Canon Kabushiki Kaisha

Masanori Shida

Masaru Hibino

Ichiro Ozawa

Yoshiaki Kobayashi

Tohru Nakaegawa

Tatsuomi Murayama

Kenji Okado

Ryoichi Fujita

Kazumi Yoshizaki

In an image forming apparatus including a power source for forming a secondary-transfer electric field at a secondary-transfer position and for forming a primary-transfer electric field at a primary-transfer position by applying a voltage to a transfer member to pass a current through a constant-voltage element, a potential of an image portion is controlled depending on a detection result of a detecting member.

Image forming apparatus with common power source for primary transfer and secondary transfer

In a constitution in which a power source exclusively for primary-transfer is omitted and a predetermined voltage is generated in an intermediary transfer member, in a test mode in which a test voltage is applied to a secondary-transfer member in advance in order to obtain a proper secondary transfer voltage, in the case where the test voltage is low, a proper secondary-transfer voltage cannot be obtained in some cases. In a period of the test mode, the power source is controlled in order to maintain a Zener breakdown voltage, so that the proper secondary-transfer voltage can be obtained.

Image forming apparatus with constant voltage element for secondary transfer of toner image

In a constitution of primary-transfer-high-voltage-less in which a power source dedicated to primary-transfer, in the case where voltage applications for determining primary-transfer and secondary-transfer voltages are carried out concurrently, there is a possibility of improper primary-transfer. The possibility is decreased by controlling a power source so that a voltage drop of a Zener diode maintains a Zener breakdown voltage.

Image forming apparatus

Image forming apparatus that controls potential of electrostatic image forming portion depending on ambient condition

In a constitution in which a power source exclusively for primary transfer is omitted and a predetermined voltage is generated in an intermediary transfer member by a constant-voltage element, a high power source voltage more than necessary is applied in order to avoid primary transfer defect, so that a transfer member is deteriorated by energization in some cases. By detecting a current flowing into the constant-voltage element, it becomes possible to obtain a minimum power source voltage at which the intermediary transfer member is capable of maintaining a predetermined voltage, so that it is possible to avoid the energization deterioration of the transfer member.

Image forming apparatus with intermediate transfer member having constant voltage element

A controller controls a voltage to be applied to the transfer member when there is a recording material having a predetermined largest width at a secondary-transfer position, so that a constant-voltage element maintains a predetermined voltage, whereby it is possible to prevent transfer defect due to short of a primary-transfer electric field at a primary-transfer portion when a toner image is secondary-transferred onto the recording material.

An image forming apparatus includes an image carrier configured to carry a toner image, a movable belt member configured to convey a recording material, a transfer member configured to electrostatically transfer the toner image formed on the image carrier to the recording material conveyed by the belt material, and a plurality of auxiliary separation members configured to separate the recording material from the belt member such that the belt member positioned more downstream than the transfer member in the direction in which the recording material is conveyed is boosted from the inside of the belt member to locally protrude the belt surface of the belt member in the width direction, wherein the auxiliary separation members can move correspondingly to the size of the conveyed recording material in the width direction to the position where the ends of the recording material pass in the width direction.

Electrophotographic image forming apparatus

An image forming apparatus includes an image bearing member; a toner image forming portion for forming a toner image on the image bearing member; a rotatable belt member, stretched by a plurality of stretching members, for carrying and conveying a recording material; a transfer member for transferring the toner image from the image bearing member onto the recording material; a bias applying portion for applying a bias for transferring the toner image from the image bearing member onto the recording material; a push-up member for pushing up the belt member from an inner surface side of the belt member, perpendicular to a recording material conveyance direction; and an execution portion executing an operation in which the recording material is separated from the belt member by a push-up operation, which is performed, during rotation of the belt member, before the bias is applied to the transfer member.

Image forming apparatus with belt member push-up feature

An image forming apparatus includes an image bearing member; a transfer member for transferring a toner image from the image bearing member onto a transfer material at a transfer portion; a control portion for controlling a voltage to be applied to the transfer member; a current detecting portion for detecting a value of a current passing through the transfer portion; a calculating portion for calculating a relationship between values of the voltage and the current obtained by applying voltages of different values at different intervals between adjacent images during execution of a continuous image forming mode in which the images are continuously formed on recording materials; a determining portion for determining the voltage value for a target current from the calculated relationship; and a switching portion for switching the voltage value to the voltage value determined by the determining portion during the execution of the continuous image forming mode.

An image forming apparatus includes an image bearing member; toner image forming means for forming a toner image on the image bearing member; a transfer member for transferring the toner image from the image bearing member onto a recording material; an executing portion for executing a first cleaning mode in which the transfer member is cleaned by being supplied with a voltage of an identical polarity to a normal charge polarity of toner during non-image formation and executing a second cleaning mode in which the transfer member is cleaned by being supplied with a voltage of an opposite polarity to the normal charge polarity of the toner during the non-image formation; and a control portion for changing a ratio between a first cleaning mode execution period and a second cleaning mode execution period depending on an operation environment of the image forming apparatus.

In an image forming apparatus, temporary constant voltages are corrected by using three voltage-current data obtained by applying voltages at three levels to a primary transfer roller to detect currents corresponding to the voltages, respectively. A surface potential of a photosensitive drum is detected by a potential sensor by changing an exposure intensity of an exposure device at three levels in a state in which the temporary constant voltage is applied to the primary transfer roller. A constant voltage during image formation is determined by correcting the temporary constant voltage by using three voltage-current data obtained by detecting currents when surfaces different in potential by light exposure pass through a primary transfer portion.

Image forming apparatus with controller for setting transfer member bias

Provided is an image forming apparatus, including: a first image bearing member; a first transfer member that comes into contact with the intermediate transfer member; a colored toner image forming portion; a second image bearing member; a second transfer member; and a transparent toner image forming portion for forming the transparent toner image wherein the transparent toner image forming portion is provided on an upstream side with respect to the colored toner image forming portion in a movement direction of the intermediate transfer member, and a distance between a most upstream end of the second contact area and the second transfer member in a rotation direction is larger than a distance between a most upstream end of the first contact area and the first transfer member in a rotation direction.

An image forming apparatus for reducing time required for adjusting the image forming conditions and transport conditions and minimizing the number of recording material used for the adjustment. Image forming conditions and transport conditions for the recording material are adjusted according to the characteristic properties of the recording material. Associated data including an adjustment value obtained from the adjustment of the image forming conditions and transport conditions made by the adjustment unit and the characteristic properties of the recording material associated with the adjustment value is generated. The associated data stored in the storage unit is transmitted to the data collection/delivery apparatus. Delivery data regarding the adjustment of the image forming conditions and transport conditions is received from the data collection/delivery apparatus.

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Abiko, Japan

Masanori Shida