Image forming apparatus and control program

A non-transitory recording medium storing a computer readable control program to be executed by a computer of an image forming apparatus to determine a state of a rotary member included in the image forming apparatus, the control program causing the computer to execute:

• a step of causing an image forming unit to form an image pattern on a medium, a predetermined image repeatedly appearing in a first cycle in a sub scanning direction in the image pattern;
• a step of causing an optical sensor to optically detect a density of the image pattern in the sub scanning direction;
• a step of determining whether a feature image having a second cycle corresponding to the first cycle is detected, in accordance with a result of the detection performed by the optical sensor;
• a step of determining whether a cycle depending on an outer circumference of the rotary member corresponds to the second cycle, when the feature image is detected in the second cycle;
• and
• a step of determining that the state of the rotary member has deteriorated, when the cycle depending on the outer circumference of the rotary member is determined to correspond to the second cycle.

An image forming method comprising:

• an image forming step of forming an image pattern on a medium, a predetermined image repeatedly appearing in a first cycle in a sub scanning direction in the image pattern;
• a density detecting step of optically detecting a density of the image pattern in the sub scanning direction;
• a cyclic image detecting step of detecting a feature image having a second cycle corresponding to the first cycle, in accordance with a result of the detection performed in the density detecting step;
• and
• a state determining step of determining whether a cycle depending on an outer circumference of a rotary member included in the image forming apparatus corresponds to the second cycle when the feature image is detected in the cyclic image detecting step, and determining that a state of the rotary member has deteriorated when the cycle depending on the outer circumference is determined to correspond to the second cycle.

A control method for determining a state of a rotary member included in an image forming apparatus, the control method comprising:

• a step of causing an image forming unit to form an image pattern on a medium, a predetermined image repeatedly appearing in a first cycle in a sub scanning direction in the image pattern;
• a step of causing an optical sensor to optically detect a density of the image pattern in the sub scanning direction;
• a step of determining whether a feature image having a second cycle corresponding to the first cycle is detected, in accordance with a result of the detection performed by the optical sensor;
• a step of determining whether a cycle depending on an outer circumference of the rotary member corresponds to the second cycle, when the feature image is detected in the second cycle;
• and
• a step of determining that the state of the rotary member has deteriorated, when the cycle depending on the outer circumference of the rotary member is determined to correspond to the second cycle.