BACKGROUND

[0001] Modern printing and copying machines are very complex products with numerous features desired by customers. Printers output paper or other print media, with multiple sheets accumulating in a stack or pile.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] The accompanying drawings illustrate various examples of the principles described herein and are a part of the specification. The illustrated examples are exemplary in nature and do not limit the scope of the claims. Like numerals denote like but not necessarily identical elements.

[0003] FIG. 1 shows an example of a system according to the present disclosure.

[0004] FIGS. 2A-E show example geometries for the end stop according to the present disclosure.

[0005] FIGS. 3A-B show example end stops according to an example of the present disclosure.

[0006] FIG. 4 shows an example of a system according to the disclosure.

[0007] FIG. 5 shows a side view of a system according to the disclosure.

[0008] FIG. 6 shows an overhead view of a system according to the disclosure.

[0009] FIG. 7 shows a flowchart with a method according to the disclosure. DETAILED DESCRIPTION

[0010] Printing devices such as printers and copiers have a large number of quality characteristics that they may meet in order to satisfy customer expectations. One desired feature is that output materials are stacked in a neat manner such that the successive sheets are aligned with the lateral and longitudinal variation minimized over the stack depth. This may allow enhanced use of automation in subsequent operations, such as stapling, binding, etc. This may reduce the probability of paper jams or similar faults that may involve additional human intervention. Poor output stack alignment can lead to custom dissatisfaction, difficulty collecting print jobs, extra time used to align the stack for finishing, and even pages on the floor.

Accordingly, it is desirable for a printing device to output sheets in an orderly stack. Some variables that can affect output stack alignment include: eject speed, sheet to sheet friction, environment conditions, paper stiffness, paper weight, paper size, the printed image, amount of ink on the page, and the output bin geometry.

[0011] Another quality characteristic of printers is printing speed. Printing systems with higher page per minute (ppm) printing rates are valued by customers due to the increased throughput. Because print speed is quantified, it may be used to compare printing devices. Printing speed is a function of velocity of the printing medium as it travels through the device. Printing speed may be roughly proportional to the velocity of the printing medium within a printing system. Additionally, the length of the path of the print material may have a small impact on startup and completion time. As the velocity of the print medium increases, the exit velocity and kinetic energy of the ejected medium also increases. This kinetic energy is dissipated by the print medium in order for it to stop moving and settle into position in the output stack. As the kinetic energy of the print media increases, it may be increasing difficult to obtain alignment between successive sheets of the print media in a print job. Thus, increasing printer throughput makes it more difficult to obtain aligned output. [0012] The following examples teach methods, devices, and systems that align the print media with relatively high print speeds. The provided examples are non-limiting and intended to instruct persons of ordinary skill in the art how to make and use the claimed products.

[0013] FIG. 1 shows an example of an output system for aligning output materials according to the present disclosure. The sheet (100) is ejected from a system (1 10), for example, a printer or photocopier, but functionally any system that is designed to handle sheets. The sheet (100) is ejected from the system toward the end stop (120). The end stop (120) is situated such that the sheet (100) contacts it. The end stop (120) then absorbs a portion of the kinetic energy associated with the sheet (100). Similarly, the sheet (100) may flex and store some of the kinetic energy. Further, the leading edge of the sheet (100) may follow a sloped surface on the end stop (120) upwards, storing a portion of the kinetic energy as potential energy. Many variations of geometry of the contact portion of the end stop (120) with the sheet (100) can be applied to produce the desired result, which is, to redirect the motion of the sheet (100) at an angle to the original direction (130). For example, the end stop (120) may be angled with respect to the leading edge of the sheet (100) as the sheet enters the stacking area. The redirected direction (140) is selected so as to include a component lateral (perpendicular) to the original direction (130) of the sheet. Thus, if the original sheet was advancing in a direction X (130), with its leading edge straight in a Y direction that is 90 degrees from X, the second direction (140) would include a component in the Y direction. Thus, the first (130) and second (140) directions are not parallel or antiparallel.

[0014] Sheets (100) may be any of a wide variety of materials that can be processed by handling equipment. Examples of sheets include paper, textiles, and polymer films. Print media or medium refers to materials and geometries that can be printed on. This printing can be performed using a variety of techniques including thermal ink jets (TIJ), piezoelectric ink jets (PIJ), presses, and similar automated or semi-automated techniques.

Examples of print media include paper, textiles, and polymer films. [0015] The end stop (120) may be integrated with other components or may be stand alone. For instance, the end stop (120) may be part of a molded assembly or may attach to a molded assembly. The end stop (120) can be constructed of any suitable material including polymers, especially industrial polymers such as polyurethanes (PU), polycarbonate (PC), polystyrene (PS), polyoxymethylene, and polyether ether ketone (PEEK); composites, ceramics, or metals, such as stainless steel, titanium, and spring steel. Due to the wide variety of suitable materials, material choice may depend largely on other considerations such as cost, durability, machinability, appearance, etc. Transparent materials allow easier visual assessment of stack height. Similarly, the end stop (120) may include cutouts or windows, which may aid in observing stack height.

[0016] The end stop (120) may be adjustable to multiple positions. The positions may correspond with different sizes of sheets (100), such as letter, legal, A3, A4, etc. For example, the end stop (120) may be adjustable to three positions according to size of sheets used; letter, A4 and legal. The angle of the end stop (120) may be adjustable over a range of angles.

Alternately, a portion of the end stop (120) and/or the whole end stop (120) can be swapped out and/or adjusted.

[0017] FIGS. 2A-E show example geometries for the end stop (120) according to the present disclosure. This is not an exhaustive list but rather intended to inform one of ordinary skill in the art of a wide variety of possible approaches covered by the claims.

[0018] FIG 2A shows a version of the end stop (120) that employs a pin (210) fixed so as to asymmetrically contact the sheet (100). As a result, the side of the sheet (100) contacting the pin (210) will deform more and store more energy for release producing the desired deflection. While the pin (210) could have a round cross section, as shown, a wide variety of cross sections geometries are similarly workable, including, but not restricted to, squares, rectangles, triangles, polygons, curves, ovals, semicircles, etc.

[0019] FIG. 2B shows an angled end stop (220). The angle produces a more uniform distribution of deflection over the leading edge of the sheet (100) but still concentrates the deflection on the where the sheet (100) first contacts the angled end stop (220). Lateral force transfer within the sheet may allow more energy to be more efficiently recovered than a simple pin (210). In some examples, the angle between the leading edge of the sheet (100) and the angled end stop (220) is between 1 and 20 degrees. In some examples, the angle between the leading edge of the sheet (100) and the angled end stop (220) is between 2 and 10 degrees. In some examples, the angle between the leading edge of the sheet (100) and the angled end stop (220) is between 4 and 8 degrees. In one example, the angle is

approximately 5 degrees.

[0020] An end stop (120) may be sloped in addition to angled. The end stop (120) may be sloped relative to vertical and/or relative to the stacking area. In some examples, the slope facilitates lifting a leading edge of the sheet (100). In some examples the slope produces lateral motion as the sheet (100) settles. A wide range of slopes can be accommodated depending on the specific geometry selected for the end stop. In some examples, the end stop is sloped between 91 and 160 degrees relative to the stacking area. In some examples, the end stop is sloped between 1 10 and 150 degrees relative to the stacking area. In some examples, the end stop is sloped between 120 and 140 degrees relative to the stacking area. Similarly, in some examples, the end stop is sloped between 1 and 60 degrees relative to vertical. In some examples, the end stop is sloped between 10 and 40 degrees relative to vertical. In some examples, the end stop is sloped between 20 and 30 degrees relative to vertical.

[0021] FIG. 2C shows an end stop constructed from multiple pins, the pins may provide a contact surface similar to the shown dashed contour (250). The use of pins or similar elements may have benefits in terms of access or visibility of the accumulating stack. However, the use of pins instead of a surface may also increases the local deformation of the sheet (100). [0022] FIG. 2D shows a combination end stop (230) with a flat portion (232) to distribute the force of the leading end of the sheet and an angled portion (234).

[0023] FIG. 2E shows a combination end stop (240) with a flat portion (232) and an angled portion (234) connected with a curve (242). The curve (242) helps reduce the discontinuity of the angle and provides a smoother distribution of stored energy and recoil forces that are applied to the sheet (100).

[0024] In one example, the contacting surface of the end stop (120) is made of two portions, each portion with a different stiffness such that one portion transfers more recoil than a second portion. For instance, a metal end stop could be cut with different width fingers from one side to the other to provide a range of stiffnesses across the contact surface. The end stop (120) may include solid forms, pins, or fingers of material depending on the material and geometry used. The end stop (120) may be located asymmetrically to the centerline of the sheet (100) perpendicular to the leading edge of the sheet (100). Alternately, some end stop (120) geometries, such as those with an angled portion may function in at both the centerline and/or an asymmetrical position.

[0025] FIGS. 3A-B show example end stops (120) according to an example of the present disclosure. FIG. 3A shows a sloped surface (300) of an end stop (120) according to an example of the present disclosure. Some portions of the end stop (120) may have a sloped sheet-contacting surface (300) such that as the sheet settles while contacting the end stop, lateral motion is imparted to the sheet.

[0026] FIG. 3B shows a sloped surface (300) of an end stop (120) according to an example of the present disclosure. This figure also includes a curved portion (310) near its base. The sloped surface (300) may be discrete from the curved portion (310). Alternately, the sloped surface (300) and the curved portion may be integrated to provide a smooth transition between them. [0027] Clearly, a wide variety of shapes and cross-sections can be used to form an end stop (120). Many different geometries can be used to create an end stop (120) that redirects the sheet (100) from a first direction (130) to a second direction, where the first and second directions are at an angle to each other.

[0028] FIG. 4 shows an example of a system according to the disclosure. Specifically, FIG. 4 includes both an end stop (120) and a side stop (400) to facilitate quality stack formation. The system (1 10) processing the sheets (100) ejects the sheet in a first direction (130). The sheet (100) contacts the end stop (120) and is redirected in a second direction (140). The sheet moves in the second direction (120) until contacting the side stop (400). As shown under FIG. 1 , the end stop (120) may be used independently. As shown in FIG. 4, the end stop (120) may also be used in conjunction with a side stop (400). Both approaches have been shown in development and testing to provide significantly improved stack quality.

[0029] The use of a side stop (400) provides a restriction on lateral movement of the sheet (100), helping to provide consistent positioning and improved stack quality. Note that unlike systems that place barriers or stops on both lateral sides of the sheet (100), a system that directs the sheet (100) against a single side stop (400) is not over constrained, which is to say its lateral position is determined by the position of the side stop. In contrast, a system with stops or barriers on both sides has to account for both side positions as well as the width of the sheet (100) when attempting to determine lateral position. The proper number of constraints on the lateral position contributes to reproducibility of the sheet (100) location. The use of a single side stop (400) eliminates the potential for the barriers being too close together resulting in bowing of the paper or being too far apart and encouraging scatter. Rather, scatter is deterred by the end stop and side stop barrier rather than two parallel stops.

[0030] The use of a single side stop (400) is effective because the end stop (120) provides lateral motion to assure reproducible contact with the side stop (400). Side stops (400) can incorporate a variety of geometries. [0031] The side stop (400) may be formed using similar materials and methods as the end stop (120). Indeed, the use of the same material and method may be selected to reduce costs or provide greater consistency in the appearance of the final product. Any functional combination of materials may be used for the end stop (120) and/or the side stop (400).

[0032] FIG. 5 shows a side view of a system according to the disclosure. The end stop (120) is visible opposite the stacking area (500) from the system (1 10). The sheet (100) is ejected toward the end stop, which redirects the motion of the sheet (100). The sheet (100) then contacts the side stop (400).

[0033] A stacking area (500) may be flat or inclined. The stacking area (500) may be inclined toward the end stop (120). The stacking area may be inclined away from the side stop (400). The stacking area (500) may be inclined away from the end stop (120).

[0034] Experimental work suggests a slope of the stacking area (500) toward the side stop of approximately 5 degrees facilitates improved stack quality. In some examples, the slope of the stacking area (500) toward the side stop (400) is between 1 and 20 degrees. In some examples, the slope of the stacking area (500) toward the side stop (400) is between 2 and 10 degrees. In some examples, the slope of the stacking area (500) toward the side stop (400) is between 4 and 8 degrees. In some examples the stacking area (500) is flat relative to the side stop (400).

[0035] Similarly, a slope of the stacking area (500) toward the end stop in the first direction may facilitate stacking. In some examples, the slope of the stacking area (500) toward the end stop (120) is between 91 and 160 degrees. In some examples, the slope of the stacking area (500) toward the end stop (120) is between 120 and 150 degrees. Similarly, in some examples, the slope of the stacking area relative to horizontal is between 1 and 45 degrees. In some examples, the slope of the stacking area relative to horizontal is between 5 and 30 degrees. In some examples, the slope of the stacking area relative to horizontal is between 10 and 20 degrees. [0036] In some cases, the end (120) and/or side (400) stops may be designed to retrofit existing equipment. In such cases, the geometry of the stacking area is often fixed and accommodated by the end (120) and/or side (400) stop designs. In other cases, the stacking area (500) may be replaceable or designed as part of a new device or system.

[0037] A stacking area (500) is the area where sheets are accumulated after exiting a system (1 10). A stacking area (500) according to the present disclosure includes an end stop (120). In some examples, the stacking area (500) is bounded by an end stop (120). In some examples, the stacking area is bounded by an end stop (120) and a side stop (400).

[0038] FIG. 6 shows an overhead view of a system according to the disclosure. The end stop (120) is angled so as to deflect sheets (100), coming from the right of the figure, toward the side stop (400). The stacking area (500) is shown and in this example includes a number of ridges (600). The ridges (600) may reduce the friction between the sheet (100) and the stacking area (500), facilitating alignment of the forming stack. In one example, ridges (600) run in the first direction of travel of the sheets (100). Ridges (600) may also run in more complex shapes, including curves, hatched patterns, etc. The ridges (600) need not be uniform over the stacking area (500) but may be more concentrated where the stack is located than in areas adjacent to where the stack is located. Ridges (600) may be placed so as to interact with a slope of the stacking area (500) and may include bumps, dots, retaining features, and/or guides to facilitate alignment of stacked sheets (100).

[0039] FIG. 7 shows a flowchart with a method (700) according to the present disclosure.

[0040] In operation 702, a sheet (100) enters the stacking area (500) traveling in a first direction (130).

[0041] In operation 704, the sheet (100) contacts the end stop (120) and is deflected in a second direction (140). The second direction (140) is at an angle to the first direction (130). The second direction (140) is not parallel or anti-parallel to the first direction (130). The second direction (140) contains a component that is perpendicular to the first direction (130).

[0042] In operation 706, the sheet (100) contacts the side stop (400). For example, the side stop (400) may bound the stacking area in the second direction.

[0043] Within the principles described by this specification, a vast number of variations exist. Accordingly, the specification supports and enables a wide variety of geometries.