Abstract: An image forming apparatus includes an image bearing member, a developing device, first and second drive portions, and a controller. The developing device includes first, second, and third conveying screws, and a developer bearing member. A ratio of a rotational driving speed (Vsc) of the first and second conveying screws by the first drive portion to a rotational driving speed (Vs1) of the developer bearing member by the second drive portion is Vsc/Vs1. A ratio of a rotational driving speed (Vsc3) of the third conveying screw by the second drive portion to the developer bearing member rotational driving speed (Vs1) is Vsc3/Vs1. In a control mode, the controller controls the first and second drive portions so that Vsc/Vs1 in a non-image forming period becomes less than Vsc/Vs1 in an image forming period such that Vsc3/Vs1 in the non-image forming period is equal to Vsc3/Vs1 in the image forming period.

Abstract: A change of a magnetic flux density distribution adjacent to a regulating blade 9 opposed to a developer regulation pole is suppressed at a low cost, while suppressing influence to design latitude of magnetic poles. A position on the outer peripheral surface of the developing sleeve where the magnetic flux density in the normal line direction of the outer peripheral surface of the developing sleeve is a maximum value position. The position on the outer peripheral surface of the developing sleeve 8 corresponding to a center portion position of the half peak range of the magnetic flux density distribution of the developer regulation pole is called half peak center portion.

Abstract: A change of a magnetic flux density distribution adjacent to a regulating blade 9 opposed to a developer regulation pole is suppressed at a low cost, while suppressing influence to design latitude of magnetic poles. A position on the outer peripheral surface of the developing sleeve where the magnetic flux density in the normal line direction of the outer peripheral surface of the developing sleeve is a maximum value position. The position on the outer peripheral surface of the developing sleeve 8 corresponding to a center portion position of the half peak range of the magnetic flux density distribution of the developer regulation pole is called half peak center portion.

Abstract: A change of a magnetic flux density distribution adjacent to a regulating blade 9 opposed to a developer regulation pole is suppressed at a low cost, while suppressing influence to design latitude of magnetic poles. A position on the outer peripheral surface of the developing sleeve where the magnetic flux density in the normal line direction of the outer peripheral surface of the developing sleeve is a maximum value position. The position on the outer peripheral surface of the developing sleeve 8 corresponding to a center portion position of the half peak range of the magnetic flux density distribution of the developer regulation pole is called half peak center portion.

Abstract: A change of a magnetic flux density distribution adjacent to a regulating blade 9 opposed to a developer regulation pole is suppressed at a low cost, while suppressing influence to design latitude of magnetic poles. A position on the outer peripheral surface of the developing sleeve where the magnetic flux density in the normal line direction of the outer peripheral surface of the developing sleeve is a maximum value position. The position on the outer peripheral surface of the developing sleeve 8 corresponding to a center portion position of the half peak range of the magnetic flux density distribution of the developer regulation pole is called half peak center portion.

Abstract: A change of a magnetic flux density distribution adjacent to a regulating blade 9 opposed to a developer regulation pole is suppressed at a low cost, while suppressing influence to design latitude of magnetic poles. A position on the outer peripheral surface of the developing sleeve where the magnetic flux density in the normal line direction of the outer peripheral surface of the developing sleeve is a maximum value position. The position on the outer peripheral surface of the developing sleeve 8 corresponding to a center portion position of the half peak range of the magnetic flux density distribution of the developer regulation pole is called half peak center portion.

Abstract: An image forming apparatus includes a controller to control a driving device such that a rotational speed of a supplying and feeding screw when it is rotated a predetermined number of times to supply developer to a developing device in a predetermined amount during execution of a continuous image forming job on a plurality of first recording materials is a first rotational speed, and a rotational speed of the supplying and feeding screw when it is rotated the predetermined number of times to supply the developer in the predetermined amount during execution of a continuous image forming job on a plurality of second recording materials is a second rotational speed slower than the first rotational speed. The second recording materials have a length longer than the first recording materials with respect to a sub-scan direction.

Abstract: A change of a magnetic flux density distribution adjacent to a regulating blade 9 opposed to a developer regulation pole is suppressed at a low cost, while suppressing influence to design latitude of magnetic poles. A position on the outer peripheral surface of the developing sleeve where the magnetic flux density in the normal line direction of the outer peripheral surface of the developing sleeve is a maximum value position. The position on the outer peripheral surface of the developing sleeve 8 corresponding to a center portion position of the half peak range of the magnetic flux density distribution of the developer regulation pole is called half peak center portion.

Abstract: A developing apparatus includes a developing container accommodating a developer, a developing sleeve having a plurality of magnetic poles arranged in a circumferential direction, and a regulating member configured to regulate a layer thickness of the developer carried on the developing sleeve. The magnetic poles include a regulation pole disposed opposed to the regulating member such that a maximum value position at which a magnetic flux density in a normal line direction of the developing sleeve is a maximum is not less than 3° away in a circumferential direction of the developing sleeve from a half peak center portion position which is a center portion position of a half-peak width of the magnetic flux density. The regulating member is disposed downstream of the half peak center portion position and upstream of the maximum value position with respect to a rotational direction of the developing sleeve.

Abstract: An image forming apparatus includes an image bearing member; a developing device including a developer container, a feeding member, and a developer carrying member; a toner supplying portion including a feeding screw, and a controller; and a supply rotation number determining portion. The controller controls the driving portion so that the feeding screw is rotated at a first rotational speed when the supply rotation number determining portion determines a number of times of the rotation at a first integer of times of rotation and so that the feeding screw is rotated at a second rotational speed slower than the first rotational speed when the supply rotation number determining portion determines the number of times of the rotation at a second integer of times of rotation smaller than the first integer of times of rotation.

Abstract: An image forming apparatus includes an image forming portion configured to form an image on a recording media and including a developer bearing member configured to bear developer and carry the developer, a regulating portion disposed opposite to the developer bearing member and configured to regulate an amount of the developer on the developer bearing member, a first chamber configured to supply the developer to the developer bearing member, and a second chamber configured to communicate with the first chamber to form a circulating route of the developer. In addition, a first feeding member feeds the developer in the first chamber, and a second feeding member feeds the developer in the second chamber. A control portion executes, in a non-image forming state, a mode of driving the developer bearing member in a condition in which the first feeding member is stopped.

Abstract: An image forming apparatus includes an image bearing member, a developing device, a supplying device, and a control unit. The image bearing member bears a latent image. The developing device develops the latent image with a toner. The supplying device supplies toner to the developing device. The control unit executes a discharge operation to consume toner transferred onto the image bearing member from the developing device without transferring the toner onto a recording medium. The control unit executes the discharge operation where first deterioration integrated information exceeds a first executing threshold, and where second deterioration integrated information exceeds a second executing threshold that is larger than the first executing threshold.

Abstract: An image forming apparatus includes an image forming portion configured to form an image on a recording media and including a developer bearing member configured to bear developer and carry the developer, a regulating portion disposed opposite to the developer bearing member and configured to regulate an amount of the developer on the developer bearing member, a first chamber configured to supply the developer to the developer bearing member, and a second chamber configured to communicate with the first chamber to form a circulating route of the developer. In addition, a first feeding member feeds the developer in the first chamber, and a second feeding member feeds the developer in the second chamber. A control portion executes, in a non-image forming state, a mode of driving the developer bearing member in a condition in which the first feeding member is stopped.

Abstract: A developing device includes a developing container accommodating a developer including toner and magnetic particles, a developer carrying member rotatably provided opposed to an opening of the developing container, a stirring member configured to stir the developer in the developing container to supply the developer to the developer carrying member, a first driving device configured to drive the developer carrying member, and a second driving device configured to drive the stirring member. A controller controls drive of the first driving device and the second driving device so that in a period from output of either earlier one of a stop signal of the first driving device and a stop signal of the second driving device to rotational speeds of both of the developer carrying member and the stirring member becoming not more than ½ of rotational speeds in a steady state during image formation.

Abstract: An image forming apparatus includes an image forming portion having a first feeding member to feed developer in a first chamber, a second feeding member to feed the developer in a second chamber; and a control portion to execute a plurality of modes by suspending image forming. A first mode circulates the developer in a condition in which a ratio of a rotational speed of the developer bearing member to a rotational speed of the first and second feeding members is decreased as compared to that in forming the images; and a second mode increases the ratio of the rotational speed of the developer bearing member to the rotational speed of the first feeding member as compared to that in forming the images. The second mode is executed after the first mode and before resuming the image forming operation.

Abstract: An image forming apparatus that continuously carries out image formation on a plurality of recording materials includes an image bearing member and a developing device configured to develop an electrostatic latent image on the image bearing member. A first feeding screw is provided in a developing chamber and includes a first screw portion, a second screw portion and a third screw portion. Each of the second and third screw portions are provided with a blade portion formed helically on an outer peripheral surface of a rotation shaft of the first feeding screw, and the first screw portion is not provided with the blade portion. Based on information on the relative humidity in the developing container and on the amount of toner consumed with the image formation on a plurality of recording materials, a controller controls a driving speed for rotationally driving the first feeding screw by a driving device.

Abstract: A developing device includes a developer carrying member for carrying a developer; a circulation path along which the developer is circulated; a carrier supplying portion; a discharge opening, provided in the circulation path, through which a portion of the developer is to be overflowed and discharged; and a feeding member comprising a rotation shaft and a blade portion including a helical portion. An outer diameter of the blade portion formed in a first region including at least a portion opposing the discharge opening is smaller than that in a second region adjacent to the first region with respect to a rotation shaft direction. A smaller average angle formed between the rotation shaft and a developer feeding surface of the blade portion in the first region is smaller than that in the second region.

Abstract: A developing apparatus includes a mode in which a control of differentiating a relationship between a rotational speed (Vsc) of a conveying portion (31 and 32) and a rotational speed (Vsl) of a developer carrier (6) in forming no image from that in forming an image is executed. In the mode, the developing apparatus executes at least one of controls of restraining a trouble otherwise caused by the control of differentiating the relationship such as a control of decreasing a ratio of rotational speeds (Vsc/Vsl) as compared to the ratio of rotational speeds in forming the image, a control of circulating the developer between first and second chambers by driving the conveying portion (31 and 32) and the developer carrier (6) at rotational speeds lower than those in forming the image.

Abstract: The present invention suppresses out of balance of developer circulation in a developing device in which a developer carrying member and a stirring member are separately driven. Further, there is provided a developing device preventing an evil effect of an image such as improper coating when a surface of the developer carrying member is coated with a developer. In a period from output of either earlier one of stop signals of motors 7, 8 to rotational stops of both of a developing sleeve 28 and a stirring screw 25 becoming not less than ½ of rotational stops in a steady state during image formation, a ratio ?(E) between the rotational speed of the developing sleeve 28 and the rotational speed of the stirring screw 25 satisfies: 0.7<?(E)/?<2.0 relative to a ratio ? between the rotational speed of the developing sleeve 28 in the steady state during image formation and the rotational speed of the stirring screw 25 in the steady state during image formation.

Abstract: In a constitution in which developer feeding power of a first feeding screw 25 in a region opposing a discharge opening 40 for permitting discharge of a developer, the discharge of the developer is properly made. A blade of the first feeding screw 25 is cut away in a first region including a portion opposing the discharge opening 40. By this, the developer feeding power in the first region is lower than the developer feeding power in a second region adjacent to the first region. A humidity detecting portion as an acquiring portion detects a developer humidity as information on a charge amount of the developer. On the basis of a developer humidity H detected by the humidity detecting portion, a CPU as a control means effects control so that a driving speed at which feeding screws 25 and 26 are driven is faster when the developer humidity is a second humidity higher than a first humidity than when the developer humidity is the first humidity.