| 摘要 |
An image forming apparatus includes an image bearing member, a transfer member, a voltage source, a speed setting portion, a test mode executing portion, a renewing mode executing portion, and a setting portion for setting a voltage applied to the transfer member, in a period in which the toner image exists at the transfer portion when image formation is executed at a first speed, at a first target voltage last renewed and for setting the voltage applied to the transfer member, in a period in which the toner image exists at the transfer portion when the image formation is executed at a second speed, at a voltage on the basis of the first target voltage last renewed and a conversion coefficient last renewed. |
| 主权项 |
1. An image forming apparatus comprising:
an image bearing member for bearing a toner image; a transfer member for forming a transfer portion where the toner image is transferred from said image bearing member onto an intermediary transfer member; a voltage source for applying a voltage to said transfer member; a speed setting portion for setting a speed of said image bearing member at either one of speeds including a first speed and a second speed different from the first speed; a test mode executing portion for executing an operation in a test mode in which the speed of said image bearing member is set at a predetermined speed and a target voltage at which a predetermined target current corresponding to the predetermined speed is obtained from a relationship between a voltage and a current when the voltage is applied to said transfer member in a period in which the toner image does not exist at the transfer portion; a renewing mode executing portion for executing an operation in a voltage renewing mode in which a first target voltage is obtained by executing the operation in the test mode at the first speed and then is renewed and for executing an operation in a conversion coefficient renewing mode in which a second target voltage is obtained by executing the operation in the test mode at the second speed and a conversion coefficient is obtained from the first target voltage last renewed and the second target voltage and then is renewed, wherein said renewing mode executing portion executes the operation in the voltage remaining mode at a frequency higher than a frequency of the operation in the conversion coefficient renewing mode; and a setting portion for setting a voltage applied to said transfer member, in a period in which the toner image exists at the transfer portion when image formation is executed at the first speed, at the first target voltage last renewed and for setting the voltage applied to said transfer member, in a period in which the toner image exists at the transfer portion when the image formation is executed at the second speed, at a voltage on the basis of the first target voltage last renewed and the conversion coefficient last renewed. |
