Canon Kabushiki Kaisha

Kenichi Shibuya

Atsushi Takeda

Yoshiyuki Komiya

Fumiteru Gomi

Kouichi Hashimoto

Shuichi Kadota

Sumito Tanaka

Hiroyuki Eda

Hirohisa Nakajima

Jun Tomine

Shota Soda

Takayuki Ganko

An image forming apparatus includes an intermediary transfer member, image forming units, a voltage source, an executing portion, a setting portion, and a selecting portion configured to select a first mode or a second mode. In the first mode, each of exposure amounts of first and second exposure members is set so that a maximum toner amount per unit area during execution of an image forming operation is a first amount per unit area and a pre-exposure amount is set at a first pre-exposure amount. In the second mode, each of the exposure amounts is set so that the maximum toner amount per unit area is a second amount per unit area smaller than the first amount per unit area, and the pre-exposure amount is set at a second pre-exposure amount larger than the first pre-exposure amount.

Image forming apparatus

In an image forming apparatus including a plurality of image forming stations, on the basis of a density of a toner image formed in an upstream image forming station, an operation of a pre-exposure device in a downstream image forming station is controlled.

Image forming apparatus with pre-exposure member

In an image forming apparatus including a plurality of image forming stations, a pre-exposure device is not provided in at least a most upstream image forming station at which a toner image formed by the image forming station cannot arrive, and the pre-exposure device is provided in at least a most downstream image forming station at which the toner image formed by the image forming station can arrive.

An image forming apparatus capable of suppressing a charging lateral stripe liable to generate at a last stage of a lifetime of a photosensitive member while suppressing a density fluctuation is provided. A constitution which includes a photosensitive member, a charging portion, a charging voltage source S, an exposure portion, a developing portion, an obtaining portionfor obtaining information relating to a cumulative operating amount and a controllerfor effecting control so that a discharging operation for discharging the photosensitive memberby exposing the photosensitive memberto light by the exposure portionis executed is used.

Image forming apparatus with exposure controlled in dependence on cumulative operating time and humidity

An image forming apparatus includes a first toner image forming unit including a rotatable photosensitive drum and a charger and configured to form a first toner image on the drum, the charger being supplied with a DC voltage to charge; a movable intermediary transfer member supplied with a transferring current for transferring the first image from the drum onto the transfer member, the transfer member carrying a second toner image at a position upstream of the transfer portion; and a switching portion for switching a mode from a first mode in which a maximum toner deposition amount of the second image fed to the transfer portion and a transfer current supplied to the transfer member are set at respective standard levels to a second mode in which the toner deposition amount and the transferring current are set at respective predetermined levels which are different from the standard levels.

Image forming apparatus and system operable in ghost-suppression mode

An image forming apparatus includes a rotatable photosensitive member, and a charging member for electrically charging the photosensitive member in contact or proximity to the photosensitive member. The charging member forms an upstream gap and a downstream gap between the photosensitive member and itself. In addition, a power source applies a DC voltage to the charging member, an irradiation unit irradiates with light a surface of the photosensitive member in the upstream gap, and a controller controls the irradiation of the light by the irradiation unit. The photosensitive member is movable at a first speed and a second speed slower than the first speed, and wherein the irradiation of the light is effected when the photosensitive member is moved at the first speed to effect image formation, and is not effected when the photosensitive member is moved at the second speed to effect the image formation.

An image forming apparatus includes photosensitive drums; drum charging members, an AC voltage source for outputting an AC voltage commonly to at least two of the charging members; AC voltage control devices for the charging members; variable resistors connected between the AC voltage source and the at least two charging members, respectively; a use situation detecting unit for detecting use situations of the drums, respectively; and an adjusting unit for adjusting electric resistances of the variable resistors, respectively. The adjusting unit adjusts the electric resistances of the resistors in accordance with the detection results of the use situation detecting unit such that the discharge currents applied to the at least two charging members are within predetermined ranges, respectively.

Image forming apparatus using common AC voltage source for plural charging members and photosensitive members

A charging device includes a charging member to charge an image bearing member; an applying device configured to apply to the charging member a charging bias voltage comprising a DC voltage component and an AC voltage component; an AC current detector; a DC current detector; and a controller. The controller determines a saturation peak-to-peak voltage Vat which the detected DC current saturates when a peak-to-peak voltage of the AC voltage is increased, calculates a relational expression using only a detected AC current when a peak-to- peak voltage which is not more than the saturation peak-to-peak voltage Vis applied, and determines the peak-to-peak voltage of the AC voltage applied to the charging member in an image forming operation on the basis of the relational expression and a detected AC current when a peak-to-peak voltage higher than the saturation peak-to-peak voltage Vis applied.

Charging apparatus with AC and DC current detection

An image forming apparatus includes a rotatable photosensitive member, a charging member, an applying device, an irradiation device, and a controller. The charging member contacts the photosensitive member to charge the photosensitive member. The applying device applies a direct-current voltage to the charging member. The irradiation device irradiates with light an upstream charging gap located upstream of a contact portion between the photosensitive member and the charging member in a rotation direction of the photosensitive member. The controller controls the irradiation device to irradiate with a first light amount when the photosensitive member rotates at a first speed, and to irradiate with a second light amount that is larger than the first light amount when the photosensitive member rotates at a second speed that is lower than the first speed.

Image forming apparatus to control photosensitive member irradiation

An image forming apparatus includes a rotatable photosensitive member; charging device for electrically charging the photosensitive member by being supplied with a charging bias; a current detecting device for detecting a DC current flowing when a test bias in the form of a predetermined DC voltage biased with a predetermined AC voltage is applied to the charging device so as to cause discharging between the photosensitive member and the charging device; and a control device for controlling the charging bias on the basis of an output of the current detecting device.

An image forming apparatus includes a photosensitive member; a charging member contactable to said photosensitive member to electrically charge said photosensitive member; applying means applying a charging bias voltage to said charging member; detecting means detecting a current flowing between said charging member and said photosensitive member; a controller for controlling said image forming apparatus to execute an operational mode for removing an electric discharge product deposited on a surface of said photosensitive member, in the case that detecting means detects a current not lower than a predetermined value when a voltage lower than a voltage at which an electric charge starts between said photosensitive member and said charging member is applied to said charging member.

Image forming apparatus including control for removing electrical discharge product

A printerincludes a photosensitive drum, a charge rollerfor electrically charging the photosensitive drum, a developing devicefor developing an electrostatic latent image on the photosensitive druminto a toner image, a transfer rollerfor transferring the toner image onto a recording material, and a transfer residual toner charging memberfor electrically charging toner remaining on the photosensitive drum. In the printer, a DC voltage substantially identical to a potential on the photosensitive drumbefore the photosensitive drumreaches the charge rolleris applied to the charge rollertogether with application of a voltage of an identical polarity to a charge polarity of toner to the transfer residual toner charging memberduring a current measuring operation for measuring a value of AC current passing through the charge roller, in order to set a condition of a voltage to be applied to the charge rollerduring image formation, by applying an AC voltage to the charge roller

Image forming apparatus with residual toner transfer prevention feature

An image forming apparatus having an image forming device for forming an image on a recording material, a fixing member for fixing the image formed on the recording material in a fixing nip, and a pressure member brought into pressure contact with the fixing member to form the fixing nip, the hardness of the pressure member being smaller than the hardness of the fixing member, wherein the image forming apparatus is operable in a mode for inserting the recording material into the fixing nip so that the image forming surface of the recording material is brought into contact with the pressure member, and subjecting the recording material to a preheating process, and then forming the image.

Image forming apparatus with preheating mode operating before image formation

An image forming apparatus includes an image bearing member which is movable; an electrifying device which makes contact with the image bearing member and electrifies the image bearing member; a developing device for developing a latent image on the image bearing member by toner; and an abutting member which is provided on a downstream side in a moving direction of the image bearing member with respect to the electrifying device and the contacting portion of the image bearing member and abuts against the image bearing member. The image bearing member, electrified by the electrifying device, is exposed to have the latent image formed thereon, a toner image formed on the image bearing member by the developing device is transferred to a recording material, and the developing device recovers residual toner on the image bearing member after transfer.

Image forming apparatus having a member for barring an electrification particle form leaking

Toner particles fly off from a photosensitive drum to an exposure light emitting portion by a change of electric potential distribution on the photosensitive drum caused by image exposure in a following process. This causes a poor copy of an image by adhering the toner particles to the exposure light emitting portion. This phenomena affects a tandem type of copiers with multi-stations including photosensitive drums and exposure light emitting positions. An apparatus capable of suppressing toner adhesion to an exposure is provided to solve the above problem.

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Toride, Japan

Kenichi Shibuya