPM of main motor is           copy   increased by K1(R1 − R3)   reduced by K1(R1 − R3)       R2 &gt; R4   RPM of main motor   RPM of polygon motor is   RPM of polygon motor is           is increased by   increased by K1(R1 − R3).   reduced by K1(R1 − R3).           K2(R2 − R4)   RPM of main motor is   RPM of main motor is               increased by K1(R1 − R3) + K2   increased or reduced by               (R2 − R4)   K1(R1 − R3) + K2(R2 − R4)       R2 &lt; R4   RPM of main motor   RPM of polygon motor is   RPM of polygon motor is           is reduced by   reduced by K1(R1 − R3).   reduced by K1(R1 − R3).           K2(R2 − R4)   RPM of main motor is   RPM of main motor is               reduced or increased by   reduced by K1(R1 − R3) +               K1(R1 − R3) + K2(R2 − R4)   K2(R2 − R4)                  
 
       FIG. 7  shows a flowchart illustrating the identifying operation S 402  of  FIG. 4 .  
      Referring to  FIG. 7 , the identifying operation S 402  comprises a reference document scan/output operation S 700 , a copy scan/output operation S 710 , a size comparison operation S 720 , and an image size compensation operation S 730 .  
      In the reference document scan/output operation S 700 , the reference document is scanned and outputted.  
      In the copy scan/output operation S 710 , the copy of the reference document is scanned and outputted.  
      In the size comparison operation S 720 , the sizes of the documents are extracted from the scan information of the reference document and the scan information of the copy, and the sizes are compared with each other to determine if the sizes are identical to each other.  
      In the image size compensation operation S 730 , when the sizes are not identical to each other, process is returned to operation S 401  to compensate the RPMs of the main and polygon motors and thereby to compensate the image size.  
       FIG. 8  shows a position of a reference document  810  loaded in a multifunction printer  8  according to another embodiment of the present general inventive concept.  
      Referring to  FIG. 8 , the reference document  810  is attached on a top of the multifunction printer  800  and is loaded in the multi printer by a button  820  provided on a side of the multifunction printer.  
      Although a few embodiments of the present general inventive concept have been shown and described, it will 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 general inventive concept, the scope of which is defined in the appended claims and their equivalents.