Patent Application
20130221602
1. Field of the Disclosure
The present disclosure relates to a printing apparatus that includes a friction retard feeder, and more particularly, to an improved jam clearance system for use in such feeders.
2. Description of Related Art
When a sheet is jammed in a downstream location in the paper path of a printer it is more than likely that a sheet will be left partially fed in the feed nip of the input media feeder of virgin sheets into the printer. Presently, this sheet is manually cleared by the user, but it is very likely that it will be damaged during this process and possibly leading to an unclearable jam, and therefore, to an unscheduled maintenance call. Also, when there is a multiple sheet jam in the feed head of the media feeder itself due to, for example, a misfeed the user must manually clear the jam, however, some parts of the sheets may be in a location that is unclearable which could lead to an unscheduled maintenance call to a repairman.
Heretofore, various jam clearing methods have been employed. For example, U.S. Patent Publication No. 20080079210 A1 shows a marking machine that includes a system that automatically clears itself of jams in the machine when the machine is unattended. The paper transport is enabled to move forward and backward and when a jam occurs it will automatically move backward until the jam is cleared. In U.S. Pat. No. 4,231,567 a method and apparatus for clearing jams in the transport path of a copier includes the steps of sensing a jam, clustering in process sheets at the jam or at a location upstream of the jam location, while simultaneously allowing the sheet downstream of the jam location to continue. In U.S. Pat. No. 6,010,127 a buckle chamber is provided along a sheet path where jammed sheets are compiled during a down cycle during a jam.
Unfortunately, even though the jam clearance techniques of the above prior art are useful, the jam clearance problems of virgin sheet input feeders mentioned-hereinabove are still present.
In answer thereto, provided hereinafter is a fully active retard feeder that feeds sheets from a stack and adapted in response to a jam in feed head of the retard feeder or downstream jam to move a partially feed sheet in a reverse direction back into the stack.
The disclosed system may be operated by and controlled by appropriate operation of conventional control systems. It is well known and preferable to program and execute imaging, printing, paper handling, and other control functions and logic with software instructions for conventional or general purpose microprocessors, as taught by numerous prior patents and commercial products. Such programming or software may, of course, vary depending on the particular functions, software type, and microprocessor or other computer system utilized, but will be available to, or readily programmable without undue experimentation from, functional descriptions, such as, those provided herein, and/or prior knowledge of functions which are conventional, together with general knowledge in the software of computer arts. Alternatively, any disclosed control system or method may be implemented partially or fully in hardware, using standard logic circuits or single chip VLSI designs.
The term ‘sheet’ herein refers to any flimsy physical sheet or paper, plastic, media, or other useable physical substrate for printing images thereon, whether precut or initially web fed.
As to specific components of the subject apparatus or methods, it will be appreciated that, as normally the case, some such components are known per se’ in other apparatus or applications, which may be additionally or alternatively used herein, including those from art cited herein. The cited references, and their references, are incorporated by reference herein where appropriate for teachings of additional or alternative details, features, and/or technical background. What is well known to those skilled in the art need not be described herein.
Various of the above-mentioned and further features and advantages will be apparent to those skilled in the art from the specific apparatus and its operation or methods described in the example(s) below, and the claims. Thus, they will be better understood from this description of these specific embodiment(s), including the drawing figures (which are approximately to scale) wherein:
While the disclosure will be described hereinafter in connection with a preferred embodiment thereof, it will be understood that limiting the disclosure to that embodiment is not intended. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the disclosure as defined by the appended claims.
The disclosure will now be described by reference to preferred fully active retard feed system embodiments that include an apparatus for returning sheets to a feed tray in response to a jam.
For a general understanding of the features of the disclosure, reference is made to the drawings. In the drawings, like reference numerals have been used throughout to identify identical elements.
In the following description, the term sheet “media”, “sheet”, “print media”, or “sheet media” is used herein to refer to physical sheets of paper, plastic, cardboard, or other suitable physical substrates that can be employed for printing, whether precut or initially web fed and subsequently cut.
A media transport system in an image-forming device employs one or more sets of rollers for reliably driving a sheet along a media transport path. The present disclosure describes a roll system including a preferably non-liftable nudger roll positioned above a stack of sheets, however, if desired, the nudger roll could be moveable between positions in contact with the top sheet and raised out of such contact. A feed roll and a retard roll are mutually loaded to form a feed nip, positioned at the start of a media transport path. A drive motor powers the nudger roll and the feed roll in a feed direction (rotating to propel media sheets downstream on the media transport path). The drive motor is coupled to the nudger roll and feed roll through a feed clutch. The retard roll includes a slip clutch, driven in a reverse direction (opposite the feed direction), having a breakaway torque chosen below the torque imposed by a media sheet being fed through the feed nip. In the normal operation, the drive motor, operating through the feed clutch, drives the feed roll and the nudger roll in a feed direction, and the nudger roll picks the top sheet off the stack and propels it into the feed nip. The sheet imposes sufficient torque on the retard roll to cause the retard roll to slip on the slip clutch to rotate in the feed direction. Thus, the forward rotation of the retard roll, feed roll, and the nudger roll drives the sheet in a forward direction.
If a jam occurs elsewhere along the media transport path, all rolls are stopped, and that action often leaves a sheet partially fed through the feed nip. To deal with that situation, the system disengages the feed clutch. The drive motor continues to run and rotate the retard roll in a reverse direction. Here, no torque is imposed on the retard roll, as the feed roll is stationary, and therefore the slip clutch drives the retard roll in a reverse direction, driving the media sheet back onto the stack.
Retard roll 114 is carried on a slip clutch 118, which in turn is carried on retard roll shaft 116. The drive motor drives slip clutch in a reverse direction, opposite the feed direction, and both the retard clutch and retard roll rotate on retard roll shaft 116. The slip clutch 118 engages the retard roll 114 to drive it in the reverse direction, but at a predetermined breakaway torque, the slip clutch disengages, allowing the retard roll to turn freely. The predetermined breakaway torque is chosen to be below the toque imposed on the retard roll by a media sheet but above a value explained below.
When the media transport system 100 operates in normal feeding state, as noted above, the drive motor 115, being powered and coupled to the feed roll shaft 106, rotates the feed roll shaft 106 with the rotation speed of the drive motor. The feed clutch 108, being engaged to the feed roll shaft 106 and the feed roll 104, moves the sheet along the media transport path 134. On such engagements, the feed roll shaft 106 transfers the driving torque to the feed roll 104, thus rotating the feed roll 104 in the feed direction. The rotating feed roll 104 thus propels the sheet through the feed nip 105 along the media transport path 134.
When the media transport system 100 detects a jam at some point downstream from the feed nip 105, the imaging device's control system senses a jam condition and stops nudger roll 124 and feed roll 104 by disengaging feed clutch 108. That situation often leaves a single sheet 103 partially fed through the feed nip 105. The drive motor continues to operate, however, and the control system does not disengage slip clutch 118. In this situation, feed roll 104 freewheels, imposing no work on retard roll 114. Thus, the slip clutch 118 drives retard roll 114 in a reverse direction, returning sheet 103 to the top of the stack 102. This same procedure is followed if there is a jam in the feed nip 105. Also, if there is a misfeed or a jam in the feed head, any partially feed sheet caught in the feed nip 105 is reversed back into tray 132.
This reversal of functionalities enables the media transport system 100 to resets itself through the described clear jam state and return the image-forming device to a normal functional state without any human intervention.
The fault recovery process 300 shown in the flow charts of
Alternatively, if tray 4 is feeding, any internal fault is monitored at block 350. If there is a fault it is determined in block 352. If the determination is that the lead edge of the first sheet feed from tray 4 is late as shown in block 356, feed motor 115 is turned ON for 1000 ms. If the feed sensor in block 362 goes clear, the feed motor is stopped and the clutch is disengaged and the process ended at block 370. However, if the fault determination in block 352 is that the lead edge of the sheet being fed is late to the HCF exit sensor as shown in block 354, the HCF transport motor is actuated to run the take away rolls for 1000 ms as indicated in block 358 and ended in block 370.
As shown in block 364, the events taking place in blocks 326 and 360 will turn the feed motor ON. The clutch is not engaged so only the retard roll is running which will move the sheet back into the tray.
In recapitulation, a process and apparatus is disclosed for running a fully active friction retard feeder with the drive roll clutch disengaged for a period of time after a jam occurs to drive any sheets stopped in the feed nip back into the tray. This will prevent those sheets from being torn if the tray is pulled out as part of the jam clearance process. As a result, the incidence of torn media during jam clearance is reduced, customer satisfaction is improved and occasional unscheduled maintenance is prevented due to pieces of media being left in awkward places.
The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others. Unless specifically recited in a claim, steps or components of claims should not be implied or imported from the specification or any other claims as to any particular order, number, position, size, shape, angle, color, or material.
