System for generating clock pulse which the number of pulses outputted within a predetermined time period is based on the number of calculated delay stages

An image forming apparatus, comprising:

• an image forming device to scan in a main scanning direction in synchronization with dot clock pulses for each scanning line so as to form an image;
• a basic clock pulse generating section to generate basic lock pulses with a predetermined interval;
• a delayed clock pulse generating section to generate a group of plural delayed clock pulses having different phases respectively by delaying the basic clock pulse generate by the basic clock pulse generating section into plural delay stages;
• a synchronism detecting section to detect at least two delayed clock pulses synchronizing with an index signal from the plural delayed clock pulses generated by said delayed clock pulse generating section;
• a calculating section to calculate a number of delay stages existing within a given time period on the basis of the two synchronizing delayed clock pulses detected by the synchronism detecting section;
• and
• a clock pulse control section to select the delayed clock pulses sequentially delayed from the synchronizing delayed clock pulse from the group of plural delayed clock pulses within a predetermined time period on the basis of the calculated number of delay stages so as to control a number of clock pulses outputted as the dot clock pulses during the predetermined time period.