Image reader, image forming apparatus, and image density correcting method

A density correcting method, comprising:

• controlling a reading device to read a color patch printed in advance on a recording medium;
• controlling a motor to drive both a first conveying roller pair having a first roller radius and a second conveying roller pair having a second roller radius larger than the first roller radius at a same angular speed so that a relative relation between a reading position of the reading device and the recording medium held by the first conveying roller pair located on an upstream side of the reading device in a conveyance direction of the recording medium and the second conveying roller pair located on a downstream side of the reading device in the conveyance direction of the recording medium is constant;
• and
• reading the color patch used for the density correction from the recording medium in a period in which the relative relation is constant.

A non-transitory recording medium storing computer-readable instructions, which when executed by a computer, cause the computer to perform a density correcting method, the method comprising:

• controlling a reading device to read a color patch printed in advance on a recording medium;
• controlling a motor to drive both a first conveying roller pair having a first roller radius and a second conveying roller pair having a second roller radium larger than the first roller radius at a same angular speed so that a relative relation between a reading position of the reading device and the recording medium held by the first conveying roller pair located on an upstream side of the reading device in a conveyance direction of the recording medium and the second conveying roller pair located on a downstream side of the reading device in the conveyance direction of the recording medium is constant;
• and
• reading the color patch used for the density correction from the recording medium in a period in which the relative relation is constant.