Abstract: A developing apparatus according to the present invention comprises a developer carrying member for holding a developer and introducing the developer into a developing area opposite to the image carrying member at a required distance; a voltage applying device for applying an AC voltage to the developer carrying member; and a resistor inserted between the developer applying device and the developer carrying member, the AC voltage applied to the developer carrying member from the voltage applying device through the resistor being composed of a rectangular wave, and a time period during which a voltage, which is exerted in the direction in which the developer is fed to the image carrying member, in the AC voltage is less than 50% of a time period during which the AC voltage is exerted.

Abstract: A toner discharging member is in contact with a developing sleeve at a position downstream to a developing region at which the developing sleeve (developer carrying member) confronts an electrostatic latent image carrier, extra toner returning to a toner supply region after the development is brought into contact with the discharging member and moves between the discharging member and the developing sleeve, a discharging bias voltage is applied to the toner discharging member, and the discharging bias voltage thus applied is controlled based on a toner charged state, an adhesion state of toner onto the electrostatic latent image carrier, a current flowing through a toner discharging member and others.

Abstract: An image forming apparatus comprising: a laser beam irradiating device for irradiating a laser beam onto a record support member; a storage device for storing image data composed of a plurality of dots; a detection device which reads out the image data from the storage device so as to detect whether or not dots to be subjected to light emission by the laser beam are arranged continuously; and a control device for controlling an irradiation period of the laser beam irradiating device to a smaller value when the detection device has detected that the dots to be subjected to light emission are arranged continuously.

Abstract: A fixing device of an image forming apparatus for fixing a toner image on a paper by a heating roller and a pressure roller, and having a detector for detecting the temperature of the heating roller. The fixing device controls to supply the electric current to the heating roller intermediately between on state and off state by repeatedly switching on and off the electric current when the difference between the detection temperature signal detected by the detector and a reference temperature signal is within a predetermined value.In detail, the fixing device overlays a periodically changing signal on at least one of the detection temperature signal and the reference temperature signal by a signal convertor so as to control the current supplied to the heating roller in accordance with the comparison result of the detection temperature signal and the reference temperature signal output from the signal convertor.

Abstract: An image fixing device for an image forming apparatus, comprises a hollow cylindrical fixing roller, and cylindrical pressure roller which is kept in contact with the fixing roller so as to rotate in accordance with rotation of the fixing roller. The pressure roller cooperates with the fixing roller to form therebetween a nip extending in a direction of the longitudinal axes thereof and serving to receive a sheet to which a toner image is transferred. The fixing roller is provided with a heater for locally heating the inner wall of the fixing roller at a location corresponding to the nip to fix the toner image to the sheet.

Abstract: A contact type charging device having a contact member for making contact with the surface of a charge bearing member so as to apply an electric charge to the surface in an image forming apparatus of the electrophotographic type, and having a charging device which has a high resistance resistor connected serially to the contact member so as to apply a voltage to the contact member. The contact type charging device has a regulating member for regulating the upper limit of the absolute value of the voltage applied to the contact member to prevent excessive current flow to the contact member, or has a regulating member for regulating the lower limit of the absolute value of the voltage applied to the contact member to prevent a greater than necessary drop of the voltage applied to the charge bearing member.

Abstract: An electric charge supplying device for supplying electric charges to a body to be charged, comprises a charge-supplying member arranged in contact with the body to be charged, a power supply for supplying electricity to the charge-supplying member, and a shunt resistance connected in parallel with a series circuit including the charge supplying member and the body to be charged, the shunt resistance having environmental dependency of resistance substantially equal to that of the charge supplying member.

Abstract: An image forming apparatus is provided with an optical system for forming a first electrostatic latent image and a second electrostatic latent image on a rotatable photosensitive member, a first developing device accommodating a first developer for developing the first electrostatic latent image, and a second developing device accommodating a second developer for developing the second electrostatic latent image. The second developing device is located downstream from the first developing device in a direction of rotation of the photosensitive member and is provided with a developing roller having a magnetic force. The second developer differs in color from the first developer and has a magnetism greater than the first developer. The second developer is transported to the second electrostatic latent image along a periphery of the developing roller.

Abstract: An image forming apparatus accommodates a developing bias power unit for applying a bias voltage to a developing sleeve confronting a photosensitive member. The developing bias power unit includes a DC power source, an electricity storage element interposed between the DC power source and the developing sleeve, and a controller for on-off controlling the DC power source. When an output of the DC power source is activated, the electricity storage element is electrically charged by an output voltage of the DC power source, and a first voltage is applied to the developing sleeve. In contrast, when the output of the DC power source is deactivated, a second voltage of reverse polarity is applied to the developing sleeve by electric charge held in the electricity storage element.

Abstract: A multi-color image forming apparatus which comprises a rotatably supported photoreceptor drum movable sequentially past a first charging station at which the photoreceptor drum is electrostatically charged; a first exposure station at which a first electrostatic latent image is formed on the photoreceptor drum; a first developing station at which a first developing unit is disposed for developing the first electrostatic latent image into a toner image with a first toner material; a second charging station at which the photoreceptor drum is again electrostatically charged; a second exposure station at which a second electrostatic latent image is formed on the photoreceptor drum; a second developing station at which a second developing unit is disposed for developing the second electrostatic latent image into a toner image with a second toner material; a transfer station at which the toner image is transferred onto a recording medium; and a cleaning station.

Abstract: A developing device for developing an electrostatic latent image formed on an electrostatic latent image support member comprises a developer supplying member for supplying a developer to the electrostatic latent image support member, a developer containing portion containing the developer to be supplied to the developer supplying member, a conveying member provided in the developer containing portion for conveying the developer above the bottom part of the developer containing portion to the developer supplying member with the developer in the bottom part of the developer containing portion being left, and an agitating member provided in the developer containing portion for agitating in the developer containing portion the developer remaining in the bottom part of the developer containing portion without being conveyed by the conveying member.

Abstract: A developing device for supplying toner particles to an electrostatic latent image support member having an electrostatic latent image formed thereon to develop the electrostatic latent image comprises a toner conveying member for conveying and supplying the toner particles to the electrostatic latent image support member having the electrostatic latent image formed thereon, a power supply for applying a predetermined developing bias voltage to said toner conveying member, and charge movement preventing means connected between the toner conveying member and the power supply for preventing charges induced in the toner conveying member as the electrostatic latent image is developed from flowing toward the power supply.

Abstract: An image forming apparatus which develops two latent images formed on a photoreceptor with developing agents respectively containing first and second toners of different colors, and is so constructed that, a clear image is obtained by processing mixed-color separation to restrain the mixed-color as much as possible, in response to respective consumptions of a first toner and a second toner, or every time a fixed amount of first toner is consumed, and further, in response to the amount of first toner mixed into a second developing agent detected when a fixed amount of first toner is consumed.

Abstract: An image forming apparatus includes an image support member; a first electrostatic latent image forming device for forming a first electrostatic latent image on the image support member; a first developing device for developing the first electrostatic latent image with first toner; a second electrostatic latent image forming device for forming a second electrostatic latent image on the image support member; and a second developing device for developing the second electrostatic latent image with second toner; the second toner having a color different from that of the first toner and having charging characteristics relative to carrier, identical with those of the first toner; the second toner having an average particle diameter larger than that of the first toner.

Abstract: A color image forming apparatus comprises developing units each of which contains a developer of each of three primary colors, and another developing unit containing a white developer. An image on the original is subjected to color separation to obtain image density data corresponding to each primary color, and when all the density data are lower than a predetermined value, the density data are multiplied by a predetermined ratio, and a predetermined density of a white image is set. Based on the multiplied data of each color a developed image corresponding to the image density data of each primary color is formed on a recording material, and a white image corresponding to the white color density data is on the same recording material, thereby reproducing clear pastel or halftone color images.

Abstract: A first electrostatic latent image on an image bearer is developed with a first toner in a first developing unit, and a second electrostatic latent image thereon is developed with a second toner in a second developing unit, wherein the first toner is transmittable to the image bearer at a lower bias voltage than the second toner, and wherein the second toner and a foreign first toner mixed in the second developing unit are chargeable to the same polarity by friction with a carrier contained in the second developing unit; the second developing unit is put into operation for a non-image forming portion of the image bearer by applying a voltage thereto wherein the voltage is maintained higher than the surface potential of the non-image forming portion so as to enable the foreign first toner to adhere thereto.

Abstract: A developing device having a toner carrying member for transporting toner to a photosensitive member, a toner supplying member facing to the toner carrying member with an opening therebetween for supplying toner to the toner carrying member and a seal member for substantially closing a toner path. In the developing device a scraping member is further provided in contact with the toner supplying member to scrape the toner therefrom and an accommodating space is formed by the toner carrying member, toner supplying member, seal member and scraping member. Thus the toner transported by the toner supplying member is accommodated in the accommodating space and then supplied to the toner holding member under pressure accompanied by the increase of the toner accommodated therein, whereby an adequate quantity of toner is supplied for development.

Abstract: A developing apparatus includes a photosensitive drum positioned in confronting relation to a developing sleeve. A toner accommodating tank is provided for supplying toner to the developing sleeve. The toner accommodating tank is divided into a small chamber and a supplementary chamber which are separated from one another by a partition which permits toner to be supplied from the supplementary chamber to the small chamber but which prevents the return of toner from the small chamber to the supplementary. A movable shutter selectively permits and prevents toner from being supplied from the supplementary chamber to the small chamber in accordance with operation of the apparatus.

Abstract: A developing apparatus for use in an image forming apparatus employing an electrophotographic copying process, which is capable of providing developed images of a constant image quality over a long period of operation. One of the features is an independent section for accommodating toner particles with different particle diameters within the toner hopper. Seventeen separate embodiments serve to assure an adequate mixture of small to large diameter toner particles to assure image quality.

Abstract: An image forming apparatus wherein a photosensitive layer arranged to rotate in one direction is charged by a charger, and a negative electrostatic latent image is formed thereon by an exposure unit and then is subjected to reversal development by a developing device so that a positive noticeable image can be attained. The apparatus has a scorotoron charger for charging the negative latent image which has just been formed by the exposure unit with the opposite polarity thereof. A grid of the scorotoron charger is constituted to be impressed with a voltage with the same polarity as the latent image and a value lower than that of the surface potential, and by the scorotoron charger, the potential of the non-imaged portions of the latent image is lowered around the grid voltage.