Image forming system and image forming device

Abstract

To prevent power consumption from exceeding rated power when an image forming device is operated.SOLUTION: Control means is configured to compare third power consumption obtained by adding up first power consumption and second power consumption when image forming is performed by image forming means with a threshold upon receipt of a print instruction, and determine not to perform image forming by the image forming means if the third power consumption is greater than the threshold.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus, such as a copying machine, a printer, or a facsimile machine, that employs an electrophotographic or electrostatic recording system. [Background technology]

[0002] Conventionally, an image forming system in which a plurality of image forming devices are connected to one network is disclosed in Patent Document 1. Patent Document 1 discloses that when a print command is issued to a certain image forming device, it is determined whether or not to implement printing depending on whether or not the power consumption of the entire system exceeds a predetermined power. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 6-259359 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when considering a home as an example of the usage environment, depending on the relationship between the total power consumption of other devices in the home and the power consumption of the image forming device and the rated power of the power source in the home, there is a risk that the power consumption will exceed the rated power and cause the breaker to trip.

[0005] The present invention has been made in view of the above circumstances, and has an object to prevent power consumption of an image forming apparatus from exceeding its rated power when the image forming apparatus is operated. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, an image forming system is provided having an image forming device equipped with an image forming means for forming an image on a sheet and a control means for controlling the operation of the image forming means, and a power measuring device capable of communicating with the image forming device, to which one or more devices different from the image forming device are connected, and which transmits first power consumption of the one or more devices to the image forming device, wherein, when the control means receives a print command, it compares a third power consumption obtained by accumulating the first power consumption and a second power consumption when image formation is performed by the image forming means with a threshold value, and if the third power consumption is greater than the threshold value, it determines not to perform image formation by the image forming means. Effect of the Invention

[0007] It is possible to prevent the power consumption caused by operating the image forming apparatus from exceeding the rated power. [Brief description of the drawings]

[0008] [Figure 1] Schematic diagram of an image forming apparatus [Diagram 2] Block diagram showing an image forming apparatus and a power management device [Diagram 3] Diagram showing the display section where messages are displayed [Figure 4] A graph showing the trends in household electricity consumption [Diagram 5] Flowchart showing control of whether to execute printing [Figure 6] A graph showing the trends in household electricity consumption [Figure 7] Flowchart showing control of whether to execute printing DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments do not limit the invention according to the claims, and all of the combinations of features described in the embodiments are not necessarily essential to the solution of the invention. EXAMPLES

[0010] (Image forming device) FIG. 1 is a schematic diagram of an image forming apparatus 100. The operation of the image forming apparatus 100 will be described with reference to FIG. 1. The image forming apparatus 100 is an intermediate transfer type color printer using an intermediate transfer body 108. Note that an intermediate transfer type printer will be described here as an example, but a direct transfer type color printer or a monochrome printer may be used. The first station is a station for forming a yellow (Y) toner image, and the second station is a station for forming a magenta (M) toner image. The third station is a station for forming a cyan (C) toner image, and the fourth station is a station for forming a black (K) toner image. In the following description, the English letters Y, M, C, and K at the end of the reference symbols indicate that the corresponding members are related to the formation of yellow (Y), magenta (M), cyan (C), and black (K) toner images, respectively. In the following description, when it is not necessary to distinguish between colors, reference symbols without the English letters Y, M, C, and K at the end may be used.

[0011] A photosensitive drum 102 is disposed at each of the Y, M, C, and K stations. The photosensitive drum 102 is rotated by a driving force transmitted from a driving motor 120. The driving motor 120 rotates the photosensitive drum 102 in a counterclockwise direction. The chargers 103Y, 103M, 103C, and 103K include sleeves 103YS, 103MS, 103CS, and 103KS, respectively. The charger 103 charges the photosensitive drum 102.

[0012] The irradiation unit 104 selectively exposes the surface of the charged photosensitive drum 102 to light, thereby forming an electrostatic latent image on the photosensitive drum 102. The developing units 106Y, 106M, 106C, and 106K are equipped with sleeves 106YS, 106MS, 106CS, and 106KS, respectively. The developing units 106 develop the electrostatic latent image formed on the photosensitive drum 102 with toner of each color to form a toner image. Each of the developing units 106 is detachable.

[0013] A primary transfer bias is applied to the primary transfer roller 107, which primarily transfers the toner image formed on the photosensitive drum 102 at the primary transfer section onto the intermediate transfer belt 108. The toner images of each color are sequentially primarily transferred, forming a toner image (hereinafter also referred to as an image) in which the toner images of each color are superimposed on each other on the intermediate transfer belt 108. The image primarily transferred onto the intermediate transfer body 108 is transported to the secondary transfer section.

[0014] The sheets 130 stacked on the paper feed tray 101 are fed from the paper feed tray 101. The paper feed sensor 115 and the transport sensor 116 detect the sheets 130 fed from the paper feed tray 101. The sheets 130 are transported to the secondary transfer section, and a secondary transfer bias is applied to the secondary transfer roller 109, so that the image on the intermediate transfer belt 108 is secondarily transferred onto the sheet 130. The secondary transfer roller 109 performs the secondary transfer at the contact position 109a. During the period when the secondary transfer is not performed, the secondary transfer roller 109 can move to the separation position 109b. The toner remaining on the intermediate transfer body 108 is cleaned by the cleaning section 110. The cleaned waste toner is stored in a cleaner container.

[0015] The fixing section 111 includes a fixing roller 112 for heating the sheet 130 and a pressure roller 113 for pressing the sheet 130 against the fixing roller 112. The fixing roller 112 and the pressure roller 113 are formed in a hollow shape, and each has a heater 114 built in. The fixing section 111 conveys the sheet 130 carrying an unfixed image by the fixing roller 112 and the pressure roller 113, and applies heat and pressure to fix the image on the sheet 130. A temperature sensor (not shown) is attached to the fixing section, and the temperature required for fixing is controlled based on the detection result of the temperature sensor. The sheet 130 with the fixed image is discharged to a discharge tray by discharge rollers 131, and the image forming operation is completed.

[0016] (Block diagram) 2 is a block diagram showing the connection between the image forming apparatus 100 and the power management apparatus 220. In the figure, solid arrows indicate control signals, dashed arrows indicate power supplies, and dotted lines indicate paths for power information.

[0017] The CPU 201 as a control means reads out the control program and information stored in the storage unit 203, and controls various operations such as image formation on the sheet 130 by the image forming means of the image forming apparatus 100. The CPU 201 also controls the power supplied from the power supply unit 208 to the heater 114 of the fixing unit 111. The RAM 202 is composed of a volatile storage medium such as an SRAM or DRAM, and is used as a temporary storage area such as a work area of ​​the CPU 201. The storage unit 203 is composed of a non-volatile storage medium such as a flash ROM or HDD, and is used as a storage area for various data. The operation unit 204 includes a display unit 205. Information input by the user through the operation unit 204 is transmitted to the CPU 201. The CPU 201 controls the image forming apparatus 100 according to the input information. The display unit 205 displays messages according to the input information. The power supply unit 208 supplies power supplied from the outlet 207 to each unit in the image forming apparatus 100. A driving unit 209 drives a motor 210 in response to an instruction from the CPU 201 to transport the sheet 130. In the fixing unit 111, power is supplied to a heater 114 in response to an instruction from the CPU 201 to fix the image on the sheet 130.

[0018] The network I / F 206 is connected to the power management device 220 via a power communication network such as wirelessly or a power line, and can communicate control signals, power information, and the like. The power management device 220, which is a power measurement device, is also called a Home Energy Management System (HEMS). The HEMS is a power management system that connects to home appliances and electrical equipment, visualizes the amount of electricity, gas, and the like used on a monitor screen, and optimizes the home appliances through automatic control. The power management device 220 communicates with the image forming device 100 and other electrical appliances 230 such as home appliances to manage the total power consumption in the home in real time, and can transmit control signals and power information that instruct the image forming device 100 to switch to an energy saving mode.

[0019] (Power Consumption Limit Mode) In recent years, the number of people working from home has increased, and electrophotographic image forming devices that are generally used for business purposes are increasingly being used at home. However, there is a limit to the amount of power that can be used at home, and there is a risk of the breaker tripping if an electrophotographic image forming device is used in conjunction with other electrical appliances. In such an environment, it is effective to provide a power consumption limit mode as a power saving mode.

[0020] Next, the power consumption limit mode will be described. The power consumption limit mode is a setting for operating to suppress the maximum power consumption in a home, for example. The user can instruct the mode to be on / off from the operation unit 204. The image forming apparatus 100 acquires information on the power consumption (first power consumption) used by the other electric devices 230 from the power management device 220 via the network I / F 206, and controls the image forming operation.

[0021] When the power consumption limit mode is set to OFF, the image forming apparatus 100 executes printing based on print information (print JOB, print data) as a print command transmitted from a PC (external information terminal). When the power consumption limit mode is set to ON, the image forming apparatus 100 requests the power consumption from the power management apparatus 220 and receives the result.

[0022] The CPU 201 compares the total power consumption (third power consumption) obtained by integrating the power consumption used by the other electrical devices 230 and the power consumption (second power consumption) consumed by the image forming apparatus 100 during printing with a threshold value. If the total power consumption is equal to or less than the threshold value, the rated power will not be exceeded even if image formation is performed, so the CPU 201 executes image formation. As shown in FIG. 3(a), a message indicating that "printing" is being displayed on the display unit 205. The power consumption consumed during printing is stored in advance in the storage unit 203.

[0023] If the total power consumption is greater than the threshold, the CPU 201 does not allow image formation to be performed since performing image formation would exceed the rated power and there is a possibility that the breaker would trip. Then, the CPU 201 displays a message on the display unit 105 indicating that "printing is on hold due to power consumption limit" as shown in FIG. 3B. Note that the power consumption limit mode is switched on / off by the user via the operation unit 204 and the display unit 205. Information regarding the set mode is stored in the storage unit 203, and the CPU 201 can refer to the mode information from the storage unit 203.

[0024] Note that, as an example, a method of determining an image formation operation on the image forming apparatus 100 side as an image forming system will be described here, but the present invention is not limited to this. It is also possible for a device outside the image forming apparatus 100, such as the power management device 220, to determine the image formation operation and control the operation of the image forming apparatus 100 as an image forming system. In other words, the device outside the image forming apparatus 100 compares the total power consumption with a threshold value, and transmits information indicating whether or not to execute image formation to the image forming apparatus 100 based on the comparison result. The image forming apparatus 100 may control whether to execute or interrupt image formation based on the received information.

[0025] (Trends in power consumption) An example of the change in household power consumption from the start of printing by image forming apparatus 100 to the end of printing will be described with reference to Fig. 4. At T1, CPU 201 receives a print job and receives household power consumption from power management apparatus 220 via network I / F 206. CPU 201 calculates total power consumption by adding up the received power consumption and the power consumption during printing by image forming apparatus 100 that is stored in advance in storage unit 203, and compares it with a threshold value. At T1, the total power consumption is less than the threshold value, so CPU 201 starts printing the first page. By starting printing, household power consumption has increased by the amount of power consumed during printing.

[0026] At T2, CPU 201 finishes printing the first page. With the printing finished, the power consumption in the home is reduced by the amount of power consumed during printing. At T3, when printing the second page following the completion of printing of the first page, CPU 201 again receives the power consumption in the home from power management device 220. CPU 201 calculates the total power consumption by adding up the received power consumption and the power consumption during printing of image forming apparatus 100 that is stored in advance in storage unit 203, and compares it with a threshold value. At T3, the total power consumption is less than the threshold value, so CPU 201 starts printing the second page.

[0027] At T4, before printing of the second page is completed, household electrical appliances other than image forming apparatus 100 are turned on, increasing household power consumption. At T5, CPU 201 completes printing of the second page. As a result of the completion of printing, household power consumption is reduced by the amount of power consumed during printing.

[0028] At T6, when printing the third page following completion of printing the second page, CPU 201 again receives household power consumption information from power management apparatus 220. CPU 201 calculates the total power consumption and compares it with the threshold. At T6, the total power consumption is equal to or greater than the threshold, so CPU 201 does not print the third page and transitions image forming apparatus 100 to a print standby state. At T7, CPU 201 again receives power consumption information from power management apparatus 220 at regular time intervals. At T7, household electrical appliances other than image forming apparatus 100 are turned off, reducing power consumption.

[0029] At T8, the CPI 201 compares the total power consumption with the threshold value. At T8, the total power consumption is less than the threshold value, so the CPU 201 starts printing the third page. At T9, the CPU 201 ends printing the third page. When printing of all pages in the job is completed and there is no instruction to print the next page, the CPU 201 ends the printing operation.

[0030] (flowchart) 5 is a flowchart showing control of whether or not to execute printing in the image forming apparatus 100. In S501, when the power switch of the image forming apparatus 100 is turned on by the user, the CPU 201 transitions the image forming apparatus 100 to a standby state. In S502, the CPU 201 transmits a request for rated power to the power management apparatus 220 via the network I / F 206 in order to receive the rated power in the home. In S503, the CPU 201 receives the rated power in the home from the power management apparatus 220 via the network I / F 206. In S504, the CPU 201 sets 90% of the rated power in the home received in S503 as a threshold. Note that setting the threshold to 90% of the rated power is just an example, and the threshold can be set appropriately depending on how much surplus power is to be secured relative to the rated power.

[0031] In S505, CPU 201 receives a print job via network I / F 206. In S506, CPU 201 transmits a power information request instruction to power management apparatus 220 via network I / F 206 to receive power consumption in the home. In S507, CPU 201 receives the power consumption in the home from power management apparatus 220 via network I / F 206.

[0032] In S508, the CPU 201 obtains a total power consumption by integrating the power consumption in the home received in S507 and the power consumption during printing of the image forming apparatus 100 stored in advance in the storage unit 203, and compares the total power consumption with a threshold value. In S509, if the total power consumption is less than the threshold value, the CPU 201 proceeds to S510, and if it is equal to or greater than the threshold value, the CPU 201 proceeds to S511. In S510, the CPU 201 prints one page. In S511, the CPU 201 does not print one page, and proceeds to a print standby state. In S512, the CPU 201 maintains the print standby state for a certain period of time. In S513, the CPU 201 determines whether the page is the last page of the print job received in S505. If it is not the last page, the CPU 201 proceeds to S506, receives the power consumption in the home again, and updates the power consumption. If it is the last page, the print operation ends.

[0033] Although the example of printing one page in S510 has been described, the control method may be such that multiple pages are printed. The power consumption in the home is received from the power management device 220 via the network I / F 206, and the total power consumption is calculated by accumulating the power consumption during printing of the image forming device 100 stored in advance in the storage unit 203. The total power consumption is then compared with a threshold, and if the total power consumption is less than the threshold, multiple pages are printed. Also, the example of waiting for a certain period of time to wait for a change in the power consumption in the home in S512 has been described, but the frequency of receiving the power consumption can be set as appropriate.

[0034] Thus, in recent years, high-function power meters that have a communication function for communicating with devices called smart meters and a management function for managing the devices are beginning to spread in homes. These smart meters are equipped with wireless communication functions as communication functions and are connected to devices such as air conditioners, lighting devices, thermometers, and security devices installed in homes and offices. In addition, power management systems called HEMS, which connect to home appliances and electrical equipment to visualize the amount of electricity, gas, etc. used on a monitor screen, and optimize home appliances through automatic control, are also beginning to spread. With these, it is possible to obtain the power consumption in a home even in an environment where various home appliances are connected, such as a home. Therefore, if a user sends a print command to the image forming device 100 at a time when there is no room for the rated power, it is possible to suppress a situation in which the breaker trips due to the rated power of the home being exceeded by temporarily suspending printing.

[0035] In addition, since the image forming apparatus requires a certain amount of time to feed, print, and eject paper, it is difficult to suddenly stop printing while printing is in progress. If printing is suddenly stopped or power supply is suddenly cut off, paper jams, poor fixing, and other component failures may occur. Therefore, the power consumption in the home is received from the power management device 220 via the network I / F 206, and the total power consumption is calculated by accumulating the power consumption during printing of the image forming apparatus 100 that is stored in advance in the storage unit 203. Then, the total power consumption is compared with a threshold value, and if the total power consumption is less than the threshold value, printing is performed, thereby preventing the occurrence of a situation in which printing has to be suddenly stopped. EXAMPLES

[0036] In the first embodiment, a method for comparing the total power consumption and the threshold between printing operations was described. In the present embodiment, a method for comparing the total power consumption and the threshold during the next printing operation while the previous printing operation is in progress is described. Note that the same reference numerals are used for the same components as those in the first embodiment, such as the image forming apparatus 100, and detailed description thereof will be omitted here.

[0037] As in the first embodiment, a method of determining an image formation operation on the image forming apparatus 100 side as an image forming system will be described as an example here, but the present invention is not limited to this. It is also possible for a device outside the image forming apparatus 100, such as the power management device 220, to determine the image formation operation and control the operation of the image forming apparatus 100 as an image forming system. That is, the device outside the image forming apparatus 100 compares the total power consumption with a threshold value, and transmits information indicating whether or not to execute image formation to the image forming apparatus 100 based on the comparison result. The image forming apparatus 100 may control whether to execute or interrupt image formation based on the received information.

[0038] (Trends in power consumption) An example of the change in household power consumption from the start of printing by image forming apparatus 100 to the end of printing will be described with reference to Fig. 6. At T1, CPU 201 receives a print job and receives household power consumption from power management device 220 via network I / F 206. CPU 201 calculates total power consumption by adding up the received power consumption and the power consumption during printing by image forming apparatus 100 that is stored in advance in storage unit 203, and compares it with a threshold value. At T1, the total power consumption is less than the threshold value, so CPU 201 starts printing the first page. By starting printing, household power consumption increases by the amount of power consumed during printing.

[0039] At T2, when CPU 201 prints the second page successively after printing the first page, CPU 201 again receives household power consumption from power management device 220 before printing of the first page is finished. CPU 210 calculates the total power consumption and compares it with the threshold. At T2, the total power consumption is less than the threshold, so CPU 201 determines that printing of the second page is possible. At T3, when printing of the first page is finished, CPU 201 starts printing of the second page.

[0040] At T4, before printing of the second page is completed, household electrical appliances other than image forming apparatus 100 are turned on, increasing household power consumption. At T5, when printing of the third page is to be performed successively after printing of the second page is completed, CPU 201 again receives household power consumption information from power management apparatus 220 before printing of the second page is completed. CPU 201 calculates the total power consumption and compares it with the threshold. At T5, the total power consumption is equal to or greater than the threshold, so CPU 201 determines to wait without printing the third page. At T6, when CPU 201 finishes printing of the second page, it causes image forming apparatus 100 to transition to a print standby state without printing the third page.

[0041] At T7, CPU 201 receives the power consumption in the home from power management device 220 again at regular time intervals. At T7, power consumption is reduced as electrical devices in the home other than image forming device 100 are turned off. At T8, CPI 201 compares the total power consumption with a threshold. At T8, the total power consumption is less than the threshold, so CPU 201 starts printing the third page. At T9, CPU 201 finishes printing the third page. When printing of all pages in the job is completed and there is no instruction to print the next page, CPU 201 finishes the printing operation.

[0042] (flowchart) Fig. 7 is a flowchart showing whether or not printing is executed in the image forming apparatus 100. Note that, since S701 to S709 are similar to S501 to S509 in Fig. 5 of the previous embodiment 1, detailed description thereof will be omitted here.

[0043] In S709, if the total power consumption is less than the threshold, CPU 201 proceeds to S710, and if it is equal to or greater than the threshold, proceeds to S716. In S710, CPU 201 starts printing one page. In S711, CPU 201 again requests power management device 220 to transmit the power consumption before printing of one page is completed. In S712, CPU 201 receives the power consumption in the home from power management device 220. CPU 201 calculates the total power consumption by adding up the received power consumption and the power consumption of image forming apparatus 100 during printing that is stored in advance in storage unit 203.

[0044] In S713, CPU 201 compares the total power consumption with a threshold value. If the total power consumption is less than the threshold value, it determines that the next page can be printed, and if it is equal to or greater than the threshold value, it determines that printing of the next page should be suspended. In S714, when printing of one page is completed, the process proceeds to S715. In S715, CPU 201 determines whether or not this is the last page of the print job received in S705. If it is not the last page, the process proceeds to S506, where the household power consumption is received again. If it is the last page, the printing operation is terminated.

[0045] In S716, the CPU 201 does not print one page and transitions to a print standby state. In S717, the CPU 201 maintains the print standby state for a certain period of time and transitions to S706.

[0046] Although S710 and S714 have been described as an example of printing one page, the control method may be a method of printing multiple pages. The control method may be a method of receiving household power consumption from the power management device 220 while printing multiple pages, and comparing the total power consumption with a threshold value. Also, in S717, an example of waiting for a certain period of time to wait for a change in household power consumption has been described, but the frequency of receiving power consumption can be set appropriately.

[0047] In this way, if a user sends a print command to image forming apparatus 100 at a time when there is no margin for the rated power, interrupting the print can prevent a situation in which the rated power of the home is exceeded and the breaker trips. Also, by receiving the power consumption in the home from power management device 220 while the previous page is being printed and comparing the total power consumption with a threshold, it is possible to determine whether the next page can be printed before printing of the previous page is completed, thereby improving productivity. [Explanation of symbols]

[0048] 100 Image forming device 201 CPU 220 Power management equipment

Claims

1. An image forming apparatus including an image forming unit that forms an image on a sheet and a control unit that controls an operation of the image forming unit; an electric power measuring device capable of communicating with the image forming apparatus, connected to one or more devices different from the image forming apparatus, and transmitting first power consumption of the one or more devices to the image forming apparatus, The image forming system is characterized in that, when a print command is received, the control means compares a third power consumption, which is the sum of the first power consumption and the second power consumption when image formation is performed by the image forming means, with a threshold value, and if the third power consumption is greater than the threshold value, it determines not to perform image formation by the image forming means.

2. The image forming system according to claim 1, characterized in that, when the control means receives a print command, it compares a third power consumption obtained by accumulating the first power consumption after completing image formation of a first page and the second power consumption when the image forming means forms an image of a second page following the first page with the threshold value, and if the third power consumption is greater than the threshold value, it determines not to execute image formation of the second page by the image forming means.

3. The image forming system according to claim 1, characterized in that, when the control means receives a print command, it compares a third power consumption, which is an accumulation of the first power consumption during the period in which image formation of a first page is being performed and the second power consumption when the image forming means performs image formation of a second page following the first page, with the threshold value, and if the third power consumption is greater than the threshold value, it determines not to perform image formation of the second page by the image forming means.

4. The image forming system described in claim 1, characterized in that if the third power consumption is greater than the threshold, the control means receives the first power consumption again from the power measuring device and updates it, compares the third power consumption obtained by integrating the updated first power consumption and the second power consumption with the threshold, and if the third power consumption becomes less than the threshold, determines to perform image formation by the image forming means.

5. A display means for displaying a message is provided, 2. The image forming system according to claim 1, wherein the control means, when the image forming means is not performing image formation, causes the display means to display a message indicating that image formation is not being performed.

6. An input means for inputting a mode, The image forming system according to claim 1, characterized in that, when a power consumption limiting mode is selected by the input means and the print command is received, the control means compares the third power consumption with the threshold value, and if the third power consumption is greater than the threshold value, determines not to perform image formation by the image forming means.

7. 2. The image forming system according to claim 1, wherein the control unit determines to cause the image forming unit to perform image formation if the third power consumption is equal to or less than the threshold value.

8. an image forming means for forming an image on a sheet; A control unit for controlling an operation of the image forming unit, An image forming apparatus that receives first power consumption of one or more devices other than the image forming apparatus from a power measuring device to which the one or more devices are connected, The image forming device is characterized in that, when a print command is received, the control means compares a third power consumption, which is the sum of the first power consumption and the second power consumption when image formation is performed by the image forming means, with a threshold value, and if the third power consumption is greater than the threshold value, it determines not to perform image formation by the image forming means.

9. The image forming apparatus according to claim 8, characterized in that, when the control means receives a print command, it compares a third power consumption obtained by accumulating the first power consumption after completing image formation of a first page and the second power consumption when the image forming means forms an image of a second page following the first page with the threshold value, and if the third power consumption is greater than the threshold value, it determines not to execute image formation of the second page by the image forming means.

10. The image forming apparatus according to claim 8, characterized in that, when the control means receives a print command, it compares a third power consumption obtained by integrating the first power consumption during the period in which image formation of a first page is being performed and the second power consumption when the image forming means performs image formation of a second page following the first page with the threshold value, and if the third power consumption is greater than the threshold value, it determines not to perform image formation of the second page by the image forming means.

11. The image forming apparatus according to claim 8, characterized in that, if the third power consumption is greater than the threshold value, the control means receives the first power consumption again from the power measuring device and updates it, compares the third power consumption obtained by integrating the updated first power consumption and the second power consumption with the threshold value, and if the third power consumption becomes equal to or less than the threshold value, determines to perform image formation by the image forming means.

12. A display means for displaying a message is provided, 9. The image forming apparatus according to claim 8, wherein the control means, when the image forming means is not executing image formation, causes the display means to display a message indicating that image formation is not being executed.

13. An input means for inputting a mode, The image forming apparatus according to claim 8, characterized in that, when a power consumption limiting mode is selected by the input means and the print command is received, the control means compares the third power consumption with the threshold value, and if the third power consumption is greater than the threshold value, determines not to perform image formation by the image forming means.

14. 9. The image forming apparatus according to claim 8, wherein the control unit determines to cause the image forming unit to perform image formation if the third power consumption is equal to or less than the threshold value.

15. An image forming apparatus including an image forming unit that forms an image on a sheet and a control unit that controls an operation of the image forming unit; an image forming system having a power measuring device capable of communicating with the image forming apparatus, the power measuring device is connected to one or more devices different from the image forming device, and compares a third power consumption obtained by integrating a first power consumption of the one or more devices and a second power consumption when an image is formed by the image forming means with a threshold value, and transmits information indicating whether or not image formation is to be performed to the image forming device; The image forming system is characterized in that the control means does not cause image formation by the image forming means to be performed when the received information indicates that image formation will not be performed, and causes image formation by the image forming means to be performed when the received information indicates that image formation will be performed.

16. The image forming system described in claim 15, characterized in that if the third power consumption is greater than the threshold, the power measuring device updates the first power consumption, compares the third power consumption obtained by integrating the updated first power consumption and the second power consumption with the threshold, and if the third power consumption becomes equal to or less than the updated threshold, sends information to the image forming device indicating that image formation is to be performed.

17. A display means for displaying a message is provided, 16. The image forming system according to claim 15, wherein, when the received information indicates that image formation is not to be performed, the control means causes the display means to display a message indicating that image formation is not to be performed.

Images