Ink jet printer and control method thereof

A control method of an ink jet printer having an ink jet head which ejects an ink droplet to record a dot on a recording sheet, the ink jet head being mounted on a carriage reciprocating in a direction substantially orthogonal to a conveying direction of the recording sheet, comprising the steps of:

• dividing an ejection time width for recording one dot of ink ejected from said ink jet head into a plurality of pitches;
• associating each pitch with an address of a timing data memory;
• preparing timing data by storing data indicating plural ejection time lengths of said ink jet head in the address corresponding to ejection timing;
• providing selection information for selecting any one of said plural ejection time lengths, said selection information being included in record data for each dot;
• determining the ejection timing for each dot from said timing data on the basis of the ejection time length selected by the selection information of said record data;
• and
• controlling each dot ink ejection time length by the determined ejection timing.

An ink jet printer in which an ink jet head is mounted on a carriage reciprocating in a direction substantially orthogonal to a conveying direction of a recording sheet, comprising:

• CPU for outputting record data including data indicating an ink ejection time length for each dot;
• a record data memory for sequentially storing a predetermined volume of record data while said ink jet head is moving along a recording path;
• a timing data memory for dividing an ejection time width for recording one dot of ink ejected from said ink jet head into a plurality of pitches, associating each pitch with an address position, and storing data indicating plural ejection time lengths in an address corresponding to ejection timing;
• a timing signal generating circuit for reading and outputting the record data for one dot from said record data memory, and for reading the ejection timing corresponding to the ejection time length indicated by said record data from said timing data memory to output an ejection signal at a predetermined ejection timing;
• and
• a head driver for operating the ink jet head based on said record data for one dot and said ejection signal to eject the ink corresponding to said record data at said predetermined ejection timing.