Abstract:
According to aspects described herein, there is disclosed an apparatus and method for controlling a position of a belt in a printing system. The apparatus including a roller assembly for engaging at least a portion of the belt. The roller assembly extending laterally across the belt. The apparatus including a pair of laterally spaced support arms each rotatably supporting opposed ends of the roller assembly. Each support arm being pivotally coupled to the printing system for movement about a pivot axis extending substantially in the lateral direction. The apparatus also including a pair of actuating assemblies each configured to pivot a different one of the support arms about the pivot axis. The pivotal movement of each of the pair of support arms by the respective actuating assemblies being independent of the other.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority and is a continuation of U.S. patent application Ser. No. 12/415,321 filed on Mar. 31, 2009, the disclosure of which is incorporated herein in its entirety by reference. 
     
    
     TECHNICAL FIELD  
       [0002]    The presently disclosed technologies are directed to controlling and/or adjusting the lateral position of an image handling belt in a printing system. In particular, it is directed to an apparatus and method for belt steering and control. 
       BACKGROUND  
       [0003]    In general, conventional image forming apparatus such as copiers and laser printers employing an electrophotographic system or electrostatic recording system as described above have a configuration in which image exposure is performed on a surface of a photosensitive drum to form an electrostatic latent image; the electrostatic latent image formed on the surface of he photosensitive drum is developed by a developing device to form a toner image in a predetermined color, and the toner image is directly transferred on to and fixed on recording paper or temporarily transferred to an intermediate transfer body and is thereafter transferred on to the recording paper at a time to form an image. 
         [0004]    An example of a conventional image forming apparatus is shown in U.S. Pat. No. 6,349,192 to Yoshino et al. In such apparatus, when a color image is formed by an image forming apparatus  500 , as shown in  FIG. 5  herein, a configuration may be employed in which a latent image forming step of performing image exposure on a surface of a single photosensitive drum  300  with an image exposure device  301  to form an electrostatic latent image associated with a predetermined color and a developing step of developing the latent image with a developing device for the associated color are repeated for a predetermined number of colors; toner images having the predetermined colors sequentially formed on the surface of the photosensitive drum are subjected to primary transfer onto an intermediate transfer belt on a multiplex basis; and the toner images are subjected to secondary transfer from the intermediate transfer belt on to a substrate media at a time to form a color image. 
         [0005]    Image forming apparatus include so-called tandem type image forming apparatus having plural (e.g., four) photosensitive drums each associated with a predetermined color and having a configuration in which toner images in predetermined colors sequentially formed on surfaces of the respective photosensitive drums are subjected to primary transfer on to an intermediate transfer belt  2  on a multiplex basis; and the toner images are thereafter subjected to secondary transfer from the intermediate transfer belt on to a substrate media  7  at a time to form a color image. For example,  FIG. 5  shows a tandem type image forming apparatus having four image forming units  300 , i.e., individual forming units for colors such as black (K), yellow (Y), magenta (M) and cyan (C). The four image forming units  300  are horizontally arranged at constant intervals from each other. Below the image forming units for the colors, an intermediate transfer belt  2  for transferring toner images sequentially formed by the respective image forming units in an overlapping relationship with each other is provided such that it is driven by plural rolls  200 - 203  including driving rolls for rotation in the direction indicated by the arrow. For example, the intermediate transfer belt  2  is configured in the form of an endless belt by forming a synthetic resin film made of polyimide or the like having flexibility in the form of a belt and by connecting both ends of the synthetic resin film formed in a belt-like configuration by means of welding or the like. 
         [0006]    In printing systems, transfer belts are also used to handle and/or transfer substrate media as well as the images for transfer to the substrate media. Thus, an image can be transferred after being deposited on a substrate media. As with the intermediate transfer belts described above, such substrate media transfer belts  3  move along a travel path in a process direction and are supported by various rollers or support shoes intended to maintain the belts in position. However, sometimes due to heavy usage, poor belt conicity or hardware misalignments the belts can slide or shift laterally on the rollers that drive them. Such lateral movement can lead to belt walk-off, where the belt comes off the rollers, which can in-turn lead to operating delays as well as possible damage to the belt, substrate media or the system itself. 
         [0007]    In certain printing systems that use transfer belts, edge guides are used to limit lateral movement. However due to extensive usage and the fragile nature of the belts, edge guides can compromise the integrity of the belt as well. Alternatively, belt edge detectors are employed to track lateral belt movement and potentially shut-down the system before the belt walks off a roller. While belt edge detectors are helpful in preventing damage to the belt or the system, they do not automatically correct the improper belt position. Also, the manual adjustment or re-adjustment of a belt or the belt roller pitch can be time consuming and negatively effect production deadlines. 
         [0008]    Accordingly, it would be desirable to provide an apparatus or method of controlling and/or adjusting the lateral position of one or more belts in a printing system in order to avoid processing interruptions or delays, damage to the system or substrate media and other shortcomings of the prior art. 
       SUMMARY  
       [0009]    According to aspects described herein, there is disclosed an apparatus and method for controlling a position of a belt in a printing system. The apparatus including a roller assembly for engaging at least a portion of the belt. The roller assembly extending laterally across the belt. The apparatus including a pair of laterally spaced support arms each rotatably supporting opposed ends of the roller assembly. Each support arm being pivotally coupled to the printing system for movement about a pivot axis extending substantially in the lateral direction. The apparatus also including a pair of actuating assemblies each configured to pivot a different one of the support arms about the pivot axis. The pivotal movement of each of the pair of support arms by the respective actuating assemblies being independent of the other. 
         [0010]    According to other aspects described herein, at least one of the support arms can be configured to not pivot while the other of the support arms is pivoted by one of the actuating assemblies. Also, the actuating assemblies can be configured to pivot both support arms in opposite directions about the pivot axis. Additionally, the actuating assemblies can be configured to pivot both support arms in the same direction about the pivot axis. The pivotal movement of each of the pair of support arms about the pivot axis is relative to the other of the support arms. The pair of actuating assemblies can each include a cam in engagement with a respective one of the support arms. The cams can each engage a rotatable bearing member removeably secured to a respective one of the support arms. The support arms can each include at least one mounting slot for receiving a fastener to secure each support arm to the printing system, the mounting slot passing through the support arm. 
         [0011]    According to other aspects described herein, there is disclosed an apparatus for controlling a position of a transfer belt in a printing system. The apparatus including a transfer belt, a roller assembly, a pair of laterally spaced apart support arms, a pair of rotating cams and a pair of motor assemblies. The transfer belt for handling one or more images and/or a substrate media in a printing system. The transfer belt being generally moveable in a process flow direction within the printing system, wherein a lateral direction extends substantially along the belt and substantially perpendicular to the process flow direction. The roller assembly for engaging at least a portion of the belt. The roller assembly extending laterally across the belt. The pair of laterally spaced support arms each supporting opposed ends of the roller assembly. Each support arm being pivotally supported allowing pivotal movement about a pivot axis extending substantially in the lateral direction. The pair of rotating cams each engaged with a portion of a different one of the support arms for pivotally moving the respective support arms. Rotation of one of the cams pivoting the respective support arm to which it is engaged. The pair of motor assemblies each drivingly coupled to a different one of the pair of rotating cams. The motor assemblies selectively rotating the cams independently of one another. 
         [0012]    According to other aspects described herein the transfer belt can handle an image applied directly thereon for subsequent transfer to a substrate media. Also, at least one of the support arms can be configured to not pivot while the other of the support arms is pivoted by one of the cams. Also, the cams driven by the motor assemblies can be configured to pivot both support arms in opposite directions about the pivot axis. Additionally, the cams driven by the motor assemblies can be configured to pivot both support arms in the same direction about the pivot axis. Further, the pivotal movement of each of the pair of support arms about the pivot axis can be relative to the other of the support arms. The cams can each engage a rotatable bearing member removeably secured to a respective one of the support arms. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0013]      FIG. 1  is an inboard side top perspective view of a belt position control apparatus, showing a cut-away portion of a transfer belt, in accordance with an aspect of the disclosed technologies. 
           [0014]      FIG. 2  is an outboard top perspective view of the belt position control apparatus of  FIG. 1 , with the transfer belt removed. 
           [0015]      FIG. 3  is an outboard side perspective view of a cut-away portion of a printing system including an image transfer module with the transfer belt removed, including the apparatus for controlling belt position of  FIG. 2 . 
           [0016]      FIG. 4  is an inboard top perspective view of an alternative belt position control apparatus in accordance with an aspect of the disclosed technologies. 
           [0017]      FIG. 5  is a schematic side elevation view of a prior art image forming apparatus. 
       
    
    
     DETAILED DESCRIPTION  
       [0018]    Describing now in further detail these exemplary embodiments with reference to the Figures. A transfer belt position control apparatus and method is preferably used in a select location or locations of an image and/or substrate media path or paths of various conventional printing assemblies. Thus, a portion of an exemplary printing system image intermediate transfer belt path is illustrated herein, in particular a modular portion including an image handling assembly. 
         [0019]    As used herein, a “printer” or “printing system” refers to one or more devices used to generate “printouts” or a print outputting function, which refers to the reproduction of information on “substrate media” for any purpose. A “printer” or “printing system” as used herein encompasses any apparatus or portion thereof, such as a digital and/or analog copier, bookmaking machine, facsimile machine, multi-function machine, etc. which performs a print outputting function. 
         [0020]    A printing system can use an “electrostatographic process” to generate printouts, which refers to forming and using electrostatic charged patterns to record and reproduce information, a “xerographic process”, which refers to the use of a resinous powder, such as toner, on an electrically charged plate, roller or belt and reproduce information, or other suitable processes for generating printouts, such as an ink jet process, a liquid ink process, a solid ink process, and the like. Also, such a printing system can print and/or handle either monochrome or color image data. 
         [0021]    As used herein, “substrate media” refers to, for example, paper, transparencies, parchment, film, fabric, plastic, or other substrates on which information can be reproduced, preferably in the form of a sheet or web. 
         [0022]    As used herein, “image transfer belt”, “media transfer belt”, “transfer belt” or “belt” refer to, for example, an elongated flexible web supported for movement along a process flow direction. For example, an image transfer belt is capable of conveying an image in the form of toner for transfer to a substrate media. Another example includes a media transfer belt, which preferably engages and/or carries a substrate media within a printing system. Such belts can be endless belts, looping around on themselves within the printing system in order to continuously operate. Accordingly, belts move in a process flow path around a loop in which they circulate. A belt will engage a substrate media and/or carry an image thereon over at least a portion of the loop. Image transfer belts for carrying an image or portions thereof can include non-stretchable electrostatic or photoreceptor belts capable of accumulating toner thereon. 
         [0023]    As used herein, “roller” or “steering roller” refer to a rotatably supported generally cylindrical member for directly engaging a belt. A “roller assembly” includes a roller or steering roller as well as additional support structure that allow the rollers to operate as desired. Rollers include rotating cylinders, as well as driven elements, journalled on bearings and a shaft. 
         [0024]    As used herein, “sensor” refers to a device that responds to a physical stimulus and transmits a resulting impulse for the measurement and/or operation of controls. Such sensors include those that use pressure, light, motion, heat, sound and magnetism. Also, each of such sensors as refers to herein can include one or more point sensors and/or array sensors for detecting and/or measuring characteristics of a belt, image or substrate media, such as speed, orientation, process or cross-process position. Thus, reference herein to a “sensor” can include more than one sensor. 
         [0025]    As used herein, “actuating assembly” refers to any mechanism and/or control system used to move elements in or around the system. In particular, a control system driving a motor, gears, a cam shaft and/or cams for engaging and moving other elements are part of an actuating assembly. 
         [0026]    As used herein, the terms “process,” “process direction” and “process flow direction” refer to a process of printing or reproducing information on substrate media. The process direction or process flow direction is a flow path in which a belt moves as part of the system in order to convey an image and/or a substrate media from one location to another within the printing system. A “cross-process direction” is generally lateral to the process direction. 
         [0027]      FIGS. 1 and 2  show inboard and outboard perspective views, respectively, of a belt position control apparatus  10  in accordance with an aspect of the disclosed technologies. The embodiments illustrated herein are particularly suited for a printing system that uses an intermediate image transfer belt for receiving and transporting the developed image. Preferably, an image is formed by collecting toner or other resinous powder into electrostatic charged patterns and transferred to an electrostatically charged belt that holds the powder in the pattern. Generally, the image is transferred to the image transfer belt from an electrostatically charged drum. The image transfer belt then transports the image to a subsequent transfer station/area were the image is transferred to a substrate media. Thereafter, the substrate media holding the transferred image can be further transported for fusing the image to the substrate media or further processing of the image and/or the substrate media. It should be understood that a belt position control apparatus  10  in accordance with the disclosed technologies herein can also be used for a media transfer belt that directly conveys substrate media. 
         [0028]    As shown in  FIG. 1 , in operation a belt  2  moves generally in a process direction P, supported by and engaged with a number of rollers, such as steering roller  20 . The steering roller  20  is part of a roller assembly of the belt position control apparatus  10 . The rollers, and particularly steering roller  20 , are preferably cylindrical or at least generally cylindrical and rotatably supported at opposed ends by support elements. The rollers generally extend laterally to the process direction and are adapted to rotate in the process direction. Opposed inboard and outboard edges of the belt  2  are generally disposed at or substantially near opposed ends of the rollers. For example, the belt  2  is preferably 10-12 mm smaller than the rollers to maintain a 5-6 mm spacing between the lateral edges of the belt  2  and the ends of the rollers. 
         [0029]    A pair of support arms  30  are laterally spaced at opposed ends of the steering roller  20 . A roller support end  39  of each support arm  30  acts as a yoke to rotatably support the steering roller  20 . From the roller support end  39 , the support arms  30  extend away from the steering roller  20 , preferably toward an actuating assembly  50 . The actuating assembly  50  can be disposed at the opposed end  31  of each support arm  30 . Each of the support arms  30  is pivotally coupled to the printing system in which it is used by a post and bearing assembly  21 . Thus, a line connecting the two opposed post and bearing assemblies  21  defines a pivot axis  25  for the belt position control apparatus  10 . Additionally, the belt position control apparatus  10  is preferably secured to the printing system by additional stand-off fasteners. Each fastener secures to the printing system through oversized slots  26   a,    27   a,    28   a,    26   b,    27   b,    28   b  in the support arms  30 . The slots  26   a,    27   a,    28   a,    26   b,    27   b,    28   b  allow for limited pivotal movement of the support arms  30  relative to the stand-off fasteners, while also providing stability to the apparatus  10 . For ease of assembly, some of the slots, such as slots  26   a,    26   b,  can have an open end. It should be understood that fewer or greater stand-off fasteners with corresponding fewer or greater slots could be provided. Alternatively, the bearing assemblies  21  could be designed to provide enough support to minimize or eliminate the need for stand-off fasteners and slots. 
         [0030]    Preferably, at the opposite end of the support arms  30 , from the steering roller  20 , is the actuating assembly  50 . The actuating assembly preferably includes a pair of cams  40   a,    40   b  that engage the ends  31  of support arms  30 . Preferably, the support arm ends  31  are each provided with a bearing washer  41 , which is rotatably supported on a fixed post laterally projecting from the support arm ends  31 . The cams  40   a,    40   b  each engage one of the bearing washers  41  to actuate the support arm ends  31 . Also, the cams  40   a,    40   b  are both secured to a cam shaft  42 . The cam shaft  42  is preferably rotationally supported for selective bi-directional rotation and includes a fixedly secured cam gear  45 . Rotation of the cam shaft  42  will rotate both cams  40   a,    40   b,  which in-turn will actuate the support arm ends  31  via the bearing washers  41 . Preferably, the outboard cam  40   a  has the same rise/degree as the inboard cam  40   b,  but the profile with respect to how the cams  40   a,    40   b  each engage the bearing washers  41  is opposite. Thus, as the cam shaft  42  and cams  40   a,    40   b  rotate, each support arm end  31  will pivot in an opposite direction. In this way for example, when the cam shaft  42  rotates such that the support arm end  31  on the outboard side pivots in a clockwise direction (0.02 mm/degree), the support arm end on the inboard side preferably pivots in a counter-clockwise direction the same amount, and vise-versa. The size of the bearing washer  41  can also be changed to provide a greater or lesser degree of pivot of the support arms  30 . Alternatively, the rise, degree, size or shape of the cams  40   a,    40   b  could be changed not only to change the degree of pivot angle, but also to change the pitch of the cam profile. It should be understood that the particular profile of the pair of cams  40   a,    40   b  can be designed to suit the particular rate at which the support arms  30  and the steering roller  20  should tilt. Additionally, the support arms  30  can be biased against the cams  40   a,    40   b  via springs  37  or other biasing mechanisms. As yet a further alternative, the actuating assembly  50  could employ a direct gear linkage to activate the pivotal movement of the support arms  30 . 
         [0031]    As the support arms  30  are made to pivot by the actuating assembly  50 , so too roller support ends  39  are made to pivot opposite from one another. Preferably, the support arms  30  are made to pivot in an equal but opposite direction. Thus, the axis of the steering roller  20  will tilt relative to the overall belt position control apparatus  10 . For example, in a neutral position the axis of the steering roller  20  could be parallel to the pivot axis  25 , but after the actuating assembly tilts the steering roller  20  they would no longer be parallel. Thus, the steering roller  20  is made to pivot about a virtual axis perpendicular to its own longitudinal axis. 
         [0032]    The actuating assembly  50  is preferably run by a control system (not shown) that activates the drive motor  51 . Preferably, the bi-directional drive motor  51  includes a motor gear  52  that engages cam gear  45 . It should be understood that while gears  52 ,  45  are illustrated as smooth wheels, that they are preferably formed as toothed gears. Alternatively, the gears  52 ,  45  could be replaced with a wheel and belt/chain configuration. Regardless, activation of the drive motor  51  rotates the gears  52 ,  45 , cam shaft  42 , both cams  40   a,    40   b  and the intervening members in order to pivot the steering roller  20 . In order to maintain calibration and control of the drive motor  51 , elements such as a home position flag  55  or sensor  57  can be provided. 
         [0033]    Additionally, other elements such as a tensioning member  60  can be incorporated into the belt position steering control apparatus of the presently disclosed technologies. For example, rotation of tensioning member  60  can be made to retract steering roller  20  toward the pivot axis  25 . Such a mechanism can be provided to adjust or more easily install a flexible but non-stretchable belt  2 . Also, the tensioning member  60  can be coupled to the opposite side of the apparatus through tensioning axle  62 , in order to control the steering roller  20  symmetrically. It should be understood that preferably the tensioning axle  62  is sized to loosely pass through both support arms  30 . In this way, the tensioning axle  62  does not limit or retard the relative pivotal movement that should occur between the support arms  30 . 
         [0034]      FIG. 3  shows the belt position control apparatus  10  installed in a part of a printing system  5 . In particular, this embodiment shows an image intermediate transfer belt module with the transfer belt removed. Although not visible in this figure, the internal post and bearing assemblies  21  provide a pivot axis  25  for the support arms  30 . The fasteners and slots  26   a,    27   a,    28   a  are visible, with the fasteners fixedly secured to the printing system  5 . It should be understood that the slots  26   a,    27   a,    28   a  (as well as opposed slots  26   b,    27   b,    28   b ) should be large enough to allow the proper range of pivoting for the support arms  30 . 
         [0035]      FIG. 4  shows an alternative embodiment of the disclosed technologies, where the opposed cams  40   a,    40   b  of the control apparatus  10   a  are actuated by separate motor and gear assemblies  50   a,    50   b.  In this embodiment, two cam shafts are provided to couple the separate inboard and outboard sides, allowing them to be controlled and actuated independently. 
         [0036]    Preferably in all the above embodiments, during operation one or more belt edge sensors  15  can measure at least the lateral position of the belt  2  with respect to the rollers. Once the belt  2  is measured to have drifted/walked beyond a threshold point toward either edge of the rollers, the actuating assembly  50  will be activated to tilt the steering roller  20  in the appropriate direction in order to compensate. Thus, the drive motor  51  would cause the cam shaft  42  to turn in one direction in order to pivot the steering roller  20  clockwise or the cam shaft  42  would be turned in the opposite direction in order to make it pivot counter-clockwise. Once the belt edge sensor(s)  15  detect the appropriate correction in the lateral position of the belt  2 , the drive motor  51  could be reversed to bring the steering roller  20  back to a neutral position. 
         [0037]    Preferably, the belt edge sensor(s)  15  communicate electronically with a controller that steers the belt in accordance with the disclosed technologies. The controller is designed to maintain a designated lateral position of the belt  2  by maintaining a threshold condition associated with the elements steering the belt  2 . For example, the threshold condition could be a predetermined output voltage from the belt edge sensor(s)  15 . Thus, preferably a belt edge sensor output voltage of approximately 2.4 volts is maintained. If an increase or decrease in the output voltage is detected, the controller sends a signal to the drive motor(s)  50 ,  50   a,    50   b  to rotate in the proper direction in order for the belt edge sensor(s)  15  to achieve the desired voltage output (i.e., 2.4 volts). Alternatively, a certain tolerance or variation from the threshold condition could be tolerated without activating the steering system. Additionally, a fail-safe can be provided such that if, for any reason, the voltage should stray too far from the desired output, the system or at least a portion thereof will shut down. Thus, for example if the voltage were to reach one or more fail-safe values, such as an increase to 4.3 volts or decreases to 0.5 volts, the controller could shut down the system and declare a lateral belt position error. The fail-safe value(s) being predetermined based on design parameters of the printing system and/or the roller assembly. This could protect the belt  2  from getting damaged. Additionally, the controller could hold or store parameters of a position associated with the drive motor, the configuration of the actuating assembly and/or the roller assembly tilt. Such information could be held or stored, for example when the power is shut down from a machine power down (for example at the end of a work day or an impending machine service action). In this way, when the machine power resumes, the controller will return the drive motor to the stored position. For example, this could be achieved using the drive motor flag  55  and home sensor  57 . This action would in turn position the steering support arms  30  back to where they were before the power was shut down. 
         [0038]    Often printing systems include more than one printing module or station. Accordingly, more than one belt position control apparatus  10 ,  10   a  can be included in an overall printing system. 
         [0039]    It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.