This invention relates to ink cartridges for ink-jet printers, and more particularly, to a new and useful method and system for predicting the usage of ink to determine whether a print job may be completed using currently installed ink cartridges.
Ink-jet printers typically use one or more ink cartridges to print black and/or color images. In-line printers used for printing on mailpieces oftentimes employ multiple ink cartridges for printing the various “zones” on a mailpiece (or package) including zones for the return address, mailing address, and barcode symbology. Generally, it is these ink cartridges that account for a large portion, if not the largest portion, of the overall life cycle costs associated with the operation of such printers. In fact, the cost of a single set of ink-cartridges can approach the cost of the original printer (which typically has installed an initial set of cartridges).
In view of these operating expenses, it is important to know when these ink cartridges will be depleted, particularly when one ink cartridge may be “Ink Out” before several others when performing the same print job. For example, there is a high probability that an ink cartridge dedicated to printing the barcode symbology will, due to the relatively large ink requirements associated therewith, run out of ink before a neighboring ink cartridge dedicated to printing, for example, a line of the return address. If an operator is unaware that one of the ink cartridges is out, then hundreds of mailpieces may be missing a necessary print element before the misprint is noticed. As such, the mail run may require reprint resulting in lost operator time, wasted ink and/or a multiplicity of reject mailpieces.
Currently, printers and/or systems monitoring a print job will display the current ink level available within a cartridge. That is, an operator is provided with information regarding the percentage of ink remaining as compared to a full ink cartridge. When the display reveals a low ink level, the operator must either (i) carefully monitor the ink level as it approaches an ink out condition or (ii) remove and replace the ink cartridge prematurely (which may still contain five to ten percent) with a full cartridge. Inasmuch as option (ii) is more often selected for convenience, valuable ink is often discarded to negate the expense or embarrassment of operator error.
Other printers and/or systems display predictive data to a user/operator in connection with the number of pages which may be printed based upon the remaining volume of ink in a cartridge. That is, a printer may display the number of pages which may be printed based upon the current ink level of the ink cartridge. While such displays provide an estimate of potential print capacity, the estimate is based simply upon the ink consumption of a typical printed page. If, for example, a user/operator is printing a series of photographs (which consumes a far greater amount of ink than a typical printed page), the displayed estimate cannot be relied upon to accurately measure or determine the sufficiency of ink to print the series of photographs. That is, since the average ink consumption may be based upon the usage associated with printing a letter-sized sheet having thirty (30) lines of printed subject matter per page, a photograph consumes a far greater volume of ink and no longer is representative of the ink consumption average used to predict future print capacity. It will, therefore, be appreciated that the current predictive techniques do not rely upon the unique characteristics of a particular print job, but simply upon a predetermined, historical average of ink consumption of an average user producing a typical sheet of printed material.
A need, therefore, exists for a method and system for accurately predicting the usage of ink to determine whether a print job may be completed.
The accompanying drawings illustrate presently preferred embodiments of the invention and, together with the general description given above and the detailed description given below serve to explain the principles of the invention. As shown throughout the drawings, like reference numerals designate like or corresponding parts.
A method and system is provided for predicting ink usage during a print job for an ink jet printer and displaying information in connection with ink usage on a system monitor. The method steps include determining the initial ink level of an ink cartridge and developing a histogram of ink usage associated with a threshold number of items to be printed. The threshold number is less than the total number of items to be printed and should be an amount representative of each of the print items. The usage associated with the threshold number, i.e., the histogram, may then be extrapolated to evaluate the number of items which can be printed before the ink cartridge is depleted. The number of items which can be printed is then displayed to the user/operator on a system monitor so that a determination can be made concerning whether the print job may be completed. Additionally, the time remaining and/or the ink cartridge to be depleted first can be displayed to provide additional information to the operator concerning the replacement/replenishment of ink cartridges.
The present invention is described in the context of an in-line printer for printing various zones on the face of a mailpiece, though the invention is applicable to any ink-jet printer wherein knowledge of an ink out condition is desirable.
Ink cartridges have a predetermined quantity of ink therein, which may be measured in various volumetric terms. For example, an HP45A ink cartridge, manufactured by Hewlett Packard, located in Palo Alto, Calif., contains about forty-two milliliters (42 mL) of ink. Irrespective the volumetric measurement, whether in liters, ounces etc., all can be converted to a number of ink drops wherein each drop corresponds to a predetermined quantity of ink delivered with each pulse or bubble of ink projected from the ink jet nozzles. A typical pulse or droplet of ink produces a small bubble or sphere which is about 50-60 microns in diameter or about 50-60×10−6 meters. The volume of the ink sphere in cubic meters (m3) is given by the relationship (1.0) below:
V(cubic meters)=4/3(π)(d/2)3 (1.0)
wherein d is the diameter of the ink sphere. According to equation 1.0, the volume of a typical ink droplet is about 1.13×10−13 m3.
Inasmuch as a typical ink cartridge contains about 0.042 liters of ink, the total number of ink droplets is given by equations (2.0 and 3.0) below:
1 m3 (1.13×10−13)=1000 liters (1.13×10−13)=1.13×10−10 liters (2.0)
X=0.042 liters/(1.13×1010−10 liters)=3.72×108 (3.0)
wherein X is the number of ink droplets which can be delivered from a forty-two (42) milliliter ink cartridge.
Surprisingly, the measurement in terms of ink drops within each cartridge is highly accurate and can be relied upon with about a one percent (±1%) error factor. Consequently, since the number of ink drops (also analogous to the pixels of an image) required to print a character e.g., the letter “T” in Times New Roman font at a 12 point size is known, then the cumulative number of ink drops associated with an entire page or document can also be determined. This determination may be derived empirically or via calculation.
In
In
This information is presented on a computer monitor 50, though other display devices may be employed. Subsequent figures illustrate the display of preferred information, however, at this juncture, the various program code algorithms 20, 30, 40 for predictive ink usage/consumption will be described. While the program code algorithms 20, 30, 40 are collectively depicted in
In a first embodiment of the invention, usage data is collected empirically in small packages, i.e., histogram data, and subsequently extrapolated to develop data useful for predicting consumption. As used herein, the term “histogram” means a data sample or sampling of a statistically significant data set representative of the items to be printed. The number can be as few as several or several hundred, depending upon the total number of pieces to be printed. More specifically, in Step A, an initial ink level within an ink cartridge is determined. The initial ink level will typically begin with the level upon installation or “ink full”. Alternatively, the ink level may be that remaining subsequent to the previous print job. With respect to the latter, a conventional capacitance memory storage device or method may be employed to retain such historical ink level for subsequent use. In step B, a histogram of empirical data is obtained and evaluated based upon a threshold number of printed items. That is, by reviewing a threshold number of mailpieces X, e.g., 10, 50 or 100 mailpieces etc., an accurate prediction can be made concerning the number of remaining or additional mailpieces which can be printed based upon the ink remaining within the ink cartridge.
This methodology determines the ink usage with respect to printing a predetermined size of, for example, one hundred (100) mailpieces, i.e., X=100. Using this empirically derived data, a prediction can be made concerning the number of additional mailpieces which can be printed, assuming, of course, that the sample data is representative of the remaining pieces to be printed. While the described embodiment employs a threshold sample size of one-hundred (100) mailpieces, it will be appreciated that as more mailpieces are printed the histogram can be updated to improve the accuracy of the predicted values, i.e., the number of pieces which can be printed.
In
Returning to step C of
Alternatively, in steps F and G, by determining the print rate of the print job in step F, the time remaining until the ink cartridge is depleted can be determined in step G. Inasmuch as most conventional high-speed printers maintain print rate information which can be used to estimate or predict, based upon an evaluation of the print capacity remaining, the time remaining before ink within one of the ink cartridges is depleted. For example, based upon a print rate of 5,000 pieces/hr as seen in Column V of
In steps H-K, the information derived from the various evaluation steps above, e.g., number of items which may be printed, time remaining, sufficiency of ink, etc., can be displayed on a system monitor 50. In
While the histogram prediction methodology has been described in the context of a print job having a known quantity of mailpieces, the histogram methodology is particularly useful in determining the number of remaining items/mailpieces which can be printed, irrespective the number of items anticipated in any particular print job. That is, assuming that the items to be printed have similar characteristics, e.g., the information to be printed in each print zone is of similar font, size and style, then a histogram, which samples a threshold number of items to be printed, can accurately predict the number of items to be printed before an ink-out condition. Consequently, when the number of items of a print job is unknown, the histogram methodology provides a useful tool for providing a user/operator with information concerning which ink cartridge will be depleted before other ink cartridges. Additionally, an accurate estimate of the number of pieces which can be printed, i.e., by that and other ink cartridges, can be displayed/provided.
It will be appreciated that the above described histogram methodology is not entirely predictive inasmuch as the technique relies upon the collection of empirical data to extrapolate data necessary to predict the number of mailpieces which can be printed. In
In step M of
Similar to the previous histogram embodiment, the same steps C-G may be performed to evaluate and calculate the print capacity, sufficiency of ink, and time remaining before a particular cartridge is depleted of ink. Furthermore, the same information described in steps H-K may be displayed to advise a user/operator.
In yet another embodiment, a predictive ink usage software application can be employed to review the electronic version of the document i.e., the text and images to be printed, before being rendered by print driver software. Similar to the print stream methodology, each letter and image of a document can be reviewed to calculate the precise amount of ink which will be consumed to print the respective document. Upon combining the ink usage data associated with all documents to be printed, a highly accurate estimate can be obtained to determine whether the ink cartridges of each zone are adequately filled and/or which ink cartridge will be depleted before the others. In addition to determining whether a particular ink cartridge will be depleted before the completion of a print job, an estimate of the ink consumption can be obtained to properly allocate job costs or perform a cost estimate. Consequently, the predictive usage algorithms may be used to augment finance operations and estimates. Inasmuch as ink consumption is one of the principle factors which drive printing costs, the method provides the user with traceable and supportable cost allocation information.
In summary, various predictive methods provide a user/operator with data concerning the usage/consumption of ink during a print job. The method may employ empirically-derived or calculated data, directly from a print job to determine whether a print job can be completed with the currently-installed set of ink cartridges 14. Furthermore, a comparative analysis may be performed by evaluating the rate of ink consumption of each ink cartridge 14 based upon the ink usage data. That is, the comparative analysis can determine which of the ink cartridges 14 will be depleted before other ink cartridges 14 based upon the number of items which can be printed by each ink cartridge. For systems vary the print rate, i.e., wherein the printer provides or issues a print rate signal indicative of the number of items printed per unit time, the method may also determine the minimum time before an ink out condition. As such, the processor 10 will determine which ink cartridge 14 is associated with the minimum time before ink cartridge depletion and indicate, via the display 50 or other visual cueing device, which ink cartridge 14 will be depleted before other ink cartridges.
In addition to providing better operator oversight and management, the method also provides information useful for cost estimating and allocation. More specifically, a user/operator may determine, with a high degree of accuracy, the amount of ink which will be consumed to complete a print job. With this information, the user may provide accurate customer estimates or, more accurately, allocate costs across multiple print jobs.
Although the invention has been described with respect to a preferred embodiment thereof, it will be understood by those skilled in the art that the foregoing and various other changes, omissions and deviations in the form and detail thereof may be made without departing from the scope of this invention.