Abstract: This image forming apparatus has an image forming unit which is composed of a toner supplying section and a printing section. The printing section includes: an opposing electrode which has a flat part arranged in parallel with the peripheral surface of a toner support; a high-voltage power source for applying a high voltage to the opposing electrode; a control electrode provided between the toner support and opposing electrode; and a cleaning brush. A paper suction portion includes fans as decompressing means and a chamber with a multiple number of suction ports disposed therein, through which air is sucked so that the sheet will not be in contact with the control electrode. Further, a multiple number of grooves are formed in parallel with the sheet conveying direction on the downstream side of the sheet conveying means with respect the sheet conveying direction.

Abstract: A driving circuit includes: a first semiconductor switch with its source connected to a high-voltage power source; amultiple number of diodes with their anodes commonly connected to the drain of the first semiconductor switch; a multiple number of second semiconductor switches, each being connected at the drain to the cathode of the corresponding diode and the sources being commonly connected to a low-voltage power source. In this configuration, the first semiconductor switch is turned on so that all the outputs once have the high voltage supplied and then the plural second semiconductor switches are selectively turned on so as to output the low voltage from their output terminals.

Abstract: An image forming apparatus includes control power source section for controlling a potential to be supplied to a control electrode so that the potential becomes closer to a potential of the holder than a potential on center portions of gates caused by a potential difference across the holder and a counter electrode formed by a high voltage power source section when the charged toner is allowed to pass the gates. In accordance with the above arrangement, the toner receives electric force directing towards the center portions of the gates, and thus a prescribed-shaped dot having a smaller diameter than of the gates is formed on a recording medium. Moreover, since toner does not scatter, a dot to be formed on a recording medium has a clear outline and obtains sufficient density. Therefore, a clear image with high contrast can be obtained. Quality of an image formed on a recording medium can be improved only by controlling the potential to be supplied to the control electrode.

Abstract: A voltage from a high voltage power source is applied between a toner support and an opposing electrode to generate an electric field between the two elements which permits the toner carried on the toner support to jump to the opposing electrode side. A control electrode is provided between the developer support and the opposing electrode to control the jumping of the toner. The control electrode is formed with annular electrodes around gates through which the toner passes through. Each annular electrode is supplied with a voltage for causing the toner to jump or for prohibiting the toner from jumping. In applying the voltage for causing the toner to jump to each annular electrode, the control power source starts to apply a voltage for prohibiting the toner from jumping, to annular electrode at a time when the jumping toner travel past the location of the control electrode. In this situation, the traveling toner continues to move toward the recording paper on the opposing electrode.

Abstract: A voltage from a high voltage power source is applied between a toner support and an opposing electrode to generate an electric field between the two elements which permits the toner carried on the toner support to jump to the opposing electrode side. A control electrode is provided between the toner support and the opposing electrode to control the jumping of the toner. The control electrode is formed with annular electrodes around gates through which the toner passes through. In this arrangement, one or the combination of the followings are featured: At the initial stage of the recording start, the toner support is made to rotate so that the amount of static charge on the toner is stabilized. After the toner is stabilized, the control power source applies a voltage for prohibiting the toner from jumping, to the annular electrodes, then applies a high voltage to the opposing electrode. Thus, the toner can be prevented from erroneously jumping from the toner support.

Abstract: An image forming apparatus includes: an opposing electrode disposed facing a supporting device; a control electrode disposed between the supporting device and the opposing electrode and having a plurality of gates which form passages for the developer particles; a controlling device which generates a predetermined potential difference between the supporting device and the opposing electrode, supplies a voltage to the control electrode, and, by varying the potential applied to the control electrode, controls passage of the gates for the developer particles; and a plurality of voltage supplying device to supply voltages to the control electrode.

Abstract: An image forming apparatus provides a photosensitive body, a main charger, an exposing unit, developing unit and a contact-transfer charger. The main charger charges the photosensitive body with a predetermined electric potential. The exposing unit applies a laser beam on the surface of the photosensitive body to form an electric latent image. The developing unit develops the electrostatic latent image to form a toner image. The contact-transfer charger transfers the toner image on an image transfer paper. The image forming apparatus further provides controller for power supplies. The controller controls the power supplies after an image forming operation in a manner to enhance the electric potential of the photosensitive body to a high level by the main charger, drop the surface potential of the photosensitive body to a low level by the contact-transfer charger and then to cut off a bias voltage of the developing unit.

Abstract: A recording material recognizing device which enables a detection determining whether or not the recording material has passed and a detection determining the width of the recording material to be performed at one time, and also enables a detection determining a thickness, a resistance and a dielectric constant, of the recording material to be performed when physical values of the recording material are also required for stabilizing an image quality.

Abstract: An image forming apparatus provides a photosensitive body, a main charger, an exposing unit, developing unit and a contact-transfer charger. The main charger charges the photosensitive body with a predetermined electric potential. The exposing unit applies a laser beam on the surface of the photosensitive body to form an electric latent image. The developing unit develops the electrostatic latent image to form a toner image. The contact-transfer charger transfers the toner image on an image transfer paper. The image forming apparatus further provides controller for power supplies. The controller controls the power supplies after an image forming operation in a manner to enhance the electric potential of the photosensitive body to a high level by the main charger, drop the surface potential of the photosensitive body to a low level by the contact-transfer charger and then to cut off a bias voltage of the developing unit.