Image forming apparatus that charges an image bearing member using a voltage set according to an environmental temperature

An image forming apparatus comprising:

• an image bearing member;
• a charging roller configured to come into contact with the image bearing member and charge the image bearing member when a voltage is applied;
• a charging power supply configured to apply, to the charging roller, a voltage in which a direct-current voltage and an alternating-current voltage are superimposed;
• a current detector configured to detect a current flowing through the charging roller when the charging power supply applies the voltage to the charging roller;
• a temperature detector configured to detect an environmental temperature;
• and
• a controller configured to control the charging power supply, wherein
• the controller performs, in a case where an absolute value of a difference between a previous temperature detected by the temperature detector and a current temperature detected by the temperature detector is equal to or higher than a predetermined threshold, and the current temperature detected by the temperature detector is equal to or higher than a predetermined temperature, first control of controlling the charging power supply to apply, to the charging roller, a voltage at which the current detected by the current detector has a predetermined current value,
• the controller performs, in a case where the absolute value of the difference is equal to or higher than the predetermined threshold, and the current temperature detected by the temperature detector is lower than the predetermined temperature, second control of controlling the charging power supply to apply, to the charging roller, a predetermined voltage,
• the controller performs, in a case where the absolute value of the difference is lower than the predetermined threshold, and the first control is previously performed, third control of controlling the charging power supply to apply, to the charging roller, a voltage obtained by offsetting a first correction value with respect to a value of the voltage previously applied to the charging roller,
• the controller performs, in a case where the absolute value of the difference is lower than the predetermined threshold, and the second control is previously performed, fourth control of controlling the charging power supply to apply, to the charging roller, a voltage obtained by offsetting a second correction value with respect to a value of the voltage previously applied to the charging roller, and
• an absolute value of the second correction value when the previous temperature detected by the temperature detector is a first temperature and the current temperature detected by the temperature detector is a second temperature different from the first temperature is larger than an absolute value of the first correction value when the previous temperature detected by the temperature detector is the first temperature and the current temperature detected by the temperature detector is the second temperature.