JP2013118630A - Image forming apparatus and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new image forming apparatus and a control method thereof capable of maximizing a power-saving effect without sacrificing isochronism of data transfer.SOLUTION: The present invention provide an image forming apparatus which comprises in an image processing part plural PCI Express devices. Each of the PCI Express devices includes a line utilization rate measurement section which measures a line utilization rate in data transfer; and an ASPM use propriety determination section which controls the ASPM to be enabled only when the line utilization rate is smaller than a predetermined line utilization rate threshold.

Description

  The present invention relates to an image forming apparatus and a control method thereof.

  In an image forming apparatus such as a digital multi-function peripheral (MFP) that requires high-speed and high-quality image formation, it is necessary to transfer a large amount of data within a certain period between devices involved in image processing. If this is not possible, an abnormal image will be generated.

  In view of this point, it has been studied to secure a sufficient transfer rate by adopting PCI Express (registered trademark) as a connection means between devices. PCI Express (hereinafter referred to as PCIe) is a high-speed serial interface standard defined by PCISIG (Peripheral Component Interconnect Special Interest Group), and interconnects devices via a communication path called “link”.

  Here, in the PCIe standard, ASPM (Active State Power Management) is defined as a standard for power management. According to ASPM, the PCIe device detects that the idle state of the link connecting the devices has continued for a certain period of time on the hardware and transitions to the power saving state, so that unnecessary power is consumed during the idle period of the link. Suppressing consumption.

  However, recovery from the power saving state to the normal state requires a recovery time of about several μsec. Therefore, if ASPM control is enabled in a link that requires isochronous, the isochronous data transfer is lost due to the return time, and an abnormal image may be generated.

  In this regard, Japanese Patent Application Laid-Open No. 2009-176294 (Patent Document 1) discloses that the scanner data is reliably disabled by disabling the ASPM control in response to the user instructing the scanner reading from the operation unit. Disclosed is an image processing apparatus to be transferred to

  According to the method of Patent Document 1, the isochronism of the transfer data is surely ensured. However, in the method of Patent Document 1, in the use case where the ratio of the data transfer period to the lsync cycle is small, there is a problem that wasteful power is still consumed in the non-data transfer period.

  The present invention has been made in view of the above-described problems in the prior art, and the present invention is a novel image forming apparatus capable of maximizing the power saving effect without sacrificing isochronism of data transfer. And it aims at providing the control method.

  As a result of earnestly examining the novel image forming apparatus and its control method capable of maximizing the power saving effect without sacrificing isochronism of data transfer, the inventors have conceived the following configuration, The present invention has been reached.

  That is, according to the present invention, an image forming apparatus including a plurality of devices connected by a serial bus in an image processing unit, the device measuring line utilization rate for measuring a line utilization rate during data transfer. And an ASPM availability determination unit that enables ASPM to be enabled only when the line usage rate is smaller than a predetermined line usage rate threshold.

  According to the present invention, there is provided an image forming apparatus including a plurality of devices connected by a serial bus in an image processing unit, wherein the device measures a line utilization rate for measuring a line utilization rate during data transfer. And an ASPM availability determination unit that controls whether or not ASPM can be used. The ASPM availability determination unit is a period in which scanner data transfer and printer data transfer are executed simultaneously or only for full-color printer data transfer. In the period in which ASPM is disabled, the ASPM is controlled to be disabled, and in the period in which only the scanner data transfer from the upstream device is performed, the ASPM is controlled following the ASPM control content in the upstream device, In a period in which only monochrome or two-color printer data transfer is executed, the line utilization rate is a predetermined label. Image forming apparatus for controlling the enable is provided a ASPM only if less than emissions utilization threshold.

FIG. 3 is a functional block diagram of an image processing unit of the image forming apparatus according to the embodiment. The conceptual diagram for demonstrating the idle period which generate | occur | produces within a lsync period. The functional block diagram of the PCIe Root module in this embodiment. The figure which shows the ASPM control part in this embodiment. The flowchart which shows the initial setting process of ASPM in this embodiment. The conceptual diagram for demonstrating the line utilization rate threshold value in this embodiment. The flowchart which shows the ON / OFF control process of ASPM which the ASPM control part in this embodiment performs. The sequence diagram when the ON / OFF control of ASPM is executed. The functional block diagram of ASIC in this embodiment. FIG. 4 is a diagram illustrating a printer data transfer sequence in a full color printing mode. The functional block diagram of the PCIe Root module in this embodiment. The figure which shows the ASPM control part in this embodiment. The conceptual diagram for demonstrating the line utilization rate threshold value in this embodiment. The flowchart which shows the ON / OFF control process of ASPM which the ASPM control part in this embodiment performs.

  Hereinafter, although this invention is demonstrated with embodiment, this invention is not limited to embodiment mentioned later. In the drawings referred to below, the same reference numerals are used for common elements, and the description thereof is omitted as appropriate.

  FIG. 1 is a functional block diagram of an image processing engine (IPU board 10) and a controller (CTL board 20) constituting an image processing unit of an image forming apparatus according to an embodiment of the present invention.

  The IPU board 10 includes an ASIC 1 (11) for executing image processing of scanner data received from the scanner 15, an ASIC 2 (12) as a bus bridge for interfacing the IPU board 10 and the CTL board 20, and the IPU board 10. CPU 1 (13) for controlling the image data, and write processing ASIC 4 (14) for writing processed image data to the plotter 16.

  On the other hand, the CTL board 20 includes an ASIC 3 (21) as a chip set that interfaces with the IPU board 10 and has an interface with the memory 23, and a CPU 2 (22) that controls the CTL board 20. The

  ASIC1 to ASIC3 shown in FIG. 1 are all PCI Express devices (hereinafter referred to as PCIe devices) conforming to the PCI Express standard, and between ASIC1 (11) and ASIC2 (12) and ASIC2 (12 ) And ASIC3 (21) are connected via a high-speed serial interface (high-speed serial bus) defined by PCI Express, respectively.

  Here, ASIC1 (11), ASIC2 (12), and ASIC3 (21) mount an ASPM (Active State Power Management) control unit as a PCIe device. Here, ASPM means a power management function related to power saving of PCIe (high-speed serial bus) that connects devices, and an ASPM (Active State Power Management) control unit keeps the PCIe link in an idle state for a certain period or more. Then, it is configured to automatically transition from the normal state (L0) to the power saving state (L0s / L1) to suppress wasteful power consumption.

  In general, the lsync period of the image forming apparatus is set so as to satisfy the assumed maximum bandwidth. For example, when the image forming apparatus is a model that supports 400% enlargement / reduction, as shown in FIG. 2A, a period required to transfer data for four lines is set as an lsync cycle. Therefore, in the image forming apparatus, when data of 100% magnification is transferred, as shown in FIG. 2B, the ratio (line usage rate) occupied by the data transfer period in the lsync cycle is 25%. The remaining 75% period is idle. Therefore, in order to maximize the power saving effect of the image forming apparatus, it is necessary to shift each device to the power saving state (L0s / L1) during the idle period.

  However, in general, a PCIe device requires a recovery time of about several μs to several tens of μs to return from the power saving state (L0s / L1) to the normal state. Therefore, if ASPM is enabled unconditionally, data There is a possibility that the image will not be returned in time for the transfer request, resulting in an abnormal image. With respect to this point, the image forming apparatus according to the present embodiment employs the following configuration, thereby enabling the PCIe device to transition to the power saving state within a range that does not affect the isochronism of data transfer. . Hereinafter, this point will be described in order.

  FIG. 3 shows functional blocks of the root module 30 of the ASIC 2 (12) shown in FIG. As shown in FIG. 3, the Root module 30 is a PCIE logic layer circuit 31 that is a control circuit for realizing a PCIE logic layer, and data for transferring data for one line received from the PCIE logic layer circuit 31 in a 1 lsync cycle. The transfer control unit 33 is included.

  In the Config register control unit 32 included in the PCIE logic layer circuit 31, the time required for returning from the power saving state (L0s / L1) is held in the L0s / L1 Exit Latency of the Link Capabilities Register as a device-specific value. .

  The data transfer control unit 33 includes an lsync signal generation unit 34 for synchronizing the internal transfer of the ASIC with lsync, a main scanning counter 35 that operates for each line data and counts a predetermined main scanning size, and various parameters. The register control unit 36 that holds the data and the ASPM control unit 40 are configured. Here, the ASPM control unit 40 is configured to be able to access both the Config register control unit 32 of the PCIE logic layer circuit 31 and the Config register control unit (not shown) of the End Point module 38 of the ASIC 1 (11).

  FIG. 4 shows only the ASPM control unit 40 in an enlarged manner. The ASPM control unit 40 includes an ASPM availability determination unit 42 and a line usage rate measurement unit 44, and the line usage rate measurement unit 44 further includes a data transfer period counter 46.

  On the other hand, the ASPM availability determination unit 42 includes a line usage rate threshold value setting unit 43 for setting a line usage rate threshold value that is a determination criterion for ASPM availability. Hereinafter, the procedure in which the line usage rate threshold setting unit 43 sets the line usage rate threshold will be described in order.

  In the image forming apparatus of the present embodiment, the ASPM initial setting process is executed prior to setting the line usage rate threshold, and the return time used for calculating the line usage rate threshold is determined in the initial setting process. Is done. Hereinafter, the initial setting process of ASPM including the determination process of the return time will be described based on the flowchart shown in FIG.

  In step 101, the configuration setting of the Root module 30 of the ASIC2 (12) is performed, and in step 102, the configuration setting of the End Point module 38 of the ASIC1 (11) is performed.

  Subsequently, in Step 103, the Link Capabilities Register of the Config register control unit 32 of the Root module 30 of the ASIC 2 (12) is read, and the values of the bits of “ASPM Support”, “L0s Exit Latency”, and “L1 Exit Latency” are set. It is held (step 104).

  Further, in Step 105, the Link Capabilities Register of the Config register (not shown) of the End Point module 38 of the ASIC 1 (11) is read, and the values of the bits of “ASPM Support”, “L0s Exit Latency” and “L1 Exit Latency” are held. (Step 106).

  Next, in step 107, it is determined whether the Root module 30 and the End Point module 38 support L0s or L1. The power saving state of ASPM changes to the power saving state of L0s if at least one of the connected devices only supports L0s. If both of the connected devices support L1, L1 Transition to the power saving state.

  If both the Root module 30 and the End Point module 38 support both L0s and L1 (Step 107, Yes), the process proceeds to Step 112, where the respective links of the Root module 30 and the End Point module 38 are linked. The ASPM Control value of the Control Register is set to [0x11], and ASPM is set to “L0s and L1 Entry Enabled”. In step 113, the “L1 Exit Latency” value of the Root module 30 held in step 104 is compared with the “L1 Exit Latency” value of the End Point module 38 held in step 106. As a result, the larger value is determined as the return time used for the calculation of the line usage rate threshold value, and the process is terminated.

  On the other hand, if it is determined in step 107 that the root module 30 and the end point module 38 do not support both L0s and L1 (step 107, No), the process proceeds to step 108, where the root module 30 and the end point It is determined whether the module 38 supports L0s. As a result, if L0s is supported (step 108, Yes), the process proceeds to step 110, and the value of ASPM Control in each Link Control Register of the Root module 30 and End Point module 38 is set to [0x01]. , ASPM is set to “L0s Entry Enabled”, and the process proceeds to step 111. In step 111, the “L0s Exit Latency” value of the Root module 30 held in step 104 is compared with the “L0s Exit Latency” value of the End Point module 38 held in step 106. As a result, the larger value is determined as the return time used for the calculation of the line usage rate threshold value, and the process is terminated.

  On the other hand, if both the Root module 30 and the End Point module 38 do not support L0s (No at Step 108), the process proceeds to Step 109, and the ASPM of each Link Control Register of the Root module 30 and the End Point module 38 is reached. The value of Control is set to [0x00], ASPM is set to “Disabled”, and the process ends.

  The line usage rate threshold setting unit 43 defines the line usage rate threshold based on the return time determined by the above-described procedure and the time until the transition to the power saving state is started. Hereinafter, the concept of the line utilization rate threshold defined in the present embodiment will be described with reference to FIG.

FIG. 6 shows a sequence at the time of scanner data transfer. Note that “LTSSM” in FIG. 6 indicates a PCIe link state, and the content is as follows.
L0: Normal state
L0s: Power saving state by ASPM (shallow)
L1: Power saving state by ASPM (slightly deep)
Rcv: State to prepare for recovery when recovering from L1 to L0 (recovery state)

6A shows the power saving state of L0s, FIG. 6B shows the power saving state of L1, and in each figure, T1 to T4 mean the following.
T1: Return time from the energy saving state T2: Data transfer time T3: Time until the transition to the energy saving state is started T4: lsync cycle

  As shown in FIGS. 6A and 6B, the non-data transfer period (T4-T2) in the lsync cycle is the return time from the energy saving state (T1: hereinafter referred to as the return time) and the energy saving state. Is greater than the total time (T1 + T3) until the transition to (T3: hereinafter referred to as transition preparation time) is started, a non-data transfer period (hereinafter referred to as power saving target) It will be understood that there exists (referred to as an energy saving period). On the other hand, if (T4−T2) is not larger than (T1 + T3), even if there is a non-data transfer period within the lsync period, all of it is spent on the return time and transition preparation time. Therefore, the non-data transfer period cannot be a power saving target, and there is no room for using ASPM.

  Here, the case where (T4−T2) is larger than (T1 + T3), that is, the case where the line utilization rate [T2 / lsync period] is smaller than [1- (T1 + T3) / lsync period] Can be replaced. Focusing on this point, in the present embodiment, a line utilization rate threshold is defined by the following equation (1) as an index for determining whether or not ASPM can be applied.

  The line usage rate threshold value setting unit 43 calculates and holds the line usage rate threshold value by introducing the return time and the transition preparation time determined in the initial setting process of ASPM shown in FIG. 5 into the above equation (1). The procedure for setting the line usage rate threshold by the line usage rate threshold setting unit 43 in the present embodiment has been described above. Next, the ASPM control unit 40 executes the ASPM based on the set line usage rate threshold. The ON / OFF control process will be described based on the flowchart shown in FIG.

  When the ASIC 1 (11) and the ASIC 2 (12) are activated by the CPU 1 shown in FIG. 1 when reading the scanner, the ASPM control unit of each device responds to the assertion of the activation flag (step 201, Yes), and performs ASPM. It is disabled (OFF) (step 202).

  Subsequently, when the scanner data is transferred from the scanner 15, in step 203, the line usage rate measuring unit 44 measures the line usage rate of the first line in the following procedure. First, the data transfer period counter 46 of the line utilization rate measuring unit 44 sets the period from the start to the end of the operation of the main scanning counter 35 that operates for each line data (that is, the time required for counting the main scanning size) as the data transfer period. Measure as The data transfer period counter 46 is reset when lsync is asserted. The line utilization rate measuring unit 44 calculates the line utilization rate by the following equation (2) based on the data transfer period measured by the data transfer period counter 46 and the lsync cycle acquired from the register control unit 36 shown in FIG. The line usage rate is output to the ASPM availability determination unit 42.

  In subsequent step 204, the ASPM availability determination unit 42 compares the line usage rate input from the line usage rate measurement unit 44 with the line usage rate threshold value held in the line usage rate threshold setting unit 43. As a result, when it is determined that the line usage rate is smaller than the line usage rate threshold (step 204, Yes), the process proceeds to step 205. In step 205, the ASPM availability determination unit 42 accesses the Config register control unit 32 and enables (ON) ASPM via the ASPM Control bit of the Link Control Register. Thereafter, the process waits for completion of the job being executed (No at Step 206), and when the activation flag is negated (Yes at Step 206), the process ends.

  On the other hand, if the ASPM availability determination unit 42 determines that the line usage rate is not smaller than the line usage rate threshold (No in step 204), it waits for completion of the job being executed (No in step 207). When the activation flag is negated (Yes in Step 207), the ASPM availability determination unit 42 proceeds to Step 208, accesses the Config register control unit 32, and enables ASPM via the ASPM Control bit of the Link Control Register. After setting to (ON), the process is terminated.

  FIG. 8 shows a sequence when the ON / OFF control of ASPM shown in FIG. 7 is executed at the time of transferring the scanner data. In FIG. 8, “Lu” indicates a measured value of the line usage rate, and “Th” indicates a line usage rate threshold value.

  First, considering FIG. 8 (a), first, in response to the activation of ASIC1 and ASIC2, after the ASPM is controlled from ON to OFF, the line utilization rate of one line data is determined in the next lsync cycle. It is measured. In the case of the example shown in FIG. 8A, the measured value (Lu) of the line utilization rate is smaller than the line utilization rate threshold value (Th), so that the ASPM is turned ON from OFF in synchronization with the next lsync signal assertion. Can be switched to. As a result, the PCIe link connecting ASIC1 and ASIC2 appropriately transitions to the power saving state during the non-data transfer period that occurs within the lsync cycle.

  Next, considering FIG. 8B, similarly, in response to the activation of ASIC1 and ASIC2, after the ASPM is controlled from ON to OFF, the line utilization rate of one line data in the next lsync cycle Is measured. In the case of the example shown in FIG. 8B, the measured value (Lu) of the line utilization rate is not smaller than the line utilization rate threshold value (Th). Therefore, the ASPM OFF state is maintained as it is, and the transfer of the scanner data is completed. Wait for it to switch from OFF to ON.

  As described above, the ASPM control executed on the ASIC 2 (12) side when the scanner data is transferred from the ASIC 1 (11) to the ASIC 2 (12) has been described. Subsequently, the ASIC 3 (21) and the ASIC 2 (12). The ASPM control executed on the ASIC 3 (21) side when data is transferred between will be described.

  First, the internal configuration of the ASIC 3 (21) will be described with reference to FIG. The ASIC 3 (21) has a scanner data transfer path, a printer data transfer path, and a data transfer path from the CPU. In the ASIC 3 (21), the scanner data is written to the memory 23 (Write) and the printer data is read from the memory 23 (Read) via the memory controller 58. Requests relating to scanner data transfer and printer data transfer are arbitrated by the arbiter 57.

  Here, the ASIC 3 (21) has four printer data transfer modules 56 (referred to as VOUT modules in FIG. 9) corresponding to the respective colors of CMYK. When the printer data for one line is read from 23, the CPU 1 (13) is notified via the ASIC 2 (12). Upon receiving this notification, the CPU 1 (13) issues a request for printer data to the ASIC 3 (21) via the ASIC 2 (12). In response to this request, the printer data transfer module 56 transfers the printer data read from the memory 23 to the ASIC 2 (12).

  FIG. 10 shows a printer data transfer sequence in the full-color printing mode. In the full color printing mode, all of the four types of printer data (CMYK) are transferred in synchronization with the lsync_n signal, but the timing of the lsync_n signal of each color is shifted by the pitch between the fixing drums. Therefore, no energy saving period can occur within the lsync cycle.

  Further, since the amount of data to be transferred increases during the period in which the scanner data transfer from the ASIC 2 (12) to the ASIC 3 (21) and the printer data transfer from the ASIC 3 (21) to the ASIC 2 (12) overlap, similarly, the lsync cycle There can be no energy saving period.

  On the other hand, when only one type of printer data (K) is transferred as in the monochrome printing mode, it can be considered equivalent to the case of the scanner data transfer described above, so the energy saving period within the lsync cycle In the two-color printing mode in which only two types of printer data are transferred, an energy saving period may occur within the lsync cycle in some cases.

  In view of the above points, in this embodiment, four periods are defined based on the state of data transfer between the ASIC 3 (21) and the ASIC 2 (12), and ASPM control corresponding to each period is executed. Table 1 below summarizes the four periods based on the data transfer status and the contents of ASPM control.

  First, in the period (period 1) in which scanner data transfer and printer data transfer are executed simultaneously between ASIC2 (12) and ASIC3 (21), it is estimated that there is no energy saving period, and ASPM is disabled ( Control to OFF).

  Next, in the period (period 2) in which only the scanner data transfer from the ASIC 2 (12) to the ASIC 3 (21) is executed (period 2), the result determined by the ASPM availability determination unit 42 of the ASIC 2 (12) is followed. That is, the ON / OFF of the ASPM between the ASIC 2 (12) and the ASIC 3 (21) is controlled according to the determination result of the availability of the ASPM in the ASIC 2 (12).

  Next, in the period (period 3) in which only full-color printer data transfer from the ASIC 3 (21) to the ASIC 2 (12) is executed, it is estimated that there is no energy saving period, and the ASPM is controlled to be disabled (OFF). .

  Finally, in the period (period 4) in which only monochrome or two-color printer data transfer from the ASIC 3 (21) to the ASIC 2 (12) is executed, an energy saving period may occur. Based on the result, a determination is made as to whether or not the ASPM can be used based on the line utilization rate, and ON / OFF of the ASPM between the ASIC2 (12) and the ASIC3 (21) is controlled.

  Subsequently, a specific configuration for realizing the above-described ASPM control will be described.

  FIG. 11 shows functional blocks of the PCIe Root module 50 of the ASIC 3 (21) shown in FIG. As shown in FIG. 11, the PCIe Root module 50 includes a PCIE logic layer circuit 51 that is a control circuit for realizing a PCIE logic layer, and a data transfer control unit that transfers data transferred from the PCIE logic layer circuit 51 to the subsequent stage. 53, a register control unit 54 that holds various parameters, a main scanning counter 55 that counts the transfer main scanning size of each color of CMYK, and an ASPM control unit 60.

  In the Config register control unit 52 included in the PCIE logic layer circuit 51, the time required for returning from the power saving state (L0s / L1) is held in the L0s / L1 Exit Latency of the Link Capabilities Register as a device-specific value. .

  The data transfer control unit 53 has functions such as interface conversion and asynchronous absorption. When the data transfer control unit 53 detects that the scanner data is transferred from the ASIC 2 (12) to the ASIC 3 (21) from the communication information of the CPU 1 (13) and the CPU 2 (22), in response to this, the scanner data transfer is performed. The flag is asserted and the ASPM control unit 60 is notified accordingly.

  In addition, when the ASIC 2 (12) detects that the ASPM is usable, the data transfer control unit 53 asserts the scanner data ASPM enable flag in response to this and notifies the ASPM control unit 60 to that effect. To do. In this embodiment, when the ASIC 2 (12) determines that the ASPM can be used, the ASIC 2 (12) to the ASIC 3 (21) has a special packet indicating the same (MSI equivalent in PCI-Express). And the data transfer control unit 53 asserts the scanner data ASPM enable flag in response to detection of the packet.

  On the other hand, when the printer data transfer request is made, when the CPU 2 (22) activates the ASIC 3 (21), the printer data transfer activation flag is asserted to notify the ASPM control unit 60 of the number of channels to be activated.

  FIG. 12 shows only the ASPM control unit 60 in an enlarged manner. The ASPM control unit 60 includes an ASPM availability determination unit 62 and a line usage rate measurement unit 64. The ASPM availability determination unit 62 further includes a line usage rate threshold setting unit 63, and the line usage rate measurement unit 64 further includes a data transfer period counter 66.

  Here, the ASPM availability determination unit 62 determines whether or not the ASPM can be used based on the states of the above-described three types of flags (scanner data transfer flag, scanner data ASPM enable flag, and printer data transfer activation flag). Control ON / OFF of.

  Specifically, during the period in which both the printer data transfer start flag and the printer data transfer start flag are asserted (corresponding to period 1 in Table 1 above), the ASPM availability determination unit 62 determines that the ASPM is not used. Then, disable ASPM (OFF).

  Further, during the period when the printer data transfer activation flag is not asserted and only the scanner data transfer flag and the scanner data ASPM enable flag are asserted (corresponding to period 2 in Table 1 above), the ASPM availability determination unit 62 Determines that the ASPM can be used, and enables (turns on) the ASPM in the ASIC 3 (21).

  Further, during the period in which all the printer data transfer activation flags relating to the four color channels are asserted (corresponding to period 3 in Table 1 above), the ASPM availability determination unit 62 determines that the ASPM is unusable, and the ASPM Is disabled (OFF).

  On the other hand, during the period in which the scanner data transfer flag is not asserted and only the printer data transfer activation flag for one or two color channels is asserted (corresponding to period 4 in Table 1 above), ASPM The availability determination unit 62 determines whether or not the ASPM can be used based on the line usage rate measured by the line usage rate measurement unit 64, and controls ON / OFF of the ASPM based on the result.

  Here, the procedure in which the line usage rate threshold setting unit 63 sets a line usage rate threshold value that is a criterion for determining whether or not ASPM can be used will be described in order.

  The line usage rate threshold setting unit 63 first determines the return time and the transition preparation time in the same procedure as described in FIG. 5, and defines the line usage rate threshold based on both. Hereinafter, the concept of the line utilization rate threshold defined in the present embodiment will be described with reference to FIG.

  FIG. 13 shows a sequence when transferring printer data in the two-color printing mode (CM). In FIG. 13, “LTSSM”, “L0”, “L1”, “Rcv”, “T1”, “T2”, “T3”, and “T4” are the same as those described with reference to FIG. On the other hand, “T5” in FIG. 13 indicates a time corresponding to a shift in lsync cycle for each plate. “T5” can be obtained as a remainder when the pitch between the drums is divided by the lsync period.

  In the two-color printing mode shown in FIG. 13, the energy is saved as the difference between the non-data transfer period (T4-T2) within the lsync cycle and the sum (T1 + T3) of the return time (T1) and the transition preparation time (T3). It will be appreciated that possible periods may occur.

  Here, the presence / absence of the energy saving period (that is, whether or not ASPM can be applied) can be determined based on whether or not the line utilization rate is greater than a predetermined threshold, as described above with reference to FIG. Here, in the present embodiment, a line utilization rate threshold value at the time of printer data transfer is defined by the following equation (3).

(In the above formula (3), (inter-drum pitch% lsync cycle) represents a time corresponding to the remainder when the inter-drum pitch is divided by the lsync cycle.)

  In the above formula (3), the reason why (T5: pitch between drums% lsync cycle) is subtracted from the lsync cycle is that there is a case where the pitch between drums is equal to or larger than the lsync cycle.

  The line usage rate threshold value setting unit 63 calculates and holds the line usage rate threshold value by introducing the return time and transition preparation time determined in the initial setting process of ASPM into the above equation (3).

  The procedure for setting the line usage rate threshold by the line usage rate threshold setting unit 43 in the present embodiment has been described above. Next, the ASPM control unit 60 executes the ASPM based on the set line usage rate threshold. The ON / OFF control process will be described based on the flowchart shown in FIG.

  When the printer data transfer is requested, the CPU 2 (22) shown in FIG. 1 activates the ASIC 3 (21). At this time, the CPU 2 (22) asserts the printer data transfer activation flag of the channel to be activated.

  In response to the assertion of the printer data transfer activation flag (step 301, Yes), the ASPM control unit 60 disables (OFF) the ASPMs of the ASIC2 (12) and the ASIC3 (21) (step 302). .

  In the subsequent step 303, the ASPM control unit 60 determines whether the number of activated channels is 2 or less based on the asserted flag (step 303). As a result, when it is determined that the number of activated channels is not 2 or less (No in Step 303), the process proceeds to Step 311 to wait for completion of the job being executed (No in Step 311), and the activation flag is set. If negated (Yes at step 311), ASPM is enabled (ON) and the process is terminated.

  On the other hand, if another channel is activated (step 313, Yes) while the job being executed is not completed (step 311: No), the process returns to step 302.

  On the other hand, when it is determined in step 303 that the number of activated channels is 2 or less (step 303, Yes), the process proceeds to step 304, and it is determined whether or not the number of activated channels is 1.

  As a result, when it is determined that the number of channels is 1 (Yes in Step 304), the process proceeds to Step 305, and the line usage rate measurement unit 64 measures the line usage rate of the first line for the transfer data for one color. On the other hand, if it is determined that the number of channels is not 1 (step 304, No), the process proceeds to step 306, where the line usage rate measurement unit 64 measures the line usage rate of the first line for the transfer data for two colors.

  The line utilization rate measuring unit 64 measures the line utilization rate according to the following procedure. First, the data transfer period counter 66 of the line utilization rate measuring unit 64 sets the period from the start to the end of the operation of the main scanning counter 55 that operates for each line data (that is, the time required for counting the main scanning size) as the data transfer period. Measure as In step 306, a period required for transferring data for two colors is measured as a data transfer period.

  The line usage rate measuring unit 64 calculates the line usage rate by the following equation (4) based on the data transfer period measured by the data transfer period counter 66 and the lsync cycle acquired from the register control unit 54, and the line usage rate is calculated. Is output to the ASPM availability determination unit 62.

(In the above formula (4), (inter-drum pitch% lsync cycle) indicates a time corresponding to a remainder when the inter-drum pitch is divided by the lsync cycle.)

  In subsequent step 307, the ASPM availability determination unit 62 compares the line usage rate input from the line usage rate measurement unit 64 with the line usage rate threshold held in the line usage rate threshold setting unit 63. As a result, if it is determined that the line usage rate is smaller than the line usage rate threshold (step 307, Yes), the process proceeds to step 308. In Step 308, the ASPM availability determination unit 62 enables (ON) ASPM. Thereafter, the process waits for completion of the job being executed (No in Step 309), and when the activation flag is negated (Yes in Step 309), the process ends.

  On the other hand, if another channel is activated (step 310, Yes) while the job being executed is not completed (step 309, No), the process returns to step 302.

  On the other hand, if it is determined in step 307 that the line usage rate is not smaller than the line usage rate threshold (step 307, No), the completion of the job being executed is waited (step 311, No), and the activation flag is negated. Then (step 311; Yes), the process proceeds to step 312 to enable (ON) ASPM, and then the process ends.

  On the other hand, if another channel is activated (step 313, Yes) while the job being executed is not completed (step 311: No), the process returns to step 302.

  As described above, according to the present embodiment, there is no need to prepare software for each model or use case and perform ASPM ON / OFF control, and isochronous data transfer is performed by the internal mechanism of the PCIe device. Since ASPM is selectively controlled to be enabled only when the cost is not sacrificed, the power saving effect in the image processing apparatus is maximized.

  As described above, the present invention has been described with the embodiment. However, the present invention is not limited to the above-described embodiment, and as long as the operations and effects of the present invention are exhibited within the scope of embodiments that can be considered by those skilled in the art. It is included in the scope of the present invention.

10 ... IPU board 11,12,14,21 ... ASIC
13,22 ... CPU
DESCRIPTION OF SYMBOLS 15 ... Scanner 16 ... Plotter 20 ... CTL board 23 ... Memory 30 ... PCIe Root module 31 ... PCIE logic layer circuit 32 ... Config register control part 33 ... Data transfer control part 34 ... lsync signal generation part 35 ... Main scanning counter 36 ... Register Control unit 38 ... End Point module 40 ... ASPM control unit 42 ... ASPM availability determination unit 43 ... Line usage rate threshold setting unit 44 ... Line usage rate measurement unit 46 ... Data transfer period counter 50 ... PCIe Root module 51 ... PCIE logical layer Circuit 52 ... Config register control unit 53 ... Data transfer control unit 54 ... Register control unit 55 ... Main scan counter 56 ... Printer data transfer module 57 ... Arbiter 58 ... Memory controller 60 ... ASPM control unit 62 ... ASPM availability determination unit 63 ... Line usage rate threshold setting unit 64 ... Line usage rate measurement unit 66 ... Data Period counter feed

JP 2009-176294 A

Claims (10)

An image forming apparatus provided in an image processing unit with a plurality of devices connected by a serial bus,
The device is
A line usage rate measurement unit for measuring the line usage rate during data transfer;
A power management function availability determination unit that controls availability of a power management function related to power saving of the serial bus,
The power management function availability determination unit
Enabling the power management function only when the line utilization is less than a predetermined line utilization threshold,
Image forming apparatus.   The image forming apparatus according to claim 1, wherein the serial bus is PCI Express. The image forming apparatus according to claim 1, wherein the line utilization rate threshold is defined by the following formula (1).
(In the above formula (1), the transition preparation time indicates the time until the transition from the normal state to the power saving state is started, and the return time indicates the time until the transition from the power saving state to the normal state. .)   The image forming apparatus according to claim 3, wherein the value of the return time is a larger value of two return times specific to two connected devices. The image forming apparatus according to claim 1, wherein the line usage rate measurement unit measures a line usage rate of a first line based on the following formula (2).
An image forming apparatus provided in an image processing unit with a plurality of devices connected by a serial bus,
The device is
A line usage rate measurement unit for measuring the line usage rate during data transfer;
A power management function availability determination unit that controls availability of a power management function related to power saving of the serial bus,
The power management function availability determination unit
During the period in which the scanner data transfer and the printer data transfer are executed at the same time or the period in which only the full color printer data transfer is executed, the power management function is controlled to be disabled,
In the period in which only the scanner data transfer from the upstream device is executed, the power management function is controlled following the control content related to the power management function in the upstream device,
In a period in which only monochrome or two-color printer data transfer is executed, the power management function is controlled to be enabled only when the line usage rate is smaller than a predetermined line usage rate threshold.
Image forming apparatus.   The image forming apparatus according to claim 6, wherein the serial bus is PCI Express. The image forming apparatus according to claim 6, wherein the line utilization rate threshold is defined by the following formula (3).
(In the above formula (3), the transition preparation time indicates the time until the transition from the normal state to the power saving state is started, and the return time indicates the time until the transition from the power saving state to the normal state. , (Pitch between drums% lsync cycle) indicates the time corresponding to the remainder when the pitch between drums is divided by the lsync cycle.)   The image forming apparatus according to claim 8, wherein the value of the return time is a larger value of two return times specific to two connected devices. The image forming apparatus according to claim 6, wherein the line usage rate measurement unit measures the line usage rate of the first line based on the following formula (4).
(In the above formula (4), (inter-drum pitch% lsync cycle) indicates a time corresponding to a remainder when the inter-drum pitch is divided by the lsync cycle.)