Method and apparatus for correcting printhead, printhead corrected by this apparatus, and printing apparatus using this printhead

A printhead corrected by a method of correcting a printing characteristic of said printhead, said printhead having a plurality of printing elements and a memory unit for storing data, said method comprising:

• a testing step of performing experimental printing on a recording medium using the printhead;
• a detecting step of detecting a variation in density per a predetermined area of an image that has been printed on the recording medium, wherein the predetermined area is defined by N pixels in a first direction in which the plurality of printing elements are arrayed and M pixels in a second direction different from the first direction;
• a correction-data generating step of generating, per the plurality of printing elements, correction data for correcting the variation in density detected in said detecting step;
• and
• a writing step of writing the correction data in the memory unit of the printhead,
• wherein N is a positive integer greater than 1 and less than 9,
• M is a positive integer greater than 15 and less than 1025,
• dots are formed in the predetermined area by sampling pixels, and
• a resolution per N pixels is less than 300 dpi.

A printing apparatus using a printhead corrected by a method of correcting a printing characteristic of said printhead, said printhead having a plurality of printing elements and a memory unit for storing data, said method comprising a testing step of performing experimental printing on a recording medium using the printhead, a detecting step of detecting a variation in density per a predetermined area of an image that has been printed on the recording medium, wherein the predetermined area is defined by N pixels in a first direction in which the plurality of printing elements are arrayed and M pixels in a second direction different from the first direction, a correction-data generating step of generating, per the plurality of printing elements, correction data for correcting the variation in density detected in said detecting step, and a writing step of writing the correction data in the memory unit of the printhead, said apparatus comprising:

• receiving means for receiving the correction data from the printhead;
• generating means which, on the basis of the correction data, generates a control signal for controlling operation of drive means in such a manner that the plurality of printing elements form uniform pixels;
• and
• transmitting means for transmitting the control signal to the printhead,
• wherein N is a positive integer greater than 1 and less than 9,
• M is a positive integer greater than 15 and less than 1025,
• dots are formed in the predetermined area by sampling pixels, and
• a resolution per N pixels is less than 300 dpi.

A method of correcting a printing characteristic of a printhead having a plurality of printing elements and a memory unit for storing data, said method comprising:

• a testing step of performing experimental printing on a recording medium using the printhead;
• a detecting step of detecting a variation in density per a predetermined area of an image that has been printed on the recording medium, wherein the predetermined area is defined by N pixels in a first direction in which the plurality of printing elements are arrayed and M pixels in a second direction different from the first direction;
• a correction-data generating step of generating, per the plurality of printing elements, correction data for correcting the variation in density detected in said detecting step;
• and
• a writing step of writing the correction data in the memory unit of the printhead,
• wherein N is a positive integer greater than 1 and less than 9,
• M is a positive integer greater than 15 and less than 1025,
• dots are formed in the predetermined area by sampling pixels, and
• a resolution per N pixels is less than 300 dpi.