Abstract: A cleaning device for a SCOROTRON type electrostatic charger to be used in an image forming apparatus such as a copying machine wherein both discharge wire and grid wire are cleaned by reciprocating a first cleaning member which is contactable with the discharge wire of the electrostatic charger and a second cleaning member contactable with the grid wire. Also, the respective cleaning members are alternately brought into contact with the respective discharge and grid wires in the forward stroke and return stroke of the first and second cleaning members.

Abstract: A motor control device is used for controlling a DC motor for secondary paper feeding in, for example, a copying machine. Secondary paper feeding of paper to a transfer drum is achieved by the dedicated DC motor. The DC motor is rotated at a high speed at the time of starting the secondary paper feeding and is decelerated up to a process speed after a constant time. At the time of the deceleration, the control device applies a short-circuiting brake to the motor. In the short-circuiting brake, there is no variation in braking, thereby to make it possible to reliably decrease the speed of the motor. The braking is released at the timing at which an FG clock corresponding to the rotation of the motor is synchronized with a command clock representing the process speed. Consequently, a braking operation is reliably released the instant the speed of the motor reaches a desired process speed.

Abstract: A transfer unit of an image forming apparatus includes a transfer device, a pressing member, and a regulative member. The transfer device is provided adjacent to a photoconductor of the image forming apparatus and is separable from the photoconductor under its own weight. The pressing member presses the transfer device against the photoconductor. The regulative member regulates the distance by which transfer device is separated from the photoconductor when the pressing member disengages the transfer device therefrom. In this transfer unit, if a printing sheet is large, the pressing member disengages the transfer device after a given transfer operation. As a result, the transfer device separates from the photoconductor under its own weight, with the distance separating the transfer device from the photoconductor being regulated by the regulative member. Then, the transfer device idles in the separated state, wherein preparation for a subsequent transfer operation is made.

Abstract: A nipping device is provided in a transfer unit having a fixed support and rotating element rotatably supported by the fixed support. The nipping device retains a printing sheet against the circumferential surface of the rotating element, and separates the printing sheet from the transfer unit. The nipping device includes a nipper, a pivoting lever device and a drive device. The nipper is disposed pivotally on the circumferential surface of the rotating element, and retains the feed-leading edge of the printing sheet. The levers of the pivoting lever device are disposed within the rotating element, pivotal on an axes intersecting the circumferential surface of the transfer unit, and functions therein to open and close the nipper by which the printing sheet is nipped against and separated from the transfer unit. The drive device is disposed in the fixed support, and functions to turn the pivoting levers.

Abstract: In an image forming apparatus in which toner is fed to a developer unit from a toner storage container through toner conveying means provided between the toner storage container and the developer unit, the image forming apparatus comprises a toner remaining amount detector for detecting not more than a predetermined amount of toner in the toner storage container, a toner density detector for detecting the density of toner in the developer unit, and means for interrupting the image forming operation to feed the toner to the developer unit from the toner storage container through the toner conveying means when the amount of the toner in the toner storage container is larger than the predetermined amount and the density detected by the toner density detector is lower than a predetermined density.

Abstract: A copying paper feeding device for an intermediate tray for use in a copying machine having functions of creating a copy on both sides of a paper or printing a compound copy. In the device while being pressed by a push-out roller, copying papers fed into the intermediate tray are delivered by the rotation of the push-out roller in the direction of a copying paper aligner located downstream and upper-positioned copying papers are pushed out a little further than lower-positioned copying papers in response to a counted number of copying papers fed into the intermediate tray.

Abstract: A photoconductive drum device for electrostatic copying machines or the like includes a temperature maintaining heater bent to a cylindrical form and accommodated in the main body of a photoconductive drum. The heater is constructed with a base plate and a heat generator attached to the base plate. The base plate has a parallelogrammatic form substantially corresponding to a shape which is obtained by cutting a hollow cylinder, having a diameter approximate to the inside diameter of the drum main body, along a helical cut line and unbending the cylinder.