Abstract: To provide a printer capable of minimizing the effect of a wrapping member, which is used for wrapping a recording form around a photoconductor, on image quality and realizing high image quality printing, a conveying roller 6, wrapping roller 8, and transfer units 36a and 36b are arranged so that a line La connecting a center Ca of a roller 38a and a transfer point Ta and a line Lb connecting a center Cb of a roller 38b and a transfer point Tb are inclined to a central line A-A and are almost symmetric to the central line A-A. When the wrapping width W of the form around belt photoconductors 32a and 32b is specified to 5 mm?W?25 mm, even when a wrapping roller is not arranged between printing units 30a and 30b, a fixed wrapping width of the form S around the belt photoconductors 32a and 32b is reserved.

Abstract: In a charging device having saw-tooth electrodes for generating corona discharges, an amount of dust, toner, or paper dust attached to the tip end portions of saw-tooth electrodes is reduced. First to third pairs of saw-tooth electrode plates are disposed in a side-by-side fashion along the periphery of a photosensitive drum in which the first pair is disposed at an upstream side with respect to a direction in which the photosensitive drum rotates, the third pair at a downstream side, and the second pair at a central portion between the remaining two. A current flowing per a unit length of the second pair is set to 1.3 to 3 times as much as a current flowing per a unit length of each of the first and third pairs. The currents flowing per a unit length of the first and third pairs are set to be equal to each other.

Abstract: A perfecting press apparatus for forming images on both sides of a transfer medium. With respect to a transferring current Ipt of an image forming unit, current Ipc is made large which flows from a charge control instrument for controlling charge polarity of the toner on the transfer medium in the direction of the transfer medium. In particular, in the image forming unit causing retransfer, a de-charging light source is installed between the a developing device and a transferring device for canceling charges other than at a latent image part of an image carrier, so that the relationship between Ipt and Ipc is to be 3×Ipc≦Ipc≦6×Ipt, whereby the retransfer is suppressed to minimum for producing satisfied quality of image.

Abstract: A perfecting press apparatus for forming images on both sides of a transfer medium. With respect to a transferring current Ipt of an image forming unit, current Ipc is made large which flows from a charge control instrument for controlling charge polarity of the toner on the transfer medium in the direction of the transfer medium. In particular, in the image forming unit causing retransfer, a de-charging light source is installed between the a developing device and a transferring device for canceling charges other than at a latent image part of an image carrier, so that the relationship between Ipt and Ipc is to be 3×Ipc≦Ipc≦6×Ipt, whereby the retransfer is suppressed to minimum for producing satisfied quality of image.

Abstract: An image forming apparatus has an endless belt which serves as an image carrier is characterized by reduced image misregistration and reduced machining cost. When the endless belt feed path is divided into a path from a drive roller to a tension roller, and a path from the tension roller to the drive roller, the eccentricity of an idle roller located on the path on the side including a latent image forming point is set to a value smaller than that of an idle roller located on the path not including the image forming point.

Abstract: An image forming apparatus comprising an endless belt as an image carrier characterized by reduced image misregistration and reduced machining cost. When the above stated endless belt feed path is divided into a path from a drive roller to a tension roller, and a path from the tension roller to the drive roller, the eccentricity of the idle roller located on the path on the side including a latent image forming point is set to a value smaller than that of the idle roller located on the path not including the image forming point.

Abstract: An image production apparatus includes at least one image production unit having a latent image forming device for forming a latent image on an image carrying member and a developing device for attaching toner to the latent image formed by the latent image forming device. A toner image formed by the image production unit is transferred to a transfer medium to produce an image. The image production apparatus further includes a periodicity giving device for giving periodicity to movement in a main scanning direction of the image carrying member or transfer medium. According to this periodicity, the movement time from an image forming position to a transfer position, or the movement time of a transfer medium between adjacent transfer positions is set equal to an integral multiple of the period.

Abstract: In an image forming apparatus, attachment/detachment guide pins (10 and 11) are disposed on a side face of a belt cartridge (12). Attachment/detachment guide grooves (30, 31, and 32) which guide the attachment/detachment guide pins (10 and 11) are disposed in a frame (29) of a main unit of an image forming apparatus. A belt tension applying mechanism including a tension link (13) and a spring (15) is disposed on the side of the apparatus main unit. When the belt cartridge (12) is to be attached to the apparatus main unit, the cartridge is attached along the attachment/detachment guide grooves (30, 31, and 32), so that the rotation shaft of a tension roller (4) is easily and surely engaged with the belt tension applying mechanism (13 and 15).

Abstract: An image production apparatus includes at least one image production unit having a latent image forming device for forming a latent image on an image carrying member and a developing device for attaching toner to the latent image formed by the latent image forming device. A toner image formed by the image production unit is transferred to a transfer medium to produce an image. The image production apparatus further includes a periodicity giving device for giving periodicity to movement in a main scanning direction of the image carrying member. An amplitude of the period given by the periodicity giving device is larger than a variation amount in the main scanning direction for determining reversal of the movement in the main scanning direction of the image carrying member.

Abstract: In an image forming apparatus, attachment/detachment guide pins 10 and 11 are disposed on a side face of a belt cartridge 12. Attachment/detachment guide grooves 30, 31, and 32 which guide the attachment/detachment guide pins 10 and 11 are disposed in a frame 29 of a main unit of an image forming apparatus. A belt tension applying mechanism including a tension link 13 and a spring 15 is disposed on the side of the apparatus main unit. When the belt cartridge 12 is to be attached to the apparatus main unit, the cartridge is attached along the attachment/detachment guide grooves 30, 31, and 32, so that the rotation shaft of a tension roller 4 is easily and surely engaged with the belt tension applying mechanism 13 and 15.

Abstract: A transport roll 1 consists of a metal roll 3 of 40 mm in diameter covered with a conductive PFA tube 2 of 10.sup.10 .OMEGA.cm in volume resistivity and 200 .mu.m in thickness. A DC voltage source 4 is connected to the metal roll. A sheet of paper 5 bearing toner images 6 and 7 on both sides thereof receives a drive force from a paper drive roll, and turns with the movement of the paper. The DC voltage source produces voltage VB1 of the same polarity as the charging polarity (positive) of the toner image 6 being in contact with the transport roll. The voltage VB1 is optimumly controlled so as to prevent the transport roll from being soiled with toner.

Abstract: There are provided a paper separating mechanism for bringing paper into a state of non-contact with a paper carrying roll; a motor for independently driving the paper carrying roll; and a switch for changing-over the paper carrying roll driving mode between a following mode and an independent driving mode so that the driving mode is changed over to the following mode and independent driving mode at the time of printing and at the time of non-printing, respectively.

Abstract: In an electrostatic printing apparatus, the residual image phenomenon conspicuously observed at low density printing can be eliminated while photo-deterioration of the photosensitive body is being suppressed to a minimum in a high speed printing process. A charging unit, a writing light source, a developing unit, a transfer unit, a first erase lamp, an AC discharging unit and a second erase lamp are arranged around a photosensitive drum. Therein, the light intensity of the erase lamp is strengthened when the density of a printed image is light and is weakened when the density of the printed image is dark. That is, by changing the light intensity of the erase lamps corresponding to a developing bias, the residual image phenomenon can be eliminated while suppressing deterioration of the photosensitive drum to a minimum.

Abstract: An exposure device of an electrophotographic apparatus which includes a rotary polyhedral mirror for scanning a plurality of laser beams on a photosensitive body, a beam interval adjusting member for adjusting an interval between the laser beams, a rotating mechanism for rotating the beam interval adjusting member, and an optical path position deciding device disposed on the side of the rotary polyhedral mirror in a laser beam advancing direction at the time of adjustment of the laser beam interval, the beam interval adjusting member being rotated so that the optical paths of the laser beams are decided by the optical path position deciding device. The optical path position deciding device may include a plate-like member with boresights or a CCD sensor and a CRT display.

Abstract: A developing unit for an electrophotographic apparatus comprises a photosensitive body for forming a latent image thereon, a developing roll utilizing two-component developer containing toner and carrier to develop the latent image formed on the photosensitive body, a recovery roll, provided downstream of the developing roll, for recovering carrier from a surface of the photosensitive body, and at least one recess formed in an inner surface of the developing unit which is confronted with an outer cylindrical surface of the recovery roll, in such a manner that air pressure formed in the recess prevents the developer from scattering out of the developing unit.

Abstract: In a multi-stage roll magnetic brush type of developing device, at least two opposite direction rotation rolls which rotate in an opposite rotation direction to that of a photosensitive body are arranged adjacently and oppositely to a photosensitive body, and at least one same direction rotation developing roll which rotates in the same rotation direction as that of the photosensitive body is arranged adjacently, oppositely to the photosensitive body and upstream of the opposite direction rotation developing rolls in the rotation direction of the photosensitive body. Thus, the path of carrying the developer by the same direction rotation developing roll and the opposite direction rotation developing rolls can be optimized. In the wide area printing at high speed, an image with stabilized printing quality can be obtained without an increase in the production cost.

Abstract: Each of a charging process on and after a second time is carried out by a charging means having a controlling electrode. The relationship between a controlling potential (Vg) applied to the controlling electrode of each charming means, the target surface potential (Vo) of a non-image portion of a surface of a photosensitive body and the direct current component potential (Vdc) of a developing bias potential in each developing process is satisfied by the formula, which is .vertline.Vo.vertline.>.vertline.Vdc.vertline..gtoreq..vertline.Vg.vertlin e.. Thereby the corona current ia supplied to flow sufficiently, it can rise the surface potential of a toner image portion of the surface of the photosensitive body after the re-charming without the excessive rise of the surface potential of the non-image portion of the photosensitive body.