Patent ID: 8472069

Claim:
A dot position measurement method, comprising: a line pattern forming step of forming a measurement line pattern including a plurality of lines formed by dot sequences corresponding to respective recording elements on a recording medium, by continuously recording dots by the recording elements while causing a recording head having the recording elements and the recording medium to move relatively to each other in a relative movement direction, the measurement line pattern including a plurality of line blocks each constituted of a group of lines to be recorded using the recording elements spaced a prescribed interval apart in an effective direction of alignment of the recording elements which is perpendicular to the relative movement direction, the line blocks being formed at mutually different positions in a lengthwise direction of the lines on the recording medium; a reading step of reading the measurement line pattern formed on the recording medium in the line pattern forming step by an image reading device, and acquiring electronic image data representing a read image of the measurement line pattern; a position-in-line-block identifying step of identifying line positions in each of the line blocks, from the read image acquired in the reading step; a function determination step of providing a temporary recording element number corresponding to the line positions within each of the line blocks starting from one of ends of the group of lines at the line block, to each of the line positions, and obtaining a function representing a relationship between the temporary recording element number and the line positions for each of the line blocks; a determination step of determining whether there is an error in the temporary recording element number for each of the line blocks, between the line blocks, in accordance with the function obtained for each of the line blocks; and a recording element position specifying step of changing the temporary recording element number of at least one of the line blocks which is determined to have the error in the temporary recording element number in the determination step, and specifying a correspondence relation between the line positions within each of the line blocks and the recording elements.