Patent Publication Number: US-9835978-B2

Title: Notched end seal for an electrophotographic image forming device

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application Ser. No. 62/221,799, filed Sep. 22, 2015, entitled “End Seal for an Electrophotographic Image Forming Device,” the content of which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     1. Field of the Disclosure 
     The present disclosure relates generally to image forming devices and more particularly to a notched end seal for an electrophotographic image forming device. 
     2. Description of the Related Art 
     Various seals are used in electrophotographic printers to prevent toner from leaking between the printer&#39;s components. For example, toner leakage may occur from the gaps between a developer roll that supplies toner to a photoconductive drum of the electrophotographic printer, a doctor blade in contact with the developer roll and the housing of a developer unit that holds the developer roll and the doctor blade. Seals may be provided to effectively close the gaps between these components to prevent toner leakage. For example, a J-shaped seal may be used at each axial end of the developer roll to prevent toner from leaking out of the junction between the developer roll, the doctor blade and the housing of the developer unit. 
     The J-shaped seal may include small grooves formed in a helical pattern on a surface of the seal that contacts the developer roll. The grooves are formed between small ribs on the surface of the seal. As the developer roll rotates against the surface of the seal, the grooves direct toner away from the axial ends of the developer roll and back into a toner reservoir in the housing. However, toner may tend to accumulate between the developer roll and the surface of the seal over time due to inefficiencies of the grooves. The accumulated toner may eventually push the seal away from the developer roll creating a toner leakage path past the seal. One approach to the problem of toner accumulation between the developer roll and the seal is to increase the force of the seal against the developer roll in order to resist the seal pushing away from the developer roll. However, the increased force increases the friction between the seal and the developer roll thereby risking damage to the seal, the developer roll and/or the toner due to excessive force or heat. Another approach to the problem of toner accumulation between the developer roll and the seal is to increase the width of the seal in the axial dimension of the developer roll in order to provide added sealing. However, the axial lengths of the developer roll and the doctor blade typically must be increased in order to accommodate the larger seals and maintain the ability to print the desired page width. The longer developer roll and doctor blade may, in turn, increase the overall size of the developer unit contrary to consumer preferences for smaller components. 
     Accordingly, a seal that reduces the occurrence or effect of toner accumulation between the developer roll and the surface of the seal is desired. 
     SUMMARY 
     An end seal for an electrophotographic image forming device according to one example embodiment includes an elastomeric body having a blade seal portion for sealing against a rear surface of a doctor blade and a curved rotary seal portion that extends from a bottom end of the blade seal portion for sealing against an outer surface of a rotatable developer roll. The end seal includes a cutout in an inner axial side of the body positioned at a point where the rotary seal portion and the blade seal portion meet. 
     An end seal for an electrophotographic image forming device according to another example embodiment includes an elastomeric body. The body includes a blade seal portion shaped to seal against a planar rear surface of a doctor blade. The body includes a curved rotary seal portion that extends from a bottom end of the blade seal portion and is shaped to seal against an outer surface of a rotatable developer roll. The end seal includes a cutout through the body at an inner axial side of the body. The cutout is positioned at a bottommost portion of the blade seal portion and a topmost portion of the rotary seal portion such that the bottommost portion of the blade seal portion and the topmost portion of the rotary seal portion have a smaller width across a sealing face of the end seal than a portion of blade seal portion directly above the cutout and a portion of the rotary seal portion directly below the cutout. 
     In some embodiments, a sealing face of the blade seal portion includes a plurality of grooves that run along a longitudinal dimension of the body and a sealing face of the rotary seal portion includes a plurality of grooves that run transverse to the longitudinal dimension of the body. In some embodiments, the cutout has a rectangular cross-sectional shape. In other embodiments, the cutout has a partial circular cross-sectional shape or a triangular cross-sectional shape. In some embodiments, a height of the cutout along a longitudinal dimension of the body is greater than a width of the cutout across a sealing face of the end seal. 
     A developer unit for an electrophotographic image forming device according to one example embodiment includes a housing and a developer roll mounted on the housing. The developer roll is rotatable relative to the housing about an axis of rotation. The developer roll includes an outer surface. A doctor blade is mounted on the housing. The doctor blade is in contact with the outer surface of the developer roll along an axial dimension of the developer roll. The developer unit includes an end seal having a body. The body has a blade seal portion sandwiched between a first interface of the housing and a rear surface of the doctor blade at an end of the doctor blade. The body has a curved rotary seal portion sandwiched between a second interface of the housing and an outer surface of the developer roll at an axial end of the developer roll. The body has an inner axial side and an outer axial side relative to the developer roll. The end seal includes a cutout in the inner axial side of the body. The cutout is positioned at a point where the doctor blade contacts the outer surface of the developer roll. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings incorporated in and forming a part of the specification, illustrate several aspects of the present disclosure, and together with the description serve to explain the principles of the present disclosure. 
         FIG. 1  is a schematic view of an electrophotographic image forming device according to one example embodiment. 
         FIG. 2  is a perspective view of a portion of a developer unit of an electrophotographic image forming device according to one example embodiment. 
         FIG. 3  is a perspective view of the developer unit shown in  FIG. 2  with a developer roll and a doctor blade removed to show an end seal according to one example embodiment. 
         FIG. 4  is a sectional side view of the developer unit shown in  FIGS. 2 and 3 . 
         FIGS. 5A and 5B  are a front perspective view and a rear perspective view, respectively, of the end seal having a cutout according to one example embodiment. 
         FIG. 6  is a front perspective view of a portion of the end seal having a cutout according to a second example embodiment. 
         FIG. 7  is a front perspective view of a portion of the end seal having a cutout according to a third example embodiment. 
         FIG. 8  is an elevation view of the end seal shown in  FIGS. 5A and 5B  schematically illustrating the positions of the developer roll and the doctor blade relative to the end seal according to one example embodiment. 
         FIGS. 9A and 9B  are a front perspective view and a rear perspective view, respectively, of the end seal shown in  FIGS. 5A and 5B  having a foam backing according to one example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, reference is made to the accompanying drawings where like numerals represent like elements. The embodiments are described in sufficient detail to enable those skilled in the art to practice the present disclosure. It is to be understood that other embodiments may be utilized and that process, electrical and mechanical changes, etc., may be made without departing from the scope of the present disclosure. Examples merely typify possible variations. Portions and features of some embodiments may be included in or substituted for those of others. The following description, therefore, is not to be taken in a limiting sense and the scope of the present disclosure is defined only by the appended claims and their equivalents. 
       FIG. 1  illustrates a schematic representation of an example electrophotographic image forming device  100 . Image forming device  100  includes a photoconductive drum  101 , a charge roll  110 , a developer unit  120  and a cleaner unit  130 . The electrophotographic printing process is well known in the art and, therefore, is described briefly herein. During a print operation, charge roll  110  charges the surface of photoconductive drum  101 . The charged surface of photoconductive drum  101  is then selectively exposed to a laser light source  140  to form an electrostatic latent image on photoconductive drum  101  corresponding to the image being printed. Charged toner from developer unit  120  is picked up by the latent image on photoconductive drum  101  creating a toned image. 
     Developer unit  120  includes a toner reservoir  122  having toner particles stored therein and a developer roll  124  that supplies toner from toner reservoir  122  to photoconductive drum  101 . Developer roll  124  is electrically charged and electrostatically attracts the toner particles from toner reservoir  122 . A doctor blade  126  disposed along developer roll  124  provides a substantially uniform layer of toner on developer roll  124  for subsequent transfer to photoconductive drum  101 . As developer roll  124  and photoconductive drum  101  rotate, toner particles are electrostatically transferred from developer roll  124  to the latent image on photoconductive drum  101  forming a toned image on the surface of photoconductive drum  101 . In one embodiment, developer roll  124  and photoconductive drum  101  rotate in opposite rotational directions such that their adjacent surfaces move in the same direction to facilitate the transfer of toner from developer roll  124  to photoconductive drum  101 . A toner adder roll (not shown) may also be provided to supply toner from toner reservoir  122  to developer roll  124 . Further, one or more agitators (not shown) may be provided in toner reservoir  122  to distribute the toner therein and to break up any clumped toner. 
     The toned image is then transferred from photoconductive drum  101  to print media  150  (e.g., paper) either directly by photoconductive drum  101  or indirectly by an intermediate transfer member. A fusing unit (not shown) fuses the toner to print media  150 . A cleaning blade  132  (or cleaning roll) of cleaner unit  130  removes any residual toner adhering to photoconductive drum  101  after the toner is transferred to print media  150 . Waste toner from cleaning blade  132  is held in a waste toner reservoir  134  in cleaning unit  130 . The cleaned surface of photoconductive drum  101  is then ready to be charged again and exposed to laser light source  140  to continue the printing cycle. 
     The components of image forming device  100  are replaceable as desired. For example, in one embodiment, developer unit  120  is housed in a replaceable unit with photoconductive drum  101 , cleaner unit  130  and the main toner supply of image forming device  100 . In another embodiment, developer unit  120  is provided with photoconductive drum  101  and cleaner unit  130  in a first replaceable unit while the main toner supply of image forming device  100  is housed in a second replaceable unit. In another embodiment, developer unit  120  is provided with the main toner supply of image forming device  100  in a first replaceable unit and photoconductive drum  101  and cleaner unit  130  are provided in a second replaceable unit. In another embodiment, developer unit  120  is provided in a first replaceable unit, the main toner supply of image forming device  100  is provided in a second replaceable unit and photoconductive drum  101  and cleaner unit  130  are provided in a third replaceable unit. Further, any other combination of replaceable units may be used as desired. 
       FIG. 2  illustrates an example replaceable unit  200  that includes developer unit  120 . Replaceable unit  200  includes a housing  202  containing developer roll  124  and doctor blade  126  positioned against developer roll  124 .  FIG. 3  shows replaceable unit  200  with developer roll  124  and doctor blade  126  removed to more clearly illustrate the internal components of replaceable unit  200 .  FIG. 3  shows an example end seal  210  positioned in housing  202  at one axial end of developer roll  124 . A second end seal (not shown) is positioned at the opposite axial end of developer roll  124  and may be a mirror image of end seal  210 . A blade seal portion  214  of end seal  210  is compressed between an interface  204  formed in housing  202  and an end portion of doctor blade  126  ( FIG. 2 ). A rotary seal portion  218  of end seal  210  is compressed between a curved interface  208  formed in housing  202  and an axial end portion of developer roll  124  ( FIG. 2 ).  FIG. 4  shows a side view of end seal  210  in housing  202  with a front face or sealing face  220  of end seal  210  positioned against developer roll  124  and doctor blade  126 . As shown in  FIG. 4 , blade seal portion  214  of end seal  210  is positioned against a rear surface of doctor blade  126  and rotary seal portion  218  of end seal  210  is curved around and positioned against a rear surface of developer roll  124 . End seal  210  may be described as J-shaped due to its substantially straight blade seal portion  214  and connecting curved rotary seal portion  218 . End seal  210  prevents toner from leaking at the axial end of developer roll  124  at the interface between housing  202 , developer roll  124  and doctor blade  126 . 
       FIGS. 5A and 5B  show an example end seal  210  in more detail. In some embodiments, end seal  210  includes a molded (e.g., injection molded or compression molded) body  212  made of a polymeric elastomeric material. One suitable example of an elastomeric material is SANTOPRENE™, a thermoplastic vulcanizate available from Exxon Mobil Corporation. In other embodiments, body  212  is composed of foam, felt or the like. End seal  210  includes an outer axial side  230  and an inner axial side  232  relative to developer roll  124 . Sealing face  220  of end seal  210  includes grooves  228  therein to prevent the migration of toner axially outward past end seal  210 . Grooves  228  may be formed between small ribs on sealing face  220  of end seal  210 . Grooves  228   a  on sealing face  220  of rotary seal portion  218  may be angled to guide toner away from the axial end of developer roll  124  as developer roll  124  rotates against rotary seal portion  218 . Grooves  228   a  are open at inner axial side  232  to allow developer roll  124  to push toner through grooves  228   a , off of end seal  210  and back into toner reservoir  122  as developer roll  124  rotates. Grooves  228   b  on blade seal portion  214  may be vertically oriented as illustrated (parallel to a longitudinal dimension of end seal  210 ). 
     End seal  210  includes a notch, indentation or cutout  240  therein on the inner axial side  232  of end seal  210 . End seal  210  is preferably molded to a shape that includes cutout  240  therein when end seal  210  is formed; however, cutout  240  may also be formed by removing the area of cutout  240  from end seal  210  in a secondary operation. Cutout  240  is positioned at a point  216  where blade seal portion  214  and rotary seal portion  218  meet at the inner axial side  232  of end seal  210 . In the embodiment illustrated, cutout  240  is positioned at the bottommost portion of blade seal portion  214  and the topmost portion of rotary seal portion  218  such that the bottommost portion of blade seal portion  214  and the topmost portion of rotary seal portion  218  have a smaller width in the axial dimension of developer roll  124  than the portion of blade seal portion  214  directly above cutout  240  and the portion of rotary seal portion  218  directly below cutout  240 . In some embodiments, cutout  240  is taller than it is wide (i.e., a height of cutout  240  along a longitudinal dimension of end seal  210  is greater than a width of cutout  240  along the axial dimension of developer roll  124 ). In one example embodiment, cutout  240  is 2 mm wide by 4 mm high. In other embodiments, a height of cutout  240  along a longitudinal dimension of end seal  210  is equal to a width of cutout  240  along the axial dimension of developer roll  124 . In other example embodiments, cutout  240  is 4 mm wide by 4 mm high or 2 mm wide by 2 mm high. However, cutout  240  may be narrower, wider, taller or shorter as desired. In the example embodiment illustrated, cutout  240  is rectangular in shape; however, cutout  240  may take any suitable shape (e.g., square, circular, oval, triangular, irregular, etc.). For example,  FIG. 6  shows an end seal  1210  having a circular segment cutout  1240  and  FIG. 7  shows an end seal  2210  having a triangular cutout  2240 . In the embodiment illustrated, cutout  240  extends all the way through the material thickness or depth of end seal  210 . 
       FIG. 8  shows the positions of developer roll  124  and doctor blade  126  relative to end seal  210  schematically illustrated in dashed lines according to one example embodiment. In the embodiment illustrated, cutout  240  is positioned at the point where a free end  128  of doctor blade  126  contacts the outer surface of developer roll  124 . In this embodiment, a bottom segment of doctor blade  126  including free end  128  of doctor blade  126  and a portion of the outer surface of developer roll  124  that free end  128  of doctor blade  126  contacts are positioned in front of end seal  210  in the area of cutout  240 . In the embodiment illustrated, the axial ends of developer roll  124  and doctor blade  126  extend past outer axial side  230  of end seal  210 . 
     During operation, toner may tend to accumulate in grooves  228   a  of rotary seal portion  218  over time as a result of inefficiencies in the sweeping or pushing of toner in grooves  228   a  by developer roll  124  as developer roll  124  rotates. Cutout  240  provides an additional exit path for toner to escape end seal  210  back into toner reservoir  122 . Without cutout  240 , the accumulation of toner may tend to create a stagnation point in grooves  228   a  that prevents developer roll  124  from pushing toner through grooves  228   a  and off of end seal  210 , especially near the point where doctor blade  126  contacts and removes toner from developer roll  124 . Over time, if enough toner builds up, the accumulated toner may push end seal  210  away from developer roll  124  creating a leakage path between end seal  210  and developer roll  124  and/or doctor blade  126 . The additional toner exit path provided by cutout  240  reduces toner stagnation in the area where doctor blade  126  removes toner from developer roll  124 , where the risk of toner stagnation is greatest. This, in turn, reduces the likelihood of end seal  210  pushing away from developer roll  124  thereby improving the sealing performance of end seal  210 . It was found that the sealing performance of end seal  210  improved as the width of cutout  240  along the axial dimension of developer roll  124  increased. However, it is preferred that the width of end seal  210  along the axial dimension of developer roll  124  remain large enough in the area of cutout  240  (e.g., at least 1-2 mm) to maintain the structural stability of end seal  210 . The inclusion of cutout  240  goes against conventional wisdom by effectively reducing the width of end seal  210  in the most critical region of end seal  210 , at the doctor blade  126  and developer roll  124  interface. Typically, the effectiveness of an end seal such as end seal  210  is improved by increasing, rather than decreasing, the width of the seal. 
     In addition to improving the sealing performance of end seal  210 , the inclusion of cutout  240  reduces the material cost of end seal  210 . Further, if instead of including cutout  240 , the width of end seal  210  were increased in the axial dimension of developer roll  124 , the axial lengths of developer roll  124  and doctor blade  126  would also typically need to be increased in order to maintain the same amount of axial space available for toner on the surface of developer roll  124  to maintain the ability to print the desired page width. Increasing the axial lengths of developer roll  124  and doctor blade  126  typically increases the costs of these components. In some instances, increasing the size of developer roll  124  and doctor blade  126  may, in turn, require increasing the size of housing  202 , contrary to consumer preferences for smaller components, which may also increase the cost of housing  202 . Accordingly, the inclusion of cutout  240  may avoid the cost and size increases associated with increasing the width of end seal  210 . 
       FIGS. 9A and 9B  show end seal  210  having a foam backing  250  positioned against rear face  222  of end seal  210 . In the embodiment illustrated, foam backing  250  is positioned against the rear face  222  of both blade seal portion  214  and rotary seal portion  218  of end seal  210 . In some embodiments, foam backing  250  is positioned against rear face  222  of end seal  210  in the area of cutout  240  as illustrated. In other embodiments, foam backing  250  includes a corresponding notch or cutout in the area of cutout  240 . In the embodiment illustrated, foam backing  250  is adhered to rear face  222  of end seal  210 . In other embodiments, foam backing  250  is sandwiched between rear face  222  of end seal  210  and housing  202  and may be adhered to housing  202 . Foam backing  250  biases end seal  210  toward the outer surface of developer roll  124  and the rear side of doctor blade  126  when foam backing  250  is compressed between end seal  210  and housing  202 . The bias applied to end seal  210  by foam backing  250  aids in holding sealing face  220  against developer roll  124  and doctor blade  126  in order to provide sufficient sealing contact of end seal  210  against developer roll  124  and doctor blade  126 . While the example end seal  210  is biased against developer roll  124  and doctor blade  126  by foam backing  250 , it will be appreciated that the bias toward developer roll  124  and doctor blade  126  may be applied by any suitable method. For example, in another embodiment, end seal  210  includes one or more ridges, beams or ribs molded onto rear face  222  that resiliently compress against housing  202  to bias end seal  210  against developer roll  124  and doctor blade  126 . In another embodiment, end seal  210  includes one or more intermediate springs or resilient members that are compressed between rear face  222  of end seal  210  and housing  202  to bias end seal  210  against developer roll  124  and doctor blade  126 . 
     The foregoing description illustrates various aspects and examples of the present disclosure. It is not intended to be exhaustive. Rather, it is chosen to illustrate the principles of the present disclosure and its practical application to enable one of ordinary skill in the art to utilize the present disclosure, including its various modifications that naturally follow. All modifications and variations are contemplated within the scope of the present disclosure as determined by the appended claims. Relatively apparent modifications include combining one or more features of various embodiments with features of other embodiments.