Electrophotography – Image formation – Transfer
Reexamination Certificate
2002-05-13
2004-04-13
Chen, Sophia S. (Department: 2852)
Electrophotography
Image formation
Transfer
C198S807000, C399S165000, C399S301000
Reexamination Certificate
active
06721528
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a method and a controller for regulating the position of a band-shaped intermediate image carrier in an electrographic device. Such band-shaped intermediate image carriers are usually deflected via rollers. Since, due to manufacture, fluctuations in the roller geometries, fluctuations in their relative position with respect to one another and fluctuations in the band geometries cannot, however, be avoided, an intermediate carrier that is transported in unregulated fashion would drift out of its rated track transversely relative to the transport direction.
2. Description of the Related Art
Such an intermediate image carrier and such an electrographic printer device are disclosed, for example, by U.S. Pat. No. 4,061,222.
The intermediate carrier is an endless band that is conducted over a plurality of deflection rollers. The band comprises a light-sensitive, photoconductive layer on which an image can be generated with optical signals. The image is then inked with toner in a developer station in conformity with the optically applied information, and the image is transfer printed onto a recording medium at a transfer printing station.
The lateral position of the photoconductor band is regulated in the known printer device. To that end, a sensor is provided that acquires, or senses, a lateral edge of the photoconductor band. A motor operator for tilting a deflection roller is driven with the position signals and, thus, a control circuit is formed for the position of the band edge.
When the lateral position of the photoconductor band is regulated in that the actual position of the lateral band edge is monitored, then the regulated running track follows irregularities of the band edge. Dependent on the quality of the band edge, this leads to an unsteady and, thus, unfavorable running behavior of the band.
U.S. Pat. No. 4,959,040 likewise discloses a method and an apparatus for regulating the lateral position of a photoconductor band. Deviations of the band position from a rated track are thereby continuously corrected in that one of the rollers over which the band runs is tilted in a regulating process. In this system, disturbing quantities that are caused by irregularities of the band edge are compensated. It is thereby provided to durably apply marks onto the band at defined intervals over the entire circumference of the photoconductor band along a band edge. The band contour is determined in a measuring process in that an actuator of the track regulation, namely the tiltable deflection roller, is set or, respectively, tilted such that the band runs toward one side onto its rated position or, respectively, track. Over a complete band revolution, the applied marks are then acquired with a sensor, and the marked positions are stored as X-positions of the band. The lateral position of an edge of the band is sensed with a second sensor at every X-position. The Y-value that is thereby obtained is stored in a table as a value pair together with the appertaining X-value. The most recently stored X-value of the value pairs corresponds to the same position mark on the photoconductor band as the first X-value. Consequently, the difference between the first Y-value and the last Y-value corresponds to the amount that the band has run laterally off within the one revolution. The identified Y-values are then corrected by means of linear regression. The numerical table acquired in this way reflects the actual shape of the band edge. Every marked X-position of the band thus has a Y-rated value unambiguously allocated to it via the stored table values.
Irregularities in the sampled band mark can be compensated with the above-described method, and a relatively high track precision given quiet band running can be achieved. Since the respective course of the band edge is stored as a reference, greater tolerances in the band edge can be left standing then giving methods that do not acquire the band edge. What is disadvantageous in this method is that the precision of the acquired band contour is prescribed by the resolution of the mark supplied on the band. When one wishes to achieve a high resolution, then high-resolution marks are necessary, these in turn requiring a relatively great technical outlay.
European Patent Document EP-B1-608 124 discloses a method and an apparatus wherein the lateral position of a photoconductor band in an electrophotographic printer device is controlled with a control coefficient. The lateral excursions of the photoconductor band are thereby determined in a measuring process, these deriving when a deflection motor that acts on a deflection roller that deflects the band is moved in two opposite directions in succession by a specific number of steps proceeding from an initial position. A control coefficient is then identified from the measured excursions. For acquiring the band edge position, a plurality of notches are provided in the photoconductor band that form a Z-like shape. These notches are acquired with a transmitted light sensor. The deflection roller can implement both a swivel motion for varying the lateral band position as well as a linear motion along the band running direction for minimizing friction during the swivel motion. European Patent Document EP-A-785 480 discloses a further device for regulating the lateral position of an endless band in an electrophotographic printer device. Given this apparatus, the band is conducted over a deflection roller that, on the one hand, is tilted for regulating the lateral band position and, on the other hand, is connected to a drive motor for the band drive.
Further methods and devices for regulating the band velocity or, respectively, the band edge of endless bands are disclosed by U.S. Pat. No. 5,096,044, by U.S. Pat. No. 5,225,877, by Japanese Patent Document JP-A-10-139202, by European Patent Document EP-A1-619 528 and by U.S. Pat. No. 5,248,027. Another electrographic printer device is disclosed by Published PCT application WO-A-98/39691. Given this printer device, a latent image is generated on a photoconductor band, the image is then developed and transferred onto a transfer band. From this transfer band, finally, the image is transfer printed onto the recording medium, for example onto paper. Given this device, too, it is necessary that the lateral positions of the intermediate image carrier, particularly of the photoconductor band but also of the transfer band, are adhered to as exactly as possible. Published PCT Application WO-A-98/27472 discloses an electrographic printer having at least two developer units.
U.S. Pat. No. 5,515,139 discloses a sensor for sensing a band edge, whereby a mechanical sensing lever runs along at the band edge.
European Patent Document EP-A-0 679 018 discloses a method for regulating the lateral position of a band-shaped intermediate carrier, whereby the lateral positions of the edge profile are acquired as prescribed longitudinal positions in a revolution of the band and the lateral positions are stored together with the longitudinal positions. The lateral positions are averaged to average values in a plurality of successive revolutions of the band. In the regulating process, the difference between the actual value of the lateral position at the respective longitudinal positions and the appertaining average is formed in a revolution of the band. Dependent on this difference, the band is modified in its lateral guidance. Subsequently, a new average is formed in the fashion of a sliding average from the actual value of the lateral position and the appertaining average.
The documents EP-A-0 494 105, U.S. Pat. No. 5,903,805, JP-A-60057040 disclose methods wherein the lateral position of a band is influenced dependent on measured signals of a sensor that detects the edge of the band.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method and a system with which the lateral position of a band-shaped intermediate image carrier can be adhered to as exactly as possible in
Ferber Otto
Hintler Franz
Reihl Heiner
Scherdel Stefan
Schreieder Josef
Chen Sophia S.
Oce Printing Systems GmbH
Schiff & Hardin LLP
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