Image forming apparatus that controls the number of printed sheets

An image forming apparatus is described. The image forming apparatus may be for printing sheets on the basis of a print instruction input therein, including: a limit quantity storage unit storing a predetermined limit quantity; an accounting storage unit storing an accounting for printing one sheet; and a printing authorization unit authorizing execution of printing, when the print instruction is input, after a quantity of a consumer product consumed by printing reaches the limit quantity stored in the limit quantity storage unit, on condition that a user pays a price obtained by multiplying the number of sheets which should have been continuously printed on the basis of the print instruction by the accounting with reference to the accounting storage unit.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2006-297974, filed on Nov. 1, 2006, the disclosures of which are hereby incorporated into the present application by reference.

TECHNICAL FIELD

The present invention relates to an image forming apparatus having a function for controlling the number of printed sheets.

BACKGROUND

For an office or the like, there is proposed an image forming apparatus having the so-called department control function for the number of copies, for preventing excess copying when a reserved number of copies set for copying exceeds the number of copiable sheets per department.

When the reserved number of copies exceeds the number of copiable sheets controlled by the department control function per department, this image forming apparatus displays a warning about this excess. After making copies by the number of copiable sheets, the image forming apparatus discards excess image data.

Due to this department control function, the image forming apparatus can prevent copying in excess of the number of copiable sheets previously allocated to each department, whereby the expenses can be saved in each department, and the user can be prompted to refrain from unnecessary copying.

If absolutely necessary image data are discarded when the reserved number of copies exceeds the number of copiable sheets, however, the image forming apparatus is not user-friendly. While all image data may conceivably be copied within the number of copiable sheets by using both surfaces of each copying sheet (the so-called DX (duplex) printing) or by copying image data for a plurality of sheets on a single surface of each sheet in a reduced size (the so-called N-in-1 printing), this may not be desirable for the user.

SUMMARY

One aspect of the present invention may provide an image forming apparatus capable of executing printing in excess of the number of printable sheets if necessary while maintaining an effect of a department control function.

The same or different aspect of the present invention may provide an image forming apparatus for printing sheets on the basis of a print instruction input therein, including: a limit quantity storage unit storing a predetermined limit quantity; an accounting storage unit storing an accounting for printing one sheet; and a printing authorization unit authorizing execution of printing, when the print instruction is input, after a quantity of a consumer product consumed by printing reaches the limit quantity stored in the limit quantity storage unit, on condition that a user pays a price obtained by multiplying the number of sheets which should have been continuously printed on the basis of the print instruction by the accounting with reference to the accounting storage unit.

DETAILED DESCRIPTION

Embodiments of one or more aspects of the present invention are now described with reference to the drawings.

First Embodiment

FIG. 1is a block diagram showing the structure of an image forming system including complex machines as examples of an image forming apparatus of one or more aspects of the present invention.

This image forming system includes a plurality of complex machines1connected to a LAN (local area network)2constructed in an office or the like. A personal computer (hereinafter referred to as “PC”)4for transmitting image data and an image formation (printing) command to each complex machine1and making the complex machine1execute print processing is connected to the LAN2.

Each complex machine1has a printing function for outputting an image based on the image data received from the PC4to each sheet, a copying function for reading a document image and reproducing the document image on the sheet, and a facsimile function for reading the document image and transmitting the data of the read document image to the exterior through a telephone line network5and outputting to the sheet an image based on image data transmitted from the exterior through the telephone line network5.

In order to implement these functions, the complex machine1includes a LAN I/F (interface)12for connecting the complex machine1with the LAN2, a scanning section13optically reading the document image, a printing section14outputting the image data to the sheet, a modem15for connecting the complex machine1with the telephone line network5, and a sheet ejection sensor16outputting a pulse signal (detection signal) in response to ejection of each sheet printed in the printing section14, as well as a CPU6, a ROM7, a RAM8and an EEPROM9for controlling these elements. The CPU6functions as a printing authorization unit.

The LAN I/F12, the scanning section13, the printing section14, the modem15, the sheet ejection sensor16, the CPU6, the ROM7, the RAM8and the EEPROM9are connected with one another through a bus line18, to be capable of transmitting/receiving data to/from one another.

The ROM7stores various control programs etc. executed by the CPU6.

The RAM8is used as a work area for temporarily storing data, a program and the like when the CPU6executes any of the control programs. For example, a printed sheet counter19for counting the number of sheets whose ejection has been detected by the sheet ejection sensor16(number of sheets printed in the printing section14), a table spreading area22for spreading data of a table21described later and temporarily holding the same and the like are set in this RAM8.

The EEPROM9stores the table21described later.

An operation section10as an example of a setting unit including operation keys etc. operated by the user and an LCD11as an example of a display unit displaying information such as the operating situation of the complex machine1are connected to the bus line18.

The complex machine1further includes a USB port (not shown) for connecting a USB memory20to the complex machine1. The complex machine1also includes a USB I/F17for connecting the USB memory20inserted into the USB port and the bus line18with each other.

The complex machine1has the so-called department control function. The department control function is a function for controlling the number of sheets subjected to image formation (printing) in the complex machine1per user (department) in an office or the like and preventing the user from excessive printing when the number of sheets subjected to image formation exceeds a prescribed limit number.

FIG. 2illustrates an example of the table21stored in the EEPROM9.

As shown inFIG. 2, numbers (limit numbers) of sheets image-formable (printable) in this complex machine1are allocated to three users A, B and C respectively in the table21as an example of a limit quantity storage unit and an accounting storage unit, in consideration of the fact that the frequency of use of the complex machine1varies with the user A, B or C. In other words, the limit numbers for the users A, B and C are set to 100, 50 and 70 respectively.

The table21stores numbers (cumulative numbers of printed sheets) of image formation executed by the users A, B and C in association with the users A, B and C respectively. When the user A has already executed printing on 80 sheets in the complex machine1, for example, the table21stores the number80as the cumulative number of printed sheets in association with the user A.

The table21also shows two types of unit prices to be paid by the users A, B and C per printing. A unit sheet price1is a price to be paid by each user for printing within the limit number, and a unit sheet price2is a price to be paid for printing in excess of the limit number. The unit sheet price2is set higher than the unit sheet price1. For example, the unit sheet prices1and2for the user A are set to 10 yen and 12 yen respectively. The unit sheet prices1and2are individually set for the users A, B and C in proportion to the limit numbers respectively. For example, the unit sheet price1for the user A is set to 10 yen, while that for the user B is set to 8 yen.

FIG. 4is a flow chart showing processing related to the department control function with reference to the number of printed sheets.

When any user operates the operation section10and inputs an instruction for image formation (may hereinafter be referred to also as printing) in the printing section14, for example, the CPU6determines that a print request is received (YES at S1). Alternatively, the print request (instruction command for image formation) may be input from the PC4or any other complex machine1along with the image data through the LAN2. The processing described below is not performed unless the print request is received (NO at S1).

When the print request is received, the CPU6determines whether or not the number of sheets scheduled for printing (number of sheets to be printed in response to the print request) is graspable (S2). More specifically, the CPU6checks whether or not the number of sheets scheduled for printing has been input through the operation section10, and determines that the number of sheets scheduled for printing is ungraspable if the same has not been input (NO at S2). If the number of sheets scheduled for printing has been input, on the other hand, the CPU6determines that the number of sheets scheduled for printing is graspable (YES at S2). If the print request is received from the PC4or any other complex machine1, the CPU6may grasp the number of sheets scheduled for printing from data on the number of sheets scheduled for printing received along with the print request, or may spread the image data into bitmap data for grasping the number of sheets scheduled for printing from the bitmap data.

If the number of sheets scheduled for printing is ungraspable (NO at S2), the CPU6then reads the table21stored in the EEPROM9and spreads the data of the table21in the table spreading area22. Thereafter the CPU6refers to the data of the table spreading area22, and acquires the limit number, the cumulative number of printed sheets and the unit sheet prices1and2(seeFIG. 2) for the user inputting the print request. If the cumulative number of printed sheets is less than the limit number, the CPU6makes the printing section14execute image formation (printing) on the basis of the image data. The sheet ejection sensor16outputs a pulse signal every time the printing section14performs printing and ejects a printed sheet. The CPU6increments (+1) the count of the printed sheet counter19provided in the RAM8in response to the pulse signal output from the sheet ejection sensor16. The count of the printed sheet counter19has been reset to zero before this processing has been started. The printing section14performs the printing until the sum of the cumulative number of printed sheets and the count of the printed sheet counter19reaches the limit number (S3). The unit sheet price1is charged per printed sheet in the printing up to the limit number.

When the printing is performed up to the limit number, the CPU6makes the LCD11display information indicating that the unit sheet price2higher than the unit sheet price1is applied to subsequent printing of the user and the accounting (price for the subsequent printing) is thereby increased (S5). In place of the display on the LCD11, the CPU6may notify the user of the increase of the accounting by a sound from a speaker (not shown).

If the number of sheets scheduled for printing is graspable (YES at S2), on the other hand, the CPU6reads the table21stored in the EEPROM9and spreads the data of the table21in the table spreading area22. Thereafter the CPU6refers to the data of the table spreading area22, and calculates the price (predicted accounting) required for performing printing by the number of sheets scheduled for printing (S4). If the number of sheets scheduled for printing is in excess of the limit number, the CPU6calculates the predicted accounting by summing up a within-limit price obtained by multiplying the number of sheets not exceeding the limit number by the unit sheet price1and an out-of-limit price obtained by multiplying the number of sheets exceeding the limit number by the unit sheet price2.

The CPU6displays the predicted accounting calculated at the step S4on the LCD11, or notifies the user of the predicted accounting by a sound from the speaker (S6)

After the display or the notification at the step S5or S6, the CPU6checks whether or not the user operates the operation section10and instructs cancellation of printing (S7).

If the user instructs cancellation, the CPU6terminates this series processing.

If the user instructs no cancellation, on the other hand, the CPU6makes the LCD11display an inquiry about whether or not to perform DX printing or N-in-1 printing in place of normal printing (printing image data corresponding to a single surface on the single surface of each sheet) (S8).

When the user operates the operation section10and selects DX printing or N-in-1 printing of the image data (YES at S9), the CPU6calculates the price (predicted accounting) in DX printing or N-in-1 printing (S10). More specifically, if the user selects DX printing, the CPU6sets a value (rounded off if not divisible) obtained by dividing the number of sheets scheduled for printing by 2 as the number of sheets scheduled for DX printing. If the number of sheets scheduled for DX printing exceeds the limit number, the CPU6calculates the predicted accounting by summing up the within-limit price obtained by multiplying the number of sheets not exceeding the limit number by the unit sheet price1and the out-of-limit price obtained by multiplying the number of sheets exceeding the limit number by the unit sheet price2. If the user selects N-in-1 printing for printing image data for four sheets on the single surface of each sheet in a reduced manner, for example, the CPU6sets a value (rounded off if not divisible) obtained by dividing the number of sheets scheduled for printing by 4 as the number of sheets scheduled for N-in-1 printing. Then, the CPU6calculates the predicted accounting for the number of sheets scheduled for N-in-1 printing, similarly to the case for the number of sheets scheduled for DX printing.

The CPU6makes the LCD11display the predicted accounting calculated at the step S10, or notifies the user of the predicted accounting by a sound from the speaker (S14).

After the display or the notification at the step S14, the CPU6checks whether or not the user operates the operation section10and instructs cancellation of printing (S15).

If the user instructs cancellation (YES at S15), the CPU6terminates this series processing.

If the user instructs no cancellation (NO at S15), on the other hand, the CPU6charges the aforementioned sum of the within-limit-price and the out-of-limit price in DX printing or N-in-1 printing as the user's accounting, and makes the printing section14execute DX printing or N-in-1 printing on condition that the user pays the sum (S16).

If the user operates the operation section10and selects neither DX printing nor N-in-1 printing for the image data (NO at S9), on the other hand, the CPU6sets normal printing (S11).

Thereafter the CPU6charges the aforementioned sum of the within-limit-price and the out-of-limit price to the user with reference to accounting information and limit information of the user, and makes the printing section14execute normal printing on condition that the user pays the sum (S12).

When printing is completed at the step S12or S16, the CPU6adds the count of the printed sheet counter19to the cumulative number of printed sheets held in the table spreading area22, and holds the sum in the table spreading area22as a new cumulative number of printed sheets. Then, the CPU6rewrites the table21stored in the EEPROM9on the basis of the updated data held in the table spreading area22(S13), and terminates this series processing.

If the user performs printing in excess of the limit number and the limit consumption rate by prescribed quantities, the CPU6may charge a higher price by raising the aforementioned unit sheet price2and the aforementioned unit toner price2stepwise.

In this complex machine1, the table21stores the predetermined limit quantity (limit number) as well as the accounting (unit sheet price) for printing a sheet. After the consumption (number of sheets) of the sheets consumed by printing based on the print instruction from the user reaches the limit quantity, the complex machine1authorizes execution of printing on condition that the user pays the price obtained by multiplying the number of sheets to be continuously printed on the basis of the print instruction by the accounting.

In other words, even if the number of consumer products consumed by printing based on the print instruction from the user reaches the limit quantity, the user can continuously print the excess in this complex machine1by paying the price corresponding to the excess.

Thus, when the consumption of the consumer products consumed by printing based on the print instruction from the user reaches the limit quantity, image data corresponding to the excess can be prevented from being discarded without printing.

However, the excess is printed not free of charge but on condition that the user pays the aforementioned price. Therefore, the user can be prompted to refrain from unnecessary printing.

Consequently, excess printing can be executed in the complex machine1if necessary, while maintaining the effect of the department control function.

Further, this complex machine1displays the price on the LCD11when the number of sheets scheduled for printing is graspable, whereby the user can recognize the price necessary for printing the excess. In addition, the user can select whether or not to print the excess by paying the price after confirming the price. Thus, the user can be further prompted to refrain from unnecessary printing.

The table21stores the accounting per user, whereby the complex machine1can control the number of printed sheets suitable for each user although the frequency of use of the complex machine1varies with the user.

Further, the user can set whether or not to form images for a plurality of sheets on each sheet (DX printing or N-in-1 printing) by operating the operation section10. If authorizing execution of DX printing or N-in-1 printing, therefore, the user can complete printing without paying the price or reduce the number of sheets for the excess, thereby reducing the consumption of the consumer products.

Second Embodiment

FIG. 3illustrates an example of another table23stored in the EEPROM9.

According to this embodiment, the EEPROM9stores the table23shown inFIG. 3, in place of the aforementioned table21.

In the table23as an example of the limit quantity storage unit and an accounting storage unit, consumption rates (limit consumption rates) of toner consumable in this complex machine1are allocated to the three users A, B and C in consideration of the fact that the frequency of use of the complex machine1varies with the user A, B or C. The term “toner consumption rate” denotes the ratio of the quantity of toner consumed by averagely printing a sheet to the quantity of toner consumed by printing the sheet with no space, and a reference toner consumption rate is generally set to 50%, for example. As shown inFIG. 3, the limit consumption rates for the users A, B and C are set to 5000%, 4000% and 3000% respectively.

The table23stores consumption rates (cumulative print consumption rates) of toner consumed by the users A, B and C by printing in association with the users A, B and C respectively. When the user A has already executed printing by 8000% in the complex machine1, for example, the table23stores 8000% as the cumulative print consumption rate in association with the user A.

The table23also shows two types of unit prices to be paid by the users A, B and C per printing (on the reference toner consumption rate (50%)). A unit toner price1is a price to be paid by each user for printing within the limit consumption rate, and a unit toner price2is a price to be paid for printing in excess of the limit consumption rate. The unit toner price2is set higher than the unit toner price1. For example, the unit toner prices1and2for the user A are set to 10 yen and 12 yen respectively. The unit toner prices1and2are individually set for the users A, B and C in proportion to the limit numbers respectively. For example, the unit toner price1for the user A is set to 10 yen, while that for the user B is set to 8 yen.

FIG. 5is a flow chart showing processing related to the department control function with reference to the toner consumption rate.

When any user operates the operation section10and inputs an instruction for image formation (may hereinafter be referred to also as printing) in the printing section14, for example, the CPU6determines that a print request is received (YES at S21). Alternatively, the print request (instruction command for image formation) may be input from the PC4or any other complex machine1along with image data through the LAN2. The processing described below is not performed unless the print request is received (NO at S21).

When the print request is received, the CPU6calculates the number of dots of an image to be formed on each sheet on the basis of the image data and calculates the toner consumption rate (necessary toner consumption rate) necessary for printing the image data on the basis of the number of dots (S22).

Then, the CPU6reads the table23stored in the EEPROM9, and spreads the data of the table23in the table spreading area22. Thereafter the CPU6refers to the data of the table spreading area22, compares a value (total consumption rate) obtained by adding the necessary toner consumption rate obtained at the step S22to the cumulative consumption rate, with the limit consumption rate, and determines whether or not the total consumption rate is within the limit consumption rate (S23).

If the total consumption rate is in excess of the limit consumption rate (NO at S23), the CPU6refers to the data of the table spreading area22, and calculates the price (predicted accounting) corresponding to the necessary toner consumption rate (S25) If the sum of the toner consumption rates necessary for printing first and second sheets and the cumulative consumption rate is still within the limit consumption rate but the limit consumption rate is exceeded when a toner consumption rate necessary for printing a third sheet is further added to the sum, for example, the CPU6calculates the predicted accounting by summing up a within-limit-price obtained by multiplying the unit toner price1by2(for two sheets) and an out-of-limit price obtained by multiplying the number of the third and subsequent sheets by the unit toner price2.

Then, the CPU6makes the LCD11display the predicted accounting calculated at the step S25(S26). In place of the display on the LCD11, the CPU6may notify the user of the predicted accounting by a sound from the speaker (not shown). If the total consumption rate is in excess of the limit consumption rate by printing up to the necessary toner consumption rate, the CPU6makes a display or a notification for prompting the user to select whether or not to continue printing.

After the display or the notification at the step S26, the CPU6checks whether or not the user operates the operation section10and instructs cancellation of printing (S24). If the total consumption rate is within the limit consumption rate (YES at S23), the CPU6immediately checks whether or not the user instructs cancellation of printing (S24).

If the user instructs cancellation (YES at S24), the CPU6terminates this series processing.

If the user instructs no cancellation, the CPU6charges the aforementioned sum of the within-limit-price and the out-of-limit price to the user with reference to the aforementioned accounting information and limit information of the user, and makes the printing section14execute printing on condition that the user pays the sum (S27). In this printing, normal printing, DX printing or N-in-1 printing may be selectively executed.

In the printing at the step S27, the sheet ejection sensor16outputs a detection result (pulse data) to the printed sheet counter19of the RAM8every time a printed sheet is ejected, so that the CPU6counts the number of printed sheets and stores information on the number of printed sheets in the printed sheet counter19(S28).

Unless the printing is completed (NO at S29), the CPU6repeats the processing through the steps S22to S29.

When the printing is completed (YES at S29), the CPU6adds a value obtained by multiplying the number of printed sheets counted in the printed sheet counter19by the reference toner consumption rate (50%) to the cumulative printing consumption rate held in the table spreading area22, and holds the resulting sum in the table spreading area22as a new cumulative printing consumption rate. Then, the CPU6rewrites the table23stored in the EEPROM9on the basis of the updated data held in the table spreading area22, and terminates this series processing.

Also according to this embodiment, effects similar to those of the aforementioned embodiment (processing shown inFIG. 4) can be attained.

Third Embodiment

FIG. 6is a flow chart showing processing related to a department control function with reference to both of the number of printed sheets and a toner consumption rate.

According to this embodiment, the EEPROM9stores both of the tables21and23as shown inFIG. 1under the condition that both of sheets and toner are consumer products, for putting limitations when consumptions of these consumer products exceed limit consumptions.

Referring toFIG. 6, when any user operates the operation section10and inputs an instruction for image formation (may hereinafter be referred to also as printing) in the printing section14, the CPU6determines that a print request is received (YES at S31). Alternatively, the print request (instruction for image formation) may be input from the PC4or any other complex machine1along with image data through the LAN2. The processing described below is not performed unless the print request is received (NO at S31).

When the print request is received, the CPU6calculates the number of sheets scheduled for printing from the image data. Then, the CPU6reads the table21stored in the EEPROM9, and spreads the data of the table21in the table spreading area22. Thereafter the CPU6refers to the data of the table spreading area22, and acquires the limit number, the cumulative number of printed sheets and the unit sheet prices1and2(seeFIG. 2) for the user inputting the print request.

If the cumulative number of printed sheets is less than the limit number (YES at S32), the CPU6calculates the number of dots of an image to be formed on each sheet on the basis of the image data and calculates the toner consumption rate (necessary toner consumption rate) necessary for printing the image data on the basis of the number of dots (S33).

Then, the CPU6reads the table23stored in the EEPROM9, and spreads the data of the table23in the table spreading area22. Thereafter the CPU6refers to the data of the table spreading area22, compares a value (total consumption rate) obtained by adding the necessary toner consumption rate obtained at the step S33to the cumulative consumption rate, with the limit consumption rate, and determines whether or not the total consumption rate is within the limit consumption rate (S37).

If the total consumption rate is in excess of the limit consumption rate (NO at S37), the CPU6refers to the data of the table spreading area22, and calculates the price (predicted accounting) corresponding to the necessary toner consumption rate (S38). Since this calculation is similar to that at the step S25shown inFIG. 5, detailed description thereof is omitted.

The CPU6makes the LCD11display the predicted accounting calculated at the step S38(S39). In place of the display on the LCD11, the CPU6may notify the user of the predicted accounting by a sound from the speaker (not shown). If the total consumption rate is in excess of the limit consumption rate by printing up to the necessary toner consumption rate, the CPU6makes a display or a notification for prompting the user to select whether or not to continue printing.

If determining that the cumulative number of printed sheets is in excess of the limit number at the step S32, on the other hand, the CPU6refers to the data of the table21spread in the table spreading area22, and calculates the price (predicted accounting) corresponding to the number of sheets scheduled for printing (S34). Since this calculation is similar to that at the step S4shown inFIG. 4, detailed description thereof is omitted.

The CPU6makes the LCD11display the predicted accounting calculated at a step S34(S35). In place of the display on the LCD11, the CPU6may notify the user of the predicted accounting by a sound from the speaker (not shown). If the total consumption rate is in excess of the limit consumption rate by printing up to the necessary toner consumption rate, the CPU6makes a display or a notification for prompting the user to select whether or not to continue printing.

After the display or the notification at the step S35or the step S39, the CPU6checks whether or not the user operates the operation section10and instructs cancellation of printing (S36).

If the user instructs cancellation, the CPU6terminates this series processing.

If the user instructs no cancellation, on the other hand, the CPU6makes the printing section14execute printing on condition that the user pays the price (S40). The user must pay the price (accounting) corresponding to the number of sheets scheduled for printing if the CPU6determines that the cumulative number of printed sheets is in excess of the limit number at the step S32, or must pay the price corresponding to the necessary toner consumption rate if the cumulative number of printed sheets is within the limit number.

In the printing at the step S40, the sheet ejection sensor16outputs a detection result (pulse data) to the printed sheet counter19of the RAM8every time a printed sheet is ejected, so that the CPU6counts the number of printed sheets and stores information on the number of printed sheets in the printed sheet counter19(S41).

Unless the printing is completed (NO at S42), the CPU6repeats the processing through the steps S32to S42.

When the printing is completed (YES at S42), the CPU6adds the count of the printed sheet counter19to the cumulative number of printed sheets held in the table spreading area22and holds the resulting sum in the table spreading area22as a new cumulative number of printed sheets. Then, the CPU6rewrites the table21stored in the EEPROM9on the basis of the updated data held in the table spreading area22. Further, the CPU6adds a value obtained by multiplying the number of printed sheets counted in the printed sheet counter19by the reference toner consumption rate (50%) to the cumulative print consumption rate held in the table spreading area22, and holds the resulting sum in the table spreading area22as a new cumulative print consumption rate. Then, the CPU6rewrites the table21stored in the EEPROM9on the basis of the updated data held in the table spreading area22, and terminates this series processing.

Also according to this embodiment, effects similar to those of the aforementioned embodiments (processing shown inFIG. 4and that shown inFIG. 5) can be attained.

For example, the CPU6rewrites the value obtained by adding the count of the printed sheet counter19to the cumulative number of printed sheets as a new cumulative number of printed sheets in the table21without rewriting the limit number at each of the aforementioned steps S13and S42, whereby a value obtained by subtracting the cumulative number of printed sheets from the limit number corresponds to the number of image-formable (printable) sheets for next printing. Alternatively, the CPU6may rewrite a value obtained by subtracting the count of the printed sheet counter19from the limit number, as a new limit number. In other words, if the limit number is decremented every count of the printed sheet counter19during printing, the updated limit number corresponds to the number of image-formable sheets. In this case, the table21may not store the cumulative number of printed sheets. Similarly to this rewriting in the table21, the CPU6may rewrite the limit consumption rate in place of the cumulative print consumption rate in the table23at each of the aforementioned steps S29and S42.

The embodiments described above are illustrative and explanatory of the invention. The foregoing disclosure is not intended to be precisely followed to limit the present invention. In light of the foregoing description, various modifications and alterations may be made by embodying the invention. The embodiments are selected and described for explaining the essentials and practical application schemes of the present invention which allow those skilled in the art to utilize the present invention in various embodiments and various alterations suitable for anticipated specific use. The scope of the present invention is to be defined by the appended claims and their equivalents.