Abstract: A method for evaluating an electric resistance member of an image forming apparatus which can maintain good image quality, without the occurrence of transfer defects such as insufficient transfer, even in a long-term use. An intermediate transfer belt of the image forming apparatus, which is evaluated based on a fluctuation characteristic of the resistivity in a period of continuous voltage application, is used. The absolute value ??s of the amount of changes in the surface resistivity of the intermediate transfer belt within 2 seconds to 100 seconds from the beginning of voltage application is 0.3 [Log(?/)] or less, when the surface resistivity ?s is measured by applying a voltage of 500 V. The absolute value ??v of the amount of changes in the volume resistivity within 2 seconds to 100 seconds from the beginning of voltage application is 0.5 [Log(?·cm)] or less, when the volume resistivity ?v is measured by applying a voltage of 200 V.

Abstract: A transfer device that transfers color visual images of different colors from image carriers to each of first and second sides of a recording medium. The transfer device includes a transfer element that holds and moves the recording medium, transfer bias applying devices that apply transfer biases to the recording medium by the transfer element to transfer the color visual images from the image carriers to the recording medium, respectively, and an adsorbing bias applying device that applies an adsorbing bias to the recording medium to adsorb the recording medium to the transfer element. A polarity of the adsorbing bias applied to the second side of the recording medium is opposite to that of electric charge given to the recording medium due to electric discharge generated when the recording medium is separated from the image carriers after passing through transfer nip parts formed between the image carriers and the transfer bias applying devices.

Abstract: An electrophotographic color image forming apparatus of the present invention includes a plurality of image forming sections each including an image carrier and image transferring means. Toner images of different colors are sequentially transferred from the image carriers to a sheet being conveyed by an endless belt while electrostatically adhering to the belt, completing a color toner image. Assuming that the surface of each image carrier and that of the belt move at speeds of Vd and Vb, respectively, then a ratio of Vb/Vd can be varied by the user of the apparatus.

Abstract: An intermediate image transfer type of image forming apparatus of the present invention includes an image carrier, an intermediate image transfer body, primary image transferring means for transferring a toner image from the image carrier to the intermediate image transfer body, and secondary image transferring means for transferring the toner image from the intermediate image transfer body to a sheet. When the surface resistivity of the intermediate image transfer body is measured by a method that repeatedly applies a voltage of 200 V for 60 seconds to the intermediate image transfer body and grounds the intermediate image transfer body for 10 seconds 1,000 consecutive times, a difference in absolute value between the logarithm of the first time of measurement and that of the thousandth time of measurement is 0.5 log &OHgr;/□ or below.

Abstract: An image forming apparatus of the present invention disclosed is of the type sequentially transferring toner images from a plurality of photoconductive drums to a sheet being conveyed by an image transfer belt or an intermediate image transfer belt one above the other with bias applying members to thereby form a composite color image. Backup rollers, contacting the inside surface of the belt, each have volumetric resistivity of 109 &OHgr;·cm or above and ten-point mean surface roughness Rz of 6 &mgr;m or above.

Abstract: A transfer device that transfers color visual images of different colors from image carriers to each of first and second sides of a recording medium. The transfer device includes a transfer element that holds and moves the recording medium, transfer bias applying devices that apply transfer biases to the recording medium by the transfer element to transfer the color visual images from the image carriers to the recording medium, respectively, and an adsorbing bias applying device that applies an adsorbing bias to the recording medium to adsorb the recording medium to the transfer element. A polarity of the adsorbing bias applied to the second side of the recording medium is opposite to that of electric charge given to the recording medium due to electric discharge generated when the recording medium is separated from the image carriers after passing through transfer nip parts formed between the image carriers and the transfer bias applying devices.

Abstract: A color image forming apparatus includes a plurality of image forming sections independent of each other. The image forming sections store respective toner of different colors that are chargeable to the same polarity. All the toner are implemented by the same binder resin and provided with the same particle size distribution. Further, developing units each storing toner of particular color are identical in specification. When two-ingredient type developers are used, the developers contain an identical carrier. The apparatus recycles the toner of different colors to the respective developing units. The alien color toner collected in each developing unit is prevented from remaining by being chargeable to the same polarity.

Abstract: An image forming apparatus includes a belt member to convey a sheet-formed medium, a belt supporting device to support the belt member, and a plurality of recording units including rotating image bearing members arranged in a conveying direction of the sheet-formed medium by the belt. The image forming apparatus performs processes of (1) forming a latent image on a surface of each image bearing member, (2) developing each latent image into a toner image with toner, and (3) then transferring each toner image onto the sheet-formed medium carried on the belt. A detection device detects arbitrary toner image patterns formed at the plurality of recording units and then directly transferred onto the belt, for obtaining information about density and placements of images without the toner patterns being deteriorated by contacting following downstream recording units.

Abstract: An image forming apparatus including a plurality of image forming sections each having an electrostatic latent image bearing member to form a latent image on its surface, a charging device to uniformly charge the electrostatic latent image bearing member, a developing device to develop the electrostatic latent image formed on the electrostatic latent image bearing member into a visible image and a cleaning device to remove developer adhered to the electrostatic latent image bearing member. The image forming sections are disposed in series in close proximity to or contacting a transfer sheet conveying belt spanned rotatively and are configured to differentiate an amount of a lubricant to be supplied to the surface of each electrostatic latent image bearing member such that at least one image forming section is differentiated from other image forming sections.

Abstract: An electrophotographic image forming apparatus including an LED (Light Emitting Diode) array head and a method of generating data for correcting the quantities of light to issue form the LEDs of the LED array head are disclosed. Only the quantity of light that actually contributes to development is uniformed throughout the LEDs. This reduces the scatter of a dot area in a latent image and thereby enhances image quality while insuring the sufficient resolution of the LEDs.

Abstract: The present invention is aimed at carrying out high-precision and stable image formation using a gray-level image forming technique. In carrying out image formation by a gray-level electrophotographic process, the relationship between the layer thickness Tp of the photosensitive layer on the photosensitive member and the exposure diameter Db of a light beam emitted onto the photosensitive member is defined as 2Tp <Db, so that the charge diffusion and electric field in the photosensitive layer on the photosensitive member can be small. The maximum exposure within the exposure diameter Db is set at a value that can sufficiently reduce the differential sensitivity of the photosensitive layer, where the exposure diameter Db of the light beam is the minimum diameter at 1/e2 with respect to the peak value of the exposure distribution obtained by integrating the energy distribution of the light beam with the exposure time.