Typewriting machines – Including control of format by programmed-control-system
Reexamination Certificate
1998-12-18
2001-07-17
Hilten, John S. (Department: 2854)
Typewriting machines
Including control of format by programmed-control-system
C400S070000, C400S061000, C400S120020
Reexamination Certificate
active
06261010
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a printing apparatus and a print control method. More particularly, the present invention relates to a printing apparatus having a printhead and a buffer memory for storing image data, and a print control method for transferring image data stored in the buffer memory to a printhead and printing an image on a print medium.
In a conventional print operation of a so-called serial printer, at least one buffer memory is employed to store image data for an image area printed by a single scan of a printhead, and an image is printed on a print medium by transferring the image data directly from the buffer memory to the printhead (hereinafter, such buffering method will be referred to as “scan-based buffering”). Moreover, in a case of using a color printer comprising a printhead, in which a plurality of head units are each provided for respective colors, and have the same number of pixels (same print width), are arrayed in the scanning direction, the similar scan-based buffering is employed.
Because of large-scale integration of logical circuits and downsizing of a printhead, the latest printers employ a printhead in which a plurality of head units corresponding to respective colors are arrayed in a line in the print paper conveyance direction. In the printer employing such a printhead, the positions of dots, printed each time the printhead is scanned, are different for each color with respect to the print paper conveyance direction. Therefore, buffer memory management becomes complicated in the aforementioned scan-based buffering. In view of this, complications buffer memories having different sizes are provided for each of the colors, and a method (hereinafter referred to as “scroll buffering”) where a buffer controller scrolls the buffer memories corresponding to each color is employed.
However, the scan-based buffering is limited in terms of its application depending on the type of the printhead as described above. For instance, the scanbased buffering is difficult to apply to a printhead whose plural head units corresponding to respective colors are arrayed a in line in the print paper conveyance direction. Meanwhile, in the scroll buffering, since buffers are fixedly provided for respective colors, for instance, in a case where image printing is performed by using black only, buffers provided for other colors are wasted. Thus, it raises a problem of inefficient usage of buffer memories.
Furthermore, multi-pass printing for printing an image by scanning a printhead for the same area plural times has a disadvantage of complicated control. Moreover, since the conveyance amount of the print medium must be constant for each scan of the printhead, the print speed cannot be increased.
SUMMARY OF THE INVENTION
The present invention is made in consideration of the above situation, and has as its object to provide a printing apparatus and a print control method which can efficiently utilize a buffer memory.
According to one aspect of the present invention, the foregoing object is attained by providing a print control method for performing a print operation by controlling a scan operation of a color printhead and a plurality of buffer memories where color image data is temporarily stored in units of each color component, comprising: an input step of inputting color component data to the plurality of buffer memories; a monitoring step of monitoring data storage with respect to the plurality of memories; a discriminating step of discriminating whether or not at least one of the plurality of buffer memories has become full based on a monitoring result in the monitoring step; a determining step of dynamically determining a print width, a conveyance amount of a print medium, and color component data to be cleared upon printing, based on a printable width of the color printhead and contents of the inputted color component data; a printing step of performing printing on the print medium by scanning the color printhead based on a discrimination result in the discriminating step and the print width determined in the determining step; a conveying step of conveying the print medium for the conveyance amount determined in the determining step; and a releasing step of clearing the color component data, determined in the determining step, from the plurality of buffer memories.
Furthermore, in a case where the print operation is performed by multi-pass printing, where printing is executed by scanning the color printhead plural times for the same area on the print medium, the discriminating step discriminates whether or not data storage with respect to each of the plurality of buffer memories has reached a predetermined amount, and the determining step determines the conveyance amount and color component data to be cleared, taking into account a number of times of scan of the color printhead for the same area.
According to another aspect of the present invention, the foregoing object is attained by providing a printing apparatus for performing a print operation by controlling a scan operation of a color printhead and a plurality of buffer memories where color image data is temporarily stored in units of each color component, comprising: input means for inputting color component data to the plurality of buffer memories; monitoring means for monitoring data storage with respect to the plurality of memories; discriminating means for discriminating whether or not at least one of the plurality of buffer memories has become full based on a monitoring result by the monitoring means; determining means for dynamically determining a print width, a conveyance amount of a print medium, and color component data to be cleared upon printing, based on a printable width of the color printhead and contents of the inputted color component data; printing means for performing printing on the print medium by scanning the color printhead based on a discrimination result of the discriminating means and the print width determined by the determining means; conveying means for conveying the print medium for the conveyance amount determined by the determining means; and releasing means for clearing the color component data, determined by the determining means, from the plurality of buffer memories.
Herein, in a case where the print operation is performed by multi-pass printing, and where printing is executed by scanning the color printhead plural times for the same area on the print medium, the discriminating means discriminates whether or not data storage with respect to each of the plurality of buffer memories has reached a predetermined amount, and the determining means determines the conveyance amount and color component data to be cleared, taking into account a number of times of scan of the color printhead for the same area.
According to an aspect of the present invention, the color image data is density data comprising black component data, cyan component data, magenta component data and yellow component data, the plurality of buffer memories includes a first buffer for storing the black component data, a second buffer for storing the cyan component data, a third buffer for storing the magenta component data, and a fourth buffer for storing the yellow component data, and the color printhead includes a first head unit for performing printing in black ink, a second head unit for performing printing in cyan ink, a third head unit for performing printing in magenta ink, and a fourth head unit for performing printing in yellow ink, each performing printing in correspondence with each component data of the density data stored in the first, second, third and fourth buffers, respectively.
For a configuration of the color printhead, it is preferable that a ratio of a print width with respect to the first head unit to the second, third and fourth head units is 3:1, and an array of ink discharge nozzles which discharge ink from each of the first, second, third and fourth head units is arranged in a print medium conveyance direction.
Furthermore, it is preferable that the first
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Hilten John S.
Nolan, Jr. Charles H.
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