JP2008296391A - Image forming apparatus and system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which can reduce a power consumption at the time of returning from a power-saving state by performing image processing lowering a working frequency of a CPU within a return time until it becomes a printable state when it receives a printing job in a power state. <P>SOLUTION: The image forming apparatus 10 is equipped with an image processing part 11 which carries out image processing to the printing job and expands to printable raster data, a return time calculating part 12 which calculates the return time until the image forming apparatus 10 returns to the printable state from the power-saving state, a job amount calculating part which calculates a job amount of the printing job received at the image processing part 11 when the apparatus is in the power-saving state, and a frequency control part which controls the working frequency of the CPU equipped in the image processing part 11. The frequency control part calculates the lowest working frequency whereby image processing of the job amount can be completed within the return time, and controls the CPU to operate by the working frequency. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and system, and more particularly to an image forming apparatus and an image forming system equipped with a power saving function such as a sleep mode for reducing power consumption.

  In recent years, image forming apparatuses such as MFPs (digital multi-function peripherals) are becoming increasingly faster, more functional, and more multifunctional. In response to such demands for speeding up, a plurality of high-speed and large-capacity memories (SDRAMs) are mounted, and the power consumption of this memory is large in the power consumption of the entire image forming apparatus. It was.

  To deal with such a problem, for example, Patent Document 1 describes a method of determining a memory area necessary for raster data processing of image data and activating only the necessary memory area. According to this, since only the minimum necessary memory area can be maintained in the active state, power consumption can be reduced.

  On the other hand, the image forming apparatus as described above includes an interface controller that receives print data, a printer controller (image processing unit) that generates a print image and controls the entire apparatus, and a printer engine (image formation) that actually performs printing. Part). Generally, it is known that the power consumption of a printer controller having a CPU and a printer engine having a fixing device is large. In view of this, such an image forming apparatus is in a print waiting state, that is, when a predetermined time elapses after no print data is supplied from a host computer or the like, the power to the printer controller and the printer engine, particularly the CPU and the fixing device. It is equipped with a sleep mode that stops power supply and reduces power consumption.

  A transition instruction to the sleep mode and a release instruction for returning to the normal state from the sleep mode are controlled by the interface controller and the printer controller. That is, when a predetermined time elapses after the power is turned on or after the print processing is completed and the next print data is not received from the host computer or the like, the power supply to the printer controller or the printer engine is stopped, and then in the sleep state, When print data is received, power supply to the printer controller and printer engine is started.

  When returning from such a sleep mode or preheating mode, it takes a long recovery time until the image forming apparatus is in a printable state, that is, until the fixing unit of the printer engine is warmed up to a printable temperature. Therefore, when a print job is received in the sleep mode, image processing (development to raster data, etc.) is performed on the print job during the return time, and after the fixing device is warmed up and returned to a printable state, A printing process is executed.

  FIG. 8 is a diagram for explaining the relationship between power consumption and image processing time when a print job is received in the sleep mode in a conventional image forming apparatus. In the figure, (1) indicates that the image is being processed, and (2) indicates that the image forming apparatus is waiting for return. When the image forming apparatus receives a print job from a host computer or the like while in the sleep mode, the image forming apparatus cancels the sleep mode and starts a process for returning to a printable state. That is, power is supplied to the printer controller and the printer engine, and warm-up of the fixing device provided in the printer engine is started. The received print job is subjected to image processing by the printer controller and developed into raster data.

Usually, the time (2) required for warming up the fixing device is longer than the time (1) required for image processing. Therefore, after the image processing of (1) is completed first, after a while, the warming up of (2) is performed. The processing is completed, and the image forming apparatus is ready for printing.
JP 2004-351732 A

  However, in FIG. 8 described above, the image processing of (1) is executed by the CPU of the printer controller. Once the print job is received and the sleep mode is canceled, the power supply to the CPU is started. The operating frequency is maintained at a constant level. Accordingly, during the warm-up of (2) after the completion of the image processing of (1), the CPU continues to be energized even though it is not performing arithmetic processing, and when returning from the sleep mode. Was wasting power.

  The present invention has been made in view of the above circumstances, and when a print job is received in a power-saving state, the operating frequency of the CPU is lowered within the return time until the printable state is obtained. An object of the present invention is to provide an image forming apparatus and an image forming system capable of reducing power consumption when performing image processing and returning from a power saving state.

  In order to solve the above-described problem, a first technical means of the present invention includes an image processing unit that performs image processing on a print job and develops the raster data into printable raster data, and an image based on the raster data developed. An image forming apparatus that performs formation, and a return time calculation unit that calculates a return time until the image forming apparatus returns from a power saving state to a printable state, and an image processing unit that receives the time when the image forming apparatus is in a power saving state A job amount calculation unit that calculates the job amount of a print job and a frequency control unit that controls the operating frequency of the CPU included in the image processing unit, and the frequency control unit completes the image processing of the job amount within the return time The lowest possible operating frequency is calculated, and the CPU is controlled to operate at the operating frequency.

  According to a second technical means, in the first technical means, the return time calculating unit takes a time from when the image forming apparatus receives a print job in a power saving state to when the image forming apparatus rises to a printable fixing temperature. Is calculated as a return time.

  The third technical means includes a power control unit that, in the first or second technical means, specifies a circuit unnecessary for image processing by the image processing unit and stops or restricts power supply to the specified unnecessary circuit. It is characterized by that.

  According to a fourth technical means, in any one of the first to third technical means, when an additional print job is received during image processing by the image processing unit, the job amount calculation unit accepts the image processing unit. Recalculate the job amount of all print jobs, and the frequency control unit recalculates the lowest operating frequency that can complete the image processing of all the job amounts within the return time, and operates the CPU so as to operate at the operating frequency. It is characterized by controlling.

  A fifth technical means includes an image processing time calculation unit that calculates an image processing time required for image processing of a print job accepted by the image processing unit in any one of the first to fourth technical means, The image processing start timing for starting the image processing for the print job is adjusted based on the image processing time calculated by the time calculating unit.

  The sixth technical means is the fifth technical means in which the image processing start timing is changed stepwise from the time when the image processing unit accepts the print job, and the power consumption required for the image processing is compared at each timing. The timing at which the power consumption is lowest is determined as the image processing start timing.

  According to the seventh technical means, in any one of the first to fourth technical means, when it is not necessary to immediately output the print job received by the image processing unit, the image processing by the image processing unit is performed at the minimum necessary amount. It is characterized by being performed with power consumption.

  The eighth technical means includes the fixing device heated to a predetermined fixing temperature in the seventh technical means, and the time required for image processing performed with the minimum necessary power consumption is longer than the return time. The timing for starting heating the fixing device is shifted by a predetermined time immediately after the power saving state is released.

  According to a ninth technical means, in any one of the first to eighth technical means, the power saving state is a sleep mode in which the power consumption of the image forming apparatus is a predetermined value or less. is there.

  A tenth technical means is an image forming system including an information processing apparatus that transmits a print job and an image forming apparatus that forms an image based on the print job from the information processing apparatus. The image forming apparatus includes a job amount calculating unit that calculates a job amount of a print job to be transmitted to the image forming apparatus, the image forming apparatus receiving a print job and the job amount from the information processing apparatus, and image processing for the print job. An image processing unit that develops into printable raster data, a return time calculation unit that calculates a return time until the image forming apparatus returns from a power saving state to a printable state, and an operation of a CPU included in the image processing unit A frequency control unit that controls the frequency, and the frequency control unit calculates the lowest operating frequency at which the image processing of the job amount can be completed within the return time. It is obtained by and controls the CPU to work.

  According to an eleventh technical means, in the tenth technical means, the information processing apparatus includes an image processing time calculating unit that calculates an image processing time required for image processing of a print job transmitted to the image forming apparatus. The image processing start timing for starting the image processing for the print job is adjusted based on the image processing time calculated by the image processing time calculation unit.

  According to the present invention, when a print job is received in the power saving state, image processing can be performed with the CPU operating frequency lowered within the return time until the printable state is reached. It is possible to reduce power consumption when returning from the power.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of an image forming apparatus and an image forming system of the invention will be described with reference to the accompanying drawings. Note that the power saving state in the present invention means a power saving mode, that is, a mode in which power consumption is reduced most among modes that automatically shift after a predetermined time has elapsed in the standby state. The power consumption is controlled to be equal to or less than a certain value. The power saving state includes various names such as a sleep mode, a power save mode, a power saving mode, a preheating mode, an energy saving mode, and a low power mode, and includes all these modes.

  FIG. 1 is a block diagram showing a configuration example of an image forming system according to an embodiment of the present invention. In FIG. 1, 1 is an external information processing apparatus such as a PC (personal computer), and 10 is an image forming apparatus such as an MFP. Show. The image forming apparatus 10 performs image processing on a print job and develops the raster data into printable raster data, and the image forming apparatus 10 is in a printable state from a power saving state (hereinafter represented by a sleep mode). The return time calculation unit 12 that calculates the return time until the printer returns to the state, the fixing temperature measurement unit 13 that measures the fixing temperature of the fixing device 171, and a touch panel and operation key group for inputting operation information from the user. An operation information input unit 14 configured, an information display unit 15 configured by a liquid crystal display or the like for displaying various information such as an apparatus state, and an image reading unit 16 that optically reads a document image and inputs image data. An image forming unit 17 that forms an image based on raster data developed by the image processing unit 11, and a main control unit 18 that controls the entire image forming apparatus 10. Equipped with a.

  In the present embodiment, the image forming system includes an image forming apparatus 10 and at least one external information processing apparatus 1. The image forming apparatus 10 is connected directly to the external information processing apparatus 1 via a cable or via a network, and receives a print job generated by the external information processing apparatus 1. Then, the received print job is subjected to image processing and developed into printable raster data, and image formation is performed based on the developed raster data.

  In FIG. 1, the image forming unit 17 includes a fixing device 171 that is heated to a predetermined fixing temperature. When the image forming apparatus 10 shifts to the sleep mode, power supply to the image processing unit 11 and the image forming unit 17 is stopped or restricted. When a print job is received in the sleep mode, power supply to the image processing unit 11 and the image forming unit 17 is started, and warming up of the fixing device 171 is started. This warm-up process ends when heated to a predetermined fixing temperature, and then the image forming apparatus 10 is ready for printing.

When the image forming apparatus 10 receives a print job in the sleep mode, the fixing temperature measuring unit 13 measures the fixing temperature of the fixing device 171 at that time. Then, the return time calculation unit 12 calculates the time from the fixing temperature measured by the fixing temperature measurement unit 13 until the fixing temperature at which the image forming apparatus 10 can perform printing becomes the return time t. This return time t can be calculated by the following equation.
t = (d0−d) / Δd (1)
However, Δd is a rising temperature per unit time of the fixing device 171, d is a current fixing temperature, and d 0 is a fixing temperature at which the image forming apparatus 10 can print.

Further, assuming that the power consumption per unit time of the CPU provided in the image processing unit 11 is g (ω), the power consumption W at the return time t can be calculated by the following equation.
W = g (ω) · t Equation (2)
Here, ω is an operating frequency of the CPU provided in the image processing unit 11, and g (ω) is a function representing power consumption per unit time at the operating frequency ω. Note that g (ω) differs depending on the system, and can be expressed as g (ω) = b (proportional coefficient) · ω, for example.

  FIG. 2 is a block diagram illustrating a configuration example of the image processing unit 11 illustrated in FIG. In the figure, an image processing unit 11 includes a CPU 111 that controls image processing in the image processing unit 11, a storage unit 112 that is a semiconductor memory such as a ROM and a RAM, and a print that is received by the image processing unit 11 when in the sleep mode. A job amount calculation unit 113 that calculates the job amount of a job, an image processing time calculation unit 114 that calculates an image processing time required for image processing of a print job accepted by the image processing unit 11, and an external device (external information processing apparatus 1) The external I / F 115 corresponding to the receiving means of the present invention for connection to the HDD, the HDD 116 which is a hard disk for storing image data, etc., and a circuit unnecessary for image processing by the image processing unit 11 are specified and specified. A power control unit 117 for stopping or limiting power supply to the unnecessary circuit, and frequency control for controlling the operating frequency of the CPU 111 And a 118.

  The job amount calculation unit 113 calculates the data amount of the print job, that is, the job amount from information such as the number of pages and the number of pixels of the print job received by the image processing unit 11 in the sleep mode.

The frequency control unit 118 calculates the lowest operating frequency at which the image processing of the job amount calculated by the job amount calculating unit 113 can be completed within the return time calculated by the return time calculating unit 12. The CPU 111 is controlled to operate. The operating frequency of the CPU 111 can be calculated if the return time from the sleep mode and the job amount of the received print job are known. Assuming that the return time from the sleep mode is t, the job amount of the print job is J, and the function that determines the processing amount of the CPU 111 per unit time for the operating frequency ω is f (ω),
t = J / f (ω) (3)
It becomes. Therefore, the operating frequency ω that satisfies this equation may be obtained. Note that f (ω) is a function that varies depending on the CPU 111, and can be represented by, for example, f (ω) = a (proportional coefficient) · ω.

  In the above, the minimum value of the operating frequency ω is a value that can process the job amount J using the return time t as much as possible. The return time t, that is, the time required for the fixing temperature of the fixing device 171 to rise to a printable temperature is usually longer than the time required for image processing by the image processing unit 11. Therefore, the operating frequency (processing speed) of the CPU 111 can be lowered so that the image processing is completed within the return time t. By reducing the operating frequency, the power consumption of the CPU 111 is reduced, and consequently the power consumption of the image forming apparatus 10 is reduced.

  In addition, the power control unit 117 identifies a circuit unnecessary for image processing by the image processing unit 11 and controls power supply to the unnecessary circuit. For example, it is determined that a partial area of the storage unit 112 that is not used in the raster development process, the external I / F 115, the HDD 116, or the like is not necessary for image processing. Then, the power control unit 117 stops or restricts the power supply to a partial area of the storage unit 112, the external I / F 115, and the HDD 116. Thus, by stopping or restricting the power supply to unnecessary circuits, the power consumption of the image forming apparatus 10 can be further reduced.

  When an additional print job is received during image processing by the image processing unit 11, the job amount calculation unit 113 recalculates the job amounts of all print jobs received by the image processing unit 11. Then, the frequency control unit 118 recalculates the lowest operating frequency that can complete the image processing of all job amounts calculated by the job amount calculation unit 113 within the return time calculated by the return time calculation unit 12. The CPU 111 may be controlled to operate at this operating frequency.

  When an additional job is received during image processing, the necessary area of the storage unit 112 may increase and an unnecessary area may change. Therefore, in addition to resetting the operating frequency of the CPU 111, the power control unit 117 may re-specify circuits unnecessary for image processing by the image processing unit 11 and control power supply to unnecessary circuits. .

  As described above, even when an additional job is received during the return from the sleep mode, the image processing can be completed until the image forming apparatus is ready for printing by readjusting the operating frequency and the like. The printing process can be performed without delay.

  The image processing time calculation unit 114 calculates an image processing time required for image processing of the print job received by the image processing unit 11. Then, based on the image processing time calculated by the image processing time calculation unit 114, the timing for starting the image processing for the print job may be adjusted. That is, even when a print job is received and the sleep mode is canceled, power is not immediately supplied to the image processing unit 11 and the image processing start timing is delayed. The power supply to the image forming unit 17 starts immediately after the sleep mode is canceled.

  As described above, by delaying the start timing of energization of the CPU 111 included in the image processing unit 11, no power consumption occurs between the release of the sleep mode and the start of energization in the image processing unit 11. For this reason, power consumption can be reduced.

  In addition, the image processing start timing is changed step by step from the time when the image processing unit 11 receives a print job. The power consumption required for image processing is compared at each timing, and the timing at which the power consumption is lowest is determined. The image processing start timing may be determined.

Specifically, the operating frequency before the start of image processing is ω1, the time from reception of the print job to the start of image processing is t1, the operating frequency after the start of image processing is ω2, and from the start of image processing to the return to the printable state The power consumption W required at this time can be calculated from the following equation.
W = g (ω1) · t1 + g (ω2) · t2 Equation (4)
However, g (ω1) is a function representing power consumption per unit time with respect to the operating frequency ω1, and g (ω2) is a function representing power consumption per unit time with respect to the operating frequency ω2.

  From the above equation, when the time t1 is set to a certain value, the time t2 is obtained as t−t1. Furthermore, the operating frequency ω2 that minimizes g (ω2) · t2 can also be uniquely determined. Since the operating frequency ω1 is a system-specific specified value, the power consumption W can be obtained by determining the time t1. Here, by changing the time t1 stepwise from 0 to t, the total power consumption W at each timing can be obtained. The timing of time t1 when the total power consumption W is the lowest is set as the image processing start timing. As described above, the image processing start timing may be delayed so that the image processing can be completed within the return time from the sleep mode. Thereby, the power consumption of the image forming apparatus can be reduced.

  FIG. 3 is a diagram for explaining an example of the relationship between power consumption and image processing time when a print job is received in the sleep mode in the image forming apparatus 10 of the present invention. In the figure, (1) indicates that image processing is in progress. When the image forming apparatus 10 is in the sleep mode, when receiving a print job from the host computer or the like, the image forming apparatus 10 cancels the sleep mode and starts a return process to a printable state. That is, power is supplied to the image processing unit 11 and the image forming unit 17, the CPU 111 provided in the image processing unit 11 is energized, and warming up of the fixing device 171 provided in the image forming unit 17 is started. The received print job is subjected to image processing by the image processing unit 11 and developed into raster data.

  As described above, the recovery time t calculated by the recovery time calculation unit 12, that is, the time required for the fixing temperature of the fixing device 171 to rise to a printable temperature is usually required for image processing by the image processing unit 11. It will be longer than time. Therefore, the operating frequency (processing speed) of the CPU 111 can be lowered so that the image processing is completed within the return time t.

  The frequency control unit 118 calculates the lowest operating frequency at which image processing of the job amount calculated by the job amount calculating unit 113 can be completed within the return time t, and controls the CPU 111 to operate at this operating frequency. . Specifically, the operating frequency can be obtained from the above-described equation (3). The minimum value of the operating frequency is a value that can process the received job amount using the return time t as much as possible. By reducing the operating frequency, the power consumption of the CPU 111 is reduced, and consequently the power consumption of the image forming apparatus 10 is reduced.

  In the case of this example, the image processing of (1) is executed by the CPU 111 of the image processing unit 11, but the operating frequency of the CPU 111 is set lower than usual, and the warm-up time (return time t) is maximized. The process is executed using. Accordingly, the timing at which the image processing in (1) is completed substantially coincides with the timing at which warm-up is completed. Thus, by reducing the operating frequency of the CPU 111, the processing time is lengthened within the warm-up time, so that power consumption when returning from the sleep mode can be reduced.

  At this time, the power control unit 117 may specify a circuit unnecessary for image processing by the image processing unit 11 and control power supply to the unnecessary circuit. For example, it is determined that a partial area of the storage unit 112 that is not used in the raster development process, the external I / F 115, the HDD 116, or the like is not necessary for image processing. Then, the power control unit 117 stops or restricts the power supply to a partial area of the storage unit 112, the external I / F 115, and the HDD 116. Thus, by stopping or restricting the power supply to unnecessary circuits, the power consumption of the image forming apparatus 10 can be further reduced.

  FIG. 4 is a diagram for explaining another example of the relationship between power consumption and image processing time when a print job is received in the sleep mode in the image forming apparatus 10 of the present invention. In the figure, (1) indicates that image processing is in progress. In the case of this example, the image processing time calculation unit 114 calculates the image processing time required for the image processing of the print job accepted by the image processing unit 11. Based on the image processing time calculated by the image processing time calculation unit 114, the image processing start timing for starting image processing for the print job is adjusted.

  That is, even when a print job is received and the sleep mode is canceled, power is not immediately supplied to the image processing unit 11 and the image processing start timing is delayed. The power supply to the image forming unit 17 starts immediately after the sleep mode is canceled.

  As described above, by delaying the start timing of energization of the CPU 111 included in the image processing unit 11, no power consumption occurs between the release of the sleep mode and the start of energization in the image processing unit 11. For this reason, power consumption can be reduced.

  Note that the operating frequency of the CPU 111 can be adjusted within a range where the image processing can be completed within the return time t. Accordingly, the operating frequency of the CPU 111 is lowered to increase the image processing time of (1), or the operating frequency of the CPU 111 is increased to shorten the image processing time of (1), or the job amount and consumption What is necessary is just to adjust suitably from the balance of electric power.

  Further, when the time t1 from the reception of the print job to the start of the image processing is set to a certain value, the time t2 from the start of the image processing until the printing becomes possible is obtained as t−t1. Furthermore, the operating frequency at which the power consumption W2 corresponding to the time t2 after the start of image processing is minimized can be uniquely obtained. Further, since the operating frequency before the start of image processing is a system-specific prescribed value, the power consumption W1 corresponding to the time t1 can be obtained by determining the time t1 before the start of image processing.

  By changing the time t1 stepwise from 0 to t, the total power consumption W (W1 + W2) at each timing is obtained. The timing of time t1 when the total power consumption W is the lowest is set as the image processing start timing. Thus, the image processing start timing with the lowest power consumption may be determined so that the image processing can be completed within the return time t from the sleep mode. Thereby, the power consumption of the image forming apparatus can be more effectively reduced.

  FIG. 5 is a diagram for explaining another example of the relationship between power consumption and image processing time when a print job is received in the sleep mode in the image forming apparatus 10 of the present invention. In the figure, (1) indicates that image processing is in progress. In this example, when an additional print job is received during image processing by the image processing unit 11, the job amount calculation unit 113 recalculates the job amounts of all print jobs received by the image processing unit 11. Then, the frequency control unit 118 recalculates the lowest operating frequency that can complete the image processing of all job amounts calculated by the job amount calculation unit 113 within the return time calculated by the return time calculation unit 12. The CPU 111 is controlled to operate at this operating frequency.

  In the case of this example, the image processing of (1) is executed by the CPU 111 of the image processing unit 11, but the operating frequency of the CPU 111 is set lower than usual, and the warm-up time (that is, the return time t) is set. Processing is performed using the maximum amount. When an additional print job is received during this process, the job amounts of all print jobs including this additional amount are recalculated. Then, the operating frequency of the CPU 111 is set again so that all image processing including the added amount is completed within the return time t. In this case, since the amount of image processing increases, the operating frequency becomes slightly high, so that the power consumption increases.

  In this case as well, as in the example of FIGS. 3 and 4, the timing at which the image processing of (1) is completed substantially coincides with the timing at which the warm-up is completed. In this way, even when an additional job is received during the return from the sleep mode, the image processing can be completed until the image forming apparatus is ready to print by re-adjusting the operating frequency, etc. Printing processing can be performed without delay.

  FIG. 6 is a diagram for explaining another example of the relationship between power consumption and image processing time when a print job is received in the sleep mode in the image forming apparatus 10 of the present invention. In the figure, (1) indicates that image processing is in progress. In the case of this example, when it is not necessary to immediately output the print job received by the image processing unit 11, the image processing by the image processing unit 11 is performed with the minimum power consumption. The minimum necessary power consumption is, for example, when the operation frequency of the CPU 111 is set to a minimum operable value, or in addition to setting the operation frequency of the CPU 111 to the minimum value, the image processing unit 11 is unnecessary. This corresponds to the power consumption when the power supply to the circuit is stopped.

  The image processing (1) is executed by the CPU 111 of the image processing unit 11, and the operating frequency of the CPU 111 is set to a minimum value that can be operated according to the minimum necessary power consumption. For this reason, although processing time is required, it becomes possible to keep power consumption low. Note that whether or not the print job received by the image processing unit 11 is not in a hurry may be determined in advance using a flag indicating that the print job is not in a hurry in advance. As described above, in the case of a print job that does not need to be printed in a hurry, image processing is performed with the minimum necessary power consumption. However, although processing time is required, power consumption can be significantly reduced.

  Note that image processing performed with the minimum necessary power consumption cannot always be completed within the return time t. Therefore, the image processing time (1) may be longer than the return time t. In this case, printing cannot be performed until the image processing of (1) is completed, even though the printer is warmed up at the return time t and is ready for printing. Accordingly, there is a waiting time of the image forming unit 17 from the printable point in time of the return time t to the end point of the image processing in (1), and the fixing device 171 must be kept warm during this waiting time. , Wasteful power consumption.

  Therefore, when the image processing time (1) required for the image processing performed with the minimum necessary power consumption is longer than the return time t, the timing for starting the heating to the fixing device 171 is determined from immediately after the sleep mode is released. It may be shifted by time t3. The predetermined time t3 is preferably substantially the same as the time from the printable timing of the return time t to the completion timing of the image processing (1).

  Thus, by delaying the heating start (energization start) timing of the fixing device 171 by the predetermined time t3, the return time t is shifted by the predetermined time t3 to become the return time t ′. Accordingly, since the completion timing of the return time t ′ and the completion timing of the image processing time (1) substantially coincide with each other, the waiting time of the image forming unit 17 does not occur, and the power consumption of this waiting time is reduced. Can do.

FIG. 7 is a flowchart for explaining an example of the relationship between power consumption and image processing time when a print job is received in the sleep mode in the image forming apparatus 10 of the present invention. This example will be described based on the example shown in FIG.
7A, first, when receiving a print job in the sleep mode, the image forming apparatus 10 starts supplying power to the image processing unit 11 and the image forming unit 17, and the fixing temperature of the fixing device 171 at this time is started. Is measured (step S1), and a return time t from the measured fixing temperature until the fixing temperature at which printing is possible is calculated (step S2).

  Next, the image forming apparatus 10 controls the image processing start timing by the image processing unit 11 (step S3), and controls the operating frequency of the CPU 111 (step S4). Then, power supply to circuits unnecessary for image processing is stopped or restricted (step S5).

  Next, the image forming apparatus 10 executes image processing in the image processing unit 11 (step S6), and determines whether the image forming unit 17 has been warmed up and is ready for printing (step S7). If printing is possible (YES), printing processing is executed by the image forming unit 17 (step S8). If it is not in a printable state (NO), the process is repeated in step S7.

  FIG. 7B is a flowchart for explaining a detailed example of image processing start timing control in step S3 shown in FIG. First, the image forming apparatus 10 calculates power consumption when t1 = 0 and t2 = t (step S11), and calculates power consumption when the ratio of t1 is increased (step S12). Then, t1 and t2 at which the power consumption is minimized, the operating frequency of the CPU 111 at that time, a circuit for stopping the power supply in the image processing unit 11, and the like are determined (step S13).

  Although the embodiments of the image forming apparatus 10 have been described so far, the present invention may be configured as an image forming system including the external information processing apparatus 1. That is, the external information processing apparatus 1 includes a job amount calculation unit 113 that calculates the job amount of a print job to be transmitted to the image forming apparatus 10, and the image forming apparatus 10 receives a print job and its job amount from the external information processing apparatus 1. , An image processing unit 11 that performs image processing on a print job and develops it into printable raster data, and a return until the image forming apparatus 10 returns from a power saving state to a printable state A recovery time calculation unit 12 that calculates time and a frequency control unit 118 that controls the operating frequency of the CPU 111 included in the image processing unit 11 are provided. Then, the frequency control unit 118 calculates the lowest operating frequency that can complete the image processing of the job amount within the return time, and controls the CPU 111 to operate at the operating frequency.

  The return time calculation unit 12 may be provided in the external information processing apparatus 1. In this case, when the external information processing apparatus 1 transmits a print job to the image forming apparatus 10 in the sleep mode, the image forming apparatus 10 measures the fixing temperature of the fixing apparatus 171 by the fixing temperature measuring unit 13. Then, the external information processing apparatus 1 acquires the fixing temperature in the sleep mode from the image forming apparatus 10. Then, a time from the fixing temperature in the sleep mode acquired from the image forming apparatus 10 to the fixing temperature at which the image forming apparatus 10 can perform printing is calculated as a return time t. The fixing temperature at which the image forming apparatus 10 can print may be stored in advance in the internal memory of the external information processing apparatus 1 or the like.

  In addition, the external information processing apparatus 1 includes an image processing time calculation unit 114 that calculates an image processing time required for image processing of a print job to be transmitted to the image forming apparatus 10, and the image forming apparatus 10 includes the image processing time calculation unit 114. The image processing start timing for starting the image processing for the print job may be adjusted based on the image processing time calculated in (1).

  In this way, by causing the external information processing apparatus to perform a part of the arithmetic processing of the image forming apparatus, the load is distributed to the external information processing apparatus, the processing load of the image forming apparatus is reduced, and the processing time in the image forming apparatus is reduced. Can be shortened and power consumption can be reduced.

  As described above, according to the present invention, when a print job is received in the power saving state, image processing can be performed with the CPU operating frequency lowered within the return time until the printable state is obtained. Therefore, power consumption when returning from the power saving state can be reduced.

1 is a block diagram illustrating a configuration example of an image forming system according to an embodiment of the present invention. It is a block diagram which shows the structural example of the image process part shown in FIG. FIG. 6 is a diagram for explaining an example of a relationship between power consumption and image processing time when a print job is received in a sleep mode in the image forming apparatus of the present invention. FIG. 10 is a diagram for explaining another example of the relationship between power consumption and image processing time when a print job is received in the sleep mode in the image forming apparatus of the present invention. FIG. 10 is a diagram for explaining another example of the relationship between power consumption and image processing time when a print job is received in the sleep mode in the image forming apparatus of the present invention. FIG. 10 is a diagram for explaining another example of the relationship between power consumption and image processing time when a print job is received in the sleep mode in the image forming apparatus of the present invention. 6 is a flowchart for explaining an example of a relationship between power consumption and image processing time when a print job is received in a sleep mode in the image forming apparatus of the present invention. FIG. FIG. 10 is a diagram for explaining a relationship between power consumption and image processing time when a print job is received in a sleep mode in a conventional image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... External information processing apparatus, 10 ... Image forming apparatus, 11 ... Image processing part, 12 ... Return time calculation part, 13 ... Fixing temperature measurement part, 14 ... Operation information input part, 15 ... Information display part, 16 ... Image reading , 17 ... Image forming unit, 18 ... Main control unit, 111 ... CPU, 112 ... Storage unit, 113 ... Job amount calculation unit, 114 ... Image processing time calculation unit, 115 ... External I / F, 116 ... HDD, 117 ... Power control unit, 118 ... Frequency control unit, 171 ... Fixing device.

Claims (11)

An image forming apparatus that includes an image processing unit that performs image processing on a print job and develops the raster data into printable raster data, and performs image formation based on the raster data that has been developed.
A return time calculation unit that calculates a return time until the image forming apparatus returns from a power saving state to a printable state, and calculates a job amount of a print job accepted by the image processing unit when the image forming apparatus is in a power saving state. A job amount calculation unit, and a frequency control unit that controls an operating frequency of a CPU included in the image processing unit,
The frequency control unit calculates the lowest operating frequency at which image processing for the job amount can be completed within the return time, and controls the CPU to operate at the operating frequency. .   The image forming apparatus according to claim 1, wherein the return time calculating unit calculates a time from when the image forming apparatus receives a print job in a power saving state to when the image forming apparatus rises to a printable fixing temperature. An image forming apparatus that calculates the return time.   The image forming apparatus according to claim 1, further comprising: a power control unit that identifies a circuit that is unnecessary for image processing by the image processing unit and stops or restricts power supply to the identified unnecessary circuit. An image forming apparatus. The image forming apparatus according to claim 1, wherein an additional print job is received during image processing by the image processing unit.
The job amount calculation unit recalculates the job amounts of all print jobs received by the image processing unit,
The frequency control unit recalculates the lowest operating frequency that can complete image processing of all the job amounts within the return time, and controls the CPU to operate at the operating frequency. Image forming apparatus. 5. The image forming apparatus according to claim 1, further comprising an image processing time calculation unit that calculates an image processing time required for image processing of a print job received by the image processing unit.
An image forming apparatus, wherein an image processing start timing for starting image processing for the print job is adjusted based on the image processing time calculated by the image processing time calculation unit.   6. The image forming apparatus according to claim 5, wherein the image processing start timing is changed stepwise from the time when a print job is received by the image processing unit, and the power consumption required for image processing is compared at each timing. An image forming apparatus characterized in that a timing at which power consumption is lowest is determined as the image processing start timing.   5. The image forming apparatus according to claim 1, wherein when the print job received by the image processing unit does not need to be output immediately, the image processing by the image processing unit is performed with a minimum consumption. An image forming apparatus characterized by being performed with electric power. 8. The image forming apparatus according to claim 7, further comprising a fixing device heated to a predetermined fixing temperature,
When the time required for image processing performed with the minimum necessary power consumption is longer than the return time, the timing for starting heating the fixing device is shifted by a predetermined time immediately after the power-saving state is released. An image forming apparatus.   9. The image forming apparatus according to claim 1, wherein the power saving state is a sleep mode in which power consumption of the image forming apparatus is a predetermined value or less. . An image forming system comprising: an information processing apparatus that transmits a print job; and an image forming apparatus that forms an image based on the print job from the information processing apparatus,
The information processing apparatus includes a job amount calculation unit that calculates a job amount of a print job to be transmitted to the image forming apparatus.
The image forming apparatus includes a receiving unit that receives a print job and a job amount from the information processing apparatus, an image processing unit that performs image processing on the print job and develops it into printable raster data, and the image forming apparatus. A return time calculation unit that calculates a return time until the printer returns from the power saving state to the printable state, and a frequency control unit that controls the operating frequency of the CPU provided in the image processing unit,
The frequency control unit calculates the lowest operating frequency at which image processing for the job amount can be completed within the return time, and controls the CPU to operate at the operating frequency. . The image forming system according to claim 10, wherein the information processing apparatus includes an image processing time calculation unit that calculates an image processing time required for image processing of a print job transmitted to the image forming apparatus,
The image forming apparatus adjusts an image processing start timing for starting image processing for the print job based on the image processing time calculated by the image processing time calculation unit.

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