Patent Publication Number: US-2015077461-A1

Title: Printing compensation method for printing module

Description:
FIELD OF THE INVENTION 
     The present invention relates to a printing compensation method, and more particularly to a printing compensation method for a printing module of an inkjet printing system. 
     BACKGROUND OF THE INVENTION 
     As known, an inkjet printing system is easy to operate and is able to print on many kinds of media. Consequently, the inkjet printing system is gradually popular to many people and widely used by many users. 
     Generally, an inkjet printing system comprises several hundreds or even several thousands of nozzles. The diameters of these nozzles are in micrometer scales. However, after the inkjet printing system has been used for a certain time period, some of the nozzles are possibly clogged or damaged. 
     Conventionally, some methods for judging whether the nozzles are clogged or damaged were disclosed. For example, after an under-tested print document is compared with a standard print document, the user may visually judge whether the under-tested print document has any failed-printed part. As known, the visual comparison is neither objective nor accurate. Moreover, if the user confirms that some nozzles are clogged or damaged, the user usually replaces the inkjet printing module with a new one. The way of replacing the inkjet printing module is neither user-friendly nor cost-effective. Alternatively, the inkjet printing system is equipped with an additional inkjet printing module. The additional inkjet printing module may increase the cost of the inkjet printing system. 
     Therefore, there is a need of providing a printing compensation method for an inkjet printing system in order to overcome the above drawbacks. 
     SUMMARY OF THE INVENTION 
     The present invention provides a printing compensation method for an inkjet printing system. If any failed-print part is detected, a dynamic compensation module is enabled to perform a compensation printing operation. Consequently, the quality of the print result is enhanced. Since it is not necessary to replace the inkjet printing module or install an additional inkjet printing module when one or more nozzles are clogged or damaged, the inkjet printing system is more user-friendly and the operating cost is reduced. 
     In accordance with an aspect of the present invention, there is provided a printing compensation method for an inkjet printing system. The inkjet printing system includes a printing module, an image capture module and a dynamic compensation module. The printing module includes plural nozzles. The printing compensation method includes the following steps. First, a nozzle test pattern corresponding to the plural nozzles is printed out by the printing module. Then, a digital data corresponding to the nozzle test pattern is acquired by the image capture module, and a judging step is performed to judge whether any of the plural nozzles is abnormal according to the digital data. If at least one of the plural nozzles is abnormal, an information about at least one failed-print part corresponding to the at least one nozzle is acquired. Then, the dynamic compensation module is enabled to perform a compensation printing operation according to the information about the at least one failed-print part. 
     The above contents of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically illustrates the architecture of an inkjet printing system according to an embodiment of the present invention; 
         FIG. 2A  schematically illustrates a nozzle test pattern printed out by the printing module of the inkjet printing system of the present invention, in which the nozzle test pattern has no failed-print part; 
         FIG. 2B  schematically illustrates a nozzle test pattern printed out by the printing module of the inkjet printing system of the present invention, in which the nozzle test pattern has failed-print parts; 
         FIG. 3A  is a flowchart illustrating a printing compensation method according to an embodiment of the present invention; 
         FIG. 3B  is a flowchart illustrating a printing compensation method according to another embodiment of the present invention, in which the image capture module is a scanning module; and 
         FIG. 3C  is a flowchart illustrating a printing compensation method according to another embodiment of the present invention, in which the image capture module is an optical detecting module. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only. It is not intended to be exhaustive or to be limited to the precise form disclosed. 
       FIG. 1  schematically illustrates the architecture of an inkjet printing system according to an embodiment of the present invention. As shown in  FIG. 1 , the inkjet printing system  1  comprises a printing module  11 , an image capture module  12 , and a dynamic compensation module  13 . In an embodiment, the printing module  11  is a page-width printing module. The printing module  11  comprises one or more inkjet printing units  111  (see  FIGS. 2A and 2B ). The inkjet printing unit  111  comprises plural nozzles  1111 . The printing module  11  is fixed on a printing platform  14  of the inkjet printing system  1 . The printing module  11  is immobile, but a print medium (e.g. a paper) to be printed by the printing module  11  is moved relative to the printing module  11 . For testing whether the nozzles of the printing module  11  are normal or not, a nozzle test pattern  2  corresponding to odd-row nozzles  1111   a  and the even-row nozzles  1111   b  of the printing module  11  is firstly printed out by the printing module  11 . 
     As shown in  FIG. 2B , the dynamic compensation module  13  comprise one or more inkjet printing units  131 . Each inkjet printing units  131  is movable back and forth along a fixing mechanism  15 . That is, the dynamic compensation module  13  is movable relative to the printing platform  14  in a reciprocating manner. In this embodiment, the moving direction of the inkjet printing unit  131  of the dynamic compensation module  13  is perpendicular to the moving direction of the print medium. 
     For clarification and brevity, one inkjet printing unit  131  of the dynamic compensation module  13  and one inkjet printing unit  111  of the printing module  11  will be described as follows. 
     As shown in  FIG. 2A , the print result O1 corresponding to the odd-row nozzles and the print result E1 corresponding to the even-row nozzles are successfully and continuously printed out because all nozzles  1111  of the inkjet printing unit  111  are normal. 
     As shown in  FIG. 2B , the print result O2 corresponding to the odd-row nozzles and the print result E2 corresponding to the even-row nozzles are not successfully and continuously printed out because some nozzles are clogged or damaged. For example, the print result O2 of the nozzle test pattern  2  has a failed-print part corresponding to the seventh nozzle  1111   a   7  of the nozzles  1111   a  of the inkjet printing unit  111 ; and the print result E2 of the nozzle test pattern  2  has a failed-print part corresponding to the second nozzle  1111   b   2  of the even-row nozzles  1111   b  of the inkjet printing unit  111 . In other words, the seventh nozzle  1111   a   7  of the nozzles  1111   a  and the second nozzle  1111   b   2  of the even-row nozzles  1111   b  are clogged or damaged. 
     Please refer to  FIGS. 1 ,  2 A and  2 B again. Then, a digital data corresponding to the nozzle test pattern  2  is acquired by the image capture module  12 . An example of the image capture module  12  includes but is not limited to a scanning module or an optical detecting module. After the nozzle test pattern  2  is scanned by the scanning module, a digital data is acquired. According to the digital data, the inkjet printing system  1  may realize whether there is any failed-print part and obtain the information about the failed-print part. Then, the inkjet printing unit  131  of the dynamic compensation module  13  is enabled to perform a compensation printing operation according to the information about the failed-print part. The optical detecting module may detect the print data of the nozzle test pattern  2  corresponding to the plural nozzles  1111  and judge whether the intensities of the reflected light beams are normal or not. If any failed-print part is detected, the information about the failed-print part is acquired. Similarly, the inkjet printing unit  131  of the dynamic compensation module  13  is enabled to perform a compensation printing operation according to the information about the failed-print part. 
       FIG. 3A  is a flowchart illustrating printing a compensation method according to an embodiment of the present invention. 
     Firstly, a nozzle test pattern  2  corresponding to odd-row nozzles  1111   a  and the even-row nozzles  1111   b  of the printing module  11  is printed out by the printing module  11  (Step S 31 ). Then, a digital data corresponding to the nozzle test pattern  2  is acquired by the image capture module  12  (Step S 32 ). Then, the step S 33  is performed to judge whether any of the plural nozzles  1111  is abnormal according to the digital data. 
     If the judging condition of the step S 33  is not satisfied, it means that the plural nozzles  1111  of the printing module  11  are not clogged or damaged (see  FIG. 2A ). Under this circumstance, it is not necessary to perform the compensation printing operation. On the other hand, if the judging condition of the step S 33  is satisfied, it means that one or more of the plural nozzles  1111  of the printing module  11  are clogged or damaged (see  FIG. 2B ). Then, the number of the at least one failed-print part and the information about the at least one failed-print part are acquired (Step S 34 ). Then, the dynamic compensation module  13  is enabled to perform a compensation printing operation according to the information about the failed-print part (Step S 35 ). For example, after the compensation printing operation is performed on the print result of  FIG. 2B , the print result as shown in  FIG. 2A  is produced. 
     In this embodiment, if the compensation printing operation has to be performed, a notification signal is issued to notify the user that the inkjet printing unit  131  of the dynamic compensation module  13  needs to be installed or the inkjet head of the inkjet printing unit needs to be replaced. For example, the notification signal is a flashing light, or the notification signal is a notification message shown on a computer monitor. After the inkjet printing unit  131  of the dynamic compensation module  13  is installed, the dynamic compensation module  13  is moved to desired locations to perform the compensation printing operation. For example, after the dynamic compensation module  13  is moved relative to the printing platform  14  in a reciprocating manner, the print data of the failed-print parts as shown in  FIG. 2B  are compensated. Consequently, the entire of the print data as shown in  FIG. 2A  will be printed out by the inkjet printing system  1 . 
       FIG. 3B  is a flowchart illustrating a printing compensation method according to another embodiment of the present invention, in which the image capture module is a scanning module. In this embodiment, the image capture module  12  is a scanning module. After the nozzle test pattern  2  is generated by the scanning module (Step S 31 ), the nozzle test pattern  2  is scanned by the scanning module, so that a digital data corresponding to the nozzle test pattern  2  is acquired (Step S 321 ). Then, the step S 33  is performed to judge whether any of the plural nozzles  1111  is abnormal according to the digital data. If the judging condition of the step S 33  is satisfied, the number of the at least one failed-print part and the information about the at least one failed-print part are acquired (Step S 34 ). Then, the dynamic compensation module  13  is enabled to perform a compensation printing operation according to the information about the failed-print part (Step S 35 ). 
       FIG. 3C  is a flowchart illustrating a printing compensation method according to another embodiment of the present invention, in which the image capture module is an optical detecting module. In this embodiment, the image capture module  12  is an optical detecting module. After the nozzle test pattern  2  is generated by the scanning module (Step S 31 ), the optical detecting module is moved from left to right in order to detect the intensities of the reflected light beams from the print data of the nozzle test pattern  2  corresponding to the odd-row nozzles  1111   a  (Step S 3221 ). As shown in  FIG. 2B , the intensities of the reflected light beams from the print result O2 are detected. Then, the optical detecting module is moved from right to left in order to detect the intensities of the reflected light beams from the print data of the nozzle test pattern  2  corresponding to the even-row nozzles  1111   b  (Step S 3222 ). As shown in  FIG. 2B , the intensities of the reflected light beams from the print result O2 are detected. Then, a digital data corresponding to the nozzle test pattern  2  is acquired by the optical detecting module according to the intensities of the reflected light beams (Step S 3223 ). Then, the step S 33  is performed to judge whether any of the plural nozzles  1111  is abnormal according to the digital data. If the judging condition of the step S 33  is satisfied, the number of the at least one failed-print part and the information about the at least one failed-print part are acquired (Step S 34 ). Then, the dynamic compensation module  13  is enabled to perform a compensation printing operation according to the information about the failed-print part (Step S 35 ). 
     From the above descriptions, the present invention provides a printing compensation method for an inkjet printing system. The inkjet printing system comprises a printing module, an image capture module, and a dynamic compensation module. Firstly, a nozzle test pattern is printed out by the printing module. Then, a digital data corresponding to the nozzle test pattern is acquired by the image capture module. If any failed-print part is detected, the information about the failed-print part is acquired. Moreover, the inkjet printing unit of the dynamic compensation module is enabled to perform a compensation printing operation according to the information about the failed-print part. Consequently, the quality of the print result is enhanced. Since it is not necessary to replace the inkjet printing module or install an additional inkjet printing module when one or more nozzles are clogged or damaged, the inkjet printing system is more user-friendly and the operating cost is reduced. Moreover, according to the digital data, the inkjet printing system may realize whether there is any failed-print part and obtain the information about the failed-print part. Consequently, the statuses of the nozzles of the printing module can be realized more objectively and accurately. 
     While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.