Patent Grant
7584953
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1. Field of the Invention
The present invention provides a media feeding apparatus. More specifically, the present invention provides an auto-compensating mechanism in combination with a step-spring for providing appropriate normal force throughout the feeding of a media stack.
2. Description of the Related Art
Various mechanisms have been utilized to feed media into a printer or other peripheral. Various of these mechanisms utilize a tray or bin in order to support a stack media in which the upper most sheet of the stack may be advanced to a processing station or printing area for printing by a laser printer or inkjet printer, for example. In typical printing or duplicating devices, individual sheets of print media are advanced from the media tray to the processing station by utilizing a paper picking device.
With media picking devices a critical relationship exists between the pick roller and the media stack. More specifically the relationship involves a normal force between the pick roller and the media stack. The normal force must be within an operating range for the pick or media feed process to work properly. When too much normal force exists, multiple sheet of media may be fed resulting in paper jams. When too little normal force exists, media will not feed into the printing area. Some devices utilize a spring loaded paper stack to provide the normal force for picking. Despite extensive tuning of this normal force, usually only a very narrow range of media weights will run reliably on these devices.
Feeding of print media sheets from a stack has been significantly improved by an auto-compensating mechanism (ACM) shown and described in U.S. Pat. No. 5,527,026, issued to Padget et al. which overcomes problems with obtaining proper normal force. Auto-compensating media feeders address prior art issues in media feeding. A pick roll is mounted on the rotating swing arm and rests on the media stack. When the pick roll drive gear is initiated through a gear located on the pivot shaft with the swing arm, a torque is applied to the swing-arm through a gear transmission. The torque rotates the swing arm and pick roll into the media stack. This generates a normal force which is dictated by the buckling resistance of the media being picked. The normal force is no more than is required to buckle a single sheet of media plus the friction resistance between the first and second sheets. When the upper most sheet has moved, the normal force automatically relaxes and, thus, the auto-compensating mechanism will not deliver more normal force than what is required to feed a single sheet of media.
In a C-path feeding system, the ACM is disposed in a generally horizontal position when the media tray contains a full stack of media at upper positions, close to the horizontal, the down force created by the ACM is not high enough to consistently feed the microporous media because the normal force provided by the ACM is low. As the media stack height decreases during operation, the ACM moves through its operating positions during which time the normal force increases. At lower positions, i.e. positions away from the horizontal, the down force is high enough to allow for sheet feeding of the microporous media and the like. These systems are critically affected by various media characteristics including, but not limited to, density, net weight, stiffness and smoothness of the media surface. For example, lightweight media is fairly easy to move from a media stack. However, as media thickness and weight have increased with increased photo printing, the difficulty with consistent feeding throughout a media stack has increased. Even more recently, print feeding difficulties have occurred due to the use of microporous photo paper. The high coefficient of friction between sheets of microporous media tends to remove the ACM from its range of operating torque. Increased down force of the ACM has not alleviated this problem throughout the media stack feeding.
Given the foregoing deficiencies, it will be appreciated that an apparatus is needed which allows consistent media feeding of many types of media.
A media pick assembly comprises a media tray for retaining a stack of media in a peripheral, an auto-compensating mechanism disposed adjacent to the media tray, the auto-compensating mechanism movable through an operating range including a starting angular position and an ending angular position, and a media biasing member engaging the auto-compensating mechanism and providing a discontinuous force on the auto-compensating mechanism through the operating range. The discontinuous force may act on the auto-compensating mechanism based on a position of the auto-compensating mechanism. The down force is applied in a limited portion of the operating range corresponding to a height of the stack of media in the media tray. The biasing member disengages the auto-compensating mechanism at a preselected position. The limited angular range is between about 0 degrees and about 25 degrees. The biasing member is a leaf spring or a coil spring. The assembly has a total down force by the auto-compensating mechanism and the discontinuous force by the biasing member is between about 2 and 4 milli-newtons. One end of the biasing member is connected to a structure inside of the peripheral. One end of the biasing member is connected to or in contact with the auto-compensating mechanism.
A media pick assembly comprises a printer, an auto-compensating mechanism within the printer which transmits torque to a media pick tire, the auto-compensating mechanism increasing down force on a media stack during operation through a preselected angular range, a biasing member having a first end and a second end, the first end engaging a stationary part of the printer, the second end engaging the auto-compensating mechanism, the biasing member applying a discontinuous force to the auto-compensating mechanism through a limited portion of the preselected angular range. The auto-compensating mechanism moves from a substantially horizontal position downward to a lower limit during the preselected angular range. The auto-compensating mechanism creates a down force which is proportional to resistance created between media sheets, the down force being greater when the media stack is low than when the media stack is high. The biasing member engages the auto-compensating mechanism when the media stack is high or above a preselected height to increase down force in the limited portion of the preselected angular range. The biasing member is connected to or engages with the auto-compensating mechanism. The biasing member is connected to an internal portion of the printer.
A media pick biasing assembly for a peripheral having an auto-compensating mechanism comprises an auto-compensating mechanism rotatably connected to a drive shaft, the auto-compensating mechanism having a range of motion associated with feeding of media from a media tray in the peripheral, a biasing member connected to the peripheral and engaging the auto-compensating mechanism, the biasing member applying a force on the auto-compensating mechanism through a preselected angular range of motion of the auto-compensating mechanism. The auto-compensating mechanism moving from a first position to a second position. The biasing member engages the auto-compensating mechanism within the preselected range of motion between the first position and the second position. The preselected range of motion is about 0 degrees to about 25 degrees. The biasing member is one of a leaf spring and a coil spring. The biasing member creates additional downward force for the auto-compensating mechanism within the preselected range and additional downward force is inhibited outside the preselected angular range.
A method of feeding media from a media stack into a peripheral device using an auto-compensating device, comprises applying a discontinuous force on said auto-compensating mechanism when said media stack is above a preselected height; feeding media from said input tray with said auto-compensating device; and discontinuing applying said discontinuous force on said auto-compensating mechanism when said media stack decreases to said preselected height during feeding of said media.
The above-mentioned and other 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:
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. 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 multiple functions such as scanning, copying, and printing 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.
Referring now in detail to the drawings, wherein like numerals indicate like elements throughout the several views, there are shown in
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The drive shaft 32 is substantially cylindrical in shape and comprises a gear 33 at one end. The gear 33 is operably engaged with a gear train (not shown) mounted on a transmission frame 25 within the printer portion 20. The transmission frame 25 may also function as a motor mount 27 wherein a motor (not shown) may be operably engaging the transmission gear train driving the ACM 30. At a side of the printer 20 opposite the frame 25, the shaft 32 is pivotally supported for rotation by the motor and transmission gear train (not shown). The drive shaft 32 may comprise a milled portion 60 for engagement of the ACM 30. By rotating the drive shaft 32, the milled portion 60 transmits torque to the ACM 30 and gears therein. Within the housing 34, the drive shaft 32 operates an ACM drive train 36 including at least one gear mounted on the shaft 32 inside the ACM 30.
At a first end of the drive train 36 is a drive shaft gear 38. The drive shaft 32 extends through the drive shaft gear 38 and is engaged therewith to transmit torque from the shaft 32 to the gear 38. In turn, this causes the ACM 30 to pivot in a counter-clockwise direction (as shown in
Adjacent the drive shaft gear 38 is a first idle or transmission gear 40. The first transmission gear 40 rotates about a shaft 41 extending through the ACM housing 34. The shaft 41 extends generally parallel to the drive shaft 32. The first transmission gear 40 is driven by the drive shaft gear 38 and drives a second transmission gear 42. In addition to rotating about shaft 41, the first transmission gear 40 orbits about drive shaft 32 as the ACM 30 moves through a stack of media from a first angle of operation to a second angle of operation. The first transmission gear 40 may have a number of teeth which is selected by one skilled in the art based on the angular velocity of the drive shaft 32 and the desired angular velocity at the pick tire 46.
Adjacent the first transmission gear 40 is a second transmission gear 42 which also rotates about a shaft 43 extending through the ACM housing 34. The shaft 43 is also generally parallel to the drive shaft 32. The second transmission gear 42 rotates about the shaft 43 and orbits about the shaft 32 and drive shaft gear 38. The second transmission gear 42 acts as a reversing gear to provide the desired rotational direction of the pick tire 46 relative to the tray 22. The desired rotational direction is determined by the direction of media feed required to move the media into the media feed path 21. Like the first transmission gear 40, the second transmission gear 42 has a number of teeth selected based on input angular velocity of the first gear 40 and the desired angular velocity of the pick tire 46.
Adjacent the second transmission gear 42 is a drive roller gear 44 which is operably connected to the drive roller or pick tire 46. The drive roller gear 44 and pick tire 46 are coaxially disposed upon a shaft (not shown) extending through the ACM housing 34 which is parallel to the shaft 32 as well as the shafts 41,43 for the first and second transmission gears 40, 42. The gear 44 rotates about the shaft as well as orbiting about drive shaft 32. As previously indicated, the input angular velocity of gear 42 and the number of teeth of gear 44 determine the output angular velocity of the gear 44 and pick tire 46. Because this angular velocity is known based on required speed of media in the media feed path 21, the characteristics for gears 40, 42 may be calculated, as will be understood by one skilled in the art.
Disposed above the ACM 30 is a step spring or biasing member 50. The spring or biasing member 50 may be utilized to force a component to bear against, to maintain contact with, to engage, to disengage, or to remain clear of some other component. The biasing member 50 is capable of storing energy when loaded and forced in one direction by the ACM and media M there below. As the ACM 30 operated and moves in the second direction, the member 50 is unloaded until it applies no force on the ACM 30. The biasing member has the characteristic of maintaining its ability to be loaded within operating loads. The exemplary biasing member 50 is depicted as a leaf spring however various elastic bodies and shapes may be utilized and substituted for the leaf spring design. For instance, the biasing member 50 may be, for example, a flat spring, a spiral spring or a helical spring. Flat springs include, but are not limited to, elliptical leaf or half-elliptical leaf springs. The helical springs are generally formed of round cross-section wire or the like and may include a compression or tension springs, as well as torsion and cone shaped springs.
The biasing member 50 is connected at an upper end to an adjacent structure of the printer 20 (not shown for purpose of clarity). The connection may be by fastener or by unitary connection such as a weld. Alternatively, the biasing member 50 may be connected to and extend from the housing 34 at one end, while free to engage some internal printer structure at the other end.
Because the step spring 50 is positioned above the ACM housing 34, as the ACM 30 moves toward a horizontal position, the free end of the step spring 50 engages the ACM housing 34. As a result, the flexed step spring 50 places a force on the ACM 30 which is substantially constant. As the ACM 30 rotates counter-clockwise during media feed, the down force increases due to the operation of the ACM 30. As the media stack height decreases during operation, the force applied by the step spring 50 remains generally constant until the spring force is disengaged from the ACM 30.
Referring now to
As depicted, line A depicts the normal force created by the ACM 30 without a step spring. During operation, the down force is greatest when the media stack is low. As the media stack M decreases in height, during media feeding, the torque increases such that additional spring force is not necessary. The media height is related to the position of the ACM 30 because the ACM 30 is close to a horizontal position when the media stack is high and angled from the horizontal as the height decreases during media feeding.
Beneath line A, line B depicts the force created by the step spring. The force is zero until the media height reaches a pre-selected position. In the present example, the paper height must reach six millimeters (6 mm) for the step spring 50 to engage. Once engaged, the step spring 50 increases its force on the ACM 30 until the height reaches another preselected height, for example about seven millimeters (7 mm) where the force becomes substantially constant. Between 6 mm and 7 mm, the spring 50 is loaded by engagement between the printer frame and ACM 30. Although these dimensions are provided, one skilled in the art should realize that these dimensions may vary based on the tray 22 capacity and position of the ACM relative to the tray 22. The spring force is discontinuous since at certain positions no force is applied by the spring 50 while at other positions the spring 50 does apply force to the ACM 30 thereby increasing the normal force applied by the ACM 30 to the media stack M.
Line C represents a summation of the normal force created by the ACM 30 and the step spring 50. The normal force is greatest at the end of the chart where the input paper stack is at its lowest. This is because the down force applied by the ACM 30 is high although the force applied by the spring 50 is zero. As the media stack height increases, the down force decreases until a jump in down force is exhibited around the six millimeter (6 mm) stack height, corresponding to Line B. As the media stack height increases, the normal force applied by the ACM 30 decreases but the force is higher than that force of Line A because of the increase in force caused by spring 50. The increase in down force of spring 50 maintains the total down force (spring 50+ACM 30) within a preselected operating range. According to the present exemplary embodiment, a range of operation for the normal force may be between 2 and 4 milli-Newtons. Although this may vary depending on the characteristics previously described. Further, since the spring 50 force is generally constant, curvature of Line C is generally parallel to Line A. At a position where the normal force would normally be outside its range of operation, the spring force of the step spring 50 increases the total normal force applied to the media so that the apparatus provides a normal force within an operable range even though the media stack continues to increase in height. Through this increase in normal force, the ACM 30 is kept within an operating range which is desirable and useful for various types of media.
Operation of the device is now described. Referring to
As drive shaft 32 rotates in a counter-clockwise direction, gears 40 and 42 rotate in their respectively proper directions so that the gear 44 and pick tire 46 turn in a clockwise direction for media feeding. Rotation of the drive shaft 32 causes the ACM 30 to create a down force until the upper sheet of media slips relative to the second sheet. When this slip occurs, the down force of the ACM 30 relaxes and a sheet of media is fed. In combination with the ACM 30, the biasing member 50 maintains enough down force on the ACM 30 from its horizontal position through a preselected angular position to keep the media feed operating properly.
Referring now to
Referring now to
Referring now to
Referring now to
In operation of the various embodiments depicted, one skilled in the art should understand that the media stack M is loaded into the media tray 22 causing the ACM 30 to rise to near an initial horizontal position. From this horizontal position or thereabouts, the discontinuous force is applied to the ACM 30 by the biasing element, for example, 50. As the media begins feeding, the ACM 30 moves from the initial position through an angular range to preselected position where the force on the ACM 30 is discontinued. Beyond the preselected position where the force is discontinued, and as the media continues to feed, the only down force is created by the torque of the drive shaft 32. When the media tray 22 is empty, a new stack of media is positioned in the tray 22 so that the ACM 30 rises to near a horizontal position and the discontinuous force is reapplied to the ACM 30.
The foregoing description of several embodiments and method 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.
| Number | Name | Date | Kind |
|---|---|---|---|
| 5527026 | Padget et al. | Jun 1996 | A |
| 5927703 | Endo | Jul 1999 | A |
| 7059596 | Iwase | Jun 2006 | B2 |
| 20040245704 | Hall et al. | Dec 2004 | A1 |
| 20050110206 | Hsieh | May 2005 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20080116627 A1 | May 2008 | US |
