Eastman-kodak Company

Nexpress Solutions, Inc.

Frank A Shuster

Arthur S Kroll

David McLaughlin Rakov

Timothy Gilbert Armstrong

Francisco Luiz Ziegelmuller

Graham S Wright

A module, included in an electrophotographic printer, for making toner images by a method in which transfer current for electrostatic transfer of toner images to receiver members is adjusted to compensate for ambient variations of toner charge-to-mass ratio (q/m). A predetermined functional relationship between transfer current and a control voltage parameter is utilized. Magnitudes of the control voltage parameter are derived from voltage measurements relating to creation of toner control patches on a photoconductive image-recording member included in a modular electrophotographic printer. Control voltage magnitude is linearly dependent on q/m. The functional relationship, which is characterized by three experimentally determined parameters, is co-optimized for providing efficient transfer of toner images and for minimizing back-transfer of toner away from a receiver member in a transfer station included in the module.

Toner transfer technique

An electrostatographic machine having a transfer station including a toner image carrier and a transfer member for electrostatic transfer of toner from the toner image carrier to a toner-image area on a receiver sheet in a nip formed between the toner image carrier and the transfer member. Receiver sheet has a leading edge included in a leading edge margin area and a trailing edge included in a trailing edge margin area. A programmable power supply supplies and controls transfer station current. Before the leading edge enters the nip and after the trailing edge leaves the nip, but not while the toner-image area is in the nip, transfer station current is successively switchably altered by the programmable power supply between at least two predetermined magnitudes. The transfer station current is preferably zero, of a low magnitude, in at least a portion of the leading edge margin area so as to effectively suppress wrap.

Transfer of toner using a time-varying transfer station current

A series of toner images are formed on an endless belt having a splice. The toner images are transferred to a receiving sheet which is fed between the belt and a rotatable transfer member. The transfer member is cleaned by transferring toner back to the belt. Excess toner transfer from the splice of the belt to the transfer roller is obviated by either making the transfer member of a size that the toner will transfer back at an interframe area or applying a lacquer or other similar material to this splice to prevent the pickup of toner initially.

Cleaning mechanism for transfer member

Disclosed is apparatus for scavenging charged particles (e.g. triboelectrically carrier particles) from an electrographic recording element. Such apparatus comprises a conductive grid positioned in close proximity to the path of the recording element, and biasing means for electrically biasing the grid so as to attract the charged particles from the recording element yet prevent them from depositing on, and thereby contaminating, the grid.

Biased scavenging grid for electrographic apparatus

Contrast and/or density adjustment of developed electrographic images is effected in a development system comprising a hard magnetic carrier and a magnetic brush having a rotary core and shell. The adjustment is effected by cooperatively varying the core and shell rotation rates, within predetermined ranges, in a manner which maintains the operative developer linear velocity generally equal to, and co-current with, the velocity of an electrographic image member's movement through the development zone.

Electrographic apparatus, method and system employing image development

Improved electrographic development apparatus and procedure for use with partially-conductive developer employs transport of the developer through a first development zone in a direction generally countercurrent to a moving image member and through a second development zone in a direction generally co-current to the moving image member. The extent of image development within each such zone is controlled by the rate of developer transport and/or the magnitude of developer bias, so that overall development of the different portions of large solid image areas (particularly leading and trailing portions of such areas) is equalized.

Electrographic development apparatus and method for use with

Improved electrographic development apparatus and procedure for use with partially-conductive developer employs transport of the developer through a first development zone in a direction generally countercurrent to a moving image member and through a second development zone in a direction generally cocurrent to the moving image member. The extent of image development within each such zone is controlled by the rate of developer transport and/or the magnitude of developer bias, so that overall development of the different portions of large solid image areas (particularly leading and trailing portions of such areas) is equalized.

Electrographic development apparatus

A device for applying single component developer includes an electrically conductive fur brush which charges the toner triboelectrically and which serves as a donor roller to a touchdown applicator roller. Electrical metering means control the supply of toner to the applicator and to the image member to be developed to facilitate more uniform image development.

Single component developer applicator apparatus

An electrographic apparatus, of the type employing a brush-type developer applicator which contacts one side of a flexible electrostatic image-bearing web, has (1) a web feed-path constructed in a predetermined configuration and (2) the applicator predeterminedly positioned relative to the feed-path defining elements, such that the flexible image-bearing web is allowed to move freely toward and away from the developer applicator in response to the varying contours of the applicator.

Growing community of inventors

Rochester, NY, United States of America

Frank A Shuster