Electrophotography – Image formation – Development
Reexamination Certificate
2000-02-23
2001-01-30
Moses, Richard (Department: 2852)
Electrophotography
Image formation
Development
C399S284000, C399S274000, C118S261000
Reexamination Certificate
active
06181904
ABSTRACT:
TECHNICAL FIELD
This invention relates to electrophotographic development and, more particularly, relates to a toner cartridge having an image developer to which toner is delivered with the operative assistance of a toner comminuator.
BACKGROUND OF THE INVENTION
The assignee of this invention has manufactured and sold toner cartridges of two different general designs. For its larger laser printers, the cartridge has contained a pump to meter toner of the kind disclosed in U.S. Pat. Nos. 5,012,289 to Aldrich et al. and 5,101,237 to Molloy, while the external structure of the cartridge is as disclosed in U.S. Pat. No. 5,136,333 to Craft et al. Details of other elements in the cartridge have varied.
For its smaller laser printers, the cartridge is as disclosed in U.S. Pat. No. 5,337,032 to Baker et al., which has a toner hopper extending well below a level having the toner adder roller and which has independent driven systems for the photoconductor roller and for the developer roller system as disclosed in U.S. Pat. No. 5,331,378 to Baker et al.
Further improvements to these cartridges have involved, inter alia, a hopper exit agitator, such as is shown and described in U.S. Pat. No. 5,875,378 to Campbell et al.
To meter the toner that is used to create the electrophotographic image in these smaller laser printers, a doctor blade is positioned to contact the developer roller and create a nip therebetween. The toner is delivered to the doctoring nip for placement on the developer roller. The doctor blade controls the amount of toner that reaches the developer roller by allowing only a thin layer of toner particles through the doctoring nip.
It can be appreciated by those skilled in the art that, in this operation, the toner tends to accumulate behind the doctor blade. The toner becomes packed, interfering with the intended flow thereof to the developer roller. This leads to starvation at the doctoring nip. Furthermore, the packed toner can become fused to the working surface of the doctor blade due to heat and/or pressure caused by the heavy packing of the toner itself. The ultimate result is the emergence of problems with print quality.
There is thus identified a need of preventing the accumulation of toner behind the doctor blade.
SUMMARY OF THE INVENTION
It is thus an object of the present invention to prevent the accumulation of toner behind the doctor blade as it is being delivered to the developer roller.
It is a further object of the present invention to allow a sufficient amount of toner to be delivered to the developer roller to sustain efficient printing.
Another object of the present invention is to provide uniform metering and charging of the toner as it proceeds through the doctoring nip.
It is an additional object of the present invention to prevent an obstruction to the movement of the toner that is rejected by the doctor blade.
It is yet another object of the present invention to prevent the fusion of toner onto the working surface of the doctor blade.
It is still an additional object of the present invention to prevent the doctor blade from losing its conductivity.
Additional objects, advantages and other novel features of the invention are set forth in part in the description that follows and in part are discernable by those skilled in the art upon examination of the following or become apparent with the practice of the invention. The objects and advantages of the invention are realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the foregoing and other objects and in accordance with the purposes of the present invention described herein, a novel toner cartridge having the ability to ameliorate the problems associated with toner accumulation adjacent the doctoring nip is disclosed. In its broadest aspects, the inventive toner cartridge comprises a toner reservoir and a developer in communication with the reservoir and positioned to receive toner therefrom. A common term for the toner reservoir is “hopper” and is used interchangeably herein. A regulator is in operative association with the developer. For purposes of this application, a regulator is defined to mean any device or element to which a flow of toner particles is introduced and which acts to regulate and meter the amount of toner particles delivered to the developer. A comminuator is in operative association with the regulator. For purposes of this application, a comminuator is defined to mean any device or element that acts to separate and break up a packed mass of toner particles.
In the preferred embodiment, the regulator takes the form of a doctor blade. The comminuator acts at a pre-doctoring area, i.e. just in advance of the nip formed by the proximity of the doctor blade and the developer, to prevent the accumulation of toner adjacent to the doctor blade. In accordance with an existing design of cartridges manufactured by the assignee, the inventive cartridge has an exit port associated with the hopper and a development sump downstream from the hopper exit port. A hopper exit agitator is mounted for operation in the transition area from the exit port to the development sump. The hopper exit agitator prevents the buildup of toner in the transition area and development sump.
A particular preferred cartridge design has the comminuator mounted to the hopper exit agitator. This mounting of the comminuator allows it to oscillate with the hopper exit agitator. Incorporating elements from prior art designs, the cartridge also comprises a paddle mounted for rotation within the hopper to contact the hopper exit agitator and cause the oscillating movement of the hopper exit agitator/comminuator assembly.
A preferred embodiment of the comminuator comprises a plurality of spaced blades mounted for movement along a surface of the regulator. Desirably, one of the spaced blades is joined to a next adjacent one of the spaced blades by at least one connecting rib. At least one of the spaced blades is preferably held by a coupler mounted the hopper exit agitator.
In an alternate embodiment, the comminuator comprises a wire that is mounted for movement along a surface of the regulator. Preferably, each end of the wire is received within opposing connectors mounted to the hopper exit agitator.
Still other objects of the present invention will become apparent to those skilled in this art from the following description wherein there is shown and described a preferred embodiment of this invention, simply by way of illustration of a number of the modes best suited to carry out the invention. As will be realized, the invention is capable of other different embodiments and its several details are capable of modification in various, obvious aspects all without departing from the invention. Accordingly, the drawings and descriptions are regarded as illustrative in nature and not as restrictive.
REFERENCES:
patent: 5331378 (1994-07-01), Baker et al.
patent: 5337032 (1994-08-01), Baker et al.
patent: 5875378 (1999-02-01), Campbell et al.
patent: 61-156168 (1986-07-01), None
Burdette Chris Anthony
Calia Jerry Wayne
Campbell Alan Stirling
Janes Todd Lucas
Newman Benjamin Keith
Brady John A.
Lexmark International Inc.
Moses Richard
LandOfFree
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