Abstract: The image density control method in the image forming apparatus including the charging unit for charging the photoconductor, the exposure unit for exposing the photoconductor and forming an electrostatic latent image, and the developing unit for visualizing the electrostatic latent image with toner comprises a step of forming a predetermined reference image by the developing unit, a step of detecting the toner density of the reference image, a step of setting a target density value or the reference image formed on the photoconductor according to the number of images to be formed, and a step of controlling so as to change at least one of the charging potential to be given to the photoconductor from the charging unit, the exposure amount at the time of exposure from the exposure unit to the photoconductor, and the development bias voltage given to the developing unit on the basis of the comparison result of the value detected at the detection step with the target density value set at the setting step.

Abstract: The present invention is directed to an image forming apparatus and its control method, which apparatus having a laser pulse arithmetic circuit for counting a time period in which a laser pulse signal is in an ON state, a temperature sensor for monitoring temperature in a developing unit and output temperature data, a humidity sensor for monitoring humidity in the developing unit and output humidity data, a control section for calculating consumption of toner in the developing unit on the basis of a counted value of the laser pulse arithmetic circuit, temperature data obtained from the temperature sensor and humidity data obtained from the humidity sensor, thereby calculating a toner supply time period to maintain a constant toner amount in the developing unit, and a toner supply section for supplying toner into the developing unit on the basis of the toner supply time period calculated by the control section.

Abstract: An image forming device is proposed in which a photoreceptor can be replaced easily, and in which it is unlikely that an image problem is caused by a grounding failure of a photoreceptor. The image forming device includes a driving unit including a first coupling member having a groove or a projection for transmitting a rotating force, the driving unit being made of a conductive material, electrically grounded, and rotatable; and a photoreceptor assembly as a driven section rotated by said driving unit, the photoreceptor assembly including a photoreceptor and a second coupling member, and being attachable to/detachable from said driving unit, the second coupling member having a projection or a groove for engaging with the groove or the projection of the first coupling member, rotation of said driving unit being transmitted to the photoreceptor by the engagement of the first coupling member and the second coupling member.

Abstract: An impact dot printer head having one or plural heat conductive members. The heat conductive member, with a part in the proximity of armature stopper of the impact dot printer head while another part guided to the outside a housing of the impact dot printer head, conducts heat inside the housing to the outside. Accordingly, as the heat conductive member first conducts heat of the armature stopper to a heat radiation unit outside the housing, degradation of hardness of the armature stopper due to heat can be prevented, and a return position of the armature can be determined in a stable manner.

Abstract: The present invention is a fixing device for use in an electrophotographic apparatus arranged in a structure in which a high-frequency current is flowed through an induction coil provided close to an endless member having a metal layer made of a conductive material and the endless member is caused to generate heat to heat a material to be fixed. This fixing device is characterized in that, when a start-up operation is started by electrically conducting the induction coil, the endless member is rotated after the metal layer reaches a temperature higher than a final setting temperature, and for a predetermined time from starting rotation of the endless member, a high-frequency current having a size corresponding to a control value of a temperature lower than the final setting temperature and higher than a target temperature is supplied to the coil.

Abstract: The color image forming apparatus of the present invention has a plurality of recording medium arranged along a conveying path for forming electrostatic latent images, a plurality of developing units installed respectively in the neighborhood of the plurality of recording medium for feeding developers having different lightness to the respective electrostatic latent images formed on the plurality of recording medium and forming developed images, a plurality of transfer units for multiple-transferring the developed images formed respectively on the plurality of recording medium sequentially on a material to be transferred which is conveyed along the conveying path, and a plurality of collectors for collecting the respective residual developers on the plurality of recording medium after passing the transfer units in the plurality of developing units respectively, and among the plurality of developing units, the developing unit having the developer with lowest lightness compared with the developing unit having t

Abstract: Toners comprise toner mother particles in a mean particle size A [&mgr;m] containing a metallic complex and zinc stearate in a mean particle size 2-A [&mgr;m] externally added to the toner mother particles by 0.05-5.0%.

Abstract: Control signals are input to the gates of a P-MOS transistor and an N-MOS transistor of a CMOS drive circuit from respective control signal generating sections. The CMOS drive circuit drives a piezoelectric member as a capacitive element and the piezoelectric element is used in an ink jet head. A substrate of the P-MOS transistor is provided with a voltage higher than a power supply of the CMOS drive circuit. A first potential difference is supplied between terminals of the piezoelectric element and thereafter, a second potential difference of a polarity opposite to the first potential difference is further supplied between the terminals. A discharge operation is inserted in a time period from the time when supply of the first potential difference is completed till the supply of the second difference gets started. The discharge operating time period is set to a proper value at which a desired operating speed, high reliability and low power consumption are achieved.

Abstract: A fixing apparatus of the present invention includes a fixing roller arranged opposite to a heating roller in a spaced-apart relation, a fixing belt spanned between the fixing roller and the heating roller and adapted to be run in a continuous manner to transmit heat from the heating roller to the fixing roller, a pressure applying roller set in pressure contact with the fixing roller through the fixing belt to heat a to-be-fixed material, by the fixing roller under pressure, and blocking members for blocking openings at those opposite sides of a space defined by the fixing roller, heating roller and fixing belt.

Abstract: A sheet feeder includes a cassette for storing a stack of sheets and pushing up the sheets, a main body case having a port through which the cassette is detachably attached, and a feeding mechanism for feeding each sheet in a feeding direction. The feeding mechanism includes a roller shaft disposed above the cassette attached to the internal place of the port and extending perpendicularly to the feeding direction from a side wall of the case, a pickup roller rotated for taking out the uppermost sheet, and a rise-spoiling member attached to the roller shaft, for spoiling a rise of the sheets when the cassette is withdrawn from the port. Particularly, the rise-spoiling member extrudes downward to a position below an upper edge of the port and extends from the pickup roller to the vicinity of the side wall of the case.

Abstract: An ink jet recording apparatus according to the present invention includes a pressure chamber stored with ink, a nozzle communicating with the pressure chamber and capable of discharging the ink from the pressure chamber, and an actuator for increasing and reducing the capacity of the pressure chamber in response to driving signals from a driving signal generator. The driving signal generator successively generate, an expansion pulse for increasing the capacity of the pressure chamber and a contraction pulse for reducing the capacity of the pressure chamber with a timing such that a time lag between the respective centers of the expansion pulse and the contraction pulse matches the resonance period of a meniscus generated in the nozzle by the ink in the pressure chamber. Thus, the ink jet recording apparatus continuously discharges a plurality of ink drops through the nozzle to form a pixel.

Abstract: A fixing device for an electrophotography system, which is capable of efficiently and uniformly heating an object to be heated, which has a coil capable of being easily produced and which is capable of being stably fixing a fixed material, is provided by preventing the distance between the going and returning portions of a certain turn of the coil from being too close to each other, by preventing the diameter of the coil from changing when the coil is wound, by providing a uniform gap between the coil and the inside surface of the heating roller over the whole length, by preventing the fixing performed by the heating roller to be affected by the turning ON/OFF of a power supply, by preventing noises from being generated from the coil ejecting portion, and by devising the procedure for efficiently winding the coil.

Abstract: In a fixing mechanism which heats a fixation member by generating heat in an endless member by using an induction current obtained from a current flowing through an induction coil, the present invention is characterized in that the induction coil is divided into a plurality of coils in a direction vertical to a moving direction of the fixation member and a coil to which power is supplied is switched according to needs.

Abstract: An image forming apparatus according to the invention includes a photosensitive belt for carrying an electrostatic latent image, a developing roller to be brought into contact with the photosensitive belt for supplying a non-magnetic mono-component developer to the electrostatic latent image carried by the photosensitive belt, thereby forming a developer image, a thickness-limiting blade kept in contact with the developing roller for limiting, to a predetermined value, the thickness of the developer provided on the developing roller, and a transfer unit for transferring the developer image, carried by the photosensitive belt, onto a sheet of paper, wherein the photosensitive belt, the developing roller and the thickness-limiting blade are each made of a metal.

Abstract: A color image processing device is disclosed which has an increased degree of freedom in black-coloring processing and permits color images which have good color reproducibility and are less susceptible to position displacement in black-colored portions to be output. The device includes a minimum detector circuit, a first lookup table for determining the amount of black material (K), a second lookup table for determining the amount of black material (k1) in color materials which has one of 256 values from 0 to 255, a third lookup table for determining the amount by which the underlying color is removed (k2) which has one of 256 values from 0 to 255, and three subtracters and three dividers for processing the outputs of the lookup tables to calculate C′, M′ and Y′ indicating the amounts of color materials used in the printer.

Abstract: When an instruction to start copying is provided, a CPU estimates heat time required until the temperature of a heater of a printer reaches an operating temperature. The CPU also estimates read time required for reading an original document by a scanner. Then, the CPU subtracts the read time from the heat time to obtain standby time and causes the scanner to start reading the original document when the standby time elapses from when the instruction to start copying is provided.

Abstract: There is here disclosed a manual paper feeder attached to an image forming apparatus including at least an image data receiving portion and an image forming device, and the manual paper feeder comprises a manual feed unit for supplying a paper sheet by mounting the paper sheet by a user; and a paper sheet release unit including at least a paper feed roller for carrying the paper sheets mounted in the manual feed unit; a frictional separation member for carrying the paper sheets by the frictional force while holding the manually supplied paper sheets between the frictional separation member itself and the paper feed roller; and a frictional force variable mechanism for changing the frictional force for holding the paper sheet between the paper feed roller and the frictional separation member.

Abstract: A heating mechanism includes a paper transmitting path for carrying a paper, a fixing roller provided on this paper transmitting path, a pressurizing roller disposed so as to oppose the fixing roller, a heating roller provided apart from the fixing roller for applying heat indirectly to the fixing roller, a belt which is wound around the heating roller and the fixing roller in order to transmit a rotation driving force from the fixing roller to the heating roller and thermal energy from the heating roller to the fixing roller and makes a contact with the other side face of the paper passing between the fixing roller and the pressurizing roller, and a pair of first restricting members disposed with a gap from both end faces of the heating roller to guard both sides of the belt on the heating roller thereby restricting a shifting motion of the belt in the width direction.

Abstract: The present invention provides an image forming apparatus, in which a driving device detected by a detecting device sets the control amount in a manner to set the magnitude of the driving signal supplied to first, second and third motors in accordance with generation of the phenomenon for changing the magnitude of the driving signal imparted to the first, second and third motors. In the image forming apparatus of the particular construction, it is possible to suppress the jitter occurrence in the toner image caused by the fluctuation in the load, the fluctuation bringing about fluctuation in the rotating speed of the photosensitive body.

Abstract: When a digital copying machine is switched on, a main CPU confirms whether the current timing is a timing at which an advertisement can be displayed on a display section. If operational inputs are being performed from the display section in the digital copying machine, the advertisement cannot be displayed and thus a normal image forming operation is controlled. If operational inputs are not being performed from the display section and the current timing is the timing at which the advertisement can be displayed, it is conformed whether an HDD stores a registered image as an advertisement image. If there is at least one registered image in the HDD, the at least one registered image is displayed on the display section at predetermined time intervals at the timing of the advertisement display in accordance with the priority level. The registered image in the HDD, whose remaining designated display time has reduced to zero, is deleted.