Recording head adjustment method and image recording apparatus

A recording head adjustment method comprising:

• a dot row forming step of causing relative movement between a recording medium and a recording head in which a plurality of sub-heads each including a plurality of recording elements are joined together, and driving the plurality of recording elements at prescribed drive timing with respect to each of the plurality of sub-heads in such a manner that dot rows for the respective sub-heads are formed in a direction substantially perpendicular to a direction of the relative movement;
• a step-difference amount calculation step of measuring positions in the direction of the relative movement of the dot rows formed by the respective sub-heads are measured by taking, as a measurement object, a region formed by using the recording elements belonging to a central portion including the central recording element in the direction of the relative movement, and obtaining an amount of step difference between the sub-heads represented by difference or ratio of the measured positions in the direction of the relative movement of the dot rows for the respective sub-heads;
• an adjustment value calculation step of calculating an adjustment value for the drive timing of the plurality of recording elements with respect to each of the plurality of sub-heads according to the obtained amount of step difference;
• and
• a drive timing adjustment step of adjusting relative drive timing with respect to each of the plurality of sub-heads according to the calculated adjustment value, wherein:
• in the dot row forming step, a plurality of first dot rows in the direction substantially perpendicular to the direction of the relative movement are formed at a prescribed arrangement interval in the direction of the relative movement by using one sub-head of the mutually adjacent sub-heads, and a second dot row in the direction substantially perpendicular to the direction of the relative movement is formed between the plurality of first dot rows by using the other sub-head of the mutually adjacent sub-heads, and
• in the step-difference amount calculation step, the amount of step difference between the mutually adjacent sub-heads is calculated according to measurement result of measuring pitches between the plurality of first dot rows and the second dot row.

An image recording apparatus comprising:

• a recording head having a structure in which a plurality of sub-heads each including a plurality of recording elements are joined together;
• a recording head drive device which causes relative movement between a recording medium and the recording head and drives the plurality of recording elements at prescribed drive timing with respect to each of the plurality of sub-heads;
• a drive control device which controls the recording head drive device to form dot rows for the respective sub-heads, the dot rows extending in a direction substantially perpendicular to a direction of the relative movement;
• a step-difference amount calculation device which measures positions in the direction of the relative movement of the dot rows for the respective sub-heads in a situation where a range of a part of the dot rows formed by an overlapping portion between the mutually adjacent sub-heads where recording rates represented by number of dots per unit surface area are substantially same as each other is set as a measurement object, and obtains an amount of step difference between the sub-heads represented by difference or ratio of the measured positions in the direction of the relative movement of the dot rows for the respective sub-heads;
• an adjustment value calculation device which calculates an adjustment value for the drive timing of the plurality of recording elements with respect to each of the plurality of sub-heads according to the obtained amount of step difference;
• and
• a drive timing adjustment device which adjusts relative drive timing with respect to each of the plurality of sub-heads according to the calculated adjustment value, wherein:
• a plurality of first dot rows in the direction substantially perpendicular to the direction of the relative movement are formed at a prescribed arrangement interval in the direction of the relative movement by using one sub-head of the mutually adjacent sub-heads, and a second dot row in the direction substantially perpendicular to the direction of the relative movement is formed between the plurality of first dot rows by using the other sub-head of the mutually adjacent sub-heads, and
• the amount of step difference between the mutually adjacent sub-heads is calculated according to a result of measuring pitches between the plurality of first dot rows and the second dot row.

An image recording apparatus comprising:

• a recording head having a structure in which a plurality of sub-heads each including a plurality of recording elements are joined together;
• a recording head drive device which causes relative movement between a recording medium and the recording head and drives the plurality of recording elements at prescribed drive timing with respect to each of the plurality of sub-heads;
• a drive control device which controls the recording head drive device to form dot rows for the respective sub-heads, the dot rows extending in a direction substantially perpendicular to a direction of the relative movement;
• a step-difference amount calculation device which measures positions in the direction of the relative movement of the dot rows formed by the respective sub-heads are measured by taking, as a measurement object, a region formed by using the recording elements belonging to a central portion including the central recording element in the direction of the relative movement, and obtains an amount of step difference between the sub-heads represented by difference or ratio of the measured positions in the direction of the relative movement of the dot rows for the respective sub-heads;
• an adjustment value calculation device which calculates an adjustment value for the drive timing of the plurality of recording elements with respect to each of the plurality of sub-heads according to the obtained amount of step difference;
• and
• a drive timing adjustment device which adjusts relative drive timing with respect to each of the plurality of sub-heads according to the calculated adjustment value, wherein:
• a plurality of first dot rows in the direction substantially perpendicular to the direction of the relative movement are formed at a prescribed arrangement interval in the direction of the relative movement by using one sub-head of the mutually adjacent sub-heads, and a second dot row in the direction substantially perpendicular to the direction of the relative movement is formed between the plurality of first dot rows by using the other sub-head of the mutually adjacent sub-heads, and
• the amount of step difference between the mutually adjacent sub-heads is calculated according to measurement result of measuring pitches between the plurality of first dot rows and the second dot row.