Abstract: At start of rotation of a photosensitive drum, rotation of a developing roller caused by a developing/register rollers driver is kept stopped until a time required for a predetermined point on the photosensitive member, which was located at a charging position when charging thereof by a charging device was started, to reach a development position elapses, and thereafter the developing roller is rotated by the developing/register rollers driver. When the predetermined point on the photosensitive member, which was located at the developing position when at least rotation of the photosensitive member was started, passes the transfer position, a roller cleaning voltage having the same polarity as the charge polarity of toner is applied to a transfer roller.

Abstract: A developing device used in an electrophotographic apparatus has seal members fixedly disposed between both end portions of a developing roller and those portions of inner walls of a device casing which correspond to both end portions of the developing roller. The seal members are made of a material which can be charged by friction with the developing roller to have the same polarity as charged toner. The toner is blocked by the seal members and presented from entering end portions of the developing roller.

Abstract: In a developing device for developing an electrostatic latent image formed on a photosensitive member in an electrophotographic apparatus, a developing roller and a developing blade are formed such that the hardness of the surface of the developing blade is higher than the hardness of the surface of the developing roller by 30 degrees or more in JIS-A hardness. The developing blade deforms and bites into the developing roller. Accordingly, the developing roller can be brought into tight contact with the developing blade, and a great frictional force is applied to the toner passing between the developing roller and blade to fully charge the toner.

Abstract: A transfer device of a contact transfer method wherein a transfer power supply applies a predetermined transfer voltage to a transfer roller contacting the rear surface of a printing sheet, so that an electric field for causing the toner to be attracted by the transfer roller is generated. A lumped constant resistor is electrically inserted between the transfer roller and the transfer power supply. The lumped constant resistor has an electric resistance smaller than an equivalent electric resistance obtained when the whole transfer roller is regarded as one electric resistor. When the electric resistance of the printing sheet changes in accordance with a change in ambient environment, the voltage drop across the lumped constant resistor is changed to compensate for the change in electric resistance of the printing sheet.

Abstract: A developing device used in an electrophotographic apparatus has seal members fixedly disposed between both end portions of a developing roller and those portions of inner walls of a device casing which correspond to both end portions of the developing roller. The seal members are made of a material which can be charged by friction with the developing roller to have the same polarity as charged toner. The toner is blocked by the seal members and prevented from entering end portions of the developing roller.

Abstract: A toner pack for use in an electrophotographic apparatus is formed of a polypropylene resin containing 30 to 50 wt % calcium carbonate filler. This resin has a high deformability, and generates a small amount of heat at the time of incineration thereof. Thus, the used toner pack can be disposed of together with flammable products made of paper and/or wood. Further, at the time of disposal, it is possible to fold the used toner pack to reduce its size.

Abstract: To prevent spurious adherence of toner to the surface of a photosensitive drum during start-up of an electrophotographic printing apparatus, once rotation of the drum and charging of the drum surface to a predetermined potential are initiated, rotation of a developing roller to bring toner into contact with the drum surface is delayed until the charged portion of the drum surface has been rotated around to a position facing the developing roller. Applications of appropriately timed biasing voltages to the developing roller and an image transfer roller are also utilized to prevent spurious toner attraction to the surfaces of the drum and the transfer roller.

Abstract: A transfer device used in an electrophotographic recorder capable of effectively prevent paper jamming and transfer missing in a transfer process which comprises a guide member of an insulating material disposed at a downstream side wall end of a casing and an insulating member of current interruption disposed at an upstream side wall end of the casing, in which the guide member, even when subjected to heat, stably keeps its rigidly mounted state and prevents the falling of the paper into an opening of the casing, and the insulating member of current interruption minimizes the flow of a transfer current from a charging wire toward a small-diameter rubber roller to prevent the transfer missing.

Abstract: A transfer unit has a plastic end block at each end. The end block includes a bearing for supporting an auxiliary roller, and an arm having at its end portion a pivot received by a lower casing. The bearing and the arm are formed integrally with the end block. A leaf spring located under the transfer unit supports it along with the roller in movable relationship around the pivot. When an upper casing is shut down, a photoreceptor drum supported in the upper casing pushes down the transfer unit against the elastic force of the leaf spring. Since the positions of the transfer unit and the roller are determined with respect to the photoreceptor drum, good duplicativity can be obtained. In this state, a cylindrical spacer serves to secure a predetermined space between the photoreceptor drum and the auxiliary roller.

Abstract: A facsimile apparatus for copying a document is described. The apparatus includes an optical system comprising a light source for illuminating a document and a fixed mirror and a lens for guiding the light from the light source reflected by the document. A line sensor converts the light-guided by the optical system into an electrical image signal. An electrostatic recording mechanism including a photosensitive body forms an image corresponding to the light entered onto the photosensitive body on a recording medium. A movable mirror selectively images the light guided by the fixed mirror and the lens onto one of the line sensor and the photosensitive body. A control system switches the position of the movable mirror such that the light guided by the fixed mirror and the lens is imaged onto the photosensitive body when the document is copied and is imaged onto the line sensor when the document is transmitted.

Abstract: A drive circuit for a display device comprises a first input terminal adapted to be connected to receive a drive signal for driving a display device, a second input terminal adapted to be connected to receive a control signal for controlling the driving of the display device, an exclusive OR gate connected to receive the drive signal and the control signals supplied to the input terminals, and an MOS transistor which is turned on and off according to the output level of the OR gate.

Abstract: A voltage controlled oscillator includes three stages of CMOS inverters arranged in cascade connection. The output of the final stage inverter is connected to the input of the first stage inverter. A capacitor is connected between the input and output of any one of the inverters. The inverter with the capacitor connected thereto comprises two MOS FETs of opposite channel types and is connected in series between high and low voltage sources by control MOS FETs of the same channel types as the respective MOS FETs of the inverter. The gates of the control MOS FETs are connected to control terminals to govern the frequency of the oscillator and one additional fine tune MOS FET is connected across each of control MOS FETs to provide fine tuning of the oscillator.

Abstract: A presettable dynamic delay flip-flop circuit including two first and second series-connected 1/2 bit delay circuits, a gate circuit for supplying these delay circuits with a control signal for controlling their operation, and a switching circuit for supplying the second delay circuit with preset data capable of freely presetting the voltage level of an output signal from said flip-flop circuit. The delay circuits and switching circuit are respectively formed of clocked inverters. The flip-flop circuit is formed of a small number of elements and operated at high frequency.