Abstract: A color image forming apparatus for forming an image through an electrophotographic process, the apparatus having an electrophotographic photosensitive member; charging device for charging the photosensitive member; exposure device for exposing the photosensitive member to light information to form an electrostatic latent image; a color developing device for developing the electrostatic latent image with color toner; a black developing device for developing the electrostatic latent image with black toner; control device for controlling an image forming operation condition to change an image quality; first integrating device for integrating an amount of color image output; second integrating device for integrating an amount of black image output; wherein the control device is responsive to a predetermined output of the first integrating device and to a predetermined output of the second integrating device which is different from the predetermined output of the first integrating device, and wherein the control

Abstract: An image forming apparatus includes an image bearing member electrostatic latent image forming device for forming an electrostatic latent image on the image bearing member, the image forming device forming, on the image bearing member, an electrostatic latent image usable for controlling image formation. A developing device is provided for developing an electrostatic latent image on the image bearing member, a density difference detecting device is provided for detecting a density difference in an image for the control developed by the developing device, and a control device is provided for controlling a developing condition of the developing device on the basis of an output of the density difference detecting device.

Abstract: An image forming apparatus includes an image bearing member for bearing an image, the image bearing member being rotatable at a first speed and a second speed which is different from the first speed, wherein during image formation on the image bearing member, the first speed is selected, and after completion of image formation on the image bearing member, a speed of rotation of the image bearing member is switchable from the first speed to the second speed; a discharger for electrically discharging the image bearing member at a discharging position, the discharger discharging the image bearing member at least one turn after the trailing edge of the image on the image bearing member passes through the discharging position and before the speed of the image bearing member is switched from the first speed to the second speed.

Abstract: A charging device includes a member to be charged; a charging member for charging the member to be charged, the charging member being contactable to the member to be charged and being supplied with a voltage; and wherein upon switching of the voltage from a DC component mode to a superimposing component mode of a DC component and an oscillation component, the DC component is decreased, and a peak-to-peak voltage of the oscillation component is increased in a period, and wherein the peak-to-peak voltage is changed from a first voltage which is smaller than twice a charge starting voltage of the member to be charged to a second voltage which is twice the charge starting voltage, while the peak-to-peak voltage is increasing.

Abstract: A developing apparatus includes a toner carrying member, disposed opposite an image bearing member for bearing an electrostatic image, for carrying toner to the image bearing member; an electric field forming device for forming an alternating electric field between the image bearing member and the toner carrying member, wherein the alternating electric field includes a first phase in which a constant electric field for urging the toner from said image bearing member toward said toner carrying member continues for a predetermined period, a second phase in which a constant electric field for urging the toner from said toner carrying member toward said image bearing member continues for a predetermined period, and a third phase in which the electric field gradually changes from that in the first phase to that in the second phase within a predetermined period .DELTA.T, and a controller for changing a ratio (.DELTA.T/T), where T is one period of the alternating electric field.

Abstract: An image forming apparatus includes an image bearing member for bearing an image of toner and a charging member contactable to the image bearing member to charge the image bearing member. The charging member is adapted to receive a voltage and the toner has a melt index of not less than 0.5 g/10 min. In the apparatus,P/(V.times.L).ltoreq.50J/m.sup.2where v is a movement speed of the image bearing member when the image bearing member is charged by the charging member (m/sec), L is an effective charging length of the charging member, measured in a direction perpendicular to the movement direction of the image bearing member (m), and P is an amount of electric power consumed by the charging member (W).