| 摘要 |
PROBLEM TO BE SOLVED: To reduce the possibility that a stripe-shaped image extending in a main scanning direction appears in an image read by a contact type image sensor.SOLUTION: An image reading device includes: a switching power supply for supplying power supply voltages to a plurality of loads; and a contact type image sensor, a read control unit and a period control unit which are loads. The read control unit allows a light receiving element present on the outside of an image reading area to output a light receiving voltage obtained when reading a line just before a reading target line at first timing in a line period, and then allows the light receiving element present on the outside of the image reading area to output a light receiving voltage at second timing, adopts a difference between the two light receiving voltages as a reference voltage, and indicates respective differences between respective light receiving voltages outputted from respective light receiving elements in an image reading area and the reference voltage as density values of respective pixels in the reading target line. The period control unit changes a switching period so that a difference between power supply voltages supplied by the switching power supply at the first timing and the second timing does not coincide with a difference between a maximum value and a minimum value of the power supply voltages. |
