Abstract:
A method and apparatus for charging toner for an imaging device includes an inactivity determining section that determines one or more periods of inactivity of the printing machine, a measuring section that measures a charge of the toner, and a charging section that charges the toner to a predetermined level based on at least one of the determined one or more periods of inactivity and the measured charge of the toner. The toner is charged to a predetermined level after recovery from the inactivity period so that the tribo-electric charge of the toner is enhanced for normal printing without causing unwanted effects when the imagining device recovers from inactivity.

Description:
BACKGROUND 
       [0001]    An imaging device, such as a xerographic machine, becomes inactive when not in use. When the imaging device becomes inactive for a long period of time, the device is often put into a “sleep mode” in which most of the electric power is cut off to save energy. When the imaging device “wakes up” from the sleep mode, the device starts warming up and performs imaging operations with toner. 
       SUMMARY 
       [0002]    The toner used in such an imaging device is charged with a tribo-electro-static charge (also known as tribo). A toner concentration (TC) sensor measures the concentration of the toner in the developer by detecting the tribo charge of the toner, and based on the output of the TC sensor, a toner dispenser may adjust the supply of toner to increase the concentration of the toner when the concentration of toner is low. 
         [0003]    If the imaging device is inactive for a long period of time, such as from the end of a business day to the next morning, the tribo charge of the toner may decrease. The tribo charge greatly affects the image quality in an imaging operation. Therefore, the image quality in an imaging operation after a delayed period may become inconsistent and darker than the image quality during normal or continual use. 
         [0004]    The exemplary embodiments address these and other issues. For example, in various exemplary embodiments, a method for charging a toner used in an imaging device may include determining one or more periods of inactivity of the imaging device, and charging the toner to a predetermined level based on the determined period of inactivity. 
         [0005]    In various exemplary embodiments, a method for charging toner used in an imaging device may include determining one or more periods of inactivity of the imaging device, measuring a toner charge level when the printing machine is recovered from the inactivity, and charging the toner to a predetermined level based on a difference between the measured charge of toner and a predetermined level. 
         [0006]    In various exemplary embodiments, an apparatus for charging a developer in an imaging device may include an inactivity determining section that determines one or more periods of inactivity of the imaging device, and a charging section that charges the toner to a predetermined level. 
         [0007]    In various exemplary embodiments, the above-described method and/or apparatus may be included in a xerographic machine. 
         [0008]    These and other features and advantages of the disclosed embodiments are described in, or are apparent from, the following detailed description of various exemplary embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Various exemplary embodiments of disclosed systems and methods will be described, in detail, with reference to the following figures, wherein: 
           [0010]      FIG. 1  is a diagram showing an imaging device according to an exemplary embodiment; 
           [0011]      FIG. 2  illustrates a toner and developer supply system according to an exemplary embodiment; 
           [0012]      FIG. 3  illustrates a block diagram showing a toner charging system that charges the toner according to an exemplary embodiment; 
           [0013]      FIG. 4  illustrates a flowchart showing a flow of charging the toner according to an exemplary embodiment; and 
           [0014]      FIG. 5  illustrates a flowchart showing another flow of charging the toner according to an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0015]    In various exemplary embodiments, the tribo charge of toner is returned to the level of normal operation after recovering from the inactivity. Using an intelligent method for controlling the tribo charge of toner, problems in the related art developer encounters are overcome or reduced. In various exemplary embodiments, the imaging device discussed herein includes, but is not limited to, a printer, copier, fax machine and any other printing device that may be suitable according to the exemplary embodiments. 
         [0016]    While the present disclosure will be described in connection with exemplary embodiments thereof, it will be understood that it is not intended to limit the disclosure to any one embodiment. 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 claims. 
         [0017]    A structure of an exemplary printing device is described. Here, a black and white printing machine is described as an example. However, as described later, it is appreciated that a universal developer may be used in a multicolor printing machine as well. 
         [0018]    As shown in  FIG. 1 , an exemplary printing machine  1  may include a photoreceptor belt  10 . The photoreceptor belt  10  may be supported by rollers  11 ,  12 ,  13 , and  14 . A motor  15  may operate the movement of the roller  14 , which in turn causes movement of the photoreceptor belt  10  in a direction, for example, indicated by an arrow  16 , for advancing the photoreceptor sequentially through the various xerographic stations. 
         [0019]    A portion of the photoreceptor belt  10  passes through a charging station A where a corona generating device  17  charges the photoconductive surface of the belt  10  to a relatively high, substantially uniform potential. The charged portion of the photoconductive surface is advanced through an imaging and an exposure station B. A document  18  may be positioned on a raster input scanner (RIS)  19 . One common type of RMS contains document illumination lamps, optics, a mechanical scanning drive, and a charged coupled device. The MIS captures the entire image from original document  18  and converts it to a series of raster scan lines. Alternatively, image signals may be supplied by an undepicted computer network. This information is transmitted as electrical signals to an image processing system (IPS)  20 . The IPS  20  converts image information into signals. 
         [0020]    The IPS  20  contains control electronics which prepare and manage the image data flow to a raster output scanning device (ROS)  21 , which creates the output copy image. When exposed at the exposure station B, the image areas are discharged to create an electrostatic latent image of the document. 
         [0021]    An exemplary developer station C, indicated generally by the reference numeral  100  (hereinafter referred to as a developer  100 ), advances development material into contact with the electrostatic latent image. The developer  100  may include a developer housing holding toner and a developer, i.e., carrier. The toner may be provided in a toner container  110 , and the developer may be provided in a developer container  111 . The toner container  110  and the developer container  111  may be installed on the developer station  100 . 
         [0022]    The complete developer in the developer container  111  may be added to the developer housing  100  prior to installing the toner container  110 . Once the developer has been added to the housing  100 , the empty developer container  110  may be removed. The toner container  110  may then be installed in the housing  100 . The toner dispensed from the toner container  110  and the developer dispensed from the developer container  111  are mixed in the developer housing  100 . 
         [0023]      FIG. 2  illustrates an exemplary structure of the developer housing  100 . As depicted therein, the developer housing  100  may include a developer roller  150 , a transport roller  152 , and a paddle wheel conveyor  154 . The developer roller  150 , transport roller  152 , and the paddle wheel conveyor  154  may be disposed in a chamber  156  of the developer housing  100 . As the toner and developer are dispensed from the toner container  110  and the developer container  111 , the mixture of the toner and developer may be dispensed over the paddle wheel conveyor  154  so as to be intermixed with the carrier granules contained therein, forming a fresh supply of developer material. 
         [0024]    The developer roller  150  includes a non-magnetic tubular member over a magnetic rotor and is rotated in the direction of arrow  162 . Similarly, the transport roller  152  may be made from a non-magnetic tubular member over a magnetic rotor and is rotated in the direction of arrow  164 . The exterior circumferential surface of the tubular member of the transport roller  152  may be roughened to facilitate developer material movement. 
         [0025]    The paddle wheel conveyor  154  may intermingle the fresh supply of toner particles with the carrier granules so as to form a new supply of developer material. The paddle wheel conveyor  154  may be made from a hub having a plurality of substantially equally spaced vanes extending radially outwardly therefrom and may be rotated in the direction of arrow  166 . In this way, the toner particles may be advanced to the transport roller  152 . With the rotation of the paddle wheel  154 , the transport roller  152  rotates and the developer roller  150  may move the developer material into a development zone  168 . In the development zone  168 , the toner particles may be attracted from the carrier granules to the electrostatic latent image recorded on a photoconductive surface  170  of a drum  117 . 
         [0026]    Referring again to  FIG. 1 , the developer housing  100  may include a toner concentration sensor (TC sensor)  121  to monitor the concentration of the mixed toner and developer by detecting the tribo charge of the toner. If the TC sensor  121  determines that the concentration of the toner in the developer, a signal may be sent to a controller  122 , which may be used to increase the supply of the toner so as to adjust the concentration of the mixture to a predetermined amount. The concentration may be predetermined and color or system dependent. 
         [0027]    The photoreceptor belt  10  may then advance the developed latent image to transfer station D. At the transfer station D, a medium  24 , such as, for example, paper, is advanced into contact with the developed latent images on the belt  10 . A corona generating device  22  may charge the medium  24  to the proper potential so that it becomes tacked to the photoreceptor belt  10  and the toner powder image is attracted from the photoreceptor belt  10  to the medium  24 . After transfer, a corona generator  23  charges the medium to an opposite polarity to detach the medium from the photoreceptor belt  10 , whereupon the medium is stripped from the photoreceptor belt  10 . 
         [0028]    Sheets of the medium  24  may be advanced to a transfer station D from a supply tray  25 . The medium  24  is fed from tray  25 , with sheet feeder  26 , and advanced to the transfer station D along a conveyor  27 . After transfer, the medium  24  continues to move in the direction of an arrow  28  to a fusing station E. The fusing station E may include a fuser assembly  29 , which permanently affixes the transfer toner powder images to the medium. Then the medium  24  is ejected to a tray  30  through a path  31 . 
         [0029]    Residual particles remaining on the photoreceptor belt  10  after each copy is made are removed at a cleaning station F for the next round of use. Accordingly, the image on the original is transferred to the medium  24  at a proper level of darkness. 
         [0030]    Next, how the tribo charge of toner is adjusted is discussed. 
         [0031]      FIG. 3  illustrates an exemplary embodiment of an intelligent toner charging system. The controller  122  may include inactivity determining section  500  which may determine an activity of the machine  1 . The inactivity may be an idle period of the machine  1  in which the machine  1  is not used by a user and may be determined by the status of a printing operation. That is, if the user does not activate the machine  1  and if the machine  1  falls into an idle state, then the inactivity determining section  500  may determine that the machine is inactive. 
         [0032]    The activity and inactivity of the machine  1  may be monitored by the inactivity determining section  500  periodically or continuously at any time. Such activity and inactivity of the machine  1  may also be monitored at a predetermined time of the day as may be configured by the user. 
         [0033]    The relationship between the inactivity time and the tribo charge of the toner may be approximated by the following power law: 
         [0000]      Tribo charge=Steady state of tribo charge×idle time C    
         [0034]    where C is a constant dependent on age of the toner and relative humidity (RH). An exemplary value of C is −0.02. 
         [0035]    The inactivity determining section  500  may include a user usage pattern determining section  510  that determines a usage pattern of the user. For example, the user usage pattern determining section  510  may monitor the usage of the user during the day and determine the usage pattern, such as the time for the first and last usages of the day and any inactivity pattern during the day that exceeds a predetermined length of time. The user usage pattern determining section  510  may be “self learning” and may determine the user pattern using an adaptive algorithm. Such an adaptive algorithm may detect long periods of inactivity, record the time and day of the week associated with these, and group/weight similar times to predict user behaviour. For example, the adaptive algorithm may record times of cycle-in (wake-up) after inactivity of more than 1 hour as follows: 8:10, 12:59, 8:06, 12:49, 8:09, 11:04, 12:55, 8:00, 13:05, 16:05, etc on weekdays. The adaptive algorithm may find two groups of highly weighed times and average them: 8:06 and 12:54. Two other time records (11:04, 16:05) may not be sufficiently associated with other time records to be considered a predictor of future behavior. 
         [0036]    The user pattern may be determined from a collection of information of such usage by the user for a predetermined length of time, such as one or two weeks. The collected information may be recorded in a later-discussed storing section  560 . The learning period may be continuous, a fixed initial time, or a moving window examining recent usage and may be pre-configured based on typical office hours followed by learning based on a moving window covering the past 4-8 weeks. The user may also configure the predetermined length of time in advance. Additionally, an initial usage pattern may be configured in advance. 
         [0037]    The inactivity determining section  500  may also include a predicting section  520  that predicts the next user usage from the determination made by the inactivity determining section  500 . In other words, the predicting section  520  predicts when the user is expected to next use the machine  1 , based on a user usage pattern. For example, the predicting section  520  may predict the time for the first usage of the day by the user, by taking an average of recorded times of daily first usage. 
         [0038]    Details of such calculations are described in, for example, U.S. patent application No. ______ (Attorney Docket No. 130732), which is incorporated herein by reference in its entirety. 
         [0039]    The inactivity determining section  500  may also include a measuring section  530  that measures the TC sensor  121 . The measuring system  530  may measure the sensor level at various times during the usage of the machine, including during the cycle-in and cycle-out of the machine. 
         [0040]    The calculating section  540  calculates a decay of the tribo charge of the toner based on the difference between any two sensor levels of the TC sensor  121 . For instance, the calculating section  540  may calculate the decay using the sensor level at the beginning of the inactivity period and the sensor level at the end of the inactivity level, that is, when the machine  1  “wakes up” from a sleep mode. The calculating section  540  may also calculate a decay of tribo charge based on an equation to predict the tribo when “waking” from sleep mode. 
         [0041]    The inactivity determining section  500  may further include an updating section  550  and a storing section  560 . The updating section  550  updates information on the user usage pattern, the predicated next user usage, sensor levels measured by the measuring section  530  and the decay calculated by the calculating section  540 . The storing section  560  may store such information for future usage. 
         [0042]    Upon determination of the inactivity, a charging section  570  may instruct the machine  1  to charge the toner to a predetermined level that is suitable for performing a printing operation. The charging section  570  may instruct the machine  1  to charge the developer based on the decay calculated by the calculating section  540 . 
         [0043]    A performing section  580  may perform a printing operation after the developer is changed by the charging section  570 . In particular, the performing section  580  pre-runs the machine  10  to perform the printing operation to ensure that the developer is at an adequate charge level for normal printing. 
         [0044]      FIG. 4  illustrates a flow chart of a method for charging the developer. The process starts at S 1000  and continues to S 1010 . As shown at S 1010 , a determination may be made as to whether the machine  1  is inactive. The inactivity may be, for example, an idle period of the machine  1  in which the machine  1  is not used by a user and may be determined by the status of printing operation. 
         [0045]    If the machine  1  is not inactive, then the process repeats at S 1010 . Otherwise, the process makes a prediction of the next cycle as shown at S 1020 . For example, at step S 1020 , a determination may be made as to whether the user&#39;s predicted next usage has been reached. If the predicted user&#39;s next usage has not been reached, the process continues as shown at S 1030 . If the predicted user&#39;s next usage has been reached, the process continues as shown at S 1070 . 
         [0046]    More specifically, a determination may be made as to whether the machine  1  has awaken from a sleep mode, that is, whether the machine  1  is in operation, as shown at S 1030 . If so, the process continues as shown at S 1040 . If not, the process returns to the prediction cycle as shown at S 1020 . 
         [0047]    Furthermore, as shown at S 1040 , the idle time may be calculated, and then the user pattern may be determined from the idle time, as shown at S 1050 . That is, when the machine  1  became inactive and when the machine  1  was operated next, may be determined. The next user usage may be determined based on this user pattern and the previous user patterns. The user pattern may be determined using an adaptive algorithm. 
         [0048]    Then the user pattern and predicted next cycle may be stored in a storing section for future use, as shown at S 1060 . Then the process ends as shown at S 1100 . 
         [0049]    If the determination of the predicted next cycle, as shown at S 1020  is positive, that is, if the predicted next user&#39;s usage has been reached, then decay may be calculated from the inactivity period, as shown at S 1070 . For example, the tribo charge=steady state of tribo charge×idle time C , where C may be a constant dependent on age of the toner and RH. 
         [0050]    Then, the toner may be charged based on the calculated decay, and the machine  1  may pre-run the developer, as shown at S 1080 . The tribo charge of the toner may be measured, and a determination may be made as to whether the toner is charged to a predetermined level, as shown at S 1090 . If so, the process ends at S 1100 . If not, the process may return and repeat to charge the toner, as shown at S 1080 . 
         [0051]      FIG. 5  illustrates a flowchart of a second method for charging the developer. The process starts at S 2000  and continues to S 2010 . More specifically, the process begins when a determination is made as to whether the machine is inactive, as shown at S 2010 . The inactivity may be an idle period of the machine  1  in which the machine  1  is not used by a user and may be determined by the status of printing operation. If the machine  1  is not inactive, then the process as shown at S 2010  may repeat. 
         [0052]    If the machine  1  is inactive, then a sensor level of the TC sensor  121  may be measured and recorded, as shown at S 2020 . Then, a determination may be made as to whether the machine  1  has become active, as shown at S 2030 . If the machine  1  has not become active, then the process repeats, as shown at S 2030 . If the machine  1  has become active, then the sensor level of the TC sensor  121  may again measure and record, as shown at S 2040 . 
         [0053]    Next, a difference between the two sensor levels may be calculated to determine decay of the toner, as shown at S 2050 . That is, the change in the tribo charge levels may be determined. A determination may be made as to whether the difference between the two sensor levels is greater than a first value k 1 , as shown at S 2060 . The first value k 1  may be a threshold value to determine that the tribo charge of the toner is low enough to cause deficiency in the printed image. 
         [0054]    If the difference between the two sensor levels is not greater than the first value k 1 , the process may continue and perform normal marking operations, as shown at S 2070 . Then, the process may end as shown at S 2080 . 
         [0055]    If the difference is greater than the constant k 1  at S 2060 , the process may move to S 2090 . That is, the toner may be charged by a multiplication of a second value k 2  and the difference between the sensor levels, as shown at S 2090 . The value k 2  may be a constant to adjust the tribo charge of the toner to the predetermined charge level. Then, the process may continue to step S 2100  and may perform a marking operation. 
         [0056]    The toner optionally may again be charged by a multiplication of a third value k 3  and the difference between the sensor levels, as shown at S 2110 . This ensures that the toner has a tribo charge for the normal operation. Then, the process may end as shown at S 2080 . 
         [0057]    Either one of the above-described exemplary methods may be sufficient to adjust the tribo charge of the toner. However, it will be appreciated that both methods may be used as a combination to even more accurately adjust the tribo charge of the toner. 
         [0058]    The disclosed methods may be readily implemented in software, such as by using object or object-oriented software development environments that provide portable source code that can be used on a variety of computer or workstation hardware platforms. Alternatively, appropriate portions of the disclosed intelligent toner charging system may be implemented partially or fully in hardware using standard logic circuits or a VLSI design. Whether software or hardware is used is dependent on the speed and/or efficiency requirements of the system, the particular function, and the particular software or hardware systems or microprocessor or microcomputer systems being utilized. The processing systems and methods described above, however, can be readily implemented in hardware or software using any known or later developed systems or structures, devices and/or software by those skilled in the applicable art without undue experimentation from the functional description provided herein together with a general knowledge of the computer arts. 
         [0059]    It will be appreciated that variations of the above-disclosed and other features and functions, or alternatives thereof may be desirably combined into many other different systems or applications. Also, various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art, and are also intended to be encompassed by the following claims.