Abstract:
When printing on the same printing object with multiple print nozzles in the past, consideration was not given to cases in which the time relationships of the set times and times-to-be-printed become mismatched between the respective print items of the print nozzles. To solve said problem, the present invention is an inkjet printer for printing on a conveyed printing object and having multiple print nozzles, multiple auxiliary control units for controlling the printing performed by the multiple print nozzles, and a common main control unit connected to the multiple auxiliary control units via communication means. The main control unit is configured to be equipped with: an extracting function for extracting the time relationship of the set times and the time relationship of the times-to-be-printed between the items to be printed by the respective print nozzles of the multiple print nozzles; and a revising function for revising the print data so as to preserve the time relationship of the set times.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an inkjet printer. 
       BACKGROUND ART 
       [0002]    An inkjet printer (hereinafter referred to as IJP) is widely used for applications such as printing characters to represent a production lot number, a production date, an expiration date, etc. upon a product. Especially, in the food industry or the like, a production time is often printed together with an expiration date and, lately, a requirement has been made to print a time in hours, minutes, and even seconds. 
         [0003]    To fulfill the above requirement, an IJP acquires time information from a Real Timer Clock (hereinafter referred to as RTC) and, using the time information, displays a time on screen and automatically updates and creates print data representing current time information and prints a time (hereinafter referred to as calendar printing). However, when calendar printing is performed with a plurality of IJPs, because the RTC of each IJP operates asynchronously, synchronizing times must be performed manually for calendar printing of a same time with the IJPs, each time a difference between times occurs, and this requires a lot of labor. 
         [0004]    As a background art in the present technical field, there is Japanese Unexamined Patent Application Publication No. 2003-182060 (Patent Literature 1). Patent Literature 1 describes an inkjet printing system which includes a plurality of IJPs that print time information on one printing object and which is arranged such that updating time information to be printed by the plurality of IJPs is managed by a common main controlling device to avoid inconsistency of times to be printed by each IJP. 
       CITATION LIST 
     Patent Literature 
       [0005]    Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2003-182060 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0006]    However, in Patent Literature 1, no consideration was taken for a case where a time relationship between print items becomes inconsistent between a time that is set and a time that is printed. For instance, it is assumed that, when an IJP (A) prints an expiration date and an IJP (B) prints a production time on the same printing object, one day after the current date is set to be printed as the expiration date and the current time (in hours, minutes, and even in seconds) is set to be printed as the production time. This case is explained below. For instance, when a printing object detection signal detecting the arrival of a printing object becomes ON at 23 o&#39;clock, 59 minutes, and 59 seconds on Mar. 30, 2014, the IJP (A) acquires and creates current date time data (Mar. 30, 2014) and prints an expiration date of 14.3.31 which is one day after the current date on the printing object, whereas the IJP (B) may print a production time of 00:00:00 of day 31 on the printing object. This is because time after the printing object detection signal until printing starts by printing setting (this time is referred to as printing start preparation time, hereinafter) differs with respect to each IJP. In this case, although the respective IJPs printed times as set, printing results show that the same day is printed as the expiration date and the production date on the same printing object and inconsistency between what has been set and what is printed occurs. 
         [0007]    Therefore, the present invention provides an inkjet printer that performs a printing operation to avoid inconsistency between what has been set and what is printed between print items (such operation is referred to as synchronizing times, hereinafter) when printing on the same printing object with a plurality of nozzles. Further, the present invention provides an inkjet printer in which this inkjet printer can set items to synchronize times to print easily. 
       Solution to Problem 
       [0008]    To solve the problem noted above, for example, a configuration as described in claims is adopted. By way of example, an inkjet printer that prints on a printing object being conveyed is configured as follows: the inkjet printer includes a plurality of printing nozzles, a plurality of auxiliary control units that control printing with the plurality of printing nozzles, and a common main control unit connected to the plurality of auxiliary control units through communication means; and the main control unit is provided with a deriving function to derive a relationship between times that have been set and a relationship between times that are printed between print items with each of the plurality of printing nozzles and a correcting function to correct print data to maintain the relationship between times that have been set. 
       Advantageous Effects of Invention 
       [0009]    According to the present invention, it is enabled to perform printing, while maintaining a time synchronization relationship between items to synchronize, which have been set. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]      FIG. 1  is a block diagram depicting a configuration of an inkjet printer according to an embodiment of the present invention. 
           [0011]      FIG. 2  are setting screens of a touch input &amp; display panel of the inkjet printer according to the present embodiment. 
           [0012]      FIG. 3  is a setting screen for editing what is printed for each item number on the touch input &amp; display panel of the inkjet printer according to the present embodiment. 
           [0013]      FIG. 4  is a flowchart of a process for synchronizing times, which is executed by a main control unit of the inkjet printer according to the present embodiment. 
           [0014]      FIG. 5  is a time flow diagram illustrating a time printing operation of the inkjet printer according to the present embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0015]    In the following, an embodiment of the present invention will be described with the drawings. 
         [0016]      FIG. 1  is a block diagram depicting a configuration of an inkjet printer according to the present embodiment. Reference numeral  100  denotes a main control unit that exerts overall control of the inkjet printer;  200  and  300  denote auxiliary control units that control respective nozzles; and  400  denotes a print head portion. 
         [0017]    The main control unit  100  includes a main MPU (micro processing unit)  101  that exerts overall control of the inkjet printer, a RAM (random access memory)  102  that temporarily stores data in the inkjet printer, a ROM (read only memory)  103  that stores software and data, a time update control unit  104 , a dual port communication interface circuit  105 , a printing object detecting circuit  106 , a touch input &amp; display panel  107 , an RTC  108  having time information, and a bus  109  for communication of data or the like. 
         [0018]    An auxiliary control unit  200  includes an auxiliary MPU (micro processing unit)  201  that controls printing with a nozzle, a RAM (random access memory)  202  that temporarily stores data, a ROM (read only memory)  203  that stores data, a printing voltage generating circuit  204 , a dual port communication interface circuit  205 , a printing object detecting and inputting circuit  206 , a printing control circuit  207 , and a bus  208  for communication of data or the like. 
         [0019]    An auxiliary control unit  300 , like the auxiliary control unit  200 , includes an auxiliary MPU (micro processing unit)  201  that controls printing with a nozzle, a RAM (random access memory)  302  that temporarily stores data, a ROM (read only memory)  203  that stores data, a printing voltage generating circuit  304 , a dual port communication interface circuit  305 , a printing object detecting and inputting circuit  206 , a printing control circuit  307 , and a bus  308  for communication of data or the like. 
         [0020]    The print head portion  400  includes a nozzle A  401  and a nozzle B  411  that jet ink, charging electrodes  402  and  412  that charge printing particles, deflecting electrodes  403  and  413  that deflect ink particles, gutters  404  and  414  for collecting ink particles not used for printing, and pumps  405  and  415  that collect ink. 
         [0021]    In addition, the dual port communication interface circuit  105  of the main control unit  100 , the dual port communication interface circuit  205  of the auxiliary control unit  200 , and the dual port communication interface circuit  305  of the control circuit  300  are connected through a signal line  111 . The printing object detecting circuit  106  of the main control unit  100 , the printing object detecting and inputting circuit  206  of the auxiliary control unit  200 , and the printing object detecting and inputting circuit  306  of the auxiliary control unit  300  are connected through a signal line  110 . That is, the main control unit  100  and the auxiliary control units  200 ,  300  are connected by the dual port communication interface circuits which are communication means and the signal lines. 
         [0022]    By operating the touch input &amp; display panel  107  and inputting initial settings and printing information, this inkjet printer, particularly, the main MPU  101  of the main control unit  100  and the auxiliary MPUs  201 ,  301  of the auxiliary control units  200 ,  300  executes a printing control process, as will be described below, according to a printing control program stored in the ROMs  103 ,  203 ,  303 . 
         [0023]    The main MPU  101  of the main control unit  100  prompts an operator to input initial settings and printing information via the touch input &amp; display panel  107  and the thus input initial settings and printing information are transferred through the bus line  109  and stored into the RAM  102 . 
         [0024]      FIG. 2  depict function setting screens which are displayed on the touch input &amp; display panel  107 . 
         [0025]      FIG. 2(A)  is a screen displaying what is printed, in which machine information is displayed, including the current time, what is printed, machine time, operating time, the number of printings done, ink pressure, etc. In the box “what is printed”, item 1 represents an expiration period, item 2 represents a production date (year/month/day and in hours/minutes, a production line number), item 3 represents a lot number. 
         [0026]    Further,  FIG. 2(B)  is a screen for setting time synchronization, in which “synchronize times” sets whether the auxiliary control units  200 ,  300  need to exert control to synchronize times to print (“Do” requests the auxiliary control units to exert control to synchronize times). The “number of items to synchronize” sets the number of items for which the auxiliary control units  200 ,  300  need to synchronize times.  FIG. 2(B)  illustrates an example in which the auxiliary control units are requested to exert control to synchronize times of two items: item 1, expiration date and item 2, production date. At the bottom of the screen, the touch panel&#39;s keyboard for input is shown. 
         [0027]    Further,  FIG. 3  depicts a setting screen example for editing what is printed for each item number on the touch input &amp; display panel. In  FIG. 3 , an upper half part of the screen is a screen displaying items in the current status and three items are displayed in the current status. When editing what is printed, by choosing any item, the item number is displayed, and the background color of the chosen item turns gray. By pressing “Fix” during editing, a value entered is fixed and reflected in a print. There is an area for editing what is printed in the center of the screen and arrows at both sides of the area are used to scroll within the area for editing what is printed. The area for editing what is printed is also provided with a scale (1 10 20) indicating the number of characters that are present in the area for editing what is printed. In a lower part of the screen, a keyboard for input is shown. 
         [0028]    The main MPU  101  of the main control unit  100  transmits initial settings and printing information which have been input to the auxiliary MPUs  201 ,  301  of the auxiliary control units  200 ,  300  through the dual port communication interface circuit  105 , signal line  111 , and dual port communication interface circuits  205 ,  305 . 
         [0029]    The auxiliary MPUs  201 ,  301  of the auxiliary control units  200 ,  300  transfer the received initial settings and printing information through the bus lines  208 ,  308  and store them into the RAMs  202 ,  302 . After that, the auxiliary MPUs  201 ,  301  creates or updates print data, based on the printing information, and further converts the print data to charging data like staircase waves and stores that data into the RAMs  202 ,  302 . Upon detecting arrival of a printing object  501  with a printing object detecting sensor, the printing object detecting circuit  106  generates a printing object detection signal and this printing object detection signal is transferred to the main MPU  101  though the bus line  109 . Also, the printing object detecting circuit  106  transmits a printing start command signal to the auxiliary MPUs  201 ,  301  through the signal line  111  and via the printing control circuits  207 ,  307 . 
         [0030]    When the auxiliary MPUs  201 ,  301  receive the printing start command signal, the auxiliary MPUs retrieve the charging data like staircase waves from the RAMs  202 ,  302  and transmit that data to the printing voltage generating circuits  204 ,  304  through the bus lines  208 ,  308 . The printing voltage generating circuits  204 ,  304  convert the charging data like staircase waves transmitted to them to a charging voltage and send the charging voltage to the charging electrodes  402  and  412  which, in turn, charge ink particles to carry out printing. 
         [0031]    When the printing voltage generating circuits  204 ,  304  completes converting all the charging data like staircase waves transmitted to them, printing is then complete. The printing voltage generating circuits  204 ,  304  notifies the auxiliary MPUs  201 ,  301  that printing is complete through the bus lines  208 ,  308 . 
         [0032]    When the auxiliary MPUs  201 ,  301  receive this printing complete notification, the auxiliary MPUs notify the main MPU  101  that printing is complete through the bus lines  208 ,  308 , dual port communication interface circuits  205 ,  305 , signal line  111 , dual port communication interface circuit  105 , and bus line  109 . 
         [0033]    Then, a description is provided about a series of operations to synchronize print data based on a relationship between times to synchronize, when time information is included in print data.  FIG. 4  is a flowchart of a process for synchronizing times, which is executed by the main MPU  101 . Further,  FIG. 5  is a time flow diagram illustrating a time printing operation.  FIG. 5  illustrates an example in which an auxiliary control unit (1) (the auxiliary control unit  200 ) prints item 1, expiration date and an auxiliary control unit (2) (the auxiliary control unit  300 ) prints item 2, production date on the same printing object. 
         [0034]    First, at step S 1  in  FIG. 4 , through the bus line  109 , the main MPU  101  acquires from the RAM  102  what has been set for items to synchronize, i.e., a setting to synchronize times is “Do”, the number of items to synchronize is “2”, and the item numbers to synchronize are “1” and “2”. Through the bus line  109 , the main MPU  101  also acquires time data from the RAM  102  and divides that data into the following levels: year/month/day and in hours/minutes/seconds. 
         [0035]    In the present embodiment, time data for item 1, expiration date has been set as year/month/day; therefore, such time data, year/month/day is stored into the RAM  102 . That is, in  FIG. 5 , the auxiliary control unit (1) acquires a time to print at timing (a) and a value of date (2014.04.01) in the corresponding field, which is an expiration date that is obtained by adding two days to the current date (2014. 03.30), is stored as follows: 
         [0000]    RAM_Year_1=2014
 
RAM_Month_1=04
 
RAM_Day_1=01
 
         [0036]    Likewise, time data for item 2, production date has been set as year/month/day and in hours/minutes; therefore, such time data even in minutes is stored into the RAM  102 . That is, in  FIG. 5 , the auxiliary control unit (2) acquires a time to print at timing (a) and a value of the current time (2014.03.30 23:59) in the corresponding field, which is the time of production, is stored as follows: 
         [0000]    RAM_Year_2=2014
 
RAM_Month_2=03
 
RAM_Day_2=30
 
RAM_Hour_2=23
 
RAM_Minute_2=59
 
         [0037]    Next, at step S 2 , a relationship between the times for the items to synchronize times is derived by a calculation method as below and stored as RAM_Difference1. Here, the relationship between the times literally indicates a relationship between both. In the present embodiment, as the items to synchronize times, item 1 is expiration date and item 2 is production date, and the expiration date is set to a day that is obtained by adding two days to the production date; therefore, two days are obtained as the relationship between the times that have been set for the two items to synchronize. In other words, it can also be said that a difference value between the items to synchronize times is obtained. And now, because item 1, expiration date is set as year/month/day and item 2, production date is set even in minutes, the relationship between the times for the two items to synchronize is derived in terms of year/month/day. 
         [0000]      RAM_Year_difference=RAM_Year_1−RAM_Year_2=2014−2014=0
 
         [0000]      RAM_Month_difference=RAM_Month_1−RAM_Month_2=04−03=1
 
         [0000]      RAM_Day_difference=RAM_Day_1−RAM_Day_2=01−30=−29
 
         [0000]      RAM_Day_1 (new)=RAM_Month_difference×31 days+RAM_Day_1=31+1=32
 
         [0000]      RAM_Day_difference (new)=RAM_Day_1 (new)−RAM_Day_2=32−30=2
 
         [0000]      RAM_Difference1=RAM_Day_difference (new)=2 
         [0038]    As described above, the process is arranged such that a relationship between times that have been set for items to synchronize is derived and stored when initial setting is performed; however, a relationship between times that have been set may be derived and stored retroactively when setting item numbers to synchronize in  FIG. 2 . 
         [0039]    Next, at step S 3 , the RTC  108  acquires time in units of seconds and transfers the time information to the main MPU  101  through the bus line  109 . The main MPU  101  stores the time information into the RAM  102  and updates the current time. 
         [0040]    At step S 4 , the main MPU  101  judges whether there is a printing object detection signal. If there is no printing object detection signal, the main MPU  101  returns to step S 3  and updates the current time. If there is a printing object detection signal, the main MPU  101  controls timing to start printing by printing setting at step S 5 . That is, through the bus line  109 , the main MPU acquires a time to print for print item 1 at timing (b) in  FIG. 5  from the RTC  108  and a value of date (2014.04.01) in the corresponding field when the auxiliary control unit (1) acquires a time to print, which is an expiration date that is obtained by adding two days to the current date, is stored as RAM_Year_1=2014, RAM_Month_1=04, RAM_Day_1=01. 
         [0041]    At step S 6 , the main MPU  101  creates print data from information corresponding to the print item 1 received from the RTC  108  and stores the print data into the RAM  102  through the bus line  109 . At step  7 , the main MPU  101  transmits the print data to the auxiliary MPU  200  through the bus line  109 , dual port communication interface circuit  105 , signal  101 , and dual port communication interface circuit  205 . 
         [0042]    At step S 8 , through the bus line  109 , the main MPU  101  acquires a time to print for print item 2 from the RTC  108  and a value of the current time (2014.03.31 00:00) as the time of production in the corresponding field, when the auxiliary control unit (2) acquires a time to print at timing (b) in  FIG. 5 , is stored into the RAM  102  as RAM_Year_2=2014, RAM_Month_2=03, RAM_Day_2=31, RAM_Hour_2=00, RAM_Minute_2=00. 
         [0043]    Next, at step S 9 , the main MPU  101  automatically drives a relationship between the times for the two items to synchronize in terms of year/month/day by a calculation method as below and stores it into the RAM  102  as RAM_Difference2. 
         [0000]      RAM_Year_difference=RAM_Year_1−RAM_Year_2=2014−2014=0
 
         [0000]      RAM_Month_difference=RAM_Month_1−RAM_Month_2=04−03=1
 
         [0000]      RAM_Day_difference=RAM_Day_1−RAM_Day_2=01−31=−29
 
         [0000]      RAM_Day_1 (new)=RAM_Month_difference×31 days+RAM_Day_1=31+1=32
 
         [0000]      RAM_Day_difference (new)=RAM_Day_1 (new)−RAM_Day_2=32−31=1
 
         [0000]      RAM_Difference2=RAM_Day_difference (new)=1 
         [0044]    At step S 10 , the main MPU  101  compares relationship 1 between the times (RAM_Difference1) with relationship 2 between the times (RAM_Difference2). If the relationships match, main MPU  101  creates print data for item 2 and stores that data into the RAM  102  at step S 11 . If the relationships do not match, the main MPU  101  retrieves previously stored print data for item 2 from the RAM  102  through the bus line  109  at step S 12 . 
         [0045]    In the case of the present embodiment, relationship 1 between the times (RAM_Difference1) is 2 and relationship 2 between the times (RAM_Difference2) is 1. That is, the expiration date is set to a day that is obtained by adding two days to the production date, whereas relationship 2 is “+1 day”. Therefore, the decision at step S 10  is mismatch. Then, at step S 12 , the main MPU  101  retrieves previously stored print data (2014.03.30 23:59) for item 2 from the RAM  102  through the bus line  109  (a value in the corresponding field, when the auxiliary control unit (2) creates print data at timing (b) in  FIG. 5 ). 
         [0046]    Then, at step S 13 , the main MPU  101  transmits the print data to the auxiliary MPU  300  through the bus line  109 , dual port communication interface circuit  105 , signal line  111 , and dual port communication interface circuit  305 . 
         [0047]    By executing the above-described process, it is possible to maintain the relationship that is +2 days between the expiration date and the production data at any timing when the auxiliary control unit (1) starts printing and the auxiliary control unit (2) starts printing, as illustrated in  FIG. 5 . It is thus possible to perform a printing operation to avoid inconsistency between what has been set and what is printed, when printing on the same printing object with a plurality of nozzles. 
         [0048]    Therefore, according to the present embodiment, it is enabled to perform printing, while maintaining a time synchronization relationship between items to synchronize, which have been set. 
         [0049]    While the embodiment has been described hereinbefore, the present invention is not limited to the foregoing embodiment and various modifications are included therein. For example, although the embodiment where printing is performed with two printing nozzles was described, printing may be performed with three or more nozzles. Further, the present invention is not necessarily limited to an embodiment including all components described. For a subset of the components of the embodiment, other components can be added to the subset or the subset can be removed or replaced by other components. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           100 : Main control unit 
           102 : RAM 
           106 : Printing object detecting circuit 
           107 : Touch input &amp; display panel 
           108 : RTC (Real Timer Clock) 
           200 ,  300 : Auxiliary control unit 
           400 ; Printing head