Image forming apparatus calculating an amount of deviation of an image forming position from a reference

An image forming apparatus calculating an amount of deviation of an image forming position from a reference, the amount of deviation being caused by thermal effect in the apparatus, the image forming apparatus comprising:

• an estimating unit for estimating the amount of deviation with time;
• a mark forming unit for forming a color deviation detection mark;
• a detecting unit for detecting reflected light upon irradiation of the formed color deviation detection mark with light;
• and
• a control unit for performing color deviation control to cause the mark forming unit to form the color deviation detection mark and cause the detecting unit to perform the detection if a parameter concerning an accumulated error of the amount of deviation estimated by the estimating unit reaches a first threshold value,
• wherein the color deviation control is performed at timing when the amount of deviation estimated by the estimating unit is estimated to reach a second threshold value that is set independently of the first threshold value, the image forming apparatus further comprising:
• a setting unit for setting the estimating unit so that an amount of deviation that is estimated becomes close to the amount of deviation that actually occurs on the basis of the amount of deviation detected at the timing and the amount of deviation estimated by the estimating unit.

An image forming apparatus comprising:

• an estimating unit for estimating an amount of deviation of an image forming position from a reference with time;
• a mark forming unit for forming a color deviation detection mark;
• a detecting unit for detecting reflected light upon irradiation of the formed color deviation detection mark with light;
• a control unit for causing the mark forming unit to form the color deviation detection mark and causing the detecting unit to detect the color deviation detection mark at timing when the amount of deviation estimated by the estimating unit is estimated to reach a threshold value;
• and
• a setting unit for setting the estimating unit so that the amount of deviation estimated by the estimating unit becomes closer to an amount of deviation that actually occurs based on the amount of deviation obtained from a result of detection by the detecting unit and the amount of deviation estimated by the estimating unit at timing when the amount of deviation is estimated to reach a threshold value.

An image forming apparatus comprising:

• an estimating unit for estimating an amount of deviation of an image forming position from a reference with time;
• a mark forming unit for forming a color deviation detection mark;
• a detecting unit for detecting reflected light upon irradiation of the formed color deviation detection mark with light;
• a control unit for performing color deviation control to cause the mark forming unit to form the color deviation detection mark and cause the detecting unit to detect the color deviation detection mark if a parameter concerning an accumulated error of the amount of deviation estimated by the estimating unit reaches a first threshold value;
• and
• a setting unit for setting the estimating unit so that the amount of deviation estimated by the estimating unit becomes closer to the amount of deviation that actually occurs on the basis of the amount of deviation obtained from a result of detection by the detecting unit and the amount of deviation estimated by the estimating unit at timing when the amount of deviation is estimated to reach a second threshold value.