Abstract: An electrophotographic image forming apparatus operable in a monochrome mode and color mode wherein toner images are sequentially formed on an image carrier by toner of a plurality of colors. The toner images of different colors are sequentially transferred to a single transfer member one above the other to complete a color image. In the color mode when toner of two or more colors are to be transferred to the transfer member one above the other, at least one of the color images on the image carrier is discharged before the transfer to the transfer member. In the monochrome mode the image is not discharged before transfer.

Abstract: In an electrophotographic image forming apparatus, a toner images are sequentially formed on an image carrier by toner of a plurality of colors. The toner images of different colors are sequentially transferred to a single transfer member one above the other to complete a color image. When toner of two or more colors are to be transferred to the transfer member one above the other, at least one of the color images on the image carrier is discharged before the transfer to the transfer member.

Abstract: A picture design forming operation detects an adhering amount of toner by an optical sensor in an image forming apparatus. Image forming conditions are controlled on the basis of the detection result and a toner image is formed on a member. The toner image is then transferred to a transferring substance. The transferring substance is then attached to a picture design forming object and is sintered in this state. Further, a light absorbing material which has absorbency to light of a wavelength used in the optical sensor is contained in the toner, and resolves at least at a temperature of the sintering process.

Abstract: An image forming apparatus in which a toner image formed on an image bearing member is first transferred onto an intermediate transfer element and then onto a transfer member. A potential of the image bearing member is detected and a transfer bias voltage applied to the intermediate transfer element is controlled according to the potential of the image bearing member. Undesired images such as transfer blurring due to discharge at the first transfer area, and a solid image scattering and so-called crow's claw mark due to increase of resistance of the transfer member under low absolute humidities are improved.

Abstract: In an image forming apparatus of the type transferring a plurality of toner images of different colors sequentially formed on an image carrier sequentially to an endless intermediate transfer body one above the other by primary transfer, and then transferring the resulting composite color image to a transfer medium by secondary transfer, the intermediate transfer body is provided with surface energy, surface tension or adhering force which is greater than or equal to the corresponding value of the image carrier, but smaller than or equal to the corresponding value of the transfer medium.

Abstract: In an electrophotographic image forming apparatus, a toner images are sequentially formed on an image carrier by toner of a plurality of colors. The toner images of different colors are sequentially transferred to a single transfer member one above the other to complete a color image. According to the number of colors that are to be transferred to the transfer member one above the other, the toner images on the image carrier are controllably discharged before the images are transferred to the transfer member. In addition, the toner images on the image carrier are controllably discharged according to whether the image originates from a computer or scanner.

Abstract: A device incorporated in an image forming apparatus for transferring a toner image from a photoconductive element to an intermediate transfer belt and then from the intermediate transfer belt to a sheet or similar recording medium. An electrode member is implemented as a belt drive roller and located at the rear of a portion of the intermediate transfer belt which lies in a position for transferring the toner image from the belt to a sheet. The electrode member has a specific volume resistance of 10.sup.7 .OMEGA.cm to 10.sup.12 .OMEGA.cm.

Abstract: The apparatus includes a photoconductive element and a transfer belt, with an electrode or bias applicator located downstream from a nip formed between the photoconductive element and the transfer belt. Upstream from the nip, a roller is provided which can also act as an electrode, or which can be held in an electrically floating state. A bias voltage can be provided to the roller upstream from the nip, with the voltage equal to or less than the voltage applied to the downstream electrode so as form a potential gradient. In addition, the applied voltages can be varied based upon the position of a sheet of paper, or in response to changes in humidity.

Abstract: The deposited toner quantity measuring method and image forming apparatus using the same according to the present invention estimates the development characteristics from a quantity of deposited toner obtained by the optional sensor and from a result of detection by the electric potential sensor, and corrects an image signal from the estimated development characteristics.

Abstract: An image forming apparatus includes a photoconductive element and a transfer belt, with an electrode or bias applicator located downstream from a nip formed between the photoconductive element and the transfer belt. Upstream from the nip, a roller is provided which can also act as an electrode, or which can be held in an electrically floating state. A bias voltage can also be provided to the roller upstream from the nip, with the voltage equal to or less than the voltage applied to the downstream electrode. In addition, the applied voltages can be varied based upon the position of a sheet of paper, or in response to changes in humidity.

Abstract: An image forming apparatus which feeds a predetermined bias current smaller than a threshold current to a semiconductor included in digital optics at least during image formation so as to enhance response. During image formation, the apparatus maintains the bias current at an adequate value.

Abstract: A fixing device for an image forming apparatus and having a heating member facing a sheet transport path. The heating member has a number of heating portions which are separate in a direction perpendicular to an intended direction of sheet transport. The heating portions are selectively driven in matching relation to a toner image carried on a sheet.

Abstract: A pretransfer charging device for image forming equipment controls the output of a pretransfer charger thereof in response to an environment sensor or a sensor responsive to the amount of toner deposited on a reference toner image which is formed on an image carrier. The device allows a desired amount of charge to be deposited on a toner during image transfer.

Abstract: An image forming apparatus which insures stable image transfer at all times with no regard to aging and environment. An electrometer is located in close proximity to and opposite to a transfer region where an image carrier and a transfer medium face each other. A voltage to be applied to an electrode which applies a transfe voltage to the transfer medium is controlled in response to the output of the electrometer such that the electric field in the transfer region remains constant.

Abstract: Image forming equipment having an image carrier and a developer carrier located face-to-face and forming an AC-superposed DC electric field between them to develop a latent image electrostatically formed on the image carrier. Sensors responsive to image forming conditions are provided and protected from noise ascribable to an AC component included in the electric field in the event when the sensors operate.

Abstract: An image density control method for an image forming apparatus of the type forming a latent image of a document image on a photoconductive element and developing the latent image by a toner to produce a toner image by an electrophotographic procedure. A background pattern whose density is substantially the same as the background density of a document, i.e., a light pattern is illuminated to electrostatically form a latent image thereof on the photoconductive element. The latent image is developed by the toner, and the density of the resultant toner image is optically sensed by an image density sensor. A change in background density due to contamination or an increase in background potential, for example, is detected. Based on the detected change in background density, a quantity of light for imagewise exposure or similar factor dictating the developing ability is corrected, i.e., it is controlled to the light side if the density has been shifted to the dark side.

Abstract: An image forming apparatus having a developing device of the type using a two-component type developer and developing an electrostatic latent image by a bias electric field having an alternating electric field. A predetermined reference latent image is electrostatically formed on an image carrier by a reference latent image forming device and then developed by the developing device to become a reference toner image. An irregularity detecting circuit determines the degree of difference between the density of the edge and the density of the central portion of the reference toner image. A bias electric field control circuit controls the bias electric field in matching relation to the output of the irregularity detecting circuit, thereby preventing the image quality from being degraded by a change in the resistance of the carrier.

Abstract: An image density control device for an image forming apparatus produces a sufficient output with no regard to the amount of toner deposition on an electrostatic latent image and, based on the output, performs adequate image density control. The amount of toner deposition is sensed by a plurality of reflection type optical sensors each having a light emitting and a light-sensitive element. The angle between the optical axes of the light emitting and light-sensitive elements differs from one sensor to another. The sensor having a large angle and the sensor having a small angle as defined between the optical axes are used to sense a areference density pattern having a relatively low density and a reference density pattern having a relatively high density, respectively. The plurality of optical sensors may be replaced with a single optical sensor which is actuated by a drive mechanism to change the angle between the optical axes in matching relation to the density of the reference density pattern.

Abstract: A device for controlling the density of toner of different colors individually stored in a plurality of developing units which are arranged around a photoconductive element senses toner density at a predetermined period which differs from one of the developing units to another. Each of the developing units is associated with a different kind of toner density sensing device.

Abstract: A light absorbing body is located to adjoin the back of an image carrier which is made of a light transmitting member. A latent image representative of an exclusive pattern for density detection is formed in a non-image region of the image carrier and developed by toner of any of multiple colors to become a toner image adapted for density detection. The toner image is illuminated so that image density is detected in terms of the intensity of light which is reflected by the toner image. The light absorbing body is made up of a plurality of absorbing members each having predetermined absorptivity. The absorbing members are selectively used in association with the spectral reflectivity characteristic of toner.