Patent Application
20080143041
Reproduction apparatuses typically include sheet feeding mechanisms to reliably feed individual sheets of media from a stack of media. For a given mechanism there is an optimum window, or vertical range, within which the top of the media stack must be presented to one or more feed rolls for reliable performance. This has been traditionally achieved using an elevating plate and associated elevating mechanism for raising and lowering the media stack to position the top of the media stack within the optimum window relative to the feed rolls. In the operating mode, a nudger roll, also commonly referred to as a pre-feed roll, is positioned above the media stack in contact with the top of the media stack. Rotation of the nudger roll engages the top sheet of the media stack, causing the sheet to begin moving from the media stack to a feed path.
In addition to the use of an elevating plate, conventional media feeder mechanisms also rely on the use of solenoid with the nudger roll. The solenoid operates to lower the nudger roll from an up position above the top of the media stack to a down position engaging the top of the media stack. The operations of an elevated plate mechanism and nudger roll solenoid are coordinated. With the elevated plate in a lowered position and the nudger roll in an up position, an operator can add media to the media stack.
To allow for increased media capacity, feeding mechanisms should accommodate reasonably large stack heights. Larger stack heights increase the complexity of both elevating plate mechanisms used to raise the media stacks and nudger roll solenoids. There are significant disadvantages associated with these mechanisms in the form of high manufacturing and maintenance costs.
There is a need for feeding mechanisms that can reliably feed various types of media to marking devices or imaging devices without utilizing either a media stack raising mechanism and/or a solenoid operated mechanism for moving the nudger rolls. Eliminating the use of these mechanisms would eliminate the need for costly parts, such as solenoids, and thereby reduce manufacturing costs. Eliminating the use of a solenoid, which is inherently noisy, also provides the benefit of reduced operating noise.
Conventional feeding mechanisms employ motors to drive the feed and nudger rolls, and to operate the elevated plate mechanism. These motors are often reversible electric stepper motors, which in many cases are only operated in a single direction. There is a need for a feeding mechanism that better utilizes the capacity of reversible electric stepper motor by operating it in both of its available directions.
In embodiments, a sheet feeding assembly is provided that reliably feeds various types of media to a marking device or imaging device without requiring an elevated plate mechanism for raising and lowering a stack of media.
In embodiments, a sheet feeding assembly is provided that reliably feeds various types of media to marking devices or imaging devices without requiring a solenoid operated nudger roll.
In embodiments, a sheet feeding assembly is provided that is less expensive to manufacture and repair.
In embodiments, a sheet feeding assembly is provided that operates a reversible electric stepper motor in both directions. The assembly may include a frame with opposing sides connected by a cross member, a feed roll supported on the frame for rotation about a feed axis, a nudger support element pivotally mounted to the frame for rotational movement about a feed axis, and a nudger roll connected to the nudger support element for rotation about a nudger axis parallel to the feed axis. The assembly further includes a cam supported on the frame for rotation about a cam axis. The cam engages an extension member of the nudger support element extending outwardly from the feed axis, and is profiled to raise and lower the nudger roll as the cam rotates. The assembly further includes a reversible electric stepper motor to drive, without requiring the use of more than one motor, the feed roll, nudger roll and cam.
In embodiments, the feed roll and the nudger roll are driven in a forward direction when the motor is operated in a forward direction; and the cam is driven in a cam operating direction when the motor is operated in a reverse direction. This provides greater utilization of the capabilities of a reversible electric stepper motor than provided by feeder mechanisms that operate the stepper motor in only one direction. The sheet feeding assembly reliably feeds various types of media to marking devices or imaging devices without the need for an elevating plate mechanism or a solenoid operated nudger roll.
These and other objects, advantages and salient features are described in or apparent from the following detailed description of exemplary embodiments.
Exemplary embodiments will be described with reference to the drawings, wherein like numerals represent like parts, and wherein:
The sheet feeding assembly described herein is discussed in the context of a marking device, for purposes of illustration. However, the feeding assembly could be implemented in any type of marking device or imaging device, such as a printer, facsimile machine, scanner, or a xerographic marking device or any other device that feeds sheet material through a feed path.
A nudger roll 18 is connected to the support element 16 for rotation about a nudger axis, shown as B-B in
The sheet feeding assembly 10 may include a gear train assembly 20 intermediate the motor 24 and some or all of the feed roll 14, nudger roll 18, and rotary cam 22. The motor 24 may directly drive one of these elements, making a gear train assembly unnecessary for that element. The feed roll 14 and nudger roll 18 each have a surface suitable for engaging the surface of a sheet of media, such as may be required to slidably remove a sheet of media from the stack of media. The feed roll 14 or nudger roll 18 may include single or multiple rollers or coaxially mounted wheels or conveying belts for moving single sheets of media.
As shown in
When the motor 24 is operated in a reverse direction as shown in
The gear train assembly may comprise a first one-way clutch connected to the nudger roll and a second one-way clutch connected to the feed roll. A third one-way clutched gear 33 may be connected to the camshaft 34 which is directly connected to the cam 22. The camshaft 34 is also connected to a further one-way clutch housing 37, which is shown in
The cam 22 is profiled to move the nudger support element 16 and nudger roll 18 between an up position suitable for loading media onto the stack of media, shown in
An exemplary profile of the cam 22 is shown in
An exemplary cam 22 and one-way clutched gear are illustrated in
The sheet feeding assembly 10 may further comprise a biasing member (not shown) for biasing the nudger support element 16 and the nudger roll 18 toward the down position. The biasing may be of a form well-known in the art, such as but not limited to a spring.
The force applied by the biasing member may be tangential to the arc traveled by the nudger roll 18 as it travels between the up and down positions. The biasing force assists in maintaining contact between the nudger roll 18 and the top of the stack of media at a constant force, when the nudger roll 18 is in the down position. The cam 22 may be profiled to provide for the biasing force to assist in maintaining the cam in a stationary position when the nudger roll 18 is in the up position.
In this manner, it may be appreciated that during normal operation of the marking device or imaging device, the nudger roll 18 is in the down position on top of the media stack. The motor 24 operates in the forward direction to drive the nudger roll 18 to allow sheet feeding. The cam 22 is essentially disengaged and maintained in a stationary position. The cam 22 is rotated to the position shown in
The sheet feeding assembly 10 may be part of a document handling assembly for use with a marking device or imaging device, including a photocopier of the xerographic type or other such type of printer, facsimile machine or scanner. For a general understanding of marking device, such as an electrophotographic printer, solid ink printer or copying machine, or an imaging device, such as a scanner, the exemplary embodiments according to this disclosure may be incorporated, reference is made to
The exemplary marking device 41 shown in
The exemplary marking device 41 provides for the transfer of four color toners (yellow, magenta, cyan and black) from a plurality of toner cartridges 44 onto a transfer belt 45. The sheet of media is transferred along the feed path 43 by a plurality of transfer rolls 46 in turn between the transfer belt 45 and one of two primary transfer rolls 47 and further between a pair of fixing rolls 48 brought into abutting contact with each other, and then delivered out of the housing of the marking device 41. The color toners are applied to the sheet of media upon contact of the sheet with the transfer belt 45. The toners are subsequently fixed to the sheet upon contact with the fixing rolls 48.
The exemplary marking device 41 further comprises an exposure unit such as a laser light source arranged within the housing of the marking device 41 at a specified position in the housing to irradiate surfaces of a plurality of rotating electrophotographic photoreceptors 49 after charging with laser light emitted from the laser light source. This performs the respective steps of charging, exposure, development, primary transfer and cleaning in turn in the rotation of the electrophotographic photoreceptors. Toner images of the respective colors are then transferred onto the transfer belt 45, one over the other prior to application onto the sheet of media.
The exemplary document handling assembly has a sheet feed path extending from an input tray containing a stack of single sheet media to an output past a feed roll 14. A nudger roll 18 is provided for selectively engaging a sheet at the top of the stack of media and driving the sheet into the paper path. Operatively connected to the nudger roll 18 is a rotary cam 22 for operating the nudger roll to the top of the stack of media. The document handling system is also provided with a reversible electric stepper motor 24 and a gear train assembly intermediate the motor 24 and each of the feed roll 14, nudger roll 18, and rotary cam 22. The gear train transmits power from the motor 24 to rotate the feed roll 14 and the nudger roll 18 when the motor 24 is operated in a forward direction and to transmit power to rotate the rotary cam 22 when the motor 24 is operated in a reverse direction.
The memory 52 may serve as a buffer for information coming into or going out of the marking device 41, may store any necessary programs and/or data for implementing the functions of the marking system 41, and/or may store data at various stages of processing. The memory 52, while depicted as a single entity, may actually be distributed. Alterable portions of the memory 52 are, in various exemplary embodiments, implemented using static or dynamic RAM. However, the memory 52 can also be implemented using a floppy disk and disk drive, a writeable optical disk and disk drive, a hard drive, flash memory or the like. The links 58 may be any suitable wired, wireless or optical links.
The data sink 57 can be any device that is capable of outputting or storing processed data. The data source 59 can be a digital camera, a scanner, or a locally or remotely located computer, or any other known or later developed device that is capable of generating electronic image data. Similarly, the data source 59 can be any suitable device that stores and/or transmits electronic image data, such as a client or a server of a network. The image data source 59 can be integrated with the marking device or imaging device 41, as in a digital copier having an integrated scanner. Alternatively, the data source 59 can be connected to the marking device or imaging device 41 over a connection device, such as a modem, a local area network, a wide area network, an intranet, the Internet, any other distributed processing network, or any other known or later developed connection device.
The controller 51 may base the operation of the motor 24 on one or more input signals 53 such as a signal from a position detector for the rotary cam 22. The position detector may be of any type known in the art such as a photo-interrupt sensor. In embodiments, a photo-interrupt sensor detects the rising edge of the integral vane 22a of the cam as it is rotated by the motor 24.
An additional input signal 53 may be provided in the form of a detector for the stack height of the stack of media. This detector may determine when there is a need to add media to the stack; at which point the controller 51 may place the nudger roll 18 in the up position by selectively operating the motor 24 in a reverse direction.
A one or more one-way clutched gear may also be provided to restrict rotation of the feed roll 14 and/or the nudger roll 18 when the motor 24 is operated in a reverse direction. An additional one-way clutched gear may be provided to restrict rotation of the cam 22 when the motor 24 is operated in a forward direction. The rotary cam 22 is profiled to allow the adjustment of the nudger roll 18 from a down position in which the nudger roll 18 contacts the top of the stack of media to an up position in which the distance between the nudger roll 18 and the top of the stack of media is suitable for loading media onto the stack of media.
The method may provide that when the nudger roll is being driven, the nudger roll 18 is maintained in a stationary position, which may be accomplished by restricting the rotation of the rotary cam. A controller may further be provided for a step of controlling the operation of the motor based on one or more input signals such as from a rotary cam position detector. The rotary cam position detector assists in coordinating the operation of the sheet feeding system and may be provided in the form of a photo-interrupt sensor.
It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also, various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.
