Image forming system and control device

Abstract

To provide a technique to save power required for an external controller of an image forming apparatus.SOLUTION: A DFE 201 causes an image forming apparatus 10 to form an image according to a print job. The DFE 201 comprises: an image processing unit 204 that generates image data from a print job; a first communication unit 206 that transmits the image data to the image forming apparatus 10 and acquires information on the progress of image formation from the image forming apparatus 10; and a power control unit 205 that, based on the progress information, determines whether to cause the DFE 201 to operate in a power saving mode in which power consumption is reduced compared to a normal operation state.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an external control device provided in an image forming apparatus and an image forming system including the image forming apparatus and the external control device.

Background Art

[0002] Conventionally, an image forming system including an image forming apparatus that forms an image on a recording material and a control device provided outside the image forming apparatus and connected to the image forming apparatus is known (Patent Document 1). The control device is sometimes called "DFE (Digital Front End)". The DFE in Patent Document 1 generates image data based on the content of a print job transmitted from an external device such as a PC (Personal Computer), and transmits the generated image data to the image forming apparatus. The image forming apparatus stores the image data acquired from the DFE in a memory, and performs a printing process based on the image data stored in the memory.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, if image data corresponding to a second print job is transmitted from the DFE to the image forming apparatus while the image forming apparatus is executing a first print job, the following problem may occur. Specifically, the remaining memory capacity in the image forming apparatus executing the first print job may be less than the data size of the image data corresponding to the second print job. In this case, for example, the DFE will stop transmitting the image data corresponding to the second print job and will resume transmitting the image data corresponding to the second print job when memory capacity becomes available in the image forming apparatus. During the period from when the transmission of image data corresponding to the second print job is stopped until it is resumed, power is supplied to the various components installed within the DFE. In other words, during the period from when the transmission of image data is stopped until it is resumed, unnecessary power is consumed in the DFE. As a result, the power consumption of the image forming system increases.

[0005] In view of the above-mentioned problems, the primary objective of the present invention is to provide a technology for reducing the power consumption of an external control device for an image forming apparatus. [Means for solving the problem]

[0006] The external control device of the present invention is an external control device for an image forming apparatus that causes an image forming apparatus to form an image according to a print job, and is characterized by comprising: an image processing means for generating image data from the print job; a communication means for transmitting the image data to the image forming apparatus and obtaining progress information of the image formation from the image forming apparatus; and a power control means for determining whether or not to operate the external control device in a second state with reduced power consumption compared to a first state, based on the progress information.

[0007] The present invention provides an image forming system comprising: an image forming apparatus for forming an image on a recording material; and an external control device for causing the image forming apparatus to form the image according to a print job, wherein the external control device comprises: an image processing means for generating image data from the print job; a communication means for transmitting the image data to the image forming apparatus and obtaining progress information on the formation of the image from the image forming apparatus; and a power control means for determining whether or not to operate the external control device in a second state with reduced power consumption compared to a first state, based on the progress information, wherein the image forming apparatus comprises: a job control means for obtaining the image data from the external control device and generating the progress information based on the obtained image data. [Effects of the Invention]

[0008] According to the present invention, power saving of the external control device for the image forming apparatus is achieved. [Brief explanation of the drawing]

[0009] [Figure 1] Diagram of the image forming system. [Figure 2] Configuration diagram of the control system. [Figure 3] (a) and (b) are diagrams illustrating the power saving control of the DFE. [Figure 4] A flowchart illustrating the process of transitioning to power-saving mode in DFE. [Figure 5] A flowchart illustrating the process of returning the DFE from power-saving mode to normal operation. [Modes for carrying out the invention]

[0010] Preferred embodiments of this invention will be described in detail below with reference to the drawings.

[0011] (Image forming apparatus) Figure 1 is a diagram showing the configuration of the image forming system in this embodiment. The image forming system comprises an image forming apparatus 10 and an external control device DFE 201. The image forming apparatus 10 has a printer controller 200. The printer controller 200 is communicated to the DFE 201 via a communication line 202. Details of the printer controller 200 will be described later.

[0012] Furthermore, the image forming apparatus 10 is equipped with an operation unit 1000 at its top. The operation unit 1000 is a user interface having an input interface and an output interface. The user can input predetermined instructions using the operation unit 1000. The input interface includes various keys and a touch panel, etc. The output interface includes a display and a speaker.

[0013] The image forming apparatus 10 forms an image on a sheet-like recording material S based on image data acquired from the DFE 201. The image forming apparatus 10 forms a color image using an electrophotographic method. To this end, the image forming apparatus 10 is equipped with multiple (four in this embodiment) image forming units Pa to Pd corresponding to multiple colors (four in this embodiment). The multiple image forming units Pa to Pd are arranged in a line along the rotation direction of the intermediate transfer belt 7.

[0014] The image forming units Pa to Pd each form images of different colors. In this embodiment, image forming unit Pa forms a yellow (Y) image. Image forming unit Pb forms a magenta (M) image. Image forming unit Pc forms a cyan (C) image. Image forming unit Pd forms a black (K) image. Image forming units Pa to Pd have the same configuration. In this embodiment, image forming units Pa to Pd corresponding to four colors are described, but they are not limited to four colors. Also, the arrangement of image forming units Pa to Pd is not limited to that shown in Figure 1.

[0015] The image forming units Pa to Pd comprise photoreceptors 1a to 1d, chargers 2a to 2d, exposure units 3a to 3d, developers 100a to 100d, primary transfer rollers 4a to 4d, and photoreceptor cleaners 6a to 6d. The photoreceptors 1a to 1d are drum-shaped, have a photosensitive layer on their surface, and rotate around the drum axis. The chargers 2a to 2d uniformly charge the surface of the rotating photoreceptors 1a to 1d. The exposure units 3a to 3d scan the surface of the charged photoreceptors 1a to 1d with laser light modulated based on image data. By scanning with laser light, an electrostatic latent image is formed on the surface of the photoreceptors 1a to 1d. The developers 100a to 100d develop the electrostatic latent image with a developer (toner) of the corresponding color. As a result, an image (toner image) of the corresponding color is formed on the photoreceptors 1a to 1d.

[0016] When the amount of toner stored in the developing units 100a to 100d decreases, toner is replenished from the toner storage sections Ta to Td via the corresponding toner replenishment device (not shown). When the amount of toner in the toner replenishment device decreases, toner is supplied from the toner storage sections Ta to Td. The developing units 100a to 100d contain a two-component developer, which is a mixture of non-magnetic toner and a magnetic carrier, or a one-component developer, which is magnetic toner or non-magnetic toner only. The toner containers Ta to Td are located above the image forming sections Pa to Pd.

[0017] The primary transfer rollers 4a to 4d form primary transfer sections T1a to T2d with an intermediate transfer belt 7 in between them and the corresponding photoreceptors 1a to 1d. The primary transfer rollers 4a to 4d transfer toner images from the photoreceptors 1a to 1d onto the intermediate transfer belt 7 when a predetermined pressure and electrostatic load bias are applied. The remaining toner on the photoreceptors 1a to 1d after transfer is collected by the photoreceptor cleaners 6a to 6d.

[0018] The intermediate transfer belt 7 is an endless belt provided on an intermediate transfer belt frame (not shown) and stretched over the secondary transfer inner roller 8, the tension rollers 17 and 18, and the secondary transfer upstream roller 19. The secondary transfer inner roller 8 rotationally drives the intermediate transfer belt 7 in the direction of arrow R7. Toner images are sequentially transferred onto the intermediate transfer belt 7 from the image forming units 1a to 1d so as to be superimposed as the belt rotates. As a result, a full-color toner image is formed on the intermediate transfer belt 7. By rotating, the intermediate transfer belt 7 conveys the carried toner image to the secondary transfer inner roller 8.

[0019] The image forming apparatus 10 includes a recording material storage 60 for storing the recording material S, a paper feed roller 61, a registration roller 62, and a secondary transfer outer roller 9. The recording material S is fed one by one from the recording material storage 60 by the paper feed roller 61 that employs a friction separation method. The paper feed roller 61 conveys the recording material S to the registration roller 62 via a conveyance path. The registration roller 62 corrects skewing of the recording material S and conveys the recording material S to the secondary transfer outer roller 9 in accordance with the timing at which an image is transferred from the intermediate transfer belt 7 to the recording material S.

[0020] The secondary transfer inner roller 8 and the secondary transfer outer roller 9 constitute the secondary transfer unit T2. The secondary transfer unit T2 sandwiches and conveys the intermediate transfer belt 7 and the recording material S by a transfer nip portion formed by the secondary transfer inner roller 8 and the secondary transfer outer roller 9. At this time, the secondary transfer unit T2 transfers the toner image carried by the intermediate transfer belt 7 onto the recording paper S conveyed from the registration roller 62 by applying a predetermined pressure and an electrostatic load bias. Transfer residual toner remaining on the intermediate transfer belt 7 after transfer is recovered by an intermediate transfer belt cleaner 11 disposed to face the tension roller 17.

[0021] The recording material S onto which the toner image has been transferred is conveyed to the fixing device 13 by the secondary transfer outer roller 9. The fixing device 13 includes a heating roller and a pressure roller. The fixing device 13 sandwiches and conveys the recording material S onto which the toner image has been transferred with a fixing nip formed by the heating roller and the pressure roller. At that time, the fixing device 13 heats and melts the toner image and crimps it to the recording material S. As a result, the image melts and adheres to the recording material S. For this purpose, the heating roller includes a heater serving as a heat source and is controlled so as to maintain an optimal temperature. The recording material S on which the image has been fixed is conveyed from the fixing device 13 to the discharge roller 64. The discharge roller 64 discharges the product, which is the recording material S on which the image has been fixed, outside the machine. As described above, the image forming apparatus 10 performs a printing process and creates a product.

[0022] (System controller) FIG. 2 is a configuration diagram of a control system that controls the operation of the image forming apparatus 10. The control system is composed of a printer controller 200 built in the image forming apparatus 10 and an external DFE 201. The printer controller 200 controls the operations of the components inside the image forming apparatus 10 for controlling the above-described printing process by the image forming apparatus 10. The DFE 201 is communicably connected to an external PC (Personal Computer) 203, which is an external device.

[0023] The DFE 201 includes an image processing unit 204, a power control unit 205, a first communication unit 206, a second communication unit 207, and a clock signal generation unit 208. The DFE 201 operates based on the clock signal generated by the clock signal generation unit 208. These functions are realized, for example, when a CPU (Central Processing Unit) or an MPC (Micro Processor Unit) executes a predetermined computer program. Further, these functions may be realized by an ASIC (Application Specific Integrated Circuit) or a combination of predetermined electronic components. A display 209 is connected to the DFE 201.

[0024] The second communication unit 207 is a communication interface that controls communication with the external PC 203. The second communication unit 207 acquires print jobs that instruct printing from the external PC. The image processing unit 204 performs predetermined image processing on the print jobs acquired by the second communication unit and generates image data suitable for printing by the image forming apparatus 10. The first communication unit 206 is a communication interface that controls communication with the printer controller 200 via the communication line 202. The first communication unit 206 transmits the image data generated by the image processing unit 204 to the printer controller 200. The power control unit 205 controls the power of the DFE 201. The power control unit 205 operates the DFE 201 in a power-saving mode that reduces power consumption compared to normal operation as needed.

[0025] The printer controller 200 includes a printer communication unit 215, a power control unit 216, a job control unit 210, a memory 211, a control unit 212, and an image processing unit 213. These functions are realized, for example, by a CPU or MPC executing a predetermined computer program. Alternatively, these functions may be realized by an ASIC or a combination of predetermined electronic components. An operation unit 1000 is also connected to the printer controller 200.

[0026] The printer communication unit 215 is a communication interface that controls communication with the DFE 201 via the communication line 202. The printer communication unit 215 acquires image data from the DFE 201. The job control unit 210 stores the image data acquired by the printer communication unit 215 in the memory 211 for each job. In this embodiment, the memory 211 has a predetermined capacity for storing image data. The image processing unit 213 performs predetermined image processing on the image data stored in the memory 211 and transmits it to the exposure unit 3.

[0027] The control unit 212 controls the printing process by the image forming apparatus 10. In this embodiment, the control unit 212 determines the number of print queues, which represents the number of print jobs, based on the information stored in the memory 211. The control unit 212 also calculates the job processing time, which is the time required to complete a print job, based on the information stored in the memory 211. The control unit 212 stores the number of print queues and the job processing time as print processing information in the memory 211. The print processing information includes the number of print queues, the job processing time, error information of the image forming apparatus 10, supply information such as toner level and paper level, and status information of the image forming apparatus 10, such as standby or printing. In other words, the print information is status information that indicates the printing status, including the progress of the printing process by the image forming apparatus 10. The print processing information is transmitted to the DFE 201 via the communication line 202 by the printer communication unit 215. The power control unit 205 of the DFE 201 determines whether or not to switch the DFE 201 to power saving mode based on the print processing information.

[0028] The control unit 212 transmits the job details (paper size, paper thickness, paper feed cassette) registered in the memory 211 to the engine control unit 214. The engine control unit 214 is connected to the transport unit 600, the image unit 110, the transfer unit 111, the fuser 13, and the exposure unit 3. The engine control unit 214 performs the printing process and produces the output by controlling the operation of these units based on the job details.

[0029] The transport unit 600 controls the transport of the recording material S by driving each roller used to discharge the recording material S from the recording material storage compartment 60 to the outside of the machine. The image formation unit 110 controls the operation of the image forming units Pa to Pd to form toner images on each photoreceptor 1a to 1d. The transfer unit 111 controls the operation of the primary transfer rollers 4a to 4d, the intermediate transfer belt 7, and the secondary transfer unit T2 to transfer the toner images formed on the photoreceptors 1a to 1d to the recording material S. The exposure unit 3 scans the photoreceptors 1a to 1d with a laser beam modulated based on image data acquired from the image processing unit 213 of the printer controller 200.

[0030] The power control unit 216 of the printer controller 200 controls the power state of the image forming apparatus 10. For example, if image data is not transmitted from the DFE 201 to the image forming apparatus 10 for a predetermined time or if there is no input from the operation unit 1000 for a predetermined time, the power control unit 216 switches the image forming apparatus 10 to a power-saving mode with lower power consumption than during normal operation. By switching to power-saving mode, the image forming apparatus 10 suppresses power consumption by cutting off the power supply to each component except for the control unit 212 and the printer communication unit 215.

[0031] (DFE operation) Figure 3 is an explanatory diagram of the power saving control of the DFE201. Figure 3(a) is a timing chart explaining the conventional operation. Figure 3(b) is a timing chart explaining the power saving control of this embodiment.

[0032] As described above, DFE201 converts print jobs acquired from the external PC203 into image data. DFE201 transmits the converted image data to the image forming apparatus 10. The image forming apparatus 10 forms an image on the recording material S based on the image data acquired from DFE201.

[0033] The job control unit 210 calculates the job processing time required to print a job when registering the job to the print queue. For example, the job control unit 210 calculates the job processing time for "Job 1" to be 10 minutes. The job processing time decreases as the printing process progresses. The job processing time increases as image data is acquired consecutively for "Job 2," "Job 3," and "Job 4." This is because the image data generation time by the DFE 201 is faster than the printing time by the image forming apparatus 10. In this embodiment, the DFE 201 switches to power-saving mode when the job processing time exceeds a first predetermined time (15 minutes or more in this embodiment), and returns from power-saving mode when the job processing time falls below a second predetermined time (less than 5 minutes in this embodiment). The first predetermined time (15 minutes in this embodiment) that triggers the transition to power-saving mode is longer than the second predetermined time (5 minutes in this embodiment) that triggers the return from power-saving mode.

[0034] In the conventional process shown in Figure 3(a), a delay occurs between the image data generation process by the DFE201 and the printing process by the image forming apparatus 10. The job processing time continues to increase because the interval for acquiring image data is shorter than the interval for completing a job. As a result, the print queue stored in the memory 211 of the printer controller 200 reaches the limit of what can be stored in the job storage area. In this case, the DFE201 experiences a waiting period during which it cannot send image data to the image forming apparatus 10. Since the DFE201 continues to operate during this waiting period, power is wasted.

[0035] In Figure 3(b), "Job 1" and "Job 2" result in a job processing time of 15 minutes or more. The job processing time is included in the print processing information and transmitted from the printer controller 200 to the DFE 201. The DFE 201 can detect the job processing time of the image forming apparatus 10 based on the print processing information. The power control unit 205 of the DFE 201 determines whether or not to switch to power saving mode based on the print processing information. Because the transmission of "Job 2" to the printer controller 200 results in a job processing time of 15 minutes or more, the power control unit 205 of the DFE 201 determines to switch from the normal power mode for job processing to a power saving mode that consumes less power than the normal power mode. In power saving mode, the DFE 201 temporarily suspends the conversion processing of print jobs by the image processing unit 204 and the transmission processing of image data to the image forming apparatus 10. Note that in power saving mode, the clock signal generation unit 208 may, for example, set the frequency of the clock signal to be lower than the frequency of the clock signal in normal power mode. Furthermore, in power-saving mode, the power control unit 205 may, for example, cut off power to the display 209 connected to the DFE 201 and which notifies the user of information regarding the processing content of the DFE 201. Even in power-saving mode, the DFE 201 can acquire print jobs from the external PC 203 and acquire print processing information from the image forming apparatus 10. In Figure 3(b), the DFE 201 acquires "Job 3" and "Job 4" in power-saving mode. Note that in power-saving mode, the frequency at which the DFE 201 acquires print processing information from the image forming apparatus 10 (polling frequency) may be lower than the frequency at which it acquires print processing information from the image forming apparatus 10 in normal power mode.

[0036] By switching to a power-saving mode that consumes less power than normal operation, the power consumption of the DFE201 can be reduced. Printing by the image forming apparatus 10 continues while in power-saving mode. When the job processing time becomes less than a second predetermined time (less than 5 minutes in this embodiment) due to the progress of the printing process, the power control unit 205 returns to normal power mode.

[0037] Once DFE201 has returned to normal operation, it resumes the conversion processing and image data transmission processing for "Job 3" and "Job 4" that it had acquired from the external PC 203. When the transmission of image data for "Job 4" is complete, DFE201 switches back to power-saving mode because the job processing time for the image forming apparatus 10 will exceed 15 minutes.

[0038] Thus, even when the image forming apparatus 10 is in the middle of printing, the DFE201 temporarily suspends processing and switches to power-saving mode according to the job processing time. As a result, the DFE201 can reduce wasted power consumption. The DFE201 can return from power-saving mode to display user operations or error and supply information acquired from the image forming apparatus 10. In this way, power consumption is reduced without compromising user convenience.

[0039] In this embodiment, job processing time is used as the condition for transitioning to power-saving mode, but the number of print queues registered in the image forming apparatus 10 may also be used as a transition condition. In other words, the DFE201 may transition to or return to power-saving mode based on the number of print queues included in the print processing information obtained from the image forming apparatus 10. In this case as well, the DFE201 can reduce power consumption, similar to when job processing time is used. For example, the DFE201 transitions to power-saving mode if the number of print queues is equal to or greater than a first predetermined number, and returns to normal operation when the number of print queues falls below a second predetermined number, which is less than the first predetermined number. In this way, the DFE201 transitions to and returns to power-saving mode by comparing the print processing information indicating the progress of printing in the image forming apparatus 10 with first and second predetermined times (first and second predetermined numbers) that serve as thresholds for transitioning to and returning to power-saving mode.

[0040] (Switching to power saving mode) Figure 4 is a flowchart illustrating the power-saving mode transition process of the DFE201. When DFE201 acquires a print job from the external PC203 (S401), it converts the acquired print job into image data (S402). DFE201 then transmits the image data generated by the conversion to the image forming apparatus 10 (S403).

[0041] The image forming apparatus 10 forms an image on the recording material S based on the image data acquired from the DFE 201. At this time, the printer controller 200 of the image forming apparatus 10 transmits print processing information, including the job processing time, to the DFE 201. The DFE 201 acquires the print processing information, including the job processing time, from the image forming apparatus 10 (S404). The DFE 201 determines whether or not the printing process by the image forming apparatus 10 has finished (S405). If the printing process is finished (S405:Y), the power saving transition process of the DFE 201 is terminated.

[0042] If the printing process does not finish (S405:N), DFE201 determines whether the job processing time is 100 minutes or more (15 minutes or more in this embodiment) (S406). If the job processing time is 100 minutes or more (S406:Y), DFE201 switches to power-saving mode and stops the process of converting the print job to image data and the process of transmitting the image data to the image forming apparatus 10 (S407). After that, DFE201 repeats the processes from S404 onwards until the job processing time is less than 200 minutes. If the job processing time is less than 100 minutes (less than 15 minutes in this embodiment) (S406:N), DFE201 continues the process of converting the print job to image data and the process of transmitting the image data to the image forming apparatus 10, and repeats the processes from S402 onwards.

[0043] (Returning from power saving mode) Figure 5 is a flowchart illustrating the process of returning the DFE201 from power-saving mode to normal operation. The DFE201 determines whether the job processing time in power-saving mode has fallen below the second predetermined time (less than 5 minutes in this embodiment) (S501). If the job processing time has fallen below the second predetermined time (S501:Y), the DFE201 returns from power-saving mode to normal operation mode and resumes the conversion of the print job to image data and the transmission of the image data to the image forming apparatus 10 (S502).

[0044] If the job processing time is 2 or more than the second predetermined time (5 minutes or more in this embodiment) (S501:N), the DFE201 checks whether there has been any user operation or a status change notification from the image forming apparatus 10 (S503). A status change notification is a notification that the operating state of the image forming apparatus 10 has changed. For example, when the image forming apparatus 10 changes state from power saving mode to normal operation, when an error (device abnormality) occurs, or when consumables such as toner or recording material S are consumed, the printer controller 200 sends a status change notification including the details to the DFE201. A status change notification is made, for example, by sending print processing information. User operation is input from the operation unit 1000 to the printer controller 200. If there is no user operation or status change notification (S503:N), the DFE201 maintains power saving mode and determines in the process of S501 whether the job processing time has become less than the second predetermined time (less than 5 minutes in this embodiment).

[0045] If there is a user operation or a status change notification (S503:Y), DFE201 performs a recovery operation from power saving mode similar to the process in S502 (S504). At this time, DFE201 determines whether the trigger for recovery from power saving mode is a user operation or the acquisition of a status change notification (S505). If the trigger is the acquisition of a status change notification (S505:Y), DFE201 instructs the external PC203 to display the contents of the status change notification for the image forming apparatus 10 (S506). DFE201 sends the status change notification for the image forming apparatus 10 to the external PC203 and displays the contents of the status change notification on the display. In this way, DFE201 notifies the user of the status change of the image forming apparatus 10.

[0046] If the trigger is a user operation (S505:N), the DFE201 measures the elapsed time since the last user operation. If the next user operation is performed within a predetermined time (S507:N), the DFE201 returns to the process in S503. If no user operation is performed for a predetermined time or longer (S507:Y), the DFE201 switches to power saving mode (S508).

[0047] In this way, the DFE201 decides whether to switch to power-saving mode and return to normal operation from power-saving mode based on print processing progress information such as job processing time and the number of print queues obtained from the image forming apparatus 10. In other words, the DFE201 decides whether or not to switch to power-saving mode based on the progress information. This type of control makes it possible to reduce the power consumption of the DFE201. Furthermore, even in power-saving mode, if the DFE201 receives notification of a change in the print status from the printer controller 200, this notification is sent to the user. Therefore, user convenience is not compromised even in power-saving mode.

[0048] If the progress information is job processing time, the DFE201 switches to power-saving mode and temporarily suspends image data generation and transmission if the job processing time is equal to or greater than the first predetermined time. The DFE201 returns from power-saving mode to normal operation mode and resumes image data generation and transmission when the job processing time falls below the second predetermined time. The second predetermined time is shorter than the first predetermined time.

[0049] If the progress information is the number of print queues, the DFE201 switches to power-saving mode and temporarily suspends image data generation and transmission if the number of print queues is equal to or greater than the first predetermined number. The DFE201 returns from power-saving mode to normal operation mode and resumes image data generation and transmission when the number of print queues falls below the second predetermined number. The second predetermined number is less than the first predetermined number.

[0050] In this embodiment, the DFE201 obtained the job processing time and print queue count from the image forming apparatus 10, but this is not limited to this. For example, the DFE201 may calculate the job processing time and print queue count based on the image data to be sent to the image forming apparatus 10, and decide whether or not to switch from normal power mode to power saving mode using the method described above.

[0051] Furthermore, in this embodiment, the DFE201 determines whether or not to switch from normal power mode to power-saving mode based on the job processing time and print queue number transmitted from the image forming apparatus 10, but this is not limited to this. For example, the control unit 212 may determine whether or not to switch from normal power mode to power-saving mode based on the job processing time and print queue number using the method described above, and the determination result may be output to the DFE201. The DFE201 may then switch the power mode from normal power mode to power-saving mode based on the determination result.

Claims

1. An image forming apparatus for forming an image on a recording medium; a control device that outputs a print job to the image forming device, the control device having, as power modes, a normal power mode in which the print job can be output, and a power saving mode that consumes less power than the normal power mode and does not output the print job; An image forming system having: The image forming apparatus includes: a storage means for storing a plurality of print jobs output from the control device; an image forming unit that forms an image on the recording medium based on the plurality of print jobs stored in the storage unit, The control device includes: when processing information relating to the amount of print jobs that have been received by the image forming device from the control device but have not yet been completed for image formation is greater than a first predetermined value while the power mode of the control device is the normal power mode, the print jobs that have not yet been output are not output to the image forming device, and the power mode is switched to a power saving mode; when the processing information is smaller than a second predetermined value that is smaller than the first predetermined value while the power mode of the control device is the power saving mode, transitioning the power mode to the normal power mode and outputting the print job that has not been output to the image forming device to the image forming device; 1. An image forming system comprising:

2. The image forming system described in Claim 1, characterized in that the processing information is data corresponding to the time required to complete a print job that has been received by the image forming device but for which image formation has not been completed.

3. The image forming system as described in claim 1, characterized in that the processing information is data corresponding to the number of print jobs that have been received by the image forming device but for which image formation has not been completed.

4. The image forming device outputs the processing information to the control device, 2. The image forming system according to claim 1, wherein the control device switches the power mode based on the processing information.

5. In the power saving mode, the control device outputs a request signal requesting the processing information to the image forming device at a first interval, and in the normal power mode, outputs the request signal to the image forming device at a second interval shorter than the first interval; 5. The image forming system according to claim 4, wherein the image forming device outputs the processing information to the control device based on the request signal.

6. The image forming system described in Claim 1, characterized in that the control device determines the processing information based on a print job output to the image forming device, and switches the power mode based on the determined processing information.

7. The image forming system described in claim 1, characterized in that the control device operates based on a clock signal of a first frequency in the power saving mode, and operates based on a clock signal of a second frequency greater than the first frequency in the normal power mode.

8. The image forming system as described in claim 1, further comprising a display device connected to the control device, wherein in the power saving mode, the display device is turned off.

9. The image forming system according to claim 1, characterized in that the control device is provided outside the image forming device.

10. A control device for outputting a print job to an image forming device which forms an image on a recording medium, the control device having a normal power mode in which the print job can be output, and a power saving mode which consumes less power than the normal power mode and does not output the print job, an output unit for outputting the print job; A control means for controlling the power mode; having when the power mode is the normal power mode, if processing information relating to the progress of a print job that has been output to the image forming device but image formation is not completed is greater than a first predetermined value, the print job that has not been output to the image forming device is not output, and the power mode is switched to the power saving mode; A control device characterized in that, when the power mode is the power saving mode, if the processing information is smaller than a second predetermined value which is smaller than the first predetermined value, the control device transitions the power mode to the normal power mode and outputs to the image forming device any print jobs that have not been output to the image forming device.

11. The control device according to claim 10, characterized in that the processing information is data corresponding to the time required to complete a print job that has been received by the image forming device but for which image formation has not been completed.

12. The control device according to claim 10, wherein the processing information is data corresponding to the number of print jobs that have been received by the image forming device but for which image formation has not been completed.

13. The control device according to claim 10, characterized in that the control device switches the power mode based on the processing information output from the image forming device.

14. The control device of claim 13, characterized in that in the power saving mode, the control device outputs a request signal requesting the processing information to the image forming device at a first interval, and in the normal power mode, the control device outputs the request signal to the image forming device at a second interval shorter than the first interval.

15. The control device described in Claim 10, characterized in that the control device determines the processing information based on a print job output to the image forming device, and switches the power mode based on the determined processing information.

16. The control device of claim 10, characterized in that in the power saving mode, the control device operates based on a clock signal of a first frequency, and in the normal power mode, the control device operates based on a clock signal of a second frequency greater than the first frequency.

17. The control device of claim 10, further comprising a display device connected to the control device, wherein in the power saving mode, the display device is turned off.

18. The control device according to claim 10, characterized in that the control device is provided outside the image forming device.

Images