Abstract: An AC measuring circuit measures a magnitude of an alternating current flowing through a bias applying circuit synchronized with a cycle of an AC voltage in a developing bias voltage. A control unit changes a level of the AC voltage in the developing bias voltage, and executes a developing bias adjustment process for setting a level of the AC voltage based on the level of the AC voltage when the leakage current detecting circuit detects the direct current. The control unit, when a measurement by the AC measuring circuit during execution of a developing process exceeds a predetermined allowable value, executes a warning process to prompt execution of the developing bias adjustment process, or the control unit executes the developing bias adjustment process to update the level of the AC voltage.

Abstract: An exposure device irradiates a light beam to the photoconductor drum and thereby forms an electrostatic latent image on a photoconductor drum. A developing roller causes toner to adhere to the electrostatic latent image and thereby develops a toner image. A development bias power supply circuit applies a development bias to the developing roller. A direct current detection circuit detects a direct current that flows between the development bias power supply circuit and the developing roller. A control circuit (a) causes the exposure device to form an electrostatic latent image of an adjustment patch for toner density adjustment, (b) measures a value of the direct current at a timing when the developing roller causes the toner to adhere to the electrostatic latent image of the adjustment patch, and (c) performs the toner density adjustment on the basis of the measured value of the direct current.

Abstract: An AC measuring circuit measures a magnitude of an alternating current flowing through a bias applying circuit synchronized with a cycle of an AC voltage in a developing bias voltage. A control unit changes a level of the AC voltage in the developing bias voltage, and executes a developing bias adjustment process for setting a level of the AC voltage based on the level of the AC voltage when the leakage current detecting circuit detects the direct current. The control unit, when a measurement by the AC measuring circuit during execution of a developing process exceeds a predetermined allowable value, executes a warning process to prompt execution of the developing bias adjustment process, or the control unit executes the developing bias adjustment process to update the level of the AC voltage.

Abstract: A controller (a) increases a development bias when a surface potential of the photoconductor drum is 0 Volt, and determines a level of the development bias as a discharge voltage at a timing when discharge is detected between a photoconductor drum and a developing roller, (b) sets an alternating current component of the development bias so as to make a lowest level of the development bias equal to a level lower by the discharge voltage than a desired surface potential of the photoconductor drum, and (c) increases an applied voltage to a charging roller (that charges a surface of the photoconductor drum) when applying to the developing roller the development bias of which the alternating current component has been set, and determines as an applied voltage to the charging roller corresponding to the desired surface potential, the applied voltage at a timing when the discharge is detected.

Abstract: Provided is an electronic apparatus that can prevent erroneous detection of a sensor output due to an AC line noise. A power supply circuit includes a noise filter, input rectifying smoothing circuit, converter circuit, and output smoothing circuit. The input rectifying smoothing circuit rectifies an input AC voltage passed through the noise filter to a pulsating flow and then smooth it. The converter circuit converts a DC voltage rectified and smoothed into a desired output voltage. The output smoothing circuit smoothes the convert output voltage to supply it to a control part. The noise determination part detects a noise that could not have been removed by the noise filter, as an AC line noise. The control part invalidates a detection signal outputted from the sensor for a previously set invalid period from the moment the AC line noise has been detected.

Abstract: An exposure device irradiates a light beam to the photoconductor drum and thereby forms an electrostatic latent image on a photoconductor drum. A developing roller causes toner to adhere to the electrostatic latent image and thereby develops a toner image. A development bias power supply circuit applies a development bias to the developing roller. A direct current detection circuit detects a direct current that flows between the development bias power supply circuit and the developing roller. A control circuit (a) causes the exposure device to form an electrostatic latent image of an adjustment patch for toner density adjustment, (b) measures a value of the direct current at a timing when the developing roller causes the toner to adhere to the electrostatic latent image of the adjustment patch, and (c) performs the toner density adjustment on the basis of the measured value of the direct current.

Abstract: A controller (a) increases a development bias when a surface potential of the photoconductor drum is 0 Volt, and determines a level of the development bias as a discharge voltage at a timing when discharge is detected between a photoconductor drum and a developing roller, (b) sets an alternating current component of the development bias so as to make a lowest level of the development bias equal to a level lower by the discharge voltage than a desired surface potential of the photoconductor drum, and (c) increases an applied voltage to a charging roller (that charges a surface of the photoconductor drum) when applying to the developing roller the development bias of which the alternating current component has been set, and determines as an applied voltage to the charging roller corresponding to the desired surface potential, the applied voltage at a timing when the discharge is detected.

Abstract: An image forming apparatus includes a first roller, a second roller, a first voltage applying section, and a control section. An electrostatic latent image is formed on the first roller. The second roller is located opposite to the first roller with a first gap therebetween. The first voltage applying section applies voltage to the second roller. The control section determines a first voltage value to be applied to the second roller during development of the electrostatic latent image. The control section determines a first distance non-uniformity value indicating a degree of non-uniformity of a distance across the first gap. The control section determines a first indicator value by increasing voltage applied to the second roller in stages and performing electrical discharge measurement at each of the stages. The control section determines the first voltage value based on the first distance non-uniformity value and the first indicator value.

Abstract: An image forming apparatus includes an alternating transformer that splits an alternating voltage into a first alternating voltage and a second alternating voltage, a developer bias application unit, an alternating voltage shutoff unit, and a discharge starting voltage measurement unit. The developer bias application unit applies a pulsed sleeve roller voltage composed of a first alternating voltage superimposed on a first direct voltage to a sleeve roller and also applies a second alternating voltage and a second direct voltage separately to a magnetic roller in order to apply a pulsed magnetic roller voltage composed of the second alternating voltage superimposed on the second direct voltage. The alternating voltage shutoff unit stops applying the second alternating voltage to the magnetic roller. The discharge starting voltage measurement unit increases the alternating voltage of the alternating transformer to measure the discharge starting voltage between the sleeve roller and magnetic roller.

Abstract: An image forming apparatus includes a first roller, a second roller, a first voltage applying section, and a control section. An electrostatic latent image is formed on the first roller. The second roller is located opposite to the first roller with a first gap therebetween. The first voltage applying section applies voltage to the second roller. The control section determines a first voltage value to be applied to the second roller during development of the electrostatic latent image. The control section determines a first distance non-uniformity value indicating a degree of non-uniformity of a distance across the first gap. The control section determines a first indicator value by increasing voltage applied to the second roller in stages and performing electrical discharge measurement at each of the stages. The control section determines the first voltage value based on the first distance non-uniformity value and the first indicator value.

Abstract: An image forming apparatus includes an alternating transformer that splits an alternating voltage into a first alternating voltage and a second alternating voltage, a developer bias application unit, an alternating voltage shutoff unit, and a discharge starting voltage measurement unit. The developer bias application unit applies a pulsed sleeve roller voltage composed of a first alternating voltage superimposed on a first direct voltage to a sleeve roller and also applies a second alternating voltage and a second direct voltage separately to a magnetic roller in order to apply a pulsed magnetic roller voltage composed of the second alternating voltage superimposed on the second direct voltage. The alternating voltage shutoff unit stops applying the second alternating voltage to the magnetic roller. The discharge starting voltage measurement unit increases the alternating voltage of the alternating transformer to measure the discharge starting voltage between the sleeve roller and magnetic roller.

Abstract: Provided is an electronic apparatus that can prevent erroneous detection of a sensor output due to an AC line noise. A power supply circuit includes a noise filter, input rectifying smoothing circuit, converter circuit, and output smoothing circuit. The input rectifying smoothing circuit rectifies an input AC voltage passed through the noise filter to a pulsating flow and then smooth it. The converter circuit converts a DC voltage rectified and smoothed into a desired output voltage. The output smoothing circuit smoothes the convert output voltage to supply it to a control part. The noise determination part detects a noise that could not have been removed by the noise filter, as an AC line noise. The control part invalidates a detection signal outputted from the sensor for a previously set invalid period from the moment the AC line noise has been detected.

Abstract: A developing device includes a developing roller, a magnetic roller opposed to the developing roller so as to form a magnetic brush, a high voltage power supply including a transformer having secondary side outputs one of which is connected to the developing roller while the other output is connected to the magnetic roller, so as to apply AC voltages to the developing roller and the magnetic roller, a detection portion for detecting occurrence of discharge between the developing roller and the photoreceptor drum, a restriction portion for restricting movement of toner from the magnetic roller to the developing roller, and a moving portion configured to move the restriction portion in discharge start voltage detection mode so as to restrict toner movement to the developing roller.

Abstract: A developing device includes a developing roller, a magnetic roller, a capacitor, a transformer, and a control signal generating unit. The developing roller carries toner. The magnetic roller performs supply of toner to the developing roller and removal of toner from the developing roller. The transformer includes a primary side to which a capacitor is connected and a secondary side from which an AC voltage is output and applied to the developing roller. The control signal generating unit inputs a control signal to the capacitor and adjusts a DC bias value of the control signal so that a DC component of the control signal is the same before and after the change of the duty ratio of the control signal.

Abstract: A developing device includes a developing roller, a magnetic roller, a capacitor, a transformer, and a switching portion. The magnetic roller supplies toner to the developing roller or takes off the toner from the same. The capacitor is connected to a primary of the transformer, and the developing roller is connected to a secondary of the same. During a period while the voltage between electrodes of the capacitor is changing, the switching portion changes the duty ratio in a predetermined second time slot in which current flowing in the switching portion is smaller than that flowing in a first time slot.

Abstract: A developing device includes a developing roller, a magnetic roller opposed to the developing roller so as to form a magnetic blush, a high voltage power supply including a transformer having secondary side outputs one of which is connected to the developing roller while the other output is connected to the magnetic roller, so as to apply AC voltages to the developing roller and the magnetic roller, a detection portion for detecting occurrence of discharge between the developing roller and the photoreceptor drum, a restriction portion for restricting movement of toner from the magnetic roller to the developing roller, and a moving portion configured to move the restriction portion in discharge start voltage detection mode so as to restrict toner movement to the developing roller.

Abstract: A developing device includes a development roller, a magnetic roller, a transformer, a switching portion, output control portion and a capacitor. The development roller is opposite a photoconductor drum. The magnetic roller performs, with a magnetic brush, the supply of a toner to the development roller and the removal of the toner. The transformer generates an alternating-current voltage applied to the development roller. The switching portion passes and interrupts a current to the transformer. The output control portion stepwise changes, when a duty ratio in switching is changed, the duty ratio a plurality of times from a first duty ratio to a second duty ratio. The capacitor has one end connected to the transformer and the other end connected to the switching portion.

Abstract: A developing device includes a developing roller, a magnetic roller, a capacitor, a transformer, and a control signal generating unit. The developing roller carries toner. The magnetic roller performs supply of toner to the developing roller and removal of toner from the developing roller. The transformer includes a primary side to which a capacitor is connected and a secondary side from which an AC voltage is output and applied to the developing roller. The control signal generating unit inputs a control signal to the capacitor and adjusts a DC bias value of the control signal so that a DC component of the control signal is the same before and after the change of the duty ratio of the control signal.

Abstract: An image forming apparatus has: a photoconductive drum that rotates; a developing roller that carries toner to be charged and to which a first voltage application portion outputting an AC voltage is connected; a contact member that makes contact with the photoconductive drum to remove residual toner; a detection portion for detecting occurrence of electric discharge between the developing roller and the photoconductive drum; and a developing unit that feeds toner to the developing roller, that supports the developing roller opposite the photoconductive drum with a gap secured in between, and that feeds toner to the developing roller with prescribed timing and for a prescribed time during electric discharge detection.

Abstract: A meandering detection device capable of detecting meandering of a subject with high accuracy includes: a contact which has an open end making contact with and following a subject body and which is supported by a support part; a reflection part integrally provided to the contact and reflecting light; an emission part emitting light toward the reflection part; and a first and a second light receiving parts which are disposed in front of the reflection part, which receive the light reflected by the reflection part and then outputs signals in accordance with respective amounts of light received, and which detect meandering of the subject based on a difference in the amount of light received.