Sheet stacker having movable arms maintaining stack quality

A sheet stacking apparatus includes a frame, a round member directly or indirectly connected to the frame, and an arm directly or indirectly connected to the frame. The arm is rotatable to rotate between a first position and a second position. The arm is positioned to bias sheets toward the round member when in the first position, and the arm is positioned to bias the sheets away from the round member when in the second position.

BACKGROUND

Systems and methods herein generally relate to sheet stacking devices and more particularly to sheet stacking devices that maintain stack quality.

Many flexible materials are available in sheet form, including print media, plastic sheeting, metallic sheets, foam materials, etc. It can be more efficient from a processing standpoint to stack these sheets during various stages of processing. In one example, after sheets of print media have received print markings, they are often stacked.

Stacking devices (stackers) are often used to perform such stacking operations. It is useful for such stacking devices to produce stacks in which all sheets lay flat and where the edges of all sheets are aligned. Many times, sheets are inverted just prior to being stacked; however, if the sheets do not fully complete the flipping process involved with inverting the sheets, this can result in sheets being folded under other sheets or in sheets irregularly piling upon one another.

SUMMARY

Various exemplary sheet stacking apparatuses herein include (among other components) a frame and at least one round member (e.g., disk), a first arm, a second arm, and a stacking surface (all directly or indirectly connected to the frame). A first hinge directly or indirectly connects the first arm to the frame and a second hinge directly or indirectly connects the second arm to the frame.

The round member is adapted to rotate, and the round member is positioned relative to the stacking surface to move the sheets toward the stacking surface when rotating. The first arm is rotatable around the first hinge to rotate the first arm between a first position (closed) and a second position (open). The second arm is similarly rotatable around the second hinge to rotate the second arm between a third position (closed) and a fourth position (open).

The second arm is longer than the first arm and extends closer to the stacking surface than the first arm when the first arm is in the first position (closed) and the second arm is in the third position (closed). The round member has leading edge receivers adapted to accept leading edges of the sheets, and the first arm is positioned to direct the leading edges of the sheets into the leading edge receivers of the round member when the first arm is in the first position (closed).

Thus, the first arm is positioned to bias the leading edges of the sheets toward the round member when in the first position (closed), but the first arm is positioned to bias the trailing edges of the sheets in a direction approximately parallel to the stacking surface when in the second position (open). Similarly, the second arm is positioned to bias the sheets toward the round member when in the third position (closed), but the second arm is positioned to not bias the trailing edges of the sheets toward or away from the round member to allow the sheets to lift off the round member when in the fourth position (open).

Additionally, a processor can be directly or indirectly connected to the first hinge and the second hinge. The processor is adapted to control the first hinge to only rotate the first arm to the second position (open) for a first type of sheet (e.g., lower beam strength sheets). However, the processor is adapted to control the second hinge to rotate the second arm to the fourth position (open) for both the first type of sheets and a second type of sheets (the first type of sheets have a lower beam strength relative to the second type of sheets). Further, a sensor can be directly or indirectly connected to the processor. The sensor detects whether the sheets are the first type of sheets or the second type of sheets. For example, the sensor (which can be, or include, multiple sensors of different types) can automatically detect the length of the media, the weight of the media, the humidity, temperature, and/or other environmental conditions within the stacking device, etc.

In greater detail, the first arm is rotatable around the first hinge to position the first arm in the first position (closed) when contacting the leading edges of both the first type of sheets and the second type of sheets. However, the first arm is rotatable around the first hinge to position the first arm in the second position (open) only when contacting the trailing edge of the first type of sheets; and the first arm does not rotate around the first hinge, but maintains the position of the first arm in the first position (closed), when contacting the trailing edge of the second type of sheets.

With respect to the second hinge, the second arm is rotatable around the second hinge to position the second arm in the third position (closed) when contacting the leading edges of both the first type of sheets and the second type of sheets. However, the second arm is rotatable around the second hinge to position the second arm in the fourth position (open) when contacting the trailing edges of both the first type of sheets and the second type of sheets.

Various sheet stacking methods herein include a number of steps, some of which include rotating the first arm around the first hinge to rotate the first arm between the first position (closed) and the second position (open). The first arm is positioned to bias sheets toward the round member when in the first position (closed). The first arm is positioned to not bias the sheets toward the round member when in the second position (open). The round member has leading edge receivers adapted to accept leading edges of the sheets, and the first arm is positioned to direct the leading edges of the sheets into the leading edge receivers of the round member when the first arm is in the first position (closed).

This processing also rotates the round member. The round member is positioned relative to the stacking surface to move the sheets toward the stacking surface when rotating. The process of controlling the first arm can control the hinge to position the arm to allow the trailing edge of a sheet to move from the round member in a direction approximately parallel to the stacking surface when the arm is in the second position (open).

In greater detail, in this processing, the first arm is rotated to the first position (closed) and the second arm is rotated to the third position (closed) when contacting the leading edges of both the first type of sheets and the second type of sheets. However, the arms operate differently on the trailing edges. Specifically, the first arm is rotated to the second position (open) only when contacting the trailing edge of the first type of sheets; and the first arm does not rotate, but maintains the first position (closed), when contacting the trailing edge of the second type of sheets. With respect to the second arm, in contrast the second arm rotates to the fourth position (open) when contacting the trailing edges of both the first type of sheets and the second type of sheets.

DETAILED DESCRIPTION

As mentioned above, when sheets are being inverted just prior to being stacked, if the sheets do not fully complete the flipping process, this can result in sheets being folded under other sheets or in sheets irregularly piling upon one another. The present inventors have found that different beam strength sheets will suffer from such problems differently.

More specifically, the present inventors have found that when longer length media, lighter weight media, and/or higher humidity condition are present, such conditions can reduce the relative beam strength of the sheets. These lower beam strength conditions can result in the trailing edge of the sheets not properly unfolding or uncurling, which may cause the trailing edge to not travel fully to the trailing end of the stacking surface, preventing the sheet from lying flat stacking surface. This can reduce the stack quality because some sheets may be folded under other sheets or other sheets may be irregularly piled upon one another. In contrast, with devices that produce high stack quality, all the sheets lie flat and the edges of such sheets are all aligned with one another.

In view of this, the devices and methods described herein use multiple arms, between which the sheets pass, to compensate for relatively low beam strength sheets. One of these arms (a first arm) is only rotated open for the trailing edges of sufficiently low beam strength sheets to help those sheets flip. Another of these arms (a second arm) rotates open for the trailing edges of both the lower and medium beam strength sheets. For sufficiently high beam strength sheets, neither arm may open when the trailing edges pass between the first and second arms. In contrast, to help direct the leading edges of sheets into a rotating disk that performs the flipping (inversion) process, both arms always remain closed for all leading edges of all sheet beam strengths.

FIGS. 1-5Dillustrate examples of such sheet stacking apparatuses herein. As shown inFIGS. 1-5D, these devices include (among other components) what is generically referred to herein as a “frame”110. The frame110can comprise many different components of the apparatus, which are elements of the apparatus and which are directly or indirectly connected to each other. Thus, the frame herein can include any or all of the various elements that physically support the enumerated components discussed below. In the attached drawings, identification numeral110is used to indicate the different items that can be considered this generically defined “frame.” All the individual components discussed below are in a fixed location (even though many of the following components move, rotate, etc., in their fixed locations relative to the frame110) and therefore all the following components are directly or indirectly connected to the frame110in some way.

With greater specificity,FIG. 1is a perspective view drawing that shows a stacking system100(apparatus, device, etc.) that includes a paper feeder device104that moves sheets102toward a curved paper guide106. The paper feeder device104and/or the curved paper guide106can include elements that move and control the sheets102including, roller nips, belts (vacuum and/or friction), rollers, slides, alignment guides, sheet position sensors, etc. Such elements are known and are not discussed in detail to maintain reader focus on the salient elements herein.

As can be seen inFIG. 1, sheets102are moved by at least the paper feeder device104to the curved paper guide106, which inverts the sheets102and directs the sheets102to a rotational device120which completes the sheet flipping (inversion). The rotational device120accepts the leading edges of the sheets102, while spinning/rotating, to move the leading edges to the sheets102to leading end108A of a stacking surface108. The rotational device120does not accept the trailing edge of the sheet102, but instead allows the trailing edges of the sheets102to unfold (uncurl, flip, etc.) and fall toward a trailing end108B (opposite the leading end108A) of the stacking surface. This operation inverts the sheet102, relative to their position in the paper feeder device104, and creates a stack of the sheets102on the stacking surface108.

FIG. 2Ais a cross sectional drawing showing a portion of the stacking system100in greater detail. Specifically,FIG. 2Ashows that the rotational device120includes one or more disks124. The disk124is a round mechanical component that rotates and that can be hollow or solid, thin or thick, etc., with a rounded exterior; and, therefore can take the form of a cylinder, flat disk or wheel (thin or thick), etc. Multiple disks can be center-connected to a common axel which can be rotated by a motor or other device to rotate all disks124synchronously together.FIG. 2Aalso illustrates a pair of nip rollers112, one or more of which can rotate to drive the sheets102along the curved paper guide106.

As shown inFIG. 2A, the disk124can include slots, cavities, openings, etc., that are referred to generically as “leading edge receivers”122, and that are configured and shaped to receive the leading edges of sheets of media. As the rotational device120continuously rotates, the leading edge of the sheets102runs into the planar surface of a notched alignment structure114that is connected to the leading end108A of the stacking surface108. As shown inFIG. 1, the notched alignment structure114has notches that allow only the disks124to pass through the notched alignment structure114; however, the leading edges of the sheets102contact the remaining non-notched planar surface of the notched alignment structure114, stopping the sheets102on the stacking surface108and aligning the leading edges of the stacked sheets102along the planar surface of the notched alignment structure114. When the leading edge of the sheets102runs into the notched alignment structure114, this stops movement of the sheets102on the stacking surface108and pulls the sheets102from the leading edge receiver122. Note that while the drawings illustrate that the disks124have two leading edge receivers122, more or less leading edge receivers122could be included in each disk124.

While the structure shown inFIGS. 1-2Agenerally works very well with most media types, when longer length media, lighter weight media, and/or higher humidity condition are present and such reduces the relative beam strength of the sheets102, the trailing edge of the sheets102may not properly unfold or uncurl and may not travel fully to the trailing end108B of the stacking surface108, preventing the sheet102from lying flat stacking surface108. This is shown, for example, inFIG. 2Bwhere the sheet102is shown with a slight buckle (e.g., fold, S-shape, opposing alternating curve shapes (opposing arch shapes), etc.) when compared to the mostly uniform single continuous curved arch shape of the sheet102shown inFIG. 2A.

If the sheet102shown inFIG. 2Bdoes not fully unfold, the next sheet102will not have a flat surface upon which to lie, causing the next sheet102to also fold (or at least not lie flat) and the same can continue with the following sheets, eventually resulting in an irregular stack of sheets or a jam of multiple sheets irregularly piled together.

As shown inFIG. 2C, the structures and methods herein address this issue. More specifically, the present inventors discovered that the sheet102will undesirably buckle if the trailing edge102B of relatively low beam strength sheets continues to travel along trajectory (direction) T1because this trajectory T1forces/drives the trailing edge102B of the sheet102downward and more toward the stacking surface108, promoting the undesirable buckle shown inFIGS. 2B-2C. In contrast, the present inventors discovered that if the trailing edge102B of the sheet102can be directed to travel in a trajectory T2that is relatively more parallel to the stacking surface108(relative to trajectory T1) the undesirable buckle can be avoided for relatively low beam strength sheets.

The exemplary structures illustrated in the drawings cause the trailing edge102B of the sheet102to travel in the trajectory T2that is relatively more parallel to the stacking surface108(e.g., relative to trajectory T1). For example,FIG. 3Ais a partial and more detailed view of the structure shown inFIGS. 1-2Cand includes a first arm132and a second arm136, a first hinge130directly or indirectly connecting the first arm132to the frame110, and a second hinge134directly or indirectly connecting the second arm136to the frame110.FIGS. 3B-5Bshow how the structure shown inFIG. 3Aoperates with different sheet beam strengths to direct the trailing edge102B of the sheet102to travel in the trajectory T2that is relatively more parallel to the stacking surface108(e.g., by opening a first arm132as shown inFIG. 4Aand discussed below).

These “arms”132,136can be paddles, baffles, guides, bars, projections, etc., and have the ability to maintain or change the trajectory of the sheets102. The first arm132is rotatable around the first hinge130to rotate the first arm132between a first position (closed,FIG. 3B) and a second position (open,FIG. 5A, discussed below). The second arm136is similarly rotatable around the second hinge134to rotate the second arm136between a third position (closed,FIG. 3B) and a fourth position (open,FIG. 4A, discussed below). The second arm136can be longer than the first arm132and can extend closer to the stacking surface108than the first arm132when the first arm132is in the first position (closed) and the second arm136is in the third position (closed). The sheets102pass between the first arm132and the second arm136.

FIG. 3Bshows the same structure shown inFIG. 3Awith a generic sheet102that has been fed into one of the leading edge receivers122of the round member124. As can be seen inFIG. 3B, the sheets102pass between the first arm132and the second arm136when moving from the curved paper guide106, past the first and second arms132,136, to the stacking surface108.

InFIG. 3Bthe leading edge102A of the sheet102is shown within the leading edge receiver122. Additionally,FIG. 3Bshows that the first arm132is in the first position (closed) and the second arm136is in the third position (closed). Therefore, when the first and second arms132,136are closed they are positioned to direct the leading edge102A of the sheet102into the leading edge receivers122of the round member124(and this is the machine state maintained for all leading edges of all sheets).

As noted above, these structures generally work very well with most media types. However, when longer length media, lighter weight media, and/or higher humidity condition are present and such factors reduce the relative beam strength of the sheets, the trailing edge of the sheets may not properly unfold or uncurl, preventing the sheets from lying flat. In order to illustrate these situations and the unique way in which the structures and methods herein address these issues,FIGS. 4A-4Billustrate a sheet142having a relatively higher beam strength,FIGS. 5A-5Billustrate a sheet144having a relatively medium beam strength, andFIGS. 6A-6Billustrate a sheet146having a relatively lower beam strength (where medium beam strength is between high and low beam strengths).

More specifically,FIGS. 4A, 5A, and 6Aillustrate the processing state where the trailing edges142B,144B, and146B of the sheets142,144, and146have just lost contact with the round member124.FIGS. 4B, 5B, and 6Billustrate the processing state where the next sequential sheet has been fed into the leading edge receiver122of the round member124and where the trailing edges142B,144B, and146B of the sheets142,144, and146have almost fully (or fully) uncurled to lie flat on the stacking surface108or lie flat on top of other sheets that are on the stacking surface108.

In the realm of sheets, beam strength is known to mean, for example, the tendency for an unsupported sheet to maintain, or return to, a flat state. For purposes herein, beam strength is considered a sheet's own unsupported, unaided ability to unfold (uncurl) when released from a curved surface so as to return to a flat state on its own and without manipulation by external components. Higher beam strengths correspond to a greater ability to self-unfold or self-uncurl, while lower beam strengths correspond to the opposite. The beam strength will vary depending upon the weight (e.g., g/cm2), stiffness, length, etc., of the sheets, as well as the environmental conditions (humidity, temperature, etc.). Therefore, the very same sheet (same type, weight, length, etc.) may have a higher beam strength in one environment (e.g., lower humidity) and a lower beam strength in a different environment (e.g., higher humidity).

The distinction between a relatively lower beam strength sheet and a relatively higher beam strength sheet varies based upon the different environmental conditions, sheet conditions, machine conditions, user definition of stack quality, etc. Therefore, no absolute measures of beam strengths are presented here. Instead, broadly a relatively higher beam strength is higher than a relatively lower beam strength, with a medium beam strength being between the two.

Additionally, the relatively lower beam strength will, for a given machine and a given environment, produce stacking errors that are above a “stack quality standard” that may be established by an operator or may be industry standards. Therefore, when sheets of a specific brand, type, length, weight, etc., used in a specific stacking machine that is subjected to specific environmental conditions (e.g., humidity, temperature, etc.) results in stacking errors that are below a user's subjective expected “stack quality” standard, such sheets can be classified as relatively lower beam strength sheets. Correspondingly, sheets that do not result in such stacking errors or where the stack quality is above the minimum quality standard, under the same conditions, environment, machine, etc., are classified as relatively higher beam strength sheets. The classification of different lengths, weights, types, brands, etc., of sheets (for different environmental conditions) can be found empirically for each specific machine/environment or potentially from industry-standard records if such are established.

As shown inFIG. 3A, the first arm132is rotatable around the first hinge130and the second arm136is rotatable around the second hinge134to position both the first arm132and the second arm136in the closed position (first and third positions, respectively) when contacting the leading edges of all types of beam strength sheets (high, low, and medium beam strength sheets, all of which are represented generically inFIG. 3Ausing the identification number102). This positioning helps guide all leading edges102A of all sheets102into the leading edge receiver122of the round member124. However, different positions are utilized for the first and second arms132,136for the trailing edges of sheets that have different beam strengths, as shown in the following examples illustrated inFIGS. 4A-6B.

In a first example for relatively higher beam strength sheets142, shown inFIG. 4A, the first and second arms132,136are both left in the closed position (first and third positions, respectively) when the trailing edge142B of the higher beam strength sheets142passes between the first and second arms132,136. At this processing state shown inFIG. 4A, the leading edge of the sheet142A has already become firmly positioned against the notched alignment structure114, preventing the sheet142from sliding along, or moving horizontally relative to, the stacking surface108.

Maintaining the first and second arms132,136in the closed position as the trailing edge142B passes between the first and second arms132,136causes the trailing edge142B to be released from the surface of the disk124only after the trailing edge142B passes by the distal end of the longer second arm136(the distal end of the second arm136is the end furthest away from the second hinge134). However, this does not result in decreased stack quality because the relatively higher beam strength sheets142will have a relatively higher ability/tendency to return to a flat position (e.g., snap back to a flat position) and there is, therefore, no need to rotate either the first arm132or the second arm136to the open position for such higher beam strength sheets142. Allowing the first and second arms132,136to remain in the closed position for both the leading edge142A and the trailing edge142B of the higher beam strength sheets142reduces wear on the components and reduces energy consumption (energy is used to rotate the arms).

FIG. 4Billustrates the processing state where the next sequential relatively higher beam strength sheet142has been fed into the leading edge receiver122of the round member124and where the trailing edge142B of the previous sheet142has almost fully (or fully) uncurled to lie flat on the stacking surface108or lie flat on top of other sheets that are on the stacking surface108. Note that both the first and second arms132,136are in the closed position as the leading edge142A passes between the first and second arms132,136inFIG. 4B.

In a second example for relatively medium beam strength sheets144(relatively lower beam strength than sheets142), shown inFIG. 5A, the first arm132is left in the closed position (first position) but the second arm136is rotated around the second hinge134to the open position (fourth position) when the trailing edge144B of the medium beam strength sheets144passes between the first and second arms132,136to not apply any bias to the sheets. At this processing state shown inFIG. 5A, again the leading edge of the sheet144A has already become firmly positioned against the notched alignment structure114, preventing the sheet144from sliding along, or moving horizontally relative to, the stacking surface108.

Maintaining the first arm132in the closed position, but the second arm136in the open position, as the trailing edge144B passes between the first and second arms132,136causes the trailing edge144B to be released from the region of the roller nips112after the trailing edge144B passes by the proximal end of the longer second arm136(the proximal end of the second arm136is the end closest to the second hinge134) allowing the trailing edge144B to move away from the disk124. Note that inFIG. 5A, the medium beam strength sheet144separates from the region of the roller nips112a distance further away from the stacking surface108relative to when the higher beam strength sheet142separates from the surface of the disk124inFIG. 4A, creating a broader arc in the sheet144inFIG. 5A, relative to more narrow arc of the sheet142shown inFIG. 4A. This broader arc helps prevent the relatively medium beam strength sheet144sheet from the folding shown inFIG. 2B, thereby maintaining high stack quality even for medium beam strength sheets144.

The processing state shown inFIG. 5Atherefore does not result in decreased stack quality because the medium beam strength sheets144will have a relatively medium ability/tendency to return to a flat position (e.g., snap back to a flat position) and there is, therefore, no need to rotate both the first arm132and the second arm136to the open position for such medium beam strength sheets144because only rotating the second arm136to the open position is sufficient for medium beam strength sheets144. Allowing the first arm132to remain in the closed position for both the leading edge144A and the trailing edge144B of the medium beam strength sheets144reduces wear on the components of the first arm132and reduces energy consumption; however, rotating the second arm136to the open position for medium beam strength sheets144prevents irregular stacking and stacking jams, thereby maintaining the user-established stack quality.

Again,FIG. 5Bagain illustrates the processing state where the next sequential relatively medium beam strength sheet144has been fed into the leading edge receiver122of the round member124and where the trailing edge144B of the previous sheet144has almost fully (or fully) uncurled to lie flat on the stacking surface108or lie flat on top of other sheets that are on the stacking surface108. As shown inFIG. 5B, the second arm134has been rotated back to the closed position for the next sheet so that both the first and second arms132,136are in the closed position as the leading edge144A of the next sheet144passes between the first and second arms132,136to ensure the leading edge146A is fed into the leading edge receiver122of the round member124.

In a third example for relatively lower beam strength sheets146(relatively lower beam strength than sheets144) shown inFIG. 6A, the first and second arms132,136are both rotated to the open position (second and fourth positions, respectively) when the trailing edge146B of the lower beam strength sheets146passes between the first and second arms132,136. At this processing state shown inFIG. 6A, the leading edge of the sheet146A has already become firmly positioned against the notched alignment structure114, preventing the sheet146from sliding along, or moving horizontally relative to, the stacking surface108.

Rotating the first and second arms132,136to the open position as the trailing edge146B passes between the first and second arms132,136causes the trailing edge146B to be released from the region of the roller nips112after the trailing edge144B passes by the proximal end of the longer second arm136and to be pushed (redirected) away from the disk124by the first arm132in a trajectory (e.g., T2) that is approximately (e.g., within 20% of) parallel to, or at least relatively more parallel to, the stacking surface108.

Movement of the trailing edge146B in trajectory T2is not hindered by the second arm136because it also is in the open position. Because the trailing edge146B is pushed away from the surface of the disk124by the first arm132, there is no decrease in stack quality even for relatively lower beam strength sheets146. More specifically, the force imparted by the open first arm132to the trailing edge146B is in a direction more parallel to the stacking surface108(e.g., horizontal direction) relative to the processing states shown inFIGS. 4A-5B(which allow the trailing edges142B,144B to move in a direction more perpendicular to the stacking surface108(e.g., more in a downward direction). This redirection of the trailing edge146B by the first arm132creates an even broader arc in the sheet146inFIG. 6A, relative to more narrow arcs of the sheets142and144shown inFIGS. 4A and 5A, respectively. This broader arc helps prevent the relatively lower beam strength sheet146from the folding shown inFIG. 2B.

Again,FIG. 6Billustrates the processing state where the next sequential relatively lower beam strength sheet146has been fed into the leading edge receiver122of the round member124and where the trailing edge146B of the previous sheet146has almost fully (or fully) uncurled to lie flat on the stacking surface108or lie flat on top of other sheets that are on the stacking surface108. Note that both the first and second arms132,136are rotated back to the closed position as the leading edge146A passes between the first and second arms132,136inFIG. 6Bto ensure the leading edge146A is fed into the leading edge receiver122of the round member124.

Therefore, the structures and methods herein address the issue of trailing edges of low beam strength sheets146not properly unfolding or uncurling by selectively opening the first and second arms132,136. Specifically, for sufficiently low beam strength sheets, not only does the second arm136open to allow the inherent uncurling/unfolding ability of the sheet146to move the trailing edge of the low beam strength sheet away from the round member124, the first arm132additionally pushes the trailing edge146B of the low beam strength sheet146away from the round member124in a trajectory approximately perpendicular to the stacking surface108. Thus, the force imparted by the open first arm132is in the direction relatively more parallel to the stacking surface108. In this way, the open first arm132provides additional force to the sheet's own uncurling and unfolding ability to combat the tendency of such low beam strength sheets146to fold or buckle, thereby maintaining high stack quality.

FIG. 7illustrates many components of printer structures204herein that can comprise, for example, a printer, copier, multi-function machine, multi-function device (MFD), etc. The printing device204includes a controller/tangible processor224and a communications port (input/output)214operatively connected to the tangible processor224and to a computerized network external to the printing device204. Also, the printing device204can include at least one accessory functional component, such as a user interface (UI) assembly212. The user may receive messages, instructions, and menu options from, and enter instructions through, the user interface or control panel212.

The input/output device214is used for communications to and from the printing device204and comprises a wired device or wireless device (of any form, whether currently known or developed in the future). The tangible processor224controls the various actions of the printing device204. A non-transitory, tangible, computer storage medium device210(which can be optical, magnetic, capacitor based, etc., and is different from a transitory signal) is readable by the tangible processor224and stores instructions that the tangible processor224executes to allow the computerized device to perform its various functions, such as those described herein. Thus, as shown inFIG. 7, a body housing has one or more functional components that operate on power supplied from an alternating current (AC) source220by the power supply218. The power supply218can comprise a common power conversion unit, power storage element (e.g., a battery, etc.), etc.

The printing device204includes at least one marking device (printing engine(s))240that use marking material, and are operatively connected to a specialized image processor224(that is different from a general purpose computer because it is specialized for processing image data), a media path236positioned to supply continuous media or sheets of media from a sheet supply230to the marking device(s)240, etc. After receiving various markings from the printing engine(s)240, the sheets of media can optionally pass to a finisher/stacker234which can fold, staple, sort, etc., the various printed sheets. The stacking system100discussed above can be included internally within the printing device204at any location where sheet stacking is needed, or externally as part of, for example, the finisher/stacker234. Also, the printing device204can include at least one accessory functional component (such as a scanner/document handler232(automatic document feeder (ADF)), etc.) that also operate on the power supplied from the external power source220(through the power supply218).

The processor224can be directly or indirectly connected to, and can automatically control, the paper feeder device104, the nip rollers112, rotational device120, etc. Additionally, the processor224can be directly or indirectly connected to, and can automatically control, the first hinge130and the second hinge134so that the processor224can control the rotation of the first arm132and the second arm136.

More specifically, the processor224is adapted to control the first hinge130to only rotate the first arm132to the second position (open) for trailing edges of low beam strength sheets146. However, the processor224is adapted to control the second hinge134to rotate the second arm136to the fourth position (open) for both the first type of sheets146and a second type of sheets142or144to not apply any bias to such sheets (again, the first type of sheets146have a lower beam strength relative to the second type of sheets142or144).

Further, as shown inFIG. 7, a sensor208can be directly or indirectly connected to the processor224. The sensor208can automatically detect whether the sheets102are the first type of sheets146or the second type of sheets142,144(or such information can be manually entered through the user interface212). For example, the sensor208(which can be, or include, multiple sensors of different types) can automatically detect the length of the media (media length sensor(s)), the weight of the media (media thickness/weight per area sensor), the humidity (hygrometer), temperature (thermometer), and/or other environmental conditions within the stacking device, etc.

The one or more printing engines240are intended to illustrate any marking device that applies marking material (toner, inks, plastics, organic material, etc.) to continuous media, sheets of media, fixed platforms, etc., in two- or three-dimensional printing processes, whether currently known or developed in the future. The printing engines240can include, for example, devices that use electrostatic toner printers, inkjet printheads, contact printheads, three-dimensional printers, etc. The one or more printing engines240can include, for example, devices that use a photoreceptor belt or an intermediate transfer belt or devices that print directly to print media (e.g., inkjet printers, ribbon-based contact printers, etc.).

FIG. 8is flowchart illustrating exemplary methods herein. The processing described herein may, in some situations, be more useful for longer sheets; and, therefore, sometimes the processing herein may not be performed for smaller sheets. This is reflected in item300inFIG. 8where the sheets length is compared to an established minimum sheet length and the following processing only occurs for sheets that exceed the previously established minimum sheet length.

When performed, this processing activates sheet movement components (e.g., the paper feeder device, the nip rollers, rotational device, etc.) in item301. The round member is positioned relative to the stacking surface to move the sheets toward the stacking surface when rotating in item301. Specifically, these methods rotate the first arm around the first hinge to rotate the first arm between the first position (closed) and the second position (open). The first arm is positioned to bias sheets toward the round member when in the first position (closed). The first arm is positioned to not bias the sheets toward the round member when in the second position (open). The round member has leading edge receivers adapted to accept leading edges of the sheets, and the first arm is positioned to direct the leading edges of the sheets into the leading edge receivers of the round member when the first arm is in the first position (closed). The process of controlling the first arm can control the hinge to position the arm to allow the trailing edge of a sheet to move from the round member in a direction approximately parallel to the stacking surface when the arm is in the second position (open).

Therefore, as shown in item302inFIG. 8, in this processing, the first and second arms are kept closed when contacting the leading edges of both the first type of sheets and the second type of sheets. However, the arms operate differently on the trailing edges.

Specifically, as shown in item304, for the trailing edge of sufficiently high beam strength (higher beam strength) sheets, this processing leaves both arms closed and processing returns to item302to await the leading edge of the next sheet. Alternatively, in item306, for the trailing edge of sufficiently low beam strength (lower beam strength) sheets, this processing rotates both arms to the open position. In another alternative, in item308, for the trailing edge of beam strength sheets that are between the higher and lower beam strengths (medium beam strength) this processing leaves the first arm closed, but rotates the second arm to the open position.

While item304immediately returns to processing the leading edge of the next sheet, because items306and308have rotated at least one arm to the open position, in item310this processing closes any open arms for the next sheet and returns processing to item302.

Therefore, with the methods herein, the first arm is rotated to the second position (open) only when contacting the trailing edge of the lower beam strength sheets (first type of sheets) as shown in item306; and the first arm does not rotate, but maintains the first position (closed), when contacting the trailing edge of the second type of sheets (medium and high beam strengths) as shown in items304and308. With respect to the second arm, the second arm rotates to the fourth position (open) when contacting the trailing edges of both the first type of sheets306and the second type of sheets308and may only remain closed when contacting the highest beam strength sheets in item304.

Herein, terms such as “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, “upper”, “lower”, “under”, “below”, “underlying”, “over”, “overlying”, “parallel”, “perpendicular”, etc., used herein are understood to be relative locations as they are oriented and illustrated in the drawings (unless otherwise indicated). Terms such as “touching”, “on”, “in direct contact”, “abutting”, “directly adjacent to”, etc., mean that at least one element physically contacts another element (without other elements separating the described elements). Further, the terms automated or automatically mean that once a process is started (by a machine or a user), one or more machines perform the process without further input from any user. Additionally, terms such as “adapted to” mean that a device is specifically designed to have specialized internal or external components that automatically perform a specific operation or function at a specific point in the processing described herein, where such specialized components are physically shaped and positioned to perform the specified operation/function at the processing point indicated herein (potentially without any operator input or action). In the drawings herein, the same identification numeral identifies the same or similar item.