A resin member includes a base material and a resin molded body disposed on the base material, the resin molded body containing a main component constituted by an ethylene-vinyl acetate copolymer resin and a carbon black. The resin molded body has two or more peaks within a range of 25 C. to 80 C. in an endothermic curve obtained through measurement performed by heating from 25 C. to 150 C. at 5 C./min with a differential scanning calorimetry (DSC) apparatus.

An image forming apparatus includes: an image forming portion having an image carrying member, a charging device, an exposing device, and a developing device; a developing voltage power supply; a control portion; and an image density sensor. The developing device has a developer carrying member that carries two-component developer and a toner concentration sensor. The control portion senses toner concentration during calibration or during first image formation after calibration for correcting image density based on the sensing result from the image density sensor. If the difference VtargetV between the output value V of the toner concentration sensor actually sensed and a target value Vtarget of the toner concentration sensor to be observed when the toner concentration equals a reference concentration is equal to or larger than a predetermined value, the control portion performs calibration again when the amount of toner consumed after calibration reaches a predetermined threshold value.

An image forming apparatus includes a developing device to contain a developer, the developer including a toner; a developer cartridge to supply the developer to the developing device; a toner concentration sensor to sense a toner concentration of the toner included in the developer contained in the developing device; and a controller. The controller controls, during a non-printing operation a sensor control voltage to adjust an output level of the toner concentration sensor, to control an output of the toner concentration sensor to satisfy a controlling condition, and detects an shape of the output of the toner concentration sensor after the controller controls the sensor control voltage to adjust the output level. The controller adjusts, during a printing operation, the output of the toner concentration sensor, based on the detected shape of the output of the toner concentration sensor, and adjusts supplying the developer from the developer cartridge to the developing device, according to the adjusted output of the toner concentration sensor, to control the toner concentration.

An image forming apparatus includes a control portion, and in a first period from when use of a developing apparatus is started until when an amount of developer in a developing device reaches a predetermined amount larger than an amount of initial developer, when an amount of developer supplied from a supplying portion through a single supplying operation in an image forming operation is larger than a predetermined supplied amount, the control portion interrupts the image forming operation and drives a conveyance portion for a predetermined time. In a second period after the amount of the developer reaches the predetermined amount, when an amount of the supplying developer supplied through a single supplying operation in the image forming operation is larger than the predetermined supplied amount, the control portion continues the image forming operation without interruption.

An image forming apparatus includes an image forming section, a controller, and storage. The storage stores therein a coverage rate of a past image specified by a past print job. The controller includes a determining section and a first calculating section. When a new print job is received, the determining section determines whether or not to perform a running-in operation by comparing a coverage rate of a new image specified by the new print job to the coverage rate of the past image stored in the storage. The first calculating section calculates an amount of toner to be supplied from a developing section to a photosensitive drum based on the coverage rate of the new image. The running-in operation is to supply the toner in the amount calculated by the first calculating section from the developing section to the photosensitive drum before the new image is formed on a sheet.

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).

An image forming apparatus includes an image bearing member, a developing apparatus, a developer accommodating container, a density detecting portion, and, an execution unit. The density detecting portion configured to output an output voltage corresponding to a toner density in the developer container if a control voltage is applied to the density detecting portion. The execution unit configured to execute a mode if an initial setting of the density detecting portion is performed in the state where the developer accommodating container is attached to the image forming apparatus at an attachment position in an initial installation of the image forming apparatus. In the mode, the execution unit sets a preset control voltage as the control voltage to be applied to the density detecting portion when an image is formed.

An image forming apparatus includes: a capacitance detector that detects capacitance of an opposing member disposed opposite to a photoconductor, wherein the capacitance detector detects the capacitance of the opposing member, based on a result of measurement of a current flowing due to potential difference between a voltage applied to the opposing member and the photoconductor being charged.

A mode control section forms a plurality of reference toner images having different densities on a photosensitive drum, where the frequency of an alternating-current voltage of a development bias is varied with a potential difference between direct-current voltages of a development roller and the photosensitive drum maintained constant, generates a reference straight line indicating a relationship between a toner amount of each reference toner image obtained by converting the density of the measured reference toner image into weight, and a representative value of current values of a development current measured during formation of the reference toner image, and acquires the amount of electrostatic charge of toner using the reference straight line.

A powder amount detector is configured to detect an amount of powder in a powder container. The powder amount detector includes a pair of electrodes configured to detect capacitance between the pair of electrodes to detect the amount of powder. The pair of electrodes is flat plate electrodes disposed outside and across the powder container in parallel.