Patent Application
20090315251
The present invention relates to a system and method for sheet feeding and, more particularly, to a system and method for sheet feeding that adjusts the feed timing based on information related to downstream sheet acquisition data.
Various feeding systems have been developed for media items, such as sheets of paper or envelopes, for example. Such systems may have applications in inserter systems, sorters, mailing machines, and other devices. Various applications require a particular spacing, i.e., gap, between the various media items being fed, such that a system's processing rate is maintained and downstream functions can be performed properly in relation to each media item being transported along a path of travel. Typically the media items are fed from a stack of media items onto a transport system for transport along the path of travel.
Conventional feeding systems are subject to factors that can cause variation of the feeding process and, thus, variation of the spacing between sequentially fed media items. These factors may relate to the operation of the feeders, such as wearing and/or degradation of parts. Other factors relate to the media item being fed, such as variation in the thickness of the item. Still other factors relate to environmental aspects, such as humidity, that can result in changes to the media or dirt and dust that can result in changes in the operation of the feeder. Some of these factors may occur over a short or long period of time, from job run to job run of the equipment, and/or other within a single job run of the equipment.
For example, in vacuum feeding systems feeding sheets of paper, factors that may cause variations in the feeding process can include the time it takes to open the valve to commence the vacuum build up, the time for the vacuum to build up to dimple the paper, slippage through the drive drum driving the paper forward, differences in the home position of the various servo motors, the stiffness of the paper, the position of the stripper bar, the roughness of the paper surface, the attachment of the paper to the feeder drum, the presence of paper dust or other materials that may adhere to moving components, humidity, water content of the paper, thickness of the paper, and orientation of the grain of the paper.
Similarly, drive roller feeding systems can also have a variation in the feeding process due to a range of factors, including many of those noted above. Other factors include changes in friction between the drive roller and the media being fed from the feeder and the friction provided by the retard stone or retard roller, as well as changes in the relative position of the drive roller and the retard stone or roller. The factors may cause variations in the feeding process depending on the type and implementation of the specific feeding system.
Variation in spacing of media items being fed seriatim from a feeder system can create problems in system productivity and in media item jams. If the spacing becomes too close between media items, jams may occur. For example, if a second media item is presented to a printing station early because of a smaller than desired gap between media items, a jam may occur with the preceding media item still at the printing station.
If the spacing becomes too large between media items, there may be a decrease in a system's productivity. For example, if a second media item is presented to a printing station late because of a larger than desired gap between media items, the printing station may be idle while waiting for the arrival of the media item. Both of these types of problems are not unique to printing stations, but relate to other types of stations that may be involved in the overall system. In some cases, the time to clear jams, a lower than desired feed rate, and idle time of the media item processing stations, such as printing, folding, collating, inserting, and envelope flapping stations, can negatively impact a system's productivity.
In the following description, certain aspects and embodiments of the present invention will become evident. It should be understood that the invention, in its broadest sense, could be practiced without having one or more features of these aspects and embodiments. It should also be understood that these aspects and embodiments are merely exemplary.
In some aspects of the invention, determining the time between initiating a feed cycle and when a media item is detected as being present at a particular point in the feeding system, such as a point in the feed path, may be employed to adjust the feeding process to help maintain a desired spacing, i.e., gap, between various media items being fed.
According to other aspects, the feeding process may be controlled for each media item being fed and, if necessary, adjusted to help maintain the desired spacing between successively fed media items by employing information as to the time between initiating a feed cycle for a preceding media item and when the preceding media item was detected as being present at a particular point in the feeding system.
In one embodiment, a method for feeding media items seriatim along a path of travel includes initiating a feed of a first media item along the path of travel and detecting the presence of the first media item along the path of travel. The time value is determined between initiating the feed of the first media item and detecting the presence of the first media item. The initiating of feed of a second media item along the path of travel is controlled based on the determined time value between the initiating the feeding of the first media item and the detecting the presence of the first media item.
In another embodiment, a system for feeding media items seriatim along a path of travel includes a media item transport and a support structure adapted to support a stack of media items to be fed seriatim from the support structure onto the media item transport. A media item feeder is operably connected to the support structure and to the media item transport. The media item feeder includes a mechanism which, when initiated to operate, is adapted to feed single media items from a stack of media items in the support structure onto the media item transport.
A detector is positioned in relation to the media item transport to detect the presence of a media item at a point on the media item transport. A controller is connected to the detector and to the media item feeder. The controller is operable to initiate the media item feeder to feed a single media item from a stack of media items in the support structure onto the media item transport based on a determined time value from the initiation of a feed onto the media item transport of an preceding media item, and on information from the detector relating to detection of the preceding media item in relation to an expected time value, whereby spacing on the media item transport between media items fed seriatim onto the media item transport is controlled.
Aside from the structural and procedural arrangements set forth above, the invention could include a number of other arrangements, such as those explained hereinafter. It is to be understood that both the foregoing description and the following description are exemplary only.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention. As shown throughout the drawings, like reference numerals designate like or corresponding parts.
Reference is now made to
The operation of the valve 20, as well as the feed motor 18 and a transport motor 26, are controlled by a controller 28 that provides control and program store for the feeder system 10. The system further includes a detector system 30, such as an optical detector, which is positioned along the transport path 14 to detect media items driven along the transport path 14. The media items, such as media item 36, are driven by the feed motor 18 driving feed drum 16, along with the transport motor 26 driving feed roller 32, which cooperates with idler roller 34, to cause a media item to be fed out from the media stack 12 and to be driven along the transport path 14.
Reference is now made to
Reference is now made to
Reference is now made to FIG. 4., where the first media item 36 and the second media item 38 are shown to have an improperly small spacing, indicated as the gap 42. This gap 42 is a smaller than desired gap. This situation can cause jams in the equipment as the media items move down the transport path 14 and/or are fed into various stations for processing the media items such as printing, folding, collation, insertion, flapping envelopes, etc. Correction of this gap situation is made by operation of the system of the invention in accordance with the flow chart shown in
Reference is made to
Reference is now made to
The program shown in
When the media item has arrived, at block 58, the valve 20 is closed. At block 60, the actual acquire time, that is, the time from initiation of the feeding of the media item until the media item is detected is either measured or calculated, as will be explained below. This determined time is the actual time to acquire the media item at a point in the system, such as a point on the transport path from the time of the initiation of the media item feed, which is measured and/or calculated by employing distance and velocity. For example, the rotational distance moved and velocity of movement of the feed drum motor 18 or the rotational distance moved and velocity of movement of the transport motor 26 can be utilized to calculate the acquire time from feed initiation until detection.
The determined time and the expected time can be measured or calculated. This is carried out by measuring time, distance, or a combination of both time and distance, and employing appropriate calculations. The terms “determining time value,” “determined time value,” “determining expected time value,” and “expected time value,” as used herein, are each intended to include and cover measuring time and/or distance and making any calculations to establish the value. The term “expected value” also further includes and covers a predetermined expected time that may be employed in the operation of the feeder system.
A determination is then made at decision box 62 if the acquired time is early by comparing it against the expected time. If the acquired time is not early, a determination is then made at decision block 64 if the acquired time is late by comparing it against the expected time. If the acquired time is not late, the system loops back and a determination is made at decision block 66 if the minimum time to the next feed has been completed. The expected time can be a predetermined value or one that is calculated based on known factors that affect the expected time, such as the velocity of the feed or transport motor or the travel distance of the motor after feed. If the minimum time to the next feed of a media item has been completed, the system continues to decision block 52. If this is not the case the system loops back.
As discussed above, the expected time can be a predetermined time value. The expected time can also be represented by the movement of a part from one point to another point. The expected time is thus essentially calculated by known factors of velocity (e.g., inches per second) and distance (e.g., inches). Examples of moving parts that may be used for representing the expected time are (1) the velocity of a moving part of the feed motor or a part driven by the feed motor and the distance moved by such moving part or (2) the velocity of a moving part of the transport motor or a part driven by the transport motor and the distance moved by such moving part.
Returning to decision block 62, where the media item has been acquired early, the minimum time to the next feed is increased at block 68 and the system continues to decision block 66. Where the media item has been acquired late as determined by decision block 64, the minimum time to the next feed is reduced at block 70 and the system continues to decision block 66. The determination at decision blocks 62 and 66 is in relation to an expected time. For example, the expected time represents the time it is expected that a media item will arrive at the detector 30 after the initiation of a feed cycle. The measured or calculated acquire time, a determined time for the specific media item, is compared to the expected time that the media item should have arrived at the detector 30 after initiation of the feed cycle.
It should be noted that the increase of minimum time to the next feed and the reduction of minimum time to the next feed, block 68 and block 70, are not necessarily of the same increment of time. The increase increment in feed time may be smaller than the decrease increment in feed time. This is to avoid the possibility of a jam. Thus, if the gap is too small, immediate action may be desirable to increase the gap to avoid a jam by significantly increasing the time to the initiation of feed of the next media item. If the gap is too large, gradual reductions in the gap size may be made to more gradually change the initiation of the next feed and increase the productivity of the system until the desired gap size is achieved. Where the acquire time is not too early and not too late, as determined by the decision blocks 62 and 64, there is no adjustment in the minimum time to the next feed. The adjustment in feed initiation timing between media items in that case is zero.
By keeping track of the acquire times, the feeding system 10 can be made to function more as intended with the desired high rate of speed of feeding media items, while avoiding undesired variations in media item gaps that could slow the process or create jams, which reduce the productivity of the system.
The system, when needed, increases or decreases the time before initiating the feed of a media item when the determined time differs from the expected time of the preceding media item. The adjustment (increases or decreases) or non-adjustment of the time is based on the immediately preceding media item feed cycle. That is, the time between initiating the feeding of the media item staged to be fed is controlled to be increased or decreased compared to the time lapse between the feed initiation of the immediately preceding media item and the media item before the immediately preceding media item. Thus, the feed initiation is controlled on the fly for every media item being fed seriatim from the stack of media items. When, however, the determined time is within the limits for the expected time, no timing adjustment change is made when controlling the time before initiating the feed of a media item in relation to the immediately preceding feed cycle. The limits for the expected time may vary for the particular system involved.
By controlling the time before initiating the feed of a media item in relation to the immediately preceding feed cycle, an adjustment can be made in initiating the feed of this media item only when needed and then in real time. Adjustment is only made in initiating the feed of a media item when the determined feed time of the media item of an immediately preceding feed cycle is detected as being out of limits, that is, the determined feed time of the media item of an immediately preceding feed cycle is detected as being early or late. When the determined feed time of a media item of an immediately preceding feed cycle is detected as being within the limits of the expected time, no adjustment is made in the initiation of the feeding of the media item to be next fed onto the transport. This enables the gap between media items being fed onto the transport to be maintained and adjusted, media item by media item. Thus, gap control between media items is maintained even as parts wear over time or other factors occur that impact feeding during a particular job run. This helps maintain the productivity of the feeding system by helping to reduce media item jams while maintaining the desired media item feed rate.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure and methodology described herein. Thus, it should be understood that the invention is not limited to the examples discussed in the specification. Rather, the present invention is intended to cover modifications and variations.
