Patent Application
20120051780
This invention relates in general to an electrophotographic device, and in particular to a method of aligning a photoconductor cartridge in the electrophotographic device.
The electrophotographic process creates an image on paper or other suitable printing media. Various components are assembled into a print engine to enable printing. In order for those components to function correctly they must be mounted within the printer precisely and rigidly. The more precisely components are aligned minimizes correction needed for accurate image placement on paper.
In an electrophotographic device the photoconductor periodically needs to be replaced due to wear, damage, or degradation. The most efficient way to replace a photoconductor is to incorporate it in a cartridge along with some other key components of the electrophotographic device.
There is a need, therefore, to accurately locate a photoreceptive cartridge in a manner which minimizes image registration correction.
Briefly, according to one aspect of the present invention a method for aligning a photoconductor cartridge in an electrophotographic device includes providing at least two holes or at least two pins or a combination thereof in a first end of the cartridge. At least two holes or at least two pins or a combination thereof are provided in a frame of the electrophotographic device which mate with the at least two holes or at least two pins or a combination thereof in the first end of the cartridge when the cartridge is inserted in the electrophotographic device.
The cartridge is inserted into the electrophotographic device and a drive mechanism contacts a spherical bearing of a photoconductor of the cartridge. The photoconductor drives a pair of drive dogs wherein one drive dog is affixed to a spline on the drive mechanism and a second drive dog is affixed to the spherical bearing.
At least one hole or at least one pin is provided in a second end of the cartridge. At least one hole or at least one pin is provided in a frame of the electrophotographic device which mates with the at least one hole or at least one pin in the second end of the cartridge when the cartridge is inserted in the electrophotographic device.
The invention and its objects and advantages will become more apparent in the detailed description of the preferred embodiment presented below.
The present invention will be directed in particular to elements forming part of, or in cooperation more directly with the apparatus in accordance with the present invention. It is to be understood that elements not specifically shown or described may take various forms well known to those skilled in the art.
Referring now to
An imaging module in the printer consists of components to enable printing of a single color image. Multiple modules may be assembled to enable the printing of multiple color images.
Primary charging subsystem 210 uniformly electrostatically charges photoreceptor 206 of photoreceptive member 111, shown in the form of an imaging cylinder. Charging subsystem 210 may include a grid 213 having a selected voltage, or may be in the form of a roller with conductive properties.
Additional necessary components provided for control may be assembled around the various process elements of the respective printing modules. Meter 211 measures the uniform electrostatic charge provided by charging subsystem 210, and meter 212 measures the post-exposure surface potential within a patch area of a latent image formed from time to time in a non-image area on photoreceptor 206.
Image writer 220 is used to expose photoreceptor 206 and may be a light emitting diode (LED) array or other similar mechanisms. Toning unit 225, comprising elements 226 and 227 is used to develop the latent image created by image writer 220 on photoreceptor 206. Cleaning unit 230 removes residual toner from photoreceptor 206 after transfer of the image to a secondary receiver. Other meters and components may be included.
Within the printing module 31, periodic replacement of critical components is necessary to ensure proper function. It may be desirable to cluster multiple components to enable simultaneous replacement.
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The accurate location of the photoreceptive member 111 is critical for registering accurately an image on paper in a printing application. By accurately locating the photoreceptor with respect to the framework, registration correction by other means is eliminated or unnecessary. The hole and slot and pin arrangement serve to exactly locate with respect to the framework 250 the replacement cartridge 200 at both the front and rear of the cartridge. This arrangement is used for a design which is torsionally non-rigid. For designs that are torsionally rigid on either the front or rear of the cartridge one pin is omitted and one slot, so that a total of three pins determine exact location of the replacement cartridge. Further, if the pin constraint pattern is chosen such that the pins are non-coplanar, additional flexural rigidity is obtained in mounting of the cartridge.
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For precise drive control, the shaft 264 which mounts the drive coupling 263 must be accurately centered with tight clearance to the photoreceptive member 111. The use of a drive shaft 264 creates an additional constraint to the replacement cartridge 200 which may cause binding and premature wear.
Two forms of misalignment must be addressed to eliminate this constraint, angular misalignment and positional misalignment of location of the drive. Angular misalignment is addressed through the use of a spherical bushing within the photoreceptor, or a spherical feature 263 on the drive shaft 264. Positional misalignment of the center of the drive shaft and photoreceptor is addressed by designing clearance in the drive support bushing 261 which allow the drive shaft 264 to center on the photoreceptive member 111.
The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the scope of the invention.
