Patent ID: 7314260

Claim:
An inkjet print device which prints by reciprocally moving a carriage carrying a print head in a main scan direction while controlling ink ejection from the print head according to a carriage position both in a forward movement and in a return movement, said device comprising: position sensing means for sensing the carriage position; speed sensing means for sensing moving speed of the carriage; correction quantity determining means for presetting a relationship between a reference moving speed of the carriage and a reference positional correction quantity for correcting a discrepancy in an ink hitting position resulting from the ink ejection from the print head while the carriage is moving at the reference moving speed of the carriage, and for determining a positional correction quantity for correcting a discrepancy in an ink hitting position resulting from the ink ejection from the print head while the carriage is moving at the reference moving speed of the carriage, said correction quantity determining means determining the position correction quantity from the preset relationship and from the moving speed of the carriage sensed by the speed sensing means according to the preset relationship; and ejection control means for controlling the ink ejection from the print head according to the positional correction quantity determined by the correction quantity determining means and the carriage position sensed by the position sensing means, wherein: the position sensing means contains an encoder producing a pulse signal output according to a displacement of the carriage; the speed sensing means contains time measurement means for measuring a cycle of the pulse signal output from the encoder; and the correction quantity determining means presets a relationship between the cycle of the pulse signal output corresponding to the reference moving speed and the reference positional correction quantity and determines the positional correction quantity from the preset relationship and from the cycle of the pulse signal output measured by the time measurement means, wherein the relationship between the cycle of the pulse signal output corresponding to the reference moving speed and the reference positional correction quantity is an inversely proportional relationship, and wherein the correction quantity determining means prestores a correction quantity table representing a relationship between multiple cycles of the pulse signal output and multiple positional correction quantities and determines the positional correction quantity from the cycle of the pulse signal output measured by the time measurement means in the speed sensing means in reference to the correction quantity table.