Abstract:
A method and system to sense an amount of material such as toner in a container held in a horizontal position within a machine, such as a printing machine. A level sensor senses an amount of material within a dispensing unit which causes the level sensor to issue a signal. The dispensing unit is external to the container. The container holding the material is rotated, and a rotation direction reversed to a direction normally used to dispense the material. The reverse rotation direction moves the material to a closed end of the container. The container is then moved in a forward direction following the rotation of the container in the reverse direction. The forward rotation moves the material to the open end of the container, and the material further moves into the dispensing unit. A signal is generated when a sufficient amount of material has been moved into the dispensing unit. A time period is determined which represents the time it took to move the material from the closed end of the material, until the signal indicating a sufficient amount of material exists in the dispensing unit. The amount of material in the container is estimated by use of the determined time period.

Description:
BACKGROUND 
       [0001]    The present application relates to electrophotographic printing. More specifically, the application relates to a system and method for calculating an amount of toner in a toner container located within a electrophotographic printing machine. 
         [0002]    In the well-known process of electrophotographic printing, a charge retentive surface, typically known as a photoreceptor, is electrostatically charged, and then exposed to a light pattern of an original image to selectively discharge the surface in accordance therewith. The resulting pattern of charged and discharged areas on the photoreceptor form an electrostatic charge pattern, known as a latent image, conforming to the original image. The latent image is developed by contacting it with a finely divided electrostatically attractable toner which is held on the image areas by the electrostatic charge on the photoreceptor surface. Thus, a toner image is produced in conformity with a light image of the original being reproduced. The toner image may then be transferred to a substrate or support member (e.g., paper), and the image affixed thereto to form a permanent record of the image to be reproduced. 
         [0003]    The electrophotographic process is useful for light lens copying from an original as well as printing electronically generated or stored originals such as with a raster output scanner (ROS), where a charged surface may be image wise discharged in a variety of ways. 
         [0004]    Existing electrophotographic printing machines are commonly supplied with replaceable containers which hold the toner. Typically, such a container is positioned horizontally within the printing machine, and therefore gravity does not ensure movement of the toner towards the latent image. Thus a mechanism, such as an auger, is needed to move the toner. One particular container design is a cylindrical container having an opening near one end and internal spiral ribs, which when rotated urges the toner to the opening. Such containers are also called bottles or cartridges among other names. 
       BRIEF DESCRIPTION 
       [0005]    A method and system to sense an amount of material such as toner in a container held in a horizontal position within a machine, such as a printing machine. A level sensor senses an amount of material within a dispensing unit which causes the level sensor to issue a signal. The dispensing unit is external to the container. The container holding the material is rotated, and a rotation direction reversed to a direction normally used to dispense the material. The reverse rotation direction moves the material to a closed end of the container. The container is then moved in a forward direction following the rotation of the container in the reverse direction. The forward rotation moves the material to the open end of the container, and the material further moves into the dispensing unit. A signal is generated when a sufficient amount of material has been moved into the dispensing unit. A time period is determined which represents the time it took to move the material from the closed end of the material, until the signal indicating a sufficient amount of material exists in the dispensing unit. The amount of material in the container is estimated by use of the determined time period. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a schematic elevation view of an illustrative electrophotographic printing machine in which the concepts of the present application may be incorporated; 
           [0007]      FIG. 2  is an exploded perspective view of a toner cartridge; 
           [0008]      FIG. 3  depicts dispensing of toner from the container; 
           [0009]      FIGS. 4A-4C  illustrate the operation of the toner level sensing system of the present application; and 
           [0010]      FIG. 5  is a plan view showing a development apparatus which may be used in the printing machine of  FIG. 1 , including the toner level sensing system of  FIGS. 4A-4C . 
       
    
    
     DETAILED DESCRIPTION 
       [0011]      FIG. 1  depicts an electrophotographic printing machine to which concepts of the present application are incorporated. The printing machine includes a photoreceptor  10  in the form of a belt having a photoconductive surface layer  12  on a grounded electroconductive substrate  14 . The belt is driven by motor  16  along a path defined by rollers  18 ,  20  and  22 , the direction of movement being counter-clockwise as viewed and as shown by arrow  24 . Initially a portion of belt  10  passes through a charge station A at which a corona generator  26  charges surface  12  to a relatively high, substantially uniform, potential. A high voltage power supply  28  is coupled to generator  26 . 
         [0012]    Next, the charged portion of photoconductive surface  12  is advanced through exposure station B. At exposure station B, an original document  30  is positioned on a raster input scanner (RIS)  32 . The RIS captures the entire original document and converts it to a series of raster scan lines and (for color printing) measures a set of primary color densities. This information is transmitted to an image processing system (IPS)  34 , which is the control electronics used to prepare and manage the image data flow to raster output scanner (ROS)  36 . A user interface (UI)  38 , is in communication with the IPS. The UI enables the operator to control the various operator adjustable functions. The output signal from the UI is transmitted to IPS  34 . The signal corresponding to the desired image is transmitted from IPS  34  to ROS  36 , which creates the output copy image. ROS  36  lays out the image in a series of horizontal scan lines with each line having a specified number of pixels per inch. 
         [0013]    After the electrostatic latent image has been recorded on photoconductive surface  12 , belt  10  advances the latent image to development station C. At development station C, a development system  38 , develops the latent image recorded on the photoconductive surface. The chamber in toner housing  40  stores a supply of toner  42  in a toner container  44  held in place by supports  46 . Also shown is a sump housing  48 . The toner may be a two component toner of at least magnetic carrier granules having toner particles adhering triboelectrically thereto. It should be appreciated that the toner may likewise comprise a one component toner consisting primarily of toner particles. 
         [0014]    After the electrostatic latent image has been developed, belt  10  advances the developed image to transfer station D, at which a copy sheet  50  is advanced by roll  51  and guides  52  into contact with the developed image on belt  10 . A corona generator  53  is used to spray ions onto the back of the sheet so as to attract the toner image from belt  10  the sheet. As the belt turns around roller  18 , the sheet is stripped, with the toner image thereon. 
         [0015]    After transfer, the sheet is advanced by a conveyor (not shown) to fusing station E. Fusing station E includes a heated fuser roller  54  and a back-up roller  55 . The sheet passes between fuser roller  54  and back-up roller  55  with the toner powder image contacting fuser roller  54 . In this way, the toner powder image is permanently affixed to the sheet. After fusing, the sheet advances through chute  56  to catch tray  57  for subsequent removal from the printing machine by the operator. 
         [0016]    After the sheet is separated from photoconductive surface  12  of belt  10 , the residual toner particles adhering to photoconductive surface  12  are removed at cleaning station F by a rotatably mounted fibrous brush  58  in contact with photoconductive surface  12 . Subsequent to cleaning, a discharge lamp (not shown) floods photoconductive surface  12  with light to dissipate any residual electrostatic charge. 
         [0017]    It is believed that the foregoing description is sufficient for purposes of the present application to illustrate the general operation of an electro-photographic printing machine which is capable of incorporating the concepts of the present application. 
         [0018]    Turning to  FIG. 2 , illustrated is a more detailed view of container  44 , used to store the supply of toner  42 . Container  44  has a generally cylindrical shape and an opening  47  located on a first end  49 . In this embodiment container  44  includes a first generally cylindrically shaped portion  60  having an open end  61  proximate the opening  47  and closed end  62  opposite open end  61 . To urge toner  42  from first generally cylindrical shaped portion  60  container  44  includes spiral rib  63  located on an interior periphery  64  of cylindrically shaped portion  60 . The spiral rib  63  may have either a right hand or a left hand orientation depending on the corresponding rotation of container  44 . 
         [0019]    Container  44  also includes a ring shaped portion  65  which extends from open end  61 . The ring shaped portion  65  includes radial protrusions  66  which extend inwardly from interior periphery  67 . 
         [0020]    The radial protrusions  66  have a carrying face  68  which curves in the direction of rotation  69  of container  44  as the radial protrusions  66  extend toward centerline  70  of container  44 . The radial protrusions  66  thereby form pockets  74  along carrying face  68 . Pockets  74  become filled with toner  42  from open end  61  and carry toner  42  along inner periphery  67 . 
         [0021]    Container  44  further includes a plate shaped end portion  76  which extends from a second face  78  of ring shaped portion  65 . Plate shaped portion  76  includes first end  49  as well as opening  47 . Plate shaped portion  76  also includes an interior hub  80  which extends inwardly from a disc area  82  of end portion  76 . A puncturable seal  84  is located within interior hub  80 . Seal  84  serves to contain toner  42  during installation and removal of container  44 . To provide sealing in addition to puncturable seal  84  when container  42  is installed into the machine, a secondary seal  86  is located in interior hub  80  spaced outwardly from and parallel to puncturable seal  84 . The secondary seal  86  contains a central opening  88  which slidably fits over an auger tube  114  (see  FIG. 5 ) and seals upon installation into development system  38  (see  FIG. 5 ). The plate shaped end portion  76  further includes pins  90  extending outwardly from outer face  92  of the disc area  82 . The pins  90  are used to interconnect with development system  38 . 
         [0022]    Turning to  FIG. 3 , provided is a simplified illustration of the operations used to dispense toner from container  44 . The system of  FIG. 3  includes toner level sensing capabilities to determine if sufficient toner is available. During normal operation, container  44  rotates in direction  69 , causing toner  42  to migrate to the opening of the container and out into toner dispensing unit  94 , and then to toner housing  40  of  FIG. 1 . As depicted by this figure, ring-shaped portion  65  is motivated by drive mechanism/gearing arrangement  96 , which is connected to motor  98 . Particularly, gearing arrangement  96  rotates container  80  in direction  69  by actuation of motor  98 . This movement causes interior ribs  63  to push toner  42  to the opening of container  44  where it is then moved into dispensing unit  94 , such as by an auger system. 
         [0023]    Included in this figure is a toner level sensor  100  connected, via a signal line  102 , to an input of controller  104 . Level sensor  100  senses the amount of toner in dispensing unit  94 , and depending on the amount of toner in dispensing unit  94  it issues a signal to controller  104  informing controller  104  as to the status of toner in dispensing unit  94 . An output of controller  104  is in operative communication with motor  98 , and controls operation of motor  98 . For example, when sensor  100  indicates a depleted toner level, in normal operation motor  98  is energized, causing the container to rotate in direction  69 , whereby internal rib  63  migrates the toner to the open end of the container and into the dispensing unit  94 . Once sensor  100  senses sufficient toner and supplies this signal to controller  104 , the controller signals motor  98  to stop, thereby stopping rotation of container  44 . By this design, toner is delivered to the system to ensure a continuous supply during imaging operations. However, while this system is effective for supplying toner when there is sufficient toner in the container, it does not address the issue of determining when the container is low or nearly empty and will need to be replaced with another container which is full of toner. 
         [0024]    Turning now to  FIGS. 4A-4C , illustrated are toner level sensing concepts of the present application to address the above issue. More particularly,  FIG. 4A  depicts a situation where toner  42  in dispensing unit  94  is below level sensor  100 , a signal informing the controller of this situation is therefore provided to controller  104  via signal line  102 . At this point during normal operation, controller  104  would issue a signal instructing motor  98  to rotate container  44  in direction  69  so to migrate toner to the opening of the container in order to refill toner dispensing unit  94 . However, in this present embodiment, gearing system  96  and motor  98  are arranged in such a way that container  44  can be rotated in a reverse direction  69 ′. Then controller  104  issues a signal to motor  98  to operate in the reverse direction. The instructions causing the reverse rotation may be software instructions within controller  104 . 
         [0025]    As illustrated in  FIG. 4A , reversing rotation of container  44  causes internal rib  63  to migrate toner  42  away from the opening, to the back closed end of container  44 . Once the reverse rotation has moved the toner to the back of the container, this reverse rotation is stopped. Then as illustrated in  FIG. 4B  normal rotation is resumed. At the start of normal rotation (the 69 direction), controller  104  will also start a software timer/clock (Clock), which continues until level sensor  100  sends a signal to controller  104  that it has been replenished, such as shown, for example, in  FIG. 4C . The length of time the container is rotated in the reverse direction can be a predetermined set amount of time, where the set time is determined by experimentation. However, alternatives such as use of a sensor associated with the container or other parts of the printing machine could also be used. 
         [0026]    When the toner reaches the open end of the container, the toner is picked up by an auger system for dispensing the toner into the dispenser unit  94 , as in the normal operation. The time period it takes the innermost toner (e.g.,  106  of  FIGS. 4A ,  4 B) to traverse the length of the container and replenish the dispensing unit to alter the state of the level sensor will vary according to the position of the toner. This time will relate directly to the quantity of toner in the cartridge. In other words, the fuller the cartridge, the closer the leading edge of the toner (pushed back to the closed back end) will be to the dispensing auger, and thus the less distance to travel along the continuous pitch auger (see  112   FIG. 5 ). 
         [0027]    The signal generated by level sensor  100  may be considered a trigger signal which initiates the level sensing operation. 
         [0028]    The triggering of the level sensor  100  may occur due to operation of an algorithm/software program stored within a memory area of controller  104 . Where, when the program is run within a computation area (e.g., CPU) of the controller, the controller a lows the toner within the dispensing unit to drop below the trigger threshold. For example, the program may simply stop motor  98  from continuing the normal rotation of the container when the toner level sensor has signaled for additional toner, and rather initiates the process described in connection with  FIGS. 4A-4C . 
         [0029]    The amount of time from the start of the forward rotation until the toner sensor is again replenished is used to determine the amount of toner remaining in container  44 . In one embodiment, the elapsed time is recorded in the controller and is used in a transfer function derived from normal engineering calculations to determine the amount of remaining toner. Parameters which may be considered in the development of the transfer function include the size of the container, speed of rotation, density of the toner, among others. 
         [0030]    An alternative procedure to determine the amount of toner within a container is to obtain empirical data through repetitive testing. Where the results of the tests are correlated the amount of toner within the container. Particularly, a table can be generated by redundant testing wherein, for example, the container is filled with a known amount of toner. Then the system is operated in accordance with the concepts of  FIGS. 4A-4C  to determine the migration time of the toner. Next, known amounts of toner are removed from the container and additional tests are undertaken to determine the toner migration time for these toner amounts. The results are collected into a table which associates toner amounts with time values. The table may be electronically stored within the controller, or may be recorded at some separate location. 
         [0031]    Results of both above embodiments alone or in combination can then be used by the printing device to issue low toner alerts to a user. Such alerts may be generated via existing audio or visual components which are part of the printing machine. In some embodiments controller  104  includes an electronic display which issues a low toner alert which would be visible to a user and/or a speaker system which issues an audible alert. 
         [0032]    In one embodiment, the steps shown in  FIGS. 4A-4C  are undertaken by controller  104  at known idle times of the printing machine, for example, immediately prior to going to a power-save mode. Alternatively, the tests could be undertaken during a moderately low area coverage print run, if required, as buffer capacity of toner exists in the developing unit which would allow sufficient time to run the procedure without a productivity impact. Replenishing the toner prior to this procedure could be a method of forcing the toner level in the dispensing unit to drop below the sensing threshold. 
         [0033]    In one embodiment, the motor drive  98  and gearing/transmission system  96  may use a one-way clutch in the gear train connecting the toner container and the pick-up auger drive (see  FIG. 5 ) to prevent the pick-up auger drive from reversing while the toner cartridge is reversing 
         [0034]    Referring now to  FIG. 5 , shown is a more detailed embodiment of development system  38  in which container  44  is installed in a horizontal position. 
         [0035]    Development system  38  includes toner housing  40  from which the bottle supports  46  extend. A sump housing  48  extends upwardly from one end of the toner housing  40 . A toner dispensing unit (or feed mechanism)  94  extends through sump housing  48  and outwardly therefrom in the direction of centerline  110 . The feed mechanism  94  extends through opening  47  of container  44 , centerline  110  being co-linear with centerline  70 . Feed mechanism  94  is in the form of auger  112  located within tube  114 . The tube  114  preferably has an inlet opening  116  in the upper portion of the tube  114  near a first end  118  of tube  114 . The tube  114  also has an outlet opening  120  in the bottom portion of tube  114  near second end  122  of tube  114 . The development system  38  further includes container drive motor  98  which may be located anywhere within development system  38 . The container drive motor  98  serves to rotate container  44  as well as auger  112 . It should be appreciated, however, that a separate motor for auger  112  and a separate motor for the marking particle container  44  may be used. Any suitable gear train of gearing arrangement  96  which allows for reverse rotation of container  44 , while inhibiting reverse rotation of the auger  112  may be used. For example, motor  98  may have a pinion gear  124  extending inwardly therefrom. A sun gear  126  slidably rotates about tube  114  and meshes with pinion gear  124 . 
         [0036]    To urge sun gear  126  against container  44  and assure the mating of pins  90  with stops  128 , preferably, the development system  38  further includes a spring  130  slidably fitted about tube  114  between the sump housing  48  and second face  132  of sun gear  126 . To interconnect container  44  to feed mechanism  94 , stops  128  are located on face  132  of sun gear  126  and are aligned adjacent pins  90  of container  44  to cooperate therewith. 
         [0037]    To assure container  44  is adequately axially positioned relative to feed mechanism  94 , a stop  134  located preferably on toner housing  40  secures container  44  by restraining closed end  62  of container  44 . A series of gears  134  preferably interconnect drive motor  98  to the auger  112 . The gears  134  are so configured that when motor  98  rotates in the direction of arrow  136 , auger  112  will be rotated in a direction to urge the toner  42  from the inlet opening  116  to the outlet opening  120 . When motor  98  rotates in the direction of arrow  136 ′, causing reverse rotation of container  44  (i.e., the operation shown in  FIG. 4A ) auger  112  is prevented from a reverse drive. 
         [0038]    The development system  38  further preferably includes a toner auger  138  extending from bottom of the sump housing  48 . The auger  138  extends outwardly along the length of toner housing  40 . The auger  138  is located within conduit  140 . The conduit  140  includes one or more dump holes  142  which permit toner  42  to enter the toner housing  40 . Auger  130  can be driven by a toner auger motor  144  to independently control the flow of toner  42  from sump housing  48  to the toner housing  40 . 
         [0039]    Particles of toner  42  fall into inlet opening  116  of the tube  114  and are thereby carried away by the auger  112 . 
         [0040]    Particles received at inlet opening  116  translate along auger  112  in the direction of arrow  146  toward outlet opening  120 . The toner particles exit the tube  114  at outlet opening  120  and fall to the bottom  140  of the sump housing  48 . Auger  138  then carries the marking particles along conduit  140  and through dump holes  142  to the toner housing  40  where they are used in the developing process. 
         [0041]    While the foregoing has been described in conjunction with various embodiments, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. For example, while the foregoing discussion has focused on toner material other materials may also take advantage of the described concepts. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims. 
         [0042]    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. Also that 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.