Abstract: A method and apparatus for controlling the image density of a copy of a special document original with a large image density variation. When a special document original is to be copied, the surface potential of a photoreceptor is set to a level lower by a predetermined value than that employed for an ordinary document original copying operation. Thus, the image density of the resulting copy is comprehensively reduced, and the image density variation in the copy is moderated. Further, the amount of light emitted from the light source for illumination of the document original is set to a predetermined level adapted for a low density document original. Thus, the image density of the copy is prevented from being reduced too much. The level of development bias to be applied to a developing unit corresponding to at least a predetermined standard density level is set to a level higher by a predetermined value than that employed for an ordinary document original copying operation.

Abstract: A development apparatus for developing a latent image formed on an image forming body with a developer so as to obtain a toner image. A developer conveyance unit conveys the developer, including a toner, to a development zone, between the developer conveyance unit and the image forming body, from an upstream side of the development zone in a conveyance direction to a downstream side thereof. A plate member having an electrode portion is positioned at the upstream side of the development zone, wherein a downstream end portion of the plate member is positioned in contact with the development zone. A power supply unit applies a first voltage, including a DC component and an AC component, to the developer conveyance unit so that an electric field is generated at the development zone. The power supply unit applies a second voltage, including a DC component, to the electrode portion of the plate member, and the plate member controls the electric field with the second voltage. The development apparatus satisfies: V.

Abstract: An image forming apparatus performs an electrophotographic process including a uniform charging step, an exposure step, a developing step and a transfer step on a photosensitive drum which is driven so that an image is formed on a recording medium.

Abstract: A developing apparatus includes a developer carrying member, disposed opposed to an image bearing member, for carrying a developer; a developing bias voltage applying source for applying a developing bias voltage having an oscillating component to the developer carrying member to develop an electrostatic latent image formed on the image bearing member; wherein10.0.ltoreq.T11/(T11+T12).times.100.ltoreq.90.0,where T11 is a time period of a first step in which an electric field is formed in a direction for directing the developer from the developer carrying member toward the image bearing member in one cycle of the oscillating component of the developing bias voltage applied by the developing bias application source, and T12 is a time period of a third step between the first step and a second step in which an electric field is formed in a direction for directing the developer from the image bearing member to the developer carrying member, and T11/(T11+T12) is an inclination of the developing bias voltage.

Abstract: By altering a developing bias, a plurality of patch images are formed on a photoconductor, and a density of each patch image is measured, thereby judging whether or not a target density value is within a range of the plurality of measured density values. If the target density value is outside the range, a developing bias which realizes the target density is obtained by an interpolation, in accordance with two measured density values that are closest to the target density value among a plurality of measured densities, and with a developing bias of two patch images that are related to these two measured density values.

Abstract: An image forming apparatus having a voltage generating circuit for generating a bias voltage which is supplied to a developing unit upon reception of a discharge voltage from the charger, for charging a photosensitive drum, based on the discharge voltage. The voltage generating circuit is controlled by a timing signal supplied from the CPU, so that the bias voltage is applied to the developing unit when the photosensitive drum rotates by a predetermined angle and is set at a position where development is carried out.

Abstract: An electrostatic recording control method wherein there are provided a single surface potential sensor between a first and second developer units, a detector for detecting the characteristic of a factor influencing the dark attenuation characteristic of the sensitive body, comprising the steps of: irradiating the surface of a charged sensitive body with the test pattern having prescribed exposure energy by an exposure system to form a test electrostatic image on the photosensitive body; passing the test electrostatic latent image with the developing function of the first developer unit stopping to measure the surface potential of the test electrostatic latent image by the sensor; changing the control setting potential at a position where the sensor is set according to the output from the detector; comparing the potential measured by the passing step with the control setting potential changed by the changing step to control one of the voltage to be applied to the latent image forming charger and the exposure e

Abstract: A developing method includes the steps of opposing a developer carrying member to an image bearing member, the developing carrying member carrying a developer to the image bearing member for bearing an electrostatic image, supplying, to the developer carrying member, insulative one component developer having a weight average particle size of 4-8 microns, forming, between the image bearing member and the developer carrying member, an alternating electric field having a back-transfer period, transfer period and rest period, wherein a blank ratio of a sum of (i) the back-transfer period plus (ii) the transfer period and the rest period, during a developing operation, is 5:1-2:1.

Abstract: A back electrode roller is connected to a back voltage applying circuit. When a sheet of paper is not located at a position corresponding to toner passage apertures, or when a non-printing portion of the sheet of paper is located at the position corresponding to the apertures, an inhibiting voltage for preventing attraction of the toner is applied from the back voltage applying circuit to the back electrode roller. Accordingly, even when the toner erroneously passes through the apertures, the attraction of the toner toward the back electrode roller can be prevented by the application of the inhibiting voltage.

Abstract: In an image forming apparatus, flying of toner from a toner holder towards a counter electrode is controlled by giving a potential to a control grid according to an image signal. Here, a distance between the control grid and the toner holder is set so as to be shorter than a pitch of a gate. The toner passes through a plurality of gates which is a passing section of the toner in the control grid and adheres to a sheet so as to form an image on the sheet. Furthermore, in the image forming apparatus, image signals to be inputted serially from an image reading unit are distributed to odd lines and even lines so as to respectively stored into the odd memory and the even memory. The image signals are stored into the odd memory and at the same time the image signals stored in the even memory are read out.

Abstract: A developing apparatus for developing an electrostatic latent image on an image retainer with two-component developer has a rotatable sleeve having a closest position on which the sleeve comes closest to the image retainer, a first magnet fixed in the sleeve in close proximity to the closest position, a second magnet disposed upstream of the first magnet in relation to a rotation direction of the sleeve and a control electrode member. The control electrode member includes an insulating plate member arranged either to be brought into contact with or to be positioned adjacent to the sleeve and a line-shaped electrode member fixed to the plate member.

Abstract: An image forming apparatus capable of preventing a toner from being left on a photosensitive member upon turning off a developing bias for jumping development. A phase detecting circuit generates a phase detection signal which becomes H level when the developing bias is positive, whereas becoming L level when the developing bias is negative. A phase controller generates a phase-controlled developing bias off signal to an output controller at a timing when the phase detection signal changes from H level to L level for the first time after the phase controller receives a developing bias off signal from a CPU. Then, the output controller stops oscillation of an oscillating circuit, thereby turning off the developing bias at a timing when the toner has returned from the photosensitive member to a developing unit. Accordingly, the toner is prevented from being left on the photosensitive member upon turning off the developing bias.