International Business Machines Corporation

Lexmark International, Inc.

Stanley Dyer

Ronald Willard Baker

James J Molloy

Donald Fred Croley

Alan E Bohnhoff

Frank Edward Anderson

Michael Craig Leemhuis

Gregory Lawrence Ream

Larry Steven Foster

Donald Wayne Stafford

Benjamin Alan Askren

Christopher Dane Jones

Martin Victor DiGirolamo

Thoi Nguyen

Steven L Applegate

Bernard L Wilzbach

Bruce M Cassidy

Shirish Padmaker Mulay

Donald Lee West

Charles S Aldrich

John Anthony Schmidt

Frank J Horlander

James L Beck

William F Voit, Jr

William Shannon Spencer

Kenneth E Edds

Donald A Walker

John C Bartlett

David M Riherd

An inkjet printer having a printhead closely adjacent a platen and a printzone therebetween has first and second juxtaposed counter-rotating feed rolls for transferring recording media from a first location where a media leading edge is located in an entrance nip between the first and second rolls and a second location where a media trailing edge is located in an exit nip between the first and second rolls. Printer control avoids printing to a media free printzone by sensing for the presence of a sheet of recording media within a nip between the primary and secondary feed rolls and selectively enabling and disabling the printer in accordance with the sensed media presence. The transverse dimension of a sheet of recording media may be estimated by multiple sensors and printer carriage travel limited to less than the estimated dimension.

Printzone media sensor for inkjet printer

A method of controlling a temperature of a print chip of a printhead in an ink jet printer includes providing the printer with a memory device. The print chip is provided with and at least one ink-jetting resistor. The printhead is provided with at least one substrate heater and a heatsink attached to the print chip. Power is applied to the substrate heater and/or the ink-jetting resistor. Temperature data associated with the print chip is recorded during the applying step. A thermal resistance value of the print chip to the heatsink and/or a thermal capacitance value associated with the printhead is calculated dependent upon the recorded temperature data. The thermal resistance value of the print chip to the heatsink and/or the thermal capacitance value associated with the printhead are stored in the memory device. A temperature of the heatsink is measured based upon the thermal resistance value of the print chip to the heatsink, the thermal capacitance value associated with the printhead, a temperature of the print chip, an ambient temperature, and/or a thermal resistance value associated with the heatsink. A level of power to be applied to the substrate heater is set dependent upon the thermal resistance value of the print chip to the heatsink and/or the thermal capacitance value associated with the printhead, and the temperature of the heatsink.

Method and apparatus for thermal control of an ink jet printhead

A computer controlled plain paper printer and image production apparatus comprising a monochromatic, laser stimulated electrophotographic printer having an optionally coupled color ink jet printer is described. The paper medium path from the laser printer is gate controlled between a direct exit path from the laser printer and a color print path into and through the ink jet printer. Both print units produce at their respective capacities and deliver recorded text and images on a paper substrate delivered to one or more discharge trays.

Color highlighting accessory for a monochromatic printer

An interpage gap control, which acts to optimize the throughput of a printer or other device, which utilizes fed pages, monitors the time for a page to be picked and fed to a sensor and the time for the page to pass the sensor. By using these time periods and other constants, the control calculates a delay time from the detection of the leading edge of the page at the sensor. This delay time must expire before the next page may be picked and fed. The control adjusts the delay period by comparing the time periods measured to reference values for the respective periods and if the measured values vary therefrom, adjusts the reference values. The adjustment of the values is made in small increments when the adjustment will tend to narrow the gap width and will replace the reference values with the measured value when the gap must be widened. This insures that the optimum width is approached cautiously, while expanding the gap quickly to avoid a jam condition when the measured time values indicate that the gap has unduly narrowed.

Apparatus for controlling interpage gaps in printers and method of

In an electrophotographic reproduction device, such as a copier or a printer, having a transfer station (17) whereat toner images are sequentially transferred from the surface of a moving photoconductor (10) to the adjacent surface of sheets of moving and spaced transfer material, such as paper, the transfer station is controlled in a manner to produce a substantially similar electrical effect on the photoconductor both when a sheet of transfer material resides in the transfer station intermediate the photoconductor and the transfer station, and when no sheet of transfer material is intermediate the photoconductor and the transfer station.

Transfer station control in an electrophotographic reproduction device

A wear-resistant ribbon guide surface (11 or 25a, 25b) is added to a thermal printhead (1) to lower the ribbon exit angle after printing or to shift the ribbon exit position away from the printing. The angle past that surface remains large enough for visibility of prior printing. The modification of exit conditions makes the printing darker and significantly improves printhead life.

Thermal printhead with ribbon exit guide

Ribbon (22) in thermal printing has an outer layer which adheres to printed characters of intermediate temperatures, lower than printing temperatures. The printhead (7) has a column of electrodes (9) which sweep across the character area. Erase mode selector (16) causes erase of the same character twice, first at a temperature level moderately more than the normal erase level and one at a temperature moderately less than the normal erase level. Erasure in that dual mode is generally effective even for extreme conditions of paper, environment and other influences.

Repetitive mode for thermal printing lift-off correction

Ribbon (22) in thermal printing has an outer layer which adheres to printed characters at intermediate temperatures, lower than printing temperatures. The printhead (7) has a column of electrodes (9) which sweep across the character area. Lift-off is accomplished by the pattern control (40) controlling the current source (38) to provide rapid, square wave pulses displaced in phase 180 degrees at adjoining electrodes (9). The high level of the pulses is about that of the level at printing, and the pulses are sufficiently rapid so that their net effect is to raise the outer layer ribbon (22) to the intermediate temperature. At areas corresponding to underlines of characters, duration of the up period is longer. Good, long term reliability is achieved by the significant erase level being very close to the print level.

Drive for thermal printing lift-off correction

A ribbon feed failure in a printer can cause serious problems, particularly for a printer that uses heat to cause selective ink transfers. Localized heat buildup may injure the printhead and, if allowed to continue, might injure other printer instrumentalities. According to the invention, it is recognized that for ribbons having a degree of electrical conductivity, a mechanical ribbon failure will almost always result in a detectable change of electrical properties. By monitoring the characteristics of an electrical circuit passing through a section of the ribbon around the print point and, preferably, also the printhead-ribbon interface, abnormal electrical parameter values that indicate ribbon failure may be detected to trigger a cessation of printer operation. For a presently preferred implementation in a printer that uses a printhead with multiple electrodes for supplying current to a ribbon, the electrode voltage levels for a plurality of non-adjacent electrodes are combined to provide a resultant voltage level that is examined to detect abnormalities. By so combining voltages, insignificant excursions in electrical characteristics as might result from minor ribbon imperfections are generally eliminated from the triggering of a shutdown response, while still retaining a rapid response for preventing further heat generation in those situations where a serious ribbon failure has occurred.

Electrically conductive ribbon break detector for printers

An electrode drive configuration for a resistive ribbon thermal printer utilizes as a feedback a monitored signal representative of an internal ribbon voltage at the print point. A monitoring contact is preferably located on the opposite side of the printhead from the drive signal return contact and the feedback signal is used to cancel the effects voltage drop variations in the common return portion of the drive signal path.

Drive circuit for thermal printer

For an electro-thermal printer of the kind that uses a ribbon having a central conducting layer that is covered on one surface by a resistive layer that receives electrical printing currents and on the other surface by a thermally transferrable ink layer, printing current is collected from the conducting layer by an electrically conducting contactor at the ink layer surface of the ribbon. Such contact through the ink layer occurs on the takeup side of a printhead where the integrity of the ink layer is not of concern and voids in the ink layer occur as a result of ink transfers for printing. To increase the quality of the electrical connection, projecting points or barbs may be included on said contactor to penetrate to the conducting layer through intact portions of ink layer.

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Lexington, KY, United States of America

Stanley Dyer