Abstract:
Toner transfer in an imaging device having a developer roller ( 5 ) that applies toner to a photoconductive roller  7  is determined by counting pels ( 38 ) and by counting operating cycles ( 56 ). Additionally in the embodiment, various device factors including darkness setting and type of toner are also applied to the totals. An adjustment factor, stored in a toner cartridge memory, is originally substantially one and may be adjusted based on subsequent knowledge or observations of the results. A page count of pages imaged is also used dependently as a second basis for amount of toner transferred.

Description:
TECHNICAL FIELD 
     This invention relates to determining toner usage in an imaging device having a photoconductive roller that receives toner from a developer roller. 
     BACKGROUND OF THE INVENTION 
     Automatic determination of toner usage is useful both to signal an operator when the hopper or other source of toner is empty or approaching empty, and, similarly, to signal the operator when a chamber of toner cleaned from the photoconductor is full or approaching full. 
     Measurement of toner used by counting pels is well known. (Pels are dots or other small picture elements.) This invention employs counting pels as a major element of it determination of usage. However, employing only pel counting does not account for start and end of imaging device operation nor for blank or near blank pages made by the imaging device. 
     Typically, at start up several cycles of rotation of the photoconductor occur and, although ideally no toner would be used, this invention recognizes that, in total, a nontrivial amount of toner is used with such blank operations. Also, when an image has very light pet usage, this invention recognizes that, in total, a significant amount of toner is used in printing such near blank or blank pages. 
     Additionally, a number of operating factors of the imaging device may be used to scale the results from pet applications and blank operations. 
     DISCLOSURE OF THE INVENTION 
     This invention is directed to imaging devices, which are controlled by electronic data processing and to imaging based on pels (small picture elements). Such digital imaging devices are now widely available as printers and copiers and the like. 
     In this invention the number of pels imaged is determined and that number is multiplied by at least one pel weight factor. Similarly the amount of photoconductor rotation during non-imaging operation is determined and that amount is multiplied by at least one rotation weight factor. 
     In specific implementations the weight factors may vary over usage as the amount of toner usage varies with different darkness settings of the imaging device, different process speeds, different resolutions for printing, different papers or other media being imaged, and different ambient conditions, and with exceptionally high coverage imaging and with the amount of previous toner used from an unreplenished source. Accordingly the weight factors reflecting these are better applied with each page printed or revolution of the photoconductive roller. 
     Additionally, a factor of essentially  1 , which may be termed an adjustment factor, is initially applied, and that factor may be changed for future operations, based on actual experience. The adjustment factor can be stored in memory on a replaceable toner cartridge, from which it is obtained by the printer on which the cartridge is installed. 
     The exact weight factors and how many different factors are employed depend on the specific characteristics of the imaging device and are obtained by actual tests on representative imaging devices. Accordingly, exact values for a specific device are incidental to this invention. 
     The factors may vary moderately when the ultimate result is for determination of the amount of toner in the cleaner chamber rather than for the amount of toner used from the toner supply. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The details of this invention will be described in connection with the accompanying drawings, in which 
     FIG. 1 is illustrative of the primary imaging apparatus to which this invention relates, and 
     FIGS. 2A,  2 B, and  2 C (collectively FIG. 2) are illustrative of a specific implementation of this invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a perspective view with top elements removed for clarity of apparatus used in laser imaging. The toner supply is hopper  1  (toner not shown for clarity). During imaging operations paddle  3  moves toner from hopper  1  to developer roller  5 . Developer roller  5  rotates with photoconductor roller  7  (often termed a photoconductor drum). After imaging, toner remaining on the photoconductor roller  7  is scraped into cleaner chamber  9  by a cleaning blade (not shown) or other cleaning mechanism. The elements shown in FIG. 1 constitute a conventional, replaceable toner cartridge, which, when no longer usable, is extracted from the imaging device and replaced by a fresh and usable cartridge. 
     As the foregoing and related elements and operation is entirely conventional, other parts supporting the imaging operation will not be discussed in detail. Among these elements are a laser and optical system to form a latent electrostatic image on photoconductor  7  and at least one electronic data processing apparatus and associated electronic memory to control imaging of the imaging device. 
     When the imaging device is activated several parts must be brought to operating speed and temperature. Included in these parts are the developer roller  5  and the photoconductor roller  7 , as well as typically a mirror rotated by a motor in the optical system and toner paddle  3 . Accordingly, at activation several rotations of rollers  5  and  7  typically occur without imaging. At the end of activation, typically at least one rotation of roller  5  and  7  occurs so as to clean residual toner from photoconductor roller  7 . 
     Since the entire imaging operation is controlled by an electronic data processor, the unique details of imaging are defined by the code being executed and determination of pels printed and revolutions without imaging, operating speed, and exceptionally high coverage are readily available as a routine matter of adding branch instructions and the like to the program of the electronic data processor. 
     Information about the media, darkness settings, and resolution typically will be entered by the operators or communicated in data of the print job. Toner type information, as well as an adjustment factor unique to this invention, are contained in memory of the toner cartridge and retried electronically by the data processing system of the printer. Environmental conditions, including the combined effects of humidity and temperature, can be obtained in a known manner by an automatic observation by the electronic data processor of voltage between the photoconductor roller  7  and a transfer roller (not shown) in nip contact with the photoconductor roller  7  used in imaging to attract toner from the photoconductor roller  7  to paper or the like in the nip. The voltage on the transfer roller is increased until a predetermined current is obtained. The final level of that voltage defines the environment. 
     Also, in accordance with this invention, an adjustment factor is employed not related to individual information for each factor, which define the other factors. This adjustment factor permits subsequent versions of the imaging device to be modified based on actual experience during use. Accordingly, if actual measurements of toner usage are found to be slightly too high, the adjustment factor in subsequent imaging would be changed, for example, from 1 to 0.95. Similarly, if actual measurements are found to be slightly too low, the adjustment factor in subsequent imaging would be changed, for example, from 1 to 1.05 
     A specific implementation is illustrated in FIG.  2 . Operation is initiated by action  20  at power on reset (POR) or cover closed (CC). The prior usage sum is then observed from nonvolatile memory in action  22 . The prior usage sum is the usage amounts adjusted by adjustment factors computed as follows. 
     Decision  24  compares the usage total (from action  65 ) to a predetermined number indicative of end of life (for example, cleaner full). Decision  24  also compares the count of pages imaged (action  38 ) with a predetermined number indicative of end of life. If either is yes, a warning is sent to the operator in action  26  and decision  28  takes no further operation occurs until the operator enters an acknowledgement that the reset action has been taken (i.e., toner has been added or the cleaner chamber has been emptied or replaced). When the acknowledgement occurs, decision  28  is yes and action  30  resets the nonvolatile memory count to zero or the equivalent. 
     When decision  24  was no, decision  32  compares the usage total (from action  65 ) to a predetermined number indicative of near end of life. Decision  32  also compares the count of pages (action  38 ) with a predetermined number indicative of near end of life. If either is yes, action  34  initiates a warning to the operator while continued imaging is permitted. 
     Decision  36  is involved, both when decision  32  is no and when action  34  is invoked by decision  32  being yes. Decision  36  determines if a page is being printed. If no, decision  36  continues to observe at regular intervals whether a page is being imaged (this normally would be known from the software condition that a bit map for the page is being composed by the electronic data processor controlling the imaging). When decision  36  is yes, action  38  increments a page count to one more. (A page count can be a confirming calculation to determine toner usage. The page counting of the embodiment is of all pages moved through the printing operation, as the number of such pages which are blank or nearly blank is normally insignificant to being indicative of toner usage.) 
     Action  40  then counts the number of pels imaged for the page. (In the imaging device, which images by parts of pels, such as 4 vertical slices in a 1200-dots-per-inch pel, where any such slice in a pel is to be imaged, the entire pel may be considered imaged.) The number of pels imaged is then adjusted by a factor for the amount of toner used from the toner source. (More toner is used per pel as toner is depleted from an original source.) Action  42  defines the amount of toner used from the current total for toner usage and compares that with a number for total amount in the toner source. That is then used in action  44  to provide a factor for current toner usage for each pel. This factor is applied to the number of pels in multiplier  46  and the resulting number is stored in action  48 . 
     The amount in action  48  is then adjusted by other factors as discussed in the foregoing. These are multiplied to the amount in action  48  in multiplier  50  and the amount resulting is stored in action  52 . (With respect to each page the factors may be multiplied together and the resulting number multiplied with the previous amount in multiplier  50 .) 
     The total in action  52  is the final calculation for pels. It is summed in adder  53  with a second amount developed from cycle operations, determined from decision  54 . Decision  54  determines if an operating cycle of the photoconductor roller  7  is occurring. If no, decision  54  continues to observe at regular intervals whether a cycle is occurring (This could be known from any number of actions of the software, such as motor operation rotating roller  7 .). When decision  54  is yes, action  56  increments a cycle count by one more. 
     This number is then adjusted by a factor for the amount of toner used from the toner source. Action  58  defines the amount of toner used from the current total for toner usage and compares that with a number for total amount in the toner source. That is then applied in action  60  to provide a toner usage amount. 
     The value in action is then adjusted by other factors as discussed in the foregoing. These are multiplied to the amount in action  60  in multiplier  62  and stored in action  64 . 
     The total in action  64  is the final calculation for cycles. It is summed in action  53  with the amount for pels in action  52 . That total is stored in action  65  and represents toner usage as discussed in the foregoing (i.e. when compared against predetermined amounts in decisions  24  and  32 , toner usage is ascertained). The amount stored in action  65  is stored in memory in action  66  for subsequent use by decision  24  and  32 . 
     In this embodiment, only process speed, environment and toner type are acted on as factors for cycles of operation. Factors such as darkness setting, resolution and media type are pertinent to pel printing, but not to operation in which no pels are printed. Should the imaging device react to, for example, high darkness setting during low or no pel printing, a factor for that might be added for application to the cycle amount. 
     In an ideal calculation the amount from pel printing would be subtracted from the amount for the cycle for which the pels are printed. In fact, however, most printing is at low coverage so that such a calculation would not be significant to the result. Where coverage is high, a factor for that is employed and that factor, obtained by trial and error, necessarily compensated for the amount added for each high coverage cycle. 
     In this embodiment, the change in toner usage per pel with usage from the toner source is toward higher usage as toner is depleted (believed to be because fines initially print in greater amount). This change is scaled linearly in the embodiment of FIG. 2, which provides satisfactory accuracy. 
     The page count of pages is kept, as indicated in the discussion of FIG.  2 . This can serve as an alternative measurement of toner usage in that the warning and shut down discussed with respect to actions  26  and  34  would also be initialed at a predetermined page count. 
     The adjustment factor is used as conditions change or are better understood. It changes for future printers. For example, when toner measurement has been running high, the adjustment factor may be changed accordingly, for example from 0.95 to 0.90. A major advantage of the adjustment factor is that it can be stored in a periodically is replaceable member, specifically the toner cartridge, and thereby permit adjustments of the imaging operation without physically recalling the printer or other imager. 
     As many factors have potential influence in the scaling and some may be minor, it is anticipated that implementations of this invention can take a wide variety of forms. The machine factors generally have values between 0.85 and 1.2, but darkness setting, resolution and toner type might be much greater (for example, darkness setting at 0.65 to 1.1, resolution at 025 to 1, and toner type at 1 to 2).