Abstract: A charging apparatus includes a charging member to charge a surface of a photoconductive medium, a power unit to supply an electric power as a bias voltage to the charging member, and a resistor unit to reduce a ripple on the surface of the charging member. Accordingly, a stability of the charging apparatus is secured without using a separate power device.

Abstract: A power source includes a voltage setting unit configured to set an output voltage, a voltage generation unit configured to output the set voltage to a load, a feedback unit configured to detect the output voltage and feed back the detected voltage to the voltage setting unit, a current detection unit configured to detect a current value which is a sum of a current value flowing in the feedback unit and a current value flowing in the load when the set voltage is output to the load, and a control unit configured to switch between a constant current control which controls the set voltage so that the detected current value becomes a constant current, and a constant voltage control which controls the set voltage so that the voltage output to the load becomes a constant voltage based on the voltage value that is fed back by the feedback unit.

Abstract: An image forming apparatus including an AC high voltage power supply, a DC high voltage power supply, and a high voltage power supply apparatus, which outputs an output voltage at an output end by superposing an output of the AC high voltage power supply and an output of the DC high voltage power supply. The high voltage power supply apparatus has a positive peak detector detecting a positive peak of the voltage at an output end, and a negative peak detector detecting a negative peak of the voltage at an output end. An output voltage of at least one of the AC high voltage power supply and the DC high voltage power supply is controlled on the basis of the detection result of at least one of the positive peak detector and the negative peak detector.

Abstract: An aspect of the invention provides a charging control device of a color image forming apparatus, and the charging control device can properly control a charging potential of an image bearing body such that fog and uneven density are not generated even in a low-temperature environment. The image forming apparatus includes a high-voltage generation circuit 91 which applies an oscillating voltage to the charging member 42 disposed in contact with an image bearing body 41, a direct-current voltage and an alternating-current voltage being superimposed to form the oscillating voltage; a current detection unit 92 which detects a direct current value passed from the charging member 42 to the image bearing body 41; and a voltage control unit 96 which controls the alternating-current voltage such that the detected direct-current value is maintained in a target current range. The image forming apparatus also includes an aging control unit 95 to perform running-in.

Abstract: A method of operating an electrostatographic printing apparatus, the apparatus including a charge-retentive member defining an imaging surface and a charging device for placing a charge on the imaging surface, including the steps of: providing a power supply to apply a bias to the bias charging roll; and applying a bias to the bias charging roll, the applying includes applying a burst modulated waveform to the bias charging roll.

Abstract: The size of a resonance noise due to a signal of an alternating voltage applied to a charging member (charging roller) is detected by a piezoelectric device (PZ), and in cases in which the size of the detected resonance noise (detection signal level) exceeds a predetermined size, the frequency of the alternating voltage signal applied to the charging member is shifted, by a control unit (50), by a predetermined frequency amount only.

Abstract: An image forming apparatus includes a photosensitive body to be developed by a conductive toner, a charger which charges a surface of the photosensitive body with a surface potential, a power supply which supplies one of a normal charging power to perform a normal charging operation and a compensation charging power, having a different absolute value than the normal charging power and having the same polarity as the normal charging power, to the charger, and a controller which controls the power supply to supply the normal charging power and the compensation charging power to the charger, respectively, before and after a charging time at which a rear end contact surface of the photosensitive body contacting a rear end of a printing medium is charged by the charger.

Abstract: A low-voltage power source circuit board is provided downstream in relation to the flow of air introduced through an intake hole and exhausted by a power source fan. Heat sinks are provided on the low-voltage power source circuit board on electronic parts that generate a large amount of heat, the plate surfaces of the heat sinks being arranged along the direction of airflow, thereby minimizing their resistance to the airflow. Air including heat generated from these electronic parts is exhausted by the power source fan without the air heating the high-voltage power source circuit board or engine circuit board that are disposed upstream in relation to the direction of airflow.

Abstract: An image forming apparatus includes an image forming part that forms an image on a recording medium and includes a plurality of photoconductors, a plurality of charging parts that charges the photoconductors, a plurality of developing parts that develops the charged photoconductors, and a plurality of static electricity erasing parts that erases surface potentials of the charged photoconductors. A power supplying part supplies power to the image forming part, and a controller controls to switch the operation of the static electricity erasing parts independently and controls the image forming part to form the image on the recording medium if power applied to the respective photoconductors through the charging parts and the developing parts reaches a target value.

Abstract: An output system having an output device that performs output based on output data so that the output device performs the output after having acquired authentication. In the system, an operating state controlling unit outputs a power-save-cancel command for causing a power-saving state to be changed into an active state to a power-save switching unit after a device having an output data storing unit acquires the output data, and a transition-to-power-save command for causing the state to be changed from the active state to the power-saving state is outputted to the power-save switching unit when the output process of the output data is completed by an output process completion detecting unit.

Abstract: An image forming apparatus (1) according to the present invention includes a high voltage circuit board (14) and a driving unit (10). A frame (4B) is provided in the apparatus (1) to support an image forming unit (2). The frame (4B) has a partition face (5), which defines a boundary between an inner side (D1) and an outer side (D2) and faces toward the outer side (D2). An electric discharger (7) and driving mechanisms (11, 12, 13) are provided on the inner side (D1) inward of the partition face (5). The high voltage circuit board (14) and the driving unit (10) for operating the driving mechanisms (11, 12, 13) are provided on the outer side (D2) outward of the partition face (5). The high voltage circuit board (14) is fixed directly to the partition face (5) on the outer side (D2). The driving unit (10) is fixed to the partition face (5) from the outer side (D2) so as to be located outwardly of the high voltage circuit board (14) on the outer side (D2) and overlap the high voltage circuit board (14).

Abstract: Obtained is an image generating apparatus capable of suppressing power consumption in the overall apparatus in printing. This image generating apparatus includes a driving source for driving transport means transporting a paper printable with image data and a control portion supplying a first amount of energy to the driving source in an acceleration period of the driving source for bringing the paper to a constant speed from the start of transportation while switching to a second amount of energy smaller than the first amount of energy in synchronization with arrival of the paper at the constant speed for supplying the second amount of energy to the driving source.

Abstract: A photoconductor charging system for use with an image forming device. The image forming device may include a plurality of image forming units transferring toner particles to a media substrate and each of the plurality of image forming units including a photoconductive unit and a corresponding charging unit positioned to charge the photoconductive unit. Generally, an alternating current power supply may be coupled to one or more of the charging units and supply a voltage thereto. The alternating current power supply may include a switching mode amplifier. In one embodiment, the switching mode amplifier is a class D amplifier. The charging system may further include a filter to filter an output of the switching mode amplifier. The filter may include a low pass L-C filter. The switching mode amplifier may operate a transistor output bridge between on and off states to improve amplifier efficiency.

Abstract: An electrophotographic document production device having a transformerless high voltage power supply located distal to its load and a transformer at the point of load.

Abstract: An image forming apparatus of the present invention includes a pair of support plates supporting the rotary shaft of a photoconductive drum at axially opposite ends of the drum. One of the support plates is openable away from the body of the apparatus and loaded with a contact forming member including a current feed path for feeding a current from a high-tension power supply for charging to a charge roller, a wiring forming a current return path that allows a current to flow from the photoconductive drum to the ground of the power supply, and a plurality of contacts where the wiring and drum contact each other. A current flowing through the current return path is sensed to execute feedback control to the output of the high-tension power supply.

Abstract: In order to be able to supply a rotating transfer roller in a transfer printing station of an electrophotographic printing device with a high voltage, a system and method is proposed that comprises a voltage transfer device with an elastically borne brush, a compensation device with a bushing standing under spring force, and a monitoring device with a Hall switch. For voltage transfer, the brush is pressed onto the voltage connection location of the transfer roller. For compensation of the axial play of the transfer roller, the bushing is pressed onto the bearing of the transfer roller. For monitoring as to whether a transfer roller is connected with the device, the Hall switch is used which checks whether the bushing has been moved or not.

Abstract: A charging voltage supply and a method for supplying a charging voltage are provided. The charging voltage supply generates a voltage and branches the generated voltage to at least one charging roller according to voltage applied to a transfer roller. Accordingly, the charging voltage supply can compensate for the charging voltage in view of the reduction of a charging potential of a photosensitive body according to the transfer voltage.

Abstract: An electrophotographic image forming apparatus on which a process cartridge is detachably mountable forms an image on a recording medium, and has a main body electrical contact electrically connected to a cartridge electrical contact when the cartridge is mounted on an apparatus main body, an electrically grounded electrically conductive discharge preventing member for effecting discharge between it and a charged foreign substance to thereby prevent discharge from occurring between the foreign substance and the main body electrical contact when the foreign substance has entered the apparatus main body on which the process cartridge is not mounted. The discharge preventing member is movable between a first position located in the entry route of the cartridge and a second position retracted from the first position and located outside the entry route. The apparatus also has an actuating member for moving the discharge preventing member from the first to the second position.

Abstract: An image forming apparatus comprising an image bearing member, a transfer mechanism that transfers a developer image formed on the image bearing member, a charger that charges the image bearing member, a first high voltage power supply substrate that applies a first voltage to the transfer mechanism, and a second high voltage power supply substrate that applies a second voltage to the charger, wherein the second voltage has a polarity opposite to the first voltage.

Abstract: In a sheet processing apparatus, which is connected to an image forming apparatus, applies a predetermined process to a plurality of sheets that have undergone image formation as a unit, and has power storage means capable of storing electric power required to execute the process, the output voltage from the power storage means is detected, and when the detected voltage exceeds a predetermined value, the process is controlled to execute the process using the electric power stored in the power storage means in accordance with an instruction from the image forming apparatus. Since the process is executed using the electric power supplied from the power storage means, consumption power can be prevented from temporarily increasing upon execution of the process.

Abstract: A process cartridge is detachably mountable to a main assembly of an electrophotographic image forming apparatus. The main assembly includes an output contact movable between electrical connecting and retracted positions, a displaceable member for moving the output contact, and an elastic function member for elastically urging the displaceable member to urge the output contact toward the retracted position. The cartridge includes an electrophotographic photosensitive drum, a process device actable on the drum, and a movable operation member engageable with a main-assembly fixed engageable member and with the displaceable member to move the output contact from the retracted to the electrical connecting position against the bias of the elastic function member, in interrelation with the movement of the displaceable member, after the engagement with the fixed engageable member when the cartridge is inserted into the main assembly. The cartridge also includes an input electrical contact.

Abstract: A method of operating an electrostatographic printing apparatus, the apparatus including a charge-retentive member defining an imaging surface and a charging device for placing a charge on the imaging surface, a gap existing between the imaging surface and the charging device, including applying an electrical bias to the charge-retentive member by generating a burst modulated waveform.

Abstract: An output of a DC high voltage source is supplied as a bias to a heat fixing apparatus. An output of the DC high voltage source is divided by resistors, and a divided output is supplied as a DC bias to a charging apparatus. A feedback circuit generates a feedback signal corresponding to a difference between the divided output and a reference voltage, for supply to the DC high voltage source thereby controlling the divided output voltage at a desired value. Such structure allows a supply of a bias voltage to the heat fixing apparatus higher than the bias voltage to the charging apparatus, thereby eliminating defects in the fixing apparatus such as a fixation tailing or an offset phenomenon. Also the charging apparatus can be given an exactly controlled bias voltage, thereby avoiding a halftone density unevenness resulting from an uneven charging.

Abstract: An image forming device that uses a power transformer (T) such that no action delay and performance degradation/malfunction occur even in a power save mode, thereby achieving high energy efficiency. Circuits (2, 3, 4) of the image forming device are divided into to two blocks (A, B), and the power transformer (T) has two sets of windings (TA, TB), one for one of the blocks (A) that always needs power feeding and one for the other block (B) that needs power when necessary. Switches (SW) are provided on lines (L1 to L5) extending from the latter block (B) such that these switches are opened to interrupt power supply when the device is brought into the power save mode.

Abstract: Disclosed is a printer which performs efficient power save control by keeping track of the condition of each client of the printer without having to send wasteful packets, that is, without affecting the network environment. The printer includes: a unit for monitoring packets flowing on a network, and for updating and storing a client-associated last receive time each time a packet is received from any client of the printer; a unit for determining, by referring to the stored client-associated last receive time, that any client from whose associated last receive time has elapsed a prescribed time is in an idle condition, and for computing a printer usage rate by summing the past average usage rates of the clients that have been determined not to be in an idle condition; and a unit for setting, based on the computed printer usage rate, the length of time allowed before a transition is made to the power save mode.

Abstract: An image forming device is provided that is capable of easily preventing occurrence of stripe-like image noise that may be caused by intimate contact between a contact electrifying member and an image carrier even when an image forming operation is stopped for a while. In the image forming device having an electrifying roller in contact with a photoconductor, AC voltage is applied to the electrifying roller before the image carrier and the electrifying roller start rotating.

Abstract: An image forming apparatus includes a control voltage generation circuit which inputs a primary AC voltage to the primary side of a voltage transformer, generates a control voltage corresponding to a current generated on the secondary side of the voltage transformer in accordance with the primary AC voltage, and controls the primary AC voltage on the basis of the control voltage and a control signal, a current detection circuit which is connected, through a capacitor, to a path which supplies the current generated on the secondary side of the voltage transformer to a charge roller and detects a charge current to charge an image carrier, and a control circuit which determines the control signal on the basis of the relationship between a predetermined control signal (PRICNT) and a current value (Icap) detected by the current detection circuit in accordance with the predetermined control signal and controls the primary AC voltage to be generated by the voltage generation circuit.

Abstract: A process cartridge is detachably mountable to a main assembly of an electrophotographic image forming apparatus. The main assembly includes an output contact movable between electrical connecting and retracted positions, a displaceable member for moving the output contact, and an elastic function member for elastically urging the displaceable member to urge the output contact toward the retracted position. The cartridge includes an electrophotographic photosensitive drum, a process device actable on the drum, and a movable operation member engageable with a main-assembly fixed engageable member and with the displaceable member to move the output contact from the retracted to the electrical connecting position against the bias of the elastic function member, in interrelation with the movement of the displaceable member, after the engagement with the fixed engageable member when the cartridge is inserted into the main assembly. The cartridge also includes an input electrical contact.

Abstract: A color image forming apparatus which, in a sequential order for each of plural colors of a composite color image, charges plural photosensitive bodies, exposes electrostatic latent images on the plural photosensitive bodies, develops latent images on the photosensitive bodies into color images, and transfers the color images to sequentially form images of each of the plural colors one on another to form the composite color image and transcribing the composite color image onto a printing medium. The color image forming apparatus includes: plural charging units which perform the charging process for each of the plural colors; plural exposing units which perform the exposing process for each of the plural colors; plural developing units which perform the developing process for each of the plural colors; and plural transfer units which perform the transfer process for each of the plural colors.

Abstract: A method of operating an electrostatographic printing apparatus, the apparatus including a charge-retentive member defining an imaging surface and a charging device for placing a charge on the imaging surface, including the steps of: providing a power supply to apply a bias to the bias charging roll; and applying a bias to the bias charging roll, the applying includes applying a burst modulated waveform to the bias charging roll.

Abstract: An electrophotographic image-forming apparatus and a charging voltage control method therefor. The electrophotographic image-forming apparatus has a charging roller applying a predetermined voltage to a photosensitive medium, a developing roller for developing with a developing agent an electrostatic latent image formed on the photosensitive medium by a laser scanning unit, a transfer roller transferring onto a sheet of recording paper the image developed by the developing agent, and a high voltage power supply (HVPS) applying predefined voltages to the respective rollers.

Abstract: The present invention is a charging device that electrically charges an object that is charged while being moved in a predetermined direction and an image forming device having such a charging device. The charging device has: a charging member that electrically charges the charged object; a power source that supplies electric power to the charging member in order to electrically charge the charged object; a contact member arranged downstream relative to the charging member as viewed in the moving direction of the charged object and adapted to contact the charged object directly or by way of a predetermined intermediary medium; an ammeter that gauges an electric current caused to flow through the contact member due to an electric charge on the charged object electrically charged by the charging member; and a power source control section that controls the power source based on the electric current gauged by the ammeter.

Abstract: The present invention relates to an electric contact member applying a voltage from a voltage applying device to a charger reciprocally moving in a longitudinal direction of an image carrier. The member includes a securing portion electrically connected to a side of the voltage applying device, a moving portion reciprocally movable and connected electrically to a side of the charger, and a buffer portion formed between the securing portion and the moving portion.

Abstract: An electrophotographic image forming apparatus having a photosensitive member 1, a charging roller 2 and a developing roller 31, and including an output variable power source 8 common to the charging and the developing rollers 2 and 31 for applying voltages to the charging and developing rollers 2 and 31, respectively, a power source output control portion 9, and a voltage changing device (Zener diode D1) interposed between the developing roller 31 and the power source 8, wherein, when the voltages applied to the charging and developing rollers 2 and 31 are raised to and lowered from voltages required for image formation, respectively, the control portion 9 controls an output of the power source 8 to perform the raising and lowering of the applied voltages for a predetermined time while keeping a potential difference for suppressing movement of developer onto the photosensitive member 1 between the voltages applied to the charging and developing rollers 2 and 31.

Abstract: A method of controlling a charging potential of an organic photoconductive cell (OPC) includes a first operation of applying two charging voltages Vc1 and Vc2 having respective duties D1 and D2 established in an engine controller unit (ECU) to a conductive roller via a high voltage power supply (HVPS) to charge the OPC, a second operation of measuring sensing voltages Vs1 and Vs2 through a sensing resistor Rs coupled to the conductive roller so that the ECU establishes a target charging current it and calculates a new charging voltage Vc3 and a new duty D3, a third operation of applying the new charging voltage Vc3 and the new duty D3 to the conductive roller via the HVPS to charge the OPC and measuring a charging current Ic3 of the conductive roller, and a fourth operation of comparing a difference between the charging current Ic3 of the conductive roller and the target charging current It with a tolerance value TOL to control the charging potential by using the target charging current when the difference is

Abstract: An apparatus for applying an electrical charge to a charge retentive surface, wherein a bias charge roll member is situated proximately to a surface to be charged such as, a photoreceptor. The bias contact roll member is supplied with an electrical bias including an oscillating voltage signal having, in one mode of operation, a clipped AC input voltage and in a second mode, an unclipped AC input voltage.

Abstract: The present invention is a charging device that electrically charges an object that is charged while being moved in a predetermined direction and an image forming device having such a charging device. The charging device has: a charging member that electrically charges the charged object; a power source that supplies electric power to the charging member in order to electrically charge the charged object; a contact member arranged downstream relative to the charging member as viewed in the moving direction of the charged object and adapted to contact the charged object directly or by way of a predetermined intermediary medium; an ammeter that gauges an electric current caused to flow through the contact member due to an electric charge on the charged object electrically charged by the charging member; and a power source control section that controls the power source based on the electric current gauged by the ammeter.

Abstract: An apparatus and process for applying an electrical charge to a photoreceptor wherein a bias charge roll member is situated in contact or in close proximity with a surface of a member to be charged such as a photoreceptor. The bias charge roll member is supplied with an electrical bias having a variable voltage waveform onto which a DC bias is superimposed. The amount of DC bias is selected to set the signal voltage such that a minimally acceptable amount of AC corona is created sufficient for uniform photoreceptor charging while avoiding unnecessary excessive positive corona that causes excessive photoreceptor wear.

Abstract: An apparatus and process for applying an electrical charge to a photoreceptor wherein a bias charge roll member is situated in contact or in close proximity with a surface of member to be charged such as a photoreceptor. The bias charge roll member is supplied with an electrical bias having a rectified AC waveform onto which a DC bias is superimposed after the waveform has been rectified. The result is the ability to raise the voltage potential of the photoreceptor with less pulse voltage and, more particularly, to increase the voltage potential of the photoreceptor along as if only DC voltage were applied far above what is possible in the prior art. Among the advantages of the invention is the ability to minimize photoreceptor wear at higher levels of photoreceptor charge since the DC-offset bias enables the second Paschen threshold to be avoided for higher levels of the photoreceptor charge.

Abstract: An apparatus and process for applying an electrical charge to a photoreceptor wherein a bias charge roll member is situated in contact or in close proximity with a surface of member to be charged such as a photoreceptor. The bias charge roll member is supplied with an electrical bias having a rectified AC waveform onto which a DC bias is superimposed after the waveform has been rectified. The result is the ability to raise the voltage potential of the photoreceptor with less pulse voltage and, more particularly, to increase the voltage potential of the photoreceptor along as if only DC voltage were applied far above what is possible in the prior art. Among the advantages of the invention is the ability to minimize photoreceptor wear at higher levels of photoreceptor charge since the DC-offset bias enables the second Paschen threshold to be avoided for higher levels of the photoreceptor charge.

Abstract: An apparatus for applying an electrical charge to a charge retentive surface, wherein a bias charge roll member is situated proximately to a surface to be charged such as, a photoreceptor. The bias contact roll member is supplied with an electrical bias including an oscillating voltage signal having, in one mode of operation, a clipped AC input voltage and in a second mode, an unclipped AC input voltage.

Abstract: An apparatus and process for applying an electrical charge to a photoreceptor wherein a bias charge roll member is situated in contact or in close proximity with a surface of a member to be charged such as a photoreceptor. The bias charge roll member is supplied with an electrical bias having a variable voltage waveform onto which a DC bias is superimposed. The amount of DC bias is selected to set the signal voltage such that a minimally acceptable amount of AC corona is created sufficient for uniform photoreceptor charging while avoiding unnecessary excessive positive corona that causes excessive photoreceptor wear.

Abstract: An electrophotographic image forming apparatus having a photosensitive member 1, a charging roller 2 and a developing roller 31, and including an output variable power source 8 common to the charging and the developing rollers 2 and 31 for applying voltages to the charging and developing rollers 2 and 31, respectively, a power source output control portion 9, and a voltage changing device (Zener diode D1) interposed between the developing roller 31 and the power source 8, wherein, when the voltages applied to the charging and developing rollers 2 and 31 are raised to and lowered from voltages required for image formation, respectively, the control portion 9 controls an output of the power source 8 to perform the raising and lowering of the applied voltages for a predetermined time while keeping a potential difference for suppressing movement of developer onto the photosensitive member 1 between the voltages applied to the charging and developing rollers 2 and 31.

Abstract: A method of controlling a charging potential of an organic photoconductive cell (OPC) includes a first operation of applying two charging voltages Vc1 and Vc2 having respective duties D1 and D2 established in an engine controller unit (ECU) to a conductive roller via a high voltage power supply (HVPS) to charge the OPC, a second operation of measuring sensing voltages Vs1 and Vs2 through a sensing resistor Rs coupled to the conductive roller so that the ECU establishes a target charging current It and calculates a new charging voltage Vc3 and a new duty D3, a third operation of applying the new charging voltage Vc3 and the new duty D3 to the conductive roller via the HVPS to charge the OPC and measuring a charging current Ic3 of the conductive roller, and a fourth operation of comparing a difference between the charging current Ic3 of the conductive roller and the target charging current It with a tolerance value TOL to control the charging potential by using the target charging current when the difference is

Abstract: A combined charge/recharge xerographic power supply is provided that utilizes one power supply to drive the charge pin scorotron and recharge discorotron grids of a electrophotographic or xerographic system. The power supply uses recycled power from the pin scorotron grid to drive the discorotron grid. In particular, the power supply uses power that is dissipated in the traditional shunt regulator attached to the pin scorotron grid terminal to drive and provide active current to the discorotron grid through a series-pass regulation circuit. Thereby providing reduced electromagnetic emissions and reduced unit manufacturing costs.

Abstract: A combined charge/recharge xerographic power supply is provided that utilizes one power supply to drive the charge pin scorotron and recharge discorotron grids of a electrophotographic or xerographic system. The power supply uses recycled power from the pin scorotron grid to drive the discorotron grid. In particular, the power supply uses power that is dissipated in the traditional shunt regulator attached to the pin scorotron grid terminal to drive and provide active current to the discorotron grid through a series-pass regulation circuit. Thereby providing reduced electromagnetic emissions and reduced unit manufacturing costs.

Abstract: An image forming apparatus includes an image bearing member; an electrostatic image forming unit for forming an electrostatic image on said image bearing member, the electrostatic image forming unit including a flexible charge member for electrically charging the image bearing member, the charge member forming a nip between the image bearing member and itself and is supplied with an oscillating voltage, wherein electroconductive particles are provided in the nip; and a developing unit for developing an electrostatic image formed on the image bearing member with a developer, the developing unit being capable of a residual developer on the image bearing member, wherein a frequency f (cycle/sec) of the oscillating voltage and a peripheral speed v (mm/sec) of the image bearing member satisfy |f/v|≧12 (cycle/mm).

Abstract: A process cartridge detachably mountable to a main body of an image forming apparatus, includes an image bearing member, a charging member for charging the image bearing member while the charging member is in contact with the image bearing member, and a storage device for storing information concerning the type of the charging member.

Abstract: In a structure including a voltage control circuit 1 for changing a voltage control signal 14 to control an oscillation amplitude of a transistor Q1 for oscillation, thereby stabilizing a voltage of a secondary output 13, there are provided a load suppressing circuit 5 for restricting a lower limit of a load impedance of a secondary coil L2 to prevent the oscillation of the transistor Q1 for oscillation from being stopped when the secondary output 13 is short-circuited, and an intermittent control circuit 2 for repeating an operation for reducing a voltage of the voltage control signal 14 to stop the oscillation when detecting a short circuit of a load and for raising the voltage of the voltage control signal 14 to restart the oscillation after stopping the oscillation.

Abstract: A charging device comprises a conductor, which is in contact with a photoconductor, and a power source circuit, which applies a voltage to the conductor and electrically charges the photoconductor as to have a predetermined level of potential. The power source circuit includes a resistor having a predetermined level of resistance, and provides the conductor with a voltage through the resistor, thereby to stabilize the charged potential of the photoconductor.