Patent Grant
7233760
This invention, according to one embodiment, relates to image forming equipment, including, e.g., copiers, printers, facsimile machines and/or the like. In particular, this invention, according to an embodiment, relates to methods and devices for positioning a doctor blade against a developer roller and may prevent and/or reduce toner loss.
Image forming devices including copiers, laser printers, facsimile machines, and the like, include a photo conductive drum (hereinafter “photoconductor”) having a rigid cylindrical surface that is coated along a defined length of its outer surface. The surface of the photoconductor is typically charged to a uniform electrical potential and then selectively exposed to light in a pattern corresponding to an original image. The areas of the photoconductive surface exposed to light are discharged, thus forming a latent electrostatic image on the photoconductive surface. A developer material, such as toner, having an electrical charge such that the toner is attracted to the photoconductive surface is used for forming the image. The toner is normally stored in a reservoir adjacent to the photoconductor and is transferred to the photoconductor by the developer roll. The thickness of the toner layer on the developer roll may be controlled by a nip, which is typically formed between a doctor blade and the developer roll. A recording sheet, such as a blank sheet of paper, may then be brought into contact with the discharged photoconductive surface and the toner therein is transferred to the recording sheet in the form of the latent electrostatic image. The recording sheet may then be heated thereby permanently fusing the toner to the sheet. In preparation for the next image forming cycle, the photoconductive surface may be discharged and residual toner removed.
As shown in
Typical toner housings may also have a retention post 14 and a retention block 16. Retention posts 14 and retention blocks 16 may function to maintain doctor blade 5 in the proper orientation with the doctor blade lower edge positioned against developer roller 4. The post and block may work in combination and the doctor blade may contact only one or both during the toner transfer process. They may also function to effectively control the positioning of the doctor blade without causing friction with the doctor blade that may restrict the movement of the doctor blade to and from the developer roller. Stop posts, retention posts, and retention blocks may be constructed as a unitary piece having a common back section 18. (See
This invention, according to one embodiment, relates to image forming equipment, including, e.g., copiers, printers, facsimile machines and/or the like. In particular, this invention, according to an embodiment, relates to methods and devices for positioning a doctor blade against a developer roller while, e.g., reducing and/or preventing toner loss.
According to one embodiment of the invention, there may be provided a method for providing toner to an image forming apparatus, said method may have the following steps: applying toner from a reservoir to a developer roller; regulating the amount of toner applied to the developer roller with a doctor blade; and covering the doctor blade with a cover opposite the reservoir to retain toner.
A further embodiment of the invention provides a toner cartridge for an image forming apparatus, the cartridge may have: a housing defining a toner reservoir; a developer roller supported by the housing; a doctor blade supported by the housing and positioned adjacent the developer roller; and a retainer connected to the housing and positioned over a side of the doctor blade opposite the reservoir.
Still another embodiment of the invention, may provide a system for supporting a doctor blade, the system having: a retainer connectable to a toner cartridge housing at a position adjacent to a doctor blade opposite a toner reservoir; and a flange may extend from the retainer and engage the doctor blade.
According to a still further embodiment of the invention, there may be provided a toner cartridge for an image forming apparatus, the cartridge having: a housing defining a toner reservoir; a developer roller supported by the housing; a doctor blade supported by the housing and positioned adjacent to the developer roller; and a means for retaining toner escaping from between the developer roller and the doctor blade.
Some embodiments of the present invention may be better understood by reading the following description of non-limitative embodiments with reference to the attached drawings wherein like parts of each of the several figures are identified by the same referenced characters, and which are briefly described as follows:
It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, as the invention may admit to other equally effective embodiments.
Referring to
In the illustrated embodiment, retainer 10 may also have a cover 15 that may, e.g., extend the entire length of retainer 10 to fully or partially enclose doctor blade 5 and optionally, doctor blade spring 7. Cover 15 may prevent and/or reduce toner from collecting on the external surfaces of the toner unit and may minimize the user's exposure to toner. Retainer 10 may retain doctor blade 5 in housing 2. According to certain embodiments of the present invention, retainer 10 may also retain doctor blade spring 7 in housing 2 with, e.g., a spring cleat 11. According to certain embodiments of the present invention, retainer 10, cover 15, spring cleat 11, stop post 12, retention post 14, and retention block 16 may be formed as a unitary piece. Further, according to certain embodiments of the invention, cover 15 may visually block doctor blade 5 and optionally, doctor blade spring 7 from the user's view, e.g., to provide a more integrated appearance to housing 2. In certain embodiments, cover 15 may only enclose a portion of the doctor blade 5 and/or doctor blade spring 7.
According to an embodiment of the invention, in the middle of retainer 10, a spring cleat 11 may be fixed to cover 15. Spring cleat 11 may engage and may support doctor blade spring 7 and, e.g., push doctor blade spring 7 toward doctor blade 5. If retainer 10 is attached to housing 2, doctor blade spring 7 may be supported by spring cleat 11, e.g., above doctor blade 5 to, e.g., maintain a force to bias a lower edge of doctor blade 5 against developer roller 4. The drawings illustrate doctor blade 5 substantially perpendicular to developer roller 4, however, other orientations may also provide for transfer of desired toner amounts. Doctor blade spring 7 may contact doctor blade 5 at more than one location along the doctor blade 5 to, e.g., ensure that an even and distributed force may be applied across the entire width of developer roller 4.
Retainer 10 may have a plurality of holes 13 through which fasteners may extend to secure retainer 10 to housing 2. In particular, the fasteners may be screws, rivets, guide posts or any other fastener means known to skilled persons. Housing 2 and retainer 10 may be constructed of polystyrene, or any other material known to skilled persons.
According to an embodiment of the invention, dampeners 26 may be provided and may have a damping capacity to absorb vibrations from doctor blade 5. According to one embodiment of the invention, dampeners 26 may be constructed of a resilient material that may be compressed by doctor blade 5 and may apply a force to doctor blade 5. In relation to one embodiment of the invention, dampeners 26 may be constructed of PORON foam, a polyurethane foam commercially available from Rogers Corp. as 4790-92-2008104. According to an embodiment of the invention, only one extension includes a dampener 26.
According to an embodiment of the invention, dampeners 26 may have a thickness such that doctor blade 121 contacts dampeners 26 on a first side and a retention block 16 on the opposite side. According to one embodiment of the invention, dampeners 26 may be about 2.0 mm thick. Dampeners 26 may have a variety of shapes and sizes. According to an embodiment, dampeners 26 may be positioned on the front of the extensions 25 and may rest on a shoulder adjacent to a bottom edge of the extensions 25. According to another embodiment, dampeners 26 may have a width of about 5.0 mm. In one embodiment, dampeners 26 may be attached to extensions 25 by an adhesive that may be applied in a variety of manners. According to an embodiment, the adhesive comprises a pressure sensitive material applied to one side of dampeners 26 facing extensions 25. In relation to one embodiment of the invention, the adhesive may be Model No. 7953 manufactured by 3M. Extensions 25 may include a knurled surface to improve the adhesion of the adhesive.
According to certain embodiments of the invention dampeners 26 may be applied to retention posts 14 and/or retention blocks 16 in addition to being applied to extensions 25 or instead of being applied to extensions 25. Doctor blade 5 may also be squeezed slightly between extensions 25 and retention posts 14 and/or retention blocks 16 by adjusting the positions of the support structures relative to the thickness of doctor blade 5.
Referring to
According to further embodiments of the invention, a uniform structure having a profile shaped like the illustrated flanges may extend across the entire length of retainer 10, e.g., to support doctor blade 5 at all points. As illustrated, each of flanges 19 has a stop post 12, a retention post 14, and a retention block 16. Retainer 10 may also have a spring cleat 11 to, for example, engage doctor blade spring 7. Retainer 10 may be attached to housing 2, and doctor blade spring 7 may reside within spring cleat 11, e.g., so that spring cleat 11 may press doctor blade spring 7 against doctor blade 5.
According to other certain embodiments of the invention, retainer 10 may be attached to housing 2 with, e.g., fasteners, like fasteners 17. Any number of fasteners may be used. The fasteners may extend through holes 13 in cover 15 of retainer 10 and/or through holes 13 in flanges 19. If retainer 10 is attached to housing 2, cover 15 may help reduce or prevent toner from escaping from the toner cartridge 1, e.g., when the toner cartridge is dropped or otherwise mishandled.
Referring to
Referring to
According to certain embodiments of the invention, a seal (not shown) may be positioned where doctor blade 5 contacts the inner side wall of housing 2 and may ensure toner does not leak between these elements and/or substantially reduces the amount of leaked toner. The seal may be a polyester film or O-ring seal; however, other seal materials may also be utilized. A flap seal (not shown) may also extend along the back side of doctor blade 5 and may prevent or reduce the leaking of toner from toner reservoir 6 to developer roller 4, that might ultimately escape the toner cartridge. The flap seal may be positioned against a back edge of doctor blade 5, but may not be attached if the inhibition of the relative mobility of the doctor blade 5 is not desired. The material of the flap seal may provide a low to approximately zero friction contact with doctor blade 5. According to certain embodiments of the invention, the flap seal may be constructed of a polyester film such as that sold under the trademark Mylar by DuPont. However, other low friction materials may also be used.
While the invention has been depicted and described with reference to embodiments of the invention, such a reference does not imply a limitation on the invention, and no such limitation is to be inferred. The invention is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those ordinarily skilled in the pertinent arts having the benefit of this disclosure. The depicted and described embodiments of the invention are examples only, and are not exhaustive of the scope of the invention. Consequently, the invention is intended to be limited only by the scope of the appended claims, giving full cognizance to equivalents in all respects.
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