Patent Application
20110188898
This invention relates in general to a development station for a reproduction apparatus, and more particularly to a movable metering skive for a reproduction apparatus magnetic brush development station, for contamination control at such metering skive.
In typical commercial reproduction apparatus (electrographic copier/duplicators, printers, or the like), a latent image charge pattern is formed on a uniformly charged charge-retentive or photoconductive member having dielectric characteristics (hereinafter referred to as the dielectric support member). Pigmented marking particles are attracted to the latent image charge pattern to develop such image on the dielectric support member. A receiver member, such as a sheet of paper, transparency or other medium, is then brought directly, or indirectly via an intermediate transfer member, into contact with the dielectric support member, and an electric field is applied to transfer the marking particle developed image to the receiver member from the dielectric support member. After transfer, the receiver member bearing the transferred image is transported away from the dielectric support member, and the image is fixed (fused) to the receiver member by heat and/or pressure to form a permanent reproduction thereon.
One type of development station commonly utilized in electrographic reproduction apparatus is the magnetic brush development station, such as shown in U.S. Pat. No. 6,385,415, issued on May 7, 2002, in the names of Hilbert et al. The magnetic brush development station includes a housing providing a reservoir for a supply of developer material. The developer material may be, for example, two-component material including magnetic carrier particles and relatively smaller pigmented marking particles. A mechanism, such as a paddle wheel, auger, or ribbon blender, is located in the reservoir and serves to stir the carrier particles and marking particles to triboelectrically charge the particles so that the marking particles adhere to the surface of the carrier particles. A transport mechanism brings the developer material into the field of a plurality of magnets within a sleeve (commonly referred to as a developer or toning roller). The plurality of magnets and the sleeve are caused to rotate relative to one another such that the magnetic field of the magnets causes the marking particles to be brought into the vicinity of the latent image charge patterns on the dielectric support member. The marking particles are thus applied to the latent image charge patterns in order to adhere to, and thereby develop such patterns.
While magnetic brush development stations of the above-described type are generally suitable for operation in present commercial reproduction apparatus, improvements in speed and range of use escalate the demands on all of the systems of the reproduction apparatus, especially the development station. For example, reliability of the magnetic brush developer station can be affected when marking particles contaminate drive components, seals, and circuit boards. Increased customer and/or service personnel time to clean these components reduces the available up-time and productivity of the equipment. Contaminates are especially disturbing to the magnetic brush developer station performance at the point where developer material is metered onto the developer roller. Metering is necessary to provide a layer of developer material of only that thickness which will serve to optimally develop the image charge pattern on the dielectric support member. Any developer material flow disturbances lead to image quality artifacts in the finished permanent reproduction. Contaminants tend to collect on the metering skive, particularly when the contaminants are larger than the skive spacing from the developer roller. Collected contaminants then impede uniform flow of developer material to the developing zone into association with the dielectric support member, and generate the noted artifacts by, for example, causing incomplete image development. It is therefore desirable to prevent build up of contaminates at the metering skive.
In view of the above, the claimed invention is directed to a magnetic brush development station for a reproduction apparatus. The development station has a housing forming, at least in part, a reservoir for developer material. The development station also has a developer roller mounted within the housing for delivering developer material to a reproduction apparatus dielectric support member in a development zone, the developer roller including a core magnet inside a shell, the core magnet and the shell having relative rotation. The developer station further has a transport mechanism for transporting developer material from the reservoir to the developer roller. The developer station also has a metering skive for establishing a developer material metering gap between the metering skive and the developer roller for controlling the quantity of developer material transported from the reservoir portion of the housing to the developer roller and then through the development zone to develop a latent image charge pattern on the dielectric support member. The developer station also has a mechanism for selectively moving the metering skive to an operative position relative to the developer roller and to a position remote from the developer roller, wherein a build up of contamination at the metering gap between the metering skive and the developer roller can be substantially prevented.
The claimed invention is also directed towards a method of removing a skive blockage from a metering skive in a magnetic brush developer station. A skive movement mechanism is activated. A thumbwheel coupled to a developer roller of the developer station is rotated until the skive blockage appears on the toning shell of the developer roller. The skive blockage is removed.
The claimed invention is further directed towards another magnetic brush development station for a reproduction apparatus. The development station comprises: a) a housing forming, at least in part, a reservoir for developer material; b) a developer roller mounted within the housing for delivering developer material to a reproduction apparatus dielectric support member in a development zone, the developer roller including a core magnet inside a shell, the core magnet and the shell having relative rotation; c) a transport mechanism for transporting developer material from the reservoir to the developer roller; d) a metering skive for establishing a developer material metering gap between the metering skive and the developer roller for controlling the quantity of developer material transported from the reservoir portion of the housing to the developer roller and then through the development zone to develop a latent image charge pattern on the dielectric support member; e) a mechanism for selectively moving the metering skive to an operative position relative to the developer roller and to a position remote from the developer roller, wherein a build up of contamination at the metering gap between the metering skive and the developer roller can be substantially prevented; f) wherein the mechanism for selectively moving the metering skive comprises a side plate slideably coupled to the metering skive; g) wherein the side plate comprises one or more guide pins which slideably engage corresponding one or more bores defined by the metering skive; h) one or more spring elements positioned to bias the metering skive away from the side plate; i) one or more adjustment screws configured to limit a slideable range of motion of the metering skive away from the side plate; j) a pivot plate defining at least one slot; k) at least one skive frame element coupled to the housing and configured to pivotally support the pivot plate; l) at least one activation screw coupled to the metering skive through the at least one slot; m) at least one pivot guide coupled to the at least one skive frame element to support the pivot plate; n) wherein the pivot plate further comprises a pivot axle; o) an actuator coupled to the pivot plate for rotating the pivot plate about a pivot axis; and p) a thumbwheel coupled to the developer roll and configured to enable manual rotation of the developer roll.
The invention, and its objects and advantages, will become more apparent in the detailed description of the preferred embodiment presented below.
It will be appreciated that for purposes of clarity and where deemed appropriate, reference numerals have been repeated in the figures to indicate corresponding features, and that the various elements in the drawings have not necessarily been drawn to scale in order to better show the features.
Referring now to the accompanying drawings,
As described above, the developer material may be composed of two-part material. As such, a plurality of augers 28 is provided, which have suitable mixing paddles for stirring the developer material within the reservoir 12a of the housing 12. A developer roller 14, mounted within the development station housing 12, includes a rotating (counterclockwise in
The quantity of developer material delivered from the reservoir portion of the housing 12, by a transport roller 30, to the developer roller 14, and then to the development zone 20, is controlled by a metering skive 22. The metering skive 22 is positioned parallel to the longitudinal axis of the developer roller 14, at a location upstream in the direction of shell rotation prior to the development zone 20. The metering skive 22 extends the length of the developer roller 14 (see
At each end of the developer roller 14, a single-pole permanent ceramic magnet 24 is used (one end shown in
It is apparent that the magnet 24 as described above therefore provides an effective seal preventing developer material from escaping from the ends of the developer roller 14. Since this seal does not have any moving parts, there is no wear, and there is no mechanical friction, which would generate heat and create undesirable developer material flakes. Moreover, there is no seal material, which would wear and contaminate the developer material.
There have been many different attempts at controlling developer nap thickness on the developer roller 14 as a way to decrease sensitivity to developer roller/dielectric support member spacing. If the developer nap is too thick, developer material can leak away from the magnetic core of the developer roller resulting in contamination of other areas of the electrographic reproduction apparatus. If the developer nap is too thin, there may not be enough developer material present in the developer material transported to the development zone 20 to enable high quality image development. Past attempts at controlling the developer nap thickness on the developer roller (like developer roller 14) have included slots in tubes or plates and metering skives. The slot width or developer material skive metering gap (the distance between the metering skive 22 and the developer roller 14), and its relationship to the developer roller, must be tightly controlled if the developer nap is to be adequately and effectively controlled.
Extreme sensitivity of developer nap height to skive metering gap in prior development stations has been well documented. However, placing the skive metering gap in the region of lowest possible magnetic field from the developer roller's magnetic core 16 decreases that sensitivity by a factor of two to four times. This makes the skive-metering gap easier to setup in manufacturing and less sensitive to differences in the skive-metering gap along the length of the developer roller 14. Still, larger particles in the developer material mixture, and other contaminates, can block the developer material flow at the metering gap between the metering skive 22 and the developer roller 14. This may impede flow of the developer material to the developer roller 14, which in turn can cause artifacts in the development of the image to be reproduced. Therefore, in this embodiment, the metering skive 22 is mounted for selective movement to a first position (shown in
To provide for selective movement of the metering skive 22, as shown in
A plurality of adjusting screws 34 (again, only one is shown in
An actuator mechanism 40 (best seen in
Movement of the slide plate 42, and thus the ramp member 44, is selectively effected by an actuator arm 48. The actuator arm 48 is coupled to a cam member 52 eccentrically mounted on a pin 50. The cam member 52 is received in an opening 54 of a feature 56 extending from the slide plate 42. When the actuator arm 48 is rotated about the axis of the pin 50, the lobe of the cam member 52 engages the walls of the opening 54 and moves the slide plate 42 in the direction parallel to the axis of the developer roller 14. When the slide plate 42 (and ramp member 44) move from the location shown in
During operation of the development station 12, when images are to be developed to form desired reproductions, the lobe of the cam member 52 is set in a location by urging of the spring member 60 in the position to locate the slide plate 42, and thus the metering skive 22, in the first operative position relative to the developer roller 14. This sets the metering gap between the metering skive 22 and the developer roller 14 at the desired predetermined location such that developer material of ideal thickness will be transported through the metering gap to the development zone 20 to optimally develop desired electrostatic images on the dielectric support member DSM.
During non-operative times, the actuator arm 48 may be selectively rotated by any suitable means (manually or mechanically) to position the cam member 52 to set the lobe of the cam member in the position where the metering skive 22 is moved to the second position remote from the first position. In the second position for the metering skive 22, the metering gap between the metering skive 22 and the developer roller 14 is substantially expanded so as to enable any contaminates, which would otherwise disrupt flow in the metering gap, to flow through such expanded gap. The size (weight) of the contaminate particles CP causes such particles to be jettisoned (see
As described above, the developer material may be composed of two-part material. As such, a plurality of augers 28 is provided, which have suitable mixing paddles for stirring the developer material within the reservoir 12a of the housing 12. The developer station 62 also has a developer roller 14, a multi-pole core magnet 16, a shell 18, a development zone 20 between the DSM and the developer roller 14, and a transport roller 30, the features of which have been discussed above with regard to
The metering skive 22 helps to control the thickness of a developer material nap on the developer roller 14. Unfortunately, larger particles in the developer material mixture, as well as other contaminates, can block the developer material flow at the metering gap between the metering skive 22 and the developer roller 14. This may impede flow of the developer material to the developer roller 14, which in turn can cause artifacts in the development of the image to be reproduced. Therefore, the metering skive is configured for selective movement from a first position in operative association with the developer roller 14 illustrated in
Adjustment screws 72 pass through the skive frame element 68, the side plate 66, and a spring element 74 and into the metering skive 22. The spring elements 74 are configured to bias the metering skive 22 away from the side plate 66. Suitable examples of spring elements which may be used include, but are not limited to a leaf spring, a coil spring, and an elastomer grommet. By tightening the adjustment screws 74, the metering skive 22 may be positioned closer to the side plate 66 (farther from the developer roll which is not shown in this view) in an operating position. By loosening the adjustment screws 74, the metering skive 22 may be positioned farther from the side plate 66 (closer to the developer roll which is not shown in this view) in the operating position.
Activation screws 76 pass through slots 78 defined by the pivot plate 70, past the skive frame elements 68, through the side plate 66, and into the metering skive 22. Preferably, the activation screws 76 are not adjusted so tightly that the metering skive 22 is not allowed to travel away from the side plate 66 as far as the adjustment screws 72 are set for. Instead, the activation screws 76 are coupled to the metering skive 22 such that if the activation screws 76 are moved in a direction 80 substantially opposite the metering skive 22, the metering skive will be drawn back towards the side plate 66 when the moving force applied to the activation screws 76 overcomes the opposing force of the spring elements 74. Such a moving force may be supplied by pivoting an actuator such as skive handle 82 in a clockwise direction 84 (other embodiments may use other directions) to rotate the pivot plate 78 coupled to the skive handle 82. Upon rotation 84, the pivot plate 70 pivots on a rotation axis 86, causing the pivot plate slots 78 to engage the activation screws 76 and move them in a backward direction 80. This draws the metering skive 22 against the spring elements 74. When the skive handle 82 is released, the spring elements 74 return the metering skive 22 to its original position. In this embodiment, the skive handle 82 is coupled to the pivot plate 70 via a pivot axle 88 in order to improve the reachability of the skive handle 82. In other embodiments, the skive handle 82 may be directly coupled to the pivot plate 70. The portions of the pivot plate 70 and/or pivot axle 88 which define the rotation axis 86 may be coupled to the skive frame element 68 by pivot guides 90. Additional support brackets 91 may be added as desired.
Similar to the operation of the mechanism of
Although the trend in printing systems is typically advancing towards the automation of machine maintenance, it has been discovered that the above embodiments of metering skives and associated skive movement mechanisms may optionally and advantageously be used in conjunction with a thumbwheel for manually spinning the development roller.
The advantages of a moveable metering skive for a development station of a reproduction apparatus have been discussed herein. Embodiments discussed have been described by way of example in this specification. It will be apparent to those skilled in the art that the foregoing detailed disclosure is intended to be presented by way of example only, and is not limiting. For example, in some embodiments, the metering skive itself could be the mechanism for selectively moving the metering skive to a position remote from the developer roller. In such an embodiment, a user could manually, or through a controllable actuation mechanism, apply force directly to the metering skive to move it to the remote position. Various other alterations, improvements, and modifications will occur and are intended to those skilled in the art, though not expressly stated herein. These alterations, improvements, and modifications are intended to be suggested hereby, and are within the spirit and the scope of the claimed invention. Additionally, the recited order of processing elements or sequences, or the use of numbers, letters, or other designations therefore, is not intended to limit the claims to any order, except as may be specified in the claims. Accordingly, the invention is limited only by the following claims and equivalents thereto.
This application is a divisional of prior U.S. patent application Ser. No. 12/118,903 filed May 12, 2008, which is a continuation-in-part of U.S. patent application Ser. No. 11/512,926, filed Aug. 30, 2006, now U.S. Pat. No. 7,502,581, issued Mar. 10, 2009 each of which is hereby incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12118903 | May 2008 | US |
| Child | 13086648 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11512926 | Aug 2006 | US |
| Child | 12118903 | US |
