PREVENTING MEDIA MISALIGNMENT DURING ACCUMULATION
In one example in accordance with the present disclosure a system for preventing media misalignment during accumulation. The system includes a number of media clamps having multiple positions to prevent misalignment of an incoming media sheet during accumulation. The number of media clamps are in a raised position after a leading edge of the incoming media sheet has passed over a trailing edge of the stack region. The media clamps are in a clamped position after the leading edge of the incoming media sheet has passed the media clamp.
Printing systems are used to deposit printing fluid such as ink, onto a print medium such as paper. After the print medium has been printed on, additional operations such as stapling, collating, offsetting a stack, and other post-printing operations may be performed on a stack of printed media.
The accompanying drawings illustrate various examples of the principles described herein and are a part of the specification. The illustrated examples are given merely for illustration, and do not limit the scope of the claims.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.
DETAILED DESCRIPTIONAs described above, printing systems are used to deposit a printing fluid such as ink, onto a print medium such as paper. Other examples of print fluids include three-dimensional print agents, bio-fluids, pharmaceutical agents, etc. Other examples of print medium include three-dimensional printing medium such as powder. After a printing system has deposited the ink onto the print medium, a finishing system that may be separate from, or integral with, the printing system executes finishing operations such as, but not limited to, aligning the stack, offsetting the media sheets, and stapling the media sheets together. While these finishing systems are useful at performing such operations, they are less efficient in some scenarios.
For example, during finishing operations, it is desirable for both the long and short edges of the media to be well-aligned to accommodate those finishing operations. Accordingly, a finishing system, which again may be separate from or integral with a printing system, should have sufficient control over a media sheet to be able to move the media sheet along multiple axes to align the edges and to maintain this alignment for subsequent operations. Such operations are difficult and become even more difficult when working with certain media, such as undried or partially-dried media.
For example, media with undried or partially-dried printing fluid may distort due to the expansion of fibers in the media. The expansion of these fibers causes curl and cockle in the print medium. Also, the presence of a printing fluid reduces the beam strength, i.e., the stiffness, of the media sheet such that it has a higher tendency to buckle under an applied force. Still further, as ink is deposited on the surface of the media sheet, the expansion of the paper fibers on the surface changes the surface properties which increases the surface frictional properties of the media sheet. Each of these conditions complicates the handling of media sheets that have been printed on with a printing fluid.
One specific complication is sheet curl that results as a sheet distorts due to the application of a printing fluid. If a previously printed sheet in a media stack has enough curl, an incoming media sheet may interact with the previously printed sheet and pull the sheet in the stack over on itself. Still further, if an incoming sheet collides with a previously printed sheet, the force of collision may pull the incoming media sheet out of a media transport device to result in either a moderate or significant misalignment of the incoming sheet. The misalignment in some cases causes a paper jam. If the trailing edge curl of the previously printed sheet is not so severe that collision with by an incoming sheet grossly misaligns the incoming media sheet, there still may be sufficient force on the incoming media sheet such that an x- and y-alignment as well as a z-axis rotation of the incoming media sheet is impacted; which again may result in a paper jam, or may have some other negative impact on job quality.
Yet another complication is that curled media sheets do not lay flat when stacked and thus create air cushions between sheets in a stack. This trapped air cushion lowers the sheet-to-sheet friction such that media sheets slide more easily relative to one another, impacting the ability to maintain stack alignment. The air cushions also increase the stack height reducing the capacity of the media support device.
Yet another complication is the alignment of incoming media sheets. For example, in some devices, a y-alignment, or an alignment along a transport direction of the media is performed by an alignment wall. As a media transport device releases the incoming media sheet, kinetic energy in the media sheet may cause the sheet to bounce off the alignment wall, pushing the media sheet away from the alignment wall. Such a pushing away may result in a misalignment in that direction or even a curl of the media sheet near the alignment wall.
Finishing systems have been devised to address incoming media sheet alignment. For example, in some finishing systems an incoming media sheet is ejected onto a previously accumulated stack. Before and during the ejection, the device may use a tapping action on two parallel edges of the media sheet to move the media sheet into the desired position and alignment in a single direction. Before or after this first alignment, a second operation is carried out to align the stack/sheet in a second direction. While this process may work for relatively flat media, it does not address the complications mentioned above that arise when dealing with an undried or partially-dried, and therefore non-flat, media. In other words, the present systems do not account for the effects of page curl, i.e., undried or partially-dried media, nor do they accommodate alignment of the undried or partially-dried media, which undried or partially-dried media have characteristics that do not lend well to the alignment described above. In fact, some finishing systems, rather than executing finishing operations on undried or partially-dried printing media, first dry the media and then perform the finishing operations. However, such drying equipment is costly and further lengthens the time to output of a job.
The present specification describes a system and method for preventing media misalignment during accumulation, particularly an undried or partially-dried media. Specifically, the present specification describes a device and method for controlling and maintaining an x-direction alignment and a y-direction alignment of a sheet printed by a fluid printing system. Doing so simplifies post-printing value-added operations such as stack alignment, stapling, offset, and other finishing operations. The systems and methods described herein also control edge curl so as to not impact the transport of an incoming media sheet in the finishing system.
The system includes a number of media clamps having multiple positions to prevent misalignment of an incoming media sheet during accumulation. The media clamps are in a raised position after a leading edge of an incoming media sheet has passed over the trailing edge of the stack region. The media clamps are then returned to an intermediate or a clamped position after the leading edge of the incoming media sheet has passed the media clamp to maintain control of the incoming media sheet.
The present specification also describes a method for preventing media misalignment of an incoming media sheet during accumulation. The method includes placing media clamps having multiple positions in a clamped position until a leading edge of an incoming media sheet has passed over a trailing edge of a stack region. The media clamps are then raised after a leading edge of the incoming media sheet has passed over a trailing edge of a stack region and then lowered after the leading edge of the incoming media sheet has passed the media clamp.
The present specification also describes a system for preventing media misalignment of an incoming media sheet during accumulation. The system includes a number of sets of media clamps having multiple positions. Each set of media clamps corresponds to a different media size and/or orientation and maintains alignment of an incoming media sheet when the incoming media sheet is of a corresponding size. When maintaining the alignment, a set of media clamps 1) are in a clamped position until a leading edge of the incoming media sheet has passed over a stack region of a media support device, 2) are in a raised position after the leading edge of the incoming media sheet has passed over a trailing edge of the stack region, 3) move to an intermediate position after the leading edge of the incoming sheet has passed by the media clamp and 4) return to the clamped position either before or during the secondary alignment process (y-alignment). The set of media clamps are in a raised position when an incoming media sheet is not of a corresponding media size.
Certain examples of the present disclosure are directed to systems and methods for preventing misalignment of an incoming media sheet that 1) prevents page jams; 2) prevents page defects such as bent or rolled edges or corners: 3) accommodates finishing for undried or partially-dried incoming media sheets; 4) maintains page alignment in a media support device; 5) simplifies post-printing operations; and 6) addresses page curl and cockle as well as alignment for a variety of media sizes. However, it is contemplated that the devices and methods disclosed herein may prove useful in addressing other deficiencies in a number of technical areas. Therefore the systems and devices disclosed herein should not be construed as addressing just the particular elements or deficiencies discussed herein.
As used in the present specification and in the appended claims, the term “stack region” refers to a portion of a media support device defined by where the media is to be accumulated. For example, the stack region may be a sheet sized portion of a media support device. The stack region may correspond to the page size for a particular print media.
Further, as used in the present specification and in the appended claims, a “y-direction” refers to a transport direction of the incoming media sheet. While specific reference is made to the y-direction, any direction may be implemented as a y-direction.
Still further, as used in the present specification and in the appended claims, an “x-direction,” “x axis,” or similar terminology refers to a direction or axis that is perpendicular to the y-direction or y-axis. The x-direction, y-direction, and a z-direction as well, are indicated in multiple figures.
Even further, as used in the present specification and in the appended claims, the term “raised position” refers to any number of positions that are not a clamped position. Within a raised position is any number of sub-positions. For example, an intermediate position is an example of a raised position as is a high position.
Yet further, as used in the present specification and in the appended claims, the term “a number of” or similar language is meant to be understood broadly as any positive number including 1 to infinity; zero not being a number, but the absence of a number.
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present systems and methods. However, the present apparatus, systems, and methods may be practiced without these specific details. Reference in the specification to “an example” or similar language indicates that a particular feature, structure, or characteristic described in connection with that example is included as described, but may not be included in other examples.
In the examples depicted in
As depicted in
The system (100) includes a number of media clamps (104), one of which is indicated in
As can be seen in
To prevent this misalignment due to page curl, the media clamp (104) may be in a clamped position until a leading edge of the incoming media sheet (102) has passed over the trailing edge (108) of the stack region (114). Doing so may reduce the page curl. In other words, media clamps (104) generate a reduced page curl (110-2) in a sheet of the stack (106). A reduced page curl (110-2) has less, if any, impact on the incoming media sheet (102) as the media sheet with the reduced page curl (110-2) has been moved out of the transport path of the incoming media sheet (102). The media clamps (104) also serve to compress the stack (106), removing extraneous air cushions between sheets of the stack (106) reducing the propensity for misalignment of the stack (106).
While
After, the incoming media sheet (102) has passed over the trailing edge (108) of the stack region (114), the media clamps (104) are moved to a raised position as depicted in
At some point after the alignment of the incoming media sheet (102), the media clamps (104) are returned to the clamped position as indicated in
While
This reduced amount of pressure and reduced height reduce the likelihood of stubbing and rolling over of the stack (106), but allow for movement of the incoming media sheet (102). Such a reduced height and pressure may be maintained during certain operations. For example, the media clamps (104) may remain in this intermediate position during an x-direction alignment of the incoming media sheet (102). In the present specification, an x-direction is perpendicular to the sheet transport direction (
The system (100) described herein includes media clamps (104) movable between multiple positions or heights allowing for enhanced finishing by addressing the difficulties in finishing undried or partially-dried incoming media sheets (102). More specifically, the media clamps (104) allow for accommodating undried or partially-dried incoming media sheets (102) that may have a greater propensity for misalignment and that exhibit page curl, which page curl may interrupt the media transport. While specific reference is made to the system (100) operating on partially-dried media, the system (100) may also be implemented to receive fully-dried media.
Once the leading edge of the incoming media sheet (
Once the incoming media sheet (
In returning to the clamped position, the system (
The method as described herein may allow for incoming media sheet (
Accordingly, each set of media clamps (104) can manage the alignment of an incoming media sheet (
As described above, the media clamps (104) maintain the alignment of the media stack (
Within a set of media clamps (104) each individual media clamp (104) may be individually controlled while moving down to the clamped position to allow equal contact of the media clamps (104) within a set on at least one of a media stack (
In addition to the individual media clamps (104) being independently controlled each of the sets of media clamps (104) are also independently controlled. For example,
The method (500) also includes receiving (block 502) at least a partially-dry incoming media sheet (
The media clamps (
The media clamps (
During a y-direction alignment of the incoming media sheet (
Returning to
Next, as depicted in
If contact is detected, the media clamp (104) is then incrementally raised as indicated in
Certain examples of the present disclosure are directed to systems and methods for preventing misalignment of an incoming media sheet that 1) prevents page jams; 2) prevents page defects such as bent or rolled edges or corners: 3) accommodates finishing for undried or partially-dried incoming media sheets; 4) maintains page alignment in a media support device; 5) simplifies post-printing operations; and 6) addresses page curl and cockle as well as alignment for a variety of media sizes. However, it is contemplated that the devices and methods disclosed herein may prove useful in addressing other deficiencies in a number of technical areas. Therefore the systems and devices disclosed herein should not be construed as addressing just the particular elements or deficiencies discussed herein.
The preceding description has been presented to illustrate and describe examples of the principles described. This description is not intended to be exhaustive or to limit these principles to any precise form disclosed. Many modifications and variations are possible in light of the above teaching.
Claims
1. A system for preventing media misalignment during accumulation, the system comprising:
- a number of media clamps having multiple positions to prevent misalignment of an incoming media sheet during accumulation, wherein the number of media clamps: are in a raised position after a leading edge of the incoming media sheet has passed over a trailing edge of the stack region; and are in a clamped position after the leading edge of the incoming media sheet has passed the number of media clamps.
2. The system of claim 1, wherein the number of media clamps are proximate the trailing edge of the stack region.
3. The system of claim 1, wherein the number of media clamps form a set selected from a number of sets of media claims, each set pertaining to a different media size.
4. The system of claim 1, wherein:
- a raised position comprises an intermediate position and a high position;
- the number of media clamps are in the high position after the leading edge of the incoming media sheet has passed over the trailing edge of the stack region; and
- the number of media clamps are in the intermediate position during an x-direction alignment of the incoming media sheet.
5. The system of claim 4, wherein the number of media clamps are in the intermediate position for a portion of a y-direction alignment of the incoming media sheet.
6. The system of claim 1, wherein the number of media clamps are in a clamped position until a leading edge of the incoming media sheet has passed over the trailing edge of the stack region.
7. A method for preventing misalignment of an incoming media sheet, the method comprising:
- placing media clamps having multiple positions in a clamped position until a leading edge of the incoming media sheet has passed over a trailing edge of a stack region;
- raising the media clamps after the leading edge of the incoming media sheet has passed over the trailing edge of the stack region; and
- lowering the media clamps to align the incoming media sheet with the stack region after the leading edge of the incoming media sheet has passed the media clamp.
8. The method of claim 7, further comprising:
- lowering the media clamps to an intermediate position during an x-direction alignment of the incoming media sheet; and
- lowering the media clamps to a clamped position for at least a portion of a y-direction alignment of the incoming media sheet.
9. The method of claim 7, wherein raising the media clamps comprises raising the media clamps to a high position after the leading edge of the incoming media sheet has passed over the trailing edge of the stack region.
10. The method of claim 7, further comprising receiving at least a partially-dry incoming media sheet.
11. The method of claim 7, further comprising calibrating an intermediate height of a set of media clamps relative to a media support device by:
- lowering the media clamps to an elevation lower than the media support device;
- translating the media support device towards the media clamps;
- detecting contact between the media support device and the media clamps;
- incrementally raising the media clamp and translating the media support device towards the media clamps until no contact is detected between the media support device and the media clamps; and
- once no contact is detected between the media support device and the media clamps, raising the media clamps a predetermined distance.
12. A system for preventing misalignment of an incoming media sheet, the system comprising:
- a number of sets of media clamps having multiple positions, each set of media clamps corresponding to a different media size, each set to: manage alignment of an incoming media sheet when the incoming media sheet is of a corresponding media size, wherein when managing alignment of an incoming media sheet, a set of media clamps: are in a clamped position until a leading edge of the incoming media sheet has passed over a stack region of a media support device; are in a raised position after the leading edge of the incoming media sheet has passed over a trailing edge of the stack region; and return to the clamped position to maintain an alignment of the incoming media sheet relative to the stack region; and be in a raised position when an incoming media sheet is not of a corresponding media size.
13. The system of claim 12, wherein a set of media clamps are aligned with the stack region of a corresponding media size.
14. The system of claim 12, wherein motion of media clamps within a set is independently controlled to allow equal contact of the media clamps within the set on at least one of a media stack and media support assembly.
15. The system of claim 12, wherein at least one set of media clamps is actuated by motion of a media transport assembly.
Type: Application
Filed: Dec 9, 2015
Publication Date: Feb 28, 2019
Inventors: Bruce G Johnson (LaCenter, WA), Elliott Downing (Vancouver, WA), Steve O Rasmussen (Vancouver, WA), Anthony W Ebersole (Vancouver, WA)
Application Number: 15/766,735