Abstract: A control circuit of an image forming apparatus outputs a pulse signal. A clock signal generation circuit generates a clock signal, based on the pulse signal. A pulse signal conversion circuit generates a pulse conversion control signal of a voltage value associated with a duty ratio of the pulse signal. An AC voltage generation circuit generates an AC voltage of a frequency based on the clock signal. Either the AC voltage generation circuit or a DC voltage generation circuit generates a voltage whose amplitude or voltage value increases as a voltage value of the received pulse conversion control signal increases, and whose amplitude or voltage value decreases as a voltage value of the pulse conversion control signal decreases.

Abstract: A resonance circuit (2) includes a capacitor (C1) and an inductor (L1, L2) of which an inductance is changed depending on developer including toner, and generates an output voltage corresponding to the inductance. A detecting circuit (3) detects the toner on the basis of the output voltage. An adjustment-purpose closed circuit (4) includes a semi-fixed resistor (VR1) and an adjustment inductor (L3) that forms magnetic coupling with the inductor (L1, L2), and causes an inductance of the inductor (L1, L2), a resonance frequency of the resonance circuit (2), an amplitude of the output voltage and a detected toner amount to be adjustable with a variable resistance value of the semi-fixed resistor (VR1).

Abstract: A control circuit of an image forming apparatus outputs a pulse signal. A clock signal generation circuit generates a clock signal, based on the pulse signal. A pulse signal conversion circuit generates a pulse conversion control signal of a voltage value associated with a duty ratio of the pulse signal. An AC voltage generation circuit generates an AC voltage of a frequency based on the clock signal. Either the AC voltage generation circuit or a DC voltage generation circuit generates a voltage whose amplitude or voltage value increases as a voltage value of the received pulse conversion control signal increases, and whose amplitude or voltage value decreases as a voltage value of the pulse conversion control signal decreases.

Abstract: A resonance circuit (2) includes a capacitor (C1) and an inductor (L1, L2) of which an inductance is changed depending on developer including toner, and generates an output voltage corresponding to the inductance. A detecting circuit (3) detects the toner on the basis of the output voltage. An adjustment-purpose closed circuit (4) includes a semi-fixed resistor (VR1) and an adjustment inductor (L3) that forms magnetic coupling with the inductor (L1, L2), and causes an inductance of the inductor (L1, L2), a resonance frequency of the resonance circuit (2), an amplitude of the output voltage and a detected toner amount to be adjustable with a variable resistance value of the semi-fixed resistor (VR1).

Abstract: A fixing device includes a fixing member, a pressing member and a heater. The heater includes a center heating part, end heating parts, a common electrode, a first individual electrode and a second individual electrode. The center heating part is divided into 2n (n?2) center heating elements at intervals in the width direction. The center heating elements each has electrodes on both end faces in a conveyance direction and are connected between the common electrode and the first individual electrode in series. Each of the end heating parts is divided into n end heating elements at intervals in the width direction. The end heating elements each has electrodes on both end faces in the conveyance direction and are connected between the common electrode and the second individual electrode in series.

Abstract: A differential transformer-based permeability sensor includes a substrate including an insulation layer and a wiring layer stacked on each other, a first drive coil, a first induction coil, a second drive coil, a second induction coil, and a adjuster coil, all flatly formed on the wiring layer, a closed circuit including the adjuster coil and a current regulation element connected in parallel to ends of the adjuster coil, and an oscillation circuit. A circuit constituent is formed in which an oscillation signal of the oscillation circuit is provided to each of the drive coils, so that an induction current flows through the first induction coil, the second induction coil, and the adjuster coil, and a difference between the induction current of the first induction coil and that of the second induction coil is outputted. The induction current of the adjuster coil is adjusted according to resistance of a variable resistor.

Abstract: A differential transformer-based permeability sensor includes a substrate including an insulation layer and a wiring layer stacked on each other, a first drive coil, a first induction coil, a second drive coil, a second induction coil, and a adjuster coil, all flatly formed on the wiring layer, a closed circuit including the adjuster coil and a current regulation element connected in parallel to ends of the adjuster coil, and an oscillation circuit. A circuit constituent is formed in which an oscillation signal of the oscillation circuit is provided to each of the drive coils, so that an induction current flows through the first induction coil, the second induction coil, and the adjuster coil, and a difference between the induction current of the first induction coil and that of the second induction coil is outputted. The induction current of the adjuster coil is adjusted according to resistance of a variable resistor.

Abstract: The sensitivity of a sensor that detects the amount or density of magnetic substance is raised. The sensor includes an oscillation circuit, a differential transformer, and an amplification circuit. The oscillation circuit includes a resonance circuit having a coil. The differential transformer includes the coil, as a primary coil, and a secondary coil, and is configured such that, as the amount or density of magnetic substance as a detection target increases, a signal output from the secondary coil increases, and as the amount or density of magnetic substance decreases, the signal decreases. The amplification circuit amplifies the signal, and has, as its frequency characteristics, a frequency band such that, as the frequency of the signal decreases, the amplification factor of the signal increases, and as the frequency of the signal increases, the amplification factor of the signal decreases. The resonance frequency of the resonance circuit falls within the frequency band.

Abstract: Provided is a differential transformer magnetic permeability sensor that accurately suppress a variation of output level of each sensor even if a position shift occurs in forming a detection coil, a reference coil, and a drive coil as planar coils. The differential transformer magnetic permeability sensor includes a first coil layer including a first drive coil constituted of a first wire of a flat winding and a detection coil constituted of a second wire of a flat winding, a second coil layer including a second drive coil constituted of a third wire of a flat winding and a reference coil constituted of a fourth wire of a flat winding. The first drive coil and the second drive coil are connected so that drive current have the same direction, while the detection coil and the reference coil are connected so that induced current have opposite directions.

Abstract: A differential transformer magnetic permeability sensor includes a substrate, a drive coil, a first differential coil, a second differential coil, a first interconnection pattern, and a second interconnection pattern. The first differential coil is disposed at a side of a first surface of the substrate, and an induced voltage is generated therein when the drive coil is driven. The second differential coil is disposed at a side of a second surface of the substrate, and an induced voltage is generated therein when the drive coil is driven. The first interconnection pattern is located on the first surface and allows the first differential coil to serve as a reference coil, and the second differential coil as a sensing coil. The second interconnection pattern is located on the second surface and allows the second differential coil to serve as a reference coil, and the first differential coil as a sensing coil.

Abstract: The sensitivity of a sensor that detects the amount or density of magnetic substance is raised. The sensor includes an oscillation circuit, a differential transformer, and an amplification circuit. The oscillation circuit includes a resonance circuit having a coil. The differential transformer includes the coil, as a primary coil, and a secondary coil, and is configured such that, as the amount or density of magnetic substance as a detection target increases, a signal output from the secondary coil increases, and as the amount or density of magnetic substance decreases, the signal decreases. The amplification circuit amplifies the signal, and has, as its frequency characteristics, a frequency band such that, as the frequency of the signal decreases, the amplification factor of the signal increases, and as the frequency of the signal increases, the amplification factor of the signal decreases. The resonance frequency of the resonance circuit falls within the frequency band.

Abstract: Provided is a differential transformer magnetic permeability sensor that accurately suppress a variation of output level of each sensor even if a position shift occurs in forming a detection coil, a reference coil, and a drive coil as planar coils. The differential transformer magnetic permeability sensor includes a first coil layer including a first drive coil constituted of a first wire of a flat winding and a detection coil constituted of a second wire of a flat winding, a second coil layer including a second drive coil constituted of a third wire of a flat winding and a reference coil constituted of a fourth wire of a flat winding. The first drive coil and the second drive coil are connected so that drive current have the same direction, while the detection coil and the reference coil are connected so that induced current have opposite directions.

Abstract: A differential transformer type magnetic sensor includes a first coil layer, a second coil layer, and an insulating layer formed between the first coil layer and the second coil layer. The first coil layer includes a detection coil and a first drive coil. The second coil layer includes a reference coil and a second drive coil. The first drive coil and the second drive coil are electrically connected together so that a direction of drive current flowing in the first drive coil is the same as a direction of drive current flowing in the second drive coil. The detection coil and the reference coil are electrically connected together so that a direction of induced current flowing in the detection coil is reverse to a direction of induced current flowing in the reference coil.

Abstract: A differential transformer magnetic permeability sensor includes a substrate, a drive coil, a first differential coil, a second differential coil, a first interconnection pattern, and a second interconnection pattern. The first differential coil is disposed at a side of a first surface of the substrate, and an induced voltage is generated therein when the drive coil is driven. The second differential coil is disposed at a side of a second surface of the substrate, and an induced voltage is generated therein when the drive coil is driven. The first interconnection pattern is located on the first surface and allows the first differential coil to serve as a reference coil, and the second differential coil as a sensing coil. The second interconnection pattern is located on the second surface and allows the second differential coil to serve as a reference coil, and the first differential coil as a sensing coil.

Abstract: In an image forming apparatus, the magnetic sensor obtains an output value varying with a magnetic toner amount in a development device. The correlative data storing part prestores correlative data relating to the output value when there is no magnetic toner in the development device and the output value when the magnetic toner amount is a predetermined setting value. The standard value storing part prestores an initial value of a standard value being the output value when the magnetic toner amount is the setting value. The standard value setting part makes the standard value storing part store the output value corresponding to the magnetic toner amount being the setting value, as new standard value, by the output value when there is no magnetic toner in the development device and the correlative data. The toner amount deciding part decides the magnetic toner amount by the output value and the standard value.

Abstract: A differential transformer type magnetic sensor is disclosed. The drive coil includes a planar coil arranged on a substrate. The first differential coil includes a planar coil arranged on the substrate. The second differential coil includes a planar coil arranged on the substrate and connected to the first differential coil. The first selector unit is used for a zero adjustment of a differential transformer. The first differential coil includes a plurality of first branch lines formed by branching a wire material forming the outermost turn of the first differential coil. The plurality of first branch lines are so arranged that the amount of magnetic fluxes passing along the plurality of respective first branch lines differ when the drive coil is driven. The first selector unit is capable of selecting any one of the plurality of first branch lines and arranged on the substrate.

Abstract: A differential transformer type magnetic sensor includes a first coil layer, a second coil layer, and an insulating layer formed between the first coil layer and the second coil layer. The first coil layer includes a detection coil and a first drive coil. The second coil layer includes a reference coil and a second drive coil. The first drive coil and the second drive coil are electrically connected together so that a direction of drive current flowing in the first drive coil is the same as a direction of drive current flowing in the second drive coil. The detection coil and the reference coil are electrically connected together so that a direction of induced current flowing in the detection coil is reverse to a direction of induced current flowing in the reference coil.

Abstract: In an image forming apparatus, the magnetic sensor obtains an output value varying with a magnetic toner amount in a development device. The correlative data storing part prestores correlative data relating to the output value when there is no magnetic toner in the development device and the output value when the magnetic toner amount is a predetermined setting value. The standard value storing part prestores an initial value of a standard value being the output value when the magnetic toner amount is the setting value. The standard value setting part makes the standard value storing part store the output value corresponding to the magnetic toner amount being the setting value, as new standard value, by the output value when there is no magnetic toner in the development device and the correlative data. The toner amount deciding part decides the magnetic toner amount by the output value and the standard value.

Abstract: A high-voltage power supply device for generating a voltage in which a direct-current voltage and an alternating-current voltage are superimposed is provided with alternating-current voltage generating unit generating an alternating-current voltage, and direct-current voltage generating unit generating a direct-current voltage to be superimposed on the alternating-current voltage generated by the alternating-current voltage generating unit. The alternating-current voltage generating unit sets the alternating-current voltage to be generated to such a value that peak values of a voltage superimposed with the direct-current voltage to fall within predetermined voltage values when generating the alternating-current voltage to start the superimposition with the direct-current voltage generated by the direct-current voltage generating unit.

Abstract: This invention relates to an image forming apparatus with a transfer unit for transferring toner electrically to an electrostatic latent image formed on a photoreceptor onto a copy sheet. The image forming apparatus has a transfer electrode charge supply means for supplying electric charges to a transfer electrode provided in the transfer unit to electrically attract the toner onto the copy sheet and control means for controlling the quantity of electric charges to be supplied to the photoreceptor via the transfer electrode from the transfer electrode charge supply means based on a photoreceptor inflow current flowing to the photoreceptor through the charge send/receive means and on a photoreceptor outflow current flowing out from the photoreceptor through a ground wire connecting the photoreceptor and the ground. The charge send/receive means, other than the transfer unit, sends and receives electric charges to and from the photoreceptor.