Abstract:
A device for and a method of transmitting serial data and/or addresses to a printer head. A data processing unit provides serial input data for determining nozzles to be fired simultaneously and data for controlling a nozzle group firing order. The serial data is converted to parallel data and bits for determining the simultaneous firing nozzles are separated from a bit which determines the nozzle group firing order. A bi-directional shift register has parallel outputs which are changed by shifting a preset value left or right based on a latch clock and the firing order bit. The converted parallel input data and the outputs of the bi-directional shift register are logic ANDed to output nozzle firing signals. Logic operations in the printer head are simplified, a number of connections is reduced, and interface signals between the printer head and the printer main body are minimized.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
         [0001]    This application claims the benefit of Korean Patent Application No. 2002-64589, filed Oct. 22, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to an inkjet printer, and more particularly, to a device for and method of transmitting serial data and/or addresses for a printer head and a printer.  
           [0004]    2. Description of the Related Art  
           [0005]    [0005]FIG. 1 is a view for showing a device for driving a conventional printer head, which is disclosed in U.S. Pat. No. 6,312,079.  
           [0006]    As shown in FIG. 1, the conventional printer has a group data line  4  for selecting a nozzle group, a primitive data line  20  for selecting nozzles to be fired at the same time, a clock  1  line  18  for shifting the group data and the primitive data in a shift latch, and an interface signal for a fire pulse  38 . Further, the conventional printer has first memories  6  for storing serial group selection data and second memories  22  for storing serial primitive data, and additionally has a decoder  30  for decoding the serial group data and AND gates  36  for carrying out AND-operations with first memory data  52  and second memory data  54 . Further, a clock  2  ( 44 ) is included to latch the outputs of the AND gates  36  to a fire pulse latch  32 .  
           [0007]    The output of the fire pulse latch  32  is logic-ANDed with the fire pulse  38  through an AND gate  40 , and the output of the AND gate  40  is applied to the gate of a driving FET(not shown) for each head nozzle. Such a conventional printer as structured above selects a nozzle group through the group data line  4 , and stores firing data in the first memories  6  and the second memories  22  through the primitive data line  20  in synchronization with the clock  1   18 . The serial nozzle group selection data stored in the first memories  6  selects one nozzle group through the decoder  30 . Further, the firing data stored in the second memories  22  is ANDed with the nozzle group selection data and then latched in synchronization with a signal of clock  2   44 . Such latched data is ANDed with the fire pulse  38  again, and transmitted to the gate of the driving FET for each nozzle. Accordingly, only the nozzles in nozzle groups selected from the nozzles of a printer head are fired.  
           [0008]    However, the conventional printer has the connections of the serial group data lines in addition to the serial primitive data lines so as to have plural interface signals. Accordingly, the conventional printer has the complicated connections between the printer head and the printer, which increases error factors during the manufacture of printer heads or during printing. Further, there exist as many fire pulse latches  32  latching firing data and AND gates  36  as the nozzles of the printer head, which causes a problem of increasing logic operations in the printer head.  
         SUMMARY OF THE INVENTION  
         [0009]    Accordingly, it is an aspect of the present invention to minimize interface signals between a printer head and a printer to simplify connection of the printer and the printer head.  
           [0010]    It is another aspect of the present invention to simplify logic operations in the printer head to minimize a printer head logic unit.  
           [0011]    According to an aspect of the present invention, a method of transmitting serial data/addresses for a printer head comprises generating and supplying data for determining simultaneous firing nozzles and a nozzle group firing direction through a fire/group direction data line; latching the data supplied through the fire/group direction data line to first memories in synchronization with a shift clock; storing data for determining the simultaneous firing nozzles in second memories in synchronization with the latched outputs of the first memories and a latch clock; outputting signals for selecting nozzle groups from a bi-directional shift register in synchronization with the latch clock provided from the latch clock line, ANDing the simultaneous firing nozzle data outputted from the second memories in synchronization with a fire pulse to generate the simultaneous firing data; and ANDing the stored data for determining simultaneous firing pulses and the nozzle group selection signals of the bi-directional shift register to apply driving signals to the gates of FETs driving nozzles so that selected nozzles are fired.  
           [0012]    According to an aspect of the present invention, a device for transmitting serial data/addresses for a printer head comprises a data processing unit which provides simultaneous firing nozzle data, data for determining a nozzle group firing direction, and a fire pulse; a firing group direction data linewhich provides the data for determining the simultaneous firing nozzles and the nozzle group firing direction to the printer head; a fire pulse line which provides the fire pulse to the printer head; a first selection unit which selects the simultaneous firing nozzles based on the fire/group firing direction data; a second unit which selects specific firing nozzles through the first selection unit based on the fire pulse; a bi-directional shift register which generates firing nozzle group selection signals; and a firing unit which fires the specific nozzles selected based on the firing nozzle group selection signals.  
           [0013]    The device may further comprise first memories which store the simultaneous firing nozzle data and the nozzle group firing direction data, wherein a number of the first memories is one more in number than a number of the simultaneous firing nozzles.  
           [0014]    The device may further comprise second memories which store the simultaneous firing nozzle data, wherein a number of the second memories equals the number of the simultaneous firing nozzles.  
           [0015]    The device may further comprise as many logic AND gates which logic-AND the simultaneous firing nozzle data and the fire pulse signal as the number of the simultaneous firing nozzles, and may further comprise as many logic AND gates which logic-AND the outputs of the first logic AND unit and the nozzle group selection signals of the bi-directional shift register as a number of the nozzles of the printer head.  
           [0016]    Additional aspects and/or 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  
       [0017]    The above and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the preferred embodiments taken in conjunction with the accompanying drawings in which: The invention will be described in detail with reference to the following drawings in which like reference numerals refer to like elements, and wherein:  
         [0018]    [0018]FIG. 1 is a view for schematically showing a conventional device for driving a printer head;  
         [0019]    [0019]FIG. 2A is a view for schematically showing a portion of an apparatus for serial data/address transmission device according to the present invention;  
         [0020]    [0020]FIG. 2B is a view for schematically showing another portion of the apparatus for serial data/address transmission according to the present invention;  
         [0021]    [0021]FIG. 3 is a table for illustrating logic operations of the portion of the apparatus shown in FIG. 2B; and  
         [0022]    [0022]FIG. 4 is a flow chart for explaining an operation of the apparatus shown in FIGS. 2A and 2B. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0023]    Reference will now be made in detail to the present preferred 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.  
         [0024]    [0024]FIGS. 2A and 2B are block diagrams for schematically showing a serial data/address transmission device for a printer head according to an embodiment of the present invention. As shown in FIGS. 2A and 2B, the serial data/address transmission device comprises a data processor  100 , a plurality of first memories  120 , a plurality of second memories  130 , a first logic AND unit  140 , a second logic AND unit  150 , and a bi-directional shift register  160 . The data processor  100  provides input data to the printer head. The input data provided comprises data for nozzles to be fired at the same time and data for determining a firing order of nozzle groups to be fired (nozzle group direction data) through a fire/group direction data line  110 . Further, a fire pulse to determine a final fire is provided to the printer head through the fire pulse line  113 . A shift clock to latch data is provided to the printer head through a shift clock line  111  in order to store the input data in the first memories  120 , and a latch clock for latching nozzle group data is provided to the printer head through the latch clock line  112 .  
         [0025]    The first memories  120  store the input data which are sequentially latched by the shift clock  111 . A number of the first memories  120  is one more than a number of the simultaneous firing nozzles (the invention is illustrated with an embodiment comprising four nozzles) in order to provide the direction data of a firing group to a port (dir) of the bi-directional shift register  160 .  
         [0026]    If the firing direction data and the firing nozzle data are all latched to the first memories  120 , the second memories  130  latch the firing nozzle data, synchronizing the outputs (Q) of the first memories  120  with the latch clock of the latch clock line  112 , and determine and output simultaneous firing nozzle signals, Q 1 , Q 2 , Q 3 , Q 4 . Further, a number of the second memories  130  is the same as the number of the simultaneous firing nozzles.  
         [0027]    The first logic AND unit  140  ANDs the firing nozzle signals Q 1 , Q 2 , Q 3 , Q 4  output from of the second memories  130  and the fire pulse to determine final firing signals S 1 , S 2 , S 3  and S 4  to fire the simultaneous firing nozzles. A number of individual AND gates ( 140 - 1 ,  140 - 2 ,  140 - 3 ,  140 - 4 ) required in the first logic AND unit  140  is the same as the number of the simultaneous firing nozzles.  
         [0028]    In the meantime, the bi-directional shift register  160  outputs signals except for the MSB and the LSB in order to choose nozzle groups (for example, four groups in the embodiment) from the outputs of the nozzle group selection signals QB, QC, QD and QE. The bi-directional shift register  160  is loaded with data having an MSB of “1” and an LSB of “1” and the loading is performed in every slice, and the data is shifted in synchronization with the latch clock of the latch clock line  112 . With the shift operations according to the latch clock of the latch clock line  112 , the nozzle group selection data is output to the second AND unit  150  with the generation of a signal selecting only one nozzle group from the nozzle groups QB - QE. The shift direction is determined with reference to the nozzle group direction data provided to the port “dir” out of the data latched through the fire/group direction data line  110 .  
         [0029]    The second AND unit  150  ANDs the firing nozzle group selection signals (QB, QC, QD, QE) output from the bi-directional shift register  160  and the outputs (S 1 , S 2 , S 3 , S 4 ) of the first logic AND unit  140 , and determine and outputs simultaneous firing nozzle signals for a selected nozzle group so that the selected nozzle signals are connected to respective gates of corresponding FETs be fired (B 1 -B 4 , C 1 -C 4 , D 1 -D 4 , E 1 -E 4 ).  
         [0030]    Referring now to FIG. 2B, the output S 1  of the first logic AND unit  140  is simultaneously connected to respective first inputs of AND gates  150 B 1 ,  150 C 1 ,  150 D 1 , and  150 E 1  of the second AND unit  150 . Similarly, the output S 2  of the first logic AND unit  140  is simultaneously connected to respective first inputs of AND gates  150 B 2 ,  150 C 2 ,  150 D 2  and  150 E 2  of the second AND unit  150 ; the output S 3  of the first logic AND unit  140  is simultaneously connected to respective first inputs of AND gates  150 B 3 ,  150 C 3 ,  150 E 3 ; and the output S 4  of the first logic AND unit  140  is simultaneously connected to respective first inputs of AND gates  150 B 4 ,  150 C 4 ,  150 D 4  and  150 E 4 .  
         [0031]    The output QB of the bi-directional shift register  160  is simultaneously connected to respective second inputs of AND gates  150 B 1 ,  150 B 2 ,  150 B 3  and  150 B 4 ; the output QC of the bi-directional shift register  160  is simultaneously connected to respective second inputs of AND gates  150 C 1 ,  150 C 2 ,  150 C 3 ,  150 C 4 ; the output QD of the bi-directional shift register  160  is simultaneously connected to respective second inputs of AND gates  150 D 1 ,  150 D 2 ,  150 D 3 ,  150 D 4 ; and the output QE of the bi-directional shift register  160  is simultaneously connected to respective second inputs of AND gates  150 E 1 ,  150 E 2 ,  150 E 3 ,  150 E 4   
         [0032]    Accordingly, for example, in order for the first and the second nozzles of nozzle group QC to be fired simultaneously, the first logic AND unit outputs a “1” at S 1  and S 2 , the selection signal QC is output as “1” from the bi-directional shift register  160 , and the second logic AND unit outputs a “1” at the outputs of AND gates  150 C 1  and  150 C 2 . The first logic AND unit  140  is provided with as many AND gates as the groups of head nozzles, and the groups of head nozzles are connected to the nozzle group selection signals QB to QE of the bi-directional shift register  160  respectively via the second AND unit  150 .  
         [0033]    The nozzle groups are selected in an order B C D E or E D C B according to the signal dir output from the first memories  120 . A summary of the logic operations of the second AND unit  150  is shown in FIG. 3.  
         [0034]    [0034]FIG. 4 is a flow chart for explaining a method for transmitting serial data/addresses for a printer head according to an embodiment of the present invention.  
         [0035]    As shown in FIG. 4, the data processor  100  generates and supplies data determining simultaneous firing nozzles and a nozzle group firing direction (S 210 ). The simultaneous firing nozzles are selected based on the data provided through the fire/group direction data line  110 . The data provided through the fire/group direction data line  110  to the first memories  120  are latched at operation  220  in synchronization with the shift clock  111  generated from the data processor  100 . Data for firing the simultaneous firing nozzles are stored in the second memories  130  in synchronization with the output of the first memories  120  and the latch clock provided through the latch clock line  112  of the data processor  100 . The bi-directional shift register  160  outputs signals selecting nozzle groups(for example, four groups in the embodiment) from the outputs of the nozzle group selection signals QA to QF as the inputs of the second AND unit  150  in synchronization with a latch clock provided from the latch clock line  112  at operation  230 . Meanwhile, a generated fire pulse signal is supplied through the fire pulse line  113  at operation S 240 . The simultaneous firing nozzle data outputted from the second memories  130  is ANDed in the first logic AND unit  140  in synchronization with the fire pulse line  113  provided from the data processor  100  so that the simultaneous firing nozzles are selected at operation S 250 . Accordingly, the second AND unit  150  ANDs the outputs of the first logic AND unit  140  and the nozzle group selection signals (QB-QE) of the bi-directional shift register  160 . Each output of the second AND unit  150  is applied to a gate of an FET driving a respective nozzle so that the selected nozzle is fired at operation S 260 . Further, printing is completed with the repetitive performance of operations S 210  through S 260 .  
         [0036]    As stated above, the present invention simplifies the connections with the minimized interface signals between the printer head and the printer main body to prevent malfunctions, and simplifies logic operations in the printer head to minimize the size of the logic unit for the printer head.  
         [0037]    Although 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 this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.