Method for detecting surface potential of image bearing member and image forming apparatus
AssigneeCanon Kabushiki Kaisha
InventorShiro Sakata
Life of this patent
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Abstract
An image forming apparatus configured to, in a state where a voltage is applied to a charging unit, determine a surface potential of an image bearing member using a first voltage applied when a current value obtained by, after applying a predetermined voltage to a transfer unit, detecting the current value while changing the applied voltage to a positive direction reaches a discharge current value, and a second voltage applied to the transfer unit when a current value obtained by, after applying the predetermined voltage to the transfer unit, detecting the current value while changing the applied voltage to a negative direction reaches the discharge current value.
Claims14
An image forming apparatus comprising:
- an image bearing member on which an image is formed;
- a charging unit configured to charge the image bearing member;
- a transfer unit configured to transfer the image formed on the image bearing member onto a transfer member;
- a first voltage application unit configured to apply a predetermined voltage to the charging unit so that the image bearing member becomes charged to a predetermined potential;
- a second voltage application unit configured to apply a voltage to the transfer unit;
- and
- a current detection unit configured to detect a current flowing to the image bearing member via the transfer unit when a voltage is applied to the transfer unit,
- wherein a surface potential of the image bearing member is determined based on information on a difference between a first voltage and a second voltage, the first voltage being applied from the second voltage application unit to the transfer unit when a value detected by the current detection unit, after the second voltage application unit applies a voltage to the transfer unit while changing the voltage from the predetermined voltage to a lower potential side, reaches a value indicating a start of discharge between the image bearing member and the transfer unit, and the second voltage being applied from the second voltage application unit to the transfer unit when a value detected by the current detection unit, after the second voltage application unit applies a voltage to the transfer unit while changing the voltage from the predetermined voltage to a higher potential side, reaches a value indicating the start of discharge between the image bearing member and the transfer unit.
A method for detecting a surface potential of an image bearing member on which an image is formed, the method comprising:
- applying a predetermined voltage to a charging unit configured to charge the image bearing member;
- detecting a first voltage being applied from a voltage application unit to a process member when a value detected by a current detection unit, after applying a voltage to a transfer unit while changing the voltage from a predetermined voltage to a lower potential side, reaches a value indicating a start of discharge between the image bearing member and the transfer unit;
- detecting a second voltage being applied from the voltage application unit to the transfer unit when a value detected by the current detection unit, after applying the voltage to the transfer unit while changing the voltage from the predetermined voltage to a higher potential side, reaches a value indicating the start of discharge between the image bearing member and the transfer unit;
- and
- determining a surface potential of the image bearing member based on information on a difference between the first voltage and the second voltage.
A voltage output device configured to output a voltage to a transfer unit which acts on an image bearing member comprising:
- a voltage application unit configured to apply the voltage to the transfer unit;
- a current detection unit configured to detect a value corresponding to a current flowing to the transfer unit when the voltage is applied to the transfer unit,
- wherein, a surface potential of the image bearing member is determined based on information on a difference between a first voltage and a second voltage, the first voltage being applied from the voltage application unit to the transfer unit when a value detected by the current detection unit, after the voltage application unit applies a voltage to the transfer unit while changing the voltage from a predetermined voltage to a lower potential side, reaches a value indicating a start of discharge between the image bearing member and the transfer unit, and the second voltage being applied from the voltage application unit to the transfer unit when a value detected by the current detection unit, after the voltage application unit applies the voltage to the transfer unit while changing the voltage from a predetermined voltage to a higher potential side, reaches a value indicating the start of discharge between the image bearing member and the transfer unit.
Dependencies are inferred from the claim text.