A developing device of an image forming apparatus includes a casing, two-component developer accommodated in the casing, and a stirring screw for conveying and stirring the developer in the casing by rotation in a predetermined direction. The image forming apparatus includes a toner concentration sensor that outputs a value indicative of the toner concentration of the developer in the casing. The image forming apparatus determines whether or not the developer in the casing has become uniform, based on the amount of change per unit time of the output value of the toner concentration sensor, acquired after the stirring of the developer in the casing by the stirring screw is started. It is possible to appropriately measure the reference value of the toner concentration.

A fluid detection apparatus to detect quantity of a fluid having flowability and stored in a casing includes an oscillator disposed outside the casing to output a frequency of an oscillation signal corresponding to a magnetic flux passing through a space near the oscillator, a vibrator made of material effecting the magnetic flux and disposed inside the casing, a vibration trigger disposed inside the casing to vibrate the vibrator, and circuitry to acquire frequency-related information related to the frequency of the oscillation signal output from the oscillator, detect the vibration of the vibrator based on a change of the frequency-related information, determine whether the vibration of the vibrator converges during a convergence-checking time period defined after the vibrator is vibrated by the vibration trigger, and detect the quantity of the fluid in the casing based on a convergence determination result of the vibration of the vibrator.

Provided is an image forming apparatus that reduces replacement frequency for waste toner container, and efficiently performs waste toner accommodation with a waste toner container. The image forming apparatus includes a toner detection sensor detecting a quantity of a toner in a toner container; a waste toner detection sensor detecting an accommodation quantity of a waste toner removed from a photosensitive medium and accommodated in a waste toner container; a waste toner container full-state forecasting part that, upon toner detection sensor detecting empty state of toner container, forecasts whether waste toner container is filled up with waste toner before toner container newly loaded is emptied, on detection result by waste toner detection sensor; and a system control part that, upon waste toner container full-state forecasting part forecasting waste toner container being filled up, notifies a replacement message urging replacement of waste toner container to a panel part.

A developer including developer particles. Each developer particle includes a binder resin, a brilliant pigment whose principal component is aluminum, a yellow pigment, a magenta pigment, a reddish-orange fluorescent dye, and a yellow fluorescent dye. When an average particle diameter of the brilliant pigments included in the developer particles is expressed as D (m), a number proportion of the developer particles having particle diameters in a range from 4 m to 1.2D m in the whole developer particles is less than or equal to 4%.

A method and apparatus for discriminating bottle types, for stirring the toner, and for detecting the amount of toner remaining in the toner bottle. A toner bottle is adapted to fit the apparatus for discriminating toner bottle types, and a toner bottle is adapted for the apparatus for stirring toner. The genuineness of the toner bottle product is checked by sensing a rib assumed to be formed with a predetermined length on the outer surface of the toner bottle. Toner is stirred by continuously rotating the toner bottle in forward and reverse directions. The toner bottle can be easily rotated in the forward and reverse directions by sensing the rib of the toner bottle by using the sensor. Since the load of rotation of the toner bottle changes in accordance with the amount of remaining toner, the rotational speed of the toner bottle is sensed by using the sensor to check whether toner is close to empty.

An image forming apparatus includes an image forming station configured to form a toner image and a recording material; a fixing portion configured to fix the toner image formed by the image forming station on the recording material; a selector configured to select a correction level for correcting crease of an envelope, by an operator; and a controller configured to control a fixing condition in response to the correction level selected on the selector.

A powder amount detector includes a vibration plate secured to a powder container to contain powder and positioned at a predetermined position in a stationary state, a shaft to rotate inside the powder container, a contact member attached to the shaft, a vibration detector to detect vibration of the vibration plate, and a detection result processor to determine an amount of the powder in the powder container according to a detection result generated by the vibration detector. The contact member is to flip the vibration plate to cause the vibration plate to repeat elastic deformation and reversion to vibrate. The contact member is to exit an area opposed to the vibration plate after the contact member flips the vibration plate by the time the vibration plate returns to the predetermined position.

A development device includes a developer accommodating part that accommodates a developer, a developer detection member that is rotatably supported inside the developer accommodating part and is for detecting an amount of the developer accommodated inside the developer accommodating part, a rotational drive member that rotates the developer detection member around an rotational axis, and a conductive contact member that is formed of a conducive material. Wherein, defining a rotary track through which the developer detection member passes while rotating, a free edge of the contact member is arranged within the rotary track such that the contact member comes in contact with the developer detection member once while the developer detection member makes one rotation, the free edge being distal from where the contact member is fixed.

A powder supply device that includes a powder reservoir including a rotator having a rotation shaft, to store powder supplied from a powder container; and a powder amount detector. The powder amount detector includes a detected member disposed in the powder reservoir, a contact member attached to the rotation shaft, to contact the detected member to vibrate or move the detected member, a detector to detect vibration or a displacement of the detected member, and a detection result processor to detect the amount of the powder in the powder reservoir based on detection by the detector. The powder supply device further includes a controller to supply the powder from the powder container to the powder reservoir based on detection by the powder amount detector. The controller rotates the rotator in discharging the powder from the powder reservoir and supplying the powder from the powder container to the powder reservoir.

Provided is an image forming apparatus that reduces replacement frequency for waste toner container, and efficiently performs waste toner accommodation with a waste toner container. The image forming apparatus includes a toner detection sensor detecting a quantity of a toner in a toner container; a waste toner detection sensor detecting an accommodation quantity of a waste toner removed from a photosensitive medium and accommodated in a waste toner container; a waste toner container full-state forecasting part that, upon toner detection sensor detecting empty state of toner container, forecasts whether waste toner container is filled up with waste toner before toner container newly loaded is emptied, on detection result by waste toner detection sensor; and a system control part that, upon waste toner container full-state forecasting part forecasting waste toner container being filled up, notifies a replacement message urging replacement of waste toner container to a panel part.