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1. Field of the Invention
The present invention relates to a doctor blade assembly, and more specifically relates to an upper seal for a doctor blade assembly which inhibits toner leakage generally in the area of the developer housing and the doctor blade bracket assembly.
2. Description of the Related Art
Laser printers utilize a light beam which is focused to expose a discreet portion of a photoreceptive or image transfer drum in a further attempt to attract printing toner to these discreet portions. One component of a laser printer is the photoreceptive drum assembly. This photoreceptive drum assembly is made out of highly photoconductive material that is discharged by light photons typically embodied by a laser. Initially, the drum is given a charge by a charge roller. As the photoreceptive drum revolves, the printer shines a laser beam across the surface to discharge certain points. In this way, the laser “draws” the letters and images to be printed as a pattern of electrical charges—an electrostatic latent image. The system can also work with either a more positively charged electrostatic latent image on more negatively charged background or a more negative charged electrostatic latent image on a more positively charge background.
The printer's laser or laser scanning assembly draws the image to be printed on the photoreceptive drum. The traditional laser scanning assembly may include a laser, a movable mirror and a lens. The laser receives the image data defined by pixels that make up the text and images one horizontal line at a time. As the beam moves across the drum, the laser emits a pulse of light for every pixel to be printed. Typically, the laser doesn't actually move the beam. Instead, the laser reflects the light beam off of a movable mirror. As the mirror moves, the light beam passes through a series of lenses. This system compensates for the image distortion caused by the varying distance between the mirror and points along the drum. The laser assembly moves in one plane horizontally as the photoreceptor drum continuously rotates so the laser assembly can draw the next line. A print controller synchronizes this activity. The process of forming the light image on the photoreceptive drum discharges those areas where the image is formed.
When the toner becomes electrostatically charged, the toner is attracted to exposed portions of the image transfer drum. After the data image pattern is set, charged toner is supplied to the photoconductive drum. Because of the charge differential, the toner is attracted to and clings to the discharged areas of the drum, but not to the similarly charged “background” portions of the photoconductive drum. Toner is an electrostatically charged powder with two main ingredients, pigment and plastic. The pigment provides the coloring, such as black in a monochrome printer to form text and images. This pigment is blended with plastic particles, so the toner will melt when passing through the heat of a fuser assembly. The toner is stored in the toner cartridge housing, a small container built into a removable casing. The printer gathers the toner from a sump within the housing and supplies it to a developer unit using paddles and transfer rollers. The developer roll is a charged rotating roller, typically with a conductive metal shaft and an polymeric conductive coating, which receives toner from a toner adder roll position adjacent the developer roll. Due to electrical charge and mechanical scrubbing, the developer roll collects toner particles from the toner adder roll. A doctor blade assembly engages the developer roll to provide a consistent coating of toner along the length and surface of developer roll, by scraping or “doctoring” excess toner from the developer roll. The doctor blade may also induce a charge on the toner. In turn, this provides a consistent supply of toner to the photoconductive drum. When the coating of toner on the developer roll is inconsistent, too thick, too thin or bare, coating of the photoconductive drum is inconsistent and the level of darkness of the printed image may vary unintentionally, which is considered a print defect.
The electrostatic image on the photoconductive drum is charged such that the toner particles move from the developer roll onto the latent image on photoconductive drum. With the image data toner pattern on the photoconductive drum, the drum engages a sheet of paper or media moving adjacent thereto. The paper or other media is driven by a transport belt, which is oppositely charged to the toner causing it to transfer to the paper or other media. This charge is stronger than the charge of the electrostatic image, so the paper can pull the toner powder away from the surface of the photoconductive drum. When a medium, printing paper, passes beneath the rotating photoconductive drum, the toner is transferred to the medium. Since it is moving at the same speed as the drum, the paper picks up the image pattern exactly. To keep the paper from clinging to the drum, it can be discharged immediately after picking up the toner.
One problem with existing doctor blade assemblies is that of providing a consistent seal generally around the location where doctor blade assembly and the developer housing meet due to the tolerances and stiffness of the seal utilized in this location. Additionally, as shown in the prior art device depicted in
It would be desirable to inhibit toner leakage in the area of the corner of the developer housing as well as the corner where the bracket and blade meet without adding additional parts or increasing expense through additional components to seal this area.
A seal, for inhibiting toner leakage from a toner cartridge having a doctor blade assembly having a doctor blade seal and a developer roll, comprises an upper seat portion for sealably engaging said doctor blade assembly and a leg for sealably engaging said developer roll. The upper seat portion comprises an upper seat inner seal wall and an upper seat outer seal wall spaced apart from said upper seat inner seal wall a preselected distance and defining a gap therebetween for closely receiving a portion of the doctor blade seal between said upper seat inner and outer seal walls. In a further embodiment, the upper seat inner seal wall is disposed at a substantially acute angle respect to said upper seat outer seal wall and in another embodiment, the upper seat outer seal wall comprises an upper tapered horizontal edge and a curved vertical edge.
A seal assembly for inhibiting toner leakage comprises a j-seal positioned to be received by a developer housing. The j-seal has an upper seat portion forming a doctor blade seal and a leg for slidably sealing a developer roll. The upper seat portion has an upper seat inner seal wall and an upper seat outer seal wall spaced apart a preselected distance and defining a gap. The doctor blade seal engages the upper seat inner and outer seals. A doctor blade bracket assembly is disposed adjacent the j-seal and the doctor blade seal, the doctor blade seal further having a tongue disposed within the gap defined between the upper seat inner and outer seal walls, the doctor blade seal sealably engaging the doctor blade bracket assembly. The seal assembly further comprises a curved upper edge of the upper seat outer seal. The seal assembly further comprises having the upper seat inner seal angled to receive an angled surface of the doctor blade seal. The doctor blade bracket assembly compresses the doctor blade seal within the upper seat portion of the j-seal. The doctor blade bracket assembly engages an upper curved or tapered edge of the upper outer seat seal to provide an inwardly directed component force on the upper seat outer seat. The doctor blade seal further comprises an edge rib on an end surface.
The seal assembly for inhibiting toner leak comprises a j-seal having a lower j-shaped portion for receiving and slidably sealing a roll and an upper seat portion, the upper seat portion has a first upper seat seal, a second upper seat seal and a gap defined between the first upper seat seal and the second upper seat seal, a doctor blade seal has a tongue disposed at ends of the doctor blade seal, the tongue positioned between the first upper seat seal and the second upper seat seal and interlocking the j-seal and the doctor blade seal, the doctor blade seal sealing along three edges of the j-seal, a doctor blade assembly disposed on the doctor blade seal so that the doctor blade engages the first upper seat seal, the second upper seat seal, the upper seat portion of said j-seal and the doctor blade seal. The doctor blade assembly includes at least one bracket and a doctor blade. The first upper seat seal is an upper seat inner seal. The upper seat inner seal is disposed at an angle from a front surface of the j-seal. The second upper seat seal is an upper seat outer seal. An upper edge of the upper seat outer seal is curved tapered to provide an inwardly directed component force on the second upper seat seal to improve sealing. The seal assembly further comprises a recess defined by at least two surfaces of the doctor blade seal, the recess receiving the upper seat inner seal of the j-seal.
A seal assembly for preventing toner leakage comprises a first j-seal having a first upper seat portion, a second j-seal having a second upper seat portion, a doctor blade seal extending between the first j-seal and the second j-seal, ends of the doctor blade seal disposed within the respective first upper seat portion and the second upper seat portion, each of the first and second upper seat portions having a upper seat inner seal and an upper seat outer seal, a gap defined between each of the upper seat inner and outer seals, the doctor blade seal having a tongue disposed within each respective gap interlocking the first and second j-seals with the doctor blade seal, the tongue sealing within a corner defined by a doctor blade and the doctor blade bracket. The seal assembly further comprises an upper tapered edge on each of the upper seat outer seal. The seal assembly further comprises the upper seat inner seal is disposed at an acute with respect to the upper seat outer seal. The seal assembly further comprises a doctor blade assembly. The doctor blade assembly captures the doctor blade seal within the first and second seat portions of the j-seals.
The aforementioned features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
The following description and drawings illustrate embodiments of the invention sufficiently to enable those skilled in the art to practice it. It is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. For example, other embodiments may incorporate structural, chronological, electrical, process, and other changes. Examples merely typify possible variations. Individual components and functions are optional unless explicitly required, and the sequence of operations may vary. Portions and features of some embodiments may be included in or substituted for those of others. The scope of the invention encompasses the appended claims and all available equivalents. The following description is, therefore, not to be taken in a limited sense, and the scope of the present invention as defined by the appended claims.
Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted,” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. In addition, the terms “connected” and “coupled” and variations thereof are not restricted to physical or mechanical connections or couplings.
In addition, it should be understood that embodiments of the invention include both hardware and electronic components or modules that, for purposes of discussion, may be illustrated and described as if the majority of the components were implemented solely in hardware. However, one of ordinary skill in the art, and based on a reading of this detailed description, would recognize that, in at least one embodiment, the electronic based aspects of the invention may be implemented in software. As such, it should be noted that a plurality of hardware and software-based devices, as well as a plurality of different structural components may be utilized to implement the invention. Furthermore, and as described in subsequent paragraphs, the specific mechanical configurations illustrated in the drawings are intended to exemplify embodiments of the invention and that other alternative mechanical configurations are possible.
The term image as used herein encompasses any printed or digital form of text, graphic, or combination thereof. The term output as used herein encompasses output from any printing device such as color and black-and-white copiers, color and black-and-white printers, and so-called “all-in-one devices” that incorporate two or more functions such as scanning, copying, printing, and faxing capabilities in one device. Such printing devices may utilize ink jet, dot matrix, dye sublimation, laser, and any other suitable print formats. The term button as used herein means any component, whether a physical component or graphic user interface icon, that is engaged to initiate output. The term media and paper may be used interchangeably herein and may include plain paper, glossy photo paper, coated paper, card stock, index cards, labels, envelopes, transparency, MYLAR, fabric, or other printable materials. The term operations panel, as used herein, means an interactive display allowing for menu display, menu selections, image viewing, editing of images, correction of error conditions and other operations and control functions. The term peripheral may include a single function or multi-function, or all-in-one, device which may be connected to a host computer, network connected or may be a stand-alone, which is a device which may function independently of any host computer.
The exemplary embodiments described herein provide a seal assembly which inhibits toner leakage from around the area of the developer housing and the doctor blade assembly at ends of the developer roll.
Referring now to
Beneath the access doors 14, 26 is an input tray access door 30. When the input tray access door 30 is opened with a release 32, an input tray (not shown) is accessible to load the printer 10 with media. The input tray may hold a stack of media for printing and further defines a starting point of a media feedpath (not shown) extending from the media input tray to a media output tray 36. The media feedpath may be a duplex feedpath or a simplex feedpath. The media output tray 36 is located on top of the housing 12 and generally extends rearwardly to store printed media processed by the laser printer 10.
Referring now to
The developer assembly 40 comprises seals 70 at ends of the developer roll D. The developer roll D is exploded for clarity, so that the seals 70 may be seen. The seals 70 are substantially j-shaped to receive the developer roll, although other curvilinear shapes may be utilized. The upper portion of the j-seal 70 is slightly curved to substantially match the deflected shape of a blade 54. The lower portion of the j-seal 70 is curved to receive the developer roll D. Disposed above the seals 70 is a doctor blade seal 60, which extends in a length that is parallel to the axial dimension of the developer roll. Also disposed above the seals 70 is a doctor blade bracket assembly 50 comprising at least one first bracket 52 and a doctor blade 54. Like the doctor blade seal 60, the doctor blade bracket assembly 50 also extends in a direction which is substantially parallel to the axial dimension of both the toner adder roll 56 and developer roll D. The doctor blade seal 60 is captured between the doctor blade bracket assembly 50 and the j-seal 70 or the lid 43. The doctor blade 54 engages a developer roll to scrape excess toner from the surface of the developer roll, which provides a consistent level of toner to the imaging or photoreceptive drum of the printer 10. The doctor blade seal 60 is seated on the j-seals 70 to inhibit leakage of toner near ends of the developer roll and between the lid 43 and the developer housing 42. The doctor blade bracket assembly 50 compresses the doctor blade seal 60 to improve sealing in this area.
Referring now to
The blade 54 extends from the bracket 52 toward a peripheral surface of the developer roll D in order to scrape excess toner from the outer surface of the developer roll D. The blade 54 is generally rectangular in shape having a long or width-wise dimension substantially parallel to the direction of the axial dimension of the developer roll. The blade 54 includes a front surface 55 and a rear surface 57. The blade 54 is straight in its natural state, but in order to provide a “doctoring” force on the developer roll D has a slight curvature due to interference with the developer roll D upon installation. In addition, the blade 54 has notches near ends of the blade for removing all toner from the ends of the developer roll D where printing does not occur. The blade 54 may also receive an electrical potential in order to charge the developer roll D with a desired polarity during operation. The lower surface of the bracket 52 engages an upper surface 62 of the doctor blade seal 60, so as to capture the seal 60 between the doctor blade assembly 50 and the j-seal 70. According to the exemplary embodiment, the blade 54 may be formed of phosphor bronze to provide the desired elasticity and electrical conductivity or alternatively may be formed a hardened stainless steel to provide a desired elasticity and also withstand corrosion which might damage the developer roll. Other materials may also be utilized.
An end portion 61 of the doctor blade seal 60 is shown above one of the j-seals 70. The doctor blade seal 60 has first and second ends 61 (
The doctor blade seal 60 has an upper surface 62, a lower surface 63 and a plurality of sides extending between the upper and lower surfaces 62,63. Along the front of the doctor blade seal 60, toward the doctor blade 54, a tongue 64 is integrally formed with and extending from the doctor blade seal end 61. On an outer side of the tongue 64 is an end surface 65 (
Beneath the doctor blade seal 60, the j-seal 70 comprises an upper seat portion 72, and a developer roll leg 74, which is substantially j-shaped and depending from the upper seat portion 72. The j-seal 70 may be formed in a molding process, such as injection molding, compression molding, or other known processes for forming a plastic, such as a thermoplastic rubber having the trade name SANTOPRENE. The leg 74 has a front surface 75 comprising a plurality of grooves 76, which provide several functions. The grooves 76 “snowplow” the toner on the developer roll and capture toner between the grooves to inhibit leakage. The grooves 76 also direct the toner toward a storage area via rotation of the developer roll D (
The upper seat portion 72 comprises a seating surface 73, an upper seat inner seal or seal wall 78 and an upper seat outer seal or seal wall 80. A gap 86 is disposed between the upper seat inner seal 78 and the upper seat outer seal 80, wherein the tongue 64 may be closely received within the upper seat portion 72 to interlock the j-seal 70 and the doctor blade seal 60. The seating surface 73 also comprises an aperture made for receiving an alignment pin for proper positing of the j-seal 70 to the housing 42.
The upper seat inner seal wall 78 extends upwardly from the upper seat surface 73. The upper seat inner seal 78 is disposed at an acute angle with respect to the outer seal 80 which corresponds to that of the angled surface 68, so that the upper seat inner seal 78 and angled surface 68 engage one another in sealing fashion. Further, the upper seat inner seal 78 is received within the recess defined by the surfaces 66, 68, 69.
Referring additionally now to
Also extending from the end surface 65 of seal 60 is an edge rib 67. The rib 67 is deformed so as to be positioned over an edge of the housing wherein the j-seal 70 is seated. Since the rib 67 extends outwardly from the end surface 65, the upper seat outer seal 80 does not extend rearwardly the entire length of the seating surface 73. Accordingly, space is provided for the edge rib 67 to extend outwardly beyond the outer seal wall 80.
Referring now to
Referring now to
The foregoing description of the various embodiments of the invention has been presented for purposes of illustration. It is not intended to be exhaustive or to limit the invention to the precise steps and/or forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be defined by the claims appended hereto.
This patent application is related to the U.S. patent application Ser. No. ______, (Attorney Docket No. 2007-0191.01) filed even date herewith, entitled “Developer Roll Lip Seal” and assigned to the assignee of the present application. The lip seal disclosed in this related application may be used in combination with the upper seal disclosed herein but it may also be used independently of this upper seal.