Ricoh Company, Ltd.

Kabushiki Kaisha Ricoh

Tohoku Ricoh Co., Ltd.

Toyoo Okamoto

Seiichi Miyakawa

Kenji Kojima

Akira Midorikawa

Sakae Ota

Keiichi Maruta

Takashi Suzuki

Tatsuo Tani

Akira Saito

Toshio Watanabe

Kenzo Ariyama

Sunao Ikeda

Susumu Tatsumi

Minoru Iwamoto

Kouichi Asakura

Masashi Kuno

Tadashi Yamashita

Tatsuo Tani Formerly Nishikawa

Shigeru Mita

Yoshihiko Kudoh

Youtarou Kakitani

A printer of the present invention includes a chain-delivery type of sheet conveying device arranged in an image transfer region that adjoins image transfer drums. The sheet conveying device includes a pair of drive pulleys, a pair of driven pulleys, a pair of chains each being passed over one drive pulley and one driven pulley, and a clamper affixed to the chains at opposite ends thereof. Each chain has a circumferential length that is an integral multiple of the circumference of an image transfer drum, and a number of teeth that is an integral multiple of the number of teeth of the drive pulley. A stabilizing mechanism is positioned in the image transfer region for preventing the chains from shaking.

Printer and sheet conveying device therefor

An image forming apparatus which forms on a recording paper a visible image in accordance with image data, the forming being performed by using an electrophotographic method, and the apparatus being able to reduce a total recording time spent for recording one page as compared to the present technology. The image forming apparatus comprises a processing unit, comprising a photosensitive drum on which a latent image is formed while the drum is being rotated at a predetermined rotational speed, for processing the image data so as to form the visible image, a conveying unit for conveying the recording paper to/from the processing unit, a driving unit for driving the photosensitive drum and the conveying unit, and a controlling unit for controlling the driving unit so that the rotational speed of the photosensitive drum is changed based on a length of the visible image being formed on said recording paper. A processing time spent on a blank part of the recording paper being reduced by effecting an increase in the rotational speed of the photosensitive drum.

Image forming apparatus having a photosensitive drum rotatable at

An apparatus for cleaning a photosensitive member of an electrostatic copying machine which includes neutralizing means electrically connected to the ground and disposed for contact with the surface of a photosensitive member in a region located between a transfer station where a toner image formed on photosensitive member is transferred onto a transfer sheet and a cleaning station where any residual toner remaining on the photosensitive member after the transfer step is removed. In this manner, the photosensitive member is neutralized after the transfer step before the residual toner is removed therefrom.

Apparatus for cleaning photosensitive member of electrostatic copying

In a reciprocating scan system, movement is stopped for a predetermined length of time between a scan stroke and a return stroke to prevent erroneous imaging of a photoconductive drum (12) which would result in unnecessary loading of a cleaning unit (26) and formation of a partial reversed image in addition to a desired image on a copy sheet (23). Control circuitry (61) may be provided to cause the stopping operation only when the magnification is less than unity or when the length of the copy sheet (23) in the scan direction is longer than the corresponding image length.

Electrostatic copying apparatus

In a bias device for a copying machine, the surface potential of the photo-sensitive member is detected and stored, a bias voltage is obtained by superposing a certain potential on the potential thus stored, the surface potential of an electrode confronting the photo-sensitive member is stored in a non-image period occurring with the photo-sensitive member, and the bias voltage is applied to the electrode in an image development period occurring with the photo-sensitive member, whereby troubles due to the residual voltage of the photo-sensitive member are effectively overcome.

Bias device for a copying machine

A reproduction apparatus (11) including an electrostatic copying machine (12) or the like is operative to produce single copies of a plurality of documents using an automatic document feed device (14) or a plurality of copies of a single document. The copies are discharged onto a sorting device (18); (91); (121); (141) for stacking the copies in either of two positions on a tray (23); (93); (122); (190) thereof. In the automatic feed mode the original documents, after being fed through the automatic feed device (14), are discharged into a discharge unit (19) having a cover (21). If the cover (21) is opened within a predetermined length of time to remove the documents after termination of the copying operation in the automatic feed mode the sorting device (18); (91); (121); (141) is actuated to shift the copies from one position to the other. The same operation is effected in the multiple copy mode if a next copying operation is initiated within the predetermined length of time. The sorting device (91); (121); (141) preferably includes a fixed tray (93); (122); (190) and a movable sheet engaging member (96); (129); (149) which is toggled between two stable positions for shifting the copies to one or the other of the positions on the tray (93); (122); (190). In this manner, the copies are sorted in sets in the automatic feed mode and according to the original documents in the multiple copying mode.

Reproduction apparatus comprising sorting device

In a corona charger for image transfer for use with an electrophotographic copying machine, a corona wire is stretched outwardly curved at the central portion thereof and the curved portion of the corona wire is positioned closer to the central portion of a transfer sheet to which an image is to be transferred, or is positioned so as to apply corona charges first to the central portion of the transfer sheet.

Corona charger for image transfer

An auto-bias developing process for developing an electrostatic latent image formed on a photosensitive member which includes the step of storing a detected potential in order to apply a fixed bias potential to a developing electrode plate wherein the surface potential of a photosensitive member is detected through a developing solution by a sensor electrode, and is stored in a memory circuit for subsequent conversion to a fixed bias potential which corresponds to the detected potential and is applied to the developing electrode. The process also includes the step of removing any toner which attaches to the developing electrode plate, by the application of a reverse bias potential thereto when the developing process is not taking place and the step of rendering the developing electrode plate electrically floating for removing toner from the plate and preventing deposition of toner onto the surface of the photosensitive member.

Auto-bias developing process and an electrophotographic copying machine

A device for detecting toner concentration in a developing solution for developing an electrostatic image includes a casing having a small drainage hole formed at a top portion thereof so that a certain amount of a developing solution will always be present in the casing even when a tank containing a major portion of the developing solution used is made empty for some reason. A lamp and a lightsensitive element are mounted in the casing at locations below the drainage hole so that they may remain submerged in the solution within the casing at all times, thereby to prevent toner particles in the solution from adhering to the active surface of the former and hence errors in the detection due to the adhesion of toner particles. Alternatively, a pair of light transmission members in the form of bundles of optical fibers may be submerged in the solution within the casing, instead of the lamp and element, in order to allow the latter to be disposed externally of the casing.

Device for detecting a toner concentration in a developing solution

A spongy roller is rotated so that the surface thereof is pressed against the surface of a photoconductive drum and moves in the opposite direction therefrom. A resilient blade is also pressed against the photoconductive drum downstream of the roller so as to define a trough therebetween into which is supplied a cleaning liquid. The roller and blade remove all residual toner substance from the drum which remains after development and transfer operations. The cleaning liquid is supplied only while the drum is being operatively rotated in a quantity sufficient to wash away substantially all removed toner substance from between the blade and the drum. The roller is large enough to absorb enough cleaning liquid to remain moist and prevent solidification of removed toner substance between the roller and the drum between copying operations and when the apparatus is shut down.

Drum cleaning system for electrophotographic apparatus

A transfer sheet separator for use with electrophotographic copying machines in which either a toner image or an electrostatic latent image on a photoreceptor drum is transferred to a transfer sheet. A separation roller is arranged near to the drum surface at a separation station for separating the image transferred sheet which inevitably carries residual charge from the drum by electrostatic attraction. To this end, the roller is made from conductive material and either connected to the ground so as to be able to carry the opposite polarity charge than said charge by induction or floated and applied a bias potential of the opposite polarity. Alternatively, the roller is made of dielectric material and charged as well through a rubbing action, for example. With this electrostatic separation means, mechanical means cooperates for practical purposes to ensure such operation.

Transfer sheet separator for use with electrophotographic copying machine

Liquid is applied onto the circumference of a transfer roller by an applicator and thereby onto the circumference of an operating roller. The coefficients of friction in the apparatus are selected so that the transfer roller will be rotated by the operating roller to pick up liquid from the applicator when the thickness of the liquid on the transfer roller is below a selected value, and the transfer roller is prevented from rotating by the applicator when the thickness of the liquid slightly exceeds the selected value so that a uniform liquid film is applied onto the circumference of the operating roller.

Apparatus for forming a uniform liquid film on a roller

An exposure controlling apparatus for electrophotographic copying machines comprises an operating member which is operable externally of the machine to control the amount of exposure. The operating member is normally biased to return to its neutral position, but can be temporarily held in its operative position when operated. The temporary retention is released upon completion of a copying operation, allowing the operating member to return to its neutral position.

Exposure controlling apparatus for electrophotographic copying machine

A squeeze roller retraction assembly for use with electrophotographic copying machines of the type in which a photosensitive drum is removable from the machine, for inspection or other purposes, through an opening formed in a sidewall which opening is normally covered by a coverplate. A squeeze roller which normally engages with the peripheral drum surface has its engagement therewith automatically released once the coverplate has been dismounted from the sidewall, and also is returned to its operative position as the coverplate is remounted, to thereby prevent damage of the drum as well as a wrong usage of the machine which may be caused by forgetting to replace the squeeze roller to the operative position.

Growing community of inventors

Yokohama, Japan

Toyoo Okamoto