Abstract: An image forming apparatus capable of properly determining replacement time of a developer replenishment unit. An inductance sensor measures a toner density in a developing device. A counter counts the number of pixels of an image to be formed. A toner density-estimating section estimates a toner density in the developing device using the count value output from the counter and a toner replenishment signal output to supply toner from a toner bottle to the developing device. A toner replenishment amount error-estimating section estimates a toner replenishment amount error using the measured toner density and the estimated toner density. When a cumulative value of the toner replenishment amount error becomes equal to or smaller than a predetermined threshold value, it is determined that it is necessary to replace the toner bottle.

Abstract: An image forming apparatus including a replaceable container having toner stored therein includes: an image forming unit including an accumulating unit for accumulating developer containing toner and configured to form an image by using the developer in the accumulating unit; a measurement unit configured to measure a toner density in the accumulating unit; a portion to which the container is attached; a supplementing unit configured to supplement the toner from the attached container to the accumulating unit; and a controller configured to control the supplementing unit based on first information corresponding to a difference between the toner density and a target toner density and second information corresponding to an accumulated value obtained by accumulating differences, wherein the second information does not change in a period from replacement of the container by another container until a predetermined number of times of supplement is performed.

Abstract: An image forming apparatus including a replaceable container having toner stored therein includes: an image forming unit including an accumulating unit for accumulating developer containing toner and configured to form an image by using the developer in the accumulating unit; a measurement unit configured to measure a toner density in the accumulating unit; a portion to which the container is attached; a supplementing unit configured to supplement the toner from the attached container to the accumulating unit; and a controller configured to control the supplementing unit based on first information corresponding to a difference between the toner density and a target toner density and second information corresponding to an accumulated value obtained by accumulating differences, wherein the second information does not change in a period from replacement of the container by another container until a predetermined number of times of supplement is performed.

Abstract: An image forming apparatus including: an image formation unit including an accumulation unit accumulating toner, and forms an image based on image data using the accumulated toner; a measurement unit measures toner density of an developer in the accumulation unit; a replenishment unit replenishes toner to the accumulation unit from an attached container; a first determination unit determines a first value based on the image data; a second determination unit determines a second value based on the measurement result of the measurement result; a third determination unit determines a third value by accumulating the second value; and a controller controls the replenishment unit based on the first value, the second value, and the third value, wherein in a case where the container has been replaced, the third determination unit changes the third value into a predetermined value before the difference is determined by the second determination unit.

Abstract: An image forming apparatus includes an supporting an image bearing member; a developing unit including first and second developer carrying members for developing an electrostatic latent image formed on the image baring member; first and second gap regulating members for regulating gaps between the image bearing member and the first and second developer carrying members, respectively; an urging member for urging the developing unit toward the image forming unit; and a positioning member for positioning the developing unit relative to the image forming unit. The positioning member includes a preventing portion for preventing, while permitting movement of the developing unit in a circumferential direction of the image bearing member at one longitudinal end of the developing unit, movement of the developing unit in the circumferential direction of the image bearing member at the other longitudinal end of the developing unit.

Abstract: An image forming apparatus driving unit includes a rotatable member which is rotatably supported, a pair of bearing portions for rotatably supporting the rotatable member, and a motor for driving the rotatable member. In addition, a driving gear is provided on a driving shaft of the motor, and a driven gear, provided outside the pair of bearing portions with respect to a rotational axis direction of the rotatable member, engages with the driving gear to be rotated integrally with the rotatable member. At least one of the driven gear and the driving gear has, with respect to the rotational axis direction of the rotatable member, a crown shape so that a central tooth surface of a tooth projects more than end tooth surfaces of the tooth at a side where the driven gear and the driving gear engage each other.

Abstract: An image forming apparatus includes an image forming unit for rotatably supporting an image bearing member; a developing unit including a first developer carrying member for developing an electrostatic latent image formed on the image baring member and a second developer carrying member for developing the electrostatic latent image formed on the image bearing member; a first gap regulating member for regulating a gap between the image bearing member and the first developer carrying member; a second gap regulating member for regulating a gap between the image bearing member and the second developer carrying member; an urging member for urging the developing unit toward the image forming unit so that the first gap regulating member and the second gap regulating member are urged against an abutment portion provided on the image bearing member; and a positioning member for positioning the developing unit relative to the image forming unit.

Abstract: An image forming apparatus includes a photosensitive member rotatably supported by a bearing portion provided on a supporting casing; a motor fixed on the supporting casing; a driving gear provided on the supporting casing; and a driven gear for being engaged with the driving gear to be rotated integrally with the photosensitive member. The driven gear includes teeth each of which is crowned such that a tooth thickness is maximum at a maximum tooth thickness position with respect to the gear thickness direction. A maximum force receiving position of the tooth where a force received by the driven gear from said driving gear is maximum when the photosensitive member is driven is different from the maximum tooth thickness position. The tooth thickness decreases from the maximum tooth thickness position toward the maximum force receiving position at a first degree and decreases from the maximum tooth thickness position away from the maximum force receiving position at a second degree, by the crowning.