Flexible toner feed member

A toner feeding device and method to supply toner from a toner reservoir to a selected location in the printer such as a toner supply roll. The toner feeding device may contact with a portion of an inner wall of a toner reservoir and may flex and may subsequently recover to convey toner particles.

FIELD OF THE INVENTION

This invention relates to image forming devices including a toner cartridge assembly and a system for feeding of toner to a selected location in a printer.

BACKGROUND OF THE INVENTION

Image forming devices including copiers, laser printers, facsimile machines, and the like, may include a photoconductive drum having a rigid cylindrical surface that is coated along a defined length of its outer surface. The surface of the photoconductor may be charged to a uniform electrical potential and then selectively exposed to light in a pattern corresponding to an original image. Those areas of the photoconductive surface exposed to light may be 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 may be used for forming the image. The toner may be stored in a reservoir or sump adjacent to the photoconductor and may be transferred to the photoconductor by a developer roll. The thickness of the toner layer on the developer roller may controlled by a nip, which is formed between a doctor blade and the developer roller.

A recording sheet, such as a blank sheet of paper, may then be brought into contact with the photoconductive surface and the toner thereon may transferred to the recording sheet in the form of the latent electrostatic image. The recording sheet may then be heated thereby fusing the toner to the sheet.

SUMMARY OF THE INVENTION

In a first exemplary embodiment, the present invention relates to a toner assembly for supplying toner to a selected location in a printer comprising a toner feeding member and a toner reservoir capable of storing toner. The toner reservoir includes an inner wall and a protruding feature. The toner feeding member is capable of engaging with the protruding feature on the wall of the reservoir and capable of disengaging with the protruding feature on the wall of the reservoir to at which point it may supply toner to a selected location in the printing device.

In a second exemplary embodiment the present invention relates to toner cartridge comprising a cylindrical reservoir capable of storing toner. The reservoir may have a cylindrical wall including a protruding feature. A toner feeding member may be disposed in the reservoir and is capable of moving toner towards a toner supply roll, where the toner feeding member includes a first end and a second end. The first end of the toner feeding member may be coupled to a driven shaft and the second end may be capable of being rotated by the shaft and into contact with the protruding feature in the cylindrical wall of said reservoir to cause the feeding member to flex.

In a third exemplary embodiment the present invention relates to a method of conveying toner from a reservoir to a selected location in a printer. The method may comprise providing a toner feeding member and providing a reservoir capable of storing toner wherein the reservoir includes an inner wall and a protruding feature. The toner feeding member may engage with the protruding feature on the wall of the reservoir and flex. The toner feeding member may then disengage with the protruding feature on the wall of the reservoir and supply toner to a selected location in a printer. The supply of toner may be accomplished by launching toner particles on the toner supply member when recovering from the indicated flex.

DETAILED DESCRIPTION OF THE INVENTION

A schematic construction of an image-forming electrophotographic apparatus having a process cartridge installed therein is described herein.FIG. 1is a sectional view of an embodiment of an image-forming apparatus, such as a laser printer.FIG. 2is a sectional view of a cartridge that may be utilized in the apparatus ofFIG. 1.

As shown inFIG. 1, the image-forming apparatus “A” projects a light image based on image information from an optical means1so that a developing agent (referred to as “toner”) image is formed on a photosensitive drum7which is an image carrier. Then, a recording medium2may be fed by feeding means3in synchronization with the formation of a toner image, and the toner image formed on the photosensitive drum7in the image-forming section, which is integrally included within a process cartridge “B”. The toner image may be transferred to the recording medium2by transfer means4. The recording medium2may then be transferred to fixing means5where the transferred toner image may be fixed onto the recording medium2, which is then ejected onto an ejection tray6.

As shown inFIG. 2, the process cartridge B, which constitutes the image-forming section, makes a photosensitive drum7rotate to uniformly charge the surface thereof by charging means8and exposes a light image from the optical means onto the photosensitive drum7via an exposure section9to form a latent image on the photosensitive drum7. A toner image corresponding to the latent image is formed by developing means10, thus making the image visible. After the toner image is transferred to the recording medium2by the transfer means4, toner remaining on the photosensitive drum7may be removed by cleaning means11.

These elements, including the photosensitive drum7, may be housed inside a toner development frame member12and a cleaning frame member13, which together constitute a housing, so that they are formed into a cartridge. Each part of the process cartridge B may be provided with a sealing member for preventing the toner from leaking.

The construction of each part of the image-forming electrophotographic apparatus A may be explained in the following order: optical means, feeding means, transfer means, fixing means, and cartridge mounting means.

The optical means1may project a light image onto the photosensitive drum7by projecting light on the basis of image information read from an external apparatus or the like. As shown inFIG. 1, a laser diode1b, a polygon mirror1c, a scanner motor1d, and an image-forming lens1emay be housed inside an optical unit1aof the main body14of the apparatus. When, for example, an image signal is supplied from an external apparatus, such as a computer or word processor, the laser diode1bemits light in response to the image signal, and projects the light onto the polygon mirror1cas image light. Polygon mirror1cmay be rotated at high speed by the scanner motor1d. The image light reflected by the polygon mirror1cmay projected onto the photosensitive drum7via the image-forming lens1eand reflecting mirror1f. The surface of the photosensitive drum7may thus be selectively exposed to form a latent image corresponding to the image information.

The feeding means3for feeding the recording medium2(e.g., recording paper, OHP sheet, cloth, or thin plate) comprises the following components. A loading portion of a cassette3amay be provided in the inner bottom portion of the main body14of the apparatus. When an image formation start signal is input, the recording media2within the cassette3amay be fed one-by-one from the top of the stack by a pickup roller3b, feeding rollers3cand follower rollers3d, pressed against the feeding roller3c.

The sheet of recording medium2may be fed to the nip portion between the photosensitive drum7and the transfer means4in synchronization with the performing of the image-formation operation described above; the image is transferred to the recording medium. The recording medium2onto which a developed image has been transferred may be fed to the fixing means5and then ejected onto the ejection tray6by a pair of intermediate ejection rollers3eand a pair of ejection rollers3f. A pair of guide members3gfor guiding the feeding of the recording medium2may be provided between each of the above-mentioned pairs of rollers.

The transfer means4transfers the developed latent image or toner image formed on the photosensitive drum7in the image-forming section onto the recording medium2. The transfer means4consists of the transfer roller4as shown inFIG. 1. That is, the recording medium2may be pressed by the transfer roller4against the photosensitive drum7of the loaded process cartridge B. A voltage having a polarity opposite that of the latent image formed on the photosensitive drum7may be applied to the transfer roller4so that the toner on the photosensitive drum7may be transferred to the recording medium2.

The fixing means5may fix the toner image transferred to the recording medium2by applying heat and pressure to the recording medium2carrying the toner image. As shown inFIG. 1, the fixing means5may comprise a driving rotating roller5ahaving a heater5btherein, and a fixing (pressure) roller5c, rotating in a driven manner in pressed contact with the drive roller5a. More specifically, when the recording medium2to which the toner image has been transferred moves between drive roller5aand fixing roller5c, heat may be applied by the heater located in the driving rotating roller5aand pressure may be applied to the recording medium by the fixing roller5c, thereby causing the toner (which comprises a colorant and a thermoplastic component) on the recording medium2to melt and become fixed to the recording medium2.

A process cartridge loading means by which the process cartridge B is loaded into the image forming apparatus is disposed within the apparatus A. Loading and unloading of the process cartridge B to and from the main body14of the apparatus may be performed by opening an open/close cover15. Open/Close cover15may be provided with a conventional hinge (not shown) so that it can be opened or closed, and is mounted in the upper portion of the main body14of the apparatus. Opening the open/close cover15reveals a cartridge loading space provided inside the main body14of the apparatus, including conventional left and right guide members (not shown) mounted on the left and right inner-wall surfaces of the main body14. Each of these guide members is provided with a guide for inserting the process cartridge or toner assembly B. The process cartridge or assembly B may be inserted into and along the guides, and by closing the open/close cover15, the process cartridge B may be loaded into the image-forming apparatus A.

The components of the process cartridge or assembly B will now be described. The process cartridge or assembly B may comprise an image carrier and at least one process means. The process means includes charging means for charging the surface of the image carrier, developing means for forming a toner image on the image carrier, cleaning means for cleaning the toner remaining on the surface of the image carrier, and the like. In the process cartridge B as shown inFIG. 2, the charging means8, the exposure section9, the developing means10, and the cleaning means11may be arranged around a photosensitive drum7, which is an image carrier. These elements may be housed within a frame member formed of the toner development frame member12and the cleaning frame member13so that they may be formed into one unit, thus making it possible to load and unload the unit into and out of the main body14of the apparatus. The process cartridge B may comprise the following elements: the photosensitive drum7, the charging means8, the exposure section9, the developing means10and the cleaning means11.

The photosensitive drum7may have an organic photosensitive layer coated onto the outer peripheral surface of a cylindrical drum base formed from aluminum. The photosensitive drum7may be rotatably mounted on a frame member of the cartridge and the driving force of a drive motor disposed in the main body14of the apparatus may be transmitted to a drum cap (not shown). As a result, the photosensitive drum7may be caused to rotate in the direction of the arrow inFIG. 1in accordance with the performance of an image-forming operation.

The charging means8may be used to uniformly charge the surface of the photosensitive drum7. Preferably, a so-called contact charging method in which the charging means8is mounted on frame member14may be used.

The charging means8may be brought into contact with the photosensitive drum7so that the charging means8contacts the photosensitive drum7during the image formation. A DC voltage may be applied to the charging means8and the surface of the photosensitive drum7may be uniformly charged.

An exposure section9exposes a light image projected from the optical means onto the surface of the photosensitive drum7uniformly charged by the charging roller8so that a latent image may be formed on the surface of the photosensitive drum7. An opening9for guiding the light image onto the top surface of the photosensitive drum7may be provided to form the exposure section.

As shown inFIG. 2, the developing means may include a toner reservoir10aor housing for toner, and a rotary paddle toner feeding member10b. The toner feeding member10bor agitator may be provided within toner reservoir10aand rotates as shown inFIG. 2to circulate toner within the toner reservoir10aand transfer the toner to a toner roll10c. A developer roll10dmay form a thin toner layer on the surface thereof as a result of its rotation against the toner roller and may be pressed against the photosensitive drum7. The toner feeding member may act as an agitator for the toner and may be generally configured as a paddle that extends substantially the width of the toner reservoir10aand may contain a series of openings to aid in breaking up clumps of toner. The size of the paddle may be such that during rotation the outer end or tip of the paddle may come within close proximity to the inner surface of cylindrical wall12ato agitate the toner and move it towards roll10c. The paddle10bmay have a variety of configurations and may be substantially flat.

A development blade (also called a “doctor blade”)10e may be disposed adjacent the developer roll10dto regulate the thickness of the toner layer formed therebetween. An electric charge may be imparted to the toner by a biasing voltage on the doctor blade.

As shown inFIG. 2, the cleaning means11may comprise a cleaning blade11a, positioned in contact with the surface of the photosensitive drum7for scraping off the toner remaining on the photosensitive drum7, a skimming seal11b, positioned below the cleaning blade11aand arranged in weak contact with the surface of the photosensitive drum7, for retaining the toner which has been scraped off, and a waste toner well11cfor storing the scraped-off waste toner.

One aspect of the present invention is directed at supplying toner to the toner supply roll10c. The toner may be supplied so that it may preferably cover the toner roller10cand it may therefore preferably reduce or prevent starvation of the developer roller10d. As shown inFIG. 4, process cartridges may have a geometry such that they may fit within the confines of an imaging device and may take up as little space as possible yet provide an adequate supply of toner.

In one embodiment of the present invention, as shown inFIG. 3, a cartridge B′ for an imaging apparatus may have a toner storage reservoir10a′. Rotation of agitator10b′ in the direction as shown by the arrow34amay move toner from the reservoir10a′ over a sill33atowards the toner roll10c. The toner roll may then be preferably supplied and covered with toner.

To impart kinetic energy to the toner particles to move them forward to the toner roll10c, a flexible or elastomeric toner feeding member10b′ may be employed. The toner feeding member may be employed in combination with an interfering feature or wall12bwhich may be formed in the toner frame member12′. As shown inFIG. 2the toner frame member12may generally be cylindrical in shape so that the toner feeding member10bmay travel on a path within the frame to agitate and feed toner without interfering with the wall12a. The toner feeding member10b′ of the present invention (seeFIG. 3) preferably may be rotated by shaft24such that the member10b′ is not in contact with the inner circumference of wall12a, but may make contact or interfere with non-circumferential wall or feature12b. This interference may cause the member10b′ to deflect or flex such that upon further rotation of the member by the shaft, the member clears the interference and recovers to its original shape, transferring energy to any toner particles that it may have encountered.

The material that may form the flexible toner feeding member10b′ of the present invention may be selected so that it may be flexed when it is positioned as between the inner reservoir wall or interfering feature12band drive axis24as illustrated inFIG. 3. When flexed, the substrate material of the toner feeding member may then exhibit an elastic response that may be sufficient to convey toner to the toner roll. By elastic response it should be understood that when the toner feeding member is flexed it may initially provide a resistance to such flex and may then respond back, to some degree, towards its original (unflexed) state. This elastic response may simply be realized by the application of a torque to the member10b′ by the drive shaft24effectuated through the engagement of one end of the toner feeding member with the toner reservoir wall or interference12b.

With respect to the angle for flexing, θ illustrated inFIG. 3, the flexure of member10b′ may preferably be between about 135° to less than 180° and all incremental values therebetween including, e.g., 140°, 145°, 150°, etc. More generally, for a member that is initially flat, the flexure may be between 90° to less than about 180°, and all incremental values therebetween, including 100 degrees, 115 degrees, etc. Therefore, any substrate material for the member10b′ that flexes to provide energy which may be imparted to the toner particles, when positioned between the drive axis24and interfering reservoir wall12bin the cartridge, may be suitable for use in the present invention.

In one embodiment, the substrate material for the toner feeding member may be a polymer strip, and may be either a thermoplastic or thermoset material. The polymer may include polyester, such as polyethylene terephthalate (PET), polycarbonate, polyetherimide, and other polymers. For example, the substrate may include elastomeric materials such as natural or synthetic rubbers, thermoplastic elastomers (e.g., styrene-butadiene copolymers, polyurethane elastomers, polyester-based elastomers) and blends thereof, as well as thermoset elastomers. All such polymers may be present as a film (e.g. extruded or cast) or as a molded substrate, preferably of unitary construction.

In the present invention, the flexible toner feeding member10b′ may, preferably comprise a biaxially oriented polyester, such as Mylar®. The substrate material may have a tensile modulus Etensileof between about 300,000 psi and about 1,000,000 psi and all values and increments therebetween. The tensile elongation in the machine direction (MD) may be about 115% and the tensile elongation in the transverse direction may be about 90%. The member material may also preferably exhibit little to no creep (strain deformation v. time) through-out the lifecycle of the electrophotographic device at relevant working temperatures. In this manner, the drive shaft24may apply a fairly uniform torque to the paddle through-out its intended lifetime of use to agitate and advance toner to the toner roll10c. In addition, regardless of modulus values, the substrate may have a thickness preferably between 0.075 mm and 0.250 mm, and all increments therebetween including 0.125 mm, 0.150 mm, etc.

The toner feeding member10b′ (seeFIG. 5) may also be configured to include a plurality of fingers22at spaced longitudinal portions thereof. The fingers22may have their free ends joined to each other by a connector23. To form a blade containing open spaces, the fingers22, the connector23, and the shaft24may preferably be a single piece of unitary construction formed of a plastic, and be capable of flexing for a number of cycles over its life. The openings25between the fingers22, connector23and shaft24may allow toner to be agitated and lifted by the rotary action of the member10b′ around the drive shaft24. The openings so-formed may be any of a variety of geometric shapes (e.g., round, oval, square, trapezoidal, triangular, etc.) which may ensure that toner is fed more evenly to the toner roll10c. As the member10b′ rotates counter clockwise (seeFIG. 3) in the direction of the arrow34a, toner may tend to be moved over the sill33aof the reservoir10a′. The openings25may also provide lower resistance thereto as the member passes through the toner.

As best shown inFIG. 3, the toner that may be moved over the sill33amay be presented to and preferably may cover the toner roll10c. The toner roll may then interact in the manner as previously described with a developer roll10dand then in turn with a photoconductive (PC) drum7. The PC drum may be in the media path for applying text and graphical information to the print receiving media2that is presented to the drum.

The interference, shown as dotted line12b, may preferably be formed in the wall12′ of the cartridge B′, near the top33aof the wall12′ between the member10b′ and the reservoir inner wall12a. This interference or feature may provide resistance to the rotation of member10b′ by the shaft24and may create potential energy from the torque applied to the member. This energy may then be transferred as kinetic energy to the toner particles on the member10b′ when the member clears the interference and recovers elastically. The effect may be seen inFIG. 3where the member, in this case a paddle, shown in cross-section is deflected or flexed by the interfering wall12b. The interference may deform the normal shape of the member (seeFIG. 5), creating torque energy which may build up as the member10b′ deforms. When there is sufficient deformation in the member, driven by the shaft24, the end contacting the wall12bmay slide past the interfering wall with increased potential energy. The energy imparted to the toner residing on the fingers22and connector23, may “flick” and launch the toner to cover the toner roll10c. This, in turn, may force more of the toner to be evenly distributed over the toner roll and may fill the area surrounding the toner roll.

In the present invention, a change in the actual geometrical shape of the wall12a, shown as dotted wall section12binFIG. 3of the frame12′, may also be relied upon to regulate the amount of toner that may “flick” towards the toner roll10c. As illustrated, a relatively smooth projection or bump can be seen. However, it can be appreciated other geometries for the interfering portion of the wall are possible, including but not limited to, a smooth transition, a sharp projection, a rounded projection and all variations thereof.

By creating an interference12blocally, that is, for only a portion of the inner circumference of the frame member12′, the toner feeding member10b′ may be deflected or flexed for a relatively short portion of the total travel of the feeding member and the tendency for the member to undergo plastic creep may be minimized. By plastic creep it is reference to a loss in elastic recovery properties. Thus, the toner feeding member10b′ of the present invention, which may be of unitary construction (seeFIG. 5), may better retain its elastic properties as it would not be in a flexed condition throughout the entire rotation of the shaft24. In that regard, the toner feeding member may have a longer life and may retain its elastic properties for a relatively longer period of time. This may also translate into more efficient production of a greater number of copies.

In addition, by creating a local interference, such as through a feature that protrudes inwards from the inner circumferential wall12′ of the cartridge at a selected location, rather than a circumferential wall that interferes with the agitator for nearly all of the path of its travel, additional space or volume may be provided for toner storage.

While the interference12binFIG. 3is shown in section such that the shape may be uniform across the width of the reservoir, it should be understood that the shape of the interfering wall or feature may also vary across the width of the reservoir. The width of the reservoir may be understood inFIG. 3as that dimension that effectively runs in and out of the figure as it appears on the page, and which also generally corresponds to the length of the shaft24. In this fashion more flexure of the member may occur at a desired location, for instance, towards the lateral ends of the toner feeding member (see the dotted line portions12binFIG. 3A), which may then ensure improved coverage of the toner roll at its lateral ends.

It should further be understood one may control the geometry of the dotted protruding wall section12bto provide, e.g., a more vertical configuration near the sill33aor top of the wall12′ relative to the axis of rotation of the drive shaft24. In this fashion, toner particles may be propelled or “flicked” higher and in a greater arc to clear the sill and cover the toner roll. Moreover, this interfering wall or feature12bmay create a location at the end or tip of the toner feeding member10b′ such that the end or tip may stall momentarily while the remainder of the member10b′ may continue to rotate via shaft24. Energy may then build up in the paddle due to the applied torque as the fingers22of the member10b′ deform or flex. When there is sufficient deformation in the member10b′, the end in contact with the interfering feature12bmay then slide past that portion of the wall with greater energy. As noted, the release of this energy may then push the toner particles over the sill33aand towards the toner roll10c.

In accordance with the present invention, it has been determined that one can initially define a “mass/flick” value or (M/F)1for the toner supply member10b′ in the absence of interfering feature12b. Then, one can determine a value of “mass/flick” value or (M/F)2in the presence of interfering feature12b. It has therefore been determined that (M/F)2>(M/F)1wherein (M/F)2/(M/F)1may fall in the range of 2-10, and all incremental values therebetween.

For example, it was observed that for a selected developing means10, and a Mylar® member10b′ at a thickness of about 0.125 mm, the value of (M/F)1was about 0.28 g. When interfering feature12bwas employed with the illustrated round configuration shown inFIG. 3, and which protruded about 4.0 mm into the reservoir10a′, the value of (M/F)2was observed to be about 1.5-1.6 g. As can be appreciated, this provides about a 550% increase in “mass/flick” value and a more even coverage of the toner roll10c.

As further shown inFIG. 4, in another embodiment the cartridge B″ may include a plurality, e.g., two or more reservoirs. As shown inFIG. 4, three reservoirs40a,40b,40cmay be aligned in tandem to feed toner to the toner roll10c. The third member50amay feed toner to a second member50bwhich may feed a flexible member50c. The flexible member50cmay move the toner over sill33ato toner roll10c. The third and second members50a,50bmay be either of a flexible or of a more rigid construction.

The embodiment inFIG. 4comprises a cartridge which may allow for storage of a larger quantity of toner without increasing the height of the cartridge by using multiple reservoirs. In addition, to further minimize the height of the cartridge B″, the axis of rotation “H” of the paddles50a,50b,50cmay be lowered to be essentially equal to the height of the sill33aand slightly lower than the toner roll10c. This may allow the member50cto provide more energy to move the toner upwards toward the toner roll10c. Here again, inFIG. 4, a feature or a change in shape of wall12b′ has been illustrated on the inside wall of the cartridge B″ at the front of reservoir40c. Such change in shape may again interfere with flexible member50cas it is rotated. Note that the inner wall12b′ of reservoir40cmay no longer be circular in shape and may be shaped to provide contact with the end of member50cas the paddle is rotated counterclockwise.