Abstract: An image forming apparatus includes an image bearing member, a transfer unit, a control circuit board, and a power supply module detachably attachable relative to the image forming apparatus. The image bearing member bears a toner image on a surface thereof. The transfer unit includes a transfer device to transfer the toner image onto a recording medium and is disposed opposite the image bearing member. The control circuit board controls the transfer unit. The power supply module is disposed in the transfer unit and includes a power source to apply, between the image bearing member and the transfer device, an AC-DC superimposed bias in which an alternating voltage (AC) is superimposed on a direct current (DC) voltage to form a transfer electric field to transfer the toner image from the image bearing member onto the recording medium.

Abstract: According to an aspect of the present invention, a power supply device includes: a DC power supply that outputs a DC voltage; an AC power supply that outputs any one of the DC voltage and a superimposed voltage being the DC voltage with an AC voltage superimposed thereon; and a bypass capacitor that charges a part of a voltage that is output from the AC power supply. The DC power supply starts outputting the DC voltage in a constant voltage mode and, when a predetermined condition is satisfied, switches from the constant voltage mode to a constant current mode to output the DC voltage in the constant current mode.

Abstract: An image transfer device includes an image bearing member, a pair of opposed transfer members, a media separator, and an electrical bias applicator. The image bearing member defines an image bearing surface on which a toner image is created. The pair of opposed transfer members is disposed opposite each other via the image bearing member to form a transfer nip therebetween through which a recording medium is passed. One of the transfer members defines a first electrode to which a first electrical bias is applied. The media separator defines a second electrode downstream from the transfer nip to which a second electrical bias is applied. The electrical bias applicator includes a power supply connectable with each of the first and second electrodes to supply the first electrical bias to the first electrode and the second electrical bias to the second electrode.

Abstract: Described herein is a transfer device that transfers a visualized image formed on an image carrier onto a recording medium. The transfer device includes an image carrier that carries a toner image, a contacting member that contacts the image carrier via a recording medium and a power source that outputs a transfer bias to transfer the toner image from the image carrier onto the recording medium at a transfer nip formed between the image carrier and the contacting member. The transfer bias has a direct current component and an alternating current (AC) component superimposed on the direct current component. The transfer device also includes a controller that controls the power source such that the controller controls a level of the direct current component output from the power source by a constant current control.

Abstract: An image forming apparatus includes a transfer unit configured to transfer a toner image onto a recording medium; a power supply unit configured to output one of an alternating-current-based voltage including at least an alternating-current voltage and a direct-current voltage to the transfer unit; and a power supply control unit configured to cause the power supply unit to start switching to the alternating-current-based voltage a first time after the power supply unit stops outputting the direct-current voltage in the case that output of the power supply unit is switched to the alternating-current-based voltage, and cause the power supply unit to start switching to the direct-current voltage a second time after the power supply unit stops outputting the alternating-current-based voltage in the case that output of the power supply unit is switched to the direct-current voltage. The second time is longer than the first time.

Abstract: An image forming apparatus includes a calculating unit configured to specify pieces of thickness information for calculation of a difference between thicknesses of a recording medium among pieces of thickness information each indicating thicknesses of the recording medium and calculate the difference using the specified pieces of thickness information, the pieces of thickness information being obtained as a detection result by sequentially detecting the thicknesses of the recording medium being conveyed; a determining unit configured to determine whether the calculated difference is equal to or larger than a first threshold; and a transfer unit configured to transfer an image onto the recording medium using at least an alternating-current voltage when the difference is equal to or larger than the first threshold.

Abstract: An image forming apparatus includes an image bearing member, an image forming unit for forming a toner image and a toner pattern comprising toner not to be transferred onto a recording medium for adjustment of a density of toner on a surface of the image bearing member, a nip forming member contacting the surface of the image bearing member to form a transfer nip therebetween, a transfer bias applicator for applying a transfer bias in which an alternating current component and a direct current component are superimposed to transfer the toner image onto the recording medium in the transfer nip, a first cleaning device to mechanically remove toner remaining on the image bearing member after passing through the transfer nip. The transfer bias applicator applies a charge eliminating bias to remove charge from toner in the toner pattern when the toner pattern passes through the transfer nip.

Abstract: A reception unit sequentially receives input of voltage values indicating an AC input voltage from an AC power supply. A ROM stores a power control table in which a power control parameter corresponding to the AC power supply voltage is matched with each group of the voltage values indicating the same AC power supply voltage. A decision unit determines to which group the received voltage values belong among the plurality of groups, whenever the reception unit receives the input of the voltage value and decides the group, to which a predetermined number of voltage values belongs among the plurality of voltage values sequentially received by the reception unit, among the plurality of groups using the determination result. A power control unit controls power supply according to the power control parameter matched with the decided group.

Abstract: An image forming apparatus includes an image bearing member, an image forming unit for forming a toner image and a toner pattern comprising toner not to be transferred onto a recording medium for adjustment of a density of toner on a surface of the image bearing member, a nip forming member contacting the surface of the image bearing member to form a transfer nip therebetween, a transfer bias applicator for applying a transfer bias in which an alternating current component and a direct current component are superimposed to transfer the toner image onto the recording medium in the transfer nip, a first cleaning device to mechanically remove toner remaining on the image bearing member after passing through the transfer nip. The transfer bias applicator applies a charge eliminating bias to remove charge from toner in the toner pattern when the toner pattern passes through the transfer nip.

Abstract: A transfer device includes a power supply control unit, a direct-current (DC) power supply, an alternating-current (AC) power supply, and a transfer unit. The power supply control unit controls a first control signal for controlling a DC voltage and a second control signal for controlling an AC voltage based on a condition relating to image formation. The DC power supply outputs the DC voltage based on the first control signal. The AC power supply selectively outputs, with a particular waveform, either of the DC voltage output from the DC power supply or a superimposed voltage obtained by superimposing the AC voltage determined based on the second control signal on the DC voltage output from the DC power supply. The transfer unit transfers a developer onto a sheet using a voltage output from the AC power supply.

Abstract: A transfer device includes a direct-current (DC) power supply configured to output a DC voltage; an alternating-current (AC) power supply configured to selectively output a superimposed voltage in which an AC voltage is superimposed on the DC voltage output from the DC power supply or the DC voltage output from the DC power supply; and a transfer unit configured to transfer a developer to a sheet using the voltage output from the AC power supply.

Abstract: An image forming apparatus includes a controller and a transfer device including a power source to output a superimposed bias in which an AC voltage is superimposed on a DC voltage, a first electrode, a second electrode disposed opposite the first electrode with an image bearing member interposed therebetween to form a transfer electric field to transfer a toner image on the image bearing member to a recording medium. The controller including a CPU adjusts the transfer electric field and a transfer speed. One of the first electrode and the second electrode is connected to the power source, and the other is grounded. The controller adjusts the transfer speed such that in a case in which an oscillating electric field of the transfer electric field is strong, a maximum transfer speed is slower than the maximum transfer speed in a case in which the oscillating electric field is weak.

Abstract: An image transfer device includes an image bearing member, a pair of opposed transfer members, a media separator, and an electrical bias applicator. The image bearing member defines an image bearing surface on which a toner image is created. The pair of opposed transfer members is disposed opposite each other via the image bearing member to form a transfer nip therebetween through which a recording medium is passed. One of the transfer members defines a first electrode to which a first electrical bias is applied. The media separator defines a second electrode downstream from the transfer nip to which a second electrical bias is applied. The electrical bias applicator includes a power supply connectable with each of the first and second electrodes to supply the first electrical bias to the first electrode and the second electrical bias to the second electrode.

Abstract: An image forming apparatus includes an image bearing member, a transfer unit, a control circuit board, and a power supply module detachably attachable relative to the image forming apparatus. The image bearing member bears a toner image on a surface thereof. The transfer unit includes a transfer device to transfer the toner image onto a recording medium and is disposed opposite the image bearing member. The control circuit board controls the transfer unit. The power supply module is disposed in the transfer unit and includes a power source to apply, between the image bearing member and the transfer device, an AC-DC superimposed bias in which an alternating voltage (AC) is superimposed on a direct current (DC) voltage to form a transfer electric field to transfer the toner image from the image bearing member onto the recording medium.

Abstract: A transfer device including an image carrier; a transfer member disposed facing the image carrier; a transfer electrical field generator including a direct-current (DC) power source to generate a DC voltage and an alternating current (AC) power source to generate an AC voltage; and a controller. The transfer electrical field generator forms the transfer electrical field between the image carrier and the transfer member using the DC voltage and the AC voltage, to transfer the toner image on the image carrier, charged to a predetermined polarity, onto the recording medium. The controller controls the AC voltage source so that, the AC voltage output from the AC voltage source when a leading edge of the recording medium is positioned in the transfer electrical field is set larger than the AC voltage when the portion of the recording medium other than the leading edge is positioned in the transfer electrical field.

Abstract: An image forming apparatus includes a transfer device to transfer a toner image from an image bearing member onto a recording medium, disposed opposite the image bearing member, a transfer bias power source to apply, between the image bearing member and the transfer device, a superimposed transfer bias in which a direct current (DC) component and an alternative current (AC) component are superimposed to transfer the toner image borne on the image bearing member to the recording medium, and a controller to change the superimposed bias that the transfer bias power source applies. The controller changes the levels of the DC component and the AC component of the superimposed transfer bias in a color mode from that in a monochrome mode to secure a return electric field in the superimposed transfer bias by which the toner is returned from the recording medium to the image bearing member.

Abstract: An image forming apparatus includes a transfer unit configured to transfer a toner image onto a recording medium; a power supply unit configured to output one of an alternating-current-based voltage including at least an alternating-current voltage and a direct-current voltage to the transfer unit; and a power supply control unit configured to cause the power supply unit to start switching to the alternating-current-based voltage a first time after the power supply unit stops outputting the direct-current voltage in the case that output of the power supply unit is switched to the alternating-current-based voltage, and cause the power supply unit to start switching to the direct-current voltage a second time after the power supply unit stops outputting the alternating-current-based voltage in the case that output of the power supply unit is switched to the direct-current voltage. The second time is longer than the first time.

Abstract: An image forming apparatus includes a transfer unit configured to transfer a toner image onto a recording medium; a power supply unit configured to apply one of a superimposed voltage in which an alternating-current voltage and a first direct-current voltage are superimposed and a second direct-current voltage to the transfer unit; and a power supply control configured to, when the power supply unit outputs the superimposed voltage, instruct the power supply unit to output the first direct-current voltage at a first timing, and, when the power-supply unit outputs the second direct-current voltage, instruct the power-supply unit to output the second direct-current voltage at a second timing which is later than the first timing.

Abstract: An image forming apparatus includes an image bearing member to bear a toner image on a surface thereof, a transfer unit including a transfer device to transfer the toner image onto a recording medium, disposed opposite the image bearing member, a direct current (DC) power source to apply, between the image bearing member and the transfer device, a DC bias to form a first transfer electric field to transfer the toner image onto the recording medium, and a power supply module detachably attachable relative to the image forming apparatus. The power supply module includes an AC-DC superimposed bias power source to apply, between the image bearing member and the transfer device, a superimposed bias in which an alternating voltage is superimposed on a DC voltage to form a second transfer electric field to transfer the toner image onto the recording medium.

Abstract: An image forming apparatus includes an image carrier; a facing member facing the image carrier via a transfer position; a power supply to output a voltage between a first position on the image carrier side and a second position on the facing member side; a resistance detector to detect electrical resistance between the first position and the second position via the transfer position; and a controller to switch between a first transfer mode in which the power supply outputs a direct current voltage, and a second transfer mode in which the power supply outputs a superimposed voltage. When a toner image on the image carrier is transferred onto a recording medium at the transfer position, the controller selects either the first transfer mode or the second transfer mode. When the resistance detector detects the electrical resistance, the controller selects the first transfer mode.