Lexmark International, Inc.

International Business Machines Corporation

James P. Harden

Fred Y. Brandon

Paul D. Horrall

Troy A. Lee

Kermit A. Meece

Kermit Arnold Meece

Christopher David Strack

Alan Stirling Campbell

Troy Dustin Tomson

William Paul Cook

Paul Douglas Horrall

Gregory Lawrence Ream

Larry Steven Foster

Jeffrey Lawrence Tonges

Thomas Steven Taylor

Douglas Anthony Able

Peter E Wallin

James Philip Harden

Fred Young Brandon

Troy A Lee

Ryan David Brockman

Michael Hayes Wilson

Travis Alan Riggs

Christina Allison Cullins

Troy Dustin Smith Tomson

Jared Kuo-Hui Lin

James P Harden

Fred Y Brandon

The present application is directed to methods for transitioning between color printing and black-only printing in an image forming device. A cartridge is moved between a first position in which color printing may occur and a second position in which black-only printing may occur. In the first position, a color developer unit may be in contact with a color photoconductor unit. The color developer unit may be spaced from the color photoconductor unit in the second position. During the transition, a voltage supplied to the cartridge and a speed of a drive motor driving the cartridge may be adjusted.

Methods to control transitions between color printing and black-only printing in an image forming device

The presence of a photoconductor drum in a laser printer may be determined by making electrical measurements without directly sensing drum presence. In some embodiments, this may be done without using any added printer components.

Detecting the presence of a photoconductor drum

Rubber charge roller cores are coated with loose particulate silicon carbide. Excess powder is removed, and the rollers are used in normal operation without an additional outer layer. Consistent, long-life operation of the charge roller is realized.

Coated charge roller

An improved electrophotographic printer is provided in which the voltage applied to the charge roller is automatically adjusted to compensate for its changing characteristics over its life span. A high voltage DC power supply includes an output that is connected to the charge roller, and the input side of this high voltage DC power supply is controlled by a microprocessor of the print engine. The print engine controls the output voltage of the high voltage DC power supply by changing the duty cycle of the pulse-width modulated control signal that is supplied to the input of the high voltage DC power supply. A look-up table contains the correct duty cycle for the pulse-width modulated control signal with respect to the number of prints that have been made. The result of the inspection of the look-up table is used by the microprocessor of the print engine to control the correct duty cycle for the pulse-width modulated signal. Over time, the charge roller characteristics begin to change, and after a predetermined number of prints have been made, the pulse-width modulated control signal has its duty cycle increased by a value that is provided in the look-up table. This increase in the duty cycle is performed several times over the operating life of the charge roller, in order to maintain the effective voltage applied to the photoconductive drum to a nominal value.

Method and apparatus for automatically compensating a degradation of the

A flexible doctor blade having a radiused surface or nub for contacting a developer roll. The blade geometry which includes a cantilevered support for the nub provides lower torque in the developer, compliance to compensate for developer imperfections, and less tendency for streaking due to toner packing and filming.

Flexible doctor blade having a radiused contact surface

A toner cartridge (1) has a cylindrical toner hopper (61) with a rear wall (61a) defining an output opening well above the lower part of the hopper. A paddle (63) is rotated in the hopper. The exit surface (61aaa) declines downward to form a chamber for the toner adder roller (45) and developer roller (43). This configuration discourages toner from returning to the hopper after it has been electrically charged. To improve movement of toner past the opening an agitator bar (65) extends across the cartridge near the exit surface. The bar is pivoted at both ends and has a portion (65a) which extends into the path of the paddle. As the paddle rotates, it moves the agitator upward until the curved paths of the two members reach separation, at which time the bar drops by gravity. The bar jars toner loose and eliminates jams of toner. The flat surface of the bar, when it has been moved up, partially blocks the exit opening, which desirably limits toner flow.

Toner cartridge with hopper exit agitator

A printing machine includes a charge neutralizing system for neutralizing static charge on sheets of material fed therethrough. The charge neutralizing system includes a grounded wire (47) located in proximity to the sheets for neutralizing charge on the sheets. The charge neutralizing system further includes a grounded conductive brush (81) mounted on a sheet deflector (61) so that one end of the brush (77) contacts sheets as they traverse a first sheet feed path (71) and the other end of the brush (79) contacts sheets are they are routed by the deflector to a second alternative sheet feed path (63). The grounded brush (81) further serves to decelerate the sheet as it exits the printing machine over the second sheet feed path (63).

Printing machine with charge neutralizing system

A pressurized ink jet stream is broken up into droplets spaced substantially uniform distances by application of a predetermined frequency to the stream. When the velocity of the stream is to be determined, a frequency perturbation is placed in the predetermined frequency to produce a gap in the stream of droplets at a selected distance from the perturbation application point. The presence of the gap is optically sensed at the selected distance by determining when the time period between adjacent droplets at the selected distance exceeds a predetermined period of time. The velocity of the stream is determined in accordance with the time that it takes from the perturbation of the gap until the gap is sensed at the selected distance because of the time period between adjacent droplets exceeding the predetermined period of time. After the velocity of the stream is determined, it is compared with a desired velocity, and corrections in the pressure of the stream are made in accordance with the difference between the determined velocity and the desired velocity and whether the determined velocity is larger or smaller than the desired velocity so that the velocity of the stream can be corrected to be within a predetermined range of the desired velocity.

Method and apparatus for determining the velocity of a liquid stream of

The application of the voltage on a charge electrode to selectively charge droplets of a pressurized conductive ink stream is synchronized with the break off of the droplets from the stream so that the break off occurs in the third quarter of the time period during which the charge voltage is placed on the charge electrode. To determine in which quarter that break off is occurring, the charge voltage is placed on the charge electrode at the same time for two adjacent quarters of a cycle during each of the two adjacent cycles in which a disturbance is placed on the stream by drive means such as a transducer, for example, to produce two droplets. During the next application of the charge voltage on the charge electrode, the charge voltage is applied for the last of the prior two adjacent quarters and the next adjacent quarter during two adjacent droplet producing cycles. During the third application of the charge voltage on a charge electrode, the voltage is placed on the charge electrode for the last of the prior two adjacent quarters of the second application and the next adjacent quarter during each of two adjacent droplet producing cycles. The final periodic application results in the charge being placed on the charge electrode during the last of the prior two adjacent quarters of the third application and the next adjacent quarter during each of two adjacent droplet producing cycles. When the charge voltage is applied to the charge electrode at the time of break off, an optical sensor, which is disposed a predetermined distance downstream from the charge electrode, senses a gap between the two charged droplets because they will have repelled each other. This enables determination of the location of the break-off point of the stream with respect to when the charge voltage is placed on the charge electrode so that there can be synchronization between when the charge voltage is applied to the charge electrode and the break-off point of the droplets from the stream.

Method and apparatus for synchronizing charging of droplets of a

Growing community of inventors

Lexington, KY, United States of America

Kermit Arnold Meece