Electrophotography – Image formation – Development
Reexamination Certificate
1999-08-10
2001-03-27
Pendegrass, Joan (Department: 2852)
Electrophotography
Image formation
Development
C222SDIG001
Reexamination Certificate
active
06208823
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates, generally to a printer or copier toner station and in particular to a developer station with a cross-conveyance means and a dosing means which is supplied by an intermediate receptacle, whereby a toner box opens into the intermediate receptacle at a first end of the receptacle, and toner in the intermediate receptacle is conveyed via a conveyance path across the entire printing width from the first end of the intermediate receptacle to a second end in a direction of conveyance transverse to the direction of displacement of a carrier material that is provided with toner, and, dosed by of the dosing means, the toner is released onto the carrier material.
2. Description of the Related Art
In high-speed printers which print over 10 pages per minute, developer stations which process a mixture of toner and carrier particles are usually used. While the toner is conveyed onto the material to be printed, the carrier particles remain in the developer station. In these developer stations, it is necessary to feed fresh toner to the developer mixture during the print operation. This type of developer station with toner dosing is described in U.S. Pat. No. 4,935,783, for example.
In developer stations with integrated toner cross-conveyance and toner dosing, care must be taken in the cross-conveyance of the toner to enable a uniform feeding of toner over the entire printing width of the carrier material that is to be supplied with toner. Since the different toner types differ in their transport behavior, particularly in the ratio of the toner cross-conveyance amount and the toner dosing amount, complications can arise in the toner feed in a developer station with specified conveying means and dosing means. Namely, a strong setting of the toner on the toner conveyance path, or on the other hand a toner depletion, can arise on the conveyance path, which extends over the entire printing width. Both a toner compacting of the and a toner depletion result in flaws in the printed image. A multiple toner compacting leads to toner contamination due to toner lumps, a toner depletion leads to an uneven coloration of the carrier material.
The Japanese patent document reference JP 59-100472 A teaches a means for the cross-conveyance of toner. Japanese patent document JP 4-365073 A teaches a developer station in which the ratio between the rotation speed of a developer drum and the toner conveyance speed in a toner transport means can be modified.
SUMMARY OF THE INVENTION
The present invention is based on the object of avoiding a toner compacting or a toner depletion during the toner feed in a developer station with cross-conveyance and of achieving a relatively constant ratio of the toner cross-conveyance amount and toner dosing.
This and other objects are achieved by a developer station of the abovementioned type, wherein the ratio between the amount of toner that is conveyed in the transverse direction per unit of time and the amount of toner that is released in a dosed manner per unit of time can be adjusted. A toner distribution is thereby generated in the intermediate receptacle for the toner cross-conveyance in which the amount of toner diminishes from the beginning of the toner conveyance path to the end of the toner conveyance path, and a toner compacting or toner depletion is avoided. The adjustment can occur by means of a mechanical interactive connection between elements for the cross-conveyance and elements for the dosing or by a corresponding electronic controlling of corresponding elements.
In a preferred exemplifying embodiment of the invention, the cross-conveyance means is so designed that the cross-conveyance speed of the toner decreases over the conveyance path extending from the toner box in the transverse direction. This reduces the danger of a toner backup in the frontal region of the intermediate receptacle and the danger of a toner depletion in the rear region of the intermediate receptacle.
A toner distribution is thus generated in the intermediate receptacle for the toner cross-conveyance wherein the amount of toner diminishes from the start of the toner conveyance path to the end of the toner conveyance path, and a toner compacting or toner depletion is prevented, while the danger of a toner backup in the frontal region of the intermediate receptacle and the danger of a toner depletion in the rear region of the intermediate receptacle are simultaneously reduced.
The cross-conveyance means is preferably a toner conveyor helix which is driven by a driver, and the dosing means is preferably a toner dosing shaft which is driven by a connecting rod, whereby the cross-conveyance means and the dosing means are coupled with one another via a driver lever arm and a joint in particular.
In another preferred development, the cross-conveyance means is implemented as a toner conveyor helix which is driven by a driver and whose pitch decreases over the conveyance path, which extends transversely from the toner box. Alternatively, the toner conveyance helix can be fashioned such that its thickness decreases over the conveyance path, which extends transversely from the toner box. As the distance from the first end, i.e. from the front part of the intermediate receptacle, increases, the conveying power of the toner conveyor helix toward the other end, i.e. to the rear part of the intermediate receptacle, decreases.
In another preferred development of the invention, the cross-conveyance means is a toner conveyance helix which is driven by a driver, the pitch and/or thickness of which helix decreases over the conveyance path extending transversely from the toner box. This enables even more constructional freedom in the designing of the toner conveyor helix and even greater reliability in the transverse transport of the toner.
In one specific development, the cross-conveyance means is a toner conveyance helix that is driven by a driver, and the dosing means is a toner dosing shaft that is driven by a connecting rod, whereby the cross-conveyance means and the dosing means are coupled with one another via a driver lever arm and a joint, in particular. This mechanical driving of the toner conveyance helix and the dosing means is uncomplicated and enables their simple mechanical coupling.
The ratio of the amount of toner that is conveyed transversely per unit of time and the amount of toner that is released in a dosed manner per unit of time can be advantageously adjusted by means of an adjustable lever arm length of the driver lever arm and/or an adjustable eccentric lift of the connecting rod. The ratio between the toner cross-conveyance amount and the toner dosing amount can thereby be held constant regardless of the toner type, in order to guarantee a uniform toner feed over the entire printing width. The lever arm length and/or the eccentric lift can be adjustable in a stepped or stepless manner, as required.
REFERENCES:
patent: 3180313 (1965-04-01), Eisner
patent: 4558659 (1985-12-01), Alden
patent: 4935783 (1990-06-01), Fujisawa
patent: 5139176 (1992-08-01), Reindl et al.
patent: 5345298 (1994-09-01), Corrigan, Jr.
patent: 32 25 870 (1984-01-01), None
patent: 0 374 920 (1990-06-01), None
patent: 0 652 493 (1995-05-01), None
patent: 59-100472 (1984-06-01), None
patent: WO 89/08284 (1989-09-01), None
Japanese Abstract, 59-100472, Jun. 9, 1984.
Japanese Abstract, 4-365073, Dec. 17, 1992.
Hill & Simpson
Oce' Printing Systems GmbH
Pendegrass Joan
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