The present invention relates generally to the field of image formation devices and in particular to a coupling retraction mechanism for a color electrophotographic printer.
The use of removable cartridges in image formation devices is well known. Such cartridges typically include a photoconductive member upon which latent images are formed, as well as a reservoir of toner and rollers to apply toner to the photoconductive member to develop the latent image. A wide variety of designs and mechanisms are employed in the art for inserting and removing such cartridges. In particular, inserting a removable cartridge in an axial direction, whereby a drive receiver on the end of the cartridge mates with a rotary drive coupling as the cartridge is inserted, is well known in the art. Other insertion/removal means are known, whereby the cartridge is inserted/removed in a direction at right angles to the cartridge's rollers' axes. Such systems typically require a manual, mechanical decoupling of a rotary drive coupler from a drive receiver on the cartridge, to provide mechanical clearance for the insertion/removal of the cartridge.
Modern, compact, multicolor image formation devices typically include a plurality of removable cartridges, such as three or four, each supplying a different color of toner. One recent development in the image formation arts is the separation of the functions of toner supply, and image formation and transfer, into different removable cartridges. Such a system may include a large number (e.g., eight) separately removable cartridges, each of which must be mechanically coupled to the image forming device, to provide rotary power to the cartridge. Additionally, other elements in the image forming device may require decouplable rotary power.
The present invention relates to an image forming apparatus containing a plurality of rollers disposed with generally parallel axes. A retraction plate is movable between engaged and retracted positions. A plurality of rotational couplings are retained axially by the retraction plate, with each rotational coupling operative to transmit a rotary force to each roller when the retraction plate is in the engaged position. The couplings move laterally in an axial direction of the rollers as the retraction plate moves between the engaged and retracted positions, in response to an applied force.
In another aspect, the present invention relates to a coupling retraction mechanism for an image forming apparatus. The mechanism includes a retraction plate movable between engaged and retracted positions. A plurality of rotational couplings retained axially by the retraction plate are operative to couple rotational forces to a corresponding plurality of rollers disposed in the image forming apparatus when the retraction plate is in the engaged position. The mechanism also includes an articulating member movable in a first lateral direction along the retraction plate in response to an applied force, wherein movement of the articulating member in the first lateral direction is operative to translate the retraction plate in a second lateral direction, generally orthogonal to the first lateral direction, thereby moving the plate between the retracted and engaged positions.
Within the image forming apparatus body 12 and/or in the subunit 13, the image forming apparatus 10 includes registration rollers 22, a media sheet transfer belt 24, one or more removable developer units 26, a corresponding number of removable photoconductor units 28, an imaging device 30, a fuser 32, reversible exit rollers 34, and a duplex media sheet path 36, as well as various rollers, actuators, sensors, optics, and electronics (not shown) as are conventionally known in the image forming apparatus arts, and which are not further explicated herein.
The internal components of the developer units 26 and photoconductor units 28 are briefly described (these components are not all explicitly depicted in the drawings). Each developer unit 26 is a removable cartridge that includes a reservoir holding a supply of toner, paddles to agitate and move the toner, a toner adder roll for adding toner to a developer roll 27, a developer roll 27 for applying toner to develop a latent image on a (separate) photoconductive drum, and a doctor blade to regulate the amount of toner on the developer roll 27. Each photoconductor unit 28 is a separate removable cartridge that includes a photoconductive (PC) drum 29. The PC drum 29 may comprise, for example, an aluminum hollow-core drum coated with one or more layers of light-sensitive organic photoconductive materials. The photoconductor unit 28 also includes a charge roll for applying a uniform electrical charge to the surface of the PC drum 29, a photoconductor blade for removing residual toner from the PC drum 29, and an auger to move waste toner out of the photoconductor unit 28 into a waste toner container (not shown).
Each developer unit 26 mates with a corresponding photoconductor unit 28, with the developer roll 27 of the developer unit 26 developing a latent image on the surface of the PC drum 29 of the photoconductor unit 28 by supplying toner to the PC drum 29. In a typical color printer, three or four colors of toner—cyan, yellow, magenta, and optionally black—are applied successively (and not necessarily in that order) to a print media sheet to create a color image. Correspondingly,
The operation of the image forming apparatus 10 is conventionally known. Upon command from control electronics, a single media sheet is “picked,” or selected, from either the primary media stack 16 or the manual input 20. Alternatively, a media sheet may travel through the duplex path 36 for a two-sided print operation. Regardless of its source, the media sheet is presented at the nip of a registration roller 22, which aligns the sheet and precisely controls its further movement into the print path.
The media sheet passes the registration roller 22 and electrostatically adheres to transport belt 24, which carries the media sheet successively past the photoconductor units 28. At each photoconductor unit 28, a latent image is formed by the imaging device 30 and optically projected onto the PC drum 29. The latent image is developed by applying toner to the PC drum 29 from the developer roll 27 of the corresponding developer unit 26. The toner is subsequently deposited on the media sheet as it is conveyed past the photoconductor unit 28 by the transport belt 24.
The toner is thermally fused to the media sheet by the fuser 32, and the sheet then passes through reversible exit rollers 34, to land facedown in the output stack 35 formed on the exterior of the image forming apparatus body 12. Alternatively, the exit rollers 34 may reverse motion after the trailing edge of the media sheet has passed the entrance to the duplex path 36, directing the media sheet through the duplex path 36 for the printing of another image on the back side thereof.
Preferably, all of the drive mechanism couplings to all developer units 26 and photoconductor units 28 should be decoupled, or retracted, simultaneously, allowing any cartridge to be removed and/or replaced without the necessity of individually retracting its drive mechanism coupling. More preferably, the drive mechanism couplings should be automatically retracted from the cartridges whenever the subunit 13 is opened to allow access to the cartridges, without requiring conscious action on the part of the operator. According to various embodiments of the present invention, all of the drive couplers supplying rotary power to the developer units 26 and the photoconductor units 28 are retracted simultaneously, by actuation of a retraction plate 46 within a coupling retraction mechanism 40, 60, as described herein.
In particular, a pivoting coupling retraction mechanism according to one embodiment of the present invention is depicted in
The developer unit couplers 42 and photoconductor unit couplers 44 are biased in the positive z-direction (out of the page as depicted in
In the embodiment depicted in
In another embodiment of the present invention, the retraction plate 47 is operative to move the developer unit couplers 42 and the photoconductor unit couplers 44 between engaged and retracted positions by translating in the axial direction of the couplers.
The drive gear 62, preferably a spur gear as shown, is rotated in a counter-clockwise direction to retract the couplers 42, 44, such as when the top cover 11 is opened, a disengagement lever is actuated, or the like. The drive gear 62 meshes with a drive rack 68 (preferably a spur rack) to translate the rack plate 64 in the positive x-direction, or to the right as depicted in
The upper rack plate pins 72 additionally engage in angled slots 78 formed in the retraction plate bracket 66. The angled slots 78 are disposed at an acute angle from the x-direction. As the upper rack plate 64 translates in the positive x-direction (to the right), the rack plate pins 72 exert a component of force on the angled slots 78 in the retraction plate bracket 66 in the negative z-direction, i.e., into the plane of the paper as depicted in
Referring to
Referring to
As the lower rack plate 88 translates in the positive x-direction (to the right), a force in the negative z-direction (i.e., into the plane of the page as depicted in
The lower rack plate 88 is constrained to motion in the x-direction by lower x-slot 96 formed in the lower gearbox frame 49. In addition to engaging the sloped cam surface 92, the pin 90 additionally engages a z-slot 98 formed in the lower gearbox frame 49. This constrains the motion of the translating retraction plate 47 to the z-direction. That is, the translating retraction plate 47 is constrained to motion in the axial direction of the drive couplers 42, 44.
Following installation or removal of developer units 26 and/or photoconductor units 28, the subunit 13 is closed. This preferably rotates the drive gear 62 in the clockwise direction, which engages drive rack 68 and translates the upper rack plate 64 in the negative x-direction, or to the left as depicted in
Simultaneously, the upper coordinating rack 70 drives the upper pinion 80 and, via shaft 82, the lower pinion 84 in a clockwise direction. The lower pinion 84 engages lower coordinating rack 86 to translate the lower rack plate 88 in the negative x-direction. As the sloped cam surface 92 of the lower rack plate 88 translates in the negative x-direction, it allows the pin 90, and consequently the translating retraction plate 47, to translate in the positive z-direction, thereby engaging couplers 42, 44 with drive receivers 50, 52. Note that in this embodiment, the translating retraction plate 47 is biased to the positive z-direction, such as by one or more springs. Alternatively, the lower end of the translating retraction plate 47 may be actively forced to translate in the positive z-direction by the use of an angled slot (similar to angled slots 78 formed in the retraction plate bracket 66 as depicted in
The drive gear 62 is preferably driven in a counter-clockwise direction when the top cover 11 of the image forming apparatus 10 is opened, causing the couplers 42, 44 to automatically retract from the cartridge drive receivers 50, 52. This allows the subunit 13 to be opened (a mechanical interlock, not shown, prevents the subunit 13 from being opened until the top cover 11 is opened). Similarly, closing the top cover 11 (after closing the subunit 13) preferably rotates the drive gear 62 in a clockwise direction, translating the couplers 42, 44 to the engaged position. Alternatively, the drive gear 62 may be driven by a lever actuated by a user. As yet another alternative, the drive gear 62 may be driven by a motor, in response to a positive input by a user such as pressing a button or entering a command on a user interface, or in response to a condition or operation, such as attempting to open the subunit 13 some other access door or panel. In this manner, a plurality of rotational drive couplings 42, 44 are simultaneously engaged or disengaged with a corresponding plurality of removable cartridges 26, 28.
Referring back to
Although described herein with reference to an image forming apparatus 12 having plural, separate developer units 26 and photoconductor units 28, the present invention is not limited to such an embodiment. For example,
The present invention is not limited to the coupling of a rotary drive shaft to a removable cartridge. Rather, the present invention may be advantageously utilized to simultaneously, removably couple a plurality of rotary drive shafts and drive receivers, as may be necessary or desired within the image forming apparatus 10.
As used herein, the term roller refers to a generally cylindrical element, which may for example and without limitation include an auger or paddle, a toner supply roller, a developer roller, a charge roller or a photoconductive drum. The term photoconductive member refers to any element in an image forming apparatus on which a latent image is formed by incident optical energy, the latent image being developed by toner or developer. The term developer member refers to any element in an image forming apparatus that supplies toner or developer to develop a latent image on a photoconductive member. The term subunit refers to a subassembly of the image forming apparatus 10, which may for example and without limitation comprise a door, an access panel or the like. Opening or closing the subunit refer to the operations of uncoupling and separating the subunit from the main housing of the image forming apparatus, and of operatively engaging the subunit with the image forming apparatus, respectively. The terms coupling and coupler are used interchangeably herein.
Although the present invention has been described herein with respect to particular features, aspects and embodiments thereof, it will be apparent that numerous variations, modifications, and other embodiments are possible within the broad scope of the present invention, and accordingly, all variations, modifications and embodiments are to be regarded as being within the scope of the invention. The present embodiments are therefore to be construed in all aspects as illustrative and not restrictive and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.